From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753968AbZEIQXV (ORCPT ); Sat, 9 May 2009 12:23:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751595AbZEIQXM (ORCPT ); Sat, 9 May 2009 12:23:12 -0400 Received: from cantor.suse.de ([195.135.220.2]:59338 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751440AbZEIQXM (ORCPT ); Sat, 9 May 2009 12:23:12 -0400 Date: Sat, 9 May 2009 09:19:23 -0700 From: Greg KH To: Arjan van de Ven Cc: Fabio Comolli , Greg KH , linux-kernel@vger.kernel.org Subject: Re: [patch 00/13] devtmpfs patches Message-ID: <20090509161923.GA942@suse.de> References: <20090509143742.GA27663@kroah.com> <20090509150853.GA32394@suse.de> <20090509082233.32cbb8e4@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090509082233.32cbb8e4@infradead.org> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 09, 2009 at 08:22:33AM -0700, Arjan van de Ven wrote: > On Sat, 9 May 2009 08:08:53 -0700 > Greg KH wrote: > > > > Well, guess you meant the opposite ;-) > > > > Heh, yes, sorry about that. It makes booting faster :) > > .. and I don't buy that. Kay posted numbers showing this. I have bootchart graphics somewhere around here that also shows this. > The only argument I've heard is "oh but it's hard". No it's not. No, it's not "hard", it's just reality :) > The other argument is "but for more partitions we get other device > numbers"... you know what, that's easy to fix. Just make the 32 bit dev > number consistent. Few lines of code I bet, and it is benefit for > everyone to do that.... Huh? We need to be able to support large number of partitions at boot time. We also need to support an initrd, and not a static /dev/ tree at boot time, as that is what the world requires from a flexible Linux distro that runs on multiple types of hardware configurations. Sure, if you can ensure your hardware platform isn't going to change, and is relativly limited (as Moblin currently does), then you don't need an initrd and you can get away with a static /dev and save a few hundred's of a second. But the distros can't do that, they are stuck supporting users with tens of partitions and other "wierd" configurations. > Beyond that... this is not needed... but at least call it "devfs".. for > what it is. It's not a stand-alone filesystem. It's an in-kernel mknod on top of tmpfs. Heck, if it's just a matter of the name change, I'll gladly do it. That doesn't stop the fact that it's still a very useful and needed option for lots of configurations where Linux is used (embedded, rescue disks, fast boot on flexable distros, etc.) > (and yes there is very obvious irony) devfs was removed for a number of other reasons (bad code, maintainer left, in-kernel policy that was in contrast to the LSB, modprobe from within the kernel, thousands of lines of code, etc.) Turns out that the idea of a devfs is a good one, and here is a simple, and easy to understand and maintain implementation of such a thing. I'll be the first to say this, hence it is without irony that I am proposing it be included. If there are any technical problems with the proposed patches, please let us know. thanks, greg k-h