The process that we need to set up on our host system depends on the distribution we run on it. Poky has a set of supported Linux distributions, and if we are new to embedded Linux development, it is advisable to use one of the supported Linux distributions to avoid wasting time debugging build issues related to the host system support.

If you use the current release of one of following distributions, you should be good:

• Ubuntu
• Fedora
• CentOS
• Debian
• openSUSE

To confirm if your version is supported, it is advisable to check the official documentation online at http://www.yoctoproject.org/docs/current/mega-manual/mega-manual.html#detailed-supported-distros.

If your preferred distribution is not on the preceding list, it doesn't mean it is not possible to use Poky on it. However, it is unknown whether it will work, and we may get unexpected results...

After we install the needed packages into our development host system, we need to get the Poky source code that can be downloaded with Git by using the following command:

$ git clone git://git.yoctoproject.org/poky -b rocko

After the download process is complete, we should have the following contents inside the poky directory:

Inside the poky directory, there is a script named oe-init-build-env, which should be used to set up the building environment. The script must be run as shown:

$ source oe-init-build-env [build-directory]

Here, build-directory is an optional parameter for the name of the directory where the environment is set; in case it is not given, it defaults to build. The build-directory is the place where we perform the builds.

It is very convenient to use different build directories. We can work on distinct projects in parallel or different experimental setups without affecting our other builds.

When we initialize a build environment, it creates a file called build/conf/local.conf, which is a powerful tool that can configure almost every aspect of the build process. We can set the machine we are building for, the toolchain host architecture to be used for a custom cross-toolchain, optimize options for maximum build time reduction, and so on. The comments inside the build/conf/local.conf file are a very good documentation and reference of possible variables, and their defaults. The minimal set of variables that we probably want to change from the default is the following:

MACHINE ??= "qemux86"

The MACHINE variable is where we determine the target machine we wish to build for. At the time of writing this book, Poky supports the following machines in its reference BSP:

• beaglebone: This is BeagleBone, that is the reference platform for...

Poky provides several predesigned image recipes that we can use to build our own binary image. We can check the list of available images by running the following command from the poky directory:

$ ls meta*/recipes*/images/*.bb

All the recipes provide images which are a set of unpacked and configured packages, generating a filesystem that we can use on a hardware or one of the supported QEMU machines.

Next, we can see the list of most commonly used images:

• core-image-minimal: This is a small image allowing a device to boot, and it is very useful for kernel and boot loader tests and development.
• core-image-base: This is a console-only image that fully supports the target device hardware.
• core-image-weston: This is an image that provides the Wayland protocol libraries and the reference Weston compositor.
• core-image-x11: This is a very basic X11 image with...