[M] Change in coreboot[master]: mainboard: Add SPDX license headers to Makefiles

[Martin L Roth (Code Review)]

Attention is currently required from: Felix Singer, Jason Nien, Jeremy Soller, Michael Niewöhner, Martin Roth, Tim Crawford, Nico Huber, Tarun Tuli, Damien Zammit, Subrata Banik, Maxim Polyakov, Kapil Porwal, Alexander Couzens, Werner Zeh, Evgeny Zinoviev.

Martin L Roth has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/68982 )

Change subject: mainboard: Add SPDX license headers to Makefiles
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Patch Set 2:

(2 comments)

Patchset:

PS2:
> see util/lint/lint-000-license-headers; currently Makefile. […]

We have a linter for the SPDX headers, but because it kills the build it really only works if all of the files in a class already have the header.  The process is usually that we need to fix all of the issues, then we can enable the linter.

PS2:
> > I don't understand these questions. […]

It's not that AMD is actually demanding this, but the tool that they're using (palamida scan) is, in my opinion, not very good.  License resolution is a very manual process unless each file has an embedded header.

Basically, to make things easier for the AMD team and because I expect that other teams will be using similar tools in the future, I'm trying to make sure that all of the files in the coreboot tree have a license embedded, if possible.  I believe that we've now got licenses in all of the source code, so I'm moving on to things like Makefiles and Kconfig where it's very spotty.

As far as the license, I don't know that it's spelled out anywhere, but the top level license of coreboot has always been specified to be GPL V2.  That's the license contained in the top level "COPYING" file. The best description I've found of this is here:
https://stackoverflow.com/questions/11670368/gpl-copyright-notice-when-contr...

You're absolutely right that we should spell this out better in the contributing section of the docs.  As always, our documentation is way behind.

I'll add the reason for the change in future patches - I honestly didn't think about it, or even that it was a question.