Cross compilation for performance

use Ubuntu 22.04 in WSL 2.

Build a working chroot using https://github.com/JeodC/PortMaster-ShipOfHarkinian/blob/main/BUILDING.md

In wsl2 Ubuntu :

sudo apt -y install wget gcc g++ git cmake ninja-build lsb-release libsdl2-dev libpng-dev libsdl2-net-dev libzip-dev zipcmp zipmerge ziptool nlohmann-json3-dev libtinyxml2-dev libspdlog-dev libboost-dev libopengl-dev libglew-dev gcc-12-aarch64-linux-gnu g++-12-aarch64-linux-gnu

All of those are necessary on the host machine to create the 2s2h.o2r file

mkdir ~/crosscompile
cd crosscompile

copy your sysroot into a new directory using

sudo cp -a /mnt/data/arm64 sysroot

Correct symlinks

wget https://raw.githubusercontent.com/riscv/riscv-poky/master/scripts/sysroot-relativelinks.py
chmod +x sysroot-relativelinks.py 
sudo python3 sysroot-relativelinks.py sysroot

create a crosscompilation CMake File

nano crosscompile.cmake

with the following content

# the name of the target operating system
set(CMAKE_SYSTEM_NAME Linux)
# set(CMAKE_SYSTEM_PROCESSOR aarch64)
# which compilers to use for C and C++
set(CMAKE_C_COMPILER   aarch64-linux-gnu-gcc-12)
set(CMAKE_CXX_COMPILER aarch64-linux-gnu-g++-12)
# set(CMAKE_LIBRARY_ARCHITECTURE aarch64-linux-gnu)


# where is the target environment located
set(CMAKE_FIND_ROOT_PATH  ~/crosscompile/sysroot)

# adjust the default behavior of the FIND_XXX() commands:
# search programs in the host environment
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)

# search headers and libraries in the target environment
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

set(CMAKE_SYSROOT ~/crosscompile/sysroot)

clone Repository

git clone https://github.com/HarbourMasters/2ship2harkinian
cd 2ship2harkinian
git submodule update --init

Quick ugly patch to compile OTR in case it fails because of a missing header

cd OTRExporter/OTRExporter
ln -s ~/crosscompile/sysroot/usr/local/include/tinyxml2.h tinyxml2.h
cd ../..

Generate MakeFiles using crosscompilation

cmake -H. -B build-cmake -GNinja -DUSE_OPENGLES=1 -DCMAKE_BUILD_TYPE:STRING=Release -DCMAKE_TOOLCHAIN_FILE=~/crosscompile/crosscompile.cmake

Build 2s2h.elf file

cmake --build build-cmake --config Release -j$(nproc)

Strip it

cd build-cmake/mm
aarch64-linux-gnu-strip 2s2h.elf

copy 2s2h.elf

To get 2s2h.o2r file Generate MakeFiles without crosscompilation

cd ~/crosscompile/2ship2harkinian
cmake -H. -B build-cmake_host -GNinja -DUSE_OPENGLES=1 -DCMAKE_BUILD_TYPE:STRING=Release
cmake --build build-cmake_host --config Release --target Generate2ShipOtr -j$(nproc)
cd build-cmake_host/mm

copy 2s2h.o2r