summaryrefslogtreecommitdiffstats
path: root/documentation/dev-manual/dev-manual-common-tasks.xml
blob: e88d4a796cb0d3c1bc33ff990760f54d8334e965 (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
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
6301
6302
6303
6304
6305
6306
6307
6308
6309
6310
6311
6312
6313
6314
6315
6316
6317
6318
6319
6320
6321
6322
6323
6324
6325
6326
6327
6328
6329
6330
6331
6332
6333
6334
6335
6336
6337
6338
6339
6340
6341
6342
6343
6344
6345
6346
6347
6348
6349
6350
6351
6352
6353
6354
6355
6356
6357
6358
6359
6360
6361
6362
6363
6364
6365
6366
6367
6368
6369
6370
6371
6372
6373
6374
6375
6376
6377
6378
6379
6380
6381
6382
6383
6384
6385
6386
6387
6388
6389
6390
6391
6392
6393
6394
6395
6396
6397
6398
6399
6400
6401
6402
6403
6404
6405
6406
6407
6408
6409
6410
6411
6412
6413
6414
6415
6416
6417
6418
6419
6420
6421
6422
6423
6424
6425
6426
6427
6428
6429
6430
6431
6432
6433
6434
6435
6436
6437
6438
6439
6440
6441
6442
6443
6444
6445
6446
6447
6448
6449
6450
6451
6452
6453
6454
6455
6456
6457
6458
6459
6460
6461
6462
6463
6464
6465
6466
6467
6468
6469
6470
6471
6472
6473
6474
6475
6476
6477
6478
6479
6480
6481
6482
6483
6484
6485
6486
6487
6488
6489
6490
6491
6492
6493
6494
6495
6496
6497
6498
6499
6500
6501
6502
6503
6504
6505
6506
6507
6508
6509
6510
6511
6512
6513
6514
6515
6516
6517
6518
6519
6520
6521
6522
6523
6524
6525
6526
6527
6528
6529
6530
6531
6532
6533
6534
6535
6536
6537
6538
6539
6540
6541
6542
6543
6544
6545
6546
6547
6548
6549
6550
6551
6552
6553
6554
6555
6556
6557
6558
6559
6560
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
6577
6578
6579
6580
6581
6582
6583
6584
6585
6586
6587
6588
6589
6590
6591
6592
6593
6594
6595
6596
6597
6598
6599
6600
6601
6602
6603
6604
6605
6606
6607
6608
6609
6610
6611
6612
6613
6614
6615
6616
6617
6618
6619
6620
6621
6622
6623
6624
6625
6626
6627
6628
6629
6630
6631
6632
6633
6634
6635
6636
6637
6638
6639
6640
6641
6642
6643
6644
6645
6646
6647
6648
6649
6650
6651
6652
6653
6654
6655
6656
6657
6658
6659
6660
6661
6662
6663
6664
6665
6666
6667
6668
6669
6670
6671
6672
6673
6674
6675
6676
6677
6678
6679
6680
6681
6682
6683
6684
6685
6686
6687
6688
6689
6690
6691
6692
6693
6694
6695
6696
6697
6698
6699
6700
6701
6702
6703
6704
6705
6706
6707
6708
6709
6710
6711
6712
6713
6714
6715
6716
6717
6718
6719
6720
6721
6722
6723
6724
6725
6726
6727
6728
6729
6730
6731
6732
6733
6734
6735
6736
6737
6738
6739
6740
6741
6742
6743
6744
6745
6746
6747
6748
6749
6750
6751
6752
6753
6754
6755
6756
6757
6758
6759
6760
6761
6762
6763
6764
6765
6766
6767
6768
6769
6770
6771
6772
6773
6774
6775
6776
6777
6778
6779
6780
6781
6782
6783
6784
6785
6786
6787
6788
6789
6790
6791
6792
6793
6794
6795
6796
6797
6798
6799
6800
6801
6802
6803
6804
6805
6806
6807
6808
6809
6810
6811
6812
6813
6814
6815
6816
6817
6818
6819
6820
6821
6822
6823
6824
6825
6826
6827
6828
6829
6830
6831
6832
6833
6834
6835
6836
6837
6838
6839
6840
6841
6842
6843
6844
6845
6846
6847
6848
6849
6850
6851
6852
6853
6854
6855
6856
6857
6858
6859
6860
6861
6862
6863
6864
6865
6866
6867
6868
6869
6870
6871
6872
6873
6874
6875
6876
6877
6878
6879
6880
6881
6882
6883
6884
6885
6886
6887
6888
6889
6890
6891
6892
6893
6894
6895
6896
6897
6898
6899
6900
6901
6902
6903
6904
6905
6906
6907
6908
6909
6910
6911
6912
6913
6914
6915
6916
6917
6918
6919
6920
6921
6922
6923
6924
6925
6926
6927
6928
6929
6930
6931
6932
6933
6934
6935
6936
6937
6938
6939
6940
6941
6942
6943
6944
6945
6946
6947
6948
6949
6950
6951
6952
6953
6954
6955
6956
6957
6958
6959
6960
6961
6962
6963
6964
6965
6966
6967
6968
6969
6970
6971
6972
6973
6974
6975
6976
6977
6978
6979
6980
6981
6982
6983
6984
6985
6986
6987
6988
6989
6990
6991
6992
6993
6994
6995
6996
6997
6998
6999
7000
7001
7002
7003
7004
7005
7006
7007
7008
7009
7010
7011
7012
7013
7014
7015
7016
7017
7018
7019
7020
7021
7022
7023
7024
7025
7026
7027
7028
7029
7030
7031
7032
7033
7034
7035
7036
7037
7038
7039
7040
7041
7042
7043
7044
7045
7046
7047
7048
7049
7050
7051
7052
7053
7054
7055
7056
7057
7058
7059
7060
7061
7062
7063
7064
7065
7066
7067
7068
7069
7070
7071
7072
7073
7074
7075
7076
7077
7078
7079
7080
7081
7082
7083
7084
7085
7086
7087
7088
7089
7090
7091
7092
7093
7094
7095
7096
7097
7098
7099
7100
7101
7102
7103
7104
7105
7106
7107
7108
7109
7110
7111
7112
7113
7114
7115
7116
7117
7118
7119
7120
7121
7122
7123
7124
7125
7126
7127
7128
7129
7130
7131
7132
7133
7134
7135
7136
7137
7138
7139
7140
7141
7142
7143
7144
7145
7146
7147
7148
7149
7150
7151
7152
7153
7154
7155
7156
7157
7158
7159
7160
7161
7162
7163
7164
7165
7166
7167
7168
7169
7170
7171
7172
7173
7174
7175
7176
7177
7178
7179
7180
7181
7182
7183
7184
7185
7186
7187
7188
7189
7190
7191
7192
7193
7194
7195
7196
7197
7198
7199
7200
7201
7202
7203
7204
7205
7206
7207
7208
7209
7210
7211
7212
7213
7214
7215
7216
7217
7218
7219
7220
7221
7222
7223
7224
7225
7226
7227
7228
7229
7230
7231
7232
7233
7234
7235
7236
7237
7238
7239
7240
7241
7242
7243
7244
7245
7246
7247
7248
7249
7250
7251
7252
7253
7254
7255
7256
7257
7258
7259
7260
7261
7262
7263
7264
7265
7266
7267
7268
7269
7270
7271
7272
7273
7274
7275
7276
7277
7278
7279
7280
7281
7282
7283
7284
7285
7286
7287
7288
7289
7290
7291
7292
7293
7294
7295
7296
7297
7298
7299
7300
7301
7302
7303
7304
7305
7306
7307
7308
7309
7310
7311
7312
7313
7314
7315
7316
7317
7318
7319
7320
7321
7322
7323
7324
7325
7326
7327
7328
7329
7330
7331
7332
7333
7334
7335
7336
7337
7338
7339
7340
7341
7342
7343
7344
7345
7346
7347
7348
7349
7350
7351
7352
7353
7354
7355
7356
7357
7358
7359
7360
7361
7362
7363
7364
7365
7366
7367
7368
7369
7370
7371
7372
7373
7374
7375
7376
7377
7378
7379
7380
7381
7382
7383
7384
7385
7386
7387
7388
7389
7390
7391
7392
7393
7394
7395
7396
7397
7398
7399
7400
7401
7402
7403
7404
7405
7406
7407
7408
7409
7410
7411
7412
7413
7414
7415
7416
7417
7418
7419
7420
7421
7422
7423
7424
7425
7426
7427
7428
7429
7430
7431
7432
7433
7434
7435
7436
7437
7438
7439
7440
7441
7442
7443
7444
7445
7446
7447
7448
7449
7450
7451
7452
7453
7454
7455
7456
7457
7458
7459
7460
7461
7462
7463
7464
7465
7466
7467
7468
7469
7470
7471
7472
7473
7474
7475
7476
7477
7478
7479
7480
7481
7482
7483
7484
7485
7486
7487
7488
7489
7490
7491
7492
7493
7494
7495
7496
7497
7498
7499
7500
7501
7502
7503
7504
7505
7506
7507
7508
7509
7510
7511
7512
7513
7514
7515
7516
7517
7518
7519
7520
7521
7522
7523
7524
7525
7526
7527
7528
7529
7530
7531
7532
7533
7534
7535
7536
7537
7538
7539
7540
7541
7542
7543
7544
7545
7546
7547
7548
7549
7550
7551
7552
7553
7554
7555
7556
7557
7558
7559
7560
7561
7562
7563
7564
7565
7566
7567
7568
7569
7570
7571
7572
7573
7574
7575
7576
7577
7578
7579
7580
7581
7582
7583
7584
7585
7586
7587
7588
7589
7590
7591
7592
7593
7594
7595
7596
7597
7598
7599
7600
7601
7602
7603
7604
7605
7606
7607
7608
7609
7610
7611
7612
7613
7614
7615
7616
7617
7618
7619
7620
7621
7622
7623
7624
7625
7626
7627
7628
7629
7630
7631
7632
7633
7634
7635
7636
7637
7638
7639
7640
7641
7642
7643
7644
7645
7646
7647
7648
7649
7650
7651
7652
7653
7654
7655
7656
7657
7658
7659
7660
7661
7662
7663
7664
7665
7666
7667
7668
7669
7670
7671
7672
7673
7674
7675
7676
7677
7678
7679
7680
7681
7682
7683
7684
7685
7686
7687
7688
7689
7690
7691
7692
7693
7694
7695
7696
7697
7698
7699
7700
7701
7702
7703
7704
7705
7706
7707
7708
7709
7710
7711
7712
7713
7714
7715
7716
7717
7718
7719
7720
7721
7722
7723
7724
7725
7726
7727
7728
7729
7730
7731
7732
7733
7734
7735
7736
7737
7738
7739
7740
7741
7742
7743
7744
7745
7746
7747
7748
7749
7750
7751
7752
7753
7754
7755
7756
7757
7758
7759
7760
7761
7762
7763
7764
7765
7766
7767
7768
7769
7770
7771
7772
7773
7774
7775
7776
7777
7778
7779
7780
7781
7782
7783
7784
7785
7786
7787
7788
7789
7790
7791
7792
7793
7794
7795
7796
7797
7798
7799
7800
7801
7802
7803
7804
7805
7806
7807
7808
7809
7810
7811
7812
7813
7814
7815
7816
7817
7818
7819
7820
7821
7822
7823
7824
7825
7826
7827
7828
7829
7830
7831
7832
7833
7834
7835
7836
7837
7838
7839
7840
7841
7842
7843
7844
7845
7846
7847
7848
7849
7850
7851
7852
7853
7854
7855
7856
7857
7858
7859
7860
7861
7862
7863
7864
7865
7866
7867
7868
7869
7870
7871
7872
7873
7874
7875
7876
7877
7878
7879
7880
7881
7882
7883
7884
7885
7886
7887
7888
7889
7890
7891
7892
7893
7894
7895
7896
7897
7898
7899
7900
7901
7902
7903
7904
7905
7906
7907
7908
7909
7910
7911
7912
7913
7914
7915
7916
7917
7918
7919
7920
7921
7922
7923
7924
7925
7926
7927
7928
7929
7930
7931
7932
7933
7934
7935
7936
7937
7938
7939
7940
7941
7942
7943
7944
7945
7946
7947
7948
7949
7950
7951
7952
7953
7954
7955
7956
7957
7958
7959
7960
7961
7962
7963
7964
7965
7966
7967
7968
7969
7970
7971
7972
7973
7974
7975
7976
7977
7978
7979
7980
7981
7982
7983
7984
7985
7986
7987
7988
7989
7990
7991
7992
7993
7994
7995
7996
7997
7998
7999
8000
8001
8002
8003
8004
8005
8006
8007
8008
8009
8010
8011
8012
8013
8014
8015
8016
8017
8018
8019
8020
8021
8022
8023
8024
8025
8026
8027
8028
8029
8030
8031
8032
8033
8034
8035
8036
8037
8038
8039
8040
8041
8042
8043
8044
8045
8046
8047
8048
8049
8050
8051
8052
8053
8054
8055
8056
8057
8058
8059
8060
8061
8062
8063
8064
8065
8066
8067
8068
8069
8070
8071
8072
8073
8074
8075
8076
8077
8078
8079
8080
8081
8082
8083
8084
8085
8086
8087
8088
8089
8090
8091
8092
8093
8094
8095
8096
8097
8098
8099
8100
8101
8102
8103
8104
8105
8106
8107
8108
8109
8110
8111
8112
8113
8114
8115
8116
8117
8118
8119
8120
8121
8122
8123
8124
8125
8126
8127
8128
8129
8130
8131
8132
8133
8134
8135
8136
8137
8138
8139
8140
8141
8142
8143
8144
8145
8146
8147
8148
8149
8150
8151
8152
8153
8154
8155
8156
8157
8158
8159
8160
8161
8162
8163
8164
8165
8166
8167
8168
8169
8170
8171
8172
8173
8174
8175
8176
8177
8178
8179
8180
8181
8182
8183
8184
8185
8186
8187
8188
8189
8190
8191
8192
8193
8194
8195
8196
8197
8198
8199
8200
8201
8202
8203
8204
8205
8206
8207
8208
8209
8210
8211
8212
8213
8214
8215
8216
8217
8218
8219
8220
8221
8222
8223
8224
8225
8226
8227
8228
8229
8230
8231
8232
8233
8234
8235
8236
8237
8238
8239
8240
8241
8242
8243
8244
8245
8246
8247
8248
8249
8250
8251
8252
8253
8254
8255
8256
8257
8258
8259
8260
8261
8262
8263
8264
8265
8266
8267
8268
8269
8270
8271
8272
8273
8274
8275
8276
8277
8278
8279
8280
8281
8282
8283
8284
8285
8286
8287
8288
8289
8290
8291
8292
8293
8294
8295
8296
8297
8298
8299
8300
8301
8302
8303
8304
8305
8306
8307
8308
8309
8310
8311
8312
8313
8314
8315
8316
8317
8318
8319
8320
8321
8322
8323
8324
8325
8326
8327
8328
8329
8330
8331
8332
8333
8334
8335
8336
8337
8338
8339
8340
8341
8342
8343
8344
8345
8346
8347
8348
8349
8350
8351
8352
8353
8354
8355
8356
8357
8358
8359
8360
8361
8362
8363
8364
8365
8366
8367
8368
8369
8370
8371
8372
8373
8374
8375
8376
8377
8378
8379
8380
8381
8382
8383
8384
8385
8386
8387
8388
8389
8390
8391
8392
8393
8394
8395
8396
8397
8398
8399
8400
8401
8402
8403
8404
8405
8406
8407
8408
8409
8410
8411
8412
8413
8414
8415
8416
8417
8418
8419
8420
8421
8422
8423
8424
8425
8426
8427
8428
8429
8430
8431
8432
8433
8434
8435
8436
8437
8438
8439
8440
8441
8442
8443
8444
8445
8446
8447
8448
8449
8450
8451
8452
8453
8454
8455
8456
8457
8458
8459
8460
8461
8462
8463
8464
8465
8466
8467
8468
8469
8470
8471
8472
8473
8474
8475
8476
8477
8478
8479
8480
8481
8482
8483
8484
8485
8486
8487
8488
8489
8490
8491
8492
8493
8494
8495
8496
8497
8498
8499
8500
8501
8502
8503
8504
8505
8506
8507
8508
8509
8510
8511
8512
8513
8514
8515
8516
8517
8518
8519
8520
8521
8522
8523
8524
8525
8526
8527
8528
8529
8530
8531
8532
8533
8534
8535
8536
8537
8538
8539
8540
8541
8542
8543
8544
8545
8546
8547
8548
8549
8550
8551
8552
8553
8554
8555
8556
8557
8558
8559
8560
8561
8562
8563
8564
8565
8566
8567
8568
8569
8570
8571
8572
8573
8574
8575
8576
8577
8578
8579
8580
8581
8582
8583
8584
8585
8586
8587
8588
8589
8590
8591
8592
8593
8594
8595
8596
8597
8598
8599
8600
8601
8602
8603
8604
8605
8606
8607
8608
8609
8610
8611
8612
8613
8614
8615
8616
8617
8618
8619
8620
8621
8622
8623
8624
8625
8626
8627
8628
8629
8630
8631
8632
8633
8634
8635
8636
8637
8638
8639
8640
8641
8642
8643
8644
8645
8646
8647
8648
8649
8650
8651
8652
8653
8654
8655
8656
8657
8658
8659
8660
8661
8662
8663
8664
8665
8666
8667
8668
8669
8670
8671
8672
8673
8674
8675
8676
8677
8678
8679
8680
8681
8682
8683
8684
8685
8686
8687
8688
8689
8690
8691
8692
8693
8694
8695
8696
8697
8698
8699
8700
8701
8702
8703
8704
8705
8706
8707
8708
8709
8710
8711
8712
8713
8714
8715
8716
8717
8718
8719
8720
8721
8722
8723
8724
8725
8726
8727
8728
8729
8730
8731
8732
8733
8734
8735
8736
8737
8738
8739
8740
8741
8742
8743
8744
8745
8746
8747
8748
8749
8750
8751
8752
8753
8754
8755
8756
8757
8758
8759
8760
8761
8762
8763
8764
8765
8766
8767
8768
8769
8770
8771
8772
8773
8774
8775
8776
8777
8778
8779
8780
8781
8782
8783
8784
8785
8786
8787
8788
8789
8790
8791
8792
8793
8794
8795
8796
8797
8798
8799
8800
8801
8802
8803
8804
8805
8806
8807
8808
8809
8810
8811
8812
8813
8814
8815
8816
8817
8818
8819
8820
8821
8822
8823
8824
8825
8826
8827
8828
8829
8830
8831
8832
8833
8834
8835
8836
8837
8838
8839
8840
8841
8842
8843
8844
8845
8846
8847
8848
8849
8850
8851
8852
8853
8854
8855
8856
8857
8858
8859
8860
8861
8862
8863
8864
8865
8866
8867
8868
8869
8870
8871
8872
8873
8874
8875
8876
8877
8878
8879
8880
8881
8882
8883
8884
8885
8886
8887
8888
8889
8890
8891
8892
8893
8894
8895
8896
8897
8898
8899
8900
8901
8902
8903
8904
8905
8906
8907
8908
8909
8910
8911
8912
8913
8914
8915
8916
8917
8918
8919
8920
8921
8922
8923
8924
8925
8926
8927
8928
8929
8930
8931
8932
8933
8934
8935
8936
8937
8938
8939
8940
8941
8942
8943
8944
8945
8946
8947
8948
8949
8950
8951
8952
8953
8954
8955
8956
8957
8958
8959
8960
8961
8962
8963
8964
8965
8966
8967
8968
8969
8970
8971
8972
8973
8974
8975
8976
8977
8978
8979
8980
8981
8982
8983
8984
8985
8986
8987
8988
8989
8990
8991
8992
8993
8994
8995
8996
8997
8998
8999
9000
9001
9002
9003
9004
9005
9006
9007
9008
9009
9010
9011
9012
9013
9014
9015
9016
9017
9018
9019
9020
9021
9022
9023
9024
9025
9026
9027
9028
9029
9030
9031
9032
9033
9034
9035
9036
9037
9038
9039
9040
9041
9042
9043
9044
9045
9046
9047
9048
9049
9050
9051
9052
9053
9054
9055
9056
9057
9058
9059
9060
9061
9062
9063
9064
9065
9066
9067
9068
9069
9070
9071
9072
9073
9074
9075
9076
9077
9078
9079
9080
9081
9082
9083
9084
9085
9086
9087
9088
9089
9090
9091
9092
9093
9094
9095
9096
9097
9098
9099
9100
9101
9102
9103
9104
9105
9106
9107
9108
9109
9110
9111
9112
9113
9114
9115
9116
9117
9118
9119
9120
9121
9122
9123
9124
9125
9126
9127
9128
9129
9130
9131
9132
9133
9134
9135
9136
9137
9138
9139
9140
9141
9142
9143
9144
9145
9146
9147
9148
9149
9150
9151
9152
9153
9154
9155
9156
9157
9158
9159
9160
9161
9162
9163
9164
9165
9166
9167
9168
9169
9170
9171
9172
9173
9174
9175
9176
9177
9178
9179
9180
9181
9182
9183
9184
9185
9186
9187
9188
9189
9190
9191
9192
9193
9194
9195
9196
9197
9198
9199
9200
9201
9202
9203
9204
9205
9206
9207
9208
9209
9210
9211
9212
9213
9214
9215
9216
9217
9218
9219
9220
9221
9222
9223
9224
9225
9226
9227
9228
9229
9230
9231
9232
9233
9234
9235
9236
9237
9238
9239
9240
9241
9242
9243
9244
9245
9246
9247
9248
9249
9250
9251
9252
9253
9254
9255
9256
9257
9258
9259
9260
9261
9262
9263
9264
9265
9266
9267
9268
9269
9270
9271
9272
9273
9274
9275
9276
9277
9278
9279
9280
9281
9282
9283
9284
9285
9286
9287
9288
9289
9290
9291
9292
9293
9294
9295
9296
9297
9298
9299
9300
9301
9302
9303
9304
9305
9306
9307
9308
9309
9310
9311
9312
9313
9314
9315
9316
9317
9318
9319
9320
9321
9322
9323
9324
9325
9326
9327
9328
9329
9330
9331
9332
9333
9334
9335
9336
9337
9338
9339
9340
9341
9342
9343
9344
9345
9346
9347
9348
9349
9350
9351
9352
9353
9354
9355
9356
9357
9358
9359
9360
9361
9362
9363
9364
9365
9366
9367
9368
9369
9370
9371
9372
9373
9374
9375
9376
9377
9378
9379
9380
9381
9382
9383
9384
9385
9386
9387
9388
9389
9390
9391
9392
9393
9394
9395
9396
9397
9398
9399
9400
9401
9402
9403
9404
9405
9406
9407
9408
9409
9410
9411
9412
9413
9414
9415
9416
9417
9418
9419
9420
9421
9422
9423
9424
9425
9426
9427
9428
9429
9430
9431
9432
9433
9434
9435
9436
9437
9438
9439
9440
9441
9442
9443
9444
9445
9446
9447
9448
9449
9450
9451
9452
9453
9454
9455
9456
9457
9458
9459
9460
9461
9462
9463
9464
9465
9466
9467
9468
9469
9470
9471
9472
9473
9474
9475
9476
9477
9478
9479
9480
9481
9482
9483
9484
9485
9486
9487
9488
9489
9490
9491
9492
9493
9494
9495
9496
9497
9498
9499
9500
9501
9502
9503
9504
9505
9506
9507
9508
9509
9510
9511
9512
9513
9514
9515
9516
9517
9518
9519
9520
9521
9522
9523
9524
9525
9526
9527
9528
9529
9530
9531
9532
9533
9534
9535
9536
9537
9538
9539
9540
9541
9542
9543
9544
9545
9546
9547
9548
9549
9550
9551
9552
9553
9554
9555
9556
9557
9558
9559
9560
9561
9562
9563
9564
9565
9566
9567
9568
9569
9570
9571
9572
9573
9574
9575
9576
9577
9578
9579
9580
9581
9582
9583
9584
9585
9586
9587
9588
9589
9590
9591
9592
9593
9594
9595
9596
9597
9598
9599
9600
9601
9602
9603
9604
9605
9606
9607
9608
9609
9610
9611
9612
9613
9614
9615
9616
9617
9618
9619
9620
9621
9622
9623
9624
9625
9626
9627
9628
9629
9630
9631
9632
9633
9634
9635
9636
9637
9638
9639
9640
9641
9642
9643
9644
9645
9646
9647
9648
9649
9650
9651
9652
9653
9654
9655
9656
9657
9658
9659
9660
9661
9662
9663
9664
9665
9666
9667
9668
9669
9670
9671
9672
9673
9674
9675
9676
9677
9678
9679
9680
9681
9682
9683
9684
9685
9686
9687
9688
9689
9690
9691
9692
9693
9694
9695
9696
9697
9698
9699
9700
9701
9702
9703
9704
9705
9706
9707
9708
9709
9710
9711
9712
9713
9714
9715
9716
9717
9718
9719
9720
9721
9722
9723
9724
9725
9726
9727
9728
9729
9730
9731
9732
9733
9734
9735
9736
9737
9738
9739
9740
9741
9742
9743
9744
9745
9746
9747
9748
9749
9750
9751
9752
9753
9754
9755
9756
9757
9758
9759
9760
9761
9762
9763
9764
9765
9766
9767
9768
9769
9770
9771
9772
9773
9774
9775
9776
9777
9778
9779
9780
9781
9782
9783
9784
9785
9786
9787
9788
9789
9790
9791
9792
9793
9794
9795
9796
9797
9798
9799
9800
9801
9802
9803
9804
9805
9806
9807
9808
9809
9810
9811
9812
9813
9814
9815
9816
9817
9818
9819
9820
9821
9822
9823
9824
9825
9826
9827
9828
9829
9830
9831
9832
9833
9834
9835
9836
9837
9838
9839
9840
9841
9842
9843
9844
9845
9846
9847
9848
9849
9850
9851
9852
9853
9854
9855
9856
9857
9858
9859
9860
9861
9862
9863
9864
9865
9866
9867
9868
9869
9870
9871
9872
9873
9874
9875
9876
9877
9878
9879
9880
9881
9882
9883
9884
9885
9886
9887
9888
9889
9890
9891
9892
9893
9894
9895
9896
9897
9898
9899
9900
9901
9902
9903
9904
9905
9906
9907
9908
9909
9910
9911
9912
9913
9914
9915
9916
9917
9918
9919
9920
9921
9922
9923
9924
9925
9926
9927
9928
9929
9930
9931
9932
9933
9934
9935
9936
9937
9938
9939
9940
9941
9942
9943
9944
9945
9946
9947
9948
9949
9950
9951
9952
9953
9954
9955
9956
9957
9958
9959
9960
9961
9962
9963
9964
9965
9966
9967
9968
9969
9970
9971
9972
9973
9974
9975
9976
9977
9978
9979
9980
9981
9982
9983
9984
9985
9986
9987
9988
9989
9990
9991
9992
9993
9994
9995
9996
9997
9998
9999
10000
10001
10002
10003
10004
10005
10006
10007
10008
10009
10010
10011
10012
10013
10014
10015
10016
10017
10018
10019
10020
10021
10022
10023
10024
10025
10026
10027
10028
10029
10030
10031
10032
10033
10034
10035
10036
10037
10038
10039
10040
10041
10042
10043
10044
10045
10046
10047
10048
10049
10050
10051
10052
10053
10054
10055
10056
10057
10058
10059
10060
10061
10062
10063
10064
10065
10066
10067
10068
10069
10070
10071
10072
10073
10074
10075
10076
10077
10078
10079
10080
10081
10082
10083
10084
10085
10086
10087
10088
10089
10090
10091
10092
10093
10094
10095
10096
10097
10098
10099
10100
10101
10102
10103
10104
10105
10106
10107
10108
10109
10110
10111
10112
10113
10114
10115
10116
10117
10118
10119
10120
10121
10122
10123
10124
10125
10126
10127
10128
10129
10130
10131
10132
10133
10134
10135
10136
10137
10138
10139
10140
10141
10142
10143
10144
10145
10146
10147
10148
10149
10150
10151
10152
10153
10154
10155
10156
10157
10158
10159
10160
10161
10162
10163
10164
10165
10166
10167
10168
10169
10170
10171
10172
10173
10174
10175
10176
10177
10178
10179
10180
10181
10182
10183
10184
10185
10186
10187
10188
10189
10190
10191
10192
10193
10194
10195
10196
10197
10198
10199
10200
10201
10202
10203
10204
10205
10206
10207
10208
10209
10210
10211
10212
10213
10214
10215
10216
10217
10218
10219
10220
10221
10222
10223
10224
10225
10226
10227
10228
10229
10230
10231
10232
10233
10234
10235
10236
10237
10238
10239
10240
10241
10242
10243
10244
10245
10246
10247
10248
10249
10250
10251
10252
10253
10254
10255
10256
10257
10258
10259
10260
10261
10262
10263
10264
10265
10266
10267
10268
10269
10270
10271
10272
10273
10274
10275
10276
10277
10278
10279
10280
10281
10282
10283
10284
10285
10286
10287
10288
10289
10290
10291
10292
10293
10294
10295
10296
10297
10298
10299
10300
10301
10302
10303
10304
10305
10306
10307
10308
10309
10310
10311
10312
10313
10314
10315
10316
10317
10318
10319
10320
10321
10322
10323
10324
10325
10326
10327
10328
10329
10330
10331
10332
10333
10334
10335
10336
10337
10338
10339
10340
10341
10342
10343
10344
10345
10346
10347
10348
10349
10350
10351
10352
10353
10354
10355
10356
10357
10358
10359
10360
10361
10362
10363
10364
10365
10366
10367
10368
10369
10370
10371
10372
10373
10374
10375
10376
10377
10378
10379
10380
10381
10382
10383
10384
10385
10386
10387
10388
10389
10390
10391
10392
10393
10394
10395
10396
10397
10398
10399
10400
10401
10402
10403
10404
10405
10406
10407
10408
10409
10410
10411
10412
10413
10414
10415
10416
10417
10418
10419
10420
10421
10422
10423
10424
10425
10426
10427
10428
10429
10430
10431
10432
10433
10434
10435
10436
10437
10438
10439
10440
10441
10442
10443
10444
10445
10446
10447
10448
10449
10450
10451
10452
10453
10454
10455
10456
10457
10458
10459
10460
10461
10462
10463
10464
10465
10466
10467
10468
10469
10470
10471
10472
10473
10474
10475
10476
10477
10478
10479
10480
10481
10482
10483
10484
10485
10486
10487
10488
10489
10490
10491
10492
10493
10494
10495
10496
10497
10498
10499
10500
10501
10502
10503
10504
10505
10506
10507
10508
10509
10510
10511
10512
10513
10514
10515
10516
10517
10518
10519
10520
10521
10522
10523
10524
10525
10526
10527
10528
10529
10530
10531
10532
10533
10534
10535
10536
10537
10538
10539
10540
10541
10542
10543
10544
10545
10546
10547
10548
10549
10550
10551
10552
10553
10554
10555
10556
10557
10558
10559
10560
10561
10562
10563
10564
10565
10566
10567
10568
10569
10570
10571
10572
10573
10574
10575
10576
10577
10578
10579
10580
10581
10582
10583
10584
10585
10586
10587
10588
10589
10590
10591
10592
10593
10594
10595
10596
10597
10598
10599
10600
10601
10602
10603
10604
10605
10606
10607
10608
10609
10610
10611
10612
10613
10614
10615
10616
10617
10618
10619
10620
10621
10622
10623
10624
10625
10626
10627
10628
10629
10630
10631
10632
10633
10634
10635
10636
10637
10638
10639
10640
10641
10642
10643
10644
10645
10646
10647
10648
10649
10650
10651
10652
10653
10654
10655
10656
10657
10658
10659
10660
10661
10662
10663
10664
10665
10666
10667
10668
10669
10670
10671
10672
10673
10674
10675
10676
10677
10678
10679
10680
10681
10682
10683
10684
10685
10686
10687
10688
10689
10690
10691
10692
10693
10694
10695
10696
10697
10698
10699
10700
10701
10702
10703
10704
10705
10706
10707
10708
10709
10710
10711
10712
10713
10714
10715
10716
10717
10718
10719
10720
10721
10722
10723
10724
10725
10726
10727
10728
10729
10730
10731
10732
10733
10734
10735
10736
10737
10738
10739
10740
10741
10742
10743
10744
10745
10746
10747
10748
10749
10750
10751
10752
10753
10754
10755
10756
10757
10758
10759
10760
10761
10762
10763
10764
10765
10766
10767
10768
10769
10770
10771
10772
10773
10774
10775
10776
10777
10778
10779
10780
10781
10782
10783
10784
10785
10786
10787
10788
10789
10790
10791
10792
10793
10794
10795
10796
10797
10798
10799
10800
10801
10802
10803
10804
10805
10806
10807
10808
10809
10810
10811
10812
10813
10814
10815
10816
10817
10818
10819
10820
10821
10822
10823
10824
10825
10826
10827
10828
10829
10830
10831
10832
10833
10834
10835
10836
10837
10838
10839
10840
10841
10842
10843
10844
10845
10846
10847
10848
10849
10850
10851
10852
10853
10854
10855
10856
10857
10858
10859
10860
10861
10862
10863
10864
10865
10866
10867
10868
10869
10870
10871
10872
10873
10874
10875
10876
10877
10878
10879
10880
10881
10882
10883
10884
10885
10886
10887
10888
10889
10890
10891
10892
10893
10894
10895
10896
10897
10898
10899
10900
10901
10902
10903
10904
10905
10906
10907
10908
10909
10910
10911
10912
10913
10914
10915
10916
10917
10918
10919
10920
10921
10922
10923
10924
10925
10926
10927
10928
10929
10930
10931
10932
10933
10934
10935
10936
10937
10938
10939
10940
10941
10942
10943
10944
10945
10946
10947
10948
10949
10950
10951
10952
10953
10954
10955
10956
10957
10958
10959
10960
10961
10962
10963
10964
10965
10966
10967
10968
10969
10970
10971
10972
10973
10974
10975
10976
10977
10978
10979
10980
10981
10982
10983
10984
10985
10986
10987
10988
10989
10990
10991
10992
10993
10994
10995
10996
10997
10998
10999
11000
11001
11002
11003
11004
11005
11006
11007
11008
11009
11010
11011
11012
11013
11014
11015
11016
11017
11018
11019
11020
11021
11022
11023
11024
11025
11026
11027
11028
11029
11030
11031
11032
11033
11034
11035
11036
11037
11038
11039
11040
11041
11042
11043
11044
11045
11046
11047
11048
11049
11050
11051
11052
11053
11054
11055
11056
11057
11058
11059
11060
11061
11062
11063
11064
11065
11066
11067
11068
11069
11070
11071
11072
11073
11074
11075
11076
11077
11078
11079
11080
11081
11082
11083
11084
11085
11086
11087
11088
11089
11090
11091
11092
11093
11094
11095
11096
11097
11098
11099
11100
11101
11102
11103
11104
11105
11106
11107
11108
11109
11110
11111
11112
11113
11114
11115
11116
11117
11118
11119
11120
11121
11122
11123
11124
11125
11126
11127
11128
11129
11130
11131
11132
11133
11134
11135
11136
11137
11138
11139
11140
11141
11142
11143
11144
11145
11146
11147
11148
11149
11150
11151
11152
11153
11154
11155
11156
11157
11158
11159
11160
11161
11162
11163
11164
11165
11166
11167
11168
11169
11170
11171
11172
11173
11174
11175
11176
11177
11178
11179
11180
11181
11182
11183
11184
11185
11186
11187
11188
11189
11190
11191
11192
11193
11194
11195
11196
11197
11198
11199
11200
11201
11202
11203
11204
11205
11206
11207
11208
11209
11210
11211
11212
11213
11214
11215
11216
11217
11218
11219
11220
11221
11222
11223
11224
11225
11226
11227
11228
11229
11230
11231
11232
11233
11234
11235
11236
11237
11238
11239
11240
11241
11242
11243
11244
11245
11246
11247
11248
11249
11250
11251
11252
11253
11254
11255
11256
11257
11258
11259
11260
11261
11262
11263
11264
11265
11266
11267
11268
11269
11270
11271
11272
11273
11274
11275
11276
11277
11278
11279
11280
11281
11282
11283
11284
11285
11286
11287
11288
11289
11290
11291
11292
11293
11294
11295
11296
11297
11298
11299
11300
11301
11302
11303
11304
11305
11306
11307
11308
11309
11310
11311
11312
11313
11314
11315
11316
11317
11318
11319
11320
11321
11322
11323
11324
11325
11326
11327
11328
11329
11330
11331
11332
11333
11334
11335
11336
11337
11338
11339
11340
11341
11342
11343
11344
11345
11346
11347
11348
11349
11350
11351
11352
11353
11354
11355
11356
11357
11358
11359
11360
11361
11362
11363
11364
11365
11366
11367
11368
11369
11370
11371
11372
11373
11374
11375
11376
11377
11378
11379
11380
11381
11382
11383
11384
11385
11386
11387
11388
11389
11390
11391
11392
11393
11394
11395
11396
11397
11398
11399
11400
11401
11402
11403
11404
11405
11406
11407
11408
11409
11410
11411
11412
11413
11414
11415
11416
11417
11418
11419
11420
11421
11422
11423
11424
11425
11426
11427
11428
11429
11430
11431
11432
11433
11434
11435
11436
11437
11438
11439
11440
11441
11442
11443
11444
11445
11446
11447
11448
11449
11450
11451
11452
11453
11454
11455
11456
11457
11458
11459
11460
11461
11462
11463
11464
11465
11466
11467
11468
11469
11470
11471
11472
11473
11474
11475
11476
11477
11478
11479
11480
11481
11482
11483
11484
11485
11486
11487
11488
11489
11490
11491
11492
11493
11494
11495
11496
11497
11498
11499
11500
11501
11502
11503
11504
11505
11506
11507
11508
11509
11510
11511
11512
11513
11514
11515
11516
11517
11518
11519
11520
11521
11522
11523
11524
11525
11526
11527
11528
11529
11530
11531
11532
11533
11534
11535
11536
11537
11538
11539
11540
11541
11542
11543
11544
11545
11546
11547
11548
11549
11550
11551
11552
11553
11554
11555
11556
11557
11558
11559
11560
11561
11562
11563
11564
11565
11566
11567
11568
11569
11570
11571
11572
11573
11574
11575
11576
11577
11578
11579
11580
11581
11582
11583
11584
11585
11586
11587
11588
11589
11590
11591
11592
11593
11594
11595
11596
11597
11598
11599
11600
11601
11602
11603
11604
11605
11606
11607
11608
11609
11610
11611
11612
11613
11614
11615
11616
11617
11618
11619
11620
11621
11622
11623
11624
11625
11626
11627
11628
11629
11630
11631
11632
11633
11634
11635
11636
11637
11638
11639
11640
11641
11642
11643
11644
11645
11646
11647
11648
11649
11650
11651
11652
11653
11654
11655
11656
11657
11658
11659
11660
11661
11662
11663
11664
11665
11666
11667
11668
11669
11670
11671
11672
11673
11674
11675
11676
11677
11678
11679
11680
11681
11682
11683
11684
11685
11686
11687
11688
11689
11690
11691
11692
11693
11694
11695
11696
11697
11698
11699
11700
11701
11702
11703
11704
11705
11706
11707
11708
11709
11710
11711
11712
11713
11714
11715
11716
11717
11718
11719
11720
11721
11722
11723
11724
11725
11726
11727
11728
11729
11730
11731
11732
11733
11734
11735
<!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='extendpoky'>

<title>Common Tasks</title>
    <para>
        This chapter describes fundamental procedures such as creating layers,
        adding new software packages, extending or customizing images,
        porting work to new hardware (adding a new machine), and so forth.
        You will find that the procedures documented here occur often in the
        development cycle using the Yocto Project.
    </para>

    <section id="understanding-and-creating-layers">
        <title>Understanding and Creating Layers</title>

        <para>
            The OpenEmbedded build system supports organizing
            <ulink url='&YOCTO_DOCS_REF_URL;#metadata'>Metadata</ulink> into
            multiple layers.
            Layers allow you to isolate different types of customizations from
            each other.
            You might find it tempting to keep everything in one layer when
            working on a single project.
            However, the more modular your Metadata, the easier
            it is to cope with future changes.
        </para>

        <para>
            To illustrate how layers are used to keep things modular, consider
            machine customizations.
            These types of customizations typically reside in a special layer,
            rather than a general layer, called a Board Support Package (BSP)
            Layer.
            Furthermore, the machine customizations should be isolated from
            recipes and Metadata that support a new GUI environment,
            for example.
            This situation gives you a couple of layers: one for the machine
            configurations, and one for the GUI environment.
            It is important to understand, however, that the BSP layer can
            still make machine-specific additions to recipes within the GUI
            environment layer without polluting the GUI layer itself
            with those machine-specific changes.
            You can accomplish this through a recipe that is a BitBake append
            (<filename>.bbappend</filename>) file, which is described later
            in this section.
            <note>
                For general information on BSP layer structure, see the
                <ulink url='&YOCTO_DOCS_BSP_URL;#bsp'>Board Support Packages (BSP) - Developer's Guide</ulink>.
            </note>
        </para>

        <para>
        </para>

        <section id='yocto-project-layers'>
            <title>Layers</title>

            <para>
                The <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
                contains both general layers and BSP
                layers right out of the box.
                You can easily identify layers that ship with a
                Yocto Project release in the Source Directory by their
                folder names.
                Folders that represent layers typically have names that begin with
                the string <filename>meta-</filename>.
                <note>
                    It is not a requirement that a layer name begin with the
                    prefix <filename>meta-</filename>, but it is a commonly
                    accepted standard in the Yocto Project community.
                </note>
                For example, when you set up the Source Directory structure,
                you will see several layers:
                <filename>meta</filename>,
                <filename>meta-skeleton</filename>,
                <filename>meta-selftest</filename>,
                <filename>meta-poky</filename>, and
                <filename>meta-yocto-bsp</filename>.
                Each of these folders represents a distinct layer.
            </para>

            <para>
                As another example, if you set up a local copy of the
                <filename>meta-intel</filename> Git repository
                and then explore the folder of that general layer,
                you will discover many Intel-specific BSP layers inside.
                For more information on BSP layers, see the
                "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP Layers</ulink>"
                section in the Yocto Project Board Support Package (BSP)
                Developer's Guide.
            </para>
        </section>

        <section id='creating-your-own-layer'>
            <title>Creating Your Own Layer</title>

            <para>
                It is very easy to create your own layers to use with the
                OpenEmbedded build system.
                The Yocto Project ships with scripts that speed up creating
                general layers and BSP layers.
                This section describes the steps you perform by hand to create
                a layer so that you can better understand them.
                For information about the layer-creation scripts, see the
                "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>"
                section in the Yocto Project Board Support Package (BSP)
                Developer's Guide and the
                "<link linkend='creating-a-general-layer-using-the-yocto-layer-script'>Creating a General Layer Using the yocto-layer Script</link>"
                section further down in this manual.
            </para>

            <para>
                Follow these general steps to create your layer without the aid of a script:
                <orderedlist>
                    <listitem><para><emphasis>Check Existing Layers:</emphasis>
                        Before creating a new layer, you should be sure someone
                        has not already created a layer containing the Metadata
                        you need.
                        You can see the
                        <ulink url='http://layers.openembedded.org/layerindex/layers/'><filename>OpenEmbedded Metadata Index</filename></ulink>
                        for a list of layers from the OpenEmbedded community
                        that can be used in the Yocto Project.
                        </para></listitem>
                    <listitem><para><emphasis>Create a Directory:</emphasis>
                        Create the directory for your layer.
                        While not strictly required, prepend the name of the
                        folder with the string <filename>meta-</filename>.
                        For example:
                        <literallayout class='monospaced'>
     meta-mylayer
     meta-GUI_xyz
     meta-mymachine
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Create a Layer Configuration
                       File:</emphasis>
                       Inside your new layer folder, you need to create a
                       <filename>conf/layer.conf</filename> file.
                       It is easiest to take an existing layer configuration
                       file and copy that to your layer's
                       <filename>conf</filename> directory and then modify the
                       file as needed.</para>
                       <para>The
                       <filename>meta-yocto-bsp/conf/layer.conf</filename> file
                       demonstrates the required syntax:
                       <literallayout class='monospaced'>
     # We have a conf and classes directory, add to BBPATH
     BBPATH .= ":${LAYERDIR}"

     # We have recipes-* directories, add to BBFILES
     BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
                 ${LAYERDIR}/recipes-*/*/*.bbappend"

     BBFILE_COLLECTIONS += "yoctobsp"
     BBFILE_PATTERN_yoctobsp = "^${LAYERDIR}/"
     BBFILE_PRIORITY_yoctobsp = "5"
     LAYERVERSION_yoctobsp = "3"
                        </literallayout></para>
                        <para>Here is an explanation of the example:
                        <itemizedlist>
                            <listitem><para>The configuration and
                                classes directory is appended to
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-BBPATH'><filename>BBPATH</filename></ulink>.
                                <note>
                                    All non-distro layers, which include all BSP
                                    layers, are expected to append the layer
                                    directory to the
                                    <filename>BBPATH</filename>.
                                    On the other hand, distro layers, such as
                                    <filename>meta-poky</filename>, can choose
                                    to enforce their own precedence over
                                    <filename>BBPATH</filename>.
                                    For an example of that syntax, see the
                                    <filename>layer.conf</filename> file for
                                    the <filename>meta-poky</filename> layer.
                                </note></para></listitem>
                            <listitem><para>The recipes for the layers are
                                appended to
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILES'>BBFILES</ulink></filename>.
                                </para></listitem>
                            <listitem><para>The
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILE_COLLECTIONS'>BBFILE_COLLECTIONS</ulink></filename>
                                variable is then appended with the layer name.
                                </para></listitem>
                            <listitem><para>The
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILE_PATTERN'>BBFILE_PATTERN</ulink></filename>
                                variable is set to a regular expression and is
                                used to match files from
                                <filename>BBFILES</filename> into a particular
                                layer.
                                In this case,
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LAYERDIR'>LAYERDIR</ulink></filename>
                                is used to make <filename>BBFILE_PATTERN</filename> match within the
                                layer's path.</para></listitem>
                            <listitem><para>The
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILE_PRIORITY'>BBFILE_PRIORITY</ulink></filename>
                                variable then assigns a priority to the layer.
                                Applying priorities is useful in situations
                                where the same recipe might appear in multiple
                                layers and allows you to choose the layer
                                that takes precedence.</para></listitem>
                            <listitem><para>The
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LAYERVERSION'>LAYERVERSION</ulink></filename>
                                variable optionally specifies the version of a
                                layer as a single number.</para></listitem>
                        </itemizedlist></para>
                        <para>Note the use of the
                        <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LAYERDIR'>LAYERDIR</ulink></filename>
                        variable, which expands to the directory of the current
                        layer.</para>
                        <para>Through the use of the <filename>BBPATH</filename>
                        variable, BitBake locates class files
                        (<filename>.bbclass</filename>),
                        configuration files, and files that are included
                        with <filename>include</filename> and
                        <filename>require</filename> statements.
                        For these cases, BitBake uses the first file that
                        matches the name found in <filename>BBPATH</filename>.
                        This is similar to the way the <filename>PATH</filename>
                        variable is used for binaries.
                        It is recommended, therefore, that you use unique
                        class and configuration
                        filenames in your custom layer.</para></listitem>
                    <listitem><para><emphasis>Add Content:</emphasis> Depending
                        on the type of layer, add the content.
                        If the layer adds support for a machine, add the machine
                        configuration in a <filename>conf/machine/</filename>
                        file within the layer.
                        If the layer adds distro policy, add the distro
                        configuration in a <filename>conf/distro/</filename>
                        file within the layer.
                        If the layer introduces new recipes, put the recipes
                        you need in <filename>recipes-*</filename>
                        subdirectories within the layer.
                        <note>In order to be compliant with the Yocto Project,
                            a layer must contain a
                            <ulink url='&YOCTO_DOCS_BSP_URL;#bsp-filelayout-readme'>README file.</ulink>
                        </note>
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Optionally Test for Compatibility:</emphasis>
                        If you want permission to use the Yocto Project
                        Compatibility logo with your layer or application that
                        uses your layer, perform the steps to apply for
                        compatibility.
                        See the
                        "<link linkend='making-sure-your-layer-is-compatible-with-yocto-project'>Making Sure Your Layer is Compatible With Yocto Project</link>"
                        section for more information.
                        </para></listitem>
                </orderedlist>
            </para>
        </section>

        <section id='best-practices-to-follow-when-creating-layers'>
            <title>Following Best Practices When Creating Layers</title>

            <para>
                To create layers that are easier to maintain and that will
                not impact builds for other machines, you should consider the
                information in the following list:
                <itemizedlist>
                    <listitem><para>
                        <emphasis>Avoid "Overlaying" Entire Recipes from Other Layers in Your Configuration:</emphasis>
                        In other words, do not copy an entire recipe into your
                        layer and then modify it.
                        Rather, use an append file
                        (<filename>.bbappend</filename>) to override only those
                        parts of the original recipe you need to modify.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Avoid Duplicating Include Files:</emphasis>
                        Use append files (<filename>.bbappend</filename>)
                        for each recipe that uses an include file.
                        Or, if you are introducing a new recipe that requires
                        the included file, use the path relative to the
                        original layer directory to refer to the file.
                        For example, use
                        <filename>require recipes-core/</filename><replaceable>package</replaceable><filename>/</filename><replaceable>file</replaceable><filename>.inc</filename>
                        instead of
                        <filename>require </filename><replaceable>file</replaceable><filename>.inc</filename>.
                        If you're finding you have to overlay the include file,
                        it could indicate a deficiency in the include file in
                        the layer to which it originally belongs.
                        If this is the case, you should try to address that
                        deficiency instead of overlaying the include file.
                        For example, you could address this by getting the
                        maintainer of the include file to add a variable or
                        variables to make it easy to override the parts needing
                        to be overridden.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Structure Your Layers:</emphasis>
                        Proper use of overrides within append files and
                        placement of machine-specific files within your layer
                        can ensure that a build is not using the wrong Metadata
                        and negatively impacting a build for a different
                        machine.
                        Following are some examples:
                        <itemizedlist>
                            <listitem><para>
                                <emphasis>Modify Variables to Support a
                                Different Machine:</emphasis>
                                Suppose you have a layer named
                                <filename>meta-one</filename> that adds support
                                for building machine "one".
                                To do so, you use an append file named
                                <filename>base-files.bbappend</filename> and
                                create a dependency on "foo" by altering the
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
                                variable:
                                <literallayout class='monospaced'>
     DEPENDS = "foo"
                                </literallayout>
                                The dependency is created during any build that
                                includes the layer
                                <filename>meta-one</filename>.
                                However, you might not want this dependency
                                for all machines.
                                For example, suppose you are building for
                                machine "two" but your
                                <filename>bblayers.conf</filename> file has the
                                <filename>meta-one</filename> layer included.
                                During the build, the
                                <filename>base-files</filename> for machine
                                "two" will also have the dependency on
                                <filename>foo</filename>.</para>
                                <para>To make sure your changes apply only when
                                building machine "one", use a machine override
                                with the <filename>DEPENDS</filename> statement:
                                <literallayout class='monospaced'>
     DEPENDS_one = "foo"
                                </literallayout>
                                You should follow the same strategy when using
                                <filename>_append</filename> and
                                <filename>_prepend</filename> operations:
                                <literallayout class='monospaced'>
     DEPENDS_append_one = " foo"
     DEPENDS_prepend_one = "foo "
                                </literallayout>
                                As an actual example, here's a line from the recipe
                                for gnutls, which adds dependencies on
                                "argp-standalone" when building with the musl C
                                library:
                                <literallayout class='monospaced'>
     DEPENDS_append_libc-musl = " argp-standalone"
                                </literallayout>
                                <note>
                                    Avoiding "+=" and "=+" and using
                                    machine-specific
                                    <filename>_append</filename>
                                    and <filename>_prepend</filename> operations
                                    is recommended as well.
                                </note>
                                </para></listitem>
                            <listitem><para>
                                <emphasis>Place Machine-Specific Files in
                                Machine-Specific Locations:</emphasis>
                                When you have a base recipe, such as
                                <filename>base-files.bb</filename>, that
                                contains a
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                                statement to a file, you can use an append file
                                to cause the build to use your own version of
                                the file.
                                For example, an append file in your layer at
                                <filename>meta-one/recipes-core/base-files/base-files.bbappend</filename>
                                could extend
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESPATH'><filename>FILESPATH</filename></ulink>
                                using
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></ulink>
                                as follows:
                                <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/${BPN}:"
                                </literallayout>
                                The build for machine "one" will pick up your
                                machine-specific file as long as you have the
                                file in
                                <filename>meta-one/recipes-core/base-files/base-files/</filename>.
                                However, if you are building for a different
                                machine and the
                                <filename>bblayers.conf</filename> file includes
                                the <filename>meta-one</filename> layer and
                                the location of your machine-specific file is
                                the first location where that file is found
                                according to <filename>FILESPATH</filename>,
                                builds for all machines will also use that
                                machine-specific file.</para>
                                <para>You can make sure that a machine-specific
                                file is used for a particular machine by putting
                                the file in a subdirectory specific to the
                                machine.
                                For example, rather than placing the file in
                                <filename>meta-one/recipes-core/base-files/base-files/</filename>
                                as shown above, put it in
                                <filename>meta-one/recipes-core/base-files/base-files/one/</filename>.
                                Not only does this make sure the file is used
                                only when building for machine "one", but the
                                build process locates the file more quickly.</para>
                                <para>In summary, you need to place all files
                                referenced from <filename>SRC_URI</filename>
                                in a machine-specific subdirectory within the
                                layer in order to restrict those files to
                                machine-specific builds.
                                </para></listitem>
                        </itemizedlist>
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Perform Steps to Apply for Yocto Project Compatibility:</emphasis>
                        If you want permission to use the
                        Yocto Project Compatibility logo with your layer
                        or application that uses your layer, perform the
                        steps to apply for compatibility.
                        See the
                        "<link linkend='making-sure-your-layer-is-compatible-with-yocto-project'>Making Sure Your Layer is Compatible With Yocto Project</link>"
                        section for more information.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Follow the Layer Naming Convention:</emphasis>
                        Store custom layers in a Git repository that use the
                        <filename>meta-<replaceable>layer_name</replaceable></filename>
                        format.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Group Your Layers Locally:</emphasis>
                        Clone your repository alongside other cloned
                        <filename>meta</filename> directories from the
                        <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='making-sure-your-layer-is-compatible-with-yocto-project'>
            <title>Making Sure Your Layer is Compatible With Yocto Project</title>

