summaryrefslogtreecommitdiffstats
path: root/documentation/dev-manual/dev-manual-common-tasks.xml
blob: aad8fb7787e10c1880d698b987aec5192bdaf228 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
6301
6302
6303
6304
6305
6306
6307
6308
6309
6310
6311
6312
6313
6314
6315
6316
6317
6318
6319
6320
6321
6322
6323
6324
6325
6326
6327
6328
6329
6330
6331
6332
6333
6334
6335
6336
6337
6338
6339
6340
6341
6342
6343
6344
6345
6346
6347
6348
6349
6350
6351
6352
6353
6354
6355
6356
6357
6358
6359
6360
6361
6362
6363
6364
6365
6366
6367
6368
6369
6370
6371
6372
6373
6374
6375
6376
6377
6378
6379
6380
6381
6382
6383
6384
6385
6386
6387
6388
6389
6390
6391
6392
6393
6394
6395
6396
6397
6398
6399
6400
6401
6402
6403
6404
6405
6406
6407
6408
6409
6410
6411
6412
6413
6414
6415
6416
6417
6418
6419
6420
6421
6422
6423
6424
6425
6426
6427
6428
6429
6430
6431
6432
6433
6434
6435
6436
6437
6438
6439
6440
6441
6442
6443
6444
6445
6446
6447
6448
6449
6450
6451
6452
6453
6454
6455
6456
6457
6458
6459
6460
6461
6462
6463
6464
6465
6466
6467
6468
6469
6470
6471
6472
6473
6474
6475
6476
6477
6478
6479
6480
6481
6482
6483
6484
6485
6486
6487
6488
6489
6490
6491
6492
6493
6494
6495
6496
6497
6498
6499
6500
6501
6502
6503
6504
6505
6506
6507
6508
6509
6510
6511
6512
6513
6514
6515
6516
6517
6518
6519
6520
6521
6522
6523
6524
6525
6526
6527
6528
6529
6530
6531
6532
6533
6534
6535
6536
6537
6538
6539
6540
6541
6542
6543
6544
6545
6546
6547
6548
6549
6550
6551
6552
6553
6554
6555
6556
6557
6558
6559
6560
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
6577
6578
6579
6580
6581
6582
6583
6584
6585
6586
6587
6588
6589
6590
6591
6592
6593
6594
6595
6596
6597
6598
6599
6600
6601
6602
6603
6604
6605
6606
6607
6608
6609
6610
6611
6612
6613
6614
6615
6616
6617
6618
6619
6620
6621
6622
6623
6624
6625
6626
6627
6628
6629
6630
6631
6632
6633
6634
6635
6636
6637
6638
6639
6640
6641
6642
6643
6644
6645
6646
6647
6648
6649
6650
6651
6652
6653
6654
6655
6656
6657
6658
6659
6660
6661
6662
6663
6664
6665
6666
6667
6668
6669
6670
6671
6672
6673
6674
6675
6676
6677
6678
6679
6680
6681
6682
6683
6684
6685
6686
6687
6688
6689
6690
6691
6692
6693
6694
6695
6696
6697
6698
6699
6700
6701
6702
6703
6704
6705
6706
6707
6708
6709
6710
6711
6712
6713
6714
6715
6716
6717
6718
6719
6720
6721
6722
6723
6724
6725
6726
6727
6728
6729
6730
6731
6732
6733
6734
6735
6736
6737
6738
6739
6740
6741
6742
6743
6744
6745
6746
6747
6748
6749
6750
6751
6752
6753
6754
6755
6756
6757
6758
6759
6760
6761
6762
6763
6764
6765
6766
6767
6768
6769
6770
6771
6772
6773
6774
6775
6776
6777
6778
6779
6780
6781
6782
6783
6784
6785
6786
6787
6788
6789
6790
6791
6792
6793
6794
6795
6796
6797
6798
6799
6800
6801
6802
6803
6804
6805
6806
6807
6808
6809
6810
6811
6812
6813
6814
6815
6816
6817
6818
6819
6820
6821
6822
6823
6824
6825
6826
6827
6828
6829
6830
6831
6832
6833
6834
6835
6836
6837
6838
6839
6840
6841
6842
6843
6844
6845
6846
6847
6848
6849
6850
6851
6852
6853
6854
6855
6856
6857
6858
6859
6860
6861
6862
6863
6864
6865
6866
6867
6868
6869
6870
6871
6872
6873
6874
6875
6876
6877
6878
6879
6880
6881
6882
6883
6884
6885
6886
6887
6888
6889
6890
6891
6892
6893
6894
6895
6896
6897
6898
6899
6900
6901
6902
6903
6904
6905
6906
6907
6908
6909
6910
6911
6912
6913
6914
6915
6916
6917
6918
6919
6920
6921
6922
6923
6924
6925
6926
6927
6928
6929
6930
6931
6932
6933
6934
6935
6936
6937
6938
6939
6940
6941
6942
6943
6944
6945
6946
6947
6948
6949
6950
6951
6952
6953
6954
6955
6956
6957
6958
6959
6960
6961
6962
6963
6964
6965
6966
6967
6968
6969
6970
6971
6972
6973
6974
6975
6976
6977
6978
6979
6980
6981
6982
6983
6984
6985
6986
6987
6988
6989
6990
6991
6992
6993
6994
6995
6996
6997
6998
6999
7000
7001
7002
7003
7004
7005
7006
7007
7008
7009
7010
7011
7012
7013
7014
7015
7016
7017
7018
7019
7020
7021
7022
7023
7024
7025
7026
7027
7028
7029
7030
7031
7032
7033
7034
7035
7036
7037
7038
7039
7040
7041
7042
7043
7044
7045
7046
7047
7048
7049
7050
7051
7052
7053
7054
7055
7056
7057
7058
7059
7060
7061
7062
7063
7064
7065
7066
7067
7068
7069
7070
7071
7072
7073
7074
7075
7076
7077
7078
7079
7080
7081
7082
7083
7084
7085
7086
7087
7088
7089
7090
7091
7092
7093
7094
7095
7096
7097
7098
7099
7100
7101
7102
7103
7104
7105
7106
7107
7108
7109
7110
7111
7112
7113
7114
7115
7116
7117
7118
7119
7120
7121
7122
7123
7124
7125
7126
7127
7128
7129
7130
7131
7132
7133
7134
7135
7136
7137
7138
7139
7140
7141
7142
7143
7144
7145
7146
7147
7148
7149
7150
7151
7152
7153
7154
7155
7156
7157
7158
7159
7160
7161
7162
7163
7164
7165
7166
7167
7168
7169
7170
7171
7172
7173
7174
7175
7176
7177
7178
7179
7180
7181
7182
7183
7184
7185
7186
7187
7188
7189
7190
7191
7192
7193
7194
7195
7196
7197
7198
7199
7200
7201
7202
7203
7204
7205
7206
7207
7208
7209
7210
7211
7212
7213
7214
7215
7216
7217
7218
7219
7220
7221
7222
7223
7224
7225
7226
7227
7228
7229
7230
7231
7232
7233
7234
7235
7236
7237
7238
7239
7240
7241
7242
7243
7244
7245
7246
7247
7248
7249
7250
7251
7252
7253
7254
7255
7256
7257
7258
7259
7260
7261
7262
7263
7264
7265
7266
7267
7268
7269
7270
7271
7272
7273
7274
7275
7276
7277
7278
7279
7280
7281
7282
7283
7284
7285
7286
7287
7288
7289
7290
7291
7292
7293
7294
7295
7296
7297
7298
7299
7300
7301
7302
7303
7304
7305
7306
7307
7308
7309
7310
7311
7312
7313
7314
7315
7316
7317
7318
7319
7320
7321
7322
7323
7324
7325
7326
7327
7328
7329
7330
7331
7332
7333
7334
7335
7336
7337
7338
7339
7340
7341
7342
7343
7344
7345
7346
7347
7348
7349
7350
7351
7352
7353
7354
7355
7356
7357
7358
7359
7360
7361
7362
7363
7364
7365
7366
7367
7368
7369
7370
7371
7372
7373
7374
7375
7376
7377
7378
7379
7380
7381
7382
7383
7384
7385
7386
7387
7388
7389
7390
7391
7392
7393
7394
7395
7396
7397
7398
7399
7400
7401
7402
7403
7404
7405
7406
7407
7408
7409
7410
7411
7412
7413
7414
7415
7416
7417
7418
7419
7420
7421
7422
7423
7424
7425
7426
7427
7428
7429
7430
7431
7432
7433
7434
7435
7436
7437
7438
7439
7440
7441
7442
7443
7444
7445
7446
7447
7448
7449
7450
7451
7452
7453
7454
7455
7456
7457
7458
7459
7460
7461
7462
7463
7464
7465
7466
7467
7468
7469
7470
7471
7472
7473
7474
7475
7476
7477
7478
7479
7480
7481
7482
7483
7484
7485
7486
7487
7488
7489
7490
7491
7492
7493
7494
7495
7496
7497
7498
7499
7500
7501
7502
7503
7504
7505
7506
7507
7508
7509
7510
7511
7512
7513
7514
7515
7516
7517
7518
7519
7520
7521
7522
7523
7524
7525
7526
7527
7528
7529
7530
7531
7532
7533
7534
7535
7536
7537
7538
7539
7540
7541
7542
7543
7544
7545
7546
7547
7548
7549
7550
7551
7552
7553
7554
7555
7556
7557
7558
7559
7560
7561
7562
7563
7564
7565
7566
7567
7568
7569
7570
7571
7572
7573
7574
7575
7576
7577
7578
7579
7580
7581
7582
7583
7584
7585
7586
7587
7588
7589
7590
7591
7592
7593
7594
7595
7596
7597
7598
7599
7600
7601
7602
7603
7604
7605
7606
7607
7608
7609
7610
7611
7612
7613
7614
7615
7616
7617
7618
7619
7620
7621
7622
7623
7624
7625
7626
7627
7628
7629
7630
7631
7632
7633
7634
7635
7636
7637
7638
7639
7640
7641
7642
7643
7644
7645
7646
7647
7648
7649
7650
7651
7652
7653
7654
7655
7656
7657
7658
7659
7660
7661
7662
7663
7664
7665
7666
7667
7668
7669
7670
7671
7672
7673
7674
7675
7676
7677
7678
7679
7680
7681
7682
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >

<chapter id='extendpoky'>

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

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

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

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

        <para>
        </para>

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

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

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

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

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

            <para>
                Follow these general steps to create your layer:
                <orderedlist>
                    <listitem><para><emphasis>Check Existing Layers:</emphasis>
                        Before creating a new layer, you should be sure someone
                        has not already created a layer containing the Metadata
                        you need.
                        You can see the
                        <ulink url='http://layers.openembedded.org/layerindex/layers/'><filename>OpenEmbedded Metadata Index</filename></ulink>
                        for a list of layers from the OpenEmbedded community
                        that can be used in the Yocto Project.
                        </para></listitem>
                    <listitem><para><emphasis>Create a Directory:</emphasis>
                        Create the directory for your layer.
                        While not strictly required, prepend the name of the
                        folder with the string <filename>meta-</filename>.
                        For example:
                        <literallayout class='monospaced'>
     meta-mylayer
     meta-GUI_xyz
     meta-mymachine
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Create a Layer Configuration
                       File:</emphasis>
                       Inside your new layer folder, you need to create a
                       <filename>conf/layer.conf</filename> file.
                       It is easiest to take an existing layer configuration
                       file and copy that to your layer's
                       <filename>conf</filename> directory and then modify the
                       file as needed.</para>
                       <para>The
                       <filename>meta-yocto-bsp/conf/layer.conf</filename> file
                       demonstrates the required syntax:
                       <literallayout class='monospaced'>
     # We have a conf and classes directory, add to BBPATH
     BBPATH .= ":${LAYERDIR}"

