kernel-parameters.txt 80 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. IMA Integrity measurement architecture is enabled.
  40. IOSCHED More than one I/O scheduler is enabled.
  41. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  42. ISAPNP ISA PnP code is enabled.
  43. ISDN Appropriate ISDN support is enabled.
  44. JOY Appropriate joystick support is enabled.
  45. LIBATA Libata driver is enabled
  46. LP Printer support is enabled.
  47. LOOP Loopback device support is enabled.
  48. M68k M68k architecture is enabled.
  49. These options have more detailed description inside of
  50. Documentation/m68k/kernel-options.txt.
  51. MCA MCA bus support is enabled.
  52. MDA MDA console support is enabled.
  53. MOUSE Appropriate mouse support is enabled.
  54. MSI Message Signaled Interrupts (PCI).
  55. MTD MTD (Memory Technology Device) support is enabled.
  56. NET Appropriate network support is enabled.
  57. NUMA NUMA support is enabled.
  58. GENERIC_TIME The generic timeofday code is enabled.
  59. NFS Appropriate NFS support is enabled.
  60. OSS OSS sound support is enabled.
  61. PV_OPS A paravirtualized kernel is enabled.
  62. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  63. PARISC The PA-RISC architecture is enabled.
  64. PCI PCI bus support is enabled.
  65. PCIE PCI Express support is enabled.
  66. PCMCIA The PCMCIA subsystem is enabled.
  67. PNP Plug & Play support is enabled.
  68. PPC PowerPC architecture is enabled.
  69. PPT Parallel port support is enabled.
  70. PS2 Appropriate PS/2 support is enabled.
  71. RAM RAM disk support is enabled.
  72. ROOTPLUG The example Root Plug LSM is enabled.
  73. S390 S390 architecture is enabled.
  74. SCSI Appropriate SCSI support is enabled.
  75. A lot of drivers has their options described inside of
  76. Documentation/scsi/.
  77. SECURITY Different security models are enabled.
  78. SELINUX SELinux support is enabled.
  79. SERIAL Serial support is enabled.
  80. SH SuperH architecture is enabled.
  81. SMP The kernel is an SMP kernel.
  82. SPARC Sparc architecture is enabled.
  83. SWSUSP Software suspend (hibernation) is enabled.
  84. SUSPEND System suspend states are enabled.
  85. FTRACE Function tracing enabled.
  86. TS Appropriate touchscreen support is enabled.
  87. UMS USB Mass Storage support is enabled.
  88. USB USB support is enabled.
  89. USBHID USB Human Interface Device support is enabled.
  90. V4L Video For Linux support is enabled.
  91. VGA The VGA console has been enabled.
  92. VT Virtual terminal support is enabled.
  93. WDT Watchdog support is enabled.
  94. XT IBM PC/XT MFM hard disk support is enabled.
  95. X86-32 X86-32, aka i386 architecture is enabled.
  96. X86-64 X86-64 architecture is enabled.
  97. More X86-64 boot options can be found in
  98. Documentation/x86/x86_64/boot-options.txt .
  99. X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
  100. In addition, the following text indicates that the option:
  101. BUGS= Relates to possible processor bugs on the said processor.
  102. KNL Is a kernel start-up parameter.
  103. BOOT Is a boot loader parameter.
  104. Parameters denoted with BOOT are actually interpreted by the boot
  105. loader, and have no meaning to the kernel directly.
  106. Do not modify the syntax of boot loader parameters without extreme
  107. need or coordination with <Documentation/x86/boot.txt>.
  108. There are also arch-specific kernel-parameters not documented here.
  109. See for example <Documentation/x86/x86_64/boot-options.txt>.
  110. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  111. a trailing = on the name of any parameter states that that parameter will
  112. be entered as an environment variable, whereas its absence indicates that
  113. it will appear as a kernel argument readable via /proc/cmdline by programs
  114. running once the system is up.
  115. The number of kernel parameters is not limited, but the length of the
  116. complete command line (parameters including spaces etc.) is limited to
  117. a fixed number of characters. This limit depends on the architecture
  118. and is between 256 and 4096 characters. It is defined in the file
  119. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  120. acpi= [HW,ACPI,X86-64,i386]
  121. Advanced Configuration and Power Interface
  122. Format: { force | off | ht | strict | noirq | rsdt }
  123. force -- enable ACPI if default was off
  124. off -- disable ACPI if default was on
  125. noirq -- do not use ACPI for IRQ routing
  126. ht -- run only enough ACPI to enable Hyper Threading
  127. strict -- Be less tolerant of platforms that are not
  128. strictly ACPI specification compliant.
  129. rsdt -- prefer RSDT over (default) XSDT
  130. See also Documentation/power/pm.txt, pci=noacpi
  131. acpi_apic_instance= [ACPI, IOAPIC]
  132. Format: <int>
  133. 2: use 2nd APIC table, if available
  134. 1,0: use 1st APIC table
  135. default: 0
  136. acpi_sleep= [HW,ACPI] Sleep options
  137. Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
  138. old_ordering, s4_nonvs }
  139. See Documentation/power/video.txt for information on
  140. s3_bios and s3_mode.
  141. s3_beep is for debugging; it makes the PC's speaker beep
  142. as soon as the kernel's real-mode entry point is called.
  143. s4_nohwsig prevents ACPI hardware signature from being
  144. used during resume from hibernation.
  145. old_ordering causes the ACPI 1.0 ordering of the _PTS
  146. control method, with respect to putting devices into
  147. low power states, to be enforced (the ACPI 2.0 ordering
  148. of _PTS is used by default).
  149. s4_nonvs prevents the kernel from saving/restoring the
  150. ACPI NVS memory during hibernation.
  151. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  152. Format: { level | edge | high | low }
  153. acpi_irq_balance [HW,ACPI]
  154. ACPI will balance active IRQs
  155. default in APIC mode
  156. acpi_irq_nobalance [HW,ACPI]
  157. ACPI will not move active IRQs (default)
  158. default in PIC mode
  159. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  160. use by PCI
  161. Format: <irq>,<irq>...
  162. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  163. Format: <irq>,<irq>...
  164. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  165. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  166. Format: To spoof as Windows 98: ="Microsoft Windows"
  167. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  168. acpi_osi="string1" # add string1 -- only one string
  169. acpi_osi="!string2" # remove built-in string2
  170. acpi_osi= # disable all strings
  171. acpi_serialize [HW,ACPI] force serialization of AML methods
  172. acpi_skip_timer_override [HW,ACPI]
  173. Recognize and ignore IRQ0/pin2 Interrupt Override.
  174. For broken nForce2 BIOS resulting in XT-PIC timer.
  175. acpi_use_timer_override [HW,ACPI]
  176. Use timer override. For some broken Nvidia NF5 boards
  177. that require a timer override, but don't have
  178. HPET
  179. acpi_backlight= [HW,ACPI]
  180. acpi_backlight=vendor
  181. acpi_backlight=video
  182. If set to vendor, prefer vendor specific driver
  183. (e.g. thinkpad_acpi, sony_acpi, etc.) instead
  184. of the ACPI video.ko driver.
  185. acpi_display_output= [HW,ACPI]
  186. acpi_display_output=vendor
  187. acpi_display_output=video
  188. See above.
  189. acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
  190. acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
  191. Format: <int>
  192. CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
  193. debug output. Bits in debug_layer correspond to a
  194. _COMPONENT in an ACPI source file, e.g.,
  195. #define _COMPONENT ACPI_PCI_COMPONENT
  196. Bits in debug_level correspond to a level in
  197. ACPI_DEBUG_PRINT statements, e.g.,
  198. ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
  199. The debug_level mask defaults to "info". See
  200. Documentation/acpi/debug.txt for more information about
  201. debug layers and levels.
  202. Enable processor driver info messages:
  203. acpi.debug_layer=0x20000000
  204. Enable PCI/PCI interrupt routing info messages:
  205. acpi.debug_layer=0x400000
  206. Enable AML "Debug" output, i.e., stores to the Debug
  207. object while interpreting AML:
  208. acpi.debug_layer=0xffffffff acpi.debug_level=0x2
  209. Enable all messages related to ACPI hardware:
  210. acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
  211. Some values produce so much output that the system is
  212. unusable. The "log_buf_len" parameter may be useful
  213. if you need to capture more output.
  214. acpi.power_nocheck= [HW,ACPI]
  215. Format: 1/0 enable/disable the check of power state.
  216. On some bogus BIOS the _PSC object/_STA object of
  217. power resource can't return the correct device power
  218. state. In such case it is unneccessary to check its
  219. power state again in power transition.
  220. 1 : disable the power state check
  221. acpi_pm_good [X86-32,X86-64]
  222. Override the pmtimer bug detection: force the kernel
  223. to assume that this machine's pmtimer latches its value
  224. and always returns good values.
  225. agp= [AGP]
  226. { off | try_unsupported }
  227. off: disable AGP support
  228. try_unsupported: try to drive unsupported chipsets
  229. (may crash computer or cause data corruption)
  230. enable_timer_pin_1 [i386,x86-64]
  231. Enable PIN 1 of APIC timer
  232. Can be useful to work around chipset bugs
  233. (in particular on some ATI chipsets).
  234. The kernel tries to set a reasonable default.
  235. disable_timer_pin_1 [i386,x86-64]
  236. Disable PIN 1 of APIC timer
  237. Can be useful to work around chipset bugs.
  238. ad1848= [HW,OSS]
  239. Format: <io>,<irq>,<dma>,<dma2>,<type>
  240. advansys= [HW,SCSI]
  241. See header of drivers/scsi/advansys.c.
  242. advwdt= [HW,WDT] Advantech WDT
  243. Format: <iostart>,<iostop>
  244. aedsp16= [HW,OSS] Audio Excel DSP 16
  245. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  246. See also header of sound/oss/aedsp16.c.
