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    SubjectRe: hammer: MAP_32BIT
    Timothy Miller wrote:
    >>
    >> The purpose is that there is a slight task-switching speed advantage if
    >> the address is in the bottom 4 GB. Since this affects every process,
    >> and most processes use very little TLS, this is worthwhile.
    >>
    >> This is fundamentally due to a K8 design flaw.
    >
    > Is there an explicit check somewhere for this? Are the page tables laid
    > out differently?
    >

    No, there are two ways to load the FS base register: use a descriptor,
    which is limited to 4 GB but is faster, or WRMSR, which is slower, but
    unlimited.

    -hpa

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