aboutsummaryrefslogtreecommitdiff
path: root/qemu-doc.texi
blob: 3ddf5c0a686570a43ef94cdd1fbe482e40555ab6 (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
\input texinfo @c -*- texinfo -*-
@c %**start of header
@setfilename qemu-doc.info
@include version.texi

@documentlanguage en
@documentencoding UTF-8

@settitle QEMU version @value{VERSION} User Documentation
@exampleindent 0
@paragraphindent 0
@c %**end of header

@set qemu_system qemu-system-x86_64
@set qemu_system_x86 qemu-system-x86_64

@ifinfo
@direntry
* QEMU: (qemu-doc).    The QEMU Emulator User Documentation.
@end direntry
@end ifinfo

@iftex
@titlepage
@sp 7
@center @titlefont{QEMU version @value{VERSION}}
@sp 1
@center @titlefont{User Documentation}
@sp 3
@end titlepage
@end iftex

@ifnottex
@node Top
@top

@menu
* Introduction::
* QEMU PC System emulator::
* QEMU System emulator for non PC targets::
* QEMU Guest Agent::
* QEMU User space emulator::
* System requirements::
* Security::
* Implementation notes::
* Deprecated features::
* Recently removed features::
* Supported build platforms::
* License::
* Index::
@end menu
@end ifnottex

@contents

@node Introduction
@chapter Introduction

@menu
* intro_features:: Features
@end menu

@node intro_features
@section Features

QEMU is a FAST! processor emulator using dynamic translation to
achieve good emulation speed.

@cindex operating modes
QEMU has two operating modes:

@itemize
@cindex system emulation
@item Full system emulation. In this mode, QEMU emulates a full system (for
example a PC), including one or several processors and various
peripherals. It can be used to launch different Operating Systems
without rebooting the PC or to debug system code.

@cindex user mode emulation
@item User mode emulation. In this mode, QEMU can launch
processes compiled for one CPU on another CPU. It can be used to
launch the Wine Windows API emulator (@url{https://www.winehq.org}) or
to ease cross-compilation and cross-debugging.

@end itemize

QEMU has the following features:

@itemize
@item QEMU can run without a host kernel driver and yet gives acceptable
performance.  It uses dynamic translation to native code for reasonable speed,
with support for self-modifying code and precise exceptions.

@item It is portable to several operating systems (GNU/Linux, *BSD, Mac OS X,
Windows) and architectures.

@item It performs accurate software emulation of the FPU.
@end itemize

QEMU user mode emulation has the following features:
@itemize
@item Generic Linux system call converter, including most ioctls.

@item clone() emulation using native CPU clone() to use Linux scheduler for threads.

@item Accurate signal handling by remapping host signals to target signals.
@end itemize

QEMU full system emulation has the following features:
@itemize
@item
QEMU uses a full software MMU for maximum portability.

@item
QEMU can optionally use an in-kernel accelerator, like kvm. The accelerators
execute most of the guest code natively, while
continuing to emulate the rest of the machine.

@item
Various hardware devices can be emulated and in some cases, host
devices (e.g. serial and parallel ports, USB, drives) can be used
transparently by the guest Operating System. Host device passthrough
can be used for talking to external physical peripherals (e.g. a
webcam, modem or tape drive).

@item
Symmetric multiprocessing (SMP) support.  Currently, an in-kernel
accelerator is required to use more than one host CPU for emulation.

@end itemize


@node QEMU PC System emulator
@chapter QEMU PC System emulator
@cindex system emulation (PC)

@menu
* pcsys_introduction:: Introduction
* pcsys_quickstart::   Quick Start
* sec_invocation::     Invocation
* pcsys_keys::         Keys in the graphical frontends
* mux_keys::           Keys in the character backend multiplexer
* pcsys_monitor::      QEMU Monitor
* cpu_models::         CPU models
* disk_images::        Disk Images
* pcsys_network::      Network emulation
* pcsys_other_devs::   Other Devices
* direct_linux_boot::  Direct Linux Boot
* pcsys_usb::          USB emulation
* vnc_security::       VNC security
* network_tls::        TLS setup for network services
* gdb_usage::          GDB usage
* pcsys_os_specific::  Target OS specific information
@end menu

@node pcsys_introduction
@section Introduction

@c man begin DESCRIPTION

The QEMU PC System emulator simulates the
following peripherals:

@itemize @minus
@item
i440FX host PCI bridge and PIIX3 PCI to ISA bridge
@item
Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA
extensions (hardware level, including all non standard modes).
@item
PS/2 mouse and keyboard
@item
2 PCI IDE interfaces with hard disk and CD-ROM support
@item
Floppy disk
@item
PCI and ISA network adapters
@item
Serial ports
@item
IPMI BMC, either and internal or external one
@item
Creative SoundBlaster 16 sound card
@item
ENSONIQ AudioPCI ES1370 sound card
@item
Intel 82801AA AC97 Audio compatible sound card
@item
Intel HD Audio Controller and HDA codec
@item
Adlib (OPL2) - Yamaha YM3812 compatible chip
@item
Gravis Ultrasound GF1 sound card
@item
CS4231A compatible sound card
@item
PCI UHCI, OHCI, EHCI or XHCI USB controller and a virtual USB-1.1 hub.
@end itemize

SMP is supported with up to 255 CPUs.

QEMU uses the PC BIOS from the Seabios project and the Plex86/Bochs LGPL
VGA BIOS.

QEMU uses YM3812 emulation by Tatsuyuki Satoh.

QEMU uses GUS emulation (GUSEMU32 @url{http://www.deinmeister.de/gusemu/})
by Tibor "TS" Schütz.

Note that, by default, GUS shares IRQ(7) with parallel ports and so
QEMU must be told to not have parallel ports to have working GUS.

@example
@value{qemu_system_x86} dos.img -soundhw gus -parallel none
@end example

Alternatively:
@example
@value{qemu_system_x86} dos.img -device gus,irq=5
@end example

Or some other unclaimed IRQ.

CS4231A is the chip used in Windows Sound System and GUSMAX products

@c man end

@node pcsys_quickstart
@section Quick Start
@cindex quick start

Download and uncompress a hard disk image with Linux installed (e.g.
@file{linux.img}) and type:

@example
@value{qemu_system} linux.img
@end example

Linux should boot and give you a prompt.

@node sec_invocation
@section Invocation

@example
@c man begin SYNOPSIS
@command{@value{qemu_system}} [@var{options}] [@var{disk_image}]
@c man end
@end example

@c man begin OPTIONS
@var{disk_image} is a raw hard disk image for IDE hard disk 0. Some
targets do not need a disk image.

@include qemu-options.texi

@c man end

@subsection Device URL Syntax
@c TODO merge this with section Disk Images

@c man begin NOTES

In addition to using normal file images for the emulated storage devices,
QEMU can also use networked resources such as iSCSI devices. These are
specified using a special URL syntax.

@table @option
@item iSCSI
iSCSI support allows QEMU to access iSCSI resources directly and use as
images for the guest storage. Both disk and cdrom images are supported.

Syntax for specifying iSCSI LUNs is
``iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>''

By default qemu will use the iSCSI initiator-name
'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from the command
line or a configuration file.

Since version Qemu 2.4 it is possible to specify a iSCSI request timeout to detect
stalled requests and force a reestablishment of the session. The timeout
is specified in seconds. The default is 0 which means no timeout. Libiscsi
1.15.0 or greater is required for this feature.

Example (without authentication):
@example
@value{qemu_system} -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \
                 -cdrom iscsi://192.0.2.1/iqn.2001-04.com.example/2 \
                 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
@end example

Example (CHAP username/password via URL):
@example
@value{qemu_system} -drive file=iscsi://user%password@@192.0.2.1/iqn.2001-04.com.example/1
@end example

Example (CHAP username/password via environment variables):
@example
LIBISCSI_CHAP_USERNAME="user" \
LIBISCSI_CHAP_PASSWORD="password" \
@value{qemu_system} -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
@end example

@item NBD
QEMU supports NBD (Network Block Devices) both using TCP protocol as well
as Unix Domain Sockets.  With TCP, the default port is 10809.

Syntax for specifying a NBD device using TCP, in preferred URI form:
``nbd://<server-ip>[:<port>]/[<export>]''

Syntax for specifying a NBD device using Unix Domain Sockets; remember
that '?' is a shell glob character and may need quoting:
``nbd+unix:///[<export>]?socket=<domain-socket>''

Older syntax that is also recognized:
``nbd:<server-ip>:<port>[:exportname=<export>]''

Syntax for specifying a NBD device using Unix Domain Sockets
``nbd:unix:<domain-socket>[:exportname=<export>]''

Example for TCP
@example
@value{qemu_system} --drive file=nbd:192.0.2.1:30000
@end example

Example for Unix Domain Sockets
@example
@value{qemu_system} --drive file=nbd:unix:/tmp/nbd-socket
@end example

@item SSH
QEMU supports SSH (Secure Shell) access to remote disks.

Examples:
@example
@value{qemu_system} -drive file=ssh://user@@host/path/to/disk.img
@value{qemu_system} -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img
@end example

Currently authentication must be done using ssh-agent.  Other
authentication methods may be supported in future.

@item Sheepdog
Sheepdog is a distributed storage system for QEMU.
QEMU supports using either local sheepdog devices or remote networked
devices.

Syntax for specifying a sheepdog device
@example
sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag]
@end example

Example
@example
@value{qemu_system} --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine
@end example

See also @url{https://sheepdog.github.io/sheepdog/}.

@item GlusterFS
GlusterFS is a user space distributed file system.
QEMU supports the use of GlusterFS volumes for hosting VM disk images using
TCP, Unix Domain Sockets and RDMA transport protocols.

Syntax for specifying a VM disk image on GlusterFS volume is
@example

URI:
gluster[+type]://[host[:port]]/volume/path[?socket=...][,debug=N][,logfile=...]

JSON:
'json:@{"driver":"qcow2","file":@{"driver":"gluster","volume":"testvol","path":"a.img","debug":N,"logfile":"...",
@                                 "server":[@{"type":"tcp","host":"...","port":"..."@},
@                                           @{"type":"unix","socket":"..."@}]@}@}'
@end example


Example
@example
URI:
@value{qemu_system} --drive file=gluster://192.0.2.1/testvol/a.img,
@                               file.debug=9,file.logfile=/var/log/qemu-gluster.log

JSON:
@value{qemu_system} 'json:@{"driver":"qcow2",
@                          "file":@{"driver":"gluster",
@                                   "volume":"testvol","path":"a.img",
@                                   "debug":9,"logfile":"/var/log/qemu-gluster.log",
@                                   "server":[@{"type":"tcp","host":"1.2.3.4","port":24007@},
@                                             @{"type":"unix","socket":"/var/run/glusterd.socket"@}]@}@}'
@value{qemu_system} -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
@                                      file.debug=9,file.logfile=/var/log/qemu-gluster.log,
@                                      file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
@                                      file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
@end example

See also @url{http://www.gluster.org}.

@item HTTP/HTTPS/FTP/FTPS
QEMU supports read-only access to files accessed over http(s) and ftp(s).

Syntax using a single filename:
@example
<protocol>://[<username>[:<password>]@@]<host>/<path>
@end example

where:
@table @option
@item protocol
'http', 'https', 'ftp', or 'ftps'.

