From owner-svn-src-all@FreeBSD.ORG Sun Apr 24 14:14:07 2011 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 72F21106566C; Sun, 24 Apr 2011 14:14:07 +0000 (UTC) (envelope-from nwhitehorn@freebsd.org) Received: from mail.icecube.wisc.edu (trout.icecube.wisc.edu [128.104.255.119]) by mx1.freebsd.org (Postfix) with ESMTP id 172A58FC08; Sun, 24 Apr 2011 14:14:06 +0000 (UTC) Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.icecube.wisc.edu (Postfix) with ESMTP id 329B75811B; Sun, 24 Apr 2011 09:14:06 -0500 (CDT) X-Virus-Scanned: amavisd-new at icecube.wisc.edu Received: from mail.icecube.wisc.edu ([127.0.0.1]) by localhost (trout.icecube.wisc.edu [127.0.0.1]) (amavisd-new, port 10030) with ESMTP id kReVdMAqmRLn; Sun, 24 Apr 2011 09:14:06 -0500 (CDT) Received: from wanderer.tachypleus.net (unknown [76.210.65.155]) by mail.icecube.wisc.edu (Postfix) with ESMTP id 4C21D5811A; Sun, 24 Apr 2011 09:14:05 -0500 (CDT) Message-ID: <4DB4302B.5050501@freebsd.org> Date: Sun, 24 Apr 2011 09:14:03 -0500 From: Nathan Whitehorn User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.2.15) Gecko/20110317 Thunderbird/3.1.9 MIME-Version: 1.0 To: Robert Watson References: <201104240923.p3O9N8QG025386@svn.freebsd.org> <20110424095736.GA92492@freebsd.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: svn-src-head@freebsd.org, Alexander Best , Alexander Motin , src-committers@freebsd.org, svn-src-all@freebsd.org Subject: Re: svn commit: r220983 - head X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 24 Apr 2011 14:14:07 -0000 On 04/24/11 05:49, Robert Watson wrote: > > On Sun, 24 Apr 2011, Alexander Best wrote: > >>> ============================================================================== >>> >>> --- head/UPDATING Sun Apr 24 08:58:58 2011 (r220982) >>> +++ head/UPDATING Sun Apr 24 09:23:08 2011 (r220983) >>> @@ -28,8 +28,9 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 9. >>> removed and replaced by respective CAM drivers. If you are using >>> ATA device names in /etc/fstab or other places, make sure to update >>> them respectively (adX -> adaY, acdX -> cdY, afdX -> daY, astX -> saY, >>> - where 'Y's are the sequential numbers for each type in order of >>> - detection, unless configured otherwise with tunables, see cam(4)). >>> + where 'Y's are the sequential numbers starting from zero for each type >>> + in order of detection, unless configured otherwise with tunables, >>> + see cam(4)). >> >> maybe an extra sentence mentioning the fact that {geom,ufs}-labels and >> ufsids are preferred over device nodes nowadays would be a good idea? > > If this is true, that's what our installer needs to do. Does our > installer do that? > > (In general, a reasonable definition of "preferred" is "what the > installer does" -- if that's not the case, it's a serious bug.) Our installer does not do that. I outlined the reasons in another earlier email, but the summary is that labels seem to be somewhat fragile. Gpart supports a partition-generic labeling interface for three schemes: PC98, GPT, and APM. The installer now supports setting labels on all of these. The appearance of labeled geom providers happens in a different module, glabel, which relies on a totally parallel parse of the partition map. As a result, labeled partitions appearing in /dev works only on GPT volumes, and even then, due to endianness bugs, only on little-endian platforms. Glabel is also not guaranteed available by gpart, and I'm a little dubious that reparses happen at the correct time with 100% reliability. The other, more minor, difficulty, is that it is somewhat difficult to get the labeled provider name from the gpart provider (you have to try to cross-correlate names, and there may be many label providers to choose from for the same partition). If gpart were modified to provide label providers itself based on its generic labeling mechanism, and to provide the name of those providers in its config XML, using labels by default in the installer would be trivial and I would have it in the tree within 5 minutes of getting that commit mail. Unfortunately, I don't have time to do the requisite gpart modifications (which probably aren't that hard) at this time. -Nathan