huang ying wrote:
On 9/21/07, Mika Penttilä <mika.penttila@xxxxxxxxxxx> wrote:
huang ying wrote:
On 9/21/07, Mika Penttilä <mika.penttila@xxxxxxxxxxx> wrote:
Usage:
1. Compile kernel with following options selected:
CONFIG_X86_32=y
CONFIG_RELOCATABLE=y # not needed strictly, but it is more convenient with it
CONFIG_KEXEC=y
CONFIG_CRASH_DUMP=y # only needed by kexeced kernel to save/restore memory image
CONFIG_PM=y
CONFIG_KEXEC_JUMP=y
2. Download the kexec-tools-testing git tree, apply the kexec-tools
kjump patches (or download the source tar ball directly) and
compile.
3. Download and compile the krestore tool.
4. Prepare 2 root partition used by kernel A and kernel B/C, referred
as /dev/hda, /dev/hdb in following text. This is not strictly
necessary, I use this scheme for testing during development.
5. Boot kernel compiled for normal usage (kernal A).
6. Load kernel compiled for hibernating/restore usage (kernel B) with
kexec, the same kernel as that of 5 can be used if
CONFIG_RELOCATABLE=y and CONFIG_CRASH_DUMP=y are selected.
The --elf64-core-headers should be specified in command line of
kexec, because only the 64bit ELF is supported by krestore tool.
For example, the shell command line can be as follow:
kexec -p -n /boot/bzImage --mem-min=0x100000 --mem-max=0xffffff
--elf64-core-headers --append="root=/dev/hdb single"
7. Jump to the hibernating kernel (kernel B) with following shell
command line:
kexec -j
8. In the hibernating kernel (kernel B), the memory image of
hibernated kernel (kernel A) can be saved as follow:
cp /proc/vmcore .
cp /sys/kernel/kexec_jump_back_entry .
Here we save also kernel B's pages.
No, the kernel B's pages will not be saved. Because when we build the
elfcore (/proc/vmcore) header, we exclude memory area used by kernel
B. The details can be found in kexec-tools patches.
Ok I see. But should the kernel B's e820 mem map be limited to 1m-16m in
order not to allocate pages found also in A's space? Or does does the
--mem-min and --mem-max do that also?
That is what "memmap=exactmap memmap=640K@0K memmap=15M@1M" for. The
contents of e820 memmap will be overrided when these kernel parameters
are specified.
Best Regards,
Huang Ying
Yes, you just didn't specify exactmap for kernel B in your instructions,
but only for C. But it is also required for kernel B then?
Thanks,
Mika
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