            <para>
                When you create a layer used with the Yocto Project, it is
                advantageous to make sure that the layer interacts well with
                existing Yocto Project layers (i.e. the layer is compatible
                with the Yocto Project).
                Ensuring compatibility makes the layer easy to be consumed
                by others in the Yocto Project community and allows you
                permission to use the Yocto Project Compatibility logo.
            </para>

            <para>
                Version 1.0 of the Yocto Project Compatibility Program has
                been in existence for a number of releases.
                This version of the program consists of the layer application
                process that requests permission to use the Yocto Project
                Compatibility logo for your layer and application.
                You can find version 1.0 of the form at
                <ulink url='https://www.yoctoproject.org/webform/yocto-project-compatible-registration'></ulink>.
                To be granted permission to use the logo, you need to be able
                to answer "Yes" to the questions or have an acceptable
                explanation for any questions answered "No".
            </para>

            <para>
                A second version (2.0) of the Yocto Project Compatibility
                Program is currently under development.
                Included as part of version 2.0 (and currently available) is
                the <filename>yocto-compat-layer.py</filename> script.
                When run against a layer, this script tests the layer against
                tighter constraints based on experiences of how layers have
                worked in the real world and where pitfalls have been found.
            </para>

            <para>
                Part of the 2.0 version of the program that is not currently
                available but is in development is an updated compatibility
                application form.
                This updated form, among other questions, specifically
                asks if your layer has passed the test using the
                <filename>yocto-compat-layer.py</filename> script.
                <note><title>Tip</title>
                    Even though the updated application form is currently
                    unavailable for version 2.0 of the Yocto Project
                    Compatibility Program, the
                    <filename>yocto-compat-layer.py</filename> script is
                    available in OE-Core.
                    You can use the script to assess the status of your
                    layers in advance of the 2.0 release of the program.
                </note>
            </para>

            <para>
                The remainder of this section presents information on the
                version 1.0 registration form and on the
                <filename>yocto-compat-layer.py</filename> script.
            </para>

            <section id='yocto-project-compatibility-program-application'>
                <title>Yocto Project Compatibility Program Application</title>

                <para>
                    Use the 1.0 version of the form to apply for your
                    layer's compatibility approval.
                    Upon successful application, you can use the Yocto
                    Project Compatibility logo with your layer and the
                    application that uses your layer.
                </para>

                <para>
                    To access the form, use this link:
                    <ulink url='https://www.yoctoproject.org/webform/yocto-project-compatible-registration'></ulink>.
                    Follow the instructions on the form to complete your
                    application.
                </para>

                <para>
                    The application consists of the following sections:
                    <itemizedlist>
                        <listitem><para>
                            <emphasis>Contact Information:</emphasis>
                            Provide your contact information as the fields
                            require.
                            Along with your information, provide the
                            released versions of the Yocto Project for which
                            your layer is compatible.
                            </para></listitem>
                        <listitem><para>
                            <emphasis>Acceptance Criteria:</emphasis>
                            Provide "Yes" or "No" answers for each of the
                            items in the checklist.
                            Space exists at the bottom of the form for any
                            explanations for items for which you answered "No".
                            </para></listitem>
                        <listitem><para>
                            <emphasis>Recommendations:</emphasis>
                            Provide answers for the questions regarding Linux
                            kernel use and build success.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>

            <section id='yocto-compat-layer-py-script'>
                <title><filename>yocto-compat-layer.py</filename> Script</title>

                <para>
                    The <filename>yocto-compat-layer.py</filename> script,
                    which is currently available, provides you a way to
                    assess how compatible your layer is with the Yocto
                    Project.
                    You should run this script prior to using the form to
                    apply for compatibility as described in the previous
                    section.
                    <note>
                        Because the script is part of the 2.0 release of the
                        Yocto Project Compatibility Program, you are not
                        required to successfully run your layer against it
                        in order to be granted compatibility status.
                        However, it is a good idea as it promotes
                        well-behaved layers and gives you an idea of where your
                        layer stands regarding compatibility.
                    </note>
                </para>

                <para>
                    The script divides tests into three areas: COMMON, BSD,
                    and DISTRO.
                    For example, given a distribution layer (DISTRO), the
                    layer must pass both the COMMON and DISTRO related tests.
                    Furthermore, if your layer is a BSP layer, the layer must
                    pass the COMMON and BSP set of tests.
                </para>

                <para>
                    To execute the script, enter the following commands from
                    your build directory:
                    <literallayout class='monospaced'>
     $ source oe-init-build-env
     $ yocto-compat-layer.py <replaceable>your_layer_directory</replaceable>
                    </literallayout>
                    Be sure to provide the actual directory for your layer
                    as part of the command.
                </para>

                <para>
                    Entering the command causes the script to determine the
                    type of layer and then to execute a set of specific
                    tests against the layer.
                    The following list overviews the test:
                    <itemizedlist>
                        <listitem><para>
                            <filename>common.test_readme</filename>:
                            Tests if a <filename>README</filename> file
                            exists in the layer and the file is not empty.
                            </para></listitem>
                        <listitem><para>
                            <filename>common.test_parse</filename>:
                            Tests to make sure that BitBake can parse the
                            files without error (i.e.
                            <filename>bitbake -p</filename>).
                            </para></listitem>
                        <listitem><para>
                            <filename>common.test_show_environment</filename>:
                            Tests that the global or per-recipe environment
                            is in order without errors (i.e.
                            <filename>bitbake -e</filename>).
                            </para></listitem>
                        <listitem><para>
                            <filename>common.test_signatures</filename>:
                            Tests to be sure that BSP and DISTRO layers do not
                            come with recipes that change signatures.
                            </para></listitem>
                        <listitem><para>
                            <filename>bsp.test_bsp_defines_machines</filename>:
                            Tests if a BSP layer has machine configurations.
                            </para></listitem>
                        <listitem><para>
                            <filename>bsp.test_bsp_no_set_machine</filename>:
                            Tests to ensure a BSP layer does not set the
                            machine when the layer is added.
                            </para></listitem>
                        <listitem><para>
                            <filename>distro.test_distro_defines_distros</filename>:
                            Tests if a DISTRO layer has distro configurations.
                            </para></listitem>
                        <listitem><para>
                            <filename>distro.test_distro_no_set_distro</filename>:
                            Tests to ensure a DISTRO layer does not set the
                            distribution when the layer is added.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>
        </section>

        <section id='enabling-your-layer'>
            <title>Enabling Your Layer</title>

            <para>
                Before the OpenEmbedded build system can use your new layer,
                you need to enable it.
                To enable your layer, simply add your layer's path to the
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BBLAYERS'>BBLAYERS</ulink></filename>
                variable in your <filename>conf/bblayers.conf</filename> file,
                which is found in the
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
                The following example shows how to enable a layer named
                <filename>meta-mylayer</filename>:
                <literallayout class='monospaced'>
     LCONF_VERSION = "6"

     BBPATH = "${TOPDIR}"
     BBFILES ?= ""

     BBLAYERS ?= " \
       $HOME/poky/meta \
       $HOME/poky/meta-poky \
       $HOME/poky/meta-yocto-bsp \
       $HOME/poky/meta-mylayer \
       "
                </literallayout>
            </para>

            <para>
                BitBake parses each <filename>conf/layer.conf</filename> file
                as specified in the <filename>BBLAYERS</filename> variable
                within the <filename>conf/bblayers.conf</filename> file.
                During the processing of each
                <filename>conf/layer.conf</filename> file, BitBake adds the
                recipes, classes and configurations contained within the
                particular layer to the source directory.
            </para>
        </section>

        <section id='using-bbappend-files'>
            <title>Using .bbappend Files in Your Layer</title>

            <para>
                A recipe that appends Metadata to another recipe is called a
                BitBake append file.
                A BitBake append file uses the <filename>.bbappend</filename>
                file type suffix, while the corresponding recipe to which
                Metadata is being appended uses the <filename>.bb</filename>
                file type suffix.
            </para>

            <para>
                You can use a <filename>.bbappend</filename> file in your
                layer to make additions or changes to the content of another
                layer's recipe without having to copy the other layer's
                recipe into your layer.
                Your <filename>.bbappend</filename> file resides in your layer,
                while the main <filename>.bb</filename> recipe file to
                which you are appending Metadata resides in a different layer.
            </para>

            <para>
                Being able to append information to an existing recipe not only
                avoids duplication, but also automatically applies recipe
                changes from a different layer into your layer.
                If you were copying recipes, you would have to manually merge
                changes as they occur.
            </para>

            <para>
                When you create an append file, you must use the same root
                name as the corresponding recipe file.
                For example, the append file
                <filename>someapp_&DISTRO;.bbappend</filename> must apply to
                <filename>someapp_&DISTRO;.bb</filename>.
                This means the original recipe and append file names are
                version number-specific.
                If the corresponding recipe is renamed to update to a newer
                version, you must also rename and possibly update
                the corresponding <filename>.bbappend</filename> as well.
                During the build process, BitBake displays an error on starting
                if it detects a <filename>.bbappend</filename> file that does
                not have a corresponding recipe with a matching name.
                See the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-BB_DANGLINGAPPENDS_WARNONLY'><filename>BB_DANGLINGAPPENDS_WARNONLY</filename></ulink>
                variable for information on how to handle this error.
            </para>

            <para>
                As an example, consider the main formfactor recipe and a
                corresponding formfactor append file both from the
                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
                Here is the main formfactor recipe, which is named
                <filename>formfactor_0.0.bb</filename> and located in the
                "meta" layer at
                <filename>meta/recipes-bsp/formfactor</filename>:
                <literallayout class='monospaced'>
     SUMMARY = "Device formfactor information"
     SECTION = "base"
     LICENSE = "MIT"
     LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
     PR = "r45"

     SRC_URI = "file://config file://machconfig"
     S = "${WORKDIR}"

     PACKAGE_ARCH = "${MACHINE_ARCH}"
     INHIBIT_DEFAULT_DEPS = "1"

     do_install() {
	     # Install file only if it has contents
             install -d ${D}${sysconfdir}/formfactor/
             install -m 0644 ${S}/config ${D}${sysconfdir}/formfactor/
	     if [ -s "${S}/machconfig" ]; then
	             install -m 0644 ${S}/machconfig ${D}${sysconfdir}/formfactor/
	     fi
     }                </literallayout>
                In the main recipe, note the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                variable, which tells the OpenEmbedded build system where to
                find files during the build.
            </para>

            <para>
                Following is the append file, which is named
                <filename>formfactor_0.0.bbappend</filename> and is from the
                Raspberry Pi BSP Layer named
                <filename>meta-raspberrypi</filename>.
                The file is in the layer at
                <filename>recipes-bsp/formfactor</filename>:
                <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
                </literallayout>
            </para>

            <para>
                By default, the build system uses the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESPATH'><filename>FILESPATH</filename></ulink>
                variable to locate files.
                This append file extends the locations by setting the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></ulink>
                variable.
                Setting this variable in the <filename>.bbappend</filename>
                file is the most reliable and recommended method for adding
                directories to the search path used by the build system
                to find files.
            </para>

            <para>
                The statement in this example extends the directories to
                include
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-THISDIR'><filename>THISDIR</filename></ulink><filename>}/${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink><filename>}</filename>,
                which resolves to a directory named
                <filename>formfactor</filename> in the same directory
                in which the append file resides (i.e.
                <filename>meta-raspberrypi/recipes-bsp/formfactor</filename>.
                This implies that you must have the supporting directory
                structure set up that will contain any files or patches you
                will be including from the layer.
            </para>

            <para>
                Using the immediate expansion assignment operator
                <filename>:=</filename> is important because of the reference
                to <filename>THISDIR</filename>.
                The trailing colon character is important as it ensures that
                items in the list remain colon-separated.
                <note>
                    <para>
                        BitBake automatically defines the
                        <filename>THISDIR</filename> variable.
                        You should never set this variable yourself.
                        Using "_prepend" as part of the
                        <filename>FILESEXTRAPATHS</filename> ensures your path
                        will be searched prior to other paths in the final
                        list.
                    </para>

                    <para>
                        Also, not all append files add extra files.
                        Many append files simply exist to add build options
                        (e.g. <filename>systemd</filename>).
                        For these cases, your append file would not even
                        use the <filename>FILESEXTRAPATHS</filename> statement.
                    </para>
                </note>
            </para>
        </section>

        <section id='prioritizing-your-layer'>
            <title>Prioritizing Your Layer</title>

            <para>
                Each layer is assigned a priority value.
                Priority values control which layer takes precedence if there
                are recipe files with the same name in multiple layers.
                For these cases, the recipe file from the layer with a higher
                priority number takes precedence.
                Priority values also affect the order in which multiple
                <filename>.bbappend</filename> files for the same recipe are
                applied.
                You can either specify the priority manually, or allow the
                build system to calculate it based on the layer's dependencies.
            </para>

            <para>
                To specify the layer's priority manually, use the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILE_PRIORITY'><filename>BBFILE_PRIORITY</filename></ulink>
                variable.
                For example:
                <literallayout class='monospaced'>
     BBFILE_PRIORITY_mylayer = "1"
                </literallayout>
            </para>

            <note>
                <para>It is possible for a recipe with a lower version number
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>
                in a layer that has a higher priority to take precedence.</para>
                <para>Also, the layer priority does not currently affect the
                precedence order of <filename>.conf</filename>
                or <filename>.bbclass</filename> files.
                Future versions of BitBake might address this.</para>
            </note>
        </section>

        <section id='managing-layers'>
            <title>Managing Layers</title>

            <para>
                You can use the BitBake layer management tool to provide a view
                into the structure of recipes across a multi-layer project.
                Being able to generate output that reports on configured layers
                with their paths and priorities and on
                <filename>.bbappend</filename> files and their applicable
                recipes can help to reveal potential problems.
            </para>

            <para>
                Use the following form when running the layer management tool.
                <literallayout class='monospaced'>
     $ bitbake-layers <replaceable>command</replaceable> [<replaceable>arguments</replaceable>]
                </literallayout>
                The following list describes the available commands:
                <itemizedlist>
                    <listitem><para><filename><emphasis>help:</emphasis></filename>
                        Displays general help or help on a specified command.
                        </para></listitem>
                    <listitem><para><filename><emphasis>show-layers:</emphasis></filename>
                        Shows the current configured layers.
                        </para></listitem>
                    <listitem><para><filename><emphasis>show-recipes:</emphasis></filename>
                        Lists available recipes and the layers that provide them.
                        </para></listitem>
                    <listitem><para><filename><emphasis>show-overlayed:</emphasis></filename>
                        Lists overlayed recipes.
                        A recipe is overlayed when a recipe with the same name
                        exists in another layer that has a higher layer
                        priority.
                        </para></listitem>
                    <listitem><para><filename><emphasis>show-appends:</emphasis></filename>
                        Lists <filename>.bbappend</filename> files and the
                        recipe files to which they apply.
                        </para></listitem>
                    <listitem><para><filename><emphasis>show-cross-depends:</emphasis></filename>
                        Lists dependency relationships between recipes that
                        cross layer boundaries.
                        </para></listitem>
                    <listitem><para><filename><emphasis>add-layer:</emphasis></filename>
                        Adds a layer to <filename>bblayers.conf</filename>.
                        </para></listitem>
                    <listitem><para><filename><emphasis>remove-layer:</emphasis></filename>
                        Removes a layer from <filename>bblayers.conf</filename>
                        </para></listitem>
                    <listitem><para><filename><emphasis>flatten:</emphasis></filename>
                        Flattens the layer configuration into a separate output
                        directory.
                        Flattening your layer configuration builds a "flattened"
                        directory that contains the contents of all layers,
                        with any overlayed recipes removed and any
                        <filename>.bbappend</filename> files appended to the
                        corresponding recipes.
                        You might have to perform some manual cleanup of the
                        flattened layer as follows:
                        <itemizedlist>
                            <listitem><para>Non-recipe files (such as patches)
                                are overwritten.
                                The flatten command shows a warning for these
                                files.
                                </para></listitem>
                            <listitem><para>Anything beyond the normal layer
                                setup has been added to the
                                <filename>layer.conf</filename> file.
                                Only the lowest priority layer's
                                <filename>layer.conf</filename> is used.
                                </para></listitem>
                            <listitem><para>Overridden and appended items from
                                <filename>.bbappend</filename> files need to be
                                cleaned up.
                                The contents of each
                                <filename>.bbappend</filename> end up in the
                                flattened recipe.
                                However, if there are appended or changed
                                variable values, you need to tidy these up
                                yourself.
                                Consider the following example.
                                Here, the <filename>bitbake-layers</filename>
                                command adds the line
                                <filename>#### bbappended ...</filename> so that
                                you know where the following lines originate:
                                <literallayout class='monospaced'>
     ...
     DESCRIPTION = "A useful utility"
     ...
     EXTRA_OECONF = "--enable-something"
     ...

     #### bbappended from meta-anotherlayer ####

     DESCRIPTION = "Customized utility"
     EXTRA_OECONF += "--enable-somethingelse"
                                </literallayout>
                                Ideally, you would tidy up these utilities as
                                follows:
                                <literallayout class='monospaced'>
     ...
     DESCRIPTION = "Customized utility"
     ...
     EXTRA_OECONF = "--enable-something --enable-somethingelse"
     ...
                                </literallayout></para></listitem>
                        </itemizedlist></para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='creating-a-general-layer-using-the-yocto-layer-script'>
            <title>Creating a General Layer Using the yocto-layer Script</title>

            <para>
                The <filename>yocto-layer</filename> script simplifies
                creating a new general layer.
                <note>
                    For information on BSP layers, see the
                    "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP Layers</ulink>"
                    section in the Yocto Project Board Specific (BSP)
                    Developer's Guide.
                </note>
                The default mode of the script's operation is to prompt you for
                information needed to generate the layer:
                <itemizedlist>
                    <listitem><para>The layer priority.
                        </para></listitem>
                    <listitem><para>Whether or not to create a sample recipe.
                        </para></listitem>
                    <listitem><para>Whether or not to create a sample
                        append file.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                Use the <filename>yocto-layer create</filename> sub-command
                to create a new general layer.
                In its simplest form, you can create a layer as follows:
                <literallayout class='monospaced'>
     $ yocto-layer create mylayer
                </literallayout>
                The previous example creates a layer named
                <filename>meta-mylayer</filename> in the current directory.
            </para>

            <para>
                As the <filename>yocto-layer create</filename> command runs,
                default values for the prompts appear in brackets.
                Pressing enter without supplying anything for the prompts
                or pressing enter and providing an invalid response causes the
                script to accept the default value.
                Once the script completes, the new layer
                is created in the current working directory.
                The script names the layer by prepending
                <filename>meta-</filename> to the name you provide.
            </para>

            <para>
                Minimally, the script creates the following within the layer:
                <itemizedlist>
                    <listitem><para><emphasis>The <filename>conf</filename>
                        directory:</emphasis>
                        This directory contains the layer's configuration file.
                        The root name for the file is the same as the root name
                        your provided for the layer (e.g.
                        <filename><replaceable>layer</replaceable>.conf</filename>).
                        </para></listitem>
                    <listitem><para><emphasis>The
                        <filename>COPYING.MIT</filename> file:</emphasis>
                        The copyright and use notice for the software.
                        </para></listitem>
                    <listitem><para><emphasis>The <filename>README</filename>
                        file:</emphasis>
                        A file describing the contents of your new layer.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                If you choose to generate a sample recipe file, the script
                prompts you for the name for the recipe and then creates it
                in <filename><replaceable>layer</replaceable>/recipes-example/example/</filename>.
                The script creates a <filename>.bb</filename> file and a
                directory, which contains a sample
                <filename>helloworld.c</filename> source file, along with
                a sample patch file.
                If you do not provide a recipe name, the script uses
                "example".
            </para>

            <para>
                If you choose to generate a sample append file, the script
                prompts you for the name for the file and then creates it
                in <filename><replaceable>layer</replaceable>/recipes-example-bbappend/example-bbappend/</filename>.
                The script creates a <filename>.bbappend</filename> file and a
                directory, which contains a sample patch file.
                If you do not provide a recipe name, the script uses
                "example".
                The script also prompts you for the version of the append file.
                The version should match the recipe to which the append file
                is associated.
            </para>

            <para>
                The easiest way to see how the <filename>yocto-layer</filename>
                script works is to experiment with the script.
                You can also read the usage information by entering the
                following:
                <literallayout class='monospaced'>
     $ yocto-layer help
                </literallayout>
            </para>

            <para>
                Once you create your general layer, you must add it to your
                <filename>bblayers.conf</filename> file.
                Here is an example where a layer named
                <filename>meta-mylayer</filename> is added:
                <literallayout class='monospaced'>
     BBLAYERS = ?" \
        /usr/local/src/yocto/meta \
        /usr/local/src/yocto/meta-poky \
        /usr/local/src/yocto/meta-yocto-bsp \
        /usr/local/src/yocto/meta-mylayer \
        "
                </literallayout>
                Adding the layer to this file enables the build system to
                locate the layer during the build.
                </para>
        </section>
    </section>

    <section id='usingpoky-extend-customimage'>
        <title>Customizing Images</title>

        <para>
            You can customize images to satisfy particular requirements.
            This section describes several methods and provides guidelines for each.
        </para>

        <section id='usingpoky-extend-customimage-localconf'>
            <title>Customizing Images Using <filename>local.conf</filename></title>

            <para>
                Probably the easiest way to customize an image is to add a
                package by way of the <filename>local.conf</filename>
                configuration file.
                Because it is limited to local use, this method generally only
                allows you to add packages and is not as flexible as creating
                your own customized image.
                When you add packages using local variables this way, you need
                to realize that these variable changes are in effect for every
                build and consequently affect all images, which might not
                be what you require.
            </para>

            <para>
                To add a package to your image using the local configuration
                file, use the
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'>IMAGE_INSTALL</ulink></filename>
                variable with the <filename>_append</filename> operator:
                <literallayout class='monospaced'>
     IMAGE_INSTALL_append = " strace"
                </literallayout>
                Use of the syntax is important - specifically, the space between
                the quote and the package name, which is
                <filename>strace</filename> in this example.
                This space is required since the <filename>_append</filename>
                operator does not add the space.
            </para>

            <para>
                Furthermore, you must use <filename>_append</filename> instead
                of the <filename>+=</filename> operator if you want to avoid
                ordering issues.
                The reason for this is because doing so unconditionally appends
                to the variable and avoids ordering problems due to the
                variable being set in image recipes and
                <filename>.bbclass</filename> files with operators like
                <filename>?=</filename>.
                Using <filename>_append</filename> ensures the operation takes
                affect.
            </para>

            <para>
                As shown in its simplest use,
                <filename>IMAGE_INSTALL_append</filename> affects all images.
                It is possible to extend the syntax so that the variable
                applies to a specific image only.
                Here is an example:
                <literallayout class='monospaced'>
     IMAGE_INSTALL_append_pn-core-image-minimal = " strace"
                </literallayout>
                This example adds <filename>strace</filename> to the
                <filename>core-image-minimal</filename> image only.
            </para>

            <para>
                You can add packages using a similar approach through the
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-CORE_IMAGE_EXTRA_INSTALL'>CORE_IMAGE_EXTRA_INSTALL</ulink></filename>
                variable.
                If you use this variable, only
                <filename>core-image-*</filename> images are affected.
            </para>
        </section>

        <section id='usingpoky-extend-customimage-imagefeatures'>
            <title>Customizing Images Using Custom <filename>IMAGE_FEATURES</filename> and
                <filename>EXTRA_IMAGE_FEATURES</filename></title>

            <para>
                Another method for customizing your image is to enable or
                disable high-level image features by using the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></ulink>
                and <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_IMAGE_FEATURES'><filename>EXTRA_IMAGE_FEATURES</filename></ulink>
                variables.
                Although the functions for both variables are nearly equivalent,
                best practices dictate using <filename>IMAGE_FEATURES</filename>
                from within a recipe and using
                <filename>EXTRA_IMAGE_FEATURES</filename> from within
                your <filename>local.conf</filename> file, which is found in the
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
            </para>

            <para>
                To understand how these features work, the best reference is
                <filename>meta/classes/core-image.bbclass</filename>.
                This class lists out the available
                <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></ulink>
                of which most map to package groups while some, such as
                <filename>debug-tweaks</filename> and
                <filename>read-only-rootfs</filename>, resolve as general
                configuration settings.
            </para>

            <para>
                In summary, the file looks at the contents of the
                <filename>IMAGE_FEATURES</filename> variable and then maps
                or configures the feature accordingly.
                Based on this information, the build system automatically
                adds the appropriate packages or configurations to the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></ulink>
                variable.
                Effectively, you are enabling extra features by extending the
                class or creating a custom class for use with specialized image
                <filename>.bb</filename> files.
            </para>

            <para>
                Use the <filename>EXTRA_IMAGE_FEATURES</filename> variable
                from within your local configuration file.
                Using a separate area from which to enable features with
                this variable helps you avoid overwriting the features in the
                image recipe that are enabled with
                <filename>IMAGE_FEATURES</filename>.
                The value of <filename>EXTRA_IMAGE_FEATURES</filename> is added
                to <filename>IMAGE_FEATURES</filename> within
                <filename>meta/conf/bitbake.conf</filename>.
            </para>

            <para>
                To illustrate how you can use these variables to modify your
                image, consider an example that selects the SSH server.
                The Yocto Project ships with two SSH servers you can use
                with your images: Dropbear and OpenSSH.
                Dropbear is a minimal SSH server appropriate for
                resource-constrained environments, while OpenSSH is a
                well-known standard SSH server implementation.
                By default, the <filename>core-image-sato</filename> image
                is configured to use Dropbear.
                The <filename>core-image-full-cmdline</filename> and
                <filename>core-image-lsb</filename> images both
                include OpenSSH.
                The <filename>core-image-minimal</filename> image does not
                contain an SSH server.
            </para>

            <para>
                You can customize your image and change these defaults.
                Edit the <filename>IMAGE_FEATURES</filename> variable
                in your recipe or use the
                <filename>EXTRA_IMAGE_FEATURES</filename> in your
                <filename>local.conf</filename> file so that it configures the
                image you are working with to include
                <filename>ssh-server-dropbear</filename> or
                <filename>ssh-server-openssh</filename>.
            </para>

            <note>
                See the
                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>"
                section in the Yocto Project Reference Manual for a complete
                list of image features that ship with the Yocto Project.
            </note>
        </section>

        <section id='usingpoky-extend-customimage-custombb'>
            <title>Customizing Images Using Custom .bb Files</title>

            <para>
                You can also customize an image by creating a custom recipe
                that defines additional software as part of the image.
                The following example shows the form for the two lines you need:
                <literallayout class='monospaced'>
     IMAGE_INSTALL = "packagegroup-core-x11-base package1 package2"

     inherit core-image
                </literallayout>
            </para>

            <para>
                Defining the software using a custom recipe gives you total
                control over the contents of the image.
                It is important to use the correct names of packages in the
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'>IMAGE_INSTALL</ulink></filename>
                variable.
                You must use the OpenEmbedded notation and not the Debian notation for the names
                (e.g. <filename>glibc-dev</filename> instead of <filename>libc6-dev</filename>).
            </para>

            <para>
                The other method for creating a custom image is to base it on an existing image.
                For example, if you want to create an image based on <filename>core-image-sato</filename>
                but add the additional package <filename>strace</filename> to the image,
                copy the <filename>meta/recipes-sato/images/core-image-sato.bb</filename> to a
                new <filename>.bb</filename> and add the following line to the end of the copy:
                <literallayout class='monospaced'>
     IMAGE_INSTALL += "strace"
                </literallayout>
            </para>
        </section>

        <section id='usingpoky-extend-customimage-customtasks'>
            <title>Customizing Images Using Custom Package Groups</title>

            <para>
                For complex custom images, the best approach for customizing
                an image is to create a custom package group recipe that is
                used to build the image or images.
                A good example of a package group recipe is
                <filename>meta/recipes-core/packagegroups/packagegroup-base.bb</filename>.
            </para>

            <para>
                If you examine that recipe, you see that the
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'>PACKAGES</ulink></filename>
                variable lists the package group packages to produce.
                The <filename>inherit packagegroup</filename> statement
                sets appropriate default values and automatically adds
                <filename>-dev</filename>, <filename>-dbg</filename>, and
                <filename>-ptest</filename> complementary packages for each
                package specified in the <filename>PACKAGES</filename>
                statement.
                <note>
                    The <filename>inherit packages</filename> should be
                    located near the top of the recipe, certainly before
                    the <filename>PACKAGES</filename> statement.
                </note>
            </para>

            <para>
                For each package you specify in <filename>PACKAGES</filename>,
                you can use
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'>RDEPENDS</ulink></filename>
                and
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-RRECOMMENDS'>RRECOMMENDS</ulink></filename>
                entries to provide a list of packages the parent task package
                should contain.
                You can see examples of these further down in the
                <filename>packagegroup-base.bb</filename> recipe.
            </para>

            <para>
                Here is a short, fabricated example showing the same basic
                pieces:
                <literallayout class='monospaced'>
     DESCRIPTION = "My Custom Package Groups"

     inherit packagegroup

     PACKAGES = "\
         packagegroup-custom-apps \
         packagegroup-custom-tools \
         "

     RDEPENDS_packagegroup-custom-apps = "\
         dropbear \
         portmap \
         psplash"

     RDEPENDS_packagegroup-custom-tools = "\
         oprofile \
         oprofileui-server \
         lttng-tools"

     RRECOMMENDS_packagegroup-custom-tools = "\
         kernel-module-oprofile"
                </literallayout>
            </para>

            <para>
                In the previous example, two package group packages are created with their dependencies and their
                recommended package dependencies listed: <filename>packagegroup-custom-apps</filename>, and
                <filename>packagegroup-custom-tools</filename>.
                To build an image using these package group packages, you need to add
                <filename>packagegroup-custom-apps</filename> and/or
                <filename>packagegroup-custom-tools</filename> to
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'>IMAGE_INSTALL</ulink></filename>.
                For other forms of image dependencies see the other areas of this section.
            </para>
        </section>

        <section id='usingpoky-extend-customimage-image-name'>
            <title>Customizing an Image Hostname</title>

            <para>
                By default, the configured hostname (i.e.
                <filename>/etc/hostname</filename>) in an image is the
                same as the machine name.
                For example, if
                <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
                equals "qemux86", the configured hostname written to
                <filename>/etc/hostname</filename> is "qemux86".
            </para>

            <para>
                You can customize this name by altering the value of the
                "hostname" variable in the
                <filename>base-files</filename> recipe using either
                an append file or a configuration file.
                Use the following in an append file:
                <literallayout class='monospaced'>
     hostname="myhostname"
                </literallayout>
                Use the following in a configuration file:
                <literallayout class='monospaced'>
     hostname_pn-base-files = "myhostname"
                </literallayout>
            </para>

            <para>
                Changing the default value of the variable "hostname" can be
                useful in certain situations.
                For example, suppose you need to do extensive testing on an
                image and you would like to easily identify the image
                under test from existing images with typical default
                hostnames.
                In this situation, you could change the default hostname to
                "testme", which results in all the images using the name
                "testme".
                Once testing is complete and you do not need to rebuild the
                image for test any longer, you can easily reset the default
                hostname.
            </para>

            <para>
                Another point of interest is that if you unset the variable,
                the image will have no default hostname in the filesystem.
                Here is an example that unsets the variable in a
                configuration file:
                <literallayout class='monospaced'>
     hostname_pn-base-files = ""
                </literallayout>
                Having no default hostname in the filesystem is suitable for
                environments that use dynamic hostnames such as virtual
                machines.
            </para>
        </section>
    </section>

    <section id='new-recipe-writing-a-new-recipe'>
        <title>Writing a New Recipe</title>

        <para>
            Recipes (<filename>.bb</filename> files) are fundamental components
            in the Yocto Project environment.
            Each software component built by the OpenEmbedded build system
            requires a recipe to define the component.
            This section describes how to create, write, and test a new
            recipe.
            <note>
                For information on variables that are useful for recipes and
                for information about recipe naming issues, see the
                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-varlocality-recipe-required'>Required</ulink>"
                section of the Yocto Project Reference Manual.
            </note>
        </para>

        <section id='new-recipe-overview'>
            <title>Overview</title>

            <para>
                The following figure shows the basic process for creating a
                new recipe.
                The remainder of the section provides details for the steps.
                <imagedata fileref="figures/recipe-workflow.png" width="6in" depth="7in" align="center" scalefit="1" />
            </para>
        </section>

        <section id='new-recipe-locate-or-automatically-create-a-base-recipe'>
            <title>Locate or Automatically Create a Base Recipe</title>

            <para>
                You can always write a recipe from scratch.
                However, three choices exist that can help you quickly get a
                start on a new recipe:
                <itemizedlist>
                    <listitem><para>
                        <emphasis><filename>devtool add</filename>:</emphasis>
                        A command that assists in creating a recipe and
                        an environment conducive to development.
                        </para></listitem>
                    <listitem><para>
                        <emphasis><filename>recipetool create</filename>:</emphasis>
                        A command provided by the Yocto Project that automates
                        creation of a base recipe based on the source
                        files.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Existing Recipes:</emphasis>
                        Location and modification of an existing recipe that is
                        similar in function to the recipe you need.
                        </para></listitem>
                </itemizedlist>
                <note>
                    For information on recipe syntax, see the
                    "<ulink url='&YOCTO_DOCS_REF_URL;#recipe-syntax'>Recipe Syntax</ulink>"
                    section in the Yocto Project Reference Manual.
                </note>
            </para>

            <section id='new-recipe-creating-the-base-recipe-using-devtool'>
                <title>Creating the Base Recipe Using <filename>devtool add</filename></title>

                <para>
                    The <filename>devtool add</filename> command uses the same
                    logic for auto-creating the recipe as
                    <filename>recipetool create</filename>, which is listed
                    below.
                    Additionally, however, <filename>devtool add</filename>
                    sets up an environment that makes it easy for you to
                    patch the source and to make changes to the recipe as
                    is often necessary when adding a recipe to build a new
                    piece of software to be included in a build.
                </para>

                <para>
                    You can find a complete description of the
                    <filename>devtool add</filename> command in the
                    "<ulink url='&YOCTO_DOCS_SDK_URL;#sdk-a-closer-look-at-devtool-add'>A Closer Look at <filename>devtool</filename> add</ulink>"
                    section in the Yocto Project Software Development Kit
                    (SDK) Developer's Guide.
                </para>
            </section>

            <section id='new-recipe-creating-the-base-recipe-using-recipetool'>
                <title>Creating the Base Recipe Using <filename>recipetool create</filename></title>

                <para>
                    <filename>recipetool create</filename> automates creation
                    of a base recipe given a set of source code files.
                    As long as you can extract or point to the source files,
                    the tool will construct a recipe and automatically
                    configure all pre-build information into the recipe.
                    For example, suppose you have an application that builds
                    using Autotools.
                    Creating the base recipe using
                    <filename>recipetool</filename> results in a recipe
                    that has the pre-build dependencies, license requirements,
                    and checksums configured.
                </para>

                <para>
                    To run the tool, you just need to be in your
                    <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
                    and have sourced the build environment setup script
                    (i.e.
                    <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>oe-init-build-env</filename></ulink>
                    or
                    <ulink url='&YOCTO_DOCS_REF_URL;#structure-memres-core-script'><filename>oe-init-build-env-memres</filename></ulink>).
                    Here is the basic <filename>recipetool</filename> syntax:
                    <note>
                        Running <filename>recipetool -h</filename> or
                        <filename>recipetool create -h</filename> produces the
                        Python-generated help, which presented differently
                        than what follows here.
                    </note>
                    <literallayout class='monospaced'>
     recipetool -h
     recipetool create [-h]
     recipetool [-d] [-q] [--color auto | always | never ] create -o <replaceable>OUTFILE</replaceable> [-m] [-x <replaceable>EXTERNALSRC</replaceable>] <replaceable>source</replaceable>

          -d       Enables debug output.
          -q       Outputs only errors (quiet mode).
          --color  Colorizes the output automatically, always, or never.
          -h       Displays Python generated syntax for recipetool.
          create   Causes recipetool to create a base recipe.  The create
                   command is further defined with these options:

                   -o <replaceable>OUTFILE</replaceable>      Specifies the full path and filename for the generated
                                   recipe.
                   -m              Causes the recipe to be machine-specific rather than
                                   architecture-specific (default).
                   -x <replaceable>EXTERNALSRC</replaceable>  Fetches and extracts source files from <replaceable>source</replaceable>
                                   and places them in <replaceable>EXTERNALSRC</replaceable>.
                                   <replaceable>source</replaceable> must be a URL.
                   -h              Displays Python-generated syntax for create.
                   <replaceable>source</replaceable>          Specifies the source code on which to base the
                                   recipe.
                    </literallayout>
                </para>

                <para>
                    Running <filename>recipetool create -o</filename>&nbsp;<replaceable>OUTFILE</replaceable>
                    creates the base recipe and locates it properly in the
                    layer that contains your source files.
                    Following are some syntax examples:
                </para>

                <para>
                    Use this syntax to generate a recipe based on <replaceable>source</replaceable>.
                    Once generated, the recipe resides in the existing source
                    code layer:
                    <literallayout class='monospaced'>
     recipetool create -o <replaceable>OUTFILE</replaceable>&nbsp;<replaceable>source</replaceable>
                    </literallayout>
                    Use this syntax to generate a recipe using code that you
                    extract from <replaceable>source</replaceable>.
                    The extracted code is placed in its own layer defined
                    by <replaceable>EXTERNALSRC</replaceable>.
                    <literallayout class='monospaced'>
     recipetool create -o <replaceable>OUTFILE</replaceable> -x <replaceable>EXTERNALSRC</replaceable> <replaceable>source</replaceable>
                    </literallayout>
                    Use this syntax to generate a recipe based on <replaceable>source</replaceable>.
                    The options direct <filename>recipetool</filename> to
                    generate debugging information.
                    Once generated, the recipe resides in the existing source
                    code layer:
                    <literallayout class='monospaced'>
     recipetool create -d -o <replaceable>OUTFILE</replaceable> <replaceable>source</replaceable>
                    </literallayout>
                </para>
            </section>

            <section id='new-recipe-locating-and-using-a-similar-recipe'>
                <title>Locating and Using a Similar Recipe</title>

                <para>
                    Before writing a recipe from scratch, it is often useful to
                    discover whether someone else has already written one that
                    meets (or comes close to meeting) your needs.
                    The Yocto Project and OpenEmbedded communities maintain many
                    recipes that might be candidates for what you are doing.
                    You can find a good central index of these recipes in the
                    <ulink url='http://layers.openembedded.org'>OpenEmbedded metadata index</ulink>.
                </para>

                <para>
                    Working from an existing recipe or a skeleton recipe is the
                    best way to get started.
                    Here are some points on both methods:
                    <itemizedlist>
                        <listitem><para><emphasis>Locate and modify a recipe that
                            is close to what you want to do:</emphasis>
                            This method works when you are familiar with the
                            current recipe space.
                            The method does not work so well for those new to
                            the Yocto Project or writing recipes.</para>
                            <para>Some risks associated with this method are
                            using a recipe that has areas totally unrelated to
                            what you are trying to accomplish with your recipe,
                            not recognizing areas of the recipe that you might
                            have to add from scratch, and so forth.
                            All these risks stem from unfamiliarity with the
                            existing recipe space.</para></listitem>
                        <listitem><para><emphasis>Use and modify the following
                            skeleton recipe:</emphasis>
                            If for some reason you do not want to use
                            <filename>recipetool</filename> and you cannot
                            find an existing recipe that is close to meeting
                            your needs, you can use the following structure to
                            provide the fundamental areas of a new recipe.
                            <literallayout class='monospaced'>
     DESCRIPTION = ""
     HOMEPAGE = ""
     LICENSE = ""
     SECTION = ""
     DEPENDS = ""
     LIC_FILES_CHKSUM = ""

     SRC_URI = ""
                            </literallayout>
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>
        </section>

        <section id='new-recipe-storing-and-naming-the-recipe'>
            <title>Storing and Naming the Recipe</title>

            <para>
                Once you have your base recipe, you should put it in your
                own layer and name it appropriately.
                Locating it correctly ensures that the OpenEmbedded build
                system can find it when you use BitBake to process the
                recipe.
            </para>

            <itemizedlist>
                <listitem><para><emphasis>Storing Your Recipe:</emphasis>
                    The OpenEmbedded build system locates your recipe
                    through the layer's <filename>conf/layer.conf</filename>
                    file and the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILES'><filename>BBFILES</filename></ulink>
                    variable.
                    This variable sets up a path from which the build system can
                    locate recipes.
                    Here is the typical use:
                    <literallayout class='monospaced'>
     BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
                 ${LAYERDIR}/recipes-*/*/*.bbappend"
                    </literallayout>
                    Consequently, you need to be sure you locate your new recipe
                    inside your layer such that it can be found.</para>
                    <para>You can find more information on how layers are
                    structured in the
                    "<link linkend='understanding-and-creating-layers'>Understanding and Creating Layers</link>"
                    section.</para></listitem>
                <listitem><para><emphasis>Naming Your Recipe:</emphasis>
                    When you name your recipe, you need to follow this naming
                    convention:
                    <literallayout class='monospaced'>
     <replaceable>basename</replaceable>_<replaceable>version</replaceable>.bb
                    </literallayout>
                    Use lower-cased characters and do not include the reserved
                    suffixes <filename>-native</filename>,
                    <filename>-cross</filename>, <filename>-initial</filename>,
                    or <filename>-dev</filename> casually (i.e. do not use them
                    as part of your recipe name unless the string applies).
                    Here are some examples:
                    <literallayout class='monospaced'>
     cups_1.7.0.bb
     gawk_4.0.2.bb
     irssi_0.8.16-rc1.bb
                    </literallayout></para></listitem>
            </itemizedlist>
        </section>

        <section id='new-recipe-running-a-build-on-the-recipe'>
            <title>Running a Build on the Recipe</title>

            <para>
                Creating a new recipe is usually an iterative process that
                requires using BitBake to process the recipe multiple times in
                order to progressively discover and add information to the
                recipe file.
            </para>

            <para>
                Assuming you have sourced a build environment setup script (i.e.
                <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink>
                or
                <ulink url='&YOCTO_DOCS_REF_URL;#structure-memres-core-script'><filename>oe-init-build-env-memres</filename></ulink>)
                and you are in the
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>,
                use BitBake to process your recipe.
                All you need to provide is the
                <filename><replaceable>basename</replaceable></filename> of the recipe as described
                in the previous section:
                <literallayout class='monospaced'>
     $ bitbake <replaceable>basename</replaceable>
                </literallayout>

            </para>

            <para>
                During the build, the OpenEmbedded build system creates a
                temporary work directory for each recipe
                (<filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}</filename>)
                where it keeps extracted source files, log files, intermediate
                compilation and packaging files, and so forth.
            </para>

            <para>
                The path to the per-recipe temporary work directory depends
                on the context in which it is being built.
                The quickest way to find this path is to have BitBake return it
                by running the following:
                <literallayout class='monospaced'>
     $ bitbake -e <replaceable>basename</replaceable> | grep ^WORKDIR=
                </literallayout>
                As an example, assume a Source Directory top-level folder named
                <filename>poky</filename>, a default Build Directory at
                <filename>poky/build</filename>, and a
                <filename>qemux86-poky-linux</filename> machine target system.
                Furthermore, suppose your recipe is named
                <filename>foo_1.3.0.bb</filename>.
                In this case, the work directory the build system uses to
                build the package would be as follows:
                <literallayout class='monospaced'>
     poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
                </literallayout>
                Inside this directory you can find sub-directories such as
                <filename>image</filename>, <filename>packages-split</filename>,
                and <filename>temp</filename>.
                After the build, you can examine these to determine how well
                the build went.
                <note>
                    You can find log files for each task in the recipe's
                    <filename>temp</filename> directory (e.g.
                    <filename>poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0/temp</filename>).
                    Log files are named <filename>log.<replaceable>taskname</replaceable></filename>
                    (e.g. <filename>log.do_configure</filename>,
                    <filename>log.do_fetch</filename>, and
                    <filename>log.do_compile</filename>).
                </note>
            </para>

            <para>
                You can find more information about the build process in
                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-development-environment'>The Yocto Project Development Environment</ulink>"
                chapter of the Yocto Project Reference Manual.
            </para>
        </section>

        <section id='new-recipe-fetching-code'>
            <title>Fetching Code</title>

            <para>
                The first thing your recipe must do is specify how to fetch
                the source files.
                Fetching is controlled mainly through the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                variable.
                Your recipe must have a <filename>SRC_URI</filename> variable
                that points to where the source is located.
                For a graphical representation of source locations, see the
                "<ulink url='&YOCTO_DOCS_REF_URL;#sources-dev-environment'>Sources</ulink>"
                section in the Yocto Project Reference Manual.
            </para>

            <para>
                The
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-fetch'><filename>do_fetch</filename></ulink>
                task uses the prefix of each entry in the
                <filename>SRC_URI</filename> variable value to determine which
                fetcher to use to get your source files.
                It is the <filename>SRC_URI</filename> variable that triggers
                the fetcher.
                The
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-patch'><filename>do_patch</filename></ulink>
                task uses the variable after source is fetched to apply
                patches.
                The OpenEmbedded build system uses
                <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESOVERRIDES'><filename>FILESOVERRIDES</filename></ulink>
                for scanning directory locations for local files in
                <filename>SRC_URI</filename>.
            </para>

            <para>
                The <filename>SRC_URI</filename> variable in your recipe must
                define each unique location for your source files.
                It is good practice to not hard-code pathnames in an URL used
                in <filename>SRC_URI</filename>.
                Rather than hard-code these paths, use
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink><filename>}</filename>,
                which causes the fetch process to use the version specified in
                the recipe filename.
                Specifying the version in this manner means that upgrading the
                recipe to a future version is as simple as renaming the recipe
                to match the new version.
            </para>

            <para>
                Here is a simple example from the
                <filename>meta/recipes-devtools/cdrtools/cdrtools-native_3.01a20.bb</filename>
                recipe where the source comes from a single tarball.
                Notice the use of the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>
                variable:
                <literallayout class='monospaced'>
     SRC_URI = "ftp://ftp.berlios.de/pub/cdrecord/alpha/cdrtools-${PV}.tar.bz2"
                </literallayout>
            </para>

            <para>
                Files mentioned in <filename>SRC_URI</filename> whose names end
                in a typical archive extension (e.g. <filename>.tar</filename>,
                <filename>.tar.gz</filename>, <filename>.tar.bz2</filename>,
                <filename>.zip</filename>, and so forth), are automatically
                extracted during the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-unpack'><filename>do_unpack</filename></ulink>
                task.
                For another example that specifies these types of files, see
                the
                "<link linkend='new-recipe-autotooled-package'>Autotooled Package</link>"
                section.
            </para>

            <para>
                Another way of specifying source is from an SCM.
                For Git repositories, you must specify
                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRCREV'><filename>SRCREV</filename></ulink>
                and you should specify
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>
                to include the revision with
                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRCPV'><filename>SRCPV</filename></ulink>.
                Here is an example from the recipe
                <filename>meta/recipes-kernel/blktrace/blktrace_git.bb</filename>:
                <literallayout class='monospaced'>
     SRCREV = "d6918c8832793b4205ed3bfede78c2f915c23385"

     PR = "r6"
     PV = "1.0.5+git${SRCPV}"

     SRC_URI = "git://git.kernel.dk/blktrace.git \
                file://ldflags.patch"
                </literallayout>
            </para>

            <para>
                If your <filename>SRC_URI</filename> statement includes
                URLs pointing to individual files fetched from a remote server
                other than a version control system, BitBake attempts to
                verify the files against checksums defined in your recipe to
                ensure they have not been tampered with or otherwise modified
                since the recipe was written.
                Two checksums are used:
                <filename>SRC_URI[md5sum]</filename> and
                <filename>SRC_URI[sha256sum]</filename>.
            </para>

            <para>
                If your <filename>SRC_URI</filename> variable points to
                more than a single URL (excluding SCM URLs), you need to
                provide the <filename>md5</filename> and
                <filename>sha256</filename> checksums for each URL.
                For these cases, you provide a name for each URL as part of
                the <filename>SRC_URI</filename> and then reference that name
                in the subsequent checksum statements.
                Here is an example:
                <literallayout class='monospaced'>
     SRC_URI = "${DEBIAN_MIRROR}/main/a/apmd/apmd_3.2.2.orig.tar.gz;name=tarball \
                ${DEBIAN_MIRROR}/main/a/apmd/apmd_${PV}.diff.gz;name=patch"

     SRC_URI[tarball.md5sum] = "b1e6309e8331e0f4e6efd311c2d97fa8"
     SRC_URI[tarball.sha256sum] = "7f7d9f60b7766b852881d40b8ff91d8e39fccb0d1d913102a5c75a2dbb52332d"

     SRC_URI[patch.md5sum] = "57e1b689264ea80f78353519eece0c92"
     SRC_URI[patch.sha256sum] = "7905ff96be93d725544d0040e425c42f9c05580db3c272f11cff75b9aa89d430"
                </literallayout>
            </para>

            <para>
                Proper values for <filename>md5</filename> and
                <filename>sha256</filename> checksums might be available
                with other signatures on the download page for the upstream
                source (e.g. <filename>md5</filename>,
                <filename>sha1</filename>, <filename>sha256</filename>,
                <filename>GPG</filename>, and so forth).
                Because the OpenEmbedded build system only deals with
                <filename>sha256sum</filename> and <filename>md5sum</filename>,
                you should verify all the signatures you find by hand.
            </para>

            <para>
                If no <filename>SRC_URI</filename> checksums are specified
                when you attempt to build the recipe, or you provide an
                incorrect checksum, the build will produce an error for each
                missing or incorrect checksum.
                As part of the error message, the build system provides
                the checksum string corresponding to the fetched file.
                Once you have the correct checksums, you can copy and paste
                them into your recipe and then run the build again to continue.
                <note>
                    As mentioned, if the upstream source provides signatures
                    for verifying the downloaded source code, you should
                    verify those manually before setting the checksum values
                    in the recipe and continuing with the build.
                </note>
            </para>

            <para>
                This final example is a bit more complicated and is from the
                <filename>meta/recipes-sato/rxvt-unicode/rxvt-unicode_9.20.bb</filename>
                recipe.
                The example's <filename>SRC_URI</filename> statement identifies
                multiple files as the source files for the recipe: a tarball, a
                patch file, a desktop file, and an icon.
                <literallayout class='monospaced'>
     SRC_URI = "http://dist.schmorp.de/rxvt-unicode/Attic/rxvt-unicode-${PV}.tar.bz2 \
                file://xwc.patch \
                file://rxvt.desktop \
                file://rxvt.png"
                </literallayout>
            </para>

            <para>
                When you specify local files using the
                <filename>file://</filename> URI protocol, the build system
                fetches files from the local machine.
                The path is relative to the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESPATH'><filename>FILESPATH</filename></ulink>
                variable and searches specific directories in a certain order:
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BP'><filename>BP</filename></ulink><filename>}</filename>,
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BPN'><filename>BPN</filename></ulink><filename>}</filename>,
                and <filename>files</filename>.
                The directories are assumed to be subdirectories of the
                directory in which the recipe or append file resides.
                For another example that specifies these types of files, see the
                "<link linkend='new-recipe-single-c-file-package-hello-world'>Single .c File Package (Hello World!)</link>"
                section.
            </para>

            <para>
                The previous example also specifies a patch file.
                Patch files are files whose names usually end in
                <filename>.patch</filename> or <filename>.diff</filename> but
                can end with compressed suffixes such as
                <filename>diff.gz</filename> and
                <filename>patch.bz2</filename>, for example.
                The build system automatically applies patches as described
                in the
                "<link linkend='new-recipe-patching-code'>Patching Code</link>" section.
            </para>
        </section>

        <section id='new-recipe-unpacking-code'>
            <title>Unpacking Code</title>

            <para>
                During the build, the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-unpack'><filename>do_unpack</filename></ulink>
                task unpacks the source with
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink><filename>}</filename>
                pointing to where it is unpacked.
            </para>

            <para>
                If you are fetching your source files from an upstream source
                archived tarball and the tarball's internal structure matches
                the common convention of a top-level subdirectory named
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BPN'><filename>BPN</filename></ulink><filename>}-${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink><filename>}</filename>,
                then you do not need to set <filename>S</filename>.
                However, if <filename>SRC_URI</filename> specifies to fetch
                source from an archive that does not use this convention,
                or from an SCM like Git or Subversion, your recipe needs to
                define <filename>S</filename>.
            </para>

            <para>
                If processing your recipe using BitBake successfully unpacks
                the source files, you need to be sure that the directory
                pointed to by <filename>${S}</filename> matches the structure
                of the source.
            </para>
        </section>

        <section id='new-recipe-patching-code'>
            <title>Patching Code</title>

            <para>
                Sometimes it is necessary to patch code after it has been
                fetched.
                Any files mentioned in <filename>SRC_URI</filename> whose
                names end in <filename>.patch</filename> or
                <filename>.diff</filename> or compressed versions of these
                suffixes (e.g. <filename>diff.gz</filename> are treated as
                patches.
                The
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-patch'><filename>do_patch</filename></ulink>
                task automatically applies these patches.
            </para>

            <para>
                The build system should be able to apply patches with the "-p1"
                option (i.e. one directory level in the path will be stripped
                off).
                If your patch needs to have more directory levels stripped off,
                specify the number of levels using the "striplevel" option in
                the <filename>SRC_URI</filename> entry for the patch.
                Alternatively, if your patch needs to be applied in a specific
                subdirectory that is not specified in the patch file, use the
                "patchdir" option in the entry.
            </para>

            <para>
                As with all local files referenced in
                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                using <filename>file://</filename>, you should place
                patch files in a directory next to the recipe either
                named the same as the base name of the recipe
                (<ulink url='&YOCTO_DOCS_REF_URL;#var-BP'><filename>BP</filename></ulink>
                and
                <ulink url='&YOCTO_DOCS_REF_URL;#var-BPN'><filename>BPN</filename></ulink>)
                or "files".
            </para>
        </section>

