Crosscompiling

Warning! You are in for a treat! :D - You have been warned. But reward is good, from 3250sec with docker buildx using qemu to 304s on my machine (Clean build)

PLEASE DONT RUN ANY SCRIPTS AS SUDO / ROOT! MY CODE IS NOT "SAFE"!

Instead give yourself write-access to /opt, sudo chmod 777 /opt/ for example.

Instructions

These instructions are made for Ubuntu 20.04.6 LTS

INSTALL ROS https://wiki.ros.org/noetic/Installation/Ubuntu

Update source files

• Add [arch=amd64] after deb on each line in /etc/apt/sources.list (This should be changed to your current machines native arch!)
• Add [arch=amd64,arm64] after deb in /etc/apt/sources.list.d/ros-latest.list

• Create /etc/apt/sources.list.d/arm-cross-compile-sources.list

deb [arch=arm64] http://ports.ubuntu.com/ focal main restricted
deb [arch=arm64] http://ports.ubuntu.com/ focal-updates main restricted
deb [arch=arm64] http://ports.ubuntu.com/ focal universe
deb [arch=arm64] http://ports.ubuntu.com/ focal-updates universe
deb [arch=arm64] http://ports.ubuntu.com/ focal multiverse
deb [arch=arm64] http://ports.ubuntu.com/ focal-updates multiverse
deb [arch=arm64] http://ports.ubuntu.com/ focal-backports main restricted universe multiverse

• run

sudo apt update
sudo dpkg --add-architecture arm64

sudo apt install crossbuild-essential-arm64 parallel

• Clone open_mower_ros and its componnets.

cd /opt/

git clone https://github.com/ClemensElflein/open_mower_ros
git submodule update --init --recursive

We will use CMAKE_SYSROOT /opt/sysroot_arm64 and /opt/sysroot_arm64_download - change these accordingly in the files for your needs. Total size to download is about 200MB and extracted is ~1.1GB. Change the number of download threads as desired.

• create toolchain.cmake

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_VERSION 1)
set(CMAKE_SYSTEM_PROCESSOR aarch64)

# Specify the cross compiler
set(CMAKE_C_COMPILER aarch64-linux-gnu-gcc)
set(CMAKE_CXX_COMPILER aarch64-linux-gnu-g++)

#set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static")
#set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -static")

# Specify the target system root
set(CMAKE_SYSROOT /opt/sysroot_arm64)

set(SYSROOT_PATH ${CMAKE_SYSROOT})

unset(CMAKE_SYSTEM_PREFIX_PATH)
list(APPEND CMAKE_SYSTEM_PREFIX_PATH ${CMAKE_SYSROOT}/opt/ros/noetic)

set(CMAKE_PREFIX_PATH ${CMAKE_SYSROOT}/opt/ros/noetic ${CMAKE_SYSROOT}/opt/ros/noetic/share)
set(CMAKE_LIBRARY_PATH ${CMAKE_SYSROOT}/opt/ros/noetic/lib)
set(CMAKE_INCLUDE_PATH ${CMAKE_SYSROOT}/opt/ros/noetic/include)
set(CMAKE_FIND_ROOT_PATH ${CMAKE_SYSROOT})

# Search for programs in the build host directories
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)

# For libraries and headers in the target directories
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

set(CMAKE_MODULE_PATH ${CMAKE_SYSROOT}/usr/share/cmake-3.13/Modules/)
set(ENV{PKG_CONFIG_PATH} ${CMAKE_SYSROOT}/usr/lib/aarch64-linux-gnu/pkgconfig/)

