kernel-parameters.txt 65 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. AGP AGP (Accelerated Graphics Port) is enabled.
  26. ALSA ALSA sound support is enabled.
  27. APIC APIC support is enabled.
  28. APM Advanced Power Management support is enabled.
  29. AVR32 AVR32 architecture is enabled.
  30. AX25 Appropriate AX.25 support is enabled.
  31. BLACKFIN Blackfin architecture is enabled.
  32. DRM Direct Rendering Management support is enabled.
  33. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
  34. EFI EFI Partitioning (GPT) is enabled
  35. EIDE EIDE/ATAPI support is enabled.
  36. FB The frame buffer device is enabled.
  37. HW Appropriate hardware is enabled.
  38. IA-64 IA-64 architecture is enabled.
  39. IOSCHED More than one I/O scheduler is enabled.
  40. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  41. ISAPNP ISA PnP code is enabled.
  42. ISDN Appropriate ISDN support is enabled.
  43. JOY Appropriate joystick support is enabled.
  44. LIBATA Libata driver is enabled
  45. LP Printer support is enabled.
  46. LOOP Loopback device support is enabled.
  47. M68k M68k architecture is enabled.
  48. These options have more detailed description inside of
  49. Documentation/m68k/kernel-options.txt.
  50. MCA MCA bus support is enabled.
  51. MDA MDA console support is enabled.
  52. MOUSE Appropriate mouse support is enabled.
  53. MSI Message Signaled Interrupts (PCI).
  54. MTD MTD (Memory Technology Device) support is enabled.
  55. NET Appropriate network support is enabled.
  56. NUMA NUMA support is enabled.
  57. GENERIC_TIME The generic timeofday code is enabled.
  58. NFS Appropriate NFS support is enabled.
  59. OSS OSS sound support is enabled.
  60. PV_OPS A paravirtualized kernel is enabled.
  61. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  62. PARISC The PA-RISC architecture is enabled.
  63. PCI PCI bus support is enabled.
  64. PCIE PCI Express support is enabled.
  65. PCMCIA The PCMCIA subsystem is enabled.
  66. PNP Plug & Play support is enabled.
  67. PPC PowerPC architecture is enabled.
  68. PPT Parallel port support is enabled.
  69. PS2 Appropriate PS/2 support is enabled.
  70. RAM RAM disk support is enabled.
  71. ROOTPLUG The example Root Plug LSM is enabled.
  72. S390 S390 architecture is enabled.
  73. SCSI Appropriate SCSI support is enabled.
  74. A lot of drivers has their options described inside of
  75. Documentation/scsi/.
  76. SECURITY Different security models are enabled.
  77. SELINUX SELinux support is enabled.
  78. SERIAL Serial support is enabled.
  79. SH SuperH architecture is enabled.
  80. SMP The kernel is an SMP kernel.
  81. SPARC Sparc architecture is enabled.
  82. SWSUSP Software suspend is enabled.
  83. TS Appropriate touchscreen support is enabled.
  84. USB USB support is enabled.
  85. USBHID USB Human Interface Device support is enabled.
  86. V4L Video For Linux support is enabled.
  87. VGA The VGA console has been enabled.
  88. VT Virtual terminal support is enabled.
  89. WDT Watchdog support is enabled.
  90. XT IBM PC/XT MFM hard disk support is enabled.
  91. X86-32 X86-32, aka i386 architecture is enabled.
  92. X86-64 X86-64 architecture is enabled.
  93. More X86-64 boot options can be found in
  94. Documentation/x86_64/boot-options.txt .
  95. In addition, the following text indicates that the option:
  96. BUGS= Relates to possible processor bugs on the said processor.
  97. KNL Is a kernel start-up parameter.
  98. BOOT Is a boot loader parameter.
  99. Parameters denoted with BOOT are actually interpreted by the boot
  100. loader, and have no meaning to the kernel directly.
  101. Do not modify the syntax of boot loader parameters without extreme
  102. need or coordination with <Documentation/i386/boot.txt>.
  103. There are also arch-specific kernel-parameters not documented here.
  104. See for example <Documentation/x86_64/boot-options.txt>.
  105. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  106. a trailing = on the name of any parameter states that that parameter will
  107. be entered as an environment variable, whereas its absence indicates that
  108. it will appear as a kernel argument readable via /proc/cmdline by programs
  109. running once the system is up.
  110. The number of kernel parameters is not limited, but the length of the
  111. complete command line (parameters including spaces etc.) is limited to
  112. a fixed number of characters. This limit depends on the architecture
  113. and is between 256 and 4096 characters. It is defined in the file
  114. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  115. acpi= [HW,ACPI,X86-64,i386]
  116. Advanced Configuration and Power Interface
  117. Format: { force | off | ht | strict | noirq }
  118. force -- enable ACPI if default was off
  119. off -- disable ACPI if default was on
  120. noirq -- do not use ACPI for IRQ routing
  121. ht -- run only enough ACPI to enable Hyper Threading
  122. strict -- Be less tolerant of platforms that are not
  123. strictly ACPI specification compliant.
  124. See also Documentation/pm.txt, pci=noacpi
  125. acpi_apic_instance= [ACPI, IOAPIC]
  126. Format: <int>
  127. 2: use 2nd APIC table, if available
  128. 1,0: use 1st APIC table
  129. default: 0
  130. acpi_sleep= [HW,ACPI] Sleep options
  131. Format: { s3_bios, s3_mode, s3_beep }
  132. See Documentation/power/video.txt for s3_bios and s3_mode.
  133. s3_beep is for debugging; it makes the PC's speaker beep
  134. as soon as the kernel's real-mode entry point is called.
  135. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  136. Format: { level | edge | high | low }
  137. acpi_irq_balance [HW,ACPI]
  138. ACPI will balance active IRQs
  139. default in APIC mode
  140. acpi_irq_nobalance [HW,ACPI]
  141. ACPI will not move active IRQs (default)
  142. default in PIC mode
  143. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  144. use by PCI
  145. Format: <irq>,<irq>...
  146. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  147. Format: <irq>,<irq>...
  148. acpi_new_pts_ordering [HW,ACPI]
  149. Enforce the ACPI 2.0 ordering of the _PTS control
  150. method wrt putting devices into low power states
  151. default: pre ACPI 2.0 ordering of _PTS
  152. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  153. acpi_no_initrd_override [KNL,ACPI]
  154. Disable loading custom ACPI tables from the initramfs
  155. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  156. Format: To spoof as Windows 98: ="Microsoft Windows"
  157. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  158. acpi_osi="string1" # add string1 -- only one string
  159. acpi_osi="!string2" # remove built-in string2
  160. acpi_osi= # disable all strings
  161. acpi_serialize [HW,ACPI] force serialization of AML methods
  162. acpi_skip_timer_override [HW,ACPI]
  163. Recognize and ignore IRQ0/pin2 Interrupt Override.
  164. For broken nForce2 BIOS resulting in XT-PIC timer.
  165. acpi_use_timer_override [HW,ACPI}
  166. Use timer override. For some broken Nvidia NF5 boards
  167. that require a timer override, but don't have
  168. HPET
  169. acpi.debug_layer= [HW,ACPI]
  170. Format: <int>
  171. Each bit of the <int> indicates an ACPI debug layer,
  172. 1: enable, 0: disable. It is useful for boot time
  173. debugging. After system has booted up, it can be set
  174. via /sys/module/acpi/parameters/debug_layer.
  175. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  176. Available bits (add the numbers together) to enable debug output
  177. for specific parts of the ACPI subsystem:
  178. 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
  179. 0x10 namespace 0x20 parser 0x40 dispatcher
  180. 0x80 executer 0x100 resources 0x200 acpica debugger
  181. 0x400 os services 0x800 acpica disassembler.
  182. The number can be in decimal or prefixed with 0x in hex.
  183. Warning: Many of these options can produce a lot of
  184. output and make your system unusable. Be very careful.
  185. acpi.debug_level= [HW,ACPI]
  186. Format: <int>
  187. Each bit of the <int> indicates an ACPI debug level,
  188. 1: enable, 0: disable. It is useful for boot time
  189. debugging. After system has booted up, it can be set
  190. via /sys/module/acpi/parameters/debug_level.
  191. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  192. Available bits (add the numbers together) to enable different
  193. debug output levels of the ACPI subsystem:
  194. 0x01 error 0x02 warn 0x04 init 0x08 debug object
  195. 0x10 info 0x20 init names 0x40 parse 0x80 load
  196. 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
  197. 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
  198. 0x10000 resources 0x20000 user requests 0x40000 package.
  199. The number can be in decimal or prefixed with 0x in hex.
  200. Warning: Many of these options can produce a lot of
  201. output and make your system unusable. Be very careful.
