linux-kernel - Re: Linux & FAT32 label

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Message-ID: <CAHp75VfwLh9eH992nB1TiOVYOpEV6OSTGkbLau=eQRPeczeFyA@mail.gmail.com>
Date:   Sun, 5 Nov 2017 15:56:53 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Pali Rohár <pali.rohar@...il.com>
Cc:     Andreas Bombe <aeb@...ian.org>, Karel Zak <kzak@...hat.com>,
        util-linux@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrius Štikonas <andrius@...konas.eu>,
        Curtis Gedak <gedakc@...il.com>
Subject: Re: Linux & FAT32 label

On Sun, Nov 5, 2017 at 3:39 PM, Pali Rohár <pali.rohar@...il.com> wrote:
> On Tuesday 31 October 2017 10:35:48 Andy Shevchenko wrote:
>> On Mon, Oct 16, 2017 at 4:12 AM, Andreas Bombe <aeb@...ian.org> 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

> 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).

-- 
With Best Regards,
Andy Shevchenko