summaryrefslogtreecommitdiffstats
path: root/documentation/dev-manual/dev-manual-start.xml
blob: 356abdf0a88fc84696be5f9f9ef9b0bc2ed48451 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >

<chapter id='dev-manual-start'>

<title>Getting Started with the Yocto Project</title>

<para>
    This chapter provides procedures related to getting set up to use the
    Yocto Project, working with Yocto Project source files, and building
    an image.
</para>

<section id='setting-up-the-development-host-to-use-the-yocto-project'>
    <title>Setting Up the Development Host to Use the Yocto Project</title>

    <para>
        This section provides procedures to set up your development host to
        use the Yocto Project.
        You can use the Yocto Project on a native Linux development host or
        you can use
        <ulink url='https://git.yoctoproject.org/cgit/cgit.cgi/crops/about/'>CROPS</ulink>,
        which leverages
        <ulink url='https://www.docker.com/'>Docker Containers</ulink>,
        to prepare any Linux, Mac, or Windows development host.
    </para>

    <para>
        Once your development host is set up to use the Yocto Project,
        further steps are necessary depending on what you want to
        accomplish.
        See the following references for information on how to prepare for
        Board Support Package (BSP) development, kernel development, and
        development using the <trademark class='trade'>Eclipse</trademark> IDE:
        <itemizedlist>
            <listitem><para>
                <emphasis>BSP Development:</emphasis>
                See the
                "<ulink url='&YOCTO_DOCS_BSP_URL;#preparing-your-build-host-to-work-with-bsp-layers'>Preparing Your Build Host to Work With BSP Layers</ulink>"
                section in the Yocto Project Board Support Package (BSP)
                Developer's Guide.
                </para></listitem>
            <listitem><para>
                <emphasis>Kernel Development:</emphasis>
                See the
                "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#preparing-the-build-host-to-work-on-the-kernel'>Preparing the Build Host to Work on the Kernel</ulink>"
                section in the Yocto Project Linux Kernel Development Manual.
                </para></listitem>
            <listitem><para>
                <emphasis>Eclipse Development:</emphasis>
                See the
                "<ulink url='&YOCTO_DOCS_SDK_URL;#sdk-eclipse-project'>Developing Applications Using <trademark class='trade'>Eclipse</trademark></ulink>"
                Chapter in the Yocto Project Application Development and the
                Extensible Software Development Kit (eSDK) manual.
                </para></listitem>
        </itemizedlist>
    </para>

    <section id='setting-up-a-native-linux-host'>
        <title>Setting Up a Native Linux Host</title>

        <para>
            Follow these steps to prepare a native Linux machine as your
            Yocto Project development host:
            <orderedlist>
                <listitem><para>
                    <emphasis>Use a Supported Linux Distribution:</emphasis>
                    You should have a reasonably current Linux-based host
                    system.
                    You will have the best results with a recent release of
                    Fedora, openSUSE, Debian, Ubuntu, or CentOS as these
                    releases are frequently tested against the Yocto Project
                    and officially supported.
                    For a list of the distributions under validation and their
                    status, see the
                    "<ulink url='&YOCTO_DOCS_REF_URL;#detailed-supported-distros'>Supported Linux Distributions</ulink>" section
                    in the Yocto Project Reference Manual and the wiki page at
                    <ulink url='&YOCTO_WIKI_URL;/wiki/Distribution_Support'>Distribution Support</ulink>.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Have Enough Free Memory:</emphasis>
                    You should have at least 50 Gbytes of free disk space
                    for building images.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Meet Minimal Version Requirements:</emphasis>
                    The OpenEmbedded build system should be able to run on any
                    modern distribution that has the following versions for
                    Git, tar, and Python.
                    <itemizedlist>
                        <listitem><para>
                            Git 1.8.3.1 or greater
                            </para></listitem>
                        <listitem><para>
                            tar 1.27 or greater
                            </para></listitem>
                        <listitem><para>
                            Python 3.4.0 or greater.
                            </para></listitem>
                    </itemizedlist>
                    If your build host does not meet any of these three listed
                    version requirements, you can take steps to prepare the
                    system so that you can still use the Yocto Project.
                    See the
                    "<ulink url='&YOCTO_DOCS_REF_URL;#required-git-tar-and-python-versions'>Required Git, tar, and Python Versions</ulink>"
                    section in the Yocto Project Reference Manual for
                    information.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Install Development Host Packages:</emphasis>
                    Required development host packages vary depending on your
                    build machine and what you want to do with the Yocto
                    Project.
                    Collectively, the number of required packages is large
                    if you want to be able to cover all cases.</para>