        <section id='new-recipe-licensing'>
            <title>Licensing</title>

            <para>
                Your recipe needs to have both the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-LICENSE'><filename>LICENSE</filename></ulink>
                and
                <ulink url='&YOCTO_DOCS_REF_URL;#var-LIC_FILES_CHKSUM'><filename>LIC_FILES_CHKSUM</filename></ulink>
                variables:
                <itemizedlist>
                    <listitem><para><emphasis><filename>LICENSE</filename>:</emphasis>
                        This variable specifies the license for the software.
                        If you do not know the license under which the software
                        you are building is distributed, you should go to the
                        source code and look for that information.
                        Typical files containing this information include
                        <filename>COPYING</filename>,
                        <filename>LICENSE</filename>, and
                        <filename>README</filename> files.
                        You could also find the information near the top of
                        a source file.
                        For example, given a piece of software licensed under
                        the GNU General Public License version 2, you would
                        set <filename>LICENSE</filename> as follows:
                        <literallayout class='monospaced'>
     LICENSE = "GPLv2"
                        </literallayout></para>
                        <para>The licenses you specify within
                        <filename>LICENSE</filename> can have any name as long
                        as you do not use spaces, since spaces are used as
                        separators between license names.
                        For standard licenses, use the names of the files in
                        <filename>meta/files/common-licenses/</filename>
                        or the <filename>SPDXLICENSEMAP</filename> flag names
                        defined in <filename>meta/conf/licenses.conf</filename>.
                        </para></listitem>
                    <listitem><para><emphasis><filename>LIC_FILES_CHKSUM</filename>:</emphasis>
                        The OpenEmbedded build system uses this variable to
                        make sure the license text has not changed.
                        If it has, the build produces an error and it affords
                        you the chance to figure it out and correct the problem.
                        </para>
                        <para>You need to specify all applicable licensing
                        files for the software.
                        At the end of the configuration step, the build process
                        will compare the checksums of the files to be sure
                        the text has not changed.
                        Any differences result in an error with the message
                        containing the current checksum.
                        For more explanation and examples of how to set the
                        <filename>LIC_FILES_CHKSUM</filename> variable, see the
                        "<ulink url='&YOCTO_DOCS_REF_URL;#usingpoky-configuring-LIC_FILES_CHKSUM'>Tracking License Changes</ulink>"
                        section in the Yocto Project Reference Manual.</para>
                        <para>To determine the correct checksum string, you
                        can list the appropriate files in the
                        <filename>LIC_FILES_CHKSUM</filename> variable with
                        incorrect md5 strings, attempt to build the software,
                        and then note the resulting error messages that will
                        report the correct md5 strings.
                        See the
                        "<link linkend='new-recipe-fetching-code'>Fetching Code</link>"
                        section for additional information.
                    </para>

                    <para>
                        Here is an example that assumes the software has a
                        <filename>COPYING</filename> file:
                        <literallayout class='monospaced'>
     LIC_FILES_CHKSUM = "file://COPYING;md5=xxx"
                        </literallayout>
                        When you try to build the software, the build system
                        will produce an error and give you the correct string
                        that you can substitute into the recipe file for a
                        subsequent build.
                        </para></listitem>
                </itemizedlist>
            </para>

<!--

            <para>
                For trying this out I created a new recipe named
                <filename>htop_1.0.2.bb</filename> and put it in
                <filename>poky/meta/recipes-extended/htop</filename>.
                There are two license type statements in my very simple
                recipe:
                <literallayout class='monospaced'>
     LICENSE = ""

     LIC_FILES_CHKSUM = ""

     SRC_URI[md5sum] = ""
     SRC_URI[sha256sum] = ""
                </literallayout>
                Evidently, you need to run a <filename>bitbake -c cleanall htop</filename>.
                Next, you delete or comment out the two <filename>SRC_URI</filename>
                lines at the end and then attempt to build the software with
                <filename>bitbake htop</filename>.
                Doing so causes BitBake to report some errors and and give
                you the actual strings you need for the last two
                <filename>SRC_URI</filename> lines.
                Prior to this, you have to dig around in the home page of the
                source for <filename>htop</filename> and determine that the
                software is released under GPLv2.
                You can provide that in the <filename>LICENSE</filename>
                statement.
                Now you edit your recipe to have those two strings for
                the <filename>SRC_URI</filename> statements:
                <literallayout class='monospaced'>
     LICENSE = "GPLv2"

     LIC_FILES_CHKSUM = ""

     SRC_URI = "${SOURCEFORGE_MIRROR}/htop/htop-${PV}.tar.gz"
     SRC_URI[md5sum] = "0d01cca8df3349c74569cefebbd9919e"
     SRC_URI[sha256sum] = "ee60657b044ece0df096c053060df7abf3cce3a568ab34d260049e6a37ccd8a1"
                </literallayout>
                At this point, you can build the software again using the
                <filename>bitbake htop</filename> command.
                There is just a set of errors now associated with the
                empty <filename>LIC_FILES_CHKSUM</filename> variable now.
            </para>
-->

        </section>

        <section id='new-dependencies'>
            <title>Dependencies</title>

            <para>
                Most software packages have a short list of other packages
                that they require, which are called dependencies.
                These dependencies fall into two main categories: build-time
                dependencies, which are required when the software is built;
                and runtime dependencies, which are required to be installed
                on the target in order for the software to run.
            </para>

            <para>
                Within a recipe, you specify build-time dependencies using the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
                variable.
                Although nuances exist, items specified in
                <filename>DEPENDS</filename> should be names of other recipes.
                It is important that you specify all build-time dependencies
                explicitly.
                If you do not, due to the parallel nature of BitBake's
                execution, you can end up with a race condition where the
                dependency is present for one task of a recipe (e.g.
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-configure'><filename>do_configure</filename></ulink>)
                and then gone when the next task runs (e.g.
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-compile'><filename>do_compile</filename></ulink>).
            </para>

            <para>
                Another consideration is that configure scripts might
                automatically check for optional dependencies and enable
                corresponding functionality if those dependencies are found.
                This behavior means that to ensure deterministic results and
                thus avoid more race conditions, you need to either explicitly
                specify these dependencies as well, or tell the configure
                script explicitly to disable the functionality.
                If you wish to make a recipe that is more generally useful
                (e.g. publish the recipe in a layer for others to use),
                instead of hard-disabling the functionality, you can use the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGECONFIG'><filename>PACKAGECONFIG</filename></ulink>
                variable to allow functionality and the corresponding
                dependencies to be enabled and disabled easily by other
                users of the recipe.
            </para>

            <para>
                Similar to build-time dependencies, you specify runtime
                dependencies through a variable -
                <ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'><filename>RDEPENDS</filename></ulink>,
                which is package-specific.
                All variables that are package-specific need to have the name
                of the package added to the end as an override.
                Since the main package for a recipe has the same name as the
                recipe, and the recipe's name can be found through the
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink><filename>}</filename>
                variable, then you specify the dependencies for the main
                package by setting <filename>RDEPENDS_${PN}</filename>.
                If the package were named <filename>${PN}-tools</filename>,
                then you would set <filename>RDEPENDS_${PN}-tools</filename>,
                and so forth.
            </para>

            <para>
                Some runtime dependencies will be set automatically at
                packaging time.
                These dependencies include any shared library dependencies
                (i.e. if a package "example" contains "libexample" and
                another package "mypackage" contains a binary that links to
                "libexample" then the OpenEmbedded build system will
                automatically add a runtime dependency to "mypackage" on
                "example").
                See the
                "<ulink url='&YOCTO_DOCS_REF_URL;#automatically-added-runtime-dependencies'>Automatically Added Runtime Dependencies</ulink>"
                in the Yocto Project Reference Manual for further details.
            </para>
        </section>

        <section id='new-recipe-configuring-the-recipe'>
            <title>Configuring the Recipe</title>

            <para>
                Most software provides some means of setting build-time
                configuration options before compilation.
                Typically, setting these options is accomplished by running a
                configure script with some options, or by modifying a build
                configuration file.
                <note>
                    As of Yocto Project Release 1.7, some of the core recipes
                    that package binary configuration scripts now disable the
                    scripts due to the scripts previously requiring error-prone
                    path substitution.
                    The OpenEmbedded build system uses
                    <filename>pkg-config</filename> now, which is much more
                    robust.
                    You can find a list of the <filename>*-config</filename>
                    scripts that are disabled list in the
                    "<ulink url='&YOCTO_DOCS_REF_URL;#migration-1.7-binary-configuration-scripts-disabled'>Binary Configuration Scripts Disabled</ulink>"
                    section in the Yocto Project Reference Manual.
                </note>
            </para>

            <para>
                A major part of build-time configuration is about checking for
                build-time dependencies and possibly enabling optional
                functionality as a result.
                You need to specify any build-time dependencies for the
                software you are building in your recipe's
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
                value, in terms of other recipes that satisfy those
                dependencies.
                You can often find build-time or runtime
                dependencies described in the software's documentation.
            </para>

            <para>
                The following list provides configuration items of note based
                on how your software is built:
                <itemizedlist>
                    <listitem><para><emphasis>Autotools:</emphasis>
                        If your source files have a
                        <filename>configure.ac</filename> file, then your
                        software is built using Autotools.
                        If this is the case, you just need to worry about
                        modifying the configuration.</para>
                        <para>When using Autotools, your recipe needs to inherit
                        the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-autotools'><filename>autotools</filename></ulink>
                        class and your recipe does not have to contain a
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-configure'><filename>do_configure</filename></ulink>
                        task.
                        However, you might still want to make some adjustments.
                        For example, you can set
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_OECONF'><filename>EXTRA_OECONF</filename></ulink>
                        or
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGECONFIG_CONFARGS'><filename>PACKAGECONFIG_CONFARGS</filename></ulink>
                        to pass any needed configure options that are specific
                        to the recipe.</para></listitem>
                    <listitem><para><emphasis>CMake:</emphasis>
                        If your source files have a
                        <filename>CMakeLists.txt</filename> file, then your
                        software is built using CMake.
                        If this is the case, you just need to worry about
                        modifying the configuration.</para>
                        <para>When you use CMake, your recipe needs to inherit
                        the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-cmake'><filename>cmake</filename></ulink>
                        class and your recipe does not have to contain a
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-configure'><filename>do_configure</filename></ulink>
                        task.
                        You can make some adjustments by setting
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_OECMAKE'><filename>EXTRA_OECMAKE</filename></ulink>
                        to pass any needed configure options that are specific
                        to the recipe.</para></listitem>
                    <listitem><para><emphasis>Other:</emphasis>
                        If your source files do not have a
                        <filename>configure.ac</filename> or
                        <filename>CMakeLists.txt</filename> file, then your
                        software is built using some method other than Autotools
                        or CMake.
                        If this is the case, you normally need to provide a
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-configure'><filename>do_configure</filename></ulink>
                        task in your recipe
                        unless, of course, there is nothing to configure.
                        </para>
                        <para>Even if your software is not being built by
                        Autotools or CMake, you still might not need to deal
                        with any configuration issues.
                        You need to determine if configuration is even a required step.
                        You might need to modify a Makefile or some configuration file
                        used for the build to specify necessary build options.
                        Or, perhaps you might need to run a provided, custom
                        configure script with the appropriate options.</para>
                        <para>For the case involving a custom configure
                        script, you would run
                        <filename>./configure --help</filename> and look for
                        the options you need to set.</para></listitem>
                </itemizedlist>
            </para>

            <para>
                Once configuration succeeds, it is always good practice to
                look at the <filename>log.do_configure</filename> file to
                ensure that the appropriate options have been enabled and no
                additional build-time dependencies need to be added to
                <filename>DEPENDS</filename>.
                For example, if the configure script reports that it found
                something not mentioned in <filename>DEPENDS</filename>, or
                that it did not find something that it needed for some
                desired optional functionality, then you would need to add
                those to <filename>DEPENDS</filename>.
                Looking at the log might also reveal items being checked for,
                enabled, or both that you do not want, or items not being found
                that are in <filename>DEPENDS</filename>, in which case
                you would need to look at passing extra options to the
                configure script as needed.
                For reference information on configure options specific to the
                software you are building, you can consult the output of the
                <filename>./configure --help</filename> command within
                <filename>${S}</filename> or consult the software's upstream
                documentation.
            </para>
        </section>

        <section id='new-recipe-using-headers-to-interface-with-devices'>
            <title>Using Headers to Interface with Devices</title>

            <para>
                If your recipe builds an application that needs to
                communicate with some device or needs an API into a custom
                kernel, you will need to provide appropriate header files.
                Under no circumstances should you ever modify the existing
                <filename>meta/recipes-kernel/linux-libc-headers/linux-libc-headers.inc</filename>
                file.
                These headers are used to build <filename>libc</filename> and
                must not be compromised with custom or machine-specific
                header information.
                If you customize <filename>libc</filename> through modified
                headers all other applications that use
                <filename>libc</filename> thus become affected.
                <note><title>Warning</title>
                    Never copy and customize the <filename>libc</filename>
                    header file (i.e.
                    <filename>meta/recipes-kernel/linux-libc-headers/linux-libc-headers.inc</filename>).
                </note>
                The correct way to interface to a device or custom kernel is
                to use a separate package that provides the additional headers
                for the driver or other unique interfaces.
                When doing so, your application also becomes responsible for
                creating a dependency on that specific provider.
            </para>

            <para>
                Consider the following:
                <itemizedlist>
                    <listitem><para>
                        Never modify
                        <filename>linux-libc-headers.inc</filename>.
                        Consider that file to be part of the
                        <filename>libc</filename> system, and not something
                        you use to access the kernel directly.
                        You should access <filename>libc</filename> through
                        specific <filename>libc</filename> calls.
                        </para></listitem>
                    <listitem><para>
                        Applications that must talk directly to devices
                        should either provide necessary headers themselves,
                        or establish a dependency on a special headers package
                        that is specific to that driver.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                For example, suppose you want to modify an existing header
                that adds I/O control or network support.
                If the modifications are used by a small number programs,
                providing a unique version of a header is easy and has little
                impact.
                When doing so, bear in mind the guidelines in the previous
                list.
                <note>
                    If for some reason your changes need to modify the behavior
                    of the <filename>libc</filename>, and subsequently all
                    other applications on the system, use a
                    <filename>.bbappend</filename> to modify the
                    <filename>linux-kernel-headers.inc</filename> file.
                    However, take care to not make the changes
                    machine specific.
                </note>
            </para>

            <para>
                Consider a case where your kernel is older and you need
                an older <filename>libc</filename> ABI.
                The headers installed by your recipe should still be a
                standard mainline kernel, not your own custom one.
            </para>

            <para>
                When you use custom kernel headers you need to get them from
                <ulink url='&YOCTO_DOCS_REF_URL;#var-STAGING_KERNEL_DIR'><filename>STAGING_KERNEL_DIR</filename></ulink>,
                which is the directory with kernel headers that are
                required to build out-of-tree modules.
                Your recipe will also need the following:
                <literallayout class='monospaced'>
     do_configure[depends] += "virtual/kernel:do_shared_workdir"
                </literallayout>
            </para>
        </section>

        <section id='new-recipe-compilation'>
            <title>Compilation</title>

            <para>
                During a build, the <filename>do_compile</filename> task
                happens after source is fetched, unpacked, and configured.
                If the recipe passes through <filename>do_compile</filename>
                successfully, nothing needs to be done.
            </para>

            <para>
                However, if the compile step fails, you need to diagnose the
                failure.
                Here are some common issues that cause failures.
                <note>
                    For cases where improper paths are detected for
                    configuration files or for when libraries/headers cannot
                    be found, be sure you are using the more robust
                    <filename>pkg-config</filename>.
                    See the note in section
                    "<link linkend='new-recipe-configuring-the-recipe'>Configuring the Recipe</link>"
                    for additional information.
                </note>
                <itemizedlist>
                    <listitem><para><emphasis>Parallel build failures:</emphasis>
                        These failures manifest themselves as intermittent
                        errors, or errors reporting that a file or directory
                        that should be created by some other part of the build
                        process could not be found.
                        This type of failure can occur even if, upon inspection,
                        the file or directory does exist after the build has
                        failed, because that part of the build process happened
                        in the wrong order.</para>
                        <para>To fix the problem, you need to either satisfy
                        the missing dependency in the Makefile or whatever
                        script produced the Makefile, or (as a workaround)
                        set
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink>
                        to an empty string:
                        <literallayout class='monospaced'>
     PARALLEL_MAKE = ""
                        </literallayout></para>
                        <para>
                            For information on parallel Makefile issues, see the
                            "<link linkend='debugging-parallel-make-races'>Debugging Parallel Make Races</link>"
                            section.
                            </para></listitem>
                    <listitem><para><emphasis>Improper host path usage:</emphasis>
                        This failure applies to recipes building for the target
                        or <filename>nativesdk</filename> only.
                        The failure occurs when the compilation process uses
                        improper headers, libraries, or other files from the
                        host system when cross-compiling for the target.
                        </para>
                        <para>To fix the problem, examine the
                        <filename>log.do_compile</filename> file to identify
                        the host paths being used (e.g.
                        <filename>/usr/include</filename>,
                        <filename>/usr/lib</filename>, and so forth) and then
                        either add configure options, apply a patch, or do both.
                        </para></listitem>
                    <listitem><para><emphasis>Failure to find required
                        libraries/headers:</emphasis>
                        If a build-time dependency is missing because it has
                        not been declared in
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>,
                        or because the dependency exists but the path used by
                        the build process to find the file is incorrect and the
                        configure step did not detect it, the compilation
                        process could fail.
                        For either of these failures, the compilation process
                        notes that files could not be found.
                        In these cases, you need to go back and add additional
                        options to the configure script as well as possibly
                        add additional build-time dependencies to
                        <filename>DEPENDS</filename>.</para>
                        <para>Occasionally, it is necessary to apply a patch
                        to the source to ensure the correct paths are used.
                        If you need to specify paths to find files staged
                        into the sysroot from other recipes, use the variables
                        that the OpenEmbedded build system provides
                        (e.g.
                        <filename>STAGING_BINDIR</filename>,
                        <filename>STAGING_INCDIR</filename>,
                        <filename>STAGING_DATADIR</filename>, and so forth).
<!--
                        (e.g.
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-STAGING_BINDIR'><filename>STAGING_BINDIR</filename></ulink>,
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-STAGING_INCDIR'><filename>STAGING_INCDIR</filename></ulink>,
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-STAGING_DATADIR'><filename>STAGING_DATADIR</filename></ulink>,
                        and so forth).
-->
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='new-recipe-installing'>
            <title>Installing</title>

            <para>
                During <filename>do_install</filename>, the task copies the
                built files along with their hierarchy to locations that
                would mirror their locations on the target device.
                The installation process copies files from the
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink><filename>}</filename>,
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-B'><filename>B</filename></ulink><filename>}</filename>,
                and
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}</filename>
                directories to the
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-D'><filename>D</filename></ulink><filename>}</filename>
                directory to create the structure as it should appear on the
                target system.
            </para>

            <para>
                How your software is built affects what you must do to be
                sure your software is installed correctly.
                The following list describes what you must do for installation
                depending on the type of build system used by the software
                being built:
                <itemizedlist>
                    <listitem><para><emphasis>Autotools and CMake:</emphasis>
                        If the software your recipe is building uses Autotools
                        or CMake, the OpenEmbedded build
                        system understands how to install the software.
                        Consequently, you do not have to have a
                        <filename>do_install</filename> task as part of your
                        recipe.
                        You just need to make sure the install portion of the
                        build completes with no issues.
                        However, if you wish to install additional files not
                        already being installed by
                        <filename>make install</filename>, you should do this
                        using a <filename>do_install_append</filename> function
                        using the install command as described in
                        the "Manual" bulleted item later in this list.
                        </para></listitem>
                    <listitem><para><emphasis>Other (using
                        <filename>make install</filename>):</emphasis>
                        You need to define a
                        <filename>do_install</filename> function in your
                        recipe.
                        The function should call
                        <filename>oe_runmake install</filename> and will likely
                        need to pass in the destination directory as well.
                        How you pass that path is dependent on how the
                        <filename>Makefile</filename> being run is written
                        (e.g. <filename>DESTDIR=${D}</filename>,
                        <filename>PREFIX=${D}</filename>,
                        <filename>INSTALLROOT=${D}</filename>, and so forth).
                        </para>
                        <para>For an example recipe using
                        <filename>make install</filename>, see the
                        "<link linkend='new-recipe-makefile-based-package'>Makefile-Based Package</link>"
                        section.</para></listitem>
                    <listitem><para><emphasis>Manual:</emphasis>
                        You need to define a
                        <filename>do_install</filename> function in your
                        recipe.
                        The function must first use
                        <filename>install -d</filename> to create the
                        directories under
                        <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-D'><filename>D</filename></ulink><filename>}</filename>.
                        Once the directories exist, your function can use
                        <filename>install</filename> to manually install the
                        built software into the directories.</para>
                        <para>You can find more information on
                        <filename>install</filename> at
                        <ulink url='http://www.gnu.org/software/coreutils/manual/html_node/install-invocation.html'></ulink>.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                For the scenarios that do not use Autotools or
                CMake, you need to track the installation
                and diagnose and fix any issues until everything installs
                correctly.
                You need to look in the default location of
                <filename>${D}</filename>, which is
                <filename>${WORKDIR}/image</filename>, to be sure your
                files have been installed correctly.
            </para>

            <note><title>Notes</title>
                <itemizedlist>
                    <listitem><para>
                        During the installation process, you might need to
                        modify some of the installed files to suit the target
                        layout.
                        For example, you might need to replace hard-coded paths
                        in an initscript with values of variables provided by
                        the build system, such as replacing
                        <filename>/usr/bin/</filename> with
                        <filename>${bindir}</filename>.
                        If you do perform such modifications during
                        <filename>do_install</filename>, be sure to modify the
                        destination file after copying rather than before
                        copying.
                        Modifying after copying ensures that the build system
                        can re-execute <filename>do_install</filename> if
                        needed.
                        </para></listitem>
                    <listitem><para>
                        <filename>oe_runmake install</filename>, which can be
                        run directly or can be run indirectly by the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-autotools'><filename>autotools</filename></ulink>
                        and
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-cmake'><filename>cmake</filename></ulink>
                        classes, runs <filename>make install</filename> in
                        parallel.
                        Sometimes, a Makefile can have missing dependencies
                        between targets that can result in race conditions.
                        If you experience intermittent failures during
                        <filename>do_install</filename>, you might be able to
                        work around them by disabling parallel Makefile
                        installs by adding the following to the recipe:
                        <literallayout class='monospaced'>
     PARALLEL_MAKEINST = ""
                        </literallayout>
                        See
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKEINST'><filename>PARALLEL_MAKEINST</filename></ulink>
                        for additional information.
                        </para></listitem>
                </itemizedlist>
            </note>
        </section>

        <section id='new-recipe-enabling-system-services'>
            <title>Enabling System Services</title>

            <para>
                If you want to install a service, which is a process that
                usually starts on boot and runs in the background, then
                you must include some additional definitions in your recipe.
            </para>

            <para>
                If you are adding services and the service initialization
                script or the service file itself is not installed, you must
                provide for that installation in your recipe using a
                <filename>do_install_append</filename> function.
                If your recipe already has a <filename>do_install</filename>
                function, update the function near its end rather than
                adding an additional <filename>do_install_append</filename>
                function.
            </para>

            <para>
                When you create the installation for your services, you need
                to accomplish what is normally done by
                <filename>make install</filename>.
                In other words, make sure your installation arranges the output
                similar to how it is arranged on the target system.
            </para>

            <para>
                The OpenEmbedded build system provides support for starting
                services two different ways:
                <itemizedlist>
                    <listitem><para><emphasis>SysVinit:</emphasis>
                        SysVinit is a system and service manager that
                        manages the init system used to control the very basic
                        functions of your system.
                        The init program is the first program
                        started by the Linux kernel when the system boots.
                        Init then controls the startup, running and shutdown
                        of all other programs.</para>
                        <para>To enable a service using SysVinit, your recipe
                        needs to inherit the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-update-rc.d'><filename>update-rc.d</filename></ulink>
                        class.
                        The class helps facilitate safely installing the
                        package on the target.</para>
                        <para>You will need to set the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-INITSCRIPT_PACKAGES'><filename>INITSCRIPT_PACKAGES</filename></ulink>,
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-INITSCRIPT_NAME'><filename>INITSCRIPT_NAME</filename></ulink>,
                        and
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-INITSCRIPT_PARAMS'><filename>INITSCRIPT_PARAMS</filename></ulink>
                        variables within your recipe.</para></listitem>
                    <listitem><para><emphasis>systemd:</emphasis>
                        System Management Daemon (systemd) was designed to
                        replace SysVinit and to provide
                        enhanced management of services.
                        For more information on systemd, see the systemd
                        homepage at
                        <ulink url='http://freedesktop.org/wiki/Software/systemd/'></ulink>.
                        </para>
                        <para>To enable a service using systemd, your recipe
                        needs to inherit the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-systemd'><filename>systemd</filename></ulink>
                        class.
                        See the <filename>systemd.bbclass</filename> file
                        located in your
                        <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
                        section for more information.
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='new-recipe-packaging'>
            <title>Packaging</title>

            <para>
                Successful packaging is a combination of automated processes
                performed by the OpenEmbedded build system and some
                specific steps you need to take.
                The following list describes the process:
                <itemizedlist>
                    <listitem><para><emphasis>Splitting Files</emphasis>:
                        The <filename>do_package</filename> task splits the
                        files produced by the recipe into logical components.
                        Even software that produces a single binary might
                        still have debug symbols, documentation, and other
                        logical components that should be split out.
                        The <filename>do_package</filename> task ensures
                        that files are split up and packaged correctly.
                        </para></listitem>
                    <listitem><para><emphasis>Running QA Checks</emphasis>:
                        The
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-insane'><filename>insane</filename></ulink>
                        class adds a step to
                        the package generation process so that output quality
                        assurance checks are generated by the OpenEmbedded
                        build system.
                        This step performs a range of checks to be sure the
                        build's output is free of common problems that show
                        up during runtime.
                        For information on these checks, see the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-insane'><filename>insane</filename></ulink>
                        class and the
                        "<ulink url='&YOCTO_DOCS_REF_URL;#ref-qa-checks'>QA Error and Warning Messages</ulink>"
                        chapter in the Yocto Project Reference Manual.
                        </para></listitem>
                    <listitem><para><emphasis>Hand-Checking Your Packages</emphasis>:
                        After you build your software, you need to be sure
                        your packages are correct.
                        Examine the
                        <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}/packages-split</filename>
                        directory and make sure files are where you expect
                        them to be.
                        If you discover problems, you can set
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'><filename>PACKAGES</filename></ulink>,
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-FILES'><filename>FILES</filename></ulink>,
                        <filename>do_install(_append)</filename>, and so forth as
                        needed.
                        </para></listitem>
                    <listitem><para><emphasis>Splitting an Application into Multiple Packages</emphasis>:
                        If you need to split an application into several
                        packages, see the
                        "<link linkend='splitting-an-application-into-multiple-packages'>Splitting an Application into Multiple Packages</link>"
                        section for an example.
                        </para></listitem>
                    <listitem><para><emphasis>Installing a Post-Installation Script</emphasis>:
                        For an example showing how to install a
                        post-installation script, see the
                        "<link linkend='new-recipe-post-installation-scripts'>Post-Installation Scripts</link>"
                        section.
                        </para></listitem>
                    <listitem><para><emphasis>Marking Package Architecture</emphasis>:
                        Depending on what your recipe is building and how it
                        is configured, it might be important to mark the
                        packages produced as being specific to a particular
                        machine, or to mark them as not being specific to
                        a particular machine or architecture at all.</para>
                        <para>By default, packages apply to any machine with the
                        same architecture as the target machine.
                        When a recipe produces packages that are
                        machine-specific (e.g. the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
                        value is passed into the configure script or a patch
                        is applied only for a particular machine), you should
                        mark them as such by adding the following to the
                        recipe:
                        <literallayout class='monospaced'>
     PACKAGE_ARCH = "${MACHINE_ARCH}"
                        </literallayout></para>
                        <para>On the other hand, if the recipe produces packages
                        that do not contain anything specific to the target
                        machine or architecture at all (e.g. recipes
                        that simply package script files or configuration
                        files), you should use the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-allarch'><filename>allarch</filename></ulink>
                        class to do this for you by adding this to your
                        recipe:
                        <literallayout class='monospaced'>
     inherit allarch
                        </literallayout>
                        Ensuring that the package architecture is correct is
                        not critical while you are doing the first few builds
                        of your recipe.
                        However, it is important in order
                        to ensure that your recipe rebuilds (or does not
                        rebuild) appropriately in response to changes in
                        configuration, and to ensure that you get the
                        appropriate packages installed on the target machine,
                        particularly if you run separate builds for more
                        than one target machine.
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='new-sharing-files-between-recipes'>
            <title>Sharing Files Between Recipes</title>

            <para>
                Recipes often need to use files provided by other recipes on
                the build host.
                For example, an application linking to a common library needs
                access to the library itself and its associated headers.
                The way this access is accomplished is by populating a sysroot
                with files.
                Each recipe has two sysroots in its work directory, one for
                target files
                (<filename>recipe-sysroot</filename>) and one for files that
                are native to the build host
                (<filename>recipe-sysroot-native</filename>).
                <note>
                    You could find the term "staging" used within the Yocto
                    project regarding files populating sysroots (e.g. the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-STAGING_DIR'><filename>STAGING_DIR</filename></ulink>
                    variable).
                </note>
            </para>

            <para>
                Recipes should never populate the sysroot directly (i.e. write
                files into sysroot).
                Instead, files should be installed into standard locations
                during the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
                task within the
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-D'><filename>D</filename></ulink><filename>}</filename>
                directory.
                The reason for this limitation is that almost all files that
                populate the sysroot are cataloged in manifests in order to
                ensure the files can be removed later when a recipe is either
                modified or removed.
                Thus, the sysroot is able to remain free from stale files.
            </para>

            <para>
                A subset of the files installed by the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
                task are used by the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-populate_sysroot'><filename>do_populate_sysroot</filename></ulink>
                task as defined by the the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-SYSROOT_DIRS'><filename>SYSROOT_DIRS</filename></ulink>
                variable to automatically populate the sysroot.
                It is possible to modify the list of directories that populate
                the sysroot.
                The following example shows how you could add the
                <filename>/opt</filename> directory to the list of
                directories within a recipe:
                <literallayout class='monospaced'>
     SYSROOT_DIRS += "/opt"
                </literallayout>
            </para>

            <para>
                For a more complete description of the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-populate_sysroot'><filename>do_populate_sysroot</filename></ulink>
                task and its associated functions, see the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-staging'><filename>staging</filename></ulink>
                class.
            </para>
        </section>

        <section id='properly-versioning-pre-release-recipes'>
            <title>Properly Versioning Pre-Release Recipes</title>

            <para>
                Sometimes the name of a recipe can lead to versioning
                problems when the recipe is upgraded to a final release.
                For example, consider the
                <filename>irssi_0.8.16-rc1.bb</filename> recipe file in
                the list of example recipes in the
                "<link linkend='new-recipe-storing-and-naming-the-recipe'>Storing and Naming the Recipe</link>"
                section.
                This recipe is at a release candidate stage (i.e.
                "rc1").
                When the recipe is released, the recipe filename becomes
                <filename>irssi_0.8.16.bb</filename>.
                The version change from <filename>0.8.16-rc1</filename>
                to <filename>0.8.16</filename> is seen as a decrease by the
                build system and package managers, so the resulting packages
                will not correctly trigger an upgrade.
            </para>

            <para>
                In order to ensure the versions compare properly, the
                recommended convention is to set
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>
                within the recipe to
                "<replaceable>previous_version</replaceable>+<replaceable>current_version</replaceable>".
                You can use an additional variable so that you can use the
                current version elsewhere.
                Here is an example:
                <literallayout class='monospaced'>
     REALPV = "0.8.16-rc1"
     PV = "0.8.15+${REALPV}"
                </literallayout>
            </para>
        </section>

        <section id='new-recipe-post-installation-scripts'>
            <title>Post-Installation Scripts</title>

            <para>
                Post-installation scripts run immediately after installing
                a package on the target or during image creation when a
                package is included in an image.
                To add a post-installation script to a package, add a
                <filename>pkg_postinst_</filename><replaceable>PACKAGENAME</replaceable><filename>()</filename> function to
                the recipe file (<filename>.bb</filename>) and replace
                <replaceable>PACKAGENAME</replaceable> with the name of the package
                you want to attach to the <filename>postinst</filename>
                script.
                To apply the post-installation script to the main package
                for the recipe, which is usually what is required, specify
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink><filename>}</filename>
                in place of <replaceable>PACKAGENAME</replaceable>.
            </para>

            <para>
                A post-installation function has the following structure:
                <literallayout class='monospaced'>
     pkg_postinst_<replaceable>PACKAGENAME</replaceable>() {
     # Commands to carry out
     }
                </literallayout>
            </para>

            <para>
                The script defined in the post-installation function is
                called when the root filesystem is created.
                If the script succeeds, the package is marked as installed.
                If the script fails, the package is marked as unpacked and
                the script is executed when the image boots again.
                <note>
                    Any RPM post-installation script that runs on the target
                    should return a 0 exit code.
                    RPM does not allow non-zero exit codes for these scripts,
                    and the RPM package manager will cause the package to fail
                    installation on the target.
                </note>
            </para>

            <para>
                Sometimes it is necessary for the execution of a
                post-installation script to be delayed until the first boot.
                For example, the script might need to be executed on the
                device itself.
                To delay script execution until boot time, use the following
                structure in the post-installation script:
                <literallayout class='monospaced'>
     pkg_postinst_<replaceable>PACKAGENAME</replaceable>() {
     if [ x"$D" = "x" ]; then
          # Actions to carry out on the device go here
     else
          exit 1
     fi
     }
                </literallayout>
            </para>

            <para>
                The previous example delays execution until the image boots
                again because the environment variable <filename>D</filename>
                points to the directory containing the image when
                the root filesystem is created at build time but is unset
                when executed on the first boot.
            </para>

            <para>
                If you have recipes that use <filename>pkg_postinst</filename>
                scripts and they require the use of non-standard native
                tools that have dependencies during rootfs construction, you
                need to use the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_WRITE_DEPS'><filename>PACKAGE_WRITE_DEPS</filename></ulink>
                variable in your recipe to list these tools.
                If you do not use this variable, the tools might be missing and
                execution of the post-installation script is deferred until
                first boot.
                Deferring the script to first boot is undesirable and for
                read-only rootfs impossible.
            </para>

            <note>
                Equivalent support for pre-install, pre-uninstall, and
                post-uninstall scripts exist by way of
                <filename>pkg_preinst</filename>,
                <filename>pkg_prerm</filename>, and
                <filename>pkg_postrm</filename>, respectively.
                These scrips work in exactly the same way as does
                <filename>pkg_postinst</filename> with the exception that they
                run at different times.
                Also, because of when they run, they are not applicable to
                being run at image creation time like
                <filename>pkg_postinst</filename>.
            </note>
        </section>

        <section id='new-recipe-testing'>
            <title>Testing</title>

            <para>
                The final step for completing your recipe is to be sure that
                the software you built runs correctly.
                To accomplish runtime testing, add the build's output
                packages to your image and test them on the target.
            </para>

            <para>
                For information on how to customize your image by adding
                specific packages, see the
                "<link linkend='usingpoky-extend-customimage'>Customizing Images</link>"
                section.
            </para>
        </section>

        <section id='new-recipe-testing-examples'>
            <title>Examples</title>

            <para>
                To help summarize how to write a recipe, this section provides
                some examples given various scenarios:
                <itemizedlist>
                    <listitem><para>Recipes that use local files</para></listitem>
                    <listitem><para>Using an Autotooled package</para></listitem>
                    <listitem><para>Using a Makefile-based package</para></listitem>
                    <listitem><para>Splitting an application into multiple packages</para></listitem>
                    <listitem><para>Adding binaries to an image</para></listitem>
                </itemizedlist>
            </para>

            <section id='new-recipe-single-c-file-package-hello-world'>
                <title>Single .c File Package (Hello World!)</title>

                <para>
                    Building an application from a single file that is stored
                    locally (e.g. under <filename>files</filename>) requires
                    a recipe that has the file listed in the
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'>SRC_URI</ulink></filename>
                    variable.
                    Additionally, you need to manually write the
                    <filename>do_compile</filename> and
                    <filename>do_install</filename> tasks.
                    The <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-S'>S</ulink></filename>
                    variable defines the directory containing the source code,
                    which is set to
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>
                    in this case - the directory BitBake uses for the build.
                    <literallayout class='monospaced'>
     SUMMARY = "Simple helloworld application"
     SECTION = "examples"
     LICENSE = "MIT"
     LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"

     SRC_URI = "file://helloworld.c"

     S = "${WORKDIR}"

     do_compile() {
     	${CC} helloworld.c -o helloworld
     }

     do_install() {
     	install -d ${D}${bindir}
     	install -m 0755 helloworld ${D}${bindir}
     }
                    </literallayout>
                </para>

                <para>
                    By default, the <filename>helloworld</filename>,
                    <filename>helloworld-dbg</filename>, and
                    <filename>helloworld-dev</filename> packages are built.
                    For information on how to customize the packaging process,
                    see the
                    "<link linkend='splitting-an-application-into-multiple-packages'>Splitting an Application into Multiple Packages</link>"
                    section.
                </para>
            </section>

            <section id='new-recipe-autotooled-package'>
                <title>Autotooled Package</title>
                <para>
                    Applications that use Autotools such as <filename>autoconf</filename> and
                    <filename>automake</filename> require a recipe that has a source archive listed in
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'>SRC_URI</ulink></filename> and
                    also inherit the
                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-autotools'><filename>autotools</filename></ulink>
                    class, which contains the definitions of all the steps
                    needed to build an Autotool-based application.
                    The result of the build is automatically packaged.
                    And, if the application uses NLS for localization, packages with local information are
                    generated (one package per language).
                    Following is one example: (<filename>hello_2.3.bb</filename>)
                    <literallayout class='monospaced'>
     SUMMARY = "GNU Helloworld application"
     SECTION = "examples"
     LICENSE = "GPLv2+"
     LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe"

     SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.gz"

     inherit autotools gettext
                     </literallayout>
                </para>

                <para>
                    The variable
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LIC_FILES_CHKSUM'>LIC_FILES_CHKSUM</ulink></filename>
                    is used to track source license changes as described in the
                    "<ulink url='&YOCTO_DOCS_REF_URL;#usingpoky-configuring-LIC_FILES_CHKSUM'>Tracking License Changes</ulink>" section.
                    You can quickly create Autotool-based recipes in a manner similar to the previous example.
                </para>
            </section>

            <section id='new-recipe-makefile-based-package'>
                <title>Makefile-Based Package</title>

                <para>
                    Applications that use GNU <filename>make</filename> also require a recipe that has
                    the source archive listed in
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'>SRC_URI</ulink></filename>.
                    You do not need to add a <filename>do_compile</filename> step since by default BitBake
                    starts the <filename>make</filename> command to compile the application.
                    If you need additional <filename>make</filename> options, you should store them in the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_OEMAKE'><filename>EXTRA_OEMAKE</filename></ulink>
                    or
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGECONFIG_CONFARGS'><filename>PACKAGECONFIG_CONFARGS</filename></ulink>
                    variables.
                    BitBake passes these options into the GNU <filename>make</filename> invocation.
                    Note that a <filename>do_install</filename> task is still required.
                    Otherwise, BitBake runs an empty <filename>do_install</filename> task by default.
                </para>

               <para>
                    Some applications might require extra parameters to be passed to the compiler.
                    For example, the application might need an additional header path.
                    You can accomplish this by adding to the
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-CFLAGS'>CFLAGS</ulink></filename> variable.
                    The following example shows this:
                    <literallayout class='monospaced'>
     CFLAGS_prepend = "-I ${S}/include "
                    </literallayout>
                </para>

                <para>
                In the following example, <filename>mtd-utils</filename> is a makefile-based package:
                    <literallayout class='monospaced'>
     SUMMARY = "Tools for managing memory technology devices"
     SECTION = "base"
     DEPENDS = "zlib lzo e2fsprogs util-linux"
     HOMEPAGE = "http://www.linux-mtd.infradead.org/"
     LICENSE = "GPLv2+"
     LIC_FILES_CHKSUM = "file://COPYING;md5=0636e73ff0215e8d672dc4c32c317bb3 \
                         file://include/common.h;beginline=1;endline=17;md5=ba05b07912a44ea2bf81ce409380049c"

     # Use the latest version at 26 Oct, 2013
     SRCREV = "9f107132a6a073cce37434ca9cda6917dd8d866b"
     SRC_URI = "git://git.infradead.org/mtd-utils.git \
                     file://add-exclusion-to-mkfs-jffs2-git-2.patch \
     "

     PV = "1.5.1+git${SRCPV}"

     S = "${WORKDIR}/git"

     EXTRA_OEMAKE = "'CC=${CC}' 'RANLIB=${RANLIB}' 'AR=${AR}' 'CFLAGS=${CFLAGS} -I${S}/include -DWITHOUT_XATTR' 'BUILDDIR=${S}'"

     do_install () {
             oe_runmake install DESTDIR=${D} SBINDIR=${sbindir} MANDIR=${mandir} INCLUDEDIR=${includedir}
     }

     PACKAGES =+ "mtd-utils-jffs2 mtd-utils-ubifs mtd-utils-misc"

     FILES_mtd-utils-jffs2 = "${sbindir}/mkfs.jffs2 ${sbindir}/jffs2dump ${sbindir}/jffs2reader ${sbindir}/sumtool"
     FILES_mtd-utils-ubifs = "${sbindir}/mkfs.ubifs ${sbindir}/ubi*"
     FILES_mtd-utils-misc = "${sbindir}/nftl* ${sbindir}/ftl* ${sbindir}/rfd* ${sbindir}/doc* ${sbindir}/serve_image ${sbindir}/recv_image"

     PARALLEL_MAKE = ""

     BBCLASSEXTEND = "native"
                    </literallayout>
                </para>
            </section>

            <section id='splitting-an-application-into-multiple-packages'>
                <title>Splitting an Application into Multiple Packages</title>

                <para>
                    You can use the variables
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'>PACKAGES</ulink></filename> and
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-FILES'>FILES</ulink></filename>
                    to split an application into multiple packages.
                </para>

                <para>
                    Following is an example that uses the <filename>libxpm</filename> recipe.
                    By default, this recipe generates a single package that contains the library along
                    with a few binaries.
                    You can modify the recipe to split the binaries into separate packages:
                    <literallayout class='monospaced'>
     require xorg-lib-common.inc

     SUMMARY = "Xpm: X Pixmap extension library"
     LICENSE = "BSD"
     LIC_FILES_CHKSUM = "file://COPYING;md5=51f4270b012ecd4ab1a164f5f4ed6cf7"
     DEPENDS += "libxext libsm libxt"
     PE = "1"

     XORG_PN = "libXpm"

     PACKAGES =+ "sxpm cxpm"
     FILES_cxpm = "${bindir}/cxpm"
     FILES_sxpm = "${bindir}/sxpm"
                    </literallayout>
                </para>

                <para>
                    In the previous example, we want to ship the <filename>sxpm</filename>
                    and <filename>cxpm</filename> binaries in separate packages.
                    Since <filename>bindir</filename> would be packaged into the main
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PN'>PN</ulink></filename>
                    package by default, we prepend the <filename>PACKAGES</filename>
                    variable so additional package names are added to the start of list.
                    This results in the extra <filename>FILES_*</filename>
                    variables then containing information that define which files and
                    directories go into which packages.
                    Files included by earlier packages are skipped by latter packages.
                    Thus, the main <filename>PN</filename> package
                    does not include the above listed files.
                </para>
            </section>

            <section id='packaging-externally-produced-binaries'>
                <title>Packaging Externally Produced Binaries</title>

                <para>
                    Sometimes, you need to add pre-compiled binaries to an
                    image.
                    For example, suppose that binaries for proprietary code
                    exist, which are created by a particular division of a
                    company.
                    Your part of the company needs to use those binaries as
                    part of an image that you are building using the
                    OpenEmbedded build system.
                    Since you only have the binaries and not the source code,
                    you cannot use a typical recipe that expects to fetch the
                    source specified in
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                    and then compile it.
                </para>

                <para>
                    One method is to package the binaries and then install them
                    as part of the image.
                    Generally, it is not a good idea to package binaries
                    since, among other things, it can hinder the ability to
                    reproduce builds and could lead to compatibility problems
                    with ABI in the future.
                    However, sometimes you have no choice.
                </para>

                <para>
                    The easiest solution is to create a recipe that uses
                    the
                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-bin-package'><filename>bin_package</filename></ulink>
                    class and to be sure that you are using default locations
                    for build artifacts.
                    In most cases, the <filename>bin_package</filename> class
                    handles "skipping" the configure and compile steps as well
                    as sets things up to grab packages from the appropriate
                    area.
                    In particular, this class sets <filename>noexec</filename>
                    on both the
                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-configure'><filename>do_configure</filename></ulink>
                    and
                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-compile'><filename>do_compile</filename></ulink>
                    tasks, sets
                    <filename>FILES_${PN}</filename> to "/" so that it picks
                    up all files, and sets up a
                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
                    task, which effectively copies all files from
                    <filename>${S}</filename> to <filename>${D}</filename>.
                    The <filename>bin_package</filename> class works well when
                    the files extracted into <filename>${S}</filename> are
                    already laid out in the way they should be laid out
                    on the target.
                    For more information on these variables, see the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-FILES'><filename>FILES</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>,
                    and
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-D'><filename>D</filename></ulink>
                    variables in the Yocto Project Reference Manual's variable
                    glossary.
                    <note><title>Notes</title>
                        <itemizedlist>
                            <listitem><para>
                                Using
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
                                is a good idea even for components distributed
                                in binary form, and is often necessary for
                                shared libraries.
                                For a shared library, listing the library
                                dependencies in
                                <filename>DEPENDS</filename> makes sure that
                                the libraries are available in the staging
                                sysroot when other recipes link against the
                                library, which might be necessary for
                                successful linking.
                                </para></listitem>
                            <listitem><para>
                                Using <filename>DEPENDS</filename> also
                                allows runtime dependencies between packages
                                to be added automatically.
                                See the
                                "<ulink url='&YOCTO_DOCS_REF_URL;#automatically-added-runtime-dependencies'>Automatically Added Runtime Dependencies</ulink>"
                                section in the Yocto Project Reference Manual
                                for more information.
                                </para></listitem>
                        </itemizedlist>
                    </note>
                </para>

                <para>
                    If you cannot use the <filename>bin_package</filename>
                    class, you need to be sure you are doing the following:
                    <itemizedlist>
                        <listitem><para>
                            Create a recipe where the
                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-configure'><filename>do_configure</filename></ulink>
                            and
                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-compile'><filename>do_compile</filename></ulink>
                            tasks do nothing:
                            It is usually sufficient to just not define these
                            tasks in the recipe, because the default
                            implementations do nothing unless a Makefile is
                            found in
                            <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink><filename>}</filename>.
                            </para>

                            <para>If
                            <filename>${S}</filename> might contain a Makefile,
                            or if you inherit some class that replaces
                            <filename>do_configure</filename> and
                            <filename>do_compile</filename> with custom
                            versions, then you can use the
                            <filename>[</filename><ulink url='&YOCTO_DOCS_BB_URL;#variable-flags'><filename>noexec</filename></ulink><filename>]</filename>
                            flag to turn the tasks into no-ops, as follows:
                            <literallayout class='monospaced'>
     do_configure[noexec] = "1"
     do_compile[noexec] = "1"
                            </literallayout>
                            Unlike
                            <ulink url='&YOCTO_DOCS_BB_URL;#deleting-a-task'><filename>deleting the tasks</filename></ulink>,
                            using the flag preserves the dependency chain from
                            the
                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-fetch'><filename>do_fetch</filename></ulink>,                     <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-unpack'><filename>do_unpack</filename></ulink>,
                            and
                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-patch'><filename>do_patch</filename></ulink>
                            tasks to the
                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
                            task.
                            </para></listitem>
                        <listitem><para>Make sure your
                            <filename>do_install</filename> task installs the
                            binaries appropriately.
                            </para></listitem>
                        <listitem><para>Ensure that you set up
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-FILES'><filename>FILES</filename></ulink>
                            (usually
                            <filename>FILES_${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink><filename>}</filename>)
                            to point to the files you have installed, which of
                            course depends on where you have installed them
                            and whether those files are in different locations
                            than the defaults.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>
        </section>

        <section id="following-recipe-style-guidelines">
            <title>Following Recipe Style Guidelines</title>

            <para>
                When writing recipes, it is good to conform to existing
                style guidelines.
                The
                <ulink url='http://www.openembedded.org/wiki/Styleguide'>OpenEmbedded Styleguide</ulink>
                wiki page provides rough guidelines for preferred recipe style.
            </para>

            <para>
                It is common for existing recipes to deviate a bit from this
                style.
                However, aiming for at least a consistent style is a good idea.
                Some practices, such as omitting spaces around
                <filename>=</filename> operators in assignments or ordering
                recipe components in an erratic way, are widely seen as poor
                style.
            </para>
        </section>
    </section>

    <section id="platdev-newmachine">
        <title>Adding a New Machine</title>

        <para>
            Adding a new machine to the Yocto Project is a straightforward
            process.
            This section describes how to add machines that are similar
            to those that the Yocto Project already supports.
            <note>
                Although well within the capabilities of the Yocto Project,
                adding a totally new architecture might require
                changes to <filename>gcc/glibc</filename> and to the site
                information, which is beyond the scope of this manual.
            </note>
        </para>

        <para>
            For a complete example that shows how to add a new machine,
            see the
            "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>"
            section in the Yocto Project Board Support Package (BSP) Developer's Guide.
        </para>

        <section id="platdev-newmachine-conffile">
            <title>Adding the Machine Configuration File</title>

            <para>
                To add a new machine, you need to add a new machine
                configuration file to the layer's
                <filename>conf/machine</filename> directory.
                This configuration file provides details about the device
                you are adding.
            </para>

            <para>
                The OpenEmbedded build system uses the root name of the
                machine configuration file to reference the new machine.
                For example, given a machine configuration file named
                <filename>crownbay.conf</filename>, the build system
                recognizes the machine as "crownbay".
            </para>

            <para>
                The most important variables you must set in your machine
                configuration file or include from a lower-level configuration
                file are as follows:
                <itemizedlist>
                    <listitem><para><filename><ulink url='&YOCTO_DOCS_REF_URL;#var-TARGET_ARCH'>TARGET_ARCH</ulink></filename>
                        (e.g. "arm")</para></listitem>
                    <listitem><para><filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PREFERRED_PROVIDER'>PREFERRED_PROVIDER</ulink>_virtual/kernel</filename>
                        </para></listitem>
                    <listitem><para><filename><ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE_FEATURES'>MACHINE_FEATURES</ulink></filename>
                        (e.g. "apm screen wifi")</para></listitem>
                </itemizedlist>
            </para>

            <para>
                You might also need these variables:
                <itemizedlist>
                    <listitem><para><filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SERIAL_CONSOLES'>SERIAL_CONSOLES</ulink></filename>
                        (e.g. "115200;ttyS0 115200;ttyS1")</para></listitem>
                    <listitem><para><filename><ulink url='&YOCTO_DOCS_REF_URL;#var-KERNEL_IMAGETYPE'>KERNEL_IMAGETYPE</ulink></filename>
                        (e.g. "zImage")</para></listitem>
                    <listitem><para><filename><ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FSTYPES'>IMAGE_FSTYPES</ulink></filename>
                        (e.g. "tar.gz jffs2")</para></listitem>
                </itemizedlist>
            </para>

            <para>
                You can find full details on these variables in the reference
                section.
                You can leverage existing machine <filename>.conf</filename>
                files from <filename>meta-yocto-bsp/conf/machine/</filename>.
            </para>
        </section>

        <section id="platdev-newmachine-kernel">
            <title>Adding a Kernel for the Machine</title>

            <para>
                The OpenEmbedded build system needs to be able to build a kernel
                for the machine.
                You need to either create a new kernel recipe for this machine,
                or extend an existing kernel recipe.
                You can find several kernel recipe examples in the
                Source Directory at
                <filename>meta/recipes-kernel/linux</filename>
                that you can use as references.
            </para>

            <para>
                If you are creating a new kernel recipe, normal recipe-writing
                rules apply for setting up a
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'>SRC_URI</ulink></filename>.
                Thus, you need to specify any necessary patches and set
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-S'>S</ulink></filename>
                to point at the source code.
                You need to create a <filename>do_configure</filename> task that
                configures the unpacked kernel with a
                <filename>defconfig</filename> file.
                You can do this by using a <filename>make defconfig</filename>
                command or, more commonly, by copying in a suitable
                <filename>defconfig</filename> file and then running
                <filename>make oldconfig</filename>.
                By making use of <filename>inherit kernel</filename> and
                potentially some of the <filename>linux-*.inc</filename> files,
                most other functionality is centralized and the defaults of the
                class normally work well.
            </para>

            <para>
                If you are extending an existing kernel recipe, it is usually
                a matter of adding a suitable <filename>defconfig</filename>
                file.
                The file needs to be added into a location similar to
                <filename>defconfig</filename> files used for other machines
                in a given kernel recipe.
                A possible way to do this is by listing the file in the
                <filename>SRC_URI</filename> and adding the machine to the
                expression in
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-COMPATIBLE_MACHINE'>COMPATIBLE_MACHINE</ulink></filename>:
                <literallayout class='monospaced'>
     COMPATIBLE_MACHINE = '(qemux86|qemumips)'
                </literallayout>
                For more information on <filename>defconfig</filename> files,
                see the
                "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#changing-the-configuration'>Changing the Configuration</ulink>"
                section in the Yocto Project Linux Kernel Development Manual.
            </para>
        </section>

        <section id="platdev-newmachine-formfactor">
            <title>Adding a Formfactor Configuration File</title>

            <para>
                A formfactor configuration file provides information about the
                target hardware for which the image is being built and information that
                the build system cannot obtain from other sources such as the kernel.
                Some examples of information contained in a formfactor configuration file include
                framebuffer orientation, whether or not the system has a keyboard,
                the positioning of the keyboard in relation to the screen, and
                the screen resolution.
            </para>

            <para>
                The build system uses reasonable defaults in most cases.
                However, if customization is
                necessary, you need to create a <filename>machconfig</filename> file
                in the <filename>meta/recipes-bsp/formfactor/files</filename>
                directory.
                This directory contains directories for specific machines such as
                <filename>qemuarm</filename> and <filename>qemux86</filename>.
                For information about the settings available and the defaults, see the
                <filename>meta/recipes-bsp/formfactor/files/config</filename> file found in the
                same area.
            </para>

            <para>
                Following is an example for "qemuarm" machine:
                <literallayout class='monospaced'>
     HAVE_TOUCHSCREEN=1
     HAVE_KEYBOARD=1

     DISPLAY_CAN_ROTATE=0
     DISPLAY_ORIENTATION=0
     #DISPLAY_WIDTH_PIXELS=640
     #DISPLAY_HEIGHT_PIXELS=480
     #DISPLAY_BPP=16
     DISPLAY_DPI=150
     DISPLAY_SUBPIXEL_ORDER=vrgb
                </literallayout>
            </para>
        </section>
    </section>

    <section id='finding-the-temporary-source-code'>
        <title>Finding Temporary Source Code</title>

