Date: Mon, 17 Dec 2001 19:48:45 -0700 From: Warner Losh <imp@harmony.village.org> To: Garrett Wollman <wollman@khavrinen.lcs.mit.edu> Cc: arch@FreeBSD.org Subject: Re: Please review: changes to MI bus code for sparc64 Message-ID: <200112180248.fBI2mjM81380@harmony.village.org> In-Reply-To: Your message of "Mon, 17 Dec 2001 21:36:17 EST." <200112180236.fBI2aHM39997@khavrinen.lcs.mit.edu> References: <200112180236.fBI2aHM39997@khavrinen.lcs.mit.edu> <20011213211544.A4747@crow.dom2ip.de> <20011213192033.A871@crow.dom2ip.de> <200112131901.fBDJ1hl02003@mass.dis.org> <20011213211544.A4747@crow.dom2ip.de>
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In message <200112180236.fBI2aHM39997@khavrinen.lcs.mit.edu> Garrett Wollman writes: : In article <200112180212.fBI2CUM81074@harmony.village.org> you write: : >I don't understand the difference between boundary and alignment. : : A boundary is a locus which an allocation must not cross. Consider, : for example, the crufty old ISA DMA hardware: 16-bit transfers need : only 16-bit alignment, but must not cross a 64-kbyte ``page'' : boundary, because the address-generation logic was kluged out of a : 16-bit DMA controller and an 8-bit latch. Ah. That makes perfect sense. It doesn't need 64kbyte alignment, but must not cross a 64kbyte boundary... Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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