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This is the official home of the libbpf library.

Please use this Github repository for building and packaging libbpfand when using it in your projects through Git submodule.

Libbpfauthoritative source code is developed as part ofbpf-next Linux sourcetree undertools/lib/bpf subdirectory and is periodically synced to Github. As such, all thelibbpf changes should be sent toBPF mailing list,please don't open PRs here unless you are changing Github-specific parts of libbpf(e.g., Github-specific Makefile).

Libbpf documentation can be foundhere.It's an ongoing effort and has ways to go, but please take a look and consider contributing as well.

Please check outlibbpf-bootstrapandthe companion blog post forthe examples of building BPF applications with libbpf.libbpf-tools are alsoa good source of the real-world libbpf-based tracing tools.

See also"BPF CO-RE reference guide"for the coverage of practical aspects of building BPF CO-RE applications and"BPF CO-RE" forgeneral introduction into BPF portability issues and BPF CO-RE origins.

All general BPF questions, including kernel functionality, libbpf APIs andtheir application, should be sent tobpf@vger.kernel.org mailing list. You cansubscribe to ithere and searchits archivehere. Please search the archivebefore asking new questions. It very well might be that this was alreadyaddressed or answered before.

bpf@vger.kernel.org is monitored by many more people and they will happily tryto help you with whatever issue you have. This repository's PRs and issuesshould be opened only for dealing with issues pertaining to specific way thislibbpf mirror repo is set up and organized.

libelf is an internal dependency of libbpf and thus it is required to linkagainst 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 beoverridden withPKG_CONFIG.

If usingpkg-config at build time is not desired, it can be disabled bysettingNO_PKG_CONFIG=1 when calling make.

To build both static libbpf.a and shared libbpf.so:

$cd src$ make

To build only static libbpf.a library in directorybuild/ and install them together with libbpf headers in a staging directoryroot/:

$cd src$ 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 libelfdependency installed in /build/root/ and install them together with libbpfheaders in a build directory /build/root/:

$cd src$ PKG_CONFIG_PATH=/build/root/lib64/pkgconfig DESTDIR=/build/root make install

Libbpf supports building BPF CO-RE-enabled applications, which, in contrast toBCC, do not require Clang/LLVM runtimebeing deployed to target servers and doesn't rely on kernel-devel headersbeing available.

It does rely on kernel to be built withBTF typeinformation, 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 customkernel. You'll need:

• pahole 1.16+ tool (part ofdwarves package), which performs DWARF toBTF conversion;
• kernel built withCONFIG_DEBUG_INFO_BTF=y option;
• you can check if your kernel has BTF built-in by looking for/sys/kernel/btf/vmlinux file:

$ 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 followingdistributions 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 touse it:

• BPF CO-RE reference guide
• BPF Portability and CO-RE
• HOWTO: BCC to libbpf conversion
• libbpf-tools in BCC repocontain lots of real-world tools converted from BCC to BPF CO-RE. Considerconverting some more to both contribute to the BPF community and gain somemore experience with it.

Distributions packaging libbpf from this mirror:

• Fedora
• Gentoo
• Debian
• Arch
• Ubuntu
• Alpine

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 ofkernel versions. It has built-in mechanisms to gracefully handle olderkernels, that are missing some of the features, by working around orgracefully degrading functionality. Thus libbpf is not tied to a specifickernel version and can/should be packaged and versioned independently.
• Continuous integration testing viaGitHub Actions.
• Static code analysis viaLGTMandCoverity.

Package dependencies of libbpf, package names may vary across distros:

• zlib
• libelf

All the gory details of syncing can be found inscripts/sync-kernel.shscript. SeeSYNC.md for instruction.

Some header files in this repo (include/linux/*.h) are reduced versions oftheir counterpart files atbpf-next'stools/include/linux/*.h to make compilation successful.

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