On my laptop (Kubuntu 23.04), GRUB uses the entire screen (1600x900), as does SDDM and the Desktop. However, KDE neon 5.27, running in an Oracle VM on my Apple iMac, the GRUB menu and SDDM windows aren't using the resolution I configured for the Desktop; both are smaller (and both windows are different sizes). Is it possible (I'd think it was), and how does one go about, getting GRUB and SDDM to use the same resolution as I've specified for the Desktop?
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Using Kubuntu Linux since March 23, 2007
"It is a capital mistake to theorize before one has data." - Sherlock Holmes
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I am guessing the virtualized BIOS or UEFI reports one value that Grub uses, then the completely separate X11 session that SDDM uses gets a resolution from who knows where, and finally the desktop session uses the system's detected X11/Wayland resolution.
You will need to set a resolution in grub and SDDM to match.
Probably an artifact from using virtualized hardware. I see this in most cases on the VMs I run using virt-manager (qemu/kvm) as well. I haven't been able to 'fix' this tweaking virtual hardware settings, and my desktop doesn't have an iGPU to pass through to virt-manager. I have spent minimal effort on the topic, though.
For grub, you can set one by adding/modifying GRUB_GFXMODE=640x480 , or whatever to match your desktop session
Which will of course change if you resize the VM window, thus making grub no longer match.
You may need to run vbeprobe in a grub command line to see what is supported in your VM (hit 'c' at the grub menu)
SDDM can be set to use a custom setup by passing the appropriate xrandr command to match.
Add that to /usr/share/sddm/scripts/Xsetup
(I *think*. I used a custom config top only use one monitor at SDDM back when I was using X11. There are other file locations, including /etc/sddm.d/ where one can add custom config stuff, but I cannot recall which one worked for me.)
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