kernel-parameters.txt 77 KB

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  1. Kernel Parameters
  2. ~~~~~~~~~~~~~~~~~
  3. The following is a consolidated list of the kernel parameters as implemented
  4. (mostly) by the __setup() macro and sorted into English Dictionary order
  5. (defined as ignoring all punctuation and sorting digits before letters in a
  6. case insensitive manner), and with descriptions where known.
  7. Module parameters for loadable modules are specified only as the
  8. parameter name with optional '=' and value as appropriate, such as:
  9. modprobe usbcore blinkenlights=1
  10. Module parameters for modules that are built into the kernel image
  11. are specified on the kernel command line with the module name plus
  12. '.' plus parameter name, with '=' and value if appropriate, such as:
  13. usbcore.blinkenlights=1
  14. This document may not be entirely up to date and comprehensive. The command
  15. "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
  16. module. Loadable modules, after being loaded into the running kernel, also
  17. reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
  18. parameters may be changed at runtime by the command
  19. "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
  20. The parameters listed below are only valid if certain kernel build options were
  21. enabled and if respective hardware is present. The text in square brackets at
  22. the beginning of each description states the restrictions within which a
  23. parameter is applicable:
  24. ACPI ACPI support is enabled.
  25. AGP AGP (Accelerated Graphics Port) is enabled.
  26. ALSA ALSA sound support is enabled.
  27. APIC APIC support is enabled.
  28. APM Advanced Power Management support is enabled.
  29. AVR32 AVR32 architecture is enabled.
  30. AX25 Appropriate AX.25 support is enabled.
  31. BLACKFIN Blackfin architecture is enabled.
  32. DRM Direct Rendering Management support is enabled.
  33. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
  34. EFI EFI Partitioning (GPT) is enabled
  35. EIDE EIDE/ATAPI support is enabled.
  36. FB The frame buffer device is enabled.
  37. HW Appropriate hardware is enabled.
  38. IA-64 IA-64 architecture is enabled.
  39. IOSCHED More than one I/O scheduler is enabled.
  40. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  41. ISAPNP ISA PnP code is enabled.
  42. ISDN Appropriate ISDN support is enabled.
  43. JOY Appropriate joystick support is enabled.
  44. LIBATA Libata driver is enabled
  45. LP Printer support is enabled.
  46. LOOP Loopback device support is enabled.
  47. M68k M68k architecture is enabled.
  48. These options have more detailed description inside of
  49. Documentation/m68k/kernel-options.txt.
  50. MCA MCA bus support is enabled.
  51. MDA MDA console support is enabled.
  52. MOUSE Appropriate mouse support is enabled.
  53. MSI Message Signaled Interrupts (PCI).
  54. MTD MTD (Memory Technology Device) support is enabled.
  55. NET Appropriate network support is enabled.
  56. NUMA NUMA support is enabled.
  57. GENERIC_TIME The generic timeofday code is enabled.
  58. NFS Appropriate NFS support is enabled.
  59. OSS OSS sound support is enabled.
  60. PV_OPS A paravirtualized kernel is enabled.
  61. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  62. PARISC The PA-RISC architecture is enabled.
  63. PCI PCI bus support is enabled.
  64. PCIE PCI Express support is enabled.
  65. PCMCIA The PCMCIA subsystem is enabled.
  66. PNP Plug & Play support is enabled.
  67. PPC PowerPC architecture is enabled.
  68. PPT Parallel port support is enabled.
  69. PS2 Appropriate PS/2 support is enabled.
  70. RAM RAM disk support is enabled.
  71. ROOTPLUG The example Root Plug LSM is enabled.
  72. S390 S390 architecture is enabled.
  73. SCSI Appropriate SCSI support is enabled.
  74. A lot of drivers has their options described inside of
  75. Documentation/scsi/.
  76. SECURITY Different security models are enabled.
  77. SELINUX SELinux support is enabled.
  78. SERIAL Serial support is enabled.
  79. SH SuperH architecture is enabled.
  80. SMP The kernel is an SMP kernel.
  81. SPARC Sparc architecture is enabled.
  82. SWSUSP Software suspend (hibernation) is enabled.
  83. SUSPEND System suspend states are enabled.
  84. FTRACE Function tracing enabled.
  85. TS Appropriate touchscreen support is enabled.
  86. USB USB support is enabled.
  87. USBHID USB Human Interface Device support is enabled.
  88. V4L Video For Linux support is enabled.
  89. VGA The VGA console has been enabled.
  90. VT Virtual terminal support is enabled.
  91. WDT Watchdog support is enabled.
  92. XT IBM PC/XT MFM hard disk support is enabled.
  93. X86-32 X86-32, aka i386 architecture is enabled.
  94. X86-64 X86-64 architecture is enabled.
  95. More X86-64 boot options can be found in
  96. Documentation/x86/x86_64/boot-options.txt .
  97. X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
  98. In addition, the following text indicates that the option:
  99. BUGS= Relates to possible processor bugs on the said processor.
  100. KNL Is a kernel start-up parameter.
  101. BOOT Is a boot loader parameter.
  102. Parameters denoted with BOOT are actually interpreted by the boot
  103. loader, and have no meaning to the kernel directly.
  104. Do not modify the syntax of boot loader parameters without extreme
  105. need or coordination with <Documentation/x86/i386/boot.txt>.
  106. There are also arch-specific kernel-parameters not documented here.
  107. See for example <Documentation/x86/x86_64/boot-options.txt>.
  108. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  109. a trailing = on the name of any parameter states that that parameter will
  110. be entered as an environment variable, whereas its absence indicates that
  111. it will appear as a kernel argument readable via /proc/cmdline by programs
  112. running once the system is up.
  113. The number of kernel parameters is not limited, but the length of the
  114. complete command line (parameters including spaces etc.) is limited to
  115. a fixed number of characters. This limit depends on the architecture
  116. and is between 256 and 4096 characters. It is defined in the file
  117. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  118. acpi= [HW,ACPI,X86-64,i386]
  119. Advanced Configuration and Power Interface
  120. Format: { force | off | ht | strict | noirq }
  121. force -- enable ACPI if default was off
  122. off -- disable ACPI if default was on
  123. noirq -- do not use ACPI for IRQ routing
  124. ht -- run only enough ACPI to enable Hyper Threading
  125. strict -- Be less tolerant of platforms that are not
  126. strictly ACPI specification compliant.
  127. See also Documentation/power/pm.txt, pci=noacpi
  128. acpi_apic_instance= [ACPI, IOAPIC]
  129. Format: <int>
  130. 2: use 2nd APIC table, if available
  131. 1,0: use 1st APIC table
  132. default: 0
  133. acpi_sleep= [HW,ACPI] Sleep options
  134. Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
  135. See Documentation/power/video.txt for s3_bios and s3_mode.
  136. s3_beep is for debugging; it makes the PC's speaker beep
  137. as soon as the kernel's real-mode entry point is called.
  138. s4_nohwsig prevents ACPI hardware signature from being
  139. used during resume from hibernation.
  140. old_ordering causes the ACPI 1.0 ordering of the _PTS
  141. control method, wrt putting devices into low power
  142. states, to be enforced (the ACPI 2.0 ordering of _PTS is
  143. used by default).
  144. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  145. Format: { level | edge | high | low }
  146. acpi_irq_balance [HW,ACPI]
  147. ACPI will balance active IRQs
  148. default in APIC mode
  149. acpi_irq_nobalance [HW,ACPI]
  150. ACPI will not move active IRQs (default)
  151. default in PIC mode
  152. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  153. use by PCI
  154. Format: <irq>,<irq>...
  155. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  156. Format: <irq>,<irq>...
  157. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  158. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  159. Format: To spoof as Windows 98: ="Microsoft Windows"
  160. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  161. acpi_osi="string1" # add string1 -- only one string
  162. acpi_osi="!string2" # remove built-in string2
  163. acpi_osi= # disable all strings
  164. acpi_serialize [HW,ACPI] force serialization of AML methods
  165. acpi_skip_timer_override [HW,ACPI]
  166. Recognize and ignore IRQ0/pin2 Interrupt Override.
  167. For broken nForce2 BIOS resulting in XT-PIC timer.
  168. acpi_use_timer_override [HW,ACPI}
  169. Use timer override. For some broken Nvidia NF5 boards
  170. that require a timer override, but don't have
  171. HPET
  172. acpi_backlight= [HW,ACPI]
  173. acpi_backlight=vendor
  174. acpi_backlight=video
  175. If set to vendor, prefer vendor specific driver
  176. (e.g. thinkpad_acpi, sony_acpi, etc.) instead
  177. of the ACPI video.ko driver.
  178. acpi_display_output= [HW,ACPI]
  179. acpi_display_output=vendor
  180. acpi_display_output=video
  181. See above.
  182. acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
  183. acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
  184. Format: <int>
  185. CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
  186. debug output. Bits in debug_layer correspond to a
  187. _COMPONENT in an ACPI source file, e.g.,
  188. #define _COMPONENT ACPI_PCI_COMPONENT
  189. Bits in debug_level correspond to a level in
  190. ACPI_DEBUG_PRINT statements, e.g.,
  191. ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
  192. The debug_level mask defaults to "info". See
  193. Documentation/acpi/debug.txt for more information about
  194. debug layers and levels.
  195. Enable processor driver info messages:
  196. acpi.debug_layer=0x20000000
  197. Enable PCI/PCI interrupt routing info messages:
  198. acpi.debug_layer=0x400000
  199. Enable AML "Debug" output, i.e., stores to the Debug
  200. object while interpreting AML:
  201. acpi.debug_layer=0xffffffff acpi.debug_level=0x2
  202. Enable all messages related to ACPI hardware:
  203. acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
  204. Some values produce so much output that the system is
  205. unusable. The "log_buf_len" parameter may be useful
  206. if you need to capture more output.
  207. acpi.power_nocheck= [HW,ACPI]
  208. Format: 1/0 enable/disable the check of power state.
  209. On some bogus BIOS the _PSC object/_STA object of
  210. power resource can't return the correct device power
  211. state. In such case it is unneccessary to check its
  212. power state again in power transition.
  213. 1 : disable the power state check
  214. acpi_pm_good [X86-32,X86-64]
  215. Override the pmtimer bug detection: force the kernel
  216. to assume that this machine's pmtimer latches its value
  217. and always returns good values.
  218. agp= [AGP]
  219. { off | try_unsupported }
  220. off: disable AGP support
  221. try_unsupported: try to drive unsupported chipsets
  222. (may crash computer or cause data corruption)
  223. enable_timer_pin_1 [i386,x86-64]
  224. Enable PIN 1 of APIC timer
  225. Can be useful to work around chipset bugs
  226. (in particular on some ATI chipsets).
