Re: problems debugging panic with gdb, kdump, and vmcore

From: Robert Hancock
Date: Tue Jul 21 2009 - 12:50:20 EST


On 07/20/2009 10:46 PM, Steven Noonan wrote:
Hi folks,

I've got a kernel panic that is easily reproducible (I am 99% sure
that 2.6.30.2 itself isn't to blame, it's the out-of-tree drm module I
built from here: http://cgit.freedesktop.org/mesa/drm/). I could just
follow the stack trace, but I'd like to learn how to use kexec/kdump
to debug this. So far, I've got kexec successfully loading a kernel on
a panic, and I'm able to copy the vmcore out of /proc to someplace
permanent, but trying to use gdb on it gives very strange results. I
don't know what I'm doing wrong. I've rebuilt the kernel multiple
times and ensured that ccache is cleared each time just in case that
might interfere. Here's what I'm getting with gdb:


Alcarin linux # pwd
/usr/src/linux
Alcarin linux # gdb vmlinux /var/tmp/vmcore
GNU gdb 6.8
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-pc-linux-gnu"...

warning: exec file is newer than core file.

Why is the vmlinux file newer than the vmcore file?

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