kernel-parameters.txt 72 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878879880881882883884885886887888889890891892893894895896897898899900901902903904905906907908909910911912913914915916917918919920921922923924925926927928929930931932933934935936937938939940941942943944945946947948949950951952953954955956957958959960961962963964965966967968969970971972973974975976977978979980981982983984985986987988989990991992993994995996997998999100010011002100310041005100610071008100910101011101210131014101510161017101810191020102110221023102410251026102710281029103010311032103310341035103610371038103910401041104210431044104510461047104810491050105110521053105410551056105710581059106010611062106310641065106610671068106910701071107210731074107510761077107810791080108110821083108410851086108710881089109010911092109310941095109610971098109911001101110211031104110511061107110811091110111111121113111411151116111711181119112011211122112311241125112611271128112911301131113211331134113511361137113811391140114111421143114411451146114711481149115011511152115311541155115611571158115911601161116211631164116511661167116811691170117111721173117411751176117711781179118011811182118311841185118611871188118911901191119211931194119511961197119811991200120112021203120412051206120712081209121012111212121312141215121612171218121912201221122212231224122512261227122812291230123112321233123412351236123712381239124012411242124312441245124612471248124912501251125212531254125512561257125812591260126112621263126412651266126712681269127012711272127312741275127612771278127912801281128212831284128512861287128812891290129112921293129412951296129712981299130013011302130313041305130613071308130913101311131213131314131513161317131813191320132113221323132413251326132713281329133013311332133313341335133613371338133913401341134213431344134513461347134813491350135113521353135413551356135713581359136013611362136313641365136613671368136913701371137213731374137513761377137813791380138113821383138413851386138713881389139013911392139313941395139613971398139914001401140214031404140514061407140814091410141114121413141414151416141714181419142014211422142314241425142614271428142914301431143214331434143514361437143814391440144114421443144414451446144714481449145014511452145314541455145614571458145914601461146214631464146514661467146814691470147114721473147414751476147714781479148014811482148314841485148614871488148914901491149214931494149514961497149814991500150115021503150415051506150715081509151015111512151315141515151615171518151915201521152215231524152515261527152815291530153115321533153415351536153715381539154015411542154315441545154615471548154915501551155215531554155515561557155815591560156115621563156415651566156715681569157015711572157315741575157615771578157915801581158215831584158515861587158815891590159115921593159415951596159715981599160016011602160316041605160616071608160916101611161216131614161516161617161816191620162116221623162416251626162716281629163016311632163316341635163616371638163916401641164216431644164516461647164816491650165116521653165416551656165716581659166016611662166316641665166616671668166916701671167216731674167516761677167816791680168116821683168416851686168716881689169016911692169316941695169616971698169917001701170217031704170517061707170817091710171117121713171417151716171717181719172017211722172317241725172617271728172917301731173217331734173517361737173817391740174117421743174417451746174717481749175017511752175317541755175617571758175917601761176217631764176517661767176817691770177117721773177417751776177717781779178017811782178317841785178617871788178917901791179217931794179517961797179817991800180118021803180418051806180718081809181018111812181318141815181618171818181918201821182218231824182518261827182818291830183118321833183418351836183718381839184018411842184318441845184618471848184918501851185218531854185518561857185818591860186118621863186418651866186718681869187018711872187318741875187618771878187918801881188218831884188518861887188818891890189118921893189418951896189718981899190019011902190319041905190619071908190919101911191219131914191519161917191819191920192119221923192419251926192719281929193019311932193319341935193619371938193919401941194219431944194519461947194819491950195119521953195419551956195719581959196019611962196319641965196619671968196919701971197219731974197519761977197819791980198119821983198419851986198719881989199019911992199319941995199619971998199920002001200220032004200520062007200820092010201120122013201420152016201720182019202020212022202320242025202620272028202920302031203220332034203520362037203820392040204120422043204420452046204720482049205020512052205320542055205620572058205920602061206220632064206520662067206820692070207120722073207420752076207720782079208020812082208320842085208620872088208920902091209220932094209520962097209820992100210121022103210421052106210721082109211021112112211321142115211621172118211921202121212221232124212521262127212821292130213121322133213421352136213721382139214021412142214321442145214621472148214921502151215221532154215521562157215821592160216121622163216421652166216721682169217021712172217321742175217621772178217921802181218221832184218521862187218821892190219121922193219421952196219721982199220022012202220322042205220622072208220922102211221222132214221522162217221822192220222122222223222422252226222722282229223022312232223322342235223622372238223922402241224222432244224522462247224822492250225122522253225422552256225722582259226022612262226322642265226622672268226922702271227222732274227522762277227822792280228122822283228422852286228722882289229022912292229322942295229622972298229923002301230223032304230523062307230823092310231123122313
  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. This document may not be entirely up to date and comprehensive. The command
  15. "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
  16. module. Loadable modules, after being loaded into the running kernel, also
  17. reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
  18. parameters may be changed at runtime by the command
  19. "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
  20. The parameters listed below are only valid if certain kernel build options were
  21. enabled and if respective hardware is present. The text in square brackets at
  22. the beginning of each description states the restrictions within which a
  23. parameter is applicable:
  24. ACPI ACPI support is enabled.
  25. AGP AGP (Accelerated Graphics Port) is enabled.
  26. ALSA ALSA sound support is enabled.
  27. APIC APIC support is enabled.
  28. APM Advanced Power Management support is enabled.
  29. AVR32 AVR32 architecture is enabled.
  30. AX25 Appropriate AX.25 support is enabled.
  31. BLACKFIN Blackfin architecture is enabled.
  32. DRM Direct Rendering Management support is enabled.
  33. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
  34. EFI EFI Partitioning (GPT) is enabled
  35. EIDE EIDE/ATAPI support is enabled.
  36. FB The frame buffer device is enabled.
  37. HW Appropriate hardware is enabled.
  38. IA-64 IA-64 architecture is enabled.
  39. IOSCHED More than one I/O scheduler is enabled.
  40. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  41. ISAPNP ISA PnP code is enabled.
  42. ISDN Appropriate ISDN support is enabled.
  43. JOY Appropriate joystick support is enabled.
  44. LIBATA Libata driver is enabled
  45. LP Printer support is enabled.
  46. LOOP Loopback device support is enabled.
  47. M68k M68k architecture is enabled.
  48. These options have more detailed description inside of
  49. Documentation/m68k/kernel-options.txt.
  50. MCA MCA bus support is enabled.
  51. MDA MDA console support is enabled.
  52. MOUSE Appropriate mouse support is enabled.
  53. MSI Message Signaled Interrupts (PCI).
  54. MTD MTD (Memory Technology Device) support is enabled.
  55. NET Appropriate network support is enabled.
  56. NUMA NUMA support is enabled.
  57. GENERIC_TIME The generic timeofday code is enabled.
  58. NFS Appropriate NFS support is enabled.
  59. OSS OSS sound support is enabled.
  60. PV_OPS A paravirtualized kernel is enabled.
  61. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  62. PARISC The PA-RISC architecture is enabled.
  63. PCI PCI bus support is enabled.
  64. PCIE PCI Express support is enabled.
  65. PCMCIA The PCMCIA subsystem is enabled.
  66. PNP Plug & Play support is enabled.
  67. PPC PowerPC architecture is enabled.
  68. PPT Parallel port support is enabled.
  69. PS2 Appropriate PS/2 support is enabled.
  70. RAM RAM disk support is enabled.
  71. ROOTPLUG The example Root Plug LSM is enabled.
  72. S390 S390 architecture is enabled.
  73. SCSI Appropriate SCSI support is enabled.
  74. A lot of drivers has their options described inside of
  75. Documentation/scsi/.
  76. SECURITY Different security models are enabled.
  77. SELINUX SELinux support is enabled.
  78. SERIAL Serial support is enabled.
  79. SH SuperH architecture is enabled.
  80. SMP The kernel is an SMP kernel.
  81. SPARC Sparc architecture is enabled.
  82. SWSUSP Software suspend (hibernation) is enabled.
  83. SUSPEND System suspend states are enabled.
  84. TS Appropriate touchscreen support is enabled.
  85. USB USB support is enabled.
  86. USBHID USB Human Interface Device support is enabled.
  87. V4L Video For Linux support is enabled.
  88. VGA The VGA console has been enabled.
  89. VT Virtual terminal support is enabled.
  90. WDT Watchdog support is enabled.
  91. XT IBM PC/XT MFM hard disk support is enabled.
  92. X86-32 X86-32, aka i386 architecture is enabled.
  93. X86-64 X86-64 architecture is enabled.
  94. More X86-64 boot options can be found in
  95. Documentation/x86_64/boot-options.txt .
  96. In addition, the following text indicates that the option:
  97. BUGS= Relates to possible processor bugs on the said processor.
  98. KNL Is a kernel start-up parameter.
  99. BOOT Is a boot loader parameter.
  100. Parameters denoted with BOOT are actually interpreted by the boot
  101. loader, and have no meaning to the kernel directly.
  102. Do not modify the syntax of boot loader parameters without extreme
  103. need or coordination with <Documentation/i386/boot.txt>.
  104. There are also arch-specific kernel-parameters not documented here.
  105. See for example <Documentation/x86_64/boot-options.txt>.
  106. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  107. a trailing = on the name of any parameter states that that parameter will
  108. be entered as an environment variable, whereas its absence indicates that
  109. it will appear as a kernel argument readable via /proc/cmdline by programs
  110. running once the system is up.
  111. The number of kernel parameters is not limited, but the length of the
  112. complete command line (parameters including spaces etc.) is limited to
  113. a fixed number of characters. This limit depends on the architecture
  114. and is between 256 and 4096 characters. It is defined in the file
  115. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  116. acpi= [HW,ACPI,X86-64,i386]
  117. Advanced Configuration and Power Interface
  118. Format: { force | off | ht | strict | noirq }
  119. force -- enable ACPI if default was off
  120. off -- disable ACPI if default was on
  121. noirq -- do not use ACPI for IRQ routing
  122. ht -- run only enough ACPI to enable Hyper Threading
  123. strict -- Be less tolerant of platforms that are not
  124. strictly ACPI specification compliant.
