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authorScott Rifenbark <srifenbark@gmail.com>2017-09-06 14:51:17 -0700
committerRichard Purdie <richard.purdie@linuxfoundation.org>2017-09-13 18:00:18 +0100
commitd4be6ea72a18074282e3d9bfc0b70a65658736f2 (patch)
tree535d32272f03101ad4a28e0da1139c1a6fb2b35d /documentation
parent2bfabb55395e3eeec984523ccdb60d9456151339 (diff)
downloadpoky-d4be6ea72a18074282e3d9bfc0b70a65658736f2.tar.gz
kernel-dev: Updates to the intro chapter
I moved the flow diagram up higher and completely removed the procedures to get the build host ready for kernel development. Those are now in the common tasks chapter. Lots of rewriting Signen-off-by: Scott Rifenbark <srifenbark@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'documentation')
-rw-r--r--documentation/kernel-dev/kernel-dev-intro.xml443
1 files changed, 80 insertions, 363 deletions
diff --git a/documentation/kernel-dev/kernel-dev-intro.xml b/documentation/kernel-dev/kernel-dev-intro.xml
index 17ff5c7877..2490087b7a 100644
--- a/documentation/kernel-dev/kernel-dev-intro.xml
+++ b/documentation/kernel-dev/kernel-dev-intro.xml
@@ -89,270 +89,50 @@
89 recipes, an alternative exists by which you can use the Yocto 89 recipes, an alternative exists by which you can use the Yocto
90 Project Linux kernel tools with your own kernel sources. 90 Project Linux kernel tools with your own kernel sources.
91 </para> 91 </para>
92</section>
93
94<section id='preparing-the-build-host-to-work-on-the-kernel'>
95 <title>Preparing the Build Host to Work on the Kernel</title>
96 92
97 <para> 93 <para>
98 Before you can do any kernel development, you need to be 94 The remainder of this manual provides instructions for completing
99 sure your build host is set up to use the Yocto Project. 95 specific Linux kernel development tasks.
100 For information on how to get set up, see the 96 These instructions assume you are comfortable working with
101 "<ulink url='&YOCTO_DOCS_DEV_URL;#setting-up-the-development-host-to-use-the-yocto-project'>Setting Up to Use the Yocto Project</ulink>" 97 <ulink url='http://openembedded.org/wiki/Bitbake'>BitBake</ulink>
102 section in the Yocto Project Development Manual. 98 recipes and basic open-source development tools.
103 Part of preparing the system is creating a local Git 99 Understanding these concepts will facilitate the process of working
104 repository of the 100 with the kernel recipes.
105 <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink> 101 If you find you need some additional background, please be sure to
106 (<filename>poky</filename>) on your system. 102 review and understand the following documentation:
107 Follow the steps in the 103 <itemizedlist>
108 "<ulink url='&YOCTO_DOCS_DEV_URL;#cloning-the-poky-repository'>Cloning the <filename>poky</filename> Repository</ulink>" 104 <listitem><para>
109 section in the Yocto Project Development Manual to set up your 105 <ulink url='&YOCTO_DOCS_QS_URL;'>Yocto Project Quick Start</ulink>
110 Source Directory. 106 </para></listitem>
111 <note> 107 <listitem><para>
112 Be sure you check out the appropriate development branch or 108 <ulink url='&YOCTO_DOCS_SDK_URL;#using-devtool-in-your-sdk-workflow'><filename>devtool</filename> workflow</ulink>
113 by tag to get the version of Yocto Project you want. 109 as described in the Yocto Project Software Development Kit
114 See the 110 (SDK) Developer's Guide.
115 "<ulink url='&YOCTO_DOCS_DEV_URL;#checking-out-by-branch-in-poky'>Checking Out by Branch in Poky</ulink>" 111 </para></listitem>
116 and 112 <listitem><para>
117 "<ulink url='&YOCTO_DOCS_DEV_URL;#checkout-out-by-tag-in-poky'>Checking Out by Tag in Poky</ulink>" 113 The
118 sections in the Yocto Project Development Manual for more 114 "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>" section
119 information. 115 in the Yocto Project Development Manual
120 </note> 116 </para></listitem>
117 <listitem><para>
118 The
119 "<link linkend='kernel-modification-workflow'>Kernel Modification Workflow</link>"
120 section.
