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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html>
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<html xmlns="http://www.w3.org/1999/xhtml">
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  <body>
    <h1>Domain XML format</h1>

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    <ul id="toc"></ul>

    <p>
      This section describes the XML format used to represent domains, there are
      variations on the format based on the kind of domains run and the options
      used to launch them. For hypervisor specific details consult the
      <a href="drivers.html">driver docs</a>
    </p>


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    <h2><a id="elements">Element and attribute overview</a></h2>
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    <p>
      The root element required for all virtual machines is
      named <code>domain</code>. It has two attributes, the
      <code>type</code> specifies the hypervisor used for running
      the domain. The allowed values are driver specific, but
      include "xen", "kvm", "qemu", "lxc" and "kqemu". The
      second attribute is <code>id</code> which is a unique
      integer identifier for the running guest machine. Inactive
      machines have no id value.
    </p>


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    <h3><a id="elementsMetadata">General metadata</a></h3>
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<pre>
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&lt;domain type='kvm' id='1'&gt;
  &lt;name&gt;MyGuest&lt;/name&gt;
  &lt;uuid&gt;4dea22b3-1d52-d8f3-2516-782e98ab3fa0&lt;/uuid&gt;
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  &lt;genid&gt;43dc0cf8-809b-4adb-9bea-a9abb5f3d90e&lt;/genid&gt;
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  &lt;title&gt;A short description - title - of the domain&lt;/title&gt;
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  &lt;description&gt;Some human readable description&lt;/description&gt;
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  &lt;metadata&gt;
    &lt;app1:foo xmlns:app1="http://app1.org/app1/"&gt;..&lt;/app1:foo&gt;
    &lt;app2:bar xmlns:app2="http://app1.org/app2/"&gt;..&lt;/app2:bar&gt;
  &lt;/metadata&gt;
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  ...</pre>
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    <dl>
      <dt><code>name</code></dt>
      <dd>The content of the <code>name</code> element provides
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        a short name for the virtual machine. This name should
        consist only of alpha-numeric characters and is required
        to be unique within the scope of a single host. It is
        often used to form the filename for storing the persistent
        configuration file. <span class="since">Since 0.0.1</span></dd>
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      <dt><code>uuid</code></dt>
      <dd>The content of the <code>uuid</code> element provides
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        a globally unique identifier for the virtual machine.
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        The format must be RFC 4122 compliant,
        eg <code>3e3fce45-4f53-4fa7-bb32-11f34168b82b</code>.
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        If omitted when defining/creating a new machine, a random
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        UUID is generated. It is also possible to provide the UUID
        via a <a href="#elementsSysinfo"><code>sysinfo</code></a>
        specification. <span class="since">Since 0.0.1, sysinfo
        since 0.8.7</span></dd>
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      <dt><code>genid</code></dt>
      <dd><span class="since">Since 4.4.0</span>, the <code>genid</code>
        element can be used to add a Virtual Machine Generation ID which
        exposes a 128-bit, cryptographically random, integer value identifier,
        referred to as a Globally Unique Identifier (GUID) using the same
        format as the <code>uuid</code>. The value is used to help notify
        the guest operating system when the virtual machine is re-executing
        something that has already executed before, such as:

        <ul>
          <li>VM starts executing a snapshot</li>
          <li>VM is recovered from backup</li>
          <li>VM is failover in a disaster recovery environment</li>
          <li>VM is imported, copied, or cloned</li>
        </ul>

        The guest operating system notices the change and is then able to
        react as appropriate by marking its copies of distributed databases
        as dirty, re-initializing its random number generator, etc.

        <p>
        The libvirt XML parser will accept both a provided GUID value
        or just &lt;genid/&gt; in which case a GUID will be generated
        and saved in the XML. For the transitions such as above, libvirt
        will change the GUID before re-executing.</p></dd>

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      <dt><code>title</code></dt>
      <dd>The optional element <code>title</code> provides space for a
        short description of the domain. The title should not contain
        any newlines. <span class="since">Since 0.9.10</span>.</dd>

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      <dt><code>description</code></dt>
      <dd>The content of the <code>description</code> element provides a
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        human readable description of the virtual machine. This data is not
        used by libvirt in any way, it can contain any information the user
        wants. <span class="since">Since 0.7.2</span></dd>

      <dt><code>metadata</code></dt>
      <dd>The <code>metadata</code> node can be used by applications
        to store custom metadata in the form of XML
        nodes/trees. Applications must use custom namespaces on their
        XML nodes/trees, with only one top-level element per namespace
        (if the application needs structure, they should have
        sub-elements to their namespace
        element). <span class="since">Since 0.9.10</span></dd>
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   </dl>
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    <h3><a id="elementsOS">Operating system booting</a></h3>
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    <p>
      There are a number of different ways to boot virtual machines
      each with their own pros and cons.
    </p>

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    <h4><a id="elementsOSBIOS">BIOS bootloader</a></h4>
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    <p>
      Booting via the BIOS is available for hypervisors supporting
      full virtualization. In this case the BIOS has a boot order
      priority (floppy, harddisk, cdrom, network) determining where
      to obtain/find the boot image.
    </p>

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<pre>
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...
&lt;os&gt;
  &lt;type&gt;hvm&lt;/type&gt;
  &lt;loader readonly='yes' secure='no' type='rom'&gt;/usr/lib/xen/boot/hvmloader&lt;/loader&gt;
  &lt;nvram template='/usr/share/OVMF/OVMF_VARS.fd'&gt;/var/lib/libvirt/nvram/guest_VARS.fd&lt;/nvram&gt;
  &lt;boot dev='hd'/&gt;
  &lt;boot dev='cdrom'/&gt;
  &lt;bootmenu enable='yes' timeout='3000'/&gt;
  &lt;smbios mode='sysinfo'/&gt;
  &lt;bios useserial='yes' rebootTimeout='0'/&gt;
&lt;/os&gt;
...</pre>
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    <dl>
      <dt><code>type</code></dt>
      <dd>The content of the <code>type</code> element specifies the
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        type of operating system to be booted in the virtual machine.
        <code>hvm</code> indicates that the OS is one designed to run
        on bare metal, so requires full virtualization. <code>linux</code>
        (badly named!) refers to an OS that supports the Xen 3 hypervisor
        guest ABI. There are also two optional attributes, <code>arch</code>
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        specifying the CPU architecture to virtualization,
        and <code>machine</code> referring to the machine
        type. The <a href="formatcaps.html">Capabilities XML</a>
        provides details on allowed values for
        these. <span class="since">Since 0.0.1</span></dd>
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      <dt><code>loader</code></dt>
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      <dd>The optional <code>loader</code> tag refers to a firmware blob,
        which is specified by absolute path,
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        used to assist the domain creation process. It is used by Xen
        fully virtualized domains as well as setting the QEMU BIOS file
        path for QEMU/KVM domains. <span class="since">Xen since 0.1.0,
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        QEMU/KVM since 0.9.12</span> Then, <span class="since">since
        1.2.8</span> it's possible for the element to have two
        optional attributes: <code>readonly</code> (accepted values are
        <code>yes</code> and <code>no</code>) to reflect the fact that the
        image should be writable or read-only. The second attribute
        <code>type</code> accepts values <code>rom</code> and
        <code>pflash</code>. It tells the hypervisor where in the guest
        memory the file should be mapped.  For instance, if the loader
        path points to an UEFI image, <code>type</code> should be
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        <code>pflash</code>. Moreover, some firmwares may
        implement the Secure boot feature. Attribute
        <code>secure</code> can be used then to control it.
        <span class="since">Since 2.1.0</span></dd>
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      <dt><code>nvram</code></dt>
      <dd>Some UEFI firmwares may want to use a non-volatile memory to store
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        some variables. In the host, this is represented as a file and the
        absolute path to the file is stored in this element. Moreover, when the
        domain is started up libvirt copies so called master NVRAM store file
        defined in <code>qemu.conf</code>. If needed, the <code>template</code>
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        attribute can be used to per domain override map of master NVRAM stores
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        from the config file. Note, that for transient domains if the NVRAM file
        has been created by libvirt it is left behind and it is management
        application's responsibility to save and remove file (if needed to be
        persistent). <span class="since">Since 1.2.8</span></dd>
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      <dt><code>boot</code></dt>
      <dd>The <code>dev</code> attribute takes one of the values "fd", "hd",
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        "cdrom" or "network" and is used to specify the next boot device
        to consider. The <code>boot</code> element can be repeated multiple
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        times to setup a priority list of boot devices to try in turn.
        Multiple devices of the same type are sorted according to their
        targets while preserving the order of buses. After defining the
        domain, its XML configuration returned by libvirt (through
        virDomainGetXMLDesc) lists devices in the sorted order. Once sorted,
        the first device is marked as bootable. Thus, e.g., a domain
        configured to boot from "hd" with vdb, hda, vda, and hdc disks
        assigned to it will boot from vda (the sorted list is vda, vdb, hda,
        hdc). Similar domain with hdc, vda, vdb, and hda disks will boot from
        hda (sorted disks are: hda, hdc, vda, vdb). It can be tricky to
        configure in the desired way, which is why per-device boot elements
        (see <a href="#elementsDisks">disks</a>,
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        <a href="#elementsNICS">network interfaces</a>, and
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        <a href="#elementsHostDev">USB and PCI devices</a> sections below) were
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        introduced and they are the preferred way providing full control over
        booting order. The <code>boot</code> element and per-device boot
        elements are mutually exclusive. <span class="since">Since 0.1.3,
        per-device boot since 0.8.8</span>
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      </dd>
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      <dt><code>smbios</code></dt>
      <dd>How to populate SMBIOS information visible in the guest.
        The <code>mode</code> attribute must be specified, and is either
        "emulate" (let the hypervisor generate all values), "host" (copy
        all of Block 0 and Block 1, except for the UUID, from the host's
        SMBIOS values;
        the <a href="html/libvirt-libvirt-host.html#virConnectGetSysinfo">
        <code>virConnectGetSysinfo</code></a> call can be
        used to see what values are copied), or "sysinfo" (use the values in
        the <a href="#elementsSysinfo">sysinfo</a> element).  If not
        specified, the hypervisor default is used. <span class="since">
        Since 0.8.7</span>
      </dd>
  </dl>
      <p>Up till here the BIOS/UEFI configuration knobs are generic enough to
      be implemented by majority (if not all) firmwares out there. However,
      from now on not every single setting makes sense to all firmwares. For
      instance, <code>rebootTimeout</code> doesn't make sense for UEFI,
      <code>useserial</code> might not be usable with a BIOS firmware that
      doesn't produce any output onto serial line, etc. Moreover, firmwares
      don't usually export their capabilities for libvirt (or users) to check.
      And the set of their capabilities can change with every new release.
      Hence users are advised to try the settings they use before relying on
      them in production.</p>
  <dl>
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      <dt><code>bootmenu</code></dt>
      <dd> Whether or not to enable an interactive boot menu prompt on guest
      startup. The <code>enable</code> attribute can be either "yes" or "no".
      If not specified, the hypervisor default is used. <span class="since">
      Since 0.8.3</span>
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      Additional attribute <code>timeout</code> takes the number of milliseconds
      the boot menu should wait until it times out.  Allowed values are numbers
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      in range [0, 65535] inclusive and it is ignored unless <code>enable</code>
      is set to "yes". <span class="since">Since 1.2.8</span>
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      </dd>
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      <dt><code>bios</code></dt>
      <dd>This element has attribute <code>useserial</code> with possible
        values <code>yes</code> or <code>no</code>. It enables or disables
        Serial Graphics Adapter which allows users to see BIOS messages
        on a serial port. Therefore, one needs to have
        <a href="#elementCharSerial">serial port</a> defined.
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        <span class="since">Since 0.9.4</span>.
        <span class="since">Since 0.10.2 (QEMU only)</span> there is
        another attribute, <code>rebootTimeout</code> that controls
        whether and after how long the guest should start booting
        again in case the boot fails (according to BIOS). The value is
        in milliseconds with maximum of <code>65535</code> and special
        value <code>-1</code> disables the reboot.
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      </dd>
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    </dl>

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    <h4><a id="elementsOSBootloader">Host bootloader</a></h4>
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    <p>
      Hypervisors employing paravirtualization do not usually emulate
      a BIOS, and instead the host is responsible to kicking off the
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      operating system boot. This may use a pseudo-bootloader in the
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      host to provide an interface to choose a kernel for the guest.
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      An example is <code>pygrub</code> with Xen. The Bhyve hypervisor
      also uses a host bootloader, either <code>bhyveload</code> or
      <code>grub-bhyve</code>.
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    </p>

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<pre>
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...
&lt;bootloader&gt;/usr/bin/pygrub&lt;/bootloader&gt;
&lt;bootloader_args&gt;--append single&lt;/bootloader_args&gt;
...</pre>
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    <dl>
      <dt><code>bootloader</code></dt>
      <dd>The content of the <code>bootloader</code> element provides
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        a fully qualified path to the bootloader executable in the
        host OS. This bootloader will be run to choose which kernel
        to boot. The required output of the bootloader is dependent
        on the hypervisor in use. <span class="since">Since 0.1.0</span></dd>
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      <dt><code>bootloader_args</code></dt>
      <dd>The optional <code>bootloader_args</code> element allows
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        command line arguments to be passed to the bootloader.
        <span class="since">Since 0.2.3</span>
        </dd>
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    </dl>

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    <h4><a id="elementsOSKernel">Direct kernel boot</a></h4>
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    <p>
      When installing a new guest OS it is often useful to boot directly
      from a kernel and initrd stored in the host OS, allowing command
      line arguments to be passed directly to the installer. This capability
      is usually available for both para and full virtualized guests.
    </p>

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<pre>
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...
&lt;os&gt;
  &lt;type&gt;hvm&lt;/type&gt;
  &lt;loader&gt;/usr/lib/xen/boot/hvmloader&lt;/loader&gt;
  &lt;kernel&gt;/root/f8-i386-vmlinuz&lt;/kernel&gt;
  &lt;initrd&gt;/root/f8-i386-initrd&lt;/initrd&gt;
  &lt;cmdline&gt;console=ttyS0 ks=http://example.com/f8-i386/os/&lt;/cmdline&gt;
  &lt;dtb&gt;/root/ppc.dtb&lt;/dtb&gt;
  &lt;acpi&gt;
    &lt;table type='slic'&gt;/path/to/slic.dat&lt;/table&gt;
  &lt;/acpi&gt;
&lt;/os&gt;
...</pre>
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    <dl>
      <dt><code>type</code></dt>
      <dd>This element has the same semantics as described earlier in the
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        <a href="#elementsOSBIOS">BIOS boot section</a></dd>
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      <dt><code>loader</code></dt>
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      <dd>This element has the same semantics as described earlier in the
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        <a href="#elementsOSBIOS">BIOS boot section</a></dd>
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      <dt><code>kernel</code></dt>
      <dd>The contents of this element specify the fully-qualified path
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        to the kernel image in the host OS.</dd>
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      <dt><code>initrd</code></dt>
      <dd>The contents of this element specify the fully-qualified path
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        to the (optional) ramdisk image in the host OS.</dd>
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      <dt><code>cmdline</code></dt>
      <dd>The contents of this element specify arguments to be passed to
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        the kernel (or installer) at boot time. This is often used to
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        specify an alternate primary console (eg serial port), or the
        installation media source / kickstart file</dd>
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      <dt><code>dtb</code></dt>
      <dd>The contents of this element specify the fully-qualified path
        to the (optional) device tree binary (dtb) image in the host OS.
        <span class="since">Since 1.0.4</span></dd>
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      <dt><code>acpi</code></dt>
      <dd>The <code>table</code> element contains a fully-qualified path
        to the ACPI table. The <code>type</code> attribute contains the
        ACPI table type (currently only <code>slic</code> is supported)
        <span class="since">Since 1.3.5 (QEMU only)</span></dd>
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    </dl>

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    <h4><a id="elementsOSContainer">Container boot</a></h4>
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    <p>
      When booting a domain using container based virtualization, instead
      of a kernel / boot image, a path to the init binary is required, using
      the <code>init</code> element. By default this will be launched with
      no arguments. To specify the initial argv, use the <code>initarg</code>
      element, repeated as many time as is required. The <code>cmdline</code>
      element, if set will be used to provide an equivalent to <code>/proc/cmdline</code>
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      but will not affect init argv.
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    </p>
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    <p>
      To set environment variables, use the <code>initenv</code> element, one
      for each variable.
    </p>
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    <p>
      To set a custom work directory for the init, use the <code>initdir</code>
      element.
    </p>
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    <p>
      To run the init command as a given user or group, use the <code>inituser</code>
      or <code>initgroup</code> elements respectively. Both elements can be provided
      either a user (resp. group) id or a name. Prefixing the user or group id with
      a <code>+</code> will force it to be considered like a numeric value. Without
      this, it will be first tried as a user or group name.
    </p>
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    <pre>
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&lt;os&gt;
  &lt;type arch='x86_64'&gt;exe&lt;/type&gt;
  &lt;init&gt;/bin/systemd&lt;/init&gt;
  &lt;initarg&gt;--unit&lt;/initarg&gt;
  &lt;initarg&gt;emergency.service&lt;/initarg&gt;
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  &lt;initenv name='MYENV'&gt;some value&lt;/initenv&gt;
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  &lt;initdir&gt;/my/custom/cwd&lt;/initdir&gt;
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  &lt;inituser&gt;tester&lt;/inituser&gt;
  &lt;initgroup&gt;1000&lt;/initgroup&gt;
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&lt;/os&gt;
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    </pre>


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    <p>
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      If you want to enable user namespace, set the <code>idmap</code> element.
      The <code>uid</code> and <code>gid</code> elements have three attributes:
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    </p>

    <dl>
      <dt><code>start</code></dt>
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      <dd>First user ID in container. It must be '0'.</dd>
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      <dt><code>target</code></dt>
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      <dd>The first user ID in container will be mapped to this target user
          ID in host.</dd>
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      <dt><code>count</code></dt>
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      <dd>How many users in container are allowed to map to host's user.</dd>
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    </dl>

    <pre>
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&lt;idmap&gt;
  &lt;uid start='0' target='1000' count='10'/&gt;
  &lt;gid start='0' target='1000' count='10'/&gt;
&lt;/idmap&gt;
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    </pre>


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    <h3><a id="elementsSysinfo">SMBIOS System Information</a></h3>
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    <p>
      Some hypervisors allow control over what system information is
      presented to the guest (for example, SMBIOS fields can be
      populated by a hypervisor and inspected via
      the <code>dmidecode</code> command in the guest).  The
      optional <code>sysinfo</code> element covers all such categories
      of information. <span class="since">Since 0.8.7</span>
    </p>

<pre>
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...
&lt;os&gt;
  &lt;smbios mode='sysinfo'/&gt;
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  ...
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&lt;/os&gt;
&lt;sysinfo type='smbios'&gt;
  &lt;bios&gt;
    &lt;entry name='vendor'&gt;LENOVO&lt;/entry&gt;
  &lt;/bios&gt;
  &lt;system&gt;
    &lt;entry name='manufacturer'&gt;Fedora&lt;/entry&gt;
    &lt;entry name='product'&gt;Virt-Manager&lt;/entry&gt;
    &lt;entry name='version'&gt;0.9.4&lt;/entry&gt;
  &lt;/system&gt;
  &lt;baseBoard&gt;
    &lt;entry name='manufacturer'&gt;LENOVO&lt;/entry&gt;
    &lt;entry name='product'&gt;20BE0061MC&lt;/entry&gt;
    &lt;entry name='version'&gt;0B98401 Pro&lt;/entry&gt;
    &lt;entry name='serial'&gt;W1KS427111E&lt;/entry&gt;
  &lt;/baseBoard&gt;
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  &lt;chassis&gt;
    &lt;entry name='manufacturer'&gt;Dell Inc.&lt;/entry&gt;
    &lt;entry name='version'&gt;2.12&lt;/entry&gt;
    &lt;entry name='serial'&gt;65X0XF2&lt;/entry&gt;
    &lt;entry name='asset'&gt;40000101&lt;/entry&gt;
    &lt;entry name='sku'&gt;Type3Sku1&lt;/entry&gt;
  &lt;/chassis&gt;
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  &lt;oemStrings&gt;
    &lt;entry&gt;myappname:some arbitrary data&lt;/entry&gt;
    &lt;entry&gt;otherappname:more arbitrary data&lt;/entry&gt;
  &lt;/oemStrings&gt;
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&lt;/sysinfo&gt;
...</pre>
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    <p>
      The <code>sysinfo</code> element has a mandatory
      attribute <code>type</code> that determine the layout of
      sub-elements, with supported values of:
    </p>

    <dl>
      <dt><code>smbios</code></dt>
      <dd>Sub-elements call out specific SMBIOS values, which will
      affect the guest if used in conjunction with
      the <code>smbios</code> sub-element of
      the <a href="#elementsOS"><code>os</code></a> element.  Each
      sub-element of <code>sysinfo</code> names a SMBIOS block, and
      within those elements can be a list of <code>entry</code>
      elements that describe a field within the block.  The following
      blocks and entries are recognized:
        <dl>
          <dt><code>bios</code></dt>
          <dd>
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            This is block 0 of SMBIOS, with entry names drawn from:
            <dl>
               <dt><code>vendor</code></dt>
               <dd>BIOS Vendor's Name</dd>
               <dt><code>version</code></dt>
               <dd>BIOS Version</dd>
               <dt><code>date</code></dt>
               <dd>BIOS release date. If supplied, is in either mm/dd/yy or
                   mm/dd/yyyy format. If the year portion of the string is
                   two digits, the year is assumed to be 19yy.</dd>
               <dt><code>release</code></dt>
               <dd>System BIOS Major and Minor release number values
                   concatenated together as one string separated by
                   a period, for example, 10.22.</dd>
           </dl>
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          </dd>
          <dt><code>system</code></dt>
          <dd>
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            This is block 1 of SMBIOS, with entry names drawn from:
            <dl>
                <dt><code>manufacturer</code></dt>
                <dd>Manufacturer of BIOS</dd>
                <dt><code>product</code></dt>
                <dd>Product Name</dd>
                <dt><code>version</code></dt>
                <dd>Version of the product</dd>
                <dt><code>serial</code></dt>
                <dd>Serial number</dd>
                <dt><code>uuid</code></dt>
                <dd>Universal Unique ID number. If this entry is provided
                alongside a top-level
                <a href="#elementsMetadata"><code>uuid</code></a> element,
                then the two values must match.</dd>
                <dt><code>sku</code></dt>
                <dd>SKU number to identify a particular configuration.</dd>
                <dt><code>family</code></dt>
                <dd>Identify the family a particular computer belongs to.</dd>
            </dl>
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          </dd>
          <dt><code>baseBoard</code></dt>
          <dd>
            This is block 2 of SMBIOS. This element can be repeated multiple
            times to describe all the base boards; however, not all
            hypervisors necessarily support the repetition. The element can
            have the following children:
            <dl>
                <dt><code>manufacturer</code></dt>
                <dd>Manufacturer of BIOS</dd>
                <dt><code>product</code></dt>
                <dd>Product Name</dd>
                <dt><code>version</code></dt>
                <dd>Version of the product</dd>
                <dt><code>serial</code></dt>
                <dd>Serial number</dd>
                <dt><code>asset</code></dt>
                <dd>Asset tag</dd>
                <dt><code>location</code></dt>
                <dd>Location in chassis</dd>
            </dl>
            NB: Incorrectly supplied entries for the
            <code>bios</code>, <code>system</code> or <code>baseBoard</code>
            blocks will be ignored without error.  Other than <code>uuid</code>
            validation and <code>date</code> format checking, all values are
            passed as strings to the hypervisor driver.
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          </dd>
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          <dt><code>chassis</code></dt>
          <dd>
            <span class="since">Since 4.1.0,</span> this is block 3 of
            SMBIOS, with entry names drawn from:
            <dl>
                <dt><code>manufacturer</code></dt>
                <dd>Manufacturer of Chassis</dd>
                <dt><code>version</code></dt>
                <dd>Version of the Chassis</dd>
                <dt><code>serial</code></dt>
                <dd>Serial number</dd>
                <dt><code>asset</code></dt>
                <dd>Asset tag</dd>
                <dt><code>sku</code></dt>
                <dd>SKU number</dd>
            </dl>
          </dd>
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          <dt><code>oemStrings</code></dt>
          <dd>
            This is block 11 of SMBIOS. This element should appear once and
            can have multiple <code>entry</code> child elements, each providing
            arbitrary string data. There are no restrictions on what data can
            be provided in the entries, however, if the data is intended to be
            consumed by an application in the guest, it is recommended to use
            the application name as a prefix in the string. (<span class="since">Since 4.1.0</span>)
          </dd>
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        </dl>
      </dd>
    </dl>

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    <h3><a id="elementsCPUAllocation">CPU Allocation</a></h3>
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<pre>
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&lt;domain&gt;
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  ...
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  &lt;vcpu placement='static' cpuset="1-4,^3,6" current="1"&gt;2&lt;/vcpu&gt;
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  &lt;vcpus&gt;
    &lt;vcpu id='0' enabled='yes' hotpluggable='no' order='1'/&gt;
    &lt;vcpu id='1' enabled='no' hotpluggable='yes'/&gt;
  &lt;/vcpus&gt;
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  ...
&lt;/domain&gt;
</pre>
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    <dl>
      <dt><code>vcpu</code></dt>
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      <dd>The content of this element defines the maximum number of virtual
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        CPUs allocated for the guest OS, which must be between 1 and
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        the maximum supported by the hypervisor.
        <dl>
         <dt><code>cpuset</code></dt>
         <dd>
           The optional attribute <code>cpuset</code> is a comma-separated
           list of physical CPU numbers that domain process and virtual CPUs
           can be pinned to by default. (NB: The pinning policy of domain
           process and virtual CPUs can be specified separately by
           <code>cputune</code>. If the attribute <code>emulatorpin</code>
           of <code>cputune</code> is specified, the <code>cpuset</code>
           specified by <code>vcpu</code> here will be ignored. Similarly,
           for virtual CPUs which have the <code>vcpupin</code> specified,
           the <code>cpuset</code> specified by <code>cpuset</code> here
           will be ignored. For virtual CPUs which don't have
           <code>vcpupin</code> specified, each will be pinned to the physical
           CPUs specified by <code>cpuset</code> here).
           Each element in that list is either a single CPU number,
           a range of CPU numbers, or a caret followed by a CPU number to
           be excluded from a previous range.
           <span class="since">Since 0.4.4</span>
         </dd>
         <dt><code>current</code></dt>
         <dd>
           The optional attribute <code>current</code> can
           be used to specify whether fewer than the maximum number of
           virtual CPUs should be enabled.
           <span class="since">Since 0.8.5</span>
         </dd>
         <dt><code>placement</code></dt>
         <dd>
           The optional attribute <code>placement</code> can be used to
           indicate the CPU placement mode for domain process. The value can
           be either "static" or "auto", but defaults to <code>placement</code>
           of <code>numatune</code> or "static" if <code>cpuset</code> is
           specified. Using "auto" indicates the domain process will be pinned
           to the advisory nodeset from querying numad and the value of
           attribute <code>cpuset</code> will be ignored if it's specified.
           If both <code>cpuset</code> and <code>placement</code> are not
           specified or if <code>placement</code> is "static", but no
           <code>cpuset</code> is specified, the domain process will be
           pinned to all the available physical CPUs.
           <span class="since">Since 0.9.11 (QEMU and KVM only)</span>
         </dd>
        </dl>
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      </dd>
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      <dt><code>vcpus</code></dt>
      <dd>
        The vcpus element allows to control state of individual vcpus.

        The <code>id</code> attribute specifies the vCPU id as used by libvirt
        in other places such as vcpu pinning, scheduler information and NUMA
        assignment. Note that the vcpu ID as seen in the guest may differ from
        libvirt ID in certain cases. Valid IDs are from 0 to the maximum vcpu
        count as set by the <code>vcpu</code> element minus 1.

        The <code>enabled</code> attribute allows to control the state of the
        vcpu. Valid values are <code>yes</code> and <code>no</code>.

        <code>hotpluggable</code> controls whether given vcpu can be hotplugged
        and hotunplugged in cases when the cpu is enabled at boot. Note that
        all disabled vcpus must be hotpluggable. Valid values are
        <code>yes</code> and <code>no</code>.

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        <code>order</code> allows to specify the order to add the online vcpus.
        For hypervisors/platforms that require to insert multiple vcpus at once
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        the order may be duplicated across all vcpus that need to be
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        enabled at once. Specifying order is not necessary, vcpus are then
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        added in an arbitrary order. If order info is used, it must be used for
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        all online vcpus. Hypervisors may clear or update ordering information
        during certain operations to assure valid configuration.
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        Note that hypervisors may create hotpluggable vcpus differently from
        boot vcpus thus special initialization may be necessary.

        Hypervisors may require that vcpus enabled on boot which are not
        hotpluggable are clustered at the beginning starting with ID 0. It may
        be also required that vcpu 0 is always present and non-hotpluggable.

        Note that providing state for individual cpus may be necessary to enable
        support of addressable vCPU hotplug and this feature may not be
        supported by all hypervisors.
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        For QEMU the following conditions are required. Vcpu 0 needs to be
        enabled and non-hotpluggable. On PPC64 along with it vcpus that are in
        the same core need to be enabled as well. All non-hotpluggable cpus
        present at boot need to be grouped after vcpu 0.
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        <span class="since">Since 2.2.0 (QEMU only)</span>
      </dd>
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    </dl>

677
    <h3><a id="elementsIOThreadsAllocation">IOThreads Allocation</a></h3>
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      <p>
        IOThreads are dedicated event loop threads for supported disk
        devices to perform block I/O requests in order to improve
        scalability especially on an SMP host/guest with many LUNs.
        <span class="since">Since 1.2.8 (QEMU only)</span>
      </p>

<pre>
&lt;domain&gt;
  ...
  &lt;iothreads&gt;4&lt;/iothreads&gt;
  ...
&lt;/domain&gt;
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</pre>
<pre>
&lt;domain&gt;
  ...
  &lt;iothreadids&gt;
    &lt;iothread id="2"/&gt;
    &lt;iothread id="4"/&gt;
    &lt;iothread id="6"/&gt;
    &lt;iothread id="8"/&gt;
  &lt;/iothreadids&gt;
  ...
&lt;/domain&gt;
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</pre>

    <dl>
      <dt><code>iothreads</code></dt>
      <dd>
        The content of this optional element defines the number
        of IOThreads to be assigned to the domain for use by
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        supported target storage devices. There
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        should be only 1 or 2 IOThreads per host CPU. There may be more
        than one supported device assigned to each IOThread.
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        <span class="since">Since 1.2.8</span>
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      </dd>
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      <dt><code>iothreadids</code></dt>
      <dd>
        The optional <code>iothreadids</code> element provides the capability
        to specifically define the IOThread ID's for the domain.  By default,
        IOThread ID's are sequentially numbered starting from 1 through the
        number of <code>iothreads</code> defined for the domain. The
        <code>id</code> attribute is used to define the IOThread ID. The
        <code>id</code> attribute must be a positive integer greater than 0.
        If there are less <code>iothreadids</code> defined than
        <code>iothreads</code> defined for the domain, then libvirt will
        sequentially fill <code>iothreadids</code> starting at 1 avoiding
        any predefined <code>id</code>. If there are more
        <code>iothreadids</code> defined than <code>iothreads</code>
        defined for the domain, then the <code>iothreads</code> value
        will be adjusted accordingly.
        <span class="since">Since 1.2.15</span>
       </dd>
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    </dl>
733

734
    <h3><a id="elementsCPUTuning">CPU Tuning</a></h3>
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<pre>
&lt;domain&gt;
  ...
  &lt;cputune&gt;
    &lt;vcpupin vcpu="0" cpuset="1-4,^2"/&gt;
    &lt;vcpupin vcpu="1" cpuset="0,1"/&gt;
    &lt;vcpupin vcpu="2" cpuset="2,3"/&gt;
    &lt;vcpupin vcpu="3" cpuset="0,4"/&gt;
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    &lt;emulatorpin cpuset="1-3"/&gt;
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    &lt;iothreadpin iothread="1" cpuset="5,6"/&gt;
    &lt;iothreadpin iothread="2" cpuset="7,8"/&gt;
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    &lt;shares&gt;2048&lt;/shares&gt;
    &lt;period&gt;1000000&lt;/period&gt;
    &lt;quota&gt;-1&lt;/quota&gt;
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    &lt;emulator_period&gt;1000000&lt;/emulator_period&gt;
    &lt;emulator_quota&gt;-1&lt;/emulator_quota&gt;
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    &lt;iothread_period&gt;1000000&lt;/iothread_period&gt;
    &lt;iothread_quota&gt;-1&lt;/iothread_quota&gt;
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    &lt;vcpusched vcpus='0-4,^3' scheduler='fifo' priority='1'/&gt;
    &lt;iothreadsched iothreads='2' scheduler='batch'/&gt;
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    &lt;cachetune vcpus='0-3'&gt;
      &lt;cache id='0' level='3' type='both' size='3' unit='MiB'/&gt;
      &lt;cache id='1' level='3' type='both' size='3' unit='MiB'/&gt;
    &lt;/cachetune&gt;
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  &lt;/cputune&gt;
  ...
&lt;/domain&gt;
</pre>

    <dl>
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      <dt><code>cputune</code></dt>
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      <dd>
         The optional <code>cputune</code> element provides details
         regarding the cpu tunable parameters for the domain.
         <span class="since">Since 0.9.0</span>
      </dd>
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      <dt><code>vcpupin</code></dt>
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      <dd>
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        The optional <code>vcpupin</code> element specifies which of host's
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        physical CPUs the domain VCPU will be pinned to. If this is omitted,
        and attribute <code>cpuset</code> of element <code>vcpu</code> is
        not specified, the vCPU is pinned to all the physical CPUs by default.
        It contains two required attributes, the attribute <code>vcpu</code>
        specifies vcpu id, and the attribute <code>cpuset</code> is same as
        attribute <code>cpuset</code> of element <code>vcpu</code>.
        (NB: Only qemu driver support)
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        <span class="since">Since 0.9.0</span>
       </dd>
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       <dt><code>emulatorpin</code></dt>
       <dd>
         The optional <code>emulatorpin</code> element specifies which of host
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         physical CPUs the "emulator", a subset of a domain not including vcpu
         or iothreads will be pinned to. If this is omitted, and attribute
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         <code>cpuset</code> of element <code>vcpu</code> is not specified,
         "emulator" is pinned to all the physical CPUs by default. It contains
         one required attribute <code>cpuset</code> specifying which physical
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         CPUs to pin to.
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       </dd>
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       <dt><code>iothreadpin</code></dt>
       <dd>
         The optional <code>iothreadpin</code> element specifies which of host
         physical CPUs the IOThreads will be pinned to. If this is omitted
         and attribute <code>cpuset</code> of element <code>vcpu</code> is
         not specified, the IOThreads are pinned to all the physical CPUs
         by default. There are two required attributes, the attribute
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         <code>iothread</code> specifies the IOThread ID and the attribute
         <code>cpuset</code> specifying which physical CPUs to pin to. See
         the <code>iothreadids</code>
         <a href="#elementsIOThreadsAllocation"><code>description</code></a>
         for valid <code>iothread</code> values.
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        <span class="since">Since 1.2.9</span>
       </dd>
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      <dt><code>shares</code></dt>
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      <dd>
        The optional <code>shares</code> element specifies the proportional
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        weighted share for the domain. If this is omitted, it defaults to
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        the OS provided defaults. NB, There is no unit for the value,
        it's a relative measure based on the setting of other VM,
        e.g. A VM configured with value
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        2048 will get twice as much CPU time as a VM configured with value 1024.
        <span class="since">Since 0.9.0</span>
      </dd>
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      <dt><code>period</code></dt>
      <dd>
        The optional <code>period</code> element specifies the enforcement
        interval(unit: microseconds). Within <code>period</code>, each vcpu of
        the domain will not be allowed to consume more than <code>quota</code>
        worth of runtime. The value should be in range [1000, 1000000]. A period
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        with value 0 means no value.
        <span class="since">Only QEMU driver support since 0.9.4, LXC since
        0.9.10</span>
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      </dd>
      <dt><code>quota</code></dt>
      <dd>
        The optional <code>quota</code> element specifies the maximum allowed
        bandwidth(unit: microseconds). A domain with <code>quota</code> as any
        negative value indicates that the domain has infinite bandwidth, which
        means that it is not bandwidth controlled. The value should be in range
        [1000, 18446744073709551] or less than 0. A quota with value 0 means no
        value. You can use this feature to ensure that all vcpus run at the same
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        speed.
        <span class="since">Only QEMU driver support since 0.9.4, LXC since
        0.9.10</span>
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      </dd>
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      <dt><code>emulator_period</code></dt>
      <dd>
        The optional <code>emulator_period</code> element specifies the enforcement
        interval(unit: microseconds). Within <code>emulator_period</code>, emulator
        threads(those excluding vcpus) of the domain will not be allowed to consume
        more than <code>emulator_quota</code> worth of runtime. The value should be
        in range [1000, 1000000]. A period with value 0 means no value.
        <span class="since">Only QEMU driver support since 0.10.0</span>
      </dd>
      <dt><code>emulator_quota</code></dt>
      <dd>
        The optional <code>emulator_quota</code> element specifies the maximum
        allowed bandwidth(unit: microseconds) for domain's emulator threads(those
        excluding vcpus). A domain with <code>emulator_quota</code> as any negative
        value indicates that the domain has infinite bandwidth for emulator threads
        (those excluding vcpus), which means that it is not bandwidth controlled.
        The value should be in range [1000, 18446744073709551] or less than 0. A
        quota with value 0 means no value.
        <span class="since">Only QEMU driver support since 0.10.0</span>
      </dd>

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      <dt><code>iothread_period</code></dt>
      <dd>
        The optional <code>iothread_period</code> element specifies the
        enforcement interval(unit: microseconds) for IOThreads. Within
        <code>iothread_period</code>, each IOThread of the domain will
        not be allowed to consume more than <code>iothread_quota</code>
        worth of runtime. The value should be in range [1000, 1000000].
        An iothread_period with value 0 means no value.
        <span class="since">Only QEMU driver support since 2.1.0</span>
      </dd>
      <dt><code>iothread_quota</code></dt>
      <dd>
        The optional <code>iothread_quota</code> element specifies the maximum
        allowed bandwidth(unit: microseconds) for IOThreads. A domain with
        <code>iothread_quota</code> as any negative value indicates that the
        domain IOThreads have infinite bandwidth, which means that it is
        not bandwidth controlled. The value should be in range
        [1000, 18446744073709551] or less than 0. An <code>iothread_quota</code>
        with value 0 means no value. You can use this feature to ensure that
        all IOThreads run at the same speed.
        <span class="since">Only QEMU driver support since 2.1.0</span>
      </dd>

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      <dt><code>vcpusched</code> and <code>iothreadsched</code></dt>
      <dd>
        The optional <code>vcpusched</code> elements specifies the scheduler
        type (values <code>batch</code>, <code>idle</code>, <code>fifo</code>,
        <code>rr</code>) for particular vCPU/IOThread threads (based on
        <code>vcpus</code> and <code>iothreads</code>, leaving out
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        <code>vcpus</code>/<code>iothreads</code> sets the default). Valid
        <code>vcpus</code> values start at 0 through one less than the
        number of vCPU's defined for the domain. Valid <code>iothreads</code>
        values are described in the <code>iothreadids</code>
        <a href="#elementsIOThreadsAllocation"><code>description</code></a>.
        If no <code>iothreadids</code> are defined, then libvirt numbers
        IOThreads from 1 to the number of <code>iothreads</code> available
        for the domain. For real-time schedulers (<code>fifo</code>,
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        <code>rr</code>), priority must be specified as
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        well (and is ignored for non-real-time ones). The value range
        for the priority depends on the host kernel (usually 1-99).
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        <span class="since">Since 1.2.13</span>
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      </dd>

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      <dt><code>cachetune</code><span class="since">Since 4.1.0</span></dt>
      <dd>
        Optional <code>cachetune</code> element can control allocations for CPU
        caches using the resctrl on the host. Whether or not is this supported
        can be gathered from capabilities where some limitations like minimum
        size and required granularity are reported as well. The required
        attribute <code>vcpus</code> specifies to which vCPUs this allocation
        applies. A vCPU can only be member of one <code>cachetune</code> element
        allocations. Supported subelements are:
        <dl>
          <dt><code>cache</code></dt>
          <dd>
            This element controls the allocation of CPU cache and has the
            following attributes:
            <dl>
              <dt><code>level</code></dt>
              <dd>
                Host cache level from which to allocate.
              </dd>
              <dt><code>id</code></dt>
              <dd>
                Host cache id from which to allocate.
              </dd>
              <dt><code>type</code></dt>
              <dd>
                Type of allocation. Can be <code>code</code> for code
                (instructions), <code>data</code> for data or <code>both</code>
                for both code and data (unified). Currently the allocation can
                be done only with the same type as the host supports, meaning
                you cannot request <code>both</code> for host with CDP
                (code/data prioritization) enabled.
              </dd>
              <dt><code>size</code></dt>
              <dd>
                The size of the region to allocate. The value by default is in
                bytes, but the <code>unit</code> attribute can be used to scale
                the value.
              </dd>
              <dt><code>unit</code> (optional)</dt>
              <dd>
                If specified it is the unit such as KiB, MiB, GiB, or TiB
                (described in the <code>memory</code> element
                for <a href="#elementsMemoryAllocation">Memory Allocation</a>)
                in which <code>size</code> is specified, defaults to bytes.
              </dd>
            </dl>
          </dd>
        </dl>

      </dd>
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    </dl>


958
    <h3><a id="elementsMemoryAllocation">Memory Allocation</a></h3>
959 960 961 962

<pre>
&lt;domain&gt;
  ...
963
  &lt;maxMemory slots='16' unit='KiB'&gt;1524288&lt;/maxMemory&gt;
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  &lt;memory unit='KiB'&gt;524288&lt;/memory&gt;
  &lt;currentMemory unit='KiB'&gt;524288&lt;/currentMemory&gt;
966 967 968 969 970 971
  ...
&lt;/domain&gt;
</pre>

    <dl>
      <dt><code>memory</code></dt>
972 973 974
      <dd>The maximum allocation of memory for the guest at boot time. The
        memory allocation includes possible additional memory devices specified
        at start or hotplugged later.
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        The units for this value are determined by the optional
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        attribute <code>unit</code>, which defaults to "KiB"
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        (kibibytes, 2<sup>10</sup> or blocks of 1024 bytes).  Valid
        units are "b" or "bytes" for bytes, "KB" for kilobytes
        (10<sup>3</sup> or 1,000 bytes), "k" or "KiB" for kibibytes
        (1024 bytes), "MB" for megabytes (10<sup>6</sup> or 1,000,000
        bytes), "M" or "MiB" for mebibytes (2<sup>20</sup> or
        1,048,576 bytes), "GB" for gigabytes (10<sup>9</sup> or
        1,000,000,000 bytes), "G" or "GiB" for gibibytes
        (2<sup>30</sup> or 1,073,741,824 bytes), "TB" for terabytes
        (10<sup>12</sup> or 1,000,000,000,000 bytes), or "T" or "TiB"
        for tebibytes (2<sup>40</sup> or 1,099,511,627,776 bytes).
        However, the value will be rounded up to the nearest kibibyte
        by libvirt, and may be further rounded to the granularity
        supported by the hypervisor.  Some hypervisors also enforce a
990 991
        minimum, such as 4000KiB.

992 993 994
        In case <a href="#elementsCPU">NUMA</a> is configured for the guest the
        <code>memory</code> element can be omitted.

995 996 997 998 999 1000 1001
        In the case of crash, optional attribute <code>dumpCore</code>
        can be used to control whether the guest memory should be
        included in the generated coredump or not (values "on", "off").

        <span class='since'><code>unit</code> since 0.9.11</span>,
        <span class='since'><code>dumpCore</code> since 0.10.2
        (QEMU only)</span></dd>
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      <dt><code>maxMemory</code></dt>
      <dd>The run time maximum memory allocation of the guest. The initial
        memory specified by either the <code>&lt;memory&gt;</code> element or
        the NUMA cell size configuration can be increased by hot-plugging of
        memory to the limit specified by this element.

        The <code>unit</code> attribute behaves the same as for
        <code>&lt;memory&gt;</code>.

        The <code>slots</code> attribute specifies the number of slots
        available for adding memory to the guest. The bounds are hypervisor
        specific.

