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    SubjectRe: [PATCH 0/2] Kexec jump: The first step to kexec base hibernation
    Date
    On Thursday, 12 July 2007 19:09, Huang, Ying wrote:
    > On Wed, 2007-07-11 at 22:48 -0700, Jeremy Fitzhardinge wrote:
    > > >> The kexec jump is implemented in the framework of software suspend. In
    > > >> fact, the kexec based hibernation can be seen as just implementing the
    > > >> image writing and reading method of software suspend with a kexeced
    > > >> Linux kernel.
    > > >>
    > >
    > > I guess I'm (still) confused by the terminology here. Do you mean that
    > > it fits into suspend-to-disk as a disk-writing mechanism, or in
    > > suspend-to-ram as a way of going to sleep?
    >
    > It fits into suspend-to-disk as a disk-writing mechanism. But most
    > tricks of suspend-to-disk will be no longer necessary in kexec based
    > hibernation.
    >
    > > > I didn't understand the ACPI problem. Does this mean that CONFIG_ACPI must
    > > > be disabled in the to-be-hibernated kernel, or in the little transient
    > > > kexec kernel?
    > > >
    > >
    > > I think the point is that if kernel A says "I'm suspending" and calls
    > > the suspend method on all its devices, then kernel B finds that it has
    > > no powered on devices to work with. But then couldn't it turn on the
    > > ones it wants anyway? And don't you want to suspend them, to make sure
    > > they're not still DMAing memory while B is trying to shuffle everything
    > > off to disk?
    >
    > The devices should be put quiescent state to stop DMA like things. But
    > they do not need to be put in low power state.

    Exactly. Morover, I don't think it would be correct to put them into low power
    states.

    Greetings,
    Rafael


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