kernel-parameters.txt 93 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. Hyphens (dashes) and underscores are equivalent in parameter names, so
  15. log_buf_len=1M print-fatal-signals=1
  16. can also be entered as
  17. log-buf-len=1M print_fatal_signals=1
  18. This document may not be entirely up to date and comprehensive. The command
  19. "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
  20. module. Loadable modules, after being loaded into the running kernel, also
  21. reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
  22. parameters may be changed at runtime by the command
  23. "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
  24. The parameters listed below are only valid if certain kernel build options were
  25. enabled and if respective hardware is present. The text in square brackets at
  26. the beginning of each description states the restrictions within which a
  27. parameter is applicable:
  28. ACPI ACPI support is enabled.
  29. AGP AGP (Accelerated Graphics Port) is enabled.
  30. ALSA ALSA sound support is enabled.
  31. APIC APIC support is enabled.
  32. APM Advanced Power Management support is enabled.
  33. AVR32 AVR32 architecture is enabled.
  34. AX25 Appropriate AX.25 support is enabled.
  35. BLACKFIN Blackfin architecture is enabled.
  36. DRM Direct Rendering Management support is enabled.
  37. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
  38. EFI EFI Partitioning (GPT) is enabled
  39. EIDE EIDE/ATAPI support is enabled.
  40. FB The frame buffer device is enabled.
  41. GCOV GCOV profiling is enabled.
  42. HW Appropriate hardware is enabled.
  43. IA-64 IA-64 architecture is enabled.
  44. IMA Integrity measurement architecture is enabled.
  45. IOSCHED More than one I/O scheduler is enabled.
  46. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  47. IPV6 IPv6 support is enabled.
  48. ISAPNP ISA PnP code is enabled.
  49. ISDN Appropriate ISDN support is enabled.
  50. JOY Appropriate joystick support is enabled.
  51. KGDB Kernel debugger support is enabled.
  52. KVM Kernel Virtual Machine support is enabled.
  53. LIBATA Libata driver is enabled
  54. LP Printer support is enabled.
  55. LOOP Loopback device support is enabled.
  56. M68k M68k architecture is enabled.
  57. These options have more detailed description inside of
  58. Documentation/m68k/kernel-options.txt.
  59. MCA MCA bus support is enabled.
  60. MDA MDA console support is enabled.
  61. MOUSE Appropriate mouse support is enabled.
  62. MSI Message Signaled Interrupts (PCI).
  63. MTD MTD (Memory Technology Device) support is enabled.
  64. NET Appropriate network support is enabled.
  65. NUMA NUMA support is enabled.
  66. GENERIC_TIME The generic timeofday code is enabled.
  67. NFS Appropriate NFS support is enabled.
  68. OSS OSS sound support is enabled.
  69. PV_OPS A paravirtualized kernel is enabled.
  70. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  71. PARISC The PA-RISC architecture is enabled.
  72. PCI PCI bus support is enabled.
  73. PCIE PCI Express support is enabled.
  74. PCMCIA The PCMCIA subsystem is enabled.
  75. PNP Plug & Play support is enabled.
  76. PPC PowerPC architecture is enabled.
  77. PPT Parallel port support is enabled.
  78. PS2 Appropriate PS/2 support is enabled.
  79. RAM RAM disk support is enabled.
  80. S390 S390 architecture is enabled.
  81. SCSI Appropriate SCSI support is enabled.
  82. A lot of drivers has their options described inside of
  83. Documentation/scsi/.
  84. SECURITY Different security models are enabled.
  85. SELINUX SELinux support is enabled.
  86. SERIAL Serial support is enabled.
  87. SH SuperH architecture is enabled.
  88. SMP The kernel is an SMP kernel.
  89. SPARC Sparc architecture is enabled.
  90. SWSUSP Software suspend (hibernation) is enabled.
  91. SUSPEND System suspend states are enabled.
  92. FTRACE Function tracing enabled.
  93. TPM TPM drivers are enabled.
  94. TS Appropriate touchscreen support is enabled.
  95. UMS USB Mass Storage support is enabled.
  96. USB USB support is enabled.
  97. USBHID USB Human Interface Device support is enabled.
  98. V4L Video For Linux support is enabled.
  99. VGA The VGA console has been enabled.
  100. VT Virtual terminal support is enabled.
  101. WDT Watchdog support is enabled.
  102. XT IBM PC/XT MFM hard disk support is enabled.
  103. X86-32 X86-32, aka i386 architecture is enabled.
  104. X86-64 X86-64 architecture is enabled.
  105. More X86-64 boot options can be found in
  106. Documentation/x86/x86_64/boot-options.txt .
  107. X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
  108. In addition, the following text indicates that the option:
  109. BUGS= Relates to possible processor bugs on the said processor.
  110. KNL Is a kernel start-up parameter.
  111. BOOT Is a boot loader parameter.
  112. Parameters denoted with BOOT are actually interpreted by the boot
  113. loader, and have no meaning to the kernel directly.
  114. Do not modify the syntax of boot loader parameters without extreme
  115. need or coordination with <Documentation/x86/boot.txt>.
  116. There are also arch-specific kernel-parameters not documented here.
  117. See for example <Documentation/x86/x86_64/boot-options.txt>.
  118. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  119. a trailing = on the name of any parameter states that that parameter will
  120. be entered as an environment variable, whereas its absence indicates that
  121. it will appear as a kernel argument readable via /proc/cmdline by programs
  122. running once the system is up.
  123. The number of kernel parameters is not limited, but the length of the
  124. complete command line (parameters including spaces etc.) is limited to
  125. a fixed number of characters. This limit depends on the architecture
  126. and is between 256 and 4096 characters. It is defined in the file
  127. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  128. acpi= [HW,ACPI,X86]
  129. Advanced Configuration and Power Interface
  130. Format: { force | off | ht | strict | noirq | rsdt }
  131. force -- enable ACPI if default was off
  132. off -- disable ACPI if default was on
  133. noirq -- do not use ACPI for IRQ routing
  134. ht -- run only enough ACPI to enable Hyper Threading
  135. strict -- Be less tolerant of platforms that are not
  136. strictly ACPI specification compliant.
  137. rsdt -- prefer RSDT over (default) XSDT
  138. copy_dsdt -- copy DSDT to memory
  139. See also Documentation/power/pm.txt, pci=noacpi
  140. acpi_apic_instance= [ACPI, IOAPIC]
  141. Format: <int>
  142. 2: use 2nd APIC table, if available
  143. 1,0: use 1st APIC table
  144. default: 0
  145. acpi_backlight= [HW,ACPI]
  146. acpi_backlight=vendor
  147. acpi_backlight=video
  148. If set to vendor, prefer vendor specific driver
  149. (e.g. thinkpad_acpi, sony_acpi, etc.) instead
  150. of the ACPI video.ko driver.
  151. acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
  152. acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
  153. Format: <int>
  154. CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
  155. debug output. Bits in debug_layer correspond to a
  156. _COMPONENT in an ACPI source file, e.g.,
  157. #define _COMPONENT ACPI_PCI_COMPONENT
  158. Bits in debug_level correspond to a level in
  159. ACPI_DEBUG_PRINT statements, e.g.,
  160. ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
  161. The debug_level mask defaults to "info". See
  162. Documentation/acpi/debug.txt for more information about
  163. debug layers and levels.
  164. Enable processor driver info messages:
  165. acpi.debug_layer=0x20000000
  166. Enable PCI/PCI interrupt routing info messages:
  167. acpi.debug_layer=0x400000
  168. Enable AML "Debug" output, i.e., stores to the Debug
  169. object while interpreting AML:
  170. acpi.debug_layer=0xffffffff acpi.debug_level=0x2
  171. Enable all messages related to ACPI hardware:
  172. acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
  173. Some values produce so much output that the system is
  174. unusable. The "log_buf_len" parameter may be useful
  175. if you need to capture more output.
  176. acpi_display_output= [HW,ACPI]
  177. acpi_display_output=vendor
  178. acpi_display_output=video
  179. See above.
  180. acpi_irq_balance [HW,ACPI]
  181. ACPI will balance active IRQs
  182. default in APIC mode
  183. acpi_irq_nobalance [HW,ACPI]
  184. ACPI will not move active IRQs (default)
  185. default in PIC mode
  186. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  187. Format: <irq>,<irq>...
  188. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  189. use by PCI
  190. Format: <irq>,<irq>...
  191. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  192. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  193. Format: To spoof as Windows 98: ="Microsoft Windows"
  194. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  195. acpi_osi="string1" # add string1 -- only one string
  196. acpi_osi="!string2" # remove built-in string2
  197. acpi_osi= # disable all strings
  198. acpi_pm_good [X86]
  199. Override the pmtimer bug detection: force the kernel
  200. to assume that this machine's pmtimer latches its value
  201. and always returns good values.
  202. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  203. Format: { level | edge | high | low }
  204. acpi_serialize [HW,ACPI] force serialization of AML methods
  205. acpi_skip_timer_override [HW,ACPI]
  206. Recognize and ignore IRQ0/pin2 Interrupt Override.
  207. For broken nForce2 BIOS resulting in XT-PIC timer.
  208. acpi_sleep= [HW,ACPI] Sleep options
  209. Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
  210. old_ordering, s4_nonvs, sci_force_enable }
  211. See Documentation/power/video.txt for information on
  212. s3_bios and s3_mode.
  213. s3_beep is for debugging; it makes the PC's speaker beep
  214. as soon as the kernel's real-mode entry point is called.
  215. s4_nohwsig prevents ACPI hardware signature from being
  216. used during resume from hibernation.
  217. old_ordering causes the ACPI 1.0 ordering of the _PTS
  218. control method, with respect to putting devices into
  219. low power states, to be enforced (the ACPI 2.0 ordering
  220. of _PTS is used by default).
  221. s4_nonvs prevents the kernel from saving/restoring the
  222. ACPI NVS memory during hibernation.
  223. sci_force_enable causes the kernel to set SCI_EN directly
  224. on resume from S1/S3 (which is against the ACPI spec,
  225. but some broken systems don't work without it).
  226. acpi_use_timer_override [HW,ACPI]
  227. Use timer override. For some broken Nvidia NF5 boards
  228. that require a timer override, but don't have HPET
  229. acpi_enforce_resources= [ACPI]
  230. { strict | lax | no }
  231. Check for resource conflicts between native drivers
  232. and ACPI OperationRegions (SystemIO and SystemMemory
  233. only). IO ports and memory declared in ACPI might be
  234. used by the ACPI subsystem in arbitrary AML code and
  235. can interfere with legacy drivers.
  236. strict (default): access to resources claimed by ACPI
  237. is denied; legacy drivers trying to access reserved
  238. resources will fail to bind to device using them.
  239. lax: access to resources claimed by ACPI is allowed;
  240. legacy drivers trying to access reserved resources
  241. will bind successfully but a warning message is logged.
  242. no: ACPI OperationRegions are not marked as reserved,
  243. no further checks are performed.
  244. ad1848= [HW,OSS]
  245. Format: <io>,<irq>,<dma>,<dma2>,<type>
  246. add_efi_memmap [EFI; X86] Include EFI memory map in
  247. kernel's map of available physical RAM.
  248. advansys= [HW,SCSI]
  249. See header of drivers/scsi/advansys.c.
  250. aedsp16= [HW,OSS] Audio Excel DSP 16
  251. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  252. See also header of sound/oss/aedsp16.c.
  253. agp= [AGP]
  254. { off | try_unsupported }
  255. off: disable AGP support
  256. try_unsupported: try to drive unsupported chipsets
  257. (may crash computer or cause data corruption)
  258. aha152x= [HW,SCSI]
  259. See Documentation/scsi/aha152x.txt.
  260. aha1542= [HW,SCSI]
  261. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  262. aic7xxx= [HW,SCSI]
  263. See Documentation/scsi/aic7xxx.txt.
  264. aic79xx= [HW,SCSI]
  265. See Documentation/scsi/aic79xx.txt.
  266. alignment= [KNL,ARM]
  267. Allow the default userspace alignment fault handler
  268. behaviour to be specified. Bit 0 enables warnings,
  269. bit 1 enables fixups, and bit 2 sends a segfault.
