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    SubjectRe: [PATCH 1/4 -mm] kexec based hibernation -v7 : kexec jump
    Hi!

    > This patch implements the functionality of jumping between the kexeced
    > kernel and the original kernel.
    >
    > To support jumping between two kernels, before jumping to (executing)
    > the new kernel and jumping back to the original kernel, the devices
    > are put into quiescent state, and the state of devices and CPU is
    > saved. After jumping back from kexeced kernel and jumping to the new
    > kernel, the state of devices and CPU are restored accordingly. The
    > devices/CPU state save/restore code of software suspend is called to
    > implement corresponding function.
    >
    > To support jumping without reserving memory. One shadow backup page
    > (source page) is allocated for each page used by new (kexeced) kernel
    > (destination page). When do kexec_load, the image of new kernel is
    > loaded into source pages, and before executing, the destination pages
    > and the source pages are swapped, so the contents of destination pages
    > are backupped. Before jumping to the new (kexeced) kernel and after
    > jumping back to the original kernel, the destination pages and the
    > source pages are swapped too.
    >
    > A jump back protocol for kexec is defined and documented. It is an
    > extension to ordinary function calling protocol. So, the facility
    > provided by this patch can be used to call ordinary C function in real
    > mode.
    >
    > A set of flags for sys_kexec_load are added to control which state are
    > saved/restored before/after real mode code executing. For example, you
    > can specify the device state and FPU state are saved/restored
    > before/after real mode code executing.
    >
    > The states (exclude CPU state) save/restore code can be overridden
    > based on the "command" parameter of kexec jump. Because more states
    > need to be saved/restored by hibernating/resuming.
    >
    > Signed-off-by: Huang Ying <ying.huang@intel.com>

    I'm not kexec hacker... but maybe this is in good enough state to be
    merged? It is useful on its own: kexec jump and back means we can dump
    system then continue running, for example...

    Pavel

    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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