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

     BBFILE_COLLECTIONS += "yoctobsp"
     BBFILE_PATTERN_yoctobsp = "^${LAYERDIR}/"
     BBFILE_PRIORITY_yoctobsp = "5"
     LAYERVERSION_yoctobsp = "2"
                        </literallayout></para>
                        <para>Here is an explanation of the example:
                        <itemizedlist>
                            <listitem><para>The configuration and
                                classes directory is appended to
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-BBPATH'><filename>BBPATH</filename></ulink>.
                                <note>
                                    All non-distro layers, which include all BSP
                                    layers, are expected to append the layer
                                    directory to the
                                    <filename>BBPATH</filename>.
                                    On the other hand, distro layers, such as
                                    <filename>meta-yocto</filename>, can choose
                                    to enforce their own precedence over
                                    <filename>BBPATH</filename>.
                                    For an example of that syntax, see the
                                    <filename>layer.conf</filename> file for
                                    the <filename>meta-yocto</filename> layer.
                                </note></para></listitem>
                            <listitem><para>The recipes for the layers are
                                appended to
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILES'>BBFILES</ulink></filename>.
                                </para></listitem>
                            <listitem><para>The
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILE_COLLECTIONS'>BBFILE_COLLECTIONS</ulink></filename>
                                variable is then appended with the layer name.
                                </para></listitem>
                            <listitem><para>The
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILE_PATTERN'>BBFILE_PATTERN</ulink></filename>
                                variable is set to a regular expression and is
                                used to match files from
                                <filename>BBFILES</filename> into a particular
                                layer.
                                In this case,
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LAYERDIR'>LAYERDIR</ulink></filename>
                                is used to make <filename>BBFILE_PATTERN</filename> match within the
                                layer's path.</para></listitem>
                            <listitem><para>The
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BBFILE_PRIORITY'>BBFILE_PRIORITY</ulink></filename>
                                variable then assigns a priority to the layer.
                                Applying priorities is useful in situations
                                where the same package might appear in multiple
                                layers and allows you to choose the layer
                                that takes precedence.</para></listitem>
                            <listitem><para>The
                                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LAYERVERSION'>LAYERVERSION</ulink></filename>
                                variable optionally specifies the version of a
                                layer as a single number.</para></listitem>
                        </itemizedlist></para>
                        <para>Note the use of the
                        <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LAYERDIR'>LAYERDIR</ulink></filename>
                        variable, which expands to the directory of the current
                        layer.</para>
                        <para>Through the use of the <filename>BBPATH</filename>
                        variable, BitBake locates class files
                        (<filename>.bbclass</filename>),
                        configuration files, and files that are included
                        with <filename>include</filename> and
                        <filename>require</filename> statements.
                        For these cases, BitBake uses the first file that
                        matches the name found in <filename>BBPATH</filename>.
                        This is similar to the way the <filename>PATH</filename>
                        variable is used for binaries.
                        It is recommended, therefore, that you use unique
                        class and configuration
                        filenames in your custom layer.</para></listitem>
                    <listitem><para><emphasis>Add Content:</emphasis> Depending
                        on the type of layer, add the content.
                        If the layer adds support for a machine, add the machine
                        configuration in a <filename>conf/machine/</filename>
                        file within the layer.
                        If the layer adds distro policy, add the distro
                        configuration in a <filename>conf/distro/</filename>
                        file within the layer.
                        If the layer introduces new recipes, put the recipes
                        you need in <filename>recipes-*</filename>
                        subdirectories within the layer.
                        <note>In order to be compliant with the Yocto Project,
                            a layer must contain a
                            <ulink url='&YOCTO_DOCS_BSP_URL;#bsp-filelayout-readme'>README file.</ulink>
                            </note></para></listitem>
                </orderedlist>
            </para>
        </section>

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

            <para>
                To create layers that are easier to maintain and that will
                not impact builds for other machines, you should consider the
                information in the following sections.
            </para>

            <section id='avoid-overlaying-entire-recipes'>
                <title>Avoid "Overlaying" Entire Recipes</title>

                <para>
                    Avoid "overlaying" entire recipes from other layers in your
                    configuration.
                    In other words, do not copy an entire recipe into your
                    layer and then modify it.
                    Rather, use an append file (<filename>.bbappend</filename>)
                    to override
                    only those parts of the original recipe you need to modify.
                </para>
            </section>

            <section id='avoid-duplicating-include-files'>
                <title>Avoid Duplicating Include Files</title>

                <para>
                    Avoid duplicating include files.
                    Use append files (<filename>.bbappend</filename>)
                    for each recipe
                    that uses an include file.
                    Or, if you are introducing a new recipe that requires
                    the included file, use the path relative to the original
                    layer directory to refer to the file.
                    For example, use
                    <filename>require recipes-core/somepackage/somefile.inc</filename>
                    instead of <filename>require somefile.inc</filename>.
                    If you're finding you have to overlay the include file,
                    it could indicate a deficiency in the include file in
                    the layer to which it originally belongs.
                    If this is the case, you need to address that deficiency
                    instead of overlaying the include file.
                </para>

                <para>
                    For example, consider how support plug-ins for the Qt 4
                    database are configured.
                    The Source Directory does not have MySQL or PostgreSQL.
                    However, OpenEmbedded's layer <filename>meta-oe</filename>
                    does.
                    Consequently, <filename>meta-oe</filename> uses
                    append files to modify the
                    <filename>QT_SQL_DRIVER_FLAGS</filename> variable to
                    enable the appropriate plug-ins.
                    This variable was added to the <filename>qt4.inc</filename>
                    include file in the Source Directory specifically to allow
                    the <filename>meta-oe</filename> layer to be able to control
                    which plug-ins are built.
                </para>
            </section>

            <section id='structure-your-layers'>
                <title>Structure Your Layers</title>

                <para>
                    Proper use of overrides within append files and placement
                    of machine-specific files within your layer can ensure that
                    a build is not using the wrong Metadata and negatively
                    impacting a build for a different machine.
                    Following are some examples:
                    <itemizedlist>
                        <listitem><para><emphasis>Modifying Variables to Support
                            a Different Machine:</emphasis>
                            Suppose you have a layer named
                            <filename>meta-one</filename> that adds support
                            for building machine "one".
                            To do so, you use an append file named
                            <filename>base-files.bbappend</filename> and
                            create a dependency on "foo" by altering the
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
                            variable:
                            <literallayout class='monospaced'>
     DEPENDS = "foo"
                            </literallayout>
                            The dependency is created during any build that
                            includes the layer
                            <filename>meta-one</filename>.
                            However, you might not want this dependency
                            for all machines.
                            For example, suppose you are building for
                            machine "two" but your
                            <filename>bblayers.conf</filename> file has the
                            <filename>meta-one</filename> layer included.
                            During the build, the
                            <filename>base-files</filename> for machine
                            "two" will also have the dependency on
                            <filename>foo</filename>.</para>
                            <para>To make sure your changes apply only when
                            building machine "one", use a machine override
                            with the <filename>DEPENDS</filename> statement:
                            <literallayout class='monospaced'>
     DEPENDS_one = "foo"
                            </literallayout>
                            You should follow the same strategy when using
                            <filename>_append</filename> and
                            <filename>_prepend</filename> operations:
                            <literallayout class='monospaced'>
     DEPENDS_append_one = " foo"
     DEPENDS_prepend_one = "foo "
                            </literallayout>
                            <note>
                                Avoiding "+=" and "=+" and using
                                machine-specific
                                <filename>_append</filename>
                                and <filename>_prepend</filename> operations
                                is recommended as well.
                            </note></para></listitem>
                        <listitem><para><emphasis>Place Machine-Specific Files
                            in Machine-Specific Locations:</emphasis>
                            When you have a base recipe, such as
                            <filename>base-files.bb</filename>, that
                            contains a
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                            statement to a file, you can use an append file
                            to cause the build to use your own version of
                            the file.
                            For example, an append file in your layer at
                            <filename>meta-one/recipes-core/base-files/base-files.bbappend</filename>
                            could extend
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESPATH'><filename>FILESPATH</filename></ulink>
                            using
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></ulink>
                            as follows:
                            <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/${BPN}:"
                            </literallayout>
                            The build for machine "one" will pick up your
                            machine-specific file as long as you have the
                            file in
                            <filename>meta-one/recipes-core/base-files/base-files/</filename>.
                            However, if you are building for a different
                            machine and the
                            <filename>bblayers.conf</filename> file includes
                            the <filename>meta-one</filename> layer and
                            the location of your machine-specific file is
                            the first location where that file is found
                            according to <filename>FILESPATH</filename>,
                            builds for all machines will also use that
                            machine-specific file.</para>
                            <para>You can make sure that a machine-specific
                            file is used for a particular machine by putting
                            the file in a subdirectory specific to the
                            machine.
                            For example, rather than placing the file in
                            <filename>meta-one/recipes-core/base-files/base-files/</filename>
                            as shown above, put it in
                            <filename>meta-one/recipes-core/base-files/base-files/one/</filename>.
                            Not only does this make sure the file is used
                            only when building for machine "one", but the
                            build process locates the file more quickly.</para>
                            <para>In summary, you need to place all files
                            referenced from <filename>SRC_URI</filename>
                            in a machine-specific subdirectory within the
                            layer in order to restrict those files to
                            machine-specific builds.</para></listitem>
                    </itemizedlist>
                </para>
            </section>

            <section id='other-recommendations'>
                <title>Other Recommendations</title>

                <para>
                    We also recommend the following:
                    <itemizedlist>
                        <listitem><para>Store custom layers in a Git repository
                            that uses the
                            <filename>meta-&lt;layer_name&gt;</filename> format.
                            </para></listitem>
                        <listitem><para>Clone the repository alongside other
                            <filename>meta</filename> directories in the
                            <link linkend='source-directory'>Source Directory</link>.
                            </para></listitem>
                     </itemizedlist>
                     Following these recommendations keeps your Source Directory and
                     its configuration entirely inside the Yocto Project's core
                     base.
                </para>
            </section>
        </section>

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

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

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

     BBLAYERS ?= " \
       $HOME/poky/meta \
       $HOME/poky/meta-yocto \
       $HOME/poky/meta-yocto-bsp \
       $HOME/poky/meta-mylayer \
       "

     BBLAYERS_NON_REMOVABLE ?= " \
       $HOME/poky/meta \
       $HOME/poky/meta-yocto \
       "
                </literallayout>
            </para>

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

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

            <para>
                Recipes used to append Metadata to other recipes are called
                BitBake append files.
                BitBake append files use the <filename>.bbappend</filename> file
                type suffix, while the corresponding recipes to which Metadata
                is being appended use the <filename>.bb</filename> file type
                suffix.
            </para>

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

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

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

            <para>
                As an example, consider the main formfactor recipe and a
                corresponding formfactor append file both from the
                <link linkend='source-directory'>Source Directory</link>.
                Here is the main formfactor recipe, which is named
                <filename>formfactor_0.0.bb</filename> and located in the
                "meta" layer at
                <filename>meta/recipes-bsp/formfactor</filename>:
                <literallayout class='monospaced'>
     SUMMARY = "Device formfactor information"
     SECTION = "base"
     LICENSE = "MIT"
     LIC_FILES_CHKSUM = "file://${COREBASE}/LICENSE;md5=4d92cd373abda3937c2bc47fbc49d690 \
                    file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
     PR = "r44"

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

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

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

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

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

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

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

                    <para>
                        Also, not all append files add extra files.
                        Many append files simply exist to add build options
                        (e.g. <filename>systemd</filename>).
                        For these cases, it is not necessary to use the
                        "_prepend" part of the statement.
                    </para>
                </note>
            </para>
        </section>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

     BBLAYERS_NON_REMOVABLE ?= " \
        /usr/local/src/yocto/meta \
        /usr/local/src/yocto/meta-yocto \
        "
                </literallayout>
                Adding the layer to this file enables the build system to
                locate the layer during the build.
                </para>
        </section>
    </section>

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

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

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

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

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

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

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

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

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

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

            <para>
                To understand how these features work, the best reference is
                <filename>meta/classes/core-image.bbclass</filename>.
                In summary, the file looks at the contents of the
                <filename>IMAGE_FEATURES</filename> variable and then maps
                those contents into a set of package groups.
                Based on this information, the build system automatically
                adds the appropriate packages to the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></ulink>
                variable.
                Effectively, you are enabling extra features by extending the
                class or creating a custom class for use with specialized image
                <filename>.bb</filename> files.
            </para>

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

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

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

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

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

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

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

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

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

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

            <para>
                For complex custom images, the best approach for customizing
                an image is to create a custom package group recipe that is
                used to build the image or images.
                A good example of a package group recipe is
                <filename>meta/recipes-core/packagegroups/packagegroup-core-boot.bb</filename>.
                The
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'>PACKAGES</ulink></filename>
                variable lists the package group packages you wish to produce.
                <filename>inherit packagegroup</filename> sets appropriate
                default values and automatically adds <filename>-dev</filename>,
                <filename>-dbg</filename>, and <filename>-ptest</filename>
                complementary packages for every package specified in
                <filename>PACKAGES</filename>.
                Note that the inherit line should be towards
                the top of the recipe, certainly before you set
                <filename>PACKAGES</filename>.
                For each package you specify in <filename>PACKAGES</filename>,
                you can use
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'>RDEPENDS</ulink></filename>
                and
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-RRECOMMENDS'>RRECOMMENDS</ulink></filename>
                entries to provide a list of packages the parent task package
                should contain.
                Following is an example:
                <literallayout class='monospaced'>
     DESCRIPTION = "My Custom Package Groups"

     inherit packagegroup

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

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

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

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

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

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

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

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

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

        <section id='new-recipe-locate-a-base-recipe'>
            <title>Locate a Base Recipe</title>

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

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

     LIC_FILES_CHKSUM = ""

     SRC_URI = ""
     SRC_URI[md5sum] = ""
     SRC_URI[sha256sum] = ""

     S = "${WORKDIR}/${PN}-${PV}"

     inherit &lt;stuff&gt;
                        </literallayout>
                        Modifying this recipe is the recommended method for
                        creating a new recipe.
                        The recipe provides the fundamental areas that you need
                        to include, exclude, or alter to fit your needs.
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

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

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

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

        <section id='understanding-recipe-syntax'>
            <title>Understanding Recipe Syntax</title>

