From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266036AbUBJTYf (ORCPT ); Tue, 10 Feb 2004 14:24:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266131AbUBJTYf (ORCPT ); Tue, 10 Feb 2004 14:24:35 -0500 Received: from h24-82-88-106.vf.shawcable.net ([24.82.88.106]:2189 "HELO tinyvaio.nome.ca") by vger.kernel.org with SMTP id S266036AbUBJTYa (ORCPT ); Tue, 10 Feb 2004 14:24:30 -0500 Date: Tue, 10 Feb 2004 11:24:57 -0800 From: Mike Bell To: Chris Friesen Cc: Greg KH , linux-kernel@vger.kernel.org Subject: Re: devfs vs udev, thoughts from a devfs user Message-ID: <20040210192456.GB4814@tinyvaio.nome.ca> References: <20040210113417.GD4421@tinyvaio.nome.ca> <20040210170157.GA27421@kroah.com> <20040210171337.GK4421@tinyvaio.nome.ca> <40291A73.7050503@nortelnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <40291A73.7050503@nortelnetworks.com> User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 10, 2004 at 12:52:51PM -0500, Chris Friesen wrote: > What names would you use for your device files? This is the key > difference. With udev it gets a notification that says "I have a new > block device", it then looks it up, applies the rules, and creates a new > entry. The whole point is to move the naming scheme into userspace for > easier management. Why does it make management easier to have no predictable name for a device? > You could have the kernel export a simple devfs with a hardcoded naming > scheme based on similar ideas as what is in sysfs (which would then make > sysfs and the daemon optional for tiny embedded setups), but the only > advantage over just exporting the information in sysfs is to save a few > bytes at the cost of yet another filesystem to maintain. I think the space savings are a pretty good reason alone. Add to that the fact I think devfs would be a good idea even if it cost MORE memory... You can mount a devfs on your RO root instead of needing to mount a tmpfs on /dev and then run udev on that. A devfs gives consistant names for devices in addition to the user's preferred user-space dictated naming scheme. A devfs means even with dynamic majors/minors, even if you have new hardware in your system, your /dev at least has the devices it needs.