Re: Thinking about NCQ support for NetBSD

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

On Tue, May 21, 2013 at 11:14:03PM -0700, Brian Buhrow wrote:
>       hello.  Recently I've been working on some fixes for the mpt(4)
> driver.  In the process of getting those fixes working, I began thinking
> about how hard it would be to get NCQ tag queueing working for NetBSD.  In
> the process of getting my head around what is involved, I find I have
> questions.  If someone wants to share what they know here or privately,
> I'd be interested in reading.
> 
> 1.  I read a document that discussed ahcisata and its advantages over
> traditional IDE mode.  One of the advantages it touted was that ahcisata
> would support NCQ tag queueing.  Is it a requirement in order for NCQ
> tag queueing to work that the interface card support it as well?  For
> example, the viaide(4) driver supports SATA controllers, but says nothing
> about NCQ support or the potential for it.

Support on the controller side is needed AFAIK. controllers exposing
only the pciide registers probably can't support NCQ at all.
For NCQ to be used in an efficient way, a smart controller is probably
requireed.


> 
> 2.  Does anyone have any preliminary patches for NCQ support that the never
> got into the system?

AFAIK no. 

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