[nSLUG] kernel debugging?

Peter Cordes peter at llama.nslug.ns.ca
Mon Oct 20 16:18:52 ADT 2003

 I want to track down a race condition in openMosix[1] where processes get
stuck when reading from pipes (ps shows their WCHAN as pipe_wait).  (This is
triggered by dpkg piping from gzip, and by updatedb).  None of the oM
developers have figured it out yet, and most of them don't have access to
SMP systems, so it looks like it would be useful if I could fix it.

 Anyway, there's supposed to be a way to run GDB on the kernel, right?
What tools are there to examine kernel data structures?  The processes are
stuck, so I don't need to single-step the execution, just look at variables
in memory.  I have multiple computers in the cluster I admin at Dal, so
remote-debugging stuff is an option.


[1]www.openmosix.org.  It's a kernel patch for single-system-image
clustering, where the whole cluster can migrate processes between nodes.
It works without requiring any modifications to the programs to be migrated.
It works on x86 Linux, and there was a port to IA64 that isn't doing too
well, and maybe AMD64.

#define X(x,y) x##y
Peter Cordes ;  e-mail: X(peter at cor , des.ca)

"The gods confound the man who first found out how to distinguish the hours!
 Confound him, too, who in this place set up a sundial, to cut and hack
 my day so wretchedly into small pieces!" -- Plautus, 200 BC

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