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From:   Zhouyi Zhou <zhouzhouyi@gmail.com>
Date:   Sat, 27 May 2023 07:10:42 +0800
Message-ID: <CAABZP2wBSjevevALA_VF-fTirp-bB42XouKRTuq=RR=60xL=EQ@mail.gmail.com>
Subject: Re: a small question about bpftool struct_ops
To:     Martin KaFai Lau <martin.lau@linux.dev>
Cc:     bpf@vger.kernel.org, linux-kernel <linux-kernel@vger.kernel.org>
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Hi

On Sun, May 21, 2023 at 4:27=E2=80=AFPM Zhouyi Zhou <zhouzhouyi@gmail.com> =
wrote:
>
> Hi
>
> On Sat, May 20, 2023 at 7:37=E2=80=AFAM Zhouyi Zhou <zhouzhouyi@gmail.com=
> wrote:
> >
> > Thank you for responding so quickly ;-)
> >
> > On Sat, May 20, 2023 at 3:01=E2=80=AFAM Martin KaFai Lau <martin.lau@li=
nux.dev> wrote:
> > >
> > > 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 vmli=
nux 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=3D256 vlen=3D=
3
> > >          'refcnt' type_id=3D145 bits_offset=3D0
> > >          'state' type_id=3D74569 bits_offset=3D32
> > >          'data' type_id=3D6241 bits_offset=3D512
> > OK
> > [214398] STRUCT 'bpf_struct_ops_tcp_congestion_ops' size=3D256 vlen=3D3
> >         'refcnt' type_id=3D298 bits_offset=3D0
> >         'state' type_id=3D214224 bits_offset=3D32
> >         'data' type_id=3D213704 bits_offset=3D512
> >
> > Please tell me if I could provide any further information.
> >
> > You are of great help
> >
> > Thank you very much
> > Zhouyi
> Thanks for your help
>
> Or, can you teach me how to prepare an environment that can run
> "bpftool struct_ops register xxx.o" ;-)
> (A few words of description of OS version (Ubuntu/CentOS/Suse for etc)
> and example kernel .config is enough)
I invoke following commands, and it works:
cd tools/testing/selftests/bpf
find . -name vmlinux.h|xargs rm
make -j 20

put bpf_cubic.bpf.o to my virtual machine, and it works!
I don't know why

Thank you all!
Best Regards
Zhouyi
>
> I am an enthusiastic learner ;-)
>
> Thanks in advance
> Zhouyi
> > >