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Patrick Williamsc124f4f2015-09-15 14:41:29 -05001<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
2 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
3
4<chapter id="bitbake-user-manual-intro">
5 <title>Overview</title>
6
7 <para>
8 Welcome to the BitBake User Manual.
9 This manual provides information on the BitBake tool.
10 The information attempts to be as independent as possible regarding
11 systems that use BitBake, such as OpenEmbedded and the
12 Yocto Project.
13 In some cases, scenarios or examples within the context of
14 a build system are used in the manual to help with understanding.
15 For these cases, the manual clearly states the context.
16 </para>
17
18 <section id="intro">
19 <title>Introduction</title>
20
21 <para>
22 Fundamentally, BitBake is a generic task execution
23 engine that allows shell and Python tasks to be run
24 efficiently and in parallel while working within
25 complex inter-task dependency constraints.
26 One of BitBake's main users, OpenEmbedded, takes this core
27 and builds embedded Linux software stacks using
28 a task-oriented approach.
29 </para>
30
31 <para>
32 Conceptually, BitBake is similar to GNU Make in
33 some regards but has significant differences:
34 <itemizedlist>
35 <listitem><para>
36 BitBake executes tasks according to provided
37 metadata that builds up the tasks.
38 Metadata is stored in recipe (<filename>.bb</filename>)
39 and related recipe "append" (<filename>.bbappend</filename>)
40 files, configuration (<filename>.conf</filename>) and
41 underlying include (<filename>.inc</filename>) files, and
42 in class (<filename>.bbclass</filename>) files.
43 The metadata provides
44 BitBake with instructions on what tasks to run and
45 the dependencies between those tasks.
46 </para></listitem>
47 <listitem><para>
48 BitBake includes a fetcher library for obtaining source
49 code from various places such as local files, source control
50 systems, or websites.
51 </para></listitem>
52 <listitem><para>
53 The instructions for each unit to be built (e.g. a piece
54 of software) are known as "recipe" files and
55 contain all the information about the unit
56 (dependencies, source file locations, checksums, description
57 and so on).
58 </para></listitem>
59 <listitem><para>
60 BitBake includes a client/server abstraction and can
61 be used from a command line or used as a service over
62 XML-RPC and has several different user interfaces.
63 </para></listitem>
64 </itemizedlist>
65 </para>
66 </section>
67
68 <section id="history-and-goals">
69 <title>History and Goals</title>
70
71 <para>
72 BitBake was originally a part of the OpenEmbedded project.
73 It was inspired by the Portage package management system
74 used by the Gentoo Linux distribution.
75 On December 7, 2004, OpenEmbedded project team member
76 Chris Larson split the project into two distinct pieces:
77 <itemizedlist>
78 <listitem><para>BitBake, a generic task executor</para></listitem>
79 <listitem><para>OpenEmbedded, a metadata set utilized by
80 BitBake</para></listitem>
81 </itemizedlist>
82 Today, BitBake is the primary basis of the
83 <ulink url="http://www.openembedded.org/">OpenEmbedded</ulink>
84 project, which is being used to build and maintain Linux
85 distributions such as the
86 <ulink url='http://www.angstrom-distribution.org/'>Angstrom Distribution</ulink>,
87 and which is also being used as the build tool for Linux projects
88 such as the
89 <ulink url='http://www.yoctoproject.org'>Yocto Project</ulink>.
90 </para>
91
92 <para>
93 Prior to BitBake, no other build tool adequately met the needs of
94 an aspiring embedded Linux distribution.
95 All of the build systems used by traditional desktop Linux
96 distributions lacked important functionality, and none of the
97 ad hoc Buildroot-based systems, prevalent in the
98 embedded space, were scalable or maintainable.
99 </para>
100
101 <para>
102 Some important original goals for BitBake were:
103 <itemizedlist>
104 <listitem><para>
105 Handle cross-compilation.
106 </para></listitem>
107 <listitem><para>
108 Handle inter-package dependencies (build time on
109 target architecture, build time on native
110 architecture, and runtime).
111 </para></listitem>
112 <listitem><para>
113 Support running any number of tasks within a given
114 package, including, but not limited to, fetching
115 upstream sources, unpacking them, patching them,
116 configuring them, and so forth.
