From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261792AbVGaOCA (ORCPT ); Sun, 31 Jul 2005 10:02:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263227AbVGaOCA (ORCPT ); Sun, 31 Jul 2005 10:02:00 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:23988 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S261792AbVGaOB6 (ORCPT ); Sun, 31 Jul 2005 10:01:58 -0400 Date: Sun, 31 Jul 2005 15:01:57 +0100 From: Christoph Hellwig To: Thomas Heinz Cc: linux-kernel@vger.kernel.org Subject: Re: SCSI DVD-RAM partitions Message-ID: <20050731140157.GA6173@infradead.org> Mail-Followup-To: Christoph Hellwig , Thomas Heinz , linux-kernel@vger.kernel.org References: <42CFC3EF.2090804@gmx.net> <20050712023757.GG26128@infradead.org> <42D37DF5.6060902@gmx.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42D37DF5.6060902@gmx.net> User-Agent: Mutt/1.4.2.1i X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 12, 2005 at 10:23:17AM +0200, Thomas Heinz wrote: > Hi Christoph > > You wrote: > >While adding support for partitions on sr is trivial it has a huge > >drawback: it's chaning the dev_t space by using up device numbers > >for partitions, so /dev/sr0 ff will have different device numbers > >with that change applied. I have an old patch that's supposed to > >enable support for partitioned scsi removable devices at > >http://rechner.lst.de/~hch/hacks/sr-parts.diff, I'm not sure it > >actually ever worked (but you should get the basic idea from it) > > Ok, thanks for your valuable input. In fact, I thought about making > the device available both as /dev/srX and /dev/sdX at the same time > in order to support partitions. In my case it would even suffice to > make it available as /dev/sdX instead of /dev/srX. That doesn't make sense because sd is a very different driver from sd. Besides that aliasing different dev_ts to the same underlying blockdevice can't work, it's cause all sorts of aliasing problems. > Since I have no expert knowledge about this topic, I would be > interested in the general attitude towards "partitions on SCSI > DVD-RAM media / SCSI removable devices": > - Are partitions intentionally not supported? If so, why? Historical coincidence. > - Does it usually work but not with my specific DVD-RAM model? > If so, why? > - Do you think that this should be fixed? There's no nice way to fix it unfortunately. > Please note that personally, I can live with the "losetup hack" > since it is easy enough to write a program which encapsulates > partition mounting. However, there might be people which would > prefer plugging in a (possibly pre-)partitioned medium and > having the partitions work out of the box in the expected way. It would probably be better to use device-mapper than the loop device. I think there's already userland partition parsing code for dm, and having a simple command line tool to do that, and maybe even automatically run through udev and creating /dev/srp devices would be very nice to have as an almost invisible workaround.