                    <para>For lists of required packages for all scenarios,
                    see the
                    "<ulink url='&YOCTO_DOCS_REF_URL;#required-packages-for-the-host-development-system'>Required Packages for the Host Development System</ulink>"
                    section in the Yocto Project Reference Manual.
                    </para></listitem>
            </orderedlist>
            Once you have completed the previous steps, you are ready to
            continue using a given development path on your native Linux
            machine.
            If you are going to use BitBake, see the
            "<link linkend='cloning-the-poky-repository'>Cloning the <filename>poky</filename> Repository</link>"
            section.
            If you are going to use the Extensible SDK, see the
            "<ulink url='&YOCTO_DOCS_SDK_URL;#sdk-extensible'>Using the Extensible SDK</ulink>"
            Chapter in the Yocto Project Application Development and the
            Extensible Software Development Kit (eSDK) manual.
            If you want to work on the kernel, see the
            <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;'>Yocto Project Linux Kernel Development Manual</ulink>.
            If you are going to use Toaster, see the
            "<ulink url='&YOCTO_DOCS_TOAST_URL;#toaster-manual-setup-and-use'>Setting Up and Using Toaster</ulink>"
            section in the Toaster User Manual.
        </para>
    </section>

    <section id='setting-up-to-use-crops'>
        <title>Setting Up to Use CROss PlatformS (CROPS)</title>

        <para>
            With
            <ulink url='https://git.yoctoproject.org/cgit/cgit.cgi/crops/about/'>CROPS</ulink>,
            which leverages
            <ulink url='https://www.docker.com/'>Docker Containers</ulink>,
            you can create a Yocto Project development environment that
            is operating system agnostic.
            You can set up a container in which you can develop using the
            Yocto Project on a Windows, Mac, or Linux  machine.
        </para>

        <para>
            Follow these general steps to prepare a Windows, Mac, or Linux
            machine as your Yocto Project development host:
            <orderedlist>
                <listitem><para>
                    <emphasis>Go to the Docker Installation Site:</emphasis>
                    <ulink url='https://www.docker.com/what-docker'>Docker</ulink>
                    is a software container platform that you need to install
                    on the host development machine.
                    To start the installation process, see the
                    <ulink url='https://docs.docker.com/engine/installation/'>Docker Installation</ulink>
                    site.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Choose Your Docker Edition:</emphasis>
                    Docker comes in several editions.
                    For the Yocto Project, the stable community edition
                    (i.e. "Docker CE Stable") is adequate.
                    You can learn more about the Docker editions from the
                    site.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Go the Install Site for Your Platform:</emphasis>
                    Click the link for the Docker edition associated with
                    your development host machine's native software.
                    For example, if your machine is running Microsoft
                    Windows Version 10 and you want the Docker CE Stable
                    edition, click that link under "Supported Platforms".
                    </para></listitem>
                <listitem><para>
                    <emphasis>Understand What You Need:</emphasis>
                    The install page has pre-requisites your machine must
                    meet.
                    Be sure you read through this page and make sure your
                    machine meets the requirements to run Docker.
                    If your machine does not meet the requirements, the page
                    has instructions to handle exceptions.
                    For example, to run Docker on Windows 10, you must have
                    the pro version of the operating system.
                    If you have the home version, you need to install the
                    <ulink url='https://docs.docker.com/toolbox/overview/#ready-to-get-started'>Docker Toolbox</ulink>.
                    </para>

                    <para>Another example is that a Windows machine needs to
                    have Microsoft Hyper-V.
                    If you have a legacy version of the the Microsoft
                    operating system or for any other reason you do not have
                    Microsoft Hyper-V, you would have to enter the BIOS and
                    enable virtualization.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Install the Software:</emphasis>
                    Once you have understood all the pre-requisites, you can
                    download and install the appropriate software.
                    Follow the instructions for your specific machine and
                    the type of the software you need to install.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Optionally Orient Yourself With Dockers:</emphasis>
                    If you are unfamiliar with Dockers and the container
                    concept, you can learn more here -
                    <ulink url='https://docs.docker.com/get-started/'></ulink>.
                    You should be able to launch Docker or the Docker Toolbox
                    and have a terminal shell on your development host.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Set Up the Containers to Use the Yocto Project:</emphasis>
                    Go to
                    <ulink url='https://github.com/crops/docker-win-mac-docs/wiki'></ulink>
                    and follow the directions for your particular
                    development host (i.e. Linux, Mac, or Windows).</para>