117 </para></listitem>
118 <listitem><para>
119 Be Linux distribution agnostic for both build and
120 target systems.
121 </para></listitem>
122 <listitem><para>
123 Be architecture agnostic.
124 </para></listitem>
125 <listitem><para>
126 Support multiple build and target operating systems
127 (e.g. Cygwin, the BSDs, and so forth).
128 </para></listitem>
129 <listitem><para>
130 Be self contained, rather than tightly
131 integrated into the build machine's root
132 filesystem.
133 </para></listitem>
134 <listitem><para>
135 Handle conditional metadata on the target architecture,
136 operating system, distribution, and machine.
137 </para></listitem>
138 <listitem><para>
139 Be easy to use the tools to supply local metadata and packages
140 against which to operate.
141 </para></listitem>
142 <listitem><para>
143 Be easy to use BitBake to collaborate between multiple
144 projects for their builds.
145 </para></listitem>
146 <listitem><para>
147 Provide an inheritance mechanism to share
148 common metadata between many packages.
149 </para></listitem>
150 </itemizedlist>
151 Over time it became apparent that some further requirements
152 were necessary:
153 <itemizedlist>
154 <listitem><para>
155 Handle variants of a base recipe (e.g. native, sdk,
156 and multilib).
157 </para></listitem>
158 <listitem><para>
159 Split metadata into layers and allow layers
160 to enhance or override other layers.
161 </para></listitem>
162 <listitem><para>
163 Allow representation of a given set of input variables
164 to a task as a checksum.
165 Based on that checksum, allow acceleration of builds
166 with prebuilt components.
167 </para></listitem>
168 </itemizedlist>
169 BitBake satisfies all the original requirements and many more
170 with extensions being made to the basic functionality to
171 reflect the additional requirements.
172 Flexibility and power have always been the priorities.
173 BitBake is highly extensible and supports embedded Python code and
174 execution of any arbitrary tasks.
175 </para>
176 </section>
177
178 <section id="Concepts">
179 <title>Concepts</title>
180
181 <para>
182 BitBake is a program written in the Python language.
183 At the highest level, BitBake interprets metadata, decides
184 what tasks are required to run, and executes those tasks.
185 Similar to GNU Make, BitBake controls how software is
186 built.
187 GNU Make achieves its control through "makefiles", while
188 BitBake uses "recipes".
189 </para>
190
191 <para>
192 BitBake extends the capabilities of a simple
193 tool like GNU Make by allowing for the definition of much more
194 complex tasks, such as assembling entire embedded Linux
195 distributions.
196 </para>
197
198 <para>
199 The remainder of this section introduces several concepts
200 that should be understood in order to better leverage
201 the power of BitBake.
202 </para>
203
204 <section id='recipes'>
205 <title>Recipes</title>
206
207 <para>
208 BitBake Recipes, which are denoted by the file extension
209 <filename>.bb</filename>, are the most basic metadata files.
210 These recipe files provide BitBake with the following:
211 <itemizedlist>
212 <listitem><para>Descriptive information about the
213 package (author, homepage, license, and so on)</para></listitem>
214 <listitem><para>The version of the recipe</para></listitem>
215 <listitem><para>Existing dependencies (both build
216 and runtime dependencies)</para></listitem>
217 <listitem><para>Where the source code resides and
218 how to fetch it</para></listitem>
219 <listitem><para>Whether the source code requires
220 any patches, where to find them, and how to apply
221 them</para></listitem>
222 <listitem><para>How to configure and compile the
223 source code</para></listitem>
224 <listitem><para>Where on the target machine to install the
225 package or packages created</para></listitem>
226 </itemizedlist>
227 </para>
228
229 <para>
230 Within the context of BitBake, or any project utilizing BitBake
231 as its build system, files with the <filename>.bb</filename>
232 extension are referred to as recipes.
233 <note>
234 The term "package" is also commonly used to describe recipes.
235 However, since the same word is used to describe packaged
236 output from a project, it is best to maintain a single
237 descriptive term - "recipes".
238 Put another way, a single "recipe" file is quite capable
239 of generating a number of related but separately installable
240 "packages".
241 In fact, that ability is fairly common.
242 </note>
243 </para>
244 </section>
245
246 <section id='configuration-files'>
247 <title>Configuration Files</title>
248
249 <para>
250 Configuration files, which are denoted by the
251 <filename>.conf</filename> extension, define
252 various configuration variables that govern the project's build
253 process.
