Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262617AbVBCH2g (ORCPT ); Thu, 3 Feb 2005 02:28:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262596AbVBCH2g (ORCPT ); Thu, 3 Feb 2005 02:28:36 -0500 Received: from sv1.valinux.co.jp ([210.128.90.2]:45804 "EHLO sv1.valinux.co.jp") by vger.kernel.org with ESMTP id S262994AbVBCH2G (ORCPT ); Thu, 3 Feb 2005 02:28:06 -0500 Date: Thu, 03 Feb 2005 16:28:10 +0900 From: Itsuro Oda To: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [Fastboot] [PATCH] Reserving backup region for kexec based crashdumps. Cc: Koichi Suzuki , Vivek Goyal , Andrew Morton , fastboot , lkml , Maneesh Soni , Hariprasad Nellitheertha , suparna bhattacharya In-Reply-To: References: <4200861B.7040807@intellilink.co.jp> Message-Id: <20050203154433.18E4.ODA@valinux.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.10.04 [ja] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1531 Lines: 40 Hi, On 02 Feb 2005 08:24:03 -0700 ebiederm@xmission.com (Eric W. Biederman) wrote: > > So the kernel+initrd that captures a crash dump will live and execute > in a reserved area of memory. It needs to know which memory regions > are valid, and it needs to know small things like the final register > state of each cpu. Exactly. Please let me clarify what you are going to. 1) standard kernel: reserve a small contigous area for a dump kernel (this is not changed as the current code) 2) standard kernel: export the information of valid physical memory regions. (/proc/iomem or /proc/cpumem etc.) 3) kexec (system call?): store the information of valid physical memory regions as ELF program header to the reserved area (mentioned 1)). 4) standard kernel: when a panic occur, append (ex.) the register information as ELF note after the memory information (if necessary). and jump new kernel 5) dump kernel: export all valid physical memory (and saved register information) to the user. (as /dev/oldmem /proc/vmcore ?) Is this correct ? one question: how the dump kernel know the saved area of ELF headers ? one more question: I don't understand what the 640K backup area is. Please let me know why it is necessary. Thanks. -- Itsuro ODA - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/