kernel-parameters.txt 72 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. TS Appropriate touchscreen support is enabled.
  85. USB USB support is enabled.
  86. USBHID USB Human Interface Device support is enabled.
  87. V4L Video For Linux support is enabled.
  88. VGA The VGA console has been enabled.
  89. VT Virtual terminal support is enabled.
  90. WDT Watchdog support is enabled.
  91. XT IBM PC/XT MFM hard disk support is enabled.
  92. X86-32 X86-32, aka i386 architecture is enabled.
  93. X86-64 X86-64 architecture is enabled.
  94. More X86-64 boot options can be found in
  95. Documentation/x86_64/boot-options.txt .
  96. In addition, the following text indicates that the option:
  97. BUGS= Relates to possible processor bugs on the said processor.
  98. KNL Is a kernel start-up parameter.
  99. BOOT Is a boot loader parameter.
  100. Parameters denoted with BOOT are actually interpreted by the boot
  101. loader, and have no meaning to the kernel directly.
  102. Do not modify the syntax of boot loader parameters without extreme
  103. need or coordination with <Documentation/i386/boot.txt>.
  104. There are also arch-specific kernel-parameters not documented here.
  105. See for example <Documentation/x86_64/boot-options.txt>.
  106. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  107. a trailing = on the name of any parameter states that that parameter will
  108. be entered as an environment variable, whereas its absence indicates that
  109. it will appear as a kernel argument readable via /proc/cmdline by programs
  110. running once the system is up.
  111. The number of kernel parameters is not limited, but the length of the
  112. complete command line (parameters including spaces etc.) is limited to
  113. a fixed number of characters. This limit depends on the architecture
  114. and is between 256 and 4096 characters. It is defined in the file
  115. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  116. acpi= [HW,ACPI,X86-64,i386]
  117. Advanced Configuration and Power Interface
  118. Format: { force | off | ht | strict | noirq }
  119. force -- enable ACPI if default was off
  120. off -- disable ACPI if default was on
  121. noirq -- do not use ACPI for IRQ routing
  122. ht -- run only enough ACPI to enable Hyper Threading
  123. strict -- Be less tolerant of platforms that are not
  124. strictly ACPI specification compliant.
  125. See also Documentation/power/pm.txt, pci=noacpi
  126. acpi_apic_instance= [ACPI, IOAPIC]
  127. Format: <int>
  128. 2: use 2nd APIC table, if available
  129. 1,0: use 1st APIC table
  130. default: 0
  131. acpi_sleep= [HW,ACPI] Sleep options
  132. Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
  133. See Documentation/power/video.txt for s3_bios and s3_mode.
  134. s3_beep is for debugging; it makes the PC's speaker beep
  135. as soon as the kernel's real-mode entry point is called.
  136. s4_nohwsig prevents ACPI hardware signature from being
  137. used during resume from hibernation.
  138. old_ordering causes the ACPI 1.0 ordering of the _PTS
  139. control method, wrt putting devices into low power
  140. states, to be enforced (the ACPI 2.0 ordering of _PTS is
  141. used by default).
  142. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  143. Format: { level | edge | high | low }
  144. acpi_irq_balance [HW,ACPI]
  145. ACPI will balance active IRQs
  146. default in APIC mode
  147. acpi_irq_nobalance [HW,ACPI]
  148. ACPI will not move active IRQs (default)
  149. default in PIC mode
  150. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  151. use by PCI
  152. Format: <irq>,<irq>...
  153. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  154. Format: <irq>,<irq>...
  155. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  156. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  157. Format: To spoof as Windows 98: ="Microsoft Windows"
  158. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  159. acpi_osi="string1" # add string1 -- only one string
  160. acpi_osi="!string2" # remove built-in string2
  161. acpi_osi= # disable all strings
  162. acpi_serialize [HW,ACPI] force serialization of AML methods
  163. acpi_skip_timer_override [HW,ACPI]
  164. Recognize and ignore IRQ0/pin2 Interrupt Override.
  165. For broken nForce2 BIOS resulting in XT-PIC timer.
  166. acpi_use_timer_override [HW,ACPI}
  167. Use timer override. For some broken Nvidia NF5 boards
  168. that require a timer override, but don't have
  169. HPET
  170. acpi.debug_layer= [HW,ACPI]
  171. Format: <int>
  172. Each bit of the <int> indicates an ACPI debug layer,
  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_layer.
  176. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  177. Available bits (add the numbers together) to enable debug output
  178. for specific parts of the ACPI subsystem:
  179. 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
  180. 0x10 namespace 0x20 parser 0x40 dispatcher
  181. 0x80 executer 0x100 resources 0x200 acpica debugger
  182. 0x400 os services 0x800 acpica disassembler.
  183. The number can be in decimal or prefixed with 0x in hex.
  184. Warning: Many of these options can produce a lot of
  185. output and make your system unusable. Be very careful.
  186. acpi.debug_level= [HW,ACPI]
  187. Format: <int>
  188. Each bit of the <int> indicates an ACPI debug level,
  189. 1: enable, 0: disable. It is useful for boot time
  190. debugging. After system has booted up, it can be set
  191. via /sys/module/acpi/parameters/debug_level.
  192. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  193. Available bits (add the numbers together) to enable different
  194. debug output levels of the ACPI subsystem:
  195. 0x01 error 0x02 warn 0x04 init 0x08 debug object
  196. 0x10 info 0x20 init names 0x40 parse 0x80 load
  197. 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
  198. 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
  199. 0x10000 resources 0x20000 user requests 0x40000 package.
  200. The number can be in decimal or prefixed with 0x in hex.
  201. Warning: Many of these options can produce a lot of
  202. output and make your system unusable. Be very careful.
  203. acpi_pm_good [X86-32,X86-64]
  204. Override the pmtimer bug detection: force the kernel
  205. to assume that this machine's pmtimer latches its value
  206. and always returns good values.
  207. agp= [AGP]
  208. { off | try_unsupported }
  209. off: disable AGP support
  210. try_unsupported: try to drive unsupported chipsets
  211. (may crash computer or cause data corruption)
  212. enable_timer_pin_1 [i386,x86-64]
  213. Enable PIN 1 of APIC timer
  214. Can be useful to work around chipset bugs
  215. (in particular on some ATI chipsets).
  216. The kernel tries to set a reasonable default.
  217. disable_timer_pin_1 [i386,x86-64]
  218. Disable PIN 1 of APIC timer
  219. Can be useful to work around chipset bugs.
  220. ad1848= [HW,OSS]
  221. Format: <io>,<irq>,<dma>,<dma2>,<type>
  222. advansys= [HW,SCSI]
  223. See header of drivers/scsi/advansys.c.
  224. advwdt= [HW,WDT] Advantech WDT
  225. Format: <iostart>,<iostop>
  226. aedsp16= [HW,OSS] Audio Excel DSP 16
  227. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  228. See also header of sound/oss/aedsp16.c.
  229. aha152x= [HW,SCSI]
  230. See Documentation/scsi/aha152x.txt.
  231. aha1542= [HW,SCSI]
  232. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  233. aic7xxx= [HW,SCSI]
  234. See Documentation/scsi/aic7xxx.txt.
  235. aic79xx= [HW,SCSI]
  236. See Documentation/scsi/aic79xx.txt.
  237. amd_iommu= [HW,X86-84]
  238. Pass parameters to the AMD IOMMU driver in the system.
  239. Possible values are:
  240. isolate - enable device isolation (each device, as far
  241. as possible, will get its own protection
  242. domain)
  243. amd_iommu_size= [HW,X86-64]
  244. Define the size of the aperture for the AMD IOMMU
  245. driver. Possible values are:
  246. '32M', '64M' (default), '128M', '256M', '512M', '1G'
  247. amijoy.map= [HW,JOY] Amiga joystick support
  248. Map of devices attached to JOY0DAT and JOY1DAT
  249. Format: <a>,<b>
  250. See also Documentation/kernel/input/joystick.txt
  251. analog.map= [HW,JOY] Analog joystick and gamepad support
  252. Specifies type or capabilities of an analog joystick
  253. connected to one of 16 gameports
  254. Format: <type1>,<type2>,..<type16>
  255. apc= [HW,SPARC]
  256. Power management functions (SPARCstation-4/5 + deriv.)
  257. Format: noidle
  258. Disable APC CPU standby support. SPARCstation-Fox does
  259. not play well with APC CPU idle - disable it if you have
  260. APC and your system crashes randomly.
  261. apic= [APIC,i386] Advanced Programmable Interrupt Controller
  262. Change the output verbosity whilst booting
  263. Format: { quiet (default) | verbose | debug }
  264. Change the amount of debugging information output
  265. when initialising the APIC and IO-APIC components.
