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-rw-r--r-- | documentation/dev-manual/dev-manual-common-tasks.xml | 74 | ||||
-rw-r--r-- | documentation/getting-started/getting-started-yp-intro.xml | 118 |
2 files changed, 120 insertions, 72 deletions
diff --git a/documentation/dev-manual/dev-manual-common-tasks.xml b/documentation/dev-manual/dev-manual-common-tasks.xml index 8e8b06fba1..f757465935 100644 --- a/documentation/dev-manual/dev-manual-common-tasks.xml +++ b/documentation/dev-manual/dev-manual-common-tasks.xml | |||
@@ -22,78 +22,12 @@ | |||
22 | multiple layers. | 22 | multiple layers. |
23 | Layers allow you to isolate different types of customizations from | 23 | Layers allow you to isolate different types of customizations from |
24 | each other. | 24 | each other. |
25 | You might find it tempting to keep everything in one layer when | 25 | For introductory information on the Yocto Project Layer Model, |
26 | working on a single project. | 26 | see the |
27 | However, the more modular your Metadata, the easier | 27 | "<ulink url='&YOCTO_DOCS_GS_URL;#the-yocto-project-layer-model'>The Yocto Project Layer Model</ulink>" |
28 | it is to cope with future changes. | 28 | section in the Getting Started With Yocto Project Manual. |
29 | </para> | ||
30 | |||
31 | <para> | ||
32 | To illustrate how layers are used to keep things modular, consider | ||
33 | machine customizations. | ||
34 | These types of customizations typically reside in a special layer, | ||
35 | rather than a general layer, called a Board Support Package (BSP) | ||
36 | Layer. | ||
37 | Furthermore, the machine customizations should be isolated from | ||
38 | recipes and Metadata that support a new GUI environment, | ||
39 | for example. | ||
40 | This situation gives you a couple of layers: one for the machine | ||
41 | configurations, and one for the GUI environment. | ||
42 | It is important to understand, however, that the BSP layer can | ||
43 | still make machine-specific additions to recipes within the GUI | ||
44 | environment layer without polluting the GUI layer itself | ||
45 | with those machine-specific changes. | ||
46 | You can accomplish this through a recipe that is a BitBake append | ||
47 | (<filename>.bbappend</filename>) file, which is described later | ||
48 | in this section. | ||
49 | <note> | ||
50 | For general information on BSP layer structure, see the | ||
51 | <ulink url='&YOCTO_DOCS_BSP_URL;#bsp'>Board Support Packages (BSP) - Developer's Guide</ulink>. | ||
52 | </note> | ||
53 | </para> | ||
54 | |||
55 | <para> | ||
56 | </para> | 29 | </para> |
57 | 30 | ||
58 | <section id='yocto-project-layers'> | ||
59 | <title>Layers</title> | ||
60 | |||
61 | <para> | ||
62 | The <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink> | ||
63 | contains both general layers and BSP | ||
64 | layers right out of the box. | ||
65 | You can easily identify layers that ship with a | ||
66 | Yocto Project release in the Source Directory by their | ||
67 | folder names. | ||
68 | Folders that represent layers typically have names that begin with | ||
69 | the string <filename>meta-</filename>. | ||
70 | <note> | ||
71 | It is not a requirement that a layer name begin with the | ||
72 | prefix <filename>meta-</filename>, but it is a commonly | ||
73 | accepted standard in the Yocto Project community. | ||
74 | </note> | ||
75 | For example, when you set up the Source Directory structure, | ||
76 | you will see several layers: | ||
77 | <filename>meta</filename>, | ||
78 | <filename>meta-skeleton</filename>, | ||
79 | <filename>meta-selftest</filename>, | ||
80 | <filename>meta-poky</filename>, and | ||
81 | <filename>meta-yocto-bsp</filename>. | ||
82 | Each of these folders represents a distinct layer. | ||
83 | </para> | ||
84 | |||
85 | <para> | ||
86 | As another example, if you set up a local copy of the | ||
87 | <filename>meta-intel</filename> Git repository | ||
88 | and then explore the folder of that general layer, | ||
89 | you will discover many Intel-specific BSP layers inside. | ||
90 | For more information on BSP layers, see the | ||
91 | "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP Layers</ulink>" | ||
92 | section in the Yocto Project Board Support Package (BSP) | ||
93 | Developer's Guide. | ||
94 | </para> | ||
95 | </section> | ||
96 | |||
97 | <section id='creating-your-own-layer'> | 31 | <section id='creating-your-own-layer'> |
98 | <title>Creating Your Own Layer</title> | 32 | <title>Creating Your Own Layer</title> |
99 | 33 | ||
diff --git a/documentation/getting-started/getting-started-yp-intro.xml b/documentation/getting-started/getting-started-yp-intro.xml index 8ea11baa75..c160c1cf62 100644 --- a/documentation/getting-started/getting-started-yp-intro.xml +++ b/documentation/getting-started/getting-started-yp-intro.xml | |||
@@ -265,9 +265,123 @@ | |||
265 | </section> | 265 | </section> |
266 | </section> | 266 | </section> |
267 | 267 | ||
268 | <section id='what-are-layers'> | 268 | <section id='the-yocto-project-layer-model'> |
269 | <title>What are Layers?</title> | 269 | <title>The Yocto Project Layer Model</title> |
270 | 270 | ||
271 | <para> | ||
272 | The Yocto Project's "Layer Model" is a development model for | ||
273 | embedded and IoT Linux creation that distinguishes the | ||
274 | Yocto Project from other simple build systems. | ||
275 | The Layer Model simultaneously supports collaboration and | ||
276 | customization. | ||
