kernel-parameters.txt 56 KB

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  1. Kernel Parameters
  2. ~~~~~~~~~~~~~~~~~
  3. The following is a consolidated list of the kernel parameters as implemented
  4. (mostly) by the __setup() macro and sorted into English Dictionary order
  5. (defined as ignoring all punctuation and sorting digits before letters in a
  6. case insensitive manner), and with descriptions where known.
  7. Module parameters for loadable modules are specified only as the
  8. parameter name with optional '=' and value as appropriate, such as:
  9. modprobe usbcore blinkenlights=1
  10. Module parameters for modules that are built into the kernel image
  11. are specified on the kernel command line with the module name plus
  12. '.' plus parameter name, with '=' and value if appropriate, such as:
  13. usbcore.blinkenlights=1
  14. This document may not be entirely up to date and comprehensive. The command
  15. "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
  16. module. Loadable modules, after being loaded into the running kernel, also
  17. reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
  18. parameters may be changed at runtime by the command
  19. "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
  20. The parameters listed below are only valid if certain kernel build options were
  21. enabled and if respective hardware is present. The text in square brackets at
  22. the beginning of each description states the restrictions within which a
  23. parameter is applicable:
  24. ACPI ACPI support is enabled.
  25. ALSA ALSA sound support is enabled.
  26. APIC APIC support is enabled.
  27. APM Advanced Power Management support is enabled.
  28. AX25 Appropriate AX.25 support is enabled.
  29. CD Appropriate CD support is enabled.
  30. DRM Direct Rendering Management support is enabled.
  31. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
  32. EFI EFI Partitioning (GPT) is enabled
  33. EIDE EIDE/ATAPI support is enabled.
  34. FB The frame buffer device is enabled.
  35. HW Appropriate hardware is enabled.
  36. IA-32 IA-32 aka i386 architecture is enabled.
  37. IA-64 IA-64 architecture is enabled.
  38. IOSCHED More than one I/O scheduler is enabled.
  39. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  40. ISAPNP ISA PnP code is enabled.
  41. ISDN Appropriate ISDN support is enabled.
  42. JOY Appropriate joystick support is enabled.
  43. LIBATA Libata driver is enabled
  44. LP Printer support is enabled.
  45. LOOP Loopback device support is enabled.
  46. M68k M68k architecture is enabled.
  47. These options have more detailed description inside of
  48. Documentation/m68k/kernel-options.txt.
  49. MCA MCA bus support is enabled.
  50. MDA MDA console support is enabled.
  51. MOUSE Appropriate mouse support is enabled.
  52. MSI Message Signaled Interrupts (PCI).
  53. MTD MTD support is enabled.
  54. NET Appropriate network support is enabled.
  55. NUMA NUMA support is enabled.
  56. GENERIC_TIME The generic timeofday code is enabled.
  57. NFS Appropriate NFS support is enabled.
  58. OSS OSS sound support is enabled.
  59. PARIDE The ParIDE subsystem is enabled.
  60. PARISC The PA-RISC architecture is enabled.
  61. PCI PCI bus support is enabled.
  62. PCMCIA The PCMCIA subsystem is enabled.
  63. PNP Plug & Play support is enabled.
  64. PPC PowerPC architecture is enabled.
  65. PPT Parallel port support is enabled.
  66. PS2 Appropriate PS/2 support is enabled.
  67. RAM RAM disk support is enabled.
  68. S390 S390 architecture is enabled.
  69. SCSI Appropriate SCSI support is enabled.
  70. A lot of drivers has their options described inside of
  71. Documentation/scsi/.
  72. SELINUX SELinux support is enabled.
  73. SERIAL Serial support is enabled.
  74. SH SuperH architecture is enabled.
  75. SMP The kernel is an SMP kernel.
  76. SPARC Sparc architecture is enabled.
  77. SWSUSP Software suspend is enabled.
  78. TS Appropriate touchscreen support is enabled.
  79. USB USB support is enabled.
  80. USBHID USB Human Interface Device support is enabled.
  81. V4L Video For Linux support is enabled.
  82. VGA The VGA console has been enabled.
  83. VT Virtual terminal support is enabled.
  84. WDT Watchdog support is enabled.
  85. XT IBM PC/XT MFM hard disk support is enabled.
  86. X86-64 X86-64 architecture is enabled.
  87. More X86-64 boot options can be found in
  88. Documentation/x86_64/boot-options.txt .
  89. In addition, the following text indicates that the option:
  90. BUGS= Relates to possible processor bugs on the said processor.
  91. KNL Is a kernel start-up parameter.
  92. BOOT Is a boot loader parameter.
  93. Parameters denoted with BOOT are actually interpreted by the boot
  94. loader, and have no meaning to the kernel directly.
  95. Do not modify the syntax of boot loader parameters without extreme
  96. need or coordination with <Documentation/i386/boot.txt>.
  97. There are also arch-specific kernel-parameters not documented here.
  98. See for example <Documentation/x86_64/boot-options.txt>.
  99. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  100. a trailing = on the name of any parameter states that that parameter will
  101. be entered as an environment variable, whereas its absence indicates that
  102. it will appear as a kernel argument readable via /proc/cmdline by programs
  103. running once the system is up.
  104. The number of kernel parameters is not limited, but the length of the
  105. complete command line (parameters including spaces etc.) is limited to
  106. a fixed number of characters. This limit depends on the architecture
  107. and is between 256 and 4096 characters. It is defined in the file
  108. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  109. 53c7xx= [HW,SCSI] Amiga SCSI controllers
  110. See header of drivers/scsi/53c7xx.c.
  111. See also Documentation/scsi/ncr53c7xx.txt.
  112. acpi= [HW,ACPI,X86-64,i386]
  113. Advanced Configuration and Power Interface
  114. Format: { force | off | ht | strict | noirq }
  115. force -- enable ACPI if default was off
  116. off -- disable ACPI if default was on
  117. noirq -- do not use ACPI for IRQ routing
  118. ht -- run only enough ACPI to enable Hyper Threading
  119. strict -- Be less tolerant of platforms that are not
  120. strictly ACPI specification compliant.
  121. See also Documentation/pm.txt, pci=noacpi
  122. acpi_apic_instance= [ACPI, IOAPIC]
  123. Format: <int>
  124. 2: use 2nd APIC table, if available
  125. 1,0: use 1st APIC table
  126. default: 0
  127. acpi_sleep= [HW,ACPI] Sleep options
  128. Format: { s3_bios, s3_mode }
  129. See Documentation/power/video.txt
  130. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  131. Format: { level | edge | high | low }
  132. acpi_irq_balance [HW,ACPI]
  133. ACPI will balance active IRQs
  134. default in APIC mode
  135. acpi_irq_nobalance [HW,ACPI]
  136. ACPI will not move active IRQs (default)
  137. default in PIC mode
  138. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  139. use by PCI
  140. Format: <irq>,<irq>...
  141. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  142. Format: <irq>,<irq>...
  143. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  144. Format: To spoof as Windows 98: ="Microsoft Windows"
  145. acpi_osi= [HW,ACPI] empty param disables _OSI
  146. acpi_serialize [HW,ACPI] force serialization of AML methods
  147. acpi_skip_timer_override [HW,ACPI]
  148. Recognize and ignore IRQ0/pin2 Interrupt Override.
  149. For broken nForce2 BIOS resulting in XT-PIC timer.
  150. acpi_use_timer_override [HW,ACPI}
  151. Use timer override. For some broken Nvidia NF5 boards
  152. that require a timer override, but don't have
  153. HPET
  154. acpi.debug_layer= [HW,ACPI]
  155. Format: <int>
  156. Each bit of the <int> indicates an ACPI debug layer,
  157. 1: enable, 0: disable. It is useful for boot time
  158. debugging. After system has booted up, it can be set
  159. via /sys/module/acpi/parameters/debug_layer.
