DRI and multiple X servers

[Tomas Nykung <tnykung@multi.fi>]

Please allow an long time lurker on this list to ask one question, even
if it might be slightly OT here, ok? :)

I'm still running Debian Woody, but with several backported packages
to get support for my hardware, among others, I've installed Norbert's
backport of X, version 4.3.0.dfsg.1-7.woody.1, to get support for my
(cheap) Radeon 9200 SE graphics card that I've recently bought.
(This works well, at least for me, thanks Norbert if you happens to read
this!)

I of course understand that this is unsupported, my install isn't
anywhere near a standard Debian install and what I want to do isn't
standard either :)



So, here is what I want:
- 3 X servers running at the same time, started from kdm
(for graphical login)

- the first server running at 1024x768, with 16 bits colours, DRI enabled
(for the kids, they mostly play games...)

- the two others running at 1600x1200, with 24 bits colours

So, I edited my /etc/kde2/kdm/Xservers file like this:
:0 local@tty1 /usr/X11R6/bin/X -dpi 75 -nolisten tcp vt7 -depth 16
:1 local@tty2 /usr/X11R6/bin/X :1 -dpi 100 -nolisten tcp vt8 -depth 24
:2 local@tty3 /usr/X11R6/bin/X :2 -dpi 100 -nolisten tcp vt9 -depth 24

and the relevant part of my XF86Config-4 file looks like this:
SubSection "Display"
        Depth           16
        Modes           "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
        Depth		24
	Modes		"1600x1200" "1024x768" "800x600" "640x480"
EndSubSection


This gives me what I wanted:
3 kdm logins, first one on vt7, running 1024x768 16 bits, and the two
others on vt8 and vt9, running 1600x1200 24 bits.

The problem is just with the 3D support...
I understand that it's not possible to get DRI support for more than one
X server at the same time (at least not yet).
I expected the server running on :0 would be the one that would start
first, and thus be the one with DRI support, but that doesn't seem to be
the case... Instead it looks like this is more or less at random(?), and
I cannot figure out how to tell X (or DRI?) which server that should get
access to the DRI.

So, my question is, Is it possible somehow to determine which X server
should have access to the DRI functions?

Of course I could start just the first X server with kdm, and then start
the others with startx -- :1 ... and so on.
Then the first server would always be the one with DRI support as I
want it to be. This would be a good enough solution for me, but it isn't
exactly the most user friendly solution for the other persons using the
same computer.


Any hints from the X and DRI experts on the list?



Tomas