        <para>
            You might find it helpful during development to modify the
            temporary source code used by recipes to build packages.
            For example, suppose you are developing a patch and you need to
            experiment a bit to figure out your solution.
            After you have initially built the package, you can iteratively
            tweak the source code, which is located in the
            <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>,
            and then you can force a re-compile and quickly test your altered
            code.
            Once you settle on a solution, you can then preserve your changes
            in the form of patches.
        </para>

        <para>
            During a build, the unpacked temporary source code used by recipes
            to build packages is available in the Build Directory as
            defined by the
            <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>
            variable.
            Below is the default value for the <filename>S</filename> variable
            as defined in the
            <filename>meta/conf/bitbake.conf</filename> configuration file
            in the
            <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>:
            <literallayout class='monospaced'>
     S = "${WORKDIR}/${BP}"
            </literallayout>
            You should be aware that many recipes override the
            <filename>S</filename> variable.
            For example, recipes that fetch their source from Git usually set
            <filename>S</filename> to <filename>${WORKDIR}/git</filename>.
            <note>
                The
                <ulink url='&YOCTO_DOCS_REF_URL;#var-BP'><filename>BP</filename></ulink>
                represents the base recipe name, which consists of the name
                and version:
                <literallayout class='monospaced'>
     BP = "${BPN}-${PV}"
                </literallayout>
            </note>
        </para>

        <para>
            The path to the work directory for the recipe
            (<ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>)
            is defined as follows:
            <literallayout class='monospaced'>
     ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
            </literallayout>
            The actual directory depends on several things:
            <itemizedlist>
                <listitem><para>
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>:
                    The top-level build output directory.
                    </para></listitem>
                <listitem><para>
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-MULTIMACH_TARGET_SYS'><filename>MULTIMACH_TARGET_SYS</filename></ulink>:
                    The target system identifier.
                    </para></listitem>
                <listitem><para>
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink>:
                    The recipe name.
                    </para></listitem>
                <listitem><para>
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTENDPE'><filename>EXTENDPE</filename></ulink>:
                    The epoch - (if
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PE'><filename>PE</filename></ulink>
                    is not specified, which is usually the case for most
                    recipes, then <filename>EXTENDPE</filename> is blank).
                    </para></listitem>
                <listitem><para>
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>:
                    The recipe version.
                    </para></listitem>
                <listitem><para>
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>:
                    The recipe revision.
                    </para></listitem>
            </itemizedlist>
        </para>

        <para>
            As an example, assume a Source Directory top-level folder
            named <filename>poky</filename>, a default Build Directory at
            <filename>poky/build</filename>, and a
            <filename>qemux86-poky-linux</filename> machine target
            system.
            Furthermore, suppose your recipe is named
            <filename>foo_1.3.0.bb</filename>.
            In this case, the work directory the build system uses to
            build the package would be as follows:
            <literallayout class='monospaced'>
     poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
            </literallayout>
        </para>
    </section>

    <section id="using-a-quilt-workflow">
        <title>Using Quilt in Your Workflow</title>

        <para>
            <ulink url='http://savannah.nongnu.org/projects/quilt'>Quilt</ulink>
            is a powerful tool that allows you to capture source code changes
            without having a clean source tree.
            This section outlines the typical workflow you can use to modify
            source code, test changes, and then preserve the changes in the
            form of a patch all using Quilt.
            <note><title>Tip</title>
                With regard to preserving changes to source files, if you
                clean a recipe or have <filename>rm_work</filename> enabled,
                the
                <ulink url='&YOCTO_DOCS_SDK_URL;#using-devtool-in-your-sdk-workflow'><filename>devtool</filename> workflow</ulink>
                as described in the Yocto Project Software Development Kit
                (SDK) Developer's Guide is a safer development flow than the
                flow that uses Quilt.
            </note>
        </para>

        <para>
            Follow these general steps:
            <orderedlist>
                <listitem><para>
                    <emphasis>Find the Source Code:</emphasis>
                    Temporary source code used by the OpenEmbedded build system
                    is kept in the
                    <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
                    See the
                    "<link linkend='finding-the-temporary-source-code'>Finding Temporary Source Code</link>"
                    section to learn how to locate the directory that has the
                    temporary source code for a particular package.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Change Your Working Directory:</emphasis>
                    You need to be in the directory that has the temporary
                    source code.
                    That directory is defined by the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>
                    variable.</para></listitem>
                <listitem><para>
                    <emphasis>Create a New Patch:</emphasis>
                    Before modifying source code, you need to create a new
                    patch.
                    To create a new patch file, use
                    <filename>quilt new</filename> as below:
                    <literallayout class='monospaced'>
     $ quilt new my_changes.patch
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Notify Quilt and Add Files:</emphasis>
                    After creating the patch, you need to notify Quilt about
                    the files you plan to edit.
                    You notify Quilt by adding the files to the patch you
                    just created:
                    <literallayout class='monospaced'>
     $ quilt add file1.c file2.c file3.c
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Edit the Files:</emphasis>
                    Make your changes in the source code to the files you added
                    to the patch.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Test Your Changes:</emphasis>
                    Once you have modified the source code, the easiest way to
                    test your changes is by calling the
                    <filename>do_compile</filename> task as shown in the
                    following example:
                    <literallayout class='monospaced'>
     $ bitbake -c compile -f <replaceable>package</replaceable>
                    </literallayout>
                    The <filename>-f</filename> or <filename>--force</filename>
                    option forces the specified task to execute.
                    If you find problems with your code, you can just keep
                    editing and re-testing iteratively until things work
                    as expected.
                    <note>
                        All the modifications you make to the temporary
                        source code disappear once you run the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-clean'><filename>do_clean</filename></ulink>
                        or
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-cleanall'><filename>do_cleanall</filename></ulink>
                        tasks using BitBake (i.e.
                        <filename>bitbake -c clean <replaceable>package</replaceable></filename>
                        and
                        <filename>bitbake -c cleanall <replaceable>package</replaceable></filename>).
                        Modifications will also disappear if you use the
                        <filename>rm_work</filename> feature as described
                        in the
                        "<ulink url='&YOCTO_DOCS_QS_URL;#qs-building-images'>Building Images</ulink>"
                        section of the Yocto Project Quick Start.
                    </note>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Generate the Patch:</emphasis>
                    Once your changes work as expected, you need to use Quilt
                    to generate the final patch that contains all your
                    modifications.
                    <literallayout class='monospaced'>
     $ quilt refresh
                    </literallayout>
                    At this point, the <filename>my_changes.patch</filename>
                    file has all your edits made to the
                    <filename>file1.c</filename>, <filename>file2.c</filename>,
                    and <filename>file3.c</filename> files.</para>

                    <para>You can find the resulting patch file in the
                    <filename>patches/</filename> subdirectory of the source
                    (<filename>S</filename>) directory.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Copy the Patch File:</emphasis>
                    For simplicity, copy the patch file into a directory
                    named <filename>files</filename>, which you can create
                    in the same directory that holds the recipe
                    (<filename>.bb</filename>) file or the append
                    (<filename>.bbappend</filename>) file.
                    Placing the patch here guarantees that the OpenEmbedded
                    build system will find the patch.
                    Next, add the patch into the
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'>SRC_URI</ulink></filename>
                    of the recipe.
                    Here is an example:
                    <literallayout class='monospaced'>
     SRC_URI += "file://my_changes.patch"
                    </literallayout>
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

    <section id="platdev-appdev-devshell">
        <title>Using a Development Shell</title>

        <para>
            When debugging certain commands or even when just editing packages,
            <filename>devshell</filename> can be a useful tool.
            When you invoke <filename>devshell</filename>, all tasks up to and
            including
            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-patch'><filename>do_patch</filename></ulink>
            are run for the specified target.
            Then, a new terminal is opened and you are placed in
            <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink><filename>}</filename>,
            the source directory.
            In the new terminal, all the OpenEmbedded build-related environment variables are
            still defined so you can use commands such as <filename>configure</filename> and
            <filename>make</filename>.
            The commands execute just as if the OpenEmbedded build system were executing them.
            Consequently, working this way can be helpful when debugging a build or preparing
            software to be used with the OpenEmbedded build system.
        </para>

        <para>
            Following is an example that uses <filename>devshell</filename> on a target named
            <filename>matchbox-desktop</filename>:
            <literallayout class='monospaced'>
     $ bitbake matchbox-desktop -c devshell
            </literallayout>
        </para>

        <para>
            This command spawns a terminal with a shell prompt within the OpenEmbedded build environment.
            The <ulink url='&YOCTO_DOCS_REF_URL;#var-OE_TERMINAL'><filename>OE_TERMINAL</filename></ulink>
            variable controls what type of shell is opened.
        </para>

        <para>
            For spawned terminals, the following occurs:
            <itemizedlist>
                <listitem><para>The <filename>PATH</filename> variable includes the
                    cross-toolchain.</para></listitem>
                <listitem><para>The <filename>pkgconfig</filename> variables find the correct
                    <filename>.pc</filename> files.</para></listitem>
                <listitem><para>The <filename>configure</filename> command finds the
                    Yocto Project site files as well as any other necessary files.</para></listitem>
            </itemizedlist>
        </para>

        <para>
            Within this environment, you can run configure or compile
            commands as if they were being run by
            the OpenEmbedded build system itself.
            As noted earlier, the working directory also automatically changes to the
            Source Directory (<ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>).
        </para>

        <para>
            To manually run a specific task using <filename>devshell</filename>,
            run the corresponding <filename>run.*</filename> script in
            the
            <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}/temp</filename>
            directory (e.g.,
            <filename>run.do_configure.</filename><replaceable>pid</replaceable>).
            If a task's script does not exist, which would be the case if the task was
            skipped by way of the sstate cache, you can create the task by first running
            it outside of the <filename>devshell</filename>:
            <literallayout class='monospaced'>
     $ bitbake -c <replaceable>task</replaceable>
            </literallayout>
            <note><title>Notes</title>
                <itemizedlist>
                    <listitem><para>Execution of a task's <filename>run.*</filename>
                        script and BitBake's execution of a task are identical.
                        In other words, running the script re-runs the task
                        just as it would be run using the
                        <filename>bitbake -c</filename> command.
                        </para></listitem>
                    <listitem><para>Any <filename>run.*</filename> file that does not
                        have a <filename>.pid</filename> extension is a
                        symbolic link (symlink) to the most recent version of that
                        file.
                        </para></listitem>
                </itemizedlist>
            </note>
        </para>

        <para>
            Remember, that the <filename>devshell</filename> is a mechanism that allows
            you to get into the BitBake task execution environment.
            And as such, all commands must be called just as BitBake would call them.
            That means you need to provide the appropriate options for
            cross-compilation and so forth as applicable.
        </para>

        <para>
            When you are finished using <filename>devshell</filename>, exit the shell
            or close the terminal window.
        </para>

        <note><title>Notes</title>
            <itemizedlist>
                <listitem><para>
                    It is worth remembering that when using <filename>devshell</filename>
                    you need to use the full compiler name such as <filename>arm-poky-linux-gnueabi-gcc</filename>
                    instead of just using <filename>gcc</filename>.
                    The same applies to other applications such as <filename>binutils</filename>,
                    <filename>libtool</filename> and so forth.
                    BitBake sets up environment variables such as <filename>CC</filename>
                    to assist applications, such as <filename>make</filename> to find the correct tools.
                    </para></listitem>
                <listitem><para>
                    It is also worth noting that <filename>devshell</filename> still works over
                    X11 forwarding and similar situations.
                    </para></listitem>
            </itemizedlist>
        </note>
    </section>

    <section id="platdev-appdev-devpyshell">
        <title>Using a Development Python Shell</title>

        <para>
            Similar to working within a development shell as described in
            the previous section, you can also spawn and work within an
            interactive Python development shell.
            When debugging certain commands or even when just editing packages,
            <filename>devpyshell</filename> can be a useful tool.
            When you invoke <filename>devpyshell</filename>, all tasks up to and
            including
            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-patch'><filename>do_patch</filename></ulink>
            are run for the specified target.
            Then a new terminal is opened.
            Additionally, key Python objects and code are available in the same
            way they are to BitBake tasks, in particular, the data store 'd'.
            So, commands such as the following are useful when exploring the data
            store and running functions:
            <literallayout class='monospaced'>
     pydevshell> d.getVar("STAGING_DIR", True)
     '/media/build1/poky/build/tmp/sysroots'
     pydevshell> d.getVar("STAGING_DIR", False)
     '${TMPDIR}/sysroots'
     pydevshell> d.setVar("FOO", "bar")
     pydevshell> d.getVar("FOO", True)
     'bar'
     pydevshell> d.delVar("FOO")
     pydevshell> d.getVar("FOO", True)
     pydevshell> bb.build.exec_func("do_unpack", d)
     pydevshell>
            </literallayout>
            The commands execute just as if the OpenEmbedded build system were executing them.
            Consequently, working this way can be helpful when debugging a build or preparing
            software to be used with the OpenEmbedded build system.
        </para>

        <para>
            Following is an example that uses <filename>devpyshell</filename> on a target named
            <filename>matchbox-desktop</filename>:
            <literallayout class='monospaced'>
     $ bitbake matchbox-desktop -c devpyshell
            </literallayout>
        </para>

        <para>
            This command spawns a terminal and places you in an interactive
            Python interpreter within the OpenEmbedded build environment.
            The <ulink url='&YOCTO_DOCS_REF_URL;#var-OE_TERMINAL'><filename>OE_TERMINAL</filename></ulink>
            variable controls what type of shell is opened.
        </para>

        <para>
            When you are finished using <filename>devpyshell</filename>, you
            can exit the shell either by using Ctrl+d or closing the terminal
            window.
        </para>
    </section>

    <section id='platdev-building-targets-with-multiple-configurations'>
        <title>Building Targets with Multiple Configurations</title>

        <para>
            Bitbake also has functionality that allows you to build
            multiple targets at the same time, where each target uses
            a different configuration.
        </para>

        <para>
            In order to accomplish this, you setup each of the configurations
            you need to use in parallel by placing the configuration files in
            your current build directory alongside the usual
            <filename>local.conf</filename> file.
        </para>

        <para>
            Follow these guidelines to create an environment that supports
            multiple configurations:
            <itemizedlist>
                <listitem><para>
                    <emphasis>Create Configuration Files</emphasis>:
                    You need to create a single configuration file for each
                    configuration for which you want to add support.
                    These files would contain lines such as the following:
                    <literallayout class='monospaced'>
     MACHINE = "A"
                    </literallayout>
                    The files would contain any other variables that can
                    be set and built in the same directory.
                    <note>
                        You can change the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>
                        to not conflict.
                    </note></para>

                    <para>
                    Furthermore, the configuration file must be located in the
                    current build directory in a directory named
                    <filename>multiconfig</filename> under the build's
                    <filename>conf</filename> directory where
                    <filename>local.conf</filename> resides.
                    The reason for this restriction is because the
                    <filename>BBPATH</filename> variable is not constructed
                    until the layers are parsed.
                    Consequently, using the configuration file as a
                    pre-configuration file is not possible unless it is
                    located in the current working directory.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Add the BitBake Multi-Config Variable to you Local Configuration File</emphasis>:
                    Use the
                    <filename>BBMULTICONFIG</filename>
                    variable in your <filename>conf/local.conf</filename>
                    configuration file to specify each separate configuration.
                    For example, the following line tells BitBake it should load
                    <filename>conf/multiconfig/configA.conf</filename>,
                    <filename>conf/multiconfig/configB.conf</filename>, and
                    <filename>conf/multiconfig/configC.conf</filename>.
                    <literallayout class='monospaced'>
     BBMULTICONFIG = "configA configB configC"
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Launch BitBake</emphasis>:
                    Use the following BitBake command form to launch the
                    build:
                    <literallayout class='monospaced'>
     $ bitbake [multiconfig:<replaceable>multiconfigname</replaceable>:]<replaceable>target</replaceable> [[[multiconfig:<replaceable>multiconfigname</replaceable>:]<replaceable>target</replaceable>] ... ]
                    </literallayout>
                    Following is an example that supports building a minimal
                    image for configuration A alongside a standard
                    <filename>core-image-sato</filename>, which takes its
                    configuration from <filename>local.conf</filename>:
                    <literallayout class='monospaced'>
     $ bitbake multiconfig:configA:core-image-minimal core-image-sato
                    </literallayout>
                    </para></listitem>
            </itemizedlist>
        </para>

        <para>
            Support for multiple configurations in this current release of
            the Yocto Project (&DISTRO_NAME; &DISTRO;) has some known issues:
            <itemizedlist>
                <listitem><para>
                    No inter-multi-configuration dependencies exist.
                    </para></listitem>
                <listitem><para>
                    Shared State (sstate) optimizations do not exist.
                    Consequently, if the build uses the same object twice
                    in, for example, two different
                    <filename>TMPDIR</filename> directories, the build
                    will either load from an existing sstate cache at the
                    start or build the object twice.
                    </para></listitem>
            </itemizedlist>
        </para>
    </section>

    <section id="platdev-working-with-libraries">
        <title>Working With Libraries</title>

        <para>
            Libraries are an integral part of your system.
            This section describes some common practices you might find
            helpful when working with libraries to build your system:
            <itemizedlist>
                <listitem><para><link linkend='including-static-library-files'>How to include static library files</link>
                    </para></listitem>
                <listitem><para><link linkend='combining-multiple-versions-library-files-into-one-image'>How to use the Multilib feature to combine multiple versions of library files into a single image</link>
                    </para></listitem>
                <listitem><para><link linkend='installing-multiple-versions-of-the-same-library'>How to install multiple versions of the same library in parallel on the same system</link>
                    </para></listitem>
            </itemizedlist>
        </para>

        <section id='including-static-library-files'>
            <title>Including Static Library Files</title>

            <para>
                If you are building a library and the library offers static linking, you can control
                which static library files (<filename>*.a</filename> files) get included in the
                built library.
            </para>

            <para>
                The <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'><filename>PACKAGES</filename></ulink>
                and <ulink url='&YOCTO_DOCS_REF_URL;#var-FILES'><filename>FILES_*</filename></ulink>
                variables in the
                <filename>meta/conf/bitbake.conf</filename> configuration file define how files installed
                by the <filename>do_install</filename> task are packaged.
                By default, the <filename>PACKAGES</filename> variable includes
                <filename>${PN}-staticdev</filename>, which represents all static library files.
                <note>
                    Some previously released versions of the Yocto Project
                    defined the static library files through
                    <filename>${PN}-dev</filename>.
                </note>
                Following is part of the BitBake configuration file, where
                you can see how the static library files are defined:
                <literallayout class='monospaced'>
     PACKAGE_BEFORE_PN ?= ""
     PACKAGES = "${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}"
     PACKAGES_DYNAMIC = "^${PN}-locale-.*"
     FILES = ""

     FILES_${PN} = "${bindir}/* ${sbindir}/* ${libexecdir}/* ${libdir}/lib*${SOLIBS} \
                 ${sysconfdir} ${sharedstatedir} ${localstatedir} \
                 ${base_bindir}/* ${base_sbindir}/* \
                 ${base_libdir}/*${SOLIBS} \
                 ${base_prefix}/lib/udev/rules.d ${prefix}/lib/udev/rules.d \
                 ${datadir}/${BPN} ${libdir}/${BPN}/* \
                 ${datadir}/pixmaps ${datadir}/applications \
                 ${datadir}/idl ${datadir}/omf ${datadir}/sounds \
                 ${libdir}/bonobo/servers"

     FILES_${PN}-bin = "${bindir}/* ${sbindir}/*"

     FILES_${PN}-doc = "${docdir} ${mandir} ${infodir} ${datadir}/gtk-doc \
                 ${datadir}/gnome/help"
     SECTION_${PN}-doc = "doc"

     FILES_SOLIBSDEV ?= "${base_libdir}/lib*${SOLIBSDEV} ${libdir}/lib*${SOLIBSDEV}"
     FILES_${PN}-dev = "${includedir} ${FILES_SOLIBSDEV} ${libdir}/*.la \
                     ${libdir}/*.o ${libdir}/pkgconfig ${datadir}/pkgconfig \
                     ${datadir}/aclocal ${base_libdir}/*.o \
                     ${libdir}/${BPN}/*.la ${base_libdir}/*.la"
     SECTION_${PN}-dev = "devel"
     ALLOW_EMPTY_${PN}-dev = "1"
     RDEPENDS_${PN}-dev = "${PN} (= ${EXTENDPKGV})"

     FILES_${PN}-staticdev = "${libdir}/*.a ${base_libdir}/*.a ${libdir}/${BPN}/*.a"
     SECTION_${PN}-staticdev = "devel"
     RDEPENDS_${PN}-staticdev = "${PN}-dev (= ${EXTENDPKGV})"
                </literallayout>
            </para>
        </section>

        <section id="combining-multiple-versions-library-files-into-one-image">
            <title>Combining Multiple Versions of Library Files into One Image</title>

            <para>
                The build system offers the ability to build libraries with different
                target optimizations or architecture formats and combine these together
                into one system image.
                You can link different binaries in the image
                against the different libraries as needed for specific use cases.
                This feature is called "Multilib."
            </para>

            <para>
                An example would be where you have most of a system compiled in 32-bit
                mode using 32-bit libraries, but you have something large, like a database
                engine, that needs to be a 64-bit application and uses 64-bit libraries.
                Multilib allows you to get the best of both 32-bit and 64-bit libraries.
            </para>

            <para>
                While the Multilib feature is most commonly used for 32 and 64-bit differences,
                the approach the build system uses facilitates different target optimizations.
                You could compile some binaries to use one set of libraries and other binaries
                to use a different set of libraries.
                The libraries could differ in architecture, compiler options, or other
                optimizations.
            </para>

            <para>
                Several examples exist in the
                <filename>meta-skeleton</filename> layer found in the
               <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>:
                <itemizedlist>
                    <listitem><para><filename>conf/multilib-example.conf</filename>
                        configuration file</para></listitem>
                    <listitem><para><filename>conf/multilib-example2.conf</filename>
                        configuration file</para></listitem>
                    <listitem><para><filename>recipes-multilib/images/core-image-multilib-example.bb</filename>
                        recipe</para></listitem>
                </itemizedlist>
            </para>

            <section id='preparing-to-use-multilib'>
                <title>Preparing to Use Multilib</title>

                <para>
                    User-specific requirements drive the Multilib feature.
                    Consequently, there is no one "out-of-the-box" configuration that likely
                    exists to meet your needs.
                </para>

                <para>
                    In order to enable Multilib, you first need to ensure your recipe is
                    extended to support multiple libraries.
                    Many standard recipes are already extended and support multiple libraries.
                    You can check in the <filename>meta/conf/multilib.conf</filename>
                    configuration file in the
                    <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink> to see how this is
                    done using the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-BBCLASSEXTEND'><filename>BBCLASSEXTEND</filename></ulink>
                    variable.
                    Eventually, all recipes will be covered and this list will
                    not be needed.
                </para>

                <para>
                    For the most part, the Multilib class extension works automatically to
                    extend the package name from <filename>${PN}</filename> to
                    <filename>${MLPREFIX}${PN}</filename>, where <filename>MLPREFIX</filename>
                    is the particular multilib (e.g. "lib32-" or "lib64-").
                    Standard variables such as
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'><filename>RDEPENDS</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-RPROVIDES'><filename>RPROVIDES</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-RRECOMMENDS'><filename>RRECOMMENDS</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'><filename>PACKAGES</filename></ulink>, and
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES_DYNAMIC'><filename>PACKAGES_DYNAMIC</filename></ulink>
                    are automatically extended by the system.
                    If you are extending any manual code in the recipe, you can use the
                    <filename>${MLPREFIX}</filename> variable to ensure those names are extended
                    correctly.
                    This automatic extension code resides in <filename>multilib.bbclass</filename>.
                </para>
            </section>

            <section id='using-multilib'>
                <title>Using Multilib</title>

                <para>
                    After you have set up the recipes, you need to define the actual
                    combination of multiple libraries you want to build.
                    You accomplish this through your <filename>local.conf</filename>
                    configuration file in the
                    <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
                    An example configuration would be as follows:
                    <literallayout class='monospaced'>
     MACHINE = "qemux86-64"
     require conf/multilib.conf
     MULTILIBS = "multilib:lib32"
     DEFAULTTUNE_virtclass-multilib-lib32 = "x86"
     IMAGE_INSTALL_append = " lib32-glib-2.0"
                    </literallayout>
                    This example enables an
                    additional library named <filename>lib32</filename> alongside the
                    normal target packages.
                    When combining these "lib32" alternatives, the example uses "x86" for tuning.
                    For information on this particular tuning, see
                    <filename>meta/conf/machine/include/ia32/arch-ia32.inc</filename>.
                </para>

                <para>
                    The example then includes <filename>lib32-glib-2.0</filename>
                    in all the images, which illustrates one method of including a
                    multiple library dependency.
                    You can use a normal image build to include this dependency,
                    for example:
                    <literallayout class='monospaced'>
     $ bitbake core-image-sato
                    </literallayout>
                    You can also build Multilib packages specifically with a command like this:
                    <literallayout class='monospaced'>
     $ bitbake lib32-glib-2.0
                    </literallayout>
                </para>
            </section>

            <section id='additional-implementation-details'>
                <title>Additional Implementation Details</title>

                <para>
                    Generic implementation details as well as details that are
                    specific to package management systems exist.
                    Following are implementation details that exist regardless
                    of the package management system:
                    <itemizedlist>
                        <listitem><para>The typical convention used for the
                            class extension code as used by
                            Multilib assumes that all package names specified
                            in
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'><filename>PACKAGES</filename></ulink>
                            that contain <filename>${PN}</filename> have
                            <filename>${PN}</filename> at the start of the name.
                            When that convention is not followed and
                            <filename>${PN}</filename> appears at
                            the middle or the end of a name, problems occur.
                            </para></listitem>
                        <listitem><para>The
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-TARGET_VENDOR'><filename>TARGET_VENDOR</filename></ulink>
                            value under Multilib will be extended to
                            "-<replaceable>vendor</replaceable>ml<replaceable>multilib</replaceable>"
                            (e.g. "-pokymllib32" for a "lib32" Multilib with
                            Poky).
                            The reason for this slightly unwieldy contraction
                            is that any "-" characters in the vendor
                            string presently break Autoconf's
                            <filename>config.sub</filename>, and
                            other separators are problematic for different
                            reasons.
                            </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    For the RPM Package Management System, the following implementation details
                    exist:
                    <itemizedlist>
                        <listitem><para>A unique architecture is defined for the Multilib packages,
                            along with creating a unique deploy folder under
                            <filename>tmp/deploy/rpm</filename> in the
                            <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
                            For example, consider <filename>lib32</filename> in a
                            <filename>qemux86-64</filename> image.
                            The possible architectures in the system are "all", "qemux86_64",
                            "lib32_qemux86_64", and "lib32_x86".</para></listitem>
                        <listitem><para>The <filename>${MLPREFIX}</filename> variable is stripped from
                            <filename>${PN}</filename> during RPM packaging.
                            The naming for a normal RPM package and a Multilib RPM package in a
                            <filename>qemux86-64</filename> system resolves to something similar to
                            <filename>bash-4.1-r2.x86_64.rpm</filename> and
                            <filename>bash-4.1.r2.lib32_x86.rpm</filename>, respectively.
                            </para></listitem>
                        <listitem><para>When installing a Multilib image, the RPM backend first
                            installs the base image and then installs the Multilib libraries.
                            </para></listitem>
                        <listitem><para>The build system relies on RPM to resolve the identical files in the
                            two (or more) Multilib packages.</para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    For the IPK Package Management System, the following implementation details exist:
                    <itemizedlist>
                        <listitem><para>The <filename>${MLPREFIX}</filename> is not stripped from
                            <filename>${PN}</filename> during IPK packaging.
                            The naming for a normal RPM package and a Multilib IPK package in a
                            <filename>qemux86-64</filename> system resolves to something like
                            <filename>bash_4.1-r2.x86_64.ipk</filename> and
                            <filename>lib32-bash_4.1-rw_x86.ipk</filename>, respectively.
                            </para></listitem>
                        <listitem><para>The IPK deploy folder is not modified with
                            <filename>${MLPREFIX}</filename> because packages with and without
                            the Multilib feature can exist in the same folder due to the
                            <filename>${PN}</filename> differences.</para></listitem>
                        <listitem><para>IPK defines a sanity check for Multilib installation
                            using certain rules for file comparison, overridden, etc.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>
        </section>

        <section id='installing-multiple-versions-of-the-same-library'>
            <title>Installing Multiple Versions of the Same Library</title>

            <para>
                Situations can exist where you need to install and use
                multiple versions of the same library on the same system
                at the same time.
                These situations almost always exist when a library API
                changes and you have multiple pieces of software that
                depend on the separate versions of the library.
                To accommodate these situations, you can install multiple
                versions of the same library in parallel on the same system.
            </para>

            <para>
                The process is straightforward as long as the libraries use
                proper versioning.
                With properly versioned libraries, all you need to do to
                individually specify the libraries is create separate,
                appropriately named recipes where the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink> part of the
                name includes a portion that differentiates each library version
                (e.g.the major part of the version number).
                Thus, instead of having a single recipe that loads one version
                of a library (e.g. <filename>clutter</filename>), you provide
                multiple recipes that result in different versions
                of the libraries you want.
                As an example, the following two recipes would allow the
                two separate versions of the <filename>clutter</filename>
                library to co-exist on the same system:
                <literallayout class='monospaced'>
     clutter-1.6_1.6.20.bb
     clutter-1.8_1.8.4.bb
                </literallayout>
                Additionally, if you have other recipes that depend on a given
                library, you need to use the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
                variable to create the dependency.
                Continuing with the same example, if you want to have a recipe
                depend on the 1.8 version of the <filename>clutter</filename>
                library, use the following in your recipe:
                <literallayout class='monospaced'>
     DEPENDS = "clutter-1.8"
                </literallayout>
            </para>
        </section>
    </section>

    <section id='enabling-gobject-introspection-support'>
        <title>Enabling GObject Introspection Support</title>

        <para>
            <ulink url='https://wiki.gnome.org/Projects/GObjectIntrospection'>GObject introspection</ulink>
            is the standard mechanism for accessing GObject-based software
            from runtime environments.
            GObject is a feature of the GLib library that provides an object
            framework for the GNOME desktop and related software.
            GObject Introspection adds information to GObject that allows
            objects created within it to be represented across different
            programming languages.
            If you want to construct GStreamer pipelines using Python, or
            control UPnP infrastructure using Javascript and GUPnP,
            GObject introspection is the only way to do it.
        </para>

        <para>
            This section describes the Yocto Project support for generating
            and packaging GObject introspection data.
            GObject introspection data is a description of the
            API provided by libraries built on top of GLib framework,
            and, in particular, that framework's GObject mechanism.
            GObject Introspection Repository (GIR) files go to
            <filename>-dev</filename> packages,
            <filename>typelib</filename> files go to main packages as they
            are packaged together with libraries that are introspected.
        </para>

        <para>
            The data is generated when building such a library, by linking
            the library with a small executable binary that asks the library
            to describe itself, and then executing the binary and
            processing its output.
        </para>

        <para>
            Generating this data in a cross-compilation environment
            is difficult because the library is produced for the target
            architecture, but its code needs to be executed on the build host.
            This problem is solved with the OpenEmbedded build system by
            running the code through QEMU, which allows precisely that.
            Unfortunately, QEMU does not always work perfectly as mentioned
            in the xxx section.
        </para>

        <section id='enabling-the-generation-of-introspection-data'>
            <title>Enabling the Generation of Introspection Data</title>

            <para>
                Enabling the generation of introspection data (GIR files)
                in your library package involves the following:
                <orderedlist>
                    <listitem><para>
                        Inherit the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-gobject-introspection'><filename>gobject-introspection</filename></ulink>
                        class.
                        </para></listitem>
                    <listitem><para>
                        Make sure introspection is not disabled anywhere in
                        the recipe or from anything the recipe includes.
                        Also, make sure that "gobject-introspection-data" is
                        not in
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES_BACKFILL_CONSIDERED'><filename>DISTRO_FEATURES_BACKFILL_CONSIDERED</filename></ulink>
                        and that "qemu-usermode" is not in
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE_FEATURES_BACKFILL_CONSIDERED'><filename>MACHINE_FEATURES_BACKFILL_CONSIDERED</filename></ulink>.
                        If either of these conditions exist, nothing will
                        happen.
                        </para></listitem>
                    <listitem><para>
                        Try to build the recipe.
                        If you encounter build errors that look like
                        something is unable to find
                        <filename>.so</filename> libraries, check where these
                        libraries are located in the source tree and add
                        the following to the recipe:
                        <literallayout class='monospaced'>
     GIR_EXTRA_LIBS_PATH = "${B}/<replaceable>something</replaceable>/.libs"
                        </literallayout>
                        <note>
                            See recipes in the <filename>oe-core</filename>
                            repository that use that
                            <filename>GIR_EXTRA_LIBS_PATH</filename> variable
                            as an example.
                        </note>
                        </para></listitem>
                    <listitem><para>
                        Look for any other errors, which probably mean that
                        introspection support in a package is not entirely
                        standard, and thus breaks down in a cross-compilation
                        environment.
                        For such cases, custom-made fixes are needed.
                        A good place to ask and receive help in these cases
                        is the
                        <ulink url='&YOCTO_DOCS_REF_URL;#resources-mailinglist'>Yocto Project mailing lists</ulink>.
                        </para></listitem>
                </orderedlist>
                <note>
                    Using a library that no longer builds against the latest
                    Yocto Project release and prints introspection related
                    errors is a good candidate for the previous procedure.
                </note>
            </para>
        </section>

        <section id='disabling-the-generation-of-introspection-data'>
            <title>Disabling the Generation of Introspection Data</title>

            <para>
                You might find that you do not want to generate
                introspection data.
                Or, perhaps QEMU does not work on your build host and
                target architecture combination.
                If so, you can use either of the following methods to
                disable GIR file generations:
                <itemizedlist>
                    <listitem><para>
                        Add the following to your distro configuration:
                        <literallayout class='monospaced'>
     DISTRO_FEATURES_BACKFILL_CONSIDERED = "gobject-introspection-data"
                        </literallayout>
                        Adding this statement disables generating
                        introspection data using QEMU but will still enable
                        building introspection tools and libraries
                        (i.e. building them does not require the use of QEMU).
                        </para></listitem>
                    <listitem><para>
                        Add the following to your machine configuration:
                        <literallayout class='monospaced'>
     MACHINE_FEATURES_BACKFILL_CONSIDERED = "qemu-usermode"
                        </literallayout>
                        Adding this statement disables the use of QEMU
                        when building packages for your machine.
                        Currently, this feature is used only by introspection
                        recipes and has the same effect as the previously
                        described option.
                        <note>
                            Future releases of the Yocto Project might have
                            other features affected by this option.
                        </note>
                        </para></listitem>
                </itemizedlist>
                If you disable introspection data, you can still
                obtain it through other means such as copying the data
                from a suitable sysroot, or by generating it on the
                target hardware.
                The OpenEmbedded build system does not currently
                provide specific support for these techniques.
            </para>
        </section>

        <section id='testing-that-introspection-works-in-an-image'>
            <title>Testing that Introspection Works in an Image</title>

            <para>
                Use the following procedure to test if generating
                introspection data is working in an image:
                <orderedlist>
                    <listitem><para>
                        Make sure that "gobject-introspection-data" is not in
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES_BACKFILL_CONSIDERED'><filename>DISTRO_FEATURES_BACKFILL_CONSIDERED</filename></ulink>
                        and that "qemu-usermode" is not in
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE_FEATURES_BACKFILL_CONSIDERED'><filename>MACHINE_FEATURES_BACKFILL_CONSIDERED</filename></ulink>.
                        </para></listitem>
                    <listitem><para>
                        Build <filename>core-image-sato</filename>.
                        </para></listitem>
                    <listitem><para>
                        Launch a Terminal and then start Python in the
                        terminal.
                        </para></listitem>
                    <listitem><para>
                        Enter the following in the terminal:
                        <literallayout class='monospaced'>
     >>> from gi.repository import GLib
     >>> GLib.get_host_name()
                        </literallayout>
                        </para></listitem>
                    <listitem><para>
                        For something a little more advanced, enter the
                        following:
                        <literallayout class='monospaced'>
     http://python-gtk-3-tutorial.readthedocs.org/en/latest/introduction.html
                        </literallayout>
                        </para></listitem>
                </orderedlist>
            </para>
        </section>

        <section id='known-issues'>
            <title>Known Issues</title>

            <para>
                The following know issues exist for
                GObject Introspection Support:
                <itemizedlist>
                    <listitem><para>
                        <filename>qemu-ppc64</filename> immediately crashes.
                        Consequently, you cannot build introspection data on
                        that architecture.
                        </para></listitem>
                    <listitem><para>
                        x32 is not supported by QEMU.
                        Consequently, introspection data is disabled.
                        </para></listitem>
                    <listitem><para>
                        musl causes transient GLib binaries to crash on
                        assertion failures.
                        Consequently, generating introspection data is
                        disabled.
                        </para></listitem>
                    <listitem><para>
                        Because QEMU is not able to run the binaries correctly,
                        introspection is disabled for some specific packages
                        under specific architectures (e.g.
                        <filename>gcr</filename>,
                        <filename>libsecret</filename>, and
                        <filename>webkit</filename>).
                        </para></listitem>
                    <listitem><para>
                        QEMU usermode might not work properly when running
                        64-bit binaries under 32-bit host machines.
                        In particular, "qemumips64" is known to not work under
                        i686.
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>
    </section>

    <section id='dev-optionally-using-an-external-toolchain'>
        <title>Optionally Using an External Toolchain</title>

        <para>
            You might want to use an external toolchain as part of your
            development.
            If this is the case, the fundamental steps you need to accomplish
            are as follows:
            <itemizedlist>
                <listitem><para>
                    Understand where the installed toolchain resides.
                    For cases where you need to build the external toolchain,
                    you would need to take separate steps to build and install
                    the toolchain.
                    </para></listitem>
                <listitem><para>
                    Make sure you add the layer that contains the toolchain to
                    your <filename>bblayers.conf</filename> file through the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-BBLAYERS'><filename>BBLAYERS</filename></ulink>
                    variable.
                    </para></listitem>
                <listitem><para>
                    Set the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTERNAL_TOOLCHAIN'><filename>EXTERNAL_TOOLCHAIN</filename></ulink>
                    variable in your <filename>local.conf</filename> file
                    to the location in which you installed the toolchain.
                    </para></listitem>
            </itemizedlist>
            A good example of an external toolchain used with the Yocto Project
            is <trademark class='registered'>Mentor Graphics</trademark>
            Sourcery G++ Toolchain.
            You can see information on how to use that particular layer in the
            <filename>README</filename> file at
            <ulink url='http://github.com/MentorEmbedded/meta-sourcery/'></ulink>.
            You can find further information by reading about the
            <ulink url='&YOCTO_DOCS_REF_URL;#var-TCMODE'><filename>TCMODE</filename></ulink>
            variable in the Yocto Project Reference Manual's variable glossary.
        </para>
    </section>

    <section id='creating-partitioned-images'>
        <title>Creating Partitioned Images</title>

        <para>
            Creating an image for a particular hardware target using the
            OpenEmbedded build system does not necessarily mean you can boot
            that image as is on your device.
            Physical devices accept and boot images in various ways depending
            on the specifics of the device.
            Usually, information about the hardware can tell you what image
            format the device requires.
            Should your device require multiple partitions on an SD card, flash,
            or an HDD, you can use the OpenEmbedded Image Creator,
	        Wic, to create the properly partitioned image.
        </para>

        <para>
            You can generate partitioned images
            (<replaceable>image</replaceable><filename>.wic</filename>)
            two ways: using the OpenEmbedded build system and by running
            the OpenEmbedded Image Creator Wic directly.
            The former way is preferable as it is easier to use and understand.
        </para>

        <section id='creating-wic-images-oe'>
            <title>Creating Partitioned Images</title>

            <para>
                The OpenEmbedded build system can generate
                partitioned images the same way as it generates
                any other image type.
                To generate a partitioned image, you need to modify
                two variables.
                <itemizedlist>
                    <listitem><para>
                        Include "wic" as part of the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></ulink>
                        variable.
                        </para></listitem>
                    <listitem><para>
                        Include the name of the
                        <link linkend='openembedded-kickstart-wks-reference'>wic kickstart file</link>
                        as part of the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-WKS_FILE'><filename>WKS_FILE</filename></ulink>
                        variable
                        </para></listitem>
                </itemizedlist>
                Further steps to generate a partitioned image
                are the same as for any other image type.
                For information on image types, see the
                "<ulink url='ref-images'>Images</ulink>"
                section in the Yocto Project Reference Manual.
            </para>
        </section>

        <section id='create-wic-images-wic'>
            <title>Using OpenEmbedded Image Creator Wic to Generate Partitioned Images</title>

            <para>
                The <filename>wic</filename> command generates partitioned
                images from existing OpenEmbedded build artifacts.
                Image generation is driven by partitioning commands
                contained in an Openembedded kickstart file
                (<filename>.wks</filename>) specified either directly on
                the command line or as one of a selection of canned
                <filename>.wks</filename> files as shown with the
                <filename>wic list images</filename> command in the
                "<link linkend='using-a-provided-kickstart-file'>Using an Existing Kickstart File</link>"
                section.
                When you apply the command to a given set of build
                artifacts, the result is an image or set of images that
                can be directly written onto media and used on a particular
                system.
            </para>

            <para>
                The <filename>wic</filename> command and the infrastructure
                it is based on is by definition incomplete.
                The purpose of the command is to allow the generation of
                customized images, and as such, was designed to be
                completely extensible through a plug-in interface.
                See the
                "<link linkend='openembedded-kickstart-plugins'>Plug-ins</link>"
                section for information on these plug-ins.
            </para>

            <para>
                This section provides some background information on Wic,
                describes what you need to have in
                place to run the tool, provides instruction on how to use
                the <filename>wic</filename> utility,
                and provides several examples.
            </para>

            <section id='wic-background'>
                <title>Background</title>

                <para>
                    This section provides some background on the
                    <filename>wic</filename> utility.
                    While none of this information is required to use
                    Wic, you might find it interesting.
                    <itemizedlist>
                        <listitem><para>
                            The name "Wic" is derived from OpenEmbedded
                            Image Creator (oeic).
                            The "oe" diphthong in "oeic" was promoted to the
                            letter "w", because "oeic" is both difficult to
                            remember and to pronounce.
                            </para></listitem>
                        <listitem><para>
                            Wic is loosely based on the
                            Meego Image Creator (<filename>mic</filename>)
                            framework.
                            The Wic implementation has been
                            heavily modified to make direct use of OpenEmbedded
                            build artifacts instead of package installation and
                            configuration, which are already incorporated within
                            the OpenEmbedded artifacts.
                            </para></listitem>
                        <listitem><para>
                            Wic is a completely independent
                            standalone utility that initially provides
                            easier-to-use and more flexible replacements for an
                            existing functionality in OE Core's
                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-image-live'><filename>image-live</filename></ulink>
                            class and <filename>mkefidisk.sh</filename> script.
                            The difference between
                            Wic and those examples is
                            that with Wic the
                            functionality of those scripts is implemented
                            by a general-purpose partitioning language, which is
                            based on Redhat kickstart syntax.</para></listitem>
                    </itemizedlist>
                </para>
            </section>

            <section id='wic-requirements'>
                <title>Requirements</title>

                <para>
                    In order to use the <filename>wic</filename> utility
                    with the OpenEmbedded Build system, your system needs
                    to meet the following requirements:
                    <itemizedlist>
                        <listitem><para>The Linux distribution on your
                            development host must support the Yocto Project.
                            See the
                            "<ulink url='&YOCTO_DOCS_REF_URL;#detailed-supported-distros'>Supported Linux Distributions</ulink>"
                            section in the Yocto Project Reference Manual for
                            the list of distributions that support the
                            Yocto Project.
                            </para></listitem>
                        <listitem><para>
                            The standard system utilities, such as
                            <filename>cp</filename>, must be installed on your
                            development host system.
                            </para></listitem>
                        <listitem><para>
                            You need to have the build artifacts already
                            available, which typically means that you must
                            have already created an image using the
                            Openembedded build system (e.g.
                            <filename>core-image-minimal</filename>).
                            While it might seem redundant to generate an image
                            in order to create an image using
                            Wic, the current version of
                            Wic requires the artifacts
                            in the form generated by the build system.
                            </para></listitem>
                        <listitem><para>
                            You must build several native tools, which are tools
                            built to run on the build system:
                            <literallayout class='monospaced'>
     $ bitbake parted-native dosfstools-native mtools-native
                            </literallayout>
                            </para></listitem>
                        <listitem><para>
                            You must have sourced one of the build environment
                            setup scripts (i.e.
                            <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink>
                            or
                            <ulink url='&YOCTO_DOCS_REF_URL;#structure-memres-core-script'><filename>oe-init-build-env-memres</filename></ulink>)
                            found in the
                            <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>

            <section id='wic-getting-help'>
                <title>Getting Help</title>

                <para>
                    You can get general help for the <filename>wic</filename>
                    command by entering the <filename>wic</filename> command
                    by itself or by entering the command with a help argument
                    as follows:
                    <literallayout class='monospaced'>
     $ wic -h
     $ wic --help
                    </literallayout>
                </para>

                <para>
                    Currently, Wic supports two commands:
                    <filename>create</filename> and <filename>list</filename>.
                    You can get help for these commands as follows:
                    <literallayout class='monospaced'>
     $ wic help <replaceable>command</replaceable>
                    with <replaceable>command</replaceable> being either
                    <filename>create</filename> or <filename>list</filename>.
                    </literallayout>
                </para>

                <para>
                    You can also get detailed help on a number of topics
                    from the help system.
                    The output of <filename>wic --help</filename>
                    displays a list of available help
                    topics under a "Help topics" heading.
                    You can have the help system display the help text for
                    a given topic by prefacing the topic with
                    <filename>wic help</filename>:
                    <literallayout class='monospaced'>
     $ wic help <replaceable>help_topic</replaceable>
                    </literallayout>
                </para>

                <para>
                    You can find out more about the images
                    Wic creates using the existing
                    kickstart files with the following form of the command:
                    <literallayout class='monospaced'>
     $ wic list <replaceable>image</replaceable> help
                    </literallayout>
                    with <filename><replaceable>image</replaceable></filename>
                    being either <filename>directdisk</filename> or
                    <filename>mkefidisk</filename>.
                </para>
            </section>

            <section id='operational-modes'>
                <title>Operational Modes</title>

                <para>
                    You can use Wic in two different
                    modes, depending on how much control you need for
                    specifying the Openembedded build artifacts that are
                    used for creating the image: Raw and Cooked:
                    <itemizedlist>
                        <listitem><para>
                            <emphasis>Raw Mode:</emphasis>
                            You explicitly specify build artifacts through
                            command-line arguments.
                            </para></listitem>
                        <listitem><para>
                            <emphasis>Cooked Mode:</emphasis>
                            The current
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
                            setting and image name are used to automatically
                            locate and provide the build artifacts.
                            </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    Regardless of the mode you use, you need to have the build
                    artifacts ready and available.
                    Additionally, the environment must be set up using the
                    <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink>
                    or
                    <ulink url='&YOCTO_DOCS_REF_URL;#structure-memres-core-script'><filename>oe-init-build-env-memres</filename></ulink>
                    script found in the
                    <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
                </para>

                <section id='raw-mode'>
                    <title>Raw Mode</title>

                    <para>
                        The general form of the
                        <filename>wic</filename> command in raw mode is:
                        <literallayout class='monospaced'>
     $ wic create <replaceable>image_name</replaceable>.wks [<replaceable>options</replaceable>] [...]

       Where:

          <replaceable>image_name</replaceable>.wks
             An OpenEmbedded kickstart file.  You can provide
             your own custom file or use a file from a set of
             existing files as described by further options.

          -o <replaceable>OUTDIR</replaceable>, --outdir=<replaceable>OUTDIR</replaceable>
             The name of a directory in which to create image.

          -i <replaceable>PROPERTIES_FILE</replaceable>, --infile=<replaceable>PROPERTIES_FILE</replaceable>
             The name of a file containing the values for image
             properties as a JSON file.

          -e <replaceable>IMAGE_NAME</replaceable>, --image-name=<replaceable>IMAGE_NAME</replaceable>
             The name of the image from which to use the artifacts
             (e.g. <filename>core-image-sato</filename>).

          -r <replaceable>ROOTFS_DIR</replaceable>, --rootfs-dir=<replaceable>ROOTFS_DIR</replaceable>
             The path to the <filename>/rootfs</filename> directory to use as the
             <filename>.wks</filename> rootfs source.

          -b <replaceable>BOOTIMG_DIR</replaceable>, --bootimg-dir=<replaceable>BOOTIMG_DIR</replaceable>
             The path to the directory containing the boot artifacts
             (e.g. <filename>/EFI</filename> or <filename>/syslinux</filename>) to use as the <filename>.wks</filename> bootimg
             source.

          -k <replaceable>KERNEL_DIR</replaceable>, --kernel-dir=<replaceable>KERNEL_DIR</replaceable>
             The path to the directory containing the kernel to use
             in the <filename>.wks</filename> boot image.

          -n <replaceable>NATIVE_SYSROOT</replaceable>, --native-sysroot=<replaceable>NATIVE_SYSROOT</replaceable>
             The path to the native sysroot containing the tools to use
             to build the image.

          -s, --skip-build-check
              Skips the build check.

          -D, --debug
              Output debug information.
                        </literallayout>
                        <note>
                            You do not need root privileges to run
                            Wic.
                            In fact, you should not run as root when using the
                            utility.
                        </note>
                    </para>
                </section>

                <section id='cooked-mode'>
                    <title>Cooked Mode</title>

                    <para>
                        The general form of the <filename>wic</filename> command
                        using Cooked Mode is:
                        <literallayout class='monospaced'>
     $ wic create <replaceable>kickstart_file</replaceable> -e <replaceable>image_name</replaceable>

       Where:

           <replaceable>kickstart_file</replaceable>
               An OpenEmbedded kickstart file. You can provide your own
               custom file or a supplied file.

           <replaceable>image_name</replaceable>
               Specifies the image built using the OpenEmbedded build
               system.
                        </literallayout>
                        This form is the simplest and most user-friendly, as it
                        does not require specifying all individual parameters.
                        All you need to provide is your own
                        <filename>.wks</filename> file or one provided with the
                        release.
                    </para>
                </section>
            </section>

            <section id='using-a-provided-kickstart-file'>
                <title>Using an Existing Kickstart File</title>

                <para>
                    If you do not want to create your own
                    <filename>.wks</filename> file, you can use an existing
                    file provided by the Wic installation.
                    Use the following command to list the available files:
                    <literallayout class='monospaced'>
     $ wic list images
     directdisk Create a 'pcbios' direct disk image
     mkefidisk Create an EFI disk image
                    </literallayout>
                    When you use an existing file, you do not have to use the
                    <filename>.wks</filename> extension.
                    Here is an example in Raw Mode that uses the
                    <filename>directdisk</filename> file:
                    <literallayout class='monospaced'>
     $ wic create directdisk -r <replaceable>rootfs_dir</replaceable> -b <replaceable>bootimg_dir</replaceable> \
           -k <replaceable>kernel_dir</replaceable> -n <replaceable>native_sysroot</replaceable>
                    </literallayout>
                </para>

                <para>
                    Here are the actual partition language commands
                    used in the <filename>mkefidisk.wks</filename> file to
                    generate an image:
                    <literallayout class='monospaced'>
     # short-description: Create an EFI disk image
     # long-description: Creates a partitioned EFI disk image that the user
     # can directly dd to boot media.

     part /boot --source bootimg-efi --ondisk sda --label msdos --active --align 1024

     part / --source rootfs --ondisk sda --fstype=ext3 --label platform --align 1024

     part swap --ondisk sda --size 44 --label swap1 --fstype=swap

     bootloader  --timeout=10  --append="rootwait rootfstype=ext3 console=ttyPCH0,115200 console=tty0 vmalloc=256MB snd-hda-intel.enable_msi=0"
                    </literallayout>
                </para>
            </section>

            <section id='wic-usage-examples'>
                <title>Examples</title>

                <para>
                    This section provides several examples that show how to use
                    the <filename>wic</filename> utility.
                    All the examples assume the list of requirements in the
                    "<link linkend='wic-requirements'>Requirements</link>"
                    section have been met.
                    The examples assume the previously generated image is
                    <filename>core-image-minimal</filename>.
                </para>

                <section id='generate-an-image-using-a-provided-kickstart-file'>
                    <title>Generate an Image using an Existing Kickstart File</title>

                    <para>
                        This example runs in Cooked Mode and uses the
                        <filename>mkefidisk</filename> kickstart file:
                        <literallayout class='monospaced'>
     $ wic create mkefidisk -e core-image-minimal
     Checking basic build environment...
     Done.

     Creating image(s)...

