Toolchains

The SDK should contain a build of Qt Embedded, but also optional dependencies like directFB, glib-2.0, gstreamer-0.10, tslib and more esoteric dependencies like mysql and postgres. This allows developers to simply start developing using Qt and enables system integrator to easily recompile Qt and base libraries without tracking down extra dependencies.

OpenEmbedded provides an easy way to create a Qt Embedded SDK. In recipes/tasks/task-qte-toolchain-host.bb host tools like moc, uic, rcc, qmake will get installed and in recipes/tasks/task-qte-toolchain-target.bb the Qt4 header files and libraries will be installed.

To build the SDK, setup OpenEmbedded in the usual way by picking a DISTRO and MACHINE. Issue the below command and after the operation finished you should find a SDK in the deployment directory.

$ bitbake meta-toolchain-qte

In this example we are assuming that the target hardware is an armv5t system and the SDK targets the Angstrom Distribution. You should start by downloading the SDK and untar it to the root folder (/). Once this operation is finished you will find a new directory /usr/local/angstrom/arm/ and it contains the environment-setup to setup the QMAKESPEC and various other paths.

Untar the SDK once
$ tar -C / -xjf angstrom-armv5te-linux-gnueabi-toolchain-qte.tar.bz2

Before using it source the environment
$ . /usr/local/angstrom/arm/environment-setup

Use qmake2 to build software for the target
$ qmake2

Creating and building a simple example. We will create a simple Qt Embedded application and use qmake2 and make to cross compile.

$ . /usr/local/angstrom/arm/environment-setup
$ cd $HOME
$ mkdir qte-example
$ cd qte-example

$ echo "TEMPLATE=app
SOURCES=main.cpp
" > qte-example.pro

$ echo '#include <QApplication>
#include <QPushButton>

int main(int argc, char** argv) {
    QApplication app(argc, argv);

    QPushButton btn("Hello World");
    btn.show();
    btn.showMaximized();

    return app.exec();
}
' > main.cpp

$ qmake2
$ make