            <para>
                The basic items that make up a BitBake recipe file are
                as follows:
                <itemizedlist>
                    <listitem><para><emphasis>Variable Assignments and Manipulations:</emphasis>
                        Variable assignments allow a value to be assigned to a
                        variable.
                        The assignment can be static text or might include
                        the contents of other variables.
                        In addition to the assignment, appending and prepending
                        operations are also supported.</para>
                        <para>The following example shows some of the ways
                        you can use variables in recipes:
                        <literallayout class='monospaced'>
     S = "${WORKDIR}/postfix-${PV}"
     CFLAGS += "-DNO_ASM"
     SRC_URI_append = " file://fixup.patch"
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Functions:</emphasis>
                        Functions provide a series of actions to be performed.
                        You usually use functions to override the default
                        implementation of a task function or to compliment
                        a default function (i.e. append or prepend to an
                        existing function).
                        Standard functions use <filename>sh</filename> shell
                        syntax, although access to OpenEmbedded variables and
                        internal methods are also available.</para>
                        <para>The following is an example function from the
                        <filename>sed</filename> recipe:
                        <literallayout class='monospaced'>
     do_install () {
         autotools_do_install
         install -d ${D}${base_bindir}
         mv ${D}${bindir}/sed ${D}${base_bindir}/sed.${PN}
     }
                        </literallayout>
                        It is also possible to implement new functions that
                        are called between existing tasks as long as the
                        new functions are not replacing or complimenting the
                        default functions.
                        You can implement functions in Python
                        instead of shell.
                        Both of these options are not seen in the majority of
                        recipes.</para></listitem>
                    <listitem><para><emphasis>Keywords:</emphasis>
                        BitBake recipes use only a few keywords.
                        You use keywords to include common
                        functions (<filename>inherit</filename>), load parts
                        of a recipe from other files
                        (<filename>include</filename> and
                        <filename>require</filename>) and export variables
                        to the environment (<filename>export</filename>).</para>
                        <para>The following example shows the use of some of
                        these keywords:
                        <literallayout class='monospaced'>
     export POSTCONF = "${STAGING_BINDIR}/postconf"
     inherit autoconf
     require otherfile.inc
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Comments:</emphasis>
                        Any lines that begin with the hash character
                        (<filename>#</filename>) are treated as comment lines
                        and are ignored:
                        <literallayout class='monospaced'>
     # This is a comment
                        </literallayout>
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                This next list summarizes the most important and most commonly
                used parts of the recipe syntax.
                For more information on these parts of the syntax, you can
                reference the
                <ulink url='&YOCTO_DOCS_BB_URL;#bitbake-user-manual-metadata'>Syntax and Operators</ulink>
                chapter in the BitBake User Manual.
                <itemizedlist>
                    <listitem><para><emphasis>Line Continuation: <filename>\</filename></emphasis> -
                        Use the backward slash (<filename>\</filename>)
                        character to split a statement over multiple lines.
                        Place the slash character at the end of the line that
                        is to be continued on the next line:
                        <literallayout class='monospaced'>
     VAR = "A really long \
            line"
                        </literallayout>
                        <note>
                            You cannot have any characters including spaces
                            or tabs after the slash character.
                        </note>
                        </para></listitem>
                    <listitem><para><emphasis>Using Variables: <filename>{...}</filename></emphasis> -
                        Use the <filename>${&lt;varname&gt;}</filename> syntax to
                        access the contents of a variable:
                        <literallayout class='monospaced'>
     SRC_URI = "${SOURCEFORGE_MIRROR}/libpng/zlib-${PV}.tar.gz"
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Quote All Assignments: <filename>"&lt;value&gt;"</filename></emphasis> -
                        Use double quotes around the value in all variable
                        assignments.
                        <literallayout class='monospaced'>
     VAR1 = "${OTHERVAR}"
     VAR2 = "The version is ${PV}"
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Conditional Assignment: <filename>?=</filename></emphasis> -
                        Conditional assignment is used to assign a value to
                        a variable, but only when the variable is currently
                        unset.
                        Use the question mark followed by the equal sign
                        (<filename>?=</filename>) to make a "soft" assignment
                        used for conditional assignment.
                        Typically, "soft" assignments are used in the
                        <filename>local.conf</filename> file for variables
                        that are allowed to come through from the external
                        environment.
                        Doing so allows you to actually set variables from
                        the external environment that would otherwise be
                        overwritten.</para>
                        <para>Here is an example:
                        <literallayout class='monospaced'>
     VAR1 ?= "New value"
                        </literallayout>
                        In the previous example, <filename>VAR1</filename> is
                        set to "New value" if it is currently empty.
                        However, if <filename>VAR1</filename> has already been
                        set, it remains unchanged.</para>
                        <para>In this next example, <filename>VAR1</filename>
                        is left with the value "Original value":
                        <literallayout class='monospaced'>
     VAR1 = "Original value"
     VAR1 ?= "New value"
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Appending: <filename>+=</filename></emphasis> -
                        Use the plus character followed by the equals sign
                        (<filename>+=</filename>) to append values to existing
                        variables.
                        <note>
                            This operator adds a space between the existing
                            content of the variable and the new content.
                        </note></para>
                        <para>Here is an example:
                        <literallayout class='monospaced'>
     SRC_URI += "file://fix-makefile.patch"
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Prepending: <filename>=+</filename></emphasis> -
                        Use the equals sign followed by the plus character
                        (<filename>=+</filename>) to prepend values to existing
                        variables.
                        <note>
                            This operator adds a space between the new content
                            and the existing content of the variable.
                        </note></para>
                        <para>Here is an example:
                        <literallayout class='monospaced'>
     VAR =+ "Starts"
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Appending: <filename>_append</filename></emphasis> -
                        Use the <filename>_append</filename> operator to
                        append values to existing variables.
                        This operator does not add any additional space.
                        Also, the operator is applied after all the
                        <filename>+=</filename>, and
                        <filename>=+</filename> operators have been applied and
                        after all <filename>=</filename> assignments have
                        occurred.
                        </para>
                        <para>The following example shows the space being
                        explicitly added to the start to ensure the appended
                        value is not merged with the existing value:
                        <literallayout class='monospaced'>
     SRC_URI_append = " file://fix-makefile.patch"
                        </literallayout>
                        You can also use the <filename>_append</filename>
                        operator with overrides, which results in the actions
                        only being performed for the specified target or
                        machine:
                        <literallayout class='monospaced'>
     SRC_URI_append_sh4 = " file://fix-makefile.patch"
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Prepending: <filename>_prepend</filename></emphasis> -
                        Use the <filename>_prepend</filename> operator to
                        prepend values to existing variables.
                        This operator does not add any additional space.
                        This operator does not add any additional space.
                        Also, the operator is applied after all the
                        <filename>+=</filename>, and
                        <filename>=+</filename> operators have been applied and
                        after all <filename>=</filename> assignments have
                        occurred.
                        </para>
                        <para>The following example shows the space being
                        explicitly added to the end to ensure the prepended
                        value is not merged with the existing value:
                        <literallayout class='monospaced'>
     CFLAGS_prepend = "-I${S}/myincludes "
                        </literallayout>
                        You can also use the <filename>_prepend</filename>
                        operator with overrides, which results in the actions
                        only being performed for the specified target or
                        machine:
                        <literallayout class='monospaced'>
     CFLAGS_prepend_sh4 = " file://fix-makefile.patch"
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Indentation:</emphasis>
                        Use spaces for indentation rather than than tabs.
                        For shell functions, both currently work.
                        However, it is a policy decision of the Yocto Project
                        to use tabs in shell functions.
                        Realize that some layers have a policy to use spaces
                        for all indentation.
                        </para></listitem>
                    <listitem><para><emphasis>Using Python for Complex Operations: <filename>${@&lt;variable&gt;}</filename></emphasis> -
                        For more advanced processing, it is possible to use
                        Python code during variable assignments (e.g.
                        search and replacement on a variable).</para>
                        <para>You indicate Python code using the
                        <filename>${@&lt;variable&gt;}</filename> syntax for the
                        variable assignment:
                        <literallayout class='monospaced'>
     SRC_URI = "ftp://ftp.info-zip.org/pub/infozip/src/zip${@d.getVar('PV',1).replace('.', '')}.tgz
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Shell Function Syntax:</emphasis>
                        Use shell function syntax as if you were writing a shell
                        script when you describe a list of actions to take.
                        You should ensure that your script works with a generic
                        <filename>sh</filename> and that it does not require
                        any <filename>bash</filename> or other shell-specific
                        functionality.
                        The same considerations apply to various system
                        utilities (e.g. <filename>sed</filename>,
                        <filename>grep</filename>, <filename>awk</filename>,
                        and so forth) that you might wish to use.
                        If in doubt, you should check with multiple
                        implementations - including those from BusyBox.
                        </para></listitem>
                </itemizedlist>
            </para>
        </section>

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

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

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

            </para>

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

            <para>
                The temporary work directory is constructed as follows and
                depends on several factors:
                <literallayout class='monospaced'>
     ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
                </literallayout>
                As an example, assume a Source Directory top-level folder named
                <filename>poky</filename>, a default Build Directory at
                <filename>poky/build</filename>, and a
                <filename>qemux86-poky-linux</filename> machine target system.
                Furthermore, suppose your recipe is named
                <filename>foo_1.3.0-r0.bb</filename>.
                In this case, the work directory the build system uses to
                build the package would be as follows:
                <literallayout class='monospaced'>
     poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
                </literallayout>
                Inside this directory you can find sub-directories such as
                <filename>image</filename>, <filename>packages-split</filename>,
                and <filename>temp</filename>.
                After the build, you can examine these to determine how well
                the build went.
                <note>
                    You can find log files for each task in the recipe's
                    <filename>temp</filename> directory (e.g.
                    <filename>poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0/temp</filename>).
                    Log files are named <filename>log.&lt;taskname&gt;</filename>
                    (e.g. <filename>log.do_configure</filename>,
                    <filename>log.do_fetch</filename>, and
                    <filename>log.do_compile</filename>).
                </note>
            </para>

            <para>
                You can find more information about the build process in the
                "<ulink url='&YOCTO_DOCS_REF_URL;#closer-look'>A Closer Look at the Yocto Project Development Environment</ulink>"
                chapter of the Yocto Project Reference Manual.
            </para>

            <para>
                You can also reference the following variables in the
                Yocto Project Reference Manual's glossary for more information:
                <itemizedlist>
                    <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>:
                        The top-level build output directory</listitem>
                    <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-MULTIMACH_TARGET_SYS'><filename>MULTIMACH_TARGET_SYS</filename></ulink>:
                        The target system identifier</listitem>
                    <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink>:
                        The recipe name</listitem>
                    <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-EXTENDPE'><filename>EXTENDPE</filename></ulink>:
                        The epoch - (if
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PE'><filename>PE</filename></ulink>
                        is not specified, which is usually the case for most
                        recipes, then <filename>EXTENDPE</filename> is blank)</listitem>
                    <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>:
                        The recipe version</listitem>
                    <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>:
                        The recipe revision</listitem>
                </itemizedlist>
            </para>
        </section>

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

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

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

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

            <para>
                Here is a simple example from the
                <filename>meta/recipes-devtools/cdrtools/cdrtools-native_3.01a17.bb</filename>
                recipe where the source comes from a single tarball.
                Notice the use of the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>
                variable:
                <literallayout class='monospaced'>
     SRC_URI = "ftp://ftp.berlios.de/pub/cdrecord/alpha/cdrtools-${PV}.tar.bz2"
                </literallayout>
            </para>

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

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

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

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

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

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

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

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

            <para>
                To find these checksums, you can comment the statements out
                and then attempt to build the software.
                The build will produce an error for each missing checksum
                and as part of the error message provide the correct checksum
                string.
                Once you have the correct checksums, simply copy them into your
                recipe for a subsequent build.
            </para>

            <para>
                This final example is a bit more complicated and is from the
                <filename>meta/recipes-sato/rxvt-unicode/rxvt-unicode_9.19.bb</filename>
                recipe.
                The example's <filename>SRC_URI</filename> statement identifies
                multiple files as the source files for the recipe: a tarball, a
                patch file, a desktop file, and an icon.
                <literallayout class='monospaced'>
     SRC_URI = "http://dist.schmorp.de/rxvt-unicode/Attic/rxvt-unicode-${PV}.tar.bz2 \
                file://xwc.patch \
                file://rxvt.desktop \
                file://rxvt.png"
                </literallayout>
            </para>

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

            <para>
                The previous example also specifies a patch file.
                Patch files are files whose names end in
                <filename>.patch</filename> or <filename>.diff</filename>.
                The build system automatically applies patches as described
                in the
                "<link linkend='new-recipe-patching-code'>Patching Code</link>" section.
            </para>
        </section>

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

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

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

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

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

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

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

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

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

<!--

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

     LIC_FILES_CHKSUM = ""

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

     LIC_FILES_CHKSUM = ""

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

        </section>

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

            <para>
                Most software provides some means of setting build-time
                configuration options before compilation.
                Typically, setting these options is accomplished by running a
                configure script with some options, or by modifying a build
                configuration file.
            </para>

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

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

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

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

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

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

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

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

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

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

            <note>
                During the installation process, you might need to modify
                some of the installed files to suit the target layout.
                For example, you might need to replace hard-coded paths in an
                initscript with values of variables provided by the build
                system, such as replacing <filename>/usr/bin/</filename> with
                <filename>${bindir}</filename>.
                If you do perform such modifications during
                <filename>do_install</filename>, be sure to modify the
                destination file after copying rather than before copying.
                Modifying after copying ensures that the build system can
                re-execute <filename>do_install</filename> if needed.
            </note>

            <note>
                <filename>oe_runmake install</filename>, which can be run
                directly or can be run indirectly by the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-autotools'><filename>autotools</filename></ulink>
                and
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-cmake'><filename>cmake</filename></ulink>
                classes, runs <filename>make install</filename> in parallel.
                Sometimes, a Makefile can have missing dependencies between
                targets that can result in race conditions.
                If you experience intermittent failures during
                <filename>do_install</filename>, you might be able to work
                around them by disabling parallel Makefile installs
                by adding the following to the recipe:
                <literallayout class='monospaced'>
     PARALLEL_MAKEINST = ""
                </literallayout>
                See
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKEINST'><filename>PARALLEL_MAKEINST</filename></ulink>
                for additional information.
            </note>
        </section>

