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Date:      Thu, 28 Mar 2013 09:31:26 -0600
From:      Scott Long <scottl@samsco.org>
To:        Ian Lepore <ian@FreeBSD.org>
Cc:        Alexander Motin <mav@FreeBSD.org>, freebsd-current@FreeBSD.org, freebsd-stable@FreeBSD.org, Adrian Chadd <adrian@FreeBSD.org>
Subject:   Re: Any objections/comments on axing out old ATA stack?
Message-ID:  <B236C7CE-FCDF-4F2B-8480-1CEFE549171C@samsco.org>
In-Reply-To: <1364479253.36972.77.camel@revolution.hippie.lan>
References:  <51536306.5030907@FreeBSD.org> <CAJ-Vmon-8FaLa-=F=Z3dL85FPoRr%2Bp3kt%2Btr1fo7AkOV9hhyCA@mail.gmail.com> <5153EE86.8000801@FreeBSD.org> <1364479253.36972.77.camel@revolution.hippie.lan>

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On Mar 28, 2013, at 8:00 AM, Ian Lepore <ian@FreeBSD.org> wrote:

> On Thu, 2013-03-28 at 09:17 +0200, Alexander Motin wrote:
>> On 28.03.2013 02:43, Adrian Chadd wrote:
>>> My main concern with the new stuff is that it requires CAM and =
that's
>>> reasonably big compared to the standalone ATA code.
>>>=20
>>> It'd be nice if we could slim down the CAM stack a bit first; it =
makes
>>> embedding it on the smaller devices really freaking painful.
>>=20
>> Are there many boards now with ATA, but without USB? But I agree, it=20=

>> should be checked.
>>=20
>=20
> It's not necessarily what the boards have but how they're used.  We =
use
> industrial SBCs at work that have ata compact flash sockets on the =
board
> which we do use, and usb interfaces which we don't use.
>=20
> I've never tested the new ata+cam stuff on some of these boards, most
> based on Cyrix, Via, Geode, and VortexD86 chipsets.  The older ata =
code
> works, but not always very well -- for example, we usually have to set
> hw.ata.ata_dma=3D0 for absolutely no reason we've ever been able to =
figure
> out except that if we leave it enabled we get DMA errors and panics on
> some CF cards and not on others.  I have no idea whether to expect =
such
> things to be better, worse, or no different by changing to the ata+cam
> way of doing things (but I don't really have time to do extensive
> testing right now either).
>=20


The legacy ATA code was hard to maintain, very buggy (as you point out), =
and
is essentially unmaintained.  Also, IIRC, the legacy stack simply cannot =
support
NCQ tagged queueing.

I think that Alexander has done a superb job with both developing and =
supporting
the CAM_ATA stack.

Scott





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