        Note that due to alignment of the memory chunks added via memory
        hotplug the full size allocation specified by this element may be
        impossible to achieve.
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        <span class='since'>Since 1.2.14 supported by the QEMU driver.</span>
1019 1020
      </dd>

1021 1022 1023 1024
      <dt><code>currentMemory</code></dt>
      <dd>The actual allocation of memory for the guest. This value can
        be less than the maximum allocation, to allow for ballooning
        up the guests memory on the fly. If this is omitted, it defaults
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        to the same value as the <code>memory</code> element.
        The <code>unit</code> attribute behaves the same as
        for <code>memory</code>.</dd>
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    </dl>


1031
    <h3><a id="elementsMemoryBacking">Memory Backing</a></h3>
1032 1033 1034 1035 1036

<pre>
&lt;domain&gt;
  ...
  &lt;memoryBacking&gt;
1037 1038 1039
    &lt;hugepages&gt;
      &lt;page size="1" unit="G" nodeset="0-3,5"/&gt;
      &lt;page size="2" unit="M" nodeset="4"/&gt;
1040
    &lt;/hugepages&gt;
1041
    &lt;nosharepages/&gt;
1042
    &lt;locked/&gt;
1043 1044 1045
    &lt;source type="file|anonymous"/&gt;
    &lt;access mode="shared|private"/&gt;
    &lt;allocation mode="immediate|ondemand"/&gt;
1046
    &lt;discard/&gt;
1047 1048 1049 1050 1051
  &lt;/memoryBacking&gt;
  ...
&lt;/domain&gt;
</pre>

1052 1053 1054 1055
    <p>The optional <code>memoryBacking</code> element may contain several
      elements that influence how virtual memory pages are backed by host
      pages.</p>

1056
    <dl>
1057 1058
      <dt><code>hugepages</code></dt>
      <dd>This tells the hypervisor that the guest should have its memory
1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071
      allocated using hugepages instead of the normal native page size.
      <span class='since'>Since 1.2.5</span> it's possible to set hugepages
      more specifically per numa node. The <code>page</code> element is
      introduced. It has one compulsory attribute <code>size</code> which
      specifies which hugepages should be used (especially useful on systems
      supporting hugepages of different sizes). The default unit for the
      <code>size</code> attribute is kilobytes (multiplier of 1024). If you
      want to use different unit, use optional <code>unit</code> attribute.
      For systems with NUMA, the optional <code>nodeset</code> attribute may
      come handy as it ties given guest's NUMA nodes to certain hugepage
      sizes. From the example snippet, one gigabyte hugepages are used for
      every NUMA node except node number four. For the correct syntax see
      <a href="#elementsNUMATuning">this</a>.</dd>
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      <dt><code>nosharepages</code></dt>
      <dd>Instructs hypervisor to disable shared pages (memory merge, KSM) for
        this domain. <span class="since">Since 1.0.6</span></dd>
      <dt><code>locked</code></dt>
      <dd>When set and supported by the hypervisor, memory pages belonging
        to the domain will be locked in host's memory and the host will not
1078 1079 1080 1081 1082 1083 1084 1085
        be allowed to swap them out, which might be required for some
        workloads such as real-time. For QEMU/KVM guests, the memory used by
        the QEMU process itself will be locked too: unlike guest memory, this
        is an amount libvirt has no way of figuring out in advance, so it has
        to remove the limit on locked memory altogether. Thus, enabling this
        option opens up to a potential security risk: the host will be unable
        to reclaim the locked memory back from the guest when it's running out
        of memory, which means a malicious guest allocating large amounts of
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        locked memory could cause a denial-of-service attack on the host.
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        Because of this, using this option is discouraged unless your workload
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        demands it; even then, it's highly recommended to set a
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        <code>hard_limit</code> (see
        <a href="#elementsMemoryTuning">memory tuning</a>) on memory allocation
        suitable for the specific environment at the same time to mitigate
        the risks described above. <span class="since">Since 1.0.6</span></dd>
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       <dt><code>source</code></dt>
1094 1095
       <dd>In this attribute you can switch to file memorybacking or keep
         default anonymous.</dd>
1096
       <dt><code>access</code></dt>
1097 1098
       <dd>Specify if memory is shared or private. This can be overridden per
         numa node by <code>memAccess</code></dd>
1099 1100
       <dt><code>allocation</code></dt>
       <dd>Specify when allocate the memory</dd>
1101 1102 1103 1104 1105 1106 1107 1108
       <dt><code>discard</code></dt>
       <dd>When set and supported by hypervisor the memory
         content is discarded just before guest shuts down (or
         when DIMM module is unplugged). Please note that this is
         just an optimization and is not guaranteed to work in
         all cases (e.g. when hypervisor crashes).
         <span class="since">Since 4.4.0</span> (QEMU/KVM only)
       </dd>
1109 1110 1111
    </dl>


1112
    <h3><a id="elementsMemoryTuning">Memory Tuning</a></h3>
1113 1114 1115 1116 1117

<pre>
&lt;domain&gt;
  ...
  &lt;memtune&gt;
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    &lt;hard_limit unit='G'&gt;1&lt;/hard_limit&gt;
    &lt;soft_limit unit='M'&gt;128&lt;/soft_limit&gt;
    &lt;swap_hard_limit unit='G'&gt;2&lt;/swap_hard_limit&gt;
    &lt;min_guarantee unit='bytes'&gt;67108864&lt;/min_guarantee&gt;
1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134
  &lt;/memtune&gt;
  ...
&lt;/domain&gt;
</pre>

    <dl>
      <dt><code>memtune</code></dt>
      <dd> The optional <code>memtune</code> element provides details
        regarding the memory tunable parameters for the domain. If this is
        omitted, it defaults to the OS provided defaults. For QEMU/KVM, the
        parameters are applied to the QEMU process as a whole. Thus, when
        counting them, one needs to add up guest RAM, guest video RAM, and
        some memory overhead of QEMU itself. The last piece is hard to
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        determine so one needs guess and try.  For each tunable, it
        is possible to designate which unit the number is in on
        input, using the same values as
        for <code>&lt;memory&gt;</code>.  For backwards
        compatibility, output is always in
        KiB.  <span class='since'><code>unit</code>
1141 1142 1143
        since 0.9.11</span>
        Possible values for all *_limit parameters are in range from 0 to
        VIR_DOMAIN_MEMORY_PARAM_UNLIMITED.</dd>
1144 1145
      <dt><code>hard_limit</code></dt>
      <dd> The optional <code>hard_limit</code> element is the maximum memory
1146
        the guest can use. The units for this value are kibibytes (i.e. blocks
1147 1148 1149
        of 1024 bytes). Users of QEMU and KVM are strongly advised not to set
        this limit as domain may get killed by the kernel if the guess is too
        low, and determining the memory needed for a process to run is an
1150
        <a href="http://en.wikipedia.org/wiki/Undecidable_problem">
1151 1152 1153 1154 1155 1156 1157 1158
        undecidable problem</a>; that said, if you already set
        <code>locked</code> in
        <a href="#elementsMemoryBacking">memory backing</a> because your
        workload demands it, you'll have to take into account the specifics of
        your deployment and figure out a value for <code>hard_limit</code> that
        balances the risk of your guest being killed because the limit was set
        too low and the risk of your host crashing because it cannot reclaim
        the memory used by the guest due to <code>locked</code>. Good luck!</dd>
1159 1160 1161
      <dt><code>soft_limit</code></dt>
      <dd> The optional <code>soft_limit</code> element is the memory limit to
        enforce during memory contention. The units for this value are
1162
        kibibytes (i.e. blocks of 1024 bytes)</dd>
1163 1164 1165
      <dt><code>swap_hard_limit</code></dt>
      <dd> The optional <code>swap_hard_limit</code> element is the maximum
        memory plus swap the guest can use. The units for this value are
1166
        kibibytes (i.e. blocks of 1024 bytes). This has to be more than
1167 1168 1169 1170
        hard_limit value provided</dd>
      <dt><code>min_guarantee</code></dt>
      <dd> The optional <code>min_guarantee</code> element is the guaranteed
        minimum memory allocation for the guest. The units for this value are
1171 1172
        kibibytes (i.e. blocks of 1024 bytes). This element is only supported
        by VMware ESX and OpenVZ drivers.</dd>
1173 1174 1175
    </dl>


1176
    <h3><a id="elementsNUMATuning">NUMA Node Tuning</a></h3>
1177 1178 1179 1180 1181 1182

<pre>
&lt;domain&gt;
  ...
  &lt;numatune&gt;
    &lt;memory mode="strict" nodeset="1-4,^3"/&gt;
1183 1184
    &lt;memnode cellid="0" mode="strict" nodeset="1"/&gt;
    &lt;memnode cellid="2" mode="preferred" nodeset="2"/&gt;
1185 1186 1187 1188 1189 1190
  &lt;/numatune&gt;
  ...
&lt;/domain&gt;
</pre>

    <dl>
1191 1192 1193 1194 1195 1196
      <dt><code>numatune</code></dt>
      <dd>
        The optional <code>numatune</code> element provides details of
        how to tune the performance of a NUMA host via controlling NUMA policy
        for domain process. NB, only supported by QEMU driver.
        <span class='since'>Since 0.9.3</span>
1197
      </dd>
1198 1199
      <dt><code>memory</code></dt>
      <dd>
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        The optional <code>memory</code> element specifies how to allocate memory
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        for the domain process on a NUMA host. It contains several optional
        attributes. Attribute <code>mode</code> is either 'interleave',
        'strict', or 'preferred', defaults to 'strict'. Attribute
        <code>nodeset</code> specifies the NUMA nodes, using the same syntax as
        attribute <code>cpuset</code> of element <code>vcpu</code>. Attribute
        <code>placement</code> (<span class='since'>since 0.9.12</span>) can be
        used to indicate the memory placement mode for domain process, its value
        can be either "static" or "auto", defaults to <code>placement</code> of
        <code>vcpu</code>, or "static" if <code>nodeset</code> is specified.
        "auto" indicates the domain process will only allocate memory from the
        advisory nodeset returned from querying numad, and the value of attribute
        <code>nodeset</code> will be ignored if it's specified.

        If <code>placement</code> of <code>vcpu</code> is 'auto', and
        <code>numatune</code> is not specified, a default <code>numatune</code>
        with <code>placement</code> 'auto' and <code>mode</code> 'strict' will
        be added implicitly.

1219 1220
        <span class='since'>Since 0.9.3</span>
      </dd>
1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233
      <dt><code>memnode</code></dt>
      <dd>
        Optional <code>memnode</code> elements can specify memory allocation
        policies per each guest NUMA node.  For those nodes having no
        corresponding <code>memnode</code> element, the default from
        element <code>memory</code> will be used.  Attribute <code>cellid</code>
        addresses guest NUMA node for which the settings are applied.
        Attributes <code>mode</code> and <code>nodeset</code> have the same
        meaning and syntax as in <code>memory</code> element.

        This setting is not compatible with automatic placement.
        <span class='since'>QEMU Since 1.2.7</span>
      </dd>
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    </dl>

1236

1237
    <h3><a id="elementsBlockTuning">Block I/O Tuning</a></h3>
1238 1239 1240 1241 1242
<pre>
&lt;domain&gt;
  ...
  &lt;blkiotune&gt;
    &lt;weight&gt;800&lt;/weight&gt;
1243 1244 1245 1246 1247 1248 1249
    &lt;device&gt;
      &lt;path&gt;/dev/sda&lt;/path&gt;
      &lt;weight&gt;1000&lt;/weight&gt;
    &lt;/device&gt;
    &lt;device&gt;
      &lt;path&gt;/dev/sdb&lt;/path&gt;
      &lt;weight&gt;500&lt;/weight&gt;
1250 1251 1252 1253
      &lt;read_bytes_sec&gt;10000&lt;/read_bytes_sec&gt;
      &lt;write_bytes_sec&gt;10000&lt;/write_bytes_sec&gt;
      &lt;read_iops_sec&gt;20000&lt;/read_iops_sec&gt;
      &lt;write_iops_sec&gt;20000&lt;/write_iops_sec&gt;
1254
    &lt;/device&gt;
1255 1256 1257 1258 1259 1260 1261 1262 1263
  &lt;/blkiotune&gt;
  ...
&lt;/domain&gt;
</pre>

    <dl>
      <dt><code>blkiotune</code></dt>
      <dd> The optional <code>blkiotune</code> element provides the ability
        to tune Blkio cgroup tunable parameters for the domain. If this is
1264 1265
        omitted, it defaults to the OS provided
        defaults. <span class="since">Since 0.8.8</span></dd>
1266
      <dt><code>weight</code></dt>
1267 1268
      <dd> The optional <code>weight</code> element is the overall I/O
        weight of the guest. The value should be in the range [100,
1269 1270
        1000]. After kernel 2.6.39, the value could be in the
        range [10, 1000].</dd>
1271 1272 1273 1274 1275 1276 1277 1278
      <dt><code>device</code></dt>
      <dd>The domain may have multiple <code>device</code> elements
        that further tune the weights for each host block device in
        use by the domain.  Note that
        multiple <a href="#elementsDisks">guest disks</a> can share a
        single host block device, if they are backed by files within
        the same host file system, which is why this tuning parameter
        is at the global domain level rather than associated with each
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        guest disk device (contrast this to
        the <a href="#elementsDisks"><code>&lt;iotune&gt;</code></a>
        element which can apply to an
        individual <code>&lt;disk&gt;</code>).
        Each <code>device</code> element has two
1284 1285 1286
        mandatory sub-elements, <code>path</code> describing the
        absolute path of the device, and <code>weight</code> giving
        the relative weight of that device, in the range [100,
1287
        1000]. After kernel 2.6.39, the value could be in the
1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303
        range [10, 1000]. <span class="since">Since 0.9.8</span><br/>
        Additionally, the following optional sub-elements can be used:
        <dl>
          <dt><code>read_bytes_sec</code></dt>
          <dd>Read throughput limit in bytes per second.
            <span class="since">Since 1.2.2</span></dd>
          <dt><code>write_bytes_sec</code></dt>
          <dd>Write throughput limit in bytes per second.
            <span class="since">Since 1.2.2</span></dd>
          <dt><code>read_iops_sec</code></dt>
          <dd>Read I/O operations per second limit.
            <span class="since">Since 1.2.2</span></dd>
          <dt><code>write_iops_sec</code></dt>
          <dd>Write I/O operations per second limit.
            <span class="since">Since 1.2.2</span></dd>
      </dl></dd></dl>
1304 1305


1306
    <h3><a id="resPartition">Resource partitioning</a></h3>
1307 1308 1309 1310 1311 1312

    <p>
      Hypervisors may allow for virtual machines to be placed into
      resource partitions, potentially with nesting of said partitions.
      The <code>resource</code> element groups together configuration
      related to resource partitioning. It currently supports a child
1313
      element <code>partition</code> whose content defines the absolute path
1314 1315 1316 1317 1318 1319 1320 1321
      of the resource partition in which to place the domain. If no
      partition is listed, then the domain will be placed in a default
      partition. It is the responsibility of the app/admin to ensure
      that the partition exists prior to starting the guest. Only the
      (hypervisor specific) default partition can be assumed to exist
      by default.
    </p>
<pre>
1322 1323 1324 1325 1326
...
&lt;resource&gt;
  &lt;partition&gt;/virtualmachines/production&lt;/partition&gt;
&lt;/resource&gt;
...
1327 1328 1329 1330
</pre>

    <p>
      Resource partitions are currently supported by the QEMU and
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      LXC drivers, which map partition paths to cgroups directories,
1332 1333 1334
      in all mounted controllers. <span class="since">Since 1.0.5</span>
    </p>

1335
    <h3><a id="elementsCPU">CPU model and topology</a></h3>
1336 1337 1338 1339 1340 1341 1342

    <p>
      Requirements for CPU model, its features and topology can be specified
      using the following collection of elements.
      <span class="since">Since 0.7.5</span>
    </p>

1343
<pre>
1344 1345 1346 1347 1348
...
&lt;cpu match='exact'&gt;
  &lt;model fallback='allow'&gt;core2duo&lt;/model&gt;
  &lt;vendor&gt;Intel&lt;/vendor&gt;
  &lt;topology sockets='1' cores='2' threads='1'/&gt;
1349
  &lt;cache level='3' mode='emulate'/&gt;
1350 1351 1352
  &lt;feature policy='disable' name='lahf_lm'/&gt;
&lt;/cpu&gt;
...</pre>
1353

1354
<pre>
1355 1356 1357 1358 1359
&lt;cpu mode='host-model'&gt;
  &lt;model fallback='forbid'/&gt;
  &lt;topology sockets='1' cores='2' threads='1'/&gt;
&lt;/cpu&gt;
...</pre>
1360 1361

<pre>
1362
&lt;cpu mode='host-passthrough'&gt;
1363
  &lt;cache mode='passthrough'/&gt;
1364 1365
  &lt;feature policy='disable' name='lahf_lm'/&gt;
...</pre>
1366

1367 1368 1369 1370 1371 1372
    <p>
      In case no restrictions need to be put on CPU model and its features, a
      simpler <code>cpu</code> element can be used.
      <span class="since">Since 0.7.6</span>
    </p>

1373
<pre>
1374 1375 1376 1377 1378
...
&lt;cpu&gt;
  &lt;topology sockets='1' cores='2' threads='1'/&gt;
&lt;/cpu&gt;
...</pre>
1379 1380 1381 1382

    <dl>
      <dt><code>cpu</code></dt>
      <dd>The <code>cpu</code> element is the main container for describing
1383 1384
        guest CPU requirements. Its <code>match</code> attribute specifies how
        strictly the virtual CPU provided to the guest matches these
1385 1386 1387 1388 1389 1390 1391 1392
        requirements. <span class="since">Since 0.7.6</span> the
        <code>match</code> attribute can be omitted if <code>topology</code>
        is the only element within <code>cpu</code>. Possible values for the
        <code>match</code> attribute are:

        <dl>
          <dt><code>minimum</code></dt>
          <dd>The specified CPU model and features describes the minimum
1393 1394 1395 1396 1397 1398
            requested CPU. A better CPU will be provided to the guest if it
            is possible with the requested hypervisor on the current host.
            This is a constrained <code>host-model</code> mode; the domain
            will not be created if the provided virtual CPU does not meet
            the requirements.</dd>

1399
          <dt><code>exact</code></dt>
1400 1401 1402 1403
          <dd>The virtual CPU provided to the guest should exactly match the
            specification. If such CPU is not supported, libvirt will refuse
            to start the domain.</dd>

1404
          <dt><code>strict</code></dt>
1405 1406 1407
          <dd>The domain will not be created unless the host CPU exactly
            matches the specification. This is not very useful in practice
            and should only be used if there is a real reason.</dd>
1408
        </dl>
1409

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        <span class="since">Since 0.8.5</span> the <code>match</code>
        attribute can be omitted and will default to <code>exact</code>.
1412

1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442
        Sometimes the hypervisor is not able to create a virtual CPU exactly
        matching the specification passed by libvirt.
        <span class="since">Since 3.2.0</span>, an optional <code>check</code>
        attribute can be used to request a specific way of checking whether
        the virtual CPU matches the specification. It is usually safe to omit
        this attribute when starting a domain and stick with the default
        value. Once the domain starts, libvirt will automatically change the
        <code>check</code> attribute to the best supported value to ensure the
        virtual CPU does not change when the domain is migrated to another
        host. The following values can be used:

        <dl>
          <dt><code>none</code></dt>
          <dd>Libvirt does no checking and it is up to the hypervisor to
            refuse to start the domain if it cannot provide the requested CPU.
            With QEMU this means no checking is done at all since the default
            behavior of QEMU is to emit warnings, but start the domain anyway.
          </dd>

          <dt><code>partial</code></dt>
          <dd>Libvirt will check the guest CPU specification before starting
            a domain, but the rest is left on the hypervisor. It can still
            provide a different virtual CPU.</dd>

          <dt><code>full</code></dt>
          <dd>The virtual CPU created by the hypervisor will be checked
            against the CPU specification and the domain will not be started
            unless the two CPUs match.</dd>
        </dl>

1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459
        <span class="since">Since 0.9.10</span>, an optional <code>mode</code>
        attribute may be used to make it easier to configure a guest CPU to be
        as close to host CPU as possible. Possible values for the
        <code>mode</code> attribute are:

        <dl>
          <dt><code>custom</code></dt>
          <dd>In this mode, the <code>cpu</code> element describes the CPU
          that should be presented to the guest. This is the default when no
          <code>mode</code> attribute is specified. This mode makes it so that
          a persistent guest will see the same hardware no matter what host
          the guest is booted on.</dd>
          <dt><code>host-model</code></dt>
          <dd>The <code>host-model</code> mode is essentially a shortcut to
          copying host CPU definition from capabilities XML into domain XML.
          Since the CPU definition is copied just before starting a domain,
          exactly the same XML can be used on different hosts while still
1460 1461 1462 1463 1464 1465 1466 1467 1468
          providing the best guest CPU each host supports. The
          <code>match</code> attribute can't be used in this mode. Specifying
          CPU model is not supported either, but <code>model</code>'s
          <code>fallback</code> attribute may still be used. Using the
          <code>feature</code> element, specific flags may be enabled or
          disabled specifically in addition to the host model. This may be
          used to fine tune features that can be emulated.
          <span class="since">(Since 1.1.1)</span>.
          Libvirt does not model every aspect of each CPU so
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          the guest CPU will not match the host CPU exactly. On the other
          hand, the ABI provided to the guest is reproducible. During
          migration, complete CPU model definition is transferred to the
          destination host so the migrated guest will see exactly the same CPU
          model even if the destination host contains more capable CPUs for
          the running instance of the guest; but shutting down and restarting
          the guest may present different hardware to the guest according to
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          the capabilities of the new host. Prior to libvirt 3.2.0 and QEMU
          2.9.0 detection of the host CPU model via QEMU is not supported.
          Thus the CPU configuration created using <code>host-model</code>
          may not work as expected.
          <span class="since">Since 3.2.0 and QEMU 2.9.0</span> this mode
          works the way it was designed and it is indicated by the
          <code>fallback</code> attribute set to <code>forbid</code> in the
          host-model CPU definition advertised in
          <a href="formatdomaincaps.html#elementsCPU">domain capabilities XML</a>.
          When <code>fallback</code> attribute is set to <code>allow</code>
          in the domain capabilities XML, it is recommended to use
          <code>custom</code> mode with just the CPU model from the host
          capabilities XML. <span class="since">Since 1.2.11</span> PowerISA
          allows processors to run VMs in binary compatibility mode supporting
          an older version of ISA.  Libvirt on PowerPC architecture uses the
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          <code>host-model</code> to signify a guest mode CPU running in
          binary compatibility mode. Example:
          When a user needs a power7 VM to run in compatibility mode
          on a Power8 host, this can be described in XML as follows :
<pre>
1496 1497 1498 1499
&lt;cpu mode='host-model'&gt;
  &lt;model&gt;power7&lt;/model&gt;
&lt;/cpu&gt;
...</pre>
1500
          </dd>
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          <dt><code>host-passthrough</code></dt>
          <dd>With this mode, the CPU visible to the guest should be exactly
          the same as the host CPU even in the aspects that libvirt does not
          understand. Though the downside of this mode is that the guest
          environment cannot be reproduced on different hardware. Thus, if you
1506
          hit any bugs, you are on your own. Further details of that CPU can
1507 1508 1509 1510 1511
          be changed using <code>feature</code> elements. Migration of a guest
          using host-passthrough is dangerous if the source and destination
          hosts are not identical in both hardware and configuration. If such
          a migration is attempted then the guest may hang or crash upon
          resuming execution on the destination host.</dd>
1512
        </dl>
1513 1514 1515 1516 1517 1518 1519 1520 1521

        Both <code>host-model</code> and <code>host-passthrough</code> modes
        make sense when a domain can run directly on the host CPUs (for
        example, domains with type <code>kvm</code>). The actual host CPU is
        irrelevant for domains with emulated virtual CPUs (such as domains with
        type <code>qemu</code>). However, for backward compatibility
        <code>host-model</code> may be implemented even for domains running on
        emulated CPUs in which case the best CPU the hypervisor is able to
        emulate may be used rather then trying to mimic the host CPU model.
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      </dd>

      <dt><code>model</code></dt>
      <dd>The content of the <code>model</code> element specifies CPU model
        requested by the guest. The list of available CPU models and their
        definition can be found in <code>cpu_map.xml</code> file installed
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        in libvirt's data directory. If a hypervisor is not able to use the
        exact CPU model, libvirt automatically falls back to a closest model
        supported by the hypervisor while maintaining the list of CPU
        features. <span class="since">Since 0.9.10</span>, an optional
        <code>fallback</code> attribute can be used to forbid this behavior,
        in which case an attempt to start a domain requesting an unsupported
        CPU model will fail. Supported values for <code>fallback</code>
        attribute are: <code>allow</code> (this is the default), and
1536
        <code>forbid</code>. The optional <code>vendor_id</code> attribute
1537
        (<span class="since">Since 0.10.0</span>)  can be used to set the
1538 1539 1540
        vendor id seen by the guest. It must be exactly 12 characters long.
        If not set the vendor id of the host is used. Typical possible
        values are "AuthenticAMD" and "GenuineIntel".</dd>
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      <dt><code>vendor</code></dt>
      <dd><span class="since">Since 0.8.3</span> the content of the
        <code>vendor</code> element specifies CPU vendor requested by the
        guest. If this element is missing, the guest can be run on a CPU
        matching given features regardless on its vendor. The list of
        supported vendors can be found in <code>cpu_map.xml</code>.</dd>

1549 1550 1551 1552 1553
      <dt><code>topology</code></dt>
      <dd>The <code>topology</code> element specifies requested topology of
        virtual CPU provided to the guest. Three non-zero values have to be
        given for <code>sockets</code>, <code>cores</code>, and
        <code>threads</code>: total number of CPU sockets, number of cores per
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        socket, and number of threads per core, respectively. Hypervisors may
        require that the maximum number of vCPUs specified by the
        <code>cpus</code> element equals to the number of vcpus resulting
        from the topology.</dd>
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      <dt><code>feature</code></dt>
      <dd>The <code>cpu</code> element can contain zero or more
        <code>elements</code> used to fine-tune features provided by the
        selected CPU model. The list of known feature names can be found in
        the same file as CPU models. The meaning of each <code>feature</code>
        element depends on its <code>policy</code> attribute, which has to be
        set to one of the following values:

        <dl>
          <dt><code>force</code></dt>
          <dd>The virtual CPU will claim the feature is supported regardless
            of it being supported by host CPU.</dd>
          <dt><code>require</code></dt>
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          <dd>Guest creation will fail unless the feature is supported by the
            host CPU or the hypervisor is able to emulate it.</dd>
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          <dt><code>optional</code></dt>
          <dd>The feature will be supported by virtual CPU if and only if it
            is supported by host CPU.</dd>
          <dt><code>disable</code></dt>
          <dd>The feature will not be supported by virtual CPU.</dd>
          <dt><code>forbid</code></dt>
          <dd>Guest creation will fail if the feature is supported by host
            CPU.</dd>
        </dl>
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        <span class="since">Since 0.8.5</span> the <code>policy</code>
        attribute can be omitted and will default to <code>require</code>.
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        <p> Individual CPU feature names are specified as part of the
        <code>name</code> attribute. For example, to explicitly specify
        the 'pcid' feature with Intel IvyBridge CPU model:
        </p>

<pre>
...
&lt;cpu match='exact'&gt;
  &lt;model fallback='forbid'&gt;IvyBridge&lt;/model&gt;
  &lt;vendor&gt;Intel&lt;/vendor&gt;
  &lt;feature policy='require' name='pcid'/&gt;
&lt;/cpu&gt;
...</pre>

1601
      </dd>
1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634

      <dt><code>cache</code></dt>
      <dd><span class="since">Since 3.3.0</span> the <code>cache</code>
        element describes the virtual CPU cache. If the element is missing,
        the hypervisor will use a sensible default.

        <dl>
          <dt><code>level</code></dt>
          <dd>This optional attribute specifies which cache level is described
            by the element. Missing attribute means the element describes all
            CPU cache levels at once. Mixing <code>cache</code> elements with
            the <code>level</code> attribute set and those without the
            attribute is forbidden.</dd>

          <dt><code>mode</code></dt>
          <dd>
            The following values are supported:
            <dl>
              <dt><code>emulate</code></dt>
              <dd>The hypervisor will provide a fake CPU cache data.</dd>

              <dt><code>passthrough</code></dt>
              <dd>The real CPU cache data reported by the host CPU will be
                passed through to the virtual CPU.</dd>

              <dt><code>disable</code></dt>
              <dd>The virtual CPU will report no CPU cache of the specified
                level (or no cache at all if the <code>level</code> attribute
                is missing).</dd>
            </dl>
          </dd>
        </dl>
      </dd>
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    </dl>

1637
    <p>
1638
      Guest NUMA topology can be specified using the <code>numa</code> element.
1639 1640 1641 1642
      <span class="since">Since 0.9.8</span>
    </p>

<pre>
1643 1644
...
&lt;cpu&gt;
1645
  ...
1646
  &lt;numa&gt;
1647
    &lt;cell id='0' cpus='0-3' memory='512000' unit='KiB' discard='yes'/&gt;
1648 1649 1650 1651 1652
    &lt;cell id='1' cpus='4-7' memory='512000' unit='KiB' memAccess='shared'/&gt;
  &lt;/numa&gt;
  ...
&lt;/cpu&gt;
...</pre>
1653 1654 1655

    <p>
      Each <code>cell</code> element specifies a NUMA cell or a NUMA node.
1656 1657 1658
      <code>cpus</code> specifies the CPU or range of CPUs that are
      part of the node. <code>memory</code> specifies the node memory
      in kibibytes (i.e. blocks of 1024 bytes).
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      <span class="since">Since 1.2.11</span> one can use an additional <a
          href="#elementsMemoryAllocation"><code>unit</code></a> attribute to
      define units in which <code>memory</code> is specified.
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      <span class="since">Since 1.2.7</span> all cells should
      have <code>id</code> attribute in case referring to some cell is
      necessary in the code, otherwise the cells are
      assigned <code>id</code>s in the increasing order starting from
      0.  Mixing cells with and without the <code>id</code> attribute
      is not recommended as it may result in unwanted behaviour.
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      <span class='since'>Since 1.2.9</span> the optional attribute
      <code>memAccess</code> can control whether the memory is to be
      mapped as "shared" or "private".  This is valid only for
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      hugepages-backed memory and nvdimm modules.
1673 1674 1675 1676 1677 1678 1679

      Each <code>cell</code> element can have an optional
      <code>discard</code> attribute which fine tunes the discard
      feature for given numa node as described under
      <a href="#elementsMemoryBacking">Memory Backing</a>.
      Accepted values are <code>yes</code> and <code>no</code>.
      <span class='since'>Since 4.4.0</span>
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    </p>

    <p>
1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742
      This guest NUMA specification is currently available only for
      QEMU/KVM and Xen.
    </p>

    <p>
      A NUMA hardware architecture supports the notion of distances
      between NUMA cells. <span class="since">Since 3.10.0</span> it
      is possible to define the distance between NUMA cells using the
      <code>distances</code> element within a NUMA <code>cell</code>
      description. The <code>sibling</code> sub-element is used to
      specify the distance value between sibling NUMA cells. For more
      details, see the chapter explaining the system's SLIT (System
      Locality Information Table) within the ACPI (Advanced
      Configuration and Power Interface) specification.
    </p>

<pre>
...
&lt;cpu&gt;
  ...
  &lt;numa&gt;
    &lt;cell id='0' cpus='0,4-7' memory='512000' unit='KiB'&gt;
      &lt;distances&gt;
        &lt;sibling id='0' value='10'/&gt;
        &lt;sibling id='1' value='21'/&gt;
        &lt;sibling id='2' value='31'/&gt;
        &lt;sibling id='3' value='41'/&gt;
      &lt;/distances&gt;
    &lt;/cell&gt;
    &lt;cell id='1' cpus='1,8-10,12-15' memory='512000' unit='KiB' memAccess='shared'&gt;
      &lt;distances&gt;
        &lt;sibling id='0' value='21'/&gt;
        &lt;sibling id='1' value='10'/&gt;
        &lt;sibling id='2' value='21'/&gt;
        &lt;sibling id='3' value='31'/&gt;
      &lt;/distances&gt;
    &lt;/cell&gt;
    &lt;cell id='2' cpus='2,11' memory='512000' unit='KiB' memAccess='shared'&gt;
      &lt;distances&gt;
        &lt;sibling id='0' value='31'/&gt;
        &lt;sibling id='1' value='21'/&gt;
        &lt;sibling id='2' value='10'/&gt;
        &lt;sibling id='3' value='21'/&gt;
      &lt;/distances&gt;
    &lt;/cell&gt;
    &lt;cell id='3' cpus='3' memory='512000' unit='KiB'&gt;
      &lt;distances&gt;
        &lt;sibling id='0' value='41'/&gt;
        &lt;sibling id='1' value='31'/&gt;
        &lt;sibling id='2' value='21'/&gt;
        &lt;sibling id='3' value='10'/&gt;
      &lt;/distances&gt;
    &lt;/cell&gt;
  &lt;/numa&gt;
  ...
&lt;/cpu&gt;
...</pre>

    <p>
      Describing distances between NUMA cells is currently only supported
1743
      by Xen and QEMU. If no <code>distances</code> are given to describe
1744 1745
      the SLIT data between different cells, it will default to a scheme
      using 10 for local and 20 for remote distances.
1746 1747
    </p>

1748
    <h3><a id="elementsEvents">Events configuration</a></h3>
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    <p>
A
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      It is sometimes necessary to override the default actions taken
1752 1753
      on various events. Not all hypervisors support all events and actions.
      The actions may be taken as a result of calls to libvirt APIs
1754 1755 1756 1757 1758 1759 1760 1761 1762 1763
      <a href="html/libvirt-libvirt-domain.html#virDomainReboot">
        <code>virDomainReboot</code>
      </a>,
      <a href="html/libvirt-libvirt-domain.html#virDomainShutdown">
        <code>virDomainShutdown</code>
      </a>,
      or
      <a href="html/libvirt-libvirt-domain.html#virDomainShutdownFlags">
        <code>virDomainShutdownFlags</code>
      </a>.
1764 1765
      Using <code>virsh reboot</code> or <code>virsh shutdown</code> would
      also trigger the event.
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    </p>

1768
<pre>
1769 1770 1771 1772 1773 1774
...
&lt;on_poweroff&gt;destroy&lt;/on_poweroff&gt;
&lt;on_reboot&gt;restart&lt;/on_reboot&gt;
&lt;on_crash&gt;restart&lt;/on_crash&gt;
&lt;on_lockfailure&gt;poweroff&lt;/on_lockfailure&gt;
...</pre>
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1776 1777 1778 1779 1780 1781 1782
    <p>
      The following collections of elements allow the actions to be
      specified when a guest OS triggers a lifecycle operation. A
      common use case is to force a reboot to be treated as a poweroff
      when doing the initial OS installation. This allows the VM to be
      re-configured for the first post-install bootup.
    </p>
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    <dl>
      <dt><code>on_poweroff</code></dt>
      <dd>The content of this element specifies the action to take when
M
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        the guest requests a poweroff.</dd>
D
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      <dt><code>on_reboot</code></dt>
D
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1788
      <dd>The content of this element specifies the action to take when
M
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        the guest requests a reboot.</dd>
D
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1790
      <dt><code>on_crash</code></dt>
D
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1791
      <dd>The content of this element specifies the action to take when
M
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        the guest crashes.</dd>
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    </dl>

    <p>
      Each of these states allow for the same four possible actions.
    </p>

    <dl>
      <dt><code>destroy</code></dt>
      <dd>The domain will be terminated completely and all resources
1802
        released.</dd>
D
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1803
      <dt><code>restart</code></dt>
1804 1805
      <dd>The domain will be terminated and then restarted with
        the same configuration.</dd>
D
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1806
      <dt><code>preserve</code></dt>
1807
      <dd>The domain will be terminated and its resource preserved
M
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1808
        to allow analysis.</dd>
D
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1809
      <dt><code>rename-restart</code></dt>
1810 1811
      <dd>The domain will be terminated and then restarted with
        a new name.</dd>
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    </dl>

1814
    <p>
1815 1816 1817 1818 1819 1820 1821 1822 1823 1824
    QEMU/KVM supports the <code>on_poweroff</code> and <code>on_reboot</code>
    events handling the <code>destroy</code> and <code>restart</code> actions.
    The <code>preserve</code> action for an <code>on_reboot</code> event
    is treated as a <code>destroy</code> and the <code>rename-restart</code>
    action for an <code>on_poweroff</code> event is treated as a
    <code>restart</code> event.
    </p>

    <p>
      The <code>on_crash</code> event supports these additional
1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837
      actions <span class="since">since 0.8.4</span>.
    </p>

    <dl>
      <dt><code>coredump-destroy</code></dt>
      <dd>The crashed domain's core will be dumped, and then the
        domain will be terminated completely and all resources
        released</dd>
      <dt><code>coredump-restart</code></dt>
      <dd>The crashed domain's core will be dumped, and then the
        domain will be restarted with the same configuration</dd>
    </dl>

1838 1839 1840 1841 1842 1843 1844
    <p>
      <span class="since">Since 3.9.0</span>, the lifecycle events can
      be configured via the
      <a href="html/libvirt-libvirt-domain.html#virDomainSetLifecycleAction">
        <code>virDomainSetLifecycleAction</code></a> API.
    </p>

1845 1846
    <p>
      The <code>on_lockfailure</code> element (<span class="since">since
1847
      1.0.0</span>) may be used to configure what action should be
1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865
      taken when a lock manager loses resource locks. The following
      actions are recognized by libvirt, although not all of them need
      to be supported by individual lock managers. When no action is
      specified, each lock manager will take its default action.
    </p>
    <dl>
      <dt><code>poweroff</code></dt>
      <dd>The domain will be forcefully powered off.</dd>
      <dt><code>restart</code></dt>
      <dd>The domain will be powered off and started up again to
        reacquire its locks.</dd>
      <dt><code>pause</code></dt>
      <dd>The domain will be paused so that it can be manually resumed
        when lock issues are solved.</dd>
      <dt><code>ignore</code></dt>
      <dd>Keep the domain running as if nothing happened.</dd>
    </dl>

1866
    <h3><a id="elementsPowerManagement">Power Management</a></h3>
1867 1868 1869 1870 1871 1872 1873 1874

    <p>
      <span class="since">Since 0.10.2</span> it is possible to
      forcibly enable or disable BIOS advertisements to the guest
      OS. (NB: Only qemu driver support)
    </p>

<pre>
1875 1876 1877 1878 1879 1880
...
&lt;pm&gt;
  &lt;suspend-to-disk enabled='no'/&gt;
  &lt;suspend-to-mem enabled='yes'/&gt;
&lt;/pm&gt;
...</pre>
1881 1882 1883 1884

    <dl>
      <dt><code>pm</code></dt>
      <dd>These elements enable ('yes') or disable ('no') BIOS support
1885
        for S3 (suspend-to-mem) and S4 (suspend-to-disk) ACPI sleep
1886
        states. If nothing is specified, then the hypervisor will be
1887 1888 1889 1890 1891
        left with its default value.<br/>
        Note: This setting cannot prevent the guest OS from performing
        a suspend as the guest OS itself can choose to circumvent the
        unavailability of the sleep states (e.g. S4 by turning off
        completely).</dd>
1892 1893
    </dl>

1894
    <h3><a id="elementsFeatures">Hypervisor features</a></h3>
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    <p>
      Hypervisors may allow certain CPU / machine features to be
      toggled on/off.
    </p>

1901
<pre>
1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923
...
&lt;features&gt;
  &lt;pae/&gt;
  &lt;acpi/&gt;
  &lt;apic/&gt;
  &lt;hap/&gt;
  &lt;privnet/&gt;
  &lt;hyperv&gt;
    &lt;relaxed state='on'/&gt;
    &lt;vapic state='on'/&gt;
    &lt;spinlocks state='on' retries='4096'/&gt;
    &lt;vpindex state='on'/&gt;
    &lt;runtime state='on'/&gt;
    &lt;synic state='on'/&gt;
    &lt;reset state='on'/&gt;
    &lt;vendor_id state='on' value='KVM Hv'/&gt;
  &lt;/hyperv&gt;
  &lt;kvm&gt;
    &lt;hidden state='on'/&gt;
  &lt;/kvm&gt;
  &lt;pvspinlock state='on'/&gt;
  &lt;gic version='2'/&gt;
1924
  &lt;ioapic driver='qemu'/&gt;
1925
  &lt;hpt resizing='required'/&gt;
1926
  &lt;vmcoreinfo state='on'/&gt;
1927 1928 1929
  &lt;smm state='on'&gt;
    &lt;tseg unit='MiB'&gt;48&lt;/tseg&gt;
  &lt;/smm&gt;
1930 1931
&lt;/features&gt;
...</pre>
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    <p>
      All features are listed within the <code>features</code>
      element, omitting a togglable feature tag turns it off.
      The available features can be found by asking
1937 1938
      for the <a href="formatcaps.html">capabilities XML</a> and
      <a href="formatdomaincaps.html">domain capabilities XML</a>,
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      but a common set for fully virtualized domains are:
    </p>

    <dl>
      <dt><code>pae</code></dt>
      <dd>Physical address extension mode allows 32-bit guests
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        to address more than 4 GB of memory.</dd>
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      <dt><code>acpi</code></dt>
      <dd>ACPI is useful for power management, for example, with
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        KVM guests it is required for graceful shutdown to work.
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      </dd>
1950 1951
      <dt><code>apic</code></dt>
      <dd>APIC allows the use of programmable IRQ
1952 1953 1954
      management. <span class="since">Since 0.10.2 (QEMU only)</span> there is
      an optional attribute <code>eoi</code> with values <code>on</code>
      and <code>off</code> which toggles the availability of EOI (End of
1955 1956
      Interrupt) for the guest.
      </dd>
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      <dt><code>hap</code></dt>
1958 1959 1960 1961
      <dd>Depending on the <code>state</code> attribute (values <code>on</code>,
        <code>off</code>) enable or disable use of Hardware Assisted Paging.
        The default is <code>on</code> if the hypervisor detects availability
        of Hardware Assisted Paging.
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      </dd>
1963 1964 1965 1966
      <dt><code>viridian</code></dt>
      <dd>Enable Viridian hypervisor extensions for paravirtualizing
        guest operating systems
      </dd>
1967 1968 1969 1970 1971 1972
      <dt><code>privnet</code></dt>
      <dd>Always create a private network namespace. This is
        automatically set if any interface devices are defined.
        This feature is only relevant for container based
        virtualization drivers, such as LXC.
      </dd>
1973 1974 1975 1976 1977 1978 1979 1980
      <dt><code>hyperv</code></dt>
      <dd>Enable various features improving behavior of guests
        running Microsoft Windows.
      <table class="top_table">
        <tr>
          <th>Feature</th>
          <th>Description</th>
          <th>Value</th>
1981
          <th>Since</th>
1982 1983 1984
        </tr>
        <tr>
          <td>relaxed</td>
1985
          <td>Relax constraints on timers</td>
1986
          <td> on, off</td>
1987
          <td><span class="since">1.0.0 (QEMU 2.0)</span></td>
1988 1989 1990 1991 1992
        </tr>
        <tr>
          <td>vapic</td>
          <td>Enable virtual APIC</td>
          <td>on, off</td>
1993
          <td><span class="since">1.1.0 (QEMU 2.0)</span></td>
1994 1995 1996 1997 1998
        </tr>
        <tr>
          <td>spinlocks</td>
          <td>Enable spinlock support</td>
          <td>on, off; retries - at least 4095</td>
1999
          <td><span class="since">1.1.0 (QEMU 2.0)</span></td>
2000
        </tr>
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
        <tr>
          <td>vpindex</td>
          <td>Virtual processor index</td>
          <td> on, off</td>
          <td><span class="since">1.3.3 (QEMU 2.5)</span></td>
        </tr>
        <tr>
          <td>runtime</td>
          <td>Processor time spent on running guest code and on behalf of guest code</td>
          <td> on, off</td>
          <td><span class="since">1.3.3 (QEMU 2.5)</span></td>
        </tr>
        <tr>
          <td>synic</td>
          <td>Enable Synthetic Interrupt Controller (SyNIC)</td>
          <td> on, off</td>
2017
          <td><span class="since">1.3.3 (QEMU 2.6)</span></td>
2018 2019 2020 2021 2022
        </tr>
        <tr>
          <td>stimer</td>
          <td>Enable SyNIC timers</td>
          <td> on, off</td>
2023
          <td><span class="since">1.3.3 (QEMU 2.6)</span></td>
2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036
        </tr>
        <tr>
          <td>reset</td>
          <td>Enable hypervisor reset</td>
          <td> on, off</td>
          <td><span class="since">1.3.3 (QEMU 2.5)</span></td>
        </tr>
        <tr>
          <td>vendor_id</td>
          <td>Set hypervisor vendor id</td>
          <td>on, off; value - string, up to 12 characters</td>
          <td><span class="since">1.3.3 (QEMU 2.5)</span></td>
        </tr>
2037 2038
      </table>
      </dd>
2039 2040 2041 2042 2043 2044
      <dt><code>pvspinlock</code></dt>
      <dd>Notify the guest that the host supports paravirtual spinlocks
          for example by exposing the pvticketlocks mechanism. This feature
          can be explicitly disabled by using <code>state='off'</code>
          attribute.
      </dd>
2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057
      <dt><code>kvm</code></dt>
      <dd>Various features to change the behavior of the KVM hypervisor.
      <table class="top_table">
        <tr>
          <th>Feature</th>
          <th>Description</th>
          <th>Value</th>
          <th>Since</th>
        </tr>
        <tr>
          <td>hidden</td>
          <td>Hide the KVM hypervisor from standard MSR based discovery</td>
          <td>on, off</td>
2058
          <td><span class="since">1.2.8 (QEMU 2.1.0)</span></td>
2059 2060 2061
        </tr>
      </table>
      </dd>
2062 2063 2064 2065 2066 2067
      <dt><code>pmu</code></dt>
      <dd>Depending on the <code>state</code> attribute (values <code>on</code>,
        <code>off</code>, default <code>on</code>) enable or disable the
        performance monitoring unit for the guest.
        <span class="since">Since 1.2.12</span>
      </dd>
2068 2069 2070
      <dt><code>vmport</code></dt>
      <dd>Depending on the <code>state</code> attribute (values <code>on</code>,
        <code>off</code>, default <code>on</code>) enable or disable
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        the emulation of VMware IO port, for vmmouse etc.
2072 2073
        <span class="since">Since 1.2.16</span>
      </dd>
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      <dt><code>gic</code></dt>
      <dd>Enable for architectures using a General Interrupt
          Controller instead of APIC in order to handle interrupts.
          For example, the 'aarch64' architecture uses
          <code>gic</code> instead of <code>apic</code>. The optional
          attribute <code>version</code> specifies the GIC version;
2080 2081 2082
          however, it may not be supported by all hypervisors. Accepted
          values are <code>2</code>, <code>3</code> and <code>host</code>.
          <span class="since">Since 1.2.16</span>
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      </dd>
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      <dt><code>smm</code></dt>
2085 2086 2087
      <dd>
        <p>
          Depending on the <code>state</code> attribute (values <code>on</code>,
2088 2089
          <code>off</code>, default <code>on</code>) enable or disable
          System Management Mode.
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          <span class="since">Since 2.1.0</span>
2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133
        </p><p> Optional sub-element <code>tseg</code> can be used to specify
          the amount of memory dedicated to SMM's extended TSEG. That offers a
          fourth option size apart from the existing ones (1 MiB, 2 MiB and 8
          MiB) that the guest OS (or rather loader) can choose from. The size
          can be specified as a value of that element, optional attribute
          <code>unit</code> can be used to specify the unit of the
          aforementioned value (defaults to 'MiB').  If set to 0 the extended
          size is not advertised and only the default ones (see above) are
          available.
        </p><p>
          <b>If the VM is booting you should leave this option alone, unless you
          are very certain you know what you are doing.</b>
        </p><p>
          This value is configurable due to the fact that the calculation cannot
          be done right with the guarantee that it will work correctly.  In
          QEMU, the user-configurable extended TSEG feature was unavailable up
          to and including <code>pc-q35-2.9</code>. Starting with
          <code>pc-q35-2.10</code> the feature is available, with default size
          16 MiB.  That should suffice for up to roughly 272 VCPUs, 5 GiB guest
          RAM in total, no hotplug memory range, and 32 GiB of 64-bit PCI MMIO
          aperture.  Or for 48 VCPUs, with 1TB of guest RAM, no hotplug DIMM
          range, and 32GB of 64-bit PCI MMIO aperture. The values may also vary
          based on the loader the VM is using.
        </p><p>
          Additional size might be needed for significantly higher VCPU counts
          or increased address space (that can be memory, maxMemory, 64-bit PCI
          MMIO aperture size; roughly 8 MiB of TSEG per 1 TiB of address space)
          which can also be rounded up.
        </p><p>
          Due to the nature of this setting being similar to "how much RAM
          should the guest have" users are advised to either consult the
          documentation of the guest OS or loader (if there is any), or test
          this by trial-and-error changing the value until the VM boots
          successfully.  Yet another guiding value for users might be the fact
          that 48 MiB should be enough for pretty large guests (240 VCPUs and
          4TB guest RAM), but it is on purpose not set as default as 48 MiB of
          unavailable RAM might be too much for small guests (e.g. with 512 MiB
          of RAM).
        </p><p>
          See <a href="#elementsMemoryAllocation">Memory Allocation</a>
          for more details about the <code>unit</code> attribute.
          <span class="since">Since 4.5.0</span> (QEMU only)
        </p>
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      </dd>
2135 2136 2137 2138 2139 2140 2141 2142
      <dt><code>ioapic</code></dt>
      <dd>Tune the I/O APIC. Possible values for the
          <code>driver</code> attribute are:
          <code>kvm</code> (default for KVM domains)
          and <code>qemu</code> which puts I/O APIC in userspace
          which is also known as a split I/O APIC mode.
          <span class="since">Since 3.4.0</span> (QEMU/KVM only)
      </dd>
2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153
      <dt><code>hpt</code></dt>
      <dd>Configure the HPT (Hash Page Table) of a pSeries guest. Possible
          values for the <code>resizing</code> attribute are
          <code>enabled</code>, which causes HPT resizing to be enabled if
          both the guest and the host support it; <code>disabled</code>, which
          causes HPT resizing to be disabled regardless of guest and host
          support; and <code>required</code>, which prevents the guest from
          starting unless both the guest and the host support HPT resizing. If
          the attribute is not defined, the hypervisor default will be used.
          <span class="since">Since 3.10.0</span> (QEMU/KVM only)
      </dd>
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      <dt><code>vmcoreinfo</code></dt>
      <dd>Enable QEMU vmcoreinfo device to let the guest kernel save debug
2156
          details. <span class="since">Since 4.4.0</span> (QEMU only)
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      </dd>
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    </dl>

2160
    <h3><a id="elementsTime">Time keeping</a></h3>
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    <p>
      The guest clock is typically initialized from the host clock.
      Most operating systems expect the hardware clock to be kept
      in UTC, and this is the default. Windows, however, expects
      it to be in so called 'localtime'.
    </p>

2169
<pre>
2170 2171 2172 2173 2174 2175 2176 2177
...
&lt;clock offset='localtime'&gt;
  &lt;timer name='rtc' tickpolicy='catchup' track='guest'&gt;
    &lt;catchup threshold='123' slew='120' limit='10000'/&gt;
  &lt;/timer&gt;
  &lt;timer name='pit' tickpolicy='delay'/&gt;
&lt;/clock&gt;
...</pre>
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    <dl>
      <dt><code>clock</code></dt>
2181
      <dd>
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        <p>The <code>offset</code> attribute takes four possible
          values, allowing fine grained control over how the guest
          clock is synchronized to the host. NB, not all hypervisors
          support all modes.</p>
        <dl>
          <dt><code>utc</code></dt>
          <dd>
            The guest clock will always be synchronized to UTC when
2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200
            booted.
            <span class="since">Since 0.9.11</span> 'utc' mode can be converted
            to 'variable' mode, which can be controlled by using the
            <code>adjustment</code> attribute. If the value is 'reset', the
            conversion is never done (not all hypervisors can
            synchronize to UTC on each boot; use of 'reset' will cause
            an error on those hypervisors). A numeric value
            forces the conversion to 'variable' mode using the value as the
            initial adjustment. The default <code>adjustment</code> is
            hypervisor specific.
          </dd>
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          <dt><code>localtime</code></dt>
          <dd>
            The guest clock will be synchronized to the host's configured
            timezone when booted, if any.
2205 2206
            <span class="since">Since 0.9.11,</span> the <code>adjustment</code>
            attribute behaves the same as in 'utc' mode.
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          </dd>
          <dt><code>timezone</code></dt>
          <dd>
            The guest clock will be synchronized to the requested timezone
            using the <code>timezone</code> attribute.
            <span class="since">Since 0.7.7</span>
          </dd>
          <dt><code>variable</code></dt>
          <dd>
            The guest clock will have an arbitrary offset applied
2217 2218
            relative to UTC or localtime, depending on the <code>basis</code>
            attribute. The delta relative to UTC (or localtime) is specified
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            in seconds, using the <code>adjustment</code> attribute.
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            The guest is free to adjust the RTC over time and expect
2221 2222 2223
            that it will be honored at next reboot. This is in
            contrast to 'utc' and 'localtime' mode (with the optional
            attribute adjustment='reset'), where the RTC adjustments are
E
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            lost at each reboot. <span class="since">Since 0.7.7</span>
2225 2226
            <span class="since">Since 0.9.11</span> the <code>basis</code>
            attribute can be either 'utc' (default) or 'localtime'.
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          </dd>
        </dl>
        <p>
          A <code>clock</code> may have zero or more
2231
          <code>timer</code> sub-elements. <span class="since">Since
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          0.8.0</span>
        </p>
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      </dd>
2235 2236
      <dt><code>timer</code></dt>
      <dd>
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2237 2238 2239 2240 2241 2242 2243 2244 2245 2246
        <p>
          Each timer element requires a <code>name</code> attribute,
          and has other optional attributes that depend on
          the <code>name</code> specified.  Various hypervisors
          support different combinations of attributes.
        </p>
        <dl>
          <dt><code>name</code></dt>
          <dd>
            The <code>name</code> attribute selects which timer is
2247 2248 2249
            being modified, and can be one of
            "platform" (currently unsupported),
            "hpet" (libxl, xen, qemu), "kvmclock" (qemu),
2250 2251 2252 2253 2254 2255 2256
            "pit" (qemu), "rtc" (qemu), "tsc" (libxl) or "hypervclock"
            (qemu - <span class="since">since 1.2.2</span>).