  270. amd_iommu= [HW,X86-84]
  271. Pass parameters to the AMD IOMMU driver in the system.
  272. Possible values are:
  273. fullflush - enable flushing of IO/TLB entries when
  274. they are unmapped. Otherwise they are
  275. flushed before they will be reused, which
  276. is a lot of faster
  277. off - do not initialize any AMD IOMMU found in
  278. the system
  279. amijoy.map= [HW,JOY] Amiga joystick support
  280. Map of devices attached to JOY0DAT and JOY1DAT
  281. Format: <a>,<b>
  282. See also Documentation/kernel/input/joystick.txt
  283. analog.map= [HW,JOY] Analog joystick and gamepad support
  284. Specifies type or capabilities of an analog joystick
  285. connected to one of 16 gameports
  286. Format: <type1>,<type2>,..<type16>
  287. apc= [HW,SPARC]
  288. Power management functions (SPARCstation-4/5 + deriv.)
  289. Format: noidle
  290. Disable APC CPU standby support. SPARCstation-Fox does
  291. not play well with APC CPU idle - disable it if you have
  292. APC and your system crashes randomly.
  293. apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
  294. Change the output verbosity whilst booting
  295. Format: { quiet (default) | verbose | debug }
  296. Change the amount of debugging information output
  297. when initialising the APIC and IO-APIC components.
  298. autoconf= [IPV6]
  299. See Documentation/networking/ipv6.txt.
  300. show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
  301. Limit apic dumping. The parameter defines the maximal
  302. number of local apics being dumped. Also it is possible
  303. to set it to "all" by meaning -- no limit here.
  304. Format: { 1 (default) | 2 | ... | all }.
  305. The parameter valid if only apic=debug or
  306. apic=verbose is specified.
  307. Example: apic=debug show_lapic=all
  308. apm= [APM] Advanced Power Management
  309. See header of arch/x86/kernel/apm_32.c.
  310. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  311. Format: <io>,<irq>,<nodeID>
  312. ataflop= [HW,M68k]
  313. atarimouse= [HW,MOUSE] Atari Mouse
  314. atascsi= [HW,SCSI] Atari SCSI
  315. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  316. EzKey and similar keyboards
  317. atkbd.reset= [HW] Reset keyboard during initialization
  318. atkbd.set= [HW] Select keyboard code set
  319. Format: <int> (2 = AT (default), 3 = PS/2)
  320. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  321. keyboards
  322. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  323. Format: <bool> (0 = real, 1 = synthetic (default))
  324. atkbd.softrepeat= [HW]
  325. Use software keyboard repeat
  326. autotest [IA64]
  327. baycom_epp= [HW,AX25]
  328. Format: <io>,<mode>
  329. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  330. Format: <io>,<mode>
  331. See header of drivers/net/hamradio/baycom_par.c.
  332. baycom_ser_fdx= [HW,AX25]
  333. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  334. Format: <io>,<irq>,<mode>[,<baud>]
  335. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  336. baycom_ser_hdx= [HW,AX25]
  337. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  338. Format: <io>,<irq>,<mode>
  339. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  340. boot_delay= Milliseconds to delay each printk during boot.
  341. Values larger than 10 seconds (10000) are changed to
  342. no delay (0).
  343. Format: integer
  344. bootmem_debug [KNL] Enable bootmem allocator debug messages.
  345. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  346. bttv.radio= Most important insmod options are available as
  347. kernel args too.
  348. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  349. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  350. BusLogic= [HW,SCSI]
  351. See drivers/scsi/BusLogic.c, comment before function
  352. BusLogic_ParseDriverOptions().
  353. c101= [NET] Moxa C101 synchronous serial card
  354. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  355. Sometimes CPU hardware bugs make them report the cache
  356. size incorrectly. The kernel will attempt work arounds
  357. to fix known problems, but for some CPUs it is not
  358. possible to determine what the correct size should be.
  359. This option provides an override for these situations.
  360. capability.disable=
  361. [SECURITY] Disable capabilities. This would normally
  362. be used only if an alternative security model is to be
  363. configured. Potentially dangerous and should only be
  364. used if you are entirely sure of the consequences.
  365. ccw_timeout_log [S390]
  366. See Documentation/s390/CommonIO for details.
  367. cgroup_disable= [KNL] Disable a particular controller
  368. Format: {name of the controller(s) to disable}
  369. {Currently supported controllers - "memory"}
  370. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  371. Format: { "0" | "1" }
  372. See security/selinux/Kconfig help text.
  373. 0 -- check protection applied by kernel (includes
  374. any implied execute protection).
  375. 1 -- check protection requested by application.
  376. Default value is set via a kernel config option.
  377. Value can be changed at runtime via
  378. /selinux/checkreqprot.
  379. cio_ignore= [S390]
  380. See Documentation/s390/CommonIO for details.
  381. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  382. [Deprecated]
  383. Forces specified clocksource (if available) to be used
  384. when calculating gettimeofday(). If specified
  385. clocksource is not available, it defaults to PIT.
  386. Format: { pit | tsc | cyclone | pmtmr }
  387. clocksource= [GENERIC_TIME] Override the default clocksource
  388. Format: <string>
  389. Override the default clocksource and use the clocksource
  390. with the name specified.
  391. Some clocksource names to choose from, depending on
  392. the platform:
  393. [all] jiffies (this is the base, fallback clocksource)
  394. [ACPI] acpi_pm
  395. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  396. pxa_timer,timer3,32k_counter,timer0_1
  397. [AVR32] avr32
  398. [X86-32] pit,hpet,tsc,vmi-timer;
  399. scx200_hrt on Geode; cyclone on IBM x440
  400. [MIPS] MIPS
  401. [PARISC] cr16
  402. [S390] tod
  403. [SH] SuperH
  404. [SPARC64] tick
  405. [X86-64] hpet,tsc
  406. clearcpuid=BITNUM [X86]
  407. Disable CPUID feature X for the kernel. See
  408. arch/x86/include/asm/cpufeature.h for the valid bit
  409. numbers. Note the Linux specific bits are not necessarily
  410. stable over kernel options, but the vendor specific
  411. ones should be.
  412. Also note that user programs calling CPUID directly
  413. or using the feature without checking anything
  414. will still see it. This just prevents it from
  415. being used by the kernel or shown in /proc/cpuinfo.
  416. Also note the kernel might malfunction if you disable
  417. some critical bits.
  418. cmo_free_hint= [PPC] Format: { yes | no }
  419. Specify whether pages are marked as being inactive
  420. when they are freed. This is used in CMO environments
  421. to determine OS memory pressure for page stealing by
  422. a hypervisor.
  423. Default: yes
  424. code_bytes [X86] How many bytes of object code to print
  425. in an oops report.
  426. Range: 0 - 8192
  427. Default: 64
  428. com20020= [HW,NET] ARCnet - COM20020 chipset
  429. Format:
  430. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  431. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  432. Format: <io>[,<irq>]
  433. com90xx= [HW,NET]
  434. ARCnet - COM90xx chipset (memory-mapped buffers)
  435. Format: <io>[,<irq>[,<memstart>]]
  436. condev= [HW,S390] console device
  437. conmode=
  438. console= [KNL] Output console device and options.
  439. tty<n> Use the virtual console device <n>.
  440. ttyS<n>[,options]
  441. ttyUSB0[,options]
  442. Use the specified serial port. The options are of
  443. the form "bbbbpnf", where "bbbb" is the baud rate,
  444. "p" is parity ("n", "o", or "e"), "n" is number of
  445. bits, and "f" is flow control ("r" for RTS or
  446. omit it). Default is "9600n8".
  447. See Documentation/serial-console.txt for more
  448. information. See
  449. Documentation/networking/netconsole.txt for an
  450. alternative.
  451. uart[8250],io,<addr>[,options]
  452. uart[8250],mmio,<addr>[,options]
  453. Start an early, polled-mode console on the 8250/16550
  454. UART at the specified I/O port or MMIO address,
  455. switching to the matching ttyS device later. The
  456. options are the same as for ttyS, above.
  457. If the device connected to the port is not a TTY but a braille
  458. device, prepend "brl," before the device type, for instance
  459. console=brl,ttyS0
  460. For now, only VisioBraille is supported.
  461. consoleblank= [KNL] The console blank (screen saver) timeout in
  462. seconds. Defaults to 10*60 = 10mins. A value of 0
  463. disables the blank timer.
  464. coredump_filter=
  465. [KNL] Change the default value for
  466. /proc/<pid>/coredump_filter.
  467. See also Documentation/filesystems/proc.txt.
  468. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  469. Format:
  470. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  471. crashkernel=nn[KMG]@ss[KMG]
  472. [KNL] Reserve a chunk of physical memory to
  473. hold a kernel to switch to with kexec on panic.
  474. crashkernel=range1:size1[,range2:size2,...][@offset]
  475. [KNL] Same as above, but depends on the memory
  476. in the running system. The syntax of range is
  477. start-[end] where start and end are both
  478. a memory unit (amount[KMG]). See also
  479. Documentation/kdump/kdump.txt for a example.
  480. cs89x0_dma= [HW,NET]
  481. Format: <dma>
  482. cs89x0_media= [HW,NET]
  483. Format: { rj45 | aui | bnc }
  484. dasd= [HW,NET]
  485. See header of drivers/s390/block/dasd_devmap.c.
  486. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  487. (one device per port)
  488. Format: <port#>,<type>
  489. See also Documentation/input/joystick-parport.txt
  490. debug [KNL] Enable kernel debugging (events log level).
  491. debug_locks_verbose=
  492. [KNL] verbose self-tests
  493. Format=<0|1>
  494. Print debugging info while doing the locking API
  495. self-tests.
  496. We default to 0 (no extra messages), setting it to
  497. 1 will print _a lot_ more information - normally
  498. only useful to kernel developers.
  499. debug_objects [KNL] Enable object debugging
  500. no_debug_objects
  501. [KNL] Disable object debugging
  502. debugpat [X86] Enable PAT debugging
  503. decnet.addr= [HW,NET]
  504. Format: <area>[,<node>]
  505. See also Documentation/networking/decnet.txt.
  506. default_hugepagesz=
  507. [same as hugepagesz=] The size of the default
  508. HugeTLB page size. This is the size represented by
  509. the legacy /proc/ hugepages APIs, used for SHM, and
  510. default size when mounting hugetlbfs filesystems.
  511. Defaults to the default architecture's huge page size
  512. if not specified.
  513. dhash_entries= [KNL]
  514. Set number of hash buckets for dentry cache.
  515. digi= [HW,SERIAL]
  516. IO parameters + enable/disable command.
  517. digiepca= [HW,SERIAL]
  518. See drivers/char/README.epca and
  519. Documentation/serial/digiepca.txt.
  520. disable= [IPV6]
  521. See Documentation/networking/ipv6.txt.
  522. disable_ipv6= [IPV6]
  523. See Documentation/networking/ipv6.txt.
  524. disable_mtrr_cleanup [X86]
  525. The kernel tries to adjust MTRR layout from continuous
  526. to discrete, to make X server driver able to add WB
  527. entry later. This parameter disables that.
  528. disable_mtrr_trim [X86, Intel and AMD only]
  529. By default the kernel will trim any uncacheable
  530. memory out of your available memory pool based on
  531. MTRR settings. This parameter disables that behavior,
  532. possibly causing your machine to run very slowly.
  533. disable_timer_pin_1 [X86]
  534. Disable PIN 1 of APIC timer
  535. Can be useful to work around chipset bugs.
  536. dmasound= [HW,OSS] Sound subsystem buffers
  537. dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
  538. this option disables the debugging code at boot.
  539. dma_debug_entries=<number>
  540. This option allows to tune the number of preallocated
  541. entries for DMA-API debugging code. One entry is
  542. required per DMA-API allocation. Use this if the
  543. DMA-API debugging code disables itself because the
  544. architectural default is too low.
  545. dma_debug_driver=<driver_name>
  546. With this option the DMA-API debugging driver
  547. filter feature can be enabled at boot time. Just
  548. pass the driver to filter for as the parameter.
  549. The filter can be disabled or changed to another
  550. driver later using sysfs.
  551. dscc4.setup= [NET]
  552. dtc3181e= [HW,SCSI]
  553. dynamic_printk Enables pr_debug()/dev_dbg() calls if
  554. CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
  555. These can also be switched on/off via
  556. <debugfs>/dynamic_printk/modules
  557. earlycon= [KNL] Output early console device and options.
  558. uart[8250],io,<addr>[,options]
  559. uart[8250],mmio,<addr>[,options]
  560. Start an early, polled-mode console on the 8250/16550
  561. UART at the specified I/O port or MMIO address.
  562. The options are the same as for ttyS, above.
  563. earlyprintk= [X86,SH,BLACKFIN]
  564. earlyprintk=vga
  565. earlyprintk=serial[,ttySn[,baudrate]]
  566. earlyprintk=ttySn[,baudrate]
  567. earlyprintk=dbgp[debugController#]
  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. ekgdboc= [X86,KGDB] Allow early kernel console debugging
  577. ekgdboc=kbd
  578. This is desgined to be used in conjunction with
  579. the boot argument: earlyprintk=vga
  580. eata= [HW,SCSI]
  581. edd= [EDD]
  582. Format: {"off" | "on" | "skip[mbr]"}
  583. eisa_irq_edge= [PARISC,HW]
  584. See header of drivers/parisc/eisa.c.
  585. elanfreq= [X86-32]
  586. See comment before function elanfreq_setup() in
  587. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
  588. elevator= [IOSCHED]
  589. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  590. See Documentation/block/as-iosched.txt and
  591. Documentation/block/deadline-iosched.txt for details.
  592. elfcorehdr= [IA64,PPC,SH,X86]
  593. Specifies physical address of start of kernel core
  594. image elf header. Generally kexec loader will
  595. pass this option to capture kernel.
