kernel-parameters.txt 60 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878879880881882883884885886887888889890891892893894895896897898899900901902903904905906907908909910911912913914915916917918919920921922923924925926927928929930931932933934935936937938939940941942943944945946947948949950951952953954955956957958959960961962963964965966967968969970971972973974975976977978979980981982983984985986987988989990991992993994995996997998999100010011002100310041005100610071008100910101011101210131014101510161017101810191020102110221023102410251026102710281029103010311032103310341035103610371038103910401041104210431044104510461047104810491050105110521053105410551056105710581059106010611062106310641065106610671068106910701071107210731074107510761077107810791080108110821083108410851086108710881089109010911092109310941095109610971098109911001101110211031104110511061107110811091110111111121113111411151116111711181119112011211122112311241125112611271128112911301131113211331134113511361137113811391140114111421143114411451146114711481149115011511152115311541155115611571158115911601161116211631164116511661167116811691170117111721173117411751176117711781179118011811182118311841185118611871188118911901191119211931194119511961197119811991200120112021203120412051206120712081209121012111212121312141215121612171218121912201221122212231224122512261227122812291230123112321233123412351236123712381239124012411242124312441245124612471248124912501251125212531254125512561257125812591260126112621263126412651266126712681269127012711272127312741275127612771278127912801281128212831284128512861287128812891290129112921293129412951296129712981299130013011302130313041305130613071308130913101311131213131314131513161317131813191320132113221323132413251326132713281329133013311332133313341335133613371338133913401341134213431344134513461347134813491350135113521353135413551356135713581359136013611362136313641365136613671368136913701371137213731374137513761377137813791380138113821383138413851386138713881389139013911392139313941395139613971398139914001401140214031404140514061407140814091410141114121413141414151416141714181419142014211422142314241425142614271428142914301431143214331434143514361437143814391440144114421443144414451446144714481449145014511452145314541455145614571458145914601461146214631464146514661467146814691470147114721473147414751476147714781479148014811482148314841485148614871488148914901491149214931494149514961497149814991500150115021503150415051506150715081509151015111512151315141515151615171518151915201521152215231524152515261527152815291530153115321533153415351536153715381539154015411542154315441545154615471548154915501551155215531554155515561557155815591560156115621563156415651566156715681569157015711572157315741575157615771578157915801581158215831584158515861587158815891590159115921593159415951596159715981599160016011602160316041605160616071608160916101611161216131614161516161617161816191620162116221623162416251626162716281629163016311632163316341635163616371638163916401641164216431644164516461647164816491650165116521653165416551656165716581659166016611662166316641665166616671668166916701671167216731674167516761677167816791680168116821683168416851686168716881689169016911692169316941695169616971698169917001701170217031704170517061707170817091710171117121713171417151716171717181719172017211722172317241725172617271728172917301731173217331734173517361737173817391740174117421743174417451746174717481749175017511752175317541755175617571758175917601761176217631764176517661767176817691770177117721773177417751776177717781779178017811782178317841785178617871788178917901791179217931794179517961797179817991800180118021803180418051806180718081809181018111812181318141815181618171818181918201821182218231824182518261827182818291830183118321833183418351836183718381839184018411842184318441845184618471848184918501851185218531854185518561857185818591860186118621863186418651866186718681869187018711872187318741875187618771878187918801881188218831884188518861887188818891890189118921893189418951896189718981899190019011902190319041905190619071908190919101911191219131914191519161917191819191920192119221923192419251926192719281929193019311932193319341935193619371938193919401941194219431944194519461947194819491950195119521953195419551956195719581959196019611962196319641965196619671968
  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. AX25 Appropriate AX.25 support is enabled.
  30. DRM Direct Rendering Management support is enabled.
  31. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
  32. EFI EFI Partitioning (GPT) is enabled
  33. EIDE EIDE/ATAPI support is enabled.
  34. FB The frame buffer device is enabled.
  35. HW Appropriate hardware is enabled.
  36. IA-64 IA-64 architecture is enabled.
  37. IOSCHED More than one I/O scheduler is enabled.
  38. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  39. ISAPNP ISA PnP code is enabled.
  40. ISDN Appropriate ISDN support is enabled.
  41. JOY Appropriate joystick support is enabled.
  42. LIBATA Libata driver is enabled
  43. LP Printer support is enabled.
  44. LOOP Loopback device support is enabled.
  45. M68k M68k architecture is enabled.
  46. These options have more detailed description inside of
  47. Documentation/m68k/kernel-options.txt.
  48. MCA MCA bus support is enabled.
  49. MDA MDA console support is enabled.
  50. MOUSE Appropriate mouse support is enabled.
  51. MSI Message Signaled Interrupts (PCI).
  52. MTD MTD (Memory Technology Device) support is enabled.
  53. NET Appropriate network support is enabled.
  54. NUMA NUMA support is enabled.
  55. GENERIC_TIME The generic timeofday code is enabled.
  56. NFS Appropriate NFS support is enabled.
  57. OSS OSS sound support is enabled.
  58. PV_OPS A paravirtualized kernel is enabled.
  59. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  60. PARISC The PA-RISC architecture is enabled.
  61. PCI PCI bus support is enabled.
  62. PCMCIA The PCMCIA subsystem is enabled.
  63. PNP Plug & Play support is enabled.
  64. PPC PowerPC architecture is enabled.
  65. PPT Parallel port support is enabled.
  66. PS2 Appropriate PS/2 support is enabled.
  67. RAM RAM disk support is enabled.
  68. S390 S390 architecture is enabled.
  69. SCSI Appropriate SCSI support is enabled.
  70. A lot of drivers has their options described inside of
  71. Documentation/scsi/.
  72. SELINUX SELinux support is enabled.
  73. SERIAL Serial support is enabled.
  74. SH SuperH architecture is enabled.
  75. SMP The kernel is an SMP kernel.
  76. SPARC Sparc architecture is enabled.
  77. SWSUSP Software suspend is enabled.
  78. TS Appropriate touchscreen support is enabled.
  79. USB USB support is enabled.
  80. USBHID USB Human Interface Device support is enabled.
  81. V4L Video For Linux support is enabled.
  82. VGA The VGA console has been enabled.
  83. VT Virtual terminal support is enabled.
  84. WDT Watchdog support is enabled.
  85. XT IBM PC/XT MFM hard disk support is enabled.
  86. X86-32 X86-32, aka i386 architecture is enabled.
  87. X86-64 X86-64 architecture is enabled.
  88. More X86-64 boot options can be found in
  89. Documentation/x86_64/boot-options.txt .
  90. In addition, the following text indicates that the option:
  91. BUGS= Relates to possible processor bugs on the said processor.
  92. KNL Is a kernel start-up parameter.
  93. BOOT Is a boot loader parameter.
  94. Parameters denoted with BOOT are actually interpreted by the boot
  95. loader, and have no meaning to the kernel directly.
  96. Do not modify the syntax of boot loader parameters without extreme
  97. need or coordination with <Documentation/i386/boot.txt>.
  98. There are also arch-specific kernel-parameters not documented here.
  99. See for example <Documentation/x86_64/boot-options.txt>.
  100. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  101. a trailing = on the name of any parameter states that that parameter will
  102. be entered as an environment variable, whereas its absence indicates that
  103. it will appear as a kernel argument readable via /proc/cmdline by programs
  104. running once the system is up.
  105. The number of kernel parameters is not limited, but the length of the
  106. complete command line (parameters including spaces etc.) is limited to
  107. a fixed number of characters. This limit depends on the architecture
  108. and is between 256 and 4096 characters. It is defined in the file
  109. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  110. acpi= [HW,ACPI,X86-64,i386]
  111. Advanced Configuration and Power Interface
  112. Format: { force | off | ht | strict | noirq }
  113. force -- enable ACPI if default was off
  114. off -- disable ACPI if default was on
  115. noirq -- do not use ACPI for IRQ routing
  116. ht -- run only enough ACPI to enable Hyper Threading
  117. strict -- Be less tolerant of platforms that are not
  118. strictly ACPI specification compliant.
