aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/kernel-parameters.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt198
1 files changed, 87 insertions, 111 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 7ce5ea949d1a..fb80e9ffea68 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -34,7 +34,6 @@ parameter is applicable:
34 APIC APIC support is enabled. 34 APIC APIC support is enabled.
35 APM Advanced Power Management support is enabled. 35 APM Advanced Power Management support is enabled.
36 AX25 Appropriate AX.25 support is enabled. 36 AX25 Appropriate AX.25 support is enabled.
37 CD Appropriate CD support is enabled.
38 DRM Direct Rendering Management support is enabled. 37 DRM Direct Rendering Management support is enabled.
39 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled 38 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
40 EFI EFI Partitioning (GPT) is enabled 39 EFI EFI Partitioning (GPT) is enabled
@@ -170,7 +169,10 @@ and is between 256 and 4096 characters. It is defined in the file
170 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS 169 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
171 Format: To spoof as Windows 98: ="Microsoft Windows" 170 Format: To spoof as Windows 98: ="Microsoft Windows"
172 171
173 acpi_osi= [HW,ACPI] empty param disables _OSI 172 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
173 acpi_osi="string1" # add string1 -- only one string
174 acpi_osi="!string2" # remove built-in string2
175 acpi_osi= # disable all strings
174 176
175 acpi_serialize [HW,ACPI] force serialization of AML methods 177 acpi_serialize [HW,ACPI] force serialization of AML methods
176 178
@@ -235,16 +237,9 @@ and is between 256 and 4096 characters. It is defined in the file
235 Disable PIN 1 of APIC timer 237 Disable PIN 1 of APIC timer
236 Can be useful to work around chipset bugs. 238 Can be useful to work around chipset bugs.
237 239
238 ad1816= [HW,OSS]
239 Format: <io>,<irq>,<dma>,<dma2>
240 See also Documentation/sound/oss/AD1816.
241
242 ad1848= [HW,OSS] 240 ad1848= [HW,OSS]
243 Format: <io>,<irq>,<dma>,<dma2>,<type> 241 Format: <io>,<irq>,<dma>,<dma2>,<type>
244 242
245 adlib= [HW,OSS]
246 Format: <io>
247
248 advansys= [HW,SCSI] 243 advansys= [HW,SCSI]
249 See header of drivers/scsi/advansys.c. 244 See header of drivers/scsi/advansys.c.
250 245
@@ -323,9 +318,6 @@ and is between 256 and 4096 characters. It is defined in the file
323 318
324 autotest [IA64] 319 autotest [IA64]
325 320
326 aztcd= [HW,CD] Aztech CD268 CDROM driver
327 Format: <io>,0x79 (?)
328
329 baycom_epp= [HW,AX25] 321 baycom_epp= [HW,AX25]
330 Format: <io>,<mode> 322 Format: <io>,<mode>
331 323
@@ -368,10 +360,6 @@ and is between 256 and 4096 characters. It is defined in the file
368 possible to determine what the correct size should be. 360 possible to determine what the correct size should be.
369 This option provides an override for these situations. 361 This option provides an override for these situations.
370 362
371 cdu31a= [HW,CD]
372 Format: <io>,<irq>[,PAS]
373 See header of drivers/cdrom/cdu31a.c.
374
375 chandev= [HW,NET] Generic channel device initialisation 363 chandev= [HW,NET] Generic channel device initialisation
376 364
377 checkreqprot [SELINUX] Set initial checkreqprot flag value. 365 checkreqprot [SELINUX] Set initial checkreqprot flag value.
@@ -425,9 +413,6 @@ and is between 256 and 4096 characters. It is defined in the file
425 hpet= [IA-32,HPET] option to disable HPET and use PIT. 413 hpet= [IA-32,HPET] option to disable HPET and use PIT.
426 Format: disable 414 Format: disable
427 415
428 cm206= [HW,CD]
429 Format: { auto | [<io>,][<irq>] }
430
431 com20020= [HW,NET] ARCnet - COM20020 chipset 416 com20020= [HW,NET] ARCnet - COM20020 chipset
432 Format: 417 Format:
433 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 418 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
@@ -459,13 +444,20 @@ and is between 256 and 4096 characters. It is defined in the file
459 Documentation/networking/netconsole.txt for an 444 Documentation/networking/netconsole.txt for an
460 alternative. 445 alternative.