  596. See Documentation/kdump/kdump.txt for details.
  597. enable_mtrr_cleanup [X86]
  598. The kernel tries to adjust MTRR layout from continuous
  599. to discrete, to make X server driver able to add WB
  600. entry later. This parameter enables that.
  601. enable_timer_pin_1 [X86]
  602. Enable PIN 1 of APIC timer
  603. Can be useful to work around chipset bugs
  604. (in particular on some ATI chipsets).
  605. The kernel tries to set a reasonable default.
  606. enforcing [SELINUX] Set initial enforcing status.
  607. Format: {"0" | "1"}
  608. See security/selinux/Kconfig help text.
  609. 0 -- permissive (log only, no denials).
  610. 1 -- enforcing (deny and log).
  611. Default value is 0.
  612. Value can be changed at runtime via /selinux/enforce.
  613. ether= [HW,NET] Ethernet cards parameters
  614. This option is obsoleted by the "netdev=" option, which
  615. has equivalent usage. See its documentation for details.
  616. failslab=
  617. fail_page_alloc=
  618. fail_make_request=[KNL]
  619. General fault injection mechanism.
  620. Format: <interval>,<probability>,<space>,<times>
  621. See also /Documentation/fault-injection/.
  622. fd_mcs= [HW,SCSI]
  623. See header of drivers/scsi/fd_mcs.c.
  624. fdomain= [HW,SCSI]
  625. See header of drivers/scsi/fdomain.c.
  626. floppy= [HW]
  627. See Documentation/blockdev/floppy.txt.
  628. force_pal_cache_flush
  629. [IA-64] Avoid check_sal_cache_flush which may hang on
  630. buggy SAL_CACHE_FLUSH implementations. Using this
  631. parameter will force ia64_sal_cache_flush to call
  632. ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
  633. ftrace=[tracer]
  634. [FTRACE] will set and start the specified tracer
  635. as early as possible in order to facilitate early
  636. boot debugging.
  637. ftrace_dump_on_oops[=orig_cpu]
  638. [FTRACE] will dump the trace buffers on oops.
  639. If no parameter is passed, ftrace will dump
  640. buffers of all CPUs, but if you pass orig_cpu, it will
  641. dump only the buffer of the CPU that triggered the
  642. oops.
  643. ftrace_filter=[function-list]
  644. [FTRACE] Limit the functions traced by the function
  645. tracer at boot up. function-list is a comma separated
  646. list of functions. This list can be changed at run
  647. time by the set_ftrace_filter file in the debugfs
  648. tracing directory.
  649. ftrace_notrace=[function-list]
  650. [FTRACE] Do not trace the functions specified in
  651. function-list. This list can be changed at run time
  652. by the set_ftrace_notrace file in the debugfs
  653. tracing directory.
  654. ftrace_graph_filter=[function-list]
  655. [FTRACE] Limit the top level callers functions traced
  656. by the function graph tracer at boot up.
  657. function-list is a comma separated list of functions
  658. that can be changed at run time by the
  659. set_graph_function file in the debugfs tracing directory.
  660. gamecon.map[2|3]=
  661. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  662. support via parallel port (up to 5 devices per port)
  663. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  664. See also Documentation/input/joystick-parport.txt
  665. gamma= [HW,DRM]
  666. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  667. Format: off | on
  668. default: on
  669. gcov_persist= [GCOV] When non-zero (default), profiling data for
  670. kernel modules is saved and remains accessible via
  671. debugfs, even when the module is unloaded/reloaded.
  672. When zero, profiling data is discarded and associated
  673. debugfs files are removed at module unload time.
  674. gdth= [HW,SCSI]
  675. See header of drivers/scsi/gdth.c.
  676. gpt [EFI] Forces disk with valid GPT signature but
  677. invalid Protective MBR to be treated as GPT.
  678. gvp11= [HW,SCSI]
  679. hashdist= [KNL,NUMA] Large hashes allocated during boot
  680. are distributed across NUMA nodes. Defaults on
  681. for 64bit NUMA, off otherwise.
  682. Format: 0 | 1 (for off | on)
  683. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  684. hd= [EIDE] (E)IDE hard drive subsystem geometry
  685. Format: <cyl>,<head>,<sect>
  686. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  687. size of <nn>. This works even on boxes that have no
  688. highmem otherwise. This also works to reduce highmem
  689. size on bigger boxes.
  690. highres= [KNL] Enable/disable high resolution timer mode.
  691. Valid parameters: "on", "off"
  692. Default: "on"
  693. hisax= [HW,ISDN]
  694. See Documentation/isdn/README.HiSax.
  695. hlt [BUGS=ARM,SH]
  696. hpet= [X86-32,HPET] option to control HPET usage
  697. Format: { enable (default) | disable | force |
  698. verbose }
  699. disable: disable HPET and use PIT instead
  700. force: allow force enabled of undocumented chips (ICH4,
  701. VIA, nVidia)
  702. verbose: show contents of HPET registers during setup
  703. hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
  704. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
  705. On x86-64 and powerpc, this option can be specified
  706. multiple times interleaved with hugepages= to reserve
  707. huge pages of different sizes. Valid pages sizes on
  708. x86-64 are 2M (when the CPU supports "pse") and 1G
  709. (when the CPU supports the "pdpe1gb" cpuinfo flag)
  710. Note that 1GB pages can only be allocated at boot time
  711. using hugepages= and not freed afterwards.
  712. hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
  713. terminal devices. Valid values: 0..8
  714. hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
  715. If specified, z/VM IUCV HVC accepts connections
  716. from listed z/VM user IDs only.
  717. i2c_bus= [HW] Override the default board specific I2C bus speed
  718. or register an additional I2C bus that is not
  719. registered from board initialization code.
  720. Format:
  721. <bus_id>,<clkrate>
  722. i8042.debug [HW] Toggle i8042 debug mode
  723. i8042.direct [HW] Put keyboard port into non-translated mode
  724. i8042.dumbkbd [HW] Pretend that controller can only read data from
  725. keyboard and cannot control its state
  726. (Don't attempt to blink the leds)
  727. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  728. i8042.nokbd [HW] Don't check/create keyboard port
  729. i8042.noloop [HW] Disable the AUX Loopback command while probing
  730. for the AUX port
  731. i8042.nomux [HW] Don't check presence of an active multiplexing
  732. controller
  733. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  734. controllers
  735. i8042.panicblink=
  736. [HW] Frequency with which keyboard LEDs should blink
  737. when kernel panics (default is 0.5 sec)
  738. i8042.reset [HW] Reset the controller during init and cleanup
  739. i8042.unlock [HW] Unlock (ignore) the keylock
  740. i810= [HW,DRM]
  741. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  742. indicates that the driver is running on unsupported
  743. hardware.
  744. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  745. does not match list of supported models.
  746. i8k.power_status
  747. [HW] Report power status in /proc/i8k
  748. (disabled by default)
  749. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  750. capability is set.
  751. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  752. See Documentation/mca.txt.
  753. icn= [HW,ISDN]
  754. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  755. ide-core.nodma= [HW] (E)IDE subsystem
  756. Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
  757. .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
  758. .cdrom .chs .ignore_cable are additional options
  759. See Documentation/ide/ide.txt.
  760. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  761. Claim all unknown PCI IDE storage controllers.
  762. idle= [X86]
  763. Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
  764. Poll forces a polling idle loop that can slightly
  765. improve the performance of waking up a idle CPU, but
  766. will use a lot of power and make the system run hot.
  767. Not recommended.
  768. idle=mwait: On systems which support MONITOR/MWAIT but
  769. the kernel chose to not use it because it doesn't save
  770. as much power as a normal idle loop, use the
  771. MONITOR/MWAIT idle loop anyways. Performance should be
  772. the same as idle=poll.
  773. idle=halt: Halt is forced to be used for CPU idle.
  774. In such case C2/C3 won't be used again.
  775. idle=nomwait: Disable mwait for CPU C-states
  776. ignore_loglevel [KNL]
  777. Ignore loglevel setting - this will print /all/
  778. kernel messages to the console. Useful for debugging.
  779. ihash_entries= [KNL]
  780. Set number of hash buckets for inode cache.
  781. ima_audit= [IMA]
  782. Format: { "0" | "1" }
  783. 0 -- integrity auditing messages. (Default)
  784. 1 -- enable informational integrity auditing messages.
  785. ima_hash= [IMA]
  786. Format: { "sha1" | "md5" }
  787. default: "sha1"
  788. ima_tcb [IMA]
  789. Load a policy which meets the needs of the Trusted
  790. Computing Base. This means IMA will measure all
  791. programs exec'd, files mmap'd for exec, and all files
  792. opened for read by uid=0.
  793. in2000= [HW,SCSI]
  794. See header of drivers/scsi/in2000.c.
  795. init= [KNL]
  796. Format: <full_path>
  797. Run specified binary instead of /sbin/init as init
  798. process.
  799. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  800. for working out where the kernel is dying during
  801. startup.
  802. initrd= [BOOT] Specify the location of the initial ramdisk
  803. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  804. Format: <irq>
  805. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  806. on
  807. Enable intel iommu driver.
  808. off
  809. Disable intel iommu driver.
  810. igfx_off [Default Off]
  811. By default, gfx is mapped as normal device. If a gfx
  812. device has a dedicated DMAR unit, the DMAR unit is
  813. bypassed by not enabling DMAR with this option. In
  814. this case, gfx device will use physical address for
  815. DMA.
  816. forcedac [x86_64]
  817. With this option iommu will not optimize to look
  818. for io virtual address below 32 bit forcing dual
  819. address cycle on pci bus for cards supporting greater
  820. than 32 bit addressing. The default is to look
  821. for translation below 32 bit and if not available
  822. then look in the higher range.
  823. strict [Default Off]
  824. With this option on every unmap_single operation will
  825. result in a hardware IOTLB flush operation as opposed
  826. to batching them for performance.
  827. inttest= [IA64]
  828. iomem= Disable strict checking of access to MMIO memory
  829. strict regions from userspace.
  830. relaxed
  831. iommu= [x86]
  832. off
  833. force
  834. noforce
  835. biomerge
  836. panic
  837. nopanic
  838. merge
  839. nomerge
  840. forcesac
  841. soft
  842. pt [x86, IA64]
  843. io7= [HW] IO7 for Marvel based alpha systems
  844. See comment before marvel_specify_io7 in
  845. arch/alpha/kernel/core_marvel.c.
  846. io_delay= [X86] I/O delay method
  847. 0x80
  848. Standard port 0x80 based delay
  849. 0xed
  850. Alternate port 0xed based delay (needed on some systems)
  851. udelay
  852. Simple two microseconds delay
  853. none
  854. No delay
  855. ip= [IP_PNP]
  856. See Documentation/filesystems/nfs/nfsroot.txt.
  857. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  858. See comment before ip2_setup() in
  859. drivers/char/ip2/ip2base.c.
  860. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  861. See header of drivers/scsi/ips.c.
  862. irqfixup [HW]
  863. When an interrupt is not handled search all handlers
  864. for it. Intended to get systems with badly broken
  865. firmware running.
  866. irqpoll [HW]
  867. When an interrupt is not handled search all handlers
  868. for it. Also check all handlers each timer
  869. interrupt. Intended to get systems with badly broken
  870. firmware running.
  871. isapnp= [ISAPNP]
  872. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  873. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  874. Format:
  875. <cpu number>,...,<cpu number>
  876. or
  877. <cpu number>-<cpu number>
  878. (must be a positive range in ascending order)
  879. or a mixture
  880. <cpu number>,...,<cpu number>-<cpu number>
  881. This option can be used to specify one or more CPUs
  882. to isolate from the general SMP balancing and scheduling
  883. algorithms. You can move a process onto or off an
  884. "isolated" CPU via the CPU affinity syscalls or cpuset.
  885. <cpu number> begins at 0 and the maximum value is
  886. "number of CPUs in system - 1".
  887. This option is the preferred way to isolate CPUs. The
  888. alternative -- manually setting the CPU mask of all
  889. tasks in the system -- can cause problems and
  890. suboptimal load balancer performance.
