First Session
Linux overview
- Linux
- History
- Version management
- Linux architecture and modularity
- Linux system components
- The various licenses used by Linux (GPL, LGPL, etc)
Cross compiling toolchains
- Pre-compiled toolchains
- Toolchain generation tools
- Manual toolchain compilation
| Exercise: |
Creating a toolchain with crosstool-ng |
Linux tools for embedded systems
- Bootloaders (UBoot, Redboot, barebox)
- C libraries (glibc, eglibc, uClibc)
- Embedded GUIs
- Busybox
- Embedded distributions
The U-Boot bootloader
- Introduction to U-Boot
- Booting the board through U-Boot
- Booting from NOR
- Booting from NAND
- Booting from eMMC
- Multistage Boot
- U-Boot environment variables
- User-defined variables
- Predefined variables
- Variables substitution
- The U-Boot minimal shell
- U-Boot main commands
- Booting an OS
- Accessing flash chips
- Accessing file systems (NFS, FAT, EXTx, JFFS2…)
- The full U-Boot shell
- Script structure
- Control flow instructions (if, for…)
| Exercise: |
Booting the board on NFS, using pre-existing images |
Second Session
Creating the embedded Linux kernel
- Downloading stable source code
- Getting a tarball
- Using GIT
- Configuring the kernel
- Compiling the kernel and its modules
- Modules delivered in-tree
- Out-of-tree modules
- Installing the kernel and the modules
- The Linux BSP overview
- Structure
- Device Drivers
- Device Tree
| Exercise: |
Configuring and compiling a target kernel for the target board |
Creating a root file system
- Packages
- Various package build systems (autotools, CMake, …)
- Cross-compiling a package
- The all-in-one applications
- Busybox, the basic utilities
- Dropbear: encrypted communications (ssh)
- Manually building your root file system
- Device nodes, programs and libraries
- Configuration files (network, udev, …)
- Installing modules
- Looking for and installing the needed libraries
- Testing file system consistency and completeness
| Exercise: |
Configuring and compiling Busybox and Dropbear |
| Exercise: |
Creating a minimal root file system using busybox and dropbear |
The Linux Boot
- Linux kernel parameters
- The Linux startup sequence
- Various initialization systems
- busybox init
- system V init
- systemd
- Automatically starting an embedded system
| Exercise: |
Boot Linux automatically starts a user application |
Embedded file systems
- Storage interfaces
- Flash memories and Linux MTDs
- NOR flashes
- NAND flashes
- ONENAND flashes
- The various flash file system formats
- Read-only file system
- Standard Linux file systems
- Ramdisks and initrd
- Creating an initramfs
- Booting through an initramfs
- Choosing the right file system formats
- Flashing the file system
| Exercise: |
Building an initrd root file system |
Third Session
Introduction to Yocto
- Overview of Yocto
- History
- Yocto, Open Embedded and Poky
- Purpose of the Yocto project
- The main projects
- Yocto architecture
- Overview
- Recipes and classes
- Tasks
The Yocto build system
- Build system objectives
- Building deployable images
- Layers and layer priorities
- Directory layout
- Configuration files (local, machine and distribution)
- The bitbake tool
- Using Yocto
- Building a package
- Building an image (root file system + u-boot + kernel)
- Miscellaneous tools around Yocto
| Exercise: |
Building a root file system using Yocto |
| Exercise: |
Use bitbake commands to build package & images |
| Exercise: |
Building a root file system using Yocto |
| Exercise: |
Build an extensible SDK for the generated image |
| Exercise: |
Deploy the generated image |
Yocto package recipes structure
- Recipe architecture
- Tasks
- Task dependencies
- Recipe dependencies
- The bitbake language
- Standard variables and functions
- Classes and recipes
- The base Yocto classes
- Main bitbake commands
- Adding a new layer
- Layer structure
- Various kinds of layers
| Exercise: |
Adding a new layer |
Fourth Session
Writing package recipes for Yocto
- Various kind of recipes and classes
- Bare program
- Makefile-based package
- autotools-based package
- u-boot
- kernel
- Out-of-tree module
- Recipe creation strategies
- From scratch
- Using devtool
- Using recipetool
- From an existing, similar, recipe
- Debugging recipes
- Debugging recipe selection
- Debugging dependencies
- Debugging tasks
- Defining packaging
- Automatically starting a program
| Exercise: |
Writing a recipe for a local user-maintained package |
| Exercise: |
Writing and debugging a package recipe for an autotools-based package |
| Exercise: |
Starting a program at boot (systemd) |
Modifying recipes
- Customizing an existing package recipe (.bbappend)
- Recipe dependencies
- Creating and adding patches
- Creating a patch for a community-provided component
- Creating a patch for an user-maintained component
- Defining new tasks
- Task declaration
- Coding tasks
| Exercise: |
Adding patches and dependencies to a community package |
| Exercise: |
Adding a rootfsinstall task to directly copy the output of a user package in the rootfs image |
Fifth Session
Creating new kinds of recipes
- Creating classes
- Creating new independent classes
- Inheriting from an existing class
| Exercise: |
Create a class to generalize the “rootfsinstall” task |
Creating a root file system
- Building a root file system with Yocto
- Creating a custom root file system
- Writing an image recipe
- Selecting the packages to build
- Selecting the file system types
- The various kinds of images
- Inheriting and customizing images
- Customizing system configuration files (network, mount points, …)
- Users and groups management
- Package management
| Exercise: |
Writing and building an image recipe |
| Exercise: |
Add new users to the image |
| Exercise: |
Create an image with package support for OTA deployment |
| Exercise: |
Test OTA update on the generated image |
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