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diff --git a/README.md b/README.md new file mode 100644 index 0000000..9861b16 --- /dev/null +++ b/README.md @@ -0,0 +1,189 @@ +<picture> + <source media="(prefers-color-scheme: dark)" srcset="assets/libbpf-logo-sideways-darkbg.png" width="40%"> + <img src="assets/libbpf-logo-sideways.png" width="40%"> +</picture> + +libbpf +[](https://github.com/libbpf/libbpf/actions/workflows/test.yml) +[](https://scan.coverity.com/projects/libbpf) +[](https://github.com/libbpf/libbpf/actions?query=workflow%3ACodeQL+branch%3Amaster) +[](https://oss-fuzz-build-logs.storage.googleapis.com/index.html#libbpf) +[](https://libbpf.readthedocs.io/en/latest/) +====== + +**This is the official home of the libbpf library.** + +*Please use this Github repository for building and packaging libbpf +and when using it in your projects through Git submodule.* + +Libbpf *authoritative source code* is developed as part of [bpf-next Linux source +tree](https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next) under +`tools/lib/bpf` subdirectory and is periodically synced to Github. As such, all the +libbpf changes should be sent to [BPF mailing list](http://vger.kernel.org/vger-lists.html#bpf), +please don't open PRs here unless you are changing Github-specific parts of libbpf +(e.g., Github-specific Makefile). + +Libbpf and general BPF usage questions +====================================== + +Libbpf documentation can be found [here](https://libbpf.readthedocs.io/en/latest/api.html). +It's an ongoing effort and has ways to go, but please take a look and consider contributing as well. + +Please check out [libbpf-bootstrap](https://github.com/libbpf/libbpf-bootstrap) +and [the companion blog post](https://nakryiko.com/posts/libbpf-bootstrap/) for +the examples of building BPF applications with libbpf. +[libbpf-tools](https://github.com/iovisor/bcc/tree/master/libbpf-tools) are also +a good source of the real-world libbpf-based tracing tools. + +See also ["BPF CO-RE reference guide"](https://nakryiko.com/posts/bpf-core-reference-guide/) +for the coverage of practical aspects of building BPF CO-RE applications and +["BPF CO-RE"](https://nakryiko.com/posts/bpf-portability-and-co-re/) for +general introduction into BPF portability issues and BPF CO-RE origins. + +All general BPF questions, including kernel functionality, libbpf APIs and +their application, should be sent to bpf@vger.kernel.org mailing list. You can +subscribe to it [here](http://vger.kernel.org/vger-lists.html#bpf) and search +its archive [here](https://lore.kernel.org/bpf/). Please search the archive +before asking new questions. It very well might be that this was already +addressed or answered before. + +bpf@vger.kernel.org is monitored by many more people and they will happily try +to help you with whatever issue you have. This repository's PRs and issues +should be opened only for dealing with issues pertaining to specific way this +libbpf mirror repo is set up and organized. + +Building libbpf +=============== +libelf is an internal dependency of libbpf and thus it is required to link +against and must be installed on the system for applications to work. +pkg-config is used by default to find libelf, and the program called can be +overridden with `PKG_CONFIG`. + +If using `pkg-config` at build time is not desired, it can be disabled by +setting `NO_PKG_CONFIG=1` when calling make. + +To build both static libbpf.a and shared libbpf.so: +```bash +$ cd src +$ make +``` + +To build only static libbpf.a library in directory +build/ and install them together with libbpf headers in a staging directory +root/: +```bash +$ cd src +$ mkdir build root +$ BUILD_STATIC_ONLY=y OBJDIR=build DESTDIR=root make install +``` + +To build both static libbpf.a and shared libbpf.so against a custom libelf +dependency installed in /build/root/ and install them together with libbpf +headers in a build directory /build/root/: +```bash +$ cd src +$ PKG_CONFIG_PATH=/build/root/lib64/pkgconfig DESTDIR=/build/root make install +``` + +BPF CO-RE (Compile Once – Run