Today I made another experiment. I've changed the PCI slot position of the nvidia graphic cards and I've changed the gpu that should be used as default from the BIOS from the intel gpu to the geforce 1060 gpu. Actually I'm using this xorg.conf :
https://pastebin.ubuntu.com/p/DhW6RHS3zb/
instead this is the Xorg.0.log file :
https://pastebin.ubuntu.com/p/YtdPq9fngQ/
In front of me I have the AOC monitor,that's connected to the HDMI port of the 1060. On my right I have the monitor samsung synchmaster,that's connected to the HDMI port of the intel GPU. The 3 gpu (rtx 2080 ti is non connected to any monitor because I want to use it to be passed thru on a bhyve vm.
What happens is that the samsung monitor works partially. The only 2 apps which can be directed to it (it is attached to the Intel GPU with the HDMI cable) are :
[marietto@marietto ~]$ export DISPLAY=:0.1 ; konsole
and :
[marietto@marietto ~]$ export DISPLAY=:0.1 ; chrome
(firefox can be displayed only on the screen 0 : don't know why)
Here you can find the list of every PCI device attached to my PC :
https://pastebin.ubuntu.com/p/Gx5DqckFQP/
what else ? the samsung synchmaster screen always worked partially. When I told you that it didn't work was because I didn't know that I could export some application to the DISPLAY=:0.1. But anyway,even in this case,this kind of usage is not comfortable at all. I can't run another session of xorg because it says that one session is already running. Only some applications are displayed on the secondary screen (samsung synchmaster + intel GPU). And If I invert the cable and the drivers on xorg.conf,placing as primary gpu the intel gpu attached to the AOC monitor and as secondary gpu the nvidia 1060 attached to the samsung synchmaster,the behavior is the same,with the difference that I've inverted the monitors. I've tried to enable xinerama,but it does not work good. It freezes the mouse and anyway,attaching virtually two screens into only one is ridicolous,because they aren't attached physically.
# xrandr -q
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
DVI-D-0 disconnected (normal left inverted right x axis y axis)
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 598mm x 336mm
1920x1080 60.00*+ 59.94 50.00 60.00 50.04
1680x1050 59.95
1440x900 59.89
1280x1024 75.02 60.02
1280x960 60.00
1280x720 60.00 59.94 50.00
1024x768 75.03 70.07 60.00
800x600 75.00 72.19 60.32 56.25
720x576 50.00
720x480 59.94
640x480 75.00 72.81 59.94 59.93
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 disconnected (normal left inverted right x axis y axis)
DP-5 disconnected (normal left inverted right x axis y axis)
arandr tells that the only monitor connected is the HDMI-0,the monitor AOC connected to the nvidia 1060 gpu. But if I invert the drivers on xorg.conf and the cables,the only monitor connected will be again the HDMI-0,but this time it will be the Samsung Synchmaster.