Clarify where the BTF_KIND_TYPE_TAG gets encoded in the type chain, so applications and kernel can properly parse them. Signed-off-by: Yonghong Song <yhs@xxxxxx> --- Documentation/bpf/btf.rst | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst index ab08852e53ae..7940da9bc6c1 100644 --- a/Documentation/bpf/btf.rst +++ b/Documentation/bpf/btf.rst @@ -503,6 +503,19 @@ valid index (starting from 0) pointing to a member or an argument. * ``info.vlen``: 0 * ``type``: the type with ``btf_type_tag`` attribute +Currently, ``BTF_KIND_TYPE_TAG`` is only emitted for pointer types. +It has the following btf type chain: +:: + + ptr -> [type_tag]* + -> [const | volatile | restrict | typedef]* + -> base_type + +Basically, a pointer type points to zero or more +type_tag, then zero or more const/volatile/restrict/typedef +and finally the base type. The base type is one of +int, ptr, array, struct, union, enum, func_proto and float types. + 3. BTF Kernel API ================= -- 2.30.2