461 446
462 uart,io,<addr>[,options] 447 uart[8250],io,<addr>[,options]
463 uart,mmio,<addr>[,options] 448 uart[8250],mmio,<addr>[,options]
464 Start an early, polled-mode console on the 8250/16550 449 Start an early, polled-mode console on the 8250/16550
465 UART at the specified I/O port or MMIO address, 450 UART at the specified I/O port or MMIO address,
466 switching to the matching ttyS device later. The 451 switching to the matching ttyS device later. The
467 options are the same as for ttyS, above. 452 options are the same as for ttyS, above.
468 453
454 earlycon= [KNL] Output early console device and options.
455 uart[8250],io,<addr>[,options]
456 uart[8250],mmio,<addr>[,options]
457 Start an early, polled-mode console on the 8250/16550
458 UART at the specified I/O port or MMIO address.
459 The options are the same as for ttyS, above.
460
469 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 461 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
470 Format: 462 Format:
471 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 463 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
@@ -657,9 +649,6 @@ and is between 256 and 4096 characters. It is defined in the file
657 gpt [EFI] Forces disk with valid GPT signature but 649 gpt [EFI] Forces disk with valid GPT signature but
658 invalid Protective MBR to be treated as GPT. 650 invalid Protective MBR to be treated as GPT.
659 651
660 gscd= [HW,CD]
661 Format: <io>
662
663 gvp11= [HW,SCSI] 652 gvp11= [HW,SCSI]
664 653
665 hashdist= [KNL,NUMA] Large hashes allocated during boot 654 hashdist= [KNL,NUMA] Large hashes allocated during boot
@@ -823,14 +812,37 @@ and is between 256 and 4096 characters. It is defined in the file
823 tasks in the system -- can cause problems and 812 tasks in the system -- can cause problems and
824 suboptimal load balancer performance. 813 suboptimal load balancer performance.
825 814
826 isp16= [HW,CD]
827 Format: <io>,<irq>,<dma>,<setup>
828
829 iucv= [HW,NET] 815 iucv= [HW,NET]
830 816
831 js= [HW,JOY] Analog joystick 817 js= [HW,JOY] Analog joystick
832 See Documentation/input/joystick.txt. 818 See Documentation/input/joystick.txt.
833 819
820 kernelcore=nn[KMG] [KNL,IA-32,IA-64,PPC,X86-64] This parameter
821 specifies the amount of memory usable by the kernel
822 for non-movable allocations. The requested amount is
823 spread evenly throughout all nodes in the system. The
824 remaining memory in each node is used for Movable
825 pages. In the event, a node is too small to have both
826 kernelcore and Movable pages, kernelcore pages will
827 take priority and other nodes will have a larger number
828 of kernelcore pages. The Movable zone is used for the
829 allocation of pages that may be reclaimed or moved
830 by the page migration subsystem. This means that
831 HugeTLB pages may not be allocated from this zone.
832 Note that allocations like PTEs-from-HighMem still
833 use the HighMem zone if it exists, and the Normal
834 zone if it does not.
835
836 movablecore=nn[KMG] [KNL,IA-32,IA-64,PPC,X86-64] This parameter
837 is similar to kernelcore except it specifies the
838 amount of memory used for migratable allocations.
839 If both kernelcore and movablecore is specified,
840 then kernelcore will be at *least* the specified
841 value but may be more. If movablecore on its own
842 is specified, the administrator must be careful
843 that the amount of memory usable for all allocations
844 is not too small.
