kernel-parameters.txt 85 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. ISAPNP ISA PnP code is enabled.
  48. ISDN Appropriate ISDN support is enabled.
  49. JOY Appropriate joystick support is enabled.
  50. LIBATA Libata driver is enabled
  51. LP Printer support is enabled.
  52. LOOP Loopback device support is enabled.
  53. M68k M68k architecture is enabled.
  54. These options have more detailed description inside of
  55. Documentation/m68k/kernel-options.txt.
  56. MCA MCA bus support is enabled.
  57. MDA MDA console support is enabled.
  58. MOUSE Appropriate mouse support is enabled.
  59. MSI Message Signaled Interrupts (PCI).
  60. MTD MTD (Memory Technology Device) support is enabled.
  61. NET Appropriate network support is enabled.
  62. NUMA NUMA support is enabled.
  63. GENERIC_TIME The generic timeofday code is enabled.
  64. NFS Appropriate NFS support is enabled.
  65. OSS OSS sound support is enabled.
  66. PV_OPS A paravirtualized kernel is enabled.
  67. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  68. PARISC The PA-RISC architecture is enabled.
  69. PCI PCI bus support is enabled.
  70. PCIE PCI Express support is enabled.
  71. PCMCIA The PCMCIA subsystem is enabled.
  72. PNP Plug & Play support is enabled.
  73. PPC PowerPC architecture is enabled.
  74. PPT Parallel port support is enabled.
  75. PS2 Appropriate PS/2 support is enabled.
  76. RAM RAM disk support is enabled.
  77. ROOTPLUG The example Root Plug LSM is enabled.
  78. S390 S390 architecture is enabled.
  79. SCSI Appropriate SCSI support is enabled.
  80. A lot of drivers has their options described inside of
  81. Documentation/scsi/.
  82. SECURITY Different security models are enabled.
  83. SELINUX SELinux support is enabled.
  84. SERIAL Serial support is enabled.
  85. SH SuperH architecture is enabled.
  86. SMP The kernel is an SMP kernel.
  87. SPARC Sparc architecture is enabled.
  88. SWSUSP Software suspend (hibernation) is enabled.
  89. SUSPEND System suspend states are enabled.
  90. FTRACE Function tracing enabled.
  91. TS Appropriate touchscreen support is enabled.
  92. UMS USB Mass Storage support is enabled.
  93. USB USB support is enabled.
  94. USBHID USB Human Interface Device support is enabled.
  95. V4L Video For Linux support is enabled.
  96. VGA The VGA console has been enabled.
  97. VT Virtual terminal support is enabled.
  98. WDT Watchdog support is enabled.
  99. XT IBM PC/XT MFM hard disk support is enabled.
  100. X86-32 X86-32, aka i386 architecture is enabled.
  101. X86-64 X86-64 architecture is enabled.
  102. More X86-64 boot options can be found in
  103. Documentation/x86/x86_64/boot-options.txt .
  104. X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
  105. In addition, the following text indicates that the option:
  106. BUGS= Relates to possible processor bugs on the said processor.
  107. KNL Is a kernel start-up parameter.
  108. BOOT Is a boot loader parameter.
  109. Parameters denoted with BOOT are actually interpreted by the boot
  110. loader, and have no meaning to the kernel directly.
  111. Do not modify the syntax of boot loader parameters without extreme
  112. need or coordination with <Documentation/x86/boot.txt>.
  113. There are also arch-specific kernel-parameters not documented here.
  114. See for example <Documentation/x86/x86_64/boot-options.txt>.
  115. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  116. a trailing = on the name of any parameter states that that parameter will
  117. be entered as an environment variable, whereas its absence indicates that
  118. it will appear as a kernel argument readable via /proc/cmdline by programs
  119. running once the system is up.
  120. The number of kernel parameters is not limited, but the length of the
  121. complete command line (parameters including spaces etc.) is limited to
  122. a fixed number of characters. This limit depends on the architecture
  123. and is between 256 and 4096 characters. It is defined in the file
  124. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  125. acpi= [HW,ACPI,X86]
  126. Advanced Configuration and Power Interface
  127. Format: { force | off | ht | strict | noirq | rsdt }
  128. force -- enable ACPI if default was off
  129. off -- disable ACPI if default was on
  130. noirq -- do not use ACPI for IRQ routing
  131. ht -- run only enough ACPI to enable Hyper Threading
  132. strict -- Be less tolerant of platforms that are not
  133. strictly ACPI specification compliant.
  134. rsdt -- prefer RSDT over (default) XSDT
  135. See also Documentation/power/pm.txt, pci=noacpi
  136. acpi_apic_instance= [ACPI, IOAPIC]
  137. Format: <int>
  138. 2: use 2nd APIC table, if available
  139. 1,0: use 1st APIC table
  140. default: 0
  141. acpi_backlight= [HW,ACPI]
  142. acpi_backlight=vendor
  143. acpi_backlight=video
  144. If set to vendor, prefer vendor specific driver
  145. (e.g. thinkpad_acpi, sony_acpi, etc.) instead
  146. of the ACPI video.ko driver.
  147. acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
  148. acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
  149. Format: <int>
  150. CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
  151. debug output. Bits in debug_layer correspond to a
  152. _COMPONENT in an ACPI source file, e.g.,
  153. #define _COMPONENT ACPI_PCI_COMPONENT
  154. Bits in debug_level correspond to a level in
  155. ACPI_DEBUG_PRINT statements, e.g.,
  156. ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
  157. The debug_level mask defaults to "info". See
  158. Documentation/acpi/debug.txt for more information about
  159. debug layers and levels.
  160. Enable processor driver info messages:
  161. acpi.debug_layer=0x20000000
  162. Enable PCI/PCI interrupt routing info messages:
  163. acpi.debug_layer=0x400000
  164. Enable AML "Debug" output, i.e., stores to the Debug
  165. object while interpreting AML:
  166. acpi.debug_layer=0xffffffff acpi.debug_level=0x2
  167. Enable all messages related to ACPI hardware:
  168. acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
  169. Some values produce so much output that the system is
  170. unusable. The "log_buf_len" parameter may be useful
  171. if you need to capture more output.
  172. acpi_display_output= [HW,ACPI]
  173. acpi_display_output=vendor
  174. acpi_display_output=video
  175. See above.
  176. acpi_irq_balance [HW,ACPI]
  177. ACPI will balance active IRQs
  178. default in APIC mode
  179. acpi_irq_nobalance [HW,ACPI]
  180. ACPI will not move active IRQs (default)
  181. default in PIC mode
  182. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  183. Format: <irq>,<irq>...
  184. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  185. use by PCI
  186. Format: <irq>,<irq>...
  187. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  188. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  189. Format: To spoof as Windows 98: ="Microsoft Windows"
  190. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  191. acpi_osi="string1" # add string1 -- only one string
  192. acpi_osi="!string2" # remove built-in string2
  193. acpi_osi= # disable all strings
  194. acpi_pm_good [X86]
  195. Override the pmtimer bug detection: force the kernel
  196. to assume that this machine's pmtimer latches its value
  197. and always returns good values.
  198. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  199. Format: { level | edge | high | low }
  200. acpi_serialize [HW,ACPI] force serialization of AML methods
  201. acpi_skip_timer_override [HW,ACPI]
  202. Recognize and ignore IRQ0/pin2 Interrupt Override.
  203. For broken nForce2 BIOS resulting in XT-PIC timer.
  204. acpi_sleep= [HW,ACPI] Sleep options
  205. Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
  206. old_ordering, s4_nonvs }
  207. See Documentation/power/video.txt for information on
  208. s3_bios and s3_mode.
  209. s3_beep is for debugging; it makes the PC's speaker beep
  210. as soon as the kernel's real-mode entry point is called.
  211. s4_nohwsig prevents ACPI hardware signature from being
  212. used during resume from hibernation.
  213. old_ordering causes the ACPI 1.0 ordering of the _PTS
  214. control method, with respect to putting devices into
  215. low power states, to be enforced (the ACPI 2.0 ordering
  216. of _PTS is used by default).
  217. s4_nonvs prevents the kernel from saving/restoring the
  218. ACPI NVS memory during hibernation.
  219. acpi_use_timer_override [HW,ACPI]
  220. Use timer override. For some broken Nvidia NF5 boards
  221. that require a timer override, but don't have HPET
  222. acpi_enforce_resources= [ACPI]
  223. { strict | lax | no }
  224. Check for resource conflicts between native drivers
  225. and ACPI OperationRegions (SystemIO and SystemMemory
  226. only). IO ports and memory declared in ACPI might be
  227. used by the ACPI subsystem in arbitrary AML code and
  228. can interfere with legacy drivers.
  229. strict (default): access to resources claimed by ACPI
  230. is denied; legacy drivers trying to access reserved
  231. resources will fail to bind to device using them.
  232. lax: access to resources claimed by ACPI is allowed;
  233. legacy drivers trying to access reserved resources
  234. will bind successfully but a warning message is logged.
  235. no: ACPI OperationRegions are not marked as reserved,
  236. no further checks are performed.
  237. ad1848= [HW,OSS]
  238. Format: <io>,<irq>,<dma>,<dma2>,<type>
  239. add_efi_memmap [EFI; X86] Include EFI memory map in
  240. kernel's map of available physical RAM.
  241. advansys= [HW,SCSI]
  242. See header of drivers/scsi/advansys.c.
  243. advwdt= [HW,WDT] Advantech WDT
  244. Format: <iostart>,<iostop>
  245. aedsp16= [HW,OSS] Audio Excel DSP 16
  246. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  247. See also header of sound/oss/aedsp16.c.
  248. agp= [AGP]
  249. { off | try_unsupported }
  250. off: disable AGP support
  251. try_unsupported: try to drive unsupported chipsets
  252. (may crash computer or cause data corruption)
  253. aha152x= [HW,SCSI]
  254. See Documentation/scsi/aha152x.txt.
  255. aha1542= [HW,SCSI]
  256. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  257. aic7xxx= [HW,SCSI]
  258. See Documentation/scsi/aic7xxx.txt.
  259. aic79xx= [HW,SCSI]
  260. See Documentation/scsi/aic79xx.txt.
  261. amd_iommu= [HW,X86-84]
  262. Pass parameters to the AMD IOMMU driver in the system.
  263. Possible values are:
  264. isolate - enable device isolation (each device, as far
  265. as possible, will get its own protection
  266. domain) [default]
  267. share - put every device behind one IOMMU into the
  268. same protection domain
  269. fullflush - enable flushing of IO/TLB entries when
  270. they are unmapped. Otherwise they are
  271. flushed before they will be reused, which
  272. is a lot of faster
  273. amijoy.map= [HW,JOY] Amiga joystick support
  274. Map of devices attached to JOY0DAT and JOY1DAT
  275. Format: <a>,<b>
  276. See also Documentation/kernel/input/joystick.txt
  277. analog.map= [HW,JOY] Analog joystick and gamepad support
  278. Specifies type or capabilities of an analog joystick
  279. connected to one of 16 gameports
  280. Format: <type1>,<type2>,..<type16>
  281. apc= [HW,SPARC]
  282. Power management functions (SPARCstation-4/5 + deriv.)
  283. Format: noidle
  284. Disable APC CPU standby support. SPARCstation-Fox does
  285. not play well with APC CPU idle - disable it if you have
  286. APC and your system crashes randomly.
  287. apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
  288. Change the output verbosity whilst booting
  289. Format: { quiet (default) | verbose | debug }
  290. Change the amount of debugging information output
  291. when initialising the APIC and IO-APIC components.
