Hi, Should BPF code be using UAPI types such as __u32 or is it considered acceptable to use kernel types such as u32? I ask because the helper definitions that come from libbpf use the UAPI __u32 style types, but the bpf-helpers(7) man page refers to the kernel u32 style types. As I understand it, u32 et al are kernel internal type definitions that should not leak into userspace which I believe extends to BPF code. In order to use a kernel internal type, the BPF programmer would need to define it themselves, or use a BTF generated vmlinux.h? Please correct me if I am wrong, or oversimplifying things. I think it would be useful to include a statement about UAPI types and usage in BPF code somewhere in the documentation. Once I have an answer to the question above, I am happy to work on a contribution to the documentation. A follow-on question is how to make things consistent across the UAPI header files and the bpf-helpers(7) documentation.
