The Yocto Project® is a collaborative Open Source project that provides templates, tools and methods to help create custom Linux-based systems for embedded products, regardless of the hardware architecture. It was founded in 2010 as a collaboration among hardware manufacturers, open-source operating systems vendors, and electronics companies to help standardize embedded Linux development. This webinar will: Present an introduction to the Yocto framework, starting with an overview of Yocto including its advantages and limitations as compared to other approaches for building an embedded Linux image. Describe the major components of Yocto, including what it provides and the tools and components it offers to create embedded Linux systems. An example will be given of creating a Yocto image for the Beaglebone, a low-cost ARM development board. The steps will include building the OS image, creating an SDK for cross-compilation, and deploying the image to the board. Introduce key tools including bitbake and its related configuration files as well as the graphical "toaster" tool. The development platform used will be a Linux-based desktop system. Provide suggestions on how to get started using Yocto and a list of references to more information including web sites and published books. Attendees will gain a good overall understanding of what Yocto provides, the advantages it offers, and the basic process for using it to create an embedded Linux distribution. No previous experience with Yocto will be assumed, although a general understanding of embedded systems development is useful.

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An Introduction to the Yocto
Embedded Framework
Jeff Tranter <jtranter@ics.com>
Integrated Computer Solutions, Inc.

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Agenda
• What is Yocto?
• Why is it Needed?
• What Yocto Provides
• Benefts/Advantages
• Limitations/Disadvantages
• Yocto Versions
• Other Framework Options
• Yocto Architecture
• Major Components
• Using Yocto - Basic Steps
• OpenEmbeddedBuild System
• Bitbake Metadata
• Example - Emulator
• Example - Beaglebone Black
• Building an SDK
• Packaging
• Toaster GUI
• Qt Yocto Support
• Doing More
• Tips For Getting Started
• References
• Summary
• Q&A

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What is Yocto?
• Project to provide templates, tools and methods to create custom Linux-
based embedded systems
• Founded in 2010
• Open Source, managed by The Linux Foundation
• Vendor and platform neutral
• Collaborative effort among participants
• Members/participants/sponsors include Intel, AMD, Broadcom, TI,
Freescale, LG Electronics, Huawei, Mentor Graphics, Dell, The Qt Company

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Why Is It Needed?
• Embedded development is signifcantly harder than native/desktop
development
• Cross-compilation
• Wide scope: boot loader, kernel, BSP/device drivers, packaging format,
utilities, applications, SDK
• Large, time consuming to build
• Desire for repeatability, automation
• Licensing issues
• Regular need for security and other updates

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What Yocto Provides
• Framework for creating embedded Linux systems
• Targets supported: ARM, PPC, MIPS, x86, x86-64
• Hosted on common Linux x86 desktop platforms (CentOS, Fedora,
openSUSE, Ubuntu)
• OpenEmbedded build system with bitbake build engine
• IDE
• Optional graphical interface to build system

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Benefits/Advantages
• Reduced development effort/time
• Improved quality
• Automation
• Stability
• Repeatability

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Limitations/Disadvantages
• Embedded Linux targets only
• Development tools run on desktop Linux only (or in a Linux vm hosted on
e.g. Windows or MacOS)
• Doesn't dictate a specifc Linux distribution (but offers Poky as a reference
distribution)
• Large, complex, can have steep learning curve

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Yocto Versions/Code Names

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Other Embedded Frameworks
• Baserock
• Buildroot
• Crosstool/CrosstoolNG
• Embedded Debian/Fedora/Gentoo/SUSE/Ubuntu

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Yocto Architecture

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Major Components
• bitbake
• Poky Linux distribution
• Emulator
• Toaster GUI
• SDK
• Eclipse IDE plugin
• Build Appliance

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Using Yocto - Basic Steps
1. Set up tools on a Linux host machine.
2. Confgure bitbake for embedded hardware.
3. Build software components, bootloader, root fs, image.
4. Write boot image and fle system.
5. Set up SDK.
6. Develop and iterate.

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Bitbake Build System
Steps:
• fetch
• extract
• patch
• confgure
• build
• install
• package

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Bitbake Metadata

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Example - Building For Emulator
$ sudo apt-get install gawk wget git-core diffstat unzip
texinfo gcc-multilib build-essential chrpath socat libsdl1.2-
dev xterm

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Example - Building For Emulator
$ mkdir yocto
$ cd yocto
$ wget http://downloads.yoctoproject.org/releases/yocto/yocto-
2.4/poky-rocko-18.0.1.tar.bz2
$ tar xvf poky-rocko-18.0.1.tar.bz2
$ cd poky-rocko-18.0.1
$ source oe-init-build-env
$ edit conf/local.conf
$ bitbake core-image-sato
$ runqemu qemuarm

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Example - Building For Emulator

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Example - Building For Emulator

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Example - Building For Emulator

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Example - Building For Emulator

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Example - Building for Beaglebone Black