  292. apm= [APM] Advanced Power Management
  293. See header of arch/x86/kernel/apm_32.c.
  294. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  295. Format: <io>,<irq>,<nodeID>
  296. ataflop= [HW,M68k]
  297. atarimouse= [HW,MOUSE] Atari Mouse
  298. atascsi= [HW,SCSI] Atari SCSI
  299. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  300. EzKey and similar keyboards
  301. atkbd.reset= [HW] Reset keyboard during initialization
  302. atkbd.set= [HW] Select keyboard code set
  303. Format: <int> (2 = AT (default), 3 = PS/2)
  304. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  305. keyboards
  306. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  307. Format: <bool> (0 = real, 1 = synthetic (default))
  308. atkbd.softrepeat= [HW]
  309. Use software keyboard repeat
  310. autotest [IA64]
  311. baycom_epp= [HW,AX25]
  312. Format: <io>,<mode>
  313. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  314. Format: <io>,<mode>
  315. See header of drivers/net/hamradio/baycom_par.c.
  316. baycom_ser_fdx= [HW,AX25]
  317. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  318. Format: <io>,<irq>,<mode>[,<baud>]
  319. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  320. baycom_ser_hdx= [HW,AX25]
  321. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  322. Format: <io>,<irq>,<mode>
  323. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  324. boot_delay= Milliseconds to delay each printk during boot.
  325. Values larger than 10 seconds (10000) are changed to
  326. no delay (0).
  327. Format: integer
  328. bootmem_debug [KNL] Enable bootmem allocator debug messages.
  329. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  330. bttv.radio= Most important insmod options are available as
  331. kernel args too.
  332. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  333. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  334. BusLogic= [HW,SCSI]
  335. See drivers/scsi/BusLogic.c, comment before function
  336. BusLogic_ParseDriverOptions().
  337. c101= [NET] Moxa C101 synchronous serial card
  338. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  339. Sometimes CPU hardware bugs make them report the cache
  340. size incorrectly. The kernel will attempt work arounds
  341. to fix known problems, but for some CPUs it is not
  342. possible to determine what the correct size should be.
  343. This option provides an override for these situations.
  344. capability.disable=
  345. [SECURITY] Disable capabilities. This would normally
  346. be used only if an alternative security model is to be
  347. configured. Potentially dangerous and should only be
  348. used if you are entirely sure of the consequences.
  349. ccw_timeout_log [S390]
  350. See Documentation/s390/CommonIO for details.
  351. cgroup_disable= [KNL] Disable a particular controller
  352. Format: {name of the controller(s) to disable}
  353. {Currently supported controllers - "memory"}
  354. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  355. Format: { "0" | "1" }
  356. See security/selinux/Kconfig help text.
  357. 0 -- check protection applied by kernel (includes
  358. any implied execute protection).
  359. 1 -- check protection requested by application.
  360. Default value is set via a kernel config option.
  361. Value can be changed at runtime via
  362. /selinux/checkreqprot.
  363. cio_ignore= [S390]
  364. See Documentation/s390/CommonIO for details.
  365. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  366. [Deprecated]
  367. Forces specified clocksource (if available) to be used
  368. when calculating gettimeofday(). If specified
  369. clocksource is not available, it defaults to PIT.
  370. Format: { pit | tsc | cyclone | pmtmr }
  371. clocksource= [GENERIC_TIME] Override the default clocksource
  372. Format: <string>
  373. Override the default clocksource and use the clocksource
  374. with the name specified.
  375. Some clocksource names to choose from, depending on
  376. the platform:
  377. [all] jiffies (this is the base, fallback clocksource)
  378. [ACPI] acpi_pm
  379. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  380. pxa_timer,timer3,32k_counter,timer0_1
  381. [AVR32] avr32
  382. [X86-32] pit,hpet,tsc,vmi-timer;
  383. scx200_hrt on Geode; cyclone on IBM x440
  384. [MIPS] MIPS
  385. [PARISC] cr16
  386. [S390] tod
  387. [SH] SuperH
  388. [SPARC64] tick
  389. [X86-64] hpet,tsc
  390. clearcpuid=BITNUM [X86]
  391. Disable CPUID feature X for the kernel. See
  392. arch/x86/include/asm/cpufeature.h for the valid bit
  393. numbers. Note the Linux specific bits are not necessarily
  394. stable over kernel options, but the vendor specific
  395. ones should be.
  396. Also note that user programs calling CPUID directly
  397. or using the feature without checking anything
  398. will still see it. This just prevents it from
  399. being used by the kernel or shown in /proc/cpuinfo.
  400. Also note the kernel might malfunction if you disable
  401. some critical bits.
  402. cmo_free_hint= [PPC] Format: { yes | no }
  403. Specify whether pages are marked as being inactive
  404. when they are freed. This is used in CMO environments
  405. to determine OS memory pressure for page stealing by
  406. a hypervisor.
  407. Default: yes
  408. code_bytes [X86] How many bytes of object code to print
  409. in an oops report.
  410. Range: 0 - 8192
  411. Default: 64
  412. com20020= [HW,NET] ARCnet - COM20020 chipset
  413. Format:
  414. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  415. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  416. Format: <io>[,<irq>]
  417. com90xx= [HW,NET]
  418. ARCnet - COM90xx chipset (memory-mapped buffers)
  419. Format: <io>[,<irq>[,<memstart>]]
  420. condev= [HW,S390] console device
  421. conmode=
  422. console= [KNL] Output console device and options.
  423. tty<n> Use the virtual console device <n>.
  424. ttyS<n>[,options]
  425. ttyUSB0[,options]
  426. Use the specified serial port. The options are of
  427. the form "bbbbpnf", where "bbbb" is the baud rate,
  428. "p" is parity ("n", "o", or "e"), "n" is number of
  429. bits, and "f" is flow control ("r" for RTS or
  430. omit it). Default is "9600n8".
  431. See Documentation/serial-console.txt for more
  432. information. See
  433. Documentation/networking/netconsole.txt for an
  434. alternative.
  435. uart[8250],io,<addr>[,options]
  436. uart[8250],mmio,<addr>[,options]
  437. Start an early, polled-mode console on the 8250/16550
  438. UART at the specified I/O port or MMIO address,
  439. switching to the matching ttyS device later. The
  440. options are the same as for ttyS, above.
  441. If the device connected to the port is not a TTY but a braille
  442. device, prepend "brl," before the device type, for instance
  443. console=brl,ttyS0
  444. For now, only VisioBraille is supported.
  445. consoleblank= [KNL] The console blank (screen saver) timeout in
  446. seconds. Defaults to 10*60 = 10mins. A value of 0
  447. disables the blank timer.
  448. coredump_filter=
  449. [KNL] Change the default value for
  450. /proc/<pid>/coredump_filter.
  451. See also Documentation/filesystems/proc.txt.
  452. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  453. Format:
  454. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  455. crashkernel=nn[KMG]@ss[KMG]
  456. [KNL] Reserve a chunk of physical memory to
  457. hold a kernel to switch to with kexec on panic.
  458. crashkernel=range1:size1[,range2:size2,...][@offset]
  459. [KNL] Same as above, but depends on the memory
  460. in the running system. The syntax of range is
  461. start-[end] where start and end are both
  462. a memory unit (amount[KMG]). See also
  463. Documentation/kdump/kdump.txt for a example.
  464. cs89x0_dma= [HW,NET]
  465. Format: <dma>
  466. cs89x0_media= [HW,NET]
  467. Format: { rj45 | aui | bnc }
  468. dasd= [HW,NET]
  469. See header of drivers/s390/block/dasd_devmap.c.
  470. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  471. (one device per port)
  472. Format: <port#>,<type>
  473. See also Documentation/input/joystick-parport.txt
  474. debug [KNL] Enable kernel debugging (events log level).
  475. debug_locks_verbose=
  476. [KNL] verbose self-tests
  477. Format=<0|1>
  478. Print debugging info while doing the locking API
  479. self-tests.
  480. We default to 0 (no extra messages), setting it to
  481. 1 will print _a lot_ more information - normally
  482. only useful to kernel developers.
  483. debug_objects [KNL] Enable object debugging
  484. no_debug_objects
  485. [KNL] Disable object debugging
  486. debugpat [X86] Enable PAT debugging
  487. decnet.addr= [HW,NET]
  488. Format: <area>[,<node>]
  489. See also Documentation/networking/decnet.txt.
  490. default_hugepagesz=
  491. [same as hugepagesz=] The size of the default
  492. HugeTLB page size. This is the size represented by
  493. the legacy /proc/ hugepages APIs, used for SHM, and
  494. default size when mounting hugetlbfs filesystems.
  495. Defaults to the default architecture's huge page size
  496. if not specified.
  497. dhash_entries= [KNL]
  498. Set number of hash buckets for dentry cache.
  499. digi= [HW,SERIAL]
  500. IO parameters + enable/disable command.
  501. digiepca= [HW,SERIAL]
  502. See drivers/char/README.epca and
  503. Documentation/serial/digiepca.txt.
  504. disable_mtrr_cleanup [X86]
  505. The kernel tries to adjust MTRR layout from continuous
  506. to discrete, to make X server driver able to add WB
  507. entry later. This parameter disables that.
  508. disable_mtrr_trim [X86, Intel and AMD only]
  509. By default the kernel will trim any uncacheable
  510. memory out of your available memory pool based on
  511. MTRR settings. This parameter disables that behavior,
  512. possibly causing your machine to run very slowly.
  513. disable_timer_pin_1 [X86]
  514. Disable PIN 1 of APIC timer
  515. Can be useful to work around chipset bugs.
  516. dmasound= [HW,OSS] Sound subsystem buffers
  517. dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
  518. this option disables the debugging code at boot.
  519. dma_debug_entries=<number>
  520. This option allows to tune the number of preallocated
  521. entries for DMA-API debugging code. One entry is
  522. required per DMA-API allocation. Use this if the
  523. DMA-API debugging code disables itself because the
  524. architectural default is too low.
  525. dma_debug_driver=<driver_name>
  526. With this option the DMA-API debugging driver
  527. filter feature can be enabled at boot time. Just
  528. pass the driver to filter for as the parameter.
  529. The filter can be disabled or changed to another
  530. driver later using sysfs.
  531. dscc4.setup= [NET]
  532. dtc3181e= [HW,SCSI]
  533. dynamic_printk Enables pr_debug()/dev_dbg() calls if
  534. CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
  535. These can also be switched on/off via
  536. <debugfs>/dynamic_printk/modules
  537. earlycon= [KNL] Output early console device and options.
  538. uart[8250],io,<addr>[,options]
  539. uart[8250],mmio,<addr>[,options]
  540. Start an early, polled-mode console on the 8250/16550
  541. UART at the specified I/O port or MMIO address.
  542. The options are the same as for ttyS, above.
  543. earlyprintk= [X86,SH,BLACKFIN]
  544. earlyprintk=vga
  545. earlyprintk=serial[,ttySn[,baudrate]]
  546. earlyprintk=dbgp
  547. Append ",keep" to not disable it when the real console
  548. takes over.
  549. Only vga or serial or usb debug port at a time.
  550. Currently only ttyS0 and ttyS1 are supported.
  551. Interaction with the standard serial driver is not
  552. very good.
  553. The VGA output is eventually overwritten by the real
  554. console.
