Re: [gdm-list] FailsafeXServer - gdm keeps restarting X

[Brian Cameron <Brian Cameron Sun COM>]

Bryce:

Looking at the logs, it seems that every time GDM tries to start an
XServer that it is hitting the following error:

Aug 28 12:04:12 dorset gdm[5348]: WARNING: gdm_slave_xioerror_handler: Fatal X 
error - Restarting :0

I think you need to track down what is causing the X IO error, and see if
the problem is in the way that GDM is handling things, or if the X IO
error can be avoided.

Brian

> > Note that when FailsafeXServer is set, then it sets d->command to the
> > failsafe X server command.  Then in server.c, in gdm_server_spawn it
> > will run that command.  Note it also has gdm_debug lines so that the
> > command it runs should get logged.  Can you verify that the Xserver
> > is trying to run your failsafe command or not?  Is your failsafe command
> > failing, or is the GDM mechanism to reset the command to the failsafe
> > one not working?
>
> Hi Brian, the failsafe command is definitely running and working
> correctly.  However, after about 1 minute, gdm appears to be trying to
> start another session, and it's this second session where the failure
> occurs.
>  
> > Turn on debug in the configuration file and try to start GDM and let
> > us know what gdm related messages get added to the end of your syslog
> > (/var/log/messages or /var/adm/messages).
>
> I've excerpted the gdm portion of /var/log/syslog from gdm restart up to
> the first time it tried to crease a second session.
>  
> > Based on the message that you are getting "There already appears to
> > be an X server running on display :0" indicates to me that the first
> > server might not have crashed completely or left the system in a state
> > where the failsafe Xserver is failing to start?  This could be a
> > problem with the Xserver or with the way GDM detects if the Xserver
> > is already running or not.  This message gets displayed when the
> > Xserver claims it is "busy".  
>
> I've attached output from 'ps aux | grep -i x' from right after the
> failsafe mode has started, again after the whiptail message popped
> up, and then a third after I've stopped gdm and killed all the xinit and
> whiptail processes.  I notice that there is a zombie Xorg process shown
> - I take it this must be the original failed Xserver?
>
> > It looks like in the function
> > display_busy in server.c that the code is looking at the
> > display log file to see if the display is already running.  Perhaps
> > the crash of the first Xserver is not cleaning up the log file
> > that GDM is using to determine if the Xserver has stopped?  If
> > this is the problem, the GDM code could probably be made more robust.
>
> Thanks,
> Bryce
>
> > > I am writing a FailsafeXServer handler for Ubuntu[1] but am running into
> > > a gdm issue, where gdm keeps spawning X sessions while the failsafe
> > > server is running.
> > >
> > > Here is a test case to recreate the issue:
> > >
> > >  1.  Copy your /etc/X11/xorg.conf to /etc/X11/xorg.conf.failsafe
> > >  2.  Invalidate your /etc/X11/xorg.conf by changing your graphics
> > >      driver to "foobar"
> > >  3.  Copy the script listed below[2] to /etc/gdm/failsafeExample
> > >  4.  In /etc/gdm/gdm.conf set the following:
> > >      FailsafeXServer=/etc/gdm/failsafeExample
> > >  5.  /etc/init.d/gdm restart
> > >
> > > On my system, this the screen blanks 3 times and then shows the
> > > HellowWorld message box properly.  But after a minute or so, the screen
> > > switches to the whiptail error message saying, "There already appears to
> > > be an X server running on display :0. ....."
> > >
> > > I've dug through the source code a bit, but I'm not super familiar with
> > > gdm internals so am not certain what's going on.  I notice in
> > > deal_with_x_crashes() that it sets d->failsafe_xserver = TRUE when it
> > > has a defined failsafe command, and I wonder if perhaps a check for this
> > > simply needs to be added somewhere?
> > >
> > > Advice on this would be most appreciated.
> > >
> > > Thanks,
> > >
> > > Bryce Harrington
> > > bryce canonical com
> > >
> > >
> > > [1]:  https://blueprints.launchpad.net/ubuntu/+spec/bullet-proof-x
> > >
> > > [2]:  /etc/gdm/failsafeExample
> > >
> > > #!/bin/bash
> > >
> > > client="/usr/bin/zenity"
> > > clientargs="--warning --text HelloWorld "
> > > server=/usr/bin/X
> > > serverargs="-br -once -config /etc/X11/xorg.conf.failsafe"
> > > display=:0
> > >
> > > echo "xinit $client $clientargs -- $server $display $serverargs"
> > > xinit $client $clientargs -- $server $display $serverargs
> > > _______________________________________________
> > > gdm-list mailing list
> > > gdm-list gnome org
> > > http://mail.gnome.org/mailman/listinfo/gdm-list
> >
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