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Date: Wed, 17 Apr 2013 10:49:24 +0530
From: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
MIME-Version: 1.0
To: Michael Ellerman <michael@ellerman.id.au>
Subject: Re: [PATCH 4/8] Read/Write oops nvram partition via pstore
References: <20130410071835.20150.56489.stgit@aruna-ThinkPad-T420>
 <20130410072303.20150.61382.stgit@aruna-ThinkPad-T420>
 <20130415075555.GE30156@concordia> <516CEDB4.9090005@linux.vnet.ibm.com>
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On Tuesday 16 April 2013 11:50 AM, Aruna Balakrishnaiah wrote:
>
> Currently with this patchset, pstore is not supporting compression of 
> oops-messages
> since it involves some changes in the pstore framework.
>
> big_oops_buf will hold the large part of oops data which will be compressed 
> and put
> to oops_buf.
>
> big_oops_buf: (1.45 of oops_partition_size)

Sorry, big_oops_buf is (2.22 of oops_data_sz)

where oops_data_sz is oops_partition_size - sizeof(oops_log_info).

where oops_log_info is oops header.

> _________________________
> |  header |   oops-text |
> |_________|_____________|
>
> <header> is added by the pstore.
>
> So in case compression fails:
>
> we would need to log the header + last few bytes of big_oops_buf to oops_buf.
> oops_buf: (this is of oops_partition_size)
>

We would need to log the header + last oops_data_sz bytes of big_oops_buf to 
oops_buf.
So that we can have the header while throwing away the data that immediately
follows it.

> we need last few bytes of big_oops_buf as we need to log the recent messages of
> printk buffer. For which we need to know the header size and it involves some
> changes in the pstore framework.
>

Just communicating the header size from pstore would do the job for us.

> I have the compression patches ready, will be posting it soon as a separate set.
>
>> cheers
>>
>