Bug 787569

Summary:	RFE: add support for multiple monitors on QXL device
Product:	Red Hat Enterprise Linux 6	Reporter:	Oved Ourfali <oourfali>
Component:	libvirt	Assignee:	Martin Kletzander <mkletzan>
Status:	CLOSED NOTABUG	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	6.3	CC:	acathrow, alevy, berrange, dallan, danken, dyuan, iheim, mshao, mzhan, oourfali, rwu, zpeng
Target Milestone:	rc	Keywords:	FutureFeature
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Enhancement
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2012-08-08 17:47:46 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	770842, 842298, 842305, 842310, 842411
Bug Blocks:

Description Oved Ourfali 2012-02-06 07:40:08 UTC

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 Berrangé 2012-02-06 10:23:59 UTC

> 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 Berrangé 2012-07-23 12:25:54 UTC

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 13:16:09 UTC

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 14:11:57 UTC

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 19:02:15 UTC

(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 17:47:46 UTC

(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 18:56:20 UTC

Sorry for the late reply.
According to the latest comments it looks like nothing is indeed needed.

Thank you,
Oved