Subject: RE: Re: Re: Clarification on bpftool dual licensing

From: Toke Høiland-Jørgensen <[email-masked]>
Date: Fri, 19 Nov 2021 13:54:19 +0100

Martin Kelly <[email-masked]> writes:

>> > One other, related question: vmlinux.h (generated by "bpftool btf dump file
>> /sys/kernel/btf/vmlinux format c"), does not currently contain a license
>> declaration. I assume this would have to be a GPL header, since vmlinux.h
>> references many GPL'd Linux kernel structs and similar, though again I'm not a
>> lawyer and therefore am not certain. Would you all agree with this? If so, any
>> objection to a patch adding an SPDX line to the generated vmlinux.h?
>>
>> Is vmlinux DWARF data GPL'ed? I certainly hope not. So vmlinux.h
>> shouldn't be licensed under GPL.
>
> I have no idea; I had assumed that a struct definition coming from a
> GPL-licensed header would have to be GPL, but again, not a lawyer, and
> I could totally be wrong. If not GPL though, what would the license
> be? Is it just "output of a program" and therefore license-less, even
> though the output happens to be code?

Totally not a lawyer either, but:

There's (generally, in many jurisdictions, etc), a minimum bar for when
something is considered a "creative work" and thus copyrightable. Debug
output *could* fall short of this (and thus not be copyrightable at
all). It could also fall under the same "API" umbrella as that famous
Google v Oracle case. Or it could fall under the "syscall exception" of
the kernel source.

I guess it would take a court decision to know either way. IMO it would
make sense if vmlinux.h is not copyrightable for whatever reason, but,
again, IANAL :)

Anyway, while we obviously can't resolve legal matters on the mailing,
we can express the *intention* of the community, which is what the
licensing document is trying to do. So it totally makes sense to mention
vmlinux.h here; the question is what should such a text say?

-Toke