[Feature request] Multiple X servers on one graphics card?

Prof. Dr. Klaus Kusche klaus.kusche at computerix.info
Mon Aug 1 12:41:18 PDT 2011

On 2011-07-31 22:09, Dave Airlie wrote:
>> There once was a patch to allow one X server per graphics card
>> output:
>> http://www.facebook.com/note.php?note_id=110388492307351
>> http://people.freedesktop.org/~airlied/multiseat/
>> However, this patch never made it to mainline
>> and no longer applies cleanly.
>> Now the question is:
>> * Are there any plans or activities to port these patches
>> to recent kernels? To include these patches or something similar
>> in the official linux kernel any time soon?
> Nothing in my plans, I did a proof of concept to show how someone
> should do things, I'd sort of hoped some of the people who dedicate
> time to fixing multiseat and cared about it would pick things up and
> run with them, it really does need a proper ioctl or configfs
> configuration interface since any static setup will invariable be
> wrong for 50% of people, and any kernel commandline interface will
> invariably be ugly and complex in order to solve the problem.
> I could envisage some sort of configfs where you echo 5>  num_seats
> then echo VGA-1>  seat1, etc.
> Then you could just write some scripts per machine if you don't want
> gdm/consolekit support.

Hmmm, what's about the opposite approach?
To me, it sounds simpler and more logical when the kernel always creates
one device node per output (or maybe dynamically per connected output),
without any need for configuration or device assignment.

If a single X server wants to control several outputs,
libdrm should open the corresponding number of devices in parallel.
We already have both static X configuration and xrandr for configuring
that, and if the devices allow only a single open,
this would also arbitrate outputs between servers
(a server can't open an output which is already taken).


Prof. Dr. Klaus Kusche
Private address: Rainstraße 9/1, 88316 Isny, Germany
+49 7562 6211377 Klaus.Kusche at computerix.info http://www.computerix.info
Office address: NTA Isny gGmbH, Seidenstraße 12-35, 88316 Isny, Germany
+49 7562 9707 36 kusche at nta-isny.de http://www.nta-isny.de

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