poky/documentation/transitioning-to-a-custom-environment.rst - openbmc/openbmc - Gitiles

 .. SPDX-License-Identifier: CC-BY-SA-2.0-UK

 =============================================================
 Transitioning to a custom environment for systems development
 =============================================================

 |

 .. note::

    So you've finished the :doc:`brief-yoctoprojectqs/index` and
    glanced over the document :doc:`what-i-wish-id-known`, the latter contains
    important information learned from other users. You're well prepared. But
    now, as you are starting your own project, it isn't exactly straightforward what
    to do. And, the documentation is daunting. We've put together a few hints to
    get you started.

 #. **Make a list of the processor, target board, technologies, and capabilities
    that will be part of your project**.
    You will be finding layers with recipes and other metadata that support these
    things, and adding them to your configuration. (See #3)

 #. **Set up your board support**.
    Even if you're using custom hardware, it might be easier to start with an
    existing target board that uses the same processor or at least the same
    architecture as your custom hardware. Knowing the board already has a
    functioning Board Support Package (BSP) within the project makes it easier
    for you to get comfortable with project concepts.

 #. **Find and acquire the best BSP for your target**.
    Use the :yocto_home:`Yocto Project curated layer index
    </software-overview/layers/>` or even the :oe_layerindex:`OpenEmbedded
    layer index <>` to find and acquire the best BSP for your
    target board. The Yocto Project layer index BSPs are regularly validated. The
    best place to get your first BSP is from your silicon manufacturer or board
    vendor – they can point you to their most qualified efforts. In general, for
    Intel silicon use meta-intel, for Texas Instruments use meta-ti, and so
    forth. Choose a BSP that has been tested with the same Yocto Project release
    that you've downloaded. Be aware that some BSPs may not be immediately
    supported on the very latest release, but they will be eventually.

    You might want to start with the build specification that Poky provides
    (which is reference embedded distribution) and then add your newly chosen
    layers to that. Here is the information :ref:`about adding layers
    <dev-manual/common-tasks:Understanding and Creating Layers>`.

 #. **Based on the layers you've chosen, make needed changes in your
    configuration**.
    For instance, you've chosen a machine type and added in the corresponding BSP
    layer. You'll then need to change the value of the :term:`MACHINE` variable in your
    configuration file (build/local.conf) to point to that same machine
    type. There could be other layer-specific settings you need to change as
    well. Each layer has a ``README`` document that you can look at for this type of
    usage information.

 #. **Add a new layer for any custom recipes and metadata you create**.
    Use the ``bitbake-layers create-layer`` tool for Yocto Project 2.4+
    releases. If you are using a Yocto Project release earlier than 2.4, use the
    ``yocto-layer create`` tool. The ``bitbake-layers`` tool also provides a number
    of other useful layer-related commands. See
    :ref:`dev-manual/common-tasks:creating a general layer using the
    \`\`bitbake-layers\`\` script` section.

 #. **Create your own layer for the BSP you're going to use**.
    It is not common that you would need to create an entire BSP from scratch
    unless you have a *really* special device. Even if you are using an existing
    BSP, :ref:`create your own layer for the BSP <bsp-guide/bsp:creating a new
    bsp layer using the \`\`bitbake-layers\`\` script>`. For example, given a
    64-bit x86-based machine, copy the conf/intel-corei7-64 definition and give
    the machine a relevant name (think board name, not product name). Make sure
    the layer configuration is dependent on the meta-intel layer (or at least,
    meta-intel remains in your bblayers.conf). Now you can put your custom BSP
    settings into your layer and you can re-use it for different applications.

 #. **Write your own recipe to build additional software support that isn't
    already available in the form of a recipe**.
    Creating your own recipe is especially important for custom application
    software that you want to run on your device. Writing new recipes is a
    process of refinement. Start by getting each step of the build process
    working beginning with fetching all the way through packaging. Next, run the
    software on your target and refine further as needed. See :ref:`Writing a New
    Recipe <dev-manual/common-tasks:writing a new recipe>` in the
    Yocto Project Development Tasks Manual for more information.

 #. **Now you're ready to create an image recipe**.
    There are a number of ways to do this. However, it is strongly recommended
    that you have your own image recipe - don't try appending to existing image
    recipes. Recipes for images are trivial to create and you usually want to
    fully customize their contents.

 #. **Build your image and refine it**.
    Add what's missing and fix anything that's broken using your knowledge of the
    :ref:`workflow <sdk-manual/extensible:using \`\`devtool\`\` in your sdk
    workflow>` to identify where issues might be occurring.

 #. **Consider creating your own distribution**.
    When you get to a certain level of customization, consider creating your own
    distribution rather than using the default reference distribution.

    Distribution settings define the packaging back-end (e.g. rpm or other) as
    well as the package feed and possibly the update solution. You would create
    your own distribution in a new layer inheriting from Poky but overriding what
    needs to change for your distribution. If you find yourself adding a lot of
    configuration to your local.conf file aside from paths and other typical
    local settings, it's time to :ref:`consider creating your own distribution
    <dev-manual/common-tasks:creating your own distribution>`.

    You can add product specifications that can customize the distribution if
    needed in other layers. You can also add other functionality specific to the
    product. But to update the distribution, not individual products, you update
    the distribution feature through that layer.

 #. **Congratulations! You're well on your way.**
    Welcome to the Yocto Project community.

