Qt 6.8 Cross-Compilation for Raspberry Pi Embedded Software

Introduction

In a previous series of blogposts

I wrote about the installation of Raspbian on Raspberry Compute Module and setup cross compilation for QtCreator on Ubuntu 20.

This blogpost is an update to the - at this time - newest version 6.8 of Qt, raspi OS Bookworm and Ubuntu 22.04 LTS.

Prerequisites

I used the following hard- and software:

Raspberry Pi 4
raspi OS Bookworm, without recommended software
Ubuntu 22.04 LTS
Qt 6.8
QtCreator 14.02

Notes

If you have a laptop or desktop computer with enough RAM and CPU cores, you can do the cross compilation in a virtual machine. But I made the experience, that a native computer is much faster and produces less errors.

Have a look at the file paths and ip addresses in my code examples and adjust them to your needs.

Setup Raspberry Pi

Download raspiOS from https://www.raspberrypi.com/software/operating-systems
2024-07-04-raspios-bookworm-arm64.img.xz: 64bit with Raspberry Pi OS with desktop (not with recommended Software)
Flash image to SD-card with Balena Etcher
Follow the installation and don't forget the setting for remote connect (ssh)
Connect to the RPi with ssh -> in my case to IP address 192.168.2.167 and user pi -> from your Ubuntu host

ssh [email protected]

Install needed software:

sudo apt-get install libboost-all-dev libudev-dev libinput-dev libts-dev libmtdev-dev libjpeg-dev libfontconfig1-dev libssl-dev libdbus-1-dev libglib2.0-dev libxkbcommon-dev libegl1-mesa-dev libgbm-dev libgles2-mesa-dev mesa-common-dev libasound2-dev libpulse-dev gstreamer1.0-omx libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev  gstreamer1.0-alsa libvpx-dev libsrtp2-dev libsnappy-dev libnss3-dev "^libxcb.*" flex bison libxslt-dev ruby gperf libbz2-dev libcups2-dev libatkmm-1.6-dev libxi6 libxcomposite1 libfreetype6-dev libicu-dev libsqlite3-dev libxslt1-dev

sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libx11-dev freetds-dev libsqlite3-dev libpq-dev libiodbc2-dev firebird-dev libxext-dev libxcb1 libxcb1-dev libx11-xcb1 libx11-xcb-dev libxcb-keysyms1 libxcb-keysyms1-dev libxcb-image0 libxcb-image0-dev libxcb-shm0 libxcb-shm0-dev libxcb-icccm4 libxcb-icccm4-dev libxcb-sync1 libxcb-sync-dev libxcb-render-util0 libxcb-render-util0-dev libxcb-xfixes0-dev libxrender-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-glx0-dev libxi-dev libdrm-dev libxcb-xinerama0 libxcb-xinerama0-dev libatspi2.0-dev libxcursor-dev libxcomposite-dev libxdamage-dev libxss-dev libxtst-dev libpci-dev libcap-dev libxrandr-dev libdirectfb-dev libaudio-dev libxkbcommon-x11-dev gdbserver

Make a folder for Qt 6 installation:

sudo mkdir /usr/local/qt6

Discover versions of gcc, ld and ldd. Source code of the same version should be downloaded to build cross compiler later.

pi@raspberrypi:~ $ gcc --version
gcc (Debian 12.2.0-14) 12.2.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

pi@raspberrypi:~ $ ld --version
GNU ld (GNU Binutils for Debian) 2.40
Copyright (C) 2023 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
This program has absolutely no warranty.

pi@raspberrypi:~ $ ldd --version
ldd (Debian GLIBC 2.36-9+rpt2+deb12u8) 2.36
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Written by Roland McGrath and Ulrich Drepper.

Append following piece of code to the end of ~/.bashrc and update changes:

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/qt6/lib/
source ~/.bashrc

Setup Ubuntu 22.04 LTS

Update to the latest versions of the software packages:

sudo apt update
sudo apt upgrade

Install the following packages:

sudo apt-get install make build-essential libclang-dev ninja-build gcc git bison python3 gperf pkg-config libfontconfig1-dev libfreetype6-dev libx11-dev libx11-xcb-dev libxext-dev libxfixes-dev libxi-dev libxrender-dev libxcb1-dev libxcb-glx0-dev libxcb-keysyms1-dev libxcb-image0-dev libxcb-shm0-dev libxcb-icccm4-dev libxcb-sync-dev libxcb-xfixes0-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-render-util0-dev libxcb-util-dev libxcb-xinerama0-dev libxcb-xkb-dev libxkbcommon-dev libxkbcommon-x11-dev libatspi2.0-dev libgl1-mesa-dev libglu1-mesa-dev freeglut3-dev build-essential gawk git texinfo bison file wget libssl-dev gdbserver gdb-multiarch libxcb-cursor-dev