  227. The kernel tries to set a reasonable default.
  228. disable_timer_pin_1 [i386,x86-64]
  229. Disable PIN 1 of APIC timer
  230. Can be useful to work around chipset bugs.
  231. ad1848= [HW,OSS]
  232. Format: <io>,<irq>,<dma>,<dma2>,<type>
  233. advansys= [HW,SCSI]
  234. See header of drivers/scsi/advansys.c.
  235. advwdt= [HW,WDT] Advantech WDT
  236. Format: <iostart>,<iostop>
  237. aedsp16= [HW,OSS] Audio Excel DSP 16
  238. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  239. See also header of sound/oss/aedsp16.c.
  240. aha152x= [HW,SCSI]
  241. See Documentation/scsi/aha152x.txt.
  242. aha1542= [HW,SCSI]
  243. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  244. aic7xxx= [HW,SCSI]
  245. See Documentation/scsi/aic7xxx.txt.
  246. aic79xx= [HW,SCSI]
  247. See Documentation/scsi/aic79xx.txt.
  248. amd_iommu= [HW,X86-84]
  249. Pass parameters to the AMD IOMMU driver in the system.
  250. Possible values are:
  251. isolate - enable device isolation (each device, as far
  252. as possible, will get its own protection
  253. domain) [default]
  254. share - put every device behind one IOMMU into the
  255. same protection domain
  256. fullflush - enable flushing of IO/TLB entries when
  257. they are unmapped. Otherwise they are
  258. flushed before they will be reused, which
  259. is a lot of faster
  260. amd_iommu_size= [HW,X86-64]
  261. Define the size of the aperture for the AMD IOMMU
  262. driver. Possible values are:
  263. '32M', '64M' (default), '128M', '256M', '512M', '1G'
  264. amijoy.map= [HW,JOY] Amiga joystick support
  265. Map of devices attached to JOY0DAT and JOY1DAT
  266. Format: <a>,<b>
  267. See also Documentation/kernel/input/joystick.txt
  268. analog.map= [HW,JOY] Analog joystick and gamepad support
  269. Specifies type or capabilities of an analog joystick
  270. connected to one of 16 gameports
  271. Format: <type1>,<type2>,..<type16>
  272. apc= [HW,SPARC]
  273. Power management functions (SPARCstation-4/5 + deriv.)
  274. Format: noidle
  275. Disable APC CPU standby support. SPARCstation-Fox does
  276. not play well with APC CPU idle - disable it if you have
  277. APC and your system crashes randomly.
  278. apic= [APIC,i386] Advanced Programmable Interrupt Controller
  279. Change the output verbosity whilst booting
  280. Format: { quiet (default) | verbose | debug }
  281. Change the amount of debugging information output
  282. when initialising the APIC and IO-APIC components.
  283. apm= [APM] Advanced Power Management
  284. See header of arch/x86/kernel/apm_32.c.
  285. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  286. Format: <io>,<irq>,<nodeID>
  287. ataflop= [HW,M68k]
  288. atarimouse= [HW,MOUSE] Atari Mouse
  289. atascsi= [HW,SCSI] Atari SCSI
  290. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  291. EzKey and similar keyboards
  292. atkbd.reset= [HW] Reset keyboard during initialization
  293. atkbd.set= [HW] Select keyboard code set
  294. Format: <int> (2 = AT (default), 3 = PS/2)
  295. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  296. keyboards
  297. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  298. Format: <bool> (0 = real, 1 = synthetic (default))
  299. atkbd.softrepeat= [HW]
  300. Use software keyboard repeat
  301. autotest [IA64]
  302. baycom_epp= [HW,AX25]
  303. Format: <io>,<mode>
  304. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  305. Format: <io>,<mode>
  306. See header of drivers/net/hamradio/baycom_par.c.
  307. baycom_ser_fdx= [HW,AX25]
  308. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  309. Format: <io>,<irq>,<mode>[,<baud>]
  310. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  311. baycom_ser_hdx= [HW,AX25]
  312. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  313. Format: <io>,<irq>,<mode>
  314. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  315. boot_delay= Milliseconds to delay each printk during boot.
  316. Values larger than 10 seconds (10000) are changed to
  317. no delay (0).
  318. Format: integer
  319. bootmem_debug [KNL] Enable bootmem allocator debug messages.
  320. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  321. bttv.radio= Most important insmod options are available as
  322. kernel args too.
  323. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  324. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  325. BusLogic= [HW,SCSI]
  326. See drivers/scsi/BusLogic.c, comment before function
  327. BusLogic_ParseDriverOptions().
  328. c101= [NET] Moxa C101 synchronous serial card
  329. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  330. Sometimes CPU hardware bugs make them report the cache
  331. size incorrectly. The kernel will attempt work arounds
  332. to fix known problems, but for some CPUs it is not
  333. possible to determine what the correct size should be.
  334. This option provides an override for these situations.
  335. security= [SECURITY] Choose a security module to enable at boot.
  336. If this boot parameter is not specified, only the first
  337. security module asking for security registration will be
  338. loaded. An invalid security module name will be treated
  339. as if no module has been chosen.
  340. capability.disable=
  341. [SECURITY] Disable capabilities. This would normally
  342. be used only if an alternative security model is to be
  343. configured. Potentially dangerous and should only be
  344. used if you are entirely sure of the consequences.
  345. ccw_timeout_log [S390]
  346. See Documentation/s390/CommonIO for details.
  347. cgroup_disable= [KNL] Disable a particular controller
  348. Format: {name of the controller(s) to disable}
  349. {Currently supported controllers - "memory"}
  350. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  351. Format: { "0" | "1" }
  352. See security/selinux/Kconfig help text.
  353. 0 -- check protection applied by kernel (includes
  354. any implied execute protection).
  355. 1 -- check protection requested by application.
  356. Default value is set via a kernel config option.
  357. Value can be changed at runtime via
  358. /selinux/checkreqprot.
  359. cio_ignore= [S390]
  360. See Documentation/s390/CommonIO for details.
  361. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  362. [Deprecated]
  363. Forces specified clocksource (if available) to be used
  364. when calculating gettimeofday(). If specified
  365. clocksource is not available, it defaults to PIT.
  366. Format: { pit | tsc | cyclone | pmtmr }
  367. clocksource= [GENERIC_TIME] Override the default clocksource
  368. Format: <string>
  369. Override the default clocksource and use the clocksource
  370. with the name specified.
  371. Some clocksource names to choose from, depending on
  372. the platform:
  373. [all] jiffies (this is the base, fallback clocksource)
  374. [ACPI] acpi_pm
  375. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  376. pxa_timer,timer3,32k_counter,timer0_1
  377. [AVR32] avr32
  378. [X86-32] pit,hpet,tsc,vmi-timer;
  379. scx200_hrt on Geode; cyclone on IBM x440
  380. [MIPS] MIPS
  381. [PARISC] cr16
  382. [S390] tod
  383. [SH] SuperH
  384. [SPARC64] tick
  385. [X86-64] hpet,tsc
  386. clearcpuid=BITNUM [X86]
  387. Disable CPUID feature X for the kernel. See
  388. include/asm-x86/cpufeature.h for the valid bit numbers.
  389. Note the Linux specific bits are not necessarily
  390. stable over kernel options, but the vendor specific
  391. ones should be.
  392. Also note that user programs calling CPUID directly
  393. or using the feature without checking anything
  394. will still see it. This just prevents it from
  395. being used by the kernel or shown in /proc/cpuinfo.
  396. Also note the kernel might malfunction if you disable
  397. some critical bits.
  398. code_bytes [IA32/X86_64] How many bytes of object code to print
  399. in an oops report.
  400. Range: 0 - 8192
  401. Default: 64
  402. hpet= [X86-32,HPET] option to control HPET usage
  403. Format: { enable (default) | disable | force }
  404. disable: disable HPET and use PIT instead
  405. force: allow force enabled of undocumented chips (ICH4,
  406. VIA, nVidia)
  407. com20020= [HW,NET] ARCnet - COM20020 chipset
  408. Format:
  409. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  410. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  411. Format: <io>[,<irq>]
  412. com90xx= [HW,NET]
  413. ARCnet - COM90xx chipset (memory-mapped buffers)
  414. Format: <io>[,<irq>[,<memstart>]]
  415. condev= [HW,S390] console device
  416. conmode=
  417. console= [KNL] Output console device and options.
  418. tty<n> Use the virtual console device <n>.
  419. ttyS<n>[,options]
  420. ttyUSB0[,options]
  421. Use the specified serial port. The options are of
  422. the form "bbbbpnf", where "bbbb" is the baud rate,
  423. "p" is parity ("n", "o", or "e"), "n" is number of
  424. bits, and "f" is flow control ("r" for RTS or
  425. omit it). Default is "9600n8".
  426. See Documentation/serial-console.txt for more
  427. information. See
  428. Documentation/networking/netconsole.txt for an
  429. alternative.
  430. uart[8250],io,<addr>[,options]
  431. uart[8250],mmio,<addr>[,options]
  432. Start an early, polled-mode console on the 8250/16550
  433. UART at the specified I/O port or MMIO address,
  434. switching to the matching ttyS device later. The
  435. options are the same as for ttyS, above.
  436. If the device connected to the port is not a TTY but a braille
  437. device, prepend "brl," before the device type, for instance
  438. console=brl,ttyS0
  439. For now, only VisioBraille is supported.
  440. earlycon= [KNL] Output early console device and options.
  441. uart[8250],io,<addr>[,options]
  442. uart[8250],mmio,<addr>[,options]
  443. Start an early, polled-mode console on the 8250/16550
  444. UART at the specified I/O port or MMIO address.
  445. The options are the same as for ttyS, above.
  446. no_console_suspend
  447. [HW] Never suspend the console
  448. Disable suspending of consoles during suspend and
  449. hibernate operations. Once disabled, debugging
  450. messages can reach various consoles while the rest
  451. of the system is being put to sleep (ie, while
  452. debugging driver suspend/resume hooks). This may
  453. not work reliably with all consoles, but is known
  454. to work with serial and VGA consoles.
  455. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  456. Format:
  457. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  458. crashkernel=nn[KMG]@ss[KMG]
  459. [KNL] Reserve a chunk of physical memory to
  460. hold a kernel to switch to with kexec on panic.