  119. See also Documentation/pm.txt, pci=noacpi
  120. acpi_apic_instance= [ACPI, IOAPIC]
  121. Format: <int>
  122. 2: use 2nd APIC table, if available
  123. 1,0: use 1st APIC table
  124. default: 0
  125. acpi_sleep= [HW,ACPI] Sleep options
  126. Format: { s3_bios, s3_mode }
  127. See Documentation/power/video.txt
  128. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  129. Format: { level | edge | high | low }
  130. acpi_irq_balance [HW,ACPI]
  131. ACPI will balance active IRQs
  132. default in APIC mode
  133. acpi_irq_nobalance [HW,ACPI]
  134. ACPI will not move active IRQs (default)
  135. default in PIC mode
  136. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  137. use by PCI
  138. Format: <irq>,<irq>...
  139. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  140. Format: <irq>,<irq>...
  141. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  142. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  143. Format: To spoof as Windows 98: ="Microsoft Windows"
  144. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  145. acpi_osi="string1" # add string1 -- only one string
  146. acpi_osi="!string2" # remove built-in string2
  147. acpi_osi= # disable all strings
  148. acpi_serialize [HW,ACPI] force serialization of AML methods
  149. acpi_skip_timer_override [HW,ACPI]
  150. Recognize and ignore IRQ0/pin2 Interrupt Override.
  151. For broken nForce2 BIOS resulting in XT-PIC timer.
  152. acpi_use_timer_override [HW,ACPI}
  153. Use timer override. For some broken Nvidia NF5 boards
  154. that require a timer override, but don't have
  155. HPET
  156. acpi.debug_layer= [HW,ACPI]
  157. Format: <int>
  158. Each bit of the <int> indicates an ACPI debug layer,
  159. 1: enable, 0: disable. It is useful for boot time
  160. debugging. After system has booted up, it can be set
  161. via /sys/module/acpi/parameters/debug_layer.
  162. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  163. Available bits (add the numbers together) to enable debug output
  164. for specific parts of the ACPI subsystem:
  165. 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
  166. 0x10 namespace 0x20 parser 0x40 dispatcher
  167. 0x80 executer 0x100 resources 0x200 acpica debugger
  168. 0x400 os services 0x800 acpica disassembler.
  169. The number can be in decimal or prefixed with 0x in hex.
  170. Warning: Many of these options can produce a lot of
  171. output and make your system unusable. Be very careful.
  172. acpi.debug_level= [HW,ACPI]
  173. Format: <int>
  174. Each bit of the <int> indicates an ACPI debug level,
  175. 1: enable, 0: disable. It is useful for boot time
  176. debugging. After system has booted up, it can be set
  177. via /sys/module/acpi/parameters/debug_level.
  178. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  179. Available bits (add the numbers together) to enable different
  180. debug output levels of the ACPI subsystem:
  181. 0x01 error 0x02 warn 0x04 init 0x08 debug object
  182. 0x10 info 0x20 init names 0x40 parse 0x80 load
  183. 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
  184. 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
  185. 0x10000 resources 0x20000 user requests 0x40000 package.
  186. The number can be in decimal or prefixed with 0x in hex.
  187. Warning: Many of these options can produce a lot of
  188. output and make your system unusable. Be very careful.
  189. acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
  190. acpi_pm_good [X86-32,X86-64]
  191. Override the pmtimer bug detection: force the kernel
  192. to assume that this machine's pmtimer latches its value
  193. and always returns good values.
  194. agp= [AGP]
  195. { off | try_unsupported }
  196. off: disable AGP support
  197. try_unsupported: try to drive unsupported chipsets
  198. (may crash computer or cause data corruption)
  199. enable_timer_pin_1 [i386,x86-64]
  200. Enable PIN 1 of APIC timer
  201. Can be useful to work around chipset bugs
  202. (in particular on some ATI chipsets).
  203. The kernel tries to set a reasonable default.
  204. disable_timer_pin_1 [i386,x86-64]
  205. Disable PIN 1 of APIC timer
  206. Can be useful to work around chipset bugs.
  207. ad1848= [HW,OSS]
  208. Format: <io>,<irq>,<dma>,<dma2>,<type>
  209. advansys= [HW,SCSI]
  210. See header of drivers/scsi/advansys.c.
  211. advwdt= [HW,WDT] Advantech WDT
  212. Format: <iostart>,<iostop>
  213. aedsp16= [HW,OSS] Audio Excel DSP 16
  214. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  215. See also header of sound/oss/aedsp16.c.
  216. aha152x= [HW,SCSI]
  217. See Documentation/scsi/aha152x.txt.
  218. aha1542= [HW,SCSI]
  219. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  220. aic7xxx= [HW,SCSI]
  221. See Documentation/scsi/aic7xxx.txt.
  222. aic79xx= [HW,SCSI]
  223. See Documentation/scsi/aic79xx.txt.
  224. amijoy.map= [HW,JOY] Amiga joystick support
  225. Map of devices attached to JOY0DAT and JOY1DAT
  226. Format: <a>,<b>
  227. See also Documentation/kernel/input/joystick.txt
  228. analog.map= [HW,JOY] Analog joystick and gamepad support
  229. Specifies type or capabilities of an analog joystick
  230. connected to one of 16 gameports
  231. Format: <type1>,<type2>,..<type16>
  232. apc= [HW,SPARC]
  233. Power management functions (SPARCstation-4/5 + deriv.)
  234. Format: noidle
  235. Disable APC CPU standby support. SPARCstation-Fox does
  236. not play well with APC CPU idle - disable it if you have
  237. APC and your system crashes randomly.
  238. apic= [APIC,i386] Advanced Programmable Interrupt Controller
  239. Change the output verbosity whilst booting
  240. Format: { quiet (default) | verbose | debug }
  241. Change the amount of debugging information output
  242. when initialising the APIC and IO-APIC components.
  243. apm= [APM] Advanced Power Management
  244. See header of arch/i386/kernel/apm.c.
  245. applicom= [HW]
  246. Format: <mem>,<irq>
  247. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  248. Format: <io>,<irq>,<nodeID>
  249. ataflop= [HW,M68k]
  250. atarimouse= [HW,MOUSE] Atari Mouse
  251. atascsi= [HW,SCSI] Atari SCSI
  252. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  253. EzKey and similar keyboards
  254. atkbd.reset= [HW] Reset keyboard during initialization
  255. atkbd.set= [HW] Select keyboard code set
  256. Format: <int> (2 = AT (default), 3 = PS/2)
  257. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  258. keyboards
  259. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  260. Format: <bool> (0 = real, 1 = synthetic (default))
  261. atkbd.softrepeat= [HW]
  262. Use software keyboard repeat
  263. autotest [IA64]
  264. baycom_epp= [HW,AX25]
  265. Format: <io>,<mode>
  266. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  267. Format: <io>,<mode>
  268. See header of drivers/net/hamradio/baycom_par.c.
  269. baycom_ser_fdx= [HW,AX25]
  270. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  271. Format: <io>,<irq>,<mode>[,<baud>]
  272. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  273. baycom_ser_hdx= [HW,AX25]
  274. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  275. Format: <io>,<irq>,<mode>
  276. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  277. blkmtd_device= [HW,MTD]
  278. blkmtd_erasesz=
  279. blkmtd_ro=
  280. blkmtd_bs=
  281. blkmtd_count=
  282. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  283. bttv.radio= Most important insmod options are available as
  284. kernel args too.
  285. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  286. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  287. BusLogic= [HW,SCSI]
  288. See drivers/scsi/BusLogic.c, comment before function
  289. BusLogic_ParseDriverOptions().
  290. c101= [NET] Moxa C101 synchronous serial card
  291. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  292. Sometimes CPU hardware bugs make them report the cache
  293. size incorrectly. The kernel will attempt work arounds
  294. to fix known problems, but for some CPUs it is not
  295. possible to determine what the correct size should be.
  296. This option provides an override for these situations.
  297. chandev= [HW,NET] Generic channel device initialisation
  298. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  299. Format: { "0" | "1" }
  300. See security/selinux/Kconfig help text.
  301. 0 -- check protection applied by kernel (includes
  302. any implied execute protection).
  303. 1 -- check protection requested by application.
  304. Default value is set via a kernel config option.
  305. Value can be changed at runtime via
  306. /selinux/checkreqprot.
  307. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  308. [Deprecated]
  309. Forces specified clocksource (if available) to be used
  310. when calculating gettimeofday(). If specified
  311. clocksource is not available, it defaults to PIT.
  312. Format: { pit | tsc | cyclone | pmtmr }
  313. clocksource= [GENERIC_TIME] Override the default clocksource
  314. Format: <string>
  315. Override the default clocksource and use the clocksource
  316. with the name specified.