Build the latest cmake version from source:

cd ~
wget https://github.com/Kitware/CMake/releases/download/v3.30.5/cmake-3.30.5.tar.gz
tar -xzvf cmake-3.30.5.tar.gz
cd cmake-3.30.5
./bootstrap
make -j$(nproc)
sudo make install
# Update PATH Environment Variable
which cmake
/usr/local/bin/cmake
export PATH=/usr/local/bin/cmake:$PATH
source ~/.bashrc
cmake --version

Build gcc as a cross compiler

Download necessary source code. You should modify the following commands to your needs. For the time I make this page, they are:

gcc 12.2.0
binutils 2.40(ld version)
glibc 2.36(ldd version)

cd ~
mkdir gcc_all && cd gcc_all
wget https://ftpmirror.gnu.org/binutils/binutils-2.40.tar.bz2
wget https://ftpmirror.gnu.org/glibc/glibc-2.36.tar.bz2
wget https://ftpmirror.gnu.org/gcc/gcc-12.2.0/gcc-12.2.0.tar.gz
git clone --depth=1 https://github.com/raspberrypi/linux
tar xf binutils-2.40.tar.bz2
tar xf glibc-2.36.tar.bz2
tar xf gcc-12.2.0.tar.gz
rm *.tar.*
cd gcc-12.2.0
contrib/download_prerequisites

Make a folder for the compiler installation.

sudo mkdir -p /opt/cross-pi-gcc
sudo chown $USER /opt/cross-pi-gcc
export PATH=/opt/cross-pi-gcc/bin:$PATH

Copy the kernel headers in the above folder.

cd ~/gcc_all
cd linux
KERNEL=kernel7
make ARCH=arm64 INSTALL_HDR_PATH=/opt/cross-pi-gcc/aarch64-linux-gnu headers_install

Build Binutils.

cd ~/gcc_all
mkdir build-binutils && cd build-binutils
../binutils-2.40/configure --prefix=/opt/cross-pi-gcc --target=aarch64-linux-gnu --with-arch=armv8 --disable-multilib
make -j 8
make install

Edit gcc-12.2.0/libsanitizer/asan/asan_linux.cpp. Add following piece of code.

#ifndef PATH_MAX
#define PATH_MAX 4096
#endif

Do a partial build of gcc.

cd ~/gcc_all
mkdir build-gcc && cd build-gcc
../gcc-12.2.0/configure --prefix=/opt/cross-pi-gcc --target=aarch64-linux-gnu --enable-languages=c,c++ --disable-multilib
make -j8 all-gcc
make install-gcc

Partially build Glibc.

cd ~/gcc_all
mkdir build-glibc && cd build-glibc
../glibc-2.36/configure --prefix=/opt/cross-pi-gcc/aarch64-linux-gnu --build=$MACHTYPE --host=aarch64-linux-gnu --target=aarch64-linux-gnu --with-headers=/opt/cross-pi-gcc/aarch64-linux-gnu/include --disable-multilib libc_cv_forced_unwind=yes
make install-bootstrap-headers=yes install-headers
make -j8 csu/subdir_lib
install csu/crt1.o csu/crti.o csu/crtn.o /opt/cross-pi-gcc/aarch64-linux-gnu/lib
aarch64-linux-gnu-gcc -nostdlib -nostartfiles -shared -x c /dev/null -o /opt/cross-pi-gcc/aarch64-linux-gnu/lib/libc.so
touch /opt/cross-pi-gcc/aarch64-linux-gnu/include/gnu/stubs.h

Back to gcc.

cd ~/gcc_all/build-gcc
make -j8 all-target-libgcc
make install-target-libgcc

Finish building glibc.

cd ~/gcc_all/build-glibc
make -j8
make install

Finish building gcc.

cd ~/gcc_all/build-gcc
make -j8
make install

At this point, we have a full cross compiler toolchain with gcc. Folder gcc_all is not need any more. You can delete it.

