Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754726AbZG1QCk (ORCPT ); Tue, 28 Jul 2009 12:02:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754702AbZG1QCj (ORCPT ); Tue, 28 Jul 2009 12:02:39 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:44777 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754629AbZG1QCi (ORCPT ); Tue, 28 Jul 2009 12:02:38 -0400 Date: Tue, 28 Jul 2009 09:00:49 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Alan Cox cc: Zachary Amsden , Tejun Heo , Peter Zijlstra , linux-kernel@vger.kernel.org, axboe@kernel.dk, hch@infradead.org, akpm@linux-foundation.org, Paul.Clements@steeleye.com, tytso@mit.edu, miklos Subject: Re: [PATCH] Allow userspace block device implementation In-Reply-To: <20090728112734.5a75752d@lxorguk.ukuu.org.uk> Message-ID: References: <4A6D79F6.3050509@redhat.com> <1248699365.6987.1628.camel@twins> <20090727142536.465799aa@lxorguk.ukuu.org.uk> <4A6E529B.9030104@kernel.org> <4A6E764E.80805@redhat.com> <20090728112734.5a75752d@lxorguk.ukuu.org.uk> User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1884 Lines: 41 On Tue, 28 Jul 2009, Alan Cox wrote: > > Use device mapper. Really we should shoot all the partition code in the > kernel but the back compatibility is a bit tricky. We don't actually need > the partition code any more. Really, we should _not_ "shoot all the partition code in the kernel". Quite the reverse. You need the kernel to read the disk anyway, you're _much_ better off having the kernel know about the partitioning etc. There are absolutely zero upsides to making the bootup be dependent on yet another user land tool, and then effectively forcing people to use initrd whether they want it or not - just in order to find the real root. The fact that some distributions already go too far, and use DM whether it makes sense or not is only inconveniencing real users. It makes things like data portability much harder. I have had real-life cases where I wanted to move a disk from one machine to another, only to notice that the crazy default for the distro I had used was to make it impossible, because all the filesystems crossed disks. I've since learnt to not use DM (and instead doing a very inconvenient "partition everything by hand because the install tool doesn't allow for any simple automated way to make a sane install"), and to just put /home on one disk and / on the other, and then I can way more easily just move my /home disk around, for example. Yes, I realize that MD is convenient for a certain class of users, but a _lot_ of distro people seem to totally miss all the inconveniences. Possibly because they care more about "enterprise" customers than about people who tinker. Linus -- 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/