kernel-parameters.txt 90 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. KVM Kernel Virtual Machine support is enabled.
  51. LIBATA Libata driver is enabled
  52. LP Printer support is enabled.
  53. LOOP Loopback device support is enabled.
  54. M68k M68k architecture is enabled.
  55. These options have more detailed description inside of
  56. Documentation/m68k/kernel-options.txt.
  57. MCA MCA bus support is enabled.
  58. MDA MDA console support is enabled.
  59. MOUSE Appropriate mouse support is enabled.
  60. MSI Message Signaled Interrupts (PCI).
  61. MTD MTD (Memory Technology Device) support is enabled.
  62. NET Appropriate network support is enabled.
  63. NUMA NUMA support is enabled.
  64. GENERIC_TIME The generic timeofday code is enabled.
  65. NFS Appropriate NFS support is enabled.
  66. OSS OSS sound support is enabled.
  67. PV_OPS A paravirtualized kernel is enabled.
  68. PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
  69. PARISC The PA-RISC architecture is enabled.
  70. PCI PCI bus support is enabled.
  71. PCIE PCI Express support is enabled.
  72. PCMCIA The PCMCIA subsystem is enabled.
  73. PNP Plug & Play support is enabled.
  74. PPC PowerPC architecture is enabled.
  75. PPT Parallel port support is enabled.
  76. PS2 Appropriate PS/2 support is enabled.
  77. RAM RAM disk support 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_early_pdc_eval [HW,ACPI] Evaluate processor _PDC methods
  177. early. Needed on some platforms to properly
  178. initialize the EC.
  179. acpi_irq_balance [HW,ACPI]
  180. ACPI will balance active IRQs
  181. default in APIC mode
  182. acpi_irq_nobalance [HW,ACPI]
  183. ACPI will not move active IRQs (default)
  184. default in PIC mode
  185. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  186. Format: <irq>,<irq>...
  187. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  188. use by PCI
  189. Format: <irq>,<irq>...
  190. acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
  191. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  192. Format: To spoof as Windows 98: ="Microsoft Windows"
  193. acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
  194. acpi_osi="string1" # add string1 -- only one string
  195. acpi_osi="!string2" # remove built-in string2
  196. acpi_osi= # disable all strings
  197. acpi_pm_good [X86]
  198. Override the pmtimer bug detection: force the kernel
  199. to assume that this machine's pmtimer latches its value
  200. and always returns good values.
  201. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  202. Format: { level | edge | high | low }
  203. acpi_serialize [HW,ACPI] force serialization of AML methods
  204. acpi_skip_timer_override [HW,ACPI]
  205. Recognize and ignore IRQ0/pin2 Interrupt Override.
  206. For broken nForce2 BIOS resulting in XT-PIC timer.
  207. acpi_sleep= [HW,ACPI] Sleep options
  208. Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
  209. old_ordering, s4_nonvs, sci_force_enable }
  210. See Documentation/power/video.txt for information on
  211. s3_bios and s3_mode.
  212. s3_beep is for debugging; it makes the PC's speaker beep
  213. as soon as the kernel's real-mode entry point is called.
  214. s4_nohwsig prevents ACPI hardware signature from being
  215. used during resume from hibernation.
  216. old_ordering causes the ACPI 1.0 ordering of the _PTS
  217. control method, with respect to putting devices into
  218. low power states, to be enforced (the ACPI 2.0 ordering
  219. of _PTS is used by default).
  220. s4_nonvs prevents the kernel from saving/restoring the
  221. ACPI NVS memory during hibernation.
  222. sci_force_enable causes the kernel to set SCI_EN directly
  223. on resume from S1/S3 (which is against the ACPI spec,
  224. but some broken systems don't work without it).
  225. acpi_use_timer_override [HW,ACPI]
  226. Use timer override. For some broken Nvidia NF5 boards
  227. that require a timer override, but don't have HPET
  228. acpi_enforce_resources= [ACPI]
  229. { strict | lax | no }
  230. Check for resource conflicts between native drivers
  231. and ACPI OperationRegions (SystemIO and SystemMemory
  232. only). IO ports and memory declared in ACPI might be
  233. used by the ACPI subsystem in arbitrary AML code and
  234. can interfere with legacy drivers.
  235. strict (default): access to resources claimed by ACPI
  236. is denied; legacy drivers trying to access reserved
  237. resources will fail to bind to device using them.
  238. lax: access to resources claimed by ACPI is allowed;
  239. legacy drivers trying to access reserved resources
  240. will bind successfully but a warning message is logged.
  241. no: ACPI OperationRegions are not marked as reserved,
  242. no further checks are performed.
  243. ad1848= [HW,OSS]
  244. Format: <io>,<irq>,<dma>,<dma2>,<type>
  245. add_efi_memmap [EFI; X86] Include EFI memory map in
  246. kernel's map of available physical RAM.
  247. advansys= [HW,SCSI]
  248. See header of drivers/scsi/advansys.c.
  249. advwdt= [HW,WDT] Advantech WDT
  250. Format: <iostart>,<iostop>
  251. aedsp16= [HW,OSS] Audio Excel DSP 16
  252. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  253. See also header of sound/oss/aedsp16.c.
  254. agp= [AGP]
  255. { off | try_unsupported }
  256. off: disable AGP support
  257. try_unsupported: try to drive unsupported chipsets
  258. (may crash computer or cause data corruption)
  259. aha152x= [HW,SCSI]
  260. See Documentation/scsi/aha152x.txt.
  261. aha1542= [HW,SCSI]
  262. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  263. aic7xxx= [HW,SCSI]
  264. See Documentation/scsi/aic7xxx.txt.
  265. aic79xx= [HW,SCSI]
  266. See Documentation/scsi/aic79xx.txt.
  267. alignment= [KNL,ARM]
  268. Allow the default userspace alignment fault handler
  269. behaviour to be specified. Bit 0 enables warnings,
  270. bit 1 enables fixups, and bit 2 sends a segfault.
