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
|
<!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='ref-classes'>
<title>Classes</title>
<para>
Class files are used to abstract common functionality and share it amongst
multiple recipe (<filename>.bb</filename>) files.
To use a class file, you simply make sure the recipe inherits the class.
In most cases, when a recipe inherits a class it is enough to enable its
features.
There are cases, however, where in the recipe you might need to set
variables or override some default behavior.
</para>
<para>
Any <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink> usually
found in a recipe can also be placed in a class file.
Class files are identified by the extension <filename>.bbclass</filename>
and are usually placed in a <filename>classes/</filename> directory beneath
the <filename>meta*/</filename> directory found in the
<ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
Class files can also be pointed to by
<link linkend='var-BUILDDIR'><filename>BUILDDIR</filename></link>
(e.g. <filename>build/</filename>) in the same way as
<filename>.conf</filename> files in the <filename>conf</filename> directory.
Class files are searched for in
<link linkend='var-BBPATH'><filename>BBPATH</filename></link>
using the same method by which <filename>.conf</filename> files are
searched.
</para>
<para>
This chapter discusses only the most useful and important classes.
Other classes do exist within the <filename>meta/classes</filename>
directory in the
<ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
You can reference the <filename>.bbclass</filename> files directly
for more information.
</para>
<section id='ref-classes-allarch'>
<title><filename>allarch.bbclass</filename></title>
<para>
The all architecture (<filename>allarch</filename>) class is inherited
by recipes that do not produce architecture-specific output.
The class disables functionality that is normally needed for recipes
that produce executable binaries (such as building the cross-compiler
and a C library as pre-requisites, and splitting out of debug symbols
during packaging).
</para>
<para>
By default, all recipes inherit the
<link linkend='ref-classes-base'><filename>base</filename></link> and
<link linkend='ref-classes-package'><filename>package</filename></link>
classes, which enable functionality
needed for recipes that produce executable output.
If your recipe, for example, only produces packages that contain
configuration files, media files, or scripts (e.g. Python and Perl),
then it should inherit the <filename>allarch</filename> class.
</para>
</section>
<section id='ref-classes-archiver'>
<title><filename>archive*.bbclass</filename></title>
<para>
The <filename>archive*</filename> set of classes support releasing
source code and other materials with the binaries.
This set of classes consists of the following:
<itemizedlist>
<listitem><filename>archive-original-sources.bbclass</filename></listitem>
<listitem><filename>archive-patched-sources.bbclass</filename></listitem>
<listitem><filename>archive-configured-sources.bbclass</filename></listitem>
<listitem><filename>archiver.bbclass</filename></listitem>
</itemizedlist>
</para>
<para>
For more details on the source archiver, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#maintaining-open-source-license-compliance-during-your-products-lifecycle'>Maintaining Open Source License Compliance During Your Product's Lifecycle</ulink>"
section in the Yocto Project Development Manual.
</para>
</section>
<section id='ref-classes-autotools'>
<title><filename>autotools.bbclass</filename></title>
<para>
The <filename>autotools</filename> class supports Autotooled
packages.
</para>
<para>
The <filename>autoconf</filename>, <filename>automake</filename>,
and <filename>libtool</filename> bring standardization.
This class defines a set of tasks (configure, compile etc.) that
work for all Autotooled packages.
It should usually be enough to define a few standard variables
and then simply <filename>inherit autotools</filename>.
This class can also work with software that emulates Autotools.
For more information, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#usingpoky-extend-addpkg-autotools'>Autotooled Package</ulink>"
section in the Yocto Project Development Manual.
</para>
<para>
It's useful to have some idea of how the tasks defined by this class work
and what they do behind the scenes.
<itemizedlist>
<listitem><para><filename>do_configure</filename> ‐ Regenerates the
configure script (using <filename>autoreconf</filename>) and then launches it
with a standard set of arguments used during cross-compilation.
You can pass additional parameters to <filename>configure</filename> through the
<filename><link linkend='var-EXTRA_OECONF'>EXTRA_OECONF</link></filename> variable.
</para></listitem>
<listitem><para><filename>do_compile</filename> ‐ Runs <filename>make</filename> with
arguments that specify the compiler and linker.
You can pass additional arguments through
the <filename><link linkend='var-EXTRA_OEMAKE'>EXTRA_OEMAKE</link></filename> variable.
</para></listitem>
<listitem><para><filename>do_install</filename> ‐ Runs <filename>make install</filename>
and passes in
<filename>${</filename><link linkend='var-D'><filename>D</filename></link><filename>}</filename>
as <filename>DESTDIR</filename>.
</para></listitem>
</itemizedlist>
</para>
</section>
<section id='ref-classes-base'>
<title><filename>base.bbclass</filename></title>
<para>
The <filename>base</filename> class is special in that every
<filename>.bb</filename> file automatically inherits the class.
This class contains definitions for standard basic
tasks such as fetching, unpacking, configuring (empty by default),
compiling (runs any <filename>Makefile</filename> present), installing
(empty by default) and packaging (empty by default).
These classes are often overridden or extended by other classes
such as the
<link linkend='ref-classes-autotools'><filename>autotools</filename></link>
class or the
<link linkend='ref-classes-package'><filename>package</filename></link>
class.
The class also contains some commonly used functions such as
<filename>oe_runmake</filename>.
</para>
</section>
<section id='ref-classes-bin-package'>
<title><filename>bin_package.bbclass</filename></title>
<para>
The <filename>bin_package</filename> class is a
helper class for recipes that extract the contents of a binary package
(e.g. an RPM) and install those contents rather than building the
binary from source.
The binary package is extracted and new packages in the configured
output package format are created.
<note>
For RPMs and other packages that do not contain a subdirectory,
you should specify a "subdir" parameter.
Here is an example where <filename>${BP}</filename> matches the
subdirectory expected by the default value of
<link linkend='var-S'><filename>S</filename></link>:
<literallayout class='monospaced'>
SRC_URI = "http://example.com/downloads/somepackage.rpm;subdir=${BP}"
</literallayout>
</note>
</para>
</section>
<section id='ref-classes-binconfig'>
<title><filename>binconfig.bbclass</filename></title>
<para>
The <filename>binconfig</filename> class helps to correct paths in
shell scripts.
</para>
<para>
Before <filename>pkg-config</filename> had become widespread, libraries
shipped shell scripts to give information about the libraries and
include paths needed to build software (usually named
<filename>LIBNAME-config</filename>).
This class assists any recipe using such scripts.
</para>
<para>
During staging, the OpenEmbedded build system installs such scripts
into the <filename>sysroots/</filename> directory.
Inheriting this class results in all paths in these scripts being
changed to point into the <filename>sysroots/</filename> directory so
that all builds that use the script use the correct directories
for the cross compiling layout.
See the
<link linkend='var-BINCONFIG_GLOB'><filename>BINCONFIG_GLOB</filename></link>
variable for more information.
</para>
</section>
<section id='ref-classes-blacklist'>
<title><filename>blacklist.bbclass</filename></title>
<para>
The <filename>blacklist</filename> class prevents
the OpenEmbedded build system from building specific recipes
(blacklists them).
To use this class, inherit the class globally and set
<link linkend='var-PNBLACKLIST'><filename>PNBLACKLIST</filename></link>
for each recipe you wish to blacklist.
Specify the <link linkend='var-PN'><filename>PN</filename></link>
value as a variable flag (varflag) and provide a reason, which is
reported, if the package is requested to be built as the value.
For example, if you want to blacklist a recipe called "exoticware",
you add the following to your <filename>local.conf</filename>
or distribution configuration:
<literallayout class='monospaced'>
INHERIT += "blacklist"
PNBLACKLIST[exoticware] = "Not supported by our organization."
</literallayout>
</para>
</section>
<section id='ref-classes-boot-directdisk'>
<title><filename>boot-directdisk.bbclass</filename></title>
<para>
The <filename>boot-directdisk</filename> class
creates an image that can be placed directly onto a hard disk using
<filename>dd</filename> and then booted.
The image uses SYSLINUX.
</para>
<para>
The end result is a 512 boot sector populated with a
Master Boot Record (MBR) and partition table followed by an MSDOS
FAT16 partition containing SYSLINUX and a Linux kernel completed by
the <filename>ext2</filename> and <filename>ext3</filename>
root filesystems.
</para>
</section>
<section id='ref-classes-bootimg'>
<title><filename>bootimg.bbclass</filename></title>
<para>
The <filename>bootimg</filename> class creates a bootable
image using SYSLINUX, your kernel and an optional initial RAM disk
(<filename>initrd</filename>).
</para>
<para>
When you use this class, two things happen:
<itemizedlist>
<listitem><para>
A <filename>.hddimg</filename> file is created.
This file which is an MSDOS filesystem that contains SYSLINUX,
a kernel, an <filename>initrd</filename>, and a root filesystem
image.
All three of these can be written to hard drives directly and
also booted on a USB flash disks using <filename>dd</filename>.
</para></listitem>
<listitem><para>
A CD <filename>.iso</filename> image is created.
When this file is booted, the <filename>initrd</filename>
boots and processes the label selected in SYSLINUX.
Actions based on the label are then performed (e.g. installing
to a hard drive).</para></listitem>
</itemizedlist>
</para>
<para>
The <filename>bootimg</filename> class supports the
<link linkend='var-INITRD'><filename>INITRD</filename></link>,
<link linkend='var-NOISO'><filename>NOISO</filename></link>,
<link linkend='var-NOHDD'><filename>NOHDD</filename></link>, and
<link linkend='var-ROOTFS'><filename>ROOTFS</filename></link>
variables.
</para>
</section>
<section id='ref-classes-bugzilla'>
<title><filename>bugzilla.bbclass</filename></title>
<para>
The <filename>bugzilla</filename> class, if enabled in
your instance of Bugzilla, automatically files bug reports to that
enabled instance in response to build failures.
This class uses Bugzilla's XML-RPC interface.
</para>
</section>
<section id='ref-classes-buildhistory'>
<title><filename>buildhistory.bbclass</filename></title>
<para>
The <filename>buildhistory</filename> class records a
history of build output metadata, which can be used to detect possible
regressions as well as used for analysis of the build output.
For more information on using Build History, see the
"<link linkend='maintaining-build-output-quality'>Maintaining Build Output Quality</link>"
section.
</para>
</section>
<section id='ref-classes-buildstats'>
<title><filename>buildstats.bbclass</filename></title>
<para>
The <filename>buildstats</filename> class records
performance statistics about each task executed during the build
(e.g. elapsed time, CPU usage, and I/O usage).
</para>
<para>
When you use this class, the output goes into the
<link linkend='var-BUILDSTATS_BASE'><filename>BUILDSTATS_BASE</filename></link>
directory, which defaults to <filename>${TMPDIR}/buildstats/</filename>.
You can analyze the elapsed time using
<filename>scripts/pybootchartgui/pybootchartgui.py</filename>, which
produces a cascading chart of the entire build process and can be
useful for highlighting bottlenecks.
</para>
<para>
To enable this class, use the
<link linkend='var-USER_CLASSES'><filename>USER_CLASSES</filename></link>
variable from your <filename>local.conf</filename> file.
The <filename>meta-yocto/conf/local.conf.sample</filename> file
in the
<ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
enables this class by default.
</para>
</section>
<section id='ref-classes-ccache'>
<title><filename>ccache.bbclass</filename></title>
<para>
The <filename>ccache</filename> class enables this cache for the build.
This class is used to give a minor performance boost during the build.
However, using the class can lead to unexpected side-effects.
Thus, it is recommended that you do not use this class.
See <ulink url='http://ccache.samba.org/'></ulink> for information on
the C/C++ Compiler Cache.
</para>
</section>
<section id='ref-classes-chrpath'>
<title><filename>chrpath.bbclass</filename></title>
<para>
The <filename>chrpath</filename> class
is a wrapper around the "chrpath" utility, which is used during the
build process for <filename>nativesdk</filename> recipes to change
<filename>RPATH</filename> records within binaries in order to make
them relocatable.
</para>
</section>
<section id='ref-classes-clutter'>
<title><filename>clutter.bbclass</filename></title>
<para>
The <filename>clutter</filename> class consolidates the
major and minor version naming and other common items used by Clutter
and related recipes.
