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SubjectRe: [RFC] [PATCH] cache pollution aware __copy_from_user_ll()

Thanks for your suggestions.

On 8/17/05, Akira Tsukamoto <> wrote:
> Anyway, going back to copy_user topic,
> big remaining issues are
> 1)store/restore floating point register (80/64bytes) twice every time by
> surrounding with kernel_fpu_begin()/kernel_fpu_end() is big penalty

I don't know. If nobody uses MMX/XMM, then there is no need
to save and restore.

> 2)after pagefault not always come back to copy function and corrupts fp register

I'm trying to understand this mechanism but I don't
understand very well.

> 3)disabling long preemption
> Please correct me if I am wrong.
> I tried to implement fpsave inside pagefault handler once and here is my junk;
> never had a time to finish it. Hiro, does it help you?

Thanks. I'm reading your patch but could not understand very well.

I'll ask you.

Hiro Yoshioka
mailto:hyoshiok at
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