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1 | .. SPDX-License-Identifier: CC-BY-2.0-UK | ||
2 | |||
3 | ============================================================= | ||
4 | Transitioning to a custom environment for systems development | ||
5 | ============================================================= | ||
6 | |||
7 | | | ||
8 | |||
9 | .. note:: | ||
10 | |||
11 | So you've finished the :doc:`brief-yoctoprojectqs/brief-yoctoprojectqs` and | ||
12 | glanced over the document :doc:`what-i-wish-id-known`, the latter contains | ||
13 | important information learned from other users. You’re well prepared. But | ||
14 | now, as you are starting your own project, isn’t exactly straightforward what | ||
15 | to do. And, the documentation is daunting. We’ve put together a few hints to | ||
16 | get you started. | ||
17 | |||
18 | #. **Make a list of the processor, target board, technologies, and capabilities | ||
19 | that will be part of your project**. | ||
20 | You will be finding layers with recipes and other metadata that support these | ||
21 | things, and adding them to your configuration. (See #3) | ||
22 | |||
23 | #. **Set up your board support**. | ||
24 | Even if you’re using custom hardware, it might be easier to start with an | ||
25 | existing target board that uses the same processor or at least the same | ||
26 | architecture as your custom hardware. Knowing the board already has a | ||
27 | functioning Board Support Package (BSP) within the project makes it easier | ||
28 | for you to get comfortable with project concepts. | ||
29 | |||
30 | #. **Find and acquire the best BSP for your target**. | ||
31 | Use the :yocto_home:`Yocto Project curated layer index | ||
32 | </software-overview/layers/>` or even the `OpenEmbedded layer index | ||
33 | <https://layers.openembedded.org>`_ to find and acquire the best BSP for your | ||
34 | target board. The Yocto Project layer index BSPs are regularly validated. The | ||
35 | best place to get your first BSP is from your silicon manufacturer or board | ||
36 | vendor – they can point you to their most qualified efforts. In general, for | ||
37 | Intel silicon use meta-intel, for Texas Instruments use meta-ti, and so | ||
38 | forth. Choose a BSP that has been tested with the same Yocto Project release | ||
39 | that you’ve downloaded. Be aware that some BSPs may not be immediately | ||
40 | supported on the very latest release, but they will be eventually. | ||
41 | |||
42 | You might want to start with the build specification that Poky provides | ||
43 | (which is reference embedded distribution) and then add your newly chosen | ||
44 | layers to that. Here is the information :ref:`about adding layers | ||
45 | <dev-manual/dev-manual-common-tasks:Understanding and Creating Layers>`. | ||
46 | |||
47 | #. **Based on the layers you've chosen, make needed changes in your | ||
48 | configuration**. | ||
49 | For instance, you’ve chosen a machine type and added in the corresponding BSP | ||
50 | layer. You'll then need to change the value of the MACHINE variable in your | ||
51 | configuration file (build/local.conf) to point to that same machine | ||
52 | type. There could be other layer-specific settings you need to change as | ||
53 | well. Each layer has a README document that you can look at for this type of | ||
54 | usage information. | ||
55 | |||
56 | #. **Add a new layer for any custom recipes and metadata you create**. | ||
57 | Use the "bitbake-layers create-layer" tool for Yocto Project 2.4+ | ||
58 | releases. If you are using a Yocto Project release earlier than 2.4, use the | ||
59 | "yocto-layer create" tool. The "bitbake-layers" tool also provides a number | ||
60 | of other useful layer-related commands. See | ||
61 | :ref:`dev-manual/dev-manual-common-tasks:creating a general layer using the | ||
62 | \`\`bitbake-layers\`\` script` section. | ||
63 | |||
64 | #. **Create your own layer for the BSP you're going to use**. | ||
65 | It is not common that you would need to create an entire BSP from scratch | ||
66 | unless you have a *really* special device. Even if you are using an existing | ||
67 | BSP, :ref:`create your own layer for the BSP <bsp-guide/bsp:creating a new | ||
68 | bsp layer using the \`\`bitbake-layers\`\` script>`. For example, given a | ||
69 | 64-bit x86-based machine, copy the conf/intel-corei7-64 definition and give | ||
70 | it a machine a relevant name (think board name, not product name). Make sure | ||
71 | the layer configuration is dependent on the meta-intel layer (or at least, | ||
72 | meta-intel remains in your bblayers.conf). Now you can put your custom BSP | ||
73 | settings into your layer and you can re-use it for different applications. | ||
74 | |||
75 | #. **Write your own recipe to build additional software support that isn't | ||
76 | already available in the form of a recipe**. | ||
77 | Creating your own recipe is especially important for custom application | ||
78 | software that you want to run on your device. Writing new recipes is a | ||
79 | process of refinement. Start by getting each step of the build process | ||
80 | working beginning with fetching all the way through packaging. Next, run the | ||
81 | software on your target and refine further as needed. See :ref:`Writing a New | ||
82 | Recipe <dev-manual/dev-manual-common-tasks:writing a new recipe>` in the | ||
83 | Yocto Project Development Tasks Manual for more information. | ||
84 | |||
85 | #. **Now you’re ready to create an image recipe**. | ||
86 | There are a number of ways to do this. However, it is strongly recommended | ||
87 | that you have your own image recipe - don’t try appending to existing image | ||
88 | recipes. Recipes for images are trivial to create and you usually want to | ||
89 | fully customize their contents. | ||
90 | |||
91 | #. **Build your image and refine it**. | ||
92 | Add what’s missing and fix anything that's broken using your knowledge of the | ||
93 | :ref:`workflow <sdk-manual/sdk-extensible:using \`\`devtool\`\` in your sdk | ||
94 | workflow>` to identify where issues might be occurring. | ||
95 | |||
96 | #. **Consider creating your own distribution**. | ||
97 | When you get to a certain level of customization, consider creating your own | ||
98 | distribution rather than using the default reference distribution. | ||
99 | |||
100 | Distribution settings define the packaging back-end (e.g. rpm or other) as | ||
101 | well as the package feed and possibly the update solution. You would create | ||
102 | your own distribution in a new layer inheriting from Poky but overriding what | ||
103 | needs to change for your distribution. If you find yourself adding a lot of | ||
104 | configuration to your local.conf file aside from paths and other typical | ||
105 | local settings, it's time to :ref:`consider creating your own distribution | ||
106 | <dev-manual/dev-manual-common-tasks:creating your own distribution>`. | ||
107 | |||
108 | You can add product specifications that can customize the distribution if | ||
109 | needed in other layers. You can also add other functionality specific to the | ||
110 | product. But to update the distribution, not individual products, you update | ||
111 | the distribution feature through that layer. | ||
112 | |||
113 | #. **Congratulations! You're well on your way.** | ||
114 | Welcome to the Yocto Project community. | ||
115 | |||
116 | .. include:: /boilerplate.rst | ||