Adding QAPI's .o to util-obj-y, common-obj-y and obj-y is spread over
three places: Makefile.objs takes care of target-independent generated
code, Makefile.target of target-dependent generated code, and
qapi/Makefile.objs of (target-independent) hand-written code.

Do everything in qapi/Makefile.objs.
Suggested-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190214152251.2073-8-armbru@redhat.com>

The following patches are going to introduce per-target #ifdef in the
schemas.

The introspection data is statically generated once, and must thus be
built per-target to reflect target-specific configuration.

Drop "do_test_visitor_in_qmp_introspect(&qmp_schema_qlit)" since the
schema is no longer in a common object. It is covered by the per-target
query-qmp-schema test instead.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20190214152251.2073-7-armbru@redhat.com>

Having to include qapi-events.h just for QAPIEvent is suboptimal, but
quite tolerable now.  It'll become problematic when we have events
conditional on the target, because then qapi-events.h won't be usable
from target-independent code anymore.  Avoid that by generating it
into separate files.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190214152251.2073-6-armbru@redhat.com>

Remove a dependency on QEMU. Use the existing logging facilities.
Set SLIRP_DEBUG=tftp to get tftp log.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: NSamuel Thibault <samuel.thibault@ens-lyon.org>

This will allow to have cflags for the whole slirp.mo -objs.
It makes it possible to build tests that links only with
slirp-obj-y (and not the whole common-obj).

It is also a step towards building slirp as a shared library, although
this requires a bit more thoughts to build with
net/slirp.o (CONFIG_SLIRP would need to be 'm') and other build issues.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: NSamuel Thibault <samuel.thibault@ens-lyon.org>

Useful when debugging pxeboot, to see what the guest tries to do.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Reviewed-by: NLiam Merwick <liam.merwick@oracle.com>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: NSamuel Thibault <samuel.thibault@ens-lyon.org>

This adds a model of the nRF51 GPIO peripheral.

Reference Manual: http://infocenter.nordicsemi.com/pdf/nRF51_RM_v3.0.pdf

The nRF51 series microcontrollers support up to 32 GPIO pins in various configurations.
The pins can be used as input pins with pull-ups or pull-down.
Furthermore, three different output driver modes per level are
available (disconnected, standard, high-current).

The GPIO-Peripheral has a mechanism for detecting level changes which is
not featured in this model.
Signed-off-by: NSteffen Görtz <contrib@steffen-goertz.de>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 20190103091119.9367-6-stefanha@redhat.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

pvrdma requires that the same GID attached to it will be attached to the
backend device in the host.

A new QMP messages is defined so pvrdma device can broadcast any change
made to its GID table. This event is captured by libvirt which in  turn
will update the GID table in the backend device.
Signed-off-by: NYuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: NMarcel Apfelbaum <marcel.apfelbaum@gmail.com>
Acked-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMarcel Apfelbaum <marcel.apfelbaum@gmail.com>

RDMA MAD kernel module (ibcm) disallow more than one MAD-agent for a
given MAD class.
This does not go hand-by-hand with qemu pvrdma device's requirements
where each VM is MAD agent.
Fix it by adding implementation of RDMA MAD multiplexer service which on
one hand register as a sole MAD agent with the kernel module and on the
other hand gives service to more than one VM.

Design Overview:
Reviewed-by: NShamir Rabinovitch <shamir.rabinovitch@oracle.com>
----------------
A server process is registered to UMAD framework (for this to work the
rdma_cm kernel module needs to be unloaded) and creates a unix socket to
listen to incoming request from clients.
A client process (such as QEMU) connects to this unix socket and
registers with its own GID.

TX:
----
When client needs to send rdma_cm MAD message it construct it the same
way as without this multiplexer, i.e. creates a umad packet but this
time it writes its content to the socket instead of calling umad_send().
The server, upon receiving such a message fetch local_comm_id from it so
a context for this session can be maintain and relay the message to UMAD
layer by calling umad_send().

RX:
----
The server creates a worker thread to process incoming rdma_cm MAD
messages. When an incoming message arrived (umad_recv()) the server,
depending on the message type (attr_id) looks for target client by
either searching in gid->fd table or in local_comm_id->fd table. With
the extracted fd the server relays to incoming message to the client.
Signed-off-by: NYuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: NShamir Rabinovitch <shamir.rabinovitch@oracle.com>
Signed-off-by: NMarcel Apfelbaum <marcel.apfelbaum@gmail.com>

Adding a new qapi module had some rather tedious repetition to
wire it into Makefile, Makefile.objs, and .gitignore (for example,
see commit bf42508f and its followup b61acdec). For make, add some
indirection by taking advantage of GNU Make string processing to
expand a list of module names into all the required artifacts, so
that future additions of a new module need only touch the list of
module names.  And for gitignore, use globs to cover all generated
file names.