  160. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  161. Available bits (add the numbers together) to enable debug output
  162. for specific parts of the ACPI subsystem:
  163. 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
  164. 0x10 namespace 0x20 parser 0x40 dispatcher
  165. 0x80 executer 0x100 resources 0x200 acpica debugger
  166. 0x400 os services 0x800 acpica disassembler.
  167. The number can be in decimal or prefixed with 0x in hex.
  168. Warning: Many of these options can produce a lot of
  169. output and make your system unusable. Be very careful.
  170. acpi.debug_level= [HW,ACPI]
  171. Format: <int>
  172. Each bit of the <int> indicates an ACPI debug level,
  173. 1: enable, 0: disable. It is useful for boot time
  174. debugging. After system has booted up, it can be set
  175. via /sys/module/acpi/parameters/debug_level.
  176. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  177. Available bits (add the numbers together) to enable different
  178. debug output levels of the ACPI subsystem:
  179. 0x01 error 0x02 warn 0x04 init 0x08 debug object
  180. 0x10 info 0x20 init names 0x40 parse 0x80 load
  181. 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
  182. 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
  183. 0x10000 resources 0x20000 user requests 0x40000 package.
  184. The number can be in decimal or prefixed with 0x in hex.
  185. Warning: Many of these options can produce a lot of
  186. output and make your system unusable. Be very careful.
  187. acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
  188. acpi_generic_hotkey [HW,ACPI]
  189. Allow consolidated generic hotkey driver to
  190. override platform specific driver.
  191. See also Documentation/acpi-hotkey.txt.
  192. acpi_pm_good [IA-32,X86-64]
  193. Override the pmtimer bug detection: force the kernel
  194. to assume that this machine's pmtimer latches its value
  195. and always returns good values.
  196. enable_timer_pin_1 [i386,x86-64]
  197. Enable PIN 1 of APIC timer
  198. Can be useful to work around chipset bugs
  199. (in particular on some ATI chipsets).
  200. The kernel tries to set a reasonable default.
  201. disable_timer_pin_1 [i386,x86-64]
  202. Disable PIN 1 of APIC timer
  203. Can be useful to work around chipset bugs.
  204. ad1816= [HW,OSS]
  205. Format: <io>,<irq>,<dma>,<dma2>
  206. See also Documentation/sound/oss/AD1816.
  207. ad1848= [HW,OSS]
  208. Format: <io>,<irq>,<dma>,<dma2>,<type>
  209. adlib= [HW,OSS]
  210. Format: <io>
  211. advansys= [HW,SCSI]
  212. See header of drivers/scsi/advansys.c.
  213. advwdt= [HW,WDT] Advantech WDT
  214. Format: <iostart>,<iostop>
  215. aedsp16= [HW,OSS] Audio Excel DSP 16
  216. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  217. See also header of sound/oss/aedsp16.c.
  218. aha152x= [HW,SCSI]
  219. See Documentation/scsi/aha152x.txt.
  220. aha1542= [HW,SCSI]
  221. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  222. aic7xxx= [HW,SCSI]
  223. See Documentation/scsi/aic7xxx.txt.
  224. aic79xx= [HW,SCSI]
  225. See Documentation/scsi/aic79xx.txt.
  226. amijoy.map= [HW,JOY] Amiga joystick support
  227. Map of devices attached to JOY0DAT and JOY1DAT
  228. Format: <a>,<b>
  229. See also Documentation/kernel/input/joystick.txt
  230. analog.map= [HW,JOY] Analog joystick and gamepad support
  231. Specifies type or capabilities of an analog joystick
  232. connected to one of 16 gameports
  233. Format: <type1>,<type2>,..<type16>
  234. apc= [HW,SPARC]
  235. Power management functions (SPARCstation-4/5 + deriv.)
  236. Format: noidle
  237. Disable APC CPU standby support. SPARCstation-Fox does
  238. not play well with APC CPU idle - disable it if you have
  239. APC and your system crashes randomly.
  240. apic= [APIC,i386] Change the output verbosity whilst booting
  241. Format: { quiet (default) | verbose | debug }
  242. Change the amount of debugging information output
  243. when initialising the APIC and IO-APIC components.
  244. apm= [APM] Advanced Power Management
  245. See header of arch/i386/kernel/apm.c.
  246. applicom= [HW]
  247. Format: <mem>,<irq>
  248. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  249. Format: <io>,<irq>,<nodeID>
  250. ataflop= [HW,M68k]
  251. atarimouse= [HW,MOUSE] Atari Mouse
  252. atascsi= [HW,SCSI] Atari SCSI
  253. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  254. EzKey and similar keyboards
  255. atkbd.reset= [HW] Reset keyboard during initialization
  256. atkbd.set= [HW] Select keyboard code set
  257. Format: <int> (2 = AT (default), 3 = PS/2)
  258. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  259. keyboards
  260. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  261. Format: <bool> (0 = real, 1 = synthetic (default))
  262. atkbd.softrepeat= [HW]
  263. Use software keyboard repeat
  264. autotest [IA64]
  265. aztcd= [HW,CD] Aztech CD268 CDROM driver
  266. Format: <io>,0x79 (?)
  267. baycom_epp= [HW,AX25]
  268. Format: <io>,<mode>
  269. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  270. Format: <io>,<mode>
  271. See header of drivers/net/hamradio/baycom_par.c.
  272. baycom_ser_fdx= [HW,AX25]
  273. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  274. Format: <io>,<irq>,<mode>[,<baud>]
  275. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  276. baycom_ser_hdx= [HW,AX25]
  277. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  278. Format: <io>,<irq>,<mode>
  279. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  280. blkmtd_device= [HW,MTD]
  281. blkmtd_erasesz=
  282. blkmtd_ro=
  283. blkmtd_bs=
  284. blkmtd_count=
  285. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  286. bttv.radio= Most important insmod options are available as
  287. kernel args too.
  288. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  289. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  290. BusLogic= [HW,SCSI]
  291. See drivers/scsi/BusLogic.c, comment before function
  292. BusLogic_ParseDriverOptions().
  293. c101= [NET] Moxa C101 synchronous serial card
  294. cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
  295. Sometimes CPU hardware bugs make them report the cache
  296. size incorrectly. The kernel will attempt work arounds
  297. to fix known problems, but for some CPUs it is not
  298. possible to determine what the correct size should be.
  299. This option provides an override for these situations.
  300. cdu31a= [HW,CD]
  301. Format: <io>,<irq>[,PAS]
  302. See header of drivers/cdrom/cdu31a.c.
  303. chandev= [HW,NET] Generic channel device initialisation
  304. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  305. Format: { "0" | "1" }
  306. See security/selinux/Kconfig help text.
  307. 0 -- check protection applied by kernel (includes
  308. any implied execute protection).
  309. 1 -- check protection requested by application.
  310. Default value is set via a kernel config option.
  311. Value can be changed at runtime via
  312. /selinux/checkreqprot.
  313. clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
  314. [Deprecated]
  315. Forces specified clocksource (if available) to be used
  316. when calculating gettimeofday(). If specified
  317. clocksource is not available, it defaults to PIT.
  318. Format: { pit | tsc | cyclone | pmtmr }
  319. code_bytes [IA32] How many bytes of object code to print in an
  320. oops report.
  321. Range: 0 - 8192
  322. Default: 64
  323. disable_8254_timer
  324. enable_8254_timer
  325. [IA32/X86_64] Disable/Enable interrupt 0 timer routing
  326. over the 8254 in addition to over the IO-APIC. The
  327. kernel tries to set a sensible default.
  328. hpet= [IA-32,HPET] option to disable HPET and use PIT.
  329. Format: disable
  330. cm206= [HW,CD]
  331. Format: { auto | [<io>,][<irq>] }
  332. com20020= [HW,NET] ARCnet - COM20020 chipset
  333. Format:
  334. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  335. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  336. Format: <io>[,<irq>]
  337. com90xx= [HW,NET]
  338. ARCnet - COM90xx chipset (memory-mapped buffers)
  339. Format: <io>[,<irq>[,<memstart>]]
  340. condev= [HW,S390] console device
  341. conmode=
  342. console= [KNL] Output console device and options.
