Hello,

I have this issue with compressed RHEL5 vmcore files, I can't get it to loaded to the crash utility. I don't have this problem with RHEL4 vmcores (diskdump).
The debuginfo kernel exactly matches the kernel version that generated the vmcore

[root@test-fc12 ~]# crash  usr/lib/debug/lib/modules/2.6.18-92.1.10.el5debug/vmlinux /nas01/cores/2.6.18-92.1.10.el5.vmcore

crash 4.0.9-2.fc12
Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009  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.
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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.

GNU gdb 6.1
Copyright 2004 Free Software Foundation, Inc.
GDB 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.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu"...

crash: page excluded: kernel virtual address: ffffffff804f1260  type: "possible"
WARNING: cannot read cpu_possible_map
crash: usr/lib/debug/lib/modules/2.6.18-92.1.10.el5debug/vmlinux and /nas01/cores/2.6.18-92.1.10.el5.vmcore do not match!

Usage:
 crash [-h [opt]][-v][-s][-i file][-d num] [-S] [mapfile] [namelist] [dumpfile]

Enter "crash -h" for details.

[root@test-fc12 ~]# strings usr/lib/debug/lib/modules/2.6.18-92.1.10.el5debug/vmlinux | grep 2.6 | head -2
Linux version 2.6.18-92.1.10.el5debug (brewbuilder@ls20-bc2-13.build.redhat.com) (gcc version 4.1.2 20071124 (Red Hat 4.1.2-42)) #1 SMP Wed Jul 23 04:27:38 EDT 2008
2.6.18-92.1.10.el5debug SMP mod_unload gcc-4.1

running strings on the rhel5 vmcore file:

[root@test-fc12 cores]# strings 2.6.18-92.1.10.el5.vmcore | grep 2.6 | head -2
2X6
2T6(

does makedumpconfig's compression have something to do with this? from kdump.conf on the machine where i got that vmcore:

...
core_collector makedumpfile -c -d31
...

Thank you in advace!

Regards,
Marc