On Fri, Oct 20, 2017 at 9:20 AM, Fendt, Oliver <oliver.fendt@...> wrote:

great to see this direction of development.
This will are least clarify all the files which carry nothing expect the Marko
MODUL_LICENSE("GPL");
Because one of the interesting questions is "is this a legally binding expression
of licensing?"

The MODULE_LICENSE macro used in the kernel is a clear license statement.
And better than a terse "Copyright (c) John Doe, GPL" that is seen in
the kernel
since there is a clear documentation of its meaning in the kernel's
module.h [0] :

* The following license idents are currently accepted as indicating free
* software modules
*
* "GPL" [GNU Public License v2 or later]
* "GPL v2" [GNU Public License v2]
* "GPL and additional rights" [GNU Public License v2 rights and more]
* "Dual BSD/GPL" [GNU Public License v2
* or BSD license choice]
* "Dual MIT/GPL" [GNU Public License v2
* or MIT license choice]
* "Dual MPL/GPL" [GNU Public License v2
* or Mozilla license choice]
*
* The following other idents are available
*
* "Proprietary" [Non free products]
[...]

So MODULE_LICENSE("GPL") means clearly "GNU Public License v2 or later"
and nothing else. I cannot comment on whether such a license statement would
be legally binding or not, but at least there is no ambiguity about
what this means.
And IMHO this is as good as an SPDX license identifier and as good as it gets
short of any other licensing indications.

Since the MODULE_LICENSE is only for kernel modules, there was a need
for something that could be applied elsewhere, hence the use of SPDX
identifiers. Note that there were talks to use a macro instead of a comment.
It may come back in the future as it would have the added benefit to inject
license ids in the built binaries (the same way a MODULE_LICENSE ends
up in a built LKM)

[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/module.h?id=refs/tags/v4.10#n172

--
Cordially
Philippe Ombredanne