  271. amd_iommu= [HW,X86-84]
  272. Pass parameters to the AMD IOMMU driver in the system.
  273. Possible values are:
  274. isolate - enable device isolation (each device, as far
  275. as possible, will get its own protection
  276. domain) [default]
  277. share - put every device behind one IOMMU into the
  278. same protection domain
  279. fullflush - enable flushing of IO/TLB entries when
  280. they are unmapped. Otherwise they are
  281. flushed before they will be reused, which
  282. is a lot of faster
  283. amijoy.map= [HW,JOY] Amiga joystick support
  284. Map of devices attached to JOY0DAT and JOY1DAT
  285. Format: <a>,<b>
  286. See also Documentation/kernel/input/joystick.txt
  287. analog.map= [HW,JOY] Analog joystick and gamepad support
  288. Specifies type or capabilities of an analog joystick
  289. connected to one of 16 gameports
  290. Format: <type1>,<type2>,..<type16>
  291. apc= [HW,SPARC]
  292. Power management functions (SPARCstation-4/5 + deriv.)
  293. Format: noidle
  294. Disable APC CPU standby support. SPARCstation-Fox does
  295. not play well with APC CPU idle - disable it if you have
  296. APC and your system crashes randomly.
  297. apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
  298. Change the output verbosity whilst booting
  299. Format: { quiet (default) | verbose | debug }
  300. Change the amount of debugging information output
  301. when initialising the APIC and IO-APIC components.
  302. show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
  303. Limit apic dumping. The parameter defines the maximal
  304. number of local apics being dumped. Also it is possible
  305. to set it to "all" by meaning -- no limit here.
  306. Format: { 1 (default) | 2 | ... | all }.
  307. The parameter valid if only apic=debug or
  308. apic=verbose is specified.
  309. Example: apic=debug show_lapic=all
  310. apm= [APM] Advanced Power Management
  311. See header of arch/x86/kernel/apm_32.c.
  312. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  313. Format: <io>,<irq>,<nodeID>
  314. ataflop= [HW,M68k]
  315. atarimouse= [HW,MOUSE] Atari Mouse
  316. atascsi= [HW,SCSI] Atari SCSI
  317. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  318. EzKey and similar keyboards
  319. atkbd.reset= [HW] Reset keyboard during initialization
  320. atkbd.set= [HW] Select keyboard code set
  321. Format: <int> (2 = AT (default), 3 = PS/2)
  322. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  323. keyboards
  324. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  325. Format: <bool> (0 = real, 1 = synthetic (default))
  326. atkbd.softrepeat= [HW]
  327. Use software keyboard repeat
  328. autotest [IA64]
  329. baycom_epp= [HW,AX25]
  330. Format: <io>,<mode>
  331. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  332. Format: <io>,<mode>
  333. See header of drivers/net/hamradio/baycom_par.c.
  334. baycom_ser_fdx= [HW,AX25]
  335. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  336. Format: <io>,<irq>,<mode>[,<baud>]
  337. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  338. baycom_ser_hdx= [HW,AX25]
  339. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  340. Format: <io>,<irq>,<mode>
  341. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  342. boot_delay= Milliseconds to delay each printk during boot.
  343. Values larger than 10 seconds (10000) are changed to
  344. no delay (0).
  345. Format: integer
  346. bootmem_debug [KNL] Enable bootmem allocator debug messages.
  347. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  348. bttv.radio= Most important insmod options are available as
  349. kernel args too.
  350. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  351. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  352. BusLogic= [HW,SCSI]
  353. See drivers/scsi/BusLogic.c, comment before function
  354. BusLogic_ParseDriverOptions().
  355. c101= [NET] Moxa C101 synchronous serial card
  356. cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
  357. Sometimes CPU hardware bugs make them report the cache
  358. size incorrectly. The kernel will attempt work arounds
  359. to fix known problems, but for some CPUs it is not
  360. possible to determine what the correct size should be.
  361. This option provides an override for these situations.
  362. capability.disable=
  363. [SECURITY] Disable capabilities. This would normally
  364. be used only if an alternative security model is to be
  365. configured. Potentially dangerous and should only be
  366. used if you are entirely sure of the consequences.
  367. ccw_timeout_log [S390]
  368. See Documentation/s390/CommonIO for details.
  369. cgroup_disable= [KNL] Disable a particular controller
  370. Format: {name of the controller(s) to disable}
  371. {Currently supported controllers - "memory"}
  372. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  373. Format: { "0" | "1" }
  374. See security/selinux/Kconfig help text.
  375. 0 -- check protection applied by kernel (includes
  376. any implied execute protection).
  377. 1 -- check protection requested by application.
  378. Default value is set via a kernel config option.
  379. Value can be changed at runtime via
  380. /selinux/checkreqprot.
  381. cio_ignore= [S390]
  382. See Documentation/s390/CommonIO for details.
  383. clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
  384. [Deprecated]
  385. Forces specified clocksource (if available) to be used
  386. when calculating gettimeofday(). If specified
  387. clocksource is not available, it defaults to PIT.
  388. Format: { pit | tsc | cyclone | pmtmr }
  389. clocksource= [GENERIC_TIME] Override the default clocksource
  390. Format: <string>
  391. Override the default clocksource and use the clocksource
  392. with the name specified.
  393. Some clocksource names to choose from, depending on
  394. the platform:
  395. [all] jiffies (this is the base, fallback clocksource)
  396. [ACPI] acpi_pm
  397. [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
  398. pxa_timer,timer3,32k_counter,timer0_1
  399. [AVR32] avr32
  400. [X86-32] pit,hpet,tsc,vmi-timer;
  401. scx200_hrt on Geode; cyclone on IBM x440
  402. [MIPS] MIPS
  403. [PARISC] cr16
  404. [S390] tod
  405. [SH] SuperH
  406. [SPARC64] tick
  407. [X86-64] hpet,tsc
  408. clearcpuid=BITNUM [X86]
  409. Disable CPUID feature X for the kernel. See
  410. arch/x86/include/asm/cpufeature.h for the valid bit
  411. numbers. Note the Linux specific bits are not necessarily
  412. stable over kernel options, but the vendor specific
  413. ones should be.
  414. Also note that user programs calling CPUID directly
  415. or using the feature without checking anything
  416. will still see it. This just prevents it from
  417. being used by the kernel or shown in /proc/cpuinfo.
  418. Also note the kernel might malfunction if you disable
  419. some critical bits.
  420. cmo_free_hint= [PPC] Format: { yes | no }
  421. Specify whether pages are marked as being inactive
  422. when they are freed. This is used in CMO environments
  423. to determine OS memory pressure for page stealing by
  424. a hypervisor.
  425. Default: yes
  426. code_bytes [X86] How many bytes of object code to print
  427. in an oops report.