  555. eata= [HW,SCSI]
  556. edd= [EDD]
  557. Format: {"off" | "on" | "skip[mbr]"}
  558. eisa_irq_edge= [PARISC,HW]
  559. See header of drivers/parisc/eisa.c.
  560. elanfreq= [X86-32]
  561. See comment before function elanfreq_setup() in
  562. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
  563. elevator= [IOSCHED]
  564. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  565. See Documentation/block/as-iosched.txt and
  566. Documentation/block/deadline-iosched.txt for details.
  567. elfcorehdr= [IA64,PPC,SH,X86]
  568. Specifies physical address of start of kernel core
  569. image elf header. Generally kexec loader will
  570. pass this option to capture kernel.
  571. See Documentation/kdump/kdump.txt for details.
  572. enable_mtrr_cleanup [X86]
  573. The kernel tries to adjust MTRR layout from continuous
  574. to discrete, to make X server driver able to add WB
  575. entry later. This parameter enables that.
  576. enable_timer_pin_1 [X86]
  577. Enable PIN 1 of APIC timer
  578. Can be useful to work around chipset bugs
  579. (in particular on some ATI chipsets).
  580. The kernel tries to set a reasonable default.
  581. enforcing [SELINUX] Set initial enforcing status.
  582. Format: {"0" | "1"}
  583. See security/selinux/Kconfig help text.
  584. 0 -- permissive (log only, no denials).
  585. 1 -- enforcing (deny and log).
  586. Default value is 0.
  587. Value can be changed at runtime via /selinux/enforce.
  588. ether= [HW,NET] Ethernet cards parameters
  589. This option is obsoleted by the "netdev=" option, which
  590. has equivalent usage. See its documentation for details.
  591. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  592. Format: <io>[,<irq>]
  593. failslab=
  594. fail_page_alloc=
  595. fail_make_request=[KNL]
  596. General fault injection mechanism.
  597. Format: <interval>,<probability>,<space>,<times>
  598. See also /Documentation/fault-injection/.
  599. fd_mcs= [HW,SCSI]
  600. See header of drivers/scsi/fd_mcs.c.
  601. fdomain= [HW,SCSI]
  602. See header of drivers/scsi/fdomain.c.
  603. floppy= [HW]
  604. See Documentation/blockdev/floppy.txt.
  605. force_pal_cache_flush
  606. [IA-64] Avoid check_sal_cache_flush which may hang on
  607. buggy SAL_CACHE_FLUSH implementations. Using this
  608. parameter will force ia64_sal_cache_flush to call
  609. ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
  610. ftrace=[tracer]
  611. [FTRACE] will set and start the specified tracer
  612. as early as possible in order to facilitate early
  613. boot debugging.
  614. ftrace_dump_on_oops
  615. [FTRACE] will dump the trace buffers on oops.
  616. ftrace_filter=[function-list]
  617. [FTRACE] Limit the functions traced by the function
  618. tracer at boot up. function-list is a comma separated
  619. list of functions. This list can be changed at run
  620. time by the set_ftrace_filter file in the debugfs
  621. tracing directory.
  622. ftrace_notrace=[function-list]
  623. [FTRACE] Do not trace the functions specified in
  624. function-list. This list can be changed at run time
  625. by the set_ftrace_notrace file in the debugfs
  626. tracing directory.
  627. gamecon.map[2|3]=
  628. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  629. support via parallel port (up to 5 devices per port)
  630. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  631. See also Documentation/input/joystick-parport.txt
  632. gamma= [HW,DRM]
  633. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  634. Format: off | on
  635. default: on
  636. gcov_persist= [GCOV] When non-zero (default), profiling data for
  637. kernel modules is saved and remains accessible via
  638. debugfs, even when the module is unloaded/reloaded.
  639. When zero, profiling data is discarded and associated
  640. debugfs files are removed at module unload time.
  641. gdth= [HW,SCSI]
  642. See header of drivers/scsi/gdth.c.
  643. gpt [EFI] Forces disk with valid GPT signature but
  644. invalid Protective MBR to be treated as GPT.
  645. gvp11= [HW,SCSI]
  646. hashdist= [KNL,NUMA] Large hashes allocated during boot
  647. are distributed across NUMA nodes. Defaults on
  648. for 64bit NUMA, off otherwise.
  649. Format: 0 | 1 (for off | on)
  650. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  651. hd= [EIDE] (E)IDE hard drive subsystem geometry
  652. Format: <cyl>,<head>,<sect>
  653. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  654. size of <nn>. This works even on boxes that have no
  655. highmem otherwise. This also works to reduce highmem
  656. size on bigger boxes.
  657. highres= [KNL] Enable/disable high resolution timer mode.
  658. Valid parameters: "on", "off"
  659. Default: "on"
  660. hisax= [HW,ISDN]
  661. See Documentation/isdn/README.HiSax.
  662. hlt [BUGS=ARM,SH]
  663. hpet= [X86-32,HPET] option to control HPET usage
  664. Format: { enable (default) | disable | force |
  665. verbose }
  666. disable: disable HPET and use PIT instead
  667. force: allow force enabled of undocumented chips (ICH4,
  668. VIA, nVidia)
  669. verbose: show contents of HPET registers during setup
  670. hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
  671. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
  672. On x86-64 and powerpc, this option can be specified
  673. multiple times interleaved with hugepages= to reserve
  674. huge pages of different sizes. Valid pages sizes on
  675. x86-64 are 2M (when the CPU supports "pse") and 1G
  676. (when the CPU supports the "pdpe1gb" cpuinfo flag)
  677. Note that 1GB pages can only be allocated at boot time
  678. using hugepages= and not freed afterwards.
  679. hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
  680. terminal devices. Valid values: 0..8
  681. hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
  682. If specified, z/VM IUCV HVC accepts connections
  683. from listed z/VM user IDs only.
  684. i2c_bus= [HW] Override the default board specific I2C bus speed
  685. or register an additional I2C bus that is not
  686. registered from board initialization code.
  687. Format:
  688. <bus_id>,<clkrate>
  689. i8042.debug [HW] Toggle i8042 debug mode
  690. i8042.direct [HW] Put keyboard port into non-translated mode
  691. i8042.dumbkbd [HW] Pretend that controller can only read data from
  692. keyboard and cannot control its state
  693. (Don't attempt to blink the leds)
  694. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  695. i8042.nokbd [HW] Don't check/create keyboard port
  696. i8042.noloop [HW] Disable the AUX Loopback command while probing
  697. for the AUX port
  698. i8042.nomux [HW] Don't check presence of an active multiplexing
  699. controller
  700. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  701. controllers
  702. i8042.panicblink=
  703. [HW] Frequency with which keyboard LEDs should blink
  704. when kernel panics (default is 0.5 sec)
  705. i8042.reset [HW] Reset the controller during init and cleanup
  706. i8042.unlock [HW] Unlock (ignore) the keylock
  707. i810= [HW,DRM]
  708. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  709. indicates that the driver is running on unsupported
  710. hardware.
  711. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  712. does not match list of supported models.
  713. i8k.power_status
  714. [HW] Report power status in /proc/i8k
  715. (disabled by default)
  716. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  717. capability is set.
  718. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  719. See Documentation/mca.txt.
  720. icn= [HW,ISDN]
  721. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  722. ide-core.nodma= [HW] (E)IDE subsystem
  723. Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
  724. .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
  725. .cdrom .chs .ignore_cable are additional options
  726. See Documentation/ide/ide.txt.
  727. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  728. Claim all unknown PCI IDE storage controllers.
  729. idle= [X86]
  730. Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
  731. Poll forces a polling idle loop that can slightly
  732. improve the performance of waking up a idle CPU, but
  733. will use a lot of power and make the system run hot.
  734. Not recommended.
  735. idle=mwait: On systems which support MONITOR/MWAIT but
  736. the kernel chose to not use it because it doesn't save
  737. as much power as a normal idle loop, use the
  738. MONITOR/MWAIT idle loop anyways. Performance should be
  739. the same as idle=poll.
  740. idle=halt: Halt is forced to be used for CPU idle.
  741. In such case C2/C3 won't be used again.
  742. idle=nomwait: Disable mwait for CPU C-states
  743. ignore_loglevel [KNL]
  744. Ignore loglevel setting - this will print /all/
  745. kernel messages to the console. Useful for debugging.
  746. ihash_entries= [KNL]
  747. Set number of hash buckets for inode cache.
  748. ima_audit= [IMA]
  749. Format: { "0" | "1" }
  750. 0 -- integrity auditing messages. (Default)
  751. 1 -- enable informational integrity auditing messages.
  752. ima_hash= [IMA]
  753. Formt: { "sha1" | "md5" }
  754. default: "sha1"
  755. ima_tcb [IMA]
  756. Load a policy which meets the needs of the Trusted
  757. Computing Base. This means IMA will measure all
  758. programs exec'd, files mmap'd for exec, and all files
  759. opened for read by uid=0.
  760. in2000= [HW,SCSI]
  761. See header of drivers/scsi/in2000.c.
  762. init= [KNL]
  763. Format: <full_path>
  764. Run specified binary instead of /sbin/init as init
  765. process.
  766. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  767. for working out where the kernel is dying during
  768. startup.
  769. initrd= [BOOT] Specify the location of the initial ramdisk
  770. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  771. Format: <irq>
  772. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  773. on
  774. Enable intel iommu driver.
  775. off
  776. Disable intel iommu driver.
  777. igfx_off [Default Off]
  778. By default, gfx is mapped as normal device. If a gfx
  779. device has a dedicated DMAR unit, the DMAR unit is
  780. bypassed by not enabling DMAR with this option. In
  781. this case, gfx device will use physical address for
  782. DMA.
  783. forcedac [x86_64]
  784. With this option iommu will not optimize to look
  785. for io virtual address below 32 bit forcing dual
  786. address cycle on pci bus for cards supporting greater
  787. than 32 bit addressing. The default is to look
  788. for translation below 32 bit and if not available
  789. then look in the higher range.
  790. strict [Default Off]
  791. With this option on every unmap_single operation will
  792. result in a hardware IOTLB flush operation as opposed
  793. to batching them for performance.
  794. inttest= [IA64]
  795. iomem= Disable strict checking of access to MMIO memory
  796. strict regions from userspace.
  797. relaxed
  798. iommu= [x86]
  799. off
  800. force
  801. noforce
  802. biomerge
  803. panic
  804. nopanic
  805. merge
  806. nomerge
  807. forcesac
  808. soft
  809. pt [x86, IA64]
  810. io7= [HW] IO7 for Marvel based alpha systems
  811. See comment before marvel_specify_io7 in
  812. arch/alpha/kernel/core_marvel.c.
  813. io_delay= [X86] I/O delay method
  814. 0x80
  815. Standard port 0x80 based delay
  816. 0xed
  817. Alternate port 0xed based delay (needed on some systems)
  818. udelay
  819. Simple two microseconds delay
  820. none
  821. No delay
  822. ip= [IP_PNP]
  823. See Documentation/filesystems/nfsroot.txt.
  824. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  825. See comment before ip2_setup() in
  826. drivers/char/ip2/ip2base.c.
  827. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  828. See header of drivers/scsi/ips.c.
  829. irqfixup [HW]
  830. When an interrupt is not handled search all handlers
  831. for it. Intended to get systems with badly broken
  832. firmware running.
  833. irqpoll [HW]
  834. When an interrupt is not handled search all handlers
  835. for it. Also check all handlers each timer
  836. interrupt. Intended to get systems with badly broken
  837. firmware running.