  125. See also Documentation/power/pm.txt, pci=noacpi
  126. acpi_apic_instance= [ACPI, IOAPIC]
  127. Format: <int>
  128. 2: use 2nd APIC table, if available
  129. 1,0: use 1st APIC table
  130. default: 0
  131. acpi_sleep= [HW,ACPI] Sleep options
  132. Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
  133. See Documentation/power/video.txt for s3_bios and s3_mode.
  134. s3_beep is for debugging; it makes the PC's speaker beep
  135. as soon as the kernel's real-mode entry point is called.
  136. s4_nohwsig prevents ACPI hardware signature from being
  137. used during resume from hibernation.
  138. old_ordering causes the ACPI 1.0 ordering of the _PTS
  139. control method, wrt putting devices into low power
  140. states, to be enforced (the ACPI 2.0 ordering of _PTS is
  141. used by default).
  142. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  143. Format: { level | edge | high | low }
  144. acpi_irq_balance [HW,ACPI]
  145. ACPI will balance active IRQs
  146. default in APIC mode
  147. acpi_irq_nobalance [HW,ACPI]
  148. ACPI will not move active IRQs (default)
  149. default in PIC mode
  150. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  151. use by PCI
  152. Format: <irq>,<irq>...
  153. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  154. Format: <irq>,<irq>...
  155. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  156. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  157. Format: To spoof as Windows 98: ="Microsoft Windows"
  158. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  159. acpi_osi="string1" # add string1 -- only one string
  160. acpi_osi="!string2" # remove built-in string2
  161. acpi_osi= # disable all strings
  162. acpi_serialize [HW,ACPI] force serialization of AML methods
  163. acpi_skip_timer_override [HW,ACPI]
  164. Recognize and ignore IRQ0/pin2 Interrupt Override.
  165. For broken nForce2 BIOS resulting in XT-PIC timer.
  166. acpi_use_timer_override [HW,ACPI}
  167. Use timer override. For some broken Nvidia NF5 boards
  168. that require a timer override, but don't have
  169. HPET
  170. acpi.debug_layer= [HW,ACPI]
  171. Format: <int>
  172. Each bit of the <int> indicates an ACPI debug layer,
  173. 1: enable, 0: disable. It is useful for boot time
  174. debugging. After system has booted up, it can be set
  175. via /sys/module/acpi/parameters/debug_layer.
  176. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  177. Available bits (add the numbers together) to enable debug output
  178. for specific parts of the ACPI subsystem:
  179. 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
  180. 0x10 namespace 0x20 parser 0x40 dispatcher
  181. 0x80 executer 0x100 resources 0x200 acpica debugger
  182. 0x400 os services 0x800 acpica disassembler.
  183. The number can be in decimal or prefixed with 0x in hex.
  184. Warning: Many of these options can produce a lot of
  185. output and make your system unusable. Be very careful.
  186. acpi.debug_level= [HW,ACPI]
  187. Format: <int>
  188. Each bit of the <int> indicates an ACPI debug level,
  189. which corresponds to the level in an ACPI_DEBUG_PRINT
  190. statement. After system has booted up, this mask
  191. can be set via /sys/module/acpi/parameters/debug_level.
  192. CONFIG_ACPI_DEBUG must be enabled for this to produce
  193. any output. The number can be in decimal or prefixed
  194. with 0x in hex. Some of these options produce so much
  195. output that the system is unusable.
  196. The following global components are defined by the
  197. ACPI CA:
  198. 0x01 error
  199. 0x02 warn
  200. 0x04 init
  201. 0x08 debug object
  202. 0x10 info
  203. 0x20 init names
  204. 0x40 parse
  205. 0x80 load
  206. 0x100 dispatch
  207. 0x200 execute
  208. 0x400 names
  209. 0x800 operation region
  210. 0x1000 bfield
  211. 0x2000 tables
  212. 0x4000 values
  213. 0x8000 objects
  214. 0x10000 resources
  215. 0x20000 user requests
  216. 0x40000 package
  217. The number can be in decimal or prefixed with 0x in hex.
  218. Warning: Many of these options can produce a lot of
  219. output and make your system unusable. Be very careful.
  220. acpi.power_nocheck= [HW,ACPI]
  221. Format: 1/0 enable/disable the check of power state.
  222. On some bogus BIOS the _PSC object/_STA object of
  223. power resource can't return the correct device power
  224. state. In such case it is unneccessary to check its
  225. power state again in power transition.
  226. 1 : disable the power state check
  227. acpi_pm_good [X86-32,X86-64]
  228. Override the pmtimer bug detection: force the kernel
  229. to assume that this machine's pmtimer latches its value
  230. and always returns good values.
  231. agp= [AGP]
  232. { off | try_unsupported }
  233. off: disable AGP support
  234. try_unsupported: try to drive unsupported chipsets
  235. (may crash computer or cause data corruption)
  236. enable_timer_pin_1 [i386,x86-64]
  237. Enable PIN 1 of APIC timer
  238. Can be useful to work around chipset bugs
  239. (in particular on some ATI chipsets).
  240. The kernel tries to set a reasonable default.
  241. disable_timer_pin_1 [i386,x86-64]
  242. Disable PIN 1 of APIC timer
  243. Can be useful to work around chipset bugs.
  244. ad1848= [HW,OSS]
  245. Format: <io>,<irq>,<dma>,<dma2>,<type>
  246. advansys= [HW,SCSI]
  247. See header of drivers/scsi/advansys.c.
  248. advwdt= [HW,WDT] Advantech WDT
  249. Format: <iostart>,<iostop>
  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. aha152x= [HW,SCSI]
  254. See Documentation/scsi/aha152x.txt.
  255. aha1542= [HW,SCSI]
  256. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  257. aic7xxx= [HW,SCSI]
  258. See Documentation/scsi/aic7xxx.txt.
  259. aic79xx= [HW,SCSI]
  260. See Documentation/scsi/aic79xx.txt.
  261. amd_iommu= [HW,X86-84]
  262. Pass parameters to the AMD IOMMU driver in the system.
  263. Possible values are:
  264. isolate - enable device isolation (each device, as far
  265. as possible, will get its own protection
  266. domain)
  267. amd_iommu_size= [HW,X86-64]
  268. Define the size of the aperture for the AMD IOMMU
  269. driver. Possible values are:
  270. '32M', '64M' (default), '128M', '256M', '512M', '1G'
  271. amijoy.map= [HW,JOY] Amiga joystick support
  272. Map of devices attached to JOY0DAT and JOY1DAT
  273. Format: <a>,<b>
  274. See also Documentation/kernel/input/joystick.txt
  275. analog.map= [HW,JOY] Analog joystick and gamepad support
  276. Specifies type or capabilities of an analog joystick
  277. connected to one of 16 gameports
  278. Format: <type1>,<type2>,..<type16>
  279. apc= [HW,SPARC]
  280. Power management functions (SPARCstation-4/5 + deriv.)
  281. Format: noidle
  282. Disable APC CPU standby support. SPARCstation-Fox does
  283. not play well with APC CPU idle - disable it if you have
  284. APC and your system crashes randomly.
  285. apic= [APIC,i386] Advanced Programmable Interrupt Controller
  286. Change the output verbosity whilst booting
  287. Format: { quiet (default) | verbose | debug }
  288. Change the amount of debugging information output
  289. when initialising the APIC and IO-APIC components.
  290. apm= [APM] Advanced Power Management
  291. See header of arch/x86/kernel/apm_32.c.
  292. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  293. Format: <io>,<irq>,<nodeID>
  294. ataflop= [HW,M68k]
  295. atarimouse= [HW,MOUSE] Atari Mouse
  296. atascsi= [HW,SCSI] Atari SCSI
  297. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  298. EzKey and similar keyboards
  299. atkbd.reset= [HW] Reset keyboard during initialization
  300. atkbd.set= [HW] Select keyboard code set
  301. Format: <int> (2 = AT (default), 3 = PS/2)
  302. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  303. keyboards
  304. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  305. Format: <bool> (0 = real, 1 = synthetic (default))
  306. atkbd.softrepeat= [HW]
  307. Use software keyboard repeat
  308. autotest [IA64]
  309. baycom_epp= [HW,AX25]
  310. Format: <io>,<mode>
  311. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  312. Format: <io>,<mode>
  313. See header of drivers/net/hamradio/baycom_par.c.
  314. baycom_ser_fdx= [HW,AX25]
  315. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  316. Format: <io>,<irq>,<mode>[,<baud>]
  317. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  318. baycom_ser_hdx= [HW,AX25]
  319. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  320. Format: <io>,<irq>,<mode>
  321. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  322. boot_delay= Milliseconds to delay each printk during boot.
  323. Values larger than 10 seconds (10000) are changed to
  324. no delay (0).
  325. Format: integer
  326. bootmem_debug [KNL] Enable bootmem allocator debug messages.
  327. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  328. bttv.radio= Most important insmod options are available as
  329. kernel args too.
  330. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  331. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  332. BusLogic= [HW,SCSI]
  333. See drivers/scsi/BusLogic.c, comment before function
  334. BusLogic_ParseDriverOptions().
  335. c101= [NET] Moxa C101 synchronous serial card
  336. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  337. Sometimes CPU hardware bugs make them report the cache
  338. size incorrectly. The kernel will attempt work arounds
  339. to fix known problems, but for some CPUs it is not
  340. possible to determine what the correct size should be.
  341. This option provides an override for these situations.
  342. security= [SECURITY] Choose a security module to enable at boot.
  343. If this boot parameter is not specified, only the first
  344. security module asking for security registration will be
  345. loaded. An invalid security module name will be treated
  346. as if no module has been chosen.
  347. capability.disable=
  348. [SECURITY] Disable capabilities. This would normally
  349. be used only if an alternative security model is to be
  350. configured. Potentially dangerous and should only be
  351. used if you are entirely sure of the consequences.
  352. ccw_timeout_log [S390]
  353. See Documentation/s390/CommonIO for details.
  354. cgroup_disable= [KNL] Disable a particular controller
  355. Format: {name of the controller(s) to disable}
  356. {Currently supported controllers - "memory"}
  357. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  358. Format: { "0" | "1" }
  359. See security/selinux/Kconfig help text.
  360. 0 -- check protection applied by kernel (includes
  361. any implied execute protection).
  362. 1 -- check protection requested by application.
  363. Default value is set via a kernel config option.
  364. Value can be changed at runtime via
  365. /selinux/checkreqprot.
  366. cio_ignore= [S390]
  367. See Documentation/s390/CommonIO for details.
  368. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  369. [Deprecated]
  370. Forces specified clocksource (if available) to be used
  371. when calculating gettimeofday(). If specified
  372. clocksource is not available, it defaults to PIT.
