From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751401AbdKEOHx (ORCPT ); Sun, 5 Nov 2017 09:07:53 -0500 Received: from mail-wr0-f172.google.com ([209.85.128.172]:45661 "EHLO mail-wr0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750888AbdKEOHt (ORCPT ); Sun, 5 Nov 2017 09:07:49 -0500 X-Google-Smtp-Source: ABhQp+Smt3BEuyNRcypI6qQRVnuN9Gsjt0sjq1Sna8i0nGfcl4O2wKcKK/lBjSvDIzAioe34bdSUhQ== Date: Sun, 5 Nov 2017 15:07:45 +0100 From: Pali =?utf-8?B?Um9ow6Fy?= To: Andy Shevchenko Cc: Andreas Bombe , Karel Zak , util-linux@vger.kernel.org, "linux-kernel@vger.kernel.org" , Andrius =?utf-8?B?xaB0aWtvbmFz?= , Curtis Gedak , pavel@ucw.cz Subject: Re: Linux & FAT32 label Message-ID: <20171105140745.ze4ttkazeczrqsy7@pali> References: <20171011212435.znmtdnsxcd5ectub@pali> <20171011214426.wa5endlb3kb4yhbv@pali> <20171012085658.iwrusvy4ay4s7hbb@ws.net.home> <20171012092113.2bsb3pzv6un4xahr@pali> <20171012101311.zfvg6edfvszlujom@ws.net.home> <20171012204931.tfd2bhmwu5b6rbpz@pali> <20171016011243.zurh5jhb2y6mczx7@amos.fritz.box> <20171105133929.7cscboxymmpkw634@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sunday 05 November 2017 15:56:53 Andy Shevchenko wrote: > On Sun, Nov 5, 2017 at 3:39 PM, Pali Rohár wrote: > > On Tuesday 31 October 2017 10:35:48 Andy Shevchenko wrote: > >> On Mon, Oct 16, 2017 at 4:12 AM, Andreas Bombe wrote: > >> > On Thu, Oct 12, 2017 at 10:49:31PM +0200, Pali Rohár wrote: > >> >> On Thursday 12 October 2017 12:13:11 Karel Zak wrote: > > >> > I was worried that there might be some scripts or programs that expect > >> > >> If we really care about such scripts another approach might be to > >> introduce a CLI switch to "spec compatible mode" to each tool and > >> suggest in documentation to use it. > >> > >> There are also variants: > >> - spec compatible > >> - WinXX compatible > >> - DOS compatible > >> - etc > > > > I did tests with MS-DOS and Windows versions (results in previous > > email), and they seems to be compatible how they read label. > > > > Based on results I would suggest to ignore label from the boot sector > > when reading label. > > So, for tools which are not doing that to add > > --ignore-boot-sector-label (or alike) [recommended] > > right? > > We don't actually know how many users (scripts) are relying on current > behaviour. > If there are only few, we may introduce backward compatibility switch > > --read-boot-sector-label Current behavior of the last blkid and fatlabel tools is: Try to read label from the root directory. If it does not exist, then fallback to label stored in boot sector. And when fatlabel is changing label it updates both locations. So tools which already uses fatlabel for get & set operations should not be affected as setting new label makes boot and root in sync. New proposed behavior is: Try to read label from the root directory. If not exist, then treat disk as without label. As in current behavior there is no way via fatlabel to read "just only label from boot sector", I think that problems for current scripts is minimal. What about making this new behavior in fatlabel as default with new switch --fallback-to-boot-sector (switch to current behavior) or --read-only-boot-sector (ignores label in root directory) for people who are interested in label stored in boot sector? And what to do with blkid? That cannot have any switch :-( and can have only one behavior. > > This makes behavior consistent with older MS-DOS > > systems and also all Windows systems. This change would be a problem > > only for users who have label stored only in boot sector. After change > > they would not see label anymore -- exactly same what MS-DOS or Windows > > show them. Seems that mkdosfs stores label to both location, since > > support for label was introduced. So different label would be visible > > only for users who used dosfslabel prior to version 3.0.16. > > > > What do you think? > > So, in summary it looks like a documentation needs update (to mark > your research). Which documentation do you mean? -- Pali Rohár pali.rohar@gmail.com