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ac6 >> ac6-training >> Online Training >> Linux >> Embedded Linux using Yocto Download Catalog Download as PDF Write us Printable version

oD1Y Embedded Linux using Yocto

formateur
Objectives
  • Understanding the architecture of the Linux system
  • Create and use a cross-development toolchain
  • Learn how to install Linux on your hardware
  • Explore the Linux system architecture
    • Booting Linux
    • Initializing the system
  • Install existing packages on the target
  • Learn how to install Linux on flash chips
  • Using and customizing Yocto
  • Creating Yocto-based Embedded Linux platforms
  • Using Yocto to develop components
Labs are conducted QEMU ARM-based board
We use a recent version of Kernel
We use a recent version of Yocto
Prerequisite
Course environment
  • Theoretical course
    • PDF course material (in English)
    • Course dispensed using the Teams video-conferencing system
    • The trainer to answer trainees’ questions during the training and provide technical and pedagogical assistance through the Teams video-conferencing system
  • Practical activities
    • Practical activities represent from 40% to 50% of course duration
    • One Online Linux PC per trainee for the practical activities
    • The trainer has access to trainees’ Online PCs for technical and pedagogical assistance
  • Downloadable preconfigured virtual machine for post-course practical activities
Duration
  • Total: 30 hours
  • 5 sessions, 6 hours each (excluding break time)
  • From 40% to 50% of training time is devoted to practical activities
  • Some Labs may be completed between sessions and are checked by the trainer on the next session

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
    • Crosstool-ng
    • Buildroot
  • 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
    • Block devices
    • MTD
  • Flash memories and Linux MTDs
    • NOR flashes
    • NAND flashes
    • ONENAND flashes
  • The various flash file system formats
    • JFFS2, YAFFS2, UBIFS
  • Read-only file system
    • CRAMFS, SQUASHFS
  • Standard Linux file systems
    • Ext2/3/4, FAT, NFS
  • 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
    • Yocto SDK
    • Extensible SDK
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
    • Package splitting
  • 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
    • rpm
    • opkg
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