  373. Format: { pit | tsc | cyclone | pmtmr }
  374. clocksource= [GENERIC_TIME] Override the default clocksource
  375. Format: <string>
  376. Override the default clocksource and use the clocksource
  377. with the name specified.
  378. Some clocksource names to choose from, depending on
  379. the platform:
  380. [all] jiffies (this is the base, fallback clocksource)
  381. [ACPI] acpi_pm
  382. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  383. pxa_timer,timer3,32k_counter,timer0_1
  384. [AVR32] avr32
  385. [X86-32] pit,hpet,tsc,vmi-timer;
  386. scx200_hrt on Geode; cyclone on IBM x440
  387. [MIPS] MIPS
  388. [PARISC] cr16
  389. [S390] tod
  390. [SH] SuperH
  391. [SPARC64] tick
  392. [X86-64] hpet,tsc
  393. clearcpuid=BITNUM [X86]
  394. Disable CPUID feature X for the kernel. See
  395. include/asm-x86/cpufeature.h for the valid bit numbers.
  396. Note the Linux specific bits are not necessarily
  397. stable over kernel options, but the vendor specific
  398. ones should be.
  399. Also note that user programs calling CPUID directly
  400. or using the feature without checking anything
  401. will still see it. This just prevents it from
  402. being used by the kernel or shown in /proc/cpuinfo.
  403. Also note the kernel might malfunction if you disable
  404. some critical bits.
  405. code_bytes [IA32/X86_64] How many bytes of object code to print
  406. in an oops report.
  407. Range: 0 - 8192
  408. Default: 64
  409. disable_8254_timer
  410. enable_8254_timer
  411. [IA32/X86_64] Disable/Enable interrupt 0 timer routing
  412. over the 8254 in addition to over the IO-APIC. The
  413. kernel tries to set a sensible default.
  414. hpet= [X86-32,HPET] option to control HPET usage
  415. Format: { enable (default) | disable | force }
  416. disable: disable HPET and use PIT instead
  417. force: allow force enabled of undocumented chips (ICH4,
  418. VIA, nVidia)
  419. com20020= [HW,NET] ARCnet - COM20020 chipset
  420. Format:
  421. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  422. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  423. Format: <io>[,<irq>]
  424. com90xx= [HW,NET]
  425. ARCnet - COM90xx chipset (memory-mapped buffers)
  426. Format: <io>[,<irq>[,<memstart>]]
  427. condev= [HW,S390] console device
  428. conmode=
  429. console= [KNL] Output console device and options.
  430. tty<n> Use the virtual console device <n>.
  431. ttyS<n>[,options]
  432. ttyUSB0[,options]
  433. Use the specified serial port. The options are of
  434. the form "bbbbpnf", where "bbbb" is the baud rate,
  435. "p" is parity ("n", "o", or "e"), "n" is number of
  436. bits, and "f" is flow control ("r" for RTS or
  437. omit it). Default is "9600n8".
  438. See Documentation/serial-console.txt for more
  439. information. See
  440. Documentation/networking/netconsole.txt for an
  441. alternative.
  442. uart[8250],io,<addr>[,options]
  443. uart[8250],mmio,<addr>[,options]
  444. Start an early, polled-mode console on the 8250/16550
  445. UART at the specified I/O port or MMIO address,
  446. switching to the matching ttyS device later. The
  447. options are the same as for ttyS, above.
  448. If the device connected to the port is not a TTY but a braille
  449. device, prepend "brl," before the device type, for instance
  450. console=brl,ttyS0
  451. For now, only VisioBraille is supported.
  452. earlycon= [KNL] Output early console device and options.
  453. uart[8250],io,<addr>[,options]
  454. uart[8250],mmio,<addr>[,options]
  455. Start an early, polled-mode console on the 8250/16550
  456. UART at the specified I/O port or MMIO address.
  457. The options are the same as for ttyS, above.
  458. no_console_suspend
  459. [HW] Never suspend the console
  460. Disable suspending of consoles during suspend and
  461. hibernate operations. Once disabled, debugging
  462. messages can reach various consoles while the rest
  463. of the system is being put to sleep (ie, while
  464. debugging driver suspend/resume hooks). This may
  465. not work reliably with all consoles, but is known
  466. to work with serial and VGA consoles.
  467. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  468. Format:
  469. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  470. crashkernel=nn[KMG]@ss[KMG]
  471. [KNL] Reserve a chunk of physical memory to
  472. hold a kernel to switch to with kexec on panic.
  473. crashkernel=range1:size1[,range2:size2,...][@offset]
  474. [KNL] Same as above, but depends on the memory
  475. in the running system. The syntax of range is
  476. start-[end] where start and end are both
  477. a memory unit (amount[KMG]). See also
  478. Documentation/kdump/kdump.txt for a example.
  479. cs4232= [HW,OSS]
  480. Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
  481. cs89x0_dma= [HW,NET]
  482. Format: <dma>
  483. cs89x0_media= [HW,NET]
  484. Format: { rj45 | aui | bnc }
  485. dasd= [HW,NET]
  486. See header of drivers/s390/block/dasd_devmap.c.
  487. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  488. (one device per port)
  489. Format: <port#>,<type>
  490. See also Documentation/input/joystick-parport.txt
  491. debug [KNL] Enable kernel debugging (events log level).
  492. debug_locks_verbose=
  493. [KNL] verbose self-tests
  494. Format=<0|1>
  495. Print debugging info while doing the locking API
  496. self-tests.
  497. We default to 0 (no extra messages), setting it to
  498. 1 will print _a lot_ more information - normally
  499. only useful to kernel developers.
  500. debug_objects [KNL] Enable object debugging
  501. debugpat [X86] Enable PAT debugging
  502. decnet.addr= [HW,NET]
  503. Format: <area>[,<node>]
  504. See also Documentation/networking/decnet.txt.
  505. vt.default_blu= [VT]
  506. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  507. Change the default blue palette of the console.
  508. This is a 16-member array composed of values
  509. ranging from 0-255.
  510. vt.default_grn= [VT]
  511. Format: <green0>,<green1>,<green2>,...,<green15>
  512. Change the default green palette of the console.
  513. This is a 16-member array composed of values
  514. ranging from 0-255.
  515. vt.default_red= [VT]
  516. Format: <red0>,<red1>,<red2>,...,<red15>
  517. Change the default red palette of the console.
  518. This is a 16-member array composed of values
  519. ranging from 0-255.
  520. vt.default_utf8=
  521. [VT]
  522. Format=<0|1>
  523. Set system-wide default UTF-8 mode for all tty's.
  524. Default is 1, i.e. UTF-8 mode is enabled for all
  525. newly opened terminals.
  526. dhash_entries= [KNL]
  527. Set number of hash buckets for dentry cache.
  528. digi= [HW,SERIAL]
  529. IO parameters + enable/disable command.
  530. digiepca= [HW,SERIAL]
  531. See drivers/char/README.epca and
  532. Documentation/digiepca.txt.
  533. disable_mtrr_cleanup [X86]
  534. enable_mtrr_cleanup [X86]
  535. The kernel tries to adjust MTRR layout from continuous
  536. to discrete, to make X server driver able to add WB
  537. entry later. This parameter enables/disables that.
  538. mtrr_chunk_size=nn[KMG] [X86]
  539. used for mtrr cleanup. It is largest continous chunk
  540. that could hold holes aka. UC entries.
  541. mtrr_gran_size=nn[KMG] [X86]
  542. Used for mtrr cleanup. It is granularity of mtrr block.
  543. Default is 1.
  544. Large value could prevent small alignment from
  545. using up MTRRs.
  546. mtrr_spare_reg_nr=n [X86]
  547. Format: <integer>
  548. Range: 0,7 : spare reg number
  549. Default : 1
  550. Used for mtrr cleanup. It is spare mtrr entries number.
  551. Set to 2 or more if your graphical card needs more.
  552. disable_mtrr_trim [X86, Intel and AMD only]
  553. By default the kernel will trim any uncacheable
  554. memory out of your available memory pool based on
  555. MTRR settings. This parameter disables that behavior,
  556. possibly causing your machine to run very slowly.
  557. dmasound= [HW,OSS] Sound subsystem buffers
  558. dscc4.setup= [NET]
  559. dtc3181e= [HW,SCSI]
  560. earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
  561. earlyprintk=vga
  562. earlyprintk=serial[,ttySn[,baudrate]]
  563. Append ",keep" to not disable it when the real console
  564. takes over.
  565. Only vga or serial at a time, not both.
  566. Currently only ttyS0 and ttyS1 are supported.
  567. Interaction with the standard serial driver is not
  568. very good.
  569. The VGA output is eventually overwritten by the real
  570. console.
  571. eata= [HW,SCSI]
  572. edd= [EDD]
  573. Format: {"off" | "on" | "skip[mbr]"}
  574. eisa_irq_edge= [PARISC,HW]
  575. See header of drivers/parisc/eisa.c.
  576. elanfreq= [X86-32]
  577. See comment before function elanfreq_setup() in
  578. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
  579. elevator= [IOSCHED]
  580. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  581. See Documentation/block/as-iosched.txt and
  582. Documentation/block/deadline-iosched.txt for details.
  583. elfcorehdr= [X86-32, X86_64]
  584. Specifies physical address of start of kernel core
  585. image elf header. Generally kexec loader will
  586. pass this option to capture kernel.
  587. See Documentation/kdump/kdump.txt for details.
  588. enforcing [SELINUX] Set initial enforcing status.
  589. Format: {"0" | "1"}
  590. See security/selinux/Kconfig help text.
  591. 0 -- permissive (log only, no denials).
  592. 1 -- enforcing (deny and log).
  593. Default value is 0.
  594. Value can be changed at runtime via /selinux/enforce.
  595. es1371= [HW,OSS]
  596. Format: <spdif>,[<nomix>,[<amplifier>]]
  597. See also header of sound/oss/es1371.c.
  598. ether= [HW,NET] Ethernet cards parameters
  599. This option is obsoleted by the "netdev=" option, which
  600. has equivalent usage. See its documentation for details.
