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Date:      Mon, 18 Dec 2000 15:57:55 -0800
From:      Brooks Davis <brooks@one-eyed-alien.net>
To:        "David W. Chapman Jr." <dwcjr@inethouston.net>
Cc:        stable <stable@FreeBSD.ORG>
Subject:   Re: DMA33 ATAPI CDROM and 4.2-STABLE
Message-ID:  <20001218155755.A16179@Odin.AC.HMC.Edu>
In-Reply-To: <01a501c0694d$c0865040$931576d8@inethouston.net>; from dwcjr@inethouston.net on Mon, Dec 18, 2000 at 05:53:42PM -0600
References:  <015d01c0694b$c34952c0$931576d8@inethouston.net> <20001218154939.A15680@Odin.AC.HMC.Edu> <01a501c0694d$c0865040$931576d8@inethouston.net>

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On Mon, Dec 18, 2000 at 05:53:42PM -0600, David W. Chapman Jr. wrote:
> >
> > DMA is disabled by default for ATAPI devices like CD-ROM drives because
> > many report that the support it but just crash your system if you
> > actually try to use it.  If you really want that virtualy useless
> > speedup you can enable the option ATA_ENABLE_ATAPI_DMA in your kernel
> > config.
> >
> I actually have that option compiled in my kernel, not that I need the
> speedup, unless it is slowing down my dma66 harddrive.

That was a rather important piece of missing information.  If this
worked before then you've got a bug and should file a PR, if not, you
probably don't.  At this point if it never worked in DMA mode before,
then your CDROM most likely doesn't have DMA support.  It is slowing
down your HD though how much I don't know since I know sos committed
code at some point that sped it up quite a bit.  There are a number of
reasons why that master-slave crap is gone from Serial-ATA.

-- Brooks

-- 
Any statement of the form "X is the one, true Y" is FALSE.


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