From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: Re: [PATCH bpf-next v5 00/10] BTF: BPF Type Format
Date: Thu, 7 Jun 2018 17:25:24 -0300
Message-ID: <20180607202524.GH17292@kernel.org>
References: <20180607190510.qtj7gq4wbfewcn4g@kafai-mbp>
 <20180607193029.GG17292@kernel.org>
 <20180607200701.bvsjzoq56rnggwfd@kafai-mbp>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: netdev@vger.kernel.org, Alexei Starovoitov <ast@fb.com>,
        Daniel Borkmann <daniel@iogearbox.net>, kernel-team@fb.com,
        Wang Nan <wangnan0@huawei.com>, Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ingo Molnar <mingo@kernel.org>
To: Martin KaFai Lau <kafai@fb.com>
Return-path: <netdev-owner@vger.kernel.org>
Received: from mail.kernel.org ([198.145.29.99]:56168 "EHLO mail.kernel.org"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S932491AbeFGUZ2 (ORCPT <rfc822;netdev@vger.kernel.org>);
        Thu, 7 Jun 2018 16:25:28 -0400
Content-Disposition: inline
In-Reply-To: <20180607200701.bvsjzoq56rnggwfd@kafai-mbp>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

Em Thu, Jun 07, 2018 at 01:07:01PM -0700, Martin KaFai Lau escreveu:
> On Thu, Jun 07, 2018 at 04:30:29PM -0300, Arnaldo Carvalho de Melo wrote:
> > So this must be available in a newer llvm version? Which one?

> I should have put in the details in my last email or
> in the commit message, my bad.
 
> 1. The tools/testing/selftests/bpf/Makefile has the CLANG_FLAGS and
>    LLC_FLAGS needed to compile the bpf prog.  It requires a new
>    "-mattr=dwarf" llc option which was added to the future
>    llvm 7.0.
 
>    Hence, I have been using the llvm's master in github which
>    also has the llvm-objcopy.
 
> 2. The kernel's btf part only focus on the BPF map.
>    Hence, the testing bpf program should have the map's key
>    and map's value.  e.g. tools/testing/selftests/bpf/test_btf_haskv.c

Thanks for the version required to test this, but where is this
test_btf_haskv.c file? Which tree? net-next?

Ok, just pulled torvalds/master and there it is. Gotcha.

struct bpf_map_def SEC("maps") __bpf_stdout__ = {
       .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
       .key_size = sizeof(int),
       .value_size = sizeof(u32),
       .max_entries = __NR_CPUS__,
};

This map is in the above hello.c example, but I guess its way too simple
:-)

Ok, I'll test this at home in another machine where I have the llvm's
git repo.

- Arnaldo