Thanks for the info Xiang! I was on the right track but it is good to have some affirmation that I'm not missing something.
The issue with the Arm maintained toolchain, as Greg has warned many times, is its use of newlib. Are you doing anything to ensure the wrong math library is not used? I will work on improving buildroot to also build and include libsupcxx.a. With Alan's modified version of libcxx, he disabled some exception logic and maybe some other logic that was allowing me to build without libsupxx.a entirely. Also, may I ask why we are building libcxx by manually grabbing the source files and building it? Are we against just driving the build from their existing build system? I ask because there are options in the way libcxx is built that might be useful to us and we have to replicate all of that if we just grab the source. Best, Anthony On Sat, Jan 9, 2021, 7:32 AM Xiang Xiao <xiaoxiang781...@gmail.com> wrote: > On Fri, Jan 8, 2021 at 9:57 AM Anthony Merlino <anth...@vergeaero.com> > wrote: > > > Hey all, > > > > Would someone be willing to share their experience with libcxx and their > > toolchain? > > > This toolchain should work: > > https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm > > > > I've now caught up to the tip of master, which now downloads > > and builds libcxx for me instead of using Alan's modified version. I am > > facing an issue I've faced before, and would really love to properly > > understand how this is supposed to work. > > > > My issues mostly center around libsupc++.a > > > > Currently, my build fails because it can't find libsupc++. From my > > understanding, this should be provided by my toolchain. But I am using a > > toolchain built by the NuttX buildroot and it does not build the C++ > > libraries. I am not using RTTI or exceptions, so I don't need what > > > > libsupc++.a doesn't only provide RTTI and exectpions, but also provide some > basic functions called by compiler: > > https://github.com/gcc-mirror/gcc/tree/master/libstdc%2B%2B-v3/libsupc%2B%2B > > libsupc++ provides, however the Kconfig option > > `[ ] Have libsupc++ (required)` > > says, it's required. > > > > What's the right answer here? What are others doing about this? > > > > > Three methods you can try: > > 1. Switch to the ARM maintained toolchain > 2. Build libsupc++.a for NuttX toolchain > 3. Enhance NuttX's libc++ runtime support > > > https://github.com/apache/incubator-nuttx/tree/master/libs/libxx > > > > Is getting NuttX buildroot to build and provide libsupc++.a the *right* > > solution? > > > > > Yes, a complete toolchain should provide libsupc++.a. libsupc++.a just like > libgcc.a should part of toolchain, not part of c/c++ library > implemetnation, because libsupc++.a tightly couple with the implementaion > detail of compiler. > > > > Do we need to change how libcxx is built in this case? > > > > > https://libcxx.llvm.org/docs/BuildingLibcxx.html#using-alternate-abi-libraries > > > > > Then you need port the libcxxrt: > https://github.com/libcxxrt/libcxxrt > > > > Thank you! > > > > Anthony > > >
