This manual provides reference information for the current release of the Yocto Project. The Yocto Project is an open-source collaboration project focused on embedded Linux developers.
Amongst other things, the Yocto Project uses the OpenEmbedded build system, which is based on the Poky project, to construct complete Linux images. You can find complete introductory and getting started information on the Yocto Project by reading the Yocto Project Quick Start. Finally, you can also find lots of Yocto Project information on the Yocto Project website. Using the Yocto Project : Provides an overview of the components that make up the Yocto Project followed by information about debugging images created in the Yocto Project.
A Closer Look at the Yocto Project Development Environment : Provides a more detailed look at the Yocto Project development environment within the context of development.
Technical Details : Describes fundamental Yocto Project components as well as an explanation behind how the Yocto Project uses shared state sstate cache to speed build time. Directory Structure : Describes the Source Directory created either by unpacking a released Yocto Project tarball on your host development system, or by cloning the upstream Poky Git repository. Classes : Describes the classes used in the Yocto Project. Tasks : Describes the tasks defined by the OpenEmbedded build system.
Images : Describes the standard images that the Yocto Project supports. Features : Describes mechanisms for creating distribution, machine, and image features during the build process using the OpenEmbedded build system. Entries describe the function of the variable and how to apply them.
Variable Context : Provides variable locality or context. Contributing to the Yocto Project : Provides guidance on how you can contribute back to the Yocto Project. The remainder of this section provides details on system requirements not covered in the Yocto Project Quick Start.
Currently, the Yocto Project is supported on the following distributions:. Yocto Project releases are tested against the stable Linux distributions in the following list. The Yocto Project should work on other distributions but validation is not performed against them.I recently had the opportunity of using Yocto to create an embedded Linux image for a Zynq for a project at work.
After about five or six months of learning and using Yocto, I can say two things:. One : Yocto provides a set of powerful tools that allow you to tailor Linux to meet all your embedded hardware and software needs. Two : there is a very steep learning curve to the Yocto tools, even if you're already pretty familiar with Linux and embedded systems. This isn't necessarily a shocker, right?
These two things kind of go hand in hand.
Any tool that grants you such a large degree of power in customizing Linux to meet your exact needs is going to have a lot of ins and outs. Of course, there are heaps and heaps of solid documentation describing all the various aspects of Yocto and Bitbake in the Yocto Mega Manual.
The real issue for me was that I couldn't find a tutorial that worked through all of the specific things I wanted to do with my board. This tutorial is my attempt to try to provide some very concrete examples in each of the steps you use as you go along in a Yocto build.
I call it Hacking Rapberry 4 because we're going to be going away from the easy-to-install images that are available for the board, and instead tinker around with the bootloader, device tree, kernel, and root filesystem using Yocto. If you plan on following along for the whole thing, I should warn you that I will purposely be making mistakes along the way!
In my opinion, the best way to learn the guts of embedded Linux is to make some mistakes and observe what sort of symptoms result from those mistakes. This tutorial is NOT for folks that just want to get Linux up and running with a nice GUI so they can use a video game emulator or host a media server.
For that, Raspbian or NOOBs should do the job, and it will be far easier to get things up and running that way than what I'm going to be describing.
Or maybe you just want to see what it would take to get Linux up and running with Yocto before you commit to using it for your embedded solution. Who knows? It's possible you found this page for some really cool reason I'm not even aware of. In order to follow this tutorial all the way through, you'll need the following:.
Hacking Raspberry Pi 4 with Yocto : Introduction. Intro to the Intro I recently had the opportunity of using Yocto to create an embedded Linux image for a Zynq for a project at work. After about five or six months of learning and using Yocto, I can say two things: One : Yocto provides a set of powerful tools that allow you to tailor Linux to meet all your embedded hardware and software needs.
Who Is This Tutorial For? The intended audience for this tutorial are people that either: Are just starting to use Yocto and want some examples to follow on a cheap, widely available development board, Need to create a custom image with included packages that they'll be distributing on a large number of boards, or Want to figure out how to generate a customized device tree, ramdisk root filesystem, or bootloader.
Want to gain a better understanding of what basic files are needed to get Linux up and running on a Raspberry Pi. In order to follow this tutorial all the way through, you'll need the following: A Raspberry Pi 4.
I'm using the CanaKit 4GB version shown below and available here. See this page for more information to make sure you don't buy the wrong kind! An Ethernet cable so you can connect your Raspberry Pi to your home router or directly to your host machine.
An Ubuntu OS. Yocto and supporting packages. I'll provide steps on how to obtain what you need during the tutorial. So without further ado, let's dive in.This post is about building bit Linux systems for Raspberry Pi boards using software from the Yocto Project. If you are interested in bit systems for the RPi4 see this post. Yocto is a set of tools for building a custom embedded Linux distribution.
