Bug 787569 - RFE: add support for multiple monitors on QXL device
RFE: add support for multiple monitors on QXL device
Status: CLOSED NOTABUG
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: libvirt (Show other bugs)
6.3
Unspecified Unspecified
unspecified Severity unspecified
: rc
: ---
Assigned To: Martin Kletzander
Virtualization Bugs
: FutureFeature
Depends On: 770842 842298 842305 842310 842411
Blocks:
  Show dependency treegraph
 
Reported: 2012-02-06 02:40 EST by Oved Ourfali
Modified: 2013-01-25 07:33 EST (History)
12 users (show)

See Also:
Fixed In Version:
Doc Type: Enhancement
Doc Text:
Story Points: ---
Clone Of:
Environment:
Last Closed: 2012-08-08 13:47:46 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
CRM:
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---


Attachments (Terms of Use)

  None (edit)
Description Oved Ourfali 2012-02-06 02:40:08 EST
Description of problem:

To get n monitors emulated in the guest currently required n pci qxl devices.
This has several problems:
 needless waste of memory.
 hard to support for linux guests (Xinerama required, Xrandr doesn't allow
different cards)

See planned qemu support in bug #770842.

Suggested solution:
Perhaps using the "heads" property to specify the number of monitors?
Comment 2 Daniel Berrange 2012-02-06 05:23:59 EST
> Perhaps using the "heads" property to specify the number of monitors?

Yes, that is the correct way to model video cards which have multiple outputs.
Comment 3 Daniel Berrange 2012-07-23 08:25:54 EDT
Talking to Alon on #spice last week, I learnt that there is not actually any host visible configuration required in order to support multiple monitor mode with QXL. It is all negotiated directly between the SPICE client and the guest QXL driver. So I'm not sure there's any work to be done in libvirtd itself afterall.
Comment 4 Martin Kletzander 2012-07-23 09:16:09 EDT
Sounds good. But maybe there is a initial configuration that might be exposed? I mean the 'heads' parameter should mean how many monitors will be 'connected' at start (something like the proposed -global qxl-vga.num_displays=2 or similar).

I think that if this is supported than we should modify the behavior in this way as well.
Comment 5 Alon Levy 2012-07-23 10:11:57 EDT
Martin,

 The way this was designed there is no need to involve the host in the number of monitors - and conversely there is no way for the host to request a limitation to the number of monitors. Practically the number of monitors will be limited by either the guest actions directly (xrandr / gnome-control-center) or by client triggered (initial MonitorsConfig sent when client connects).

 So there is no need or meaning to have a heads parameter.

 If you would say what you are trying to accomplish it would be possible to discuss a fix for it.

Alon
Comment 6 Martin Kletzander 2012-07-23 15:02:15 EDT
(In reply to comment #5)
I was just trying to clarify if anything is needed and you basically answered my question, so from my point of view this could be closed as NOTABUG.

What is your opinion, Oved?
Comment 7 Dave Allan 2012-08-08 13:47:46 EDT
(In reply to comment #6)
> I was just trying to clarify if anything is needed and you basically
> answered my question, so from my point of view this could be closed as
> NOTABUG.

That seems correct to me, so I'm closing as NOTABUG, but if I'm wrong about that of course reopen.
Comment 8 Oved Ourfali 2012-08-08 14:56:20 EDT
Sorry for the late reply.
According to the latest comments it looks like nothing is indeed needed.

Thank you,
Oved

Note You need to log in before you can comment on or make changes to this bug.