Re: How do I debug kernel panic that occurs while running X?

[Brendon Higgins <blhiggins@gmail.com>]

Hi again,

Charles Krinke wrote (Thu March 1, 2012):
> On the next boot, /var/log/messages shoild contain the last printk's from
> the kernel which would include any panic.

Thanks. I'd already checked there, though, and no dice. The log just skips 
from the last innocuous kernel message to messages about the next boot. 
Nothing about what caused the reboot to be necessary.

Jason Heeris wrote (Fri March 2, 2012):
> I've had problems with write caching causing the last few messages to
> be lost after a panic*, so if you don't see anything suspicious, maybe
> turn off write caching with 'hdparm -W 0 /dev/whatever' for long
> enough to reproduce the crash. Just in case.

Thanks for the tip. I gave that a try using the manual invocation of a kernel 
panic (i.e., echo c > /proc/sysrq-trigger) but I still get nothing in 
/var/log/messages about this event. So, I'm doubtful this'll work when a real 
panic strikes, unfortunately.

FWIW, at the moment I'm running the kernel in testing, but this has been a 
problem since back about 2.6.38 or 39. (I even tried doing a git bisection at 
one point, but being an intermittent problem it's difficult to determine when a 
particular commit doesn't exhibit it - I think I screwed it up at some point.)

Any more ideas? As I said, I tried getting kdump working but have been having 
trouble getting it to behave.

Peace,
Brendon