  266. apm= [APM] Advanced Power Management
  267. See header of arch/x86/kernel/apm_32.c.
  268. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  269. Format: <io>,<irq>,<nodeID>
  270. ataflop= [HW,M68k]
  271. atarimouse= [HW,MOUSE] Atari Mouse
  272. atascsi= [HW,SCSI] Atari SCSI
  273. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  274. EzKey and similar keyboards
  275. atkbd.reset= [HW] Reset keyboard during initialization
  276. atkbd.set= [HW] Select keyboard code set
  277. Format: <int> (2 = AT (default), 3 = PS/2)
  278. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  279. keyboards
  280. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  281. Format: <bool> (0 = real, 1 = synthetic (default))
  282. atkbd.softrepeat= [HW]
  283. Use software keyboard repeat
  284. autotest [IA64]
  285. baycom_epp= [HW,AX25]
  286. Format: <io>,<mode>
  287. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  288. Format: <io>,<mode>
  289. See header of drivers/net/hamradio/baycom_par.c.
  290. baycom_ser_fdx= [HW,AX25]
  291. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  292. Format: <io>,<irq>,<mode>[,<baud>]
  293. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  294. baycom_ser_hdx= [HW,AX25]
  295. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  296. Format: <io>,<irq>,<mode>
  297. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  298. boot_delay= Milliseconds to delay each printk during boot.
  299. Values larger than 10 seconds (10000) are changed to
  300. no delay (0).
  301. Format: integer
  302. bootmem_debug [KNL] Enable bootmem allocator debug messages.
  303. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  304. bttv.radio= Most important insmod options are available as
  305. kernel args too.
  306. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  307. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  308. BusLogic= [HW,SCSI]
  309. See drivers/scsi/BusLogic.c, comment before function
  310. BusLogic_ParseDriverOptions().
  311. c101= [NET] Moxa C101 synchronous serial card
  312. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  313. Sometimes CPU hardware bugs make them report the cache
  314. size incorrectly. The kernel will attempt work arounds
  315. to fix known problems, but for some CPUs it is not
  316. possible to determine what the correct size should be.
  317. This option provides an override for these situations.
  318. security= [SECURITY] Choose a security module to enable at boot.
  319. If this boot parameter is not specified, only the first
  320. security module asking for security registration will be
  321. loaded. An invalid security module name will be treated
  322. as if no module has been chosen.
  323. capability.disable=
  324. [SECURITY] Disable capabilities. This would normally
  325. be used only if an alternative security model is to be
  326. configured. Potentially dangerous and should only be
  327. used if you are entirely sure of the consequences.
  328. ccw_timeout_log [S390]
  329. See Documentation/s390/CommonIO for details.
  330. cgroup_disable= [KNL] Disable a particular controller
  331. Format: {name of the controller(s) to disable}
  332. {Currently supported controllers - "memory"}
  333. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  334. Format: { "0" | "1" }
  335. See security/selinux/Kconfig help text.
  336. 0 -- check protection applied by kernel (includes
  337. any implied execute protection).
  338. 1 -- check protection requested by application.
  339. Default value is set via a kernel config option.
  340. Value can be changed at runtime via
  341. /selinux/checkreqprot.
  342. cio_ignore= [S390]
  343. See Documentation/s390/CommonIO for details.
  344. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  345. [Deprecated]
  346. Forces specified clocksource (if available) to be used
  347. when calculating gettimeofday(). If specified
  348. clocksource is not available, it defaults to PIT.
  349. Format: { pit | tsc | cyclone | pmtmr }
  350. clocksource= [GENERIC_TIME] Override the default clocksource
  351. Format: <string>
  352. Override the default clocksource and use the clocksource
  353. with the name specified.
  354. Some clocksource names to choose from, depending on
  355. the platform:
  356. [all] jiffies (this is the base, fallback clocksource)
  357. [ACPI] acpi_pm
  358. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  359. pxa_timer,timer3,32k_counter,timer0_1
  360. [AVR32] avr32
  361. [X86-32] pit,hpet,tsc,vmi-timer;
  362. scx200_hrt on Geode; cyclone on IBM x440
  363. [MIPS] MIPS
  364. [PARISC] cr16
  365. [S390] tod
  366. [SH] SuperH
  367. [SPARC64] tick
  368. [X86-64] hpet,tsc
  369. clearcpuid=BITNUM [X86]
  370. Disable CPUID feature X for the kernel. See
  371. include/asm-x86/cpufeature.h for the valid bit numbers.
  372. Note the Linux specific bits are not necessarily
  373. stable over kernel options, but the vendor specific
  374. ones should be.
  375. Also note that user programs calling CPUID directly
  376. or using the feature without checking anything
  377. will still see it. This just prevents it from
  378. being used by the kernel or shown in /proc/cpuinfo.
  379. Also note the kernel might malfunction if you disable
  380. some critical bits.
  381. code_bytes [IA32/X86_64] How many bytes of object code to print
  382. in an oops report.
  383. Range: 0 - 8192
  384. Default: 64
  385. disable_8254_timer
  386. enable_8254_timer
  387. [IA32/X86_64] Disable/Enable interrupt 0 timer routing
  388. over the 8254 in addition to over the IO-APIC. The
  389. kernel tries to set a sensible default.
  390. hpet= [X86-32,HPET] option to control HPET usage
  391. Format: { enable (default) | disable | force }
  392. disable: disable HPET and use PIT instead
  393. force: allow force enabled of undocumented chips (ICH4,
  394. VIA, nVidia)
  395. com20020= [HW,NET] ARCnet - COM20020 chipset
  396. Format:
  397. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  398. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  399. Format: <io>[,<irq>]
  400. com90xx= [HW,NET]
  401. ARCnet - COM90xx chipset (memory-mapped buffers)
  402. Format: <io>[,<irq>[,<memstart>]]
  403. condev= [HW,S390] console device
  404. conmode=
  405. console= [KNL] Output console device and options.
  406. tty<n> Use the virtual console device <n>.
  407. ttyS<n>[,options]
  408. ttyUSB0[,options]
  409. Use the specified serial port. The options are of
  410. the form "bbbbpnf", where "bbbb" is the baud rate,
  411. "p" is parity ("n", "o", or "e"), "n" is number of
  412. bits, and "f" is flow control ("r" for RTS or
  413. omit it). Default is "9600n8".
  414. See Documentation/serial-console.txt for more
  415. information. See
  416. Documentation/networking/netconsole.txt for an
  417. alternative.
  418. uart[8250],io,<addr>[,options]
  419. uart[8250],mmio,<addr>[,options]
  420. Start an early, polled-mode console on the 8250/16550
  421. UART at the specified I/O port or MMIO address,
  422. switching to the matching ttyS device later. The
  423. options are the same as for ttyS, above.
  424. If the device connected to the port is not a TTY but a braille
  425. device, prepend "brl," before the device type, for instance
  426. console=brl,ttyS0
  427. For now, only VisioBraille is supported.
  428. earlycon= [KNL] Output early console device and options.
  429. uart[8250],io,<addr>[,options]
  430. uart[8250],mmio,<addr>[,options]
  431. Start an early, polled-mode console on the 8250/16550
  432. UART at the specified I/O port or MMIO address.
  433. The options are the same as for ttyS, above.
  434. no_console_suspend
  435. [HW] Never suspend the console
  436. Disable suspending of consoles during suspend and
  437. hibernate operations. Once disabled, debugging
  438. messages can reach various consoles while the rest
  439. of the system is being put to sleep (ie, while
  440. debugging driver suspend/resume hooks). This may
  441. not work reliably with all consoles, but is known
  442. to work with serial and VGA consoles.
  443. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  444. Format:
  445. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  446. crashkernel=nn[KMG]@ss[KMG]
  447. [KNL] Reserve a chunk of physical memory to
  448. hold a kernel to switch to with kexec on panic.
  449. crashkernel=range1:size1[,range2:size2,...][@offset]
  450. [KNL] Same as above, but depends on the memory
  451. in the running system. The syntax of range is
  452. start-[end] where start and end are both
  453. a memory unit (amount[KMG]). See also
  454. Documentation/kdump/kdump.txt for a example.
  455. cs4232= [HW,OSS]
  456. Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
  457. cs89x0_dma= [HW,NET]
  458. Format: <dma>
  459. cs89x0_media= [HW,NET]
  460. Format: { rj45 | aui | bnc }
  461. dasd= [HW,NET]
  462. See header of drivers/s390/block/dasd_devmap.c.
  463. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  464. (one device per port)
  465. Format: <port#>,<type>
  466. See also Documentation/input/joystick-parport.txt
  467. debug [KNL] Enable kernel debugging (events log level).
  468. debug_locks_verbose=
  469. [KNL] verbose self-tests
  470. Format=<0|1>
  471. Print debugging info while doing the locking API
  472. self-tests.
  473. We default to 0 (no extra messages), setting it to
  474. 1 will print _a lot_ more information - normally
  475. only useful to kernel developers.
  476. debug_objects [KNL] Enable object debugging
  477. debugpat [X86] Enable PAT debugging
  478. decnet.addr= [HW,NET]
  479. Format: <area>[,<node>]
  480. See also Documentation/networking/decnet.txt.
  481. vt.default_blu= [VT]
  482. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  483. Change the default blue palette of the console.
  484. This is a 16-member array composed of values
  485. ranging from 0-255.
  486. vt.default_grn= [VT]
  487. Format: <green0>,<green1>,<green2>,...,<green15>
  488. Change the default green palette of the console.
  489. This is a 16-member array composed of values
  490. ranging from 0-255.
  491. vt.default_red= [VT]
  492. Format: <red0>,<red1>,<red2>,...,<red15>
  493. Change the default red palette of the console.
  494. This is a 16-member array composed of values
  495. ranging from 0-255.
  496. vt.default_utf8=
  497. [VT]
  498. Format=<0|1>
  499. Set system-wide default UTF-8 mode for all tty's.
  500. Default is 1, i.e. UTF-8 mode is enabled for all
  501. newly opened terminals.
