Date: Wed, 01 Mar 2006 16:50:39 -0700 From: Scott Long <scottl@samsco.org> To: John-Mark Gurney <gurney_j@resnet.uoregon.edu> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, Ruslan Ermilov <ru@FreeBSD.org>, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/share/man/man9 bus_dma.9 Message-ID: <4406334F.7070205@samsco.org> In-Reply-To: <20060301233327.GQ840@funkthat.com> References: <200602281958.k1SJwvGL051504@repoman.freebsd.org> <20060301232621.GF29183@ip.net.ua> <20060301233327.GQ840@funkthat.com>
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John-Mark Gurney wrote: > Ruslan Ermilov wrote this message on Thu, Mar 02, 2006 at 01:26 +0200: > >>On Tue, Feb 28, 2006 at 07:58:57PM +0000, John-Mark Gurney wrote: >> >>>jmg 2006-02-28 19:58:57 UTC >>> >>> FreeBSD src repository >>> >>> Modified files: >>> share/man/man9 bus_dma.9 >>> Log: >>> update examples to use the correct terms that was never updated when the >>> earlier descriptions were gone over... >>> >>> MFC after: 3 days >>> >>> Revision Changes Path >>> 1.32 +3 -3 src/share/man/man9/bus_dma.9 >>> >> >>Not enough of fixing: "DMA read" and "DMA write" are also entangled here. > > > Nope... WRITE == DMA read... Read the descriptions of the flags > very carefully... If you aren't confused, you don't understand it.. > The reason you're confused is the reason why everyone gets it wrong, > and no one ever gets it correct the first time trying to figure out > which one to use... > Think of it from the perspective of the driver doing an operation. If the driver is reading a block off the disk, then you want to use the PREREAD/POSTREAD operations. Likewise for writes. It is done this way for clarity in the driver. I can't imagine how many bugs we'd have if write == read in the driver sources. Scott
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