845
834 keepinitrd [HW,ARM] 846 keepinitrd [HW,ARM]
835 847
836 kstack=N [IA-32,X86-64] Print N words from the kernel stack 848 kstack=N [IA-32,X86-64] Print N words from the kernel stack
@@ -964,11 +976,6 @@ and is between 256 and 4096 characters. It is defined in the file
964 976
965 mcatest= [IA-64] 977 mcatest= [IA-64]
966 978
967 mcd= [HW,CD]
968 Format: <port>,<irq>,<mitsumi_bug_93_wait>
969
970 mcdx= [HW,CD]
971
972 mce [IA-32] Machine Check Exception 979 mce [IA-32] Machine Check Exception
973 980
974 md= [HW] RAID subsystems devices and level 981 md= [HW] RAID subsystems devices and level
@@ -1011,49 +1018,6 @@ and is between 256 and 4096 characters. It is defined in the file
1011 1018
1012 mga= [HW,DRM] 1019 mga= [HW,DRM]
1013 1020
1014 migration_cost=
1015 [KNL,SMP] debug: override scheduler migration costs
1016 Format: <level-1-usecs>,<level-2-usecs>,...
1017 This debugging option can be used to override the
1018 default scheduler migration cost matrix. The numbers
1019 are indexed by 'CPU domain distance'.
1020 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
1021 box will set up an intra-core migration cost of
1022 1 msec, an inter-core migration cost of 2 msecs,
1023 and an inter-node migration cost of 3 msecs.
1024
1025 WARNING: using the wrong values here can break
1026 scheduler performance, so it's only for scheduler
1027 development purposes, not production environments.
1028
1029 migration_debug=
1030 [KNL,SMP] migration cost auto-detect verbosity
1031 Format=<0|1|2>
1032 If a system's migration matrix reported at bootup
1033 seems erroneous then this option can be used to
1034 increase verbosity of the detection process.
1035 We default to 0 (no extra messages), 1 will print
1036 some more information, and 2 will be really
1037 verbose (probably only useful if you also have a
1038 serial console attached to the system).
1039
1040 migration_factor=
1041 [KNL,SMP] multiply/divide migration costs by a factor
1042 Format=<percent>
1043 This debug option can be used to proportionally
1044 increase or decrease the auto-detected migration
1045 costs for all entries of the migration matrix.
1046 E.g. migration_factor=150 will increase migration
1047 costs by 50%. (and thus the scheduler will be less
1048 eager migrating cache-hot tasks)
1049 migration_factor=80 will decrease migration costs
1050 by 20%. (thus the scheduler will be more eager to
1051 migrate tasks)
1052
1053 WARNING: using the wrong values here can break
1054 scheduler performance, so it's only for scheduler
1055 development purposes, not production environments.
1056
1057 mousedev.tap_time= 1021 mousedev.tap_time=
1058 [MOUSE] Maximum time between finger touching and 1022 [MOUSE] Maximum time between finger touching and
1059 leaving touchpad surface for touch to be considered 1023 leaving touchpad surface for touch to be considered
@@ -1190,6 +1154,8 @@ and is between 256 and 4096 characters. It is defined in the file
1190 1154
1191 nointroute [IA-64] 1155 nointroute [IA-64]
1192 1156
1157 nojitter [IA64] Disables jitter checking for ITC timers.
1158
1193 nolapic [IA-32,APIC] Do not enable or use the local APIC. 1159 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1194 1160
1195 nolapic_timer [IA-32,APIC] Do not use the local APIC timer. 1161 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
@@ -1221,6 +1187,8 @@ and is between 256 and 4096 characters. It is defined in the file
1221 1187
1222 nosmp [SMP] Tells an SMP kernel to act as a UP kernel. 1188 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1223 1189
1190 nosoftlockup [KNL] Disable the soft-lockup detector.
1191
1224 nosync [HW,M68K] Disables sync negotiation for all devices. 1192 nosync [HW,M68K] Disables sync negotiation for all devices.
1225 1193
1226 notsc [BUGS=IA-32] Disable Time Stamp Counter 1194 notsc [BUGS=IA-32] Disable Time Stamp Counter
@@ -1229,20 +1197,19 @@ and is between 256 and 4096 characters. It is defined in the file
1229 1197
1230 nowb [ARM] 1198 nowb [ARM]
1231 1199
1200 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1201 one of ['zone', 'node', 'default'] can be specified