     Info: The new image(s) can be found here:
      <replaceable>current_directory</replaceable>/build/mkefidisk-201310230946-sda.direct

     The following build artifacts were used to create the image(s):
      ROOTFS_DIR: /home/trz/yocto/yocto-image/build/tmp/work/minnow-poky-linux/core-image-minimal/1.0-r0/rootfs
      BOOTIMG_DIR: /home/trz/yocto/yocto-image/build/tmp/work/minnow-poky-linux/core-image-minimal/1.0-r0/core-image-minimal-1.0/hddimg
      KERNEL_DIR: /home/trz/yocto/yocto-image/build/tmp/sysroots/minnow/usr/src/kernel
      NATIVE_SYSROOT: /home/trz/yocto/yocto-image/build/tmp/sysroots/x86_64-linux

     The image(s) were created using OE kickstart file:
      /home/trz/yocto/yocto-image/scripts/lib/image/canned-wks/mkefidisk.wks
                        </literallayout>
                        The previous example shows the easiest way to create
                        an image by running in Cooked Mode and using the
                        <filename>-e</filename> option with an existing
                        kickstart file.
                        All that is necessary is to specify the image used to
                        generate the artifacts.
                        Your <filename>local.conf</filename> needs to have the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
                        variable set to the machine you are using, which is
                        "minnow" in this example.
                    </para>

                    <para>
                        The output specifies the exact image created as well as
                        where it was created, which is in the current
                        directory by default.
                        The output also names the artifacts used and the exact
                        <filename>.wks</filename> script that was used to
                        generate the image.
                        <note>
                            You should always verify the details provided in the
                            output to make sure that the image was indeed
                            created exactly as expected.
                        </note>
                    </para>

                    <para>
                        Continuing with the example, you can now write the
                        image to a USB stick, or whatever media for which you
                        built your image, and boot the resulting media.
                        You can write the image by using
                        <filename>bmaptool</filename> or
                        <filename>dd</filename>:
                        <literallayout class='monospaced'>
     $ oe-run-native bmaptool copy build/mkefidisk-201310230946-sda.direct /dev/sd<replaceable>X</replaceable>
                        </literallayout>
                        or
                        <literallayout class='monospaced'>
     $ sudo dd if=build/mkefidisk-201310230946-sda.direct of=/dev/sd<replaceable>X</replaceable>
                        </literallayout>
                        <note>
                            For more information on how to use the
                            <filename>bmaptool</filename> to flash a device
                            with an image, see the
                            "<link linkend='flashing-images-using-bmaptool'>Flashing Images Using <filename>bmaptool</filename></link>"
                            section.
                        </note>
                    </para>
                </section>

                <section id='using-a-modified-kickstart-file'>
                    <title>Using a Modified Kickstart File</title>

                    <para>
                        Because partitioned image creation is
                        driven by the kickstart file, it is easy to affect
                        image creation by changing the parameters in the file.
                        This next example demonstrates that through modification
                        of the <filename>directdisk</filename> kickstart file.
                    </para>

                    <para>
                        As mentioned earlier, you can use the command
                        <filename>wic list images</filename> to show the list
                        of existing kickstart files.
                        The directory in which these files reside is
                        <filename>scripts/lib/image/canned-wks/</filename>
                        located in the
                        <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
                        Because the available files reside in this directory,
                        you can create and add your own custom files to the
                        directory.
                        Subsequent use of the
                        <filename>wic list images</filename> command would then
                        include your kickstart files.
                    </para>

                    <para>
                        In this example, the existing
                        <filename>directdisk</filename> file already does most
                        of what is needed.
                        However, for the hardware in this example, the image
                        will need to boot from <filename>sdb</filename> instead
                        of <filename>sda</filename>, which is what the
                        <filename>directdisk</filename> kickstart file uses.
                    </para>

                    <para>
                        The example begins by making a copy of the
                        <filename>directdisk.wks</filename> file in the
                        <filename>scripts/lib/image/canned-wks</filename>
                        directory and then by changing the lines that specify
                        the target disk from which to boot.
                        <literallayout class='monospaced'>
     $ cp /home/trz/yocto/yocto-image/scripts/lib/image/canned-wks/directdisk.wks \
          /home/trz/yocto/yocto-image/scripts/lib/image/canned-wks/directdisksdb.wks
                        </literallayout>
                        Next, the example modifies the
                        <filename>directdisksdb.wks</filename> file and changes
                        all instances of "<filename>--ondisk sda</filename>"
                        to "<filename>--ondisk sdb</filename>".
                        The example changes the following two lines and leaves
                        the remaining lines untouched:
                        <literallayout class='monospaced'>
     part /boot --source bootimg-pcbios --ondisk sdb --label boot --active --align 1024
     part / --source rootfs --ondisk sdb --fstype=ext3 --label platform --align 1024
                        </literallayout>
                        Once the lines are changed, the example generates the
                        <filename>directdisksdb</filename> image.
                        The command points the process at the
                        <filename>core-image-minimal</filename> artifacts for
                        the Next Unit of Computing (nuc)
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
                        the <filename>local.conf</filename>.
                        <literallayout class='monospaced'>
     $ wic create directdisksdb -e core-image-minimal
     Checking basic build environment...
     Done.

     Creating image(s)...

     Info: The new image(s) can be found here:
      <replaceable>current_directory</replaceable>/build/directdisksdb-201310231131-sdb.direct

     The following build artifacts were used to create the image(s):

      ROOTFS_DIR: /home/trz/yocto/yocto-image/build/tmp/work/nuc-poky-linux/core-image-minimal/1.0-r0/rootfs
      BOOTIMG_DIR: /home/trz/yocto/yocto-image/build/tmp/sysroots/nuc/usr/share
      KERNEL_DIR: /home/trz/yocto/yocto-image/build/tmp/sysroots/nuc/usr/src/kernel
      NATIVE_SYSROOT: /home/trz/yocto/yocto-image/build/tmp/sysroots/x86_64-linux

     The image(s) were created using OE kickstart file:
      /home/trz/yocto/yocto-image/scripts/lib/image/canned-wks/directdisksdb.wks
                        </literallayout>
                        Continuing with the example, you can now directly
                        <filename>dd</filename> the image to a USB stick, or
                        whatever media for which you built your image,
                        and boot the resulting media:
                        <literallayout class='monospaced'>
     $ sudo dd if=build/directdisksdb-201310231131-sdb.direct of=/dev/sdb
     86018+0 records in
     86018+0 records out
     44041216 bytes (44 MB) copied, 13.0734 s, 3.4 MB/s
     [trz at empanada tmp]$ sudo eject /dev/sdb
                        </literallayout>
                    </para>
                </section>

                <section id='creating-an-image-based-on-core-image-minimal-and-crownbay-noemgd'>
                    <title>Creating an Image Based on <filename>core-image-minimal</filename> and <filename>crownbay-noemgd</filename></title>

                    <para>
                        This example creates an image based on
                        <filename>core-image-minimal</filename> and a
                        <filename>crownbay-noemgd</filename>
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
                        that works right out of the box.
                        <literallayout class='monospaced'>
     $ wic create directdisk -e core-image-minimal

     Checking basic build environment...
     Done.

     Creating image(s)...

     Info: The new image(s) can be found here:
      <replaceable>current_directory</replaceable>/build/directdisk-201309252350-sda.direct

     The following build artifacts were used to create the image(s):

     ROOTFS_DIR: /home/trz/yocto/yocto-image/build/tmp/work/crownbay_noemgd-poky-linux/core-image-minimal/1.0-r0/rootfs
     BOOTIMG_DIR: /home/trz/yocto/yocto-image/build/tmp/sysroots/crownbay-noemgd/usr/share
     KERNEL_DIR: /home/trz/yocto/yocto-image/build/tmp/sysroots/crownbay-noemgd/usr/src/kernel
     NATIVE_SYSROOT: /home/trz/yocto/yocto-image/build/tmp/sysroots/crownbay-noemgd/usr/src/kernel

     The image(s) were created using OE kickstart file:
      /home/trz/yocto/yocto-image/scripts/lib/image/canned-wks/directdisk.wks
                        </literallayout>
                    </para>
                </section>

                <section id='using-a-modified-kickstart-file-and-running-in-raw-mode'>
                    <title>Using a Modified Kickstart File and Running in Raw Mode</title>

                    <para>
                        This next example manually specifies each build artifact
                        (runs in Raw Mode) and uses a modified kickstart file.
                        The example also uses the <filename>-o</filename> option
                        to cause Wic to create the output
                        somewhere other than the default output directory,
                        which is the current directory:
                        <literallayout class='monospaced'>
     $ wic create ~/test.wks -o /home/trz/testwic --rootfs-dir \
          /home/trz/yocto/yocto-image/build/tmp/work/crownbay_noemgd-poky-linux/core-image-minimal/1.0-r0/rootfs \
          --bootimg-dir /home/trz/yocto/yocto-image/build/tmp/sysroots/crownbay-noemgd/usr/share \
          --kernel-dir /home/trz/yocto/yocto-image/build/tmp/sysroots/crownbay-noemgd/usr/src/kernel \
          --native-sysroot /home/trz/yocto/yocto-image/build/tmp/sysroots/x86_64-linux

     Creating image(s)...

     Info: The new image(s) can be found here:
      /home/trz/testwic/build/test-201309260032-sda.direct

     The following build artifacts were used to create the image(s):

     ROOTFS_DIR: /home/trz/yocto/yocto-image/build/tmp/work/crownbay_noemgd-poky-linux/core-image-minimal/1.0-r0/rootfs
     BOOTIMG_DIR: /home/trz/yocto/yocto-image/build/tmp/sysroots/crownbay-noemgd/usr/share
     KERNEL_DIR: /home/trz/yocto/yocto-image/build/tmp/sysroots/crownbay-noemgd/usr/src/kernel
     NATIVE_SYSROOT: /home/trz/yocto/yocto-image/build/tmp/sysroots/crownbay-noemgd/usr/src/kernel

     The image(s) were created using OE kickstart file:
      /home/trz/test.wks
                        </literallayout>
                        For this example,
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
                        did not have to be specified in the
                        <filename>local.conf</filename> file since the
                        artifact is manually specified.
                    </para>
                </section>
            </section>

            <section id='openembedded-kickstart-plugins'>
                <title>Plug-ins</title>

                <para>
                    Plug-ins allow Wic functionality to
                    be extended and specialized by users.
                    This section documents the plug-in interface, which is
                    currently restricted to source plug-ins.
                </para>

                <para>
                    Source plug-ins provide a mechanism to customize
                    various aspects of the image generation process in
                    Wic, mainly the contents of
                    partitions.
                    The plug-ins provide a mechanism for mapping values
                    specified in <filename>.wks</filename> files using the
                    <filename>--source</filename> keyword to a
                    particular plug-in implementation that populates a
                    corresponding partition.
                    <note>
                        If you use plug-ins that have build-time dependencies
                        (e.g. native tools, bootloaders, and so forth)
                        when building a Wic image, you need to specify those
                        dependencies using the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-WKS_FILE_DEPENDS'><filename>WKS_FILE_DEPENDS</filename></ulink>
                        variable.
                    </note>
                </para>

                <para>
                    A source plug-in is created as a subclass of
                    <filename>SourcePlugin</filename>.
                    The plug-in file containing it is added to
                    <filename>scripts/lib/wic/plugins/source/</filename> to
                    make the plug-in implementation available to the
                    Wic implementation.
                    For more information, see
                    <filename>scripts/lib/wic/pluginbase.py</filename>.
                </para>

                <para>
                    Source plug-ins can also be implemented and added by
                    external layers.
                    As such, any plug-ins found in a
                    <filename>scripts/lib/wic/plugins/source/</filename>
                    directory in an external layer are also made
                    available.
                </para>

                <para>
                    When the Wic implementation needs
                    to invoke a partition-specific implementation, it looks
                    for the plug-in that has the same name as the
                    <filename>--source</filename> parameter given to
                    that partition.
                    For example, if the partition is set up as follows:
                    <literallayout class='monospaced'>
     part /boot --source bootimg-pcbios   ...
                    </literallayout>
                    The methods defined as class members of the plug-in
                    having the matching <filename>bootimg-pcbios.name</filename>
                    class member are used.
                </para>

                <para>
                    To be more concrete, here is the plug-in definition that
                    matches a
                    <filename>--source bootimg-pcbios</filename> usage,
                    along with an example
                    method called by the Wic implementation
                    when it needs to invoke an implementation-specific
                    partition-preparation function:
                    <literallayout class='monospaced'>
    class BootimgPcbiosPlugin(SourcePlugin):
        name = 'bootimg-pcbios'

    @classmethod
        def do_prepare_partition(self, part, ...)
                    </literallayout>
                    If the subclass itself does not implement a function, a
                    default version in a superclass is located and
                    used, which is why all plug-ins must be derived from
                    <filename>SourcePlugin</filename>.
                </para>

                <para>
                    The <filename>SourcePlugin</filename> class defines the
                    following methods, which is the current set of methods
                    that can be implemented or overridden by
                    <filename>--source</filename> plug-ins.
                    Any methods not implemented by a
                    <filename>SourcePlugin</filename> subclass inherit the
                    implementations present in the
                    <filename>SourcePlugin</filename> class.
                    For more information, see the
                    <filename>SourcePlugin</filename> source for details:
                </para>

                <para>
                    <itemizedlist>
                        <listitem><para>
                            <emphasis><filename>do_prepare_partition()</filename>:</emphasis>
                            Called to do the actual content population for a
                            partition.
                            In other words, the method prepares the final
                            partition image that is incorporated into the
                            disk image.
                            </para></listitem>
                        <listitem><para>
                            <emphasis><filename>do_configure_partition()</filename>:</emphasis>
                            Called before
                            <filename>do_prepare_partition()</filename>.
                            This method is typically used to create custom
                            configuration files for a partition (e.g. syslinux
                            or grub configuration files).
                            </para></listitem>
                        <listitem><para>
                            <emphasis><filename>do_install_disk()</filename>:</emphasis>
                            Called after all partitions have been prepared and
                            assembled into a disk image.
                            This method provides a hook to allow finalization
                            of a disk image, (e.g. writing an MBR).
                            </para></listitem>
                        <listitem><para>
                            <emphasis><filename>do_stage_partition()</filename>:</emphasis>
                            Special content-staging hook called before
                            <filename>do_prepare_partition()</filename>.
                            This method is normally empty.</para>
                            <para>Typically, a partition just uses the passed-in
                            parameters (e.g. the unmodified value of
                            <filename>bootimg_dir</filename>).
                            However, in some cases things might need to be
                            more tailored.
                            As an example, certain files might additionally
                            need to be taken from
                            <filename>bootimg_dir + /boot</filename>.
                            This hook allows those files to be staged in a
                            customized fashion.
                            <note>
                                <filename>get_bitbake_var()</filename>
                                allows you to access non-standard variables
                                that you might want to use for this.
                            </note>
                            </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    This scheme is extensible.
                    Adding more hooks is a simple matter of adding more
                    plug-in methods to <filename>SourcePlugin</filename> and
                    derived classes.
                    The code that then needs to call the plug-in methods uses
                    <filename>plugin.get_source_plugin_methods()</filename>
                    to find the method or methods needed by the call.
                    Retrieval of those methods is accomplished
                    by filling up a dict with keys
                    containing the method names of interest.
                    On success, these will be filled in with the actual
                    methods.
                    Please see the Wic
                    implementation for examples and details.
                </para>
            </section>

            <section id='openembedded-kickstart-wks-reference'>
                <title>OpenEmbedded Kickstart (<filename>.wks</filename>) Reference</title>

                <para>
                    The current Wic implementation supports
                    only the basic kickstart partitioning commands:
                    <filename>partition</filename> (or <filename>part</filename>
                    for short) and <filename>bootloader</filename>.
                    <note>
                        Future updates will implement more commands and options.
                        If you use anything that is not specifically
                        supported, results can be unpredictable.
                    </note>
                </para>

                <para>
                    The following is a list of the commands, their syntax,
                    and meanings.
                    The commands are based on the Fedora
                    kickstart versions but with modifications to
                    reflect Wic capabilities.
                    You can see the original documentation for those commands
                    at the following links:
                    <itemizedlist>
                        <listitem><para>
                            <ulink url='http://fedoraproject.org/wiki/Anaconda/Kickstart#part_or_partition'>http://fedoraproject.org/wiki/Anaconda/Kickstart#part_or_partition</ulink>
                            </para></listitem>
                        <listitem><para>
                            <ulink url='http://fedoraproject.org/wiki/Anaconda/Kickstart#bootloader'>http://fedoraproject.org/wiki/Anaconda/Kickstart#bootloader</ulink>
                            </para></listitem>
                    </itemizedlist>
                </para>

                <section id='command-part-or-partition'>
                    <title>Command: part or partition</title>

                    <para>
                    Either of these commands create a partition on the system
                    and use the following syntax:
                        <literallayout class='monospaced'>
     part [<replaceable>mntpoint</replaceable>]
     partition [<replaceable>mntpoint</replaceable>]
                        </literallayout>
                        If you do not provide
                        <replaceable>mntpoint</replaceable>, Wic creates a
                        partition but does not mount it.
                    </para>

                    <para>
                        The
                        <filename><replaceable>mntpoint</replaceable></filename>
                        is where the partition will be mounted and must be of
                        one of the following forms:
                        <itemizedlist>
                            <listitem><para>
                                <filename>/<replaceable>path</replaceable></filename>:
                                For example, "/", "/usr", or "/home"
                                </para></listitem>
                            <listitem><para>
                                <filename>swap</filename>:
                                The created partition is used as swap space.
                                </para></listitem>
                        </itemizedlist>
                    </para>

                    <para>
                        Specifying a <replaceable>mntpoint</replaceable> causes
                        the partition to automatically be mounted.
                        Wic achieves this by adding entries to the filesystem
                        table (fstab) during image generation.
                        In order for wic to generate a valid fstab, you must
                        also provide one of the <filename>--ondrive</filename>,
                        <filename>--ondisk</filename>, or
                        <filename>--use-uuid</filename> partition options as
                        part of the command.
                        Here is an example using "/" as the mountpoint.
                        The command uses "--ondisk" to force the partition onto
                        the <filename>sdb</filename> disk:
                        <literallayout class='monospaced'>
     part / --source rootfs --ondisk sdb --fstype=ext3 --label platform --align 1024
                        </literallayout>
                    </para>

                    <para>
                        Here is a list that describes other supported options
                        you can use with the <filename>part</filename> and
                        <filename>partition</filename> commands:
                        <itemizedlist>
                            <listitem><para>
                                <emphasis><filename>--size</filename>:</emphasis>
                                The minimum partition size in MBytes.
                                Specify an integer value such as 500.
                                Do not append the number with "MB".
                                You do not need this option if you use
                                <filename>--source</filename>.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--source</filename>:</emphasis>
                                This option is a
                                Wic-specific option that
                                names the source of the data that populates
                                the partition.
                                The most common value for this option is
                                "rootfs", but you can use any value that maps to
                                a valid source plug-in.
                                For information on the source plug-ins, see the
                                "<link linkend='openembedded-kickstart-plugins'>Plug-ins</link>"
                                section.</para>
                                <para>If you use
                                <filename>--source rootfs</filename>,
                                Wic creates a partition as
                                large as needed and to fill it with the contents
                                of the root filesystem pointed to by the
                                <filename>-r</filename> command-line option
                                or the equivalent rootfs derived from the
                                <filename>-e</filename> command-line
                                option.
                                The filesystem type used to create the
                                partition is driven by the value of the
                                <filename>--fstype</filename> option
                                specified for the partition.
                                See the entry on
                                <filename>--fstype</filename> that
                                follows for more information.
                                </para>
                                <para>If you use
                                <filename>--source <replaceable>plugin-name</replaceable></filename>,
                                Wic creates a partition as
                                large as needed and fills it with the contents
                                of the partition that is generated by the
                                specified plug-in name using the data pointed
                                to by the <filename>-r</filename> command-line
                                option or the equivalent rootfs derived from the
                                <filename>-e</filename> command-line
                                option.
                                Exactly what those contents and filesystem type
                                end up being are dependent on the given plug-in
                                implementation.
                                </para>
                                <para>If you do not use the
                                <filename>--source</filename> option, the
                                <filename>wic</filename> command creates an
                                empty partition.
                                Consequently, you must use the
                                <filename>--size</filename> option to specify
                                the size of the empty partition.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--ondisk</filename> or <filename>--ondrive</filename>:</emphasis>
                                Forces the partition to be created on a
                                particular disk.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--fstype</filename>:</emphasis>
                                Sets the file system type for the partition.
                                Valid values are:
                                <itemizedlist>
                                    <listitem><para><filename>ext4</filename>
                                    </para></listitem>
                                    <listitem><para><filename>ext3</filename>
                                    </para></listitem>
                                    <listitem><para><filename>ext2</filename>
                                    </para></listitem>
                                    <listitem><para><filename>btrfs</filename>
                                    </para></listitem>
                                    <listitem><para><filename>squashfs</filename>
                                    </para></listitem>
                                    <listitem><para><filename>swap</filename>
                                    </para></listitem>
                                </itemizedlist>
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--fsoptions</filename>:</emphasis>
                                Specifies a free-form string of options to be
                                used when mounting the filesystem.
                                This string will be copied into the
                                <filename>/etc/fstab</filename> file of the
                                installed system and should be enclosed in
                                quotes.
                                If not specified, the default string
                                is "defaults".
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--label label</filename>:</emphasis>
                                Specifies the label to give to the filesystem to
                                be made on the partition.
                                If the given label is already in use by another
                                filesystem, a new label is created for the
                                partition.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--active</filename>:</emphasis>
                                Marks the partition as active.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--align (in KBytes)</filename>:</emphasis>
                                This option is a
                                Wic-specific option that
                                says to start a partition on an
                                <replaceable>x</replaceable> KBytes
                                boundary.</para></listitem>
                            <listitem><para>
                                <emphasis><filename>--no-table</filename>:</emphasis>
                                This option is a
                                Wic-specific option.
                                Using the option reserves space for the
                                partition and causes it to become populated.
                                However, the partition is not added to the
                                partition table.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--extra-space</filename>:</emphasis>
                                This option is a
                                Wic-specific option that
                                adds extra space after the space filled by the
                                content of the partition.
                                The final size can go beyond the size specified
                                by the <filename>--size</filename> option.
                                The default value is 10 Mbytes.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--overhead-factor</filename>:</emphasis>
                                This option is a
                                Wic-specific option that
                                multiplies the size of the partition by the
                                option's value.
                                You must supply a value greater than or equal to
                                "1".
                                The default value is "1.3".
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--part-type</filename>:</emphasis>
                                This option is a
                                Wic-specific option that
                                specifies the partition type globally
                                unique identifier (GUID) for GPT partitions.
                                You can find the list of partition type GUIDs
                                at
                                <ulink url='http://en.wikipedia.org/wiki/GUID_Partition_Table#Partition_type_GUIDs'></ulink>.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--use-uuid</filename>:</emphasis>
                                This option is a
                                Wic-specific option that
                                causes Wic to generate a
                                random GUID for the partition.
                                The generated identifier is used in the
                                bootloader configuration to specify the root
                                partition.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--uuid</filename>:</emphasis>
                                This option is a
                                Wic-specific
                                option that specifies the partition UUID.
                                </para></listitem>
                        </itemizedlist>
                    </para>
                </section>

                <section id='command-bootloader'>
                    <title>Command: bootloader</title>

                    <para>
                        This command specifies how the bootloader should be
                        configured and supports the following options:
                        <note>
                            Bootloader functionality and boot partitions are
                            implemented by the various
                            <filename>--source</filename>
                            plug-ins that implement bootloader functionality.
                            The bootloader command essentially provides a
                            means of modifying bootloader configuration.
                        </note>
                        <itemizedlist>
                            <listitem><para>
                                <emphasis><filename>--timeout</filename>:</emphasis>
                                Specifies the number of seconds before the
                                bootloader times out and boots the default
                                option.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--append</filename>:</emphasis>
                                Specifies kernel parameters.
                                These parameters will be added to the syslinux
                                <filename>APPEND</filename> or
                                <filename>grub</filename> kernel command line.
                                </para></listitem>
                            <listitem><para>
                                <emphasis><filename>--configfile</filename>:</emphasis>
                                Specifies a user-defined configuration file for
                                the bootloader.
                                You can provide a full pathname for the file or
                                a file that exists in the
                                <filename>canned-wks</filename> folder.
                                This option overrides all other bootloader
                                options.
                                </para></listitem>
                        </itemizedlist>
                    </para>
                </section>
            </section>
        </section>
    </section>

    <section id='building-an-initramfs-image'>
        <title>Building an Initial RAM Filesystem (initramfs) Image</title>

        <para>
            An initial RAM filesystem (initramfs) image provides a temporary
            root filesystem used for early system initialization (e.g.
            loading of modules needed to locate and mount the "real" root
            filesystem).
            <note>
                The initramfs image is the successor of initial RAM disk
                (initrd).
                It is a "copy in and out" (cpio) archive of the initial
                filesystem that gets loaded into memory during the Linux
                startup process.
                Because Linux uses the contents of the archive during
                initialization, the initramfs image needs to contain all of the
                device drivers and tools needed to mount the final root
                filesystem.
            </note>
        </para>

        <para>
            Follow these steps to create an initramfs image:
            <orderedlist>
                <listitem><para>
                    <emphasis>Create the initramfs Image Recipe:</emphasis>
                    You can reference the
                    <filename>core-image-minimal-initramfs.bb</filename>
                    recipe found in the <filename>meta/recipes-core</filename>
                    directory of the
                    <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
                    as an example from which to work.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Decide if You Need to Bundle the initramfs Image
                    Into the Kernel Image:</emphasis>
                    If you want the initramfs image that is built to be
                    bundled in with the kernel image, set the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-INITRAMFS_IMAGE_BUNDLE'><filename>INITRAMFS_IMAGE_BUNDLE</filename></ulink>
                    variable to "1" in your <filename>local.conf</filename>
                    configuration file and set the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-INITRAMFS_IMAGE'><filename>INITRAMFS_IMAGE</filename></ulink>
                    variable in the recipe that builds the kernel image.
                    <note><title>Tip</title>
                        It is recommended that you do bundle the initramfs
                        image with the kernel image to avoid circular
                        dependencies between the kernel recipe and the
                        initramfs recipe should the initramfs image
                        include kernel modules.
                    </note>
                    Setting the <filename>INITRAMFS_IMAGE_BUNDLE</filename>
                    flag causes the initramfs image to be unpacked
                    into the <filename>${B}/usr/</filename> directory.
                    The unpacked initramfs image is then passed to the kernel's
                    <filename>Makefile</filename> using the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-CONFIG_INITRAMFS_SOURCE'><filename>CONFIG_INITRAMFS_SOURCE</filename></ulink>
                    variable, allowing the initramfs image to be built into
                    the kernel normally.
                    <note>
                        If you choose to not bundle the initramfs image with
                        the kernel image, you are essentially using an
                        <ulink url='https://en.wikipedia.org/wiki/Initrd'>Initial RAM Disk (initrd)</ulink>.
                        Creating an initrd is handled primarily through the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-INITRD_IMAGE'><filename>INITRD_IMAGE</filename></ulink>,
                        <filename>INITRD_LIVE</filename>, and
                        <filename>INITRD_IMAGE_LIVE</filename> variables.
                        For more information, see the
                        <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/poky/tree/meta/classes/image-live.bbclass'><filename>image-live.bbclass</filename></ulink>
                        file.
                    </note>
                    </para></listitem>
<!--
Some notes from Cal:

    A non-bundled initramfs is essentially an initrd, which I am discovering
    to be rather confusingly supported in OE at the moment.

    Its primarily handled through INITRD_IMAGE(_LIVE/_VM) and INITRD(_LIVE/_VM)
    variables. INITRD_IMAGE* is the primary image target, which gets added to
    INITRD*, which is a list of cpio filesystems. You can add more cpio
    filesystems to the INITRD variable to add more to the initrd. For
    instance, meta-intel adds intel-microcode via the following:

        INITRD_LIVE_prepend = "${@bb.utils.contains('MACHINE_FEATURES', 'intel-ucode', '${DEPLOY_DIR_IMAGE}/microcode.cpio ', '', d)}"

    If 'intel-ucode' is in MACHINE_FEATURES, this resolves to:

        INITRD_LIVE_prepend = "${DEPLOY_DIR_IMAGE}/microcode.cpio "

    Unfortunately you need the full path, and its up to you to sort out
    dependencies as well. For instance, we have the following:

        MACHINE_ESSENTIAL_EXTRA_RDEPENDS_append = "${@bb.utils.contains('MACHINE_FEATURES', 'intel-ucode', ' intel-microcode', '', d)}"

    which resolves to:

        MACHINE_ESSENTIAL_EXTRA_RDEPENDS_append = "intel-microcode"

    However, the above is only true with the "live" IMAGE_FSTYPE. Wic is
    another beast entirely, with current wic kickstart files not supporting
    initrds, and only partial support in the source plugins. That being said,
    I know the generic bootfs work Ed is working on will help immensely in this
    aspect. He or Saul can provide more details here.

    Anyhow, its rather fractured and confusing and could probably use a
    rework honestly. I don't know how feasible it is to document all the
    details and corner cases of this area.
-->
                <listitem><para>
                    <emphasis>Optionally Add Items to the initramfs Image
                    Through the initramfs Image Recipe:</emphasis>
                    If you add items to the initramfs image by way of its
                    recipe, you should use
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_INSTALL'><filename>PACKAGE_INSTALL</filename></ulink>
                    rather than
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></ulink>.
                    <filename>PACKAGE_INSTALL</filename> gives more direct
                    control of what is added to the image as compared to
                    the defaults you might not necessarily want that are
                    set by the
                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-image'><filename>image</filename></ulink>
                    or
                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-core-image'><filename>core-image</filename></ulink>
                    classes.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Build the Kernel Image and the initramfs
                    Image:</emphasis>
                    Build your kernel image using BitBake.
                    Because the initramfs image recipe is a dependency of the
                    kernel image, the initramfs image is built as well and
                    bundled with the kernel image if you used the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-INITRAMFS_IMAGE_BUNDLE'><filename>INITRAMFS_IMAGE_BUNDLE</filename></ulink>
                    variable described earlier.
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

    <section id='flashing-images-using-bmaptool'>
        <title>Flashing Images Using <filename>bmaptool</filename></title>

        <para>
            An easy way to flash an image to a bootable device is to use
            <filename>bmaptool</filename>, which is integrated into the
            OpenEmbedded build system.
        </para>

        <para>
            Following, is an example that shows how to flash a Wic image.
            <note>
                You can use <filename>bmaptool</filename> to flash any
                type of image.
            </note>
            Use these steps to flash an image using
            <filename>bmaptool</filename>:
            <note>
                Unless you are able to install the
                <filename>bmap-tools</filename> package as mentioned in the note
                in the second bullet of step 3 further down, you will need to build
                <filename>bmaptool</filename> before using it.
                Build the tool using the following command:
                <literallayout class='monospaced'>
     $ bitbake bmap-tools-native
                </literallayout>
            </note>
            <orderedlist>
                <listitem><para>
                    <emphasis>Update the <filename>local.conf</filename> File:</emphasis>
                    Add the following to your <filename>local.conf</filename>
                    file:
                    <literallayout class='monospaced'>
     IMAGE_FSTYPES += "wic wic.bmap"
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Get Your Image:</emphasis>
                    Either have your image ready (pre-built) or take the step
                    build the image:
                    <literallayout class='monospaced'>
     $ bitbake <replaceable>image</replaceable>
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Flash the Device:</emphasis>
                    Flash the device with the image by using
                    <filename>bmaptool</filename> depending on your particular
                    setup:
                    <itemizedlist>
                        <listitem><para>
                            If you have write access to the media,
                            use this command form:
                            <literallayout class='monospaced'>
     $ oe-run-native bmap-tools-native bmaptool copy ./tmp/deploy/images/qemux86-64-core-image-minimal-<replaceable>machine</replaceable>.wic /dev/sd<replaceable>X</replaceable>
                            </literallayout>
                            </para></listitem>
                        <listitem><para>
                            If you do not have write access to
                            the media, use the following
                            commands:
                            <literallayout class='monospaced'>
     $ sudo chmod 666 /dev/sd<replaceable>X</replaceable>
     $ oe-run-native bmap-tools-native bmaptool copy ./tmp/deploy/images/qemux86-64-core-image-minimal-<replaceable>machine</replaceable>.wic /dev/sd<replaceable>X</replaceable>
                            </literallayout>
                            <note>
                                If you are using Ubuntu or Debian distributions,
                                you can install the
                                <filename>bmap-tools</filename> package using
                                the following command and then use the tool
                                without specifying
                                <filename>PATH</filename> even from the
                                root account:
                                <literallayout class='monospaced'>
     $ sudo apt-get install bmap-tools
                                </literallayout>
                            </note>
                            </para></listitem>
                    </itemizedlist>
                    </para></listitem>
            </orderedlist>
        </para>

        <para>
            For help on the <filename>bmaptool</filename> command, use the
            following command:
            <literallayout class='monospaced'>
     $ bmaptool --help
            </literallayout>
        </para>
    </section>

    <section id='configuring-the-kernel'>
        <title>Configuring the Kernel</title>

        <para>
            Configuring the Yocto Project kernel consists of making sure the
            <filename>.config</filename> file has all the right information
            in it for the image you are building.
            You can use the <filename>menuconfig</filename> tool and
            configuration fragments to make sure your
            <filename>.config</filename> file is just how you need it.
            You can also save known configurations in a
            <filename>defconfig</filename> file that the build system can use
            for kernel configuration.
        </para>

        <para>
            This section describes how to use <filename>menuconfig</filename>,
            create and use configuration fragments, and how to interactively
            modify your <filename>.config</filename> file to create the
            leanest kernel configuration file possible.
        </para>

        <para>
            For more information on kernel configuration, see the
            "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#changing-the-configuration'>Changing the Configuration</ulink>"
            section in the Yocto Project Linux Kernel Development Manual.
        </para>

        <section id='using-menuconfig'>
            <title>Using&nbsp;&nbsp;<filename>menuconfig</filename></title>

            <para>
                The easiest way to define kernel configurations is to set them through the
                <filename>menuconfig</filename> tool.
                This tool provides an interactive method with which
                to set kernel configurations.
                For general information on <filename>menuconfig</filename>, see
                <ulink url='http://en.wikipedia.org/wiki/Menuconfig'></ulink>.
            </para>

            <para>
                To use the <filename>menuconfig</filename> tool in the Yocto Project development
                environment, you must launch it using BitBake.
                Thus, the environment must be set up using the
                <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink>
                or
                <ulink url='&YOCTO_DOCS_REF_URL;#structure-memres-core-script'><filename>oe-init-build-env-memres</filename></ulink>
                script found in the
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
                You must also be sure of the state of your build in the
                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
                The following commands run <filename>menuconfig</filename>
                assuming the Source Directory's top-level folder is
                <filename>~/poky</filename>:
                <literallayout class='monospaced'>
     $ cd poky
     $ source oe-init-build-env
     $ bitbake linux-yocto -c kernel_configme -f
     $ bitbake linux-yocto -c menuconfig
                </literallayout>
                Once <filename>menuconfig</filename> comes up, its standard
                interface allows you to interactively examine and configure
                all the kernel configuration parameters.
                After making your changes, simply exit the tool and save your
                changes to create an updated version of the
                <filename>.config</filename> configuration file.
            </para>

            <para>
                Consider an example that configures the <filename>linux-yocto-3.14</filename>
                kernel.
                The OpenEmbedded build system recognizes this kernel as
                <filename>linux-yocto</filename>.
                Thus, the following commands from the shell in which you previously sourced the
                environment initialization script cleans the shared state cache and the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>
                directory and then runs <filename>menuconfig</filename>:
                <literallayout class='monospaced'>
     $ bitbake linux-yocto -c menuconfig
                </literallayout>
            </para>

            <para>
                Once <filename>menuconfig</filename> launches, use the interface
                to navigate through the selections to find the configuration settings in
                which you are interested.
                For example, consider the <filename>CONFIG_SMP</filename> configuration setting.
                You can find it at <filename>Processor Type and Features</filename> under
                the configuration selection <filename>Symmetric Multi-processing Support</filename>.
                After highlighting the selection, use the arrow keys to select or deselect
                the setting.
                When you are finished with all your selections, exit out and save them.
            </para>

            <para>
                Saving the selections updates the <filename>.config</filename> configuration file.
                This is the file that the OpenEmbedded build system uses to configure the
                kernel during the build.
                You can find and examine this file in the Build Directory in
                <filename>tmp/work/</filename>.
                The actual <filename>.config</filename> is located in the area where the
                specific kernel is built.
                For example, if you were building a Linux Yocto kernel based on the
                Linux 3.14 kernel and you were building a QEMU image targeted for
                <filename>x86</filename> architecture, the
                <filename>.config</filename> file would be located here:
                <literallayout class='monospaced'>
     poky/build/tmp/work/qemux86-poky-linux/linux-yocto-3.14.11+git1+84f...
        ...656ed30-r1/linux-qemux86-standard-build
                </literallayout>
                <note>
                    The previous example directory is artificially split and many of the characters
                    in the actual filename are omitted in order to make it more readable.
                    Also, depending on the kernel you are using, the exact pathname
                    for <filename>linux-yocto-3.14...</filename> might differ.
                </note>
            </para>

            <para>
                Within the <filename>.config</filename> file, you can see the kernel settings.
                For example, the following entry shows that symmetric multi-processor support
                is not set:
                <literallayout class='monospaced'>
     # CONFIG_SMP is not set
                </literallayout>
            </para>

            <para>
                A good method to isolate changed configurations is to use a combination of the
                <filename>menuconfig</filename> tool and simple shell commands.
                Before changing configurations with <filename>menuconfig</filename>, copy the
                existing <filename>.config</filename> and rename it to something else,
                use <filename>menuconfig</filename> to make
                as many changes as you want and save them, then compare the renamed configuration
                file against the newly created file.
                You can use the resulting differences as your base to create configuration fragments
                to permanently save in your kernel layer.
                <note>
                    Be sure to make a copy of the <filename>.config</filename> and don't just
                    rename it.
                    The build system needs an existing <filename>.config</filename>
                    from which to work.
                </note>
            </para>
        </section>

        <section id='creating-a-defconfig-file'>
            <title>Creating a&nbsp;&nbsp;<filename>defconfig</filename> File</title>

            <para>
                A <filename>defconfig</filename> file is simply a
                <filename>.config</filename> renamed to "defconfig".
                You can use a <filename>defconfig</filename> file
                to retain a known set of kernel configurations from which the
                OpenEmbedded build system can draw to create the final
                <filename>.config</filename> file.
                <note>
                    Out-of-the-box, the Yocto Project never ships a
                    <filename>defconfig</filename> or
                    <filename>.config</filename> file.
                    The OpenEmbedded build system creates the final
                    <filename>.config</filename> file used to configure the
                    kernel.
                </note>
            </para>

            <para>
                To create a <filename>defconfig</filename>, start with a
                complete, working Linux kernel <filename>.config</filename>
                file.
                Copy that file to the appropriate
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink><filename>}</filename>
                directory in your layer's
                <filename>recipes-kernel/linux</filename> directory, and rename
                the copied file to "defconfig".
                Then, add the following lines to the linux-yocto
                <filename>.bbappend</filename> file in your layer:
                <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
     SRC_URI += "file://defconfig"
                </literallayout>
                The
                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                tells the build system how to search for the file, while the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></ulink>
                extends the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESPATH'><filename>FILESPATH</filename></ulink>
                variable (search directories) to include the
                <filename>${PN}</filename> directory you created to hold the
                configuration changes.
                <note>
                    The build system applies the configurations from the
                    <filename>defconfig</filename> file before applying any
                    subsequent configuration fragments.
                    The final kernel configuration is a combination of the
                    configurations in the <filename>defconfig</filename>
                    file and any configuration fragments you provide.
                    You need to realize that if you have any configuration
                    fragments, the build system applies these on top of and
                    after applying the existing defconfig file configurations.
                </note>
                For more information on configuring the kernel, see the
                "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#changing-the-configuration'>Changing the Configuration</ulink>"
                and
                "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#generating-configuration-files'>Generating Configuration Files</ulink>"
                sections, both in the Yocto Project Linux Kernel Development
                Manual.
            </para>
        </section>

        <section id='creating-config-fragments'>
            <title>Creating Configuration Fragments</title>

            <para>
                Configuration fragments are simply kernel options that appear in a file
                placed where the OpenEmbedded build system can find and apply them.
                Syntactically, the configuration statement is identical to what would appear
                in the <filename>.config</filename> file, which is in the
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>:
                <literallayout class='monospaced'>
     tmp/work/<replaceable>arch</replaceable>-poky-linux/linux-yocto-<replaceable>release_specific_string</replaceable>/linux-<replaceable>arch</replaceable>-<replaceable>build_type</replaceable>
                </literallayout>
            </para>

            <para>
                It is simple to create a configuration fragment.
                For example, issuing the following from the shell creates a configuration fragment
                file named <filename>my_smp.cfg</filename> that enables multi-processor support
                within the kernel:
                <literallayout class='monospaced'>
     $ echo "CONFIG_SMP=y" >> my_smp.cfg
                </literallayout>
                <note>
                    All configuration fragment files must use the
                    <filename>.cfg</filename> extension in order for the
                    OpenEmbedded build system to recognize them as a
                    configuration fragment.
                </note>
            </para>

            <para>
                Where do you put your configuration fragment files?
                You can place these files in the same area pointed to by
                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>.
                The OpenEmbedded build system picks up the configuration and
                adds it to the kernel's configuration.
                For example, suppose you had a set of configuration options
                in a file called <filename>myconfig.cfg</filename>.
                If you put that file inside a directory named
                <filename>linux-yocto</filename> that resides in the same
                directory as the kernel's append file and then add a
                <filename>SRC_URI</filename> statement such as the following
                to the kernel's append file, those configuration options
                will be picked up and applied when the kernel is built.
                <literallayout class='monospaced'>
     SRC_URI += "file://myconfig.cfg"
                </literallayout>
            </para>

            <para>
                As mentioned earlier, you can group related configurations into multiple files and
                name them all in the <filename>SRC_URI</filename> statement as well.
                For example, you could group separate configurations specifically for Ethernet and graphics
                into their own files and add those by using a <filename>SRC_URI</filename> statement like the
                following in your append file:
                <literallayout class='monospaced'>
     SRC_URI += "file://myconfig.cfg \
            file://eth.cfg \
            file://gfx.cfg"
                </literallayout>
            </para>
        </section>

        <section id='fine-tuning-the-kernel-configuration-file'>
            <title>Fine-Tuning the Kernel Configuration File</title>

            <para>
                You can make sure the <filename>.config</filename> file is as lean or efficient as
                possible by reading the output of the kernel configuration fragment audit,
                noting any issues, making changes to correct the issues, and then repeating.
            </para>

            <para>
                As part of the kernel build process, the
                <filename>do_kernel_configcheck</filename> task runs.
                This task validates the kernel configuration by checking the final
                <filename>.config</filename> file against the input files.
                During the check, the task produces warning messages for the following
                issues:
                <itemizedlist>
                    <listitem><para>Requested options that did not make the final
                        <filename>.config</filename> file.</para></listitem>
                    <listitem><para>Configuration items that appear twice in the same
                        configuration fragment.</para></listitem>
                    <listitem><para>Configuration items tagged as "required" that were overridden.
                        </para></listitem>
                    <listitem><para>A board overrides a non-board specific option.</para></listitem>
                    <listitem><para>Listed options not valid for the kernel being processed.
                        In other words, the option does not appear anywhere.</para></listitem>
                </itemizedlist>
                <note>
                    The <filename>do_kernel_configcheck</filename> task can
                    also optionally report if an option is overridden during
                    processing.
                </note>
            </para>

            <para>
                For each output warning, a message points to the file
                that contains a list of the options and a pointer to the
                configuration fragment that defines them.
                Collectively, the files are the key to streamlining the
                configuration.
            </para>

            <para>
                To streamline the configuration, do the following:
                <orderedlist>
                    <listitem><para>Start with a full configuration that you
                        know works - it builds and boots successfully.
                        This configuration file will be your baseline.
                        </para></listitem>
                    <listitem><para>Separately run the
                        <filename>do_kernel_configme</filename> and
                        <filename>do_kernel_configcheck</filename> tasks.
                        </para></listitem>
                    <listitem><para>Take the resulting list of files from the
                        <filename>do_kernel_configcheck</filename> task
                        warnings and do the following:
                        <itemizedlist>
                            <listitem><para>
                                Drop values that are redefined in the fragment
                                but do not change the final
                                <filename>.config</filename> file.
                                </para></listitem>
                            <listitem><para>
                                Analyze and potentially drop values from the
                                <filename>.config</filename> file that override
                                required configurations.
                                </para></listitem>
                            <listitem><para>
                                Analyze and potentially remove non-board
                                specific options.
                                </para></listitem>
                            <listitem><para>
                                Remove repeated and invalid options.
                                </para></listitem>
                        </itemizedlist></para></listitem>
                    <listitem><para>
                        After you have worked through the output of the kernel
                        configuration audit, you can re-run the
                        <filename>do_kernel_configme</filename> and
                        <filename>do_kernel_configcheck</filename> tasks to
                        see the results of your changes.
                        If you have more issues, you can deal with them as
                        described in the previous step.
                        </para></listitem>
                </orderedlist>
            </para>

            <para>
                Iteratively working through steps two through four eventually yields
                a minimal, streamlined configuration file.
                Once you have the best <filename>.config</filename>, you can build the Linux
                Yocto kernel.
            </para>
        </section>

        <section id='determining-hardware-and-non-hardware-features-for-the-kernel-configuration-audit-phase'>
            <title>Determining Hardware and Non-Hardware Features for the Kernel Configuration Audit Phase</title>

            <para>
                This section describes part of the kernel configuration audit
                phase that most developers can ignore.
                During this part of the audit phase, the contents of the final
                <filename>.config</filename> file are compared against the
                fragments specified by the system.
                These fragments can be system fragments, distro fragments,
                or user specified configuration elements.
                Regardless of their origin, the OpenEmbedded build system
                warns the user if a specific option is not included in the
                final kernel configuration.
            </para>

            <para>
                In order to not overwhelm the user with configuration warnings,
                by default the system only reports on missing "hardware"
                options because a missing hardware option could mean a boot
                failure or that important hardware is not available.
            </para>

            <para>
                To determine whether or not a given option is "hardware" or
                "non-hardware", the kernel Metadata contains files that
                classify individual or groups of options as either hardware
                or non-hardware.
                To better show this, consider a situation where the
                Yocto Project kernel cache contains the following files:
                <literallayout class='monospaced'>
     kernel-cache/features/drm-psb/hardware.cfg
     kernel-cache/features/kgdb/hardware.cfg
     kernel-cache/ktypes/base/hardware.cfg
     kernel-cache/bsp/mti-malta32/hardware.cfg
     kernel-cache/bsp/fsl-mpc8315e-rdb/hardware.cfg
     kernel-cache/bsp/qemu-ppc32/hardware.cfg
     kernel-cache/bsp/qemuarma9/hardware.cfg
     kernel-cache/bsp/mti-malta64/hardware.cfg
     kernel-cache/bsp/arm-versatile-926ejs/hardware.cfg
     kernel-cache/bsp/common-pc/hardware.cfg
     kernel-cache/bsp/common-pc-64/hardware.cfg
     kernel-cache/features/rfkill/non-hardware.cfg
     kernel-cache/ktypes/base/non-hardware.cfg
     kernel-cache/features/aufs/non-hardware.kcf
     kernel-cache/features/ocf/non-hardware.kcf
     kernel-cache/ktypes/base/non-hardware.kcf
     kernel-cache/ktypes/base/hardware.kcf
     kernel-cache/bsp/qemu-ppc32/hardware.kcf
                </literallayout>
                The following list provides explanations for the various
                files:
                <itemizedlist>
                    <listitem><para><filename>hardware.kcf</filename>:
                        Specifies a list of kernel Kconfig files that contain
                        hardware options only.
                        </para></listitem>
                    <listitem><para><filename>non-hardware.kcf</filename>:
                        Specifies a list of kernel Kconfig files that contain
                        non-hardware options only.
                        </para></listitem>
                    <listitem><para><filename>hardware.cfg</filename>:
                        Specifies a list of kernel
                        <filename>CONFIG_</filename> options that are hardware,
                        regardless of whether or not they are within a Kconfig
                        file specified by a hardware or non-hardware
                        Kconfig file (i.e. <filename>hardware.kcf</filename> or
                        <filename>non-hardware.kcf</filename>).
                        </para></listitem>
                    <listitem><para><filename>non-hardware.cfg</filename>:
                        Specifies a list of kernel
                        <filename>CONFIG_</filename> options that are
                        not hardware, regardless of whether or not they are
                        within a Kconfig file specified by a hardware or
                        non-hardware Kconfig file (i.e.
                        <filename>hardware.kcf</filename> or
                        <filename>non-hardware.kcf</filename>).
                        </para></listitem>
                </itemizedlist>
                Here is a specific example using the
                <filename>kernel-cache/bsp/mti-malta32/hardware.cfg</filename>:
                <literallayout class='monospaced'>
     CONFIG_SERIAL_8250
     CONFIG_SERIAL_8250_CONSOLE
     CONFIG_SERIAL_8250_NR_UARTS
     CONFIG_SERIAL_8250_PCI
     CONFIG_SERIAL_CORE
     CONFIG_SERIAL_CORE_CONSOLE
     CONFIG_VGA_ARB
                </literallayout>
                The kernel configuration audit automatically detects these
                files (hence the names must be exactly the ones discussed here),
                and uses them as inputs when generating warnings about the
                final <filename>.config</filename> file.
            </para>

            <para>
                A user-specified kernel Metadata repository, or recipe space
                feature, can use these same files to classify options that are
                found within its <filename>.cfg</filename> files as hardware
                or non-hardware, to prevent the OpenEmbedded build system from
                producing an error or warning when an option is not in the
                final <filename>.config</filename> file.
            </para>
        </section>
    </section>

    <section id='making-images-more-secure'>
        <title>Making Images More Secure</title>

        <para>
            Security is of increasing concern for embedded devices.
            Consider the issues and problems discussed in just this
            sampling of work found across the Internet:
            <itemizedlist>
                <listitem><para><emphasis>
                    "<ulink url='https://www.schneier.com/blog/archives/2014/01/security_risks_9.html'>Security Risks of Embedded Systems</ulink>"</emphasis>
                    by Bruce Schneier
                    </para></listitem>
                <listitem><para><emphasis>
                    "<ulink url='http://internetcensus2012.bitbucket.org/paper.html'>Internet Census 2012</ulink>"</emphasis>
                    by Carna Botnet</para></listitem>
                <listitem><para><emphasis>
                    "<ulink url='http://elinux.org/images/6/6f/Security-issues.pdf'>Security Issues for Embedded Devices</ulink>"</emphasis>
                    by Jake Edge
                    </para></listitem>
            </itemizedlist>
        </para>

        <para>
            When securing your image is of concern, there are steps, tools,
            and variables that you can consider to help you reach the
            security goals you need for your particular device.
            Not all situations are identical when it comes to making an
            image secure.
            Consequently, this section provides some guidance and suggestions
            for consideration when you want to make your image more secure.
            <note>
                Because the security requirements and risks are
                different for every type of device, this section cannot
                provide a complete reference on securing your custom OS.
                It is strongly recommended that you also consult other sources
                of information on embedded Linux system hardening and on
                security.
            </note>
        </para>

        <section id='general-considerations'>
            <title>General Considerations</title>

            <para>
                General considerations exist that help you create more
                secure images.
                You should consider the following suggestions to help
                make your device more secure:
                <itemizedlist>
                    <listitem><para>
                        Scan additional code you are adding to the system
                        (e.g. application code) by using static analysis
                        tools.
                        Look for buffer overflows and other potential
                        security problems.
                    </para></listitem>
                    <listitem><para>
                        Pay particular attention to the security for
                        any web-based administration interface.
                        </para>
                        <para>Web interfaces typically need to perform
                        administrative functions and tend to need to run with
                        elevated privileges.
                        Thus, the consequences resulting from the interface's
                        security becoming compromised can be serious.
                        Look for common web vulnerabilities such as
                        cross-site-scripting (XSS), unvalidated inputs,
                        and so forth.</para>
                        <para>As with system passwords, the default credentials
                        for accessing a web-based interface should not be the
                        same across all devices.
                        This is particularly true if the interface is enabled
                        by default as it can be assumed that many end-users
                        will not change the credentials.
                    </para></listitem>
                    <listitem><para>
                        Ensure you can update the software on the device to
                        mitigate vulnerabilities discovered in the future.
                        This consideration especially applies when your
                        device is network-enabled.
                    </para></listitem>
                    <listitem><para>
                        Ensure you remove or disable debugging functionality
                        before producing the final image.
                        For information on how to do this, see the
                        "<link linkend='considerations-specific-to-the-openembedded-build-system'>Considerations Specific to the OpenEmbedded Build System</link>"
                        section.
                        </para></listitem>
                    <listitem><para>
                        Ensure you have no network services listening that
                        are not needed.
                    </para></listitem>
                    <listitem><para>
                        Remove any software from the image that is not needed.
                    </para></listitem>
                    <listitem><para>
                        Enable hardware support for secure boot functionality
                        when your device supports this functionality.
                    </para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='security-flags'>
            <title>Security Flags</title>

            <para>
                The Yocto Project has security flags that you can enable that
                help make your build output more secure.
                The security flags are in the
                <filename>meta/conf/distro/include/security_flags.inc</filename>
                file in your
                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
                (e.g. <filename>poky</filename>).
                <note>
                    Depending on the recipe, certain security flags are enabled
                    and disabled by default.
                </note>
            </para>

            <para>
<!--
                The GCC/LD flags in <filename>security_flags.inc</filename>
                enable more secure code generation.
                By including the <filename>security_flags.inc</filename>
                file, you enable flags to the compiler and linker that cause
                them to generate more secure code.
                <note>
                    The GCC/LD flags are enabled by default in the
                    <filename>poky-lsb</filename> distribution.
                </note>
-->
                Use the following line in your
                <filename>local.conf</filename> file or in your custom
                distribution configuration file to enable the security
                compiler and linker flags for your build:
                <literallayout class='monospaced'>
     require conf/distro/include/security_flags.inc
                </literallayout>
            </para>
        </section>

        <section id='considerations-specific-to-the-openembedded-build-system'>
            <title>Considerations Specific to the OpenEmbedded Build System</title>

            <para>
                You can take some steps that are specific to the
                OpenEmbedded build system to make your images more secure:
                <itemizedlist>
                    <listitem><para>
                        Ensure "debug-tweaks" is not one of your selected
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></ulink>.
                        When creating a new project, the default is to provide you
                        with an initial <filename>local.conf</filename> file that
                        enables this feature using the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_IMAGE_FEATURES'><filename>EXTRA_IMAGE_FEATURES</filename></ulink> variable with the line:
                <literallayout class='monospaced'>
     EXTRA_IMAGE_FEATURES = "debug-tweaks"
                </literallayout>
                        To disable that feature, simply comment out that line in your
                        <filename>local.conf</filename> file, or
                        make sure <filename>IMAGE_FEATURES</filename> does not contain
                        "debug-tweaks" before producing your final image.
                        Among other things, leaving this in place sets the
                        root password as blank, which makes logging in for
                        debugging or inspection easy during
                        development but also means anyone can easily log in
                        during production.
                        </para></listitem>
                    <listitem><para>
                        It is possible to set a root password for the image
                        and also to set passwords for any extra users you might
                        add (e.g. administrative or service type users).
                        When you set up passwords for multiple images or
                        users, you should not duplicate passwords.
                        </para>
                        <para>
                        To set up passwords, use the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-extrausers'><filename>extrausers</filename></ulink>
                        class, which is the preferred method.
                        For an example on how to set up both root and user
                        passwords, see the
                        "<ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-extrausers'><filename>extrausers.bbclass</filename></ulink>"
                        section.
                        <note>
                            When adding extra user accounts or setting a
                            root password, be cautious about setting the
                            same password on every device.
                            If you do this, and the password you have set
                            is exposed, then every device is now potentially
                            compromised.
                            If you need this access but want to ensure
                            security, consider setting a different,
                            random password for each device.
                            Typically, you do this as a separate step after
                            you deploy the image onto the device.
                        </note>
                        </para></listitem>
                    <listitem><para>
                        Consider enabling a Mandatory Access Control (MAC)
                        framework such as SMACK or SELinux and tuning it
                        appropriately for your device's usage.
                        You can find more information in the
                        <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi/meta-selinux/'><filename>meta-selinux</filename></ulink>
                        layer.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
            </para>
        </section>

