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Date: Thu, 03 Aug 2006 11:52:21 -0700
From: Peter Grehan <grehan@freebsd.org>
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To: Maxim Sobolev <sobomax@FreeBSD.org>
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Cc: freebsd-ppc@FreeBSD.org
Subject: Re: Unaligned 64-bits access on FreeBSD/powerpc
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> Well, actually *nix has a long history of just killing the program with 
> SIGBUS in such case.
> 
> I am just wondering if it's really expected behavior on FreeBSD/powerpc 
> or not.

  No :(

  What system are you running on ? I was pretty sure that G3/G4 CPUs 
allowed unaligned accesses unless you explicitly disabled it (except for 
cases such as vector ops). A 64 bit op on these CPUs should decompose 
into separate 32-bit accesses ala i386 so the same case should occurr 
for unaligned 32-bit ops.

  In any event, the default should be that unaligned accesses are 
handled, and then have switches to optionally uprintf the address, or 
SIGBUS.

later,

Peter.