</para>
</section>
<section id='ref-classes-cmake'>
<title><filename>cmake.bbclass</filename></title>
<para>
The <filename>cmake</filename> class allows for
recipes that need to build software using the CMake build system.
You can use the
<link linkend='var-EXTRA_OECMAKE'><filename>EXTRA_OECMAKE</filename></link>
variable to specify additional configuration options to be passed on
the <filename>cmake</filename> command line.
</para>
</section>
<section id='ref-classes-cml1'>
<title><filename>cml1.bbclass</filename></title>
<para>
The <filename>cml1</filename> class provides basic support for the
Linux kernel style build configuration system.
</para>
</section>
<section id='ref-classes-copyleft_compliance'>
<title><filename>copyleft_compliance.bbclass</filename></title>
<para>
The <filename>copyleft_compliance</filename> class
preserves source code for the purposes of license compliance.
This class is an alternative to the <filename>archive*</filename>
classes and is still used by some users even though it has been
deprecated in favor of the
<link linkend='ref-classes-archiver'><filename>archive*</filename></link>
classes.
</para>
</section>
<section id='ref-classes-core-image'>
<title><filename>core-image.bbclass</filename></title>
<para>
The <filename>core-image</filename> class
provides common definitions for the
<filename>core-image-*</filename> image recipes, such as support for
additional
<link linkend='var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></link>.
</para>
</section>
<section id='ref-classes-cpan'>
<title><filename>cpan.bbclass</filename></title>
<para>
The <filename>cpan</filename> class supports Perl modules.
</para>
<para>
Recipes for Perl modules are simple.
These recipes usually only need to point to the source's archive and
then inherit the proper class file.
Building is split into two methods depending on which method the module
authors used.
<itemizedlist>
<listitem><para>Modules that use old
<filename>Makefile.PL</filename>-based build system require
<filename>cpan.bbclass</filename> in their recipes.
</para></listitem>
<listitem><para>Modules that use
<filename>Build.PL</filename>-based build system require
using <filename>cpan_build.bbclass</filename> in their recipes.
</para></listitem>
</itemizedlist>
</para>
</section>
<section id='ref-classes-cross'>
<title><filename>cross.bbclass</filename></title>
<para>
The <filename>cross</filename>)class provides support for
cross-compilation tools.
</para>
</section>
<section id='ref-classes-cross-canadian'>
<title><filename>cross-canadian.bbclass</filename></title>
<para>
The <filename>cross-canadian</filename> class
provides support for Canadian Cross compilation tools for SDKs.
See the
"<link linkend='cross-development-toolchain-generation'>Cross-Development Toolchain Generation</link>"
section for more discussion on these cross-compilation tools.
</para>
</section>
<section id='ref-classes-crosssdk'>
<title><filename>crosssdk.bbclass</filename></title>
<para>
The <filename>crosssdk</filename> class
provides support for cross-compilation tools used for building
SDKs.
See the
"<link linkend='cross-development-toolchain-generation'>Cross-Development Toolchain Generation</link>"
section for more discussion on these cross-compilation tools.
</para>
</section>
<section id='ref-classes-debian'>
<title><filename>debian.bbclass</filename></title>
<para>
The <filename>debian</filename> class renames packages so that they
follow the Debian naming policy (i.e. <filename>eglibc</filename>
becomes <filename>libc6</filename> and <filename>eglibc-devel</filename>
becomes <filename>libc6-dev</filename>.)
</para>
</section>
<section id='ref-classes-deploy'>
<title><filename>deploy.bbclass</filename></title>
<para>
The <filename>deploy</filename> class handles deploying files
to the
<link linkend='var-DEPLOY_DIR_IMAGE'><filename>DEPLOY_DIR_IMAGE</filename></link>
directory.
The main function of this class is to allow the deploy step to be
accelerated by shared state.
Recipes that inherit this class should define their own
<filename>do_deploy</filename> function to copy the files to be
deployed to
<link linkend='var-DEPLOY_DIR'><filename>DEPLOYDIR</filename></link>,
and use <filename>addtask</filename> to add the task at the appropriate
place, which is usually after <filename>do_compile</filename> or
<filename>do_install</filename>.
</para>
</section>
<section id='ref-classes-devshell'>
<title><filename>devshell.bbclass</filename></title>
<para>
The <filename>devshell</filename> class adds the
<filename>devshell</filename> task.
Distribution policy dictates whether to include this class.
See the
"<ulink url='&YOCTO_DOCS_DEV_URL;#platdev-appdev-devshell'>Using a Development Shell</ulink>" section
in the Yocto Project Development Manual for more information about
using <filename>devshell</filename>.
</para>
</section>
<section id='ref-classes-distro_features_check'>
<title><filename>distro_features_check.bbclass</filename></title>
<para>
The <filename>distro_features_check</filename> class
allows individual recipes to check for required and conflicting
<link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>.
</para>
<para>
This class provides support for the
<link linkend='var-REQUIRED_DISTRO_FEATURES'><filename>REQUIRED_DISTRO_FEATURES</filename></link>
and
<link linkend='var-CONFLICT_DISTRO_FEATURES'><filename>CONFLICT_DISTRO_FEATURES</filename></link>
variables.
If any conditions specified in the recipe using the above variables are
not met, the recipe will be skipped.
</para>
</section>
<section id='ref-classes-distrodata'>
<title><filename>distrodata.bbclass</filename></title>
<para>
The <filename>distrodata</filename> class
provides for automatic checking for upstream recipe updates.
</para>
</section>
<section id='ref-classes-distutils'>
<title><filename>distutils.bbclass</filename></title>
<para>
The <filename>distutils</filename> class supports recipes for Python
extensions, which are simple.
These recipes usually only need to point to the source's archive and
then inherit the proper class.
Building is split into two methods depending on which method the
module authors used.
<itemizedlist>
<listitem><para>Extensions that use an Autotools-based build system
require Autotools and
<filename>distutils</filename>-based classes in their recipes.
</para></listitem>
<listitem><para>Extensions that use
<filename>distutils</filename>-based build systems require
the <filename>distutils</filename> class in their recipes.
</para></listitem>
<listitem><para>Extensions that use the setuptools-based build
systems require the
<link linkend='ref-classes-setuptools'><filename>setuptools</filename></link>
class in their recipes.
</para></listitem>
</itemizedlist>
</para>
</section>
<section id='ref-classes-extrausers'>
<title><filename>extrausers.bbclass</filename></title>
<para>
The <filename>extrausers</filename> class allows
additional user and group configuration to be applied at the image
level.
Inheriting this class either globally or from an image recipe allows
additional user and group operations to be performed using the
<link linkend='var-EXTRA_USERS_PARAMS'><filename>EXTRA_USERS_PARAMS</filename></link>
variable.
<note>
The user and group operations added using the
<filename>extrausers</filename> class are not tied to a specific
recipe but can be performed across the image as a whole.
See the
<link linkend='ref-classes-useradd'><filename>useradd</filename></link>
class for information on how to add user and group configuration
to a specific recipe.
</note>
</para>
<para>
Here is an example that uses this class in an image recipe:
<literallayout class='monospaced'>
inherit extrausers
EXTRA_USERS_PARAMS = "\
useradd -p '' tester; \
groupadd developers; \
userdel nobody; \
groupdel -g video; \
groupmod -g 1020 developers; \
usermod -s /bin/sh tester; \
"
</literallayout>
</para>
</section>
<section id='ref-classes-fontcache'>
<title><filename>fontcache.bbclass</filename></title>
<para>
The <filename>fontcache</filename> class generates the
proper post-install and post-remove (postinst and postrm)
scriptlets for font packages.
These scriptlets call <filename>fc-cache</filename> (part of
<filename>Fontconfig</filename>) to add the fonts to the font
information cache.
Since the cache files are architecture-specific,
<filename>fc-cache</filename> runs using QEMU if the postinst
scriptlets need to be run on the build host during image creation.
</para>
<para>
If the fonts being installed are in packages other than the main
package, set
<link linkend='var-FONT_PACKAGES'><filename>FONT_PACKAGES</filename></link>
to include the packages containing the fonts.
</para>
</section>
<section id='ref-classes-gconf'>
<title><filename>gconf.bbclass</filename></title>
<para>
The <filename>gconf</filename> class provides common
functionality for recipes that need to install GConf schemas.
The schemas will be put into a separate package
(<filename>${</filename><link linkend='var-PN'><filename>PN</filename></link><filename>}-gconf</filename>)
that is created automatically when this class is inherited.
This package uses the appropriate post-install and post-remove
(postinst/postrm) scriptlets to register and unregister the schemas
in the target image.
</para>
</section>
<section id='ref-classes-gettext'>
<title><filename>gettext.bbclass</filename></title>
<para>
The <filename>gettext</filename> class provides support for
building software that uses the GNU <filename>gettext</filename>
internationalization and localization system.
All recipes building software that use
<filename>gettext</filename> should inherit this class.
</para>
</section>
<section id='ref-classes-gnome'>
<title><filename>gnome.bbclass</filename></title>
<para>
The <filename>gnome</filename> class supports recipes that
build software from the GNOME stack.
This class inherits the
<link linkend='ref-classes-gnomebase'><filename>gnomebase</filename></link>,
<link linkend='ref-classes-gtk-icon-cache'><filename>gtk-icon-cache</filename></link>,
<link linkend='ref-classes-gconf'><filename>gconf</filename></link> and
<link linkend='ref-classes-mime'><filename>mime</filename></link> classes.
The class also disables GLib Object System (Gobject) introspection
where applicable.
</para>
</section>
<section id='ref-classes-gnomebase'>
<title><filename>gnomebase.bbclass</filename></title>
<para>
The <filename>gnomebase</filename> class is the base
class for recipes that build software from the GNOME stack.
</para>
</section>
<section id='ref-classes-grub-efi'>
<title><filename>grub-efi.bbclass</filename></title>
<para>
The <filename>grub-efi</filename>
class provides <filename>grub-efi</filename>-specific functions for
building bootable images.
</para>
<para>
This class supports several variables:
<itemizedlist>
<listitem><para>
<link linkend='var-INITRD'><filename>INITRD</filename></link>:
Indicates a filesystem image to use as an initrd (optional).
</para></listitem>
<listitem><para>
<link linkend='var-ROOTFS'><filename>ROOTFS</filename></link>:
Indicates a filesystem image to include as the root filesystem
(optional).</para></listitem>
<listitem><para>
<link linkend='var-GRUB_GFXSERIAL'><filename>GRUB_GFXSERIAL</filename></link>:
Set this to "1" to have graphics and serial in the boot menu.
</para></listitem>
<listitem><para>
<link linkend='var-LABELS'><filename>LABELS</filename></link>:
A list of targets for the automatic configuration.
</para></listitem>
<listitem><para>
<link linkend='var-APPEND'><filename>APPEND</filename></link>:
An override list of append strings for each
<filename>LABEL</filename>.
</para></listitem>
<listitem><para>
<link linkend='var-GRUB_OPTS'><filename>GRUB_OPTS</filename></link>:
Additional options to add to the configuration (optional).
Options are delimited using semi-colon characters
(<filename>;</filename>).</para></listitem>
<listitem><para>
<link linkend='var-GRUB_TIMEOUT'><filename>GRUB_TIMEOUT</filename></link>:
Timeout before executing the default <filename>LABEL</filename>
(optional).
</para></listitem>
</itemizedlist>
</para>
</section>
<section id='ref-classes-gsettings'>
<title><filename>gsettings.bbclass</filename></title>
<para>
The <filename>gsettings</filename> class
provides common functionality for recipes that need to install
GSettings (glib) schemas.
The schemas are assumed to be part of the main package.
Appropriate post-install and post-remove (postinst/postrm)
scriptlets are added to register and unregister the schemas in the
target image.
</para>
</section>
<section id='ref-classes-gtk-doc'>
<title><filename>gtk-doc.bbclass</filename></title>
<para>
The <filename>gtk-doc</filename> class
is a helper class to pull in the appropriate
<filename>gtk-doc</filename> dependencies and disable
<filename>gtk-doc</filename>.
</para>
</section>
<section id='ref-classes-gtk-icon-cache'>
<title><filename>gtk-icon-cache.bbclass</filename></title>
<para>
The <filename>gtk-icon-cache</filename> class
Generates the proper post-install and post-remove (postinst/postrm)
scriptlets for packages that use GTK+ and install icons.
