[Engine-devel] [Spice-devel] SPICE related features
Alon Levy
alevy at redhat.com
Wed Feb 15 12:51:47 UTC 2012
On Wed, Feb 15, 2012 at 06:25:37AM -0500, Oved Ourfalli wrote:
>
>
> ----- Original Message -----
> > From: "Dor Laor" <dlaor at redhat.com>
> > To: spice-devel at lists.freedesktop.org, engine-devel at ovirt.org
> > Cc: "David Jaša" <djasa at redhat.com>, "Oved Ourfalli" <ovedo at redhat.com>, "Hans de Goede" <hdegoede at redhat.com>
> > Sent: Wednesday, February 15, 2012 12:52:46 PM
> > Subject: Re: [Engine-devel] [Spice-devel] SPICE related features
> >
> > On 02/09/2012 02:50 PM, David Jaša wrote:
> > > Itamar Heim píše v Čt 09. 02. 2012 v 11:07 +0200:
> > >> On 02/09/2012 11:05 AM, Hans de Goede wrote:
> > >>> Hi,
> > >>>
> > >>> On 02/09/2012 09:33 AM, Itamar Heim wrote:
> > >>>> On 02/09/2012 10:31 AM, Hans de Goede wrote:
> > >>>
> > >>> <snip>
> > >>>
> > >>>>>> 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?
> > >>>
> > >>> I see this as something which gets decided at vm creation time,
> > >>> and then
> > >>> stored in the vm config. So if the vm gets created with a guest
> > >>> OS which
> > >>> does not support multiple monitors per qxl device, or when the
> > >>> cluster does
> > >>> not support it, it uses the old setup with 1 card / monitor. Even
> > >>> if the
> > >>> guest OS or the cluster gets upgraded later.
> > >>
> > >> so instead of letting user change this, we'd force this at vm
> > >> creation
> > >> time? I'm not sure this is "friendlier".
> > >
> > > I think that some history-watching logic& one UI bit could be the
> > > way
> > > to go. The UI bit would be yet another select button that would let
> > > user
> > > choose what graphic layout ("all monitors on single graphic card",
> > > "one
> > > graphic card per monitor (legacy)"). The logic would be like this:
> > > * pre-existing guest that now supports new layout in 3.1
> > > cluster
> > > * The guest uses 1 monitor, is swithed to 2+ -->
> > > new
> > > * The guest uses 2+ monitor layout --> old, big fat
> > > warning when changing to the new that user should
> > > wipe
> > > xinerama configuration in the guest
> > > * pre-existing guest in old or mixed cluster:
> > > * guest uses 2+ monitors --> old
> > > * guest is newly configured for 2+ monitors -->
> > > show
> > > warning that user either has co configure xinerama
> > > or
> > > use newer cluster --> old
> > > * new guest in new cluster:
> > > * --> new
> > > * if user switches to old, show warning
> > > * old guest in any type of cluster
> > > * --> old
> > >
> > > This kind of behavior should provide sensible defaults, all valid
> > > choices in all possible scenarios and it should not interfere too
> > > much
> > > when admin chooses to do anything.
> >
> > In short, the same rule of the thumb applies to all of our virtual
> > hardware:
> > - new vm creation should use the greatest and latest virtual
> > hardware
> > version (if the current cluster allows it)
> > - For existing VMs we should preserve their current virtual
> > hardware
> > set (-M flag in qemu machine type vocabulary, cluster
> > terminology
> > for ovirt).
> > - Changing the virtual hardware by either changing existing
> > devices,
> > adding devices, changing pci slots, or changing the virtual
> > hardware revision should done only by user consent.
> > The later may have the exception of smart offline v2v tool.
> >
> > Dor
> >
>
> I agree.
> What I don't understand (not a question for you Dor, but more for the SPICE guys), though, is the requirement to support Xinerama configuration on the guest.
> Today the ovirt-engine doesn't support using more than one monitor on Linux guests.
Why? With Xinerama support we have a solution for this. That's the
reason for asking for more the one monitor support for linux guests, no?
> If someone did something with is not the standard, somewhere behind the scenes, the engine cannot be aware of that, thus it cannot take it into consideration.
> Moreover, don't change the device layout when we add support, as the guest had one display device with one head, and it will remain that way, unless he chooses to work with multiple monitors through the engine management system.
>
> > >
> > > David
> > >
> > >> ______________________________________
> > >> _________
> > >> Engine-devel mailing list
> > >> Engine-devel at ovirt.org
> > >> http://lists.ovirt.org/mailman/listinfo/engine-devel
> > >
> >
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> > Engine-devel at ovirt.org
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> >
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