  461. crashkernel=range1:size1[,range2:size2,...][@offset]
  462. [KNL] Same as above, but depends on the memory
  463. in the running system. The syntax of range is
  464. start-[end] where start and end are both
  465. a memory unit (amount[KMG]). See also
  466. Documentation/kdump/kdump.txt for a example.
  467. cs4232= [HW,OSS]
  468. Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
  469. cs89x0_dma= [HW,NET]
  470. Format: <dma>
  471. cs89x0_media= [HW,NET]
  472. Format: { rj45 | aui | bnc }
  473. dasd= [HW,NET]
  474. See header of drivers/s390/block/dasd_devmap.c.
  475. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  476. (one device per port)
  477. Format: <port#>,<type>
  478. See also Documentation/input/joystick-parport.txt
  479. debug [KNL] Enable kernel debugging (events log level).
  480. debug_locks_verbose=
  481. [KNL] verbose self-tests
  482. Format=<0|1>
  483. Print debugging info while doing the locking API
  484. self-tests.
  485. We default to 0 (no extra messages), setting it to
  486. 1 will print _a lot_ more information - normally
  487. only useful to kernel developers.
  488. debug_objects [KNL] Enable object debugging
  489. debugpat [X86] Enable PAT debugging
  490. decnet.addr= [HW,NET]
  491. Format: <area>[,<node>]
  492. See also Documentation/networking/decnet.txt.
  493. vt.default_blu= [VT]
  494. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  495. Change the default blue palette of the console.
  496. This is a 16-member array composed of values
  497. ranging from 0-255.
  498. vt.default_grn= [VT]
  499. Format: <green0>,<green1>,<green2>,...,<green15>
  500. Change the default green palette of the console.
  501. This is a 16-member array composed of values
  502. ranging from 0-255.
  503. vt.default_red= [VT]
  504. Format: <red0>,<red1>,<red2>,...,<red15>
  505. Change the default red palette of the console.
  506. This is a 16-member array composed of values
  507. ranging from 0-255.
  508. vt.default_utf8=
  509. [VT]
  510. Format=<0|1>
  511. Set system-wide default UTF-8 mode for all tty's.
  512. Default is 1, i.e. UTF-8 mode is enabled for all
  513. newly opened terminals.
  514. dhash_entries= [KNL]
  515. Set number of hash buckets for dentry cache.
  516. digi= [HW,SERIAL]
  517. IO parameters + enable/disable command.
  518. digiepca= [HW,SERIAL]
  519. See drivers/char/README.epca and
  520. Documentation/serial/digiepca.txt.
  521. disable_mtrr_cleanup [X86]
  522. enable_mtrr_cleanup [X86]
  523. The kernel tries to adjust MTRR layout from continuous
  524. to discrete, to make X server driver able to add WB
  525. entry later. This parameter enables/disables that.
  526. mtrr_chunk_size=nn[KMG] [X86]
  527. used for mtrr cleanup. It is largest continous chunk
  528. that could hold holes aka. UC entries.
  529. mtrr_gran_size=nn[KMG] [X86]
  530. Used for mtrr cleanup. It is granularity of mtrr block.
  531. Default is 1.
  532. Large value could prevent small alignment from
  533. using up MTRRs.
  534. mtrr_spare_reg_nr=n [X86]
  535. Format: <integer>
  536. Range: 0,7 : spare reg number
  537. Default : 1
  538. Used for mtrr cleanup. It is spare mtrr entries number.
  539. Set to 2 or more if your graphical card needs more.
  540. disable_mtrr_trim [X86, Intel and AMD only]
  541. By default the kernel will trim any uncacheable
  542. memory out of your available memory pool based on
  543. MTRR settings. This parameter disables that behavior,
  544. possibly causing your machine to run very slowly.
  545. dmasound= [HW,OSS] Sound subsystem buffers
  546. dscc4.setup= [NET]
  547. dtc3181e= [HW,SCSI]
  548. earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
  549. earlyprintk=vga
  550. earlyprintk=serial[,ttySn[,baudrate]]
  551. earlyprintk=dbgp
  552. Append ",keep" to not disable it when the real console
  553. takes over.
  554. Only vga or serial or usb debug port at a time.
  555. Currently only ttyS0 and ttyS1 are supported.
  556. Interaction with the standard serial driver is not
  557. very good.
  558. The VGA output is eventually overwritten by the real
  559. console.
  560. eata= [HW,SCSI]
  561. edd= [EDD]
  562. Format: {"off" | "on" | "skip[mbr]"}
  563. eisa_irq_edge= [PARISC,HW]
  564. See header of drivers/parisc/eisa.c.
  565. elanfreq= [X86-32]
  566. See comment before function elanfreq_setup() in
  567. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
  568. elevator= [IOSCHED]
  569. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  570. See Documentation/block/as-iosched.txt and
  571. Documentation/block/deadline-iosched.txt for details.
  572. elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
  573. Specifies physical address of start of kernel core
  574. image elf header. Generally kexec loader will
  575. pass this option to capture kernel.
  576. See Documentation/kdump/kdump.txt for details.
  577. enforcing [SELINUX] Set initial enforcing status.
  578. Format: {"0" | "1"}
  579. See security/selinux/Kconfig help text.
  580. 0 -- permissive (log only, no denials).
  581. 1 -- enforcing (deny and log).
  582. Default value is 0.
  583. Value can be changed at runtime via /selinux/enforce.
  584. es1371= [HW,OSS]
  585. Format: <spdif>,[<nomix>,[<amplifier>]]
  586. See also header of sound/oss/es1371.c.
  587. ether= [HW,NET] Ethernet cards parameters
  588. This option is obsoleted by the "netdev=" option, which
  589. has equivalent usage. See its documentation for details.
  590. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  591. Format: <io>[,<irq>]
  592. failslab=
  593. fail_page_alloc=
  594. fail_make_request=[KNL]
  595. General fault injection mechanism.
  596. Format: <interval>,<probability>,<space>,<times>
  597. See also /Documentation/fault-injection/.
  598. fd_mcs= [HW,SCSI]
  599. See header of drivers/scsi/fd_mcs.c.
  600. fdomain= [HW,SCSI]
  601. See header of drivers/scsi/fdomain.c.
  602. floppy= [HW]
  603. See Documentation/blockdev/floppy.txt.
  604. force_pal_cache_flush
  605. [IA-64] Avoid check_sal_cache_flush which may hang on
  606. buggy SAL_CACHE_FLUSH implementations. Using this
  607. parameter will force ia64_sal_cache_flush to call
  608. ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
  609. ftrace=[tracer]
  610. [ftrace] will set and start the specified tracer
  611. as early as possible in order to facilitate early
  612. boot debugging.
  613. ftrace_dump_on_oops
  614. [ftrace] will dump the trace buffers on oops.
  615. gamecon.map[2|3]=
  616. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  617. support via parallel port (up to 5 devices per port)
  618. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  619. See also Documentation/input/joystick-parport.txt
  620. gamma= [HW,DRM]
  621. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  622. Format: off | on
  623. default: on
  624. gdth= [HW,SCSI]
  625. See header of drivers/scsi/gdth.c.
  626. gpt [EFI] Forces disk with valid GPT signature but
  627. invalid Protective MBR to be treated as GPT.
  628. gvp11= [HW,SCSI]
  629. hashdist= [KNL,NUMA] Large hashes allocated during boot
  630. are distributed across NUMA nodes. Defaults on
  631. for IA-64, off otherwise.
  632. Format: 0 | 1 (for off | on)
  633. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  634. hd= [EIDE] (E)IDE hard drive subsystem geometry
  635. Format: <cyl>,<head>,<sect>
  636. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  637. size of <nn>. This works even on boxes that have no
  638. highmem otherwise. This also works to reduce highmem
  639. size on bigger boxes.
  640. highres= [KNL] Enable/disable high resolution timer mode.
  641. Valid parameters: "on", "off"
  642. Default: "on"
  643. hisax= [HW,ISDN]
  644. See Documentation/isdn/README.HiSax.
  645. hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
  646. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
  647. On x86-64 and powerpc, this option can be specified
  648. multiple times interleaved with hugepages= to reserve
  649. huge pages of different sizes. Valid pages sizes on
  650. x86-64 are 2M (when the CPU supports "pse") and 1G
  651. (when the CPU supports the "pdpe1gb" cpuinfo flag)
  652. Note that 1GB pages can only be allocated at boot time
  653. using hugepages= and not freed afterwards.
  654. default_hugepagesz=
  655. [same as hugepagesz=] The size of the default
  656. HugeTLB page size. This is the size represented by
  657. the legacy /proc/ hugepages APIs, used for SHM, and
  658. default size when mounting hugetlbfs filesystems.
  659. Defaults to the default architecture's huge page size
  660. if not specified.
  661. hlt [BUGS=ARM,SH]
  662. hvc_iucv= [S390] Number of z/VM IUCV Hypervisor console (HVC)
  663. back-ends. Valid parameters: 0..8
  664. i8042.debug [HW] Toggle i8042 debug mode
  665. i8042.direct [HW] Put keyboard port into non-translated mode
  666. i8042.dumbkbd [HW] Pretend that controller can only read data from
  667. keyboard and cannot control its state
  668. (Don't attempt to blink the leds)
  669. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  670. i8042.nokbd [HW] Don't check/create keyboard port
  671. i8042.noloop [HW] Disable the AUX Loopback command while probing
  672. for the AUX port
  673. i8042.nomux [HW] Don't check presence of an active multiplexing
  674. controller
  675. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  676. controllers
  677. i8042.panicblink=
  678. [HW] Frequency with which keyboard LEDs should blink
  679. when kernel panics (default is 0.5 sec)
  680. i8042.reset [HW] Reset the controller during init and cleanup
  681. i8042.unlock [HW] Unlock (ignore) the keylock
  682. i810= [HW,DRM]
  683. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  684. indicates that the driver is running on unsupported
  685. hardware.
  686. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  687. does not match list of supported models.
  688. i8k.power_status
  689. [HW] Report power status in /proc/i8k
  690. (disabled by default)
  691. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  692. capability is set.
  693. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  694. See Documentation/mca.txt.
  695. icn= [HW,ISDN]
  696. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  697. ide= [HW] (E)IDE subsystem
  698. Format: ide=nodma or ide=doubler
  699. See Documentation/ide/ide.txt.
  700. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  701. See Documentation/ide/ide.txt.
  702. idle= [X86]
  703. Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
  704. Poll forces a polling idle loop that can slightly improves the performance
  705. of waking up a idle CPU, but will use a lot of power and make the system
  706. run hot. Not recommended.
  707. idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
  708. to not use it because it doesn't save as much power as a normal idle
  709. loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
  710. as idle=poll.
