I have a Red Hat 5 64 bits PC with 2 QUADRO FX 3800.
I use a software A that renders images in an off-screen buffer. When A starts, it opens a useless black xwindow, which is attached to a display, which is attached to a graphics hardware.
In order to avoid having this xwindow beeing open and visible on the main desktop, I thought we could set the DISPLAY environment variable (X display) to something different from :0.0 before running A from a terminal.
So I have connected 2 monitors to one of the graphics cards, and a third monitor to the second graphics card, generated the xorg.conf with "nvidia-xconfig --enable-all-gpus --separate-x-screens",restarted the X server, and could check that I could run A on the second monitor by opening a terminal from the main monitor, setting DISPLAY to :0.1 and run A. Idem for the third monitor and DISPLAY set to :0.2. I could still do it after unplugging the 2nd and 3rd monitors. --> success
However, when I restarted the X server with the 2 second monitors unplugged, the DISPLAY :0.1 and 0.2 could not be opened anymore. --> failure
I suspect that the displays are created by the X server at startup time. So I tried different configurations of the xorg.conf such as MonitorConnected, UseEDID. But none of them allowed me to have :
- Linux PC starts with 2 graphics cards + 1 Monitor connected to one of the 2 graphics cards
- The following DISPLAYS can be open :0.0, :0.1, :0.3 such as
:0.0 displays to the monitor and is attached to graphics card 1
:0.1 displays to NO monitor and is attached to graphics card 1
:0.2 displays to NO monitor and is attached to graphics card 2
Please help !