From: Yonghong Song <yhs@fb.com>
To: Ilya Leoshkevich <iii@linux.ibm.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>, <bpf@vger.kernel.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>
Subject: Re: [PATCH v2 bpf-next 6/6] bpf: Document BTF_KIND_FLOAT in btf.rst
Date: Thu, 18 Feb 2021 21:41:11 -0800 [thread overview]
Message-ID: <8e1f764e-856d-4f20-96d5-49c83f692d72@fb.com> (raw)
In-Reply-To: <20210219022543.20893-7-iii@linux.ibm.com>
On 2/18/21 6:25 PM, Ilya Leoshkevich wrote:
> Also document the expansion of the kind bitfield.
>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
> Documentation/bpf/btf.rst | 17 +++++++++++++++--
> 1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
> index 44dc789de2b4..4f25c992d442 100644
> --- a/Documentation/bpf/btf.rst
> +++ b/Documentation/bpf/btf.rst
> @@ -84,6 +84,7 @@ sequentially and type id is assigned to each recognized type starting from id
> #define BTF_KIND_FUNC_PROTO 13 /* Function Proto */
> #define BTF_KIND_VAR 14 /* Variable */
> #define BTF_KIND_DATASEC 15 /* Section */
> + #define BTF_KIND_FLOAT 16 /* Floating point */
>
> Note that the type section encodes debug info, not just pure types.
> ``BTF_KIND_FUNC`` is not a type, and it represents a defined subprogram.
> @@ -95,8 +96,8 @@ Each type contains the following common data::
> /* "info" bits arrangement
> * bits 0-15: vlen (e.g. # of struct's members)
> * bits 16-23: unused
> - * bits 24-27: kind (e.g. int, ptr, array...etc)
> - * bits 28-30: unused
> + * bits 24-28: kind (e.g. int, ptr, array...etc)
> + * bits 29-30: unused
> * bit 31: kind_flag, currently used by
> * struct, union and fwd
> */
> @@ -452,6 +453,18 @@ map definition.
> * ``offset``: the in-section offset of the variable
> * ``size``: the size of the variable in bytes
>
> +2.2.16 BTF_KIND_FLOAT
> +~~~~~~~~~~~~~~~~~~~~~
> +
> +``struct btf_type`` encoding requirement:
> + * ``name_off``: any valid offset
> + * ``info.kind_flag``: 0
> + * ``info.kind``: BTF_KIND_FLOAT
> + * ``info.vlen``: 0
> + * ``size``: the size of the float type in bytes.
I would be good to specify the allowed size in bytes 2, multiple of 4.
currently we do not have a maximum value, maybe 128. have a float type
something like 2^10 seems strange.
> +
> +No additional type data follow ``btf_type``.
> +
> 3. BTF Kernel API
> *****************
>
>
next prev parent reply other threads:[~2021-02-19 5:42 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-19 2:25 [PATCH v2 bpf-next 0/6] Add BTF_KIND_FLOAT support Ilya Leoshkevich
2021-02-19 2:25 ` [PATCH v2 bpf-next 1/6] bpf: Add BTF_KIND_FLOAT to uapi Ilya Leoshkevich
2021-02-19 2:25 ` [PATCH v2 bpf-next 2/6] libbpf: Add BTF_KIND_FLOAT support Ilya Leoshkevich
2021-02-19 4:22 ` Yonghong Song
2021-02-19 23:01 ` Ilya Leoshkevich
2021-02-19 23:35 ` Yonghong Song
2021-02-19 23:43 ` Ilya Leoshkevich
2021-02-19 2:25 ` [PATCH v2 bpf-next 3/6] tools/bpftool: " Ilya Leoshkevich
2021-02-19 2:25 ` [PATCH v2 bpf-next 4/6] bpf: " Ilya Leoshkevich
2021-02-19 4:04 ` kernel test robot
2021-02-19 4:13 ` kernel test robot
2021-02-19 2:25 ` [PATCH v2 bpf-next 5/6] selftest/bpf: Add BTF_KIND_FLOAT tests Ilya Leoshkevich
2021-02-19 5:38 ` Yonghong Song
2021-02-19 5:44 ` Yonghong Song
2021-02-19 2:25 ` [PATCH v2 bpf-next 6/6] bpf: Document BTF_KIND_FLOAT in btf.rst Ilya Leoshkevich
2021-02-19 5:41 ` Yonghong Song [this message]
2021-02-19 13:00 ` Ilya Leoshkevich
2021-02-19 15:26 ` Yonghong Song
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