From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760581AbYFLNDS (ORCPT ); Thu, 12 Jun 2008 09:03:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754419AbYFLNDI (ORCPT ); Thu, 12 Jun 2008 09:03:08 -0400 Received: from mx1.redhat.com ([66.187.233.31]:52972 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752808AbYFLNDH (ORCPT ); Thu, 12 Jun 2008 09:03:07 -0400 Date: Thu, 12 Jun 2008 09:02:25 -0400 From: Vivek Goyal To: "Huang, Ying" Cc: "Eric W. Biederman" , Pavel Machek , nigel@nigel.suspend2.net, "Rafael J. Wysocki" , Andrew Morton , linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, Kexec Mailing List Subject: Re: [PATCH -mm 2/2] kexec jump -v11: save/restore device state Message-ID: <20080612130225.GA9654@redhat.com> References: <1213082106.22608.30.camel@caritas-dev.intel.com> <20080611163026.GG6450@redhat.com> <1213232019.21353.8.camel@caritas-dev.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1213232019.21353.8.camel@caritas-dev.intel.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 12, 2008 at 08:53:39AM +0800, Huang, Ying wrote: > On Wed, 2008-06-11 at 12:30 -0400, Vivek Goyal wrote: > [...] > > > Usage example of simple hibernation: > > > > > > 1. Compile and install patched kernel with following options selected: > > > > > > CONFIG_X86_32=y > > > CONFIG_RELOCATABLE=y > > > CONFIG_KEXEC=y > > > CONFIG_CRASH_DUMP=y > > > CONFIG_PM=y > > > > > > 2. Build an initramfs image contains kexec-tool and makedumpfile, or > > > download the pre-built initramfs image, called rootfs.gz in > > > following text. > > > > > > 3. Prepare a partition to save memory image of original kernel, called > > > hibernating partition in following text. > > > > > > 4. Boot kernel compiled in step 1 (kernel A). > > > > > > 5. In the kernel A, load kernel compiled in step 1 (kernel B) with > > > /sbin/kexec. The shell command line can be as follow: > > > > > > /sbin/kexec --load-preserve-context /boot/bzImage --mem-min=0x100000 > > > --mem-max=0xffffff --initrd=rootfs.gz > > > > > > 6. Boot the kernel B with following shell command line: > > > > > > /sbin/kexec -e > > > > > > 7. The kernel B will boot as normal kexec. In kernel B the memory > > > image of kernel A can be saved into hibernating partition as > > > follow: > > > > > > jump_back_entry=`cat /proc/cmdline | tr ' ' '\n' | grep kexec_jump_back_entry | cut -d '='` > > > echo $jump_back_entry > kexec_jump_back_entry > > > cp /proc/vmcore dump.elf > > > > > > Then you can shutdown the machine as normal. > > > > > > 8. Boot kernel compiled in step 1 (kernel C). Use the rootfs.gz as > > > root file system. > > > > > > > One of the concerns raised by hibernation people in the past was to use > > single boot loader entry to boot normally as well while resuming a kernel. > > > > So in this case a user either needs to maintain two boot-loader entries > > or modify it on the fly. I wished there was a better way to handle that. > > Now it is not needed to have two boot-loader entries, just one is > enough. Step 4 and step 8 can share the same boot-loader entries. The > rootfs.gz can be the normal initramfs or initrd when deployment. In > rootfs.gz, if there is a valid hibernation image, the hibernated system > will be restored, otherwise, normal boot process follows. > Few things I don't understand. - Are you saying that hibernated image will be saved in initrd (rootfs.gz)? But that saving is only in RAM, we never write back it to disk? - I thought we probably have to dedicate a raw partition kind of thing for saving image and then modify boot loader command line to something similar to, "resume=partition". Then initrd can go hunting for image in respective partition (as specified by command line parameter) and if image is not available then continue with normal boot. Thanks Vivek