From owner-freebsd-current@FreeBSD.ORG  Wed Feb  7 09:20:59 2007
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From: Hans Petter Selasky <hselasky@c2i.net>
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Date: Wed, 7 Feb 2007 10:20:34 +0100
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Cc: Luigi Rizzo <rizzo@icir.org>
Subject: Re: C macro to find the next power of 2 ?
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Hi Luigi,

Why don't you hardcode the structures with the correct alignment, and maybe 
you find the __align() macro useful.

What you are discovering is an old issue. Hardware structures must be 
indexable without addition.

--HPS