  601. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  602. Format: <io>[,<irq>]
  603. failslab=
  604. fail_page_alloc=
  605. fail_make_request=[KNL]
  606. General fault injection mechanism.
  607. Format: <interval>,<probability>,<space>,<times>
  608. See also /Documentation/fault-injection/.
  609. fd_mcs= [HW,SCSI]
  610. See header of drivers/scsi/fd_mcs.c.
  611. fdomain= [HW,SCSI]
  612. See header of drivers/scsi/fdomain.c.
  613. floppy= [HW]
  614. See Documentation/floppy.txt.
  615. force_pal_cache_flush
  616. [IA-64] Avoid check_sal_cache_flush which may hang on
  617. buggy SAL_CACHE_FLUSH implementations. Using this
  618. parameter will force ia64_sal_cache_flush to call
  619. ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
  620. gamecon.map[2|3]=
  621. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  622. support via parallel port (up to 5 devices per port)
  623. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  624. See also Documentation/input/joystick-parport.txt
  625. gamma= [HW,DRM]
  626. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  627. Format: off | on
  628. default: on
  629. gdth= [HW,SCSI]
  630. See header of drivers/scsi/gdth.c.
  631. gpt [EFI] Forces disk with valid GPT signature but
  632. invalid Protective MBR to be treated as GPT.
  633. gvp11= [HW,SCSI]
  634. hashdist= [KNL,NUMA] Large hashes allocated during boot
  635. are distributed across NUMA nodes. Defaults on
  636. for IA-64, off otherwise.
  637. Format: 0 | 1 (for off | on)
  638. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  639. hd= [EIDE] (E)IDE hard drive subsystem geometry
  640. Format: <cyl>,<head>,<sect>
  641. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  642. size of <nn>. This works even on boxes that have no
  643. highmem otherwise. This also works to reduce highmem
  644. size on bigger boxes.
  645. highres= [KNL] Enable/disable high resolution timer mode.
  646. Valid parameters: "on", "off"
  647. Default: "on"
  648. hisax= [HW,ISDN]
  649. See Documentation/isdn/README.HiSax.
  650. hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
  651. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
  652. On x86-64 and powerpc, this option can be specified
  653. multiple times interleaved with hugepages= to reserve
  654. huge pages of different sizes. Valid pages sizes on
  655. x86-64 are 2M (when the CPU supports "pse") and 1G
  656. (when the CPU supports the "pdpe1gb" cpuinfo flag)
  657. Note that 1GB pages can only be allocated at boot time
  658. using hugepages= and not freed afterwards.
  659. default_hugepagesz=
  660. [same as hugepagesz=] The size of the default
  661. HugeTLB page size. This is the size represented by
  662. the legacy /proc/ hugepages APIs, used for SHM, and
  663. default size when mounting hugetlbfs filesystems.
  664. Defaults to the default architecture's huge page size
  665. if not specified.
  666. i8042.direct [HW] Put keyboard port into non-translated mode
  667. i8042.dumbkbd [HW] Pretend that controller can only read data from
  668. keyboard and cannot control its state
  669. (Don't attempt to blink the leds)
  670. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  671. i8042.nokbd [HW] Don't check/create keyboard port
  672. i8042.noloop [HW] Disable the AUX Loopback command while probing
  673. for the AUX port
  674. i8042.nomux [HW] Don't check presence of an active multiplexing
  675. controller
  676. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  677. controllers
  678. i8042.panicblink=
  679. [HW] Frequency with which keyboard LEDs should blink
  680. when kernel panics (default is 0.5 sec)
  681. i8042.reset [HW] Reset the controller during init and cleanup
  682. i8042.unlock [HW] Unlock (ignore) the keylock
  683. i810= [HW,DRM]
  684. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  685. indicates that the driver is running on unsupported
  686. hardware.
  687. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  688. does not match list of supported models.
  689. i8k.power_status
  690. [HW] Report power status in /proc/i8k
  691. (disabled by default)
  692. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  693. capability is set.
  694. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  695. See Documentation/mca.txt.
  696. icn= [HW,ISDN]
  697. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  698. ide= [HW] (E)IDE subsystem
  699. Format: ide=nodma or ide=doubler
  700. See Documentation/ide/ide.txt.
  701. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  702. See Documentation/ide/ide.txt.
  703. idle= [X86]
  704. Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
  705. Poll forces a polling idle loop that can slightly improves the performance
  706. of waking up a idle CPU, but will use a lot of power and make the system
  707. run hot. Not recommended.
  708. idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
  709. to not use it because it doesn't save as much power as a normal idle
  710. loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
  711. as idle=poll.
  712. idle=halt. Halt is forced to be used for CPU idle.
  713. In such case C2/C3 won't be used again.
  714. idle=nomwait. Disable mwait for CPU C-states
  715. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  716. Claim all unknown PCI IDE storage controllers.
  717. ignore_loglevel [KNL]
  718. Ignore loglevel setting - this will print /all/
  719. kernel messages to the console. Useful for debugging.
  720. ihash_entries= [KNL]
  721. Set number of hash buckets for inode cache.
  722. in2000= [HW,SCSI]
  723. See header of drivers/scsi/in2000.c.
  724. init= [KNL]
  725. Format: <full_path>
  726. Run specified binary instead of /sbin/init as init
  727. process.
  728. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  729. for working out where the kernel is dying during
  730. startup.
  731. initrd= [BOOT] Specify the location of the initial ramdisk
  732. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  733. Format: <irq>
  734. inttest= [IA64]
  735. iommu= [x86]
  736. off
  737. force
  738. noforce
  739. biomerge
  740. panic
  741. nopanic
  742. merge
  743. nomerge
  744. forcesac
  745. soft
  746. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  747. off
  748. Disable intel iommu driver.
  749. igfx_off [Default Off]
  750. By default, gfx is mapped as normal device. If a gfx
  751. device has a dedicated DMAR unit, the DMAR unit is
  752. bypassed by not enabling DMAR with this option. In
  753. this case, gfx device will use physical address for
  754. DMA.
  755. forcedac [x86_64]
  756. With this option iommu will not optimize to look
  757. for io virtual address below 32 bit forcing dual
  758. address cycle on pci bus for cards supporting greater
  759. than 32 bit addressing. The default is to look
  760. for translation below 32 bit and if not available
  761. then look in the higher range.
  762. strict [Default Off]
  763. With this option on every unmap_single operation will
  764. result in a hardware IOTLB flush operation as opposed
  765. to batching them for performance.
  766. io_delay= [X86-32,X86-64] I/O delay method
  767. 0x80
  768. Standard port 0x80 based delay
  769. 0xed
  770. Alternate port 0xed based delay (needed on some systems)
  771. udelay
  772. Simple two microseconds delay
  773. none
  774. No delay
  775. io7= [HW] IO7 for Marvel based alpha systems
  776. See comment before marvel_specify_io7 in
  777. arch/alpha/kernel/core_marvel.c.
  778. ip= [IP_PNP]
  779. See Documentation/filesystems/nfsroot.txt.
  780. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  781. See comment before ip2_setup() in
  782. drivers/char/ip2/ip2base.c.
  783. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  784. See header of drivers/scsi/ips.c.
  785. ports= [IP_VS_FTP] IPVS ftp helper module
  786. Default is 21.
  787. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  788. may be specified.
  789. Format: <port>,<port>....
  790. irqfixup [HW]
  791. When an interrupt is not handled search all handlers
  792. for it. Intended to get systems with badly broken
  793. firmware running.
  794. irqpoll [HW]
  795. When an interrupt is not handled search all handlers
  796. for it. Also check all handlers each timer
  797. interrupt. Intended to get systems with badly broken
  798. firmware running.
  799. isapnp= [ISAPNP]
  800. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  801. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  802. Format:
  803. <cpu number>,...,<cpu number>
  804. or
  805. <cpu number>-<cpu number> (must be a positive range in ascending order)
  806. or a mixture
  807. <cpu number>,...,<cpu number>-<cpu number>
  808. This option can be used to specify one or more CPUs
  809. to isolate from the general SMP balancing and scheduling
  810. algorithms. The only way to move a process onto or off
  811. an "isolated" CPU is via the CPU affinity syscalls.
  812. <cpu number> begins at 0 and the maximum value is
  813. "number of CPUs in system - 1".
  814. This option is the preferred way to isolate CPUs. The
  815. alternative -- manually setting the CPU mask of all
  816. tasks in the system -- can cause problems and
  817. suboptimal load balancer performance.
  818. iucv= [HW,NET]
  819. js= [HW,JOY] Analog joystick
  820. See Documentation/input/joystick.txt.
  821. kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  822. specifies the amount of memory usable by the kernel
  823. for non-movable allocations. The requested amount is
  824. spread evenly throughout all nodes in the system. The
  825. remaining memory in each node is used for Movable
  826. pages. In the event, a node is too small to have both
  827. kernelcore and Movable pages, kernelcore pages will
  828. take priority and other nodes will have a larger number
  829. of kernelcore pages. The Movable zone is used for the
  830. allocation of pages that may be reclaimed or moved
  831. by the page migration subsystem. This means that
  832. HugeTLB pages may not be allocated from this zone.
  833. Note that allocations like PTEs-from-HighMem still
  834. use the HighMem zone if it exists, and the Normal
  835. zone if it does not.
  836. movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  837. is similar to kernelcore except it specifies the
  838. amount of memory used for migratable allocations.
  839. If both kernelcore and movablecore is specified,
  840. then kernelcore will be at *least* the specified
  841. value but may be more. If movablecore on its own
  842. is specified, the administrator must be careful
  843. that the amount of memory usable for all allocations
  844. is not too small.
  845. keepinitrd [HW,ARM]
  846. kstack=N [X86-32,X86-64] Print N words from the kernel stack
  847. in oops dumps.
  848. kgdboc= [HW] kgdb over consoles.
  849. Requires a tty driver that supports console polling.
  850. (only serial suported for now)
  851. Format: <serial_device>[,baud]
  852. l2cr= [PPC]
  853. l3cr= [PPC]
  854. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  855. disabled it.
  856. lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
  857. C2 power state.
  858. libata.dma= [LIBATA] DMA control
  859. libata.dma=0 Disable all PATA and SATA DMA
  860. libata.dma=1 PATA and SATA Disk DMA only
  861. libata.dma=2 ATAPI (CDROM) DMA only
  862. libata.dma=4 Compact Flash DMA only
  863. Combinations also work, so libata.dma=3 enables DMA
  864. for disks and CDROMs, but not CFs.
  865. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  866. when set.