These scriptlets call <filename>gtk-update-icon-cache</filename> to add
the fonts to GTK+'s icon cache.
Since the cache files are architecture-specific,
<filename>gtk-update-icon-cache</filename> is run using QEMU if the
postinst scriptlets need to be run on the build host during image
creation.
</para>
</section>
<section id='ref-classes-gtk-immodules-cache'>
<title><filename>gtk-immodules-cache.bbclass</filename></title>
<para>
The <filename>gtk-immodules-cache</filename> class
generates the proper post-install and post-remove (postinst/postrm)
scriptlets for packages that install GTK+ input method modules for
virtual keyboards.
These scriptlets call <filename>gtk-update-icon-cache</filename> to add
the input method modules to the cache.
Since the cache files are architecture-specific,
<filename>gtk-update-icon-cache</filename> is run using QEMU if the
postinst scriptlets need to be run on the build host during image
creation.
</para>
<para>
If the input method modules being installed are in packages other than
the main package, set
<link linkend='var-GTKIMMODULES_PACKAGES'><filename>GTKIMMODULES_PACKAGES</filename></link>
to include the packages containing the modules.
</para>
</section>
<section id='ref-classes-gzipnative'>
<title><filename>gzipnative.bbclass</filename></title>
<para>
The <filename>gzipnative</filename>
class enables the use of native versions of <filename>gzip</filename>
and <filename>pigz</filename> rather than the system versions.
</para>
</section>
<section id='ref-classes-icecc'>
<title><filename>icecc.bbclass</filename></title>
<para>
The <filename>icecc</filename> class stages directories with symlinks
from <filename>gcc</filename> and <filename>g++</filename> to
<filename>icecc</filename>, for both native and cross compilers.
Depending on each configure or compile, the OpenEmbedded build system
adds the directories at the head of the <filename>PATH</filename> list
and then sets
<link linkend='var-ICECC_CXX'><filename>ICECC_CXX</filename></link>
and
<link linkend='var-ICECC_CC'><filename>ICEC_CC</filename></link>.
</para>
<para>
For the cross compiler, the class creates a <filename>tar.gz</filename>
file that contains the Yocto Project toolchain and sets
<link linkend='var-ICECC_VERSION'><filename>ICECC_VERSION</filename></link>
accordingly.
</para>
<para>
The class handles all three different compile stages
(i.e native ,cross-kernel and target) and creates the necessary
environment <filename>tar.gz</filename> file to be used by the remote
machines.
The class also supports SDK generation.
</para>
<para>
If <link linkend='var-ICECC_PATH'><filename>ICECC_PATH</filename></link>
is not set in your <filename>local.conf</filename> file, then the
class tries to locate it using <filename>which</filename>.
If
<link linkend='var-ICECC_ENV_EXEC'><filename>ICECC_ENV_EXEC</filename></link>
is set in your <filename>local.conf</filename> file, the variable should
point to the <filename>icecc-create-env</filename> script provided by
the user.
If you do not point to a user-provided script, the build system
uses the default script provided by the recipe
<filename>icecc-create-env.bb</filename>.
<note>
This script is a modified version and not the one that comes with
<filename>icecc</filename>.
</note>
</para>
<para>
If you do not want the Icecream distributed compile support to apply
to specific packages or classes, you can effectively "blacklist" them
by listing the packages and classes using the
<link linkend='var-ICECC_USER_PACKAGE_BL'><filename>ICECC_USER_PACKAGE_BL</filename></link>
and
<link linkend='var-ICECC_USER_CLASS_BL'><filename>ICECC_USER_CLASS_BL</filename></link>,
variables, respectively, in your <filename>local.conf</filename> file.
Doing so causes the OpenEmbedded build system to handle these
compilations locally.
</para>
<para>
Additionally, you can list packages using the
<link linkend='var-ICECC_USER_PACKAGE_WL'><filename>ICECC_USER_PACKAGE_WL</filename></link>
variable in your <filename>local.conf</filename> file to force
<filename>icecc</filename> to be enabled for packages using an empty
<link linkend='var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></link>
variable.
</para>
</section>
<section id='ref-classes-image'>
<title><filename>image.bbclass</filename></title>
<para>
The <filename>image</filename> class helps support creating images
in different formats.
First, the root filesystem is created from packages using
one of the <filename>rootfs_*.bbclass</filename>
files (depending on the package format used) and then the image is
created.
<itemizedlist>
<listitem><para>The
<filename><link linkend='var-IMAGE_FSTYPES'>IMAGE_FSTYPES</link></filename>
variable controls the types of images to generate.
</para></listitem>
<listitem><para>The
<filename><link linkend='var-IMAGE_INSTALL'>IMAGE_INSTALL</link></filename>
variable controls the list of packages to install into the
image.</para></listitem>
</itemizedlist>
</para>
</section>
<section id='ref-classes-image_types'>
<title><filename>image_types.bbclass</filename></title>
<para>
The <filename>image_types</filename> class defines all of
the standard image output types that you can enable through the
<link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>
variable.
You can use this class as a reference on how to add support for custom
image output types.
</para>
<para>
By default, this class is enabled through the
<link linkend='var-IMAGE_CLASSES'><filename>IMAGE_CLASSES</filename></link>
variable in
<link linkend='ref-classes-image'><filename>image.bbclass</filename></link>.
If you define your own image types using a custom BitBake class and
then use <filename>IMAGE_CLASSES</filename> to enable it, the custom
class must either inherit <filename>image_types</filename> or
<filename>image_types</filename> must also appear in
<filename>IMAGE_CLASSES</filename>.
</para>
</section>
<section id='ref-classes-image_types_uboot'>
<title><filename>image_types_uboot.bbclass</filename></title>
<para>
The <filename>image_types_uboot</filename> class
defines additional image types specifically for the U-Boot bootloader.
</para>
</section>
<section id='ref-classes-image-live'>
<title><filename>image-live.bbclass</filename></title>
<para>
The <filename>image-live</filename> class supports building "live"
images.
Normally, you do not use this class directly.
Instead, you add "live" to
<link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>.
</para>
</section>
<section id='ref-classes-image-mklibs'>
<title><filename>image-mklibs.bbclass</filename></title>
<para>
The <filename>mklibs</filename> class
enables the use of the <filename>mklibs</filename> utility during the
<filename>do_rootfs</filename> task, which optimizes the size of
libraries contained in the image.
</para>
<para>
The
<link linkend='var-USER_CLASSES'><filename>USER_CLASSES</filename></link>
variable enables this class.
By default, the class is enabled in the
<filename>local.conf.template</filename> in the
<ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
as follows:
<literallayout class='monospaced'>
USER_CLASSES ?= "buildstats image-mklibs image-prelink"
</literallayout>
</para>
</section>
<section id='ref-classes-image-prelink'>
<title><filename>image-prelink.bbclass</filename></title>
<para>
The <filename>image-prelink</filename> class
enables the use of the <filename>prelink</filename> utility during
the <filename>do_rootfs</filename> task, which optimizes the dynamic
linking of shared libraries to reduce executable startup time.
</para>
<para>
The
<link linkend='var-USER_CLASSES'><filename>USER_CLASSES</filename></link>
variable enables this class.
By default, the class is enabled in the
<filename>local.conf.template</filename> in the
<ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
as follows:
<literallayout class='monospaced'>
USER_CLASSES ?= "buildstats image-mklibs image-prelink"
</literallayout>
</para>
</section>
<section id='ref-classes-image-swab'>
<title><filename>image-swab.bbclass</filename></title>
<para>
The <filename>image-swab</filename> class enables the
<ulink url='&YOCTO_HOME_URL;/tools-resources/projects/swabber'>Swabber</ulink>
tool in order to detect and log accesses to the host system during
the OpenEmbedded build process.
<note>
This class is currently unmaintained.
</note>
</para>
</section>
<section id='ref-classes-image-vmdk'>
<title><filename>image-vmdk.bbclass</filename></title>
<para>
The <filename>image-vmdk</filename> class supports building VMware
VMDK images.
Normally, you do not use this class directly.
Instead, you add "vmdk" to
<link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>.
</para>
</section>
<section id='ref-classes-insane'>
<title><filename>insane.bbclass</filename></title>
<para>
The <filename>insane</filename> class adds a step to the package
generation process so that output quality assurance checks are
generated by the OpenEmbedded build system.
A range of checks are performed that check the build's output
for common problems that show up during runtime.
Distribution policy usually dictates whether to include this class.
</para>
<para>
You can configure the sanity checks so that specific test failures
either raise a warning or an error message.
Typically, failures for new tests generate a warning.
Subsequent failures for the same test would then generate an error
message once the metadata is in a known and good condition.
</para>
<para>
Use the
<link linkend='var-WARN_QA'><filename>WARN_QA</filename></link> and
<link linkend='var-ERROR_QA'><filename>ERROR_QA</filename></link>
variables to control the behavior of
these checks at the global level (i.e. in your custom distro
configuration).
However, to skip one or more checks in recipes, you should use
<link linkend='var-INSANE_SKIP'><filename>INSANE_SKIP</filename></link>.
For example, to skip the check for symbolic link
<filename>.so</filename> files in the main package of a recipe,
add the following to the recipe.
You need to realize that the package name override, in this example
<filename>${PN}</filename>, must be used:
<literallayout class='monospaced'>
INSANE_SKIP_${PN} += "dev-so"
</literallayout>
Please keep in mind that the QA checks exist in order to detect real
or potential problems in the packaged output.
So exercise caution when disabling these checks.
</para>
<para>
The following list shows the tests you can list with the
<filename>WARN_QA</filename> and <filename>ERROR_QA</filename>
variables:
<itemizedlist>
<listitem><para><emphasis><filename>ldflags:</filename></emphasis>
Ensures that the binaries were linked with the
<filename>LDFLAGS</filename> options provided by the build system.
If this test fails, check that the <filename>LDFLAGS</filename> variable
is being passed to the linker command.</para></listitem>
<listitem><para><emphasis><filename>useless-rpaths:</filename></emphasis>
Checks for dynamic library load paths (rpaths) in the binaries that
by default on a standard system are searched by the linker (e.g.
<filename>/lib</filename> and <filename>/usr/lib</filename>).
While these paths will not cause any breakage, they do waste space and
are unnecessary.</para></listitem>
<listitem><para><emphasis><filename>rpaths:</filename></emphasis>
Checks for rpaths in the binaries that contain build system paths such
as <filename>TMPDIR</filename>.
If this test fails, bad <filename>-rpath</filename> options are being
passed to the linker commands and your binaries have potential security
issues.</para></listitem>
<listitem><para><emphasis><filename>dev-so:</filename></emphasis>
Checks that the <filename>.so</filename> symbolic links are in the
<filename>-dev</filename> package and not in any of the other packages.
In general, these symlinks are only useful for development purposes.
Thus, the <filename>-dev</filename> package is the correct location for
them.
Some very rare cases do exist for dynamically loaded modules where
these symlinks are needed instead in the main package.
</para></listitem>
<listitem><para><emphasis><filename>debug-files:</filename></emphasis>
Checks for <filename>.debug</filename> directories in anything but the
<filename>-dbg</filename> package.
The debug files should all be in the <filename>-dbg</filename> package.
Thus, anything packaged elsewhere is incorrect packaging.</para></listitem>
<listitem><para><emphasis><filename>arch:</filename></emphasis>
Checks the Executable and Linkable Format (ELF) type, bit size, and endianness
of any binaries to ensure they match the target architecture.
This test fails if any binaries don't match the type since there would be an
incompatibility.
Sometimes software, like bootloaders, might need to bypass this check.
</para></listitem>
<listitem><para><emphasis><filename>debug-deps:</filename></emphasis>
Checks that <filename>-dbg</filename> packages only depend on other
<filename>-dbg</filename> packages and not on any other types of packages,
which would cause a packaging bug.</para></listitem>
<listitem><para><emphasis><filename>dev-deps:</filename></emphasis>
Checks that <filename>-dev</filename> packages only depend on other
<filename>-dev</filename> packages and not on any other types of packages,
which would be a packaging bug.</para></listitem>
<listitem><para><emphasis><filename>pkgconfig:</filename></emphasis>
Checks <filename>.pc</filename> files for any
<link linkend='var-TMPDIR'><filename>TMPDIR</filename></link>/<link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>
paths.
