From: Alan Maguire <almagui@kernel.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Quentin Monnet <qmo@kernel.org>
Cc: bpf@vger.kernel.org, Alan Maguire <alan.maguire@oracle.com>,
Cupertino Miranda <cupertino.miranda@oracle.com>,
David Faust <david.faust@oracle.com>,
Ian Rogers <irogers@google.com>,
"Jose E . Marchesi" <jose.marchesi@oracle.com>,
Vineet Gupta <vineet.gupta@linux.dev>,
Yonghong Song <yonghong.song@linux.dev>
Subject: Re: [PATCH bpf-next v1 1/8] bpftool: Dump C from a detached BTF copy
Date: Fri, 16 Oct 2026 10:44:49 +0100 [thread overview]
Message-ID: <f59b81f4-74e6-46c5-bc0a-ad12ce2ecb53@kernel.org> (raw)
In-Reply-To: <DM5V83GMXC13.B0KDKO805LCG@gmail.com>
On 10/16/26 2:18 AM, Alexei Starovoitov wrote:
> On Thu, Oct 15, 2026 at 05:00 PM Ihor Solodrai <ihor.solodrai@linux.dev> wrote:
>> Modifying the parsed BTF fails for some valid input: libbpf refuses to
>> modify BTF whose header carries unknown nonzero extension bytes, so
>> such a dump would stop with -EOPNOTSUPP.
>>
>> Dump from a flat copy built with btf__add_type(), which only requires
>> the destination to be modifiable.
>
> can we do btf__new_empty_split(btf) and add decl attrs there
> instead of copying all types ?
> It fails on such BTF only because btf__add_str() does
> btf__find_str(base) and that calls btf_ensure_modifiable(base).
> The lookup shouldn't need it.
+1 on using split BTF for new decl tags; even in the case of module
BTF we can use multi-split BTF to cover decl tags for vmlinux and
module BTF I think.
next prev parent reply other threads:[~2026-10-16 9:44 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-16 0:00 [PATCH bpf-next v1 0/8] bpftool: Per-record CO-RE attributes in the C dump Ihor Solodrai
2026-10-16 0:00 ` [PATCH bpf-next v1 1/8] bpftool: Dump C from a detached BTF copy Ihor Solodrai
2026-10-16 1:18 ` Alexei Starovoitov
2026-10-16 9:44 ` Alan Maguire [this message]
2026-10-16 9:25 ` Alan Maguire
2026-10-16 0:00 ` [PATCH bpf-next v1 2/8] selftests/bpf: Cover unknown BTF header-extension bytes in btf dump Ihor Solodrai
2026-10-16 0:00 ` [PATCH bpf-next v1 3/8] bpftool: Apply __bpf_core_pai per record on BTF dump Ihor Solodrai
2026-10-16 0:39 ` bot+bpf-ci
2026-10-16 1:17 ` Alexei Starovoitov
2026-10-16 0:00 ` [PATCH bpf-next v1 4/8] bpftool: Skip __bpf_core_pai on verifier-rewritten context types Ihor Solodrai
2026-10-16 0:00 ` [PATCH bpf-next v1 5/8] bpftool: Emit __bpf_core_pso " Ihor Solodrai
2026-10-16 1:27 ` Alexei Starovoitov
2026-10-16 5:49 ` Ihor Solodrai
2026-10-16 0:00 ` [PATCH bpf-next v1 6/8] selftests/bpf: Cover record attributes in bpftool BTF dumps Ihor Solodrai
2026-10-16 0:00 ` [PATCH bpf-next v1 7/8] selftests/bpf: Cover context and socket accesses through vmlinux.h Ihor Solodrai
2026-10-16 0:00 ` [PATCH bpf-next v1 8/8] bpftool: Document __bpf_core_pai and __bpf_core_pso Ihor Solodrai
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