From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265648AbTLIHkM (ORCPT ); Tue, 9 Dec 2003 02:40:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265649AbTLIHkM (ORCPT ); Tue, 9 Dec 2003 02:40:12 -0500 Received: from mhub-w5.tc.umn.edu ([160.94.160.35]:6109 "EHLO mhub-w5.tc.umn.edu") by vger.kernel.org with ESMTP id S265648AbTLIHkF (ORCPT ); Tue, 9 Dec 2003 02:40:05 -0500 Subject: Re: udev sysfs docs Re: State of devfs in 2.6? From: Matthew Reppert To: Bob Cc: linux-kernel , witukind@nsbm.kicks-ass.org In-Reply-To: <3FD577E7.9040809@nishanet.com> References: <200312081536.26022.andrew@walrond.org> <20031208154256.GV19856@holomorphy.com> <3FD4CC7B.8050107@nishanet.com> <20031208233755.GC31370@kroah.com> <20031209061728.28bfaf0f.witukind@nsbm.kicks-ass.org> <3FD577E7.9040809@nishanet.com> Content-Type: text/plain Message-Id: <1070955596.25311.19.camel@minerva> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 Date: Tue, 09 Dec 2003 01:39:56 -0600 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2003-12-09 at 01:21, Bob wrote: > Witukind wrote: > > >From the udev FAQ: > > > >Q: But udev will not automatically load a driver if a /dev node is opened > > when it is not present like devfs will do. > >A: If you really require this functionality, then use devfs. It is still > > present in the kernel. > > > >Will it have this 'equivalent functionality' some day? > > > > > > > > > Shouldn't hotplug handle it? How would hotplug handle it? Or, more directly ... on my system, /dev is just a normal directory on an ext2 filesystem. If something tries to open a file on it that doesn't exist, open will just return ENOENT. How is open supposed to know that someone is trying to open a device node? The naive solution is to conditionally check for the presence of "/dev" at the beginning of all requested filenames that don't exist, which strikes me as ... well, not necessarily a good idea. (I can't really say why beyond gut feeling.) My guess is, unfortunately, udev probably won't handle this any time soon. (Or, if it does, through some possibly clever mechanism that, as someone unfamiliar with the relevant bits of the system, I can't see.) I'd be interested in a solution to this, mostly out of curiosity since it seems like it might be interesting, but I don't see a nice one coming easily. I wouldn't mind someone more clueful telling me I'm wrong, though. At the least, it means more people being receptive to moving to udev. Matt