oD1Y | Embedded Linux using Yocto |
Objectives
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- Good C programming skills (see our oL2 - C Language for Embedded MCUs course)
- Preferably knowledge of Linux user programming (see our oD0 - Linux User Mode Programming course)
- You may be interested also by the Yocto Expert course
- Theoretical course
- PDF course material (in English).
- Course dispensed using the Teams video-conferencing system.
- The trainer answers 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.
- Code examples, exercises and solutions
- One Online Linux PC per trainee for the practical activities.
- The trainer has access to trainees' Online PCs for technical and pedagogical assistance.
- Eclipse environment and GCC compiler.
- QEMU Emulated board or physical board connected to the online PC (depending on the course).
- Some Labs may be completed between sessions and are checked by the trainer on the next session.
- Downloadable preconfigured virtual machine for post-course practical activities
- At the start of each session the trainer will interact with the trainees to ensure the course fits their expectations and correct if needed
- 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
- Any embedded systems engineer or technician with the above prerequisites.
- The prerequisites indicated above are assessed before the training by the technical supervision of the traineein his company, or by the trainee himself in the exceptional case of an individual trainee.
- Trainee progress is assessed in two different ways, depending on the course:
- For courses lending themselves to practical exercises, the results of the exercises are checked by the trainer while, if necessary, helping trainees to carry them out by providing additional details.
- Quizzes are offered at the end of sections that do not include practical exercises to verifythat the trainees have assimilated the points presented
- At the end of the training, each trainee receives a certificate attesting that they have successfully completed the course.
- In the event of a problem, discovered during the course, due to a lack of prerequisites by the trainee a different or additional training is offered to them, generally to reinforce their prerequisites,in agreement with their company manager if applicable.
Course Outline
- Linux
- History
- Version management
- Linux architecture and modularity
- Linux system components
- The various licenses used by Linux (GPL, LGPL, etc)
- Pre-compiled toolchains
- Toolchain generation tools
- Crosstool-ng
- Buildroot
- Manual toolchain compilation
Exercise: | Creating a toolchain with crosstool-ng |
- Bootloaders (UBoot, Redboot, barebox)
- C libraries (glibc, eglibc, uClibc)
- Embedded GUIs
- Busybox
- Embedded distributions
- 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 |
- 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 |
- 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 |
- 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 |
- 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 |
- Overview of Yocto
- History
- Yocto, Open Embedded and Poky
- Purpose of the Yocto project
- The main projects
- Yocto architecture
- Overview
- Recipes and classes
- Tasks
- 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 |
- 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 |
- 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) |
- 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 |
- Creating classes
- Creating new independent classes
- Inheriting from an existing class
Exercise: | Create a class to generalize the “rootfsinstall” task |
- 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 |