# Getting Started with the Yocto Project

This chapter provides procedures related to getting set up to use the Yocto Project. For a more front-to-end process that takes you from minimally preparing a build host through building an image, see the Yocto Project Quick Start.

## Setting Up the Development Host to Use the Yocto Project

This section provides procedures to set up your development host to use the Yocto Project. You can use the Yocto Project on a native Linux development host or you can use CROPS, which leverages Docker Containers, to prepare any Linux, Mac, or Windows development host.

Once your development host is set up to use the Yocto Project, further steps are necessary depending on what you want to accomplish. See the following references for information on how to prepare for Board Support Package (BSP) development, kernel development, and development using the Eclipse IDE:

- BSP Development: See the "Preparing Your Build Host to Work With BSP Layers" section in the Yocto Project Board Support Package (BSP) Developer's Guide.

- Kernel Development: See the "Preparing the Build Host to Work on the Kernel" section in the Yocto Project Linux Kernel Development Manual.

- Eclipse Development: See the "Developing Applications Using Eclipse" Chapter in the Yocto Project Application Development and the Extensible Software Development Kit (eSDK) manual.

### Setting Up a Native Linux Host

Follow these steps to prepare a native Linux machine as your Yocto Project development host:

1. Use a Supported Linux Distribution: You should have a reasonably current Linux-based host system. You will have the best results with a recent release of Fedora, openSUSE, Debian, Ubuntu, or CentOS as these releases are frequently tested against the Yocto Project and officially supported. For a list of the distributions under validation and their status, see the "Supported Linux Distributions" section in the Yocto Project Reference Manual and the wiki page at Distribution Support.

2. Have Enough Free Memory: You should have at least 50 Gbytes of free disk space for building images.

3. Meet Minimal Version Requirements: The OpenEmbedded build system should be able to run on any modern distribution that has the following versions for Git, tar, and Python.

   - Git 1.8.3.1 or greater

   - tar 1.27 or greater

   - Python 3.4.0 or greater.

   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. See the "Required Git, tar, and Python Versions" section in the Yocto Project Reference Manual for information.

4. Install Development Host Packages: Required development host packages vary depending on your build machine and what you want to do with the Yocto Project. Collectively, the number of required packages is large if you want to be able to cover all cases.

   For lists of required packages for all scenarios, see the "Required Packages for the Host Development System" section in the Yocto Project Reference Manual.

Once you have completed the previous steps, you are ready to continue using a given development path on your native Linux machine. If you are going to use BitBake, see the "Cloning the `poky` Repository" section. If you are going to use the Extensible SDK, see the "Using the Extensible SDK" Chapter in the Yocto Project Application Development and the Extensible Software Development Kit (eSDK) manual. If you want to work on the kernel, see the Yocto Project Linux Kernel Development Manual. If you are going to use Toaster, see the "Setting Up and Using Toaster" section in the Toaster User Manual.

### Setting Up to Use CROss PlatformS (CROPS)

With CROPS, which leverages Docker Containers, you can create a Yocto Project development environment that is operating system agnostic. You can set up a container in which you can develop using the Yocto Project on a Windows, Mac, or Linux machine.

Follow these general steps to prepare a Windows, Mac, or Linux machine as your Yocto Project development host:

1. Go to the Docker Installation Site: Docker is a software container platform that you need to install on the host development machine. To start the installation process, see the Docker Installation site.

2. Choose Your Docker Edition: Docker comes in several editions. For the Yocto Project, the stable community edition (i.e. "Docker CE Stable") is adequate. You can learn more about the Docker editions from the site.

3. Go the Install Site for Your Platform: Click the link for the Docker edition associated with your development host machine's native software. For example, if your machine is running Microsoft Windows Version 10 and you want the Docker CE Stable edition, click that link under "Supported Platforms".