  838. isapnp= [ISAPNP]
  839. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  840. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  841. Format:
  842. <cpu number>,...,<cpu number>
  843. or
  844. <cpu number>-<cpu number>
  845. (must be a positive range in ascending order)
  846. or a mixture
  847. <cpu number>,...,<cpu number>-<cpu number>
  848. This option can be used to specify one or more CPUs
  849. to isolate from the general SMP balancing and scheduling
  850. algorithms. You can move a process onto or off an
  851. "isolated" CPU via the CPU affinity syscalls or cpuset.
  852. <cpu number> begins at 0 and the maximum value is
  853. "number of CPUs in system - 1".
  854. This option is the preferred way to isolate CPUs. The
  855. alternative -- manually setting the CPU mask of all
  856. tasks in the system -- can cause problems and
  857. suboptimal load balancer performance.
  858. iucv= [HW,NET]
  859. js= [HW,JOY] Analog joystick
  860. See Documentation/input/joystick.txt.
  861. keepinitrd [HW,ARM]
  862. kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  863. specifies the amount of memory usable by the kernel
  864. for non-movable allocations. The requested amount is
  865. spread evenly throughout all nodes in the system. The
  866. remaining memory in each node is used for Movable
  867. pages. In the event, a node is too small to have both
  868. kernelcore and Movable pages, kernelcore pages will
  869. take priority and other nodes will have a larger number
  870. of kernelcore pages. The Movable zone is used for the
  871. allocation of pages that may be reclaimed or moved
  872. by the page migration subsystem. This means that
  873. HugeTLB pages may not be allocated from this zone.
  874. Note that allocations like PTEs-from-HighMem still
  875. use the HighMem zone if it exists, and the Normal
  876. zone if it does not.
  877. kgdboc= [HW] kgdb over consoles.
  878. Requires a tty driver that supports console polling.
  879. (only serial supported for now)
  880. Format: <serial_device>[,baud]
  881. kmac= [MIPS] korina ethernet MAC address.
  882. Configure the RouterBoard 532 series on-chip
  883. Ethernet adapter MAC address.
  884. kmemleak= [KNL] Boot-time kmemleak enable/disable
  885. Valid arguments: on, off
  886. Default: on
  887. kstack=N [X86] Print N words from the kernel stack
  888. in oops dumps.
  889. l2cr= [PPC]
  890. l3cr= [PPC]
  891. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  892. disabled it.
  893. lapic_timer_c2_ok [X86,APIC] trust the local apic timer
  894. in C2 power state.
  895. libata.dma= [LIBATA] DMA control
  896. libata.dma=0 Disable all PATA and SATA DMA
  897. libata.dma=1 PATA and SATA Disk DMA only
  898. libata.dma=2 ATAPI (CDROM) DMA only
  899. libata.dma=4 Compact Flash DMA only
  900. Combinations also work, so libata.dma=3 enables DMA
  901. for disks and CDROMs, but not CFs.
  902. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  903. when set.
  904. Format: <int>
  905. libata.force= [LIBATA] Force configurations. The format is comma
  906. separated list of "[ID:]VAL" where ID is
  907. PORT[:DEVICE]. PORT and DEVICE are decimal numbers
  908. matching port, link or device. Basically, it matches
  909. the ATA ID string printed on console by libata. If
  910. the whole ID part is omitted, the last PORT and DEVICE
  911. values are used. If ID hasn't been specified yet, the
  912. configuration applies to all ports, links and devices.
  913. If only DEVICE is omitted, the parameter applies to
  914. the port and all links and devices behind it. DEVICE
  915. number of 0 either selects the first device or the
  916. first fan-out link behind PMP device. It does not
  917. select the host link. DEVICE number of 15 selects the
  918. host link and device attached to it.
  919. The VAL specifies the configuration to force. As long
  920. as there's no ambiguity shortcut notation is allowed.
  921. For example, both 1.5 and 1.5G would work for 1.5Gbps.
  922. The following configurations can be forced.
  923. * Cable type: 40c, 80c, short40c, unk, ign or sata.
  924. Any ID with matching PORT is used.
  925. * SATA link speed limit: 1.5Gbps or 3.0Gbps.
  926. * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
  927. udma[/][16,25,33,44,66,100,133] notation is also
  928. allowed.
  929. * [no]ncq: Turn on or off NCQ.
  930. * nohrst, nosrst, norst: suppress hard, soft
  931. and both resets.
  932. If there are multiple matching configurations changing
  933. the same attribute, the last one is used.
  934. lmb=debug [KNL] Enable lmb debug messages.
  935. load_ramdisk= [RAM] List of ramdisks to load from floppy
  936. See Documentation/blockdev/ramdisk.txt.
  937. lockd.nlm_grace_period=P [NFS] Assign grace period.
  938. Format: <integer>
  939. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  940. Format: <integer>
  941. lockd.nlm_timeout=T [NFS] Assign timeout value.
  942. Format: <integer>
  943. lockd.nlm_udpport=M [NFS] Assign UDP port.
  944. Format: <integer>
  945. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  946. Format: <irq>
  947. loglevel= All Kernel Messages with a loglevel smaller than the
  948. console loglevel will be printed to the console. It can
  949. also be changed with klogd or other programs. The
  950. loglevels are defined as follows:
  951. 0 (KERN_EMERG) system is unusable
  952. 1 (KERN_ALERT) action must be taken immediately
  953. 2 (KERN_CRIT) critical conditions
  954. 3 (KERN_ERR) error conditions
  955. 4 (KERN_WARNING) warning conditions
  956. 5 (KERN_NOTICE) normal but significant condition
  957. 6 (KERN_INFO) informational
  958. 7 (KERN_DEBUG) debug-level messages
  959. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  960. Format: { n | nk | nM }
  961. n must be a power of two. The default size
  962. is set in the kernel config file.
  963. logo.nologo [FB] Disables display of the built-in Linux logo.
  964. This may be used to provide more screen space for
  965. kernel log messages and is useful when debugging
  966. kernel boot problems.
  967. lp=0 [LP] Specify parallel ports to use, e.g,
  968. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  969. lp=reset first parallel port). 'lp=0' disables the
  970. lp=auto printer driver. 'lp=reset' (which can be
  971. specified in addition to the ports) causes
  972. attached printers to be reset. Using
  973. lp=port1,port2,... specifies the parallel ports
  974. to associate lp devices with, starting with
  975. lp0. A port specification may be 'none' to skip
  976. that lp device, or a parport name such as
  977. 'parport0'. Specifying 'lp=auto' instead of a
  978. port specification list means that device IDs
  979. from each port should be examined, to see if
  980. an IEEE 1284-compliant printer is attached; if
  981. so, the driver will manage that printer.
  982. See also header of drivers/char/lp.c.
  983. lpj=n [KNL]
  984. Sets loops_per_jiffy to given constant, thus avoiding
  985. time-consuming boot-time autodetection (up to 250 ms per
  986. CPU). 0 enables autodetection (default). To determine
  987. the correct value for your kernel, boot with normal
  988. autodetection and see what value is printed. Note that
  989. on SMP systems the preset will be applied to all CPUs,
  990. which is likely to cause problems if your CPUs need
  991. significantly divergent settings. An incorrect value
  992. will cause delays in the kernel to be wrong, leading to
  993. unpredictable I/O errors and other breakage. Although
  994. unlikely, in the extreme case this might damage your
  995. hardware.
  996. ltpc= [NET]
  997. Format: <io>,<irq>,<dma>
  998. mac5380= [HW,SCSI] Format:
  999. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  1000. machvec= [IA64] Force the use of a particular machine-vector
  1001. (machvec) in a generic kernel.
  1002. Example: machvec=hpzx1_swiotlb
  1003. max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
  1004. than or equal to this physical address is ignored.
  1005. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  1006. should make use of. maxcpus=n : n >= 0 limits the
  1007. kernel to using 'n' processors. n=0 is a special case,
  1008. it is equivalent to "nosmp", which also disables
  1009. the IO APIC.
  1010. max_loop= [LOOP] Maximum number of loopback devices that can
  1011. be mounted
  1012. Format: <1-256>
  1013. max_luns= [SCSI] Maximum number of LUNs to probe.
  1014. Should be between 1 and 2^32-1.
  1015. max_report_luns=
  1016. [SCSI] Maximum number of LUNs received.
  1017. Should be between 1 and 16384.
  1018. mcatest= [IA-64]
  1019. mce [X86-32] Machine Check Exception
  1020. mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
  1021. md= [HW] RAID subsystems devices and level
  1022. See Documentation/md.txt.
  1023. mdacon= [MDA]
  1024. Format: <first>,<last>
  1025. Specifies range of consoles to be captured by the MDA.
  1026. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  1027. Amount of memory to be used when the kernel is not able
  1028. to see the whole system memory or for test.
  1029. [X86-32] Use together with memmap= to avoid physical
  1030. address space collisions. Without memmap= PCI devices
  1031. could be placed at addresses belonging to unused RAM.
  1032. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  1033. memory.
  1034. memchunk=nn[KMG]
  1035. [KNL,SH] Allow user to override the default size for
  1036. per-device physically contiguous DMA buffers.
  1037. memmap=exactmap [KNL,X86] Enable setting of an exact
  1038. E820 memory map, as specified by the user.
  1039. Such memmap=exactmap lines can be constructed based on
  1040. BIOS output or other requirements. See the memmap=nn@ss
  1041. option description.
  1042. memmap=nn[KMG]@ss[KMG]
  1043. [KNL] Force usage of a specific region of memory
  1044. Region of memory to be used, from ss to ss+nn.
  1045. memmap=nn[KMG]#ss[KMG]
  1046. [KNL,ACPI] Mark specific memory as ACPI data.
  1047. Region of memory to be used, from ss to ss+nn.
  1048. memmap=nn[KMG]$ss[KMG]
  1049. [KNL,ACPI] Mark specific memory as reserved.
  1050. Region of memory to be used, from ss to ss+nn.
  1051. Example: Exclude memory from 0x18690000-0x1869ffff
  1052. memmap=64K$0x18690000
  1053. or
  1054. memmap=0x10000$0x18690000
  1055. memory_corruption_check=0/1 [X86]
  1056. Some BIOSes seem to corrupt the first 64k of
  1057. memory when doing things like suspend/resume.
  1058. Setting this option will scan the memory
  1059. looking for corruption. Enabling this will
  1060. both detect corruption and prevent the kernel
  1061. from using the memory being corrupted.
  1062. However, its intended as a diagnostic tool; if
  1063. repeatable BIOS-originated corruption always
  1064. affects the same memory, you can use memmap=
  1065. to prevent the kernel from using that memory.
  1066. memory_corruption_check_size=size [X86]
  1067. By default it checks for corruption in the low
  1068. 64k, making this memory unavailable for normal
  1069. use. Use this parameter to scan for
  1070. corruption in more or less memory.
  1071. memory_corruption_check_period=seconds [X86]
  1072. By default it checks for corruption every 60
  1073. seconds. Use this parameter to check at some
  1074. other rate. 0 disables periodic checking.
  1075. memtest= [KNL,X86] Enable memtest
  1076. Format: <integer>
  1077. default : 0 <disable>
  1078. Specifies the number of memtest passes to be
  1079. performed. Each pass selects another test
  1080. pattern from a given set of patterns. Memtest
  1081. fills the memory with this pattern, validates
  1082. memory contents and reserves bad memory
  1083. regions that are detected.