  317. Some clocksource names to choose from, depending on
  318. the platform:
  319. [all] jiffies (this is the base, fallback clocksource)
  320. [ACPI] acpi_pm
  321. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  322. pxa_timer,timer3,32k_counter,timer0_1
  323. [AVR32] avr32
  324. [X86-32] pit,hpet,tsc,vmi-timer;
  325. scx200_hrt on Geode; cyclone on IBM x440
  326. [MIPS] MIPS
  327. [PARISC] cr16
  328. [S390] tod
  329. [SH] SuperH
  330. [SPARC64] tick
  331. [X86-64] hpet,tsc
  332. code_bytes [IA32] How many bytes of object code to print in an
  333. oops report.
  334. Range: 0 - 8192
  335. Default: 64
  336. disable_8254_timer
  337. enable_8254_timer
  338. [IA32/X86_64] Disable/Enable interrupt 0 timer routing
  339. over the 8254 in addition to over the IO-APIC. The
  340. kernel tries to set a sensible default.
  341. hpet= [X86-32,HPET] option to disable HPET and use PIT.
  342. Format: disable
  343. com20020= [HW,NET] ARCnet - COM20020 chipset
  344. Format:
  345. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  346. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  347. Format: <io>[,<irq>]
  348. com90xx= [HW,NET]
  349. ARCnet - COM90xx chipset (memory-mapped buffers)
  350. Format: <io>[,<irq>[,<memstart>]]
  351. condev= [HW,S390] console device
  352. conmode=
  353. console= [KNL] Output console device and options.
  354. tty<n> Use the virtual console device <n>.
  355. ttyS<n>[,options]
  356. ttyUSB0[,options]
  357. Use the specified serial port. The options are of
  358. the form "bbbbpnf", where "bbbb" is the baud rate,
  359. "p" is parity ("n", "o", or "e"), "n" is number of
  360. bits, and "f" is flow control ("r" for RTS or
  361. omit it). Default is "9600n8".
  362. See Documentation/serial-console.txt for more
  363. information. See
  364. Documentation/networking/netconsole.txt for an
  365. alternative.
  366. uart[8250],io,<addr>[,options]
  367. uart[8250],mmio,<addr>[,options]
  368. Start an early, polled-mode console on the 8250/16550
  369. UART at the specified I/O port or MMIO address,
  370. switching to the matching ttyS device later. The
  371. options are the same as for ttyS, above.
  372. earlycon= [KNL] Output early console device and options.
  373. uart[8250],io,<addr>[,options]
  374. uart[8250],mmio,<addr>[,options]
  375. Start an early, polled-mode console on the 8250/16550
  376. UART at the specified I/O port or MMIO address.
  377. The options are the same as for ttyS, above.
  378. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  379. Format:
  380. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  381. cpia_pp= [HW,PPT]
  382. Format: { parport<nr> | auto | none }
  383. crashkernel=nn[KMG]@ss[KMG]
  384. [KNL] Reserve a chunk of physical memory to
  385. hold a kernel to switch to with kexec on panic.
  386. cs4232= [HW,OSS]
  387. Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
  388. cs89x0_dma= [HW,NET]
  389. Format: <dma>
  390. cs89x0_media= [HW,NET]
  391. Format: { rj45 | aui | bnc }
  392. cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
  393. dasd= [HW,NET]
  394. See header of drivers/s390/block/dasd_devmap.c.
  395. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  396. (one device per port)
  397. Format: <port#>,<type>
  398. See also Documentation/input/joystick-parport.txt
  399. debug [KNL] Enable kernel debugging (events log level).
  400. debug_locks_verbose=
  401. [KNL] verbose self-tests
  402. Format=<0|1>
  403. Print debugging info while doing the locking API
  404. self-tests.
  405. We default to 0 (no extra messages), setting it to
  406. 1 will print _a lot_ more information - normally
  407. only useful to kernel developers.
  408. decnet= [HW,NET]
  409. Format: <area>[,<node>]
  410. See also Documentation/networking/decnet.txt.
  411. default_blu= [VT]
  412. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  413. Change the default blue palette of the console.
  414. This is a 16-member array composed of values
  415. ranging from 0-255.
  416. default_grn= [VT]
  417. Format: <green0>,<green1>,<green2>,...,<green15>
  418. Change the default green palette of the console.
  419. This is a 16-member array composed of values
  420. ranging from 0-255.
  421. default_red= [VT]
  422. Format: <red0>,<red1>,<red2>,...,<red15>
  423. Change the default red palette of the console.
  424. This is a 16-member array composed of values
  425. ranging from 0-255.
  426. default_utf8= [VT]
  427. Format=<0|1>
  428. Set system-wide default UTF-8 mode for all tty's.
  429. Default is 0 and by setting to 1, it enables UTF-8
  430. mode for all newly opened or allocated terminals.
  431. dhash_entries= [KNL]
  432. Set number of hash buckets for dentry cache.
  433. digi= [HW,SERIAL]
  434. IO parameters + enable/disable command.
  435. digiepca= [HW,SERIAL]
  436. See drivers/char/README.epca and
  437. Documentation/digiepca.txt.
  438. dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
  439. support available.
  440. Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
  441. dmasound= [HW,OSS] Sound subsystem buffers
  442. dscc4.setup= [NET]
  443. dtc3181e= [HW,SCSI]
  444. earlyprintk= [X86-32,X86-64,SH]
  445. earlyprintk=vga
  446. earlyprintk=serial[,ttySn[,baudrate]]
  447. Append ",keep" to not disable it when the real console
  448. takes over.
  449. Only vga or serial at a time, not both.
  450. Currently only ttyS0 and ttyS1 are supported.
  451. Interaction with the standard serial driver is not
  452. very good.
  453. The VGA output is eventually overwritten by the real
  454. console.
  455. eata= [HW,SCSI]
  456. ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
  457. Format: <int>
  458. 0: polling mode
  459. non-0: interrupt mode (default)
  460. eda= [HW,PS2]
  461. edb= [HW,PS2]
  462. edd= [EDD]
  463. Format: {"of[f]" | "sk[ipmbr]"}
  464. See comment in arch/i386/boot/edd.S
  465. eicon= [HW,ISDN]
  466. Format: <id>,<membase>,<irq>
  467. eisa_irq_edge= [PARISC,HW]
  468. See header of drivers/parisc/eisa.c.
  469. elanfreq= [X86-32]
  470. See comment before function elanfreq_setup() in
  471. arch/i386/kernel/cpu/cpufreq/elanfreq.c.
  472. elevator= [IOSCHED]
  473. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  474. See Documentation/block/as-iosched.txt and
  475. Documentation/block/deadline-iosched.txt for details.
  476. elfcorehdr= [X86-32, X86_64]
  477. Specifies physical address of start of kernel core
  478. image elf header. Generally kexec loader will
  479. pass this option to capture kernel.
  480. See Documentation/kdump/kdump.txt for details.
  481. enforcing [SELINUX] Set initial enforcing status.
  482. Format: {"0" | "1"}
  483. See security/selinux/Kconfig help text.
  484. 0 -- permissive (log only, no denials).
  485. 1 -- enforcing (deny and log).
  486. Default value is 0.
  487. Value can be changed at runtime via /selinux/enforce.
  488. es1371= [HW,OSS]
  489. Format: <spdif>,[<nomix>,[<amplifier>]]
  490. See also header of sound/oss/es1371.c.
  491. ether= [HW,NET] Ethernet cards parameters
  492. This option is obsoleted by the "netdev=" option, which
  493. has equivalent usage. See its documentation for details.
  494. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  495. Format: <io>[,<irq>]
  496. failslab=
  497. fail_page_alloc=
  498. fail_make_request=[KNL]
  499. General fault injection mechanism.
  500. Format: <interval>,<probability>,<space>,<times>
  501. See also /Documentation/fault-injection/.
  502. fd_mcs= [HW,SCSI]
  503. See header of drivers/scsi/fd_mcs.c.
  504. fdomain= [HW,SCSI]
  505. See header of drivers/scsi/fdomain.c.
  506. floppy= [HW]
  507. See Documentation/floppy.txt.
  508. gamecon.map[2|3]=
  509. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  510. support via parallel port (up to 5 devices per port)
  511. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  512. See also Documentation/input/joystick-parport.txt
  513. gamma= [HW,DRM]
  514. gdth= [HW,SCSI]
  515. See header of drivers/scsi/gdth.c.
  516. gpt [EFI] Forces disk with valid GPT signature but
  517. invalid Protective MBR to be treated as GPT.
