Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755661Ab2BGHwo (ORCPT ); Tue, 7 Feb 2012 02:52:44 -0500 Received: from mail.mnsspb.ru ([84.204.75.2]:50960 "EHLO mail.mnsspb.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751349Ab2BGHwn (ORCPT ); Tue, 7 Feb 2012 02:52:43 -0500 Date: Tue, 7 Feb 2012 11:55:53 +0400 From: Kirill Smelkov To: Kay Sievers Cc: linux-kernel@vger.kernel.org Subject: Re: No /dev/root with devtmpfs? Message-ID: <20120207075553.GB8632@tugrik.mns.mnsspb.ru> References: <20120206111853.GA11506@tugrik.mns.mnsspb.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Organization: Marine Bridge & Navigation Systems User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1686 Lines: 36 On Mon, Feb 06, 2012 at 08:45:24PM +0100, Kay Sievers wrote: > On Mon, Feb 6, 2012 at 12:18, Kirill Smelkov wrote: > > Recently I've reworked my system not to use udev, but use devtmpfs > > instead and discovered there is no /dev/root symlink in devtmpfs case. > > > > My setup uses /dev/root early to know what is the boot device and then > > do some operations on it like checksumming, etc... > > > > Now when /dev/root is gone the best workaround I could come up with is > > to ? grep /proc/partitions for '[hs]d[a-z]1' ?but it's ugly and will > > break when there are several block devices attached. > > > > Is it somehow possible to add /dev/root to devtmpfs? > > No, devtmpfs has no business in knowing anything about the rootfs or > who mounted what ans where. I can not create such links. > > The entire concept of /dev/root is flawed anyway, and nothing should > really depend on that. > > Modern filesystems will not offer a direct relation to a single block > device, they allocate an superblock which has a major == 0, so there > can be by definition never such a link. Better get rid of all uses of > /dev/root, it will just fail in the future. Kay, thanks for explanation. Though now I'm confused about how to know on what "place" root filesystem was mounted... To me the question makes sense, but you say with modern filesystems there by definition is no answer (or did I misunderstood you?) Strange... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/