121 </para></listitem>
122 </itemizedlist>
121 </para> 123 </para>
122 124
123 <para> 125 <para>
124 Kernel development is best accomplished using 126 Finally, while this document focuses on the manual creation of
125 <ulink url='&YOCTO_DOCS_SDK_URL;#using-devtool-in-your-sdk-workflow'><filename>devtool</filename></ulink> 127 recipes, patches, and configuration files, the Yocto Project
126 and not through traditional kernel workflow methods. 128 Board Support Package (BSP) tools are available to automate
127 The remainder of this section provides information for both scenarios. 129 this process with existing content and work well to create the
130 initial framework and boilerplate code.
131 For details on these tools, see the
132 "<ulink url='&YOCTO_DOCS_BSP_URL;#using-the-yocto-projects-bsp-tools'>Using the Yocto Project's BSP Tools</ulink>"
133 section in the Yocto Project Board Support Package (BSP) Developer's
134 Guide.
128 </para> 135 </para>
129
130 <section id='getting-ready-to-develop-using-devtool'>
131 <title>Getting Ready to Develop using <filename>devtool</filename></title>
132
133 <para>
134 Follow these steps to prepare to update the kernel image using
135 <filename>devtool</filename>.
136 Completing this procedure leaves you with a clean kernel image
137 and ready to make modifications as described in the
138 "<link linkend='using-devtool-to-patch-the-kernel'>Using <filename>devtool</filename> to Patch the Kernel</link>"
139 section:
140 <orderedlist>
141 <listitem><para>
142 <emphasis>Initialize the BitBake Environment:</emphasis>
143 Before building an extensible SDK, you need to
144 initialize the BitBake build environment by sourcing a
145 build environment script
146 (i.e. <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>oe-init-build-env</filename></ulink>
147 or
148 <ulink url='&YOCTO_DOCS_REF_URL;#structure-memres-core-script'><filename>oe-init-build-env-memres</filename></ulink>):
149 <literallayout class='monospaced'>
150 $ cd ~/poky
151 $ source oe-init-build-env
152 </literallayout>
153 <note>
154 The previous commands assume the
155 <ulink url='&YOCTO_DOCS_REF_URL;#source-repositories'>Source Repositories</ulink>
156 (i.e. <filename>poky</filename>) have been cloned
157 using Git and the local repository is named
158 "poky".
159 </note>
160 </para></listitem>
161 <listitem><para>
162 <emphasis>Prepare Your <filename>local.conf</filename> File:</emphasis>
163 By default, the
164 <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
165 variable is set to "qemux86", which is fine if you are
166 building for the QEMU emulator in 32-bit mode.
167 However, if you are not, you need to set the
168 <filename>MACHINE</filename> variable appropriately in
169 your <filename>conf/local.conf</filename> file found in the
170 <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
171 (i.e. <filename>~/poky/build</filename> in this example).
172 </para>
173
174 <para>Also, since you are preparing to work on the kernel
175 image, you need to set the
176 <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS'><filename>MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS</filename></ulink>
177 variable to include kernel modules.</para>
178
179 <para>This example uses the default "qemux86" for the
180 <filename>MACHINE</filename> variable but needs to
181 add the "kernel-modules":
182 <literallayout class='monospaced'>
183 MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-modules"
184 </literallayout>
185 </para></listitem>
186 <listitem><para>
187 <emphasis>Create a Layer for Patches:</emphasis>
188 You need to create a layer to hold patches created
189 for the kernel image.
190 You can use the <filename>yocto-layer</filename> command
191 as follows:
