kernel-parameters.txt 93 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878879880881882883884885886887888889890891892893894895896897898899900901902903904905906907908909910911912913914915916917918919920921922923924925926927928929930931932933934935936937938939940941942943944945946947948949950951952953954955956957958959960961962963964965966967968969970971972973974975976977978979980981982983984985986987988989990991992993994995996997998999100010011002100310041005100610071008100910101011101210131014101510161017101810191020102110221023102410251026102710281029103010311032103310341035103610371038103910401041104210431044104510461047104810491050105110521053105410551056105710581059106010611062106310641065106610671068106910701071107210731074107510761077107810791080108110821083108410851086108710881089109010911092109310941095109610971098109911001101110211031104110511061107110811091110111111121113111411151116111711181119112011211122112311241125112611271128112911301131113211331134113511361137113811391140114111421143114411451146114711481149115011511152115311541155115611571158115911601161116211631164116511661167116811691170117111721173117411751176117711781179118011811182118311841185118611871188118911901191119211931194119511961197119811991200120112021203120412051206120712081209121012111212121312141215121612171218121912201221122212231224122512261227122812291230123112321233123412351236123712381239124012411242124312441245124612471248124912501251125212531254125512561257125812591260126112621263126412651266126712681269127012711272127312741275127612771278127912801281128212831284128512861287128812891290129112921293129412951296129712981299130013011302130313041305130613071308130913101311131213131314131513161317131813191320132113221323132413251326132713281329133013311332133313341335133613371338133913401341134213431344134513461347134813491350135113521353135413551356135713581359136013611362136313641365136613671368136913701371137213731374137513761377137813791380138113821383138413851386138713881389139013911392139313941395139613971398139914001401140214031404140514061407140814091410141114121413141414151416141714181419142014211422142314241425142614271428142914301431143214331434143514361437143814391440144114421443144414451446144714481449145014511452145314541455145614571458145914601461146214631464146514661467146814691470147114721473147414751476147714781479148014811482148314841485148614871488148914901491149214931494149514961497149814991500150115021503150415051506150715081509151015111512151315141515151615171518151915201521152215231524152515261527152815291530153115321533153415351536153715381539154015411542154315441545154615471548154915501551155215531554155515561557155815591560156115621563156415651566156715681569157015711572157315741575157615771578157915801581158215831584158515861587158815891590159115921593159415951596159715981599160016011602160316041605160616071608160916101611161216131614161516161617161816191620162116221623162416251626162716281629163016311632163316341635163616371638163916401641164216431644164516461647164816491650165116521653165416551656165716581659166016611662166316641665166616671668166916701671167216731674167516761677167816791680168116821683168416851686168716881689169016911692169316941695169616971698169917001701170217031704170517061707170817091710171117121713171417151716171717181719172017211722172317241725172617271728172917301731173217331734173517361737173817391740174117421743174417451746174717481749175017511752175317541755175617571758175917601761176217631764176517661767176817691770177117721773177417751776177717781779178017811782178317841785178617871788178917901791179217931794179517961797179817991800180118021803180418051806180718081809181018111812181318141815181618171818181918201821182218231824182518261827182818291830183118321833183418351836183718381839184018411842184318441845184618471848184918501851185218531854185518561857185818591860186118621863186418651866186718681869187018711872187318741875187618771878187918801881188218831884188518861887188818891890189118921893189418951896189718981899190019011902190319041905190619071908190919101911191219131914191519161917191819191920192119221923192419251926192719281929193019311932193319341935193619371938193919401941194219431944194519461947194819491950195119521953195419551956195719581959196019611962196319641965196619671968196919701971197219731974197519761977197819791980198119821983198419851986198719881989199019911992199319941995199619971998199920002001200220032004200520062007200820092010201120122013201420152016201720182019202020212022202320242025202620272028202920302031203220332034203520362037203820392040204120422043204420452046204720482049205020512052205320542055205620572058205920602061206220632064206520662067206820692070207120722073207420752076207720782079208020812082208320842085208620872088208920902091209220932094209520962097209820992100210121022103210421052106210721082109211021112112211321142115211621172118211921202121212221232124212521262127212821292130213121322133213421352136213721382139214021412142214321442145214621472148214921502151215221532154215521562157215821592160216121622163216421652166216721682169217021712172217321742175217621772178217921802181218221832184218521862187218821892190219121922193219421952196219721982199220022012202220322042205220622072208220922102211221222132214221522162217221822192220222122222223222422252226222722282229223022312232223322342235223622372238223922402241224222432244224522462247224822492250225122522253225422552256225722582259226022612262226322642265226622672268226922702271227222732274227522762277227822792280228122822283228422852286228722882289229022912292229322942295229622972298229923002301230223032304230523062307230823092310231123122313231423152316231723182319232023212322232323242325232623272328232923302331233223332334233523362337233823392340234123422343234423452346234723482349235023512352235323542355235623572358235923602361236223632364236523662367236823692370237123722373237423752376237723782379238023812382238323842385238623872388238923902391239223932394239523962397239823992400240124022403240424052406240724082409241024112412241324142415241624172418241924202421242224232424242524262427242824292430243124322433243424352436243724382439244024412442244324442445244624472448244924502451245224532454245524562457245824592460246124622463246424652466246724682469247024712472247324742475247624772478247924802481248224832484248524862487248824892490249124922493249424952496249724982499250025012502250325042505250625072508250925102511251225132514251525162517251825192520252125222523252425252526252725282529253025312532253325342535253625372538253925402541254225432544254525462547254825492550255125522553255425552556255725582559256025612562256325642565256625672568256925702571257225732574257525762577257825792580258125822583258425852586258725882589259025912592259325942595259625972598259926002601260226032604260526062607260826092610261126122613261426152616261726182619262026212622262326242625262626272628262926302631263226332634263526362637263826392640264126422643264426452646264726482649265026512652265326542655265626572658265926602661266226632664266526662667266826692670267126722673267426752676267726782679268026812682268326842685268626872688268926902691269226932694269526962697269826992700270127022703270427052706270727082709271027112712271327142715271627172718271927202721272227232724272527262727272827292730273127322733273427352736273727382739274027412742274327442745274627472748274927502751275227532754275527562757275827592760276127622763276427652766276727682769277027712772277327742775277627772778277927802781278227832784278527862787278827892790279127922793279427952796279727982799280028012802280328042805280628072808280928102811281228132814281528162817281828192820282128222823282428252826282728282829283028312832283328342835283628372838283928402841284228432844284528462847284828492850285128522853285428552856285728582859286028612862286328642865286628672868286928702871287228732874287528762877287828792880288128822883288428852886288728882889289028912892289328942895289628972898
  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. GCOV GCOV profiling is enabled.
  42. HW Appropriate hardware is enabled.
  43. IA-64 IA-64 architecture is enabled.
  44. IMA Integrity measurement architecture is enabled.
  45. IOSCHED More than one I/O scheduler is enabled.
  46. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  47. IPV6 IPv6 support is enabled.
  48. ISAPNP ISA PnP code is enabled.
  49. ISDN Appropriate ISDN support is enabled.
  50. JOY Appropriate joystick support is enabled.
  51. KGDB Kernel debugger support is enabled.
  52. KVM Kernel Virtual Machine support is enabled.
  53. LIBATA Libata driver is enabled
  54. LP Printer support is enabled.
  55. LOOP Loopback device support is enabled.
  56. M68k M68k architecture is enabled.
  57. These options have more detailed description inside of
  58. Documentation/m68k/kernel-options.txt.
  59. MCA MCA bus support is enabled.
  60. MDA MDA console support is enabled.
  61. MOUSE Appropriate mouse support is enabled.
  62. MSI Message Signaled Interrupts (PCI).
  63. MTD MTD (Memory Technology Device) support is enabled.
  64. NET Appropriate network support is enabled.
  65. NUMA NUMA support is enabled.
  66. GENERIC_TIME The generic timeofday code is enabled.
  67. NFS Appropriate NFS support is enabled.
  68. OSS OSS sound support is enabled.
  69. PV_OPS A paravirtualized kernel is enabled.
  70. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  71. PARISC The PA-RISC architecture is enabled.
  72. PCI PCI bus support is enabled.
  73. PCIE PCI Express support is enabled.
  74. PCMCIA The PCMCIA subsystem is enabled.
  75. PNP Plug & Play support is enabled.
  76. PPC PowerPC architecture is enabled.
  77. PPT Parallel port support is enabled.
  78. PS2 Appropriate PS/2 support is enabled.
  79. RAM RAM disk support is enabled.
  80. S390 S390 architecture is enabled.
  81. SCSI Appropriate SCSI support is enabled.
  82. A lot of drivers has their options described inside of
  83. Documentation/scsi/.
  84. SECURITY Different security models are enabled.
  85. SELINUX SELinux support is enabled.
  86. APPARMOR AppArmor support is enabled.
  87. SERIAL Serial support is enabled.
  88. SH SuperH architecture is enabled.
  89. SMP The kernel is an SMP kernel.
  90. SPARC Sparc architecture is enabled.
  91. SWSUSP Software suspend (hibernation) is enabled.
  92. SUSPEND System suspend states are enabled.
  93. FTRACE Function tracing enabled.
  94. TPM TPM drivers are enabled.
  95. TS Appropriate touchscreen support is enabled.
  96. UMS USB Mass Storage support is enabled.
  97. USB USB support is enabled.
  98. USBHID USB Human Interface Device support is enabled.
  99. V4L Video For Linux support is enabled.
  100. VGA The VGA console has been enabled.
  101. VT Virtual terminal support is enabled.
  102. WDT Watchdog support is enabled.
  103. XT IBM PC/XT MFM hard disk support is enabled.
  104. X86-32 X86-32, aka i386 architecture is enabled.
  105. X86-64 X86-64 architecture is enabled.
  106. More X86-64 boot options can be found in
  107. Documentation/x86/x86_64/boot-options.txt .
  108. X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
  109. In addition, the following text indicates that the option:
  110. BUGS= Relates to possible processor bugs on the said processor.
  111. KNL Is a kernel start-up parameter.
  112. BOOT Is a boot loader parameter.
  113. Parameters denoted with BOOT are actually interpreted by the boot
  114. loader, and have no meaning to the kernel directly.
  115. Do not modify the syntax of boot loader parameters without extreme
  116. need or coordination with <Documentation/x86/boot.txt>.
  117. There are also arch-specific kernel-parameters not documented here.
  118. See for example <Documentation/x86/x86_64/boot-options.txt>.
  119. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  120. a trailing = on the name of any parameter states that that parameter will
  121. be entered as an environment variable, whereas its absence indicates that
  122. it will appear as a kernel argument readable via /proc/cmdline by programs
  123. running once the system is up.
  124. The number of kernel parameters is not limited, but the length of the
  125. complete command line (parameters including spaces etc.) is limited to
  126. a fixed number of characters. This limit depends on the architecture
  127. and is between 256 and 4096 characters. It is defined in the file
  128. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  129. acpi= [HW,ACPI,X86]
  130. Advanced Configuration and Power Interface
  131. Format: { force | off | strict | noirq | rsdt }
  132. force -- enable ACPI if default was off
  133. off -- disable ACPI if default was on
  134. noirq -- do not use ACPI for IRQ routing
  135. strict -- Be less tolerant of platforms that are not
  136. strictly ACPI specification compliant.
  137. rsdt -- prefer RSDT over (default) XSDT
  138. copy_dsdt -- copy DSDT to memory
  139. See also Documentation/power/pm.txt, pci=noacpi
  140. acpi_apic_instance= [ACPI, IOAPIC]
  141. Format: <int>
  142. 2: use 2nd APIC table, if available
  143. 1,0: use 1st APIC table
  144. default: 0
  145. acpi_backlight= [HW,ACPI]
  146. acpi_backlight=vendor
  147. acpi_backlight=video
  148. If set to vendor, prefer vendor specific driver
  149. (e.g. thinkpad_acpi, sony_acpi, etc.) instead
  150. of the ACPI video.ko driver.
  151. acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
  152. acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
  153. Format: <int>
  154. CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
  155. debug output. Bits in debug_layer correspond to a
  156. _COMPONENT in an ACPI source file, e.g.,
  157. #define _COMPONENT ACPI_PCI_COMPONENT
  158. Bits in debug_level correspond to a level in
  159. ACPI_DEBUG_PRINT statements, e.g.,
  160. ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
  161. The debug_level mask defaults to "info". See
  162. Documentation/acpi/debug.txt for more information about
  163. debug layers and levels.
  164. Enable processor driver info messages:
  165. acpi.debug_layer=0x20000000
  166. Enable PCI/PCI interrupt routing info messages:
  167. acpi.debug_layer=0x400000
  168. Enable AML "Debug" output, i.e., stores to the Debug
  169. object while interpreting AML:
  170. acpi.debug_layer=0xffffffff acpi.debug_level=0x2
  171. Enable all messages related to ACPI hardware:
  172. acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
  173. Some values produce so much output that the system is
  174. unusable. The "log_buf_len" parameter may be useful
  175. if you need to capture more output.
  176. acpi_display_output= [HW,ACPI]
  177. acpi_display_output=vendor
  178. acpi_display_output=video
  179. See above.
  180. acpi_irq_balance [HW,ACPI]
  181. ACPI will balance active IRQs
  182. default in APIC mode
  183. acpi_irq_nobalance [HW,ACPI]
  184. ACPI will not move active IRQs (default)
  185. default in PIC mode
  186. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  187. Format: <irq>,<irq>...