  891. iucv= [HW,NET]
  892. js= [HW,JOY] Analog joystick
  893. See Documentation/input/joystick.txt.
  894. keepinitrd [HW,ARM]
  895. kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  896. specifies the amount of memory usable by the kernel
  897. for non-movable allocations. The requested amount is
  898. spread evenly throughout all nodes in the system. The
  899. remaining memory in each node is used for Movable
  900. pages. In the event, a node is too small to have both
  901. kernelcore and Movable pages, kernelcore pages will
  902. take priority and other nodes will have a larger number
  903. of kernelcore pages. The Movable zone is used for the
  904. allocation of pages that may be reclaimed or moved
  905. by the page migration subsystem. This means that
  906. HugeTLB pages may not be allocated from this zone.
  907. Note that allocations like PTEs-from-HighMem still
  908. use the HighMem zone if it exists, and the Normal
  909. zone if it does not.
  910. kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
  911. Format: <Controller#>[,poll interval]
  912. The controller # is the number of the ehci usb debug
  913. port as it is probed via PCI. The poll interval is
  914. optional and is the number seconds in between
  915. each poll cycle to the debug port in case you need
  916. the functionality for interrupting the kernel with
  917. gdb or control-c on the dbgp connection. When
  918. not using this parameter you use sysrq-g to break into
  919. the kernel debugger.
  920. kgdboc= [KGDB,HW] kgdb over consoles.
  921. Requires a tty driver that supports console polling,
  922. or a supported polling keyboard driver (non-usb).
  923. Serial only format: <serial_device>[,baud]
  924. keyboard only format: kbd
  925. keyboard and serial format: kbd,<serial_device>[,baud]
  926. kgdbwait [KGDB] Stop kernel execution and enter the
  927. kernel debugger at the earliest opportunity.
  928. kmac= [MIPS] korina ethernet MAC address.
  929. Configure the RouterBoard 532 series on-chip
  930. Ethernet adapter MAC address.
  931. kmemleak= [KNL] Boot-time kmemleak enable/disable
  932. Valid arguments: on, off
  933. Default: on
  934. kstack=N [X86] Print N words from the kernel stack
  935. in oops dumps.
  936. kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
  937. Default is 0 (don't ignore, but inject #GP)
  938. kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
  939. Default is 1 (enabled)
  940. kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
  941. Default is 0 (off)
  942. kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
  943. for all guests.
  944. Default is 1 (enabled) if in 64bit or 32bit-PAE mode
  945. kvm-intel.bypass_guest_pf=
  946. [KVM,Intel] Disables bypassing of guest page faults
  947. on Intel chips. Default is 1 (enabled)
  948. kvm-intel.ept= [KVM,Intel] Disable extended page tables
  949. (virtualized MMU) support on capable Intel chips.
  950. Default is 1 (enabled)
  951. kvm-intel.emulate_invalid_guest_state=
  952. [KVM,Intel] Enable emulation of invalid guest states
  953. Default is 0 (disabled)
  954. kvm-intel.flexpriority=
  955. [KVM,Intel] Disable FlexPriority feature (TPR shadow).
  956. Default is 1 (enabled)
  957. kvm-intel.unrestricted_guest=
  958. [KVM,Intel] Disable unrestricted guest feature
  959. (virtualized real and unpaged mode) on capable
  960. Intel chips. Default is 1 (enabled)
  961. kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
  962. feature (tagged TLBs) on capable Intel chips.
  963. Default is 1 (enabled)
  964. l2cr= [PPC]
  965. l3cr= [PPC]
  966. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  967. disabled it.
  968. lapic_timer_c2_ok [X86,APIC] trust the local apic timer
  969. in C2 power state.
  970. libata.dma= [LIBATA] DMA control
  971. libata.dma=0 Disable all PATA and SATA DMA
  972. libata.dma=1 PATA and SATA Disk DMA only
  973. libata.dma=2 ATAPI (CDROM) DMA only
  974. libata.dma=4 Compact Flash DMA only
  975. Combinations also work, so libata.dma=3 enables DMA
  976. for disks and CDROMs, but not CFs.
  977. libata.ignore_hpa= [LIBATA] Ignore HPA limit
  978. libata.ignore_hpa=0 keep BIOS limits (default)
  979. libata.ignore_hpa=1 ignore limits, using full disk
  980. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  981. when set.
  982. Format: <int>
  983. libata.force= [LIBATA] Force configurations. The format is comma
  984. separated list of "[ID:]VAL" where ID is
  985. PORT[.DEVICE]. PORT and DEVICE are decimal numbers
  986. matching port, link or device. Basically, it matches
  987. the ATA ID string printed on console by libata. If
  988. the whole ID part is omitted, the last PORT and DEVICE
  989. values are used. If ID hasn't been specified yet, the
  990. configuration applies to all ports, links and devices.
  991. If only DEVICE is omitted, the parameter applies to
  992. the port and all links and devices behind it. DEVICE
  993. number of 0 either selects the first device or the
  994. first fan-out link behind PMP device. It does not
  995. select the host link. DEVICE number of 15 selects the
  996. host link and device attached to it.
  997. The VAL specifies the configuration to force. As long
  998. as there's no ambiguity shortcut notation is allowed.
  999. For example, both 1.5 and 1.5G would work for 1.5Gbps.
  1000. The following configurations can be forced.
  1001. * Cable type: 40c, 80c, short40c, unk, ign or sata.
  1002. Any ID with matching PORT is used.
  1003. * SATA link speed limit: 1.5Gbps or 3.0Gbps.
  1004. * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
  1005. udma[/][16,25,33,44,66,100,133] notation is also
  1006. allowed.
  1007. * [no]ncq: Turn on or off NCQ.
  1008. * nohrst, nosrst, norst: suppress hard, soft
  1009. and both resets.
  1010. If there are multiple matching configurations changing
  1011. the same attribute, the last one is used.
  1012. lmb=debug [KNL] Enable lmb debug messages.
  1013. load_ramdisk= [RAM] List of ramdisks to load from floppy
  1014. See Documentation/blockdev/ramdisk.txt.
  1015. lockd.nlm_grace_period=P [NFS] Assign grace period.
  1016. Format: <integer>
  1017. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  1018. Format: <integer>
  1019. lockd.nlm_timeout=T [NFS] Assign timeout value.
  1020. Format: <integer>
  1021. lockd.nlm_udpport=M [NFS] Assign UDP port.
  1022. Format: <integer>
  1023. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  1024. Format: <irq>
  1025. loglevel= All Kernel Messages with a loglevel smaller than the
  1026. console loglevel will be printed to the console. It can
  1027. also be changed with klogd or other programs. The
  1028. loglevels are defined as follows:
  1029. 0 (KERN_EMERG) system is unusable
  1030. 1 (KERN_ALERT) action must be taken immediately
  1031. 2 (KERN_CRIT) critical conditions
  1032. 3 (KERN_ERR) error conditions
  1033. 4 (KERN_WARNING) warning conditions
  1034. 5 (KERN_NOTICE) normal but significant condition
  1035. 6 (KERN_INFO) informational
  1036. 7 (KERN_DEBUG) debug-level messages
  1037. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  1038. Format: { n | nk | nM }
  1039. n must be a power of two. The default size
  1040. is set in the kernel config file.
  1041. logo.nologo [FB] Disables display of the built-in Linux logo.
  1042. This may be used to provide more screen space for
  1043. kernel log messages and is useful when debugging
  1044. kernel boot problems.
  1045. lp=0 [LP] Specify parallel ports to use, e.g,
  1046. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  1047. lp=reset first parallel port). 'lp=0' disables the
  1048. lp=auto printer driver. 'lp=reset' (which can be
  1049. specified in addition to the ports) causes
  1050. attached printers to be reset. Using
  1051. lp=port1,port2,... specifies the parallel ports
  1052. to associate lp devices with, starting with
  1053. lp0. A port specification may be 'none' to skip
  1054. that lp device, or a parport name such as
  1055. 'parport0'. Specifying 'lp=auto' instead of a
  1056. port specification list means that device IDs
  1057. from each port should be examined, to see if
  1058. an IEEE 1284-compliant printer is attached; if
  1059. so, the driver will manage that printer.
  1060. See also header of drivers/char/lp.c.
  1061. lpj=n [KNL]
  1062. Sets loops_per_jiffy to given constant, thus avoiding
  1063. time-consuming boot-time autodetection (up to 250 ms per
  1064. CPU). 0 enables autodetection (default). To determine
  1065. the correct value for your kernel, boot with normal
  1066. autodetection and see what value is printed. Note that
  1067. on SMP systems the preset will be applied to all CPUs,
  1068. which is likely to cause problems if your CPUs need
  1069. significantly divergent settings. An incorrect value
  1070. will cause delays in the kernel to be wrong, leading to
  1071. unpredictable I/O errors and other breakage. Although
  1072. unlikely, in the extreme case this might damage your
  1073. hardware.
  1074. ltpc= [NET]
  1075. Format: <io>,<irq>,<dma>
  1076. mac5380= [HW,SCSI] Format:
  1077. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  1078. machvec= [IA64] Force the use of a particular machine-vector
  1079. (machvec) in a generic kernel.
  1080. Example: machvec=hpzx1_swiotlb
  1081. machtype= [Loongson] Share the same kernel image file between different
  1082. yeeloong laptop.
  1083. Example: machtype=lemote-yeeloong-2f-7inch
  1084. max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
  1085. than or equal to this physical address is ignored.
  1086. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  1087. should make use of. maxcpus=n : n >= 0 limits the
  1088. kernel to using 'n' processors. n=0 is a special case,
  1089. it is equivalent to "nosmp", which also disables
  1090. the IO APIC.
  1091. max_loop= [LOOP] Maximum number of loopback devices that can
  1092. be mounted
  1093. Format: <1-256>
  1094. max_luns= [SCSI] Maximum number of LUNs to probe.
  1095. Should be between 1 and 2^32-1.
  1096. max_report_luns=
  1097. [SCSI] Maximum number of LUNs received.
  1098. Should be between 1 and 16384.
  1099. mcatest= [IA-64]
  1100. mce [X86-32] Machine Check Exception
  1101. mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
  1102. md= [HW] RAID subsystems devices and level
  1103. See Documentation/md.txt.
  1104. mdacon= [MDA]
  1105. Format: <first>,<last>
  1106. Specifies range of consoles to be captured by the MDA.
  1107. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  1108. Amount of memory to be used when the kernel is not able
  1109. to see the whole system memory or for test.
  1110. [X86-32] Use together with memmap= to avoid physical
  1111. address space collisions. Without memmap= PCI devices
  1112. could be placed at addresses belonging to unused RAM.
  1113. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  1114. memory.
  1115. memchunk=nn[KMG]
  1116. [KNL,SH] Allow user to override the default size for
  1117. per-device physically contiguous DMA buffers.
  1118. memmap=exactmap [KNL,X86] Enable setting of an exact
  1119. E820 memory map, as specified by the user.
  1120. Such memmap=exactmap lines can be constructed based on
  1121. BIOS output or other requirements. See the memmap=nn@ss
  1122. option description.
  1123. memmap=nn[KMG]@ss[KMG]
  1124. [KNL] Force usage of a specific region of memory
  1125. Region of memory to be used, from ss to ss+nn.
  1126. memmap=nn[KMG]#ss[KMG]
  1127. [KNL,ACPI] Mark specific memory as ACPI data.
  1128. Region of memory to be used, from ss to ss+nn.
  1129. memmap=nn[KMG]$ss[KMG]
  1130. [KNL,ACPI] Mark specific memory as reserved.
  1131. Region of memory to be used, from ss to ss+nn.
  1132. Example: Exclude memory from 0x18690000-0x1869ffff
  1133. memmap=64K$0x18690000
  1134. or
  1135. memmap=0x10000$0x18690000
  1136. memory_corruption_check=0/1 [X86]
  1137. Some BIOSes seem to corrupt the first 64k of
  1138. memory when doing things like suspend/resume.
  1139. Setting this option will scan the memory
  1140. looking for corruption. Enabling this will
  1141. both detect corruption and prevent the kernel
  1142. from using the memory being corrupted.
  1143. However, its intended as a diagnostic tool; if
  1144. repeatable BIOS-originated corruption always
  1145. affects the same memory, you can use memmap=
  1146. to prevent the kernel from using that memory.
  1147. memory_corruption_check_size=size [X86]
  1148. By default it checks for corruption in the low
  1149. 64k, making this memory unavailable for normal
  1150. use. Use this parameter to scan for
  1151. corruption in more or less memory.
  1152. memory_corruption_check_period=seconds [X86]
  1153. By default it checks for corruption every 60
  1154. seconds. Use this parameter to check at some
  1155. other rate. 0 disables periodic checking.