@item username
Optional username for authentication to the remote server.

@item password
Optional password for authentication to the remote server.

@item host
Address of the remote server.

@item path
Path on the remote server, including any query string.
@end table

The following options are also supported:
@table @option
@item url
The full URL when passing options to the driver explicitly.

@item readahead
The amount of data to read ahead with each range request to the remote server.
This value may optionally have the suffix 'T', 'G', 'M', 'K', 'k' or 'b'. If it
does not have a suffix, it will be assumed to be in bytes. The value must be a
multiple of 512 bytes. It defaults to 256k.

@item sslverify
Whether to verify the remote server's certificate when connecting over SSL. It
can have the value 'on' or 'off'. It defaults to 'on'.

@item cookie
Send this cookie (it can also be a list of cookies separated by ';') with
each outgoing request.  Only supported when using protocols such as HTTP
which support cookies, otherwise ignored.

@item timeout
Set the timeout in seconds of the CURL connection. This timeout is the time
that CURL waits for a response from the remote server to get the size of the
image to be downloaded. If not set, the default timeout of 5 seconds is used.
@end table

Note that when passing options to qemu explicitly, @option{driver} is the value
of <protocol>.

Example: boot from a remote Fedora 20 live ISO image
@example
@value{qemu_system_x86} --drive media=cdrom,file=https://archives.fedoraproject.org/pub/archive/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly

@value{qemu_system_x86} --drive media=cdrom,file.driver=http,file.url=http://archives.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly
@end example

Example: boot from a remote Fedora 20 cloud image using a local overlay for
writes, copy-on-read, and a readahead of 64k
@example
qemu-img create -f qcow2 -o backing_file='json:@{"file.driver":"http",, "file.url":"http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/20/Images/x86_64/Fedora-x86_64-20-20131211.1-sda.qcow2",, "file.readahead":"64k"@}' /tmp/Fedora-x86_64-20-20131211.1-sda.qcow2

@value{qemu_system_x86} -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-on-read=on
@end example

Example: boot from an image stored on a VMware vSphere server with a self-signed
certificate using a local overlay for writes, a readahead of 64k and a timeout
of 10 seconds.
@example
qemu-img create -f qcow2 -o backing_file='json:@{"file.driver":"https",, "file.url":"https://user:password@@vsphere.example.com/folder/test/test-flat.vmdk?dcPath=Datacenter&dsName=datastore1",, "file.sslverify":"off",, "file.readahead":"64k",, "file.timeout":10@}' /tmp/test.qcow2

@value{qemu_system_x86} -drive file=/tmp/test.qcow2
@end example

@end table

@c man end

@node pcsys_keys
@section Keys in the graphical frontends

@c man begin OPTIONS

During the graphical emulation, you can use special key combinations to change
modes. The default key mappings are shown below, but if you use @code{-alt-grab}
then the modifier is Ctrl-Alt-Shift (instead of Ctrl-Alt) and if you use
@code{-ctrl-grab} then the modifier is the right Ctrl key (instead of Ctrl-Alt):

@table @key
@item Ctrl-Alt-f
@kindex Ctrl-Alt-f
Toggle full screen

@item Ctrl-Alt-+
@kindex Ctrl-Alt-+
Enlarge the screen

@item Ctrl-Alt--
@kindex Ctrl-Alt--
Shrink the screen

@item Ctrl-Alt-u
@kindex Ctrl-Alt-u
Restore the screen's un-scaled dimensions

@item Ctrl-Alt-n
@kindex Ctrl-Alt-n
Switch to virtual console 'n'. Standard console mappings are:
@table @emph
@item 1
Target system display
@item 2
Monitor
@item 3
Serial port
@end table

@item Ctrl-Alt
@kindex Ctrl-Alt
Toggle mouse and keyboard grab.
@end table

@kindex Ctrl-Up
@kindex Ctrl-Down
@kindex Ctrl-PageUp
@kindex Ctrl-PageDown
In the virtual consoles, you can use @key{Ctrl-Up}, @key{Ctrl-Down},
@key{Ctrl-PageUp} and @key{Ctrl-PageDown} to move in the back log.

@c man end

@node mux_keys
@section Keys in the character backend multiplexer

@c man begin OPTIONS

During emulation, if you are using a character backend multiplexer
(which is the default if you are using @option{-nographic}) then
several commands are available via an escape sequence. These
key sequences all start with an escape character, which is @key{Ctrl-a}
by default, but can be changed with @option{-echr}. The list below assumes
you're using the default.

@table @key
@item Ctrl-a h
@kindex Ctrl-a h
Print this help
@item Ctrl-a x
@kindex Ctrl-a x
Exit emulator
@item Ctrl-a s
@kindex Ctrl-a s
Save disk data back to file (if -snapshot)
@item Ctrl-a t
@kindex Ctrl-a t
Toggle console timestamps
@item Ctrl-a b
@kindex Ctrl-a b
Send break (magic sysrq in Linux)
@item Ctrl-a c
@kindex Ctrl-a c
Rotate between the frontends connected to the multiplexer (usually
this switches between the monitor and the console)
@item Ctrl-a Ctrl-a
@kindex Ctrl-a Ctrl-a
Send the escape character to the frontend
@end table
@c man end

@ignore

@c man begin SEEALSO
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.
@c man end

@c man begin AUTHOR
Fabrice Bellard
@c man end

@end ignore

@node pcsys_monitor
@section QEMU Monitor
@cindex QEMU monitor

The QEMU monitor is used to give complex commands to the QEMU
emulator. You can use it to:

@itemize @minus

@item
Remove or insert removable media images
(such as CD-ROM or floppies).

@item
Freeze/unfreeze the Virtual Machine (VM) and save or restore its state
from a disk file.

@item Inspect the VM state without an external debugger.

@end itemize

@subsection Commands

The following commands are available:

@include qemu-monitor.texi

@include qemu-monitor-info.texi

@subsection Integer expressions

The monitor understands integers expressions for every integer
argument. You can use register names to get the value of specifics
CPU registers by prefixing them with @emph{$}.

@node cpu_models
@section CPU models

@include docs/qemu-cpu-models.texi

@node disk_images
@section Disk Images

QEMU supports many disk image formats, including growable disk images
(their size increase as non empty sectors are written), compressed and
encrypted disk images.

@menu
* disk_images_quickstart::    Quick start for disk image creation
* disk_images_snapshot_mode:: Snapshot mode
* vm_snapshots::              VM snapshots
* qemu_img_invocation::       qemu-img Invocation
* qemu_nbd_invocation::       qemu-nbd Invocation
* disk_images_formats::       Disk image file formats
* host_drives::               Using host drives
* disk_images_fat_images::    Virtual FAT disk images
* disk_images_nbd::           NBD access
* disk_images_sheepdog::      Sheepdog disk images
* disk_images_iscsi::         iSCSI LUNs
* disk_images_gluster::       GlusterFS disk images
* disk_images_ssh::           Secure Shell (ssh) disk images
* disk_images_nvme::          NVMe userspace driver
* disk_image_locking::        Disk image file locking
@end menu

@node disk_images_quickstart
@subsection Quick start for disk image creation

You can create a disk image with the command:
@example
qemu-img create myimage.img mysize
@end example
where @var{myimage.img} is the disk image filename and @var{mysize} is its
size in kilobytes. You can add an @code{M} suffix to give the size in
megabytes and a @code{G} suffix for gigabytes.

See @ref{qemu_img_invocation} for more information.

@node disk_images_snapshot_mode
@subsection Snapshot mode

If you use the option @option{-snapshot}, all disk images are
considered as read only. When sectors in written, they are written in
a temporary file created in @file{/tmp}. You can however force the
write back to the raw disk images by using the @code{commit} monitor
command (or @key{C-a s} in the serial console).

@node vm_snapshots
@subsection VM snapshots

VM snapshots are snapshots of the complete virtual machine including
CPU state, RAM, device state and the content of all the writable
disks. In order to use VM snapshots, you must have at least one non
removable and writable block device using the @code{qcow2} disk image
format. Normally this device is the first virtual hard drive.

Use the monitor command @code{savevm} to create a new VM snapshot or
replace an existing one. A human readable name can be assigned to each
snapshot in addition to its numerical ID.

Use @code{loadvm} to restore a VM snapshot and @code{delvm} to remove
a VM snapshot. @code{info snapshots} lists the available snapshots
with their associated information:

@example
(qemu) info snapshots
Snapshot devices: hda
Snapshot list (from hda):
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         start                   41M 2006-08-06 12:38:02   00:00:14.954
2                                 40M 2006-08-06 12:43:29   00:00:18.633
3         msys                    40M 2006-08-06 12:44:04   00:00:23.514
@end example

A VM snapshot is made of a VM state info (its size is shown in
@code{info snapshots}) and a snapshot of every writable disk image.
The VM state info is stored in the first @code{qcow2} non removable
and writable block device. The disk image snapshots are stored in
every disk image. The size of a snapshot in a disk image is difficult
to evaluate and is not shown by @code{info snapshots} because the
associated disk sectors are shared among all the snapshots to save
disk space (otherwise each snapshot would need a full copy of all the
disk images).

When using the (unrelated) @code{-snapshot} option
(@ref{disk_images_snapshot_mode}), you can always make VM snapshots,
but they are deleted as soon as you exit QEMU.

VM snapshots currently have the following known limitations:
@itemize
@item
They cannot cope with removable devices if they are removed or
inserted after a snapshot is done.
@item
A few device drivers still have incomplete snapshot support so their
state is not saved or restored properly (in particular USB).
@end itemize

@node qemu_img_invocation
@subsection @code{qemu-img} Invocation

@include qemu-img.texi

@node qemu_nbd_invocation
@subsection @code{qemu-nbd} Invocation

@include qemu-nbd.texi

@include docs/qemu-block-drivers.texi

@node pcsys_network
@section Network emulation

QEMU can simulate several network cards (e.g. PCI or ISA cards on the PC
target) and can connect them to a network backend on the host or an emulated
hub. The various host network backends can either be used to connect the NIC of
the guest to a real network (e.g. by using a TAP devices or the non-privileged
user mode network stack), or to other guest instances running in another QEMU
process (e.g. by using the socket host network backend).

@subsection Using TAP network interfaces

This is the standard way to connect QEMU to a real network. QEMU adds
a virtual network device on your host (called @code{tapN}), and you
can then configure it as if it was a real ethernet card.

@subsubsection Linux host

As an example, you can download the @file{linux-test-xxx.tar.gz}
archive and copy the script @file{qemu-ifup} in @file{/etc} and
configure properly @code{sudo} so that the command @code{ifconfig}
contained in @file{qemu-ifup} can be executed as root. You must verify
that your host kernel supports the TAP network interfaces: the
device @file{/dev/net/tun} must be present.

See @ref{sec_invocation} to have examples of command lines using the
TAP network interfaces.

@subsubsection Windows host

There is a virtual ethernet driver for Windows 2000/XP systems, called
TAP-Win32. But it is not included in standard QEMU for Windows,
so you will need to get it separately. It is part of OpenVPN package,
so download OpenVPN from : @url{https://openvpn.net/}.