  502. dhash_entries= [KNL]
  503. Set number of hash buckets for dentry cache.
  504. digi= [HW,SERIAL]
  505. IO parameters + enable/disable command.
  506. digiepca= [HW,SERIAL]
  507. See drivers/char/README.epca and
  508. Documentation/digiepca.txt.
  509. disable_mtrr_cleanup [X86]
  510. enable_mtrr_cleanup [X86]
  511. The kernel tries to adjust MTRR layout from continuous
  512. to discrete, to make X server driver able to add WB
  513. entry later. This parameter enables/disables that.
  514. mtrr_chunk_size=nn[KMG] [X86]
  515. used for mtrr cleanup. It is largest continous chunk
  516. that could hold holes aka. UC entries.
  517. mtrr_gran_size=nn[KMG] [X86]
  518. Used for mtrr cleanup. It is granularity of mtrr block.
  519. Default is 1.
  520. Large value could prevent small alignment from
  521. using up MTRRs.
  522. mtrr_spare_reg_nr=n [X86]
  523. Format: <integer>
  524. Range: 0,7 : spare reg number
  525. Default : 1
  526. Used for mtrr cleanup. It is spare mtrr entries number.
  527. Set to 2 or more if your graphical card needs more.
  528. disable_mtrr_trim [X86, Intel and AMD only]
  529. By default the kernel will trim any uncacheable
  530. memory out of your available memory pool based on
  531. MTRR settings. This parameter disables that behavior,
  532. possibly causing your machine to run very slowly.
  533. dmasound= [HW,OSS] Sound subsystem buffers
  534. dscc4.setup= [NET]
  535. dtc3181e= [HW,SCSI]
  536. earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
  537. earlyprintk=vga
  538. earlyprintk=serial[,ttySn[,baudrate]]
  539. Append ",keep" to not disable it when the real console
  540. takes over.
  541. Only vga or serial at a time, not both.
  542. Currently only ttyS0 and ttyS1 are supported.
  543. Interaction with the standard serial driver is not
  544. very good.
  545. The VGA output is eventually overwritten by the real
  546. console.
  547. eata= [HW,SCSI]
  548. edd= [EDD]
  549. Format: {"off" | "on" | "skip[mbr]"}
  550. eisa_irq_edge= [PARISC,HW]
  551. See header of drivers/parisc/eisa.c.
  552. elanfreq= [X86-32]
  553. See comment before function elanfreq_setup() in
  554. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
  555. elevator= [IOSCHED]
  556. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  557. See Documentation/block/as-iosched.txt and
  558. Documentation/block/deadline-iosched.txt for details.
  559. elfcorehdr= [X86-32, X86_64]
  560. Specifies physical address of start of kernel core
  561. image elf header. Generally kexec loader will
  562. pass this option to capture kernel.
  563. See Documentation/kdump/kdump.txt for details.
  564. enforcing [SELINUX] Set initial enforcing status.
  565. Format: {"0" | "1"}
  566. See security/selinux/Kconfig help text.
  567. 0 -- permissive (log only, no denials).
  568. 1 -- enforcing (deny and log).
  569. Default value is 0.
  570. Value can be changed at runtime via /selinux/enforce.
  571. es1371= [HW,OSS]
  572. Format: <spdif>,[<nomix>,[<amplifier>]]
  573. See also header of sound/oss/es1371.c.
  574. ether= [HW,NET] Ethernet cards parameters
  575. This option is obsoleted by the "netdev=" option, which
  576. has equivalent usage. See its documentation for details.
  577. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  578. Format: <io>[,<irq>]
  579. failslab=
  580. fail_page_alloc=
  581. fail_make_request=[KNL]
  582. General fault injection mechanism.
  583. Format: <interval>,<probability>,<space>,<times>
  584. See also /Documentation/fault-injection/.
  585. fd_mcs= [HW,SCSI]
  586. See header of drivers/scsi/fd_mcs.c.
  587. fdomain= [HW,SCSI]
  588. See header of drivers/scsi/fdomain.c.
  589. floppy= [HW]
  590. See Documentation/floppy.txt.
  591. force_pal_cache_flush
  592. [IA-64] Avoid check_sal_cache_flush which may hang on
  593. buggy SAL_CACHE_FLUSH implementations. Using this
  594. parameter will force ia64_sal_cache_flush to call
  595. ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
  596. gamecon.map[2|3]=
  597. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  598. support via parallel port (up to 5 devices per port)
  599. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  600. See also Documentation/input/joystick-parport.txt
  601. gamma= [HW,DRM]
  602. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  603. Format: off | on
  604. default: on
  605. gdth= [HW,SCSI]
  606. See header of drivers/scsi/gdth.c.
  607. gpt [EFI] Forces disk with valid GPT signature but
  608. invalid Protective MBR to be treated as GPT.
  609. gvp11= [HW,SCSI]
  610. hashdist= [KNL,NUMA] Large hashes allocated during boot
  611. are distributed across NUMA nodes. Defaults on
  612. for IA-64, off otherwise.
  613. Format: 0 | 1 (for off | on)
  614. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  615. hd= [EIDE] (E)IDE hard drive subsystem geometry
  616. Format: <cyl>,<head>,<sect>
  617. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  618. size of <nn>. This works even on boxes that have no
  619. highmem otherwise. This also works to reduce highmem
  620. size on bigger boxes.
  621. highres= [KNL] Enable/disable high resolution timer mode.
  622. Valid parameters: "on", "off"
  623. Default: "on"
  624. hisax= [HW,ISDN]
  625. See Documentation/isdn/README.HiSax.
  626. hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
  627. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
  628. On x86-64 and powerpc, this option can be specified
  629. multiple times interleaved with hugepages= to reserve
  630. huge pages of different sizes. Valid pages sizes on
  631. x86-64 are 2M (when the CPU supports "pse") and 1G
  632. (when the CPU supports the "pdpe1gb" cpuinfo flag)
  633. Note that 1GB pages can only be allocated at boot time
  634. using hugepages= and not freed afterwards.
  635. default_hugepagesz=
  636. [same as hugepagesz=] The size of the default
  637. HugeTLB page size. This is the size represented by
  638. the legacy /proc/ hugepages APIs, used for SHM, and
  639. default size when mounting hugetlbfs filesystems.
  640. Defaults to the default architecture's huge page size
  641. if not specified.
  642. i8042.direct [HW] Put keyboard port into non-translated mode
  643. i8042.dumbkbd [HW] Pretend that controller can only read data from
  644. keyboard and cannot control its state
  645. (Don't attempt to blink the leds)
  646. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  647. i8042.nokbd [HW] Don't check/create keyboard port
  648. i8042.noloop [HW] Disable the AUX Loopback command while probing
  649. for the AUX port
  650. i8042.nomux [HW] Don't check presence of an active multiplexing
  651. controller
  652. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  653. controllers
  654. i8042.panicblink=
  655. [HW] Frequency with which keyboard LEDs should blink
  656. when kernel panics (default is 0.5 sec)
  657. i8042.reset [HW] Reset the controller during init and cleanup
  658. i8042.unlock [HW] Unlock (ignore) the keylock
  659. i810= [HW,DRM]
  660. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  661. indicates that the driver is running on unsupported
  662. hardware.
  663. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  664. does not match list of supported models.
  665. i8k.power_status
  666. [HW] Report power status in /proc/i8k
  667. (disabled by default)
  668. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  669. capability is set.
  670. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  671. See Documentation/mca.txt.
  672. icn= [HW,ISDN]
  673. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  674. ide= [HW] (E)IDE subsystem
  675. Format: ide=nodma or ide=doubler
  676. See Documentation/ide/ide.txt.
  677. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  678. See Documentation/ide/ide.txt.
  679. idle= [X86]
  680. Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
  681. Poll forces a polling idle loop that can slightly improves the performance
  682. of waking up a idle CPU, but will use a lot of power and make the system
  683. run hot. Not recommended.
  684. idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
  685. to not use it because it doesn't save as much power as a normal idle
  686. loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
  687. as idle=poll.
  688. idle=halt. Halt is forced to be used for CPU idle.
  689. In such case C2/C3 won't be used again.
  690. idle=nomwait. Disable mwait for CPU C-states
  691. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  692. Claim all unknown PCI IDE storage controllers.
  693. ignore_loglevel [KNL]
  694. Ignore loglevel setting - this will print /all/
  695. kernel messages to the console. Useful for debugging.
  696. ihash_entries= [KNL]
  697. Set number of hash buckets for inode cache.
  698. in2000= [HW,SCSI]
  699. See header of drivers/scsi/in2000.c.
  700. init= [KNL]
  701. Format: <full_path>
  702. Run specified binary instead of /sbin/init as init
  703. process.
  704. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  705. for working out where the kernel is dying during
  706. startup.
