## Welcome!

Welcome to the Yocto Project! The Yocto Project is an open-source collaboration project whose focus is developers of embedded Linux systems. The Yocto Project provides a development environment that eases application, kernel image, and Linux image development for embedded hardware systems. You can think of the Yocto Project as an umbrella over-arching many components, which include a build system, a reference or test distribution, and various tools all designed to enhance your embedded Linux development experience.

The Yocto Project uses a build host based on the OpenEmbedded (OE) project, which uses the BitBake tool, to construct complete images. The BitBake and OE components combine together to form a reference build host, historically known as Poky (Pah-kee). Tools exist that facilitate aspects of development such as layer creation to isolate your work, emulation for testing modules, modification of existing source code, integration of new or modified modules into existing images, and so forth.

Rather than go into great detail about the Yocto Project and its many capabilities, this quick start provides high-level practical information that lets you try out the Yocto Project. The quick start is written to help introduce you to the Yocto Project, get a feel for how to use it to build a Linux image or two, and provide you with a "road map" to other areas of interest for the new user.

### Tips

- For more introductory and conceptual information on the Yocto Project, see the Yocto Project Overview Manual.

- For guidance on where to look for information beyond this quick start, see the "Where To Go Next" section.

## Reference Build

This section of the quick start lets you work through setting up a build host and then shows you how to build two images: one for emulation and one for target hardware. The steps do not go into great detail but are rather focused on just letting you get set up and quickly experience the Yocto Project.

### Setting Up to Use the Yocto Project

Setting up to use the Yocto Project involves getting your build host ready. If you have a native Linux machine that runs a Yocto Project supported distribution as described by the "Supported Linux Distributions" section in the Yocto Project Reference Manual, you can prepare that machine as your build host. See the "Using a Native Linux Machine" section for more information.

If you do not want to use the Yocto Project on a native Linux machine, you can prepare your build host to use CROPS, which leverages Docker Containers. You can set up a build host for Windows, Mac, and Linux machines. See the "Using CROPS and Containers" section for more information.

#### Using CROPS and Containers

Follow these steps to get your build host set up with a Poky container that you can use to complete the build examples further down in the Quick Start:

1. Set Up to use CROss PlatformS (CROPS): Work through the first six steps of the procedure in the "Setting Up to Use CROss PlatformS (CROPS)" section of the Yocto Project Development Tasks Manual.

2. Set Up the Poky Container to Use the Yocto Project: Go to and follow the directions to set up the Poky container on your build host.

   Once you complete the setup instructions for your machine, you need to get a copy of the `poky` repository on your build host. See the "Yocto Project Release" section to continue.

#### Using a Native Linux Machine

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.e. recent releases of Fedora, openSUSE, CentOS, Debian, or Ubuntu).

- Build Host Packages Appropriate packages installed on the build host.

##### The Linux Distribution

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.

- Ubuntu

- Fedora

- openSUSE

- CentOS

- Debian

For a more detailed list of distributions that support the Yocto Project, see the "Supported Linux Distributions" section in the Yocto Project Reference Manual.

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.

##### The Build Host Packages

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 requirement), then 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.

Collectively, the number of required packages is large if you want to be able to cover all cases.

In general, you need to have root access and then install the required packages. Thus, the commands in the following section may or may not work depending on whether or not your Linux distribution has `sudo` installed.

The following list shows the required packages needed to build an image that runs on QEMU in graphical mode (e.g. essential plus graphics support). For lists of required packages for other scenarios, see the "Required Packages for the Host Development System" section in the Yocto Project Reference Manual.

- Ubuntu and Debian

           $ sudo apt-get install &UBUNTU_HOST_PACKAGES_ESSENTIAL; libsdl1.2-dev xterm

- Fedora

           $ sudo dnf install &FEDORA_HOST_PACKAGES_ESSENTIAL; SDL-devel xterm

- OpenSUSE

           $ sudo zypper install &OPENSUSE_HOST_PACKAGES_ESSENTIAL; libSDL-devel xterm

- CentOS

           $ sudo yum install &CENTOS_HOST_PACKAGES_ESSENTIAL; SDL-devel xterm

  ###### Notes

  - CentOS 6.x users need to ensure that the required versions of Git, tar and Python are available. For details, See the "Required Git, tar, and Python Versions" section in the Yocto Project Reference Manual for information.

  - Extra Packages for Enterprise Linux (i.e. `epel-release`) is a collection of packages from Fedora built on RHEL/CentOS for easy installation of packages not included in enterprise Linux by default. You need to install these packages separately.

