Application Notes: Developing with Qt on CompuLab platforms

Introduction

Development of Qt based applications for Embedded Linux systems often needs to be done on a host machine with a different architecture. The following document outlines the configuration steps required in order to prepare the host machine for cross-compiling. This manual outlines two alternative methods of using Yocto SDK for Qt development:

• Using Yocto SDK without QtCreator
• Using Yocto SDK with QtCreator

Setting up Qt Development Environment

Setup Yocto SDK with Qt support

• Setup Yocto SDK with Qt support as detailed at Yocto SDK with Qt5 support.

The following manual assumes that the SDK install path is `/opt/fsl-imx-xwayland/4.14-sumo`.

Setup Qt Environment

• Obtain a Linux Debian/Ubuntu desktop
• Install build-essential:

sudo apt-get install build-essential

• Install QtCreator:

sudo apt-get install qtcreator

• Make sure that Yocto SDK with Qt5 support is installed:

[[ -f /opt/fsl-imx-xwayland/4.14-sumo/environment-setup-aarch64-poky-linux ]] && echo "Installed" || echo "Not Installed"

• Make sure that the Qt5 support is enabled:

[[ -f /opt/fsl-imx-xwayland/4.14-sumo/sysroots/x86_64-pokysdk-linux/usr/bin/qt5/qmake ]] && echo "enabled" || echo "off"

Using Yocto SDK without QtCreator

• Open a terminal window and source the cross compiling environment setup:

. /opt/fsl-imx-xwayland/4.14-sumo/environment-setup-aarch64-poky-linux

• Make the Qt5 SDK examples available for the developer:

sudo chown ${USER}:${GROUPS} -R /opt/fsl-imx-xwayland/4.14-sumo/sysroots/aarch64-poky-linux/usr/share/qt5/examples

• Go to opengl/hellogl2 project directory:

cd /opt/fsl-imx-xwayland/4.14-sumo/sysroots/aarch64-poky-linux/usr/share/qt5/examples/opengl/hellogl2

• Issue the following sequence:

qmake -config release
make -j 8

• Issue `file` command and make sure that the produced binary is a valid ARM64 executable:

file hellogl2 | grep -q aarch64 && echo "good" || echo "bad"

• If the file is good, copy this binary file to the target device and run it.
• If the file is bad, re-issue the entire procedure .

Using Yocto SDK with QtCreator

Configuring QtCreator for use with Yocto SDK

The following example shows how to setup QtCreator with Yocto Project SDK built using Sumo distribution for a Linux x86_64 host:

• Open a terminal application and source the cross compiling environment setup with:

  . /opt/fsl-imx-xwayland/4.14-sumo/environment-setup-aarch64-poky-linux

• Start QtCreator in the same terminal window:

  qtcreator

• Open the Tools, Options... menu and select the Kits section
• Use the following line as qmake location in Qt versions tab:

  /opt/fsl-imx-xwayland/4.14-sumo/sysroots/x86_64-pokysdk-linux/usr/bin/qt5/qmake

• Use the following line as C++ compiler path and select ABI arm-linux-generic-elf-64bit in the Compilers tab:

  /opt/fsl-imx-xwayland/4.14-sumo/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gcc

• Use the following line as C++ compiler path and select ABI arm-linux-generic-elf-64bit in the Compilers tab:

  /opt/fsl-imx-xwayland/4.14-sumo/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-g++

• Use the following line as debugger path in Debuggers tab:

  /opt/fsl-imx-xwayland/4.14-sumo/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gdb

• Open the Devices section
• Create a new device of type Generic Linux Device in the Devices tab , specify IP address and authentication details:

• Return to the Kits section
• Create a new kit with name X-compile ARM 64bit selecting the configurations we just created

Use the following line as sysroot path:

/opt/fsl-imx-xwayland/4.14-sumo/sysroots/aarch64-poky-linux

• Click Apply and exit Qt Creator

QtCreator configuration screenshots

• 

  Qtc qmake

• 

  Qtc gcc

• 

  Qtc g

• 

  Qtc gdb

• 

  Qtc target

• 

  Qtc kit

Building a project using QtCreator

Make sure that the Configuring QtCreator for use with Yocto SDK was carried out first.

• Open a terminal window and source the cross compiling environment setup:

. /opt/fsl-imx-xwayland/4.14-sumo/environment-setup-aarch64-poky-linux

• Start QtCreator in the same terminal window:

qtcreator

• Create a new example project using the Qt Widgets Application template
• Name the project hello-qt
• Select the X-compile ARM 64bit kit we just created and finish
• Edit the hello-qt.pro adding:

# install
target.path=/home/root/
INSTALLS += target

• Build the project