  707. initrd= [BOOT] Specify the location of the initial ramdisk
  708. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  709. Format: <irq>
  710. inttest= [IA64]
  711. iommu= [x86]
  712. off
  713. force
  714. noforce
  715. biomerge
  716. panic
  717. nopanic
  718. merge
  719. nomerge
  720. forcesac
  721. soft
  722. fullflush
  723. Flush IO/TLB at every deallocation
  724. nofullflush
  725. Flush IO/TLB only when addresses are reused (default)
  726. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  727. off
  728. Disable intel iommu driver.
  729. igfx_off [Default Off]
  730. By default, gfx is mapped as normal device. If a gfx
  731. device has a dedicated DMAR unit, the DMAR unit is
  732. bypassed by not enabling DMAR with this option. In
  733. this case, gfx device will use physical address for
  734. DMA.
  735. forcedac [x86_64]
  736. With this option iommu will not optimize to look
  737. for io virtual address below 32 bit forcing dual
  738. address cycle on pci bus for cards supporting greater
  739. than 32 bit addressing. The default is to look
  740. for translation below 32 bit and if not available
  741. then look in the higher range.
  742. strict [Default Off]
  743. With this option on every unmap_single operation will
  744. result in a hardware IOTLB flush operation as opposed
  745. to batching them for performance.
  746. io_delay= [X86-32,X86-64] I/O delay method
  747. 0x80
  748. Standard port 0x80 based delay
  749. 0xed
  750. Alternate port 0xed based delay (needed on some systems)
  751. udelay
  752. Simple two microseconds delay
  753. none
  754. No delay
  755. io7= [HW] IO7 for Marvel based alpha systems
  756. See comment before marvel_specify_io7 in
  757. arch/alpha/kernel/core_marvel.c.
  758. ip= [IP_PNP]
  759. See Documentation/filesystems/nfsroot.txt.
  760. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  761. See comment before ip2_setup() in
  762. drivers/char/ip2/ip2base.c.
  763. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  764. See header of drivers/scsi/ips.c.
  765. ports= [IP_VS_FTP] IPVS ftp helper module
  766. Default is 21.
  767. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  768. may be specified.
  769. Format: <port>,<port>....
  770. irqfixup [HW]
  771. When an interrupt is not handled search all handlers
  772. for it. Intended to get systems with badly broken
  773. firmware running.
  774. irqpoll [HW]
  775. When an interrupt is not handled search all handlers
  776. for it. Also check all handlers each timer
  777. interrupt. Intended to get systems with badly broken
  778. firmware running.
  779. isapnp= [ISAPNP]
  780. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  781. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  782. Format:
  783. <cpu number>,...,<cpu number>
  784. or
  785. <cpu number>-<cpu number> (must be a positive range in ascending order)
  786. or a mixture
  787. <cpu number>,...,<cpu number>-<cpu number>
  788. This option can be used to specify one or more CPUs
  789. to isolate from the general SMP balancing and scheduling
  790. algorithms. The only way to move a process onto or off
  791. an "isolated" CPU is via the CPU affinity syscalls.
  792. <cpu number> begins at 0 and the maximum value is
  793. "number of CPUs in system - 1".
  794. This option is the preferred way to isolate CPUs. The
  795. alternative -- manually setting the CPU mask of all
  796. tasks in the system -- can cause problems and
  797. suboptimal load balancer performance.
  798. iucv= [HW,NET]
  799. js= [HW,JOY] Analog joystick
  800. See Documentation/input/joystick.txt.
  801. kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  802. specifies the amount of memory usable by the kernel
  803. for non-movable allocations. The requested amount is
  804. spread evenly throughout all nodes in the system. The
  805. remaining memory in each node is used for Movable
  806. pages. In the event, a node is too small to have both
  807. kernelcore and Movable pages, kernelcore pages will
  808. take priority and other nodes will have a larger number
  809. of kernelcore pages. The Movable zone is used for the
  810. allocation of pages that may be reclaimed or moved
  811. by the page migration subsystem. This means that
  812. HugeTLB pages may not be allocated from this zone.
  813. Note that allocations like PTEs-from-HighMem still
  814. use the HighMem zone if it exists, and the Normal
  815. zone if it does not.
  816. movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  817. is similar to kernelcore except it specifies the
  818. amount of memory used for migratable allocations.
  819. If both kernelcore and movablecore is specified,
  820. then kernelcore will be at *least* the specified
  821. value but may be more. If movablecore on its own
  822. is specified, the administrator must be careful
  823. that the amount of memory usable for all allocations
  824. is not too small.
  825. keepinitrd [HW,ARM]
  826. kstack=N [X86-32,X86-64] Print N words from the kernel stack
  827. in oops dumps.
  828. kgdboc= [HW] kgdb over consoles.
  829. Requires a tty driver that supports console polling.
  830. (only serial suported for now)
  831. Format: <serial_device>[,baud]
  832. l2cr= [PPC]
  833. l3cr= [PPC]
  834. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  835. disabled it.
  836. lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
  837. C2 power state.
  838. libata.dma= [LIBATA] DMA control
  839. libata.dma=0 Disable all PATA and SATA DMA
  840. libata.dma=1 PATA and SATA Disk DMA only
  841. libata.dma=2 ATAPI (CDROM) DMA only
  842. libata.dma=4 Compact Flash DMA only
  843. Combinations also work, so libata.dma=3 enables DMA
  844. for disks and CDROMs, but not CFs.
  845. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  846. when set.
  847. Format: <int>
  848. libata.force= [LIBATA] Force configurations. The format is comma
  849. separated list of "[ID:]VAL" where ID is
  850. PORT[:DEVICE]. PORT and DEVICE are decimal numbers
  851. matching port, link or device. Basically, it matches
  852. the ATA ID string printed on console by libata. If
  853. the whole ID part is omitted, the last PORT and DEVICE
  854. values are used. If ID hasn't been specified yet, the
  855. configuration applies to all ports, links and devices.
  856. If only DEVICE is omitted, the parameter applies to
  857. the port and all links and devices behind it. DEVICE
  858. number of 0 either selects the first device or the
  859. first fan-out link behind PMP device. It does not
  860. select the host link. DEVICE number of 15 selects the
  861. host link and device attached to it.
  862. The VAL specifies the configuration to force. As long
  863. as there's no ambiguity shortcut notation is allowed.
  864. For example, both 1.5 and 1.5G would work for 1.5Gbps.
  865. The following configurations can be forced.
  866. * Cable type: 40c, 80c, short40c, unk, ign or sata.
  867. Any ID with matching PORT is used.
  868. * SATA link speed limit: 1.5Gbps or 3.0Gbps.
  869. * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
  870. udma[/][16,25,33,44,66,100,133] notation is also
  871. allowed.
  872. * [no]ncq: Turn on or off NCQ.
  873. * nohrst, nosrst, norst: suppress hard, soft
  874. and both resets.
  875. If there are multiple matching configurations changing
  876. the same attribute, the last one is used.
  877. load_ramdisk= [RAM] List of ramdisks to load from floppy
  878. See Documentation/ramdisk.txt.
  879. lockd.nlm_grace_period=P [NFS] Assign grace period.
  880. Format: <integer>
  881. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  882. Format: <integer>
  883. lockd.nlm_timeout=T [NFS] Assign timeout value.
  884. Format: <integer>
  885. lockd.nlm_udpport=M [NFS] Assign UDP port.
  886. Format: <integer>
  887. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  888. Format: <irq>
  889. loglevel= All Kernel Messages with a loglevel smaller than the
  890. console loglevel will be printed to the console. It can
  891. also be changed with klogd or other programs. The
  892. loglevels are defined as follows:
  893. 0 (KERN_EMERG) system is unusable
  894. 1 (KERN_ALERT) action must be taken immediately
  895. 2 (KERN_CRIT) critical conditions
  896. 3 (KERN_ERR) error conditions
  897. 4 (KERN_WARNING) warning conditions
  898. 5 (KERN_NOTICE) normal but significant condition
  899. 6 (KERN_INFO) informational
  900. 7 (KERN_DEBUG) debug-level messages
  901. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  902. Format: { n | nk | nM }
  903. n must be a power of two. The default size
  904. is set in the kernel config file.
  905. logo.nologo [FB] Disables display of the built-in Linux logo.
  906. This may be used to provide more screen space for
  907. kernel log messages and is useful when debugging
  908. kernel boot problems.
  909. lp=0 [LP] Specify parallel ports to use, e.g,
  910. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  911. lp=reset first parallel port). 'lp=0' disables the
  912. lp=auto printer driver. 'lp=reset' (which can be
  913. specified in addition to the ports) causes
  914. attached printers to be reset. Using
  915. lp=port1,port2,... specifies the parallel ports
  916. to associate lp devices with, starting with
  917. lp0. A port specification may be 'none' to skip
  918. that lp device, or a parport name such as
  919. 'parport0'. Specifying 'lp=auto' instead of a
  920. port specification list means that device IDs
  921. from each port should be examined, to see if
  922. an IEEE 1284-compliant printer is attached; if
  923. so, the driver will manage that printer.
  924. See also header of drivers/char/lp.c.
  925. lpj=n [KNL]
  926. Sets loops_per_jiffy to given constant, thus avoiding
  927. time-consuming boot-time autodetection (up to 250 ms per
  928. CPU). 0 enables autodetection (default). To determine
  929. the correct value for your kernel, boot with normal
  930. autodetection and see what value is printed. Note that
  931. on SMP systems the preset will be applied to all CPUs,
  932. which is likely to cause problems if your CPUs need
  933. significantly divergent settings. An incorrect value
  934. will cause delays in the kernel to be wrong, leading to
  935. unpredictable I/O errors and other breakage. Although
  936. unlikely, in the extreme case this might damage your
  937. hardware.
