* Re: [PATCH bpf-next v3 9/9] kbuild, bpf: allow building the vmlinux BTF as a module
[not found] <6e565a3c5689de1d5ba05904e3d7f477373bca8e10be75fea4b6adc048ab6ac4@mail.kernel.org>
@ 2026-10-01 23:53 ` Jay Wang
0 siblings, 0 replies; only message in thread
From: Jay Wang @ 2026-10-01 23:53 UTC (permalink / raw)
To: bot+bpf-ci, bpf, ast, daniel, andrii, eddyz87, memxor
Cc: alan.maguire, martin.lau, yonghong.song, jolsa, nathan, nsc,
linux-kbuild, mcgrof, petr.pavlu, samitolvanen, linux-modules,
ojeda, rust-for-linux, arnd, linux-kernel, abuehaze, doebel,
mpohlack, jay.wang.upstream, martin.lau, mason, ihor.solodrai,
rostedt, mhiramat, linux-trace-kernel
All three are addressed in v4:
https://lore.kernel.org/bpf/20261001225214.12351-1-wanjay@amazon.com/
- The ftrace argument printer is a real problem: it can run from
ftrace_dump() with interrupts disabled. print_function_args() now
only prints the arguments if the vmlinux BTF is already loaded
(bpf_peek_btf_vmlinux(), patch 5/12), like bpf_snprintf_btf(); in v4
the lookup it uses would not load the BTF anyway. Tested with
func-args on and sysrq-z as the first thing touching BTF after boot,
on a kernel with CONFIG_DEBUG_ATOMIC_SLEEP.
- The opening of the changelog now names the exceptions: BPF_PRELOAD,
users of kernel types that run before btf_vmlinux.ko can be loaded,
and code that assumes the vmlinux BTF has id 1.
- btf.rst now lists the requests that load the BTF, including struct_ops
maps, kprobe events with BTF arguments, tracepoint btf_ids files and
bpffs delegate_* options.
PROBE_EVENTS_BTF_ARGS and FUNCTION_TRACE_ARGS do stay enabled with =m,
which is intended: creating a probe with BTF arguments loads the BTF, in
process context, and the argument printer uses it once it is there.
Jay
^ permalink raw reply [flat|nested] only message in thread