  518. gvp11= [HW,SCSI]
  519. hashdist= [KNL,NUMA] Large hashes allocated during boot
  520. are distributed across NUMA nodes. Defaults on
  521. for IA-64, off otherwise.
  522. Format: 0 | 1 (for off | on)
  523. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  524. hd= [EIDE] (E)IDE hard drive subsystem geometry
  525. Format: <cyl>,<head>,<sect>
  526. hd?= [HW] (E)IDE subsystem
  527. hd?lun= See Documentation/ide.txt.
  528. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  529. size of <nn>. This works even on boxes that have no
  530. highmem otherwise. This also works to reduce highmem
  531. size on bigger boxes.
  532. highres= [KNL] Enable/disable high resolution timer mode.
  533. Valid parameters: "on", "off"
  534. Default: "on"
  535. hisax= [HW,ISDN]
  536. See Documentation/isdn/README.HiSax.
  537. hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
  538. i8042.direct [HW] Put keyboard port into non-translated mode
  539. i8042.dumbkbd [HW] Pretend that controller can only read data from
  540. keyboard and cannot control its state
  541. (Don't attempt to blink the leds)
  542. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  543. i8042.nokbd [HW] Don't check/create keyboard port
  544. i8042.nomux [HW] Don't check presence of an active multiplexing
  545. controller
  546. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  547. controllers
  548. i8042.panicblink=
  549. [HW] Frequency with which keyboard LEDs should blink
  550. when kernel panics (default is 0.5 sec)
  551. i8042.reset [HW] Reset the controller during init and cleanup
  552. i8042.unlock [HW] Unlock (ignore) the keylock
  553. i810= [HW,DRM]
  554. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  555. indicates that the driver is running on unsupported
  556. hardware.
  557. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  558. does not match list of supported models.
  559. i8k.power_status
  560. [HW] Report power status in /proc/i8k
  561. (disabled by default)
  562. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  563. capability is set.
  564. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  565. See Documentation/mca.txt.
  566. icn= [HW,ISDN]
  567. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  568. ide= [HW] (E)IDE subsystem
  569. Format: ide=nodma or ide=doubler or ide=reverse
  570. See Documentation/ide.txt.
  571. ide?= [HW] (E)IDE subsystem
  572. Format: ide?=noprobe or chipset specific parameters.
  573. See Documentation/ide.txt.
  574. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  575. See Documentation/ide.txt.
  576. idle= [X86]
  577. Format: idle=poll or idle=mwait
  578. Poll forces a polling idle loop that can slightly improves the performance
  579. of waking up a idle CPU, but will use a lot of power and make the system
  580. run hot. Not recommended.
  581. idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
  582. to not use it because it doesn't save as much power as a normal idle
  583. loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
  584. as idle=poll.
  585. ignore_loglevel [KNL]
  586. Ignore loglevel setting - this will print /all/
  587. kernel messages to the console. Useful for debugging.
  588. ihash_entries= [KNL]
  589. Set number of hash buckets for inode cache.
  590. in2000= [HW,SCSI]
  591. See header of drivers/scsi/in2000.c.
  592. init= [KNL]
  593. Format: <full_path>
  594. Run specified binary instead of /sbin/init as init
  595. process.
  596. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  597. for working out where the kernel is dying during
  598. startup.
  599. initrd= [BOOT] Specify the location of the initial ramdisk
  600. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  601. Format: <irq>
  602. inttest= [IA64]
  603. io7= [HW] IO7 for Marvel based alpha systems
  604. See comment before marvel_specify_io7 in
  605. arch/alpha/kernel/core_marvel.c.
  606. ip= [IP_PNP]
  607. See Documentation/nfsroot.txt.
  608. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  609. See comment before ip2_setup() in
  610. drivers/char/ip2/ip2base.c.
  611. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  612. See header of drivers/scsi/ips.c.
  613. ports= [IP_VS_FTP] IPVS ftp helper module
  614. Default is 21.
  615. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  616. may be specified.
  617. Format: <port>,<port>....
  618. irqfixup [HW]
  619. When an interrupt is not handled search all handlers
  620. for it. Intended to get systems with badly broken
  621. firmware running.
  622. irqpoll [HW]
  623. When an interrupt is not handled search all handlers
  624. for it. Also check all handlers each timer
  625. interrupt. Intended to get systems with badly broken
  626. firmware running.
  627. isapnp= [ISAPNP]
  628. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  629. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  630. Format:
  631. <cpu number>,...,<cpu number>
  632. or
  633. <cpu number>-<cpu number> (must be a positive range in ascending order)
  634. or a mixture
  635. <cpu number>,...,<cpu number>-<cpu number>
  636. This option can be used to specify one or more CPUs
  637. to isolate from the general SMP balancing and scheduling
  638. algorithms. The only way to move a process onto or off
  639. an "isolated" CPU is via the CPU affinity syscalls.
  640. <cpu number> begins at 0 and the maximum value is
  641. "number of CPUs in system - 1".
  642. This option is the preferred way to isolate CPUs. The
  643. alternative -- manually setting the CPU mask of all
  644. tasks in the system -- can cause problems and
  645. suboptimal load balancer performance.
  646. iucv= [HW,NET]
  647. js= [HW,JOY] Analog joystick
  648. See Documentation/input/joystick.txt.
  649. kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  650. specifies the amount of memory usable by the kernel
  651. for non-movable allocations. The requested amount is
  652. spread evenly throughout all nodes in the system. The
  653. remaining memory in each node is used for Movable
  654. pages. In the event, a node is too small to have both
  655. kernelcore and Movable pages, kernelcore pages will
  656. take priority and other nodes will have a larger number
  657. of kernelcore pages. The Movable zone is used for the
  658. allocation of pages that may be reclaimed or moved
  659. by the page migration subsystem. This means that
  660. HugeTLB pages may not be allocated from this zone.
  661. Note that allocations like PTEs-from-HighMem still
  662. use the HighMem zone if it exists, and the Normal
  663. zone if it does not.
  664. movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  665. is similar to kernelcore except it specifies the
  666. amount of memory used for migratable allocations.
  667. If both kernelcore and movablecore is specified,
  668. then kernelcore will be at *least* the specified
  669. value but may be more. If movablecore on its own
  670. is specified, the administrator must be careful
  671. that the amount of memory usable for all allocations
  672. is not too small.
  673. keepinitrd [HW,ARM]
  674. kstack=N [X86-32,X86-64] Print N words from the kernel stack
  675. in oops dumps.
  676. l2cr= [PPC]
  677. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  678. disabled it.
  679. lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
  680. C2 power state.
  681. lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
  682. Format: addr:<io>,irq:<irq>
  683. load_ramdisk= [RAM] List of ramdisks to load from floppy
  684. See Documentation/ramdisk.txt.
  685. lockd.nlm_grace_period=P [NFS] Assign grace period.
  686. Format: <integer>
  687. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  688. Format: <integer>
  689. lockd.nlm_timeout=T [NFS] Assign timeout value.
  690. Format: <integer>
  691. lockd.nlm_udpport=M [NFS] Assign UDP port.
  692. Format: <integer>
  693. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  694. Format: <irq>
  695. loglevel= All Kernel Messages with a loglevel smaller than the
  696. console loglevel will be printed to the console. It can
  697. also be changed with klogd or other programs. The
  698. loglevels are defined as follows:
  699. 0 (KERN_EMERG) system is unusable
  700. 1 (KERN_ALERT) action must be taken immediately
  701. 2 (KERN_CRIT) critical conditions
  702. 3 (KERN_ERR) error conditions
  703. 4 (KERN_WARNING) warning conditions
  704. 5 (KERN_NOTICE) normal but significant condition
  705. 6 (KERN_INFO) informational
  706. 7 (KERN_DEBUG) debug-level messages
  707. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  708. Format: { n | nk | nM }
  709. n must be a power of two. The default size
  710. is set in the kernel config file.
  711. lp=0 [LP] Specify parallel ports to use, e.g,
  712. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  713. lp=reset first parallel port). 'lp=0' disables the
  714. lp=auto printer driver. 'lp=reset' (which can be
  715. specified in addition to the ports) causes
  716. attached printers to be reset. Using
  717. lp=port1,port2,... specifies the parallel ports
  718. to associate lp devices with, starting with
  719. lp0. A port specification may be 'none' to skip
  720. that lp device, or a parport name such as
  721. 'parport0'. Specifying 'lp=auto' instead of a
  722. port specification list means that device IDs
  723. from each port should be examined, to see if
  724. an IEEE 1284-compliant printer is attached; if
  725. so, the driver will manage that printer.
