/var/log/messages doesn't have crash info when kernel gets panic/oops/crash

[Neil Horman]

On Fri, Jun 12, 2009 at 11:01:35PM -0800, Dharmosoth Seetharam wrote:
> 
> Hi Neil,
> 
> Thanks for your quick reply.
> 
> What you have suggested is nice when we got/save crash dump (i.e vmcore)
> What if we failed to save/capture vmcore info or vmcore is corrupted etc. then we dont get any information
> regarding the panic/crash/oops at anywhere?
> 
If the vmcore is corrupted to the point where makedumpfile can't extract the
dmesg log, then its certain that syslog wouldn't have been able to write
anything to /var/log/messages either.  As a last resort you can try run strings
on the corrupted vmcore and see if the dmesg log is still in there somewhere.

If you forgot to capture the vmcore, theres not much more help I can give you,
Im afraid.  You'll just have to make sure you capture it next time.  If you only
need the backtrace, and don't want the rest of the vmcore, you can make kdump
just run makedumpfile --dump-dmesg /proc/vmcore /var/log/oops.txt

Neil

>  
> 
> 
> Thanks and Regards
> 
>  Seetharam
> 
> 
> > -----Original Message-----
> > From: nhorman at redhat.com
> > Sent: Fri, 12 Jun 2009 16:05:13 -0400
> > To: dseetharam at inbox.com
> > Subject: Re: /var/log/messages doesn't have crash info when kernel gets
> > panic/oops/crash
> > 
> > On Fri, Jun 12, 2009 at 01:25:49AM -0800, Dharmosoth Seetharam wrote:
> >> Hi,
> >> 
> >> I have encounter a problem called /var/log/messages does not contain any
> >> information
> >> on kernel crash dump.
> >> 
> >> Prior to enabling KEXEC we saw stack traces and bug info etc in
> >> /var/log/messages.
> >> After enabling KEXEC feature those info was missed.
> >> 
> >> How can we get those missed info in /var/log/messages even when KEXEC
> >> feature is enabled.
> >> 
> >> Any help will appreciate.
> >> 
> > run crash on the resultant vmcore file that kexec can produce/save and
> > get the
> > dmesg log out of it.
> > alternatively you can use makedumpfile with the --dump-dmesg log
> > 
> > Neil
> > 
> >> 
> >> Thanks and Regards
> >> Seetharam
> >> 
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