Re: [PATCH v2 1/4] QEMU guest agent support

[Eric Blake <eblake@xxxxxxxxxx>]

On 01/23/2012 07:48 AM, Michal Privoznik wrote:
> There is now a standard QEMU guest agent that can be installed
> and given a virtio serial channel
> 
>     <channel type='unix'>
>       <source mode='bind' path='/var/lib/libvirt/qemu/f16x86_64.agent'/>
>       <target type='virtio' name='org.qemu.guest_agent.0'/>
>     </channel>

You also need to update docs/formatdomain.html.in to include this
specific example.  May I propose that you squash in this:

diff --git i/docs/formatdomain.html.in w/docs/formatdomain.html.in
index de9b480..6667bed 100644
--- i/docs/formatdomain.html.in
+++ w/docs/formatdomain.html.in
@@ -3017,6 +3017,10 @@ qemu-kvm -net nic,model=? /dev/null
     &lt;channel type='pty'&gt;
       &lt;target type='virtio'
name='arbitrary.virtio.serial.port.name'/&gt;
     &lt;/channel&gt;
+    &lt;channel type='unix'&gt;
+      &lt;source mode='bind'
path='/var/lib/libvirt/qemu/f16x86_64.agent'/&gt;
+      &lt;target type='virtio' name='org.qemu.guest_agent.0'/&gt;
+    &lt;/channel&gt;
     &lt;channel type='spicevmc'&gt;
       &lt;target type='virtio' name='com.redhat.spice.0'/&gt;
     &lt;/channel&gt;
@@ -3045,7 +3049,11 @@ qemu-kvm -net nic,model=? /dev/null
         optional element <code>address</code> can tie the channel to a
         particular <code>type='virtio-serial'</code>
         controller, <a href="#elementsAddress">documented above</a>.
-        <span class="since">Since 0.7.7</span></dd>
+        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
+        since 0.9.10</span></dd>

       <dt><code>spicevmc</code></dt>
       <dd>Paravirtualized SPICE channel. The domain must also have a


I think the RNG already covers the addition, though, so we are good
there, and that means that we can get by without any tests/ additions
(we already have tests for virtio <channel> parsing), although it
wouldn't hurt if you wanted to add some tests.


> +struct _qemuAgent {
> +    virMutex lock; /* also used to protect fd */
> +    virCond notify;
> +
> +    int refs;
> +
> +    int fd;
> +    int watch;
> +
> +    bool connectPending;
> +
> +    virDomainObjPtr vm;
> +
> +    qemuAgentCallbacksPtr cb;
> +
> +    /* If there's a command being processed this will be
> +     * non-NULL */
> +    qemuAgentMessagePtr msg;
> +
> +    /* Buffer incoming data ready for Text/QMP monitor
> +     * code to process & find message boundaries */

s,Text/QMP,Agent,


> +    switch (config->type) {
> +    case VIR_DOMAIN_CHR_TYPE_UNIX:
> +        mon->fd = qemuAgentOpenUnix(config->data.nix.path, vm->pid,
> +                                    &mon->connectPending);
> +        break;
> +
> +    case VIR_DOMAIN_CHR_TYPE_PTY:
> +        mon->fd = qemuAgentOpenPty(config->data.file.path);
> +        break;

Do we really want to support <channel type='pty'> for agent interaction,
or just mandate that the guest agent must use <channel type='unix'>?  I
guess we support both for the monitor as well, in case we ever use
qemu-attach to convert a running guest that used a pty monitor into a
libvirt-managed guest.

ACK with above fixes included.

-- 
Eric Blake   eblake@xxxxxxxxxx    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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