kernel-parameters.txt 54 KB

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  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. ALSA ALSA sound support is enabled.
  26. APIC APIC support is enabled.
  27. APM Advanced Power Management support is enabled.
  28. AX25 Appropriate AX.25 support is enabled.
  29. CD Appropriate CD 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-32 IA-32 aka i386 architecture is enabled.
  37. IA-64 IA-64 architecture is enabled.
  38. IOSCHED More than one I/O scheduler is enabled.
  39. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  40. ISAPNP ISA PnP code is enabled.
  41. ISDN Appropriate ISDN support is enabled.
  42. JOY Appropriate joystick support is enabled.
  43. LIBATA Libata driver is enabled
  44. LP Printer support is enabled.
  45. LOOP Loopback device support is enabled.
  46. M68k M68k architecture is enabled.
  47. These options have more detailed description inside of
  48. Documentation/m68k/kernel-options.txt.
  49. MCA MCA bus support is enabled.
  50. MDA MDA console support is enabled.
  51. MOUSE Appropriate mouse support is enabled.
  52. MSI Message Signaled Interrupts (PCI).
  53. MTD MTD support is enabled.
  54. NET Appropriate network support is enabled.
  55. NUMA NUMA support is enabled.
  56. GENERIC_TIME The generic timeofday code is enabled.
  57. NFS Appropriate NFS support is enabled.
  58. OSS OSS sound support is enabled.
  59. PARIDE The ParIDE 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. X86-64 X86-64 architecture is enabled.
  87. More X86-64 boot options can be found in
  88. Documentation/x86_64/boot-options.txt .
  89. In addition, the following text indicates that the option:
  90. BUGS= Relates to possible processor bugs on the said processor.
  91. KNL Is a kernel start-up parameter.
  92. BOOT Is a boot loader parameter.
  93. Parameters denoted with BOOT are actually interpreted by the boot
  94. loader, and have no meaning to the kernel directly.
  95. Do not modify the syntax of boot loader parameters without extreme
  96. need or coordination with <Documentation/i386/boot.txt>.
  97. There are also arch-specific kernel-parameters not documented here.
  98. See for example <Documentation/x86_64/boot-options.txt>.
  99. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  100. a trailing = on the name of any parameter states that that parameter will
  101. be entered as an environment variable, whereas its absence indicates that
  102. it will appear as a kernel argument readable via /proc/cmdline by programs
  103. running once the system is up.
  104. The number of kernel parameters is not limited, but the length of the
  105. complete command line (parameters including spaces etc.) is limited to
  106. a fixed number of characters. This limit depends on the architecture
  107. and is between 256 and 4096 characters. It is defined in the file
  108. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  109. 53c7xx= [HW,SCSI] Amiga SCSI controllers
  110. See header of drivers/scsi/53c7xx.c.
  111. See also Documentation/scsi/ncr53c7xx.txt.
  112. acpi= [HW,ACPI,X86-64,i386]
  113. Advanced Configuration and Power Interface
  114. Format: { force | off | ht | strict | noirq }
  115. force -- enable ACPI if default was off
  116. off -- disable ACPI if default was on
  117. noirq -- do not use ACPI for IRQ routing
  118. ht -- run only enough ACPI to enable Hyper Threading
  119. strict -- Be less tolerant of platforms that are not
  120. strictly ACPI specification compliant.
  121. See also Documentation/pm.txt, pci=noacpi
  122. acpi_apic_instance= [ACPI, IOAPIC]
  123. Format: <int>
  124. 2: use 2nd APIC table, if available
  125. 1,0: use 1st APIC table
  126. default: 2
  127. acpi_sleep= [HW,ACPI] Sleep options
  128. Format: { s3_bios, s3_mode }
  129. See Documentation/power/video.txt
  130. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  131. Format: { level | edge | high | low }
  132. acpi_irq_balance [HW,ACPI]
  133. ACPI will balance active IRQs
  134. default in APIC mode
  135. acpi_irq_nobalance [HW,ACPI]
  136. ACPI will not move active IRQs (default)
  137. default in PIC mode
  138. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  139. use by PCI
  140. Format: <irq>,<irq>...
  141. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  142. Format: <irq>,<irq>...
  143. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  144. Format: To spoof as Windows 98: ="Microsoft Windows"
  145. acpi_osi= [HW,ACPI] empty param disables _OSI
  146. acpi_serialize [HW,ACPI] force serialization of AML methods
  147. acpi_skip_timer_override [HW,ACPI]
  148. Recognize and ignore IRQ0/pin2 Interrupt Override.
  149. For broken nForce2 BIOS resulting in XT-PIC timer.
  150. acpi_use_timer_override [HW,ACPI}
  151. Use timer override. For some broken Nvidia NF5 boards
  152. that require a timer override, but don't have
  153. HPET
  154. acpi_dbg_layer= [HW,ACPI]
  155. Format: <int>
  156. Each bit of the <int> indicates an ACPI debug layer,
  157. 1: enable, 0: disable. It is useful for boot time
  158. debugging. After system has booted up, it can be set
  159. via /proc/acpi/debug_layer.
  160. acpi_dbg_level= [HW,ACPI]
  161. Format: <int>
  162. Each bit of the <int> indicates an ACPI debug level,
  163. 1: enable, 0: disable. It is useful for boot time
  164. debugging. After system has booted up, it can be set
  165. via /proc/acpi/debug_level.
  166. acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
  167. acpi_generic_hotkey [HW,ACPI]
  168. Allow consolidated generic hotkey driver to
  169. override platform specific driver.
  170. See also Documentation/acpi-hotkey.txt.
  171. acpi_pm_good [IA-32,X86-64]
  172. Override the pmtimer bug detection: force the kernel
  173. to assume that this machine's pmtimer latches its value
  174. and always returns good values.
  175. enable_timer_pin_1 [i386,x86-64]
  176. Enable PIN 1 of APIC timer
  177. Can be useful to work around chipset bugs
  178. (in particular on some ATI chipsets).
  179. The kernel tries to set a reasonable default.
  180. disable_timer_pin_1 [i386,x86-64]
  181. Disable PIN 1 of APIC timer
  182. Can be useful to work around chipset bugs.
  183. ad1816= [HW,OSS]
  184. Format: <io>,<irq>,<dma>,<dma2>
  185. See also Documentation/sound/oss/AD1816.
  186. ad1848= [HW,OSS]
  187. Format: <io>,<irq>,<dma>,<dma2>,<type>
  188. adlib= [HW,OSS]
  189. Format: <io>
  190. advansys= [HW,SCSI]
  191. See header of drivers/scsi/advansys.c.
  192. advwdt= [HW,WDT] Advantech WDT
  193. Format: <iostart>,<iostop>
  194. aedsp16= [HW,OSS] Audio Excel DSP 16
  195. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  196. See also header of sound/oss/aedsp16.c.