The systems are usually targeted for a particular application like a commercial product. If you are looking to build a general purpose development system with access to pre-built packages, I suggest you stick with a more user-friendly distribution like Raspbian.
And while the Yocto system is very powerful, it does have a substantial learning curve. You may want to look at another popular, but simpler tool for building embedded systems Buildroot. Yocto uses meta-layers to define the configuration. Within each meta-layer are recipes, classes and configuration files that support the primary build tool, a python app called bitbake.
I have created a custom meta-layer for the RPi boards called meta-rpi. The systems built from this layer use the same GPU firmware, linux kernel and include the same dtb overlays as the official Raspbian systems.
It is only the userland software that differs and that is completely configurable by you. There are a some example images in meta-rpi that support the programming languages and tools that I commonly use in my own projects.
When using this repository for customer projects, I first fork and move it to another repository, usually with a different name. I recommend you do the same if you require stability. I use the meta-rpi layer for my experiments. I am using the official Yocto meta-raspberrypi layer, but have updated recipes for the Linux kernel and gpu firmware to keep them more current.
If you want a quick look at the resulting systems, you can download some pre-built images here. All systems are setup to use a serial console.
Note: There is a firewall rule that will lock out your IP for 2 minutes after 5 failed logins. The Yocto version is 3. The 4. These are sysvinit systems using eudev. The Qt version is 5. Qt GUI applications can be run fullscreen using one of the Qt embedded linux plugins like eglfs or linuxfbboth are provided.
The default is eglfs.Live Coding with Yocto Project #3: package dependencies and splitting
Raspicam the command line tool for using the Raspberry Pi camera module is installed. There is an example image that I use for a couple of Raspberry Pi music systems. For all versions of Ubuntu, you should change the default Ubuntu shell from dash to bash by running this command from a shell.
The directory layout I am describing here is my preference. All of the paths to the meta-layers are configurable. If you choose something different, adjust the following instructions accordingly. My own common meta-layer changing some upstream package defaults and adding a few custom recipes. Create a separate sub-directory for the meta-rpi repository before cloning.Welcome to the Yocto Project!
The Yocto Project is an open-source collaboration project whose focus is developers of embedded Linux systems. The BitBake and OE components are combined together to form a reference build host, historically known as Poky. If you do not have a system that runs Linux and you want to give the Yocto Project a test run, you might consider using the Yocto Project Build Appliance. The Build Appliance allows you to build and boot a custom embedded Linux image with the Yocto Project using a non-Linux development system.
See the Yocto Project Build Appliance for more information. This quick start is written so that you can quickly get a host build host set up to use the Yocto Project and then build some Linux images. Rather than go into great detail about the Yocto Project and its many capabilities, this quick start provides the minimal information you need to try out the Yocto Project using a supported Linux build host. Reading and using the quick start should result in you having a basic understanding of what the Yocto Project is and how to use some of its core components.
You will also have worked through steps to produce two images: one suitable for emulation and one that can be used on actual hardware. The examples highlight the ease with which you can use the Yocto Project to create images for multiple types of hardware.
For more detailed information on the Yocto Project, you can reference these resources:. Website: The Yocto Project Website provides the latest builds, breaking news, full development documentation, and access to a rich Yocto Project Development Community into which you can tap. While this screencast is somewhat dated, the introductory and fundamental concepts are useful for the beginner.
Provides a recent Linux kernel along with a set of system commands and libraries suitable for the embedded environment. For devices that do not have a display or where you wish to use alternative UI frameworks, these components need not be installed. Creates a focused and stable core compatible with the OpenEmbedded project with which you can easily and reliably build and develop.
Provides a layer mechanism that allows you to easily extend the system, make customizations, and keep them organized. You can use the Yocto Project to generate images for many kinds of devices. As mentioned earlier, the Yocto Project supports creation of reference images that you can boot within and emulate using QEMU.
Beyond emulation, you can use the layer mechanism to extend support to just about any platform that Linux can run on and that a toolchain can target. The following list shows what you need in order to use a Linux-based build host to use the Yocto Project to build images:.
Build Host A build host with a minimum of 50 Gbytes of free disk space that is running a supported Linux distribution i. Build Host Packages Appropriate packages installed on the build host. The Yocto Project team verifies each release against recent versions of the most popular Linux distributions that provide stable releases. In general, if you have the current release minus one of the following distributions, you should have no problems.
The OpenEmbedded build system should be able to run on any modern distribution that has the following versions for Git, tar, and Python. Python 2. If your build host does not meet any of these three listed version requirements, you can take steps to prepare the system so that you can still use the Yocto Project.
Required build host packages vary depending on your build machine and what you want to do with the Yocto Project. For example, if you want to build an image that can run on QEMU in graphical mode a minimal, basic build requirementthen the build host package requirements are different than if you want to build an image on a headless system or build out the Yocto Project documentation set.