  711. idle=halt. Halt is forced to be used for CPU idle.
  712. In such case C2/C3 won't be used again.
  713. idle=nomwait. Disable mwait for CPU C-states
  714. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  715. Claim all unknown PCI IDE storage controllers.
  716. ignore_loglevel [KNL]
  717. Ignore loglevel setting - this will print /all/
  718. kernel messages to the console. Useful for debugging.
  719. ihash_entries= [KNL]
  720. Set number of hash buckets for inode cache.
  721. in2000= [HW,SCSI]
  722. See header of drivers/scsi/in2000.c.
  723. init= [KNL]
  724. Format: <full_path>
  725. Run specified binary instead of /sbin/init as init
  726. process.
  727. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  728. for working out where the kernel is dying during
  729. startup.
  730. initrd= [BOOT] Specify the location of the initial ramdisk
  731. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  732. Format: <irq>
  733. inttest= [IA64]
  734. iommu= [x86]
  735. off
  736. force
  737. noforce
  738. biomerge
  739. panic
  740. nopanic
  741. merge
  742. nomerge
  743. forcesac
  744. soft
  745. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  746. off
  747. Disable intel iommu driver.
  748. igfx_off [Default Off]
  749. By default, gfx is mapped as normal device. If a gfx
  750. device has a dedicated DMAR unit, the DMAR unit is
  751. bypassed by not enabling DMAR with this option. In
  752. this case, gfx device will use physical address for
  753. DMA.
  754. forcedac [x86_64]
  755. With this option iommu will not optimize to look
  756. for io virtual address below 32 bit forcing dual
  757. address cycle on pci bus for cards supporting greater
  758. than 32 bit addressing. The default is to look
  759. for translation below 32 bit and if not available
  760. then look in the higher range.
  761. strict [Default Off]
  762. With this option on every unmap_single operation will
  763. result in a hardware IOTLB flush operation as opposed
  764. to batching them for performance.
  765. io_delay= [X86-32,X86-64] I/O delay method
  766. 0x80
  767. Standard port 0x80 based delay
  768. 0xed
  769. Alternate port 0xed based delay (needed on some systems)
  770. udelay
  771. Simple two microseconds delay
  772. none
  773. No delay
  774. io7= [HW] IO7 for Marvel based alpha systems
  775. See comment before marvel_specify_io7 in
  776. arch/alpha/kernel/core_marvel.c.
  777. ip= [IP_PNP]
  778. See Documentation/filesystems/nfsroot.txt.
  779. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  780. See comment before ip2_setup() in
  781. drivers/char/ip2/ip2base.c.
  782. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  783. See header of drivers/scsi/ips.c.
  784. ports= [IP_VS_FTP] IPVS ftp helper module
  785. Default is 21.
  786. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  787. may be specified.
  788. Format: <port>,<port>....
  789. irqfixup [HW]
  790. When an interrupt is not handled search all handlers
  791. for it. Intended to get systems with badly broken
  792. firmware running.
  793. irqpoll [HW]
  794. When an interrupt is not handled search all handlers
  795. for it. Also check all handlers each timer
  796. interrupt. Intended to get systems with badly broken
  797. firmware running.
  798. isapnp= [ISAPNP]
  799. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  800. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  801. Format:
  802. <cpu number>,...,<cpu number>
  803. or
  804. <cpu number>-<cpu number>
  805. (must be a positive range in ascending order)
  806. or a mixture
  807. <cpu number>,...,<cpu number>-<cpu number>
  808. This option can be used to specify one or more CPUs
  809. to isolate from the general SMP balancing and scheduling
  810. algorithms. You can move a process onto or off an
  811. "isolated" CPU via the CPU affinity syscalls or cpuset.
  812. <cpu number> begins at 0 and the maximum value is
  813. "number of CPUs in system - 1".
  814. This option is the preferred way to isolate CPUs. The
  815. alternative -- manually setting the CPU mask of all
  816. tasks in the system -- can cause problems and
  817. suboptimal load balancer performance.
  818. iucv= [HW,NET]
  819. js= [HW,JOY] Analog joystick
  820. See Documentation/input/joystick.txt.
  821. kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  822. specifies the amount of memory usable by the kernel
  823. for non-movable allocations. The requested amount is
  824. spread evenly throughout all nodes in the system. The
  825. remaining memory in each node is used for Movable
  826. pages. In the event, a node is too small to have both
  827. kernelcore and Movable pages, kernelcore pages will
  828. take priority and other nodes will have a larger number
  829. of kernelcore pages. The Movable zone is used for the
  830. allocation of pages that may be reclaimed or moved
  831. by the page migration subsystem. This means that
  832. HugeTLB pages may not be allocated from this zone.
  833. Note that allocations like PTEs-from-HighMem still
  834. use the HighMem zone if it exists, and the Normal
  835. zone if it does not.
  836. movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  837. is similar to kernelcore except it specifies the
  838. amount of memory used for migratable allocations.
  839. If both kernelcore and movablecore is specified,
  840. then kernelcore will be at *least* the specified
  841. value but may be more. If movablecore on its own
  842. is specified, the administrator must be careful
  843. that the amount of memory usable for all allocations
  844. is not too small.
  845. keepinitrd [HW,ARM]
  846. kstack=N [X86-32,X86-64] Print N words from the kernel stack
  847. in oops dumps.
  848. kgdboc= [HW] kgdb over consoles.
  849. Requires a tty driver that supports console polling.
  850. (only serial suported for now)
  851. Format: <serial_device>[,baud]
  852. kmac= [MIPS] korina ethernet MAC address.
  853. Configure the RouterBoard 532 series on-chip
  854. Ethernet adapter MAC address.
  855. l2cr= [PPC]
  856. l3cr= [PPC]
  857. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  858. disabled it.
  859. lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
  860. C2 power state.
  861. libata.dma= [LIBATA] DMA control
  862. libata.dma=0 Disable all PATA and SATA DMA
  863. libata.dma=1 PATA and SATA Disk DMA only
  864. libata.dma=2 ATAPI (CDROM) DMA only
  865. libata.dma=4 Compact Flash DMA only
  866. Combinations also work, so libata.dma=3 enables DMA
  867. for disks and CDROMs, but not CFs.
  868. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  869. when set.
  870. Format: <int>
  871. libata.force= [LIBATA] Force configurations. The format is comma
  872. separated list of "[ID:]VAL" where ID is
  873. PORT[:DEVICE]. PORT and DEVICE are decimal numbers
  874. matching port, link or device. Basically, it matches
  875. the ATA ID string printed on console by libata. If
  876. the whole ID part is omitted, the last PORT and DEVICE
  877. values are used. If ID hasn't been specified yet, the
  878. configuration applies to all ports, links and devices.
  879. If only DEVICE is omitted, the parameter applies to
  880. the port and all links and devices behind it. DEVICE
  881. number of 0 either selects the first device or the
  882. first fan-out link behind PMP device. It does not
  883. select the host link. DEVICE number of 15 selects the
  884. host link and device attached to it.
  885. The VAL specifies the configuration to force. As long
  886. as there's no ambiguity shortcut notation is allowed.
  887. For example, both 1.5 and 1.5G would work for 1.5Gbps.
  888. The following configurations can be forced.
  889. * Cable type: 40c, 80c, short40c, unk, ign or sata.
  890. Any ID with matching PORT is used.
  891. * SATA link speed limit: 1.5Gbps or 3.0Gbps.
  892. * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
  893. udma[/][16,25,33,44,66,100,133] notation is also
  894. allowed.
  895. * [no]ncq: Turn on or off NCQ.
  896. * nohrst, nosrst, norst: suppress hard, soft
  897. and both resets.
  898. If there are multiple matching configurations changing
  899. the same attribute, the last one is used.
  900. load_ramdisk= [RAM] List of ramdisks to load from floppy
  901. See Documentation/blockdev/ramdisk.txt.
  902. lockd.nlm_grace_period=P [NFS] Assign grace period.
  903. Format: <integer>
  904. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  905. Format: <integer>
  906. lockd.nlm_timeout=T [NFS] Assign timeout value.
  907. Format: <integer>
  908. lockd.nlm_udpport=M [NFS] Assign UDP port.
  909. Format: <integer>
  910. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  911. Format: <irq>
  912. loglevel= All Kernel Messages with a loglevel smaller than the
  913. console loglevel will be printed to the console. It can
  914. also be changed with klogd or other programs. The
  915. loglevels are defined as follows:
  916. 0 (KERN_EMERG) system is unusable
  917. 1 (KERN_ALERT) action must be taken immediately
  918. 2 (KERN_CRIT) critical conditions
  919. 3 (KERN_ERR) error conditions
  920. 4 (KERN_WARNING) warning conditions
  921. 5 (KERN_NOTICE) normal but significant condition
  922. 6 (KERN_INFO) informational
  923. 7 (KERN_DEBUG) debug-level messages
  924. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  925. Format: { n | nk | nM }
  926. n must be a power of two. The default size
  927. is set in the kernel config file.
  928. logo.nologo [FB] Disables display of the built-in Linux logo.
  929. This may be used to provide more screen space for
  930. kernel log messages and is useful when debugging
  931. kernel boot problems.
  932. lp=0 [LP] Specify parallel ports to use, e.g,
  933. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  934. lp=reset first parallel port). 'lp=0' disables the
  935. lp=auto printer driver. 'lp=reset' (which can be
  936. specified in addition to the ports) causes
  937. attached printers to be reset. Using
  938. lp=port1,port2,... specifies the parallel ports
  939. to associate lp devices with, starting with
  940. lp0. A port specification may be 'none' to skip
  941. that lp device, or a parport name such as
  942. 'parport0'. Specifying 'lp=auto' instead of a
  943. port specification list means that device IDs
  944. from each port should be examined, to see if
  945. an IEEE 1284-compliant printer is attached; if
  946. so, the driver will manage that printer.
  947. See also header of drivers/char/lp.c.
  948. lpj=n [KNL]
  949. Sets loops_per_jiffy to given constant, thus avoiding
  950. time-consuming boot-time autodetection (up to 250 ms per
  951. CPU). 0 enables autodetection (default). To determine
  952. the correct value for your kernel, boot with normal
  953. autodetection and see what value is printed. Note that
  954. on SMP systems the preset will be applied to all CPUs,
  955. which is likely to cause problems if your CPUs need
  956. significantly divergent settings. An incorrect value
  957. will cause delays in the kernel to be wrong, leading to
  958. unpredictable I/O errors and other breakage. Although
  959. unlikely, in the extreme case this might damage your
  960. hardware.