                    <para>Once you complete the setup instructions for your
                    machine, you have the Poky, Extensible SDK, and Toaster
                    containers available.
                    You can click those links from the page and learn more
                    about using each of those containers.
                    </para></listitem>
            </orderedlist>
            Once you have a container set up, everything is in place to
            develop just as if you were running on a native Linux machine.
            If you are going to use the Poky container, see the
            "<link linkend='cloning-the-poky-repository'>Cloning the <filename>poky</filename> Repository</link>"
            section.
            If you are going to use the Extensible SDK container, see the
            "<ulink url='&YOCTO_DOCS_SDK_URL;#sdk-extensible'>Using the Extensible SDK</ulink>"
            Chapter in the Yocto Project Application Development and the
            Extensible Software Development Kit (eSDK) manual.
            If you are going to use the Toaster container, see the
            "<ulink url='&YOCTO_DOCS_TOAST_URL;#toaster-manual-setup-and-use'>Setting Up and Using Toaster</ulink>"
            section in the Toaster User Manual.
        </para>
    </section>
</section>

<section id='working-with-yocto-project-source-files'>
    <title>Working With Yocto Project Source Files</title>

    <para>
        This section contains procedures related to locating and securing
        Yocto Project files.
        You establish and use these local files to work on projects.
        <note><title>Notes</title>
            <itemizedlist>
                <listitem><para>
                    For concepts and introductory information about Git as it
                    is used in the Yocto Project, see the
                    "<ulink url='&YOCTO_DOCS_GS_URL;#git'>Git</ulink>"
                    section in the Yocto Project Overview Manual.
                    </para></listitem>
                <listitem><para>
                    For concepts on Yocto Project source repositories, see the
                    "<ulink url='&YOCTO_DOCS_GS_URL;#yocto-project-repositories'>Yocto Project Source Repositories</ulink>"
                    section in the Yocto Project Overview Manual."
                    </para></listitem>
            </itemizedlist>
        </note>
    </para>

    <section id='accessing-source-repositories'>
        <title>Accessing Source Repositories</title>

        <para>
            Working from a copy of the upstream Yocto Project
            <ulink url='&YOCTO_DOCS_GS_URL;#source-repositories'>Source Repositories</ulink>
            is the preferred method for obtaining and using a Yocto Project
            release.
            You can view the Yocto Project Source Repositories at
            <ulink url='&YOCTO_GIT_URL;/cgit.cgi'></ulink>.
            In particular, you can find the
            <filename>poky</filename> repository at
            <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi/poky/'></ulink>.
        </para>

        <para>
            Use the following procedure to locate the latest upstream copy of
            the <filename>poky</filename> Git repository:
            <orderedlist>
                <listitem><para>
                    <emphasis>Access Repositories:</emphasis>
                    Open a browser and go to
                    <ulink url='&YOCTO_GIT_URL;'></ulink> to access the
                    GUI-based interface into the Yocto Project source
                    repositories.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Select the Repository:</emphasis>
                    Click on the repository in which you are interested (i.e.
                    <filename>poky</filename>).
                    </para></listitem>
                <listitem><para>
                    <emphasis>Find the URL Used to Clone the Repository:</emphasis>
                    At the bottom of the page, note the URL used to
                    <ulink url='&YOCTO_DOCS_GS_URL;#git-commands-clone'>clone</ulink>
                    that repository (e.g.
                    <filename>&YOCTO_GIT_URL;/poky</filename>).
                    <note>
                        For information on cloning a repository, see the
                        "<link linkend='cloning-the-poky-repository'>Cloning the <filename>poky</filename> Repository</link>"
                        section.
                    </note>
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

    <section id='accessing-index-of-releases'>
        <title>Accessing Index of Releases</title>