        <section id='tools-for-hardening-your-image'>
            <title>Tools for Hardening Your Image</title>

            <para>
                The Yocto Project provides tools for making your image
                more secure.
                You can find these tools in the
                <filename>meta-security</filename> layer of the
                <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi'>Yocto Project Source Repositories</ulink>.
            </para>
        </section>
    </section>

    <section id='creating-your-own-distribution'>
        <title>Creating Your Own Distribution</title>

        <para>
            When you build an image using the Yocto Project and
            do not alter any distribution
            <ulink url='&YOCTO_DOCS_REF_URL;#metadata'>Metadata</ulink>,
            you are creating a Poky distribution.
            If you wish to gain more control over package alternative
            selections, compile-time options, and other low-level
            configurations, you can create your own distribution.
        </para>

        <para>
            To create your own distribution, the basic steps consist of
            creating your own distribution layer, creating your own
            distribution configuration file, and then adding any needed
            code and Metadata to the layer.
            The following steps provide some more detail:
            <itemizedlist>
                <listitem><para><emphasis>Create a layer for your new distro:</emphasis>
                    Create your distribution layer so that you can keep your
                    Metadata and code for the distribution separate.
                    It is strongly recommended that you create and use your own
                    layer for configuration and code.
                    Using your own layer as compared to just placing
                    configurations in a <filename>local.conf</filename>
                    configuration file makes it easier to reproduce the same
                    build configuration when using multiple build machines.
                    See the
                    "<link linkend='creating-a-general-layer-using-the-yocto-layer-script'>Creating a General Layer Using the yocto-layer Script</link>"
                    section for information on how to quickly set up a layer.
                    </para></listitem>
                <listitem><para><emphasis>Create the distribution configuration file:</emphasis>
                    The distribution configuration file needs to be created in
                    the <filename>conf/distro</filename> directory of your
                    layer.
                    You need to name it using your distribution name
                    (e.g. <filename>mydistro.conf</filename>).
                    <note>
                        The
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO'><filename>DISTRO</filename></ulink>
                        variable in your
                        <filename>local.conf</filename> file determines the
                        name of your distribution.
                    </note></para>
                    <para>You can split out parts of your configuration file
                    into include files and then "require" them from within
                    your distribution configuration file.
                    Be sure to place the include files in the
                    <filename>conf/distro/include</filename> directory of
                    your layer.
                    A common example usage of include files would be to
                    separate out the selection of desired version and revisions
                    for individual recipes.
</para>
                    <para>Your configuration file needs to set the following
                    required variables:
                    <literallayout class='monospaced'>
     <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_NAME'><filename>DISTRO_NAME</filename></ulink>
     <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_VERSION'><filename>DISTRO_VERSION</filename></ulink>
                    </literallayout>
                    These following variables are optional and you typically
                    set them from the distribution configuration file:
                    <literallayout class='monospaced'>
     <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></ulink>
     <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_EXTRA_RDEPENDS'><filename>DISTRO_EXTRA_RDEPENDS</filename></ulink>
     <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_EXTRA_RRECOMMENDS'><filename>DISTRO_EXTRA_RRECOMMENDS</filename></ulink>
     <ulink url='&YOCTO_DOCS_REF_URL;#var-TCLIBC'><filename>TCLIBC</filename></ulink>
                    </literallayout>
                    <tip>
                        If you want to base your distribution configuration file
                        on the very basic configuration from OE-Core, you
                        can use
                        <filename>conf/distro/defaultsetup.conf</filename> as
                        a reference and just include variables that differ
                        as compared to <filename>defaultsetup.conf</filename>.
                        Alternatively, you can create a distribution
                        configuration file from scratch using the
                        <filename>defaultsetup.conf</filename> file
                        or configuration files from other distributions
                        such as Poky or Angstrom as references.
                    </tip></para></listitem>
                <listitem><para><emphasis>Provide miscellaneous variables:</emphasis>
                    Be sure to define any other variables for which you want to
                    create a default or enforce as part of the distribution
                    configuration.
                    You can include nearly any variable from the
                    <filename>local.conf</filename> file.
                    The variables you use are not limited to the list in the
                    previous bulleted item.</para></listitem>
                <listitem><para><emphasis>Point to Your distribution configuration file:</emphasis>
                    In your <filename>local.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>,
                    set your
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO'><filename>DISTRO</filename></ulink>
                    variable to point to your distribution's configuration file.
                    For example, if your distribution's configuration file is
                    named <filename>mydistro.conf</filename>, then you point
                    to it as follows:
                    <literallayout class='monospaced'>
     DISTRO = "mydistro"
                    </literallayout></para></listitem>
                <listitem><para><emphasis>Add more to the layer if necessary:</emphasis>
                    Use your layer to hold other information needed for the
                    distribution:
                    <itemizedlist>
                        <listitem><para>Add recipes for installing
                            distro-specific configuration files that are not
                            already installed by another recipe.
                            If you have distro-specific configuration files
                            that are included by an existing recipe, you should
                            add an append file (<filename>.bbappend</filename>)
                            for those.
                            For general information and recommendations
                            on how to add recipes to your layer, see the
                            "<link linkend='creating-your-own-layer'>Creating Your Own Layer</link>"
                            and
                            "<link linkend='best-practices-to-follow-when-creating-layers'>Following Best Practices When Creating Layers</link>"
                            sections.</para></listitem>
                        <listitem><para>Add any image recipes that are specific
                            to your distribution.</para></listitem>
                        <listitem><para>Add a <filename>psplash</filename>
                            append file for a branded splash screen.
                            For information on append files, see the
                            "<link linkend='using-bbappend-files'>Using .bbappend Files in Your Layer</link>"
                            section.</para></listitem>
                        <listitem><para>Add any other append files to make
                            custom changes that are specific to individual
                            recipes.</para></listitem>
                    </itemizedlist></para></listitem>
            </itemizedlist>
        </para>
    </section>

    <section id='creating-a-custom-template-configuration-directory'>
        <title>Creating a Custom Template Configuration Directory</title>

        <para>
            If you are producing your own customized version
            of the build system for use by other users, you might
            want to customize the message shown by the setup script or
            you might want to change the template configuration files (i.e.
            <filename>local.conf</filename> and
            <filename>bblayers.conf</filename>) that are created in
            a new build directory.
        </para>

        <para>
            The OpenEmbedded build system uses the environment variable
            <filename>TEMPLATECONF</filename> to locate the directory
            from which it gathers configuration information that ultimately
            ends up in the
            <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
            <filename>conf</filename> directory.
            By default, <filename>TEMPLATECONF</filename> is set as
            follows in the <filename>poky</filename> repository:
            <literallayout class='monospaced'>
     TEMPLATECONF=${TEMPLATECONF:-meta-poky/conf}
            </literallayout>
            This is the directory used by the build system to find templates
            from which to build some key configuration files.
            If you look at this directory, you will see the
            <filename>bblayers.conf.sample</filename>,
            <filename>local.conf.sample</filename>, and
            <filename>conf-notes.txt</filename> files.
            The build system uses these files to form the respective
            <filename>bblayers.conf</filename> file,
            <filename>local.conf</filename> file, and display the list of
            BitBake targets when running the setup script.
        </para>

        <para>
            To override these default configuration files with
            configurations you want used within every new
            Build Directory, simply set the
            <filename>TEMPLATECONF</filename> variable to your directory.
            The <filename>TEMPLATECONF</filename> variable is set in the
            <filename>.templateconf</filename> file, which is in the
            top-level
            <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
            folder (e.g. <filename>poky</filename>).
            Edit the <filename>.templateconf</filename> so that it can locate
            your directory.
        </para>

        <para>
            Best practices dictate that you should keep your
            template configuration directory in your custom distribution layer.
            For example, suppose you have a layer named
            <filename>meta-mylayer</filename> located in your home directory
            and you want your template configuration directory named
            <filename>myconf</filename>.
            Changing the <filename>.templateconf</filename> as follows
            causes the OpenEmbedded build system to look in your directory
            and base its configuration files on the
            <filename>*.sample</filename> configuration files it finds.
            The final configuration files (i.e.
            <filename>local.conf</filename> and
            <filename>bblayers.conf</filename> ultimately still end up in
            your Build Directory, but they are based on your
            <filename>*.sample</filename> files.
            <literallayout class='monospaced'>
     TEMPLATECONF=${TEMPLATECONF:-meta-mylayer/myconf}
            </literallayout>
        </para>

        <para>
            Aside from the <filename>*.sample</filename> configuration files,
            the <filename>conf-notes.txt</filename> also resides in the
            default <filename>meta-poky/conf</filename> directory.
            The scripts that set up the build environment
            (i.e.
            <ulink url="&YOCTO_DOCS_REF_URL;#structure-core-script"><filename>&OE_INIT_FILE;</filename></ulink>
            and
            <ulink url="&YOCTO_DOCS_REF_URL;#structure-memres-core-script"><filename>oe-init-build-env-memres</filename></ulink>)
            use this file to display BitBake targets as part of the script
            output.
            Customizing this <filename>conf-notes.txt</filename> file is a
            good way to make sure your list of custom targets appears
            as part of the script's output.
        </para>

        <para>
            Here is the default list of targets displayed as a result of
            running either of the setup scripts:
            <literallayout class='monospaced'>
     You can now run 'bitbake &lt;target&gt;'

     Common targets are:
         core-image-minimal
         core-image-sato
         meta-toolchain
         meta-ide-support
            </literallayout>
        </para>

        <para>
            Changing the listed common targets is as easy as editing your
            version of <filename>conf-notes.txt</filename> in your
            custom template configuration directory and making sure you
            have <filename>TEMPLATECONF</filename> set to your directory.
        </para>
    </section>

    <section id='building-a-tiny-system'>
        <title>Building a Tiny System</title>

        <para>
            Very small distributions have some significant advantages such
            as requiring less on-die or in-package memory (cheaper), better
            performance through efficient cache usage, lower power requirements
            due to less memory, faster boot times, and reduced development
            overhead.
            Some real-world examples where a very small distribution gives
            you distinct advantages are digital cameras, medical devices,
            and small headless systems.
        </para>

        <para>
            This section presents information that shows you how you can
            trim your distribution to even smaller sizes than the
            <filename>poky-tiny</filename> distribution, which is around
            5 Mbytes, that can be built out-of-the-box using the Yocto Project.
        </para>

        <section id='tiny-system-overview'>
            <title>Overview</title>

            <para>
                The following list presents the overall steps you need to
                consider and perform to create distributions with smaller
                root filesystems, achieve faster boot times, maintain your critical
                functionality, and avoid initial RAM disks:
                <itemizedlist>
                    <listitem><para>
                        <link linkend='goals-and-guiding-principles'>Determine your goals and guiding principles.</link>
                        </para></listitem>
                    <listitem><para>
                        <link linkend='understand-what-gives-your-image-size'>Understand what contributes to your image size.</link>
                        </para></listitem>
                    <listitem><para>
                        <link linkend='trim-the-root-filesystem'>Reduce the size of the root filesystem.</link>
                        </para></listitem>
                    <listitem><para>
                        <link linkend='trim-the-kernel'>Reduce the size of the kernel.</link>
                        </para></listitem>
                    <listitem><para>
                        <link linkend='remove-package-management-requirements'>Eliminate packaging requirements.</link>
                        </para></listitem>
                    <listitem><para>
                        <link linkend='look-for-other-ways-to-minimize-size'>Look for other ways to minimize size.</link>
                        </para></listitem>
                    <listitem><para>
                        <link linkend='iterate-on-the-process'>Iterate on the process.</link>
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='goals-and-guiding-principles'>
            <title>Goals and Guiding Principles</title>

            <para>
                Before you can reach your destination, you need to know
                where you are going.
                Here is an example list that you can use as a guide when
                creating very small distributions:
                <itemizedlist>
                    <listitem><para>Determine how much space you need
                        (e.g. a kernel that is 1 Mbyte or less and
                        a root filesystem that is 3 Mbytes or less).
                        </para></listitem>
                    <listitem><para>Find the areas that are currently
                        taking 90% of the space and concentrate on reducing
                        those areas.
                        </para></listitem>
                    <listitem><para>Do not create any difficult "hacks"
                        to achieve your goals.</para></listitem>
                    <listitem><para>Leverage the device-specific
                        options.</para></listitem>
                    <listitem><para>Work in a separate layer so that you
                        keep changes isolated.
                        For information on how to create layers, see
                        the "<link linkend='understanding-and-creating-layers'>Understanding and Creating Layers</link>" section.
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='understand-what-gives-your-image-size'>
            <title>Understand What Contributes to Your Image Size</title>

            <para>
                It is easiest to have something to start with when creating
                your own distribution.
                You can use the Yocto Project out-of-the-box to create the
                <filename>poky-tiny</filename> distribution.
                Ultimately, you will want to make changes in your own
                distribution that are likely modeled after
                <filename>poky-tiny</filename>.
                <note>
                    To use <filename>poky-tiny</filename> in your build,
                    set the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO'><filename>DISTRO</filename></ulink>
                    variable in your
                    <filename>local.conf</filename> file to "poky-tiny"
                    as described in the
                    "<link linkend='creating-your-own-distribution'>Creating Your Own Distribution</link>"
                    section.
                </note>
            </para>

            <para>
                Understanding some memory concepts will help you reduce the
                system size.
                Memory consists of static, dynamic, and temporary memory.
                Static memory is the TEXT (code), DATA (initialized data
                in the code), and BSS (uninitialized data) sections.
                Dynamic memory represents memory that is allocated at runtime:
                stacks, hash tables, and so forth.
                Temporary memory is recovered after the boot process.
                This memory consists of memory used for decompressing
                the kernel and for the <filename>__init__</filename>
                functions.
            </para>

            <para>
                To help you see where you currently are with kernel and root
                filesystem sizes, you can use two tools found in the
                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink> in
                the <filename>scripts/tiny/</filename> directory:
                <itemizedlist>
                    <listitem><para><filename>ksize.py</filename>: Reports
                        component sizes for the kernel build objects.
                        </para></listitem>
                    <listitem><para><filename>dirsize.py</filename>: Reports
                        component sizes for the root filesystem.</para></listitem>
                </itemizedlist>
                This next tool and command help you organize configuration
                fragments and view file dependencies in a human-readable form:
                <itemizedlist>
                    <listitem><para><filename>merge_config.sh</filename>:
                        Helps you manage configuration files and fragments
                        within the kernel.
                        With this tool, you can merge individual configuration
                        fragments together.
                        The tool allows you to make overrides and warns you
                        of any missing configuration options.
                        The tool is ideal for allowing you to iterate on
                        configurations, create minimal configurations, and
                        create configuration files for different machines
                        without having to duplicate your process.</para>
                        <para>The <filename>merge_config.sh</filename> script is
                        part of the Linux Yocto kernel Git repositories
                        (i.e. <filename>linux-yocto-3.14</filename>,
                        <filename>linux-yocto-3.10</filename>,
                        <filename>linux-yocto-3.8</filename>, and so forth)
                        in the
                        <filename>scripts/kconfig</filename> directory.</para>
                        <para>For more information on configuration fragments,
                        see the
                        "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#generating-configuration-files'>Generating Configuration Files</ulink>"
                        section of the Yocto Project Linux Kernel Development
                        Manual and the "<link linkend='creating-config-fragments'>Creating Configuration Fragments</link>"
                        section, which is in this manual.</para></listitem>
                    <listitem><para><filename>bitbake -u taskexp -g <replaceable>bitbake_target</replaceable></filename>:
                        Using the BitBake command with these options brings up
                        a Dependency Explorer from which you can view file
                        dependencies.
                        Understanding these dependencies allows you to make
                        informed decisions when cutting out various pieces of the
                        kernel and root filesystem.</para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='trim-the-root-filesystem'>
            <title>Trim the Root Filesystem</title>

            <para>
                The root filesystem is made up of packages for booting,
                libraries, and applications.
                To change things, you can configure how the packaging happens,
                which changes the way you build them.
                You can also modify the filesystem itself or select a different
                filesystem.
            </para>

            <para>
                First, find out what is hogging your root filesystem by running the
                <filename>dirsize.py</filename> script from your root directory:
                <literallayout class='monospaced'>
     $ cd <replaceable>root-directory-of-image</replaceable>
     $ dirsize.py 100000 > dirsize-100k.log
     $ cat dirsize-100k.log
                </literallayout>
                You can apply a filter to the script to ignore files under
                a certain size.
                The previous example filters out any files below 100 Kbytes.
                The sizes reported by the tool are uncompressed, and thus
                will be smaller by a relatively constant factor in a
                compressed root filesystem.
                When you examine your log file, you can focus on areas of the
                root filesystem that take up large amounts of memory.
            </para>

            <para>
                You need to be sure that what you eliminate does not cripple
                the functionality you need.
                One way to see how packages relate to each other is by using
                the Dependency Explorer UI with the BitBake command:
                <literallayout class='monospaced'>
     $ cd <replaceable>image-directory</replaceable>
     $ bitbake -u taskexp -g <replaceable>image</replaceable>
                </literallayout>
                Use the interface to select potential packages you wish to
                eliminate and see their dependency relationships.
            </para>

            <para>
                When deciding how to reduce the size, get rid of packages that
                result in minimal impact on the feature set.
                For example, you might not need a VGA display.
                Or, you might be able to get by with <filename>devtmpfs</filename>
                and <filename>mdev</filename> instead of
                <filename>udev</filename>.
            </para>

            <para>
                Use your <filename>local.conf</filename> file to make changes.
                For example, to eliminate <filename>udev</filename> and
                <filename>glib</filename>, set the following in the
                local configuration file:
                <literallayout class='monospaced'>
     VIRTUAL-RUNTIME_dev_manager = ""
                </literallayout>
            </para>

            <para>
                Finally, you should consider exactly the type of root
                filesystem you need to meet your needs while also reducing
                its size.
                For example, consider <filename>cramfs</filename>,
                <filename>squashfs</filename>, <filename>ubifs</filename>,
                <filename>ext2</filename>, or an <filename>initramfs</filename>
                using <filename>initramfs</filename>.
                Be aware that <filename>ext3</filename> requires a 1 Mbyte
                journal.
                If you are okay with running read-only, you do not need this
                journal.
            </para>

            <note>
                After each round of elimination, you need to rebuild your
                system and then use the tools to see the effects of your
                reductions.
            </note>


        </section>

        <section id='trim-the-kernel'>
            <title>Trim the Kernel</title>

            <para>
                The kernel is built by including policies for hardware-independent
                aspects.
                What subsystems do you enable?
                For what architecture are you building?
                Which drivers do you build by default?
                <note>You can modify the kernel source if you want to help
                    with boot time.
                </note>
            </para>

            <para>
                Run the <filename>ksize.py</filename> script from the top-level
                Linux build directory to get an idea of what is making up
                the kernel:
                <literallayout class='monospaced'>
     $ cd <replaceable>top-level-linux-build-directory</replaceable>
     $ ksize.py > ksize.log
     $ cat ksize.log
                </literallayout>
                When you examine the log, you will see how much space is
                taken up with the built-in <filename>.o</filename> files for
                drivers, networking, core kernel files, filesystem, sound,
                and so forth.
                The sizes reported by the tool are uncompressed, and thus
                will be smaller by a relatively constant factor in a compressed
                kernel image.
                Look to reduce the areas that are large and taking up around
                the "90% rule."
            </para>

            <para>
                To examine, or drill down, into any particular area, use the
                <filename>-d</filename> option with the script:
                <literallayout class='monospaced'>
     $ ksize.py -d > ksize.log
                </literallayout>
                Using this option breaks out the individual file information
                for each area of the kernel (e.g. drivers, networking, and
                so forth).
            </para>

            <para>
                Use your log file to see what you can eliminate from the kernel
                based on features you can let go.
                For example, if you are not going to need sound, you do not
                need any drivers that support sound.
            </para>

            <para>
                After figuring out what to eliminate, you need to reconfigure
                the kernel to reflect those changes during the next build.
                You could run <filename>menuconfig</filename> and make all your
                changes at once.
                However, that makes it difficult to see the effects of your
                individual eliminations and also makes it difficult to replicate
                the changes for perhaps another target device.
                A better method is to start with no configurations using
                <filename>allnoconfig</filename>, create configuration
                fragments for individual changes, and then manage the
                fragments into a single configuration file using
                <filename>merge_config.sh</filename>.
                The tool makes it easy for you to iterate using the
                configuration change and build cycle.
            </para>

            <para>
                Each time you make configuration changes, you need to rebuild
                the kernel and check to see what impact your changes had on
                the overall size.
            </para>
        </section>

        <section id='remove-package-management-requirements'>
            <title>Remove Package Management Requirements</title>

            <para>
                Packaging requirements add size to the image.
                One way to reduce the size of the image is to remove all the
                packaging requirements from the image.
                This reduction includes both removing the package manager
                and its unique dependencies as well as removing the package
                management data itself.
            </para>

            <para>
                To eliminate all the packaging requirements for an image,
                be sure that "package-management" is not part of your
                <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></ulink>
                statement for the image.
                When you remove this feature, you are removing the package
                manager as well as its dependencies from the root filesystem.
            </para>
        </section>

        <section id='look-for-other-ways-to-minimize-size'>
            <title>Look for Other Ways to Minimize Size</title>

            <para>
                Depending on your particular circumstances, other areas that you
                can trim likely exist.
                The key to finding these areas is through tools and methods
                described here combined with experimentation and iteration.
                Here are a couple of areas to experiment with:
                <itemizedlist>
                    <listitem><para><filename>glibc</filename>:
                        In general, follow this process:
                        <orderedlist>
                            <listitem><para>Remove <filename>glibc</filename>
                                features from
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></ulink>
                                that you think you do not need.</para></listitem>
                            <listitem><para>Build your distribution.
                                </para></listitem>
                            <listitem><para>If the build fails due to missing
                                symbols in a package, determine if you can
                                reconfigure the package to not need those
                                features.
                                For example, change the configuration to not
                                support wide character support as is done for
                                <filename>ncurses</filename>.
                                Or, if support for those characters is needed,
                                determine what <filename>glibc</filename>
                                features provide the support and restore the
                                configuration.
                                </para></listitem>
                            <listitem><para>Rebuild and repeat the process.
                                </para></listitem>
                        </orderedlist></para></listitem>
                    <listitem><para><filename>busybox</filename>:
                        For BusyBox, use a process similar as described for
                        <filename>glibc</filename>.
                        A difference is you will need to boot the resulting
                        system to see if you are able to do everything you
                        expect from the running system.
                        You need to be sure to integrate configuration fragments
                        into Busybox because BusyBox handles its own core
                        features and then allows you to add configuration
                        fragments on top.
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='iterate-on-the-process'>
            <title>Iterate on the Process</title>

            <para>
                If you have not reached your goals on system size, you need
                to iterate on the process.
                The process is the same.
                Use the tools and see just what is taking up 90% of the root
                filesystem and the kernel.
                Decide what you can eliminate without limiting your device
                beyond what you need.
            </para>

            <para>
                Depending on your system, a good place to look might be
                Busybox, which provides a stripped down
                version of Unix tools in a single, executable file.
                You might be able to drop virtual terminal services or perhaps
                ipv6.
            </para>
        </section>
    </section>

    <section id='building-images-for-more-than-one-machine'>
        <title>Building Images for More than One Machine</title>

        <para>
            A common scenario developers face is creating images for several
            different machines that use the same software environment.
            In this situation, it is tempting to set the
            tunings and optimization flags for each build specifically for
            the targeted hardware (i.e. "maxing out" the tunings).
            Doing so can considerably add to build times and package feed
            maintenance collectively for the machines.
            For example, selecting tunes that are extremely specific to a
            CPU core used in a system might enable some micro optimizations
            in GCC for that particular system but would otherwise not gain
            you much of a performance difference across the other systems
            as compared to using a more general tuning across all the builds
            (e.g. setting
            <ulink url='var-DEFAULTTUNE'><filename>DEFAULTTUNE</filename></ulink>
            specifically for each machine's build).
            Rather than "max out" each build's tunings, you can take steps that
            cause the OpenEmbedded build system to reuse software across the
            various machines where it makes sense.
        </para>
        <para>
            If build speed and package feed maintenance are considerations,
            you should consider the points in this section that can help you
            optimize your tunings to best consider build times and package
            feed maintenance.
            <itemizedlist>
                <listitem><para><emphasis>Share the Build Directory:</emphasis>
                    If at all possible, share the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>
                    across builds.
                    The Yocto Project supports switching between different
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
                    values in the same <filename>TMPDIR</filename>.
                    This practice is well supported and regularly used by
                    developers when building for multiple machines.
                    When you use the same <filename>TMPDIR</filename> for
                    multiple machine builds, the OpenEmbedded build system can
                    reuse the existing native and often cross-recipes for
                    multiple machines.
                    Thus, build time decreases.
                    <note>
                        If
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO'><filename>DISTRO</filename></ulink>
                        settings change or fundamental configuration settings
                        such as the filesystem layout, you need to work with
                        a clean <filename>TMPDIR</filename>.
                        Sharing <filename>TMPDIR</filename> under these
                        circumstances might work but since it is not
                        guaranteed, you should use a clean
                        <filename>TMPDIR</filename>.
                    </note>
                    </para></listitem>
                <listitem><para><emphasis>Enable the Appropriate Package Architecture:</emphasis>
                    By default, the OpenEmbedded build system enables three
                    levels of package architectures: "all", "tune" or "package",
                    and "machine".
                    Any given recipe usually selects one of these package
                    architectures (types) for its output.
                    Depending for what a given recipe creates packages, making
                    sure you enable the appropriate package architecture can
                    directly impact the build time.</para>
                    <para>A recipe that just generates scripts can enable
                    "all" architecture because there are no binaries to build.
                    To specifically enable "all" architecture, be sure your
                    recipe inherits the
                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-allarch'><filename>allarch</filename></ulink>
                    class.
                    This class is useful for "all" architectures because it
                    configures many variables so packages can be used across
                    multiple architectures.</para>
                    <para>If your recipe needs to generate packages that are
                    machine-specific or when one of the build or runtime
                    dependencies is already machine-architecture dependent,
                    which makes your recipe also machine-architecture dependent,
                    make sure your recipe enables the "machine" package
                    architecture through the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE_ARCH'><filename>MACHINE_ARCH</filename></ulink>
                    variable:
                    <literallayout class='monospaced'>
     PACKAGE_ARCH = "${MACHINE_ARCH}"
                    </literallayout>
                    When you do not specifically enable a package
                    architecture through the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></ulink>,
                    The OpenEmbedded build system defaults to the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-TUNE_PKGARCH'><filename>TUNE_PKGARCH</filename></ulink>
                    setting:
                    <literallayout class='monospaced'>
     PACKAGE_ARCH = "${TUNE_PKGARCH}"
                    </literallayout>
                    </para></listitem>
                <listitem><para><emphasis>Choose a Generic Tuning File if Possible:</emphasis>
                    Some tunes are more generic and can run on multiple targets
                    (e.g. an <filename>armv5</filename> set of packages could
                    run on <filename>armv6</filename> and
                    <filename>armv7</filename> processors in most cases).
                    Similarly, <filename>i486</filename> binaries could work
                    on <filename>i586</filename> and higher processors.
                    You should realize, however, that advances on newer
                    processor versions would not be used.</para>
                    <para>If you select the same tune for several different
                    machines, the OpenEmbedded build system reuses software
                    previously built, thus speeding up the overall build time.
                    Realize that even though a new sysroot for each machine is
                    generated, the software is not recompiled and only one
                    package feed exists.
                    </para></listitem>
                <listitem><para><emphasis>Manage Granular Level Packaging:</emphasis>
                    Sometimes cases exist where injecting another level
                    of package architecture beyond the three higher levels
                    noted earlier can be useful.
                    For example, consider the <filename>emgd</filename>
                    graphics stack in the
                    <filename>meta-intel</filename> layer.
                    In this layer, a subset of software exists that is
                    compiled against something different from the rest of the
                    generic packages.
                    You can examine the key code in the
                    <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi'>Source Repositories</ulink>
                    "daisy" branch in
                    <filename>classes/emgd-gl.bbclass</filename>.
                    For a specific set of packages, the code redefines
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></ulink>.
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_EXTRA_ARCHS'><filename>PACKAGE_EXTRA_ARCHS</filename></ulink>
                    is then appended with this extra tune name in
                    <filename>meta-intel-emgd.inc</filename>.
                    The result is that when searching for packages, the
                    build system uses a four-level search and the packages
                    in this new level are preferred as compared to the standard
                    tune.
                    The overall result is that the build system reuses most
                    software from the common tune except for specific cases
                    as needed.
                    </para></listitem>
                <listitem><para><emphasis>Use Tools to Debug Issues:</emphasis>
                    Sometimes you can run into situations where software is
                    being rebuilt when you think it should not be.
                    For example, the OpenEmbedded build system might not be
                    using shared state between machines when you think it
                    should be.
                    These types of situations are usually due to references
                    to machine-specific variables such as
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-SERIAL_CONSOLE'><filename>SERIAL_CONSOLE</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-XSERVER'><filename>XSERVER</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE_FEATURES'><filename>MACHINE_FEATURES</filename></ulink>,
                    and so forth in code that is supposed to only be
                    tune-specific or when the recipe depends
                    (<ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'><filename>RDEPENDS</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-RRECOMMENDS'><filename>RRECOMMENDS</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-RSUGGESTS'><filename>RSUGGESTS</filename></ulink>,
                    and so forth) on some other recipe that already has
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></ulink>
                    defined as "${MACHINE_ARCH}".
                    <note>
                        Patches to fix any issues identified are most welcome
                        as these issues occasionally do occur.
                    </note></para>
                    <para>For such cases, you can use some tools to help you
                    sort out the situation:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>sstate-diff-machines.sh</filename>:</emphasis>
                            You can find this tool in the
                            <filename>scripts</filename> directory of the
                            Source Repositories.
                            See the comments in the script for information on
                            how to use the tool.
                            </para></listitem>
                        <listitem><para><emphasis>BitBake's "-S printdiff" Option:</emphasis>
                            Using this option causes BitBake to try to
                            establish the closest signature match it can
                            (e.g. in the shared state cache) and then run
                            <filename>bitbake-diffsigs</filename> over the
                            matches to determine the stamps and delta where
                            these two stamp trees diverge.
                            </para></listitem>
                    </itemizedlist>
                    </para></listitem>
            </itemizedlist>
        </para>
    </section>

    <section id='working-with-packages'>
        <title>Working with Packages</title>

        <para>
            This section describes a few tasks that involve packages:
            <itemizedlist>
                <listitem><para>
                    <link linkend='excluding-packages-from-an-image'>Excluding packages from an image</link>
                    </para></listitem>
                <listitem><para>
                    <link linkend='incrementing-a-binary-package-version'>Incrementing a binary package version</link>
                    </para></listitem>
                <listitem><para>
                    <link linkend='handling-optional-module-packaging'>Handling optional module packaging</link>
                    </para></listitem>
                <listitem><para>
                    <link linkend='using-runtime-package-management'>Using Runtime Package Management</link>
                    </para></listitem>
                <listitem><para>
                    <link linkend='testing-packages-with-ptest'>Setting up and running package test (ptest)</link>
                    </para></listitem>
            </itemizedlist>
        </para>

        <section id='excluding-packages-from-an-image'>
            <title>Excluding Packages from an Image</title>

            <para>
                You might find it necessary to prevent specific packages
                from being installed into an image.
                If so, you can use several variables to direct the build
                system to essentially ignore installing recommended packages
                or to not install a package at all.
            </para>

            <para>
                The following list introduces variables you can use to
                prevent packages from being installed into your image.
                Each of these variables only works with IPK and RPM
                package types.
                Support for Debian packages does not exist.
                Also, you can use these variables from your
                <filename>local.conf</filename> file or attach them to a
                specific image recipe by using a recipe name override.
                For more detail on the variables, see the descriptions in the
                Yocto Project Reference Manual's glossary chapter.
                <itemizedlist>
                    <listitem><para><ulink url='&YOCTO_DOCS_REF_URL;#var-BAD_RECOMMENDATIONS'><filename>BAD_RECOMMENDATIONS</filename></ulink>:
                        Use this variable to specify "recommended-only"
                        packages that you do not want installed.
                        </para></listitem>
                    <listitem><para><ulink url='&YOCTO_DOCS_REF_URL;#var-NO_RECOMMENDATIONS'><filename>NO_RECOMMENDATIONS</filename></ulink>:
                        Use this variable to prevent all "recommended-only"
                        packages from being installed.
                        </para></listitem>
                    <listitem><para><ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_EXCLUDE'><filename>PACKAGE_EXCLUDE</filename></ulink>:
                        Use this variable to prevent specific packages from
                        being installed regardless of whether they are
                        "recommended-only" or not.
                        You need to realize that the build process could
                        fail with an error when you
                        prevent the installation of a package whose presence
                        is required by an installed package.
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='incrementing-a-binary-package-version'>
            <title>Incrementing a Package Version</title>

            <para>
                This section provides some background on how binary package
                versioning is accomplished and presents some of the services,
                variables, and terminology involved.
            </para>

            <para>
                In order to understand binary package versioning, you need
                to consider the following:
                <itemizedlist>
                    <listitem><para>
                        Binary Package:  The binary package that is eventually
                        built and installed into an image.
                        </para></listitem>
                    <listitem><para>
                        Binary Package Version:  The binary package version
                        is composed of two components - a version and a
                        revision.
                        <note>
                            Technically, a third component, the "epoch" (i.e.
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PE'><filename>PE</filename></ulink>)
                            is involved but this discussion for the most part
                            ignores <filename>PE</filename>.
                        </note>
                        The version and revision are taken from the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>
                        and
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>
                        variables, respectively.
                        </para></listitem>
                    <listitem><para>
                        <filename>PV</filename>:  The recipe version.
                        <filename>PV</filename> represents the version of the
                        software being packaged.
                        Do not confuse <filename>PV</filename> with the
                        binary package version.
                        </para></listitem>
                    <listitem><para>
                        <filename>PR</filename>:  The recipe revision.
                        </para></listitem>
                    <listitem><para>
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SRCPV'><filename>SRCPV</filename></ulink>:
                        The OpenEmbedded build system uses this string
                        to help define the value of <filename>PV</filename>
                        when the source code revision needs to be included
                        in it.
                        </para></listitem>
                    <listitem><para>
                        <ulink url='https://wiki.yoctoproject.org/wiki/PR_Service'>PR Service</ulink>:
                        A network-based service that helps automate keeping
                        package feeds compatible with existing package
                        manager applications such as RPM, APT, and OPKG.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                Whenever the binary package content changes, the binary package
                version must change.
                Changing the binary package version is accomplished by changing
                or "bumping" the <filename>PR</filename> and/or
                <filename>PV</filename> values.
                Increasing these values occurs one of two ways:
                <itemizedlist>
                    <listitem><para>Automatically using a Package Revision
                        Service (PR Service).
                        </para></listitem>
                    <listitem><para>Manually incrementing the
                        <filename>PR</filename> and/or
                        <filename>PV</filename> variables.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                Given a primary challenge of any build system and its users
                is how to maintain a package feed that is compatible with
                existing package manager applications such as RPM, APT, and
                OPKG, using an automated system is much preferred over a
                manual system.
                In either system, the main requirement is that binary package
                version numbering increases in a linear fashion and that a
                number of version components exist that support that linear
                progression.
                For information on how to ensure package revisioning remains
                linear, see the
                "<link linkend='automatically-incrementing-a-binary-package-revision-number'>Automatically Incrementing a Binary Package Revision Number</link>"
                section.
            </para>

            <para>
                The following three sections provide related information on the
                PR Service, the manual method for "bumping"
                <filename>PR</filename> and/or <filename>PV</filename>, and
                on how to ensure binary package revisioning remains linear.
            </para>

            <section id='working-with-a-pr-service'>
                <title>Working With a PR Service</title>

                <para>
                    As mentioned, attempting to maintain revision numbers in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink>
                    is error prone, inaccurate, and causes problems for people
                    submitting recipes.
                    Conversely, the PR Service automatically generates
                    increasing numbers, particularly the revision field,
                    which removes the human element.
                    <note>
                        For additional information on using a PR Service, you
                        can see the
                        <ulink url='&YOCTO_WIKI_URL;/wiki/PR_Service'>PR Service</ulink>
                        wiki page.
                    </note>
                </para>

                <para>
                    The Yocto Project uses variables in order of
                    decreasing priority to facilitate revision numbering (i.e.
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PE'><filename>PE</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>, and
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>
                    for epoch, version, and revision, respectively).
                    The values are highly dependent on the policies and
                    procedures of a given distribution and package feed.
                </para>

                <para>
                    Because the OpenEmbedded build system uses
                    "<ulink url='&YOCTO_DOCS_REF_URL;#checksums'>signatures</ulink>",
                    which are unique to a given build, the build system
                    knows when to rebuild packages.
                    All the inputs into a given task are represented by a
                    signature, which can trigger a rebuild when different.
                    Thus, the build system itself does not rely on the
                    <filename>PR</filename>, <filename>PV</filename>, and
                    <filename>PE</filename> numbers to trigger a rebuild.
                    The signatures, however, can be used to generate
                    these values.
                </para>

                <para>
                    The PR Service works with both
                    <filename>OEBasic</filename> and
                    <filename>OEBasicHash</filename> generators.
                    The value of <filename>PR</filename> bumps when the
                    checksum changes and the different generator mechanisms
                    change signatures under different circumstances.
                </para>

                <para>
                    As implemented, the build system includes values from
                    the PR Service into the <filename>PR</filename> field as
                    an addition using the form "<filename>.x</filename>" so
                    <filename>r0</filename> becomes <filename>r0.1</filename>,
                    <filename>r0.2</filename> and so forth.
                    This scheme allows existing <filename>PR</filename> values
                    to be used for whatever reasons, which include manual
                    <filename>PR</filename> bumps, should it be necessary.
                </para>

                <para>
                    By default, the PR Service is not enabled or running.
                    Thus, the packages generated are just "self consistent".
                    The build system adds and removes packages and
                    there are no guarantees about upgrade paths but images
                    will be consistent and correct with the latest changes.
                </para>

                <para>
                    The simplest form for a PR Service is for it to exist
                    for a single host development system that builds the
                    package feed (building system).
                    For this scenario, you can enable a local PR Service by
                    setting
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PRSERV_HOST'><filename>PRSERV_HOST</filename></ulink>
                    in your <filename>local.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>:
                    <literallayout class='monospaced'>
     PRSERV_HOST = "localhost:0"
                    </literallayout>
                    Once the service is started, packages will automatically
                    get increasing <filename>PR</filename> values and
                    BitBake takes care of starting and stopping the server.
                </para>

                <para>
                    If you have a more complex setup where multiple host
                    development systems work against a common, shared package
                    feed, you have a single PR Service running and it is
                    connected to each building system.
                    For this scenario, you need to start the PR Service using
                    the <filename>bitbake-prserv</filename> command:
                    <literallayout class='monospaced'>
     bitbake-prserv --host <replaceable>ip</replaceable> --port <replaceable>port</replaceable> --start
                    </literallayout>
                    In addition to hand-starting the service, you need to
                    update the <filename>local.conf</filename> file of each
                    building system as described earlier so each system
                    points to the server and port.
                </para>

                <para>
                    It is also recommended you use build history, which adds
                    some sanity checks to binary package versions, in
                    conjunction with the server that is running the PR Service.
                    To enable build history, add the following to each building
                    system's <filename>local.conf</filename> file:
                    <literallayout class='monospaced'>
     # It is recommended to activate "buildhistory" for testing the PR service
     INHERIT += "buildhistory"
     BUILDHISTORY_COMMIT = "1"
                    </literallayout>
                    For information on build history, see the
                    "<ulink url='&YOCTO_DOCS_REF_URL;#maintaining-build-output-quality'>Maintaining Build Output Quality</ulink>"
                    section in the Yocto Project Reference Manual.
                </para>

                <note>
                    <para>
                        The OpenEmbedded build system does not maintain
                        <filename>PR</filename> information as part of the
                        shared state (sstate) packages.
                        If you maintain an sstate feed, its expected that either
                        all your building systems that contribute to the sstate
                         feed use a shared PR Service, or you do not run a PR
                        Service on any of your building systems.
                        Having some systems use a PR Service while others do
                        not leads to obvious problems.
                    </para>

                    <para>
                        For more information on shared state, see the
                        "<ulink url='&YOCTO_DOCS_REF_URL;#shared-state-cache'>Shared State Cache</ulink>"
                        section in the Yocto Project Reference Manual.
                    </para>
                </note>
            </section>

            <section id='manually-bumping-pr'>
                <title>Manually Bumping PR</title>

                <para>
                    The alternative to setting up a PR Service is to manually
                    "bump" the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>
                    variable.
                </para>

                <para>
                    If a committed change results in changing the package
                    output, then the value of the PR variable needs to be
                    increased (or "bumped") as part of that commit.
                    For new recipes you should add the <filename>PR</filename>
                    variable and set its initial value equal to "r0", which is
                    the default.
                    Even though the default value is "r0", the practice of
                    adding it to a new recipe makes it harder to forget to bump
                    the variable when you make changes to the recipe in future.
                </para>

                <para>
                    If you are sharing a common <filename>.inc</filename> file
                    with multiple recipes, you can also use the
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-INC_PR'>INC_PR</ulink></filename>
                    variable to ensure that the recipes sharing the
                    <filename>.inc</filename> file are rebuilt when the
                    <filename>.inc</filename> file itself is changed.
                    The <filename>.inc</filename> file must set
                    <filename>INC_PR</filename> (initially to "r0"), and all
                    recipes referring to it should set <filename>PR</filename>
                    to "${INC_PR}.0" initially, incrementing the last number
                    when the recipe is changed.
                    If the <filename>.inc</filename> file is changed then its
                    <filename>INC_PR</filename> should be incremented.
                </para>

                <para>
                    When upgrading the version of a binary package, assuming the
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PV'>PV</ulink></filename>
                    changes, the <filename>PR</filename> variable should be
                    reset to "r0" (or "${INC_PR}.0" if you are using
                    <filename>INC_PR</filename>).
                </para>

                <para>
                    Usually, version increases occur only to binary packages.
                    However, if for some reason <filename>PV</filename> changes
                    but does not increase, you can increase the
                    <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PE'>PE</ulink></filename>
                    variable (Package Epoch).
                    The <filename>PE</filename> variable defaults to "0".
                </para>

                <para>
                    Binary package version numbering strives to follow the
                    <ulink url='http://www.debian.org/doc/debian-policy/ch-controlfields.html'>
                    Debian Version Field Policy Guidelines</ulink>.
                    These guidelines define how versions are compared and what
                    "increasing" a version means.
                </para>
            </section>

            <section id='automatically-incrementing-a-binary-package-revision-number'>
                <title>Automatically Incrementing a Package Version Number</title>

                <para>
                    When fetching a repository, BitBake uses the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-SRCREV'><filename>SRCREV</filename></ulink>
                    variable to determine the specific source code revision
                    from which to build.
                    You set the <filename>SRCREV</filename> variable to
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-AUTOREV'><filename>AUTOREV</filename></ulink>
                    to cause the OpenEmbedded build system to automatically use the
                    latest revision of the software:
                    <literallayout class='monospaced'>
     SRCREV = "${AUTOREV}"
                    </literallayout>
                </para>

                <para>
                    Furthermore, you need to reference <filename>SRCPV</filename>
                    in <filename>PV</filename> in order to automatically update
                    the version whenever the revision of the source code
                    changes.
                    Here is an example:
                    <literallayout class='monospaced'>
     PV = "1.0+git${SRCPV}"
                    </literallayout>
                    The OpenEmbedded build system substitutes
                    <filename>SRCPV</filename> with the following:
                    <literallayout class='monospaced'>
     AUTOINC+<replaceable>source_code_revision</replaceable>
                    </literallayout>
                    The build system replaces the <filename>AUTOINC</filename> with
                    a number.
                    The number used depends on the state of the PR Service:
                    <itemizedlist>
                        <listitem><para>
                            If PR Service is enabled, the build system increments
                            the number, which is similar to the behavior of
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>.
                            This behavior results in linearly increasing package
                            versions, which is desirable.
                            Here is an example:
                            <literallayout class='monospaced'>
     hello-world-git_0.0+git0+b6558dd387-r0.0_armv7a-neon.ipk
     hello-world-git_0.0+git1+dd2f5c3565-r0.0_armv7a-neon.ipk
                            </literallayout>
                            </para></listitem>
                        <listitem><para>
                            If PR Service is not enabled, the build system
                            replaces the <filename>AUTOINC</filename>
                            placeholder with zero (i.e. "0").
                            This results in changing the package version since
                            the source revision is included.
                            However, package versions are not increased linearly.
                            Here is an example:
                            <literallayout class='monospaced'>
     hello-world-git_0.0+git0+b6558dd387-r0.0_armv7a-neon.ipk
     hello-world-git_0.0+git0+dd2f5c3565-r0.0_armv7a-neon.ipk
                            </literallayout>
                            </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    In summary, the OpenEmbedded build system does not track the
                    history of binary package versions for this purpose.
                    <filename>AUTOINC</filename>, in this case, is comparable to
                    <filename>PR</filename>.
                    If PR server is not enabled, <filename>AUTOINC</filename>
                    in the package version is simply replaced by "0".
                    If PR server is enabled, the build system keeps track of the
                    package versions and bumps the number when the package
                    revision changes.
                </para>
            </section>
        </section>

        <section id='handling-optional-module-packaging'>
            <title>Handling Optional Module Packaging</title>

            <para>
                Many pieces of software split functionality into optional
                modules (or plug-ins) and the plug-ins that are built
                might depend on configuration options.
                To avoid having to duplicate the logic that determines what
                modules are available in your recipe or to avoid having
                to package each module by hand, the OpenEmbedded build system
                provides functionality to handle module packaging dynamically.
            </para>

            <para>
                To handle optional module packaging, you need to do two things:
                <itemizedlist>
                    <listitem><para>Ensure the module packaging is actually
                        done.</para></listitem>
                    <listitem><para>Ensure that any dependencies on optional
                        modules from other recipes are satisfied by your recipe.
                        </para></listitem>
                </itemizedlist>
            </para>

            <section id='making-sure-the-packaging-is-done'>
                <title>Making Sure the Packaging is Done</title>

                <para>
                    To ensure the module packaging actually gets done, you use
                    the <filename>do_split_packages</filename> function within
                    the <filename>populate_packages</filename> Python function
                    in your recipe.
                    The <filename>do_split_packages</filename> function
                    searches for a pattern of files or directories under a
                    specified path and creates a package for each one it finds
                    by appending to the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'><filename>PACKAGES</filename></ulink>
                    variable and setting the appropriate values for
                    <filename>FILES_packagename</filename>,
                    <filename>RDEPENDS_packagename</filename>,
                    <filename>DESCRIPTION_packagename</filename>, and so forth.
                    Here is an example from the <filename>lighttpd</filename>
                    recipe:
                    <literallayout class='monospaced'>
     python populate_packages_prepend () {
         lighttpd_libdir = d.expand('${libdir}')
         do_split_packages(d, lighttpd_libdir, '^mod_(.*)\.so$',
                          'lighttpd-module-%s', 'Lighttpd module for %s',
                           extra_depends='')
     }
                    </literallayout>
                    The previous example specifies a number of things in the
                    call to <filename>do_split_packages</filename>.
                    <itemizedlist>
                        <listitem><para>A directory within the files installed
                            by your recipe through <filename>do_install</filename>
                            in which to search.</para></listitem>
                        <listitem><para>A regular expression used to match module
                            files in that directory.
                            In the example, note the parentheses () that mark
                            the part of the expression from which the module
                            name should be derived.</para></listitem>
                        <listitem><para>A pattern to use for the package names.
                            </para></listitem>
                        <listitem><para>A description for each package.
                            </para></listitem>
                        <listitem><para>An empty string for
                            <filename>extra_depends</filename>, which disables
                            the default dependency on the main
                            <filename>lighttpd</filename> package.
                            Thus, if a file in <filename>${libdir}</filename>
                            called <filename>mod_alias.so</filename> is found,
                            a package called <filename>lighttpd-module-alias</filename>
                            is created for it and the
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-DESCRIPTION'><filename>DESCRIPTION</filename></ulink>
                            is set to "Lighttpd module for alias".</para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    Often, packaging modules is as simple as the previous
                    example.
                    However, more advanced options exist that you can use
                    within <filename>do_split_packages</filename> to modify its
                    behavior.
                    And, if you need to, you can add more logic by specifying
                    a hook function that is called for each package.
                    It is also perfectly acceptable to call
                    <filename>do_split_packages</filename> multiple times if
                    you have more than one set of modules to package.
                </para>

                <para>
                    For more examples that show how to use
                    <filename>do_split_packages</filename>, see the
                    <filename>connman.inc</filename> file in the
                    <filename>meta/recipes-connectivity/connman/</filename>
                    directory of the <filename>poky</filename>
                    <ulink url='&YOCTO_DOCS_REF_URL;#yocto-project-repositories'>source repository</ulink>.
                    You can also find examples in
                    <filename>meta/classes/kernel.bbclass</filename>.
                 </para>

                 <para>
                     Following is a reference that shows
                     <filename>do_split_packages</filename> mandatory and
                     optional arguments:
                     <literallayout class='monospaced'>
     Mandatory arguments

     root
        The path in which to search
     file_regex
        Regular expression to match searched files.
        Use parentheses () to mark the part of this
        expression that should be used to derive the
        module name (to be substituted where %s is
        used in other function arguments as noted below)
     output_pattern
        Pattern to use for the package names. Must
        include %s.
     description
        Description to set for each package. Must
        include %s.