• create 1_setup-sysroot.bash

#!/bin/bash

set -e

SYSROOT=/opt/sysroot_arm64
DOWNLOADDIR=/opt/sysroot_downloads
PARALLELDOWNLOAD=6

#########################

rm -rf $SYSROOT
mkdir -p $SYSROOT
mkdir -p $DOWNLOADDIR

# Link might not be needed? Cant remember :D
ln -s $SYSROOT/usr/lib $SYSROOT/lib

install_package() {
#  for PKG in "${PACKAGES[@]}"; do
    PKG=$1
    URL=$(apt-get download --print-uris $PKG | cut -d\' -f2)
    if [ -n "$URL" ]; then
      echo "Downloading $PKG ($URL)"
      wget -q -nc $URL -P $DOWNLOADDIR && dpkg -x $DOWNLOADDIR/$(basename $URL) $SYSROOT
# --show-progress
#      dpkg -x $DOWNLOADDIR/$(basename $URL) $SYSROOT
      echo "Done installing $PKG"
    else
      echo "$PKG NOT FOUND!"
    fi
#  done
}

export -f install_package
export DOWNLOADDIR
export SYSROOT

# read packages.txt into PACKAGES
while IFS= read -r line; do
    PACKAGES+=("$line")
done < "packages.txt"


parallel -j $PARALLELDOWNLOAD install_package ::: "${PACKAGES[@]}"


echo "Done!"

• Download my little packages.txt # Focal Ubuntu 20.04.6 LTS!

wget https://gist.githubusercontent.com/Damme/3161f92ccadf452b4d5f3eee32da097e/raw/8df0172858e95da76091b04f8492705fc0cf0396/packages.txt -O packages.txt

• create 2-fix-links-cmake.bash

SYSROOT=/opt/sysroot_arm64

echo "Linking some missing library links, broken links /hardcoded to /lib/..."

ln -sf $SYSROOT/usr/lib/aarch64-linux-gnu/libPocoFoundation.so.62 $SYSROOT/usr/lib/aarch64-linux-gnu/libPocoFoundation.so
ln -sf $SYSROOT/usr/lib/aarch64-linux-gnu/blas/libblas.so.3 $SYSROOT/usr/lib/aarch64-linux-gnu/libblas.so.3
ln -sf $SYSROOT/usr/lib/aarch64-linux-gnu/lapack/liblapack.so.3 $SYSROOT/usr/lib/aarch64-linux-gnu/liblapack.so.3

ln -sf $SYSROOT/lib/aarch64-linux-gnu/librt.so.1 $SYSROOT/sysroot_arm64/usr/lib/aarch64-linux-gnu/librt.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libpthread.so.0 $SYSROOT/usr/lib/aarch64-linux-gnu/libpthread.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libBrokenLocale.so.1 $SYSROOT/usr/lib/aarch64-linux-gnu/libBrokenLocale.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libanl.so.1 $SYSROOT/usr/lib/aarch64-linux-gnu/libanl.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libblkid.so.1.1.0 $SYSROOT/usr/lib/aarch64-linux-gnu/libblkid.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libbz2.so.1.0 $SYSROOT/usr/lib/aarch64-linux-gnu/libbz2.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libexpat.so.1.6.11 $SYSROOT/usr/lib/aarch64-linux-gnu/libexpat.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libgpg-error.so.0 $SYSROOT/usr/lib/aarch64-linux-gnu/libgpg-error.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libkeyutils.so.1 $SYSROOT/usr/lib/aarch64-linux-gnu/libkeyutils.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/liblzma.so.5.2.4 $SYSROOT/usr/lib/aarch64-linux-gnu/liblzma.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libm.so.6 $SYSROOT/usr/lib/aarch64-linux-gnu/libm.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libmount.so.1.1.0 $SYSROOT/usr/lib/aarch64-linux-gnu/libmount.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libnsl.so.1 $SYSROOT/usr/lib/aarch64-linux-gnu/libnsl.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libnss_compat.so.2 $SYSROOT/usr/lib/aarch64-linux-gnu/libnss_compat.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libnss_dns.so.2 $SYSROOT/usr/lib/aarch64-linux-gnu/libnss_dns.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libnss_files.so.2 $SYSROOT/usr/lib/aarch64-linux-gnu/libnss_files.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libnss_hesiod.so.2 $SYSROOT/usr/lib/aarch64-linux-gnu/libnss_hesiod.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libnss_nis.so.2 $SYSROOT/usr/lib/aarch64-linux-gnu/libnss_nis.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libnss_nisplus.so.2 $SYSROOT/usr/lib/aarch64-linux-gnu/libnss_nisplus.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libpcre.so.3 $SYSROOT/usr/lib/aarch64-linux-gnu/libpcre.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libresolv.so.2 $SYSROOT/usr/lib/aarch64-linux-gnu/libresolv.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libthread_db.so.1 $SYSROOT/usr/lib/aarch64-linux-gnu/libthread_db.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libutil.so.1 $SYSROOT/usr/lib/aarch64-linux-gnu/libutil.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libuuid.so.1.3.0 $SYSROOT/usr/lib/aarch64-linux-gnu/libuuid.so
ln -sf $SYSROOT/lib/aarch64-linux-gnu/libz.so.1.2.11 $SYSROOT/usr/lib/aarch64-linux-gnu/libz.so

