kernel-parameters.txt 83 KB

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991001011021031041051061071081091101111121131141151161171181191201211221231241251261271281291301311321331341351361371381391401411421431441451461471481491501511521531541551561571581591601611621631641651661671681691701711721731741751761771781791801811821831841851861871881891901911921931941951961971981992002012022032042052062072082092102112122132142152162172182192202212222232242252262272282292302312322332342352362372382392402412422432442452462472482492502512522532542552562572582592602612622632642652662672682692702712722732742752762772782792802812822832842852862872882892902912922932942952962972982993003013023033043053063073083093103113123133143153163173183193203213223233243253263273283293303313323333343353363373383393403413423433443453463473483493503513523533543553563573583593603613623633643653663673683693703713723733743753763773783793803813823833843853863873883893903913923933943953963973983994004014024034044054064074084094104114124134144154164174184194204214224234244254264274284294304314324334344354364374384394404414424434444454464474484494504514524534544554564574584594604614624634644654664674684694704714724734744754764774784794804814824834844854864874884894904914924934944954964974984995005015025035045055065075085095105115125135145155165175185195205215225235245255265275285295305315325335345355365375385395405415425435445455465475485495505515525535545555565575585595605615625635645655665675685695705715725735745755765775785795805815825835845855865875885895905915925935945955965975985996006016026036046056066076086096106116126136146156166176186196206216226236246256266276286296306316326336346356366376386396406416426436446456466476486496506516526536546556566576586596606616626636646656666676686696706716726736746756766776786796806816826836846856866876886896906916926936946956966976986997007017027037047057067077087097107117127137147157167177187197207217227237247257267277287297307317327337347357367377387397407417427437447457467477487497507517527537547557567577587597607617627637647657667677687697707717727737747757767777787797807817827837847857867877887897907917927937947957967977987998008018028038048058068078088098108118128138148158168178188198208218228238248258268278288298308318328338348358368378388398408418428438448458468478488498508518528538548558568578588598608618628638648658668678688698708718728738748758768778788798808818828838848858868878888898908918928938948958968978988999009019029039049059069079089099109119129139149159169179189199209219229239249259269279289299309319329339349359369379389399409419429439449459469479489499509519529539549559569579589599609619629639649659669679689699709719729739749759769779789799809819829839849859869879889899909919929939949959969979989991000100110021003100410051006100710081009101010111012101310141015101610171018101910201021102210231024102510261027102810291030103110321033103410351036103710381039104010411042104310441045104610471048104910501051105210531054105510561057105810591060106110621063106410651066106710681069107010711072107310741075107610771078107910801081108210831084108510861087108810891090109110921093109410951096109710981099110011011102110311041105110611071108110911101111111211131114111511161117111811191120112111221123112411251126112711281129113011311132113311341135113611371138113911401141114211431144114511461147114811491150115111521153115411551156115711581159116011611162116311641165116611671168116911701171117211731174117511761177117811791180118111821183118411851186118711881189119011911192119311941195119611971198119912001201120212031204120512061207120812091210121112121213121412151216121712181219122012211222122312241225122612271228122912301231123212331234123512361237123812391240124112421243124412451246124712481249125012511252125312541255125612571258125912601261126212631264126512661267126812691270127112721273127412751276127712781279128012811282128312841285128612871288128912901291129212931294129512961297129812991300130113021303130413051306130713081309131013111312131313141315131613171318131913201321132213231324132513261327132813291330133113321333133413351336133713381339134013411342134313441345134613471348134913501351135213531354135513561357135813591360136113621363136413651366136713681369137013711372137313741375137613771378137913801381138213831384138513861387138813891390139113921393139413951396139713981399140014011402140314041405140614071408140914101411141214131414141514161417141814191420142114221423142414251426142714281429143014311432143314341435143614371438143914401441144214431444144514461447144814491450145114521453145414551456145714581459146014611462146314641465146614671468146914701471147214731474147514761477147814791480148114821483148414851486148714881489149014911492149314941495149614971498149915001501150215031504150515061507150815091510151115121513151415151516151715181519152015211522152315241525152615271528152915301531153215331534153515361537153815391540154115421543154415451546154715481549155015511552155315541555155615571558155915601561156215631564156515661567156815691570157115721573157415751576157715781579158015811582158315841585158615871588158915901591159215931594159515961597159815991600160116021603160416051606160716081609161016111612161316141615161616171618161916201621162216231624162516261627162816291630163116321633163416351636163716381639164016411642164316441645164616471648164916501651165216531654165516561657165816591660166116621663166416651666166716681669167016711672167316741675167616771678167916801681168216831684168516861687168816891690169116921693169416951696169716981699170017011702170317041705170617071708170917101711171217131714171517161717171817191720172117221723172417251726172717281729173017311732173317341735173617371738173917401741174217431744174517461747174817491750175117521753175417551756175717581759176017611762176317641765176617671768176917701771177217731774177517761777177817791780178117821783178417851786178717881789179017911792179317941795179617971798179918001801180218031804180518061807180818091810181118121813181418151816181718181819182018211822182318241825182618271828182918301831183218331834183518361837183818391840184118421843184418451846184718481849185018511852185318541855185618571858185918601861186218631864186518661867186818691870187118721873187418751876187718781879188018811882188318841885188618871888188918901891189218931894189518961897189818991900190119021903190419051906190719081909191019111912191319141915191619171918191919201921192219231924192519261927192819291930193119321933193419351936193719381939194019411942194319441945194619471948194919501951195219531954195519561957195819591960196119621963196419651966196719681969197019711972197319741975197619771978197919801981198219831984198519861987198819891990199119921993199419951996199719981999200020012002200320042005200620072008200920102011201220132014201520162017201820192020202120222023202420252026202720282029203020312032203320342035203620372038203920402041204220432044204520462047204820492050205120522053205420552056205720582059206020612062206320642065206620672068206920702071207220732074207520762077207820792080208120822083208420852086208720882089209020912092209320942095209620972098209921002101210221032104210521062107210821092110211121122113211421152116211721182119212021212122212321242125212621272128212921302131213221332134213521362137213821392140214121422143214421452146214721482149215021512152215321542155215621572158215921602161216221632164216521662167216821692170217121722173217421752176217721782179218021812182218321842185218621872188218921902191219221932194219521962197219821992200220122022203220422052206220722082209221022112212221322142215221622172218221922202221222222232224222522262227222822292230223122322233223422352236223722382239224022412242224322442245224622472248224922502251225222532254225522562257225822592260226122622263226422652266226722682269227022712272227322742275227622772278227922802281228222832284228522862287228822892290229122922293229422952296229722982299230023012302230323042305230623072308230923102311231223132314231523162317231823192320232123222323232423252326232723282329233023312332233323342335233623372338233923402341234223432344234523462347234823492350235123522353235423552356235723582359236023612362236323642365236623672368236923702371237223732374237523762377237823792380238123822383238423852386238723882389239023912392239323942395239623972398239924002401240224032404240524062407240824092410241124122413241424152416241724182419242024212422242324242425242624272428242924302431243224332434243524362437243824392440244124422443244424452446244724482449245024512452245324542455245624572458245924602461246224632464246524662467246824692470247124722473247424752476247724782479248024812482248324842485248624872488248924902491249224932494249524962497249824992500250125022503250425052506250725082509251025112512251325142515251625172518251925202521252225232524252525262527252825292530253125322533253425352536253725382539254025412542254325442545254625472548254925502551255225532554255525562557255825592560256125622563256425652566256725682569257025712572257325742575257625772578257925802581258225832584258525862587258825892590259125922593259425952596259725982599260026012602260326042605260626072608260926102611261226132614261526162617
  1. Kernel Parameters
  2. ~~~~~~~~~~~~~~~~~
  3. The following is a consolidated list of the kernel parameters as implemented
  4. (mostly) by the __setup() macro and sorted into English Dictionary order
  5. (defined as ignoring all punctuation and sorting digits before letters in a
  6. case insensitive manner), and with descriptions where known.
  7. Module parameters for loadable modules are specified only as the
  8. parameter name with optional '=' and value as appropriate, such as:
  9. modprobe usbcore blinkenlights=1
  10. Module parameters for modules that are built into the kernel image
  11. are specified on the kernel command line with the module name plus
  12. '.' plus parameter name, with '=' and value if appropriate, such as:
  13. usbcore.blinkenlights=1
  14. Hyphens (dashes) and underscores are equivalent in parameter names, so
  15. log_buf_len=1M print-fatal-signals=1
  16. can also be entered as
  17. log-buf-len=1M print_fatal_signals=1
  18. This document may not be entirely up to date and comprehensive. The command
  19. "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
  20. module. Loadable modules, after being loaded into the running kernel, also
  21. reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
  22. parameters may be changed at runtime by the command
  23. "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
  24. The parameters listed below are only valid if certain kernel build options were
  25. enabled and if respective hardware is present. The text in square brackets at
  26. the beginning of each description states the restrictions within which a
  27. parameter is applicable:
  28. ACPI ACPI support is enabled.
  29. AGP AGP (Accelerated Graphics Port) is enabled.
  30. ALSA ALSA sound support is enabled.
  31. APIC APIC support is enabled.
  32. APM Advanced Power Management support is enabled.
  33. AVR32 AVR32 architecture is enabled.
  34. AX25 Appropriate AX.25 support is enabled.
  35. BLACKFIN Blackfin architecture is enabled.
  36. DRM Direct Rendering Management support is enabled.
  37. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
  38. EFI EFI Partitioning (GPT) is enabled
  39. EIDE EIDE/ATAPI support is enabled.
  40. FB The frame buffer device is enabled.
  41. HW Appropriate hardware is enabled.
  42. IA-64 IA-64 architecture is enabled.
  43. IMA Integrity measurement architecture is enabled.
  44. IOSCHED More than one I/O scheduler is enabled.
  45. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  46. ISAPNP ISA PnP code is enabled.
  47. ISDN Appropriate ISDN support is enabled.
  48. JOY Appropriate joystick support is enabled.
  49. LIBATA Libata driver is enabled
  50. LP Printer support is enabled.
  51. LOOP Loopback device support is enabled.
  52. M68k M68k architecture is enabled.
  53. These options have more detailed description inside of
  54. Documentation/m68k/kernel-options.txt.
  55. MCA MCA bus support is enabled.
  56. MDA MDA console support is enabled.
  57. MOUSE Appropriate mouse support is enabled.
  58. MSI Message Signaled Interrupts (PCI).
  59. MTD MTD (Memory Technology Device) support is enabled.
  60. NET Appropriate network support is enabled.
  61. NUMA NUMA support is enabled.
  62. GENERIC_TIME The generic timeofday code is enabled.
  63. NFS Appropriate NFS support is enabled.
  64. OSS OSS sound support is enabled.
  65. PV_OPS A paravirtualized kernel is enabled.
  66. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  67. PARISC The PA-RISC architecture is enabled.
  68. PCI PCI bus support is enabled.
  69. PCIE PCI Express support is enabled.
  70. PCMCIA The PCMCIA subsystem is enabled.
  71. PNP Plug & Play support is enabled.
  72. PPC PowerPC architecture is enabled.
  73. PPT Parallel port support is enabled.
  74. PS2 Appropriate PS/2 support is enabled.
  75. RAM RAM disk support is enabled.
  76. ROOTPLUG The example Root Plug LSM is enabled.
  77. S390 S390 architecture is enabled.
  78. SCSI Appropriate SCSI support is enabled.
  79. A lot of drivers has their options described inside of
  80. Documentation/scsi/.
  81. SECURITY Different security models are enabled.
  82. SELINUX SELinux support is enabled.
  83. SERIAL Serial support is enabled.
  84. SH SuperH architecture is enabled.
  85. SMP The kernel is an SMP kernel.
  86. SPARC Sparc architecture is enabled.
  87. SWSUSP Software suspend (hibernation) is enabled.
  88. SUSPEND System suspend states are enabled.
  89. FTRACE Function tracing enabled.
  90. TS Appropriate touchscreen support is enabled.
  91. UMS USB Mass Storage support is enabled.
  92. USB USB support is enabled.
  93. USBHID USB Human Interface Device support is enabled.
  94. V4L Video For Linux support is enabled.
  95. VGA The VGA console has been enabled.
  96. VT Virtual terminal support is enabled.
  97. WDT Watchdog support is enabled.
  98. XT IBM PC/XT MFM hard disk support is enabled.
  99. X86-32 X86-32, aka i386 architecture is enabled.
  100. X86-64 X86-64 architecture is enabled.
  101. More X86-64 boot options can be found in
  102. Documentation/x86/x86_64/boot-options.txt .
  103. X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
  104. In addition, the following text indicates that the option:
  105. BUGS= Relates to possible processor bugs on the said processor.
  106. KNL Is a kernel start-up parameter.
  107. BOOT Is a boot loader parameter.
  108. Parameters denoted with BOOT are actually interpreted by the boot
  109. loader, and have no meaning to the kernel directly.
