From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp06.au.ibm.com (e23smtp06.au.ibm.com [202.81.31.148]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp06.au.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 42AF12C0090 for ; Thu, 27 Jun 2013 19:42:30 +1000 (EST) Received: from /spool/local by e23smtp06.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 27 Jun 2013 19:35:11 +1000 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [9.190.235.21]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 707152BB0051 for ; Thu, 27 Jun 2013 19:42:25 +1000 (EST) Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r5R9gGjk54329574 for ; Thu, 27 Jun 2013 19:42:16 +1000 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r5R9gNVC031780 for ; Thu, 27 Jun 2013 19:42:25 +1000 Message-ID: <51CC08FC.6000301@linux.vnet.ibm.com> Date: Thu, 27 Jun 2013 15:12:20 +0530 From: Aruna Balakrishnaiah MIME-Version: 1.0 To: "Luck, Tony" Subject: Re: [PATCH 3/3] powerpc/pseries: Support compression of oops text via pstore References: <20130624061936.12963.72529.stgit@aruna-ThinkPad-T420> <20130624062316.12963.87911.stgit@aruna-ThinkPad-T420> <51C94101.3030702@linux.vnet.ibm.com> <3908561D78D1C84285E8C5FCA982C28F31C5376F@ORSMSX106.amr.corp.intel.com> In-Reply-To: <3908561D78D1C84285E8C5FCA982C28F31C5376F@ORSMSX106.amr.corp.intel.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: "jkenisto@linux.vnet.ibm.com" , Kees Cook , "mahesh@linux.vnet.ibm.com" , Colin Cross , LKML , "linuxppc-dev@ozlabs.org" , "paulus@samba.org" , Anton Blanchard , Anton Vorontsov List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Tony, On Tuesday 25 June 2013 09:32 PM, Luck, Tony wrote: >> Introducing headersize in pstore_write() API would need changes at >> multiple places whereits being called. The idea is to move the >> compression support to pstore infrastructure so that other platforms >> could also make use of it. > Any thoughts on the back/forward compatibility as we switch to compressed > pstore data? E.g. imagine I have a system installed with some Linux distribution > with a kernel too old to know about compressed pstore. I use that machine to > run the latest kernels that do compression ... and one fine day one of them crashes > hard - logging in compressed form to pstore. Now I boot my distro kernel to pick > up the pieces ... what do I see in /sys/fs/pstore/*? Some compressed files? Can I > read them with some tool? > > This somewhat of a corner case - but not completely unrealistic ... I'd at least > like to be reassured that the old kernel won't choke when it sees the compressed > blobs. openssl command line tool can be used to decompress the compressed data of the pstore file in the above scenario. Usage: cat | openssl zlib -d > -Tony >