RaspberryPiWithQt6WebEngine: Difference between revisions

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In this guide we are going to cross compile Qt 6.5 with WebEngine coming from Qt 6.7
In this guide we are going to cross compile Qt 6.5 with WebEngine coming from Qt 6.7


{{note | As shown [[Cross-Compile_Qt_6_for_Raspberry_Pi | here]], we could do a top level build of Qt6, but we are going to do prefix module builds just to show an alternative way of building Qt6.}}
{{note | As shown [[Cross-Compile_Qt_6_for_Raspberry_Pi | here]], we could do a 'top level build' of Qt6, but we are going to do 'prefix module build' just to show an alternative way of building Qt6.}}


We need fours repositories to have Qt 6WebEngine up and running: qtbase, shadertools, qtdeclarative and qtwebengine.
We need fours repositories to have Qt 6WebEngine up and running: qtbase, shadertools, qtdeclarative and qtwebengine.

Revision as of 16:46, 4 January 2024

Introduction

This page describes how to set up self-compiled Qt6 with WebEngine on Raspberry Pi 4 running Raspberry Pi OS.

To see other guides visit:

Setup

To be able to cross compile Qt6 for Raspberry Pi OS, we need three things:

Qt6 uses cmake therefore to cross-compile we need to have actually two builds of Qt. One Qt6 host build, which is later used to cross-compile the arm64 Qt build.

In this guide we are going to cross compile Qt 6.5 with WebEngine coming from Qt 6.7

  Note: As shown here, we could do a 'top level build' of Qt6, but we are going to do 'prefix module build' just to show an alternative way of building Qt6.

We need fours repositories to have Qt 6WebEngine up and running: qtbase, shadertools, qtdeclarative and qtwebengine.

  • Let's create our workspace:
    mkdir -p ~/workspaces/rpi/host
    mkdir -p ~/workspaces/rpi/host/sysroot
    mkdir -p ~/workspaces/rpi/host/qt
    mkdir -p ~/workspaces/rpi/target
    mkdir -p ~/workspaces/rpi/image
    
  • Let's checkout qt source code and select branches:
    cd ~/workspaces/rpi/host/qt
    git clone git://code.qt.io/qt/qtbase.git
    cd qtbase
    git git checkout origin/6.5.3
    cd ..
    
    git clone git://code.qt.io/qt/qtshadertools.git
    cd qtshadertools
    git checkout origin/6.5.3
    cd ..
    
    git clone git://code.qt.io/qt/qtdeclarative.git
    cd qtdeclarative
    git checkout origin/6.5.3
    cd ..
    
    git clone git://code.qt.io/qt/qtwebengine.git
    git checkout origin/6.7
    git submodule update
    cd ..
    

  Note: QtWebEngine needs initialization of the submodule.

Sysroot

To be able to cross-compile, we need a part of arm64 target sysroot to be present on our build machine. As shown here, you could simply start your Rasberry Pi OS on the board and then rsync the required libs and includes to the host machine with SSH connection. However, in this guide we will mount the Raspberry Pi OS image via a loop device, use qemu to install build dependencies and than make a local copy.

  Note: We do need a local copy of 'libs' and 'headers' from the image, as we want to adjust the symlinks.

  • Let's now download Raspberry Pi OS:
    cd ~/workspaces/rpi/image
    wget https://downloads.raspberrypi.com/raspios_arm64/images/raspios_arm64-2023-12-06/2023-12-05-raspios-bookworm-arm64.img.xz
    
  • Let's extract the image:
    unxz --keep 2023-12-05-raspios-bookworm-arm64.img.xz
    
  • We need add at least 2G space to the image to be able to fit qt build with debug info (see here instructions)
  • Make loop devices for the image:
    losetup -fP 2023-12-05-raspios-bookworm-arm64.img
    losetup -a
    /dev/loop0: [66306]:2363198 (~/workspaces/rpi/image/2023-12-05-raspios-bookworm-arm64.img)
    
  • Mount the root partition:
    mount /dev/loop0p2 -t ext4 ~/workspaces/rpi/target
    mount -t proc /proc ~/workspaces/rpi/target/proc
    mount -t sysfs /sys ~/workspaces/rpi/target/sys
    mount --bind /dev ~/workspaces/rpi/target/dev
    mount --bind /dev/pts ~/workspaces/rpi/target/pts
    
  • We need qemu on the image to able to execute command, therefore copy static qemu binary to image.
    cp /usr/bin/qemu-arch64-static /workspaces/rpi/target/usr/bin/
    

  Note: Setup of qemu static interpreter is distribution specific. Please refer to your Linux distribution documentation.