  961. ltpc= [NET]
  962. Format: <io>,<irq>,<dma>
  963. mac5380= [HW,SCSI] Format:
  964. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  965. machvec= [IA64] Force the use of a particular machine-vector
  966. (machvec) in a generic kernel.
  967. Example: machvec=hpzx1_swiotlb
  968. max_loop= [LOOP] Maximum number of loopback devices that can
  969. be mounted
  970. Format: <1-256>
  971. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  972. should make use of. maxcpus=n : n >= 0 limits the
  973. kernel to using 'n' processors. n=0 is a special case,
  974. it is equivalent to "nosmp", which also disables
  975. the IO APIC.
  976. max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
  977. or equal to this physical address is ignored.
  978. max_luns= [SCSI] Maximum number of LUNs to probe.
  979. Should be between 1 and 2^32-1.
  980. max_report_luns=
  981. [SCSI] Maximum number of LUNs received.
  982. Should be between 1 and 16384.
  983. mcatest= [IA-64]
  984. mce [X86-32] Machine Check Exception
  985. mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
  986. md= [HW] RAID subsystems devices and level
  987. See Documentation/md.txt.
  988. mdacon= [MDA]
  989. Format: <first>,<last>
  990. Specifies range of consoles to be captured by the MDA.
  991. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  992. Amount of memory to be used when the kernel is not able
  993. to see the whole system memory or for test.
  994. [X86-32] Use together with memmap= to avoid physical
  995. address space collisions. Without memmap= PCI devices
  996. could be placed at addresses belonging to unused RAM.
  997. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  998. memory.
  999. memchunk=nn[KMG]
  1000. [KNL,SH] Allow user to override the default size for
  1001. per-device physically contiguous DMA buffers.
  1002. memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
  1003. E820 memory map, as specified by the user.
  1004. Such memmap=exactmap lines can be constructed based on
  1005. BIOS output or other requirements. See the memmap=nn@ss
  1006. option description.
  1007. memmap=nn[KMG]@ss[KMG]
  1008. [KNL] Force usage of a specific region of memory
  1009. Region of memory to be used, from ss to ss+nn.
  1010. memmap=nn[KMG]#ss[KMG]
  1011. [KNL,ACPI] Mark specific memory as ACPI data.
  1012. Region of memory to be used, from ss to ss+nn.
  1013. memmap=nn[KMG]$ss[KMG]
  1014. [KNL,ACPI] Mark specific memory as reserved.
  1015. Region of memory to be used, from ss to ss+nn.
  1016. Example: Exclude memory from 0x18690000-0x1869ffff
  1017. memmap=64K$0x18690000
  1018. or
  1019. memmap=0x10000$0x18690000
  1020. memory_corruption_check=0/1 [X86]
  1021. Some BIOSes seem to corrupt the first 64k of
  1022. memory when doing things like suspend/resume.
  1023. Setting this option will scan the memory
  1024. looking for corruption. Enabling this will
  1025. both detect corruption and prevent the kernel
  1026. from using the memory being corrupted.
  1027. However, its intended as a diagnostic tool; if
  1028. repeatable BIOS-originated corruption always
  1029. affects the same memory, you can use memmap=
  1030. to prevent the kernel from using that memory.
  1031. memory_corruption_check_size=size [X86]
  1032. By default it checks for corruption in the low
  1033. 64k, making this memory unavailable for normal
  1034. use. Use this parameter to scan for
  1035. corruption in more or less memory.
  1036. memory_corruption_check_period=seconds [X86]
  1037. By default it checks for corruption every 60
  1038. seconds. Use this parameter to check at some
  1039. other rate. 0 disables periodic checking.
  1040. memtest= [KNL,X86] Enable memtest
  1041. Format: <integer>
  1042. range: 0,4 : pattern number
  1043. default : 0 <disable>
  1044. meye.*= [HW] Set MotionEye Camera parameters
  1045. See Documentation/video4linux/meye.txt.
  1046. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  1047. Multi-Function General Purpose Timers on AMD Geode
  1048. platforms.
  1049. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  1050. the BIOS has incorrectly applied a workaround. TinyBIOS
  1051. version 0.98 is known to be affected, 0.99 fixes the
  1052. problem by letting the user disable the workaround.
  1053. mga= [HW,DRM]
  1054. min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
  1055. physical address is ignored.
  1056. mminit_loglevel=
  1057. [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
  1058. parameter allows control of the logging verbosity for
  1059. the additional memory initialisation checks. A value
  1060. of 0 disables mminit logging and a level of 4 will
  1061. log everything. Information is printed at KERN_DEBUG
  1062. so loglevel=8 may also need to be specified.
  1063. mousedev.tap_time=
  1064. [MOUSE] Maximum time between finger touching and
  1065. leaving touchpad surface for touch to be considered
  1066. a tap and be reported as a left button click (for
  1067. touchpads working in absolute mode only).
  1068. Format: <msecs>
  1069. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  1070. reporting absolute coordinates, such as tablets
  1071. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  1072. reporting absolute coordinates, such as tablets
  1073. mpu401= [HW,OSS]
  1074. Format: <io>,<irq>
  1075. MTD_Partition= [MTD]
  1076. Format: <name>,<region-number>,<size>,<offset>
  1077. MTD_Region= [MTD] Format:
  1078. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  1079. mtdparts= [MTD]
  1080. See drivers/mtd/cmdlinepart.c.
  1081. mtdset= [ARM]
  1082. ARM/S3C2412 JIVE boot control
  1083. See arch/arm/mach-s3c2412/mach-jive.c
  1084. mtouchusb.raw_coordinates=
  1085. [HW] Make the MicroTouch USB driver use raw coordinates
  1086. ('y', default) or cooked coordinates ('n')
  1087. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  1088. NCR_D700= [HW,SCSI]
  1089. See header of drivers/scsi/NCR_D700.c.
  1090. ncr5380= [HW,SCSI]
  1091. ncr53c400= [HW,SCSI]
  1092. ncr53c400a= [HW,SCSI]
  1093. ncr53c406a= [HW,SCSI]
  1094. ncr53c8xx= [HW,SCSI]
  1095. netdev= [NET] Network devices parameters
  1096. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  1097. Note that mem_start is often overloaded to mean
  1098. something different and driver-specific.
  1099. This usage is only documented in each driver source
  1100. file if at all.
  1101. nf_conntrack.acct=
  1102. [NETFILTER] Enable connection tracking flow accounting
  1103. 0 to disable accounting
  1104. 1 to enable accounting
  1105. Default value depends on CONFIG_NF_CT_ACCT that is
  1106. going to be removed in 2.6.29.
  1107. nfsaddrs= [NFS]
  1108. See Documentation/filesystems/nfsroot.txt.
  1109. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  1110. See Documentation/filesystems/nfsroot.txt.
  1111. nfs.callback_tcpport=
  1112. [NFS] set the TCP port on which the NFSv4 callback
  1113. channel should listen.
  1114. nfs.idmap_cache_timeout=
  1115. [NFS] set the maximum lifetime for idmapper cache
  1116. entries.
  1117. nfs.enable_ino64=
  1118. [NFS] enable 64-bit inode numbers.
  1119. If zero, the NFS client will fake up a 32-bit inode
  1120. number for the readdir() and stat() syscalls instead
  1121. of returning the full 64-bit number.
  1122. The default is to return 64-bit inode numbers.
  1123. nmi_debug= [KNL,AVR32] Specify one or more actions to take
  1124. when a NMI is triggered.
  1125. Format: [state][,regs][,debounce][,die]
  1126. nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
  1127. Format: [panic,][num]
  1128. Valid num: 0,1,2
  1129. 0 - turn nmi_watchdog off
  1130. 1 - use the IO-APIC timer for the NMI watchdog
  1131. 2 - use the local APIC for the NMI watchdog using
  1132. a performance counter. Note: This will use one performance
  1133. counter and the local APIC's performance vector.
  1134. When panic is specified panic when an NMI watchdog timeout occurs.
  1135. This is useful when you use a panic=... timeout and need the box
  1136. quickly up again.
  1137. Instead of 1 and 2 it is possible to use the following
  1138. symbolic names: lapic and ioapic
  1139. Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
  1140. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  1141. emulation library even if a 387 maths coprocessor
  1142. is present.
  1143. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  1144. caches in the slab allocator. Saves per-node memory,
  1145. but will impact performance.
  1146. noalign [KNL,ARM]
  1147. noapic [SMP,APIC] Tells the kernel to not make use of any
  1148. IOAPICs that may be present in the system.
  1149. nobats [PPC] Do not use BATs for mapping kernel lowmem
  1150. on "Classic" PPC cores.
  1151. nocache [ARM]
  1152. nodelayacct [KNL] Disable per-task delay accounting
  1153. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  1154. nodsp [SH] Disable hardware DSP at boot time.
  1155. noefi [X86-32,X86-64] Disable EFI runtime services support.
  1156. noexec [IA-64]
  1157. noexec [X86-32,X86-64]
  1158. On X86-32 available only on PAE configured kernels.
  1159. noexec=on: enable non-executable mappings (default)
  1160. noexec=off: disable non-executable mappings
  1161. noexec32 [X86-64]
  1162. This affects only 32-bit executables.
  1163. noexec32=on: enable non-executable mappings (default)
  1164. read doesn't imply executable mappings
  1165. noexec32=off: disable non-executable mappings
  1166. read implies executable mappings
  1167. nofpu [SH] Disable hardware FPU at boot time.
  1168. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  1169. register save and restore. The kernel will only save
  1170. legacy floating-point registers on task switch.
  1171. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  1172. nohlt [BUGS=ARM,SH]
  1173. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  1174. instruction doesn't work correctly and not to
  1175. use it.
  1176. no_file_caps Tells the kernel not to honor file capabilities. The
  1177. only way then for a file to be executed with privilege
  1178. is to be setuid root or executed by root.
  1179. nohalt [IA-64] Tells the kernel not to use the power saving
  1180. function PAL_HALT_LIGHT when idle. This increases
  1181. power-consumption. On the positive side, it reduces
  1182. interrupt wake-up latency, which may improve performance
  1183. in certain environments such as networked servers or
  1184. real-time systems.
  1185. nohz= [KNL] Boottime enable/disable dynamic ticks
  1186. Valid arguments: on, off
  1187. Default: on
  1188. noirqdebug [X86-32] Disables the code which attempts to detect and
  1189. disable unhandled interrupt sources.
  1190. no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
  1191. broken timer IRQ sources.
  1192. noisapnp [ISAPNP] Disables ISA PnP code.
  1193. noinitrd [RAM] Tells the kernel not to load any configured
  1194. initial RAM disk.
