cvs commit: src/share/man/man9 bus_dma.9
scottl at samsco.org
Wed Mar 1 15:50:40 PST 2006
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
>>> 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.
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