  1156. memtest= [KNL,X86] Enable memtest
  1157. Format: <integer>
  1158. default : 0 <disable>
  1159. Specifies the number of memtest passes to be
  1160. performed. Each pass selects another test
  1161. pattern from a given set of patterns. Memtest
  1162. fills the memory with this pattern, validates
  1163. memory contents and reserves bad memory
  1164. regions that are detected.
  1165. meye.*= [HW] Set MotionEye Camera parameters
  1166. See Documentation/video4linux/meye.txt.
  1167. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  1168. Multi-Function General Purpose Timers on AMD Geode
  1169. platforms.
  1170. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  1171. the BIOS has incorrectly applied a workaround. TinyBIOS
  1172. version 0.98 is known to be affected, 0.99 fixes the
  1173. problem by letting the user disable the workaround.
  1174. mga= [HW,DRM]
  1175. min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
  1176. physical address is ignored.
  1177. mini2440= [ARM,HW,KNL]
  1178. Format:[0..2][b][c][t]
  1179. Default: "0tb"
  1180. MINI2440 configuration specification:
  1181. 0 - The attached screen is the 3.5" TFT
  1182. 1 - The attached screen is the 7" TFT
  1183. 2 - The VGA Shield is attached (1024x768)
  1184. Leaving out the screen size parameter will not load
  1185. the TFT driver, and the framebuffer will be left
  1186. unconfigured.
  1187. b - Enable backlight. The TFT backlight pin will be
  1188. linked to the kernel VESA blanking code and a GPIO
  1189. LED. This parameter is not necessary when using the
  1190. VGA shield.
  1191. c - Enable the s3c camera interface.
  1192. t - Reserved for enabling touchscreen support. The
  1193. touchscreen support is not enabled in the mainstream
  1194. kernel as of 2.6.30, a preliminary port can be found
  1195. in the "bleeding edge" mini2440 support kernel at
  1196. http://repo.or.cz/w/linux-2.6/mini2440.git
  1197. mminit_loglevel=
  1198. [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
  1199. parameter allows control of the logging verbosity for
  1200. the additional memory initialisation checks. A value
  1201. of 0 disables mminit logging and a level of 4 will
  1202. log everything. Information is printed at KERN_DEBUG
  1203. so loglevel=8 may also need to be specified.
  1204. mousedev.tap_time=
  1205. [MOUSE] Maximum time between finger touching and
  1206. leaving touchpad surface for touch to be considered
  1207. a tap and be reported as a left button click (for
  1208. touchpads working in absolute mode only).
  1209. Format: <msecs>
  1210. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  1211. reporting absolute coordinates, such as tablets
  1212. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  1213. reporting absolute coordinates, such as tablets
  1214. movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  1215. is similar to kernelcore except it specifies the
  1216. amount of memory used for migratable allocations.
  1217. If both kernelcore and movablecore is specified,
  1218. then kernelcore will be at *least* the specified
  1219. value but may be more. If movablecore on its own
  1220. is specified, the administrator must be careful
  1221. that the amount of memory usable for all allocations
  1222. is not too small.
  1223. mpu401= [HW,OSS]
  1224. Format: <io>,<irq>
  1225. MTD_Partition= [MTD]
  1226. Format: <name>,<region-number>,<size>,<offset>
  1227. MTD_Region= [MTD] Format:
  1228. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  1229. mtdparts= [MTD]
  1230. See drivers/mtd/cmdlinepart.c.
  1231. onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
  1232. Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
  1233. boundary - index of last SLC block on Flex-OneNAND.
  1234. The remaining blocks are configured as MLC blocks.
  1235. lock - Configure if Flex-OneNAND boundary should be locked.
  1236. Once locked, the boundary cannot be changed.
  1237. 1 indicates lock status, 0 indicates unlock status.
  1238. mtdset= [ARM]
  1239. ARM/S3C2412 JIVE boot control
  1240. See arch/arm/mach-s3c2412/mach-jive.c
  1241. mtouchusb.raw_coordinates=
  1242. [HW] Make the MicroTouch USB driver use raw coordinates
  1243. ('y', default) or cooked coordinates ('n')
  1244. mtrr_chunk_size=nn[KMG] [X86]
  1245. used for mtrr cleanup. It is largest continuous chunk
  1246. that could hold holes aka. UC entries.
  1247. mtrr_gran_size=nn[KMG] [X86]
  1248. Used for mtrr cleanup. It is granularity of mtrr block.
  1249. Default is 1.
  1250. Large value could prevent small alignment from
  1251. using up MTRRs.
  1252. mtrr_spare_reg_nr=n [X86]
  1253. Format: <integer>
  1254. Range: 0,7 : spare reg number
  1255. Default : 1
  1256. Used for mtrr cleanup. It is spare mtrr entries number.
  1257. Set to 2 or more if your graphical card needs more.
  1258. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  1259. NCR_D700= [HW,SCSI]
  1260. See header of drivers/scsi/NCR_D700.c.
  1261. ncr5380= [HW,SCSI]
  1262. ncr53c400= [HW,SCSI]
  1263. ncr53c400a= [HW,SCSI]
  1264. ncr53c406a= [HW,SCSI]
  1265. ncr53c8xx= [HW,SCSI]
  1266. netdev= [NET] Network devices parameters
  1267. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  1268. Note that mem_start is often overloaded to mean
  1269. something different and driver-specific.
  1270. This usage is only documented in each driver source
  1271. file if at all.
  1272. nf_conntrack.acct=
  1273. [NETFILTER] Enable connection tracking flow accounting
  1274. 0 to disable accounting
  1275. 1 to enable accounting
  1276. Default value depends on CONFIG_NF_CT_ACCT that is
  1277. going to be removed in 2.6.29.
  1278. nfsaddrs= [NFS]
  1279. See Documentation/filesystems/nfs/nfsroot.txt.
  1280. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  1281. See Documentation/filesystems/nfs/nfsroot.txt.
  1282. nfs.callback_tcpport=
  1283. [NFS] set the TCP port on which the NFSv4 callback
  1284. channel should listen.
  1285. nfs.cache_getent=
  1286. [NFS] sets the pathname to the program which is used
  1287. to update the NFS client cache entries.
  1288. nfs.cache_getent_timeout=
  1289. [NFS] sets the timeout after which an attempt to
  1290. update a cache entry is deemed to have failed.
  1291. nfs.idmap_cache_timeout=
  1292. [NFS] set the maximum lifetime for idmapper cache
  1293. entries.
  1294. nfs.enable_ino64=
  1295. [NFS] enable 64-bit inode numbers.
  1296. If zero, the NFS client will fake up a 32-bit inode
  1297. number for the readdir() and stat() syscalls instead
  1298. of returning the full 64-bit number.
  1299. The default is to return 64-bit inode numbers.
  1300. nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
  1301. when a NMI is triggered.
  1302. Format: [state][,regs][,debounce][,die]
  1303. nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
  1304. Format: [panic,][num]
  1305. Valid num: 0,1,2
  1306. 0 - turn nmi_watchdog off
  1307. 1 - use the IO-APIC timer for the NMI watchdog
  1308. 2 - use the local APIC for the NMI watchdog using
  1309. a performance counter. Note: This will use one
  1310. performance counter and the local APIC's performance
  1311. vector.
  1312. When panic is specified, panic when an NMI watchdog
  1313. timeout occurs.
  1314. This is useful when you use a panic=... timeout and
  1315. need the box quickly up again.
  1316. Instead of 1 and 2 it is possible to use the following
  1317. symbolic names: lapic and ioapic
  1318. Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
  1319. netpoll.carrier_timeout=
  1320. [NET] Specifies amount of time (in seconds) that
  1321. netpoll should wait for a carrier. By default netpoll
  1322. waits 4 seconds.
  1323. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  1324. emulation library even if a 387 maths coprocessor
  1325. is present.
  1326. no_console_suspend
  1327. [HW] Never suspend the console
  1328. Disable suspending of consoles during suspend and
  1329. hibernate operations. Once disabled, debugging
  1330. messages can reach various consoles while the rest
  1331. of the system is being put to sleep (ie, while
  1332. debugging driver suspend/resume hooks). This may
  1333. not work reliably with all consoles, but is known
  1334. to work with serial and VGA consoles.
  1335. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  1336. caches in the slab allocator. Saves per-node memory,
  1337. but will impact performance.
  1338. noalign [KNL,ARM]
  1339. noapic [SMP,APIC] Tells the kernel to not make use of any
  1340. IOAPICs that may be present in the system.
  1341. nobats [PPC] Do not use BATs for mapping kernel lowmem
  1342. on "Classic" PPC cores.
  1343. nocache [ARM]
  1344. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  1345. nodelayacct [KNL] Disable per-task delay accounting
  1346. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  1347. nodsp [SH] Disable hardware DSP at boot time.
  1348. noefi [X86] Disable EFI runtime services support.
  1349. noexec [IA-64]
  1350. noexec [X86]
  1351. On X86-32 available only on PAE configured kernels.
  1352. noexec=on: enable non-executable mappings (default)
  1353. noexec=off: disable non-executable mappings
  1354. noexec32 [X86-64]
  1355. This affects only 32-bit executables.
  1356. noexec32=on: enable non-executable mappings (default)
  1357. read doesn't imply executable mappings
  1358. noexec32=off: disable non-executable mappings
  1359. read implies executable mappings
  1360. nofpu [SH] Disable hardware FPU at boot time.
  1361. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  1362. register save and restore. The kernel will only save
  1363. legacy floating-point registers on task switch.
  1364. noxsave [BUGS=X86] Disables x86 extended register state save
  1365. and restore using xsave. The kernel will fallback to
  1366. enabling legacy floating-point and sse state.
  1367. nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
  1368. wfi(ARM) instruction doesn't work correctly and not to
  1369. use it. This is also useful when using JTAG debugger.
  1370. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  1371. instruction doesn't work correctly and not to
  1372. use it.
  1373. no_file_caps Tells the kernel not to honor file capabilities. The
  1374. only way then for a file to be executed with privilege
  1375. is to be setuid root or executed by root.
  1376. nohalt [IA-64] Tells the kernel not to use the power saving
  1377. function PAL_HALT_LIGHT when idle. This increases
  1378. power-consumption. On the positive side, it reduces
  1379. interrupt wake-up latency, which may improve performance
  1380. in certain environments such as networked servers or
  1381. real-time systems.
  1382. nohz= [KNL] Boottime enable/disable dynamic ticks
  1383. Valid arguments: on, off
  1384. Default: on
  1385. noiotrap [SH] Disables trapped I/O port accesses.
  1386. noirqdebug [X86-32] Disables the code which attempts to detect and
  1387. disable unhandled interrupt sources.
  1388. no_timer_check [X86,APIC] Disables the code which tests for
  1389. broken timer IRQ sources.
  1390. noisapnp [ISAPNP] Disables ISA PnP code.
  1391. noinitrd [RAM] Tells the kernel not to load any configured
  1392. initial RAM disk.
  1393. nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
  1394. remapping.
  1395. nointroute [IA-64]
  1396. nojitter [IA64] Disables jitter checking for ITC timers.
  1397. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  1398. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  1399. noltlbs [PPC] Do not use large page/tlb entries for kernel
  1400. lowmem mapping on PPC40x.
  1401. nomca [IA-64] Disable machine check abort handling
  1402. nomce [X86-32] Machine Check Exception
  1403. nomfgpt [X86-32] Disable Multi-Function General Purpose
  1404. Timer usage (for AMD Geode machines).
  1405. nopat [X86] Disable PAT (page attribute table extension of
  1406. pagetables) support.
  1407. norandmaps Don't use address space randomization. Equivalent to
  1408. echo 0 > /proc/sys/kernel/randomize_va_space
  1409. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  1410. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1411. with UP alternatives
  1412. noresidual [PPC] Don't use residual data on PReP machines.
  1413. noresume [SWSUSP] Disables resume and restores original swap
  1414. space.
  1415. no-scroll [VGA] Disables scrollback.
  1416. This is required for the Braillex ib80-piezo Braille
  1417. reader made by F.H. Papenmeier (Germany).
  1418. nosbagart [IA-64]
  1419. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1420. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1421. and disable the IO APIC. legacy for "maxcpus=0".
  1422. nosoftlockup [KNL] Disable the soft-lockup detector.
  1423. noswapaccount [KNL] Disable accounting of swap in memory resource
  1424. controller. (See Documentation/cgroups/memory.txt)
  1425. nosync [HW,M68K] Disables sync negotiation for all devices.
  1426. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1427. nousb [USB] Disable the USB subsystem
  1428. nowb [ARM]
  1429. nox2apic [X86-64,APIC] Do not enable x2APIC mode.
