From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Quentin Monnet <quentin@isovalent.com>
Cc: Andrii Nakryiko <andrii@kernel.org>, bpf <bpf@vger.kernel.org>,
Networking <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v2 bpf-next 08/11] bpftool: add `gen object` command to perform BPF static linking
Date: Mon, 15 Mar 2021 22:16:37 -0700 [thread overview]
Message-ID: <CAEf4Bzag+Vx4uBEeeoVfU0gOmq=J70DCsr8Yr3Y=K257Ry1-kA@mail.gmail.com> (raw)
In-Reply-To: <af200ca7-5946-9df6-71ec-98042aecfa27@isovalent.com>
On Mon, Mar 15, 2021 at 2:24 AM Quentin Monnet <quentin@isovalent.com> wrote:
>
> 2021-03-13 11:35 UTC-0800 ~ Andrii Nakryiko <andrii@kernel.org>
> > Add `bpftool gen object <output-file> <input_file>...` command to statically
> > link multiple BPF ELF object files into a single output BPF ELF object file.
> >
> > Similarly to existing '*.o' convention, bpftool is establishing a '*.bpfo'
> > convention for statically-linked BPF object files. Both .o and .bpfo suffixes
> > will be stripped out during BPF skeleton generation to infer BPF object name.
> >
> > This patch also updates bash completions and man page. Man page gets a short
> > section on `gen object` command, but also updates the skeleton example to show
> > off workflow for BPF application with two .bpf.c files, compiled individually
> > with Clang, then resulting object files are linked together with `gen object`,
> > and then final object file is used to generate usable BPF skeleton. This
> > should help new users understand realistic workflow w.r.t. compiling
> > mutli-file BPF application.
> >
> > Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
> > ---
> > .../bpf/bpftool/Documentation/bpftool-gen.rst | 65 +++++++++++++++----
> > tools/bpf/bpftool/bash-completion/bpftool | 2 +-
> > tools/bpf/bpftool/gen.c | 49 +++++++++++++-
> > 3 files changed, 99 insertions(+), 17 deletions(-)
> >
> > diff --git a/tools/bpf/bpftool/Documentation/bpftool-gen.rst b/tools/bpf/bpftool/Documentation/bpftool-gen.rst
> > index 84cf0639696f..4cdce187c393 100644
> > --- a/tools/bpf/bpftool/Documentation/bpftool-gen.rst
> > +++ b/tools/bpf/bpftool/Documentation/bpftool-gen.rst
> > @@ -14,16 +14,37 @@ SYNOPSIS
> >
> > *OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] }
> >
> > - *COMMAND* := { **skeleton** | **help** }
> > + *COMMAND* := { **object** | **skeleton** | **help** }
> >
> > GEN COMMANDS
> > =============
> >
> > +| **bpftool** **gen object** *OUTPUT_FILE* *INPUT_FILE* [*INPUT_FILE*...]
> > | **bpftool** **gen skeleton** *FILE*
> > | **bpftool** **gen help**
> >
> > DESCRIPTION
> > ===========
> > + **bpftool gen object** *OUTPUT_FILE* *INPUT_FILE* [*INPUT_FILE*...]
> > + Statically link (combine) together one or more *INPUT_FILE*'s
> > + into a single resulting *OUTPUT_FILE*. All the files involed
>
> Typo: "involed"
>
> > + are BPF ELF object files.
> > +
> > + The rules of BPF static linking are mostly the same as for
> > + user-space object files, but in addition to combining data
> > + and instruction sections, .BTF and .BTF.ext (if present in
> > + any of the input files) data are combined together. .BTF
> > + data is deduplicated, so all the common types across
> > + *INPUT_FILE*'s will only be represented once in the resulting
> > + BTF information.
> > +
> > + BPF static linking allows to partition BPF source code into
> > + individually compiled files that are then linked into
> > + a single resulting BPF object file, which can be used to
> > + generated BPF skeleton (with **gen skeleton** command) or
> > + passed directly into **libbpf** (using **bpf_object__open()**
> > + family of APIs).
