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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<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>


    <h2><a name="elements">Element and attribute overview</a></h2>

    <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>


    <h3><a name="elementsMetadata">General metadata</a></h3>

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<pre>
&lt;domain type='xen' id='3'&gt;
  &lt;name&gt;fv0&lt;/name&gt;
  &lt;uuid&gt;4dea22b31d52d8f32516782e98ab3fa0&lt;/uuid&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>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 name="elementsOS">Operating system booting</a></h3>

    <p>
      There are a number of different ways to boot virtual machines
      each with their own pros and cons.
    </p>

    <h4><a name="elementsOSBIOS">BIOS bootloader</a></h4>

    <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>
  ...
  &lt;os&gt;
    &lt;type&gt;hvm&lt;/type&gt;
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    &lt;loader readonly='yes' type='rom'&gt;/usr/lib/xen/boot/hvmloader&lt;/loader&gt;
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    &lt;nvram template='/usr/share/OVMF/OVMF_VARS.fd'&gt;/var/lib/libvirt/nvram/guest_VARS.fd&lt;/nvram&gt;
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    &lt;boot dev='hd'/&gt;
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    &lt;boot dev='cdrom'/&gt;
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    &lt;bootmenu enable='yes' timeout='3000'/&gt;
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    &lt;smbios mode='sysinfo'/&gt;
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    &lt;bios useserial='yes' rebootTimeout='0'/&gt;
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  &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
        <code>pflash</code>.</dd>
      <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>

    <h4><a name="elementsOSBootloader">Host bootloader</a></h4>

    <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>
  ...
  &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>

    <h4><a name="elementsOSKernel">Direct kernel boot</a></h4>

    <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>
  ...
  &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;
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    &lt;dtb&gt;/root/ppc.dtb&lt;/dtb&gt;
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  &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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    </dl>

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    <h4><a name="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>

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


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    <h3><a name="elementsSysinfo">SMBIOS System Information</a></h3>

    <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>
  ...
  &lt;os&gt;
    &lt;smbios mode='sysinfo'/&gt;
    ...
  &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;
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      &lt;entry name='product'&gt;Virt-Manager&lt;/entry&gt;
      &lt;entry name='version'&gt;0.9.4&lt;/entry&gt;
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    &lt;/system&gt;
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    &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;/sysinfo&gt;
  ...</pre>

    <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>
        </dl>
      </dd>
    </dl>

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    <h3><a name="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;/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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    </dl>

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    <h3><a name="elementsIOThreadsAllocation">IOThreads Allocation</a></h3>
      <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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        virtio-blk-pci and virtio-blk-ccw target storage devices. There
        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>
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    <h3><a name="elementsCPUTuning">CPU Tuning</a></h3>

<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;vcpusched vcpus='0-4,^3' scheduler='fifo' priority='1'/&gt;
    &lt;iothreadsched iothreads='2' scheduler='batch'/&gt;
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  &lt;/cputune&gt;
  ...
&lt;/domain&gt;
</pre>

    <dl>
619
      <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>
626
      <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>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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    </dl>


    <h3><a name="elementsMemoryAllocation">Memory Allocation</a></h3>

<pre>
&lt;domain&gt;
  ...
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  &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;
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  ...
&lt;/domain&gt;
</pre>

    <dl>
      <dt><code>memory</code></dt>
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      <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
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        minimum, such as 4000KiB.

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

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        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>
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      </dd>

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      <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>


    <h3><a name="elementsMemoryBacking">Memory Backing</a></h3>

<pre>
&lt;domain&gt;
  ...
  &lt;memoryBacking&gt;
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    &lt;hugepages&gt;
      &lt;page size="1" unit="G" nodeset="0-3,5"/&gt;
      &lt;page size="2" unit="M" nodeset="4"/&gt;
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    &lt;/hugepages&gt;
821
    &lt;nosharepages/&gt;
822
    &lt;locked/&gt;
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  &lt;/memoryBacking&gt;
  ...
&lt;/domain&gt;
</pre>

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

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    <dl>
833 834
      <dt><code>hugepages</code></dt>
      <dd>This tells the hypervisor that the guest should have its memory
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      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
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        be allowed to swap them out. For QEMU/KVM this requires
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        <code>hard_limit</code> <a href="#elementsMemoryTuning">memory tuning</a>
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        element to be used and set to the maximum memory configured for the
        domain plus any memory consumed by the QEMU process itself.
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        <span class="since">Since 1.0.6</span></dd>
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    </dl>


    <h3><a name="elementsMemoryTuning">Memory Tuning</a></h3>

<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;
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  &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>
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        since 0.9.11</span>
        Possible values for all *_limit parameters are in range from 0 to
        VIR_DOMAIN_MEMORY_PARAM_UNLIMITED.</dd>
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      <dt><code>hard_limit</code></dt>
      <dd> The optional <code>hard_limit</code> element is the maximum memory
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        the guest can use. The units for this value are kibibytes (i.e. blocks
897
        of 1024 bytes). <strong>However, users of QEMU and KVM are strongly
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        advised not to set this limit as domain may get killed by the kernel
        if the guess is too low. To determine the memory needed for a process
        to run is an
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        <a href="http://en.wikipedia.org/wiki/Undecidable_problem">
        undecidable problem</a>.</strong></dd>
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      <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
906
        kibibytes (i.e. blocks of 1024 bytes)</dd>
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      <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
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        kibibytes (i.e. blocks of 1024 bytes). This has to be more than
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        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
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        kibibytes (i.e. blocks of 1024 bytes). This element is only supported
        by VMware ESX and OpenVZ drivers.</dd>
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    </dl>


    <h3><a name="elementsNUMATuning">NUMA Node Tuning</a></h3>

<pre>
&lt;domain&gt;
  ...
  &lt;numatune&gt;
    &lt;memory mode="strict" nodeset="1-4,^3"/&gt;
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    &lt;memnode cellid="0" mode="strict" nodeset="1"/&gt;
    &lt;memnode cellid="2" mode="preferred" nodeset="2"/&gt;
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  &lt;/numatune&gt;
  ...
&lt;/domain&gt;
</pre>

    <dl>
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      <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>
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      </dd>
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      <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.

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        <span class='since'>Since 0.9.3</span>
      </dd>
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      <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>

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    <h3><a name="elementsBlockTuning">Block I/O Tuning</a></h3>
<pre>
&lt;domain&gt;
  ...
  &lt;blkiotune&gt;
    &lt;weight&gt;800&lt;/weight&gt;
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    &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;
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      &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;
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    &lt;/device&gt;
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  &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
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        omitted, it defaults to the OS provided
        defaults. <span class="since">Since 0.8.8</span></dd>
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      <dt><code>weight</code></dt>
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      <dd> The optional <code>weight</code> element is the overall I/O
        weight of the guest. The value should be in the range [100,
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        1000]. After kernel 2.6.39, the value could be in the
        range [10, 1000].</dd>
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      <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
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        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,
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        1000]. After kernel 2.6.39, the value could be in the
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        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>
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    <h3><a name="resPartition">Resource partitioning</a></h3>

    <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
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      element <code>partition</code> whose content defines the absolute path
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      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>
  ...
  &lt;resource&gt;
    &lt;partition&gt;/virtualmachines/production&lt;/partition&gt;
  &lt;/resource&gt;
  ...
</pre>

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

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    <h3><a name="elementsCPU">CPU model and topology</a></h3>

    <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>

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<pre>
  ...
  &lt;cpu match='exact'&gt;
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    &lt;model fallback='allow'&gt;core2duo&lt;/model&gt;
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    &lt;vendor&gt;Intel&lt;/vendor&gt;
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    &lt;topology sockets='1' cores='2' threads='1'/&gt;
    &lt;feature policy='disable' name='lahf_lm'/&gt;
  &lt;/cpu&gt;
  ...</pre>
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<pre>
  &lt;cpu mode='host-model'&gt;
    &lt;model fallback='forbid'/&gt;
    &lt;topology sockets='1' cores='2' threads='1'/&gt;
  &lt;/cpu&gt;
  ...</pre>

<pre>
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  &lt;cpu mode='host-passthrough'&gt;
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    &lt;feature policy='disable' name='lahf_lm'/&gt;
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  ...</pre>

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    <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>

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<pre>
  ...
  &lt;cpu&gt;
    &lt;topology sockets='1' cores='2' threads='1'/&gt;
  &lt;/cpu&gt;
  ...</pre>
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    <dl>
      <dt><code>cpu</code></dt>
      <dd>The <code>cpu</code> element is the main container for describing
        guest CPU requirements. Its <code>match</code> attribute specified how
        strictly has the virtual CPU provided to the guest match these
        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
            requested CPU.</dd>
          <dt><code>exact</code></dt>
          <dd>The virtual CPU provided to the guest will exactly match the
            specification</dd>
          <dt><code>strict</code></dt>
          <dd>The guest will not be created unless the host CPU does exactly
            match the specification.</dd>
        </dl>
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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>.
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        <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
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          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. <strong>Beware</strong>, due to the
          way libvirt detects host CPU and due to the fact libvirt does not
          talk to QEMU/KVM when creating the CPU model, CPU configuration
          created using <code>host-model</code> may not work as expected. The
          guest CPU may differ from the configuration and it may also confuse
          guest OS by using a combination of CPU features and other parameters
          (such as CPUID level) that don't work. Until these issues are fixed,
          it's a good idea to avoid using <code>host-model</code> and use
          <code>custom</code> mode with just the CPU model from host
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          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
          <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>
  &lt;cpu mode='host-model'&gt;
    &lt;model&gt;power7&lt;/model&gt;
  &lt;/cpu&gt;
  ...</pre>
          </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
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          hit any bugs, you are on your own. Further details of that CPU can
          be changed using <code>feature</code> elements.</dd>
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        </dl>

        In both <code>host-model</code> and <code>host-passthrough</code>
        mode, the real (approximate in <code>host-passthrough</code> mode) CPU
        definition which would be used on current host can be determined by
        specifying <code>VIR_DOMAIN_XML_UPDATE_CPU</code> flag when calling
        <code>virDomainGetXMLDesc</code> API. When running a guest that might
        be prone to operating system reactivation when presented with
        different hardware, and which will be migrated between hosts with
        different capabilities, you can use this output to rewrite XML to the
        <code>custom</code> mode for more robust migration.
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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
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        <code>forbid</code>. The optional <code>vendor_id</code> attribute
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        (<span class="since">Since 0.10.0</span>)  can be used to set the
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        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>

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      <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
        socket, and number of threads per core, respectively.</dd>

      <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>
          <dd>Guest creation will fail unless the feature is supported by host
            CPU.</dd>
          <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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      </dd>
    </dl>

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    <p>
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      Guest NUMA topology can be specified using the <code>numa</code> element.
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      <span class="since">Since 0.9.8</span>
    </p>

<pre>
  ...
  &lt;cpu&gt;
    ...
    &lt;numa&gt;
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      &lt;cell id='0' cpus='0-3' memory='512000' unit='KiB'/&gt;
      &lt;cell id='1' cpus='4-7' memory='512000' unit='KiB' memAccess='shared'/&gt;
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    &lt;/numa&gt;
    ...
  &lt;/cpu&gt;
  ...</pre>

    <p>
      Each <code>cell</code> element specifies a NUMA cell or a NUMA node.
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      <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
      hugepages-backed memory.
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    </p>

    <p>
      This guest NUMA specification is currently available only for QEMU/KVM.
    </p>

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    <h3><a name="elementsEvents">Events configuration</a></h3>
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    <p>
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      It is sometimes necessary to override the default actions taken
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      on various events. Not all hypervisors support all events and actions.
      The actions may be taken as a result of calls to libvirt APIs
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      <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>.
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      Using <code>virsh reboot</code> or <code>virsh shutdown</code> would
      also trigger the event.
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    </p>

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<pre>
  ...
  &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;
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  &lt;on_lockfailure&gt;poweroff&lt;/on_lockfailure&gt;
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  ...</pre>
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    <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
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        the guest requests a poweroff.</dd>
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      <dt><code>on_reboot</code></dt>
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      <dd>The content of this element specifies the action to take when
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        the guest requests a reboot.</dd>
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      <dt><code>on_crash</code></dt>
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      <dd>The content of this element specifies the action to take when
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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
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        released.</dd>
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      <dt><code>restart</code></dt>
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      <dd>The domain will be terminated and then restarted with
        the same configuration.</dd>
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      <dt><code>preserve</code></dt>
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      <dd>The domain will be terminated and its resource preserved
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        to allow analysis.</dd>
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      <dt><code>rename-restart</code></dt>
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      <dd>The domain will be terminated and then restarted with
        a new name.</dd>
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    </dl>

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    <p>
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    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
1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416
      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>

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    <p>
      The <code>on_lockfailure</code> element (<span class="since">since
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      1.0.0</span>) may be used to configure what action should be
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      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>

1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449
    <h3><a name="elementsPowerManagement">Power Management</a></h3>

    <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>
  ...
  &lt;pm&gt;
    &lt;suspend-to-disk enabled='no'/&gt;
1450
    &lt;suspend-to-mem enabled='yes'/&gt;
1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461
  &lt;/pm&gt;
  ...</pre>

    <dl>
      <dt><code>pm</code></dt>
      <dd>These elements enable ('yes') or disable ('no') BIOS support
        for S3 (suspend-to-disk) and S4 (suspend-to-mem) ACPI sleep
        states. If nothing is specified, then the hypervisor will be
        left with its default value.</dd>
    </dl>

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    <h3><a name="elementsFeatures">Hypervisor features</a></h3>

    <p>
      Hypervisors may allow certain CPU / machine features to be
      toggled on/off.
    </p>

1469 1470 1471 1472 1473 1474
<pre>
  ...
  &lt;features&gt;
    &lt;pae/&gt;
    &lt;acpi/&gt;
    &lt;apic/&gt;
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    &lt;hap/&gt;
1476
    &lt;privnet/&gt;
1477
    &lt;hyperv&gt;
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      &lt;relaxed state='on'/&gt;
1479
      &lt;vapic state='on'/&gt;
1480
      &lt;spinlocks state='on' retries='4096'/&gt;
1481 1482 1483 1484 1485
      &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;
1486
    &lt;/hyperv&gt;
1487 1488 1489
    &lt;kvm&gt;
      &lt;hidden state='on'/&gt;
    &lt;/kvm&gt;
1490
    &lt;pvspinlock state='on'/&gt;
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    &lt;gic version='2'/&gt;
1492

