Introduction to Embedded Linux and Yocto

Course Objectives

After a quick introduction to Embedded Linux (2 days) to provide an understanding of the essentials to utilize the Yocto Project (3 days). After the introduction we’ll see how a BSP/framework maintainer would use the Yocto Project as well as developers who might not even want/need to know they are using it.

Description

This five day training combines theory with hands-on exercises in order to introduce Embedded Linux and the Yocto Project.
It answers frequently asked questions like:

What is GNU/Linux?
Why use upstream?
Where to get u-boot/the kernel from? How to configure/build/install it?
How does interprocess communication work and what to use/avoid?
Is it really necessary to use another version of the tool-chain/libraries/packages for each and every GNU/Linux project and on top of that to follow a different work-flow each time?
Can you ensure that the development environment is identical for all developers/suppliers and that you can still produce identical builds like today in 10+ years from now?
Can the YP help you with Open Source license audits or do you prefer a copyright troll instead?
... and much more

Hands-on sessions are performed on target hardware (e.g. phyBOARD-Mira i.MX 6 Quad - Full Featured). After the training the students will be able to download a docker image with Ubuntu 16.x and all host dependencies pre-installed plus the examples in order to work with the course material in their own labs. Please note that the first two days Introduction to Embedded Linux might not be enough to follow the Yocto training. You might want to have a look at here. We'll have a quick look at how Embedded GNU/Linux works and configure/build the Linux kernel among other things.

Who should attend?

You already use GNU/Linux for your projects and have probably heard about the Yocto Project, but did not dare to have a closer look into it, or had difficulties using it. You don’t know whether and how your daily workflow can be accomodated in the YP and generally find the YP rather complicated. Why do we need all this since up to know everything was (supposedly) much easier? After the training you should be able to decide whether you need the YP or not. The workshop is aimed at software-, development-, system engineers, testers, administrators, engineers and other parties interested in the YP, with a minimal knowledge of Embedded GNU/Linux.

Prerequisites

Basic familiarity with using a GNU/Linux system (e.g. Ubuntu) as an end user in user space
Basic familiarity with a command line shell
Basic knowledge of user/kernel space programming with GNU/Linux
Intermediate C programming knowledge
It helps to be familiar with ”Embedded GNU/Linux Systems Architecture (5 days)" or ”Introduction to Embedded Linux in Theory and Practice - a Crash Course (3 days)” but even if you are not we'll try to get you up to speed in the first two days.
It might be helpful if you attended ”Embedded GNU/Linux Device Drivers and Kernel Internals (5 days)”, but that’s not really a prerequisite. It’s sufficient to know how to build the GNU/Linux kernel, kernel drivers in/out of tree and the fdt from the kernel side of things to follow the Yocto training which we'll try to quickly cover in the first two days.

Delivery Options

All the training material is English, but the presentation of it can be in English or in German, as you wish.

on-site - instructor driven *)
on-line - instructor driven **)

We’ll provide laptops*), boards*)**), workbooks and reference books (in English)*)**), remote access to servers and boards **), screen-sharing **), audio-bridge **). For possible training delivery options check here and/or ask here.

The work- and reference books typically stay with the students after the training.

Timetable

5 days in a row 09:00 until 17:00 with breaks (your timezone - TBD)

Trainer

check here

Course Outline

Introduction

Introduction
History

Eval board

Eval Board Introduction
Booting

How does Linux boot on a PC
How is an Embedded System different?

Booting the target

Boot Sequence
SD card partitions

Stuff needed

U-Boot
U-Boot: Fancy Stuff
U-Boot: Get/Configure/Build/Install
U-Boot: Commands
Fdt
Kernel
Kernel: Get/kbuild
Kbuild
Kernel: Configure/Build/Install
Kernel: fdt
Kernel: modules

Kernel modules

...can be
init/exit
Licensing
tainted module/kernel
EXPORT_SYMBOL()
out of tree .ko makefile
module-init-tools
put module in kernel tree
build and install
load it
parameter passing
Access TCB

Character Driver

Device Files

Intro
device types
major/minor
Architecture

Driver Kernel Interface
Device Driver

Intro
Registration
Initialization
Open Release

Misc. Char Drivers

User Space Debugging

Debugging: Simple Tools

lsof, ltrace, strace,...
procfs, top, netstat, syslog,...