  202. acpi_pm_good [X86-32,X86-64]
  203. Override the pmtimer bug detection: force the kernel
  204. to assume that this machine's pmtimer latches its value
  205. and always returns good values.
  206. agp= [AGP]
  207. { off | try_unsupported }
  208. off: disable AGP support
  209. try_unsupported: try to drive unsupported chipsets
  210. (may crash computer or cause data corruption)
  211. enable_timer_pin_1 [i386,x86-64]
  212. Enable PIN 1 of APIC timer
  213. Can be useful to work around chipset bugs
  214. (in particular on some ATI chipsets).
  215. The kernel tries to set a reasonable default.
  216. disable_timer_pin_1 [i386,x86-64]
  217. Disable PIN 1 of APIC timer
  218. Can be useful to work around chipset bugs.
  219. ad1848= [HW,OSS]
  220. Format: <io>,<irq>,<dma>,<dma2>,<type>
  221. advansys= [HW,SCSI]
  222. See header of drivers/scsi/advansys.c.
  223. advwdt= [HW,WDT] Advantech WDT
  224. Format: <iostart>,<iostop>
  225. aedsp16= [HW,OSS] Audio Excel DSP 16
  226. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  227. See also header of sound/oss/aedsp16.c.
  228. aha152x= [HW,SCSI]
  229. See Documentation/scsi/aha152x.txt.
  230. aha1542= [HW,SCSI]
  231. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  232. aic7xxx= [HW,SCSI]
  233. See Documentation/scsi/aic7xxx.txt.
  234. aic79xx= [HW,SCSI]
  235. See Documentation/scsi/aic79xx.txt.
  236. amijoy.map= [HW,JOY] Amiga joystick support
  237. Map of devices attached to JOY0DAT and JOY1DAT
  238. Format: <a>,<b>
  239. See also Documentation/kernel/input/joystick.txt
  240. analog.map= [HW,JOY] Analog joystick and gamepad support
  241. Specifies type or capabilities of an analog joystick
  242. connected to one of 16 gameports
  243. Format: <type1>,<type2>,..<type16>
  244. apc= [HW,SPARC]
  245. Power management functions (SPARCstation-4/5 + deriv.)
  246. Format: noidle
  247. Disable APC CPU standby support. SPARCstation-Fox does
  248. not play well with APC CPU idle - disable it if you have
  249. APC and your system crashes randomly.
  250. apic= [APIC,i386] Advanced Programmable Interrupt Controller
  251. Change the output verbosity whilst booting
  252. Format: { quiet (default) | verbose | debug }
  253. Change the amount of debugging information output
  254. when initialising the APIC and IO-APIC components.
  255. apm= [APM] Advanced Power Management
  256. See header of arch/i386/kernel/apm.c.
  257. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  258. Format: <io>,<irq>,<nodeID>
  259. ataflop= [HW,M68k]
  260. atarimouse= [HW,MOUSE] Atari Mouse
  261. atascsi= [HW,SCSI] Atari SCSI
  262. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  263. EzKey and similar keyboards
  264. atkbd.reset= [HW] Reset keyboard during initialization
  265. atkbd.set= [HW] Select keyboard code set
  266. Format: <int> (2 = AT (default), 3 = PS/2)
  267. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  268. keyboards
  269. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  270. Format: <bool> (0 = real, 1 = synthetic (default))
  271. atkbd.softrepeat= [HW]
  272. Use software keyboard repeat
  273. autotest [IA64]
  274. baycom_epp= [HW,AX25]
  275. Format: <io>,<mode>
  276. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  277. Format: <io>,<mode>
  278. See header of drivers/net/hamradio/baycom_par.c.
  279. baycom_ser_fdx= [HW,AX25]
  280. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  281. Format: <io>,<irq>,<mode>[,<baud>]
  282. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  283. baycom_ser_hdx= [HW,AX25]
  284. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  285. Format: <io>,<irq>,<mode>
  286. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  287. boot_delay= Milliseconds to delay each printk during boot.
  288. Values larger than 10 seconds (10000) are changed to
  289. no delay (0).
  290. Format: integer
  291. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  292. bttv.radio= Most important insmod options are available as
  293. kernel args too.
  294. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  295. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  296. BusLogic= [HW,SCSI]
  297. See drivers/scsi/BusLogic.c, comment before function
  298. BusLogic_ParseDriverOptions().
  299. c101= [NET] Moxa C101 synchronous serial card
  300. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  301. Sometimes CPU hardware bugs make them report the cache
  302. size incorrectly. The kernel will attempt work arounds
  303. to fix known problems, but for some CPUs it is not
  304. possible to determine what the correct size should be.
  305. This option provides an override for these situations.
  306. capability.disable=
  307. [SECURITY] Disable capabilities. This would normally
  308. be used only if an alternative security model is to be
  309. configured. Potentially dangerous and should only be
  310. used if you are entirely sure of the consequences.
  311. ccw_timeout_log [S390]
  312. See Documentation/s390/CommonIO for details.
  313. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  314. Format: { "0" | "1" }
  315. See security/selinux/Kconfig help text.
  316. 0 -- check protection applied by kernel (includes
  317. any implied execute protection).
  318. 1 -- check protection requested by application.
  319. Default value is set via a kernel config option.
  320. Value can be changed at runtime via
  321. /selinux/checkreqprot.
  322. cio_ignore= [S390]
  323. See Documentation/s390/CommonIO for details.
  324. cio_msg= [S390]
  325. See Documentation/s390/CommonIO for details.
  326. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  327. [Deprecated]
  328. Forces specified clocksource (if available) to be used
  329. when calculating gettimeofday(). If specified
  330. clocksource is not available, it defaults to PIT.
  331. Format: { pit | tsc | cyclone | pmtmr }
  332. clocksource= [GENERIC_TIME] Override the default clocksource
  333. Format: <string>
  334. Override the default clocksource and use the clocksource
  335. with the name specified.
  336. Some clocksource names to choose from, depending on
  337. the platform:
  338. [all] jiffies (this is the base, fallback clocksource)
  339. [ACPI] acpi_pm
  340. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  341. pxa_timer,timer3,32k_counter,timer0_1
  342. [AVR32] avr32
  343. [X86-32] pit,hpet,tsc,vmi-timer;
  344. scx200_hrt on Geode; cyclone on IBM x440
  345. [MIPS] MIPS
  346. [PARISC] cr16
  347. [S390] tod
  348. [SH] SuperH
  349. [SPARC64] tick
  350. [X86-64] hpet,tsc
  351. clearcpuid=BITNUM [X86]
  352. Disable CPUID feature X for the kernel. See
  353. include/asm-x86/cpufeature.h for the valid bit numbers.
  354. Note the Linux specific bits are not necessarily
  355. stable over kernel options, but the vendor specific
  356. ones should be.
  357. Also note that user programs calling CPUID directly
  358. or using the feature without checking anything
  359. will still see it. This just prevents it from
  360. being used by the kernel or shown in /proc/cpuinfo.
  361. Also note the kernel might malfunction if you disable
  362. some critical bits.
  363. code_bytes [IA32/X86_64] How many bytes of object code to print
  364. in an oops report.
  365. Range: 0 - 8192
  366. Default: 64
  367. disable_8254_timer
  368. enable_8254_timer
  369. [IA32/X86_64] Disable/Enable interrupt 0 timer routing
  370. over the 8254 in addition to over the IO-APIC. The
  371. kernel tries to set a sensible default.
  372. hpet= [X86-32,HPET] option to control HPET usage
  373. Format: { enable (default) | disable | force }
  374. disable: disable HPET and use PIT instead
  375. force: allow force enabled of undocumented chips (ICH4,
  376. VIA, nVidia)
  377. com20020= [HW,NET] ARCnet - COM20020 chipset
  378. Format:
  379. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  380. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  381. Format: <io>[,<irq>]
  382. com90xx= [HW,NET]
  383. ARCnet - COM90xx chipset (memory-mapped buffers)
  384. Format: <io>[,<irq>[,<memstart>]]
  385. condev= [HW,S390] console device
  386. conmode=
  387. console= [KNL] Output console device and options.
  388. tty<n> Use the virtual console device <n>.
  389. ttyS<n>[,options]
  390. ttyUSB0[,options]
  391. Use the specified serial port. The options are of
  392. the form "bbbbpnf", where "bbbb" is the baud rate,
  393. "p" is parity ("n", "o", or "e"), "n" is number of
  394. bits, and "f" is flow control ("r" for RTS or
  395. omit it). Default is "9600n8".
  396. See Documentation/serial-console.txt for more
  397. information. See
  398. Documentation/networking/netconsole.txt for an
  399. alternative.