  247. aha152x= [HW,SCSI]
  248. See Documentation/scsi/aha152x.txt.
  249. aha1542= [HW,SCSI]
  250. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  251. aic7xxx= [HW,SCSI]
  252. See Documentation/scsi/aic7xxx.txt.
  253. aic79xx= [HW,SCSI]
  254. See Documentation/scsi/aic79xx.txt.
  255. amd_iommu= [HW,X86-84]
  256. Pass parameters to the AMD IOMMU driver in the system.
  257. Possible values are:
  258. isolate - enable device isolation (each device, as far
  259. as possible, will get its own protection
  260. domain) [default]
  261. share - put every device behind one IOMMU into the
  262. same protection domain
  263. fullflush - enable flushing of IO/TLB entries when
  264. they are unmapped. Otherwise they are
  265. flushed before they will be reused, which
  266. is a lot of faster
  267. amd_iommu_size= [HW,X86-64]
  268. Define the size of the aperture for the AMD IOMMU
  269. driver. Possible values are:
  270. '32M', '64M' (default), '128M', '256M', '512M', '1G'
  271. amijoy.map= [HW,JOY] Amiga joystick support
  272. Map of devices attached to JOY0DAT and JOY1DAT
  273. Format: <a>,<b>
  274. See also Documentation/kernel/input/joystick.txt
  275. analog.map= [HW,JOY] Analog joystick and gamepad support
  276. Specifies type or capabilities of an analog joystick
  277. connected to one of 16 gameports
  278. Format: <type1>,<type2>,..<type16>
  279. apc= [HW,SPARC]
  280. Power management functions (SPARCstation-4/5 + deriv.)
  281. Format: noidle
  282. Disable APC CPU standby support. SPARCstation-Fox does
  283. not play well with APC CPU idle - disable it if you have
  284. APC and your system crashes randomly.
  285. apic= [APIC,i386] Advanced Programmable Interrupt Controller
  286. Change the output verbosity whilst booting
  287. Format: { quiet (default) | verbose | debug }
  288. Change the amount of debugging information output
  289. when initialising the APIC and IO-APIC components.
  290. apm= [APM] Advanced Power Management
  291. See header of arch/x86/kernel/apm_32.c.
  292. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  293. Format: <io>,<irq>,<nodeID>
  294. ataflop= [HW,M68k]
  295. atarimouse= [HW,MOUSE] Atari Mouse
  296. atascsi= [HW,SCSI] Atari SCSI
  297. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  298. EzKey and similar keyboards
  299. atkbd.reset= [HW] Reset keyboard during initialization
  300. atkbd.set= [HW] Select keyboard code set
  301. Format: <int> (2 = AT (default), 3 = PS/2)
  302. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  303. keyboards
  304. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  305. Format: <bool> (0 = real, 1 = synthetic (default))
  306. atkbd.softrepeat= [HW]
  307. Use software keyboard repeat
  308. autotest [IA64]
  309. baycom_epp= [HW,AX25]
  310. Format: <io>,<mode>
  311. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  312. Format: <io>,<mode>
  313. See header of drivers/net/hamradio/baycom_par.c.
  314. baycom_ser_fdx= [HW,AX25]
  315. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  316. Format: <io>,<irq>,<mode>[,<baud>]
  317. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  318. baycom_ser_hdx= [HW,AX25]
  319. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  320. Format: <io>,<irq>,<mode>
  321. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  322. boot_delay= Milliseconds to delay each printk during boot.
  323. Values larger than 10 seconds (10000) are changed to
  324. no delay (0).
  325. Format: integer
  326. bootmem_debug [KNL] Enable bootmem allocator debug messages.
  327. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  328. bttv.radio= Most important insmod options are available as
  329. kernel args too.
  330. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  331. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  332. BusLogic= [HW,SCSI]
  333. See drivers/scsi/BusLogic.c, comment before function
  334. BusLogic_ParseDriverOptions().
  335. c101= [NET] Moxa C101 synchronous serial card
  336. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  337. Sometimes CPU hardware bugs make them report the cache
  338. size incorrectly. The kernel will attempt work arounds
  339. to fix known problems, but for some CPUs it is not
  340. possible to determine what the correct size should be.
  341. This option provides an override for these situations.
  342. security= [SECURITY] Choose a security module to enable at boot.
  343. If this boot parameter is not specified, only the first
  344. security module asking for security registration will be
  345. loaded. An invalid security module name will be treated
  346. as if no module has been chosen.
  347. capability.disable=
  348. [SECURITY] Disable capabilities. This would normally
  349. be used only if an alternative security model is to be
  350. configured. Potentially dangerous and should only be
  351. used if you are entirely sure of the consequences.
  352. ccw_timeout_log [S390]
  353. See Documentation/s390/CommonIO for details.
  354. cgroup_disable= [KNL] Disable a particular controller
  355. Format: {name of the controller(s) to disable}
  356. {Currently supported controllers - "memory"}
  357. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  358. Format: { "0" | "1" }
  359. See security/selinux/Kconfig help text.
  360. 0 -- check protection applied by kernel (includes
  361. any implied execute protection).
  362. 1 -- check protection requested by application.
  363. Default value is set via a kernel config option.
  364. Value can be changed at runtime via
  365. /selinux/checkreqprot.
  366. cio_ignore= [S390]
  367. See Documentation/s390/CommonIO for details.
  368. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  369. [Deprecated]
  370. Forces specified clocksource (if available) to be used
  371. when calculating gettimeofday(). If specified
  372. clocksource is not available, it defaults to PIT.
  373. Format: { pit | tsc | cyclone | pmtmr }
  374. clocksource= [GENERIC_TIME] Override the default clocksource
  375. Format: <string>
  376. Override the default clocksource and use the clocksource
  377. with the name specified.
  378. Some clocksource names to choose from, depending on
  379. the platform:
  380. [all] jiffies (this is the base, fallback clocksource)
  381. [ACPI] acpi_pm
  382. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  383. pxa_timer,timer3,32k_counter,timer0_1
  384. [AVR32] avr32
  385. [X86-32] pit,hpet,tsc,vmi-timer;
  386. scx200_hrt on Geode; cyclone on IBM x440
  387. [MIPS] MIPS
  388. [PARISC] cr16
  389. [S390] tod
  390. [SH] SuperH
  391. [SPARC64] tick
  392. [X86-64] hpet,tsc
  393. clearcpuid=BITNUM [X86]
  394. Disable CPUID feature X for the kernel. See
  395. arch/x86/include/asm/cpufeature.h for the valid bit
  396. numbers. Note the Linux specific bits are not necessarily
  397. stable over kernel options, but the vendor specific
  398. ones should be.
  399. Also note that user programs calling CPUID directly
  400. or using the feature without checking anything
  401. will still see it. This just prevents it from
  402. being used by the kernel or shown in /proc/cpuinfo.
  403. Also note the kernel might malfunction if you disable
  404. some critical bits.
  405. code_bytes [IA32/X86_64] How many bytes of object code to print
  406. in an oops report.
  407. Range: 0 - 8192
  408. Default: 64
  409. dma_debug=off If the kernel is compiled with DMA_API_DEBUG support
  410. this option disables the debugging code at boot.
  411. dma_debug_entries=<number>
  412. This option allows to tune the number of preallocated
  413. entries for DMA-API debugging code. One entry is
  414. required per DMA-API allocation. Use this if the
  415. DMA-API debugging code disables itself because the
  416. architectural default is too low.
  417. hpet= [X86-32,HPET] option to control HPET usage
  418. Format: { enable (default) | disable | force |
  419. verbose }
  420. disable: disable HPET and use PIT instead
  421. force: allow force enabled of undocumented chips (ICH4,
  422. VIA, nVidia)
  423. verbose: show contents of HPET registers during setup
  424. com20020= [HW,NET] ARCnet - COM20020 chipset
  425. Format:
  426. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  427. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  428. Format: <io>[,<irq>]
  429. com90xx= [HW,NET]
  430. ARCnet - COM90xx chipset (memory-mapped buffers)
  431. Format: <io>[,<irq>[,<memstart>]]
  432. condev= [HW,S390] console device
  433. conmode=
  434. console= [KNL] Output console device and options.
  435. tty<n> Use the virtual console device <n>.
  436. ttyS<n>[,options]
  437. ttyUSB0[,options]
  438. Use the specified serial port. The options are of
  439. the form "bbbbpnf", where "bbbb" is the baud rate,
  440. "p" is parity ("n", "o", or "e"), "n" is number of
  441. bits, and "f" is flow control ("r" for RTS or
  442. omit it). Default is "9600n8".
  443. See Documentation/serial-console.txt for more
  444. information. See
  445. Documentation/networking/netconsole.txt for an
  446. alternative.
  447. uart[8250],io,<addr>[,options]
  448. uart[8250],mmio,<addr>[,options]
  449. Start an early, polled-mode console on the 8250/16550
  450. UART at the specified I/O port or MMIO address,
  451. switching to the matching ttyS device later. The
  452. options are the same as for ttyS, above.
  453. If the device connected to the port is not a TTY but a braille
  454. device, prepend "brl," before the device type, for instance
  455. console=brl,ttyS0
  456. For now, only VisioBraille is supported.
  457. earlycon= [KNL] Output early console device and options.
  458. uart[8250],io,<addr>[,options]
  459. uart[8250],mmio,<addr>[,options]
  460. Start an early, polled-mode console on the 8250/16550
  461. UART at the specified I/O port or MMIO address.
  462. The options are the same as for ttyS, above.
  463. no_console_suspend
  464. [HW] Never suspend the console
  465. Disable suspending of consoles during suspend and
  466. hibernate operations. Once disabled, debugging
  467. messages can reach various consoles while the rest
  468. of the system is being put to sleep (ie, while
  469. debugging driver suspend/resume hooks). This may
  470. not work reliably with all consoles, but is known
  471. to work with serial and VGA consoles.
  472. coredump_filter=
  473. [KNL] Change the default value for
  474. /proc/<pid>/coredump_filter.
  475. See also Documentation/filesystems/proc.txt.
  476. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  477. Format:
  478. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  479. crashkernel=nn[KMG]@ss[KMG]
  480. [KNL] Reserve a chunk of physical memory to
  481. hold a kernel to switch to with kexec on panic.
  482. crashkernel=range1:size1[,range2:size2,...][@offset]
  483. [KNL] Same as above, but depends on the memory
  484. in the running system. The syntax of range is
  485. start-[end] where start and end are both
  486. a memory unit (amount[KMG]). See also
  487. Documentation/kdump/kdump.txt for a example.
  488. cs89x0_dma= [HW,NET]
  489. Format: <dma>
  490. cs89x0_media= [HW,NET]
  491. Format: { rj45 | aui | bnc }
  492. dasd= [HW,NET]
  493. See header of drivers/s390/block/dasd_devmap.c.
  494. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  495. (one device per port)
  496. Format: <port#>,<type>
  497. See also Documentation/input/joystick-parport.txt
  498. debug [KNL] Enable kernel debugging (events log level).
  499. debug_locks_verbose=
  500. [KNL] verbose self-tests
  501. Format=<0|1>
  502. Print debugging info while doing the locking API
  503. self-tests.
  504. We default to 0 (no extra messages), setting it to
  505. 1 will print _a lot_ more information - normally
  506. only useful to kernel developers.
  507. debug_objects [KNL] Enable object debugging
  508. debugpat [X86] Enable PAT debugging
  509. decnet.addr= [HW,NET]
  510. Format: <area>[,<node>]
  511. See also Documentation/networking/decnet.txt.
  512. vt.default_blu= [VT]
  513. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  514. Change the default blue palette of the console.
  515. This is a 16-member array composed of values
  516. ranging from 0-255.