  343. tty<n> Use the virtual console device <n>.
  344. ttyS<n>[,options]
  345. ttyUSB0[,options]
  346. Use the specified serial port. The options are of
  347. the form "bbbbpnf", where "bbbb" is the baud rate,
  348. "p" is parity ("n", "o", or "e"), "n" is number of
  349. bits, and "f" is flow control ("r" for RTS or
  350. omit it). Default is "9600n8".
  351. See Documentation/serial-console.txt for more
  352. information. See
  353. Documentation/networking/netconsole.txt for an
  354. alternative.
  355. uart,io,<addr>[,options]
  356. uart,mmio,<addr>[,options]
  357. Start an early, polled-mode console on the 8250/16550
  358. UART at the specified I/O port or MMIO address,
  359. switching to the matching ttyS device later. The
  360. options are the same as for ttyS, above.
  361. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  362. Format:
  363. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  364. cpia_pp= [HW,PPT]
  365. Format: { parport<nr> | auto | none }
  366. crashkernel=nn[KMG]@ss[KMG]
  367. [KNL] Reserve a chunk of physical memory to
  368. hold a kernel to switch to with kexec on panic.
  369. cs4232= [HW,OSS]
  370. Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
  371. cs89x0_dma= [HW,NET]
  372. Format: <dma>
  373. cs89x0_media= [HW,NET]
  374. Format: { rj45 | aui | bnc }
  375. cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
  376. dasd= [HW,NET]
  377. See header of drivers/s390/block/dasd_devmap.c.
  378. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  379. (one device per port)
  380. Format: <port#>,<type>
  381. See also Documentation/input/joystick-parport.txt
  382. debug [KNL] Enable kernel debugging (events log level).
  383. debug_locks_verbose=
  384. [KNL] verbose self-tests
  385. Format=<0|1>
  386. Print debugging info while doing the locking API
  387. self-tests.
  388. We default to 0 (no extra messages), setting it to
  389. 1 will print _a lot_ more information - normally
  390. only useful to kernel developers.
  391. decnet= [HW,NET]
  392. Format: <area>[,<node>]
  393. See also Documentation/networking/decnet.txt.
  394. dhash_entries= [KNL]
  395. Set number of hash buckets for dentry cache.
  396. digi= [HW,SERIAL]
  397. IO parameters + enable/disable command.
  398. digiepca= [HW,SERIAL]
  399. See drivers/char/README.epca and
  400. Documentation/digiepca.txt.
  401. dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
  402. support available.
  403. Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
  404. dmasound= [HW,OSS] Sound subsystem buffers
  405. dscc4.setup= [NET]
  406. dtc3181e= [HW,SCSI]
  407. earlyprintk= [IA-32,X86-64,SH]
  408. earlyprintk=vga
  409. earlyprintk=serial[,ttySn[,baudrate]]
  410. Append ",keep" to not disable it when the real console
  411. takes over.
  412. Only vga or serial at a time, not both.
  413. Currently only ttyS0 and ttyS1 are supported.
  414. Interaction with the standard serial driver is not
  415. very good.
  416. The VGA output is eventually overwritten by the real
  417. console.
  418. eata= [HW,SCSI]
  419. ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
  420. Format: <int>
  421. 0: polling mode
  422. non-0: interrupt mode (default)
  423. eda= [HW,PS2]
  424. edb= [HW,PS2]
  425. edd= [EDD]
  426. Format: {"of[f]" | "sk[ipmbr]"}
  427. See comment in arch/i386/boot/edd.S
  428. eicon= [HW,ISDN]
  429. Format: <id>,<membase>,<irq>
  430. eisa_irq_edge= [PARISC,HW]
  431. See header of drivers/parisc/eisa.c.
  432. elanfreq= [IA-32]
  433. See comment before function elanfreq_setup() in
  434. arch/i386/kernel/cpu/cpufreq/elanfreq.c.
  435. elevator= [IOSCHED]
  436. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  437. See Documentation/block/as-iosched.txt and
  438. Documentation/block/deadline-iosched.txt for details.
  439. elfcorehdr= [IA-32, X86_64]
  440. Specifies physical address of start of kernel core
  441. image elf header. Generally kexec loader will
  442. pass this option to capture kernel.
  443. See Documentation/kdump/kdump.txt for details.
  444. enforcing [SELINUX] Set initial enforcing status.
  445. Format: {"0" | "1"}
  446. See security/selinux/Kconfig help text.
  447. 0 -- permissive (log only, no denials).
  448. 1 -- enforcing (deny and log).
  449. Default value is 0.
  450. Value can be changed at runtime via /selinux/enforce.
  451. es1371= [HW,OSS]
  452. Format: <spdif>,[<nomix>,[<amplifier>]]
  453. See also header of sound/oss/es1371.c.
  454. ether= [HW,NET] Ethernet cards parameters
  455. This option is obsoleted by the "netdev=" option, which
  456. has equivalent usage. See its documentation for details.
  457. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  458. Format: <io>[,<irq>]
  459. failslab=
  460. fail_page_alloc=
  461. fail_make_request=[KNL]
  462. General fault injection mechanism.
  463. Format: <interval>,<probability>,<space>,<times>
  464. See also /Documentation/fault-injection/.
  465. fd_mcs= [HW,SCSI]
  466. See header of drivers/scsi/fd_mcs.c.
  467. fdomain= [HW,SCSI]
  468. See header of drivers/scsi/fdomain.c.
  469. floppy= [HW]
  470. See Documentation/floppy.txt.
  471. gamecon.map[2|3]=
  472. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  473. support via parallel port (up to 5 devices per port)
  474. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  475. See also Documentation/input/joystick-parport.txt
  476. gamma= [HW,DRM]
  477. gdth= [HW,SCSI]
  478. See header of drivers/scsi/gdth.c.
  479. gpt [EFI] Forces disk with valid GPT signature but
  480. invalid Protective MBR to be treated as GPT.
  481. gscd= [HW,CD]
  482. Format: <io>
  483. gvp11= [HW,SCSI]
  484. hashdist= [KNL,NUMA] Large hashes allocated during boot
  485. are distributed across NUMA nodes. Defaults on
  486. for IA-64, off otherwise.
  487. Format: 0 | 1 (for off | on)
  488. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  489. hd= [EIDE] (E)IDE hard drive subsystem geometry
  490. Format: <cyl>,<head>,<sect>
  491. hd?= [HW] (E)IDE subsystem
  492. hd?lun= See Documentation/ide.txt.
  493. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  494. size of <nn>. This works even on boxes that have no
  495. highmem otherwise. This also works to reduce highmem
  496. size on bigger boxes.
  497. highres= [KNL] Enable/disable high resolution timer mode.
  498. Valid parameters: "on", "off"
  499. Default: "on"
  500. hisax= [HW,ISDN]
  501. See Documentation/isdn/README.HiSax.
  502. hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
  503. i8042.direct [HW] Put keyboard port into non-translated mode
  504. i8042.dumbkbd [HW] Pretend that controller can only read data from
  505. keyboard and cannot control its state
  506. (Don't attempt to blink the leds)
  507. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  508. i8042.nokbd [HW] Don't check/create keyboard port
  509. i8042.nomux [HW] Don't check presence of an active multiplexing
  510. controller
  511. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  512. controllers
  513. i8042.panicblink=
  514. [HW] Frequency with which keyboard LEDs should blink
  515. when kernel panics (default is 0.5 sec)
  516. i8042.reset [HW] Reset the controller during init and cleanup
  517. i8042.unlock [HW] Unlock (ignore) the keylock
  518. i810= [HW,DRM]
  519. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  520. indicates that the driver is running on unsupported
  521. hardware.
  522. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  523. does not match list of supported models.