1493 1494
  &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
1500 1501
      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>
1513 1514
      <dt><code>apic</code></dt>
      <dd>APIC allows the use of programmable IRQ
1515 1516 1517
      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
1518 1519
      Interrupt) for the guest.
      </dd>
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      <dt><code>hap</code></dt>
1521 1522 1523 1524
      <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>
1526 1527 1528 1529
      <dt><code>viridian</code></dt>
      <dd>Enable Viridian hypervisor extensions for paravirtualizing
        guest operating systems
      </dd>
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      <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>
1536 1537 1538 1539 1540 1541 1542 1543
      <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>
1544
          <th>Since</th>
1545 1546 1547
        </tr>
        <tr>
          <td>relaxed</td>
1548
          <td>Relax constraints on timers</td>
1549
          <td> on, off</td>
1550
          <td><span class="since">1.0.0 (QEMU 2.0)</span></td>
1551 1552 1553 1554 1555
        </tr>
        <tr>
          <td>vapic</td>
          <td>Enable virtual APIC</td>
          <td>on, off</td>
1556
          <td><span class="since">1.1.0 (QEMU 2.0)</span></td>
1557 1558 1559 1560 1561
        </tr>
        <tr>
          <td>spinlocks</td>
          <td>Enable spinlock support</td>
          <td>on, off; retries - at least 4095</td>
1562
          <td><span class="since">1.1.0 (QEMU 2.0)</span></td>
1563
        </tr>
1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579
        <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>
1580
          <td><span class="since">1.3.3 (QEMU 2.6)</span></td>
1581 1582 1583 1584 1585
        </tr>
        <tr>
          <td>stimer</td>
          <td>Enable SyNIC timers</td>
          <td> on, off</td>
1586
          <td><span class="since">1.3.3 (QEMU 2.6)</span></td>
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        </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>
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      </table>
      </dd>
1602 1603 1604 1605 1606 1607
      <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>
1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624
      <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>
          <td><span class="since">2.1.0 (QEMU only)</span></td>
        </tr>
      </table>
      </dd>
1625 1626 1627 1628 1629 1630
      <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>
1631 1632 1633
      <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.
1635 1636
        <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;
1643 1644 1645
          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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    </dl>

    <h3><a name="elementsTime">Time keeping</a></h3>

    <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>

1658 1659
<pre>
  ...
1660 1661 1662
  &lt;clock offset='localtime'&gt;
    &lt;timer name='rtc' tickpolicy='catchup' track='guest'&gt;
      &lt;catchup threshold='123' slew='120' limit='10000'/&gt;
1663
    &lt;/timer&gt;
1664
    &lt;timer name='pit' tickpolicy='delay'/&gt;
1665
  &lt;/clock&gt;
1666
  ...</pre>
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    <dl>
      <dt><code>clock</code></dt>
1670
      <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
1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689
            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.
1694 1695
            <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
1706 1707
            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
1710 1711 1712
            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
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            lost at each reboot. <span class="since">Since 0.7.7</span>
1714 1715
            <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
1720
          <code>timer</code> sub-elements. <span class="since">Since
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          0.8.0</span>
        </p>
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      </dd>
1724 1725
      <dt><code>timer</code></dt>
      <dd>
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        <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
1736 1737 1738
            being modified, and can be one of
            "platform" (currently unsupported),
            "hpet" (libxl, xen, qemu), "kvmclock" (qemu),
1739 1740 1741 1742 1743 1744 1745
            "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>
1756 1757
            <p>
            The <code>tickpolicy</code> attribute determines what
1758
            happens when QEMU misses a deadline for injecting a
1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781
            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>
1791 1792 1793
            <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>
1814
      </dd>
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    </dl>

    <h3><a name="elementsDevices">Devices</a></h3>

    <p>
A
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      The final set of XML elements are all used to describe devices
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      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>

1826 1827 1828 1829 1830 1831
<pre>
  ...
  &lt;devices&gt;
    &lt;emulator&gt;/usr/lib/xen/bin/qemu-dm&lt;/emulator&gt;
  &lt;/devices&gt;
  ...</pre>
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    <dl>
      <dt><code>emulator</code></dt>
      <dd>
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        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.
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      </dd>
    </dl>

    <h4><a name="elementsDisks">Hard drives, floppy disks, CDROMs</a></h4>

    <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>

1852 1853 1854
<pre>
  ...
  &lt;devices&gt;
1855
    &lt;disk type='file' snapshot='external'&gt;
1856
      &lt;driver name="tap" type="aio" cache="default"/&gt;
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      &lt;source file='/var/lib/xen/images/fv0' startupPolicy='optional'&gt;
1858 1859
        &lt;seclabel relabel='no'/&gt;
      &lt;/source&gt;
1860
      &lt;target dev='hda' bus='ide'/&gt;
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      &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;
1866
      &lt;boot order='2'/&gt;
1867 1868 1869 1870
      &lt;encryption type='...'&gt;
        ...
      &lt;/encryption&gt;
      &lt;shareable/&gt;
1871 1872 1873
      &lt;serial&gt;
        ...
      &lt;/serial&gt;
1874
    &lt;/disk&gt;
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      ...
    &lt;disk type='network'&gt;
1877
      &lt;driver name="qemu" type="raw" io="threads" ioeventfd="on" event_idx="off"/&gt;
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      &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;
1882
      &lt;boot order='1'/&gt;
1883
      &lt;transient/&gt;
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      &lt;address type='drive' controller='0' bus='1' unit='0'/&gt;
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    &lt;/disk&gt;
1886 1887 1888 1889
    &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;
1890
        &lt;snapshot name="snapname"/&gt;
1891
        &lt;config file="/path/to/file"/&gt;
1892
      &lt;/source&gt;
1893
      &lt;target dev="hdc" bus="ide"/&gt;
1894 1895 1896 1897
      &lt;auth username='myuser'&gt;
        &lt;secret type='ceph' usage='mypassid'/&gt;
      &lt;/auth&gt;
    &lt;/disk&gt;
1898 1899
    &lt;disk type='block' device='cdrom'&gt;
      &lt;driver name='qemu' type='raw'/&gt;
1900
      &lt;target dev='hdd' bus='ide' tray='open'/&gt;
1901 1902
      &lt;readonly/&gt;
    &lt;/disk&gt;
1903 1904 1905 1906 1907
    &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;
1908
      &lt;target dev='hde' bus='ide' tray='open'/&gt;
1909 1910
      &lt;readonly/&gt;
    &lt;/disk&gt;
1911 1912 1913 1914 1915
    &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;
1916
      &lt;target dev='hdf' bus='ide' tray='open'/&gt;
1917 1918
      &lt;readonly/&gt;
    &lt;/disk&gt;
1919 1920 1921 1922 1923
    &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;
1924
      &lt;target dev='hdg' bus='ide' tray='open'/&gt;
1925 1926
      &lt;readonly/&gt;
    &lt;/disk&gt;
1927 1928 1929 1930 1931
    &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;
1932
      &lt;target dev='hdh' bus='ide' tray='open'/&gt;
1933 1934
      &lt;readonly/&gt;
    &lt;/disk&gt;
1935 1936 1937 1938 1939
    &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;
1940
      &lt;target dev='hdi' bus='ide' tray='open'/&gt;
1941 1942
      &lt;readonly/&gt;
    &lt;/disk&gt;
1943 1944
    &lt;disk type='block' device='lun'&gt;
      &lt;driver name='qemu' type='raw'/&gt;
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      &lt;source dev='/dev/sda'/&gt;
      &lt;target dev='sda' bus='scsi'/&gt;
      &lt;address type='drive' controller='0' bus='0' target='3' unit='0'/&gt;
1948
    &lt;/disk&gt;
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    &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;
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      &lt;blockio logical_block_size='512' physical_block_size='4096'/&gt;
1954
      &lt;target dev='hdj' bus='ide'/&gt;
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    &lt;/disk&gt;
1956 1957 1958
    &lt;disk type='volume' device='disk'&gt;
      &lt;driver name='qemu' type='raw'/&gt;
      &lt;source pool='blk-pool0' volume='blk-pool0-vol0'/&gt;
1959
      &lt;target dev='hdk' bus='ide'/&gt;
1960
    &lt;/disk&gt;
1961 1962 1963 1964 1965 1966
    &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;
      &lt;/source&gt;
      &lt;auth username='myuser'&gt;
1967
        &lt;secret type='iscsi' usage='libvirtiscsi'/&gt;
1968 1969 1970 1971 1972 1973 1974 1975 1976
      &lt;/auth&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;
      &lt;/source&gt;
      &lt;auth username='myuser'&gt;
1977
        &lt;secret type='iscsi' usage='libvirtiscsi'/&gt;
1978
      &lt;/auth&gt;
1979
      &lt;target dev='sdb' bus='scsi'/&gt;
1980 1981 1982 1983 1984
    &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;auth username='myuser'&gt;
1985
        &lt;secret type='iscsi' usage='libvirtiscsi'/&gt;
1986
      &lt;/auth&gt;
1987
      &lt;target dev='vdb' bus='virtio'/&gt;
1988 1989 1990 1991 1992
    &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;auth username='myuser'&gt;
1993
        &lt;secret type='iscsi' usage='libvirtiscsi'/&gt;
1994
      &lt;/auth&gt;
1995
      &lt;target dev='vdc' bus='virtio'/&gt;
1996
    &lt;/disk&gt;
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
    &lt;disk type='file' device='disk'&gt;
      &lt;driver name='qemu' type='qcow2'/&gt;
      &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;
        &lt;/backingStore&gt;
      &lt;/backingStore&gt;
2009
      &lt;target dev='vdd' bus='virtio'/&gt;
2010
    &lt;/disk&gt;
2011 2012
  &lt;/devices&gt;
  ...</pre>
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    <dl>
      <dt><code>disk</code></dt>
      <dd>The <code>disk</code> element is the main container for describing
2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035
      disks (<span class="since">since 0.0.3</span>).
        <dl>
          <dt><code>type</code> attribute
          <span class="since">since 0.0.3</span></dt>
            <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.
            </dd>
          <dt><code>device</code> attribute
          <span class="since">since 0.1.4</span></dt>
            <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
2036 2037
            valid when the <code>type</code> is "block" or "network" for
            <code>protocol='iscsi'</code> or when the <code>type</code>
2038
            is "volume" when using an iSCSI source <code>pool</code>
2039 2040 2041
            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.
2042
            Configured in this manner, the LUN behaves identically to "disk",
2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053
            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').
            </p>
            </dd>
          <dt><code>rawio</code> attribute
          <span class="since">since 0.9.10</span></dt>
            <dd>
2054
            Indicates whether the disk needs rawio capability. Valid
2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069
            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>.
            </dd>
          <dt><code>sgio</code> attribute
          <span class="since">since 1.0.2</span></dt>
            <dd>
2070 2071 2072 2073
            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'.
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            </dd>
          <dt><code>snapshot</code> attribute
          <span class="since">since 0.9.5</span></dt>
            <dd>
            Indicates the default behavior of the disk during disk snapshots:
            "internal" requires a file format such as qcow2 that can store
            both the snapshot and the data changes since the snapshot;
            "external" will separate the snapshot from the live data; and
            "no" means the disk will not participate in snapshots. Read-only
            disks default to "no", while the default for other disks depends
            on the hypervisor's capabilities.  Some hypervisors allow a
            per-snapshot choice as well, during
            <a href="formatsnapshot.html">domain snapshot creation</a>.
            Not all snapshot modes are supported; for example,
            <code>snapshot='yes'</code> with a transient disk generally
            does not make sense.
            </dd>
        </dl>
      </dd>
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      <dt><code>source</code></dt>
2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105
      <dd>Representation of the disk <code>source</code> depends on the
      disk <code>type</code> attribute value as follows:
          <dl>
            <dt><code>type='file'</code>
            <span class="since">since 0.0.3</span></dt>
              <dd>
              The <code>file</code> attribute specifies the fully-qualified
              path to the file holding the disk.
              </dd>
            <dt><code>type='block'</code>
            <span class="since">since 0.0.3</span></dt>
              <dd>
2106 2107
              The <code>dev</code> attribute specifies the fully-qualified path
              to the host device to serve as the disk.
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              </dd>
            <dt><code>type='dir'</code>
            <span class="since">since 0.7.5</span></dt>
              <dd>
              The <code>dir</code> attribute specifies the fully-qualified path
              to the directory to use as the disk.
              </dd>
            <dt><code>type='network'</code>
            <span class="since">since 0.8.7</span></dt>
              <dd>
              The <code>protocol</code> attribute specifies the protocol to
              access to the requested image. Possible values are "nbd",
              "iscsi", "rbd", "sheepdog" or "gluster".  If the
              <code>protocol</code> attribute is "rbd", "sheepdog" or
              "gluster", an additional attribute <code>name</code> is
              mandatory to specify which volume/image will be used. For "nbd",
              the <code>name</code> attribute is optional. 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.,
              <code>iqn.2013-07.com.example:iscsi-pool/1</code>). If not
              specified, the default LUN is zero.
              </dd>
            <dt><code>type='volume'</code>
            <span class="since">since 1.0.5</span></dt>
              <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').
2159 2160 2161 2162 2163 2164 2165

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

2166 2167 2168 2169
              </p>
              </dd>
          </dl>
        With "file", "block", and "volume", one or more optional
2170
        sub-elements <code>seclabel</code>, <a href="#seclabel">described
2171 2172
        below</a> (and <span class="since">since 0.9.9</span>), can be
        used to override the domain security labeling policy for just
2173 2174
        that source file. (NB, for "volume" type disk, <code>seclabel</code>
        is only valid when the specified storage volume is of 'file' or
2175 2176
        'block' type).
        <p>
2177
        The <code>source</code> element may contain the following sub elements:
2178
        </p>
2179 2180 2181 2182 2183

        <dl>
          <dt><code>host</code></dt>
          <dd>
            <p>
2184 2185 2186 2187
            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.