  1430. nptcg= [IA64] Override max number of concurrent global TLB
  1431. purges which is reported from either PAL_VM_SUMMARY or
  1432. SAL PALO.
  1433. nr_cpus= [SMP] Maximum number of processors that an SMP kernel
  1434. could support. nr_cpus=n : n >= 1 limits the kernel to
  1435. supporting 'n' processors. Later in runtime you can not
  1436. use hotplug cpu feature to put more cpu back to online.
  1437. just like you compile the kernel NR_CPUS=n
  1438. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1439. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1440. one of ['zone', 'node', 'default'] can be specified
  1441. This can be set from sysctl after boot.
  1442. See Documentation/sysctl/vm.txt for details.
  1443. ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
  1444. See Documentation/debugging-via-ohci1394.txt for more
  1445. info.
  1446. olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
  1447. Rather than timing out after 20 ms if an EC
  1448. command is not properly ACKed, override the length
  1449. of the timeout. We have interrupts disabled while
  1450. waiting for the ACK, so if this is set too high
  1451. interrupts *may* be lost!
  1452. omap_mux= [OMAP] Override bootloader pin multiplexing.
  1453. Format: <mux_mode0.mode_name=value>...
  1454. For example, to override I2C bus2:
  1455. omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
  1456. opl3= [HW,OSS]
  1457. Format: <io>
  1458. oprofile.timer= [HW]
  1459. Use timer interrupt instead of performance counters
  1460. oprofile.cpu_type= Force an oprofile cpu type
  1461. This might be useful if you have an older oprofile
  1462. userland or if you want common events.
  1463. Format: { arch_perfmon }
  1464. arch_perfmon: [X86] Force use of architectural
  1465. perfmon on Intel CPUs instead of the
  1466. CPU specific event set.
  1467. osst= [HW,SCSI] SCSI Tape Driver
  1468. Format: <buffer_size>,<write_threshold>
  1469. See also Documentation/scsi/st.txt.
  1470. panic= [KNL] Kernel behaviour on panic
  1471. Format: <timeout>
  1472. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1473. connected to, default is 0.
  1474. Format: <parport#>
  1475. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1476. 0 for XT, 1 for AT (default is AT).
  1477. Format: <mode>
  1478. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1479. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1480. Use 'auto' to force the driver to use any
  1481. IRQ/DMA settings detected (the default is to
  1482. ignore detected IRQ/DMA settings because of
  1483. possible conflicts). You can specify the base
  1484. address, IRQ, and DMA settings; IRQ and DMA
  1485. should be numbers, or 'auto' (for using detected
  1486. settings on that particular port), or 'nofifo'
  1487. (to avoid using a FIFO even if it is detected).
  1488. Parallel ports are assigned in the order they
  1489. are specified on the command line, starting
  1490. with parport0.
  1491. parport_init_mode= [HW,PPT]
  1492. Configure VIA parallel port to operate in
  1493. a specific mode. This is necessary on Pegasos
  1494. computer where firmware has no options for setting
  1495. up parallel port mode and sets it to spp.
  1496. Currently this function knows 686a and 8231 chips.
  1497. Format: [spp|ps2|epp|ecp|ecpepp]
  1498. pas2= [HW,OSS] Format:
  1499. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1500. pas16= [HW,SCSI]
  1501. See header of drivers/scsi/pas16.c.
  1502. pause_on_oops=
  1503. Halt all CPUs after the first oops has been printed for
  1504. the specified number of seconds. This is to be used if
  1505. your oopses keep scrolling off the screen.
  1506. pcbit= [HW,ISDN]
  1507. pcd. [PARIDE]
  1508. See header of drivers/block/paride/pcd.c.
  1509. See also Documentation/blockdev/paride.txt.
  1510. pci=option[,option...] [PCI] various PCI subsystem options:
  1511. earlydump [X86] dump PCI config space before the kernel
  1512. changes anything
  1513. off [X86] don't probe for the PCI bus
  1514. bios [X86-32] force use of PCI BIOS, don't access
  1515. the hardware directly. Use this if your machine
  1516. has a non-standard PCI host bridge.
  1517. nobios [X86-32] disallow use of PCI BIOS, only direct
  1518. hardware access methods are allowed. Use this
  1519. if you experience crashes upon bootup and you
  1520. suspect they are caused by the BIOS.
  1521. conf1 [X86] Force use of PCI Configuration
  1522. Mechanism 1.
  1523. conf2 [X86] Force use of PCI Configuration
  1524. Mechanism 2.
  1525. noaer [PCIE] If the PCIEAER kernel config parameter is
  1526. enabled, this kernel boot option can be used to
  1527. disable the use of PCIE advanced error reporting.
  1528. nodomains [PCI] Disable support for multiple PCI
  1529. root domains (aka PCI segments, in ACPI-speak).
  1530. nommconf [X86] Disable use of MMCONFIG for PCI
  1531. Configuration
  1532. check_enable_amd_mmconf [X86] check for and enable
  1533. properly configured MMIO access to PCI
  1534. config space on AMD family 10h CPU
  1535. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1536. enabled, this kernel boot option can be used to
  1537. disable the use of MSI interrupts system-wide.
  1538. noioapicquirk [APIC] Disable all boot interrupt quirks.
  1539. Safety option to keep boot IRQs enabled. This
  1540. should never be necessary.
  1541. ioapicreroute [APIC] Enable rerouting of boot IRQs to the
  1542. primary IO-APIC for bridges that cannot disable
  1543. boot IRQs. This fixes a source of spurious IRQs
  1544. when the system masks IRQs.
  1545. noioapicreroute [APIC] Disable workaround that uses the
  1546. boot IRQ equivalent of an IRQ that connects to
  1547. a chipset where boot IRQs cannot be disabled.
  1548. The opposite of ioapicreroute.
  1549. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1550. routing table. These calls are known to be buggy
  1551. on several machines and they hang the machine
  1552. when used, but on other computers it's the only
  1553. way to get the interrupt routing table. Try
  1554. this option if the kernel is unable to allocate
  1555. IRQs or discover secondary PCI buses on your
  1556. motherboard.
  1557. rom [X86] Assign address space to expansion ROMs.
  1558. Use with caution as certain devices share
  1559. address decoders between ROMs and other
  1560. resources.
  1561. norom [X86] Do not assign address space to
  1562. expansion ROMs that do not already have
  1563. BIOS assigned address ranges.
  1564. irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
  1565. assigned automatically to PCI devices. You can
  1566. make the kernel exclude IRQs of your ISA cards
  1567. this way.
  1568. pirqaddr=0xAAAAA [X86] Specify the physical address
  1569. of the PIRQ table (normally generated
  1570. by the BIOS) if it is outside the
  1571. F0000h-100000h range.
  1572. lastbus=N [X86] Scan all buses thru bus #N. Can be
  1573. useful if the kernel is unable to find your
  1574. secondary buses and you want to tell it
  1575. explicitly which ones they are.
  1576. assign-busses [X86] Always assign all PCI bus
  1577. numbers ourselves, overriding
  1578. whatever the firmware may have done.
  1579. usepirqmask [X86] Honor the possible IRQ mask stored
  1580. in the BIOS $PIR table. This is needed on
  1581. some systems with broken BIOSes, notably
  1582. some HP Pavilion N5400 and Omnibook XE3
  1583. notebooks. This will have no effect if ACPI
  1584. IRQ routing is enabled.
  1585. noacpi [X86] Do not use ACPI for IRQ routing
  1586. or for PCI scanning.
  1587. use_crs [X86] Use PCI host bridge window information
  1588. from ACPI. On BIOSes from 2008 or later, this
  1589. is enabled by default. If you need to use this,
  1590. please report a bug.
  1591. nocrs [X86] Ignore PCI host bridge windows from ACPI.
  1592. If you need to use this, please report a bug.
  1593. routeirq Do IRQ routing for all PCI devices.
  1594. This is normally done in pci_enable_device(),
  1595. so this option is a temporary workaround
  1596. for broken drivers that don't call it.
  1597. skip_isa_align [X86] do not align io start addr, so can
  1598. handle more pci cards
  1599. firmware [ARM] Do not re-enumerate the bus but instead
  1600. just use the configuration from the
  1601. bootloader. This is currently used on
  1602. IXP2000 systems where the bus has to be
  1603. configured a certain way for adjunct CPUs.
  1604. noearly [X86] Don't do any early type 1 scanning.
  1605. This might help on some broken boards which
  1606. machine check when some devices' config space
  1607. is read. But various workarounds are disabled
  1608. and some IOMMU drivers will not work.
  1609. bfsort Sort PCI devices into breadth-first order.
  1610. This sorting is done to get a device
  1611. order compatible with older (<= 2.4) kernels.
  1612. nobfsort Don't sort PCI devices into breadth-first order.
  1613. cbiosize=nn[KMG] The fixed amount of bus space which is
  1614. reserved for the CardBus bridge's IO window.
  1615. The default value is 256 bytes.
  1616. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1617. reserved for the CardBus bridge's memory
  1618. window. The default value is 64 megabytes.
  1619. resource_alignment=
  1620. Format:
  1621. [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
  1622. Specifies alignment and device to reassign
  1623. aligned memory resources.
  1624. If <order of align> is not specified,
  1625. PAGE_SIZE is used as alignment.
  1626. PCI-PCI bridge can be specified, if resource
  1627. windows need to be expanded.
  1628. ecrc= Enable/disable PCIe ECRC (transaction layer
  1629. end-to-end CRC checking).
  1630. bios: Use BIOS/firmware settings. This is the
  1631. the default.
  1632. off: Turn ECRC off
  1633. on: Turn ECRC on.
  1634. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
  1635. Management.
  1636. off Disable ASPM.
  1637. force Enable ASPM even on devices that claim not to support it.
  1638. WARNING: Forcing ASPM on may cause system lockups.
  1639. pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
  1640. off Do not use native PCIe PME signaling.
  1641. force Use native PCIe PME signaling even if the BIOS refuses
  1642. to allow the kernel to control the relevant PCIe config
  1643. registers.
  1644. nomsi Do not use MSI for native PCIe PME signaling (this makes
  1645. all PCIe root ports use INTx for everything).
  1646. pcmv= [HW,PCMCIA] BadgePAD 4
  1647. pd. [PARIDE]
  1648. See Documentation/blockdev/paride.txt.
  1649. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1650. boot time.
  1651. Format: { 0 | 1 }
  1652. See arch/parisc/kernel/pdc_chassis.c
  1653. percpu_alloc= Select which percpu first chunk allocator to use.
  1654. Currently supported values are "embed" and "page".
  1655. Archs may support subset or none of the selections.
  1656. See comments in mm/percpu.c for details on each
  1657. allocator. This parameter is primarily for debugging
  1658. and performance comparison.
  1659. pf. [PARIDE]
  1660. See Documentation/blockdev/paride.txt.
  1661. pg. [PARIDE]
  1662. See Documentation/blockdev/paride.txt.
  1663. pirq= [SMP,APIC] Manual mp-table setup
  1664. See Documentation/x86/i386/IO-APIC.txt.
  1665. plip= [PPT,NET] Parallel port network link
  1666. Format: { parport<nr> | timid | 0 }
  1667. See also Documentation/parport.txt.
  1668. pmtmr= [X86] Manual setup of pmtmr I/O Port.
  1669. Override pmtimer IOPort with a hex value.
  1670. e.g. pmtmr=0x508
  1671. pnp.debug [PNP]
  1672. Enable PNP debug messages. This depends on the
  1673. CONFIG_PNP_DEBUG_MESSAGES option.
  1674. pnpacpi= [ACPI]
  1675. { off }
  1676. pnpbios= [ISAPNP]
  1677. { on | off | curr | res | no-curr | no-res }
  1678. pnp_reserve_irq=
  1679. [ISAPNP] Exclude IRQs for the autoconfiguration
  1680. pnp_reserve_dma=
  1681. [ISAPNP] Exclude DMAs for the autoconfiguration
  1682. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1683. Ranges are in pairs (I/O port base and size).
  1684. pnp_reserve_mem=
  1685. [ISAPNP] Exclude memory regions for the
  1686. autoconfiguration.
  1687. Ranges are in pairs (memory base and size).
  1688. ports= [IP_VS_FTP] IPVS ftp helper module
  1689. Default is 21.
  1690. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  1691. may be specified.
  1692. Format: <port>,<port>....
  1693. print-fatal-signals=
  1694. [KNL] debug: print fatal signals
  1695. If enabled, warn about various signal handling
  1696. related application anomalies: too many signals,
  1697. too many POSIX.1 timers, fatal signals causing a
  1698. coredump - etc.
  1699. If you hit the warning due to signal overflow,
  1700. you might want to try "ulimit -i unlimited".
  1701. default: off.
