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    SubjectRe: Crusoe's persistent translation on linux?

    Linus Torvalds wrote:
    > On Fri, 20 Jun 2003, Nuno Silva wrote:
    >>This raises a new question. How about a port of Linux to the "VLIW" so
    >>that we can skip x86 "code morphing" interelly?
    > The native crusoe code - even if it was documented and available - is not
    > very conductive to general-purpose OS stuff. It has no notion of memory
    > protection, and there's no MMU for code accesses, so things like kernel
    > modules simply wouldn't work.
    >>I'm sure that 1GHz would benefit from it. Is it possible, Linus?
    > The translations are usually _better_ than statically compiled native
    > code (because the whole CPU is designed for speculation, and the static
    > compilers don't know how to do that), and thus going to native mode is not
    > necessarily a performance improvement.
    > So no, it wouldn't really benefit from it, not to mention that it's not
    > even an option since Transmeta has never released enough details to do it
    > anyway. Largely for simple security concerns - if you start giving
    > interfaces for mucking around with the "microcode", you could do some
    > really nasty things.

    Authoritative answer received! :)

    Nuno Silva

    > Process startup is slightly slower due to the translation overhead, but
    > that doesn't matter for the kernel anyway (so a native kernel wouldn't
    > much help). And we do cache translations in memory, even across
    > invocations. I suspect the reason large builds are slower are due to slow
    > memory and/or occasionally overflowing the translation cache.
    > Linus

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