Kexec base hibernation has some potential advantages over uswsusp and

TuxOnIce (suspend2). Some most obvious advantages are:
1. The hibernation image size can exceed half of memory size easily.
2. The hibernation image can be written to and read from almost

   anywhere, such as USB disk, NFS.
3. It is possible to eliminate freezer from kexec based hibernation

   implementation.
4. Based on kexec/kdump implementation, the kernel code needed is

   less.
This patch set implements the kexec based hibernation. The kernel

functionality added are as follow:
1. Jumping between the kexeced kernel and the original kernel. This is

   used by hibernation to save/load necessary state in original kernel

   and jumping back to original kernel after restore the memory of

   original kernel.
2. Add writing support to /dev/oldmem. This is used by hibernation to

   restore the memory of original kernel.
The hibernation procedure with the patch set is as follow:
1. Boot a kernel A
2. Work under kernel A
3. Kexec another kernel B (crash dump enabled) in kernel A.
4. Save the memory image of kernel A through crash dump (such as "cp

   /proc/vmcore ~"). Save the "jump back entry".
5. Shutdown or reboot
The restore process with the patch set is as follow:
1. Boot a kernel C (crash dump enabled), the memory area used by

   kernel C must be a subset of memory area used by kernel B.
2. Restore the memory image of kernel A through /dev/oldmem. Restore

   the "jump back entry".
3. Jump from kernel C back to kernel A
4. Continue work under kernel A
The following user-space tools are needed to implement hibernation and

restore.
1. kexec-tools needs to be patched to support kexec jump. The patches

   and the precompiled kexec can be download from the following URL:

       source: http://khibernation.sourceforge.net/download/release_20070920/kexec-tool...

       patches: [ message continues ]