On Wed, 27 Apr 2016 14:05:22 +0530 "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxxxxxxx> wrote: > On 2016/04/27 09:30AM, Jesper Dangaard Brouer wrote: > > 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 <brouer@xxxxxxxxxx> > > --- > > samples/bpf/README.rst | 75 ++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 75 insertions(+) > > create mode 100644 samples/bpf/README.rst > > Thanks for adding this! A few nits... I would prefer if we could apply this patchset and you could followup with a patch with your nits... > > > > 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 > ^^^^^^^^^^^^^^^^^^ > 'This directory contains' should suffice. The reason I formulated it like this, was that people will often hit this kind of documentation when searching google. > > +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 > > 'llc --version | grep bpf' is probably simpler? I wanted to give people the impression of how the output looks like. > > + 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:: > > For building the BPF samples, issue the below command from the kernel > root directory: I like your formulation better, but it it worth a respin of the entire patchset? Notice you need the extra "::" ending of the paragraph, to make this document format nicely with RST (ReStructuredText). The a README with a .rst suffix will be picked up by github and displayed as the doc for the directory. Thus I also made sure it "compiles" with the rst tools. E.g see how samples/pktgen gets auto documented and nicely formatted via github (scroll down): https://github.com/torvalds/linux/tree/master/samples/pktgen > > + > > + 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" > > Is the X86 target really needed? I'm not sure, but if you want to use clang/llc for something else it is useful, and the example usage of the ";" separator syntax makes it worth including as an example. > > + > > +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" > ^^^ > Here too. > > - Naveen > > > + $ 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 > > + > > > -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