254 These files fall into several areas that define
255 machine configuration options, distribution configuration
256 options, compiler tuning options, general common
257 configuration options, and user configuration options.
258 The main configuration file is the sample
259 <filename>bitbake.conf</filename> file, which is
260 located within the BitBake source tree
261 <filename>conf</filename> directory.
262 </para>
263 </section>
264
265 <section id='classes'>
266 <title>Classes</title>
267
268 <para>
269 Class files, which are denoted by the
270 <filename>.bbclass</filename> extension, contain
271 information that is useful to share between metadata files.
272 The BitBake source tree currently comes with one class metadata file
273 called <filename>base.bbclass</filename>.
274 You can find this file in the
275 <filename>classes</filename> directory.
276 The <filename>base.bbclass</filename> class files is special since it
277 is always included automatically for all recipes
278 and classes.
279 This class contains definitions for standard basic tasks such
280 as fetching, unpacking, configuring (empty by default),
281 compiling (runs any Makefile present), installing (empty by
282 default) and packaging (empty by default).
283 These tasks are often overridden or extended by other classes
284 added during the project development process.
285 </para>
286 </section>
287
288 <section id='layers'>
289 <title>Layers</title>
290
291 <para>
292 Layers allow you to isolate different types of
293 customizations from each other.
294 While you might find it tempting to keep everything in one layer
295 when working on a single project, the more modular you organize
296 your metadata, the easier it is to cope with future changes.
297 </para>
298
299 <para>
300 To illustrate how you can use layers to keep things modular,
301 consider customizations you might make to support a specific target machine.
302 These types of customizations typically reside in a special layer,
303 rather than a general layer, called a Board Support Package (BSP)
304 Layer.
305 Furthermore, the machine customizations should be isolated from
306 recipes and metadata that support a new GUI environment, for
307 example.
308 This situation gives you a couple of layers: one for the machine
309 configurations and one for the GUI environment.
310 It is important to understand, however, that the BSP layer can still
311 make machine-specific additions to recipes within
312 the GUI environment layer without polluting the GUI layer itself
313 with those machine-specific changes.
314 You can accomplish this through a recipe that is a BitBake append
315 (<filename>.bbappend</filename>) file.
316 </para>
317 </section>
318
319 <section id='append-bbappend-files'>
320 <title>Append Files</title>
321
322 <para>
323 Append files, which are files that have the
324 <filename>.bbappend</filename> file extension, extend or
325 override information in an existing recipe file.
326 </para>
327
328 <para>
329 BitBake expects every append file to have a corresponding recipe file.
330 Furthermore, the append file and corresponding recipe file
331 must use the same root filename.
332 The filenames can differ only in the file type suffix used
333 (e.g. <filename>formfactor_0.0.bb</filename> and
334 <filename>formfactor_0.0.bbappend</filename>).
335 </para>
336
337 <para>
338 Information in append files extends or
339 overrides the information in the underlying,
340 similarly-named recipe files.
341 </para>
342
343 <para>
344 When you name an append file, you can use the
345 wildcard character (%) to allow for matching recipe names.
346 For example, suppose you have an append file named
347 as follows:
348 <literallayout class='monospaced'>
349 busybox_1.21.%.bbappend
350 </literallayout>
351 That append file would match any <filename>busybox_1.21.x.bb</filename>
352 version of the recipe.
353 So, the append file would match the following recipe names:
354 <literallayout class='monospaced'>
355 busybox_1.21.1.bb
356 busybox_1.21.2.bb
357 busybox_1.21.3.bb
358 </literallayout>
359 If the <filename>busybox</filename> recipe was updated to
360 <filename>busybox_1.3.0.bb</filename>, the append name would not
361 match.
362 However, if you named the append file
363 <filename>busybox_1.%.bbappend</filename>, then you would have a match.
364 </para>
365
366 <para>
367 In the most general case, you could name the append file something as
368 simple as <filename>busybox_%.bbappend</filename> to be entirely
369 version independent.
370 </para>
371 </section>
372 </section>
373
374 <section id='obtaining-bitbake'>
375 <title>Obtaining BitBake</title>
376
377 <para>
378 You can obtain BitBake several different ways:
379 <itemizedlist>
380 <listitem><para><emphasis>Cloning BitBake:</emphasis>
381 Using Git to clone the BitBake source code repository
382 is the recommended method for obtaining BitBake.