  524. i8k.power_status
  525. [HW] Report power status in /proc/i8k
  526. (disabled by default)
  527. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  528. capability is set.
  529. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  530. See Documentation/mca.txt.
  531. icn= [HW,ISDN]
  532. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  533. ide= [HW] (E)IDE subsystem
  534. Format: ide=nodma or ide=doubler or ide=reverse
  535. See Documentation/ide.txt.
  536. ide?= [HW] (E)IDE subsystem
  537. Format: ide?=noprobe or chipset specific parameters.
  538. See Documentation/ide.txt.
  539. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  540. See Documentation/ide.txt.
  541. idle= [X86]
  542. Format: idle=poll or idle=mwait
  543. Poll forces a polling idle loop that can slightly improves the performance
  544. of waking up a idle CPU, but will use a lot of power and make the system
  545. run hot. Not recommended.
  546. idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
  547. to not use it because it doesn't save as much power as a normal idle
  548. loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
  549. as idle=poll.
  550. ignore_loglevel [KNL]
  551. Ignore loglevel setting - this will print /all/
  552. kernel messages to the console. Useful for debugging.
  553. ihash_entries= [KNL]
  554. Set number of hash buckets for inode cache.
  555. in2000= [HW,SCSI]
  556. See header of drivers/scsi/in2000.c.
  557. init= [KNL]
  558. Format: <full_path>
  559. Run specified binary instead of /sbin/init as init
  560. process.
  561. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  562. for working out where the kernel is dying during
  563. startup.
  564. initrd= [BOOT] Specify the location of the initial ramdisk
  565. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  566. Format: <irq>
  567. combined_mode= [HW] control which driver uses IDE ports in combined
  568. mode: legacy IDE driver, libata, or both
  569. (in the libata case, libata.atapi_enabled=1 may be
  570. useful as well). Note that using the ide or libata
  571. options may affect your device naming (e.g. by
  572. changing hdc to sdb).
  573. Format: combined (default), ide, or libata
  574. inttest= [IA64]
  575. io7= [HW] IO7 for Marvel based alpha systems
  576. See comment before marvel_specify_io7 in
  577. arch/alpha/kernel/core_marvel.c.
  578. ip= [IP_PNP]
  579. See Documentation/nfsroot.txt.
  580. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  581. See comment before ip2_setup() in drivers/char/ip2.c.
  582. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  583. See header of drivers/scsi/ips.c.
  584. ports= [IP_VS_FTP] IPVS ftp helper module
  585. Default is 21.
  586. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  587. may be specified.
  588. Format: <port>,<port>....
  589. irqfixup [HW]
  590. When an interrupt is not handled search all handlers
  591. for it. Intended to get systems with badly broken
  592. firmware running.
  593. irqpoll [HW]
  594. When an interrupt is not handled search all handlers
  595. for it. Also check all handlers each timer
  596. interrupt. Intended to get systems with badly broken
  597. firmware running.
  598. isapnp= [ISAPNP]
  599. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  600. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  601. Format:
  602. <cpu number>,...,<cpu number>
  603. or
  604. <cpu number>-<cpu number> (must be a positive range in ascending order)
  605. or a mixture
  606. <cpu number>,...,<cpu number>-<cpu number>
  607. This option can be used to specify one or more CPUs
  608. to isolate from the general SMP balancing and scheduling
  609. algorithms. The only way to move a process onto or off
  610. an "isolated" CPU is via the CPU affinity syscalls.
  611. <cpu number> begins at 0 and the maximum value is
  612. "number of CPUs in system - 1".
  613. This option is the preferred way to isolate CPUs. The
  614. alternative -- manually setting the CPU mask of all
  615. tasks in the system -- can cause problems and
  616. suboptimal load balancer performance.
  617. isp16= [HW,CD]
  618. Format: <io>,<irq>,<dma>,<setup>
  619. iucv= [HW,NET]
  620. js= [HW,JOY] Analog joystick
  621. See Documentation/input/joystick.txt.
  622. keepinitrd [HW,ARM]
  623. kstack=N [IA-32,X86-64] Print N words from the kernel stack
  624. in oops dumps.
  625. l2cr= [PPC]
  626. lapic [IA-32,APIC] Enable the local APIC even if BIOS
  627. disabled it.
  628. lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
  629. C2 power state.
  630. lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
  631. Format: addr:<io>,irq:<irq>
  632. llsc*= [IA64] See function print_params() in
  633. arch/ia64/sn/kernel/llsc4.c.
  634. load_ramdisk= [RAM] List of ramdisks to load from floppy
  635. See Documentation/ramdisk.txt.
  636. lockd.nlm_grace_period=P [NFS] Assign grace period.
  637. Format: <integer>
  638. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  639. Format: <integer>
  640. lockd.nlm_timeout=T [NFS] Assign timeout value.
  641. Format: <integer>
  642. lockd.nlm_udpport=M [NFS] Assign UDP port.
  643. Format: <integer>
  644. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  645. Format: <irq>
  646. loglevel= All Kernel Messages with a loglevel smaller than the
  647. console loglevel will be printed to the console. It can
  648. also be changed with klogd or other programs. The
  649. loglevels are defined as follows:
  650. 0 (KERN_EMERG) system is unusable
  651. 1 (KERN_ALERT) action must be taken immediately
  652. 2 (KERN_CRIT) critical conditions
  653. 3 (KERN_ERR) error conditions
  654. 4 (KERN_WARNING) warning conditions
  655. 5 (KERN_NOTICE) normal but significant condition
  656. 6 (KERN_INFO) informational
  657. 7 (KERN_DEBUG) debug-level messages
  658. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  659. Format: { n | nk | nM }
  660. n must be a power of two. The default size
  661. is set in the kernel config file.
  662. lp=0 [LP] Specify parallel ports to use, e.g,
  663. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  664. lp=reset first parallel port). 'lp=0' disables the
  665. lp=auto printer driver. 'lp=reset' (which can be
  666. specified in addition to the ports) causes
  667. attached printers to be reset. Using
  668. lp=port1,port2,... specifies the parallel ports
  669. to associate lp devices with, starting with
  670. lp0. A port specification may be 'none' to skip
  671. that lp device, or a parport name such as
  672. 'parport0'. Specifying 'lp=auto' instead of a
  673. port specification list means that device IDs
  674. from each port should be examined, to see if
  675. an IEEE 1284-compliant printer is attached; if
  676. so, the driver will manage that printer.
  677. See also header of drivers/char/lp.c.
  678. lpj=n [KNL]
  679. Sets loops_per_jiffy to given constant, thus avoiding
  680. time-consuming boot-time autodetection (up to 250 ms per
  681. CPU). 0 enables autodetection (default). To determine
  682. the correct value for your kernel, boot with normal
  683. autodetection and see what value is printed. Note that
  684. on SMP systems the preset will be applied to all CPUs,
  685. which is likely to cause problems if your CPUs need
  686. significantly divergent settings. An incorrect value
  687. will cause delays in the kernel to be wrong, leading to
  688. unpredictable I/O errors and other breakage. Although
  689. unlikely, in the extreme case this might damage your
  690. hardware.
  691. ltpc= [NET]
  692. Format: <io>,<irq>,<dma>
  693. mac5380= [HW,SCSI] Format:
  694. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  695. mac53c9x= [HW,SCSI] Format:
  696. <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  697. machvec= [IA64] Force the use of a particular machine-vector
  698. (machvec) in a generic kernel.
  699. Example: machvec=hpzx1_swiotlb
  700. max_loop= [LOOP] Maximum number of loopback devices that can
  701. be mounted
  702. Format: <1-256>
  703. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  704. should make use of.
  705. Using "nosmp" or "maxcpus=0" will disable SMP
  706. entirely (the MPS table probe still happens, though).
  707. A command-line option of "maxcpus=<NUM>", where <NUM>
  708. is an integer greater than 0, limits the maximum number
  709. of CPUs activated in SMP mode to <NUM>.
