Subject: Re: ELF ABI query
To: None <port-arm@netbsd.org>
From: David Laight <David.Laight@btinternet.com>
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.
David