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    SubjectRe: [PATCH] XBox Gaming System subarchitecture.
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    On Mon, Jul 14, 2003 at 03:28:38PM +0100, Dave Jones wrote:
    > > The real patch contains cleaned up HZ-ifdefs.
    >
    > good good..

    Testing it an extra time now.

    > > Or as Christoph answered: "Oh well, stupid crappy hardware..."
    >
    > That's a possibility, but if that were the case, I'd expect other things
    > also to start randomly failing. It's unclear to me how -O2 would make
    > a hardware bug more aparent. If it did so, that would also mean you'd
    > have to ensure all your userspace was similarly compiled, which sounds
    > very suspect. It's just a celeron based PC with nvidia nforce chipset right ?
    > If that combination caused such problems, I'd expect to see the
    > occasional problem report from non-Xbox regular home-built PC users too.

    It only happens when paging is off. Hence no problem as soon as the kernel
    is up and running. -O2 changes the memory-access patterns so it is quite
    possible that it would expose hardware bugs.

    > Might be one worth picking over on the gcc lists if you can identify
    > which part gets miscompiled ?
    >
    > Tried different versions of binutils too ?

    On 1.0 xboxes it works with any gcc with or without optimizations on.

    On 1.1+ xboxen it does NOT work with 2.95, -O0 or -O2. But with 3.2.2-3.3 it
    is known to work with -O0.

    It's was not easy to localize the crashes. Cos adding more code for
    debugging moves the point where it crashes around. However it does crash
    reading from memory. A prefectly valid address. That it just a few
    instructions earlier had written and read from.

    --
    Anders Gustafsson - andersg@0x63.nu - http://0x63.nu/
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