  867. Format: <int>
  868. libata.force= [LIBATA] Force configurations. The format is comma
  869. separated list of "[ID:]VAL" where ID is
  870. PORT[:DEVICE]. PORT and DEVICE are decimal numbers
  871. matching port, link or device. Basically, it matches
  872. the ATA ID string printed on console by libata. If
  873. the whole ID part is omitted, the last PORT and DEVICE
  874. values are used. If ID hasn't been specified yet, the
  875. configuration applies to all ports, links and devices.
  876. If only DEVICE is omitted, the parameter applies to
  877. the port and all links and devices behind it. DEVICE
  878. number of 0 either selects the first device or the
  879. first fan-out link behind PMP device. It does not
  880. select the host link. DEVICE number of 15 selects the
  881. host link and device attached to it.
  882. The VAL specifies the configuration to force. As long
  883. as there's no ambiguity shortcut notation is allowed.
  884. For example, both 1.5 and 1.5G would work for 1.5Gbps.
  885. The following configurations can be forced.
  886. * Cable type: 40c, 80c, short40c, unk, ign or sata.
  887. Any ID with matching PORT is used.
  888. * SATA link speed limit: 1.5Gbps or 3.0Gbps.
  889. * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
  890. udma[/][16,25,33,44,66,100,133] notation is also
  891. allowed.
  892. * [no]ncq: Turn on or off NCQ.
  893. * nohrst, nosrst, norst: suppress hard, soft
  894. and both resets.
  895. If there are multiple matching configurations changing
  896. the same attribute, the last one is used.
  897. load_ramdisk= [RAM] List of ramdisks to load from floppy
  898. See Documentation/ramdisk.txt.
  899. lockd.nlm_grace_period=P [NFS] Assign grace period.
  900. Format: <integer>
  901. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  902. Format: <integer>
  903. lockd.nlm_timeout=T [NFS] Assign timeout value.
  904. Format: <integer>
  905. lockd.nlm_udpport=M [NFS] Assign UDP port.
  906. Format: <integer>
  907. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  908. Format: <irq>
  909. loglevel= All Kernel Messages with a loglevel smaller than the
  910. console loglevel will be printed to the console. It can
  911. also be changed with klogd or other programs. The
  912. loglevels are defined as follows:
  913. 0 (KERN_EMERG) system is unusable
  914. 1 (KERN_ALERT) action must be taken immediately
  915. 2 (KERN_CRIT) critical conditions
  916. 3 (KERN_ERR) error conditions
  917. 4 (KERN_WARNING) warning conditions
  918. 5 (KERN_NOTICE) normal but significant condition
  919. 6 (KERN_INFO) informational
  920. 7 (KERN_DEBUG) debug-level messages
  921. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  922. Format: { n | nk | nM }
  923. n must be a power of two. The default size
  924. is set in the kernel config file.
  925. logo.nologo [FB] Disables display of the built-in Linux logo.
  926. This may be used to provide more screen space for
  927. kernel log messages and is useful when debugging
  928. kernel boot problems.
  929. lp=0 [LP] Specify parallel ports to use, e.g,
  930. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  931. lp=reset first parallel port). 'lp=0' disables the
  932. lp=auto printer driver. 'lp=reset' (which can be
  933. specified in addition to the ports) causes
  934. attached printers to be reset. Using
  935. lp=port1,port2,... specifies the parallel ports
  936. to associate lp devices with, starting with
  937. lp0. A port specification may be 'none' to skip
  938. that lp device, or a parport name such as
  939. 'parport0'. Specifying 'lp=auto' instead of a
  940. port specification list means that device IDs
  941. from each port should be examined, to see if
  942. an IEEE 1284-compliant printer is attached; if
  943. so, the driver will manage that printer.
  944. See also header of drivers/char/lp.c.
  945. lpj=n [KNL]
  946. Sets loops_per_jiffy to given constant, thus avoiding
  947. time-consuming boot-time autodetection (up to 250 ms per
  948. CPU). 0 enables autodetection (default). To determine
  949. the correct value for your kernel, boot with normal
  950. autodetection and see what value is printed. Note that
  951. on SMP systems the preset will be applied to all CPUs,
  952. which is likely to cause problems if your CPUs need
  953. significantly divergent settings. An incorrect value
  954. will cause delays in the kernel to be wrong, leading to
  955. unpredictable I/O errors and other breakage. Although
  956. unlikely, in the extreme case this might damage your
  957. hardware.
  958. ltpc= [NET]
  959. Format: <io>,<irq>,<dma>
  960. mac5380= [HW,SCSI] Format:
  961. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  962. machvec= [IA64] Force the use of a particular machine-vector
  963. (machvec) in a generic kernel.
  964. Example: machvec=hpzx1_swiotlb
  965. max_loop= [LOOP] Maximum number of loopback devices that can
  966. be mounted
  967. Format: <1-256>
  968. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  969. should make use of. maxcpus=n : n >= 0 limits the
  970. kernel to using 'n' processors. n=0 is a special case,
  971. it is equivalent to "nosmp", which also disables
  972. the IO APIC.
  973. max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
  974. equal to this physical address is ignored.
  975. max_luns= [SCSI] Maximum number of LUNs to probe.
  976. Should be between 1 and 2^32-1.
  977. max_report_luns=
  978. [SCSI] Maximum number of LUNs received.
  979. Should be between 1 and 16384.
  980. mcatest= [IA-64]
  981. mce [X86-32] Machine Check Exception
  982. mce=option [X86-64] See Documentation/x86_64/boot-options.txt
  983. md= [HW] RAID subsystems devices and level
  984. See Documentation/md.txt.
  985. mdacon= [MDA]
  986. Format: <first>,<last>
  987. Specifies range of consoles to be captured by the MDA.
  988. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  989. Amount of memory to be used when the kernel is not able
  990. to see the whole system memory or for test.
  991. [X86-32] Use together with memmap= to avoid physical
  992. address space collisions. Without memmap= PCI devices
  993. could be placed at addresses belonging to unused RAM.
  994. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  995. memory.
  996. memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
  997. E820 memory map, as specified by the user.
  998. Such memmap=exactmap lines can be constructed based on
  999. BIOS output or other requirements. See the memmap=nn@ss
  1000. option description.
  1001. memmap=nn[KMG]@ss[KMG]
  1002. [KNL] Force usage of a specific region of memory
  1003. Region of memory to be used, from ss to ss+nn.
  1004. memmap=nn[KMG]#ss[KMG]
  1005. [KNL,ACPI] Mark specific memory as ACPI data.
  1006. Region of memory to be used, from ss to ss+nn.
  1007. memmap=nn[KMG]$ss[KMG]
  1008. [KNL,ACPI] Mark specific memory as reserved.
  1009. Region of memory to be used, from ss to ss+nn.
  1010. Example: Exclude memory from 0x18690000-0x1869ffff
  1011. memmap=64K$0x18690000
  1012. or
  1013. memmap=0x10000$0x18690000
  1014. memtest= [KNL,X86] Enable memtest
  1015. Format: <integer>
  1016. range: 0,4 : pattern number
  1017. default : 0 <disable>
  1018. meye.*= [HW] Set MotionEye Camera parameters
  1019. See Documentation/video4linux/meye.txt.
  1020. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  1021. Multi-Function General Purpose Timers on AMD Geode
  1022. platforms.
  1023. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  1024. the BIOS has incorrectly applied a workaround. TinyBIOS
  1025. version 0.98 is known to be affected, 0.99 fixes the
  1026. problem by letting the user disable the workaround.
  1027. mga= [HW,DRM]
  1028. mminit_loglevel=
  1029. [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
  1030. parameter allows control of the logging verbosity for
  1031. the additional memory initialisation checks. A value
  1032. of 0 disables mminit logging and a level of 4 will
  1033. log everything. Information is printed at KERN_DEBUG
  1034. so loglevel=8 may also need to be specified.
  1035. mousedev.tap_time=
  1036. [MOUSE] Maximum time between finger touching and
  1037. leaving touchpad surface for touch to be considered
  1038. a tap and be reported as a left button click (for
  1039. touchpads working in absolute mode only).
  1040. Format: <msecs>
  1041. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  1042. reporting absolute coordinates, such as tablets
  1043. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  1044. reporting absolute coordinates, such as tablets
  1045. mpu401= [HW,OSS]
  1046. Format: <io>,<irq>
  1047. MTD_Partition= [MTD]
  1048. Format: <name>,<region-number>,<size>,<offset>
  1049. MTD_Region= [MTD] Format:
  1050. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  1051. mtdparts= [MTD]
  1052. See drivers/mtd/cmdlinepart.c.
  1053. mtdset= [ARM]
  1054. ARM/S3C2412 JIVE boot control
  1055. See arch/arm/mach-s3c2412/mach-jive.c
  1056. mtouchusb.raw_coordinates=
  1057. [HW] Make the MicroTouch USB driver use raw coordinates
  1058. ('y', default) or cooked coordinates ('n')
  1059. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  1060. NCR_D700= [HW,SCSI]
  1061. See header of drivers/scsi/NCR_D700.c.
  1062. ncr5380= [HW,SCSI]
  1063. ncr53c400= [HW,SCSI]
  1064. ncr53c400a= [HW,SCSI]
  1065. ncr53c406a= [HW,SCSI]
  1066. ncr53c8xx= [HW,SCSI]
  1067. netdev= [NET] Network devices parameters
  1068. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  1069. Note that mem_start is often overloaded to mean
  1070. something different and driver-specific.
  1071. This usage is only documented in each driver source
  1072. file if at all.
  1073. nf_conntrack.acct=
  1074. [NETFILTER] Enable connection tracking flow accounting
  1075. 0 to disable accounting
  1076. 1 to enable accounting
  1077. Default value depends on CONFIG_NF_CT_ACCT that is
  1078. going to be removed in 2.6.29.
  1079. nfsaddrs= [NFS]
  1080. See Documentation/filesystems/nfsroot.txt.
  1081. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  1082. See Documentation/filesystems/nfsroot.txt.
  1083. nfs.callback_tcpport=
  1084. [NFS] set the TCP port on which the NFSv4 callback
  1085. channel should listen.
  1086. nfs.idmap_cache_timeout=
  1087. [NFS] set the maximum lifetime for idmapper cache
  1088. entries.
  1089. nfs.enable_ino64=
  1090. [NFS] enable 64-bit inode numbers.
  1091. If zero, the NFS client will fake up a 32-bit inode
  1092. number for the readdir() and stat() syscalls instead
  1093. of returning the full 64-bit number.
