In a more pure development environment, I can confirm this bug without
needing hybrid GPUs, or gdm3.
Just the Nvidia driver and Xorg results in no outputs/monitors detected:
$ xrandr
Screen 0: minimum 8 x 8, current 640 x 480, maximum 16384 x 16384
To work around the problem I need to run Xorg as root. Then I get:
$ xrandr
Screen 0: minimum 8 x 8, current 1920 x 1200, maximum 16384 x 16384
DVI-I-0 disconnected primary (normal left inverted right x axis y axis)
DVI-I-1 disconnected (normal left inverted right x axis y axis)
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x
324mm
1920x1200 59.95*+ 59.88
1920x1080 60.00 59.94 50.00 23.98
1600x1200 60.00
1280x1024 75.02 60.02
1280x720 60.00 59.94 50.00
1152x864 75.00
1024x768 75.03 60.00
800x600 75.00 60.32
720x576 50.00
720x480 59.94
640x480 75.00 59.94 59.93
So perhaps gdm3 is sometimes missing whatever /dev/* privileges it needs
to start Xorg on Nvidia properly. And perhaps lightdm just always does
it right.
Although a solution here in the medium term might lay in gdm3, I would
more like to see the Nvidia driver fix this bug. Because I can reproduce
it without any *dm. Just the kernel + Nvidia driver + Xorg.
** Changed in: gdm3 (Ubuntu)
Status: Confirmed => Opinion
** Changed in: mutter (Ubuntu)
Status: Confirmed => Invalid
** Also affects: nvidia-graphics-drivers-418 (Ubuntu)
Importance: Undecided
Status: New
** Changed in: nvidia-graphics-drivers-418 (Ubuntu)
Status: New => Confirmed
** Also affects: nvidia-graphics-drivers-375 (Ubuntu)
Importance: Undecided
Status: New
** Changed in: nvidia-graphics-drivers-375 (Ubuntu)
Status: New => Confirmed
** Summary changed:
- gdm3, hybrid nvidia with modeset=1, no external monitors detected
+ nvidia-drm.modeset=1 results in no monitors detected by Xorg
** Changed in: gdm3 (Ubuntu)
Status: Opinion => Invalid
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https://bugs.launchpad.net/bugs/1716857
Title:
nvidia-drm.modeset=1 results in no monitors detected by Xorg
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