192 <literallayout class='monospaced'>
193 $ cd ~/poky
194 $ yocto-layer create my-kernel -o ../meta-my-kernel
195 Please enter the layer priority you'd like to use for the layer: [default: 6]
196 Would you like to have an example recipe created? (y/n) [default: n]
197 Would you like to have an example bbappend file created? (y/n) [default: n]
198
199 New layer created in ../meta-my-kernel.
200
201 Don't forget to add it to your BBLAYERS (for details see ../meta-my-kernel/README).
202 </literallayout>
203 </para></listitem>
204 <listitem><para>
205 <emphasis>Inform the BitBake Build Environment About Your Layer:</emphasis>
206 As directed when you created your layer, you need to add
207 the layer to the
208 <ulink url='&YOCTO_DOCS_REF_URL;#var-BBLAYERS'><filename>BBLAYERS</filename></ulink>
209 variable in the <filename>bblayers.conf</filename> file
210 as follows:
211 <literallayout class='monospaced'>
212 $ cd ~/poky/build
213 $ bitbake-layers add-layer ../../meta-my-kernel
214 </literallayout>
215 </para></listitem>
216 <listitem><para>
217 <emphasis>Build the Extensible SDK:</emphasis>
218 Use BitBake to build the extensible SDK specifically for
219 the Minnowboard:
220 <literallayout class='monospaced'>
221 $ cd ~/poky/build
222 $ bitbake core-image-minimal -c populate_sdk_ext
223 </literallayout>
224 Once the build finishes, you can find the SDK installer
225 file (i.e. <filename>*.sh</filename> file) in the
226 following directory:
227 <literallayout class='monospaced'>
228 ~/poky/build/tmp/deploy/sdk
229 </literallayout>
230 For this example, the installer file is named
231 <filename>poky-glibc-x86_64-core-image-minimal-i586-toolchain-ext-&DISTRO;.sh</filename>
232 </para></listitem>
233 <listitem><para>
234 <emphasis>Install the Extensible SDK:</emphasis>
235 Use the following command to install the SDK.
236 For this example, install the SDK in the default
237 <filename>~/poky_sdk</filename> directory:
238 <literallayout class='monospaced'>
239 $ cd ~/poky/build/tmp/deploy/sdk
240 $ ./poky-glibc-x86_64-core-image-minimal-i586-toolchain-ext-&DISTRO;.sh
241 Poky (Yocto Project Reference Distro) Extensible SDK installer version &DISTRO;
242 ============================================================================
243 Enter target directory for SDK (default: ~/poky_sdk):
244 You are about to install the SDK to "/home/scottrif/poky_sdk". Proceed[Y/n]? Y
245 Extracting SDK......................................done
246 Setting it up...
247 Extracting buildtools...
248 Preparing build system...
249 Parsing recipes: 100% |#################################################################| Time: 0:00:52
250 Initializing tasks: 100% |############## ###############################################| Time: 0:00:04
251 Checking sstate mirror object availability: 100% |######################################| Time: 0:00:00
252 Parsing recipes: 100% |#################################################################| Time: 0:00:33
253 Initializing tasks: 100% |##############################################################| Time: 0:00:00
254 done
255 SDK has been successfully set up and is ready to be used.
256 Each time you wish to use the SDK in a new shell session, you need to source the environment setup script e.g.
257 $ . /home/scottrif/poky_sdk/environment-setup-i586-poky-linux
258 </literallayout>
259 </para></listitem>
260 <listitem><para id='setting-up-the-esdk-terminal'>
261 <emphasis>Set Up a New Terminal to Work With the Extensible SDK:</emphasis>
262 You must set up a new terminal to work with the SDK.
263 You cannot use the same BitBake shell used to build the
264 installer.</para>
265
266 <para>After opening a new shell, run the SDK environment
267 setup script as directed by the output from installing
268 the SDK:
269 <literallayout class='monospaced'>
270 $ source ~/poky_sdk/environment-setup-i586-poky-linux
271 "SDK environment now set up; additionally you may now run devtool to perform development tasks.