The list has to live in Makefile.objs, due to the way that
our unnest-vars macro slirps in that file without remembering
any definition of $(QAPI_MODULES) from Makefile.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Tested-by: NYuval Shaia <yuval.shaia@oracle.com>
Message-Id: <20181116200016.2080785-1-eblake@redhat.com>
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>

elf2dmp is a converter from ELF dump (produced by 'dump-guest-memory') to
Windows MEMORY.DMP format (also know as 'Complete Memory Dump') which can be
opened in WinDbg.

This tool can help if VMCoreInfo device/driver is absent in Windows VM and
'dump-guest-memory -w' is not available but dump can be created in ELF format.

The tool works as follows:
1. Determine the system paging root looking at GS_BASE or KERNEL_GS_BASE
to locate the PRCB structure and finds the kernel CR3 nearby if QEMU CPU
state CR3 is not suitable.
2. Find an address within the kernel image by dereferencing the first
IDT entry and scans virtual memory upwards until the start of the
kernel.
3. Download a PDB matching the kernel from the Microsoft symbol store,
and figure out the layout of certain relevant structures necessary for
the dump.
4. Populate the corresponding structures in the memory image and create
the appropriate dump header.
Signed-off-by: NViktor Prutyanov <viktor.prutyanov@virtuozzo.com>
Message-Id: <1535546488-30208-3-git-send-email-viktor.prutyanov@virtuozzo.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The Arm Cortex-M System Design Kit includes a simple watchdog module
based on a 32-bit down-counter. Implement this.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Signed-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180606191801.6331-1-f4bug@amsat.org
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Having these entries sorted helps to add new ones.
Signed-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180528054055.21153-1-f4bug@amsat.org
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

This adds QMP commands that control the transition between states of the
job lifecycle.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This adds a separate schema file for all job-related definitions that
aren't tied to the block layer.

For a start, move the enums JobType, JobStatus and JobVerb.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

This is the first step towards creating an infrastructure for generic
background jobs that aren't tied to a block device. For now, Job only
stores its ID and JobDriver, the rest stays in BlockJob.

The following patches will move over more parts of BlockJob to Job if
they are meaningful outside the context of a block job.

BlockJob.driver is now redundant, but this patch leaves it around to
avoid unnecessary churn. The next patches will get rid of almost all of
its uses anyway so that it can be removed later with much less churn.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>

Add audio/ to common-obj-m variable.

Also run both audio and ui variables through unnest-vars.
This avoids sdl.mo (exists in both audio/ and ui/) name clashes.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Message-id: 20180306074053.22856-4-kraxel@redhat.com

Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>

If a requested user interface is not available, try loading it as
module, simliar to block layer modules.  Needed to keep things working
when followup patches start to build user interfaces as modules.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Message-id: 20180301100547.18962-8-kraxel@redhat.com

Move qapi-schema.json to qapi/, so it's next to its modules, and all
files get generated to qapi/, not just the ones generated for modules.

Consistently name the generated files qapi-MODULE.EXT:
qmp-commands.[ch] become qapi-commands.[ch], qapi-event.[ch] become
qapi-events.[ch], and qmp-introspect.[ch] become qapi-introspect.[ch].
This gets rid of the temporary hacks in scripts/qapi/commands.py,
scripts/qapi/events.py, and scripts/qapi/common.py.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20180211093607.27351-28-armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
[eblake: Fix trailing dot in tpm.c, undo temporary hack for OSX toolchain]
Signed-off-by: NEric Blake <eblake@redhat.com>

The previous commit improved compile time by including less of the
generated QAPI headers.  This is impossible for stuff defined directly
in qapi-schema.json, because that ends up in headers that that pull in
everything.

Move everything but include directives from qapi-schema.json to new
sub-module qapi/misc.json, then include just the "misc" shard where
possible.

It's possible everywhere, except:

* monitor.c needs qmp-command.h to get qmp_init_marshal()

* monitor.c, ui/vnc.c and the generated qapi-event-FOO.c need
  qapi-event.h to get enum QAPIEvent

Perhaps we'll get rid of those some other day.

Adding a type to qapi/migration.json now recompiles some 120 instead
of 2300 out of 5100 objects.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20180211093607.27351-25-armbru@redhat.com>
[eblake: rebase to master]
Signed-off-by: NEric Blake <eblake@redhat.com>

Our qapi-schema.json is composed of modules connected by include
directives, but the generated code is monolithic all the same: one
qapi-types.h with all the types, one qapi-visit.h with all the
visitors, and so forth.  These monolithic headers get included all
over the place.  In my "build everything" tree, adding a QAPI type
recompiles about 4800 out of 5100 objects.

We wouldn't write such monolithic headers by hand.  It stands to
reason that we shouldn't generate them, either.

