[libvirt] [PATCH v2 3/4] caps: introduce new qemu capability for vgamem_mb device property

[Gerd Hoffmann]

On Fr, 2014-11-14 at 16:15 +0100, Pavel Hrdina wrote:
> On 11/14/2014 04:03 PM, Gerd Hoffmann wrote:
> > On Fr, 2014-11-14 at 14:54 +0100, Pavel Hrdina wrote:
> >> +static struct virQEMUCapsStringFlags
> >> virQEMUCapsObjectPropsCirrusVga[] = {
> >> +    { "vgamem_mb", QEMU_CAPS_CIRRUS_VGA_VGAMEM },
> >> +};
> >
> > Please don't touch vgamem_mb on cirrus.  The only reason we have this
> > property in the first place is live migration compatibility (default vga
> > mem used to be 8MB, but is 16 MB on recent machine types).
> >
> > cheers,
> >    Gerd
> 
> So you are saying that we should not allow setting the 'vgamem_mb' for
> cirrus?

Yes.

>  Is there any reason for that?

We mimic real hardware, and video memory isn't configurable there.  That
we have 8 and 16 mb variants in the first place is not correct, the only
reason we still have that is fixing it breaks live migration.

cheers,
  Gerd