2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216
            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>
2217
                <td> librados default </td>
2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239
              </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>
                <td> only one </td>
                <td> 24007 </td>
              </tr>
            </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>
2240 2241 2242 2243 2244 2245 2246
          <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>
2247 2248 2249 2250 2251 2252 2253 2254
          <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>
2255 2256
        </dl>

2257
        <p>
2258
        For a "file" or "volume" disk type which represents a cdrom or floppy
2259 2260
        (the <code>device</code> attribute), it is possible to define
        policy what to do with the disk if the source file is not accessible.
2261 2262
        (NB, <code>startupPolicy</code> is not valid for "volume" disk unless
         the specified storage volume is of "file" type). This is done by the
2263 2264
        <code>startupPolicy</code> attribute
        (<span class="since">since 0.9.7</span>),
2265
        accepting these values:
2266
        </p>
2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281
        <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>
2282 2283 2284 2285 2286 2287 2288
        <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>
2289
        </dd>
2290 2291
      <dt><code>backingStore</code></dt>
      <dd>
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        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
        file correctly). The following attributes and sub-elements are
        supported in <code>backingStore</code>:
2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344
        <dl>
          <dt><code>type</code> attribute</dt>
          <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>
          <dt><code>index</code> attribute</dt>
          <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>
          <dt><code>format</code> sub-element</dt>
          <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>
          <dt><code>source</code> sub-element</dt>
          <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>
          <dt><code>backingStore</code> sub-element</dt>
          <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>
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      <dt><code>mirror</code></dt>
      <dd>
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        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
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        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
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        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
2360 2361 2362 2363 2364 2365
        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
2366
        copying.  For now, this element only valid in output; it is
2367 2368 2369 2370 2371 2372 2373
        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.
2374
      </dd>
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      <dt><code>target</code></dt>
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      <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
2384 2385
        "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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        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
2388 2389 2390 2391
        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.
2392 2393 2394 2395
        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;
2396
        <code>tray</code> attribute since 0.9.11; "usb" attribute value since
2397 2398
        after 0.4.4; "sata" attribute value since 0.9.7; "removable" attribute
        value since 1.1.3</span>
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      </dd>
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      <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>
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          <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
            size of I/O operations per second.</dd>
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        </dl>
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      </dd>
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      <dt><code>driver</code></dt>
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      <dd>
        The optional driver element allows specifying further details
        related to the hypervisor driver used to provide the disk.
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        <span class="since">Since 0.1.8</span>
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        <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",
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            "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
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            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
            0.9.7</span> The default setting of error_policy is "report".
            There is also an
            optional <code>rerror_policy</code> that controls behavior
            for read errors only. <span class="since">Since
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            0.9.7</span>. If no rerror_policy is given, error_policy
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            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
            given, the read error policy will be left at its default,
            which is "report".
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          </li>
          <li>
            The optional <code>io</code> attribute controls specific
            policies on I/O; qemu guests support "threads" and
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            "native". <span class="since">Since 0.8.8</span>
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          </li>
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          <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>
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          <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
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            number of interrupts and exits for the guest. The default
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            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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          <li>
            The optional <code>copy_on_read</code> attribute controls
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            whether to copy read backing file into the image file. The
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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
            to discard (also known as "trim" or "unmap") requests are
            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).
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            <span class='since'>Since 1.0.6 (QEMU and KVM only)</span>
          </li>
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          <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>
            value. Multiple devices may be assigned to the same IOThread and
            are numbered from 1 to the domain iothreads value.
            <span class='since'>Since 1.2.8 (QEMU only)</span>
          </li>
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        </ul>
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      </dd>
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      <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>
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      <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
        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>
      </dd>
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      <dt><code>encryption</code></dt>
      <dd>If present, specifies how the volume is encrypted.  See
        the <a href="formatstorageencryption.html">Storage Encryption</a> page
        for more information.
      </dd>
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      <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
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        attribute <code>device='cdrom'</code>.
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      </dd>
2590 2591 2592 2593 2594
      <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>
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      <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>
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      <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>.
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          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'.
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          <span class="since">Since 0.7.1</span>
      </dd>
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      <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
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        of 16 hexadecimal digits and must be unique (at least among
        disks of a single domain)
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        <span class='since'>Since 0.10.1</span>
      </dd>
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      <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>,
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        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
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        <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.
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      </dd>
      <dt><code>auth</code></dt>
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      <dd>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
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        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
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        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>
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        attribute matching the key that was specified in the
        secret object.  <span class="since">libvirt 0.9.7</span>
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      </dd>
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      <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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      <dt><code>blockio</code></dt>
      <dd>If present, the <code>blockio</code> element allows
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        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.
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          </dd>
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          <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.
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          </dd>
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        </dl>
      </dd>
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    </dl>

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    <h4><a name="elementsFilesystems">Filesystems</a></h4>

    <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>
  ...
  &lt;devices&gt;
    &lt;filesystem type='template'&gt;
      &lt;source name='my-vm-template'/&gt;
      &lt;target dir='/'/&gt;
    &lt;/filesystem&gt;
2723
    &lt;filesystem type='mount' accessmode='passthrough'&gt;
2724
      &lt;driver type='path' wrpolicy='immediate'/&gt;
2725 2726 2727 2728
      &lt;source dir='/export/to/guest'/&gt;
      &lt;target dir='/import/from/host'/&gt;
      &lt;readonly/&gt;
    &lt;/filesystem&gt;
2729 2730 2731 2732 2733 2734 2735
    &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;
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    ...
  &lt;/devices&gt;
  ...</pre>

    <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>
        <dt><code>type='mount'</code></dt>
        <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>.
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        This is the default <code>type</code> if one is not specified.
2754 2755 2756 2757
        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
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        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>.
2764 2765 2766 2767 2768 2769 2770
        </dd>
        <dt><code>type='template'</code></dt>
        <dd>
        OpenVZ filesystem template. Only used by OpenVZ driver.
        </dd>
        <dt><code>type='file'</code></dt>
        <dd>
2771 2772 2773
        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.
2774 2775 2776
        </dd>
        <dt><code>type='block'</code></dt>
        <dd>
2777 2778 2779
        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>.
2780
        </dd>
2781 2782 2783 2784
        <dt><code>type='ram'</code></dt>
        <dd>
          An in-memory filesystem, using memory from the host OS.
          The source element has a single attribute <code>usage</code>
2785 2786
          which gives the memory usage limit in KiB, unless units
          are specified by the <code>units</code> attribute. Only used
2787 2788
          by LXC driver.
          <span class="since"> (since 0.9.13)</span></dd>
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        <dt><code>type='bind'</code></dt>
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        <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>
2794 2795
        </dl>

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      The filesystem block has an optional attribute <code>accessmode</code>
2797 2798 2799 2800 2801 2802
      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>
2803
        <dt><code>accessmode='passthrough'</code></dt>
2804 2805
        <dd>
        The <code>source</code> is accessed with the permissions of the
2806
        user inside the guest. This is the default <code>accessmode</code> if
2807 2808 2809
        one is not specified.
        <a href="http://lists.gnu.org/archive/html/qemu-devel/2010-05/msg02673.html">More info</a>
        </dd>
2810
        <dt><code>accessmode='mapped'</code></dt>
2811 2812 2813 2814 2815
        <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>
2816
        <dt><code>accessmode='squash'</code></dt>
2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827
        <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>

2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838
      <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
2839 2840
            supports a type of "loop", with a format of "raw" or
            "nbd" with any format. QEMU supports a type of "path"
2841
            or "handle", but no formats. Virtuozzo driver supports
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            a type of "ploop" with a format of "ploop".
2843 2844 2845 2846
          </li>
        </ul>
      </dd>

2847 2848 2849 2850 2851
      <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
2852
        be used with <code>type='mount'</code>. The <code>usage</code> attribute
2853 2854
        is used with <code>type='ram'</code> to set the memory limit in KiB,
        unless units are specified by the <code>units</code> attribute.
2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866
      </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>
2867
        Enables exporting filesystem as a readonly mount for guest, by
2868 2869
        default read-write access is given (currently only works for
        QEMU/KVM driver).
2870
      </dd>
2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884

      <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>
2885 2886
    </dl>

2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905
    <h4><a name="elementsAddress">Device Addresses</a></h4>

    <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
2906
      uses <code>type='drive'</code>, while
2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933
      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>
      <dt><code>type='pci'</code></dt>
      <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
        have multiple functions used.
      </dd>
      <dt><code>type='drive'</code></dt>
      <dd>Drive addresses have the following additional
        attributes: <code>controller</code> (a 2-digit controller
        number), <code>bus</code> (a 2-digit bus number),
2934
        <code>target</code> (a 2-digit target number),
2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947
        and <code>unit</code> (a 2-digit unit number on the bus).
      </dd>
      <dt><code>type='virtio-serial'</code></dt>
      <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>
      <dt><code>type='ccid'</code></dt>
      <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>
2948
      </dd>
2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963
      <dt><code>type='usb'</code></dt>
      <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>
      <dt><code>type='spapr-vio'</code></dt>
      <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>
2964 2965 2966 2967 2968 2969 2970 2971 2972 2973
      </dd>
      <dt><code>type='ccw'</code></dt>
      <dd>s390 guests with a <code>machine</code> value of
        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
2974 2975
        cssid=0xfe and ssid=0. Virtio-ccw devices must have their cssid
        set to 0xfe.
2976
        <span class="since">Since 1.0.4</span>
2977
      </dd>
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      <dt><code>type='isa'</code></dt>
      <dd>ISA addresses have the following additional
        attributes: <code>iobase</code> and <code>irq</code>.
        <span class="since">Since 1.2.1</span>
      </dd>
2983 2984
    </dl>

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2985 2986 2987
    <h4><a name="elementsControllers">Controllers</a></h4>

    <p>
2988
      Depending on the guest architecture, some device buses can
2989 2990
      appear more than once, with a group of virtual devices tied to a
      virtual controller.  Normally, libvirt can automatically infer such
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2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008
      controllers without requiring explicit XML markup, but sometimes
      it is necessary to provide an explicit controller element.
    </p>

<pre>
  ...
  &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;/devices&gt;
  ...</pre>

    <p>
      Each controller has a mandatory attribute <code>type</code>,
3009
      which must be one of "ide", "fdc", "scsi", "sata", "usb",
J
Ján Tomko 已提交
3010
      "ccid", "virtio-serial" or "pci", and a mandatory
3011 3012 3013 3014 3015
      attribute <code>index</code> which is the decimal integer
      describing in which order the bus controller is encountered (for
      use in <code>controller</code> attributes
      of <code>&lt;address&gt;</code> elements).  The "virtio-serial"
      controller has two additional optional
E
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3016 3017 3018
      attributes <code>ports</code> and <code>vectors</code>, which
      control how many devices can be connected through the
      controller.  A "scsi" controller has an optional
3019
      attribute <code>model</code>, which is one of "auto", "buslogic",
3020
      "ibmvscsi", "lsilogic", "lsisas1068", "lsisas1078", "virtio-scsi" or
3021 3022 3023 3024 3025 3026
      "vmpvscsi".  A "usb" 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", "vt82c686b-uhci",
      "pci-ohci" or "nec-xhci".  Additionally,
      <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
3027 3028 3029
      used.  <span class="since">Since 1.0.5</span>, no default USB controller
      will be built on s390.  The PowerPC64 "spapr-vio" addresses do not have an
      associated controller.
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3030 3031 3032 3033 3034 3035
    </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
3036
      semantics <a href="#elementsAddress">given above</a>.
E
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3037 3038
    </p>

3039 3040
    <p>
      An optional sub-element <code>driver</code> can specify the driver
3041
      specific options:
3042
    </p>
3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065
    <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>
3066 3067 3068 3069 3070 3071 3072 3073
      <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>
3074
    </dl>
3075 3076 3077 3078 3079 3080
    <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.
3081 3082 3083 3084 3085
      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>.
3086 3087 3088 3089 3090 3091 3092 3093 3094 3095
    </p>

<pre>
  ...
  &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;
3096
      &lt;address type='pci' domain='0' bus='0' slot='4' function='0' multifunction='on'/&gt;
3097 3098 3099
    &lt;/controller&gt;
    ...
  &lt;/devices&gt;
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3100 3101 3102 3103
  ...</pre>

    <p>
      PCI controllers have an optional <code>model</code> attribute with
3104
      possible values <code>pci-root</code>, <code>pcie-root</code>,
3105
      <code>pcie-root-port</code>, <code>pci-bridge</code>,
3106
      <code>dmi-to-pci-bridge</code>, <code>pcie-switch-upstream-port</code>,
3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118
      <code>pcie-switch-downstream-port</code>, <code>pci-expander-bus</code>,
      or <code>pcie-expander-bus</code>.  (pci-root and
      pci-bridge <span class="since">since 1.0.5</span>, pcie-root and
      dmi-to-pci-bridge <span class="since">since 1.1.2</span>,
      pcie-root-port, pcie-switch-upstream-port,
      pcie-switch-downstream-port <span class="since">since
      1.2.19</span>, and pci-expander-bus and
      pcie-expander-bus <span class="since">since 1.3.4</span>) The
      root controllers (<code>pci-root</code>
      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
3119 3120 3121 3122 3123
      <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>
3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136
    <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>
3137 3138
    <p>
      PCI controllers also have an optional
3139 3140 3141
      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
3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159
      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
        must be between 0 and 255.
      </dd>
3160 3161
      <dt><code>chassis</code></dt>
      <dd>
3162 3163
        pcie-root-port and pcie-switch-downstream-port controllers can
        also have a <code>chassis</code> attribute in
3164 3165 3166 3167 3168 3169 3170
        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>
3171 3172 3173
        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
3174 3175 3176 3177
        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>
3178 3179
      <dt><code>busNr</code></dt>
      <dd>
3180
        pci-expander-bus and pcie-expander-bus controllers can have an
3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194
        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).
3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211
        <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
          multiple devices into a pcie-expander-bus, you must instead
          connect a pcie-switch-upstream-port to the
          pcie-expander-bus, and multiple pcie-switch-downstream-ports
          to the pcie-switch-downstream-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 numbers above it to accomodate giving out
          one bus number for the upstream-port and one for each
          downstream-port).
        </p>
3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223
      </dd>
      <dt><code>&lt;node&gt;</code></dt>
      <dd>
        pci-expander-bus controllers can have an
        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>
3224
    </dl>
3225
    <p>
L
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3226
      For machine types which provide an implicit PCI bus, the pci-root
J
Ján Tomko 已提交
3227
      controller with index=0 is auto-added and required to use PCI devices.
L
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3228
      pci-root has no address.
3229 3230 3231
      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
3232 3233 3234 3235 3236 3237 3238 3239 3240 3241
      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>
  ...
  &lt;devices&gt;
    &lt;controller type='pci' index='0' model='pci-root'/&gt;
    &lt;controller type='pci' index='1' model='pci-bridge'&gt;
L
Laine Stump 已提交
3242
      &lt;address type='pci' domain='0' bus='0' slot='5' function='0' multifunction='off'/&gt;
J
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3243 3244
    &lt;/controller&gt;
  &lt;/devices&gt;
L
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3245 3246 3247 3248 3249 3250 3251
  ...</pre>