4. Understand What You Need: The install page has pre-requisites your machine must meet. Be sure you read through this page and make sure your machine meets the requirements to run Docker. If your machine does not meet the requirements, the page has instructions to handle exceptions. For example, to run Docker on Windows 10, you must have the pro version of the operating system. If you have the home version, you need to install the Docker Toolbox.

   Another example is that a Windows machine needs to have Microsoft Hyper-V. If you have a legacy version of the the Microsoft operating system or for any other reason you do not have Microsoft Hyper-V, you would have to enter the BIOS and enable virtualization.

5. Install the Software: Once you have understood all the pre-requisites, you can download and install the appropriate software. Follow the instructions for your specific machine and the type of the software you need to install.

6. Optionally Orient Yourself With Dockers: If you are unfamiliar with Dockers and the container concept, you can learn more here - . You should be able to launch Docker or the Docker Toolbox and have a terminal shell on your development host.

7. Set Up the Containers to Use the Yocto Project: Go to and follow the directions for your particular development host (i.e. Linux, Mac, or Windows).

   Once you complete the setup instructions for your machine, you have the Poky, Extensible SDK, and Toaster containers available. You can click those links from the page and learn more about using each of those containers.

Once you have a container set up, everything is in place to develop just as if you were running on a native Linux machine. If you are going to use the Poky container, see the "Cloning the `poky` Repository" section. If you are going to use the Extensible SDK container, see the "Using the Extensible SDK" Chapter in the Yocto Project Application Development and the Extensible Software Development Kit (eSDK) manual. If you are going to use the Toaster container, see the "Setting Up and Using Toaster" section in the Toaster User Manual.

## Working With Yocto Project Source Files

This section contains procedures related to locating and securing Yocto Project files. You establish and use these local files to work on projects.

### Notes

- For concepts and introductory information about Git as it is used in the Yocto Project, see the "Git" section in the Yocto Project Reference Manual.

- For concepts on Yocto Project source repositories, see the "Yocto Project Source Repositories" section in the Yocto Project Reference Manual."

### Accessing Source Repositories

Yocto Project maintains upstream Git Source Repositories that you can examine and access using a browser-based UI:

1. Access Repositories: Open a browser and go to to access the GUI-based interface into the Yocto Project source repositories.

2. Select a Repository: Click on any repository in which you are interested (e.g. `poky`).

3. Find the URL Used to Clone the Repository: At the bottom of the page, note the URL used to clone that repository (e.g. `&YOCTO_GIT_URL;/poky`).

4. Examine Change History of the Repository: At the top of the page, click on any branch in which you might be interested (e.g. `&DISTRO_NAME_NO_CAP;`). You can then view the commit log or tree view for that development branch.

### Accessing Index of Releases

Yocto Project maintains an Index of Releases area that contains related files that contribute to the Yocto Project. Rather than Git repositories, these files represent snapshot tarballs.

#### Tip

The recommended method for accessing Yocto Project components is to use Git to clone a repository and work from within that local repository. The procedure in this section exists should you desire a tarball snapshot of any given component.

1. Access the Index of Releases: Open a browser and go to to access the Index of Releases. The list represents released components (e.g. `eclipse-plugin`, `sato`, and so on).

   The `yocto` directory contains the full array of released Poky tarballs. The `poky` directory in the Index of Releases was historically used for very early releases and exists for retroactive completeness only.

2. Select a Component: Click on any released component in which you are interested (e.g. `yocto`).

3. Find the Tarball: Drill down to find the associated tarball. For example, click on `yocto-&DISTRO;` to view files associated with the Yocto Project &DISTRO; release (e.g. `poky-&DISTRO_NAME_NO_CAP;-&POKYVERSION;.tar.bz2`, which is the released Poky tarball).

4. Download the Tarball: Click a tarball to download and save a snapshot of a given component.

### Using the Downloads Page

The Yocto Project Website uses a "Downloads" area from which you can locate and download tarballs of any Yocto Project release. Rather than Git repositories, these files represent snapshot tarballs.