        <para>
            Yocto Project maintains an Index of Releases area that contains
            related files that contribute to the Yocto Project.
            Rather than Git repositories, these files are tarballs that
            represent snapshots in time of a given component.
            <note><title>Tip</title>
                The recommended method for accessing Yocto Project
                components is to use Git to clone the upstream repository and
                work from within that locally cloned repository.
                The procedure in this section exists should you desire a
                tarball snapshot of any given component.
            </note>
            <orderedlist>
                <listitem><para>
                    <emphasis>Access the Index of Releases:</emphasis>
                    Open a browser and go to
                    <ulink url='&YOCTO_DL_URL;/releases'></ulink> to access the
                    Index of Releases.
                    The list represents released components (e.g.
                    <filename>eclipse-plugin</filename>,
                    <filename>sato</filename>, and so on).
                    <note>
                        The <filename>yocto</filename> directory contains the
                        full array of released Poky tarballs.
                        The <filename>poky</filename> directory in the
                        Index of Releases was historically used for very
                        early releases and exists now only for retroactive
                        completeness.
                    </note>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Select a Component:</emphasis>
                    Click on any released component in which you are interested
                    (e.g. <filename>yocto</filename>).
                    </para></listitem>
                <listitem><para>
                    <emphasis>Find the Tarball:</emphasis>
                    Drill down to find the associated tarball.
                    For example, click on <filename>yocto-&DISTRO;</filename> to
                    view files associated with the Yocto Project &DISTRO;
                    release (e.g. <filename>poky-&DISTRO_NAME_NO_CAP;-&POKYVERSION;.tar.bz2</filename>,
                    which is the released Poky tarball).
                    </para></listitem>
                <listitem><para>
                    <emphasis>Download the Tarball:</emphasis>
                    Click the tarball to download and save a snapshot of the
                    given component.
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

    <section id='using-the-downloads-page'>
        <title>Using the Downloads Page</title>

        <para>
            The
            <ulink url='&YOCTO_HOME_URL;'>Yocto Project Website</ulink>
            uses a "Downloads" area from which you can locate and download
            tarballs of any Yocto Project release.
            Rather than Git repositories, these files represent snapshot
            tarballs.
            <note><title>Tip</title>
                The recommended method for accessing Yocto Project
                components is to use Git to clone a repository and work from
                within that local repository.
                The procedure in this section exists should you desire a
                tarball snapshot of any given component.
            </note>
            <orderedlist>
                <listitem><para>
                    <emphasis>Go to the Yocto Project Website:</emphasis>
                    Open The
                    <ulink url='&YOCTO_HOME_URL;'>Yocto Project Website</ulink>
                    in your browser.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Get to the Downloads Area:</emphasis>
                    Click the "Downloads" tab.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Select the Type of Files:</emphasis>
                    Click the type of files you want such as "Build System",
                    "Tools", or "Board Support Packages (BSPs)".
                    </para></listitem>
                <listitem><para>
                    <emphasis>Locate and Download the Tarball:</emphasis>
                    From the list of releases, locate the appropriate
                    download link and download the files.
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

    <section id='accessing-nightly-builds'>
        <title>Accessing Nightly Builds</title>

        <para>
            Yocto Project maintains an area for nightly builds that contains
            tarball releases at <ulink url='&YOCTO_AB_NIGHTLY_URL;'/>.
            These builds include Yocto Project releases, SDK installation
            scripts, and experimental builds.
        </para>

        <para>
            Should you ever want to access a nightly build of a particular
            Yocto Project component, use the following procedure:
            <orderedlist>
                <listitem><para>
                    <emphasis>Access the Nightly Builds:</emphasis>
                    Open a browser and go to
                    <ulink url='&YOCTO_AB_NIGHTLY_URL;'/> to access the
                    Nightly Builds.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Select a Build:</emphasis>
                    Click on any build by date in which you are interested.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Find the Tarball:</emphasis>
                    Drill down to find the associated tarball.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Download the Tarball:</emphasis>
                    Click the tarball to download and save a snapshot of the
                    given component.
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

    <section id='cloning-the-poky-repository'>
        <title>Cloning the <filename>poky</filename> Repository</title>

        <para>
            To use the Yocto Project, you need a release of the Yocto Project
            locally installed on your development system.
            The locally installed set of files is referred to as the
            <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
            in the Yocto Project documentation.
        </para>

        <para>
            You create your Source Directory by using
            <ulink url='&YOCTO_DOCS_GS_URL;#git'>Git</ulink> to clone a local
            copy of the upstream <filename>poky</filename> repository.
            <note><title>Tip</title>
                The preferred method of getting the Yocto Project Source
                Directory set up is to clone the repository.
            </note>
            Working from a copy of the upstream repository allows you
            to contribute back into the Yocto Project or simply work with
            the latest software on a development branch.
            Because Git maintains and creates an upstream repository with
            a complete history of changes and you are working with a local
            clone of that repository, you have access to all the Yocto
            Project development branches and tag names used in the upstream
            repository.
        </para>

