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Re: bzip2 unaligned trap

On Sat, Aug 27, 2005 at 06:46:38AM +0100, Paul Jakma wrote:
> On Fri, 26 Aug 2005, Steve Langasek wrote:

> >Unless they're running a fully ppc64 system (which is 
> >contraindicated by kernel and glibc upstream), they're not going to 
> >get the same unaligned traps on ppc as on alpha.

> See:

> 	arch/ppc/traps.c AlignmentException -> fix_alignment()
> 	arch/ppc/align.c -> fix_alignment

> Seems at least several models of PPC (all?) do trap on unaligned 
> access, the kernel just doesn't complain as it does on Alpha.

And which of the instructions on ppc32 requires 64-bit alignment?
That's really the big issue with alpha -- as a 64-bit arch, it has
instructions that take 64-bit words that have to be aligned on 8-byte
boundaries, which is not a condition that people used to writing code
for 32-bit archs will normally check for.

Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
vorlon@debian.org                                   http://www.debian.org/

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