@subsection Using the user mode network stack

By using the option @option{-net user} (default configuration if no
@option{-net} option is specified), QEMU uses a completely user mode
network stack (you don't need root privilege to use the virtual
network). The virtual network configuration is the following:

@example

     guest (10.0.2.15)  <------>  Firewall/DHCP server <-----> Internet
                           |          (10.0.2.2)
                           |
                           ---->  DNS server (10.0.2.3)
                           |
                           ---->  SMB server (10.0.2.4)
@end example

The QEMU VM behaves as if it was behind a firewall which blocks all
incoming connections. You can use a DHCP client to automatically
configure the network in the QEMU VM. The DHCP server assign addresses
to the hosts starting from 10.0.2.15.

In order to check that the user mode network is working, you can ping
the address 10.0.2.2 and verify that you got an address in the range
10.0.2.x from the QEMU virtual DHCP server.

Note that ICMP traffic in general does not work with user mode networking.
@code{ping}, aka. ICMP echo, to the local router (10.0.2.2) shall work,
however. If you're using QEMU on Linux >= 3.0, it can use unprivileged ICMP
ping sockets to allow @code{ping} to the Internet. The host admin has to set
the ping_group_range in order to grant access to those sockets. To allow ping
for GID 100 (usually users group):

@example
echo 100 100 > /proc/sys/net/ipv4/ping_group_range
@end example

When using the built-in TFTP server, the router is also the TFTP
server.

When using the @option{'-netdev user,hostfwd=...'} option, TCP or UDP
connections can be redirected from the host to the guest. It allows for
example to redirect X11, telnet or SSH connections.

@subsection Hubs

QEMU can simulate several hubs. A hub can be thought of as a virtual connection
between several network devices. These devices can be for example QEMU virtual
ethernet cards or virtual Host ethernet devices (TAP devices). You can connect
guest NICs or host network backends to such a hub using the @option{-netdev
hubport} or @option{-nic hubport} options. The legacy @option{-net} option
also connects the given device to the emulated hub with ID 0 (i.e. the default
hub) unless you specify a netdev with @option{-net nic,netdev=xxx} here.

@subsection Connecting emulated networks between QEMU instances

Using the @option{-netdev socket} (or @option{-nic socket} or
@option{-net socket}) option, it is possible to create emulated
networks that span several QEMU instances.
See the description of the @option{-netdev socket} option in the
@ref{sec_invocation,,Invocation chapter} to have a basic example.

@node pcsys_other_devs
@section Other Devices

@subsection Inter-VM Shared Memory device

On Linux hosts, a shared memory device is available.  The basic syntax
is:

@example
@value{qemu_system_x86} -device ivshmem-plain,memdev=@var{hostmem}
@end example

where @var{hostmem} names a host memory backend.  For a POSIX shared
memory backend, use something like

@example
-object memory-backend-file,size=1M,share,mem-path=/dev/shm/ivshmem,id=@var{hostmem}
@end example

If desired, interrupts can be sent between guest VMs accessing the same shared
memory region.  Interrupt support requires using a shared memory server and
using a chardev socket to connect to it.  The code for the shared memory server
is qemu.git/contrib/ivshmem-server.  An example syntax when using the shared
memory server is:

@example
# First start the ivshmem server once and for all
ivshmem-server -p @var{pidfile} -S @var{path} -m @var{shm-name} -l @var{shm-size} -n @var{vectors}

# Then start your qemu instances with matching arguments
@value{qemu_system_x86} -device ivshmem-doorbell,vectors=@var{vectors},chardev=@var{id}
                 -chardev socket,path=@var{path},id=@var{id}
@end example

When using the server, the guest will be assigned a VM ID (>=0) that allows guests
using the same server to communicate via interrupts.  Guests can read their
VM ID from a device register (see ivshmem-spec.txt).

@subsubsection Migration with ivshmem

With device property @option{master=on}, the guest will copy the shared
memory on migration to the destination host.  With @option{master=off},
the guest will not be able to migrate with the device attached.  In the
latter case, the device should be detached and then reattached after
migration using the PCI hotplug support.

At most one of the devices sharing the same memory can be master.  The
master must complete migration before you plug back the other devices.

@subsubsection ivshmem and hugepages

Instead of specifying the <shm size> using POSIX shm, you may specify
a memory backend that has hugepage support:

@example
@value{qemu_system_x86} -object memory-backend-file,size=1G,mem-path=/dev/hugepages/my-shmem-file,share,id=mb1
                 -device ivshmem-plain,memdev=mb1
@end example

ivshmem-server also supports hugepages mount points with the
@option{-m} memory path argument.

@node direct_linux_boot
@section Direct Linux Boot

This section explains how to launch a Linux kernel inside QEMU without
having to make a full bootable image. It is very useful for fast Linux
kernel testing.

The syntax is:
@example
@value{qemu_system} -kernel bzImage -hda rootdisk.img -append "root=/dev/hda"
@end example

Use @option{-kernel} to provide the Linux kernel image and
@option{-append} to give the kernel command line arguments. The
@option{-initrd} option can be used to provide an INITRD image.

If you do not need graphical output, you can disable it and redirect
the virtual serial port and the QEMU monitor to the console with the
@option{-nographic} option. The typical command line is:
@example
@value{qemu_system} -kernel bzImage -hda rootdisk.img \
                 -append "root=/dev/hda console=ttyS0" -nographic
@end example

Use @key{Ctrl-a c} to switch between the serial console and the
monitor (@pxref{pcsys_keys}).

@node pcsys_usb
@section USB emulation

QEMU can emulate a PCI UHCI, OHCI, EHCI or XHCI USB controller. You can
plug virtual USB devices or real host USB devices (only works with certain
host operating systems). QEMU will automatically create and connect virtual
USB hubs as necessary to connect multiple USB devices.

@menu
* usb_devices::
* host_usb_devices::
@end menu
@node usb_devices
@subsection Connecting USB devices

USB devices can be connected with the @option{-device usb-...} command line
option or the @code{device_add} monitor command. Available devices are:

@table @code
@item usb-mouse
Virtual Mouse.  This will override the PS/2 mouse emulation when activated.
@item usb-tablet
Pointer device that uses absolute coordinates (like a touchscreen).
This means QEMU is able to report the mouse position without having
to grab the mouse.  Also overrides the PS/2 mouse emulation when activated.
@item usb-storage,drive=@var{drive_id}
Mass storage device backed by @var{drive_id} (@pxref{disk_images})
@item usb-uas
USB attached SCSI device, see
@url{https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt,usb-storage.txt}
for details
@item usb-bot
Bulk-only transport storage device, see
@url{https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt,usb-storage.txt}
for details here, too
@item usb-mtp,rootdir=@var{dir}
Media transfer protocol device, using @var{dir} as root of the file tree
that is presented to the guest.
@item usb-host,hostbus=@var{bus},hostaddr=@var{addr}
Pass through the host device identified by @var{bus} and @var{addr}
@item usb-host,vendorid=@var{vendor},productid=@var{product}
Pass through the host device identified by @var{vendor} and @var{product} ID
@item usb-wacom-tablet
Virtual Wacom PenPartner tablet.  This device is similar to the @code{tablet}
above but it can be used with the tslib library because in addition to touch
coordinates it reports touch pressure.
@item usb-kbd
Standard USB keyboard.  Will override the PS/2 keyboard (if present).
@item usb-serial,chardev=@var{id}
Serial converter. This emulates an FTDI FT232BM chip connected to host character
device @var{id}.
@item usb-braille,chardev=@var{id}
Braille device.  This will use BrlAPI to display the braille output on a real
or fake device referenced by @var{id}.
@item usb-net[,netdev=@var{id}]
Network adapter that supports CDC ethernet and RNDIS protocols.  @var{id}
specifies a netdev defined with @code{-netdev @dots{},id=@var{id}}.
For instance, user-mode networking can be used with
@example
@value{qemu_system} [...] -netdev user,id=net0 -device usb-net,netdev=net0
@end example
@item usb-ccid
Smartcard reader device
@item usb-audio
USB audio device
@item usb-bt-dongle
Bluetooth dongle for the transport layer of HCI. It is connected to HCI
scatternet 0 by default (corresponds to @code{-bt hci,vlan=0}).
Note that the syntax for the @code{-device usb-bt-dongle} option is not as
useful yet as it was with the legacy @code{-usbdevice} option. So to
configure an USB bluetooth device, you might need to use
"@code{-usbdevice bt}[:@var{hci-type}]" instead. This configures a
bluetooth dongle whose type is specified in the same format as with
the @option{-bt hci} option, @pxref{bt-hcis,,allowed HCI types}.  If
no type is given, the HCI logic corresponds to @code{-bt hci,vlan=0}.
This USB device implements the USB Transport Layer of HCI.  Example
usage:
@example
@command{@value{qemu_system}} [...@var{OPTIONS}...] @option{-usbdevice} bt:hci,vlan=3 @option{-bt} device:keyboard,vlan=3
@end example
@end table

@node host_usb_devices
@subsection Using host USB devices on a Linux host

WARNING: this is an experimental feature. QEMU will slow down when
using it. USB devices requiring real time streaming (i.e. USB Video
Cameras) are not supported yet.

@enumerate
@item If you use an early Linux 2.4 kernel, verify that no Linux driver
is actually using the USB device. A simple way to do that is simply to
disable the corresponding kernel module by renaming it from @file{mydriver.o}
to @file{mydriver.o.disabled}.

@item Verify that @file{/proc/bus/usb} is working (most Linux distributions should enable it by default). You should see something like that:
@example
ls /proc/bus/usb
001  devices  drivers
@end example

@item Since only root can access to the USB devices directly, you can either launch QEMU as root or change the permissions of the USB devices you want to use. For testing, the following suffices:
@example
chown -R myuid /proc/bus/usb
@end example

@item Launch QEMU and do in the monitor:
@example
info usbhost
  Device 1.2, speed 480 Mb/s
    Class 00: USB device 1234:5678, USB DISK
@end example
You should see the list of the devices you can use (Never try to use
hubs, it won't work).

@item Add the device in QEMU by using:
@example
device_add usb-host,vendorid=0x1234,productid=0x5678
@end example

Normally the guest OS should report that a new USB device is plugged.
You can use the option @option{-device usb-host,...} to do the same.

@item Now you can try to use the host USB device in QEMU.

@end enumerate

When relaunching QEMU, you may have to unplug and plug again the USB
device to make it work again (this is a bug).

@node vnc_security
@section VNC security

The VNC server capability provides access to the graphical console
of the guest VM across the network. This has a number of security
considerations depending on the deployment scenarios.

@menu
* vnc_sec_none::
* vnc_sec_password::
* vnc_sec_certificate::
* vnc_sec_certificate_verify::
* vnc_sec_certificate_pw::
* vnc_sec_sasl::
* vnc_sec_certificate_sasl::
* vnc_setup_sasl::
@end menu
@node vnc_sec_none
@subsection Without passwords

The simplest VNC server setup does not include any form of authentication.
For this setup it is recommended to restrict it to listen on a UNIX domain
socket only. For example

@example
@value{qemu_system} [...OPTIONS...] -vnc unix:/home/joebloggs/.qemu-myvm-vnc
@end example

This ensures that only users on local box with read/write access to that
path can access the VNC server. To securely access the VNC server from a
remote machine, a combination of netcat+ssh can be used to provide a secure
tunnel.

