Fwd: need help with multimonitor X setup

Jon Smirl jonsmirl at gmail.com
Sun Sep 18 19:48:15 PDT 2005

I forwarded this out to the xorg list. I believe there is a solution
using Matrox cards that will do what you need. I don't use Matrox
cards but there are people on this list that do and can help you
figure out a good setup. There is a version of the Matrox G450 that
supports four heads on a single card.


Hello M. Smirl,

I refer to an article you have published at the following address in
this e-mail


I thought it would be a good idea to e-mail you regarding the subject
in particular

"Making multiuser work"

You seem to be well informed about the actual state development with
the X project, you pointed out limitations and problems regarding
multiuser  and VT assignment (at this time I have only surfaced your
document since I find it a bit technical). I'm in the event photo
business, at this time I have been able to run multiple instance of an
X server that are all independent on 6 screens (5 x PCI RivaTNT2 + 1
AGP RivaTNT2) all this because of this page:

http://cambuca.ldhs.cetuc.puc-rio.br/multiuser/ (you are already aware
of it existance)

The multiple problems that are faced with keyboard aren't an issue for
me, because I don't use any keyboard at all!

At this time our "viewing system" have the following disadvantage:
- It is a bit too big (compared to what could be acheive with dualhead
card on a Mini-ATX form motherboard)
- Won't evolve well in the future because of parts (cost, maintenance,

I'd like to be able to use dual-head card (using Frame-Buffer or other
ways) so that the following objectives could be met (note that I don't
need any keyboard, or video acceleration)
- Having either a system that have the actual system size (but with 12
screens) or having a 6-8 screen system that could fit in a Mini-ATX
tower... (ex: MiniATX, 3PCI-1 AGP = 8 screens total using dual head or
ATX, 5PCI-1AGP = 12 screens total!)
- Would like to use either PCI or PCIe dualhead video card (low cost
is important here)

I have started experiencing 2 heads video card (matrox G400, NVdia
FX5200, ATI Pci card) I have tried to do so with the PCI ID switch in
the XFree86 config file (PCI id 1:0:0 for exemple... etc) without any
success... since each head don't have a unique PCI ID. What happend is
that the fisrt X session always die :(

Miguel Freitas have experianced Matrox G450 Dualhead and has achieve
something with Frame-Buffer.... but will that work with a 6 screens
systems? Plus he was using old version of RedHat and XFree86. Another
person at It's Open (www.itsopen.org) seem to have find a way to use
frame buffer for my needs, but I get a 404 not found when I look for
the documentation

In your article, you point out that: "Note that fbdev works fine when
used by multiple users, it is the VT system that is single user."

At this time, I'm still looking for documentation about making fbdev
work in a multiple user environment.... NO success so far. I'm
thinking about getting more into programming to aheive these thing,
but first I'd like to know if my project is feasible in some way...

Thanks for taking time in reading this.

I'm eager to communicate with you soon.


Claude Ferron
Subito Photo

Jon Smirl
jonsmirl at gmail.com

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