  400. uart[8250],io,<addr>[,options]
  401. uart[8250],mmio,<addr>[,options]
  402. Start an early, polled-mode console on the 8250/16550
  403. UART at the specified I/O port or MMIO address,
  404. switching to the matching ttyS device later. The
  405. options are the same as for ttyS, above.
  406. earlycon= [KNL] Output early console device and options.
  407. uart[8250],io,<addr>[,options]
  408. uart[8250],mmio,<addr>[,options]
  409. Start an early, polled-mode console on the 8250/16550
  410. UART at the specified I/O port or MMIO address.
  411. The options are the same as for ttyS, above.
  412. no_console_suspend
  413. [HW] Never suspend the console
  414. Disable suspending of consoles during suspend and
  415. hibernate operations. Once disabled, debugging
  416. messages can reach various consoles while the rest
  417. of the system is being put to sleep (ie, while
  418. debugging driver suspend/resume hooks). This may
  419. not work reliably with all consoles, but is known
  420. to work with serial and VGA consoles.
  421. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  422. Format:
  423. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  424. crashkernel=nn[KMG]@ss[KMG]
  425. [KNL] Reserve a chunk of physical memory to
  426. hold a kernel to switch to with kexec on panic.
  427. crashkernel=range1:size1[,range2:size2,...][@offset]
  428. [KNL] Same as above, but depends on the memory
  429. in the running system. The syntax of range is
  430. start-[end] where start and end are both
  431. a memory unit (amount[KMG]). See also
  432. Documentation/kdump/kdump.txt for a example.
  433. cs4232= [HW,OSS]
  434. Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
  435. cs89x0_dma= [HW,NET]
  436. Format: <dma>
  437. cs89x0_media= [HW,NET]
  438. Format: { rj45 | aui | bnc }
  439. dasd= [HW,NET]
  440. See header of drivers/s390/block/dasd_devmap.c.
  441. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  442. (one device per port)
  443. Format: <port#>,<type>
  444. See also Documentation/input/joystick-parport.txt
  445. debug [KNL] Enable kernel debugging (events log level).
  446. debug_locks_verbose=
  447. [KNL] verbose self-tests
  448. Format=<0|1>
  449. Print debugging info while doing the locking API
  450. self-tests.
  451. We default to 0 (no extra messages), setting it to
  452. 1 will print _a lot_ more information - normally
  453. only useful to kernel developers.
  454. decnet.addr= [HW,NET]
  455. Format: <area>[,<node>]
  456. See also Documentation/networking/decnet.txt.
  457. vt.default_blu= [VT]
  458. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  459. Change the default blue palette of the console.
  460. This is a 16-member array composed of values
  461. ranging from 0-255.
  462. vt.default_grn= [VT]
  463. Format: <green0>,<green1>,<green2>,...,<green15>
  464. Change the default green palette of the console.
  465. This is a 16-member array composed of values
  466. ranging from 0-255.
  467. vt.default_red= [VT]
  468. Format: <red0>,<red1>,<red2>,...,<red15>
  469. Change the default red palette of the console.
  470. This is a 16-member array composed of values
  471. ranging from 0-255.
  472. vt.default_utf8=
  473. [VT]
  474. Format=<0|1>
  475. Set system-wide default UTF-8 mode for all tty's.
  476. Default is 1, i.e. UTF-8 mode is enabled for all
  477. newly opened terminals.
  478. dhash_entries= [KNL]
  479. Set number of hash buckets for dentry cache.
  480. digi= [HW,SERIAL]
  481. IO parameters + enable/disable command.
  482. digiepca= [HW,SERIAL]
  483. See drivers/char/README.epca and
  484. Documentation/digiepca.txt.
  485. disable_mtrr_trim [X86, Intel and AMD only]
  486. By default the kernel will trim any uncacheable
  487. memory out of your available memory pool based on
  488. MTRR settings. This parameter disables that behavior,
  489. possibly causing your machine to run very slowly.
  490. dmasound= [HW,OSS] Sound subsystem buffers
  491. dscc4.setup= [NET]
  492. dtc3181e= [HW,SCSI]
  493. earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
  494. earlyprintk=vga
  495. earlyprintk=serial[,ttySn[,baudrate]]
  496. Append ",keep" to not disable it when the real console
  497. takes over.
  498. Only vga or serial at a time, not both.
  499. Currently only ttyS0 and ttyS1 are supported.
  500. Interaction with the standard serial driver is not
  501. very good.
  502. The VGA output is eventually overwritten by the real
  503. console.
  504. eata= [HW,SCSI]
  505. edd= [EDD]
  506. Format: {"of[f]" | "sk[ipmbr]"}
  507. See comment in arch/i386/boot/edd.S
  508. eisa_irq_edge= [PARISC,HW]
  509. See header of drivers/parisc/eisa.c.
  510. elanfreq= [X86-32]
  511. See comment before function elanfreq_setup() in
  512. arch/i386/kernel/cpu/cpufreq/elanfreq.c.
  513. elevator= [IOSCHED]
  514. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  515. See Documentation/block/as-iosched.txt and
  516. Documentation/block/deadline-iosched.txt for details.
  517. elfcorehdr= [X86-32, X86_64]
  518. Specifies physical address of start of kernel core
  519. image elf header. Generally kexec loader will
  520. pass this option to capture kernel.
  521. See Documentation/kdump/kdump.txt for details.
  522. enforcing [SELINUX] Set initial enforcing status.
  523. Format: {"0" | "1"}
  524. See security/selinux/Kconfig help text.
  525. 0 -- permissive (log only, no denials).
  526. 1 -- enforcing (deny and log).
  527. Default value is 0.
  528. Value can be changed at runtime via /selinux/enforce.
  529. es1371= [HW,OSS]
  530. Format: <spdif>,[<nomix>,[<amplifier>]]
  531. See also header of sound/oss/es1371.c.
  532. ether= [HW,NET] Ethernet cards parameters
  533. This option is obsoleted by the "netdev=" option, which
  534. has equivalent usage. See its documentation for details.
  535. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  536. Format: <io>[,<irq>]
  537. failslab=
  538. fail_page_alloc=
  539. fail_make_request=[KNL]
  540. General fault injection mechanism.
  541. Format: <interval>,<probability>,<space>,<times>
  542. See also /Documentation/fault-injection/.
  543. fd_mcs= [HW,SCSI]
  544. See header of drivers/scsi/fd_mcs.c.
  545. fdomain= [HW,SCSI]
  546. See header of drivers/scsi/fdomain.c.
  547. floppy= [HW]
  548. See Documentation/floppy.txt.
  549. gamecon.map[2|3]=
  550. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  551. support via parallel port (up to 5 devices per port)
  552. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  553. See also Documentation/input/joystick-parport.txt
  554. gamma= [HW,DRM]
  555. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  556. Format: off | on
  557. default: on
  558. gdth= [HW,SCSI]
  559. See header of drivers/scsi/gdth.c.
  560. gpt [EFI] Forces disk with valid GPT signature but
  561. invalid Protective MBR to be treated as GPT.
  562. gvp11= [HW,SCSI]
  563. hashdist= [KNL,NUMA] Large hashes allocated during boot
  564. are distributed across NUMA nodes. Defaults on
  565. for IA-64, off otherwise.
  566. Format: 0 | 1 (for off | on)
  567. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  568. hd= [EIDE] (E)IDE hard drive subsystem geometry
  569. Format: <cyl>,<head>,<sect>
  570. hd?= [HW] (E)IDE subsystem
  571. hd?lun= See Documentation/ide.txt.
  572. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  573. size of <nn>. This works even on boxes that have no
  574. highmem otherwise. This also works to reduce highmem
  575. size on bigger boxes.
  576. highres= [KNL] Enable/disable high resolution timer mode.
  577. Valid parameters: "on", "off"
  578. Default: "on"
  579. hisax= [HW,ISDN]
  580. See Documentation/isdn/README.HiSax.
  581. hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
  582. hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
  583. i8042.direct [HW] Put keyboard port into non-translated mode
  584. i8042.dumbkbd [HW] Pretend that controller can only read data from
  585. keyboard and cannot control its state
  586. (Don't attempt to blink the leds)
  587. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  588. i8042.nokbd [HW] Don't check/create keyboard port
  589. i8042.nomux [HW] Don't check presence of an active multiplexing
  590. controller
  591. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  592. controllers
  593. i8042.panicblink=
  594. [HW] Frequency with which keyboard LEDs should blink
  595. when kernel panics (default is 0.5 sec)
  596. i8042.reset [HW] Reset the controller during init and cleanup
  597. i8042.unlock [HW] Unlock (ignore) the keylock
  598. i810= [HW,DRM]
  599. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  600. indicates that the driver is running on unsupported
  601. hardware.
  602. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  603. does not match list of supported models.
