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Date:   Tue, 15 Mar 2022 21:57:56 -0700
From:   "Daniel Xu" <dxu@dxuuu.xyz>
To:     "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
Cc:     "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
        "Alexei Starovoitov" <ast@kernel.org>,
        "Daniel Borkmann" <daniel@iogearbox.net>,
        "Andrii Nakryiko" <andrii@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next] bpftool: Add SPDX identifier to btf-dump-file output
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On Tue, Mar 15, 2022, at 4:39 PM, Alexei Starovoitov wrote:
> On Tue, Mar 15, 2022 at 4:10 PM Daniel Xu <dxu@dxuuu.xyz> wrote:
>>
>> Hi Alexei,
>>
>> On Tue, Mar 15, 2022, at 2:38 PM, Alexei Starovoitov wrote:
>> > On Sun, Mar 13, 2022 at 4:01 PM Daniel Xu <dxu@dxuuu.xyz> wrote:
>> >>
>> >> A concern about potential GPL violations came up at the new $DAYJOB when
>> >> I tried to vendor the vmlinux.h output. The central point was that the
>> >> generated vmlinux.h does not embed a license string -- making the
>> >> licensing of the file non-obvious.
>> >>
>> >> This commit adds a LGPL-2.1 OR BSD-2-Clause SPDX license identifier to
>> >> the generated vmlinux.h output. This is line with what bpftool generates
>> >> in object file skeletons.
>> >>
>> >> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
>> >> ---
>> >>  tools/bpf/bpftool/btf.c | 1 +
>> >>  1 file changed, 1 insertion(+)
>> >>
>> >> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
>> >> index a2c665beda87..fca810a27768 100644
>> >> --- a/tools/bpf/bpftool/btf.c
>> >> +++ b/tools/bpf/bpftool/btf.c
>> >> @@ -425,6 +425,7 @@ static int dump_btf_c(const struct btf *btf,
>> >>         if (err)
>> >>                 return err;
>> >>
>> >> +       printf("/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */\n\n");
>> >
>> > I don't think we can add any kind of license identifier
>> > to the auto generated output.
>> > vmlinux.h is a pretty printed dwarfdump.
>>
>> Just so I understand better, when you say "I don't think we can",
>> do you mean:
>>
>> 1) There may be legal issues w/ adding the license identifier
>> 2) It doesn't make sense to add the license header
>> 3) Something else?
>
> 2

Got it, thanks.