  110. Do not modify the syntax of boot loader parameters without extreme
  111. need or coordination with <Documentation/x86/boot.txt>.
  112. There are also arch-specific kernel-parameters not documented here.
  113. See for example <Documentation/x86/x86_64/boot-options.txt>.
  114. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  115. a trailing = on the name of any parameter states that that parameter will
  116. be entered as an environment variable, whereas its absence indicates that
  117. it will appear as a kernel argument readable via /proc/cmdline by programs
  118. running once the system is up.
  119. The number of kernel parameters is not limited, but the length of the
  120. complete command line (parameters including spaces etc.) is limited to
  121. a fixed number of characters. This limit depends on the architecture
  122. and is between 256 and 4096 characters. It is defined in the file
  123. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  124. acpi= [HW,ACPI,X86]
  125. Advanced Configuration and Power Interface
  126. Format: { force | off | ht | strict | noirq | rsdt }
  127. force -- enable ACPI if default was off
  128. off -- disable ACPI if default was on
  129. noirq -- do not use ACPI for IRQ routing
  130. ht -- run only enough ACPI to enable Hyper Threading
  131. strict -- Be less tolerant of platforms that are not
  132. strictly ACPI specification compliant.
  133. rsdt -- prefer RSDT over (default) XSDT
  134. See also Documentation/power/pm.txt, pci=noacpi
  135. acpi_apic_instance= [ACPI, IOAPIC]
  136. Format: <int>
  137. 2: use 2nd APIC table, if available
  138. 1,0: use 1st APIC table
  139. default: 0
  140. acpi_backlight= [HW,ACPI]
  141. acpi_backlight=vendor
  142. acpi_backlight=video
  143. If set to vendor, prefer vendor specific driver
  144. (e.g. thinkpad_acpi, sony_acpi, etc.) instead
  145. of the ACPI video.ko driver.
  146. acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
  147. acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
  148. Format: <int>
  149. CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
  150. debug output. Bits in debug_layer correspond to a
  151. _COMPONENT in an ACPI source file, e.g.,
  152. #define _COMPONENT ACPI_PCI_COMPONENT
  153. Bits in debug_level correspond to a level in
  154. ACPI_DEBUG_PRINT statements, e.g.,
  155. ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
  156. The debug_level mask defaults to "info". See
  157. Documentation/acpi/debug.txt for more information about
  158. debug layers and levels.
  159. Enable processor driver info messages:
  160. acpi.debug_layer=0x20000000
  161. Enable PCI/PCI interrupt routing info messages:
  162. acpi.debug_layer=0x400000
  163. Enable AML "Debug" output, i.e., stores to the Debug
  164. object while interpreting AML:
  165. acpi.debug_layer=0xffffffff acpi.debug_level=0x2
  166. Enable all messages related to ACPI hardware:
  167. acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
  168. Some values produce so much output that the system is
  169. unusable. The "log_buf_len" parameter may be useful
  170. if you need to capture more output.
  171. acpi_display_output= [HW,ACPI]
  172. acpi_display_output=vendor
  173. acpi_display_output=video
  174. See above.
  175. acpi_irq_balance [HW,ACPI]
  176. ACPI will balance active IRQs
  177. default in APIC mode
  178. acpi_irq_nobalance [HW,ACPI]
  179. ACPI will not move active IRQs (default)
  180. default in PIC mode
  181. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  182. Format: <irq>,<irq>...
  183. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  184. use by PCI
  185. Format: <irq>,<irq>...
  186. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  187. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  188. Format: To spoof as Windows 98: ="Microsoft Windows"
  189. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  190. acpi_osi="string1" # add string1 -- only one string
  191. acpi_osi="!string2" # remove built-in string2
  192. acpi_osi= # disable all strings
  193. acpi_pm_good [X86]
  194. Override the pmtimer bug detection: force the kernel
  195. to assume that this machine's pmtimer latches its value
  196. and always returns good values.
  197. acpi.power_nocheck= [HW,ACPI]
  198. Format: 1/0 enable/disable the check of power state.
  199. On some bogus BIOS the _PSC object/_STA object of
  200. power resource can't return the correct device power
  201. state. In such case it is unneccessary to check its
  202. power state again in power transition.
  203. 1 : disable the power state check
  204. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  205. Format: { level | edge | high | low }
  206. acpi_serialize [HW,ACPI] force serialization of AML methods
  207. acpi_skip_timer_override [HW,ACPI]
  208. Recognize and ignore IRQ0/pin2 Interrupt Override.
  209. For broken nForce2 BIOS resulting in XT-PIC timer.
  210. acpi_sleep= [HW,ACPI] Sleep options
  211. Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
  212. old_ordering, s4_nonvs }
  213. See Documentation/power/video.txt for information on
  214. s3_bios and s3_mode.
  215. s3_beep is for debugging; it makes the PC's speaker beep
  216. as soon as the kernel's real-mode entry point is called.
  217. s4_nohwsig prevents ACPI hardware signature from being
  218. used during resume from hibernation.
  219. old_ordering causes the ACPI 1.0 ordering of the _PTS
  220. control method, with respect to putting devices into
  221. low power states, to be enforced (the ACPI 2.0 ordering
  222. of _PTS is used by default).
  223. s4_nonvs prevents the kernel from saving/restoring the
  224. ACPI NVS memory during hibernation.
  225. acpi_use_timer_override [HW,ACPI]
  226. Use timer override. For some broken Nvidia NF5 boards
  227. that require a timer override, but don't have HPET
  228. acpi_enforce_resources= [ACPI]
  229. { strict | lax | no }
  230. Check for resource conflicts between native drivers
  231. and ACPI OperationRegions (SystemIO and SystemMemory
  232. only). IO ports and memory declared in ACPI might be
  233. used by the ACPI subsystem in arbitrary AML code and
  234. can interfere with legacy drivers.
  235. strict (default): access to resources claimed by ACPI
  236. is denied; legacy drivers trying to access reserved
  237. resources will fail to bind to device using them.
  238. lax: access to resources claimed by ACPI is allowed;
  239. legacy drivers trying to access reserved resources
  240. will bind successfully but a warning message is logged.
  241. no: ACPI OperationRegions are not marked as reserved,
  242. no further checks are performed.
  243. ad1848= [HW,OSS]
  244. Format: <io>,<irq>,<dma>,<dma2>,<type>
  245. add_efi_memmap [EFI; X86] Include EFI memory map in
  246. kernel's map of available physical RAM.
  247. advansys= [HW,SCSI]
  248. See header of drivers/scsi/advansys.c.
  249. advwdt= [HW,WDT] Advantech WDT
  250. Format: <iostart>,<iostop>
  251. aedsp16= [HW,OSS] Audio Excel DSP 16
  252. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  253. See also header of sound/oss/aedsp16.c.
  254. agp= [AGP]
  255. { off | try_unsupported }
  256. off: disable AGP support
  257. try_unsupported: try to drive unsupported chipsets
  258. (may crash computer or cause data corruption)
  259. aha152x= [HW,SCSI]
  260. See Documentation/scsi/aha152x.txt.
  261. aha1542= [HW,SCSI]
  262. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  263. aic7xxx= [HW,SCSI]
  264. See Documentation/scsi/aic7xxx.txt.
  265. aic79xx= [HW,SCSI]
  266. See Documentation/scsi/aic79xx.txt.
  267. amd_iommu= [HW,X86-84]
  268. Pass parameters to the AMD IOMMU driver in the system.
  269. Possible values are:
  270. isolate - enable device isolation (each device, as far
  271. as possible, will get its own protection
  272. domain) [default]
  273. share - put every device behind one IOMMU into the
  274. same protection domain
  275. fullflush - enable flushing of IO/TLB entries when
  276. they are unmapped. Otherwise they are
  277. flushed before they will be reused, which
  278. is a lot of faster
  279. amijoy.map= [HW,JOY] Amiga joystick support
  280. Map of devices attached to JOY0DAT and JOY1DAT
  281. Format: <a>,<b>
  282. See also Documentation/kernel/input/joystick.txt
  283. analog.map= [HW,JOY] Analog joystick and gamepad support
  284. Specifies type or capabilities of an analog joystick
  285. connected to one of 16 gameports
  286. Format: <type1>,<type2>,..<type16>
  287. apc= [HW,SPARC]
  288. Power management functions (SPARCstation-4/5 + deriv.)
  289. Format: noidle
  290. Disable APC CPU standby support. SPARCstation-Fox does
  291. not play well with APC CPU idle - disable it if you have
  292. APC and your system crashes randomly.
  293. apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
  294. Change the output verbosity whilst booting
  295. Format: { quiet (default) | verbose | debug }
  296. Change the amount of debugging information output
  297. when initialising the APIC and IO-APIC components.
  298. apm= [APM] Advanced Power Management
  299. See header of arch/x86/kernel/apm_32.c.
  300. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  301. Format: <io>,<irq>,<nodeID>
  302. ataflop= [HW,M68k]
  303. atarimouse= [HW,MOUSE] Atari Mouse
  304. atascsi= [HW,SCSI] Atari SCSI
  305. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  306. EzKey and similar keyboards
  307. atkbd.reset= [HW] Reset keyboard during initialization
  308. atkbd.set= [HW] Select keyboard code set
  309. Format: <int> (2 = AT (default), 3 = PS/2)
  310. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  311. keyboards
  312. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  313. Format: <bool> (0 = real, 1 = synthetic (default))
  314. atkbd.softrepeat= [HW]
  315. Use software keyboard repeat
  316. autotest [IA64]
  317. baycom_epp= [HW,AX25]
  318. Format: <io>,<mode>
  319. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  320. Format: <io>,<mode>
  321. See header of drivers/net/hamradio/baycom_par.c.
  322. baycom_ser_fdx= [HW,AX25]
  323. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  324. Format: <io>,<irq>,<mode>[,<baud>]
  325. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  326. baycom_ser_hdx= [HW,AX25]
  327. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  328. Format: <io>,<irq>,<mode>
  329. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  330. boot_delay= Milliseconds to delay each printk during boot.
  331. Values larger than 10 seconds (10000) are changed to
  332. no delay (0).
  333. Format: integer
  334. bootmem_debug [KNL] Enable bootmem allocator debug messages.
  335. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  336. bttv.radio= Most important insmod options are available as
  337. kernel args too.
  338. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  339. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  340. BusLogic= [HW,SCSI]
  341. See drivers/scsi/BusLogic.c, comment before function
  342. BusLogic_ParseDriverOptions().
  343. c101= [NET] Moxa C101 synchronous serial card
  344. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  345. Sometimes CPU hardware bugs make them report the cache
  346. size incorrectly. The kernel will attempt work arounds
  347. to fix known problems, but for some CPUs it is not
  348. possible to determine what the correct size should be.
  349. This option provides an override for these situations.
  350. capability.disable=
  351. [SECURITY] Disable capabilities. This would normally
  352. be used only if an alternative security model is to be
  353. configured. Potentially dangerous and should only be
  354. used if you are entirely sure of the consequences.
  355. ccw_timeout_log [S390]
  356. See Documentation/s390/CommonIO for details.
  357. cgroup_disable= [KNL] Disable a particular controller
  358. Format: {name of the controller(s) to disable}
  359. {Currently supported controllers - "memory"}
  360. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  361. Format: { "0" | "1" }
  362. See security/selinux/Kconfig help text.
  363. 0 -- check protection applied by kernel (includes
  364. any implied execute protection).
  365. 1 -- check protection requested by application.
  366. Default value is set via a kernel config option.
  367. Value can be changed at runtime via
  368. /selinux/checkreqprot.
  369. cio_ignore= [S390]
  370. See Documentation/s390/CommonIO for details.
  371. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  372. [Deprecated]
  373. Forces specified clocksource (if available) to be used
  374. when calculating gettimeofday(). If specified
  375. clocksource is not available, it defaults to PIT.