    <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
3252 3253 3254 3255 3256 3257
      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
      hotplugged. In order to make standard PCI slots available on a
      system which has a pcie-root controller, a pci controller
3258
      with <code>model='dmi-to-pci-bridge'</code> is automatically
3259 3260 3261 3262
      added, usually at the defacto standard location of slot=0x1e. A
      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
3263 3264 3265
      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
3266
      controller; all guest PCI devices with addresses that are
3267 3268
      auto-determined by libvirt will be placed on this pci-bridge
      device.  (<span class="since">since 1.1.2</span>).
L
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3269
    </p>
3270 3271
    <p>
      Domains with an implicit pcie-root can also add controllers
3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297
      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>)
3298
    </p>
L
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3299 3300 3301 3302
<pre>
  ...
  &lt;devices&gt;
    &lt;controller type='pci' index='0' model='pcie-root'/&gt;
3303 3304 3305 3306 3307 3308
    &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;
L
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  &lt;/devices&gt;
3310 3311
  ...</pre>

3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332 3333
    <h4><a name="elementsLease">Device leases</a></h4>

    <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>
  ...
  &lt;devices&gt;
    ...
    &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>

    <dl>
3334
      <dt><code>lockspace</code></dt>
3335 3336 3337 3338
      <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>
3339
      <dt><code>key</code></dt>
3340 3341 3342 3343
      <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>
3344
      <dt><code>target</code></dt>
3345 3346 3347 3348 3349 3350
      <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
        require a offset, just pass 0.
      </dd>
    </dl>
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3351

3352 3353
    <h4><a name="elementsHostDev">Host device assignment</a></h4>

3354
    <h5><a name="elementsHostDevSubsys">USB / PCI / SCSI devices</a></h5>
3355 3356

    <p>
H
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3357
      USB, PCI and SCSI devices attached to the host can be passed through
3358
      to the guest using the <code>hostdev</code> element.
H
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3359 3360
      <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>:
3361 3362
    </p>

3363 3364 3365 3366
<pre>
  ...
  &lt;devices&gt;
    &lt;hostdev mode='subsystem' type='usb'&gt;
3367
      &lt;source startupPolicy='optional'&gt;
3368 3369 3370
        &lt;vendor id='0x1234'/&gt;
        &lt;product id='0xbeef'/&gt;
      &lt;/source&gt;
3371
      &lt;boot order='2'/&gt;
3372 3373 3374 3375
    &lt;/hostdev&gt;
  &lt;/devices&gt;
  ...</pre>

3376
    <p>or:</p>
3377 3378 3379 3380

<pre>
  ...
  &lt;devices&gt;
3381
    &lt;hostdev mode='subsystem' type='pci' managed='yes'&gt;
3382
      &lt;source&gt;
3383
        &lt;address domain='0x0000' bus='0x06' slot='0x02' function='0x0'/&gt;
3384
      &lt;/source&gt;
3385
      &lt;boot order='1'/&gt;
3386
      &lt;rom bar='on' file='/etc/fake/boot.bin'/&gt;
3387 3388
    &lt;/hostdev&gt;
  &lt;/devices&gt;
H
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3389 3390 3391 3392 3393 3394 3395
  ...</pre>

    <p>or:</p>

<pre>
  ...
  &lt;devices&gt;
3396
    &lt;hostdev mode='subsystem' type='scsi' sgio='filtered' rawio='yes'&gt;
H
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3397 3398
      &lt;source&gt;
        &lt;adapter name='scsi_host0'/&gt;
3399
        &lt;address bus='0' target='0' unit='0'/&gt;
H
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3400 3401 3402 3403 3404
      &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;
3405
  ...</pre>
3406

J
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3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424

    <p>or:</p>

<pre>
  ...
  &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>

3425 3426 3427
    <dl>
      <dt><code>hostdev</code></dt>
      <dd>The <code>hostdev</code> element is the main container for describing
J
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3428 3429 3430 3431
        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>
3432
          <dt><code>usb</code></dt>
3433 3434 3435
          <dd>USB devices are detached from the host on guest startup
            and reattached after the guest exits or the device is
            hot-unplugged.
J
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3436
          </dd>
3437
          <dt><code>pci</code></dt>
J
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3438 3439 3440
          <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
3441 3442 3443 3444 3445 3446
            <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
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3447
          </dd>
3448
          <dt><code>scsi</code></dt>
J
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3449
          <dd>For SCSI devices, user is responsible to make sure the device
3450 3451 3452 3453 3454 3455
            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>
3456 3457 3458 3459 3460 3461
            (<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
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3462 3463
          </dd>
        </dl>
3464 3465 3466 3467 3468 3469
        <p>
          Note: The <code>managed</code> attribute is only used with PCI devices
          and is ignored by all the other device types, thus setting
          <code>managed</code> explicitly with other than PCI device has the same
          effect as omitting it.
        </p>
O
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3470
      </dd>
3471
      <dt><code>source</code></dt>
J
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3472 3473 3474
      <dd>The source element describes the device as seen from the host using
        the following mechanism to describe:
        <dl>
3475
          <dt><code>usb</code></dt>
J
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3476 3477 3478 3479 3480 3481 3482 3483 3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 3499 3500 3501 3502
          <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>
3503
          <dt><code>pci</code></dt>
J
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3504 3505
          <dd>PCI devices can only be described by their <code>address</code>.
          </dd>
3506
          <dt><code>scsi</code></dt>
J
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3507
          <dd>SCSI devices are described by both the <code>adapter</code>
3508 3509 3510 3511 3512 3513 3514 3515
            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
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3516 3517 3518 3519 3520 3521 3522 3523 3524 3525 3526
            <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>
        </dl>
3527
      </dd>
3528 3529 3530 3531 3532
      <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>
3533 3534 3535 3536 3537 3538
      <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.
3539 3540
      <span class="since">Since 0.8.8</span> for PCI devices,
      <span class="since">Since 1.0.1</span> for USB devices.
3541
      </dd>
3542 3543
      <dt><code>rom</code></dt>
      <dd>The <code>rom</code> element is used to change how a PCI
3544
        device's ROM is presented to the guest. The optional <code>bar</code>
3545 3546 3547 3548 3549 3550 3551
        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
3552
        0.9.7 (QEMU and KVM only)</span>. The optional
3553
        <code>file</code> attribute contains an absolute path to a binary file
3554 3555 3556 3557 3558
        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>.
3559
      </dd>
3560
      <dt><code>address</code></dt>
3561 3562 3563 3564 3565
      <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.
3566
      For PCI devices the element carries 4 attributes allowing to designate
3567
      the device as can be found with the <code>lspci</code> or
3568 3569
      with <code>virsh nodedev-list</code>. For SCSI devices a 'drive'
      address type must be used. <a href="#elementsAddress">See above</a> for
3570 3571 3572 3573 3574 3575 3576 3577
      more details on the address element.</dd>
      <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"
3578
        (the legacy device assignment handled directly by the KVM
3579
        kernel module)<span class="since">Since 1.0.5 (QEMU and KVM
3580 3581 3582 3583 3584 3585 3586 3587
        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").
3588
      </dd>
O
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3589 3590 3591 3592
      <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>
3593 3594 3595 3596 3597
      <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>
3598 3599 3600 3601 3602
        <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>
3603
      </dd>
3604 3605
    </dl>

3606

3607
    <h5><a name="elementsHostDevCaps">Block / character devices</a></h5>
3608 3609 3610 3611

    <p>
      Block / character devices from the host can be passed through
      to the guest using the <code>hostdev</code> element. This is
3612 3613
      only possible with container based virtualization. Devices are specified
      by a fully qualified path.
3614 3615 3616 3617 3618 3619 3620 3621 3622 3623 3624 3625 3626 3627 3628 3629 3630 3631 3632 3633
      <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;
3634 3635 3636
...
    </pre>

O
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3637
    <pre>
3638 3639 3640 3641 3642 3643
...
&lt;hostdev mode='capabilities' type='net'&gt;
  &lt;source&gt;
    &lt;interface&gt;eth0&lt;/interface&gt;
  &lt;/source&gt;
&lt;/hostdev&gt;
3644 3645 3646 3647 3648 3649 3650
...
    </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
3651 3652
        always "capabilities" and <code>type</code> is "storage" for a block
        device, "misc" for a character device and "net" for a host network
3653
        interface.
3654 3655 3656 3657 3658
      </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
3659 3660
        devices the "char" element is used. For network interfaces, the
        name of the interface is provided in the "interface" element.
3661 3662 3663
      </dd>
    </dl>

3664 3665 3666 3667 3668 3669 3670 3671 3672 3673 3674 3675 3676
    <h4><a name="elementsRedir">Redirected devices</a></h4>

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

<pre>
  ...
  &lt;devices&gt;
    &lt;redirdev bus='usb' type='tcp'&gt;
      &lt;source mode='connect' host='localhost' service='4000'/&gt;
3677
      &lt;boot order='1'/&gt;
3678
    &lt;/redirdev&gt;
3679
    &lt;redirfilter&gt;
3680
      &lt;usbdev class='0x08' vendor='0x1234' product='0xbeef' version='2.56' allow='yes'/&gt;
3681 3682
      &lt;usbdev allow='no'/&gt;
    &lt;/redirfilter&gt;
3683 3684 3685 3686 3687 3688 3689 3690 3691 3692 3693 3694 3695 3696 3697 3698
  &lt;/devices&gt;
  ...</pre>

    <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
J
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3699 3700
        device</a>) are typical. The redirdev element has an optional
        sub-element <code>&lt;address&gt;</code> which can tie the
3701 3702 3703 3704
        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
3705 3706 3707 3708 3709 3710 3711 3712 3713 3714
        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>)
3715 3716 3717 3718
      </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.
J
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3719 3720
        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,
3721
        0x08 represents mass storage devices. The USB device can be addressed by
J
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3722
        vendor / product id using the <code>vendor</code> and <code>product</code> attributes.
3723 3724
        <code>version</code> is the device revision from the bcdDevice field (not
        the version of the USB protocol).
3725
        These four attributes are optional and <code>-1</code> can be used to allow
J
Ján Tomko 已提交
3726
        any value for them. <code>allow</code> attribute is mandatory,
3727 3728
        'yes' means allow, 'no' for deny.
      </dd>
3729 3730
    </dl>

3731 3732 3733 3734 3735 3736 3737 3738 3739 3740 3741 3742 3743 3744 3745 3746 3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757 3758 3759 3760
    <h4><a name="elementsSmartcard">Smartcard devices</a></h4>

    <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>
  ...
  &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;
E
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3761
    &lt;smartcard mode='passthrough' type='spicevmc'/&gt;
3762 3763 3764 3765 3766 3767 3768 3769 3770 3771 3772 3773 3774 3775 3776 3777 3778 3779 3780 3781 3782 3783 3784 3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 3795 3796 3797 3798 3799 3800 3801 3802 3803
  &lt;/devices&gt;
  ...
</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>
      <dt><code>mode='host'</code></dt>
      <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>

      <dt><code>mode='host-certificates'</code></dt>
      <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>

      <dt><code>mode='passthrough'</code></dt>
      <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
3809 3810 3811 3812 3813 3814 3815 3816 3817
      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
3818 3819 3820
      correlation between the smartcard and a ccid bus
      controller, <a href="#elementsAddress">documented above</a>.
      For now, qemu only supports at most one
3821 3822 3823
      smartcard, with an address of bus=0 slot=0.
    </p>

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    <h4><a name="elementsNICS">Network interfaces</a></h4>

3826 3827 3828
<pre>
  ...
  &lt;devices&gt;
3829 3830 3831
    &lt;interface type='direct' trustGuestRxFilters='yes'&gt;
      &lt;source dev='eth0'/&gt;
      &lt;mac address='52:54:00:5d:c7:9e'/&gt;
3832
      &lt;boot order='1'/&gt;
3833
      &lt;rom bar='off'/&gt;
3834 3835 3836
    &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
3841 3842 3843 3844 3845 3846 3847 3848 3849 3850 3851 3852
      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
3854 3855 3856 3857
      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
3860 3861
      attribute <code>type='pci'</code>
      as <a href="#elementsAddress">documented above</a>.
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    </p>

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    <h5><a name="elementsNICSVirtual">Virtual network</a></h5>

    <p>
      <strong><em>
      This is the recommended config for general guest connectivity on
3869 3870 3871 3872
      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>
3877 3878 3879 3880 3881 3882 3883 3884 3885 3886 3887 3888 3889 3890 3891 3892 3893 3894 3895 3896 3897 3898 3899 3900 3901 3902 3903

      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
3904
      <a href="#elementsNICSTargetOverride">overriding the target element</a>).
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    </p>
3906 3907 3908 3909 3910 3911
    <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
3912 3913 3914 3915 3916 3917 3918 3919 3920 3921 3922 3923 3924 3925 3926 3927 3928 3929 3930
      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.
3936 3937 3938
      (<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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      an <code>profileid</code> (in case the switch is 802.1Qbh) and
3940 3941 3942 3943 3944 3945 3946 3947 3948
      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.
3949
    </p>
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3951 3952 3953 3954 3955 3956 3957 3958
<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='network'&gt;
      &lt;source network='default'/&gt;
    &lt;/interface&gt;
    ...
    &lt;interface type='network'&gt;
3959
      &lt;source network='default' portgroup='engineering'/&gt;
3960
      &lt;target dev='vnet7'/&gt;
3961
      &lt;mac address="00:11:22:33:44:55"/&gt;
3962 3963
      &lt;virtualport&gt;
        &lt;parameters instanceid='09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f'/&gt;
3964 3965
      &lt;/virtualport&gt;

3966 3967 3968
    &lt;/interface&gt;
  &lt;/devices&gt;
  ...</pre>
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    <h5><a name="elementsNICSBridge">Bridge to LAN</a></h5>
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    <p>
      <strong><em>
      This is the recommended config for general guest connectivity on
3975
      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
3984 3985 3986 3987 3988
      &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>
3990 3991 3992 3993 3994 3995 3996 3997 3998 3999
    <p>
      On Linux systems, the bridge device is normally a standard Linux
      host bridge. On hosts that support Open vSwitch, it is also
      possible to connect to an open vSwitch bridge device by adding
      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
4001 4002 4003 4004
      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>
4005 4006 4007
<pre>
  ...
  &lt;devices&gt;
4008
    ...
4009 4010 4011 4012
    &lt;interface type='bridge'&gt;
      &lt;source bridge='br0'/&gt;
    &lt;/interface&gt;
    &lt;interface type='bridge'&gt;
4013
      &lt;source bridge='br1'/&gt;
4014
      &lt;target dev='vnet7'/&gt;
4015
      &lt;mac address="00:11:22:33:44:55"/&gt;
4016
    &lt;/interface&gt;
4017 4018
    &lt;interface type='bridge'&gt;
      &lt;source bridge='ovsbr'/&gt;
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      &lt;virtualport type='openvswitch'&gt;
4020 4021 4022 4023
        &lt;parameters profileid='menial' interfaceid='09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f'/&gt;
      &lt;/virtualport&gt;
    &lt;/interface&gt;
    ...
4024
  &lt;/devices&gt;
4025 4026 4027 4028 4029 4030 4031 4032 4033 4034 4035 4036 4037 4038 4039 4040 4041 4042 4043 4044 4045 4046 4047 4048 4049 4050 4051 4052 4053 4054 4055 4056 4057 4058
  ...</pre>

