From: sashiko-bot@kernel.org
To: "Jay Wang" <wanjay@amazon.com>
Cc: linux-modules@vger.kernel.org, dmitry.torokhov@gmail.com,
linux-perf-users@vger.kernel.org,
linux-trace-kernel@vger.kernel.org, sched-ext@lists.linux.dev,
gary@garyguo.net, "Petr Pavlu" <petr.pavlu@suse.com>,
bpf@vger.kernel.org, ojeda@kernel.org,
linux-input@vger.kernel.org
Subject: Re: [PATCH bpf-next v4 04/12] bpf: take the vmlinux BTF from the btf_vmlinux module
Date: Fri, 02 Oct 2026 09:14:14 +0000 [thread overview]
Message-ID: <20261002091414.A81FF1F00893@smtp.kernel.org> (raw)
In-Reply-To: <20261001225214.12351-5-wanjay@amazon.com>
> Add the runtime side of delivering the vmlinux BTF as a module: with
> CONFIG_DEBUG_INFO_BTF=m the BTF is carried by a module named btf_vmlinux
> and installed by the BTF module notifier when it loads. Nothing in this
> patch is reachable yet: CONFIG_DEBUG_INFO_BTF is still a bool and every
> new path is under IS_MODULE(CONFIG_DEBUG_INFO_BTF); the kbuild side and
> the Kconfig change follow.
>
> With CONFIG_DEBUG_INFO_BTF=y the vmlinux BTF, 5.4 MiB on x86-64 with a
> distribution config, is part of the kernel image and resident from boot
> whether anything uses it or not. Most systems never do. Carrying it in
> a module that is loaded on first use makes the memory a cost of using
> BTF rather than of having a kernel that supports it.
>
> btf_vmlinux_data() hands out the raw vmlinux BTF: from __start_BTF with
> =y, or with =m from a vmalloc_user() copy that the notifier makes when
> [ ... ]
> maps the probed file. Before the BTF is loaded mmap() fails, and libbpf,
> which tries mmap() first, falls back to read(); afterwards it maps the
> vmalloc_user() copy with remap_vmalloc_range().
>
> Signed-off-by: Jay Wang <wanjay@amazon.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261001225214.12351-1-wanjay@amazon.com?part=4
next prev parent reply other threads:[~2026-10-02 9:14 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-01 22:52 [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory Jay Wang
2026-10-01 22:52 ` [PATCH bpf-next v4 01/12] bpf: pass the vmlinux BTF to btf_parse_module() and let it adopt the data Jay Wang
2026-10-02 9:14 ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 02/12] bpf: split the kfunc, dtor kfunc and struct_ops registration bodies Jay Wang
2026-10-02 9:14 ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 03/12] bpf: fetch the vmlinux BTF where kernel types enter a program Jay Wang
2026-10-02 9:14 ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 04/12] bpf: take the vmlinux BTF from the btf_vmlinux module Jay Wang
2026-10-01 23:45 ` bot+bpf-ci
2026-10-02 9:14 ` sashiko-bot [this message]
2026-10-02 11:48 ` Alexei Starovoitov
2026-10-01 22:52 ` [PATCH bpf-next v4 05/12] bpf, tracing: load the vmlinux BTF where tracefs and bpffs requests start Jay Wang
2026-10-02 9:14 ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 06/12] bpf: defer vmlinux kfunc and struct_ops registrations Jay Wang
2026-10-02 9:14 ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 07/12] bpf: keep module BTF until the vmlinux BTF is available Jay Wang
2026-10-01 23:45 ` bot+bpf-ci
2026-10-02 9:14 ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 08/12] bpf: expose deferred .BTF.base module BTF in sysfs from module load Jay Wang
2026-10-02 9:14 ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 09/12] bpf, trace, net: prepare CONFIG_DEBUG_INFO_BTF checks for a tristate Jay Wang
2026-10-02 9:14 ` sashiko-bot
2026-10-05 11:32 ` Nicolas Schier
2026-10-01 22:52 ` [PATCH bpf-next v4 10/12] resolve_btfids: add --btf_link to fill in .BTF.link records Jay Wang
2026-10-01 23:29 ` bot+bpf-ci
2026-10-02 9:14 ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 11/12] tools, samples: take the vmlinux BTF from vmlinux.unstripped first Jay Wang
2026-10-02 9:14 ` sashiko-bot
2026-10-05 11:17 ` Nicolas Schier
2026-10-01 22:52 ` [PATCH bpf-next v4 12/12] kbuild, bpf: allow building the vmlinux BTF as a module Jay Wang
2026-10-02 9:14 ` sashiko-bot
2026-10-02 9:47 ` Alan Maguire
2026-10-02 4:36 ` [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory Ihor Solodrai
2026-10-02 7:34 ` Jay Wang
2026-10-02 10:05 ` Alan Maguire
2026-10-02 20:58 ` Ihor Solodrai
2026-10-03 6:38 ` Alexei Starovoitov
2026-10-03 11:45 ` Alan Maguire
2026-10-03 12:19 ` Alexei Starovoitov
2026-10-04 22:21 ` Jay Wang
2026-10-05 19:01 ` Ihor Solodrai
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