2mo ago

GDM not honoring custom monitor config

So, for context, I have an HDMI dummy plug that is disabled most of the time, but enabled through command-line to use as a virtual display for game streaming with Sunshine.

In GNOME settings, the display is disabled, and that works just fine. I can enable/disable it at will whenever I want to stream games using the new gdctl utility added in GNOME 48.

I want this “monitor” to be disabled in GDM as well since it keeps trying to use the dummy plug as the default display and I can’t see any of the UI elements and have to type my password in blindly. I’ve copied over my monitor config from /home/user/.config/monitors.xml to /var/lib/gdm/.config/monitors.xml as per the Arch Wiki’s recommendations, but when I log out/reboot, nothing changes on GDM. It still tries to show the password entry UI on the dummy plug and my actual display just shows a gray screen.

I know the configs are different for X11 and wayland, but both GDM and GNOME are running under wayland, so that shouldn’t be the issue.

Any help would be appreciated.

I use Arch btw.

7 comments

When you copy over your monitor config, are you correcting the ownership/permissions?
The little scriptlet I made to combat a previous nvidia/wayland multi-monitor headache boils down to:
bash

sudo cp $HOME/.config/monitors.xml /var/lib/gdm/.config/ sudo chown gdm:gdm /var/lib/gdm/.config/monitors.xml
Maybe double check if GDM is ignoring wayland as well, I've definitely had that happen in the past too.
- Just checked the ownership of the monitor config, it was gdm:root, so I changed the ownership to gdm:gdm and rebooted. Still facing the same issue.
  Didn’t see any error messages in the logs about not being able to load wayland, but just to confirm, I ran loginctl show-session {gdm session id} -p Type which returns Type=wayland, so it’s definitely running under wayland. I have an AMD GPU though so I wouldn’t expect there to be any problems there.
  Not seeing anything else weird in the logs that are jumping out as strange to me either, so a bit at a loss here. Any other suggestions?
  
  Yeah, seems like it should just be working...
  You've probably already got this covered, but when you created your user monitors.xml config, did you have the dummy plug connected and disabled?
  Maybe the config:
  has it included as a monitor and enabled as part of the screen layout
  or possibly doesn't include it at all, and then GDM just assumes it can/should use it as a new option?

7 comments