  604. i8k.power_status
  605. [HW] Report power status in /proc/i8k
  606. (disabled by default)
  607. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  608. capability is set.
  609. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  610. See Documentation/mca.txt.
  611. icn= [HW,ISDN]
  612. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  613. ide= [HW] (E)IDE subsystem
  614. Format: ide=nodma or ide=doubler or ide=reverse
  615. See Documentation/ide.txt.
  616. ide?= [HW] (E)IDE subsystem
  617. Format: ide?=noprobe or chipset specific parameters.
  618. See Documentation/ide.txt.
  619. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  620. See Documentation/ide.txt.
  621. idle= [X86]
  622. Format: idle=poll or idle=mwait
  623. Poll forces a polling idle loop that can slightly improves the performance
  624. of waking up a idle CPU, but will use a lot of power and make the system
  625. run hot. Not recommended.
  626. idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
  627. to not use it because it doesn't save as much power as a normal idle
  628. loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
  629. as idle=poll.
  630. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  631. Claim all unknown PCI IDE storage controllers.
  632. ignore_loglevel [KNL]
  633. Ignore loglevel setting - this will print /all/
  634. kernel messages to the console. Useful for debugging.
  635. ihash_entries= [KNL]
  636. Set number of hash buckets for inode cache.
  637. in2000= [HW,SCSI]
  638. See header of drivers/scsi/in2000.c.
  639. init= [KNL]
  640. Format: <full_path>
  641. Run specified binary instead of /sbin/init as init
  642. process.
  643. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  644. for working out where the kernel is dying during
  645. startup.
  646. initrd= [BOOT] Specify the location of the initial ramdisk
  647. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  648. Format: <irq>
  649. inttest= [IA64]
  650. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  651. off
  652. Disable intel iommu driver.
  653. igfx_off [Default Off]
  654. By default, gfx is mapped as normal device. If a gfx
  655. device has a dedicated DMAR unit, the DMAR unit is
  656. bypassed by not enabling DMAR with this option. In
  657. this case, gfx device will use physical address for
  658. DMA.
  659. forcedac [x86_64]
  660. With this option iommu will not optimize to look
  661. for io virtual address below 32 bit forcing dual
  662. address cycle on pci bus for cards supporting greater
  663. than 32 bit addressing. The default is to look
  664. for translation below 32 bit and if not available
  665. then look in the higher range.
  666. io_delay= [X86-32,X86-64] I/O delay method
  667. 0x80
  668. Standard port 0x80 based delay
  669. 0xed
  670. Alternate port 0xed based delay (needed on some systems)
  671. udelay
  672. Simple two microseconds delay
  673. none
  674. No delay
  675. io7= [HW] IO7 for Marvel based alpha systems
  676. See comment before marvel_specify_io7 in
  677. arch/alpha/kernel/core_marvel.c.
  678. ip= [IP_PNP]
  679. See Documentation/nfsroot.txt.
  680. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  681. See comment before ip2_setup() in
  682. drivers/char/ip2/ip2base.c.
  683. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  684. See header of drivers/scsi/ips.c.
  685. ports= [IP_VS_FTP] IPVS ftp helper module
  686. Default is 21.
  687. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  688. may be specified.
  689. Format: <port>,<port>....
  690. irqfixup [HW]
  691. When an interrupt is not handled search all handlers
  692. for it. Intended to get systems with badly broken
  693. firmware running.
  694. irqpoll [HW]
  695. When an interrupt is not handled search all handlers
  696. for it. Also check all handlers each timer
  697. interrupt. Intended to get systems with badly broken
  698. firmware running.
  699. isapnp= [ISAPNP]
  700. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  701. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  702. Format:
  703. <cpu number>,...,<cpu number>
  704. or
  705. <cpu number>-<cpu number> (must be a positive range in ascending order)
  706. or a mixture
  707. <cpu number>,...,<cpu number>-<cpu number>
  708. This option can be used to specify one or more CPUs
  709. to isolate from the general SMP balancing and scheduling
  710. algorithms. The only way to move a process onto or off
  711. an "isolated" CPU is via the CPU affinity syscalls.
  712. <cpu number> begins at 0 and the maximum value is
  713. "number of CPUs in system - 1".
  714. This option is the preferred way to isolate CPUs. The
  715. alternative -- manually setting the CPU mask of all
  716. tasks in the system -- can cause problems and
  717. suboptimal load balancer performance.
  718. iucv= [HW,NET]
  719. js= [HW,JOY] Analog joystick
  720. See Documentation/input/joystick.txt.
  721. kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  722. specifies the amount of memory usable by the kernel
  723. for non-movable allocations. The requested amount is
  724. spread evenly throughout all nodes in the system. The
  725. remaining memory in each node is used for Movable
  726. pages. In the event, a node is too small to have both
  727. kernelcore and Movable pages, kernelcore pages will
  728. take priority and other nodes will have a larger number
  729. of kernelcore pages. The Movable zone is used for the
  730. allocation of pages that may be reclaimed or moved
  731. by the page migration subsystem. This means that
  732. HugeTLB pages may not be allocated from this zone.
  733. Note that allocations like PTEs-from-HighMem still
  734. use the HighMem zone if it exists, and the Normal
  735. zone if it does not.
  736. movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  737. is similar to kernelcore except it specifies the
  738. amount of memory used for migratable allocations.
  739. If both kernelcore and movablecore is specified,
  740. then kernelcore will be at *least* the specified
  741. value but may be more. If movablecore on its own
  742. is specified, the administrator must be careful
  743. that the amount of memory usable for all allocations
  744. is not too small.
  745. keepinitrd [HW,ARM]
  746. kstack=N [X86-32,X86-64] Print N words from the kernel stack
  747. in oops dumps.
  748. l2cr= [PPC]
  749. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  750. disabled it.
  751. lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
  752. C2 power state.
  753. libata.dma= [LIBATA] DMA control
  754. libata.dma=0 Disable all PATA and SATA DMA
  755. libata.dma=1 PATA and SATA Disk DMA only
  756. libata.dma=2 ATAPI (CDROM) DMA only
  757. libata.dma=4 Compact Flash DMA only
  758. Combinations also work, so libata.dma=3 enables DMA
  759. for disks and CDROMs, but not CFs.
  760. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  761. when set.
  762. Format: <int>
  763. load_ramdisk= [RAM] List of ramdisks to load from floppy
  764. See Documentation/ramdisk.txt.
  765. lockd.nlm_grace_period=P [NFS] Assign grace period.
  766. Format: <integer>
  767. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  768. Format: <integer>
  769. lockd.nlm_timeout=T [NFS] Assign timeout value.
  770. Format: <integer>
  771. lockd.nlm_udpport=M [NFS] Assign UDP port.
  772. Format: <integer>
  773. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  774. Format: <irq>
  775. loglevel= All Kernel Messages with a loglevel smaller than the
  776. console loglevel will be printed to the console. It can
  777. also be changed with klogd or other programs. The
  778. loglevels are defined as follows:
  779. 0 (KERN_EMERG) system is unusable
  780. 1 (KERN_ALERT) action must be taken immediately
  781. 2 (KERN_CRIT) critical conditions
  782. 3 (KERN_ERR) error conditions
  783. 4 (KERN_WARNING) warning conditions
  784. 5 (KERN_NOTICE) normal but significant condition
  785. 6 (KERN_INFO) informational
  786. 7 (KERN_DEBUG) debug-level messages
  787. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  788. Format: { n | nk | nM }
  789. n must be a power of two. The default size
  790. is set in the kernel config file.
  791. logo.nologo [FB] Disables display of the built-in Linux logo.
  792. This may be used to provide more screen space for
  793. kernel log messages and is useful when debugging
  794. kernel boot problems.
  795. lp=0 [LP] Specify parallel ports to use, e.g,
  796. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  797. lp=reset first parallel port). 'lp=0' disables the
  798. lp=auto printer driver. 'lp=reset' (which can be
  799. specified in addition to the ports) causes
  800. attached printers to be reset. Using
  801. lp=port1,port2,... specifies the parallel ports
  802. to associate lp devices with, starting with
  803. lp0. A port specification may be 'none' to skip
  804. that lp device, or a parport name such as
  805. 'parport0'. Specifying 'lp=auto' instead of a
  806. port specification list means that device IDs
  807. from each port should be examined, to see if
  808. an IEEE 1284-compliant printer is attached; if
  809. so, the driver will manage that printer.
