Date: Thu, 13 Sep 2001 16:09:57 -0700 From: Mike Smith <msmith@freebsd.org> To: Yar Tikhiy <yar@freebsd.org> Cc: hackers@freebsd.org, msmith@mass.dis.org Subject: Re: Driver structures & alignment Message-ID: <200109132309.f8DN9vX03967@mass.dis.org> In-Reply-To: Message from Yar Tikhiy <yar@freebsd.org> of "Thu, 13 Sep 2001 23:23:52 %2B0400." <20010913232352.A23874@snark.rinet.ru>
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> Hi there, > > Is there a single blessed way to define packed structures > for use in drivers? I suspect that using "#pragma pack(1)" > will lead to alignment errors in non-Intel architectures. Any form of packing is going to cause problems for items that are located in illegal fashions. Having said that, I recommend using __attribute__ ((packed)) to explicitly request that a structure be packed. > Should char arrays be used for all multi-byte elements to > avoid alignment problems? No. > And is it OK to rely on specially crafted structures, like > "struct fs" in /sys/ufs/ffs/fs.h where multi-byte elements > are pre-aligned by the structure's design, being contiguous? "rely" in what fashion? To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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