Dual-license XML files BSD-2-Clause and CC-BY-4.0

[rtwfroody]

BSD-2-Clause is used so the C code generated from those files can be used in GPLv2 open source projects (specifically, OpenOCD) and the CC-BY-4.0 clause is the standard license for work produced by the RISC-V Foundation.

[rpsene]

@rtwfroody LGTM.

[rtwfroody]

@borneoa does this work for you?

[borneoa]

Few issues in the generated header for the C files:

• the correct SPDX tag should be SPDX-License-Identifier: CC-BY-4.0 OR BSD-2-Clause in a single line, or accordingly to https://wiki.spdx.org/view/SPDX_FAQ it should be SPDX-License-Identifier: (CC-BY-4.0 or BSD-2-Clause)
• the SPDX tag should be in the very first line of the file, to help automatic tools to build the SW BOM
• the preferred comment style for the SPDX is /* comment */ for files.h, while is // comment for files.c. See https://www.kernel.org/doc/html/v4.18/process/license-rules.html#license-identifier-syntax

The first point should be a legal requirement, while the other two are highly welcome but can still be managed through a manual editing of the files before integration in another project like OpenOCD

[rtwfroody]

• the correct SPDX tag should be SPDX-License-Identifier: CC-BY-4.0 OR BSD-2-Clause in a single line, or accordingly to https://wiki.spdx.org/view/SPDX_FAQ it should be SPDX-License-Identifier: (CC-BY-4.0 or BSD-2-Clause)

Fixed.

• the SPDX tag should be in the very first line of the file, to help automatic tools to build the SW BOM

Fixed.

• the preferred comment style for the SPDX is /* comment */ for files.h, while is // comment for files.c. See https://www.kernel.org/doc/html/v4.18/process/license-rules.html#license-identifier-syntax

I've left this as-is. /* */ works in every C compiler. // does not (although you might have to go back a way to find a compiler that doesn't accept //).

[pdonahue-ventana]

// comments were standardized in regular C in 1999, but using old-school comments is fine and will make C89 people happy.

I was going to advise against using Python f-strings for a similar reason since that requires Python 3.6. However, I see that registers.py already uses f-strings extensively (which nobody seems to be complaining about) and 3.6 is now seven years old. So that's fine. And f-strings are so much nicer than the old clunky ways.

[borneoa]

If I remember correctly, the SPDX spec was requiring to use a "single line comment" so the decision was to use // comment style. But this was not compatible with files.h included by assembly files.
At the end, // comment was kept for files.c only, while the backward compatible /* comment */ was used in files.h.
Anyway, not a big issue; let's keep this simple.

The result is now good for me.

There is one new issue with build/Makefile, commented in the patch review

[borneoa]

build issue in this commit

[borneoa]

By removing this make's target debug_defines.% the build make debug_defines fails on clean build, e.g. after a clean git clone
You need to drop debug_defines.h and debug_defines.c at line 74

[rtwfroody]

Good point. Fixed.

[borneoa]

Need to remove the dependencies debug_defines.h and debug_defines.c because the files are not added anymore after line 75 has been removed

[borneoa]

I'm fine with it. Thanks