  376. Format: { pit | tsc | cyclone | pmtmr }
  377. clocksource= [GENERIC_TIME] Override the default clocksource
  378. Format: <string>
  379. Override the default clocksource and use the clocksource
  380. with the name specified.
  381. Some clocksource names to choose from, depending on
  382. the platform:
  383. [all] jiffies (this is the base, fallback clocksource)
  384. [ACPI] acpi_pm
  385. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  386. pxa_timer,timer3,32k_counter,timer0_1
  387. [AVR32] avr32
  388. [X86-32] pit,hpet,tsc,vmi-timer;
  389. scx200_hrt on Geode; cyclone on IBM x440
  390. [MIPS] MIPS
  391. [PARISC] cr16
  392. [S390] tod
  393. [SH] SuperH
  394. [SPARC64] tick
  395. [X86-64] hpet,tsc
  396. clearcpuid=BITNUM [X86]
  397. Disable CPUID feature X for the kernel. See
  398. arch/x86/include/asm/cpufeature.h for the valid bit
  399. numbers. Note the Linux specific bits are not necessarily
  400. stable over kernel options, but the vendor specific
  401. ones should be.
  402. Also note that user programs calling CPUID directly
  403. or using the feature without checking anything
  404. will still see it. This just prevents it from
  405. being used by the kernel or shown in /proc/cpuinfo.
  406. Also note the kernel might malfunction if you disable
  407. some critical bits.
  408. code_bytes [X86] How many bytes of object code to print
  409. in an oops report.
  410. Range: 0 - 8192
  411. Default: 64
  412. com20020= [HW,NET] ARCnet - COM20020 chipset
  413. Format:
  414. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  415. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  416. Format: <io>[,<irq>]
  417. com90xx= [HW,NET]
  418. ARCnet - COM90xx chipset (memory-mapped buffers)
  419. Format: <io>[,<irq>[,<memstart>]]
  420. condev= [HW,S390] console device
  421. conmode=
  422. console= [KNL] Output console device and options.
  423. tty<n> Use the virtual console device <n>.
  424. ttyS<n>[,options]
  425. ttyUSB0[,options]
  426. Use the specified serial port. The options are of
  427. the form "bbbbpnf", where "bbbb" is the baud rate,
  428. "p" is parity ("n", "o", or "e"), "n" is number of
  429. bits, and "f" is flow control ("r" for RTS or
  430. omit it). Default is "9600n8".
  431. See Documentation/serial-console.txt for more
  432. information. See
  433. Documentation/networking/netconsole.txt for an
  434. alternative.
  435. uart[8250],io,<addr>[,options]
  436. uart[8250],mmio,<addr>[,options]
  437. Start an early, polled-mode console on the 8250/16550
  438. UART at the specified I/O port or MMIO address,
  439. switching to the matching ttyS device later. The
  440. options are the same as for ttyS, above.
  441. If the device connected to the port is not a TTY but a braille
  442. device, prepend "brl," before the device type, for instance
  443. console=brl,ttyS0
  444. For now, only VisioBraille is supported.
  445. coredump_filter=
  446. [KNL] Change the default value for
  447. /proc/<pid>/coredump_filter.
  448. See also Documentation/filesystems/proc.txt.
  449. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  450. Format:
  451. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  452. crashkernel=nn[KMG]@ss[KMG]
  453. [KNL] Reserve a chunk of physical memory to
  454. hold a kernel to switch to with kexec on panic.
  455. crashkernel=range1:size1[,range2:size2,...][@offset]
  456. [KNL] Same as above, but depends on the memory
  457. in the running system. The syntax of range is
  458. start-[end] where start and end are both
  459. a memory unit (amount[KMG]). See also
  460. Documentation/kdump/kdump.txt for a example.
  461. cs89x0_dma= [HW,NET]
  462. Format: <dma>
  463. cs89x0_media= [HW,NET]
  464. Format: { rj45 | aui | bnc }
  465. dasd= [HW,NET]
  466. See header of drivers/s390/block/dasd_devmap.c.
  467. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  468. (one device per port)
  469. Format: <port#>,<type>
  470. See also Documentation/input/joystick-parport.txt
  471. debug [KNL] Enable kernel debugging (events log level).
  472. debug_locks_verbose=
  473. [KNL] verbose self-tests
  474. Format=<0|1>
  475. Print debugging info while doing the locking API
  476. self-tests.
  477. We default to 0 (no extra messages), setting it to
  478. 1 will print _a lot_ more information - normally
  479. only useful to kernel developers.
  480. debug_objects [KNL] Enable object debugging
  481. no_debug_objects
  482. [KNL] Disable object debugging
  483. debugpat [X86] Enable PAT debugging
  484. decnet.addr= [HW,NET]
  485. Format: <area>[,<node>]
  486. See also Documentation/networking/decnet.txt.
  487. default_hugepagesz=
  488. [same as hugepagesz=] The size of the default
  489. HugeTLB page size. This is the size represented by
  490. the legacy /proc/ hugepages APIs, used for SHM, and
  491. default size when mounting hugetlbfs filesystems.
  492. Defaults to the default architecture's huge page size
  493. if not specified.
  494. dhash_entries= [KNL]
  495. Set number of hash buckets for dentry cache.
  496. digi= [HW,SERIAL]
  497. IO parameters + enable/disable command.
  498. digiepca= [HW,SERIAL]
  499. See drivers/char/README.epca and
  500. Documentation/serial/digiepca.txt.
  501. disable_mtrr_cleanup [X86]
  502. The kernel tries to adjust MTRR layout from continuous
  503. to discrete, to make X server driver able to add WB
  504. entry later. This parameter disables that.
  505. disable_mtrr_trim [X86, Intel and AMD only]
  506. By default the kernel will trim any uncacheable
  507. memory out of your available memory pool based on
  508. MTRR settings. This parameter disables that behavior,
  509. possibly causing your machine to run very slowly.
  510. disable_timer_pin_1 [X86]
  511. Disable PIN 1 of APIC timer
  512. Can be useful to work around chipset bugs.
  513. dmasound= [HW,OSS] Sound subsystem buffers
  514. dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
  515. this option disables the debugging code at boot.
  516. dma_debug_entries=<number>
  517. This option allows to tune the number of preallocated
  518. entries for DMA-API debugging code. One entry is
  519. required per DMA-API allocation. Use this if the
  520. DMA-API debugging code disables itself because the
  521. architectural default is too low.
  522. dma_debug_driver=<driver_name>
  523. With this option the DMA-API debugging driver
  524. filter feature can be enabled at boot time. Just
  525. pass the driver to filter for as the parameter.
  526. The filter can be disabled or changed to another
  527. driver later using sysfs.
  528. dscc4.setup= [NET]
  529. dtc3181e= [HW,SCSI]
  530. dynamic_printk Enables pr_debug()/dev_dbg() calls if
  531. CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
  532. These can also be switched on/off via
  533. <debugfs>/dynamic_printk/modules
  534. earlycon= [KNL] Output early console device and options.
  535. uart[8250],io,<addr>[,options]
  536. uart[8250],mmio,<addr>[,options]
  537. Start an early, polled-mode console on the 8250/16550
  538. UART at the specified I/O port or MMIO address.
  539. The options are the same as for ttyS, above.
  540. earlyprintk= [X86,SH,BLACKFIN]
  541. earlyprintk=vga
  542. earlyprintk=serial[,ttySn[,baudrate]]
  543. earlyprintk=dbgp
  544. Append ",keep" to not disable it when the real console
  545. takes over.
  546. Only vga or serial or usb debug port at a time.
  547. Currently only ttyS0 and ttyS1 are supported.
  548. Interaction with the standard serial driver is not
  549. very good.
  550. The VGA output is eventually overwritten by the real
  551. console.
  552. eata= [HW,SCSI]
  553. edd= [EDD]
  554. Format: {"off" | "on" | "skip[mbr]"}
  555. eisa_irq_edge= [PARISC,HW]
  556. See header of drivers/parisc/eisa.c.
  557. elanfreq= [X86-32]
  558. See comment before function elanfreq_setup() in
  559. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
  560. elevator= [IOSCHED]
  561. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  562. See Documentation/block/as-iosched.txt and
  563. Documentation/block/deadline-iosched.txt for details.
  564. elfcorehdr= [IA64,PPC,SH,X86]
  565. Specifies physical address of start of kernel core
  566. image elf header. Generally kexec loader will
  567. pass this option to capture kernel.
  568. See Documentation/kdump/kdump.txt for details.
  569. enable_mtrr_cleanup [X86]
  570. The kernel tries to adjust MTRR layout from continuous
  571. to discrete, to make X server driver able to add WB
  572. entry later. This parameter enables that.
  573. enable_timer_pin_1 [X86]
  574. Enable PIN 1 of APIC timer
  575. Can be useful to work around chipset bugs
  576. (in particular on some ATI chipsets).
  577. The kernel tries to set a reasonable default.
  578. enforcing [SELINUX] Set initial enforcing status.
  579. Format: {"0" | "1"}
  580. See security/selinux/Kconfig help text.
  581. 0 -- permissive (log only, no denials).
  582. 1 -- enforcing (deny and log).
  583. Default value is 0.
  584. Value can be changed at runtime via /selinux/enforce.
  585. ether= [HW,NET] Ethernet cards parameters
  586. This option is obsoleted by the "netdev=" option, which
  587. has equivalent usage. See its documentation for details.
  588. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  589. Format: <io>[,<irq>]
  590. failslab=
  591. fail_page_alloc=
  592. fail_make_request=[KNL]
  593. General fault injection mechanism.
  594. Format: <interval>,<probability>,<space>,<times>
  595. See also /Documentation/fault-injection/.
  596. fd_mcs= [HW,SCSI]
  597. See header of drivers/scsi/fd_mcs.c.
  598. fdomain= [HW,SCSI]
  599. See header of drivers/scsi/fdomain.c.
  600. floppy= [HW]
  601. See Documentation/blockdev/floppy.txt.
  602. force_pal_cache_flush
  603. [IA-64] Avoid check_sal_cache_flush which may hang on
  604. buggy SAL_CACHE_FLUSH implementations. Using this
  605. parameter will force ia64_sal_cache_flush to call
  606. ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
  607. ftrace=[tracer]
  608. [FTRACE] will set and start the specified tracer
  609. as early as possible in order to facilitate early
  610. boot debugging.
  611. ftrace_dump_on_oops
  612. [FTRACE] will dump the trace buffers on oops.
  613. ftrace_filter=[function-list]
  614. [FTRACE] Limit the functions traced by the function
  615. tracer at boot up. function-list is a comma separated
  616. list of functions. This list can be changed at run
  617. time by the set_ftrace_filter file in the debugfs
  618. tracing directory.
  619. ftrace_notrace=[function-list]
  620. [FTRACE] Do not trace the functions specified in
  621. function-list. This list can be changed at run time
  622. by the set_ftrace_notrace file in the debugfs
  623. tracing directory.
  624. gamecon.map[2|3]=
  625. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  626. support via parallel port (up to 5 devices per port)
  627. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  628. See also Documentation/input/joystick-parport.txt
  629. gamma= [HW,DRM]
  630. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  631. Format: off | on
  632. default: on
  633. gdth= [HW,SCSI]
  634. See header of drivers/scsi/gdth.c.
  635. gpt [EFI] Forces disk with valid GPT signature but
  636. invalid Protective MBR to be treated as GPT.
  637. gvp11= [HW,SCSI]
  638. hashdist= [KNL,NUMA] Large hashes allocated during boot
  639. are distributed across NUMA nodes. Defaults on
  640. for 64bit NUMA, off otherwise.
  641. Format: 0 | 1 (for off | on)
  642. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  643. hd= [EIDE] (E)IDE hard drive subsystem geometry
  644. Format: <cyl>,<head>,<sect>
  645. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  646. size of <nn>. This works even on boxes that have no
  647. highmem otherwise. This also works to reduce highmem
  648. size on bigger boxes.
  649. highres= [KNL] Enable/disable high resolution timer mode.
