Date: Sun, 26 Aug 2001 21:18:42 +0200 (CEST) From: Søren Schmidt <sos@freebsd.dk> To: sos@freebsd.dk Cc: Zhihui Zhang <zzhang@cs.binghamton.edu>, freebsd-hackers@FreeBSD.ORG Subject: Re: ata0-master: non aligned DMA transfer attempted Message-ID: <200108261918.f7QJIgM68585@freebsd.dk> In-Reply-To: <200108261917.f7QJHnT68379@freebsd.dk> =?ISO-8859-1?Q?from_S=F8ren_Schmidt_at_Aug_26=2C_2001_09=3A17=3A49_pm?=
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It seems Søren Schmidt wrote: > It seems Zhihui Zhang wrote: > > > > Thanks for your replay. I use gdb to find out that the buffer address is > > not 16-byte aligned. This leads to a question as to how to align a > > statically allocated data structure properly. Using union seems to be able > > to align you on a long boundary (or even long long?), but that is not 16 > > byte aligned. > > For all ATA controllers except for one crappy exception, the buffer > should just be on a 2byte aligned adresss, so using 16 or even > 64 bytes as Julian suggested is not needed. > > But you can ONLY transfer 512bytes at a time. Or a multiple there of... -Søren To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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