  197. aha152x= [HW,SCSI]
  198. See Documentation/scsi/aha152x.txt.
  199. aha1542= [HW,SCSI]
  200. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  201. aic7xxx= [HW,SCSI]
  202. See Documentation/scsi/aic7xxx.txt.
  203. aic79xx= [HW,SCSI]
  204. See Documentation/scsi/aic79xx.txt.
  205. amijoy.map= [HW,JOY] Amiga joystick support
  206. Map of devices attached to JOY0DAT and JOY1DAT
  207. Format: <a>,<b>
  208. See also Documentation/kernel/input/joystick.txt
  209. analog.map= [HW,JOY] Analog joystick and gamepad support
  210. Specifies type or capabilities of an analog joystick
  211. connected to one of 16 gameports
  212. Format: <type1>,<type2>,..<type16>
  213. apc= [HW,SPARC]
  214. Power management functions (SPARCstation-4/5 + deriv.)
  215. Format: noidle
  216. Disable APC CPU standby support. SPARCstation-Fox does
  217. not play well with APC CPU idle - disable it if you have
  218. APC and your system crashes randomly.
  219. apic= [APIC,i386] Change the output verbosity whilst booting
  220. Format: { quiet (default) | verbose | debug }
  221. Change the amount of debugging information output
  222. when initialising the APIC and IO-APIC components.
  223. apm= [APM] Advanced Power Management
  224. See header of arch/i386/kernel/apm.c.
  225. applicom= [HW]
  226. Format: <mem>,<irq>
  227. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  228. Format: <io>,<irq>,<nodeID>
  229. ataflop= [HW,M68k]
  230. atarimouse= [HW,MOUSE] Atari Mouse
  231. atascsi= [HW,SCSI] Atari SCSI
  232. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  233. EzKey and similar keyboards
  234. atkbd.reset= [HW] Reset keyboard during initialization
  235. atkbd.set= [HW] Select keyboard code set
  236. Format: <int> (2 = AT (default), 3 = PS/2)
  237. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  238. keyboards
  239. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  240. Format: <bool> (0 = real, 1 = synthetic (default))
  241. atkbd.softrepeat= [HW]
  242. Use software keyboard repeat
  243. autotest [IA64]
  244. aztcd= [HW,CD] Aztech CD268 CDROM driver
  245. Format: <io>,0x79 (?)
  246. baycom_epp= [HW,AX25]
  247. Format: <io>,<mode>
  248. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  249. Format: <io>,<mode>
  250. See header of drivers/net/hamradio/baycom_par.c.
  251. baycom_ser_fdx= [HW,AX25]
  252. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  253. Format: <io>,<irq>,<mode>[,<baud>]
  254. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  255. baycom_ser_hdx= [HW,AX25]
  256. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  257. Format: <io>,<irq>,<mode>
  258. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  259. blkmtd_device= [HW,MTD]
  260. blkmtd_erasesz=
  261. blkmtd_ro=
  262. blkmtd_bs=
  263. blkmtd_count=
  264. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  265. bttv.radio= Most important insmod options are available as
  266. kernel args too.
  267. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  268. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  269. BusLogic= [HW,SCSI]
  270. See drivers/scsi/BusLogic.c, comment before function
  271. BusLogic_ParseDriverOptions().
  272. c101= [NET] Moxa C101 synchronous serial card
  273. cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
  274. Sometimes CPU hardware bugs make them report the cache
  275. size incorrectly. The kernel will attempt work arounds
  276. to fix known problems, but for some CPUs it is not
  277. possible to determine what the correct size should be.
  278. This option provides an override for these situations.
  279. cdu31a= [HW,CD]
  280. Format: <io>,<irq>[,PAS]
  281. See header of drivers/cdrom/cdu31a.c.
  282. chandev= [HW,NET] Generic channel device initialisation
  283. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  284. Format: { "0" | "1" }
  285. See security/selinux/Kconfig help text.
  286. 0 -- check protection applied by kernel (includes
  287. any implied execute protection).
  288. 1 -- check protection requested by application.
  289. Default value is set via a kernel config option.
  290. Value can be changed at runtime via
  291. /selinux/checkreqprot.
  292. clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
  293. [Deprecated]
  294. Forces specified clocksource (if available) to be used
  295. when calculating gettimeofday(). If specified
  296. clocksource is not available, it defaults to PIT.
  297. Format: { pit | tsc | cyclone | pmtmr }
  298. code_bytes [IA32] How many bytes of object code to print in an
  299. oops report.
  300. Range: 0 - 8192
  301. Default: 64
  302. disable_8254_timer
  303. enable_8254_timer
  304. [IA32/X86_64] Disable/Enable interrupt 0 timer routing
  305. over the 8254 in addition to over the IO-APIC. The
  306. kernel tries to set a sensible default.
  307. hpet= [IA-32,HPET] option to disable HPET and use PIT.
  308. Format: disable
  309. cm206= [HW,CD]
  310. Format: { auto | [<io>,][<irq>] }
  311. com20020= [HW,NET] ARCnet - COM20020 chipset
  312. Format:
  313. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  314. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  315. Format: <io>[,<irq>]
  316. com90xx= [HW,NET]
  317. ARCnet - COM90xx chipset (memory-mapped buffers)
  318. Format: <io>[,<irq>[,<memstart>]]
  319. condev= [HW,S390] console device
  320. conmode=
  321. console= [KNL] Output console device and options.
  322. tty<n> Use the virtual console device <n>.
  323. ttyS<n>[,options]
  324. ttyUSB0[,options]
  325. Use the specified serial port. The options are of
  326. the form "bbbbpnf", where "bbbb" is the baud rate,
  327. "p" is parity ("n", "o", or "e"), "n" is number of
  328. bits, and "f" is flow control ("r" for RTS or
  329. omit it). Default is "9600n8".
  330. See Documentation/serial-console.txt for more
  331. information. See
  332. Documentation/networking/netconsole.txt for an
  333. alternative.
  334. uart,io,<addr>[,options]
  335. uart,mmio,<addr>[,options]
  336. Start an early, polled-mode console on the 8250/16550
  337. UART at the specified I/O port or MMIO address,
  338. switching to the matching ttyS device later. The
  339. options are the same as for ttyS, above.
  340. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  341. Format:
  342. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  343. cpia_pp= [HW,PPT]
  344. Format: { parport<nr> | auto | none }
  345. crashkernel=nn[KMG]@ss[KMG]
  346. [KNL] Reserve a chunk of physical memory to
  347. hold a kernel to switch to with kexec on panic.
  348. cs4232= [HW,OSS]
  349. Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
  350. cs89x0_dma= [HW,NET]
  351. Format: <dma>
  352. cs89x0_media= [HW,NET]
  353. Format: { rj45 | aui | bnc }
  354. cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
  355. dasd= [HW,NET]
  356. See header of drivers/s390/block/dasd_devmap.c.
  357. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  358. (one device per port)
  359. Format: <port#>,<type>
  360. See also Documentation/input/joystick-parport.txt
  361. debug [KNL] Enable kernel debugging (events log level).
  362. debug_locks_verbose=
  363. [KNL] verbose self-tests
  364. Format=<0|1>
  365. Print debugging info while doing the locking API
  366. self-tests.
  367. We default to 0 (no extra messages), setting it to
  368. 1 will print _a lot_ more information - normally
  369. only useful to kernel developers.
  370. decnet= [HW,NET]
  371. Format: <area>[,<node>]
  372. See also Documentation/networking/decnet.txt.
  373. dhash_entries= [KNL]
  374. Set number of hash buckets for dentry cache.
  375. digi= [HW,SERIAL]
  376. IO parameters + enable/disable command.
  377. digiepca= [HW,SERIAL]
  378. See drivers/char/README.epca and
  379. Documentation/digiepca.txt.
  380. dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
  381. support available.