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

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

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

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

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

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

            <para>
                The <filename>do_package</filename> task splits the files
                produced by the recipe into logical components.
                Even software that produces a single binary might still have
                debug symbols, documentation, and other logical components
                that should be split out.
                The <filename>do_package</filename> task ensures that files
                are split up and packaged correctly.
            </para>

            <para>
                After you build your software, you need to be sure your packages
                are correct.
                Examine the
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}/packages-split</filename>
                directory and make sure files are where you expect them to be.
            </para>

            <para>
                If you discover problems, you can set
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'><filename>PACKAGES</filename></ulink>,
                <ulink url='&YOCTO_DOCS_REF_URL;#var-FILES'><filename>FILES</filename></ulink>,
                <filename>do_install(_append)</filename>, and so forth as
                needed.
            </para>

            <para>
                See the
                "<link linkend='splitting-an-application-into-multiple-packages'>Splitting an Application into Multiple Packages</link>"
                section for an example that shows how you might split
                your software into more than one package.
            </para>

            <para>
                For an example showing how to install a post-installation
                script, see the
                "<link linkend='new-recipe-post-installation-scripts'>Post-Installation Scripts</link>"
                section.
            </para>
        </section>

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

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

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

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

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

            <para>
                A post-installation function has the following structure:
                <literallayout class='monospaced'>
     pkg_postinst_PACKAGENAME () {
     #!/bin/sh -e
     # Commands to carry out
     }
                </literallayout>
            </para>

            <para>
                The script defined in the post-installation function is
                called when the root filesystem is created.
                If the script succeeds, the package is marked as installed.
                If the script fails, the package is marked as unpacked and
                the script is executed when the image boots again.
            </para>

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

            <para>
                The previous example delays execution until the image boots
                again because the
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-D'>D</ulink></filename>
                variable points to the directory containing the image when
                the root filesystem is created at build time but is unset
                when executed on the first boot.
            </para>

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

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

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

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

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

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

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

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

     SRC_URI = "file://helloworld.c"

     S = "${WORKDIR}"

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

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

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

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

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

     inherit autotools gettext
                     </literallayout>
                </para>

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

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

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

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

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

     SRC_URI = "git://git.infradead.org/mtd-utils.git;protocol=git;tag=995cfe51b0a3cf32f381c140bf72b21bf91cef1b \
	     	file://add-exclusion-to-mkfs-jffs2-git-2.patch"

     S = "${WORKDIR}/git/"

     PR = "r1"

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

     do_install () {
	     oe_runmake install DESTDIR=${D} SBINDIR=${sbindir} MANDIR=${mandir} \
            INCLUDEDIR=${includedir}
	     install -d ${D}${includedir}/mtd/
	     for f in ${S}/include/mtd/*.h; do
	     	install -m 0644 $f ${D}${includedir}/mtd/
	     done
     }

     PARALLEL_MAKE = ""

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

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

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

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

     SUMMARY = "X11 Pixmap library"
     LICENSE = "X-BSD"
     LIC_FILES_CHKSUM = "file://COPYING;md5=3e07763d16963c3af12db271a31abaa5"
     DEPENDS += "libxext libsm libxt"
     PR = "r3"
     PE = "1"

     XORG_PN = "libXpm"

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

            <para>
                This section overviews the Multilib process only.
                For more details on how to implement Multilib, see the
                <ulink url='&YOCTO_WIKI_URL;/wiki/Multilib'>Multilib</ulink> wiki
                page.
            </para>

            <para>
                Aside from this wiki page, several examples exist in the
                <filename>meta-skeleton</filename> layer found in the
               <link linkend='source-directory'>Source Directory</link>:
                <itemizedlist>
                    <listitem><para><filename>conf/multilib-example.conf</filename>
                        configuration file</para></listitem>
                    <listitem><para><filename>conf/multilib-example2.conf</filename>
                        configuration file</para></listitem>
                    <listitem><para><filename>recipes-multilib/images/core-image-multilib-example.bb</filename>
                        recipe</para></listitem>
                </itemizedlist>
            </para>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        <para>
            Configuring the Yocto Project kernel consists of making sure the <filename>.config</filename>
            file has all the right information in it for the image you are building.
            You can use the <filename>menuconfig</filename> tool and configuration fragments to
            make sure your <filename>.config</filename> file is just how you need it.
            This section describes how to use <filename>menuconfig</filename>, create and use
            configuration fragments, and how to interactively tweak your <filename>.config</filename>
            file to create the leanest kernel configuration file possible.
        </para>

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

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

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

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

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

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

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

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

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

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

            <para>
                Configuration fragments are simply kernel options that appear in a file
                placed where the OpenEmbedded build system can find and apply them.
                Syntactically, the configuration statement is identical to what would appear
                in the <filename>.config</filename> file, which is in the
                <link linkend='build-directory'>Build Directory</link> in
                <filename>tmp/work/&lt;arch&gt;-poky-linux/linux-yocto-&lt;release-specific-string&gt;/linux-&lt;arch&gt;-&lt;build-type&gt;</filename>.
            </para>

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

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

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

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

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

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

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

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

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

    <section id="patching-the-kernel">
        <title>Patching the Kernel</title>

        <para>
            Patching the kernel involves changing or adding configurations to an existing kernel,
            changing or adding recipes to the kernel that are needed to support specific hardware features,
            or even altering the source code itself.
            <note>
                You can use the <filename>yocto-kernel</filename> script
                found in the <link linkend='source-directory'>Source Directory</link>
                under <filename>scripts</filename> to manage kernel patches and configuration.
                See the "<ulink url='&YOCTO_DOCS_BSP_URL;#managing-kernel-patches-and-config-items-with-yocto-kernel'>Managing kernel Patches and Config Items with yocto-kernel</ulink>"
                section in the Yocto Project Board Support Packages (BSP) Developer's Guide for
                more information.</note>
        </para>

        <para>
            This example creates a simple patch by adding some QEMU emulator console
            output at boot time through <filename>printk</filename> statements in the kernel's
            <filename>calibrate.c</filename> source code file.
            Applying the patch and booting the modified image causes the added
            messages to appear on the emulator's console.
        </para>

        <para>
            The example assumes a clean build exists for the <filename>qemux86</filename>
            machine in a
            <link linkend='source-directory'>Source Directory</link>
            named <filename>poky</filename>.
            Furthermore, the <link linkend='build-directory'>Build Directory</link> is
            <filename>build</filename> and is located in <filename>poky</filename> and
            the kernel is based on the Linux 3.4 kernel.
            For general information on how to configure the most efficient build, see the
            "<ulink url='&YOCTO_DOCS_QS_URL;#building-image'>Building an Image</ulink>" section
            in the Yocto Project Quick Start.
        </para>

        <para>
            Also, for more information on patching the kernel, see the
            "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#applying-patches'>Applying Patches</ulink>"
            section in the Yocto Project Linux Kernel Development Manual.
        </para>

        <section id='create-a-layer-for-your-changes'>
            <title>Create a Layer for your Changes</title>

            <para>
                The first step is to create a layer so you can isolate your
                changes.
                Rather than use the <filename>yocto-layer</filename> script
                to create the layer, this example steps through the process
                by hand.
                If you want information on the script that creates a general
                layer, see the
                "<link linkend='creating-a-general-layer-using-the-yocto-layer-script'>Creating a General Layer Using the yocto-layer Script</link>"
                section.
            </para>

            <para>
                These two commands create a directory you can use for your
                layer:
                <literallayout class='monospaced'>
     $ cd ~/poky
     $ mkdir meta-mylayer
                </literallayout>
                Creating a directory that follows the Yocto Project layer naming
                conventions sets up the layer for your changes.
                The layer is where you place your configuration files, append
                files, and patch files.
                To learn more about creating a layer and filling it with the
                files you need, see the "<link linkend='understanding-and-creating-layers'>Understanding
                and Creating Layers</link>" section.
            </para>
        </section>

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

            <para>
                Each time you build a kernel image, the kernel source code is fetched
                and unpacked into the following directory:
                <literallayout class='monospaced'>
     ${S}/linux
                </literallayout>
                See the "<link linkend='finding-the-temporary-source-code'>Finding the Temporary Source Code</link>"
                section and the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink> variable
                for more information about where source is kept during a build.
            </para>

            <para>
                For this example, we are going to patch the
                <filename>init/calibrate.c</filename> file
                by adding some simple console <filename>printk</filename> statements that we can
                see when we boot the image using QEMU.
            </para>
        </section>

        <section id='creating-the-patch'>
            <title>Creating the Patch</title>

            <para>
                Two methods exist by which you can create the patch:
                <link linkend='using-a-git-workflow'>Git workflow</link> and
                <link linkend='using-a-quilt-workflow'>Quilt workflow</link>.
                For kernel patches, the Git workflow is more appropriate.
                This section assumes the Git workflow and shows the steps specific to
                this example.
                <orderedlist>
                    <listitem><para><emphasis>Change the working directory</emphasis>:
                        Change to where the kernel source code is before making
                        your edits to the <filename>calibrate.c</filename> file:
                        <literallayout class='monospaced'>
     $ cd ~/poky/build/tmp/work/qemux86-poky-linux/linux-yocto-${PV}-${PR}/linux
                        </literallayout>
                        Because you are working in an established Git repository,
                        you must be in this directory in order to commit your changes
                        and create the patch file.
                        <note>The <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink> and
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink> variables
                            represent the version and revision for the
                            <filename>linux-yocto</filename> recipe.
                            The <filename>PV</filename> variable includes the Git meta and machine
                            hashes, which make the directory name longer than you might
                            expect.
                        </note></para></listitem>
                    <listitem><para><emphasis>Edit the source file</emphasis>:
                        Edit the <filename>init/calibrate.c</filename> file to have the
                        following changes:
                        <literallayout class='monospaced'>
     void calibrate_delay(void)
     {
         unsigned long lpj;
         static bool printed;
         int this_cpu = smp_processor_id();

         printk("*************************************\n");
         printk("*                                   *\n");
         printk("*        HELLO YOCTO KERNEL         *\n");
         printk("*                                   *\n");
         printk("*************************************\n");

     	if (per_cpu(cpu_loops_per_jiffy, this_cpu)) {
               .
               .
               .
                        </literallayout></para></listitem>
                    <listitem><para><emphasis>Stage and commit your changes</emphasis>:
                        These Git commands display the modified file, stage it, and then
                        commit the file:
                        <literallayout class='monospaced'>
     $ git status
     $ git add init/calibrate.c
     $ git commit -m "calibrate: Add printk example"
                        </literallayout></para></listitem>
                    <listitem><para><emphasis>Generate the patch file</emphasis>:
                        This Git command creates the a patch file named
                        <filename>0001-calibrate-Add-printk-example.patch</filename>
                        in the current directory.
                        <literallayout class='monospaced'>
     $ git format-patch -1
                        </literallayout>
                        </para></listitem>
                </orderedlist>
            </para>
        </section>

        <section id='set-up-your-layer-for-the-build'>
            <title>Set Up Your Layer for the Build</title>

            <para>These steps get your layer set up for the build:
                <orderedlist>
                    <listitem><para><emphasis>Create additional structure</emphasis>:
                        Create the additional layer structure:
                        <literallayout class='monospaced'>
     $ cd ~/poky/meta-mylayer
     $ mkdir conf
     $ mkdir recipes-kernel
     $ mkdir recipes-kernel/linux
     $ mkdir recipes-kernel/linux/linux-yocto
                         </literallayout>
                         The <filename>conf</filename> directory holds your configuration files, while the
                         <filename>recipes-kernel</filename> directory holds your append file and
                         your patch file.</para></listitem>
                    <listitem><para><emphasis>Create the layer configuration file</emphasis>:
                        Move to the <filename>meta-mylayer/conf</filename> directory and create
                        the <filename>layer.conf</filename> file as follows:
                        <literallayout class='monospaced'>
     # We have a conf and classes directory, add to BBPATH
     BBPATH .= ":${LAYERDIR}"

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

     BBFILE_COLLECTIONS += "mylayer"
     BBFILE_PATTERN_mylayer = "^${LAYERDIR}/"
     BBFILE_PRIORITY_mylayer = "5"
                         </literallayout>
                         Notice <filename>mylayer</filename> as part of the last three
                         statements.</para></listitem>
                    <listitem><para><emphasis>Create the kernel recipe append file</emphasis>:
                        Move to the <filename>meta-mylayer/recipes-kernel/linux</filename> directory and create
                        the <filename>linux-yocto_3.4.bbappend</filename> file as follows:
                        <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"

     SRC_URI += "file://0001-calibrate-Add-printk-example.patch"
                        </literallayout>
                        The <ulink url='&YOCTO_DOCS_REF_URL;#var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></ulink>
                        and <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                        statements enable the OpenEmbedded build system to find the patch file.
                        For more information on using append files, see the
                        "<link linkend='using-bbappend-files'>Using .bbappend Files</link>"
                        section.
                        </para></listitem>
                    <listitem><para><emphasis>Put the patch file in your layer</emphasis>:
                        Move the <filename>0001-calibrate-Add-printk-example.patch</filename> file to
                        the <filename>meta-mylayer/recipes-kernel/linux/linux-yocto</filename>
                        directory.</para></listitem>
                </orderedlist>
            </para>
        </section>