  1195. nointroute [IA-64]
  1196. nojitter [IA64] Disables jitter checking for ITC timers.
  1197. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  1198. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  1199. nox2apic [X86-64,APIC] Do not enable x2APIC mode.
  1200. x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
  1201. default x2apic cluster mode on platforms
  1202. supporting x2apic.
  1203. noltlbs [PPC] Do not use large page/tlb entries for kernel
  1204. lowmem mapping on PPC40x.
  1205. nomca [IA-64] Disable machine check abort handling
  1206. nomce [X86-32] Machine Check Exception
  1207. nomfgpt [X86-32] Disable Multi-Function General Purpose
  1208. Timer usage (for AMD Geode machines).
  1209. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  1210. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1211. with UP alternatives
  1212. noresidual [PPC] Don't use residual data on PReP machines.
  1213. noresume [SWSUSP] Disables resume and restores original swap
  1214. space.
  1215. no-scroll [VGA] Disables scrollback.
  1216. This is required for the Braillex ib80-piezo Braille
  1217. reader made by F.H. Papenmeier (Germany).
  1218. nosbagart [IA-64]
  1219. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1220. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1221. and disable the IO APIC. legacy for "maxcpus=0".
  1222. nosoftlockup [KNL] Disable the soft-lockup detector.
  1223. nosync [HW,M68K] Disables sync negotiation for all devices.
  1224. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1225. nousb [USB] Disable the USB subsystem
  1226. nowb [ARM]
  1227. nptcg= [IA64] Override max number of concurrent global TLB
  1228. purges which is reported from either PAL_VM_SUMMARY or
  1229. SAL PALO.
  1230. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1231. one of ['zone', 'node', 'default'] can be specified
  1232. This can be set from sysctl after boot.
  1233. See Documentation/sysctl/vm.txt for details.
  1234. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1235. olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
  1236. Rather than timing out after 20 ms if an EC
  1237. command is not properly ACKed, override the length
  1238. of the timeout. We have interrupts disabled while
  1239. waiting for the ACK, so if this is set too high
  1240. interrupts *may* be lost!
  1241. opl3= [HW,OSS]
  1242. Format: <io>
  1243. oprofile.timer= [HW]
  1244. Use timer interrupt instead of performance counters
  1245. osst= [HW,SCSI] SCSI Tape Driver
  1246. Format: <buffer_size>,<write_threshold>
  1247. See also Documentation/scsi/st.txt.
  1248. panic= [KNL] Kernel behaviour on panic
  1249. Format: <timeout>
  1250. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1251. connected to, default is 0.
  1252. Format: <parport#>
  1253. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1254. 0 for XT, 1 for AT (default is AT).
  1255. Format: <mode>
  1256. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1257. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1258. Use 'auto' to force the driver to use any
  1259. IRQ/DMA settings detected (the default is to
  1260. ignore detected IRQ/DMA settings because of
  1261. possible conflicts). You can specify the base
  1262. address, IRQ, and DMA settings; IRQ and DMA
  1263. should be numbers, or 'auto' (for using detected
  1264. settings on that particular port), or 'nofifo'
  1265. (to avoid using a FIFO even if it is detected).
  1266. Parallel ports are assigned in the order they
  1267. are specified on the command line, starting
  1268. with parport0.
  1269. parport_init_mode= [HW,PPT]
  1270. Configure VIA parallel port to operate in
  1271. a specific mode. This is necessary on Pegasos
  1272. computer where firmware has no options for setting
  1273. up parallel port mode and sets it to spp.
  1274. Currently this function knows 686a and 8231 chips.
  1275. Format: [spp|ps2|epp|ecp|ecpepp]
  1276. pas2= [HW,OSS] Format:
  1277. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1278. pas16= [HW,SCSI]
  1279. See header of drivers/scsi/pas16.c.
  1280. pause_on_oops=
  1281. Halt all CPUs after the first oops has been printed for
  1282. the specified number of seconds. This is to be used if
  1283. your oopses keep scrolling off the screen.
  1284. pcbit= [HW,ISDN]
  1285. pcd. [PARIDE]
  1286. See header of drivers/block/paride/pcd.c.
  1287. See also Documentation/blockdev/paride.txt.
  1288. pci=option[,option...] [PCI] various PCI subsystem options:
  1289. off [X86] don't probe for the PCI bus
  1290. bios [X86-32] force use of PCI BIOS, don't access
  1291. the hardware directly. Use this if your machine
  1292. has a non-standard PCI host bridge.
  1293. nobios [X86-32] disallow use of PCI BIOS, only direct
  1294. hardware access methods are allowed. Use this
  1295. if you experience crashes upon bootup and you
  1296. suspect they are caused by the BIOS.
  1297. conf1 [X86] Force use of PCI Configuration
  1298. Mechanism 1.
  1299. conf2 [X86] Force use of PCI Configuration
  1300. Mechanism 2.
  1301. noaer [PCIE] If the PCIEAER kernel config parameter is
  1302. enabled, this kernel boot option can be used to
  1303. disable the use of PCIE advanced error reporting.
  1304. nodomains [PCI] Disable support for multiple PCI
  1305. root domains (aka PCI segments, in ACPI-speak).
  1306. nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
  1307. Configuration
  1308. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1309. enabled, this kernel boot option can be used to
  1310. disable the use of MSI interrupts system-wide.
  1311. noioapicquirk [APIC] Disable all boot interrupt quirks.
  1312. Safety option to keep boot IRQs enabled. This
  1313. should never be necessary.
  1314. ioapicreroute [APIC] Enable rerouting of boot IRQs to the
  1315. primary IO-APIC for bridges that cannot disable
  1316. boot IRQs. This fixes a source of spurious IRQs
  1317. when the system masks IRQs.
  1318. noioapicreroute [APIC] Disable workaround that uses the
  1319. boot IRQ equivalent of an IRQ that connects to
  1320. a chipset where boot IRQs cannot be disabled.
  1321. The opposite of ioapicreroute.
  1322. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1323. routing table. These calls are known to be buggy
  1324. on several machines and they hang the machine
  1325. when used, but on other computers it's the only
  1326. way to get the interrupt routing table. Try
  1327. this option if the kernel is unable to allocate
  1328. IRQs or discover secondary PCI buses on your
  1329. motherboard.
  1330. rom [X86] Assign address space to expansion ROMs.
  1331. Use with caution as certain devices share
  1332. address decoders between ROMs and other
  1333. resources.
  1334. norom [X86] Do not assign address space to
  1335. expansion ROMs that do not already have
  1336. BIOS assigned address ranges.
  1337. irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
  1338. assigned automatically to PCI devices. You can
  1339. make the kernel exclude IRQs of your ISA cards
  1340. this way.
  1341. pirqaddr=0xAAAAA [X86] Specify the physical address
  1342. of the PIRQ table (normally generated
  1343. by the BIOS) if it is outside the
  1344. F0000h-100000h range.
  1345. lastbus=N [X86] Scan all buses thru bus #N. Can be
  1346. useful if the kernel is unable to find your
  1347. secondary buses and you want to tell it
  1348. explicitly which ones they are.
  1349. assign-busses [X86] Always assign all PCI bus
  1350. numbers ourselves, overriding
  1351. whatever the firmware may have done.
  1352. usepirqmask [X86] Honor the possible IRQ mask stored
  1353. in the BIOS $PIR table. This is needed on
  1354. some systems with broken BIOSes, notably
  1355. some HP Pavilion N5400 and Omnibook XE3
  1356. notebooks. This will have no effect if ACPI
  1357. IRQ routing is enabled.
  1358. noacpi [X86] Do not use ACPI for IRQ routing
  1359. or for PCI scanning.
  1360. use_crs [X86] Use _CRS for PCI resource
  1361. allocation.
  1362. routeirq Do IRQ routing for all PCI devices.
  1363. This is normally done in pci_enable_device(),
  1364. so this option is a temporary workaround
  1365. for broken drivers that don't call it.
  1366. skip_isa_align [X86] do not align io start addr, so can
  1367. handle more pci cards
  1368. firmware [ARM] Do not re-enumerate the bus but instead
  1369. just use the configuration from the
  1370. bootloader. This is currently used on
  1371. IXP2000 systems where the bus has to be
  1372. configured a certain way for adjunct CPUs.
  1373. noearly [X86] Don't do any early type 1 scanning.
  1374. This might help on some broken boards which
  1375. machine check when some devices' config space
  1376. is read. But various workarounds are disabled
  1377. and some IOMMU drivers will not work.
  1378. bfsort Sort PCI devices into breadth-first order.
  1379. This sorting is done to get a device
  1380. order compatible with older (<= 2.4) kernels.
  1381. nobfsort Don't sort PCI devices into breadth-first order.
  1382. cbiosize=nn[KMG] The fixed amount of bus space which is
  1383. reserved for the CardBus bridge's IO window.
  1384. The default value is 256 bytes.
  1385. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1386. reserved for the CardBus bridge's memory
  1387. window. The default value is 64 megabytes.
  1388. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
  1389. Management.
  1390. off Disable ASPM.
  1391. force Enable ASPM even on devices that claim not to support it.
  1392. WARNING: Forcing ASPM on may cause system lockups.
  1393. pcmv= [HW,PCMCIA] BadgePAD 4
  1394. pd. [PARIDE]
  1395. See Documentation/blockdev/paride.txt.
  1396. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1397. boot time.
  1398. Format: { 0 | 1 }
  1399. See arch/parisc/kernel/pdc_chassis.c
  1400. pf. [PARIDE]
  1401. See Documentation/blockdev/paride.txt.
  1402. pg. [PARIDE]
  1403. See Documentation/blockdev/paride.txt.
  1404. pirq= [SMP,APIC] Manual mp-table setup
  1405. See Documentation/x86/i386/IO-APIC.txt.
  1406. plip= [PPT,NET] Parallel port network link
  1407. Format: { parport<nr> | timid | 0 }
  1408. See also Documentation/parport.txt.
  1409. pmtmr= [X86] Manual setup of pmtmr I/O Port.
  1410. Override pmtimer IOPort with a hex value.
  1411. e.g. pmtmr=0x508
  1412. pnp.debug [PNP]
  1413. Enable PNP debug messages. This depends on the
  1414. CONFIG_PNP_DEBUG_MESSAGES option.
  1415. pnpacpi= [ACPI]
  1416. { off }
  1417. pnpbios= [ISAPNP]
  1418. { on | off | curr | res | no-curr | no-res }
  1419. pnp_reserve_irq=
  1420. [ISAPNP] Exclude IRQs for the autoconfiguration
  1421. pnp_reserve_dma=
  1422. [ISAPNP] Exclude DMAs for the autoconfiguration
  1423. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1424. Ranges are in pairs (I/O port base and size).