     Optional arguments

     postinst
        Postinstall script to use for all packages
        (as a string)
     recursive
        True to perform a recursive search - default
        False
     hook
        A hook function to be called for every match.
        The function will be called with the following
        arguments (in the order listed):

        f
           Full path to the file/directory match
        pkg
           The package name
        file_regex
           As above
        output_pattern
           As above
        modulename
           The module name derived using file_regex

     extra_depends
        Extra runtime dependencies (RDEPENDS) to be
        set for all packages. The default value of None
        causes a dependency on the main package
        (${PN}) - if you do not want this, pass empty
        string '' for this parameter.
     aux_files_pattern
        Extra item(s) to be added to FILES for each
        package. Can be a single string item or a list
        of strings for multiple items. Must include %s.
     postrm
        postrm script to use for all packages (as a
        string)
     allow_dirs
        True to allow directories to be matched -
        default False
     prepend
        If True, prepend created packages to PACKAGES
        instead of the default False which appends them
     match_path
        match file_regex on the whole relative path to
        the root rather than just the file name
     aux_files_pattern_verbatim
        Extra item(s) to be added to FILES for each
        package, using the actual derived module name
        rather than converting it to something legal
        for a package name. Can be a single string item
        or a list of strings for multiple items. Must
        include %s.
     allow_links
        True to allow symlinks to be matched - default
        False
     summary
        Summary to set for each package. Must include %s;
        defaults to description if not set.
                     </literallayout>
                 </para>
            </section>

            <section id='satisfying-dependencies'>
                <title>Satisfying Dependencies</title>

                <para>
                    The second part for handling optional module packaging
                    is to ensure that any dependencies on optional modules
                    from other recipes are satisfied by your recipe.
                    You can be sure these dependencies are satisfied by
                    using the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES_DYNAMIC'><filename>PACKAGES_DYNAMIC</filename></ulink> variable.
                    Here is an example that continues with the
                    <filename>lighttpd</filename> recipe shown earlier:
                    <literallayout class='monospaced'>
     PACKAGES_DYNAMIC = "lighttpd-module-.*"
                    </literallayout>
                    The name specified in the regular expression can of
                    course be anything.
                    In this example, it is <filename>lighttpd-module-</filename>
                    and is specified as the prefix to ensure that any
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'><filename>RDEPENDS</filename></ulink>
                    and <ulink url='&YOCTO_DOCS_REF_URL;#var-RRECOMMENDS'><filename>RRECOMMENDS</filename></ulink>
                    on a package name starting with the prefix are satisfied
                    during build time.
                    If you are using <filename>do_split_packages</filename>
                    as described in the previous section, the value you put in
                    <filename>PACKAGES_DYNAMIC</filename> should correspond to
                    the name pattern specified in the call to
                    <filename>do_split_packages</filename>.
                </para>
            </section>
        </section>

        <section id='using-runtime-package-management'>
            <title>Using Runtime Package Management</title>

            <para>
                During a build, BitBake always transforms a recipe into one or
                more packages.
                For example, BitBake takes the <filename>bash</filename> recipe
                and currently produces the <filename>bash-dbg</filename>,
                <filename>bash-staticdev</filename>,
                <filename>bash-dev</filename>, <filename>bash-doc</filename>,
                <filename>bash-locale</filename>, and
                <filename>bash</filename> packages.
                Not all generated packages are included in an image.
            </para>

            <para>
                In several situations, you might need to update, add, remove,
                or query the packages on a target device at runtime
                (i.e. without having to generate a new image).
                Examples of such situations include:
                <itemizedlist>
                    <listitem><para>
                        You want to provide in-the-field updates to deployed
                        devices (e.g. security updates).
                        </para></listitem>
                    <listitem><para>
                        You want to have a fast turn-around development cycle
                        for one or more applications that run on your device.
                        </para></listitem>
                    <listitem><para>
                        You want to temporarily install the "debug" packages
                        of various applications on your device so that
                        debugging can be greatly improved by allowing
                        access to symbols and source debugging.
                        </para></listitem>
                    <listitem><para>
                        You want to deploy a more minimal package selection of
                        your device but allow in-the-field updates to add a
                        larger selection for customization.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                In all these situations, you have something similar to a more
                traditional Linux distribution in that in-field devices
                are able to receive pre-compiled packages from a server for
                installation or update.
                Being able to install these packages on a running,
                in-field device is what is termed "runtime package
                management".
            </para>

            <para>
                In order to use runtime package management, you
                need a host/server machine that serves up the pre-compiled
                packages plus the required metadata.
                You also need package manipulation tools on the target.
                The build machine is a likely candidate to act as the server.
                However, that machine does not necessarily have to be the
                package server.
                The build machine could push its artifacts to another machine
                that acts as the server (e.g. Internet-facing).
            </para>

            <para>
                A simple build that targets just one device produces
                more than one package database.
                In other words, the packages produced by a build are separated
                out into a couple of different package groupings based on
                criteria such as the target's CPU architecture, the target
                board, or the C library used on the target.
                For example, a build targeting the <filename>qemuarm</filename>
                device produces the following three package databases:
                <filename>all</filename>, <filename>armv5te</filename>, and
                <filename>qemuarm</filename>.
                If you wanted your <filename>qemuarm</filename> device to be
                aware of all the packages that were available to it,
                you would need to point it to each of these databases
                individually.
                In a similar way, a traditional Linux distribution usually is
                configured to be aware of a number of software repositories
                from which it retrieves packages.
            </para>

            <para>
                Using runtime package management is completely optional and
                not required for a successful build or deployment in any
                way.
                But if you want to make use of runtime package management,
                you need to do a couple things above and beyond the basics.
                The remainder of this section describes what you need to do.
            </para>

            <section id='runtime-package-management-build'>
                <title>Build Considerations</title>

                <para>
                    This section describes build considerations of which you
                    need to be aware in order to provide support for runtime
                    package management.
                </para>

                <para>
                    When BitBake generates packages, it needs to know
                    what format or formats to use.
                    In your configuration, you use the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></ulink>
                    variable to specify the format:
                    <orderedlist>
                        <listitem><para>
                            Open the <filename>local.conf</filename> file
                            inside your
                            <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
                            (e.g. <filename>~/poky/build/conf/local.conf</filename>).
                            </para></listitem>
                        <listitem><para>
                            Select the desired package format as follows:
                            <literallayout class='monospaced'>
     PACKAGE_CLASSES ?= “package_<replaceable>packageformat</replaceable></literallayout>
                            where <replaceable>packageformat</replaceable>
                            can be "ipk", "rpm", and "deb", which are the
                            supported package formats.
                            <note>
                                Because the Yocto Project supports three
                                different package formats, you can set the
                                variable with more than one argument.
                                However, the OpenEmbedded build system only
                                uses the first argument when creating an image
                                or Software Development Kit (SDK).
                            </note>
                            </para></listitem>
                    </orderedlist>
                </para>

                <para>
                    If you would like your image to start off with a basic
                    package database containing the packages in your current
                    build as well as to have the relevant tools available on the
                    target for runtime package management, you can include
                    "package-management" in the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></ulink>
                    variable.
                    Including "package-management" in this
                    configuration variable ensures that when the image
                    is assembled for your target, the image includes
                    the currently-known package databases as well as
                    the target-specific tools required for runtime
                    package management to be performed on the target.
                    However, this is not strictly necessary.
                    You could start your image off without any databases
                    but only include the required on-target package
                    tool(s).
                    As an example, you could include "opkg" in your
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></ulink>
                    variable if you are using the IPK package format.
                    You can then initialize your target's package database(s)
                    later once your image is up and running.
                </para>

                <para>
                    Whenever you perform any sort of build step that can
                    potentially generate a package or modify an existing
                    package, it is always a good idea to re-generate the
                    package index with:
                    <literallayout class='monospaced'>
    $ bitbake package-index
                    </literallayout>
                    Realize that it is not sufficient to simply do the
                    following:
                    <literallayout class='monospaced'>
    $ bitbake <replaceable>some-package</replaceable> package-index
                    </literallayout>
                    The reason for this restriction is because BitBake does not
                    properly schedule the <filename>package-index</filename>
                    target fully after any other target has completed.
                    Thus, be sure to run the package update step separately.
                </para>

                <para>
                    You can use the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_ARCHS'><filename>PACKAGE_FEED_ARCHS</filename></ulink>,
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_BASE_PATHS'><filename>PACKAGE_FEED_BASE_PATHS</filename></ulink>,
                    and
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_URIS'><filename>PACKAGE_FEED_URIS</filename></ulink>
                    variables to pre-configure target images to use a package
                    feed.
                    If you do not define these variables, then manual steps
                    as described in the subsequent sections are necessary to
                    configure the target.
                    You should set these variables before building the image
                    in order to produce a correctly configured image.
                </para>

                <para>
                    When your build is complete, your packages reside in the
                    <filename>${TMPDIR}/deploy/<replaceable>packageformat</replaceable></filename>
                    directory.
                    For example, if
                    <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink><filename>}</filename>
                    is <filename>tmp</filename> and your selected package type
                    is IPK, then your IPK packages are available in
                    <filename>tmp/deploy/ipk</filename>.
                </para>
            </section>

            <section id='runtime-package-management-server'>
                <title>Host or Server Machine Setup</title>

                <para>
                    Although other protocols are possible, a server using HTTP
                    typically serves packages.
                    If you want to use HTTP, then set up and configure a
                    web server such as Apache 2, lighttpd, or
                    SimpleHTTPServer on the machine serving the packages.
                </para>

                <para>
                    To keep things simple, this section describes how to set
                    up a SimpleHTTPServer web server to share package feeds
                    from the developer's machine.
                    Although this server might not be the best for a production
                    environment, the setup is simple and straight forward.
                    Should you want to use a different server more suited for
                    production (e.g. Apache 2, Lighttpd, or Nginx), take the
                    appropriate steps to do so.
                </para>

                <para>
                    From within the build directory where you have built an
                    image based on your packaging choice (i.e. the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></ulink>
                    setting), simply start the server.
                    The following example assumes a build directory of
                    <filename>~/poky/build/tmp/deploy/rpm</filename> and a
                    <filename>PACKAGE_CLASSES</filename> setting of
                    "package_rpm":
                    <literallayout class='monospaced'>
     $ cd ~/poky/build/tmp/deploy/rpm
     $ python -m SimpleHTTPServer
                    </literallayout>
                </para>
            </section>

            <section id='runtime-package-management-target'>
                <title>Target Setup</title>

                <para>
                    Setting up the target differs depending on the
                    package management system.
                    This section provides information for RPM, IPK, and DEB.
                </para>

                <section id='runtime-package-management-target-rpm'>
                    <title>Using RPM</title>

                    <para>
                        The <filename>dnf</filename> application performs
                        runtime package management of RPM packages.
                        You must perform an initial setup for
                        <filename>dnf</filename> on the target machine
                        if the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_ARCHS'><filename>PACKAGE_FEED_ARCHS</filename></ulink>,
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_BASE_PATHS'><filename>PACKAGE_FEED_BASE_PATHS</filename></ulink>,
                        and
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_URIS'><filename>PACKAGE_FEED_URIS</filename></ulink>
                        variables have not been set or the target image was
                        built before the variables were set.
                    </para>

                    <para>
                        As an example, assume the target is able to use the
                        following package databases:
                        <filename>all</filename>, <filename>i586</filename>,
                        and <filename>qemux86</filename> from a server named
                        <filename>my.server</filename>.
                        You must inform <filename>dnf</filename> of the
                        availability of these databases by creating a
                        <filename>/etc/yum.repos.d/oe-packages.repo</filename>
                        file with the following content:
                        <literallayout class='monospaced'>
     [oe-packages]
     baseurl=http://my.server/rpm/i586 http://my.server/rpm/qemux86 http://my.server/rpm/all
                        </literallayout>
                        From the target machine, fetch the repository:
                        <literallayout class='monospaced'>
     # dnf makecache
                        </literallayout>
                        After everything is set up, <filename>dnf</filename>
                        is able to find, install, and upgrade packages from
                        the specified repository.
                        <note>
                            See the
                            <ulink url='http://dnf.readthedocs.io/en/latest/'>DNF documentation</ulink>
                            for additional information.
                        </note>
                    </para>
                </section>

                <section id='runtime-package-management-target-ipk'>
                    <title>Using IPK</title>

                    <para>
                        The <filename>opkg</filename> application performs
                        runtime package management of IPK packages.
                        You must perform an initial setup for
                        <filename>opkg</filename> on the target machine
                        if the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_ARCHS'><filename>PACKAGE_FEED_ARCHS</filename></ulink>,
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_BASE_PATHS'><filename>PACKAGE_FEED_BASE_PATHS</filename></ulink>, and
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_URIS'><filename>PACKAGE_FEED_URIS</filename></ulink>
                        variables have not been set or the target image was
                        built before the variables were set.
                    </para>

                    <para>
                        The <filename>opkg</filename> application uses
                        configuration files to find available package
                        databases.
                        Thus, you need to create a configuration file inside
                        the <filename>/etc/opkg/</filename> direction, which
                        informs <filename>opkg</filename> of any repository
                        you want to use.
                    </para>

                    <para>
                        As an example, suppose you are serving packages from a
                        <filename>ipk/</filename> directory containing the
                        <filename>i586</filename>,
                        <filename>all</filename>, and
                        <filename>qemux86</filename> databases through an
                        HTTP server named <filename>my.server</filename>.
                        On the target, create a configuration file
                        (e.g. <filename>my_repo.conf</filename>) inside the
                        <filename>/etc/opkg/</filename> directory containing
                        the following:
                        <literallayout class='monospaced'>
     src/gz all http://my.server/ipk/all
     src/gz i586 http://my.server/ipk/i586
     src/gz qemux86 http://my.server/ipk/qemux86
                        </literallayout>
                        Next, instruct <filename>opkg</filename> to fetch
                        the repository information:
                        <literallayout class='monospaced'>
     # opkg update
                        </literallayout>
                        The <filename>opkg</filename> application is now able
                        to find, install, and upgrade packages from the
                        specified repository.
                    </para>
                </section>

                <section id='runtime-package-management-target-deb'>
                    <title>Using DEB</title>

                    <para>
                        The <filename>apt</filename> application performs
                        runtime package management of DEB packages.
                        This application uses a source list file to find
                        available package databases.
                        You must perform an initial setup for
                        <filename>apt</filename> on the target machine
                        if the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_ARCHS'><filename>PACKAGE_FEED_ARCHS</filename></ulink>,
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_BASE_PATHS'><filename>PACKAGE_FEED_BASE_PATHS</filename></ulink>, and
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_FEED_URIS'><filename>PACKAGE_FEED_URIS</filename></ulink>
                        variables have not been set or the target image was
                        built before the variables were set.
                    </para>

                    <para>
                        To inform <filename>apt</filename> of the repository
                        you want to use, you might create a list file (e.g.
                        <filename>my_repo.list</filename>) inside the
                        <filename>/etc/apt/sources.list.d/</filename>
                        directory.
                        As an example, suppose you are serving packages from a
                        <filename>deb/</filename> directory containing the
                        <filename>i586</filename>,
                        <filename>all</filename>, and
                        <filename>qemux86</filename> databases through an
                        HTTP server named <filename>my.server</filename>.
                        The list file should contain:
                        <literallayout class='monospaced'>
     deb http://my.server/deb/all ./
     deb http://my.server/deb/i586 ./
     deb http://my.server/deb/qemux86 ./
                        </literallayout>
                        Next, instruct the <filename>apt</filename>
                        application to fetch the repository information:
                        <literallayout class='monospaced'>
     # apt-get update
                        </literallayout>
                        After this step, <filename>apt</filename> is able
                        to find, install, and upgrade packages from the
                        specified repository.
                    </para>
                </section>
            </section>
        </section>

        <section id='generating-and-using-signed-packages'>
            <title>Generating and Using Signed Packages</title>
            <para>
                In order to add security to RPM packages used during a build,
                you can take steps to securely sign them.
                Once a signature is verified, the OpenEmbedded build system
                can use the package in the build.
                If security fails for a signed package, the build system
                aborts the build.
            </para>

            <para>
                This section describes how to sign RPM packages during a build
                and how to use signed package feeds (repositories) when
                doing a build.
            </para>

            <section id='signing-rpm-packages'>
                <title>Signing RPM Packages</title>

                <para>
                    To enable signing RPM packages, you must set up the
                    following configurations in either your
                    <filename>local.config</filename> or
                    <filename>distro.config</filename> file:
                    <literallayout class='monospaced'>
     # Inherit sign_rpm.bbclass to enable signing functionality
     INHERIT += " sign_rpm"
     # Define the GPG key that will be used for signing.
     RPM_GPG_NAME = "<replaceable>key_name</replaceable>"
     # Provide passphrase for the key
     RPM_GPG_PASSPHRASE = "<replaceable>passphrase</replaceable>"
                    </literallayout>
                    <note>
                        Be sure to supply appropriate values for both
                        <replaceable>key_name</replaceable> and
                        <replaceable>passphrase</replaceable>
                    </note>
                    Aside from the
                    <filename>RPM_GPG_NAME</filename> and
                    <filename>RPM_GPG_PASSPHRASE</filename> variables in the
                    previous example, two optional variables related to signing
                    exist:
                    <itemizedlist>
                        <listitem><para>
                            <emphasis><filename>GPG_BIN</filename>:</emphasis>
                            Specifies a <filename>gpg</filename> binary/wrapper
                            that is executed when the package is signed.
                            </para></listitem>
                        <listitem><para>
                            <emphasis><filename>GPG_PATH</filename>:</emphasis>
                            Specifies the <filename>gpg</filename> home
                            directory used when the package is signed.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>

            <section id='processing-package-feeds'>
                <title>Processing Package Feeds</title>

                <para>
                    In addition to being able to sign RPM packages, you can
                    also enable the OpenEmbedded build system to be able to
                    handle previously signed package feeds for IPK
                    packages.
                    <note>
                        The OpenEmbedded build system does not currently
                        support signed DPKG or RPM package feeds.
                    </note>
                    The steps you need to take to enable signed package feed
                    use are similar to the steps used to sign RPM packages.
                    You must define the following in your
                    <filename>local.config</filename> or
                    <filename>distro.config</filename> file:
                    <literallayout class='monospaced'>
     INHERIT += "sign_package_feed"
     PACKAGE_FEED_GPG_NAME = "<replaceable>key_name</replaceable>"
     PACKAGE_FEED_GPG_PASSPHRASE_FILE = "<replaceable>path_to_file_containing_passphrase</replaceable>"
                    </literallayout>
                    For signed package feeds, the passphrase must exist in a
                    separate file, which is pointed to by the
                    <filename>PACKAGE_FEED_GPG_PASSPHRASE_FILE</filename>
                    variable.
                    Regarding security, keeping a plain text passphrase out of
                    the configuration is more secure.
                </para>

                <para>
                    Aside from the
                    <filename>PACKAGE_FEED_GPG_NAME</filename> and
                    <filename>PACKAGE_FEED_GPG_PASSPHRASE_FILE</filename>
                    variables, three optional variables related to signed
                    package feeds exist:
                    <itemizedlist>
                        <listitem><para>
                            <emphasis><filename>GPG_BIN</filename>:</emphasis>
                            Specifies a <filename>gpg</filename> binary/wrapper
                            that is executed when the package is signed.
                            </para></listitem>
                        <listitem><para>
                            <emphasis><filename>GPG_PATH</filename>:</emphasis>
                            Specifies the <filename>gpg</filename> home
                            directory used when the package is signed.
                            </para></listitem>
                        <listitem><para>
                            <emphasis><filename>PACKAGE_FEED_GPG_SIGNATURE_TYPE</filename>:</emphasis>
                            Specifies the type of <filename>gpg</filename>
                            signature.
                            This variable applies only to RPM and IPK package
                            feeds.
                            Allowable values for the
                            <filename>PACKAGE_FEED_GPG_SIGNATURE_TYPE</filename>
                            are "ASC", which is the default and specifies ascii
                            armored, and "BIN", which specifies binary.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>
        </section>

        <section id='testing-packages-with-ptest'>
            <title>Testing Packages With ptest</title>

            <para>
                A Package Test (ptest) runs tests against packages built
                by the OpenEmbedded build system on the target machine.
                A ptest contains at least two items: the actual test, and
                a shell script (<filename>run-ptest</filename>) that starts
                the test.
                The shell script that starts the test must not contain
                the actual test - the script only starts the test.
                On the other hand, the test can be anything from a simple
                shell script that runs a binary and checks the output to
                an elaborate system of test binaries and data files.
            </para>

            <para>
                The test generates output in the format used by
                Automake:
                <literallayout class='monospaced'>
     <replaceable>result</replaceable>: <replaceable>testname</replaceable>
                </literallayout>
                where the result can be <filename>PASS</filename>,
                <filename>FAIL</filename>, or <filename>SKIP</filename>,
                and the testname can be any identifying string.
            </para>

            <para>
                For a list of Yocto Project recipes that are already
                enabled with ptest, see the
                <ulink url='https://wiki.yoctoproject.org/wiki/Ptest'>Ptest</ulink>
                wiki page.
                <note>
                    A recipe is "ptest-enabled" if it inherits the
                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-ptest'><filename>ptest</filename></ulink>
                    class.
                </note>
            </para>

            <section id='adding-ptest-to-your-build'>
                <title>Adding ptest to Your Build</title>

                <para>
                    To add package testing to your build, add the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></ulink>
                    and <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_IMAGE_FEATURES'><filename>EXTRA_IMAGE_FEATURES</filename></ulink>
                    variables to your <filename>local.conf</filename> file,
                    which is found in the
                    <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>:
                    <literallayout class='monospaced'>
     DISTRO_FEATURES_append = " ptest"
     EXTRA_IMAGE_FEATURES += "ptest-pkgs"
                    </literallayout>
                    Once your build is complete, the ptest files are installed
                    into the
                    <filename>/usr/lib/<replaceable>package</replaceable>/ptest</filename>
                    directory within the image, where
                    <filename><replaceable>package</replaceable></filename>
                    is the name of the package.
                </para>
            </section>

            <section id='running-ptest'>
                <title>Running ptest</title>

                <para>
                    The <filename>ptest-runner</filename> package installs a
                    shell script that loops through all installed ptest test
                    suites and runs them in sequence.
                    Consequently, you might want to add this package to
                    your image.
                </para>
            </section>

            <section id='getting-your-package-ready'>
                <title>Getting Your Package Ready</title>

                <para>
                    In order to enable a recipe to run installed ptests
                    on target hardware,
                    you need to prepare the recipes that build the packages
                    you want to test.
                    Here is what you have to do for each recipe:
                    <itemizedlist>
                        <listitem><para><emphasis>Be sure the recipe
                            inherits the
                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-ptest'><filename>ptest</filename></ulink>
                            class:</emphasis>
                            Include the following line in each recipe:
                            <literallayout class='monospaced'>
     inherit ptest
                            </literallayout>
                            </para></listitem>
                        <listitem><para><emphasis>Create <filename>run-ptest</filename>:</emphasis>
                            This script starts your test.
                            Locate the script where you will refer to it
                            using
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>.
                            Here is an example that starts a test for
                            <filename>dbus</filename>:
                            <literallayout class='monospaced'>
     #!/bin/sh
     cd test
     make -k runtest-TESTS
                            </literallayout>
                            </para></listitem>
                        <listitem><para><emphasis>Ensure dependencies are
                            met:</emphasis>
                            If the test adds build or runtime dependencies
                            that normally do not exist for the package
                            (such as requiring "make" to run the test suite),
                            use the
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
                            and
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'><filename>RDEPENDS</filename></ulink>
                            variables in your recipe in order for the package
                            to meet the dependencies.
                            Here is an example where the package has a runtime
                            dependency on "make":
                            <literallayout class='monospaced'>
     RDEPENDS_${PN}-ptest += "make"
                            </literallayout>
                            </para></listitem>
                        <listitem><para><emphasis>Add a function to build the
                            test suite:</emphasis>
                            Not many packages support cross-compilation of
                            their test suites.
                            Consequently, you usually need to add a
                            cross-compilation function to the package.
                            </para>

                            <para>Many packages based on Automake compile and
                            run the test suite by using a single command
                            such as <filename>make check</filename>.
                            However, the host <filename>make check</filename>
                            builds and runs on the same computer, while
                            cross-compiling requires that the package is built
                            on the host but executed for the target
                            architecture (though often, as in the case for
                            ptest, the execution occurs on the host).
                            The built version of Automake that ships with the
                            Yocto Project includes a patch that separates
                            building and execution.
                            Consequently, packages that use the unaltered,
                            patched version of <filename>make check</filename>
                            automatically cross-compiles.</para>
                            <para>Regardless, you still must add a
                            <filename>do_compile_ptest</filename> function to
                            build the test suite.
                            Add a function similar to the following to your
                            recipe:
                            <literallayout class='monospaced'>
     do_compile_ptest() {
        oe_runmake buildtest-TESTS
     }
                            </literallayout>
                            </para></listitem>
                       <listitem><para><emphasis>Ensure special configurations
                            are set:</emphasis>
                            If the package requires special configurations
                            prior to compiling the test code, you must
                            insert a <filename>do_configure_ptest</filename>
                            function into the recipe.
                            </para></listitem>
                       <listitem><para><emphasis>Install the test
                            suite:</emphasis>
                            The <filename>ptest</filename> class
                            automatically copies the file
                            <filename>run-ptest</filename> to the target and
                            then runs make <filename>install-ptest</filename>
                            to run the tests.
                            If this is not enough, you need to create a
                            <filename>do_install_ptest</filename> function and
                            make sure it gets called after the
                            "make install-ptest" completes.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>
        </section>
    </section>

    <section id='working-with-source-files'>
        <title>Working with Source Files</title>

        <para>
            The OpenEmbedded build system works with source files located
            through the
            <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
            variable.
            When you build something using BitBake, a big part of the operation
            is locating and downloading all the source tarballs.
            For images, downloading all the source for various packages can
            take a significant amount of time.
        </para>

        <para>
            This section presents information for working with source
            files that can lead to more efficient use of resources and
            time.
        </para>

        <section id='setting-up-effective-mirrors'>
            <title>Setting up Effective Mirrors</title>

            <para>
                As mentioned, a good deal that goes into a Yocto Project
                build is simply downloading all of the source tarballs.
                Maybe you have been working with another build system
                (OpenEmbedded or Angstrom) for which you have built up a
                sizable directory of source tarballs.
                Or, perhaps someone else has such a directory for which you
                have read access.
                If so, you can save time by adding statements to your
                configuration file so that the build process checks local
                directories first for existing tarballs before checking the
                Internet.
            </para>

            <para>
                Here is an efficient way to set it up in your
                <filename>local.conf</filename> file:
                <literallayout class='monospaced'>
     SOURCE_MIRROR_URL ?= "file:///home/you/your-download-dir/"
     INHERIT += "own-mirrors"
     BB_GENERATE_MIRROR_TARBALLS = "1"
     # BB_NO_NETWORK = "1"
                </literallayout>
            </para>

            <para>
                In the previous example, the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-BB_GENERATE_MIRROR_TARBALLS'><filename>BB_GENERATE_MIRROR_TARBALLS</filename></ulink>
                variable causes the OpenEmbedded build system to generate
                tarballs of the Git repositories and store them in the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'><filename>DL_DIR</filename></ulink>
                directory.
                Due to performance reasons, generating and storing these
                tarballs is not the build system's default behavior.
            </para>

            <para>
                You can also use the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PREMIRRORS'><filename>PREMIRRORS</filename></ulink>
                variable.
                For an example, see the variable's glossary entry in the
                Yocto Project Reference Manual.
            </para>
        </section>

        <section id='getting-source-files-and-suppressing-the-build'>
            <title>Getting Source Files and Suppressing the Build</title>

            <para>
                Another technique you can use to ready yourself for a
                successive string of build operations, is to pre-fetch
                all the source files without actually starting a build.
                This technique lets you work through any download issues
                and ultimately gathers all the source files into your
                download directory
                <ulink url='&YOCTO_DOCS_REF_URL;#structure-build-downloads'><filename>build/downloads</filename></ulink>,
                which is located with
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'><filename>DL_DIR</filename></ulink>.
            </para>

            <para>
                Use the following BitBake command form to fetch all the
                necessary sources without starting the build:
                <literallayout class='monospaced'>
     $ bitbake -c fetchall <replaceable>target</replaceable>
                </literallayout>
                This variation of the BitBake command guarantees that you
                have all the sources for that BitBake target should you
                disconnect from the Internet and want to do the build
                later offline.
            </para>
        </section>
    </section>

    <section id="building-software-from-an-external-source">
        <title>Building Software from an External Source</title>

        <para>
            By default, the OpenEmbedded build system uses the
            <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
            when building source code.
            The build process involves fetching the source files, unpacking
            them, and then patching them if necessary before the build takes
            place.
        </para>

        <para>
            Situations exist where you might want to build software from source
            files that are external to and thus outside of the
            OpenEmbedded build system.
            For example, suppose you have a project that includes a new BSP with
            a heavily customized kernel.
            And, you want to minimize exposing the build system to the
            development team so that they can focus on their project and
            maintain everyone's workflow as much as possible.
            In this case, you want a kernel source directory on the development
            machine where the development occurs.
            You want the recipe's
            <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
            variable to point to the external directory and use it as is, not
            copy it.
        </para>

        <para>
            To build from software that comes from an external source, all you
            need to do is inherit the
            <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-externalsrc'><filename>externalsrc</filename></ulink>
            class and then set the
            <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTERNALSRC'><filename>EXTERNALSRC</filename></ulink>
            variable to point to your external source code.
            Here are the statements to put in your
            <filename>local.conf</filename> file:
            <literallayout class='monospaced'>
     INHERIT += "externalsrc"
     EXTERNALSRC_pn-<replaceable>myrecipe</replaceable> = "<replaceable>path-to-your-source-tree</replaceable>"
            </literallayout>
        </para>

        <para>
            This next example shows how to accomplish the same thing by setting
            <filename>EXTERNALSRC</filename> in the recipe itself or in the
            recipe's append file:
            <literallayout class='monospaced'>
     EXTERNALSRC = "<replaceable>path</replaceable>"
     EXTERNALSRC_BUILD = "<replaceable>path</replaceable>"
            </literallayout>
            <note>
                In order for these settings to take effect, you must globally
                or locally inherit the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-externalsrc'><filename>externalsrc</filename></ulink>
                class.
            </note>
        </para>

        <para>
            By default, <filename>externalsrc.bbclass</filename> builds
            the source code in a directory separate from the external source
            directory as specified by
            <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTERNALSRC'><filename>EXTERNALSRC</filename></ulink>.
            If you need to have the source built in the same directory in
            which it resides, or some other nominated directory, you can set
            <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTERNALSRC_BUILD'><filename>EXTERNALSRC_BUILD</filename></ulink>
            to point to that directory:
            <literallayout class='monospaced'>
     EXTERNALSRC_BUILD_pn-<replaceable>myrecipe</replaceable> = "<replaceable>path-to-your-source-tree</replaceable>"
            </literallayout>
        </para>
    </section>

    <section id="selecting-an-initialization-manager">
        <title>Selecting an Initialization Manager</title>

        <para>
            By default, the Yocto Project uses SysVinit as the initialization
            manager.
            However, support also exists for systemd,
            which is a full replacement for init with
            parallel starting of services, reduced shell overhead and other
            features that are used by many distributions.
        </para>

        <para>
            If you want to use SysVinit, you do
            not have to do anything.
            But, if you want to use systemd, you must
            take some steps as described in the following sections.
        </para>

        <section id='using-systemd-exclusively'>
            <title>Using systemd Exclusively</title>

            <para>
                Set the these variables in your distribution configuration
                file as follows:
                <literallayout class='monospaced'>
     DISTRO_FEATURES_append = " systemd"
     VIRTUAL-RUNTIME_init_manager = "systemd"
                </literallayout>
                You can also prevent the SysVinit
                distribution feature from
                being automatically enabled as follows:
                <literallayout class='monospaced'>
     DISTRO_FEATURES_BACKFILL_CONSIDERED = "sysvinit"
                </literallayout>
                Doing so removes any redundant SysVinit scripts.
            </para>

            <para>
                To remove  initscripts from your image altogether,
                set this variable also:
                <literallayout class='monospaced'>
     VIRTUAL-RUNTIME_initscripts = ""
                </literallayout>
            </para>

            <para>
                For information on the backfill variable, see
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES_BACKFILL_CONSIDERED'><filename>DISTRO_FEATURES_BACKFILL_CONSIDERED</filename></ulink>.
            </para>
        </section>

        <section id='using-systemd-for-the-main-image-and-using-sysvinit-for-the-rescue-image'>
            <title>Using systemd for the Main Image and Using SysVinit for the Rescue Image</title>

            <para>
                Set these variables in your distribution configuration
                file as follows:
                <literallayout class='monospaced'>
     DISTRO_FEATURES_append = " systemd"
     VIRTUAL-RUNTIME_init_manager = "systemd"
                </literallayout>
                Doing so causes your main image to use the
                <filename>packagegroup-core-boot.bb</filename> recipe and
                systemd.
                The rescue/minimal image cannot use this package group.
                However, it can install SysVinit
                and the appropriate packages will have support for both
                systemd and SysVinit.
            </para>
        </section>
    </section>

    <section id="selecting-dev-manager">
        <title>Selecting a Device Manager</title>

        <para>
            The Yocto Project provides multiple ways to manage the device
            manager (<filename>/dev</filename>):
            <itemizedlist>
                <listitem><para><emphasis>Persistent and Pre-Populated<filename>/dev</filename>:</emphasis>
                    For this case, the <filename>/dev</filename> directory
                    is persistent and the required device nodes are created
                    during the build.
                    </para></listitem>
                <listitem><para><emphasis>Use <filename>devtmpfs</filename> with a Device Manager:</emphasis>
                    For this case, the <filename>/dev</filename> directory
                    is provided by the kernel as an in-memory file system and
                    is automatically populated by the kernel at runtime.
                    Additional configuration of device nodes is done in user
                    space by a device manager like
                    <filename>udev</filename> or
                    <filename>busybox-mdev</filename>.
                    </para></listitem>
            </itemizedlist>
        </para>

        <section id="static-dev-management">
            <title>Using Persistent and Pre-Populated<filename>/dev</filename></title>

            <para>
                To use the static method for device population, you need to
                set the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-USE_DEVFS'><filename>USE_DEVFS</filename></ulink>
                variable to "0" as follows:
                <literallayout class='monospaced'>
     USE_DEVFS = "0"
                </literallayout>
            </para>

            <para>
                The content of the resulting <filename>/dev</filename>
                directory is defined in a Device Table file.
                The
                <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_DEVICE_TABLES'><filename>IMAGE_DEVICE_TABLES</filename></ulink>
                variable defines the Device Table to use and should be set
                in the machine or distro configuration file.
                Alternatively, you can set this variable in your
                <filename>local.conf</filename> configuration file.
            </para>

            <para>
                If you do not define the
                <filename>IMAGE_DEVICE_TABLES</filename> variable, the default
                <filename>device_table-minimal.txt</filename> is used:
                <literallayout class='monospaced'>
     IMAGE_DEVICE_TABLES = "device_table-mymachine.txt"
                </literallayout>
            </para>

            <para>
                The population is handled by the <filename>makedevs</filename>
                utility during image creation:
            </para>
        </section>

        <section id="devtmpfs-dev-management">
            <title>Using <filename>devtmpfs</filename> and a Device Manager</title>

            <para>
                To use the dynamic method for device population, you need to
                use (or be sure to set) the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-USE_DEVFS'><filename>USE_DEVFS</filename></ulink>
                variable to "1", which is the default:
                <literallayout class='monospaced'>
     USE_DEVFS = "1"
                </literallayout>
                With this setting, the resulting <filename>/dev</filename>
                directory is populated by the kernel using
                <filename>devtmpfs</filename>.
                Make sure the corresponding kernel configuration variable
                <filename>CONFIG_DEVTMPFS</filename> is set when building
                you build a Linux kernel.
            </para>

            <para>
                All devices created by <filename>devtmpfs</filename> will be
                owned by <filename>root</filename> and have permissions
                <filename>0600</filename>.
            </para>

            <para>
                To have more control over the device nodes, you can use a
                device manager like <filename>udev</filename> or
                <filename>busybox-mdev</filename>.
                You choose the device manager by defining the
                <filename>VIRTUAL-RUNTIME_dev_manager</filename> variable
                in your machine or distro configuration file.
                Alternatively, you can set this variable in your
                <filename>local.conf</filename> configuration file:
                <literallayout class='monospaced'>
     VIRTUAL-RUNTIME_dev_manager = "udev"

     # Some alternative values
     # VIRTUAL-RUNTIME_dev_manager = "busybox-mdev"
     # VIRTUAL-RUNTIME_dev_manager = "systemd"
                </literallayout>
            </para>
        </section>
    </section>

    <section id="platdev-appdev-srcrev">
        <title>Using an External SCM</title>

        <para>
            If you're working on a recipe that pulls from an external Source
            Code Manager (SCM), it is possible to have the OpenEmbedded build
            system notice new recipe changes added to the SCM and then build
            the resulting packages that depend on the new recipes by using
            the latest versions.
            This only works for SCMs from which it is possible to get a
            sensible revision number for changes.
            Currently, you can do this with Apache Subversion (SVN), Git, and
            Bazaar (BZR) repositories.
        </para>

        <para>
            To enable this behavior, the
            <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>
            of the recipe needs to reference
            <ulink url='&YOCTO_DOCS_REF_URL;#var-SRCPV'><filename>SRCPV</filename></ulink>.
            Here is an example:
            <literallayout class='monospaced'>
     PV = "1.2.3+git${SRCPV}"
            </literallayout>
            Then, you can add the following to your
            <filename>local.conf</filename>:
            <literallayout class='monospaced'>
     SRCREV_pn-<replaceable>PN</replaceable> = "${AUTOREV}"
            </literallayout>
            <ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink>
            is the name of the recipe for which you want to enable automatic source
            revision updating.
        </para>

        <para>
            If you do not want to update your local configuration file, you can
            add the following directly to the recipe to finish enabling
            the feature:
            <literallayout class='monospaced'>
     SRCREV = "${AUTOREV}"
            </literallayout>
        </para>

        <para>
            The Yocto Project provides a distribution named
            <filename>poky-bleeding</filename>, whose configuration
            file contains the line:
            <literallayout class='monospaced'>
     require conf/distro/include/poky-floating-revisions.inc
            </literallayout>
            This line pulls in the listed include file that contains
            numerous lines of exactly that form:
            <literallayout class='monospaced'>
     #SRCREV_pn-opkg-native ?= "${AUTOREV}"
     #SRCREV_pn-opkg-sdk ?= "${AUTOREV}"
     #SRCREV_pn-opkg ?= "${AUTOREV}"
     #SRCREV_pn-opkg-utils-native ?= "${AUTOREV}"
     #SRCREV_pn-opkg-utils ?= "${AUTOREV}"
     SRCREV_pn-gconf-dbus ?= "${AUTOREV}"
     SRCREV_pn-matchbox-common ?= "${AUTOREV}"
     SRCREV_pn-matchbox-config-gtk ?= "${AUTOREV}"
     SRCREV_pn-matchbox-desktop ?= "${AUTOREV}"
     SRCREV_pn-matchbox-keyboard ?= "${AUTOREV}"
     SRCREV_pn-matchbox-panel-2 ?= "${AUTOREV}"
     SRCREV_pn-matchbox-themes-extra ?= "${AUTOREV}"
     SRCREV_pn-matchbox-terminal ?= "${AUTOREV}"
     SRCREV_pn-matchbox-wm ?= "${AUTOREV}"
     SRCREV_pn-settings-daemon ?= "${AUTOREV}"
     SRCREV_pn-screenshot ?= "${AUTOREV}"
          .
          .
          .
            </literallayout>
            These lines allow you to experiment with building a
            distribution that tracks the latest development source
            for numerous packages.
            <note><title>Caution</title>
                The <filename>poky-bleeding</filename> distribution
                is not tested on a regular basis.
                Keep this in mind if you use it.
            </note>
        </para>
    </section>

    <section id='creating-a-read-only-root-filesystem'>
        <title>Creating a Read-Only Root Filesystem</title>

        <para>
            Suppose, for security reasons, you need to disable
            your target device's root filesystem's write permissions
            (i.e. you need a read-only root filesystem).
            Or, perhaps you are running the device's operating system
            from a read-only storage device.
            For either case, you can customize your image for
            that behavior.
        </para>

        <note>
            Supporting a read-only root filesystem requires that the system and
            applications do not try to write to the root filesystem.
            You must configure all parts of the target system to write
            elsewhere, or to gracefully fail in the event of attempting to
            write to the root filesystem.
        </note>

        <section id='creating-the-root-filesystem'>
            <title>Creating the Root Filesystem</title>

            <para>
                To create the read-only root filesystem, simply add the
                "read-only-rootfs" feature to your image.
                Using either of the following statements in your
                image recipe or from within the
                <filename>local.conf</filename> file found in the
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
                causes the build system to create a read-only root filesystem:
                <literallayout class='monospaced'>
     IMAGE_FEATURES = "read-only-rootfs"
                </literallayout>
                or
                <literallayout class='monospaced'>
     EXTRA_IMAGE_FEATURES += "read-only-rootfs"
                </literallayout>
            </para>

            <para>
                For more information on how to use these variables, see the
                "<link linkend='usingpoky-extend-customimage-imagefeatures'>Customizing Images Using Custom <filename>IMAGE_FEATURES</filename> and <filename>EXTRA_IMAGE_FEATURES</filename></link>"
                section.
                For information on the variables, see
                <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></ulink>
                and <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_IMAGE_FEATURES'><filename>EXTRA_IMAGE_FEATURES</filename></ulink>.
            </para>
        </section>

        <section id='post-installation-scripts'>
            <title>Post-Installation Scripts</title>

            <para>
                It is very important that you make sure all
                post-Installation (<filename>pkg_postinst</filename>) scripts
                for packages that are installed into the image can be run
                at the time when the root filesystem is created during the
                build on the host system.
                These scripts cannot attempt to run during first-boot on the
                target device.
                With the "read-only-rootfs" feature enabled,
                the build system checks during root filesystem creation to make
                sure all post-installation scripts succeed.
                If any of these scripts still need to be run after the root
                filesystem is created, the build immediately fails.
                These build-time checks ensure that the build fails
                rather than the target device fails later during its
                initial boot operation.
            </para>

            <para>
                Most of the common post-installation scripts generated by the
                build system for the out-of-the-box Yocto Project are engineered
                so that they can run during root filesystem creation
                (e.g. post-installation scripts for caching fonts).
                However, if you create and add custom scripts, you need
                to be sure they can be run during this file system creation.
            </para>

            <para>
                Here are some common problems that prevent
                post-installation scripts from running during root filesystem
                creation:
                <itemizedlist>
                    <listitem><para>
                        <emphasis>Not using $D in front of absolute
                        paths:</emphasis>
                        The build system defines
                        <filename>$</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-D'><filename>D</filename></ulink>
                        when the root filesystem is created.
                        Furthermore, <filename>$D</filename> is blank when the
                        script is run on the target device.
                        This implies two purposes for <filename>$D</filename>:
                        ensuring paths are valid in both the host and target
                        environments, and checking to determine which
                        environment is being used as a method for taking
                        appropriate actions.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Attempting to run processes that are
                        specific to or dependent on the target
                        architecture:</emphasis>
                        You can work around these attempts by using native
                        tools, which run on the host system,
                        to accomplish the same tasks, or
                        by alternatively running the processes under QEMU,
                        which has the <filename>qemu_run_binary</filename>
                        function.
                        For more information, see the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-qemu'><filename>qemu</filename></ulink>
                        class.</para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='areas-with-write-access'>
            <title>Areas With Write Access</title>

            <para>
                With the "read-only-rootfs" feature enabled,
                any attempt by the target to write to the root filesystem at
                runtime fails.
                Consequently, you must make sure that you configure processes
                and applications that attempt these types of writes do so
                to directories with write access (e.g.
                <filename>/tmp</filename> or <filename>/var/run</filename>).
            </para>
        </section>
    </section>

    <section id="performing-automated-runtime-testing">
        <title>Performing Automated Runtime Testing</title>

        <para>
            The OpenEmbedded build system makes available a series of automated
            tests for images to verify runtime functionality.
            You can run these tests on either QEMU or actual target hardware.
            Tests are written in Python making use of the
            <filename>unittest</filename> module, and the majority of them
            run commands on the target system over SSH.
            This section describes how you set up the environment to use these
            tests, run available tests, and write and add your own tests.
        </para>

        <para>
            For information on the test and QA infrastructure available
            within the Yocto Project, see the
            "<ulink url='&YOCTO_DOCS_REF_URL;#testing-and-quality-assurance'>Testing and Quality Assurance</ulink>"
            section in the Yocto Project Reference Manual.
        </para>

        <section id='enabling-tests'>
            <title>Enabling Tests</title>

            <para>
                Depending on whether you are planning to run tests using
                QEMU or on the hardware, you have to take
                different steps to enable the tests.
                See the following subsections for information on how to
                enable both types of tests.
            </para>

            <section id='qemu-image-enabling-tests'>
                <title>Enabling Runtime Tests on QEMU</title>

                <para>
                    In order to run tests, you need to do the following:
                    <itemizedlist>
                        <listitem><para><emphasis>Set up to avoid interaction
                            with <filename>sudo</filename> for networking:</emphasis>
                            To accomplish this, you must do one of the
                            following:
                            <itemizedlist>
                                <listitem><para>Add
                                    <filename>NOPASSWD</filename> for your user
                                    in <filename>/etc/sudoers</filename> either for
                                    all commands or just for
                                    <filename>runqemu-ifup</filename>.
                                    You must provide the full path as that can
                                    change if you are using multiple clones of the
                                    source repository.
                                    <note>
                                        On some distributions, you also need to
                                        comment out "Defaults requiretty" in
                                        <filename>/etc/sudoers</filename>.
                                    </note></para></listitem>
                                <listitem><para>Manually configure a tap interface
                                    for your system.</para></listitem>
                                <listitem><para>Run as root the script in
                                    <filename>scripts/runqemu-gen-tapdevs</filename>,
                                    which should generate a list of tap devices.
                                    This is the option typically chosen for
                                    Autobuilder-type environments.
                                    </para></listitem>
                            </itemizedlist></para></listitem>
                        <listitem><para><emphasis>Set the
                            <filename>DISPLAY</filename> variable:</emphasis>
                            You need to set this variable so that you have an X
                            server available (e.g. start
                            <filename>vncserver</filename> for a headless machine).
                            </para></listitem>
                        <listitem><para><emphasis>Be sure your host's firewall
                            accepts incoming connections from
                            192.168.7.0/24:</emphasis>
                            Some of the tests (in particular DNF tests) start
                            an HTTP server on a random high number port,
                            which is used to serve files to the target.
                            The DNF module serves
                            <filename>${WORKDIR}/oe-rootfs-repo</filename>
                            so it can run DNF channel commands.
                            That means your host's firewall
                            must accept incoming connections from 192.168.7.0/24,
                            which is the default IP range used for tap devices
                            by <filename>runqemu</filename>.</para></listitem>
                        <listitem><para><emphasis>Be sure your host has the
                            correct packages installed:</emphasis>
                            Depending your host's distribution, you need
                            to have the following packages installed:
                            <itemizedlist>
                                <listitem><para>Ubuntu and Debian:
                                    <filename>sysstat</filename> and
                                    <filename>iproute2</filename>
                                    </para></listitem>
                                <listitem><para>OpenSUSE:
                                    <filename>sysstat</filename> and
                                    <filename>iproute2</filename>
                                    </para></listitem>
                                <listitem><para>Fedora:
                                    <filename>sysstat</filename> and
                                    <filename>iproute</filename>
                                    </para></listitem>
                                <listitem><para>CentOS:
                                    <filename>sysstat</filename> and
                                    <filename>iproute</filename>
                                    </para></listitem>
                            </itemizedlist>
                        </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    Once you start running the tests, the following happens:
                    <orderedlist>
                        <listitem><para>A copy of the root filesystem is written
                            to <filename>${WORKDIR}/testimage</filename>.
                            </para></listitem>
                        <listitem><para>The image is booted under QEMU using the
                            standard <filename>runqemu</filename> script.
                            </para></listitem>
                        <listitem><para>A default timeout of 500 seconds occurs
                            to allow for the boot process to reach the login prompt.
                            You can change the timeout period by setting
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-TEST_QEMUBOOT_TIMEOUT'><filename>TEST_QEMUBOOT_TIMEOUT</filename></ulink>
                            in the <filename>local.conf</filename> file.
                            </para></listitem>
                        <listitem><para>Once the boot process is reached and the
                            login prompt appears, the tests run.
                            The full boot log is written to
                            <filename>${WORKDIR}/testimage/qemu_boot_log</filename>.
                            </para></listitem>
                        <listitem><para>Each test module loads in the order found
                            in <filename>TEST_SUITES</filename>.
                            You can find the full output of the commands run over
                            SSH in
                            <filename>${WORKDIR}/testimgage/ssh_target_log</filename>.
                            </para></listitem>
                        <listitem><para>If no failures occur, the task running the
                            tests ends successfully.
                            You can find the output from the
                            <filename>unittest</filename> in the task log at
                            <filename>${WORKDIR}/temp/log.do_testimage</filename>.
                            </para></listitem>
                    </orderedlist>
                </para>
            </section>

            <section id='hardware-image-enabling-tests'>
                <title>Enabling Runtime Tests on Hardware</title>

                <para>
                    The OpenEmbedded build system can run tests on real
                    hardware, and for certain devices it can also deploy
                    the image to be tested onto the device beforehand.
                </para>

                <para>
                    For automated deployment, a "master image" is installed
                    onto the hardware once as part of setup.
                    Then, each time tests are to be run, the following
                    occurs:
                    <orderedlist>
                        <listitem><para>The master image is booted into and
                            used to write the image to be tested to
                            a second partition.
                            </para></listitem>
                        <listitem><para>The device is then rebooted using an
                            external script that you need to provide.
                            </para></listitem>
                        <listitem><para>The device boots into the image to be
                            tested.
                            </para></listitem>
                    </orderedlist>
                </para>

                <para>
                    When running tests (independent of whether the image
                    has been deployed automatically or not), the device is
                    expected to be connected to a network on a
                    pre-determined IP address.
                    You can either use static IP addresses written into
                    the image, or set the image to use DHCP and have your
                    DHCP server on the test network assign a known IP address
                    based on the MAC address of the device.
                </para>

                <para>
                    In order to run tests on hardware, you need to set
                    <filename>TEST_TARGET</filename> to an appropriate value.
                    For QEMU, you do not have to change anything, the default
                    value is "QemuTarget".
                    For running tests on hardware, the following options exist:
                    <itemizedlist>
                        <listitem><para><emphasis>"SimpleRemoteTarget":</emphasis>
                            Choose "SimpleRemoteTarget" if you are going to
                            run tests on a target system that is already
                            running the image to be tested and is available
                            on the network.
                            You can use "SimpleRemoteTarget" in conjunction
                            with either real hardware or an image running
                            within a separately started QEMU or any
                            other virtual machine manager.
                            </para></listitem>
                        <listitem><para><emphasis>"Systemd-bootTarget":</emphasis>
                            Choose "Systemd-bootTarget" if your hardware is
                            an EFI-based machine with
                            <filename>systemd-boot</filename> as bootloader and
                            <filename>core-image-testmaster</filename>
                            (or something similar) is installed.
                            Also, your hardware under test must be in a
                            DHCP-enabled network that gives it the same IP
                            address for each reboot.</para>
                            <para>If you choose "Systemd-bootTarget", there are
                            additional requirements and considerations.
                            See the
                            "<link linkend='selecting-systemd-boottarget'>Selecting Systemd-bootTarget</link>"
                            section, which follows, for more information.
                            </para></listitem>
                        <listitem><para><emphasis>"BeagleBoneTarget":</emphasis>
                            Choose "BeagleBoneTarget" if you are deploying
                            images and running tests on the BeagleBone
                            "Black" or original "White" hardware.
                            For information on how to use these tests, see the
                            comments at the top of the BeagleBoneTarget
                            <filename>meta-yocto-bsp/lib/oeqa/controllers/beaglebonetarget.py</filename>
                            file.
                            </para></listitem>
                        <listitem><para><emphasis>"EdgeRouterTarget":</emphasis>
                            Choose "EdgeRouterTarget" is you are deploying
                            images and running tests on the Ubiquiti Networks
                            EdgeRouter Lite.
                            For information on how to use these tests, see the
                            comments at the top of the EdgeRouterTarget
                            <filename>meta-yocto-bsp/lib/oeqa/controllers/edgeroutertarget.py</filename>
                            file.
                            </para></listitem>
                        <listitem><para><emphasis>"GrubTarget":</emphasis>
                            Choose the "supports deploying images and running
                            tests on any generic PC that boots using GRUB.
                            For information on how to use these tests, see the
                            comments at the top of the GrubTarget
                            <filename>meta-yocto-bsp/lib/oeqa/controllers/grubtarget.py</filename>
                            file.
                            </para></listitem>
                        <listitem><para><emphasis>"<replaceable>your-target</replaceable>":</emphasis>
                            Create your own custom target if you want to run
                            tests when you are deploying images and running
                            tests on a custom machine within your BSP layer.
                            To do this, you need to add a Python unit that
                            defines the target class under
                            <filename>lib/oeqa/controllers/</filename> within
                            your layer.
                            You must also provide an empty
                            <filename>__init__.py</filename>.
                            For examples, see files in
                            <filename>meta-yocto-bsp/lib/oeqa/controllers/</filename>.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>

            <section id='selecting-systemd-boottarget'>
                <title>Selecting Systemd-bootTarget</title>

                <para>
                    If you did not set <filename>TEST_TARGET</filename> to
                    "Systemd-bootTarget", then you do not need any information
                    in this section.
                    You can skip down to the
                    "<link linkend='qemu-image-running-tests'>Running Tests</link>"
                    section.
                </para>

                <para>
                    If you did set <filename>TEST_TARGET</filename> to
                    "Systemd-bootTarget", you also need to perform a one-time
                    setup of your master image by doing the following:
                    <orderedlist>
                        <listitem><para><emphasis>Set <filename>EFI_PROVIDER</filename>:</emphasis>
                            Be sure that <filename>EFI_PROVIDER</filename>
                            is as follows:
                            <literallayout class='monospaced'>
     EFI_PROVIDER = "systemd-boot"
                            </literallayout>
                            </para></listitem>
                        <listitem><para><emphasis>Build the master image:</emphasis>
                            Build the <filename>core-image-testmaster</filename>
                            image.
                            The <filename>core-image-testmaster</filename>
                            recipe is provided as an example for a
                            "master" image and you can customize the image
                            recipe as you would any other recipe.
                            </para>
                            <para>Here are the image recipe requirements:
                            <itemizedlist>
                                <listitem><para>Inherits
                                    <filename>core-image</filename>
                                    so that kernel modules are installed.
                                    </para></listitem>
                                <listitem><para>Installs normal linux utilities
                                    not busybox ones (e.g.
                                    <filename>bash</filename>,
                                    <filename>coreutils</filename>,
                                    <filename>tar</filename>,
                                    <filename>gzip</filename>, and
                                    <filename>kmod</filename>).
                                    </para></listitem>
                                <listitem><para>Uses a custom
                                    Initial RAM Disk (initramfs) image with a
                                    custom installer.
                                    A normal image that you can install usually
                                    creates a single rootfs partition.
                                    This image uses another installer that
                                    creates a specific partition layout.
                                    Not all Board Support Packages (BSPs)
                                    can use an installer.
                                    For such cases, you need to manually create
                                    the following partition layout on the
                                    target:
                                    <itemizedlist>
                                        <listitem><para>First partition mounted
                                            under <filename>/boot</filename>,
                                            labeled "boot".
                                            </para></listitem>
                                        <listitem><para>The main rootfs
                                            partition where this image gets
                                            installed, which is mounted under
                                            <filename>/</filename>.
                                            </para></listitem>
                                        <listitem><para>Another partition
                                            labeled "testrootfs" where test
                                            images get deployed.
                                            </para></listitem>
                                    </itemizedlist>
                                    </para></listitem>
                            </itemizedlist>
                            </para></listitem>
                        <listitem><para><emphasis>Install image:</emphasis>
                            Install the image that you just built on the target
                            system.
                            </para></listitem>
                    </orderedlist>
                </para>

                <para>
                    The final thing you need to do when setting
                    <filename>TEST_TARGET</filename> to "Systemd-bootTarget" is
                    to set up the test image:
                    <orderedlist>
                        <listitem><para><emphasis>Set up your <filename>local.conf</filename> file:</emphasis>
                            Make sure you have the following statements in
                            your <filename>local.conf</filename> file:
                            <literallayout class='monospaced'>
     IMAGE_FSTYPES += "tar.gz"
     INHERIT += "testimage"
     TEST_TARGET = "Systemd-bootTarget"
     TEST_TARGET_IP = "192.168.2.3"
                            </literallayout>
                            </para></listitem>
                        <listitem><para><emphasis>Build your test image:</emphasis>
                            Use BitBake to build the image:
                            <literallayout class='monospaced'>
     $ bitbake core-image-sato
                            </literallayout>
                            </para></listitem>
                    </orderedlist>
                </para>
            </section>

            <section id='power-control'>
                <title>Power Control</title>

                <para>
                    For most hardware targets other than SimpleRemoteTarget,
                    you can control power:
                    <itemizedlist>
                        <listitem><para>
                            You can use
                            <filename>TEST_POWERCONTROL_CMD</filename>
                            together with
                            <filename>TEST_POWERCONTROL_EXTRA_ARGS</filename>
                            as a command that runs on the host and does power
                            cycling.
                            The test code passes one argument to that command:
                            off, on or cycle (off then on).
                            Here is an example that could appear in your
                            <filename>local.conf</filename> file:
                            <literallayout class='monospaced'>
     TEST_POWERCONTROL_CMD = "powercontrol.exp test 10.11.12.1 nuc1"
                            </literallayout>
                            In this example, the expect script does the
                            following:
                            <literallayout class='monospaced'>
     ssh test@10.11.12.1 "pyctl nuc1 <replaceable>arg</replaceable>"
                            </literallayout>
                            It then runs a Python script that controls power
                            for a label called <filename>nuc1</filename>.
                            <note>
                                You need to customize
                                <filename>TEST_POWERCONTROL_CMD</filename>
                                and
                                <filename>TEST_POWERCONTROL_EXTRA_ARGS</filename>
                                for your own setup.
                                The one requirement is that it accepts
                                "on", "off", and "cycle" as the last argument.
                            </note>
                            </para></listitem>
                        <listitem><para>
                            When no command is defined, it connects to the
                            device over SSH and uses the classic reboot command
                            to reboot the device.
                            Classic reboot is fine as long as the machine
                            actually reboots (i.e. the SSH test has not
                            failed).
                            It is useful for scenarios where you have a simple
                            setup, typically with a single board, and where
                            some manual interaction is okay from time to time.
                            </para></listitem>
                    </itemizedlist>
                    If you have no hardware to automatically perform power
                    control but still wish to experiment with automated
                    hardware testing, you can use the dialog-power-control
                    script that shows a dialog prompting you to perform the
                    required power action.
                    This script requires either KDialog or Zenity to be
                    installed.
                    To use this script, set the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-TEST_POWERCONTROL_CMD'><filename>TEST_POWERCONTROL_CMD</filename></ulink>
                    variable as follows:
                    <literallayout class='monospaced'>
     TEST_POWERCONTROL_CMD = "${COREBASE}/scripts/contrib/dialog-power-control"
                    </literallayout>
                </para>
            </section>

            <section id='serial-console-connection'>
                <title>Serial Console Connection</title>

