running 2 Xorg servers on a computer

Olivier Demengeon olivier.demengeon at
Tue Nov 14 00:58:27 PST 2006


Tiago Vignatti wrote:
> 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.
It's to use the 3D power of each card, 2 cards compute 3D worlds and the 
graphic card with the keyboard and mouse display it. But it's without 
any SLI things which are not usable, here you can choose what each card 
do and how, so you can have very good performance.
>> 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
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