  517. vt.default_grn= [VT]
  518. Format: <green0>,<green1>,<green2>,...,<green15>
  519. Change the default green palette of the console.
  520. This is a 16-member array composed of values
  521. ranging from 0-255.
  522. vt.default_red= [VT]
  523. Format: <red0>,<red1>,<red2>,...,<red15>
  524. Change the default red palette of the console.
  525. This is a 16-member array composed of values
  526. ranging from 0-255.
  527. vt.default_utf8=
  528. [VT]
  529. Format=<0|1>
  530. Set system-wide default UTF-8 mode for all tty's.
  531. Default is 1, i.e. UTF-8 mode is enabled for all
  532. newly opened terminals.
  533. dhash_entries= [KNL]
  534. Set number of hash buckets for dentry cache.
  535. digi= [HW,SERIAL]
  536. IO parameters + enable/disable command.
  537. digiepca= [HW,SERIAL]
  538. See drivers/char/README.epca and
  539. Documentation/serial/digiepca.txt.
  540. disable_mtrr_cleanup [X86]
  541. enable_mtrr_cleanup [X86]
  542. The kernel tries to adjust MTRR layout from continuous
  543. to discrete, to make X server driver able to add WB
  544. entry later. This parameter enables/disables that.
  545. mtrr_chunk_size=nn[KMG] [X86]
  546. used for mtrr cleanup. It is largest continous chunk
  547. that could hold holes aka. UC entries.
  548. mtrr_gran_size=nn[KMG] [X86]
  549. Used for mtrr cleanup. It is granularity of mtrr block.
  550. Default is 1.
  551. Large value could prevent small alignment from
  552. using up MTRRs.
  553. mtrr_spare_reg_nr=n [X86]
  554. Format: <integer>
  555. Range: 0,7 : spare reg number
  556. Default : 1
  557. Used for mtrr cleanup. It is spare mtrr entries number.
  558. Set to 2 or more if your graphical card needs more.
  559. disable_mtrr_trim [X86, Intel and AMD only]
  560. By default the kernel will trim any uncacheable
  561. memory out of your available memory pool based on
  562. MTRR settings. This parameter disables that behavior,
  563. possibly causing your machine to run very slowly.
  564. dmasound= [HW,OSS] Sound subsystem buffers
  565. dscc4.setup= [NET]
  566. dtc3181e= [HW,SCSI]
  567. earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
  568. earlyprintk=vga
  569. earlyprintk=serial[,ttySn[,baudrate]]
  570. earlyprintk=dbgp
  571. Append ",keep" to not disable it when the real console
  572. takes over.
  573. Only vga or serial or usb debug port at a time.
  574. Currently only ttyS0 and ttyS1 are supported.
  575. Interaction with the standard serial driver is not
  576. very good.
  577. The VGA output is eventually overwritten by the real
  578. console.
  579. eata= [HW,SCSI]
  580. edd= [EDD]
  581. Format: {"off" | "on" | "skip[mbr]"}
  582. eisa_irq_edge= [PARISC,HW]
  583. See header of drivers/parisc/eisa.c.
  584. elanfreq= [X86-32]
  585. See comment before function elanfreq_setup() in
  586. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
  587. elevator= [IOSCHED]
  588. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  589. See Documentation/block/as-iosched.txt and
  590. Documentation/block/deadline-iosched.txt for details.
  591. elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
  592. Specifies physical address of start of kernel core
  593. image elf header. Generally kexec loader will
  594. pass this option to capture kernel.
  595. See Documentation/kdump/kdump.txt for details.
  596. enforcing [SELINUX] Set initial enforcing status.
  597. Format: {"0" | "1"}
  598. See security/selinux/Kconfig help text.
  599. 0 -- permissive (log only, no denials).
  600. 1 -- enforcing (deny and log).
  601. Default value is 0.
  602. Value can be changed at runtime via /selinux/enforce.
  603. ether= [HW,NET] Ethernet cards parameters
  604. This option is obsoleted by the "netdev=" option, which
  605. has equivalent usage. See its documentation for details.
  606. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  607. Format: <io>[,<irq>]
  608. failslab=
  609. fail_page_alloc=
  610. fail_make_request=[KNL]
  611. General fault injection mechanism.
  612. Format: <interval>,<probability>,<space>,<times>
  613. See also /Documentation/fault-injection/.
  614. fd_mcs= [HW,SCSI]
  615. See header of drivers/scsi/fd_mcs.c.
  616. fdomain= [HW,SCSI]
  617. See header of drivers/scsi/fdomain.c.
  618. floppy= [HW]
  619. See Documentation/blockdev/floppy.txt.
  620. force_pal_cache_flush
  621. [IA-64] Avoid check_sal_cache_flush which may hang on
  622. buggy SAL_CACHE_FLUSH implementations. Using this
  623. parameter will force ia64_sal_cache_flush to call
  624. ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
  625. ftrace=[tracer]
  626. [ftrace] will set and start the specified tracer
  627. as early as possible in order to facilitate early
  628. boot debugging.
  629. ftrace_dump_on_oops
  630. [ftrace] will dump the trace buffers on oops.
  631. gamecon.map[2|3]=
  632. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  633. support via parallel port (up to 5 devices per port)
  634. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  635. See also Documentation/input/joystick-parport.txt
  636. gamma= [HW,DRM]
  637. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  638. Format: off | on
  639. default: on
  640. gdth= [HW,SCSI]
  641. See header of drivers/scsi/gdth.c.
  642. gpt [EFI] Forces disk with valid GPT signature but
  643. invalid Protective MBR to be treated as GPT.
  644. gvp11= [HW,SCSI]
  645. hashdist= [KNL,NUMA] Large hashes allocated during boot
  646. are distributed across NUMA nodes. Defaults on
  647. for IA-64, off otherwise.
  648. Format: 0 | 1 (for off | on)
  649. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  650. hd= [EIDE] (E)IDE hard drive subsystem geometry
  651. Format: <cyl>,<head>,<sect>
  652. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  653. size of <nn>. This works even on boxes that have no
  654. highmem otherwise. This also works to reduce highmem
  655. size on bigger boxes.
  656. highres= [KNL] Enable/disable high resolution timer mode.
  657. Valid parameters: "on", "off"
  658. Default: "on"
  659. hisax= [HW,ISDN]
  660. See Documentation/isdn/README.HiSax.
  661. hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
  662. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
  663. On x86-64 and powerpc, this option can be specified
  664. multiple times interleaved with hugepages= to reserve
  665. huge pages of different sizes. Valid pages sizes on
  666. x86-64 are 2M (when the CPU supports "pse") and 1G
  667. (when the CPU supports the "pdpe1gb" cpuinfo flag)
  668. Note that 1GB pages can only be allocated at boot time
  669. using hugepages= and not freed afterwards.
  670. default_hugepagesz=
  671. [same as hugepagesz=] The size of the default
  672. HugeTLB page size. This is the size represented by
  673. the legacy /proc/ hugepages APIs, used for SHM, and
  674. default size when mounting hugetlbfs filesystems.
  675. Defaults to the default architecture's huge page size
  676. if not specified.
  677. hlt [BUGS=ARM,SH]
  678. hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
  679. terminal devices. Valid values: 0..8
  680. hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
  681. If specified, z/VM IUCV HVC accepts connections
  682. from listed z/VM user IDs only.
  683. i2c_bus= [HW] Override the default board specific I2C bus speed
  684. or register an additional I2C bus that is not
  685. registered from board initialization code.
  686. Format:
  687. <bus_id>,<clkrate>
  688. i8042.debug [HW] Toggle i8042 debug mode
  689. i8042.direct [HW] Put keyboard port into non-translated mode
  690. i8042.dumbkbd [HW] Pretend that controller can only read data from
  691. keyboard and cannot control its state
  692. (Don't attempt to blink the leds)
  693. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  694. i8042.nokbd [HW] Don't check/create keyboard port
  695. i8042.noloop [HW] Disable the AUX Loopback command while probing
  696. for the AUX port
  697. i8042.nomux [HW] Don't check presence of an active multiplexing
  698. controller
  699. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  700. controllers
  701. i8042.panicblink=
  702. [HW] Frequency with which keyboard LEDs should blink
  703. when kernel panics (default is 0.5 sec)
  704. i8042.reset [HW] Reset the controller during init and cleanup
  705. i8042.unlock [HW] Unlock (ignore) the keylock
  706. i810= [HW,DRM]
  707. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  708. indicates that the driver is running on unsupported
  709. hardware.
  710. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  711. does not match list of supported models.
  712. i8k.power_status
  713. [HW] Report power status in /proc/i8k
  714. (disabled by default)
  715. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  716. capability is set.
  717. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  718. See Documentation/mca.txt.
  719. icn= [HW,ISDN]
  720. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  721. ide-core.nodma= [HW] (E)IDE subsystem
  722. Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
  723. .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
  724. .chs .ignore_cable are additional options
  725. See Documentation/ide/ide.txt.
  726. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  727. See Documentation/ide/ide.txt.
  728. idle= [X86]
  729. Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
  730. Poll forces a polling idle loop that can slightly
  731. improve the performance of waking up a idle CPU, but
  732. will use a lot of power and make the system run hot.
  733. Not recommended.
  734. idle=mwait: On systems which support MONITOR/MWAIT but
  735. the kernel chose to not use it because it doesn't save
  736. as much power as a normal idle loop, use the
  737. MONITOR/MWAIT idle loop anyways. Performance should be
  738. the same as idle=poll.
  739. idle=halt: Halt is forced to be used for CPU idle.
  740. In such case C2/C3 won't be used again.
  741. idle=nomwait: Disable mwait for CPU C-states
  742. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  743. Claim all unknown PCI IDE storage controllers.
  744. ignore_loglevel [KNL]
  745. Ignore loglevel setting - this will print /all/
  746. kernel messages to the console. Useful for debugging.
  747. ihash_entries= [KNL]
  748. Set number of hash buckets for inode cache.
  749. ima_audit= [IMA]
  750. Format: { "0" | "1" }
  751. 0 -- integrity auditing messages. (Default)
  752. 1 -- enable informational integrity auditing messages.
  753. ima_hash= [IMA]
  754. Formt: { "sha1" | "md5" }
  755. default: "sha1"
  756. in2000= [HW,SCSI]
  757. See header of drivers/scsi/in2000.c.
  758. init= [KNL]
  759. Format: <full_path>
  760. Run specified binary instead of /sbin/init as init
  761. process.
  762. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  763. for working out where the kernel is dying during
  764. startup.
  765. initrd= [BOOT] Specify the location of the initial ramdisk
  766. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  767. Format: <irq>
  768. inttest= [IA64]
  769. iomem= Disable strict checking of access to MMIO memory
  770. strict regions from userspace.
