Getting the Cross Compilation Toolchain


The app creation process of AsteroidOS needs a Software Development Kit generated by OpenEmbedded. You can either grab a prebuilt SDK for the nightlies here and install it on your system or you can build it yourself as follows:

Building the Cross Compilation Toolchain


Alternatively you can also build the toolchain from source. If you’ve already got an OpenEmbedded build directory via the Building AsteroidOS page, cd to that directory. Else, create one with:

Without Docker

git clone https://github.com/AsteroidOS/asteroid
cd asteroid/

Then, build the cross compilation toolchain with:

source ./prepare-build.sh dory
bitbake meta-toolchain-qt5

Docker

Assuming you already prepared a docker build environment like in: Building AsteroidOS.

sudo docker rm -f asteroidos-toolchain ; sudo docker run --name asteroidos-toolchain -it -v /etc/passwd:/etc/passwd:ro -u "$(id -u):$(id -g)" -v "$HOME/.gitconfig:/$HOME/.gitconfig:ro" -v "$(pwd):/asteroid" asteroidos-toolchain bash -c "source ./prepare-build.sh dory && bitbake meta-toolchain-qt5"

Install the SDK


If you downloaded a prebuilt SDK, run the downloaded script. If you followed the previous steps, this will have generated the same installation script in tmp-glibc/deploy/sdk/, you can run it as follows:

./tmp-glibc/deploy/sdk/oecore-x86_64-armv7vehf-neon-toolchain-nodistro.0.sh

This script will install the cross-compiler and ARM libraries in /usr/local/oecore-x86_64 by default, along with a script that needs to be sourced before every build. If you want to build a simple project via the terminal, this can be done like that:

source /usr/local/oecore-x86_64/environment-setup-armv7vehf-neon-oe-linux-gnueabi
qmake
make

Configure QtCreator for cross compilation


Before running QtCreator you must run the previously mentioned script:

source /usr/local/oecore-x86_64/environment-setup-armv7vehf-neon-oe-linux-gnueabi
qtcreator

This can be done automatically by prepending source /usr/local/oecore-x86_64/environment-setup-armv7vehf-neon-oe-linux-gnueabi before #!/bin/sh in /usr/bin/qtcreator.sh

Now that you are in QtCreator go to ‘Tools->Options->Devices

  • Add a new Generic Linux Device.
  • Name it "AsteroidOS Watch".
  • Choose 192.168.2.15 as IP address.
  • Use ceres as user.
  • Choose Password authentication and leave the password field empty.

Under the 'Kits'

  • In the Compilers tab add the following GCC (C++): /usr/local/oecore-x86_64/sysroots/x86_64-oesdk-linux/usr/bin/arm-oe-linux-gnueabi/arm-oe-linux-gnueabi-g++ and GCC (C): /usr/local/oecore-x86_64/sysroots/x86_64-oesdk-linux/usr/bin/arm-oe-linux-gnueabi/arm-oe-linux-gnueabi-gcc
  • In the Debuggers tab add the following gdb: /usr/local/oecore-x86_64/sysroots/x86_64-oesdk-linux/usr/bin/arm-oe-linux-gnueabi/arm-oe-linux-gnueabi-gdb
  • In the Qt Versions tab add the following qmake: /usr/local/oecore-x86_64/sysroots/x86_64-oesdk-linux/usr/bin/qmake
  • In the Kits tab add a kit with the previously defined device, Qt5 version and compilers, set the sysroot to /usr/local/oecore-x86_64/sysroots/armv7vehf-neon-oe-linux-gnueabi/ and let the other variables empty.

First app


Asteroid-Stopwatch can act as a cool QML demo app to make your first steps into AsteroidOS development easier. You can clone it, build it, install it and then modify it to follow your needs:

git clone https://github.com/AsteroidOS/asteroid-stopwatch
cd asteroid-stopwatch/
./i18n/generate-desktop.sh . asteroid-stopwatch.desktop
source /usr/local/oecore-x86_64/environment-setup-armv7vehf-neon-oe-linux-gnueabi
qtcreator asteroid-stopwatch.pro

Try to build and deploy the app. If it wasn’t already installed, a new icon should have already appeared on asteroid-launcher.

You can start by modifying occurrences of “asteroid-stopwatch” to your app’s name. Then you can change the *.desktop file which describes the icon on the apps launcher. Then modify main.qml to describe your UI. To get started with QML development you can read the official tutorial.

Tips and tricks


If you want to start your app from the command line, open a shell with SSH, connect to ceres and use invoker:

invoker --type=qtcomponents-qt5 /usr/bin/asteroid-stopwatch

TODO: Document the integration of this invoker command as a run step in the Qt Creator configuration.

If you want to disable screen locking for easier development you can enable the demo mode of mce as root with:

mcetool -D on