  938. ltpc= [NET]
  939. Format: <io>,<irq>,<dma>
  940. mac5380= [HW,SCSI] Format:
  941. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  942. machvec= [IA64] Force the use of a particular machine-vector
  943. (machvec) in a generic kernel.
  944. Example: machvec=hpzx1_swiotlb
  945. max_loop= [LOOP] Maximum number of loopback devices that can
  946. be mounted
  947. Format: <1-256>
  948. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  949. should make use of. maxcpus=n : n >= 0 limits the
  950. kernel to using 'n' processors. n=0 is a special case,
  951. it is equivalent to "nosmp", which also disables
  952. the IO APIC.
  953. max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
  954. equal to this physical address is ignored.
  955. max_luns= [SCSI] Maximum number of LUNs to probe.
  956. Should be between 1 and 2^32-1.
  957. max_report_luns=
  958. [SCSI] Maximum number of LUNs received.
  959. Should be between 1 and 16384.
  960. mcatest= [IA-64]
  961. mce [X86-32] Machine Check Exception
  962. mce=option [X86-64] See Documentation/x86_64/boot-options.txt
  963. md= [HW] RAID subsystems devices and level
  964. See Documentation/md.txt.
  965. mdacon= [MDA]
  966. Format: <first>,<last>
  967. Specifies range of consoles to be captured by the MDA.
  968. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  969. Amount of memory to be used when the kernel is not able
  970. to see the whole system memory or for test.
  971. [X86-32] Use together with memmap= to avoid physical
  972. address space collisions. Without memmap= PCI devices
  973. could be placed at addresses belonging to unused RAM.
  974. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  975. memory.
  976. memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
  977. E820 memory map, as specified by the user.
  978. Such memmap=exactmap lines can be constructed based on
  979. BIOS output or other requirements. See the memmap=nn@ss
  980. option description.
  981. memmap=nn[KMG]@ss[KMG]
  982. [KNL] Force usage of a specific region of memory
  983. Region of memory to be used, from ss to ss+nn.
  984. memmap=nn[KMG]#ss[KMG]
  985. [KNL,ACPI] Mark specific memory as ACPI data.
  986. Region of memory to be used, from ss to ss+nn.
  987. memmap=nn[KMG]$ss[KMG]
  988. [KNL,ACPI] Mark specific memory as reserved.
  989. Region of memory to be used, from ss to ss+nn.
  990. Example: Exclude memory from 0x18690000-0x1869ffff
  991. memmap=64K$0x18690000
  992. or
  993. memmap=0x10000$0x18690000
  994. memtest= [KNL,X86] Enable memtest
  995. Format: <integer>
  996. range: 0,4 : pattern number
  997. default : 0 <disable>
  998. meye.*= [HW] Set MotionEye Camera parameters
  999. See Documentation/video4linux/meye.txt.
  1000. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  1001. Multi-Function General Purpose Timers on AMD Geode
  1002. platforms.
  1003. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  1004. the BIOS has incorrectly applied a workaround. TinyBIOS
  1005. version 0.98 is known to be affected, 0.99 fixes the
  1006. problem by letting the user disable the workaround.
  1007. mga= [HW,DRM]
  1008. mminit_loglevel=
  1009. [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
  1010. parameter allows control of the logging verbosity for
  1011. the additional memory initialisation checks. A value
  1012. of 0 disables mminit logging and a level of 4 will
  1013. log everything. Information is printed at KERN_DEBUG
  1014. so loglevel=8 may also need to be specified.
  1015. mousedev.tap_time=
  1016. [MOUSE] Maximum time between finger touching and
  1017. leaving touchpad surface for touch to be considered
  1018. a tap and be reported as a left button click (for
  1019. touchpads working in absolute mode only).
  1020. Format: <msecs>
  1021. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  1022. reporting absolute coordinates, such as tablets
  1023. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  1024. reporting absolute coordinates, such as tablets
  1025. mpu401= [HW,OSS]
  1026. Format: <io>,<irq>
  1027. MTD_Partition= [MTD]
  1028. Format: <name>,<region-number>,<size>,<offset>
  1029. MTD_Region= [MTD] Format:
  1030. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  1031. mtdparts= [MTD]
  1032. See drivers/mtd/cmdlinepart.c.
  1033. mtdset= [ARM]
  1034. ARM/S3C2412 JIVE boot control
  1035. See arch/arm/mach-s3c2412/mach-jive.c
  1036. mtouchusb.raw_coordinates=
  1037. [HW] Make the MicroTouch USB driver use raw coordinates
  1038. ('y', default) or cooked coordinates ('n')
  1039. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  1040. NCR_D700= [HW,SCSI]
  1041. See header of drivers/scsi/NCR_D700.c.
  1042. ncr5380= [HW,SCSI]
  1043. ncr53c400= [HW,SCSI]
  1044. ncr53c400a= [HW,SCSI]
  1045. ncr53c406a= [HW,SCSI]
  1046. ncr53c8xx= [HW,SCSI]
  1047. netdev= [NET] Network devices parameters
  1048. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  1049. Note that mem_start is often overloaded to mean
  1050. something different and driver-specific.
  1051. This usage is only documented in each driver source
  1052. file if at all.
  1053. nf_conntrack.acct=
  1054. [NETFILTER] Enable connection tracking flow accounting
  1055. 0 to disable accounting
  1056. 1 to enable accounting
  1057. Default value depends on CONFIG_NF_CT_ACCT that is
  1058. going to be removed in 2.6.29.
  1059. nfsaddrs= [NFS]
  1060. See Documentation/filesystems/nfsroot.txt.
  1061. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  1062. See Documentation/filesystems/nfsroot.txt.
  1063. nfs.callback_tcpport=
  1064. [NFS] set the TCP port on which the NFSv4 callback
  1065. channel should listen.
  1066. nfs.idmap_cache_timeout=
  1067. [NFS] set the maximum lifetime for idmapper cache
  1068. entries.
  1069. nfs.enable_ino64=
  1070. [NFS] enable 64-bit inode numbers.
  1071. If zero, the NFS client will fake up a 32-bit inode
  1072. number for the readdir() and stat() syscalls instead
  1073. of returning the full 64-bit number.
  1074. The default is to return 64-bit inode numbers.
  1075. nmi_debug= [KNL,AVR32] Specify one or more actions to take
  1076. when a NMI is triggered.
  1077. Format: [state][,regs][,debounce][,die]
  1078. nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
  1079. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  1080. emulation library even if a 387 maths coprocessor
  1081. is present.
  1082. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  1083. caches in the slab allocator. Saves per-node memory,
  1084. but will impact performance.
  1085. noalign [KNL,ARM]
  1086. noapic [SMP,APIC] Tells the kernel to not make use of any
  1087. IOAPICs that may be present in the system.
  1088. nobats [PPC] Do not use BATs for mapping kernel lowmem
  1089. on "Classic" PPC cores.
  1090. nocache [ARM]
  1091. nodelayacct [KNL] Disable per-task delay accounting
  1092. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  1093. noefi [X86-32,X86-64] Disable EFI runtime services support.
  1094. noexec [IA-64]
  1095. noexec [X86-32,X86-64]
  1096. On X86-32 available only on PAE configured kernels.
  1097. noexec=on: enable non-executable mappings (default)
  1098. noexec=off: disable non-executable mappings
  1099. noexec32 [X86-64]
  1100. This affects only 32-bit executables.
  1101. noexec32=on: enable non-executable mappings (default)
  1102. read doesn't imply executable mappings
  1103. noexec32=off: disable non-executable mappings
  1104. read implies executable mappings
  1105. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  1106. register save and restore. The kernel will only save
  1107. legacy floating-point registers on task switch.
  1108. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  1109. nohlt [BUGS=ARM]
  1110. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  1111. instruction doesn't work correctly and not to
  1112. use it.
  1113. nohalt [IA-64] Tells the kernel not to use the power saving
  1114. function PAL_HALT_LIGHT when idle. This increases
  1115. power-consumption. On the positive side, it reduces
  1116. interrupt wake-up latency, which may improve performance
  1117. in certain environments such as networked servers or
  1118. real-time systems.
  1119. nohz= [KNL] Boottime enable/disable dynamic ticks
  1120. Valid arguments: on, off
  1121. Default: on
  1122. noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
  1123. noirqdebug [X86-32] Disables the code which attempts to detect and
  1124. disable unhandled interrupt sources.
  1125. no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
  1126. broken timer IRQ sources.
  1127. noisapnp [ISAPNP] Disables ISA PnP code.
  1128. noinitrd [RAM] Tells the kernel not to load any configured
  1129. initial RAM disk.
  1130. nointroute [IA-64]
  1131. nojitter [IA64] Disables jitter checking for ITC timers.
  1132. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  1133. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  1134. noltlbs [PPC] Do not use large page/tlb entries for kernel
  1135. lowmem mapping on PPC40x.
  1136. nomca [IA-64] Disable machine check abort handling
  1137. nomce [X86-32] Machine Check Exception
  1138. nomfgpt [X86-32] Disable Multi-Function General Purpose
  1139. Timer usage (for AMD Geode machines).
  1140. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  1141. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1142. with UP alternatives
  1143. noresidual [PPC] Don't use residual data on PReP machines.
  1144. noresume [SWSUSP] Disables resume and restores original swap
  1145. space.
