From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756193Ab1FQDdP (ORCPT ); Thu, 16 Jun 2011 23:33:15 -0400 Received: from mail7.hitachi.co.jp ([133.145.228.42]:38518 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755399Ab1FQDdO (ORCPT ); Thu, 16 Jun 2011 23:33:14 -0400 X-AuditID: b753bd60-a46b0ba0000019f4-0a-4dfacaf7c33e X-AuditID: b753bd60-a46b0ba0000019f4-0a-4dfacaf7c33e Message-ID: <4DFACAF1.3010300@hitachi.com> Date: Fri, 17 Jun 2011 12:33:05 +0900 From: Masami Hiramatsu Organization: Systems Development Lab., Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; ja; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10 MIME-Version: 1.0 To: Greg KH Cc: James Bottomley , Nao Nishijima , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, kay.sievers@vrfy.org, jcm@redhat.com, hare@suse.de, stefanr@s5r6.in-berlin.de, yrl.pp-manager.tt@hitachi.com Subject: Re: [PATCH 1/3] [RFC] genhd: add a new attribute in device structure References: <20110615081610.2237.44767.stgit@ltc233.sdl.hitachi.co.jp> <20110615081627.2237.9620.stgit@ltc233.sdl.hitachi.co.jp> <20110615153337.GA10160@kroah.com> <4DF9F11F.705@hitachi.com> <20110616154129.GA31498@kroah.com> <1308239454.2436.34.camel@mulgrave> <20110616161442.GA32113@kroah.com> In-Reply-To: <20110616161442.GA32113@kroah.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2011/06/17 1:14), Greg KH wrote: > On Thu, Jun 16, 2011 at 11:50:54AM -0400, James Bottomley wrote: >>> And again, why not just fix the userspace tools? That is trivial to do >>> so and again, could have been done by now in the years this has been >>> discussed. >> >> So I can summarise where I think we are in these discussions: >> >> We provide the ability to give all kernel devices a "preferred name". >> By default this will be the device name the kernel would have originally >> assigned. the dev_printk's will use the preferred name, and it will be >> modifiable from user space. All the kernel will do is print out >> whatever it is ... no guarantees of uniqueness or specific format will >> be made. Since we're only providing one preferred_name file, the kernel >> can only have one preferred name for a device at any given time >> (although it is modifiable on the fly as many times as the user >> chooses). >> >> The design is to use this preferred name to implement what Hitachi wants >> in terms of persistent name, but we don't really care. >> >> All userspace naming will be taken care of by the usual udev rules, so >> for disks, something like /dev/disk/by-preferred/ which would be >> the usual symbolic link. > > No, udev can not create such a link after the preferred name is set, as > it has no way of knowing that the name was set. > >> This will ensure that kernel output and udev input are consistent. It >> will still require that user space utilities which derive a name for a >> device will need modifying to print out the preferred name. > > It also doesn't solve the issue of userspace wanting to use such a > "preferred" name in the command line of tools, as there will not be a > link back to the "kernel" name directly in /dev/. Right, this series just add a preferred name interface, and changes a part of kernel messages. > So as userspace tools will still need to be fixed, I don't see how > adding a kernel file for this is going to help any. Well, a bit in that > the kernel log files will look "different", but again, that really isn't > a problem that userspace couldn't also solve with no kernel changes > needed. hmm, He didnt say "this can solve all problems". I think preferred name is just a starting point to solve these problems. Actually, he decided to fix those user space tools to accept persistent symbolic links, and to show it in outputs. It's not complete, but a good starting point, isn't it? Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com