Re: [PULL 12/25] virtio-gpu: move virgl realize + properties

[Gerd Hoffmann]

  Hi,

> Sorry for catching this a bit late, but libvirt is looking for "virgl"
> property when guest XML has 3D acceleration enabled:

Yes, libvirt must be adapted to this.

https://gitlab.com/libvirt/libvirt/-/issues/167

As far I know libvirt checks whenever the virgl property exists to
figure whenever virgl support is available (as you can compile qemu
without virgl support).  So without changes libvirt will simply
think there is no 3d support and configurations without virgl enables
should continue to work fine.

Configurations with virgl enabled will break though, and unfortunaly
there is no easy way to avoid that.

> The commit message suggests that virtio-gpu-gl-device should be used
> instead. Fair enough, so IIUC the cmd line should be changed to:
> 
>   -device virtio-gpu-gl-device,id=video0,max_outputs=1,bus=pci.0,addr=0x2

virtio-gpu-gl-device is the mmio variant, for pci you need
virtio-gpu-gl-pci.  But otherwise yes, this is what libvirt should use
in case it figures qemu supports the virtio-gpu-gl-pci device (again,
when compiling with virgl disabled the device will not be there).

take care,
  Gerd