            The <code>hypervclock</code> timer adds support for the
            reference time counter and the reference page for iTSC
            feature for guests running the Microsoft Windows
            operating system.
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          </dd>
          <dt><code>track</code></dt>
          <dd>
            The <code>track</code> attribute specifies what the timer
            tracks, and can be "boot", "guest", or "wall".
            Only valid for <code>name="rtc"</code>
            or <code>name="platform"</code>.
          </dd>
          <dt><code>tickpolicy</code></dt>
          <dd>
2267 2268
            <p>
            The <code>tickpolicy</code> attribute determines what
2269
            happens when QEMU misses a deadline for injecting a
2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292
            tick to the guest:
            </p>
            <dl>
              <dt><code>delay</code></dt>
              <dd>Continue to deliver ticks at the normal rate.
                The guest time will be delayed due to the late
                tick</dd>
              <dt><code>catchup</code></dt>
              <dd>Deliver ticks at a higher rate to catch up
                with the missed tick. The guest time should
                not be delayed once catchup is complete.</dd>
              <dt><code>merge</code></dt>
              <dd>Merge the missed tick(s) into one tick and
                inject. The guest time may be delayed, depending
                on how the OS reacts to the merging of ticks</dd>
              <dt><code>discard</code></dt>
              <dd>Throw away the missed tick(s) and continue
                with future injection normally. The guest time
                may be delayed, unless the OS has explicit
                handling of lost ticks</dd>
            </dl>
            <p>If the policy is "catchup", there can be further details in
            the <code>catchup</code> sub-element.</p>
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            <dl>
              <dt><code>catchup</code></dt>
              <dd>
                The <code>catchup</code> element has three optional
                attributes, each a positive integer.  The attributes
                are <code>threshold</code>, <code>slew</code>,
                and <code>limit</code>.
              </dd>
            </dl>
2302 2303 2304
            <p>
              Note that hypervisors are not required to support all policies across all time sources
            </p>
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          </dd>
          <dt><code>frequency</code></dt>
          <dd>
            The <code>frequency</code> attribute is an unsigned
            integer specifying the frequency at
            which <code>name="tsc"</code> runs.
          </dd>
          <dt><code>mode</code></dt>
          <dd>
            The <code>mode</code> attribute controls how
            the <code>name="tsc"</code> timer is managed, and can be
            "auto", "native", "emulate", "paravirt", or "smpsafe".
            Other timers are always emulated.
          </dd>
          <dt><code>present</code></dt>
          <dd>
            The <code>present</code> attribute can be "yes" or "no" to
            specify whether a particular timer is available to the guest.
          </dd>
        </dl>
2325
      </dd>
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    </dl>

2328
    <h3><a id="elementsPerf">Performance monitoring events</a></h3>
2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339

    <p>
      Some platforms allow monitoring of performance of the virtual machine and
      the code executed inside. To enable the performance monitoring events
      you can either specify them in the <code>perf</code> element or enable
      them via <code>virDomainSetPerfEvents</code> API. The performance values
      are then retrieved using the virConnectGetAllDomainStats API.
      <span class="since">Since 2.0.0</span>
    </p>

<pre>
2340 2341 2342 2343 2344 2345 2346 2347 2348
...
&lt;perf&gt;
  &lt;event name='cmt' enabled='yes'/&gt;
  &lt;event name='mbmt' enabled='no'/&gt;
  &lt;event name='mbml' enabled='yes'/&gt;
  &lt;event name='cpu_cycles' enabled='no'/&gt;
  &lt;event name='instructions' enabled='yes'/&gt;
  &lt;event name='cache_references' enabled='no'/&gt;
  &lt;event name='cache_misses' enabled='no'/&gt;
2349
  &lt;event name='branch_instructions' enabled='no'/&gt;
2350
  &lt;event name='branch_misses' enabled='no'/&gt;
2351
  &lt;event name='bus_cycles' enabled='no'/&gt;
2352
  &lt;event name='stalled_cycles_frontend' enabled='no'/&gt;
2353
  &lt;event name='stalled_cycles_backend' enabled='no'/&gt;
2354
  &lt;event name='ref_cpu_cycles' enabled='no'/&gt;
2355
  &lt;event name='cpu_clock' enabled='no'/&gt;
2356
  &lt;event name='task_clock' enabled='no'/&gt;
2357
  &lt;event name='page_faults' enabled='no'/&gt;
2358
  &lt;event name='context_switches' enabled='no'/&gt;
2359
  &lt;event name='cpu_migrations' enabled='no'/&gt;
2360
  &lt;event name='page_faults_min' enabled='no'/&gt;
2361
  &lt;event name='page_faults_maj' enabled='no'/&gt;
2362
  &lt;event name='alignment_faults' enabled='no'/&gt;
2363
  &lt;event name='emulation_faults' enabled='no'/&gt;
2364 2365
&lt;/perf&gt;
...
2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388
</pre>

  <table class="top_table">
    <tr>
      <th>event name</th>
      <th>Description</th>
      <th>stats parameter name</th>
    </tr>
    <tr>
      <td><code>cmt</code></td>
      <td>usage of l3 cache in bytes by applications running on the platform</td>
      <td><code>perf.cmt</code></td>
    </tr>
    <tr>
      <td><code>mbmt</code></td>
      <td>total system bandwidth from one level of cache</td>
      <td><code>perf.mbmt</code></td>
    </tr>
    <tr>
      <td><code>mbml</code></td>
      <td>bandwidth of memory traffic for a memory controller</td>
      <td><code>perf.mbml</code></td>
    </tr>
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    <tr>
      <td><code>cpu_cycles</code></td>
2391
      <td>the count of cpu cycles (total/elapsed)</td>
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      <td><code>perf.cpu_cycles</code></td>
    </tr>
    <tr>
      <td><code>instructions</code></td>
      <td>the count of instructions by applications running on the platform</td>
      <td><code>perf.instructions</code></td>
    </tr>
    <tr>
      <td><code>cache_references</code></td>
      <td>the count of cache hits by applications running on the platform</td>
      <td><code>perf.cache_references</code></td>
    </tr>
    <tr>
      <td><code>cache_misses</code></td>
      <td>the count of cache misses by applications running on the platform</td>
      <td><code>perf.cache_misses</code></td>
    </tr>
2409 2410 2411 2412 2413
    <tr>
      <td><code>branch_instructions</code></td>
      <td>the count of branch instructions by applications running on the platform</td>
      <td><code>perf.branch_instructions</code></td>
    </tr>
2414 2415 2416 2417 2418
    <tr>
      <td><code>branch_misses</code></td>
      <td>the count of branch misses by applications running on the platform</td>
      <td><code>perf.branch_misses</code></td>
    </tr>
2419 2420 2421 2422 2423
    <tr>
      <td><code>bus_cycles</code></td>
      <td>the count of bus cycles by applications running on the platform</td>
      <td><code>perf.bus_cycles</code></td>
    </tr>
2424 2425 2426 2427 2428 2429
    <tr>
      <td><code>stalled_cycles_frontend</code></td>
      <td>the count of stalled cpu cycles in the frontend of the instruction
          processor pipeline by applications running on the platform</td>
      <td><code>perf.stalled_cycles_frontend</code></td>
    </tr>
2430 2431 2432 2433 2434 2435
    <tr>
      <td><code>stalled_cycles_backend</code></td>
      <td>the count of stalled cpu cycles in the backend of the instruction
          processor pipeline by applications running on the platform</td>
      <td><code>perf.stalled_cycles_backend</code></td>
    </tr>
2436 2437 2438 2439 2440 2441
    <tr>
      <td><code>ref_cpu_cycles</code></td>
      <td>the count of total cpu cycles not affected by CPU frequency scaling
         by applications running on the platform</td>
      <td><code>perf.ref_cpu_cycles</code></td>
    </tr>
2442 2443 2444 2445 2446 2447 2448
    <tr>
      <td><code>cpu_clock</code></td>
      <td>the count of cpu clock time, as measured by a monotonic
          high-resolution per-CPU timer, by applications running on
          the platform</td>
      <td><code>perf.cpu_clock</code></td>
    </tr>
2449 2450 2451 2452 2453 2454 2455
    <tr>
      <td><code>task_clock</code></td>
      <td>the count of task clock time, as measured by a monotonic
          high-resolution CPU timer, specific to the task that
          is run by applications running on the platform</td>
      <td><code>perf.task_clock</code></td>
    </tr>
2456 2457 2458 2459 2460 2461 2462
    <tr>
      <td><code>page_faults</code></td>
      <td>the count of page faults by applications running on the
          platform. This includes minor, major, invalid and other
          types of page faults</td>
      <td><code>perf.page_faults</code></td>
    </tr>
2463 2464 2465 2466 2467 2468
    <tr>
      <td><code>context_switches</code></td>
      <td>the count of context switches by applications running on
          the platform</td>
      <td><code>perf.context_switches</code></td>
    </tr>
2469 2470 2471 2472 2473 2474 2475
    <tr>
      <td><code>cpu_migrations</code></td>
      <td>the count of cpu migrations, that is, where the process
          moved from one logical processor to another, by
          applications running on the platform</td>
      <td><code>perf.cpu_migrations</code></td>
    </tr>
2476 2477 2478 2479 2480 2481 2482 2483
    <tr>
      <td><code>page_faults_min</code></td>
      <td>the count of minor page faults, that is, where the
          page was present in the page cache, and therefore
          the fault avoided loading it from storage, by
          applications running on the platform</td>
      <td><code>perf.page_faults_min</code></td>
    </tr>
2484 2485 2486 2487 2488 2489 2490 2491
    <tr>
      <td><code>page_faults_maj</code></td>
      <td>the count of major page faults, that is, where the
          page was not present in the page cache, and
          therefore had to be fetched from storage, by
          applications running on the platform</td>
      <td><code>perf.page_faults_maj</code></td>
    </tr>
2492 2493 2494 2495 2496 2497 2498
    <tr>
      <td><code>alignment_faults</code></td>
      <td>the count of alignment faults, that is when
          the load or store is not aligned properly, by
          applications running on the platform</td>
      <td><code>perf.alignment_faults</code></td>
    </tr>
2499 2500 2501 2502 2503 2504 2505 2506
    <tr>
      <td><code>emulation_faults</code></td>
      <td>the count of emulation faults, that is when
          the kernel traps on unimplemented instrucions
          and emulates them for user space, by
          applications running on the platform</td>
      <td><code>perf.emulation_faults</code></td>
    </tr>
2507 2508
  </table>

2509
    <h3><a id="elementsDevices">Devices</a></h3>
D
Daniel P. Berrange 已提交
2510 2511

    <p>
A
Atsushi SAKAI 已提交
2512
      The final set of XML elements are all used to describe devices
D
Daniel P. Berrange 已提交
2513 2514 2515 2516 2517
      provided to the guest domain. All devices occur as children
      of the main <code>devices</code> element.
      <span class="since">Since 0.1.3</span>
    </p>

2518
<pre>
2519 2520 2521 2522 2523
...
&lt;devices&gt;
  &lt;emulator&gt;/usr/lib/xen/bin/qemu-dm&lt;/emulator&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
2524 2525 2526 2527

    <dl>
      <dt><code>emulator</code></dt>
      <dd>
M
Matthew Booth 已提交
2528 2529 2530 2531 2532
        The contents of the <code>emulator</code> element specify
        the fully qualified path to the device model emulator binary.
        The <a href="formatcaps.html">capabilities XML</a> specifies
        the recommended default emulator to use for each particular
        domain type / architecture combination.
D
Daniel P. Berrange 已提交
2533 2534 2535
      </dd>
    </dl>

M
Michal Privoznik 已提交
2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558
    <p>
      To help users identifying devices they care about, every
      device can have direct child <code>alias</code> element
      which then has <code>name</code> attribute where users can
      store identifier for the device. The identifier has to have
      "ua-" prefix and must be unique within the domain. Additionally, the
      identifier must consist only of the following characters:
      <code>[a-zA-Z0-9_-]</code>.
      <span class="since">Since 3.9.0</span>
    </p>

<pre>
&lt;devices&gt;
  &lt;disk type='file'&gt;
    &lt;alias name='ua-myDisk'/&gt;
  &lt;/disk&gt;
  &lt;interface type='network' trustGuestRxFilters='yes'&gt;
    &lt;alias name='ua-myNIC'/&gt;
  &lt;/interface&gt;
  ...
&lt;/devices&gt;
</pre>

2559
    <h4><a id="elementsDisks">Hard drives, floppy disks, CDROMs</a></h4>
D
Daniel P. Berrange 已提交
2560 2561 2562 2563 2564 2565 2566

    <p>
      Any device that looks like a disk, be it a floppy, harddisk,
      cdrom, or paravirtualized driver is specified via the <code>disk</code>
      element.
    </p>

2567
<pre>
2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582
...
&lt;devices&gt;
  &lt;disk type='file' snapshot='external'&gt;
    &lt;driver name="tap" type="aio" cache="default"/&gt;
    &lt;source file='/var/lib/xen/images/fv0' startupPolicy='optional'&gt;
      &lt;seclabel relabel='no'/&gt;
    &lt;/source&gt;
    &lt;target dev='hda' bus='ide'/&gt;
    &lt;iotune&gt;
      &lt;total_bytes_sec&gt;10000000&lt;/total_bytes_sec&gt;
      &lt;read_iops_sec&gt;400000&lt;/read_iops_sec&gt;
      &lt;write_iops_sec&gt;100000&lt;/write_iops_sec&gt;
    &lt;/iotune&gt;
    &lt;boot order='2'/&gt;
    &lt;encryption type='...'&gt;
M
MORITA Kazutaka 已提交
2583
      ...
2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606
    &lt;/encryption&gt;
    &lt;shareable/&gt;
    &lt;serial&gt;
      ...
    &lt;/serial&gt;
  &lt;/disk&gt;
    ...
  &lt;disk type='network'&gt;
    &lt;driver name="qemu" type="raw" io="threads" ioeventfd="on" event_idx="off"/&gt;
    &lt;source protocol="sheepdog" name="image_name"&gt;
      &lt;host name="hostname" port="7000"/&gt;
    &lt;/source&gt;
    &lt;target dev="hdb" bus="ide"/&gt;
    &lt;boot order='1'/&gt;
    &lt;transient/&gt;
    &lt;address type='drive' controller='0' bus='1' unit='0'/&gt;
  &lt;/disk&gt;
  &lt;disk type='network'&gt;
    &lt;driver name="qemu" type="raw"/&gt;
    &lt;source protocol="rbd" name="image_name2"&gt;
      &lt;host name="hostname" port="7000"/&gt;
      &lt;snapshot name="snapname"/&gt;
      &lt;config file="/path/to/file"/&gt;
2607 2608 2609
      &lt;auth username='myuser'&gt;
        &lt;secret type='ceph' usage='mypassid'/&gt;
      &lt;/auth&gt;
2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659
    &lt;/source&gt;
    &lt;target dev="hdc" bus="ide"/&gt;
  &lt;/disk&gt;
  &lt;disk type='block' device='cdrom'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;target dev='hdd' bus='ide' tray='open'/&gt;
    &lt;readonly/&gt;
  &lt;/disk&gt;
  &lt;disk type='network' device='cdrom'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source protocol="http" name="url_path"&gt;
      &lt;host name="hostname" port="80"/&gt;
    &lt;/source&gt;
    &lt;target dev='hde' bus='ide' tray='open'/&gt;
    &lt;readonly/&gt;
  &lt;/disk&gt;
  &lt;disk type='network' device='cdrom'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source protocol="https" name="url_path"&gt;
      &lt;host name="hostname" port="443"/&gt;
    &lt;/source&gt;
    &lt;target dev='hdf' bus='ide' tray='open'/&gt;
    &lt;readonly/&gt;
  &lt;/disk&gt;
  &lt;disk type='network' device='cdrom'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source protocol="ftp" name="url_path"&gt;
      &lt;host name="hostname" port="21"/&gt;
    &lt;/source&gt;
    &lt;target dev='hdg' bus='ide' tray='open'/&gt;
    &lt;readonly/&gt;
  &lt;/disk&gt;
  &lt;disk type='network' device='cdrom'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source protocol="ftps" name="url_path"&gt;
      &lt;host name="hostname" port="990"/&gt;
    &lt;/source&gt;
    &lt;target dev='hdh' bus='ide' tray='open'/&gt;
    &lt;readonly/&gt;
  &lt;/disk&gt;
  &lt;disk type='network' device='cdrom'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source protocol="tftp" name="url_path"&gt;
      &lt;host name="hostname" port="69"/&gt;
    &lt;/source&gt;
    &lt;target dev='hdi' bus='ide' tray='open'/&gt;
    &lt;readonly/&gt;
  &lt;/disk&gt;
  &lt;disk type='block' device='lun'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
2660
    &lt;source dev='/dev/sda'&gt;
2661
      &lt;reservations managed='no'&gt;
2662 2663
        &lt;source type='unix' path='/path/to/qemu-pr-helper' mode='client'/&gt;
      &lt;/reservations&gt;
2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682
    &lt;target dev='sda' bus='scsi'/&gt;
    &lt;address type='drive' controller='0' bus='0' target='3' unit='0'/&gt;
  &lt;/disk&gt;
  &lt;disk type='block' device='disk'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source dev='/dev/sda'/&gt;
    &lt;geometry cyls='16383' heads='16' secs='63' trans='lba'/&gt;
    &lt;blockio logical_block_size='512' physical_block_size='4096'/&gt;
    &lt;target dev='hdj' bus='ide'/&gt;
  &lt;/disk&gt;
  &lt;disk type='volume' device='disk'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source pool='blk-pool0' volume='blk-pool0-vol0'/&gt;
    &lt;target dev='hdk' bus='ide'/&gt;
  &lt;/disk&gt;
  &lt;disk type='network' device='disk'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source protocol='iscsi' name='iqn.2013-07.com.example:iscsi-nopool/2'&gt;
      &lt;host name='example.com' port='3260'/&gt;
2683 2684 2685
      &lt;auth username='myuser'&gt;
        &lt;secret type='iscsi' usage='libvirtiscsi'/&gt;
      &lt;/auth&gt;
2686 2687 2688 2689 2690 2691 2692
    &lt;/source&gt;
    &lt;target dev='vda' bus='virtio'/&gt;
  &lt;/disk&gt;
  &lt;disk type='network' device='lun'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source protocol='iscsi' name='iqn.2013-07.com.example:iscsi-nopool/1'&gt;
      &lt;host name='example.com' port='3260'/&gt;
2693 2694 2695
      &lt;auth username='myuser'&gt;
        &lt;secret type='iscsi' usage='libvirtiscsi'/&gt;
      &lt;/auth&gt;
2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709
    &lt;/source&gt;
    &lt;target dev='sdb' bus='scsi'/&gt;
  &lt;/disk&gt;
  &lt;disk type='volume' device='disk'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source pool='iscsi-pool' volume='unit:0:0:1' mode='host'/&gt;
    &lt;target dev='vdb' bus='virtio'/&gt;
  &lt;/disk&gt;
  &lt;disk type='volume' device='disk'&gt;
    &lt;driver name='qemu' type='raw'/&gt;
    &lt;source pool='iscsi-pool' volume='unit:0:0:2' mode='direct'/&gt;
    &lt;target dev='vdc' bus='virtio'/&gt;
  &lt;/disk&gt;
  &lt;disk type='file' device='disk'&gt;
L
Lin Ma 已提交
2710
    &lt;driver name='qemu' type='qcow2' queues='4'/&gt;
2711 2712 2713 2714 2715 2716 2717 2718
    &lt;source file='/var/lib/libvirt/images/domain.qcow'/&gt;
    &lt;backingStore type='file'&gt;
      &lt;format type='qcow2'/&gt;
      &lt;source file='/var/lib/libvirt/images/snapshot.qcow'/&gt;
      &lt;backingStore type='block'&gt;
        &lt;format type='raw'/&gt;
        &lt;source dev='/dev/mapper/base'/&gt;
        &lt;backingStore/&gt;
2719
      &lt;/backingStore&gt;
2720 2721 2722 2723 2724
    &lt;/backingStore&gt;
    &lt;target dev='vdd' bus='virtio'/&gt;
  &lt;/disk&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
2725 2726 2727

    <dl>
      <dt><code>disk</code></dt>
2728 2729
      <dd>The <code>disk</code> element is the main container for
      describing disks and supports the following attributes:
2730
        <dl>
2731
          <dt><code>type</code></dt>
2732 2733 2734 2735 2736 2737
            <dd>
            Valid values are "file", "block",
            "dir" (<span class="since">since 0.7.5</span>),
            "network" (<span class="since">since 0.8.7</span>), or
            "volume" (<span class="since">since 1.0.5</span>)
            and refer to the underlying source for the disk.
2738
            <span class="since">Since 0.0.3</span>
2739
            </dd>
2740
          <dt><code>device</code></dt>
2741 2742 2743 2744 2745 2746
            <dd>
            Indicates how the disk is to be exposed to the guest OS. Possible
            values for this attribute are "floppy", "disk", "cdrom", and "lun",
            defaulting to "disk".
            <p>
            Using "lun" (<span class="since">since 0.9.10</span>) is only
2747 2748
            valid when the <code>type</code> is "block" or "network" for
            <code>protocol='iscsi'</code> or when the <code>type</code>
2749
            is "volume" when using an iSCSI source <code>pool</code>
2750 2751 2752
            for <code>mode</code> "host" or as an
            <a href="http://wiki.libvirt.org/page/NPIV_in_libvirt">NPIV</a>
            virtual Host Bus Adapter (vHBA) using a Fibre Channel storage pool.
2753
            Configured in this manner, the LUN behaves identically to "disk",
2754 2755 2756 2757 2758 2759
            except that generic SCSI commands from the guest are accepted
            and passed through to the physical device. Also note that
            device='lun' will only be recognized for actual raw devices,
            but never for individual partitions or LVM partitions (in those
            cases, the kernel will reject the generic SCSI commands, making
            it identical to device='disk').
2760
            <span class="since">Since 0.1.4</span>
2761 2762
            </p>
            </dd>
2763
          <dt><code>rawio</code></dt>
2764
            <dd>
2765
            Indicates whether the disk needs rawio capability. Valid
2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776
            settings are "yes" or "no" (default is "no"). If any one disk
            in a domain has rawio='yes', rawio capability will be enabled
            for all disks in the domain (because, in the case of QEMU, this
            capability can only be set on a per-process basis). This attribute
            is only valid when device is "lun". NB, <code>rawio</code> intends
            to confine the capability per-device, however, current QEMU
            implementation gives the domain process broader capability
            than that (per-process basis, affects all the domain disks).
            To confine the capability as much as possible for QEMU driver
            as this stage, <code>sgio</code> is recommended, it's more
            secure than <code>rawio</code>.
2777
            <span class="since">Since 0.9.10</span>
2778
            </dd>
2779
          <dt><code>sgio</code></dt>
2780
            <dd>
2781 2782 2783 2784
            If supported by the hypervisor and OS, indicates whether
            unprivileged SG_IO commands are filtered for the disk. Valid
            settings are "filtered" or "unfiltered" where the default is
            "filtered". Only available when the <code>device</code> is 'lun'.
2785
            <span class="since">Since 1.0.2</span>
2786
            </dd>
2787
          <dt><code>snapshot</code></dt>
2788 2789
            <dd>
            Indicates the default behavior of the disk during disk snapshots:
2790 2791 2792 2793 2794 2795 2796
            "<code>internal</code>" requires a file format such as qcow2 that
            can store both the snapshot and the data changes since the snapshot;
            "<code>external</code>" will separate the snapshot from the live
            data; and "<code>no</code>" means the disk will not participate in
            snapshots. Read-only disks default to "<code>no</code>", while the
            default for other disks depends on the hypervisor's capabilities.
            Some hypervisors allow a per-snapshot choice as well, during
2797
            <a href="formatsnapshot.html">domain snapshot creation</a>.
2798 2799
            Not all snapshot modes are supported; for example, enabling
            snapshots with a transient disk generally does not make sense.
2800
            <span class="since">Since 0.9.5</span>
2801 2802 2803
            </dd>
        </dl>
      </dd>
D
Daniel P. Berrange 已提交
2804
      <dt><code>source</code></dt>
2805 2806 2807
      <dd>Representation of the disk <code>source</code> depends on the
      disk <code>type</code> attribute value as follows:
          <dl>
2808
            <dt><code>file</code></dt>
2809 2810 2811
              <dd>
              The <code>file</code> attribute specifies the fully-qualified
              path to the file holding the disk.
2812
              <span class="since">Since 0.0.3</span>
2813
              </dd>
2814
            <dt><code>block</code></dt>
2815
              <dd>
2816 2817
              The <code>dev</code> attribute specifies the fully-qualified path
              to the host device to serve as the disk.
2818
              <span class="since">Since 0.0.3</span>
2819
              </dd>
2820
            <dt><code>dir</code></dt>
2821 2822 2823
              <dd>
              The <code>dir</code> attribute specifies the fully-qualified path
              to the directory to use as the disk.
2824
              <span class="since">Since 0.7.5</span>
2825
              </dd>
2826
            <dt><code>network</code></dt>
2827 2828 2829
              <dd>
              The <code>protocol</code> attribute specifies the protocol to
              access to the requested image. Possible values are "nbd",
2830 2831 2832 2833 2834 2835 2836
              "iscsi", "rbd", "sheepdog", "gluster" or "vxhs".

              <p>If the <code>protocol</code> attribute is "rbd", "sheepdog",
              "gluster", or "vxhs", an additional attribute <code>name</code>
              is mandatory to specify which volume/image will be used.
              </p>

2837 2838 2839 2840 2841 2842 2843
              <p>For "nbd", the <code>name</code> attribute is optional. TLS
              transport for NBD can be enabled by setting the <code>tls</code>
              attribute to <code>yes</code>. For the QEMU hypervisor, usage of
              a TLS environment can also be globally controlled on the host by
              the <code>nbd_tls</code> and <code>nbd_tls_x509_cert_dir</code> in
              /etc/libvirt/qemu.conf.
              ('tls' <span class="since">Since 4.5.0</span>)
2844 2845 2846 2847 2848
              </p>

              <p>For "iscsi" (<span class="since">since 1.0.4</span>), the
              <code>name</code> attribute may include a logical unit number,
              separated from the target's name by a slash (e.g.,
2849 2850
              <code>iqn.2013-07.com.example:iscsi-pool/1</code>). If not
              specified, the default LUN is zero.
2851 2852
              </p>

2853
              <p>For "vxhs" (<span class="since">since 3.8.0</span>), the
2854
              <code>name</code> is the UUID of the volume, assigned by the
2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867
              HyperScale server. Additionally, an optional attribute
              <code>tls</code> (QEMU only) can be used to control whether a
              VxHS block device would utilize a hypervisor configured TLS
              X.509 certificate environment in order to encrypt the data
              channel. For the QEMU hypervisor, usage of a TLS environment can
              also be globally controlled on the host by the
              <code>vxhs_tls</code> and <code>vxhs_tls_x509_cert_dir</code> or
              <code>default_tls_x509_cert_dir</code> settings in the file
              /etc/libvirt/qemu.conf. If <code>vxhs_tls</code> is enabled,
              then unless the domain <code>tls</code> attribute is set to "no",
              libvirt will use the host configured TLS environment. If the
              <code>tls</code> attribute is set to "yes", then regardless of
              the qemu.conf setting, TLS authentication will be attempted.
2868
              </p>
2869
              <span class="since">Since 0.8.7</span>
2870
              </dd>
2871
            <dt><code>volume</code></dt>
2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897
              <dd>
              The underlying disk source is represented by attributes
              <code>pool</code> and <code>volume</code>. Attribute
              <code>pool</code> specifies the name of the
              <a href="formatstorage.html">storage pool</a> (managed
              by libvirt) where the disk source resides. Attribute
              <code>volume</code> specifies the name of storage volume (managed
              by libvirt) used as the disk source. The value for the
              <code>volume</code> attribute will be the output from the "Name"
              column of a <code>virsh vol-list [pool-name]</code> command.
              <p>
              Use the attribute <code>mode</code>
              (<span class="since">since 1.1.1</span>) to indicate how to
              represent the LUN as the disk source. Valid values are
              "direct" and "host". If <code>mode</code> is not specified,
              the default is to use "host".

              Using "direct" as the <code>mode</code> value indicates to use
              the <a href="formatstorage.html">storage pool's</a>
              <code>source</code> element <code>host</code> attribute as
              the disk source to generate the libiscsi URI (e.g.
              'file=iscsi://example.com:3260/iqn.2013-07.com.example:iscsi-pool/1').

              Using "host" as the <code>mode</code> value indicates to use the
              LUN's path as it shows up on host (e.g.
              'file=/dev/disk/by-path/ip-example.com:3260-iscsi-iqn.2013-07.com.example:iscsi-pool-lun-1').
2898 2899 2900

              Using a LUN from an iSCSI source pool provides the same
              features as a <code>disk</code> configured using
2901
              <code>type</code> 'block' or 'network' and <code>device</code>
2902
              of 'lun' with respect to how the LUN is presented to and
2903
              may be used by the guest.
2904

2905
              <span class="since">Since 1.0.5</span>
2906 2907 2908 2909
              </p>
              </dd>
          </dl>
        With "file", "block", and "volume", one or more optional
2910
        sub-elements <code>seclabel</code>, <a href="#seclabel">described
2911 2912
        below</a> (and <span class="since">since 0.9.9</span>), can be
        used to override the domain security labeling policy for just
2913 2914
        that source file. (NB, for "volume" type disk, <code>seclabel</code>
        is only valid when the specified storage volume is of 'file' or
2915 2916
        'block' type).
        <p>
2917
        The <code>source</code> element may contain the following sub elements:
2918
        </p>
2919 2920 2921 2922 2923

        <dl>
          <dt><code>host</code></dt>
          <dd>
            <p>
2924 2925 2926 2927
            When the disk <code>type</code> is "network", the <code>source</code>
            may have zero or more <code>host</code> sub-elements used to
            specify the hosts to connect.

2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956
            The <code>host</code> element supports 4 attributes, viz.  "name",
            "port", "transport" and "socket", which specify the hostname,
            the port number, transport type and path to socket, respectively.
            The meaning of this element and the number of the elements depend
            on the protocol attribute.
            </p>
            <table class="top_table">
              <tr>
                <th> Protocol </th>
                <th> Meaning </th>
                <th> Number of hosts </th>
                <th> Default port </th>
              </tr>
              <tr>
                <td> nbd </td>
                <td> a server running nbd-server </td>
                <td> only one </td>
                <td> 10809 </td>
              </tr>
              <tr>
                <td> iscsi </td>
                <td> an iSCSI server </td>
                <td> only one </td>
                <td> 3260 </td>
              </tr>
              <tr>
                <td> rbd </td>
                <td> monitor servers of RBD </td>
                <td> one or more </td>
2957
                <td> librados default </td>
2958 2959 2960 2961 2962 2963 2964 2965 2966 2967
              </tr>
              <tr>
                <td> sheepdog </td>
                <td> one of the sheepdog servers (default is localhost:7000) </td>
                <td> zero or one </td>
                <td> 7000 </td>
              </tr>
              <tr>
                <td> gluster </td>
                <td> a server running glusterd daemon </td>
2968
                <td> one or more (<span class="since">Since 2.1.0</span>), just one prior to that </td>
2969 2970
                <td> 24007 </td>
              </tr>
2971 2972 2973 2974 2975 2976
              <tr>
                <td> vxhs </td>
                <td> a server running Veritas HyperScale daemon </td>
                <td> only one </td>
                <td> 9999 </td>
              </tr>
2977 2978 2979 2980 2981 2982 2983 2984 2985
            </table>
            <p>
            gluster supports "tcp", "rdma", "unix" as valid values for the
            transport attribute.  nbd supports "tcp" and "unix".  Others only
            support "tcp".  If nothing is specified, "tcp" is assumed. If the
            transport is "unix", the socket attribute specifies the path to an
            AF_UNIX socket.
            </p>
          </dd>
2986 2987 2988 2989 2990 2991 2992
          <dt><code>snapshot</code></dt>
          <dd>
            The <code>name</code> attribute of <code>snapshot</code> element can
            optionally specify an internal snapshot name to be used as the
            source for storage protocols.
            Supported for 'rbd' <span class="since">since 1.2.11 (QEMU only).</span>
          </dd>
2993 2994 2995 2996 2997 2998 2999 3000
          <dt><code>config</code></dt>
          <dd>
            The <code>file</code> attribute for the <code>config</code> element
            provides a fully qualified path to a configuration file to be
            provided as a parameter to the client of a networked storage
            protocol. Supported for 'rbd' <span class="since">since 1.2.11
            (QEMU only).</span>
          </dd>
3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022
          <dt><code>auth</code></dt>
          <dd><span class="since">Since libvirt 3.9.0</span>, the
            <code>auth</code> element is supported for a disk
            <code>type</code> "network" that is using a <code>source</code>
            element with the <code>protocol</code> attributes "rbd" or "iscsi".
            If present, the <code>auth</code> element provides the
            authentication credentials needed to access the source.  It
            includes a mandatory attribute <code>username</code>, which
            identifies the username to use during authentication, as well
            as a sub-element <code>secret</code> with mandatory
            attribute <code>type</code>, to tie back to
            a <a href="formatsecret.html">libvirt secret object</a> that
            holds the actual password or other credentials (the domain XML
            intentionally does not expose the password, only the reference
            to the object that does manage the password).
            Known secret types are "ceph" for Ceph RBD network sources and
            "iscsi" for CHAP authentication of iSCSI targets.
            Both will require either a <code>uuid</code> attribute
            with the UUID of the secret object or a <code>usage</code>
            attribute matching the key that was specified in the
            secret object.
          </dd>
3023
          <dt><code>encryption</code></dt>
3024 3025 3026 3027 3028 3029 3030
          <dd><span class="since">Since libvirt 3.9.0</span>, the
            <code>encryption</code> can be a sub-element of the
            <code>source</code> element for encrypted storage sources.
            If present, specifies how the storage source is encrypted
            See the
            <a href="formatstorageencryption.html">Storage Encryption</a>
            page for more information.
3031 3032 3033 3034
            <p/>
            Note that the 'qcow' format of encryption is broken and thus is no
            longer supported for use with disk images.
            (<span class="since">Since libvirt 4.5.0</span>)
3035
          </dd>
3036 3037 3038 3039
          <dt><code>reservations</code></dt>
          <dd><span class="since">Since libvirt 4.4.0</span>, the
            <code>reservations</code> can be a sub-element of the
            <code>source</code> element for storage sources (QEMU driver only).
3040
            If present it enables persistent reservations for SCSI
3041
            based disks. The element has one mandatory attribute
3042 3043 3044 3045 3046 3047 3048 3049 3050
            <code>managed</code> with accepted values <code>yes</code> and
            <code>no</code>. If <code>managed</code> is enabled libvirt prepares
            and manages any resources needed. When the persistent reservations
            are unmanaged, then the hypervisor acts as a client and the path to
            the server socket must be provided in the child element
            <code>source</code>, which currently accepts only the following
            attributes:
            <code>type</code> with one value <code>unix</code>,
            <code>path</code> path to the socket, and
3051
            finally <code>mode</code> which accepts one value
3052
            <code>client</code> specifying the role of hypervisor.
3053 3054 3055
            It's recommended to allow libvirt manage the persistent
            reservations.
          </dd>
3056 3057
        </dl>