  810. See also header of drivers/char/lp.c.
  811. lpj=n [KNL]
  812. Sets loops_per_jiffy to given constant, thus avoiding
  813. time-consuming boot-time autodetection (up to 250 ms per
  814. CPU). 0 enables autodetection (default). To determine
  815. the correct value for your kernel, boot with normal
  816. autodetection and see what value is printed. Note that
  817. on SMP systems the preset will be applied to all CPUs,
  818. which is likely to cause problems if your CPUs need
  819. significantly divergent settings. An incorrect value
  820. will cause delays in the kernel to be wrong, leading to
  821. unpredictable I/O errors and other breakage. Although
  822. unlikely, in the extreme case this might damage your
  823. hardware.
  824. ltpc= [NET]
  825. Format: <io>,<irq>,<dma>
  826. mac5380= [HW,SCSI] Format:
  827. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  828. mac53c9x= [HW,SCSI] Format:
  829. <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  830. machvec= [IA64] Force the use of a particular machine-vector
  831. (machvec) in a generic kernel.
  832. Example: machvec=hpzx1_swiotlb
  833. max_loop= [LOOP] Maximum number of loopback devices that can
  834. be mounted
  835. Format: <1-256>
  836. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  837. should make use of. maxcpus=n : n >= 0 limits the
  838. kernel to using 'n' processors. n=0 is a special case,
  839. it is equivalent to "nosmp", which also disables
  840. the IO APIC.
  841. max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
  842. equal to this physical address is ignored.
  843. max_luns= [SCSI] Maximum number of LUNs to probe.
  844. Should be between 1 and 2^32-1.
  845. max_report_luns=
  846. [SCSI] Maximum number of LUNs received.
  847. Should be between 1 and 16384.
  848. mca-pentium [BUGS=X86-32]
  849. mcatest= [IA-64]
  850. mce [X86-32] Machine Check Exception
  851. mce=option [X86-64] See Documentation/x86_64/boot-options.txt
  852. md= [HW] RAID subsystems devices and level
  853. See Documentation/md.txt.
  854. mdacon= [MDA]
  855. Format: <first>,<last>
  856. Specifies range of consoles to be captured by the MDA.
  857. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  858. Amount of memory to be used when the kernel is not able
  859. to see the whole system memory or for test.
  860. [X86-32] Use together with memmap= to avoid physical
  861. address space collisions. Without memmap= PCI devices
  862. could be placed at addresses belonging to unused RAM.
  863. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  864. memory.
  865. memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
  866. E820 memory map, as specified by the user.
  867. Such memmap=exactmap lines can be constructed based on
  868. BIOS output or other requirements. See the memmap=nn@ss
  869. option description.
  870. memmap=nn[KMG]@ss[KMG]
  871. [KNL] Force usage of a specific region of memory
  872. Region of memory to be used, from ss to ss+nn.
  873. memmap=nn[KMG]#ss[KMG]
  874. [KNL,ACPI] Mark specific memory as ACPI data.
  875. Region of memory to be used, from ss to ss+nn.
  876. memmap=nn[KMG]$ss[KMG]
  877. [KNL,ACPI] Mark specific memory as reserved.
  878. Region of memory to be used, from ss to ss+nn.
  879. meye.*= [HW] Set MotionEye Camera parameters
  880. See Documentation/video4linux/meye.txt.
  881. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  882. Multi-Function General Purpose Timers on AMD Geode
  883. platforms.
  884. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  885. the BIOS has incorrectly applied a workaround. TinyBIOS
  886. version 0.98 is known to be affected, 0.99 fixes the
  887. problem by letting the user disable the workaround.
  888. mga= [HW,DRM]
  889. mousedev.tap_time=
  890. [MOUSE] Maximum time between finger touching and
  891. leaving touchpad surface for touch to be considered
  892. a tap and be reported as a left button click (for
  893. touchpads working in absolute mode only).
  894. Format: <msecs>
  895. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  896. reporting absolute coordinates, such as tablets
  897. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  898. reporting absolute coordinates, such as tablets
  899. mpu401= [HW,OSS]
  900. Format: <io>,<irq>
  901. MTD_Partition= [MTD]
  902. Format: <name>,<region-number>,<size>,<offset>
  903. MTD_Region= [MTD] Format:
  904. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  905. mtdparts= [MTD]
  906. See drivers/mtd/cmdlinepart.c.
  907. mtouchusb.raw_coordinates=
  908. [HW] Make the MicroTouch USB driver use raw coordinates
  909. ('y', default) or cooked coordinates ('n')
  910. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  911. NCR_D700= [HW,SCSI]
  912. See header of drivers/scsi/NCR_D700.c.
  913. ncr5380= [HW,SCSI]
  914. ncr53c400= [HW,SCSI]
  915. ncr53c400a= [HW,SCSI]
  916. ncr53c406a= [HW,SCSI]
  917. ncr53c8xx= [HW,SCSI]
  918. netdev= [NET] Network devices parameters
  919. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  920. Note that mem_start is often overloaded to mean
  921. something different and driver-specific.
  922. This usage is only documented in each driver source
  923. file if at all.
  924. nfsaddrs= [NFS]
  925. See Documentation/nfsroot.txt.
  926. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  927. See Documentation/nfsroot.txt.
  928. nfs.callback_tcpport=
  929. [NFS] set the TCP port on which the NFSv4 callback
  930. channel should listen.
  931. nfs.idmap_cache_timeout=
  932. [NFS] set the maximum lifetime for idmapper cache
  933. entries.
  934. nfs.enable_ino64=
  935. [NFS] enable 64-bit inode numbers.
  936. If zero, the NFS client will fake up a 32-bit inode
  937. number for the readdir() and stat() syscalls instead
  938. of returning the full 64-bit number.
  939. The default is to return 64-bit inode numbers.
  940. nmi_debug= [KNL,AVR32] Specify one or more actions to take
  941. when a NMI is triggered.
  942. Format: [state][,regs][,debounce][,die]
  943. nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
  944. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  945. emulation library even if a 387 maths coprocessor
  946. is present.
  947. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  948. caches in the slab allocator. Saves per-node memory,
  949. but will impact performance.
  950. noalign [KNL,ARM]
  951. noapic [SMP,APIC] Tells the kernel to not make use of any
  952. IOAPICs that may be present in the system.
  953. nobats [PPC] Do not use BATs for mapping kernel lowmem
  954. on "Classic" PPC cores.
  955. nocache [ARM]
  956. nodelayacct [KNL] Disable per-task delay accounting
  957. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  958. noefi [X86-32,X86-64] Disable EFI runtime services support.
  959. noexec [IA-64]
  960. noexec [X86-32,X86-64]
  961. noexec=on: enable non-executable mappings (default)
  962. noexec=off: disable nn-executable mappings
  963. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  964. register save and restore. The kernel will only save
  965. legacy floating-point registers on task switch.
  966. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  967. nohlt [BUGS=ARM]
  968. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  969. instruction doesn't work correctly and not to
  970. use it.
  971. nohalt [IA-64] Tells the kernel not to use the power saving
  972. function PAL_HALT_LIGHT when idle. This increases
  973. power-consumption. On the positive side, it reduces
  974. interrupt wake-up latency, which may improve performance
  975. in certain environments such as networked servers or
  976. real-time systems.
  977. nohz= [KNL] Boottime enable/disable dynamic ticks
  978. Valid arguments: on, off
  979. Default: on
  980. noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
  981. noirqdebug [X86-32] Disables the code which attempts to detect and
  982. disable unhandled interrupt sources.
  983. no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
  984. broken timer IRQ sources.
  985. noisapnp [ISAPNP] Disables ISA PnP code.
  986. noinitrd [RAM] Tells the kernel not to load any configured
  987. initial RAM disk.
  988. nointroute [IA-64]
  989. nojitter [IA64] Disables jitter checking for ITC timers.
  990. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  991. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  992. noltlbs [PPC] Do not use large page/tlb entries for kernel
  993. lowmem mapping on PPC40x.
  994. nomca [IA-64] Disable machine check abort handling
  995. nomce [X86-32] Machine Check Exception
  996. nomfgpt [X86-32] Disable Multi-Function General Purpose
  997. Timer usage (for AMD Geode machines).
  998. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  999. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1000. with UP alternatives
  1001. noresidual [PPC] Don't use residual data on PReP machines.
  1002. noresume [SWSUSP] Disables resume and restores original swap
  1003. space.
  1004. no-scroll [VGA] Disables scrollback.
  1005. This is required for the Braillex ib80-piezo Braille
  1006. reader made by F.H. Papenmeier (Germany).
  1007. nosbagart [IA-64]
  1008. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1009. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1010. and disable the IO APIC. legacy for "maxcpus=0".
  1011. nosoftlockup [KNL] Disable the soft-lockup detector.
  1012. nosync [HW,M68K] Disables sync negotiation for all devices.