  428. Range: 0 - 8192
  429. Default: 64
  430. com20020= [HW,NET] ARCnet - COM20020 chipset
  431. Format:
  432. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  433. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  434. Format: <io>[,<irq>]
  435. com90xx= [HW,NET]
  436. ARCnet - COM90xx chipset (memory-mapped buffers)
  437. Format: <io>[,<irq>[,<memstart>]]
  438. condev= [HW,S390] console device
  439. conmode=
  440. console= [KNL] Output console device and options.
  441. tty<n> Use the virtual console device <n>.
  442. ttyS<n>[,options]
  443. ttyUSB0[,options]
  444. Use the specified serial port. The options are of
  445. the form "bbbbpnf", where "bbbb" is the baud rate,
  446. "p" is parity ("n", "o", or "e"), "n" is number of
  447. bits, and "f" is flow control ("r" for RTS or
  448. omit it). Default is "9600n8".
  449. See Documentation/serial-console.txt for more
  450. information. See
  451. Documentation/networking/netconsole.txt for an
  452. alternative.
  453. uart[8250],io,<addr>[,options]
  454. uart[8250],mmio,<addr>[,options]
  455. Start an early, polled-mode console on the 8250/16550
  456. UART at the specified I/O port or MMIO address,
  457. switching to the matching ttyS device later. The
  458. options are the same as for ttyS, above.
  459. If the device connected to the port is not a TTY but a braille
  460. device, prepend "brl," before the device type, for instance
  461. console=brl,ttyS0
  462. For now, only VisioBraille is supported.
  463. consoleblank= [KNL] The console blank (screen saver) timeout in
  464. seconds. Defaults to 10*60 = 10mins. A value of 0
  465. disables the blank timer.
  466. coredump_filter=
  467. [KNL] Change the default value for
  468. /proc/<pid>/coredump_filter.
  469. See also Documentation/filesystems/proc.txt.
  470. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  471. Format:
  472. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  473. crashkernel=nn[KMG]@ss[KMG]
  474. [KNL] Reserve a chunk of physical memory to
  475. hold a kernel to switch to with kexec on panic.
  476. crashkernel=range1:size1[,range2:size2,...][@offset]
  477. [KNL] Same as above, but depends on the memory
  478. in the running system. The syntax of range is
  479. start-[end] where start and end are both
  480. a memory unit (amount[KMG]). See also
  481. Documentation/kdump/kdump.txt for a example.
  482. cs89x0_dma= [HW,NET]
  483. Format: <dma>
  484. cs89x0_media= [HW,NET]
  485. Format: { rj45 | aui | bnc }
  486. dasd= [HW,NET]
  487. See header of drivers/s390/block/dasd_devmap.c.
  488. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  489. (one device per port)
  490. Format: <port#>,<type>
  491. See also Documentation/input/joystick-parport.txt
  492. debug [KNL] Enable kernel debugging (events log level).
  493. debug_locks_verbose=
  494. [KNL] verbose self-tests
  495. Format=<0|1>
  496. Print debugging info while doing the locking API
  497. self-tests.
  498. We default to 0 (no extra messages), setting it to
  499. 1 will print _a lot_ more information - normally
  500. only useful to kernel developers.
  501. debug_objects [KNL] Enable object debugging
  502. no_debug_objects
  503. [KNL] Disable object debugging
  504. debugpat [X86] Enable PAT debugging
  505. decnet.addr= [HW,NET]
  506. Format: <area>[,<node>]
  507. See also Documentation/networking/decnet.txt.
  508. default_hugepagesz=
  509. [same as hugepagesz=] The size of the default
  510. HugeTLB page size. This is the size represented by
  511. the legacy /proc/ hugepages APIs, used for SHM, and
  512. default size when mounting hugetlbfs filesystems.
  513. Defaults to the default architecture's huge page size
  514. if not specified.
  515. dhash_entries= [KNL]
  516. Set number of hash buckets for dentry cache.
  517. digi= [HW,SERIAL]
  518. IO parameters + enable/disable command.
  519. digiepca= [HW,SERIAL]
  520. See drivers/char/README.epca and
  521. Documentation/serial/digiepca.txt.
  522. disable_mtrr_cleanup [X86]
  523. The kernel tries to adjust MTRR layout from continuous
  524. to discrete, to make X server driver able to add WB
  525. entry later. This parameter disables that.
  526. disable_mtrr_trim [X86, Intel and AMD only]
  527. By default the kernel will trim any uncacheable
  528. memory out of your available memory pool based on
  529. MTRR settings. This parameter disables that behavior,
  530. possibly causing your machine to run very slowly.
  531. disable_timer_pin_1 [X86]
  532. Disable PIN 1 of APIC timer
  533. Can be useful to work around chipset bugs.
  534. dmasound= [HW,OSS] Sound subsystem buffers
  535. dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
  536. this option disables the debugging code at boot.
  537. dma_debug_entries=<number>
  538. This option allows to tune the number of preallocated
  539. entries for DMA-API debugging code. One entry is
  540. required per DMA-API allocation. Use this if the
  541. DMA-API debugging code disables itself because the
  542. architectural default is too low.
  543. dma_debug_driver=<driver_name>
  544. With this option the DMA-API debugging driver
  545. filter feature can be enabled at boot time. Just
  546. pass the driver to filter for as the parameter.
  547. The filter can be disabled or changed to another
  548. driver later using sysfs.
  549. dscc4.setup= [NET]
  550. dtc3181e= [HW,SCSI]
  551. dynamic_printk Enables pr_debug()/dev_dbg() calls if
  552. CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
  553. These can also be switched on/off via
  554. <debugfs>/dynamic_printk/modules
  555. earlycon= [KNL] Output early console device and options.
  556. uart[8250],io,<addr>[,options]
  557. uart[8250],mmio,<addr>[,options]
  558. Start an early, polled-mode console on the 8250/16550
  559. UART at the specified I/O port or MMIO address.
  560. The options are the same as for ttyS, above.
  561. earlyprintk= [X86,SH,BLACKFIN]
  562. earlyprintk=vga
  563. earlyprintk=serial[,ttySn[,baudrate]]
  564. earlyprintk=ttySn[,baudrate]
  565. earlyprintk=dbgp[debugController#]
  566. Append ",keep" to not disable it when the real console
  567. takes over.
  568. Only vga or serial or usb debug port at a time.
  569. Currently only ttyS0 and ttyS1 are supported.
  570. Interaction with the standard serial driver is not
  571. very good.
  572. The VGA output is eventually overwritten by the real
  573. console.
