From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263850AbUAEEie (ORCPT ); Sun, 4 Jan 2004 23:38:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264387AbUAEEie (ORCPT ); Sun, 4 Jan 2004 23:38:34 -0500 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:29340 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S263850AbUAEEib (ORCPT ); Sun, 4 Jan 2004 23:38:31 -0500 Date: Mon, 5 Jan 2004 04:38:30 +0000 From: viro@parcelfarce.linux.theplanet.co.uk To: Linus Torvalds Cc: Daniel Jacobowitz , Andries Brouwer , Rob Love , rob@landley.net, Pascal Schmidt , linux-kernel@vger.kernel.org, Greg KH Subject: Re: udev and devfs - The final word Message-ID: <20040105043830.GE4176@parcelfarce.linux.theplanet.co.uk> References: <20040104034934.A3669@pclin040.win.tue.nl> <20040104142111.A11279@pclin040.win.tue.nl> <20040104230104.A11439@pclin040.win.tue.nl> <20040105030737.GA29964@nevyn.them.org> <20040105035037.GD4176@parcelfarce.linux.theplanet.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 04, 2004 at 08:02:20PM -0800, Linus Torvalds wrote: > > > On Mon, 5 Jan 2004 viro@parcelfarce.linux.theplanet.co.uk wrote: > > > > What is _not_ OK, though, is to have folks suddenly see /dev/hda3 changing > > its device number - then we would break existing setups that worked all > > along; even if admin can fix the breakage, it's not a good thing to do. > > Ehh, it will actually happen. > > If nothing else, things like SATA will end up meaning that the device you > were used to seeign as /dev/hdc will suddenly show up as /dev/scd0 > instead. Just because you changed the cabling while you upgraded to a > newer version of your CD-ROM drive. If I open the damn box, I sure as hell can be bothered to edit stuff in /etc... > And the thing is, with fs labels and udev, even "existing systems" really > shouldn't much care. > > Now, we'd probably not want to force the switch, but I do suspect we'll > have exactly this as a switch in the "Kernel Debugging Config" section. > Where even _common_ things like disks could end up with per-bootup values. > Just to verify that every part of the system ends up having it right. Then we'd better have a very good idea of the things that are going to break. Note that right now even late-boot code in kernel itself will break on that - there are explicit checks for ROOT_DEV==MKDEV(2,0), all sorts of weird crap deep in the bowels of arch/ppc/*/*, etc. It won't be an easy transition - I know that Greg is very optimistic about it, but there will be a *lot* of crap to take care of. In theory getting bigger dev_t should've been very straightforward, but if you check what really had been involved... ObOtherStraightforwardThings: net_device refcounting. Take a look at Jeff's queue someday - by now it's one big merge short of getting it right for practically all drivers. 1.9Mb total + 247Kb pending patches here. Several hundreds changesets, practically all of them fixing exploitable holes. And yes, most of them had been bugs all along - since 2.2 if not earlier. Sure, that made things better, but if somebody comes along and makes similar "fun" necessary for e.g. ALSA... > because "pine" still doesn't get UTF-8 right, and nobody is apparently > ever going to fix it. Oh, well. But at least I know I'm doing something > _wrong_, which in itself is a good thing.). Heh. Took you long enough - "using pine" should've been a dead giveaway from the very beginning ;-)