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
