kexec/ kdump setup problem

[Neil Horman]

On Tue, Apr 29, 2008 at 07:14:36PM -0700, Mrunal Gawade wrote:
> Hi,
> 
> I just checked /sys/kernel/kexec_crash_loaded file after giving the kexec -p
> command for loading panic kernel. And the value was 1. So it was loaded
> successfully. I then crashed kernel and it hanged. I rebooted manually and
> checked the value in the file again and it was "0". So across reboot it got
> reset. So if I assume that the kernel loading was successful, the question
> remains if it got loaded successfully at the designated space 65M at 16M. How
> do I know that? I am running SUSE 2.6.25 on a VMWare workstation. Does
> running on VM could change any thing such as memory layout or anything
> related to panic handling?
> 

As Sachin mentioned, kexec_crash_loaded gets reset accross reboots.

As for use on a VMWare guest, its behavior is anyones guess.  Best thing I could
think to do would be to add earlyprintk to the kdump kernel command line, and
watch the serial console for mesages about where you're hanging (see
Documentations/kernel-parameters.txt for details about earlyprintk).

Neil

> You specified taking a look at the /sys/kernel/kexec_crash_loaded file. Is
> there a central document which documents all these error resolving
> guidelines? Also I checked in the /var/log/messages and there is no message
> related to this printed over there.
> 
> 
> Thank you,
> Mrunal
> 
> On Tue, Apr 29, 2008 at 5:17 PM, Neil Horman <nhorman at redhat.com> wrote:
> 
> > On Tue, Apr 29, 2008 at 03:40:13PM -0700, Mrunal Gawade wrote:
> > > Thanks Sachin.
> > >
> > > The value over there is a "0" which means I have a failure. How do I
> > > diagnose what is the problem? I was able to load a normal kernel and
> > then
> > > use "e" option to reboot into it. But crash dump kernel seemed to be
> > giving
> > > problem always.
> > >
> > >
> > > Thank you,
> > > Mrunal
> > >
> >
> > check /var/log/messages, to see if there is any message there.  It
> > wouldn't hurt
> > to enable debugging in the kexec binary either, although if the load is
> > actually
> > failing, I would think you would get something on stderr.  First guess
> > would be
> > that you don't have a crashkernel area specified on your command line (or
> > you
> > do, and its reservation failed, which also will show up in the logs most
> > likely)
> >
> > Neil
> >
> > > On Tue, Apr 29, 2008 at 4:13 AM, Sachin P. Sant <sachinp at in.ibm.com>
> > wrote:
> > >
> > > > Mrunal Gawade wrote:
> > > >
> > > > > After I execute this command. Should I expect any prompt that kernel
> > > > > loaded successfully?
> > > > >
> > > > Check the /sys/kernel/kexec_crash_loaded file. Value "1" means
> > success.
> > > >
> > > > Thanks
> > > > -Sachin
> > > >
> > > >
> >
> > > _______________________________________________
> > > kexec mailing list
> > > kexec at lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/kexec
> >
> >
> > --
> > /***************************************************
> >  *Neil Horman
> >  *Software Engineer
> >  *Red Hat, Inc.
> >  *nhorman at redhat.com
> >  *gpg keyid: 1024D / 0x92A74FA1
> >  *http://pgp.mit.edu
> >  ***************************************************/
> >

-- 
/***************************************************
 *Neil Horman
 *Software Engineer
 *Red Hat, Inc.
 *nhorman at redhat.com
 *gpg keyid: 1024D / 0x92A74FA1
 *http://pgp.mit.edu
 ***************************************************/