  1084. meye.*= [HW] Set MotionEye Camera parameters
  1085. See Documentation/video4linux/meye.txt.
  1086. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  1087. Multi-Function General Purpose Timers on AMD Geode
  1088. platforms.
  1089. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  1090. the BIOS has incorrectly applied a workaround. TinyBIOS
  1091. version 0.98 is known to be affected, 0.99 fixes the
  1092. problem by letting the user disable the workaround.
  1093. mga= [HW,DRM]
  1094. min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
  1095. physical address is ignored.
  1096. mini2440= [ARM,HW,KNL]
  1097. Format:[0..2][b][c][t]
  1098. Default: "0tb"
  1099. MINI2440 configuration specification:
  1100. 0 - The attached screen is the 3.5" TFT
  1101. 1 - The attached screen is the 7" TFT
  1102. 2 - The VGA Shield is attached (1024x768)
  1103. Leaving out the screen size parameter will not load
  1104. the TFT driver, and the framebuffer will be left
  1105. unconfigured.
  1106. b - Enable backlight. The TFT backlight pin will be
  1107. linked to the kernel VESA blanking code and a GPIO
  1108. LED. This parameter is not necessary when using the
  1109. VGA shield.
  1110. c - Enable the s3c camera interface.
  1111. t - Reserved for enabling touchscreen support. The
  1112. touchscreen support is not enabled in the mainstream
  1113. kernel as of 2.6.30, a preliminary port can be found
  1114. in the "bleeding edge" mini2440 support kernel at
  1115. http://repo.or.cz/w/linux-2.6/mini2440.git
  1116. mminit_loglevel=
  1117. [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
  1118. parameter allows control of the logging verbosity for
  1119. the additional memory initialisation checks. A value
  1120. of 0 disables mminit logging and a level of 4 will
  1121. log everything. Information is printed at KERN_DEBUG
  1122. so loglevel=8 may also need to be specified.
  1123. mousedev.tap_time=
  1124. [MOUSE] Maximum time between finger touching and
  1125. leaving touchpad surface for touch to be considered
  1126. a tap and be reported as a left button click (for
  1127. touchpads working in absolute mode only).
  1128. Format: <msecs>
  1129. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  1130. reporting absolute coordinates, such as tablets
  1131. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  1132. reporting absolute coordinates, such as tablets
  1133. movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  1134. is similar to kernelcore except it specifies the
  1135. amount of memory used for migratable allocations.
  1136. If both kernelcore and movablecore is specified,
  1137. then kernelcore will be at *least* the specified
  1138. value but may be more. If movablecore on its own
  1139. is specified, the administrator must be careful
  1140. that the amount of memory usable for all allocations
  1141. is not too small.
  1142. mpu401= [HW,OSS]
  1143. Format: <io>,<irq>
  1144. MTD_Partition= [MTD]
  1145. Format: <name>,<region-number>,<size>,<offset>
  1146. MTD_Region= [MTD] Format:
  1147. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  1148. mtdparts= [MTD]
  1149. See drivers/mtd/cmdlinepart.c.
  1150. onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
  1151. Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
  1152. boundary - index of last SLC block on Flex-OneNAND.
  1153. The remaining blocks are configured as MLC blocks.
  1154. lock - Configure if Flex-OneNAND boundary should be locked.
  1155. Once locked, the boundary cannot be changed.
  1156. 1 indicates lock status, 0 indicates unlock status.
  1157. mtdset= [ARM]
  1158. ARM/S3C2412 JIVE boot control
  1159. See arch/arm/mach-s3c2412/mach-jive.c
  1160. mtouchusb.raw_coordinates=
  1161. [HW] Make the MicroTouch USB driver use raw coordinates
  1162. ('y', default) or cooked coordinates ('n')
  1163. mtrr_chunk_size=nn[KMG] [X86]
  1164. used for mtrr cleanup. It is largest continuous chunk
  1165. that could hold holes aka. UC entries.
  1166. mtrr_gran_size=nn[KMG] [X86]
  1167. Used for mtrr cleanup. It is granularity of mtrr block.
  1168. Default is 1.
  1169. Large value could prevent small alignment from
  1170. using up MTRRs.
  1171. mtrr_spare_reg_nr=n [X86]
  1172. Format: <integer>
  1173. Range: 0,7 : spare reg number
  1174. Default : 1
  1175. Used for mtrr cleanup. It is spare mtrr entries number.
  1176. Set to 2 or more if your graphical card needs more.
  1177. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  1178. NCR_D700= [HW,SCSI]
  1179. See header of drivers/scsi/NCR_D700.c.
  1180. ncr5380= [HW,SCSI]
  1181. ncr53c400= [HW,SCSI]
  1182. ncr53c400a= [HW,SCSI]
  1183. ncr53c406a= [HW,SCSI]
  1184. ncr53c8xx= [HW,SCSI]
  1185. netdev= [NET] Network devices parameters
  1186. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  1187. Note that mem_start is often overloaded to mean
  1188. something different and driver-specific.
  1189. This usage is only documented in each driver source
  1190. file if at all.
  1191. nf_conntrack.acct=
  1192. [NETFILTER] Enable connection tracking flow accounting
  1193. 0 to disable accounting
  1194. 1 to enable accounting
  1195. Default value depends on CONFIG_NF_CT_ACCT that is
  1196. going to be removed in 2.6.29.
  1197. nfsaddrs= [NFS]
  1198. See Documentation/filesystems/nfsroot.txt.
  1199. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  1200. See Documentation/filesystems/nfsroot.txt.
  1201. nfs.callback_tcpport=
  1202. [NFS] set the TCP port on which the NFSv4 callback
  1203. channel should listen.
  1204. nfs.idmap_cache_timeout=
  1205. [NFS] set the maximum lifetime for idmapper cache
  1206. entries.
  1207. nfs.enable_ino64=
  1208. [NFS] enable 64-bit inode numbers.
  1209. If zero, the NFS client will fake up a 32-bit inode
  1210. number for the readdir() and stat() syscalls instead
  1211. of returning the full 64-bit number.
  1212. The default is to return 64-bit inode numbers.
  1213. nmi_debug= [KNL,AVR32] Specify one or more actions to take
  1214. when a NMI is triggered.
  1215. Format: [state][,regs][,debounce][,die]
  1216. nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
  1217. Format: [panic,][num]
  1218. Valid num: 0,1,2
  1219. 0 - turn nmi_watchdog off
  1220. 1 - use the IO-APIC timer for the NMI watchdog
  1221. 2 - use the local APIC for the NMI watchdog using
  1222. a performance counter. Note: This will use one
  1223. performance counter and the local APIC's performance
  1224. vector.
  1225. When panic is specified, panic when an NMI watchdog
  1226. timeout occurs.
  1227. This is useful when you use a panic=... timeout and
  1228. need the box quickly up again.
  1229. Instead of 1 and 2 it is possible to use the following
  1230. symbolic names: lapic and ioapic
  1231. Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
  1232. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  1233. emulation library even if a 387 maths coprocessor
  1234. is present.
  1235. no_console_suspend
  1236. [HW] Never suspend the console
  1237. Disable suspending of consoles during suspend and
  1238. hibernate operations. Once disabled, debugging
  1239. messages can reach various consoles while the rest
  1240. of the system is being put to sleep (ie, while
  1241. debugging driver suspend/resume hooks). This may
  1242. not work reliably with all consoles, but is known
  1243. to work with serial and VGA consoles.
  1244. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  1245. caches in the slab allocator. Saves per-node memory,
  1246. but will impact performance.
  1247. noalign [KNL,ARM]
  1248. noapic [SMP,APIC] Tells the kernel to not make use of any
  1249. IOAPICs that may be present in the system.
  1250. nobats [PPC] Do not use BATs for mapping kernel lowmem
  1251. on "Classic" PPC cores.
  1252. nocache [ARM]
  1253. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  1254. nodelayacct [KNL] Disable per-task delay accounting
  1255. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  1256. nodsp [SH] Disable hardware DSP at boot time.
  1257. noefi [X86] Disable EFI runtime services support.
  1258. noexec [IA-64]
  1259. noexec [X86]
  1260. On X86-32 available only on PAE configured kernels.
  1261. noexec=on: enable non-executable mappings (default)
  1262. noexec=off: disable non-executable mappings
  1263. noexec32 [X86-64]
  1264. This affects only 32-bit executables.
  1265. noexec32=on: enable non-executable mappings (default)
  1266. read doesn't imply executable mappings
  1267. noexec32=off: disable non-executable mappings
  1268. read implies executable mappings
  1269. nofpu [SH] Disable hardware FPU at boot time.
  1270. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  1271. register save and restore. The kernel will only save
  1272. legacy floating-point registers on task switch.
  1273. noxsave [BUGS=X86] Disables x86 extended register state save
  1274. and restore using xsave. The kernel will fallback to
  1275. enabling legacy floating-point and sse state.
  1276. nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
  1277. wfi(ARM) instruction doesn't work correctly and not to
  1278. use it. This is also useful when using JTAG debugger.
  1279. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  1280. instruction doesn't work correctly and not to
  1281. use it.
  1282. no_file_caps Tells the kernel not to honor file capabilities. The
  1283. only way then for a file to be executed with privilege
  1284. is to be setuid root or executed by root.
  1285. nohalt [IA-64] Tells the kernel not to use the power saving
  1286. function PAL_HALT_LIGHT when idle. This increases
  1287. power-consumption. On the positive side, it reduces
  1288. interrupt wake-up latency, which may improve performance
  1289. in certain environments such as networked servers or
  1290. real-time systems.
  1291. nohz= [KNL] Boottime enable/disable dynamic ticks
  1292. Valid arguments: on, off
  1293. Default: on
  1294. noiotrap [SH] Disables trapped I/O port accesses.
  1295. noirqdebug [X86-32] Disables the code which attempts to detect and
  1296. disable unhandled interrupt sources.
  1297. no_timer_check [X86,APIC] Disables the code which tests for
  1298. broken timer IRQ sources.
  1299. noisapnp [ISAPNP] Disables ISA PnP code.
  1300. noinitrd [RAM] Tells the kernel not to load any configured
  1301. initial RAM disk.
  1302. nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
  1303. remapping.
  1304. nointroute [IA-64]
  1305. nojitter [IA64] Disables jitter checking for ITC timers.
  1306. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  1307. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  1308. noltlbs [PPC] Do not use large page/tlb entries for kernel
  1309. lowmem mapping on PPC40x.
  1310. nomca [IA-64] Disable machine check abort handling
  1311. nomce [X86-32] Machine Check Exception
  1312. nomfgpt [X86-32] Disable Multi-Function General Purpose
  1313. Timer usage (for AMD Geode machines).
  1314. norandmaps Don't use address space randomization. Equivalent to
  1315. echo 0 > /proc/sys/kernel/randomize_va_space
  1316. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  1317. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1318. with UP alternatives
  1319. noresidual [PPC] Don't use residual data on PReP machines.
  1320. noresume [SWSUSP] Disables resume and restores original swap
  1321. space.
  1322. no-scroll [VGA] Disables scrollback.
  1323. This is required for the Braillex ib80-piezo Braille
  1324. reader made by F.H. Papenmeier (Germany).
  1325. nosbagart [IA-64]
  1326. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1327. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1328. and disable the IO APIC. legacy for "maxcpus=0".
  1329. nosoftlockup [KNL] Disable the soft-lockup detector.
  1330. noswapaccount [KNL] Disable accounting of swap in memory resource
  1331. controller. (See Documentation/cgroups/memory.txt)
  1332. nosync [HW,M68K] Disables sync negotiation for all devices.
