From owner-freebsd-arch@FreeBSD.ORG Wed Aug 25 19:09:08 2010 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 26CD91065693 for ; Wed, 25 Aug 2010 19:09:08 +0000 (UTC) (envelope-from xcllnt@mac.com) Received: from asmtpout024.mac.com (asmtpout024.mac.com [17.148.16.99]) by mx1.freebsd.org (Postfix) with ESMTP id 0C3DC8FC0A for ; Wed, 25 Aug 2010 19:09:07 +0000 (UTC) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; charset=us-ascii Received: from macbook-pro.jnpr.net (natint3.juniper.net [66.129.224.36]) by asmtp024.mac.com (Sun Java(tm) System Messaging Server 6.3-8.01 (built Dec 16 2008; 32bit)) with ESMTPSA id <0L7Q00C3U2J4B930@asmtp024.mac.com>; Wed, 25 Aug 2010 12:09:04 -0700 (PDT) X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 ipscore=0 phishscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx engine=6.0.2-1004200000 definitions=main-1008250146 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.0.10011,1.0.148,0.0.0000 definitions=2010-08-25_09:2010-08-25, 2010-08-25, 1970-01-01 signatures=0 From: Marcel Moolenaar In-reply-to: Date: Wed, 25 Aug 2010 12:09:04 -0700 Message-id: <9EA74D18-1CA4-4F3D-9CE5-0BD1B4D6B7BB@mac.com> References: <34EF2360-1B68-4E0C-8CCE-409CE141D0B8@mac.com> To: Garrett Cooper X-Mailer: Apple Mail (2.1081) Cc: "freebsd-arch@FreeBSD.org Arch" Subject: Re: RFC: root mount enhancement (round 2) X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Aug 2010 19:09:08 -0000 On Aug 25, 2010, at 11:18 AM, Garrett Cooper wrote: > On Wed, Aug 25, 2010 at 8:58 AM, Marcel Moolenaar wrote: >> Summary of round 1: > > ... > >> To re-iterate: the logic is recursive. After mounting some file system >> as root, the kernel will follow the directives in /.mount.conf (if the >> file exists) for remounting the root file system. At each iteration the >> kernel will remount devfs under /dev and remount the current root file >> system under /.mount within the new root file system. > > I like the proposal, but like Ed, I do have a concern with > infinite recursion. Should a breadcrumb be added to prevent infinite > recursion with the mounts, or is it game over, egg on your face, if > you create an infinite recursion situation? Since we have a trail of file systems (by virtue of mounting the previous root under the new root at /.mount), we should be able to detect when we're about to mount from a device previously used to mount from. Alternatively or on top of that, we can have a global limit on the recursion depth. Unless this is something we want to control through /.mount.conf, I don't think it's an item that needs to be closed or nailed down before we can move ahead. Put differently: I can implement both to start with... -- Marcel Moolenaar xcllnt@mac.com