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Message-ID: <073cf884-e191-e323-1445-b79c86759557@linux.dev>
Date:   Fri, 19 May 2023 12:01:09 -0700
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Subject: Re: a small question about bpftool struct_ops
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To:     Zhouyi Zhou <zhouzhouyi@gmail.com>, bpf@vger.kernel.org,
        linux-kernel <linux-kernel@vger.kernel.org>
References: <CAABZP2wiPdij+q_Nms08e8KbT9+CgXuoU+MO3dyoujG_1PPHAQ@mail.gmail.com>
From:   Martin KaFai Lau <martin.lau@linux.dev>
In-Reply-To: <CAABZP2wiPdij+q_Nms08e8KbT9+CgXuoU+MO3dyoujG_1PPHAQ@mail.gmail.com>
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On 5/19/23 5:07 AM, Zhouyi Zhou wrote:
> Dear developers:
> I compiled bpftool and bpf tests in mainline (2d1bcbc6cd70),
> but when I invoke:
> bpftool struct_ops register bpf_cubic.bpf.o
> 
> the command line fail with:
> libbpf: struct_ops init_kern: struct tcp_congestion_ops data is not
> found in struct bpf_struct_ops_tcp_congestion_ops

At the machine trying to register the bpf_cubic, please dump the vmlinux btf and 
search for bpf_struct_ops_tcp_congestion_ops and paste it here:

For example:
#> bpftool btf dump file /sys/kernel/btf/vmlinux

...

[74578] STRUCT 'bpf_struct_ops_tcp_congestion_ops' size=256 vlen=3
         'refcnt' type_id=145 bits_offset=0
         'state' type_id=74569 bits_offset=32
         'data' type_id=6241 bits_offset=512