File X11-displaymanager-gdm of Package gdm
gdm_vars() {
case "${DISPLAYMANAGER##*/}" in
gdm|GDM|Gnome|GNOME)
RELOADSIGNAL="-USR1"
DISPLAYMANAGER=/usr/sbin/gdm
PIDFILE=/run/gdm/gdm.pid
# let gdm run the Xserver as root if access to /dev/fb*
# is required (bsc#1075805)
# The GDM_DISABLE_USER_DISPLAY_SERVER variable is added by patch
# gdm-add-runtime-option-to-disable-starting-X-server-as-u.patch
if [ ! -c /dev/dri/card0 -a \
! -c /dev/nvidiactl ]; then
export GDM_DISABLE_USER_DISPLAY_SERVER=1
fi
return 0 ;;
*) return 1 ;;
esac
return 1
}