On Tue, 19 May 2020, Alexei Starovoitov wrote: > On Mon, May 18, 2020 at 12:23:10PM +0100, Alan Maguire wrote: > > Getting a clean BPF selftests run involves ensuring latest trunk LLVM/clang > > are used, pahole is recent (>=1.16) and config matches the specified > > config file as closely as possible. Document all of this in the general > > README.rst file. Also note how to work around timeout failures. > > > > Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx> > > --- > > tools/testing/selftests/bpf/README.rst | 46 ++++++++++++++++++++++++++++++++++ > > 1 file changed, 46 insertions(+) > > > > diff --git a/tools/testing/selftests/bpf/README.rst b/tools/testing/selftests/bpf/README.rst > > index 0f67f1b..b00eebb 100644 > > --- a/tools/testing/selftests/bpf/README.rst > > +++ b/tools/testing/selftests/bpf/README.rst > > @@ -1,6 +1,52 @@ > > ================== > > BPF Selftest Notes > > ================== > > +First verify the built kernel config options match the config options > > +specified in the config file in this directory. Test failures for > > +unknown helpers, inability to find BTF etc will be observed otherwise. > > + > > +To ensure the maximum number of tests pass, it is best to use the latest > > +trunk LLVM/clang, i.e. > > + > > +git clone https://github.com/llvm/llvm-project > > + > > +Build/install trunk LLVM: > > + > > +.. code-block:: bash > > + git clone https://github.com/llvm/llvm-project > > + cd llvm-project > > + mkdir build/llvm > > + cd build/llvm > > + cmake ../../llvm/ > > + make > > + sudo make install > > + cd ../../ > > + > > +Build/install trunk clang: > > + > > +.. code-block:: bash > > + mkdir -p build/clang > > + cd build/clang > > + cmake ../../clang > > + make > > + sudo make install > > + > > these instructions are obsolete and partially incorrect. > May be refer to Documentation/bpf/bpf_devel_QA.rst instead? > Sure; looks like there are up-to-date sections there on running BPF selftests and building LLVM manually. Perhaps I should add the notes about pahole etc there too? I should also have noted that without an up-to-date iproute2 failures will be observed also. > > +When building the kernel with CONFIG_DEBUG_INFO_BTF, pahole > > +version 16 or later is also required for BTF function > > +support. pahole can be built from the source at > > + > > +https://github.com/acmel/dwarves > > + > > +It is often available in "dwarves/libdwarves" packages also, > > +but be aware that versions prior to 1.16 will fail with > > +errors that functions cannot be found in BTF. > > + > > +When running selftests, the default timeout of 45 seconds > > +can be exceeded by some tests. We can override the default > > +timeout via a "settings" file; for example: > > + > > +.. code-block:: bash > > + echo "timeout=120" > tools/testing/selftests/bpf/settings > > Is it really the case? > I've never seen anything like this. > When running via "make run_tests" on baremetal systems I see test timeouts pretty consistently; e.g. from a bpf tree test run yesterday: not ok 6 selftests: bpf: test_progs # TIMEOUT not ok 31 selftests: bpf: test_tunnel.sh # TIMEOUT not ok 38 selftests: bpf: test_lwt_ip_encap.sh # TIMEOUT not ok 40 selftests: bpf: test_tc_tunnel.sh # TIMEOUT not ok 42 selftests: bpf: test_xdping.sh # TIMEOUT not ok 43 selftests: bpf: test_bpftool_build.sh # TIMEOUT These will only occur if running via "make run_tests", so running tests individually would not trigger these failures. Alan
