From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH] remove ide-scsi Date: Sun, 07 Dec 2008 18:21:10 +0300 Message-ID: <493BE9E6.7050802@ru.mvista.com> References: <20081203103856S.fujita.tomonori@lab.ntt.co.jp> <200812061551.08525.bzolnier@gmail.com> <20081206120001.3580b9e3@tuna> <200812062241.35601.bzolnier@gmail.com> <20081206222423.04aada70@lxorguk.ukuu.org.uk> <493B022B.3050406@ru.mvista.com> <20081206230227.07b00e2f@lxorguk.ukuu.org.uk> <493B0867.5020700@ru.mvista.com> <1228662298.3501.19.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1228662298.3501.19.camel@localhost.localdomain> Sender: linux-scsi-owner@vger.kernel.org To: James Bottomley Cc: Alan Cox , Bartlomiej Zolnierkiewicz , =?ISO-8859-1?Q?Dan_No=E9?= , Christoph Hellwig , FUJITA Tomonori , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, osst@riede.org List-Id: linux-ide@vger.kernel.org Hello. James Bottomley wrote: >>>> Oh, yes. SCSI emulation is just what Linux embedded world is asking >>>> for... >>>> >>>> >>> Well ATAPI is SCSI emulation (its a sort of pidgin SCSI admittedly). >>> >>> >> ATAPI is SCSI transport (with maybe some quirks at SCSI command level >> tho, IIRC). ATA is neither thansport nor does it map to SCSI 1:1. >> > > > Well, to be wholly accurate, since SCSI-3, SCSI has been separated into > an architecture, primary command, device specific command and transport > model (called the SCSI architecture model). Thanks, I'm well aware of all this. :-) My first encounter with SCSI dates back to 1993-94 -- it's a pity that I had to abandon this area (switching to that puny IDE ;-)... > Starting with ATA-8, ATA > will go this way again. It's gone that way in ATA/PI-7 actually, being broken into 3 separate documents then, one spoecifying the command set and 2 others PATA and SATA tranports. > What ATAPI actually is is a SCSI (really MMC > for CD and SSC for tape) Unfortunately, the initial SFF documents specified both the transport protocol and the command sets (which somewhat diverged form what SCSI-2 had, IIRC). Fortunately, once ANSI finally taken over ATAPI work, they dropped that stupid practice and started referring to MMC and SSC. > command transported over ATA using the ATA > PACKET command. With ATA-8 it will be much more analogous to SCSI > command over ATA transport. > I don't think "analogous" means that it will be sending SCSI CDBs over PATA/SATA is of native commands and turn ATA into ATAPI. So all this is fine but changes nothing about the SCSI emulation thing. >> The code for emulating SCSI on ATA only burdens the kernel (and causes user >> complaints about changing disk names from /dev/hdx to /dev/sda :-). >> > > The code for sorting this out is already upstream in the block tree for > 2.6.29. > Sorting out what, emulation? I have to cut my response short that that point. I must be totally crazy to allow myself to be dragged into this discussion having so much work to do... :-/ MBR, Sergei