Add list of Linux distributions with kernel BTF built-in. Give few useful links to BPF CO-RE-related material to help users get started.
5.5 KiB
This is a mirror of bpf-next linux tree's
tools/lib/bpf
directory plus its supporting header files.
The following files will by sync'ed with bpf-next repo:
src/
<->bpf-next/tools/lib/bpf/
include/uapi/linux/bpf_common.h
<->bpf-next/tools/include/uapi/linux/bpf_common.h
include/uapi/linux/bpf.h
<->bpf-next/tools/include/uapi/linux/bpf.h
include/uapi/linux/btf.h
<->bpf-next/tools/include/uapi/linux/btf.h
include/uapi/linux/if_link.h
<->bpf-next/tools/include/uapi/linux/if_link.h
include/uapi/linux/if_xdp.h
<->bpf-next/tools/include/uapi/linux/if_xdp.h
include/uapi/linux/netlink.h
<->bpf-next/tools/include/uapi/linux/netlink.h
include/tools/libc_compat.h
<->bpf-next/tools/include/tools/libc_compat.h
Other header files at this repo (include/linux/*.h
) are reduced versions of
their counterpart files at bpf-next's tools/include/linux/*.h
to make compilation
successful.
Build
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:
$ 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/:
$ 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/:
$ cd src
$ PKG_CONFIG_PATH=/build/root/lib64/pkgconfig DESTDIR=/build/root make install
Distributions
Distributions packaging libbpf from this mirror:
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 TravisCI.
- Static code analysis via LGTM and Coverity.
Package dependencies of libbpf, package names may vary across distros:
- zlib
- libelf
BPF CO-RE (Compile Once – Run Everywhere)
Libbpf supports building BPF CO-RE-enabled applications, which, in contrast to 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, though. Some major Linux distributions come with kernel BTF already built in:
- Fedora 31+
- RHEL 8.2+
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 ofdwarves
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:
$ 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+ installed by default:
- Fedora 32+
- Ubuntu 20.04+
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 Portability and CO-RE
- HOWTO: BCC to libbpf conversion
- libbpf-tools in BCC repo 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.
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