  771. relaxed
  772. iommu= [x86]
  773. off
  774. force
  775. noforce
  776. biomerge
  777. panic
  778. nopanic
  779. merge
  780. nomerge
  781. forcesac
  782. soft
  783. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  784. on
  785. Enable intel iommu driver.
  786. off
  787. Disable intel iommu driver.
  788. igfx_off [Default Off]
  789. By default, gfx is mapped as normal device. If a gfx
  790. device has a dedicated DMAR unit, the DMAR unit is
  791. bypassed by not enabling DMAR with this option. In
  792. this case, gfx device will use physical address for
  793. DMA.
  794. forcedac [x86_64]
  795. With this option iommu will not optimize to look
  796. for io virtual address below 32 bit forcing dual
  797. address cycle on pci bus for cards supporting greater
  798. than 32 bit addressing. The default is to look
  799. for translation below 32 bit and if not available
  800. then look in the higher range.
  801. strict [Default Off]
  802. With this option on every unmap_single operation will
  803. result in a hardware IOTLB flush operation as opposed
  804. to batching them for performance.
  805. io_delay= [X86-32,X86-64] I/O delay method
  806. 0x80
  807. Standard port 0x80 based delay
  808. 0xed
  809. Alternate port 0xed based delay (needed on some systems)
  810. udelay
  811. Simple two microseconds delay
  812. none
  813. No delay
  814. io7= [HW] IO7 for Marvel based alpha systems
  815. See comment before marvel_specify_io7 in
  816. arch/alpha/kernel/core_marvel.c.
  817. ip= [IP_PNP]
  818. See Documentation/filesystems/nfsroot.txt.
  819. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  820. See comment before ip2_setup() in
  821. drivers/char/ip2/ip2base.c.
  822. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  823. See header of drivers/scsi/ips.c.
  824. ports= [IP_VS_FTP] IPVS ftp helper module
  825. Default is 21.
  826. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  827. may be specified.
  828. Format: <port>,<port>....
  829. irqfixup [HW]
  830. When an interrupt is not handled search all handlers
  831. for it. Intended to get systems with badly broken
  832. firmware running.
  833. irqpoll [HW]
  834. When an interrupt is not handled search all handlers
  835. for it. Also check all handlers each timer
  836. interrupt. Intended to get systems with badly broken
  837. firmware running.
  838. isapnp= [ISAPNP]
  839. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  840. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  841. Format:
  842. <cpu number>,...,<cpu number>
  843. or
  844. <cpu number>-<cpu number>
  845. (must be a positive range in ascending order)
  846. or a mixture
  847. <cpu number>,...,<cpu number>-<cpu number>
  848. This option can be used to specify one or more CPUs
  849. to isolate from the general SMP balancing and scheduling
  850. algorithms. You can move a process onto or off an
  851. "isolated" CPU via the CPU affinity syscalls or cpuset.
  852. <cpu number> begins at 0 and the maximum value is
  853. "number of CPUs in system - 1".
  854. This option is the preferred way to isolate CPUs. The
  855. alternative -- manually setting the CPU mask of all
  856. tasks in the system -- can cause problems and
  857. suboptimal load balancer performance.
  858. iucv= [HW,NET]
  859. js= [HW,JOY] Analog joystick
  860. See Documentation/input/joystick.txt.
  861. kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  862. specifies the amount of memory usable by the kernel
  863. for non-movable allocations. The requested amount is
  864. spread evenly throughout all nodes in the system. The
  865. remaining memory in each node is used for Movable
  866. pages. In the event, a node is too small to have both
  867. kernelcore and Movable pages, kernelcore pages will
  868. take priority and other nodes will have a larger number
  869. of kernelcore pages. The Movable zone is used for the
  870. allocation of pages that may be reclaimed or moved
  871. by the page migration subsystem. This means that
  872. HugeTLB pages may not be allocated from this zone.
  873. Note that allocations like PTEs-from-HighMem still
  874. use the HighMem zone if it exists, and the Normal
  875. zone if it does not.
  876. movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
  877. is similar to kernelcore except it specifies the
  878. amount of memory used for migratable allocations.
  879. If both kernelcore and movablecore is specified,
  880. then kernelcore will be at *least* the specified
  881. value but may be more. If movablecore on its own
  882. is specified, the administrator must be careful
  883. that the amount of memory usable for all allocations
  884. is not too small.
  885. keepinitrd [HW,ARM]
  886. kstack=N [X86-32,X86-64] Print N words from the kernel stack
  887. in oops dumps.
  888. kgdboc= [HW] kgdb over consoles.
  889. Requires a tty driver that supports console polling.
  890. (only serial suported for now)
  891. Format: <serial_device>[,baud]
  892. kmac= [MIPS] korina ethernet MAC address.
  893. Configure the RouterBoard 532 series on-chip
  894. Ethernet adapter MAC address.
  895. l2cr= [PPC]
  896. l3cr= [PPC]
  897. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  898. disabled it.
  899. lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
  900. in C2 power state.
  901. libata.dma= [LIBATA] DMA control
  902. libata.dma=0 Disable all PATA and SATA DMA
  903. libata.dma=1 PATA and SATA Disk DMA only
  904. libata.dma=2 ATAPI (CDROM) DMA only
  905. libata.dma=4 Compact Flash DMA only
  906. Combinations also work, so libata.dma=3 enables DMA
  907. for disks and CDROMs, but not CFs.
  908. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  909. when set.
  910. Format: <int>
  911. libata.force= [LIBATA] Force configurations. The format is comma
  912. separated list of "[ID:]VAL" where ID is
  913. PORT[:DEVICE]. PORT and DEVICE are decimal numbers
  914. matching port, link or device. Basically, it matches
  915. the ATA ID string printed on console by libata. If
  916. the whole ID part is omitted, the last PORT and DEVICE
  917. values are used. If ID hasn't been specified yet, the
  918. configuration applies to all ports, links and devices.
  919. If only DEVICE is omitted, the parameter applies to
  920. the port and all links and devices behind it. DEVICE
  921. number of 0 either selects the first device or the
  922. first fan-out link behind PMP device. It does not
  923. select the host link. DEVICE number of 15 selects the
  924. host link and device attached to it.
  925. The VAL specifies the configuration to force. As long
  926. as there's no ambiguity shortcut notation is allowed.
  927. For example, both 1.5 and 1.5G would work for 1.5Gbps.
  928. The following configurations can be forced.
  929. * Cable type: 40c, 80c, short40c, unk, ign or sata.
  930. Any ID with matching PORT is used.
  931. * SATA link speed limit: 1.5Gbps or 3.0Gbps.
  932. * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
  933. udma[/][16,25,33,44,66,100,133] notation is also
  934. allowed.
  935. * [no]ncq: Turn on or off NCQ.
  936. * nohrst, nosrst, norst: suppress hard, soft
  937. and both resets.
  938. If there are multiple matching configurations changing
  939. the same attribute, the last one is used.
  940. lmb=debug [KNL] Enable lmb debug messages.
  941. load_ramdisk= [RAM] List of ramdisks to load from floppy
  942. See Documentation/blockdev/ramdisk.txt.
  943. lockd.nlm_grace_period=P [NFS] Assign grace period.
  944. Format: <integer>
  945. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  946. Format: <integer>
  947. lockd.nlm_timeout=T [NFS] Assign timeout value.
  948. Format: <integer>
  949. lockd.nlm_udpport=M [NFS] Assign UDP port.
  950. Format: <integer>
  951. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  952. Format: <irq>
  953. loglevel= All Kernel Messages with a loglevel smaller than the
  954. console loglevel will be printed to the console. It can
  955. also be changed with klogd or other programs. The
  956. loglevels are defined as follows:
  957. 0 (KERN_EMERG) system is unusable
  958. 1 (KERN_ALERT) action must be taken immediately
  959. 2 (KERN_CRIT) critical conditions
  960. 3 (KERN_ERR) error conditions
  961. 4 (KERN_WARNING) warning conditions
  962. 5 (KERN_NOTICE) normal but significant condition
  963. 6 (KERN_INFO) informational
  964. 7 (KERN_DEBUG) debug-level messages
  965. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  966. Format: { n | nk | nM }
  967. n must be a power of two. The default size
  968. is set in the kernel config file.
  969. logo.nologo [FB] Disables display of the built-in Linux logo.
  970. This may be used to provide more screen space for
  971. kernel log messages and is useful when debugging
  972. kernel boot problems.
  973. lp=0 [LP] Specify parallel ports to use, e.g,
  974. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  975. lp=reset first parallel port). 'lp=0' disables the
  976. lp=auto printer driver. 'lp=reset' (which can be
  977. specified in addition to the ports) causes
  978. attached printers to be reset. Using
  979. lp=port1,port2,... specifies the parallel ports
  980. to associate lp devices with, starting with
  981. lp0. A port specification may be 'none' to skip
  982. that lp device, or a parport name such as
  983. 'parport0'. Specifying 'lp=auto' instead of a
  984. port specification list means that device IDs
  985. from each port should be examined, to see if
  986. an IEEE 1284-compliant printer is attached; if
  987. so, the driver will manage that printer.
  988. See also header of drivers/char/lp.c.
  989. lpj=n [KNL]
  990. Sets loops_per_jiffy to given constant, thus avoiding
  991. time-consuming boot-time autodetection (up to 250 ms per
  992. CPU). 0 enables autodetection (default). To determine
  993. the correct value for your kernel, boot with normal
  994. autodetection and see what value is printed. Note that
  995. on SMP systems the preset will be applied to all CPUs,
  996. which is likely to cause problems if your CPUs need
  997. significantly divergent settings. An incorrect value
  998. will cause delays in the kernel to be wrong, leading to
  999. unpredictable I/O errors and other breakage. Although
  1000. unlikely, in the extreme case this might damage your
  1001. hardware.
  1002. ltpc= [NET]
  1003. Format: <io>,<irq>,<dma>
  1004. mac5380= [HW,SCSI] Format:
  1005. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  1006. machvec= [IA64] Force the use of a particular machine-vector
  1007. (machvec) in a generic kernel.
  1008. Example: machvec=hpzx1_swiotlb
  1009. max_loop= [LOOP] Maximum number of loopback devices that can
  1010. be mounted
  1011. Format: <1-256>
  1012. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  1013. should make use of. maxcpus=n : n >= 0 limits the
  1014. kernel to using 'n' processors. n=0 is a special case,
  1015. it is equivalent to "nosmp", which also disables
  1016. the IO APIC.
  1017. max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
  1018. or equal to this physical address is ignored.
  1019. max_luns= [SCSI] Maximum number of LUNs to probe.
  1020. Should be between 1 and 2^32-1.
  1021. max_report_luns=
  1022. [SCSI] Maximum number of LUNs received.
  1023. Should be between 1 and 16384.
  1024. mcatest= [IA-64]
  1025. mce [X86-32] Machine Check Exception
  1026. mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
  1027. md= [HW] RAID subsystems devices and level
  1028. See Documentation/md.txt.
  1029. mdacon= [MDA]
  1030. Format: <first>,<last>
  1031. Specifies range of consoles to be captured by the MDA.
  1032. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  1033. Amount of memory to be used when the kernel is not able
  1034. to see the whole system memory or for test.
