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    SubjectRe: [RFC PATCH 0/6] jump label v3
    On 11/18/2009 03:07 PM, Roland McGrath wrote:
    >> 67 66 8D 74 00 (lea si,[si+0]) should work as a 32-bit atomic NOP. It's
    >> not necessarily the fastest, though (I have no data on that.)
    >> Similarly, 66 66 66 66 90 should also work.
    > We should get all the knowledge like that stored in places like the
    > Kconfig.cpu comments near X86_P6_NOP and/or asm/nops.h macros and comments.
    > Let's have an ASM_ATOMIC_NOP5 macro in asm/nops.h? I've lost track of the
    > variants, and I'll leave that to you all who are close to the chip people.
    > I can't tell if it's the case that there will be kernel configurations
    > where there is one known-safe choice but a different choice that's optimal
    > if CPU model checks pass. If so, we could compile in the safe choice and
    > then mass-change to the optimal choice at boot time. (i.e. like the
    > alternatives support, but we don't really need to use that too since we
    > already have another dedicated table of all the PC addresses to touch.)

    Yes, I believe we do something like that already.


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