  1333. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1334. nousb [USB] Disable the USB subsystem
  1335. nowb [ARM]
  1336. nox2apic [X86-64,APIC] Do not enable x2APIC mode.
  1337. nptcg= [IA64] Override max number of concurrent global TLB
  1338. purges which is reported from either PAL_VM_SUMMARY or
  1339. SAL PALO.
  1340. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1341. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1342. one of ['zone', 'node', 'default'] can be specified
  1343. This can be set from sysctl after boot.
  1344. See Documentation/sysctl/vm.txt for details.
  1345. ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
  1346. See Documentation/debugging-via-ohci1394.txt for more
  1347. info.
  1348. olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
  1349. Rather than timing out after 20 ms if an EC
  1350. command is not properly ACKed, override the length
  1351. of the timeout. We have interrupts disabled while
  1352. waiting for the ACK, so if this is set too high
  1353. interrupts *may* be lost!
  1354. opl3= [HW,OSS]
  1355. Format: <io>
  1356. oprofile.timer= [HW]
  1357. Use timer interrupt instead of performance counters
  1358. oprofile.cpu_type= Force an oprofile cpu type
  1359. This might be useful if you have an older oprofile
  1360. userland or if you want common events.
  1361. Format: { arch_perfmon }
  1362. arch_perfmon: [X86] Force use of architectural
  1363. perfmon on Intel CPUs instead of the
  1364. CPU specific event set.
  1365. osst= [HW,SCSI] SCSI Tape Driver
  1366. Format: <buffer_size>,<write_threshold>
  1367. See also Documentation/scsi/st.txt.
  1368. panic= [KNL] Kernel behaviour on panic
  1369. Format: <timeout>
  1370. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1371. connected to, default is 0.
  1372. Format: <parport#>
  1373. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1374. 0 for XT, 1 for AT (default is AT).
  1375. Format: <mode>
  1376. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1377. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1378. Use 'auto' to force the driver to use any
  1379. IRQ/DMA settings detected (the default is to
  1380. ignore detected IRQ/DMA settings because of
  1381. possible conflicts). You can specify the base
  1382. address, IRQ, and DMA settings; IRQ and DMA
  1383. should be numbers, or 'auto' (for using detected
  1384. settings on that particular port), or 'nofifo'
  1385. (to avoid using a FIFO even if it is detected).
  1386. Parallel ports are assigned in the order they
  1387. are specified on the command line, starting
  1388. with parport0.
  1389. parport_init_mode= [HW,PPT]
  1390. Configure VIA parallel port to operate in
  1391. a specific mode. This is necessary on Pegasos
  1392. computer where firmware has no options for setting
  1393. up parallel port mode and sets it to spp.
  1394. Currently this function knows 686a and 8231 chips.
  1395. Format: [spp|ps2|epp|ecp|ecpepp]
  1396. pas2= [HW,OSS] Format:
  1397. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1398. pas16= [HW,SCSI]
  1399. See header of drivers/scsi/pas16.c.
  1400. pause_on_oops=
  1401. Halt all CPUs after the first oops has been printed for
  1402. the specified number of seconds. This is to be used if
  1403. your oopses keep scrolling off the screen.
  1404. pcbit= [HW,ISDN]
  1405. pcd. [PARIDE]
  1406. See header of drivers/block/paride/pcd.c.
  1407. See also Documentation/blockdev/paride.txt.
  1408. pci=option[,option...] [PCI] various PCI subsystem options:
  1409. earlydump [X86] dump PCI config space before the kernel
  1410. changes anything
  1411. off [X86] don't probe for the PCI bus
  1412. bios [X86-32] force use of PCI BIOS, don't access
  1413. the hardware directly. Use this if your machine
  1414. has a non-standard PCI host bridge.
  1415. nobios [X86-32] disallow use of PCI BIOS, only direct
  1416. hardware access methods are allowed. Use this
  1417. if you experience crashes upon bootup and you
  1418. suspect they are caused by the BIOS.
  1419. conf1 [X86] Force use of PCI Configuration
  1420. Mechanism 1.
  1421. conf2 [X86] Force use of PCI Configuration
  1422. Mechanism 2.
  1423. noaer [PCIE] If the PCIEAER kernel config parameter is
  1424. enabled, this kernel boot option can be used to
  1425. disable the use of PCIE advanced error reporting.
  1426. nodomains [PCI] Disable support for multiple PCI
  1427. root domains (aka PCI segments, in ACPI-speak).
  1428. nommconf [X86] Disable use of MMCONFIG for PCI
  1429. Configuration
  1430. check_enable_amd_mmconf [X86] check for and enable
  1431. properly configured MMIO access to PCI
  1432. config space on AMD family 10h CPU
  1433. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1434. enabled, this kernel boot option can be used to
  1435. disable the use of MSI interrupts system-wide.
  1436. noioapicquirk [APIC] Disable all boot interrupt quirks.
  1437. Safety option to keep boot IRQs enabled. This
  1438. should never be necessary.
  1439. ioapicreroute [APIC] Enable rerouting of boot IRQs to the
  1440. primary IO-APIC for bridges that cannot disable
  1441. boot IRQs. This fixes a source of spurious IRQs
  1442. when the system masks IRQs.
  1443. noioapicreroute [APIC] Disable workaround that uses the
  1444. boot IRQ equivalent of an IRQ that connects to
  1445. a chipset where boot IRQs cannot be disabled.
  1446. The opposite of ioapicreroute.
  1447. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1448. routing table. These calls are known to be buggy
  1449. on several machines and they hang the machine
  1450. when used, but on other computers it's the only
  1451. way to get the interrupt routing table. Try
  1452. this option if the kernel is unable to allocate
  1453. IRQs or discover secondary PCI buses on your
  1454. motherboard.
  1455. rom [X86] Assign address space to expansion ROMs.
  1456. Use with caution as certain devices share
  1457. address decoders between ROMs and other
  1458. resources.
  1459. norom [X86] Do not assign address space to
  1460. expansion ROMs that do not already have
  1461. BIOS assigned address ranges.
  1462. irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
  1463. assigned automatically to PCI devices. You can
  1464. make the kernel exclude IRQs of your ISA cards
  1465. this way.
  1466. pirqaddr=0xAAAAA [X86] Specify the physical address
  1467. of the PIRQ table (normally generated
  1468. by the BIOS) if it is outside the
  1469. F0000h-100000h range.
  1470. lastbus=N [X86] Scan all buses thru bus #N. Can be
  1471. useful if the kernel is unable to find your
  1472. secondary buses and you want to tell it
  1473. explicitly which ones they are.
  1474. assign-busses [X86] Always assign all PCI bus
  1475. numbers ourselves, overriding
  1476. whatever the firmware may have done.
  1477. usepirqmask [X86] Honor the possible IRQ mask stored
  1478. in the BIOS $PIR table. This is needed on
  1479. some systems with broken BIOSes, notably
  1480. some HP Pavilion N5400 and Omnibook XE3
  1481. notebooks. This will have no effect if ACPI
  1482. IRQ routing is enabled.
  1483. noacpi [X86] Do not use ACPI for IRQ routing
  1484. or for PCI scanning.
  1485. use_crs [X86] Use _CRS for PCI resource
  1486. allocation.
  1487. routeirq Do IRQ routing for all PCI devices.
  1488. This is normally done in pci_enable_device(),
  1489. so this option is a temporary workaround
  1490. for broken drivers that don't call it.
  1491. skip_isa_align [X86] do not align io start addr, so can
  1492. handle more pci cards
  1493. firmware [ARM] Do not re-enumerate the bus but instead
  1494. just use the configuration from the
  1495. bootloader. This is currently used on
  1496. IXP2000 systems where the bus has to be
  1497. configured a certain way for adjunct CPUs.
  1498. noearly [X86] Don't do any early type 1 scanning.
  1499. This might help on some broken boards which
  1500. machine check when some devices' config space
  1501. is read. But various workarounds are disabled
  1502. and some IOMMU drivers will not work.
  1503. bfsort Sort PCI devices into breadth-first order.
  1504. This sorting is done to get a device
  1505. order compatible with older (<= 2.4) kernels.
  1506. nobfsort Don't sort PCI devices into breadth-first order.
  1507. cbiosize=nn[KMG] The fixed amount of bus space which is
  1508. reserved for the CardBus bridge's IO window.
  1509. The default value is 256 bytes.
  1510. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1511. reserved for the CardBus bridge's memory
  1512. window. The default value is 64 megabytes.
  1513. resource_alignment=
  1514. Format:
  1515. [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
  1516. Specifies alignment and device to reassign
  1517. aligned memory resources.
  1518. If <order of align> is not specified,
  1519. PAGE_SIZE is used as alignment.
  1520. PCI-PCI bridge can be specified, if resource
  1521. windows need to be expanded.
  1522. ecrc= Enable/disable PCIe ECRC (transaction layer
  1523. end-to-end CRC checking).
  1524. bios: Use BIOS/firmware settings. This is the
  1525. the default.
  1526. off: Turn ECRC off
  1527. on: Turn ECRC on.
  1528. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
  1529. Management.
  1530. off Disable ASPM.
  1531. force Enable ASPM even on devices that claim not to support it.
  1532. WARNING: Forcing ASPM on may cause system lockups.
  1533. pcmv= [HW,PCMCIA] BadgePAD 4
  1534. pd. [PARIDE]
  1535. See Documentation/blockdev/paride.txt.
  1536. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1537. boot time.
  1538. Format: { 0 | 1 }
  1539. See arch/parisc/kernel/pdc_chassis.c
  1540. percpu_alloc= [X86] Select which percpu first chunk allocator to use.
  1541. Allowed values are one of "lpage", "embed" and "4k".
  1542. See comments in arch/x86/kernel/setup_percpu.c for
  1543. details on each allocator. This parameter is primarily
  1544. for debugging and performance comparison.
  1545. pf. [PARIDE]
  1546. See Documentation/blockdev/paride.txt.
  1547. pg. [PARIDE]
  1548. See Documentation/blockdev/paride.txt.
  1549. pirq= [SMP,APIC] Manual mp-table setup
  1550. See Documentation/x86/i386/IO-APIC.txt.
  1551. plip= [PPT,NET] Parallel port network link
  1552. Format: { parport<nr> | timid | 0 }
  1553. See also Documentation/parport.txt.
  1554. pmtmr= [X86] Manual setup of pmtmr I/O Port.
  1555. Override pmtimer IOPort with a hex value.
  1556. e.g. pmtmr=0x508
  1557. pnp.debug [PNP]
  1558. Enable PNP debug messages. This depends on the
  1559. CONFIG_PNP_DEBUG_MESSAGES option.
  1560. pnpacpi= [ACPI]
  1561. { off }
  1562. pnpbios= [ISAPNP]
  1563. { on | off | curr | res | no-curr | no-res }
  1564. pnp_reserve_irq=
  1565. [ISAPNP] Exclude IRQs for the autoconfiguration
  1566. pnp_reserve_dma=
  1567. [ISAPNP] Exclude DMAs for the autoconfiguration
  1568. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1569. Ranges are in pairs (I/O port base and size).
  1570. pnp_reserve_mem=
  1571. [ISAPNP] Exclude memory regions for the
  1572. autoconfiguration.
  1573. Ranges are in pairs (memory base and size).
  1574. ports= [IP_VS_FTP] IPVS ftp helper module
  1575. Default is 21.
  1576. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  1577. may be specified.