                <para>
                    For test target classes requiring a serial console
                    to interact with the bootloader (e.g. BeagleBoneTarget,
                    EdgeRouterTarget, and GrubTarget), you need to
                    specify a command to use to connect to the serial console
                    of the target machine by using the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-TEST_SERIALCONTROL_CMD'><filename>TEST_SERIALCONTROL_CMD</filename></ulink>
                    variable and optionally the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-TEST_SERIALCONTROL_EXTRA_ARGS'><filename>TEST_SERIALCONTROL_EXTRA_ARGS</filename></ulink>
                    variable.
                </para>

                <para>
                    These cases could be a serial terminal program if the
                    machine is connected to a local serial port, or a
                    <filename>telnet</filename> or
                    <filename>ssh</filename> command connecting to a remote
                    console server.
                    Regardless of the case, the command simply needs to
                    connect to the serial console and forward that connection
                    to standard input and output as any normal terminal
                    program does.
                    For example, to use the picocom terminal program on
                    serial device <filename>/dev/ttyUSB0</filename>
                    at 115200bps, you would set the variable as follows:
                    <literallayout class='monospaced'>
     TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200"
                    </literallayout>
                    For local devices where the serial port device disappears
                    when the device reboots, an additional "serdevtry" wrapper
                    script is provided.
                    To use this wrapper, simply prefix the terminal command
                    with
                    <filename>${COREBASE}/scripts/contrib/serdevtry</filename>:
                    <literallayout class='monospaced'>
     TEST_SERIALCONTROL_CMD = "${COREBASE}/scripts/contrib/serdevtry picocom -b
115200 /dev/ttyUSB0"
                    </literallayout>
                </para>
            </section>
        </section>

        <section id="qemu-image-running-tests">
            <title>Running Tests</title>

            <para>
                You can start the tests automatically or manually:
                <itemizedlist>
                    <listitem><para><emphasis>Automatically running tests:</emphasis>
                        To run the tests automatically after the
                        OpenEmbedded build system successfully creates an image,
                        first set the
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-TEST_IMAGE'><filename>TEST_IMAGE</filename></ulink>
                        variable to "1" in your <filename>local.conf</filename>
                        file in the
                        <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>:
                        <literallayout class='monospaced'>
     TEST_IMAGE = "1"
                        </literallayout>
                        Next, build your image.
                        If the image successfully builds, the tests will be
                        run:
                        <literallayout class='monospaced'>
     bitbake core-image-sato
                        </literallayout></para></listitem>
                    <listitem><para><emphasis>Manually running tests:</emphasis>
                        To manually run the tests, first globally inherit the
                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-testimage*'><filename>testimage</filename></ulink>
                        class by editing your <filename>local.conf</filename>
                        file:
                        <literallayout class='monospaced'>
    INHERIT += "testimage"
                        </literallayout>
                        Next, use BitBake to run the tests:
                        <literallayout class='monospaced'>
     bitbake -c testimage <replaceable>image</replaceable>
                        </literallayout></para></listitem>
                </itemizedlist>
            </para>

            <para>
                All test files reside in
                <filename>meta/lib/oeqa/runtime</filename> in the
                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
                A test name maps directly to a Python module.
                Each test module may contain a number of individual tests.
                Tests are usually grouped together by the area
                tested (e.g tests for systemd reside in
                <filename>meta/lib/oeqa/runtime/systemd.py</filename>).
            </para>

            <para>
                You can add tests to any layer provided you place them in the
                proper area and you extend
                <ulink url='&YOCTO_DOCS_REF_URL;#var-BBPATH'><filename>BBPATH</filename></ulink>
                in the <filename>local.conf</filename> file as normal.
                Be sure that tests reside in
                <filename><replaceable>layer</replaceable>/lib/oeqa/runtime</filename>.
                <note>
                    Be sure that module names do not collide with module names
                    used in the default set of test modules in
                    <filename>meta/lib/oeqa/runtime</filename>.
                </note>
            </para>

            <para>
                You can change the set of tests run by appending or overriding
                <ulink url='&YOCTO_DOCS_REF_URL;#var-TEST_SUITES'><filename>TEST_SUITES</filename></ulink>
                variable in <filename>local.conf</filename>.
                Each name in <filename>TEST_SUITES</filename> represents a
                required test for the image.
                Test modules named within <filename>TEST_SUITES</filename>
                cannot be skipped even if a test is not suitable for an image
                (e.g. running the RPM tests on an image without
                <filename>rpm</filename>).
                Appending "auto" to <filename>TEST_SUITES</filename> causes the
                build system to try to run all tests that are suitable for the
                image (i.e. each test module may elect to skip itself).
            </para>

            <para>
                The order you list tests in <filename>TEST_SUITES</filename>
                is important and influences test dependencies.
                Consequently, tests that depend on other tests should be added
                after the test on which they depend.
                For example, since the <filename>ssh</filename> test
                depends on the
                <filename>ping</filename> test, "ssh" needs to come after
                "ping" in the list.
                The test class provides no re-ordering or dependency handling.
                <note>
                    Each module can have multiple classes with multiple test
                    methods.
                    And, Python <filename>unittest</filename> rules apply.
                </note>
            </para>

            <para>
                Here are some things to keep in mind when running tests:
                <itemizedlist>
                    <listitem><para>The default tests for the image are defined
                        as:
                        <literallayout class='monospaced'>
     DEFAULT_TEST_SUITES_pn-<replaceable>image</replaceable> = "ping ssh df connman syslog xorg scp vnc date rpm dnf dmesg"
                        </literallayout></para></listitem>
                    <listitem><para>Add your own test to the list of the
                        by using the following:
                        <literallayout class='monospaced'>
     TEST_SUITES_append = " mytest"
                        </literallayout></para></listitem>
                    <listitem><para>Run a specific list of tests as follows:
                        <literallayout class='monospaced'>
     TEST_SUITES = "test1 test2 test3"
                        </literallayout>
                        Remember, order is important.
                        Be sure to place a test that is dependent on another test
                        later in the order.</para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id="exporting-tests">
            <title>Exporting Tests</title>

            <para>
                You can export tests so that they can run independently of
                the build system.
                Exporting tests is required if you want to be able to hand
                the test execution off to a scheduler.
                You can only export tests that are defined in
                <ulink url='&YOCTO_DOCS_REF_URL;#var-TEST_SUITES'><filename>TEST_SUITES</filename></ulink>.
            </para>

            <para>
                If your image is already built, make sure the following are set
                in your <filename>local.conf</filename> file:
                <literallayout class='monospaced'>
     INHERIT +="testexport"
     TEST_TARGET_IP = "<replaceable>IP-address-for-the-test-target</replaceable>"
     TEST_SERVER_IP = "<replaceable>IP-address-for-the-test-server</replaceable>"
                </literallayout>
                You can then export the tests with the following BitBake
                command form:
                <literallayout class='monospaced'>
     $ bitbake <replaceable>image</replaceable> -c testexport
                </literallayout>
                Exporting the tests places them in the
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
                in
                <filename>tmp/testexport/</filename><replaceable>image</replaceable>,
                which is controlled by the
                <filename>TEST_EXPORT_DIR</filename> variable.
            </para>

            <para>
                You can now run the tests outside of the build environment:
                <literallayout class='monospaced'>
     $ cd tmp/testexport/<replaceable>image</replaceable>
     $ ./runexported.py testdata.json
                </literallayout>
            </para>

            <para>
                Here is a complete example that shows IP addresses and uses
                the <filename>core-image-sato</filename> image:
                <literallayout class='monospaced'>
     INHERIT +="testexport"
     TEST_TARGET_IP = "192.168.7.2"
     TEST_SERVER_IP = "192.168.7.1"
                </literallayout>
                Use BitBake to export the tests:
                <literallayout class='monospaced'>
     $ bitbake core-image-sato -c testexport
                </literallayout>
                Run the tests outside of the build environment using the
                following:
                <literallayout class='monospaced'>
     $ cd tmp/testexport/core-image-sato
     $ ./runexported.py testdata.json
                </literallayout>
            </para>
        </section>

        <section id="qemu-image-writing-new-tests">
            <title>Writing New Tests</title>

            <para>
                As mentioned previously, all new test files need to be in the
                proper place for the build system to find them.
                New tests for additional functionality outside of the core
                should be added to the layer that adds the functionality, in
                <filename><replaceable>layer</replaceable>/lib/oeqa/runtime</filename>
                (as long as
                <ulink url='&YOCTO_DOCS_REF_URL;#var-BBPATH'><filename>BBPATH</filename></ulink>
                is extended in the layer's
                <filename>layer.conf</filename> file as normal).
                Just remember the following:
                <itemizedlist>
                    <listitem><para>Filenames need to map directly to test
                        (module) names.
                        </para></listitem>
                    <listitem><para>Do not use module names that
                        collide with existing core tests.
                        </para></listitem>
                    <listitem><para>Minimally, an empty
                        <filename>__init__.py</filename> file must exist
                        in the runtime directory.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                To create a new test, start by copying an existing module
                (e.g. <filename>syslog.py</filename> or
                <filename>gcc.py</filename> are good ones to use).
                Test modules can use code from
                <filename>meta/lib/oeqa/utils</filename>, which are helper
                classes.
            </para>

            <note>
                Structure shell commands such that you rely on them and they
                return a single code for success.
                Be aware that sometimes you will need to parse the output.
                See the <filename>df.py</filename> and
                <filename>date.py</filename> modules for examples.
            </note>

            <para>
                You will notice that all test classes inherit
                <filename>oeRuntimeTest</filename>, which is found in
                <filename>meta/lib/oetest.py</filename>.
                This base class offers some helper attributes, which are
                described in the following sections:
            </para>

            <section id='qemu-image-writing-tests-class-methods'>
                <title>Class Methods</title>

                <para>
                    Class methods are as follows:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>hasPackage(pkg)</filename>:</emphasis>
                            Returns "True" if <filename>pkg</filename> is in the
                            installed package list of the image, which is based
                            on the manifest file that is generated during the
                            <filename>do_rootfs</filename> task.
                            </para></listitem>
                        <listitem><para><emphasis><filename>hasFeature(feature)</filename>:</emphasis>
                            Returns "True" if the feature is in
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></ulink>
                            or
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></ulink>.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>

            <section id='qemu-image-writing-tests-class-attributes'>
                <title>Class Attributes</title>

                <para>
                    Class attributes are as follows:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>pscmd</filename>:</emphasis>
                            Equals "ps -ef" if <filename>procps</filename> is
                            installed in the image.
                            Otherwise, <filename>pscmd</filename> equals
                            "ps" (busybox).
                            </para></listitem>
                        <listitem><para><emphasis><filename>tc</filename>:</emphasis>
                            The called test context, which gives access to the
                            following attributes:
                            <itemizedlist>
                                <listitem><para><emphasis><filename>d</filename>:</emphasis>
                                    The BitBake datastore, which allows you to
                                    use stuff such as
                                    <filename>oeRuntimeTest.tc.d.getVar("VIRTUAL-RUNTIME_init_manager")</filename>.
                                    </para></listitem>
                                <listitem><para><emphasis><filename>testslist</filename> and <filename>testsrequired</filename>:</emphasis>
                                    Used internally.
                                    The tests do not need these.
                                    </para></listitem>
                                <listitem><para><emphasis><filename>filesdir</filename>:</emphasis>
                                    The absolute path to
                                    <filename>meta/lib/oeqa/runtime/files</filename>,
                                    which contains helper files for tests meant
                                    for copying on the target such as small
                                    files written in C for compilation.
                                    </para></listitem>
                                <listitem><para><emphasis><filename>target</filename>:</emphasis>
                                    The target controller object used to deploy
                                    and start an image on a particular target
                                    (e.g. QemuTarget, SimpleRemote, and
                                    Systemd-bootTarget).
                                    Tests usually use the following:
                                    <itemizedlist>
                                        <listitem><para><emphasis><filename>ip</filename>:</emphasis>
                                            The target's IP address.
                                            </para></listitem>
                                        <listitem><para><emphasis><filename>server_ip</filename>:</emphasis>
                                            The host's IP address, which is
                                            usually used by the DNF test
                                            suite.
                                            </para></listitem>
                                        <listitem><para><emphasis><filename>run(cmd, timeout=None)</filename>:</emphasis>
                                            The single, most used method.
                                            This command is a wrapper for:
                                            <filename>ssh root@host "cmd"</filename>.
                                            The command returns a tuple:
                                            (status, output), which are what
                                            their names imply - the return code
                                            of "cmd" and whatever output
                                            it produces.
                                            The optional timeout argument
                                            represents the number of seconds the
                                            test should wait for "cmd" to
                                            return.
                                            If the argument is "None", the
                                            test uses the default instance's
                                            timeout period, which is 300
                                            seconds.
                                            If the argument is "0", the test
                                            runs until the command returns.
                                            </para></listitem>
                                        <listitem><para><emphasis><filename>copy_to(localpath, remotepath)</filename>:</emphasis>
                                            <filename>scp localpath root@ip:remotepath</filename>.
                                            </para></listitem>
                                        <listitem><para><emphasis><filename>copy_from(remotepath, localpath)</filename>:</emphasis>
                                            <filename>scp root@host:remotepath localpath</filename>.
                                            </para></listitem>
                                    </itemizedlist></para></listitem>
                            </itemizedlist></para></listitem>
                    </itemizedlist>
                </para>
            </section>

            <section id='qemu-image-writing-tests-instance-attributes'>
                <title>Instance Attributes</title>

                <para>
                    A single instance attribute exists, which is
                    <filename>target</filename>.
                    The <filename>target</filename> instance attribute is
                    identical to the class attribute of the same name, which
                    is described in the previous section.
                    This attribute exists as both an instance and class
                    attribute so tests can use
                    <filename>self.target.run(cmd)</filename> in instance
                    methods instead of
                    <filename>oeRuntimeTest.tc.target.run(cmd)</filename>.
                </para>
            </section>
        </section>

        <section id='installing-packages-in-the-dut-without-the-package-manager'>
            <title>Installing Packages in the DUT Without the Package Manager</title>

            <para>
                When a test requires a package built by BitBake, it is possible
                to install that package.
                Installing the package does not require a package manager be
                installed in the device under test (DUT).
                It does, however, require an SSH connection and the target must
                be using the <filename>sshcontrol</filename> class.
                <note>
                    This method uses <filename>scp</filename> to copy files
                    from the host to the target, which causes permissions and
                    special attributes to be lost.
                </note>
            </para>

            <para>
                A JSON file is used to define the packages needed by a test.
                This file must be in the same path as the file used to define
                the tests.
                Furthermore, the filename must map directly to the test
                module name with a <filename>.json</filename> extension.
            </para>

            <para>
                The JSON file must include an object with the test name as
                keys of an object or an array.
                This object (or array of objects) uses the following data:
                <itemizedlist>
                    <listitem><para>"pkg" - A mandatory string that is the
                        name of the package to be installed.
                        </para></listitem>
                    <listitem><para>"rm" - An optional boolean, which defaults
                        to "false", that specifies to remove the package after
                        the test.
                        </para></listitem>
                    <listitem><para>"extract" - An optional boolean, which
                        defaults to "false", that specifies if the package must
                        be extracted from the package format.
                        When set to "true", the package is not automatically
                        installed into the DUT.
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                Following is an example JSON file that handles test "foo"
                installing package "bar" and test "foobar" installing
                packages "foo" and "bar".
                Once the test is complete, the packages are removed from the
                DUT.
                <literallayout class='monospaced'>
     {
         "foo": {
             "pkg": "bar"
         },
         "foobar": [
             {
                 "pkg": "foo",
                 "rm": true
             },
             {
                 "pkg": "bar",
                 "rm": true
             }
         ]
     }
                </literallayout>
            </para>
        </section>
    </section>

    <section id="platdev-gdb-remotedebug">
        <title>Debugging With the GNU Project Debugger (GDB) Remotely</title>

        <para>
            GDB allows you to examine running programs, which in turn helps you to understand and fix problems.
            It also allows you to perform post-mortem style analysis of program crashes.
            GDB is available as a package within the Yocto Project and is
            installed in SDK images by default.
            See the "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>" chapter
            in the Yocto Project Reference Manual for a description of these images.
            You can find information on GDB at <ulink url="http://sourceware.org/gdb/"/>.
        </para>

        <tip>
            For best results, install debug (<filename>-dbg</filename>) packages
            for the applications you are going to debug.
            Doing so makes extra debug symbols available that give you more
            meaningful output.
        </tip>

        <para>
            Sometimes, due to memory or disk space constraints, it is not possible
            to use GDB directly on the remote target to debug applications.
            These constraints arise because GDB needs to load the debugging information and the
            binaries of the process being debugged.
            Additionally, GDB needs to perform many computations to locate information such as function
            names, variable names and values, stack traces and so forth - even before starting the
            debugging process.
            These extra computations place more load on the target system and can alter the
            characteristics of the program being debugged.
        </para>

        <para>
            To help get past the previously mentioned constraints, you can use
            gdbserver, which runs on the remote target and does not load any
            debugging information from the debugged process.
            Instead, a GDB instance processes the debugging information that is run on a
            remote computer - the host GDB.
            The host GDB then sends control commands to gdbserver to make it stop or start the debugged
            program, as well as read or write memory regions of that debugged program.
            All the debugging information loaded and processed as well
            as all the heavy debugging is done by the host GDB.
            Offloading these processes gives the gdbserver running on the target a chance to remain
            small and fast.
        </para>

        <para>
            Because the host GDB is responsible for loading the debugging information and
            for doing the necessary processing to make actual debugging happen,
            you have to make sure the host can access the unstripped binaries complete
            with their debugging information and also be sure the target is compiled with no optimizations.
            The host GDB must also have local access to all the libraries used by the
            debugged program.
            Because gdbserver does not need any local debugging information, the binaries on
            the remote target can remain stripped.
            However, the binaries must also be compiled without optimization
            so they match the host's binaries.
        </para>

        <para>
            To remain consistent with GDB documentation and terminology, the binary being debugged
            on the remote target machine is referred to as the "inferior" binary.
            For documentation on GDB see the
            <ulink url="http://sourceware.org/gdb/documentation/">GDB site</ulink>.
        </para>

        <para>
            The following steps show you how to debug using the GNU project
            debugger.
            <orderedlist>
                <listitem><para>
                    <emphasis>Configure your build system to construct the
                    companion debug filesystem:</emphasis></para>

                    <para>In your <filename>local.conf</filename> file, set
                    the following:
                    <literallayout class='monospaced'>
     IMAGE_GEN_DEBUGFS = "1"
     IMAGE_FSTYPES_DEBUGFS = "tar.bz2"
                    </literallayout>
                    These options cause the OpenEmbedded build system
                    to generate a special companion filesystem fragment,
                    which contains the matching source and debug symbols to
                    your deployable filesystem.
                    The build system does this by looking at what is in the
                    deployed filesystem, and pulling the corresponding
                    <filename>-dbg</filename> packages.</para>

                    <para>The companion debug filesystem is not a complete
                    filesystem, but only contains the debug fragments.
                    This filesystem must be combined with the full filesystem
                    for debugging.
                    Subsequent steps in this procedure show how to combine
                    the partial filesystem with the full filesystem.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Configure the system to include gdbserver in
                    the target filesystem:</emphasis></para>

                    <para>Make the following addition in either your
                    <filename>local.conf</filename> file or in an image
                    recipe:
                    <literallayout class='monospaced'>
     IMAGE_INSTALL_append = “ gdbserver"
                    </literallayout>
                    The change makes sure the <filename>gdbserver</filename>
                    package is included.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Build the environment:</emphasis></para>

                    <para>Use the following command to construct the image and
                    the companion Debug Filesystem:
                    <literallayout class='monospaced'>
     $ bitbake <replaceable>image</replaceable>
                    </literallayout>
                    Build the cross GDB component and make it available
                    for debugging.
                    Build the SDK that matches the image.
                    Building the SDK is best for a production build
                    that can be used later for debugging, especially
                    during long term maintenance:
                    <literallayout class='monospaced'>
     $ bitbake -c populate_sdk <replaceable>image</replaceable>
                    </literallayout></para>

                    <para>Alternatively, you can build the minimal
                    toolchain components that match the target.
                    Doing so creates a smaller than typical SDK and only
                    contains a minimal set of components with which to
                    build simple test applications, as well as run the
                    debugger:
                    <literallayout class='monospaced'>
     $ bitbake meta-toolchain
                    </literallayout></para>

                    <para>A final method is to build Gdb itself within
                    the build system:
                    <literallayout class='monospaced'>
     $ bitbake gdb-cross-<replaceable>architecture</replaceable>
                    </literallayout>
                    Doing so produces a temporary copy of
                    <filename>cross-gdb</filename> you can use for
                    debugging during development.
                    While this is the quickest approach, the two previous
                    methods in this step are better when considering
                    long-term maintenance strategies.
                    <note>
                        If you run
                        <filename>bitbake gdb-cross</filename>, the
                        OpenEmbedded build system suggests the actual
                        image (e.g. <filename>gdb-cross-i586</filename>).
                        The suggestion is usually the actual name you want
                        to use.
                    </note>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Set up the</emphasis>&nbsp;<filename>debugfs</filename></para>

                    <para>Run the following commands to set up the
                    <filename>debugfs</filename>:
                    <literallayout class='monospaced'>
     $ mkdir debugfs
     $ cd debugfs
     $ tar xvfj <replaceable>build-dir</replaceable>/tmp-glibc/deploy/images/<replaceable>machine</replaceable>/<replaceable>image</replaceable>.rootfs.tar.bz2
     $ tar xvfj <replaceable>build-dir</replaceable>/tmp-glibc/deploy/images/<replaceable>machine</replaceable>/<replaceable>image</replaceable>-dbg.rootfs.tar.bz2
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Set up GDB</emphasis></para>

                    <para>Install the SDK (if you built one) and then
                    source the correct environment file.
                    Sourcing the environment file puts the SDK in your
                    <filename>PATH</filename> environment variable.</para>

                    <para>If you are using the build system, Gdb is
                    located in
                    <replaceable>build-dir</replaceable>/tmp/sysroots/<replaceable>host</replaceable>/usr/bin/<replaceable>architecture</replaceable>/<replaceable>architecture</replaceable>-gdb
                    </para></listitem>
                <listitem><para>
                    <emphasis>Boot the target:</emphasis></para>

                    <para>For information on how to run QEMU, see the
                    <ulink url='http://wiki.qemu.org/Documentation/GettingStartedDevelopers'>QEMU Documentation</ulink>.
                    <note>
                        Be sure to verify that your host can access the
                        target via TCP.
                    </note>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Debug a program:</emphasis></para>

                    <para>Debugging a program involves running gdbserver
                    on the target and then running Gdb on the host.
                    The example in this step debugs
                    <filename>gzip</filename>:
                    <literallayout class='monospaced'>
     root@qemux86:~# gdbserver localhost:1234 /bin/gzip —help
                    </literallayout>
                    For additional gdbserver options, see the
                    <ulink url='https://www.gnu.org/software/gdb/documentation/'>GDB Server Documentation</ulink>.
                    </para>

                    <para>After running gdbserver on the target, you need
                    to run Gdb on the host and configure it and connect to
                    the target.
                    Use these commands:
                    <literallayout class='monospaced'>
     $ cd <replaceable>directory-holding-the-debugfs-directory</replaceable>
     $ <replaceable>arch</replaceable>-gdb

     (gdb) set sysroot debugfs
     (gdb) set substitute-path /usr/src/debug debugfs/usr/src/debug
     (gdb) target remote <replaceable>IP-of-target</replaceable>:1234
                    </literallayout>
                    At this point, everything should automatically load
                    (i.e. matching binaries, symbols and headers).
                    <note>
                        The Gdb <filename>set</filename> commands in the
                        previous example can be placed into the users
                        <filename>~/.gdbinit</filename> file.
                        Upon starting, Gdb automatically runs whatever
                        commands are in that file.
                    </note>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Deploying without a full image
                    rebuild:</emphasis></para>

                    <para>In many cases, during development you want a
                    quick method to deploy a new binary to the target and
                    debug it, without waiting for a full image build.
                    </para>

                    <para>One approach to solving this situation is to
                    just build the component you want to debug.
                    Once you have built the component, copy the
                    executable directly to both the target and the
                    host <filename>debugfs</filename>.</para>

                    <para>If the binary is processed through the debug
                    splitting in OpenEmbedded, you should also
                    copy the debug items (i.e. <filename>.debug</filename>
                    contents and corresponding
                    <filename>/usr/src/debug</filename> files)
                    from the work directory.
                    Here is an example:
                    <literallayout class='monospaced'>
     $ bitbake bash
     $ bitbake -c devshell bash
     $ cd ..
     $ scp packages-split/bash/bin/bash <replaceable>target</replaceable>:/bin/bash
     $ cp -a packages-split/bash-dbg/* <replaceable>path</replaceable>/debugfs
                    </literallayout>
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

<!--
        <section id='platdev-gdb-remotedebug-setup'>
            <title>Set Up the Cross-Development Debugging Environment</title>

            <para>
                Before you can initiate a remote debugging session, you need
                to be sure you have set up the cross-development environment,
                toolchain, and sysroot.
                The <ulink url='&YOCTO_DOCS_SDK_URL;#sdk-intro'>Yocto Project Software Development Kit (SDK) Developer's Guide</ulink>
                describes this process.
            </para>
        </section>

        <section id="platdev-gdb-remotedebug-launch-gdbserver">
            <title>Launch gdbserver on the Target</title>

            <para>
                Make sure gdbserver is installed on the target.
                If it is not, install the package
                <filename>gdbserver</filename>, which needs the
                <filename>libthread-db1</filename> package.
            </para>

            <para>
                Here is an example, that when entered from the host,
                connects to the target and launches gdbserver in order to
                "debug" a binary named <filename>helloworld</filename>:
                <literallayout class='monospaced'>
     $ gdbserver localhost:2345 /usr/bin/helloworld
                </literallayout>
                gdbserver should now be listening on port 2345 for debugging
                commands coming from a remote GDB process that is running on
                the host computer.
                Communication between gdbserver and the host GDB are done
                using TCP.
                To use other communication protocols, please refer to the
                <ulink url='http://www.gnu.org/software/gdb/'>Gdbserver documentation</ulink>.
            </para>
        </section>

        <section id="platdev-gdb-remotedebug-launch-gdb">
            <title>Launch GDB on the Host Computer</title>

            <para>
                Running GDB on the host computer takes a number of stages, which
                this section describes.
            </para>

            <section id="platdev-gdb-remotedebug-launch-gdb-buildcross">
                <title>Build the Cross-GDB Package</title>
                <para>
                    A suitable GDB cross-binary is required that runs on your
                    host computer but also knows about the the ABI of the
                    remote target.
                    You can get this binary from the
                    <link linkend='cross-development-toolchain'>Cross-Development Toolchain</link>.
                    Here is an example where the toolchain has been installed
                    in the default directory
                    <filename>/opt/poky/&DISTRO;</filename>:
                    <literallayout class='monospaced'>
     /opt/poky/&DISTRO;/sysroots/i686-pokysdk-linux/usr/bin/armv7a-vfp-neon-poky-linux-gnueabi/arm-poky-linux-gnueabi-gdb
                    </literallayout>
                    where <filename>arm</filename> is the target architecture
                    and <filename>linux-gnueabi</filename> is the target ABI.
                </para>

                <para>
                    Alternatively, you can use BitBake to build the
                    <filename>gdb-cross</filename> binary.
                    Here is an example:
                    <literallayout class='monospaced'>
     $ bitbake gdb-cross
                    </literallayout>
                    Once the binary is built, you can find it here:
                    <literallayout class='monospaced'>
     tmp/sysroots/<replaceable>host-arch</replaceable>/usr/bin/<replaceable>target-platform</replaceable>/<replaceable>target-abi</replaceable>-gdb
                    </literallayout>
                </para>
            </section>

            <section id='create-the-gdb-initialization-file'>
                <title>Create the GDB Initialization File and Point to Your Root Filesystem</title>

                <para>
                    Aside from the GDB cross-binary, you also need a GDB
                    initialization file in the same top directory in which
                    your binary resides.
                    When you start GDB on your host development system, GDB
                    finds this initialization file and executes all the
                    commands within.
                    For information on the <filename>.gdbinit</filename>, see
                    "<ulink url='http://sourceware.org/gdb/onlinedocs/gdb/'>Debugging with GDB</ulink>",
                    which is maintained by
                    <ulink url='http://www.sourceware.org'>sourceware.org</ulink>.
                </para>

                <para>
                    You need to add a statement in the
                    <filename>~/.gdbinit</filename> file that points to your
                    root filesystem.
                    Here is an example that points to the root filesystem for
                    an ARM-based target device:
                    <literallayout class='monospaced'>
     set sysroot ~/sysroot_arm
                    </literallayout>
                </para>
            </section>

            <section id="platdev-gdb-remotedebug-launch-gdb-launchhost">
                <title>Launch the Host GDB</title>

                <para>
                    Before launching the host GDB, you need to be sure
                    you have sourced the cross-debugging environment script,
                    which if you installed the root filesystem in the default
                    location is at <filename>/opt/poky/&DISTRO;</filename>
                    and begins with the string "environment-setup".
                    For more information, see the
                    <ulink url='&YOCTO_DOCS_SDK_URL;#sdk-manual'>Yocto Project Software Development Kit (SDK) Developer's
                    Guide</ulink>.
                </para>

                <para>
                    Finally, switch to the directory where the binary resides
                    and run the <filename>cross-gdb</filename> binary.
                    Provide the binary file you are going to debug.
                    For example, the following command continues with the
                    example used in the previous section by loading
                    the <filename>helloworld</filename> binary as well as the
                    debugging information:
                    <literallayout class='monospaced'>
     $ arm-poky-linux-gnuabi-gdb helloworld
                    </literallayout>
                    The commands in your <filename>.gdbinit</filename> execute
                    and the GDB prompt appears.
                </para>
            </section>
        </section>

        <section id='platdev-gdb-connect-to-the-remote-gdb-server'>
            <title>Connect to the Remote GDB Server</title>

            <para>
                From the target, you need to connect to the remote GDB
                server that is running on the host.
                You need to specify the remote host and port.
                Here is the command continuing with the example:
                <literallayout class='monospaced'>
     target remote 192.168.7.2:2345
                </literallayout>
            </para>
        </section>

        <section id="platdev-gdb-remotedebug-launch-gdb-using">
            <title>Use the Debugger</title>

            <para>
                You can now proceed with debugging as normal - as if you were debugging
                on the local machine.
                For example, to instruct GDB to break in the "main" function and then
                continue with execution of the inferior binary use the following commands
                from within GDB:
                <literallayout class='monospaced'>
     (gdb) break main
     (gdb) continue
                </literallayout>
            </para>

            <para>
                For more information about using GDB, see the project's online documentation at
                <ulink url="http://sourceware.org/gdb/download/onlinedocs/"/>.
            </para>
        </section>
    </section>
-->

    <section id='debugging-with-the-gnu-project-debugger-gdb-on-the-target'>
        <title>Debugging with the GNU Project Debugger (GDB) on the Target</title>

        <para>
            The previous section addressed using GDB remotely for debugging
            purposes, which is the most usual case due to the inherent
            hardware limitations on many embedded devices.
            However, debugging in the target hardware itself is also possible
            with more powerful devices.
            This section describes what you need to do in order to support
            using GDB to debug on the target hardware.
        </para>

        <para>
            To support this kind of debugging, you need do the following:
            <itemizedlist>
                <listitem><para>
                    Ensure that GDB is on the target.
                    You can do this by adding "gdb" to
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></ulink>:
                    <literallayout class='monospaced'>
     IMAGE_INSTALL_append = " gdb"
                    </literallayout>
                    Alternatively, you can add "tools-debug" to
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></ulink>:
                    <literallayout class='monospaced'>
     IMAGE_FEATURES_append = " tools-debug"
                    </literallayout>
                    </para></listitem>
                <listitem><para>
                    Ensure that debug symbols are present.
                    You can make sure these symbols are present by installing
                    <filename>-dbg</filename>:
                    <literallayout class='monospaced'>
     IMAGE_INSTALL_append = " <replaceable>packagename</replaceable>-dbg"
                    </literallayout>
                    Alternatively, you can do the following to include all the
                    debug symbols:
                    <literallayout class='monospaced'>
     IMAGE_FEATURES_append = " dbg-pkgs"
                    </literallayout>
                    </para></listitem>
            </itemizedlist>
            <note>
                To improve the debug information accuracy, you can reduce the
                level of optimization used by the compiler.
                For example, when adding the following line to your
                <filename>local.conf</filename> file, you will reduce
                optimization from
                <ulink url='&YOCTO_DOCS_REF_URL;#var-FULL_OPTIMIZATION'><filename>FULL_OPTIMIZATION</filename></ulink>
                of "-O2" to
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DEBUG_OPTIMIZATION'><filename>DEBUG_OPTIMIZATION</filename></ulink>
                of "-O -fno-omit-frame-pointer":
                <literallayout class='monospaced'>
     DEBUG_BUILD = "1"
                </literallayout>
                Consider that this will reduce the application's performance
                and is recommended only for debugging purposes.
            </note>
        </para>
    </section>

    <section id='debugging-parallel-make-races'>
        <title>Debugging Parallel Make Races</title>

        <para>
            A parallel <filename>make</filename> race occurs when the build
            consists of several parts that are run simultaneously and
            a situation occurs when the output or result of one
            part is not ready for use with a different part of the build that
            depends on that output.
            Parallel make races are annoying and can sometimes be difficult
            to reproduce and fix.
            However, some simple tips and tricks exist that can help
            you debug and fix them.
            This section presents a real-world example of an error encountered
            on the Yocto Project autobuilder and the process used to fix it.
            <note>
                If you cannot properly fix a <filename>make</filename> race
                condition, you can work around it by clearing either the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink>
                or
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKEINST'><filename>PARALLEL_MAKEINST</filename></ulink>
                variables.
            </note>
        </para>

        <section id='the-failure'>
            <title>The Failure</title>

            <para>
                For this example, assume that you are building an image that
                depends on the "neard" package.
                And, during the build, BitBake runs into problems and
                creates the following output.
                <note>
                    This example log file has longer lines artificially
                    broken to make the listing easier to read.
                </note>
                If you examine the output or the log file, you see the
                failure during <filename>make</filename>:
                <literallayout class='monospaced'>
     | DEBUG: SITE files ['endian-little', 'bit-32', 'ix86-common', 'common-linux', 'common-glibc', 'i586-linux', 'common']
     | DEBUG: Executing shell function do_compile
     | NOTE: make -j 16
     | make --no-print-directory all-am
     | /bin/mkdir -p include/near
     | /bin/mkdir -p include/near
     | /bin/mkdir -p include/near
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/types.h include/near/types.h
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/log.h include/near/log.h
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/plugin.h include/near/plugin.h
     | /bin/mkdir -p include/near
     | /bin/mkdir -p include/near
     | /bin/mkdir -p include/near
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/tag.h include/near/tag.h
     | /bin/mkdir -p include/near
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/adapter.h include/near/adapter.h
     | /bin/mkdir -p include/near
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/ndef.h include/near/ndef.h
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/tlv.h include/near/tlv.h
     | /bin/mkdir -p include/near
     | /bin/mkdir -p include/near
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/setting.h include/near/setting.h
     | /bin/mkdir -p include/near
     | /bin/mkdir -p include/near
     | /bin/mkdir -p include/near
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/device.h include/near/device.h
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/nfc_copy.h include/near/nfc_copy.h
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/snep.h include/near/snep.h
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/version.h include/near/version.h
     | ln -s /home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/
       0.14-r0/neard-0.14/include/dbus.h include/near/dbus.h
     | ./src/genbuiltin nfctype1 nfctype2 nfctype3 nfctype4 p2p > src/builtin.h
     | i586-poky-linux-gcc  -m32 -march=i586 --sysroot=/home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/
       build/build/tmp/sysroots/qemux86 -DHAVE_CONFIG_H -I. -I./include -I./src -I./gdbus  -I/home/pokybuild/
       yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/sysroots/qemux86/usr/include/glib-2.0
       -I/home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/tmp/sysroots/qemux86/usr/
       lib/glib-2.0/include  -I/home/pokybuild/yocto-autobuilder/yocto-slave/nightly-x86/build/build/
       tmp/sysroots/qemux86/usr/include/dbus-1.0 -I/home/pokybuild/yocto-autobuilder/yocto-slave/
       nightly-x86/build/build/tmp/sysroots/qemux86/usr/lib/dbus-1.0/include  -I/home/pokybuild/yocto-autobuilder/
       yocto-slave/nightly-x86/build/build/tmp/sysroots/qemux86/usr/include/libnl3
       -DNEAR_PLUGIN_BUILTIN -DPLUGINDIR=\""/usr/lib/near/plugins"\"
       -DCONFIGDIR=\""/etc/neard\"" -O2 -pipe -g -feliminate-unused-debug-types -c
       -o tools/snep-send.o tools/snep-send.c
     | In file included from tools/snep-send.c:16:0:
     | tools/../src/near.h:41:23: fatal error: near/dbus.h: No such file or directory
     |  #include &lt;near/dbus.h&gt;
     |                        ^
     | compilation terminated.
     | make[1]: *** [tools/snep-send.o] Error 1
     | make[1]: *** Waiting for unfinished jobs....
     | make: *** [all] Error 2
     | ERROR: oe_runmake failed
                </literallayout>
            </para>
        </section>

        <section id='reproducing-the-error'>
            <title>Reproducing the Error</title>

            <para>
                Because race conditions are intermittent, they do not
                manifest themselves every time you do the build.
                In fact, most times the build will complete without problems
                even though the potential race condition exists.
                Thus, once the error surfaces, you need a way to reproduce it.
            </para>

            <para>
                In this example, compiling the "neard" package is causing the
                problem.
                So the first thing to do is build "neard" locally.
                Before you start the build, set the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink>
                variable in your <filename>local.conf</filename> file to
                a high number (e.g. "-j 20").
                Using a high value for <filename>PARALLEL_MAKE</filename>
                increases the chances of the race condition showing up:
                <literallayout class='monospaced'>
     $ bitbake neard
                </literallayout>
            </para>

            <para>
                Once the local build for "neard" completes, start a
                <filename>devshell</filename> build:
                <literallayout class='monospaced'>
     $ bitbake neard -c devshell
                </literallayout>
                For information on how to use a
                <filename>devshell</filename>, see the
                "<link linkend='platdev-appdev-devshell'>Using a Development Shell</link>"
                section.
            </para>

            <para>
                In the <filename>devshell</filename>, do the following:
                <literallayout class='monospaced'>
     $ make clean
     $ make tools/snep-send.o
                </literallayout>
                The <filename>devshell</filename> commands cause the failure
                to clearly be visible.
                In this case, a missing dependency exists for the "neard"
                Makefile target.
                Here is some abbreviated, sample output with the
                missing dependency clearly visible at the end:
                <literallayout class='monospaced'>
     i586-poky-linux-gcc  -m32 -march=i586 --sysroot=/home/scott-lenovo/......
        .
        .
        .
     tools/snep-send.c
     In file included from tools/snep-send.c:16:0:
     tools/../src/near.h:41:23: fatal error: near/dbus.h: No such file or directory
      #include &lt;near/dbus.h&gt;
                       ^
     compilation terminated.
     make: *** [tools/snep-send.o] Error 1
     $
                </literallayout>
            </para>
        </section>

        <section id='creating-a-patch-for-the-fix'>
            <title>Creating a Patch for the Fix</title>

            <para>
                Because there is a missing dependency for the Makefile
                target, you need to patch the
                <filename>Makefile.am</filename> file, which is generated
                from <filename>Makefile.in</filename>.
                You can use Quilt to create the patch:
                <literallayout class='monospaced'>
     $ quilt new parallelmake.patch
     Patch patches/parallelmake.patch is now on top
     $ quilt add Makefile.am
     File Makefile.am added to patch patches/parallelmake.patch
                </literallayout>
                For more information on using Quilt, see the
                "<link linkend='using-a-quilt-workflow'>Using Quilt in Your Workflow</link>"
                section.
            </para>

            <para>
                At this point you need to make the edits to
                <filename>Makefile.am</filename> to add the missing
                dependency.
                For our example, you have to add the following line
                to the file:
                <literallayout class='monospaced'>
     tools/snep-send.$(OBJEXT): include/near/dbus.h
                </literallayout>
            </para>

            <para>
                Once you have edited the file, use the
                <filename>refresh</filename> command to create the patch:
                <literallayout class='monospaced'>
     $ quilt refresh
     Refreshed patch patches/parallelmake.patch
                </literallayout>
                Once the patch file exists, you need to add it back to the
                originating recipe folder.
                Here is an example assuming a top-level
                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
                named <filename>poky</filename>:
                <literallayout class='monospaced'>
     $ cp patches/parallelmake.patch poky/meta/recipes-connectivity/neard/neard
                </literallayout>
                The final thing you need to do to implement the fix in the
                build is to update the "neard" recipe (i.e.
                <filename>neard-0.14.bb</filename>) so that the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                statement includes the patch file.
                The recipe file is in the folder above the patch.
                Here is what the edited <filename>SRC_URI</filename>
                statement would look like:
                <literallayout class='monospaced'>
     SRC_URI = "${KERNELORG_MIRROR}/linux/network/nfc/${BPN}-${PV}.tar.xz \
                file://neard.in \
                file://neard.service.in \
                file://parallelmake.patch \
               "
                </literallayout>
            </para>

            <para>
                With the patch complete and moved to the correct folder and
                the <filename>SRC_URI</filename> statement updated, you can
                exit the <filename>devshell</filename>:
                <literallayout class='monospaced'>
     $ exit
                </literallayout>
            </para>
        </section>

        <section id='testing-the-build'>
            <title>Testing the Build</title>

            <para>
                With everything in place, you can get back to trying the
                build again locally:
                <literallayout class='monospaced'>
     $ bitbake neard
                </literallayout>
                This build should succeed.
            </para>

            <para>
                Now you can open up a <filename>devshell</filename> again
                and repeat the clean and make operations as follows:
                <literallayout class='monospaced'>
     $ bitbake neard -c devshell
     $ make clean
     $ make tools/snep-send.o
                </literallayout>
                The build should work without issue.
            </para>

            <para>
                As with all solved problems, if they originated upstream, you
                need to submit the fix for the recipe in OE-Core and upstream
                so that the problem is taken care of at its source.
                See the
                "<link linkend='how-to-submit-a-change'>Submitting a Change to the Yocto Project</link>"
                section for more information.
            </para>
        </section>
    </section>

    <section id='maintaining-open-source-license-compliance-during-your-products-lifecycle'>
        <title>Maintaining Open Source License Compliance During Your Product's Lifecycle</title>

        <para>
            One of the concerns for a development organization using open source
            software is how to maintain compliance with various open source
            licensing during the lifecycle of the product.
            While this section does not provide legal advice or
            comprehensively cover all scenarios, it does
            present methods that you can use to
            assist you in meeting the compliance requirements during a software
            release.
        </para>

        <para>
            With hundreds of different open source licenses that the Yocto
            Project tracks, it is difficult to know the requirements of each
            and every license.
            However, the requirements of the major FLOSS licenses can begin
            to be covered by
            assuming that three main areas of concern exist:
            <itemizedlist>
                <listitem><para>Source code must be provided.</para></listitem>
                <listitem><para>License text for the software must be
                    provided.</para></listitem>
                <listitem><para>Compilation scripts and modifications to the
                    source code must be provided.
                    </para></listitem>
            </itemizedlist>
            There are other requirements beyond the scope of these
            three and the methods described in this section
            (e.g. the mechanism through which source code is distributed).
        </para>

        <para>
            As different organizations have different methods of complying with
            open source licensing, this section is not meant to imply that
            there is only one single way to meet your compliance obligations,
            but rather to describe one method of achieving compliance.
            The remainder of this section describes methods supported to meet the
            previously mentioned three requirements.
            Once you take steps to meet these requirements,
            and prior to releasing images, sources, and the build system,
            you should audit all artifacts to ensure completeness.
            <note>
                The Yocto Project generates a license manifest during
                image creation that is located
                in <filename>${DEPLOY_DIR}/licenses/<replaceable>image_name-datestamp</replaceable></filename>
                to assist with any audits.
            </note>
        </para>

        <section id='providing-the-source-code'>
            <title>Providing the Source Code</title>

            <para>
                Compliance activities should begin before you generate the
                final image.
                The first thing you should look at is the requirement that
                tops the list for most compliance groups - providing
                the source.
                The Yocto Project has a few ways of meeting this
                requirement.
            </para>

            <para>
                One of the easiest ways to meet this requirement is
                to provide the entire
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'><filename>DL_DIR</filename></ulink>
                used by the build.
                This method, however, has a few issues.
                The most obvious is the size of the directory since it includes
                all sources used in the build and not just the source used in
                the released image.
                It will include toolchain source, and other artifacts, which
                you would not generally release.
                However, the more serious issue for most companies is accidental
                release of proprietary software.
                The Yocto Project provides an
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-archiver'><filename>archiver</filename></ulink>
                class to help avoid some of these concerns.
            </para>

            <para>
                Before you employ <filename>DL_DIR</filename> or the
                <filename>archiver</filename> class, you need to decide how
                you choose to provide source.
                The source <filename>archiver</filename> class can generate
                tarballs and SRPMs and can create them with various levels of
                compliance in mind.
            </para>

            <para>
                One way of doing this (but certainly not the only way) is to
                release just the source as a tarball.
                You can do this by adding the following to the
                <filename>local.conf</filename> file found in the
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>:
                <literallayout class='monospaced'>
     INHERIT += "archiver"
     ARCHIVER_MODE[src] = "original"
                </literallayout>
                During the creation of your image, the source from all
                recipes that deploy packages to the image is placed within
                subdirectories of
                <filename>DEPLOY_DIR/sources</filename> based on the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-LICENSE'><filename>LICENSE</filename></ulink>
                for each recipe.
                Releasing the entire directory enables you to comply with
                requirements concerning providing the unmodified source.
                It is important to note that the size of the directory can
                get large.
            </para>

            <para>
                A way to help mitigate the size issue is to only release
                tarballs for licenses that require the release of
                source.
                Let us assume you are only concerned with GPL code as
                identified by running the following script:
                <literallayout class='monospaced'>
     # Script to archive a subset of packages matching specific license(s)
     # Source and license files are copied into sub folders of package folder
     # Must be run from build folder
     #!/bin/bash
     src_release_dir="source-release"
     mkdir -p $src_release_dir
     for a in tmp/deploy/sources/*; do
        for d in $a/*; do
           # Get package name from path
           p=`basename $d`
           p=${p%-*}
           p=${p%-*}
           # Only archive GPL packages (update *GPL* regex for your license check)
           numfiles=`ls tmp/deploy/licenses/$p/*GPL* 2> /dev/null | wc -l`
           if [ $numfiles -gt 1 ]; then
              echo Archiving $p
              mkdir -p $src_release_dir/$p/source
              cp $d/* $src_release_dir/$p/source 2> /dev/null
              mkdir -p $src_release_dir/$p/license
              cp tmp/deploy/licenses/$p/* $src_release_dir/$p/license 2> /dev/null
           fi
        done
     done                </literallayout>
                At this point, you could create a tarball from the
                <filename>gpl_source_release</filename> directory and
                provide that to the end user.
                This method would be a step toward achieving compliance
                with section 3a of GPLv2 and with section 6 of GPLv3.
            </para>
        </section>

        <section id='providing-license-text'>
            <title>Providing License Text</title>

            <para>
                One requirement that is often overlooked is inclusion
                of license text.
                This requirement also needs to be dealt with prior to
                generating the final image.
                Some licenses require the license text to accompany
                the binary.
                You can achieve this by adding the following to your
                <filename>local.conf</filename> file:
                <literallayout class='monospaced'>
     COPY_LIC_MANIFEST = "1"
     COPY_LIC_DIRS = "1"
     LICENSE_CREATE_PACKAGE = "1"
                </literallayout>
                Adding these statements to the configuration file ensures
                that the licenses collected during package generation
                are included on your image.
                <note>
                    <para>Setting all three variables to "1" results in the
                    image having two copies of the same license file.
                    One copy resides in
                    <filename>/usr/share/common-licenses</filename> and
                    the other resides in
                    <filename>/usr/share/license</filename>.</para>

                    <para>The reason for this behavior is because
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-COPY_LIC_DIRS'><filename>COPY_LIC_DIRS</filename></ulink>
                    and
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-COPY_LIC_MANIFEST'><filename>COPY_LIC_MANIFEST</filename></ulink>
                    add a copy of the license when the image is built but do
                    not offer a path for adding licenses for newly installed
                    packages to an image.
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-LICENSE_CREATE_PACKAGE'><filename>LICENSE_CREATE_PACKAGE</filename></ulink>
                    adds a separate package and an upgrade path for adding
                    licenses to an image.</para>
                </note>
            </para>

            <para>
                As the source <filename>archiver</filename> class has already
                archived the original
                unmodified source that contains the license files,
                you would have already met the requirements for inclusion
                of the license information with source as defined by the GPL
                and other open source licenses.
            </para>
        </section>

        <section id='providing-compilation-scripts-and-source-code-modifications'>
            <title>Providing Compilation Scripts and Source Code Modifications</title>

            <para>
                At this point, we have addressed all we need to
                prior to generating the image.
                The next two requirements are addressed during the final
                packaging of the release.
            </para>

            <para>
                By releasing the version of the OpenEmbedded build system
                and the layers used during the build, you will be providing both
                compilation scripts and the source code modifications in one
                step.
            </para>

            <para>
                If the deployment team has a
                <ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP layer</ulink>
                and a distro layer, and those those layers are used to patch,
                compile, package, or modify (in any way) any open source
                software included in your released images, you
                might be required to release those layers under section 3 of
                GPLv2 or section 1 of GPLv3.
                One way of doing that is with a clean
                checkout of the version of the Yocto Project and layers used
                during your build.
                Here is an example:
                <literallayout class='monospaced'>
     # We built using the &DISTRO_NAME_NO_CAP; branch of the poky repo
     $ git clone -b &DISTRO_NAME_NO_CAP; git://git.yoctoproject.org/poky
     $ cd poky
     # We built using the release_branch for our layers
     $ git clone -b release_branch git://git.mycompany.com/meta-my-bsp-layer
     $ git clone -b release_branch git://git.mycompany.com/meta-my-software-layer
     # clean up the .git repos
     $ find . -name ".git" -type d -exec rm -rf {} \;
                </literallayout>
                One thing a development organization might want to consider
                for end-user convenience is to modify
                <filename>meta-poky/conf/bblayers.conf.sample</filename> to
                ensure that when the end user utilizes the released build
                system to build an image, the development organization's
                layers are included in the <filename>bblayers.conf</filename>
                file automatically:
                <literallayout class='monospaced'>
     # LAYER_CONF_VERSION is increased each time build/conf/bblayers.conf
     # changes incompatibly
     LCONF_VERSION = "6"

     BBPATH = "${TOPDIR}"
     BBFILES ?= ""

     BBLAYERS ?= " \
       ##OEROOT##/meta \
       ##OEROOT##/meta-poky \
       ##OEROOT##/meta-yocto-bsp \
       ##OEROOT##/meta-mylayer \
       "
                </literallayout>
                Creating and providing an archive of the
                <ulink url='&YOCTO_DOCS_REF_URL;#metadata'>Metadata</ulink>
                layers (recipes, configuration files, and so forth)
                enables you to meet your
                requirements to include the scripts to control compilation
                as well as any modifications to the original source.
            </para>
        </section>
    </section>

    <section id='using-the-error-reporting-tool'>
        <title>Using the Error Reporting Tool</title>

        <para>
            The error reporting tool allows you to
            submit errors encountered during builds to a central database.
            Outside of the build environment, you can use a web interface to
            browse errors, view statistics, and query for errors.
            The tool works using a client-server system where the client
            portion is integrated with the installed Yocto Project
            <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
            (e.g. <filename>poky</filename>).
            The server receives the information collected and saves it in a
            database.
        </para>

        <para>
            A live instance of the error reporting server exists at
            <ulink url='http://errors.yoctoproject.org'></ulink>.
            This server exists so that when you want to get help with
            build failures, you can submit all of the information on the
            failure easily and then point to the URL in your bug report
            or send an email to the mailing list.
            <note>
                If you send error reports to this server, the reports become
                publicly visible.
            </note>
        </para>

        <section id='enabling-and-using-the-tool'>
            <title>Enabling and Using the Tool</title>

            <para>
                By default, the error reporting tool is disabled.
                You can enable it by inheriting the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-report-error'><filename>report-error</filename></ulink>
                class by adding the following statement to the end of
                your <filename>local.conf</filename> file in your
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
                <literallayout class='monospaced'>
     INHERIT += "report-error"
                </literallayout>
            </para>

            <para>
                By default, the error reporting feature stores information in
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LOG_DIR'><filename>LOG_DIR</filename></ulink><filename>}/error-report</filename>.
                However, you can specify a directory to use by adding the following
                to your <filename>local.conf</filename> file:
                <literallayout class='monospaced'>
     ERR_REPORT_DIR = "path"
                </literallayout>
                Enabling error reporting causes the build process to collect
                the errors and store them in a file as previously described.
                When the build system encounters an error, it includes a
                command as part of the console output.
                You can run the command to send the error file to the server.
                For example, the following command sends the errors to an
                upstream server:
                <literallayout class='monospaced'>
     $ send-error-report /home/brandusa/project/poky/build/tmp/log/error-report/error_report_201403141617.txt
                </literallayout>
                In the previous example, the errors are sent to a public
                database available at
                <ulink url='http://errors.yoctoproject.org'></ulink>, which is
                used by the entire community.
                If you specify a particular server, you can send the errors
                to a different database.
                Use the following command for more information on available
                options:
                <literallayout class='monospaced'>
     $ send-error-report --help
                </literallayout>
            </para>

            <para>
                When sending the error file, you are prompted to review the
                data being sent as well as to provide a name and optional
                email address.
                Once you satisfy these prompts, the command returns a link
                from the server that corresponds to your entry in the database.
                For example, here is a typical link:
                <literallayout class='monospaced'>
     http://errors.yoctoproject.org/Errors/Details/9522/
                </literallayout>
                Following the link takes you to a web interface where you can
                browse, query the errors, and view statistics.
             </para>
        </section>

        <section id='disabling-the-tool'>
            <title>Disabling the Tool</title>

            <para>
                To disable the error reporting feature, simply remove or comment
                out the following statement from the end of your
                <filename>local.conf</filename> file in your
                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
                <literallayout class='monospaced'>
     INHERIT += "report-error"
                </literallayout>
            </para>
        </section>

        <section id='setting-up-your-own-error-reporting-server'>
            <title>Setting Up Your Own Error Reporting Server</title>

            <para>
                If you want to set up your own error reporting server, you
                can obtain the code from the Git repository at
                <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi/error-report-web/'></ulink>.
                Instructions on how to set it up are in the README document.
            </para>
        </section>
     </section>
</chapter>

<!--
vim: expandtab tw=80 ts=4
-->