linux-kernel - Re: [RFC PATCH 0/3] Nvram-to-pstore: compression support for oops data

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Message-ID: <51AF8AEA.4030702@linux.vnet.ibm.com>
Date:	Thu, 06 Jun 2013 00:30:58 +0530
From:	Aruna Balakrishnaiah <aruna@...ux.vnet.ibm.com>
To:	linuxppc-dev@...abs.org, paulus@...ba.org,
	linux-kernel@...r.kernel.org, benh@...nel.crashing.org
CC:	jkenisto@...ux.vnet.ibm.com, tony.luck@...el.com,
	mahesh@...ux.vnet.ibm.com, cbouatmailru@...il.com, anton@...ba.org,
	ccross@...roid.com, keescook@...omium.org
Subject: Re: [RFC PATCH 0/3] Nvram-to-pstore: compression support for oops
 data

Hi Ben,

There is no change in this patchset and it applies cleanly on top of
v4 of Nvram-to-pstorepatches.

> The patchset takes care of compressing oops messages while writing to NVRAM,
> so that more oops data can be captured in the given space.
>
> big_oops_buf (2.22 * oops_data_sz) is allocated for compression.
> oops_data_sz is oops header size less of oops partition size.
>
> Pstore will internally call kmsg_dump to capture messages from printk
> buffer. While returning the data to nvram it adds is own header.
>
> For compression:
> 	Register pstore with big_oops_buf.
>
> In case compression fails, copy header added by pstore and
> last oops_data_sz bytes (recent messages) of big_oops_buf to
> nvram for which we need to know header size.
> 	
> patch 01/03 will add a function in pstore to return the header size.
>
> pstore read callback of nvram will read the compressed data and return the
> decompressed data so that dmesg file (under /dev/pstore) is readable.
>
> In case decompression fails, instead of having the compressed data (junk) in the
> dmesg file it will skip and continue reading other partitions. This results in
> absence of dmesg file but will still have files relating to other parititons.
>
>
> ---
>
> Aruna Balakrishnaiah (3):
>        Retreive header size from pstore.
>        powerpc/pseries: Re-organise the oops compression code
>        powerpc/pseries: Support compression of oops text via pstore
>
>
>   arch/powerpc/platforms/pseries/nvram.c |  236 +++++++++++++++++++++++---------
>   fs/pstore/platform.c                   |    7 +
>   include/linux/pstore.h                 |    6 +
>   3 files changed, 182 insertions(+), 67 deletions(-)
>

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