On Tue, Apr 26, 2016 at 02:40:54PM +0200, Daniel Borkmann wrote: > On 04/26/2016 01:56 PM, Jesper Dangaard Brouer wrote: > >>>+Compiling requires having installed: > >>>+ * clang > >>>+ * llvm >= version 3.7.0 please change it to 3.7.1, since 3.7.0 had several bugs. They're rare, but better to avoid the issue. > >>>+ > >>>+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) there always be 3 targets for bpf, since some folks need to cross-compile. > >>>+Manually compiling LLVM with 'bpf' support > >>>+------------------------------------------ > >>>+ > >>>+In some LLVM versions the BPF target were marked experimental. To > >>>+compile LLVM manually and enable BPF target run (build dependencies > >>>+are cmake and gcc-c++):: > >>>+ > >>>+ $ git clone http://llvm.org/git/llvm.git > >>>+ $ cd llvm > >>>+ $ mkdir build; cd build > >>>+ $ cmake .. -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=BPF > >>>+ $ make > >> > >>That's perhaps a bit misleading in the sense that when you clone the > >>tree from git, you'd nowadays invoke cmake normally with LLVM_TARGETS_TO_BUILD > >>instead of LLVM_EXPERIMENTAL_TARGETS_TO_BUILD for BPF, as BPF is not an > >>experimental target anymore. It's probably also recommended to clone > >>clang into tools/ dir as well under your llvm/ repo when you compile > >>from scratch anyways. yes. LLVM_EXPERIMENTAL_TARGETS_TO_BUILD is the thing of the past when bpf was just merged into llvm < 3.7 By default llvm will build all non-experimental backends including bpf. If you need to make llc binary smaller you can use: -DLLVM_TARGETS_TO_BUILD="BPF;X86" Also fedora and ubuntu ship with llvm that has bpf support. > >Can you come up with a formulation/desc I can use instead then? > > You mean how to build with clang? There are various docs/snippets out > there, for example, see the 'Build LLVM and Clang development libs' > part of [1], that you can tweak for your README with. > > [1] https://gist.github.com/brendangregg/cfa482acb71aa577789c yep. +1 for the link. -- 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
