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    SubjectRe: [PATCH] Make math_state_restore() save and restore the interrupt flag
    On 02/01/2014 05:51 PM, Linus Torvalds wrote:
    > On Sat, Feb 1, 2014 at 5:47 PM, Suresh Siddha <sbsiddha@gmail.com> wrote:
    >>
    >> So if the restore failed, we should do something like drop_init_fpu(),
    >> which will restore init-state to the registers.
    >>
    >> for eager-fpu() paths we don't use clts() stts() etc.
    >
    > Uhhuh. Ok.
    >
    > Why do we do that, btw? I think it would make much more sense to just
    > do what I *thought* we did, and just make it a context-switch-time
    > optimization ("let's always switch FP state"), not make it a huge
    > semantic difference.
    >

    Twiddling CR0.TS is pretty slow if we're not taking advantage of it.

    -hpa




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