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    SubjectRe: [PATCH 1/10] Cr4 is valid on some 486s

    On Fri, 11 Nov 2005, Zachary Amsden wrote:
    > Yes, this is fine, but is it worth writing the feature discovery code? I
    > suppose it doesn't matter, as it gets jettisoned after init. I guess it is
    > just preference.

    Well, you could do the feature discovery by trying to take a fault early
    at boot-time. That's how we verify that write-protect works, and how we
    check that math exceptions come in the right way..

    > Could we consider doing the same with LOCK prefix for SMP kernels booted on
    > UP? Evil grin.

    Not so evil - I think it's been discussed. Not with alternates (not worth
    it), but it wouldn't be hard to do: just add a new section for "lock
    address", and have each inline asm that does a lock prefix do basically

    lock ; xyzzy

    .section .lock.address
    .long 1b

    and then just walk the ".lock.address" thing and turn all locks into 0x90

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