Re: how to debug a deadlock'ed kernel?

From: Brian Horton (
Date: Tue Dec 11 2001 - 18:41:05 EST

Thanks, I'll try the nmi_watchdog option out. It appears to not be in
the 2.2.14 kernel, but is in a 2.2.19 kernel that I have from RedHat.

Is there a version of kgdb that works with 2.2.x kernels? I only see 2.4
kernels on the web page (


george anzinger wrote:
> Brian Horton wrote:
> >
> > Anyone got any good tips on how to debug a SMP system that is locked up
> > in a deadlock situation in the kernel? I'm working on a kernel module,
> > and after some number of hours of stress testing, the box locks up. None
> > of the sysrq options show anything on the display, though the reBoot
> > option does reboot the system. RedHat 6.2 and its 2.2.14 kernel. Doesn't
> > hang for me on 2.4, so I need to debug it here...
> >
> > Any hints?
> First read about the NMI boot option in Documentation/nmi_watchdog.txt.
> If you have this turned on and are not oopsing, then the timer (at
> least) is interrupting. The next step I would take would be to used
> either kdb (no experience) or kgdb. I have my own version of this if
> you are interested. It does, however, require an RS232 (serial)
> connection to a host machine.
> I don't know about kdb, but kgdb (my version) uses the NMI to trap the
> other cpus and also traps NMIs on the way to oopsing.
> --
> George
> High-res-timers:
> Real time sched:
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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:22 EST