When we're using server managed-fds through systemd-logind, systemd-logind
*must* keep running while we are using it, as it does things like drmSetMaster
and drmDropMaster for us on vt-switch.
On a systemd-logind restart, we cannot simply re-connect since we will then
get a different fd for the /dev/dri/card# node, and we've tied a lot of
state to the old fd. I've discussed this with the systemd people, and in the
future there may be a restart mechanism were systemd-logind passed fds from
the old logind to the new logind. But for now there answer is simply:
"Don't restart systemd-logind", and there never really is a good reason to
restart it.
So to ensure unpleasentness if people do decide to restart systemd-logind
anyways (or when it crashes), monitor logind going away and make this a fatal
error. This avoids getting a hard-hung machine on the next vt-switch and will
hopefully quickly educate users to not restart systemd-logind while they have
an X session using it active.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
dc48bd653c