  574. eata= [HW,SCSI]
  575. edd= [EDD]
  576. Format: {"off" | "on" | "skip[mbr]"}
  577. eisa_irq_edge= [PARISC,HW]
  578. See header of drivers/parisc/eisa.c.
  579. elanfreq= [X86-32]
  580. See comment before function elanfreq_setup() in
  581. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
  582. elevator= [IOSCHED]
  583. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  584. See Documentation/block/as-iosched.txt and
  585. Documentation/block/deadline-iosched.txt for details.
  586. elfcorehdr= [IA64,PPC,SH,X86]
  587. Specifies physical address of start of kernel core
  588. image elf header. Generally kexec loader will
  589. pass this option to capture kernel.
  590. See Documentation/kdump/kdump.txt for details.
  591. enable_mtrr_cleanup [X86]
  592. The kernel tries to adjust MTRR layout from continuous
  593. to discrete, to make X server driver able to add WB
  594. entry later. This parameter enables that.
  595. enable_timer_pin_1 [X86]
  596. Enable PIN 1 of APIC timer
  597. Can be useful to work around chipset bugs
  598. (in particular on some ATI chipsets).
  599. The kernel tries to set a reasonable default.
  600. enforcing [SELINUX] Set initial enforcing status.
  601. Format: {"0" | "1"}
  602. See security/selinux/Kconfig help text.
  603. 0 -- permissive (log only, no denials).
  604. 1 -- enforcing (deny and log).
  605. Default value is 0.
  606. Value can be changed at runtime via /selinux/enforce.
  607. ether= [HW,NET] Ethernet cards parameters
  608. This option is obsoleted by the "netdev=" option, which
  609. has equivalent usage. See its documentation for details.
  610. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  611. Format: <io>[,<irq>]
  612. failslab=
  613. fail_page_alloc=
  614. fail_make_request=[KNL]
  615. General fault injection mechanism.
  616. Format: <interval>,<probability>,<space>,<times>
  617. See also /Documentation/fault-injection/.
  618. fd_mcs= [HW,SCSI]
  619. See header of drivers/scsi/fd_mcs.c.
  620. fdomain= [HW,SCSI]
  621. See header of drivers/scsi/fdomain.c.
  622. floppy= [HW]
  623. See Documentation/blockdev/floppy.txt.
  624. force_pal_cache_flush
  625. [IA-64] Avoid check_sal_cache_flush which may hang on
  626. buggy SAL_CACHE_FLUSH implementations. Using this
  627. parameter will force ia64_sal_cache_flush to call
  628. ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
  629. ftrace=[tracer]
  630. [FTRACE] will set and start the specified tracer
  631. as early as possible in order to facilitate early
  632. boot debugging.
  633. ftrace_dump_on_oops
  634. [FTRACE] will dump the trace buffers on oops.
  635. ftrace_filter=[function-list]
  636. [FTRACE] Limit the functions traced by the function
  637. tracer at boot up. function-list is a comma separated
  638. list of functions. This list can be changed at run
  639. time by the set_ftrace_filter file in the debugfs
  640. tracing directory.
  641. ftrace_notrace=[function-list]
  642. [FTRACE] Do not trace the functions specified in
  643. function-list. This list can be changed at run time
  644. by the set_ftrace_notrace file in the debugfs
  645. tracing directory.
  646. ftrace_graph_filter=[function-list]
  647. [FTRACE] Limit the top level callers functions traced
  648. by the function graph tracer at boot up.
  649. function-list is a comma separated list of functions
  650. that can be changed at run time by the
  651. set_graph_function file in the debugfs tracing directory.
  652. gamecon.map[2|3]=
  653. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  654. support via parallel port (up to 5 devices per port)
  655. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  656. See also Documentation/input/joystick-parport.txt
  657. gamma= [HW,DRM]
  658. gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
  659. Format: off | on
  660. default: on
  661. gcov_persist= [GCOV] When non-zero (default), profiling data for
  662. kernel modules is saved and remains accessible via
  663. debugfs, even when the module is unloaded/reloaded.
  664. When zero, profiling data is discarded and associated
  665. debugfs files are removed at module unload time.
  666. gdth= [HW,SCSI]
  667. See header of drivers/scsi/gdth.c.
  668. gpt [EFI] Forces disk with valid GPT signature but
  669. invalid Protective MBR to be treated as GPT.
  670. gvp11= [HW,SCSI]
  671. hashdist= [KNL,NUMA] Large hashes allocated during boot
  672. are distributed across NUMA nodes. Defaults on
  673. for 64bit NUMA, off otherwise.
  674. Format: 0 | 1 (for off | on)
  675. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  676. hd= [EIDE] (E)IDE hard drive subsystem geometry
  677. Format: <cyl>,<head>,<sect>
  678. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  679. size of <nn>. This works even on boxes that have no
  680. highmem otherwise. This also works to reduce highmem
  681. size on bigger boxes.
  682. highres= [KNL] Enable/disable high resolution timer mode.
  683. Valid parameters: "on", "off"
  684. Default: "on"
  685. hisax= [HW,ISDN]
  686. See Documentation/isdn/README.HiSax.
  687. hlt [BUGS=ARM,SH]
  688. hpet= [X86-32,HPET] option to control HPET usage
  689. Format: { enable (default) | disable | force |
  690. verbose }
  691. disable: disable HPET and use PIT instead
  692. force: allow force enabled of undocumented chips (ICH4,
  693. VIA, nVidia)
  694. verbose: show contents of HPET registers during setup
  695. hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
  696. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
  697. On x86-64 and powerpc, this option can be specified
  698. multiple times interleaved with hugepages= to reserve
  699. huge pages of different sizes. Valid pages sizes on
  700. x86-64 are 2M (when the CPU supports "pse") and 1G
  701. (when the CPU supports the "pdpe1gb" cpuinfo flag)
  702. Note that 1GB pages can only be allocated at boot time
  703. using hugepages= and not freed afterwards.
  704. hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
  705. terminal devices. Valid values: 0..8
  706. hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
  707. If specified, z/VM IUCV HVC accepts connections
  708. from listed z/VM user IDs only.
  709. i2c_bus= [HW] Override the default board specific I2C bus speed
  710. or register an additional I2C bus that is not
  711. registered from board initialization code.