  - The `makecache` command consumes additional Metadata from `epel-release`.

Once you complete the setup instructions for your machine, you need to get a copy of the `poky` repository on your build host. Continue with the "Yocto Project Release" section.

#### Yocto Project Release

Now that your build host has the right packages (native Linux machine) or you have the Poky container set up (CROPS), you need to get a copy of the Yocto Project. It is recommended that you get the latest Yocto Project release by setting up (cloning in Git terms) a local copy of the `poky` Git repository on your build host and then checking out the latest release. Doing so allows you to easily update to newer Yocto Project releases as well as contribute back to the Yocto Project.

Here is an example from a native Linux machine that is running Ubuntu.

If your build host is using a Poky container, you can use the same Git commands.

The following example clones the `poky` repository and then checks out the latest Yocto Project Release by tag (i.e. `&DISTRO_REL_TAG;`):

         $ git clone git://git.yoctoproject.org/poky
         Cloning into 'poky'...
         remote: Counting objects: 361782, done.
         remote: Compressing objects: 100% (87100/87100), done.
         remote: Total 361782 (delta 268619), reused 361439 (delta 268277)
         Receiving objects: 100% (361782/361782), 131.94 MiB | 6.88 MiB/s, done.
         Resolving deltas: 100% (268619/268619), done.
         Checking connectivity... done.
         $ git checkout tags/&DISTRO_REL_TAG; -b poky_&DISTRO;

The previous Git `checkout` command creates a local branch named `poky_&DISTRO;`. The files available to you in that branch exactly match the repository's files in the `&DISTRO_NAME_NO_CAP;` development branch at the time of the Yocto Project &DISTRO; release.

Rather than checking out the entire development branch of a release (i.e. the tip), which could be continuously changing while you are doing your development, you would check out a branch based on a release tag as shown in the previous example. Doing so provides you with an unchanging, stable set of files.

For more options and information about accessing Yocto Project related repositories, see the "Working With Yocto Project Source Files" section in the Yocto Project Development Tasks Manual.

### Building Images

You are now ready to give the Yocto Project a try. For this example, you will be using the command line to build your images.

A graphical user interface to the Yocto Project is available through Toaster. See the Toaster User Manual for more information.

The remainder of this quick start steps you through the following:

- Build a `qemux86` reference image and run it in the QEMU emulator.

- Easily change configurations so that you can quickly create a second image that you can load onto bootable media and actually boot target hardware. This example uses the MinnowBoard Turbot-compatible boards.

The steps in the following two sections do not provide detail, but rather provide minimal, working commands and examples designed to just get you started. For more details, see the appropriate manuals in the Yocto Project manual set.

#### Building an Image for Emulation

Use the following commands to build your image. The OpenEmbedded build system creates an entire Linux distribution, including the toolchain, from source.

##### Notes about Network Proxies

- By default, the build process searches for source code using a pre-determined order through a set of locations. If you are working behind a firewall and your build host is not set up for proxies, you could encounter problems with the build process when fetching source code (e.g. fetcher failures or Git failures).

- If you do not know your proxy settings, consult your local network infrastructure resources and get that information. A good starting point could also be to check your web browser settings. Finally, you can find more information on using the Yocto Project behind a firewall in the Yocto Project Reference Manual FAQ and on the "Working Behind a Network Proxy" wiki page.

1. Be Sure Your Build Host is Set Up: The steps to build an image in this section depend on your build host being properly set up. Be sure you have worked through the requirements described in the "Setting Up to Use the Yocto Project" section.

2. Check Out Your Branch: Be sure you are in the Source Directory (e.g. `poky`) and then check out the branch associated with the latest Yocto Project Release:

            $ cd ~/poky
            $ git checkout -b &DISTRO_NAME_NO_CAP; origin/&DISTRO_NAME_NO_CAP;

   Git's `checkout` command checks out the current Yocto Project release into a local branch whose name matches the release (i.e. `&DISTRO_NAME_NO_CAP;`). The local branch tracks the upstream branch of the same name. Creating your own branch based on the released branch ensures you are using the latest files for that release.

3. Initialize the Build Environment: Run the `&OE_INIT_FILE;` environment setup script to define the OpenEmbedded build environment on your build host.

            $ source &OE_INIT_FILE;

   Among other things, the script creates the Build Directory, which is `build` in this case and is located in the Source Directory. After the script runs, your current working directory is set to the Build Directory. Later, when the build completes, the Build Directory contains all the files created during the build.