  1702. printk.time= Show timing data prefixed to each printk message line
  1703. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1704. processor.max_cstate= [HW,ACPI]
  1705. Limit processor to maximum C-state
  1706. max_cstate=9 overrides any DMI blacklist limit.
  1707. processor.nocst [HW,ACPI]
  1708. Ignore the _CST method to determine C-states,
  1709. instead using the legacy FADT method
  1710. profile= [KNL] Enable kernel profiling via /proc/profile
  1711. Format: [schedule,]<number>
  1712. Param: "schedule" - profile schedule points.
  1713. Param: <number> - step/bucket size as a power of 2 for
  1714. statistical time based profiling.
  1715. Param: "sleep" - profile D-state sleeping (millisecs).
  1716. Requires CONFIG_SCHEDSTATS
  1717. Param: "kvm" - profile VM exits.
  1718. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1719. before loading.
  1720. See Documentation/blockdev/ramdisk.txt.
  1721. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1722. probe for; one of (bare|imps|exps|lifebook|any).
  1723. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1724. per second.
  1725. psmouse.resetafter= [HW,MOUSE]
  1726. Try to reset the device after so many bad packets
  1727. (0 = never).
  1728. psmouse.resolution=
  1729. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1730. psmouse.smartscroll=
  1731. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1732. 0 = disabled, 1 = enabled (default).
  1733. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1734. Format:
  1735. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1736. pt. [PARIDE]
  1737. See Documentation/blockdev/paride.txt.
  1738. pty.legacy_count=
  1739. [KNL] Number of legacy pty's. Overwrites compiled-in
  1740. default number.
  1741. quiet [KNL] Disable most log messages
  1742. r128= [HW,DRM]
  1743. raid= [HW,RAID]
  1744. See Documentation/md.txt.
  1745. ramdisk_blocksize= [RAM]
  1746. See Documentation/blockdev/ramdisk.txt.
  1747. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1748. See Documentation/blockdev/ramdisk.txt.
  1749. rcupdate.blimit= [KNL,BOOT]
  1750. Set maximum number of finished RCU callbacks to process
  1751. in one batch.
  1752. rcupdate.qhimark= [KNL,BOOT]
  1753. Set threshold of queued
  1754. RCU callbacks over which batch limiting is disabled.
  1755. rcupdate.qlowmark= [KNL,BOOT]
  1756. Set threshold of queued RCU callbacks below which
  1757. batch limiting is re-enabled.
  1758. rdinit= [KNL]
  1759. Format: <full_path>
  1760. Run specified binary instead of /init from the ramdisk,
  1761. used for early userspace startup. See initrd.
  1762. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1763. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1764. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1765. relax_domain_level=
  1766. [KNL, SMP] Set scheduler's default relax_domain_level.
  1767. See Documentation/cgroups/cpusets.txt.
  1768. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1769. reservetop= [X86-32]
  1770. Format: nn[KMG]
  1771. Reserves a hole at the top of the kernel virtual
  1772. address space.
  1773. reset_devices [KNL] Force drivers to reset the underlying device
  1774. during initialization.
  1775. resume= [SWSUSP]
  1776. Specify the partition device for software suspend
  1777. resume_offset= [SWSUSP]
  1778. Specify the offset from the beginning of the partition
  1779. given by "resume=" at which the swap header is located,
  1780. in <PAGE_SIZE> units (needed only for swap files).
  1781. See Documentation/power/swsusp-and-swap-files.txt
  1782. retain_initrd [RAM] Keep initrd memory after extraction
  1783. rhash_entries= [KNL,NET]
  1784. Set number of hash buckets for route cache
  1785. riscom8= [HW,SERIAL]
  1786. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1787. ro [KNL] Mount root device read-only on boot
  1788. root= [KNL] Root filesystem
  1789. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1790. mount the root filesystem
  1791. rootflags= [KNL] Set root filesystem mount option string
  1792. rootfstype= [KNL] Set root filesystem type
  1793. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1794. Useful for devices that are detected asynchronously
  1795. (e.g. USB and MMC devices).
  1796. rw [KNL] Mount root device read-write on boot
  1797. S [KNL] Run init in single mode
  1798. sa1100ir [NET]
  1799. See drivers/net/irda/sa1100_ir.c.
  1800. sbni= [NET] Granch SBNI12 leased line adapter
  1801. sched_debug [KNL] Enables verbose scheduler debug messages.
  1802. scsi_debug_*= [SCSI]
  1803. See drivers/scsi/scsi_debug.c.
  1804. scsi_default_dev_flags=
  1805. [SCSI] SCSI default device flags
  1806. Format: <integer>
  1807. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1808. Format: <vendor>:<model>:<flags>
  1809. (flags are integer value)
  1810. scsi_logging_level= [SCSI] a bit mask of logging levels
  1811. See drivers/scsi/scsi_logging.h for bits. Also
  1812. settable via sysctl at dev.scsi.logging_level
  1813. (/proc/sys/dev/scsi/logging_level).
  1814. There is also a nice 'scsi_logging_level' script in the
  1815. S390-tools package, available for download at
  1816. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1817. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1818. discovered. async scans them in kernel threads,
  1819. allowing boot to proceed. none ignores them, expecting
  1820. user space to do the scan.
  1821. security= [SECURITY] Choose a security module to enable at boot.
  1822. If this boot parameter is not specified, only the first
  1823. security module asking for security registration will be
  1824. loaded. An invalid security module name will be treated
  1825. as if no module has been chosen.
  1826. selinux= [SELINUX] Disable or enable SELinux at boot time.
  1827. Format: { "0" | "1" }
  1828. See security/selinux/Kconfig help text.
  1829. 0 -- disable.
  1830. 1 -- enable.
  1831. Default value is set via kernel config option.
  1832. If enabled at boot time, /selinux/disable can be used
  1833. later to disable prior to initial policy load.
  1834. serialnumber [BUGS=X86-32]
  1835. shapers= [NET]
  1836. Maximal number of shapers.
  1837. show_msr= [x86] show boot-time MSR settings
  1838. Format: { <integer> }
  1839. Show boot-time (BIOS-initialized) MSR settings.
  1840. The parameter means the number of CPUs to show,
  1841. for example 1 means boot CPU only.
  1842. sim710= [SCSI,HW]
  1843. See header of drivers/scsi/sim710.c.
  1844. simeth= [IA-64]
  1845. simscsi=
  1846. slram= [HW,MTD]
  1847. slub_debug[=options[,slabs]] [MM, SLUB]
  1848. Enabling slub_debug allows one to determine the
  1849. culprit if slab objects become corrupted. Enabling
  1850. slub_debug can create guard zones around objects and
  1851. may poison objects when not in use. Also tracks the
  1852. last alloc / free. For more information see
  1853. Documentation/vm/slub.txt.
  1854. slub_max_order= [MM, SLUB]
  1855. Determines the maximum allowed order for slabs.
  1856. A high setting may cause OOMs due to memory
  1857. fragmentation. For more information see
  1858. Documentation/vm/slub.txt.
  1859. slub_min_objects= [MM, SLUB]
  1860. The minimum number of objects per slab. SLUB will
  1861. increase the slab order up to slub_max_order to
  1862. generate a sufficiently large slab able to contain
  1863. the number of objects indicated. The higher the number
  1864. of objects the smaller the overhead of tracking slabs
  1865. and the less frequently locks need to be acquired.
  1866. For more information see Documentation/vm/slub.txt.
  1867. slub_min_order= [MM, SLUB]
  1868. Determines the mininum page order for slabs. Must be
  1869. lower than slub_max_order.
  1870. For more information see Documentation/vm/slub.txt.
  1871. slub_nomerge [MM, SLUB]
  1872. Disable merging of slabs with similar size. May be
  1873. necessary if there is some reason to distinguish
  1874. allocs to different slabs. Debug options disable
  1875. merging on their own.
  1876. For more information see Documentation/vm/slub.txt.
  1877. smart2= [HW]
  1878. Format: <io1>[,<io2>[,...,<io8>]]
  1879. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1880. attempt to substitute SMP alternatives once at boot.
  1881. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1882. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1883. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1884. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1885. smsc-ircc2.ircc_irq= [HW] IRQ line
  1886. smsc-ircc2.ircc_dma= [HW] DMA channel
  1887. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1888. 0: Toshiba Satellite 1800 (GP data pin select)
  1889. 1: Fast pin select (default)
  1890. 2: ATC IRMode
  1891. snd-ad1816a= [HW,ALSA]
  1892. snd-ad1848= [HW,ALSA]
  1893. snd-ali5451= [HW,ALSA]
  1894. snd-als100= [HW,ALSA]
  1895. snd-als4000= [HW,ALSA]
  1896. snd-azt2320= [HW,ALSA]
  1897. snd-cmi8330= [HW,ALSA]
  1898. snd-cmipci= [HW,ALSA]
  1899. snd-cs4231= [HW,ALSA]
  1900. snd-cs4232= [HW,ALSA]
  1901. snd-cs4236= [HW,ALSA]
  1902. snd-cs4281= [HW,ALSA]
  1903. snd-cs46xx= [HW,ALSA]
  1904. snd-dt019x= [HW,ALSA]
  1905. snd-dummy= [HW,ALSA]
  1906. snd-emu10k1= [HW,ALSA]
  1907. snd-ens1370= [HW,ALSA]
  1908. snd-ens1371= [HW,ALSA]
  1909. snd-es968= [HW,ALSA]
  1910. snd-es1688= [HW,ALSA]
  1911. snd-es18xx= [HW,ALSA]
  1912. snd-es1938= [HW,ALSA]
  1913. snd-es1968= [HW,ALSA]
  1914. snd-fm801= [HW,ALSA]
  1915. snd-gusclassic= [HW,ALSA]
  1916. snd-gusextreme= [HW,ALSA]
  1917. snd-gusmax= [HW,ALSA]
  1918. snd-hdsp= [HW,ALSA]
  1919. snd-ice1712= [HW,ALSA]
  1920. snd-intel8x0= [HW,ALSA]
  1921. snd-interwave= [HW,ALSA]
  1922. snd-interwave-stb=
  1923. [HW,ALSA]
  1924. snd-korg1212= [HW,ALSA]
  1925. snd-maestro3= [HW,ALSA]
  1926. snd-mpu401= [HW,ALSA]
  1927. snd-mtpav= [HW,ALSA]
  1928. snd-nm256= [HW,ALSA]
  1929. snd-opl3sa2= [HW,ALSA]
  1930. snd-opti92x-ad1848=
  1931. [HW,ALSA]
  1932. snd-opti92x-cs4231=
  1933. [HW,ALSA]
  1934. snd-opti93x= [HW,ALSA]
  1935. snd-pmac= [HW,ALSA]
  1936. snd-rme32= [HW,ALSA]
  1937. snd-rme96= [HW,ALSA]
  1938. snd-rme9652= [HW,ALSA]
  1939. snd-sb8= [HW,ALSA]
  1940. snd-sb16= [HW,ALSA]
  1941. snd-sbawe= [HW,ALSA]
  1942. snd-serial= [HW,ALSA]
  1943. snd-sgalaxy= [HW,ALSA]
  1944. snd-sonicvibes= [HW,ALSA]
  1945. snd-sun-amd7930=
  1946. [HW,ALSA]
  1947. snd-sun-cs4231= [HW,ALSA]
  1948. snd-trident= [HW,ALSA]
  1949. snd-usb-audio= [HW,ALSA,USB]
  1950. snd-via82xx= [HW,ALSA]
  1951. snd-virmidi= [HW,ALSA]
  1952. snd-wavefront= [HW,ALSA]
  1953. snd-ymfpci= [HW,ALSA]
  1954. softlockup_panic=
  1955. [KNL] Should the soft-lockup detector generate panics.
  1956. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1957. See Documentation/sonypi.txt
  1958. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1959. See Documentation/serial/specialix.txt.
  1960. spia_io_base= [HW,MTD]
  1961. spia_fio_base=
  1962. spia_pedr=
  1963. spia_peddr=
  1964. sscape= [HW,OSS]
  1965. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1966. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1967. See Documentation/scsi/st.txt.
  1968. stacktrace [FTRACE]
  1969. Enabled the stack tracer on boot up.
  1970. sti= [PARISC,HW]
  1971. Format: <num>
  1972. Set the STI (builtin display/keyboard on the HP-PARISC
  1973. machines) console (graphic card) which should be used
  1974. as the initial boot-console.
  1975. See also comment in drivers/video/console/sticore.c.
  1976. sti_font= [HW]
  1977. See comment in drivers/video/console/sticore.c.
  1978. stifb= [HW]
  1979. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1980. sunrpc.min_resvport=
  1981. sunrpc.max_resvport=
  1982. [NFS,SUNRPC]
  1983. SunRPC servers often require that client requests
  1984. originate from a privileged port (i.e. a port in the
  1985. range 0 < portnr < 1024).