  726. See also header of drivers/char/lp.c.
  727. lpj=n [KNL]
  728. Sets loops_per_jiffy to given constant, thus avoiding
  729. time-consuming boot-time autodetection (up to 250 ms per
  730. CPU). 0 enables autodetection (default). To determine
  731. the correct value for your kernel, boot with normal
  732. autodetection and see what value is printed. Note that
  733. on SMP systems the preset will be applied to all CPUs,
  734. which is likely to cause problems if your CPUs need
  735. significantly divergent settings. An incorrect value
  736. will cause delays in the kernel to be wrong, leading to
  737. unpredictable I/O errors and other breakage. Although
  738. unlikely, in the extreme case this might damage your
  739. hardware.
  740. ltpc= [NET]
  741. Format: <io>,<irq>,<dma>
  742. mac5380= [HW,SCSI] Format:
  743. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  744. mac53c9x= [HW,SCSI] Format:
  745. <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  746. machvec= [IA64] Force the use of a particular machine-vector
  747. (machvec) in a generic kernel.
  748. Example: machvec=hpzx1_swiotlb
  749. max_loop= [LOOP] Maximum number of loopback devices that can
  750. be mounted
  751. Format: <1-256>
  752. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  753. should make use of.
  754. Using "nosmp" or "maxcpus=0" will disable SMP
  755. entirely (the MPS table probe still happens, though).
  756. A command-line option of "maxcpus=<NUM>", where <NUM>
  757. is an integer greater than 0, limits the maximum number
  758. of CPUs activated in SMP mode to <NUM>.
  759. Using "maxcpus=1" on an SMP kernel is the trivial
  760. case of an SMP kernel with only one CPU.
  761. max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
  762. equal to this physical address is ignored.
  763. max_luns= [SCSI] Maximum number of LUNs to probe.
  764. Should be between 1 and 2^32-1.
  765. max_report_luns=
  766. [SCSI] Maximum number of LUNs received.
  767. Should be between 1 and 16384.
  768. mca-pentium [BUGS=X86-32]
  769. mcatest= [IA-64]
  770. mce [X86-32] Machine Check Exception
  771. md= [HW] RAID subsystems devices and level
  772. See Documentation/md.txt.
  773. mdacon= [MDA]
  774. Format: <first>,<last>
  775. Specifies range of consoles to be captured by the MDA.
  776. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  777. Amount of memory to be used when the kernel is not able
  778. to see the whole system memory or for test.
  779. [X86-32] Use together with memmap= to avoid physical
  780. address space collisions. Without memmap= PCI devices
  781. could be placed at addresses belonging to unused RAM.
  782. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  783. memory.
  784. memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
  785. E820 memory map, as specified by the user.
  786. Such memmap=exactmap lines can be constructed based on
  787. BIOS output or other requirements. See the memmap=nn@ss
  788. option description.
  789. memmap=nn[KMG]@ss[KMG]
  790. [KNL] Force usage of a specific region of memory
  791. Region of memory to be used, from ss to ss+nn.
  792. memmap=nn[KMG]#ss[KMG]
  793. [KNL,ACPI] Mark specific memory as ACPI data.
  794. Region of memory to be used, from ss to ss+nn.
  795. memmap=nn[KMG]$ss[KMG]
  796. [KNL,ACPI] Mark specific memory as reserved.
  797. Region of memory to be used, from ss to ss+nn.
  798. meye.*= [HW] Set MotionEye Camera parameters
  799. See Documentation/video4linux/meye.txt.
  800. mga= [HW,DRM]
  801. mousedev.tap_time=
  802. [MOUSE] Maximum time between finger touching and
  803. leaving touchpad surface for touch to be considered
  804. a tap and be reported as a left button click (for
  805. touchpads working in absolute mode only).
  806. Format: <msecs>
  807. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  808. reporting absolute coordinates, such as tablets
  809. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  810. reporting absolute coordinates, such as tablets
  811. mpu401= [HW,OSS]
  812. Format: <io>,<irq>
  813. MTD_Partition= [MTD]
  814. Format: <name>,<region-number>,<size>,<offset>
  815. MTD_Region= [MTD] Format:
  816. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  817. mtdparts= [MTD]
  818. See drivers/mtd/cmdlinepart.c.
  819. mtouchusb.raw_coordinates=
  820. [HW] Make the MicroTouch USB driver use raw coordinates
  821. ('y', default) or cooked coordinates ('n')
  822. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  823. NCR_D700= [HW,SCSI]
  824. See header of drivers/scsi/NCR_D700.c.
  825. ncr5380= [HW,SCSI]
  826. ncr53c400= [HW,SCSI]
  827. ncr53c400a= [HW,SCSI]
  828. ncr53c406a= [HW,SCSI]
  829. ncr53c8xx= [HW,SCSI]
  830. netdev= [NET] Network devices parameters
  831. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  832. Note that mem_start is often overloaded to mean
  833. something different and driver-specific.
  834. This usage is only documented in each driver source
  835. file if at all.
  836. nfsaddrs= [NFS]
  837. See Documentation/nfsroot.txt.
  838. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  839. See Documentation/nfsroot.txt.
  840. nfs.callback_tcpport=
  841. [NFS] set the TCP port on which the NFSv4 callback
  842. channel should listen.
  843. nfs.idmap_cache_timeout=
  844. [NFS] set the maximum lifetime for idmapper cache
  845. entries.
  846. nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
  847. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  848. emulation library even if a 387 maths coprocessor
  849. is present.
  850. noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  851. when set.
  852. Format: <int>
  853. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  854. caches in the slab allocator. Saves per-node memory,
  855. but will impact performance.
  856. noalign [KNL,ARM]
  857. noapic [SMP,APIC] Tells the kernel to not make use of any
  858. IOAPICs that may be present in the system.
  859. noasync [HW,M68K] Disables async and sync negotiation for
  860. all devices.
  861. nobats [PPC] Do not use BATs for mapping kernel lowmem
  862. on "Classic" PPC cores.
  863. nocache [ARM]
  864. nodelayacct [KNL] Disable per-task delay accounting
  865. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  866. noexec [IA-64]
  867. noexec [X86-32,X86-64]
  868. noexec=on: enable non-executable mappings (default)
  869. noexec=off: disable nn-executable mappings
  870. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  871. register save and restore. The kernel will only save
  872. legacy floating-point registers on task switch.
  873. nohlt [BUGS=ARM]
  874. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  875. instruction doesn't work correctly and not to
  876. use it.
  877. nohalt [IA-64] Tells the kernel not to use the power saving
  878. function PAL_HALT_LIGHT when idle. This increases
  879. power-consumption. On the positive side, it reduces
  880. interrupt wake-up latency, which may improve performance
  881. in certain environments such as networked servers or
  882. real-time systems.
  883. nohz= [KNL] Boottime enable/disable dynamic ticks
  884. Valid arguments: on, off
  885. Default: on
  886. noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
  887. noirqdebug [X86-32] Disables the code which attempts to detect and
  888. disable unhandled interrupt sources.
  889. no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
  890. broken timer IRQ sources.
  891. noisapnp [ISAPNP] Disables ISA PnP code.
  892. noinitrd [RAM] Tells the kernel not to load any configured
  893. initial RAM disk.
  894. nointroute [IA-64]
  895. nojitter [IA64] Disables jitter checking for ITC timers.
  896. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  897. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  898. noltlbs [PPC] Do not use large page/tlb entries for kernel
  899. lowmem mapping on PPC40x.
  900. nomca [IA-64] Disable machine check abort handling
  901. nomce [X86-32] Machine Check Exception
  902. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  903. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  904. with UP alternatives
  905. noresidual [PPC] Don't use residual data on PReP machines.
  906. noresume [SWSUSP] Disables resume and restores original swap
  907. space.
  908. no-scroll [VGA] Disables scrollback.
  909. This is required for the Braillex ib80-piezo Braille
  910. reader made by F.H. Papenmeier (Germany).
  911. nosbagart [IA-64]
  912. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  913. nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
  914. nosoftlockup [KNL] Disable the soft-lockup detector.
  915. nosync [HW,M68K] Disables sync negotiation for all devices.