Everywhere) +========================================= + +Libbpf supports building BPF CO-RE-enabled applications, which, in contrast to +[BCC](https://github.com/iovisor/bcc/), do not require Clang/LLVM runtime +being deployed to target servers and doesn't rely on kernel-devel headers +being available. + +It does rely on kernel to be built with [BTF type +information](https://www.kernel.org/doc/html/latest/bpf/btf.html), though. +Some major Linux distributions come with kernel BTF already built in: + - Fedora 31+ + - RHEL 8.2+ + - OpenSUSE Tumbleweed (in the next release, as of 2020-06-04) + - Arch Linux (from kernel 5.7.1.arch1-1) + - Manjaro (from kernel 5.4 if compiled after 2021-06-18) + - Ubuntu 20.10 + - Debian 11 (amd64/arm64) + +If your kernel doesn't come with BTF built-in, you'll need to build custom +kernel. You'll need: + - `pahole` 1.16+ tool (part of `dwarves` package), which performs DWARF to + BTF conversion; + - kernel built with `CONFIG_DEBUG_INFO_BTF=y` option; + - you can check if your kernel has BTF built-in by looking for + `/sys/kernel/btf/vmlinux` file: + +```shell +$ ls -la /sys/kernel/btf/vmlinux +-r--r--r--. 1 root root 3541561 Jun 2 18:16 /sys/kernel/btf/vmlinux +``` + +To develop and build BPF programs, you'll need Clang/LLVM 10+. The following +distributions have Clang/LLVM 10+ packaged by default: + - Fedora 32+ + - Ubuntu 20.04+ + - Arch Linux + - Ubuntu 20.10 (LLVM 11) + - Debian 11 (LLVM 11) + - Alpine 3.13+ + +Otherwise, please make sure to update it on your system. + +The following resources are useful to understand what BPF CO-RE is and how to +use it: +- [BPF CO-RE reference guide](https://nakryiko.com/posts/bpf-core-reference-guide/) +- [BPF Portability and CO-RE](https://nakryiko.com/posts/bpf-portability-and-co-re/) +- [HOWTO: BCC to libbpf conversion](https://nakryiko.com/posts/bcc-to-libbpf-howto-guide/) +- [libbpf-tools in BCC repo](https://github.com/iovisor/bcc/tree/master/libbpf-tools) + contain lots of real-world tools converted from BCC to BPF CO-RE. Consider + converting some more to both contribute to the BPF community and gain some + more experience with it. + +Distributions +============= + +Distributions packaging libbpf from this mirror: + - [Fedora](https://src.fedoraproject.org/rpms/libbpf) + - [Gentoo](https://packages.gentoo.org/packages/dev-libs/libbpf) + - [Debian](https://packages.debian.org/source/sid/libbpf) + - [Arch](https://archlinux.org/packages/core/x86_64/libbpf/) + - [Ubuntu](https://packages.ubuntu.com/source/impish/libbpf) + - [Alpine](https://pkgs.alpinelinux.org/packages?name=libbpf) + +Benefits of packaging from the mirror over packaging from kernel sources: + - Consistent versioning across distributions. + - No ties to any specific kernel, transparent handling of older kernels. + Libbpf is designed to be kernel-agnostic and work across multitude of + kernel versions. It has built-in mechanisms to gracefully handle older + kernels, that are missing some of the features, by working around or + gracefully degrading functionality. Thus libbpf is not tied to a specific + kernel version and can/should be packaged and versioned independently. + - Continuous integration testing via + [GitHub Actions](https://github.com/libbpf/libbpf/actions). + - Static code analysis via [LGTM](https://lgtm.com/projects/g/libbpf/libbpf) + and [Coverity](https://scan.coverity.com/projects/libbpf). + +Package dependencies of libbpf, package names may vary across distros: + - zlib + - libelf + +[](https://repology.org/project/libbpf/versions) + + +bpf-next to Github sync +======================= + +All the gory details of syncing can be found in `scripts/sync-kernel.sh` +script. + +Some header files in this repo (`include/linux/*.h`) are reduced versions of +their counterpart files at +[bpf-next](https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/)'s +`tools/include/linux/*.h` to make compilation successful. + +License +======= + +This work is dual-licensed under BSD 2-clause license and GNU LGPL v2.1 license. +You can choose between one of them if you use this work. + +`SPDX-License-Identifier: BSD-2-Clause OR LGPL-2.1` |