  1094. The default is to return 64-bit inode numbers.
  1095. nmi_debug= [KNL,AVR32] Specify one or more actions to take
  1096. when a NMI is triggered.
  1097. Format: [state][,regs][,debounce][,die]
  1098. nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
  1099. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  1100. emulation library even if a 387 maths coprocessor
  1101. is present.
  1102. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  1103. caches in the slab allocator. Saves per-node memory,
  1104. but will impact performance.
  1105. noalign [KNL,ARM]
  1106. noapic [SMP,APIC] Tells the kernel to not make use of any
  1107. IOAPICs that may be present in the system.
  1108. nobats [PPC] Do not use BATs for mapping kernel lowmem
  1109. on "Classic" PPC cores.
  1110. nocache [ARM]
  1111. nodelayacct [KNL] Disable per-task delay accounting
  1112. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  1113. noefi [X86-32,X86-64] Disable EFI runtime services support.
  1114. noexec [IA-64]
  1115. noexec [X86-32,X86-64]
  1116. On X86-32 available only on PAE configured kernels.
  1117. noexec=on: enable non-executable mappings (default)
  1118. noexec=off: disable non-executable mappings
  1119. noexec32 [X86-64]
  1120. This affects only 32-bit executables.
  1121. noexec32=on: enable non-executable mappings (default)
  1122. read doesn't imply executable mappings
  1123. noexec32=off: disable non-executable mappings
  1124. read implies executable mappings
  1125. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  1126. register save and restore. The kernel will only save
  1127. legacy floating-point registers on task switch.
  1128. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  1129. nohlt [BUGS=ARM]
  1130. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  1131. instruction doesn't work correctly and not to
  1132. use it.
  1133. nohalt [IA-64] Tells the kernel not to use the power saving
  1134. function PAL_HALT_LIGHT when idle. This increases
  1135. power-consumption. On the positive side, it reduces
  1136. interrupt wake-up latency, which may improve performance
  1137. in certain environments such as networked servers or
  1138. real-time systems.
  1139. nohz= [KNL] Boottime enable/disable dynamic ticks
  1140. Valid arguments: on, off
  1141. Default: on
  1142. noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
  1143. noirqdebug [X86-32] Disables the code which attempts to detect and
  1144. disable unhandled interrupt sources.
  1145. no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
  1146. broken timer IRQ sources.
  1147. noisapnp [ISAPNP] Disables ISA PnP code.
  1148. noinitrd [RAM] Tells the kernel not to load any configured
  1149. initial RAM disk.
  1150. nointroute [IA-64]
  1151. nojitter [IA64] Disables jitter checking for ITC timers.
  1152. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  1153. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  1154. noltlbs [PPC] Do not use large page/tlb entries for kernel
  1155. lowmem mapping on PPC40x.
  1156. nomca [IA-64] Disable machine check abort handling
  1157. nomce [X86-32] Machine Check Exception
  1158. nomfgpt [X86-32] Disable Multi-Function General Purpose
  1159. Timer usage (for AMD Geode machines).
  1160. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  1161. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1162. with UP alternatives
  1163. noresidual [PPC] Don't use residual data on PReP machines.
  1164. noresume [SWSUSP] Disables resume and restores original swap
  1165. space.
  1166. no-scroll [VGA] Disables scrollback.
  1167. This is required for the Braillex ib80-piezo Braille
  1168. reader made by F.H. Papenmeier (Germany).
  1169. nosbagart [IA-64]
  1170. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1171. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1172. and disable the IO APIC. legacy for "maxcpus=0".
  1173. nosoftlockup [KNL] Disable the soft-lockup detector.
  1174. nosync [HW,M68K] Disables sync negotiation for all devices.
  1175. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1176. nousb [USB] Disable the USB subsystem
  1177. nowb [ARM]
  1178. nptcg= [IA64] Override max number of concurrent global TLB
  1179. purges which is reported from either PAL_VM_SUMMARY or
  1180. SAL PALO.
  1181. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1182. one of ['zone', 'node', 'default'] can be specified
  1183. This can be set from sysctl after boot.
  1184. See Documentation/sysctl/vm.txt for details.
  1185. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1186. olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
  1187. Rather than timing out after 20 ms if an EC
  1188. command is not properly ACKed, override the length
  1189. of the timeout. We have interrupts disabled while
  1190. waiting for the ACK, so if this is set too high
  1191. interrupts *may* be lost!
  1192. opl3= [HW,OSS]
  1193. Format: <io>
  1194. oprofile.timer= [HW]
  1195. Use timer interrupt instead of performance counters
  1196. osst= [HW,SCSI] SCSI Tape Driver
  1197. Format: <buffer_size>,<write_threshold>
  1198. See also Documentation/scsi/st.txt.
  1199. panic= [KNL] Kernel behaviour on panic
  1200. Format: <timeout>
  1201. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1202. connected to, default is 0.
  1203. Format: <parport#>
  1204. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1205. 0 for XT, 1 for AT (default is AT).
  1206. Format: <mode>
  1207. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1208. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1209. Use 'auto' to force the driver to use any
  1210. IRQ/DMA settings detected (the default is to
  1211. ignore detected IRQ/DMA settings because of
  1212. possible conflicts). You can specify the base
  1213. address, IRQ, and DMA settings; IRQ and DMA
  1214. should be numbers, or 'auto' (for using detected
  1215. settings on that particular port), or 'nofifo'
  1216. (to avoid using a FIFO even if it is detected).
  1217. Parallel ports are assigned in the order they
  1218. are specified on the command line, starting
  1219. with parport0.
  1220. parport_init_mode= [HW,PPT]
  1221. Configure VIA parallel port to operate in
  1222. a specific mode. This is necessary on Pegasos
  1223. computer where firmware has no options for setting
  1224. up parallel port mode and sets it to spp.
  1225. Currently this function knows 686a and 8231 chips.
  1226. Format: [spp|ps2|epp|ecp|ecpepp]
  1227. pas2= [HW,OSS] Format:
  1228. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1229. pas16= [HW,SCSI]
  1230. See header of drivers/scsi/pas16.c.
  1231. pause_on_oops=
  1232. Halt all CPUs after the first oops has been printed for
  1233. the specified number of seconds. This is to be used if
  1234. your oopses keep scrolling off the screen.
  1235. pcbit= [HW,ISDN]
  1236. pcd. [PARIDE]
  1237. See header of drivers/block/paride/pcd.c.
  1238. See also Documentation/paride.txt.
  1239. pci=option[,option...] [PCI] various PCI subsystem options:
  1240. off [X86-32] don't probe for the PCI bus
  1241. bios [X86-32] force use of PCI BIOS, don't access
  1242. the hardware directly. Use this if your machine
  1243. has a non-standard PCI host bridge.
  1244. nobios [X86-32] disallow use of PCI BIOS, only direct
  1245. hardware access methods are allowed. Use this
  1246. if you experience crashes upon bootup and you
  1247. suspect they are caused by the BIOS.
  1248. conf1 [X86-32] Force use of PCI Configuration
  1249. Mechanism 1.
  1250. conf2 [X86-32] Force use of PCI Configuration
  1251. Mechanism 2.
  1252. noaer [PCIE] If the PCIEAER kernel config parameter is
  1253. enabled, this kernel boot option can be used to
  1254. disable the use of PCIE advanced error reporting.
  1255. nodomains [PCI] Disable support for multiple PCI
  1256. root domains (aka PCI segments, in ACPI-speak).
  1257. nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
  1258. Configuration
  1259. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1260. enabled, this kernel boot option can be used to
  1261. disable the use of MSI interrupts system-wide.
  1262. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1263. routing table. These calls are known to be buggy
  1264. on several machines and they hang the machine
  1265. when used, but on other computers it's the only
  1266. way to get the interrupt routing table. Try
  1267. this option if the kernel is unable to allocate
  1268. IRQs or discover secondary PCI buses on your
  1269. motherboard.
  1270. rom [X86-32] Assign address space to expansion ROMs.
  1271. Use with caution as certain devices share
  1272. address decoders between ROMs and other
  1273. resources.
  1274. norom [X86-32,X86_64] Do not assign address space to
  1275. expansion ROMs that do not already have
  1276. BIOS assigned address ranges.
  1277. irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
  1278. assigned automatically to PCI devices. You can
  1279. make the kernel exclude IRQs of your ISA cards
  1280. this way.
  1281. pirqaddr=0xAAAAA [X86-32] Specify the physical address
  1282. of the PIRQ table (normally generated
  1283. by the BIOS) if it is outside the
  1284. F0000h-100000h range.
  1285. lastbus=N [X86-32] Scan all buses thru bus #N. Can be
  1286. useful if the kernel is unable to find your
  1287. secondary buses and you want to tell it
  1288. explicitly which ones they are.
  1289. assign-busses [X86-32] Always assign all PCI bus
  1290. numbers ourselves, overriding
  1291. whatever the firmware may have done.
  1292. usepirqmask [X86-32] Honor the possible IRQ mask stored
  1293. in the BIOS $PIR table. This is needed on
  1294. some systems with broken BIOSes, notably
  1295. some HP Pavilion N5400 and Omnibook XE3
  1296. notebooks. This will have no effect if ACPI
  1297. IRQ routing is enabled.
  1298. noacpi [X86-32] Do not use ACPI for IRQ routing
  1299. or for PCI scanning.
  1300. use_crs [X86-32] Use _CRS for PCI resource
  1301. allocation.
  1302. routeirq Do IRQ routing for all PCI devices.
  1303. This is normally done in pci_enable_device(),
  1304. so this option is a temporary workaround
  1305. for broken drivers that don't call it.
  1306. skip_isa_align [X86] do not align io start addr, so can
  1307. handle more pci cards
  1308. firmware [ARM] Do not re-enumerate the bus but instead
  1309. just use the configuration from the
  1310. bootloader. This is currently used on
  1311. IXP2000 systems where the bus has to be
  1312. configured a certain way for adjunct CPUs.
  1313. noearly [X86] Don't do any early type 1 scanning.
  1314. This might help on some broken boards which
  1315. machine check when some devices' config space
  1316. is read. But various workarounds are disabled
  1317. and some IOMMU drivers will not work.
  1318. bfsort Sort PCI devices into breadth-first order.
  1319. This sorting is done to get a device
  1320. order compatible with older (<= 2.4) kernels.
  1321. nobfsort Don't sort PCI devices into breadth-first order.