  1035. [X86-32] Use together with memmap= to avoid physical
  1036. address space collisions. Without memmap= PCI devices
  1037. could be placed at addresses belonging to unused RAM.
  1038. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  1039. memory.
  1040. memchunk=nn[KMG]
  1041. [KNL,SH] Allow user to override the default size for
  1042. per-device physically contiguous DMA buffers.
  1043. memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
  1044. E820 memory map, as specified by the user.
  1045. Such memmap=exactmap lines can be constructed based on
  1046. BIOS output or other requirements. See the memmap=nn@ss
  1047. option description.
  1048. memmap=nn[KMG]@ss[KMG]
  1049. [KNL] Force usage of a specific region of memory
  1050. Region of memory to be used, from ss to ss+nn.
  1051. memmap=nn[KMG]#ss[KMG]
  1052. [KNL,ACPI] Mark specific memory as ACPI data.
  1053. Region of memory to be used, from ss to ss+nn.
  1054. memmap=nn[KMG]$ss[KMG]
  1055. [KNL,ACPI] Mark specific memory as reserved.
  1056. Region of memory to be used, from ss to ss+nn.
  1057. Example: Exclude memory from 0x18690000-0x1869ffff
  1058. memmap=64K$0x18690000
  1059. or
  1060. memmap=0x10000$0x18690000
  1061. memory_corruption_check=0/1 [X86]
  1062. Some BIOSes seem to corrupt the first 64k of
  1063. memory when doing things like suspend/resume.
  1064. Setting this option will scan the memory
  1065. looking for corruption. Enabling this will
  1066. both detect corruption and prevent the kernel
  1067. from using the memory being corrupted.
  1068. However, its intended as a diagnostic tool; if
  1069. repeatable BIOS-originated corruption always
  1070. affects the same memory, you can use memmap=
  1071. to prevent the kernel from using that memory.
  1072. memory_corruption_check_size=size [X86]
  1073. By default it checks for corruption in the low
  1074. 64k, making this memory unavailable for normal
  1075. use. Use this parameter to scan for
  1076. corruption in more or less memory.
  1077. memory_corruption_check_period=seconds [X86]
  1078. By default it checks for corruption every 60
  1079. seconds. Use this parameter to check at some
  1080. other rate. 0 disables periodic checking.
  1081. memtest= [KNL,X86] Enable memtest
  1082. Format: <integer>
  1083. default : 0 <disable>
  1084. Specifies the number of memtest passes to be
  1085. performed. Each pass selects another test
  1086. pattern from a given set of patterns. Memtest
  1087. fills the memory with this pattern, validates
  1088. memory contents and reserves bad memory
  1089. regions that are detected.
  1090. meye.*= [HW] Set MotionEye Camera parameters
  1091. See Documentation/video4linux/meye.txt.
  1092. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  1093. Multi-Function General Purpose Timers on AMD Geode
  1094. platforms.
  1095. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  1096. the BIOS has incorrectly applied a workaround. TinyBIOS
  1097. version 0.98 is known to be affected, 0.99 fixes the
  1098. problem by letting the user disable the workaround.
  1099. mga= [HW,DRM]
  1100. min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
  1101. physical address is ignored.
  1102. mminit_loglevel=
  1103. [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
  1104. parameter allows control of the logging verbosity for
  1105. the additional memory initialisation checks. A value
  1106. of 0 disables mminit logging and a level of 4 will
  1107. log everything. Information is printed at KERN_DEBUG
  1108. so loglevel=8 may also need to be specified.
  1109. mousedev.tap_time=
  1110. [MOUSE] Maximum time between finger touching and
  1111. leaving touchpad surface for touch to be considered
  1112. a tap and be reported as a left button click (for
  1113. touchpads working in absolute mode only).
  1114. Format: <msecs>
  1115. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  1116. reporting absolute coordinates, such as tablets
  1117. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  1118. reporting absolute coordinates, such as tablets
  1119. mpu401= [HW,OSS]
  1120. Format: <io>,<irq>
  1121. MTD_Partition= [MTD]
  1122. Format: <name>,<region-number>,<size>,<offset>
  1123. MTD_Region= [MTD] Format:
  1124. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  1125. mtdparts= [MTD]
  1126. See drivers/mtd/cmdlinepart.c.
  1127. mtdset= [ARM]
  1128. ARM/S3C2412 JIVE boot control
  1129. See arch/arm/mach-s3c2412/mach-jive.c
  1130. mtouchusb.raw_coordinates=
  1131. [HW] Make the MicroTouch USB driver use raw coordinates
  1132. ('y', default) or cooked coordinates ('n')
  1133. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  1134. NCR_D700= [HW,SCSI]
  1135. See header of drivers/scsi/NCR_D700.c.
  1136. ncr5380= [HW,SCSI]
  1137. ncr53c400= [HW,SCSI]
  1138. ncr53c400a= [HW,SCSI]
  1139. ncr53c406a= [HW,SCSI]
  1140. ncr53c8xx= [HW,SCSI]
  1141. netdev= [NET] Network devices parameters
  1142. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  1143. Note that mem_start is often overloaded to mean
  1144. something different and driver-specific.
  1145. This usage is only documented in each driver source
  1146. file if at all.
  1147. nf_conntrack.acct=
  1148. [NETFILTER] Enable connection tracking flow accounting
  1149. 0 to disable accounting
  1150. 1 to enable accounting
  1151. Default value depends on CONFIG_NF_CT_ACCT that is
  1152. going to be removed in 2.6.29.
  1153. nfsaddrs= [NFS]
  1154. See Documentation/filesystems/nfsroot.txt.
  1155. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  1156. See Documentation/filesystems/nfsroot.txt.
  1157. nfs.callback_tcpport=
  1158. [NFS] set the TCP port on which the NFSv4 callback
  1159. channel should listen.
  1160. nfs.idmap_cache_timeout=
  1161. [NFS] set the maximum lifetime for idmapper cache
  1162. entries.
  1163. nfs.enable_ino64=
  1164. [NFS] enable 64-bit inode numbers.
  1165. If zero, the NFS client will fake up a 32-bit inode
  1166. number for the readdir() and stat() syscalls instead
  1167. of returning the full 64-bit number.
  1168. The default is to return 64-bit inode numbers.
  1169. nmi_debug= [KNL,AVR32] Specify one or more actions to take
  1170. when a NMI is triggered.
  1171. Format: [state][,regs][,debounce][,die]
  1172. nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
  1173. Format: [panic,][num]
  1174. Valid num: 0,1,2
  1175. 0 - turn nmi_watchdog off
  1176. 1 - use the IO-APIC timer for the NMI watchdog
  1177. 2 - use the local APIC for the NMI watchdog using
  1178. a performance counter. Note: This will use one performance
  1179. counter and the local APIC's performance vector.
  1180. When panic is specified panic when an NMI watchdog timeout occurs.
  1181. This is useful when you use a panic=... timeout and need the box
  1182. quickly up again.
  1183. Instead of 1 and 2 it is possible to use the following
  1184. symbolic names: lapic and ioapic
  1185. Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
  1186. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  1187. emulation library even if a 387 maths coprocessor
  1188. is present.
  1189. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  1190. caches in the slab allocator. Saves per-node memory,
  1191. but will impact performance.
  1192. noalign [KNL,ARM]
  1193. noapic [SMP,APIC] Tells the kernel to not make use of any
  1194. IOAPICs that may be present in the system.
  1195. nobats [PPC] Do not use BATs for mapping kernel lowmem
  1196. on "Classic" PPC cores.
  1197. nocache [ARM]
  1198. nodelayacct [KNL] Disable per-task delay accounting
  1199. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  1200. nodsp [SH] Disable hardware DSP at boot time.
  1201. noefi [X86-32,X86-64] Disable EFI runtime services support.
  1202. noexec [IA-64]
  1203. noexec [X86-32,X86-64]
  1204. On X86-32 available only on PAE configured kernels.
  1205. noexec=on: enable non-executable mappings (default)
  1206. noexec=off: disable non-executable mappings
  1207. noexec32 [X86-64]
  1208. This affects only 32-bit executables.
  1209. noexec32=on: enable non-executable mappings (default)
  1210. read doesn't imply executable mappings
  1211. noexec32=off: disable non-executable mappings
  1212. read implies executable mappings
  1213. nofpu [SH] Disable hardware FPU at boot time.
  1214. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  1215. register save and restore. The kernel will only save
  1216. legacy floating-point registers on task switch.
  1217. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  1218. nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
  1219. wfi(ARM) instruction doesn't work correctly and not to
  1220. use it. This is also useful when using JTAG debugger.
  1221. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  1222. instruction doesn't work correctly and not to
  1223. use it.
  1224. no_file_caps Tells the kernel not to honor file capabilities. The
  1225. only way then for a file to be executed with privilege
  1226. is to be setuid root or executed by root.
  1227. nohalt [IA-64] Tells the kernel not to use the power saving
  1228. function PAL_HALT_LIGHT when idle. This increases
  1229. power-consumption. On the positive side, it reduces
  1230. interrupt wake-up latency, which may improve performance
  1231. in certain environments such as networked servers or
  1232. real-time systems.
  1233. nohz= [KNL] Boottime enable/disable dynamic ticks
  1234. Valid arguments: on, off
  1235. Default: on
  1236. noirqdebug [X86-32] Disables the code which attempts to detect and
  1237. disable unhandled interrupt sources.
  1238. no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
  1239. broken timer IRQ sources.
  1240. noisapnp [ISAPNP] Disables ISA PnP code.
  1241. noinitrd [RAM] Tells the kernel not to load any configured
  1242. initial RAM disk.
  1243. nointroute [IA-64]
  1244. nojitter [IA64] Disables jitter checking for ITC timers.
  1245. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  1246. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  1247. nox2apic [X86-64,APIC] Do not enable x2APIC mode.
  1248. x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
  1249. default x2apic cluster mode on platforms
  1250. supporting x2apic.
  1251. noltlbs [PPC] Do not use large page/tlb entries for kernel
  1252. lowmem mapping on PPC40x.
  1253. nomca [IA-64] Disable machine check abort handling
  1254. nomce [X86-32] Machine Check Exception
  1255. nomfgpt [X86-32] Disable Multi-Function General Purpose
  1256. Timer usage (for AMD Geode machines).
  1257. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  1258. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1259. with UP alternatives
  1260. noresidual [PPC] Don't use residual data on PReP machines.
  1261. noresume [SWSUSP] Disables resume and restores original swap
  1262. space.
  1263. no-scroll [VGA] Disables scrollback.
