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    SubjectRe: New resources - pls, explain :-(
    On Fri, Aug 13, 1999 at 02:36:10PM -0400, Peter Desnoyers wrote:

    > The only cases I have insight into are PCI drivers, where the swapping
    > points on bigendian machines can be:
    >
    > - none, all device registers are little-endian
    > - on the motherboard, flip all memread32/memwrite32 but no DMA access
    > (the hardware folks at work believe this exists somewhere, but I haven't
    > seen it)

    SNI's ASICPCI chipset used for example in the RM200C features 15 16mb
    windows for each of which byteorder swapping can be configured independantly.

    We neither support such a mapping feature in our current APIs nor is
    having drivers rely on the presence of such a feature a good idea unless
    it's present in all machines of a certain architecture.

    > - on the motherboard, selectable on a page-by-page basis (ultrasparc?)
    > - on the card - one or more areas can be configured to flip byte order
    > to big-endian
    >
    > I'm assuming that there are no PCI devices where device registers are
    > always big-endian. (is that true for all weird Mac cards?) Handling of
    > cases is:

    The SGI IOC3 is one example for such a card. Registers in PCI config
    space are little endian as per PCI spec. Other registers are big endian.

    Anybody PDP endian ;-)

    Ralf

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