Re: [linux-pm] [RFC][PATCH 0/2 -mm] kexec based hibernation -v3

[Mika PenttilÃ]

huang ying wrote:
> On 9/21/07, Mika Penttilà <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?
Thanks,
Mika


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