383 Cloning the repository makes it easy to get bug fixes
384 and have access to stable branches and the master
385 branch.
386 Once you have cloned BitBake, you should use
387 the latest stable
388 branch for development since the master branch is for
389 BitBake development and might contain less stable changes.
390 </para>
391 <para>You usually need a version of BitBake
392 that matches the metadata you are using.
393 The metadata is generally backwards compatible but
394 not forward compatible.</para>
395 <para>Here is an example that clones the BitBake repository:
396 <literallayout class='monospaced'>
397 $ git clone git://git.openembedded.org/bitbake
398 </literallayout>
399 This command clones the BitBake Git repository into a
400 directory called <filename>bitbake</filename>.
401 Alternatively, you can
402 designate a directory after the
403 <filename>git clone</filename> command
404 if you want to call the new directory something
405 other than <filename>bitbake</filename>.
406 Here is an example that names the directory
407 <filename>bbdev</filename>:
408 <literallayout class='monospaced'>
409 $ git clone git://git.openembedded.org/bitbake bbdev
410 </literallayout></para></listitem>
411 <listitem><para><emphasis>Installation using your Distribution
412 Package Management System:</emphasis>
413 This method is not
414 recommended because the BitBake version that is
415 provided by your distribution, in most cases,
416 is several
417 releases behind a snapshot of the BitBake repository.
418 </para></listitem>
419 <listitem><para><emphasis>Taking a snapshot of BitBake:</emphasis>
420 Downloading a snapshot of BitBake from the
421 source code repository gives you access to a known
422 branch or release of BitBake.
423 <note>
424 Cloning the Git repository, as described earlier,
425 is the preferred method for getting BitBake.
426 Cloning the repository makes it easier to update as
427 patches are added to the stable branches.
428 </note></para>
429 <para>The following example downloads a snapshot of
430 BitBake version 1.17.0:
431 <literallayout class='monospaced'>
432 $ wget http://git.openembedded.org/bitbake/snapshot/bitbake-1.17.0.tar.gz
433 $ tar zxpvf bitbake-1.17.0.tar.gz
434 </literallayout>
435 After extraction of the tarball using the tar utility,
436 you have a directory entitled
437 <filename>bitbake-1.17.0</filename>.
438 </para></listitem>
439 <listitem><para><emphasis>Using the BitBake that Comes With Your
440 Build Checkout:</emphasis>
441 A final possibility for getting a copy of BitBake is that it
442 already comes with your checkout of a larger Bitbake-based build
443 system, such as Poky or Yocto Project.
444 Rather than manually checking out individual layers and
445 gluing them together yourself, you can check
446 out an entire build system.
447 The checkout will already include a version of BitBake that
448 has been thoroughly tested for compatibility with the other
449 components.
450 For information on how to check out a particular BitBake-based
451 build system, consult that build system's supporting documentation.
452 </para></listitem>
453 </itemizedlist>
454 </para>
455 </section>
456
457 <section id="bitbake-user-manual-command">
458 <title>The BitBake Command</title>
459
460 <para>
461 The <filename>bitbake</filename> command is the primary interface
462 to the BitBake tool.
463 This section presents the BitBake command syntax and provides
464 several execution examples.
465 </para>
466
467 <section id='usage-and-syntax'>
468 <title>Usage and syntax</title>
469
470 <para>
471 Following is the usage and syntax for BitBake:
472 <literallayout class='monospaced'>
473 $ bitbake -h
Patrick Williamsd8c66bc2016-06-20 12:57:21 -0500474 Usage: bitbake [options] [recipename/target recipe:do_task ...]
Patrick Williamsc124f4f2015-09-15 14:41:29 -0500475
476 Executes the specified task (default is 'build') for a given set of target recipes (.bb files).
477 It is assumed there is a conf/bblayers.conf available in cwd or in BBPATH which
478 will provide the layer, BBFILES and other configuration information.
479
480 Options:
481 --version show program's version number and exit
482 -h, --help show this help message and exit
483 -b BUILDFILE, --buildfile=BUILDFILE
484 Execute tasks from a specific .bb recipe directly.
485 WARNING: Does not handle any dependencies from other
486 recipes.
