Re: [RFC] btf: split core BTF parsing out of BPF subsystem into kernel/btf/

[Alan Maguire]

On 25/03/2026 01:18, Sasha Levin wrote:
> Move BTF type format parsing and inspection code out of the BPF
> subsystem into its own kernel/bf/ directory, separating core BTF
> functionality from BPF-specific extensions.
> 
> CONFIG_DEBUG_INFO_BTF currently depends on CONFIG_BPF_SYSCALL, which
> prevents embedded, automotive, and safety-critical environments from
> using BTF. These platforms often disable BPF for security and size
> reasons but would benefit from BTF type information for crash
> diagnostics and debugging.
> 

I had a go at a refactor in this area too, and it's pretty tricky. How about
we start with a smaller goal; making /sys/kernel/btf available to userspace
on systems without CONFIG_BPF_SYSCALL? This would just involve a small refactor 
of the BTF module-related stuff in kernel/bpf/btf.c, moving it to btf_module.c 
or similar say. No need to split out BTF parsing APIs from those actively used in 
validating BPF etc, since a non-BPF_SYSCALL system would not need to parse BTF 
in the kernel (just make it available in sysfs.