    <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>
  ...
  &lt;devices&gt;
    ...
    &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;
4059
  ...</pre>
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    <h5><a name="elementsNICSSlirp">Userspace SLIRP stack</a></h5>

    <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
      VMs to have outgoing access.
    </p>

4072 4073 4074 4075 4076 4077
<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='user'/&gt;
    ...
    &lt;interface type='user'&gt;
4078
      &lt;mac address="00:11:22:33:44:55"/&gt;
4079 4080 4081
    &lt;/interface&gt;
  &lt;/devices&gt;
  ...</pre>
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    <h5><a name="elementsNICSEthernet">Generic ethernet connection</a></h5>

    <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>

4096 4097 4098 4099 4100 4101 4102 4103 4104 4105 4106
<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='ethernet'/&gt;
    ...
    &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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4108 4109 4110 4111
    <h5><a name="elementsNICSDirect">Direct attachment to physical interface</a></h5>

    <p>
      Provides direct attachment of the virtual machine's NIC to the given
4112
      physical interface of the host.
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      <span class="since">Since 0.7.7 (QEMU and KVM only)</span><br/>
4114 4115 4116
      This setup requires the Linux macvtap
      driver to be available. <span class="since">(Since Linux 2.6.34.)</span>
      One of the modes 'vepa'
4117
      ( <a href="http://www.ieee802.org/1/files/public/docs2009/new-evb-congdon-vepa-modular-0709-v01.pdf">
4118
      'Virtual Ethernet Port Aggregator'</a>), 'bridge' or 'private'
4119
      can be chosen for the operation mode of the macvtap device, 'vepa'
4120 4121
      being the default mode. The individual modes cause the delivery of
      packets to behave as follows:
4122
    </p>
4123 4124 4125 4126 4127 4128 4129 4130 4131 4132 4133 4134
    <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>
4135

4136 4137 4138 4139 4140 4141 4142 4143 4144 4145 4146
    <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,
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      a VEPA capable bridge is required.</dd>
4148 4149 4150 4151 4152 4153
      <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>
4154 4155 4156 4157 4158 4159 4160
      <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>
4161 4162
    </dl>

4163 4164 4165 4166
<pre>
  ...
  &lt;devices&gt;
    ...
4167
    &lt;interface type='direct' trustGuestRxFilters='no'&gt;
4168 4169 4170 4171 4172
      &lt;source dev='eth0' mode='vepa'/&gt;
    &lt;/interface&gt;
  &lt;/devices&gt;
  ...</pre>

4173 4174 4175 4176
    <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.
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    </p>
4178 4179 4180 4181 4182 4183 4184
    <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
4185
      of a virtual machine. <span class="since">Since 0.8.2</span>
4186
    </p>
4187 4188 4189 4190
    <p>
      Please note that IEEE 802.1Qbg requires a non-zero value for the
      VLAN ID.
    </p>
4191 4192 4193 4194 4195 4196 4197 4198 4199 4200 4201 4202 4203 4204 4205 4206 4207 4208 4209 4210 4211 4212 4213 4214 4215
    <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>
  ...
  &lt;devices&gt;
    ...
    &lt;interface type='direct'&gt;
4216
      &lt;source dev='eth0.2' mode='vepa'/&gt;
4217 4218 4219 4220 4221 4222
      &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>
4223

4224 4225 4226 4227 4228 4229 4230 4231 4232
    <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
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        be applied to this interface.  This name is resolved by the port
4234 4235 4236 4237 4238 4239 4240 4241 4242 4243 4244 4245 4246 4247 4248 4249 4250 4251
        profile database into the network parameters from the port profile,
        and those network parameters will be applied to this interface.
      </dd>
    </dl>
  <pre>
  ...
  &lt;devices&gt;
    ...
    &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>

4252 4253 4254 4255 4256 4257 4258 4259

    <h5><a name="elementsNICSHostdev">PCI Passthrough</a></h5>

    <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
4260
      an 802.1Qbh capable switch using an optionally specified
4261
      &lt;virtualport&gt; element (see the examples of virtualport
4262 4263 4264 4265 4266 4267 4268 4269 4270
      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>

4271 4272 4273 4274 4275 4276 4277 4278 4279 4280 4281 4282
    <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>

4283 4284 4285 4286 4287 4288 4289 4290 4291 4292 4293 4294 4295 4296
    <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>

4297 4298 4299 4300 4301 4302
    <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>
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      (or <code>virsh nodedev-detach</code>) before starting the guest
4304 4305 4306 4307 4308
      or hot-plugging the device, and <code>virNodeDeviceReAttach</code>
      (or <code>virsh nodedev-reattach</code>) after hot-unplug or
      stopping the guest.
    </p>

4309 4310 4311
<pre>
  ...
  &lt;devices&gt;
4312
    &lt;interface type='hostdev' managed='yes'&gt;
4313
      &lt;driver name='vfio'/&gt;
4314 4315 4316
      &lt;source&gt;
        &lt;address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/&gt;
      &lt;/source&gt;
4317
      &lt;mac address='52:54:00:6d:90:02'/&gt;
4318 4319 4320 4321 4322 4323 4324 4325
      &lt;virtualport type='802.1Qbh'&gt;
        &lt;parameters profileid='finance'/&gt;
      &lt;/virtualport&gt;
    &lt;/interface&gt;
  &lt;/devices&gt;
  ...</pre>


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4326 4327 4328 4329 4330 4331 4332 4333 4334 4335 4336 4337 4338 4339
    <h5><a name="elementsNICSMulticast">Multicast tunnel</a></h5>

    <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>

4340 4341 4342 4343
<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='mcast'&gt;
4344
      &lt;mac address='52:54:00:6d:90:01'/&gt;
4345 4346 4347 4348
      &lt;source address='230.0.0.1' port='5558'/&gt;
    &lt;/interface&gt;
  &lt;/devices&gt;
  ...</pre>
D
Daniel P. Berrange 已提交
4349 4350 4351 4352 4353 4354 4355 4356 4357 4358 4359 4360

    <h5><a name="elementsNICSTCP">TCP tunnel</a></h5>

    <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>

4361 4362 4363 4364
<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='server'&gt;
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      &lt;mac address='52:54:00:22:c9:42'/&gt;
D
Daniel P. Berrange 已提交
4366
      &lt;source address='192.168.0.1' port='5558'/&gt;
4367 4368 4369
    &lt;/interface&gt;
    ...
    &lt;interface type='client'&gt;
J
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4370
      &lt;mac address='52:54:00:8b:c9:51'/&gt;
4371
      &lt;source address='192.168.0.1' port='5558'/&gt;
4372 4373
    &lt;/interface&gt;
  &lt;/devices&gt;
4374 4375 4376 4377 4378 4379 4380 4381 4382 4383 4384 4385 4386 4387 4388 4389 4390 4391 4392 4393 4394 4395 4396 4397
  ...</pre>

    <h5><a name="elementsNICSUDP">UDP unicast tunnel</a></h5>

    <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>
  ...
  &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;
4398
  ...</pre>
D
Daniel P. Berrange 已提交
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4400 4401
    <h5><a name="elementsNICSModel">Setting the NIC model</a></h5>

4402 4403 4404 4405 4406 4407 4408 4409 4410 4411
<pre>
  ...
  &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>
4412 4413 4414 4415 4416 4417 4418 4419 4420 4421 4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 4433

    <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>
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4435 4436 4437 4438 4439 4440 4441 4442 4443
    <h5><a name="elementsDriverBackendOptions">Setting NIC driver-specific options</a></h5>

<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='network'&gt;
      &lt;source network='default'/&gt;
      &lt;target dev='vnet1'/&gt;
      &lt;model type='virtio'/&gt;
4444
      <b>&lt;driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off' queues='5'&gt;
4445
        &lt;host csum='off' gso='off' tso4='off' tso6='off' ecn='off' ufo='off' mrg_rxbuf='off'/&gt;
4446 4447 4448
        &lt;guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/&gt;
      &lt;/driver&gt;
      </b>
4449 4450 4451 4452 4453 4454 4455 4456 4457 4458 4459 4460
    &lt;/interface&gt;
  &lt;/devices&gt;
  ...</pre>

    <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>
4461 4462 4463 4464 4465 4466 4467 4468 4469 4470 4471 4472
      <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>
4473 4474 4475 4476 4477 4478 4479 4480 4481 4482 4483 4484
      <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>
4485 4486 4487 4488 4489
      <dd>
        For interfaces of type='vhostuser', the <code>name</code>
        attribute is ignored. The backend driver used is always
        vhost-user.
      </dd>
4490

4491 4492 4493 4494 4495
      <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
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        <span class="since">Since 0.8.8 (QEMU and KVM only)</span><br/><br/>
4497 4498 4499 4500

        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
4501
        option).<br/><br/>
4502 4503 4504 4505

        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
4506
        fires, another attempt is made to send more data.<br/><br/>
4507 4508 4509 4510 4511

        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
4512
        cpu where the guest generated the packets."<br/><br/>
4513

4514 4515 4516 4517 4518 4519 4520 4521 4522 4523 4524 4525 4526 4527 4528 4529
        <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/>

4530
        <b>In general you should leave this option alone, unless you
4531 4532 4533 4534 4535 4536
        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'
4537
        - if it is on, it will reduce the number of interrupts and
4538 4539 4540 4541 4542 4543 4544
        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
4545 4546
        are very certain you know what you are doing.</b>
      </dd>
4547 4548
      <dt><code>queues</code></dt>
      <dd>
4549 4550 4551 4552 4553 4554 4555
        The optional <code>queues</code> attribute controls the number
        of queues to be used for either
        <a href="http://www.linux-kvm.org/page/Multiqueue"> Multiqueue
        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
4556
        processor, resulting in much higher throughput.
4557
        <span class="since">virtio-net since 1.0.6 (QEMU and KVM only)</span>
4558
        <span class="since">vhost-user since 1.2.17 (QEMU and KVM only)</span>
4559
      </dd>
4560 4561 4562 4563 4564 4565 4566 4567
      <dt><code>host</code> offloading options</dt>
      <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>
4568 4569 4570 4571
        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>
4572 4573 4574 4575 4576 4577 4578 4579 4580 4581
      </dd>
      <dt><code>guest</code> offloading options</dt>
      <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>
4582 4583
    </dl>

4584 4585 4586 4587 4588 4589 4590 4591 4592
    <h5><a name="elementsBackendOptions">Setting network backend-specific options</a></h5>

<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='network'&gt;
      &lt;source network='default'/&gt;
      &lt;target dev='vnet1'/&gt;
      &lt;model type='virtio'/&gt;
4593
      <b>&lt;backend tap='/dev/net/tun' vhost='/dev/vhost-net'/&gt;</b>
4594 4595 4596 4597 4598 4599 4600
      &lt;driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off' queues='5'/&gt;
    &lt;/interface&gt;
  &lt;/devices&gt;
  ...</pre>

    <p>
      For tuning the backend of the network, the <code>backend</code> element
4601 4602
      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.
4603 4604 4605
      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
      in session mode.
4606
    </p>
4607 4608
    <h5><a name="elementsNICSTargetOverride">Overriding the target element</a></h5>

4609 4610 4611 4612 4613 4614 4615 4616 4617
<pre>
  ...
  &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>
4618 4619

    <p>
E
Eric Blake 已提交
4620 4621
      If no target is specified, certain hypervisors will
      automatically generate a name for the created tun device. This
4622
      name can be manually specified, however the name <i>should not
E
Eric Blake 已提交
4623 4624
      start with either 'vnet' or 'vif'</i>, which are prefixes
      reserved by libvirt and certain hypervisors. Manually specified
4625
      targets using these prefixes may be ignored.
4626 4627
    </p>

4628 4629 4630 4631 4632 4633 4634 4635 4636 4637 4638 4639 4640 4641 4642 4643 4644
    <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>
  ...
  &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>

4645 4646 4647 4648 4649 4650 4651 4652 4653 4654 4655 4656 4657 4658
    <h5><a name="elementsNICSBoot">Specifying boot order</a></h5>

<pre>
  ...
  &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>

    <p>
4659
      For hypervisors which support this, you can set a specific NIC to
4660 4661 4662 4663 4664 4665 4666 4667
      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>

4668 4669 4670 4671 4672 4673 4674 4675
    <h5><a name="elementsNICSROM">Interface ROM BIOS configuration</a></h5>

<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='network'&gt;
      &lt;source network='default'/&gt;
      &lt;target dev='vnet1'/&gt;
4676
      <b>&lt;rom bar='on' file='/etc/fake/boot.bin'/&gt;</b>
4677 4678 4679 4680 4681 4682 4683 4684 4685 4686 4687 4688 4689
    &lt;/interface&gt;
  &lt;/devices&gt;
  ...</pre>

    <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
4690 4691 4692 4693 4694 4695
      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>.
4696
    </p>
4697 4698 4699 4700 4701 4702 4703 4704 4705 4706 4707 4708 4709 4710 4711 4712 4713 4714 4715 4716 4717 4718 4719
    <h5><a name="elementDomain">Setting up a network backend in a driver domain</a></h5>
<pre>
  ...
  &lt;devices&gt;
    ...
    &lt;interface type='bridge'&gt;
      &lt;source bridge='br0'/&gt;
      <b>&lt;backenddomain name='netvm'/&gt;</b>
    &lt;/interface&gt;
    ...
  &lt;/devices&gt;
  ...</pre>

    <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>
4720

4721 4722 4723 4724 4725 4726 4727 4728 4729
    <h5><a name="elementQoS">Quality of service</a></h5>

<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='network'&gt;
      &lt;source network='default'/&gt;
      &lt;target dev='vnet0'/&gt;
      <b>&lt;bandwidth&gt;
4730
        &lt;inbound average='1000' peak='5000' floor='200' burst='1024'/&gt;
4731 4732 4733
        &lt;outbound average='128' peak='256' burst='256'/&gt;
      &lt;/bandwidth&gt;</b>
    &lt;/interface&gt;
M
Michele Paolino 已提交
4734
  &lt;/devices&gt;
4735 4736 4737 4738
  ...</pre>

