> 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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