  916. notsc [BUGS=X86-32] Disable Time Stamp Counter
  917. nousb [USB] Disable the USB subsystem
  918. nowb [ARM]
  919. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  920. one of ['zone', 'node', 'default'] can be specified
  921. This can be set from sysctl after boot.
  922. See Documentation/sysctl/vm.txt for details.
  923. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  924. opl3= [HW,OSS]
  925. Format: <io>
  926. oprofile.timer= [HW]
  927. Use timer interrupt instead of performance counters
  928. osst= [HW,SCSI] SCSI Tape Driver
  929. Format: <buffer_size>,<write_threshold>
  930. See also Documentation/scsi/st.txt.
  931. panic= [KNL] Kernel behaviour on panic
  932. Format: <timeout>
  933. parkbd.port= [HW] Parallel port number the keyboard adapter is
  934. connected to, default is 0.
  935. Format: <parport#>
  936. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  937. 0 for XT, 1 for AT (default is AT).
  938. Format: <mode>
  939. parport= [HW,PPT] Specify parallel ports. 0 disables.
  940. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  941. Use 'auto' to force the driver to use any
  942. IRQ/DMA settings detected (the default is to
  943. ignore detected IRQ/DMA settings because of
  944. possible conflicts). You can specify the base
  945. address, IRQ, and DMA settings; IRQ and DMA
  946. should be numbers, or 'auto' (for using detected
  947. settings on that particular port), or 'nofifo'
  948. (to avoid using a FIFO even if it is detected).
  949. Parallel ports are assigned in the order they
  950. are specified on the command line, starting
  951. with parport0.
  952. parport_init_mode= [HW,PPT]
  953. Configure VIA parallel port to operate in
  954. a specific mode. This is necessary on Pegasos
  955. computer where firmware has no options for setting
  956. up parallel port mode and sets it to spp.
  957. Currently this function knows 686a and 8231 chips.
  958. Format: [spp|ps2|epp|ecp|ecpepp]
  959. pas2= [HW,OSS] Format:
  960. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  961. pas16= [HW,SCSI]
  962. See header of drivers/scsi/pas16.c.
  963. pause_on_oops=
  964. Halt all CPUs after the first oops has been printed for
  965. the specified number of seconds. This is to be used if
  966. your oopses keep scrolling off the screen.
  967. pcbit= [HW,ISDN]
  968. pcd. [PARIDE]
  969. See header of drivers/block/paride/pcd.c.
  970. See also Documentation/paride.txt.
  971. pci=option[,option...] [PCI] various PCI subsystem options:
  972. off [X86-32] don't probe for the PCI bus
  973. bios [X86-32] force use of PCI BIOS, don't access
  974. the hardware directly. Use this if your machine
  975. has a non-standard PCI host bridge.
  976. nobios [X86-32] disallow use of PCI BIOS, only direct
  977. hardware access methods are allowed. Use this
  978. if you experience crashes upon bootup and you
  979. suspect they are caused by the BIOS.
  980. conf1 [X86-32] Force use of PCI Configuration
  981. Mechanism 1.
  982. conf2 [X86-32] Force use of PCI Configuration
  983. Mechanism 2.
  984. nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
  985. Configuration
  986. nomsi [MSI] If the PCI_MSI kernel config parameter is
  987. enabled, this kernel boot option can be used to
  988. disable the use of MSI interrupts system-wide.
  989. nosort [X86-32] Don't sort PCI devices according to
  990. order given by the PCI BIOS. This sorting is
  991. done to get a device order compatible with
  992. older kernels.
  993. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  994. routing table. These calls are known to be buggy
  995. on several machines and they hang the machine
  996. when used, but on other computers it's the only
  997. way to get the interrupt routing table. Try
  998. this option if the kernel is unable to allocate
  999. IRQs or discover secondary PCI buses on your
  1000. motherboard.
  1001. rom [X86-32] Assign address space to expansion ROMs.
  1002. Use with caution as certain devices share
  1003. address decoders between ROMs and other
  1004. resources.
  1005. irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
  1006. assigned automatically to PCI devices. You can
  1007. make the kernel exclude IRQs of your ISA cards
  1008. this way.
  1009. pirqaddr=0xAAAAA [X86-32] Specify the physical address
  1010. of the PIRQ table (normally generated
  1011. by the BIOS) if it is outside the
  1012. F0000h-100000h range.
  1013. lastbus=N [X86-32] Scan all buses thru bus #N. Can be
  1014. useful if the kernel is unable to find your
  1015. secondary buses and you want to tell it
  1016. explicitly which ones they are.
  1017. assign-busses [X86-32] Always assign all PCI bus
  1018. numbers ourselves, overriding
  1019. whatever the firmware may have done.
  1020. usepirqmask [X86-32] Honor the possible IRQ mask stored
  1021. in the BIOS $PIR table. This is needed on
  1022. some systems with broken BIOSes, notably
  1023. some HP Pavilion N5400 and Omnibook XE3
  1024. notebooks. This will have no effect if ACPI
  1025. IRQ routing is enabled.
  1026. noacpi [X86-32] Do not use ACPI for IRQ routing
  1027. or for PCI scanning.
  1028. routeirq Do IRQ routing for all PCI devices.
  1029. This is normally done in pci_enable_device(),
  1030. so this option is a temporary workaround
  1031. for broken drivers that don't call it.
  1032. firmware [ARM] Do not re-enumerate the bus but instead
  1033. just use the configuration from the
  1034. bootloader. This is currently used on
  1035. IXP2000 systems where the bus has to be
  1036. configured a certain way for adjunct CPUs.
  1037. noearly [X86] Don't do any early type 1 scanning.
  1038. This might help on some broken boards which
  1039. machine check when some devices' config space
  1040. is read. But various workarounds are disabled
  1041. and some IOMMU drivers will not work.
  1042. bfsort Sort PCI devices into breadth-first order.
  1043. This sorting is done to get a device
  1044. order compatible with older (<= 2.4) kernels.
  1045. nobfsort Don't sort PCI devices into breadth-first order.
  1046. cbiosize=nn[KMG] The fixed amount of bus space which is
  1047. reserved for the CardBus bridge's IO window.
  1048. The default value is 256 bytes.
  1049. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1050. reserved for the CardBus bridge's memory
  1051. window. The default value is 64 megabytes.
  1052. pcmv= [HW,PCMCIA] BadgePAD 4
  1053. pd. [PARIDE]
  1054. See Documentation/paride.txt.
  1055. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1056. boot time.
  1057. Format: { 0 | 1 }
  1058. See arch/parisc/kernel/pdc_chassis.c
  1059. pf. [PARIDE]
  1060. See Documentation/paride.txt.
  1061. pg. [PARIDE]
  1062. See Documentation/paride.txt.
  1063. pirq= [SMP,APIC] Manual mp-table setup
  1064. See Documentation/i386/IO-APIC.txt.
  1065. plip= [PPT,NET] Parallel port network link
  1066. Format: { parport<nr> | timid | 0 }
  1067. See also Documentation/parport.txt.
  1068. pnpacpi= [ACPI]
  1069. { off }
  1070. pnpbios= [ISAPNP]
  1071. { on | off | curr | res | no-curr | no-res }
  1072. pnp_reserve_irq=
  1073. [ISAPNP] Exclude IRQs for the autoconfiguration
  1074. pnp_reserve_dma=
  1075. [ISAPNP] Exclude DMAs for the autoconfiguration
  1076. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1077. Ranges are in pairs (I/O port base and size).
  1078. pnp_reserve_mem=
  1079. [ISAPNP] Exclude memory regions for the
  1080. autoconfiguration.
  1081. Ranges are in pairs (memory base and size).
  1082. print-fatal-signals=
  1083. [KNL] debug: print fatal signals
  1084. print-fatal-signals=1: print segfault info to
  1085. the kernel console.
  1086. default: off.
  1087. printk.time= Show timing data prefixed to each printk message line
  1088. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1089. profile= [KNL] Enable kernel profiling via /proc/profile
  1090. Format: [schedule,]<number>
  1091. Param: "schedule" - profile schedule points.
  1092. Param: <number> - step/bucket size as a power of 2 for
  1093. statistical time based profiling.
  1094. Param: "sleep" - profile D-state sleeping (millisecs)
  1095. processor.max_cstate= [HW,ACPI]
  1096. Limit processor to maximum C-state
  1097. max_cstate=9 overrides any DMI blacklist limit.
  1098. processor.nocst [HW,ACPI]
  1099. Ignore the _CST method to determine C-states,
  1100. instead using the legacy FADT method
  1101. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1102. before loading.
  1103. See Documentation/ramdisk.txt.
  1104. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1105. probe for; one of (bare|imps|exps|lifebook|any).