Any <filename>.pc</filename> file containing these paths is incorrect
since <filename>pkg-config</filename> itself adds the correct sysroot prefix
when the files are accessed.</para></listitem>
<listitem><para><emphasis><filename>textrel:</filename></emphasis>
Checks for ELF binaries that contain relocations in their
<filename>.text</filename> sections, which can result in a
performance impact at runtime.</para></listitem>
<listitem><para><emphasis><filename>pkgvarcheck:</filename></emphasis>
Checks through the variables
<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>,
<link linkend='var-RRECOMMENDS'><filename>RRECOMMENDS</filename></link>,
<link linkend='var-RSUGGESTS'><filename>RSUGGESTS</filename></link>,
<link linkend='var-RCONFLICTS'><filename>RCONFLICTS</filename></link>,
<link linkend='var-RPROVIDES'><filename>RPROVIDES</filename></link>,
<link linkend='var-RREPLACES'><filename>RREPLACES</filename></link>,
<link linkend='var-FILES'><filename>FILES</filename></link>,
<link linkend='var-ALLOW_EMPTY'><filename>ALLOW_EMPTY</filename></link>,
<filename>pkg_preinst</filename>,
<filename>pkg_postinst</filename>,
<filename>pkg_prerm</filename>
and <filename>pkg_postrm</filename>, and reports if there are
variable sets that are not package-specific.
Using these variables without a package suffix is bad practice,
and might unnecessarily complicate dependencies of other packages
within the same recipe or have other unintended consequences.
</para></listitem>
<listitem><para><emphasis><filename>xorg-driver-abi:</filename></emphasis>
Checks that all packages containing Xorg drivers have ABI
dependencies.
The <filename>xserver-xorg</filename> recipe provides driver
ABI names.
All drivers should depend on the ABI versions that they have
been built against.
Driver recipes that include
<filename>xorg-driver-input.inc</filename>
or <filename>xorg-driver-video.inc</filename> will
automatically get these versions.
Consequently, you should only need to explicitly add
dependencies to binary driver recipes.
</para></listitem>
<listitem><para><emphasis><filename>libexec:</filename></emphasis>
Checks if a package contains files in
<filename>/usr/libexec</filename>.
This check is not performed if the
<filename>libexecdir</filename> variable has been set
explicitly to <filename>/usr/libexec</filename>.
</para></listitem>
<listitem><para><emphasis><filename>staticdev:</filename></emphasis>
Checks for static library files (<filename>*.a</filename>) in
non-<filename>staticdev</filename> packages.
</para></listitem>
<listitem><para><emphasis><filename>la:</filename></emphasis>
Checks <filename>.la</filename> files for any <filename>TMPDIR</filename>
paths.
Any <filename>.la</filename> file containing these paths is incorrect since
<filename>libtool</filename> adds the correct sysroot prefix when using the
files automatically itself.</para></listitem>
<listitem><para><emphasis><filename>desktop:</filename></emphasis>
Runs the <filename>desktop-file-validate</filename> program
against any <filename>.desktop</filename> files to validate
their contents against the specification for
<filename>.desktop</filename> files.</para></listitem>
<listitem><para><emphasis><filename>already-stripped:</filename></emphasis>
Checks that produced binaries have not already been
stripped prior to the build system extracting debug symbols.
It is common for upstream software projects to default to
stripping debug symbols for output binaries.
In order for debugging to work on the target using
<filename>-dbg</filename> packages, this stripping must be
disabled.
</para></listitem>
<listitem><para><emphasis><filename>split-strip:</filename></emphasis>
Reports that splitting or stripping debug symbols from binaries
has failed.
</para></listitem>
<listitem><para><emphasis><filename>arch:</filename></emphasis>
Checks to ensure the architecture, bit size, and endianness
of all output binaries matches that of the target.
This test can detect when the wrong compiler or compiler options
have been used.
</para></listitem>
<listitem><para><emphasis><filename>installed-vs-shipped:</filename></emphasis>
Reports when files have been installed within
<filename>do_install</filename> but have not been included in
any package by way of the
<link linkend='var-FILES'><filename>FILES</filename></link>
variable.
Files that do not appear in any package cannot be present in
an image later on in the build process.
Ideally, all installed files should be packaged or not
installed at all.
These files can be deleted at the end of
<filename>do_install</filename> if the files are not
needed in any package.
</para></listitem>
<listitem><para><emphasis><filename>dep-cmp:</filename></emphasis>
Checks for invalid version comparison statements in runtime
dependency relationships between packages (i.e. in
<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>,
<link linkend='var-RRECOMMENDS'><filename>RRECOMMENDS</filename></link>,
<link linkend='var-RSUGGESTS'><filename>RSUGGESTS</filename></link>,
<link linkend='var-RPROVIDES'><filename>RPROVIDES</filename></link>,
<link linkend='var-RREPLACES'><filename>RREPLACES</filename></link>,
and
<link linkend='var-RCONFLICTS'><filename>RCONFLICTS</filename></link>
variable values).
Any invalid comparisons might trigger failures or undesirable
behavior when passed to the package manager.
</para></listitem>
<listitem><para><emphasis><filename>files-invalid:</filename></emphasis>
Checks for
<link linkend='var-FILES'><filename>FILES</filename></link>
variable values that contain "//", which is invalid.
</para></listitem>
<listitem><para><emphasis><filename>incompatible-license:</filename></emphasis>
Report when packages are excluded from being created due to
being marked with a license that is in
<link linkend='var-INCOMPATIBLE_LICENSE'><filename>INCOMPATIBLE_LICENSE</filename></link>.
</para></listitem>
<listitem><para><emphasis><filename>compile-host-path:</filename></emphasis>
Checks the <filename>do_compile</filename> log for indications
that paths to locations on the build host were used.
Using such paths might result in host contamination of the
build output.
</para></listitem>
<listitem><para><emphasis><filename>install-host-path:</filename></emphasis>
Checks the <filename>do_install</filename> log for indications
that paths to locations on the build host were used.
Using such paths might result in host contamination of the
build output.
</para></listitem>
<listitem><para><emphasis><filename>libdir:</filename></emphasis>
Checks for libraries being installed into incorrect
(possibly hardcoded) installation paths.
For example, this test will catch recipes that install
<filename>/lib/bar.so</filename> when
<filename>${base_libdir}</filename> is "lib32".
Another example is when recipes install
<filename>/usr/lib64/foo.so</filename> when
<filename>${libdir}</filename> is "/usr/lib".
</para></listitem>
<listitem><para><emphasis><filename>packages-list:</filename></emphasis>
Checks for the same package being listed multiple times through
the <link linkend='var-PACKAGES'><filename>PACKAGES</filename></link>
variable value.
Installing the package in this manner can cause errors during
packaging.
</para></listitem>
<listitem><para><emphasis><filename>perm-config:</filename></emphasis>
Reports lines in <filename>fs-perms.txt</filename> that have
an invalid format.
</para></listitem>
<listitem><para><emphasis><filename>perm-line:</filename></emphasis>
Reports lines in <filename>fs-perms.txt</filename> that have
an invalid format.
</para></listitem>
<listitem><para><emphasis><filename>perm-link:</filename></emphasis>
Reports lines in <filename>fs-perms.txt</filename> that
specify 'link' where the specified target already exists.
</para></listitem>
<listitem><para><emphasis><filename>pkgname:</filename></emphasis>
Checks that all packages in
<link linkend='var-PACKAGES'><filename>PACKAGES</filename></link>
have names that do not contain invalid characters (i.e.
characters other than 0-9, a-z, ., +, and -).
</para></listitem>
<listitem><para><emphasis><filename>pn-overrides:</filename></emphasis>
Checks that a recipe does not have a name
(<link linkend='var-PN'><filename>PN</filename></link>) value
that appears in
<link linkend='var-OVERRIDES'><filename>OVERRIDES</filename></link>.
If a recipe is named such that its <filename>PN</filename>
value matches something already in
<filename>OVERRIDES</filename> (e.g. <filename>PN</filename>
happens to be the same as
<link linkend='var-MACHINE'><filename>MACHINE</filename></link>
or
<link linkend='var-DISTRO'><filename>DISTRO</filename></link>),
it can have unexpected consequences.
For example, assignments such as
<filename>FILES_${PN} = "xyz"</filename> effectively turn into
<filename>FILES = "xyz"</filename>.
</para></listitem>
<listitem><para><emphasis><filename>unsafe-references-in-binaries:</filename></emphasis>
Reports when a binary installed in
<filename>${base_libdir}</filename>,
<filename>${base_bindir}</filename>, or
<filename>${base_sbindir}</filename>, depends on another
binary installed under <filename>${exec_prefix}</filename>.
This dependency is a concern if you want the system to remain
basically operable if <filename>/usr</filename> is mounted
separately and is not mounted.
<note>
Defaults for binaries installed in
<filename>${base_libdir}</filename>,
<filename>${base_bindir}</filename>, and
<filename>${base_sbindir}</filename> are
<filename>/lib</filename>, <filename>/bin</filename>, and
<filename>/sbin</filename>, respectively.
The default for a binary installed
under <filename>${exec_prefix}</filename> is
<filename>/usr</filename>.
</note>
</para></listitem>
<listitem><para><emphasis><filename>unsafe-references-in-scripts:</filename></emphasis>
Reports when a script file installed in
<filename>${base_libdir}</filename>,
<filename>${base_bindir}</filename>, or
<filename>${base_sbindir}</filename>, depends on files
installed under <filename>${exec_prefix}</filename>.
This dependency is a concern if you want the system to remain
basically operable if <filename>/usr</filename> is mounted
separately and is not mounted.
<note>
Defaults for binaries installed in
<filename>${base_libdir}</filename>,
<filename>${base_bindir}</filename>, and
<filename>${base_sbindir}</filename> are
<filename>/lib</filename>, <filename>/bin</filename>, and
<filename>/sbin</filename>, respectively.
The default for a binary installed
under <filename>${exec_prefix}</filename> is
<filename>/usr</filename>.
</note>
</para></listitem>
<listitem><para><emphasis><filename>var-undefined:</filename></emphasis>
Reports when variables fundamental to packaging (i.e.
<link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>,
<link linkend='var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></link>,
<link linkend='var-D'><filename>D</filename></link>,
<link linkend='var-PN'><filename>PN</filename></link>, and
<link linkend='var-PKGD'><filename>PKGD</filename></link>) are
undefined during <filename>do_package</filename>.
</para></listitem>
<listitem><para><emphasis><filename>pkgv-undefined:</filename></emphasis>
Checks to see if the <filename>PKGV</filename> variable
is undefined during <filename>do_package</filename>.
</para></listitem>
<listitem><para><emphasis><filename>buildpaths:</filename></emphasis>
Checks for paths to locations on the build host inside the
output files.
Currently, this test triggers too many false positives and
thus is not normally enabled.
</para></listitem>
<listitem><para><emphasis><filename>perms:</filename></emphasis>
Currently, this check is unused but reserved.
</para></listitem>
<listitem><para><emphasis><filename>version-going-backwards:</filename></emphasis>
If Build History is enabled, reports when a package
being written out has a lower version than the previously
written package under the same name.
If you are placing output packages into a feed and
upgrading packages on a target system using that feed, the
version of a package going backwards can result in the target
system not correctly upgrading to the "new" version of the
package.
<note>
If you are not using runtime package management on your
target system, then you do not need to worry about
this situation.
</note>
</para></listitem>
</itemizedlist>
</para>
</section>
<section id='ref-classes-insserve'>
<title><filename>insserve.bbclass</filename></title>
<para>
The <filename>insserve</filename> class
uses the <filename>insserv</filename> utility to update the order of
symbolic links in <filename>/etc/rc?.d/</filename> within an image
based on dependencies specified by LSB headers in the
<filename>init.d</filename> scripts themselves.
</para>
</section>
<section id='ref-classes-kernel'>
<title><filename>kernel.bbclass</filename></title>
<para>
The <filename>kernel</filename> class handles building Linux kernels.
The class contains code to build all kernel trees.
All needed headers are staged into the
<filename><link linkend='var-STAGING_KERNEL_DIR'>STAGING_KERNEL_DIR</link></filename>
directory to allow out-of-tree module builds using <filename>module.bbclass</filename>.
</para>
<para>
This means that each built kernel module is packaged separately and inter-module
dependencies are created by parsing the <filename>modinfo</filename> output.
