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