From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: [net-next PATCH V3 3/5] samples/bpf: add a README file to get users started Date: Wed, 27 Apr 2016 09:30:23 +0200 Message-ID: <20160427073023.29959.17816.stgit@firesoul> References: <20160427072855.29959.70252.stgit@firesoul> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: linux-kbuild@vger.kernel.org, bblanco@plumgrid.com, Jesper Dangaard Brouer , naveen.n.rao@linux.vnet.ibm.com, borkmann@iogearbox.net, alexei.starovoitov@gmail.com To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:43486 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753297AbcD0HaZ (ORCPT ); Wed, 27 Apr 2016 03:30:25 -0400 In-Reply-To: <20160427072855.29959.70252.stgit@firesoul> Sender: netdev-owner@vger.kernel.org List-ID: Getting started with using examples in samples/bpf/ is not straightforward. There are several dependencies, and specific versions of these dependencies. Just compiling the example tool is also slightly obscure, e.g. one need to call make like: make samples/bpf/ Do notice the "/" slash after the directory name. Signed-off-by: Jesper Dangaard Brouer --- samples/bpf/README.rst | 75 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 samples/bpf/README.rst diff --git a/samples/bpf/README.rst b/samples/bpf/README.rst new file mode 100644 index 000000000000..1fa157db905b --- /dev/null +++ b/samples/bpf/README.rst @@ -0,0 +1,75 @@ +eBPF sample programs +==================== + +This kernel samples/bpf directory contains a mini eBPF library, test +stubs, verifier test-suite and examples for using eBPF. + +Build dependencies +================== + +Compiling requires having installed: + * clang >= version 3.4.0 + * llvm >= version 3.7.1 + +Note that LLVM's tool 'llc' must support target 'bpf', list with command:: + + $ llc --version + LLVM (http://llvm.org/): + LLVM version 3.x.y + [...] + Host CPU: xxx + + Registered Targets: + [...] + bpf - BPF (host endian) + bpfeb - BPF (big endian) + bpfel - BPF (little endian) + [...] + +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 creates a local "usr/include" directory in the git/build top +level directory, that the make system automatically pickup first. + +Compiling +========= + +For compiling goto kernel top level build directory and run make like:: + + make samples/bpf/ + +Do notice the "/" slash after the directory name. + +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;X86" + +Quick sniplet for manually compiling LLVM and clang +(build dependencies are 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) + +It is also possible to point make to the newly compiled 'llc' command +via redefining LLC on the make command line:: + + make samples/bpf/ LLC=~/git/llvm/build/bin/llc +