If all modules are required, then installing the <filename>kernel-modules</filename>
package installs all packages with modules and various other kernel packages
such as <filename>kernel-vmlinux</filename>.
</para>
<para>
Various other classes are used by the kernel and module classes internally including
<filename>kernel-arch.bbclass</filename>, <filename>module_strip.bbclass</filename>,
<filename>module-base.bbclass</filename>, and <filename>linux-kernel-base.bbclass</filename>.
</para>
</section>
<section id='ref-classes-kernel-arch'>
<title><filename>kernel-arch.bbclass</filename></title>
<para>
The <filename>kernel-arch</filename> class
sets the <filename>ARCH</filename> environment variable for Linux
kernel compilation (including modules).
</para>
</section>
<section id='ref-classes-kernel-module-split'>
<title><filename>kernel-module-split.bbclass</filename></title>
<para>
The <filename>kernel-module-split</filename> class
provides common functionality for splitting Linux kernel modules into
separate packages.
</para>
</section>
<section id='ref-classes-kernel-yocto'>
<title><filename>kernel-yocto.bbclass</filename></title>
<para>
The <filename>kernel-yocto</filename> class
provides common functionality for building from linux-yocto style
kernel source repositories.
</para>
</section>
<section id='ref-classes-lib_package'>
<title><filename>lib_package.bbclass</filename></title>
<para>
The <filename>lib_package</filename> class
supports recipes that build libraries and produce executable
binaries, where those binaries should not be installed by default
along with the library.
Instead, the binaries are added to a separate
<filename>${</filename><link linkend='var-PN'><filename>PN</filename></link><filename>}-bin</filename>
package to make their installation optional.
</para>
</section>
<section id='ref-classes-license'>
<title><filename>license.bbclass</filename></title>
<para>
The <filename>license</filename> class provides license
manifest creation and license exclusion.
This class is enabled by default using the default value for the
<link linkend='var-INHERIT_DISTRO'><filename>INHERIT_DISTRO</filename></link>
variable.
</para>
</section>
<section id='ref-classes-linux-kernel-base'>
<title><filename>linux-kernel-base.bbclass</filename></title>
<para>
The <filename>linux-kernel-base</filename> class
provides common functionality for recipes that build out of the Linux
kernel source tree.
These builds goes beyond the kernel itself.
For example, the Perf recipe also inherits this class.
</para>
</section>
<section id='ref-classes-logging'>
<title><filename>logging.bbclass</filename></title>
<para>
The <filename>logging</filename> class provides the standard
shell functions used to log messages for various BitBake severity levels
(i.e. <filename>bbplain</filename>, <filename>bbnote</filename>,
<filename>bbwarn</filename>, <filename>bberror</filename>,
<filename>bbfatal</filename>, and <filename>bbdebug</filename>.
</para>
<para>
This class is enabled by default since it is inherited by
the <filename>base</filename> class.
</para>
</section>
<section id='ref-classes-meta'>
<title><filename>meta.bbclass</filename></title>
<para>
The <filename>meta</filename> class is inherited by recipes
that do not build any output packages themselves, but act as a "meta"
target for building other recipes.
</para>
</section>
<section id='ref-classes-metadata_scm'>
<title><filename>metadata_scm.bbclass</filename></title>
<para>
The <filename>metadata_scm</filename> class provides functionality for
querying the branch and revision of a Source Code Manager (SCM)
repository.
</para>
<para>
The <link linkend='ref-classes-base'><filename>base</filename></link>
class uses this class to print the revisions of each layer before
starting every build.
The <filename>metadata_scm</filename> class is enabled by default
because it is inherited by the <filename>base</filename> class.
</para>
</section>
<section id='ref-classes-mime'>
<title><filename>mime.bbclass</filename></title>
<para>
The <filename>mime</filename> class generates the proper
post-install and post-remove (postinst/postrm) scriptlets for packages
that install MIME type files.
These scriptlets call <filename>update-mime-database</filename> to add
the MIME types to the shared database.
</para>
</section>
<section id='ref-classes-mirrors'>
<title><filename>mirrors.bbclass</filename></title>
<para>
The <filename>mirrors</filename> class sets up some standard
<link linkend='var-MIRRORS'><filename>MIRRORS</filename></link> entries
for source code mirrors.
These mirrors provide a fall-back path in case the upstream source
specified in
<link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>
within recipes is unavailable.
</para>
<para>
This class is enabled by default since it is inherited by the
<link linkend='ref-classes-base'><filename>base</filename></link> class.
</para>
</section>
<section id='ref-classes-multilib*'>
<title><filename>multilib*.bbclass</filename></title>
<para>
The Multilib (<filename>multilib*</filename>) classes provide support
for building libraries with different target optimizations or target
architectures and installing them side-by-side in the same image.
</para>
<para>
For more information on using the Multilib feature, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#combining-multiple-versions-library-files-into-one-image'>Combining Multiple Versions of Library Files into One Image</ulink>"
section in the Yocto Project Development Manual.
</para>
</section>
<section id='ref-classes-native'>
<title><filename>native.bbclass</filename></title>
<para>
The native (<filename>native</filename>) class provides common
functionality for recipes that wish to build tools to run on the build
host (i.e. tools that use the compiler or other tools from the
build host).
</para>
<para>
You can create a recipe that builds tools that run natively on the
host a couple different ways:
<itemizedlist>
<listitem><para>Create a <filename>myrecipe-native.bb</filename>
that inherits the <filename>native</filename> class.
</para></listitem>
<listitem><para>Create or modify a target recipe that has adds
the following:
<literallayout class='monospaced'>
<link linkend='var-BBCLASSEXTEND'><filename>BBCLASSEXTEND</filename></link> = "native"
</literallayout>
Inside the recipe, use <filename>_class-native</filename> and
<filename>_class-target</filename> overrides to specify any
functionality specific to the respective native or target
case.</para></listitem>
</itemizedlist>
</para>
<para>
Although applied differently, the <filename>native</filename> class is
used with both methods.
The advantage of the second method is that you do not need to have two
separate recipes (assuming you need both) for native and target.
All common parts of the recipe are automatically shared.
</para>
</section>
<section id='ref-classes-nativesdk'>
<title><filename>nativesdk.bbclass</filename></title>
<para>
The native SDK (<filename>nativesdk</filename>) class provides common
functionality for recipes that wish to build tools to run as part of
an SDK (i.e. tools that run on
<link linkend='var-SDKMACHINE'><filename>SDKMACHINE</filename></link>).
</para>
<para>
You can create a recipe that builds tools that run on the SDK machine
a couple different ways:
<itemizedlist>
<listitem><para>Create a <filename>myrecipe-native.bb</filename>
that inherits the <filename>nativesdk</filename> class.
</para></listitem>
<listitem><para>Create a <filename>nativesdk</filename> variant
of any recipe by adding the following:
<literallayout class='monospaced'>
<link linkend='var-BBCLASSEXTEND'><filename>BBCLASSEXTEND</filename></link> = "nativesdk"
</literallayout>
Inside the recipe, use <filename>_class-nativesdk</filename> and
<filename>_class-target</filename> overrides to specify any
functionality specific to the respective SDK machine or target
case.</para></listitem>
</itemizedlist>
</para>
<para>
Although applied differently, the <filename>nativesdk</filename> class
is used with both methods.
The advantage of the second method is that you do not need to have two
separate recipes (assuming you need both) for the SDK machine and the
target.
All common parts of the recipe are automatically shared.
</para>
</section>
<section id='ref-classes-oelint'>
<title><filename>oelint.bbclass</filename></title>
<para>
The OpenEmbedded link (<filename>oelint</filename>) class is an
obsolete lint checking tool that exists in
<filename>meta/classes</filename> in the
<ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
</para>
<para>
A number of classes exist that are could be generally useful in
OE-Core but are never actually used within OE-Core itself.
The <filename>oelint</filename> class is one such example.
However, being aware of this class can reduce the proliferation of
different versions of similar classes across multiple layers.
</para>
</section>
<section id='ref-classes-ownmirrors'>
<title><filename>ownmirrors.bbclass</filename></title>
<para>
The own mirrors (<filename>ownmirrors</filename>) class makes it
easier to set up your own
<link linkend='var-PREMIRRORS'><filename>PREMIRRORS</filename></link>
from which to first fetch source before attempting to fetch it from the
upstream specified in
<link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>
within each recipe.
</para>
<para>
To use this class, inherit it globally and specify
<link linkend='var-SOURCE_MIRROR_URL'><filename>SOURCE_MIRROR_URL</filename></link>.
Here is an example:
<literallayout class='monospaced'>
INHERIT += "own-mirrors"
SOURCE_MIRROR_URL = "http://example.com/my-source-mirror"
</literallayout>
You can specify only a single URL in
<filename>SOURCE_MIRROR_URL</filename>.
</para>
</section>
<section id='ref-classes-pkgconfig'>
<title>Pkg-config - <filename>pkgconfig.bbclass</filename></title>
<para>
<filename>pkg-config</filename> provides a standard way to get
header and library information.
This class aims to smooth integration of
<filename>pkg-config</filename> into libraries that use it.
</para>
<para>
During staging, BitBake installs <filename>pkg-config</filename> data into the
<filename>sysroots/</filename> directory.
By making use of sysroot functionality within <filename>pkg-config</filename>,
this class no longer has to manipulate the files.
</para>
</section>
<section id='ref-classes-packagedata'>
<title><filename>packagedata.bbclass</filename></title>
<para>
The package data (<filename>packagedata</filename>) class provides
common functionality for reading <filename>pkgdata</filename> files
found in
<link linkend='var-PKGDATA_DIR'><filename>PKGDATA_DIR</filename></link>.
These files contain information about each output package produced by
the OpenEmbedded build system.
</para>
<para>
This class is enabled by default because it is inherited by the
<link linkend='ref-classes-package'><filename>package</filename></link>
class.
</para>
</section>
<section id='ref-classes-packageinfo'>
<title><filename>packageinfo.bbclass</filename></title>
<para>
The package information (<filename>packageinfo</filename>) class
gives a BitBake user interface the ability to retrieve information
about output packages from the <filename>pkgdata</filename> files.
</para>
<para>
This class is enabled automatically when using the
<ulink url='&YOCTO_HOME_URL;/tools-resources/projects/hob'>Hob</ulink>
user interface.
</para>
</section>
<section id='ref-classes-patch'>
<title><filename>patch.bbclass</filename></title>
<para>
The <filename>patch</filename> class provides all functionality for
applying patches during the <filename>do_patch</filename> task.
</para>
<para>
This class is enabled by default because it is inherited by the
<link linkend='ref-classes-base'><filename>base</filename></link>
class.
</para>
</section>
<section id='ref-classes-perlnative'>
<title><filename>perlnative.bbclass</filename></title>
<para>
When inherited by a recipe, the <filename>perlnative</filename> class
supports using the native version of Perl built by the build system
rather than using the version provided by the build host.
</para>
</section>
<section id='ref-classes-pixbufcache'>
<title><filename>pixbufcache.bbclass</filename></title>
<para>
The <filename>pixbufcache</filename> class generates the proper
post-install and post-remove (postinst/postrm) scriptlets for packages
that install pixbuf loaders, which are used with
<filename>gdk-pixbuf</filename>.
These scriptlets call <filename>update_pixbuf_cache</filename>
to add the input method modules to the cache.
Since the cache files are architecture-specific,
<filename>update_pixbuf_cache</filename> is run using QEMU if the
postinst scriptlets need to be run on the build host during image
creation.
</para>
<para>
If the pixbuf loaders modules being installed are in packages other
than the main package, set
<link linkend='var-PIXBUF_PACKAGES'><filename>PIXBUF_PACKAGES</filename></link>
to include the packages containing the modules.
</para>
</section>
<section id='ref-classes-populate-sdk'>
<title><filename>populate_sdk.bbclass</filename></title>
<para>
The <filename>populate_sdk</filename> class facilitates compatibility
with SDK-only recipes.
</para>
</section>
<section id='ref-classes-populate-sdk-*'>
<title><filename>populate_sdk_*.bbclass</filename></title>
<para>
The <filename>populate_sdk_*</filename> family of classes support
SDK creation.
