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Old 04-16-06, 01:38 AM   #1
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Default Multiseat using a single card?

is it possible to use xorg's multi-seat support on a single nvidia card?

i have a Geforce 6800 GT with a 2 DVIs and 1 TV-Out

im trying to set up multiseat using 1 with a dvi and 1 with a tv-out

both of them work fine seperately
and both of them work fine using whatever it is where you use 2 x screens in a single instance of X?
but what i want to do is true multseat where you have a seperate mouse keyboard and video for each

it seems like it might work but i havent actually gotten them to both come up at the same time on the same vt or whatever..

is it possible? has anyone else done it?
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Old 04-16-06, 05:52 AM   #2
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Default Re: Multiseat using a single card?

In case of nvidia hardware this is not possible as both screens need to be in the same Xsession and there's no way to assign a different keyboard to each X screen. If you could use the card as two separate videocards as was possible using matrox and ati cards (a card appeared as two videocards in the system) then it would have been possible.
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Old 04-17-06, 10:50 AM   #3
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Default Re: Multiseat using a single card?

what exactly is the problem? is it a hardware thing or software thing?

could drivers fix it?
or could xorg patches fix it?

you can use each display on its own vt, both running at the same time, but just not both visible at the same time

like i could have either display independantly OR run CRT on vt7 and TV on vt8 (at the same time) but only one vt is visible at once..

it seems like if it can do that much then it should be possible to .. display them both at once

but i havent had any luck with it

it seems like im sooo close that it should be possible
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Old 04-21-06, 08:15 AM   #4
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Default Re: Multiseat using a single card?

You need to have the evdev component of X installed or else this doesn't work, but then you can specify which keyboard you want to use:

Section "InputDevice"
Identifier "601LeftBenchKeyboard"
Driver "evdev"
Option "Device" "/dev/input/event0"
Option "AutoRepeat" "500 50"

Then run two X servers on the same vt by editing gdm.conf:

0=Standard -layout X0 vt7
1=Standard -layout X1 vt7

Where you have two serverlayouts defined for the two setups.


No I have to concede I can see why this could cause problems with the nvidia way of doing things... Throw a PCI graphics card into your system and you've got it solved.
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Old 05-08-06, 11:08 AM   #5
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Default Re: Multiseat using a single card?

I'll probably poke about over the summer to see if I can find a legacy PCI card, but it would be muchos cool if it Just Worked.

Does anyone think it *could* be fixed with a new driver?

I get the feeling that once xorg 7.0 becomes popular with the hobbyists (probably as soon as Gentoo keywords it as stable on x86), there will be MANY people trying this with their Twinview cards

If anyone manages to get this working, please post.
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Old 05-08-06, 11:40 AM   #6
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Default Re: Multiseat using a single card?

The desire for a multiseat single card solution has been raised a couple
of times over the past few years. Except for multi-GPU cards, I'm not
aware of an OOTB solution to get things done the way you'd like it.

However, i think that it is basically possible to create a multiseat
environment using a single GPU card without the need for a new driver:

1. Setup the nvidia card with multiple screens and SW cursor
2. Implement a second mouse-pointer in Xorg
3. Limit each mouse-pointer to one of the screens.
4. Teach Xorg to redirect multiple input events to the appropriate screen

Step 1 is easy (see NV README), but the rest is probably at least
one month of implementation effort.

I guess that it would technically be possible to have two
X-Servers running in parallel, displaying on different outputs,
but this would require changes in the NV display driver (i.e. GPU
access arbitration)

I think it is by far simpler to purchase another PCI card as already
suggested :-)


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