        <para>
            Follow these steps to create a local version of the
            upstream
            <ulink url='&YOCTO_DOCS_REF_URL;#poky'><filename>poky</filename></ulink>
            Git repository.
            <orderedlist>
                <listitem><para>
                    <emphasis>Set Your Directory:</emphasis>
                    Be in the directory where you want to create your local
                    copy of poky.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Clone the Repository:</emphasis>
                    The following command clones the repository and uses
                    the default name "poky" for your local repository:
                    <literallayout class='monospaced'>
     $ git clone git://git.yoctoproject.org/poky
     Cloning into 'poky'...
     remote: Counting objects: 367178, done.
     remote: Compressing objects: 100% (88161/88161), done.
     remote: Total 367178 (delta 272761), reused 366942 (delta 272525)
     Receiving objects: 100% (367178/367178), 133.26 MiB | 6.40 MiB/s, done.
     Resolving deltas: 100% (272761/272761), done.
     Checking connectivity... done.
                    </literallayout>
                    Unless you specify a specific development branch or
                    tag name, Git clones the "master" branch, which results
                    in a snapshot of the latest development changes for
                    "master".
                    For information on how to check out a specific
                    development branch or on how to check out a local
                    branch based on a tag name, see the
                    "<link linkend='checking-out-by-branch-in-poky'>Checking Out By Branch in Poky</link>"
                    and
                    <link linkend='checkout-out-by-tag-in-poky'>Checking Out By Tag in Poky</link>",
                    respectively.</para>

                    <para>Once the repository is created, you can change to
                    that directory and check its status.
                    Here, the single "master" branch exists on your system
                    and by default, it is checked out:
                    <literallayout class='monospaced'>
     $ cd ~/poky
     $ git status
     On branch master
     Your branch is up-to-date with 'origin/master'.
     nothing to commit, working directory clean
     $ git branch
     * master
                    </literallayout>
                    Your local repository of poky is identical to the
                    upstream poky repository at the time from which it was
                    cloned.
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

    <section id='checking-out-by-branch-in-poky'>
        <title>Checking Out by Branch in Poky</title>

        <para>
            When you clone the upstream poky repository, you have access to
            all its development branches.
            Each development branch in a repository is unique as it forks
            off the "master" branch.
            To see and use the files of a particular development branch
            locally, you need to know the branch name and then specifically
            check out that development branch.
            <note>
                Checking out an active development branch by branch name
                gives you a snapshot of that particular branch at the time
                you check it out.
                Further development on top of the branch that occurs after
                check it out can occur.
            </note>
            <orderedlist>
                <listitem><para>
                    <emphasis>Switch to the Poky Directory:</emphasis>
                    If you have a local poky Git repository, switch to that
                    directory.
                    If you do not have the local copy of poky, see the
                    "<link linkend='cloning-the-poky-repository'>Cloning the <filename>poky</filename> Repository</link>"
                    section.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Determine Existing Branch Names:</emphasis>
                    <literallayout class='monospaced'>
     $ git branch -a
     * master
       remotes/origin/1.1_M1
       remotes/origin/1.1_M2
       remotes/origin/1.1_M3
       remotes/origin/1.1_M4
       remotes/origin/1.2_M1
       remotes/origin/1.2_M2
       remotes/origin/1.2_M3
           .
           .
           .
       remotes/origin/master-next
       remotes/origin/master-next2
       remotes/origin/morty
       remotes/origin/pinky
       remotes/origin/purple
       remotes/origin/pyro
       remotes/origin/rocko
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Checkout the Branch:</emphasis>
                    Checkout the development branch in which you want to work.
                    For example, to access the files for the Yocto Project
                    &DISTRO; Release (&DISTRO_NAME;), use the following command:
                    <literallayout class='monospaced'>
     $ git checkout -b &DISTRO_NAME_NO_CAP; origin/&DISTRO_NAME_NO_CAP;
     Branch &DISTRO_NAME_NO_CAP; set up to track remote branch &DISTRO_NAME_NO_CAP; from origin.
     Switched to a new branch '&DISTRO_NAME_NO_CAP;'
                    </literallayout>
                    The previous command checks out the "&DISTRO_NAME_NO_CAP;"
                    development branch and reports that the branch is tracking
                    the upstream "origin/&DISTRO_NAME_NO_CAP;" branch.</para>

                    <para>The following command displays the branches
                    that are now part of your local poky repository.
                    The asterisk character indicates the branch that is
                    currently checked out for work:
                    <literallayout class='monospaced'>
     $ git branch
       master
     * &DISTRO_NAME_NO_CAP;
                    </literallayout>
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