#### Tip

The recommended method for accessing Yocto Project components is to use Git to clone a repository and work from within that local repository. The procedure in this section exists should you desire a tarball snapshot of any given component.

1. Go to the Yocto Project Website: Open The Yocto Project Website in your browser.

2. Get to the Downloads Area: Click the "Downloads" tab.

3. Select the Type of Files: Click the type of files you want (i.e "Build System", "Tools", or "Board Support Packages (BSPs)".

4. Locate and Download the Tarball: From the list of releases, locate the appropriate download link and download the files.

### Cloning the `poky` Repository

To use the Yocto Project, you need a release of the Yocto Project locally installed on your development system. The locally installed set of files is referred to as the Source Directory in the Yocto Project documentation.

You create your Source Directory by using Git to clone a local copy of the upstream `poky` repository.

#### Tip

The preferred method of getting the Yocto Project Source Directory set up is to clone the repository. Working from a copy of the upstream repository allows you to contribute back into the Yocto Project or simply work with the latest software on a development branch. Because Git maintains and creates an upstream repository with a complete history of changes and you are working with a local clone of that repository, you have access to all the Yocto Project development branches and tag names used in the upstream repository.

Follow these steps to create a local version of the upstream `poky` Git repository.

1. Set Your Directory: Be in the directory where you want to create your local copy of poky.

2. Clone the Repository: The following command clones the repository and uses the default name "poky" for your local repository:

            $ git clone git://git.yoctoproject.org/poky
            Cloning into 'poky'...
            remote: Counting objects: 367178, done.
            remote: Compressing objects: 100% (88161/88161), done.
            remote: Total 367178 (delta 272761), reused 366942 (delta 272525)
            Receiving objects: 100% (367178/367178), 133.26 MiB | 6.40 MiB/s, done.
            Resolving deltas: 100% (272761/272761), done.
            Checking connectivity... done.

   Unless you specify a specific development branch or tag name, Git clones the "master" branch, which results in a snapshot of the latest development changes for "master". For information on how to check out a specific development branch or on how to check out a local branch based on a tag name, see the "Checking Out By Branch in Poky" and Checking Out By Tag in Poky", respectively.

   Once the repository is created, you can change to that directory and check its status. Here, the single "master" branch exists on your system and by default, it is checked out:

            $ cd ~/poky
            $ git status
            On branch master
            Your branch is up-to-date with 'origin/master'.
            nothing to commit, working directory clean
            $ git branch
            * master

   Your local repository of poky is identical to the upstream poky repository at the time from which it was cloned.

### Checking Out by Branch in Poky

When you clone the upstream poky repository, you have access to all its development branches. Each development branch in a repository is unique as it forks off the "master" branch. To see and use the files of a particular development branch locally, you need to know the branch name and then specifically check out that development branch.

Checking out an active development branch by branch name gives you a snapshot of that particular branch at the time you check it out. Further development on top of the branch that occurs after check it out can occur.

1. Switch to the Poky Directory: If you have a local poky Git repository, switch to that directory. If you do not have the local copy of poky, see the "Cloning the `poky` Repository" section.

2. Determine Existing Branch Names:

            $ git branch -a
            * master
              remotes/origin/1.1_M1
              remotes/origin/1.1_M2
              remotes/origin/1.1_M3
              remotes/origin/1.1_M4
              remotes/origin/1.2_M1
              remotes/origin/1.2_M2
              remotes/origin/1.2_M3
                  .
                  .
                  .
              remotes/origin/master-next
              remotes/origin/master-next2
              remotes/origin/morty
              remotes/origin/pinky
              remotes/origin/purple
              remotes/origin/pyro
              remotes/origin/rocko

3. Checkout the Branch: Checkout the development branch in which you want to work. For example, to access the files for the Yocto Project &DISTRO; Release (&DISTRO_NAME;), use the following command:

            $ git checkout -b &DISTRO_NAME_NO_CAP; origin/&DISTRO_NAME_NO_CAP;
            Branch &DISTRO_NAME_NO_CAP; set up to track remote branch &DISTRO_NAME_NO_CAP; from origin.
            Switched to a new branch '&DISTRO_NAME_NO_CAP;'

   The previous command checks out the "&DISTRO_NAME_NO_CAP;" development branch and reports that the branch is tracking the upstream "origin/&DISTRO_NAME_NO_CAP;" branch.