3058
        <p>
3059
        For a "file" or "volume" disk type which represents a cdrom or floppy
3060 3061
        (the <code>device</code> attribute), it is possible to define
        policy what to do with the disk if the source file is not accessible.
3062 3063
        (NB, <code>startupPolicy</code> is not valid for "volume" disk unless
         the specified storage volume is of "file" type). This is done by the
3064 3065
        <code>startupPolicy</code> attribute
        (<span class="since">since 0.9.7</span>),
3066
        accepting these values:
3067
        </p>
3068 3069 3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082
        <table class="top_table">
          <tr>
            <td> mandatory </td>
            <td> fail if missing for any reason (the default) </td>
          </tr>
          <tr>
            <td> requisite </td>
            <td> fail if missing on boot up,
                 drop if missing on migrate/restore/revert </td>
          </tr>
          <tr>
            <td> optional </td>
            <td> drop if missing at any start attempt </td>
          </tr>
        </table>
3083 3084 3085 3086 3087 3088 3089
        <p>
        <span class="since">Since 1.1.2</span> the <code>startupPolicy</code>
        is extended to support hard disks besides cdrom and floppy. On guest
        cold bootup, if a certain disk is not accessible or its disk chain is
        broken, with startupPolicy 'optional' the guest will drop this disk.
        This feature doesn't support migration currently.
        </p>
3090
        </dd>
3091 3092
      <dt><code>backingStore</code></dt>
      <dd>
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Deepak Shetty 已提交
3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106
        This element describes the backing store used by the disk
        specified by sibling <code>source</code> element. It is
        currently ignored on input and only used for output to
        describe the detected backing chains of running
        domains <span class="since">since 1.2.4</span> (although a
        future version of libvirt may start accepting chains on input,
        or output information for offline domains). An
        empty <code>backingStore</code> element means the sibling
        source is self-contained and is not based on any backing
        store. For backing chain information to be accurate, the
        backing format must be correctly specified in the metadata of
        each file of the chain (files created by libvirt satisfy this
        property, but using existing external files for snapshot or
        block copy operations requires the end user to pre-create the
3107
        file correctly). The following attributes are
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Deepak Shetty 已提交
3108
        supported in <code>backingStore</code>:
3109
        <dl>
3110
          <dt><code>type</code></dt>
3111 3112 3113 3114 3115
          <dd>
            The <code>type</code> attribute represents the type of disk used
            by the backing store, see disk type attribute above for more
            details and possible values.
          </dd>
3116
          <dt><code>index</code></dt>
3117 3118 3119 3120 3121 3122 3123 3124
          <dd>
            This attribute is only valid in output (and ignored on input) and
            it can be used to refer to a specific part of the disk chain when
            doing block operations (such as via the
            <code>virDomainBlockRebase</code> API). For example,
            <code>vda[2]</code> refers to the backing store with
            <code>index='2'</code> of the disk with <code>vda</code> target.
          </dd>
3125 3126 3127 3128
        </dl>
        Moreover, <code>backingStore</code> supports the following sub-elements:
        <dl>
          <dt><code>format</code></dt>
3129 3130 3131 3132 3133
          <dd>
            The <code>format</code> element contains <code>type</code>
            attribute which specifies the internal format of the backing
            store, such as <code>raw</code> or <code>qcow2</code>.
          </dd>
3134
          <dt><code>source</code></dt>
3135 3136 3137 3138 3139 3140
          <dd>
            This element has the same structure as the <code>source</code>
            element in <code>disk</code>. It specifies which file, device,
            or network location contains the data of the described backing
            store.
          </dd>
3141
          <dt><code>backingStore</code></dt>
3142 3143 3144 3145 3146 3147 3148
          <dd>
            If the backing store is not self-contained, the next element
            in the chain is described by nested <code>backingStore</code>
            element.
          </dd>
        </dl>
      </dd>
3149 3150
      <dt><code>mirror</code></dt>
      <dd>
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3151 3152 3153 3154
        This element is present if the hypervisor has started a
        long-running block job operation, where the mirror location in
        the <code>source</code> sub-element will eventually have the
        same contents as the source, and with the file format in the
E
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3155 3156 3157 3158
        sub-element <code>format</code> (which might differ from the
        format of the source).  The details of the <code>source</code>
        sub-element are determined by the <code>type</code> attribute
        of the mirror, similar to what is done for the
E
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3159 3160 3161 3162 3163
        overall <code>disk</code> device element. The <code>job</code>
        attribute mentions which API started the operation ("copy" for
        the <code>virDomainBlockRebase</code> API, or "active-commit"
        for the <code>virDomainBlockCommit</code>
        API), <span class="since">since 1.2.7</span>.  The
3164 3165 3166 3167 3168 3169
        attribute <code>ready</code>, if present, tracks progress of
        the job: <code>yes</code> if the disk is known to be ready to
        pivot, or, <span class="since">since
        1.2.7</span>, <code>abort</code> or <code>pivot</code> if the
        job is in the process of completing.  If <code>ready</code> is
        not present, the disk is probably still
3170
        copying.  For now, this element only valid in output; it is
3171 3172 3173 3174 3175 3176 3177
        ignored on input.  The <code>source</code> sub-element exists
        for all two-phase jobs <span class="since">since 1.2.6</span>.
        Older libvirt supported only block copy to a
        file, <span class="since">since 0.9.12</span>; for
        compatibility with older clients, such jobs include redundant
        information in the attributes <code>file</code>
        and <code>format</code> in the <code>mirror</code> element.
3178
      </dd>
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      <dt><code>target</code></dt>
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3180 3181 3182 3183 3184 3185 3186 3187
      <dd>The <code>target</code> element controls the bus / device
        under which the disk is exposed to the guest
        OS. The <code>dev</code> attribute indicates the "logical"
        device name. The actual device name specified is not
        guaranteed to map to the device name in the guest OS. Treat it
        as a device ordering hint.  The optional <code>bus</code>
        attribute specifies the type of disk device to emulate;
        possible values are driver specific, with typical values being
3188 3189
        "ide", "scsi", "virtio", "xen", "usb", "sata", or
        "sd" <span class="since">"sd" since 1.1.2</span>. If omitted, the bus
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3190 3191
        type is inferred from the style of the device name (e.g. a device named
        'sda' will typically be exported using a SCSI bus). The optional
3192 3193 3194 3195
        attribute <code>tray</code> indicates the tray status of the
        removable disks (i.e. CDROM or Floppy disk), the value can be either
        "open" or "closed", defaults to "closed". NB, the value of
        <code>tray</code> could be updated while the domain is running.
3196 3197 3198 3199
        The optional attribute <code>removable</code> sets the
        removable flag for USB disks, and its value can be either "on"
        or "off", defaulting to "off". <span class="since">Since
        0.0.3; <code>bus</code> attribute since 0.4.3;
3200
        <code>tray</code> attribute since 0.9.11; "usb" attribute value since
3201 3202
        after 0.4.4; "sata" attribute value since 0.9.7; "removable" attribute
        value since 1.1.3</span>
3203
      </dd>
L
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3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236
      <dt><code>iotune</code></dt>
      <dd>The optional <code>iotune</code> element provides the
        ability to provide additional per-device I/O tuning, with
        values that can vary for each device (contrast this to
        the <a href="#elementsBlockTuning"><code>&lt;blkiotune&gt;</code></a>
        element, which applies globally to the domain).  Currently,
        the only tuning available is Block I/O throttling for qemu.
        This element has optional sub-elements; any sub-element not
        specified or given with a value of 0 implies no
        limit.  <span class="since">Since 0.9.8</span>
        <dl>
          <dt><code>total_bytes_sec</code></dt>
          <dd>The optional <code>total_bytes_sec</code> element is the
            total throughput limit in bytes per second.  This cannot
            appear with <code>read_bytes_sec</code>
            or <code>write_bytes_sec</code>.</dd>
          <dt><code>read_bytes_sec</code></dt>
          <dd>The optional <code>read_bytes_sec</code> element is the
            read throughput limit in bytes per second.</dd>
          <dt><code>write_bytes_sec</code></dt>
          <dd>The optional <code>write_bytes_sec</code> element is the
            write throughput limit in bytes per second.</dd>
          <dt><code>total_iops_sec</code></dt>
          <dd>The optional <code>total_iops_sec</code> element is the
            total I/O operations per second.  This cannot
            appear with <code>read_iops_sec</code>
            or <code>write_iops_sec</code>.</dd>
          <dt><code>read_iops_sec</code></dt>
          <dd>The optional <code>read_iops_sec</code> element is the
            read I/O operations per second.</dd>
          <dt><code>write_iops_sec</code></dt>
          <dd>The optional <code>write_iops_sec</code> element is the
            write I/O operations per second.</dd>
3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260
          <dt><code>total_bytes_sec_max</code></dt>
          <dd>The optional <code>total_bytes_sec_max</code> element is the
            maximum total throughput limit in bytes per second.  This cannot
            appear with <code>read_bytes_sec_max</code>
            or <code>write_bytes_sec_max</code>.</dd>
          <dt><code>read_bytes_sec_max</code></dt>
          <dd>The optional <code>read_bytes_sec_max</code> element is the
            maximum read throughput limit in bytes per second.</dd>
          <dt><code>write_bytes_sec_max</code></dt>
          <dd>The optional <code>write_bytes_sec_max</code> element is the
            maximum write throughput limit in bytes per second.</dd>
          <dt><code>total_iops_sec_max</code></dt>
          <dd>The optional <code>total_iops_sec_max</code> element is the
            maximum total I/O operations per second.  This cannot
            appear with <code>read_iops_sec_max</code>
            or <code>write_iops_sec_max</code>.</dd>
          <dt><code>read_iops_sec_max</code></dt>
          <dd>The optional <code>read_iops_sec_max</code> element is the
            maximum read I/O operations per second.</dd>
          <dt><code>write_iops_sec_max</code></dt>
          <dd>The optional <code>write_iops_sec_max</code> element is the
            maximum write I/O operations per second.</dd>
          <dt><code>size_iops_sec</code></dt>
          <dd>The optional <code>size_iops_sec</code> element is the
3261 3262 3263 3264 3265
            size of I/O operations per second.
          <p>
            <span class="since">Throughput limits since 1.2.11 and QEMU 1.7</span>
          </p>
          </dd>
3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276
          <dt><code>group_name</code></dt>
          <dd>The optional <code>group_name</code> provides the cability
            to share I/O throttling quota between multiple drives. This
            prevents end-users from circumventing a hosting provider's
            throttling policy by splitting 1 large drive in N small drives
            and getting N times the normal throttling quota. Any name may
            be used.
          <p>
            <span class="since">group_name since 3.0.0 and QEMU 2.4</span>
          </p>
          </dd>
3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310
          <dt><code>total_bytes_sec_max_length</code></dt>
          <dd>The optional <code>total_bytes_sec_max_length</code>
            element is the maximum duration in seconds for the
            <code>total_bytes_sec_max</code> burst period. Only valid
            when the <code>total_bytes_sec_max</code> is set.</dd>
          <dt><code>read_bytes_sec_max_length</code></dt>
          <dd>The optional <code>read_bytes_sec_max_length</code>
            element is the maximum duration in seconds for the
            <code>read_bytes_sec_max</code> burst period. Only valid
            when the <code>read_bytes_sec_max</code> is set.</dd>
          <dt><code>write_bytes_sec_max</code></dt>
          <dd>The optional <code>write_bytes_sec_max_length</code>
            element is the maximum duration in seconds for the
            <code>write_bytes_sec_max</code> burst period. Only valid
            when the <code>write_bytes_sec_max</code> is set.</dd>
          <dt><code>total_iops_sec_max_length</code></dt>
          <dd>The optional <code>total_iops_sec_max_length</code>
            element is the maximum duration in seconds for the
            <code>total_iops_sec_max</code> burst period. Only valid
            when the <code>total_iops_sec_max</code> is set.</dd>
          <dt><code>read_iops_sec_max_length</code></dt>
          <dd>The optional <code>read_iops_sec_max_length</code>
            element is the maximum duration in seconds for the
            <code>read_iops_sec_max</code> burst period. Only valid
            when the <code>read_iops_sec_max</code> is set.</dd>
          <dt><code>write_iops_sec_max</code></dt>
          <dd>The optional <code>write_iops_sec_max_length</code>
            element is the maximum duration in seconds for the
            <code>write_iops_sec_max</code> burst period. Only valid
            when the <code>write_iops_sec_max</code> is set.
          <p>
            <span class="since">Throughput length since 2.4.0 and QEMU 2.6</span>
          </p>
          </dd>
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3311
        </dl>
3312
      </dd>
D
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3313
      <dt><code>driver</code></dt>
M
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3314 3315 3316
      <dd>
        The optional driver element allows specifying further details
        related to the hypervisor driver used to provide the disk.
3317
        <span class="since">Since 0.1.8</span>
M
Matthias Dahl 已提交
3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331
        <ul>
          <li>
            If the hypervisor supports multiple backend drivers, then
            the <code>name</code> attribute selects the primary
            backend driver name, while the optional <code>type</code>
            attribute provides the sub-type.  For example, xen
            supports a name of "tap", "tap2", "phy", or "file", with a
            type of "aio", while qemu only supports a name of "qemu",
            but multiple types including "raw", "bochs", "qcow2", and
            "qed".
          </li>
          <li>
            The optional <code>cache</code> attribute controls the
            cache mechanism, possible values are "default", "none",
3332 3333 3334 3335 3336 3337 3338 3339 3340
            "writethrough", "writeback", "directsync" (like
            "writethrough", but it bypasses the host page cache) and
            "unsafe" (host may cache all disk io, and sync requests from
            guest are ignored).
            <span class="since">
              Since 0.6.0,
              "directsync" since 0.9.5,
              "unsafe" since 0.9.7
            </span>
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          </li>
          <li>
            The optional <code>error_policy</code> attribute controls
3344 3345 3346
            how the hypervisor will behave on a disk read or write
            error, possible values are "stop", "report", "ignore", and
            "enospace".<span class="since">Since 0.8.0, "report" since
3347 3348
            0.9.7</span> The default is left to the discretion of the
            hypervisor. There is also an
3349 3350
            optional <code>rerror_policy</code> that controls behavior
            for read errors only. <span class="since">Since
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3351
            0.9.7</span>. If no rerror_policy is given, error_policy
3352 3353 3354 3355 3356
            is used for both read and write errors. If rerror_policy
            is given, it overrides the <code>error_policy</code> for
            read errors. Also note that "enospace" is not a valid
            policy for read errors, so if <code>error_policy</code> is
            set to "enospace" and no <code>rerror_policy</code> is
3357
            given, the read error policy will be left at its default.
M
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3358 3359 3360 3361
          </li>
          <li>
            The optional <code>io</code> attribute controls specific
            policies on I/O; qemu guests support "threads" and
3362
            "native". <span class="since">Since 0.8.8</span>
M
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3363
          </li>
3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377
          <li>
            The optional <code>ioeventfd</code> attribute allows users to
            set <a href='https://patchwork.kernel.org/patch/43390/'>
            domain I/O asynchronous handling</a> for disk device.
            The default is left to the discretion of the hypervisor.
            Accepted values are "on" and "off". Enabling this allows
            qemu to execute VM while a separate thread handles I/O.
            Typically guests experiencing high system CPU utilization
            during I/O will benefit from this. On the other hand,
            on overloaded host it could increase guest I/O latency.
            <span class="since">Since 0.9.3 (QEMU and KVM only)</span>
            <b>In general you should leave this option alone, unless you
            are very certain you know what you are doing.</b>
          </li>
3378 3379 3380 3381
          <li>
            The optional <code>event_idx</code> attribute controls
            some aspects of device event processing. The value can be
            either 'on' or 'off' - if it is on, it will reduce the
3382
            number of interrupts and exits for the guest. The default
3383 3384 3385 3386 3387 3388 3389 3390
            is determined by QEMU; usually if the feature is
            supported, default is on. In case there is a situation
            where this behavior is suboptimal, this attribute provides
            a way to force the feature off.
            <span class="since">Since 0.9.5 (QEMU and KVM only)</span>
            <b>In general you should leave this option alone, unless you
            are very certain you know what you are doing.</b>
          </li>
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3391 3392
          <li>
            The optional <code>copy_on_read</code> attribute controls
3393
            whether to copy read backing file into the image file. The
O
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            value can be either "on" or "off".
            Copy-on-read avoids accessing the same backing file sectors
            repeatedly and is useful when the backing file is over a slow
            network. By default copy-on-read is off.
            <span class='since'>Since 0.9.10 (QEMU and KVM only)</span>
          </li>
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          <li>
            The optional <code>discard</code> attribute controls whether
3402
            discard requests (also known as "trim" or "unmap") are
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            ignored or passed to the filesystem. The value can be either
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            "unmap" (allow the discard request to be passed) or "ignore"
            (ignore the discard request).
O
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            <span class='since'>Since 1.0.6 (QEMU and KVM only)</span>
          </li>
3408 3409 3410 3411 3412 3413 3414 3415 3416 3417
          <li>
            The optional <code>detect_zeroes</code> attribute controls whether
            to detect zero write requests.  The value can be "off", "on" or
            "unmap".  First two values turn the detection off and on,
            respectively.  The third value ("unmap") turns the detection on
            and additionally tries to discard such areas from the image based
            on the value of <code>discard</code> above (it will act as "on"
            if <code>discard</code> is set to "ignore").  NB enabling the
            detection is a compute intensive operation, but can save file
            space and/or time on slow media.
3418
            <span class='since'>Since 2.0.0</span>
3419
          </li>
3420 3421 3422 3423
          <li>
            The optional <code>iothread</code> attribute assigns the
            disk to an IOThread as defined by the range for the domain
            <a href="#elementsIOThreadsAllocation"><code>iothreads</code></a>
3424 3425 3426 3427 3428
            value. Multiple disks may be assigned to the same IOThread and
            are numbered from 1 to the domain iothreads value. Available
            for a disk device <code>target</code> configured to use "virtio"
            <code>bus</code> and "pci" or "ccw" <code>address</code> types.
            <span class='since'>Since 1.2.8 (QEMU 2.1)</span>
3429
          </li>
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          <li>
            The optional <code>queues</code> attribute specifies the number of
            virt queues for virtio-blk. (<span class="since">Since 3.9.0</span>)
          </li>
J
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          <li>
          For virtio disks,
          <a href="#elementsVirtio">Virtio-specific options</a> can also be
          set. (<span class="since">Since 3.5.0</span>)
          </li>
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        </ul>
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      </dd>
3441 3442 3443 3444 3445 3446
      <dt><code>backenddomain</code></dt>
      <dd>The optional <code>backenddomain</code> element allows specifying a
          backend domain (aka driver domain) hosting the disk.  Use the
          <code>name</code> attribute to specify the backend domain name.
          <span class="since">Since 1.2.13 (Xen only)</span>
      </dd>
3447 3448 3449
      <dt><code>boot</code></dt>
      <dd>Specifies that the disk is bootable. The <code>order</code>
        attribute determines the order in which devices will be tried during
3450 3451 3452 3453 3454 3455 3456
        boot sequence. On the S390 architecture only the first boot device is
        used. The optional <code>loadparm</code> attribute is an 8 character
        string which can be queried by guests on S390 via sclp or diag 308.
        Linux guests on S390 can use <code>loadparm</code> to select a boot
        entry. <span class="since">Since 3.5.0</span>
        The per-device <code>boot</code> elements cannot be used together
        with general boot elements in
3457 3458 3459
        <a href="#elementsOSBIOS">BIOS bootloader</a> section.
        <span class="since">Since 0.8.8</span>
      </dd>
3460
      <dt><code>encryption</code></dt>
3461 3462 3463 3464 3465
      <dd>Starting with <span class="since">libvirt 3.9.0</span> the
        <code>encryption</code> element is preferred to be a sub-element
        of the <code>source</code> element. If present, specifies how the
        volume is encrypted using "qcow". See the
        <a href="formatstorageencryption.html">Storage Encryption</a> page
3466 3467
        for more information.
      </dd>
3468 3469 3470
      <dt><code>readonly</code></dt>
      <dd>If present, this indicates the device cannot be modified by
        the guest.  For now, this is the default for disks with
3471
        attribute <code>device='cdrom'</code>.
3472
      </dd>
3473 3474 3475 3476 3477
      <dt><code>shareable</code></dt>
      <dd>If present, this indicates the device is expected to be shared
          between domains (assuming the hypervisor and OS support this),
          which means that caching should be deactivated for that device.
      </dd>
3478 3479 3480 3481 3482 3483 3484
      <dt><code>transient</code></dt>
      <dd>If present, this indicates that changes to the device
        contents should be reverted automatically when the guest
        exits.  With some hypervisors, marking a disk transient
        prevents the domain from participating in migration or
        snapshots. <span class="since">Since 0.9.5</span>
      </dd>
3485 3486
      <dt><code>serial</code></dt>
      <dd>If present, this specify serial number of virtual hard drive.
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          For example, it may look
          like <code>&lt;serial&gt;WD-WMAP9A966149&lt;/serial&gt;</code>.
3489 3490 3491
          Not supported for scsi-block devices, that is those using
          disk <code>type</code> 'block' using <code>device</code> 'lun'
          on <code>bus</code> 'scsi'.
3492 3493
          <span class="since">Since 0.7.1</span>
      </dd>
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3494 3495 3496
      <dt><code>wwn</code></dt>
      <dd>If present, this element specifies the WWN (World Wide Name)
        of a virtual hard disk or CD-ROM drive. It must be composed
3497
        of 16 hexadecimal digits.
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        <span class='since'>Since 0.10.1</span>
      </dd>
3500 3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511
      <dt><code>vendor</code></dt>
      <dd>If present, this element specifies the vendor of a virtual hard
        disk or CD-ROM device. It must not be longer than 8 printable
        characters.
        <span class='since'>Since 1.0.1</span>
      </dd>
      <dt><code>product</code></dt>
      <dd>If present, this element specifies the product of a virtual hard
        disk or CD-ROM device. It must not be longer than 16 printable
        characters.
        <span class='since'>Since 1.0.1</span>
      </dd>
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      <dt><code>address</code></dt>
      <dd>If present, the <code>address</code> element ties the disk
        to a given slot of a controller (the
        actual <code>&lt;controller&gt;</code> device can often be
        inferred by libvirt, although it can
        be <a href="#elementsControllers">explicitly specified</a>).
        The <code>type</code> attribute is mandatory, and is typically
        "pci" or "drive".  For a "pci" controller, additional
        attributes for <code>bus</code>, <code>slot</code>,
3521 3522 3523 3524 3525
        and <code>function</code> must be present, as well as
        optional <code>domain</code> and <code>multifunction</code>.
        Multifunction defaults to 'off'; any other value requires
        QEMU 0.1.3 and <span class="since">libvirt 0.9.7</span>.  For a
        "drive" controller, additional attributes
3526 3527 3528
        <code>controller</code>, <code>bus</code>, <code>target</code>
        (<span class="since">libvirt 0.9.11</span>), and <code>unit</code>
        are available, each defaulting to 0.
3529 3530
      </dd>
      <dt><code>auth</code></dt>
3531 3532 3533 3534 3535 3536 3537 3538
      <dd>Starting with <span class="since">libvirt 3.9.0</span> the
        <code>auth</code> element is preferred to be a sub-element of
        the <code>source</code> element. The element is still read and
        managed as a <code>disk</code> sub-element. It is invalid to use
        <code>auth</code> as both a sub-element of <code>disk</code>
        and <code>source</code>. The <code>auth</code> element was
        introduced as a <code>disk</code> sub-element in
        <span class="since">libvirt 0.9.7.</span>
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3539
      </dd>
J
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3540 3541 3542 3543 3544 3545 3546 3547 3548 3549 3550 3551 3552 3553 3554 3555 3556 3557 3558
      <dt><code>geometry</code></dt>
      <dd>The optional <code>geometry</code> element provides the
        ability to override geometry settings. This mostly useful for
        S390 DASD-disks or older DOS-disks.  <span class="since">0.10.0</span>
        <dl>
          <dt><code>cyls</code></dt>
          <dd>The <code>cyls</code> attribute is the
            number of cylinders. </dd>
          <dt><code>heads</code></dt>
          <dd>The <code>heads</code> attribute is the
            number of heads. </dd>
          <dt><code>secs</code></dt>
          <dd>The <code>secs</code> attribute is the
            number of sectors per track. </dd>
          <dt><code>trans</code></dt>
          <dd>The optional <code>trans</code> attribute is the
            BIOS-Translation-Modus (none, lba or auto)</dd>
        </dl>
      </dd>
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3559 3560
      <dt><code>blockio</code></dt>
      <dd>If present, the <code>blockio</code> element allows
3561 3562 3563 3564 3565 3566 3567 3568
        to override any of the block device properties listed below.
        <span class="since">Since 0.10.2 (QEMU and KVM)</span>
        <dl>
          <dt><code>logical_block_size</code></dt>
          <dd>The logical block size the disk will report to the guest
            OS. For Linux this would be the value returned by the
            BLKSSZGET ioctl and describes the smallest units for disk
            I/O.
3569
          </dd>
3570 3571 3572 3573 3574
          <dt><code>physical_block_size</code></dt>
          <dd>The physical block size the disk will report to the guest
            OS. For Linux this would be the value returned by the
            BLKPBSZGET ioctl and describes the disk's hardware sector
            size which can be relevant for the alignment of disk data.
3575
          </dd>
3576 3577
        </dl>
      </dd>
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3578 3579
    </dl>

3580
    <h4><a id="elementsFilesystems">Filesystems</a></h4>
3581 3582 3583 3584 3585 3586 3587

    <p>
      A directory on the host that can be accessed directly from the guest.
      <span class="since">since 0.3.3, since 0.8.5 for QEMU/KVM</span>
    </p>

<pre>
3588 3589 3590 3591 3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602 3603 3604 3605 3606
...
&lt;devices&gt;
  &lt;filesystem type='template'&gt;
    &lt;source name='my-vm-template'/&gt;
    &lt;target dir='/'/&gt;
  &lt;/filesystem&gt;
  &lt;filesystem type='mount' accessmode='passthrough'&gt;
    &lt;driver type='path' wrpolicy='immediate'/&gt;
    &lt;source dir='/export/to/guest'/&gt;
    &lt;target dir='/import/from/host'/&gt;
    &lt;readonly/&gt;
  &lt;/filesystem&gt;
  &lt;filesystem type='file' accessmode='passthrough'&gt;
    &lt;driver name='loop' type='raw'/&gt;
    &lt;driver type='path' wrpolicy='immediate'/&gt;
    &lt;source file='/export/to/guest.img'/&gt;
    &lt;target dir='/import/from/host'/&gt;
    &lt;readonly/&gt;
  &lt;/filesystem&gt;
3607
  ...
3608 3609
&lt;/devices&gt;
...</pre>
3610 3611 3612 3613 3614 3615 3616 3617 3618

    <dl>
      <dt><code>filesystem</code></dt>
      <dd>

      The filesystem attribute <code>type</code> specifies the type of the
      <code>source</code>. The possible values are:

        <dl>
3619
        <dt><code>mount</code></dt>
3620 3621 3622 3623
        <dd>
        A host directory to mount in the guest. Used by LXC,
        OpenVZ <span class="since">(since 0.6.2)</span>
        and QEMU/KVM <span class="since">(since 0.8.5)</span>.
3624
        This is the default <code>type</code> if one is not specified.
3625 3626 3627 3628
        This mode also has an optional
        sub-element <code>driver</code>, with an
        attribute <code>type='path'</code>
        or <code>type='handle'</code> <span class="since">(since
3629 3630 3631 3632 3633 3634
        0.9.7)</span>. The driver block has an optional attribute
        <code>wrpolicy</code> that further controls interaction with
        the host page cache; omitting the attribute gives default behavior,
        while the value <code>immediate</code> means that a host writeback
        is immediately triggered for all pages touched during a guest file
        write operation <span class="since">(since 0.9.10)</span>.
3635
        </dd>
3636
        <dt><code>template</code></dt>
3637 3638 3639
        <dd>
        OpenVZ filesystem template. Only used by OpenVZ driver.
        </dd>
3640
        <dt><code>file</code></dt>
3641
        <dd>
3642 3643 3644
        A host file will be treated as an image and mounted in
        the guest. The filesystem format will be autodetected.
        Only used by LXC driver.
3645
        </dd>
3646
        <dt><code>block</code></dt>
3647
        <dd>
3648 3649 3650
        A host block device to mount in the guest. The filesystem
        format will be autodetected. Only used by LXC driver
        <span class="since">(since 0.9.5)</span>.
3651
        </dd>
3652
        <dt><code>ram</code></dt>
3653 3654 3655
        <dd>
          An in-memory filesystem, using memory from the host OS.
          The source element has a single attribute <code>usage</code>
3656 3657
          which gives the memory usage limit in KiB, unless units
          are specified by the <code>units</code> attribute. Only used
3658 3659
          by LXC driver.
          <span class="since"> (since 0.9.13)</span></dd>
3660
        <dt><code>bind</code></dt>
3661 3662 3663 3664
        <dd>
          A directory inside the guest will be bound to another
          directory inside the guest. Only used by LXC driver
          <span class="since"> (since 0.9.13)</span></dd>
3665 3666
        </dl>

3667
      The filesystem block has an optional attribute <code>accessmode</code>
3668 3669 3670 3671 3672 3673
      which specifies the security mode for accessing the source
      <span class="since">(since 0.8.5)</span>. Currently this only works
      with <code>type='mount'</code> for the QEMU/KVM driver. The possible
      values are:

        <dl>
3674
        <dt><code>passthrough</code></dt>
3675 3676
        <dd>
        The <code>source</code> is accessed with the permissions of the
3677
        user inside the guest. This is the default <code>accessmode</code> if
3678 3679 3680
        one is not specified.
        <a href="http://lists.gnu.org/archive/html/qemu-devel/2010-05/msg02673.html">More info</a>
        </dd>
3681
        <dt><code>mapped</code></dt>
3682 3683 3684 3685 3686
        <dd>
        The <code>source</code> is accessed with the permissions of the
        hypervisor (QEMU process).
        <a href="http://lists.gnu.org/archive/html/qemu-devel/2010-05/msg02673.html">More info</a>
        </dd>
3687
        <dt><code>squash</code></dt>
3688 3689 3690 3691 3692 3693 3694 3695 3696 3697 3698
        <dd>
        Similar to 'passthrough', the exception is that failure of
        privileged operations like 'chown' are ignored. This makes a
        passthrough-like mode usable for people who run the hypervisor
        as non-root.
        <a href="http://lists.gnu.org/archive/html/qemu-devel/2010-09/msg00121.html">More info</a>
        </dd>
        </dl>

      </dd>

3699 3700 3701 3702 3703 3704 3705 3706 3707 3708 3709
      <dt><code>driver</code></dt>
      <dd>
        The optional driver element allows specifying further details
        related to the hypervisor driver used to provide the filesystem.
        <span class="since">Since 1.0.6</span>
        <ul>
          <li>
            If the hypervisor supports multiple backend drivers, then
            the <code>type</code> attribute selects the primary
            backend driver name, while the <code>format</code>
            attribute provides the format type. For example, LXC
3710 3711
            supports a type of "loop", with a format of "raw" or
            "nbd" with any format. QEMU supports a type of "path"
3712
            or "handle", but no formats. Virtuozzo driver supports
D
Dmitry Guryanov 已提交
3713
            a type of "ploop" with a format of "ploop".
3714
          </li>
3715 3716 3717 3718 3719
          <li>
          For virtio-backed devices,
          <a href="#elementsVirtio">Virtio-specific options</a> can also be
          set. (<span class="since">Since 3.5.0</span>)
          </li>
3720 3721 3722
        </ul>
      </dd>

3723 3724 3725 3726 3727
      <dt><code>source</code></dt>
      <dd>
        The resource on the host that is being accessed in the guest. The
        <code>name</code> attribute must be used with
        <code>type='template'</code>, and the <code>dir</code> attribute must
3728
        be used with <code>type='mount'</code>. The <code>usage</code> attribute
3729 3730
        is used with <code>type='ram'</code> to set the memory limit in KiB,
        unless units are specified by the <code>units</code> attribute.
3731 3732 3733 3734 3735 3736 3737 3738 3739 3740 3741 3742
      </dd>

      <dt><code>target</code></dt>
      <dd>
        Where the <code>source</code> can be accessed in the guest. For
        most drivers this is an automatic mount point, but for QEMU/KVM
        this is merely an arbitrary string tag that is exported to the
        guest as a hint for where to mount.
      </dd>

      <dt><code>readonly</code></dt>
      <dd>
3743
        Enables exporting filesystem as a readonly mount for guest, by
3744 3745
        default read-write access is given (currently only works for
        QEMU/KVM driver).
3746
      </dd>
3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757 3758 3759 3760

      <dt><code>space_hard_limit</code></dt>
      <dd>
        Maximum space available to this guest's filesystem.
        <span class="since">Since 0.9.13</span>
      </dd>

      <dt><code>space_soft_limit</code></dt>
      <dd>
        Maximum space available to this guest's filesystem. The container is
        permitted to exceed its soft limits for a grace period of time. Afterwards the
        hard limit is enforced.
        <span class="since">Since 0.9.13</span>
      </dd>
3761 3762
    </dl>

3763
    <h4><a id="elementsAddress">Device Addresses</a></h4>
3764 3765 3766 3767 3768 3769 3770 3771 3772 3773 3774 3775 3776 3777 3778 3779 3780 3781

    <p>
      Many devices have an optional <code>&lt;address&gt;</code>
      sub-element to describe where the device is placed on the
      virtual bus presented to the guest.  If an address (or any
      optional attribute within an address) is omitted on
      input, libvirt will generate an appropriate address; but an
      explicit address is required if more control over layout is
      required.  See below for device examples including an address
      element.
    </p>

    <p>
      Every address has a mandatory attribute <code>type</code> that
      describes which bus the device is on.  The choice of which
      address to use for a given device is constrained in part by the
      device and the architecture of the guest.  For example,
      a <code>&lt;disk&gt;</code> device
3782
      uses <code>type='drive'</code>, while
3783 3784 3785 3786 3787 3788 3789 3790
      a <code>&lt;console&gt;</code> device would
      use <code>type='pci'</code> on i686 or x86_64 guests,
      or <code>type='spapr-vio'</code> on PowerPC64 pseries guests.
      Each address type has further optional attributes that control
      where on the bus the device will be placed:
    </p>

    <dl>
3791
      <dt><code>pci</code></dt>
3792 3793 3794 3795 3796 3797 3798 3799 3800 3801 3802 3803
      <dd>PCI addresses have the following additional
        attributes: <code>domain</code> (a 2-byte hex integer, not
        currently used by qemu), <code>bus</code> (a hex value between
        0 and 0xff, inclusive), <code>slot</code> (a hex value between
        0x0 and 0x1f, inclusive), and <code>function</code> (a value
        between 0 and 7, inclusive).  Also available is
        the <code>multifunction</code> attribute, which controls
        turning on the multifunction bit for a particular
        slot/function in the PCI control register
        (<span class="since">since 0.9.7, requires QEMU
        0.13</span>). <code>multifunction</code> defaults to 'off',
        but should be set to 'on' for function 0 of a slot that will
3804 3805 3806 3807 3808 3809 3810
        have multiple functions used.<br/>
        <span class="since">Since 1.3.5</span>, some hypervisor
        drivers may accept an <code>&lt;address type='pci'/&gt;</code>
        element with no other attributes as an explicit request to
        assign a PCI address for the device rather than some other
        type of address that may also be appropriate for that same
        device (e.g. virtio-mmio).
3811
      </dd>
3812
      <dt><code>drive</code></dt>
3813 3814 3815
      <dd>Drive addresses have the following additional
        attributes: <code>controller</code> (a 2-digit controller
        number), <code>bus</code> (a 2-digit bus number),
3816
        <code>target</code> (a 2-digit target number),
3817 3818
        and <code>unit</code> (a 2-digit unit number on the bus).
      </dd>
3819
      <dt><code>virtio-serial</code></dt>
3820 3821 3822 3823 3824
      <dd>Each virtio-serial address has the following additional
        attributes: <code>controller</code> (a 2-digit controller
        number), <code>bus</code> (a 2-digit bus number),
        and <code>slot</code> (a 2-digit slot within the bus).
      </dd>
3825
      <dt><code>ccid</code></dt>
3826 3827 3828 3829
      <dd>A CCID address, for smart-cards, has the following
        additional attributes: <code>bus</code> (a 2-digit bus
        number), and <code>slot</code> attribute (a 2-digit slot
        within the bus).  <span class="since">Since 0.8.8.</span>
3830
      </dd>
3831
      <dt><code>usb</code></dt>
3832 3833 3834 3835 3836
      <dd>USB addresses have the following additional
        attributes: <code>bus</code> (a hex value between 0 and 0xfff,
        inclusive), and <code>port</code> (a dotted notation of up to
        four octets, such as 1.2 or 2.1.3.1).
      </dd>
3837
      <dt><code>spapr-vio</code></dt>
3838 3839 3840 3841 3842 3843 3844 3845
      <dd>On PowerPC pseries guests, devices can be assigned to the
        SPAPR-VIO bus.  It has a flat 64-bit address space; by
        convention, devices are generally assigned at a non-zero
        multiple of 0x1000, but other addresses are valid and
        permitted by libvirt.  Each address has the following
        additional attribute: <code>reg</code> (the hex value address
        of the starting register).  <span class="since">Since
        0.9.9.</span>
3846
      </dd>
3847
      <dt><code>ccw</code></dt>
B
Boris Fiuczynski 已提交
3848
      <dd>S390 guests with a <code>machine</code> value of
3849 3850 3851 3852 3853 3854 3855
        s390-ccw-virtio use the native CCW bus for I/O devices.
        CCW bus addresses have the following additional attributes:
        <code>cssid</code> (a hex value between 0 and 0xfe, inclusive),
        <code>ssid</code> (a value between 0 and 3, inclusive) and
        <code>devno</code> (a hex value between 0 and 0xffff, inclusive).
        Partially specified bus addresses are not allowed.
        If omitted, libvirt will assign a free bus address with
3856 3857
        cssid=0xfe and ssid=0. Virtio-ccw devices must have their cssid
        set to 0xfe.
3858
        <span class="since">Since 1.0.4</span>
3859
      </dd>
3860 3861 3862 3863 3864
      <dt><code>virtio-mmio</code></dt>
      <dd>This places the device on the virtio-mmio transport, which is
        currently only available for some <code>armv7l</code> and
        <code>aarch64</code> virtual machines. virtio-mmio addresses
        do not have any additional attributes.
3865 3866 3867 3868 3869 3870 3871
        <span class="since">Since 1.1.3</span><br/>
        If the guest architecture is <code>aarch64</code> and the machine
        type is <code>virt</code>, libvirt will automatically assign PCI
        addresses to devices; however, the presence of a single device
        with virtio-mmio address in the guest configuration will cause
        libvirt to assign virtio-mmio addresses to all further devices.
        <span class="since">Since 3.0.0</span>
3872
      </dd>
3873
      <dt><code>isa</code></dt>
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Hu Tao 已提交
3874 3875 3876 3877
      <dd>ISA addresses have the following additional
        attributes: <code>iobase</code> and <code>irq</code>.
        <span class="since">Since 1.2.1</span>
      </dd>
3878 3879
    </dl>

3880
    <h4><a id="elementsVirtio">Virtio-related options</a></h4>
3881 3882 3883 3884 3885 3886 3887 3888 3889 3890 3891 3892

    <p>
      QEMU's virtio devices have some attributes related to the virtio transport under
      the <code>driver</code> element:
      The <code>iommu</code> attribute enables the use of emulated IOMMU
      by the device. The attribute <code>ats</code> controls the Address
      Translation Service support for PCIe devices. This is needed to make use
      of IOTLB support (see <a href="#elementsIommu">IOMMU device</a>).
      Possible values are <code>on</code> or <code>off</code>.
      <span class="since">Since 3.5.0</span>
    </p>

3893
    <h4><a id="elementsControllers">Controllers</a></h4>
E
Eric Blake 已提交
3894 3895

    <p>
3896
      Depending on the guest architecture, some device buses can
3897 3898
      appear more than once, with a group of virtual devices tied to a
      virtual controller.  Normally, libvirt can automatically infer such
E
Eric Blake 已提交
3899
      controllers without requiring explicit XML markup, but sometimes
3900 3901 3902
      it is necessary to provide an explicit controller element, notably
      when planning the <a href="pci-hotplug.html">PCI topology</a>
      for guests where device hotplug is expected.
E
Eric Blake 已提交
3903 3904 3905
    </p>

<pre>
3906 3907 3908 3909 3910 3911 3912 3913 3914 3915 3916
...
&lt;devices&gt;
  &lt;controller type='ide' index='0'/&gt;
  &lt;controller type='virtio-serial' index='0' ports='16' vectors='4'/&gt;
  &lt;controller type='virtio-serial' index='1'&gt;
    &lt;address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/&gt;
  &lt;/controller&gt;
  &lt;controller type='scsi' index='0' model='virtio-scsi'&gt;
    &lt;driver iothread='4'/&gt;
    &lt;address type='pci' domain='0x0000' bus='0x00' slot='0x0b' function='0x0'/&gt;
  &lt;/controller&gt;
E
Eric Blake 已提交
3917
  ...
3918 3919
&lt;/devices&gt;
...</pre>
E
Eric Blake 已提交
3920 3921 3922

    <p>
      Each controller has a mandatory attribute <code>type</code>,
3923 3924
      which must be one of 'ide', 'fdc', 'scsi', 'sata', 'usb',
      'ccid', 'virtio-serial' or 'pci', and a mandatory
3925 3926
      attribute <code>index</code> which is the decimal integer
      describing in which order the bus controller is encountered (for
3927
      use in <code>controller</code> attributes of
3928 3929 3930 3931 3932
      <code>&lt;address&gt;</code> elements).
      <span class="since">Since 1.3.5</span> the index is optional; if
      not specified, it will be auto-assigned to be the lowest unused
      index for the given controller type. Some controller types have
      additional attributes that control specific features, such as:
3933 3934 3935 3936 3937 3938 3939 3940 3941 3942 3943 3944 3945 3946 3947 3948 3949
    </p>

      <dl>
        <dt><code>virtio-serial</code></dt>
        <dd>The <code>virtio-serial</code> controller has two additional
        optional attributes <code>ports</code> and <code>vectors</code>,
        which control how many devices can be connected through the
        controller.</dd>
        <dt><code>scsi</code></dt>
        <dd>A <code>scsi</code> controller has an optional attribute
        <code>model</code>, which is one of 'auto', 'buslogic', 'ibmvscsi',
        'lsilogic', 'lsisas1068', 'lsisas1078', 'virtio-scsi' or
        'vmpvscsi'.</dd>
        <dt><code>usb</code></dt>
        <dd>A <code>usb</code> controller has an optional attribute
        <code>model</code>, which is one of "piix3-uhci", "piix4-uhci",
        "ehci", "ich9-ehci1", "ich9-uhci1", "ich9-uhci2", "ich9-uhci3",
3950
        "vt82c686b-uhci", "pci-ohci", "nec-xhci", "qusb1" (xen pvusb
3951 3952
        with qemu backend, version 1.1), "qusb2" (xen pvusb with qemu
        backend, version 2.0) or "qemu-xhci". Additionally,
3953 3954 3955 3956 3957 3958 3959
         <span class="since">since 0.10.0</span>, if the USB bus needs to
         be explicitly disabled for the guest, <code>model='none'</code>
         may be used.  <span class="since">Since 1.0.5</span>, no default
         USB controller will be built on s390.
         <span class="since">Since 1.3.5</span>, USB controllers accept a
         <code>ports</code> attribute to configure how many devices can be
         connected to the controller.</dd>
3960 3961 3962 3963
        <dt><code>ide</code></dt>
        <dd><span class="since">Since 3.10.0</span> for the vbox driver, the
        <code>ide</code> controller has an optional attribute
        <code>model</code>, which is one of "piix3", "piix4" or "ich6".</dd>
3964 3965 3966 3967 3968
      </dl>

    <p>
      Note: The PowerPC64 "spapr-vio" addresses do not have an
      associated controller.
E
Eric Blake 已提交
3969 3970 3971 3972 3973 3974
    </p>

    <p>
      For controllers that are themselves devices on a PCI or USB bus,
      an optional sub-element <code>&lt;address&gt;</code> can specify
      the exact relationship of the controller to its master bus, with
3975
      semantics <a href="#elementsAddress">given above</a>.
E
Eric Blake 已提交
3976 3977
    </p>

3978 3979
    <p>
      An optional sub-element <code>driver</code> can specify the driver
3980
      specific options:
3981
    </p>
3982 3983 3984 3985 3986 3987 3988 3989 3990 3991 3992 3993 3994 3995 3996 3997 3998 3999 4000 4001 4002 4003 4004
    <dl>
      <dt><code>queues</code></dt>
      <dd>
        The optional <code>queues</code> attribute specifies the number of
        queues for the controller. For best performance, it's recommended to
        specify a value matching the number of vCPUs.
        <span class="since">Since 1.0.5 (QEMU and KVM only)</span>
      </dd>
      <dt><code>cmd_per_lun</code></dt>
      <dd>
        The optional <code>cmd_per_lun</code> attribute specifies the maximum
        number of commands that can be queued on devices controlled by the
        host.
        <span class="since">Since 1.2.7 (QEMU and KVM only)</span>
      </dd>
      <dt><code>max_sectors</code></dt>
      <dd>
        The optional <code>max_sectors</code> attribute specifies the maximum
        amount of data in bytes that will be transferred to or from the device
        in a single command. The transfer length is measured in sectors, where
        a sector is 512 bytes.
        <span class="since">Since 1.2.7 (QEMU and KVM only)</span>
      </dd>
4005 4006 4007 4008 4009 4010 4011 4012
      <dt><code>ioeventfd</code></dt>
      <dd>
        The optional <code>ioeventfd</code> attribute specifies
        whether the controller should use
        <a href='https://patchwork.kernel.org/patch/43390/'>
        I/O asynchronous handling</a> or not.  Accepted values are
        "on" and "off". <span class="since">Since 1.2.18</span>
      </dd>
4013 4014 4015 4016 4017 4018 4019 4020 4021 4022 4023 4024 4025 4026 4027 4028 4029
      <dt><code>iothread</code></dt>
      <dd>
        Supported for controller type <code>scsi</code> using model
        <code>virtio-scsi</code> for <code>address</code> types
        <code>pci</code> and <code>ccw</code>
        <span class="since">since 1.3.5 (QEMU 2.4)</span>.

        The optional <code>iothread</code> attribute assigns the controller
        to an IOThread as defined by the range for the domain
        <a href="#elementsIOThreadsAllocation"><code>iothreads</code></a>
        value. Each SCSI <code>disk</code> assigned to use the specified
        <code>controller</code> will utilize the same IOThread. If a specific
        IOThread is desired for a specific SCSI <code>disk</code>, then
        multiple controllers must be defined each having a specific
        <code>iothread</code> value. The <code>iothread</code> value
        must be within the range 1 to the domain iothreads value.
      </dd>
4030 4031 4032 4033 4034 4035
      <dt>virtio options</dt>
      <dd>
        For virtio controllers,
        <a href="#elementsVirtio">Virtio-specific options</a> can also be
        set. (<span class="since">Since 3.5.0</span>)
      </dd>
4036
    </dl>
4037 4038 4039 4040 4041 4042
    <p>
      USB companion controllers have an optional
      sub-element <code>&lt;master&gt;</code> to specify the exact
      relationship of the companion to its master controller.
      A companion controller is on the same bus as its master, so
      the companion <code>index</code> value should be equal.
4043 4044 4045 4046 4047
      Not all controller models can be used as companion controllers
      and libvirt might provide some sensible defaults (settings
      of <code>master startport</code> and <code>function</code> of an
      address) for some particular models.
      Preferred companion controllers are <code>ich-uhci[123]</code>.
4048 4049 4050
    </p>

<pre>
4051 4052 4053 4054 4055 4056 4057 4058 4059
...
&lt;devices&gt;
  &lt;controller type='usb' index='0' model='ich9-ehci1'&gt;
    &lt;address type='pci' domain='0' bus='0' slot='4' function='7'/&gt;
  &lt;/controller&gt;
  &lt;controller type='usb' index='0' model='ich9-uhci1'&gt;
    &lt;master startport='0'/&gt;
    &lt;address type='pci' domain='0' bus='0' slot='4' function='0' multifunction='on'/&gt;
  &lt;/controller&gt;
4060
  ...
4061 4062
&lt;/devices&gt;
...</pre>
J
Ján Tomko 已提交
4063 4064

    <p>
4065 4066 4067 4068 4069 4070 4071 4072 4073 4074 4075 4076 4077 4078 4079 4080 4081 4082 4083 4084 4085
      PCI controllers have an optional <code>model</code> attribute; possible
      values for this attribute are
    </p>
    <ul>
      <li>
        <code>pci-root</code>, <code>pci-bridge</code>
        (<span class="since">since 1.0.5</span>)
      </li>
      <li>
        <code>pcie-root</code>, <code>dmi-to-pci-bridge</code>
        (<span class="since">since 1.1.2</span>)
      </li>
      <li>
        <code>pcie-root-port</code>, <code>pcie-switch-upstream-port</code>,
        <code>pcie-switch-downstream-port</code>
        (<span class="since">since 1.2.19</span>)
      </li>
      <li>
        <code>pci-expander-bus</code>, <code>pcie-expander-bus</code>
        (<span class="since">since 1.3.4</span>)
      </li>
4086 4087 4088 4089
      <li>
        <code>pcie-to-pci-bridge</code>
        (<span class="since">since 4.3.0</span>)
      </li>
4090 4091 4092
    </ul>
    <p>
      The root controllers (<code>pci-root</code>
4093 4094 4095
      and <code>pcie-root</code>) have an
      optional <code>pcihole64</code> element specifying how big (in
      kilobytes, or in the unit specified by <code>pcihole64</code>'s
4096 4097 4098 4099 4100
      <code>unit</code> attribute) the 64-bit PCI hole should be. Some guests (like
      Windows XP or Windows Server 2003) might crash when QEMU and Seabios
      are recent enough to support 64-bit PCI holes, unless this is disabled
      (set to 0). <span class="since">Since 1.1.2 (QEMU only)</span>
    </p>
4101 4102 4103 4104 4105 4106 4107 4108 4109 4110 4111 4112 4113
    <p>
      PCI controllers also have an optional
      subelement <code>&lt;model&gt;</code> with an attribute
      <code>name</code>. The name attribute holds the name of the
      specific device that qemu is emulating (e.g. "i82801b11-bridge")
      rather than simply the class of device ("dmi-to-pci-bridge",
      "pci-bridge"), which is set in the controller element's
      model <b>attribute</b>.  In almost all cases, you should not
      manually add a <code>&lt;model&gt;</code> subelement to a
      controller, nor should you modify one that is automatically
      generated by libvirt. <span class="since">Since 1.2.19 (QEMU
      only).</span>
    </p>
4114 4115
    <p>
      PCI controllers also have an optional
4116 4117 4118
      subelement <code>&lt;target&gt;</code> with the attributes and
      subelements listed below. These are configurable items that 1)
      are visible to the guest OS so must be preserved for guest ABI
4119 4120 4121 4122 4123 4124 4125 4126 4127 4128 4129 4130 4131 4132 4133 4134
      compatibility, and 2) are usually left to default values or
      derived automatically by libvirt. In almost all cases, you
      should not manually add a <code>&lt;target&gt;</code> subelement
      to a controller, nor should you modify the values in the those
      that are automatically generated by
      libvirt. <span class="since">Since 1.2.19 (QEMU only).</span>
    </p>
    <dl>
      <dt><code>chassisNr</code></dt>
      <dd>
        PCI controllers that have attribute model="pci-bridge", can
        also have a <code>chassisNr</code> attribute in
        the <code>&lt;target&gt;</code> subelement, which is used to
        control QEMU's "chassis_nr" option for the pci-bridge device
        (normally libvirt automatically sets this to the same value as
        the index attribute of the pci controller). If set, chassisNr
4135
        must be between 1 and 255.
4136
      </dd>
4137 4138
      <dt><code>chassis</code></dt>
      <dd>
4139 4140
        pcie-root-port and pcie-switch-downstream-port controllers can
        also have a <code>chassis</code> attribute in
4141 4142 4143 4144 4145 4146 4147
        the <code>&lt;target&gt;</code> subelement, which is used to
        set the controller's "chassis" configuration value, which is
        visible to the virtual machine. If set, chassis must be
        between 0 and 255.
      </dd>
      <dt><code>port</code></dt>
      <dd>
4148 4149 4150
        pcie-root-port and pcie-switch-downstream-port controllers can
        also have a <code>port</code> attribute in
        the <code>&lt;target&gt;</code> subelement, which
4151 4152 4153 4154
        is used to set the controller's "port" configuration value,
        which is visible to the virtual machine. If set, port must be
        between 0 and 255.
      </dd>
4155 4156
      <dt><code>busNr</code></dt>
      <dd>
4157
        pci-expander-bus and pcie-expander-bus controllers can have an
4158 4159 4160 4161 4162 4163 4164 4165 4166 4167 4168 4169 4170 4171
        optional <code>busNr</code> attribute (1-254). This will be
        the bus number of the new bus; All bus numbers between that
        specified and 255 will be available only for assignment to
        PCI/PCIe controllers plugged into the hierarchy starting with
        this expander bus, and bus numbers less than the specified
        value will be available to the next lower expander-bus (or the
        root-bus if there are no lower expander buses). If you do not
        specify a busNumber, libvirt will find the lowest existing
        busNumber in all other expander buses (or use 256 if there are
        no others) and auto-assign the busNr of that found bus - 2,
        which provides one bus number for the pci-expander-bus and one
        for the pci-bridge that is automatically attached to it (if
        you plan on adding more pci-bridges to the hierarchy of the
        bus, you should manually set busNr to a lower value).
4172 4173 4174 4175 4176 4177 4178
        <p>
          A similar algorithm is used for automatically determining
          the busNr attribute for pcie-expander-bus, but since the
          pcie-expander-bus doesn't have any built-in pci-bridge, the
          2nd bus-number is just being reserved for the pcie-root-port
          that must necessarily be connected to the bus in order to
          actually plug in an endpoint device. If you intend to plug
4179 4180 4181 4182 4183 4184 4185
          multiple devices into a pcie-expander-bus, you must connect
          a pcie-switch-upstream-port to the pcie-root-port that is
          plugged into the pcie-expander-bus, and multiple
          pcie-switch-downstream-ports to the
          pcie-switch-upstream-port, and of course for this to work
          properly, you will need to decrease the pcie-expander-bus'
          busNr accordingly so that there are enough unused bus
V
Ville Skyttä 已提交
4186
          numbers above it to accommodate giving out one bus number for
4187 4188 4189
          the upstream-port and one for each downstream-port (in
          addition to the pcie-root-port and the pcie-expander-bus
          itself).
4190
        </p>
4191
      </dd>
4192
      <dt><code>node</code></dt>
4193
      <dd>
4194 4195 4196 4197
        Some PCI controllers (<code>pci-expander-bus</code> for the pc
        machine type, <code>pcie-expander-bus</code> for the q35 machine
        type and, <span class="since">since 3.6.0</span>,
        <code>pci-root</code> for the pseries machine type) can have an
4198 4199 4200 4201 4202 4203 4204 4205
        optional <code>&lt;node&gt;</code> subelement within
        the <code>&lt;target&gt;</code> subelement, which is used to
        set the NUMA node reported to the guest OS for that bus - the
        guest OS will then know that all devices on that bus are a
        part of the specified NUMA node (it is up to the user of the
        libvirt API to attach host devices to the correct
        pci-expander-bus when assigning them to the domain).
      </dd>
4206 4207 4208 4209 4210 4211
      <dt><code>index</code></dt>
      <dd>
        pci-root controllers for pSeries guests use this attribute to
        record the order they will show up in the guest.
        <span class="since">Since 3.6.0</span>
      </dd>
4212
    </dl>
4213
    <p>
L
Laine Stump 已提交
4214
      For machine types which provide an implicit PCI bus, the pci-root
J
Ján Tomko 已提交
4215
      controller with index=0 is auto-added and required to use PCI devices.
L
Laine Stump 已提交
4216
      pci-root has no address.
4217 4218 4219
      PCI bridges are auto-added if there are too many devices to fit on
      the one bus provided by pci-root, or a PCI bus number greater than zero
      was specified.
J
Ján Tomko 已提交
4220 4221 4222 4223 4224 4225
      PCI bridges can also be specified manually, but their addresses should
      only refer to PCI buses provided by already specified PCI controllers.
      Leaving gaps in the PCI controller indexes might lead to an invalid
      configuration.
    </p>
<pre>
4226 4227 4228 4229 4230 4231 4232 4233
...
&lt;devices&gt;
  &lt;controller type='pci' index='0' model='pci-root'/&gt;
  &lt;controller type='pci' index='1' model='pci-bridge'&gt;
    &lt;address type='pci' domain='0' bus='0' slot='5' function='0' multifunction='off'/&gt;
  &lt;/controller&gt;
&lt;/devices&gt;
...</pre>
L
Laine Stump 已提交
4234 4235 4236 4237 4238 4239