    <section id='checkout-out-by-tag-in-poky'>
        <title>Checking Out by Tag in Poky</title>

        <para>
            Similar to branches, the upstream repository uses tags
            to mark specific commits associated with significant points in
            a development branch (i.e. a release point or stage of a
            release).
            You might want to set up a local branch based on one of those
            points in the repository.
            The process is similar to checking out by branch name except you
            use tag names.
            <note>
                Checking out a branch based on a tag gives you a
                stable set of files not affected by development on the
                branch above the tag.
            </note>
            <orderedlist>
                <listitem><para>
                    <emphasis>Switch to the Poky Directory:</emphasis>
                    If you have a local poky Git repository, switch to that
                    directory.
                    If you do not have the local copy of poky, see the
                    "<link linkend='cloning-the-poky-repository'>Cloning the <filename>poky</filename> Repository</link>"
                    section.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Fetch the Tag Names:</emphasis>
                    To checkout the branch based on a tag name, you need to
                    fetch the upstream tags into your local repository:
                    <literallayout class='monospaced'>
     $ git fetch --tags
     $
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    <emphasis>List the Tag Names:</emphasis>
                    You can list the tag names now:
                    <literallayout class='monospaced'>
     $ git tag
     1.1_M1.final
     1.1_M1.rc1
     1.1_M1.rc2
     1.1_M2.final
     1.1_M2.rc1
        .
        .
        .
     yocto-2.2
     yocto-2.2.1
     yocto-2.3
     yocto-2.3.1
     yocto-2.4
     yocto_1.5_M5.rc8
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Checkout the Branch:</emphasis>
                    <literallayout class='monospaced'>
     $ git checkout tags/&DISTRO; -b my_yocto_&DISTRO;
     Switched to a new branch 'my_yocto_&DISTRO;'
     $ git branch
       master
     * my_yocto_&DISTRO;
                    </literallayout>
                    The previous command creates and checks out a local
                    branch named "my_yocto_&DISTRO;", which is based on
                    the commit in the upstream poky repository that has
                    the same tag.
                    In this example, the files you have available locally
                    as a result of the <filename>checkout</filename>
                    command are a snapshot of the
                    "&DISTRO_NAME_NO_CAP;" development branch at the point
                    where Yocto Project &DISTRO; was released.
                    </para></listitem>
            </orderedlist>
        </para>
    </section>
</section>

<section id='dev-building-an-image'>
    <title>Building an Image</title>

    <para>
        In the development environment, you need to build an image whenever
        you change hardware support, add or change system libraries, or add
        or change services that have dependencies.
        Several methods exist that allow you to build an image within the
        Yocto Project.
        This section shows you how to build an image using BitBake from a
        Linux host.
        <note><title>Notes</title>
            <itemizedlist>
                <listitem><para>
                    For information on how to build an image using
                    <ulink url='&YOCTO_DOCS_REF_URL;#toaster-term'>Toaster</ulink>,
                    see the
                    <ulink url='&YOCTO_DOCS_TOAST_URL;'>Toaster Manual</ulink>.
                    </para></listitem>
                <listitem><para>
                    For information on how to use
                    <filename>devtool</filename> to build images, see the
                    "<ulink url='&YOCTO_DOCS_SDK_URL;#using-devtool-in-your-sdk-workflow'>Using <filename>devtool</filename> in Your SDK Workflow</ulink>"
                    section in the Yocto Project Application Development and
                    the Extensible Software Development Kit (eSDK) manual.
                    </para></listitem>
                <listitem><para>
                    For a practical example on how to build an image using the
                    OpenEmbedded build system, see the
                    "<ulink url='&YOCTO_DOCS_QS_URL;#qs-building-images'>Building Images</ulink>"
                    section of the Yocto Project Quick Start.
                    </para></listitem>
            </itemizedlist>
        </note>
    </para>

    <para>
        The build process creates an entire Linux distribution from source
        and places it in your
        <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
        under <filename>tmp/deploy/images</filename>.
        For detailed information on the build process using BitBake, see the
        "<ulink url='&YOCTO_DOCS_GS_URL;#images-dev-environment'>Images</ulink>"
        section in the Yocto Project Overview Manual.
    </para>