        <section id='set-up-for-the-build'>
            <title>Set Up for the Build</title>

            <para>
                Do the following to make sure the build parameters are set up for the example.
                Once you set up these build parameters, they do not have to change unless you
                change the target architecture of the machine you are building:
                <itemizedlist>
                    <listitem><para><emphasis>Build for the correct target architecture:</emphasis> Your
                        selected <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
                        definition within the <filename>local.conf</filename> file in the
                        <link linkend='build-directory'>Build Directory</link>
                        specifies the target architecture used when building the Linux kernel.
                        By default, <filename>MACHINE</filename> is set to
                        <filename>qemux86</filename>, which specifies a 32-bit
                        <trademark class='registered'>Intel</trademark> Architecture
                        target machine suitable for the QEMU emulator.</para></listitem>
                    <listitem><para><emphasis>Identify your <filename>meta-mylayer</filename>
                        layer:</emphasis> The
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-BBLAYERS'><filename>BBLAYERS</filename></ulink>
                        variable in the
                        <filename>bblayers.conf</filename> file found in the
                        <filename>poky/build/conf</filename> directory needs to have the path to your local
                        <filename>meta-mylayer</filename> layer.
                        By default, the <filename>BBLAYERS</filename> variable contains paths to
                        <filename>meta</filename>, <filename>meta-yocto</filename>, and
                        <filename>meta-yocto-bsp</filename> in the
                        <filename>poky</filename> Git repository.
                        Add the path to your <filename>meta-mylayer</filename> location:
                        <literallayout class='monospaced'>
     BBLAYERS ?= " \
       $HOME/poky/meta \
       $HOME/poky/meta-yocto \
       $HOME/poky/meta-yocto-bsp \
       $HOME/poky/meta-mylayer \
       "

     BBLAYERS_NON_REMOVABLE ?= " \
       $HOME/poky/meta \
       $HOME/poky/meta-yocto \
       "
                        </literallayout></para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='build-the-modified-qemu-kernel-image'>
            <title>Build the Modified QEMU Kernel Image</title>

            <para>
                The following steps build your modified kernel image:
                <orderedlist>
                    <listitem><para><emphasis>Be sure your build environment is initialized</emphasis>:
                        Your environment should be set up since you previously sourced
                        the
                        <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink>
                        script.
                        If it is not, source the script again from <filename>poky</filename>.
                        <literallayout class='monospaced'>
     $ cd ~/poky
     $ source &OE_INIT_FILE;
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Clean up</emphasis>:
                        Be sure to clean the shared state out by running the
                        <filename>cleansstate</filename> BitBake task as follows from your Build Directory:
                        <literallayout class='monospaced'>
     $ bitbake -c cleansstate linux-yocto
                        </literallayout></para>
                        <para><note>Never remove any files by hand from the <filename>tmp/deploy</filename>
                        directory inside the
                        <link linkend='build-directory'>Build Directory</link>.
                        Always use the various BitBake clean tasks to clear out previous
                        build artifacts.
                        </note></para></listitem>
                    <listitem><para><emphasis>Build the image</emphasis>:
                        Next, build the kernel image using this command:
                        <literallayout class='monospaced'>
     $ bitbake -k linux-yocto
                        </literallayout></para></listitem>
                </orderedlist>
            </para>
        </section>

        <section id='boot-the-image-and-verify-your-changes'>
            <title>Boot the Image and Verify Your Changes</title>

            <para>
                These steps boot the image and allow you to see the changes
                <orderedlist>
                    <listitem><para><emphasis>Boot the image</emphasis>:
                        Boot the modified image in the QEMU emulator
                        using this command:
                        <literallayout class='monospaced'>
     $ runqemu qemux86
                        </literallayout></para></listitem>
                    <listitem><para><emphasis>Verify the changes</emphasis>:
                        Log into the machine using <filename>root</filename> with no password and then
                        use the following shell command to scroll through the console's boot output.
                        <literallayout class='monospaced'>
     # dmesg | less
                        </literallayout>
                        You should see the results of your <filename>printk</filename> statements
                        as part of the output.</para></listitem>
                </orderedlist>
            </para>
        </section>
    </section>

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

        <para>
            The Yocto Project has security flags that you can enable that
            help make your build output more secure.
            The security flags are in the
            <filename>meta/conf/distro/include/security_flags.inc</filename>
            file in your
            <link linkend='source-directory'>Source Directory</link>
            (e.g. <filename>poky</filename>).
        </para>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


        </section>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        <section id='incrementing-a-package-revision-number'>
            <title>Incrementing a Package Revision Number</title>

            <para>
                If a committed change results in changing the package output,
                then the value of the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>
                variable needs to be increased (or "bumped").
                Increasing <filename>PR</filename> occurs one of two ways:
                <itemizedlist>
                    <listitem><para>Automatically using a Package Revision
                        Service (PR Service).</para></listitem>
                    <listitem><para>Manually incrementing the
                        <filename>PR</filename> variable.</para></listitem>
                </itemizedlist>
            </para>

            <para>
                Given that one of the challenges any build system and its
                users face is how to maintain a package feed that is compatible
                with existing package manager applications such as
                RPM, APT, and OPKG, using an automated system is much
                preferred over a manual system.
                In either system, the main requirement is that version
                numbering increases in a linear fashion and that a number of
                version components exist that support that linear progression.
            </para>

            <para>
                The following two sections provide information on the PR Service
                and on manual <filename>PR</filename> bumping.
            </para>

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

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

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

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

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

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

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

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

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

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

                <note>
                    <para>The OpenEmbedded build system does not maintain
                    <filename>PR</filename> information as part of the
                    shared state (sstate) packages.
                    If you maintain an sstate feed, its expected that either
                    all your building systems that contribute to the sstate
                    feed use a shared PR Service, or you do not run a PR
                    Service on any of your building systems.
                    Having some systems use a PR Service while others do
                    not leads to obvious problems.</para>
                    <para>For more information on shared state, see the
                    "<ulink url='&YOCTO_DOCS_REF_URL;#shared-state-cache'>Shared State Cache</ulink>"
                    section in the Yocto Project Reference Manual.</para>
                </note>
            </section>

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

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

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

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

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

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

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

        <section id="usingpoky-configuring-DISTRO_PN_ALIAS">
            <title>Handling a Package Name Alias</title>
            <para>
                Sometimes a package name you are using might exist under an alias or as a similarly named
                package in a different distribution.
                The OpenEmbedded build system implements a <filename>distro_check</filename>
                task that automatically connects to major distributions
                and checks for these situations.
                If the package exists under a different name in a different distribution, you get a
                <filename>distro_check</filename> mismatch.
                You can resolve this problem by defining a per-distro recipe name alias using the
                <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_PN_ALIAS'>DISTRO_PN_ALIAS</ulink></filename>
                variable.
            </para>

            <para>
                Following is an example that shows how you specify the <filename>DISTRO_PN_ALIAS</filename>
                variable:
                <literallayout class='monospaced'>
     DISTRO_PN_ALIAS_pn-PACKAGENAME = "distro1=package_name_alias1 \
                                       distro2=package_name_alias2 \
                                       distro3=package_name_alias3 \
                                       ..."
                </literallayout>
            </para>

            <para>
                If you have more than one distribution alias, separate them with a space.
                Note that the build system currently automatically checks the
                Fedora, OpenSUSE, Debian, Ubuntu,
                and Mandriva distributions for source package recipes without having to specify them
                using the <filename>DISTRO_PN_ALIAS</filename> variable.
                For example, the following command generates a report that lists the Linux distributions
                that include the sources for each of the recipes.
                <literallayout class='monospaced'>
     $ bitbake world -f -c distro_check
                </literallayout>
                The results are stored in the <filename>build/tmp/log/distro_check-${DATETIME}.results</filename>
                file found in the
                <link linkend='source-directory'>Source Directory</link>.
            </para>
        </section>

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

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

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

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

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

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

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

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

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

     Optional arguments

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

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

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

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

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

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

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

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

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

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

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

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

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

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

                <para>
                    When BitBake generates packages it needs to know
                    what format or formats to use.
                    In your configuration, you use the
                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></ulink>
                    variable to specify the format.
                    <note>
                        You can choose to have more than one format but you must
                        provide at least one.
                    </note>
                </para>

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

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

                <para>
                    As described below in the
                    "<link linkend='runtime-package-management-target-ipk'>Using IPK</link>"
                    section, if you are using IPK as your package format, you
                    can make use of the
                    <filename>distro-feed-configs</filename> recipe provided
                    by <filename>meta-oe</filename> in order to configure your
                    target to use your IPK databases.
                </para>

                <para>
                    When your build is complete, your packages reside in the
                    <filename>${TMPDIR}/deploy/&lt;package-format&gt;</filename>
                    directory.
                    For example, if <filename>${TMPDIR}</filename>
                    is <filename>tmp</filename> and your selected package type
                    is IPK, then your IPK packages are available in
                    <filename>tmp/deploy/ipk</filename>.
                </para>
            </section>

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

                <para>
                    Typically, packages are served from a server using
                    HTTP.
                    However, other protocols are possible.
                    If you want to use HTTP, then setup and configure a
                    web server, such as Apache 2 or lighttpd, on the machine
                    serving the packages.
                </para>

                <para>
                    As previously mentioned, the build machine can act as the
                    package server.
                    In the following sections that describe server machine
                    setups, the build machine is assumed to also be the server.
                </para>

                <section id='package-server-apache'>
                    <title>Serving Packages via Apache 2</title>

                    <para>
                        This example assumes you are using the Apache 2
                        server:
                        <orderedlist>
                            <listitem><para>
                                Add the directory to your Apache
                                configuration, which you can find at
                                <filename>/etc/httpd/conf/httpd.conf</filename>.
                                Use commands similar to these on the
                                development system.
                                These example commands assume a top-level
                                <link linkend='source-directory'>Source Directory</link>
                                named <filename>poky</filename> in your home
                                directory.
                                The example also assumes an RPM package type.
                                If you are using a different package type, such
                                as IPK, use "ipk" in the pathnames:
                                <literallayout class='monospaced'>
     &lt;VirtualHost *:80&gt;
       ....
         Alias /rpm ~/poky/build/tmp/deploy/rpm
         &lt;Directory "~/poky/build/tmp/deploy/rpm"&gt;
           Options +Indexes
         &lt;/Directory&gt;
     &lt;/VirtualHost&gt;
                                </literallayout></para></listitem>
                            <listitem><para>
                                Reload the Apache configuration as described
                                in this step.
                                For all commands, be sure you have root
                                privileges.
                                </para>

                                <para>
                                If your development system is using Fedora or
                                CentOS, use the following:
                                <literallayout class='monospaced'>
     # service httpd reload
                                </literallayout>
                                For Ubuntu and Debian, use the following:
                                <literallayout class='monospaced'>
     # /etc/init.d/apache2 reload
                                </literallayout>
                                For OpenSUSE, use the following:
                                <literallayout class='monospaced'>
     # /etc/init.d/apache2 reload
                                </literallayout></para></listitem>
                            <listitem><para>
                                If you are using Security-Enhanced Linux
                                (SELinux), you need to label the files as
                                being accessible through Apache.
                                Use the following command from the development
                                host.
                                This example assumes RPM package types:
                                <literallayout class='monospaced'>
     # chcon -R -h -t httpd_sys_content_t tmp/deploy/rpm
                                </literallayout></para></listitem>
                        </orderedlist>
                    </para>
                </section>

                <section id='package-server-lighttpd'>
                    <title>Serving Packages via lighttpd</title>

                    <para>
                        If you are using lighttpd, all you need
                        to do is to provide a link from your
                        <filename>${TMPDIR}/deploy/&lt;package-format&gt;</filename>
                        directory to lighttpd's document-root.
                        You can determine the specifics of your lighttpd
                        installation by looking through its configuration file,
                        which is usually found at:
                        <filename>/etc/lighttpd/lighttpd.conf</filename>.
                    </para>

                    <para>
                        For example, if you are using IPK, lighttpd's
                        document-root is set to
                        <filename>/var/www/lighttpd</filename>, and you had
                        packages for a target named "BOARD",
                        then you might create a link from your build location
                        to lighttpd's document-root as follows:
                        <literallayout class='monospaced'>
    # ln -s $(PWD)/tmp/deploy/ipk /var/www/lighttpd/BOARD-dir
                        </literallayout>
                    </para>

                    <para>
                        At this point, you need to start the lighttpd server.
                        The method used to start the server varies by
                        distribution.
                        However, one basic method that starts it by hand is:
                        <literallayout class='monospaced'>
    # lighttpd -f /etc/lighttpd/lighttpd.conf
                        </literallayout>
                    </para>
                </section>
            </section>

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

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

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

                    <para>
                        The application for performing runtime package
                        management of RPM packages on the target is called
                        <filename>smart</filename>.
                    </para>

                    <para>
                        On the target machine, you need to inform
                        <filename>smart</filename> of every package database
                        you want to use.
                        As an example, suppose your target device can use the
                        following three package databases from a server named
                        <filename>server.name</filename>:
                        <filename>all</filename>, <filename>i586</filename>,
                        and <filename>qemux86</filename>.
                        Given this example, issue the following commands on the
                        target:
                        <literallayout class='monospaced'>
     # smart channel --add all type=rpm-md baseurl=http://server.name/rpm/all
     # smart channel --add i585 type=rpm-md baseurl=http://server.name/rpm/i586
     # smart channel --add qemux86 type=rpm-md baseurl=http://server.name/rpm/qemux86
                        </literallayout>
                        Also from the target machine, fetch the repository
                        information using this command:
                        <literallayout class='monospaced'>
     # smart update
                        </literallayout>
                        You can now use the <filename>smart query</filename>
                        and <filename>smart install</filename> commands to
                        find and install packages from the repositories.
                    </para>
                </section>

