In this five-day course, the concepts of Embedded Linux are illustrated through practical exercises combined with theory. Hands-on sessions are carried out on the host with a Yocto Project® Software Development Kit (SDK) and target hardware (e.g. i.mx6). The entire workshop is designed to bring you up to speed as quickly as possible. The philosophy, concepts, and commands necessary to use Embedded Linux effectively are described through a unique combination of theory and practice. Instead of trying to figure it all out yourself, learn from an experienced trainer and incorporate the newly acquired knowledge of Embedded Linux into your own embedded development projects.

• Basic familiarity with using a Linux system (e.g. Ubuntu) as an end user in user space
• Basic familiarity with a command-line shell
• Familiarity with embedded C concepts and programming
• The ability to develop software using C syntax
• Basic knowledge concerning embedded processors and development boards
• …and/or no fear to learn more of the above…

Managers, project managers, software-, hardware-, development-, systems engineers, testers, administrators, technicians, and other parties interested in the technology, who want to understand as quickly as possible how Embedded Linux works.

• You must be using Linux or you can have the luxury of deciding whether or not it makes sense to use it.
• Maybe you already tried to use Embedded Linux, but are not quite sure that you did everything the right way.
• You currently use a different operating system and want to figure out whether Linux might be better and/or cheaper.

Day 1

Introduction

• History of Unix/Linux | Licensing | Standards | Working with Free Software | Spelunking | Unix Philosophy

Host playground

• architecture | shell | user | su | file hierarchy standard (FHS) | daemons | static libraries/shared libraries | permissions | access control | umask | hard Links | soft Links | more permission bits | (cross) compile Framework | real/effective user id(uid) | real/effective group id(gid)

Day 2

Processes and Inter-Process Communication (IPC)

• Linux architecture | What’s an operating system? | What’s a scheduler? | Linux: scheduler(s) – priorities – scheduling classes | Process, Task, Thread | errno | fork | process termination | process states | zombies | How can you investigate processes?
• simple interprocess communication (IPC)
  • shell redirection | shelling out | tmpfiles
• advanced interprocess communication (IPC)
  • generic | pipe | signal | interrupted system call | message queue | semaphore | mutex | shared memory | socket | select | poll
• other interprocess communication methods | Interprocess communication techniques that should be avoided

Day 3

Linux Hardware Kit

• How does Linux boot on a PC and on the evaluation board? | Boot sequence | SD card partitions | See it booting

What’s needed on…

• host
  • Toolkit
    • The Yocto Project® | Install the Yocto Project® SDK
  • SD card preparation | terminal emulation
    • screen | byobu | minicom
  • servers
    • tftp | NFS
  • root file systems
• target system
  • git | u-boot
    •  scripting | fancy stuff | checkout | config | build | install | variables and commands
  • Flat device tree (fdt)
    • what is a fdt? | device tree compiler | examples
  • kernel
    • checkout | config-kconfig | build-kbuild
  • Flat device tree (fdt)
    • build | install
  • kernel modules
    • build | install

Day 4

Root File Systems

• prepare minimal rootfs | tftp server for tests
• ramdisk | mtd | jffs2 | mtdparts | cramfs | roEXT2 | rootfs comparison

Customizations

• system hangs | pseudo tty | getty | runlevel | static ip | mount nfs | ssh server

User Space Debugging

• What is a bug/debugging? | Types of bugs | Debugging strategy
• Simple tools
  • lsof | ltrace | strace | procfs | top | netstat | syslog | …
• Advanced tools
  • What’s a debugger?
  • gdb: gdb on the target system | gdb with remote debugging

JTAG Debugging (optional)

• JTAG | JTAG setup | How to debug u-boot before Relocation | other possibilities

Profiling/Tracing

• Profiling as opposed to Tracing
• Profiling/Tracing tools: strace | system timers | gprof | gcov | perf
• top and similar programs: top | powertop | powerdebug
• crash: gdb on steroids

Day 5

Real-Time

• prerequisites
  • Difference between kernel and userspace | program sections | interrupts | re-entrant code
• Real-Time Intro
  • What is Real-Time? | What is hard Real-Time?
• Real-Time Linux
  • Hypervisor | Dual kernel | Fully Preemptive Kernel
• Degrees of Real-Time behavior
  • explicit/implicit preemption points | real-time preemption patch | fully preemptive kernel | hard real-time extensions
  • (optional) patch/config/build kernel | test it on the target system
• Dual Kernel
  • RTLinux | Real-time application interface (RTAI) | Xenomai
    • Xenomai compared to RTAI | Adaptive Domain Environment for Operating Systems (ADEOS) | Xenomai architecture/SW stack/Skins
    •  (optional) patch/config/build kernel | test it on the target system
• Measurement results: non real-time kernel | preempt-rt kernel | Dual Kernel (Xenomai)
• Real-Time Myths

• ”Refresher to Embedded Linux & Intro to the Yocto Project (5 days)”
  • https://rlbl.me/intely-r-en-pdf
• ”Embedded Linux Kernel Internals and Device Drivers (5 days)”
  • https://rlbl.me/ldd-en-pdf
• ”The Yocto Project – A thorough Overview (4 days)”
  • https://rlbl.me/yocto-r-en-pdf
• ”Introduction to Embedded Linux & Real-Time, bird’s eye view of the Yocto Project (4 days)”
  • https://rlbl.me/entirety-en-pdf
• ”Introduction to Embedded Linux in Theory and Practice – a Crash Course (3 days)”
  • https://rlbl.me/elin-en-pdf
• ”(Embedded) Linux debugging (3 days)”
  • https://rlbl.me/lindeb-r-en-pdf
• ”FreeRTOS in Theory and Practice (3 days)”
  • https://rlbl.me/freertos-r-en-pdf