  382. Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
  383. dmasound= [HW,OSS] Sound subsystem buffers
  384. dscc4.setup= [NET]
  385. dtc3181e= [HW,SCSI]
  386. earlyprintk= [IA-32,X86-64,SH]
  387. earlyprintk=vga
  388. earlyprintk=serial[,ttySn[,baudrate]]
  389. Append ",keep" to not disable it when the real console
  390. takes over.
  391. Only vga or serial at a time, not both.
  392. Currently only ttyS0 and ttyS1 are supported.
  393. Interaction with the standard serial driver is not
  394. very good.
  395. The VGA output is eventually overwritten by the real
  396. console.
  397. eata= [HW,SCSI]
  398. ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
  399. Format: <int>
  400. 0: polling mode
  401. non-0: interrupt mode (default)
  402. eda= [HW,PS2]
  403. edb= [HW,PS2]
  404. edd= [EDD]
  405. Format: {"of[f]" | "sk[ipmbr]"}
  406. See comment in arch/i386/boot/edd.S
  407. eicon= [HW,ISDN]
  408. Format: <id>,<membase>,<irq>
  409. eisa_irq_edge= [PARISC,HW]
  410. See header of drivers/parisc/eisa.c.
  411. elanfreq= [IA-32]
  412. See comment before function elanfreq_setup() in
  413. arch/i386/kernel/cpu/cpufreq/elanfreq.c.
  414. elevator= [IOSCHED]
  415. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  416. See Documentation/block/as-iosched.txt and
  417. Documentation/block/deadline-iosched.txt for details.
  418. elfcorehdr= [IA-32, X86_64]
  419. Specifies physical address of start of kernel core
  420. image elf header. Generally kexec loader will
  421. pass this option to capture kernel.
  422. See Documentation/kdump/kdump.txt for details.
  423. enforcing [SELINUX] Set initial enforcing status.
  424. Format: {"0" | "1"}
  425. See security/selinux/Kconfig help text.
  426. 0 -- permissive (log only, no denials).
  427. 1 -- enforcing (deny and log).
  428. Default value is 0.
  429. Value can be changed at runtime via /selinux/enforce.
  430. es1371= [HW,OSS]
  431. Format: <spdif>,[<nomix>,[<amplifier>]]
  432. See also header of sound/oss/es1371.c.
  433. ether= [HW,NET] Ethernet cards parameters
  434. This option is obsoleted by the "netdev=" option, which
  435. has equivalent usage. See its documentation for details.
  436. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  437. Format: <io>[,<irq>]
  438. failslab=
  439. fail_page_alloc=
  440. fail_make_request=[KNL]
  441. General fault injection mechanism.
  442. Format: <interval>,<probability>,<space>,<times>
  443. See also /Documentation/fault-injection/.
  444. fd_mcs= [HW,SCSI]
  445. See header of drivers/scsi/fd_mcs.c.
  446. fdomain= [HW,SCSI]
  447. See header of drivers/scsi/fdomain.c.
  448. floppy= [HW]
  449. See Documentation/floppy.txt.
  450. gamecon.map[2|3]=
  451. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  452. support via parallel port (up to 5 devices per port)
  453. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  454. See also Documentation/input/joystick-parport.txt
  455. gamma= [HW,DRM]
  456. gdth= [HW,SCSI]
  457. See header of drivers/scsi/gdth.c.
  458. gpt [EFI] Forces disk with valid GPT signature but
  459. invalid Protective MBR to be treated as GPT.
  460. gscd= [HW,CD]
  461. Format: <io>
  462. gvp11= [HW,SCSI]
  463. hashdist= [KNL,NUMA] Large hashes allocated during boot
  464. are distributed across NUMA nodes. Defaults on
  465. for IA-64, off otherwise.
  466. Format: 0 | 1 (for off | on)
  467. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  468. hd= [EIDE] (E)IDE hard drive subsystem geometry
  469. Format: <cyl>,<head>,<sect>
  470. hd?= [HW] (E)IDE subsystem
  471. hd?lun= See Documentation/ide.txt.
  472. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  473. size of <nn>. This works even on boxes that have no
  474. highmem otherwise. This also works to reduce highmem
  475. size on bigger boxes.
  476. highres= [KNL] Enable/disable high resolution timer mode.
  477. Valid parameters: "on", "off"
  478. Default: "on"
  479. hisax= [HW,ISDN]
  480. See Documentation/isdn/README.HiSax.
  481. hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
  482. i8042.direct [HW] Put keyboard port into non-translated mode
  483. i8042.dumbkbd [HW] Pretend that controller can only read data from
  484. keyboard and cannot control its state
  485. (Don't attempt to blink the leds)
  486. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  487. i8042.nokbd [HW] Don't check/create keyboard port
  488. i8042.nomux [HW] Don't check presence of an active multiplexing
  489. controller
  490. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  491. controllers
  492. i8042.panicblink=
  493. [HW] Frequency with which keyboard LEDs should blink
  494. when kernel panics (default is 0.5 sec)
  495. i8042.reset [HW] Reset the controller during init and cleanup
  496. i8042.unlock [HW] Unlock (ignore) the keylock
  497. i810= [HW,DRM]
  498. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  499. indicates that the driver is running on unsupported
  500. hardware.
  501. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  502. does not match list of supported models.
  503. i8k.power_status
  504. [HW] Report power status in /proc/i8k
  505. (disabled by default)
  506. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  507. capability is set.
  508. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  509. See Documentation/mca.txt.
  510. icn= [HW,ISDN]
  511. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  512. ide= [HW] (E)IDE subsystem
  513. Format: ide=nodma or ide=doubler or ide=reverse
  514. See Documentation/ide.txt.
  515. ide?= [HW] (E)IDE subsystem
  516. Format: ide?=noprobe or chipset specific parameters.
  517. See Documentation/ide.txt.
  518. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  519. See Documentation/ide.txt.
  520. idle= [HW]
  521. Format: idle=poll or idle=halt
  522. ignore_loglevel [KNL]
  523. Ignore loglevel setting - this will print /all/
  524. kernel messages to the console. Useful for debugging.
  525. ihash_entries= [KNL]
  526. Set number of hash buckets for inode cache.
  527. in2000= [HW,SCSI]
  528. See header of drivers/scsi/in2000.c.
  529. init= [KNL]
  530. Format: <full_path>
  531. Run specified binary instead of /sbin/init as init
  532. process.
  533. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  534. for working out where the kernel is dying during
  535. startup.
  536. initrd= [BOOT] Specify the location of the initial ramdisk
  537. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  538. Format: <irq>
  539. combined_mode= [HW] control which driver uses IDE ports in combined
  540. mode: legacy IDE driver, libata, or both
  541. (in the libata case, libata.atapi_enabled=1 may be
  542. useful as well). Note that using the ide or libata
  543. options may affect your device naming (e.g. by
  544. changing hdc to sdb).
  545. Format: combined (default), ide, or libata
  546. inttest= [IA64]
  547. io7= [HW] IO7 for Marvel based alpha systems
  548. See comment before marvel_specify_io7 in
  549. arch/alpha/kernel/core_marvel.c.
  550. ip= [IP_PNP]
  551. See Documentation/nfsroot.txt.
  552. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  553. See comment before ip2_setup() in drivers/char/ip2.c.
  554. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  555. See header of drivers/scsi/ips.c.
  556. ports= [IP_VS_FTP] IPVS ftp helper module
  557. Default is 21.
  558. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  559. may be specified.
