Building RISC-V Target with Cmake

Warning Runtime rvv detection (using hwcap) requires linux kernel 6.5 or newer.

When running on older kernels, we fall back to compile-time detection, potentially this can cause crashes if rvv is enabled at compile but not supported by the target cpu. Therefore if older kernel support is needed, rvv should be disabled if the target cpu does not support it.

Prerequisite: Build RISC-V Clang Toolchain and QEMU

If you don't have prebuilt clang and riscv64 qemu, you can refer to the script to get the source. Copy the script to the zlib-ng root directory, and run it to download the source and build them. Modify the content according to your conditions (e.g., toolchain version).

./prepare_riscv_toolchain_qemu.sh

After running script, clang & qemu are built in build-toolchain-qemu/riscv-clang/ & build-toolchain-qemu/riscv-qemu/.

build-toolchain-qemu/riscv-clang/ is your TOOLCHAIN_PATH. build-toolchain-qemu/riscv-qemu/bin/qemu-riscv64 is your QEMU_PATH.

You can also download the prebuilt toolchain & qemu from the release page, and enjoy using them.

Cross-Compile for RISC-V Target

cmake -G Ninja -B ./build-riscv \
  -D CMAKE_TOOLCHAIN_FILE=./cmake/toolchain-riscv.cmake \
  -D CMAKE_INSTALL_PREFIX=./build-riscv/install \
  -D TOOLCHAIN_PATH={TOOLCHAIN_PATH} \
  -D QEMU_PATH={QEMU_PATH} \
  .

cmake --build ./build-riscv

Disable the option if there is no RVV support:

-D WITH_RVV=OFF

Run Unittests on User Mode QEMU

cd ./build-riscv && ctest --verbose