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

                    <para>
                        The application for performing runtime package
                        management of IPK packages on the target is called
                        <filename>opkg</filename>.
                    </para>

                    <para>
                        In order to inform <filename>opkg</filename> of the
                        package databases you want to use, simply create one
                        or more <filename>*.conf</filename> files in the
                        <filename>/etc/opkg</filename> directory on the target.
                        The <filename>opkg</filename> application uses them
                        to find its available package databases.
                        As an example, suppose you configured your HTTP server
                        on your machine named
                        <filename>www.mysite.com</filename> to serve files
                        from a <filename>BOARD-dir</filename> directory under
                        its document-root.
                        In this case, you might create a configuration
                        file on the target called
                        <filename>/etc/opkg/base-feeds.conf</filename> that
                        contains:
                        <literallayout class='monospaced'>
     src/gz all http://www.mysite.com/BOARD-dir/all
     src/gz armv7a http://www.mysite.com/BOARD-dir/armv7a
     src/gz beaglebone http://www.mysite.com/BOARD-dir/beaglebone
                        </literallayout>
                    </para>

                    <para>
                        As a way of making it easier to generate and make
                        these IPK configuration files available on your
                        target, simply define
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-FEED_DEPLOYDIR_BASE_URI'><filename>FEED_DEPLOYDIR_BASE_URI</filename></ulink>
                        to point to your server and the location within the
                        document-root which contains the databases.
                        For example: if you are serving your packages over
                        HTTP, your server's IP address is 192.168.7.1, and
                        your databases are located in a directory called
                        <filename>BOARD-dir</filename> underneath your HTTP
                        server's document-root, you need to set
                        <filename>FEED_DEPLOYDIR_BASE_URI</filename> to
                        <filename>http://192.168.7.1/BOARD-dir</filename> and
                        a set of configuration files will be generated for you
                        in your target to work with this feed.
                    </para>

                    <para>
                        On the target machine, fetch (or refresh) the
                        repository information using this command:
                        <literallayout class='monospaced'>
     # opkg update
                        </literallayout>
                        You can now use the <filename>opkg list</filename> and
                        <filename>opkg install</filename> commands to find and
                        install packages from the repositories.
                    </para>
                </section>
            </section>
        </section>

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

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

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

            <note>
                A recipe is "ptest-enabled" if it inherits the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-ptest'><filename>ptest</filename></ulink>
                class.
            </note>

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

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

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

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

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

                <para>
                    In order to enable a recipe to run installed ptests
                    on target hardware,
                    you need to prepare the recipes that build the packages
                    you want to test.
                    Here is what you have to do for each recipe:
                    <itemizedlist>
                        <listitem><para><emphasis>Be sure the recipe
                            inherits the
                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-ptest'><filename>ptest</filename></ulink>
                            class:</emphasis>
                            Include the following line in each recipe:
                            <literallayout class='monospaced'>
     inherit ptest
                            </literallayout>
                            </para></listitem>
                        <listitem><para><emphasis>Create <filename>run-ptest</filename>:</emphasis>
                            This script starts your test.
                            Locate the script where you will refer to it
                            using
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>.
                            Here is an example that starts a test for
                            <filename>dbus</filename>:
                            <literallayout class='monospaced'>
     #!/bin/sh
     cd test
     make -k runtest-TESTS
                            </literallayout>
                            </para></listitem>
                        <listitem><para><emphasis>Ensure dependencies are
                            met:</emphasis>
                            If the test adds build or runtime dependencies
                            that normally do not exist for the package
                            (such as requiring "make" to run the test suite),
                            use the
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
                            and
                            <ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'><filename>RDEPENDS</filename></ulink>
                            variables in your recipe in order for the package
                            to meet the dependencies.
                            Here is an example where the package has a runtime
                            dependency on "make":
                            <literallayout class='monospaced'>
     RDEPENDS_${PN}-ptest += "make"
                            </literallayout>
                            </para></listitem>
                        <listitem><para><emphasis>Add a function to build the
                            test suite:</emphasis>
                            Not many packages support cross-compilation of
                            their test suites.
                            Consequently, you usually need to add a
                            cross-compilation function to the package.
                            </para>
                            <para>Many packages based on Automake compile and
                            run the test suite by using a single command
                            such as <filename>make check</filename>.
                            However, the native <filename>make check</filename>
                            builds and runs on the same computer, while
                            cross-compiling requires that the package is built
                            on the host but executed on the target.
                            The built version of Automake that ships with the
                            Yocto Project includes a patch that separates
                            building and execution.
                            Consequently, packages that use the unaltered,
                            patched version of <filename>make check</filename>
                            automatically cross-compiles.</para>
                            <para>However, you still must add a
                            <filename>do_compile_ptest</filename> function to
                            build the test suite.
                            Add a function similar to the following to your
                            recipe:
                            <literallayout class='monospaced'>
     do_compile_ptest() {
        oe_runmake buildtest-TESTS
     }
                            </literallayout>
                            </para></listitem>
                       <listitem><para><emphasis>Ensure special configurations
                            are set:</emphasis>
                            If the package requires special configurations
                            prior to compiling the test code, you must
                            insert a <filename>do_configure_ptest</filename>
                            function into the recipe.
                            </para></listitem>
                       <listitem><para><emphasis>Install the test
                            suite:</emphasis>
                            The <filename>ptest</filename> class
                            automatically copies the file
                            <filename>run-ptest</filename> to the target and
                            then runs make <filename>install-ptest</filename>
                            to run the tests.
                            If this is not enough, you need to create a
                            <filename>do_install_ptest</filename> function and
                            make sure it gets called after the
                            "make install-ptest" completes.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>
        </section>
    </section>

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

        <para>
            By default, the OpenEmbedded build system uses the
            <link linkend='build-directory'>Build Directory</link> to
            build source code.
            The build process involves fetching the source files, unpacking
            them, and then patching them if necessary before the build takes
            place.
        </para>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

                <para>
                    In order to run tests on hardware, you need to set
                    <filename>TEST_TARGET</filename> to an appropriate value.
                    For QEMU, you do not have to change anything, the default
                    value is "QemuTarget".
                    For running tests on hardware, two options exist:
                    "SimpleRemoteTarget" and "GummibootTarget".
                    <itemizedlist>
                        <listitem><para><emphasis>"SimpleRemoteTarget":</emphasis>
                            Choose "SimpleRemoteTarget" if you are going to
                            run tests on a target system that is already
                            running the image to be tested and is available
                            on the network.
                            You can use "SimpleRemoteTarget" in conjunction
                            with either real hardware or an image running
                            within a separately started QEMU or any
                            other virtual machine manager.
                            </para></listitem>
                        <listitem><para><emphasis>"GummibootTarget":</emphasis>
                            Choose "GummibootTarget" if your hardware is
                            an EFI-based machine with
                            <filename>gummiboot</filename> as bootloader and
                            <filename>core-image-testmaster</filename>
                            (or something similar) is installed.
                            Also, your hardware under test must be in a
                            DHCP-enabled network that gives it the same IP
                            address for each reboot.</para>
                            <para>If you choose "GummibootTarget", there are
                            additional requirements and considerations.
                            See the
                            "<link linkend='selecting-gummiboottarget'>Selecting GummibootTarget</link>"
                            section, which follows, for more information.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>

            <section id='selecting-gummiboottarget'>
                <title>Selecting GummibootTarget</title>

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

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

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

                <para>
                    Here is some additional information regarding running
                    "GummibootTarget" as your test target:
                    <itemizedlist>
                        <listitem><para>
                            You can use
                            <filename>TEST_POWERCONTROL_CMD</filename>
                            together with
                            <filename>TEST_POWERCONTROL_EXTRA_ARGS</filename>
                            as a command that runs on the host and does power
                            cycling.
                            The test code passes one argument to that command:
                            off, on or cycle (off then on).
                            Here is an example that could appear in your
                            <filename>local.conf</filename> file:
                            <literallayout class='monospaced'>
     TEST_POWERCONTROL_CMD = "powercontrol.exp test 10.11.12.1 nuc1"
                            </literallayout>
                            In this example, the expect script does the
                            following:
                            <literallayout class='monospaced'>
     ssh test@10.11.12.1 "pyctl nuc1 &lt;arg&gt;"
                            </literallayout>
                            It then runs a Python script that controls power
                            for a label called <filename>nuc1</filename>.
                            <note>
                                You need to customize
                                <filename>TEST_POWERCONTROL_CMD</filename>
                                and
                                <filename>TEST_POWERCONTROL_EXTRA_ARGS</filename>
                                for your own setup.
                                The one requirement is that it accepts
                                "on", "off", and "cycle" as the last argument.
                            </note>
                            </para></listitem>
                        <listitem><para>
                            When no command is defined, it connects to the
                            device over SSH and uses the classic reboot command
                            to reboot the device.
                            Classic reboot is fine as long as the machine
                            actually reboots (i.e. the SSH test has not
                            failed).
                            It is useful for scenarios where you have a simple
                            setup, typically with a single board, and where
                            some manual interaction is okay from time to time.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </section>
        </section>

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

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

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

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

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

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

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

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

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

            <para>
                If you image is already built, make sure the following are set
                in your <filename>local.conf</filename> file.
                Be sure to provide the IP address you need:
                <literallayout class='monospaced'>
     TEST_EXPORT_ONLY = "1"
     TEST_TARGET = "simpleremote"
     TEST_TARGET_IP = "192.168.7.2"
     TEST_SERVER_IP = "192.168.7.1"
                </literallayout>
                You can then export the tests with the following:
                <literallayout class='monospaced'>
     $ bitbake core-image-sato -c testimage
                </literallayout>
                Exporting the tests places them in the
                <link linkend='build-directory'>Build Directory</link> in
                <filename>tmp/testimage/core-image-sato</filename>, which
                is controlled by the
                <filename>TEST_EXPORT_DIR</filename> variable.
            </para>

            <para>
                The exported data (i.e. <filename>testdata.json</filename>)
                contains paths to the Build Directory.
                Thus, the contents of the directory can be moved
                to another machine as long as you update some paths in the
                JSON.
                Usually you only care about the
                ${DEPLOY_DIR}/rpm directory (assuming the RPM and Smart tests
                are enabled).
                Consequently, running the tests on other machine
                means that you have to move the contents and call
                <filename>runexported</filename> with "--deploy-dir PATH:
                ./runexported.py --deploy-dir /new/path/on/this/machine testdata.json
                runexported.py accepts other arguments as well, see --help.
            </para>

            <para>
                You can now run the tests outside of the build environment:
                <literallayout class='monospaced'>
     $ cd tmp/testimage/core-image-sato
     $ ./runexported.py testdata.json
                </literallayout>
                <note>
                    This "export" feature does not deploy or boot the target
                    image.
                    Your target (be it a Qemu or hardware one)
                    has to already be up and running when you call
                    <filename>runexported.py</filename>
                </note>
            </para>
        </section>

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

            <para>
                As mentioned previously, all new test files need to be in the
                proper place for the build system to find them.
                New tests for additional functionality outside of the core
                should be added to the layer that adds the functionality, in
                <filename>&lt;layer&gt;/lib/oeqa/runtime</filename> (as
                long as
                <ulink url='&YOCTO_DOCS_REF_URL;#var-BBPATH'><filename>BBPATH</filename></ulink>
                is extended in the layer's
                <filename>layer.conf</filename> file as normal).
                Just remember that filenames need to map directly to test
                (module) names and that you do not use module names that
                collide with existing core tests.
            </para>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        <para>
            The remainder of this section describes the steps you need to take
            to debug using the GNU project debugger.
        </para>

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

            <para>
                Before you can initiate a remote debugging session, you need
                to be sure you have set up the cross-development environment,
                toolchain, and sysroot.
                The "<ulink url='&YOCTO_DOCS_ADT_URL;#adt-prepare'>Preparing for Application Development</ulink>"
                chapter of the Yocto Project Application Developer's Guide
                describes this process.
                Be sure you have read that chapter and have set up
                your environment.
            </para>
        </section>

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

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

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

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

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

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

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

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

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

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

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

                <para>
                    Before launching the host GDB, you need to be sure
                    you have sourced the cross-debugging environment script,
                    which if you installed the root filesystem in the default
                    location is at <filename>/opt/poky/&DISTRO;</filename>
                    and begins with the string "environment-setup".
                    For more information, see the
                    "<ulink url='&YOCTO_DOCS_ADT_URL;#setting-up-the-cross-development-environment'>Setting Up the Cross-Development Environment</ulink>"
                    section in the Yocto Project Application Developer's
                    Guide.
                </para>

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

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

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

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

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

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

    <section id="examining-builds-using-toaster">
        <title>Examining Builds Using the Toaster API</title>

        <para>
            Toaster is an Application Programming Interface (API) and
            web-based interface to the OpenEmbedded build system, which uses
            BitBake.
            Both interfaces are based on a Representational State Transfer
            (REST) API that queries for and returns build information using
            <filename>GET</filename> and <filename>JSON</filename>.
            These types of search operations retrieve sets of objects from
            a datastore used to collect build information.
            The results contain all the data for the objects being returned.
            You can order the results of the search by key and the search
            parameters are consistent for all object types.
        </para>

