linux-kernel - Re: [PATCH net-next v1] samples/bpf: Partially fixes the bpf.o build

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Date:   Sat, 27 Jan 2018 00:10:25 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Mickaël Salaün <mic@...ikod.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     linux-kernel@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v1] samples/bpf: Partially fixes the bpf.o build

On 01/26/2018 09:30 AM, Mickaël Salaün wrote:
> On 26/01/2018 03:16, Alexei Starovoitov wrote:
>> On Fri, Jan 26, 2018 at 01:39:30AM +0100, Mickaël Salaün wrote:
>>> Do not build lib/bpf/bpf.o with this Makefile but use the one from the
>>> library directory.  This avoid making a buggy bpf.o file (e.g. missing
>>> symbols).
>>
>> could you provide an example?
>> What symbols will be missing?
>> I don't think there is an issue with existing Makefile.
> 
> You can run this commands:
> make -C samples/bpf; nm tools/lib/bpf/bpf.o > a; make -C tools/lib/bpf;
> nm tools/lib/bpf/bpf.o > b; diff -u a b
> 
> Symbols like bzero and sys_bpf are missing with the samples/bpf
> Makefile, which makes the bpf.o shrink from 25K to 7K.

I've applied it to bpf-next, thanks Mickaël!