@node vnc_sec_password
@subsection With passwords

The VNC protocol has limited support for password based authentication. Since
the protocol limits passwords to 8 characters it should not be considered
to provide high security. The password can be fairly easily brute-forced by
a client making repeat connections. For this reason, a VNC server using password
authentication should be restricted to only listen on the loopback interface
or UNIX domain sockets. Password authentication is not supported when operating
in FIPS 140-2 compliance mode as it requires the use of the DES cipher. Password
authentication is requested with the @code{password} option, and then once QEMU
is running the password is set with the monitor. Until the monitor is used to
set the password all clients will be rejected.

@example
@value{qemu_system} [...OPTIONS...] -vnc :1,password -monitor stdio
(qemu) change vnc password
Password: ********
(qemu)
@end example

@node vnc_sec_certificate
@subsection With x509 certificates

The QEMU VNC server also implements the VeNCrypt extension allowing use of
TLS for encryption of the session, and x509 certificates for authentication.
The use of x509 certificates is strongly recommended, because TLS on its
own is susceptible to man-in-the-middle attacks. Basic x509 certificate
support provides a secure session, but no authentication. This allows any
client to connect, and provides an encrypted session.

@example
@value{qemu_system} [...OPTIONS...] \
  -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=no \
  -vnc :1,tls-creds=tls0 -monitor stdio
@end example

In the above example @code{/etc/pki/qemu} should contain at least three files,
@code{ca-cert.pem}, @code{server-cert.pem} and @code{server-key.pem}. Unprivileged
users will want to use a private directory, for example @code{$HOME/.pki/qemu}.
NB the @code{server-key.pem} file should be protected with file mode 0600 to
only be readable by the user owning it.

@node vnc_sec_certificate_verify
@subsection With x509 certificates and client verification

Certificates can also provide a means to authenticate the client connecting.
The server will request that the client provide a certificate, which it will
then validate against the CA certificate. This is a good choice if deploying
in an environment with a private internal certificate authority. It uses the
same syntax as previously, but with @code{verify-peer} set to @code{yes}
instead.

@example
@value{qemu_system} [...OPTIONS...] \
  -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=yes \
  -vnc :1,tls-creds=tls0 -monitor stdio
@end example


@node vnc_sec_certificate_pw
@subsection With x509 certificates, client verification and passwords

Finally, the previous method can be combined with VNC password authentication
to provide two layers of authentication for clients.

@example
@value{qemu_system} [...OPTIONS...] \
  -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=yes \
  -vnc :1,tls-creds=tls0,password -monitor stdio
(qemu) change vnc password
Password: ********
(qemu)
@end example


@node vnc_sec_sasl
@subsection With SASL authentication

The SASL authentication method is a VNC extension, that provides an
easily extendable, pluggable authentication method. This allows for
integration with a wide range of authentication mechanisms, such as
PAM, GSSAPI/Kerberos, LDAP, SQL databases, one-time keys and more.
The strength of the authentication depends on the exact mechanism
configured. If the chosen mechanism also provides a SSF layer, then
it will encrypt the datastream as well.

Refer to the later docs on how to choose the exact SASL mechanism
used for authentication, but assuming use of one supporting SSF,
then QEMU can be launched with:

@example
@value{qemu_system} [...OPTIONS...] -vnc :1,sasl -monitor stdio
@end example

@node vnc_sec_certificate_sasl
@subsection With x509 certificates and SASL authentication

If the desired SASL authentication mechanism does not supported
SSF layers, then it is strongly advised to run it in combination
with TLS and x509 certificates. This provides securely encrypted
data stream, avoiding risk of compromising of the security
credentials. This can be enabled, by combining the 'sasl' option
with the aforementioned TLS + x509 options:

@example
@value{qemu_system} [...OPTIONS...] \
  -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=yes \
  -vnc :1,tls-creds=tls0,sasl -monitor stdio
@end example

@node vnc_setup_sasl

@subsection Configuring SASL mechanisms

The following documentation assumes use of the Cyrus SASL implementation on a
Linux host, but the principles should apply to any other SASL implementation
or host. When SASL is enabled, the mechanism configuration will be loaded from
system default SASL service config /etc/sasl2/qemu.conf. If running QEMU as an
unprivileged user, an environment variable SASL_CONF_PATH can be used to make
it search alternate locations for the service config file.

If the TLS option is enabled for VNC, then it will provide session encryption,
otherwise the SASL mechanism will have to provide encryption. In the latter
case the list of possible plugins that can be used is drastically reduced. In
fact only the GSSAPI SASL mechanism provides an acceptable level of security
by modern standards. Previous versions of QEMU referred to the DIGEST-MD5
mechanism, however, it has multiple serious flaws described in detail in
RFC 6331 and thus should never be used any more. The SCRAM-SHA-1 mechanism
provides a simple username/password auth facility similar to DIGEST-MD5, but
does not support session encryption, so can only be used in combination with
TLS.

When not using TLS the recommended configuration is

@example
mech_list: gssapi
keytab: /etc/qemu/krb5.tab
@end example

This says to use the 'GSSAPI' mechanism with the Kerberos v5 protocol, with
the server principal stored in /etc/qemu/krb5.tab. For this to work the
administrator of your KDC must generate a Kerberos principal for the server,
with a name of 'qemu/somehost.example.com@@EXAMPLE.COM' replacing
'somehost.example.com' with the fully qualified host name of the machine
running QEMU, and 'EXAMPLE.COM' with the Kerberos Realm.

When using TLS, if username+password authentication is desired, then a
reasonable configuration is

@example
mech_list: scram-sha-1
sasldb_path: /etc/qemu/passwd.db
@end example

The @code{saslpasswd2} program can be used to populate the @code{passwd.db}
file with accounts.

Other SASL configurations will be left as an exercise for the reader. Note that
all mechanisms, except GSSAPI, should be combined with use of TLS to ensure a
secure data channel.


@node network_tls
@section TLS setup for network services

Almost all network services in QEMU have the ability to use TLS for
session data encryption, along with x509 certificates for simple
client authentication. What follows is a description of how to
generate certificates suitable for usage with QEMU, and applies to
the VNC server, character devices with the TCP backend, NBD server
and client, and migration server and client.

At a high level, QEMU requires certificates and private keys to be
provided in PEM format. Aside from the core fields, the certificates
should include various extension data sets, including v3 basic
constraints data, key purpose, key usage and subject alt name.

The GnuTLS package includes a command called @code{certtool} which can
be used to easily generate certificates and keys in the required format
with expected data present. Alternatively a certificate management
service may be used.

At a minimum it is necessary to setup a certificate authority, and
issue certificates to each server. If using x509 certificates for
authentication, then each client will also need to be issued a
certificate.

Assuming that the QEMU network services will only ever be exposed to
clients on a private intranet, there is no need to use a commercial
certificate authority to create certificates. A self-signed CA is
sufficient, and in fact likely to be more secure since it removes
the ability of malicious 3rd parties to trick the CA into mis-issuing
certs for impersonating your services. The only likely exception
where a commercial CA might be desirable is if enabling the VNC
websockets server and exposing it directly to remote browser clients.
In such a case it might be useful to use a commercial CA to avoid
needing to install custom CA certs in the web browsers.

The recommendation is for the server to keep its certificates in either
@code{/etc/pki/qemu} or for unprivileged users in @code{$HOME/.pki/qemu}.

@menu
* tls_generate_ca::
* tls_generate_server::
* tls_generate_client::
* tls_creds_setup::
* tls_psk::
@end menu
@node tls_generate_ca
@subsection Setup the Certificate Authority

This step only needs to be performed once per organization / organizational
unit. First the CA needs a private key. This key must be kept VERY secret
and secure. If this key is compromised the entire trust chain of the certificates
issued with it is lost.

@example
# certtool --generate-privkey > ca-key.pem
@end example

To generate a self-signed certificate requires one core piece of information,
the name of the organization. A template file @code{ca.info} should be
populated with the desired data to avoid having to deal with interactive
prompts from certtool:
@example
# cat > ca.info <<EOF
cn = Name of your organization
ca
cert_signing_key
EOF
# certtool --generate-self-signed \
           --load-privkey ca-key.pem
           --template ca.info \
           --outfile ca-cert.pem
@end example

The @code{ca} keyword in the template sets the v3 basic constraints extension
to indicate this certificate is for a CA, while @code{cert_signing_key} sets
the key usage extension to indicate this will be used for signing other keys.
The generated @code{ca-cert.pem} file should be copied to all servers and
clients wishing to utilize TLS support in the VNC server. The @code{ca-key.pem}
must not be disclosed/copied anywhere except the host responsible for issuing
certificates.

@node tls_generate_server
@subsection Issuing server certificates

Each server (or host) needs to be issued with a key and certificate. When connecting
the certificate is sent to the client which validates it against the CA certificate.
The core pieces of information for a server certificate are the hostnames and/or IP
addresses that will be used by clients when connecting. The hostname / IP address
that the client specifies when connecting will be validated against the hostname(s)
and IP address(es) recorded in the server certificate, and if no match is found
the client will close the connection.

Thus it is recommended that the server certificate include both the fully qualified
and unqualified hostnames. If the server will have permanently assigned IP address(es),
and clients are likely to use them when connecting, they may also be included in the
certificate. Both IPv4 and IPv6 addresses are supported. Historically certificates
only included 1 hostname in the @code{CN} field, however, usage of this field for
validation is now deprecated. Instead modern TLS clients will validate against the
Subject Alt Name extension data, which allows for multiple entries. In the future
usage of the @code{CN} field may be discontinued entirely, so providing SAN
extension data is strongly recommended.

On the host holding the CA, create template files containing the information
for each server, and use it to issue server certificates.

@example
# cat > server-hostNNN.info <<EOF
organization = Name  of your organization
cn = hostNNN.foo.example.com
dns_name = hostNNN
dns_name = hostNNN.foo.example.com
ip_address = 10.0.1.87
ip_address = 192.8.0.92
ip_address = 2620:0:cafe::87
ip_address = 2001:24::92
tls_www_server
encryption_key
signing_key
EOF
# certtool --generate-privkey > server-hostNNN-key.pem
# certtool --generate-certificate \
           --load-ca-certificate ca-cert.pem \
           --load-ca-privkey ca-key.pem \
           --load-privkey server-hostNNN-key.pem \
           --template server-hostNNN.info \
           --outfile server-hostNNN-cert.pem
@end example

The @code{dns_name} and @code{ip_address} fields in the template are setting
the subject alt name extension data. The @code{tls_www_server} keyword is the
key purpose extension to indicate this certificate is intended for usage in
a web server. Although QEMU network services are not in fact HTTP servers
(except for VNC websockets), setting this key purpose is still recommended.
The @code{encryption_key} and @code{signing_key} keyword is the key usage
extension to indicate this certificate is intended for usage in the data
session.

The @code{server-hostNNN-key.pem} and @code{server-hostNNN-cert.pem} files
should now be securely copied to the server for which they were generated,
and renamed to @code{server-key.pem} and @code{server-cert.pem} when added
to the @code{/etc/pki/qemu} directory on the target host. The @code{server-key.pem}
file is security sensitive and should be kept protected with file mode 0600
to prevent disclosure.

@node tls_generate_client
@subsection Issuing client certificates

The QEMU x509 TLS credential setup defaults to enabling client verification
using certificates, providing a simple authentication mechanism. If this
default is used, each client also needs to be issued a certificate. The client
certificate contains enough metadata to uniquely identify the client with the
scope of the certificate authority. The client certificate would typically
include fields for organization, state, city, building, etc.