  188. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  189. use by PCI
  190. Format: <irq>,<irq>...
  191. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  192. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  193. Format: To spoof as Windows 98: ="Microsoft Windows"
  194. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  195. acpi_osi="string1" # add string1 -- only one string
  196. acpi_osi="!string2" # remove built-in string2
  197. acpi_osi= # disable all strings
  198. acpi_pm_good [X86]
  199. Override the pmtimer bug detection: force the kernel
  200. to assume that this machine's pmtimer latches its value
  201. and always returns good values.
  202. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  203. Format: { level | edge | high | low }
  204. acpi_serialize [HW,ACPI] force serialization of AML methods
  205. acpi_skip_timer_override [HW,ACPI]
  206. Recognize and ignore IRQ0/pin2 Interrupt Override.
  207. For broken nForce2 BIOS resulting in XT-PIC timer.
  208. acpi_sleep= [HW,ACPI] Sleep options
  209. Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
  210. old_ordering, s4_nonvs, sci_force_enable }
  211. See Documentation/power/video.txt for information on
  212. s3_bios and s3_mode.
  213. s3_beep is for debugging; it makes the PC's speaker beep
  214. as soon as the kernel's real-mode entry point is called.
  215. s4_nohwsig prevents ACPI hardware signature from being
  216. used during resume from hibernation.
  217. old_ordering causes the ACPI 1.0 ordering of the _PTS
  218. control method, with respect to putting devices into
  219. low power states, to be enforced (the ACPI 2.0 ordering
  220. of _PTS is used by default).
  221. nonvs prevents the kernel from saving/restoring the
  222. ACPI NVS memory during suspend/hibernation and resume.
  223. sci_force_enable causes the kernel to set SCI_EN directly
  224. on resume from S1/S3 (which is against the ACPI spec,
  225. but some broken systems don't work without it).
  226. acpi_use_timer_override [HW,ACPI]
  227. Use timer override. For some broken Nvidia NF5 boards
  228. that require a timer override, but don't have HPET
  229. acpi_enforce_resources= [ACPI]
  230. { strict | lax | no }
  231. Check for resource conflicts between native drivers
  232. and ACPI OperationRegions (SystemIO and SystemMemory
  233. only). IO ports and memory declared in ACPI might be
  234. used by the ACPI subsystem in arbitrary AML code and
  235. can interfere with legacy drivers.
  236. strict (default): access to resources claimed by ACPI
  237. is denied; legacy drivers trying to access reserved
  238. resources will fail to bind to device using them.
  239. lax: access to resources claimed by ACPI is allowed;
  240. legacy drivers trying to access reserved resources
  241. will bind successfully but a warning message is logged.
  242. no: ACPI OperationRegions are not marked as reserved,
  243. no further checks are performed.
  244. ad1848= [HW,OSS]
  245. Format: <io>,<irq>,<dma>,<dma2>,<type>
  246. add_efi_memmap [EFI; X86] Include EFI memory map in
  247. kernel's map of available physical RAM.
  248. advansys= [HW,SCSI]
  249. See header of drivers/scsi/advansys.c.
  250. aedsp16= [HW,OSS] Audio Excel DSP 16
  251. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  252. See also header of sound/oss/aedsp16.c.
  253. agp= [AGP]
  254. { off | try_unsupported }
  255. off: disable AGP support
  256. try_unsupported: try to drive unsupported chipsets
  257. (may crash computer or cause data corruption)
  258. aha152x= [HW,SCSI]
  259. See Documentation/scsi/aha152x.txt.
  260. aha1542= [HW,SCSI]
  261. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  262. aic7xxx= [HW,SCSI]
  263. See Documentation/scsi/aic7xxx.txt.
  264. aic79xx= [HW,SCSI]
  265. See Documentation/scsi/aic79xx.txt.
  266. alignment= [KNL,ARM]
  267. Allow the default userspace alignment fault handler
  268. behaviour to be specified. Bit 0 enables warnings,
  269. bit 1 enables fixups, and bit 2 sends a segfault.
  270. amd_iommu= [HW,X86-84]
  271. Pass parameters to the AMD IOMMU driver in the system.
  272. Possible values are:
  273. fullflush - enable flushing of IO/TLB entries when
  274. they are unmapped. Otherwise they are
  275. flushed before they will be reused, which
  276. is a lot of faster
  277. off - do not initialize any AMD IOMMU found in
  278. the system
  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. autoconf= [IPV6]
  299. See Documentation/networking/ipv6.txt.
  300. show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
  301. Limit apic dumping. The parameter defines the maximal
  302. number of local apics being dumped. Also it is possible
  303. to set it to "all" by meaning -- no limit here.
  304. Format: { 1 (default) | 2 | ... | all }.
  305. The parameter valid if only apic=debug or
  306. apic=verbose is specified.
  307. Example: apic=debug show_lapic=all
  308. apm= [APM] Advanced Power Management
  309. See header of arch/x86/kernel/apm_32.c.
  310. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  311. Format: <io>,<irq>,<nodeID>
  312. ataflop= [HW,M68k]
  313. atarimouse= [HW,MOUSE] Atari Mouse
  314. atascsi= [HW,SCSI] Atari SCSI
  315. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  316. EzKey and similar keyboards
  317. atkbd.reset= [HW] Reset keyboard during initialization
  318. atkbd.set= [HW] Select keyboard code set
  319. Format: <int> (2 = AT (default), 3 = PS/2)
  320. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  321. keyboards
  322. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  323. Format: <bool> (0 = real, 1 = synthetic (default))
  324. atkbd.softrepeat= [HW]
  325. Use software keyboard repeat
  326. autotest [IA64]
  327. baycom_epp= [HW,AX25]
  328. Format: <io>,<mode>
  329. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  330. Format: <io>,<mode>
  331. See header of drivers/net/hamradio/baycom_par.c.
  332. baycom_ser_fdx= [HW,AX25]
  333. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  334. Format: <io>,<irq>,<mode>[,<baud>]
  335. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  336. baycom_ser_hdx= [HW,AX25]
  337. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  338. Format: <io>,<irq>,<mode>
  339. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  340. boot_delay= Milliseconds to delay each printk during boot.
  341. Values larger than 10 seconds (10000) are changed to
  342. no delay (0).
  343. Format: integer
  344. bootmem_debug [KNL] Enable bootmem allocator debug messages.
  345. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  346. bttv.radio= Most important insmod options are available as
  347. kernel args too.
  348. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  349. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  350. BusLogic= [HW,SCSI]
  351. See drivers/scsi/BusLogic.c, comment before function
  352. BusLogic_ParseDriverOptions().
  353. c101= [NET] Moxa C101 synchronous serial card
  354. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  355. Sometimes CPU hardware bugs make them report the cache
  356. size incorrectly. The kernel will attempt work arounds
  357. to fix known problems, but for some CPUs it is not
  358. possible to determine what the correct size should be.
  359. This option provides an override for these situations.
  360. capability.disable=
  361. [SECURITY] Disable capabilities. This would normally
  362. be used only if an alternative security model is to be
  363. configured. Potentially dangerous and should only be
  364. used if you are entirely sure of the consequences.
  365. ccw_timeout_log [S390]
  366. See Documentation/s390/CommonIO for details.
  367. cgroup_disable= [KNL] Disable a particular controller
  368. Format: {name of the controller(s) to disable}
  369. {Currently supported controllers - "memory"}
  370. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  371. Format: { "0" | "1" }
  372. See security/selinux/Kconfig help text.
  373. 0 -- check protection applied by kernel (includes
  374. any implied execute protection).
  375. 1 -- check protection requested by application.
  376. Default value is set via a kernel config option.
  377. Value can be changed at runtime via
  378. /selinux/checkreqprot.
  379. cio_ignore= [S390]
  380. See Documentation/s390/CommonIO for details.
  381. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  382. [Deprecated]
  383. Forces specified clocksource (if available) to be used
  384. when calculating gettimeofday(). If specified
  385. clocksource is not available, it defaults to PIT.
  386. Format: { pit | tsc | cyclone | pmtmr }
  387. clocksource= [GENERIC_TIME] Override the default clocksource
  388. Format: <string>
  389. Override the default clocksource and use the clocksource
  390. with the name specified.
  391. Some clocksource names to choose from, depending on
  392. the platform:
  393. [all] jiffies (this is the base, fallback clocksource)
  394. [ACPI] acpi_pm
  395. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  396. pxa_timer,timer3,32k_counter,timer0_1
  397. [AVR32] avr32
  398. [X86-32] pit,hpet,tsc,vmi-timer;
  399. scx200_hrt on Geode; cyclone on IBM x440
  400. [MIPS] MIPS
  401. [PARISC] cr16
  402. [S390] tod
  403. [SH] SuperH
  404. [SPARC64] tick
  405. [X86-64] hpet,tsc
  406. clearcpuid=BITNUM [X86]
  407. Disable CPUID feature X for the kernel. See
  408. arch/x86/include/asm/cpufeature.h for the valid bit
  409. numbers. Note the Linux specific bits are not necessarily
  410. stable over kernel options, but the vendor specific
  411. ones should be.
  412. Also note that user programs calling CPUID directly
  413. or using the feature without checking anything
  414. will still see it. This just prevents it from
  415. being used by the kernel or shown in /proc/cpuinfo.
  416. Also note the kernel might malfunction if you disable
  417. some critical bits.
  418. cmo_free_hint= [PPC] Format: { yes | no }
  419. Specify whether pages are marked as being inactive
  420. when they are freed. This is used in CMO environments
  421. to determine OS memory pressure for page stealing by
  422. a hypervisor.
  423. Default: yes
  424. code_bytes [X86] How many bytes of object code to print
  425. in an oops report.
  426. Range: 0 - 8192
  427. Default: 64
  428. com20020= [HW,NET] ARCnet - COM20020 chipset
  429. Format:
  430. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  431. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  432. Format: <io>[,<irq>]
  433. com90xx= [HW,NET]
  434. ARCnet - COM90xx chipset (memory-mapped buffers)
  435. Format: <io>[,<irq>[,<memstart>]]
  436. condev= [HW,S390] console device
  437. conmode=
  438. console= [KNL] Output console device and options.
  439. tty<n> Use the virtual console device <n>.
  440. ttyS<n>[,options]
  441. ttyUSB0[,options]
  442. Use the specified serial port. The options are of
  443. the form "bbbbpnf", where "bbbb" is the baud rate,
  444. "p" is parity ("n", "o", or "e"), "n" is number of
  445. bits, and "f" is flow control ("r" for RTS or
  446. omit it). Default is "9600n8".
  447. See Documentation/serial-console.txt for more
  448. information. See
  449. Documentation/networking/netconsole.txt for an
  450. alternative.
  451. uart[8250],io,<addr>[,options]
  452. uart[8250],mmio,<addr>[,options]
  453. Start an early, polled-mode console on the 8250/16550
  454. UART at the specified I/O port or MMIO address,
  455. switching to the matching ttyS device later. The
  456. options are the same as for ttyS, above.
  457. If the device connected to the port is not a TTY but a braille
  458. device, prepend "brl," before the device type, for instance
  459. console=brl,ttyS0
  460. For now, only VisioBraille is supported.
  461. consoleblank= [KNL] The console blank (screen saver) timeout in
  462. seconds. Defaults to 10*60 = 10mins. A value of 0
  463. disables the blank timer.
  464. coredump_filter=
  465. [KNL] Change the default value for
  466. /proc/<pid>/coredump_filter.
  467. See also Documentation/filesystems/proc.txt.
  468. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  469. Format:
  470. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  471. crashkernel=nn[KMG]@ss[KMG]
  472. [KNL] Reserve a chunk of physical memory to
  473. hold a kernel to switch to with kexec on panic.
  474. crashkernel=range1:size1[,range2:size2,...][@offset]
  475. [KNL] Same as above, but depends on the memory
  476. in the running system. The syntax of range is
  477. start-[end] where start and end are both
  478. a memory unit (amount[KMG]). See also
  479. Documentation/kdump/kdump.txt for a example.
  480. cs89x0_dma= [HW,NET]
  481. Format: <dma>
  482. cs89x0_media= [HW,NET]
  483. Format: { rj45 | aui | bnc }
  484. dasd= [HW,NET]
  485. See header of drivers/s390/block/dasd_devmap.c.
  486. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  487. (one device per port)
  488. Format: <port#>,<type>
  489. See also Documentation/input/joystick-parport.txt
  490. debug [KNL] Enable kernel debugging (events log level).
  491. debug_locks_verbose=
  492. [KNL] verbose self-tests
  493. Format=<0|1>
  494. Print debugging info while doing the locking API
  495. self-tests.
  496. We default to 0 (no extra messages), setting it to
  497. 1 will print _a lot_ more information - normally
  498. only useful to kernel developers.
  499. debug_objects [KNL] Enable object debugging
  500. no_debug_objects
  501. [KNL] Disable object debugging
  502. debugpat [X86] Enable PAT debugging
  503. decnet.addr= [HW,NET]
  504. Format: <area>[,<node>]
  505. See also Documentation/networking/decnet.txt.
  506. default_hugepagesz=
  507. [same as hugepagesz=] The size of the default
  508. HugeTLB page size. This is the size represented by
  509. the legacy /proc/ hugepages APIs, used for SHM, and
  510. default size when mounting hugetlbfs filesystems.