  1264. This is required for the Braillex ib80-piezo Braille
  1265. reader made by F.H. Papenmeier (Germany).
  1266. nosbagart [IA-64]
  1267. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1268. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1269. and disable the IO APIC. legacy for "maxcpus=0".
  1270. nosoftlockup [KNL] Disable the soft-lockup detector.
  1271. noswapaccount [KNL] Disable accounting of swap in memory resource
  1272. controller. (See Documentation/controllers/memory.txt)
  1273. nosync [HW,M68K] Disables sync negotiation for all devices.
  1274. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1275. nousb [USB] Disable the USB subsystem
  1276. nowb [ARM]
  1277. nptcg= [IA64] Override max number of concurrent global TLB
  1278. purges which is reported from either PAL_VM_SUMMARY or
  1279. SAL PALO.
  1280. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1281. one of ['zone', 'node', 'default'] can be specified
  1282. This can be set from sysctl after boot.
  1283. See Documentation/sysctl/vm.txt for details.
  1284. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1285. ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
  1286. See Documentation/debugging-via-ohci1394.txt for more
  1287. info.
  1288. olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
  1289. Rather than timing out after 20 ms if an EC
  1290. command is not properly ACKed, override the length
  1291. of the timeout. We have interrupts disabled while
  1292. waiting for the ACK, so if this is set too high
  1293. interrupts *may* be lost!
  1294. opl3= [HW,OSS]
  1295. Format: <io>
  1296. oprofile.timer= [HW]
  1297. Use timer interrupt instead of performance counters
  1298. osst= [HW,SCSI] SCSI Tape Driver
  1299. Format: <buffer_size>,<write_threshold>
  1300. See also Documentation/scsi/st.txt.
  1301. panic= [KNL] Kernel behaviour on panic
  1302. Format: <timeout>
  1303. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1304. connected to, default is 0.
  1305. Format: <parport#>
  1306. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1307. 0 for XT, 1 for AT (default is AT).
  1308. Format: <mode>
  1309. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1310. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1311. Use 'auto' to force the driver to use any
  1312. IRQ/DMA settings detected (the default is to
  1313. ignore detected IRQ/DMA settings because of
  1314. possible conflicts). You can specify the base
  1315. address, IRQ, and DMA settings; IRQ and DMA
  1316. should be numbers, or 'auto' (for using detected
  1317. settings on that particular port), or 'nofifo'
  1318. (to avoid using a FIFO even if it is detected).
  1319. Parallel ports are assigned in the order they
  1320. are specified on the command line, starting
  1321. with parport0.
  1322. parport_init_mode= [HW,PPT]
  1323. Configure VIA parallel port to operate in
  1324. a specific mode. This is necessary on Pegasos
  1325. computer where firmware has no options for setting
  1326. up parallel port mode and sets it to spp.
  1327. Currently this function knows 686a and 8231 chips.
  1328. Format: [spp|ps2|epp|ecp|ecpepp]
  1329. pas2= [HW,OSS] Format:
  1330. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1331. pas16= [HW,SCSI]
  1332. See header of drivers/scsi/pas16.c.
  1333. pause_on_oops=
  1334. Halt all CPUs after the first oops has been printed for
  1335. the specified number of seconds. This is to be used if
  1336. your oopses keep scrolling off the screen.
  1337. pcbit= [HW,ISDN]
  1338. pcd. [PARIDE]
  1339. See header of drivers/block/paride/pcd.c.
  1340. See also Documentation/blockdev/paride.txt.
  1341. pci=option[,option...] [PCI] various PCI subsystem options:
  1342. earlydump [X86] dump PCI config space before the kernel
  1343. changes anything
  1344. off [X86] don't probe for the PCI bus
  1345. bios [X86-32] force use of PCI BIOS, don't access
  1346. the hardware directly. Use this if your machine
  1347. has a non-standard PCI host bridge.
  1348. nobios [X86-32] disallow use of PCI BIOS, only direct
  1349. hardware access methods are allowed. Use this
  1350. if you experience crashes upon bootup and you
  1351. suspect they are caused by the BIOS.
  1352. conf1 [X86] Force use of PCI Configuration
  1353. Mechanism 1.
  1354. conf2 [X86] Force use of PCI Configuration
  1355. Mechanism 2.
  1356. noaer [PCIE] If the PCIEAER kernel config parameter is
  1357. enabled, this kernel boot option can be used to
  1358. disable the use of PCIE advanced error reporting.
  1359. nodomains [PCI] Disable support for multiple PCI
  1360. root domains (aka PCI segments, in ACPI-speak).
  1361. nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
  1362. Configuration
  1363. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1364. enabled, this kernel boot option can be used to
  1365. disable the use of MSI interrupts system-wide.
  1366. noioapicquirk [APIC] Disable all boot interrupt quirks.
  1367. Safety option to keep boot IRQs enabled. This
  1368. should never be necessary.
  1369. ioapicreroute [APIC] Enable rerouting of boot IRQs to the
  1370. primary IO-APIC for bridges that cannot disable
  1371. boot IRQs. This fixes a source of spurious IRQs
  1372. when the system masks IRQs.
  1373. noioapicreroute [APIC] Disable workaround that uses the
  1374. boot IRQ equivalent of an IRQ that connects to
  1375. a chipset where boot IRQs cannot be disabled.
  1376. The opposite of ioapicreroute.
  1377. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1378. routing table. These calls are known to be buggy
  1379. on several machines and they hang the machine
  1380. when used, but on other computers it's the only
  1381. way to get the interrupt routing table. Try
  1382. this option if the kernel is unable to allocate
  1383. IRQs or discover secondary PCI buses on your
  1384. motherboard.
  1385. rom [X86] Assign address space to expansion ROMs.
  1386. Use with caution as certain devices share
  1387. address decoders between ROMs and other
  1388. resources.
  1389. norom [X86] Do not assign address space to
  1390. expansion ROMs that do not already have
  1391. BIOS assigned address ranges.
  1392. irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
  1393. assigned automatically to PCI devices. You can
  1394. make the kernel exclude IRQs of your ISA cards
  1395. this way.
  1396. pirqaddr=0xAAAAA [X86] Specify the physical address
  1397. of the PIRQ table (normally generated
  1398. by the BIOS) if it is outside the
  1399. F0000h-100000h range.
  1400. lastbus=N [X86] Scan all buses thru bus #N. Can be
  1401. useful if the kernel is unable to find your
  1402. secondary buses and you want to tell it
  1403. explicitly which ones they are.
  1404. assign-busses [X86] Always assign all PCI bus
  1405. numbers ourselves, overriding
  1406. whatever the firmware may have done.
  1407. usepirqmask [X86] Honor the possible IRQ mask stored
  1408. in the BIOS $PIR table. This is needed on
  1409. some systems with broken BIOSes, notably
  1410. some HP Pavilion N5400 and Omnibook XE3
  1411. notebooks. This will have no effect if ACPI
  1412. IRQ routing is enabled.
  1413. noacpi [X86] Do not use ACPI for IRQ routing
  1414. or for PCI scanning.
  1415. use_crs [X86] Use _CRS for PCI resource
  1416. allocation.
  1417. routeirq Do IRQ routing for all PCI devices.
  1418. This is normally done in pci_enable_device(),
  1419. so this option is a temporary workaround
  1420. for broken drivers that don't call it.
  1421. skip_isa_align [X86] do not align io start addr, so can
  1422. handle more pci cards
  1423. firmware [ARM] Do not re-enumerate the bus but instead
  1424. just use the configuration from the
  1425. bootloader. This is currently used on
  1426. IXP2000 systems where the bus has to be
  1427. configured a certain way for adjunct CPUs.
  1428. noearly [X86] Don't do any early type 1 scanning.
  1429. This might help on some broken boards which
  1430. machine check when some devices' config space
  1431. is read. But various workarounds are disabled
  1432. and some IOMMU drivers will not work.
  1433. bfsort Sort PCI devices into breadth-first order.
  1434. This sorting is done to get a device
  1435. order compatible with older (<= 2.4) kernels.
  1436. nobfsort Don't sort PCI devices into breadth-first order.
  1437. cbiosize=nn[KMG] The fixed amount of bus space which is
  1438. reserved for the CardBus bridge's IO window.
  1439. The default value is 256 bytes.
  1440. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1441. reserved for the CardBus bridge's memory
  1442. window. The default value is 64 megabytes.
  1443. resource_alignment=
  1444. Format:
  1445. [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
  1446. Specifies alignment and device to reassign
  1447. aligned memory resources.
  1448. If <order of align> is not specified,
  1449. PAGE_SIZE is used as alignment.
  1450. PCI-PCI bridge can be specified, if resource
  1451. windows need to be expanded.
  1452. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
  1453. Management.
  1454. off Disable ASPM.
  1455. force Enable ASPM even on devices that claim not to support it.
  1456. WARNING: Forcing ASPM on may cause system lockups.
  1457. pcmv= [HW,PCMCIA] BadgePAD 4
  1458. pd. [PARIDE]
  1459. See Documentation/blockdev/paride.txt.
  1460. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1461. boot time.
  1462. Format: { 0 | 1 }
  1463. See arch/parisc/kernel/pdc_chassis.c
  1464. pf. [PARIDE]
  1465. See Documentation/blockdev/paride.txt.
  1466. pg. [PARIDE]
  1467. See Documentation/blockdev/paride.txt.
  1468. pirq= [SMP,APIC] Manual mp-table setup
  1469. See Documentation/x86/i386/IO-APIC.txt.
  1470. plip= [PPT,NET] Parallel port network link
  1471. Format: { parport<nr> | timid | 0 }
  1472. See also Documentation/parport.txt.
  1473. pmtmr= [X86] Manual setup of pmtmr I/O Port.
  1474. Override pmtimer IOPort with a hex value.
  1475. e.g. pmtmr=0x508
  1476. pnp.debug [PNP]
  1477. Enable PNP debug messages. This depends on the
  1478. CONFIG_PNP_DEBUG_MESSAGES option.
  1479. pnpacpi= [ACPI]
  1480. { off }
  1481. pnpbios= [ISAPNP]
  1482. { on | off | curr | res | no-curr | no-res }
  1483. pnp_reserve_irq=
  1484. [ISAPNP] Exclude IRQs for the autoconfiguration
  1485. pnp_reserve_dma=
  1486. [ISAPNP] Exclude DMAs for the autoconfiguration
  1487. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1488. Ranges are in pairs (I/O port base and size).
  1489. pnp_reserve_mem=
  1490. [ISAPNP] Exclude memory regions for the
  1491. autoconfiguration.
  1492. Ranges are in pairs (memory base and size).
  1493. print-fatal-signals=
  1494. [KNL] debug: print fatal signals
  1495. print-fatal-signals=1: print segfault info to
  1496. the kernel console.
  1497. default: off.