  1322. cbiosize=nn[KMG] The fixed amount of bus space which is
  1323. reserved for the CardBus bridge's IO window.
  1324. The default value is 256 bytes.
  1325. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1326. reserved for the CardBus bridge's memory
  1327. window. The default value is 64 megabytes.
  1328. pcmv= [HW,PCMCIA] BadgePAD 4
  1329. pd. [PARIDE]
  1330. See Documentation/paride.txt.
  1331. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1332. boot time.
  1333. Format: { 0 | 1 }
  1334. See arch/parisc/kernel/pdc_chassis.c
  1335. pf. [PARIDE]
  1336. See Documentation/paride.txt.
  1337. pg. [PARIDE]
  1338. See Documentation/paride.txt.
  1339. pirq= [SMP,APIC] Manual mp-table setup
  1340. See Documentation/i386/IO-APIC.txt.
  1341. plip= [PPT,NET] Parallel port network link
  1342. Format: { parport<nr> | timid | 0 }
  1343. See also Documentation/parport.txt.
  1344. pmtmr= [X86] Manual setup of pmtmr I/O Port.
  1345. Override pmtimer IOPort with a hex value.
  1346. e.g. pmtmr=0x508
  1347. pnp.debug [PNP]
  1348. Enable PNP debug messages. This depends on the
  1349. CONFIG_PNP_DEBUG_MESSAGES option.
  1350. pnpacpi= [ACPI]
  1351. { off }
  1352. pnpbios= [ISAPNP]
  1353. { on | off | curr | res | no-curr | no-res }
  1354. pnp_reserve_irq=
  1355. [ISAPNP] Exclude IRQs for the autoconfiguration
  1356. pnp_reserve_dma=
  1357. [ISAPNP] Exclude DMAs for the autoconfiguration
  1358. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1359. Ranges are in pairs (I/O port base and size).
  1360. pnp_reserve_mem=
  1361. [ISAPNP] Exclude memory regions for the
  1362. autoconfiguration.
  1363. Ranges are in pairs (memory base and size).
  1364. print-fatal-signals=
  1365. [KNL] debug: print fatal signals
  1366. print-fatal-signals=1: print segfault info to
  1367. the kernel console.
  1368. default: off.
  1369. printk.time= Show timing data prefixed to each printk message line
  1370. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1371. profile= [KNL] Enable kernel profiling via /proc/profile
  1372. Format: [schedule,]<number>
  1373. Param: "schedule" - profile schedule points.
  1374. Param: <number> - step/bucket size as a power of 2 for
  1375. statistical time based profiling.
  1376. Param: "sleep" - profile D-state sleeping (millisecs).
  1377. Requires CONFIG_SCHEDSTATS
  1378. Param: "kvm" - profile VM exits.
  1379. processor.max_cstate= [HW,ACPI]
  1380. Limit processor to maximum C-state
  1381. max_cstate=9 overrides any DMI blacklist limit.
  1382. processor.nocst [HW,ACPI]
  1383. Ignore the _CST method to determine C-states,
  1384. instead using the legacy FADT method
  1385. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1386. before loading.
  1387. See Documentation/ramdisk.txt.
  1388. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1389. probe for; one of (bare|imps|exps|lifebook|any).
  1390. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1391. per second.
  1392. psmouse.resetafter= [HW,MOUSE]
  1393. Try to reset the device after so many bad packets
  1394. (0 = never).
  1395. psmouse.resolution=
  1396. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1397. psmouse.smartscroll=
  1398. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1399. 0 = disabled, 1 = enabled (default).
  1400. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1401. Format:
  1402. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1403. pt. [PARIDE]
  1404. See Documentation/paride.txt.
  1405. pty.legacy_count=
  1406. [KNL] Number of legacy pty's. Overwrites compiled-in
  1407. default number.
  1408. quiet [KNL] Disable most log messages
  1409. r128= [HW,DRM]
  1410. raid= [HW,RAID]
  1411. See Documentation/md.txt.
  1412. ramdisk_blocksize= [RAM]
  1413. See Documentation/ramdisk.txt.
  1414. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1415. See Documentation/ramdisk.txt.
  1416. rcupdate.blimit= [KNL,BOOT]
  1417. Set maximum number of finished RCU callbacks to process
  1418. in one batch.
  1419. rcupdate.qhimark= [KNL,BOOT]
  1420. Set threshold of queued
  1421. RCU callbacks over which batch limiting is disabled.
  1422. rcupdate.qlowmark= [KNL,BOOT]
  1423. Set threshold of queued RCU callbacks below which
  1424. batch limiting is re-enabled.
  1425. rdinit= [KNL]
  1426. Format: <full_path>
  1427. Run specified binary instead of /init from the ramdisk,
  1428. used for early userspace startup. See initrd.
  1429. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1430. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1431. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1432. relax_domain_level=
  1433. [KNL, SMP] Set scheduler's default relax_domain_level.
  1434. See Documentation/cpusets.txt.
  1435. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1436. reservetop= [X86-32]
  1437. Format: nn[KMG]
  1438. Reserves a hole at the top of the kernel virtual
  1439. address space.
  1440. reset_devices [KNL] Force drivers to reset the underlying device
  1441. during initialization.
  1442. resume= [SWSUSP]
  1443. Specify the partition device for software suspend
  1444. resume_offset= [SWSUSP]
  1445. Specify the offset from the beginning of the partition
  1446. given by "resume=" at which the swap header is located,
  1447. in <PAGE_SIZE> units (needed only for swap files).
  1448. See Documentation/power/swsusp-and-swap-files.txt
  1449. retain_initrd [RAM] Keep initrd memory after extraction
  1450. rhash_entries= [KNL,NET]
  1451. Set number of hash buckets for route cache
  1452. riscom8= [HW,SERIAL]
  1453. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1454. ro [KNL] Mount root device read-only on boot
  1455. root= [KNL] Root filesystem
  1456. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1457. mount the root filesystem
  1458. rootflags= [KNL] Set root filesystem mount option string
  1459. rootfstype= [KNL] Set root filesystem type
  1460. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1461. Useful for devices that are detected asynchronously
  1462. (e.g. USB and MMC devices).
  1463. root_plug.vendor_id=
  1464. [ROOTPLUG] Override the default vendor ID
  1465. root_plug.product_id=
  1466. [ROOTPLUG] Override the default product ID
  1467. root_plug.debug=
  1468. [ROOTPLUG] Enable debugging output
  1469. rw [KNL] Mount root device read-write on boot
  1470. S [KNL] Run init in single mode
  1471. sa1100ir [NET]
  1472. See drivers/net/irda/sa1100_ir.c.
  1473. sbni= [NET] Granch SBNI12 leased line adapter
  1474. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1475. Format: <io>[,<timeout>[,<isapnp>]]
  1476. scsi_debug_*= [SCSI]
  1477. See drivers/scsi/scsi_debug.c.
  1478. scsi_default_dev_flags=
  1479. [SCSI] SCSI default device flags
  1480. Format: <integer>
  1481. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1482. Format: <vendor>:<model>:<flags>
  1483. (flags are integer value)
  1484. scsi_logging_level= [SCSI] a bit mask of logging levels
  1485. See drivers/scsi/scsi_logging.h for bits. Also
  1486. settable via sysctl at dev.scsi.logging_level
  1487. (/proc/sys/dev/scsi/logging_level).
  1488. There is also a nice 'scsi_logging_level' script in the
  1489. S390-tools package, available for download at
  1490. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1491. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1492. discovered. async scans them in kernel threads,
  1493. allowing boot to proceed. none ignores them, expecting
  1494. user space to do the scan.
  1495. selinux [SELINUX] Disable or enable SELinux at boot time.
  1496. Format: { "0" | "1" }
  1497. See security/selinux/Kconfig help text.
  1498. 0 -- disable.
  1499. 1 -- enable.
  1500. Default value is set via kernel config option.
  1501. If enabled at boot time, /selinux/disable can be used
  1502. later to disable prior to initial policy load.
  1503. selinux_compat_net =
  1504. [SELINUX] Set initial selinux_compat_net flag value.
  1505. Format: { "0" | "1" }
  1506. 0 -- use new secmark-based packet controls
  1507. 1 -- use legacy packet controls
  1508. Default value is 0 (preferred).
  1509. Value can be changed at runtime via
  1510. /selinux/compat_net.
  1511. serialnumber [BUGS=X86-32]
  1512. shapers= [NET]
  1513. Maximal number of shapers.
  1514. sim710= [SCSI,HW]
  1515. See header of drivers/scsi/sim710.c.
  1516. simeth= [IA-64]
  1517. simscsi=
  1518. slram= [HW,MTD]
  1519. slub_debug[=options[,slabs]] [MM, SLUB]
  1520. Enabling slub_debug allows one to determine the
  1521. culprit if slab objects become corrupted. Enabling
  1522. slub_debug can create guard zones around objects and
  1523. may poison objects when not in use. Also tracks the
  1524. last alloc / free. For more information see
  1525. Documentation/vm/slub.txt.
  1526. slub_max_order= [MM, SLUB]
  1527. Determines the maximum allowed order for slabs.
  1528. A high setting may cause OOMs due to memory
  1529. fragmentation. For more information see
  1530. Documentation/vm/slub.txt.
  1531. slub_min_objects= [MM, SLUB]
  1532. The minimum number of objects per slab. SLUB will
  1533. increase the slab order up to slub_max_order to
  1534. generate a sufficiently large slab able to contain
  1535. the number of objects indicated. The higher the number
  1536. of objects the smaller the overhead of tracking slabs
  1537. and the less frequently locks need to be acquired.
  1538. For more information see Documentation/vm/slub.txt.
  1539. slub_min_order= [MM, SLUB]
  1540. Determines the mininum page order for slabs. Must be
  1541. lower than slub_max_order.
  1542. For more information see Documentation/vm/slub.txt.
  1543. slub_nomerge [MM, SLUB]
  1544. Disable merging of slabs with similar size. May be
  1545. necessary if there is some reason to distinguish
  1546. allocs to different slabs. Debug options disable
  1547. merging on their own.
  1548. For more information see Documentation/vm/slub.txt.
  1549. smart2= [HW]
  1550. Format: <io1>[,<io2>[,...,<io8>]]
  1551. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1552. attempt to substitute SMP alternatives once at boot.
