Re: RFC: Devices, buses and hotplug

Roger Gammans (rgammans@computer-surgery.co.uk)
Mon, 7 Jun 1999 19:54:09 +0100

In article <199906061910.MAA30421@pizda.davem.net>, David S. Miller
<davem@redhat.com> writes
> Anyway... one question. Who does the byte swapping, the host CPU
> or the peripheral?
>
> If the answer is 'host CPU', then my response is I can write clean
> code that is faster because it takes advantage of big endian
> peripheral support.
>
>Nope, the host CPU does it, but at _ZERO_ cost. You have two ways
>usually to get it done:
>
>1) Load/Store instruction attributes:
>
>2) MMU translations

Erm. There is a third way it could be done. I don't know about any
specific implementations but the Backplane/bus bridge could implement
byte swapping merely by the way the data lines are connected.

If I had this problem and was building a motherboard, I would seriously
consider going this route, unless there was a good reason not to.

Judging by the rest of this thread I assume no-one does it, which is a
shame. But I suppose if endian-ness was never specified.... sigh.

TTFN

-- 
Roger Gammans
"If I have trouble installing Linux, something is wrong. Very wrong."
                -- Linus Torvalds


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