  712. Format:
  713. <bus_id>,<clkrate>
  714. i8042.debug [HW] Toggle i8042 debug mode
  715. i8042.direct [HW] Put keyboard port into non-translated mode
  716. i8042.dumbkbd [HW] Pretend that controller can only read data from
  717. keyboard and cannot control its state
  718. (Don't attempt to blink the leds)
  719. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  720. i8042.nokbd [HW] Don't check/create keyboard port
  721. i8042.noloop [HW] Disable the AUX Loopback command while probing
  722. for the AUX port
  723. i8042.nomux [HW] Don't check presence of an active multiplexing
  724. controller
  725. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  726. controllers
  727. i8042.panicblink=
  728. [HW] Frequency with which keyboard LEDs should blink
  729. when kernel panics (default is 0.5 sec)
  730. i8042.reset [HW] Reset the controller during init and cleanup
  731. i8042.unlock [HW] Unlock (ignore) the keylock
  732. i810= [HW,DRM]
  733. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  734. indicates that the driver is running on unsupported
  735. hardware.
  736. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  737. does not match list of supported models.
  738. i8k.power_status
  739. [HW] Report power status in /proc/i8k
  740. (disabled by default)
  741. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  742. capability is set.
  743. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  744. See Documentation/mca.txt.
  745. icn= [HW,ISDN]
  746. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  747. ide-core.nodma= [HW] (E)IDE subsystem
  748. Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
  749. .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
  750. .cdrom .chs .ignore_cable are additional options
  751. See Documentation/ide/ide.txt.
  752. ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
  753. Claim all unknown PCI IDE storage controllers.
  754. idle= [X86]
  755. Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
  756. Poll forces a polling idle loop that can slightly
  757. improve the performance of waking up a idle CPU, but
  758. will use a lot of power and make the system run hot.
  759. Not recommended.
  760. idle=mwait: On systems which support MONITOR/MWAIT but
  761. the kernel chose to not use it because it doesn't save
  762. as much power as a normal idle loop, use the
  763. MONITOR/MWAIT idle loop anyways. Performance should be
  764. the same as idle=poll.
  765. idle=halt: Halt is forced to be used for CPU idle.
  766. In such case C2/C3 won't be used again.
  767. idle=nomwait: Disable mwait for CPU C-states
  768. ignore_loglevel [KNL]
  769. Ignore loglevel setting - this will print /all/
  770. kernel messages to the console. Useful for debugging.
  771. ihash_entries= [KNL]
  772. Set number of hash buckets for inode cache.
  773. ima_audit= [IMA]
  774. Format: { "0" | "1" }
  775. 0 -- integrity auditing messages. (Default)
  776. 1 -- enable informational integrity auditing messages.
  777. ima_hash= [IMA]
  778. Format: { "sha1" | "md5" }
  779. default: "sha1"
  780. ima_tcb [IMA]
  781. Load a policy which meets the needs of the Trusted
  782. Computing Base. This means IMA will measure all
  783. programs exec'd, files mmap'd for exec, and all files
  784. opened for read by uid=0.
  785. in2000= [HW,SCSI]
  786. See header of drivers/scsi/in2000.c.
  787. init= [KNL]
  788. Format: <full_path>
  789. Run specified binary instead of /sbin/init as init
  790. process.
  791. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  792. for working out where the kernel is dying during
  793. startup.
  794. initrd= [BOOT] Specify the location of the initial ramdisk
  795. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  796. Format: <irq>
  797. intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
  798. on
  799. Enable intel iommu driver.
  800. off
  801. Disable intel iommu driver.
  802. igfx_off [Default Off]
  803. By default, gfx is mapped as normal device. If a gfx
  804. device has a dedicated DMAR unit, the DMAR unit is
  805. bypassed by not enabling DMAR with this option. In
  806. this case, gfx device will use physical address for
  807. DMA.
  808. forcedac [x86_64]
  809. With this option iommu will not optimize to look
  810. for io virtual address below 32 bit forcing dual
  811. address cycle on pci bus for cards supporting greater
  812. than 32 bit addressing. The default is to look
  813. for translation below 32 bit and if not available
  814. then look in the higher range.
  815. strict [Default Off]
  816. With this option on every unmap_single operation will
  817. result in a hardware IOTLB flush operation as opposed
  818. to batching them for performance.
  819. inttest= [IA64]
  820. iomem= Disable strict checking of access to MMIO memory
  821. strict regions from userspace.
  822. relaxed
  823. iommu= [x86]
  824. off
  825. force
  826. noforce
  827. biomerge
  828. panic
  829. nopanic
  830. merge
  831. nomerge
  832. forcesac
  833. soft
  834. pt [x86, IA64]
  835. io7= [HW] IO7 for Marvel based alpha systems
  836. See comment before marvel_specify_io7 in
  837. arch/alpha/kernel/core_marvel.c.
  838. io_delay= [X86] I/O delay method
  839. 0x80
  840. Standard port 0x80 based delay
  841. 0xed
  842. Alternate port 0xed based delay (needed on some systems)
  843. udelay
  844. Simple two microseconds delay
  845. none
  846. No delay
  847. ip= [IP_PNP]
  848. See Documentation/filesystems/nfs/nfsroot.txt.
  849. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  850. See comment before ip2_setup() in
  851. drivers/char/ip2/ip2base.c.
  852. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  853. See header of drivers/scsi/ips.c.
  854. irqfixup [HW]
  855. When an interrupt is not handled search all handlers
  856. for it. Intended to get systems with badly broken
  857. firmware running.
  858. irqpoll [HW]
  859. When an interrupt is not handled search all handlers
  860. for it. Also check all handlers each timer
  861. interrupt. Intended to get systems with badly broken
  862. firmware running.
  863. isapnp= [ISAPNP]
  864. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  865. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  866. Format:
  867. <cpu number>,...,<cpu number>
  868. or
  869. <cpu number>-<cpu number>
  870. (must be a positive range in ascending order)
  871. or a mixture
  872. <cpu number>,...,<cpu number>-<cpu number>
  873. This option can be used to specify one or more CPUs
  874. to isolate from the general SMP balancing and scheduling
  875. algorithms. You can move a process onto or off an
  876. "isolated" CPU via the CPU affinity syscalls or cpuset.
  877. <cpu number> begins at 0 and the maximum value is
  878. "number of CPUs in system - 1".
  879. This option is the preferred way to isolate CPUs. The
  880. alternative -- manually setting the CPU mask of all
  881. tasks in the system -- can cause problems and
  882. suboptimal load balancer performance.