    <p>
      This part of interface XML provides setting quality of service. Incoming
J
John Ferlan 已提交
4739 4740 4741 4742
      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.
4743 4744
    </p>

4745 4746 4747 4748 4749 4750 4751 4752 4753 4754 4755 4756 4757 4758
    <h5><a name="elementVlanTag">Setting VLAN tag (on supported network types only)</a></h5>

<pre>
  ...
  &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;
4759 4760 4761 4762 4763 4764 4765
    &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;
M
Michele Paolino 已提交
4766
  &lt;/devices&gt;
4767 4768 4769 4770 4771 4772 4773 4774 4775 4776 4777 4778 4779 4780 4781
  ...</pre>

    <p>
      If (and only if) the network connection used by the guest
      supports vlan tagging transparent to the guest, an
      optional <code>&lt;vlan&gt;</code> element can specify one or
      more vlan tags to apply to the guest's network
      traffic <span class="since">Since 0.10.0</span>. (openvswitch
      and type='hostdev' SR-IOV interfaces do support transparent vlan
      tagging of guest traffic; everything else, including standard
      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
      onto specific vlans.) To allow for specification of multiple
      tags (in the case of vlan trunking), a
P
Philipp Hahn 已提交
4782
      subelement, <code>&lt;tag&gt;</code>, specifies which vlan tag
4783 4784 4785 4786 4787 4788 4789 4790 4791
      to use (for example: <code>&lt;tag id='42'/&gt;</code>. If an
      interface has more than one <code>&lt;vlan&gt;</code> element
      defined, it is assumed that the user wants to do VLAN trunking
      using all the specified tags. In the case that vlan trunking
      with a single tag is desired, the optional
      attribute <code>trunk='yes'</code> can be added to the toplevel
      vlan element.
    </p>

4792 4793 4794
    <p>
      For network connections using openvswitch it is possible to
      configure the 'native-tagged' and 'native-untagged' vlan modes
4795
      <span class="since">Since 1.1.0.</span> This uses the optional
4796 4797
      <code>nativeMode</code> attribute on the <code>&lt;tag&gt;</code>
      element: <code>nativeMode</code> may be set to 'tagged' or
4798
      'untagged'. The id attribute of the element sets the native vlan.
4799 4800
    </p>

4801
    <h5><a name="elementLink">Modifying virtual link state</a></h5>
4802 4803 4804 4805 4806 4807 4808 4809
<pre>
  ...
  &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;
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4810
  &lt;/devices&gt;
4811 4812 4813 4814 4815 4816 4817 4818 4819 4820 4821
  ...</pre>

    <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>

4822 4823 4824 4825 4826 4827 4828
    <h5><a name="ipconfig">IP configuration</a></h5>
<pre>
  ...
  &lt;devices&gt;
    &lt;interface type='network'&gt;
      &lt;source network='default'/&gt;
      &lt;target dev='vnet0'/&gt;
4829
      <b>&lt;ip address='192.168.122.5' prefix='24'/&gt;</b>
4830
      <b>&lt;ip address='192.168.122.5' prefix='24' peer='10.0.0.10'/&gt;</b>
4831
      <b>&lt;route family='ipv4' address='192.168.122.0' prefix='24' gateway='192.168.122.1'/&gt;</b>
4832
      <b>&lt;route family='ipv4' address='192.168.122.8' gateway='192.168.122.1'/&gt;</b>
4833
    &lt;/interface&gt;
4834 4835 4836 4837 4838
    ...
    &lt;hostdev mode='capabilities' type='net'&gt;
      &lt;source&gt;
        &lt;interface&gt;eth0&lt;/interface&gt;
      &lt;/source&gt;
4839
      <b>&lt;ip address='192.168.122.6' prefix='24'/&gt;</b>
4840
      <b>&lt;route family='ipv4' address='192.168.122.0' prefix='24' gateway='192.168.122.1'/&gt;</b>
4841
      <b>&lt;route family='ipv4' address='192.168.122.8' gateway='192.168.122.1'/&gt;</b>
4842 4843
    &lt;/hostdev&gt;

4844 4845 4846 4847 4848 4849 4850 4851 4852 4853 4854 4855 4856 4857
  &lt;/devices&gt;
  ...
</pre>

    <p>
    <span class="since">Since 1.2.12</span> the network devices and host devices
    with network capabilities can be provided zero or more IP addresses to set
    on the target device. 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>, the
    <code>address</code> attribute holds the IP address. The <code>prefix</code>
    is not mandatory since some hypervisors do not handle it.
    </p>

4858 4859
    <p>
    <span class="since">Since 1.2.12</span> route elements can also be added
4860 4861 4862
    to define the network routes to use for the network device. 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>.
4863 4864 4865 4866 4867 4868 4869 4870 4871 4872
    This is used by the LXC driver and <span class="since">Since 1.3.3</span> by the QEMU
    driver.
    </p>

    <p>
    <span class="since">Since 1.3.3</span> ip elements can hold peer attribute to assign
    a point-to-point address for the network device. The attributes  of this element
    are described in the documentation for the <code>ip</code> element in
    <a href="formatnetwork.html#elementsAddress">network definitions</a>.
    This is only used by the LXC and QEMU drivers.
4873 4874
    </p>

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    <h5><a name="elementVhostuser">vhost-user interface</a></h5>

    <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>
  ...
  &lt;devices&gt;
    &lt;interface type='vhostuser'&gt;
      &lt;mac address='52:54:00:3b:83:1a'/&gt;
4889
      &lt;source type='unix' path='/tmp/vhost1.sock' mode='server'/&gt;
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4890 4891
      &lt;model type='virtio'/&gt;
    &lt;/interface&gt;
4892 4893 4894 4895 4896 4897
    &lt;interface type='vhostuser'&gt;
      &lt;mac address='52:54:00:3b:83:1b'/&gt;
      &lt;source type='unix' path='/tmp/vhost2.sock' mode='client'/&gt;
      &lt;model type='virtio'/&gt;
      &lt;driver queues='5'/&gt;
    &lt;/interface&gt;
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4898 4899 4900 4901 4902 4903 4904 4905 4906 4907 4908 4909 4910 4911
  &lt;/devices&gt;
  ...</pre>

    <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.
    </p>

4912 4913 4914 4915 4916 4917 4918 4919 4920 4921 4922 4923 4924 4925 4926 4927 4928 4929 4930 4931 4932 4933 4934 4935 4936 4937 4938 4939 4940 4941 4942 4943 4944 4945 4946 4947 4948 4949 4950 4951
    <h5><a name="elementNwfilter">Traffic filtering with NWFilter</a></h5>

    <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>
  ...
  &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;
        ...
      &lt;/filterref&gt;
    &lt;/interface&gt;
  &lt;/devices&gt;
  ...</pre>

    <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>


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    <h4><a name="elementsInput">Input devices</a></h4>

    <p>
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4955 4956 4957 4958
      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,
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4959 4960 4961
      to provide a graphics tablet for absolute cursor movement.
    </p>

4962 4963 4964 4965
<pre>
  ...
  &lt;devices&gt;
    &lt;input type='mouse' bus='usb'/&gt;
4966
    &lt;input type='keyboard' bus='usb'/&gt;
4967 4968 4969
    &lt;input type='mouse' bus='virtio'/&gt;
    &lt;input type='keyboard' bus='virtio'/&gt;
    &lt;input type='tablet' bus='virtio'/&gt;
4970 4971 4972
    &lt;input type='passthrough' bus='virtio'&gt;
      &lt;source evdev='/dev/input/event1/&gt;
    &lt;/input&gt;
4973 4974
  &lt;/devices&gt;
  ...</pre>
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4975 4976 4977

    <dl>
      <dt><code>input</code></dt>
E
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4978
      <dd>The <code>input</code> element has one mandatory attribute,
4979 4980 4981
        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'.
4982 4983
        The tablet provides absolute cursor movement,
        while the mouse uses relative movement. The optional
M
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4984
        <code>bus</code> attribute can be used to refine the exact device type.
4985 4986
        It takes values "xen" (paravirtualized), "ps2" and "usb" or
        (<span class="since">since 1.3.0</span>) "virtio".</dd>
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4987 4988
    </dl>

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4989 4990 4991
    <p>
      The <code>input</code> element has an optional
      sub-element <code>&lt;address&gt;</code> which can tie the
4992 4993
      device to a particular PCI
      slot, <a href="#elementsAddress">documented above</a>.
4994 4995 4996 4997

      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)
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4998
    </p>
D
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4999

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5000 5001 5002 5003 5004 5005 5006 5007 5008 5009 5010 5011 5012 5013 5014 5015 5016 5017 5018 5019 5020 5021 5022
    <h4><a name="elementsHub">Hub devices</a></h4>

    <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>
  ...
  &lt;devices&gt;
    &lt;hub type='usb'/&gt;
  &lt;/devices&gt;
  ...</pre>

    <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
5023 5024 5025 5026
      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>.
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5027 5028
    </p>

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5029 5030 5031 5032 5033 5034 5035 5036 5037
    <h4><a name="elementsGraphics">Graphical framebuffers</a></h4>

    <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>

5038 5039 5040 5041
<pre>
  ...
  &lt;devices&gt;
    &lt;graphics type='sdl' display=':0.0'/&gt;
5042
    &lt;graphics type='vnc' port='5904' sharePolicy='allow-exclusive'&gt;
5043 5044
      &lt;listen type='address' address='1.2.3.4'/&gt;
    &lt;/graphics&gt;
5045 5046
    &lt;graphics type='rdp' autoport='yes' multiUser='yes' /&gt;
    &lt;graphics type='desktop' fullscreen='yes'/&gt;
5047 5048 5049
    &lt;graphics type='spice'&gt;
      &lt;listen type='network' network='rednet'/&gt;
    &lt;/graphics&gt;
5050 5051
  &lt;/devices&gt;
  ...</pre>
D
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5052 5053 5054

    <dl>
      <dt><code>graphics</code></dt>
5055 5056 5057 5058 5059 5060
      <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>
5061 5062 5063
        <dl>
          <dt><code>"sdl"</code></dt>
          <dd>
5064 5065 5066 5067 5068 5069 5070
            <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>
5071 5072 5073
          </dd>
          <dt><code>"vnc"</code></dt>
          <dd>
5074 5075 5076 5077 5078 5079 5080 5081 5082 5083 5084 5085 5086 5087 5088 5089 5090 5091 5092 5093 5094 5095 5096 5097 5098 5099 5100 5101 5102 5103 5104 5105 5106 5107 5108 5109 5110 5111
            <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
              port to use. The <code>listen</code> attribute is an IP address
              for the server to listen on. The <code>passwd</code> attribute
              provides a VNC password in clear text. 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 an timestamp
              <code>passwdValidTo='2010-04-09T15:51:00'</code> assumed to be
              in UTC. The <code>connected</code> attribute allows control of
              connected client during password changes. VNC accepts
              <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>
5112
          </dd>
5113
          <dt><code>"spice"</code> <span class="since">Since 0.8.6</span></dt>
5114
          <dd>
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5115
            <p>
5116 5117 5118 5119 5120 5121 5122 5123 5124 5125 5126 5127 5128 5129 5130 5131 5132 5133 5134 5135
              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
              auto-allocation of needed port numbers. The <code>listen</code>
              attribute is an IP address for the server to listen on.
              The <code>passwd</code> attribute provides a SPICE password in
              clear text. 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 an timestamp
              <code>passwdValidTo='2010-04-09T15:51:00'</code> assumed to be in
              UTC.
            </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.
5136
              <span class="since">Since 0.9.3</span>
5137 5138
            </p>
            <p>
5139 5140
              The <code>defaultMode</code> attribute sets the default channel
              security policy, valid values are <code>secure</code>,
5141 5142 5143 5144
              <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>
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5145 5146
            </p>
            <p>
5147 5148 5149 5150 5151 5152 5153 5154
              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
5155
              <code>any</code> as mode discards the entry as the channel would
5156 5157 5158
              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>
5159
              (all <span class="since"> since 0.8.6</span>);
5160 5161
              <code>smartcard</code> (<span class="since">since 0.8.8</span>);
              and <code>usbredir</code> (<span class="since">since 0.9.12</span>).
E
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5162 5163
            </p>
            <pre>
5164 5165 5166
  &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;
5167
    &lt;image compression='auto_glz'/&gt;
5168
    &lt;streaming mode='filter'/&gt;
5169
    &lt;clipboard copypaste='no'/&gt;
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5170
    &lt;mouse mode='client'/&gt;
5171
    &lt;filetransfer enable='no'/&gt;
5172
    &lt;gl enable='yes'/&gt;
5173
  &lt;/graphics&gt;</pre>
5174
            <p>
5175 5176 5177 5178 5179 5180 5181 5182 5183 5184 5185 5186
              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>
5187
            </p>
5188
            <p>
5189 5190 5191 5192
              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>
5193
            </p>
5194
            <p>
5195 5196 5197 5198
              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>
5199
            </p>
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5200
            <p>
5201 5202 5203 5204
              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>
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5205
            </p>
5206 5207
            <p>
              File transfer functionality (via Spice agent) is set using the
5208 5209 5210
              <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>
5211
            </p>
5212
            <p>
5213 5214 5215 5216
              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>
              property. (QEMU only, <span class="since">since 1.3.2</span>).
5217
            </p>
5218 5219 5220
          </dd>
          <dt><code>"rdp"</code></dt>
          <dd>
5221 5222 5223 5224 5225 5226 5227 5228 5229 5230 5231 5232
            <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
              use. The <code>replaceUser</code> attribute is a boolean deciding
              whether multiple simultaneous connections to the VM are permitted.
              The <code>multiUser</code> attribute is a boolean deciding whether
              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>
5233 5234 5235
          </dd>
          <dt><code>"desktop"</code></dt>
          <dd>
5236 5237 5238 5239 5240 5241 5242
            <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>
5243 5244 5245 5246 5247
          </dd>
        </dl>
      </dd>
    </dl>

5248
    <p>
5249 5250 5251 5252 5253 5254
      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:
5255 5256 5257
    </p>
    <dl>
      <dt><code>address</code></dt>
5258 5259 5260 5261 5262 5263 5264
      <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>
5265 5266
      </dd>
      <dt><code>network</code></dt>
5267 5268 5269 5270 5271 5272 5273 5274 5275 5276 5277 5278 5279 5280 5281
      <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>
5282 5283 5284
      </dd>
    </dl>