  511. Defaults to the default architecture's huge page size
  512. if not specified.
  513. dhash_entries= [KNL]
  514. Set number of hash buckets for dentry cache.
  515. digi= [HW,SERIAL]
  516. IO parameters + enable/disable command.
  517. digiepca= [HW,SERIAL]
  518. See drivers/char/README.epca and
  519. Documentation/serial/digiepca.txt.
  520. disable= [IPV6]
  521. See Documentation/networking/ipv6.txt.
  522. disable_ipv6= [IPV6]
  523. See Documentation/networking/ipv6.txt.
  524. disable_mtrr_cleanup [X86]
  525. The kernel tries to adjust MTRR layout from continuous
  526. to discrete, to make X server driver able to add WB
  527. entry later. This parameter disables that.
  528. disable_mtrr_trim [X86, Intel and AMD only]
  529. By default the kernel will trim any uncacheable
  530. memory out of your available memory pool based on
  531. MTRR settings. This parameter disables that behavior,
  532. possibly causing your machine to run very slowly.
  533. disable_timer_pin_1 [X86]
  534. Disable PIN 1 of APIC timer
  535. Can be useful to work around chipset bugs.
  536. dmasound= [HW,OSS] Sound subsystem buffers
  537. dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
  538. this option disables the debugging code at boot.
  539. dma_debug_entries=<number>
  540. This option allows to tune the number of preallocated
  541. entries for DMA-API debugging code. One entry is
  542. required per DMA-API allocation. Use this if the
  543. DMA-API debugging code disables itself because the
  544. architectural default is too low.
  545. dma_debug_driver=<driver_name>
  546. With this option the DMA-API debugging driver
  547. filter feature can be enabled at boot time. Just
  548. pass the driver to filter for as the parameter.
  549. The filter can be disabled or changed to another
  550. driver later using sysfs.
  551. dscc4.setup= [NET]
  552. dtc3181e= [HW,SCSI]
  553. dynamic_printk Enables pr_debug()/dev_dbg() calls if
  554. CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
  555. These can also be switched on/off via
  556. <debugfs>/dynamic_printk/modules
  557. earlycon= [KNL] Output early console device and options.
  558. uart[8250],io,<addr>[,options]
  559. uart[8250],mmio,<addr>[,options]
  560. Start an early, polled-mode console on the 8250/16550
  561. UART at the specified I/O port or MMIO address.
  562. The options are the same as for ttyS, above.
  563. earlyprintk= [X86,SH,BLACKFIN]
  564. earlyprintk=vga
  565. earlyprintk=serial[,ttySn[,baudrate]]
  566. earlyprintk=ttySn[,baudrate]
  567. earlyprintk=dbgp[debugController#]
  568. Append ",keep" to not disable it when the real console
  569. takes over.
  570. Only vga or serial or usb debug port at a time.
  571. Currently only ttyS0 and ttyS1 are supported.
  572. Interaction with the standard serial driver is not
  573. very good.
  574. The VGA output is eventually overwritten by the real
  575. console.
  576. ekgdboc= [X86,KGDB] Allow early kernel console debugging
  577. ekgdboc=kbd
  578. This is desgined to be used in conjunction with
  579. the boot argument: earlyprintk=vga
  580. eata= [HW,SCSI]
  581. edd= [EDD]
  582. Format: {"off" | "on" | "skip[mbr]"}
  583. eisa_irq_edge= [PARISC,HW]
  584. See header of drivers/parisc/eisa.c.
  585. elanfreq= [X86-32]
  586. See comment before function elanfreq_setup() in
  587. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
  588. elevator= [IOSCHED]
  589. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  590. See Documentation/block/as-iosched.txt and
  591. Documentation/block/deadline-iosched.txt for details.
  592. elfcorehdr= [IA64,PPC,SH,X86]
  593. Specifies physical address of start of kernel core
  594. image elf header. Generally kexec loader will
  595. pass this option to capture kernel.
  596. See Documentation/kdump/kdump.txt for details.
  597. enable_mtrr_cleanup [X86]
  598. The kernel tries to adjust MTRR layout from continuous
  599. to discrete, to make X server driver able to add WB
  600. entry later. This parameter enables that.
  601. enable_timer_pin_1 [X86]
  602. Enable PIN 1 of APIC timer
  603. Can be useful to work around chipset bugs
  604. (in particular on some ATI chipsets).
  605. The kernel tries to set a reasonable default.
  606. enforcing [SELINUX] Set initial enforcing status.
  607. Format: {"0" | "1"}
  608. See security/selinux/Kconfig help text.
  609. 0 -- permissive (log only, no denials).
  610. 1 -- enforcing (deny and log).
  611. Default value is 0.
  612. Value can be changed at runtime via /selinux/enforce.
  613. erst_disable [ACPI]
  614. Disable Error Record Serialization Table (ERST)
  615. support.
  616. ether= [HW,NET] Ethernet cards parameters
  617. This option is obsoleted by the "netdev=" option, which
  618. has equivalent usage. See its documentation for details.
  619. failslab=
  620. fail_page_alloc=
  621. fail_make_request=[KNL]
  622. General fault injection mechanism.
  623. Format: <interval>,<probability>,<space>,<times>
  624. See also /Documentation/fault-injection/.
  625. fd_mcs= [HW,SCSI]
  626. See header of drivers/scsi/fd_mcs.c.
  627. fdomain= [HW,SCSI]
  628. See header of drivers/scsi/fdomain.c.
  629. floppy= [HW]
  630. See Documentation/blockdev/floppy.txt.
  631. force_pal_cache_flush
  632. [IA-64] Avoid check_sal_cache_flush which may hang on
  633. buggy SAL_CACHE_FLUSH implementations. Using this
  634. parameter will force ia64_sal_cache_flush to call
  635. ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
  636. ftrace=[tracer]
  637. [FTRACE] will set and start the specified tracer
  638. as early as possible in order to facilitate early
  639. boot debugging.
  640. ftrace_dump_on_oops[=orig_cpu]
  641. [FTRACE] will dump the trace buffers on oops.
  642. If no parameter is passed, ftrace will dump
  643. buffers of all CPUs, but if you pass orig_cpu, it will
  644. dump only the buffer of the CPU that triggered the
  645. oops.
  646. ftrace_filter=[function-list]
  647. [FTRACE] Limit the functions traced by the function
  648. tracer at boot up. function-list is a comma separated
  649. list of functions. This list can be changed at run
  650. time by the set_ftrace_filter file in the debugfs
  651. tracing directory.
  652. ftrace_notrace=[function-list]
  653. [FTRACE] Do not trace the functions specified in
  654. function-list. This list can be changed at run time
  655. by the set_ftrace_notrace file in the debugfs
  656. tracing directory.
  657. ftrace_graph_filter=[function-list]
  658. [FTRACE] Limit the top level callers functions traced
  659. by the function graph tracer at boot up.
  660. function-list is a comma separated list of functions
  661. that can be changed at run time by the
  662. set_graph_function file in the debugfs tracing directory.
  663. gamecon.map[2|3]=
  664. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  665. support via parallel port (up to 5 devices per port)
  666. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  667. See also Documentation/input/joystick-parport.txt
  668. gamma= [HW,DRM]
  669. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  670. Format: off | on
  671. default: on
  672. gcov_persist= [GCOV] When non-zero (default), profiling data for
  673. kernel modules is saved and remains accessible via
  674. debugfs, even when the module is unloaded/reloaded.
  675. When zero, profiling data is discarded and associated
  676. debugfs files are removed at module unload time.
  677. gdth= [HW,SCSI]
  678. See header of drivers/scsi/gdth.c.
  679. gpt [EFI] Forces disk with valid GPT signature but
  680. invalid Protective MBR to be treated as GPT.
  681. gvp11= [HW,SCSI]
  682. hashdist= [KNL,NUMA] Large hashes allocated during boot
  683. are distributed across NUMA nodes. Defaults on
  684. for 64bit NUMA, off otherwise.
  685. Format: 0 | 1 (for off | on)
  686. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  687. hd= [EIDE] (E)IDE hard drive subsystem geometry
  688. Format: <cyl>,<head>,<sect>
  689. hest_disable [ACPI]
  690. Disable Hardware Error Source Table (HEST) support;
  691. corresponding firmware-first mode error processing
  692. logic will be disabled.
  693. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  694. size of <nn>. This works even on boxes that have no
  695. highmem otherwise. This also works to reduce highmem
  696. size on bigger boxes.
  697. highres= [KNL] Enable/disable high resolution timer mode.
  698. Valid parameters: "on", "off"
  699. Default: "on"
  700. hisax= [HW,ISDN]
  701. See Documentation/isdn/README.HiSax.
  702. hlt [BUGS=ARM,SH]
  703. hpet= [X86-32,HPET] option to control HPET usage
  704. Format: { enable (default) | disable | force |
  705. verbose }
  706. disable: disable HPET and use PIT instead
  707. force: allow force enabled of undocumented chips (ICH4,
  708. VIA, nVidia)
  709. verbose: show contents of HPET registers during setup
  710. hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
  711. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
  712. On x86-64 and powerpc, this option can be specified
  713. multiple times interleaved with hugepages= to reserve
  714. huge pages of different sizes. Valid pages sizes on
  715. x86-64 are 2M (when the CPU supports "pse") and 1G
  716. (when the CPU supports the "pdpe1gb" cpuinfo flag)
  717. Note that 1GB pages can only be allocated at boot time
  718. using hugepages= and not freed afterwards.
  719. hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
  720. terminal devices. Valid values: 0..8
  721. hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
  722. If specified, z/VM IUCV HVC accepts connections
  723. from listed z/VM user IDs only.
  724. i2c_bus= [HW] Override the default board specific I2C bus speed
  725. or register an additional I2C bus that is not
  726. registered from board initialization code.
  727. Format:
  728. <bus_id>,<clkrate>
  729. i8042.debug [HW] Toggle i8042 debug mode
  730. i8042.direct [HW] Put keyboard port into non-translated mode
  731. i8042.dumbkbd [HW] Pretend that controller can only read data from
  732. keyboard and cannot control its state
  733. (Don't attempt to blink the leds)
  734. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  735. i8042.nokbd [HW] Don't check/create keyboard port
  736. i8042.noloop [HW] Disable the AUX Loopback command while probing
  737. for the AUX port
  738. i8042.nomux [HW] Don't check presence of an active multiplexing
  739. controller
  740. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  741. controllers
  742. i8042.panicblink=
  743. [HW] Frequency with which keyboard LEDs should blink
  744. when kernel panics (default is 0.5 sec)
  745. i8042.reset [HW] Reset the controller during init and cleanup
  746. i8042.unlock [HW] Unlock (ignore) the keylock
  747. i810= [HW,DRM]
  748. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  749. indicates that the driver is running on unsupported
  750. hardware.
  751. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  752. does not match list of supported models.
  753. i8k.power_status
  754. [HW] Report power status in /proc/i8k
  755. (disabled by default)
  756. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  757. capability is set.
  758. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  759. See Documentation/mca.txt.
  760. icn= [HW,ISDN]
  761. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  762. ide-core.nodma= [HW] (E)IDE subsystem
  763. Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
  764. .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
  765. .cdrom .chs .ignore_cable are additional options
  766. See Documentation/ide/ide.txt.
  767. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  768. Claim all unknown PCI IDE storage controllers.
  769. idle= [X86]
  770. Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
  771. Poll forces a polling idle loop that can slightly
  772. improve the performance of waking up a idle CPU, but
  773. will use a lot of power and make the system run hot.
  774. Not recommended.
  775. idle=mwait: On systems which support MONITOR/MWAIT but
  776. the kernel chose to not use it because it doesn't save
  777. as much power as a normal idle loop, use the
  778. MONITOR/MWAIT idle loop anyways. Performance should be
  779. the same as idle=poll.
  780. idle=halt: Halt is forced to be used for CPU idle.
  781. In such case C2/C3 won't be used again.
  782. idle=nomwait: Disable mwait for CPU C-states
  783. ignore_loglevel [KNL]
  784. Ignore loglevel setting - this will print /all/
  785. kernel messages to the console. Useful for debugging.
  786. ihash_entries= [KNL]
  787. Set number of hash buckets for inode cache.
  788. ima_audit= [IMA]
  789. Format: { "0" | "1" }
  790. 0 -- integrity auditing messages. (Default)
  791. 1 -- enable informational integrity auditing messages.
  792. ima_hash= [IMA]
  793. Format: { "sha1" | "md5" }
  794. default: "sha1"
  795. ima_tcb [IMA]
  796. Load a policy which meets the needs of the Trusted
  797. Computing Base. This means IMA will measure all
  798. programs exec'd, files mmap'd for exec, and all files
  799. opened for read by uid=0.
  800. in2000= [HW,SCSI]
  801. See header of drivers/scsi/in2000.c.
  802. init= [KNL]
  803. Format: <full_path>
  804. Run specified binary instead of /sbin/init as init
  805. process.
  806. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  807. for working out where the kernel is dying during
  808. startup.
