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

[Dharmosoth Seetharam]

> -----Original Message-----
> From: ebiederm at xmission.com
> Sent: Sat, 13 Jun 2009 05:51:25 -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:
> 
>>> -----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.

Thanks.
So, if panic_on_oops set with 0(default), we will get all the 
needed info like stack traces, bug info etc. in /var/log/messages then reboots.

Or do we need to apply any specific patches to get info in /var/log/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.
> 
Sorry, I misunderstood your question.
I have gave dry run and confirmed that the dumps are getting saved in particular dir and able to analyze.

I did in both the ways like
1 - echo c > /proc/sysrq-trigger
2 -Alt -sysrq -c



thanks,
Seetharam

>>> 3) Are you using kvm
>> kvm? kernel virtual memory?
> 
> Kernel virtual machine.  In particular.
> Hardware acceleration for virtual machines.
> 
> Eric

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