By default there is not persisted /etc/X11/xorg.conf. The settings are dynamically determined during boot up. I wanted to turn on the dbe module.
- Drop to the terminal by doing ctrl+alt+F1
- Login as root
- Stop gdm3; “service gdm3 stop“
- Configure x; “Xorg -configure“
- Copy xorg.conf into /etc/X11; “cp xorg.conf /etc/X11/xorg.conf“
- Start x; “service gdm3 start“