Debugging: Advanced Tools

What’s a Debugger?
target gdb
gdb remote debugging

Kernel Debugging

Debugging Intro
KGDB/KDB
JTAG

Process IPC

IPC Intro

Unix/Linux architecture
What’s on OS?
What’s a scheduler?
Linux scheduler
Linux priorities
Linux scheduler(s)
Linux scheduling classes
Process/Task/Thread
errno
fork()
Process termination
Process states
Zombies
More about Processes
Watch a process

Simple IPC

shell redirection
shelling out
tempfiles

IPC Generic
IPC

Message passing vs. shared memory

Advanced IPC

Pipes
Signals
Interrupted System Calls
POSIX.4 Message Queues
Semaphores Introduction
Mutex
Semaphores
Shared Memory
Sockets
select

self-pipe trick

Other IPC mechanisms

IPC techniques to avoid

Real-Time

Prerequisites

Kernel vs. User Space
Toolchain
Program Sections
Interrupts
Reentrant Code

Real-Time Intro

Time/Utility Functions
What is Real-Time?
Determinism
What is hard real-time?

Real-Time Linux
"Degrees" of real-time behavior
Dual kernel

Xenomai
Measurement results

Real-Time Myths

Yocto Introduction

What is Yocto?
Why use the YP?
What is the YP?
Some tools under the YP umbrella

Poky
BitBake
OE-Core
Metadata

The Yocto Autobuilder

Intro

What is the Yocto Autobuilder?
Docker container (pull, launch container)

Yocto build environment without Docker/Yocto Autobuilder

The YP Workflow

Intro
Workflow

OE architecture

Configuration

User Configuration
Features

Machine Features
Distro Features
Combined Features
Image Features

Recipe Versioning

Intro
Hyphens
SCM-based
Pitfalls
Devel/Stable
Overrides

Metadata (Recipes)
Machine (BSP) Configuration
Distribution Policy

Sources
Build

Source fetching: do_fetch, do_unpack
Patching
Configure/Compile/Install
Pseudo
recipetool
Examples of Recipes

Single .c File Package
Autotooled Package
Splitting App. in Multiple Packages

Output Analysis/Packaging
Image Generation
SDK Generation

Customizing Images

Intro
local.conf
IMAGE_FEATURES
custom .bb files - inherit core-image
custom .bb files - based on core-image-minimal
custom packagegroups

BitBake

History
Syntax

Variable Expansion
Variable Assignment
Pre-/Append
Removal (Override Style Syntax)
Variable Flag Syntax
Conditional Syntax (Overrides)

Debugging

BitBake debugging
find recipes
find images
find packagegroups
BitBake Environment
BitBake logs
Re-BitBake stuff

force build/specific task
cleansstate
invalidate stamp

Devshell
Dependencies
Packages
Killall Bitbake
BitBake with ncurses wrapper
Tools/Tweaks

Cleaning

Cleaning to gain disc space
Cleaning to rebuild

Layers

Intro
bitbake-layers tool
yocto-layer tool

BSP

Intro
System Development Workflow
BSP Developer’s Guide

bsp-tool

Kernel

Intro
System Development Workflow
Kernel Development Manual

defconfig + configuration fragment
in tree kmod
out of tree kmod
fdt

Software Development Kit

Software Development Kit

Intro
Cross-Development Toolchain
Sysroot
The QEMU Emulator
Eclipse Yocto Plug-in
Performance Enhancing tools

Installing SDKs & Toolchains
Cross-Toolchains/SDKs

Intro
Building a Cross-Toolchain installer
Using the Standard SDK
Cross-Toolchain+Makefile
Cross-Toolchain+Autotools
Autotooled lib + App., recipes
Extensible SDK

Package Management

Software updates
Working with packages

IPK
creating a package feed
installing a package with opkg on the target

Licensing

Intro
Add custom license to the YP
Open Source License Compliance with the YP

Devtool

Intro
Add recipe/Build/Deploy
Create/Add layer
Finish
Modify/Update-Recipe
Build/Run
Build Image

Please fill in this form if you have further questions regarding this or any other training and do not hesitate to contact us if you have any further questions.

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Note: Alternatively, there is also a four-day Yocto training The Yocto Project - An Overview.

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