  710. Using "maxcpus=1" on an SMP kernel is the trivial
  711. case of an SMP kernel with only one CPU.
  712. max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
  713. equal to this physical address is ignored.
  714. max_luns= [SCSI] Maximum number of LUNs to probe.
  715. Should be between 1 and 2^32-1.
  716. max_report_luns=
  717. [SCSI] Maximum number of LUNs received.
  718. Should be between 1 and 16384.
  719. mca-pentium [BUGS=IA-32]
  720. mcatest= [IA-64]
  721. mcd= [HW,CD]
  722. Format: <port>,<irq>,<mitsumi_bug_93_wait>
  723. mcdx= [HW,CD]
  724. mce [IA-32] Machine Check Exception
  725. md= [HW] RAID subsystems devices and level
  726. See Documentation/md.txt.
  727. mdacon= [MDA]
  728. Format: <first>,<last>
  729. Specifies range of consoles to be captured by the MDA.
  730. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  731. Amount of memory to be used when the kernel is not able
  732. to see the whole system memory or for test.
  733. [IA-32] Use together with memmap= to avoid physical
  734. address space collisions. Without memmap= PCI devices
  735. could be placed at addresses belonging to unused RAM.
  736. mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
  737. memory.
  738. memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
  739. E820 memory map, as specified by the user.
  740. Such memmap=exactmap lines can be constructed based on
  741. BIOS output or other requirements. See the memmap=nn@ss
  742. option description.
  743. memmap=nn[KMG]@ss[KMG]
  744. [KNL] Force usage of a specific region of memory
  745. Region of memory to be used, from ss to ss+nn.
  746. memmap=nn[KMG]#ss[KMG]
  747. [KNL,ACPI] Mark specific memory as ACPI data.
  748. Region of memory to be used, from ss to ss+nn.
  749. memmap=nn[KMG]$ss[KMG]
  750. [KNL,ACPI] Mark specific memory as reserved.
  751. Region of memory to be used, from ss to ss+nn.
  752. meye.*= [HW] Set MotionEye Camera parameters
  753. See Documentation/video4linux/meye.txt.
  754. mga= [HW,DRM]
  755. migration_cost=
  756. [KNL,SMP] debug: override scheduler migration costs
  757. Format: <level-1-usecs>,<level-2-usecs>,...
  758. This debugging option can be used to override the
  759. default scheduler migration cost matrix. The numbers
  760. are indexed by 'CPU domain distance'.
  761. E.g. migration_cost=1000,2000,3000 on an SMT NUMA
  762. box will set up an intra-core migration cost of
  763. 1 msec, an inter-core migration cost of 2 msecs,
  764. and an inter-node migration cost of 3 msecs.
  765. WARNING: using the wrong values here can break
  766. scheduler performance, so it's only for scheduler
  767. development purposes, not production environments.
  768. migration_debug=
  769. [KNL,SMP] migration cost auto-detect verbosity
  770. Format=<0|1|2>
  771. If a system's migration matrix reported at bootup
  772. seems erroneous then this option can be used to
  773. increase verbosity of the detection process.
  774. We default to 0 (no extra messages), 1 will print
  775. some more information, and 2 will be really
  776. verbose (probably only useful if you also have a
  777. serial console attached to the system).
  778. migration_factor=
  779. [KNL,SMP] multiply/divide migration costs by a factor
  780. Format=<percent>
  781. This debug option can be used to proportionally
  782. increase or decrease the auto-detected migration
  783. costs for all entries of the migration matrix.
  784. E.g. migration_factor=150 will increase migration
  785. costs by 50%. (and thus the scheduler will be less
  786. eager migrating cache-hot tasks)
  787. migration_factor=80 will decrease migration costs
  788. by 20%. (thus the scheduler will be more eager to
  789. migrate tasks)
  790. WARNING: using the wrong values here can break
  791. scheduler performance, so it's only for scheduler
  792. development purposes, not production environments.
  793. mousedev.tap_time=
  794. [MOUSE] Maximum time between finger touching and
  795. leaving touchpad surface for touch to be considered
  796. a tap and be reported as a left button click (for
  797. touchpads working in absolute mode only).
  798. Format: <msecs>
  799. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  800. reporting absolute coordinates, such as tablets
  801. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  802. reporting absolute coordinates, such as tablets
  803. mpu401= [HW,OSS]
  804. Format: <io>,<irq>
  805. MTD_Partition= [MTD]
  806. Format: <name>,<region-number>,<size>,<offset>
  807. MTD_Region= [MTD] Format:
  808. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  809. mtdparts= [MTD]
  810. See drivers/mtd/cmdline.c.
  811. mtouchusb.raw_coordinates=
  812. [HW] Make the MicroTouch USB driver use raw coordinates
  813. ('y', default) or cooked coordinates ('n')
  814. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  815. NCR_D700= [HW,SCSI]
  816. See header of drivers/scsi/NCR_D700.c.
  817. ncr5380= [HW,SCSI]
  818. ncr53c400= [HW,SCSI]
  819. ncr53c400a= [HW,SCSI]
  820. ncr53c406a= [HW,SCSI]
  821. ncr53c8xx= [HW,SCSI]
  822. netdev= [NET] Network devices parameters
  823. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  824. Note that mem_start is often overloaded to mean
  825. something different and driver-specific.
  826. This usage is only documented in each driver source
  827. file if at all.
  828. nfsaddrs= [NFS]
  829. See Documentation/nfsroot.txt.
  830. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  831. See Documentation/nfsroot.txt.
  832. nfs.callback_tcpport=
  833. [NFS] set the TCP port on which the NFSv4 callback
  834. channel should listen.
  835. nfs.idmap_cache_timeout=
  836. [NFS] set the maximum lifetime for idmapper cache
  837. entries.
  838. nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
  839. no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
  840. emulation library even if a 387 maths coprocessor
  841. is present.
  842. noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  843. when set.
  844. Format: <int>
  845. noaliencache [MM, NUMA] Disables the allcoation of alien caches in
  846. the slab allocator. Saves per-node memory, but will
  847. impact performance on real NUMA hardware.
  848. noalign [KNL,ARM]
  849. noapic [SMP,APIC] Tells the kernel to not make use of any
  850. IOAPICs that may be present in the system.
  851. noasync [HW,M68K] Disables async and sync negotiation for
  852. all devices.
  853. nobats [PPC] Do not use BATs for mapping kernel lowmem
  854. on "Classic" PPC cores.
  855. nocache [ARM]
  856. nodelayacct [KNL] Disable per-task delay accounting
  857. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  858. noexec [IA-64]
  859. noexec [IA-32,X86-64]
  860. noexec=on: enable non-executable mappings (default)
  861. noexec=off: disable nn-executable mappings
  862. nofxsr [BUGS=IA-32] Disables x86 floating point extended
  863. register save and restore. The kernel will only save
  864. legacy floating-point registers on task switch.
  865. nohlt [BUGS=ARM]
  866. no-hlt [BUGS=IA-32] Tells the kernel that the hlt
  867. instruction doesn't work correctly and not to
  868. use it.
  869. nohalt [IA-64] Tells the kernel not to use the power saving
  870. function PAL_HALT_LIGHT when idle. This increases
  871. power-consumption. On the positive side, it reduces
  872. interrupt wake-up latency, which may improve performance
  873. in certain environments such as networked servers or
  874. real-time systems.
  875. nohz= [KNL] Boottime enable/disable dynamic ticks
  876. Valid arguments: on, off
  877. Default: on
  878. noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
  879. noirqdebug [IA-32] Disables the code which attempts to detect and
  880. disable unhandled interrupt sources.
  881. no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
  882. broken timer IRQ sources.
  883. noisapnp [ISAPNP] Disables ISA PnP code.
  884. noinitrd [RAM] Tells the kernel not to load any configured
  885. initial RAM disk.
  886. nointroute [IA-64]
  887. nolapic [IA-32,APIC] Do not enable or use the local APIC.
