Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263812AbTE0P1j (ORCPT ); Tue, 27 May 2003 11:27:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263894AbTE0P0Z (ORCPT ); Tue, 27 May 2003 11:26:25 -0400 Received: from nat9.steeleye.com ([65.114.3.137]:29958 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S263867AbTE0PZk (ORCPT ); Tue, 27 May 2003 11:25:40 -0400 Subject: Re: [BK PATCHES] add ata scsi driver From: James Bottomley To: Jeff Garzik Cc: Linus Torvalds , Jens Axboe , Linux Kernel In-Reply-To: <20030527152113.GA21744@gtf.org> References: <1054047595.1975.64.camel@mulgrave> <20030527152113.GA21744@gtf.org> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.8 (1.0.8-9) Date: 27 May 2003 11:38:50 -0400 Message-Id: <1054049931.1975.129.camel@mulgrave> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1477 Lines: 35 On Tue, 2003-05-27 at 11:21, Jeff Garzik wrote: > ATA defines WWN too... I'm curious what the format is? uuid-ish? Heh, you'll regret asking that one. There are currently seven possible identifier formats for the WWN (which is basically the SCSI Device Identification VPD page). The extremely gory details are in the SPC-3 spec (section 7.6.4 of r12). However, really, as far as Linux is concerned we don't need to care. It just needs to be reducible to an ASCII representation and dumped into the sysfs name or embedded into bus_id. The reduction to ASCII can be subsystem (or even device driver) specific. However, note that I'm not thinking of forcing the WWN here. I'm thinking of using whatever makes most sense to the device, so SPI devices will continue to use simple target/lun numbers here. FC devices will probably want to use their variant of WWN/PortID. The rationale is to get rid of the unnecessary internal mappings some drivers use to get to the physical address they send on the wire. Thus, if you never address ATA devices by the WWN, you probably never want to make it part of the addressing scheme. Exporting a unique ID for userspace to use is a different (and probably orthogonal) issue. James - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/