On Tue, Jan 28, 2025 at 05:40:44PM -0800, Ian Rogers wrote: > 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. Cool :) > 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. I believe the "legacy" symbol format is still the rust default. So probably can't remove that. Looks like there's some desire to change that, probably probably not very soon [0]. That probably also explains why nobody reported the breakage - only very cool kids are using v0 scheme currently. Thanks, Daniel [0]: https://github.com/rust-lang/rust/pull/89917