  1106. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1107. per second.
  1108. psmouse.resetafter= [HW,MOUSE]
  1109. Try to reset the device after so many bad packets
  1110. (0 = never).
  1111. psmouse.resolution=
  1112. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1113. psmouse.smartscroll=
  1114. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1115. 0 = disabled, 1 = enabled (default).
  1116. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1117. Format:
  1118. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1119. pt. [PARIDE]
  1120. See Documentation/paride.txt.
  1121. quiet [KNL] Disable most log messages
  1122. r128= [HW,DRM]
  1123. raid= [HW,RAID]
  1124. See Documentation/md.txt.
  1125. ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
  1126. See Documentation/ramdisk.txt.
  1127. ramdisk_blocksize= [RAM]
  1128. See Documentation/ramdisk.txt.
  1129. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1130. New name for the ramdisk parameter.
  1131. See Documentation/ramdisk.txt.
  1132. rcu.blimit= [KNL,BOOT] Set maximum number of finished
  1133. RCU callbacks to process in one batch.
  1134. rcu.qhimark= [KNL,BOOT] Set threshold of queued
  1135. RCU callbacks over which batch limiting is disabled.
  1136. rcu.qlowmark= [KNL,BOOT] Set threshold of queued
  1137. RCU callbacks below which batch limiting is re-enabled.
  1138. rdinit= [KNL]
  1139. Format: <full_path>
  1140. Run specified binary instead of /init from the ramdisk,
  1141. used for early userspace startup. See initrd.
  1142. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1143. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1144. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1145. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1146. reservetop= [X86-32]
  1147. Format: nn[KMG]
  1148. Reserves a hole at the top of the kernel virtual
  1149. address space.
  1150. reset_devices [KNL] Force drivers to reset the underlying device
  1151. during initialization.
  1152. resume= [SWSUSP]
  1153. Specify the partition device for software suspend
  1154. resume_offset= [SWSUSP]
  1155. Specify the offset from the beginning of the partition
  1156. given by "resume=" at which the swap header is located,
  1157. in <PAGE_SIZE> units (needed only for swap files).
  1158. See Documentation/power/swsusp-and-swap-files.txt
  1159. retain_initrd [RAM] Keep initrd memory after extraction
  1160. rhash_entries= [KNL,NET]
  1161. Set number of hash buckets for route cache
  1162. riscom8= [HW,SERIAL]
  1163. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1164. ro [KNL] Mount root device read-only on boot
  1165. root= [KNL] Root filesystem
  1166. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1167. mount the root filesystem
  1168. rootflags= [KNL] Set root filesystem mount option string
  1169. rootfstype= [KNL] Set root filesystem type
  1170. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1171. Useful for devices that are detected asynchronously
  1172. (e.g. USB and MMC devices).
  1173. rw [KNL] Mount root device read-write on boot
  1174. S [KNL] Run init in single mode
  1175. sa1100ir [NET]
  1176. See drivers/net/irda/sa1100_ir.c.
  1177. sb= [HW,OSS]
  1178. Format: <io>,<irq>,<dma>,<dma2>
  1179. sbni= [NET] Granch SBNI12 leased line adapter
  1180. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1181. Format: <io>[,<timeout>[,<isapnp>]]
  1182. scsi_debug_*= [SCSI]
  1183. See drivers/scsi/scsi_debug.c.
  1184. scsi_default_dev_flags=
  1185. [SCSI] SCSI default device flags
  1186. Format: <integer>
  1187. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1188. Format: <vendor>:<model>:<flags>
  1189. (flags are integer value)
  1190. scsi_logging= [SCSI]
  1191. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1192. discovered. async scans them in kernel threads,
  1193. allowing boot to proceed. none ignores them, expecting
  1194. user space to do the scan.
  1195. selinux [SELINUX] Disable or enable SELinux at boot time.
  1196. Format: { "0" | "1" }
  1197. See security/selinux/Kconfig help text.
  1198. 0 -- disable.
  1199. 1 -- enable.
  1200. Default value is set via kernel config option.
  1201. If enabled at boot time, /selinux/disable can be used
  1202. later to disable prior to initial policy load.
  1203. selinux_compat_net =
  1204. [SELINUX] Set initial selinux_compat_net flag value.
  1205. Format: { "0" | "1" }
  1206. 0 -- use new secmark-based packet controls
  1207. 1 -- use legacy packet controls
  1208. Default value is 0 (preferred).
  1209. Value can be changed at runtime via
  1210. /selinux/compat_net.
  1211. serialnumber [BUGS=X86-32]
  1212. sg_def_reserved_size= [SCSI]
  1213. shapers= [NET]
  1214. Maximal number of shapers.
  1215. sim710= [SCSI,HW]
  1216. See header of drivers/scsi/sim710.c.
  1217. simeth= [IA-64]
  1218. simscsi=
  1219. slram= [HW,MTD]
  1220. slub_debug[=options[,slabs]] [MM, SLUB]
  1221. Enabling slub_debug allows one to determine the
  1222. culprit if slab objects become corrupted. Enabling
  1223. slub_debug can create guard zones around objects and
  1224. may poison objects when not in use. Also tracks the
  1225. last alloc / free. For more information see
  1226. Documentation/vm/slub.txt.
  1227. slub_max_order= [MM, SLUB]
  1228. Determines the maximum allowed order for slabs.
  1229. A high setting may cause OOMs due to memory
  1230. fragmentation. For more information see
  1231. Documentation/vm/slub.txt.
  1232. slub_min_objects= [MM, SLUB]
  1233. The minimum number of objects per slab. SLUB will
  1234. increase the slab order up to slub_max_order to
  1235. generate a sufficiently large slab able to contain
  1236. the number of objects indicated. The higher the number
  1237. of objects the smaller the overhead of tracking slabs
  1238. and the less frequently locks need to be acquired.
  1239. For more information see Documentation/vm/slub.txt.
  1240. slub_min_order= [MM, SLUB]
  1241. Determines the mininum page order for slabs. Must be
  1242. lower than slub_max_order.
  1243. For more information see Documentation/vm/slub.txt.
  1244. slub_nomerge [MM, SLUB]
  1245. Disable merging of slabs with similar size. May be
  1246. necessary if there is some reason to distinguish
  1247. allocs to different slabs. Debug options disable
  1248. merging on their own.
  1249. For more information see Documentation/vm/slub.txt.
  1250. smart2= [HW]
  1251. Format: <io1>[,<io2>[,...,<io8>]]
  1252. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1253. attempt to substitute SMP alternatives once at boot.
  1254. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1255. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1256. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1257. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1258. smsc-ircc2.ircc_irq= [HW] IRQ line
  1259. smsc-ircc2.ircc_dma= [HW] DMA channel
  1260. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1261. 0: Toshiba Satellite 1800 (GP data pin select)
  1262. 1: Fast pin select (default)
  1263. 2: ATC IRMode
  1264. snd-ad1816a= [HW,ALSA]
  1265. snd-ad1848= [HW,ALSA]
  1266. snd-ali5451= [HW,ALSA]
  1267. snd-als100= [HW,ALSA]
  1268. snd-als4000= [HW,ALSA]
  1269. snd-azt2320= [HW,ALSA]
  1270. snd-cmi8330= [HW,ALSA]
  1271. snd-cmipci= [HW,ALSA]
  1272. snd-cs4231= [HW,ALSA]
  1273. snd-cs4232= [HW,ALSA]
  1274. snd-cs4236= [HW,ALSA]
  1275. snd-cs4281= [HW,ALSA]
  1276. snd-cs46xx= [HW,ALSA]
  1277. snd-dt019x= [HW,ALSA]
  1278. snd-dummy= [HW,ALSA]
  1279. snd-emu10k1= [HW,ALSA]
  1280. snd-ens1370= [HW,ALSA]
  1281. snd-ens1371= [HW,ALSA]
  1282. snd-es968= [HW,ALSA]
  1283. snd-es1688= [HW,ALSA]
  1284. snd-es18xx= [HW,ALSA]
  1285. snd-es1938= [HW,ALSA]
  1286. snd-es1968= [HW,ALSA]
  1287. snd-fm801= [HW,ALSA]
  1288. snd-gusclassic= [HW,ALSA]
  1289. snd-gusextreme= [HW,ALSA]
  1290. snd-gusmax= [HW,ALSA]
  1291. snd-hdsp= [HW,ALSA]
  1292. snd-ice1712= [HW,ALSA]
  1293. snd-intel8x0= [HW,ALSA]
  1294. snd-interwave= [HW,ALSA]
  1295. snd-interwave-stb=
  1296. [HW,ALSA]
  1297. snd-korg1212= [HW,ALSA]
  1298. snd-maestro3= [HW,ALSA]
  1299. snd-mpu401= [HW,ALSA]
  1300. snd-mtpav= [HW,ALSA]
  1301. snd-nm256= [HW,ALSA]
  1302. snd-opl3sa2= [HW,ALSA]
  1303. snd-opti92x-ad1848=
  1304. [HW,ALSA]
  1305. snd-opti92x-cs4231=
  1306. [HW,ALSA]
  1307. snd-opti93x= [HW,ALSA]
  1308. snd-pmac= [HW,ALSA]
  1309. snd-rme32= [HW,ALSA]
  1310. snd-rme96= [HW,ALSA]
  1311. snd-rme9652= [HW,ALSA]
  1312. snd-sb8= [HW,ALSA]
  1313. snd-sb16= [HW,ALSA]
  1314. snd-sbawe= [HW,ALSA]
  1315. snd-serial= [HW,ALSA]
  1316. snd-sgalaxy= [HW,ALSA]
  1317. snd-sonicvibes= [HW,ALSA]
  1318. snd-sun-amd7930=
  1319. [HW,ALSA]
  1320. snd-sun-cs4231= [HW,ALSA]
  1321. snd-trident= [HW,ALSA]
  1322. snd-usb-audio= [HW,ALSA,USB]
  1323. snd-via82xx= [HW,ALSA]
  1324. snd-virmidi= [HW,ALSA]
  1325. snd-wavefront= [HW,ALSA]
  1326. snd-ymfpci= [HW,ALSA]
  1327. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1328. See Documentation/sonypi.txt
  1329. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1330. See Documentation/specialix.txt.