This family of classes consists of the following:
<itemizedlist>
<listitem><para><emphasis><filename>populate_sdk_base</filename>:</emphasis>
The base class supporting SDK creation under all package
managers (i.e. DEB, RPM, and IPK).</para></listitem>
<listitem><para><emphasis><filename>populate_sdk_deb</filename>:</emphasis>
Supports creation of the SDK given the Debian package manager.
</para></listitem>
<listitem><para><emphasis><filename>populate_sdk_rpm</filename>:</emphasis>
Supports creation of the SDK given the RPM package manager.
</para></listitem>
<listitem><para><emphasis><filename>populate_sdk_ipk</filename>:</emphasis>
Supports creation of the SDK given the IPK package manager.
</para></listitem>
</itemizedlist>
</para>
<para>
The <filename>populate_sdk_base</filename> package inherits the
appropriate <filename>populate_sdk_*</filename> (i.e.
<filename>deb</filename>, <filename>rpm</filename>, and
<filename>ipk</filename>) based on
<link linkend='var-IMAGE_PKGTYPE'><filename>IMAGE_PKGTYPE</filename></link>.
</para>
<para>
The base class ensures all source and destination directories are
established and then populates the SDK.
After populating the SDK, the <filename>populate_sdk_base</filename>
class constructs two images:
<link linkend='var-SDK_ARCH'><filename>SDK_ARCH</filename></link><filename>-nativesdk</filename>,
which contains the cross-compiler and associated tooling, and the
target, which contains a target root filesystem that is configured for
the SDK usage.
These two images reside in
<link linkend='var-SDK_OUTPUT'><filename>SDK_OUTPUT</filename></link>,
which consists of the following:
<literallayout class='monospaced'>
${SDK_OUTPUT}/<sdk_arch-nativesdk pkgs>
${SDK_OUTPUT}/${SDKTARGETSYSROOT}/<target pkgs>
</literallayout>
</para>
<para>
Finally, the base populate SDK class creates the toolchain
environment setup script, the tarball of the SDK, and the installer.
</para>
<para>
The respective <filename>populate_sdk_deb</filename>,
<filename>populate_sdk_rpm</filename>, and
<filename>populate_sdk_ipk</filename> classes each support the
specific type of SDK.
These classes are inherited by and used with the
<filename>populate_sdk_base</filename> class.
</para>
</section>
<section id='ref-classes-prexport'>
<title><filename>prexport.bbclass</filename></title>
<para>
The <filename>prexport</filename> class provides functionality for
exporting
<link linkend='var-PR'><filename>PR</filename></link> values.
<note>
This class is not intended to be used directly.
Rather, it is enabled when using
"<filename>bitbake-prserv-tool export</filename>".
</note>
</para>
</section>
<section id='ref-classes-primport'>
<title><filename>primport.bbclass</filename></title>
<para>
The <filename>primport</filename> class provides functionality for
importing
<link linkend='var-PR'><filename>PR</filename></link> values.
<note>
This class is not intended to be used directly.
Rather, it is enabled when using
"<filename>bitbake-prserv-tool import</filename>".
</note>
</para>
</section>
<section id='ref-classes-prserv'>
<title><filename>prserv.bbclass</filename></title>
<para>
The <filename>prserv</filename> class provides functionality for
using a
<ulink url='&YOCTO_DOCS_DEV_URL;#working-with-a-pr-service'>PR service</ulink>
in order to automatically manage the incrementing of the
<link linkend='var-PR'><filename>PR</filename></link> variable for
each recipe.
</para>
<para>
This class is enabled by default because it is inherited by the
<link linkend='ref-classes-package'><filename>package</filename></link>
class.
However, the OpenEmbedded build system will not use this variable
unless
<link linkend='var-PRSERV_HOST'><filename>PRSERV_HOST</filename></link>
has been set.
</para>
</section>
<section id='ref-classes-ptest'>
<title><filename>ptest.bbclass</filename></title>
<para>
The <filename>ptest</filename> class provides functionality for
packaging and installing runtime tests for recipes that build software
that provides these tests.
</para>
<para>
This class is intended to be inherited by individual recipes.
However, the class' functionality is largely disabled unless "ptest"
appears in
<link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>.
See the
"<ulink url='&YOCTO_DOCS_DEV_URL;#testing-packages-with-ptest'>Testing Packages With ptest</ulink>"
section in the Yocto Project Development Manual for more information
on ptest.
</para>
</section>
<section id='ref-classes-python-dir'>
<title><filename>python-dir.bbclass</filename></title>
<para>
The <filename>python-dir</filename> class provides the base version,
location, and site package location for Python.
</para>
</section>
<section id='ref-classes-pythonnative'>
<title><filename>pythonnative.bbclass</filename></title>
<para>
The <filename>pythonnative</filename> causes the OpenEmbedded build
system to use the native version of Python, which is built by the
build system.
Normally, the OpenEmbedded build system uses the version of Python
that is built by the build host.
<note>
This class must be inherited by a recipe in order to be used.
</note>
</para>
</section>
<section id='ref-classes-qemu'>
<title><filename>qemu.bbclass</filename></title>
<para>
The <filename>qemu</filename> class provides functionality for recipes
that either need QEMU or test for the existence of QEMU.
Typically, this class is used to run programs for a target system on
the build host using QEMU's application emulation mode.
</para>
</section>
<section id='ref-classes-qmake*'>
<title><filename>qmake*.bbclass</filename></title>
<para>
This family of classes consists of the following:
<itemizedlist>
<listitem><para><emphasis><filename>qmake_base</filename>:</emphasis>
Provides base functionality for all versions of
<filename>qmake</filename>.</para></listitem>
<listitem><para><emphasis><filename>qmake2</filename>:</emphasis>
Extends base functionality for <filename>qmake</filename> 2.x as
used by Qt 4.x.</para></listitem>
</itemizedlist>
</para>
<para>
The <filename>qmake*</filename> family of classes support recipes that
need to build software that uses Qt's <filename>qmake</filename>
build system.
</para>
<para>
If you need to set any configuration variables or pass any options to
<filename>qmake</filename>, you can add these to the
<link linkend='var-EXTRA_QMAKEVARS_PRE'><filename>EXTRA_QMAKEVARS_PRE</filename></link>
or
<link linkend='var-EXTRA_QMAKEVARS_POST'><filename>EXTRA_QMAKEVARS_POST</filename></link>
variables, depending on whether the arguments need to be before or
after the <filename>.pro</filename> file list on the command line,
respectively.
</para>
<para>
By default, all <filename>.pro</filename> files are built.
If you want to specify your own subset of <filename>.pro</filename>
files to be built, specify them in the
<link linkend='var-QMAKE_PROFILES'><filename>QMAKE_PROFILES</filename></link>
variable.
</para>
</section>
<section id='ref-classes-qt4*'>
<title><filename>qt4*.bbclass</filename></title>
<para>
This family of classes consists of the following:
<itemizedlist>
<listitem><para><emphasis><filename>qt4e</filename>:</emphasis>
Supports building against Qt/Embedded, which uses the
framebuffer for graphical output.</para></listitem>
<listitem><para><emphasis><filename>qt4x11</filename>:</emphasis>
Supports building against Qt/X11.</para></listitem>
</itemizedlist>
</para>
<para>
These classes support recipes that need to build software that uses
the Qt development framework version 4.x.
The classes inherit the
<link linkend='ref-classes-qmake*'><filename>qmake2</filename></link>
class.
</para>
</section>
<section id='ref-classes-relocatable'>
<title><filename>relocatable.bbclass</filename></title>
<para>
The <filename>relocatable</filename> class enables relocation of
binaries when they are installed into the sysroot.
</para>
<para>
This class makes use of the
<link linkend='ref-classes-chrpath'><filename>chrpath</filename></link>
class and is used by both the
<link linkend='ref-classes-cross'><filename>cross</filename></link>
and
<link linkend='ref-classes-native'><filename>native</filename></link>
classes.
</para>
</section>
<section id='ref-classes-scons'>
<title><filename>scons.bbclass</filename></title>
<para>
The <filename>scons</filename> class supports recipes that need to
build software that uses the SCons build system.
You can use the
<link linkend='var-EXTRA_OESCONS'><filename>EXTRA_OESCONS</filename></link>
variable to specify additional configuration options you want to pass
SCons command line.
</para>
</section>
<section id='ref-classes-sdl'>
<title><filename>sdl.bbclass</filename></title>
<para>
The <filename>sdl</filename> class supports recipes that need to build
software that uses the Simple DirectMedia Layer (SDL) library.
</para>
</section>
<section id='ref-classes-setuptools'>
<title><filename>setuptools.bbclass</filename></title>
<para>
The <filename>setuptools</filename> class supports extensions that use
setuptools-based build systems.
If your recipe uses these build systems, the recipe needs to
inherit the <filename>setuptools</filename> class.
</para>
</section>
<section id='ref-classes-packagegroup'>
<title>Package Groups - <filename>packagegroup.bbclass</filename></title>
<para>
This class sets default values appropriate for package group recipes (e.g.
<filename><link linkend='var-PACKAGES'>PACKAGES</link></filename>,
<filename><link linkend='var-PACKAGE_ARCH'>PACKAGE_ARCH</link></filename>,
<filename><link linkend='var-ALLOW_EMPTY'>ALLOW_EMPTY</link></filename>,
and so forth).
It is highly recommended that all package group recipes inherit this class.
</para>
<para>
For information on how to use this class, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#usingpoky-extend-customimage-customtasks'>Customizing Images Using Custom Package Groups</ulink>"
section in the Yocto Project Development Manual.
</para>
<para>
Previously, this class was named <filename>task.bbclass</filename>.
</para>
</section>
<section id='ref-classes-package'>
<title><filename>package.bbclass</filename></title>
<para>
The packaging class (<filename>package</filename>) supports generating
packages from a build's output.
The core generic functionality is in the
<filename>package.bbclass</filename>.
The code specific to particular package types resides in these
package-specific classes:
<link linkend='ref-classes-package_deb'><filename>package_deb</filename></link>,
<link linkend='ref-classes-package_rpm'><filename>package_rpm</filename></link>,
<link linkend='ref-classes-package_ipk'><filename>package_ipk</filename></link>,
and
<link linkend='ref-classes-package_tar'><filename>package_tar</filename></link>.
</para>
<para>
You can control the list of resulting package formats by using the
<filename><link linkend='var-PACKAGE_CLASSES'>PACKAGE_CLASSES</link></filename>
variable defined in your <filename>conf/local.conf</filename>
configuration file, which is located in the
<ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
When defining the variable, you can specify one or more package types.
Since images are generated from packages, a packaging class is
needed to enable image generation.
The first class listed in this variable is used for image generation.
</para>
<para>
If you take the optional step to set up a repository (package feed)
on the development host that can be used by Smart, you can
install packages from the feed while you are running the image
on the target (i.e. runtime installation of packages).
For more information, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#using-runtime-package-management'>Using Runtime Package Management</ulink>"
section in the Yocto Project Development Manual.
</para>
<para>
The package-specific class you choose can affect build-time performance
and has space ramifications.
In general, building a package with IPK takes about thirty percent less
time as compared to using RPM to build the same or similar package.
This comparison takes into account a complete build of the package with
all dependencies previously built.
The reason for this discrepancy is because the RPM package manager
creates and processes more
<ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink> than the
IPK package manager.
Consequently, you might consider setting
<filename>PACKAGE_CLASSES</filename> to "package_ipk" if you are
building smaller systems.
</para>
<para>
Before making your package manager decision, however, you should
consider some further things about using RPM:
<itemizedlist>
<listitem><para>
RPM starts to provide more abilities than IPK due to
the fact that it processes more Metadata.
For example, this information includes individual file types,
file checksum generation and evaluation on install, sparse file
support, conflict detection and resolution for Multilib systems,
ACID style upgrade, and repackaging abilities for rollbacks.
</para></listitem>
<listitem><para>
For smaller systems, the extra space used for the Berkley
Database and the amount of metadata when using RPM can affect
your ability to perform on-device upgrades.