  560. Format: <port>,<port>....
  561. irqfixup [HW]
  562. When an interrupt is not handled search all handlers
  563. for it. Intended to get systems with badly broken
  564. firmware running.
  565. irqpoll [HW]
  566. When an interrupt is not handled search all handlers
  567. for it. Also check all handlers each timer
  568. interrupt. Intended to get systems with badly broken
  569. firmware running.
  570. isapnp= [ISAPNP]
  571. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  572. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  573. Format:
  574. <cpu number>,...,<cpu number>
  575. or
  576. <cpu number>-<cpu number> (must be a positive range in ascending order)
  577. or a mixture
  578. <cpu number>,...,<cpu number>-<cpu number>
  579. This option can be used to specify one or more CPUs
  580. to isolate from the general SMP balancing and scheduling
  581. algorithms. The only way to move a process onto or off
  582. an "isolated" CPU is via the CPU affinity syscalls.
  583. <cpu number> begins at 0 and the maximum value is
  584. "number of CPUs in system - 1".
  585. This option is the preferred way to isolate CPUs. The
  586. alternative -- manually setting the CPU mask of all
  587. tasks in the system -- can cause problems and
  588. suboptimal load balancer performance.
  589. isp16= [HW,CD]
  590. Format: <io>,<irq>,<dma>,<setup>
  591. iucv= [HW,NET]
  592. js= [HW,JOY] Analog joystick
  593. See Documentation/input/joystick.txt.
  594. keepinitrd [HW,ARM]
  595. kstack=N [IA-32,X86-64] Print N words from the kernel stack
  596. in oops dumps.
  597. l2cr= [PPC]
  598. lapic [IA-32,APIC] Enable the local APIC even if BIOS
  599. disabled it.
  600. lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
  601. Format: addr:<io>,irq:<irq>
  602. llsc*= [IA64] See function print_params() in
  603. arch/ia64/sn/kernel/llsc4.c.
  604. load_ramdisk= [RAM] List of ramdisks to load from floppy
  605. See Documentation/ramdisk.txt.
  606. lockd.nlm_grace_period=P [NFS] Assign grace period.
  607. Format: <integer>
  608. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  609. Format: <integer>
  610. lockd.nlm_timeout=T [NFS] Assign timeout value.
  611. Format: <integer>
  612. lockd.nlm_udpport=M [NFS] Assign UDP port.
  613. Format: <integer>
  614. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  615. Format: <irq>
  616. loglevel= All Kernel Messages with a loglevel smaller than the
  617. console loglevel will be printed to the console. It can
  618. also be changed with klogd or other programs. The
  619. loglevels are defined as follows:
  620. 0 (KERN_EMERG) system is unusable
  621. 1 (KERN_ALERT) action must be taken immediately
  622. 2 (KERN_CRIT) critical conditions
  623. 3 (KERN_ERR) error conditions
  624. 4 (KERN_WARNING) warning conditions
  625. 5 (KERN_NOTICE) normal but significant condition
  626. 6 (KERN_INFO) informational
  627. 7 (KERN_DEBUG) debug-level messages
  628. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  629. Format: { n | nk | nM }
  630. n must be a power of two. The default size
  631. is set in the kernel config file.
  632. lp=0 [LP] Specify parallel ports to use, e.g,
  633. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  634. lp=reset first parallel port). 'lp=0' disables the
  635. lp=auto printer driver. 'lp=reset' (which can be
  636. specified in addition to the ports) causes
  637. attached printers to be reset. Using
  638. lp=port1,port2,... specifies the parallel ports
  639. to associate lp devices with, starting with
  640. lp0. A port specification may be 'none' to skip
  641. that lp device, or a parport name such as
  642. 'parport0'. Specifying 'lp=auto' instead of a
  643. port specification list means that device IDs
  644. from each port should be examined, to see if
  645. an IEEE 1284-compliant printer is attached; if
  646. so, the driver will manage that printer.
  647. See also header of drivers/char/lp.c.
  648. lpj=n [KNL]
  649. Sets loops_per_jiffy to given constant, thus avoiding
  650. time-consuming boot-time autodetection (up to 250 ms per
  651. CPU). 0 enables autodetection (default). To determine
  652. the correct value for your kernel, boot with normal
  653. autodetection and see what value is printed. Note that
  654. on SMP systems the preset will be applied to all CPUs,
  655. which is likely to cause problems if your CPUs need
  656. significantly divergent settings. An incorrect value
  657. will cause delays in the kernel to be wrong, leading to
  658. unpredictable I/O errors and other breakage. Although
  659. unlikely, in the extreme case this might damage your
  660. hardware.
  661. ltpc= [NET]
  662. Format: <io>,<irq>,<dma>
  663. mac5380= [HW,SCSI] Format:
  664. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  665. mac53c9x= [HW,SCSI] Format:
  666. <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  667. machvec= [IA64] Force the use of a particular machine-vector
  668. (machvec) in a generic kernel.
  669. Example: machvec=hpzx1_swiotlb
  670. max_loop= [LOOP] Maximum number of loopback devices that can
  671. be mounted
  672. Format: <1-256>
  673. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  674. should make use of.
  675. Using "nosmp" or "maxcpus=0" will disable SMP
  676. entirely (the MPS table probe still happens, though).
  677. A command-line option of "maxcpus=<NUM>", where <NUM>
  678. is an integer greater than 0, limits the maximum number
  679. of CPUs activated in SMP mode to <NUM>.
  680. Using "maxcpus=1" on an SMP kernel is the trivial
  681. case of an SMP kernel with only one CPU.
  682. max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
  683. equal to this physical address is ignored.
  684. max_luns= [SCSI] Maximum number of LUNs to probe.
  685. Should be between 1 and 2^32-1.
  686. max_report_luns=
  687. [SCSI] Maximum number of LUNs received.
  688. Should be between 1 and 16384.
  689. mca-pentium [BUGS=IA-32]
  690. mcatest= [IA-64]
  691. mcd= [HW,CD]
  692. Format: <port>,<irq>,<mitsumi_bug_93_wait>
  693. mcdx= [HW,CD]
  694. mce [IA-32] Machine Check Exception
  695. md= [HW] RAID subsystems devices and level
  696. See Documentation/md.txt.
  697. mdacon= [MDA]
  698. Format: <first>,<last>
  699. Specifies range of consoles to be captured by the MDA.
  700. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  701. Amount of memory to be used when the kernel is not able
  702. to see the whole system memory or for test.
  703. [IA-32] Use together with memmap= to avoid physical
  704. address space collisions. Without memmap= PCI devices
  705. could be placed at addresses belonging to unused RAM.
  706. mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
  707. memory.
  708. memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
  709. E820 memory map, as specified by the user.
  710. Such memmap=exactmap lines can be constructed based on
  711. BIOS output or other requirements. See the memmap=nn@ss
  712. option description.
  713. memmap=nn[KMG]@ss[KMG]
  714. [KNL] Force usage of a specific region of memory
  715. Region of memory to be used, from ss to ss+nn.
  716. memmap=nn[KMG]#ss[KMG]
  717. [KNL,ACPI] Mark specific memory as ACPI data.
  718. Region of memory to be used, from ss to ss+nn.
  719. memmap=nn[KMG]$ss[KMG]
  720. [KNL,ACPI] Mark specific memory as reserved.