        <para>
            Using the interfaces you can do the following:
            <itemizedlist>
                <listitem><para>See information about the tasks executed
                    and reused during the build.</para></listitem>
                <listitem><para>See what is built (recipes and
                    packages) and what packages were installed into the final
                    image.</para></listitem>
                <listitem><para>See performance-related information such
                    as build time, CPU usage, and disk I/O.</para></listitem>
                <listitem><para>Examine error, warning and trace messages
                    to aid in debugging.</para></listitem>
            </itemizedlist>
        </para>

        <note>
            <para>This release of Toaster provides you with information
            about a BitBake run.
            The tool does not allow you to configure and launch a build.
            However, future development includes plans to integrate the
            configuration and build launching capabilities of
            <ulink url='&YOCTO_HOME_URL;/tools-resources/projects/hob'>Hob</ulink>.
            </para>
            <para>For more information on using Hob to build an image,
            see the
            "<link linkend='image-development-using-hob'>Image Development Using Hob</link>"
            section.</para>
        </note>

        <para>
            The remainder of this section describes what you need to have in
            place to use Toaster, how to start it, use it, and stop it.
            For additional information on installing and running Toaster, see the
            "<ulink url='https://wiki.yoctoproject.org/wiki/Toaster#Installation_and_Running'>Installation and Running</ulink>"
            section of the "Toaster" wiki page.
            For complete information on the API and its search operation
            URI, parameters, and responses, see the
            <ulink url='https://wiki.yoctoproject.org/wiki/REST_API_Contracts'>REST API Contracts</ulink>
            Wiki page.
        </para>

        <section id='starting-toaster'>
            <title>Starting Toaster</title>

            <para>
                Getting set up to use and start Toaster is simple.
                First, be sure you have met the following requirements:
                <itemizedlist>
                    <listitem><para>You have set up your
                        <link linkend='source-directory'>Source Directory</link>
                        by cloning the upstream <filename>poky</filename>
                        repository.
                        See the
                        <link linkend='local-yp-release'>Yocto Project Release</link>
                        item for information on how to set up the Source
                        Directory.</para></listitem>
                    <listitem><para>Be sure your build machine has
                        <ulink url='http://en.wikipedia.org/wiki/Django_%28web_framework%29'>Django</ulink>
                        version 1.5 installed.</para></listitem>
                    <listitem><para>Make sure that port 8000 and 8200 are
                        free (i.e. they have no servers on them).
                        </para></listitem>
                </itemizedlist>
            </para>

            <para>
                Once you have met the requirements, follow these steps to
                start Toaster running in the background of your shell:
                <orderedlist>
                    <listitem><para><emphasis>Set up your build environment:</emphasis>
                        Source a build environment script (i.e.
                        <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink>
                        or
                        <ulink url='&YOCTO_DOCS_REF_URL;#structure-memres-core-script'><filename>oe-init-build-env-memres</filename></ulink>).
                        </para></listitem>
                    <listitem><para><emphasis>Start Toaster:</emphasis>
                        Start the Toaster service using this
                        command from within your
                        <link linkend='build-directory'>Build Directory</link>:
                        <literallayout class='monospaced'>
     $ source toaster start
                        </literallayout></para></listitem>
                        <note>
                            The Toaster must be started and running in order
                            for it to collect data.
                        </note>
                </orderedlist>
            </para>

            <para>
                When Toaster starts, it creates some additional files in your
                Build Directory.
                Deleting these files will cause you to lose data or interrupt
                Toaster:
                <itemizedlist>
                    <listitem><para><emphasis><filename>toaster.sqlite</filename>:</emphasis>
                        Toaster's database file.</para></listitem>
                    <listitem><para><emphasis><filename>toaster_web.log</filename>:</emphasis>
                        The log file of the web server.</para></listitem>
                    <listitem><para><emphasis><filename>toaster_ui.log</filename>:</emphasis>
                        The log file of the user interface component.
                        </para></listitem>
                    <listitem><para><emphasis><filename>toastermain.pid</filename>:</emphasis>
                        The PID of the web server.</para></listitem>
                    <listitem><para><emphasis><filename>toasterui.pid</filename>:</emphasis>
                        The PID of the DSI data bridge.</para></listitem>
                    <listitem><para><emphasis><filename>bitbake-cookerdaemon.log</filename>:</emphasis>
                        The BitBake server's log file.</para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='using-toaster'>
            <title>Using Toaster</title>

            <para>
                Once Toaster is running, it logs information for any BitBake
                run from your Build Directory.
                This logging is automatic.
                All you need to do is access and use the information.
            </para>

            <para>
                You access the information one of two ways:
                <itemizedlist>
                    <listitem><para>Open a Browser and enter
                        <filename>http://localhost:8000</filename>
                        for the URL.
                        </para></listitem>
                    <listitem><para>Use the <filename>xdg-open</filename>
                        tool from the shell and pass it the same URL.
                        </para></listitem>
                </itemizedlist>
                Either method opens the home page for the Toaster interface.
            </para>

            <note><title>Notes</title>
                <para>
                    For information on how to delete information from the Toaster
                    database, see the
                    <ulink url='https://wiki.yoctoproject.org/wiki/Toaster#Deleting_a_Build_from_the_Toaster_Database'>Deleting a Build from the Toaster Database</ulink>
                    wiki page.
                </para>

                <para>
                    For information on how to set up an instance of Toaster on
                    a remote host, see the
                    <ulink url='https://wiki.yoctoproject.org/wiki/Toaster#Setting_up_a_Toaster_Instance_on_a_Remote_Host'>Setting Up a Toaster Instance on a Remote Host</ulink>
                    wiki page.
                </para>
            </note>
        </section>

        <section id='examining-toaster-data'>
            <title>Examining Toaster Data</title>

            <para>
                The Toaster database is persistent regardless of whether you
                start or stop the service.
            </para>

            <para>
                Toaster's interface shows you a list of builds
                (successful and unsuccessful) for which it has data.
                You can click on any build to see related information.
                This information includes configuration details, information
                about tasks, all recipes and packages built and their
                dependencies, packages and their directory structure as
                installed in your final image,
                execution time, CPU usage and disk I/O per task.
            </para>

            <para>
                For details on the interface, see the
                <ulink url='https://www.yoctoproject.org/documentation/toaster-manual'>Toaster Manual</ulink>.
            </para>
        </section>

        <section id='stopping-toaster'>
            <title>Stopping Toaster</title>

            <para>
                Stop the Toaster service with the following command
                from with the
                <link linkend='build-directory'>Build Directory</link>:
                <literallayout class='monospaced'>
     $ source toaster stop
                </literallayout>
                The service stops but the Toaster database remains persistent.
            </para>
        </section>
    </section>

    <section id="platdev-oprofile">
        <title>Profiling with OProfile</title>

        <para>
            <ulink url="http://oprofile.sourceforge.net/">OProfile</ulink> is a
            statistical profiler well suited for finding performance
            bottlenecks in both user-space software and in the kernel.
            This profiler provides answers to questions like "Which functions does my application spend
            the most time in when doing X?"
            Because the OpenEmbedded build system is well integrated with OProfile, it makes profiling
            applications on target hardware straight forward.
            <note>
                For more information on how to set up and run OProfile, see the
                "<ulink url='&YOCTO_DOCS_PROF_URL;#profile-manual-oprofile'>oprofile</ulink>"
                section in the Yocto Project Profiling and Tracing Manual.
            </note>
        </para>

        <para>
            To use OProfile, you need an image that has OProfile installed.
            The easiest way to do this is with "tools-profile" in the
            <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'>IMAGE_FEATURES</ulink></filename> variable.
            You also need debugging symbols to be available on the system where the analysis
            takes place.
            You can gain access to the symbols by using "dbg-pkgs" in the
            <filename>IMAGE_FEATURES</filename> variable or by
            installing the appropriate DBG (<filename>-dbg</filename>) packages.
        </para>

        <para>
            For successful call graph analysis, the binaries must preserve the frame
            pointer register and should also be compiled with the
            <filename>-fno-omit-framepointer</filename> flag.
            You can achieve this by setting the
            <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SELECTED_OPTIMIZATION'>SELECTED_OPTIMIZATION</ulink></filename>
            variable with the following options:
            <literallayout class='monospaced'>
     -fexpensive-optimizations
     -fno-omit-framepointer
     -frename-registers
     -O2
            </literallayout>
            You can also achieve it by setting the
            <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-DEBUG_BUILD'>DEBUG_BUILD</ulink></filename>
            variable to "1" in the <filename>local.conf</filename> configuration file.
            If you use the <filename>DEBUG_BUILD</filename> variable,
            you also add extra debugging information that can make the debug
            packages large.
        </para>

        <section id="platdev-oprofile-target">
            <title>Profiling on the Target</title>

            <para>
                Using OProfile, you can perform all the profiling work on the target device.
                A simple OProfile session might look like the following:
            </para>

            <para>
                <literallayout class='monospaced'>
     # opcontrol --reset
     # opcontrol --start --separate=lib --no-vmlinux -c 5
              .
              .
        [do whatever is being profiled]
              .
              .
     # opcontrol --stop
     $ opreport -cl
                </literallayout>
            </para>

            <para>
                In this example, the <filename>reset</filename> command clears any previously profiled data.
                The next command starts OProfile.
                The options used when starting the profiler separate dynamic library data
                within applications, disable kernel profiling, and enable callgraphing up to
                five levels deep.
                <note>
                    To profile the kernel, you would specify the
                    <filename>--vmlinux=/path/to/vmlinux</filename> option.
                    The <filename>vmlinux</filename> file is usually in the source directory in the
                    <filename>/boot/</filename> directory and must match the running kernel.
                </note>
            </para>

            <para>
                After you perform your profiling tasks, the next command stops the profiler.
                After that, you can view results with the <filename>opreport</filename> command with options
                to see the separate library symbols and callgraph information.
            </para>

            <para>
                Callgraphing logs information about time spent in functions and about a function's
                calling function (parent) and called functions (children).
                The higher the callgraphing depth, the more accurate the results.
                However, higher depths also increase the logging overhead.
                Consequently, you should take care when setting the callgraphing depth.
                <note>
                    On ARM, binaries need to have the frame pointer enabled for callgraphing to work.
                    To accomplish this use the <filename>-fno-omit-framepointer</filename> option
                    with <filename>gcc</filename>.
                </note>
            </para>

            <para>
                For more information on using OProfile, see the OProfile
                online documentation at
                <ulink url="http://oprofile.sourceforge.net/docs/"/>.
            </para>
        </section>

        <section id="platdev-oprofile-oprofileui">
            <title>Using OProfileUI</title>

            <para>
                A graphical user interface for OProfile is also available.
                You can download and build this interface from the Yocto Project at
                <ulink url="&YOCTO_GIT_URL;/cgit.cgi/oprofileui/"></ulink>.
                If the "tools-profile" image feature is selected, all necessary binaries
                are installed onto the target device for OProfileUI interaction.
                For a list of image features that ship with the Yocto Project,
                see the
                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-features-image'>Image Features</ulink>"
                section in the Yocto Project Reference Manual.
            </para>

            <para>
                Even though the source directory usually includes all needed patches on the target device, you
                might find you need other OProfile patches for recent OProfileUI features.
                If so, see the <ulink url='&YOCTO_GIT_URL;/cgit.cgi/oprofileui/tree/README'>
                OProfileUI README</ulink> for the most recent information.
            </para>

            <section id="platdev-oprofile-oprofileui-online">
                <title>Online Mode</title>

                <para>
                    Using OProfile in online mode assumes a working network connection with the target
                    hardware.
                    With this connection, you just need to run "oprofile-server" on the device.
                    By default, OProfile listens on port 4224.
                    <note>
                        You can change the port using the <filename>--port</filename> command-line
                        option.
                    </note>
                </para>

                <para>
                    The client program is called <filename>oprofile-viewer</filename> and its UI is relatively
                    straight forward.
                    You access key functionality through the buttons on the toolbar, which
                    are duplicated in the menus.
                    Here are the buttons:
                    <itemizedlist>
                        <listitem><para><emphasis>Connect:</emphasis> Connects to the remote host.
                            You can also supply the IP address or hostname.</para></listitem>
                        <listitem><para><emphasis>Disconnect:</emphasis> Disconnects from the target.
                            </para></listitem>
                        <listitem><para><emphasis>Start:</emphasis> Starts profiling on the device.
                            </para></listitem>
                        <listitem><para><emphasis>Stop:</emphasis> Stops profiling on the device and
                            downloads the data to the local host.
                            Stopping the profiler generates the profile and displays it in the viewer.
                            </para></listitem>
                        <listitem><para><emphasis>Download:</emphasis> Downloads the data from the
                            target and generates the profile, which appears in the viewer.</para></listitem>
                        <listitem><para><emphasis>Reset:</emphasis> Resets the sample data on the device.
                            Resetting the data removes sample information collected from previous
                            sampling runs.
                            Be sure you reset the data if you do not want to include old sample information.
                            </para></listitem>
                        <listitem><para><emphasis>Save:</emphasis> Saves the data downloaded from the
                            target to another directory for later examination.</para></listitem>
                        <listitem><para><emphasis>Open:</emphasis> Loads previously saved data.
                            </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    The client downloads the complete profile archive from
                    the target to the host for processing.
                    This archive is a directory that contains the sample data, the object files,
                    and the debug information for the object files.
                    The archive is then converted using the <filename>oparchconv</filename> script, which is
                    included in this distribution.
                    The script uses <filename>opimport</filename> to convert the archive from
                    the target to something that can be processed on the host.
                </para>

