From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755432AbZHLBv5 (ORCPT ); Tue, 11 Aug 2009 21:51:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755098AbZHLBv4 (ORCPT ); Tue, 11 Aug 2009 21:51:56 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:52082 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754348AbZHLBvz (ORCPT ); Tue, 11 Aug 2009 21:51:55 -0400 To: Amerigo Wang Cc: linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, Neil Horman , Andi Kleen , akpm@linux-foundation.org, Ingo Molnar References: <20090811104144.5154.77871.sendpatchset@localhost.localdomain> <4A82182C.1080501@redhat.com> From: ebiederm@xmission.com (Eric W. Biederman) Date: Tue, 11 Aug 2009 18:51:52 -0700 In-Reply-To: <4A82182C.1080501@redhat.com> (Amerigo Wang's message of "Wed\, 12 Aug 2009 09\:17\:32 +0800") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=76.21.114.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Rcpt-To: amwang@redhat.com, mingo@elte.hu, akpm@linux-foundation.org, andi@firstfloor.org, nhorman@redhat.com, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-DCC: XMission; sa01 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Amerigo Wang X-Spam-Relay-Country: X-Spam-Report: * -1.8 ALL_TRUSTED Passed through trusted hosts only via SMTP * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -2.6 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 XM_SPF_Neutral SPF-Neutral * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay Subject: Re: [RFC Patch 1/2] kexec: show memory info in /proc/iomem X-SA-Exim-Version: 4.2.1 (built Thu, 25 Oct 2007 00:26:12 +0000) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Amerigo Wang writes: >> Nacked-by: "Eric W. Biederman" >> >> We can inspect the image we are going to load to get this information. >> In fact /sbin/kexec already inspects the image we are going to load >> to get this information. Putting this in the kernel adds kernel >> complexity for no gain. >> > > /sbin/kexec is supported to know this, of course. But this is not for > /sbin/kexec, this is for user (or other programs) to observe the memory > information, so that he can know the memory he reserved is too much or not. > Without this, it is a little hard to use patch 2/2. So add on option to /sbin/kexec. Furthermore none of this does a good job of predicting how much memory /sbin/fsck will require to check the filesystem before we write a crash dump. The only way I know of reliably obtaining that kind of information is testing your crash userspace with different amounts of memory and understanding what is going on. Eric