Re: ata(4) and NCQ

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Tue, Apr 26, 2011 at 07:18:47PM +0000, Jonathan A. Kollasch wrote:
> On Tue, Apr 26, 2011 at 09:05:14PM +0200, Manuel Bouyer wrote:
> > On Tue, Apr 26, 2011 at 11:52:00AM -0700, Garrett Cooper wrote:
> > > [...]
> > > I've been watching this discussion and one hing i was curious about was 
> > > -- is it widely known that there are a handful of ATA <-> SCSI specs that 
> > > have been released by IEEE over the past decade. I figured someone was 
> > > aware of this on the list, but was kind of puzzled by the replies about 
> > > FreeBSD, Linux and windows behavior when in fact the behavior is allowed 
> > > and standard.
> > 
> > Can you gives pointers about this ? AFAIK ata is still something
> > different from SAM or SPC.
> 
> T10 has a "SCSI / ATA Translation (SAT)" standard.
> It covers how to translate/encapsulate ATA commands for SCSI.
> It's often implemented in many newer USB Mass Storage Class SATA bridges.

OK, I found it. As I see it it's more for things like SATA to USB or
SATA to SAS bridges, than something we want to emulate in the host's
drivers. An extra emulation/translation layer is not desireable here.

We may want to implement some of the SAT-specific commands in our
sd(4) and/or cd(4) to have access to more details of the underlying device
(e.g. setup power management modes).

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--