From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754392AbZHaD3V (ORCPT ); Sun, 30 Aug 2009 23:29:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754370AbZHaD3U (ORCPT ); Sun, 30 Aug 2009 23:29:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:28688 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754362AbZHaD3U (ORCPT ); Sun, 30 Aug 2009 23:29:20 -0400 Message-ID: <4A9B430B.5060006@redhat.com> Date: Mon, 31 Aug 2009 11:27:07 +0800 From: Amerigo Wang User-Agent: Thunderbird 2.0.0.22 (X11/20090719) MIME-Version: 1.0 To: michael@ellerman.id.au CC: linux-kernel@vger.kernel.org, tony.luck@intel.com, linux-ia64@vger.kernel.org, Neil Horman , "Eric W. Biederman" , kamezawa.hiroyu@jp.fujitsu.com, Andi Kleen , "M. Mohan Kumar" , akpm@linux-foundation.org, bernhard.walle@gmx.de, Fenghua Yu , Ingo Molnar , Anton Vorontsov Subject: Re: [Patch 0/8] V5 Implement crashkernel=auto References: <20090827031800.4534.94868.sendpatchset@localhost.localdomain> <1251680096.5279.6.camel@concordia> In-Reply-To: <1251680096.5279.6.camel@concordia> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Michael Ellerman wrote: > On Wed, 2009-08-26 at 23:15 -0400, Amerigo Wang wrote: > >> V4 -> V5: >> - Rename the global functions, as suggested by Andrew. >> - Save some macros, as suggested by Andrew. >> - Change the high threshold, from 32G to 4G. >> - Change the low threshold on ppc, suggested by ppc developers. >> - Make the mm part as a seperate function, suggest by Eric. >> - Make the IA64 code more readable. >> - Reorder the patchset again, since review from mm people is done. >> >> V3 -> V4: >> - Reorder the patches. >> - Really free the reserved memory, instead of remapping it. >> (Thanks to KAMEZAWA Hiroyuki!) >> - Release the reserved memory resource when the size is 0. >> - Use strict_strtoul() instead of simple_strtoul(). >> >> V2 -> V3: >> - Use more clever way to calculate reserved memory size, especially for IA64. >> - Add that patch that implements shrinking reserved memory >> >> V1 -> V2: >> - Use include/asm-generic/kexec.h, suggested by Neil. >> - Rename a local variable, suggested by Fenghua. >> - Fix some style problems found by checkpatch.pl. >> - Unify the Kconfig docs. >> >> This series of patch implements automatically reserved memory for crashkernel, >> by introducing a new boot option "crashkernel=auto". This idea is from Neil. >> >> In case of breaking user-space applications, it modifies this boot option after >> it decides how much memory should be reserved. >> >> On different arch, the threshold and reserved memory size is different. Please >> refer patch 7/8 which contains an update for the documentation. >> >> Patch 8/8 implements shrinking reserved memory at run-time, which is useful >> when more than enough memory is reserved automatically. >> >> This patchset _is_ already tested on x86_64, IA64 and ppc64. >> > > I don't want to sound like a micro-kernel zealot, I'm not, but I'm still > unconvinced as to why the auto logic needs to go in the kernel. What is > the compelling reason that the kernel needs to do this calculation vs > some userspace tool? We already have the syntax that allows defining a > different crash size depending on the size of RAM. > Take a look at the x86 part, it can not be done _directly_ in kernel command line with the syntax.