Comment 3 for bug 1968943

Unfortunately, xrandr does not behave as expected when run on XWayland. Namely, if you select a lower resolution, xrandr on Wayland will only list this resolution as the maximum, so xrandr cannot be used to grab the max resolution on Wayland.

I started playing with /sys/class/drm/card*/modes files that contain a list of supported resolutions for each monitors, and it seems to be working fine, but using this method, it's impossible to know what entry is the primary monitor.

After discussing with Sylvain, it seems that the gnome-randr tool we are using on 22.04 is compatible with X, and could be backported to 20.04 to get

- max resolution
- primary monitor

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Another thing I'm wondering is... do we really need this complicated test?

We could just extract the max resolution for each screen connected to the device, show that to the tester, and ask them to manually verify (as it's already the case anyway)