From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1WgENO-0000jn-LE for mharc-grub-devel@gnu.org; Fri, 02 May 2014 10:23:46 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59519) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WgENL-0000gM-KQ for grub-devel@gnu.org; Fri, 02 May 2014 10:23:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WgENK-0003Zb-JH for grub-devel@gnu.org; Fri, 02 May 2014 10:23:43 -0400 Received: from v6.chiark.greenend.org.uk ([2001:ba8:1e3::]:40639 helo=chiark.greenend.org.uk) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WgENK-0003ZP-Dw for grub-devel@gnu.org; Fri, 02 May 2014 10:23:42 -0400 Received: from [172.20.153.9] (helo=riva.pelham.vpn.ucam.org) by chiark.greenend.org.uk (Debian Exim 4.72 #1) with esmtps (return-path cjwatson@ubuntu.com) id 1WgENI-0008MU-1c; Fri, 02 May 2014 15:23:40 +0100 Received: from ns1.pelham.vpn.ucam.org ([172.20.153.2] helo=riva.ucam.org) by riva.pelham.vpn.ucam.org with esmtps (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from ) id 1WgEN9-0003ZF-Ch; Fri, 02 May 2014 15:23:31 +0100 Date: Fri, 2 May 2014 15:23:30 +0100 From: Colin Watson To: Sree Harsha Totakura Subject: Re: Why ignore UUID when linux root device is an LV? Message-ID: <20140502142330.GC7028@riva.ucam.org> References: <53639575.6020109@totakura.in> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53639575.6020109@totakura.in> User-Agent: Mutt/1.5.21 (2010-09-15) X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2001:ba8:1e3:: Cc: grub-devel@gnu.org X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 02 May 2014 14:23:44 -0000 On Fri, May 02, 2014 at 02:54:13PM +0200, Sree Harsha Totakura wrote: > I would like to know why UUID is not used for root device in Linux > kernel's `root=' parameter when the root device uses LVM. Filesystem UUIDs on LVM aren't necessarily unique in the presence of snapshots; and not all initramfses cope with root=UUID=* in any event, for instance: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=612402 Every time this breaks in GRUB and we end up using UUIDs on LVM again, I get a slew of Debian bug reports until I figure it out and fix it. The LVM device names themselves are sufficiently stable that there should be no need to introduce additional layers of complexity by using filesystem UUIDs. In general we only need them in cases where the device names are not stable. > >From the commit log: > > commit 507736c87c49712ac618169d17a659bd6c25eecc > > Author: Colin Watson > > Date: Fri Jul 2 12:32:05 2010 +0100 > > > > * util/grub-mkconfig_lib.in (uses_abstraction): New function. > > * util/grub.d/10_linux.in: Use it to check for LVM, so that > > LVM-on-RAID is handled correctly. > > I see that this condition is added to address LVM/RAID configurations. > But, I guess it is similar to LVM/LUKS; is it not? I'm not sure, but perhaps GRUB_ENABLE_CRYPTODISK=y would help grub-mkconfig notice this? Regards, -- Colin Watson [cjwatson@ubuntu.com]