Light-DM not used after upgrade 11.04→11.10

[Paul Sladen]

After the restart step of an upgrade →11.10 LightDM was not used, but GDM still continues to be used.

[Sebastien Bacher (seb128)]

is that a bug? there is no configuration migration between those dms not feature parity, should user forced on a stock dm config which might not match their needs?

[Robert Ancell (robert-ancell)]

I think we do want this to occur if possible:
- ubuntu-desktop should depend on unity-greeter and so lightdm should be installed
- lightdm should be the default display manager and the user shouldn't be prompted
- the only setting that needs to be migrated is the default user. Talked with Didier in Berlin about how to do this.

[Axel Pospischil (apos)]

There is more annoying to tell about this:

I also upgraded from natty to oneiric. My system with nvidia-current (280.13) even won't login, if i use lightdm.

During the installation process, i had been asked which manager to use. I'd chosen lightdm. That left me with an unusable system, because the xserver went into an infinite loop. Only if i switch to use gdm (dpkg-reconfigure lightdm), xserver starts.

See: https://bugs.launchpad.net/ubuntu/+source/nvidia-settings/+bug/840462

[Maxim Bublis (mbublis-deactivatedaccount)]

I guess problem with starting up lightdm after plymouth is in misconfiguration.

$ cat /etc/init/lightdm.conf

... SKIPPED ...

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

 if [ "$RUNLEVEL" = S -o "$RUNLEVEL" = 1 ]
 then
     # Single-user mode
     plymouth quit || :
     exit 0
 fi
    fi

    exec lightdm
end script

... SKIPPED ...

It checks if there is "/usr/bin/lightdm" or "/usr/sbin/lightdm" in /etc/X11/default-display-manager, but in my case it's "lightdm" in that file:

$ cat /etc/X11/default-display-manager
lightdm

[Maxim Bublis (mbublis-deactivatedaccount)]

In my opinion proper patch to lightdm.upstart should be

to replace:
[ ! -f /etc/X11/default-display-manager -o "$(cat /etc/X11/default-display-manager 2>/dev/null)" = "/usr/bin/lightdm" -o "$(cat /etc/X11/default-display-manager 2>/dev/null)" = "/usr/sbin/lightdm" ] || { stop; exit 0; }

with:
[ ! -f /etc/X11/default-display-manager -o "$(echo $(basename $(cat /etc/X11/default-display-manager 2>/dev/null)))" = "lightdm" ] || { stop; exit 0; }

[Tuukka Hastrup (tuukkah)]

I hit the bug mentioned in comments #4 and #5 -- filed as bug #864174.

[Robert Ancell (robert-ancell)]

These releases are now unsupported.