> > +
> > **bpftool gen skeleton** *FILE*
> > Generate BPF skeleton C header file for a given *FILE*.
> >
>
> > diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
> > index fdffbc64c65c..7ca23c58f2c0 100644
> > --- a/tools/bpf/bpftool/bash-completion/bpftool
> > +++ b/tools/bpf/bpftool/bash-completion/bpftool
> > @@ -981,7 +981,7 @@ _bpftool()
> > ;;
> > gen)
> > case $command in
> > - skeleton)
> > + object|skeleton)
> > _filedir
> > ;;
> > *)
>
> Suggesting the "object" keyword for completing "bpftool gen [tab]"
> is missing. It is just a few lines below:
>
> ------
> diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
> index fdffbc64c65c..223438e86932 100644
> --- a/tools/bpf/bpftool/bash-completion/bpftool
> +++ b/tools/bpf/bpftool/bash-completion/bpftool
> @@ -981,12 +981,12 @@ _bpftool()
> ;;
> gen)
> case $command in
> - skeleton)
> + object|skeleton)
> _filedir
> ;;
> *)
> [[ $prev == $object ]] && \
> - COMPREPLY=( $( compgen -W 'skeleton help' -- "$cur" ) )
> + COMPREPLY=( $( compgen -W 'object skeleton help' -- "$cur" ) )
> ;;
> esac
> ;;
> ------
>
> Looks good otherwise. Thanks for the documentation, it's great to
> have the example in the man page.
>
> Pending the two nits above are fixed:
> Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Thanks! I'll wait a bit for some more feedback on other patches and
will fix it in the next version (unless my other patches are perfect,
of course ;).
>
> Quentin
next prev parent reply other threads:[~2021-03-16 5:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-13 19:35 [PATCH v2 bpf-next 00/11] BPF static linking Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 01/11] libbpf: expose btf_type_by_id() internally Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 02/11] libbpf: generalize BTF and BTF.ext type ID and strings iteration Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 03/11] libbpf: rename internal memory-management helpers Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 04/11] libbpf: extract internal set-of-strings datastructure APIs Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 05/11] libbpf: add generic BTF type shallow copy API Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 06/11] libbpf: add BPF static linker APIs Andrii Nakryiko
2021-06-07 23:11 ` Tom Stellard
2021-06-08 0:25 ` Andrii Nakryiko
[not found] ` <b1bdf1df-e3a8-1ce8-fc33-4ab40b39fb06@redhat.com>
2021-06-08 2:41 ` Tom Stellard
2021-06-08 4:08 ` Andrii Nakryiko
2021-06-08 6:47 ` Yonghong Song
2021-06-09 3:44 ` Tom Stellard
2021-06-09 4:41 ` Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 07/11] libbpf: add BPF static linker BTF and BTF.ext support Andrii Nakryiko
2021-03-17 5:25 ` Alexei Starovoitov
2021-03-17 22:10 ` Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 08/11] bpftool: add `gen object` command to perform BPF static linking Andrii Nakryiko
2021-03-15 9:24 ` Quentin Monnet
2021-03-16 5:16 ` Andrii Nakryiko [this message]
2021-03-13 19:35 ` [PATCH v2 bpf-next 09/11] selftests/bpf: re-generate vmlinux.h and BPF skeletons if bpftool changed Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 10/11] selftests/bpf: pass all BPF .o's through BPF static linker Andrii Nakryiko
2021-03-17 5:34 ` Alexei Starovoitov
2021-03-17 20:47 ` Andrii Nakryiko
2021-03-17 21:00 ` Alexei Starovoitov
2021-03-17 21:22 ` Andrii Nakryiko
2021-03-13 19:35 ` [PATCH v2 bpf-next 11/11] selftests/bpf: add multi-file statically linked BPF object file test Andrii Nakryiko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAEf4Bzag+Vx4uBEeeoVfU0gOmq=J70DCsr8Yr3Y=K257Ry1-kA@mail.gmail.com' \
--to=andrii.nakryiko@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@fb.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kernel-team@fb.com \
--cc=netdev@vger.kernel.org \
--cc=quentin@isovalent.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).