From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030401Ab2CNCTP (ORCPT ); Tue, 13 Mar 2012 22:19:15 -0400 Received: from fifo99.com ([67.223.236.141]:56979 "EHLO fifo99.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965159Ab2CNCTN (ORCPT ); Tue, 13 Mar 2012 22:19:13 -0400 Date: Tue, 13 Mar 2012 19:19:06 -0700 From: Daniel Walker To: Andrew Morton Cc: Avery Pennarun , Josh Triplett , "Paul E. McKenney" , Ingo Molnar , "David S. Miller" , Peter Zijlstra , "Fabio M. Di Nitto" , Johannes Weiner , Olaf Hering , Paul Gortmaker , Tejun Heo , "H. Peter Anvin" , Yinghai LU , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Seiji Aguchi Subject: Re: [PATCH 0/5] Persist printk buffer across reboots. Message-ID: <20120314021906.GC5218@fifo99.com> References: <1331617001-20906-1-git-send-email-apenwarr@gmail.com> <20120313170851.GA5218@fifo99.com> <20120313151049.fa33d232.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120313151049.fa33d232.akpm@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 13, 2012 at 03:10:49PM -0700, Andrew Morton wrote: > On Tue, 13 Mar 2012 10:08:51 -0700 > Daniel Walker wrote: > > > On Tue, Mar 13, 2012 at 01:36:36AM -0400, Avery Pennarun wrote: > > > The last patch in this series implements a new CONFIG_PRINTK_PERSIST option > > > that, when enabled, puts the printk buffer in a well-defined memory location > > > so that we can keep appending to it after a reboot. The upshot is that, > > > even after a kernel panic or non-panic hard lockup, on the next boot > > > userspace will be able to grab the kernel messages leading up to it. It > > > could then upload the messages to a server (for example) to keep crash > > > statistics. > > > > There's currently driver/mtd/mtdoops.c, fs/pstore/, and > > drivers/staging/android/ram_console.c that do similar things > > as this. Did you investigate those for potentially modifying them to add > > this functionality ? If so what issues did you find? > > > > I have a arm MSM G1 with persistent memory at 0x16d00000 size 20000bytes.. > > It's fairly simple you just have to ioremap the memory, but then it's good > > for writing.. Currently the android ram_console uses this. How would I > > convert this area for use with your changes? > > Yes, and various local implementations which do things such as stuffing > the log buffer into NVRAM as the kernel is crashing. > > I do think we'd need some back-end driver arrangement which will permit > the use of stores which aren't in addressible mamory. > > It's quite the can of worms, but definitely worth doing if we can get > it approximately correct. For sure.. I've had at least a couple non-OOPS based crashed I would have liked to get logs for. There is also this series, http://lists.infradead.org/pipermail/kexec/2011-July/005258.html It seems awkward that pstore is in fs/pstore/ then pstore ends up as the "back end" where it could just be the whole solution. Daniel