  650. Valid parameters: "on", "off"
  651. Default: "on"
  652. hisax= [HW,ISDN]
  653. See Documentation/isdn/README.HiSax.
  654. hlt [BUGS=ARM,SH]
  655. hpet= [X86-32,HPET] option to control HPET usage
  656. Format: { enable (default) | disable | force |
  657. verbose }
  658. disable: disable HPET and use PIT instead
  659. force: allow force enabled of undocumented chips (ICH4,
  660. VIA, nVidia)
  661. verbose: show contents of HPET registers during setup
  662. hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
  663. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
  664. On x86-64 and powerpc, this option can be specified
  665. multiple times interleaved with hugepages= to reserve
  666. huge pages of different sizes. Valid pages sizes on
  667. x86-64 are 2M (when the CPU supports "pse") and 1G
  668. (when the CPU supports the "pdpe1gb" cpuinfo flag)
  669. Note that 1GB pages can only be allocated at boot time
  670. using hugepages= and not freed afterwards.
  671. hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
  672. terminal devices. Valid values: 0..8
  673. hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
  674. If specified, z/VM IUCV HVC accepts connections
  675. from listed z/VM user IDs only.
  676. i2c_bus= [HW] Override the default board specific I2C bus speed
  677. or register an additional I2C bus that is not
  678. registered from board initialization code.
  679. Format:
  680. <bus_id>,<clkrate>
  681. i8042.debug [HW] Toggle i8042 debug mode
  682. i8042.direct [HW] Put keyboard port into non-translated mode
  683. i8042.dumbkbd [HW] Pretend that controller can only read data from
  684. keyboard and cannot control its state
  685. (Don't attempt to blink the leds)
  686. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  687. i8042.nokbd [HW] Don't check/create keyboard port
  688. i8042.noloop [HW] Disable the AUX Loopback command while probing
  689. for the AUX port
  690. i8042.nomux [HW] Don't check presence of an active multiplexing
  691. controller
  692. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  693. controllers
  694. i8042.panicblink=
  695. [HW] Frequency with which keyboard LEDs should blink
  696. when kernel panics (default is 0.5 sec)
  697. i8042.reset [HW] Reset the controller during init and cleanup
  698. i8042.unlock [HW] Unlock (ignore) the keylock
  699. i810= [HW,DRM]
  700. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  701. indicates that the driver is running on unsupported
  702. hardware.
  703. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  704. does not match list of supported models.
  705. i8k.power_status
  706. [HW] Report power status in /proc/i8k
  707. (disabled by default)
  708. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  709. capability is set.
  710. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  711. See Documentation/mca.txt.
  712. icn= [HW,ISDN]
  713. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  714. ide-core.nodma= [HW] (E)IDE subsystem
  715. Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
  716. .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
  717. .chs .ignore_cable are additional options
  718. See Documentation/ide/ide.txt.
  719. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  720. See Documentation/ide/ide.txt.
  721. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  722. Claim all unknown PCI IDE storage controllers.
  723. idle= [X86]
  724. Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
  725. Poll forces a polling idle loop that can slightly
  726. improve the performance of waking up a idle CPU, but
  727. will use a lot of power and make the system run hot.
  728. Not recommended.
  729. idle=mwait: On systems which support MONITOR/MWAIT but
  730. the kernel chose to not use it because it doesn't save
  731. as much power as a normal idle loop, use the
  732. MONITOR/MWAIT idle loop anyways. Performance should be
  733. the same as idle=poll.
  734. idle=halt: Halt is forced to be used for CPU idle.
  735. In such case C2/C3 won't be used again.
  736. idle=nomwait: Disable mwait for CPU C-states
  737. ignore_loglevel [KNL]
  738. Ignore loglevel setting - this will print /all/
  739. kernel messages to the console. Useful for debugging.
  740. ihash_entries= [KNL]
  741. Set number of hash buckets for inode cache.
  742. ima_audit= [IMA]
  743. Format: { "0" | "1" }
  744. 0 -- integrity auditing messages. (Default)
  745. 1 -- enable informational integrity auditing messages.
  746. ima_hash= [IMA]
  747. Formt: { "sha1" | "md5" }
  748. default: "sha1"
  749. ima_tcb [IMA]
  750. Load a policy which meets the needs of the Trusted
  751. Computing Base. This means IMA will measure all
  752. programs exec'd, files mmap'd for exec, and all files
  753. opened for read by uid=0.
  754. in2000= [HW,SCSI]
  755. See header of drivers/scsi/in2000.c.
  756. init= [KNL]
  757. Format: <full_path>
  758. Run specified binary instead of /sbin/init as init
  759. process.
  760. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  761. for working out where the kernel is dying during
  762. startup.
  763. initrd= [BOOT] Specify the location of the initial ramdisk
  764. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  765. Format: <irq>
  766. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  767. on
  768. Enable intel iommu driver.
  769. off
  770. Disable intel iommu driver.
  771. igfx_off [Default Off]
  772. By default, gfx is mapped as normal device. If a gfx
  773. device has a dedicated DMAR unit, the DMAR unit is
  774. bypassed by not enabling DMAR with this option. In
  775. this case, gfx device will use physical address for
  776. DMA.
  777. forcedac [x86_64]
  778. With this option iommu will not optimize to look
  779. for io virtual address below 32 bit forcing dual
  780. address cycle on pci bus for cards supporting greater
  781. than 32 bit addressing. The default is to look
  782. for translation below 32 bit and if not available
  783. then look in the higher range.
  784. strict [Default Off]
  785. With this option on every unmap_single operation will
  786. result in a hardware IOTLB flush operation as opposed
  787. to batching them for performance.
  788. inttest= [IA64]
  789. iomem= Disable strict checking of access to MMIO memory
  790. strict regions from userspace.
  791. relaxed
  792. iommu= [x86]
  793. off
  794. force
  795. noforce
  796. biomerge
  797. panic
  798. nopanic
  799. merge
  800. nomerge
  801. forcesac
  802. soft
  803. io7= [HW] IO7 for Marvel based alpha systems
  804. See comment before marvel_specify_io7 in
  805. arch/alpha/kernel/core_marvel.c.
  806. io_delay= [X86] I/O delay method
  807. 0x80
  808. Standard port 0x80 based delay
  809. 0xed
  810. Alternate port 0xed based delay (needed on some systems)
  811. udelay
  812. Simple two microseconds delay
  813. none
  814. No delay
  815. ip= [IP_PNP]
  816. See Documentation/filesystems/nfsroot.txt.
  817. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  818. See comment before ip2_setup() in
  819. drivers/char/ip2/ip2base.c.
  820. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  821. See header of drivers/scsi/ips.c.
  822. irqfixup [HW]
  823. When an interrupt is not handled search all handlers
  824. for it. Intended to get systems with badly broken
  825. firmware running.
  826. irqpoll [HW]
  827. When an interrupt is not handled search all handlers
  828. for it. Also check all handlers each timer
  829. interrupt. Intended to get systems with badly broken
  830. firmware running.
  831. isapnp= [ISAPNP]
  832. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  833. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  834. Format:
  835. <cpu number>,...,<cpu number>
  836. or
  837. <cpu number>-<cpu number>
  838. (must be a positive range in ascending order)
  839. or a mixture
  840. <cpu number>,...,<cpu number>-<cpu number>
  841. This option can be used to specify one or more CPUs
  842. to isolate from the general SMP balancing and scheduling
  843. algorithms. You can move a process onto or off an
  844. "isolated" CPU via the CPU affinity syscalls or cpuset.
  845. <cpu number> begins at 0 and the maximum value is
  846. "number of CPUs in system - 1".
  847. This option is the preferred way to isolate CPUs. The
  848. alternative -- manually setting the CPU mask of all
  849. tasks in the system -- can cause problems and
  850. suboptimal load balancer performance.
  851. iucv= [HW,NET]
  852. js= [HW,JOY] Analog joystick
  853. See Documentation/input/joystick.txt.
  854. keepinitrd [HW,ARM]
  855. kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  856. specifies the amount of memory usable by the kernel
  857. for non-movable allocations. The requested amount is
  858. spread evenly throughout all nodes in the system. The
  859. remaining memory in each node is used for Movable
  860. pages. In the event, a node is too small to have both
  861. kernelcore and Movable pages, kernelcore pages will
  862. take priority and other nodes will have a larger number
  863. of kernelcore pages. The Movable zone is used for the
  864. allocation of pages that may be reclaimed or moved
  865. by the page migration subsystem. This means that
  866. HugeTLB pages may not be allocated from this zone.
  867. Note that allocations like PTEs-from-HighMem still
  868. use the HighMem zone if it exists, and the Normal
  869. zone if it does not.
  870. kgdboc= [HW] kgdb over consoles.
  871. Requires a tty driver that supports console polling.
  872. (only serial suported for now)
  873. Format: <serial_device>[,baud]
  874. kmac= [MIPS] korina ethernet MAC address.
  875. Configure the RouterBoard 532 series on-chip
  876. Ethernet adapter MAC address.
  877. kmemleak= [KNL] Boot-time kmemleak enable/disable
  878. Valid arguments: on, off
  879. Default: on
  880. kstack=N [X86] Print N words from the kernel stack
  881. in oops dumps.
  882. l2cr= [PPC]
  883. l3cr= [PPC]
  884. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  885. disabled it.
  886. lapic_timer_c2_ok [X86,APIC] trust the local apic timer
  887. in C2 power state.
  888. libata.dma= [LIBATA] DMA control
  889. libata.dma=0 Disable all PATA and SATA DMA
  890. libata.dma=1 PATA and SATA Disk DMA only
  891. libata.dma=2 ATAPI (CDROM) DMA only
  892. libata.dma=4 Compact Flash DMA only
  893. Combinations also work, so libata.dma=3 enables DMA
  894. for disks and CDROMs, but not CFs.
  895. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  896. when set.
  897. Format: <int>
  898. libata.force= [LIBATA] Force configurations. The format is comma
  899. separated list of "[ID:]VAL" where ID is
  900. PORT[:DEVICE]. PORT and DEVICE are decimal numbers
  901. matching port, link or device. Basically, it matches
  902. the ATA ID string printed on console by libata. If
  903. the whole ID part is omitted, the last PORT and DEVICE
  904. values are used. If ID hasn't been specified yet, the
  905. configuration applies to all ports, links and devices.
  906. If only DEVICE is omitted, the parameter applies to
  907. the port and all links and devices behind it. DEVICE
  908. number of 0 either selects the first device or the
  909. first fan-out link behind PMP device. It does not
  910. select the host link. DEVICE number of 15 selects the
  911. host link and device attached to it.
  912. The VAL specifies the configuration to force. As long
  913. as there's no ambiguity shortcut notation is allowed.
  914. For example, both 1.5 and 1.5G would work for 1.5Gbps.
  915. The following configurations can be forced.
  916. * Cable type: 40c, 80c, short40c, unk, ign or sata.
  917. Any ID with matching PORT is used.
  918. * SATA link speed limit: 1.5Gbps or 3.0Gbps.
  919. * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
  920. udma[/][16,25,33,44,66,100,133] notation is also
  921. allowed.
  922. * [no]ncq: Turn on or off NCQ.
  923. * nohrst, nosrst, norst: suppress hard, soft
  924. and both resets.
  925. If there are multiple matching configurations changing
  926. the same attribute, the last one is used.
  927. lmb=debug [KNL] Enable lmb debug messages.
  928. load_ramdisk= [RAM] List of ramdisks to load from floppy
  929. See Documentation/blockdev/ramdisk.txt.
  930. lockd.nlm_grace_period=P [NFS] Assign grace period.
  931. Format: <integer>
  932. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  933. Format: <integer>
  934. lockd.nlm_timeout=T [NFS] Assign timeout value.
  935. Format: <integer>
  936. lockd.nlm_udpport=M [NFS] Assign UDP port.
  937. Format: <integer>
  938. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  939. Format: <irq>
  940. loglevel= All Kernel Messages with a loglevel smaller than the
  941. console loglevel will be printed to the console. It can
  942. also be changed with klogd or other programs. The
  943. loglevels are defined as follows:
  944. 0 (KERN_EMERG) system is unusable
  945. 1 (KERN_ALERT) action must be taken immediately
  946. 2 (KERN_CRIT) critical conditions
  947. 3 (KERN_ERR) error conditions
  948. 4 (KERN_WARNING) warning conditions
  949. 5 (KERN_NOTICE) normal but significant condition
  950. 6 (KERN_INFO) informational
  951. 7 (KERN_DEBUG) debug-level messages
  952. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  953. Format: { n | nk | nM }
  954. n must be a power of two. The default size
  955. is set in the kernel config file.
