[Bug 35949] gdm hangs with any kernel newer than a 2.6.15-14-686

[skwashd]

Public bug reported:
https://launchpad.net/malone/bugs/35949

Affects: gdm (Ubuntu)
       Severity: Normal
       Priority: (none set)
         Status: Unconfirmed

Description:
When trying to use any official dapper kernel newer than 2.6.15-14-686
gdm hangs.  Here is the process:

1 machine happily boots
2 I watch the nice animations
3 screen goes black with the cursor flashing once or twice in the top left corner of the screen
4 cursor stays solid for 1 or 2 seconds
5 screen goes completely black
6 hdd light flickers a little bit
7 machine sits there doing bugger all
8 try ctrl-alt-f[1-6] nothing
9 try ctrl-alt-bs nothing
10 scream about how fscking annoying this is
11 remember alt-sysreq-b and try it
12 machine reboots

When trying a 2.6.16-rc6 self compiled kernel the box has locked hard
and even steps 11 & 12 don't work, even with repeated use of step 10.
The power button is the only solution here.

This is what I expect to happen, and happens with 2.6.15-14-686:
1 machine happily boots
2 I watch the nice animations
3 screen goes black with the cursor flashing once or twice in the top left corner of the screen
4 cursor stays solid for 1 or 2 seconds
5 screen goes completely black
6 hdd light flickers a little bit
7 the little circle animation comes up
8 the gdm graphical greeter loads
9 I enter my username and press enter
10 I enter my password and press enter
11 I admire the attractiveness of my wallpaper while gnome fires up

I have been trying to find out how I get gdm to output a stack of debug
info into a log file, but google, man or irc don't seem to have the
answer.

Here is some basic system info:

Dell Latitude D810
Pentium M 1.86GHz
ATI Radeon Mobility X600 (using xorg "ati" driver)

here is a gdm log of when it works
X Window System Version 7.0.0
Release Date: 21 December 2005
X Protocol Version 11, Revision 0, Release 7.0
Build Operating System:Linux 2.6.12 i686
Current Operating System: Linux woby 2.6.15-14-686 #1 SMP PREEMPT Wed Jan 25 16:05:50 UTC 2006 i686
Build Date: 16 March 2006
        Before reporting problems, check http://wiki.x.org
        to make sure that you have the latest version.
Module Loader present
Markers: (--) probed, (**) from config file, (==) default setting,
        (++) from command line, (!!) notice, (II) informational,
        (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Wed Mar 22 13:50:03 2006
(==) Using config file: "/etc/X11/xorg.conf"
(EE) end of block range 0x5200ffff < begin 0xdf300000
(EE) RADEON(0): Failed to parse MetaModes or no modes found. MergeFB mode disabled.
(EE) RADEON(0): [dri] DRIScreenInit failed.  Disabling DRI.
error opening security policy file /etc/xserver/SecurityPolicy
Could not init font path element unix/:7100, removing from list!


and when it fails:
X Window System Version 7.0.0
Release Date: 21 December 2005
X Protocol Version 11, Revision 0, Release 7.0
Build Operating System:Linux 2.6.12 i686
Current Operating System: Linux woby 2.6.15-19-686 #1 SMP PREEMPT Mon Mar 20 17:33:20 UTC 2006 i686
Build Date: 16 March 2006
        Before reporting problems, check http://wiki.x.org
        to make sure that you have the latest version.
Module Loader present
Markers: (--) probed, (**) from config file, (==) default setting,
        (++) from command line, (!!) notice, (II) informational,
        (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Wed Mar 22 13:47:42 2006
(==) Using config file: "/etc/X11/xorg.conf"
(EE) end of block range 0x5200ffff < begin 0xdf300000
(EE) RADEON(0): Failed to parse MetaModes or no modes found. MergeFB mode disabled.
error opening security policy file /etc/xserver/SecurityPolicy
Could not init font path element unix/:7100, removing from list!

If you need more info let me know.