  721. Region of memory to be used, from ss to ss+nn.
  722. meye.*= [HW] Set MotionEye Camera parameters
  723. See Documentation/video4linux/meye.txt.
  724. mga= [HW,DRM]
  725. migration_cost=
  726. [KNL,SMP] debug: override scheduler migration costs
  727. Format: <level-1-usecs>,<level-2-usecs>,...
  728. This debugging option can be used to override the
  729. default scheduler migration cost matrix. The numbers
  730. are indexed by 'CPU domain distance'.
  731. E.g. migration_cost=1000,2000,3000 on an SMT NUMA
  732. box will set up an intra-core migration cost of
  733. 1 msec, an inter-core migration cost of 2 msecs,
  734. and an inter-node migration cost of 3 msecs.
  735. WARNING: using the wrong values here can break
  736. scheduler performance, so it's only for scheduler
  737. development purposes, not production environments.
  738. migration_debug=
  739. [KNL,SMP] migration cost auto-detect verbosity
  740. Format=<0|1|2>
  741. If a system's migration matrix reported at bootup
  742. seems erroneous then this option can be used to
  743. increase verbosity of the detection process.
  744. We default to 0 (no extra messages), 1 will print
  745. some more information, and 2 will be really
  746. verbose (probably only useful if you also have a
  747. serial console attached to the system).
  748. migration_factor=
  749. [KNL,SMP] multiply/divide migration costs by a factor
  750. Format=<percent>
  751. This debug option can be used to proportionally
  752. increase or decrease the auto-detected migration
  753. costs for all entries of the migration matrix.
  754. E.g. migration_factor=150 will increase migration
  755. costs by 50%. (and thus the scheduler will be less
  756. eager migrating cache-hot tasks)
  757. migration_factor=80 will decrease migration costs
  758. by 20%. (thus the scheduler will be more eager to
  759. migrate tasks)
  760. WARNING: using the wrong values here can break
  761. scheduler performance, so it's only for scheduler
  762. development purposes, not production environments.
  763. mousedev.tap_time=
  764. [MOUSE] Maximum time between finger touching and
  765. leaving touchpad surface for touch to be considered
  766. a tap and be reported as a left button click (for
  767. touchpads working in absolute mode only).
  768. Format: <msecs>
  769. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  770. reporting absolute coordinates, such as tablets
  771. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  772. reporting absolute coordinates, such as tablets
  773. mpu401= [HW,OSS]
  774. Format: <io>,<irq>
  775. MTD_Partition= [MTD]
  776. Format: <name>,<region-number>,<size>,<offset>
  777. MTD_Region= [MTD] Format:
  778. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  779. mtdparts= [MTD]
  780. See drivers/mtd/cmdline.c.
  781. mtouchusb.raw_coordinates=
  782. [HW] Make the MicroTouch USB driver use raw coordinates
  783. ('y', default) or cooked coordinates ('n')
  784. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  785. NCR_D700= [HW,SCSI]
  786. See header of drivers/scsi/NCR_D700.c.
  787. ncr5380= [HW,SCSI]
  788. ncr53c400= [HW,SCSI]
  789. ncr53c400a= [HW,SCSI]
  790. ncr53c406a= [HW,SCSI]
  791. ncr53c8xx= [HW,SCSI]
  792. netdev= [NET] Network devices parameters
  793. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  794. Note that mem_start is often overloaded to mean
  795. something different and driver-specific.
  796. This usage is only documented in each driver source
  797. file if at all.
  798. nfsaddrs= [NFS]
  799. See Documentation/nfsroot.txt.
  800. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  801. See Documentation/nfsroot.txt.
  802. nfs.callback_tcpport=
  803. [NFS] set the TCP port on which the NFSv4 callback
  804. channel should listen.
  805. nfs.idmap_cache_timeout=
  806. [NFS] set the maximum lifetime for idmapper cache
  807. entries.
  808. nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
  809. no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
  810. emulation library even if a 387 maths coprocessor
  811. is present.
  812. noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  813. when set.
  814. Format: <int>
  815. noaliencache [MM, NUMA] Disables the allcoation of alien caches in
  816. the slab allocator. Saves per-node memory, but will
  817. impact performance on real NUMA hardware.
  818. noalign [KNL,ARM]
  819. noapic [SMP,APIC] Tells the kernel to not make use of any
  820. IOAPICs that may be present in the system.
  821. noasync [HW,M68K] Disables async and sync negotiation for
  822. all devices.
  823. nobats [PPC] Do not use BATs for mapping kernel lowmem
  824. on "Classic" PPC cores.
  825. nocache [ARM]
  826. nodelayacct [KNL] Disable per-task delay accounting
  827. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  828. noexec [IA-64]
  829. noexec [IA-32,X86-64]
  830. noexec=on: enable non-executable mappings (default)
  831. noexec=off: disable nn-executable mappings
  832. nofxsr [BUGS=IA-32] Disables x86 floating point extended
  833. register save and restore. The kernel will only save
  834. legacy floating-point registers on task switch.
  835. nohlt [BUGS=ARM]
  836. no-hlt [BUGS=IA-32] Tells the kernel that the hlt
  837. instruction doesn't work correctly and not to
  838. use it.
  839. nohalt [IA-64] Tells the kernel not to use the power saving
  840. function PAL_HALT_LIGHT when idle. This increases
  841. power-consumption. On the positive side, it reduces
  842. interrupt wake-up latency, which may improve performance
  843. in certain environments such as networked servers or
  844. real-time systems.
  845. nohz= [KNL] Boottime enable/disable dynamic ticks
  846. Valid arguments: on, off
  847. Default: on
  848. noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
  849. noirqdebug [IA-32] Disables the code which attempts to detect and
  850. disable unhandled interrupt sources.
  851. no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
  852. broken timer IRQ sources.
  853. noisapnp [ISAPNP] Disables ISA PnP code.
  854. noinitrd [RAM] Tells the kernel not to load any configured
  855. initial RAM disk.
  856. nointroute [IA-64]
  857. nolapic [IA-32,APIC] Do not enable or use the local APIC.
  858. noltlbs [PPC] Do not use large page/tlb entries for kernel
  859. lowmem mapping on PPC40x.
  860. nomca [IA-64] Disable machine check abort handling
  861. nomce [IA-32] Machine Check Exception
  862. noresidual [PPC] Don't use residual data on PReP machines.
  863. noresume [SWSUSP] Disables resume and restores original swap
  864. space.
  865. no-scroll [VGA] Disables scrollback.
  866. This is required for the Braillex ib80-piezo Braille
  867. reader made by F.H. Papenmeier (Germany).
  868. nosbagart [IA-64]
  869. nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
  870. nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
  871. nosync [HW,M68K] Disables sync negotiation for all devices.
  872. notsc [BUGS=IA-32] Disable Time Stamp Counter
  873. nousb [USB] Disable the USB subsystem
  874. nowb [ARM]
  875. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  876. opl3= [HW,OSS]
  877. Format: <io>
  878. opl3sa2= [HW,OSS] Format:
  879. <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
  880. oprofile.timer= [HW]
  881. Use timer interrupt instead of performance counters
  882. optcd= [HW,CD]
  883. Format: <io>
  884. osst= [HW,SCSI] SCSI Tape Driver
  885. Format: <buffer_size>,<write_threshold>
  886. See also Documentation/scsi/st.txt.
  887. panic= [KNL] Kernel behaviour on panic
  888. Format: <timeout>
  889. parkbd.port= [HW] Parallel port number the keyboard adapter is
  890. connected to, default is 0.
