[libvirt] [PATCH v2 4/4] qemu-command: introduce new vgamem attribute for video devices

Pavel Hrdina phrdina at redhat.com
Fri Nov 14 18:50:27 UTC 2014


On 11/14/2014 04:25 PM, Gerd Hoffmann wrote:
> On Fr, 2014-11-14 at 16:13 +0100, Pavel Hrdina wrote:
>> On 11/14/2014 04:06 PM, Gerd Hoffmann wrote:
>>> On Fr, 2014-11-14 at 14:54 +0100, Pavel Hrdina wrote:
>>>> +        if (video->vram % 1024) {
>>>> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
>>>> +                           "%s", _("value for 'vram' must be multiple
>>>> of 1024"));
>>>> +            goto error;
>>>> +        }
>>>
>>> pci bar size must be a power of two.  Especially the 9216 default value
>>> libvirt fills in there is *not* valid.  This probably needs some extra
>>> care to handle so existing guest xml files don't blow up things.
>>>
>>> cheers,
>>>     Gerd
>>
>> Default value for QXL is 64MB in libvirt, the 9MB is for other video
>> devices. But we can probably add a special check for QXL device to
>> ensure that ram or vram size is power of 2.
>
> For stdvga and vmware vga it must be a power of two too.
>
> cheers,
>    Gerd
>
>
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We cannot just start enforcing that the vram attribute should be power
of 2. We can ether silently modify the value from user to power of 2 or
let QEMU round the value up to nearest power of 2 value and just add
a note about this to documentation.

Pavel




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