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From:   Larysa Zaremba <larysa.zaremba@intel.com>
To:     andrii.nakryiko@gmail.com
Cc:     alexandr.lobakin@intel.com, andrii@kernel.org, ast@kernel.org,
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        maciej.fijalkowski@intel.com, netdev@vger.kernel.org,
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Subject: Re: [PATCH] bpftool: Use sysfs vmlinux when dumping BTF by ID
Date:   Thu,  5 May 2022 15:56:26 +0200
Message-Id: <20220505135626.137133-1-larysa.zaremba@intel.com>
In-Reply-To: <CAEf4BzZRioYpgsUFP1TLsqtjtvA3WLyuWjSyq12ctUoMqkUorg@mail.gmail.com>
References: <CAEf4BzZRioYpgsUFP1TLsqtjtvA3WLyuWjSyq12ctUoMqkUorg@mail.gmail.com>
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On Thu, 28 Apr 2022 21:58:58 -0700 Andrii Nakryiko <andrii@kernel.org> wrote:
> On Thu, Apr 28, 2022 at 4:17 AM Larysa Zaremba <larysa.zaremba@intel.com> wrote:
> >
> > Currently, dumping almost all BTFs specified by id requires
>
> It should and will work only for kernel modules. It won't and
> shouldn't work for BTFs coming from BPF programs. We shouldn't blindly
> guess and substitute vmlinux BTF as base BTF, let's fetch
> bpf_btf_info, check that BTF is from kernel and is not vmlinux, and
> only in such case substitute vmlinux BTF as base BTF.

I agree, this is taken into account in v2

> > using the -B option to pass the base BTF. For most cases
> > the vmlinux BTF sysfs path should work.
> >
> > This patch simplifies dumping by ID usage by attempting to
> > use vmlinux BTF from sysfs, if the first try of loading BTF by ID
> > fails with certain conditions.
> >
> > Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
> > Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
> > ---
> >  tools/bpf/bpftool/btf.c | 35 ++++++++++++++++++++++++++---------
> >  1 file changed, 26 insertions(+), 9 deletions(-)
> >

Best Regards,
Larysa Zaremba