Re: [PATCH bpf-next] bpftool: Add SPDX identifier to btf-dump-file output

[Daniel Xu]

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@xxxxxxxxx> 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@xxxxxxxxx>
>> ---
>>  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?

Thanks,
Daniel