# this script will download Python source code, compile it, and install it to /usr/local/lib
# then use this python to compile cross-compiled python for aarch64

wget https://www.python.org/ftp/python/3.10.10/Python-3.10.10.tgz
tar -xvf Python-3.10.10.tgz
cd Python-3.10.10
# explain Python compile options here a bit:s
# --enable-shared: enable building a shared Python library (default is no) but we do need it for calling from rust
# CC, CXX, AR, LD, RANLIB: set the compiler, archiver, linker, and ranlib programs to use
# build: the machine you are building on, host: the machine you will run the compiled program on
# --with-system-ffi: build _ctypes module using an installed ffi library, see Doc/library/ctypes.rst, not used in here TODO: could remove
# ac_cv_pthread_is_default=no ac_cv_pthread=yes ac_cv_cxx_thread=yes:
# allow cross-compiled python to have -pthread set for CXX, see https://github.com/python/cpython/pull/22525
# ac_cv_have_long_long_format=yes: target platform supports long long type
# disable-ipv6: disable ipv6 support, we don't need it in here
# ac_cv_file__dev_ptmx=no ac_cv_file__dev_ptc=no: disable pty support, we don't need it in here

# Build local python first, then build cross-compiled python.
./configure \
--enable-shared \
ac_cv_pthread_is_default=no ac_cv_pthread=yes ac_cv_cxx_thread=yes \
ac_cv_have_long_long_format=yes \
--disable-ipv6 ac_cv_file__dev_ptmx=no ac_cv_file__dev_ptc=no && \
make
make install
cd ..
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib/
export LIBRARY_PATH=$LIBRARY_PATH:/usr/local/lib/
export PY_INSTALL_PATH=$(pwd)/python_arm64_build
cd Python-3.10.10 && \
make clean && \
make distclean && \
alias python=python3 && \
./configure --build=x86_64-linux-gnu --host=aarch64-linux-gnu \
--prefix=$PY_INSTALL_PATH --enable-optimizations \
CC=aarch64-linux-gnu-gcc \
CXX=aarch64-linux-gnu-g++ \
AR=aarch64-linux-gnu-ar \
LD=aarch64-linux-gnu-ld \
RANLIB=aarch64-linux-gnu-ranlib \
--enable-shared \
ac_cv_pthread_is_default=no ac_cv_pthread=yes ac_cv_cxx_thread=yes \
ac_cv_have_long_long_format=yes \
--disable-ipv6 ac_cv_file__dev_ptmx=no ac_cv_file__dev_ptc=no && \
make && make altinstall && \
cd ..