Building Qt6

There are two possibilities to build Qt6. There is a "single" (https://download.qt.io/official_releases/qt/6.8/6.8.0/single/qt-everywhere-src-6.8.0.tar.xz) version to download, which contains qtbase and all submodules. This is very heavy stuff and needs much power and time to compile it.

My recommendation is, to compile qtbase as basis and afterwards compile only each submodule you need separately.

Make folders for sysroot and qt6. I create this folders in my workspace/qt-rpi-cross-compilation directory.

cd ~/workspace/qt-rpi-cross-compilation
mkdir rpi-sysroot rpi-sysroot/usr rpi-sysroot/opt
mkdir qt6 qt6/host qt6/pi qt6/host-build qt6/pi-build qt6/src

Download QtBase source code

cd ~/workspace/qt-rpi-cross-compilation/qt6/src
wget https://download.qt.io/official_releases/qt/6.8/6.8.0/submodules/qtbase-everywhere-src-6.8.0.tar.xz
tar xf qtbase-everywhere-src-6.8.0.tar.xz

Build Qt6 for host

cd ~/workspace/qt-rpi-cross-compilation/qt6/host-build/
cmake ../src/qtbase-everywhere-src-6.8.0/ -GNinja -DCMAKE_BUILD_TYPE=Release -DQT_BUILD_EXAMPLES=OFF -DQT_BUILD_TESTS=OFF -DCMAKE_INSTALL_PREFIX=$HOME/qt6/host
cmake --build . --parallel 8
cmake --install .

Binaries will be in ~/workspace/qt-rpi-cross-compilation/qt6/host

Build Qt6 for rpi

Copy and paste a few folders from rpi using rsync through SSH.

cd ~
rsync -avz --rsync-path="sudo rsync" [email protected]:/usr/include workspace/qt-rpi-cross-compilation/rpi-sysroot/usr
rsync -avz --rsync-path="sudo rsync" [email protected]:/lib workspace/qt-rpi-cross-compilation/rpi-sysroot
rsync -avz --rsync-path="sudo rsync" [email protected]:/usr/lib workspace/qt-rpi-cross-compilation/rpi-sysroot/usr 
rsync -avz --rsync-path="sudo rsync" [email protected]:/opt/vc workspace/qt-rpi-cross-compilation/rpi-sysroot/opt

Create a file named toolchain.cmake in ~/workspace/qt-rpi-cross-compilation/qt6. You need to adjust the line "set(TARGET_SYSROOT /home/factory/workspace/qt-rpi-cross-compilation/rpi-sysroot)" to your environment.

cmake_minimum_required(VERSION 3.18)
include_guard(GLOBAL)

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)

# You should change location of sysroot to your needs.
set(TARGET_SYSROOT /home/factory/workspace/qt-rpi-cross-compilation/rpi-sysroot)
set(TARGET_ARCHITECTURE aarch64-linux-gnu)
set(CMAKE_SYSROOT ${TARGET_SYSROOT})

set(ENV{PKG_CONFIG_PATH} $PKG_CONFIG_PATH:${CMAKE_SYSROOT}/usr/lib/${TARGET_ARCHITECTURE}/pkgconfig)
set(ENV{PKG_CONFIG_LIBDIR} /usr/lib/pkgconfig:/usr/share/pkgconfig/:${TARGET_SYSROOT}/usr/lib/${TARGET_ARCHITECTURE}/pkgconfig:${TARGET_SYSROOT}/usr/lib/pkgconfig)
set(ENV{PKG_CONFIG_SYSROOT_DIR} ${CMAKE_SYSROOT})

set(CMAKE_C_COMPILER /opt/cross-pi-gcc/bin/${TARGET_ARCHITECTURE}-gcc)
set(CMAKE_CXX_COMPILER /opt/cross-pi-gcc/bin/${TARGET_ARCHITECTURE}-g++)

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -isystem=/usr/include -isystem=/usr/local/include -isystem=/usr/include/${TARGET_ARCHITECTURE}")
set(CMAKE_CXX_FLAGS "${CMAKE_C_FLAGS}")

set(QT_COMPILER_FLAGS "-march=armv8-a")
set(QT_COMPILER_FLAGS_RELEASE "-O2 -pipe")
set(QT_LINKER_FLAGS "-Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed -Wl,-rpath-link=${TARGET_SYSROOT}/usr/lib/${TARGET_ARCHITECTURE} -Wl,-rpath-link=$HOME/qt6/pi/lib")