  883. iucv= [HW,NET]
  884. js= [HW,JOY] Analog joystick
  885. See Documentation/input/joystick.txt.
  886. keepinitrd [HW,ARM]
  887. kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  888. specifies the amount of memory usable by the kernel
  889. for non-movable allocations. The requested amount is
  890. spread evenly throughout all nodes in the system. The
  891. remaining memory in each node is used for Movable
  892. pages. In the event, a node is too small to have both
  893. kernelcore and Movable pages, kernelcore pages will
  894. take priority and other nodes will have a larger number
  895. of kernelcore pages. The Movable zone is used for the
  896. allocation of pages that may be reclaimed or moved
  897. by the page migration subsystem. This means that
  898. HugeTLB pages may not be allocated from this zone.
  899. Note that allocations like PTEs-from-HighMem still
  900. use the HighMem zone if it exists, and the Normal
  901. zone if it does not.
  902. kgdboc= [HW] kgdb over consoles.
  903. Requires a tty driver that supports console polling.
  904. (only serial supported for now)
  905. Format: <serial_device>[,baud]
  906. kmac= [MIPS] korina ethernet MAC address.
  907. Configure the RouterBoard 532 series on-chip
  908. Ethernet adapter MAC address.
  909. kmemleak= [KNL] Boot-time kmemleak enable/disable
  910. Valid arguments: on, off
  911. Default: on
  912. kstack=N [X86] Print N words from the kernel stack
  913. in oops dumps.
  914. kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
  915. Default is 0 (don't ignore, but inject #GP)
  916. kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
  917. Default is 1 (enabled)
  918. kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
  919. Default is 0 (off)
  920. kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
  921. for all guests.
  922. Default is 1 (enabled) if in 64bit or 32bit-PAE mode
  923. kvm-intel.bypass_guest_pf=
  924. [KVM,Intel] Disables bypassing of guest page faults
  925. on Intel chips. Default is 1 (enabled)
  926. kvm-intel.ept= [KVM,Intel] Disable extended page tables
  927. (virtualized MMU) support on capable Intel chips.
  928. Default is 1 (enabled)
  929. kvm-intel.emulate_invalid_guest_state=
  930. [KVM,Intel] Enable emulation of invalid guest states
  931. Default is 0 (disabled)
  932. kvm-intel.flexpriority=
  933. [KVM,Intel] Disable FlexPriority feature (TPR shadow).
  934. Default is 1 (enabled)
  935. kvm-intel.unrestricted_guest=
  936. [KVM,Intel] Disable unrestricted guest feature
  937. (virtualized real and unpaged mode) on capable
  938. Intel chips. Default is 1 (enabled)
  939. kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
  940. feature (tagged TLBs) on capable Intel chips.
  941. Default is 1 (enabled)
  942. l2cr= [PPC]
  943. l3cr= [PPC]
  944. lapic [X86-32,APIC] Enable the local APIC even if BIOS
  945. disabled it.
  946. lapic_timer_c2_ok [X86,APIC] trust the local apic timer
  947. in C2 power state.
  948. libata.dma= [LIBATA] DMA control
  949. libata.dma=0 Disable all PATA and SATA DMA
  950. libata.dma=1 PATA and SATA Disk DMA only
  951. libata.dma=2 ATAPI (CDROM) DMA only
  952. libata.dma=4 Compact Flash DMA only
  953. Combinations also work, so libata.dma=3 enables DMA
  954. for disks and CDROMs, but not CFs.
  955. libata.ignore_hpa= [LIBATA] Ignore HPA limit
  956. libata.ignore_hpa=0 keep BIOS limits (default)
  957. libata.ignore_hpa=1 ignore limits, using full disk
  958. libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  959. when set.
  960. Format: <int>
  961. libata.force= [LIBATA] Force configurations. The format is comma
  962. separated list of "[ID:]VAL" where ID is
  963. PORT[:DEVICE]. PORT and DEVICE are decimal numbers
  964. matching port, link or device. Basically, it matches
  965. the ATA ID string printed on console by libata. If
  966. the whole ID part is omitted, the last PORT and DEVICE
  967. values are used. If ID hasn't been specified yet, the
  968. configuration applies to all ports, links and devices.
  969. If only DEVICE is omitted, the parameter applies to
  970. the port and all links and devices behind it. DEVICE
  971. number of 0 either selects the first device or the
  972. first fan-out link behind PMP device. It does not
  973. select the host link. DEVICE number of 15 selects the
  974. host link and device attached to it.
  975. The VAL specifies the configuration to force. As long
  976. as there's no ambiguity shortcut notation is allowed.
  977. For example, both 1.5 and 1.5G would work for 1.5Gbps.
  978. The following configurations can be forced.
  979. * Cable type: 40c, 80c, short40c, unk, ign or sata.
  980. Any ID with matching PORT is used.
  981. * SATA link speed limit: 1.5Gbps or 3.0Gbps.
  982. * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
  983. udma[/][16,25,33,44,66,100,133] notation is also
  984. allowed.
  985. * [no]ncq: Turn on or off NCQ.
  986. * nohrst, nosrst, norst: suppress hard, soft
  987. and both resets.
  988. If there are multiple matching configurations changing
  989. the same attribute, the last one is used.
  990. lmb=debug [KNL] Enable lmb debug messages.
  991. load_ramdisk= [RAM] List of ramdisks to load from floppy
  992. See Documentation/blockdev/ramdisk.txt.
  993. lockd.nlm_grace_period=P [NFS] Assign grace period.
  994. Format: <integer>
  995. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  996. Format: <integer>
  997. lockd.nlm_timeout=T [NFS] Assign timeout value.
  998. Format: <integer>
  999. lockd.nlm_udpport=M [NFS] Assign UDP port.
  1000. Format: <integer>
  1001. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  1002. Format: <irq>
  1003. loglevel= All Kernel Messages with a loglevel smaller than the
  1004. console loglevel will be printed to the console. It can
  1005. also be changed with klogd or other programs. The
  1006. loglevels are defined as follows:
  1007. 0 (KERN_EMERG) system is unusable
  1008. 1 (KERN_ALERT) action must be taken immediately
  1009. 2 (KERN_CRIT) critical conditions
  1010. 3 (KERN_ERR) error conditions
  1011. 4 (KERN_WARNING) warning conditions
  1012. 5 (KERN_NOTICE) normal but significant condition
  1013. 6 (KERN_INFO) informational
  1014. 7 (KERN_DEBUG) debug-level messages
  1015. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  1016. Format: { n | nk | nM }
  1017. n must be a power of two. The default size
  1018. is set in the kernel config file.
  1019. logo.nologo [FB] Disables display of the built-in Linux logo.