</para></listitem>
</itemizedlist>
</para>
<para>
You can find additional information on the effects of the package
class at these two Yocto Project mailing list links:
<itemizedlist>
<listitem><para><ulink url='&YOCTO_LISTS_URL;/pipermail/poky/2011-May/006362.html'>
https://lists.yoctoproject.org/pipermail/poky/2011-May/006362.html</ulink></para></listitem>
<listitem><para><ulink url='&YOCTO_LISTS_URL;/pipermail/poky/2011-May/006363.html'>
https://lists.yoctoproject.org/pipermail/poky/2011-May/006363.html</ulink></para></listitem>
</itemizedlist>
</para>
</section>
<section id='ref-classes-package_deb'>
<title><filename>package_deb.bbclass</filename></title>
<para>
The Debian package manager (<filename>package_deb</filename>) class
provides support for creating packages that use the
<filename>.deb</filename> file format.
The class ensures the packages are written out to the
<filename>${</filename><link linkend='var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></link><filename>}/deb</filename>
directory in a <filename>.deb</filename> file format.
<note>
This package inherits the
<link linkend='ref-classes-package'><filename>package</filename></link>
class.
</note>
</para>
</section>
<section id='ref-classes-package_rpm'>
<title><filename>package_rpm.bbclass</filename></title>
<para>
The RPM package manager (<filename>package_deb</filename>) class
provides support for creating packages that use the
<filename>.rpm</filename> file format.
The class ensures the packages are written out to the
<filename>${</filename><link linkend='var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></link><filename>}/rpm</filename>
directory in a <filename>.rpm</filename> file format.
<note>
This package inherits the
<link linkend='ref-classes-package'><filename>package</filename></link>
class.
</note>
</para>
</section>
<section id='ref-classes-package_ipk'>
<title><filename>package_ipk.bbclass</filename></title>
<para>
The Itsy package manager (<filename>package_ipk</filename>) class
provides support for creating packages that use the
<filename>.ipk</filename> file format.
The class ensures the packages are written out to the
<filename>${</filename><link linkend='var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></link><filename>}/ipk</filename>
directory in a <filename>.ipk</filename> file format.
<note>
This package inherits the
<link linkend='ref-classes-package'><filename>package</filename></link>
class.
</note>
</para>
</section>
<section id='ref-classes-sip'>
<title><filename>sip.bbclass</filename></title>
<para>
The <filename>sip</filename> class
supports recipes that build or package SIP-based Python bindings.
</para>
</section>
<section id='ref-classes-siteconfig'>
<title><filename>siteconfig.bbclass</filename></title>
<para>
The <filename>siteconfig</filename> class
provides functionality for handling site configuration.
The class is used by the
<link linkend='ref-classes-autotools'><filename>autotools</filename></link>
class to accelerate the <filename>do_configure</filename> task.
</para>
</section>
<section id='ref-classes-spdx'>
<title><filename>spdx.bbclass</filename></title>
<para>
The <filename>spdx</filename> class integrates real-time license
scanning, generation of SPDX standard output, and verification
of license information during the build.
<note>
This class is currently at the prototype stage in the 1.5
release.
</note>
</para>
</section>
<section id='ref-classes-sstate'>
<title><filename>sstate.bbclass</filename></title>
<para>
The <filename>sstate</filename> class provides support for Shared
State (sstate).
By default, the class is enabled through the
<link linkend='var-INHERIT_DISTRO'><filename>INHERIT_DISTRO</filename></link>
variable's default value.
</para>
<para>
For more information on sstate, see the
"<link linkend='shared-state-cache'>Shared State Cache</link>"
section.
</para>
</section>
<section id='ref-classes-staging'>
<title><filename>staging.bbclass</filename></title>
<para>
The <filename>staging</filename> class provides support for staging
files into the sysroot during the
<filename>do_populate_sysroot</filename> task.
The class is enabled by default because it is inherited by the
<link linkend='ref-classes-base'><filename>base</filename></link>
class.
</para>
</section>
<section id='ref-classes-syslinux'>
<title><filename>syslinux.bbclass</filename></title>
<para>
The <filename>syslinux</filename> class provides syslinux-specific
functions for building bootable images.
</para>
<para>
The class supports the following variables:
<itemizedlist>
<listitem><para><emphasis><link linkend='var-INITRD'><filename>INITRD</filename></link>:</emphasis>
Indicates a filesystem image to use as an initial RAM disk
(initrd).
This variable is optional.</para></listitem>
<listitem><para><emphasis><link linkend='var-ROOTFS'><filename>ROOTFS</filename></link>:</emphasis>
Indicates a filesystem image to include as the root filesystem.
This variable is optional.</para></listitem>
<listitem><para><emphasis><link linkend='var-AUTO_SYSLINUXMENU'><filename>AUTO_SYSLINUXMENU</filename></link>:</emphasis>
Enables creating an automatic menu when set to "1".
</para></listitem>
<listitem><para><emphasis><link linkend='var-LABELS'><filename>LABELS</filename></link>:</emphasis>
Lists targets for automatic configuration.
</para></listitem>
<listitem><para><emphasis><link linkend='var-APPEND'><filename>APPEND</filename></link>:</emphasis>
Lists append string overrides for each label.
</para></listitem>
<listitem><para><emphasis><link linkend='var-SYSLINUX_OPTS'><filename>SYSLINUX_OPTS</filename></link>:</emphasis>
Lists additional options to add to the syslinux file.
Semicolon characters separate multiple options.
</para></listitem>
<listitem><para><emphasis><link linkend='var-SYSLINUX_SPLASH'><filename>SYSLINUX_SPLASH</filename></link>:</emphasis>
Lists a background for the VGA boot menu when you are using the
boot menu.</para></listitem>
<listitem><para><emphasis><link linkend='var-SYSLINUX_DEFAULT_CONSOLE'><filename>SYSLINUX_DEFAULT_CONSOLE</filename></link>:</emphasis>
Set to "console=ttyX" to change kernel boot default console.
</para></listitem>
<listitem><para><emphasis><link linkend='var-SYSLINUX_SERIAL'><filename>SYSLINUX_SERIAL</filename></link>:</emphasis>
Sets an alternate serial port.
Or, turns off serial when the variable is set with an
empty string.</para></listitem>
<listitem><para><emphasis><link linkend='var-SYSLINUX_SERIAL_TTY'><filename>SYSLINUX_SERIAL_TTY</filename></link>:</emphasis>
Sets an alternate "console=tty..." kernel boot argument.
</para></listitem>
</itemizedlist>
</para>
</section>
<section id='ref-classes-systemd'>
<title><filename>systemd.bbclass</filename></title>
<para>
The <filename>systemd</filename> class provides support for recipes
that install <filename>systemd</filename> unit files.
</para>
<para>
The functionality for this class is disabled unless you have "systemd"
in
<link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>.
</para>
<para>
Under this class, unit files are installed into
<filename>${</filename><link linkend='var-D'><filename>D</filename></link><filename>}${systemd_unitdir}/system</filename>
during the <filename>do_install</filename> task.
If the unit files being installed go into packages other than the
main package, you need to set
<link linkend='var-SYSTEMD_PACKAGES'><filename>SYSTEMD_PACKAGES</filename></link>
in your recipe to identify the packages in which the files will be
installed.
</para>
<para>
You should set
<link linkend='var-SYSTEMD_SERVICE'><filename>SYSTEMD_SERVICE</filename></link>
to the name of the service file.
You should also use a package name override to indicate the package
to which the value applies.
If the value applies to the recipe's main package, use
<filename>${</filename><link linkend='var-PN'><filename>PN</filename></link><filename>}</filename>.
Here is an example from the connman recipe:
<literallayout class='monospaced'>
SYSTEMD_SERVICE_${PN} = "connman.service"
</literallayout>
Services are set up to start on boot automatically unless
you have set
<link linkend='var-SYSTEMD_AUTO_ENABLE'><filename>SYSTEMD_AUTO_ENABLE</filename></link>
to "disable".
</para>
<para>
For more information on <filename>systemd</filename>, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#selecting-an-initialization-manager'>Selecting an Initialization Manager</ulink>"
section in the Yocto Project Development Manual.
</para>
</section>
<section id='ref-classes-package_tar'>
<title><filename>package_tar.bbclass</filename></title>
<para>
The consolidated Unix archive file (<filename>package_tar</filename>)
class provides support for creating packages that use the
<filename>.tar</filename> file format.
The class ensures the packages are written out to the
<filename>${</filename><link linkend='var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></link><filename>}/tar</filename>
directory in a <filename>.tar</filename> file format.
<note>
This package inherits the
<link linkend='ref-classes-package'><filename>package</filename></link>
class.
</note>
</para>
</section>
<section id='ref-classes-rootfs*'>
<title><filename>rootfs*.bbclass</filename></title>
<para>
These classes add support for creating images in several formats.
First, the root filesystem is created from packages using
one of the <filename>rootfs_*.bbclass</filename>
files (depending on the package format used) and then the image is created.
<itemizedlist>
<listitem><para>The
<filename><link linkend='var-IMAGE_FSTYPES'>IMAGE_FSTYPES</link></filename>
variable controls the types of images to generate.
</para></listitem>
<listitem><para>The
<filename><link linkend='var-IMAGE_INSTALL'>IMAGE_INSTALL</link></filename>
variable controls the list of packages to install into the
image.</para></listitem>
</itemizedlist>
</para>
</section>
<section id='ref-classes-sanity'>
<title>Host System Sanity Checks - <filename>sanity.bbclass</filename></title>
<para>
This class checks to see if prerequisite software is present on the host system
so that users can be notified of potential problems that might affect their build.
The class also performs basic user configuration checks from
the <filename>local.conf</filename> configuration file to
prevent common mistakes that cause build failures.
Distribution policy usually determines whether to include this class.
</para>
</section>
<section id='ref-classes-rm-work'>
<title>Removing Work Files During the Build - <filename>rm_work.bbclass</filename></title>
<para>
The OpenEmbedded build system can use a substantial amount of disk
space during the build process.
A portion of this space is the work files under the
<filename>${TMPDIR}/work</filename> directory for each recipe.
Once the build system generates the packages for a recipe, the work
files for that recipe are no longer needed.
However, by default, the build system preserves these files
for inspection and possible debugging purposes.
If you would rather have these files deleted to save disk space
as the build progresses, you can enable <filename>rm_work</filename>
by adding the following to your <filename>local.conf</filename> file,
which is found in the
<ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
<literallayout class='monospaced'>
INHERIT += "rm_work"
</literallayout>
If you are modifying and building source code out of the work directory
for a recipe, enabling <filename>rm_work</filename> will potentially
result in your changes to the source being lost.
To exclude some recipes from having their work directories deleted by
<filename>rm_work</filename>, you can add the names of the recipe or
recipes you are working on to the <filename>RM_WORK_EXCLUDE</filename>
variable, which can also be set in your <filename>local.conf</filename>
file.
Here is an example:
<literallayout class='monospaced'>
RM_WORK_EXCLUDE += "busybox eglibc"
</literallayout>
</para>
</section>
<section id='ref-classes-siteinfo'>
<title>Autotools Configuration Data Cache - <filename>siteinfo.bbclass</filename></title>
<para>
Autotools can require tests that must execute on the target hardware.
Since this is not possible in general when cross compiling, site information is
used to provide cached test results so these tests can be skipped over but
still make the correct values available.
The <filename><link linkend='structure-meta-site'>meta/site directory</link></filename>
contains test results sorted into different categories such as architecture, endianness, and
the <filename>libc</filename> used.
Site information provides a list of files containing data relevant to
the current build in the
<filename><link linkend='var-CONFIG_SITE'>CONFIG_SITE</link></filename> variable
that Autotools automatically picks up.
</para>
<para>
The class also provides variables like
<filename><link linkend='var-SITEINFO_ENDIANNESS'>SITEINFO_ENDIANNESS</link></filename>
and <filename><link linkend='var-SITEINFO_BITS'>SITEINFO_BITS</link></filename>
that can be used elsewhere in the metadata.
</para>
<para>
Because this class is included from <filename>base.bbclass</filename>, it is always active.
</para>
</section>
<section id='ref-classes-terminal'>
<title><filename>terminal.bbclass</filename></title>
<para>
The <filename>terminal</filename> class provides support for starting
a terminal session.
The
<link linkend='var-OE_TERMINAL'><filename>OE_TERMINAL</filename></link>
variable controls which terminal emulator is used for the session.
</para>
<para>
You can use this class anywhere a separate terminal session needs to
be started.
