Validating Display Management with GDM

From Sun Ray User Group Wiki

Sanity Checking Display Management on GDM-based systems

Unlike dtlogin, which uses a simple, readable file format for maintaining the state of which displays are being managed (which has its own set of issues around atomicity of updates) GDM maintains that state in runtime datastructures that are not directly readable and may in fact be distributed among different processes (this is particularly true starting with GDM 2.24 which shares state between ConsoleKit and GDM). Since accessing that data has overhead and is different from the method used by dtlogin, and since SRSS manages some displays directly (e.g. loginGUI-based authentication sessions) SRSS maintains parallel state in exactly the same manner as is used for dtlogin.

Sometimes due to a bug managed display state has been known to become skewed.

I've written a little tool to help verify that state is consistent. It can be fooled into "false negatives" when state is changing quickly, so it should not be relied upon unless multiple executions indicates a persistent problem. The tool is called 'isGdmSyncedWithSRSS'.

Downloads

• OpenSolaris Download. Although this version relies on ksh93 and thus works only on OpenSolaris, it's the version I'm most likely to maintain since I am not a perl expert, sorry.
  Use browser "Save As" feature, remove the .sh suffix, save as filename isGdmSyncedWithSRSS

• Linux Download. A translation of Bob's script to Perl, adopted for Linux, tested with Debian.