Setting Up Embedded Linux Qt Environment

This article introduces how to configure the Qt runtime environment on an embedded Linux development board and perform Qt program running tests.

Setting Up Embedded Linux Qt Environment

1 Compiling tslib

I have used tslib previously for testing the touchscreen, and here I will record the compilation process.

Download the source code of tslib library: https://github.com/libts/tslib/tags

Copy the downloaded source code to the Ubuntu virtual machine, then extract:

tar xvf tslib-1.21.tar.bz2

Before compiling tslib, you need to install some files in Ubuntu:

sudo apt-get install autoconf 
sudo apt-get install automake 
sudo apt-get install libtool

Create a directory named “tslib” in Ubuntu to store the compilation results, then execute the following commands to compile:

./configure --host=arm-linux-gnueabihf ac_cv_func_malloc_0_nonnull=yes --cache-file=arm-linux.cache -prefix=/home/xxpcb/myTest/imx6ull/otherlib/tslib-2/tslib

make
make install

After compilation, make install will copy the compilation results to the specified tslib directory:

Setting Up Embedded Linux Qt Environment

Package the tslib folder into arm-tslib.tar.bz2 file for later use when porting to the development board:

tar -jcf arm-tslib.tar.bz2 tslib

2 Compiling Qt Source Code

2.1 Downloading Qt5 Source Code

Download link: https://download.qt.io/archive/qt/5.15/5.15.2/single/

Copy the downloaded qt-everywhere-src-5.15.2.tar.xz to Ubuntu, then extract:

tar -xvf qt-everywhere-src-5.15.2.tar.xz

2.2 Modifying qmake.conf

Modify the qtbase/mkspecs/linux-arm-gnueabi-g++/ qmake.conf file

The default content of this file is:

#
# qmake configuration for building with arm-linux-gnueabi-g++
#

MAKEFILE_GENERATOR      = UNIX
CONFIG                 += incremental
QMAKE_INCREMENTAL_STYLE = sublib

include(../common/linux.conf)
include(../common/gcc-base-unix.conf)
include(../common/g++-unix.conf)

# modifications to g++.conf
QMAKE_CC                = arm-linux-gnueabi-gcc
QMAKE_CXX               = arm-linux-gnueabi-g++
QMAKE_LINK              = arm-linux-gnueabi-g++
QMAKE_LINK_SHLIB        = arm-linux-gnueabi-g++

# modifications to linux.conf
QMAKE_AR                = arm-linux-gnueabi-ar cqs
QMAKE_OBJCOPY           = arm-linux-gnueabi-objcopy
QMAKE_NM                = arm-linux-gnueabi-nm -P
QMAKE_STRIP             = arm-linux-gnueabi-strip
load(qt_config)

Modify it to the following:

2.3 Configuring Compilation Options

Check the compilation options by entering ./configure -help command:

./configure -help

There are many configuration options, so a configuration script can be used.

Create an autoconfigure.sh file and write the following configuration based on your situation:

./configure -prefix /home/xxpcb/myTest/imx6ull/otherlib/qt/qt-everywhere-src-5.12.9/arm-qt \
-opensource \
-confirm-license \
-release \
-strip \
-shared \
-xplatform linux-arm-gnueabi-g++ \
-optimized-qmake \
-c++std c++11 \
--rpath=no \
-pch \
-skip qt3d \
-skip qtactiveqt \
-skip qtandroidextras \
-skip qtcanvas3d \
-skip qtconnectivity \
-skip qtdatavis3d \
-skip qtdoc \
-skip qtgamepad \
-skip qtlocation \
-skip qtmacextras \
-skip qtnetworkauth \
-skip qtpurchasing \
-skip qtremoteobjects \
-skip qtscript \
-skip qtscxml \
-skip qtsensors \
-skip qtspeech \
-skip qtsvg \
-skip qttools \
-skip qttranslations \
-skip qtwayland \
-skip qtwebengine \
-skip qtwebview \
-skip qtwinextras \
-skip qtx11extras \
-skip qtxmlpatterns \
-make libs \
-make examples \
-nomake tools -nomake tests \
-gui \
-widgets \
-dbus-runtime \
--glib=no \
--iconv=no \
--pcre=qt \
--zlib=qt \
-no-openssl \
--freetype=qt \
--harfbuzz=qt \
-no-opengl \
-linuxfb \
--xcb=no \
-tslib \
--libpng=qt \
--libjpeg=qt \
--sqlite=qt \
-plugin-sql-sqlite \
-I/home/xxpcb/myTest/imx6ull/otherlib/tslib-2/tslib/include \
-L/home/xxpcb/myTest/imx6ull/otherlib/tslib-2/tslib/lib \
-recheck-all

Note that three paths are your own configurations:

1 /home/xxpcb/myTest/imx6ull/otherlib/qt/qt-everywhere-src-5.12.9/arm-qt is the compilation output path.

