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    SubjectRe: [BK+PATCH] remove __constant_memcpy

    On Thu, 17 Apr 2003, Jeff Garzik wrote:
    >
    > If DTRT means just using the existing code for large copies in general,
    > that's easy enough... patch attached.

    Yeah, this looks more palatable. It gets rid of a rather ugly thing, with
    no loss in generality _and_ if gcc ever tries to use sse2 for small
    copies, we can file that as a valid bug (there's just no way it's a good
    idea considering the costs of FP state even in user space)

    > 1) where did the 486 string ops go?

    They were disabled forever, because nobody cared enough, and they had
    known (or at least strongly suspected) bugs.

    > 2) why no sse2-optimized memcpy? just that noone has done one yet?

    Yes. If you want to, it's definitely the right thing to do. More so than
    the 3dnow stuff that is by now ancient. HOWEVER, I don't think there are
    any really valid large memcpy() calls inside the kernel. All the valid
    ones are either special-cased (ie "copy_page()") or to user space.

    So I wouldn't worry about it at a memcpy() level.

    Linus

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