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acg mode causing reboots?

To: kernprof@xxxxxxxxxxx
Subject: acg mode causing reboots?
From: Jeremy Elson <jelson@xxxxxxx>
Date: Sat, 03 Mar 2001 00:22:49 -0800
Cc: jelson@xxxxxxx
Sender: owner-kernprof@xxxxxxxxxxx
Hi,

First off I'd like to thank you for kernprof specifically, and for all
your Linux support & enthusiasm general, and even more generally for
just being a cool company for many years.

I'm having a problem with the 2.4.1 kernel patch of kernprof.  It
seems that sometimes, when I start collecting profiling samples in
ACG-mode (i.e., kernprof -t acg, then kernprof -b), the machine will
reboot within 10 seconds.  This doesn't happen until I activate
profiling: the machine runs fine with profiling support in the kernel
but not active.  And the machine seems to run find when kernprof is
active in PC mode.  One time, I did successfully collect ACG samples,
but many other times I get these reboots instead.

Some additional background:

a) I am using the latest prerelease of GCC/EGCS  (gcc version 2.95.3
20010219 (prerelease)), plus your one-line patch.

b) I am using kernel 2.4.1 + kernprof patch 0.8 for 2.4.1

c) I am using kernprof userland utils v1.1

d) all 3 options for profiling are on in the kernel (frame ptrs,
profiling support [not a module], and the char device)


The first time I tried kernprof, the machine rebooted when collecting
acg samples.  I then went into /usr/src/linux, saved my .config, did
"make mrproper", and tried again - and everything started working!  I
successfully collected call-graph data and viewed it with 'gprof'.  I
thought that perhaps there had been some old object files left around
the first time, or an old makefile that was still omitting the frame
pointer.

Then, I added my new device driver to the kernel (the driver is very
stable, but doesn't perform as well as I need - hence kernprof),
recompiled.  Once again the reboots started: I'd type "kernprof
-b", and within 10 seconds I get a reset.  I tried the make mrproper
trick again but the reboots are still happening.

Any ideas?

Regards,
Jeremy


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