Subject: Re: ELF ABI query
To: None <>
From: David Laight <>
List: port-arm
Date: 11/30/2001 20:32:07
> >  > Can you disable unaligned access (so they cause a trap)?
> > 
> > It is possible to do so, I believe; I'll have to peek at the ARM ARM
> > again.
> Yes, on some processors, it depends on the MMU.  If it is supported it is 
> controlled by bit 1 of cp15 r1.  Use CPU_CONTROL_AFLT_ENABLE from 
> arm/armreg.h
> > 
> >  > If so, should we enable it when loading ELF programs?
> > 
> > That certainly might be useful; it would save a lot of debugging, I'm sure.
> Yes.  Certainly we should try to make use of this feature.

Beware that certain versions of gcc with certain flag setting use
misaligned accesses when reading 16-bit data items.....

I have also been told that some future ARM cpus might support
misaligned transfers - but I don't know any details.