  • Chroot to arm64 target:
    cd ~/workspaces/rpi/target
    chroot .
    
  • Let's update Qt6 build dependencies:
    vi /etc/apt/sources.list
    # uncomment the deb-src line
    apt update
    apt build-dep qt6-base
    exit
    
  • rsync the parts that we need:
    cd ~/workspaces/rpi/host
    rsync -av ~/workspaces/rpi/target/lib sysroot
    rsync -av ~/workspaces/rpi/target/usr/include sysroot/usr
    rsync -av ~/workspaces/rpi/target/usr/lib sysroot/usr
    
  • Adjust symlinks to be relative:
    wget https://raw.githubusercontent.com/Kukkimonsuta/rpi-buildqt/master/scripts/utils/sysroot-relativelinks.py
    chmod +x sysroot-relativelinks.py
    ./sysroot-relativelinks.py sysroot
    

  Note: Command-line tool called symlinks should not be used instead as it creates dangling links.

  • Umount no longer needed mounts:
    umount ~/workspaces/rpi/target/sys ~/workspaces/rpi/target/proc 
    umount ~/workspaces/rpi/target/dev/pts ~/workspaces/rpi/target/dev
    
  • Detach loop device:
    losetup -d /dev/loop0
    

Toolchain

To cross-compile Qt, we need a cross-compiler toolchain. There are many excellent tools to compile a toolchain, such as crosstool-ng or buildroot. We could also simply download ready 3dparty toolchain form the internet. However, this guide will use the official gcc cross compiler, which is shipped with Debian distribution, same as the one shipped with Raspberry Pi OS. In time of writing this quide latest Raspberry Pi OS is called 'Bookworm' and it is shipped with gcc 12.2 and Qt 6.4. Therefore we will use the gnu gcc cross compiler from Bookworm release. To setup the cross-compiler toolchain will use 'debootstrap' which is a very convenient tool to install Debian base system into a subdirectory of any other running Linux system. Most of distributions ship this tool therefore it was selected as most generic approach.

  Note: The other approach could be for example installing Debian distribution on VM.

  • To setup Bookworm Debian release on your machine execute:
    cd ~/workspaces/rpi/host
    debootstrap --arch amd64 bookworm ~/workspace/rpi/host http://ftp.uk.debian.org/debian
    
  • Let's mount and chroot into newly created installation:
    mount -t proc /proc ~/workspaces/rpi/host/proc
    mount -t sysfs /sys ~/workspaces/rpi/host/sys
    mount --bind /dev ~/workspaces/rpi/host/dev
    mount --bind /dev/pts ~/workspaces/rpi/target/pts
    
    chroot ~/workspaces/rpi/host /bin/bash
    
  • Let's install host and cross compiler:
    apt install build-essential crossbuild-essential-arm64
    

Qt6 Host Build

  Note: After toolchain setup, we should be chrooted into our host Debian root (~/workspaces/rpi/host).

  • Let's install dependencies for build using know dependencies for Qt 6.4:
    vi /etc/apt/sources.list
    apt update
    apt build-dep qt6-base
    
  • Let's configure host build for Qt6 qtbase, build it and install into ~/workspaces/rpi/host/opt/qt:
    cd /qt/build
    mkdir qtbase
    cd qtbase 
    /qt/qtbase/configure -release -nomake tests -nomake examples -linker lld -prefix /opt/qt
    cmake --build . --parallel
    cmake --install
    

  Note: /qt/qtbase is really ~/workspaces/rpi/host/qt/qtbase on build machine