  809. initrd= [BOOT] Specify the location of the initial ramdisk
  810. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  811. Format: <irq>
  812. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  813. on
  814. Enable intel iommu driver.
  815. off
  816. Disable intel iommu driver.
  817. igfx_off [Default Off]
  818. By default, gfx is mapped as normal device. If a gfx
  819. device has a dedicated DMAR unit, the DMAR unit is
  820. bypassed by not enabling DMAR with this option. In
  821. this case, gfx device will use physical address for
  822. DMA.
  823. forcedac [x86_64]
  824. With this option iommu will not optimize to look
  825. for io virtual address below 32 bit forcing dual
  826. address cycle on pci bus for cards supporting greater
  827. than 32 bit addressing. The default is to look
  828. for translation below 32 bit and if not available
  829. then look in the higher range.
  830. strict [Default Off]
  831. With this option on every unmap_single operation will
  832. result in a hardware IOTLB flush operation as opposed
  833. to batching them for performance.
  834. inttest= [IA64]
  835. iomem= Disable strict checking of access to MMIO memory
  836. strict regions from userspace.
  837. relaxed
  838. iommu= [x86]
  839. off
  840. force
  841. noforce
  842. biomerge
  843. panic
  844. nopanic
  845. merge
  846. nomerge
  847. forcesac
  848. soft
  849. pt [x86, IA64]
  850. io7= [HW] IO7 for Marvel based alpha systems
  851. See comment before marvel_specify_io7 in
  852. arch/alpha/kernel/core_marvel.c.
  853. io_delay= [X86] I/O delay method
  854. 0x80
  855. Standard port 0x80 based delay
  856. 0xed
  857. Alternate port 0xed based delay (needed on some systems)
  858. udelay
  859. Simple two microseconds delay
  860. none
  861. No delay
  862. ip= [IP_PNP]
  863. See Documentation/filesystems/nfs/nfsroot.txt.
  864. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  865. See comment before ip2_setup() in
  866. drivers/char/ip2/ip2base.c.
  867. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  868. See header of drivers/scsi/ips.c.
  869. irqfixup [HW]
  870. When an interrupt is not handled search all handlers
  871. for it. Intended to get systems with badly broken
  872. firmware running.
  873. irqpoll [HW]
  874. When an interrupt is not handled search all handlers
  875. for it. Also check all handlers each timer
  876. interrupt. Intended to get systems with badly broken
  877. firmware running.
  878. isapnp= [ISAPNP]
  879. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  880. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  881. Format:
  882. <cpu number>,...,<cpu number>
  883. or
  884. <cpu number>-<cpu number>
  885. (must be a positive range in ascending order)
  886. or a mixture
  887. <cpu number>,...,<cpu number>-<cpu number>
  888. This option can be used to specify one or more CPUs
  889. to isolate from the general SMP balancing and scheduling
  890. algorithms. You can move a process onto or off an
  891. "isolated" CPU via the CPU affinity syscalls or cpuset.
  892. <cpu number> begins at 0 and the maximum value is
  893. "number of CPUs in system - 1".
  894. This option is the preferred way to isolate CPUs. The
  895. alternative -- manually setting the CPU mask of all
  896. tasks in the system -- can cause problems and
  897. suboptimal load balancer performance.
  898. iucv= [HW,NET]
  899. js= [HW,JOY] Analog joystick
  900. See Documentation/input/joystick.txt.
  901. keepinitrd [HW,ARM]
  902. kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  903. specifies the amount of memory usable by the kernel
  904. for non-movable allocations. The requested amount is
  905. spread evenly throughout all nodes in the system. The
  906. remaining memory in each node is used for Movable
  907. pages. In the event, a node is too small to have both
  908. kernelcore and Movable pages, kernelcore pages will
  909. take priority and other nodes will have a larger number
  910. of kernelcore pages. The Movable zone is used for the
  911. allocation of pages that may be reclaimed or moved
  912. by the page migration subsystem. This means that
  913. HugeTLB pages may not be allocated from this zone.
  914. Note that allocations like PTEs-from-HighMem still
  915. use the HighMem zone if it exists, and the Normal
  916. zone if it does not.
  917. kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
  918. Format: <Controller#>[,poll interval]
  919. The controller # is the number of the ehci usb debug
  920. port as it is probed via PCI. The poll interval is
  921. optional and is the number seconds in between
  922. each poll cycle to the debug port in case you need
  923. the functionality for interrupting the kernel with
  924. gdb or control-c on the dbgp connection. When
  925. not using this parameter you use sysrq-g to break into
  926. the kernel debugger.
  927. kgdboc= [KGDB,HW] kgdb over consoles.
  928. Requires a tty driver that supports console polling,
  929. or a supported polling keyboard driver (non-usb).
  930. Serial only format: <serial_device>[,baud]
  931. keyboard only format: kbd
  932. keyboard and serial format: kbd,<serial_device>[,baud]
  933. kgdbwait [KGDB] Stop kernel execution and enter the
  934. kernel debugger at the earliest opportunity.
  935. kmac= [MIPS] korina ethernet MAC address.
  936. Configure the RouterBoard 532 series on-chip
  937. Ethernet adapter MAC address.
  938. kmemleak= [KNL] Boot-time kmemleak enable/disable
  939. Valid arguments: on, off
  940. Default: on
  941. kstack=N [X86] Print N words from the kernel stack
  942. in oops dumps.
  943. kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
  944. Default is 0 (don't ignore, but inject #GP)
  945. kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
  946. Default is 1 (enabled)
  947. kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
  948. Default is 0 (off)
  949. kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
  950. for all guests.
  951. Default is 1 (enabled) if in 64bit or 32bit-PAE mode
  952. kvm-intel.bypass_guest_pf=
  953. [KVM,Intel] Disables bypassing of guest page faults
  954. on Intel chips. Default is 1 (enabled)
  955. kvm-intel.ept= [KVM,Intel] Disable extended page tables
  956. (virtualized MMU) support on capable Intel chips.
  957. Default is 1 (enabled)
  958. kvm-intel.emulate_invalid_guest_state=
  959. [KVM,Intel] Enable emulation of invalid guest states
  960. Default is 0 (disabled)
  961. kvm-intel.flexpriority=
  962. [KVM,Intel] Disable FlexPriority feature (TPR shadow).
  963. Default is 1 (enabled)
  964. kvm-intel.unrestricted_guest=
  965. [KVM,Intel] Disable unrestricted guest feature
  966. (virtualized real and unpaged mode) on capable
  967. Intel chips. Default is 1 (enabled)
  968. kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
  969. feature (tagged TLBs) on capable Intel chips.
  970. Default is 1 (enabled)
  971. l2cr= [PPC]
  972. l3cr= [PPC]
  973. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  974. disabled it.
  975. lapic_timer_c2_ok [X86,APIC] trust the local apic timer
  976. in C2 power state.
  977. libata.dma= [LIBATA] DMA control
  978. libata.dma=0 Disable all PATA and SATA DMA
  979. libata.dma=1 PATA and SATA Disk DMA only
  980. libata.dma=2 ATAPI (CDROM) DMA only
  981. libata.dma=4 Compact Flash DMA only
  982. Combinations also work, so libata.dma=3 enables DMA
  983. for disks and CDROMs, but not CFs.
  984. libata.ignore_hpa= [LIBATA] Ignore HPA limit
  985. libata.ignore_hpa=0 keep BIOS limits (default)
  986. libata.ignore_hpa=1 ignore limits, using full disk
  987. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  988. when set.
  989. Format: <int>
  990. libata.force= [LIBATA] Force configurations. The format is comma
  991. separated list of "[ID:]VAL" where ID is
  992. PORT[.DEVICE]. PORT and DEVICE are decimal numbers
  993. matching port, link or device. Basically, it matches
  994. the ATA ID string printed on console by libata. If
  995. the whole ID part is omitted, the last PORT and DEVICE
  996. values are used. If ID hasn't been specified yet, the
  997. configuration applies to all ports, links and devices.
  998. If only DEVICE is omitted, the parameter applies to
  999. the port and all links and devices behind it. DEVICE
  1000. number of 0 either selects the first device or the
  1001. first fan-out link behind PMP device. It does not
  1002. select the host link. DEVICE number of 15 selects the
  1003. host link and device attached to it.
  1004. The VAL specifies the configuration to force. As long
  1005. as there's no ambiguity shortcut notation is allowed.
  1006. For example, both 1.5 and 1.5G would work for 1.5Gbps.
  1007. The following configurations can be forced.
  1008. * Cable type: 40c, 80c, short40c, unk, ign or sata.
  1009. Any ID with matching PORT is used.
  1010. * SATA link speed limit: 1.5Gbps or 3.0Gbps.
  1011. * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
  1012. udma[/][16,25,33,44,66,100,133] notation is also
  1013. allowed.
  1014. * [no]ncq: Turn on or off NCQ.
  1015. * nohrst, nosrst, norst: suppress hard, soft
  1016. and both resets.
  1017. * dump_id: dump IDENTIFY data.
  1018. If there are multiple matching configurations changing
  1019. the same attribute, the last one is used.
  1020. memblock=debug [KNL] Enable memblock debug messages.
  1021. load_ramdisk= [RAM] List of ramdisks to load from floppy
  1022. See Documentation/blockdev/ramdisk.txt.
  1023. lockd.nlm_grace_period=P [NFS] Assign grace period.
  1024. Format: <integer>
  1025. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  1026. Format: <integer>
  1027. lockd.nlm_timeout=T [NFS] Assign timeout value.
  1028. Format: <integer>
  1029. lockd.nlm_udpport=M [NFS] Assign UDP port.
  1030. Format: <integer>
  1031. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  1032. Format: <irq>
  1033. loglevel= All Kernel Messages with a loglevel smaller than the
  1034. console loglevel will be printed to the console. It can
  1035. also be changed with klogd or other programs. The
  1036. loglevels are defined as follows:
  1037. 0 (KERN_EMERG) system is unusable
  1038. 1 (KERN_ALERT) action must be taken immediately
  1039. 2 (KERN_CRIT) critical conditions
  1040. 3 (KERN_ERR) error conditions
  1041. 4 (KERN_WARNING) warning conditions
  1042. 5 (KERN_NOTICE) normal but significant condition
  1043. 6 (KERN_INFO) informational
  1044. 7 (KERN_DEBUG) debug-level messages
  1045. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  1046. Format: { n | nk | nM }
  1047. n must be a power of two. The default size
  1048. is set in the kernel config file.
  1049. logo.nologo [FB] Disables display of the built-in Linux logo.
  1050. This may be used to provide more screen space for
  1051. kernel log messages and is useful when debugging
  1052. kernel boot problems.
  1053. lp=0 [LP] Specify parallel ports to use, e.g,
  1054. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  1055. lp=reset first parallel port). 'lp=0' disables the
  1056. lp=auto printer driver. 'lp=reset' (which can be
  1057. specified in addition to the ports) causes
  1058. attached printers to be reset. Using
  1059. lp=port1,port2,... specifies the parallel ports
  1060. to associate lp devices with, starting with
  1061. lp0. A port specification may be 'none' to skip
  1062. that lp device, or a parport name such as
  1063. 'parport0'. Specifying 'lp=auto' instead of a
  1064. port specification list means that device IDs
  1065. from each port should be examined, to see if
  1066. an IEEE 1284-compliant printer is attached; if
  1067. so, the driver will manage that printer.
  1068. See also header of drivers/char/lp.c.
  1069. lpj=n [KNL]
  1070. Sets loops_per_jiffy to given constant, thus avoiding
  1071. time-consuming boot-time autodetection (up to 250 ms per
  1072. CPU). 0 enables autodetection (default). To determine
  1073. the correct value for your kernel, boot with normal
  1074. autodetection and see what value is printed. Note that
  1075. on SMP systems the preset will be applied to all CPUs,
  1076. which is likely to cause problems if your CPUs need
  1077. significantly divergent settings. An incorrect value
  1078. will cause delays in the kernel to be wrong, leading to
  1079. unpredictable I/O errors and other breakage. Although
  1080. unlikely, in the extreme case this might damage your
  1081. hardware.
  1082. ltpc= [NET]
  1083. Format: <io>,<irq>,<dma>
  1084. mac5380= [HW,SCSI] Format:
  1085. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  1086. machvec= [IA64] Force the use of a particular machine-vector
  1087. (machvec) in a generic kernel.
  1088. Example: machvec=hpzx1_swiotlb
  1089. machtype= [Loongson] Share the same kernel image file between different
  1090. yeeloong laptop.
  1091. Example: machtype=lemote-yeeloong-2f-7inch
  1092. max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
  1093. than or equal to this physical address is ignored.
  1094. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  1095. should make use of. maxcpus=n : n >= 0 limits the
  1096. kernel to using 'n' processors. n=0 is a special case,
  1097. it is equivalent to "nosmp", which also disables
  1098. the IO APIC.
  1099. max_loop= [LOOP] Maximum number of loopback devices that can
  1100. be mounted
  1101. Format: <1-256>
  1102. max_luns= [SCSI] Maximum number of LUNs to probe.
  1103. Should be between 1 and 2^32-1.
  1104. max_report_luns=
  1105. [SCSI] Maximum number of LUNs received.
  1106. Should be between 1 and 16384.
  1107. mcatest= [IA-64]
  1108. mce [X86-32] Machine Check Exception
  1109. mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
  1110. md= [HW] RAID subsystems devices and level
  1111. See Documentation/md.txt.
  1112. mdacon= [MDA]
  1113. Format: <first>,<last>
  1114. Specifies range of consoles to be captured by the MDA.
  1115. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  1116. Amount of memory to be used when the kernel is not able
  1117. to see the whole system memory or for test.
