Chuck Ebbert wrote:
> Chris Lesiak reported that changes to i386's __memcpy() broke his device
> because it can't handle byte moves and the new code uses them for
> all trailing bytes when the length is not divisible by four.  The old
> code tried to use a 16-bit move and/or a byte move as needed.
> 
> H. Peter Anvin:
> "There are only a few semantics that make sense: fixed 8, 16, 32, or 64
> bits, plus "optimal"; the latter to be used for anything that doesn't
> require a specific transfer size.  Logically, an unqualified
> "memcpy_to/fromio" should be the optimal size (as few transfers as
> possible)"
> 
> So add back the old code as __minimal_memcpy and have IO transfers
> use that.
> 

I was thinking some more about that, and I suspect the "right" way to do 
this looks something like the attached code.  Note that it assymetric, 
and that it's probably too long to inline.

I haven't tested this yet, and I probably won't have time to do so this 
evening.

	-hpa