Freezes on XPRESS 200M - how to debug?

[Jerome Glisse]

On Tue, May 04, 2010 at 10:25:04PM +0200, Daniel Klaffenbach wrote:
> Hi,
> 
> I am on a HP laptop (nx6125) with an rs480 chipset. Unfortunately I experience 
> many hard freezes resulting in system lockups[*] when DRM and/or KMS are 
> enabled.
> 
> I would like to debug this issue to provide some helpful information but 
> unfortunately the system (not just X) always freezes completely. I am not even 
> able to use an active SSH session to watch the system log files - as soon as 
> the problem occurs the system does not respond to anything anymore.
> In fact, it seems the system does not even get to the point of logging a crash 
> because it is already frozen at that point.
> 
> Is there anyone who could point out how to get useful error messages or even 
> backtraces in such a case?
> 
> 
> - Dan

Even us (developer) don't have a process to debug lockup. Most of the
time is about testing thing in the kernel hoping it helps. So it's
random change, test & cross finger.

This is why hard lockup are hard to fix.

Cheers,
Jerome