277 | Layers are repositories that contain related sets of instructions | ||
278 | that tell the OpenEmbedded build system what to do. | ||
279 | You can collaborate, share, and reuse layers. | ||
280 | </para> | ||
281 | |||
282 | <para> | ||
283 | Layers can contain changes to previous instructions or settings | ||
284 | at any time. | ||
285 | This powerful override capability is what allows you to customize | ||
286 | previously supplied collaborative or community layers to suit your | ||
287 | product requirements. | ||
288 | </para> | ||
289 | |||
290 | <para> | ||
291 | You use different layers to logically separate information in your | ||
292 | build. | ||
293 | As an example, you could have BSP, GUI, distro configuration, | ||
294 | middleware, or application layers. | ||
295 | Putting your entire build into one layer limits and complicates | ||
296 | future customization and reuse. | ||
297 | Isolating information into layers, on the other hand, helps | ||
298 | simplify future customizations and reuse. | ||
299 | You might find it tempting to keep everything in one layer when | ||
300 | working on a single project. | ||
301 | However, the more modular your Metadata, the easier | ||
302 | it is to cope with future changes. | ||
303 | <note><title>Notes</title> | ||
304 | <itemizedlist> | ||
305 | <listitem><para> | ||
306 | Use Board Support Package (BSP) layers from silicon | ||
307 | vendors when possible. | ||
308 | </para></listitem> | ||
309 | <listitem><para> | ||
310 | Familiarize yourself with the | ||
311 | <ulink url='https://caffelli-staging.yoctoproject.org/software-overview/layers/'>Yocto Project curated layer index</ulink> | ||
312 | or the | ||
313 | <ulink url='http://layers.openembedded.org/layerindex/branch/master/layers/'>OpenEmbedded layer index</ulink>. | ||
314 | The latter contains more layers but they are less | ||
315 | universally validated. | ||
316 | </para></listitem> | ||
317 | <listitem><para> | ||
318 | Layers support the inclusion of technologies, hardware | ||
319 | components, and software components. | ||
320 | The Yocto Project Compatible designation provides a | ||
321 | minimum level of standardization that contributes to a | ||
322 | strong ecosystem. | ||
323 | "YP Compatible" is applied to appropriate products and | ||
324 | software components such as BSPs, other OE-compatible | ||
325 | layers, and related open-source projects, allowing the | ||
326 | producer to use Yocto Project badges and branding | ||
327 | assets. | ||
328 | </para></listitem> | ||
329 | </itemizedlist> | ||
330 | </note> | ||
331 | </para> | ||
332 | |||
333 | <para> | ||
334 | To illustrate how layers are used to keep things modular, consider | ||
335 | machine customizations. | ||
336 | These types of customizations typically reside in a special layer, | ||
337 | rather than a general layer, called a BSP Layer. | ||
338 | Furthermore, the machine customizations should be isolated from | ||
339 | recipes and Metadata that support a new GUI environment, | ||
340 | for example. | ||
341 | This situation gives you a couple of layers: one for the machine | ||
342 | configurations, and one for the GUI environment. | ||
343 | It is important to understand, however, that the BSP layer can | ||
344 | still make machine-specific additions to recipes within the GUI | ||
345 | environment layer without polluting the GUI layer itself | ||
346 | with those machine-specific changes. | ||
347 | You can accomplish this through a recipe that is a BitBake append | ||
348 | (<filename>.bbappend</filename>) file, which is described later | ||
349 | in this section. | ||
350 | <note> | ||
351 | For general information on BSP layer structure, see the | ||
352 | <ulink url='&YOCTO_DOCS_BSP_URL;#bsp'>Board Support Packages (BSP) - Developer's Guide</ulink>. | ||
353 | </note> | ||
354 | </para> | ||
355 | |||
356 | <para> | ||
357 | The | ||
358 | <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink> | ||
359 | contains both general layers and BSP layers right out of the box. | ||
360 | You can easily identify layers that ship with a Yocto Project | ||
361 | release in the Source Directory by their names. | ||
362 | Layers typically have names that begin with the string | ||
363 | <filename>meta-</filename>. | ||
364 | <note> | ||
365 | It is not a requirement that a layer name begin with the | ||
366 | prefix <filename>meta-</filename>, but it is a commonly | ||
367 | accepted standard in the Yocto Project community. | ||
368 | </note> | ||
369 | For example, if you were to examine the | ||
370 | <ulink url='https://git.yoctoproject.org/cgit/cgit.cgi/poky/tree/'>tree view</ulink> | ||
371 | of the <filename>poky</filename> repository, you will see several | ||
372 | layers: <filename>meta</filename>, | ||
373 | <filename>meta-skeleton</filename>, | ||
374 | <filename>meta-selftest</filename>, | ||
375 | <filename>meta-poky</filename>, and | ||
376 | <filename>meta-yocto-bsp</filename>. | ||
377 | Each of these repositories represents a distinct layer. | ||
378 | </para> | ||
379 | |||
380 | <para> | ||
381 | For procedures on how to create layers, see the | ||
382 | "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>" | ||
383 | section in the Yocto Project Development Tasks Manual. | ||
384 | </para> | ||
271 | </section> | 385 | </section> |
272 | 386 | ||
273 | <section id='components-and-tools'> | 387 | <section id='components-and-tools'> |