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

[Eric W. Biederman]

Dharmosoth Seetharam <dseetharam at inbox.com> writes:

>> -----Original Message-----
>> From: ebiederm at xmission.com
>> Sent: Sat, 13 Jun 2009 00:11:25 -0700
>> To: dseetharam at inbox.com
>> Subject: Re: /var/log/messages doesn't have crash info when kernel gets
>> panic/oops/crash
>> 
>> Dharmosoth Seetharam <dseetharam at inbox.com> writes:
>> 
>>> 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?
>> 
> Hi Eric,
>
>> Basic questions.
>> 1) Do you have panic on oops set?
>>    I think that setting more than anything else will be the
>>    difference in what shows up in /var/log/messages.
>
> Yes, in my case panic_on_oops was set with 1

That is the reason thing don't show up in /var/log/messages
because you panic before syslog has a chance to write the messages.

>> 2) Have you tried a dry run and confirmed you can get a crash dump?
>
> No, I haven't tried this.

It sounds like you have not been getting the coredumps when problems
happen.  Running a simple test run to  Alt-sysrq-c to confirm
that things are basically setup ok is a good idea.

>> 3) Are you using kvm
> kvm? kernel virtual memory?

Kernel virtual machine.  In particular.
Hardware acceleration for virtual machines.

Eric