Date: Sat, 15 Sep 2001 14:44:11 -0600 From: Warner Losh <imp@harmony.village.org> To: hackers@FreeBSD.ORG Cc: Yar Tikhiy <yar@FreeBSD.ORG>, Mike Smith <msmith@FreeBSD.ORG>, msmith@mass.dis.org Subject: Re: Driver structures & alignment Message-ID: <200109152044.f8FKiBW02752@harmony.village.org> In-Reply-To: Your message of "Sat, 15 Sep 2001 12:26:15 PDT." <20010915122615.A72222@dragon.nuxi.com> References: <20010915122615.A72222@dragon.nuxi.com> <20010915110337.B53569@dragon.nuxi.com> <yar@freebsd.org> <200109132309.f8DN9vX03967@mass.dis.org> <20010914122344.A38530@snark.rinet.ru> <20010915110337.B53569@dragon.nuxi.com> <200109151813.f8FIDwW02011@harmony.village.org>
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In message <20010915122615.A72222@dragon.nuxi.com> "David O'Brien" writes: : On Sat, Sep 15, 2001 at 12:13:58PM -0600, Warner Losh wrote: : > In message <20010915110337.B53569@dragon.nuxi.com> "David O'Brien" writes: : > : It is best to order this from largest to smallest size if you are worried : > : about alignment holes, etc. : > : : > : int64_t d; /* 8-byte boundary */ : > : int32_t c; /* 4-byte boundary */ : > : int32_t f; /* 4-byte boundary */ : > : int16_t a; : > : int16_t b; : > : int8_t e[4]; : > : > unfortunately, there are many device structures that are passed around : > via DMA and hte like that don't let you do this... : : How come? The struct represents some [semi-]physical organization? Because the hardware designer may have done silly things. These are hardware data structures. Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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