From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <9d952cfbeb395cbf4fb966ff2653a6b8@coraid.com> To: 9fans@cse.psu.edu Subject: Re: [9fans] page fault with lock held From: Brantley Coile Date: Wed, 13 Apr 2005 09:20:41 -0400 In-Reply-To: <200504131313.j3DDDhJ16603@augusta.math.psu.edu> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="upas-ukjnwfqqgylxbejowdqlpasmvh" Topicbox-Message-UUID: 3765856e-ead0-11e9-9d60-3106f5b1d025 This is a multi-part message in MIME format. --upas-ukjnwfqqgylxbejowdqlpasmvh Content-Disposition: inline Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit ATA has a common and squalid past. ATAPI is a packet interface layed on top of ATA to pass SCSI commands to things like CDROMs, but ATA as such has it's own protocol. ATA started out as a chip from Western Digitial, the WD1010. This ST506 disk controller was used in XT and AT PC. When the silicon could support it, the functions were moved into the devices and all that was left was the interface to the 1010. Logical block addresses have replaced the cyl, head, sector, but much of the interface is the same as the one I was programming in 1983. DMA speeds are faster, things like S.M.A.R.T. allow watching for errors on drives, and now we even have command queueing, but mostly it's the same stuff. I like the idea of having a way to hook into the bottom of sd from user land! Brantley --upas-ukjnwfqqgylxbejowdqlpasmvh Content-Type: message/rfc822 Content-Disposition: inline Received: from mail.cse.psu.edu ([130.203.4.6]) by coraid.com; Wed Apr 13 09:14:13 EDT 2005 Received: from psuvax1.cse.psu.edu (localhost [127.0.0.1]) by mail.cse.psu.edu (CSE Mail Server) with ESMTP id 3AFE619141 for ; Wed, 13 Apr 2005 09:14:04 -0400 (EDT) X-Original-To: 9fans@cse.psu.edu Delivered-To: 9fans@cse.psu.edu Received: from localhost (localhost [127.0.0.1]) by mail.cse.psu.edu (CSE Mail Server) with ESMTP id D774F19001 for <9fans@cse.psu.edu>; Wed, 13 Apr 2005 09:13:46 -0400 (EDT) Received: from mail.cse.psu.edu ([127.0.0.1]) by localhost (psuvax1 [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 27999-01-20 for <9fans@cse.psu.edu>; Wed, 13 Apr 2005 09:13:43 -0400 (EDT) Received: from math.psu.edu (leibniz.math.psu.edu [146.186.130.2]) by mail.cse.psu.edu (CSE Mail Server) with ESMTP id D1E3118FF6 for <9fans@cse.psu.edu>; Wed, 13 Apr 2005 09:13:43 -0400 (EDT) Received: from augusta.math.psu.edu (augusta.math.psu.edu [146.186.132.2]) by math.psu.edu (8.11.7p1+Sun/8.12.10) with ESMTP id j3DDDh510825 for <9fans@cse.psu.edu>; Wed, 13 Apr 2005 09:13:43 -0400 (EDT) Received: from augusta.math.psu.edu (localhost [127.0.0.1]) by augusta.math.psu.edu (8.11.6+Sun/8.9.3) with ESMTP id j3DDDhJ16603 for <9fans@cse.psu.edu>; Wed, 13 Apr 2005 09:13:43 -0400 (EDT) Message-Id: <200504131313.j3DDDhJ16603@augusta.math.psu.edu> To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu> Subject: Re: [9fans] page fault with lock held In-Reply-To: Your message of "Tue, 12 Apr 2005 16:58:44 EDT." Date: Wed, 13 Apr 2005 09:13:43 -0400 From: Dan Cross X-Virus-Scanned: by amavisd-new at cse.psu.edu X-BeenThere: 9fans@cse.psu.edu X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu> List-Id: Fans of the OS Plan 9 from Bell Labs <9fans.cse.psu.edu> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: 9fans-bounces+brantley=coraid.com@cse.psu.edu Errors-To: 9fans-bounces+brantley=coraid.com@cse.psu.edu Russ Cox writes: > > > I had wanted to see an sdloopback device (devsdloop was I suppose > > what I called it) that could speak SCSI to a file descriptor that > > could come from anywhere. Then things like this might not need to > > be in the kernel at all. > > sd has little to do with scsi. > in particular, these devices don't speak scsi. Maybe I'm confused; it's been a while. I thought that AoE was ATA over Ethernet or something like that, and that ATA was basically the SCSI protocol over different electronics. I was originally looking at this in terms of a digital camera that connected via USB, which did speak SCSI. Regardless, the salient point was that there should some way to hook into the devsd framework from userland. - Dan C. --upas-ukjnwfqqgylxbejowdqlpasmvh--