  1146. no-scroll [VGA] Disables scrollback.
  1147. This is required for the Braillex ib80-piezo Braille
  1148. reader made by F.H. Papenmeier (Germany).
  1149. nosbagart [IA-64]
  1150. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1151. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1152. and disable the IO APIC. legacy for "maxcpus=0".
  1153. nosoftlockup [KNL] Disable the soft-lockup detector.
  1154. nosync [HW,M68K] Disables sync negotiation for all devices.
  1155. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1156. nousb [USB] Disable the USB subsystem
  1157. nowb [ARM]
  1158. nptcg= [IA64] Override max number of concurrent global TLB
  1159. purges which is reported from either PAL_VM_SUMMARY or
  1160. SAL PALO.
  1161. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1162. one of ['zone', 'node', 'default'] can be specified
  1163. This can be set from sysctl after boot.
  1164. See Documentation/sysctl/vm.txt for details.
  1165. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1166. olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
  1167. Rather than timing out after 20 ms if an EC
  1168. command is not properly ACKed, override the length
  1169. of the timeout. We have interrupts disabled while
  1170. waiting for the ACK, so if this is set too high
  1171. interrupts *may* be lost!
  1172. opl3= [HW,OSS]
  1173. Format: <io>
  1174. oprofile.timer= [HW]
  1175. Use timer interrupt instead of performance counters
  1176. osst= [HW,SCSI] SCSI Tape Driver
  1177. Format: <buffer_size>,<write_threshold>
  1178. See also Documentation/scsi/st.txt.
  1179. panic= [KNL] Kernel behaviour on panic
  1180. Format: <timeout>
  1181. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1182. connected to, default is 0.
  1183. Format: <parport#>
  1184. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1185. 0 for XT, 1 for AT (default is AT).
  1186. Format: <mode>
  1187. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1188. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1189. Use 'auto' to force the driver to use any
  1190. IRQ/DMA settings detected (the default is to
  1191. ignore detected IRQ/DMA settings because of
  1192. possible conflicts). You can specify the base
  1193. address, IRQ, and DMA settings; IRQ and DMA
  1194. should be numbers, or 'auto' (for using detected
  1195. settings on that particular port), or 'nofifo'
  1196. (to avoid using a FIFO even if it is detected).
  1197. Parallel ports are assigned in the order they
  1198. are specified on the command line, starting
  1199. with parport0.
  1200. parport_init_mode= [HW,PPT]
  1201. Configure VIA parallel port to operate in
  1202. a specific mode. This is necessary on Pegasos
  1203. computer where firmware has no options for setting
  1204. up parallel port mode and sets it to spp.
  1205. Currently this function knows 686a and 8231 chips.
  1206. Format: [spp|ps2|epp|ecp|ecpepp]
  1207. pas2= [HW,OSS] Format:
  1208. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1209. pas16= [HW,SCSI]
  1210. See header of drivers/scsi/pas16.c.
  1211. pause_on_oops=
  1212. Halt all CPUs after the first oops has been printed for
  1213. the specified number of seconds. This is to be used if
  1214. your oopses keep scrolling off the screen.
  1215. pcbit= [HW,ISDN]
  1216. pcd. [PARIDE]
  1217. See header of drivers/block/paride/pcd.c.
  1218. See also Documentation/paride.txt.
  1219. pci=option[,option...] [PCI] various PCI subsystem options:
  1220. off [X86-32] don't probe for the PCI bus
  1221. bios [X86-32] force use of PCI BIOS, don't access
  1222. the hardware directly. Use this if your machine
  1223. has a non-standard PCI host bridge.
  1224. nobios [X86-32] disallow use of PCI BIOS, only direct
  1225. hardware access methods are allowed. Use this
  1226. if you experience crashes upon bootup and you
  1227. suspect they are caused by the BIOS.
  1228. conf1 [X86-32] Force use of PCI Configuration
  1229. Mechanism 1.
  1230. conf2 [X86-32] Force use of PCI Configuration
  1231. Mechanism 2.
  1232. noaer [PCIE] If the PCIEAER kernel config parameter is
  1233. enabled, this kernel boot option can be used to
  1234. disable the use of PCIE advanced error reporting.
  1235. nodomains [PCI] Disable support for multiple PCI
  1236. root domains (aka PCI segments, in ACPI-speak).
  1237. nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
  1238. Configuration
  1239. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1240. enabled, this kernel boot option can be used to
  1241. disable the use of MSI interrupts system-wide.
  1242. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1243. routing table. These calls are known to be buggy
  1244. on several machines and they hang the machine
  1245. when used, but on other computers it's the only
  1246. way to get the interrupt routing table. Try
  1247. this option if the kernel is unable to allocate
  1248. IRQs or discover secondary PCI buses on your
  1249. motherboard.
  1250. rom [X86-32] Assign address space to expansion ROMs.
  1251. Use with caution as certain devices share
  1252. address decoders between ROMs and other
  1253. resources.
  1254. norom [X86-32,X86_64] Do not assign address space to
  1255. expansion ROMs that do not already have
  1256. BIOS assigned address ranges.
  1257. irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
  1258. assigned automatically to PCI devices. You can
  1259. make the kernel exclude IRQs of your ISA cards
  1260. this way.
  1261. pirqaddr=0xAAAAA [X86-32] Specify the physical address
  1262. of the PIRQ table (normally generated
  1263. by the BIOS) if it is outside the
  1264. F0000h-100000h range.
  1265. lastbus=N [X86-32] Scan all buses thru bus #N. Can be
  1266. useful if the kernel is unable to find your
  1267. secondary buses and you want to tell it
  1268. explicitly which ones they are.
  1269. assign-busses [X86-32] Always assign all PCI bus
  1270. numbers ourselves, overriding
  1271. whatever the firmware may have done.
  1272. usepirqmask [X86-32] Honor the possible IRQ mask stored
  1273. in the BIOS $PIR table. This is needed on
  1274. some systems with broken BIOSes, notably
  1275. some HP Pavilion N5400 and Omnibook XE3
  1276. notebooks. This will have no effect if ACPI
  1277. IRQ routing is enabled.
  1278. noacpi [X86-32] Do not use ACPI for IRQ routing
  1279. or for PCI scanning.
  1280. use_crs [X86-32] Use _CRS for PCI resource
  1281. allocation.
  1282. routeirq Do IRQ routing for all PCI devices.
  1283. This is normally done in pci_enable_device(),
  1284. so this option is a temporary workaround
  1285. for broken drivers that don't call it.
  1286. skip_isa_align [X86] do not align io start addr, so can
  1287. handle more pci cards
  1288. firmware [ARM] Do not re-enumerate the bus but instead
  1289. just use the configuration from the
  1290. bootloader. This is currently used on
  1291. IXP2000 systems where the bus has to be
  1292. configured a certain way for adjunct CPUs.
  1293. noearly [X86] Don't do any early type 1 scanning.
  1294. This might help on some broken boards which
  1295. machine check when some devices' config space
  1296. is read. But various workarounds are disabled
  1297. and some IOMMU drivers will not work.
  1298. bfsort Sort PCI devices into breadth-first order.
  1299. This sorting is done to get a device
  1300. order compatible with older (<= 2.4) kernels.
  1301. nobfsort Don't sort PCI devices into breadth-first order.
  1302. cbiosize=nn[KMG] The fixed amount of bus space which is
  1303. reserved for the CardBus bridge's IO window.
  1304. The default value is 256 bytes.
  1305. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1306. reserved for the CardBus bridge's memory
  1307. window. The default value is 64 megabytes.
  1308. pcmv= [HW,PCMCIA] BadgePAD 4
  1309. pd. [PARIDE]
  1310. See Documentation/paride.txt.
  1311. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1312. boot time.
  1313. Format: { 0 | 1 }
  1314. See arch/parisc/kernel/pdc_chassis.c
  1315. pf. [PARIDE]
  1316. See Documentation/paride.txt.
  1317. pg. [PARIDE]
  1318. See Documentation/paride.txt.
  1319. pirq= [SMP,APIC] Manual mp-table setup
  1320. See Documentation/i386/IO-APIC.txt.
  1321. plip= [PPT,NET] Parallel port network link
  1322. Format: { parport<nr> | timid | 0 }
  1323. See also Documentation/parport.txt.
  1324. pmtmr= [X86] Manual setup of pmtmr I/O Port.
  1325. Override pmtimer IOPort with a hex value.
  1326. e.g. pmtmr=0x508
  1327. pnpacpi= [ACPI]
  1328. { off }
  1329. pnpbios= [ISAPNP]
  1330. { on | off | curr | res | no-curr | no-res }
  1331. pnp_reserve_irq=
  1332. [ISAPNP] Exclude IRQs for the autoconfiguration
  1333. pnp_reserve_dma=
  1334. [ISAPNP] Exclude DMAs for the autoconfiguration
  1335. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1336. Ranges are in pairs (I/O port base and size).
  1337. pnp_reserve_mem=
  1338. [ISAPNP] Exclude memory regions for the
  1339. autoconfiguration.
  1340. Ranges are in pairs (memory base and size).
  1341. print-fatal-signals=
  1342. [KNL] debug: print fatal signals
  1343. print-fatal-signals=1: print segfault info to
  1344. the kernel console.
  1345. default: off.