5285 5286 5287 5288 5289
    <h4><a name="elementsVideo">Video devices</a></h4>
    <p>
      A video device.
    </p>

5290 5291 5292 5293
<pre>
  ...
  &lt;devices&gt;
    &lt;video&gt;
5294
      &lt;model type='vga' vram='16384' heads='1'&gt;
5295
        &lt;acceleration accel3d='yes' accel2d='yes'/&gt;
5296 5297 5298 5299
      &lt;/model&gt;
    &lt;/video&gt;
  &lt;/devices&gt;
  ...</pre>
5300 5301 5302

    <dl>
      <dt><code>video</code></dt>
5303
      <dd>
5304 5305 5306 5307 5308 5309 5310 5311 5312 5313 5314 5315 5316 5317 5318 5319
        <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
          video device. The non-primary must be type of "qxl".
        </p>
5320
      </dd>
5321

5322 5323
      <dt><code>model</code></dt>
      <dd>
5324 5325 5326
        <p>
          The <code>model</code> element has a mandatory <code>type</code>
          attribute which takes the value "vga", "cirrus", "vmvga", "xen",
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          "vbox", "qxl" (<span class="since">since 0.8.6</span>) or
          "virtio" (<span class="since">since 1.3.0</span>)
          depending on the hypervisor features available.
5330 5331 5332 5333
        </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
5334
          type of "libxl", "vz", "qemu", "vbox", "vmx" and "xen". If no
5335 5336 5337 5338 5339
          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
5340
          supported only for guests type of "vz", "kvm", "vbox" and "vmx".
5341 5342
        </p>
        <p>
5343 5344 5345
          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
5346
          attribute <code>vram</code> specifies the secondary bar size.
5347 5348 5349 5350 5351
          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.
5352
          Attribute <code>vram64</code> (<span class="since">since 1.3.3</span>)
5353
          extends secondary bar and makes it addressable as 64bit memory.
5354
        </p>
5355 5356 5357 5358
      </dd>

      <dt><code>acceleration</code></dt>
      <dd>
5359 5360 5361 5362 5363 5364 5365 5366 5367 5368 5369
        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>
5370
      </dd>
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      <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.
      </dd>
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    </dl>

5379
    <h4><a name="elementsConsole">Consoles, serial, parallel &amp; channel devices</a></h4>
D
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    <p>
      A character device provides a way to interact with the virtual machine.
5383 5384
      Paravirtualized consoles, serial ports, parallel ports and channels are
      all classed as character devices and so represented using the same syntax.
D
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5385 5386
    </p>

5387 5388 5389 5390 5391 5392 5393 5394 5395 5396 5397
<pre>
  ...
  &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;
5398
    &lt;serial type='file'&gt;
5399
      &lt;source path='/tmp/file' append='on'&gt;
5400 5401
        &lt;seclabel model='dac' relabel='no'/&gt;
      &lt;/source&gt;
5402
      &lt;target port='0'/&gt;
5403
    &lt;/serial&gt;
5404 5405 5406 5407 5408 5409 5410 5411 5412 5413
    &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>
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5414

5415 5416 5417 5418 5419
    <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
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5420

5421 5422 5423 5424 5425 5426
    <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>

5427 5428 5429 5430 5431 5432 5433 5434
    <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>

5435 5436 5437 5438 5439 5440 5441 5442
    <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>

5443
    <p>
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Boris Fiuczynski 已提交
5444
      Regardless of the <code>type</code>, character devices can
5445 5446
      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
5447 5448 5449
      <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>.
5450 5451 5452 5453 5454 5455 5456
    </p>

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

E
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5457 5458 5459 5460 5461 5462 5463 5464
    <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>

5465 5466 5467 5468 5469 5470 5471 5472 5473
    <h5><a name="elementsCharGuestInterface">Guest interface</a></h5>

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

    <h6><a name="elementCharParallel">Parallel port</a></h6>

5474 5475 5476 5477 5478 5479 5480 5481 5482
<pre>
  ...
  &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>
5483 5484 5485

    <p>
      <code>target</code> can have a <code>port</code> attribute, which
5486
      specifies the port number. Ports are numbered starting from 0. There are
5487 5488 5489 5490 5491
      usually 0, 1 or 2 parallel ports.
    </p>

    <h6><a name="elementCharSerial">Serial port</a></h6>

5492 5493 5494 5495 5496 5497 5498 5499 5500
<pre>
  ...
  &lt;devices&gt;
    &lt;serial type='pty'&gt;
      &lt;source path='/dev/pts/3'/&gt;
      &lt;target port='0'/&gt;
    &lt;/serial&gt;
  &lt;/devices&gt;
  ...</pre>
5501 5502 5503

    <p>
      <code>target</code> can have a <code>port</code> attribute, which
5504
      specifies the port number. Ports are numbered starting from 0. There are
G
Guannan Ren 已提交
5505 5506
      usually 0, 1 or 2 serial ports. There is also an optional
      <code>type</code> attribute <span class="since">since 1.0.2</span>
M
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5507 5508 5509 5510 5511 5512 5513 5514 5515 5516
      which has three choices for its value, one is <code>isa-serial</code>,
      then <code>usb-serial</code> and last one is <code>pci-serial</code>.
      If <code>type</code> is missing, <code>isa-serial</code> will be used by
      default. For <code>usb-serial</code> an optional sub-element
      <code>&lt;address/&gt;</code> with <code>type='usb'</code> can tie the
      device to a particular controller, <a href="#elementsAddress">documented above</a>.
      Similarly, <code>pci-serial</code> can be used to attach the device to
      the pci bus (<span class="since">since 1.2.16</span>). Again, it has
      optional sub-element <code>&lt;address/&gt;</code> with
      <code>type='pci'</code> to select desired location on the PCI bus.
5517 5518 5519 5520 5521
    </p>

    <h6><a name="elementCharConsole">Console</a></h6>

    <p>
5522 5523 5524 5525 5526 5527 5528
      The console element is used to represent interactive consoles. Depending
      on the type of guest in use, the consoles might be paravirtualized devices,
      or they might be a clone of a serial device, according to the following
      rules:
    </p>

    <ul>
5529
      <li>If no <code>targetType</code> attribute is set, then the default
5530 5531 5532 5533 5534 5535 5536 5537 5538 5539 5540 5541 5542
        device type is according to the hypervisor's rules. The default
        type will be added when re-querying the XML fed into libvirt.
        For fully virtualized guests, the default device type will usually
        be a serial port.</li>
      <li>If the <code>targetType</code> attribute is <code>serial</code>,
        then if no <code>&lt;serial&gt;</code> element exists, the console
        element will be copied to the serial element. If a <code>&lt;serial&gt;</code>
        element does already exist, the console element will be ignored.</li>
      <li>If the <code>targetType</code> attribute is not <code>serial</code>,
        it will be treated normally.</li>
      <li>Only the first <code>console</code> element may use a <code>targetType</code>
        of <code>serial</code>. Secondary consoles must all be paravirtualized.
      </li>
5543 5544 5545 5546 5547 5548
      <li>On s390, the <code>console</code> element may use a
        <code>targetType</code> of <code>sclp</code> or <code>sclplm</code>
        (line mode). SCLP is the native console type for s390. There's no
        controller associated to SCLP consoles.
        <span class="since">Since 1.0.2</span>
      </li>
5549
    </ul>
C
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5550 5551 5552 5553 5554 5555

    <p>
      A virtio console device is exposed in the
      guest as /dev/hvc[0-7] (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>
5556 5557
    </p>

5558 5559 5560 5561 5562 5563 5564
<pre>
  ...
  &lt;devices&gt;
    &lt;console type='pty'&gt;
      &lt;source path='/dev/pts/4'/&gt;
      &lt;target port='0'/&gt;
    &lt;/console&gt;
C
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5565 5566 5567 5568 5569 5570

    &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;
5571 5572
  &lt;/devices&gt;
  ...</pre>
5573

5574 5575 5576 5577 5578 5579 5580 5581 5582 5583 5584
<pre>
  ...
  &lt;devices&gt;
    &lt;!-- KVM s390 sclp console --&gt;
    &lt;console type='pty'&gt;
      &lt;source path='/dev/pts/1'/&gt;
      &lt;target type='sclp' port='0'/&gt;
    &lt;/console&gt;
  &lt;/devices&gt;
  ...</pre>

5585 5586 5587 5588 5589 5590
    <p>
      If the console is presented as a serial port, the <code>target</code>
      element has the same attributes as for a serial port. There is usually
      only 1 console.
    </p>

5591 5592 5593 5594 5595 5596 5597
    <h6><a name="elementCharChannel">Channel</a></h6>

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

5598 5599 5600 5601 5602 5603 5604
<pre>
  ...
  &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;
5605 5606 5607 5608 5609

    &lt;!-- KVM virtio channel --&gt;
    &lt;channel type='pty'&gt;
      &lt;target type='virtio' name='arbitrary.virtio.serial.port.name'/&gt;
    &lt;/channel&gt;
D
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5610 5611
    &lt;channel type='unix'&gt;
      &lt;source mode='bind' path='/var/lib/libvirt/qemu/f16x86_64.agent'/&gt;
5612
      &lt;target type='virtio' name='org.qemu.guest_agent.0' state='connected'/&gt;
D
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5613
    &lt;/channel&gt;
5614 5615 5616
    &lt;channel type='spicevmc'&gt;
      &lt;target type='virtio' name='com.redhat.spice.0'/&gt;
    &lt;/channel&gt;
5617 5618
  &lt;/devices&gt;
  ...</pre>
5619 5620 5621 5622 5623 5624 5625 5626 5627 5628 5629 5630 5631 5632

    <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>
5633 5634 5635

      <dt><code>virtio</code></dt>
      <dd>Paravirtualized virtio channel. Channel is exposed in the guest under
E
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5636
        /dev/vport*, and if the optional element <code>name</code> is specified,
5637
        /dev/virtio-ports/$name (for more info, please see
E
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5638 5639
        <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
5640 5641
        particular <code>type='virtio-serial'</code>
        controller, <a href="#elementsAddress">documented above</a>.
D
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5642 5643 5644 5645
        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
5646
        since 0.9.10</span> Moreover, <span class="since">since 1.0.6</span>
5647 5648 5649 5650
        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
5651 5652 5653 5654 5655 5656
        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>.
5657
      </dd>
5658 5659 5660 5661 5662 5663 5664 5665 5666 5667 5668 5669 5670
      <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>
5671 5672
    </dl>

5673 5674 5675 5676 5677 5678
    <h5><a name="elementsCharHostInterface">Host interface</a></h5>

    <p>
      A character device presents itself to the host as one of the following
      types.
    </p>
D
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5679

5680
    <h6><a name="elementsCharSTDIO">Domain logfile</a></h6>
D
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5681 5682 5683 5684 5685 5686

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

5687 5688 5689 5690
<pre>
  ...
  &lt;devices&gt;
    &lt;console type='stdio'&gt;
E
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5691
      &lt;target port='1'/&gt;
5692 5693 5694
    &lt;/console&gt;
  &lt;/devices&gt;
  ...</pre>
D
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5695 5696


5697
    <h6><a name="elementsCharFle">Device logfile</a></h6>
D
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5698 5699 5700 5701 5702 5703

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

5704 5705 5706 5707 5708 5709 5710 5711 5712
<pre>
  ...
  &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
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5713

5714
    <h6><a name="elementsCharVC">Virtual console</a></h6>
D
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5715 5716 5717 5718 5719 5720 5721

    <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>

5722 5723 5724 5725 5726 5727 5728 5729
<pre>
  ...
  &lt;devices&gt;
    &lt;serial type='vc'&gt;
      &lt;target port="1"/&gt;
    &lt;/serial&gt;
  &lt;/devices&gt;
  ...</pre>
D
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5730

5731
    <h6><a name="elementsCharNull">Null device</a></h6>
D
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5732 5733 5734 5735 5736 5737

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

5738 5739 5740 5741 5742 5743 5744 5745
<pre>
  ...
  &lt;devices&gt;
    &lt;serial type='null'&gt;
      &lt;target port="1"/&gt;
    &lt;/serial&gt;
  &lt;/devices&gt;
  ...</pre>
D
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5746

5747
    <h6><a name="elementsCharPTY">Pseudo TTY</a></h6>
D
Daniel P. Berrange 已提交
5748 5749 5750 5751 5752 5753 5754

    <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>

5755 5756 5757 5758 5759 5760 5761 5762 5763
<pre>
  ...
  &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
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5764 5765 5766

    <p>
      NB special case if &lt;console type='pty'&gt;, then the TTY
A
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5767
      path is also duplicated as an attribute tty='/dev/pts/3'
D
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5768 5769 5770 5771
      on the top level &lt;console&gt; tag. This provides compat
      with existing syntax for &lt;console&gt; tags.
    </p>

5772
    <h6><a name="elementsCharHost">Host device proxy</a></h6>
D
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5773 5774 5775 5776 5777

    <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
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5778
      a host serial port - don't connect a serial port to a parallel
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5779 5780 5781
      port.
    </p>

5782 5783 5784 5785 5786 5787
<pre>
  ...
  &lt;devices&gt;
    &lt;serial type="dev"&gt;
      &lt;source path="/dev/ttyS0"/&gt;
      &lt;target port="1"/&gt;
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5788
    &lt;/serial&gt;
5789 5790
  &lt;/devices&gt;
  ...</pre>
D
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5791

5792
    <h6><a name="elementsCharPipe">Named pipe</a></h6>
5793 5794 5795 5796 5797 5798

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

5799 5800 5801 5802 5803 5804 5805 5806 5807
<pre>
  ...
  &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>
5808

5809
    <h6><a name="elementsCharTCP">TCP client/server</a></h6>
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5810 5811 5812

    <p>
      The character device acts as a TCP client connecting to a
5813
      remote server.
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5814 5815
    </p>

5816 5817 5818 5819 5820 5821 5822 5823 5824 5825
<pre>
  ...
  &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>
5826 5827 5828 5829 5830

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

5831 5832 5833 5834 5835 5836 5837 5838 5839 5840
<pre>
  ...
  &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>
5841 5842

    <p>
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5843 5844 5845
      Alternatively you can use <code>telnet</code> instead
      of <code>raw</code> TCP.  <span class="since">Since 0.8.5</span>
      you can also use <code>telnets</code>
5846
      (secure telnet) and <code>tls</code>.
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5847
    </p>
5848

5849 5850 5851 5852 5853 5854 5855 5856 5857 5858 5859 5860 5861 5862 5863 5864
<pre>
  ...
  &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;
    ...
    &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>
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5865

