I'm running an nvidia card on X11 Plasma 6, with a 4K monitor alongside a QHD monitor. Both monitors are the same physical size, despite being different resolutions, so in the nvidia settings app, I've got the second X screen setup to generate 4K but downscale it to QHD in the output. It makes the second screen slightly blurry, but it's worth it for the ability to move windows back and forth without dealing with different resolutions.
The problem is, no matter what I do, I can't make the changes "stick". The nvidia applet has an option to save it to the x.conf file, and I've verified that it has done so in a text editor. But every time I boot, I have to change it in the nvidia settings applet again.
Is there something I'm missing with the way arch/kde handles x conf files? How do I make it stick between reboots?
Are the X config files being deleted or changed on boot, or are they still there?
After updating nvidia-settings, the x conf looks correct and reads like this
Option "metamodes" "DP-2: nvidia-auto-select +0+0 {ForceCompositionPipeline=On, ForceFullCompositionPipeline=On}, DP-0: nvidia-auto-select +3840+132 {viewportin=3840x2160, ForceCompositionPipeline=On, ForceFullCompositionPipeline=On}"But then when I reboot, it reads as follows
Which is to say the correct line is commented out, and the incorrect version replaces it.
I can't work out how or why that is happening though
Ok, with further digging, I discovered that it was only getting updated on user login. The actual login screen itself was running with the updated resolution. So something in the KDE login process was to blame.
My girlfriend did some research, and it turns out that KDE kscreen service is the problem. I've disabled that, and everything works now
Might be worth reporting that as a bug? Seems wrong that kscreen can parse the X config file, and silently throw out lines it doesn't understand. Should at least pop up an error or "do you want to reset this" dialog box if possible. Good outcome though.
Is it a bug? It feels like commenting out the previous line is a deliberate design choice?
A deliberate design choice can still be a bug. I suspect they would just close the bug report, but at least they would be aware of your use case?
OK, I logged a bug