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    SubjectRe: New kernel/resource.c

    On Sun, 25 Jul 1999, Linus Torvalds wrote:
    >
    > On Sun, 25 Jul 1999, Richard Henderson wrote:
    > >
    > > Hmm, actually we have more than 65536 generically on PCI. It's
    > > just the x86 that limits to 64k. I actually ran into trouble
    > > here the other day --
    >
    > Yeehaa..
    >
    > I wonder how many devices decode all 32 bits of an IO address. Maybe they
    > all do, but it sure hasn't gotten any testing by anybody. Considering that

    They aren't PCI compliant if they don't decode all 32 bits. Extract from
    PCI v2.1 spec:

    "The I/O Read command is used to read data from an agent mapped in I/O
    Address Space. AD[31::00] provide a byte address. All 32 bits must be
    decoded."

    Ditto for I/O write. The area where PCI devices are likely to cheat on
    address decoding is in the IO/mem base address regs, where some bits may
    be hardwired to zeros.


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