Re: iomapping a big endian area

[Christoph Hellwig]

On Mon, Apr 04, 2005 at 08:59:03AM -0500, James Bottomley wrote:
> Well ... it's like this. Native means "pass through without swapping"
> and has an easy implementation on both BE and LE platforms.  Logically
> io{read,write}{16,32}be would have to do byte swaps on LE platforms.
> Being lazy, I'm opposed to doing the work if there's no actual use for
> it, so can you provide an example of a BE bus (or device) used on a LE
> platform that would actually benefit from this abstraction?

The IOC4 device that provides IDE, serial ports and external interrupts
on Altix systems has a big endian register layour, and the PCI-X bridge
in those Altix systems can do the swapping if a special bit is set.

In older kernels that bit was set from the driver through a special API,
but it seems the firmware does that automatically now.

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