Split up generated qapi-types.h to mirror the schema's modular
structure: one header per module.  Name the main module's header
qapi-types.h, and sub-module D/B.json's header D/qapi-types-B.h.

Mirror the schema's includes in the headers, so that qapi-types.h gets
you everything exactly as before.  If you need less, you can include
one or more of the sub-module headers.  To be exploited shortly.

Split up qapi-types.c, qapi-visit.h, qapi-visit.c, qmp-commands.h,
qmp-commands.c, qapi-event.h, qapi-event.c the same way.
qmp-introspect.h, qmp-introspect.c and qapi.texi remain monolithic.

The split of qmp-commands.c duplicates static helper function
qmp_marshal_output_str() in qapi-commands-char.c and
qapi-commands-misc.c.  This happens when commands returning the same
type occur in multiple modules.  Not worth avoiding.

Since I'm going to rename qapi-event.[ch] to qapi-events.[ch], and
qmp-commands.[ch] to qapi-commands.[ch], name the shards that way
already, to reduce churn.  This requires temporary hacks in
commands.py and events.py.  Similarly, c_name() must temporarily
be taught to munge '/' in common.py.  They'll go away with the rename.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20180211093607.27351-23-armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
[eblake: declare a dummy variable in each .c file, to shut up OSX
toolchain warnings about empty .o files, including hacking c_name()]
Signed-off-by: NEric Blake <eblake@redhat.com>

Linking code from multiple separate QAPI schemata into the same
program is possible, but involves some weirdness around built-in
types:

* We generate code for built-in types into .c only with option
  --builtins.  The user is responsible for generating code for exactly
  one QAPI schema per program with --builtins.

* We generate code for built-in types into .h regardless of
  --builtins, but guarded by #ifndef QAPI_VISIT_BUILTIN.  Because all
  copies of this code are exactly the same, including any combination
  of these headers works.

Replace this contraption by something more conventional: generate code
for built-in types into their very own files: qapi-builtin-types.c,
qapi-builtin-visit.c, qapi-builtin-types.h, qapi-builtin-visit.h, but
only with --builtins.  Obey --output-dir, but ignore --prefix for
them.

Make qapi-types.h include qapi-builtin-types.h.  With multiple
schemata you now have multiple qapi-types.[ch], but only one
qapi-builtin-types.[ch].  Same for qapi-visit.[ch] and
qapi-builtin-visit.[ch].

Bonus: if all you need is built-in stuff, you can include a much
smaller header.  To be exploited shortly.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20180211093607.27351-21-armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
[eblake: fix octal constant for python 3]
Signed-off-by: NEric Blake <eblake@redhat.com>

All generated .c are named like their .h, except for qmp-marshal.c and
qmp-commands.h.  To add to the confusion, tests-qmp-commands.c falsely
matches generated test-qmp-commands.h.

Get rid of this unnecessary complication.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20180211093607.27351-19-armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: NEric Blake <eblake@redhat.com>

PVRDMA is the QEMU implementation of VMware's paravirtualized RDMA device.
It works with its Linux Kernel driver AS IS, no need for any special
guest modifications.

While it complies with the VMware device, it can also communicate with
bare metal RDMA-enabled machines and does not require an RDMA HCA in the
host, it can work with Soft-RoCE (rxe).

It does not require the whole guest RAM to be pinned allowing memory
over-commit and, even if not implemented yet, migration support will be
possible with some HW assistance.

Implementation is divided into 2 components, rdma general and pvRDMA
specific functions and structures.

The second PVRDMA sub-module - interaction with PCI layer.
- Device configuration and setup (MSIX, BARs etc).
- Setup of DSR (Device Shared Resources)
- Setup of device ring.
- Device management.
Reviewed-by: NDotan Barak <dotanb@mellanox.com>
Reviewed-by: NZhu Yanjun <yanjun.zhu@oracle.com>
Signed-off-by: NYuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: NMarcel Apfelbaum <marcel@redhat.com>

This layer is composed of two sub-modules, backend and resource manager.
Backend sub-module is responsible for all the interaction with IB layers
such as ibverbs and umad (external libraries).
Resource manager is a collection of functions and structures to manage
RDMA resources such as QPs, CQs and MRs.
Reviewed-by: NDotan Barak <dotanb@mellanox.com>
Reviewed-by: NZhu Yanjun <yanjun.zhu@oracle.com>
Signed-off-by: NYuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: NMarcel Apfelbaum <marcel@redhat.com>

Signed-off-by: NMark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

Now that we have the prerequisites in target/hppa/,
implement the hardware for a PA7100LC.

