Audience

This course is ideal for software engineers who are familiar with embedded devices but need to apply that knowledge to Linux development, and to those who are familiar with Linux, but want to apply that knowledge to embedded systems

Precognition

• Essential: good knowledge of the C programming language, since this is used in the programming portions of the Course
• Desirable: either a good background in embedded devices, or a reasonable proficiency in Linux command-line tools. Delegates with neither will find the learning curve rather steep

Learning target

This intensive four-day course will teach you the techniques required to build Linux into embedded systems. During the hands-on sessions you will learn about the fundamental elements that underpin all embedded Linux projects: the toolchain, the bootloader, the Linux kernel and the root filesystem. You will create each of these elements from scratch, and discover out how to automate the process using tools such as Buildroot and the Yocto Project. In later sessions you will delve into architectural issues such as file system layout, how to split functions between user and kernel space and real-time programming. You will also find out how to debug and profile code at both the application level and within the kernel so that you will be able to identify bugs and resolve performance bottlenecks.

Content

• Embedded Linux
  • Linux as an embedded operating system
  • Working with open source licenses
• Toolchain, bootloader and kernel
  • The toolchain: choosing, installing and testing
  • The bootloader: how to load Linux into memory using U-Boot
  • The Linux kernel: customising and cross-compiling
  • Device trees: how they work and how to modify them to fit your hardware
• Root filesystem and networking
  • Directory layout
  • Important programs: init and the shell
  • Creating a basic network configuration
  • Creating user accounts
• Embedded Linux build systems
  • Buildroot
  • The Yocto Project
• Init, device manager and log daemon
  • Choices for init: Busybox, SysV, systemd
  • Examples using Busybox init and systemd
  • Device managers: populating /dev
  • Options for the system log daemon
• File systems and flash memory
  • Flash memory: NOR, NAND and eMMC
  • Choosing the right file system: JFFS2, UBIFS, EXT4 and tmpfs
  • Designing a robust in-field update mechanism
• Linux kernel programming and device drivers
  • Writing kernel code: kernel modules
  • Anatomy of a simple device driver
  • Kernel debugging: interpreting an oops message; interactive debugging using kgdb
• Developing and debugging
  • Application program interfaces: the POSIX standard
  • Calling device drivers from user space
  • Debugging applications remotely using gdbserver
• Real time
• • Linux scheduling policies
  • Kernel preemption and scheduling latencies
  • Real-time: hard or soft? Impact on kernel and applications
  • Approaching hard real-time with the PREEMPT_RT patch

Language

This course will be held in english from the linux expert Chris Simmonds.

Other informations

A printed copy of the presentations and lab notes

An essential part of the training are the lab sessions, which take approximately 50% of the time. We normally work in pairs using a modern development board such as the BeagleBone Black. Each group will also need a laptop or desktop to run the system development tools. We will provide a bootable USB memory stick with an appropriate version of Linux and cross tool-chain so there is no need to install Linux beforehand.