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)
set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
set(CMAKE_BUILD_RPATH ${TARGET_SYSROOT})

include(CMakeInitializeConfigs)

function(cmake_initialize_per_config_variable _PREFIX _DOCSTRING)
  if (_PREFIX MATCHES "CMAKE_(C|CXX|ASM)_FLAGS")
    set(CMAKE_${CMAKE_MATCH_1}_FLAGS_INIT "${QT_COMPILER_FLAGS}")
        
    foreach (config DEBUG RELEASE MINSIZEREL RELWITHDEBINFO)
      if (DEFINED QT_COMPILER_FLAGS_${config})
        set(CMAKE_${CMAKE_MATCH_1}_FLAGS_${config}_INIT "${QT_COMPILER_FLAGS_${config}}")
      endif()
    endforeach()
  endif()


  if (_PREFIX MATCHES "CMAKE_(SHARED|MODULE|EXE)_LINKER_FLAGS")
    foreach (config SHARED MODULE EXE)
      set(CMAKE_${config}_LINKER_FLAGS_INIT "${QT_LINKER_FLAGS}")
    endforeach()
  endif()

  _cmake_initialize_per_config_variable(${ARGV})
endfunction()

set(XCB_PATH_VARIABLE ${TARGET_SYSROOT})

set(GL_INC_DIR ${TARGET_SYSROOT}/usr/include)
set(GL_LIB_DIR ${TARGET_SYSROOT}:${TARGET_SYSROOT}/usr/lib/${TARGET_ARCHITECTURE}/:${TARGET_SYSROOT}/usr:${TARGET_SYSROOT}/usr/lib)

set(EGL_INCLUDE_DIR ${GL_INC_DIR})
set(EGL_LIBRARY ${XCB_PATH_VARIABLE}/usr/lib/${TARGET_ARCHITECTURE}/libEGL.so)

set(OPENGL_INCLUDE_DIR ${GL_INC_DIR})
set(OPENGL_opengl_LIBRARY ${XCB_PATH_VARIABLE}/usr/lib/${TARGET_ARCHITECTURE}/libOpenGL.so)

set(GLESv2_INCLUDE_DIR ${GL_INC_DIR})
set(GLIB_LIBRARY ${XCB_PATH_VARIABLE}/usr/lib/${TARGET_ARCHITECTURE}/libGLESv2.so)

set(GLESv2_INCLUDE_DIR ${GL_INC_DIR})
set(GLESv2_LIBRARY ${XCB_PATH_VARIABLE}/usr/lib/${TARGET_ARCHITECTURE}/libGLESv2.so)

set(gbm_INCLUDE_DIR ${GL_INC_DIR})
set(gbm_LIBRARY ${XCB_PATH_VARIABLE}/usr/lib/${TARGET_ARCHITECTURE}/libgbm.so)

set(Libdrm_INCLUDE_DIR ${GL_INC_DIR})
set(Libdrm_LIBRARY ${XCB_PATH_VARIABLE}/usr/lib/${TARGET_ARCHITECTURE}/libdrm.so)

set(XCB_XCB_INCLUDE_DIR ${GL_INC_DIR})
set(XCB_XCB_LIBRARY ${XCB_PATH_VARIABLE}/usr/lib/${TARGET_ARCHITECTURE}/libxcb.so)

list(APPEND CMAKE_LIBRARY_PATH ${CMAKE_SYSROOT}/usr/lib/${TARGET_ARCHITECTURE})
list(APPEND CMAKE_PREFIX_PATH "/usr/lib/${TARGET_ARCHITECTURE}/cmake")

Fix absolute symbolic links

cd ~/workspace/qt-rpi-cross-compilation
wget https://raw.githubusercontent.com/riscv/riscv-poky/master/scripts/sysroot-relativelinks.py
chmod +x sysroot-relativelinks.py 
python3 sysroot-relativelinks.py rpi-sysroot

Compile source code for rpi.

cd $HOME/workspace/qt-rpi-cross-compilation/qt6/pi-build
cmake ../src/qtbase-everywhere-src-6.8.0/ -GNinja -DCMAKE_BUILD_TYPE=Release -DINPUT_opengl=es2 -DQT_BUILD_EXAMPLES=OFF -DQT_BUILD_TESTS=OFF -DQT_HOST_PATH=$HOME/workspace/qt-rpi-cross-compilation/qt6/host -DCMAKE_STAGING_PREFIX=$HOME/workspace/qt-rpi-cross-compilation/qt6/pi -DCMAKE_INSTALL_PREFIX=/usr/local/qt6 -DCMAKE_TOOLCHAIN_FILE=$HOME/workspace/qt-rpi-cross-compilation/qt6/toolchain.cmake -DQT_QMAKE_TARGET_MKSPEC=devices/linux-rasp-pi4-aarch64 -DQT_FEATURE_xcb=ON -DFEATURE_xcb_xlib=ON -DQT_FEATURE_xlib=ON
cmake --build . --parallel 8
cmake --install .

