On Samstag, 11. März 2023, 13:03:41 CET Alexander Puchmayr wrote:
> Hi there,
>
> After having done a world update, neither sddm nor lightdm do start an
> Xserver anymore. The X server itself runs fine, I can start it from the
> console and I after setting DISPLAY properly can even start programs using
> it, but the login managers do not start X for some reason.
>
> No hint so far in the logs, and no ideas where I should looking.
>
> The system is running inside a virtualbox VM, with Win10 as host operating
> system.
>
Its even getting more strange, the very same image copied from the windows
laptop to a linux box and started with kvm/libvirt works fine, but in windows/
virtualbox it doesn't.
Now I have two completely identical systems which only differn in the
hypervisor they're started with, named "virtualbox" and "libvirt". On both
systems, I start lightdm from the command line with -d option, and compare the
results.
Intrestingly the "libvirt" system writes "New seat added from logind: seat0",
the "virtualbox" system does not, which seems to be the relevant difference
(see log output below)
Further, I found the following command in another forum:
Gdbus introspect --system --dest org.freedesktop.login1 --object-path /org/
freedesktop/login1/seat/seat0
And the relevant difference here is in the org.freedesktop.login1.Seat
properties section
...
readonly b CanGraphical = false;
...
on virtualbox. The same command on "libvirt" machine shows "true" here.
So, what is required for a login seat to be treated as "graphical"?
Thanks
Alex
[virtualbox] # lightdm -d
[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.32.0, UID=0 PID=867
[+0.00s] DEBUG: Loading configuration dirs from /usr/share/lightdm/
lightdm.conf.d
[+0.00s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/
lightdm.conf.d
[+0.00s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d
[+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Registered seat module local
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.01s] DEBUG: _g_io_module_get_default: Found default implementation local
(GLocalVfs) for ?gio-vfs?
[+0.01s] DEBUG: Using cross-namespace EXTERNAL authentication (this will
deadlock if server is GDBus < 2.73.3)
[+0.02s] DEBUG: Monitoring logind for seats
[+0.02s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.02s] DEBUG: Could not run plymouth --ping: Failed to execute child process
?plymouth? (No such file or directory)
[+0.02s] DEBUG: Loading users from org.freedesktop.Accounts
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User2001 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1001 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User2002 added
...waiting for ctrl-C and no login screen ...
[libvirt] # lightdm -d
[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.32.0, UID=0 PID=793
[+0.00s] DEBUG: Loading configuration dirs from /usr/share/lightdm/
lightdm.conf.d
[+0.00s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/
lightdm.conf.d
[+0.00s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d
[+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Registered seat module local
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Using cross-namespace EXTERNAL authentication (this will
deadlock if server is GDBus < 2.73.3)
[+0.00s] DEBUG: _g_io_module_get_default: Found default implementation local
(GLocalVfs) for ?gio-vfs?
[+0.01s] DEBUG: Monitoring logind for seats
[+0.01s] DEBUG: New seat added from logind: seat0
[+0.01s] DEBUG: Seat seat0: Loading properties from config section Seat:*
[+0.01s] DEBUG: Seat seat0 has property CanMultiSession=no
[+0.01s] DEBUG: Seat seat0: Starting
[+0.01s] DEBUG: Seat seat0: Creating greeter session
[+0.01s] DEBUG: Seat seat0: Creating display server of type x
[+0.01s] DEBUG: Could not run plymouth --ping: Failed to execute child process
?plymouth? (No such file or directory)
[+0.01s] DEBUG: Using VT 7
[+0.01s] DEBUG: Seat seat0: Starting local X display on VT 7
[+0.01s] DEBUG: XServer 0: Logging to /var/log/lightdm/x-0.log
[+0.01s] DEBUG: XServer 0: Writing X server authority to /var/run/lightdm/
root/:0
[+0.01s] DEBUG: XServer 0: Launching X Server
[+0.01s] DEBUG: Launching process 799: /usr/bin/X :0 -seat seat0 -auth /var/
run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.01s] DEBUG: XServer 0: Waiting for ready signal from X server :0
[+0.01s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.01s] DEBUG: Registering seat with bus path /org/freedesktop/
DisplayManager/Seat0
[+0.01s] DEBUG: Loading users from org.freedesktop.Accounts
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User2001 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1001 added
[+0.18s] DEBUG: User /org/freedesktop/Accounts/User2002 added
[+0.40s] DEBUG: Got signal 10 from process 799
[+0.40s] DEBUG: XServer 0: Got signal from X server :0
[+0.40s] DEBUG: XServer 0: Connecting to XServer :0
[+0.40s] DEBUG: Seat seat0: Display server ready, starting session
authentication
[+0.40s] DEBUG: Session pid=815: Started with service 'lightdm-greeter',
username 'root'
[+0.55s] DEBUG: Session pid=815: Authentication complete with return value 0:
Success
[+0.55s] DEBUG: Seat seat0: Session authenticated, running command
[+0.55s] DEBUG: Session pid=815: Running command /usr/sbin/lightdm-gtk-greeter
[+0.55s] DEBUG: Creating shared data directory /var/lib/lightdm-data/root
[+0.55s] DEBUG: Session pid=815: Logging to /var/log/lightdm/seat0-greeter.log
[+0.55s] DEBUG: Activating VT 7
[+0.81s] DEBUG: Greeter connected version=1.32.0 api=1 resettable=false
[+1.40s] DEBUG: Greeter start authentication for alex
[+1.40s] DEBUG: Session pid=855: Started with service 'lightdm', username
'alex'
[+1.41s] DEBUG: Session pid=855: Got 1 message(s) from PAM
[+1.41s] DEBUG: Prompt greeter with 1 message(s)
