Re: debugging an oops that kills the system

From: Roland Dreier
Date: Tue Oct 21 2008 - 14:39:39 EST

> I'm hoping for some pointers on debugging an oops that ultimately
> hangs the system. I'm doing some scheduler work and I can fairly
> reliably duplicate the error on my machine, but the output is too
> large for one screen and the system becomes unresponsive after the
> crash so I can't scroll the console. I tried purchasing a USB->DB9
> cable to log to a remote terminal, but so far I haven't had any luck
> getting that to work. Using kdump/kexec doesn't work either--I got
> the second kernel to boot successfully using the magic sysrq example
> in the documentation, but the second kernel doesn't boot with my
> actual crash. Any other suggestions for what I might do?

If you have two machines (it sounds like you do) and serial console is
not working for you (could be a setup problem -- do you have a
"console=" line on your kernel command line?), then netconsole might be
a good way to debug: Documentation/networking/netconsole.txt

- R.
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