Once again on the host holding the CA, create template files containing the
information for each client, and use it to issue client certificates.


@example
# cat > client-hostNNN.info <<EOF
country = GB
state = London
locality = City Of London
organization = Name of your organization
cn = hostNNN.foo.example.com
tls_www_client
encryption_key
signing_key
EOF
# certtool --generate-privkey > client-hostNNN-key.pem
# certtool --generate-certificate \
           --load-ca-certificate ca-cert.pem \
           --load-ca-privkey ca-key.pem \
           --load-privkey client-hostNNN-key.pem \
           --template client-hostNNN.info \
           --outfile client-hostNNN-cert.pem
@end example

The subject alt name extension data is not required for clients, so the
the @code{dns_name} and @code{ip_address} fields are not included.
The @code{tls_www_client} keyword is the key purpose extension to indicate
this certificate is intended for usage in a web client. Although QEMU
network clients are not in fact HTTP clients, setting this key purpose is
still recommended. The @code{encryption_key} and @code{signing_key} keyword
is the key usage extension to indicate this certificate is intended for
usage in the data session.

The @code{client-hostNNN-key.pem} and @code{client-hostNNN-cert.pem} files
should now be securely copied to the client for which they were generated,
and renamed to @code{client-key.pem} and @code{client-cert.pem} when added
to the @code{/etc/pki/qemu} directory on the target host. The @code{client-key.pem}
file is security sensitive and should be kept protected with file mode 0600
to prevent disclosure.

If a single host is going to be using TLS in both a client and server
role, it is possible to create a single certificate to cover both roles.
This would be quite common for the migration and NBD services, where a
QEMU process will be started by accepting a TLS protected incoming migration,
and later itself be migrated out to another host. To generate a single
certificate, simply include the template data from both the client and server
instructions in one.

@example
# cat > both-hostNNN.info <<EOF
country = GB
state = London
locality = City Of London
organization = Name of your organization
cn = hostNNN.foo.example.com
dns_name = hostNNN
dns_name = hostNNN.foo.example.com
ip_address = 10.0.1.87
ip_address = 192.8.0.92
ip_address = 2620:0:cafe::87
ip_address = 2001:24::92
tls_www_server
tls_www_client
encryption_key
signing_key
EOF
# certtool --generate-privkey > both-hostNNN-key.pem
# certtool --generate-certificate \
           --load-ca-certificate ca-cert.pem \
           --load-ca-privkey ca-key.pem \
           --load-privkey both-hostNNN-key.pem \
           --template both-hostNNN.info \
           --outfile both-hostNNN-cert.pem
@end example

When copying the PEM files to the target host, save them twice,
once as @code{server-cert.pem} and @code{server-key.pem}, and
again as @code{client-cert.pem} and @code{client-key.pem}.

@node tls_creds_setup
@subsection TLS x509 credential configuration

QEMU has a standard mechanism for loading x509 credentials that will be
used for network services and clients. It requires specifying the
@code{tls-creds-x509} class name to the @code{--object} command line
argument for the system emulators.  Each set of credentials loaded should
be given a unique string identifier via the @code{id} parameter. A single
set of TLS credentials can be used for multiple network backends, so VNC,
migration, NBD, character devices can all share the same credentials. Note,
however, that credentials for use in a client endpoint must be loaded
separately from those used in a server endpoint.

When specifying the object, the @code{dir} parameters specifies which
directory contains the credential files. This directory is expected to
contain files with the names mentioned previously, @code{ca-cert.pem},
@code{server-key.pem}, @code{server-cert.pem}, @code{client-key.pem}
and @code{client-cert.pem} as appropriate. It is also possible to
include a set of pre-generated Diffie-Hellman (DH) parameters in a file
@code{dh-params.pem}, which can be created using the
@code{certtool --generate-dh-params} command. If omitted, QEMU will
dynamically generate DH parameters when loading the credentials.

The @code{endpoint} parameter indicates whether the credentials will
be used for a network client or server, and determines which PEM
files are loaded.

The @code{verify} parameter determines whether x509 certificate
validation should be performed. This defaults to enabled, meaning
clients will always validate the server hostname against the
certificate subject alt name fields and/or CN field. It also
means that servers will request that clients provide a certificate
and validate them. Verification should never be turned off for
client endpoints, however, it may be turned off for server endpoints
if an alternative mechanism is used to authenticate clients. For
example, the VNC server can use SASL to authenticate clients
instead.

To load server credentials with client certificate validation
enabled

@example
@value{qemu_system} -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server
@end example

while to load client credentials use

@example
@value{qemu_system} -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=client
@end example

Network services which support TLS will all have a @code{tls-creds}
parameter which expects the ID of the TLS credentials object. For
example with VNC:

@example
@value{qemu_system} -vnc 0.0.0.0:0,tls-creds=tls0
@end example

@node tls_psk
@subsection TLS Pre-Shared Keys (PSK)

Instead of using certificates, you may also use TLS Pre-Shared Keys
(TLS-PSK).  This can be simpler to set up than certificates but is
less scalable.

Use the GnuTLS @code{psktool} program to generate a @code{keys.psk}
file containing one or more usernames and random keys:

@example
mkdir -m 0700 /tmp/keys
psktool -u rich -p /tmp/keys/keys.psk
@end example

TLS-enabled servers such as qemu-nbd can use this directory like so:

@example
qemu-nbd \
  -t -x / \
  --object tls-creds-psk,id=tls0,endpoint=server,dir=/tmp/keys \
  --tls-creds tls0 \
  image.qcow2
@end example

When connecting from a qemu-based client you must specify the
directory containing @code{keys.psk} and an optional @var{username}
(defaults to ``qemu''):

@example
qemu-img info \
  --object tls-creds-psk,id=tls0,dir=/tmp/keys,username=rich,endpoint=client \
  --image-opts \
  file.driver=nbd,file.host=localhost,file.port=10809,file.tls-creds=tls0,file.export=/
@end example

@node gdb_usage
@section GDB usage

QEMU has a primitive support to work with gdb, so that you can do
'Ctrl-C' while the virtual machine is running and inspect its state.

In order to use gdb, launch QEMU with the '-s' option. It will wait for a
gdb connection:
@example
@value{qemu_system} -s -kernel bzImage -hda rootdisk.img -append "root=/dev/hda"
Connected to host network interface: tun0
Waiting gdb connection on port 1234
@end example

Then launch gdb on the 'vmlinux' executable:
@example
> gdb vmlinux
@end example

In gdb, connect to QEMU:
@example
(gdb) target remote localhost:1234
@end example

Then you can use gdb normally. For example, type 'c' to launch the kernel:
@example
(gdb) c
@end example

Here are some useful tips in order to use gdb on system code:

@enumerate
@item
Use @code{info reg} to display all the CPU registers.
@item
Use @code{x/10i $eip} to display the code at the PC position.
@item
Use @code{set architecture i8086} to dump 16 bit code. Then use
@code{x/10i $cs*16+$eip} to dump the code at the PC position.
@end enumerate

Advanced debugging options:

The default single stepping behavior is step with the IRQs and timer service routines off.  It is set this way because when gdb executes a single step it expects to advance beyond the current instruction.  With the IRQs and timer service routines on, a single step might jump into the one of the interrupt or exception vectors instead of executing the current instruction. This means you may hit the same breakpoint a number of times before executing the instruction gdb wants to have executed.  Because there are rare circumstances where you want to single step into an interrupt vector the behavior can be controlled from GDB.  There are three commands you can query and set the single step behavior:
@table @code
@item maintenance packet qqemu.sstepbits

This will display the MASK bits used to control the single stepping IE:
@example
(gdb) maintenance packet qqemu.sstepbits
sending: "qqemu.sstepbits"
received: "ENABLE=1,NOIRQ=2,NOTIMER=4"
@end example
@item maintenance packet qqemu.sstep

This will display the current value of the mask used when single stepping IE:
@example
(gdb) maintenance packet qqemu.sstep
sending: "qqemu.sstep"
received: "0x7"
@end example
@item maintenance packet Qqemu.sstep=HEX_VALUE

This will change the single step mask, so if wanted to enable IRQs on the single step, but not timers, you would use:
@example
(gdb) maintenance packet Qqemu.sstep=0x5
sending: "qemu.sstep=0x5"
received: "OK"
@end example
@end table

@node pcsys_os_specific
@section Target OS specific information

@subsection Linux

To have access to SVGA graphic modes under X11, use the @code{vesa} or
the @code{cirrus} X11 driver. For optimal performances, use 16 bit
color depth in the guest and the host OS.

When using a 2.6 guest Linux kernel, you should add the option
@code{clock=pit} on the kernel command line because the 2.6 Linux
kernels make very strict real time clock checks by default that QEMU
cannot simulate exactly.

When using a 2.6 guest Linux kernel, verify that the 4G/4G patch is
not activated because QEMU is slower with this patch. The QEMU
Accelerator Module is also much slower in this case. Earlier Fedora
Core 3 Linux kernel (< 2.6.9-1.724_FC3) were known to incorporate this
patch by default. Newer kernels don't have it.

@subsection Windows

If you have a slow host, using Windows 95 is better as it gives the
best speed. Windows 2000 is also a good choice.

@subsubsection SVGA graphic modes support

QEMU emulates a Cirrus Logic GD5446 Video
card. All Windows versions starting from Windows 95 should recognize
and use this graphic card. For optimal performances, use 16 bit color
depth in the guest and the host OS.

If you are using Windows XP as guest OS and if you want to use high
resolution modes which the Cirrus Logic BIOS does not support (i.e. >=
1280x1024x16), then you should use the VESA VBE virtual graphic card
(option @option{-std-vga}).

@subsubsection CPU usage reduction

Windows 9x does not correctly use the CPU HLT
instruction. The result is that it takes host CPU cycles even when
idle. You can install the utility from
@url{https://web.archive.org/web/20060212132151/http://www.user.cityline.ru/~maxamn/amnhltm.zip}
to solve this problem. Note that no such tool is needed for NT, 2000 or XP.

@subsubsection Windows 2000 disk full problem

Windows 2000 has a bug which gives a disk full problem during its
installation. When installing it, use the @option{-win2k-hack} QEMU
option to enable a specific workaround. After Windows 2000 is
installed, you no longer need this option (this option slows down the
IDE transfers).

@subsubsection Windows 2000 shutdown

Windows 2000 cannot automatically shutdown in QEMU although Windows 98
can. It comes from the fact that Windows 2000 does not automatically
use the APM driver provided by the BIOS.

In order to correct that, do the following (thanks to Struan
Bartlett): go to the Control Panel => Add/Remove Hardware & Next =>
Add/Troubleshoot a device => Add a new device & Next => No, select the
hardware from a list & Next => NT Apm/Legacy Support & Next => Next
(again) a few times. Now the driver is installed and Windows 2000 now
correctly instructs QEMU to shutdown at the appropriate moment.

@subsubsection Share a directory between Unix and Windows

See @ref{sec_invocation} about the help of the option
@option{'-netdev user,smb=...'}.

@subsubsection Windows XP security problem

Some releases of Windows XP install correctly but give a security
error when booting:
@example
A problem is preventing Windows from accurately checking the
license for this computer. Error code: 0x800703e6.
@end example

The workaround is to install a service pack for XP after a boot in safe
mode. Then reboot, and the problem should go away. Since there is no
network while in safe mode, its recommended to download the full
installation of SP1 or SP2 and transfer that via an ISO or using the
vvfat block device ("-hdb fat:directory_which_holds_the_SP").

