From owner-freebsd-stable@FreeBSD.ORG Wed Jun 1 07:39:52 2011 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9D7F5106566B for ; Wed, 1 Jun 2011 07:39:52 +0000 (UTC) (envelope-from tzim@tzim.net) Received: from orlith.tzim.net (unknown [IPv6:2001:41d0:2:1d32:21c:c0ff:fe82:92c6]) by mx1.freebsd.org (Postfix) with ESMTP id 39D578FC12 for ; Wed, 1 Jun 2011 07:39:52 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=secure.tzim.net) by orlith.tzim.net with esmtp (Exim 4.76 (FreeBSD)) (envelope-from ) id 1QRg1v-0008X6-1x for freebsd-stable@freebsd.org; Wed, 01 Jun 2011 09:39:51 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 01 Jun 2011 09:39:50 +0200 From: Arnaud Houdelette To: In-Reply-To: <4DE4D2A8.7050006@FreeBSD.org> References: <63454684d7d46c2ef76cfcc979500612@tzim.net> <4DDF8E02.4060108@FreeBSD.org> <4DE4D2A8.7050006@FreeBSD.org> Message-ID: <04039d080a0dfa9f679644e6aae42b55@tzim.net> X-Sender: tzim@tzim.net User-Agent: RoundCube Webmail/0.5.2 Subject: Re: zfs-root and "safe" atomic updates X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 01 Jun 2011 07:39:52 -0000 On Tue, 31 May 2011 14:36:08 +0300, Andriy Gapon wrote: > First, strictly speaking, the loader is an executable on a > filesystem, there is no > "loader sector". If we consider the earlier boot stages, various > incarnations of > boot2 like gptzfsboot or non-MBR part of zfsboot, then it gets > interesting for > multi-disk configurations. FreeBSD has its view of disks, but BIOS > (which is used > for disk access during boot) has its own different view of disks. So > it's hard > (or impossible) to do an auto-magic thing here. One option could be > to force a > user to use its superior knowledge of a system to explicitly specify > which disk > and which boot block should be used for nextboot-ish purposes. > That, of course, would be prone to footshooting because of the human > nature. For > example, one could specify a wrong disk, boot, see that nothing > changed, realize > the mistake, specify correct disk, never clean out nextboot-ish data > on the wrong > disk, change boot order months later and get badly hurt. But it > could also be > argued that that approach would be better than nothing, which is the > case for ZFS > at the moment. > I didn't though of those footshooting scenarios, but it makes sense. I hope we'll somehow end with a proper solution. (...) > I've rebased the patch to the latest head: > http://people.freebsd.org/~avg/zfsboot.diff > >> And do you still have to change vfs.root.mountfrom once currdev set >> ? > > That should already be included into the patch. Ok. It seems the patch won't apply to 8-stable. How should I proceed to adapt it to 8-stable (if this is possible ?). Or maybe I should juste use HEAD loader ? Thanks again. Arnaud Houdelette