Send the binaries to rpi.

rsync -avz --rsync-path="sudo rsync" $HOME/workspace/qt-rpi-cross-compilation/qt6/pi/* [email protected]:/usr/local/qt6

Configure QtCreator

Set up Compilers
Set up Debuggers
Set up Devices
Test the connection with the button "Test"
Set up Qt Versions
Set up Kits
On "CMake Configuration" click Change and add follow commands.

-DCMAKE_TOOLCHAIN_FILE:UNINITIALIZED=/home/pmy/qt6/pi/lib/cmake/Qt6/qt.toolchain.cmake

QtCreator Projects settings

If you create a project in QtCreator, you have to adjust the "Run" configuration. At "Environment" you have to add:

-LD_LIBRARY_PATH=:/usr/local/qt6/lib/

Add Qt Submodules

Add QML module

Download source codes:

cd ~/workspace/qt-rpi-cross-compilation/qt6/src
wget https://download.qt.io/official_releases/qt/6.8/6.8.0/submodules/qtshadertools-everywhere-src-6.8.0.tar.xz
tar xf qtshadertools-everywhere-src-6.8.0.tar.xz
wget https://download.qt.io/official_releases/qt/6.8/6.8.0/submodules/qtdeclarative-everywhere-src-6.8.0.tar.xz
tar xf qtdeclarative-everywhere-src-6.8.0.tar.xz

You have to check dependencies at ~/workspace/qt-rpi-cross-compilation/qt6/src/qtdeclarative-everywhere-src-6.8.0/dependencies.yaml and ~/workspace/qt-rpi-cross-compilation/qt6/src/qtshadertools-everywhere-src-6.8.0/dependencies.yaml.

Make sure required modules should be built and installed first.

Build the modules for host.

cd ~/workspace/qt-rpi-cross-compilation/qt6/host-build
rm -rf *
$HOME/workspace/qt-rpi-cross-compilation/qt6/host/bin/qt-configure-module ../src/qtshadertools-everywhere-src-6.8.0
cmake --build . --parallel 8
cmake --install .
rm -rf *
$HOME/workspace/qt-rpi-cross-compilation/qt6/host/bin/qt-configure-module ../src/qtdeclarative-everywhere-src-6.8.0
cmake --build . --parallel 8
cmake --install .

Build the modules for rpi

cd ~/workspace/qt-rpi-cross-compilation/qt6/pi-build
rm -rf *
$HOME/workspace/qt-rpi-cross-compilation/qt6/pi/bin/qt-configure-module ../src/qtshadertools-everywhere-src-6.8.0
cmake --build . --parallel 8
cmake --install .
rm -rf *
$HOME/workspace/qt-rpi-cross-compilation/qt6/pi/bin/qt-configure-module ../src/qtdeclarative-everywhere-src-6.8.0
cmake --build . --parallel 8
cmake --install .

Send the binaries to rpi.

rsync -avz --rsync-path="sudo rsync" $HOME/workspace/qt-rpi-cross-compilation/qt6/pi/* [email protected]:/usr/local/qt6

Acknowledgments

Sources used in to create this Instructions:

Thanks to all.

Introduction

Prerequisites

Notes

Setup Raspberry Pi

Setup Ubuntu 22.04 LTS

Build the latest cmake version from source:

Build gcc as a cross compiler

Building Qt6

Build Qt6 for host

Build Qt6 for rpi

Configure QtCreator

QtCreator Projects settings

Add Qt Submodules

Add QML module

Acknowledgments

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Start your Project now

Introduction

Prerequisites

Notes

Setup Raspberry Pi

Setup Ubuntu 22.04 LTS

Build the latest cmake version from source:

Build gcc as a cross compiler

Building Qt6

Build Qt6 for host

Build Qt6 for rpi

Configure QtCreator

QtCreator Projects settings

Add Qt Submodules

Add QML module

Acknowledgments

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Start your Project now