  1118. [X86-32] Use together with memmap= to avoid physical
  1119. address space collisions. Without memmap= PCI devices
  1120. could be placed at addresses belonging to unused RAM.
  1121. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  1122. memory.
  1123. memchunk=nn[KMG]
  1124. [KNL,SH] Allow user to override the default size for
  1125. per-device physically contiguous DMA buffers.
  1126. memmap=exactmap [KNL,X86] Enable setting of an exact
  1127. E820 memory map, as specified by the user.
  1128. Such memmap=exactmap lines can be constructed based on
  1129. BIOS output or other requirements. See the memmap=nn@ss
  1130. option description.
  1131. memmap=nn[KMG]@ss[KMG]
  1132. [KNL] Force usage of a specific region of memory
  1133. Region of memory to be used, from ss to ss+nn.
  1134. memmap=nn[KMG]#ss[KMG]
  1135. [KNL,ACPI] Mark specific memory as ACPI data.
  1136. Region of memory to be used, from ss to ss+nn.
  1137. memmap=nn[KMG]$ss[KMG]
  1138. [KNL,ACPI] Mark specific memory as reserved.
  1139. Region of memory to be used, from ss to ss+nn.
  1140. Example: Exclude memory from 0x18690000-0x1869ffff
  1141. memmap=64K$0x18690000
  1142. or
  1143. memmap=0x10000$0x18690000
  1144. memory_corruption_check=0/1 [X86]
  1145. Some BIOSes seem to corrupt the first 64k of
  1146. memory when doing things like suspend/resume.
  1147. Setting this option will scan the memory
  1148. looking for corruption. Enabling this will
  1149. both detect corruption and prevent the kernel
  1150. from using the memory being corrupted.
  1151. However, its intended as a diagnostic tool; if
  1152. repeatable BIOS-originated corruption always
  1153. affects the same memory, you can use memmap=
  1154. to prevent the kernel from using that memory.
  1155. memory_corruption_check_size=size [X86]
  1156. By default it checks for corruption in the low
  1157. 64k, making this memory unavailable for normal
  1158. use. Use this parameter to scan for
  1159. corruption in more or less memory.
  1160. memory_corruption_check_period=seconds [X86]
  1161. By default it checks for corruption every 60
  1162. seconds. Use this parameter to check at some
  1163. other rate. 0 disables periodic checking.
  1164. memtest= [KNL,X86] Enable memtest
  1165. Format: <integer>
  1166. default : 0 <disable>
  1167. Specifies the number of memtest passes to be
  1168. performed. Each pass selects another test
  1169. pattern from a given set of patterns. Memtest
  1170. fills the memory with this pattern, validates
  1171. memory contents and reserves bad memory
  1172. regions that are detected.
  1173. meye.*= [HW] Set MotionEye Camera parameters
  1174. See Documentation/video4linux/meye.txt.
  1175. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  1176. Multi-Function General Purpose Timers on AMD Geode
  1177. platforms.
  1178. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  1179. the BIOS has incorrectly applied a workaround. TinyBIOS
  1180. version 0.98 is known to be affected, 0.99 fixes the
  1181. problem by letting the user disable the workaround.
  1182. mga= [HW,DRM]
  1183. min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
  1184. physical address is ignored.
  1185. mini2440= [ARM,HW,KNL]
  1186. Format:[0..2][b][c][t]
  1187. Default: "0tb"
  1188. MINI2440 configuration specification:
  1189. 0 - The attached screen is the 3.5" TFT
  1190. 1 - The attached screen is the 7" TFT
  1191. 2 - The VGA Shield is attached (1024x768)
  1192. Leaving out the screen size parameter will not load
  1193. the TFT driver, and the framebuffer will be left
  1194. unconfigured.
  1195. b - Enable backlight. The TFT backlight pin will be
  1196. linked to the kernel VESA blanking code and a GPIO
  1197. LED. This parameter is not necessary when using the
  1198. VGA shield.
  1199. c - Enable the s3c camera interface.
  1200. t - Reserved for enabling touchscreen support. The
  1201. touchscreen support is not enabled in the mainstream
  1202. kernel as of 2.6.30, a preliminary port can be found
  1203. in the "bleeding edge" mini2440 support kernel at
  1204. http://repo.or.cz/w/linux-2.6/mini2440.git
  1205. mminit_loglevel=
  1206. [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
  1207. parameter allows control of the logging verbosity for
  1208. the additional memory initialisation checks. A value
  1209. of 0 disables mminit logging and a level of 4 will
  1210. log everything. Information is printed at KERN_DEBUG
  1211. so loglevel=8 may also need to be specified.
  1212. mousedev.tap_time=
  1213. [MOUSE] Maximum time between finger touching and
  1214. leaving touchpad surface for touch to be considered
  1215. a tap and be reported as a left button click (for
  1216. touchpads working in absolute mode only).
  1217. Format: <msecs>
  1218. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  1219. reporting absolute coordinates, such as tablets
  1220. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  1221. reporting absolute coordinates, such as tablets
  1222. movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  1223. is similar to kernelcore except it specifies the
  1224. amount of memory used for migratable allocations.
  1225. If both kernelcore and movablecore is specified,
  1226. then kernelcore will be at *least* the specified
  1227. value but may be more. If movablecore on its own
  1228. is specified, the administrator must be careful
  1229. that the amount of memory usable for all allocations
  1230. is not too small.
  1231. mpu401= [HW,OSS]
  1232. Format: <io>,<irq>
  1233. MTD_Partition= [MTD]
  1234. Format: <name>,<region-number>,<size>,<offset>
  1235. MTD_Region= [MTD] Format:
  1236. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  1237. mtdparts= [MTD]
  1238. See drivers/mtd/cmdlinepart.c.
  1239. onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
  1240. Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
  1241. boundary - index of last SLC block on Flex-OneNAND.
  1242. The remaining blocks are configured as MLC blocks.
  1243. lock - Configure if Flex-OneNAND boundary should be locked.
  1244. Once locked, the boundary cannot be changed.
  1245. 1 indicates lock status, 0 indicates unlock status.
  1246. mtdset= [ARM]
  1247. ARM/S3C2412 JIVE boot control
  1248. See arch/arm/mach-s3c2412/mach-jive.c
  1249. mtouchusb.raw_coordinates=
  1250. [HW] Make the MicroTouch USB driver use raw coordinates
  1251. ('y', default) or cooked coordinates ('n')
  1252. mtrr_chunk_size=nn[KMG] [X86]
  1253. used for mtrr cleanup. It is largest continuous chunk
  1254. that could hold holes aka. UC entries.
  1255. mtrr_gran_size=nn[KMG] [X86]
  1256. Used for mtrr cleanup. It is granularity of mtrr block.
  1257. Default is 1.
  1258. Large value could prevent small alignment from
  1259. using up MTRRs.
  1260. mtrr_spare_reg_nr=n [X86]
  1261. Format: <integer>
  1262. Range: 0,7 : spare reg number
  1263. Default : 1
  1264. Used for mtrr cleanup. It is spare mtrr entries number.
  1265. Set to 2 or more if your graphical card needs more.
  1266. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  1267. NCR_D700= [HW,SCSI]
  1268. See header of drivers/scsi/NCR_D700.c.
  1269. ncr5380= [HW,SCSI]
  1270. ncr53c400= [HW,SCSI]
  1271. ncr53c400a= [HW,SCSI]
  1272. ncr53c406a= [HW,SCSI]
  1273. ncr53c8xx= [HW,SCSI]
  1274. netdev= [NET] Network devices parameters
  1275. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  1276. Note that mem_start is often overloaded to mean
  1277. something different and driver-specific.
  1278. This usage is only documented in each driver source
  1279. file if at all.
  1280. nf_conntrack.acct=
  1281. [NETFILTER] Enable connection tracking flow accounting
  1282. 0 to disable accounting
  1283. 1 to enable accounting
  1284. Default value is 0.
  1285. nfsaddrs= [NFS]
  1286. See Documentation/filesystems/nfs/nfsroot.txt.
  1287. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  1288. See Documentation/filesystems/nfs/nfsroot.txt.
  1289. nfs.callback_tcpport=
  1290. [NFS] set the TCP port on which the NFSv4 callback
  1291. channel should listen.
  1292. nfs.cache_getent=
  1293. [NFS] sets the pathname to the program which is used
  1294. to update the NFS client cache entries.
  1295. nfs.cache_getent_timeout=
  1296. [NFS] sets the timeout after which an attempt to
  1297. update a cache entry is deemed to have failed.
  1298. nfs.idmap_cache_timeout=
  1299. [NFS] set the maximum lifetime for idmapper cache
  1300. entries.
  1301. nfs.enable_ino64=
  1302. [NFS] enable 64-bit inode numbers.
  1303. If zero, the NFS client will fake up a 32-bit inode
  1304. number for the readdir() and stat() syscalls instead
  1305. of returning the full 64-bit number.
  1306. The default is to return 64-bit inode numbers.
  1307. nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
  1308. when a NMI is triggered.
  1309. Format: [state][,regs][,debounce][,die]
  1310. nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
  1311. Format: [panic,][num]
  1312. Valid num: 0,1,2
  1313. 0 - turn nmi_watchdog off
  1314. 1 - use the IO-APIC timer for the NMI watchdog
  1315. 2 - use the local APIC for the NMI watchdog using
  1316. a performance counter. Note: This will use one
  1317. performance counter and the local APIC's performance
  1318. vector.
  1319. When panic is specified, panic when an NMI watchdog
  1320. timeout occurs.
  1321. This is useful when you use a panic=... timeout and
  1322. need the box quickly up again.
  1323. Instead of 1 and 2 it is possible to use the following
  1324. symbolic names: lapic and ioapic
  1325. Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
  1326. netpoll.carrier_timeout=
  1327. [NET] Specifies amount of time (in seconds) that
  1328. netpoll should wait for a carrier. By default netpoll
  1329. waits 4 seconds.
  1330. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  1331. emulation library even if a 387 maths coprocessor
  1332. is present.
  1333. no_console_suspend
  1334. [HW] Never suspend the console
  1335. Disable suspending of consoles during suspend and
  1336. hibernate operations. Once disabled, debugging
  1337. messages can reach various consoles while the rest
  1338. of the system is being put to sleep (ie, while
  1339. debugging driver suspend/resume hooks). This may
  1340. not work reliably with all consoles, but is known
  1341. to work with serial and VGA consoles.
  1342. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  1343. caches in the slab allocator. Saves per-node memory,
  1344. but will impact performance.
  1345. noalign [KNL,ARM]
  1346. noapic [SMP,APIC] Tells the kernel to not make use of any
  1347. IOAPICs that may be present in the system.
  1348. nobats [PPC] Do not use BATs for mapping kernel lowmem
  1349. on "Classic" PPC cores.
  1350. nocache [ARM]
  1351. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  1352. nodelayacct [KNL] Disable per-task delay accounting
  1353. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  1354. nodsp [SH] Disable hardware DSP at boot time.
  1355. noefi [X86] Disable EFI runtime services support.
  1356. noexec [IA-64]
  1357. noexec [X86]
  1358. On X86-32 available only on PAE configured kernels.
  1359. noexec=on: enable non-executable mappings (default)
  1360. noexec=off: disable non-executable mappings
  1361. noexec32 [X86-64]
  1362. This affects only 32-bit executables.
  1363. noexec32=on: enable non-executable mappings (default)
  1364. read doesn't imply executable mappings
  1365. noexec32=off: disable non-executable mappings
  1366. read implies executable mappings
  1367. nofpu [SH] Disable hardware FPU at boot time.
  1368. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  1369. register save and restore. The kernel will only save
  1370. legacy floating-point registers on task switch.
  1371. noxsave [BUGS=X86] Disables x86 extended register state save
  1372. and restore using xsave. The kernel will fallback to
  1373. enabling legacy floating-point and sse state.
  1374. nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
  1375. wfi(ARM) instruction doesn't work correctly and not to
  1376. use it. This is also useful when using JTAG debugger.
  1377. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  1378. instruction doesn't work correctly and not to
  1379. use it.
  1380. no_file_caps Tells the kernel not to honor file capabilities. The
  1381. only way then for a file to be executed with privilege
  1382. is to be setuid root or executed by root.
  1383. nohalt [IA-64] Tells the kernel not to use the power saving
  1384. function PAL_HALT_LIGHT when idle. This increases
  1385. power-consumption. On the positive side, it reduces
  1386. interrupt wake-up latency, which may improve performance
  1387. in certain environments such as networked servers or
  1388. real-time systems.
  1389. nohz= [KNL] Boottime enable/disable dynamic ticks
  1390. Valid arguments: on, off
  1391. Default: on
  1392. noiotrap [SH] Disables trapped I/O port accesses.
  1393. noirqdebug [X86-32] Disables the code which attempts to detect and
  1394. disable unhandled interrupt sources.
  1395. no_timer_check [X86,APIC] Disables the code which tests for
  1396. broken timer IRQ sources.
  1397. noisapnp [ISAPNP] Disables ISA PnP code.
  1398. noinitrd [RAM] Tells the kernel not to load any configured
  1399. initial RAM disk.
  1400. nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
  1401. remapping.
  1402. nointroute [IA-64]
  1403. nojitter [IA64] Disables jitter checking for ITC timers.