    <para>
        The following figure and list overviews the build process:
        <imagedata fileref="figures/bitbake-build-flow.png" width="7in" depth="4in" align="center" scalefit="1" />
        <orderedlist>
            <listitem><para>
                <emphasis>Set up Your Host Development System to Support
                Development Using the Yocto Project</emphasis>:
                See the
                "<ulink url='&YOCTO_DOCS_QS_URL;#yp-resources'>Setting Up to Use the Yocto Project</ulink>"
                section in the Yocto Project Quick Start for options on how
                to get a build host ready to use the Yocto Project.
                </para></listitem>
            <listitem><para>
                <emphasis>Initialize the Build Environment:</emphasis>
                Initialize the build environment by sourcing the build
                environment script (i.e.
                <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink>):
                <literallayout class='monospaced'>
     $ source &OE_INIT_FILE; [<replaceable>build_dir</replaceable>]
                </literallayout></para>

                <para>When you use the initialization script, the
                OpenEmbedded build system uses <filename>build</filename> as
                the default Build Directory in your current work directory.
                You can use a <replaceable>build_dir</replaceable> argument
                with the script to specify a different build directory.
                <note><title>Tip</title>
                    A common practice is to use a different Build Directory for
                    different targets.
                    For example, <filename>~/build/x86</filename> for a
                    <filename>qemux86</filename> target, and
                    <filename>~/build/arm</filename> for a
                    <filename>qemuarm</filename> target.
                </note>
                </para></listitem>
            <listitem><para>
                <emphasis>Make Sure Your <filename>local.conf</filename>
                File is Correct:</emphasis>
                Ensure the <filename>conf/local.conf</filename> configuration
                file, which is found in the Build Directory,
                is set up how you want it.
                This file defines many aspects of the build environment
                including the target machine architecture through the
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'>MACHINE</ulink></filename> variable,
                the packaging format used during the build
                (<ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></ulink>),
                and a centralized tarball download directory through the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'><filename>DL_DIR</filename></ulink> variable.
                </para></listitem>
            <listitem><para>
                <emphasis>Build the Image:</emphasis>
                Build the image using the <filename>bitbake</filename> command:
                <literallayout class='monospaced'>
     $ bitbake <replaceable>target</replaceable>
                </literallayout>
                <note>
                    For information on BitBake, see the
                    <ulink url='&YOCTO_DOCS_BB_URL;'>BitBake User Manual</ulink>.
                </note>
                The <replaceable>target</replaceable> is the name of the
                recipe you want to build.
                Common targets are the images in
                <filename>meta/recipes-core/images</filename>,
                <filename>meta/recipes-sato/images</filename>, etc. all found
                in the
                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
                Or, the target can be the name of a recipe for a specific
                piece of software such as BusyBox.
                For more details about the images the OpenEmbedded build
                system supports, see the
                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>"
                chapter in the Yocto Project Reference Manual.</para>

                <para>As an example, the following command builds the
                <filename>core-image-minimal</filename> image:
                <literallayout class='monospaced'>
     $ bitbake core-image-minimal
                </literallayout>
                Once an image has been built, it often needs to be installed.
                The images and kernels built by the OpenEmbedded build system
                are placed in the Build Directory in
                <filename class="directory">tmp/deploy/images</filename>.
                For information on how to run pre-built images such as
                <filename>qemux86</filename> and <filename>qemuarm</filename>,
                see the
                <ulink url='&YOCTO_DOCS_SDK_URL;'>Yocto Project Application Development and the Extensible Software Development Kit (eSDK)</ulink>
                manual.
                For information about how to install these images, see the
                documentation for your particular board or machine.
                </para></listitem>
        </orderedlist>
    </para>
</section>

<section id='speeding-up-the-build'>
    <title>Speeding Up the Build</title>

    <para>
        Build time can be an issue.
        By default, the build system uses simple controls to try and maximize
        build efficiency.
        In general, the default settings for all the following variables
        result in the most efficient build times when dealing with single
        socket systems (i.e. a single CPU).
        If you have multiple CPUs, you might try increasing the default
        values to gain more speed.
        See the descriptions in the glossary for each variable for more
        information:
        <itemizedlist>
            <listitem><para>
                <ulink url='&YOCTO_DOCS_REF_URL;#var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename>:</ulink>
                The maximum number of threads BitBake simultaneously executes.
                </para></listitem>
            <listitem><para>
                <ulink url='&YOCTO_DOCS_BB_URL;#var-BB_NUMBER_PARSE_THREADS'><filename>BB_NUMBER_PARSE_THREADS</filename>:</ulink>
                The number of threads BitBake uses during parsing.
                </para></listitem>
            <listitem><para>
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename>:</ulink>
                Extra options passed to the <filename>make</filename> command
                during the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-compile'><filename>do_compile</filename></ulink>
                task in order to specify parallel compilation on the
                local build host.
                </para></listitem>
            <listitem><para>
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKEINST'><filename>PARALLEL_MAKEINST</filename>:</ulink>
                Extra options passed to the <filename>make</filename> command
                during the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
                task in order to specify parallel installation on the
                local build host.
                </para></listitem>
        </itemizedlist>
        As mentioned, these variables all scale to the number of processor
        cores available on the build system.
        For single socket systems, this auto-scaling ensures that the build
        system fundamentally takes advantage of potential parallel operations
        during the build based on the build machine's capabilities.
    </para>