  1578. Format: <port>,<port>....
  1579. print-fatal-signals=
  1580. [KNL] debug: print fatal signals
  1581. print-fatal-signals=1: print segfault info to
  1582. the kernel console.
  1583. default: off.
  1584. printk.time= Show timing data prefixed to each printk message line
  1585. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1586. processor.max_cstate= [HW,ACPI]
  1587. Limit processor to maximum C-state
  1588. max_cstate=9 overrides any DMI blacklist limit.
  1589. processor.nocst [HW,ACPI]
  1590. Ignore the _CST method to determine C-states,
  1591. instead using the legacy FADT method
  1592. profile= [KNL] Enable kernel profiling via /proc/profile
  1593. Format: [schedule,]<number>
  1594. Param: "schedule" - profile schedule points.
  1595. Param: <number> - step/bucket size as a power of 2 for
  1596. statistical time based profiling.
  1597. Param: "sleep" - profile D-state sleeping (millisecs).
  1598. Requires CONFIG_SCHEDSTATS
  1599. Param: "kvm" - profile VM exits.
  1600. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1601. before loading.
  1602. See Documentation/blockdev/ramdisk.txt.
  1603. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1604. probe for; one of (bare|imps|exps|lifebook|any).
  1605. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1606. per second.
  1607. psmouse.resetafter= [HW,MOUSE]
  1608. Try to reset the device after so many bad packets
  1609. (0 = never).
  1610. psmouse.resolution=
  1611. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1612. psmouse.smartscroll=
  1613. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1614. 0 = disabled, 1 = enabled (default).
  1615. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1616. Format:
  1617. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1618. pt. [PARIDE]
  1619. See Documentation/blockdev/paride.txt.
  1620. pty.legacy_count=
  1621. [KNL] Number of legacy pty's. Overwrites compiled-in
  1622. default number.
  1623. quiet [KNL] Disable most log messages
  1624. r128= [HW,DRM]
  1625. raid= [HW,RAID]
  1626. See Documentation/md.txt.
  1627. ramdisk_blocksize= [RAM]
  1628. See Documentation/blockdev/ramdisk.txt.
  1629. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1630. See Documentation/blockdev/ramdisk.txt.
  1631. rcupdate.blimit= [KNL,BOOT]
  1632. Set maximum number of finished RCU callbacks to process
  1633. in one batch.
  1634. rcupdate.qhimark= [KNL,BOOT]
  1635. Set threshold of queued
  1636. RCU callbacks over which batch limiting is disabled.
  1637. rcupdate.qlowmark= [KNL,BOOT]
  1638. Set threshold of queued RCU callbacks below which
  1639. batch limiting is re-enabled.
  1640. rdinit= [KNL]
  1641. Format: <full_path>
  1642. Run specified binary instead of /init from the ramdisk,
  1643. used for early userspace startup. See initrd.
  1644. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1645. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1646. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1647. relax_domain_level=
  1648. [KNL, SMP] Set scheduler's default relax_domain_level.
  1649. See Documentation/cgroups/cpusets.txt.
  1650. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1651. reservetop= [X86-32]
  1652. Format: nn[KMG]
  1653. Reserves a hole at the top of the kernel virtual
  1654. address space.
  1655. reset_devices [KNL] Force drivers to reset the underlying device
  1656. during initialization.
  1657. resume= [SWSUSP]
  1658. Specify the partition device for software suspend
  1659. resume_offset= [SWSUSP]
  1660. Specify the offset from the beginning of the partition
  1661. given by "resume=" at which the swap header is located,
  1662. in <PAGE_SIZE> units (needed only for swap files).
  1663. See Documentation/power/swsusp-and-swap-files.txt
  1664. retain_initrd [RAM] Keep initrd memory after extraction
  1665. rhash_entries= [KNL,NET]
  1666. Set number of hash buckets for route cache
  1667. riscom8= [HW,SERIAL]
  1668. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1669. ro [KNL] Mount root device read-only on boot
  1670. root= [KNL] Root filesystem
  1671. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1672. mount the root filesystem
  1673. rootflags= [KNL] Set root filesystem mount option string
  1674. rootfstype= [KNL] Set root filesystem type
  1675. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1676. Useful for devices that are detected asynchronously
  1677. (e.g. USB and MMC devices).
  1678. root_plug.vendor_id=
  1679. [ROOTPLUG] Override the default vendor ID
  1680. root_plug.product_id=
  1681. [ROOTPLUG] Override the default product ID
  1682. root_plug.debug=
  1683. [ROOTPLUG] Enable debugging output
  1684. rw [KNL] Mount root device read-write on boot
  1685. S [KNL] Run init in single mode
  1686. sa1100ir [NET]
  1687. See drivers/net/irda/sa1100_ir.c.
  1688. sbni= [NET] Granch SBNI12 leased line adapter
  1689. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1690. Format: <io>[,<timeout>[,<isapnp>]]
  1691. scsi_debug_*= [SCSI]
  1692. See drivers/scsi/scsi_debug.c.
  1693. scsi_default_dev_flags=
  1694. [SCSI] SCSI default device flags
  1695. Format: <integer>
  1696. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1697. Format: <vendor>:<model>:<flags>
  1698. (flags are integer value)
  1699. scsi_logging_level= [SCSI] a bit mask of logging levels
  1700. See drivers/scsi/scsi_logging.h for bits. Also
  1701. settable via sysctl at dev.scsi.logging_level
  1702. (/proc/sys/dev/scsi/logging_level).
  1703. There is also a nice 'scsi_logging_level' script in the
  1704. S390-tools package, available for download at
  1705. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1706. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1707. discovered. async scans them in kernel threads,
  1708. allowing boot to proceed. none ignores them, expecting
  1709. user space to do the scan.
  1710. security= [SECURITY] Choose a security module to enable at boot.
  1711. If this boot parameter is not specified, only the first
  1712. security module asking for security registration will be
  1713. loaded. An invalid security module name will be treated
  1714. as if no module has been chosen.
  1715. selinux= [SELINUX] Disable or enable SELinux at boot time.
  1716. Format: { "0" | "1" }
  1717. See security/selinux/Kconfig help text.
  1718. 0 -- disable.
  1719. 1 -- enable.
  1720. Default value is set via kernel config option.
  1721. If enabled at boot time, /selinux/disable can be used
  1722. later to disable prior to initial policy load.
  1723. serialnumber [BUGS=X86-32]
  1724. shapers= [NET]
  1725. Maximal number of shapers.
  1726. show_msr= [x86] show boot-time MSR settings
  1727. Format: { <integer> }
  1728. Show boot-time (BIOS-initialized) MSR settings.
  1729. The parameter means the number of CPUs to show,
  1730. for example 1 means boot CPU only.
  1731. sim710= [SCSI,HW]
  1732. See header of drivers/scsi/sim710.c.
  1733. simeth= [IA-64]
  1734. simscsi=
  1735. slram= [HW,MTD]
  1736. slub_debug[=options[,slabs]] [MM, SLUB]
  1737. Enabling slub_debug allows one to determine the
  1738. culprit if slab objects become corrupted. Enabling
  1739. slub_debug can create guard zones around objects and
  1740. may poison objects when not in use. Also tracks the
  1741. last alloc / free. For more information see
  1742. Documentation/vm/slub.txt.
  1743. slub_max_order= [MM, SLUB]
  1744. Determines the maximum allowed order for slabs.
  1745. A high setting may cause OOMs due to memory
  1746. fragmentation. For more information see
  1747. Documentation/vm/slub.txt.
  1748. slub_min_objects= [MM, SLUB]
  1749. The minimum number of objects per slab. SLUB will
  1750. increase the slab order up to slub_max_order to
  1751. generate a sufficiently large slab able to contain
  1752. the number of objects indicated. The higher the number
  1753. of objects the smaller the overhead of tracking slabs
  1754. and the less frequently locks need to be acquired.
  1755. For more information see Documentation/vm/slub.txt.
  1756. slub_min_order= [MM, SLUB]
  1757. Determines the mininum page order for slabs. Must be
  1758. lower than slub_max_order.
  1759. For more information see Documentation/vm/slub.txt.
  1760. slub_nomerge [MM, SLUB]
  1761. Disable merging of slabs with similar size. May be
  1762. necessary if there is some reason to distinguish
  1763. allocs to different slabs. Debug options disable
  1764. merging on their own.
  1765. For more information see Documentation/vm/slub.txt.
  1766. smart2= [HW]
  1767. Format: <io1>[,<io2>[,...,<io8>]]
  1768. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1769. attempt to substitute SMP alternatives once at boot.
  1770. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1771. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1772. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1773. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1774. smsc-ircc2.ircc_irq= [HW] IRQ line
  1775. smsc-ircc2.ircc_dma= [HW] DMA channel
  1776. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1777. 0: Toshiba Satellite 1800 (GP data pin select)
  1778. 1: Fast pin select (default)
  1779. 2: ATC IRMode
  1780. snd-ad1816a= [HW,ALSA]
  1781. snd-ad1848= [HW,ALSA]
  1782. snd-ali5451= [HW,ALSA]
  1783. snd-als100= [HW,ALSA]
  1784. snd-als4000= [HW,ALSA]
  1785. snd-azt2320= [HW,ALSA]
  1786. snd-cmi8330= [HW,ALSA]
  1787. snd-cmipci= [HW,ALSA]
  1788. snd-cs4231= [HW,ALSA]
  1789. snd-cs4232= [HW,ALSA]
  1790. snd-cs4236= [HW,ALSA]
  1791. snd-cs4281= [HW,ALSA]
  1792. snd-cs46xx= [HW,ALSA]
  1793. snd-dt019x= [HW,ALSA]
  1794. snd-dummy= [HW,ALSA]
  1795. snd-emu10k1= [HW,ALSA]
  1796. snd-ens1370= [HW,ALSA]
  1797. snd-ens1371= [HW,ALSA]
  1798. snd-es968= [HW,ALSA]
  1799. snd-es1688= [HW,ALSA]
  1800. snd-es18xx= [HW,ALSA]
  1801. snd-es1938= [HW,ALSA]
  1802. snd-es1968= [HW,ALSA]
  1803. snd-fm801= [HW,ALSA]
  1804. snd-gusclassic= [HW,ALSA]
  1805. snd-gusextreme= [HW,ALSA]
  1806. snd-gusmax= [HW,ALSA]
  1807. snd-hdsp= [HW,ALSA]
  1808. snd-ice1712= [HW,ALSA]
  1809. snd-intel8x0= [HW,ALSA]
  1810. snd-interwave= [HW,ALSA]
  1811. snd-interwave-stb=
  1812. [HW,ALSA]
  1813. snd-korg1212= [HW,ALSA]
  1814. snd-maestro3= [HW,ALSA]
  1815. snd-mpu401= [HW,ALSA]
  1816. snd-mtpav= [HW,ALSA]
  1817. snd-nm256= [HW,ALSA]
  1818. snd-opl3sa2= [HW,ALSA]
  1819. snd-opti92x-ad1848=
  1820. [HW,ALSA]
  1821. snd-opti92x-cs4231=
  1822. [HW,ALSA]
  1823. snd-opti93x= [HW,ALSA]
  1824. snd-pmac= [HW,ALSA]
  1825. snd-rme32= [HW,ALSA]
  1826. snd-rme96= [HW,ALSA]
  1827. snd-rme9652= [HW,ALSA]
  1828. snd-sb8= [HW,ALSA]
  1829. snd-sb16= [HW,ALSA]
  1830. snd-sbawe= [HW,ALSA]
  1831. snd-serial= [HW,ALSA]
  1832. snd-sgalaxy= [HW,ALSA]
  1833. snd-sonicvibes= [HW,ALSA]
  1834. snd-sun-amd7930=
  1835. [HW,ALSA]
  1836. snd-sun-cs4231= [HW,ALSA]
  1837. snd-trident= [HW,ALSA]
  1838. snd-usb-audio= [HW,ALSA,USB]
  1839. snd-via82xx= [HW,ALSA]
  1840. snd-virmidi= [HW,ALSA]
  1841. snd-wavefront= [HW,ALSA]
  1842. snd-ymfpci= [HW,ALSA]
  1843. softlockup_panic=
  1844. [KNL] Should the soft-lockup detector generate panics.
