Ubuntu cross compiling with libraries

This guide describes how to cross compile for aarch64 targets with linking to external libraries from a Ubuntu host. The cross compilation is tested on a x86_64 host running Ubuntu 20.04, a target running Ubuntu Server 20.04 aarch64 (Raspberry Pi 4B) and using the cmake build tool. It links external libraries by mounting the target filesystem over sshfs

Install external libraries (OMPL: lib-eigen3-dev, boost libraries)

• Unordered List ItemInstall aarch64 compiler
  • sudo apt-get install g++-aarch64-linux-gnu

• Mount target filesystem
  • sudo mkdir /mnt/rpi
  • sudo sshfs -o allow_other,default_permissions [target_username]@[target_ip]:/ /mnt/rpi

• Create toolchain.cmake file, see section below.
• Configure cmake to use toolchain file
  • cmake -DCMAKE_TOOLCHAIN_FILE=..[toolchain_file] [project_location]
  • make -j[threads_to_use]

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR aarch64)

set(tools /usr/bin)
set(CMAKE_C_COMPILER ${tools}/aarch64-linux-gnu-gcc-9)
set(CMAKE_CXX_COMPILER ${tools}/aarch64-linux-gnu-g++-9)

set(CMAKE_SYSROOT /mnt/rpi)

set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)