2 /home/xxpcb/myTest/imx6ull/otherlib/tslib-2/tslib/include is the path to the tslib header files.

3 /home/xxpcb/myTest/imx6ull/otherlib/tslib-2/tslib/lib is the path to the tslib related library files.

Other parameter meanings:

-opensource: Build the open-source version of Qt

-release: Use the release version of Qt
-xplatform linux-arm-gnueabi-g++: Specify the compiler
-skip qt3d: Skip Qt’s 3D module
-make libs: Compile the libraries needed
-make examples: Compile the example codes of Qt
-nomake tools: Do not generate Qt tools
-no-openssl: Do not use OpenSSL

2.4 Compilation

Before configuration, you need to install g++

sudo apt-get install g++

Grant executable permissions to the script, then execute autoconfigure.sh

chmod +x autoconfigure.sh
./autoconfigure.sh

After running:

You can then execute make to start the compilation.

The compilation takes about ten to several dozen minutes.

After compilation, execute make install to install, and you will see the contents in the arm-qt folder:

Package the qrm-qt folder into arm-qt.tar.bz2 file for later use when porting to the development board:

tar -jcf arm-qt.tar.bz2 arm-qt

2.5 Compilation Errors

You may encounter compilation errors during make

Situation 1: I encountered the following:

This situation is because my Ubuntu virtual machine ran out of space. The solution is to expand the virtual machine, see: VirtualBox Ubuntu Expansion Record for specific operations.

Situation 2: Compilation error when compiling the latest version of Qt source code

Compilation error when using the latest version 5.15.2 of Qt, a solution has not yet been found, so I used version 5.12.9 of Qt.

3 Configuring Qt Environment on Development Board

3.1 Copying tslib and Qt Compilation Files

Copy the previously packaged arm-tslib.tar.bz2 and arm-qt.tar.bz2 compressed packages to the board, you can first copy to the nfs network location, then extract to the /usr/lib directory, and delete the useless compressed packages after extraction.

Here are the steps for arm-qt:

cp arm-qt.tar.bz2 ~/myTest/nfs/rootfs/usr/lib
cd ~/myTest/nfs/rootfs/usr/lib/
tar xf arm-qt.tar.bz2
rm arm-qt.tar.bz2

The copying and extraction process for arm-tslib is similar.

3.2 Setting Environment Variables on the Development Board

Edit /etc/profile, write the following content:

export TSLIB_ROOT=/usr/lib/arm-tslib 
export TSLIB_CONSOLEDEVICE=none 
export TSLIB_FBDEVICE=/dev/fb0 
export TSLIB_TSDEVICE=/dev/input/event1 
export TSLIB_CONFFILE=$TSLIB_ROOT/etc/ts.conf 
export TSLIB_PLUGINDIR=$TSLIB_ROOT/lib/ts 
export TSLIB_CALIBFILE=/etc/pointercal 
export  LD_PRELOAD=$TSLIB_ROOT/lib/libts.so

export QT_ROOT=/usr/lib/arm-qt 
export QT_QPA_GENERIC_PLUGINS=tslib:/dev/input/event1 
export QT_QPA_FONTDIR=/usr/share/fonts 
export QT_QPA_PLATFORM_PLUGIN_PATH=$QT_ROOT/plugins 
export QT_QPA_PLATFORM=linuxfb:tty=/dev/fb0 
export QT_PLUGIN_PATH=$QT_ROOT/plugins 
export LD_LIBRARY_PATH=$QT_ROOT/lib:$QT_ROOT/plugins/platforms 
export QML2_IMPORT_PATH=$QT_ROOT/qml 
export QT_QPA_FB_TSLIB=1

Then make this configuration take effect immediately:

source /etc/profile

4 Qt Running Test

In the compiled Qt files, there are some examples that come with Qt, you can run these examples on the board to see if the Qt program can run normally.

This is how to run one of the programs:

/usr/lib/arm-qt/examples/widgets/animation/animatedtiles/animatedtiles