    <p>
      For machine types which provide an implicit PCI Express (PCIe)
      bus (for example, the machine types based on the Q35 chipset),
      the pcie-root controller with index=0 is auto-added to the
      domain's configuration. pcie-root has also no address, provides
4240 4241 4242 4243
      31 slots (numbered 1-31) that can be used to attach PCIe or PCI
      devices (although libvirt will never auto-assign a PCI device to
      a PCIe slot, it will allow manual specification of such an
      assignment). Devices connected to pcie-root cannot be
4244 4245 4246 4247 4248 4249 4250 4251
      hotplugged. If traditional PCI devices are present in the guest
      configuration, a <code>pcie-to-pci-bridge</code> controller will
      automatically be added: this controller, which plugs into a
      <code>pcie-root-port</code>, provides 31 usable PCI slots (1-31) with
      hotplug support (<span class="since">since 4.3.0</span>). If the QEMU
      binary doesn't support the corresponding device, then a
      <code>dmi-to-pci-bridge</code> controller will be added instead,
      usually at the defacto standard location of slot=0x1e. A
4252 4253 4254
      dmi-to-pci-bridge controller plugs into a PCIe slot (as provided
      by pcie-root), and itself provides 31 standard PCI slots (which
      also do not support device hotplug). In order to have
4255 4256 4257
      hot-pluggable PCI slots in the guest system, a pci-bridge
      controller will also be automatically created and connected to
      one of the slots of the auto-created dmi-to-pci-bridge
4258
      controller; all guest PCI devices with addresses that are
4259 4260
      auto-determined by libvirt will be placed on this pci-bridge
      device.  (<span class="since">since 1.1.2</span>).
L
Laine Stump 已提交
4261
    </p>
4262 4263
    <p>
      Domains with an implicit pcie-root can also add controllers
4264 4265 4266 4267 4268 4269 4270 4271 4272 4273 4274 4275 4276 4277 4278 4279 4280 4281 4282 4283 4284 4285 4286 4287 4288 4289
      with <code>model='pcie-root-port'</code>,
      <code>model='pcie-switch-upstream-port'</code>,
      and <code>model='pcie-switch-downstream-port'</code>. pcie-root-port
      is a simple type of bridge device that can connect only to one
      of the 31 slots on the pcie-root bus on its upstream side, and
      makes a single (PCIe, hotpluggable) port available on the
      downstream side (at slot='0'). pcie-root-port can be used to
      provide a single slot to later hotplug a PCIe device (but is not
      itself hotpluggable - it must be in the configuration when the
      domain is started).
      (<span class="since">since 1.2.19</span>)
    </p>
    <p>
      pcie-switch-upstream-port is a more flexible (but also more
      complex) device that can only plug into a pcie-root-port or
      pcie-switch-downstream-port on the upstream side (and only
      before the domain is started - it is not hot-pluggable), and
      provides 32 ports on the downstream side (slot='0' - slot='31')
      that accept only pcie-switch-downstream-port devices; each
      pcie-switch-downstream-port device can only plug into a
      pcie-switch-upstream-port on its upstream side (again, not
      hot-pluggable), and on its downstream side provides a single
      hotpluggable pcie port that can accept any standard pci or pcie
      device (or another pcie-switch-upstream-port), i.e. identical in
      function to a pcie-root-port.  (<span class="since">since
      1.2.19</span>)
4290
    </p>
L
Laine Stump 已提交
4291
<pre>
4292 4293 4294 4295 4296 4297 4298 4299 4300 4301 4302
...
&lt;devices&gt;
  &lt;controller type='pci' index='0' model='pcie-root'/&gt;
  &lt;controller type='pci' index='1' model='dmi-to-pci-bridge'&gt;
    &lt;address type='pci' domain='0' bus='0' slot='0xe' function='0'/&gt;
  &lt;/controller&gt;
  &lt;controller type='pci' index='2' model='pci-bridge'&gt;
    &lt;address type='pci' domain='0' bus='1' slot='1' function='0'/&gt;
  &lt;/controller&gt;
&lt;/devices&gt;
...</pre>
4303

4304
    <h4><a id="elementsLease">Device leases</a></h4>
4305 4306 4307 4308 4309 4310 4311 4312

    <p>
      When using a lock manager, it may be desirable to record device leases
      against a VM. The lock manager will ensure the VM won't start unless
      the leases can be acquired.
    </p>

<pre>
4313 4314
...
&lt;devices&gt;
4315
  ...
4316 4317 4318 4319 4320 4321 4322 4323
  &lt;lease&gt;
    &lt;lockspace&gt;somearea&lt;/lockspace&gt;
    &lt;key&gt;somekey&lt;/key&gt;
    &lt;target path='/some/lease/path' offset='1024'/&gt;
  &lt;/lease&gt;
  ...
&lt;/devices&gt;
...</pre>
4324 4325

    <dl>
4326
      <dt><code>lockspace</code></dt>
4327 4328 4329 4330
      <dd>This is an arbitrary string, identifying the lockspace
        within which the key is held. Lock managers may impose
        extra restrictions on the format, or length of the lockspace
        name.</dd>
4331
      <dt><code>key</code></dt>
4332 4333 4334 4335
      <dd>This is an arbitrary string, uniquely identifying the
        lease to be acquired. Lock managers may impose extra
        restrictions on the format, or length of the key.
      </dd>
4336
      <dt><code>target</code></dt>
4337 4338 4339
      <dd>This is the fully qualified path of the file associated
        with the lockspace. The offset specifies where the lease
        is stored within the file. If the lock manager does not
V
Ville Skyttä 已提交
4340
        require an offset, just pass 0.
4341 4342
      </dd>
    </dl>
E
Eric Blake 已提交
4343

4344
    <h4><a id="elementsHostDev">Host device assignment</a></h4>
4345

4346
    <h5><a id="elementsHostDevSubsys">USB / PCI / SCSI devices</a></h5>
4347 4348

    <p>
H
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4349
      USB, PCI and SCSI devices attached to the host can be passed through
4350
      to the guest using the <code>hostdev</code> element.
H
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4351 4352
      <span class="since">since after 0.4.4 for USB, 0.6.0 for PCI(KVM only)
        and 1.0.6 for SCSI(KVM only)</span>:
4353 4354
    </p>

4355
<pre>
4356 4357 4358 4359 4360 4361 4362 4363 4364 4365 4366
...
&lt;devices&gt;
  &lt;hostdev mode='subsystem' type='usb'&gt;
    &lt;source startupPolicy='optional'&gt;
      &lt;vendor id='0x1234'/&gt;
      &lt;product id='0xbeef'/&gt;
    &lt;/source&gt;
    &lt;boot order='2'/&gt;
  &lt;/hostdev&gt;
&lt;/devices&gt;
...</pre>
4367

4368
    <p>or:</p>
4369 4370

<pre>
4371 4372 4373 4374 4375 4376 4377 4378 4379 4380 4381
...
&lt;devices&gt;
  &lt;hostdev mode='subsystem' type='pci' managed='yes'&gt;
    &lt;source&gt;
      &lt;address domain='0x0000' bus='0x06' slot='0x02' function='0x0'/&gt;
    &lt;/source&gt;
    &lt;boot order='1'/&gt;
    &lt;rom bar='on' file='/etc/fake/boot.bin'/&gt;
  &lt;/hostdev&gt;
&lt;/devices&gt;
...</pre>
H
Han Cheng 已提交
4382 4383 4384 4385

    <p>or:</p>

<pre>
4386 4387 4388 4389 4390 4391 4392 4393 4394 4395 4396 4397
...
&lt;devices&gt;
  &lt;hostdev mode='subsystem' type='scsi' sgio='filtered' rawio='yes'&gt;
    &lt;source&gt;
      &lt;adapter name='scsi_host0'/&gt;
      &lt;address bus='0' target='0' unit='0'/&gt;
    &lt;/source&gt;
    &lt;readonly/&gt;
    &lt;address type='drive' controller='0' bus='0' target='0' unit='0'/&gt;
  &lt;/hostdev&gt;
&lt;/devices&gt;
...</pre>
4398

J
John Ferlan 已提交
4399 4400 4401 4402

    <p>or:</p>

<pre>
4403 4404 4405 4406 4407 4408 4409 4410 4411 4412 4413 4414 4415
...
&lt;devices&gt;
  &lt;hostdev mode='subsystem' type='scsi'&gt;
    &lt;source protocol='iscsi' name='iqn.2014-08.com.example:iscsi-nopool/1'&gt;
      &lt;host name='example.com' port='3260'/&gt;
      &lt;auth username='myuser'&gt;
        &lt;secret type='iscsi' usage='libvirtiscsi'/&gt;
      &lt;/auth&gt;
    &lt;/source&gt;
    &lt;address type='drive' controller='0' bus='0' target='0' unit='0'/&gt;
  &lt;/hostdev&gt;
&lt;/devices&gt;
...</pre>
J
John Ferlan 已提交
4416

4417 4418 4419 4420 4421 4422 4423 4424 4425
    <p>or:</p>

<pre>
  ...
  &lt;devices&gt;
    &lt;hostdev mode='subsystem' type='scsi_host'&gt;
      &lt;source protocol='vhost' wwpn='naa.50014057667280d8'/&gt;
    &lt;/hostdev&gt;
  &lt;/devices&gt;
4426 4427 4428 4429 4430 4431 4432 4433 4434
  ...</pre>

    <p>or:</p>

<pre>
  ...
  &lt;devices&gt;
    &lt;hostdev mode='subsystem' type='mdev' model='vfio-pci'&gt;
    &lt;source&gt;
4435
      &lt;address uuid='c2177883-f1bb-47f0-914d-32a22e3a8804'/&gt;
4436 4437
    &lt;/source&gt;
    &lt;/hostdev&gt;
4438 4439 4440 4441 4442 4443
    &lt;hostdev mode='subsystem' type='mdev' model='vfio-ccw'&gt;
    &lt;source&gt;
      &lt;address uuid='9063cba3-ecef-47b6-abcf-3fef4fdcad85'/&gt;
    &lt;/source&gt;
    &lt;address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0001'/&gt;
    &lt;/hostdev&gt;
4444
  &lt;/devices&gt;
4445 4446
  ...</pre>

4447 4448 4449
    <dl>
      <dt><code>hostdev</code></dt>
      <dd>The <code>hostdev</code> element is the main container for describing
J
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4450 4451 4452 4453
        host devices. For each device, the <code>mode</code> is always
        "subsystem" and the <code>type</code> is one of the following values
        with additional attributes noted.
        <dl>
4454
          <dt><code>usb</code></dt>
4455 4456 4457
          <dd>USB devices are detached from the host on guest startup
            and reattached after the guest exits or the device is
            hot-unplugged.
J
John Ferlan 已提交
4458
          </dd>
4459
          <dt><code>pci</code></dt>
J
John Ferlan 已提交
4460 4461 4462
          <dd>For PCI devices, when <code>managed</code> is "yes" it is
            detached from the host before being passed on to the guest
            and reattached to the host after the guest exits. If
4463 4464 4465 4466 4467 4468
            <code>managed</code> is omitted or "no", the user is
            responsible to call <code>virNodeDeviceDetachFlags</code>
            (or <code>virsh nodedev-detach</code> before starting the guest
            or hot-plugging the device and <code>virNodeDeviceReAttach</code>
            (or <code>virsh nodedev-reattach</code>) after hot-unplug or
            stopping the guest.
J
John Ferlan 已提交
4469
          </dd>
4470
          <dt><code>scsi</code></dt>
J
John Ferlan 已提交
4471
          <dd>For SCSI devices, user is responsible to make sure the device
4472 4473 4474 4475 4476 4477
            is not used by host. If supported by the hypervisor and OS, the
            optional <code>sgio</code> (<span class="since">since 1.0.6</span>)
            attribute indicates whether unprivileged SG_IO commands are
            filtered for the disk. Valid settings are "filtered" or
            "unfiltered", where the default is "filtered".
            The optional <code>rawio</code>
4478 4479 4480 4481 4482 4483
            (<span class="since">since 1.2.9</span>) attribute indicates
            whether the lun needs the rawio capability. Valid settings are
            "yes" or "no". See the rawio description within the
            <a href="#elementsDisks">disk</a> section.
            If a disk lun in the domain already has the rawio capability,
            then this setting not required.
J
John Ferlan 已提交
4484
          </dd>
4485 4486 4487 4488 4489 4490
          <dt><code>scsi_host</code></dt>
          <dd><span class="since">since 2.5.0</span>For SCSI devices, user
            is responsible to make sure the device is not used by host. This
            <code>type</code> passes all LUNs presented by a single HBA to
            the guest.
          </dd>
4491 4492 4493 4494
          <dt><code>mdev</code></dt>
          <dd>For mediated devices (<span class="since">Since 3.2.0</span>)
          the <code>model</code> attribute specifies the device API which
          determines how the host's vfio driver will expose the device to the
4495 4496 4497 4498 4499 4500 4501
          guest. Currently, <code>model='vfio-pci'</code> and
          <code>model='vfio-ccw'</code> (<span class="since">Since 4.4.0</span>)
          is supported. Refer <a href="drvnodedev.html#MDEV">MDEV</a> to create
          a mediated device on the host. There are also some implications on the
          usage of guest's address type depending on the <code>model</code>
          attribute, see the <code>address</code> element below.
          </dd>
J
John Ferlan 已提交
4502
        </dl>
4503
        <p>
4504 4505 4506 4507 4508 4509
          Note: The <code>managed</code> attribute is only used with
          <code>type='pci'</code> and is ignored by all the other device types,
          thus setting <code>managed</code> explicitly with other than a PCI
          device has the same effect as omitting it. Similarly,
          <code>model</code> attribute is only supported by mediated devices and
          ignored by all other device types.
4510
        </p>
O
Osier Yang 已提交
4511
      </dd>
4512
      <dt><code>source</code></dt>
J
John Ferlan 已提交
4513 4514 4515
      <dd>The source element describes the device as seen from the host using
        the following mechanism to describe:
        <dl>
4516
          <dt><code>usb</code></dt>
J
John Ferlan 已提交
4517 4518 4519 4520 4521 4522 4523 4524 4525 4526 4527 4528 4529 4530 4531 4532 4533 4534 4535 4536 4537 4538 4539 4540 4541 4542 4543
          <dd>The USB device can either be addressed by vendor / product id
            using the <code>vendor</code> and <code>product</code> elements
            or by the device's address on the host using the
            <code>address</code> element.
            <p>
            <span class="since">Since 1.0.0</span>, the <code>source</code>
            element of USB devices may contain <code>startupPolicy</code>
            attribute which can be used to define policy what to do if the
            specified host USB device is not found. The attribute accepts
            the following values:
            </p>
            <table class="top_table">
              <tr>
                <td> mandatory </td>
                <td> fail if missing for any reason (the default) </td>
              </tr>
              <tr>
                <td> requisite </td>
                <td> fail if missing on boot up,
                     drop if missing on migrate/restore/revert </td>
              </tr>
              <tr>
                <td> optional </td>
                <td> drop if missing at any start attempt </td>
              </tr>
            </table>
          </dd>
4544
          <dt><code>pci</code></dt>
J
John Ferlan 已提交
4545 4546
          <dd>PCI devices can only be described by their <code>address</code>.
          </dd>
4547
          <dt><code>scsi</code></dt>
J
John Ferlan 已提交
4548
          <dd>SCSI devices are described by both the <code>adapter</code>
4549 4550 4551 4552 4553 4554 4555 4556
            and <code>address</code> elements. The <code>address</code>
            element includes a <code>bus</code> attribute (a 2-digit bus
            number), a <code>target</code> attribute (a 10-digit target
            number), and a <code>unit</code> attribute (a 20-digit unit
            number on the bus). Not all hypervisors support larger
            <code>target</code> and <code>unit</code> values. It is up
            to each hypervisor to determine the maximum value supported
            for the adapter.
J
John Ferlan 已提交
4557 4558 4559 4560 4561 4562 4563 4564 4565 4566
            <p>
            <span class="since">Since 1.2.8</span>, the <code>source</code>
            element of a SCSI device may contain the <code>protocol</code>
            attribute. When the attribute is set to "iscsi", the host
            device XML follows the network <a href="#elementsDisks">disk</a>
            device using the same <code>name</code> attribute and optionally
            using the <code>auth</code> element to provide the authentication
            credentials to the iSCSI server.
            </p>
          </dd>
4567 4568 4569 4570 4571 4572 4573
          <dt><code>scsi_host</code></dt>
          <dd><span class="since">Since 2.5.0</span>, multiple LUNs behind a
            single SCSI HBA are described by a <code>protocol</code>
            attribute set to "vhost" and a <code>wwpn</code> attribute that
            is the vhost_scsi wwpn (16 hexadecimal digits with a prefix of
            "naa.") established in the host configfs.
          </dd>
4574 4575 4576 4577 4578 4579
          <dt><code>mdev</code></dt>
          <dd>Mediated devices (<span class="since">Since 3.2.0</span>) are
            described by the <code>address</code> element. The
            <code>address</code> element contains a single mandatory attribute
            <code>uuid</code>.
          </dd>
J
John Ferlan 已提交
4580
        </dl>
4581
      </dd>
4582 4583 4584 4585 4586
      <dt><code>vendor</code>, <code>product</code></dt>
      <dd>The <code>vendor</code> and <code>product</code> elements each have an
      <code>id</code> attribute that specifies the USB vendor and product id.
      The ids can be given in decimal, hexadecimal (starting with 0x) or
      octal (starting with 0) form.</dd>
4587 4588 4589 4590 4591 4592
      <dt><code>boot</code></dt>
      <dd>Specifies that the device is bootable. The <code>order</code>
      attribute determines the order in which devices will be tried during
      boot sequence. The per-device <code>boot</code> elements cannot be
      used together with general boot elements in
      <a href="#elementsOSBIOS">BIOS bootloader</a> section.
4593 4594
      <span class="since">Since 0.8.8</span> for PCI devices,
      <span class="since">Since 1.0.1</span> for USB devices.
4595
      </dd>
4596 4597
      <dt><code>rom</code></dt>
      <dd>The <code>rom</code> element is used to change how a PCI
4598
        device's ROM is presented to the guest. The optional <code>bar</code>
4599 4600 4601 4602 4603 4604 4605
        attribute can be set to "on" or "off", and determines whether
        or not the device's ROM will be visible in the guest's memory
        map. (In PCI documentation, the "rombar" setting controls the
        presence of the Base Address Register for the ROM). If no rom
        bar is specified, the qemu default will be used (older
        versions of qemu used a default of "off", while newer qemus
        have a default of "on"). <span class="since">Since
4606
        0.9.7 (QEMU and KVM only)</span>. The optional
4607
        <code>file</code> attribute contains an absolute path to a binary file
4608 4609 4610 4611 4612
        to be presented to the guest as the device's ROM BIOS. This
        can be useful, for example, to provide a PXE boot ROM for a
        virtual function of an sr-iov capable ethernet device (which
        has no boot ROMs for the VFs).
        <span class="since">Since 0.9.10 (QEMU and KVM only)</span>.
4613 4614 4615 4616 4617 4618
        The optional <code>enabled</code> attribute can be set to
        <code>no</code> to disable PCI ROM loading completely for the device;
        if PCI ROM loading is disabled through this attribute, attempts to
        tweak the loading process further using the <code>bar</code> or
        <code>file</code> attributes will be rejected.
        <span class="since">Since 4.3.0 (QEMU and KVM only)</span>.
4619
      </dd>
4620
      <dt><code>address</code></dt>
4621 4622 4623 4624 4625
      <dd>The <code>address</code> element for USB devices has a
      <code>bus</code> and <code>device</code> attribute to specify the
      USB bus and device number the device appears at on the host.
      The values of these attributes can be given in decimal, hexadecimal
      (starting with 0x) or octal (starting with 0) form.
4626
      For PCI devices the element carries 4 attributes allowing to designate
4627
      the device as can be found with the <code>lspci</code> or
4628
      with <code>virsh nodedev-list</code>. For SCSI devices a 'drive'
4629 4630 4631 4632
      address type must be used. For mediated devices, which are software-only
      devices defining an allocation of resources on the physical parent device,
      the address type used must conform to the <code>model</code> attribute
      of element <code>hostdev</code>, e.g. any address type other than PCI for
4633 4634
      <code>vfio-pci</code> device API or any address type other than CCW for
      <code>vfio-ccw</code> device API will result in an error.
4635 4636
      <a href="#elementsAddress">See above</a> for more details on the address
      element.</dd>
4637 4638 4639 4640 4641 4642 4643
      <dt><code>driver</code></dt>
      <dd>
        PCI devices can have an optional <code>driver</code>
        subelement that specifies which backend driver to use for PCI
        device assignment. Use the <code>name</code> attribute to
        select either "vfio" (for the new VFIO device assignment
        backend, which is compatible with UEFI SecureBoot) or "kvm"
4644
        (the legacy device assignment handled directly by the KVM
4645
        kernel module)<span class="since">Since 1.0.5 (QEMU and KVM
4646 4647 4648 4649 4650 4651 4652 4653
        only, requires kernel 3.6 or newer)</span>. When specified,
        device assignment will fail if the requested method of device
        assignment isn't available on the host. When not specified,
        the default is "vfio" on systems where the VFIO driver is
        available and loaded, and "kvm" on older systems, or those
        where the VFIO driver hasn't been
        loaded <span class="since">Since 1.1.3</span> (prior to that
        the default was always "kvm").
4654
      </dd>
O
Osier Yang 已提交
4655 4656 4657 4658
      <dt><code>readonly</code></dt>
      <dd>Indicates that the device is readonly, only supported by SCSI host
        device now. <span class="since">Since 1.0.6 (QEMU and KVM only)</span>
      </dd>
4659 4660 4661 4662 4663
      <dt><code>shareable</code></dt>
      <dd>If present, this indicates the device is expected to be shared
        between domains (assuming the hypervisor and OS support this).
        Only supported by SCSI host device.
        <span class="since">Since 1.0.6</span>
4664 4665 4666 4667 4668
        <p>
          Note: Although <code>shareable</code> was introduced
          <span class="since">in 1.0.6</span>, it did not work as
          as expected until <span class="since">1.2.2</span>.
        </p>
4669
      </dd>
4670 4671
    </dl>

4672

4673
    <h5><a id="elementsHostDevCaps">Block / character devices</a></h5>
4674 4675 4676 4677

    <p>
      Block / character devices from the host can be passed through
      to the guest using the <code>hostdev</code> element. This is
4678 4679
      only possible with container based virtualization. Devices are specified
      by a fully qualified path.
4680 4681 4682 4683 4684 4685 4686 4687 4688 4689 4690 4691 4692 4693 4694 4695 4696 4697 4698 4699
      <span class="since">since after 1.0.1 for LXC</span>:
    </p>

    <pre>
...
&lt;hostdev mode='capabilities' type='storage'&gt;
  &lt;source&gt;
    &lt;block&gt;/dev/sdf1&lt;/block&gt;
  &lt;/source&gt;
&lt;/hostdev&gt;
...
    </pre>

    <pre>
...
&lt;hostdev mode='capabilities' type='misc'&gt;
  &lt;source&gt;
    &lt;char&gt;/dev/input/event3&lt;/char&gt;
  &lt;/source&gt;
&lt;/hostdev&gt;
4700 4701 4702
...
    </pre>

O
Osier Yang 已提交
4703
    <pre>
4704 4705 4706 4707 4708 4709
...
&lt;hostdev mode='capabilities' type='net'&gt;
  &lt;source&gt;
    &lt;interface&gt;eth0&lt;/interface&gt;
  &lt;/source&gt;
&lt;/hostdev&gt;
4710 4711 4712 4713 4714 4715 4716
...
    </pre>

    <dl>
      <dt><code>hostdev</code></dt>
      <dd>The <code>hostdev</code> element is the main container for describing
        host devices. For block/character device passthrough <code>mode</code> is
4717 4718
        always "capabilities" and <code>type</code> is "storage" for a block
        device, "misc" for a character device and "net" for a host network
4719
        interface.
4720 4721 4722 4723 4724
      </dd>
      <dt><code>source</code></dt>
      <dd>The source element describes the device as seen from the host.
        For block devices, the path to the block device in the host
        OS is provided in the nested "block" element, while for character
4725 4726
        devices the "char" element is used. For network interfaces, the
        name of the interface is provided in the "interface" element.
4727 4728 4729
      </dd>
    </dl>

4730
    <h4><a id="elementsRedir">Redirected devices</a></h4>
4731 4732 4733 4734 4735 4736 4737 4738

    <p>
      USB device redirection through a character device is
      supported <span class="since">since after 0.9.5 (KVM
      only)</span>:
    </p>

<pre>
4739 4740 4741 4742 4743 4744 4745 4746 4747 4748 4749 4750
...
&lt;devices&gt;
  &lt;redirdev bus='usb' type='tcp'&gt;
    &lt;source mode='connect' host='localhost' service='4000'/&gt;
    &lt;boot order='1'/&gt;
  &lt;/redirdev&gt;
  &lt;redirfilter&gt;
    &lt;usbdev class='0x08' vendor='0x1234' product='0xbeef' version='2.56' allow='yes'/&gt;
    &lt;usbdev allow='no'/&gt;
  &lt;/redirfilter&gt;
&lt;/devices&gt;
...</pre>
4751 4752 4753 4754 4755 4756 4757 4758 4759 4760 4761 4762 4763 4764

    <dl>
      <dt><code>redirdev</code></dt>
      <dd>The <code>redirdev</code> element is the main container for
        describing redirected devices. <code>bus</code> must be "usb"
        for a USB device.

        An additional attribute <code>type</code> is required,
        matching one of the
        supported <a href="#elementsConsole">serial device</a> types,
        to describe the host side of the
        tunnel; <code>type='tcp'</code>
        or <code>type='spicevmc'</code> (which uses the usbredir
        channel of a <a href="#elementsGraphics">SPICE graphics
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        device</a>) are typical. The redirdev element has an optional
        sub-element <code>&lt;address&gt;</code> which can tie the
4767 4768 4769 4770
        device to a particular controller. Further sub-elements,
        such as <code>&lt;source&gt;</code>, may be required according
        to the given type, although a <code>&lt;target&gt;</code> sub-element
        is not required (since the consumer of the character device is
4771 4772 4773 4774 4775 4776 4777 4778 4779 4780
        the hypervisor itself, rather than a device visible in the guest).
      </dd>
      <dt><code>boot</code></dt>

      <dd>Specifies that the device is bootable.
        The <code>order</code> attribute determines the order in which
        devices will be tried during boot sequence. The per-device
        <code>boot</code> elements cannot be used together with general
        boot elements in  <a href="#elementsOSBIOS">BIOS bootloader</a> section.
        (<span class="since">Since 1.0.1</span>)
4781 4782 4783 4784
      </dd>
      <dt><code>redirfilter</code></dt>
      <dd>The<code> redirfilter </code>element is used for creating the
        filter rule to filter out certain devices from redirection.
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        It uses sub-element <code>&lt;usbdev&gt;</code> to define each filter rule.
        <code>class</code> attribute is the USB Class code, for example,
4787
        0x08 represents mass storage devices. The USB device can be addressed by
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        vendor / product id using the <code>vendor</code> and <code>product</code> attributes.
4789 4790
        <code>version</code> is the device revision from the bcdDevice field (not
        the version of the USB protocol).
4791
        These four attributes are optional and <code>-1</code> can be used to allow
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        any value for them. <code>allow</code> attribute is mandatory,
4793 4794
        'yes' means allow, 'no' for deny.
      </dd>
4795 4796
    </dl>

4797
    <h4><a id="elementsSmartcard">Smartcard devices</a></h4>
4798 4799 4800 4801 4802 4803 4804 4805 4806 4807 4808 4809 4810 4811 4812

    <p>
      A virtual smartcard device can be supplied to the guest via the
      <code>smartcard</code> element. A USB smartcard reader device on
      the host cannot be used on a guest with simple device
      passthrough, since it will then not be available on the host,
      possibly locking the host computer when it is "removed".
      Therefore, some hypervisors provide a specialized virtual device
      that can present a smartcard interface to the guest, with
      several modes for describing how credentials are obtained from
      the host or even a from a channel created to a third-party
      smartcard provider. <span class="since">Since 0.8.8</span>
    </p>

<pre>
4813 4814 4815 4816 4817 4818 4819 4820 4821 4822 4823 4824 4825 4826 4827 4828 4829
...
&lt;devices&gt;
  &lt;smartcard mode='host'/&gt;
  &lt;smartcard mode='host-certificates'&gt;
    &lt;certificate&gt;cert1&lt;/certificate&gt;
    &lt;certificate&gt;cert2&lt;/certificate&gt;
    &lt;certificate&gt;cert3&lt;/certificate&gt;
    &lt;database&gt;/etc/pki/nssdb/&lt;/database&gt;
  &lt;/smartcard&gt;
  &lt;smartcard mode='passthrough' type='tcp'&gt;
    &lt;source mode='bind' host='127.0.0.1' service='2001'/&gt;
    &lt;protocol type='raw'/&gt;
    &lt;address type='ccid' controller='0' slot='0'/&gt;
  &lt;/smartcard&gt;
  &lt;smartcard mode='passthrough' type='spicevmc'/&gt;
&lt;/devices&gt;
...
4830 4831 4832 4833 4834 4835 4836 4837 4838 4839 4840
</pre>

    <p>
      The <code>&lt;smartcard&gt;</code> element has a mandatory
      attribute <code>mode</code>.  The following modes are supported;
      in each mode, the guest sees a device on its USB bus that
      behaves like a physical USB CCID (Chip/Smart Card Interface
      Device) card.
    </p>

    <dl>
4841
      <dt><code>host</code></dt>
4842 4843 4844 4845 4846 4847
      <dd>The simplest operation, where the hypervisor relays all
      requests from the guest into direct access to the host's
      smartcard via NSS.  No other attributes or sub-elements are
      required.  See below about the use of an
      optional <code>&lt;address&gt;</code> sub-element.</dd>

4848
      <dt><code>host-certificates</code></dt>
4849 4850 4851 4852 4853 4854 4855 4856 4857 4858 4859 4860 4861
      <dd>Rather than requiring a smartcard to be plugged into the
      host, it is possible to provide three NSS certificate names
      residing in a database on the host.  These certificates can be
      generated via the command <code>certutil -d /etc/pki/nssdb -x -t
      CT,CT,CT -S -s CN=cert1 -n cert1</code>, and the resulting three
      certificate names must be supplied as the content of each of
      three <code>&lt;certificate&gt;</code> sub-elements.  An
      additional sub-element <code>&lt;database&gt;</code> can specify
      the absolute path to an alternate directory (matching
      the <code>-d</code> option of the <code>certutil</code> command
      when creating the certificates); if not present, it defaults to
      /etc/pki/nssdb.</dd>

4862
      <dt><code>passthrough</code></dt>
4863 4864 4865 4866 4867 4868 4869
      <dd>Rather than having the hypervisor directly communicate with
      the host, it is possible to tunnel all requests through a
      secondary character device to a third-party provider (which may
      in turn be talking to a smartcard or using three certificate
      files).  In this mode of operation, an additional
      attribute <code>type</code> is required, matching one of the
      supported <a href="#elementsConsole">serial device</a> types, to
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      describe the host side of the tunnel; <code>type='tcp'</code>
      or <code>type='spicevmc'</code> (which uses the smartcard
      channel of a <a href="#elementsGraphics">SPICE graphics
      device</a>) are typical.  Further sub-elements, such
      as <code>&lt;source&gt;</code>, may be required according to the
4875 4876 4877 4878 4879 4880 4881 4882 4883
      given type, although a <code>&lt;target&gt;</code> sub-element
      is not required (since the consumer of the character device is
      the hypervisor itself, rather than a device visible in the
      guest).</dd>
    </dl>

    <p>
      Each mode supports an optional
      sub-element <code>&lt;address&gt;</code>, which fine-tunes the
4884 4885 4886
      correlation between the smartcard and a ccid bus
      controller, <a href="#elementsAddress">documented above</a>.
      For now, qemu only supports at most one
4887 4888 4889
      smartcard, with an address of bus=0 slot=0.
    </p>

4890
    <h4><a id="elementsNICS">Network interfaces</a></h4>
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4892
<pre>
4893 4894 4895 4896 4897 4898 4899 4900 4901 4902
...
&lt;devices&gt;
  &lt;interface type='direct' trustGuestRxFilters='yes'&gt;
    &lt;source dev='eth0'/&gt;
    &lt;mac address='52:54:00:5d:c7:9e'/&gt;
    &lt;boot order='1'/&gt;
    &lt;rom bar='off'/&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
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    <p>
      There are several possibilities for specifying a network
      interface visible to the guest.  Each subsection below provides
4907 4908 4909 4910 4911 4912 4913 4914 4915 4916 4917 4918
      more details about common setup options.
    </p>
    <p>
      <span class="since">Since 1.2.10</span>),
      the <code>interface</code> element
      property <code>trustGuestRxFilters</code> provides the
      capability for the host to detect and trust reports from the
      guest regarding changes to the interface mac address and receive
      filters by setting the attribute to <code>yes</code>. The default
      setting for the attribute is <code>no</code> for security
      reasons and support depends on the guest network device model as
      well as the type of connection on the host - currently it is
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      only supported for the virtio device model and for macvtap
4920 4921 4922 4923
      connections on the host.
    </p>
    <p>
      Each <code>&lt;interface&gt;</code> element has an
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      optional <code>&lt;address&gt;</code> sub-element that can tie
      the interface to a particular pci slot, with
4926 4927
      attribute <code>type='pci'</code>
      as <a href="#elementsAddress">documented above</a>.
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    </p>

4930
    <h5><a id="elementsNICSVirtual">Virtual network</a></h5>
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    <p>
      <strong><em>
      This is the recommended config for general guest connectivity on
4935 4936 4937 4938
      hosts with dynamic / wireless networking configs (or multi-host
      environments where the host hardware details are described
      separately in a <code>&lt;network&gt;</code>
      definition <span class="since">Since 0.9.4</span>).
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      </em></strong>
    </p>

    <p>
4943 4944 4945 4946 4947 4948 4949 4950 4951 4952 4953 4954 4955 4956 4957 4958 4959 4960 4961 4962 4963 4964 4965 4966 4967 4968 4969

      Provides a connection whose details are described by the named
      network definition. Depending on the virtual network's "forward
      mode" configuration, the network may be totally isolated
      (no <code>&lt;forward&gt;</code> element given), NAT'ing to an
      explicit network device or to the default route
      (<code>&lt;forward mode='nat'&gt;</code>), routed with no NAT
      (<code>&lt;forward mode='route'/&gt;</code>), or connected
      directly to one of the host's network interfaces (via macvtap)
      or bridge devices ((<code>&lt;forward
      mode='bridge|private|vepa|passthrough'/&gt;</code> <span class="since">Since
      0.9.4</span>)
    </p>
    <p>
      For networks with a forward mode of bridge, private, vepa, and
      passthrough, it is assumed that the host has any necessary DNS
      and DHCP services already setup outside the scope of libvirt. In
      the case of isolated, nat, and routed networks, DHCP and DNS are
      provided on the virtual network by libvirt, and the IP range can
      be determined by examining the virtual network config with
      '<code>virsh net-dumpxml [networkname]</code>'. There is one
      virtual network called 'default' setup out of the box which does
      NAT'ing to the default route and has an IP range
      of <code>192.168.122.0/255.255.255.0</code>. Each guest will
      have an associated tun device created with a name of vnetN,
      which can also be overridden with the &lt;target&gt; element
      (see
4970
      <a href="#elementsNICSTargetOverride">overriding the target element</a>).
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    </p>
4972 4973 4974 4975 4976 4977
    <p>
      When the source of an interface is a network,
      a <code>portgroup</code> can be specified along with the name of
      the network; one network may have multiple portgroups defined,
      with each portgroup containing slightly different configuration
      information for different classes of network
4978 4979 4980 4981 4982 4983 4984 4985 4986 4987 4988 4989 4990 4991 4992 4993 4994 4995 4996
      connections. <span class="since">Since 0.9.4</span>.
    </p>
    <p>
      Also, similar to <code>direct</code> network connections
      (described below), a connection of type <code>network</code> may
      specify a <code>virtualport</code> element, with configuration
      data to be forwarded to a vepa (802.1Qbg) or 802.1Qbh compliant
      switch (<span class="since">Since 0.8.2</span>), or to an
      Open vSwitch virtual switch (<span class="since">Since
      0.9.11</span>).
    </p>
    <p>
      Since the actual type of switch may vary depending on the
      configuration in the <code>&lt;network&gt;</code> on the host,
      it is acceptable to omit the virtualport <code>type</code>
      attribute, and specify attributes from multiple different
      virtualport types (and also to leave out certain attributes); at
      domain startup time, a complete <code>&lt;virtualport&gt;</code>
      element will be constructed by merging together the type and
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      attributes defined in the network and the portgroup referenced
      by the interface. The newly-constructed virtualport is a combination
      of them. The attributes from lower virtualport can't make change
      on the ones defined in higher virtualport.
      Interface takes the highest priority, portgroup is lowest priority.
5002 5003 5004
      (<span class="since">Since 0.10.0</span>). For example, in order
      to work properly with both an 802.1Qbh switch and an Open vSwitch
      switch, you may choose to specify no type, but both
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      a <code>profileid</code> (in case the switch is 802.1Qbh) and
5006 5007 5008 5009 5010 5011 5012 5013 5014
      an <code>interfaceid</code> (in case the switch is Open vSwitch)
      (you may also omit the other attributes, such as managerid,
      typeid, or profileid, to be filled in from the
      network's <code>&lt;virtualport&gt;</code>). If you want to
      limit a guest to connecting only to certain types of switches,
      you can specify the virtualport type, but still omit some/all of
      the parameters - in this case if the host's network has a
      different type of virtualport, connection of the interface will
      fail.
5015
    </p>
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5017
<pre>
5018 5019 5020 5021 5022
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
  &lt;/interface&gt;
5023
  ...
5024 5025 5026 5027 5028 5029 5030 5031 5032 5033 5034
  &lt;interface type='network'&gt;
    &lt;source network='default' portgroup='engineering'/&gt;
    &lt;target dev='vnet7'/&gt;
    &lt;mac address="00:11:22:33:44:55"/&gt;
    &lt;virtualport&gt;
      &lt;parameters instanceid='09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f'/&gt;
    &lt;/virtualport&gt;

  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
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5036
    <h5><a id="elementsNICSBridge">Bridge to LAN</a></h5>
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    <p>
      <strong><em>
      This is the recommended config for general guest connectivity on
5041
      hosts with static wired networking configs.
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      </em></strong>
    </p>

    <p>
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      Provides a bridge from the VM directly to the LAN. This assumes
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      there is a bridge device on the host which has one or more of the hosts
      physical NICs enslaved. The guest VM will have an associated tun device
      created with a name of vnetN, which can also be overridden with the
5050 5051 5052 5053 5054
      &lt;target&gt; element (see
      <a href="#elementsNICSTargetOverride">overriding the target element</a>).
      The tun device will be enslaved to the bridge. The IP range / network
      configuration is whatever is used on the LAN. This provides the guest VM
      full incoming &amp; outgoing net access just like a physical machine.
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    </p>
5056 5057 5058
    <p>
      On Linux systems, the bridge device is normally a standard Linux
      host bridge. On hosts that support Open vSwitch, it is also
5059
      possible to connect to an Open vSwitch bridge device by adding
5060 5061 5062 5063 5064 5065
      a <code>&lt;virtualport type='openvswitch'/&gt;</code> to the
      interface definition.  (<span class="since">Since
      0.9.11</span>). The Open vSwitch type virtualport accepts two
      parameters in its <code>&lt;parameters&gt;</code> element -
      an <code>interfaceid</code> which is a standard uuid used to
      uniquely identify this particular interface to Open vSwitch (if
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      you do not specify one, a random interfaceid will be generated
5067 5068 5069 5070
      for you when you first define the interface), and an
      optional <code>profileid</code> which is sent to Open vSwitch as
      the interfaces "port-profile".
    </p>
5071
<pre>
5072 5073
...
&lt;devices&gt;
5074
  ...
5075 5076 5077 5078 5079 5080 5081 5082 5083 5084 5085 5086 5087 5088 5089 5090 5091
  &lt;interface type='bridge'&gt;
    &lt;source bridge='br0'/&gt;
  &lt;/interface&gt;
  &lt;interface type='bridge'&gt;
    &lt;source bridge='br1'/&gt;
    &lt;target dev='vnet7'/&gt;
    &lt;mac address="00:11:22:33:44:55"/&gt;
  &lt;/interface&gt;
  &lt;interface type='bridge'&gt;
    &lt;source bridge='ovsbr'/&gt;
    &lt;virtualport type='openvswitch'&gt;
      &lt;parameters profileid='menial' interfaceid='09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f'/&gt;
    &lt;/virtualport&gt;
  &lt;/interface&gt;
  ...
&lt;/devices&gt;
...</pre>
5092 5093 5094 5095 5096 5097 5098 5099 5100 5101 5102 5103 5104 5105

    <p>
      On hosts that support Open vSwitch on the kernel side and have the
      Midonet Host Agent configured, it is also possible to connect to the
      'midonet' bridge device by adding a
      <code>&lt;virtualport type='midonet'/&gt;</code> to the
      interface definition.  (<span class="since">Since
      1.2.13</span>). The Midonet virtualport type requires an
      <code>interfaceid</code> attribute in its
      <code>&lt;parameters&gt;</code> element. This interface id is the UUID
      that specifies which port in the virtual network topology will be bound
      to the interface.
    </p>
<pre>
5106 5107
...
&lt;devices&gt;
5108
  ...
5109 5110 5111 5112 5113 5114 5115 5116 5117 5118 5119 5120 5121 5122 5123 5124 5125
  &lt;interface type='bridge'&gt;
    &lt;source bridge='br0'/&gt;
  &lt;/interface&gt;
  &lt;interface type='bridge'&gt;
    &lt;source bridge='br1'/&gt;
    &lt;target dev='vnet7'/&gt;
    &lt;mac address="00:11:22:33:44:55"/&gt;
  &lt;/interface&gt;
  &lt;interface type='bridge'&gt;
    &lt;source bridge='midonet'/&gt;
    &lt;virtualport type='midonet'&gt;
      &lt;parameters interfaceid='0b2d64da-3d0e-431e-afdd-804415d6ebbb'/&gt;
    &lt;/virtualport&gt;
  &lt;/interface&gt;
  ...
&lt;/devices&gt;
...</pre>
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5127
    <h5><a id="elementsNICSSlirp">Userspace SLIRP stack</a></h5>
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    <p>
      Provides a virtual LAN with NAT to the outside world. The virtual
      network has DHCP &amp; DNS services and will give the guest VM addresses
      starting from <code>10.0.2.15</code>. The default router will be
      <code>10.0.2.2</code> and the DNS server will be <code>10.0.2.3</code>.
      This networking is the only option for unprivileged users who need their
5135 5136 5137 5138 5139 5140 5141 5142 5143
      VMs to have outgoing access. <span class="since">Since 3.8.0</span>
      it is possible to override the default network address by
      including an <code>ip</code> element specifying an IPv4
      address in its one mandatory attribute, <code>address</code>.
      Optionally, a second <code>ip</code> element with a
      <code>family</code> attribute set to "ipv6" can be
      specified to add an IPv6 address to the interface.
      <code>address</code>. Optionally, address
      <code>prefix</code> can be specified.
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    </p>

5146
<pre>
5147 5148 5149
...
&lt;devices&gt;
  &lt;interface type='user'/&gt;
5150
  ...
5151 5152
  &lt;interface type='user'&gt;
    &lt;mac address="00:11:22:33:44:55"/&gt;
5153 5154
    &lt;ip family='ipv4' address='172.17.2.0' prefix='24'/&gt;
    &lt;ip family='ipv6' address='2001:db8:ac10:fd01::' prefix='64'/&gt;
5155 5156 5157
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
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5158 5159


5160
    <h5><a id="elementsNICSEthernet">Generic ethernet connection</a></h5>
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    <p>
      Provides a means for the administrator to execute an arbitrary script
      to connect the guest's network to the LAN. The guest will have a tun
      device created with a name of vnetN, which can also be overridden with the
      &lt;target&gt; element. After creating the tun device a shell script will
      be run which is expected to do whatever host network integration is
      required. By default this script is called /etc/qemu-ifup but can be
      overridden.
    </p>

5172
<pre>
5173 5174 5175
...
&lt;devices&gt;
  &lt;interface type='ethernet'/&gt;
5176
  ...
5177 5178 5179 5180 5181 5182
  &lt;interface type='ethernet'&gt;
    &lt;target dev='vnet7'/&gt;
    &lt;script path='/etc/qemu-ifup-mynet'/&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
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5184
    <h5><a id="elementsNICSDirect">Direct attachment to physical interface</a></h5>
5185 5186 5187

    <p>
      Provides direct attachment of the virtual machine's NIC to the given
5188
      physical interface of the host.
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      <span class="since">Since 0.7.7 (QEMU and KVM only)</span><br/>
5190 5191 5192
      This setup requires the Linux macvtap
      driver to be available. <span class="since">(Since Linux 2.6.34.)</span>
      One of the modes 'vepa'
5193
      ( <a href="http://www.ieee802.org/1/files/public/docs2009/new-evb-congdon-vepa-modular-0709-v01.pdf">
5194
      'Virtual Ethernet Port Aggregator'</a>), 'bridge' or 'private'
5195
      can be chosen for the operation mode of the macvtap device, 'vepa'
5196 5197
      being the default mode. The individual modes cause the delivery of
      packets to behave as follows:
5198
    </p>
5199 5200 5201 5202 5203 5204 5205 5206 5207 5208 5209 5210
    <p>
      If the model type is set to <code>virtio</code> and
      interface's <code>trustGuestRxFilters</code> attribute is set
      to <code>yes</code>, changes made to the interface mac address,
      unicast/multicast receive filters, and vlan settings in the
      guest will be monitored and propagated to the associated macvtap
      device on the host (<span class="since">Since
      1.2.10</span>). If <code>trustGuestRxFilters</code> is not set,
      or is not supported for the device model in use, an attempted
      change to the mac address originating from the guest side will
      result in a non-working network connection.
    </p>
5211