  891. Format: <parport#>
  892. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  893. 0 for XT, 1 for AT (default is AT).
  894. Format: <mode>
  895. parport= [HW,PPT] Specify parallel ports. 0 disables.
  896. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  897. Use 'auto' to force the driver to use any
  898. IRQ/DMA settings detected (the default is to
  899. ignore detected IRQ/DMA settings because of
  900. possible conflicts). You can specify the base
  901. address, IRQ, and DMA settings; IRQ and DMA
  902. should be numbers, or 'auto' (for using detected
  903. settings on that particular port), or 'nofifo'
  904. (to avoid using a FIFO even if it is detected).
  905. Parallel ports are assigned in the order they
  906. are specified on the command line, starting
  907. with parport0.
  908. parport_init_mode= [HW,PPT]
  909. Configure VIA parallel port to operate in
  910. a specific mode. This is necessary on Pegasos
  911. computer where firmware has no options for setting
  912. up parallel port mode and sets it to spp.
  913. Currently this function knows 686a and 8231 chips.
  914. Format: [spp|ps2|epp|ecp|ecpepp]
  915. pas2= [HW,OSS] Format:
  916. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  917. pas16= [HW,SCSI]
  918. See header of drivers/scsi/pas16.c.
  919. pause_on_oops=
  920. Halt all CPUs after the first oops has been printed for
  921. the specified number of seconds. This is to be used if
  922. your oopses keep scrolling off the screen.
  923. pcbit= [HW,ISDN]
  924. pcd. [PARIDE]
  925. See header of drivers/block/paride/pcd.c.
  926. See also Documentation/paride.txt.
  927. pci=option[,option...] [PCI] various PCI subsystem options:
  928. off [IA-32] don't probe for the PCI bus
  929. bios [IA-32] force use of PCI BIOS, don't access
  930. the hardware directly. Use this if your machine
  931. has a non-standard PCI host bridge.
  932. nobios [IA-32] disallow use of PCI BIOS, only direct
  933. hardware access methods are allowed. Use this
  934. if you experience crashes upon bootup and you
  935. suspect they are caused by the BIOS.
  936. conf1 [IA-32] Force use of PCI Configuration
  937. Mechanism 1.
  938. conf2 [IA-32] Force use of PCI Configuration
  939. Mechanism 2.
  940. nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
  941. Configuration
  942. nomsi [MSI] If the PCI_MSI kernel config parameter is
  943. enabled, this kernel boot option can be used to
  944. disable the use of MSI interrupts system-wide.
  945. nosort [IA-32] Don't sort PCI devices according to
  946. order given by the PCI BIOS. This sorting is
  947. done to get a device order compatible with
  948. older kernels.
  949. biosirq [IA-32] Use PCI BIOS calls to get the interrupt
  950. routing table. These calls are known to be buggy
  951. on several machines and they hang the machine
  952. when used, but on other computers it's the only
  953. way to get the interrupt routing table. Try
  954. this option if the kernel is unable to allocate
  955. IRQs or discover secondary PCI buses on your
  956. motherboard.
  957. rom [IA-32] Assign address space to expansion ROMs.
  958. Use with caution as certain devices share
  959. address decoders between ROMs and other
  960. resources.
  961. irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
  962. assigned automatically to PCI devices. You can
  963. make the kernel exclude IRQs of your ISA cards
  964. this way.
  965. pirqaddr=0xAAAAA [IA-32] Specify the physical address
  966. of the PIRQ table (normally generated
  967. by the BIOS) if it is outside the
  968. F0000h-100000h range.
  969. lastbus=N [IA-32] Scan all buses thru bus #N. Can be
  970. useful if the kernel is unable to find your
  971. secondary buses and you want to tell it
  972. explicitly which ones they are.
  973. assign-busses [IA-32] Always assign all PCI bus
  974. numbers ourselves, overriding
  975. whatever the firmware may have done.
  976. usepirqmask [IA-32] Honor the possible IRQ mask stored
  977. in the BIOS $PIR table. This is needed on
  978. some systems with broken BIOSes, notably
  979. some HP Pavilion N5400 and Omnibook XE3
  980. notebooks. This will have no effect if ACPI
  981. IRQ routing is enabled.
  982. noacpi [IA-32] Do not use ACPI for IRQ routing
  983. or for PCI scanning.
  984. routeirq Do IRQ routing for all PCI devices.
  985. This is normally done in pci_enable_device(),
  986. so this option is a temporary workaround
  987. for broken drivers that don't call it.
  988. firmware [ARM] Do not re-enumerate the bus but instead
  989. just use the configuration from the
  990. bootloader. This is currently used on
  991. IXP2000 systems where the bus has to be
  992. configured a certain way for adjunct CPUs.
  993. noearly [X86] Don't do any early type 1 scanning.
  994. This might help on some broken boards which
  995. machine check when some devices' config space
  996. is read. But various workarounds are disabled
  997. and some IOMMU drivers will not work.
  998. bfsort Sort PCI devices into breadth-first order.
  999. This sorting is done to get a device
  1000. order compatible with older (<= 2.4) kernels.
  1001. nobfsort Don't sort PCI devices into breadth-first order.
  1002. cbiosize=nn[KMG] The fixed amount of bus space which is
  1003. reserved for the CardBus bridge's IO window.
  1004. The default value is 256 bytes.
  1005. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1006. reserved for the CardBus bridge's memory
  1007. window. The default value is 64 megabytes.
  1008. pcmv= [HW,PCMCIA] BadgePAD 4
  1009. pd. [PARIDE]
  1010. See Documentation/paride.txt.
  1011. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1012. boot time.
  1013. Format: { 0 | 1 }
  1014. See arch/parisc/kernel/pdc_chassis.c
  1015. pf. [PARIDE]
  1016. See Documentation/paride.txt.
  1017. pg. [PARIDE]
  1018. See Documentation/paride.txt.
  1019. pirq= [SMP,APIC] Manual mp-table setup
  1020. See Documentation/i386/IO-APIC.txt.
  1021. plip= [PPT,NET] Parallel port network link
  1022. Format: { parport<nr> | timid | 0 }
  1023. See also Documentation/parport.txt.
  1024. pnpacpi= [ACPI]
  1025. { off }
  1026. pnpbios= [ISAPNP]
  1027. { on | off | curr | res | no-curr | no-res }
  1028. pnp_reserve_irq=
  1029. [ISAPNP] Exclude IRQs for the autoconfiguration
  1030. pnp_reserve_dma=
  1031. [ISAPNP] Exclude DMAs for the autoconfiguration
  1032. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1033. Ranges are in pairs (I/O port base and size).
  1034. pnp_reserve_mem=
  1035. [ISAPNP] Exclude memory regions for the
  1036. autoconfiguration.
  1037. Ranges are in pairs (memory base and size).
  1038. profile= [KNL] Enable kernel profiling via /proc/profile
  1039. Format: [schedule,]<number>
  1040. Param: "schedule" - profile schedule points.
  1041. Param: <number> - step/bucket size as a power of 2 for
  1042. statistical time based profiling.
  1043. Param: "sleep" - profile D-state sleeping (millisecs)
  1044. processor.max_cstate= [HW,ACPI]
  1045. Limit processor to maximum C-state
  1046. max_cstate=9 overrides any DMI blacklist limit.
  1047. processor.nocst [HW,ACPI]
  1048. Ignore the _CST method to determine C-states,
  1049. instead using the legacy FADT method
  1050. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1051. before loading.
