Re: iomapping a big endian area

[James Bottomley]

On Tue, 2005-04-05 at 08:42 +0100, Russell King wrote:
> Not so.  There are two different styles of big endian.  (Lets just face
> it, BE is fucked in the head anyway...)
> 
> physical bus:	31...24	23...16	15...8	7...0
> 
> BE version 1 (word invariant)
>   byte access	byte 0	byte 1	byte 2	byte 3
>   word access	31-24	23-16	15-8	7-0
> 
> BE version 2 (byte invariant)
>   byte access	byte 3	byte 2	byte 1	byte 0
>   word access	7-0	15-8	23-16	31-24

These are just representations of the same thing.  However, I did
deliberately elect not to try to solve this problem in the accessors.  I
know all about the register relayout, because 53c700 has to do that on
parisc.

However, I don't think it's the job of the io accessors to remap the
register locations (primarily because the remapping depends on the
documentation:  a chip that's documented as BE on BE has no remapping
required.  Hoever, the same chip on LE would need this).


> And guess which architecture implements *both* of these...  Grumble.

We have this in parisc too ...

James


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