5212 5213 5214 5215 5216 5217 5218 5219 5220 5221 5222
    <dl>
      <dt><code>vepa</code></dt>
      <dd>All VMs' packets are sent to the external bridge. Packets
      whose destination is a VM on the same host as where the
      packet originates from are sent back to the host by the VEPA
      capable bridge (today's bridges are typically not VEPA capable).</dd>
      <dt><code>bridge</code></dt>
      <dd>Packets whose destination is on the same host as where they
      originate from are directly delivered to the target macvtap device.
      Both origin and destination devices need to be in bridge mode
      for direct delivery. If either one of them is in <code>vepa</code> mode,
E
Eric Blake 已提交
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      a VEPA capable bridge is required.</dd>
5224 5225 5226 5227 5228 5229
      <dt><code>private</code></dt>
      <dd>All packets are sent to the external bridge and will only be
      delivered to a target VM on the same host if they are sent through an
      external router or gateway and that device sends them back to the
      host. This procedure is followed if either the source or destination
      device is in <code>private</code> mode.</dd>
5230 5231 5232 5233 5234 5235 5236
      <dt><code>passthrough</code></dt>
      <dd>This feature attaches a virtual function of a SRIOV capable
      NIC directly to a VM without losing the migration capability.
      All packets are sent to the VF/IF of the configured network device.
      Depending on the capabilities of the device additional prerequisites or
      limitations may apply; for example, on Linux this requires
      kernel 2.6.38 or newer. <span class="since">Since 0.9.2</span></dd>
5237 5238
    </dl>

5239
<pre>
5240 5241
...
&lt;devices&gt;
5242
  ...
5243 5244 5245 5246 5247
  &lt;interface type='direct' trustGuestRxFilters='no'&gt;
    &lt;source dev='eth0' mode='vepa'/&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5248

5249 5250 5251 5252
    <p>
      The network access of direct attached virtual machines can be
      managed by the hardware switch to which the physical interface
      of the host machine is connected to.
E
Eric Blake 已提交
5253
    </p>
5254 5255 5256 5257 5258 5259 5260
    <p>
      The interface can have additional parameters as shown below,
      if the switch is conforming to the IEEE 802.1Qbg standard.
      The parameters of the virtualport element are documented in more detail
      in the IEEE 802.1Qbg standard. The values are network specific and
      should be provided by the network administrator. In 802.1Qbg terms,
      the Virtual Station Interface (VSI) represents the virtual interface
5261
      of a virtual machine. <span class="since">Since 0.8.2</span>
5262
    </p>
5263 5264 5265 5266
    <p>
      Please note that IEEE 802.1Qbg requires a non-zero value for the
      VLAN ID.
    </p>
5267 5268 5269 5270 5271 5272 5273 5274 5275 5276 5277 5278 5279 5280 5281 5282 5283 5284 5285 5286 5287
    <dl>
      <dt><code>managerid</code></dt>
      <dd>The VSI Manager ID identifies the database containing the VSI type
        and instance definitions. This is an integer value and the
        value 0 is reserved.</dd>
      <dt><code>typeid</code></dt>
      <dd>The VSI Type ID identifies a VSI type characterizing the network
        access. VSI types are typically managed by network administrator.
        This is an integer value.
      </dd>
      <dt><code>typeidversion</code></dt>
      <dd>The VSI Type Version allows multiple versions of a VSI Type.
        This is an integer value.
      </dd>
      <dt><code>instanceid</code></dt>
      <dd>The VSI Instance ID Identifier is generated when a VSI instance
        (i.e. a virtual interface of a virtual machine) is created.
        This is a globally unique identifier.
      </dd>
    </dl>
<pre>
5288 5289
...
&lt;devices&gt;
5290
  ...
5291 5292 5293 5294 5295 5296 5297 5298
  &lt;interface type='direct'&gt;
    &lt;source dev='eth0.2' mode='vepa'/&gt;
    &lt;virtualport type="802.1Qbg"&gt;
      &lt;parameters managerid="11" typeid="1193047" typeidversion="2" instanceid="09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f"/&gt;
    &lt;/virtualport&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5299

5300 5301 5302 5303 5304 5305 5306 5307 5308
    <p>
      The interface can have additional parameters as shown below
      if the switch is conforming to the IEEE 802.1Qbh standard.
      The values are network specific and should be provided by the
      network administrator. <span class="since">Since 0.8.2</span>
    </p>
    <dl>
      <dt><code>profileid</code></dt>
      <dd>The profile ID contains the name of the port profile that is to
E
Eric Blake 已提交
5309
        be applied to this interface.  This name is resolved by the port
5310 5311 5312 5313 5314
        profile database into the network parameters from the port profile,
        and those network parameters will be applied to this interface.
      </dd>
    </dl>
  <pre>
5315 5316
...
&lt;devices&gt;
5317
  ...
5318 5319 5320 5321 5322 5323 5324 5325 5326
  &lt;interface type='direct'&gt;
    &lt;source dev='eth0' mode='private'/&gt;
    &lt;virtualport type='802.1Qbh'&gt;
      &lt;parameters profileid='finance'/&gt;
    &lt;/virtualport&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...
</pre>
5327

5328

5329
    <h5><a id="elementsNICSHostdev">PCI Passthrough</a></h5>
5330 5331 5332 5333 5334 5335

    <p>
      A PCI network device (specified by the &lt;source&gt; element)
      is directly assigned to the guest using generic device
      passthrough, after first optionally setting the device's MAC
      address to the configured value, and associating the device with
5336
      an 802.1Qbh capable switch using an optionally specified
5337
      &lt;virtualport&gt; element (see the examples of virtualport
5338 5339 5340 5341 5342 5343 5344 5345 5346
      given above for type='direct' network devices). Note that - due
      to limitations in standard single-port PCI ethernet card driver
      design - only SR-IOV (Single Root I/O Virtualization) virtual
      function (VF) devices can be assigned in this manner; to assign
      a standard single-port PCI or PCIe ethernet card to a guest, use
      the traditional &lt;hostdev&gt; device definition and
      <span class="since">Since 0.9.11</span>
    </p>

5347 5348 5349 5350 5351 5352 5353 5354 5355 5356 5357 5358
    <p>
      To use VFIO device assignment rather than traditional/legacy KVM
      device assignment (VFIO is a new method of device assignment
      that is compatible with UEFI Secure Boot), a type='hostdev'
      interface can have an optional <code>driver</code> sub-element
      with a <code>name</code> attribute set to "vfio". To use legacy
      KVM device assignment you can set <code>name</code> to "kvm" (or
      simply omit the <code>&lt;driver&gt;</code> element, since "kvm"
      is currently the default).
      <span class="since">Since 1.0.5 (QEMU and KVM only, requires kernel 3.6 or newer)</span>
    </p>

5359 5360 5361 5362 5363 5364 5365 5366 5367 5368 5369 5370 5371 5372
    <p>
      Note that this "intelligent passthrough" of network devices is
      very similar to the functionality of a standard &lt;hostdev&gt;
      device, the difference being that this method allows specifying
      a MAC address and &lt;virtualport&gt; for the passed-through
      device. If these capabilities are not required, if you have a
      standard single-port PCI, PCIe, or USB network card that doesn't
      support SR-IOV (and hence would anyway lose the configured MAC
      address during reset after being assigned to the guest domain),
      or if you are using a version of libvirt older than 0.9.11, you
      should use standard &lt;hostdev&gt; to assign the device to the
      guest instead of &lt;interface type='hostdev'/&gt;.
    </p>

5373 5374 5375 5376 5377 5378
    <p>
      Similar to the functionality of a standard &lt;hostdev&gt; device,
      when <code>managed</code> is "yes", it is detached from the host
      before being passed on to the guest, and reattached to the host
      after the guest exits. If <code>managed</code> is omitted or "no",
      the user is responsible to call <code>virNodeDeviceDettach</code>
J
John Ferlan 已提交
5379
      (or <code>virsh nodedev-detach</code>) before starting the guest
5380 5381 5382 5383 5384
      or hot-plugging the device, and <code>virNodeDeviceReAttach</code>
      (or <code>virsh nodedev-reattach</code>) after hot-unplug or
      stopping the guest.
    </p>

5385
<pre>
5386 5387 5388 5389 5390 5391 5392 5393 5394 5395 5396 5397 5398 5399
...
&lt;devices&gt;
  &lt;interface type='hostdev' managed='yes'&gt;
    &lt;driver name='vfio'/&gt;
    &lt;source&gt;
      &lt;address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/&gt;
    &lt;/source&gt;
    &lt;mac address='52:54:00:6d:90:02'/&gt;
    &lt;virtualport type='802.1Qbh'&gt;
      &lt;parameters profileid='finance'/&gt;
    &lt;/virtualport&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5400 5401


5402
    <h5><a id="elementsNICSMulticast">Multicast tunnel</a></h5>
D
Daniel P. Berrange 已提交
5403 5404 5405 5406 5407 5408 5409 5410 5411 5412 5413 5414 5415

    <p>
      A multicast group is setup to represent a virtual network. Any VMs
      whose network devices are in the same multicast group can talk to each
      other even across hosts. This mode is also available to unprivileged
      users. There is no default DNS or DHCP support and no outgoing network
      access. To provide outgoing network access, one of the VMs should have a
      2nd NIC which is connected to one of the first 4 network types and do the
      appropriate routing. The multicast protocol is compatible with that used
      by user mode linux guests too. The source address used must be from the
      multicast address block.
    </p>

5416
<pre>
5417 5418 5419 5420 5421 5422 5423 5424
...
&lt;devices&gt;
  &lt;interface type='mcast'&gt;
    &lt;mac address='52:54:00:6d:90:01'/&gt;
    &lt;source address='230.0.0.1' port='5558'/&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
5425

5426
    <h5><a id="elementsNICSTCP">TCP tunnel</a></h5>
D
Daniel P. Berrange 已提交
5427 5428 5429 5430 5431 5432 5433 5434 5435 5436

    <p>
      A TCP client/server architecture provides a virtual network. One VM
      provides the server end of the network, all other VMS are configured as
      clients. All network traffic is routed between the VMs via the server.
      This mode is also available to unprivileged users. There is no default
      DNS or DHCP support and no outgoing network access. To provide outgoing
      network access, one of the VMs should have a 2nd NIC which is connected
      to one of the first 4 network types and do the appropriate routing.</p>

5437
<pre>
5438 5439 5440 5441 5442 5443
...
&lt;devices&gt;
  &lt;interface type='server'&gt;
    &lt;mac address='52:54:00:22:c9:42'/&gt;
    &lt;source address='192.168.0.1' port='5558'/&gt;
  &lt;/interface&gt;
5444
  ...
5445 5446 5447 5448 5449 5450
  &lt;interface type='client'&gt;
    &lt;mac address='52:54:00:8b:c9:51'/&gt;
    &lt;source address='192.168.0.1' port='5558'/&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5451

5452
    <h5><a id="elementsNICSUDP">UDP unicast tunnel</a></h5>
5453 5454 5455 5456 5457 5458 5459 5460 5461 5462 5463 5464

    <p>
    A UDP unicast architecture provides a virtual network which enables
    connections between QEMU instances using QEMU's UDP infrastructure.

    The xml "source" address is the endpoint address to which the UDP socket
    packets will be sent from the host running QEMU.
    The xml "local" address is the address of the interface from which the
    UDP socket packets will originate from the QEMU host.
    <span class="since">Since 1.2.20</span></p>

<pre>
5465 5466 5467 5468 5469 5470 5471 5472 5473 5474
...
&lt;devices&gt;
  &lt;interface type='udp'&gt;
    &lt;mac address='52:54:00:22:c9:42'/&gt;
    &lt;source address='127.0.0.1' port='11115'&gt;
      &lt;local address='127.0.0.1' port='11116'/&gt;
    &lt;/source&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
5475

5476
    <h5><a id="elementsNICSModel">Setting the NIC model</a></h5>
5477

5478
<pre>
5479 5480 5481 5482 5483 5484 5485 5486 5487
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet1'/&gt;
    <b>&lt;model type='ne2k_pci'/&gt;</b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5488 5489 5490 5491 5492 5493 5494 5495 5496 5497 5498 5499 5500 5501 5502 5503 5504 5505 5506 5507 5508 5509

    <p>
      For hypervisors which support this, you can set the model of
      emulated network interface card.
    </p>

    <p>
      The values for <code>type</code> aren't defined specifically by
      libvirt, but by what the underlying hypervisor supports (if
      any).  For QEMU and KVM you can get a list of supported models
      with these commands:
    </p>

<pre>
qemu -net nic,model=? /dev/null
qemu-kvm -net nic,model=? /dev/null
</pre>

    <p>
      Typical values for QEMU and KVM include:
      ne2k_isa i82551 i82557b i82559er ne2k_pci pcnet rtl8139 e1000 virtio
    </p>
D
Daniel P. Berrange 已提交
5510

5511
    <h5><a id="elementsDriverBackendOptions">Setting NIC driver-specific options</a></h5>
5512 5513

<pre>
5514 5515 5516 5517 5518 5519
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet1'/&gt;
    &lt;model type='virtio'/&gt;
5520
    <b>&lt;driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off' queues='5' rx_queue_size='256' tx_queue_size='256'&gt;
5521 5522 5523 5524 5525 5526 5527
      &lt;host csum='off' gso='off' tso4='off' tso6='off' ecn='off' ufo='off' mrg_rxbuf='off'/&gt;
      &lt;guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/&gt;
    &lt;/driver&gt;
    </b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5528 5529 5530 5531 5532 5533 5534 5535 5536

    <p>
      Some NICs may have tunable driver-specific options. These are
      set as attributes of the <code>driver</code> sub-element of the
      interface definition. Currently the following attributes are
      available for the <code>"virtio"</code> NIC driver:
    </p>

    <dl>
5537 5538 5539 5540 5541 5542 5543 5544 5545 5546 5547 5548
      <dt><code>name</code></dt>
      <dd>
        The optional <code>name</code> attribute forces which type of
        backend driver to use. The value can be either 'qemu' (a
        user-space backend) or 'vhost' (a kernel backend, which
        requires the vhost module to be provided by the kernel); an
        attempt to require the vhost driver without kernel support
        will be rejected.  If this attribute is not present, then the
        domain defaults to 'vhost' if present, but silently falls back
        to 'qemu' without error.
        <span class="since">Since 0.8.8 (QEMU and KVM only)</span>
      </dd>
5549 5550 5551 5552 5553 5554 5555 5556 5557 5558 5559 5560
      <dd>
        For interfaces of type='hostdev' (PCI passthrough devices)
        the <code>name</code> attribute can optionally be set to
        "vfio" or "kvm". "vfio" tells libvirt to use VFIO device
        assignment rather than traditional KVM device assignment (VFIO
        is a new method of device assignment that is compatible with
        UEFI Secure Boot), and "kvm" tells libvirt to use the legacy
        device assignment performed directly by the kvm kernel module
        (the default is currently "kvm", but is subject to change).
        <span class="since">Since 1.0.5 (QEMU and KVM only, requires
        kernel 3.6 or newer)</span>
      </dd>
5561 5562 5563 5564 5565
      <dd>
        For interfaces of type='vhostuser', the <code>name</code>
        attribute is ignored. The backend driver used is always
        vhost-user.
      </dd>
5566

5567 5568 5569 5570 5571
      <dt><code>txmode</code></dt>
      <dd>
        The <code>txmode</code> attribute specifies how to handle
        transmission of packets when the transmit buffer is full. The
        value can be either 'iothread' or 'timer'.
E
Eric Blake 已提交
5572
        <span class="since">Since 0.8.8 (QEMU and KVM only)</span><br/><br/>
5573 5574 5575 5576

        If set to 'iothread', packet tx is all done in an iothread in
        the bottom half of the driver (this option translates into
        adding "tx=bh" to the qemu commandline -device virtio-net-pci
E
Eric Blake 已提交
5577
        option).<br/><br/>
5578 5579 5580 5581

        If set to 'timer', tx work is done in qemu, and if there is
        more tx data than can be sent at the present time, a timer is
        set before qemu moves on to do other things; when the timer
E
Eric Blake 已提交
5582
        fires, another attempt is made to send more data.<br/><br/>
5583 5584 5585 5586 5587

        The resulting difference, according to the qemu developer who
        added the option is: "bh makes tx more asynchronous and reduces
        latency, but potentially causes more processor bandwidth
        contention since the cpu doing the tx isn't necessarily the
E
Eric Blake 已提交
5588
        cpu where the guest generated the packets."<br/><br/>
5589

5590 5591 5592 5593 5594 5595 5596 5597 5598 5599 5600 5601 5602 5603 5604 5605
        <b>In general you should leave this option alone, unless you
        are very certain you know what you are doing.</b>
      </dd>
      <dt><code>ioeventfd</code></dt>
      <dd>
        This optional attribute allows users to set
        <a href='https://patchwork.kernel.org/patch/43390/'>
        domain I/O asynchronous handling</a> for interface device.
        The default is left to the discretion of the hypervisor.
        Accepted values are "on" and "off". Enabling this allows
        qemu to execute VM while a separate thread handles I/O.
        Typically guests experiencing high system CPU utilization
        during I/O will benefit from this. On the other hand,
        on overloaded host it could increase guest I/O latency.
        <span class="since">Since 0.9.3 (QEMU and KVM only)</span><br/><br/>

5606
        <b>In general you should leave this option alone, unless you
5607 5608 5609 5610 5611 5612
        are very certain you know what you are doing.</b>
      </dd>
      <dt><code>event_idx</code></dt>
      <dd>
        The <code>event_idx</code> attribute controls some aspects of
        device event processing. The value can be either 'on' or 'off'
5613
        - if it is on, it will reduce the number of interrupts and
5614 5615 5616 5617 5618 5619 5620
        exits for the guest. The default is determined by QEMU;
        usually if the feature is supported, default is on. In case
        there is a situation where this behavior is suboptimal, this
        attribute provides a way to force the feature off.
        <span class="since">Since 0.9.5 (QEMU and KVM only)</span><br/><br/>

        <b>In general you should leave this option alone, unless you
5621 5622
        are very certain you know what you are doing.</b>
      </dd>
5623 5624
      <dt><code>queues</code></dt>
      <dd>
5625 5626
        The optional <code>queues</code> attribute controls the number
        of queues to be used for either
5627
        <a href="https://www.linux-kvm.org/page/Multiqueue"> Multiqueue
5628 5629 5630 5631
        virtio-net</a> or <a href="#elementVhostuser">vhost-user</a> network
        interfaces.  Use of multiple packet processing queues requires the
        interface having the <code>&lt;model type='virtio'/&gt;</code>
        element.  Each queue will potentially be handled by a different
5632
        processor, resulting in much higher throughput.
5633
        <span class="since">virtio-net since 1.0.6 (QEMU and KVM only)</span>
5634
        <span class="since">vhost-user since 1.2.17 (QEMU and KVM only)</span>
5635
      </dd>
5636 5637 5638 5639 5640 5641 5642 5643 5644
      <dt><code>rx_queue_size</code></dt>
      <dd>
        The optional <code>rx_queue_size</code> attribute controls
        the size of virtio ring for each queue as described above.
        The default value is hypervisor dependent and may change
        across its releases. Moreover, some hypervisors may pose
        some restrictions on actual value. For instance, latest
        QEMU (as of 2016-09-01) requires value to be a power of two
        from [256, 1024] range.
5645
        <span class="since">Since 2.3.0 (QEMU and KVM only)</span><br/><br/>
5646 5647 5648 5649

        <b>In general you should leave this option alone, unless you
        are very certain you know what you are doing.</b>
      </dd>
5650 5651 5652 5653 5654 5655 5656
      <dt><code>tx_queue_size</code></dt>
      <dd>
        The optional <code>tx_queue_size</code> attribute controls
        the size of virtio ring for each queue as described above.
        The default value is hypervisor dependent and may change
        across its releases. Moreover, some hypervisors may pose
        some restrictions on actual value. For instance, QEMU
5657 5658 5659 5660
        v2.9  requires value to be a power of two from [256, 1024]
        range. In addition to that, this may work only for a subset of
        interface types, e.g. aforementioned QEMU enables this option
        only for <code>vhostuser</code> type.
5661
        <span class="since">Since 3.7.0 (QEMU and KVM only)</span><br/><br/>
5662 5663 5664 5665

        <b>In general you should leave this option alone, unless you
        are very certain you know what you are doing.</b>
      </dd>
5666 5667 5668 5669 5670 5671
      <dt>virtio options</dt>
      <dd>
        For virtio interfaces,
        <a href="#elementsVirtio">Virtio-specific options</a> can also be
        set. (<span class="since">Since 3.5.0</span>)
      </dd>
5672 5673 5674 5675 5676 5677 5678
    </dl>
    <p>
      Offloading options for the host and guest can be configured using
      the following sub-elements:
    </p>
    <dl>
      <dt><code>host</code></dt>
5679 5680 5681 5682 5683 5684 5685
      <dd>
        The <code>csum</code>, <code>gso</code>, <code>tso4</code>,
        <code>tso6</code>, <code>ecn</code> and <code>ufo</code>
        attributes with possible values <code>on</code>
        and <code>off</code> can be used to turn off host offloading options.
        By default, the supported offloads are enabled by QEMU.
        <span class="since">Since 1.2.9 (QEMU only)</span>
5686 5687 5688 5689
        The <code>mrg_rxbuf</code> attribute can be used to control
        mergeable rx buffers on the host side. Possible values are
        <code>on</code> (default) and <code>off</code>.
        <span class="since">Since 1.2.13 (QEMU only)</span>
5690
      </dd>
5691
      <dt><code>guest</code></dt>
5692 5693 5694 5695 5696 5697 5698 5699
      <dd>
        The <code>csum</code>, <code>tso4</code>,
        <code>tso6</code>, <code>ecn</code> and <code>ufo</code>
        attributes with possible values <code>on</code>
        and <code>off</code> can be used to turn off guest offloading options.
        By default, the supported offloads are enabled by QEMU.
        <span class="since">Since 1.2.9 (QEMU only)</span>
      </dd>
5700 5701
    </dl>

5702
    <h5><a id="elementsBackendOptions">Setting network backend-specific options</a></h5>
5703 5704

<pre>
5705 5706 5707 5708 5709 5710 5711 5712
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet1'/&gt;
    &lt;model type='virtio'/&gt;
    <b>&lt;backend tap='/dev/net/tun' vhost='/dev/vhost-net'/&gt;</b>
    &lt;driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off' queues='5'/&gt;
M
Michal Privoznik 已提交
5713 5714 5715
    <b>&lt;tune&gt;
      &lt;sndbuf&gt;1600&lt;/sndbuf&gt;
    &lt;/tune&gt;</b>
5716 5717 5718
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5719 5720 5721

    <p>
      For tuning the backend of the network, the <code>backend</code> element
5722 5723
      can be used. The <code>vhost</code> attribute can override the default vhost
      device path (<code>/dev/vhost-net</code>) for devices with <code>virtio</code> model.
5724 5725
      The <code>tap</code> attribute overrides the tun/tap device path (default:
      <code>/dev/net/tun</code>) for network and bridge interfaces. This does not work
M
Michal Privoznik 已提交
5726 5727 5728 5729 5730 5731
      in session mode. <span class="since">Since 1.2.9</span>
    </p>
    <p>
      For tap devices there is also <code>sndbuf</code> element which can
      adjust the size of send buffer in the host. <span class="since">Since
      0.8.8</span>
5732
    </p>
5733
    <h5><a id="elementsNICSTargetOverride">Overriding the target element</a></h5>
5734

5735
<pre>
5736 5737 5738 5739 5740 5741 5742 5743
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    <b>&lt;target dev='vnet1'/&gt;</b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5744 5745

    <p>
E
Eric Blake 已提交
5746 5747
      If no target is specified, certain hypervisors will
      automatically generate a name for the created tun device. This
5748
      name can be manually specified, however the name <i>should not
5749 5750 5751
      start with either 'vnet', 'vif', 'macvtap', or 'macvlan'</i>,
      which are prefixes reserved by libvirt and certain hypervisors.
      Manually specified targets using these prefixes may be ignored.
5752 5753
    </p>

5754 5755 5756 5757 5758 5759 5760 5761
    <p>
      Note that for LXC containers, this defines the name of the interface
      on the host side. <span class="since">Since 1.2.7</span>, to define
      the name of the device on the guest side, the <code>guest</code>
      element should be used, as in the following snippet:
    </p>

<pre>
5762 5763 5764 5765 5766 5767 5768 5769
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    <b>&lt;guest dev='myeth'/&gt;</b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5770

5771
    <h5><a id="elementsNICSBoot">Specifying boot order</a></h5>
5772 5773

<pre>
5774 5775 5776 5777 5778 5779 5780 5781 5782
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet1'/&gt;
    <b>&lt;boot order='1'/&gt;</b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5783 5784

    <p>
5785
      For hypervisors which support this, you can set a specific NIC to
5786 5787 5788 5789 5790 5791 5792 5793
      be used for network boot. The <code>order</code> attribute determines
      the order in which devices will be tried during boot sequence. The
      per-device <code>boot</code> elements cannot be used together with
      general boot elements in
      <a href="#elementsOSBIOS">BIOS bootloader</a> section.
      <span class="since">Since 0.8.8</span>
    </p>

5794
    <h5><a id="elementsNICSROM">Interface ROM BIOS configuration</a></h5>
5795 5796

<pre>
5797 5798 5799 5800 5801 5802 5803 5804 5805
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet1'/&gt;
    <b>&lt;rom bar='on' file='/etc/fake/boot.bin'/&gt;</b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5806 5807 5808 5809 5810 5811 5812 5813 5814 5815

    <p>
      For hypervisors which support this, you can change how a PCI Network
      device's ROM is presented to the guest. The <code>bar</code>
      attribute can be set to "on" or "off", and determines whether
      or not the device's ROM will be visible in the guest's memory
      map. (In PCI documentation, the "rombar" setting controls the
      presence of the Base Address Register for the ROM). If no rom
      bar is specified, the qemu default will be used (older
      versions of qemu used a default of "off", while newer qemus
5816 5817 5818 5819 5820 5821
      have a default of "on").
      The optional <code>file</code> attribute is used to point to a
      binary file to be presented to the guest as the device's ROM
      BIOS. This can be useful to provide an alternative boot ROM for a
      network device.
      <span class="since">Since 0.9.10 (QEMU and KVM only)</span>.
5822
    </p>
5823
    <h5><a id="elementDomain">Setting up a network backend in a driver domain</a></h5>
5824
<pre>
5825 5826
...
&lt;devices&gt;
5827
  ...
5828 5829 5830 5831 5832 5833 5834
  &lt;interface type='bridge'&gt;
    &lt;source bridge='br0'/&gt;
    <b>&lt;backenddomain name='netvm'/&gt;</b>
  &lt;/interface&gt;
  ...
&lt;/devices&gt;
...</pre>
5835 5836 5837 5838 5839 5840 5841 5842 5843 5844 5845

    <p>
      The optional <code>backenddomain</code> element allows specifying a
      backend domain (aka driver domain) for the interface. Use the
      <code>name</code> attribute to specify the backend domain name. You
      can use it to create a direct network link between domains (so data
      will not go through host system). Use with type 'ethernet' to create
      plain network link, or with type 'bridge' to connect to a bridge inside
      the backend domain.
      <span class="since">Since 1.2.13 (Xen only)</span>
    </p>
5846

5847
    <h5><a id="elementQoS">Quality of service</a></h5>
5848 5849

<pre>
5850 5851 5852 5853 5854 5855 5856 5857 5858 5859 5860 5861
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet0'/&gt;
    <b>&lt;bandwidth&gt;
      &lt;inbound average='1000' peak='5000' floor='200' burst='1024'/&gt;
      &lt;outbound average='128' peak='256' burst='256'/&gt;
    &lt;/bandwidth&gt;</b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5862 5863 5864

    <p>
      This part of interface XML provides setting quality of service. Incoming
J
John Ferlan 已提交
5865 5866 5867 5868
      and outgoing traffic can be shaped independently.
      The <code>bandwidth</code> element and its child elements are described
      in the <a href="formatnetwork.html#elementQoS">QoS</a> section of
      the Network XML.
5869 5870
    </p>

5871
    <h5><a id="elementVlanTag">Setting VLAN tag (on supported network types only)</a></h5>
5872 5873

<pre>
5874 5875 5876 5877 5878 5879 5880 5881 5882 5883 5884 5885 5886 5887 5888 5889 5890 5891 5892 5893
...
&lt;devices&gt;
  &lt;interface type='bridge'&gt;
    <b>&lt;vlan&gt;</b>
      <b>&lt;tag id='42'/&gt;</b>
    <b>&lt;/vlan&gt;</b>
    &lt;source bridge='ovsbr0'/&gt;
    &lt;virtualport type='openvswitch'&gt;
      &lt;parameters interfaceid='09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f'/&gt;
    &lt;/virtualport&gt;
  &lt;/interface&gt;
  &lt;interface type='bridge'&gt;
    <b>&lt;vlan trunk='yes'&gt;</b>
      <b>&lt;tag id='42'/&gt;</b>
      <b>&lt;tag id='123' nativeMode='untagged'/&gt;</b>
    <b>&lt;/vlan&gt;</b>
    ...
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5894 5895 5896

    <p>
      If (and only if) the network connection used by the guest
5897
      supports VLAN tagging transparent to the guest, an
5898
      optional <code>&lt;vlan&gt;</code> element can specify one or
5899 5900 5901 5902 5903 5904 5905 5906 5907
      more VLAN tags to apply to the guest's network
      traffic <span class="since">Since 0.10.0</span>. Network
      connections that support guest-transparent VLAN tagging include
      1) type='bridge' interfaces connected to an Open vSwitch bridge
      <span class="since">Since 0.10.0</span>, 2) SRIOV Virtual
      Functions (VF) used via type='hostdev' (direct device
      assignment) <span class="since">Since 0.10.0</span>, and 3)
      SRIOV VFs used via type='direct' with mode='passthrough'
      (macvtap "passthru" mode) <span class="since">Since
5908
      1.3.5</span>. All other connection types, including standard
5909 5910 5911
      linux bridges and libvirt's own virtual networks, <b>do not</b>
      support it. 802.1Qbh (vn-link) and 802.1Qbg (VEPA) switches
      provide their own way (outside of libvirt) to tag guest traffic
5912 5913 5914 5915 5916 5917 5918 5919 5920
      onto a specific VLAN. Each tag is given in a
      separate <code>&lt;tag&gt;</code> subelement
      of <code>&lt;vlan&gt;</code> (for example: <code>&lt;tag
      id='42'/&gt;</code>). For VLAN trunking of multiple tags (which
      is supported only on Open vSwitch connections),
      multiple <code>&lt;tag&gt;</code> subelements can be specified,
      which implies that the user wants to do VLAN trunking on the
      interface for all the specified tags. In the case that VLAN
      trunking of a single tag is desired, the optional
5921
      attribute <code>trunk='yes'</code> can be added to the toplevel
5922 5923
      <code>&lt;vlan&gt;</code> element to differentiate trunking of a
      single tag from normal tagging.
5924
    </p>
5925
    <p>
5926 5927 5928 5929 5930 5931 5932 5933 5934 5935 5936
      For network connections using Open vSwitch it is also possible
      to configure 'native-tagged' and 'native-untagged' VLAN modes
      <span class="since">Since 1.1.0.</span> This is done with the
      optional <code>nativeMode</code> attribute on
      the <code>&lt;tag&gt;</code> subelement: <code>nativeMode</code>
      may be set to 'tagged' or 'untagged'. The <code>id</code>
      attribute of the <code>&lt;tag&gt;</code> subelement
      containing <code>nativeMode</code> sets which VLAN is considered
      to be the "native" VLAN for this interface, and
      the <code>nativeMode</code> attribute determines whether or not
      traffic for that VLAN will be tagged.
5937 5938
    </p>

5939
    <h5><a id="elementLink">Modifying virtual link state</a></h5>
5940
<pre>
5941 5942 5943 5944 5945 5946 5947 5948 5949
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet0'/&gt;
    <b>&lt;link state='down'/&gt;</b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
5950 5951 5952 5953 5954 5955 5956 5957 5958 5959

    <p>
      This element provides means of setting state of the virtual network link.
      Possible values for attribute <code>state</code> are <code>up</code> and
      <code>down</code>. If <code>down</code> is specified as the value, the interface
      behaves as if it had the network cable disconnected. Default behavior if this
      element is unspecified is to have the link state <code>up</code>.
      <span class="since">Since 0.9.5</span>
    </p>

5960
    <h5><a id="mtu">MTU configuration</a></h5>
5961 5962 5963 5964 5965 5966 5967 5968 5969 5970 5971 5972 5973 5974 5975 5976 5977 5978
<pre>
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet0'/&gt;
    <b>&lt;mtu size='1500'/&gt;</b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>

    <p>
      This element provides means of setting MTU of the virtual network link.
      Currently there is just one attribute <code>size</code> which accepts a
      non-negative integer which specifies the MTU size for the interface.
      <span class="since">Since 3.1.0</span>
    </p>

5979
    <h5><a id="coalesce">Coalesce settings</a></h5>
5980 5981 5982 5983 5984 5985 5986 5987 5988 5989 5990 5991 5992 5993 5994 5995 5996 5997 5998
<pre>
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet0'/&gt;
    <b>&lt;coalesce&gt;
      &lt;rx&gt;
        &lt;frames max='7'/&gt;
      &lt;/rx&gt;
    &lt;/coalesce&gt;</b>
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>

    <p>
      This element provides means of setting coalesce settings for
      some interface devices (currently only type <code>network</code>
      and <code>bridge</code>.  Currently there is just one attribute,
5999
      <code>max</code>, to tweak, in element <code>frames</code> for
6000 6001 6002 6003 6004 6005
      the <code>rx</code> group, which accepts a non-negative integer
      that specifies the maximum number of packets that will be
      received before an interrupt.
      <span class="since">Since 3.3.0</span>
    </p>

6006
    <h5><a id="ipconfig">IP configuration</a></h5>
6007
<pre>
6008 6009 6010 6011 6012 6013 6014 6015 6016 6017
...
&lt;devices&gt;
  &lt;interface type='network'&gt;
    &lt;source network='default'/&gt;
    &lt;target dev='vnet0'/&gt;
    <b>&lt;ip address='192.168.122.5' prefix='24'/&gt;</b>
    <b>&lt;ip address='192.168.122.5' prefix='24' peer='10.0.0.10'/&gt;</b>
    <b>&lt;route family='ipv4' address='192.168.122.0' prefix='24' gateway='192.168.122.1'/&gt;</b>
    <b>&lt;route family='ipv4' address='192.168.122.8' gateway='192.168.122.1'/&gt;</b>
  &lt;/interface&gt;
6018
  ...
6019 6020 6021 6022 6023 6024 6025 6026 6027 6028 6029
  &lt;hostdev mode='capabilities' type='net'&gt;
    &lt;source&gt;
      &lt;interface&gt;eth0&lt;/interface&gt;
    &lt;/source&gt;
    <b>&lt;ip address='192.168.122.6' prefix='24'/&gt;</b>
    <b>&lt;route family='ipv4' address='192.168.122.0' prefix='24' gateway='192.168.122.1'/&gt;</b>
    <b>&lt;route family='ipv4' address='192.168.122.8' gateway='192.168.122.1'/&gt;</b>
  &lt;/hostdev&gt;

&lt;/devices&gt;
...
6030 6031 6032
</pre>

    <p>
6033 6034 6035 6036 6037 6038 6039 6040 6041 6042 6043 6044 6045 6046 6047
      <span class="since">Since 1.2.12</span> network devices and
      hostdev devices with network capabilities can optionally be provided
      one or more IP addresses to set on the network device in the
      guest. Note that some hypervisors or network device types will
      simply ignore them or only use the first one.
      The <code>family</code> attribute can be set to
      either <code>ipv4</code> or <code>ipv6</code>, and the
      <code>address</code> attribute contains the IP address. The
      optional <code>prefix</code> is the number of 1 bits in the
      netmask, and will be automatically set if not specified - for
      IPv4 the default prefix is determined according to the network
      "class" (A, B, or C - see RFC870), and for IPv6 the default
      prefix is 64. The optional <code>peer</code> attribute holds the
      IP address of the other end of a point-to-point network
      device <span class="since">(since 2.1.0)</span>.
6048 6049
    </p>

6050
    <p>
6051 6052 6053 6054 6055 6056
    <span class="since">Since 1.2.12</span> route elements can also be
    added to define IP routes to add in the guest.  The attributes of
    this element are described in the documentation for
    the <code>route</code> element
    in <a href="formatnetwork.html#elementsStaticroute">network
    definitions</a>.  This is used by the LXC driver.
6057 6058
    </p>

6059
<pre>
6060 6061 6062 6063 6064 6065 6066 6067
...
&lt;devices&gt;
  &lt;interface type='ethernet'&gt;
    <b>&lt;source/&gt;</b>
      <b>&lt;ip address='192.168.123.1' prefix='24'/&gt;</b>
      <b>&lt;ip address='10.0.0.10' prefix='24' peer='192.168.122.5'/&gt;</b>
      <b>&lt;route family='ipv4' address='192.168.42.0' prefix='24' gateway='192.168.123.4'/&gt;</b>
    <b>&lt;source/&gt;</b>
6068
    ...
6069
  &lt;/interface&gt;
6070
  ...
6071 6072
&lt;/devices&gt;
...
6073 6074 6075 6076 6077 6078 6079 6080 6081 6082 6083 6084
</pre>

    <p>
      <span class="since">Since 2.1.0</span> network devices of type
      "ethernet" can optionally be provided one or more IP addresses
      and one or more routes to set on the <b>host</b> side of the
      network device. These are configured as subelements of
      the <code>&lt;source&gt;</code> element of the interface, and
      have the same attributes as the similarly named elements used to
      configure the guest side of the interface (described above).
    </p>

6085
    <h5><a id="elementVhostuser">vhost-user interface</a></h5>
M
Michele Paolino 已提交
6086 6087 6088 6089 6090 6091 6092 6093 6094

    <p>
    <span class="since">Since 1.2.7</span> the vhost-user enables the
    communication between a QEMU virtual machine and other userspace process
    using the Virtio transport protocol.  A char dev (e.g. Unix socket) is used
    for the control plane, while the data plane is based on shared memory.
    </p>

<pre>
6095 6096 6097 6098 6099 6100 6101 6102 6103
...
&lt;devices&gt;
  &lt;interface type='vhostuser'&gt;
    &lt;mac address='52:54:00:3b:83:1a'/&gt;
    &lt;source type='unix' path='/tmp/vhost1.sock' mode='server'/&gt;
    &lt;model type='virtio'/&gt;
  &lt;/interface&gt;
  &lt;interface type='vhostuser'&gt;
    &lt;mac address='52:54:00:3b:83:1b'/&gt;
6104 6105 6106
    &lt;source type='unix' path='/tmp/vhost2.sock' mode='client'&gt;
      &lt;reconnect enabled='yes' timeout='10'/&gt;
    &lt;/source&gt;
6107 6108 6109 6110 6111
    &lt;model type='virtio'/&gt;
    &lt;driver queues='5'/&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
M
Michele Paolino 已提交
6112 6113 6114 6115 6116 6117 6118 6119 6120 6121

    <p>
      The <code>&lt;source&gt;</code> element has to be specified
      along with the type of char device.
      Currently, only type='unix' is supported, where the path (the
      directory path of the socket) and mode attributes are required.
      Both <code>mode='server'</code> and <code>mode='client'</code>
      are supported.
      vhost-user requires the virtio model type, thus the
      <code>&lt;model&gt;</code> element is mandatory.
6122 6123 6124 6125 6126 6127 6128
      <span class="since">Since 4.1.0</span> the element has an
      optional child element <code>reconnect</code> which
      configures reconnect timeout if the connection is lost. It
      has two attributes <code>enabled</code> (which accepts
      <code>yes</code> and <code>no</code>) and
      <code>timeout</code> which specifies the amount of seconds
      after which hypervisor tries to reconnect.
M
Michele Paolino 已提交
6129 6130
    </p>

6131
    <h5><a id="elementNwfilter">Traffic filtering with NWFilter</a></h5>
6132 6133 6134 6135 6136 6137 6138 6139 6140 6141 6142

    <p>
    <span class="since">Since 0.8.0</span> an <code>nwfilter</code> profile
    can be assigned to a domain interface, which allows configuring
    traffic filter rules for the virtual machine.