272 Run devtool --help for further details.
273 </literallayout>
274 <note>
275 If you get a warning about attempting to use the
276 extensible SDK in an environment set up to run
277 BitBake, you did not use a new shell.
278 </note>
279 </para></listitem>
280 <listitem><para>
281 <emphasis>Build the Clean Image:</emphasis>
282 The final step in preparing to work on the kernel is to
283 build an initial image using <filename>devtool</filename>
284 in the new terminal you just set up and initialized for
285 SDK work:
286 <literallayout class='monospaced'>
287 $ devtool build-image
288 Parsing recipes: 100% |##########################################| Time: 0:00:05
289 Parsing of 830 .bb files complete (0 cached, 830 parsed). 1299 targets, 47 skipped, 0 masked, 0 errors.
290 WARNING: No packages to add, building image core-image-minimal unmodified
291 Loading cache: 100% |############################################| Time: 0:00:00
292 Loaded 1299 entries from dependency cache.
293 NOTE: Resolving any missing task queue dependencies
294 Initializing tasks: 100% |#######################################| Time: 0:00:07
295 Checking sstate mirror object availability: 100% |###############| Time: 0:00:00
296 NOTE: Executing SetScene Tasks
297 NOTE: Executing RunQueue Tasks
298 NOTE: Tasks Summary: Attempted 2866 tasks of which 2604 didn't need to be rerun and all succeeded.
299 NOTE: Successfully built core-image-minimal. You can find output files in /home/scottrif/poky_sdk/tmp/deploy/images/qemux86
300 </literallayout>
301 If you were building for actual hardware and not for
302 emulation, you could flash the image to a USB stick
303 on <filename>/dev/sdd</filename> and boot your device.
304 For an example that uses a Minnowboard, see the
305 <ulink url='https://wiki.yoctoproject.org/wiki/TipsAndTricks/KernelDevelopmentWithEsdk'>TipsAndTricks/KernelDevelopmentWithEsdk</ulink>
306 Wiki page.
307 </para></listitem>
308 </orderedlist>
309 </para>
310
311 <para>
312 At this point you have set up to start making modifications to the
313 kernel by using the extensible SDK.
314 For a continued example, see the
315 "<link linkend='using-devtool-to-patch-the-kernel'>Using <filename>devtool</filename> to Patch the Kernel</link>"
316 section.
317 </para>
318 </section>
319
320 <section id='getting-ready-for-traditional-kernel-development'>
321 <title>Getting Ready for Traditional Kernel Development</title>
322
323 <para>
324 For traditional kernel development using the Yocto
325 Project, you need to establish a local copy of the
326 kernel source.
327 You can find Git repositories of supported Yocto Project
328 kernels organized under "Yocto Linux Kernel" in the Yocto
329 Project Source Repositories at
330 <ulink url='&YOCTO_GIT_URL;/cgit.cgi'></ulink>.
331 </para>
332
333 <para>
334 For simplicity, it is recommended that you create your copy
335 of the kernel Git repository outside of the
336 <ulink url='&YOCTO_DOCS_REF_URL;source-directory'>Source Directory</ulink>,
337 which is usually named <filename>poky</filename>.
338 </para>
339
340 <para>
341 The following command shows how to create a local copy of the
342 <filename>linux-yocto-4.9</filename> kernel:
343 <literallayout class='monospaced'>
344 $ git clone git://git.yoctoproject.org/linux-yocto-4.9 linux-yocto-4.9.git
345 Cloning into 'linux-yocto-4.9.git'...
346 remote: Counting objects: 5094108, done.
347 remote: Compressing objects: 100% (765113/765113), done.
348 remote: Total 5094108 (delta 4294009), reused 5088388 (delta 4288312)
349 Receiving objects: 100% (5094108/5094108), 1.02 GiB | 7.82 MiB/s, done.
350 Resolving deltas: 100% (4294009/4294009), done.
351 Checking connectivity... done.
352 Checking out files: 100% (56233/56233), done.
353 </literallayout>
354 </para>
355 </section>
356</section> 136</section>
357 137
358<section id='kernel-modification-workflow'> 138<section id='kernel-modification-workflow'>
@@ -370,21 +150,8 @@
370 <para> 150 <para>
371 This section presents a high-level overview of the Yocto Project 151 This section presents a high-level overview of the Yocto Project
372 kernel modification workflow. 152 kernel modification workflow.
373 You can find additional information here: 153 The illustration and accompanying list provide general information
374 <itemizedlist> 154 and references for further information.
375 <listitem><para>
376 The
377 "<link linkend='using-devtool-to-patch-the-kernel'>Using <filename>devtool</filename> to Patch the Kernel</link>"
378 section.
379 </para></listitem>
380 <listitem><para>
381 The
382 "<ulink url='&YOCTO_DOCS_DEV_URL;#configuring-the-kernel'>Configuring the Kernel</ulink>"
383 section in the Yocto Project Development Manual.
384 </para></listitem>
385 </itemizedlist>
386 This illustration and the following list summarizes the kernel
387 modification general workflow.
