Re: [PATCH 2/8] Add version and timestamp to oops header

[aruna <aruna@linux.vnet.ibm.com>]

On Monday 15 April 2013 01:01 PM, Michael Ellerman wrote:
> On Wed, Apr 10, 2013 at 12:51:12PM +0530, Aruna Balakrishnaiah wrote:
>> Introduce version and timestamp information in the oops header.
>> oops_log_info (oops header) holds version (to distinguish between old
>> and new format oops header), length of the oops text
>> (compressed or uncompressed) and timestamp.
> This needs a much more detailed explanation.
>
> I think what you're doing is you're overlaying the new information so
> that the version field in oops_log_info sits in the same location as the
> length field in the old format. And then you're defining the version to
> be a value that is an illegal length.

Thats right.

> So existing tools will refuse to dump new style partitions,
> because they'll think the length is too large. You've tested that?

Yeah, I have tested that.

>
> Updated tools will know about both formats, so will be able to handle
> either old or new style partitions.
>
> Is that correct?

Yeah, thats correct.

>
> And we're adding the timestamp just because we can and it'd be nice to
> have?

Thats right. And also, the main reason behind adding timestamp is
it will be used when we create a pstore file for oops messages.
The pstore file's timestamp will reflect the timestamp in the oops-header
added during the crash.

> cheers
>