  1425. pnp_reserve_mem=
  1426. [ISAPNP] Exclude memory regions for the
  1427. autoconfiguration.
  1428. Ranges are in pairs (memory base and size).
  1429. dynamic_printk
  1430. Enables pr_debug()/dev_dbg() calls if
  1431. CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
  1432. be switched on/off via <debugfs>/dynamic_printk/modules
  1433. print-fatal-signals=
  1434. [KNL] debug: print fatal signals
  1435. print-fatal-signals=1: print segfault info to
  1436. the kernel console.
  1437. default: off.
  1438. printk.time= Show timing data prefixed to each printk message line
  1439. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1440. profile= [KNL] Enable kernel profiling via /proc/profile
  1441. Format: [schedule,]<number>
  1442. Param: "schedule" - profile schedule points.
  1443. Param: <number> - step/bucket size as a power of 2 for
  1444. statistical time based profiling.
  1445. Param: "sleep" - profile D-state sleeping (millisecs).
  1446. Requires CONFIG_SCHEDSTATS
  1447. Param: "kvm" - profile VM exits.
  1448. processor.max_cstate= [HW,ACPI]
  1449. Limit processor to maximum C-state
  1450. max_cstate=9 overrides any DMI blacklist limit.
  1451. processor.nocst [HW,ACPI]
  1452. Ignore the _CST method to determine C-states,
  1453. instead using the legacy FADT method
  1454. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1455. before loading.
  1456. See Documentation/blockdev/ramdisk.txt.
  1457. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1458. probe for; one of (bare|imps|exps|lifebook|any).
  1459. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1460. per second.
  1461. psmouse.resetafter= [HW,MOUSE]
  1462. Try to reset the device after so many bad packets
  1463. (0 = never).
  1464. psmouse.resolution=
  1465. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1466. psmouse.smartscroll=
  1467. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1468. 0 = disabled, 1 = enabled (default).
  1469. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1470. Format:
  1471. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1472. pt. [PARIDE]
  1473. See Documentation/blockdev/paride.txt.
  1474. pty.legacy_count=
  1475. [KNL] Number of legacy pty's. Overwrites compiled-in
  1476. default number.
  1477. quiet [KNL] Disable most log messages
  1478. r128= [HW,DRM]
  1479. raid= [HW,RAID]
  1480. See Documentation/md.txt.
  1481. ramdisk_blocksize= [RAM]
  1482. See Documentation/blockdev/ramdisk.txt.
  1483. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1484. See Documentation/blockdev/ramdisk.txt.
  1485. rcupdate.blimit= [KNL,BOOT]
  1486. Set maximum number of finished RCU callbacks to process
  1487. in one batch.
  1488. rcupdate.qhimark= [KNL,BOOT]
  1489. Set threshold of queued
  1490. RCU callbacks over which batch limiting is disabled.
  1491. rcupdate.qlowmark= [KNL,BOOT]
  1492. Set threshold of queued RCU callbacks below which
  1493. batch limiting is re-enabled.
  1494. rdinit= [KNL]
  1495. Format: <full_path>
  1496. Run specified binary instead of /init from the ramdisk,
  1497. used for early userspace startup. See initrd.
  1498. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1499. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1500. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1501. relax_domain_level=
  1502. [KNL, SMP] Set scheduler's default relax_domain_level.
  1503. See Documentation/cpusets.txt.
  1504. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1505. reservetop= [X86-32]
  1506. Format: nn[KMG]
  1507. Reserves a hole at the top of the kernel virtual
  1508. address space.
  1509. reset_devices [KNL] Force drivers to reset the underlying device
  1510. during initialization.
  1511. resume= [SWSUSP]
  1512. Specify the partition device for software suspend
  1513. resume_offset= [SWSUSP]
  1514. Specify the offset from the beginning of the partition
  1515. given by "resume=" at which the swap header is located,
  1516. in <PAGE_SIZE> units (needed only for swap files).
  1517. See Documentation/power/swsusp-and-swap-files.txt
  1518. retain_initrd [RAM] Keep initrd memory after extraction
  1519. rhash_entries= [KNL,NET]
  1520. Set number of hash buckets for route cache
  1521. riscom8= [HW,SERIAL]
  1522. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1523. ro [KNL] Mount root device read-only on boot
  1524. root= [KNL] Root filesystem
  1525. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1526. mount the root filesystem
  1527. rootflags= [KNL] Set root filesystem mount option string
  1528. rootfstype= [KNL] Set root filesystem type
  1529. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1530. Useful for devices that are detected asynchronously
  1531. (e.g. USB and MMC devices).
  1532. root_plug.vendor_id=
  1533. [ROOTPLUG] Override the default vendor ID
  1534. root_plug.product_id=
  1535. [ROOTPLUG] Override the default product ID
  1536. root_plug.debug=
  1537. [ROOTPLUG] Enable debugging output
  1538. rw [KNL] Mount root device read-write on boot
  1539. S [KNL] Run init in single mode
  1540. sa1100ir [NET]
  1541. See drivers/net/irda/sa1100_ir.c.
  1542. sbni= [NET] Granch SBNI12 leased line adapter
  1543. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1544. Format: <io>[,<timeout>[,<isapnp>]]
  1545. scsi_debug_*= [SCSI]
  1546. See drivers/scsi/scsi_debug.c.
  1547. scsi_default_dev_flags=
  1548. [SCSI] SCSI default device flags
  1549. Format: <integer>
  1550. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1551. Format: <vendor>:<model>:<flags>
  1552. (flags are integer value)
  1553. scsi_logging_level= [SCSI] a bit mask of logging levels
  1554. See drivers/scsi/scsi_logging.h for bits. Also
  1555. settable via sysctl at dev.scsi.logging_level
  1556. (/proc/sys/dev/scsi/logging_level).
  1557. There is also a nice 'scsi_logging_level' script in the
  1558. S390-tools package, available for download at
  1559. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1560. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1561. discovered. async scans them in kernel threads,
  1562. allowing boot to proceed. none ignores them, expecting
  1563. user space to do the scan.
  1564. selinux [SELINUX] Disable or enable SELinux at boot time.
  1565. Format: { "0" | "1" }
  1566. See security/selinux/Kconfig help text.
  1567. 0 -- disable.
  1568. 1 -- enable.
  1569. Default value is set via kernel config option.
  1570. If enabled at boot time, /selinux/disable can be used
  1571. later to disable prior to initial policy load.
  1572. selinux_compat_net =
  1573. [SELINUX] Set initial selinux_compat_net flag value.
  1574. Format: { "0" | "1" }
  1575. 0 -- use new secmark-based packet controls
  1576. 1 -- use legacy packet controls
  1577. Default value is 0 (preferred).
  1578. Value can be changed at runtime via
  1579. /selinux/compat_net.
  1580. serialnumber [BUGS=X86-32]
  1581. shapers= [NET]
  1582. Maximal number of shapers.
  1583. show_msr= [x86] show boot-time MSR settings
  1584. Format: { <integer> }
  1585. Show boot-time (BIOS-initialized) MSR settings.
  1586. The parameter means the number of CPUs to show,
  1587. for example 1 means boot CPU only.
  1588. sim710= [SCSI,HW]
  1589. See header of drivers/scsi/sim710.c.
  1590. simeth= [IA-64]
  1591. simscsi=
  1592. slram= [HW,MTD]
  1593. slub_debug[=options[,slabs]] [MM, SLUB]
  1594. Enabling slub_debug allows one to determine the
  1595. culprit if slab objects become corrupted. Enabling
  1596. slub_debug can create guard zones around objects and
  1597. may poison objects when not in use. Also tracks the
  1598. last alloc / free. For more information see
  1599. Documentation/vm/slub.txt.
  1600. slub_max_order= [MM, SLUB]
  1601. Determines the maximum allowed order for slabs.
  1602. A high setting may cause OOMs due to memory
  1603. fragmentation. For more information see
  1604. Documentation/vm/slub.txt.
  1605. slub_min_objects= [MM, SLUB]
  1606. The minimum number of objects per slab. SLUB will
  1607. increase the slab order up to slub_max_order to
  1608. generate a sufficiently large slab able to contain
  1609. the number of objects indicated. The higher the number
  1610. of objects the smaller the overhead of tracking slabs
  1611. and the less frequently locks need to be acquired.
  1612. For more information see Documentation/vm/slub.txt.
  1613. slub_min_order= [MM, SLUB]
  1614. Determines the mininum page order for slabs. Must be
  1615. lower than slub_max_order.
  1616. For more information see Documentation/vm/slub.txt.
  1617. slub_nomerge [MM, SLUB]
  1618. Disable merging of slabs with similar size. May be
  1619. necessary if there is some reason to distinguish
  1620. allocs to different slabs. Debug options disable
  1621. merging on their own.
  1622. For more information see Documentation/vm/slub.txt.
  1623. smart2= [HW]
  1624. Format: <io1>[,<io2>[,...,<io8>]]
  1625. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1626. attempt to substitute SMP alternatives once at boot.