  1404. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  1405. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  1406. noltlbs [PPC] Do not use large page/tlb entries for kernel
  1407. lowmem mapping on PPC40x.
  1408. nomca [IA-64] Disable machine check abort handling
  1409. nomce [X86-32] Machine Check Exception
  1410. nomfgpt [X86-32] Disable Multi-Function General Purpose
  1411. Timer usage (for AMD Geode machines).
  1412. nopat [X86] Disable PAT (page attribute table extension of
  1413. pagetables) support.
  1414. norandmaps Don't use address space randomization. Equivalent to
  1415. echo 0 > /proc/sys/kernel/randomize_va_space
  1416. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  1417. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1418. with UP alternatives
  1419. noresidual [PPC] Don't use residual data on PReP machines.
  1420. noresume [SWSUSP] Disables resume and restores original swap
  1421. space.
  1422. no-scroll [VGA] Disables scrollback.
  1423. This is required for the Braillex ib80-piezo Braille
  1424. reader made by F.H. Papenmeier (Germany).
  1425. nosbagart [IA-64]
  1426. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1427. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1428. and disable the IO APIC. legacy for "maxcpus=0".
  1429. nosoftlockup [KNL] Disable the soft-lockup detector.
  1430. noswapaccount [KNL] Disable accounting of swap in memory resource
  1431. controller. (See Documentation/cgroups/memory.txt)
  1432. nosync [HW,M68K] Disables sync negotiation for all devices.
  1433. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1434. nousb [USB] Disable the USB subsystem
  1435. nowb [ARM]
  1436. nox2apic [X86-64,APIC] Do not enable x2APIC mode.
  1437. nptcg= [IA64] Override max number of concurrent global TLB
  1438. purges which is reported from either PAL_VM_SUMMARY or
  1439. SAL PALO.
  1440. nr_cpus= [SMP] Maximum number of processors that an SMP kernel
  1441. could support. nr_cpus=n : n >= 1 limits the kernel to
  1442. supporting 'n' processors. Later in runtime you can not
  1443. use hotplug cpu feature to put more cpu back to online.
  1444. just like you compile the kernel NR_CPUS=n
  1445. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1446. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1447. one of ['zone', 'node', 'default'] can be specified
  1448. This can be set from sysctl after boot.
  1449. See Documentation/sysctl/vm.txt for details.
  1450. ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
  1451. See Documentation/debugging-via-ohci1394.txt for more
  1452. info.
  1453. olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
  1454. Rather than timing out after 20 ms if an EC
  1455. command is not properly ACKed, override the length
  1456. of the timeout. We have interrupts disabled while
  1457. waiting for the ACK, so if this is set too high
  1458. interrupts *may* be lost!
  1459. omap_mux= [OMAP] Override bootloader pin multiplexing.
  1460. Format: <mux_mode0.mode_name=value>...
  1461. For example, to override I2C bus2:
  1462. omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
  1463. opl3= [HW,OSS]
  1464. Format: <io>
  1465. oprofile.timer= [HW]
  1466. Use timer interrupt instead of performance counters
  1467. oprofile.cpu_type= Force an oprofile cpu type
  1468. This might be useful if you have an older oprofile
  1469. userland or if you want common events.
  1470. Format: { arch_perfmon }
  1471. arch_perfmon: [X86] Force use of architectural
  1472. perfmon on Intel CPUs instead of the
  1473. CPU specific event set.
  1474. osst= [HW,SCSI] SCSI Tape Driver
  1475. Format: <buffer_size>,<write_threshold>
  1476. See also Documentation/scsi/st.txt.
  1477. panic= [KNL] Kernel behaviour on panic
  1478. Format: <timeout>
  1479. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1480. connected to, default is 0.
  1481. Format: <parport#>
  1482. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1483. 0 for XT, 1 for AT (default is AT).
  1484. Format: <mode>
  1485. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1486. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1487. Use 'auto' to force the driver to use any
  1488. IRQ/DMA settings detected (the default is to
  1489. ignore detected IRQ/DMA settings because of
  1490. possible conflicts). You can specify the base
  1491. address, IRQ, and DMA settings; IRQ and DMA
  1492. should be numbers, or 'auto' (for using detected
  1493. settings on that particular port), or 'nofifo'
  1494. (to avoid using a FIFO even if it is detected).
  1495. Parallel ports are assigned in the order they
  1496. are specified on the command line, starting
  1497. with parport0.
  1498. parport_init_mode= [HW,PPT]
  1499. Configure VIA parallel port to operate in
  1500. a specific mode. This is necessary on Pegasos
  1501. computer where firmware has no options for setting
  1502. up parallel port mode and sets it to spp.
  1503. Currently this function knows 686a and 8231 chips.
  1504. Format: [spp|ps2|epp|ecp|ecpepp]
  1505. pas2= [HW,OSS] Format:
  1506. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1507. pas16= [HW,SCSI]
  1508. See header of drivers/scsi/pas16.c.
  1509. pause_on_oops=
  1510. Halt all CPUs after the first oops has been printed for
  1511. the specified number of seconds. This is to be used if
  1512. your oopses keep scrolling off the screen.
  1513. pcbit= [HW,ISDN]
  1514. pcd. [PARIDE]
  1515. See header of drivers/block/paride/pcd.c.
  1516. See also Documentation/blockdev/paride.txt.
  1517. pci=option[,option...] [PCI] various PCI subsystem options:
  1518. earlydump [X86] dump PCI config space before the kernel
  1519. changes anything
  1520. off [X86] don't probe for the PCI bus
  1521. bios [X86-32] force use of PCI BIOS, don't access
  1522. the hardware directly. Use this if your machine
  1523. has a non-standard PCI host bridge.
  1524. nobios [X86-32] disallow use of PCI BIOS, only direct
  1525. hardware access methods are allowed. Use this
  1526. if you experience crashes upon bootup and you
  1527. suspect they are caused by the BIOS.
  1528. conf1 [X86] Force use of PCI Configuration
  1529. Mechanism 1.
  1530. conf2 [X86] Force use of PCI Configuration
  1531. Mechanism 2.
  1532. noaer [PCIE] If the PCIEAER kernel config parameter is
  1533. enabled, this kernel boot option can be used to
  1534. disable the use of PCIE advanced error reporting.
  1535. nodomains [PCI] Disable support for multiple PCI
  1536. root domains (aka PCI segments, in ACPI-speak).
  1537. nommconf [X86] Disable use of MMCONFIG for PCI
  1538. Configuration
  1539. check_enable_amd_mmconf [X86] check for and enable
  1540. properly configured MMIO access to PCI
  1541. config space on AMD family 10h CPU
  1542. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1543. enabled, this kernel boot option can be used to
  1544. disable the use of MSI interrupts system-wide.
  1545. noioapicquirk [APIC] Disable all boot interrupt quirks.
  1546. Safety option to keep boot IRQs enabled. This
  1547. should never be necessary.
  1548. ioapicreroute [APIC] Enable rerouting of boot IRQs to the
  1549. primary IO-APIC for bridges that cannot disable
  1550. boot IRQs. This fixes a source of spurious IRQs
  1551. when the system masks IRQs.
  1552. noioapicreroute [APIC] Disable workaround that uses the
  1553. boot IRQ equivalent of an IRQ that connects to
  1554. a chipset where boot IRQs cannot be disabled.
  1555. The opposite of ioapicreroute.
  1556. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1557. routing table. These calls are known to be buggy
  1558. on several machines and they hang the machine
  1559. when used, but on other computers it's the only
  1560. way to get the interrupt routing table. Try
  1561. this option if the kernel is unable to allocate
  1562. IRQs or discover secondary PCI buses on your
  1563. motherboard.
  1564. rom [X86] Assign address space to expansion ROMs.
  1565. Use with caution as certain devices share
  1566. address decoders between ROMs and other
  1567. resources.
  1568. norom [X86] Do not assign address space to
  1569. expansion ROMs that do not already have
  1570. BIOS assigned address ranges.
  1571. irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
  1572. assigned automatically to PCI devices. You can
  1573. make the kernel exclude IRQs of your ISA cards
  1574. this way.
  1575. pirqaddr=0xAAAAA [X86] Specify the physical address
  1576. of the PIRQ table (normally generated
  1577. by the BIOS) if it is outside the
  1578. F0000h-100000h range.
  1579. lastbus=N [X86] Scan all buses thru bus #N. Can be
  1580. useful if the kernel is unable to find your
  1581. secondary buses and you want to tell it
  1582. explicitly which ones they are.
  1583. assign-busses [X86] Always assign all PCI bus
  1584. numbers ourselves, overriding
  1585. whatever the firmware may have done.
  1586. usepirqmask [X86] Honor the possible IRQ mask stored
  1587. in the BIOS $PIR table. This is needed on
  1588. some systems with broken BIOSes, notably
  1589. some HP Pavilion N5400 and Omnibook XE3
  1590. notebooks. This will have no effect if ACPI
  1591. IRQ routing is enabled.
  1592. noacpi [X86] Do not use ACPI for IRQ routing
  1593. or for PCI scanning.
  1594. use_crs [X86] Use PCI host bridge window information
  1595. from ACPI. On BIOSes from 2008 or later, this
  1596. is enabled by default. If you need to use this,
  1597. please report a bug.
  1598. nocrs [X86] Ignore PCI host bridge windows from ACPI.
  1599. If you need to use this, please report a bug.
  1600. routeirq Do IRQ routing for all PCI devices.
  1601. This is normally done in pci_enable_device(),
  1602. so this option is a temporary workaround
  1603. for broken drivers that don't call it.
  1604. skip_isa_align [X86] do not align io start addr, so can
  1605. handle more pci cards
  1606. firmware [ARM] Do not re-enumerate the bus but instead
  1607. just use the configuration from the
  1608. bootloader. This is currently used on
  1609. IXP2000 systems where the bus has to be
  1610. configured a certain way for adjunct CPUs.
  1611. noearly [X86] Don't do any early type 1 scanning.
  1612. This might help on some broken boards which
  1613. machine check when some devices' config space
  1614. is read. But various workarounds are disabled
  1615. and some IOMMU drivers will not work.
  1616. bfsort Sort PCI devices into breadth-first order.
  1617. This sorting is done to get a device
  1618. order compatible with older (<= 2.4) kernels.
  1619. nobfsort Don't sort PCI devices into breadth-first order.
  1620. cbiosize=nn[KMG] The fixed amount of bus space which is
  1621. reserved for the CardBus bridge's IO window.
  1622. The default value is 256 bytes.
  1623. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1624. reserved for the CardBus bridge's memory
  1625. window. The default value is 64 megabytes.
  1626. resource_alignment=
  1627. Format:
  1628. [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
  1629. Specifies alignment and device to reassign
  1630. aligned memory resources.
  1631. If <order of align> is not specified,
  1632. PAGE_SIZE is used as alignment.
  1633. PCI-PCI bridge can be specified, if resource
  1634. windows need to be expanded.
  1635. ecrc= Enable/disable PCIe ECRC (transaction layer
  1636. end-to-end CRC checking).
  1637. bios: Use BIOS/firmware settings. This is the
  1638. the default.
  1639. off: Turn ECRC off
  1640. on: Turn ECRC on.
  1641. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
  1642. Management.
  1643. off Disable ASPM.
  1644. force Enable ASPM even on devices that claim not to support it.
  1645. WARNING: Forcing ASPM on may cause system lockups.
  1646. pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
  1647. Format: {auto|force}[,nomsi]
  1648. auto Use native PCIe PME signaling if the BIOS allows the
  1649. kernel to control PCIe config registers of root ports.
  1650. force Use native PCIe PME signaling even if the BIOS refuses
  1651. to allow the kernel to control the relevant PCIe config
  1652. registers.
  1653. nomsi Do not use MSI for native PCIe PME signaling (this makes
  1654. all PCIe root ports use INTx for everything).
  1655. pcmv= [HW,PCMCIA] BadgePAD 4
  1656. pd. [PARIDE]
  1657. See Documentation/blockdev/paride.txt.
  1658. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1659. boot time.
  1660. Format: { 0 | 1 }
  1661. See arch/parisc/kernel/pdc_chassis.c
  1662. percpu_alloc= Select which percpu first chunk allocator to use.
  1663. Currently supported values are "embed" and "page".
  1664. Archs may support subset or none of the selections.
  1665. See comments in mm/percpu.c for details on each
  1666. allocator. This parameter is primarily for debugging
  1667. and performance comparison.
  1668. pf. [PARIDE]
  1669. See Documentation/blockdev/paride.txt.
  1670. pg. [PARIDE]
  1671. See Documentation/blockdev/paride.txt.
  1672. pirq= [SMP,APIC] Manual mp-table setup
  1673. See Documentation/x86/i386/IO-APIC.txt.
  1674. plip= [PPT,NET] Parallel port network link
  1675. Format: { parport<nr> | timid | 0 }
  1676. See also Documentation/parport.txt.
  1677. pmtmr= [X86] Manual setup of pmtmr I/O Port.
  1678. Override pmtimer IOPort with a hex value.
  1679. e.g. pmtmr=0x508
  1680. pnp.debug [PNP]
  1681. Enable PNP debug messages. This depends on the
  1682. CONFIG_PNP_DEBUG_MESSAGES option.
  1683. pnpacpi= [ACPI]
  1684. { off }
  1685. pnpbios= [ISAPNP]
  1686. { on | off | curr | res | no-curr | no-res }
  1687. pnp_reserve_irq=
  1688. [ISAPNP] Exclude IRQs for the autoconfiguration
  1689. pnp_reserve_dma=
  1690. [ISAPNP] Exclude DMAs for the autoconfiguration
  1691. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1692. Ranges are in pairs (I/O port base and size).
