Problem with the xorg ati driver and kexec/kdump

[TuskenTower]

All,
I am not sure how to present the information I have, so please bear
with me.  I am also dealing with distribution released Xorg and not
plain Xorg.  I am unfamiliar with the Xorg code and building Xorg.

My problem is this:
I am testing the a RHEL 5 beta release with kexec
(http://lwn.net/Articles/15468/) and kdump
(http://lwn.net/Articles/108595/).  When I use kexec/kdump from the
GUI (Xorg running with the ati driver), the subsequent kernel crashes
hard (no panic, nothing at all) and I have not been able to determine
what is causing it.

Here's the fun part, if I kexec/kdump from a VT or from a VESA GUI
(Xorg + vesa driver) the machine will not crash.  If I use the serial
line for the console without the video console in the subsequent
kernel, it will not crash.

>From what I have observed, the ati driver is doing something that the
ES7000 platform does not handle very well.  I have just starting to
read the changelogs based on the 6.9 release date.   I have done a
diff of the source trees and assumed that the only code I need to look
at is related to Mach64 and Mach64 initialization (is this assumption
wrong?).

>From reading the code, I can only see changes related to EXA and XAA,
but I have no idea what those mean.  The code changes look fairly
contained, but I was hoping someone might know what could cause
problems (I think I saw an APIC error reported somewhere).

I have not compiled the Xorg ati driver yet to drop in some printks.
If any of you have any suggestions (no I have not searched for Xorg
driver debugging tips yet), please let me know.  Or at the very least
punt (http://members.tripod.com/~tammy_lynn/gar940-1.gif) me in the
right direction.

thanks,
Amul

Configuration:
SuSE Linux Enterprise Server 10
Xorg ati driver source seems to map directly to X11R6.9.0 (with some
differences in Radeon code)
Arch: x86_64
Xorg.0.log:
  X Window System Version 6.9.0
  Release Date: 21 December 2005
  X Protocol Version 11, Revision 0, Release 6.9
  Build Operating System: SuSE Linux [ELF] SuSE

RedHat Enterprise Linux 5 (beta)
Xorg ati driver source of the Xserver seems to match Xorg 7.2 release
of the ati driver X11R7.2-6.6.3 (with some differences in the Radeon
code)
Arch: x86_64
Xorg.0.log:
  X Window System Version 7.1.1
  Release Date: 12 May 2006
  X Protocol Version 11, Revision 0, Release 7.1.1
  Build Operating System: Linux 2.6.9-34.ELsmp x86_64 Red Hat, Inc.

Hardware:
Unisys ES7000, any configuration from 4 to 32 processors (dual-core
and/or hyper threading) with 64GB to 256GB RAM.  Using a Rage Mobility
chipset, lspci output
01:01.0 VGA compatible controller: ATI Technologies Inc Rage Mobility
P/M (rev 64)
This card is sitting behind an Intel ICH4 bridge.
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 82)