    See the <a href="formatnwfilter.html">nwfilter</a> documentation for more
    complete details.
    </p>

<pre>
6143 6144 6145 6146 6147 6148 6149 6150 6151 6152 6153 6154
...
&lt;devices&gt;
  &lt;interface ...&gt;
    ...
    &lt;filterref filter='clean-traffic'/&gt;
  &lt;/interface&gt;
  &lt;interface ...&gt;
    ...
    &lt;filterref filter='myfilter'&gt;
      &lt;parameter name='IP' value='104.207.129.11'/&gt;
      &lt;parameter name='IP6_ADDR' value='2001:19f0:300:2102::'/&gt;
      &lt;parameter name='IP6_MASK' value='64'/&gt;
6155
      ...
6156 6157 6158 6159
    &lt;/filterref&gt;
  &lt;/interface&gt;
&lt;/devices&gt;
...</pre>
6160 6161 6162 6163 6164 6165 6166 6167 6168 6169 6170

    <p>
      The <code>filter</code> attribute specifies the name of the nwfilter
      to use. Optional <code>&lt;parameter&gt;</code> elements may be
      specified for passing additional info to the nwfilter via the
      <code>name</code> and <code>value</code> attributes. See
      the <a href="formatnwfilter.html#nwfconceptsvars">nwfilter</a>
      docs for info on parameters.
    </p>


6171
    <h4><a id="elementsInput">Input devices</a></h4>
D
Daniel P. Berrange 已提交
6172 6173

    <p>
E
Eric Blake 已提交
6174 6175 6176 6177
      Input devices allow interaction with the graphical framebuffer
      in the guest virtual machine. When enabling the framebuffer, an
      input device is automatically provided. It may be possible to
      add additional devices explicitly, for example,
D
Daniel P. Berrange 已提交
6178 6179 6180
      to provide a graphics tablet for absolute cursor movement.
    </p>

6181
<pre>
6182 6183 6184 6185 6186 6187 6188 6189 6190 6191 6192 6193
...
&lt;devices&gt;
  &lt;input type='mouse' bus='usb'/&gt;
  &lt;input type='keyboard' bus='usb'/&gt;
  &lt;input type='mouse' bus='virtio'/&gt;
  &lt;input type='keyboard' bus='virtio'/&gt;
  &lt;input type='tablet' bus='virtio'/&gt;
  &lt;input type='passthrough' bus='virtio'&gt;
    &lt;source evdev='/dev/input/event1/&gt;
  &lt;/input&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
6194 6195 6196

    <dl>
      <dt><code>input</code></dt>
E
Eric Blake 已提交
6197
      <dd>The <code>input</code> element has one mandatory attribute,
6198 6199 6200
        the <code>type</code> whose value can be 'mouse', 'tablet',
        (<span class="since">since 1.2.2</span>) 'keyboard' or
        (<span class="since">since 1.3.0</span>) 'passthrough'.
6201 6202
        The tablet provides absolute cursor movement,
        while the mouse uses relative movement. The optional
M
Matthew Booth 已提交
6203
        <code>bus</code> attribute can be used to refine the exact device type.
6204 6205
        It takes values "xen" (paravirtualized), "ps2" and "usb" or
        (<span class="since">since 1.3.0</span>) "virtio".</dd>
D
Daniel P. Berrange 已提交
6206 6207
    </dl>

E
Eric Blake 已提交
6208 6209 6210
    <p>
      The <code>input</code> element has an optional
      sub-element <code>&lt;address&gt;</code> which can tie the
6211 6212
      device to a particular PCI
      slot, <a href="#elementsAddress">documented above</a>.
6213 6214
      On S390, <code>address</code> can be used to provide a CCW address for
      an input device (<span class="since">since 4.2.0</span>).
6215 6216 6217 6218

      For type <code>passthrough</code>, the mandatory sub-element <code>source</code>
      must have an <code>evdev</code> attribute containing the absolute path to the
      event device passed through to guests. (KVM only)
E
Eric Blake 已提交
6219
    </p>
D
Daniel P. Berrange 已提交
6220

6221 6222 6223 6224 6225 6226 6227
    <p>
        The subelement <code>driver</code> can be used to tune the virtio
        options of the device:
        <a href="#elementsVirtio">Virtio-specific options</a> can also be
        set. (<span class="since">Since 3.5.0</span>)
    </p>

6228
    <h4><a id="elementsHub">Hub devices</a></h4>
M
Marc-André Lureau 已提交
6229 6230 6231 6232 6233 6234 6235 6236

    <p>
      A hub is a device that expands a single port into several so
      that there are more ports available to connect devices to a host
      system.
    </p>

<pre>
6237 6238 6239 6240 6241
...
&lt;devices&gt;
  &lt;hub type='usb'/&gt;
&lt;/devices&gt;
...</pre>
M
Marc-André Lureau 已提交
6242 6243 6244 6245 6246 6247 6248 6249 6250

    <dl>
      <dt><code>hub</code></dt>
      <dd>The <code>hub</code> element has one mandatory attribute,
        the <code>type</code> whose value can only be 'usb'.</dd>
    </dl>

    <p>
      The <code>hub</code> element has an optional
6251 6252 6253 6254
      sub-element <code>&lt;address&gt;</code>
      with <code>type='usb'</code>which can tie the device to a
      particular controller, <a href="#elementsAddress">documented
      above</a>.
M
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6255 6256
    </p>

6257
    <h4><a id="elementsGraphics">Graphical framebuffers</a></h4>
D
Daniel P. Berrange 已提交
6258 6259 6260 6261 6262 6263 6264 6265

    <p>
      A graphics device allows for graphical interaction with the
      guest OS. A guest will typically have either a framebuffer
      or a text console configured to allow interaction with the
      admin.
    </p>

6266
<pre>
6267 6268 6269 6270 6271 6272 6273 6274 6275 6276 6277 6278 6279
...
&lt;devices&gt;
  &lt;graphics type='sdl' display=':0.0'/&gt;
  &lt;graphics type='vnc' port='5904' sharePolicy='allow-exclusive'&gt;
    &lt;listen type='address' address='1.2.3.4'/&gt;
  &lt;/graphics&gt;
  &lt;graphics type='rdp' autoport='yes' multiUser='yes' /&gt;
  &lt;graphics type='desktop' fullscreen='yes'/&gt;
  &lt;graphics type='spice'&gt;
    &lt;listen type='network' network='rednet'/&gt;
  &lt;/graphics&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
6280 6281 6282

    <dl>
      <dt><code>graphics</code></dt>
6283 6284 6285 6286 6287 6288
      <dd>
        <p>
          The <code>graphics</code> element has a mandatory <code>type</code>
          attribute which takes the value <code>sdl</code>, <code>vnc</code>,
          <code>spice</code>, <code>rdp</code> or <code>desktop</code>:
        </p>
6289
        <dl>
6290
          <dt><code>sdl</code></dt>
6291
          <dd>
6292 6293 6294 6295 6296 6297 6298
            <p>
              This displays a window on the host desktop, it can take 3 optional
              arguments: a <code>display</code> attribute for the display to use,
              an <code>xauth</code> attribute for the authentication identifier,
              and an optional <code>fullscreen</code> attribute accepting values
              <code>yes</code> or <code>no</code>.
            </p>
6299 6300 6301 6302 6303 6304

            <p>
              You can use a <code>gl</code> with the <code>enable="yes"</code>
              property to enable OpenGL support in SDL. Likewise you can
              explicitly disable OpenGL support with <code>enable="no"</code>.
            </p>
6305
          </dd>
6306
          <dt><code>vnc</code></dt>
6307
          <dd>
6308 6309 6310 6311 6312
            <p>
              Starts a VNC server. The <code>port</code> attribute specifies
              the TCP port number (with -1 as legacy syntax indicating that it
              should be auto-allocated). The <code>autoport</code> attribute is
              the new preferred syntax for indicating auto-allocation of the TCP
6313
              port to use. The <code>passwd</code> attribute provides a VNC
6314 6315 6316 6317
              password in clear text. If the <code>passwd</code> attribute is
              set to an empty string, then VNC access is disabled. The
              <code>keymap</code> attribute specifies the keymap to use. It is
              possible to set a limit on the validity of the password by giving
V
Ville Skyttä 已提交
6318
              a timestamp <code>passwdValidTo='2010-04-09T15:51:00'</code>
6319 6320
              assumed to be in UTC. The <code>connected</code> attribute allows
              control of connected client during password changes. VNC accepts
6321 6322 6323 6324 6325 6326 6327 6328 6329 6330 6331 6332 6333 6334 6335 6336 6337 6338 6339 6340 6341 6342 6343 6344 6345
              <code>keep</code> value only <span class="since">since 0.9.3</span>.
              NB, this may not be supported by all hypervisors.
            </p>
            <p>
              The optional <code>sharePolicy</code> attribute specifies vnc
              server display sharing policy. <code>allow-exclusive</code> allows
              clients to ask for exclusive access by dropping other connections.
              Connecting multiple clients in parallel requires all clients asking
              for a shared session (vncviewer: -Shared switch). This is
              the default value. <code>force-shared</code> disables exclusive
              client access, every connection has to specify -Shared switch for
              vncviewer. <code>ignore</code> welcomes every connection
              unconditionally <span class="since">since 1.0.6</span>.
            </p>
            <p>
              Rather than using listen/port, QEMU supports a <code>socket</code>
              attribute for listening on a unix domain socket path
              <span class="since">Since 0.8.8</span>.
            </p>
            <p>
              For VNC WebSocket functionality, <code>websocket</code> attribute
              may be used to specify port to listen on (with -1 meaning
              auto-allocation and <code>autoport</code> having no effect due to
              security reasons) <span class="since">Since 1.0.6</span>.
            </p>
6346
          </dd>
6347
          <dt><code>spice</code> <span class="since">Since 0.8.6</span></dt>
6348
          <dd>
E
Eric Blake 已提交
6349
            <p>
6350 6351 6352 6353 6354
              Starts a SPICE server. The <code>port</code> attribute specifies
              the TCP port number (with -1 as legacy syntax indicating that it
              should be auto-allocated), while <code>tlsPort</code> gives
              an alternative secure port number. The <code>autoport</code>
              attribute is the new preferred syntax for indicating
6355
              auto-allocation of needed port numbers. The <code>passwd</code>
6356 6357 6358 6359
              attribute provides a SPICE password in clear text. If the
              <code>passwd</code> attribute is set to an empty string, then
              SPICE access is disabled. The <code>keymap</code> attribute
              specifies the keymap to use. It is possible to set a limit on
V
Ville Skyttä 已提交
6360
              the validity of the password by giving a timestamp
6361 6362
              <code>passwdValidTo='2010-04-09T15:51:00'</code> assumed to be
              in UTC.
6363 6364 6365 6366 6367 6368 6369
            </p>
            <p>
              The <code>connected</code> attribute allows control of connected
              client during password changes. SPICE accepts <code>keep</code> to
              keep client connected, <code>disconnect</code> to disconnect client
              and <code>fail</code> to fail changing password . NB, this may not
              be supported by all hypervisors.
6370
              <span class="since">Since 0.9.3</span>
6371 6372
            </p>
            <p>
6373 6374
              The <code>defaultMode</code> attribute sets the default channel
              security policy, valid values are <code>secure</code>,
6375 6376 6377 6378
              <code>insecure</code> and the default <code>any</code> (which is
              secure if possible, but falls back to insecure rather than erroring
              out if no secure path is available).
              <span class="since">Since 0.9.12</span>
E
Eric Blake 已提交
6379 6380
            </p>
            <p>
6381 6382 6383 6384 6385 6386 6387 6388
              When SPICE has both a normal and TLS secured TCP port configured,
              it can be desirable to restrict what channels can be run on each
              port. This is achieved by adding one or more <code>&lt;channel&gt;
              </code> elements inside the main <code>&lt;graphics&gt;</code>
              element and setting the <code>mode</code> attribute to either
              <code>secure</code> or <code>insecure</code>. Setting the mode
              attribute overrides the default value as set by
              the <code>defaultMode</code> attribute. (Note that specifying
6389
              <code>any</code> as mode discards the entry as the channel would
6390 6391 6392
              inherit the default mode anyways.) Valid channel names include
              <code>main</code>, <code>display</code>, <code>inputs</code>,
              <code>cursor</code>, <code>playback</code>, <code>record</code>
6393
              (all <span class="since"> since 0.8.6</span>);
6394 6395
              <code>smartcard</code> (<span class="since">since 0.8.8</span>);
              and <code>usbredir</code> (<span class="since">since 0.9.12</span>).
E
Eric Blake 已提交
6396 6397
            </p>
            <pre>
6398 6399 6400 6401 6402 6403 6404 6405
&lt;graphics type='spice' port='-1' tlsPort='-1' autoport='yes'&gt;
  &lt;channel name='main' mode='secure'/&gt;
  &lt;channel name='record' mode='insecure'/&gt;
  &lt;image compression='auto_glz'/&gt;
  &lt;streaming mode='filter'/&gt;
  &lt;clipboard copypaste='no'/&gt;
  &lt;mouse mode='client'/&gt;
  &lt;filetransfer enable='no'/&gt;
6406
  &lt;gl enable='yes' rendernode='/dev/dri/by-path/pci-0000:00:02.0-render'/&gt;
6407
&lt;/graphics&gt;</pre>
6408
            <p>
6409 6410 6411 6412 6413 6414 6415 6416 6417 6418 6419 6420
              Spice supports variable compression settings for audio, images and
              streaming. These settings are accessible via the <code>compression
              </code> attribute in all following elements: <code>image</code> to
              set image compression (accepts <code>auto_glz</code>,
              <code>auto_lz</code>, <code>quic</code>, <code>glz</code>,
              <code>lz</code>, <code>off</code>), <code>jpeg</code> for JPEG
              compression for images over wan (accepts <code>auto</code>,
              <code>never</code>, <code>always</code>), <code>zlib</code> for
              configuring wan image compression (accepts <code>auto</code>,
              <code>never</code>, <code>always</code>)  and <code>playback</code>
              for enabling audio stream compression (accepts <code>on</code> or
              <code>off</code>). <span class="since">Since 0.9.1</span>
6421
            </p>
6422
            <p>
6423 6424 6425 6426
              Streaming mode is set by the <code>streaming</code> element,
              settings its <code>mode</code> attribute to one of
              <code>filter</code>, <code>all</code> or <code>off</code>.
              <span class="since">Since 0.9.2</span>
6427
            </p>
6428
            <p>
6429 6430 6431 6432
              Copy &amp; Paste functionality (via Spice agent) is set by the
              <code>clipboard</code> element. It is enabled by default, and can
              be disabled by setting the <code>copypaste</code> property to
              <code>no</code>. <span class="since">Since 0.9.3</span>
6433
            </p>
P
Peng Zhou 已提交
6434
            <p>
6435 6436 6437 6438
              Mouse mode is set by the <code>mouse</code> element, setting its
              <code>mode</code> attribute to one of <code>server</code> or
              <code>client</code>. If no mode is specified, the qemu default will
              be used (client mode). <span class="since">Since 0.9.11</span>
P
Peng Zhou 已提交
6439
            </p>
6440 6441
            <p>
              File transfer functionality (via Spice agent) is set using the
6442 6443 6444
              <code>filetransfer</code> element. It is enabled by default, and
              can be disabled by setting the <code>enable</code> property to
              <code>no</code>. <span class="since">Since 1.2.2</span>
6445
            </p>
6446
            <p>
6447 6448 6449
              Spice may provide accelerated server-side rendering with OpenGL.
              You can enable or disable OpenGL support explicitly with
              the <code>gl</code> element, by setting the <code>enable</code>
6450
              property. (QEMU only, <span class="since">since 1.3.3</span>).
6451
            </p>
6452 6453 6454 6455 6456
            <p>
              By default, QEMU will pick the first available GPU DRM render node.
              You may specify a DRM render node path to use instead. (QEMU only,
              <span class="since">since 3.1.0</span>).
            </p>
6457
          </dd>
6458
          <dt><code>rdp</code></dt>
6459
          <dd>
6460 6461 6462 6463 6464
            <p>
              Starts a RDP server. The <code>port</code> attribute specifies the
              TCP port number (with -1 as legacy syntax indicating that it should
              be auto-allocated). The <code>autoport</code> attribute is the new
              preferred syntax for indicating auto-allocation of the TCP port to
6465 6466 6467 6468
              use. In the VirtualBox driver, the <code>autoport</code> will make
              the hypervisor pick available port from 3389-3689 range when the VM
              is started. The chosen port will be reflected in the <code>port</code>
              attribute. The <code>multiUser</code> attribute is a boolean deciding
6469
              whether multiple simultaneous connections to the VM are permitted.
6470
              The <code>replaceUser</code> attribute is a boolean deciding whether
6471 6472 6473 6474
              the existing connection must be dropped and a new connection must
              be established by the VRDP server, when a new client connects in
              single connection mode.
            </p>
6475
          </dd>
6476
          <dt><code>desktop</code></dt>
6477
          <dd>
6478 6479 6480 6481 6482 6483 6484
            <p>
              This value is reserved for VirtualBox domains for the moment. It
              displays a window on the host desktop, similarly to "sdl", but
              using the VirtualBox viewer. Just like "sdl", it accepts
              the optional attributes <code>display</code> and
              <code>fullscreen</code>.
            </p>
6485 6486 6487 6488 6489
          </dd>
        </dl>
      </dd>
    </dl>

6490
    <p>
6491 6492 6493 6494 6495 6496
      Graphics device uses a <code>&lt;listen&gt;</code> to set up where
      the device should listen for clients. It has a mandatory attribute
      <code>type</code> which specifies the listen type. Only <code>vnc</code>,
      <code>spice</code> and <code>rdp</code> supports <code>&lt;listen&gt;
      </code> element. <span class="since">Since 0.9.4</span>.
      Available types are:
6497 6498 6499
    </p>
    <dl>
      <dt><code>address</code></dt>
6500 6501 6502 6503 6504 6505 6506
      <dd>
        <p>
          Tells a graphics device to use an address specified in the
          <code>address</code> attribute, which will contain either an IP address
          or hostname (which will be resolved to an IP address via a DNS query)
          to listen on.
        </p>
6507 6508 6509 6510 6511 6512 6513 6514 6515
        <p>
          It is possible to omit the <code>address</code> attribute in order to
          use an address from config files <span class="since">Since 1.3.5</span>.
        </p>
        <p>
          The <code>address</code> attribute is duplicated as <code>listen</code>
          attribute in <code>graphics</code> element for backward compatibility.
          If both are provided they must be equal.
        </p>
6516 6517
      </dd>
      <dt><code>network</code></dt>
6518 6519 6520 6521 6522 6523 6524 6525 6526 6527 6528 6529 6530 6531 6532
      <dd>
        <p>
          This is used to specify an existing network in the <code>network</code>
          attribute from libvirt's list of configured networks. The named network
          configuration will be examined to determine an appropriate listen
          address and the address will be stored in live XML in <code>address
          </code> attribute. For example, if the network has an IPv4 address in
          its configuration (e.g. if it has a forward type of <code>route</code>,
          <code>nat</code>, or no forward type (isolated)), the first IPv4
          address listed in the network's configuration will be used.
          If the network is describing a host bridge, the first IPv4 address
          associated with that bridge device will be used, and if the network is
          describing one of the 'direct' (macvtap) modes, the first IPv4 address
          of the first forward dev will be used.
        </p>
6533
      </dd>
6534
      <dt><code>socket</code> <span class="since">since 2.0.0 (QEMU only)</span></dt>
6535 6536 6537 6538 6539
      <dd>
        <p>
          This listen type tells a graphics server to listen on unix socket.
          Attribute <code>socket</code> contains a path to unix socket. If this
          attribute is omitted libvirt will generate this path for you.
6540
          Supported by graphics type <code>vnc</code> and <code>spice</code>.
6541 6542 6543 6544 6545 6546 6547
        </p>
        <p>
          For <code>vnc</code> graphics be backward compatible
          the <code>socket</code> attribute of first <code>listen</code> element
          is duplicated as <code>socket</code> attribute in <code>graphics</code>
          element. If <code>graphics</code> element contains a <code>socket</code>
          attribute all <code>listen</code> elements are ignored.
6548 6549
        </p>
      </dd>
6550
      <dt><code>none</code> <span class="since">since 2.0.0 (QEMU only)</span></dt>
P
Pavel Hrdina 已提交
6551 6552 6553 6554 6555 6556 6557
      <dd>
        <p>
          This listen type doesn't have any other attribute. Libvirt supports
          passing a file descriptor through our APIs virDomainOpenGraphics() and
          virDomainOpenGraphicsFD(). No other listen types are allowed if this
          one is used and the graphics device doesn't listen anywhere. You need
          to use one of the two APIs to pass a FD to QEMU in order to connect to
6558 6559
          this graphics device. Supported by graphics type <code>vnc</code> and
          <code>spice</code>.
P
Pavel Hrdina 已提交
6560 6561
        </p>
      </dd>
6562 6563
    </dl>

6564
    <h4><a id="elementsVideo">Video devices</a></h4>
6565 6566 6567 6568
    <p>
      A video device.
    </p>

6569
<pre>
6570 6571 6572 6573 6574 6575 6576 6577 6578
...
&lt;devices&gt;
  &lt;video&gt;
    &lt;model type='vga' vram='16384' heads='1'&gt;
      &lt;acceleration accel3d='yes' accel2d='yes'/&gt;
    &lt;/model&gt;
  &lt;/video&gt;
&lt;/devices&gt;
...</pre>
6579 6580 6581

    <dl>
      <dt><code>video</code></dt>
6582
      <dd>
6583 6584 6585 6586 6587 6588 6589 6590 6591 6592 6593 6594 6595 6596
        <p>
          The <code>video</code> element is the container for describing
          video devices. For backwards compatibility, if no <code>video</code>
          is set but there is a <code>graphics</code> in domain xml, then
          libvirt will add a default <code>video</code> according to the guest
          type.
        </p>
        <p>
          For a guest of type "kvm", the default <code>video</code> is:
          <code>type</code> with value "cirrus", <code>vram</code> with value
          "16384" and <code>heads</code> with value "1". By default, the first
          video device in domain xml is the primary one, but the optional
          attribute <code>primary</code> (<span class="since">since 1.0.2</span>)
          with value 'yes' can be used to mark the primary in cases of multiple
6597 6598
          video device. The non-primary must be type of "qxl" or
          (<span class="since">since 2.4.0</span>) "virtio".
6599
        </p>
6600
      </dd>
6601

6602 6603
      <dt><code>model</code></dt>
      <dd>
6604 6605 6606
        <p>
          The <code>model</code> element has a mandatory <code>type</code>
          attribute which takes the value "vga", "cirrus", "vmvga", "xen",
F
Fabian Freyer 已提交
6607
          "vbox", "qxl" (<span class="since">since 0.8.6</span>),
M
Marc-André Lureau 已提交
6608
          "virtio" (<span class="since">since 1.3.0</span>)
F
Fabian Freyer 已提交
6609
          or "gop" (<span class="since">since 3.2.0</span>)
M
Marc-André Lureau 已提交
6610
          depending on the hypervisor features available.
6611 6612 6613 6614
        </p>
        <p>
          You can provide the amount of video memory in kibibytes (blocks of
          1024 bytes) using <code>vram</code>. This is supported only for guest
6615
          type of "libxl", "vz", "qemu", "vbox", "vmx" and "xen". If no
6616 6617 6618 6619 6620
          value is provided the default is used. If the size is not a power of
          two it will be rounded to closest one.
        </p>
        <p>
          The number of screen can be set using <code>heads</code>. This is
6621
          supported only for guests type of "vz", "kvm", "vbox" and "vmx".
6622 6623
        </p>
        <p>
6624 6625 6626
          For guest type of "kvm" or "qemu" and model type "qxl" there are
          optional attributes. Attribute <code>ram</code> (<span class="since">
          since 1.0.2</span>) specifies the size of the primary bar, while the
6627
          attribute <code>vram</code> specifies the secondary bar size.
6628 6629 6630 6631 6632
          If <code>ram</code> or <code>vram</code> are not supplied a default
          value is used. The <code>ram</code> should also be rounded to power of
          two as <code>vram</code>. There is also optional attribute
          <code>vgamem</code> (<span class="since">since 1.2.11</span>) to set
          the size of VGA framebuffer for fallback mode of QXL device.
6633
          Attribute <code>vram64</code> (<span class="since">since 1.3.3</span>)
6634
          extends secondary bar and makes it addressable as 64bit memory.
6635
        </p>
6636 6637 6638 6639
      </dd>

      <dt><code>acceleration</code></dt>
      <dd>
6640 6641 6642 6643 6644 6645 6646 6647 6648 6649 6650
        Configure if video acceleration should be enabled.
        <dl>
        <dt><code>accel2d</code></dt>
        <dd>Enable 2D acceleration (for vbox driver only,
        <span class="since">since 0.7.1</span>)</dd>

        <dt><code>accel3d</code></dt>
        <dd>Enable 3D acceleration (for vbox driver
        <span class="since">since 0.7.1</span>, qemu driver
        <span class="since">since 1.3.0</span>)</dd>
        </dl>
6651
      </dd>
E
Eric Blake 已提交
6652 6653 6654 6655 6656

      <dt><code>address</code></dt>
      <dd>
        The optional <code>address</code> sub-element can be used to
        tie the video device to a particular PCI slot.
6657 6658 6659
        On S390, <code>address</code> can be used to provide the
        CCW address for the video device (<span class="since">
        since 4.2.0</span>).
E
Eric Blake 已提交
6660
      </dd>
J
Ján Tomko 已提交
6661 6662 6663 6664 6665 6666 6667 6668

      <dt><code>driver</code></dt>
      <dd>
        The subelement <code>driver</code> can be used to tune the device:
        <dl>
          <dt>virtio options</dt>
          <dd>
          <a href="#elementsVirtio">Virtio-specific options</a> can also be
6669 6670 6671 6672 6673 6674 6675 6676
          set (<span class="since">Since 3.5.0</span>)
          </dd>
          <dt>VGA configuration</dt>
          <dd>
          Control how the video devices exposed to the guest using the
          <code>vgaconf</code> attribute which takes the value "io", "on" or "off".
          At present, it's only applicable to the bhyve's "gop" video model type
          (<span class="since">Since 3.5.0</span>)
J
Ján Tomko 已提交
6677 6678 6679
          </dd>
        </dl>
      </dd>
D
Daniel P. Berrange 已提交
6680 6681
    </dl>

6682
    <h4><a id="elementsConsole">Consoles, serial, parallel &amp; channel devices</a></h4>
D
Daniel P. Berrange 已提交
6683 6684 6685

    <p>
      A character device provides a way to interact with the virtual machine.
6686 6687
      Paravirtualized consoles, serial ports, parallel ports and channels are
      all classed as character devices and so represented using the same syntax.
D
Daniel P. Berrange 已提交
6688 6689
    </p>

6690
<pre>
6691 6692 6693 6694 6695 6696 6697 6698 6699 6700 6701 6702 6703 6704 6705 6706 6707 6708 6709 6710 6711 6712 6713 6714 6715 6716
...
&lt;devices&gt;
  &lt;parallel type='pty'&gt;
    &lt;source path='/dev/pts/2'/&gt;
    &lt;target port='0'/&gt;
  &lt;/parallel&gt;
  &lt;serial type='pty'&gt;
    &lt;source path='/dev/pts/3'/&gt;
    &lt;target port='0'/&gt;
  &lt;/serial&gt;
  &lt;serial type='file'&gt;
    &lt;source path='/tmp/file' append='on'&gt;
      &lt;seclabel model='dac' relabel='no'/&gt;
    &lt;/source&gt;
    &lt;target port='0'/&gt;
  &lt;/serial&gt;
  &lt;console type='pty'&gt;
    &lt;source path='/dev/pts/4'/&gt;
    &lt;target port='0'/&gt;
  &lt;/console&gt;
  &lt;channel type='unix'&gt;
    &lt;source mode='bind' path='/tmp/guestfwd'/&gt;
    &lt;target type='guestfwd' address='10.0.2.1' port='4600'/&gt;
  &lt;/channel&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
6717

6718 6719 6720 6721 6722
    <p>
      In each of these directives, the top-level element name (parallel, serial,
      console, channel) describes how the device is presented to the guest. The
      guest interface is configured by the <code>target</code> element.
    </p>
D
Daniel P. Berrange 已提交
6723

6724 6725 6726 6727 6728 6729
    <p>
      The interface presented to the host is given in the <code>type</code>
      attribute of the top-level element. The host interface is
      configured by the <code>source</code> element.
    </p>

6730 6731 6732 6733 6734 6735 6736 6737
    <p>
      The <code>source</code> element may contain an optional
      <code>seclabel</code> to override the way that labelling
      is done on the socket path.  If this element is not present,
      the <a href="#seclabel">security label is inherited from
        the per-domain setting</a>.
    </p>

6738 6739 6740 6741 6742 6743 6744 6745
    <p>
      If the interface <code>type</code> presented to the host is "file",
      then the <code>source</code> element may contain an optional attribute
      <code>append</code> that specifies whether or not the information in
      the file should be preserved on domain restart. Allowed values are
      "on" and "off" (default). <span class="since">Since 1.3.1</span>.
    </p>

6746
    <p>
B
Boris Fiuczynski 已提交
6747
      Regardless of the <code>type</code>, character devices can
6748 6749
      have an optional log file associated with them. This is
      expressed via a <code>log</code> sub-element, with a
B
Boris Fiuczynski 已提交
6750 6751 6752
      <code>file</code> attribute. There can also be an <code>append</code>
      attribute which takes the same values described above.
      <span class="since">Since 1.3.3</span>.
6753 6754 6755
    </p>

    <pre>
6756 6757 6758
...
&lt;log file="/var/log/libvirt/qemu/guestname-serial0.log" append="off"/&gt;
...</pre>
6759

E
Eric Blake 已提交
6760 6761 6762 6763 6764 6765 6766 6767
    <p>
      Each character device element has an optional
      sub-element <code>&lt;address&gt;</code> which can tie the
      device to a
      particular <a href="#elementsControllers">controller</a> or PCI
      slot.
    </p>

6768 6769 6770 6771 6772 6773 6774 6775 6776 6777 6778
    <p>
      For character device with type <code>unix</code> or <code>tcp</code>
      the <code>source</code> has an optional element <code>reconnect</code>
      which configures reconnect timeout if the connection is lost.
      There are two attributes, <code>enabled</code> where possible
      values are "yes" and "no" and <code>timeout</code> which is in
      seconds. The <code>reconnect</code> attribute is valid only
      for <code>connect</code> mode.
      <span class="since">Since 3.7.0 (QEMU driver only)</span>.
    </p>

6779
    <h5><a id="elementsCharGuestInterface">Guest interface</a></h5>
6780 6781 6782 6783 6784 6785

    <p>
      A character device presents itself to the guest as one of the following
      types.
    </p>

6786
    <h6><a id="elementCharParallel">Parallel port</a></h6>
6787

6788
<pre>
6789 6790 6791 6792 6793 6794 6795 6796
...
&lt;devices&gt;
  &lt;parallel type='pty'&gt;
    &lt;source path='/dev/pts/2'/&gt;
    &lt;target port='0'/&gt;
  &lt;/parallel&gt;
&lt;/devices&gt;
...</pre>
6797 6798 6799

    <p>
      <code>target</code> can have a <code>port</code> attribute, which
6800
      specifies the port number. Ports are numbered starting from 0. There are
6801 6802 6803
      usually 0, 1 or 2 parallel ports.
    </p>

6804
    <h6><a id="elementCharSerial">Serial port</a></h6>
6805

6806
<pre>
6807 6808
...
&lt;devices&gt;
6809
  &lt;!-- Serial port --&gt;
6810 6811 6812 6813 6814
  &lt;serial type='pty'&gt;
    &lt;source path='/dev/pts/3'/&gt;
    &lt;target port='0'/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
6815 6816 6817 6818 6819 6820 6821
...</pre>

<pre>
...
&lt;devices&gt;
  &lt;!-- USB serial port --&gt;
  &lt;serial type='pty'&gt;
6822 6823 6824
    &lt;target type='usb-serial' port='0'&gt;
      &lt;model name='usb-serial'/&gt;
    &lt;/target&gt;
6825 6826 6827
    &lt;address type='usb' bus='0' port='1'/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
6828
...</pre>
6829 6830

    <p>
6831 6832 6833 6834 6835 6836
      The <code>target</code> element can have an optional <code>port</code>
      attribute, which specifies the port number (starting from 0), and an
      optional <code>type</code> attribute: valid values are,
      <span class="since">since 1.0.2</span>, <code>isa-serial</code> (usable
      with x86 guests), <code>usb-serial</code> (usable whenever USB support
      is available) and <code>pci-serial</code> (usable whenever PCI support
6837
      is available); <span class="since">since 3.10.0</span>,
6838 6839 6840
      <code>spapr-vio-serial</code> (usable with ppc64/pseries guests),
      <code>system-serial</code> (usable with aarch64/virt guests) and
      <code>sclp-serial</code> (usable with s390 and s390x guests) are
6841
      available as well.
6842 6843
    </p>

6844 6845 6846 6847 6848 6849 6850
    <p>
      <span class="since">Since 3.10.0</span>, the <code>target</code>
      element can have an optional <code>model</code> subelement;
      valid values for its <code>name</code> attribute are:
      <code>isa-serial</code> (usable with the <code>isa-serial</code> target
      type); <code>usb-serial</code> (usable with the <code>usb-serial</code>
      target type); <code>pci-serial</code>
6851 6852
      (usable with the <code>pci-serial</code> target type);
      <code>spapr-vty</code> (usable with the <code>spapr-vio-serial</code>
6853
      target type); <code>pl011</code> (usable with the
6854 6855 6856
      <code>system-serial</code> target type); <code>sclpconsole</code> and
      <code>sclplmconsole</code> (usable with the <code>sclp-serial</code>
      target type).
6857 6858
    </p>

6859
    <p>
6860 6861
      If any of the attributes is not specified by the user, libvirt will
      choose a value suitable for most users.
6862 6863
    </p>

6864
    <p>
6865
      Most target types support configuring the guest-visible device
6866 6867
      address as <a href="#elementsAddress">documented above</a>; more
      specifically, acceptable address types are <code>isa</code> (for
6868 6869
      <code>isa-serial</code>), <code>usb</code> (for <code>usb-serial</code>),
      <code>pci</code> (for <code>pci-serial</code>) and <code>spapr-vio</code>
6870
      (for <code>spapr-vio-serial</code>). The <code>system-serial</code>
6871 6872
      and <code>sclp-serial</code> target types don't support specifying an
      address.
6873
    </p>
C
Cole Robinson 已提交
6874 6875

    <p>
6876 6877
      For the relationship between serial ports and consoles,
      <a href="#elementCharSerialAndConsole">see below</a>.
6878 6879
    </p>

6880 6881
    <h6><a id="elementCharConsole">Console</a></h6>

6882
<pre>
6883 6884
...
&lt;devices&gt;
6885
  &lt;!-- Serial console --&gt;
6886
  &lt;console type='pty'&gt;
6887
    &lt;source path='/dev/pts/2'/&gt;
6888
   &lt;target type='serial' port='0'/&gt;
6889
  &lt;/console&gt;
6890 6891
&lt;/devices&gt;
...</pre>
6892

6893 6894
<pre>
...
6895
&lt;devices&gt;
6896 6897 6898 6899 6900 6901 6902
  &lt;!-- KVM virtio console --&gt;
  &lt;console type='pty'&gt;
    &lt;source path='/dev/pts/5'/&gt;
    &lt;target type='virtio' port='0'/&gt;
  &lt;/console&gt;
&lt;/devices&gt;
...</pre>
6903

6904 6905 6906 6907 6908 6909 6910 6911 6912 6913 6914 6915 6916 6917 6918 6919 6920
    <p>
      The <code>console</code> element is used to represent interactive
      serial consoles. Depending on the type of guest in use and the specifics
      of the configuration, the <code>console</code> element might represent
      the same device as an existing <code>serial</code> element or a separate
      device.
    </p>

    <p>
      A <code>target</code> subelement is supported and works the same
      way as with the <code>serial</code> element
      (<a href="#elementCharSerial">see above</a> for details).
      Valid values for the <code>type</code> attribute are:
      <code>serial</code> (described below);
      <code>virtio</code> (usable whenever VirtIO support is available);
      <code>xen</code>, <code>lxc</code>, <code>uml</code> and
      <code>openvz</code> (available when the corresponding hypervisor is in
6921 6922 6923 6924 6925
      use). <code>sclp</code> and <code>sclplm</code> (usable for s390 and
      s390x QEMU guests) are supported for compatibility reasons but should
      not be used for new guests: use the <code>sclpconsole</code> and
      <code>sclplmconsole</code> target models, respectively, with the
      <code>serial</code> element instead.
6926 6927 6928 6929 6930 6931 6932 6933 6934 6935 6936 6937 6938 6939 6940 6941 6942 6943 6944 6945 6946 6947 6948 6949 6950 6951 6952 6953 6954 6955 6956 6957 6958 6959 6960 6961 6962 6963 6964 6965 6966 6967 6968 6969 6970 6971 6972 6973 6974 6975 6976 6977 6978 6979 6980 6981 6982 6983 6984
    </p>

    <p>
      Of the target types listed above, <code>serial</code> is special in
      that it doesn't represents a separate device, but rather the same
      device as the first <code>serial</code> element. Due to this, there can
      only be a single <code>console</code> element with target type
      <code>serial</code> per guest.
    </p>

    <p>
      Virtio consoles are usually accessible as <code>/dev/hvc[0-7]</code>
      from inside the guest; for more information, see
      <a href="http://fedoraproject.org/wiki/Features/VirtioSerial">http://fedoraproject.org/wiki/Features/VirtioSerial</a>.
      <span class="since">Since 0.8.3</span>
    </p>

    <p>
      For the relationship between serial ports and consoles,
      <a href="#elementCharSerialAndConsole">see below</a>.
    </p>

    <h6><a id="elementCharSerialAndConsole">Relationship between serial ports and consoles</a></h6>

    <p>
      Due to hystorical reasons, the <code>serial</code> and
      <code>console</code> elements have partially overlapping scopes.
    </p>

    <p>
      In general, both elements are used to configure one or more serial
      consoles to be used for interacting with the guest. The main difference
      between the two is that <code>serial</code> is used for emulated,
      usually native, serial consoles, whereas <code>console</code> is used
      for paravirtualized ones.
    </p>

    <p>
      Both emulated and paravirtualized serial consoles have advantages and
      disadvantages:
    </p>

    <ul>
      <li>
        emulated serial consoles are usually initialized much earlier than
        paravirtualized ones, so they can be used to control the bootloader
        and display both firmware and early boot messages;
      </li>
      <li>
        on several platforms, there can only be a single emulated serial
        console per guest but paravirtualized consoles don't suffer from the
        same limitation.
      </li>
    </ul>

    <p>
      A configuration such as:
    </p>

6985
<pre>
6986
...
6987
&lt;devices&gt;
6988 6989 6990
  &lt;console type='pty'&gt;
    &lt;target type='serial'/&gt;
  &lt;/console&gt;
6991
  &lt;console type='pty'&gt;
6992
    &lt;target type='virtio'/&gt;
6993 6994 6995
  &lt;/console&gt;
&lt;/devices&gt;
...</pre>
6996

6997
    <p>
6998 6999 7000 7001 7002 7003 7004 7005 7006 7007 7008 7009 7010 7011
      will work on any platform and will result in one emulated serial console
      for early boot logging / interactive / recovery use, and one
      paravirtualized serial console to be used eg. as a side channel. Most
      people will be fine with having just the first <code>console</code>
      element in their configuration.
    </p>

    <p>
      Note that, due to the compatibility concerns mentioned earlier, all the
      following configurations:
    </p>

<pre>
...
7012
&lt;devices&gt;
7013 7014 7015 7016 7017 7018
  &lt;serial type='pty'/&gt;
&lt;/devices&gt;
...</pre>

<pre>
...
7019
&lt;devices&gt;
7020 7021 7022 7023 7024 7025
  &lt;console type='pty'/&gt;
&lt;/devices&gt;
...</pre>

<pre>
...
7026
&lt;devices&gt;
7027 7028 7029 7030 7031 7032 7033 7034
  &lt;serial type='pty'/&gt;
  &lt;console type='pty'/&gt;
&lt;/devices&gt;
...</pre>

    <p>
      will be treated the same and will result in a single emulated serial
      console being available to the guest.
7035 7036
    </p>

7037
    <h6><a id="elementCharChannel">Channel</a></h6>
7038 7039 7040 7041 7042 7043

    <p>
      This represents a private communication channel between the host and the
      guest.
    </p>

7044
<pre>
7045 7046 7047 7048 7049 7050 7051 7052 7053 7054 7055 7056 7057 7058 7059 7060 7061 7062 7063 7064
...
&lt;devices&gt;
  &lt;channel type='unix'&gt;
    &lt;source mode='bind' path='/tmp/guestfwd'/&gt;
    &lt;target type='guestfwd' address='10.0.2.1' port='4600'/&gt;
  &lt;/channel&gt;

  &lt;!-- KVM virtio channel --&gt;
  &lt;channel type='pty'&gt;
    &lt;target type='virtio' name='arbitrary.virtio.serial.port.name'/&gt;
  &lt;/channel&gt;
  &lt;channel type='unix'&gt;
    &lt;source mode='bind' path='/var/lib/libvirt/qemu/f16x86_64.agent'/&gt;
    &lt;target type='virtio' name='org.qemu.guest_agent.0' state='connected'/&gt;
  &lt;/channel&gt;
  &lt;channel type='spicevmc'&gt;
    &lt;target type='virtio' name='com.redhat.spice.0'/&gt;
  &lt;/channel&gt;
&lt;/devices&gt;
...</pre>
7065 7066 7067 7068 7069 7070 7071 7072 7073 7074 7075 7076 7077 7078

    <p>
      This can be implemented in a variety of ways. The specific type of
      channel is given in the <code>type</code> attribute of the
      <code>target</code> element. Different channel types have different
      <code>target</code> attributes.
    </p>

    <dl>
      <dt><code>guestfwd</code></dt>
      <dd>TCP traffic sent by the guest to a given IP address and port is
        forwarded to the channel device on the host. The <code>target</code>
        element must have <code>address</code> and <code>port</code> attributes.
        <span class="since">Since 0.7.3</span></dd>
7079 7080 7081

      <dt><code>virtio</code></dt>
      <dd>Paravirtualized virtio channel. Channel is exposed in the guest under
E
Eric Blake 已提交
7082
        /dev/vport*, and if the optional element <code>name</code> is specified,
7083
        /dev/virtio-ports/$name (for more info, please see
E
Eric Blake 已提交
7084 7085
        <a href="http://fedoraproject.org/wiki/Features/VirtioSerial">http://fedoraproject.org/wiki/Features/VirtioSerial</a>). The
        optional element <code>address</code> can tie the channel to a
7086 7087
        particular <code>type='virtio-serial'</code>
        controller, <a href="#elementsAddress">documented above</a>.
D
Daniel P. Berrange 已提交
7088 7089 7090 7091
        With qemu, if <code>name</code> is "org.qemu.guest_agent.0",
        then libvirt can interact with a guest agent installed in the
        guest, for actions such as guest shutdown or file system quiescing.
        <span class="since">Since 0.7.7, guest agent interaction
7092
        since 0.9.10</span> Moreover, <span class="since">since 1.0.6</span>
7093 7094 7095 7096
        it is possible to have source path auto generated for virtio unix channels.
        This is very useful in case of a qemu guest agent, where users don't
        usually care about the source path since it's libvirt who talks to
        the guest agent. In case users want to utilize this feature, they should
7097 7098 7099 7100 7101 7102
        leave <code>&lt;source&gt;</code> element out. <span class="since">Since
        1.2.11</span> the active XML for a virtio channel may contain an optional
        <code>state</code> attribute that reflects whether a process in the
        guest is active on the channel. This is an output-only attribute.
        Possible values for the <code>state</code> attribute are
        <code>connected</code> and <code>disconnected</code>.
7103
      </dd>
J
Joao Martins 已提交
7104 7105 7106 7107 7108 7109 7110 7111 7112 7113
      <dt><code>xen</code></dt>
      <dd> Paravirtualized Xen channel. Channel is exposed in the guest as a
        Xen console but identified with a name. Setup and consumption of a Xen
        channel depends on software and configuration in the guest
        (for more info, please see <a href="http://xenbits.xen.org/docs/unstable/misc/channel.txt">http://xenbits.xen.org/docs/unstable/misc/channel.txt</a>).
        Channel source path semantics are the same as the virtio target type.
        The <code>state</code> attribute is not supported since Xen channels
        lack the necessary probing mechanism.
        <span class="since">Since 2.3.0</span>
      </dd>
7114 7115 7116 7117 7118 7119 7120 7121 7122 7123 7124 7125 7126
      <dt><code>spicevmc</code></dt>
      <dd>Paravirtualized SPICE channel. The domain must also have a
        SPICE server as a <a href="#elementsGraphics">graphics
        device</a>, at which point the host piggy-backs messages
        across the <code>main</code> channel.  The <code>target</code>
        element must be present, with
        attribute <code>type='virtio'</code>; an optional
        attribute <code>name</code> controls how the guest will have
        access to the channel, and defaults
        to <code>name='com.redhat.spice.0'</code>.  The
        optional <code>address</code> element can tie the channel to a
        particular <code>type='virtio-serial'</code> controller.
        <span class="since">Since 0.8.8</span></dd>
7127 7128
    </dl>

7129
    <h5><a id="elementsCharHostInterface">Host interface</a></h5>
7130 7131 7132 7133 7134

    <p>
      A character device presents itself to the host as one of the following
      types.
    </p>
D
Daniel P. Berrange 已提交
7135

7136
    <h6><a id="elementsCharSTDIO">Domain logfile</a></h6>
D
Daniel P. Berrange 已提交
7137 7138 7139 7140 7141 7142

    <p>
      This disables all input on the character device, and sends output
      into the virtual machine's logfile
    </p>

7143
<pre>
7144 7145 7146 7147 7148 7149 7150
...
&lt;devices&gt;
  &lt;console type='stdio'&gt;
    &lt;target port='1'/&gt;
  &lt;/console&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
7151 7152


7153
    <h6><a id="elementsCharFle">Device logfile</a></h6>
D
Daniel P. Berrange 已提交
7154 7155 7156 7157 7158 7159

    <p>
      A file is opened and all data sent to the character
      device is written to the file.
    </p>

7160
<pre>
7161 7162 7163 7164 7165 7166 7167 7168
...
&lt;devices&gt;
  &lt;serial type="file"&gt;
    &lt;source path="/var/log/vm/vm-serial.log"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
7169

7170
    <h6><a id="elementsCharVC">Virtual console</a></h6>
D
Daniel P. Berrange 已提交
7171 7172 7173 7174 7175 7176 7177

    <p>
      Connects the character device to the graphical framebuffer in
      a virtual console. This is typically accessed via a special
      hotkey sequence such as "ctrl+alt+3"
    </p>

7178
<pre>
7179 7180 7181 7182 7183 7184 7185
...
&lt;devices&gt;
  &lt;serial type='vc'&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
7186

7187
    <h6><a id="elementsCharNull">Null device</a></h6>
D
Daniel P. Berrange 已提交
7188 7189 7190 7191 7192 7193

    <p>
      Connects the character device to the void. No data is ever
      provided to the input. All data written is discarded.
    </p>

7194
<pre>
7195 7196 7197 7198 7199 7200 7201
...
&lt;devices&gt;
  &lt;serial type='null'&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
7202

7203
    <h6><a id="elementsCharPTY">Pseudo TTY</a></h6>
D
Daniel P. Berrange 已提交
7204 7205 7206 7207 7208 7209 7210

    <p>
      A Pseudo TTY is allocated using /dev/ptmx. A suitable client
      such as 'virsh console' can connect to interact with the
      serial port locally.
    </p>

7211
<pre>
7212 7213 7214 7215 7216 7217 7218 7219
...
&lt;devices&gt;
  &lt;serial type="pty"&gt;
    &lt;source path="/dev/pts/3"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
7220 7221 7222

    <p>
      NB special case if &lt;console type='pty'&gt;, then the TTY
A
Atsushi SAKAI 已提交
7223
      path is also duplicated as an attribute tty='/dev/pts/3'
D
Daniel P. Berrange 已提交
7224 7225 7226 7227
      on the top level &lt;console&gt; tag. This provides compat
      with existing syntax for &lt;console&gt; tags.
    </p>

7228
    <h6><a id="elementsCharHost">Host device proxy</a></h6>
D
Daniel P. Berrange 已提交
7229 7230 7231 7232 7233

    <p>
      The character device is passed through to the underlying
      physical character device. The device types must match,
      eg the emulated serial port should only be connected to
A
Atsushi SAKAI 已提交
7234
      a host serial port - don't connect a serial port to a parallel
D
Daniel P. Berrange 已提交
7235 7236 7237
      port.
    </p>

7238
<pre>
7239 7240 7241 7242 7243 7244 7245 7246
...
&lt;devices&gt;
  &lt;serial type="dev"&gt;
    &lt;source path="/dev/ttyS0"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
7247

7248
    <h6><a id="elementsCharPipe">Named pipe</a></h6>
7249 7250 7251 7252 7253 7254

    <p>
      The character device writes output to a named pipe. See pipe(7) for
      more info.
    </p>

7255
<pre>
7256 7257 7258 7259 7260 7261 7262 7263
...
&lt;devices&gt;
  &lt;serial type="pipe"&gt;
    &lt;source path="/tmp/mypipe"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
7264

7265
    <h6><a id="elementsCharTCP">TCP client/server</a></h6>
D
Daniel P. Berrange 已提交
7266 7267 7268

    <p>
      The character device acts as a TCP client connecting to a
7269
      remote server.
D
Daniel P. Berrange 已提交
7270 7271
    </p>

7272
<pre>
7273 7274 7275 7276 7277 7278 7279 7280 7281
...
&lt;devices&gt;
  &lt;serial type="tcp"&gt;
    &lt;source mode="connect" host="0.0.0.0" service="2445"/&gt;
    &lt;protocol type="raw"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
 ...</pre>
7282 7283 7284 7285 7286

    <p>
      Or as a TCP server waiting for a client connection.
    </p>

7287
<pre>
7288 7289 7290 7291 7292 7293 7294 7295 7296
...
&lt;devices&gt;
  &lt;serial type="tcp"&gt;
    &lt;source mode="bind" host="127.0.0.1" service="2445"/&gt;
    &lt;protocol type="raw"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
7297 7298

    <p>
E
Eric Blake 已提交
7299
      Alternatively you can use <code>telnet</code> instead
J
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7300 7301 7302 7303 7304 7305 7306
      of <code>raw</code> TCP in order to utilize the telnet protocol
      for the connection.
    </p>
    <p>
      <span class="since">Since 0.8.5,</span> some hypervisors support
      use of either <code>telnets</code> (secure telnet) or <code>tls</code>
      (via secure sockets layer) as the transport protocol for connections.
E
Eric Blake 已提交
7307
    </p>
7308

7309
<pre>
7310 7311 7312 7313 7314 7315 7316
...
&lt;devices&gt;
  &lt;serial type="tcp"&gt;
    &lt;source mode="connect" host="0.0.0.0" service="2445"/&gt;
    &lt;protocol type="telnet"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
7317
  ...
7318 7319 7320 7321 7322 7323 7324
  &lt;serial type="tcp"&gt;
    &lt;source mode="bind" host="127.0.0.1" service="2445"/&gt;
    &lt;protocol type="telnet"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
7325 7326 7327 7328 7329 7330 7331 7332 7333 7334 7335 7336 7337 7338 7339 7340 7341 7342 7343

    <p>
      <span class="since">Since 2.4.0,</span> the optional attribute
      <code>tls</code> can be used to control whether a chardev
      TCP communication channel would utilize a hypervisor configured
      TLS X.509 certificate environment in order to encrypt the data
      channel. For the QEMU hypervisor, usage of a TLS environment can
      be controlled on the host by the <code>chardev_tls</code> and
      <code>chardev_tls_x509_cert_dir</code> or
      <code>default_tls_x509_cert_dir</code> settings in the file
      /etc/libvirt/qemu.conf. If <code>chardev_tls</code> is enabled,
      then unless the <code>tls</code> attribute is set to "no", libvirt
      will use the host configured TLS environment.
      If <code>chardev_tls</code> is disabled, but the <code>tls</code>
      attribute is set to "yes", then libvirt will attempt to use the
      host TLS environment if either the <code>chardev_tls_x509_cert_dir</code>
      or <code>default_tls_x509_cert_dir</code> TLS directory structure exists.
    </p>
<pre>
7344 7345 7346 7347 7348 7349 7350 7351 7352
...
&lt;devices&gt;
  &lt;serial type="tcp"&gt;
    &lt;source mode='connect' host="127.0.0.1" service="5555" tls="yes"/&gt;
    &lt;protocol type="raw"/&gt;
    &lt;target port="0"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
7353

7354
    <h6><a id="elementsCharUDP">UDP network console</a></h6>
D
Daniel P. Berrange 已提交
7355 7356 7357 7358 7359 7360

    <p>
      The character device acts as a UDP netconsole service,
      sending and receiving packets. This is a lossy service.
    </p>

7361
<pre>
7362 7363 7364 7365 7366 7367 7368 7369 7370
...
&lt;devices&gt;
  &lt;serial type="udp"&gt;
    &lt;source mode="bind" host="0.0.0.0" service="2445"/&gt;
    &lt;source mode="connect" host="0.0.0.0" service="2445"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
7371

7372
    <h6><a id="elementsCharUNIX">UNIX domain socket client/server</a></h6>
D
Daniel P. Berrange 已提交
7373 7374 7375 7376 7377 7378

    <p>
      The character device acts as a UNIX domain socket server,
      accepting connections from local clients.
    </p>

7379
<pre>
7380 7381 7382 7383 7384 7385 7386 7387
...
&lt;devices&gt;
  &lt;serial type="unix"&gt;
    &lt;source mode="bind" path="/tmp/foo"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
D
Daniel P. Berrange 已提交
7388

7389
    <h6><a id="elementsCharSpiceport">Spice channel</a></h6>
7390 7391 7392 7393 7394 7395

