Re: [PATCH bpf-next 1/1] bpf: btf: add btf=off boot parameter to disable and free vmlinux BTF

[Wang, Jay]

> Consider using Alan's approach and support CONFIG_DEBUG_INFO_BTF=m

Thanks for the suggestion. We’ll explore how we can make CONFIG_DEBUG_INFO_BTF=m supportable and may post a v2 patch later.

Best,
Jay

On 9/16/26, 6:56 PM, "Alexei Starovoitov" <alexei.starovoitov@xxxxxxxxx <mailto:alexei.starovoitov@xxxxxxxxx>> wrote:


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On Thu, Sep 17, 2026 at 12:02 AM Jay Wang <wanjay@xxxxxxxxxx <mailto:wanjay@xxxxxxxxxx>> wrote:
>
> Add a "btf=off" early boot parameter, similar to the existing "selinux=0"
> parameter, so users who do not want BTF can turn it off at boot; the
> section is then freed to save memory.


tbh I'm not excited about btf=off. BTF is not debug info anymore.
sched_ext, bpf-lsm (systemd uses it), hid-bpf, most of bcc/bpftrace
quietly stop working, and we'll be the ones triaging "libbpf: failed
to find valid kernel BTF" reports from people who copy-pasted a
"save 5MB" tuning guide.
This needs more thought.


> .../admin-guide/kernel-parameters.txt | 14 +++
> arch/arm64/mm/mmu.c | 108 +++++++++++++++++-
> arch/x86/mm/init_64.c | 30 +++++
> arch/x86/mm/pat/set_memory.c | 28 ++++-
> include/linux/btf.h | 9 ++
> kernel/bpf/btf.c | 51 ++++++++-
> kernel/bpf/sysfs_btf.c
| 7 ++
> kernel/bpf/verifier.c | 2 +-


This doesn't apply to bpf-next.
Consider using Alan's approach and support CONFIG_DEBUG_INFO_BTF=m


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