4. Examine Your Local Configuration File: When you set up the build environment, a local configuration file named `local.conf` becomes available in a `conf` subdirectory of the Build Directory. Before using BitBake to start the build, you can look at this file and be sure your general configurations are how you want them:

   - To help conserve disk space during builds, you can add the following statement to your project's configuration file, which for this example is `poky/build/conf/local.conf`. Adding this statement deletes the work directory used for building a recipe once the recipe is built.

              INHERIT += "rm_work"

   - By default, the target machine for the build is `qemux86`, which produces an image that can be used in the QEMU emulator and is targeted at an Intel 32-bit based architecture. Further on in this example, this default is easily changed through the `MACHINE` variable so that you can quickly build an image for a different machine.

   - Another consideration before you build is the package manager used when creating the image. The default `local.conf` file selects the RPM package manager. You can control this configuration by using the ``PACKAGE_CLASSES`` variable.

     Selection of the package manager is separate from whether package management is used at runtime in the target image.

     For additional package manager selection information, see the "`package.bbclass`" section in the Yocto Project Reference Manual.

5. Start the Build: Continue with the following command to build an OS image for the target, which is `core-image-sato` in this example:

   Depending on the number of processors and cores, the amount of RAM, the speed of your Internet connection and other factors, the build process could take several hours the first time you run it. Subsequent builds run much faster since parts of the build are cached.

            $ bitbake core-image-sato

   If you experience a build error due to resources temporarily being unavailable and it appears you should not be having this issue, it might be due to the combination of a 4.3+ Linux kernel and `systemd` version 228+ (i.e. see this link for information).

   To work around this issue, you can try either of the following:

   - Try the build again.

   - Modify the "DefaultTasksMax" `systemd` parameter by uncommenting it and setting it to "infinity". You can find this parameter in the `system.conf` file located in `/etc/systemd` on most systems.

   For information on using the `bitbake` command, see the "BitBake" section in the Yocto Project Reference Manual, or see the "BitBake Command" section in the BitBake User Manual. For information on other targets, see the "Images" chapter in the Yocto Project Reference Manual.

6. Simulate Your Image Using QEMU: Once this particular image is built, you can start QEMU and run the image:

            $ runqemu qemux86

   If you want to learn more about running QEMU, see the "Using the Quick EMUlator (QEMU)" chapter in the Yocto Project Development Tasks Manual.

7. Exit QEMU: Exit QEMU by either clicking on the shutdown icon or by typing `Ctrl-C` in the QEMU transcript window from which you evoked QEMU.

#### Building an Image for Hardware

The following steps show how easy it is to set up to build an image for a new machine. These steps build an image for the MinnowBoard Turbot, which is supported by the Yocto Project and the `meta-intel` `intel-corei7-64` and `intel-core2-32` Board Support Packages (BSPs).

The MinnowBoard Turbot ships with 64-bit firmware. If you want to use the board in 32-bit mode, you must download the 32-bit firmware.

1. Create a Local Copy of the `meta-intel` Repository: Building an image for the MinnowBoard Turbot requires the `meta-intel` layer. Use the `git clone` command to create a local copy of the repository inside your Source Directory, which is `poky` in this example:

            $ cd $HOME/poky
            $ git clone git://git.yoctoproject.org/meta-intel
            Cloning into 'meta-intel'...
            remote: Counting objects: 14039, done.
            remote: Compressing objects: 100% (4471/4471), done.
            remote: Total 14039 (delta 8130), reused 13837 (delta 7947)
            Receiving objects: 100% (14039/14039), 4.27 MiB | 3.98 MiB/s, done.
            Resolving deltas: 100% (8130/8130), done.
            Checking connectivity... done.

   By default when you clone a Git repository, the "master" branch is checked out. Before you build your image that uses the `meta-intel` layer, you must be sure that both repositories (`meta-intel` and `poky`) are using the same releases. Because you used the `&DISTRO_REL_TAG;` tag when you checked out the `poky` repository by tag, you should use a `meta-intel` tag that corresponds with the release you used for `poky`. Consequently, you need to checkout out the "`&METAINTELVERSION;-&DISTRO_NAME_NO_CAP;-&YOCTO_DOC_VERSION;`" branch after cloning `meta-intel`:

            $ cd $HOME/poky/meta-intel
            $ git checkout tags/&METAINTELVERSION;-&DISTRO_NAME_NO_CAP;-&YOCTO_DOC_VERSION; -b meta-intel-&DISTRO_NAME_NO_CAP;-&YOCTO_DOC_VERSION;
            Switched to a new branch 'meta-intel-&DISTRO_NAME_NO_CAP;-&YOCTO_DOC_VERSION;'

   The previous Git `checkout` command creates a local branch named `meta-intel-&DISTRO_NAME_NO_CAP;-&YOCTO_DOC_VERSION;`. You have the option to name your local branch whatever you want by providing any name you like for "meta-intel-&DISTRO_NAME_NO_CAP;-&YOCTO_DOC_VERSION;" in the above example.