  888. nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
  889. noltlbs [PPC] Do not use large page/tlb entries for kernel
  890. lowmem mapping on PPC40x.
  891. nomca [IA-64] Disable machine check abort handling
  892. nomce [IA-32] Machine Check Exception
  893. noresidual [PPC] Don't use residual data on PReP machines.
  894. noresume [SWSUSP] Disables resume and restores original swap
  895. space.
  896. no-scroll [VGA] Disables scrollback.
  897. This is required for the Braillex ib80-piezo Braille
  898. reader made by F.H. Papenmeier (Germany).
  899. nosbagart [IA-64]
  900. nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
  901. nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
  902. nosync [HW,M68K] Disables sync negotiation for all devices.
  903. notsc [BUGS=IA-32] Disable Time Stamp Counter
  904. nousb [USB] Disable the USB subsystem
  905. nowb [ARM]
  906. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  907. opl3= [HW,OSS]
  908. Format: <io>
  909. opl3sa2= [HW,OSS] Format:
  910. <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
  911. oprofile.timer= [HW]
  912. Use timer interrupt instead of performance counters
  913. optcd= [HW,CD]
  914. Format: <io>
  915. osst= [HW,SCSI] SCSI Tape Driver
  916. Format: <buffer_size>,<write_threshold>
  917. See also Documentation/scsi/st.txt.
  918. panic= [KNL] Kernel behaviour on panic
  919. Format: <timeout>
  920. parkbd.port= [HW] Parallel port number the keyboard adapter is
  921. connected to, default is 0.
  922. Format: <parport#>
  923. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  924. 0 for XT, 1 for AT (default is AT).
  925. Format: <mode>
  926. parport= [HW,PPT] Specify parallel ports. 0 disables.
  927. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  928. Use 'auto' to force the driver to use any
  929. IRQ/DMA settings detected (the default is to
  930. ignore detected IRQ/DMA settings because of
  931. possible conflicts). You can specify the base
  932. address, IRQ, and DMA settings; IRQ and DMA
  933. should be numbers, or 'auto' (for using detected
  934. settings on that particular port), or 'nofifo'
  935. (to avoid using a FIFO even if it is detected).
  936. Parallel ports are assigned in the order they
  937. are specified on the command line, starting
  938. with parport0.
  939. parport_init_mode= [HW,PPT]
  940. Configure VIA parallel port to operate in
  941. a specific mode. This is necessary on Pegasos
  942. computer where firmware has no options for setting
  943. up parallel port mode and sets it to spp.
  944. Currently this function knows 686a and 8231 chips.
  945. Format: [spp|ps2|epp|ecp|ecpepp]
  946. pas2= [HW,OSS] Format:
  947. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  948. pas16= [HW,SCSI]
  949. See header of drivers/scsi/pas16.c.
  950. pause_on_oops=
  951. Halt all CPUs after the first oops has been printed for
  952. the specified number of seconds. This is to be used if
  953. your oopses keep scrolling off the screen.
  954. pcbit= [HW,ISDN]
  955. pcd. [PARIDE]
  956. See header of drivers/block/paride/pcd.c.
  957. See also Documentation/paride.txt.
  958. pci=option[,option...] [PCI] various PCI subsystem options:
  959. off [IA-32] don't probe for the PCI bus
  960. bios [IA-32] force use of PCI BIOS, don't access
  961. the hardware directly. Use this if your machine
  962. has a non-standard PCI host bridge.
  963. nobios [IA-32] disallow use of PCI BIOS, only direct
  964. hardware access methods are allowed. Use this
  965. if you experience crashes upon bootup and you
  966. suspect they are caused by the BIOS.
  967. conf1 [IA-32] Force use of PCI Configuration
  968. Mechanism 1.
  969. conf2 [IA-32] Force use of PCI Configuration
  970. Mechanism 2.
  971. nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
  972. Configuration
  973. nomsi [MSI] If the PCI_MSI kernel config parameter is
  974. enabled, this kernel boot option can be used to
  975. disable the use of MSI interrupts system-wide.
  976. nosort [IA-32] Don't sort PCI devices according to
  977. order given by the PCI BIOS. This sorting is
  978. done to get a device order compatible with
  979. older kernels.
  980. biosirq [IA-32] Use PCI BIOS calls to get the interrupt
  981. routing table. These calls are known to be buggy
  982. on several machines and they hang the machine
  983. when used, but on other computers it's the only
  984. way to get the interrupt routing table. Try
  985. this option if the kernel is unable to allocate
  986. IRQs or discover secondary PCI buses on your
  987. motherboard.
  988. rom [IA-32] Assign address space to expansion ROMs.
  989. Use with caution as certain devices share
  990. address decoders between ROMs and other
  991. resources.
  992. irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
  993. assigned automatically to PCI devices. You can
  994. make the kernel exclude IRQs of your ISA cards
  995. this way.
  996. pirqaddr=0xAAAAA [IA-32] Specify the physical address
  997. of the PIRQ table (normally generated
  998. by the BIOS) if it is outside the
  999. F0000h-100000h range.
  1000. lastbus=N [IA-32] Scan all buses thru bus #N. Can be
  1001. useful if the kernel is unable to find your
  1002. secondary buses and you want to tell it
  1003. explicitly which ones they are.
  1004. assign-busses [IA-32] Always assign all PCI bus
  1005. numbers ourselves, overriding
  1006. whatever the firmware may have done.
  1007. usepirqmask [IA-32] Honor the possible IRQ mask stored
  1008. in the BIOS $PIR table. This is needed on
  1009. some systems with broken BIOSes, notably
  1010. some HP Pavilion N5400 and Omnibook XE3
  1011. notebooks. This will have no effect if ACPI
  1012. IRQ routing is enabled.
  1013. noacpi [IA-32] Do not use ACPI for IRQ routing
  1014. or for PCI scanning.
  1015. routeirq Do IRQ routing for all PCI devices.
  1016. This is normally done in pci_enable_device(),
  1017. so this option is a temporary workaround
  1018. for broken drivers that don't call it.
  1019. firmware [ARM] Do not re-enumerate the bus but instead
  1020. just use the configuration from the
  1021. bootloader. This is currently used on
  1022. IXP2000 systems where the bus has to be
  1023. configured a certain way for adjunct CPUs.
  1024. noearly [X86] Don't do any early type 1 scanning.
  1025. This might help on some broken boards which
  1026. machine check when some devices' config space
  1027. is read. But various workarounds are disabled
  1028. and some IOMMU drivers will not work.
  1029. bfsort Sort PCI devices into breadth-first order.
  1030. This sorting is done to get a device
  1031. order compatible with older (<= 2.4) kernels.
  1032. nobfsort Don't sort PCI devices into breadth-first order.
  1033. cbiosize=nn[KMG] The fixed amount of bus space which is
  1034. reserved for the CardBus bridge's IO window.
  1035. The default value is 256 bytes.
  1036. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1037. reserved for the CardBus bridge's memory
  1038. window. The default value is 64 megabytes.
  1039. pcmv= [HW,PCMCIA] BadgePAD 4
  1040. pd. [PARIDE]
  1041. See Documentation/paride.txt.
  1042. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1043. boot time.
  1044. Format: { 0 | 1 }
  1045. See arch/parisc/kernel/pdc_chassis.c
  1046. pf. [PARIDE]
  1047. See Documentation/paride.txt.
  1048. pg. [PARIDE]
  1049. See Documentation/paride.txt.
  1050. pirq= [SMP,APIC] Manual mp-table setup
  1051. See Documentation/i386/IO-APIC.txt.
  1052. plip= [PPT,NET] Parallel port network link
  1053. Format: { parport<nr> | timid | 0 }
  1054. See also Documentation/parport.txt.
  1055. pnpacpi= [ACPI]
  1056. { off }
  1057. pnpbios= [ISAPNP]
  1058. { on | off | curr | res | no-curr | no-res }
  1059. pnp_reserve_irq=
  1060. [ISAPNP] Exclude IRQs for the autoconfiguration
  1061. pnp_reserve_dma=
  1062. [ISAPNP] Exclude DMAs for the autoconfiguration
  1063. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1064. Ranges are in pairs (I/O port base and size).