388 <imagedata fileref="figures/kernel-dev-flow.png" 155 <imagedata fileref="figures/kernel-dev-flow.png"
389 width="9in" depth="5in" align="center" scalefit="1" /> 156 width="9in" depth="5in" align="center" scalefit="1" />
390 </para> 157 </para>
@@ -392,58 +159,57 @@
392 <para> 159 <para>
393 <orderedlist> 160 <orderedlist>
394 <listitem><para> 161 <listitem><para>
395 <emphasis>Set up Your Host Development System to Support 162 <emphasis>Set Up Your Host Development System to Support
396 Development Using the Yocto Project</emphasis>: 163 Development Using the Yocto Project:</emphasis>
397 See the 164 See the
398 "<ulink url='&YOCTO_DOCS_QS_URL;#yp-resources'>Setting Up to Use the Yocto Project</ulink>" 165 "<ulink url='&YOCTO_DOCS_QS_URL;#yp-resources'>Setting Up to Use the Yocto Project</ulink>"
399 section in the Yocto Project Quick Start for options on how 166 section in the Yocto Project Quick Start for options on how
400 to get a build host ready to use the Yocto Project. 167 to get a build host ready to use the Yocto Project.
401 </para></listitem> 168 </para></listitem>
402 <listitem><para> 169 <listitem><para>
403 <emphasis>Establish the Temporary Kernel Source Files</emphasis>: 170 <emphasis>Set Up Your Host Development System for Kernel Development:</emphasis>
404 Temporary kernel source files are kept in the 171 It is recommended that you use <filename>devtool</filename>
405 <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink> 172 and an extensible SDK for kernel development.
406 created by the OpenEmbedded build system when you run BitBake. 173 Alternatively, you can use traditional kernel development
407 If you have never built the kernel in which you are 174 methods with the Yocto Project.
408 interested, you need to run an initial build to 175 Either way, there are steps you need to take to get the
409 establish local kernel source files.</para> 176 development environment ready.</para>
410 177
411 <para>If you are building an image for the first time, you 178 <para>Using <filename>devtool</filename> and the eSDK requires
412 need to get the build environment ready by sourcing an 179 that you have a clean build of the image and that you are
413 environment setup script 180 set up with the appropriate eSDK.
414 (i.e. <filename>oe-init-build-env</filename> or 181 For more information, see the
415 <filename>oe-init-build-env-memres</filename>). 182 "<link linkend='getting-ready-to-develop-using-devtool'>Getting Ready to Develop Using <filename>devtool</filename></link>"
416 You also need to be sure two key configuration files 183 section.</para>
417 (<filename>local.conf</filename> and 184
418 <filename>bblayers.conf</filename>) are configured 185 <para>Using traditional kernel development requires that you
419 appropriately.</para> 186 have the kernel source available in an isolated local Git
420 187 repository.
421 <para>The entire process for building an image is overviewed 188 For more information, see the
422 in the 189 "<link linkend='getting-ready-for-traditional-kernel-development'>Getting Ready for Traditional Kernel Development</link>"
423 "<ulink url='&YOCTO_DOCS_QS_URL;#qs-building-images'>Building Images</ulink>" 190 section.
424 section of the Yocto Project Quick Start.
425 You might want to reference this information.
426 You can find more information on BitBake in the
427 <ulink url='&YOCTO_DOCS_BB_URL;'>BitBake User Manual</ulink>.
428 </para>
429
430 <para>The build process supports several types of images to
431 satisfy different needs.
432 See the "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>"
433 chapter in the Yocto Project Reference Manual for information
434 on supported images.
435 </para></listitem> 191 </para></listitem>
436 <listitem><para> 192 <listitem><para>
437 <emphasis>Make Changes to the Kernel Source Code if 193 <emphasis>Make Changes to the Kernel Source Code if
438 applicable</emphasis>: 194 applicable:</emphasis>
439 Modifying the kernel does not always mean directly 195 Modifying the kernel does not always mean directly
440 changing source files. 196 changing source files.
441 However, if you have to do this, you make the changes to the 197 However, if you have to do this, you make the changes to the
442 files in the Build Directory. 198 files in the eSDK's Build Directory if you are using
199 <filename>devtool</filename>.
200 For more information, see the
201 "<link linkend='using-devtool-to-patch-the-kernel'>Using <filename>devtool</filename> to Patch the Kernel</link>"
202 section.</para>
203
204 <para>If you are using traditional kernel development, you
205 edit the source files in the kernel's local Git repository.