  1498. printk.time= Show timing data prefixed to each printk message line
  1499. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1500. profile= [KNL] Enable kernel profiling via /proc/profile
  1501. Format: [schedule,]<number>
  1502. Param: "schedule" - profile schedule points.
  1503. Param: <number> - step/bucket size as a power of 2 for
  1504. statistical time based profiling.
  1505. Param: "sleep" - profile D-state sleeping (millisecs).
  1506. Requires CONFIG_SCHEDSTATS
  1507. Param: "kvm" - profile VM exits.
  1508. processor.max_cstate= [HW,ACPI]
  1509. Limit processor to maximum C-state
  1510. max_cstate=9 overrides any DMI blacklist limit.
  1511. processor.nocst [HW,ACPI]
  1512. Ignore the _CST method to determine C-states,
  1513. instead using the legacy FADT method
  1514. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1515. before loading.
  1516. See Documentation/blockdev/ramdisk.txt.
  1517. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1518. probe for; one of (bare|imps|exps|lifebook|any).
  1519. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1520. per second.
  1521. psmouse.resetafter= [HW,MOUSE]
  1522. Try to reset the device after so many bad packets
  1523. (0 = never).
  1524. psmouse.resolution=
  1525. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1526. psmouse.smartscroll=
  1527. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1528. 0 = disabled, 1 = enabled (default).
  1529. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1530. Format:
  1531. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1532. pt. [PARIDE]
  1533. See Documentation/blockdev/paride.txt.
  1534. pty.legacy_count=
  1535. [KNL] Number of legacy pty's. Overwrites compiled-in
  1536. default number.
  1537. quiet [KNL] Disable most log messages
  1538. r128= [HW,DRM]
  1539. raid= [HW,RAID]
  1540. See Documentation/md.txt.
  1541. ramdisk_blocksize= [RAM]
  1542. See Documentation/blockdev/ramdisk.txt.
  1543. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1544. See Documentation/blockdev/ramdisk.txt.
  1545. rcupdate.blimit= [KNL,BOOT]
  1546. Set maximum number of finished RCU callbacks to process
  1547. in one batch.
  1548. rcupdate.qhimark= [KNL,BOOT]
  1549. Set threshold of queued
  1550. RCU callbacks over which batch limiting is disabled.
  1551. rcupdate.qlowmark= [KNL,BOOT]
  1552. Set threshold of queued RCU callbacks below which
  1553. batch limiting is re-enabled.
  1554. rdinit= [KNL]
  1555. Format: <full_path>
  1556. Run specified binary instead of /init from the ramdisk,
  1557. used for early userspace startup. See initrd.
  1558. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1559. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1560. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1561. relax_domain_level=
  1562. [KNL, SMP] Set scheduler's default relax_domain_level.
  1563. See Documentation/cpusets.txt.
  1564. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1565. reservetop= [X86-32]
  1566. Format: nn[KMG]
  1567. Reserves a hole at the top of the kernel virtual
  1568. address space.
  1569. reset_devices [KNL] Force drivers to reset the underlying device
  1570. during initialization.
  1571. resume= [SWSUSP]
  1572. Specify the partition device for software suspend
  1573. resume_offset= [SWSUSP]
  1574. Specify the offset from the beginning of the partition
  1575. given by "resume=" at which the swap header is located,
  1576. in <PAGE_SIZE> units (needed only for swap files).
  1577. See Documentation/power/swsusp-and-swap-files.txt
  1578. retain_initrd [RAM] Keep initrd memory after extraction
  1579. rhash_entries= [KNL,NET]
  1580. Set number of hash buckets for route cache
  1581. riscom8= [HW,SERIAL]
  1582. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1583. ro [KNL] Mount root device read-only on boot
  1584. root= [KNL] Root filesystem
  1585. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1586. mount the root filesystem
  1587. rootflags= [KNL] Set root filesystem mount option string
  1588. rootfstype= [KNL] Set root filesystem type
  1589. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1590. Useful for devices that are detected asynchronously
  1591. (e.g. USB and MMC devices).
  1592. root_plug.vendor_id=
  1593. [ROOTPLUG] Override the default vendor ID
  1594. root_plug.product_id=
  1595. [ROOTPLUG] Override the default product ID
  1596. root_plug.debug=
  1597. [ROOTPLUG] Enable debugging output
  1598. rw [KNL] Mount root device read-write on boot
  1599. S [KNL] Run init in single mode
  1600. sa1100ir [NET]
  1601. See drivers/net/irda/sa1100_ir.c.
  1602. sbni= [NET] Granch SBNI12 leased line adapter
  1603. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1604. Format: <io>[,<timeout>[,<isapnp>]]
  1605. scsi_debug_*= [SCSI]
  1606. See drivers/scsi/scsi_debug.c.
  1607. scsi_default_dev_flags=
  1608. [SCSI] SCSI default device flags
  1609. Format: <integer>
  1610. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1611. Format: <vendor>:<model>:<flags>
  1612. (flags are integer value)
  1613. scsi_logging_level= [SCSI] a bit mask of logging levels
  1614. See drivers/scsi/scsi_logging.h for bits. Also
  1615. settable via sysctl at dev.scsi.logging_level
  1616. (/proc/sys/dev/scsi/logging_level).
  1617. There is also a nice 'scsi_logging_level' script in the
  1618. S390-tools package, available for download at
  1619. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1620. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1621. discovered. async scans them in kernel threads,
  1622. allowing boot to proceed. none ignores them, expecting
  1623. user space to do the scan.
  1624. selinux [SELINUX] Disable or enable SELinux at boot time.
  1625. Format: { "0" | "1" }
  1626. See security/selinux/Kconfig help text.
  1627. 0 -- disable.
  1628. 1 -- enable.
  1629. Default value is set via kernel config option.
  1630. If enabled at boot time, /selinux/disable can be used
  1631. later to disable prior to initial policy load.
  1632. serialnumber [BUGS=X86-32]
  1633. shapers= [NET]
  1634. Maximal number of shapers.
  1635. show_msr= [x86] show boot-time MSR settings
  1636. Format: { <integer> }
  1637. Show boot-time (BIOS-initialized) MSR settings.
  1638. The parameter means the number of CPUs to show,
  1639. for example 1 means boot CPU only.
  1640. sim710= [SCSI,HW]
  1641. See header of drivers/scsi/sim710.c.
  1642. simeth= [IA-64]
  1643. simscsi=
  1644. slram= [HW,MTD]
  1645. slub_debug[=options[,slabs]] [MM, SLUB]
  1646. Enabling slub_debug allows one to determine the
  1647. culprit if slab objects become corrupted. Enabling
  1648. slub_debug can create guard zones around objects and
  1649. may poison objects when not in use. Also tracks the
  1650. last alloc / free. For more information see
  1651. Documentation/vm/slub.txt.
  1652. slub_max_order= [MM, SLUB]
  1653. Determines the maximum allowed order for slabs.
  1654. A high setting may cause OOMs due to memory
  1655. fragmentation. For more information see
  1656. Documentation/vm/slub.txt.
  1657. slub_min_objects= [MM, SLUB]
  1658. The minimum number of objects per slab. SLUB will
  1659. increase the slab order up to slub_max_order to
  1660. generate a sufficiently large slab able to contain
  1661. the number of objects indicated. The higher the number
  1662. of objects the smaller the overhead of tracking slabs
  1663. and the less frequently locks need to be acquired.
  1664. For more information see Documentation/vm/slub.txt.
  1665. slub_min_order= [MM, SLUB]
  1666. Determines the mininum page order for slabs. Must be
  1667. lower than slub_max_order.
  1668. For more information see Documentation/vm/slub.txt.
  1669. slub_nomerge [MM, SLUB]
  1670. Disable merging of slabs with similar size. May be
  1671. necessary if there is some reason to distinguish
  1672. allocs to different slabs. Debug options disable
  1673. merging on their own.
  1674. For more information see Documentation/vm/slub.txt.
  1675. smart2= [HW]
  1676. Format: <io1>[,<io2>[,...,<io8>]]
  1677. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1678. attempt to substitute SMP alternatives once at boot.
  1679. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1680. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1681. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1682. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1683. smsc-ircc2.ircc_irq= [HW] IRQ line
  1684. smsc-ircc2.ircc_dma= [HW] DMA channel
  1685. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1686. 0: Toshiba Satellite 1800 (GP data pin select)
  1687. 1: Fast pin select (default)
  1688. 2: ATC IRMode
  1689. snd-ad1816a= [HW,ALSA]
  1690. snd-ad1848= [HW,ALSA]
  1691. snd-ali5451= [HW,ALSA]
  1692. snd-als100= [HW,ALSA]
  1693. snd-als4000= [HW,ALSA]
  1694. snd-azt2320= [HW,ALSA]
  1695. snd-cmi8330= [HW,ALSA]
  1696. snd-cmipci= [HW,ALSA]
  1697. snd-cs4231= [HW,ALSA]
  1698. snd-cs4232= [HW,ALSA]
  1699. snd-cs4236= [HW,ALSA]
  1700. snd-cs4281= [HW,ALSA]
  1701. snd-cs46xx= [HW,ALSA]
  1702. snd-dt019x= [HW,ALSA]
  1703. snd-dummy= [HW,ALSA]
  1704. snd-emu10k1= [HW,ALSA]
  1705. snd-ens1370= [HW,ALSA]
  1706. snd-ens1371= [HW,ALSA]
  1707. snd-es968= [HW,ALSA]
  1708. snd-es1688= [HW,ALSA]
  1709. snd-es18xx= [HW,ALSA]
  1710. snd-es1938= [HW,ALSA]
  1711. snd-es1968= [HW,ALSA]
  1712. snd-fm801= [HW,ALSA]
  1713. snd-gusclassic= [HW,ALSA]
  1714. snd-gusextreme= [HW,ALSA]
  1715. snd-gusmax= [HW,ALSA]
  1716. snd-hdsp= [HW,ALSA]
  1717. snd-ice1712= [HW,ALSA]
  1718. snd-intel8x0= [HW,ALSA]
  1719. snd-interwave= [HW,ALSA]
  1720. snd-interwave-stb=
  1721. [HW,ALSA]
  1722. snd-korg1212= [HW,ALSA]
  1723. snd-maestro3= [HW,ALSA]
  1724. snd-mpu401= [HW,ALSA]
  1725. snd-mtpav= [HW,ALSA]
  1726. snd-nm256= [HW,ALSA]
  1727. snd-opl3sa2= [HW,ALSA]
  1728. snd-opti92x-ad1848=
  1729. [HW,ALSA]
  1730. snd-opti92x-cs4231=
  1731. [HW,ALSA]
  1732. snd-opti93x= [HW,ALSA]
  1733. snd-pmac= [HW,ALSA]
  1734. snd-rme32= [HW,ALSA]
  1735. snd-rme96= [HW,ALSA]
  1736. snd-rme9652= [HW,ALSA]
  1737. snd-sb8= [HW,ALSA]
  1738. snd-sb16= [HW,ALSA]
  1739. snd-sbawe= [HW,ALSA]
  1740. snd-serial= [HW,ALSA]
  1741. snd-sgalaxy= [HW,ALSA]
  1742. snd-sonicvibes= [HW,ALSA]
  1743. snd-sun-amd7930=
  1744. [HW,ALSA]
  1745. snd-sun-cs4231= [HW,ALSA]
  1746. snd-trident= [HW,ALSA]
  1747. snd-usb-audio= [HW,ALSA,USB]
  1748. snd-via82xx= [HW,ALSA]
  1749. snd-virmidi= [HW,ALSA]
  1750. snd-wavefront= [HW,ALSA]
  1751. snd-ymfpci= [HW,ALSA]
  1752. softlockup_panic=
  1753. [KNL] Should the soft-lockup detector generate panics.