echo "Fix cmake files with hardcoded paths.."
find $SYSROOT/opt/ros/noetic/ -name "*.cmake" | xargs sed -i s@/opt/ros/noetic/lib@\${SYSROOT_PATH}/opt/ros/noetic/lib@g
find $SYSROOT/opt/ros/noetic/ -name "*.cmake" | xargs sed -i s@PREFIX\ /opt/ros/noetic@PREFIX\ \${SYSROOT_PATH}/opt/ros/noetic@g
find $SYSROOT/opt/ros/noetic/ -name "*.cmake" | xargs sed -i s@\;/usr/@\;\$\{SYSROOT_PATH\}/usr/@g
find $SYSROOT/opt/ros/noetic/ -name "*.cmake" | xargs sed -i s@\"/usr/@\"\$\{SYSROOT_PATH\}/usr/@g

• create 3-patch-openmower-cmake.bash

#!/bin/bash

cd src/lib/slic3r_coverage_planner

patch CMakeLists.txt <<'EOF'
@@ -33,7 +33,9 @@ ExternalProject_Add(

         CMAKE_CACHE_ARGS
         SOURCE_SUBDIR src
-        CMAKE_ARGS -DSLIC3R_BUILD_TESTS=OFF
+        CMAKE_ARGS -DSLIC3R_BUILD_TESTS=OFF -DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}
+               -DCMAKE_EXE_LINKER_FLAGS:STRING=--sysroot=${CMAKE_SYSROOT}\;-L${CMAKE_SYSROOT}/opt/ros/noetic/lib\;-L${CMAKE_SYSROOT}/usr/lib/aarch64-linux-gnu
+               -DCMAKE_SHARED_LINKER_FLAGS:STRING=--sysroot=${CMAKE_SYSROOT}\;-L${CMAKE_SYSROOT}/opt/ros/noetic/lib\;-L${CMAKE_SYSROOT}/usr/lib/aarch64-linux-gnu
         BUILD_COMMAND ${CMAKE_COMMAND} --build <BINARY_DIR> --config Release
 )
EOF

cd ../../../

cd src/lib/xbot_driver_gps

patch CMakeLists.txt <<'EOF'
@@ -32,6 +32,9 @@ ExternalProject_Add(
         INSTALL_COMMAND cmake -E echo "Skipping install step."

         CMAKE_CACHE_ARGS
+        CMAKE_ARGS -DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}
+               -DCMAKE_EXE_LINKER_FLAGS:STRING=--sysroot=${CMAKE_SYSROOT}\;-L${CMAKE_SYSROOT}/opt/ros/noetic/lib\;-L${CMAKE_SYSROOT}/usr/lib/aarch64-linux-gnu
+               -DCMAKE_SHARED_LINKER_FLAGS:STRING=--sysroot=${CMAKE_SYSROOT}\;-L${CMAKE_SYSROOT}/opt/ros/noetic/lib\;-L${CMAKE_SYSROOT}/usr/lib/aarch64-linux-gnu
         BUILD_COMMAND ${CMAKE_COMMAND} --build <BINARY_DIR> --config Release
 )
EOF

cd ../../../

• run the following:

bash 1-setup_sysroot.bash
bash 2-fix-links-cmake.bash
bash 3-patch-openmower-cmake.bash

• build with the following command, change -j1 for number of parallel processes. For some reason catkin_make does not parse toolchain.cmake without forcing it...

$ catkin_make -DCMAKE_TOOLCHAIN_FILE=/opt/open_mower_ros/toolchain.cmake -j1

Good luck!