2. Configure the Build: To configure the build, you edit the `bblayers.conf` and `local.conf` files, both of which are located in the `build/conf` directory.

   Here is a quick way to make the edits. The first command uses the `bitbake-layers add-layer` command to add the `meta-intel` layer, which contains the `intel-core*` BSPs to the build. The second command selects the BSP by setting the `MACHINE` variable.

            $ cd $HOME/poky/build
            $ bitbake-layers add-layer "$HOME/poky/meta-intel"
            $ echo 'MACHINE = "intel-corei7-64"' >> conf/local.conf

   ##### Notes

   If you want a 64-bit build, use the following:

            $ echo 'MACHINE = "intel-corei7-64"' >> conf/local.conf

   If you want 32-bit images, use the following:

            $ echo 'MACHINE = "intel-core2-32"' >> conf/local.conf

3. Build an Image for MinnowBoard Turbot: The type of image you build depends on your goals. For example, the previous build created a `core-image-sato` image, which is an image with Sato support. It is possible to build many image types for the MinnowBoard Turbot. Some possibilities are `core-image-base`, which is a console-only image. Another choice could be a `core-image-full-cmdline`, which is another console-only image but has more full-features Linux system functionality installed. For types of images you can build using the Yocto Project, see the "Images" chapter in the Yocto Project Reference Manual.

   Because configuration changes are minimal to set up for this second build, the OpenEmbedded build system can re-use files from previous builds as much as possible. Re-using files means this second build will be much faster than an initial build. For this example, the `core-image-base` image is built:

            $ bitbake core-image-base

   If you experience a build error due to resources temporarily being unavailable and it appears you should not be having this issue, it might be due to the combination of a 4.3+ Linux kernel and `systemd` version 228+ (i.e. see this link for information).

   To work around this issue, you can try either of the following:

   - Try the build again.

   - Modify the "DefaultTasksMax" `systemd` parameter by uncommenting it and setting it to "infinity". You can find this parameter in the `system.conf` file located in `/etc/systemd` on most systems.

   Once the build completes, the resulting console-only image is located in the Build Directory here:

            tmp/deploy/images/intel-corei7-64/core-image-base-intel-corei7-64.wic

4. Write the Image: You can write the image just built to a bootable media (e.g. a USB key, SATA drive, SD card, etc.) using the `dd` utility:

            $ sudo dd if=tmp/deploy/images/intel-corei7-64/core-image-base-intel-corei7-64.wic of=TARGET_DEVICE

   In the previous command, the `TARGET_DEVICE` is the device node in the host machine (e.g. `/dev/sdc`, which is most likely a USB stick, or `/dev/mmcblk0`, which is most likely an SD card).

5. Boot the Hardware: With the boot device provisioned, you can insert the media into the MinnowBoard Turbot and boot the hardware. The board should automatically detect the media and boot to the bootloader and subsequently the operating system.

   If the board does not boot automatically, you can boot it manually from the EFI shell as follows:

            Shell> connect -r
            Shell> map -r
            Shell> fs0:
            Shell> bootx64

   For a 32-bit image use the following:

            Shell> bootia32

## Where To Go Next

Now that you have experienced using the Yocto Project, you might be asking yourself "What now?" This next section of the Quick Start provides some "sign posts" that can help you find additional information depending on what you want to accomplish with the Yocto Project. The section provides a list of resources for more information, some links into sections that provide basic tasks, and some links into more specialized areas that go beyond building images.

You can also see the page for suggested sets of Yocto Project manuals designed for various levels of experience.

### Additional Resources

The Yocto Project has many sources of information including the website, wiki pages, and user manuals. This section lists resources you might find helpful:

- Website: The Yocto Project Website provides background information, the latest builds, breaking news, full development documentation, and access to a rich Yocto Project Development Community into which you can tap.

- FAQs: Lists commonly asked Yocto Project questions and answers. You can find two FAQs: Yocto Project FAQ on a wiki, and the "FAQ" chapter in the Yocto Project Reference Manual.