206 For more information, see the
207 "<link linkend='using-traditional-kernel-development-to-patch-the-kernel'>Using Traditional Kernel Development to Patch the Kernel</link>"
208 section.
443 </para></listitem> 209 </para></listitem>
444 <listitem><para> 210 <listitem><para>
445 <emphasis>Make Kernel Configuration Changes if 211 <emphasis>Make Kernel Configuration Changes if
446 Applicable</emphasis>: 212 Applicable:</emphasis>
447 If your situation calls for changing the kernel's 213 If your situation calls for changing the kernel's
448 configuration, you can use 214 configuration, you can use
449 <link linkend='generating-configuration-files'><filename>menuconfig</filename></link>, 215 <link linkend='generating-configuration-files'><filename>menuconfig</filename></link>,
@@ -455,10 +221,7 @@
455 Try to resist the temptation to directly edit an 221 Try to resist the temptation to directly edit an
456 existing <filename>.config</filename> file, which is 222 existing <filename>.config</filename> file, which is
457 found in the Build Directory among the source code 223 found in the Build Directory among the source code
458 used for the build (e.g. see the workflow illustration 224 used for the build.
459 in the
460 "<link linkend='kernel-modification-workflow'>Kernel Modification Workflow</link>"
461 section).
462 Doing so, can produce unexpected results when the 225 Doing so, can produce unexpected results when the
463 OpenEmbedded build system regenerates the configuration 226 OpenEmbedded build system regenerates the configuration
464 file. 227 file.
@@ -481,61 +244,15 @@
481 you interactively set up kernel configurations. 244 you interactively set up kernel configurations.
482 </para></listitem> 245 </para></listitem>
483 <listitem><para> 246 <listitem><para>
484 <emphasis>Rebuild the Kernel Image With Your Changes</emphasis>: 247 <emphasis>Rebuild the Kernel Image With Your Changes:</emphasis>
485 Rebuilding the kernel image applies your changes. 248 Rebuilding the kernel image applies your changes.
249 Depending on your target hardware, you can verify your changes
250 on actual hardware or perhaps QEMU.
486 </para></listitem> 251 </para></listitem>
487 </orderedlist> 252 </orderedlist>
488 </para> 253 </para>
489</section> 254</section>
490 255
491<section id='kernel-dev-other-resources'>
492 <title>Other Resources</title>
493
494 <para>
495 The remainder of this manual provides instructions for completing
496 specific Linux kernel development tasks.
497 These instructions assume you are comfortable working with
498 <ulink url='http://openembedded.org/wiki/Bitbake'>BitBake</ulink>
499 recipes and basic open-source development tools.
500 Understanding these concepts will facilitate the process of working
501 with the kernel recipes.
502 If you find you need some additional background, please be sure to
503 review and understand the following documentation:
504 <itemizedlist>
505 <listitem><para>
506 <ulink url='&YOCTO_DOCS_QS_URL;'>Yocto Project Quick Start</ulink>
507 </para></listitem>
508 <listitem><para>
509 <ulink url='&YOCTO_DOCS_SDK_URL;#using-devtool-in-your-sdk-workflow'><filename>devtool</filename> workflow</ulink>
510 as described in the Yocto Project Software Development Kit
511 (SDK) Developer's Guide.
512 </para></listitem>
513 <listitem><para>
514 The
515 "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>" section
516 in the Yocto Project Development Manual
517 </para></listitem>
518 <listitem><para>
519 The
520 "<link linkend='kernel-modification-workflow'>Kernel Modification Workflow</link>"
521 section.
522 </para></listitem>
523 </itemizedlist>
524 </para>
525
526 <para>
527 Finally, while this document focuses on the manual creation of
528 recipes, patches, and configuration files, the Yocto Project
529 Board Support Package (BSP) tools are available to automate
530 this process with existing content and work well to create the
531 initial framework and boilerplate code.
532 For details on these tools, see the
533 "<ulink url='&YOCTO_DOCS_BSP_URL;#using-the-yocto-projects-bsp-tools'>Using the Yocto Project's BSP Tools</ulink>"
534 section in the Yocto Project Board Support Package (BSP) Developer's
535 Guide.
536 </para>
537</section>
538
539</chapter> 256</chapter>
540<!-- 257<!--
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