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Diffstat (limited to 'samples/bpf/README.rst')
| -rw-r--r-- | samples/bpf/README.rst | 91 |
1 files changed, 68 insertions, 23 deletions
diff --git a/samples/bpf/README.rst b/samples/bpf/README.rst index 5f27e4faca50..cabe2d216997 100644 --- a/samples/bpf/README.rst +++ b/samples/bpf/README.rst @@ -4,15 +4,39 @@ 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 >= version 3.4.0 - * llvm >= version 3.7.1 + * 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 +----------------------- -Note that LLVM's tool 'llc' must support target 'bpf', list version -and supported targets with command: ``llc --version`` +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 -------------- @@ -23,8 +47,8 @@ user, simply call:: make headers_install -This will creates a local "usr/include" directory in the git/build top -level directory, that the make system automatically pickup first. +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 ========= @@ -32,12 +56,10 @@ Compiling For building the BPF samples, issue the below command from the kernel top level directory:: - make samples/bpf/ - -Do notice the "/" slash after the directory name. + make M=samples/bpf It is also possible to call make from this directory. This will just -hide the the invocation of make as above with the appended "/". +hide the invocation of make as above. Manually compiling LLVM with 'bpf' support ------------------------------------------ @@ -50,27 +72,50 @@ 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 cmake and gcc-c++):: +(build dependencies are ninja, cmake and gcc-c++):: - $ git clone http://llvm.org/git/llvm.git - $ cd llvm/tools - $ git clone --depth 1 http://llvm.org/git/clang.git - $ cd ..; mkdir build; cd build - $ cmake .. -DLLVM_TARGETS_TO_BUILD="BPF;X86" - $ make -j $(getconf _NPROCESSORS_ONLN) + $ 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 samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang + 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. This will direct make to build -samples for the cross target. +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:: -export ARCH=arm64 -export CROSS_COMPILE="aarch64-linux-gnu-" -make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang + make M=samples/bpf SYSROOT=~/some_sysroot |