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Example - Building for Beaglebone Black
Device Boot Start End Blocks Id System
/dev/mmcblk0p1 * 2048 146570 72261+ c W95 FAT32(LBA)
/dev/mmcblk0p2 146571 8535178 4194304 83 Linux
$ sudo mkfs.vfat -F 16 -n "boot" /dev/mmcblk0p1
$ sudo mke2fs -j -L "root" /dev/mmcblk0p2

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Example - Building for Beaglebone Black
$ cp tmp/deploy/images/beaglebone/MLO-beaglebone /media/
$LOGNAME/boot/MLO
$ cp tmp/deploy/images/beaglebone/u-boot-beaglebone.img /media/
$LOGNAME/boot/u-boot.img
$ sudo tar x -C /media/$LOGNAME/root -f
tmp/deploy/images/beaglebone/core-image-sato-beaglebone.tar.bz2

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Building an SDK
$ bitbake core-image-sato -c populate_sdk
Output is:
tmp/deploy/sdk/poky-glibc-x86_64-core-image-sato-armv5e-
toolchain-2.4.sh

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Building an SDK
$ ~/yocto/poky-rocko-18.0.1/build/tmp/deploy/sdk/poky-glibc-x86_64-
core-image-sato-armv5e-toolchain-2.4.1.sh
Poky (Yocto Project Reference Distro) SDK installer version 2.4.1
===============================================================
Enter target directory for SDK (default: /opt/poky/2.4.1):
You are about to install the SDK to "/opt/poky/2.4.1". Proceed[Y/n]?
Extracting SDK............................................done
Setting it up...done
SDK has been successfully set up and is ready to be used.
Each time you wish to use the SDK in a new shell session, you need to
source the environment setup script e.g.
$ . /opt/poky/2.4.1/environment-setup-armv5e-poky-linux-gnueabi

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Building an SDK
$ . /opt/poky/2.4.1/environment-setup-armv5e-poky-linux-gnueabi
$ echo $CXX
arm-poky-linux-gnueabi-g++ -march=armv5e -marm –
sysroot=/opt/poky/2.4.1/sysroots/armv5e-poky-linux-gnueabi
$ $CXX helloworld.cpp
$ file a.out
a.out: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV),
dynamically linked, interpreter /lib/ld-linux.so.3, for GNU/Linux
3.2.0

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Packaging
• Not required, but often useful even for embedded systems.
• Yocto doesn't impose a packaging format.
• Common package formats include:
• rpm
• deb/dpkg
• ipkg
• opkg

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Toaster GUI

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Yocto Qt Support
Yocto Qt 5 recipes:
• https://github.com/meta-qt5/meta-qt5
Qt for Device Creation (boot2qt):
• http://code.qt.io/cgit/yocto/meta-boot2qt.git/
• http://code.qt.io/cgit/yocto/meta-qt5.git/

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Example – Building boot2qt for Raspberry Pi
$ git clone git://code.qt.io/yocto/meta-boot2qt.git
$ cd meta-boot2qt
$ ./b2qt-init-build-env init --device raspberrypi3
$ export MACHINE=raspberrypi3
$ . setup-environment.sh
$ bitbake b2qt-embedded-qt5-image
Creates: tmp/deploy/images/raspberrypi3/b2qt-embedded-qt5-image-
raspberrypi3.img
$ bitbake meta-toolchain-b2qt-embedded-qt5-sdk
Creates: tmp/deploy/sdk/b2qt-x86_64-meta-toolchain-b2qt-embedded-qt5-sdk-
raspberrypi3.sh
See http://doc.qt.io/QtForDeviceCreation/qtee-custom-embedded-linux-image.html

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More About Bitbake
• Python based language for confguration fles.
• Supports variables, include fles, functions, inheritance.
• Uses scripts called "recipes".
• Many command line options.
• Confguration fles in build/conf
• Understands dependencies.
• Multithreaded, runs a server process in the background.

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Doing More - Writing Recipes
• Needed to build your own components with bitbake
• Shell or Python scripts (.bb fles)
• Standardized format

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Doing More - Kernel Recipes
• Recipes to confgure, patch, and build the Linux kernel
• More complex

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Doing More - BSPs
• BSP = Board Support Package.
• Adaptations for specifc hardware.
• Hardware vendor, OS vendor, or third party may provide this.

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Doing More - Eclipse Integration

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Doing More - Licensing and Compliance

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Tips For Getting Started

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References
1. Embedded Linux Systems with the Yocto Project, Rudolf Streif
2. https://www.yoctoproject.org/
3. https://github.com/meta-qt5/meta-qt5
4. http://code.qt.io/cgit/yocto/meta-boot2qt.git/
5. http://code.qt.io/cgit/yocto/meta-qt5.git/
6. http://www.ics.com/blog/yocto-quick-start

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Summary

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Questions?

41. © Integrated Computer Solutions, Inc. All Rights Reserved
An Introduction to the Yocto
Embedded Framework
Jeff Tranter <jtranter@ics.com>
Integrated Computer Solutions, Inc.