Re: [PATCH v2 2/5] tools include: add dis-asm-compat.h to handle version differences

From: Quentin Monnet <quentin@isovalent.com>
To: Andres Freund <andres@anarazel.de>
Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	Alexei Starovoitov <ast@kernel.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Jiri Olsa <jolsa@kernel.org>, Sedat Dilek <sedat.dilek@gmail.com>
Subject: Re: [PATCH v2 2/5] tools include: add dis-asm-compat.h to handle version differences
Date: Mon, 18 Jul 2022 09:58:42 +0100	[thread overview]
Message-ID: <2d2e60d9-f340-4c2d-e123-a858c46fae16@isovalent.com> (raw)
In-Reply-To: <20220715193927.x6xy4h7n5rrh2ndc@awork3.anarazel.de>

On 15/07/2022 20:39, Andres Freund wrote:
> Hi,
> 
> On 2022-07-05 14:44:07 +0100, Quentin Monnet wrote:
>>> diff --git a/tools/include/tools/dis-asm-compat.h b/tools/include/tools/dis-asm-compat.h
>>> new file mode 100644
>>> index 000000000000..d1d003ee3e2f
>>> --- /dev/null
>>> +++ b/tools/include/tools/dis-asm-compat.h
>>> @@ -0,0 +1,53 @@
>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>
>> Any chance you could contribute this wrapper as dual-licenced
>> (GPL-2.0-only OR BSD-2-Clause), for better compatibility with the rest
>> of bpftool's code?
> 
> Happy to do that from my end - however, right now it includes
> linux/compiler.h, which is GPL-2.0. I don't know what the policy around that
> is - is it just a statement about the licence of the header itself, or does it
> effectively include its dependencies?

My understanding is that programs using a GPL header need to be released
as GPL, but I don't believe they have to be only GPL, the dual-license
should cover the requirements. If someone wanted to redistribute the
code from the new header dis-asm-compat.h as BSD only, they would
probably have to get rid of the GPL-only dependencies though. But again,
this is only my understanding, and “I am not a lawyer”.

> 
> FWIW, linux/compiler.h is also included from bpftool.
> 
> If preferrable, I can replace the linux/compiler.h include by just using
> __attribute__((__unused__)) directly or by using a (void) cast to avoid the
> unused-parameter pedantry.

If compiler.h is just needed for the “unused” attribute, I wouldn't mind
doing that.

Thanks,
Quentin