  1013. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1014. nousb [USB] Disable the USB subsystem
  1015. nowb [ARM]
  1016. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1017. one of ['zone', 'node', 'default'] can be specified
  1018. This can be set from sysctl after boot.
  1019. See Documentation/sysctl/vm.txt for details.
  1020. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1021. opl3= [HW,OSS]
  1022. Format: <io>
  1023. oprofile.timer= [HW]
  1024. Use timer interrupt instead of performance counters
  1025. osst= [HW,SCSI] SCSI Tape Driver
  1026. Format: <buffer_size>,<write_threshold>
  1027. See also Documentation/scsi/st.txt.
  1028. panic= [KNL] Kernel behaviour on panic
  1029. Format: <timeout>
  1030. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1031. connected to, default is 0.
  1032. Format: <parport#>
  1033. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1034. 0 for XT, 1 for AT (default is AT).
  1035. Format: <mode>
  1036. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1037. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1038. Use 'auto' to force the driver to use any
  1039. IRQ/DMA settings detected (the default is to
  1040. ignore detected IRQ/DMA settings because of
  1041. possible conflicts). You can specify the base
  1042. address, IRQ, and DMA settings; IRQ and DMA
  1043. should be numbers, or 'auto' (for using detected
  1044. settings on that particular port), or 'nofifo'
  1045. (to avoid using a FIFO even if it is detected).
  1046. Parallel ports are assigned in the order they
  1047. are specified on the command line, starting
  1048. with parport0.
  1049. parport_init_mode= [HW,PPT]
  1050. Configure VIA parallel port to operate in
  1051. a specific mode. This is necessary on Pegasos
  1052. computer where firmware has no options for setting
  1053. up parallel port mode and sets it to spp.
  1054. Currently this function knows 686a and 8231 chips.
  1055. Format: [spp|ps2|epp|ecp|ecpepp]
  1056. pas2= [HW,OSS] Format:
  1057. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1058. pas16= [HW,SCSI]
  1059. See header of drivers/scsi/pas16.c.
  1060. pause_on_oops=
  1061. Halt all CPUs after the first oops has been printed for
  1062. the specified number of seconds. This is to be used if
  1063. your oopses keep scrolling off the screen.
  1064. pcbit= [HW,ISDN]
  1065. pcd. [PARIDE]
  1066. See header of drivers/block/paride/pcd.c.
  1067. See also Documentation/paride.txt.
  1068. pci=option[,option...] [PCI] various PCI subsystem options:
  1069. off [X86-32] don't probe for the PCI bus
  1070. bios [X86-32] force use of PCI BIOS, don't access
  1071. the hardware directly. Use this if your machine
  1072. has a non-standard PCI host bridge.
  1073. nobios [X86-32] disallow use of PCI BIOS, only direct
  1074. hardware access methods are allowed. Use this
  1075. if you experience crashes upon bootup and you
  1076. suspect they are caused by the BIOS.
  1077. conf1 [X86-32] Force use of PCI Configuration
  1078. Mechanism 1.
  1079. conf2 [X86-32] Force use of PCI Configuration
  1080. Mechanism 2.
  1081. noaer [PCIE] If the PCIEAER kernel config parameter is
  1082. enabled, this kernel boot option can be used to
  1083. disable the use of PCIE advanced error reporting.
  1084. nodomains [PCI] Disable support for multiple PCI
  1085. root domains (aka PCI segments, in ACPI-speak).
  1086. nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
  1087. Configuration
  1088. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1089. enabled, this kernel boot option can be used to
  1090. disable the use of MSI interrupts system-wide.
  1091. nosort [X86-32] Don't sort PCI devices according to
  1092. order given by the PCI BIOS. This sorting is
  1093. done to get a device order compatible with
  1094. older kernels.
  1095. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1096. routing table. These calls are known to be buggy
  1097. on several machines and they hang the machine
  1098. when used, but on other computers it's the only
  1099. way to get the interrupt routing table. Try
  1100. this option if the kernel is unable to allocate
  1101. IRQs or discover secondary PCI buses on your
  1102. motherboard.
  1103. rom [X86-32] Assign address space to expansion ROMs.
  1104. Use with caution as certain devices share
  1105. address decoders between ROMs and other
  1106. resources.
  1107. irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
  1108. assigned automatically to PCI devices. You can
  1109. make the kernel exclude IRQs of your ISA cards
  1110. this way.
  1111. pirqaddr=0xAAAAA [X86-32] Specify the physical address
  1112. of the PIRQ table (normally generated
  1113. by the BIOS) if it is outside the
  1114. F0000h-100000h range.
  1115. lastbus=N [X86-32] Scan all buses thru bus #N. Can be
  1116. useful if the kernel is unable to find your
  1117. secondary buses and you want to tell it
  1118. explicitly which ones they are.
  1119. assign-busses [X86-32] Always assign all PCI bus
  1120. numbers ourselves, overriding
  1121. whatever the firmware may have done.
  1122. usepirqmask [X86-32] Honor the possible IRQ mask stored
  1123. in the BIOS $PIR table. This is needed on
  1124. some systems with broken BIOSes, notably
  1125. some HP Pavilion N5400 and Omnibook XE3
  1126. notebooks. This will have no effect if ACPI
  1127. IRQ routing is enabled.
  1128. noacpi [X86-32] Do not use ACPI for IRQ routing
  1129. or for PCI scanning.
  1130. use_crs [X86-32] Use _CRS for PCI resource
  1131. allocation.
  1132. routeirq Do IRQ routing for all PCI devices.
  1133. This is normally done in pci_enable_device(),
  1134. so this option is a temporary workaround
  1135. for broken drivers that don't call it.
  1136. firmware [ARM] Do not re-enumerate the bus but instead
  1137. just use the configuration from the
  1138. bootloader. This is currently used on
  1139. IXP2000 systems where the bus has to be
  1140. configured a certain way for adjunct CPUs.
  1141. noearly [X86] Don't do any early type 1 scanning.
  1142. This might help on some broken boards which
  1143. machine check when some devices' config space
  1144. is read. But various workarounds are disabled
  1145. and some IOMMU drivers will not work.
  1146. bfsort Sort PCI devices into breadth-first order.
  1147. This sorting is done to get a device
  1148. order compatible with older (<= 2.4) kernels.
  1149. nobfsort Don't sort PCI devices into breadth-first order.
  1150. cbiosize=nn[KMG] The fixed amount of bus space which is
  1151. reserved for the CardBus bridge's IO window.
  1152. The default value is 256 bytes.
  1153. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1154. reserved for the CardBus bridge's memory
  1155. window. The default value is 64 megabytes.
  1156. pcmv= [HW,PCMCIA] BadgePAD 4
  1157. pd. [PARIDE]
  1158. See Documentation/paride.txt.
  1159. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1160. boot time.
  1161. Format: { 0 | 1 }
  1162. See arch/parisc/kernel/pdc_chassis.c
  1163. pf. [PARIDE]
  1164. See Documentation/paride.txt.
  1165. pg. [PARIDE]
  1166. See Documentation/paride.txt.
  1167. pirq= [SMP,APIC] Manual mp-table setup
  1168. See Documentation/i386/IO-APIC.txt.
  1169. plip= [PPT,NET] Parallel port network link
  1170. Format: { parport<nr> | timid | 0 }
  1171. See also Documentation/parport.txt.
  1172. pnpacpi= [ACPI]
  1173. { off }
  1174. pnpbios= [ISAPNP]
  1175. { on | off | curr | res | no-curr | no-res }
  1176. pnp_reserve_irq=
  1177. [ISAPNP] Exclude IRQs for the autoconfiguration
  1178. pnp_reserve_dma=
  1179. [ISAPNP] Exclude DMAs for the autoconfiguration
  1180. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1181. Ranges are in pairs (I/O port base and size).
  1182. pnp_reserve_mem=
  1183. [ISAPNP] Exclude memory regions for the
  1184. autoconfiguration.
  1185. Ranges are in pairs (memory base and size).
  1186. print-fatal-signals=
  1187. [KNL] debug: print fatal signals
  1188. print-fatal-signals=1: print segfault info to
  1189. the kernel console.
  1190. default: off.
  1191. printk.time= Show timing data prefixed to each printk message line
  1192. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1193. profile= [KNL] Enable kernel profiling via /proc/profile
  1194. Format: [schedule,]<number>
  1195. Param: "schedule" - profile schedule points.
  1196. Param: <number> - step/bucket size as a power of 2 for
  1197. statistical time based profiling.
  1198. Param: "sleep" - profile D-state sleeping (millisecs).
  1199. Requires CONFIG_SCHEDSTATS
  1200. Param: "kvm" - profile VM exits.
  1201. processor.max_cstate= [HW,ACPI]
  1202. Limit processor to maximum C-state
  1203. max_cstate=9 overrides any DMI blacklist limit.
