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    SubjectRe: [ANNOUNCE][CFT] kexec for v2.5.48 && kexec-tools-1.7 -- Success Story!
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    Werner Almesberger <wa@almesberger.net> writes:

    > Eric W. Biederman wrote:
    > > The needed hooks are there. You can make certain an appropriate
    > > ->shutdown()/reboot_notifier method is present, or you can fix the driver
    > > so it can initialize the device from any random state.
    >
    > In the case of a crash, you may not be able to use the normal
    > shutdown, but there may still be pending bus master accesses, e.g.
    > from an on-going transfer, or free buffers that will eventually
    > (i.e. there's no use in "waiting for the operation to finish") get
    > used.
    >
    > Initializing the device from any state is certainly a good feature,
    > and it will cure the most visible symptoms, but problems may still
    > occur if the device decides to scribble over memory after leaving
    > the original kernel, and before the reset has occurred under the
    > new kernel. (Or did you mean to initialize before invoking kexec ?


    In this case I suspect the best route is to locate the kexec_on_panic
    buffers for kexec where we want to use them. Then even in most
    cases a devices is scribbling on memory, unless the device was
    improperly setup, it isn't scribbling on memory necessary to get
    the new kernel going.

    > I see several possible approaches for this:
    >
    > 0) do as bootimg did, and ignore the problem :-)
    > 1) try to call the regular device shutdown. In the case of a
    > crash, this may hang, or corrupt the system further.
    > 2) add a new callback that just silences the device, without
    > trying to clean things up. This is probably the best
    > long-term solution.

    Roughly that is ->shutdown() it was separated from the ->remove()
    case so that it could be stripped down to a minimal implementation.

    Eric
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