netdev - Re: BPF logging infrastructure. Was: [PATCH bpf-next 4/6] tools: add new members to bpf_attr.raw

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Date:   Thu, 16 Jul 2020 22:19:03 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     bpf <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Networking <netdev@...r.kernel.org>,
        Kernel Team <kernel-team@...com>,
        Blake Matheny <bmatheny@...com>
Subject: Re: BPF logging infrastructure. Was: [PATCH bpf-next 4/6] tools: add new members to bpf_attr.raw_tracepoint in bpf.h

Andrii Nakryiko <andrii.nakryiko@...il.com> writes:

>> So myself and Toke are wearing 'bpf user' hat in that context.
>> Both of us indicated that libbpf output is too verbose.
>> Your response "just send a patch" is a sure way to turn away more users.
>>
>
> I can't find any such complaint from Toke in this thread, and can't
> really recall something like that from recent discussions. I'd rather
> have him speak for himself.

I think what I said (not in this thread, way back during some other
discussion) was that I agreed that libbpf was being too verbose by
dumping all the sections and relocations it finds when reading an ELF
file, which causes the useful error messages to get lost. I would like
to see those messages demoted to another log level, or removed
altogether.

I won't have time to look more at this right now, but I do plan to
circle back to it: I agree with you that we need to make this more
friendly. And yes, I also think this should include finding a way to
disambiguate between different conditions leading to the same error from
the kernel. I've run into a lot of the same issues as you when
supporting people who are new to BPF - thank you for the extensive list!

-Toke