  1204. processor.nocst [HW,ACPI]
  1205. Ignore the _CST method to determine C-states,
  1206. instead using the legacy FADT method
  1207. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1208. before loading.
  1209. See Documentation/ramdisk.txt.
  1210. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1211. probe for; one of (bare|imps|exps|lifebook|any).
  1212. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1213. per second.
  1214. psmouse.resetafter= [HW,MOUSE]
  1215. Try to reset the device after so many bad packets
  1216. (0 = never).
  1217. psmouse.resolution=
  1218. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1219. psmouse.smartscroll=
  1220. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1221. 0 = disabled, 1 = enabled (default).
  1222. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1223. Format:
  1224. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1225. pt. [PARIDE]
  1226. See Documentation/paride.txt.
  1227. pty.legacy_count=
  1228. [KNL] Number of legacy pty's. Overwrites compiled-in
  1229. default number.
  1230. quiet [KNL] Disable most log messages
  1231. r128= [HW,DRM]
  1232. raid= [HW,RAID]
  1233. See Documentation/md.txt.
  1234. ramdisk_blocksize= [RAM]
  1235. See Documentation/ramdisk.txt.
  1236. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1237. See Documentation/ramdisk.txt.
  1238. rcupdate.blimit= [KNL,BOOT]
  1239. Set maximum number of finished RCU callbacks to process
  1240. in one batch.
  1241. rcupdate.qhimark= [KNL,BOOT]
  1242. Set threshold of queued
  1243. RCU callbacks over which batch limiting is disabled.
  1244. rcupdate.qlowmark= [KNL,BOOT]
  1245. Set threshold of queued RCU callbacks below which
  1246. batch limiting is re-enabled.
  1247. rdinit= [KNL]
  1248. Format: <full_path>
  1249. Run specified binary instead of /init from the ramdisk,
  1250. used for early userspace startup. See initrd.
  1251. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1252. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1253. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1254. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1255. reservetop= [X86-32]
  1256. Format: nn[KMG]
  1257. Reserves a hole at the top of the kernel virtual
  1258. address space.
  1259. reset_devices [KNL] Force drivers to reset the underlying device
  1260. during initialization.
  1261. resume= [SWSUSP]
  1262. Specify the partition device for software suspend
  1263. resume_offset= [SWSUSP]
  1264. Specify the offset from the beginning of the partition
  1265. given by "resume=" at which the swap header is located,
  1266. in <PAGE_SIZE> units (needed only for swap files).
  1267. See Documentation/power/swsusp-and-swap-files.txt
  1268. retain_initrd [RAM] Keep initrd memory after extraction
  1269. rhash_entries= [KNL,NET]
  1270. Set number of hash buckets for route cache
  1271. riscom8= [HW,SERIAL]
  1272. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1273. ro [KNL] Mount root device read-only on boot
  1274. root= [KNL] Root filesystem
  1275. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1276. mount the root filesystem
  1277. rootflags= [KNL] Set root filesystem mount option string
  1278. rootfstype= [KNL] Set root filesystem type
  1279. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1280. Useful for devices that are detected asynchronously
  1281. (e.g. USB and MMC devices).
  1282. root_plug.vendor_id=
  1283. [ROOTPLUG] Override the default vendor ID
  1284. root_plug.product_id=
  1285. [ROOTPLUG] Override the default product ID
  1286. root_plug.debug=
  1287. [ROOTPLUG] Enable debugging output
  1288. rw [KNL] Mount root device read-write on boot
  1289. S [KNL] Run init in single mode
  1290. sa1100ir [NET]
  1291. See drivers/net/irda/sa1100_ir.c.
  1292. sbni= [NET] Granch SBNI12 leased line adapter
  1293. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1294. Format: <io>[,<timeout>[,<isapnp>]]
  1295. scsi_debug_*= [SCSI]
  1296. See drivers/scsi/scsi_debug.c.
  1297. scsi_default_dev_flags=
  1298. [SCSI] SCSI default device flags
  1299. Format: <integer>
  1300. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1301. Format: <vendor>:<model>:<flags>
  1302. (flags are integer value)
  1303. scsi_logging_level= [SCSI] a bit mask of logging levels
  1304. See drivers/scsi/scsi_logging.h for bits. Also
  1305. settable via sysctl at dev.scsi.logging_level
  1306. (/proc/sys/dev/scsi/logging_level).
  1307. There is also a nice 'scsi_logging_level' script in the
  1308. S390-tools package, available for download at
  1309. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1310. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1311. discovered. async scans them in kernel threads,
  1312. allowing boot to proceed. none ignores them, expecting
  1313. user space to do the scan.
  1314. selinux [SELINUX] Disable or enable SELinux at boot time.
  1315. Format: { "0" | "1" }
  1316. See security/selinux/Kconfig help text.
  1317. 0 -- disable.
  1318. 1 -- enable.
  1319. Default value is set via kernel config option.
  1320. If enabled at boot time, /selinux/disable can be used
  1321. later to disable prior to initial policy load.
  1322. selinux_compat_net =
  1323. [SELINUX] Set initial selinux_compat_net flag value.
  1324. Format: { "0" | "1" }
  1325. 0 -- use new secmark-based packet controls
  1326. 1 -- use legacy packet controls
  1327. Default value is 0 (preferred).
  1328. Value can be changed at runtime via
  1329. /selinux/compat_net.
  1330. serialnumber [BUGS=X86-32]
  1331. shapers= [NET]
  1332. Maximal number of shapers.
  1333. sim710= [SCSI,HW]
  1334. See header of drivers/scsi/sim710.c.
  1335. simeth= [IA-64]
  1336. simscsi=
  1337. slram= [HW,MTD]
  1338. slub_debug[=options[,slabs]] [MM, SLUB]
  1339. Enabling slub_debug allows one to determine the
  1340. culprit if slab objects become corrupted. Enabling
  1341. slub_debug can create guard zones around objects and
  1342. may poison objects when not in use. Also tracks the
  1343. last alloc / free. For more information see
  1344. Documentation/vm/slub.txt.
  1345. slub_max_order= [MM, SLUB]
  1346. Determines the maximum allowed order for slabs.
  1347. A high setting may cause OOMs due to memory
  1348. fragmentation. For more information see
  1349. Documentation/vm/slub.txt.
  1350. slub_min_objects= [MM, SLUB]
  1351. The minimum number of objects per slab. SLUB will
  1352. increase the slab order up to slub_max_order to
  1353. generate a sufficiently large slab able to contain
  1354. the number of objects indicated. The higher the number
  1355. of objects the smaller the overhead of tracking slabs
  1356. and the less frequently locks need to be acquired.
  1357. For more information see Documentation/vm/slub.txt.
  1358. slub_min_order= [MM, SLUB]
  1359. Determines the mininum page order for slabs. Must be
  1360. lower than slub_max_order.
  1361. For more information see Documentation/vm/slub.txt.
  1362. slub_nomerge [MM, SLUB]
  1363. Disable merging of slabs with similar size. May be
  1364. necessary if there is some reason to distinguish
  1365. allocs to different slabs. Debug options disable
  1366. merging on their own.
  1367. For more information see Documentation/vm/slub.txt.
  1368. smart2= [HW]
  1369. Format: <io1>[,<io2>[,...,<io8>]]
  1370. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1371. attempt to substitute SMP alternatives once at boot.