  1693. pnp_reserve_mem=
  1694. [ISAPNP] Exclude memory regions for the
  1695. autoconfiguration.
  1696. Ranges are in pairs (memory base and size).
  1697. ports= [IP_VS_FTP] IPVS ftp helper module
  1698. Default is 21.
  1699. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  1700. may be specified.
  1701. Format: <port>,<port>....
  1702. print-fatal-signals=
  1703. [KNL] debug: print fatal signals
  1704. If enabled, warn about various signal handling
  1705. related application anomalies: too many signals,
  1706. too many POSIX.1 timers, fatal signals causing a
  1707. coredump - etc.
  1708. If you hit the warning due to signal overflow,
  1709. you might want to try "ulimit -i unlimited".
  1710. default: off.
  1711. printk.time= Show timing data prefixed to each printk message line
  1712. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1713. processor.max_cstate= [HW,ACPI]
  1714. Limit processor to maximum C-state
  1715. max_cstate=9 overrides any DMI blacklist limit.
  1716. processor.nocst [HW,ACPI]
  1717. Ignore the _CST method to determine C-states,
  1718. instead using the legacy FADT method
  1719. profile= [KNL] Enable kernel profiling via /proc/profile
  1720. Format: [schedule,]<number>
  1721. Param: "schedule" - profile schedule points.
  1722. Param: <number> - step/bucket size as a power of 2 for
  1723. statistical time based profiling.
  1724. Param: "sleep" - profile D-state sleeping (millisecs).
  1725. Requires CONFIG_SCHEDSTATS
  1726. Param: "kvm" - profile VM exits.
  1727. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1728. before loading.
  1729. See Documentation/blockdev/ramdisk.txt.
  1730. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1731. probe for; one of (bare|imps|exps|lifebook|any).
  1732. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1733. per second.
  1734. psmouse.resetafter= [HW,MOUSE]
  1735. Try to reset the device after so many bad packets
  1736. (0 = never).
  1737. psmouse.resolution=
  1738. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1739. psmouse.smartscroll=
  1740. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1741. 0 = disabled, 1 = enabled (default).
  1742. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1743. Format:
  1744. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1745. pt. [PARIDE]
  1746. See Documentation/blockdev/paride.txt.
  1747. pty.legacy_count=
  1748. [KNL] Number of legacy pty's. Overwrites compiled-in
  1749. default number.
  1750. quiet [KNL] Disable most log messages
  1751. r128= [HW,DRM]
  1752. raid= [HW,RAID]
  1753. See Documentation/md.txt.
  1754. ramdisk_blocksize= [RAM]
  1755. See Documentation/blockdev/ramdisk.txt.
  1756. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1757. See Documentation/blockdev/ramdisk.txt.
  1758. rcupdate.blimit= [KNL,BOOT]
  1759. Set maximum number of finished RCU callbacks to process
  1760. in one batch.
  1761. rcupdate.qhimark= [KNL,BOOT]
  1762. Set threshold of queued
  1763. RCU callbacks over which batch limiting is disabled.
  1764. rcupdate.qlowmark= [KNL,BOOT]
  1765. Set threshold of queued RCU callbacks below which
  1766. batch limiting is re-enabled.
  1767. rdinit= [KNL]
  1768. Format: <full_path>
  1769. Run specified binary instead of /init from the ramdisk,
  1770. used for early userspace startup. See initrd.
  1771. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1772. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1773. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1774. relax_domain_level=
  1775. [KNL, SMP] Set scheduler's default relax_domain_level.
  1776. See Documentation/cgroups/cpusets.txt.
  1777. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1778. reservetop= [X86-32]
  1779. Format: nn[KMG]
  1780. Reserves a hole at the top of the kernel virtual
  1781. address space.
  1782. reset_devices [KNL] Force drivers to reset the underlying device
  1783. during initialization.
  1784. resume= [SWSUSP]
  1785. Specify the partition device for software suspend
  1786. resume_offset= [SWSUSP]
  1787. Specify the offset from the beginning of the partition
  1788. given by "resume=" at which the swap header is located,
  1789. in <PAGE_SIZE> units (needed only for swap files).
  1790. See Documentation/power/swsusp-and-swap-files.txt
  1791. retain_initrd [RAM] Keep initrd memory after extraction
  1792. rhash_entries= [KNL,NET]
  1793. Set number of hash buckets for route cache
  1794. riscom8= [HW,SERIAL]
  1795. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1796. ro [KNL] Mount root device read-only on boot
  1797. root= [KNL] Root filesystem
  1798. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1799. mount the root filesystem
  1800. rootflags= [KNL] Set root filesystem mount option string
  1801. rootfstype= [KNL] Set root filesystem type
  1802. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1803. Useful for devices that are detected asynchronously
  1804. (e.g. USB and MMC devices).
  1805. rw [KNL] Mount root device read-write on boot
  1806. S [KNL] Run init in single mode
  1807. sa1100ir [NET]
  1808. See drivers/net/irda/sa1100_ir.c.
  1809. sbni= [NET] Granch SBNI12 leased line adapter
  1810. sched_debug [KNL] Enables verbose scheduler debug messages.
  1811. scsi_debug_*= [SCSI]
  1812. See drivers/scsi/scsi_debug.c.
  1813. scsi_default_dev_flags=
  1814. [SCSI] SCSI default device flags
  1815. Format: <integer>
  1816. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1817. Format: <vendor>:<model>:<flags>
  1818. (flags are integer value)
  1819. scsi_logging_level= [SCSI] a bit mask of logging levels
  1820. See drivers/scsi/scsi_logging.h for bits. Also
  1821. settable via sysctl at dev.scsi.logging_level
  1822. (/proc/sys/dev/scsi/logging_level).
  1823. There is also a nice 'scsi_logging_level' script in the
  1824. S390-tools package, available for download at
  1825. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1826. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1827. discovered. async scans them in kernel threads,
  1828. allowing boot to proceed. none ignores them, expecting
  1829. user space to do the scan.
  1830. security= [SECURITY] Choose a security module to enable at boot.
  1831. If this boot parameter is not specified, only the first
  1832. security module asking for security registration will be
  1833. loaded. An invalid security module name will be treated
  1834. as if no module has been chosen.
  1835. selinux= [SELINUX] Disable or enable SELinux at boot time.
  1836. Format: { "0" | "1" }
  1837. See security/selinux/Kconfig help text.
  1838. 0 -- disable.
  1839. 1 -- enable.
  1840. Default value is set via kernel config option.
  1841. If enabled at boot time, /selinux/disable can be used
  1842. later to disable prior to initial policy load.
  1843. apparmor= [APPARMOR] Disable or enable AppArmor at boot time
  1844. Format: { "0" | "1" }
  1845. See security/apparmor/Kconfig help text
  1846. 0 -- disable.
  1847. 1 -- enable.
  1848. Default value is set via kernel config option.
  1849. serialnumber [BUGS=X86-32]
  1850. shapers= [NET]
  1851. Maximal number of shapers.
  1852. show_msr= [x86] show boot-time MSR settings
  1853. Format: { <integer> }
  1854. Show boot-time (BIOS-initialized) MSR settings.
  1855. The parameter means the number of CPUs to show,
  1856. for example 1 means boot CPU only.
  1857. sim710= [SCSI,HW]
  1858. See header of drivers/scsi/sim710.c.
  1859. simeth= [IA-64]
  1860. simscsi=
  1861. slram= [HW,MTD]
  1862. slub_debug[=options[,slabs]] [MM, SLUB]
  1863. Enabling slub_debug allows one to determine the
  1864. culprit if slab objects become corrupted. Enabling
  1865. slub_debug can create guard zones around objects and
  1866. may poison objects when not in use. Also tracks the
  1867. last alloc / free. For more information see
  1868. Documentation/vm/slub.txt.
  1869. slub_max_order= [MM, SLUB]
  1870. Determines the maximum allowed order for slabs.
  1871. A high setting may cause OOMs due to memory
  1872. fragmentation. For more information see
  1873. Documentation/vm/slub.txt.
  1874. slub_min_objects= [MM, SLUB]
  1875. The minimum number of objects per slab. SLUB will
  1876. increase the slab order up to slub_max_order to
  1877. generate a sufficiently large slab able to contain
  1878. the number of objects indicated. The higher the number
  1879. of objects the smaller the overhead of tracking slabs
  1880. and the less frequently locks need to be acquired.
  1881. For more information see Documentation/vm/slub.txt.
  1882. slub_min_order= [MM, SLUB]
  1883. Determines the mininum page order for slabs. Must be
  1884. lower than slub_max_order.
  1885. For more information see Documentation/vm/slub.txt.
  1886. slub_nomerge [MM, SLUB]
  1887. Disable merging of slabs with similar size. May be
  1888. necessary if there is some reason to distinguish
  1889. allocs to different slabs. Debug options disable
  1890. merging on their own.
  1891. For more information see Documentation/vm/slub.txt.
  1892. smart2= [HW]
  1893. Format: <io1>[,<io2>[,...,<io8>]]
  1894. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1895. attempt to substitute SMP alternatives once at boot.
  1896. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1897. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1898. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1899. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1900. smsc-ircc2.ircc_irq= [HW] IRQ line
  1901. smsc-ircc2.ircc_dma= [HW] DMA channel
  1902. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1903. 0: Toshiba Satellite 1800 (GP data pin select)
  1904. 1: Fast pin select (default)
  1905. 2: ATC IRMode
  1906. snd-ad1816a= [HW,ALSA]
  1907. snd-ad1848= [HW,ALSA]
  1908. snd-ali5451= [HW,ALSA]
  1909. snd-als100= [HW,ALSA]
  1910. snd-als4000= [HW,ALSA]
  1911. snd-azt2320= [HW,ALSA]
  1912. snd-cmi8330= [HW,ALSA]
  1913. snd-cmipci= [HW,ALSA]
  1914. snd-cs4231= [HW,ALSA]
  1915. snd-cs4232= [HW,ALSA]
  1916. snd-cs4236= [HW,ALSA]
  1917. snd-cs4281= [HW,ALSA]
  1918. snd-cs46xx= [HW,ALSA]
  1919. snd-dt019x= [HW,ALSA]
  1920. snd-dummy= [HW,ALSA]
  1921. snd-emu10k1= [HW,ALSA]
  1922. snd-ens1370= [HW,ALSA]
  1923. snd-ens1371= [HW,ALSA]
  1924. snd-es968= [HW,ALSA]
  1925. snd-es1688= [HW,ALSA]
  1926. snd-es18xx= [HW,ALSA]
  1927. snd-es1938= [HW,ALSA]
  1928. snd-es1968= [HW,ALSA]
  1929. snd-fm801= [HW,ALSA]
  1930. snd-gusclassic= [HW,ALSA]
  1931. snd-gusextreme= [HW,ALSA]
  1932. snd-gusmax= [HW,ALSA]
  1933. snd-hdsp= [HW,ALSA]
  1934. snd-ice1712= [HW,ALSA]
  1935. snd-intel8x0= [HW,ALSA]
  1936. snd-interwave= [HW,ALSA]
  1937. snd-interwave-stb=
  1938. [HW,ALSA]
  1939. snd-korg1212= [HW,ALSA]
  1940. snd-maestro3= [HW,ALSA]
  1941. snd-mpu401= [HW,ALSA]
  1942. snd-mtpav= [HW,ALSA]
  1943. snd-nm256= [HW,ALSA]
  1944. snd-opl3sa2= [HW,ALSA]
  1945. snd-opti92x-ad1848=
  1946. [HW,ALSA]
  1947. snd-opti92x-cs4231=
  1948. [HW,ALSA]
  1949. snd-opti93x= [HW,ALSA]
  1950. snd-pmac= [HW,ALSA]
  1951. snd-rme32= [HW,ALSA]
  1952. snd-rme96= [HW,ALSA]
  1953. snd-rme9652= [HW,ALSA]
  1954. snd-sb8= [HW,ALSA]
  1955. snd-sb16= [HW,ALSA]
  1956. snd-sbawe= [HW,ALSA]
  1957. snd-serial= [HW,ALSA]
  1958. snd-sgalaxy= [HW,ALSA]
  1959. snd-sonicvibes= [HW,ALSA]
  1960. snd-sun-amd7930=
  1961. [HW,ALSA]
  1962. snd-sun-cs4231= [HW,ALSA]
  1963. snd-trident= [HW,ALSA]
  1964. snd-usb-audio= [HW,ALSA,USB]
  1965. snd-via82xx= [HW,ALSA]
  1966. snd-virmidi= [HW,ALSA]
  1967. snd-wavefront= [HW,ALSA]
  1968. snd-ymfpci= [HW,ALSA]
  1969. softlockup_panic=
  1970. [KNL] Should the soft-lockup detector generate panics.
  1971. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1972. See Documentation/sonypi.txt
  1973. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1974. See Documentation/serial/specialix.txt.
  1975. spia_io_base= [HW,MTD]
  1976. spia_fio_base=
  1977. spia_pedr=
  1978. spia_peddr=
  1979. sscape= [HW,OSS]
  1980. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1981. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1982. See Documentation/scsi/st.txt.
