Since you're using debian/ubuntu, check the existence of /etc/init.d/xdm
and /etc/rc2.d/xdm
, whereas the latter should be a symlink to the former. If the latter doesn't exist, you can make one, or use the rcconf
tool to create one.
P.S. Sorry I've never heard lightdm
, but the package xdm
itself should be working fine. And I don't think there's anything to do with the dmesg
information.