On Thu, Mar 09, 2023 at 02:49:30PM -0800, Sreevani Sreejith wrote:
> From: Sreevani <ssreevani@xxxxxxxx>
>
> Summary: Document that provides an overview of libbpf features for BPF
> application development.
>
> Reviewers:
>
> Subscribers:
Please remove the boilerplate above. The summary should become patch
description.
> +======
> libbpf
> ======
Why did you promote the heading above to title heading?
> diff --git a/Documentation/bpf/libbpf/libbpf_overview.rst b/Documentation/bpf/libbpf/libbpf_overview.rst
> new file mode 100644
> index 000000000000..549469aa2d3b
> --- /dev/null
> +++ b/Documentation/bpf/libbpf/libbpf_overview.rst
> @@ -0,0 +1,238 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +.._libbpf-overview-label:
Missing space before label name. Or should the label name be
"_libbpf-overview"?
> +#################################
> +BPF App Lifecycle and libbpf APIs
> +#################################
> <snipped> ...
> +########################
> +BPF Object Skeleton File
> +########################
> <snipped> ...
> +---------------------------------------
> +Other Advantages of Using Skeleton File
> +---------------------------------------
> +
> <snipped> ...
> +###########
> +BPF Helpers
> +###########
> <snipped> ...
> +#########################################
> +BPF CO-RE (Compile Once – Run Everywhere)
> +#########################################
> <snipped> ...
See the bottom.
> +You can generate the BTF information for the running kernel with the following
> +command:
> +
> +::
> +
> +$ bpftool btf dump file /sys/kernel/btf/vmlinux format c > vmlinux.h
My htmldocs build renders the code block above fine, but IMO the
convention here is to indent it.
> +The following code snippet shows how to read the parent field of a kernel
> +``task_struct`` using BPF CO-RE and libbf. The basic helper to read a field in a
> +CO-RE relocatable manner is ``bpf_core_read(dst, sz, src)``, which will read
> +``sz`` bytes from the field referenced by ``src`` into the memory pointed to by
> +``dst``.
> +
> + .. code-block:: C
> + :emphasize-lines: 6
> +
> + //...
> + struct task_struct *task = (void *)bpf_get_current_task();
> + struct task_struct *parent_task;
> + int err;
> +
> + err = bpf_core_read(&parent_task, sizeof(void *), &task->parent);
> + if (err) {
> + /* handle error */
> + }
> +
> + /* parent_task contains the value of task->parent pointer */
I guess :linenos: option also helps locating the highlighted line, right?
> +###########################
> +Getting Started with libbpf
> +###########################
> <snipped> ...
> +###############
> +libbpf and Rust
> +###############
> <snipped> ...
> +########################
> +Additional Documentation
> +########################
For section headings above, I'd like to strip the overline. Yet,
Sphinx is smart when discriminating headings based on underline/overline
character.
Thanks.
--
An old man doll... just what I always wanted! - Clara
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