  1553. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1554. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1555. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1556. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1557. smsc-ircc2.ircc_irq= [HW] IRQ line
  1558. smsc-ircc2.ircc_dma= [HW] DMA channel
  1559. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1560. 0: Toshiba Satellite 1800 (GP data pin select)
  1561. 1: Fast pin select (default)
  1562. 2: ATC IRMode
  1563. snd-ad1816a= [HW,ALSA]
  1564. snd-ad1848= [HW,ALSA]
  1565. snd-ali5451= [HW,ALSA]
  1566. snd-als100= [HW,ALSA]
  1567. snd-als4000= [HW,ALSA]
  1568. snd-azt2320= [HW,ALSA]
  1569. snd-cmi8330= [HW,ALSA]
  1570. snd-cmipci= [HW,ALSA]
  1571. snd-cs4231= [HW,ALSA]
  1572. snd-cs4232= [HW,ALSA]
  1573. snd-cs4236= [HW,ALSA]
  1574. snd-cs4281= [HW,ALSA]
  1575. snd-cs46xx= [HW,ALSA]
  1576. snd-dt019x= [HW,ALSA]
  1577. snd-dummy= [HW,ALSA]
  1578. snd-emu10k1= [HW,ALSA]
  1579. snd-ens1370= [HW,ALSA]
  1580. snd-ens1371= [HW,ALSA]
  1581. snd-es968= [HW,ALSA]
  1582. snd-es1688= [HW,ALSA]
  1583. snd-es18xx= [HW,ALSA]
  1584. snd-es1938= [HW,ALSA]
  1585. snd-es1968= [HW,ALSA]
  1586. snd-fm801= [HW,ALSA]
  1587. snd-gusclassic= [HW,ALSA]
  1588. snd-gusextreme= [HW,ALSA]
  1589. snd-gusmax= [HW,ALSA]
  1590. snd-hdsp= [HW,ALSA]
  1591. snd-ice1712= [HW,ALSA]
  1592. snd-intel8x0= [HW,ALSA]
  1593. snd-interwave= [HW,ALSA]
  1594. snd-interwave-stb=
  1595. [HW,ALSA]
  1596. snd-korg1212= [HW,ALSA]
  1597. snd-maestro3= [HW,ALSA]
  1598. snd-mpu401= [HW,ALSA]
  1599. snd-mtpav= [HW,ALSA]
  1600. snd-nm256= [HW,ALSA]
  1601. snd-opl3sa2= [HW,ALSA]
  1602. snd-opti92x-ad1848=
  1603. [HW,ALSA]
  1604. snd-opti92x-cs4231=
  1605. [HW,ALSA]
  1606. snd-opti93x= [HW,ALSA]
  1607. snd-pmac= [HW,ALSA]
  1608. snd-rme32= [HW,ALSA]
  1609. snd-rme96= [HW,ALSA]
  1610. snd-rme9652= [HW,ALSA]
  1611. snd-sb8= [HW,ALSA]
  1612. snd-sb16= [HW,ALSA]
  1613. snd-sbawe= [HW,ALSA]
  1614. snd-serial= [HW,ALSA]
  1615. snd-sgalaxy= [HW,ALSA]
  1616. snd-sonicvibes= [HW,ALSA]
  1617. snd-sun-amd7930=
  1618. [HW,ALSA]
  1619. snd-sun-cs4231= [HW,ALSA]
  1620. snd-trident= [HW,ALSA]
  1621. snd-usb-audio= [HW,ALSA,USB]
  1622. snd-via82xx= [HW,ALSA]
  1623. snd-virmidi= [HW,ALSA]
  1624. snd-wavefront= [HW,ALSA]
  1625. snd-ymfpci= [HW,ALSA]
  1626. softlockup_panic=
  1627. [KNL] Should the soft-lockup detector generate panics.
  1628. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1629. See Documentation/sonypi.txt
  1630. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1631. See Documentation/specialix.txt.
  1632. spia_io_base= [HW,MTD]
  1633. spia_fio_base=
  1634. spia_pedr=
  1635. spia_peddr=
  1636. sscape= [HW,OSS]
  1637. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1638. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1639. See Documentation/scsi/st.txt.
  1640. sti= [PARISC,HW]
  1641. Format: <num>
  1642. Set the STI (builtin display/keyboard on the HP-PARISC
  1643. machines) console (graphic card) which should be used
  1644. as the initial boot-console.
  1645. See also comment in drivers/video/console/sticore.c.
  1646. sti_font= [HW]
  1647. See comment in drivers/video/console/sticore.c.
  1648. stifb= [HW]
  1649. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1650. sunrpc.pool_mode=
  1651. [NFS]
  1652. Control how the NFS server code allocates CPUs to
  1653. service thread pools. Depending on how many NICs
  1654. you have and where their interrupts are bound, this
  1655. option will affect which CPUs will do NFS serving.
  1656. Note: this parameter cannot be changed while the
  1657. NFS server is running.
  1658. auto the server chooses an appropriate mode
  1659. automatically using heuristics
  1660. global a single global pool contains all CPUs
  1661. percpu one pool for each CPU
  1662. pernode one pool for each NUMA node (equivalent
  1663. to global on non-NUMA machines)
  1664. swiotlb= [IA-64] Number of I/O TLB slabs
  1665. switches= [HW,M68k]
  1666. sym53c416= [HW,SCSI]
  1667. See header of drivers/scsi/sym53c416.c.
  1668. sysrq_always_enabled
  1669. [KNL]
  1670. Ignore sysrq setting - this boot parameter will
  1671. neutralize any effect of /proc/sys/kernel/sysrq.
  1672. Useful for debugging.
  1673. t128= [HW,SCSI]
  1674. See header of drivers/scsi/t128.c.
  1675. tdfx= [HW,DRM]
  1676. test_suspend= [SUSPEND]
  1677. Specify "mem" (for Suspend-to-RAM) or "standby" (for
  1678. standby suspend) as the system sleep state to briefly
  1679. enter during system startup. The system is woken from
  1680. this state using a wakeup-capable RTC alarm.
  1681. thash_entries= [KNL,NET]
  1682. Set number of hash buckets for TCP connection
  1683. thermal.act= [HW,ACPI]
  1684. -1: disable all active trip points in all thermal zones
  1685. <degrees C>: override all lowest active trip points
  1686. thermal.crt= [HW,ACPI]
  1687. -1: disable all critical trip points in all thermal zones
  1688. <degrees C>: override all critical trip points
  1689. thermal.nocrt= [HW,ACPI]
  1690. Set to disable actions on ACPI thermal zone
  1691. critical and hot trip points.
  1692. thermal.off= [HW,ACPI]
  1693. 1: disable ACPI thermal control
  1694. thermal.psv= [HW,ACPI]
  1695. -1: disable all passive trip points
  1696. <degrees C>: override all passive trip points to this value
  1697. thermal.tzp= [HW,ACPI]
  1698. Specify global default ACPI thermal zone polling rate
  1699. <deci-seconds>: poll all this frequency
  1700. 0: no polling (default)
  1701. tmscsim= [HW,SCSI]
  1702. See comment before function dc390_setup() in
  1703. drivers/scsi/tmscsim.c.
  1704. tp720= [HW,PS2]
  1705. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1706. Format:
  1707. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1708. turbografx.map[2|3]= [HW,JOY]
  1709. TurboGraFX parallel port interface
  1710. Format:
  1711. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1712. See also Documentation/input/joystick-parport.txt
  1713. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1714. See header of drivers/scsi/u14-34f.c.
  1715. uart401= [HW,OSS]
  1716. Format: <io>,<irq>
  1717. uart6850= [HW,OSS]
  1718. Format: <io>,<irq>
  1719. uhci-hcd.ignore_oc=
  1720. [USB] Ignore overcurrent events (default N).
  1721. Some badly-designed motherboards generate lots of
  1722. bogus events, for ports that aren't wired to
  1723. anything. Set this parameter to avoid log spamming.
  1724. Note that genuine overcurrent events won't be
  1725. reported either.
  1726. unknown_nmi_panic
  1727. [X86-32,X86-64]
  1728. Set unknown_nmi_panic=1 early on boot.
  1729. usbcore.autosuspend=
  1730. [USB] The autosuspend time delay (in seconds) used
  1731. for newly-detected USB devices (default 2). This
  1732. is the time required before an idle device will be
  1733. autosuspended. Devices for which the delay is set
  1734. to a negative value won't be autosuspended at all.
  1735. usbhid.mousepoll=
  1736. [USBHID] The interval which mice are to be polled at.
  1737. add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
  1738. kernel's map of available physical RAM.
  1739. vdso= [X86-32,SH,x86-64]
  1740. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  1741. vdso=1: enable VDSO (default)
  1742. vdso=0: disable VDSO mapping
  1743. vdso32= [X86-32,X86-64]
  1744. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  1745. vdso32=1: enable 32-bit VDSO (default)
  1746. vdso32=0: disable 32-bit VDSO mapping
  1747. vector= [IA-64,SMP]
  1748. vector=percpu: enable percpu vector domain
  1749. video= [FB] Frame buffer configuration
  1750. See Documentation/fb/modedb.txt.
  1751. vga= [BOOT,X86-32] Select a particular video mode
  1752. See Documentation/i386/boot.txt and
  1753. Documentation/svga.txt.
  1754. Use vga=ask for menu.
  1755. This is actually a boot loader parameter; the value is
  1756. passed to the kernel using a special protocol.
  1757. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1758. size of <nn>. This can be used to increase the
  1759. minimum size (128MB on x86). It can also be used to
  1760. decrease the size and leave more room for directly
  1761. mapped kernel RAM.
  1762. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1763. Format: <command>
  1764. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1765. Format: <command>
  1766. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1767. Format: <command>
  1768. waveartist= [HW,OSS]
  1769. Format: <io>,<irq>,<dma>,<dma2>
  1770. wd33c93= [HW,SCSI]
  1771. See header of drivers/scsi/wd33c93.c.
  1772. wd7000= [HW,SCSI]
  1773. See header of drivers/scsi/wd7000.c.
  1774. wdt= [WDT] Watchdog
  1775. See Documentation/watchdog/wdt.txt.
  1776. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1777. xd_geo= See header of drivers/block/xd.c.
  1778. xirc2ps_cs= [NET,PCMCIA]
  1779. Format:
  1780. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1781. norandmaps Don't use address space randomization
  1782. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
  1783. ______________________________________________________________________
  1784. TODO:
  1785. Add documentation for ALSA options.
  1786. Add more DRM drivers.