  1754. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1755. See Documentation/sonypi.txt
  1756. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1757. See Documentation/serial/specialix.txt.
  1758. spia_io_base= [HW,MTD]
  1759. spia_fio_base=
  1760. spia_pedr=
  1761. spia_peddr=
  1762. sscape= [HW,OSS]
  1763. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1764. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1765. See Documentation/scsi/st.txt.
  1766. stacktrace [FTRACE]
  1767. Enabled the stack tracer on boot up.
  1768. sti= [PARISC,HW]
  1769. Format: <num>
  1770. Set the STI (builtin display/keyboard on the HP-PARISC
  1771. machines) console (graphic card) which should be used
  1772. as the initial boot-console.
  1773. See also comment in drivers/video/console/sticore.c.
  1774. sti_font= [HW]
  1775. See comment in drivers/video/console/sticore.c.
  1776. stifb= [HW]
  1777. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1778. sunrpc.pool_mode=
  1779. [NFS]
  1780. Control how the NFS server code allocates CPUs to
  1781. service thread pools. Depending on how many NICs
  1782. you have and where their interrupts are bound, this
  1783. option will affect which CPUs will do NFS serving.
  1784. Note: this parameter cannot be changed while the
  1785. NFS server is running.
  1786. auto the server chooses an appropriate mode
  1787. automatically using heuristics
  1788. global a single global pool contains all CPUs
  1789. percpu one pool for each CPU
  1790. pernode one pool for each NUMA node (equivalent
  1791. to global on non-NUMA machines)
  1792. swiotlb= [IA-64] Number of I/O TLB slabs
  1793. switches= [HW,M68k]
  1794. sym53c416= [HW,SCSI]
  1795. See header of drivers/scsi/sym53c416.c.
  1796. sysrq_always_enabled
  1797. [KNL]
  1798. Ignore sysrq setting - this boot parameter will
  1799. neutralize any effect of /proc/sys/kernel/sysrq.
  1800. Useful for debugging.
  1801. t128= [HW,SCSI]
  1802. See header of drivers/scsi/t128.c.
  1803. tdfx= [HW,DRM]
  1804. test_suspend= [SUSPEND]
  1805. Specify "mem" (for Suspend-to-RAM) or "standby" (for
  1806. standby suspend) as the system sleep state to briefly
  1807. enter during system startup. The system is woken from
  1808. this state using a wakeup-capable RTC alarm.
  1809. thash_entries= [KNL,NET]
  1810. Set number of hash buckets for TCP connection
  1811. thermal.act= [HW,ACPI]
  1812. -1: disable all active trip points in all thermal zones
  1813. <degrees C>: override all lowest active trip points
  1814. thermal.crt= [HW,ACPI]
  1815. -1: disable all critical trip points in all thermal zones
  1816. <degrees C>: override all critical trip points
  1817. thermal.nocrt= [HW,ACPI]
  1818. Set to disable actions on ACPI thermal zone
  1819. critical and hot trip points.
  1820. thermal.off= [HW,ACPI]
  1821. 1: disable ACPI thermal control
  1822. thermal.psv= [HW,ACPI]
  1823. -1: disable all passive trip points
  1824. <degrees C>: override all passive trip points to this
  1825. value
  1826. thermal.tzp= [HW,ACPI]
  1827. Specify global default ACPI thermal zone polling rate
  1828. <deci-seconds>: poll all this frequency
  1829. 0: no polling (default)
  1830. tmscsim= [HW,SCSI]
  1831. See comment before function dc390_setup() in
  1832. drivers/scsi/tmscsim.c.
  1833. topology= [S390]
  1834. Format: {off | on}
  1835. Specify if the kernel should make use of the cpu
  1836. topology informations if the hardware supports these.
  1837. The scheduler will make use of these informations and
  1838. e.g. base its process migration decisions on it.
  1839. Default is off.
  1840. tp720= [HW,PS2]
  1841. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1842. Format:
  1843. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1844. tsc= Disable clocksource-must-verify flag for TSC.
  1845. Format: <string>
  1846. [x86] reliable: mark tsc clocksource as reliable, this
  1847. disables clocksource verification at runtime.
  1848. Used to enable high-resolution timer mode on older
  1849. hardware, and in virtualized environment.
  1850. turbografx.map[2|3]= [HW,JOY]
  1851. TurboGraFX parallel port interface
  1852. Format:
  1853. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1854. See also Documentation/input/joystick-parport.txt
  1855. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1856. See header of drivers/scsi/u14-34f.c.
  1857. uart401= [HW,OSS]
  1858. Format: <io>,<irq>
  1859. uart6850= [HW,OSS]
  1860. Format: <io>,<irq>
  1861. uhci-hcd.ignore_oc=
  1862. [USB] Ignore overcurrent events (default N).
  1863. Some badly-designed motherboards generate lots of
  1864. bogus events, for ports that aren't wired to
  1865. anything. Set this parameter to avoid log spamming.
  1866. Note that genuine overcurrent events won't be
  1867. reported either.
  1868. unknown_nmi_panic
  1869. [X86-32,X86-64]
  1870. Set unknown_nmi_panic=1 early on boot.
  1871. usbcore.autosuspend=
  1872. [USB] The autosuspend time delay (in seconds) used
  1873. for newly-detected USB devices (default 2). This
  1874. is the time required before an idle device will be
  1875. autosuspended. Devices for which the delay is set
  1876. to a negative value won't be autosuspended at all.
  1877. usbcore.usbfs_snoop=
  1878. [USB] Set to log all usbfs traffic (default 0 = off).
  1879. usbcore.blinkenlights=
  1880. [USB] Set to cycle leds on hubs (default 0 = off).
  1881. usbcore.old_scheme_first=
  1882. [USB] Start with the old device initialization
  1883. scheme (default 0 = off).
  1884. usbcore.use_both_schemes=
  1885. [USB] Try the other device initialization scheme
  1886. if the first one fails (default 1 = enabled).
  1887. usbcore.initial_descriptor_timeout=
  1888. [USB] Specifies timeout for the initial 64-byte
  1889. USB_REQ_GET_DESCRIPTOR request in milliseconds
  1890. (default 5000 = 5.0 seconds).
  1891. usbhid.mousepoll=
  1892. [USBHID] The interval which mice are to be polled at.
  1893. usb-storage.delay_use=
  1894. [UMS] The delay in seconds before a new device is
  1895. scanned for Logical Units (default 5).
  1896. usb-storage.quirks=
  1897. [UMS] A list of quirks entries to supplement or
  1898. override the built-in unusual_devs list. List
  1899. entries are separated by commas. Each entry has
  1900. the form VID:PID:Flags where VID and PID are Vendor
  1901. and Product ID values (4-digit hex numbers) and
  1902. Flags is a set of characters, each corresponding
  1903. to a common usb-storage quirk flag as follows:
  1904. a = SANE_SENSE (collect more than 18 bytes
  1905. of sense data);
  1906. c = FIX_CAPACITY (decrease the reported
  1907. device capacity by one sector);
  1908. h = CAPACITY_HEURISTICS (decrease the
  1909. reported device capacity by one
  1910. sector if the number is odd);
  1911. i = IGNORE_DEVICE (don't bind to this
  1912. device);
  1913. l = NOT_LOCKABLE (don't try to lock and
  1914. unlock ejectable media);
  1915. m = MAX_SECTORS_64 (don't transfer more
  1916. than 64 sectors = 32 KB at a time);
  1917. o = CAPACITY_OK (accept the capacity
  1918. reported by the device);
  1919. r = IGNORE_RESIDUE (the device reports
  1920. bogus residue values);
  1921. s = SINGLE_LUN (the device has only one
  1922. Logical Unit);
  1923. w = NO_WP_DETECT (don't test whether the
  1924. medium is write-protected).
  1925. Example: quirks=0419:aaf5:rl,0421:0433:rc
  1926. add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
  1927. kernel's map of available physical RAM.
  1928. vdso= [X86-32,SH,x86-64]
  1929. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  1930. vdso=1: enable VDSO (default)
  1931. vdso=0: disable VDSO mapping
  1932. vdso32= [X86-32,X86-64]
  1933. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  1934. vdso32=1: enable 32-bit VDSO (default)
  1935. vdso32=0: disable 32-bit VDSO mapping
  1936. vector= [IA-64,SMP]
  1937. vector=percpu: enable percpu vector domain
  1938. video= [FB] Frame buffer configuration
  1939. See Documentation/fb/modedb.txt.
  1940. vga= [BOOT,X86-32] Select a particular video mode
  1941. See Documentation/x86/boot.txt and
  1942. Documentation/svga.txt.
  1943. Use vga=ask for menu.
  1944. This is actually a boot loader parameter; the value is
  1945. passed to the kernel using a special protocol.
  1946. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1947. size of <nn>. This can be used to increase the
  1948. minimum size (128MB on x86). It can also be used to
  1949. decrease the size and leave more room for directly
  1950. mapped kernel RAM.
  1951. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1952. Format: <command>
  1953. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1954. Format: <command>
  1955. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1956. Format: <command>
  1957. waveartist= [HW,OSS]
  1958. Format: <io>,<irq>,<dma>,<dma2>
  1959. wd33c93= [HW,SCSI]
  1960. See header of drivers/scsi/wd33c93.c.
  1961. wd7000= [HW,SCSI]
  1962. See header of drivers/scsi/wd7000.c.
  1963. wdt= [WDT] Watchdog
  1964. See Documentation/watchdog/wdt.txt.
  1965. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1966. xd_geo= See header of drivers/block/xd.c.
  1967. xirc2ps_cs= [NET,PCMCIA]
  1968. Format:
  1969. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1970. norandmaps Don't use address space randomization. Equivalent to
  1971. echo 0 > /proc/sys/kernel/randomize_va_space
  1972. ______________________________________________________________________
  1973. TODO:
  1974. Add documentation for ALSA options.
  1975. Add more DRM drivers.