  1845. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1846. See Documentation/sonypi.txt
  1847. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1848. See Documentation/serial/specialix.txt.
  1849. spia_io_base= [HW,MTD]
  1850. spia_fio_base=
  1851. spia_pedr=
  1852. spia_peddr=
  1853. sscape= [HW,OSS]
  1854. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1855. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1856. See Documentation/scsi/st.txt.
  1857. stacktrace [FTRACE]
  1858. Enabled the stack tracer on boot up.
  1859. sti= [PARISC,HW]
  1860. Format: <num>
  1861. Set the STI (builtin display/keyboard on the HP-PARISC
  1862. machines) console (graphic card) which should be used
  1863. as the initial boot-console.
  1864. See also comment in drivers/video/console/sticore.c.
  1865. sti_font= [HW]
  1866. See comment in drivers/video/console/sticore.c.
  1867. stifb= [HW]
  1868. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1869. sunrpc.pool_mode=
  1870. [NFS]
  1871. Control how the NFS server code allocates CPUs to
  1872. service thread pools. Depending on how many NICs
  1873. you have and where their interrupts are bound, this
  1874. option will affect which CPUs will do NFS serving.
  1875. Note: this parameter cannot be changed while the
  1876. NFS server is running.
  1877. auto the server chooses an appropriate mode
  1878. automatically using heuristics
  1879. global a single global pool contains all CPUs
  1880. percpu one pool for each CPU
  1881. pernode one pool for each NUMA node (equivalent
  1882. to global on non-NUMA machines)
  1883. swiotlb= [IA-64] Number of I/O TLB slabs
  1884. switches= [HW,M68k]
  1885. sym53c416= [HW,SCSI]
  1886. See header of drivers/scsi/sym53c416.c.
  1887. sysrq_always_enabled
  1888. [KNL]
  1889. Ignore sysrq setting - this boot parameter will
  1890. neutralize any effect of /proc/sys/kernel/sysrq.
  1891. Useful for debugging.
  1892. t128= [HW,SCSI]
  1893. See header of drivers/scsi/t128.c.
  1894. tdfx= [HW,DRM]
  1895. test_suspend= [SUSPEND]
  1896. Specify "mem" (for Suspend-to-RAM) or "standby" (for
  1897. standby suspend) as the system sleep state to briefly
  1898. enter during system startup. The system is woken from
  1899. this state using a wakeup-capable RTC alarm.
  1900. thash_entries= [KNL,NET]
  1901. Set number of hash buckets for TCP connection
  1902. thermal.act= [HW,ACPI]
  1903. -1: disable all active trip points in all thermal zones
  1904. <degrees C>: override all lowest active trip points
  1905. thermal.crt= [HW,ACPI]
  1906. -1: disable all critical trip points in all thermal zones
  1907. <degrees C>: override all critical trip points
  1908. thermal.nocrt= [HW,ACPI]
  1909. Set to disable actions on ACPI thermal zone
  1910. critical and hot trip points.
  1911. thermal.off= [HW,ACPI]
  1912. 1: disable ACPI thermal control
  1913. thermal.psv= [HW,ACPI]
  1914. -1: disable all passive trip points
  1915. <degrees C>: override all passive trip points to this
  1916. value
  1917. thermal.tzp= [HW,ACPI]
  1918. Specify global default ACPI thermal zone polling rate
  1919. <deci-seconds>: poll all this frequency
  1920. 0: no polling (default)
  1921. tmscsim= [HW,SCSI]
  1922. See comment before function dc390_setup() in
  1923. drivers/scsi/tmscsim.c.
  1924. topology= [S390]
  1925. Format: {off | on}
  1926. Specify if the kernel should make use of the cpu
  1927. topology informations if the hardware supports these.
  1928. The scheduler will make use of these informations and
  1929. e.g. base its process migration decisions on it.
  1930. Default is off.
  1931. tp720= [HW,PS2]
  1932. trace_buf_size=nn[KMG]
  1933. [FTRACE] will set tracing buffer size.
  1934. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1935. Format:
  1936. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1937. tsc= Disable clocksource-must-verify flag for TSC.
  1938. Format: <string>
  1939. [x86] reliable: mark tsc clocksource as reliable, this
  1940. disables clocksource verification at runtime.
  1941. Used to enable high-resolution timer mode on older
  1942. hardware, and in virtualized environment.
  1943. turbografx.map[2|3]= [HW,JOY]
  1944. TurboGraFX parallel port interface
  1945. Format:
  1946. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1947. See also Documentation/input/joystick-parport.txt
  1948. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1949. See header of drivers/scsi/u14-34f.c.
  1950. uart401= [HW,OSS]
  1951. Format: <io>,<irq>
  1952. uart6850= [HW,OSS]
  1953. Format: <io>,<irq>
  1954. uhci-hcd.ignore_oc=
  1955. [USB] Ignore overcurrent events (default N).
  1956. Some badly-designed motherboards generate lots of
  1957. bogus events, for ports that aren't wired to
  1958. anything. Set this parameter to avoid log spamming.
  1959. Note that genuine overcurrent events won't be
  1960. reported either.
  1961. unknown_nmi_panic
  1962. [X86]
  1963. Set unknown_nmi_panic=1 early on boot.
  1964. usbcore.autosuspend=
  1965. [USB] The autosuspend time delay (in seconds) used
  1966. for newly-detected USB devices (default 2). This
  1967. is the time required before an idle device will be
  1968. autosuspended. Devices for which the delay is set
  1969. to a negative value won't be autosuspended at all.
  1970. usbcore.usbfs_snoop=
  1971. [USB] Set to log all usbfs traffic (default 0 = off).
  1972. usbcore.blinkenlights=
  1973. [USB] Set to cycle leds on hubs (default 0 = off).
  1974. usbcore.old_scheme_first=
  1975. [USB] Start with the old device initialization
  1976. scheme (default 0 = off).
  1977. usbcore.use_both_schemes=
  1978. [USB] Try the other device initialization scheme
  1979. if the first one fails (default 1 = enabled).
  1980. usbcore.initial_descriptor_timeout=
  1981. [USB] Specifies timeout for the initial 64-byte
  1982. USB_REQ_GET_DESCRIPTOR request in milliseconds
  1983. (default 5000 = 5.0 seconds).
  1984. usbhid.mousepoll=
  1985. [USBHID] The interval which mice are to be polled at.
  1986. usb-storage.delay_use=
  1987. [UMS] The delay in seconds before a new device is
  1988. scanned for Logical Units (default 5).
  1989. usb-storage.quirks=
  1990. [UMS] A list of quirks entries to supplement or
  1991. override the built-in unusual_devs list. List
  1992. entries are separated by commas. Each entry has
  1993. the form VID:PID:Flags where VID and PID are Vendor
  1994. and Product ID values (4-digit hex numbers) and
  1995. Flags is a set of characters, each corresponding
  1996. to a common usb-storage quirk flag as follows:
  1997. a = SANE_SENSE (collect more than 18 bytes
  1998. of sense data);
  1999. c = FIX_CAPACITY (decrease the reported
  2000. device capacity by one sector);
  2001. h = CAPACITY_HEURISTICS (decrease the
  2002. reported device capacity by one
  2003. sector if the number is odd);
  2004. i = IGNORE_DEVICE (don't bind to this
  2005. device);
  2006. l = NOT_LOCKABLE (don't try to lock and
  2007. unlock ejectable media);
  2008. m = MAX_SECTORS_64 (don't transfer more
  2009. than 64 sectors = 32 KB at a time);
  2010. o = CAPACITY_OK (accept the capacity
  2011. reported by the device);
  2012. r = IGNORE_RESIDUE (the device reports
  2013. bogus residue values);
  2014. s = SINGLE_LUN (the device has only one
  2015. Logical Unit);
  2016. w = NO_WP_DETECT (don't test whether the
  2017. medium is write-protected).
  2018. Example: quirks=0419:aaf5:rl,0421:0433:rc
  2019. vdso= [X86,SH]
  2020. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  2021. vdso=1: enable VDSO (default)
  2022. vdso=0: disable VDSO mapping
  2023. vdso32= [X86]
  2024. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  2025. vdso32=1: enable 32-bit VDSO (default)
  2026. vdso32=0: disable 32-bit VDSO mapping
  2027. vector= [IA-64,SMP]
  2028. vector=percpu: enable percpu vector domain
  2029. video= [FB] Frame buffer configuration
  2030. See Documentation/fb/modedb.txt.
  2031. vga= [BOOT,X86-32] Select a particular video mode
  2032. See Documentation/x86/boot.txt and
  2033. Documentation/svga.txt.
  2034. Use vga=ask for menu.
  2035. This is actually a boot loader parameter; the value is
  2036. passed to the kernel using a special protocol.
  2037. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  2038. size of <nn>. This can be used to increase the
  2039. minimum size (128MB on x86). It can also be used to
  2040. decrease the size and leave more room for directly
  2041. mapped kernel RAM.
  2042. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  2043. Format: <command>
  2044. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  2045. Format: <command>
  2046. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  2047. Format: <command>
  2048. vt.default_blu= [VT]
  2049. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  2050. Change the default blue palette of the console.
  2051. This is a 16-member array composed of values
  2052. ranging from 0-255.
  2053. vt.default_grn= [VT]
  2054. Format: <green0>,<green1>,<green2>,...,<green15>
  2055. Change the default green palette of the console.
  2056. This is a 16-member array composed of values
  2057. ranging from 0-255.
  2058. vt.default_red= [VT]
  2059. Format: <red0>,<red1>,<red2>,...,<red15>
  2060. Change the default red palette of the console.
  2061. This is a 16-member array composed of values
  2062. ranging from 0-255.
  2063. vt.default_utf8=
  2064. [VT]
  2065. Format=<0|1>
  2066. Set system-wide default UTF-8 mode for all tty's.
  2067. Default is 1, i.e. UTF-8 mode is enabled for all
  2068. newly opened terminals.
  2069. waveartist= [HW,OSS]
  2070. Format: <io>,<irq>,<dma>,<dma2>
  2071. wd33c93= [HW,SCSI]
  2072. See header of drivers/scsi/wd33c93.c.
  2073. wd7000= [HW,SCSI]
  2074. See header of drivers/scsi/wd7000.c.
  2075. wdt= [WDT] Watchdog
  2076. See Documentation/watchdog/wdt.txt.
  2077. x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
  2078. default x2apic cluster mode on platforms
  2079. supporting x2apic.
  2080. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  2081. xd_geo= See header of drivers/block/xd.c.
  2082. xirc2ps_cs= [NET,PCMCIA]
  2083. Format:
  2084. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  2085. ______________________________________________________________________
  2086. TODO:
  2087. Add documentation for ALSA options.
  2088. Add more DRM drivers.