  1346. printk.time= Show timing data prefixed to each printk message line
  1347. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1348. profile= [KNL] Enable kernel profiling via /proc/profile
  1349. Format: [schedule,]<number>
  1350. Param: "schedule" - profile schedule points.
  1351. Param: <number> - step/bucket size as a power of 2 for
  1352. statistical time based profiling.
  1353. Param: "sleep" - profile D-state sleeping (millisecs).
  1354. Requires CONFIG_SCHEDSTATS
  1355. Param: "kvm" - profile VM exits.
  1356. processor.max_cstate= [HW,ACPI]
  1357. Limit processor to maximum C-state
  1358. max_cstate=9 overrides any DMI blacklist limit.
  1359. processor.nocst [HW,ACPI]
  1360. Ignore the _CST method to determine C-states,
  1361. instead using the legacy FADT method
  1362. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1363. before loading.
  1364. See Documentation/ramdisk.txt.
  1365. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1366. probe for; one of (bare|imps|exps|lifebook|any).
  1367. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1368. per second.
  1369. psmouse.resetafter= [HW,MOUSE]
  1370. Try to reset the device after so many bad packets
  1371. (0 = never).
  1372. psmouse.resolution=
  1373. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1374. psmouse.smartscroll=
  1375. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1376. 0 = disabled, 1 = enabled (default).
  1377. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1378. Format:
  1379. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1380. pt. [PARIDE]
  1381. See Documentation/paride.txt.
  1382. pty.legacy_count=
  1383. [KNL] Number of legacy pty's. Overwrites compiled-in
  1384. default number.
  1385. quiet [KNL] Disable most log messages
  1386. r128= [HW,DRM]
  1387. raid= [HW,RAID]
  1388. See Documentation/md.txt.
  1389. ramdisk_blocksize= [RAM]
  1390. See Documentation/ramdisk.txt.
  1391. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1392. See Documentation/ramdisk.txt.
  1393. rcupdate.blimit= [KNL,BOOT]
  1394. Set maximum number of finished RCU callbacks to process
  1395. in one batch.
  1396. rcupdate.qhimark= [KNL,BOOT]
  1397. Set threshold of queued
  1398. RCU callbacks over which batch limiting is disabled.
  1399. rcupdate.qlowmark= [KNL,BOOT]
  1400. Set threshold of queued RCU callbacks below which
  1401. batch limiting is re-enabled.
  1402. rdinit= [KNL]
  1403. Format: <full_path>
  1404. Run specified binary instead of /init from the ramdisk,
  1405. used for early userspace startup. See initrd.
  1406. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1407. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1408. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1409. relax_domain_level=
  1410. [KNL, SMP] Set scheduler's default relax_domain_level.
  1411. See Documentation/cpusets.txt.
  1412. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1413. reservetop= [X86-32]
  1414. Format: nn[KMG]
  1415. Reserves a hole at the top of the kernel virtual
  1416. address space.
  1417. reset_devices [KNL] Force drivers to reset the underlying device
  1418. during initialization.
  1419. resume= [SWSUSP]
  1420. Specify the partition device for software suspend
  1421. resume_offset= [SWSUSP]
  1422. Specify the offset from the beginning of the partition
  1423. given by "resume=" at which the swap header is located,
  1424. in <PAGE_SIZE> units (needed only for swap files).
  1425. See Documentation/power/swsusp-and-swap-files.txt
  1426. retain_initrd [RAM] Keep initrd memory after extraction
  1427. rhash_entries= [KNL,NET]
  1428. Set number of hash buckets for route cache
  1429. riscom8= [HW,SERIAL]
  1430. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1431. ro [KNL] Mount root device read-only on boot
  1432. root= [KNL] Root filesystem
  1433. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1434. mount the root filesystem
  1435. rootflags= [KNL] Set root filesystem mount option string
  1436. rootfstype= [KNL] Set root filesystem type
  1437. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1438. Useful for devices that are detected asynchronously
  1439. (e.g. USB and MMC devices).
  1440. root_plug.vendor_id=
  1441. [ROOTPLUG] Override the default vendor ID
  1442. root_plug.product_id=
  1443. [ROOTPLUG] Override the default product ID
  1444. root_plug.debug=
  1445. [ROOTPLUG] Enable debugging output
  1446. rw [KNL] Mount root device read-write on boot
  1447. S [KNL] Run init in single mode
  1448. sa1100ir [NET]
  1449. See drivers/net/irda/sa1100_ir.c.
  1450. sbni= [NET] Granch SBNI12 leased line adapter
  1451. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1452. Format: <io>[,<timeout>[,<isapnp>]]
  1453. scsi_debug_*= [SCSI]
  1454. See drivers/scsi/scsi_debug.c.
  1455. scsi_default_dev_flags=
  1456. [SCSI] SCSI default device flags
  1457. Format: <integer>
  1458. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1459. Format: <vendor>:<model>:<flags>
  1460. (flags are integer value)
  1461. scsi_logging_level= [SCSI] a bit mask of logging levels
  1462. See drivers/scsi/scsi_logging.h for bits. Also
  1463. settable via sysctl at dev.scsi.logging_level
  1464. (/proc/sys/dev/scsi/logging_level).
  1465. There is also a nice 'scsi_logging_level' script in the
  1466. S390-tools package, available for download at
  1467. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1468. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1469. discovered. async scans them in kernel threads,
  1470. allowing boot to proceed. none ignores them, expecting
  1471. user space to do the scan.
  1472. selinux [SELINUX] Disable or enable SELinux at boot time.
  1473. Format: { "0" | "1" }
  1474. See security/selinux/Kconfig help text.
  1475. 0 -- disable.
  1476. 1 -- enable.
  1477. Default value is set via kernel config option.
  1478. If enabled at boot time, /selinux/disable can be used
  1479. later to disable prior to initial policy load.
  1480. selinux_compat_net =
  1481. [SELINUX] Set initial selinux_compat_net flag value.
  1482. Format: { "0" | "1" }
  1483. 0 -- use new secmark-based packet controls
  1484. 1 -- use legacy packet controls
  1485. Default value is 0 (preferred).
  1486. Value can be changed at runtime via
  1487. /selinux/compat_net.
  1488. serialnumber [BUGS=X86-32]
  1489. shapers= [NET]
  1490. Maximal number of shapers.
  1491. sim710= [SCSI,HW]
  1492. See header of drivers/scsi/sim710.c.
  1493. simeth= [IA-64]
  1494. simscsi=
  1495. slram= [HW,MTD]
  1496. slub_debug[=options[,slabs]] [MM, SLUB]
  1497. Enabling slub_debug allows one to determine the
  1498. culprit if slab objects become corrupted. Enabling
  1499. slub_debug can create guard zones around objects and
  1500. may poison objects when not in use. Also tracks the
  1501. last alloc / free. For more information see
  1502. Documentation/vm/slub.txt.
  1503. slub_max_order= [MM, SLUB]
  1504. Determines the maximum allowed order for slabs.
  1505. A high setting may cause OOMs due to memory
  1506. fragmentation. For more information see
  1507. Documentation/vm/slub.txt.
  1508. slub_min_objects= [MM, SLUB]
  1509. The minimum number of objects per slab. SLUB will
  1510. increase the slab order up to slub_max_order to
  1511. generate a sufficiently large slab able to contain
  1512. the number of objects indicated. The higher the number
  1513. of objects the smaller the overhead of tracking slabs
  1514. and the less frequently locks need to be acquired.
  1515. For more information see Documentation/vm/slub.txt.
  1516. slub_min_order= [MM, SLUB]
  1517. Determines the mininum page order for slabs. Must be
  1518. lower than slub_max_order.
  1519. For more information see Documentation/vm/slub.txt.
  1520. slub_nomerge [MM, SLUB]
  1521. Disable merging of slabs with similar size. May be
  1522. necessary if there is some reason to distinguish
  1523. allocs to different slabs. Debug options disable
  1524. merging on their own.
  1525. For more information see Documentation/vm/slub.txt.
  1526. smart2= [HW]
  1527. Format: <io1>[,<io2>[,...,<io8>]]
  1528. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1529. attempt to substitute SMP alternatives once at boot.
