From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Date: Wed, 05 Apr 2006 02:49:49 +0000 Subject: Re: [Fastboot] [PATCH] kexec on ia64 Message-Id: List-Id: References: <08B1877B2880CE42811294894F33AD5C053A82@pdsmsx411.ccr.corp.intel.com> <20060405101243.e3e4f772.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20060405101243.e3e4f772.kamezawa.hiroyu@jp.fujitsu.com> (KAMEZAWA Hiroyuki's message of "Wed, 5 Apr 2006 10:12:43 +0900") MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: KAMEZAWA Hiroyuki Cc: "Zou, Nanhai" , khalid_aziz@hp.com, linux-kernel@vger.kernel.org, fastboot@lists.osdl.org, linux-ia64@vger.kernel.org KAMEZAWA Hiroyuki writes: > Hi, I have a question about kexec/kdump. > > How does kdump know memory layout (of old kernel) now ? > > I'm working for memory hotplug. When memory is hot-added, memory layout changes. > But I think there is no code to manage memory layout information of added > memory. It is passed from one kernel to another, and it is memorized when you load the crash dump kernel. If your memory layout changes you need to reload the crash dump kernel from user space with the appropriate hotplug script. Unless this happens often it shouldn't be a problem. And yes this does leave a small race during which kexec on panic won't work. Eric From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751088AbWDECvE (ORCPT ); Tue, 4 Apr 2006 22:51:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751085AbWDECvE (ORCPT ); Tue, 4 Apr 2006 22:51:04 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:61587 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1751084AbWDECvC (ORCPT ); Tue, 4 Apr 2006 22:51:02 -0400 To: KAMEZAWA Hiroyuki Cc: "Zou, Nanhai" , khalid_aziz@hp.com, linux-kernel@vger.kernel.org, fastboot@lists.osdl.org, linux-ia64@vger.kernel.org Subject: Re: [Fastboot] [PATCH] kexec on ia64 References: <08B1877B2880CE42811294894F33AD5C053A82@pdsmsx411.ccr.corp.intel.com> <20060405101243.e3e4f772.kamezawa.hiroyu@jp.fujitsu.com> From: ebiederm@xmission.com (Eric W. Biederman) Date: Tue, 04 Apr 2006 20:49:49 -0600 In-Reply-To: <20060405101243.e3e4f772.kamezawa.hiroyu@jp.fujitsu.com> (KAMEZAWA Hiroyuki's message of "Wed, 5 Apr 2006 10:12:43 +0900") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org KAMEZAWA Hiroyuki writes: > Hi, I have a question about kexec/kdump. > > How does kdump know memory layout (of old kernel) now ? > > I'm working for memory hotplug. When memory is hot-added, memory layout changes. > But I think there is no code to manage memory layout information of added > memory. It is passed from one kernel to another, and it is memorized when you load the crash dump kernel. If your memory layout changes you need to reload the crash dump kernel from user space with the appropriate hotplug script. Unless this happens often it shouldn't be a problem. And yes this does leave a small race during which kexec on panic won't work. Eric