- Developer Screencast: The Getting Started with the Yocto Project - New Developer Screencast Tutorial provides a 30-minute video created for users unfamiliar with the Yocto Project but familiar with Linux build hosts. While this screencast is somewhat dated, the introductory and fundamental concepts are useful for the beginner.

- Yocto Project Implementation of Bugzilla: The Yocto Project uses its own implementation of Bugzilla that you can find here. Bugzilla allows you to report and track the progress of defects and improvements to the Yocto Project.

- Yocto Project Wiki: The Yocto Project Wiki provides additional information on where to go next when ramping up with the Yocto Project, release information, project planning, and QA information.

- Yocto Project Mailing Lists: Related mailing lists provide a forum for discussion, patch submission and announcements. Several mailing lists exist and are grouped according to areas of concern. See the "Mailing lists" section in the Yocto Project Reference Manual for a complete list of Yocto Project mailing lists.

- Comprehensive List of Links and Other Documentation: The "Links and Related Documentation" section in the Yocto Project Reference Manual provides a comprehensive list of all related links and other user documentation.

### Guided Examples

Depending on what you primary interests are with the Yocto Project, you could consider any of the following:

- Add a Layer for Hardware Support: For steps on how to add a Board Support Package (BSP) layer that supports specific hardware, see the "Creating a new BSP Layer Using the `bitbake-layers` Script" section in the Yocto Project Board Support Package (BSP) Developer's Guide. For background information on BSP layers, see the "BSP Layers" section in the same manual.

- Add a Layer for Software: For steps on how to add a general layer for software, see the "Creating a General Layer Using the `bitbake-layers` Script" section in the Yocto Project Development Tasks Manual. For background information on layers in general, see the "Understanding and Creating Layers" section in the same manual.

- Write a New Recipe: For steps on how to write a new recipe, see the "Writing a New Recipe" section in the Yocto Project Development Tasks Manual.

- Create a Layer for Customizations: This is a step suggested by Richard. I don't know the distinction between creating a layer for customizations and creating a general layer as pointed out earlier for creating a general layer (i.e. a layer for software). I need some help on this bullet item.

- Add a Custom Kernel: For steps on how to modify and create your own custom kernel, see the "Using `devtool` to Patch the Kernel" section in the Yocto Project Linux Kernel Development Manual.

- Change the Default Kernel Configuration: For steps on how to configure the kernel, see the "Configuring the Kernel" section in the Yocto Project Linux Kernel Development Manual.

- Submit a Change to the Yocto Project: For steps on how to submit a change or patch to the Yocto Project, see the "Submitting a Change to the Yocto Project" section in the Yocto Project Development Tasks Manual.

### Going Beyond Builds

This section presents some pointers to topics that go beyond building images:

- The OpenEmbedded Layer Index: This index shows layers that exist for use with the Yocto Project. More times than not, you can find layers for your own use or layers that are close to what you need and can be leveraged when creating your own layers. See http://layers.openembedded.org/layerindex/branch/master/layers/ for the layer index.

- Yocto Project Autobuilder: Autobuilders provide automatic building in a development or production environment. For information on the autobuilders used by the Yocto Project, see the "Setting Up a Team Yocto Project Development Environment" section of the Yocto Project Development Tasks Manual. You can also see the http://autobuilder.yoctoproject.org/ link.

- Yocto Project Compatibility: When you create layers, you can take steps to make sure your layer is compatible with the Yocto Project. See the "Making Sure Your Layer is Compatible With Yocto Project" section in the Yocto Project Development Tasks Manual for more information.

- Auto Upgrade Tools: This is a step suggested by Richard. I don't know what this is and need help with this bullet item.

- Patches and Patchwork: This is a step suggested by Richard. I don't know what this is and need help with this bullet item.

- Pseudo: Pseudo gives the illusion of running under root and is is used during the image generation process. I don't have much on this in the manual set. Is there any more information we can leverage? For information on Fakeroot and Pseudo, see the "Fakeroot and Pseudo" section in the Yocto Project Reference Manual.

- OPKG: OPKG is a file management system. I am not sure what Richard had in mind for suggesting this "beyond builds" topic. I have one reference at "Using IPK" in the Yocto Project Development Tasks Manual that is the bulk of my known information. I need more help with this bullet item.

- Team Yocto Project Development Environments: For information on Yocto Project development team environments, see the "Setting Up a Team Yocto Project Development Environment" section in the Yocto Project Development Tasks Manual.