To use the class, include the
<link linkend='ref-classes-patch'><filename>patch</filename></link>
class if
<link linkend='var-PATCHRESOLVE'><filename>PATCHRESOLVE</filename></link>
is set to "user", include the
<link linkend='ref-classes-cml1'><filename>cml1</filename></link>
class, and include the
<link linkend='ref-classes-devshell'><filename>devshell</filename></link>
class.
</para>
</section>
<section id='ref-classes-tinderclient'>
<title><filename>tinderclient.bbclass</filename></title>
<para>
The <filename>tinderclient</filename> class submits build results to
an external Tinderbox instance.
<note>
This class is currently unmaintained.
</note>
</para>
</section>
<section id='ref-classes-toaster'>
<title><filename>toaster.bbclass</filename></title>
<para>
The <filename>toaster</filename> class collects information about
packages and images and sends them as events that the BitBake
user interface can receive.
The class is enabled when the Toaster user interface is running.
</para>
<para>
This class is not intended to be used directly.
</para>
</section>
<section id='ref-classes-toolchain-scripts'>
<title><filename>toolchain-scripts.bbclass</filename></title>
<para>
The <filename>toolchain-scripts</filename> class provides the scripts
used for setting up the environment for installed SDKs.
</para>
</section>
<section id='ref-classes-typecheck'>
<title><filename>typecheck.bbclass</filename></title>
<para>
The <filename>typecheck</filename> class provides support for
validating the values of variables set at the configuration level
against their defined types.
The OpenEmbedded build system allows you to define the type of a
variable using the "type" varflag.
Here is an example:
<literallayout class='monospaced'>
IMAGE_FEATURES[type] = "list"
</literallayout>
</para>
</section>
<section id='ref-classes-uboot-config'>
<title><filename>uboot-config.bbclass</filename></title>
<para>
The <filename>uboot-config</filename> class provides support for
U-Boot configuration for a machine.
Specify the machine in your recipe as follows:
<literallayout class='monospaced'>
UBOOT_CONFIG ??= <default>
UBOOT_CONFIG[foo] = "config,images"
</literallayout>
You can also specify the machine using this method:
<literallayout class='monospaced'>
UBOOT_MACHINE = "config"
</literallayout>
See the
<link linkend='var-UBOOT_CONFIG'><filename>UBOOT_CONFIG</filename></link>
and
<link linkend='var-UBOOT_MACHINE'><filename>UBOOT_MACHINE</filename></link>
variables for additional information.
</para>
</section>
<section id='ref-classes-useradd'>
<title>Adding Users - <filename>useradd.bbclass</filename></title>
<para>
If you have packages that install files that are owned by custom users or groups,
you can use this class to specify those packages and associate the users and groups
with those packages.
The <filename>meta-skeleton/recipes-skeleton/useradd/useradd-example.bb</filename>
recipe in the <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
provides a simple example that shows how to add three
users and groups to two packages.
See the <filename>useradd-example.bb</filename> for more information on how to
use this class.
</para>
</section>
<section id='ref-classes-utility-tasks'>
<title><filename>utility-tasks.bbclass</filename></title>
<para>
The <filename>utility-tasks</filename> class provides support for
various "utility" type tasks that are applicable to all recipes,
such as <filename>do_clean</filename> and
<filename>do_listtasks</filename>.
</para>
<para>
This class is enabled by default because it is inherited by
the
<link linkend='ref-classes-base'><filename>base</filename></link>
class.
</para>
</section>
<section id='ref-classes-utils'>
<title><filename>utils.bbclass</filename></title>
<para>
The <filename>utils</filename> class provides some useful Python
functions that are typically used in inline Python expressions
(e.g. <filename>${@...}</filename>).
One example use is for <filename>base_contains()</filename>.
</para>
<para>
This class is enabled by default because it is inherited by the
<link linkend='ref-classes-base'><filename>base</filename></link>
class.
</para>
</section>
<section id='ref-classes-vala'>
<title><filename>vala.bbclass</filename></title>
<para>
The <filename>vala</filename> class supports recipes that need to
build software written using the Vala programming language.
</para>
</section>
<section id='ref-classes-waf'>
<title><filename>waf.bbclass</filename></title>
<para>
The <filename>waf</filename> class supports recipes that need to build
software that uses the Waf build system.
You can use the
<link linkend='var-EXTRA_OECONF'><filename>EXTRA_OECONF</filename></link>
variable to specify additional configuration options to be passed on
the Waf command line.
</para>
</section>
<section id='ref-classes-externalsrc'>
<title><filename>externalsrc.bbclass</filename></title>
<para>
You can use this class to build software from source code that is
external to the OpenEmbedded build system.
Building software from an external source tree means that the build
system's normal fetch, unpack, and patch process is not used.
</para>
<para>
By default, the OpenEmbedded build system uses the
<link linkend='var-S'><filename>S</filename></link> and
<link linkend='var-B'><filename>B</filename></link> variables to
locate unpacked recipe source code and to build it, respectively.
When your recipe inherits <filename>externalsrc.bbclass</filename>,
you use the
<link linkend='var-EXTERNALSRC'><filename>EXTERNALSRC</filename></link>
and
<link linkend='var-EXTERNALSRC_BUILD'><filename>EXTERNALSRC_BUILD</filename></link>
variables to ultimately define <filename>S</filename> and
<filename>B</filename>.
</para>
<para>
By default, this class expects the source code to support recipe builds
that use the <link linkend='var-B'><filename>B</filename></link>
variable to point to the directory in which the OpenEmbedded build
system places the generated objects built from the recipes.
By default, the <filename>B</filename> directory is set to the
following, which is separate from the source directory
(<filename>S</filename>):
<literallayout class='monospaced'>
${WORKDIR}/${BPN}/{PV}/
</literallayout>
See the glossary entries for the
<link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>,
<link linkend='var-BPN'><filename>BPN</filename></link>,
<link linkend='var-PV'><filename>PV</filename></link>,
</para>
<para>
For more information on
<filename>externalsrc.bbclass</filename>, see the comments in
<filename>meta/classes/externalsrc.bbclass</filename> in the
<ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
For information on how to use <filename>externalsrc.bbclass</filename>,
see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#building-software-from-an-external-source'>Building Software from an External Source</ulink>"
section in the Yocto Project Development Manual.
</para>
</section>
<section id='ref-classes-testimage'>
<title><filename>testimage.bbclass</filename></title>
<para>
You can use this class to enable running a series of automated tests
for images.
The class handles loading the tests and starting the image.
<note>
Currently, there is only support for running these tests
under QEMU.
</note>
</para>
<para>
To use the class, you need to perform steps to set up the
environment.
The tests are commands that run on the target system over
<filename>ssh</filename>.
they are written in Python and make use of the
<filename>unittest</filename> module.
</para>
<para>
For information on how to enable, run, and create new tests, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#performing-automated-runtime-testing'>Performing Automated Runtime Testing</ulink>"
section.
</para>
</section>
<section id='ref-classes-update-alternatives'>
<title>Alternatives - <filename>update-alternatives.bbclass</filename></title>
<para>
This class helps the alternatives system when multiple sources provide
the same command.
This situation occurs when several programs that have the same or
similar function are installed with the same name.
For example, the <filename>ar</filename> command is available from the
<filename>busybox</filename>, <filename>binutils</filename> and
<filename>elfutils</filename> packages.
The <filename>update-alternatives.bbclass</filename> class handles
renaming the binaries so that multiple packages can be installed
without conflicts.
The <filename>ar</filename> command still works regardless of which
packages are installed or subsequently removed.
The class renames the conflicting binary in each package and symlinks
the highest priority binary during installation or removal of packages.
</para>
<para>
To use this class, you need to define a number of variables:
<itemizedlist>
<listitem><para><link linkend='var-ALTERNATIVE'><filename>ALTERNATIVE</filename></link>
</para></listitem>
<listitem><para><link linkend='var-ALTERNATIVE_LINK_NAME'><filename>ALTERNATIVE_LINK_NAME</filename></link>
</para></listitem>
<listitem><para><link linkend='var-ALTERNATIVE_TARGET'><filename>ALTERNATIVE_TARGET</filename></link>
</para></listitem>
<listitem><para><link linkend='var-ALTERNATIVE_PRIORITY'><filename>ALTERNATIVE_PRIORITY</filename></link>
</para></listitem>
</itemizedlist>
These variables list alternative commands needed by a package,
provide pathnames for links, default links for targets, and
so forth.
For details on how to use this class, see the comments in the
<ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/poky/tree/meta/classes/update-alternatives.bbclass'><filename>update-alternatives.bbclass</filename></ulink>.
</para>
<note>
You can use the <filename>update-alternatives</filename> command
directly in your recipes.
However, this class simplifies things in most cases.
</note>
</section>
<section id='ref-classes-update-rc.d'>
<title>Initscripts - <filename>update-rc.d.bbclass</filename></title>
<para>
This class uses <filename>update-rc.d</filename> to safely install an
initialization script on behalf of the package.
The OpenEmbedded build system takes care of details such as making sure the script is stopped before
a package is removed and started when the package is installed.
Three variables control this class:
<filename><link linkend='var-INITSCRIPT_PACKAGES'>INITSCRIPT_PACKAGES</link></filename>,
<filename><link linkend='var-INITSCRIPT_NAME'>INITSCRIPT_NAME</link></filename> and
<filename><link linkend='var-INITSCRIPT_PARAMS'>INITSCRIPT_PARAMS</link></filename>.
See the variable links for details.
</para>
</section>
<section id='ref-classes-others'>
<title>Other Classes</title>
<para>
Thus far, this chapter has discussed only the most useful and important
classes.
However, other classes exist within the <filename>meta/classes</filename> directory
in the <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
You can examine the <filename>.bbclass</filename> files directly for more
information.
</para>
</section>
<!-- Undocumented classes are:
allarch.bbclass
bin_package.bbclass
blacklist.bbclass
bootimg.bbclass
boot-directdisk.bbclass
bugzilla.bbclass
buildhistory.bbclass
buildstats.bbclass
ccache.bbclass
chrpath.bbclass
clutter.bbclass
cmake.bbclass
cml1.bbclass
copyleft_compliance.bbclass
core-image.bbclass
cross.bbclass
cross-canadian.bbclass
crosssdk.bbclass
deploy.bbclass
distrodata.bbclass
distro_features_check.bbclass
dummy.bbclass
extrausers.bbclass
fontcache.bbclass
gconf.bbclass
gettext.bbclass
gnomebase.bbclass
gnome.bbclass
grub-efi.bbclass
gsettings.bbclass
gtk-doc.bbclass
gtk-icon-cache.bbclass
gtk-immodules-cache.bbclass
gzipnative.bbclass
icecc.bbclass
image-empty.bbclass
image-live.bbclass
image-vmdk.bbclass
image-mklibs.bbclass
image-prelink.bbclass
image-swab.bbclass
image_types.bbclass
image_types_uboot.bbclass
insserv.bbclass
kernel-arch.bbclass
kernel-module-split.bbclass
kernel-yocto.bbclass
lib_package.bbclass
linux-kernel-base.bbclass
license.bbclass
logging.bbclass
meta.bbclass
metadata_scm.bbclass
migrate_localcount.bbclass
mime.bbclass
mirrors.bbclass
multilib*.bbclass
native.bbclass
nativesdk.bbclass
oelint.bbclass
own-mirrors.bbclass
packagedata.bbclass
packageinfo.bbclass
patch.bbclass
perlnative.bbclass
pixbufcache.bbclass
pkg_distribute.bbclass
pkg_metainfo.bbclass
populate_sdk*.bbclass
prexport.bbclass
primport.bbclass
prserv.bbclass
ptest.bbclass
python-dir.bbclass
pythonnative.bbclass
qemu.bbclass
qmake*.bbclass
qt4*.bbclass
recipe_sanity.bbclass
relocatable.bbclass
scons.bbclass
sdl.bbclass
setuptools.bbclass
sip.bbclass
siteconfig.bbclass
sourcepkg.bbclass
spdx.bbclass
sstate.bbclass
staging.bbclass
syslinux.bbclass
systemd.bbclass
terminal.bbclass
tinderclient.bbclass
toolchain-scripts.bbclass
typecheck.bbclass
uboot-config.bbclass
utility-tasks.bbclass
utils.bbclass
vala.bbclass
waf.bbclass
-->
</chapter>
<!--
vim: expandtab tw=80 ts=4
-->
|