  1627. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1628. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1629. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1630. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1631. smsc-ircc2.ircc_irq= [HW] IRQ line
  1632. smsc-ircc2.ircc_dma= [HW] DMA channel
  1633. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1634. 0: Toshiba Satellite 1800 (GP data pin select)
  1635. 1: Fast pin select (default)
  1636. 2: ATC IRMode
  1637. snd-ad1816a= [HW,ALSA]
  1638. snd-ad1848= [HW,ALSA]
  1639. snd-ali5451= [HW,ALSA]
  1640. snd-als100= [HW,ALSA]
  1641. snd-als4000= [HW,ALSA]
  1642. snd-azt2320= [HW,ALSA]
  1643. snd-cmi8330= [HW,ALSA]
  1644. snd-cmipci= [HW,ALSA]
  1645. snd-cs4231= [HW,ALSA]
  1646. snd-cs4232= [HW,ALSA]
  1647. snd-cs4236= [HW,ALSA]
  1648. snd-cs4281= [HW,ALSA]
  1649. snd-cs46xx= [HW,ALSA]
  1650. snd-dt019x= [HW,ALSA]
  1651. snd-dummy= [HW,ALSA]
  1652. snd-emu10k1= [HW,ALSA]
  1653. snd-ens1370= [HW,ALSA]
  1654. snd-ens1371= [HW,ALSA]
  1655. snd-es968= [HW,ALSA]
  1656. snd-es1688= [HW,ALSA]
  1657. snd-es18xx= [HW,ALSA]
  1658. snd-es1938= [HW,ALSA]
  1659. snd-es1968= [HW,ALSA]
  1660. snd-fm801= [HW,ALSA]
  1661. snd-gusclassic= [HW,ALSA]
  1662. snd-gusextreme= [HW,ALSA]
  1663. snd-gusmax= [HW,ALSA]
  1664. snd-hdsp= [HW,ALSA]
  1665. snd-ice1712= [HW,ALSA]
  1666. snd-intel8x0= [HW,ALSA]
  1667. snd-interwave= [HW,ALSA]
  1668. snd-interwave-stb=
  1669. [HW,ALSA]
  1670. snd-korg1212= [HW,ALSA]
  1671. snd-maestro3= [HW,ALSA]
  1672. snd-mpu401= [HW,ALSA]
  1673. snd-mtpav= [HW,ALSA]
  1674. snd-nm256= [HW,ALSA]
  1675. snd-opl3sa2= [HW,ALSA]
  1676. snd-opti92x-ad1848=
  1677. [HW,ALSA]
  1678. snd-opti92x-cs4231=
  1679. [HW,ALSA]
  1680. snd-opti93x= [HW,ALSA]
  1681. snd-pmac= [HW,ALSA]
  1682. snd-rme32= [HW,ALSA]
  1683. snd-rme96= [HW,ALSA]
  1684. snd-rme9652= [HW,ALSA]
  1685. snd-sb8= [HW,ALSA]
  1686. snd-sb16= [HW,ALSA]
  1687. snd-sbawe= [HW,ALSA]
  1688. snd-serial= [HW,ALSA]
  1689. snd-sgalaxy= [HW,ALSA]
  1690. snd-sonicvibes= [HW,ALSA]
  1691. snd-sun-amd7930=
  1692. [HW,ALSA]
  1693. snd-sun-cs4231= [HW,ALSA]
  1694. snd-trident= [HW,ALSA]
  1695. snd-usb-audio= [HW,ALSA,USB]
  1696. snd-via82xx= [HW,ALSA]
  1697. snd-virmidi= [HW,ALSA]
  1698. snd-wavefront= [HW,ALSA]
  1699. snd-ymfpci= [HW,ALSA]
  1700. softlockup_panic=
  1701. [KNL] Should the soft-lockup detector generate panics.
  1702. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1703. See Documentation/sonypi.txt
  1704. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1705. See Documentation/serial/specialix.txt.
  1706. spia_io_base= [HW,MTD]
  1707. spia_fio_base=
  1708. spia_pedr=
  1709. spia_peddr=
  1710. sscape= [HW,OSS]
  1711. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1712. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1713. See Documentation/scsi/st.txt.
  1714. stacktrace [FTRACE]
  1715. Enabled the stack tracer on boot up.
  1716. sti= [PARISC,HW]
  1717. Format: <num>
  1718. Set the STI (builtin display/keyboard on the HP-PARISC
  1719. machines) console (graphic card) which should be used
  1720. as the initial boot-console.
  1721. See also comment in drivers/video/console/sticore.c.
  1722. sti_font= [HW]
  1723. See comment in drivers/video/console/sticore.c.
  1724. stifb= [HW]
  1725. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1726. sunrpc.pool_mode=
  1727. [NFS]
  1728. Control how the NFS server code allocates CPUs to
  1729. service thread pools. Depending on how many NICs
  1730. you have and where their interrupts are bound, this
  1731. option will affect which CPUs will do NFS serving.
  1732. Note: this parameter cannot be changed while the
  1733. NFS server is running.
  1734. auto the server chooses an appropriate mode
  1735. automatically using heuristics
  1736. global a single global pool contains all CPUs
  1737. percpu one pool for each CPU
  1738. pernode one pool for each NUMA node (equivalent
  1739. to global on non-NUMA machines)
  1740. swiotlb= [IA-64] Number of I/O TLB slabs
  1741. switches= [HW,M68k]
  1742. sym53c416= [HW,SCSI]
  1743. See header of drivers/scsi/sym53c416.c.
  1744. sysrq_always_enabled
  1745. [KNL]
  1746. Ignore sysrq setting - this boot parameter will
  1747. neutralize any effect of /proc/sys/kernel/sysrq.
  1748. Useful for debugging.
  1749. t128= [HW,SCSI]
  1750. See header of drivers/scsi/t128.c.
  1751. tdfx= [HW,DRM]
  1752. test_suspend= [SUSPEND]
  1753. Specify "mem" (for Suspend-to-RAM) or "standby" (for
  1754. standby suspend) as the system sleep state to briefly
  1755. enter during system startup. The system is woken from
  1756. this state using a wakeup-capable RTC alarm.
  1757. thash_entries= [KNL,NET]
  1758. Set number of hash buckets for TCP connection
  1759. thermal.act= [HW,ACPI]
  1760. -1: disable all active trip points in all thermal zones
  1761. <degrees C>: override all lowest active trip points
  1762. thermal.crt= [HW,ACPI]
  1763. -1: disable all critical trip points in all thermal zones
  1764. <degrees C>: override all critical trip points
  1765. thermal.nocrt= [HW,ACPI]
  1766. Set to disable actions on ACPI thermal zone
  1767. critical and hot trip points.
  1768. thermal.off= [HW,ACPI]
  1769. 1: disable ACPI thermal control
  1770. thermal.psv= [HW,ACPI]
  1771. -1: disable all passive trip points
  1772. <degrees C>: override all passive trip points to this value
  1773. thermal.tzp= [HW,ACPI]
  1774. Specify global default ACPI thermal zone polling rate
  1775. <deci-seconds>: poll all this frequency
  1776. 0: no polling (default)
  1777. tmscsim= [HW,SCSI]
  1778. See comment before function dc390_setup() in
  1779. drivers/scsi/tmscsim.c.
  1780. topology= [S390]
  1781. Format: {off | on}
  1782. Specify if the kernel should make use of the cpu
  1783. topology informations if the hardware supports these.
  1784. The scheduler will make use of these informations and
  1785. e.g. base its process migration decisions on it.
  1786. Default is off.
  1787. tp720= [HW,PS2]
  1788. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1789. Format:
  1790. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1791. tsc= Disable clocksource-must-verify flag for TSC.
  1792. Format: <string>
  1793. [x86] reliable: mark tsc clocksource as reliable, this
  1794. disables clocksource verification at runtime.
  1795. Used to enable high-resolution timer mode on older
  1796. hardware, and in virtualized environment.
  1797. turbografx.map[2|3]= [HW,JOY]
  1798. TurboGraFX parallel port interface
  1799. Format:
  1800. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1801. See also Documentation/input/joystick-parport.txt
  1802. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1803. See header of drivers/scsi/u14-34f.c.
  1804. uart401= [HW,OSS]
  1805. Format: <io>,<irq>
  1806. uart6850= [HW,OSS]
  1807. Format: <io>,<irq>
  1808. uhci-hcd.ignore_oc=
  1809. [USB] Ignore overcurrent events (default N).
  1810. Some badly-designed motherboards generate lots of
  1811. bogus events, for ports that aren't wired to
  1812. anything. Set this parameter to avoid log spamming.
  1813. Note that genuine overcurrent events won't be
  1814. reported either.
  1815. unknown_nmi_panic
  1816. [X86-32,X86-64]
  1817. Set unknown_nmi_panic=1 early on boot.
  1818. usbcore.autosuspend=
  1819. [USB] The autosuspend time delay (in seconds) used
  1820. for newly-detected USB devices (default 2). This
  1821. is the time required before an idle device will be
  1822. autosuspended. Devices for which the delay is set
  1823. to a negative value won't be autosuspended at all.
  1824. usbcore.usbfs_snoop=
  1825. [USB] Set to log all usbfs traffic (default 0 = off).
  1826. usbcore.blinkenlights=
  1827. [USB] Set to cycle leds on hubs (default 0 = off).
  1828. usbcore.old_scheme_first=
  1829. [USB] Start with the old device initialization
  1830. scheme (default 0 = off).
  1831. usbcore.use_both_schemes=
  1832. [USB] Try the other device initialization scheme
  1833. if the first one fails (default 1 = enabled).
  1834. usbcore.initial_descriptor_timeout=
  1835. [USB] Specifies timeout for the initial 64-byte
  1836. USB_REQ_GET_DESCRIPTOR request in milliseconds
  1837. (default 5000 = 5.0 seconds).
  1838. usbhid.mousepoll=
  1839. [USBHID] The interval which mice are to be polled at.
  1840. add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
  1841. kernel's map of available physical RAM.
  1842. vdso= [X86-32,SH,x86-64]
  1843. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  1844. vdso=1: enable VDSO (default)
  1845. vdso=0: disable VDSO mapping
  1846. vdso32= [X86-32,X86-64]
  1847. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  1848. vdso32=1: enable 32-bit VDSO (default)
  1849. vdso32=0: disable 32-bit VDSO mapping
  1850. vector= [IA-64,SMP]
  1851. vector=percpu: enable percpu vector domain
  1852. video= [FB] Frame buffer configuration
  1853. See Documentation/fb/modedb.txt.
  1854. vga= [BOOT,X86-32] Select a particular video mode
  1855. See Documentation/x86/i386/boot.txt and
  1856. Documentation/svga.txt.
  1857. Use vga=ask for menu.
  1858. This is actually a boot loader parameter; the value is
  1859. passed to the kernel using a special protocol.
  1860. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1861. size of <nn>. This can be used to increase the
  1862. minimum size (128MB on x86). It can also be used to
  1863. decrease the size and leave more room for directly
  1864. mapped kernel RAM.
  1865. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1866. Format: <command>
  1867. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1868. Format: <command>
  1869. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1870. Format: <command>
  1871. waveartist= [HW,OSS]
  1872. Format: <io>,<irq>,<dma>,<dma2>
  1873. wd33c93= [HW,SCSI]
  1874. See header of drivers/scsi/wd33c93.c.
  1875. wd7000= [HW,SCSI]
  1876. See header of drivers/scsi/wd7000.c.
  1877. wdt= [WDT] Watchdog
  1878. See Documentation/watchdog/wdt.txt.
  1879. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1880. xd_geo= See header of drivers/block/xd.c.
  1881. xirc2ps_cs= [NET,PCMCIA]
  1882. Format:
  1883. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1884. norandmaps Don't use address space randomization
  1885. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
  1886. ______________________________________________________________________
  1887. TODO:
  1888. Add documentation for ALSA options.
  1889. Add more DRM drivers.