running 2 Xorg servers on a computer

Tiago Vignatti vignatti at
Mon Nov 13 18:39:23 PST 2006

Olivier Demengeon escreveu:
> Hello
> A few months ago, i configure 2 X servers on a computer, 2 nvidia cards
> 6800 gt and one keyboard and mouse. (nothing to do with SLI, the cards
> was'nt connect together).

Since you're trying to config with one kbd and on mouse, what's the 
reason to setup a dual-head with 2 instances of X servers instead only 
one instance with 2 screens? Just for curiosity.

> Everything run fine, I could use the 2 X servers to do 3D rendering at
> the same times (glxgears at 13000 on X :0.0 and X:1.0). I use to look
> only at one display (:0.0, had only one screen).
> Everything was fine, i keep the config file and after some 3D benchmarks
> tests, i stop to use 2 cards.
> Since a few day now, i try to work again with 2 graphics cards, but i
> lose my xorg config with 2 working cards, so i write a new one.
> My problems is that i doesn't work anymore, i can launch 2 X server, but
> only one seems to run at once, i've to switch to them using crtl-alt-F7
> and crtl-alt-F8, to see a picture, there is no way to look at the two
> together (i use 2 screen and 1 keyboard and 1 mouse) .And only the
> visible one give me good 3D performance.
> I've read the xorg archives and found some threads in 2004 saying that
> there is no way to launch 2 X servers at the same time because each X
> block the PCI bus.
> Do I have dream about my first bench or is it possible from some times ago.
> I use a fedora core 4 with a 2.6.12 kernel, a 6.8.2 xorg and nvidia
> driver. My xorg.conf is attached. I launch the X this way :
>      X :0 -ac -layout L0
>      X :1 -ac -layout L1
> I require just information on the Xorg part (since you have nothing to
> do with nvidia driver), to know if it's possible to launch 2 Xservers on
> a computer with 1 keyboard and 1 mouse, if there is no more problems
> with the sharing of the PCI-express bus. And also some advice for the
> xorg.conf to configure the input, if needed for this case (i've read the
> man a few hours).
> Best regards,
> olivier demengeon

Tiago Vignatti
C3SL - Centro de Computação Científica e Software Livre

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