 .. include:: /boilerplate.rst
	.. SPDX-License-Identifier: CC-BY-SA-2.0-UK

	=============================================================
	Transitioning to a custom environment for systems development
	=============================================================

	\|

	.. note::

	So you've finished the :doc:`brief-yoctoprojectqs/index` and
	glanced over the document :doc:`what-i-wish-id-known`, the latter contains
	important information learned from other users. You're well prepared. But
	now, as you are starting your own project, it isn't exactly straightforward what
	to do. And, the documentation is daunting. We've put together a few hints to
	get you started.

	#. **Make a list of the processor, target board, technologies, and capabilities
	that will be part of your project**.
	You will be finding layers with recipes and other metadata that support these
	things, and adding them to your configuration. (See #3)

	#. Set up your board support.
	Even if you're using custom hardware, it might be easier to start with an
	existing target board that uses the same processor or at least the same
	architecture as your custom hardware. Knowing the board already has a
	functioning Board Support Package (BSP) within the project makes it easier
	for you to get comfortable with project concepts.

	#. Find and acquire the best BSP for your target.
	Use the :yocto_home:`Yocto Project curated layer index
	</software-overview/layers/>` or even the :oe_layerindex:`OpenEmbedded
	layer index <>` to find and acquire the best BSP for your
	target board. The Yocto Project layer index BSPs are regularly validated. The
	best place to get your first BSP is from your silicon manufacturer or board
	vendor – they can point you to their most qualified efforts. In general, for
	Intel silicon use meta-intel, for Texas Instruments use meta-ti, and so
	forth. Choose a BSP that has been tested with the same Yocto Project release
	that you've downloaded. Be aware that some BSPs may not be immediately
	supported on the very latest release, but they will be eventually.

	You might want to start with the build specification that Poky provides
	(which is reference embedded distribution) and then add your newly chosen
	layers to that. Here is the information :ref:`about adding layers
	<dev-manual/common-tasks:Understanding and Creating Layers>`.

	#. **Based on the layers you've chosen, make needed changes in your
	configuration**.
	For instance, you've chosen a machine type and added in the corresponding BSP
	layer. You'll then need to change the value of the :term:`MACHINE` variable in your
	configuration file (build/local.conf) to point to that same machine
	type. There could be other layer-specific settings you need to change as
	well. Each layer has a ``README`` document that you can look at for this type of
	usage information.

	#. Add a new layer for any custom recipes and metadata you create.
	Use the ``bitbake-layers create-layer`` tool for Yocto Project 2.4+
	releases. If you are using a Yocto Project release earlier than 2.4, use the
	``yocto-layer create`` tool. The ``bitbake-layers`` tool also provides a number
	of other useful layer-related commands. See
	:ref:`dev-manual/common-tasks:creating a general layer using the
	\`\`bitbake-layers\`\` script` section.

	#. Create your own layer for the BSP you're going to use.
	It is not common that you would need to create an entire BSP from scratch
	unless you have a really special device. Even if you are using an existing
	BSP, :ref:`create your own layer for the BSP <bsp-guide/bsp:creating a new
	bsp layer using the \`\`bitbake-layers\`\` script>`. For example, given a
	64-bit x86-based machine, copy the conf/intel-corei7-64 definition and give
	the machine a relevant name (think board name, not product name). Make sure
	the layer configuration is dependent on the meta-intel layer (or at least,
	meta-intel remains in your bblayers.conf). Now you can put your custom BSP
	settings into your layer and you can re-use it for different applications.

	#. **Write your own recipe to build additional software support that isn't
	already available in the form of a recipe**.
	Creating your own recipe is especially important for custom application
	software that you want to run on your device. Writing new recipes is a
	process of refinement. Start by getting each step of the build process
	working beginning with fetching all the way through packaging. Next, run the
	software on your target and refine further as needed. See :ref:`Writing a New
	Recipe <dev-manual/common-tasks:writing a new recipe>` in the
	Yocto Project Development Tasks Manual for more information.

	#. Now you're ready to create an image recipe.
	There are a number of ways to do this. However, it is strongly recommended
	that you have your own image recipe - don't try appending to existing image
	recipes. Recipes for images are trivial to create and you usually want to
	fully customize their contents.

	#. Build your image and refine it.
	Add what's missing and fix anything that's broken using your knowledge of the
	:ref:`workflow <sdk-manual/extensible:using \`\`devtool\`\` in your sdk
	workflow>` to identify where issues might be occurring.

	#. Consider creating your own distribution.
	When you get to a certain level of customization, consider creating your own
	distribution rather than using the default reference distribution.

	Distribution settings define the packaging back-end (e.g. rpm or other) as
	well as the package feed and possibly the update solution. You would create
	your own distribution in a new layer inheriting from Poky but overriding what
	needs to change for your distribution. If you find yourself adding a lot of
	configuration to your local.conf file aside from paths and other typical
	local settings, it's time to :ref:`consider creating your own distribution
	<dev-manual/common-tasks:creating your own distribution>`.

	You can add product specifications that can customize the distribution if
	needed in other layers. You can also add other functionality specific to the
	product. But to update the distribution, not individual products, you update
	the distribution feature through that layer.

	#. Congratulations! You're well on your way.
	Welcome to the Yocto Project community.

	.. include:: /boilerplate.rst