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Date: Wed, 22 Nov 2017 14:23:29 +0100
From: Christoph Hellwig <hch@lst.de>
To: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Christoph Hellwig <hch@lst.de>,
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        Charlemagne Lasse <charlemagnelasse@gmail.com>,
        Carmen Bianca Bakker <carmenbianca@fsfe.org>
Subject: Re: [patch V4 01/11] Documentation: Add license-rules.rst to
        describe how to properly identify file licenses
Message-ID: <20171122132328.GA26023@lst.de>
References: <20171116183306.103584007@linutronix.de> <20171116184358.398030394@linutronix.de> <alpine.DEB.2.20.1711171057240.1709@nanos> <20171117150639.0e706421@vento.lan> <alpine.DEB.2.20.1711171850330.2186@nanos> <20171117183946.GA28533@lst.de> <alpine.DEB.2.20.1711221207460.1751@nanos> <20171122095117.49c558a4@vento.lan>
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On Wed, Nov 22, 2017 at 09:51:17AM -0200, Mauro Carvalho Chehab wrote:
> Also, one may forget that headers use /**/ and end by doing the wrong
> thing, as a common practice is to just cut-and-paste the same copyright
> header on both C and H files at development time.

Yes.

> Make headers_install could replace such macros by SPDX comments when
> installing on userspace.

Agreed.  Or for that matter we could simply stick to the comment version
for UAPI headers only, and have a macro for everything else.

> >    - Breaks in assembly, boot and other special source files. There was no
> >      easy solution to that and the result would have been to have macros in
> >      some files and not in others.
> 
> At the end, we have different markups, depending on the file type.
> I guess the main problem of using a macro is that a module composed
> by multiple C files will end by defining it multiple times. Not sure
> if gcc would do the right thing on grouping everything altogether
> and producing the right equivalent to MODULE_LICENSE().

We'd basically need to add a new entry to a section, similar to how
say __setup works in the core kernel.  But I think the important bit
is to start with a macro now, even if it has zero functionality to
start with - at least that enables us to fill the functionality once
needed.

> Also, at least on media, I found cases where the same module
> has multiple licenses, e. g. some files that are grouped together on
> a module are GPL v2 only, while others are GPL v2+.

A module always has the least permissive license of all files.