[PATCH] ARM: remove ixp2000 platform

Russell King - ARM Linux linux at arm.linux.org.uk
Wed Mar 7 04:14:09 EST 2012


On Wed, Mar 07, 2012 at 09:40:31AM +0100, Linus Walleij wrote:
> Network equipment seems to like using BE.
> 
> I have some vague idea that this is beacuse IP packets are big
> endian, and thus you can process them quickly by just casting fields
> to e.g. u32 pointers and read them.
> 
> I don't know if this is true, but seems to much of a correlation to
> be pure coincidence. Thus a pretty interesting subject in
> embedded ARM not used for tablets/mobile/generic computing
> kind of stuff.

ISTR Nicolas explained this to me as being an established thing in the
comms sector.  They expect BE and only understand BE.

I did point out that you end up with many more endian conversions by
going to BE, mainly because PCI is LE and all your PCI accesses have
to be endian-swapped.  So in terms of bandwidth, I'd expect an ARM
PCI platform running in BE mode to have worse throughput than a LE
PCI platform.

But... if BE allows the comms people to keep their warm fuzzy feeling
who are we to argue.



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