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I'm having trouble with screen resolution on Ubuntu 20.04 with an HP 2009v monitor, which has native resolution 1600x900 pixels.

Problem is that when I startup the computer (with integrated Intel graphics), monitor says that received resolution is out of range, displaying nothing. With some troubles, I managed to set right resolution in user session with xrandr commands. Now I'd like to set proper resolution at least at login screen, then possibly to the grub bootloader too.

I edited the /etc/gdm3/Init/Default file adding following lines, but nothing changed:

xrandr --newmode "1600x900_60.00"  118.25  1600 1696 1856 2112  900 903 908 934 -hsync +vsync
xrandr --addmode HDMI-3 1600x900_60.00
xrandr --output HDMI-3 --mode 1600x900_60.00

I also copied ~/.config/monitors.xml to /var/lib/.config and nothing changed too

How could I set proper display resolution at login screen?

Furthermore, I'd need to set proper resolution at grub and during ubuntu startup. I edited /etc/default/grub adding the lines

GRUB_GFXMODE=1600x900
GRUB_GFXPAYLOAD=1600x900

but nothing changed here too. Display keep saying that input is out of range.

How can I troubleshoot this issue?

  • I suspect (don't ask me why) that this issue has something to do with framebuffer resolution. If I enter the command "cat /sys/class/graphics/fb0/modes" the output is just: U:1920x1080p-0. Which is actually wrong. Is there a way to tell my computer that those resolution is not supported by my display? – Matteo Jul 11 at 16:05
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As to the login screen: try a static X11 configuration by creating a file /etc/X11/xorg.conf.d/10-monitor.conf with content such as

Section "Device"
  Identifier "Configured Video Device"
  Driver "intel"
EndSection

Section "Monitor"
  Identifier  "Configured Monitor"
EndSection

Section "Screen"
  Identifier "Configured Screen"
  Device "Configured Video Device"
  Monitor "Configured Monitor"
  SubSection "Display"
    Modes "1600x900" "640x480"
  EndSubSection
EndSection

Useful web page: https://wiki.ubuntu.com/X/Config/Resolution

As to the grub screen: did you consult the grub info file?

| improve this answer | |
  • Should that filepath be /usr/share/X11/xorg.conf.d/? – John Mee Jul 15 at 14:23
  • Given the choice, system-wide configuration changes should be done under /etc, where they are less likely to be overwritten on upgrades. In my tests, the configuration file under /etc/X11/xorg.conf.d/ was picked up. – Siep Jul 15 at 14:42
  • My ubuntu does not have it. Did you create that directory yourself /etc/X11/xorg.conf.d/? – John Mee Jul 15 at 22:35
  • I do not remember now whether it was there or whether I created it. – Siep Jul 16 at 16:26
  • @Siep, wouldn't I need to edit a gdm3 config file rather than an X one? /etc/X11 is empty. Should I create the directory xorg.conf.d and create the config file as you suggested? I'm suspecting that this won't change anything, but I will give it a try. – Matteo Jul 20 at 21:20

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