  1986. An administrator who wishes to reserve some of these
  1987. ports for other uses may adjust the range that the
  1988. kernel's sunrpc client considers to be privileged
  1989. using these two parameters to set the minimum and
  1990. maximum port values.
  1991. sunrpc.pool_mode=
  1992. [NFS]
  1993. Control how the NFS server code allocates CPUs to
  1994. service thread pools. Depending on how many NICs
  1995. you have and where their interrupts are bound, this
  1996. option will affect which CPUs will do NFS serving.
  1997. Note: this parameter cannot be changed while the
  1998. NFS server is running.
  1999. auto the server chooses an appropriate mode
  2000. automatically using heuristics
  2001. global a single global pool contains all CPUs
  2002. percpu one pool for each CPU
  2003. pernode one pool for each NUMA node (equivalent
  2004. to global on non-NUMA machines)
  2005. sunrpc.tcp_slot_table_entries=
  2006. sunrpc.udp_slot_table_entries=
  2007. [NFS,SUNRPC]
  2008. Sets the upper limit on the number of simultaneous
  2009. RPC calls that can be sent from the client to a
  2010. server. Increasing these values may allow you to
  2011. improve throughput, but will also increase the
  2012. amount of memory reserved for use by the client.
  2013. swiotlb= [IA-64] Number of I/O TLB slabs
  2014. switches= [HW,M68k]
  2015. sym53c416= [HW,SCSI]
  2016. See header of drivers/scsi/sym53c416.c.
  2017. sysrq_always_enabled
  2018. [KNL]
  2019. Ignore sysrq setting - this boot parameter will
  2020. neutralize any effect of /proc/sys/kernel/sysrq.
  2021. Useful for debugging.
  2022. t128= [HW,SCSI]
  2023. See header of drivers/scsi/t128.c.
  2024. tdfx= [HW,DRM]
  2025. test_suspend= [SUSPEND]
  2026. Specify "mem" (for Suspend-to-RAM) or "standby" (for
  2027. standby suspend) as the system sleep state to briefly
  2028. enter during system startup. The system is woken from
  2029. this state using a wakeup-capable RTC alarm.
  2030. thash_entries= [KNL,NET]
  2031. Set number of hash buckets for TCP connection
  2032. thermal.act= [HW,ACPI]
  2033. -1: disable all active trip points in all thermal zones
  2034. <degrees C>: override all lowest active trip points
  2035. thermal.crt= [HW,ACPI]
  2036. -1: disable all critical trip points in all thermal zones
  2037. <degrees C>: override all critical trip points
  2038. thermal.nocrt= [HW,ACPI]
  2039. Set to disable actions on ACPI thermal zone
  2040. critical and hot trip points.
  2041. thermal.off= [HW,ACPI]
  2042. 1: disable ACPI thermal control
  2043. thermal.psv= [HW,ACPI]
  2044. -1: disable all passive trip points
  2045. <degrees C>: override all passive trip points to this
  2046. value
  2047. thermal.tzp= [HW,ACPI]
  2048. Specify global default ACPI thermal zone polling rate
  2049. <deci-seconds>: poll all this frequency
  2050. 0: no polling (default)
  2051. tmscsim= [HW,SCSI]
  2052. See comment before function dc390_setup() in
  2053. drivers/scsi/tmscsim.c.
  2054. topology= [S390]
  2055. Format: {off | on}
  2056. Specify if the kernel should make use of the cpu
  2057. topology informations if the hardware supports these.
  2058. The scheduler will make use of these informations and
  2059. e.g. base its process migration decisions on it.
  2060. Default is off.
  2061. tp720= [HW,PS2]
  2062. tpm_suspend_pcr=[HW,TPM]
  2063. Format: integer pcr id
  2064. Specify that at suspend time, the tpm driver
  2065. should extend the specified pcr with zeros,
  2066. as a workaround for some chips which fail to
  2067. flush the last written pcr on TPM_SaveState.
  2068. This will guarantee that all the other pcrs
  2069. are saved.
  2070. trace_buf_size=nn[KMG]
  2071. [FTRACE] will set tracing buffer size.
  2072. trace_event=[event-list]
  2073. [FTRACE] Set and start specified trace events in order
  2074. to facilitate early boot debugging.
  2075. See also Documentation/trace/events.txt
  2076. trix= [HW,OSS] MediaTrix AudioTrix Pro
  2077. Format:
  2078. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  2079. tsc= Disable clocksource-must-verify flag for TSC.
  2080. Format: <string>
  2081. [x86] reliable: mark tsc clocksource as reliable, this
  2082. disables clocksource verification at runtime.
  2083. Used to enable high-resolution timer mode on older
  2084. hardware, and in virtualized environment.
  2085. turbografx.map[2|3]= [HW,JOY]
  2086. TurboGraFX parallel port interface
  2087. Format:
  2088. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  2089. See also Documentation/input/joystick-parport.txt
  2090. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  2091. See header of drivers/scsi/u14-34f.c.
  2092. uart401= [HW,OSS]
  2093. Format: <io>,<irq>
  2094. uart6850= [HW,OSS]
  2095. Format: <io>,<irq>
  2096. uhash_entries= [KNL,NET]
  2097. Set number of hash buckets for UDP/UDP-Lite connections
  2098. uhci-hcd.ignore_oc=
  2099. [USB] Ignore overcurrent events (default N).
  2100. Some badly-designed motherboards generate lots of
  2101. bogus events, for ports that aren't wired to
  2102. anything. Set this parameter to avoid log spamming.
  2103. Note that genuine overcurrent events won't be
  2104. reported either.
  2105. unknown_nmi_panic
  2106. [X86]
  2107. Set unknown_nmi_panic=1 early on boot.
  2108. usbcore.autosuspend=
  2109. [USB] The autosuspend time delay (in seconds) used
  2110. for newly-detected USB devices (default 2). This
  2111. is the time required before an idle device will be
  2112. autosuspended. Devices for which the delay is set
  2113. to a negative value won't be autosuspended at all.
  2114. usbcore.usbfs_snoop=
  2115. [USB] Set to log all usbfs traffic (default 0 = off).
  2116. usbcore.blinkenlights=
  2117. [USB] Set to cycle leds on hubs (default 0 = off).
  2118. usbcore.old_scheme_first=
  2119. [USB] Start with the old device initialization
  2120. scheme (default 0 = off).
  2121. usbcore.use_both_schemes=
  2122. [USB] Try the other device initialization scheme
  2123. if the first one fails (default 1 = enabled).
  2124. usbcore.initial_descriptor_timeout=
  2125. [USB] Specifies timeout for the initial 64-byte
  2126. USB_REQ_GET_DESCRIPTOR request in milliseconds
  2127. (default 5000 = 5.0 seconds).
  2128. usbhid.mousepoll=
  2129. [USBHID] The interval which mice are to be polled at.
  2130. usb-storage.delay_use=
  2131. [UMS] The delay in seconds before a new device is
  2132. scanned for Logical Units (default 5).
  2133. usb-storage.quirks=
  2134. [UMS] A list of quirks entries to supplement or
  2135. override the built-in unusual_devs list. List
  2136. entries are separated by commas. Each entry has
  2137. the form VID:PID:Flags where VID and PID are Vendor
  2138. and Product ID values (4-digit hex numbers) and
  2139. Flags is a set of characters, each corresponding
  2140. to a common usb-storage quirk flag as follows:
  2141. a = SANE_SENSE (collect more than 18 bytes
  2142. of sense data);
  2143. b = BAD_SENSE (don't collect more than 18
  2144. bytes of sense data);
  2145. c = FIX_CAPACITY (decrease the reported
  2146. device capacity by one sector);
  2147. h = CAPACITY_HEURISTICS (decrease the
  2148. reported device capacity by one
  2149. sector if the number is odd);
  2150. i = IGNORE_DEVICE (don't bind to this
  2151. device);
  2152. l = NOT_LOCKABLE (don't try to lock and
  2153. unlock ejectable media);
  2154. m = MAX_SECTORS_64 (don't transfer more
  2155. than 64 sectors = 32 KB at a time);
  2156. o = CAPACITY_OK (accept the capacity
  2157. reported by the device);
  2158. r = IGNORE_RESIDUE (the device reports
  2159. bogus residue values);
  2160. s = SINGLE_LUN (the device has only one
  2161. Logical Unit);
  2162. w = NO_WP_DETECT (don't test whether the
  2163. medium is write-protected).
  2164. Example: quirks=0419:aaf5:rl,0421:0433:rc
  2165. userpte=
  2166. [X86] Flags controlling user PTE allocations.
  2167. nohigh = do not allocate PTE pages in
  2168. HIGHMEM regardless of setting
  2169. of CONFIG_HIGHPTE.
  2170. vdso= [X86,SH]
  2171. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  2172. vdso=1: enable VDSO (default)
  2173. vdso=0: disable VDSO mapping
  2174. vdso32= [X86]
  2175. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  2176. vdso32=1: enable 32-bit VDSO (default)
  2177. vdso32=0: disable 32-bit VDSO mapping
  2178. vector= [IA-64,SMP]
  2179. vector=percpu: enable percpu vector domain
  2180. video= [FB] Frame buffer configuration
  2181. See Documentation/fb/modedb.txt.
  2182. vga= [BOOT,X86-32] Select a particular video mode
  2183. See Documentation/x86/boot.txt and
  2184. Documentation/svga.txt.
  2185. Use vga=ask for menu.
  2186. This is actually a boot loader parameter; the value is
  2187. passed to the kernel using a special protocol.
  2188. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  2189. size of <nn>. This can be used to increase the
  2190. minimum size (128MB on x86). It can also be used to
  2191. decrease the size and leave more room for directly
  2192. mapped kernel RAM.
  2193. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  2194. Format: <command>
  2195. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  2196. Format: <command>
  2197. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  2198. Format: <command>
  2199. vt.cur_default= [VT] Default cursor shape.
  2200. Format: 0xCCBBAA, where AA, BB, and CC are the same as
  2201. the parameters of the <Esc>[?A;B;Cc escape sequence;
  2202. see VGA-softcursor.txt. Default: 2 = underline.
  2203. vt.default_blu= [VT]
  2204. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  2205. Change the default blue palette of the console.
  2206. This is a 16-member array composed of values
  2207. ranging from 0-255.
  2208. vt.default_grn= [VT]
  2209. Format: <green0>,<green1>,<green2>,...,<green15>
  2210. Change the default green palette of the console.
  2211. This is a 16-member array composed of values
  2212. ranging from 0-255.
  2213. vt.default_red= [VT]
  2214. Format: <red0>,<red1>,<red2>,...,<red15>
  2215. Change the default red palette of the console.
  2216. This is a 16-member array composed of values
  2217. ranging from 0-255.
  2218. vt.default_utf8=
  2219. [VT]
  2220. Format=<0|1>
  2221. Set system-wide default UTF-8 mode for all tty's.
  2222. Default is 1, i.e. UTF-8 mode is enabled for all
  2223. newly opened terminals.
  2224. vt.global_cursor_default=
  2225. [VT]
  2226. Format=<-1|0|1>
  2227. Set system-wide default for whether a cursor
  2228. is shown on new VTs. Default is -1,
  2229. i.e. cursors will be created by default unless
  2230. overridden by individual drivers. 0 will hide
  2231. cursors, 1 will display them.
  2232. waveartist= [HW,OSS]
  2233. Format: <io>,<irq>,<dma>,<dma2>
  2234. wd33c93= [HW,SCSI]
  2235. See header of drivers/scsi/wd33c93.c.
  2236. wd7000= [HW,SCSI]
  2237. See header of drivers/scsi/wd7000.c.
  2238. watchdog timers [HW,WDT] For information on watchdog timers,
  2239. see Documentation/watchdog/watchdog-parameters.txt
  2240. or other driver-specific files in the
  2241. Documentation/watchdog/ directory.
  2242. x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
  2243. default x2apic cluster mode on platforms
  2244. supporting x2apic.
  2245. x86_mrst_timer= [X86-32,APBT]
  2246. Choose timer option for x86 Moorestown MID platform.
  2247. Two valid options are apbt timer only and lapic timer
  2248. plus one apbt timer for broadcast timer.
  2249. x86_mrst_timer=apbt_only | lapic_and_apbt
  2250. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  2251. xd_geo= See header of drivers/block/xd.c.
  2252. xirc2ps_cs= [NET,PCMCIA]
  2253. Format:
  2254. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  2255. ______________________________________________________________________
  2256. TODO:
  2257. Add documentation for ALSA options.
  2258. Add more DRM drivers.