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Date:      Mon, 12 May 2008 10:14:33 +0400
From:      "Andrey V. Elsukov" <bu7cher@yandex.ru>
To:        Jeremy Chadwick <koitsu@freebsd.org>
Cc:        stable@freebsd.org, jonathan@kc8onw.net, sos@FreeBSD.org
Subject:   Re: ATA APM and NCQ support in FreeBSD atacontrol
Message-ID:  <4827E049.4030500@yandex.ru>
In-Reply-To: <20080512060938.GA2007@eos.sc1.parodius.com>
References:  <29626.214.13.212.30.1210554531.squirrel@www.kc8onw.net> <20080512030647.GA93725@eos.sc1.parodius.com> <4827D531.7000603@yandex.ru> <20080512060938.GA2007@eos.sc1.parodius.com>

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Jeremy Chadwick wrote:
>> No. ata(4) driver currently doesn't support/use NCQ.
> 
> Thanks for this information -- I had no idea!  I'll add this to my
> Common Issues page, although it's not so much an "issue" but more so a
> feature.
> 
> I was always under the impression that AHCI included automatic support
> for negotiation and use of extensions like NCQ and TCQ:
> 
> http://en.wikipedia.org/wiki/Native_Command_Queuing
> http://www.seagate.com/content/docs/pdf/whitepaper/D2c_tech_paper_intc-stx_sata_ncq.pdf

AHCI has standart method to determine presence of NCQ support.
But FreeBSD's driver needs some code to work with NCQ.
Soren said to me that he is going to work with NCQ support
after merging PM support, but I don't know about current status.

-- 
WBR, Andrey V. Elsukov



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