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    SubjectRe: [RFC][PATCH] x86: make text_poke() atomic

    On Mon, 2 Mar 2009, Arjan van de Ven wrote:
    > .... but text_poke() realistically needs to call stop_machine() since
    > you can't poke live code.... so that makes me wonder how useful this
    > is...

    Well, not always. There's at least two cases where we don't need it:

    - in the UP -> SMP transition.

    - perhaps more interestingly, we're still kind of waiting for the
    resolution of the whole "nop out the first byte to a single-byte 'irq3'
    trap instruction, then rewrite the rest of the instruction, and then
    reset the first byte of the final instruction" thing.

    IOW, there are possible non-stop_machine() models where rewriting
    instructions in a live system does work, and quite frankly, I think we
    need them. Making the rule be the (obviously safe) "we can only do this in
    stop_machine" is quite possibly not going to be an acceptable rule and we
    may need alternatives.


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