@subsection MS-DOS and FreeDOS

@subsubsection CPU usage reduction

DOS does not correctly use the CPU HLT instruction. The result is that
it takes host CPU cycles even when idle. You can install the utility from
@url{https://web.archive.org/web/20051222085335/http://www.vmware.com/software/dosidle210.zip}
to solve this problem.

@node QEMU System emulator for non PC targets
@chapter QEMU System emulator for non PC targets

QEMU is a generic emulator and it emulates many non PC
machines. Most of the options are similar to the PC emulator. The
differences are mentioned in the following sections.

@menu
* PowerPC System emulator::
* Sparc32 System emulator::
* Sparc64 System emulator::
* MIPS System emulator::
* ARM System emulator::
* ColdFire System emulator::
* Cris System emulator::
* Microblaze System emulator::
* SH4 System emulator::
* Xtensa System emulator::
@end menu

@node PowerPC System emulator
@section PowerPC System emulator
@cindex system emulation (PowerPC)

Use the executable @file{qemu-system-ppc} to simulate a complete PREP
or PowerMac PowerPC system.

QEMU emulates the following PowerMac peripherals:

@itemize @minus
@item
UniNorth or Grackle PCI Bridge
@item
PCI VGA compatible card with VESA Bochs Extensions
@item
2 PMAC IDE interfaces with hard disk and CD-ROM support
@item
NE2000 PCI adapters
@item
Non Volatile RAM
@item
VIA-CUDA with ADB keyboard and mouse.
@end itemize

QEMU emulates the following PREP peripherals:

@itemize @minus
@item
PCI Bridge
@item
PCI VGA compatible card with VESA Bochs Extensions
@item
2 IDE interfaces with hard disk and CD-ROM support
@item
Floppy disk
@item
NE2000 network adapters
@item
Serial port
@item
PREP Non Volatile RAM
@item
PC compatible keyboard and mouse.
@end itemize

QEMU uses the Open Hack'Ware Open Firmware Compatible BIOS available at
@url{http://perso.magic.fr/l_indien/OpenHackWare/index.htm}.

Since version 0.9.1, QEMU uses OpenBIOS @url{https://www.openbios.org/}
for the g3beige and mac99 PowerMac machines. OpenBIOS is a free (GPL
v2) portable firmware implementation. The goal is to implement a 100%
IEEE 1275-1994 (referred to as Open Firmware) compliant firmware.

@c man begin OPTIONS

The following options are specific to the PowerPC emulation:

@table @option

@item -g @var{W}x@var{H}[x@var{DEPTH}]

Set the initial VGA graphic mode. The default is 800x600x32.

@item -prom-env @var{string}

Set OpenBIOS variables in NVRAM, for example:

@example
qemu-system-ppc -prom-env 'auto-boot?=false' \
 -prom-env 'boot-device=hd:2,\yaboot' \
 -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
@end example

These variables are not used by Open Hack'Ware.

@end table

@c man end


More information is available at
@url{http://perso.magic.fr/l_indien/qemu-ppc/}.

@node Sparc32 System emulator
@section Sparc32 System emulator
@cindex system emulation (Sparc32)

Use the executable @file{qemu-system-sparc} to simulate the following
Sun4m architecture machines:
@itemize @minus
@item
SPARCstation 4
@item
SPARCstation 5
@item
SPARCstation 10
@item
SPARCstation 20
@item
SPARCserver 600MP
@item
SPARCstation LX
@item
SPARCstation Voyager
@item
SPARCclassic
@item
SPARCbook
@end itemize

The emulation is somewhat complete. SMP up to 16 CPUs is supported,
but Linux limits the number of usable CPUs to 4.

QEMU emulates the following sun4m peripherals:

@itemize @minus
@item
IOMMU
@item
TCX or cgthree Frame buffer
@item
Lance (Am7990) Ethernet
@item
Non Volatile RAM M48T02/M48T08
@item
Slave I/O: timers, interrupt controllers, Zilog serial ports, keyboard
and power/reset logic
@item
ESP SCSI controller with hard disk and CD-ROM support
@item
Floppy drive (not on SS-600MP)
@item
CS4231 sound device (only on SS-5, not working yet)
@end itemize

The number of peripherals is fixed in the architecture.  Maximum
memory size depends on the machine type, for SS-5 it is 256MB and for
others 2047MB.

Since version 0.8.2, QEMU uses OpenBIOS
@url{https://www.openbios.org/}. OpenBIOS is a free (GPL v2) portable
firmware implementation. The goal is to implement a 100% IEEE
1275-1994 (referred to as Open Firmware) compliant firmware.

A sample Linux 2.6 series kernel and ram disk image are available on
the QEMU web site. There are still issues with NetBSD and OpenBSD, but
most kernel versions work. Please note that currently older Solaris kernels
don't work probably due to interface issues between OpenBIOS and
Solaris.

@c man begin OPTIONS

The following options are specific to the Sparc32 emulation:

@table @option

@item -g @var{W}x@var{H}x[x@var{DEPTH}]

Set the initial graphics mode. For TCX, the default is 1024x768x8 with the
option of 1024x768x24. For cgthree, the default is 1024x768x8 with the option
of 1152x900x8 for people who wish to use OBP.

@item -prom-env @var{string}

Set OpenBIOS variables in NVRAM, for example:

@example
qemu-system-sparc -prom-env 'auto-boot?=false' \
 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
@end example

@item -M [SS-4|SS-5|SS-10|SS-20|SS-600MP|LX|Voyager|SPARCClassic] [|SPARCbook]

Set the emulated machine type. Default is SS-5.

@end table

@c man end

@node Sparc64 System emulator
@section Sparc64 System emulator
@cindex system emulation (Sparc64)

Use the executable @file{qemu-system-sparc64} to simulate a Sun4u
(UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or generic
Niagara (T1) machine. The Sun4u emulator is mostly complete, being
able to run Linux, NetBSD and OpenBSD in headless (-nographic) mode. The
Sun4v emulator is still a work in progress.

The Niagara T1 emulator makes use of firmware and OS binaries supplied in the S10image/ directory
of the OpenSPARC T1 project @url{http://download.oracle.com/technetwork/systems/opensparc/OpenSPARCT1_Arch.1.5.tar.bz2}
and is able to boot the disk.s10hw2 Solaris image.
@example
qemu-system-sparc64 -M niagara -L /path-to/S10image/ \
                    -nographic -m 256 \
                    -drive if=pflash,readonly=on,file=/S10image/disk.s10hw2
@end example


QEMU emulates the following peripherals:

@itemize @minus
@item
UltraSparc IIi APB PCI Bridge
@item
PCI VGA compatible card with VESA Bochs Extensions
@item
PS/2 mouse and keyboard
@item
Non Volatile RAM M48T59
@item
PC-compatible serial ports
@item
2 PCI IDE interfaces with hard disk and CD-ROM support
@item
Floppy disk
@end itemize

@c man begin OPTIONS

The following options are specific to the Sparc64 emulation:

@table @option

@item -prom-env @var{string}

Set OpenBIOS variables in NVRAM, for example:

@example
qemu-system-sparc64 -prom-env 'auto-boot?=false'
@end example

@item -M [sun4u|sun4v|niagara]

Set the emulated machine type. The default is sun4u.

@end table

@c man end

@node MIPS System emulator
@section MIPS System emulator
@cindex system emulation (MIPS)

@menu
* nanoMIPS System emulator ::
@end menu

Four executables cover simulation of 32 and 64-bit MIPS systems in
both endian options, @file{qemu-system-mips}, @file{qemu-system-mipsel}
@file{qemu-system-mips64} and @file{qemu-system-mips64el}.
Five different machine types are emulated:

@itemize @minus
@item
A generic ISA PC-like machine "mips"
@item
The MIPS Malta prototype board "malta"
@item
An ACER Pica "pica61". This machine needs the 64-bit emulator.
@item
MIPS emulator pseudo board "mipssim"
@item
A MIPS Magnum R4000 machine "magnum". This machine needs the 64-bit emulator.
@end itemize

The generic emulation is supported by Debian 'Etch' and is able to
install Debian into a virtual disk image. The following devices are
emulated:

@itemize @minus
@item
A range of MIPS CPUs, default is the 24Kf
@item
PC style serial port
@item
PC style IDE disk
@item
NE2000 network card
@end itemize

The Malta emulation supports the following devices:

@itemize @minus
@item
Core board with MIPS 24Kf CPU and Galileo system controller
@item
PIIX4 PCI/USB/SMbus controller
@item
The Multi-I/O chip's serial device
@item
PCI network cards (PCnet32 and others)
@item
Malta FPGA serial device
@item
Cirrus (default) or any other PCI VGA graphics card
@end itemize

The Boston board emulation supports the following devices:

@itemize @minus
@item
Xilinx FPGA, which includes a PCIe root port and an UART
@item
Intel EG20T PCH connects the I/O peripherals, but only the SATA bus is emulated
@end itemize

The ACER Pica emulation supports:

@itemize @minus
@item
MIPS R4000 CPU
@item
PC-style IRQ and DMA controllers
@item
PC Keyboard
@item
IDE controller
@end itemize

The MIPS Magnum R4000 emulation supports:

@itemize @minus
@item
MIPS R4000 CPU
@item
PC-style IRQ controller
@item
PC Keyboard
@item
SCSI controller
@item
G364 framebuffer
@end itemize

The Fulong 2E emulation supports:

@itemize @minus
@item
Loongson 2E CPU
@item
Bonito64 system controller as North Bridge
@item
VT82C686 chipset as South Bridge
@item
RTL8139D as a network card chipset
@end itemize

The mipssim pseudo board emulation provides an environment similar
to what the proprietary MIPS emulator uses for running Linux.
It supports:

@itemize @minus
@item
A range of MIPS CPUs, default is the 24Kf
@item
PC style serial port
@item
MIPSnet network emulation
@end itemize

@node nanoMIPS System emulator
@subsection nanoMIPS System emulator
@cindex system emulation (nanoMIPS)

Executable @file{qemu-system-mipsel} also covers simulation of
32-bit nanoMIPS system in little endian mode:

@itemize @minus
@item
nanoMIPS I7200 CPU
@end itemize

Example of @file{qemu-system-mipsel} usage for nanoMIPS is shown below:

Download @code{<disk_image_file>} from @url{https://mipsdistros.mips.com/LinuxDistro/nanomips/buildroot/index.html}.

Download @code{<kernel_image_file>} from @url{https://mipsdistros.mips.com/LinuxDistro/nanomips/kernels/v4.15.18-432-gb2eb9a8b07a1-20180627102142/index.html}.

