From owner-freebsd-current  Mon Dec  9  2:35:18 2002
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From: Soeren Schmidt <sos@spider.deepcore.dk>
Message-Id: <200212091034.gB9AYvp2099124@spider.deepcore.dk>
Subject: Re: ATACD issues slowly coming back...
In-Reply-To: <3DF4689F.5040702@lflat.org>
To: Vadim Belman <voland@lflat.org>
Date: Mon, 9 Dec 2002 11:34:57 +0100 (CET)
Cc: Bruce Cran <bruce@cran.org.uk>, current@FreeBSD.ORG
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It seems Vadim Belman wrote:
> 
> 
> Bruce Cran wrote:
> 
> > Your CD drive should indeed support UDMA33 - my DVD drive supports
> > UDMA33, and my CDRW supports multi-word DMA, even though my BIOS only
> > ever configures it for PIO4, and my DVD for UDMA33.   FreeBSD only ever
> > configures them for PIO during bootup, but, using the atacontrol
> > program, it configures them both for maximum speed, even knowing they
> > _can_ only do UDMA33,WDMA2.
> 
> 	If you have a look at sysctl hw.ata tree, it'll give you the clue on 
> how to overcome this behaviuor. In simple words, what you need is to poot
> 
> hw.ata.atapi_dma=1
> 
> 	in your /boot/loader.conf and have the nirvana of automatic DMA 
> detection...

And remember the warning that it does not always work as expected, ATAPI
DMA is a many headed monster...

-Søren

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