This also enables build for hppa-softmmu.
Signed-off-by: NHelge Deller <deller@gmx.de>
[rth: Since it is all new code, squashed all branch development
withing hw/hppa/ to a single patch.]
Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>

Signed-off-by: NMark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
CC: Michael S. Tsirkin <mst@redhat.com>
CC: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: NArtyom Tarasenko <atar4qemu@gmail.com>
[for addition of trace-events to hw/pci-host]
Acked-by: NMichael S. Tsirkin <mst@redhat.com>

This commit introduces a vhost-user-blk backend device, it uses UNIX
domain socket to communicate with QEMU. The vhost-user-blk sample
application should be used with QEMU vhost-user-blk-pci device.

To use it, complie with:
make vhost-user-blk

and start like this:
vhost-user-blk -b /dev/sdb -s /path/vhost.socket
Signed-off-by: NChangpeng Liu <changpeng.liu@intel.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

This is in preparation for switching code in hw/sparc64 from DPRINTF over to
trace events.
Signed-off-by: NMark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: NArtyom Tarasenko <atar4qemu@gmail.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>

Commit c37cacab moved tpm_cleanup() in the main loop exit, however this
function is not available when compiling with --disable-tpm.

Provides necessary stubs to keep code clean of #ifdef'fery.
Reported-by: NBALATON Zoltan <balaton@eik.bme.hu>
Message-Id: <20171023102903.256AF7456A0@zero.eik.bme.hu>
Signed-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: NRichard W.M. Jones <rjones@redhat.com>
Reviewed-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>

Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>

It is a common requirement for virtual machine to send persistent
reservations, but this currently requires either running QEMU with
CAP_SYS_RAWIO, or using out-of-tree patches that let an unprivileged
QEMU bypass Linux's filter on SG_IO commands.

As an alternative mechanism, the next patches will introduce a
privileged helper to run persistent reservation commands without
expanding QEMU's attack surface unnecessarily.

The helper is invoked through a "pr-manager" QOM object, to which
file-posix.c passes SG_IO requests for PERSISTENT RESERVE OUT and
PERSISTENT RESERVE IN commands.  For example:

  $ qemu-system-x86_64
      -device virtio-scsi \
      -object pr-manager-helper,id=helper0,path=/var/run/qemu-pr-helper.sock
      -drive if=none,id=hd,driver=raw,file.filename=/dev/sdb,file.pr-manager=helper0
      -device scsi-block,drive=hd

or:

  $ qemu-system-x86_64
      -device virtio-scsi \
      -object pr-manager-helper,id=helper0,path=/var/run/qemu-pr-helper.sock
      -blockdev node-name=hd,driver=raw,file.driver=host_device,file.filename=/dev/sdb,file.pr-manager=helper0
      -device scsi-block,drive=hd

Multiple pr-manager implementations are conceivable and possible, though
only one is implemented right now.  For example, a pr-manager could:

- talk directly to the multipath daemon from a privileged QEMU
  (i.e. QEMU links to libmpathpersist); this makes reservation work
  properly with multipath, but still requires CAP_SYS_RAWIO

- use the Linux IOC_PR_* ioctls (they require CAP_SYS_ADMIN though)

- more interestingly, implement reservations directly in QEMU
  through file system locks or a shared database (e.g. sqlite)
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

util/scsi.c includes some SCSI code that is shared by block/iscsi.c and
hw/scsi, but the introduction of the persistent reservation helper
will add many more instances of this.  There is also include/block/scsi.h,
which actually is not part of the core block layer.

The persistent reservation manager will also need a home.  A scsi/
directory provides one for both the aforementioned shared code and
the PR manager code.
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Remove the DEBUG_IDE preprocessor definition with something more
appropriately flexible, using the trace-events subsystem.

This will be less prone to bitrot and will more effectively allow
us to target just the functions we care about.
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 20170901001502.29915-2-jsnow@redhat.com
Signed-off-by: NJohn Snow <jsnow@redhat.com>

Like many other libraries, libseccomp cflags and libs should only apply
to the building of necessary objects. Do so in the usual way with the
help of per object variables.
Signed-off-by: NFam Zheng <famz@redhat.com>

Don't try to build the ivshmem-server and ivshmem-client tools unless
CONFIG_IVSHMEM is set.

This fixes in passing a build bug on NetBSD, which fails to build the
ivshmem tools because they use shm_open() and on NetBSD that requires
linking against -lrt.
Signed-off-by: NKamil Rytarowski <n54@gmx.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1500021225-4118-4-git-send-email-peter.maydell@linaro.org
[PMM: moved some code into earlier patches; minor bugfixes;
 added commit message]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

The content of the backends/trace-events file was entirely
removed in

  commit 6b10e573
  Author: Marc-André Lureau <marcandre.lureau@redhat.com>
  Date:   Mon May 29 12:39:42 2017 +0400

    char: move char devices to chardev/

Leaving the empty file around, causes tracetool to generate
an empty .dtrace file which makes the dtrace compiler throw
a syntax error.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20170629162046.4135-1-berrange@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>