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When I boot Ubuntu, the system has the correct screen resolution until the login screen is displayed. It then temporarily changes to a much lower resolution and restores the original resolution after login.

As far as I understood, the login screen is realized with GDM (used to be LightDM). The posts I read so far recommend to put fix this directly in /etc/gdm3/Init/Default by adding the appropriate xrandr command right before exit 0, in my case xrandr --output XWAYLAND0 --primary --mode 2560x1440.

After reboot the login screen is still displayed in the wrong resolution or the zoom factor is doubled, which I cannot check.

As the recommended fix does not work: How can I check why it is not working and how can I fix this issue?

Vince42
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2 Answers2

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The mode you are trying to set may not be available to xrandr yet. In your /etc/gdm3/Init/Default, put the following also before the exit 0.

xrandr --newmode "2560x1440_60.00"  312.25  2560 2752 3024 3488  1440 1443 1448 1493 -hsync +vsync
xrandr --addmode XWAYLAND0 "2560x1440_60.00"
xrandr --output XWAYLAND0 --primary --mode "2560x1440_60.00"
exit 0
eskhool
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0

The display rendering most likely depends on your exact video card.

When the system boots is "auto" checks for very detailed features in some video cards and "not others?" Your video card is maybe much more then just the screen size? Some of these features are "generic" and usually can be read from memory address locations on the card AND others custom or problem video locations.

From what I hear there is kinda a debate between the passing of the old display driver system and the new so stability of how detailed info can truly be read from the video card is not always possible and people maybe needs to be "translated". You can maybe contact the owner of the video driver for your card? Of post some more detailed info.

Thanks!

Asher
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