btf__parse_split
btf = btf__parse_split(*argv, base ?: base_btf);
btf = btf__parse_split(obj->btf_path ?: obj->path, base_btf);
return btf__parse_split(path, vmlinux_btf);
LIBBPF_API struct btf *btf__parse_split(const char *path, struct btf *base_btf);
btf1 = btf__parse_split("/sys/kernel/btf/bpf_testmod", vmlinux_btf);
btf5 = btf__parse_split(split_btf_file, btf4);
btf6 = btf__parse_split(multisplit_btf_file, btf5);