                <para>
                    Downloaded archives reside in the
                    <link linkend='build-directory'>Build Directory</link> in
                    <filename>tmp</filename> and are cleared up when they are no longer in use.
                </para>

                <para>
                    If you wish to perform kernel profiling, you need to be sure
                    a <filename>vmlinux</filename> file that matches the running kernel is available.
                    In the source directory, that file is usually located in
                    <filename>/boot/vmlinux-KERNELVERSION</filename>, where
                    <filename>KERNEL-version</filename> is the version of the kernel.
                    The OpenEmbedded build system generates separate <filename>vmlinux</filename>
                    packages for each kernel it builds.
                    Thus, it should just be a question of making sure a matching package is
                    installed (e.g. <filename>opkg install kernel-vmlinux</filename>).
                    The files are automatically installed into development and profiling images
                    alongside OProfile.
                    A configuration option exists within the OProfileUI settings page that you can use to
                    enter the location of the <filename>vmlinux</filename> file.
                </para>

                <para>
                    Waiting for debug symbols to transfer from the device can be slow, and it
                    is not always necessary to actually have them on the device for OProfile use.
                    All that is needed is a copy of the filesystem with the debug symbols present
                    on the viewer system.
                    The "<link linkend='platdev-gdb-remotedebug-launch-gdb'>Launch GDB on the Host Computer</link>"
                    section covers how to create such a directory within
                    the source directory and how to use the OProfileUI Settings
                    Dialog to specify the location.
                    If you specify the directory, it will be used when the file checksums
                    match those on the system you are profiling.
                </para>
            </section>

            <section id="platdev-oprofile-oprofileui-offline">
                <title>Offline Mode</title>

                <para>
                    If network access to the target is unavailable, you can generate
                    an archive for processing in <filename>oprofile-viewer</filename> as follows:
                    <literallayout class='monospaced'>
     # opcontrol --reset
     # opcontrol --start --separate=lib --no-vmlinux -c 5
            .
            .
     [do whatever is being profiled]
            .
            .
     # opcontrol --stop
     # oparchive -o my_archive
                    </literallayout>
                </para>

                <para>
                    In the above example, <filename>my_archive</filename> is the name of the
                    archive directory where you would like the profile archive to be kept.
                    After the directory is created, you can copy it to another host and load it
                    using <filename>oprofile-viewer</filename> open functionality.
                    If necessary, the archive is converted.
                </para>
            </section>
        </section>
    </section>

    <section id='maintaining-open-source-license-compliance-during-your-products-lifecycle'>
        <title>Maintaining Open Source License Compliance During Your Product's Lifecycle</title>

        <para>
            One of the concerns for a development organization using open source
            software is how to maintain compliance with various open source
            licensing during the lifecycle of the product.
            While this section does not provide legal advice or
            comprehensively cover all scenarios, it does
            present methods that you can use to
            assist you in meeting the compliance requirements during a software
            release.
        </para>

        <para>
            With hundreds of different open source licenses that the Yocto
            Project tracks, it is difficult to know the requirements of each
            and every license.
            However, the requirements of the major FLOSS licenses can begin
            to be covered by
            assuming that three main areas of concern exist:
            <itemizedlist>
                <listitem><para>Source code must be provided.</para></listitem>
                <listitem><para>License text for the software must be
                    provided.</para></listitem>
                <listitem><para>Compilation scripts and modifications to the
                    source code must be provided.
                    </para></listitem>
            </itemizedlist>
            There are other requirements beyond the scope of these
            three and the methods described in this section
            (e.g. the mechanism through which source code is distributed).
        </para>

        <para>
            As different organizations have different methods of complying with
            open source licensing, this section is not meant to imply that
            there is only one single way to meet your compliance obligations,
            but rather to describe one method of achieving compliance.
            The remainder of this section describes methods supported to meet the
            previously mentioned three requirements.
            Once you take steps to meet these requirements,
            and prior to releasing images, sources, and the build system,
            you should audit all artifacts to ensure completeness.
            <note>
                The Yocto Project generates a license manifest during
                image creation that is located
                in <filename>${DEPLOY_DIR}/licenses/&lt;image_name-datestamp&gt;</filename>
                to assist with any audits.
            </note>
        </para>

        <section id='providing-the-source-code'>
            <title>Providing the Source Code</title>

            <para>
                Compliance activities should begin before you generate the
                final image.
                The first thing you should look at is the requirement that
                tops the list for most compliance groups - providing
                the source.
                The Yocto Project has a few ways of meeting this
                requirement.
            </para>

            <para>
                One of the easiest ways to meet this requirement is
                to provide the entire
                <ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'><filename>DL_DIR</filename></ulink>
                used by the build.
                This method, however, has a few issues.
                The most obvious is the size of the directory since it includes
                all sources used in the build and not just the source used in
                the released image.
                It will include toolchain source, and other artifacts, which
                you would not generally release.
                However, the more serious issue for most companies is accidental
                release of proprietary software.
                The Yocto Project provides an
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-archiver'><filename>archiver</filename></ulink>
                class to help avoid some of these concerns.
            </para>

            <para>
                Before you employ <filename>DL_DIR</filename> or the
                archiver class, you need to decide how you choose to
                provide source.
                The source archiver class can generate tarballs and SRPMs
                and can create them with various levels of compliance in mind.
            </para>

            <para>
                One way of doing this (but certainly not the only way) is to
                release just the source as a tarball.
                You can do this by adding the following to the
                <filename>local.conf</filename> file found in the
                <link linkend='build-directory'>Build Directory</link>:
                <literallayout class='monospaced'>
     INHERIT += "archiver"
     ARCHIVER_MODE[src] = "original"
                </literallayout>
                During the creation of your image, the source from all
                recipes that deploy packages to the image is placed within
                subdirectories of
                <filename>DEPLOY_DIR/sources</filename> based on the
                <ulink url='&YOCTO_DOCS_REF_URL;#var-LICENSE'><filename>LICENSE</filename></ulink>
                for each recipe.
                Releasing the entire directory enables you to comply with
                requirements concerning providing the unmodified source.
                It is important to note that the size of the directory can
                get large.
            </para>

            <para>
                A way to help mitigate the size issue is to only release
                tarballs for licenses that require the release of
                source.
                Let us assume you are only concerned with GPL code as
                identified with the following:
                <literallayout class='monospaced'>
     $ cd poky/build/tmp/deploy/sources
     $ mkdir ~/gpl_source_release
     $ for dir in */*GPL*; do cp -r $dir ~/gpl_source_release; done
                </literallayout>
                At this point, you could create a tarball from the
                <filename>gpl_source_release</filename> directory and
                provide that to the end user.
                This method would be a step toward achieving compliance
                with section 3a of GPLv2 and with section 6 of GPLv3.
            </para>
        </section>

        <section id='providing-license-text'>
            <title>Providing License Text</title>

            <para>
                One requirement that is often overlooked is inclusion
                of license text.
                This requirement also needs to be dealt with prior to
                generating the final image.
                Some licenses require the license text to accompany
                the binary.
                You can achieve this by adding the following to your
                <filename>local.conf</filename> file:
                <literallayout class='monospaced'>
     COPY_LIC_MANIFEST = "1"
     COPY_LIC_DIRS = "1"
                </literallayout>
                Adding these statements to the configuration file ensures
                that the licenses collected during package generation
                are included on your image.
                As the source archiver has already archived the original
                unmodified source that contains the license files,
                you would have already met the requirements for inclusion
                of the license information with source as defined by the GPL
                and other open source licenses.
            </para>
        </section>

        <section id='providing-compilation-scripts-and-source-code-modifications'>
            <title>Providing Compilation Scripts and Source Code Modifications</title>

            <para>
                At this point, we have addressed all we need to address
                prior to generating the image.
                The next two requirements are addressed during the final
                packaging of the release.
            </para>

            <para>
                By releasing the version of the OpenEmbedded build system
                and the layers used during the build, you will be providing both
                compilation scripts and the source code modifications in one
                step.
            </para>

            <para>
                If the deployment team has a
                <ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP layer</ulink>
                and a distro layer, and those those layers are used to patch,
                compile, package, or modify (in any way) any open source
                software included in your released images, you
                might be required to to release those layers under section 3 of
                GPLv2 or section 1 of GPLv3.
                One way of doing that is with a clean
                checkout of the version of the Yocto Project and layers used
                during your build.
                Here is an example:
                <literallayout class='monospaced'>
     # We built using the &DISTRO_NAME; branch of the poky repo
     $ git clone -b &DISTRO_NAME; git://git.yoctoproject.org/poky
     $ cd poky
     # We built using the release_branch for our layers
     $ git clone -b release_branch git://git.mycompany.com/meta-my-bsp-layer
     $ git clone -b release_branch git://git.mycompany.com/meta-my-software-layer
     # clean up the .git repos
     $ find . -name ".git" -type d -exec rm -rf {} \;
                </literallayout>
                One thing a development organization might want to consider
                for end-user convenience is to modify
                <filename>meta-yocto/conf/bblayers.conf.sample</filename> to
                ensure that when the end user utilizes the released build
                system to build an image, the development organization's
                layers are included in the <filename>bblayers.conf</filename>
                file automatically:
                <literallayout class='monospaced'>
     # LAYER_CONF_VERSION is increased each time build/conf/bblayers.conf
     # changes incompatibly
     LCONF_VERSION = "6"

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

     BBLAYERS ?= " \
       ##OEROOT##/meta \
       ##OEROOT##/meta-yocto \
       ##OEROOT##/meta-yocto-bsp \
       ##OEROOT##/meta-mylayer \
       "

     BBLAYERS_NON_REMOVABLE ?= " \
       ##OEROOT##/meta \
       ##OEROOT##/meta-yocto \
       "
                </literallayout>
                Creating and providing an archive of the
                <link linkend='metadata'>Metadata</link> layers
                (recipes, configuration files, and so forth)
                enables you to meet your
                requirements to include the scripts to control compilation
                as well as any modifications to the original source.
            </para>
        </section>
    </section>

    <section id='using-the-error-reporting-tool'>
        <title>Using the Error Reporting Tool</title>

        <para>
            The error reporting tool allows you to
            submit errors encountered during builds to a central database.
            Outside of the build environment, you can use a web interface to
            browse errors, view statistics, and query for errors.
            The tool works using a client-server system where the client
            portion is integrated with the installed Yocto Project
            <link linkend='source-directory'>Source Directory</link>
            (e.g. <filename>poky</filename>).
            The server receives the information collected and saves it in a
            database.
        </para>

        <para>
            A live instance of the error reporting server exists at
            <ulink url='http://errors.yoctoproject.org'></ulink>.
            This server exists so that when you want to get help with
            build failures, you can submit all of the information on the
            failure easily and then point to the URL in your bug report
            or send an email to the mailing list.
            <note>
                If you send error reports to this server, the reports become
                publicly visible.
            </note>
        </para>

        <section id='enabling-and-using-the-tool'>
            <title>Enabling and Using the Tool</title>

            <para>
                By default, the error reporting tool is disabled.
                You can enable it by inheriting the
                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-report-error'><filename>report-error</filename></ulink>
                class by adding the following statement to the end of
                your <filename>local.conf</filename> file in your
                <link linkend='build-directory'>Build Directory</link>.
                <literallayout class='monospaced'>
     INHERIT += "report-error"
                </literallayout>
            </para>

            <para>
                By default, the error reporting feature stores information in
                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LOG_DIR'><filename>LOG_DIR</filename></ulink><filename>}/error-report</filename>.
                However, you can specify a directory to use by adding the following
                to your <filename>local.conf</filename> file:
                <literallayout class='monospaced'>
     ERR_REPORT_DIR = "path"
                </literallayout>
                Enabling error reporting causes the build process to collect
                the errors and store them in a file as previously described.
                When the build system encounters an error, it includes a command
                as part of the console output.
                You can run the command to send the error file to the server.
                For example, the following command sends the errors to an upstream
                server:
                <literallayout class='monospaced'>
     send-error-report /home/brandusa/project/poky/build/tmp/log/error-report/error_report_201403141617.txt [server]
                </literallayout>
                In the above example, the <filename>server</filename> parameter is
                optional.
                By default, the errors are sent to a database used by the entire
                community.
                If you specify a particular server, you can send them to a different
                database.
            </para>

            <para>
                When sending the error file, you receive a link that corresponds
                to your entry in the database.
                For example, here is a typical link:
                <literallayout class='monospaced'>
     http://localhost:8000/Errors/Search/1/158
                </literallayout>
                Following the link takes you to a web interface where you can
                browse, query the errors, and view statistics.
             </para>
        </section>

        <section id='disabling-the-tool'>
            <title>Disabling the Tool</title>

            <para>
                To disable the error reporting feature, simply remove or comment
                out the following statement from the end of your
                <filename>local.conf</filename> file in your
                <link linkend='build-directory'>Build Directory</link>.
                <literallayout class='monospaced'>
     INHERIT += "report-error"
                </literallayout>
            </para>
        </section>

        <section id='setting-up-your-own-error-reporting-server'>
            <title>Setting Up Your Own Error Reporting Server</title>

            <para>
                If you want to set up your own error reporting server, you
                can obtain the code from the Git repository at
                <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi/error-report-web/'></ulink>.
                Instructions on how to set it up are in the README document.
            </para>
        </section>
     </section>
</chapter>

<!--
vim: expandtab tw=80 ts=4
-->