Start system emulation of Malta board with nanoMIPS I7200 CPU:
@example
qemu-system-mipsel -cpu I7200 -kernel @code{<kernel_image_file>} \
    -M malta -serial stdio -m @code{<memory_size>} -hda @code{<disk_image_file>} \
    -append "mem=256m@@0x0 rw console=ttyS0 vga=cirrus vesa=0x111 root=/dev/sda"
@end example


@node ARM System emulator
@section ARM System emulator
@cindex system emulation (ARM)

Use the executable @file{qemu-system-arm} to simulate a ARM
machine. The ARM Integrator/CP board is emulated with the following
devices:

@itemize @minus
@item
ARM926E, ARM1026E, ARM946E, ARM1136 or Cortex-A8 CPU
@item
Two PL011 UARTs
@item
SMC 91c111 Ethernet adapter
@item
PL110 LCD controller
@item
PL050 KMI with PS/2 keyboard and mouse.
@item
PL181 MultiMedia Card Interface with SD card.
@end itemize

The ARM Versatile baseboard is emulated with the following devices:

@itemize @minus
@item
ARM926E, ARM1136 or Cortex-A8 CPU
@item
PL190 Vectored Interrupt Controller
@item
Four PL011 UARTs
@item
SMC 91c111 Ethernet adapter
@item
PL110 LCD controller
@item
PL050 KMI with PS/2 keyboard and mouse.
@item
PCI host bridge.  Note the emulated PCI bridge only provides access to
PCI memory space.  It does not provide access to PCI IO space.
This means some devices (eg. ne2k_pci NIC) are not usable, and others
(eg. rtl8139 NIC) are only usable when the guest drivers use the memory
mapped control registers.
@item
PCI OHCI USB controller.
@item
LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices.
@item
PL181 MultiMedia Card Interface with SD card.
@end itemize

Several variants of the ARM RealView baseboard are emulated,
including the EB, PB-A8 and PBX-A9.  Due to interactions with the
bootloader, only certain Linux kernel configurations work out
of the box on these boards.

Kernels for the PB-A8 board should have CONFIG_REALVIEW_HIGH_PHYS_OFFSET
enabled in the kernel, and expect 512M RAM.  Kernels for The PBX-A9 board
should have CONFIG_SPARSEMEM enabled, CONFIG_REALVIEW_HIGH_PHYS_OFFSET
disabled and expect 1024M RAM.

The following devices are emulated:

@itemize @minus
@item
ARM926E, ARM1136, ARM11MPCore, Cortex-A8 or Cortex-A9 MPCore CPU
@item
ARM AMBA Generic/Distributed Interrupt Controller
@item
Four PL011 UARTs
@item
SMC 91c111 or SMSC LAN9118 Ethernet adapter
@item
PL110 LCD controller
@item
PL050 KMI with PS/2 keyboard and mouse
@item
PCI host bridge
@item
PCI OHCI USB controller
@item
LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices
@item
PL181 MultiMedia Card Interface with SD card.
@end itemize

The XScale-based clamshell PDA models ("Spitz", "Akita", "Borzoi"
and "Terrier") emulation includes the following peripherals:

@itemize @minus
@item
Intel PXA270 System-on-chip (ARM V5TE core)
@item
NAND Flash memory
@item
IBM/Hitachi DSCM microdrive in a PXA PCMCIA slot - not in "Akita"
@item
On-chip OHCI USB controller
@item
On-chip LCD controller
@item
On-chip Real Time Clock
@item
TI ADS7846 touchscreen controller on SSP bus
@item
Maxim MAX1111 analog-digital converter on I@math{^2}C bus
@item
GPIO-connected keyboard controller and LEDs
@item
Secure Digital card connected to PXA MMC/SD host
@item
Three on-chip UARTs
@item
WM8750 audio CODEC on I@math{^2}C and I@math{^2}S busses
@end itemize

The Palm Tungsten|E PDA (codename "Cheetah") emulation includes the
following elements:

@itemize @minus
@item
Texas Instruments OMAP310 System-on-chip (ARM 925T core)
@item
ROM and RAM memories (ROM firmware image can be loaded with -option-rom)
@item
On-chip LCD controller
@item
On-chip Real Time Clock
@item
TI TSC2102i touchscreen controller / analog-digital converter / Audio
CODEC, connected through MicroWire and I@math{^2}S busses
@item
GPIO-connected matrix keypad
@item
Secure Digital card connected to OMAP MMC/SD host
@item
Three on-chip UARTs
@end itemize

Nokia N800 and N810 internet tablets (known also as RX-34 and RX-44 / 48)
emulation supports the following elements:

@itemize @minus
@item
Texas Instruments OMAP2420 System-on-chip (ARM 1136 core)
@item
RAM and non-volatile OneNAND Flash memories
@item
Display connected to EPSON remote framebuffer chip and OMAP on-chip
display controller and a LS041y3 MIPI DBI-C controller
@item
TI TSC2301 (in N800) and TI TSC2005 (in N810) touchscreen controllers
driven through SPI bus
@item
National Semiconductor LM8323-controlled qwerty keyboard driven
through I@math{^2}C bus
@item
Secure Digital card connected to OMAP MMC/SD host
@item
Three OMAP on-chip UARTs and on-chip STI debugging console
@item
A Bluetooth(R) transceiver and HCI connected to an UART
@item
Mentor Graphics "Inventra" dual-role USB controller embedded in a TI
TUSB6010 chip - only USB host mode is supported
@item
TI TMP105 temperature sensor driven through I@math{^2}C bus
@item
TI TWL92230C power management companion with an RTC on I@math{^2}C bus
@item
Nokia RETU and TAHVO multi-purpose chips with an RTC, connected
through CBUS
@end itemize

The Luminary Micro Stellaris LM3S811EVB emulation includes the following
devices:

@itemize @minus
@item
Cortex-M3 CPU core.
@item
64k Flash and 8k SRAM.
@item
Timers, UARTs, ADC and I@math{^2}C interface.
@item
OSRAM Pictiva 96x16 OLED with SSD0303 controller on I@math{^2}C bus.
@end itemize

The Luminary Micro Stellaris LM3S6965EVB emulation includes the following
devices:

@itemize @minus
@item
Cortex-M3 CPU core.
@item
256k Flash and 64k SRAM.
@item
Timers, UARTs, ADC, I@math{^2}C and SSI interfaces.
@item
OSRAM Pictiva 128x64 OLED with SSD0323 controller connected via SSI.
@end itemize

The Freecom MusicPal internet radio emulation includes the following
elements:

@itemize @minus
@item
Marvell MV88W8618 ARM core.
@item
32 MB RAM, 256 KB SRAM, 8 MB flash.
@item
Up to 2 16550 UARTs
@item
MV88W8xx8 Ethernet controller
@item
MV88W8618 audio controller, WM8750 CODEC and mixer
@item
128×64 display with brightness control
@item
2 buttons, 2 navigation wheels with button function
@end itemize

The Siemens SX1 models v1 and v2 (default) basic emulation.
The emulation includes the following elements:

@itemize @minus
@item
Texas Instruments OMAP310 System-on-chip (ARM 925T core)
@item
ROM and RAM memories (ROM firmware image can be loaded with -pflash)
V1
1 Flash of 16MB and 1 Flash of 8MB
V2
1 Flash of 32MB
@item
On-chip LCD controller
@item
On-chip Real Time Clock
@item
Secure Digital card connected to OMAP MMC/SD host
@item
Three on-chip UARTs
@end itemize

A Linux 2.6 test image is available on the QEMU web site. More
information is available in the QEMU mailing-list archive.

@c man begin OPTIONS

The following options are specific to the ARM emulation:

@table @option

@item -semihosting
Enable semihosting syscall emulation.

On ARM this implements the "Angel" interface.

Note that this allows guest direct access to the host filesystem,
so should only be used with trusted guest OS.

@end table

@c man end

@node ColdFire System emulator
@section ColdFire System emulator
@cindex system emulation (ColdFire)
@cindex system emulation (M68K)

Use the executable @file{qemu-system-m68k} to simulate a ColdFire machine.
The emulator is able to boot a uClinux kernel.

The M5208EVB emulation includes the following devices:

@itemize @minus
@item
MCF5208 ColdFire V2 Microprocessor (ISA A+ with EMAC).
@item
Three Two on-chip UARTs.
@item
Fast Ethernet Controller (FEC)
@end itemize

The AN5206 emulation includes the following devices:

@itemize @minus
@item
MCF5206 ColdFire V2 Microprocessor.
@item
Two on-chip UARTs.
@end itemize

@c man begin OPTIONS

The following options are specific to the ColdFire emulation:

@table @option

@item -semihosting
Enable semihosting syscall emulation.

On M68K this implements the "ColdFire GDB" interface used by libgloss.

Note that this allows guest direct access to the host filesystem,
so should only be used with trusted guest OS.

@end table

@c man end

@node Cris System emulator
@section Cris System emulator
@cindex system emulation (Cris)

TODO

@node Microblaze System emulator
@section Microblaze System emulator
@cindex system emulation (Microblaze)

TODO

@node SH4 System emulator
@section SH4 System emulator
@cindex system emulation (SH4)

TODO

@node Xtensa System emulator
@section Xtensa System emulator
@cindex system emulation (Xtensa)

Two executables cover simulation of both Xtensa endian options,
@file{qemu-system-xtensa} and @file{qemu-system-xtensaeb}.
Two different machine types are emulated:

@itemize @minus
@item
Xtensa emulator pseudo board "sim"
@item
Avnet LX60/LX110/LX200 board
@end itemize

The sim pseudo board emulation provides an environment similar
to one provided by the proprietary Tensilica ISS.
It supports:

@itemize @minus
@item
A range of Xtensa CPUs, default is the DC232B
@item
Console and filesystem access via semihosting calls
@end itemize

The Avnet LX60/LX110/LX200 emulation supports:

@itemize @minus
@item
A range of Xtensa CPUs, default is the DC232B
@item
16550 UART
@item
OpenCores 10/100 Mbps Ethernet MAC
@end itemize

@c man begin OPTIONS

The following options are specific to the Xtensa emulation:

@table @option

@item -semihosting
Enable semihosting syscall emulation.

Xtensa semihosting provides basic file IO calls, such as open/read/write/seek/select.
Tensilica baremetal libc for ISS and linux platform "sim" use this interface.

Note that this allows guest direct access to the host filesystem,
so should only be used with trusted guest OS.

@end table

@c man end

@node QEMU User space emulator
@chapter QEMU User space emulator

@menu
* Supported Operating Systems ::
* Features::
* Linux User space emulator::
* BSD User space emulator ::
@end menu

@node Supported Operating Systems
@section Supported Operating Systems

The following OS are supported in user space emulation:

@itemize @minus
@item
Linux (referred as qemu-linux-user)
@item
BSD (referred as qemu-bsd-user)
@end itemize

@node Features
@section Features

QEMU user space emulation has the following notable features:

@table @strong
@item System call translation:
QEMU includes a generic system call translator.  This means that
the parameters of the system calls can be converted to fix
endianness and 32/64-bit mismatches between hosts and targets.
IOCTLs can be converted too.

@item POSIX signal handling:
QEMU can redirect to the running program all signals coming from
the host (such as @code{SIGALRM}), as well as synthesize signals from
virtual CPU exceptions (for example @code{SIGFPE} when the program
executes a division by zero).

QEMU relies on the host kernel to emulate most signal system
calls, for example to emulate the signal mask.  On Linux, QEMU
supports both normal and real-time signals.

@item Threading:
On Linux, QEMU can emulate the @code{clone} syscall and create a real
host thread (with a separate virtual CPU) for each emulated thread.
Note that not all targets currently emulate atomic operations correctly.
x86 and ARM use a global lock in order to preserve their semantics.
@end table

QEMU was conceived so that ultimately it can emulate itself. Although
it is not very useful, it is an important test to show the power of the
emulator.

