Linux multi-gpu / desktop support

Graphics / Linux Linux
1

Originally posted on wrong forum, chat support told me to try here.

I’m currently setting up a dual booted system with Windows 10 / Linux (Debian). I have a multiple GPU system, a GTX1660Ti and a GTX760. The 1660 runs two monitors and the 760 runs a monitor and TV.

After installing Linux and installing the nvidia-driver I found that in the default desktop settings only two monitors where being shown. When looking in the nvidia-settings application I can see both cards and all monitors.

I’ve been trying to use the x configuration dialog to get a setup that works but at best I end up with the 1660 (and monitors) showing the desktop and the 760 monitors only showing a cursor (a cross).

I’ve tried Xinerama (forgive spelling) but this ends up with a black screen across all displays.

Looking to google/reddit/rest of the internet it’s filled with frustrated people and the gist of most is “give up this is a nightmare”.

Can you provide me a definitive yes/no answer, can Linux (Debian or any flavour) support the setup I’ve described above? I’ve already spent close to a week investigating this, multiple reinstallations / configurations and I’ve been left pulling my hair out (which i have very little left).

If there is a solution, I’d be very grateful if you could provide a process/procedure?

If not are there plans to address this in future, would seem like a strange oversight. I’m very keen to ditch Windows and move to Linux (sick of the direction Windows is going in ala Fisherprice OS / copying Apple). With Steam now putting effort into making games work in Linux I’m keen to give it a try but have run into this problem at the first hurdle.

EDIT: From what I’ve read Xorg/X11 may never support this but the upcoming “Wayland” display manager should? Also noticed that it’s requested i supply logs, however my current install of Debian is bricked after the latest attempt to get things working. If requested/needed I’ll supply logs once i’ve reinstalled/retested.

Hoping for a solution,

Simon

2

Xinerama is a (really crap) possibility that has been largely deprecated. The “correct” way to do this is to pick one GPU as “primary” (the Device in the screen section) and have the other one be a GPUDevice. Then with “xrandr --listproviders” should list both. You can then tell the system to use the second card as outputsink using “xrandr --setprovideroutputsource 1 0”. This works if one of the cards is an intel (GPU) card, but as Nvidia supports both directions, it may work with both nvidia cards as well.

3

Thanks, I’ll give this a whirl tomorrow and update.

4

@paul.devrieze Is this still true in 2023?
Could you provide any resources detailing how one might set the second GPU as a “GPUDevice” ?