Subject: Re: Kernel copyin/out optimizations for ARM...
To: David Laight <>
From: Richard Earnshaw <>
List: port-arm
Date: 03/15/2002 09:54:15
> > 
> > I've written a new copyin this afternoon.  1 byte xfers are
> > 15 instructions - 2 jumps, no register saves.
> ok, copyin, copyout and kcopy all written.
> kcopy is tested, the other should just work - code is the same.
> see then netbsd/bcopyinout.S
> I#m out till tomorrow - anyone feeling brave?

Looks pretty good, though I haven't tried it.

One thing I've noticed by inspection is that we are using ldr(t) + masking 
for in_short.  This may start to fail on future kernels 'cos we may well 
turn on strict alignment checking.  Can you fix that bit to use ldrb(t) 
plus an orr?