  1983. stacktrace [FTRACE]
  1984. Enabled the stack tracer on boot up.
  1985. sti= [PARISC,HW]
  1986. Format: <num>
  1987. Set the STI (builtin display/keyboard on the HP-PARISC
  1988. machines) console (graphic card) which should be used
  1989. as the initial boot-console.
  1990. See also comment in drivers/video/console/sticore.c.
  1991. sti_font= [HW]
  1992. See comment in drivers/video/console/sticore.c.
  1993. stifb= [HW]
  1994. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1995. sunrpc.min_resvport=
  1996. sunrpc.max_resvport=
  1997. [NFS,SUNRPC]
  1998. SunRPC servers often require that client requests
  1999. originate from a privileged port (i.e. a port in the
  2000. range 0 < portnr < 1024).
  2001. An administrator who wishes to reserve some of these
  2002. ports for other uses may adjust the range that the
  2003. kernel's sunrpc client considers to be privileged
  2004. using these two parameters to set the minimum and
  2005. maximum port values.
  2006. sunrpc.pool_mode=
  2007. [NFS]
  2008. Control how the NFS server code allocates CPUs to
  2009. service thread pools. Depending on how many NICs
  2010. you have and where their interrupts are bound, this
  2011. option will affect which CPUs will do NFS serving.
  2012. Note: this parameter cannot be changed while the
  2013. NFS server is running.
  2014. auto the server chooses an appropriate mode
  2015. automatically using heuristics
  2016. global a single global pool contains all CPUs
  2017. percpu one pool for each CPU
  2018. pernode one pool for each NUMA node (equivalent
  2019. to global on non-NUMA machines)
  2020. sunrpc.tcp_slot_table_entries=
  2021. sunrpc.udp_slot_table_entries=
  2022. [NFS,SUNRPC]
  2023. Sets the upper limit on the number of simultaneous
  2024. RPC calls that can be sent from the client to a
  2025. server. Increasing these values may allow you to
  2026. improve throughput, but will also increase the
  2027. amount of memory reserved for use by the client.
  2028. swiotlb= [IA-64] Number of I/O TLB slabs
  2029. switches= [HW,M68k]
  2030. sym53c416= [HW,SCSI]
  2031. See header of drivers/scsi/sym53c416.c.
  2032. sysrq_always_enabled
  2033. [KNL]
  2034. Ignore sysrq setting - this boot parameter will
  2035. neutralize any effect of /proc/sys/kernel/sysrq.
  2036. Useful for debugging.
  2037. t128= [HW,SCSI]
  2038. See header of drivers/scsi/t128.c.
  2039. tdfx= [HW,DRM]
  2040. test_suspend= [SUSPEND]
  2041. Specify "mem" (for Suspend-to-RAM) or "standby" (for
  2042. standby suspend) as the system sleep state to briefly
  2043. enter during system startup. The system is woken from
  2044. this state using a wakeup-capable RTC alarm.
  2045. thash_entries= [KNL,NET]
  2046. Set number of hash buckets for TCP connection
  2047. thermal.act= [HW,ACPI]
  2048. -1: disable all active trip points in all thermal zones
  2049. <degrees C>: override all lowest active trip points
  2050. thermal.crt= [HW,ACPI]
  2051. -1: disable all critical trip points in all thermal zones
  2052. <degrees C>: override all critical trip points
  2053. thermal.nocrt= [HW,ACPI]
  2054. Set to disable actions on ACPI thermal zone
  2055. critical and hot trip points.
  2056. thermal.off= [HW,ACPI]
  2057. 1: disable ACPI thermal control
  2058. thermal.psv= [HW,ACPI]
  2059. -1: disable all passive trip points
  2060. <degrees C>: override all passive trip points to this
  2061. value
  2062. thermal.tzp= [HW,ACPI]
  2063. Specify global default ACPI thermal zone polling rate
  2064. <deci-seconds>: poll all this frequency
  2065. 0: no polling (default)
  2066. tmscsim= [HW,SCSI]
  2067. See comment before function dc390_setup() in
  2068. drivers/scsi/tmscsim.c.
  2069. topology= [S390]
  2070. Format: {off | on}
  2071. Specify if the kernel should make use of the cpu
  2072. topology informations if the hardware supports these.
  2073. The scheduler will make use of these informations and
  2074. e.g. base its process migration decisions on it.
  2075. Default is off.
  2076. tp720= [HW,PS2]
  2077. tpm_suspend_pcr=[HW,TPM]
  2078. Format: integer pcr id
  2079. Specify that at suspend time, the tpm driver
  2080. should extend the specified pcr with zeros,
  2081. as a workaround for some chips which fail to
  2082. flush the last written pcr on TPM_SaveState.
  2083. This will guarantee that all the other pcrs
  2084. are saved.
  2085. trace_buf_size=nn[KMG]
  2086. [FTRACE] will set tracing buffer size.
  2087. trace_event=[event-list]
  2088. [FTRACE] Set and start specified trace events in order
  2089. to facilitate early boot debugging.
  2090. See also Documentation/trace/events.txt
  2091. trix= [HW,OSS] MediaTrix AudioTrix Pro
  2092. Format:
  2093. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  2094. tsc= Disable clocksource-must-verify flag for TSC.
  2095. Format: <string>
  2096. [x86] reliable: mark tsc clocksource as reliable, this
  2097. disables clocksource verification at runtime.
  2098. Used to enable high-resolution timer mode on older
  2099. hardware, and in virtualized environment.
  2100. turbografx.map[2|3]= [HW,JOY]
  2101. TurboGraFX parallel port interface
  2102. Format:
  2103. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  2104. See also Documentation/input/joystick-parport.txt
  2105. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  2106. See header of drivers/scsi/u14-34f.c.
  2107. uart401= [HW,OSS]
  2108. Format: <io>,<irq>
  2109. uart6850= [HW,OSS]
  2110. Format: <io>,<irq>
  2111. uhash_entries= [KNL,NET]
  2112. Set number of hash buckets for UDP/UDP-Lite connections
  2113. uhci-hcd.ignore_oc=
  2114. [USB] Ignore overcurrent events (default N).
  2115. Some badly-designed motherboards generate lots of
  2116. bogus events, for ports that aren't wired to
  2117. anything. Set this parameter to avoid log spamming.
  2118. Note that genuine overcurrent events won't be
  2119. reported either.
  2120. unknown_nmi_panic
  2121. [X86]
  2122. Set unknown_nmi_panic=1 early on boot.
  2123. usbcore.autosuspend=
  2124. [USB] The autosuspend time delay (in seconds) used
  2125. for newly-detected USB devices (default 2). This
  2126. is the time required before an idle device will be
  2127. autosuspended. Devices for which the delay is set
  2128. to a negative value won't be autosuspended at all.
  2129. usbcore.usbfs_snoop=
  2130. [USB] Set to log all usbfs traffic (default 0 = off).
  2131. usbcore.blinkenlights=
  2132. [USB] Set to cycle leds on hubs (default 0 = off).
  2133. usbcore.old_scheme_first=
  2134. [USB] Start with the old device initialization
  2135. scheme (default 0 = off).
  2136. usbcore.use_both_schemes=
  2137. [USB] Try the other device initialization scheme
  2138. if the first one fails (default 1 = enabled).
  2139. usbcore.initial_descriptor_timeout=
  2140. [USB] Specifies timeout for the initial 64-byte
  2141. USB_REQ_GET_DESCRIPTOR request in milliseconds
  2142. (default 5000 = 5.0 seconds).
  2143. usbhid.mousepoll=
  2144. [USBHID] The interval which mice are to be polled at.
  2145. usb-storage.delay_use=
  2146. [UMS] The delay in seconds before a new device is
  2147. scanned for Logical Units (default 5).
  2148. usb-storage.quirks=
  2149. [UMS] A list of quirks entries to supplement or
  2150. override the built-in unusual_devs list. List
  2151. entries are separated by commas. Each entry has
  2152. the form VID:PID:Flags where VID and PID are Vendor
  2153. and Product ID values (4-digit hex numbers) and
  2154. Flags is a set of characters, each corresponding
  2155. to a common usb-storage quirk flag as follows:
  2156. a = SANE_SENSE (collect more than 18 bytes
  2157. of sense data);
  2158. b = BAD_SENSE (don't collect more than 18
  2159. bytes of sense data);
  2160. c = FIX_CAPACITY (decrease the reported
  2161. device capacity by one sector);
  2162. h = CAPACITY_HEURISTICS (decrease the
  2163. reported device capacity by one
  2164. sector if the number is odd);
  2165. i = IGNORE_DEVICE (don't bind to this
  2166. device);
  2167. l = NOT_LOCKABLE (don't try to lock and
  2168. unlock ejectable media);
  2169. m = MAX_SECTORS_64 (don't transfer more
  2170. than 64 sectors = 32 KB at a time);
  2171. o = CAPACITY_OK (accept the capacity
  2172. reported by the device);
  2173. r = IGNORE_RESIDUE (the device reports
  2174. bogus residue values);
  2175. s = SINGLE_LUN (the device has only one
  2176. Logical Unit);
  2177. w = NO_WP_DETECT (don't test whether the
  2178. medium is write-protected).
  2179. Example: quirks=0419:aaf5:rl,0421:0433:rc
  2180. userpte=
  2181. [X86] Flags controlling user PTE allocations.
  2182. nohigh = do not allocate PTE pages in
  2183. HIGHMEM regardless of setting
  2184. of CONFIG_HIGHPTE.
  2185. vdso= [X86,SH]
  2186. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  2187. vdso=1: enable VDSO (default)
  2188. vdso=0: disable VDSO mapping
  2189. vdso32= [X86]
  2190. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  2191. vdso32=1: enable 32-bit VDSO (default)
  2192. vdso32=0: disable 32-bit VDSO mapping
  2193. vector= [IA-64,SMP]
  2194. vector=percpu: enable percpu vector domain
  2195. video= [FB] Frame buffer configuration
  2196. See Documentation/fb/modedb.txt.
  2197. vga= [BOOT,X86-32] Select a particular video mode
  2198. See Documentation/x86/boot.txt and
  2199. Documentation/svga.txt.
  2200. Use vga=ask for menu.
  2201. This is actually a boot loader parameter; the value is
  2202. passed to the kernel using a special protocol.
  2203. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  2204. size of <nn>. This can be used to increase the
  2205. minimum size (128MB on x86). It can also be used to
  2206. decrease the size and leave more room for directly
  2207. mapped kernel RAM.
  2208. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  2209. Format: <command>
  2210. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  2211. Format: <command>
  2212. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  2213. Format: <command>
  2214. vt.cur_default= [VT] Default cursor shape.
  2215. Format: 0xCCBBAA, where AA, BB, and CC are the same as
  2216. the parameters of the <Esc>[?A;B;Cc escape sequence;
  2217. see VGA-softcursor.txt. Default: 2 = underline.
  2218. vt.default_blu= [VT]
  2219. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  2220. Change the default blue palette of the console.
  2221. This is a 16-member array composed of values
  2222. ranging from 0-255.
  2223. vt.default_grn= [VT]
  2224. Format: <green0>,<green1>,<green2>,...,<green15>
  2225. Change the default green palette of the console.
  2226. This is a 16-member array composed of values
  2227. ranging from 0-255.
  2228. vt.default_red= [VT]
  2229. Format: <red0>,<red1>,<red2>,...,<red15>
  2230. Change the default red palette of the console.
  2231. This is a 16-member array composed of values
  2232. ranging from 0-255.
  2233. vt.default_utf8=
  2234. [VT]
  2235. Format=<0|1>
  2236. Set system-wide default UTF-8 mode for all tty's.
  2237. Default is 1, i.e. UTF-8 mode is enabled for all
  2238. newly opened terminals.
  2239. vt.global_cursor_default=
  2240. [VT]
  2241. Format=<-1|0|1>
  2242. Set system-wide default for whether a cursor
  2243. is shown on new VTs. Default is -1,
  2244. i.e. cursors will be created by default unless
  2245. overridden by individual drivers. 0 will hide
  2246. cursors, 1 will display them.
  2247. waveartist= [HW,OSS]
  2248. Format: <io>,<irq>,<dma>,<dma2>
  2249. wd33c93= [HW,SCSI]
  2250. See header of drivers/scsi/wd33c93.c.
  2251. wd7000= [HW,SCSI]
  2252. See header of drivers/scsi/wd7000.c.
  2253. watchdog timers [HW,WDT] For information on watchdog timers,
  2254. see Documentation/watchdog/watchdog-parameters.txt
  2255. or other driver-specific files in the
  2256. Documentation/watchdog/ directory.
  2257. x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
  2258. default x2apic cluster mode on platforms
  2259. supporting x2apic.
  2260. x86_mrst_timer= [X86-32,APBT]
  2261. Choose timer option for x86 Moorestown MID platform.
  2262. Two valid options are apbt timer only and lapic timer
  2263. plus one apbt timer for broadcast timer.
  2264. x86_mrst_timer=apbt_only | lapic_and_apbt
  2265. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  2266. xd_geo= See header of drivers/block/xd.c.
  2267. xirc2ps_cs= [NET,PCMCIA]
  2268. Format:
  2269. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  2270. ______________________________________________________________________
  2271. TODO:
  2272. Add documentation for ALSA options.
  2273. Add more DRM drivers.