77 строки
2.3 KiB
ReStructuredText
77 строки
2.3 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.
|
|
|
|
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 version
|
|
and supported targets with command: ``llc --version``
|
|
|
|
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 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.
|
|
|
|
It is also possible to call make from this directory. This will just
|
|
hide the the invocation of make as above with the appended "/".
|
|
|
|
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"
|
|
|
|
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' 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
|
|
|
|
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.
|
|
|
|
export ARCH=arm64
|
|
export CROSS_COMPILE="aarch64-linux-gnu-"
|
|
make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
|