487 -k, --continue Continue as much as possible after an error. While the
488 target that failed and anything depending on it cannot
489 be built, as much as possible will be built before
490 stopping.
491 -a, --tryaltconfigs Continue with builds by trying to use alternative
492 providers where possible.
493 -f, --force Force the specified targets/task to run (invalidating
494 any existing stamp file).
495 -c CMD, --cmd=CMD Specify the task to execute. The exact options
496 available depend on the metadata. Some examples might
497 be 'compile' or 'populate_sysroot' or 'listtasks' may
498 give a list of the tasks available.
499 -C INVALIDATE_STAMP, --clear-stamp=INVALIDATE_STAMP
500 Invalidate the stamp for the specified task such as
501 'compile' and then run the default task for the
502 specified target(s).
503 -r PREFILE, --read=PREFILE
504 Read the specified file before bitbake.conf.
505 -R POSTFILE, --postread=POSTFILE
506 Read the specified file after bitbake.conf.
507 -v, --verbose Output more log message data to the terminal.
508 -D, --debug Increase the debug level. You can specify this more
509 than once.
510 -n, --dry-run Don't execute, just go through the motions.
511 -S SIGNATURE_HANDLER, --dump-signatures=SIGNATURE_HANDLER
512 Dump out the signature construction information, with
513 no task execution. The SIGNATURE_HANDLER parameter is
514 passed to the handler. Two common values are none and
515 printdiff but the handler may define more/less. none
516 means only dump the signature, printdiff means compare
517 the dumped signature with the cached one.
518 -p, --parse-only Quit after parsing the BB recipes.
519 -s, --show-versions Show current and preferred versions of all recipes.
520 -e, --environment Show the global or per-recipe environment complete
521 with information about where variables were
522 set/changed.
523 -g, --graphviz Save dependency tree information for the specified
524 targets in the dot syntax.
525 -I EXTRA_ASSUME_PROVIDED, --ignore-deps=EXTRA_ASSUME_PROVIDED
526 Assume these dependencies don't exist and are already
527 provided (equivalent to ASSUME_PROVIDED). Useful to
528 make dependency graphs more appealing
529 -l DEBUG_DOMAINS, --log-domains=DEBUG_DOMAINS
530 Show debug logging for the specified logging domains
531 -P, --profile Profile the command and save reports.
Patrick Williamsd8c66bc2016-06-20 12:57:21 -0500532 -u UI, --ui=UI The user interface to use (depexp, goggle, hob, knotty
533 or ncurses - default knotty).
Patrick Williamsc124f4f2015-09-15 14:41:29 -0500534 -t SERVERTYPE, --servertype=SERVERTYPE
Patrick Williamsd8c66bc2016-06-20 12:57:21 -0500535 Choose which server type to use (process or xmlrpc -
536 default process).
Patrick Williamsc124f4f2015-09-15 14:41:29 -0500537 --token=XMLRPCTOKEN Specify the connection token to be used when
538 connecting to a remote server.
539 --revisions-changed Set the exit code depending on whether upstream
540 floating revisions have changed or not.
541 --server-only Run bitbake without a UI, only starting a server
542 (cooker) process.
543 -B BIND, --bind=BIND The name/address for the bitbake server to bind to.
544 --no-setscene Do not run any setscene tasks. sstate will be ignored
545 and everything needed, built.
546 --remote-server=REMOTE_SERVER
547 Connect to the specified server.
548 -m, --kill-server Terminate the remote server.
549 --observe-only Connect to a server as an observing-only client.
550 --status-only Check the status of the remote bitbake server.
Patrick Williamsd8c66bc2016-06-20 12:57:21 -0500551 -w WRITEEVENTLOG, --write-log=WRITEEVENTLOG
552 Writes the event log of the build to a bitbake event
553 json file. Use '' (empty string) to assign the name
554 automatically.
Patrick Williamsc124f4f2015-09-15 14:41:29 -0500555 </literallayout>
556 </para>
557 </section>
558
559 <section id='bitbake-examples'>
560 <title>Examples</title>
561
562 <para>
563 This section presents some examples showing how to use BitBake.
564 </para>
565
566 <section id='example-executing-a-task-against-a-single-recipe'>
567 <title>Executing a Task Against a Single Recipe</title>
568
569 <para>
570 Executing tasks for a single recipe file is relatively simple.
571 You specify the file in question, and BitBake parses
572 it and executes the specified task.
