On Wed, Feb 19, 2020 at 1:59 PM Daniel Díaz <daniel.diaz@xxxxxxxxxx> wrote: > > Hello! > > On Wed, 19 Feb 2020 at 14:06, Jesper Dangaard Brouer <brouer@xxxxxxxxxx> wrote: > > > > On Wed, 19 Feb 2020 10:38:45 -0800 > > Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > > > > On Wed, Feb 19, 2020 at 10:29 AM Jesper Dangaard Brouer > > > <brouer@xxxxxxxxxx> wrote: > > > > > > > > On Wed, 19 Feb 2020 09:38:50 -0800 > > > > Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > > > > > > > > On Wed, Feb 19, 2020 at 9:04 AM Jesper Dangaard Brouer > > > > > <brouer@xxxxxxxxxx> wrote: > > > > > > > > > > > > On Wed, 19 Feb 2020 08:41:27 -0800 > > > > > > Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote: > > > > > > > > > > > > > On Wed, Feb 19, 2020 at 4:30 AM Jesper Dangaard Brouer > > > > > > > <brouer@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > I'm willing to help out, such that we can do either version or feature > > > > > > > > detection, to either skip compiling specific test programs or at least > > > > > > > > give users a proper warning of they are using a too "old" LLVM version. > > > > > > > ... > > > > > > > > progs/test_core_reloc_bitfields_probed.c:47:13: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration] > > > > > > > > out->ub1 = BPF_CORE_READ_BITFIELD_PROBED(in, ub1); > > > > > > > > > > > > > > imo this is proper warning message already. > > > > > > > > > > > > This is an error, not a warning. The build breaks as the make process stops. > > > > > > > > > > > > > > > > Latest Clang was a requirement for building and running all selftests > > > > > for a long time now. There were few previous discussions on mailing > > > > > list about this and each time the conclusion was the same: latest > > > > > Clang is a requirement for BPF selftests. > > > > > > > > The latest Clang is 9.0.1, and it doesn't build with that. > > > > > > Latest as in "latest built from sources". > > > > When I download a specific kernel release, how can I know what LLVM > > git-hash or version I need (to use BPF-selftests)? > > > > Do you think it is reasonable to require end-users to compile their own > > bleeding edge version of LLVM, to use BPF-selftests? > > > > I do hope that some end-users of BPF-selftests will be CI-systems. > > That also implies that CI-system maintainers need to constantly do > > "latest built from sources" of LLVM git-tree to keep up. Is that a > > reasonable requirement when buying a CI-system in the cloud? > > We [1] are end users of kselftests and many other test suites [2]. We > run all of our testing on every git-push on linux-stable-rc, mainline, > and linux-next -- approximately 1 million tests per week. We have a > dedicated engineering team looking after this CI infrastructure and > test results, and as such, I can wholeheartedly echo Jesper's > sentiment here: We would really like to help kernel maintainers and > developers by automatically testing their code in real hardware, but > the BPF kselftests are difficult to work with from a CI perspective. > We have caught and reported [3] many [4] build [5] failures [6] in the > past for libbpf/Perf, but building is just one of the pieces. We are > unable to run the entire BPF kselftests because only a part of the > code builds, so our testing is very limited there. > > We hope that this situation can be improved and that our and everyone > else's automated testing can help you guys too. For this to work out, > we need some help. Is it hard to make sure that your CIs install latest builds of Clang, though? See [0], Clang has even latest Clang 11 snapshots available (though BPF selftests need only Clang 10 right now). In fact, libbpf's Github repo just got a support for building latest kernel + building latest selftests + running selftests in QEMU, performed for each PR ([1]), in Travis CI. Making selftests silently being not built/run if Clang is too old will just hide problems without anyone noticing. [0] http://apt.llvm.org/ [1] https://travis-ci.org/libbpf/libbpf/jobs/651838387?utm_medium=notification&utm_source=github_status > > [1] https://lkft.linaro.org/ > [2] https://www.youtube.com/watch?v=R3H9fPhPf54&t=1m26s > [3] https://lore.kernel.org/bpf/CA+G9fYtAQGwf=OoEvHwbJpitcfhpfhy-ar+6FRrWC_-ti7sUTg@xxxxxxxxxxxxxx/ > [4] https://lore.kernel.org/stable/CA+G9fYtxRoK6D1_oMf9zQj8MW0JtPdphDDO1NHcYQcoFNL5pjw@xxxxxxxxxxxxxx/ > [5] https://lore.kernel.org/bpf/CA+G9fYssgDcBkiNGSV7BmjE4Tj1j1_fa4VTJFv3N=2FHzewQLg@xxxxxxxxxxxxxx/ > [6] https://lore.kernel.org/bpf/CA+G9fYsK8zn3jqF=Wz6=8BBx4i1JTkv2h-LCbjE11UJkcz_NEA@xxxxxxxxxxxxxx/