  1020. This may be used to provide more screen space for
  1021. kernel log messages and is useful when debugging
  1022. kernel boot problems.
  1023. lp=0 [LP] Specify parallel ports to use, e.g,
  1024. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  1025. lp=reset first parallel port). 'lp=0' disables the
  1026. lp=auto printer driver. 'lp=reset' (which can be
  1027. specified in addition to the ports) causes
  1028. attached printers to be reset. Using
  1029. lp=port1,port2,... specifies the parallel ports
  1030. to associate lp devices with, starting with
  1031. lp0. A port specification may be 'none' to skip
  1032. that lp device, or a parport name such as
  1033. 'parport0'. Specifying 'lp=auto' instead of a
  1034. port specification list means that device IDs
  1035. from each port should be examined, to see if
  1036. an IEEE 1284-compliant printer is attached; if
  1037. so, the driver will manage that printer.
  1038. See also header of drivers/char/lp.c.
  1039. lpj=n [KNL]
  1040. Sets loops_per_jiffy to given constant, thus avoiding
  1041. time-consuming boot-time autodetection (up to 250 ms per
  1042. CPU). 0 enables autodetection (default). To determine
  1043. the correct value for your kernel, boot with normal
  1044. autodetection and see what value is printed. Note that
  1045. on SMP systems the preset will be applied to all CPUs,
  1046. which is likely to cause problems if your CPUs need
  1047. significantly divergent settings. An incorrect value
  1048. will cause delays in the kernel to be wrong, leading to
  1049. unpredictable I/O errors and other breakage. Although
  1050. unlikely, in the extreme case this might damage your
  1051. hardware.
  1052. ltpc= [NET]
  1053. Format: <io>,<irq>,<dma>
  1054. mac5380= [HW,SCSI] Format:
  1055. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  1056. machvec= [IA64] Force the use of a particular machine-vector
  1057. (machvec) in a generic kernel.
  1058. Example: machvec=hpzx1_swiotlb
  1059. machtype= [Loongson] Share the same kernel image file between different
  1060. yeeloong laptop.
  1061. Example: machtype=lemote-yeeloong-2f-7inch
  1062. max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
  1063. than or equal to this physical address is ignored.
  1064. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  1065. should make use of. maxcpus=n : n >= 0 limits the
  1066. kernel to using 'n' processors. n=0 is a special case,
  1067. it is equivalent to "nosmp", which also disables
  1068. the IO APIC.
  1069. max_loop= [LOOP] Maximum number of loopback devices that can
  1070. be mounted
  1071. Format: <1-256>
  1072. max_luns= [SCSI] Maximum number of LUNs to probe.
  1073. Should be between 1 and 2^32-1.
  1074. max_report_luns=
  1075. [SCSI] Maximum number of LUNs received.
  1076. Should be between 1 and 16384.
  1077. mcatest= [IA-64]
  1078. mce [X86-32] Machine Check Exception
  1079. mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
  1080. md= [HW] RAID subsystems devices and level
  1081. See Documentation/md.txt.
  1082. mdacon= [MDA]
  1083. Format: <first>,<last>
  1084. Specifies range of consoles to be captured by the MDA.
  1085. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  1086. Amount of memory to be used when the kernel is not able
  1087. to see the whole system memory or for test.
  1088. [X86-32] Use together with memmap= to avoid physical
  1089. address space collisions. Without memmap= PCI devices
  1090. could be placed at addresses belonging to unused RAM.
  1091. mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
  1092. memory.
  1093. memchunk=nn[KMG]
  1094. [KNL,SH] Allow user to override the default size for
  1095. per-device physically contiguous DMA buffers.
  1096. memmap=exactmap [KNL,X86] Enable setting of an exact
  1097. E820 memory map, as specified by the user.
  1098. Such memmap=exactmap lines can be constructed based on
  1099. BIOS output or other requirements. See the memmap=nn@ss
  1100. option description.
  1101. memmap=nn[KMG]@ss[KMG]
  1102. [KNL] Force usage of a specific region of memory
  1103. Region of memory to be used, from ss to ss+nn.
  1104. memmap=nn[KMG]#ss[KMG]
  1105. [KNL,ACPI] Mark specific memory as ACPI data.
  1106. Region of memory to be used, from ss to ss+nn.
  1107. memmap=nn[KMG]$ss[KMG]
  1108. [KNL,ACPI] Mark specific memory as reserved.
  1109. Region of memory to be used, from ss to ss+nn.
  1110. Example: Exclude memory from 0x18690000-0x1869ffff
  1111. memmap=64K$0x18690000
  1112. or
  1113. memmap=0x10000$0x18690000
  1114. memory_corruption_check=0/1 [X86]
  1115. Some BIOSes seem to corrupt the first 64k of
  1116. memory when doing things like suspend/resume.
  1117. Setting this option will scan the memory
  1118. looking for corruption. Enabling this will
  1119. both detect corruption and prevent the kernel
  1120. from using the memory being corrupted.
  1121. However, its intended as a diagnostic tool; if
  1122. repeatable BIOS-originated corruption always
  1123. affects the same memory, you can use memmap=
  1124. to prevent the kernel from using that memory.
  1125. memory_corruption_check_size=size [X86]
  1126. By default it checks for corruption in the low
  1127. 64k, making this memory unavailable for normal
  1128. use. Use this parameter to scan for
  1129. corruption in more or less memory.
  1130. memory_corruption_check_period=seconds [X86]
  1131. By default it checks for corruption every 60
  1132. seconds. Use this parameter to check at some
  1133. other rate. 0 disables periodic checking.
  1134. memtest= [KNL,X86] Enable memtest
  1135. Format: <integer>
  1136. default : 0 <disable>
  1137. Specifies the number of memtest passes to be
  1138. performed. Each pass selects another test
  1139. pattern from a given set of patterns. Memtest
  1140. fills the memory with this pattern, validates
  1141. memory contents and reserves bad memory
  1142. regions that are detected.
  1143. meye.*= [HW] Set MotionEye Camera parameters
  1144. See Documentation/video4linux/meye.txt.
  1145. mfgpt_irq= [IA-32] Specify the IRQ to use for the
  1146. Multi-Function General Purpose Timers on AMD Geode
  1147. platforms.
  1148. mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
  1149. the BIOS has incorrectly applied a workaround. TinyBIOS
  1150. version 0.98 is known to be affected, 0.99 fixes the
  1151. problem by letting the user disable the workaround.
  1152. mga= [HW,DRM]
  1153. min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
  1154. physical address is ignored.