  1372. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1373. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1374. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1375. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1376. smsc-ircc2.ircc_irq= [HW] IRQ line
  1377. smsc-ircc2.ircc_dma= [HW] DMA channel
  1378. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1379. 0: Toshiba Satellite 1800 (GP data pin select)
  1380. 1: Fast pin select (default)
  1381. 2: ATC IRMode
  1382. snd-ad1816a= [HW,ALSA]
  1383. snd-ad1848= [HW,ALSA]
  1384. snd-ali5451= [HW,ALSA]
  1385. snd-als100= [HW,ALSA]
  1386. snd-als4000= [HW,ALSA]
  1387. snd-azt2320= [HW,ALSA]
  1388. snd-cmi8330= [HW,ALSA]
  1389. snd-cmipci= [HW,ALSA]
  1390. snd-cs4231= [HW,ALSA]
  1391. snd-cs4232= [HW,ALSA]
  1392. snd-cs4236= [HW,ALSA]
  1393. snd-cs4281= [HW,ALSA]
  1394. snd-cs46xx= [HW,ALSA]
  1395. snd-dt019x= [HW,ALSA]
  1396. snd-dummy= [HW,ALSA]
  1397. snd-emu10k1= [HW,ALSA]
  1398. snd-ens1370= [HW,ALSA]
  1399. snd-ens1371= [HW,ALSA]
  1400. snd-es968= [HW,ALSA]
  1401. snd-es1688= [HW,ALSA]
  1402. snd-es18xx= [HW,ALSA]
  1403. snd-es1938= [HW,ALSA]
  1404. snd-es1968= [HW,ALSA]
  1405. snd-fm801= [HW,ALSA]
  1406. snd-gusclassic= [HW,ALSA]
  1407. snd-gusextreme= [HW,ALSA]
  1408. snd-gusmax= [HW,ALSA]
  1409. snd-hdsp= [HW,ALSA]
  1410. snd-ice1712= [HW,ALSA]
  1411. snd-intel8x0= [HW,ALSA]
  1412. snd-interwave= [HW,ALSA]
  1413. snd-interwave-stb=
  1414. [HW,ALSA]
  1415. snd-korg1212= [HW,ALSA]
  1416. snd-maestro3= [HW,ALSA]
  1417. snd-mpu401= [HW,ALSA]
  1418. snd-mtpav= [HW,ALSA]
  1419. snd-nm256= [HW,ALSA]
  1420. snd-opl3sa2= [HW,ALSA]
  1421. snd-opti92x-ad1848=
  1422. [HW,ALSA]
  1423. snd-opti92x-cs4231=
  1424. [HW,ALSA]
  1425. snd-opti93x= [HW,ALSA]
  1426. snd-pmac= [HW,ALSA]
  1427. snd-rme32= [HW,ALSA]
  1428. snd-rme96= [HW,ALSA]
  1429. snd-rme9652= [HW,ALSA]
  1430. snd-sb8= [HW,ALSA]
  1431. snd-sb16= [HW,ALSA]
  1432. snd-sbawe= [HW,ALSA]
  1433. snd-serial= [HW,ALSA]
  1434. snd-sgalaxy= [HW,ALSA]
  1435. snd-sonicvibes= [HW,ALSA]
  1436. snd-sun-amd7930=
  1437. [HW,ALSA]
  1438. snd-sun-cs4231= [HW,ALSA]
  1439. snd-trident= [HW,ALSA]
  1440. snd-usb-audio= [HW,ALSA,USB]
  1441. snd-via82xx= [HW,ALSA]
  1442. snd-virmidi= [HW,ALSA]
  1443. snd-wavefront= [HW,ALSA]
  1444. snd-ymfpci= [HW,ALSA]
  1445. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1446. See Documentation/sonypi.txt
  1447. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1448. See Documentation/specialix.txt.
  1449. spia_io_base= [HW,MTD]
  1450. spia_fio_base=
  1451. spia_pedr=
  1452. spia_peddr=
  1453. sscape= [HW,OSS]
  1454. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1455. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1456. See Documentation/scsi/st.txt.
  1457. sti= [PARISC,HW]
  1458. Format: <num>
  1459. Set the STI (builtin display/keyboard on the HP-PARISC
  1460. machines) console (graphic card) which should be used
  1461. as the initial boot-console.
  1462. See also comment in drivers/video/console/sticore.c.
  1463. sti_font= [HW]
  1464. See comment in drivers/video/console/sticore.c.
  1465. stifb= [HW]
  1466. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1467. sunrpc.pool_mode=
  1468. [NFS]
  1469. Control how the NFS server code allocates CPUs to
  1470. service thread pools. Depending on how many NICs
  1471. you have and where their interrupts are bound, this
  1472. option will affect which CPUs will do NFS serving.
  1473. Note: this parameter cannot be changed while the
  1474. NFS server is running.
  1475. auto the server chooses an appropriate mode
  1476. automatically using heuristics
  1477. global a single global pool contains all CPUs
  1478. percpu one pool for each CPU
  1479. pernode one pool for each NUMA node (equivalent
  1480. to global on non-NUMA machines)
  1481. swiotlb= [IA-64] Number of I/O TLB slabs
  1482. switches= [HW,M68k]
  1483. sym53c416= [HW,SCSI]
  1484. See header of drivers/scsi/sym53c416.c.
  1485. sysrq_always_enabled
  1486. [KNL]
  1487. Ignore sysrq setting - this boot parameter will
  1488. neutralize any effect of /proc/sys/kernel/sysrq.
  1489. Useful for debugging.
  1490. t128= [HW,SCSI]
  1491. See header of drivers/scsi/t128.c.
  1492. tdfx= [HW,DRM]
  1493. thash_entries= [KNL,NET]
  1494. Set number of hash buckets for TCP connection
  1495. thermal.act= [HW,ACPI]
  1496. -1: disable all active trip points in all thermal zones
  1497. <degrees C>: override all lowest active trip points
  1498. thermal.crt= [HW,ACPI]
  1499. -1: disable all critical trip points in all thermal zones
  1500. <degrees C>: lower all critical trip points
  1501. thermal.nocrt= [HW,ACPI]
  1502. Set to disable actions on ACPI thermal zone
  1503. critical and hot trip points.
  1504. thermal.off= [HW,ACPI]
  1505. 1: disable ACPI thermal control
  1506. thermal.psv= [HW,ACPI]
  1507. -1: disable all passive trip points
  1508. <degrees C>: override all passive trip points to this value
  1509. thermal.tzp= [HW,ACPI]
  1510. Specify global default ACPI thermal zone polling rate
  1511. <deci-seconds>: poll all this frequency
  1512. 0: no polling (default)
  1513. tipar.timeout= [HW,PPT]
  1514. Set communications timeout in tenths of a second
  1515. (default 15).
  1516. tipar.delay= [HW,PPT]
  1517. Set inter-bit delay in microseconds (default 10).
  1518. tmscsim= [HW,SCSI]
  1519. See comment before function dc390_setup() in
  1520. drivers/scsi/tmscsim.c.
  1521. tp720= [HW,PS2]
  1522. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1523. Format:
  1524. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1525. turbografx.map[2|3]= [HW,JOY]
  1526. TurboGraFX parallel port interface
  1527. Format:
  1528. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1529. See also Documentation/input/joystick-parport.txt
  1530. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1531. See header of drivers/scsi/u14-34f.c.
  1532. uart401= [HW,OSS]
  1533. Format: <io>,<irq>
  1534. uart6850= [HW,OSS]
  1535. Format: <io>,<irq>
  1536. uhci-hcd.ignore_oc=
  1537. [USB] Ignore overcurrent events (default N).
  1538. Some badly-designed motherboards generate lots of
  1539. bogus events, for ports that aren't wired to
  1540. anything. Set this parameter to avoid log spamming.
  1541. Note that genuine overcurrent events won't be
  1542. reported either.
  1543. usbcore.autosuspend=
  1544. [USB] The autosuspend time delay (in seconds) used
  1545. for newly-detected USB devices (default 2). This
  1546. is the time required before an idle device will be
  1547. autosuspended. Devices for which the delay is set
  1548. to a negative value won't be autosuspended at all.
  1549. usbhid.mousepoll=
  1550. [USBHID] The interval which mice are to be polled at.
  1551. vdso= [X86-32,SH,x86-64]
  1552. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  1553. vdso=1: enable VDSO (default)
  1554. vdso=0: disable VDSO mapping
  1555. vdso32= [X86-32,X86-64]
  1556. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  1557. vdso32=1: enable 32-bit VDSO (default)
  1558. vdso32=0: disable 32-bit VDSO mapping
  1559. vector= [IA-64,SMP]
  1560. vector=percpu: enable percpu vector domain
  1561. video= [FB] Frame buffer configuration
  1562. See Documentation/fb/modedb.txt.
  1563. vga= [BOOT,X86-32] Select a particular video mode
  1564. See Documentation/i386/boot.txt and
  1565. Documentation/svga.txt.
  1566. Use vga=ask for menu.
  1567. This is actually a boot loader parameter; the value is
  1568. passed to the kernel using a special protocol.
  1569. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1570. size of <nn>. This can be used to increase the
  1571. minimum size (128MB on x86). It can also be used to
  1572. decrease the size and leave more room for directly
  1573. mapped kernel RAM.
  1574. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1575. Format: <command>
  1576. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1577. Format: <command>
  1578. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1579. Format: <command>
  1580. waveartist= [HW,OSS]
  1581. Format: <io>,<irq>,<dma>,<dma2>
  1582. wd33c93= [HW,SCSI]
  1583. See header of drivers/scsi/wd33c93.c.
  1584. wd7000= [HW,SCSI]
  1585. See header of drivers/scsi/wd7000.c.
  1586. wdt= [WDT] Watchdog
  1587. See Documentation/watchdog/wdt.txt.
  1588. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1589. xd_geo= See header of drivers/block/xd.c.
  1590. xirc2ps_cs= [NET,PCMCIA]
  1591. Format:
  1592. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1593. norandmaps Don't use address space randomization
  1594. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
  1595. ______________________________________________________________________
  1596. TODO:
  1597. Add documentation for ALSA options.
  1598. Add more DRM drivers.