1202 This can be set from sysctl after boot.
1203 See Documentation/sysctl/vm.txt for details.
1204
1232 nr_uarts= [SERIAL] maximum number of UARTs to be registered. 1205 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1233 1206
1234 opl3= [HW,OSS] 1207 opl3= [HW,OSS]
1235 Format: <io> 1208 Format: <io>
1236 1209
1237 opl3sa2= [HW,OSS] Format:
1238 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1239
1240 oprofile.timer= [HW] 1210 oprofile.timer= [HW]
1241 Use timer interrupt instead of performance counters 1211 Use timer interrupt instead of performance counters
1242 1212
1243 optcd= [HW,CD]
1244 Format: <io>
1245
1246 osst= [HW,SCSI] SCSI Tape Driver 1213 osst= [HW,SCSI] SCSI Tape Driver
1247 Format: <buffer_size>,<write_threshold> 1214 Format: <buffer_size>,<write_threshold>
1248 See also Documentation/scsi/st.txt. 1215 See also Documentation/scsi/st.txt.
@@ -1421,6 +1388,15 @@ and is between 256 and 4096 characters. It is defined in the file
1421 autoconfiguration. 1388 autoconfiguration.
1422 Ranges are in pairs (memory base and size). 1389 Ranges are in pairs (memory base and size).
1423 1390
1391 print-fatal-signals=
1392 [KNL] debug: print fatal signals
1393 print-fatal-signals=1: print segfault info to
1394 the kernel console.
1395 default: off.
1396
1397 printk.time= Show timing data prefixed to each printk message line
1398 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1399
1424 profile= [KNL] Enable kernel profiling via /proc/profile 1400 profile= [KNL] Enable kernel profiling via /proc/profile
1425 Format: [schedule,]<number> 1401 Format: [schedule,]<number>
1426 Param: "schedule" - profile schedule points. 1402 Param: "schedule" - profile schedule points.
@@ -1533,6 +1509,10 @@ and is between 256 and 4096 characters. It is defined in the file
1533 1509
1534 rootfstype= [KNL] Set root filesystem type 1510 rootfstype= [KNL] Set root filesystem type
1535 1511
1512 rootwait [KNL] Wait (indefinitely) for root device to show up.
1513 Useful for devices that are detected asynchronously
1514 (e.g. USB and MMC devices).
1515
1536 rw [KNL] Mount root device read-write on boot 1516 rw [KNL] Mount root device read-write on boot
1537 1517
1538 S [KNL] Run init in single mode 1518 S [KNL] Run init in single mode
@@ -1545,11 +1525,6 @@ and is between 256 and 4096 characters. It is defined in the file
1545 1525
1546 sbni= [NET] Granch SBNI12 leased line adapter 1526 sbni= [NET] Granch SBNI12 leased line adapter
1547 1527
1548 sbpcd= [HW,CD] Soundblaster CD adapter
1549 Format: <io>,<type>
1550 See a comment before function sbpcd_setup() in
1551 drivers/cdrom/sbpcd.c.
1552
1553 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver 1528 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1554 Format: <io>[,<timeout>[,<isapnp>]] 1529 Format: <io>[,<timeout>[,<isapnp>]]
1555 1530
@@ -1602,41 +1577,41 @@ and is between 256 and 4096 characters. It is defined in the file
1602 simeth= [IA-64] 1577 simeth= [IA-64]
1603 simscsi= 1578 simscsi=
1604 1579
1605 sjcd= [HW,CD]
1606 Format: <io>,<irq>,<dma>
1607 See header of drivers/cdrom/sjcd.c.
1608
1609 slram= [HW,MTD] 1580 slram= [HW,MTD]
1610 1581
1611 slub_debug [MM, SLUB] 1582 slub_debug[=options[,slabs]] [MM, SLUB]
1612 Enabling slub_debug allows one to determine the culprit 1583 Enabling slub_debug allows one to determine the
1613 if slab objects become corrupted. Enabling slub_debug 1584 culprit if slab objects become corrupted. Enabling
1614 creates guard zones around objects and poisons objects 1585 slub_debug can create guard zones around objects and
1615 when not in use. Also tracks the last alloc / free. 1586 may poison objects when not in use. Also tracks the
1616 For more information see Documentation/vm/slub.txt. 1587 last alloc / free. For more information see
1588 Documentation/vm/slub.txt.
1617 1589
1618 slub_max_order= [MM, SLUB] 1590 slub_max_order= [MM, SLUB]
