From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 17 Jun 2002 01:20:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 17 Jun 2002 01:20:14 -0400 Received: from mailout05.sul.t-online.com ([194.25.134.82]:43239 "EHLO mailout05.sul.t-online.com") by vger.kernel.org with ESMTP id convert rfc822-to-8bit; Mon, 17 Jun 2002 01:20:12 -0400 Content-Type: text/plain; charset=US-ASCII From: Oliver Neukum To: James Bottomley Subject: Re: [linux-usb-devel] Re: /proc/scsi/map Date: Mon, 17 Jun 2002 07:19:52 +0200 User-Agent: KMail/1.4.1 Cc: James Bottomley , David Brownell , Andries.Brouwer@cwi.nl, garloff@suse.de, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, sancho@dauskardt.de, linux-usb-devel@lists.sourceforge.net, linux1394-devel@lists.sourceforge.net, dougg@torque.net References: <200206162314.g5GNEYf03058@localhost.localdomain> In-Reply-To: <200206162314.g5GNEYf03058@localhost.localdomain> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: <200206170719.52136.oliver@neukum.name> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Am Montag, 17. Juni 2002 01:14 schrieb James Bottomley: > oliver@neukum.name said: > > But the drivers already know, or would have to be taught to know about > > it. Somewhence that information has to come. You cannot avoid that > > effort. > > Not necessarily: consider the SCSI WWN, which is supported by most > modern SCSI devices. The driver never probes for or asks for this. > Nowhere in the current SCSI code do we ask for this. However user level > commands (like sg_inq) can formulate the 0x83 page inquiry to get this > and return the output. This works today with the current driver. These may be an exception. You usually want to get drivers involved even if only for synchronisation. Failing to do so has already let to problems with usb storage. > > That is wrong. You'd need a common method to determine device type and > > several methods of passing guid. You are better off in implementing > > one common way of getting at that information, which shouldn't be too > > hard, as all the generic layer would have to do is pass up that > > information. > > but the complexity is in the "common method to determine device type and > several methods of passing guid". Even for a simple SCSI disk, there's > no one universal way of getting a unique id (let alone when we add the > usb devices masquerading as scsi disks into the mix). That will lead us That is the point. The driver knows best what kind of devices it works on. You can forget about the whole identification method business, if you go for the driver. In case of usb storage and firewire that data is already sitting there ready for taking. I suspect the same for fibrechannel. Regards Oliver