From owner-freebsd-current Wed Aug 21 10:27:15 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3CF7037B400; Wed, 21 Aug 2002 10:27:10 -0700 (PDT) Received: from duey.wolves.k12.mo.us (duey.wolves.k12.mo.us [207.160.214.9]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7F9D743E4A; Wed, 21 Aug 2002 10:27:09 -0700 (PDT) (envelope-from cdillon@wolves.k12.mo.us) Received: from duey.wolves.k12.mo.us (cdillon@localhost [127.0.0.1]) by duey.wolves.k12.mo.us (8.12.5/8.12.5) with ESMTP id g7LHR1sd094791; Wed, 21 Aug 2002 12:27:01 -0500 (CDT) (envelope-from cdillon@wolves.k12.mo.us) Received: from localhost (cdillon@localhost) by duey.wolves.k12.mo.us (8.12.5/8.12.5/Submit) with ESMTP id g7LHR0fk094788; Wed, 21 Aug 2002 12:27:00 -0500 (CDT) X-Authentication-Warning: duey.wolves.k12.mo.us: cdillon owned process doing -bs Date: Wed, 21 Aug 2002 12:27:00 -0500 (CDT) From: Chris Dillon To: Terry Lambert Cc: "Kenneth D. Merry" , Thomas Quinot , Nate Lawson , , Subject: Re: Proliferating quirk table entries In-Reply-To: <3D632D84.1CDEAD3@mindspring.com> Message-ID: <20020821121019.P93963-100000@duey.wolves.k12.mo.us> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Tue, 20 Aug 2002, Terry Lambert wrote: > I think everyone in this thread needs to read the last instance of > this same thread, the first time it came up. > > I believe the general consensus was to send the 6, and if it failed, > retry with the 10, and set a flag so that subsequent requests were > 10 (this instead of a static quirk table that could find itself out > of date). As someone mentioned, some devices choke on the first 6-byte command and then just don't work anymore even if you start sending the 10-byte commands from then on. I have a USB multi-flash (CF/MD, MMC, SD, etc) card reader that does exactly that. I have to enable "kern.cam.da.no_6_byte=1" before try to use the device and everything works fine. I also don't have any problems with any of my other SCSI devices (various SCSI CD-ROMs, a SCSI CD-RW, a SCSI ZIP drive, and SCSI DDS2 and DDS3 tape drives) when using only 10-byte commands. What problems would occur if you try 10 first and then 6 if that fails? Will the devices that only take 6-byte commands choke permanently on the first 10-byte command as some of the non-SCSI stuff does on the 6-byte commands, or would they truncate 4 bytes and treat it as the wrong command? I believe someone already proposed this, but since only some very old SCSI devices won't handle 10-byte commands correctly (correct me if I'm wrong there) and should affect very few people, how about just enabling 10-byte commands by default and offering a sysctl to turn on the 6-byte-then-10-byte method when it is needed? The benefit of that should greatly outweigh the drawbacks with the state of the hardware as it is today. -- Chris Dillon - cdillon(at)wolves.k12.mo.us FreeBSD: The fastest and most stable server OS on the planet - Available for IA32 (Intel x86) and Alpha architectures - IA64, PowerPC, UltraSPARC, ARM, and S/390 under development - http://www.freebsd.org No trees were harmed in the composition of this message, although some electrons were mildly inconvenienced. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message