Re: [Crash-utility] How do debug the kdump kernel using a Xen dump-core file?
Hi Olaf,
On Thu, Feb 10, 2011 at 02:07:02PM +0100, Olaf Hering wrote:
Hello,
'xm dump-core -L <domain>' generates a coredump of a Xen4 HVM guest, and
crash is able to poke around in this coredump.
Thanks for that.
But: How can I use crash to debug the crash/kdump kernel itself?
I did a 'echo c > /proc/sysrq-trigger' and want to look at the crash
kernel, not the normal kernel.
Olaf
You can make the crash kernel come all the way up to multi-user mode.
Then run crash. I haven't run crash under the crash kernel, but I don't
see why it wouldn't work.
I use this method with a SLES system:
edit /etc/sysconfig/kdump and set KDUMP_SAVEDIR to a
non-existing dir:
KDUMP_SAVEDIR="file:///fubar"
KDUMP_IMMEDIATE_REBOOT="no"
Or this seems to work with a RHEL6 system:
- edit /etc/init.d/kdump and comment out the makedumpfile and restart
lines; just make it exit
- modify script /sbin/mkdumprd so that it does not save a
dump, but goes to user mode:
2429,2430c2429,2432
< emit " $CORE_COLLECTOR /proc/vmcore \$VMCORE-incomplete...
emit "# $CORE_COLLECTOR /proc/vmcore
\$VMCORE-incomplete...
---
< emit " exitcode=\$?"
emit " exitcode=1"
2444c2446,2448
< emit " $FINAL_ACTION"
emit " echo bye"
and
/etc/init.d/kdump to not call save_core in the crash kernel:
start)
if [ -s /proc/vmcoreXXX ]; then
save_core
)
-Cliff
--
Cliff Wickman
SGI
cpw(a)sgi.com
(651) 683-3824