  1065. pnp_reserve_mem=
  1066. [ISAPNP] Exclude memory regions for the
  1067. autoconfiguration.
  1068. Ranges are in pairs (memory base and size).
  1069. profile= [KNL] Enable kernel profiling via /proc/profile
  1070. Format: [schedule,]<number>
  1071. Param: "schedule" - profile schedule points.
  1072. Param: <number> - step/bucket size as a power of 2 for
  1073. statistical time based profiling.
  1074. Param: "sleep" - profile D-state sleeping (millisecs)
  1075. processor.max_cstate= [HW,ACPI]
  1076. Limit processor to maximum C-state
  1077. max_cstate=9 overrides any DMI blacklist limit.
  1078. processor.nocst [HW,ACPI]
  1079. Ignore the _CST method to determine C-states,
  1080. instead using the legacy FADT method
  1081. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1082. before loading.
  1083. See Documentation/ramdisk.txt.
  1084. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1085. probe for; one of (bare|imps|exps|lifebook|any).
  1086. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1087. per second.
  1088. psmouse.resetafter= [HW,MOUSE]
  1089. Try to reset the device after so many bad packets
  1090. (0 = never).
  1091. psmouse.resolution=
  1092. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1093. psmouse.smartscroll=
  1094. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1095. 0 = disabled, 1 = enabled (default).
  1096. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1097. Format:
  1098. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1099. pt. [PARIDE]
  1100. See Documentation/paride.txt.
  1101. quiet [KNL] Disable most log messages
  1102. r128= [HW,DRM]
  1103. raid= [HW,RAID]
  1104. See Documentation/md.txt.
  1105. ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
  1106. See Documentation/ramdisk.txt.
  1107. ramdisk_blocksize= [RAM]
  1108. See Documentation/ramdisk.txt.
  1109. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1110. New name for the ramdisk parameter.
  1111. See Documentation/ramdisk.txt.
  1112. rcu.blimit= [KNL,BOOT] Set maximum number of finished
  1113. RCU callbacks to process in one batch.
  1114. rcu.qhimark= [KNL,BOOT] Set threshold of queued
  1115. RCU callbacks over which batch limiting is disabled.
  1116. rcu.qlowmark= [KNL,BOOT] Set threshold of queued
  1117. RCU callbacks below which batch limiting is re-enabled.
  1118. rdinit= [KNL]
  1119. Format: <full_path>
  1120. Run specified binary instead of /init from the ramdisk,
  1121. used for early userspace startup. See initrd.
  1122. reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1123. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1124. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1125. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1126. reservetop= [IA-32]
  1127. Format: nn[KMG]
  1128. Reserves a hole at the top of the kernel virtual
  1129. address space.
  1130. reset_devices [KNL] Force drivers to reset the underlying device
  1131. during initialization.
  1132. resume= [SWSUSP]
  1133. Specify the partition device for software suspend
  1134. resume_offset= [SWSUSP]
  1135. Specify the offset from the beginning of the partition
  1136. given by "resume=" at which the swap header is located,
  1137. in <PAGE_SIZE> units (needed only for swap files).
  1138. See Documentation/power/swsusp-and-swap-files.txt
  1139. retain_initrd [RAM] Keep initrd memory after extraction
  1140. rhash_entries= [KNL,NET]
  1141. Set number of hash buckets for route cache
  1142. riscom8= [HW,SERIAL]
  1143. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1144. ro [KNL] Mount root device read-only on boot
  1145. root= [KNL] Root filesystem
  1146. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1147. mount the root filesystem
  1148. rootflags= [KNL] Set root filesystem mount option string
  1149. rootfstype= [KNL] Set root filesystem type
  1150. rw [KNL] Mount root device read-write on boot
  1151. S [KNL] Run init in single mode
  1152. sa1100ir [NET]
  1153. See drivers/net/irda/sa1100_ir.c.
  1154. sb= [HW,OSS]
  1155. Format: <io>,<irq>,<dma>,<dma2>
  1156. sbni= [NET] Granch SBNI12 leased line adapter
  1157. sbpcd= [HW,CD] Soundblaster CD adapter
  1158. Format: <io>,<type>
  1159. See a comment before function sbpcd_setup() in
  1160. drivers/cdrom/sbpcd.c.
  1161. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1162. Format: <io>[,<timeout>[,<isapnp>]]
  1163. scsi_debug_*= [SCSI]
  1164. See drivers/scsi/scsi_debug.c.
  1165. scsi_default_dev_flags=
  1166. [SCSI] SCSI default device flags
  1167. Format: <integer>
  1168. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1169. Format: <vendor>:<model>:<flags>
  1170. (flags are integer value)
  1171. scsi_logging= [SCSI]
  1172. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1173. discovered. async scans them in kernel threads,
  1174. allowing boot to proceed. none ignores them, expecting
  1175. user space to do the scan.
  1176. selinux [SELINUX] Disable or enable SELinux at boot time.
  1177. Format: { "0" | "1" }
  1178. See security/selinux/Kconfig help text.
  1179. 0 -- disable.
  1180. 1 -- enable.
  1181. Default value is set via kernel config option.
  1182. If enabled at boot time, /selinux/disable can be used
  1183. later to disable prior to initial policy load.
  1184. selinux_compat_net =
  1185. [SELINUX] Set initial selinux_compat_net flag value.
  1186. Format: { "0" | "1" }
  1187. 0 -- use new secmark-based packet controls
  1188. 1 -- use legacy packet controls
  1189. Default value is 0 (preferred).
  1190. Value can be changed at runtime via
  1191. /selinux/compat_net.
  1192. serialnumber [BUGS=IA-32]
  1193. sg_def_reserved_size= [SCSI]
  1194. shapers= [NET]
  1195. Maximal number of shapers.
  1196. sim710= [SCSI,HW]
  1197. See header of drivers/scsi/sim710.c.
  1198. simeth= [IA-64]
  1199. simscsi=
  1200. sjcd= [HW,CD]