  1052. See Documentation/ramdisk.txt.
  1053. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1054. probe for; one of (bare|imps|exps|lifebook|any).
  1055. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1056. per second.
  1057. psmouse.resetafter= [HW,MOUSE]
  1058. Try to reset the device after so many bad packets
  1059. (0 = never).
  1060. psmouse.resolution=
  1061. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1062. psmouse.smartscroll=
  1063. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1064. 0 = disabled, 1 = enabled (default).
  1065. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1066. Format:
  1067. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1068. pt. [PARIDE]
  1069. See Documentation/paride.txt.
  1070. quiet [KNL] Disable most log messages
  1071. r128= [HW,DRM]
  1072. raid= [HW,RAID]
  1073. See Documentation/md.txt.
  1074. ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
  1075. See Documentation/ramdisk.txt.
  1076. ramdisk_blocksize= [RAM]
  1077. See Documentation/ramdisk.txt.
  1078. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1079. New name for the ramdisk parameter.
  1080. See Documentation/ramdisk.txt.
  1081. rcu.blimit= [KNL,BOOT] Set maximum number of finished
  1082. RCU callbacks to process in one batch.
  1083. rcu.qhimark= [KNL,BOOT] Set threshold of queued
  1084. RCU callbacks over which batch limiting is disabled.
  1085. rcu.qlowmark= [KNL,BOOT] Set threshold of queued
  1086. RCU callbacks below which batch limiting is re-enabled.
  1087. rdinit= [KNL]
  1088. Format: <full_path>
  1089. Run specified binary instead of /init from the ramdisk,
  1090. used for early userspace startup. See initrd.
  1091. reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1092. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1093. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1094. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1095. reservetop= [IA-32]
  1096. Format: nn[KMG]
  1097. Reserves a hole at the top of the kernel virtual
  1098. address space.
  1099. reset_devices [KNL] Force drivers to reset the underlying device
  1100. during initialization.
  1101. resume= [SWSUSP]
  1102. Specify the partition device for software suspend
  1103. resume_offset= [SWSUSP]
  1104. Specify the offset from the beginning of the partition
  1105. given by "resume=" at which the swap header is located,
  1106. in <PAGE_SIZE> units (needed only for swap files).
  1107. See Documentation/power/swsusp-and-swap-files.txt
  1108. retain_initrd [RAM] Keep initrd memory after extraction
  1109. rhash_entries= [KNL,NET]
  1110. Set number of hash buckets for route cache
  1111. riscom8= [HW,SERIAL]
  1112. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1113. ro [KNL] Mount root device read-only on boot
  1114. root= [KNL] Root filesystem
  1115. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1116. mount the root filesystem
  1117. rootflags= [KNL] Set root filesystem mount option string
  1118. rootfstype= [KNL] Set root filesystem type
  1119. rw [KNL] Mount root device read-write on boot
  1120. S [KNL] Run init in single mode
  1121. sa1100ir [NET]
  1122. See drivers/net/irda/sa1100_ir.c.
  1123. sb= [HW,OSS]
  1124. Format: <io>,<irq>,<dma>,<dma2>
  1125. sbni= [NET] Granch SBNI12 leased line adapter
  1126. sbpcd= [HW,CD] Soundblaster CD adapter
  1127. Format: <io>,<type>
  1128. See a comment before function sbpcd_setup() in
  1129. drivers/cdrom/sbpcd.c.
  1130. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1131. Format: <io>[,<timeout>[,<isapnp>]]
  1132. scsi_debug_*= [SCSI]
  1133. See drivers/scsi/scsi_debug.c.
  1134. scsi_default_dev_flags=
  1135. [SCSI] SCSI default device flags
  1136. Format: <integer>
  1137. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1138. Format: <vendor>:<model>:<flags>
  1139. (flags are integer value)
  1140. scsi_logging= [SCSI]
  1141. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1142. discovered. async scans them in kernel threads,
  1143. allowing boot to proceed. none ignores them, expecting
  1144. user space to do the scan.
  1145. selinux [SELINUX] Disable or enable SELinux at boot time.
  1146. Format: { "0" | "1" }
  1147. See security/selinux/Kconfig help text.
  1148. 0 -- disable.
  1149. 1 -- enable.
  1150. Default value is set via kernel config option.
  1151. If enabled at boot time, /selinux/disable can be used
  1152. later to disable prior to initial policy load.
  1153. selinux_compat_net =
  1154. [SELINUX] Set initial selinux_compat_net flag value.
  1155. Format: { "0" | "1" }
  1156. 0 -- use new secmark-based packet controls
  1157. 1 -- use legacy packet controls
  1158. Default value is 0 (preferred).
  1159. Value can be changed at runtime via
  1160. /selinux/compat_net.
  1161. serialnumber [BUGS=IA-32]
  1162. sg_def_reserved_size= [SCSI]
  1163. shapers= [NET]
  1164. Maximal number of shapers.
  1165. sim710= [SCSI,HW]
  1166. See header of drivers/scsi/sim710.c.
  1167. simeth= [IA-64]
  1168. simscsi=
  1169. sjcd= [HW,CD]
  1170. Format: <io>,<irq>,<dma>
  1171. See header of drivers/cdrom/sjcd.c.
  1172. slram= [HW,MTD]
  1173. smart2= [HW]
  1174. Format: <io1>[,<io2>[,...,<io8>]]
  1175. snd-ad1816a= [HW,ALSA]
  1176. snd-ad1848= [HW,ALSA]
  1177. snd-ali5451= [HW,ALSA]
  1178. snd-als100= [HW,ALSA]
  1179. snd-als4000= [HW,ALSA]
  1180. snd-azt2320= [HW,ALSA]
  1181. snd-cmi8330= [HW,ALSA]
  1182. snd-cmipci= [HW,ALSA]
  1183. snd-cs4231= [HW,ALSA]
  1184. snd-cs4232= [HW,ALSA]
  1185. snd-cs4236= [HW,ALSA]
  1186. snd-cs4281= [HW,ALSA]
  1187. snd-cs46xx= [HW,ALSA]
  1188. snd-dt019x= [HW,ALSA]
  1189. snd-dummy= [HW,ALSA]
  1190. snd-emu10k1= [HW,ALSA]
  1191. snd-ens1370= [HW,ALSA]
  1192. snd-ens1371= [HW,ALSA]
  1193. snd-es968= [HW,ALSA]
  1194. snd-es1688= [HW,ALSA]
  1195. snd-es18xx= [HW,ALSA]
  1196. snd-es1938= [HW,ALSA]
  1197. snd-es1968= [HW,ALSA]
  1198. snd-fm801= [HW,ALSA]
  1199. snd-gusclassic= [HW,ALSA]
  1200. snd-gusextreme= [HW,ALSA]
  1201. snd-gusmax= [HW,ALSA]
  1202. snd-hdsp= [HW,ALSA]
  1203. snd-ice1712= [HW,ALSA]
  1204. snd-intel8x0= [HW,ALSA]
  1205. snd-interwave= [HW,ALSA]
  1206. snd-interwave-stb=
  1207. [HW,ALSA]
  1208. snd-korg1212= [HW,ALSA]
  1209. snd-maestro3= [HW,ALSA]
  1210. snd-mpu401= [HW,ALSA]
  1211. snd-mtpav= [HW,ALSA]
  1212. snd-nm256= [HW,ALSA]
  1213. snd-opl3sa2= [HW,ALSA]
  1214. snd-opti92x-ad1848=
  1215. [HW,ALSA]
  1216. snd-opti92x-cs4231=
  1217. [HW,ALSA]
  1218. snd-opti93x= [HW,ALSA]
  1219. snd-pmac= [HW,ALSA]
  1220. snd-rme32= [HW,ALSA]
  1221. snd-rme96= [HW,ALSA]
  1222. snd-rme9652= [HW,ALSA]
  1223. snd-sb8= [HW,ALSA]
  1224. snd-sb16= [HW,ALSA]
  1225. snd-sbawe= [HW,ALSA]
  1226. snd-serial= [HW,ALSA]
  1227. snd-sgalaxy= [HW,ALSA]
  1228. snd-sonicvibes= [HW,ALSA]
  1229. snd-sun-amd7930=
  1230. [HW,ALSA]
  1231. snd-sun-cs4231= [HW,ALSA]
  1232. snd-trident= [HW,ALSA]
  1233. snd-usb-audio= [HW,ALSA,USB]
  1234. snd-via82xx= [HW,ALSA]
  1235. snd-virmidi= [HW,ALSA]
  1236. snd-wavefront= [HW,ALSA]
  1237. snd-ymfpci= [HW,ALSA]
  1238. sonycd535= [HW,CD]
  1239. Format: <io>[,<irq>]
  1240. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1241. See Documentation/sonypi.txt
  1242. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1243. See Documentation/specialix.txt.