  1530. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1531. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1532. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1533. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1534. smsc-ircc2.ircc_irq= [HW] IRQ line
  1535. smsc-ircc2.ircc_dma= [HW] DMA channel
  1536. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1537. 0: Toshiba Satellite 1800 (GP data pin select)
  1538. 1: Fast pin select (default)
  1539. 2: ATC IRMode
  1540. snd-ad1816a= [HW,ALSA]
  1541. snd-ad1848= [HW,ALSA]
  1542. snd-ali5451= [HW,ALSA]
  1543. snd-als100= [HW,ALSA]
  1544. snd-als4000= [HW,ALSA]
  1545. snd-azt2320= [HW,ALSA]
  1546. snd-cmi8330= [HW,ALSA]
  1547. snd-cmipci= [HW,ALSA]
  1548. snd-cs4231= [HW,ALSA]
  1549. snd-cs4232= [HW,ALSA]
  1550. snd-cs4236= [HW,ALSA]
  1551. snd-cs4281= [HW,ALSA]
  1552. snd-cs46xx= [HW,ALSA]
  1553. snd-dt019x= [HW,ALSA]
  1554. snd-dummy= [HW,ALSA]
  1555. snd-emu10k1= [HW,ALSA]
  1556. snd-ens1370= [HW,ALSA]
  1557. snd-ens1371= [HW,ALSA]
  1558. snd-es968= [HW,ALSA]
  1559. snd-es1688= [HW,ALSA]
  1560. snd-es18xx= [HW,ALSA]
  1561. snd-es1938= [HW,ALSA]
  1562. snd-es1968= [HW,ALSA]
  1563. snd-fm801= [HW,ALSA]
  1564. snd-gusclassic= [HW,ALSA]
  1565. snd-gusextreme= [HW,ALSA]
  1566. snd-gusmax= [HW,ALSA]
  1567. snd-hdsp= [HW,ALSA]
  1568. snd-ice1712= [HW,ALSA]
  1569. snd-intel8x0= [HW,ALSA]
  1570. snd-interwave= [HW,ALSA]
  1571. snd-interwave-stb=
  1572. [HW,ALSA]
  1573. snd-korg1212= [HW,ALSA]
  1574. snd-maestro3= [HW,ALSA]
  1575. snd-mpu401= [HW,ALSA]
  1576. snd-mtpav= [HW,ALSA]
  1577. snd-nm256= [HW,ALSA]
  1578. snd-opl3sa2= [HW,ALSA]
  1579. snd-opti92x-ad1848=
  1580. [HW,ALSA]
  1581. snd-opti92x-cs4231=
  1582. [HW,ALSA]
  1583. snd-opti93x= [HW,ALSA]
  1584. snd-pmac= [HW,ALSA]
  1585. snd-rme32= [HW,ALSA]
  1586. snd-rme96= [HW,ALSA]
  1587. snd-rme9652= [HW,ALSA]
  1588. snd-sb8= [HW,ALSA]
  1589. snd-sb16= [HW,ALSA]
  1590. snd-sbawe= [HW,ALSA]
  1591. snd-serial= [HW,ALSA]
  1592. snd-sgalaxy= [HW,ALSA]
  1593. snd-sonicvibes= [HW,ALSA]
  1594. snd-sun-amd7930=
  1595. [HW,ALSA]
  1596. snd-sun-cs4231= [HW,ALSA]
  1597. snd-trident= [HW,ALSA]
  1598. snd-usb-audio= [HW,ALSA,USB]
  1599. snd-via82xx= [HW,ALSA]
  1600. snd-virmidi= [HW,ALSA]
  1601. snd-wavefront= [HW,ALSA]
  1602. snd-ymfpci= [HW,ALSA]
  1603. softlockup_panic=
  1604. [KNL] Should the soft-lockup detector generate panics.
  1605. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1606. See Documentation/sonypi.txt
  1607. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1608. See Documentation/specialix.txt.
  1609. spia_io_base= [HW,MTD]
  1610. spia_fio_base=
  1611. spia_pedr=
  1612. spia_peddr=
  1613. sscape= [HW,OSS]
  1614. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1615. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1616. See Documentation/scsi/st.txt.
  1617. sti= [PARISC,HW]
  1618. Format: <num>
  1619. Set the STI (builtin display/keyboard on the HP-PARISC
  1620. machines) console (graphic card) which should be used
  1621. as the initial boot-console.
  1622. See also comment in drivers/video/console/sticore.c.
  1623. sti_font= [HW]
  1624. See comment in drivers/video/console/sticore.c.
  1625. stifb= [HW]
  1626. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1627. sunrpc.pool_mode=
  1628. [NFS]
  1629. Control how the NFS server code allocates CPUs to
  1630. service thread pools. Depending on how many NICs
  1631. you have and where their interrupts are bound, this
  1632. option will affect which CPUs will do NFS serving.
  1633. Note: this parameter cannot be changed while the
  1634. NFS server is running.
  1635. auto the server chooses an appropriate mode
  1636. automatically using heuristics
  1637. global a single global pool contains all CPUs
  1638. percpu one pool for each CPU
  1639. pernode one pool for each NUMA node (equivalent
  1640. to global on non-NUMA machines)
  1641. swiotlb= [IA-64] Number of I/O TLB slabs
  1642. switches= [HW,M68k]
  1643. sym53c416= [HW,SCSI]
  1644. See header of drivers/scsi/sym53c416.c.
  1645. sysrq_always_enabled
  1646. [KNL]
  1647. Ignore sysrq setting - this boot parameter will
  1648. neutralize any effect of /proc/sys/kernel/sysrq.
  1649. Useful for debugging.
  1650. t128= [HW,SCSI]
  1651. See header of drivers/scsi/t128.c.
  1652. tdfx= [HW,DRM]
  1653. test_suspend= [SUSPEND]
  1654. Specify "mem" (for Suspend-to-RAM) or "standby" (for
  1655. standby suspend) as the system sleep state to briefly
  1656. enter during system startup. The system is woken from
  1657. this state using a wakeup-capable RTC alarm.
  1658. thash_entries= [KNL,NET]
  1659. Set number of hash buckets for TCP connection
  1660. thermal.act= [HW,ACPI]
  1661. -1: disable all active trip points in all thermal zones
  1662. <degrees C>: override all lowest active trip points
  1663. thermal.crt= [HW,ACPI]
  1664. -1: disable all critical trip points in all thermal zones
  1665. <degrees C>: lower all critical trip points
  1666. thermal.nocrt= [HW,ACPI]
  1667. Set to disable actions on ACPI thermal zone
  1668. critical and hot trip points.
  1669. thermal.off= [HW,ACPI]
  1670. 1: disable ACPI thermal control
  1671. thermal.psv= [HW,ACPI]
  1672. -1: disable all passive trip points
  1673. <degrees C>: override all passive trip points to this value
  1674. thermal.tzp= [HW,ACPI]
  1675. Specify global default ACPI thermal zone polling rate
  1676. <deci-seconds>: poll all this frequency
  1677. 0: no polling (default)
  1678. tmscsim= [HW,SCSI]
  1679. See comment before function dc390_setup() in
  1680. drivers/scsi/tmscsim.c.
  1681. tp720= [HW,PS2]
  1682. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1683. Format:
  1684. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1685. turbografx.map[2|3]= [HW,JOY]
  1686. TurboGraFX parallel port interface
  1687. Format:
  1688. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1689. See also Documentation/input/joystick-parport.txt
  1690. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1691. See header of drivers/scsi/u14-34f.c.
  1692. uart401= [HW,OSS]
  1693. Format: <io>,<irq>
  1694. uart6850= [HW,OSS]
  1695. Format: <io>,<irq>
  1696. uhci-hcd.ignore_oc=
  1697. [USB] Ignore overcurrent events (default N).
  1698. Some badly-designed motherboards generate lots of
  1699. bogus events, for ports that aren't wired to
  1700. anything. Set this parameter to avoid log spamming.
  1701. Note that genuine overcurrent events won't be
  1702. reported either.
  1703. unknown_nmi_panic
  1704. [X86-32,X86-64]
  1705. Set unknown_nmi_panic=1 early on boot.
  1706. usbcore.autosuspend=
  1707. [USB] The autosuspend time delay (in seconds) used
  1708. for newly-detected USB devices (default 2). This
  1709. is the time required before an idle device will be
  1710. autosuspended. Devices for which the delay is set
  1711. to a negative value won't be autosuspended at all.
  1712. usbhid.mousepoll=
  1713. [USBHID] The interval which mice are to be polled at.
  1714. add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
  1715. kernel's map of available physical RAM.
  1716. vdso= [X86-32,SH,x86-64]
  1717. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  1718. vdso=1: enable VDSO (default)
  1719. vdso=0: disable VDSO mapping
  1720. vdso32= [X86-32,X86-64]
  1721. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  1722. vdso32=1: enable 32-bit VDSO (default)
  1723. vdso32=0: disable 32-bit VDSO mapping
  1724. vector= [IA-64,SMP]
  1725. vector=percpu: enable percpu vector domain
  1726. video= [FB] Frame buffer configuration
  1727. See Documentation/fb/modedb.txt.
  1728. vga= [BOOT,X86-32] Select a particular video mode
  1729. See Documentation/i386/boot.txt and
  1730. Documentation/svga.txt.
  1731. Use vga=ask for menu.
  1732. This is actually a boot loader parameter; the value is
  1733. passed to the kernel using a special protocol.
  1734. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1735. size of <nn>. This can be used to increase the
  1736. minimum size (128MB on x86). It can also be used to
  1737. decrease the size and leave more room for directly
  1738. mapped kernel RAM.
  1739. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1740. Format: <command>
  1741. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1742. Format: <command>
  1743. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1744. Format: <command>
  1745. waveartist= [HW,OSS]
  1746. Format: <io>,<irq>,<dma>,<dma2>
  1747. wd33c93= [HW,SCSI]
  1748. See header of drivers/scsi/wd33c93.c.
  1749. wd7000= [HW,SCSI]
  1750. See header of drivers/scsi/wd7000.c.
  1751. wdt= [WDT] Watchdog
  1752. See Documentation/watchdog/wdt.txt.
  1753. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1754. xd_geo= See header of drivers/block/xd.c.
  1755. xirc2ps_cs= [NET,PCMCIA]
  1756. Format:
  1757. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1758. norandmaps Don't use address space randomization
  1759. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
  1760. ______________________________________________________________________
  1761. TODO:
  1762. Add documentation for ALSA options.
  1763. Add more DRM drivers.