[Spice-devel] [Engine-devel] SPICE related features

[Itamar Heim]

On 02/09/2012 10:31 AM, Hans de Goede wrote:
> Hi,
>
> On 02/09/2012 08:55 AM, Itamar Heim wrote:
>> On 02/08/2012 04:36 PM, Hans de Goede wrote:
>>> Hi all,
>>>
>>> Dor, thanks for the forward.
>>>
>>> On 02/08/2012 12:49 PM, Dor Laor wrote:
>>>> On 02/08/2012 01:43 PM, Oved Ourfalli wrote:
>>>>> Hello all,
>>>>>
>>>>> The following feature page describes the engine adjustments needed
>>>>> for new SPICE features.
>>>>>
>>>>> http://www.ovirt.org/wiki/Features/SPICERelatedFeatures
>>>
>>> Al in all this looks good, some remarks:
>>>
>>> * WRT multi monitor support for RHEL, the latest RHEL
>>> xorg-x11-drv-qxl and
>>> spice-vdagent packages do support multi monitor support using multiple
>>> cards in Xinerama mode. We are waiting for a RHEL-6 z-stream update to
>>> fix an x11-xorg-server-Xorg bug which atm makes the mouse unusable in
>>> this
>>> mode wants this lands, multi-monitor support this way should be
>>> available
>>> for RHEL-6.2 (and later) guests. The same holds true for Fedora guests,
>>> although I don't expect the necessary Xorg changes to be available for
>>> versions older then Fedora 17. The driving multiple monitors from a
>>> single
>>> qxl device support OTOH is still a long time away, likely 6 months or
>>> so.
>>
>> so this means we need to ask the user for linux guests if they want
>> single head or multiple heads when they choose multi monitor?
>
> We could ask the user, but I don't think that that is a good idea.
>
>> this will cause their (single) head to spin...
>
> With which you seem to agree :)
>
>> any better UX we can suggest users?
>
> Yes, no UI at all, the current solution using multiple single monitor
> pci cards means using Xinerama, which disables Xrandr, and thus allows
> no dynamic adjustment of the monitor settings of the guest, instead
> an xorg.conf file must be written (the linux agent can generate one
> based on the current client monitor info) and Xorg needs to be restarted.
>
> This is the result of the multiple pci cards which each 1 monitor model
> we've been using for windows guests being a poor match for Linux guests.
>
> So we are working on adding support to drive multiple monitors from a
> single qxl pci device. This requires changes on both the host and
> guest side, but if both sides support it this configuration is much
> better, so IMHO ovirt should just automatically enable it
> if both the host (the cluster) and the guest support it.
>
> On the guest side, this is the current status:
>
> RHEL <= 6.1 no multi monitor support
> RHEL 6.2(*) - 6.? multi monitor support using Xinerama (so 1
> monitor/card, multiple cards)
> RHEL >= 6.? multi monitor support using a single card with multiple outputs
>
> Just like when exactly the new multi mon support will be available
> for guests, it is a similar question mark for when it will be available for
> the host.

this is the ovirt mailing list, so upstream versions are more relevant here.
in any case, I have the same issue with backward compatibilty.
say you fix this in fedora 17.
user started a guest VM when host was fedora 16.
admin upgraded host and changed cluster level to utilize new features.
suddenly on next boot guest will move from 4 heads to single head? I'm 
guessing it will break user configuration.
i.e., user should be able to choose to move to utilize the new mode?