5866
    <h6><a name="elementsCharUDP">UDP network console</a></h6>
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5867 5868 5869 5870 5871 5872

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

5873 5874 5875 5876 5877 5878 5879 5880 5881 5882
<pre>
  ...
  &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>
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5883

5884
    <h6><a name="elementsCharUNIX">UNIX domain socket client/server</a></h6>
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5885 5886 5887 5888 5889 5890

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

5891 5892 5893 5894 5895 5896 5897 5898 5899
<pre>
  ...
  &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>
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5900

5901 5902 5903 5904 5905 5906 5907
    <h6><a name="elementsCharSpiceport">Spice channel</a></h6>

    <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>
5908 5909 5910 5911 5912
    <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>
5913 5914 5915 5916 5917 5918 5919 5920 5921 5922 5923

<pre>
  ...
  &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>

5924 5925 5926 5927
    <h6><a name="elementsNmdm">Nmdm device</a></h6>

    <p>
      The nmdm device driver, available on FreeBSD, provides two
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      tty devices connected together by a virtual null modem cable.
5929 5930 5931 5932 5933 5934 5935 5936 5937 5938 5939 5940 5941 5942 5943 5944 5945 5946
      <span class="since">Since 1.2.4</span>
    </p>

<pre>
  ...
  &lt;devices&gt;
    &lt;serial type="nmdm"&gt;
      &lt;source master="/dev/nmdm0A" slave="/dev/nmdm0B"/&gt;
    &lt;/serial&gt;
  &lt;/devices&gt;
  ...</pre>

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

    <dl>
      <dt><code>master</code></dt>
5947 5948
      <dd>Master device of the pair, that is passed to the hypervisor.
      Device is specified by a fully qualified path.</dd>
5949 5950 5951

      <dt><code>slave</code></dt>
      <dd>Slave device of the pair, that is passed to the clients for connection
5952
      to the guest console. Device is specified by a fully qualified path.</dd>
5953
    </dl>
5954 5955 5956 5957 5958 5959 5960 5961

    <h4><a name="elementsSound">Sound devices</a></h4>

    <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>

5962 5963 5964 5965 5966 5967
<pre>
  ...
  &lt;devices&gt;
    &lt;sound model='es1370'/&gt;
  &lt;/devices&gt;
  ...</pre>
5968 5969 5970 5971 5972 5973 5974

    <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
5975
        choices are 'es1370', 'sb16', 'ac97', 'ich6' and 'usb'.
5976
        (<span class="since">
5977 5978
         'ac97' only since 0.6.0, 'ich6' only since 0.8.8,
         'usb' only since 1.2.7</span>)
5979 5980 5981
      </dd>
    </dl>

5982 5983 5984 5985 5986 5987 5988 5989 5990 5991 5992 5993 5994 5995 5996
    <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
      will be attached to allow playback and recording. Valid values
      are 'duplex' (advertise a line-in and a line-out) and 'micro'
      (advertise a speaker and a microphone).
    </p>

<pre>
  ...
  &lt;devices&gt;
    &lt;sound model='ich6'&gt;
      &lt;codec type='micro'/&gt;
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    &lt;/sound&gt;
5998 5999 6000
  &lt;/devices&gt;
  ...</pre>

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    <p>
      Each <code>sound</code> element has an optional
      sub-element <code>&lt;address&gt;</code> which can tie the
6004 6005
      device to a particular PCI
      slot, <a href="#elementsAddress">documented above</a>.
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6006 6007
    </p>

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    <h4><a name="elementsWatchdog">Watchdog device</a></h4>

    <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>

6028 6029 6030 6031 6032 6033
<pre>
  ...
  &lt;devices&gt;
    &lt;watchdog model='i6300esb'/&gt;
  &lt;/devices&gt;
  ...</pre>
R
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6034

6035 6036 6037 6038 6039 6040
<pre>
  ...
  &lt;devices&gt;
    &lt;watchdog model='i6300esb' action='poweroff'/&gt;
  &lt;/devices&gt;
&lt;/domain&gt;</pre>
R
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6041 6042 6043 6044

    <dl>
      <dt><code>model</code></dt>
      <dd>
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        <p>
R
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        The required <code>model</code> attribute specifies what real
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        watchdog device is emulated.  Valid values are specific to the
        underlying hypervisor.
        </p>
        <p>
        QEMU and KVM support:
        </p>
        <ul>
          <li> 'i6300esb' &mdash; the recommended device,
            emulating a PCI Intel 6300ESB </li>
          <li> 'ib700' &mdash; emulating an ISA iBase IB700 </li>
6057
          <li> 'diag288' &mdash; emulating an S390 DIAG288 device
6058
            <span class="since">Since 1.2.17</span></li>
M
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6059
        </ul>
R
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6060 6061 6062
      </dd>
      <dt><code>action</code></dt>
      <dd>
M
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6063
        <p>
R
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6064
        The optional <code>action</code> attribute describes what
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        action to take when the watchdog expires.  Valid values are
        specific to the underlying hypervisor.
        </p>
        <p>
        QEMU and KVM support:
        </p>
        <ul>
          <li>'reset' &mdash; default, forcefully reset the guest</li>
          <li>'shutdown' &mdash; gracefully shutdown the guest
            (not recommended) </li>
          <li>'poweroff' &mdash; forcefully power off the guest</li>
          <li>'pause' &mdash; pause the guest</li>
          <li>'none' &mdash; do nothing</li>
6078 6079
          <li>'dump' &mdash; automatically dump the guest
            <span class="since">Since 0.8.7</span></li>
6080 6081
          <li>'inject-nmi' &mdash; inject a non-maskable interrupt
            into the guest
6082
            <span class="since">Since 1.2.17</span></li>
M
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6083 6084
        </ul>
        <p>
6085
        Note 1: the 'shutdown' action requires that the guest
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6086 6087 6088 6089 6090
        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>
6091 6092 6093 6094
        <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
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6095 6096 6097
      </dd>
    </dl>

6098 6099 6100 6101 6102 6103 6104 6105 6106
    <h4><a name="elementsMemBalloon">Memory balloon device</a></h4>

    <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>
6107 6108 6109
      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.
6110 6111 6112
    </p>

    <p>
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6113
      Example: automatically added device with KVM
6114 6115 6116 6117 6118 6119 6120 6121 6122
    </p>
<pre>
  ...
  &lt;devices&gt;
    &lt;memballoon model='virtio'/&gt;
  &lt;/devices&gt;
  ...</pre>

    <p>
J
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6123
      Example: manually added device with static PCI slot 2 requested
6124 6125 6126 6127
    </p>
<pre>
  ...
  &lt;devices&gt;
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6128 6129
    &lt;memballoon model='virtio'&gt;
      &lt;address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/&gt;
6130
      &lt;stats period='10'/&gt;
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    &lt;/memballoon&gt;
6132 6133 6134 6135 6136 6137 6138 6139
  &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
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          of balloon device is provided. Valid values are specific to
          the virtualization platform
6142 6143 6144 6145 6146 6147
        </p>
        <ul>
          <li>'virtio' &mdash; default with QEMU/KVM</li>
          <li>'xen' &mdash; default with Xen</li>
        </ul>
      </dd>
6148 6149 6150 6151 6152 6153 6154 6155 6156 6157
      <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>
6158 6159 6160
      <dt><code>period</code></dt>
      <dd>
        <p>
6161 6162 6163 6164 6165 6166 6167 6168 6169 6170 6171
          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.
6172 6173 6174
          <span class='since'>Since 1.1.1, requires QEMU 1.5</span>
        </p>
      </dd>
6175
    </dl>
6176 6177 6178 6179 6180 6181 6182 6183 6184 6185 6186 6187 6188 6189 6190
    <h4><a name="elementsRng">Random number generator device</a></h4>

    <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>
  ...
  &lt;devices&gt;
    &lt;rng model='virtio'&gt;
6191
      &lt;rate period="2000" bytes="1234"/&gt;
6192 6193 6194
      &lt;backend model='random'&gt;/dev/random&lt;/backend&gt;
      &lt;!-- OR --&gt;
      &lt;backend model='egd' type='udp'&gt;
6195 6196
        &lt;source mode='bind' service='1234'/&gt;
        &lt;source mode='connect' host='1.2.3.4' service='1234'/&gt;
6197 6198 6199 6200 6201 6202 6203 6204 6205 6206 6207 6208 6209 6210 6211 6212 6213
      &lt;/backend&gt;
    &lt;/rng&gt;
  &lt;/devices&gt;
  ...
</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>
          <li>'virtio' &mdash; supported by qemu and virtio-rng kernel module</li>
        </ul>
      </dd>
6214 6215 6216 6217 6218 6219 6220 6221 6222 6223 6224 6225
      <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>
6226 6227 6228 6229 6230 6231 6232 6233
      <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>
        <ul>
6234 6235
          <li>'random' &mdash; /dev/random (default) or /dev/hwrng
            device as source (for now, no other sources are permitted)</li>
6236 6237 6238
          <li>'egd' &mdash; a EGD protocol backend</li>
        </ul>
      </dd>
6239
      <dt><code>backend model='random'</code></dt>
6240 6241 6242
      <dd>
        <p>
          This backend type expects a non-blocking character device as input.
6243
          The only accepted paths are /dev/random and /dev/hwrng. The file
6244 6245 6246 6247
          name is specified as contents of the <code>backend</code> element.
          When no file name is specified the hypervisor default is used.
        </p>
      </dd>
6248
      <dt><code>backend model='egd'</code></dt>
6249 6250 6251 6252 6253 6254 6255 6256 6257 6258
      <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>
6259

6260 6261 6262 6263 6264 6265 6266 6267
    <h4><a name="elementsTpm">TPM device</a></h4>

    <p>
      The TPM device enables a QEMU guest to have access to TPM
      functionality.
    </p>
    <p>
      The TPM passthrough device type provides access to the host's TPM
6268
      for one QEMU guest. No other software may be using the TPM device,
6269 6270 6271 6272 6273 6274 6275 6276 6277 6278 6279 6280
      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>
  ...
  &lt;devices&gt;
    &lt;tpm model='tpm-tis'&gt;
      &lt;backend type='passthrough'&gt;
S
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6281
        &lt;device path='/dev/tpm0'/&gt;
6282 6283 6284 6285 6286 6287 6288 6289 6290 6291 6292 6293 6294 6295 6296 6297 6298 6299 6300 6301 6302
      &lt;/backend&gt;
    &lt;/tpm&gt;
  &lt;/devices&gt;
  ...
</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.
        </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>
        <ul>
6303
          <li>'passthrough' &mdash; use the host's TPM device.</li>
6304 6305 6306 6307 6308 6309 6310
        </ul>
      </dd>
      <dt><code>backend type='passthrough'</code></dt>
      <dd>
        <p>
          This backend type requires exclusive access to a TPM device on
          the host.
6311 6312
          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.
6313 6314 6315 6316 6317
          If no file name is specified then /dev/tpm0 is automatically used.
        </p>
      </dd>
    </dl>

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    <h4><a name="elementsNVRAM">NVRAM device</a></h4>
    <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>
  ...
  &lt;devices&gt;
    &lt;nvram&gt;
      &lt;address type='spapr-vio' reg='0x3000'/&gt;
    &lt;/nvram&gt;
  &lt;/devices&gt;
  ...
</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>

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    <h4><a name="elementsPanic">panic device</a></h4>
    <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>
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    <p>
      For pSeries guests, this feature is always enabled since it's
      implemented by the guest firmware, thus libvirt automatically
      adds the <code>panic</code> element to the domain XML.
    </p>
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    <p>
      Example: usage of panic configuration
    </p>
<pre>
  ...
  &lt;devices&gt;
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    &lt;panic model='hyperv'/&gt;
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    &lt;panic model='isa'&gt;
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      &lt;address type='isa' iobase='0x505'/&gt;
    &lt;/panic&gt;
  &lt;/devices&gt;
  ...
</pre>
  <dl>
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    <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>
          <li>'isa' &mdash; for ISA pvpanic device</li>
          <li>'pseries' &mdash; default and valid only for pSeries guests.</li>
          <li>'hyperv' &mdash; for Hyper-V crash CPU feature.
            <span class="since">Since 1.3.0, QEMU and KVM only</span></li>
        </ul>
      </dd>
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    <dt><code>address</code></dt>
    <dd>
      <p>
        address of panic. The default ioport is 0x505. Most users
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        don't need to specify an address, and doing so is forbidden
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        altogether for pseries and hyperv models.
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      </p>
    </dd>
  </dl>

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  <h4><a name="elementsShmem">Shared memory device</a></h4>

    <p>
      A shared memory device allows to share a memory region between
      different virtual machines and the host.
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      <span class="since">Since 1.2.10, QEMU and KVM only</span>
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    </p>

<pre>
  ...
  &lt;devices&gt;
    &lt;shmem name='my_shmem0'&gt;
      &lt;size unit='M'&gt;4&lt;/size&gt;
    &lt;/shmem&gt;
    &lt;shmem name='shmem_server'&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;
  ...
</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>
    <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
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      <code>path</code> attribute specifies the absolute path to the unix socket
      and defaults to <code>/var/lib/libvirt/shmem/$shmem-$name-sock</code>.
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    </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>

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    <h4><a name="elementsMemory">Memory devices</a></h4>

    <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.
      <span class="since">Since 1.2.14</span>
    </p>

    <p>
      Example: usage of the memory devices
    </p>
<pre>
  ...
  &lt;devices&gt;
    &lt;memory model='dimm'&gt;
      &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;
  &lt;/devices&gt;
  ...
</pre>
    <dl>
      <dt><code>model</code></dt>
      <dd>
        <p>
          Currently only the <code>dimm</code> model is supported in order to
          add a virtual DIMM module to the guest.
        </p>
      </dd>

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

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    <h3><a name="seclabel">Security label</a></h3>

    <p>
      The <code>seclabel</code> element allows control over the
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      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
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      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
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      if desired.  <span class="since">'dynamic' since 0.6.1, 'static'
      since 0.6.2, and 'none' since 0.9.10.</span>
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    </p>

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    <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>

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    <p>
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      Valid input XML configurations for the top-level security label
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      are:
    </p>

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

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

  &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;

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

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    <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>

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    <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>
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      <dd>Either <code>static</code>, <code>dynamic</code> or <code>none</code>
        to determine whether libvirt automatically generates a unique security
        label or not.
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      </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>

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    <h3><a name="keywrap">Key Wrap</a></h3>

       <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>

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    <h2><a name="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>