122 lines
3.9 KiB
ReStructuredText
122 lines
3.9 KiB
ReStructuredText
eBPF sample programs
|
|
====================
|
|
|
|
This directory contains a test stubs, verifier test-suite and examples
|
|
for using eBPF. The examples use libbpf from tools/lib/bpf.
|
|
|
|
Note that the XDP-specific samples have been removed from this directory and
|
|
moved to the xdp-tools repository: https://github.com/xdp-project/xdp-tools
|
|
See the commit messages removing each tool from this directory for how to
|
|
convert specific command invocations between the old samples and the utilities
|
|
in xdp-tools.
|
|
|
|
Build dependencies
|
|
==================
|
|
|
|
Compiling requires having installed:
|
|
* clang
|
|
* llvm
|
|
* pahole
|
|
|
|
Consult :ref:`Documentation/process/changes.rst <changes>` for the minimum
|
|
version numbers required and how to update them. Note that LLVM's tool
|
|
'llc' must support target 'bpf', list version and supported targets with
|
|
command: ``llc --version``
|
|
|
|
Clean and configuration
|
|
-----------------------
|
|
|
|
It can be needed to clean tools, samples or kernel before trying new arch or
|
|
after some changes (on demand)::
|
|
|
|
make -C tools clean
|
|
make -C samples/bpf clean
|
|
make clean
|
|
|
|
Configure kernel, defconfig for instance
|
|
(see "tools/testing/selftests/bpf/config" for a reference config)::
|
|
|
|
make defconfig
|
|
|
|
Kernel headers
|
|
--------------
|
|
|
|
There are usually dependencies to header files of the current kernel.
|
|
To avoid installing devel kernel headers system wide, as a normal
|
|
user, simply call::
|
|
|
|
make headers_install
|
|
|
|
This will create a local "usr/include" directory in the git/build top
|
|
level directory, that the make system will automatically pick up first.
|
|
|
|
Compiling
|
|
=========
|
|
|
|
For building the BPF samples, issue the below command from the kernel
|
|
top level directory::
|
|
|
|
make M=samples/bpf
|
|
|
|
It is also possible to call make from this directory. This will just
|
|
hide the invocation of make as above.
|
|
|
|
Manually compiling LLVM with 'bpf' support
|
|
------------------------------------------
|
|
|
|
Since version 3.7.0, LLVM adds a proper LLVM backend target for the
|
|
BPF bytecode architecture.
|
|
|
|
By default llvm will build all non-experimental backends including bpf.
|
|
To generate a smaller llc binary one can use::
|
|
|
|
-DLLVM_TARGETS_TO_BUILD="BPF"
|
|
|
|
We recommend that developers who want the fastest incremental builds
|
|
use the Ninja build system, you can find it in your system's package
|
|
manager, usually the package is ninja or ninja-build.
|
|
|
|
Quick sniplet for manually compiling LLVM and clang
|
|
(build dependencies are ninja, cmake and gcc-c++)::
|
|
|
|
$ git clone https://github.com/llvm/llvm-project.git
|
|
$ mkdir -p llvm-project/llvm/build
|
|
$ cd llvm-project/llvm/build
|
|
$ cmake .. -G "Ninja" -DLLVM_TARGETS_TO_BUILD="BPF;X86" \
|
|
-DLLVM_ENABLE_PROJECTS="clang" \
|
|
-DCMAKE_BUILD_TYPE=Release \
|
|
-DLLVM_BUILD_RUNTIME=OFF
|
|
$ ninja
|
|
|
|
It is also possible to point make to the newly compiled 'llc' or
|
|
'clang' command via redefining LLC or CLANG on the make command line::
|
|
|
|
make M=samples/bpf LLC=~/git/llvm-project/llvm/build/bin/llc CLANG=~/git/llvm-project/llvm/build/bin/clang
|
|
|
|
Cross compiling samples
|
|
-----------------------
|
|
In order to cross-compile, say for arm64 targets, export CROSS_COMPILE and ARCH
|
|
environment variables before calling make. But do this before clean,
|
|
configuration and header install steps described above. This will direct make to
|
|
build samples for the cross target::
|
|
|
|
export ARCH=arm64
|
|
export CROSS_COMPILE="aarch64-linux-gnu-"
|
|
|
|
Headers can be also installed on RFS of target board if need to keep them in
|
|
sync (not necessarily and it creates a local "usr/include" directory also)::
|
|
|
|
make INSTALL_HDR_PATH=~/some_sysroot/usr headers_install
|
|
|
|
Pointing LLC and CLANG is not necessarily if it's installed on HOST and have
|
|
in its targets appropriate arm64 arch (usually it has several arches).
|
|
Build samples::
|
|
|
|
make M=samples/bpf
|
|
|
|
Or build samples with SYSROOT if some header or library is absent in toolchain,
|
|
say libelf, providing address to file system containing headers and libs,
|
|
can be RFS of target board::
|
|
|
|
make M=samples/bpf SYSROOT=~/some_sysroot
|