573 If you do not specify a task, BitBake executes the default
574 task, which is "build”.
575 BitBake obeys inter-task dependencies when doing
576 so.
577 </para>
578
579 <para>
580 The following command runs the build task, which is
581 the default task, on the <filename>foo_1.0.bb</filename>
582 recipe file:
583 <literallayout class='monospaced'>
584 $ bitbake -b foo_1.0.bb
585 </literallayout>
586 The following command runs the clean task on the
587 <filename>foo.bb</filename> recipe file:
588 <literallayout class='monospaced'>
589 $ bitbake -b foo.bb -c clean
590 </literallayout>
591 <note>
592 The "-b" option explicitly does not handle recipe
593 dependencies.
594 Other than for debugging purposes, it is instead
595 recommended that you use the syntax presented in the
596 next section.
597 </note>
598 </para>
599 </section>
600
601 <section id='executing-tasks-against-a-set-of-recipe-files'>
602 <title>Executing Tasks Against a Set of Recipe Files</title>
603
604 <para>
605 There are a number of additional complexities introduced
606 when one wants to manage multiple <filename>.bb</filename>
607 files.
608 Clearly there needs to be a way to tell BitBake what
609 files are available and, of those, which you
610 want to execute.
611 There also needs to be a way for each recipe
612 to express its dependencies, both for build-time and
613 runtime.
614 There must be a way for you to express recipe preferences
615 when multiple recipes provide the same functionality, or when
616 there are multiple versions of a recipe.
617 </para>
618
619 <para>
620 The <filename>bitbake</filename> command, when not using
621 "--buildfile" or "-b" only accepts a "PROVIDES".
622 You cannot provide anything else.
623 By default, a recipe file generally "PROVIDES" its
624 "packagename" as shown in the following example:
625 <literallayout class='monospaced'>
626 $ bitbake foo
627 </literallayout>
628 This next example "PROVIDES" the package name and also uses
629 the "-c" option to tell BitBake to just execute the
630 <filename>do_clean</filename> task:
631 <literallayout class='monospaced'>
632 $ bitbake -c clean foo
633 </literallayout>
634 </para>
635 </section>
636
637 <section id='generating-dependency-graphs'>
638 <title>Generating Dependency Graphs</title>
639
640 <para>
641 BitBake is able to generate dependency graphs using
642 the <filename>dot</filename> syntax.
643 You can convert these graphs into images using the
644 <filename>dot</filename> tool from
645 <ulink url='http://www.graphviz.org'>Graphviz</ulink>.
646 </para>
647
648 <para>
649 When you generate a dependency graph, BitBake writes four files
650 to the current working directory:
651 <itemizedlist>
652 <listitem><para><emphasis><filename>package-depends.dot</filename>:</emphasis>
653 Shows BitBake's knowledge of dependencies between
654 runtime targets.
655 </para></listitem>
656 <listitem><para><emphasis><filename>pn-depends.dot</filename>:</emphasis>
657 Shows dependencies between build-time targets
658 (i.e. recipes).
659 </para></listitem>
660 <listitem><para><emphasis><filename>task-depends.dot</filename>:</emphasis>
661 Shows dependencies between tasks.
662 </para></listitem>
663 <listitem><para><emphasis><filename>pn-buildlist</filename>:</emphasis>
664 Shows a simple list of targets that are to be built.
665 </para></listitem>
666 </itemizedlist>
667 </para>
668
669 <para>
670 To stop depending on common depends, use the "-I" depend
671 option and BitBake omits them from the graph.
672 Leaving this information out can produce more readable graphs.
673 This way, you can remove from the graph
674 <filename>DEPENDS</filename> from inherited classes
675 such as <filename>base.bbclass</filename>.
676 </para>
677
678 <para>
679 Here are two examples that create dependency graphs.
680 The second example omits depends common in OpenEmbedded from
681 the graph:
682 <literallayout class='monospaced'>
683 $ bitbake -g foo
684
685 $ bitbake -g -I virtual/kernel -I eglibc foo
686 </literallayout>
687 </para>
688 </section>
689 </section>
690 </section>
691</chapter>