sddm
overlaying sddm on multiple screen setup with differing resolutions
I have a triple screen setup with a 1280x1024 screen on the left, a 1920x1080 screen in the center and another 1280x1024 screen on the right. One thing is the super tiny font since sddm 0.14 (see #692). Another thing is, that on the center screen I have two overlaying SDDMs, one with 1280x1024 in the foreground and one with 1920x1080 in the background.
I have a dual monitor setup with 1024x768 on the left and 1920x1080 on the right and the exact same thing happens. On openSUSE Tumbleweed I edited /etc/X11/xdm/Xsetup and added:
/usr/bin/xrandr --output VGA1 --off
After:
. /etc/sysconfig/displaymanager
All this does is disable the 1024x768 monitor before sddm starts up, so when it does, it only has one output (just like in a single monitor setup). The files may be different on other distros, and It's only a workaround, this issue has been around for a long time, I remember it happening on OpenSUSE LEAP 42.1 when It released (November 4, 2015).
I can reproduce this bug on Fedora 25 (sddm 0.14), left monitor has 1920x1080, right one 1680x1050.
I got it working as intended by ditching xf86-video-intel in favor of xf86-video-modesetting, not sure if the other reports were using an intel GPU though.
Same here with xf86-video-intel and a three monitor setup: 4k, 1080p, 1080p. The third display is showing up on top of the first display.
For Arch based users (including Manjaro) the Arch wiki has a simple workaround: https://wiki.archlinux.org/title/SDDM#Overlapping_greeters_on_multiscreen_setup
first, run "sudo nano /usr/share/sddm/scripts/Xsetup" and then add the following:
for next in $(xrandr --listmonitors | grep -E " [0-9]+:." | cut -d" " -f6); do [ -z "$current" ] && current=$next && continue xrandr --output $current --auto --output $next --auto --right-of $current current=$next done
I use a similar Xsetup workaround on my multi-monitor dual-GPU setup. Today I upgraded to sddm-git to give the wayland version a try, and rediscovered the same issue there. The two monitors connected to the iGPU show an overlapping sddm. The monitor connected to the dGPU stays black. Of course on wayland it is not as easy to hard-code the display setup I want with an xrandr script, so I had to revert back to the X11 version of sddm for now.
I use a similar Xsetup workaround on my multi-monitor dual-GPU setup. Today I upgraded to sddm-git to give the wayland version a try, and rediscovered the same issue there. The two monitors connected to the iGPU show an overlapping sddm. The monitor connected to the dGPU stays black. Of course on wayland it is not as easy to hard-code the display setup I want with an xrandr script, so I had to revert back to the X11 version of sddm for now.
This is still a problem in version 0.20. With X I can workaround this, with wayland this is not possible. I can sync the settings from KDE, which according to the pop-up should also synchronize display settings but this does not appear to work. It would be great if there was some setting to just disable multi-monitor so SDDM shows on just one, even if that is the incorrect one it is still better then this overlapping ugliness.
With the latest full system update my issue has fixed itself and sddm is working nicely on all monitors. Sddm itself was not updated, so perhaps the problem was somewhere else to begin with, e.g. kwin(_wayland)/kscreen. Among other things the KDE stuff was updated, but I can't be sure what fixed this exactly.