For every developer at home in the world of embedded systems, the Linux operating system has become a constant companion. The question of 'why' is quickly answered: the source code is freely available, the system can be configured at will, there are no licensing costs and it can be used on almost any processor architecture. Due to these characteristics, specially adapted Linux systems can be found in, among others, industrial control systems, user interfaces and infotainment systems in the automotive sector.
Depending on the context, different requirements are placed on the Linux application:
- hard or soft real-time
- fast system start
- lightweight system
- high-resolution video playback
- Use of different bus systems and interfaces
Linux can provide these versatile requirements through customisations and extensions. AUTOSAR on Linux is used, for example, for control components in vehicles. The open source project Automotive Grade Linux (AGL) is used in in-vehicle infotainment. For the lightweight IoT sector, an integration for microcontrollers without Memory Management Unit (MMU) in the mainline kernel is available.
Choosing the right Linux distribution
We differentiate between the procedure for "prototypes without special requirements" and the procedure for "series proximity with special requirements". When implementing prototypes, it can be advantageous to use a Linux distribution that requires little maintenance and detailed knowledge, but is not as lightweight and entirely adapted to the application. We rely on the Raspberry Pi platform for our "prototypes without special requirements" and use the appropriate Raspbian Linux distribution for this phase.
When it comes to further use in a productive system or if there are special requirements to the system, a multitude of different Linux distributions and components are available. The Yocto project can be used for the flexible creation of your own Linux distribution, which is exactly tailored to your needs.
The Yocto Project
Embedded industry producers such as Windriver and Mentor rely on Yocto to develop their own Linux distribution and create highly customised systems for their customers. We also use Yocto to create custom Linux distributions for our customers' production systems.
An image and a suitable SDK for the target hardware are generated via cross compiling. In the Yocto project, the integration of the BitBake tool helps the OpenEmbedded core, the Yocto specific metadata as well as the Board Support Package (BSP) to the Poky Build Tool. With the layer concept, this basic construct can be extended by applications, functions and BSPs. This makes the resulting Linux image very flexible with regard to the requirements, the later area of application and the target hardware.
The conclusion to Embedded Linux is: "You’re spoilt for choice". There are a multitude of distributions and solutions for the embedded world. The Yocto project has been strongly represented in this area for several years. Many vendors rely on this project and the building tools it contains for their Linux distributions. If an Embedded Linux is planned for use, it definitely makes sense to take a closer look at Yocto.
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