R-Pi Developement

Cross Compilation

use docker image.

compilers

use the compilers in the docker image:

aarch64-linux-gnu-g++-9
aarch64-linux-gnu-gcc-9

cmake

if not using multiarch, CMAKE_SYSROOT variable needs to be set to where there's an exact copy of the root filesystem of the target device. cmake find_* commands will look in the sysroot, and the CMAKE_FIND_ROOT_PATH entries by default in all cases, as well as looking in the host system root prefix. software/opencv-test/toolchain-aarch64.cmake should cover both.

opencv

cmake -DCMAKE_BUILD_TYPE=RELEASE \
	-DCMAKE_TOOLCHAIN_FILE=../platforms/linux/aarch64-gnu.toolchain.cmake \
	-DBUILD_TESTS=OFF \
	-DBUILD_DOCS=OFF \
	-DPYTHON3_INCLUDE_PATH=/usr/include/python3.8 \
	-DPYTHON3_LIBRARIES=/usr/lib/aarch64-linux-gnu/libpython3.8.so \
	-DPYTHON3_NUMPY_INCLUDE_DIRS=/usr/lib/python3/dist-packages/numpy/core/include \
	-DBUILD_OPENCV_PYTHON3=ON \
	-DBUILD_OPENCV_PYTHON2=OFF \
	-DENABLE_NEON=ON \
	-DBUILD_EXAMPLES=OFF ..

cannot enable VFPV3:

Required baseline optimization is not supported: VFPV3
(CPU_BASELINE_REQUIRE=;VFPV3;NEON)