Changing brighness via shortcut fails to change screen brighness

[deeplow]

The solution was found on this other thread:

How to apply grub command line parameters for backlight brightness to Qubes OS?

For 4.0, the difference depends on whether it is installed with legacy mode or UEFI mode. In the former mode, grub is will be used but not in the latter, so that that file is not exists but there is another one called xen.cfg instead. [root@dom0 ~]# cat /boot/efi/EFI/qubes/xen.cfg [global] default=5.4.98-1.fc25.qubes.x86_64 [5.4.98-1.fc25.qubes.x86_64] options=loglvl=all dom0_mem=min:1024M dom0_mem=max:4096M iommu=force ucode=scan smt=off kernel=vmlinuz-5.4.98-1.fc25.qubes.x86_64 root=/dev/map…