  1331. spia_io_base= [HW,MTD]
  1332. spia_fio_base=
  1333. spia_pedr=
  1334. spia_peddr=
  1335. sscape= [HW,OSS]
  1336. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1337. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1338. See Documentation/scsi/st.txt.
  1339. st0x= [HW,SCSI]
  1340. See header of drivers/scsi/seagate.c.
  1341. sti= [PARISC,HW]
  1342. Format: <num>
  1343. Set the STI (builtin display/keyboard on the HP-PARISC
  1344. machines) console (graphic card) which should be used
  1345. as the initial boot-console.
  1346. See also comment in drivers/video/console/sticore.c.
  1347. sti_font= [HW]
  1348. See comment in drivers/video/console/sticore.c.
  1349. stifb= [HW]
  1350. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1351. sunrpc.pool_mode=
  1352. [NFS]
  1353. Control how the NFS server code allocates CPUs to
  1354. service thread pools. Depending on how many NICs
  1355. you have and where their interrupts are bound, this
  1356. option will affect which CPUs will do NFS serving.
  1357. Note: this parameter cannot be changed while the
  1358. NFS server is running.
  1359. auto the server chooses an appropriate mode
  1360. automatically using heuristics
  1361. global a single global pool contains all CPUs
  1362. percpu one pool for each CPU
  1363. pernode one pool for each NUMA node (equivalent
  1364. to global on non-NUMA machines)
  1365. swiotlb= [IA-64] Number of I/O TLB slabs
  1366. switches= [HW,M68k]
  1367. sym53c416= [HW,SCSI]
  1368. See header of drivers/scsi/sym53c416.c.
  1369. sysrq_always_enabled
  1370. [KNL]
  1371. Ignore sysrq setting - this boot parameter will
  1372. neutralize any effect of /proc/sys/kernel/sysrq.
  1373. Useful for debugging.
  1374. t128= [HW,SCSI]
  1375. See header of drivers/scsi/t128.c.
  1376. tdfx= [HW,DRM]
  1377. thash_entries= [KNL,NET]
  1378. Set number of hash buckets for TCP connection
  1379. thermal.act= [HW,ACPI]
  1380. -1: disable all active trip points in all thermal zones
  1381. <degrees C>: override all lowest active trip points
  1382. thermal.nocrt= [HW,ACPI]
  1383. Set to disable actions on ACPI thermal zone
  1384. critical and hot trip points.
  1385. thermal.off= [HW,ACPI]
  1386. 1: disable ACPI thermal control
  1387. thermal.psv= [HW,ACPI]
  1388. -1: disable all passive trip points
  1389. <degrees C>: override all passive trip points to this value
  1390. thermal.tzp= [HW,ACPI]
  1391. Specify global default ACPI thermal zone polling rate
  1392. <deci-seconds>: poll all this frequency
  1393. 0: no polling (default)
  1394. time Show timing data prefixed to each printk message line
  1395. [deprecated, see 'printk.time']
  1396. tipar.timeout= [HW,PPT]
  1397. Set communications timeout in tenths of a second
  1398. (default 15).
  1399. tipar.delay= [HW,PPT]
  1400. Set inter-bit delay in microseconds (default 10).
  1401. tmc8xx= [HW,SCSI]
  1402. See header of drivers/scsi/seagate.c.
  1403. tmscsim= [HW,SCSI]
  1404. See comment before function dc390_setup() in
  1405. drivers/scsi/tmscsim.c.
  1406. tp720= [HW,PS2]
  1407. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1408. Format:
  1409. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1410. tsdev.xres= [TS] Horizontal screen resolution.
  1411. tsdev.yres= [TS] Vertical screen resolution.
  1412. turbografx.map[2|3]= [HW,JOY]
  1413. TurboGraFX parallel port interface
  1414. Format:
  1415. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1416. See also Documentation/input/joystick-parport.txt
  1417. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1418. See header of drivers/scsi/u14-34f.c.
  1419. uart401= [HW,OSS]
  1420. Format: <io>,<irq>
  1421. uart6850= [HW,OSS]
  1422. Format: <io>,<irq>
  1423. uhci-hcd.ignore_oc=
  1424. [USB] Ignore overcurrent events (default N).
  1425. Some badly-designed motherboards generate lots of
  1426. bogus events, for ports that aren't wired to
  1427. anything. Set this parameter to avoid log spamming.
  1428. Note that genuine overcurrent events won't be
  1429. reported either.
  1430. usbcore.autosuspend=
  1431. [USB] The autosuspend time delay (in seconds) used
  1432. for newly-detected USB devices (default 2). This
  1433. is the time required before an idle device will be
  1434. autosuspended. Devices for which the delay is set
  1435. to a negative value won't be autosuspended at all.
  1436. usbhid.mousepoll=
  1437. [USBHID] The interval which mice are to be polled at.
  1438. vdso= [X86-32,SH,x86-64]
  1439. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  1440. vdso=1: enable VDSO (default)
  1441. vdso=0: disable VDSO mapping
  1442. vector= [IA-64,SMP]
  1443. vector=percpu: enable percpu vector domain
  1444. video= [FB] Frame buffer configuration
  1445. See Documentation/fb/modedb.txt.
  1446. vga= [BOOT,X86-32] Select a particular video mode
  1447. See Documentation/i386/boot.txt and
  1448. Documentation/svga.txt.
  1449. Use vga=ask for menu.
  1450. This is actually a boot loader parameter; the value is
  1451. passed to the kernel using a special protocol.
  1452. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1453. size of <nn>. This can be used to increase the
  1454. minimum size (128MB on x86). It can also be used to
  1455. decrease the size and leave more room for directly
  1456. mapped kernel RAM.
  1457. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1458. Format: <command>
  1459. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1460. Format: <command>
  1461. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1462. Format: <command>
  1463. waveartist= [HW,OSS]
  1464. Format: <io>,<irq>,<dma>,<dma2>
  1465. wd33c93= [HW,SCSI]
  1466. See header of drivers/scsi/wd33c93.c.
  1467. wd7000= [HW,SCSI]
  1468. See header of drivers/scsi/wd7000.c.
  1469. wdt= [WDT] Watchdog
  1470. See Documentation/watchdog/wdt.txt.
  1471. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1472. xd_geo= See header of drivers/block/xd.c.
  1473. xirc2ps_cs= [NET,PCMCIA]
  1474. Format:
  1475. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1476. norandmaps Don't use address space randomization
  1477. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
  1478. unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
  1479. This is useful to get more information why
  1480. you got a "dwarf2 unwinder stuck"
  1481. ______________________________________________________________________
  1482. TODO:
  1483. Add documentation for ALSA options.
  1484. Add more DRM drivers.