@node Linux User space emulator
@section Linux User space emulator

@menu
* Quick Start::
* Wine launch::
* Command line options::
* Other binaries::
@end menu

@node Quick Start
@subsection Quick Start

In order to launch a Linux process, QEMU needs the process executable
itself and all the target (x86) dynamic libraries used by it.

@itemize

@item On x86, you can just try to launch any process by using the native
libraries:

@example
qemu-i386 -L / /bin/ls
@end example

@code{-L /} tells that the x86 dynamic linker must be searched with a
@file{/} prefix.

@item Since QEMU is also a linux process, you can launch QEMU with
QEMU (NOTE: you can only do that if you compiled QEMU from the sources):

@example
qemu-i386 -L / qemu-i386 -L / /bin/ls
@end example

@item On non x86 CPUs, you need first to download at least an x86 glibc
(@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that
@code{LD_LIBRARY_PATH} is not set:

@example
unset LD_LIBRARY_PATH
@end example

Then you can launch the precompiled @file{ls} x86 executable:

@example
qemu-i386 tests/i386/ls
@end example
You can look at @file{scripts/qemu-binfmt-conf.sh} so that
QEMU is automatically launched by the Linux kernel when you try to
launch x86 executables. It requires the @code{binfmt_misc} module in the
Linux kernel.

@item The x86 version of QEMU is also included. You can try weird things such as:
@example
qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 \
          /usr/local/qemu-i386/bin/ls-i386
@end example

@end itemize

@node Wine launch
@subsection Wine launch

@itemize

@item Ensure that you have a working QEMU with the x86 glibc
distribution (see previous section). In order to verify it, you must be
able to do:

@example
qemu-i386 /usr/local/qemu-i386/bin/ls-i386
@end example

@item Download the binary x86 Wine install
(@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page).

@item Configure Wine on your account. Look at the provided script
@file{/usr/local/qemu-i386/@/bin/wine-conf.sh}. Your previous
@code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}.

@item Then you can try the example @file{putty.exe}:

@example
qemu-i386 /usr/local/qemu-i386/wine/bin/wine \
          /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe
@end example

@end itemize

@node Command line options
@subsection Command line options

@example
@command{qemu-i386} [@option{-h]} [@option{-d]} [@option{-L} @var{path}] [@option{-s} @var{size}] [@option{-cpu} @var{model}] [@option{-g} @var{port}] [@option{-B} @var{offset}] [@option{-R} @var{size}] @var{program} [@var{arguments}...]
@end example

@table @option
@item -h
Print the help
@item -L path
Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
@item -s size
Set the x86 stack size in bytes (default=524288)
@item -cpu model
Select CPU model (-cpu help for list and additional feature selection)
@item -E @var{var}=@var{value}
Set environment @var{var} to @var{value}.
@item -U @var{var}
Remove @var{var} from the environment.
@item -B offset
Offset guest address by the specified number of bytes.  This is useful when
the address region required by guest applications is reserved on the host.
This option is currently only supported on some hosts.
@item -R size
Pre-allocate a guest virtual address space of the given size (in bytes).
"G", "M", and "k" suffixes may be used when specifying the size.
@end table

Debug options:

@table @option
@item -d item1,...
Activate logging of the specified items (use '-d help' for a list of log items)
@item -p pagesize
Act as if the host page size was 'pagesize' bytes
@item -g port
Wait gdb connection to port
@item -singlestep
Run the emulation in single step mode.
@end table

Environment variables:

@table @env
@item QEMU_STRACE
Print system calls and arguments similar to the 'strace' program
(NOTE: the actual 'strace' program will not work because the user
space emulator hasn't implemented ptrace).  At the moment this is
incomplete.  All system calls that don't have a specific argument
format are printed with information for six arguments.  Many
flag-style arguments don't have decoders and will show up as numbers.
@end table

@node Other binaries
@subsection Other binaries

@cindex user mode (Alpha)
@command{qemu-alpha} TODO.

@cindex user mode (ARM)
@command{qemu-armeb} TODO.

@cindex user mode (ARM)
@command{qemu-arm} is also capable of running ARM "Angel" semihosted ELF
binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB
configurations), and arm-uclinux bFLT format binaries.

@cindex user mode (ColdFire)
@cindex user mode (M68K)
@command{qemu-m68k} is capable of running semihosted binaries using the BDM
(m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and
coldfire uClinux bFLT format binaries.

The binary format is detected automatically.

@cindex user mode (Cris)
@command{qemu-cris} TODO.

@cindex user mode (i386)
@command{qemu-i386} TODO.
@command{qemu-x86_64} TODO.

@cindex user mode (Microblaze)
@command{qemu-microblaze} TODO.

@cindex user mode (MIPS)
@command{qemu-mips} executes 32-bit big endian MIPS binaries (MIPS O32 ABI).

@command{qemu-mipsel} executes 32-bit little endian MIPS binaries (MIPS O32 ABI).

@command{qemu-mips64} executes 64-bit big endian MIPS binaries (MIPS N64 ABI).

@command{qemu-mips64el} executes 64-bit little endian MIPS binaries (MIPS N64 ABI).

@command{qemu-mipsn32} executes 32-bit big endian MIPS binaries (MIPS N32 ABI).

@command{qemu-mipsn32el} executes 32-bit little endian MIPS binaries (MIPS N32 ABI).

@cindex user mode (NiosII)
@command{qemu-nios2} TODO.

@cindex user mode (PowerPC)
@command{qemu-ppc64abi32} TODO.
@command{qemu-ppc64} TODO.
@command{qemu-ppc} TODO.

@cindex user mode (SH4)
@command{qemu-sh4eb} TODO.
@command{qemu-sh4} TODO.

@cindex user mode (SPARC)
@command{qemu-sparc} can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).

@command{qemu-sparc32plus} can execute Sparc32 and SPARC32PLUS binaries
(Sparc64 CPU, 32 bit ABI).

@command{qemu-sparc64} can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and
SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).

@node BSD User space emulator
@section BSD User space emulator

@menu
* BSD Status::
* BSD Quick Start::
* BSD Command line options::
@end menu

@node BSD Status
@subsection BSD Status

@itemize @minus
@item
target Sparc64 on Sparc64: Some trivial programs work.
@end itemize

@node BSD Quick Start
@subsection Quick Start

In order to launch a BSD process, QEMU needs the process executable
itself and all the target dynamic libraries used by it.

@itemize

@item On Sparc64, you can just try to launch any process by using the native
libraries:

@example
qemu-sparc64 /bin/ls
@end example

@end itemize

@node BSD Command line options
@subsection Command line options

@example
@command{qemu-sparc64} [@option{-h]} [@option{-d]} [@option{-L} @var{path}] [@option{-s} @var{size}] [@option{-bsd} @var{type}] @var{program} [@var{arguments}...]
@end example

@table @option
@item -h
Print the help
@item -L path
Set the library root path (default=/)
@item -s size
Set the stack size in bytes (default=524288)
@item -ignore-environment
Start with an empty environment. Without this option,
the initial environment is a copy of the caller's environment.
@item -E @var{var}=@var{value}
Set environment @var{var} to @var{value}.
@item -U @var{var}
Remove @var{var} from the environment.
@item -bsd type
Set the type of the emulated BSD Operating system. Valid values are
FreeBSD, NetBSD and OpenBSD (default).
@end table

Debug options:

@table @option
@item -d item1,...
Activate logging of the specified items (use '-d help' for a list of log items)
@item -p pagesize
Act as if the host page size was 'pagesize' bytes
@item -singlestep
Run the emulation in single step mode.
@end table

@node System requirements
@chapter System requirements

@section KVM kernel module

On x86_64 hosts, the default set of CPU features enabled by the KVM accelerator
require the host to be running Linux v4.5 or newer.

The OpteronG[345] CPU models require KVM support for RDTSCP, which was
added with Linux 4.5 which is supported by the major distros. And even
if RHEL7 has kernel 3.10, KVM there has the required functionality there
to make it close to a 4.5 or newer kernel.

@include docs/security.texi

@include qemu-tech.texi

@include qemu-deprecated.texi

@node Supported build platforms
@appendix Supported build platforms

QEMU aims to support building and executing on multiple host OS platforms.
This appendix outlines which platforms are the major build targets. These
platforms are used as the basis for deciding upon the minimum required
versions of 3rd party software QEMU depends on. The supported platforms
are the targets for automated testing performed by the project when patches
are submitted for review, and tested before and after merge.

If a platform is not listed here, it does not imply that QEMU won't work.
If an unlisted platform has comparable software versions to a listed platform,
there is every expectation that it will work. Bug reports are welcome for
problems encountered on unlisted platforms unless they are clearly older
vintage than what is described here.

Note that when considering software versions shipped in distros as support
targets, QEMU considers only the version number, and assumes the features in
that distro match the upstream release with the same version. In other words,
if a distro backports extra features to the software in their distro, QEMU
upstream code will not add explicit support for those backports, unless the
feature is auto-detectable in a manner that works for the upstream releases
too.

The Repology site @url{https://repology.org} is a useful resource to identify
currently shipped versions of software in various operating systems, though
it does not cover all distros listed below.

@section Linux OS

For distributions with frequent, short-lifetime releases, the project will
aim to support all versions that are not end of life by their respective
vendors. For the purposes of identifying supported software versions, the
project will look at Fedora, Ubuntu, and openSUSE distros. Other short-
lifetime distros will be assumed to ship similar software versions.

For distributions with long-lifetime releases, the project will aim to support
the most recent major version at all times. Support for the previous major
version will be dropped 2 years after the new major version is released. For
the purposes of identifying supported software versions, the project will look
at RHEL, Debian, Ubuntu LTS, and SLES distros. Other long-lifetime distros will
be assumed to ship similar software versions.

@section Windows

The project supports building with current versions of the MinGW toolchain,
hosted on Linux.

@section macOS

The project supports building with the two most recent versions of macOS, with
the current homebrew package set available.

@section FreeBSD

The project aims to support the all the versions which are not end of life.

@section NetBSD

The project aims to support the most recent major version at all times. Support
for the previous major version will be dropped 2 years after the new major
version is released.

@section OpenBSD

The project aims to support the all the versions which are not end of life.

@node License
@appendix License

QEMU is a trademark of Fabrice Bellard.

QEMU is released under the
@url{https://www.gnu.org/licenses/gpl-2.0.txt,GNU General Public License},
version 2. Parts of QEMU have specific licenses, see file
@url{https://git.qemu.org/?p=qemu.git;a=blob_plain;f=LICENSE,LICENSE}.

@node Index
@appendix Index
@menu
* Concept Index::
* Function Index::
* Keystroke Index::
* Program Index::
* Data Type Index::
* Variable Index::
@end menu

@node Concept Index
@section Concept Index
This is the main index. Should we combine all keywords in one index? TODO
@printindex cp

@node Function Index
@section Function Index
This index could be used for command line options and monitor functions.
@printindex fn

@node Keystroke Index
@section Keystroke Index

This is a list of all keystrokes which have a special function
in system emulation.

@printindex ky

@node Program Index
@section Program Index
@printindex pg

@node Data Type Index
@section Data Type Index

This index could be used for qdev device names and options.

@printindex tp

@node Variable Index
@section Variable Index
@printindex vr

@bye