I have a custom board running Yocto Jethro and would like to run a single u-boot command, preboot. Obviously, breaking the boot sequence with space and running it manually works.
Build custom embedded Linux distributions with the Yocto Project
How do I get it to run automatically? More specifically, where is the startup command sequence, by default? Edit: Also, I am aware I can edit the environment at runtime. However, I am trying to build this change into the image so I can distribute it. When you are in the uboot environment. Enter printenvit will list the environment variables that uboot uses. There is a variable name bootcmd.
Currently, mine contain a bunch of if else command. Similarly, add your prefer function there for boot. Here is a syntax for uboot. U-Boot allows to store commands or command sequences in a plain text file.
Using the mkimage tool you can then convert this file into a script image which can be executed using U-Boot's autoscr command. U-boot Scripting Capabilities. Typically, your U-Boot recipe will build U-Boot for a single machine, in that case, I'd normally just patch the compiled in, default, U-Boot environment to do the right thing. This is achieved by.
what is poky and yocto
Or even better use your own git tree. This would also have the additional benefit that your system might be able to boot up and to something useful, even if the environment would be totally corrupted.
I work with the Yocto Project quite a bit and a common challenge is determining why or from what recipe a file has been included on the rootfs. Ideally, a set of commands would allow linking a file back to a source ie.
Bitbake Cheat Sheet
My usual strategy is to perform searches on the meta data e. However, this is not always very effective. In many cases, filenames are not explicitly stated within a recipe.
Additionally, there are many cases where a filename is provided by multiple recipes which leads to additional work to find which recipe ultimately supplied it. There are of course many other clues available to find the answer. Regardless, this investigation is often quite laborious when it seems the build system should have enough information to make resolving the answer simple. This is exact use case for oe-pkgdata-util script and its subcommand find-path.
That script is part of openembedded-core. If you prefer a graphical presentation, the Toaster web UI will also show you this, plus dependency information. Learn more. How to find which Yocto Project recipe populates a particular file on an image root filesystem Ask Question. Asked 3 years, 2 months ago. Active 1 year, 3 months ago. Viewed 7k times. Active Oldest Votes. See this example executed in OE build environment, i.
Tomas Novotny Tomas Novotny 5 5 silver badges 8 8 bronze badges. The best way is to use oe-pkgdata-util. Sign up or log in Sign up using Google. Sign up using Facebook.
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The Overflow Blog. Featured on Meta. Feedback on Q2 Community Roadmap.To be sure you have the latest version of the manual for this release, go to the Yocto Project documentation page and select the manual from that site. Manuals from the site are more up-to-date than manuals derived from the Yocto Project released TAR files. If you located this manual through a web search, the version of the manual might not be the one you want e. You can see all Yocto Project major releases by visiting the Releases page.
To report any inaccuracies or problems with this manual, send an email to the Yocto Project discussion group at yocto yoctoproject. This manual introduces the Yocto Project by providing concepts, software overviews, best-known-methods BKMsand any other high-level introductory information suitable for a new Yocto Project user. You will learn about features and challenges of the Yocto Project, the layer model, components and tools, development methods, the Poky reference distribution, the OpenEmbedded build system workflow, and some basic Yocto terms.
The Yocto Project Development Environment : This chapter helps you get started understanding the Yocto Project development environment. You will learn about open source, development hosts, Yocto Project source repositories, workflows using Git and the Yocto Project, a Git primer, and information about licensing. You can find conceptual information about components, development, cross-toolchains, and so forth.
Step-by-step Instructions for Development Tasks: Instructional procedures reside in other manuals within the Yocto Project documentation set. For example, the Yocto Project Development Tasks Manual provides examples on how to perform various development tasks. Reference Material: This type of material resides in an appropriate reference manual. For example, system variables are documented in the Yocto Project Reference Manual.
Because this manual presents information for many different topics, supplemental information is recommended for full comprehension. If you want to build an image with no knowledge of Yocto Project as a way of quickly testing it out, see the Yocto Project Quick Build document. For a comprehensive list of links and other documentation, see the " Links and Related Documentation " section in the Yocto Project Reference Manual. The Yocto Project is an open source collaboration project that helps developers create custom Linux-based systems that are designed for embedded products regardless of the product's hardware architecture.
Yocto Project provides a flexible toolset and a development environment that allows embedded device developers across the world to collaborate through shared technologies, software stacks, configurations, and best practices used to create these tailored Linux images. Thousands of developers worldwide have discovered that Yocto Project provides advantages in both systems and applications development, archival and management benefits, and customizations used for speed, footprint, and memory utilization.
The project is a standard when it comes to delivering embedded software stacks. The project allows software customizations and build interchange for multiple hardware platforms as well as software stacks that can be maintained and scaled.