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