On Tue, Jan 28, 2025 at 4:31 PM Daniel Xu <dxu@xxxxxxxxx> wrote: > > Hi Ian, > > On Wed, Jan 22, 2025 at 09:43:03AM -0800, Ian Rogers wrote: > > libbfd is license incompatible with perf and building requires the > > BUILD_NONDISTRO=1 build flag. Remove the code to simplify the code > > base. > > > > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx> > > --- > > tools/perf/Documentation/perf-check.txt | 1 - > > tools/perf/Makefile.config | 38 +--- > > tools/perf/builtin-check.c | 1 - > > tools/perf/tests/Build | 1 - > > tools/perf/tests/builtin-test.c | 1 - > > tools/perf/tests/pe-file-parsing.c | 101 ---------- > > tools/perf/tests/tests.h | 1 - > > tools/perf/util/demangle-cxx.cpp | 13 +- > > tools/perf/util/disasm_bpf.c | 166 ---------------- > > tools/perf/util/srcline.c | 243 +----------------------- > > tools/perf/util/symbol-elf.c | 86 +-------- > > tools/perf/util/symbol.c | 135 ------------- > > tools/perf/util/symbol.h | 4 - > > 13 files changed, 7 insertions(+), 784 deletions(-) > > delete mode 100644 tools/perf/tests/pe-file-parsing.c > > [..] > > I was briefly investigating why the centos build of perf was not > demangling rust v0 symbols [0]. From looking at the rust issue [1], it > appears the rust team somehow delivered support for v0 demangling > through libbfd. The code itself looked a bit odd (relying on cxx > demangle to run first?), but that's a separate thing. There is still C++ demangling support by way of cxxabi: https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/util/demangle-cxx.cpp?h=perf-tools-next#n44 that was in libstdc++ (GNU) and libcxx (LLVM) when I looked. > The centos build does not build with libbfd for the license issues you > mentioned. So your change probably won't regress any distro use cases. > But it does remove support for motivated users who don't have > re-distribution requirements. > > But since this patchset came up first in my search, I thought it'd be > good to mention that someone probably needs to add v0 support to > tools/perf/util/demangle-rust.c. So I don't see any libbfd dependencies in demangle-rust.c: https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/util/demangle-rust.c?h=perf-tools-next#n8 Unusually we don't have any tests on the Rust demangling, we do for Java and OCaml: https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/tests/demangle-java-test.c?h=perf-tools-next https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/tests/demangle-ocaml-test.c?h=perf-tools-next Reading a bit more it seems that previous libiberty was coming to the rescue by way of C++ demangling. I'll see if I can write a demangler by way of lex and yacc. If we have a v0 standard one is there any value in the existing demangler or legacy demangling? It seems this has been broken for the best part of 5 years. Thanks, Ian > Thanks, > Daniel > > > [0]: https://doc.rust-lang.org/rustc/symbol-mangling/v0.html > [1]: https://github.com/rust-lang/rust/issues/60705