   The following command displays the branches that are now part of your local poky repository. The asterisk character indicates the branch that is currently checked out for work:

            $ git branch
              master
            * &DISTRO_NAME_NO_CAP;

### Checking Out by Tag in Poky

Similar to branches, the upstream repository uses tags to mark specific commits associated with significant points in a development branch (i.e. a release point or stage of a release). You might want to set up a local branch based on one of those points in the repository. The process is similar to checking out by branch name except you use tag names.

Checking out a branch based on a tag gives you a stable set of files not affected by development on the branch above the tag.

1. Switch to the Poky Directory: If you have a local poky Git repository, switch to that directory. If you do not have the local copy of poky, see the "Cloning the `poky` Repository" section.

2. Fetch the Tag Names: To checkout the branch based on a tag name, you need to fetch the upstream tags into your local repository:

            $ git fetch --tags
            $

3. List the Tag Names: You can list the tag names now:

            $ git tag
            1.1_M1.final
            1.1_M1.rc1
            1.1_M1.rc2
            1.1_M2.final
            1.1_M2.rc1
               .
               .
               .
            yocto-2.2
            yocto-2.2.1
            yocto-2.3
            yocto-2.3.1
            yocto-2.4
            yocto_1.5_M5.rc8

4. Checkout the Branch:

            $ git checkout tags/&DISTRO; -b my_yocto_&DISTRO;
            Switched to a new branch 'my_yocto_&DISTRO;'
            $ git branch
              master
            * my_yocto_&DISTRO;

   The previous command creates and checks out a local branch named "my_yocto_&DISTRO;", which is based on the commit in the upstream poky repository that has the same tag. In this example, the files you have available locally as a result of the `checkout` command are a snapshot of the "&DISTRO_NAME_NO_CAP;" development branch at the point where Yocto Project &DISTRO; was released.

## Performing a Simple Build

Several methods exist that allow you to build an image within the Yocto Project. This procedure shows how to build an image using BitBake from a Linux host.

### Notes

- For information on how to build an image using Toaster, see the Yocto Project Toaster Manual.

- For information on how to use `devtool` to build images, see the "Using `devtool` in Your SDK Workflow" section in the Yocto Project Application Development and the Extensible Software Development Kit (eSDK) manual.

The build process creates an entire Linux distribution from source and places it in your Build Directory under `tmp/deploy/images`. For detailed information on the build process using BitBake, see the "Images" section in the Yocto Project Reference Manual. You can also reference the "Building Images" section in the Yocto Project Quick Start.

The following figure and list overviews the build process:

1. Set up Your Host Development System to Support Development Using the Yocto Project: See the "Setting Up to Use the Yocto Project" section in the Yocto Project Quick Start for options on how to get a build host ready to use the Yocto Project.

2. Initialize the Build Environment: Initialize the build environment by sourcing the build environment script (i.e. `&OE_INIT_FILE;`).

3. Make Sure Your `local.conf` File is Correct: Ensure the `conf/local.conf` configuration file, which is found in the Build Directory, is set up how you want it. This file defines many aspects of the build environment including the target machine architecture through the `MACHINE` variable, the packaging format used during the build (`PACKAGE_CLASSES`), and a centralized tarball download directory through the `DL_DIR` variable.

4. Build the Image: Build the image using the `bitbake` command. For example, the following command builds the `core-image-minimal` image:

            $ bitbake core-image-minimal

   For information on BitBake, see the BitBake User Manual.

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