  956. logo.nologo [FB] Disables display of the built-in Linux logo.
  957. This may be used to provide more screen space for
  958. kernel log messages and is useful when debugging
  959. kernel boot problems.
  960. lp=0 [LP] Specify parallel ports to use, e.g,
  961. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  962. lp=reset first parallel port). 'lp=0' disables the
  963. lp=auto printer driver. 'lp=reset' (which can be
  964. specified in addition to the ports) causes
  965. attached printers to be reset. Using
  966. lp=port1,port2,... specifies the parallel ports
  967. to associate lp devices with, starting with
  968. lp0. A port specification may be 'none' to skip
  969. that lp device, or a parport name such as
  970. 'parport0'. Specifying 'lp=auto' instead of a
  971. port specification list means that device IDs
  972. from each port should be examined, to see if
  973. an IEEE 1284-compliant printer is attached; if
  974. so, the driver will manage that printer.
  975. See also header of drivers/char/lp.c.
  976. lpj=n [KNL]
  977. Sets loops_per_jiffy to given constant, thus avoiding
  978. time-consuming boot-time autodetection (up to 250 ms per
  979. CPU). 0 enables autodetection (default). To determine
  980. the correct value for your kernel, boot with normal
  981. autodetection and see what value is printed. Note that
  982. on SMP systems the preset will be applied to all CPUs,
  983. which is likely to cause problems if your CPUs need
  984. significantly divergent settings. An incorrect value
  985. will cause delays in the kernel to be wrong, leading to
  986. unpredictable I/O errors and other breakage. Although
  987. unlikely, in the extreme case this might damage your
  988. hardware.
  989. ltpc= [NET]
  990. Format: <io>,<irq>,<dma>
  991. mac5380= [HW,SCSI] Format:
  992. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  993. machvec= [IA64] Force the use of a particular machine-vector
  994. (machvec) in a generic kernel.
  995. Example: machvec=hpzx1_swiotlb
  996. max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
  997. than or equal to this physical address is ignored.
  998. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  999. should make use of. maxcpus=n : n >= 0 limits the
  1000. kernel to using 'n' processors. n=0 is a special case,
  1001. it is equivalent to "nosmp", which also disables
  1002. the IO APIC.
  1003. max_loop= [LOOP] Maximum number of loopback devices that can
  1004. be mounted
  1005. Format: <1-256>
  1006. max_luns= [SCSI] Maximum number of LUNs to probe.
  1007. Should be between 1 and 2^32-1.
  1008. max_report_luns=
  1009. [SCSI] Maximum number of LUNs received.
  1010. Should be between 1 and 16384.
  1011. mcatest= [IA-64]
  1012. mce [X86-32] Machine Check Exception
  1013. mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
  1014. md= [HW] RAID subsystems devices and level
  1015. See Documentation/md.txt.
  1016. mdacon= [MDA]
  1017. Format: <first>,<last>
  1018. Specifies range of consoles to be captured by the MDA.
  1019. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  1020. Amount of memory to be used when the kernel is not able
  1021. to see the whole system memory or for test.
  1022. [X86-32] Use together with memmap= to avoid physical
  1023. address space collisions. Without memmap= PCI devices
  1024. could be placed at addresses belonging to unused RAM.
  1025. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  1026. memory.
  1027. memchunk=nn[KMG]
  1028. [KNL,SH] Allow user to override the default size for
  1029. per-device physically contiguous DMA buffers.
  1030. memmap=exactmap [KNL,X86] Enable setting of an exact
  1031. E820 memory map, as specified by the user.
  1032. Such memmap=exactmap lines can be constructed based on
  1033. BIOS output or other requirements. See the memmap=nn@ss
  1034. option description.
  1035. memmap=nn[KMG]@ss[KMG]
  1036. [KNL] Force usage of a specific region of memory
  1037. Region of memory to be used, from ss to ss+nn.
  1038. memmap=nn[KMG]#ss[KMG]
  1039. [KNL,ACPI] Mark specific memory as ACPI data.
  1040. Region of memory to be used, from ss to ss+nn.
  1041. memmap=nn[KMG]$ss[KMG]
  1042. [KNL,ACPI] Mark specific memory as reserved.
  1043. Region of memory to be used, from ss to ss+nn.
  1044. Example: Exclude memory from 0x18690000-0x1869ffff
  1045. memmap=64K$0x18690000
  1046. or
  1047. memmap=0x10000$0x18690000
  1048. memory_corruption_check=0/1 [X86]
  1049. Some BIOSes seem to corrupt the first 64k of
  1050. memory when doing things like suspend/resume.
  1051. Setting this option will scan the memory
  1052. looking for corruption. Enabling this will
  1053. both detect corruption and prevent the kernel
  1054. from using the memory being corrupted.
  1055. However, its intended as a diagnostic tool; if
  1056. repeatable BIOS-originated corruption always
  1057. affects the same memory, you can use memmap=
  1058. to prevent the kernel from using that memory.
  1059. memory_corruption_check_size=size [X86]
  1060. By default it checks for corruption in the low
  1061. 64k, making this memory unavailable for normal
  1062. use. Use this parameter to scan for
  1063. corruption in more or less memory.
  1064. memory_corruption_check_period=seconds [X86]
  1065. By default it checks for corruption every 60
  1066. seconds. Use this parameter to check at some
  1067. other rate. 0 disables periodic checking.
  1068. memtest= [KNL,X86] Enable memtest
  1069. Format: <integer>
  1070. default : 0 <disable>
  1071. Specifies the number of memtest passes to be
  1072. performed. Each pass selects another test
  1073. pattern from a given set of patterns. Memtest
  1074. fills the memory with this pattern, validates
  1075. memory contents and reserves bad memory
  1076. regions that are detected.
  1077. meye.*= [HW] Set MotionEye Camera parameters
  1078. See Documentation/video4linux/meye.txt.
  1079. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  1080. Multi-Function General Purpose Timers on AMD Geode
  1081. platforms.
  1082. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  1083. the BIOS has incorrectly applied a workaround. TinyBIOS
  1084. version 0.98 is known to be affected, 0.99 fixes the
  1085. problem by letting the user disable the workaround.
  1086. mga= [HW,DRM]
  1087. min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
  1088. physical address is ignored.
  1089. mminit_loglevel=
  1090. [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
  1091. parameter allows control of the logging verbosity for
  1092. the additional memory initialisation checks. A value
  1093. of 0 disables mminit logging and a level of 4 will
  1094. log everything. Information is printed at KERN_DEBUG
  1095. so loglevel=8 may also need to be specified.
  1096. mousedev.tap_time=
  1097. [MOUSE] Maximum time between finger touching and
  1098. leaving touchpad surface for touch to be considered
  1099. a tap and be reported as a left button click (for
  1100. touchpads working in absolute mode only).
  1101. Format: <msecs>
  1102. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  1103. reporting absolute coordinates, such as tablets
  1104. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  1105. reporting absolute coordinates, such as tablets
  1106. movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  1107. is similar to kernelcore except it specifies the
  1108. amount of memory used for migratable allocations.
  1109. If both kernelcore and movablecore is specified,
  1110. then kernelcore will be at *least* the specified
  1111. value but may be more. If movablecore on its own
  1112. is specified, the administrator must be careful
  1113. that the amount of memory usable for all allocations
  1114. is not too small.
  1115. mpu401= [HW,OSS]
  1116. Format: <io>,<irq>
  1117. MTD_Partition= [MTD]
  1118. Format: <name>,<region-number>,<size>,<offset>
  1119. MTD_Region= [MTD] Format:
  1120. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  1121. mtdparts= [MTD]
  1122. See drivers/mtd/cmdlinepart.c.
  1123. mtdset= [ARM]
  1124. ARM/S3C2412 JIVE boot control
  1125. See arch/arm/mach-s3c2412/mach-jive.c
  1126. mtouchusb.raw_coordinates=
  1127. [HW] Make the MicroTouch USB driver use raw coordinates
  1128. ('y', default) or cooked coordinates ('n')
  1129. mtrr_chunk_size=nn[KMG] [X86]
  1130. used for mtrr cleanup. It is largest continous chunk
  1131. that could hold holes aka. UC entries.
  1132. mtrr_gran_size=nn[KMG] [X86]
  1133. Used for mtrr cleanup. It is granularity of mtrr block.
  1134. Default is 1.
  1135. Large value could prevent small alignment from
  1136. using up MTRRs.
  1137. mtrr_spare_reg_nr=n [X86]
  1138. Format: <integer>
  1139. Range: 0,7 : spare reg number
  1140. Default : 1
  1141. Used for mtrr cleanup. It is spare mtrr entries number.
  1142. Set to 2 or more if your graphical card needs more.
  1143. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  1144. NCR_D700= [HW,SCSI]
  1145. See header of drivers/scsi/NCR_D700.c.
  1146. ncr5380= [HW,SCSI]
  1147. ncr53c400= [HW,SCSI]
  1148. ncr53c400a= [HW,SCSI]
  1149. ncr53c406a= [HW,SCSI]
  1150. ncr53c8xx= [HW,SCSI]
  1151. netdev= [NET] Network devices parameters
  1152. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  1153. Note that mem_start is often overloaded to mean
  1154. something different and driver-specific.
  1155. This usage is only documented in each driver source
  1156. file if at all.
  1157. nf_conntrack.acct=
  1158. [NETFILTER] Enable connection tracking flow accounting
  1159. 0 to disable accounting
  1160. 1 to enable accounting
  1161. Default value depends on CONFIG_NF_CT_ACCT that is
  1162. going to be removed in 2.6.29.
  1163. nfsaddrs= [NFS]
  1164. See Documentation/filesystems/nfsroot.txt.
  1165. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  1166. See Documentation/filesystems/nfsroot.txt.
  1167. nfs.callback_tcpport=
  1168. [NFS] set the TCP port on which the NFSv4 callback
  1169. channel should listen.
  1170. nfs.idmap_cache_timeout=
  1171. [NFS] set the maximum lifetime for idmapper cache
  1172. entries.
  1173. nfs.enable_ino64=
  1174. [NFS] enable 64-bit inode numbers.
  1175. If zero, the NFS client will fake up a 32-bit inode
  1176. number for the readdir() and stat() syscalls instead
  1177. of returning the full 64-bit number.
  1178. The default is to return 64-bit inode numbers.
  1179. nmi_debug= [KNL,AVR32] Specify one or more actions to take
  1180. when a NMI is triggered.
  1181. Format: [state][,regs][,debounce][,die]
  1182. nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
  1183. Format: [panic,][num]
  1184. Valid num: 0,1,2
  1185. 0 - turn nmi_watchdog off
  1186. 1 - use the IO-APIC timer for the NMI watchdog
  1187. 2 - use the local APIC for the NMI watchdog using
  1188. a performance counter. Note: This will use one
  1189. performance counter and the local APIC's performance
  1190. vector.
  1191. When panic is specified, panic when an NMI watchdog
  1192. timeout occurs.
  1193. This is useful when you use a panic=... timeout and
  1194. need the box quickly up again.
  1195. Instead of 1 and 2 it is possible to use the following
  1196. symbolic names: lapic and ioapic
  1197. Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
  1198. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  1199. emulation library even if a 387 maths coprocessor
  1200. is present.
  1201. no_console_suspend
  1202. [HW] Never suspend the console
  1203. Disable suspending of consoles during suspend and
  1204. hibernate operations. Once disabled, debugging
  1205. messages can reach various consoles while the rest
  1206. of the system is being put to sleep (ie, while
  1207. debugging driver suspend/resume hooks). This may
  1208. not work reliably with all consoles, but is known
  1209. to work with serial and VGA consoles.
  1210. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  1211. caches in the slab allocator. Saves per-node memory,
  1212. but will impact performance.
  1213. noalign [KNL,ARM]
  1214. noapic [SMP,APIC] Tells the kernel to not make use of any
  1215. IOAPICs that may be present in the system.
  1216. nobats [PPC] Do not use BATs for mapping kernel lowmem
  1217. on "Classic" PPC cores.
  1218. nocache [ARM]
  1219. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  1220. nodelayacct [KNL] Disable per-task delay accounting
  1221. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  1222. nodsp [SH] Disable hardware DSP at boot time.
  1223. noefi [X86] Disable EFI runtime services support.
