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    SubjectRe: Patch for K6 sep flag
    Brian Gerst wrote:
    >
    > This patch fixes /proc/cpuinfo for the K6 model 6. On this version of
    > the K6, bit 10 of the extended flags register denotes the SYSCALL/SYSRET
    > capability. On later models, bit 11 (the same as the PPro/PII) is used.

    Digging a bit deeper into AMD's documentation, I found that this is only
    true for the stepping A of the model 6. Beginning with the B step model
    6, bit 11 is used for SYSCALL/SYSRET. Bit 10 is now marked as
    "reserved", and probably should be ignored. I've been experimenting
    with implementing a SYSCALL handler, but the MSR that controls it seems
    to be unimplemented on my chip (K6-233, model 6, C step). I've wanted
    to upgrade anyways, so this is more incentive...

    In short, my previous patch doesn't really work as advertised. Bit 10
    now is either advertising a feature AMD isn't telling anybody about, or
    it is erroneous.

    PS. A while back (a year ago?) somebody had posted a patch that started
    to implement SYSCALL. Does anybody remember who posted it or where I
    can find it?

    --

    Brian Gerst

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