  1244. spia_io_base= [HW,MTD]
  1245. spia_fio_base=
  1246. spia_pedr=
  1247. spia_peddr=
  1248. sscape= [HW,OSS]
  1249. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1250. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1251. See Documentation/scsi/st.txt.
  1252. st0x= [HW,SCSI]
  1253. See header of drivers/scsi/seagate.c.
  1254. sti= [PARISC,HW]
  1255. Format: <num>
  1256. Set the STI (builtin display/keyboard on the HP-PARISC
  1257. machines) console (graphic card) which should be used
  1258. as the initial boot-console.
  1259. See also comment in drivers/video/console/sticore.c.
  1260. sti_font= [HW]
  1261. See comment in drivers/video/console/sticore.c.
  1262. stifb= [HW]
  1263. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1264. sunrpc.pool_mode=
  1265. [NFS]
  1266. Control how the NFS server code allocates CPUs to
  1267. service thread pools. Depending on how many NICs
  1268. you have and where their interrupts are bound, this
  1269. option will affect which CPUs will do NFS serving.
  1270. Note: this parameter cannot be changed while the
  1271. NFS server is running.
  1272. auto the server chooses an appropriate mode
  1273. automatically using heuristics
  1274. global a single global pool contains all CPUs
  1275. percpu one pool for each CPU
  1276. pernode one pool for each NUMA node (equivalent
  1277. to global on non-NUMA machines)
  1278. swiotlb= [IA-64] Number of I/O TLB slabs
  1279. switches= [HW,M68k]
  1280. sym53c416= [HW,SCSI]
  1281. See header of drivers/scsi/sym53c416.c.
  1282. sysrq_always_enabled
  1283. [KNL]
  1284. Ignore sysrq setting - this boot parameter will
  1285. neutralize any effect of /proc/sys/kernel/sysrq.
  1286. Useful for debugging.
  1287. t128= [HW,SCSI]
  1288. See header of drivers/scsi/t128.c.
  1289. tdfx= [HW,DRM]
  1290. thash_entries= [KNL,NET]
  1291. Set number of hash buckets for TCP connection
  1292. time Show timing data prefixed to each printk message line
  1293. clocksource= [GENERIC_TIME] Override the default clocksource
  1294. Override the default clocksource and use the clocksource
  1295. with the name specified.
  1296. tipar.timeout= [HW,PPT]
  1297. Set communications timeout in tenths of a second
  1298. (default 15).
  1299. tipar.delay= [HW,PPT]
  1300. Set inter-bit delay in microseconds (default 10).
  1301. tmc8xx= [HW,SCSI]
  1302. See header of drivers/scsi/seagate.c.
  1303. tmscsim= [HW,SCSI]
  1304. See comment before function dc390_setup() in
  1305. drivers/scsi/tmscsim.c.
  1306. tp720= [HW,PS2]
  1307. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1308. Format:
  1309. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1310. tsdev.xres= [TS] Horizontal screen resolution.
  1311. tsdev.yres= [TS] Vertical screen resolution.
  1312. turbografx.map[2|3]= [HW,JOY]
  1313. TurboGraFX parallel port interface
  1314. Format:
  1315. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1316. See also Documentation/input/joystick-parport.txt
  1317. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1318. See header of drivers/scsi/u14-34f.c.
  1319. uart401= [HW,OSS]
  1320. Format: <io>,<irq>
  1321. uart6850= [HW,OSS]
  1322. Format: <io>,<irq>
  1323. uhci-hcd.ignore_oc=
  1324. [USB] Ignore overcurrent events (default N).
  1325. Some badly-designed motherboards generate lots of
  1326. bogus events, for ports that aren't wired to
  1327. anything. Set this parameter to avoid log spamming.
  1328. Note that genuine overcurrent events won't be
  1329. reported either.
  1330. usbcore.autosuspend=
  1331. [USB] The autosuspend time delay (in seconds) used
  1332. for newly-detected USB devices (default 2). This
  1333. is the time required before an idle device will be
  1334. autosuspended. Devices for which the delay is set
  1335. to 0 won't be autosuspended at all.
  1336. usbhid.mousepoll=
  1337. [USBHID] The interval which mice are to be polled at.
  1338. vdso= [IA-32,SH]
  1339. vdso=1: enable VDSO (default)
  1340. vdso=0: disable VDSO mapping
  1341. video= [FB] Frame buffer configuration
  1342. See Documentation/fb/modedb.txt.
  1343. vga= [BOOT,IA-32] Select a particular video mode
  1344. See Documentation/i386/boot.txt and
  1345. Documentation/svga.txt.
  1346. Use vga=ask for menu.
  1347. This is actually a boot loader parameter; the value is
  1348. passed to the kernel using a special protocol.
  1349. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1350. size of <nn>. This can be used to increase the
  1351. minimum size (128MB on x86). It can also be used to
  1352. decrease the size and leave more room for directly
  1353. mapped kernel RAM.
  1354. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1355. Format: <command>
  1356. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1357. Format: <command>
  1358. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1359. Format: <command>
  1360. waveartist= [HW,OSS]
  1361. Format: <io>,<irq>,<dma>,<dma2>
  1362. wd33c93= [HW,SCSI]
  1363. See header of drivers/scsi/wd33c93.c.
  1364. wd7000= [HW,SCSI]
  1365. See header of drivers/scsi/wd7000.c.
  1366. wdt= [WDT] Watchdog
  1367. See Documentation/watchdog/watchdog.txt.
  1368. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1369. xd_geo= See header of drivers/block/xd.c.
  1370. xirc2ps_cs= [NET,PCMCIA]
  1371. Format:
  1372. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1373. norandmaps Don't use address space randomization
  1374. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
  1375. unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
  1376. This is useful to get more information why
  1377. you got a "dwarf2 unwinder stuck"
  1378. ______________________________________________________________________
  1379. TODO:
  1380. Add documentation for ALSA options.
  1381. Add more DRM drivers.