Re: KVM Fails 3D Acceleration on Debian (failed to validate against schema)

[Peter Krempa <pkrempa@xxxxxxxxxx>]

On Tue, Aug 27, 2024 at 21:36:29 -0000, bo0od--- via Users wrote:
> Full VM xml: 
> 
> ```

[...]

>     <audio id='1' type='spice'/>
>     <video>
>       <model type='virtio' heads='1' primary='yes'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
>       <acceleration accel3d='yes' accel2d='yes'/>
>       <gl enable='yes'/>
>     </video>
>     <watchdog model='itco' action='reset'/>
>     <memballoon model='none'/>
>     <rng model='virtio'>
>       <rate bytes='1024' period='1000'/>
>       <backend model='random'>/dev/random</backend>
>       <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
>     </rng>
>   </devices>
> </domain>
> ```
> 
> But it will always show:
> 
> ```
> error: XML document failed to validate against schema: Unable to validate doc against /usr/share/libvirt/schemas/domain.rng
> Extra element devices in interleave
> Element domain failed to validate content
> ```
> 
> Any idea how to resolve this? 

Error from a XML validator with more reasonable error reporting is:

/tmp/asdfasdf.xml:134:50: error: element "acceleration" not allowed here; expected the element end-tag or element "acpi", "alias" or "driver"
/tmp/asdfasdf.xml:135:25: error: element "gl" not allowed here; expected the element end-tag or element "acpi", "alias" or "driver"

Per https://www.libvirt.org/formatdomain.html#video-devices

The '<acceleration' element is supposed to be a sub-element of 'model':

<devices>
  <video>
    <model type='vga' vram='16384' heads='1'>
      <acceleration accel3d='yes' accel2d='yes'/>
    </model>
    <driver name='qemu'/>
  </video>
</devices>

And '<gl' is supposed to be a child of 'graphics' instead of '<video'.

As you have one at '<graphics' just delete it.

With '<video>' like this it validates properly:

    <video>
      <model type='virtio' heads='1' primary='yes'>
        <acceleration accel3d='yes' accel2d='yes'/>
      </model>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
    </video>

Although I don't know where you got that definition because the qemu
driver doesn't support 'accel2d' altogether:

$ virsh define /tmp/asdfasdf.xml
error: Failed to define domain from /tmp/asdfasdf.xml
error: unsupported configuration: qemu does not support the accel2d setting

In src/qemu/qemu_validate.c in the function qemuValidateDomainDeviceDefVideo()
the check is as follows:

    if (video->accel && video->accel->accel2d == VIR_TRISTATE_BOOL_YES) {
        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                       _("qemu does not support the accel2d setting"));
        return -1;
    }

Thus with no exception.

Thus the final working 'video' is:

    <video>
      <model type='virtio' heads='1' primary='yes'>
        <acceleration accel3d='yes'/>
      </model>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
    </video>

Which is accepted:

$ virsh define /tmp/asdfasdf.xml
Domain 'Whonix-Gateway' defined from /tmp/asdfasdf.xml