    <para>
        Following are additional factors that can affect build speed:
        <itemizedlist>
            <listitem><para>
                File system type:
                The file system type that the build is being performed on can
                also influence performance.
                Using <filename>ext4</filename> is recommended as compared
                to <filename>ext2</filename> and <filename>ext3</filename>
                due to <filename>ext4</filename> improved features
                such as extents.
                </para></listitem>
            <listitem><para>
                Disabling the updating of access time using
                <filename>noatime</filename>:
                The <filename>noatime</filename> mount option prevents the
                build system from updating file and directory access times.
                </para></listitem>
            <listitem><para>
                Setting a longer commit:
                Using the "commit=" mount option increases the interval
                in seconds between disk cache writes.
                Changing this interval from the five second default to
                something longer increases the risk of data loss but decreases
                the need to write to the disk, thus increasing the build
                performance.
                </para></listitem>
            <listitem><para>
                Choosing the packaging backend:
                Of the available packaging backends, IPK is the fastest.
                Additionally, selecting a singular packaging backend also
                helps.
                </para></listitem>
            <listitem><para>
                Using <filename>tmpfs</filename> for
                <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>
                as a temporary file system:
                While this can help speed up the build, the benefits are
                limited due to the compiler using
                <filename>-pipe</filename>.
                The build system goes to some lengths to avoid
                <filename>sync()</filename> calls into the
                file system on the principle that if there was a significant
                failure, the
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
                contents could easily be rebuilt.
                </para></listitem>
            <listitem><para>
                Inheriting the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-rm-work'><filename>rm_work</filename></ulink>
                class:
                Inheriting this class has shown to speed up builds due to
                significantly lower amounts of data stored in the data
                cache as well as on disk.
                Inheriting this class also makes cleanup of
                <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>
                faster, at the expense of being easily able to dive into the
                source code.
                File system maintainers have recommended that the fastest way
                to clean up large numbers of files is to reformat partitions
                rather than delete files due to the linear nature of
                partitions.
                This, of course, assumes you structure the disk partitions and
                file systems in a way that this is practical.
                </para></listitem>
        </itemizedlist>
        Aside from the previous list, you should keep some trade offs in
        mind that can help you speed up the build:
        <itemizedlist>
            <listitem><para>
                Remove items from
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></ulink>
                that you might not need.
                </para></listitem>
            <listitem><para>
                Exclude debug symbols and other debug information:
                If you do not need these symbols and other debug information,
                disabling the <filename>*-dbg</filename> package generation
                can speed up the build.
                You can disable this generation by setting the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-INHIBIT_PACKAGE_DEBUG_SPLIT'><filename>INHIBIT_PACKAGE_DEBUG_SPLIT</filename></ulink>
                variable to "1".
                </para></listitem>
            <listitem><para>
                Disable static library generation for recipes derived from
                <filename>autoconf</filename> or <filename>libtool</filename>:
                Following is an example showing how to disable static
                libraries and still provide an override to handle exceptions:
                <literallayout class='monospaced'>
     STATICLIBCONF = "--disable-static"
     STATICLIBCONF_sqlite3-native = ""
     EXTRA_OECONF += "${STATICLIBCONF}"
                </literallayout>
                <note><title>Notes</title>
                    <itemizedlist>
                        <listitem><para>
                            Some recipes need static libraries in order to work
                            correctly (e.g. <filename>pseudo-native</filename>
                            needs <filename>sqlite3-native</filename>).
                            Overrides, as in the previous example, account for
                            these kinds of exceptions.
                            </para></listitem>
                        <listitem><para>
                            Some packages have packaging code that assumes the
                            presence of the static libraries.
                            If so, you might need to exclude them as well.
                            </para></listitem>
                    </itemizedlist>
                </note>
            </para></listitem>
        </itemizedlist>
    </para>
</section>
</chapter>
<!--
vim: expandtab tw=80 ts=4
-->