  1224. noexec [IA-64]
  1225. noexec [X86]
  1226. On X86-32 available only on PAE configured kernels.
  1227. noexec=on: enable non-executable mappings (default)
  1228. noexec=off: disable non-executable mappings
  1229. noexec32 [X86-64]
  1230. This affects only 32-bit executables.
  1231. noexec32=on: enable non-executable mappings (default)
  1232. read doesn't imply executable mappings
  1233. noexec32=off: disable non-executable mappings
  1234. read implies executable mappings
  1235. nofpu [SH] Disable hardware FPU at boot time.
  1236. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  1237. register save and restore. The kernel will only save
  1238. legacy floating-point registers on task switch.
  1239. noxsave [BUGS=X86] Disables x86 extended register state save
  1240. and restore using xsave. The kernel will fallback to
  1241. enabling legacy floating-point and sse state.
  1242. nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
  1243. wfi(ARM) instruction doesn't work correctly and not to
  1244. use it. This is also useful when using JTAG debugger.
  1245. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  1246. instruction doesn't work correctly and not to
  1247. use it.
  1248. no_file_caps Tells the kernel not to honor file capabilities. The
  1249. only way then for a file to be executed with privilege
  1250. is to be setuid root or executed by root.
  1251. nohalt [IA-64] Tells the kernel not to use the power saving
  1252. function PAL_HALT_LIGHT when idle. This increases
  1253. power-consumption. On the positive side, it reduces
  1254. interrupt wake-up latency, which may improve performance
  1255. in certain environments such as networked servers or
  1256. real-time systems.
  1257. nohz= [KNL] Boottime enable/disable dynamic ticks
  1258. Valid arguments: on, off
  1259. Default: on
  1260. noiotrap [SH] Disables trapped I/O port accesses.
  1261. noirqdebug [X86-32] Disables the code which attempts to detect and
  1262. disable unhandled interrupt sources.
  1263. no_timer_check [X86,APIC] Disables the code which tests for
  1264. broken timer IRQ sources.
  1265. noisapnp [ISAPNP] Disables ISA PnP code.
  1266. noinitrd [RAM] Tells the kernel not to load any configured
  1267. initial RAM disk.
  1268. nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
  1269. remapping.
  1270. nointroute [IA-64]
  1271. nojitter [IA64] Disables jitter checking for ITC timers.
  1272. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  1273. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  1274. noltlbs [PPC] Do not use large page/tlb entries for kernel
  1275. lowmem mapping on PPC40x.
  1276. nomca [IA-64] Disable machine check abort handling
  1277. nomce [X86-32] Machine Check Exception
  1278. nomfgpt [X86-32] Disable Multi-Function General Purpose
  1279. Timer usage (for AMD Geode machines).
  1280. norandmaps Don't use address space randomization. Equivalent to
  1281. echo 0 > /proc/sys/kernel/randomize_va_space
  1282. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  1283. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1284. with UP alternatives
  1285. noresidual [PPC] Don't use residual data on PReP machines.
  1286. noresume [SWSUSP] Disables resume and restores original swap
  1287. space.
  1288. no-scroll [VGA] Disables scrollback.
  1289. This is required for the Braillex ib80-piezo Braille
  1290. reader made by F.H. Papenmeier (Germany).
  1291. nosbagart [IA-64]
  1292. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1293. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1294. and disable the IO APIC. legacy for "maxcpus=0".
  1295. nosoftlockup [KNL] Disable the soft-lockup detector.
  1296. noswapaccount [KNL] Disable accounting of swap in memory resource
  1297. controller. (See Documentation/cgroups/memory.txt)
  1298. nosync [HW,M68K] Disables sync negotiation for all devices.
  1299. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1300. nousb [USB] Disable the USB subsystem
  1301. nowb [ARM]
  1302. nox2apic [X86-64,APIC] Do not enable x2APIC mode.
  1303. nptcg= [IA64] Override max number of concurrent global TLB
  1304. purges which is reported from either PAL_VM_SUMMARY or
  1305. SAL PALO.
  1306. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1307. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1308. one of ['zone', 'node', 'default'] can be specified
  1309. This can be set from sysctl after boot.
  1310. See Documentation/sysctl/vm.txt for details.
  1311. ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
  1312. See Documentation/debugging-via-ohci1394.txt for more
  1313. info.
  1314. olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
  1315. Rather than timing out after 20 ms if an EC
  1316. command is not properly ACKed, override the length
  1317. of the timeout. We have interrupts disabled while
  1318. waiting for the ACK, so if this is set too high
  1319. interrupts *may* be lost!
  1320. opl3= [HW,OSS]
  1321. Format: <io>
  1322. oprofile.timer= [HW]
  1323. Use timer interrupt instead of performance counters
  1324. oprofile.cpu_type= Force an oprofile cpu type
  1325. This might be useful if you have an older oprofile
  1326. userland or if you want common events.
  1327. Format: { archperfmon }
  1328. archperfmon: [X86] Force use of architectural
  1329. perfmon on Intel CPUs instead of the
  1330. CPU specific event set.
  1331. osst= [HW,SCSI] SCSI Tape Driver
  1332. Format: <buffer_size>,<write_threshold>
  1333. See also Documentation/scsi/st.txt.
  1334. panic= [KNL] Kernel behaviour on panic
  1335. Format: <timeout>
  1336. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1337. connected to, default is 0.
  1338. Format: <parport#>
  1339. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1340. 0 for XT, 1 for AT (default is AT).
  1341. Format: <mode>
  1342. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1343. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1344. Use 'auto' to force the driver to use any
  1345. IRQ/DMA settings detected (the default is to
  1346. ignore detected IRQ/DMA settings because of
  1347. possible conflicts). You can specify the base
  1348. address, IRQ, and DMA settings; IRQ and DMA
  1349. should be numbers, or 'auto' (for using detected
  1350. settings on that particular port), or 'nofifo'
  1351. (to avoid using a FIFO even if it is detected).
  1352. Parallel ports are assigned in the order they
  1353. are specified on the command line, starting
  1354. with parport0.
  1355. parport_init_mode= [HW,PPT]
  1356. Configure VIA parallel port to operate in
  1357. a specific mode. This is necessary on Pegasos
  1358. computer where firmware has no options for setting
  1359. up parallel port mode and sets it to spp.
  1360. Currently this function knows 686a and 8231 chips.
  1361. Format: [spp|ps2|epp|ecp|ecpepp]
  1362. pas2= [HW,OSS] Format:
  1363. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1364. pas16= [HW,SCSI]
  1365. See header of drivers/scsi/pas16.c.
  1366. pause_on_oops=
  1367. Halt all CPUs after the first oops has been printed for
  1368. the specified number of seconds. This is to be used if
  1369. your oopses keep scrolling off the screen.
  1370. pcbit= [HW,ISDN]
  1371. pcd. [PARIDE]
  1372. See header of drivers/block/paride/pcd.c.
  1373. See also Documentation/blockdev/paride.txt.
  1374. pci=option[,option...] [PCI] various PCI subsystem options:
  1375. earlydump [X86] dump PCI config space before the kernel
  1376. changes anything
  1377. off [X86] don't probe for the PCI bus
  1378. bios [X86-32] force use of PCI BIOS, don't access
  1379. the hardware directly. Use this if your machine
  1380. has a non-standard PCI host bridge.
  1381. nobios [X86-32] disallow use of PCI BIOS, only direct
  1382. hardware access methods are allowed. Use this
  1383. if you experience crashes upon bootup and you
  1384. suspect they are caused by the BIOS.
  1385. conf1 [X86] Force use of PCI Configuration
  1386. Mechanism 1.
  1387. conf2 [X86] Force use of PCI Configuration
  1388. Mechanism 2.
  1389. noaer [PCIE] If the PCIEAER kernel config parameter is
  1390. enabled, this kernel boot option can be used to
  1391. disable the use of PCIE advanced error reporting.
  1392. nodomains [PCI] Disable support for multiple PCI
  1393. root domains (aka PCI segments, in ACPI-speak).
  1394. nommconf [X86] Disable use of MMCONFIG for PCI
  1395. Configuration
  1396. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1397. enabled, this kernel boot option can be used to
  1398. disable the use of MSI interrupts system-wide.
  1399. noioapicquirk [APIC] Disable all boot interrupt quirks.
  1400. Safety option to keep boot IRQs enabled. This
  1401. should never be necessary.
  1402. ioapicreroute [APIC] Enable rerouting of boot IRQs to the
  1403. primary IO-APIC for bridges that cannot disable
  1404. boot IRQs. This fixes a source of spurious IRQs
  1405. when the system masks IRQs.
  1406. noioapicreroute [APIC] Disable workaround that uses the
  1407. boot IRQ equivalent of an IRQ that connects to
  1408. a chipset where boot IRQs cannot be disabled.
  1409. The opposite of ioapicreroute.
  1410. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1411. routing table. These calls are known to be buggy
  1412. on several machines and they hang the machine
  1413. when used, but on other computers it's the only
  1414. way to get the interrupt routing table. Try
  1415. this option if the kernel is unable to allocate
  1416. IRQs or discover secondary PCI buses on your
  1417. motherboard.
  1418. rom [X86] Assign address space to expansion ROMs.
  1419. Use with caution as certain devices share
  1420. address decoders between ROMs and other
  1421. resources.
  1422. norom [X86] Do not assign address space to
  1423. expansion ROMs that do not already have
  1424. BIOS assigned address ranges.
  1425. irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
  1426. assigned automatically to PCI devices. You can
  1427. make the kernel exclude IRQs of your ISA cards
  1428. this way.
  1429. pirqaddr=0xAAAAA [X86] Specify the physical address
  1430. of the PIRQ table (normally generated
  1431. by the BIOS) if it is outside the
  1432. F0000h-100000h range.
  1433. lastbus=N [X86] Scan all buses thru bus #N. Can be
  1434. useful if the kernel is unable to find your
  1435. secondary buses and you want to tell it
  1436. explicitly which ones they are.
  1437. assign-busses [X86] Always assign all PCI bus
  1438. numbers ourselves, overriding
  1439. whatever the firmware may have done.
  1440. usepirqmask [X86] Honor the possible IRQ mask stored
  1441. in the BIOS $PIR table. This is needed on
  1442. some systems with broken BIOSes, notably
  1443. some HP Pavilion N5400 and Omnibook XE3
  1444. notebooks. This will have no effect if ACPI
  1445. IRQ routing is enabled.
  1446. noacpi [X86] Do not use ACPI for IRQ routing
  1447. or for PCI scanning.
  1448. use_crs [X86] Use _CRS for PCI resource
  1449. allocation.
  1450. routeirq Do IRQ routing for all PCI devices.
  1451. This is normally done in pci_enable_device(),
  1452. so this option is a temporary workaround
  1453. for broken drivers that don't call it.
  1454. skip_isa_align [X86] do not align io start addr, so can
  1455. handle more pci cards
  1456. firmware [ARM] Do not re-enumerate the bus but instead
  1457. just use the configuration from the
  1458. bootloader. This is currently used on
  1459. IXP2000 systems where the bus has to be
  1460. configured a certain way for adjunct CPUs.
  1461. noearly [X86] Don't do any early type 1 scanning.
  1462. This might help on some broken boards which
  1463. machine check when some devices' config space
  1464. is read. But various workarounds are disabled
  1465. and some IOMMU drivers will not work.
  1466. bfsort Sort PCI devices into breadth-first order.
  1467. This sorting is done to get a device
  1468. order compatible with older (<= 2.4) kernels.
  1469. nobfsort Don't sort PCI devices into breadth-first order.
  1470. cbiosize=nn[KMG] The fixed amount of bus space which is
  1471. reserved for the CardBus bridge's IO window.
  1472. The default value is 256 bytes.
  1473. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1474. reserved for the CardBus bridge's memory
  1475. window. The default value is 64 megabytes.
  1476. resource_alignment=
  1477. Format:
  1478. [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
  1479. Specifies alignment and device to reassign
  1480. aligned memory resources.
  1481. If <order of align> is not specified,
  1482. PAGE_SIZE is used as alignment.
  1483. PCI-PCI bridge can be specified, if resource
  1484. windows need to be expanded.
  1485. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
  1486. Management.
  1487. off Disable ASPM.
  1488. force Enable ASPM even on devices that claim not to support it.
