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

Prof. Dr. Klaus Kusche klaus.kusche at computerix.info
Sat Jul 30 11:48:09 PDT 2011

Mainboards with 4 or even up to 7 PCIe x8 or x16 slots are available
today, and graphics cards with 3 to 5 outputs are also common.

Such a combination would make a very attractive classroom server
for up to 25 pupils/students, cheaper than any other solution,
much easier to administrate than a network of single-seat PC's,
and much faster w.r.t. graphics than a server with thin clients.
We would be highly interested in such a solution
(I'm a professor for computer science at a technical high school
and university of applied sciences),
and I'm currently investigating the possibilities for that.

Unfortunately, currently only Xephyr can be used for that,
which doesn't support hardware acceleration
(and hence makes e.g. Gnome 3 unhappy and video playback slow).

There once was a patch to allow one X server per graphics card

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?

* How much work (and how complex/difficult) would it be to port
these patches to the current linux kernel?
Could that be assigned to a student?

* Is there anyone who is experienced in that area of the kernel
and would implement that (and push it to the official kernel),
perhaps with some financial support (how much would that cost)?

I'd just need the base functionality:

* Static configuration of render devices (via kernel boot parameter?)
or even just one hardcoded device / X server per graphics card output,
no need to assign devices to output combinations dynamically.

(perhaps being able to assign symbolic links to the device nodes
based on card and output number with udev would be nice)

* No need to have any gdm / consolekit support for that.

* ATI radeon only.

The competition is offering exactly that to us:
The beast is called "Microsoft MultiPoint Server". It is a product
created especially for the educational market (and seems to be quite
successful there), but also offered for small offices.

Technically, it is a multi-user Windows server supporting up to 20
local users, each user being assigned one port of a local graphics card
(or one USB graphics card) and a USB keyboard and mouse.

It explicitely provides one user per graphics output port,
not just per card, exactly what I would like to have for linux.

So I'd need some linux equivalent to compete with that w.r.t.
number of seats per PC/server to get a linux classroom installed
at our school instead of Windows...

Many thanks in advance for your help!

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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