Date: Fri, 14 Sep 2001 15:02:45 -0600 From: Warner Losh <imp@harmony.village.org> To: Mike Smith <msmith@FreeBSD.ORG> Cc: Yar Tikhiy <yar@FreeBSD.ORG>, hackers@FreeBSD.ORG, msmith@mass.dis.org Subject: Re: Driver structures & alignment Message-ID: <200109142102.f8EL2jt24452@harmony.village.org> In-Reply-To: Your message of "Thu, 13 Sep 2001 16:09:57 PDT." <200109132309.f8DN9vX03967@mass.dis.org> References: <200109132309.f8DN9vX03967@mass.dis.org>
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In message <200109132309.f8DN9vX03967@mass.dis.org> Mike Smith writes:
: Any form of packing is going to cause problems for items that are
: located in illegal fashions.
It is almost more appropriate to use bus_space_{read,write} than using
memory mapped structures. The bus macros will work for otherwise
unaligned thigns, while direct access won't. Also, the
compiler/system may optimize things in strange ways that cause
problems. Do yourself a big favor and don't go down this path.
Warner
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