  1489. WARNING: Forcing ASPM on may cause system lockups.
  1490. pcmv= [HW,PCMCIA] BadgePAD 4
  1491. pd. [PARIDE]
  1492. See Documentation/blockdev/paride.txt.
  1493. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1494. boot time.
  1495. Format: { 0 | 1 }
  1496. See arch/parisc/kernel/pdc_chassis.c
  1497. pf. [PARIDE]
  1498. See Documentation/blockdev/paride.txt.
  1499. pg. [PARIDE]
  1500. See Documentation/blockdev/paride.txt.
  1501. pirq= [SMP,APIC] Manual mp-table setup
  1502. See Documentation/x86/i386/IO-APIC.txt.
  1503. plip= [PPT,NET] Parallel port network link
  1504. Format: { parport<nr> | timid | 0 }
  1505. See also Documentation/parport.txt.
  1506. pmtmr= [X86] Manual setup of pmtmr I/O Port.
  1507. Override pmtimer IOPort with a hex value.
  1508. e.g. pmtmr=0x508
  1509. pnp.debug [PNP]
  1510. Enable PNP debug messages. This depends on the
  1511. CONFIG_PNP_DEBUG_MESSAGES option.
  1512. pnpacpi= [ACPI]
  1513. { off }
  1514. pnpbios= [ISAPNP]
  1515. { on | off | curr | res | no-curr | no-res }
  1516. pnp_reserve_irq=
  1517. [ISAPNP] Exclude IRQs for the autoconfiguration
  1518. pnp_reserve_dma=
  1519. [ISAPNP] Exclude DMAs for the autoconfiguration
  1520. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1521. Ranges are in pairs (I/O port base and size).
  1522. pnp_reserve_mem=
  1523. [ISAPNP] Exclude memory regions for the
  1524. autoconfiguration.
  1525. Ranges are in pairs (memory base and size).
  1526. ports= [IP_VS_FTP] IPVS ftp helper module
  1527. Default is 21.
  1528. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  1529. may be specified.
  1530. Format: <port>,<port>....
  1531. print-fatal-signals=
  1532. [KNL] debug: print fatal signals
  1533. print-fatal-signals=1: print segfault info to
  1534. the kernel console.
  1535. default: off.
  1536. printk.time= Show timing data prefixed to each printk message line
  1537. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1538. processor.max_cstate= [HW,ACPI]
  1539. Limit processor to maximum C-state
  1540. max_cstate=9 overrides any DMI blacklist limit.
  1541. processor.nocst [HW,ACPI]
  1542. Ignore the _CST method to determine C-states,
  1543. instead using the legacy FADT method
  1544. profile= [KNL] Enable kernel profiling via /proc/profile
  1545. Format: [schedule,]<number>
  1546. Param: "schedule" - profile schedule points.
  1547. Param: <number> - step/bucket size as a power of 2 for
  1548. statistical time based profiling.
  1549. Param: "sleep" - profile D-state sleeping (millisecs).
  1550. Requires CONFIG_SCHEDSTATS
  1551. Param: "kvm" - profile VM exits.
  1552. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1553. before loading.
  1554. See Documentation/blockdev/ramdisk.txt.
  1555. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1556. probe for; one of (bare|imps|exps|lifebook|any).
  1557. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1558. per second.
  1559. psmouse.resetafter= [HW,MOUSE]
  1560. Try to reset the device after so many bad packets
  1561. (0 = never).
  1562. psmouse.resolution=
  1563. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1564. psmouse.smartscroll=
  1565. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1566. 0 = disabled, 1 = enabled (default).
  1567. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1568. Format:
  1569. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1570. pt. [PARIDE]
  1571. See Documentation/blockdev/paride.txt.
  1572. pty.legacy_count=
  1573. [KNL] Number of legacy pty's. Overwrites compiled-in
  1574. default number.
  1575. quiet [KNL] Disable most log messages
  1576. r128= [HW,DRM]
  1577. raid= [HW,RAID]
  1578. See Documentation/md.txt.
  1579. ramdisk_blocksize= [RAM]
  1580. See Documentation/blockdev/ramdisk.txt.
  1581. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1582. See Documentation/blockdev/ramdisk.txt.
  1583. rcupdate.blimit= [KNL,BOOT]
  1584. Set maximum number of finished RCU callbacks to process
  1585. in one batch.
  1586. rcupdate.qhimark= [KNL,BOOT]
  1587. Set threshold of queued
  1588. RCU callbacks over which batch limiting is disabled.
  1589. rcupdate.qlowmark= [KNL,BOOT]
  1590. Set threshold of queued RCU callbacks below which
  1591. batch limiting is re-enabled.
  1592. rdinit= [KNL]
  1593. Format: <full_path>
  1594. Run specified binary instead of /init from the ramdisk,
  1595. used for early userspace startup. See initrd.
  1596. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1597. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1598. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1599. relax_domain_level=
  1600. [KNL, SMP] Set scheduler's default relax_domain_level.
  1601. See Documentation/cgroups/cpusets.txt.
  1602. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1603. reservetop= [X86-32]
  1604. Format: nn[KMG]
  1605. Reserves a hole at the top of the kernel virtual
  1606. address space.
  1607. reset_devices [KNL] Force drivers to reset the underlying device
  1608. during initialization.
  1609. resume= [SWSUSP]
  1610. Specify the partition device for software suspend
  1611. resume_offset= [SWSUSP]
  1612. Specify the offset from the beginning of the partition
  1613. given by "resume=" at which the swap header is located,
  1614. in <PAGE_SIZE> units (needed only for swap files).
  1615. See Documentation/power/swsusp-and-swap-files.txt
  1616. retain_initrd [RAM] Keep initrd memory after extraction
  1617. rhash_entries= [KNL,NET]
  1618. Set number of hash buckets for route cache
  1619. riscom8= [HW,SERIAL]
  1620. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1621. ro [KNL] Mount root device read-only on boot
  1622. root= [KNL] Root filesystem
  1623. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1624. mount the root filesystem
  1625. rootflags= [KNL] Set root filesystem mount option string
  1626. rootfstype= [KNL] Set root filesystem type
  1627. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1628. Useful for devices that are detected asynchronously
  1629. (e.g. USB and MMC devices).
  1630. root_plug.vendor_id=
  1631. [ROOTPLUG] Override the default vendor ID
  1632. root_plug.product_id=
  1633. [ROOTPLUG] Override the default product ID
  1634. root_plug.debug=
  1635. [ROOTPLUG] Enable debugging output
  1636. rw [KNL] Mount root device read-write on boot
  1637. S [KNL] Run init in single mode
  1638. sa1100ir [NET]
  1639. See drivers/net/irda/sa1100_ir.c.
  1640. sbni= [NET] Granch SBNI12 leased line adapter
  1641. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1642. Format: <io>[,<timeout>[,<isapnp>]]
  1643. scsi_debug_*= [SCSI]
  1644. See drivers/scsi/scsi_debug.c.
  1645. scsi_default_dev_flags=
  1646. [SCSI] SCSI default device flags
  1647. Format: <integer>
  1648. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1649. Format: <vendor>:<model>:<flags>
  1650. (flags are integer value)
  1651. scsi_logging_level= [SCSI] a bit mask of logging levels
  1652. See drivers/scsi/scsi_logging.h for bits. Also
  1653. settable via sysctl at dev.scsi.logging_level
  1654. (/proc/sys/dev/scsi/logging_level).
  1655. There is also a nice 'scsi_logging_level' script in the
  1656. S390-tools package, available for download at
  1657. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1658. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1659. discovered. async scans them in kernel threads,
  1660. allowing boot to proceed. none ignores them, expecting
  1661. user space to do the scan.
  1662. security= [SECURITY] Choose a security module to enable at boot.
  1663. If this boot parameter is not specified, only the first
  1664. security module asking for security registration will be
  1665. loaded. An invalid security module name will be treated
  1666. as if no module has been chosen.
  1667. selinux= [SELINUX] Disable or enable SELinux at boot time.
  1668. Format: { "0" | "1" }
  1669. See security/selinux/Kconfig help text.
  1670. 0 -- disable.
  1671. 1 -- enable.
  1672. Default value is set via kernel config option.
  1673. If enabled at boot time, /selinux/disable can be used
  1674. later to disable prior to initial policy load.
  1675. serialnumber [BUGS=X86-32]
  1676. shapers= [NET]
  1677. Maximal number of shapers.
  1678. show_msr= [x86] show boot-time MSR settings
  1679. Format: { <integer> }
  1680. Show boot-time (BIOS-initialized) MSR settings.
  1681. The parameter means the number of CPUs to show,
  1682. for example 1 means boot CPU only.
  1683. sim710= [SCSI,HW]
  1684. See header of drivers/scsi/sim710.c.
  1685. simeth= [IA-64]
  1686. simscsi=
  1687. slram= [HW,MTD]
  1688. slub_debug[=options[,slabs]] [MM, SLUB]
  1689. Enabling slub_debug allows one to determine the
  1690. culprit if slab objects become corrupted. Enabling
  1691. slub_debug can create guard zones around objects and
  1692. may poison objects when not in use. Also tracks the
  1693. last alloc / free. For more information see
  1694. Documentation/vm/slub.txt.
  1695. slub_max_order= [MM, SLUB]
  1696. Determines the maximum allowed order for slabs.
  1697. A high setting may cause OOMs due to memory
  1698. fragmentation. For more information see
  1699. Documentation/vm/slub.txt.
  1700. slub_min_objects= [MM, SLUB]
  1701. The minimum number of objects per slab. SLUB will
  1702. increase the slab order up to slub_max_order to
  1703. generate a sufficiently large slab able to contain
  1704. the number of objects indicated. The higher the number
  1705. of objects the smaller the overhead of tracking slabs
  1706. and the less frequently locks need to be acquired.
  1707. For more information see Documentation/vm/slub.txt.
  1708. slub_min_order= [MM, SLUB]
  1709. Determines the mininum page order for slabs. Must be
  1710. lower than slub_max_order.
  1711. For more information see Documentation/vm/slub.txt.
  1712. slub_nomerge [MM, SLUB]
  1713. Disable merging of slabs with similar size. May be
  1714. necessary if there is some reason to distinguish
  1715. allocs to different slabs. Debug options disable
  1716. merging on their own.
  1717. For more information see Documentation/vm/slub.txt.
  1718. smart2= [HW]
  1719. Format: <io1>[,<io2>[,...,<io8>]]
  1720. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1721. attempt to substitute SMP alternatives once at boot.
  1722. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1723. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1724. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1725. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1726. smsc-ircc2.ircc_irq= [HW] IRQ line
  1727. smsc-ircc2.ircc_dma= [HW] DMA channel
  1728. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1729. 0: Toshiba Satellite 1800 (GP data pin select)
  1730. 1: Fast pin select (default)
  1731. 2: ATC IRMode
  1732. snd-ad1816a= [HW,ALSA]
  1733. snd-ad1848= [HW,ALSA]
  1734. snd-ali5451= [HW,ALSA]
  1735. snd-als100= [HW,ALSA]
  1736. snd-als4000= [HW,ALSA]
  1737. snd-azt2320= [HW,ALSA]
  1738. snd-cmi8330= [HW,ALSA]
  1739. snd-cmipci= [HW,ALSA]
  1740. snd-cs4231= [HW,ALSA]
  1741. snd-cs4232= [HW,ALSA]
  1742. snd-cs4236= [HW,ALSA]
  1743. snd-cs4281= [HW,ALSA]
  1744. snd-cs46xx= [HW,ALSA]
  1745. snd-dt019x= [HW,ALSA]
  1746. snd-dummy= [HW,ALSA]
  1747. snd-emu10k1= [HW,ALSA]
  1748. snd-ens1370= [HW,ALSA]
  1749. snd-ens1371= [HW,ALSA]
  1750. snd-es968= [HW,ALSA]
  1751. snd-es1688= [HW,ALSA]
  1752. snd-es18xx= [HW,ALSA]
  1753. snd-es1938= [HW,ALSA]
  1754. snd-es1968= [HW,ALSA]
  1755. snd-fm801= [HW,ALSA]
  1756. snd-gusclassic= [HW,ALSA]
  1757. snd-gusextreme= [HW,ALSA]
  1758. snd-gusmax= [HW,ALSA]
  1759. snd-hdsp= [HW,ALSA]
  1760. snd-ice1712= [HW,ALSA]
  1761. snd-intel8x0= [HW,ALSA]
  1762. snd-interwave= [HW,ALSA]
  1763. snd-interwave-stb=
  1764. [HW,ALSA]
  1765. snd-korg1212= [HW,ALSA]
  1766. snd-maestro3= [HW,ALSA]
  1767. snd-mpu401= [HW,ALSA]
  1768. snd-mtpav= [HW,ALSA]
  1769. snd-nm256= [HW,ALSA]
  1770. snd-opl3sa2= [HW,ALSA]
  1771. snd-opti92x-ad1848=
  1772. [HW,ALSA]
  1773. snd-opti92x-cs4231=
  1774. [HW,ALSA]
  1775. snd-opti93x= [HW,ALSA]
  1776. snd-pmac= [HW,ALSA]
  1777. snd-rme32= [HW,ALSA]
  1778. snd-rme96= [HW,ALSA]
  1779. snd-rme9652= [HW,ALSA]
  1780. snd-sb8= [HW,ALSA]
  1781. snd-sb16= [HW,ALSA]
  1782. snd-sbawe= [HW,ALSA]
  1783. snd-serial= [HW,ALSA]
  1784. snd-sgalaxy= [HW,ALSA]
  1785. snd-sonicvibes= [HW,ALSA]
  1786. snd-sun-amd7930=
  1787. [HW,ALSA]
  1788. snd-sun-cs4231= [HW,ALSA]
  1789. snd-trident= [HW,ALSA]
  1790. snd-usb-audio= [HW,ALSA,USB]
  1791. snd-via82xx= [HW,ALSA]
  1792. snd-virmidi= [HW,ALSA]
  1793. snd-wavefront= [HW,ALSA]
  1794. snd-ymfpci= [HW,ALSA]
  1795. softlockup_panic=
  1796. [KNL] Should the soft-lockup detector generate panics.
