etc/init/gdm.conf

# gdm - GNOME Display Manager
#
# The display manager service manages the X servers running on the
# system, providing login and auto-login services

description	"GNOME Display Manager"
author		"William Jon McCann <mccann@jhu.edu>"

start on (filesystem
          and started dbus
          and (drm-device-added card0 PRIMARY_DEVICE_FOR_DISPLAY=1
               or stopped udev-fallback-graphics))
stop on runlevel [016]

emits login-session-start
emits desktop-session-start

env XORGCONFIG=/etc/X11/xorg.conf

script
    if [ -n "$UPSTART_EVENTS" ]
    then
	[ ! -f /etc/X11/default-display-manager -o "$(cat /etc/X11/default-display-manager 2>/dev/null)" = "/usr/sbin/gdm" ] || { stop; exit 0; }

	# Check kernel command-line for inhibitors
	for ARG in $(cat /proc/cmdline)
	do
	    case "${ARG}" in
		text|-s|s|S|single)
		    plymouth quit || :  # We have the ball here
		    exit 0
		    ;;
	    esac
	done
    fi

    if [ -r /etc/default/locale ]; then
	. /etc/default/locale
	export LANG LANGUAGE
    elif [ -r /etc/environment ]; then
	. /etc/environment
	export LANG LANGUAGE
    fi
    export XORGCONFIG

    exec gdm-binary $CONFIG_FILE
end script