On Tue, Jun 03, 2025 at 07:42:55AM -0700, Raymond Mao wrote: > MbedTLS bignum module needs '__udivti3' which is a 128-bit division > function provided by the compiler runtime, typically libgcc for GCC or > clang_rt.builtins for Clang. > Thus 'clang_rt.builtins' library is required when building using Clang. > > This patch supports the location layout of clang_rt.builtins libraries > from both LLVM pre-15 pattern [1] and post-15(up to 20) pattern [2]. > > As a fact that starts from LLVM 20, no official prebuilt multi-targets > are included and users might need to cross-built it from source. [3] is > an example of instructions for building. > > [1] <INST_DIR>/lib/clang/<REV>/lib/linux/libclang_rt.builtins-<ARCH>.a > E.g. > lib/clang/14.0.0/lib/linux/libclang_rt.builtins-aarch64.a > lib/clang/14.0.0/lib/linux/libclang_rt.builtins-x86_64.a > > [2] <INST_DIR>/lib/clang/<REV_MAJOR>/lib/<CROSSTOOL>/libclang_rt.builtins.a > E.g. > lib/clang/20/lib/aarch64-none-linux-gnu/libclang_rt.builtins.a > lib/clang/20/lib/x86_64-unknown-linux-gnu/libclang_rt.builtins.a > > [3] > git clone https://github.com/llvm/llvm-project.git > cd llvm-project > git checkout -b llvmorg-20.1.6 llvmorg-20.1.6 > mkdir build-builtin && cd build-builtin > cmake -G Ninja ../llvm \ > -DCMAKE_BUILD_TYPE=Release \ > -DCMAKE_C_COMPILER=clang \ > -DLLVM_ENABLE_PROJECTS="clang" \ > -DLLVM_ENABLE_RUNTIMES="compiler-rt" \ > -DLLVM_TARGETS_TO_BUILD="X86;AArch64" \ > -DLLVM_BUILTIN_TARGETS=\ > "x86_64-unknown-linux-gnu;aarch64-none-linux-gnu" \ > -DBUILTINS_aarch64-none-linux-gnu_CMAKE_SYSTEM_NAME=Linux \ > -DBUILTINS_aarch64-none-linux-gnu_CMAKE_C_COMPILER=\ > <YOUR_TOOLCHAIN_GCC> \ > -DBUILTINS_aarch64-none-linux-gnu_CMAKE_ASM_COMPILER=\ > <YOUR_TOOLCHAIN_GCC> \ > -DBUILTINS_aarch64-none-linux-gnu_CMAKE_SYSROOT=\ > <YOUR_TOOLCHAIN_LIBC_DIR> \ > -DCOMPILER_RT_BUILD_BUILTINS=ON \ > -DCOMPILER_RT_BUILD_SANITIZERS=OFF \ > -DCOMPILER_RT_BUILD_XRAY=OFF \ > -DCOMPILER_RT_BUILD_LIBFUZZER=OFF \ > -DCOMPILER_RT_BUILD_PROFILE=OFF \ > -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR> \ > -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF > ninja builtins > sudo ninja install > > Fixes: 13de8483388c ("mbedtls: add mbedtls into the build system") > Signed-off-by: Raymond Mao <raymond....@linaro.org>
I think that newer versions don't even ship this moves us further away from a solution here as all of the logic. I think we need to look at the suggestion of just importing the assembly version of the function. -- Tom
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