  1797. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1798. See Documentation/sonypi.txt
  1799. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1800. See Documentation/serial/specialix.txt.
  1801. spia_io_base= [HW,MTD]
  1802. spia_fio_base=
  1803. spia_pedr=
  1804. spia_peddr=
  1805. sscape= [HW,OSS]
  1806. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1807. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1808. See Documentation/scsi/st.txt.
  1809. stacktrace [FTRACE]
  1810. Enabled the stack tracer on boot up.
  1811. sti= [PARISC,HW]
  1812. Format: <num>
  1813. Set the STI (builtin display/keyboard on the HP-PARISC
  1814. machines) console (graphic card) which should be used
  1815. as the initial boot-console.
  1816. See also comment in drivers/video/console/sticore.c.
  1817. sti_font= [HW]
  1818. See comment in drivers/video/console/sticore.c.
  1819. stifb= [HW]
  1820. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1821. sunrpc.pool_mode=
  1822. [NFS]
  1823. Control how the NFS server code allocates CPUs to
  1824. service thread pools. Depending on how many NICs
  1825. you have and where their interrupts are bound, this
  1826. option will affect which CPUs will do NFS serving.
  1827. Note: this parameter cannot be changed while the
  1828. NFS server is running.
  1829. auto the server chooses an appropriate mode
  1830. automatically using heuristics
  1831. global a single global pool contains all CPUs
  1832. percpu one pool for each CPU
  1833. pernode one pool for each NUMA node (equivalent
  1834. to global on non-NUMA machines)
  1835. swiotlb= [IA-64] Number of I/O TLB slabs
  1836. switches= [HW,M68k]
  1837. sym53c416= [HW,SCSI]
  1838. See header of drivers/scsi/sym53c416.c.
  1839. sysrq_always_enabled
  1840. [KNL]
  1841. Ignore sysrq setting - this boot parameter will
  1842. neutralize any effect of /proc/sys/kernel/sysrq.
  1843. Useful for debugging.
  1844. t128= [HW,SCSI]
  1845. See header of drivers/scsi/t128.c.
  1846. tdfx= [HW,DRM]
  1847. test_suspend= [SUSPEND]
  1848. Specify "mem" (for Suspend-to-RAM) or "standby" (for
  1849. standby suspend) as the system sleep state to briefly
  1850. enter during system startup. The system is woken from
  1851. this state using a wakeup-capable RTC alarm.
  1852. thash_entries= [KNL,NET]
  1853. Set number of hash buckets for TCP connection
  1854. thermal.act= [HW,ACPI]
  1855. -1: disable all active trip points in all thermal zones
  1856. <degrees C>: override all lowest active trip points
  1857. thermal.crt= [HW,ACPI]
  1858. -1: disable all critical trip points in all thermal zones
  1859. <degrees C>: override all critical trip points
  1860. thermal.nocrt= [HW,ACPI]
  1861. Set to disable actions on ACPI thermal zone
  1862. critical and hot trip points.
  1863. thermal.off= [HW,ACPI]
  1864. 1: disable ACPI thermal control
  1865. thermal.psv= [HW,ACPI]
  1866. -1: disable all passive trip points
  1867. <degrees C>: override all passive trip points to this
  1868. value
  1869. thermal.tzp= [HW,ACPI]
  1870. Specify global default ACPI thermal zone polling rate
  1871. <deci-seconds>: poll all this frequency
  1872. 0: no polling (default)
  1873. tmscsim= [HW,SCSI]
  1874. See comment before function dc390_setup() in
  1875. drivers/scsi/tmscsim.c.
  1876. topology= [S390]
  1877. Format: {off | on}
  1878. Specify if the kernel should make use of the cpu
  1879. topology informations if the hardware supports these.
  1880. The scheduler will make use of these informations and
  1881. e.g. base its process migration decisions on it.
  1882. Default is off.
  1883. tp720= [HW,PS2]
  1884. trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
  1885. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1886. Format:
  1887. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1888. tsc= Disable clocksource-must-verify flag for TSC.
  1889. Format: <string>
  1890. [x86] reliable: mark tsc clocksource as reliable, this
  1891. disables clocksource verification at runtime.
  1892. Used to enable high-resolution timer mode on older
  1893. hardware, and in virtualized environment.
  1894. turbografx.map[2|3]= [HW,JOY]
  1895. TurboGraFX parallel port interface
  1896. Format:
  1897. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1898. See also Documentation/input/joystick-parport.txt
  1899. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1900. See header of drivers/scsi/u14-34f.c.
  1901. uart401= [HW,OSS]
  1902. Format: <io>,<irq>
  1903. uart6850= [HW,OSS]
  1904. Format: <io>,<irq>
  1905. uhci-hcd.ignore_oc=
  1906. [USB] Ignore overcurrent events (default N).
  1907. Some badly-designed motherboards generate lots of
  1908. bogus events, for ports that aren't wired to
  1909. anything. Set this parameter to avoid log spamming.
  1910. Note that genuine overcurrent events won't be
  1911. reported either.
  1912. unknown_nmi_panic
  1913. [X86]
  1914. Set unknown_nmi_panic=1 early on boot.
  1915. usbcore.autosuspend=
  1916. [USB] The autosuspend time delay (in seconds) used
  1917. for newly-detected USB devices (default 2). This
  1918. is the time required before an idle device will be
  1919. autosuspended. Devices for which the delay is set
  1920. to a negative value won't be autosuspended at all.
  1921. usbcore.usbfs_snoop=
  1922. [USB] Set to log all usbfs traffic (default 0 = off).
  1923. usbcore.blinkenlights=
  1924. [USB] Set to cycle leds on hubs (default 0 = off).
  1925. usbcore.old_scheme_first=
  1926. [USB] Start with the old device initialization
  1927. scheme (default 0 = off).
  1928. usbcore.use_both_schemes=
  1929. [USB] Try the other device initialization scheme
  1930. if the first one fails (default 1 = enabled).
  1931. usbcore.initial_descriptor_timeout=
  1932. [USB] Specifies timeout for the initial 64-byte
  1933. USB_REQ_GET_DESCRIPTOR request in milliseconds
  1934. (default 5000 = 5.0 seconds).
  1935. usbhid.mousepoll=
  1936. [USBHID] The interval which mice are to be polled at.
  1937. usb-storage.delay_use=
  1938. [UMS] The delay in seconds before a new device is
  1939. scanned for Logical Units (default 5).
  1940. usb-storage.quirks=
  1941. [UMS] A list of quirks entries to supplement or
  1942. override the built-in unusual_devs list. List
  1943. entries are separated by commas. Each entry has
  1944. the form VID:PID:Flags where VID and PID are Vendor
  1945. and Product ID values (4-digit hex numbers) and
  1946. Flags is a set of characters, each corresponding
  1947. to a common usb-storage quirk flag as follows:
  1948. a = SANE_SENSE (collect more than 18 bytes
  1949. of sense data);
  1950. c = FIX_CAPACITY (decrease the reported
  1951. device capacity by one sector);
  1952. h = CAPACITY_HEURISTICS (decrease the
  1953. reported device capacity by one
  1954. sector if the number is odd);
  1955. i = IGNORE_DEVICE (don't bind to this
  1956. device);
  1957. l = NOT_LOCKABLE (don't try to lock and
  1958. unlock ejectable media);
  1959. m = MAX_SECTORS_64 (don't transfer more
  1960. than 64 sectors = 32 KB at a time);
  1961. o = CAPACITY_OK (accept the capacity
  1962. reported by the device);
  1963. r = IGNORE_RESIDUE (the device reports
  1964. bogus residue values);
  1965. s = SINGLE_LUN (the device has only one
  1966. Logical Unit);
  1967. w = NO_WP_DETECT (don't test whether the
  1968. medium is write-protected).
  1969. Example: quirks=0419:aaf5:rl,0421:0433:rc
  1970. vdso= [X86,SH]
  1971. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  1972. vdso=1: enable VDSO (default)
  1973. vdso=0: disable VDSO mapping
  1974. vdso32= [X86]
  1975. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  1976. vdso32=1: enable 32-bit VDSO (default)
  1977. vdso32=0: disable 32-bit VDSO mapping
  1978. vector= [IA-64,SMP]
  1979. vector=percpu: enable percpu vector domain
  1980. video= [FB] Frame buffer configuration
  1981. See Documentation/fb/modedb.txt.
  1982. vga= [BOOT,X86-32] Select a particular video mode
  1983. See Documentation/x86/boot.txt and
  1984. Documentation/svga.txt.
  1985. Use vga=ask for menu.
  1986. This is actually a boot loader parameter; the value is
  1987. passed to the kernel using a special protocol.
  1988. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1989. size of <nn>. This can be used to increase the
  1990. minimum size (128MB on x86). It can also be used to
  1991. decrease the size and leave more room for directly
  1992. mapped kernel RAM.
  1993. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1994. Format: <command>
  1995. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1996. Format: <command>
  1997. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1998. Format: <command>
  1999. vt.default_blu= [VT]
  2000. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  2001. Change the default blue palette of the console.
  2002. This is a 16-member array composed of values
  2003. ranging from 0-255.
  2004. vt.default_grn= [VT]
  2005. Format: <green0>,<green1>,<green2>,...,<green15>
  2006. Change the default green palette of the console.
  2007. This is a 16-member array composed of values
  2008. ranging from 0-255.
  2009. vt.default_red= [VT]
  2010. Format: <red0>,<red1>,<red2>,...,<red15>
  2011. Change the default red palette of the console.
  2012. This is a 16-member array composed of values
  2013. ranging from 0-255.
  2014. vt.default_utf8=
  2015. [VT]
  2016. Format=<0|1>
  2017. Set system-wide default UTF-8 mode for all tty's.
  2018. Default is 1, i.e. UTF-8 mode is enabled for all
  2019. newly opened terminals.
  2020. waveartist= [HW,OSS]
  2021. Format: <io>,<irq>,<dma>,<dma2>
  2022. wd33c93= [HW,SCSI]
  2023. See header of drivers/scsi/wd33c93.c.
  2024. wd7000= [HW,SCSI]
  2025. See header of drivers/scsi/wd7000.c.
  2026. wdt= [WDT] Watchdog
  2027. See Documentation/watchdog/wdt.txt.
  2028. x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
  2029. default x2apic cluster mode on platforms
  2030. supporting x2apic.
  2031. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  2032. xd_geo= See header of drivers/block/xd.c.
  2033. xirc2ps_cs= [NET,PCMCIA]
  2034. Format:
  2035. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  2036. ______________________________________________________________________
  2037. TODO:
  2038. Add documentation for ALSA options.
  2039. Add more DRM drivers.