[libvirt] [PATCH v2] qemu: map "virtio" video model to "virt" machtype correctly (arm/aarch64)

[Pavel Hrdina]

On Fri, Sep 16, 2016 at 03:32:59PM +0200, Martin Kletzander wrote:
> On Fri, Sep 16, 2016 at 03:20:16PM +0200, Pavel Hrdina wrote:
> >On Fri, Sep 16, 2016 at 03:06:18PM +0200, Andrea Bolognani wrote:
> >> On Fri, 2016-09-16 at 14:43 +0200, Pavel Hrdina wrote:
> >> > On Fri, Sep 16, 2016 at 09:30:23AM +0200, Laszlo Ersek wrote:
> >> > > Most of QEMU's PCI display device models, such as:
> >> > 
> >> > Pushed, thanks.
> >>
> >> Ouch, you were too fast! ;)
> >>
> >> There is something I wanted to clarify with Laszlo: is
> >> virtio-gpu-pci ever going to be usable on other architectures
> >> such as x86_64? Maybe it already is? Because if that's the
> >> case, we'll want to be able to choose between virtio-vga and
> >> virtio-gpu-pci.
> >>
> >> One solution would be to keep mapping model='virtio' to
> >> virtio-vga and create a new model='virtio-gpu' that maps to
> >> virtio-gpu-pci, then forbid aarch64 mach-virt guests to use
> >> model='virtio'. Or something like that, I'm not married to
> >> the idea, I just think it's something we should definitely
> >> think about before this ends up in a release.
> >
> >I have some patches in my TODO branch that will rewrite the video
> >device code. virtio-gpu-pci is usable also on other architectures
> >but it lacks the VGA compatibility mode.  In libvirt all primary
> >video devices for x86 architecture have VGA mode.  Currently we
> >allow only QXL to be used as secondary video device and now with
> >the virtio-gpu-pci it could be also used as secondary video device.
> >
> >The solution would be simple, there is no need to add a new video
> >model 'virtio-gpu', we will use the existing model 'virtio', but
> >depending on architecture and also whether it's primary or
> >secondary video device we will use appropriate device.
> >We already do this for QXL.
> >
> 
> I'm not sure we're on the same track, so just to confirm I'll ask few
> questions.  We guarantee that on x86_64 primary video devices have
> always VGA compatibility mode?  So virtio-gpu-pci will *never* be able
> to act as a primary video on x64?  If the answers are "yes, yes", then I
> think this patch can stay as it is.  Unless I missed something else.

The answer is yes.  This patch is correct, fixes things on aarch64
and doesn't break anything on x64.

Pavel