[LightDM] Can LightDM work with an existing X server socket?

[Robert Ancell]

That looks correct.

The log is a bit confusing, the LightDM daemon is starting a "display
server" but in fact it's just creating the object for the remote display
server. The daemon is then trying to connect to that X server and failing
which is why it stops.

This is basically the equivalent of running something like:
$ DISPLAY=desktop/unix:6 glxinfo

So check if that works.



On 15 November 2013 06:29, Shahim Essaid <shahim at essaid.com> wrote:

> Robert,
>
> I tried the configuration you suggested but there must be something
> else I am missing.
>
> I'm trying this in Ubuntu 13.10 64 bit with LightDM 1.8.4. My host
> name is "desktop".  I have the socket as /tmp/.X11-unix/X6 and if I
> do:
>
> export DISPLAY=:6
> xterm
>
> I get the xterm window on the display. I have access control disabled
> in X for now.
>
> I started with the LightDM configuration you suggested and then added
> few more lines to make the server name look right in the logs. Here is
> my configuration and the error in the log:
>
>
> [LightDM]
> start-default-seat=false
> minimum-display-number=6
> minimum-vt=6
>
> [Seat:6]
> type=xremote
> xserver-display-number=6
> xserver-share = true  # I had the same error without this line and the
> next one
> xserver-hostname = desktop/unix # without this the display name would
> be localhost:6
>
> [+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
> [+0.00s] DEBUG: Starting Light Display Manager 1.8.4, UID=0 PID=984
> [+0.00s] DEBUG: Loading configuration from
> /etc/lightdm/lightdm.conf.d/10-ubuntu.conf
> [+0.00s] DEBUG: Loading configuration from
> /etc/lightdm/lightdm.conf.d/50-greeter-wrapper.conf
> [+0.00s] DEBUG: Loading configuration from
> /etc/lightdm/lightdm.conf.d/50-guest-wrapper.conf
> [+0.00s] DEBUG: Loading configuration from
> /etc/lightdm/lightdm.conf.d/50-unity-greeter.conf
> [+0.00s] DEBUG: Loading configuration from
> /etc/lightdm/lightdm.conf.d/50-xserver-command.conf
> [+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
> [+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
> [+0.00s] DEBUG: Using Xephyr for X servers
> [+0.00s] DEBUG: Registered seat module xlocal
> [+0.00s] DEBUG: Registered seat module xremote
> [+0.00s] DEBUG: Registered seat module unity
> [+0.00s] DEBUG: Registered seat module surfaceflinger
> [+0.00s] DEBUG: Loading seat Seat:6
> [+0.00s] DEBUG: Seat 6: Starting
> [+0.00s] DEBUG: Seat 6: Creating greeter session
> [+0.00s] DEBUG: Seat 6: Setting XDG_SEAT=seat0
> [+0.00s] DEBUG: Seat 6: Creating display server of type x
> [+0.00s] DEBUG: Seat 6: Starting remote X display desktop/unix:6
> [+0.00s] DEBUG: DisplayServer x-desktop/unix-6: Connecting to XServer
> desktop/unix:6
> [+0.00s] DEBUG: DisplayServer x-desktop/unix-6: Error connecting to
> XServer desktop/unix:6
> [+0.00s] DEBUG: Seat 6: Can't create display server for greeter
> [+0.00s] DEBUG: Seat 6: Session stopped
> [+0.00s] DEBUG: Seat 6: Stopping; failed to start a greeter
> [+0.00s] DEBUG: Seat 6: Stopping
> [+0.00s] DEBUG: Seat 6: Stopping display server
> [+0.00s] DEBUG: Seat 6: Display server stopped
> [+0.00s] DEBUG: Seat 6: Stopped
> [+0.01s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
>
>
> From the log it looks like LightDM is trying to start a new display.
> Any thoughts about what I am doing wrong?
>
> Thanks,
> Shahim
>
>
> On Wed, Nov 13, 2013 at 8:17 PM, Robert Ancell <robert.ancell at gmail.com>
> wrote:
> > Hi Shahim,
> >
> > You should be able to configure LightDM to use an existing X server using
> > the following configuration:
> >
> > [SeatDefaults]
> > type=xremote
> > xserver-display-number=0
> >
> > i.e. if you already have an X server running on :0
> >
> > --Robert
> >
> >
> > On 14 November 2013 11:56, Shahim Essaid <shahim at essaid.com> wrote:
> >>
> >> Hi all,
> >>
> >> I'm setting up an LXC container for Ubuntu 13.10 where the X server is
> >> started in the host on vt6. The unix socket and authority file are
> >> then mounted in the LXC container. I can start X sessions and
> >> applications from the container but I can't get LightDM to use this
> >> server.
> >>
> >> I would really like to have the container's LightDM/Ubuntu greeter to
> >> automatically start on this display when the container is started to
> >> allow a graphical login. I'm aware of other options (XDMCP, vnc, etc.)
> >> but I'm trying to do it directly through the mounted unix domain
> >> socket. I've been trying to configure X to be started and managed by
> >> LightDM in the container but haven't been able to do that so far.
> >>
> >> Is this possible?
> >>
> >> Thank you,
> >> Shahim
> >> _______________________________________________
> >> LightDM mailing list
> >> LightDM at lists.freedesktop.org
> >> http://lists.freedesktop.org/mailman/listinfo/lightdm
> >
> >
>
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