On Fri, May 13, 2022 at 8:14 PM Yonghong Song <yhs@xxxxxx> wrote:
>
> Add BTF_KIND_ENUM64 documentation in btf.rst.
> Also fixed a typo for section number for BTF_KIND_TYPE_TAG
> from 2.2.17 to 2.2.18.
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
LGTM, but see pedantic note below
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> Documentation/bpf/btf.rst | 34 +++++++++++++++++++++++++++++-----
> 1 file changed, 29 insertions(+), 5 deletions(-)
>
[...]
> +2.2.19 BTF_KIND_ENUM64
> +~~~~~~~~~~~~~~~~~~~~~~
> +
> +``struct btf_type`` encoding requirement:
> + * ``name_off``: 0 or offset to a valid C identifier
> + * ``info.kind_flag``: 0 for unsigned, 1 for signed
> + * ``info.kind``: BTF_KIND_ENUM64
> + * ``info.vlen``: number of enum values
> + * ``size``: 1/2/4/8
> +
> +``btf_type`` is followed by ``info.vlen`` number of ``struct btf_enum64``.::
> +
> + struct btf_enum64 {
> + __u32 name_off;
> + __u32 val_lo32;
> + __u32 val_hi32;
> + };
> +
> +The ``btf_enum64`` encoding:
> + * ``name_off``: offset to a valid C identifier
> + * ``val_lo32``: lower 32-bit value for a 64-bit value
> + * ``val_hi32``: high 32-bit value for a 64-bit value
> +
I presume if size is < 8 then val_hi32 will be sign-extended (i.e.,
0xffffffff for signed enum and negative enumerator values, 0
otherwise), right? Should it be specified here?
> 3. BTF Kernel API
> =================
>
> --
> 2.30.2
>
