From owner-freebsd-current Wed Mar 20 22:09:14 1996 Return-Path: owner-current Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id WAA25899 for current-outgoing; Wed, 20 Mar 1996 22:09:14 -0800 (PST) Received: from VX23.CC.MONASH.EDU.AU (vx23.cc.monash.edu.au [130.194.1.23]) by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id WAA25891 for ; Wed, 20 Mar 1996 22:09:05 -0800 (PST) Received: from moa.cc.monash.edu.au (george@moa.cc.monash.edu.au) by vaxc.cc.monash.edu.au (PMDF V5.0-6 #16291) id <01I2LWBN5CZE9I5ANJ@vaxc.cc.monash.edu.au> for current@freebsd.org; Thu, 21 Mar 1996 17:07:13 +1100 Received: (george@localhost) by moa.cc.monash.edu.au (8.6.10/8.6.4) id QAA12180 for current@freebsd.org; Thu, 21 Mar 1996 16:07:07 +1000 Date: Thu, 21 Mar 1996 16:07:07 +1000 From: George Scott Subject: Re: DEVFS vs "regular /dev" To: current@freebsd.org Message-id: <199603210607.QAA12180@moa.cc.monash.edu.au> MIME-version: 1.0 Content-type: TEXT/PLAIN Content-transfer-encoding: 7BIT Sender: owner-current@freebsd.org X-Loop: FreeBSD.org Precedence: bulk >>> This assumes that the file system abstractions currently in place >>> change as well, since the /dev FS can't be mounted *after* the / FS >>> has been mounted as an inferior FS -- >> why not? >> you don't need a mounted /dev to mount root. >> that's done specially. > > So you don't need a mounted root to have a mounted /dev, of course! > > This makes it possible to remount root r/w without unmounting the > devfs (and so still needing /dev). > >>> the /dev has to be there as >>> an overlay mount (translucent FS), and that means FS changes to allow >>> translucence and to divorce volume mappings from the need for a mount >>> point (basically, a shadow / and /dev on which the devfs /dev is mounted >>> and the real / is mounted over top of the shadow /). >> >> I think that's not needed > > Root remount, again. If you divorce the mappings, you can mount root > over and over despite devfs being mounted by default. I'm not sure I understand all this, but never mind. What would be wrong with doing something like this.. At boot time the kernel creates a memory-filesystem (mfs or other) with a /dev directory. During the device probes this /dev gets populated with appropriate device entries. At the end of the kernel initialisations the kernel union mounts the root disk over the memory /. For those detractors in a previous thread this would also allow those who are so inclined to have their own custom modifications to /dev or even to remount their root without the union to keep using the old method. George.