Re: Coredumps and 'crash' utility...

From: Dave Anderson <anderson@redhat.com>
To: xen-devel@lists.xensource.com
Subject: Re: Coredumps and 'crash' utility...
Date: Thu, 04 Oct 2007 08:59:50 -0400	[thread overview]
Message-ID: <4704E3C6.1020807@redhat.com> (raw)
In-Reply-To: <E1IdFjS-0001vx-KP@host-192-168-0-1-bcn-london>

> I'm using XenSource 4.0 and have the need to debug the
> XenSource-provided hypervisor's coredump file produce at /proc/vmcore.
> I tried using Anderson's "crash" utility to read that file but I'm
> getting the following error:
> 
> crash ./vmlinuz /dom0/proc/vmcore
> 
> crash 4.0-4.7
> Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007  Red Hat, Inc.
> Copyright (C) 2004, 2005, 2006  IBM Corporation
> Copyright (C) 1999-2006  Hewlett-Packard Co
> Copyright (C) 2005, 2006  Fujitsu Limited
> Copyright (C) 2006, 2007  VA Linux Systems Japan K.K.
> Copyright (C) 2005  NEC Corporation
> Copyright (C) 1999, 2002, 2007  Silicon Graphics, Inc.
> Copyright (C) 1999, 2000, 2001, 2002  Mission Critical Linux, Inc.
> This program is free software, covered by the GNU General Public
> License,
> and you are welcome to change it and/or distribute copies of it under
> certain conditions.  Enter "help copying" to see the conditions.
> This program has absolutely no warranty.  Enter "help warranty" for
> details.
> 
> crash: /dom0/proc/vmcore: not a supported file format
> 
> 
> I examined the core file and this is what it says its type is.
> 
> #file /dom0/proc/vmcore
> /dom0/proc/vmcore: ELF 64-bit LSB core file AMD x86-64, version 1
> (SYSV), SVR4-style
> 
> 
> 1) Has anyone been able to use 'crash' with XenSource's kernels?
> 2) What is the right vmcore file format for an open-source Xen?  Can
> someone show me the output of 'file' on their vmcore so I can compare?

First, you won't get anywhere with the vmlinuz file; you must
use the kernel's vmlinux file, which must have been built with -g.

I don't test current XenSource kernels, but I don't know of any
recent changes from the Red Hat version that would break things.

A "readelf -a vmcore" would be more useful than a file output.
And what is the host machine that you are attempting the crash
session on?  One reason for the "not a supported file format"
would be if you attempt to run an x86 crash executable with
an x86_64 vmlinux/vmcore or vice-versa.

Also, it will probably be more useful to join and take this
up on the crash-utility mailing list:

  https://www.redhat.com/mailman/listinfo/crash-utility

Dave Anderson