1619 Determines the maximum allowed order for slabs. Setting 1591 Determines the maximum allowed order for slabs.
1620 this too high may cause fragmentation. 1592 A high setting may cause OOMs due to memory
1621 For more information see Documentation/vm/slub.txt. 1593 fragmentation. For more information see
1594 Documentation/vm/slub.txt.
1622 1595
1623 slub_min_objects= [MM, SLUB] 1596 slub_min_objects= [MM, SLUB]
1624 The minimum objects per slab. SLUB will increase the 1597 The minimum number of objects per slab. SLUB will
1625 slab order up to slub_max_order to generate a 1598 increase the slab order up to slub_max_order to
1626 sufficiently big slab to satisfy the number of objects. 1599 generate a sufficiently large slab able to contain
1627 The higher the number of objects the smaller the overhead 1600 the number of objects indicated. The higher the number
1628 of tracking slabs. 1601 of objects the smaller the overhead of tracking slabs
1602 and the less frequently locks need to be acquired.
1629 For more information see Documentation/vm/slub.txt. 1603 For more information see Documentation/vm/slub.txt.
1630 1604
1631 slub_min_order= [MM, SLUB] 1605 slub_min_order= [MM, SLUB]
1632 Determines the mininum page order for slabs. Must be 1606 Determines the mininum page order for slabs. Must be
1633 lower than slub_max_order 1607 lower than slub_max_order.
1634 For more information see Documentation/vm/slub.txt. 1608 For more information see Documentation/vm/slub.txt.
1635 1609
1636 slub_nomerge [MM, SLUB] 1610 slub_nomerge [MM, SLUB]
1637 Disable merging of slabs of similar size. May be 1611 Disable merging of slabs with similar size. May be
1638 necessary if there is some reason to distinguish 1612 necessary if there is some reason to distinguish
1639 allocs to different slabs. 1613 allocs to different slabs. Debug options disable
1614 merging on their own.
1640 For more information see Documentation/vm/slub.txt. 1615 For more information see Documentation/vm/slub.txt.
1641 1616
1642 smart2= [HW] 1617 smart2= [HW]
@@ -1778,9 +1753,6 @@ and is between 256 and 4096 characters. It is defined in the file
1778 1753
1779 snd-ymfpci= [HW,ALSA] 1754 snd-ymfpci= [HW,ALSA]
1780 1755
1781 sonycd535= [HW,CD]
1782 Format: <io>[,<irq>]
1783
1784 sonypi.*= [HW] Sony Programmable I/O Control Device driver 1756 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1785 See Documentation/sonypi.txt 1757 See Documentation/sonypi.txt
1786 1758
@@ -1852,6 +1824,7 @@ and is between 256 and 4096 characters. It is defined in the file
1852 Set number of hash buckets for TCP connection 1824 Set number of hash buckets for TCP connection
1853 1825
1854 time Show timing data prefixed to each printk message line 1826 time Show timing data prefixed to each printk message line
1827 [deprecated, see 'printk.time']
1855 1828
1856 tipar.timeout= [HW,PPT] 1829 tipar.timeout= [HW,PPT]
1857 Set communications timeout in tenths of a second 1830 Set communications timeout in tenths of a second
@@ -1909,11 +1882,14 @@ and is between 256 and 4096 characters. It is defined in the file
1909 usbhid.mousepoll= 1882 usbhid.mousepoll=
1910 [USBHID] The interval which mice are to be polled at. 1883 [USBHID] The interval which mice are to be polled at.
1911 1884
1912 vdso= [IA-32,SH] 1885 vdso= [IA-32,SH,x86-64]
1913 vdso=2: enable compat VDSO (default with COMPAT_VDSO) 1886 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1914 vdso=1: enable VDSO (default) 1887 vdso=1: enable VDSO (default)
1915 vdso=0: disable VDSO mapping 1888 vdso=0: disable VDSO mapping
1916 1889
1890 vector= [IA-64,SMP]
1891 vector=percpu: enable percpu vector domain
1892
1917 video= [FB] Frame buffer configuration 1893 video= [FB] Frame buffer configuration
1918 See Documentation/fb/modedb.txt. 1894 See Documentation/fb/modedb.txt.
1919 1895