  1201. Format: <io>,<irq>,<dma>
  1202. See header of drivers/cdrom/sjcd.c.
  1203. slram= [HW,MTD]
  1204. smart2= [HW]
  1205. Format: <io1>[,<io2>[,...,<io8>]]
  1206. snd-ad1816a= [HW,ALSA]
  1207. snd-ad1848= [HW,ALSA]
  1208. snd-ali5451= [HW,ALSA]
  1209. snd-als100= [HW,ALSA]
  1210. snd-als4000= [HW,ALSA]
  1211. snd-azt2320= [HW,ALSA]
  1212. snd-cmi8330= [HW,ALSA]
  1213. snd-cmipci= [HW,ALSA]
  1214. snd-cs4231= [HW,ALSA]
  1215. snd-cs4232= [HW,ALSA]
  1216. snd-cs4236= [HW,ALSA]
  1217. snd-cs4281= [HW,ALSA]
  1218. snd-cs46xx= [HW,ALSA]
  1219. snd-dt019x= [HW,ALSA]
  1220. snd-dummy= [HW,ALSA]
  1221. snd-emu10k1= [HW,ALSA]
  1222. snd-ens1370= [HW,ALSA]
  1223. snd-ens1371= [HW,ALSA]
  1224. snd-es968= [HW,ALSA]
  1225. snd-es1688= [HW,ALSA]
  1226. snd-es18xx= [HW,ALSA]
  1227. snd-es1938= [HW,ALSA]
  1228. snd-es1968= [HW,ALSA]
  1229. snd-fm801= [HW,ALSA]
  1230. snd-gusclassic= [HW,ALSA]
  1231. snd-gusextreme= [HW,ALSA]
  1232. snd-gusmax= [HW,ALSA]
  1233. snd-hdsp= [HW,ALSA]
  1234. snd-ice1712= [HW,ALSA]
  1235. snd-intel8x0= [HW,ALSA]
  1236. snd-interwave= [HW,ALSA]
  1237. snd-interwave-stb=
  1238. [HW,ALSA]
  1239. snd-korg1212= [HW,ALSA]
  1240. snd-maestro3= [HW,ALSA]
  1241. snd-mpu401= [HW,ALSA]
  1242. snd-mtpav= [HW,ALSA]
  1243. snd-nm256= [HW,ALSA]
  1244. snd-opl3sa2= [HW,ALSA]
  1245. snd-opti92x-ad1848=
  1246. [HW,ALSA]
  1247. snd-opti92x-cs4231=
  1248. [HW,ALSA]
  1249. snd-opti93x= [HW,ALSA]
  1250. snd-pmac= [HW,ALSA]
  1251. snd-rme32= [HW,ALSA]
  1252. snd-rme96= [HW,ALSA]
  1253. snd-rme9652= [HW,ALSA]
  1254. snd-sb8= [HW,ALSA]
  1255. snd-sb16= [HW,ALSA]
  1256. snd-sbawe= [HW,ALSA]
  1257. snd-serial= [HW,ALSA]
  1258. snd-sgalaxy= [HW,ALSA]
  1259. snd-sonicvibes= [HW,ALSA]
  1260. snd-sun-amd7930=
  1261. [HW,ALSA]
  1262. snd-sun-cs4231= [HW,ALSA]
  1263. snd-trident= [HW,ALSA]
  1264. snd-usb-audio= [HW,ALSA,USB]
  1265. snd-via82xx= [HW,ALSA]
  1266. snd-virmidi= [HW,ALSA]
  1267. snd-wavefront= [HW,ALSA]
  1268. snd-ymfpci= [HW,ALSA]
  1269. sonycd535= [HW,CD]
  1270. Format: <io>[,<irq>]
  1271. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1272. See Documentation/sonypi.txt
  1273. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1274. See Documentation/specialix.txt.
  1275. spia_io_base= [HW,MTD]
  1276. spia_fio_base=
  1277. spia_pedr=
  1278. spia_peddr=
  1279. sscape= [HW,OSS]
  1280. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1281. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1282. See Documentation/scsi/st.txt.
  1283. st0x= [HW,SCSI]
  1284. See header of drivers/scsi/seagate.c.
  1285. sti= [PARISC,HW]
  1286. Format: <num>
  1287. Set the STI (builtin display/keyboard on the HP-PARISC
  1288. machines) console (graphic card) which should be used
  1289. as the initial boot-console.
  1290. See also comment in drivers/video/console/sticore.c.
  1291. sti_font= [HW]
  1292. See comment in drivers/video/console/sticore.c.
  1293. stifb= [HW]
  1294. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1295. sunrpc.pool_mode=
  1296. [NFS]
  1297. Control how the NFS server code allocates CPUs to
  1298. service thread pools. Depending on how many NICs
  1299. you have and where their interrupts are bound, this
  1300. option will affect which CPUs will do NFS serving.
  1301. Note: this parameter cannot be changed while the
  1302. NFS server is running.
  1303. auto the server chooses an appropriate mode
  1304. automatically using heuristics
  1305. global a single global pool contains all CPUs
  1306. percpu one pool for each CPU
  1307. pernode one pool for each NUMA node (equivalent
  1308. to global on non-NUMA machines)
  1309. swiotlb= [IA-64] Number of I/O TLB slabs
  1310. switches= [HW,M68k]
  1311. sym53c416= [HW,SCSI]
  1312. See header of drivers/scsi/sym53c416.c.
  1313. sysrq_always_enabled
  1314. [KNL]
  1315. Ignore sysrq setting - this boot parameter will
  1316. neutralize any effect of /proc/sys/kernel/sysrq.
  1317. Useful for debugging.
  1318. t128= [HW,SCSI]
  1319. See header of drivers/scsi/t128.c.
  1320. tdfx= [HW,DRM]
  1321. thash_entries= [KNL,NET]
  1322. Set number of hash buckets for TCP connection
  1323. time Show timing data prefixed to each printk message line
  1324. clocksource= [GENERIC_TIME] Override the default clocksource
  1325. Override the default clocksource and use the clocksource
  1326. with the name specified.
  1327. tipar.timeout= [HW,PPT]
  1328. Set communications timeout in tenths of a second
  1329. (default 15).
  1330. tipar.delay= [HW,PPT]
  1331. Set inter-bit delay in microseconds (default 10).
  1332. tmc8xx= [HW,SCSI]
  1333. See header of drivers/scsi/seagate.c.
  1334. tmscsim= [HW,SCSI]
  1335. See comment before function dc390_setup() in
  1336. drivers/scsi/tmscsim.c.
  1337. tp720= [HW,PS2]
  1338. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1339. Format:
  1340. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1341. tsdev.xres= [TS] Horizontal screen resolution.
  1342. tsdev.yres= [TS] Vertical screen resolution.
  1343. turbografx.map[2|3]= [HW,JOY]
  1344. TurboGraFX parallel port interface
  1345. Format:
  1346. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1347. See also Documentation/input/joystick-parport.txt
  1348. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1349. See header of drivers/scsi/u14-34f.c.
  1350. uart401= [HW,OSS]
  1351. Format: <io>,<irq>
  1352. uart6850= [HW,OSS]
  1353. Format: <io>,<irq>
  1354. uhci-hcd.ignore_oc=
  1355. [USB] Ignore overcurrent events (default N).
  1356. Some badly-designed motherboards generate lots of
  1357. bogus events, for ports that aren't wired to
  1358. anything. Set this parameter to avoid log spamming.
  1359. Note that genuine overcurrent events won't be
  1360. reported either.
  1361. usbcore.autosuspend=
  1362. [USB] The autosuspend time delay (in seconds) used
  1363. for newly-detected USB devices (default 2). This
  1364. is the time required before an idle device will be
  1365. autosuspended. Devices for which the delay is set
  1366. to a negative value won't be autosuspended at all.
  1367. usbhid.mousepoll=
  1368. [USBHID] The interval which mice are to be polled at.
  1369. vdso= [IA-32,SH]
  1370. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  1371. vdso=1: enable VDSO (default)
  1372. vdso=0: disable VDSO mapping
  1373. video= [FB] Frame buffer configuration
  1374. See Documentation/fb/modedb.txt.
  1375. vga= [BOOT,IA-32] Select a particular video mode
  1376. See Documentation/i386/boot.txt and
  1377. Documentation/svga.txt.
  1378. Use vga=ask for menu.
  1379. This is actually a boot loader parameter; the value is
  1380. passed to the kernel using a special protocol.
  1381. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1382. size of <nn>. This can be used to increase the
  1383. minimum size (128MB on x86). It can also be used to
  1384. decrease the size and leave more room for directly
  1385. mapped kernel RAM.
  1386. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1387. Format: <command>
  1388. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1389. Format: <command>
  1390. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1391. Format: <command>
  1392. waveartist= [HW,OSS]
  1393. Format: <io>,<irq>,<dma>,<dma2>
  1394. wd33c93= [HW,SCSI]
  1395. See header of drivers/scsi/wd33c93.c.
  1396. wd7000= [HW,SCSI]
  1397. See header of drivers/scsi/wd7000.c.
  1398. wdt= [WDT] Watchdog
  1399. See Documentation/watchdog/watchdog.txt.
  1400. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1401. xd_geo= See header of drivers/block/xd.c.
  1402. xirc2ps_cs= [NET,PCMCIA]
  1403. Format:
  1404. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1405. norandmaps Don't use address space randomization
  1406. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
  1407. unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
  1408. This is useful to get more information why
  1409. you got a "dwarf2 unwinder stuck"
  1410. ______________________________________________________________________
  1411. TODO:
  1412. Add documentation for ALSA options.
  1413. Add more DRM drivers.