This section discusses helpful tips for getting GDM working. In general, if you have a problem using GDM, you can submit a bug to the "gdm" category in bugzilla.gnome.org or send an email to the
mail list.
If GDM is failing to work properly, it is always a good idea to include
debug information. Use the gdmsetup command to turn
on debug ("Enable debug messages to system log" checkbox in the
"Security" tab), then use GDM to the point where it fails, and
include the GDM output sent to your system log
(<var>/log/messages
or
<var>/adm/messages
depending on your operating
system). Since the system log can be large, please only include the GDM
debug information and do not sent the entire file. If you do not see any
GDM syslog output, you may need to configure syslog (see syslog.3c man
page).
You should not leave debug on after collecting data. It will clutter your syslog and slow system performance.
There are a many problems that can cause GDM to fail to start, but this section will discuss a few common problems and how to approach tracking down a problem with GDM starting. Some problems will cause GDM to respond with an error message or dialog when it tries to start, but it can be difficult to track down problems when GDM fails silently.
First make sure that the X server is configured properly. The GDM configuration file contains a command in the [server-Standard] section that is used for starting the X server. Verify that this command works on your system. Running this command from the console should start the X server. If it fails, then the problem is likely with your X server configuration. Refer to your X server error log for an idea of what the problem may be. The problem may also be that your X server requires different command-line options. If so, then modify the X server command in the GDM configuration file so that it is correct for your system.
Another common problem is that the GDM greeter program is having trouble starting. This can happen, for example, if GDM cannot find a needed library or other resource. Try starting the X server and a terminal program, set the shell environment variable DOING_GDM_DEVELOPMENT=1 and run <lib>/gdmlogin or <lib>/gdmgreeter. Any error messages echoed to the terminal will likely highlight the problem. Also, turning on debug and checking the output sent to the system log will often highlight the problem.
Also make sure that the /tmp
directory has
reasonable ownership and permissions, and that the machine's file
system is not full. These problems will cause GDM to fail to start.
GDM saves user settings, such as your default session and default
language, in the ~/.dmrc
. Other files, such
as the user's ~/.Xauthority
file will also
affect login. GDM, by default, is strict about how it tries to
access files in the user's home directory, and will ignore the file if
they do not conform to certain rules. You can use the
RelaxPermissions
configuration option to
make GDM less strict about how it accesses files in the user's
home directory, or correct the permissions issues that cause GDM
to ignore the file. This is discussed in detail described in the
"File Access" section of the "Overview".