    <p>
      The character device is accessible through spice connection
      under a channel name specified in the <code>channel</code>
      attribute.  <span class="since">Since 1.2.2</span>
    </p>
7396 7397 7398 7399 7400
    <p>
      Note: depending on the hypervisor, spiceports might (or might not)
      be enabled on domains with or without <a href="#elementsGraphics">spice
      graphics</a>.
    </p>
7401 7402

<pre>
7403 7404 7405 7406 7407 7408 7409 7410
...
&lt;devices&gt;
  &lt;serial type="spiceport"&gt;
    &lt;source channel="org.qemu.console.serial.0"/&gt;
    &lt;target port="1"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
7411

7412
    <h6><a id="elementsNmdm">Nmdm device</a></h6>
7413 7414 7415

    <p>
      The nmdm device driver, available on FreeBSD, provides two
C
Chen Hanxiao 已提交
7416
      tty devices connected together by a virtual null modem cable.
7417 7418 7419 7420
      <span class="since">Since 1.2.4</span>
    </p>

<pre>
7421 7422 7423 7424 7425 7426 7427
...
&lt;devices&gt;
  &lt;serial type="nmdm"&gt;
    &lt;source master="/dev/nmdm0A" slave="/dev/nmdm0B"/&gt;
  &lt;/serial&gt;
&lt;/devices&gt;
...</pre>
7428 7429 7430 7431 7432 7433 7434

    <p>
      The <code>source</code> element has these attributes:
    </p>

    <dl>
      <dt><code>master</code></dt>
7435 7436
      <dd>Master device of the pair, that is passed to the hypervisor.
      Device is specified by a fully qualified path.</dd>
7437 7438 7439

      <dt><code>slave</code></dt>
      <dd>Slave device of the pair, that is passed to the clients for connection
7440
      to the guest console. Device is specified by a fully qualified path.</dd>
7441
    </dl>
7442

7443
    <h4><a id="elementsSound">Sound devices</a></h4>
7444 7445 7446 7447 7448 7449

    <p>
      A virtual sound card can be attached to the host via the
      <code>sound</code> element. <span class="since">Since 0.4.3</span>
    </p>

7450
<pre>
7451 7452 7453 7454 7455
...
&lt;devices&gt;
  &lt;sound model='es1370'/&gt;
&lt;/devices&gt;
...</pre>
7456 7457 7458 7459 7460 7461 7462

    <dl>
      <dt><code>sound</code></dt>
      <dd>
        The <code>sound</code> element has one mandatory attribute,
        <code>model</code>, which specifies what real sound device is emulated.
        Valid values are specific to the underlying hypervisor, though typical
7463
        choices are 'es1370', 'sb16', 'ac97', 'ich6' and 'usb'.
7464
        (<span class="since">
7465 7466
         'ac97' only since 0.6.0, 'ich6' only since 0.8.8,
         'usb' only since 1.2.7</span>)
7467 7468 7469
      </dd>
    </dl>

7470 7471 7472 7473 7474
    <p>
      <span class="since">Since 0.9.13</span>, a sound element
      with <code>ich6</code> model can have optional
      sub-elements <code>&lt;codec&gt;</code> to attach various audio
      codecs to the audio device. If not specified, a default codec
F
Filip Alac 已提交
7475 7476 7477 7478 7479 7480 7481 7482 7483 7484 7485 7486
      will be attached to allow playback and recording.
      </p>
      <p>
      Valid values are:
      </p>
      <p>
      <ul>
        <li>'duplex' - advertise a line-in and a line-out </li>
        <li>'micro' -  advertise a speaker and a microphone </li>
        <li>'output' - advertise a line-out
            <span class="since">Since 4.4.0</span></li>
      </ul>
7487 7488 7489
    </p>

<pre>
7490 7491 7492 7493 7494 7495 7496
...
&lt;devices&gt;
  &lt;sound model='ich6'&gt;
    &lt;codec type='micro'/&gt;
  &lt;/sound&gt;
&lt;/devices&gt;
...</pre>
7497

E
Eric Blake 已提交
7498 7499 7500
    <p>
      Each <code>sound</code> element has an optional
      sub-element <code>&lt;address&gt;</code> which can tie the
7501 7502
      device to a particular PCI
      slot, <a href="#elementsAddress">documented above</a>.
E
Eric Blake 已提交
7503 7504
    </p>

7505
    <h4><a id="elementsWatchdog">Watchdog device</a></h4>
R
Richard Jones 已提交
7506 7507 7508 7509 7510 7511 7512 7513 7514 7515 7516 7517 7518 7519 7520 7521 7522 7523 7524

    <p>
      A virtual hardware watchdog device can be added to the guest via
      the <code>watchdog</code> element.
      <span class="since">Since 0.7.3, QEMU and KVM only</span>
    </p>

    <p>
      The watchdog device requires an additional driver and management
      daemon in the guest.  Just enabling the watchdog in the libvirt
      configuration does not do anything useful on its own.
    </p>

    <p>
      Currently libvirt does not support notification when the
      watchdog fires.  This feature is planned for a future version of
      libvirt.
    </p>

7525
<pre>
7526 7527 7528 7529 7530
...
&lt;devices&gt;
  &lt;watchdog model='i6300esb'/&gt;
&lt;/devices&gt;
...</pre>
R
Richard Jones 已提交
7531

7532 7533 7534 7535 7536 7537
<pre>
  ...
  &lt;devices&gt;
    &lt;watchdog model='i6300esb' action='poweroff'/&gt;
  &lt;/devices&gt;
&lt;/domain&gt;</pre>
R
Richard Jones 已提交
7538 7539 7540 7541

    <dl>
      <dt><code>model</code></dt>
      <dd>
M
Matthew Booth 已提交
7542
        <p>
R
Richard Jones 已提交
7543
        The required <code>model</code> attribute specifies what real
M
Matthew Booth 已提交
7544 7545 7546 7547 7548 7549 7550
        watchdog device is emulated.  Valid values are specific to the
        underlying hypervisor.
        </p>
        <p>
        QEMU and KVM support:
        </p>
        <ul>
7551
          <li>'i6300esb' - the recommended device,
M
Matthew Booth 已提交
7552
            emulating a PCI Intel 6300ESB </li>
7553 7554
          <li>'ib700' - emulating an ISA iBase IB700 </li>
          <li>'diag288' - emulating an S390 DIAG288 device
7555
            <span class="since">Since 1.2.17</span></li>
M
Matthew Booth 已提交
7556
        </ul>
R
Richard Jones 已提交
7557 7558 7559
      </dd>
      <dt><code>action</code></dt>
      <dd>
M
Matthew Booth 已提交
7560
        <p>
R
Richard Jones 已提交
7561
        The optional <code>action</code> attribute describes what
M
Matthew Booth 已提交
7562 7563 7564 7565 7566 7567 7568
        action to take when the watchdog expires.  Valid values are
        specific to the underlying hypervisor.
        </p>
        <p>
        QEMU and KVM support:
        </p>
        <ul>
7569 7570
          <li>'reset' - default, forcefully reset the guest</li>
          <li>'shutdown' - gracefully shutdown the guest
M
Matthew Booth 已提交
7571
            (not recommended) </li>
7572 7573 7574 7575
          <li>'poweroff' - forcefully power off the guest</li>
          <li>'pause' - pause the guest</li>
          <li>'none' - do nothing</li>
          <li>'dump' - automatically dump the guest
7576
            <span class="since">Since 0.8.7</span></li>
7577
          <li>'inject-nmi' - inject a non-maskable interrupt
7578
            into the guest
7579
            <span class="since">Since 1.2.17</span></li>
M
Matthew Booth 已提交
7580 7581
        </ul>
        <p>
7582
        Note 1: the 'shutdown' action requires that the guest
M
Matthew Booth 已提交
7583 7584 7585 7586 7587
        is responsive to ACPI signals.  In the sort of situations
        where the watchdog has expired, guests are usually unable
        to respond to ACPI signals.  Therefore using 'shutdown'
        is not recommended.
        </p>
7588 7589 7590 7591
        <p>
        Note 2: the directory to save dump files can be configured
        by <code>auto_dump_path</code> in file /etc/libvirt/qemu.conf.
        </p>
R
Richard Jones 已提交
7592 7593 7594
      </dd>
    </dl>

7595
    <h4><a id="elementsMemBalloon">Memory balloon device</a></h4>
7596 7597 7598 7599 7600 7601 7602 7603

    <p>
      A virtual memory balloon device is added to all Xen and KVM/QEMU
      guests. It will be seen as <code>memballoon</code> element.
      It will be automatically added when appropriate, so there is no
      need to explicitly add this element in the guest XML unless a
      specific PCI slot needs to be assigned.
      <span class="since">Since 0.8.3, Xen, QEMU and KVM only</span>
7604 7605 7606
      Additionally, <span class="since">since 0.8.4</span>, if the
      memballoon device needs to be explicitly disabled,
      <code>model='none'</code> may be used.
7607 7608 7609
    </p>

    <p>
J
Ján Tomko 已提交
7610
      Example: automatically added device with KVM
7611 7612
    </p>
<pre>
7613 7614 7615 7616 7617
...
&lt;devices&gt;
  &lt;memballoon model='virtio'/&gt;
&lt;/devices&gt;
...</pre>
7618 7619

    <p>
J
Ján Tomko 已提交
7620
      Example: manually added device with static PCI slot 2 requested
7621 7622 7623 7624
    </p>
<pre>
  ...
  &lt;devices&gt;
J
Ján Tomko 已提交
7625 7626
    &lt;memballoon model='virtio'&gt;
      &lt;address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/&gt;
7627
      &lt;stats period='10'/&gt;
7628
      &lt;driver iommu='on' ats='on'/&gt;
J
Ján Tomko 已提交
7629
    &lt;/memballoon&gt;
7630 7631 7632 7633 7634 7635 7636 7637
  &lt;/devices&gt;
&lt;/domain&gt;</pre>

    <dl>
      <dt><code>model</code></dt>
      <dd>
        <p>
          The required <code>model</code> attribute specifies what type
E
Eric Blake 已提交
7638 7639
          of balloon device is provided. Valid values are specific to
          the virtualization platform
7640 7641
        </p>
        <ul>
7642 7643
          <li>'virtio' - default with QEMU/KVM</li>
          <li>'xen' - default with Xen</li>
7644 7645
        </ul>
      </dd>
7646 7647 7648 7649 7650 7651 7652 7653 7654 7655
      <dt><code>autodeflate</code></dt>
      <dd>
        <p>
          The optional <code>autodeflate</code> attribute allows to
          enable/disable (values "on"/"off", respectively) the ability of the
          QEMU virtio memory balloon to release some memory at the last moment
          before a guest's process get killed by Out of Memory killer.
          <span class="since">Since 1.3.1, QEMU and KVM only</span>
        </p>
      </dd>
7656 7657 7658
      <dt><code>period</code></dt>
      <dd>
        <p>
7659 7660 7661 7662 7663 7664 7665 7666 7667 7668 7669
          The optional <code>period</code> allows the QEMU virtio memory balloon
          driver to provide statistics through the <code>virsh dommemstat
          [domain]</code> command. By default, collection is not enabled. In
          order to enable, use the <code>virsh dommemstat [domain] --period
          [number]</code> command or <code>virsh edit</code> command to add the
          option to the XML definition.  The <code>virsh dommemstat</code> will
          accept the options <code>--live</code>, <code>--current</code>,
          or <code>--config</code>.  If an option is not provided, the change
          for a running domain will only be made to the active guest.  If the
          QEMU driver is not at the right revision, the attempt to set the
          period will fail.  Large values (e.g. many years) might be ignored.
7670 7671 7672
          <span class='since'>Since 1.1.1, requires QEMU 1.5</span>
        </p>
      </dd>
7673 7674 7675 7676 7677 7678
      <dt><code>driver</code></dt>
      <dd>
        For model <code>virtio</code> memballoon,
        <a href="#elementsVirtio">Virtio-specific options</a> can also be
        set. (<span class="since">Since 3.5.0</span>)
      </dd>
7679
    </dl>
7680
    <h4><a id="elementsRng">Random number generator device</a></h4>
7681 7682 7683 7684 7685 7686 7687 7688 7689 7690 7691

    <p>
      The virtual random number generator device allows the host to pass
      through entropy to guest operating systems.
      <span class="since">Since 1.0.3</span>
    </p>

    <p>
      Example: usage of the RNG device:
    </p>
<pre>
7692 7693 7694 7695 7696 7697 7698 7699 7700 7701 7702 7703 7704
...
&lt;devices&gt;
  &lt;rng model='virtio'&gt;
    &lt;rate period="2000" bytes="1234"/&gt;
    &lt;backend model='random'&gt;/dev/random&lt;/backend&gt;
    &lt;!-- OR --&gt;
    &lt;backend model='egd' type='udp'&gt;
      &lt;source mode='bind' service='1234'/&gt;
      &lt;source mode='connect' host='1.2.3.4' service='1234'/&gt;
    &lt;/backend&gt;
  &lt;/rng&gt;
&lt;/devices&gt;
...
7705 7706 7707 7708 7709 7710 7711 7712 7713 7714
</pre>
    <dl>
      <dt><code>model</code></dt>
      <dd>
        <p>
          The required <code>model</code> attribute specifies what type
          of RNG device is provided. Valid values are specific to
          the virtualization platform:
        </p>
        <ul>
7715
          <li>'virtio' - supported by qemu and virtio-rng kernel module</li>
7716 7717
        </ul>
      </dd>
7718 7719 7720 7721 7722 7723 7724 7725 7726 7727 7728 7729
      <dt><code>rate</code></dt>
      <dd>
        <p>
          The optional <code>rate</code> element allows limiting the rate at
          which entropy can be consumed from the source.  The mandatory
          attribute <code>bytes</code> specifies how many bytes are permitted
          to be consumed per period.  An optional <code>period</code> attribute
          specifies the duration of a period in milliseconds; if omitted, the
          period is taken as 1000 milliseconds (1 second).
          <span class='since'>Since 1.0.4</span>
        </p>
      </dd>
7730 7731 7732 7733 7734 7735 7736
      <dt><code>backend</code></dt>
      <dd>
        <p>
          The <code>backend</code> element specifies the source of entropy
          to be used for the domain. The source model is configured using the
          <code>model</code> attribute. Supported source models are:
        </p>
7737 7738 7739 7740
        <dl>
          <dt><code>random</code></dt>
          <dd>
            <p>
7741 7742 7743 7744 7745 7746 7747 7748 7749 7750
              This backend type expects a non-blocking character device
              as input. The file name is specified as contents of the
              <code>backend</code> element. <span class='since'>Since
              1.3.4</span> any path is accepted. Before that
              <code>/dev/random</code> and <code>/dev/hwrng</code> were
              the only accepted paths. When no file name is specified,
              the hypervisor default is used. For QEMU, the default is
              <code>/dev/random</code>. However, the recommended source
              of entropy is <code>/dev/urandom</code> (as it doesn't
              have the limitations of <code>/dev/random</code>).
7751 7752 7753 7754 7755 7756 7757 7758 7759 7760 7761 7762
            </p>
          </dd>
          <dt><code>egd</code></dt>
          <dd>
            <p>
              This backend connects to a source using the EGD protocol.
              The source is specified as a character device. Refer to
              <a href='#elementsCharHostInterface'>character device host interface</a>
              for more information.
            </p>
          </dd>
        </dl>
7763
      </dd>
7764 7765 7766 7767 7768 7769 7770 7771 7772 7773 7774
      <dt><code>driver</code></dt>
      <dd>
        The subelement <code>driver</code> can be used to tune the device:
        <dl>
          <dt>virtio options</dt>
          <dd>
          <a href="#elementsVirtio">Virtio-specific options</a> can also be
          set. (<span class="since">Since 3.5.0</span>)
          </dd>
        </dl>
      </dd>
7775 7776

    </dl>
7777

7778
    <h4><a id="elementsTpm">TPM device</a></h4>
7779 7780 7781

    <p>
      The TPM device enables a QEMU guest to have access to TPM
7782
      functionality. The TPM device may either be a TPM 1.2 or
7783
      a TPM 2.0.
7784 7785 7786
    </p>
    <p>
      The TPM passthrough device type provides access to the host's TPM
7787
      for one QEMU guest. No other software may be using the TPM device,
7788 7789 7790 7791 7792 7793 7794 7795
      typically /dev/tpm0, at the time the QEMU guest is started.
      <span class="since">'passthrough' since 1.0.5</span>
    </p>

    <p>
     Example: usage of the TPM passthrough device
    </p>
<pre>
7796 7797 7798 7799 7800 7801 7802 7803 7804
...
&lt;devices&gt;
  &lt;tpm model='tpm-tis'&gt;
    &lt;backend type='passthrough'&gt;
      &lt;device path='/dev/tpm0'/&gt;
    &lt;/backend&gt;
  &lt;/tpm&gt;
&lt;/devices&gt;
...
7805 7806 7807 7808 7809 7810 7811 7812 7813 7814 7815 7816 7817 7818 7819
</pre>

    <p>
      The emulator device type gives access to a TPM emulator providing
      TPM functionality for each VM. QEMU talks to it over a Unix socket. With
      the emulator device type each guest gets its own private TPM.
      <span class="since">'emulator' since 4.5.0</span>
    </p>
    <p>
     Example: usage of the TPM Emulator
    </p>
<pre>
  ...
  &lt;devices&gt;
    &lt;tpm model='tpm-tis'&gt;
7820
      &lt;backend type='emulator' version='2.0'&gt;
7821 7822 7823 7824
      &lt;/backend&gt;
    &lt;/tpm&gt;
  &lt;/devices&gt;
  ...
7825 7826 7827 7828 7829 7830 7831 7832
</pre>
    <dl>
      <dt><code>model</code></dt>
      <dd>
        <p>
          The <code>model</code> attribute specifies what device
          model QEMU provides to the guest. If no model name is provided,
          <code>tpm-tis</code> will automatically be chosen.
7833 7834
          <span class="since">Since 4.4.0</span>, another available choice
          is the <code>tpm-crb</code>, which should only be used when the
7835
          backend device is a TPM 2.0.
7836 7837 7838 7839 7840 7841 7842 7843
        </p>
      </dd>
      <dt><code>backend</code></dt>
      <dd>
        <p>
          The <code>backend</code> element specifies the type of
          TPM device. The following types are supported:
        </p>
7844 7845 7846 7847 7848 7849 7850 7851 7852 7853 7854 7855 7856 7857 7858
        <dl>
          <dt><code>passthrough</code></dt>
          <dd>
            <p>
              Use the host's TPM device.
            </p>
            <p>
              This backend type requires exclusive access to a TPM device on
              the host. An example for such a device is /dev/tpm0. The fully
              qualified file name is specified by path attribute of the
              <code>source</code> element. If no file name is specified then
              /dev/tpm0 is automatically used.
            </p>
          </dd>
        </dl>
7859 7860 7861 7862 7863 7864 7865 7866 7867 7868
        <dl>
          <dt><code>emulator</code></dt>
          <dd>
            <p>
              For this backend type the 'swtpm' TPM Emulator must be installed on the
              host. Libvirt will automatically start an independent TPM emulator
              for each QEMU guest requesting access to it.
            </p>
          </dd>
        </dl>
7869
      </dd>
7870 7871 7872 7873 7874 7875 7876 7877 7878 7879 7880 7881 7882
      <dt><code>version</code></dt>
      <dd>
        <p>
          The <code>version</code> attribute indicates the version
          of the TPM. By default a TPM 1.2 is created. This attribute
          only works with the <code>emulator</code> backend. The following
          versions are supported:
        </p>
        <ul>
          <li>'1.2' : creates a TPM 1.2</li>
          <li>'2.0' : creates a TPM 2.0</li>
        </ul>
      </dd>
7883 7884
    </dl>

7885
    <h4><a id="elementsNVRAM">NVRAM device</a></h4>
L
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    <p>
      nvram device is always added to pSeries guest on PPC64, and its address
      is allowed to be changed.  Element <code>nvram</code> (only valid for
      pSeries guest, <span class="since">since 1.0.5</span>) is provided to
      enable the address setting.
    </p>
    <p>
      Example: usage of NVRAM configuration
    </p>
<pre>
7896 7897 7898 7899 7900 7901 7902
...
&lt;devices&gt;
  &lt;nvram&gt;
    &lt;address type='spapr-vio' reg='0x3000'/&gt;
  &lt;/nvram&gt;
&lt;/devices&gt;
...
L
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</pre>
  <dl>
    <dt><code>spapr-vio</code></dt>
    <dd>
      <p>
        VIO device address type, only valid for PPC64.
      </p>
    </dd>
    <dt><code>reg</code></dt>
    <dd>
      <p>
        Device address
      </p>
    </dd>
  </dl>

7919
    <h4><a id="elementsPanic">panic device</a></h4>
H
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7920 7921 7922 7923 7924
    <p>
      panic device enables libvirt to receive panic notification from a QEMU
      guest.
      <span class="since">Since 1.2.1, QEMU and KVM only</span>
    </p>
7925
    <p>
7926 7927 7928 7929 7930 7931 7932 7933 7934
      This feature is always enabled for:
    </p>
    <ul>
      <li>pSeries guests, since it's implemented by the guest firmware</li>
      <li>S390 guests, since it's an integral part of the S390 architecture</li>
    </ul>
    <p>
      For the guest types listed above, libvirt automatically adds a
      <code>panic</code> element to the domain XML.
7935
    </p>
H
Hu Tao 已提交
7936 7937 7938 7939
    <p>
      Example: usage of panic configuration
    </p>
<pre>
7940 7941 7942 7943 7944 7945 7946 7947
...
&lt;devices&gt;
  &lt;panic model='hyperv'/&gt;
  &lt;panic model='isa'&gt;
    &lt;address type='isa' iobase='0x505'/&gt;
  &lt;/panic&gt;
&lt;/devices&gt;
...
H
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7948 7949
</pre>
  <dl>
7950 7951 7952 7953 7954 7955 7956 7957
    <dt><code>model</code></dt>
      <dd>
        <p>
          The optional <code>model</code> attribute specifies what type
          of panic device is provided. The panic model used when this attribute
          is missing depends on the hypervisor and guest arch.
        </p>
        <ul>
7958 7959 7960
          <li>'isa' - for ISA pvpanic device</li>
          <li>'pseries' - default and valid only for pSeries guests.</li>
          <li>'hyperv' - for Hyper-V crash CPU feature.
7961
            <span class="since">Since 1.3.0, QEMU and KVM only</span></li>
7962
          <li>'s390' - default for S390 guests.
7963
            <span class="since">Since 1.3.5</span></li>
7964 7965
        </ul>
      </dd>
H
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7966 7967 7968 7969
    <dt><code>address</code></dt>
    <dd>
      <p>
        address of panic. The default ioport is 0x505. Most users
7970
        don't need to specify an address, and doing so is forbidden
7971
        altogether for s390, pseries and hyperv models.
H
Hu Tao 已提交
7972 7973 7974 7975
      </p>
    </dd>
  </dl>

7976
  <h4><a id="elementsShmem">Shared memory device</a></h4>
7977 7978 7979 7980

    <p>
      A shared memory device allows to share a memory region between
      different virtual machines and the host.
M
Martin Kletzander 已提交
7981
      <span class="since">Since 1.2.10, QEMU and KVM only</span>
7982 7983 7984
    </p>

<pre>
7985 7986 7987 7988 7989 7990 7991 7992 7993 7994 7995 7996 7997 7998
...
&lt;devices&gt;
  &lt;shmem name='my_shmem0'&gt;
    &lt;model type='ivshmem-plain'/&gt;
    &lt;size unit='M'&gt;4&lt;/size&gt;
  &lt;/shmem&gt;
  &lt;shmem name='shmem_server'&gt;
    &lt;model type='ivshmem-doorbell'/&gt;
    &lt;size unit='M'&gt;2&lt;/size&gt;
    &lt;server path='/tmp/socket-shmem'/&gt;
    &lt;msi vectors='32' ioeventfd='on'/&gt;
  &lt;/shmem&gt;
&lt;/devices&gt;
...
7999 8000 8001 8002 8003 8004 8005 8006
</pre>

  <dl>
    <dt><code>shmem</code></dt>
    <dd>
      The <code>shmem</code> element has one mandatory attribute,
      <code>name</code> to identify the shared memory.
    </dd>
8007 8008 8009 8010
    <dt><code>model</code></dt>
    <dd>
      Attribute <code>type</code> of the optional element <code>model</code>
      specifies the model of the underlying device providing the
8011 8012 8013 8014 8015
      <code>shmem</code> device.  The models currently supported are
      <code>ivshmem</code> (supports both server and server-less shmem, but is
      deprecated by newer QEMU in favour of the -plain and -doorbell variants),
      <code>ivshmem-plain</code> (only for server-less shmem) and
      <code>ivshmem-doorbell</code> (only for shmem with the server).
8016
    </dd>
8017 8018 8019 8020 8021 8022 8023 8024 8025
    <dt><code>size</code></dt>
    <dd>
      The optional <code>size</code> element specifies the size of the shared
      memory. This must be power of 2 and greater than or equal to 1 MiB.
    </dd>
    <dt><code>server</code></dt>
    <dd>
      The optional <code>server</code> element can be used to configure a server
      socket the device is supposed to connect to.  The optional
8026 8027
      <code>path</code> attribute specifies the absolute path to the unix socket
      and defaults to <code>/var/lib/libvirt/shmem/$shmem-$name-sock</code>.
8028 8029 8030 8031 8032 8033 8034 8035 8036 8037 8038 8039
    </dd>
    <dt><code>msi</code></dt>
    <dd>
      The optional <code>msi</code> element enables/disables (values "on"/"off",
      respectively) MSI interrupts. This option can currently be used only
      together with the <code>server</code> element. The <code>vectors</code>
      attribute can be used to specify the number of interrupt
      vectors. The <code>ioeventd</code> attribute enables/disables (values
      "on"/"off", respectively) ioeventfd.
    </dd>
  </dl>

8040
    <h4><a id="elementsMemory">Memory devices</a></h4>
8041 8042 8043 8044 8045 8046 8047 8048 8049 8050 8051 8052 8053 8054 8055 8056

    <p>
        In addition to the initial memory assigned to the guest, memory devices
        allow additional memory to be assigned to the guest in the form of
        memory modules.

        A memory device can be hot-plugged or hot-unplugged depending on the
        guests' memory resource needs.

        Some hypervisors may require NUMA configured for the guest.
    </p>

    <p>
      Example: usage of the memory devices
    </p>
<pre>
8057 8058
...
&lt;devices&gt;
8059
  &lt;memory model='dimm' access='private' discard='yes'&gt;
8060 8061 8062 8063 8064 8065 8066 8067 8068 8069 8070 8071 8072 8073 8074
    &lt;target&gt;
      &lt;size unit='KiB'&gt;524287&lt;/size&gt;
      &lt;node&gt;0&lt;/node&gt;
    &lt;/target&gt;
  &lt;/memory&gt;
  &lt;memory model='dimm'&gt;
    &lt;source&gt;
      &lt;pagesize unit='KiB'&gt;4096&lt;/pagesize&gt;
      &lt;nodemask&gt;1-3&lt;/nodemask&gt;
    &lt;/source&gt;
    &lt;target&gt;
      &lt;size unit='KiB'&gt;524287&lt;/size&gt;
      &lt;node&gt;1&lt;/node&gt;
    &lt;/target&gt;
  &lt;/memory&gt;
M
Michal Privoznik 已提交
8075 8076 8077 8078 8079 8080 8081
  &lt;memory model='nvdimm'&gt;
    &lt;source&gt;
      &lt;path&gt;/tmp/nvdimm&lt;/path&gt;
    &lt;/source&gt;
    &lt;target&gt;
      &lt;size unit='KiB'&gt;524288&lt;/size&gt;
      &lt;node&gt;1&lt;/node&gt;
8082 8083 8084
      &lt;label&gt;
        &lt;size unit='KiB'&gt;128&lt;/size&gt;
      &lt;/label&gt;
M
Michal Privoznik 已提交
8085 8086
    &lt;/target&gt;
  &lt;/memory&gt;
8087 8088
&lt;/devices&gt;
...
8089 8090 8091 8092 8093
</pre>
    <dl>
      <dt><code>model</code></dt>
      <dd>
        <p>
M
Michal Privoznik 已提交
8094 8095 8096 8097
          Provide <code>dimm</code> to add a virtual DIMM module to the guest.
          <span class="since">Since 1.2.14</span>
          Provide <code>nvdimm</code> model adds a Non-Volatile DIMM
          module. <span class="since">Since 3.2.0</span>
8098 8099 8100
        </p>
      </dd>

8101 8102 8103 8104 8105 8106 8107 8108 8109 8110 8111 8112
      <dt><code>access</code></dt>
      <dd>
        <p>
          An optional attribute <code>access</code>
          (<span class="since">since 3.2.0</span>) that provides
          capability to fine tune mapping of the memory on per
          module basis. Values are the same as
          <a href="#elementsMemoryBacking">Memory Backing</a>:
          <code>shared</code> and <code>private</code>.
        </p>
      </dd>

8113 8114 8115 8116 8117 8118 8119 8120 8121 8122 8123 8124 8125 8126
      <dt><code>discard</code></dt>
      <dd>
        <p>
          An optional attribute <code>discard</code>
          (<span class="since">since 4.4.0</span>) that provides
          capability to fine tune discard of data on per module
          basis. Accepted values are <code>yes</code> and
          <code>no</code>. The feature is described here:
          <a href="#elementsMemoryBacking">Memory Backing</a>.
          This attribute is allowed only for
          <code>model='dimm'</code>.
        </p>
      </dd>

8127 8128 8129
      <dt><code>source</code></dt>
      <dd>
        <p>
M
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8130 8131 8132 8133 8134
          For model <code>dimm</code> this element is optional and allows to
          fine tune the source of the memory used for the given memory device.
          If the element is not provided defaults configured via
          <code>numatune</code> are used. If <code>dimm</code> is provided,
          then the following optional elements can be provided as well:
8135 8136
        </p>

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8137 8138 8139 8140 8141 8142 8143 8144 8145 8146 8147 8148 8149 8150 8151 8152 8153 8154 8155 8156 8157
        <dl>
          <dt><code>pagesize</code></dt>
          <dd>
            <p>
              This element can be used to override the default
              host page size used for backing the memory device.
              The configured value must correspond to a page size
              supported by the host.
            </p>
          </dd>

          <dt><code>nodemask</code></dt>
          <dd>
            <p>
              This element can be used to override the default
              set of NUMA nodes where the memory would be
              allocated.
            </p>
          </dd>
        </dl>

8158
        <p>
M
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8159 8160 8161
          For model <code>nvdimm</code> this element is mandatory and has a
          single child element <code>path</code> that represents a path
          in the host that backs the nvdimm module in the guest.
8162 8163 8164 8165 8166 8167 8168 8169 8170 8171 8172 8173 8174 8175
        </p>
      </dd>

      <dt><code>target</code></dt>
      <dd>
        <p>
          The mandatory <code>target</code> element configures the placement and
          sizing of the added memory from the perspective of the guest.
        </p>
        <p>
          The mandatory <code>size</code> subelement configures the size of the
          added memory as a scaled integer.
        </p>
        <p>
8176 8177 8178
          The <code>node</code> subelement configures the guest NUMA node to
          attach the memory to. The element shall be used only if the guest has
          NUMA nodes configured.
8179
        </p>
8180 8181 8182 8183 8184 8185 8186 8187 8188 8189 8190 8191 8192 8193
        <p>
          For NVDIMM type devices one can optionally use
          <code>label</code> and its subelement <code>size</code>
          to configure the size of namespaces label storage
          within the NVDIMM module. The <code>size</code> element
          has usual meaning described
          <a href="#elementsMemoryAllocation">here</a>.
          For QEMU domains the following restrictions apply:
        </p>
        <ol>
          <li>the minimum label size is 128KiB,</li>
          <li>the remaining size (total-size - label-size) has to be aligned to
            4KiB</li>
        </ol>
8194 8195 8196
      </dd>
    </dl>

8197
    <h4><a id="elementsIommu">IOMMU devices</a></h4>
J
Ján Tomko 已提交
8198 8199 8200 8201 8202 8203 8204 8205 8206 8207

    <p>
      The <code>iommu</code> element can be used to add an IOMMU device.
      <span class="since">Since 2.1.0</span>
    </p>

    <p>
      Example:
    </p>
<pre>
8208 8209
...
&lt;devices&gt;
8210 8211 8212
  &lt;iommu model='intel'&gt;
    &lt;driver intremap='on'/&gt;
  &lt;/iommu&gt;
8213 8214
&lt;/devices&gt;
...
J
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8215 8216 8217 8218 8219 8220 8221 8222
</pre>
    <dl>
      <dt><code>model</code></dt>
      <dd>
        <p>
          Currently only the <code>intel</code> model is supported.
        </p>
      </dd>
8223 8224 8225 8226 8227 8228 8229 8230 8231 8232 8233 8234 8235 8236 8237 8238 8239 8240
      <dt><code>driver</code></dt>
      <dd>
        <p>
          The <code>driver</code> subelement can be used to configure
          additional options:
        </p>
        <dl>
          <dt><code>intremap</code></dt>
          <dd>
            <p>
              The <code>intremap</code> attribute with possible values
              <code>on</code> and <code>off</code> can be used to
              turn on interrupt remapping, a part of the VT-d functionality.
              Currently this requires split I/O APIC
              (<code>&lt;ioapic driver='qemu'/&gt;</code>).
              <span class="since">Since 3.4.0</span> (QEMU/KVM only)
            </p>
          </dd>
8241 8242 8243 8244 8245 8246 8247 8248 8249
          <dt><code>caching_mode</code></dt>
          <dd>
            <p>
              The <code>caching_mode</code> attribute with possible values
              <code>on</code> and <code>off</code> can be used to
              turn on the VT-d caching mode (useful for assigned devices).
              <span class="since">Since 3.4.0</span> (QEMU/KVM only)
            </p>
          </dd>
8250 8251 8252 8253 8254 8255 8256 8257 8258 8259 8260 8261 8262
          <dt><code>eim</code></dt>
          <dd>
            <p>
              The <code>eim</code> attribute (with possible values
              <code>on</code> and <code>off</code>) can be used to
              configure Extended Interrupt Mode. A q35 domain with
              split I/O APIC (as described in
              <a href="#elementsFeatures">hypervisor features</a>),
              and both interrupt remapping and EIM turned on for
              the IOMMU, will be able to use more than 255 vCPUs.
              <span class="since">Since 3.4.0</span> (QEMU/KVM only)
            </p>
          </dd>
J
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8263 8264 8265 8266 8267 8268 8269 8270 8271 8272
          <dt><code>iotlb</code></dt>
          <dd>
            <p>
              The <code>iotlb</code> attribute with possible values
              <code>on</code> and <code>off</code> can be used to
              turn on the IOTLB used to cache address translation
              requests from devices.
              <span class="since">Since 3.5.0</span> (QEMU/KVM only)
            </p>
          </dd>
8273 8274
        </dl>
      </dd>
J
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8275 8276
    </dl>

J
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8277 8278 8279 8280
    <h3><a id="vsock">Vsock</a></h3>

    <p>A vsock host/guest interface. The <code>model</code> attribute
    defaults to <code>virtio</code>.
8281 8282
    The optional attribute <code>address</code> of the <code>cid</code>
    element specifies the CID assigned to the guest. If the attribute
J
Ján Tomko 已提交
8283 8284 8285 8286 8287 8288 8289 8290
    <code>auto</code> is set to <code>yes</code>, libvirt
    will assign a free CID automatically on domain startup.
    <span class="since">Since 4.4.0</span></p>

<pre>
...
&lt;devices&gt;
  &lt;vsock model='virtio'&gt;
8291
    &lt;cid auto='no' address='3'/&gt;
J
Ján Tomko 已提交
8292 8293 8294 8295 8296
  &lt;/vsock&gt;
&lt;/devices&gt;
...</pre>


8297
    <h3><a id="seclabel">Security label</a></h3>
8298 8299 8300

    <p>
      The <code>seclabel</code> element allows control over the
8301 8302 8303 8304 8305
      operation of the security drivers. There are three basic
      modes of operation, 'dynamic' where libvirt automatically
      generates a unique security label, 'static' where the
      application/administrator chooses the labels, or 'none'
      where confinement is disabled. With dynamic
8306 8307 8308 8309 8310
      label generation, libvirt will always automatically
      relabel any resources associated with the virtual machine.
      With static label assignment, by default, the administrator
      or application must ensure labels are set correctly on any
      resources, however, automatic relabeling can be enabled
8311 8312
      if desired.  <span class="since">'dynamic' since 0.6.1, 'static'
      since 0.6.2, and 'none' since 0.9.10.</span>
8313 8314
    </p>

8315 8316 8317 8318 8319 8320 8321
    <p>
      If more than one security driver is used by libvirt, multiple
      <code>seclabel</code> tags can be used, one for each driver and
      the security driver referenced by each tag can be defined using
      the attribute <code>model</code>
    </p>

8322
    <p>
8323
      Valid input XML configurations for the top-level security label
8324 8325 8326 8327
      are:
    </p>

    <pre>
8328
&lt;seclabel type='dynamic' model='selinux'/&gt;
8329

8330 8331 8332
&lt;seclabel type='dynamic' model='selinux'&gt;
  &lt;baselabel&gt;system_u:system_r:my_svirt_t:s0&lt;/baselabel&gt;
&lt;/seclabel&gt;
8333

8334 8335 8336
&lt;seclabel type='static' model='selinux' relabel='no'&gt;
  &lt;label&gt;system_u:system_r:svirt_t:s0:c392,c662&lt;/label&gt;
&lt;/seclabel&gt;
8337

8338 8339 8340
&lt;seclabel type='static' model='selinux' relabel='yes'&gt;
  &lt;label&gt;system_u:system_r:svirt_t:s0:c392,c662&lt;/label&gt;
&lt;/seclabel&gt;
8341

8342
&lt;seclabel type='none'/&gt;
8343 8344
    </pre>

8345 8346 8347 8348 8349 8350 8351
    <p>
      If no 'type' attribute is provided in the input XML, then
      the security driver default setting will be used, which
      may be either 'none' or 'dynamic'. If a 'baselabel' is set
      but no 'type' is set, then the type is presumed to be 'dynamic'
    </p>

8352 8353 8354 8355 8356 8357 8358 8359 8360
    <p>
      When viewing the XML for a running guest with automatic
      resource relabeling active, an additional XML element,
      <code>imagelabel</code>, will be included. This is an
      output-only element, so will be ignored in user supplied
      XML documents
    </p>
    <dl>
      <dt><code>type</code></dt>
8361 8362 8363
      <dd>Either <code>static</code>, <code>dynamic</code> or <code>none</code>
        to determine whether libvirt automatically generates a unique security
        label or not.
8364 8365 8366 8367 8368 8369 8370 8371 8372 8373 8374 8375 8376
      </dd>
      <dt><code>model</code></dt>
      <dd>A valid security model name, matching the currently
        activated security model
      </dd>
      <dt><code>relabel</code></dt>
      <dd>Either <code>yes</code> or <code>no</code>. This must always
        be <code>yes</code> if dynamic label assignment is used. With
        static label assignment it will default to <code>no</code>.
      </dd>
      <dt><code>label</code></dt>
      <dd>If static labelling is used, this must specify the full
        security label to assign to the virtual domain. The format
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        of the content depends on the security driver in use:
        <ul>
          <li>SELinux: a SELinux context.</li>
          <li>AppArmor: an AppArmor profile.</li>
          <li>
            DAC: owner and group separated by colon. They can be
            defined both as user/group names or uid/gid. The driver will first
            try to parse these values as names, but a leading plus sign can
            used to force the driver to parse them as uid or gid.
          </li>
        </ul>
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      </dd>
      <dt><code>baselabel</code></dt>
      <dd>If dynamic labelling is used, this can optionally be
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        used to specify the base security label that will be used to generate
        the actual label. The format of the content depends on the security
        driver in use.

        The SELinux driver uses only the <code>type</code> field of the
        baselabel in the generated label. Other fields are inherited from
        the parent process when using SELinux baselabels.

        (The example above demonstrates the use of <code>my_svirt_t</code>
        as the value for the <code>type</code> field.)
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      </dd>
      <dt><code>imagelabel</code></dt>
      <dd>This is an output only element, which shows the
        security label used on resources associated with the virtual domain.
        The format of the content depends on the security driver in use
      </dd>
    </dl>

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    <p>When relabeling is in effect, it is also possible to fine-tune
      the labeling done for specific source file names, by either
      disabling the labeling (useful if the file lives on NFS or other
      file system that lacks security labeling) or requesting an
      alternate label (useful when a management application creates a
      special label to allow sharing of some, but not all, resources
      between domains), <span class="since">since 0.9.9</span>.  When
      a <code>seclabel</code> element is attached to a specific path
      rather than the top-level domain assignment, only the
      attribute <code>relabel</code> or the
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      sub-element <code>label</code> are supported.  Additionally,
      <span class="since">since 1.1.2</span>, an output-only
      element <code>labelskip</code> will be present for active
      domains on disks where labeling was skipped due to the image
      being on a file system that lacks security labeling.
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    </p>

8426
    <h3><a id="keywrap">Key Wrap</a></h3>
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       <p>The content of the optional <code>keywrap</code> element specifies
        whether the guest will be allowed to perform the S390 cryptographic key
        management operations. A clear key can be protected by encrypting it
        under a unique wrapping key that is generated for each guest VM running
        on the host. Two variations of wrapping keys are generated: one version
        for encrypting protected keys using the DEA/TDEA algorithm, and another
        version for keys encrypted using the AES algorithm. If a
        <code>keywrap</code> element is not included, the guest will be granted
        access to both AES and DEA/TDEA key wrapping by default.</p>

        <pre>
&lt;domain&gt;
  ...
  &lt;keywrap&gt;
    &lt;cipher name='aes' state='off'/&gt;
  &lt;/keywrap&gt;
  ...
&lt;/domain&gt;
</pre>
    <p>
      At least one <code>cipher</code> element must be nested within the
      <code>keywrap</code> element.
    </p>
    <dl>
      <dt><code>cipher</code></dt>
      <dd>The <code>name</code> attribute identifies the algorithm
        for encrypting a protected key. The values supported for this attribute
        are <code>aes</code> for encryption under the AES wrapping key, or
        <code>dea</code> for encryption under the DEA/TDEA wrapping key. The
        <code>state</code> attribute indicates whether the cryptographic key
        management operations should be turned on for the specified encryption
        algorithm. The value can be set to <code>on</code> or <code>off</code>.
      </dd>
    </dl>

    <p>Note: DEA/TDEA is synonymous with DES/TDES.</p>

8465
    <h3><a id="sev">Launch Security</a></h3>
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    <p>
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       The contents of the <code>&lt;launchSecurity type='sev'&gt;</code> element
8469
       is used to provide the guest owners input used for creating an encrypted
8470
       VM using the AMD SEV feature (Secure Encrypted Virtualization).
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       SEV is an extension to the AMD-V architecture which supports running
       encrypted virtual machine (VMs) under the control of KVM. Encrypted
       VMs have their pages (code and data) secured such that only the guest
       itself has access to the unencrypted version. Each encrypted VM is
       associated with a unique encryption key; if its data is accessed to a
       different entity using a different key the encrypted guests data will
       be incorrectly decrypted, leading to unintelligible data.

       For more information see various input parameters and its format see the SEV API spec
       <a href="https://support.amd.com/TechDocs/55766_SEV-KM%20API_Specification.pdf"> https://support.amd.com/TechDocs/55766_SEV-KM%20API_Specification.pdf </a>
       <span class="since">Since 4.4.0</span>
       </p>
    <pre>
&lt;domain&gt;
  ...
8487
  &lt;launchSecurity type='sev'&gt;
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    &lt;policy&gt;0x0001&lt;/policy&gt;
    &lt;cbitpos&gt;47&lt;/cbitpos&gt;
    &lt;reducedPhysBits&gt;1&lt;/reducedPhysBits&gt;
    &lt;dhCert&gt;RBBBSDDD=FDDCCCDDDG&lt;/dhCert&gt;
    &lt;session&gt;AAACCCDD=FFFCCCDSDS&lt;/session&gt;
8493
  &lt;/launchSecurity&gt;
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  ...
&lt;/domain&gt;
</pre>

    <dl>
      <dt><code>cbitpos</code></dt>
      <dd>The required <code>cbitpos</code> element provides the C-bit (aka encryption bit)
      location in guest page table entry. The value of <code>cbitpos</code> is
      hypervisor dependent and can be obtained through the <code>sev</code> element
      from the domain capabilities.
      </dd>
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      <dt><code>reducedPhysBits</code></dt>
      <dd>The required <code>reducedPhysBits</code> element provides the physical
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      address bit reducation. Similar to <code>cbitpos</code> the value of <code>
      reduced-phys-bit</code> is hypervisor dependent and can be obtained
      through the <code>sev</code> element from the domain capabilities.
      </dd>
      <dt><code>policy</code></dt>
      <dd>The required <code>policy</code> element provides the guest policy
      which must be maintained by the SEV firmware. This policy is enforced by
      the firmware and restricts what configuration and operational commands
      can be performed on this guest by the hypervisor. The guest policy
      provided during guest launch is bound to the guest and cannot be changed
      throughout the lifetime of the guest. The policy is also transmitted
      during snapshot and migration flows and enforced on the destination platform.

      The guest policy is a 4 unsigned byte with the fields shown in Table:

      <table class="top_table">
        <tr>
          <th> Bit(s) </th>
          <th> Description </th>
        </tr>
        <tr>
          <td> 0 </td>
          <td> Debugging of the guest is disallowed when set </td>
        </tr>
        <tr>
          <td> 1 </td>
          <td> Sharing keys with other guests is disallowed when set </td>
        </tr>
        <tr>
          <td> 2 </td>
          <td> SEV-ES is required when set</td>
        </tr>
        <tr>
          <td> 3 </td>
          <td> Sending the guest to another platform is disallowed when set</td>
        </tr>
        <tr>
          <td> 4 </td>
          <td> The guest must not be transmitted to another platform that is
               not in the domain when set. </td>
        </tr>
        <tr>
          <td> 5 </td>
          <td> The guest must not be transmitted to another platform that is
               not SEV capable when set. </td>
        </tr>
        <tr>
          <td> 6:15 </td>
          <td> reserved </td>
        </tr>
        <tr>
          <td> 16:32 </td>
          <td> The guest must not be transmitted to another platform with a
               lower firmware version. </td>
        </tr>
      </table>

      </dd>
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      <dt><code>dhCert</code></dt>
      <dd>The optional <code>dhCert</code> element provides the guest owners
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      base64 encoded Diffie-Hellman (DH) key. The key is used to negotiate a
      master secret key between the SEV firmware and guest owner. This master
      secret key is then used to establish a trusted channel between SEV
      firmware and guest owner.
      </dd>
      <dt><code>session</code></dt>
      <dd>The optional <code>session</code> element provides the guest owners
      base64 encoded session blob defined in the SEV API spec.

      See SEV spec LAUNCH_START section for the session blob format.
      </dd>
    </dl>

8580
    <h2><a id="examples">Example configs</a></h2>
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    <p>
      Example configurations for each driver are provide on the
      driver specific pages listed below
    </p>

    <ul>
      <li><a href="drvxen.html#xmlconfig">Xen examples</a></li>
      <li><a href="drvqemu.html#xmlconfig">QEMU/KVM examples</a></li>
    </ul>
  </body>
</html>