From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 16 May 2001 19:56:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 16 May 2001 19:56:04 -0400 Received: from neon-gw.transmeta.com ([209.10.217.66]:49669 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id ; Wed, 16 May 2001 19:55:48 -0400 Message-ID: <3B03137A.80221C59@transmeta.com> Date: Wed, 16 May 2001 16:55:38 -0700 From: "H. Peter Anvin" Organization: Transmeta Corporation X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.5-pre1-zisofs i686) X-Accept-Language: en, sv, no, da, es, fr, ja MIME-Version: 1.0 To: Richard Gooch CC: Linux Kernel Mailing List Subject: Re: LANANA: To Pending Device Number Registrants In-Reply-To: <200105152141.f4FLff300686@vindaloo.ras.ucalgary.ca> <200105161822.f4GIMo509185@vindaloo.ras.ucalgary.ca> <3B02D6AB.E381D317@transmeta.com> <200105162001.f4GK18X10128@vindaloo.ras.ucalgary.ca> <3B02DD79.7B840A5B@transmeta.com> <200105162054.f4GKsaF10834@vindaloo.ras.ucalgary.ca> <3B02F2EC.F189923@transmeta.com> <20010517001155.H806@nightmaster.csn.tu-chemnitz.de> <3B02FBA6.86969BDE@transmeta.com> <200105162303.f4GN3n212178@vindaloo.ras.ucalgary.ca> <3B030C76.40BB4558@transmeta.com> <200105162337.f4GNb0j12743@vindaloo.ras.ucalgary.ca> <3B030F86.EDA45D1A@transmeta.com> <200105162341.f4GNfvT12861@vindaloo.ras.ucalgary.ca> <3B0310A4.87138FB5@transmeta.com> <200105162349.f4GNnSJ13049@vindaloo.ras.ucalgary.ca> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Richard Gooch wrote: > > OK. How do you figure on dealing with the problem of multiple > high-level drivers talking to the same device? How does sr.o "know" > that this is also a CD-RW? How does sg.o "know" that this is also a > tape? > At some point something talks to the device -- in this case, it's the SCSI layer. Follow the interfaces in the kernel and it becomes obvious. > Where does the responsibility lie for figuring out the capabilities? > > Further, which device node/fs/driver exports the capability list? > > And what about locking between drivers? Orthogonal issue. You may want a locking mechanism, but it almost certainly should not be automatic. Note that especially ide-scsi is a good example on how *not* to do things. The fact that you have to choose one of two interfaces for different operations (I can't use a CD-writer in the default configuration!) is insane. -hpa -- at work, in private! "Unix gives you enough rope to shoot yourself in the foot." http://www.zytor.com/~hpa/puzzle.txt