  1155. mini2440= [ARM,HW,KNL]
  1156. Format:[0..2][b][c][t]
  1157. Default: "0tb"
  1158. MINI2440 configuration specification:
  1159. 0 - The attached screen is the 3.5" TFT
  1160. 1 - The attached screen is the 7" TFT
  1161. 2 - The VGA Shield is attached (1024x768)
  1162. Leaving out the screen size parameter will not load
  1163. the TFT driver, and the framebuffer will be left
  1164. unconfigured.
  1165. b - Enable backlight. The TFT backlight pin will be
  1166. linked to the kernel VESA blanking code and a GPIO
  1167. LED. This parameter is not necessary when using the
  1168. VGA shield.
  1169. c - Enable the s3c camera interface.
  1170. t - Reserved for enabling touchscreen support. The
  1171. touchscreen support is not enabled in the mainstream
  1172. kernel as of 2.6.30, a preliminary port can be found
  1173. in the "bleeding edge" mini2440 support kernel at
  1174. http://repo.or.cz/w/linux-2.6/mini2440.git
  1175. mminit_loglevel=
  1176. [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
  1177. parameter allows control of the logging verbosity for
  1178. the additional memory initialisation checks. A value
  1179. of 0 disables mminit logging and a level of 4 will
  1180. log everything. Information is printed at KERN_DEBUG
  1181. so loglevel=8 may also need to be specified.
  1182. mousedev.tap_time=
  1183. [MOUSE] Maximum time between finger touching and
  1184. leaving touchpad surface for touch to be considered
  1185. a tap and be reported as a left button click (for
  1186. touchpads working in absolute mode only).
  1187. Format: <msecs>
  1188. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  1189. reporting absolute coordinates, such as tablets
  1190. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  1191. reporting absolute coordinates, such as tablets
  1192. movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
  1193. is similar to kernelcore except it specifies the
  1194. amount of memory used for migratable allocations.
  1195. If both kernelcore and movablecore is specified,
  1196. then kernelcore will be at *least* the specified
  1197. value but may be more. If movablecore on its own
  1198. is specified, the administrator must be careful
  1199. that the amount of memory usable for all allocations
  1200. is not too small.
  1201. mpu401= [HW,OSS]
  1202. Format: <io>,<irq>
  1203. MTD_Partition= [MTD]
  1204. Format: <name>,<region-number>,<size>,<offset>
  1205. MTD_Region= [MTD] Format:
  1206. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  1207. mtdparts= [MTD]
  1208. See drivers/mtd/cmdlinepart.c.
  1209. onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
  1210. Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
  1211. boundary - index of last SLC block on Flex-OneNAND.
  1212. The remaining blocks are configured as MLC blocks.
  1213. lock - Configure if Flex-OneNAND boundary should be locked.
  1214. Once locked, the boundary cannot be changed.
  1215. 1 indicates lock status, 0 indicates unlock status.
  1216. mtdset= [ARM]
  1217. ARM/S3C2412 JIVE boot control
  1218. See arch/arm/mach-s3c2412/mach-jive.c
  1219. mtouchusb.raw_coordinates=
  1220. [HW] Make the MicroTouch USB driver use raw coordinates
  1221. ('y', default) or cooked coordinates ('n')
  1222. mtrr_chunk_size=nn[KMG] [X86]
  1223. used for mtrr cleanup. It is largest continuous chunk
  1224. that could hold holes aka. UC entries.
  1225. mtrr_gran_size=nn[KMG] [X86]
  1226. Used for mtrr cleanup. It is granularity of mtrr block.
  1227. Default is 1.
  1228. Large value could prevent small alignment from
  1229. using up MTRRs.
  1230. mtrr_spare_reg_nr=n [X86]
  1231. Format: <integer>
  1232. Range: 0,7 : spare reg number
  1233. Default : 1
  1234. Used for mtrr cleanup. It is spare mtrr entries number.
  1235. Set to 2 or more if your graphical card needs more.
  1236. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  1237. NCR_D700= [HW,SCSI]
  1238. See header of drivers/scsi/NCR_D700.c.
  1239. ncr5380= [HW,SCSI]
  1240. ncr53c400= [HW,SCSI]
  1241. ncr53c400a= [HW,SCSI]
  1242. ncr53c406a= [HW,SCSI]
  1243. ncr53c8xx= [HW,SCSI]
  1244. netdev= [NET] Network devices parameters
  1245. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  1246. Note that mem_start is often overloaded to mean
  1247. something different and driver-specific.
  1248. This usage is only documented in each driver source
  1249. file if at all.
  1250. nf_conntrack.acct=
  1251. [NETFILTER] Enable connection tracking flow accounting
  1252. 0 to disable accounting
  1253. 1 to enable accounting
  1254. Default value depends on CONFIG_NF_CT_ACCT that is
  1255. going to be removed in 2.6.29.
  1256. nfsaddrs= [NFS]
  1257. See Documentation/filesystems/nfs/nfsroot.txt.
  1258. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  1259. See Documentation/filesystems/nfs/nfsroot.txt.
  1260. nfs.callback_tcpport=
  1261. [NFS] set the TCP port on which the NFSv4 callback
  1262. channel should listen.
  1263. nfs.cache_getent=
  1264. [NFS] sets the pathname to the program which is used
  1265. to update the NFS client cache entries.
  1266. nfs.cache_getent_timeout=
  1267. [NFS] sets the timeout after which an attempt to
  1268. update a cache entry is deemed to have failed.
  1269. nfs.idmap_cache_timeout=
  1270. [NFS] set the maximum lifetime for idmapper cache
  1271. entries.
  1272. nfs.enable_ino64=
  1273. [NFS] enable 64-bit inode numbers.
  1274. If zero, the NFS client will fake up a 32-bit inode
  1275. number for the readdir() and stat() syscalls instead
  1276. of returning the full 64-bit number.
  1277. The default is to return 64-bit inode numbers.
  1278. nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
  1279. when a NMI is triggered.
  1280. Format: [state][,regs][,debounce][,die]
  1281. nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
  1282. Format: [panic,][num]
  1283. Valid num: 0,1,2
  1284. 0 - turn nmi_watchdog off
  1285. 1 - use the IO-APIC timer for the NMI watchdog
  1286. 2 - use the local APIC for the NMI watchdog using
  1287. a performance counter. Note: This will use one
  1288. performance counter and the local APIC's performance
  1289. vector.
  1290. When panic is specified, panic when an NMI watchdog
  1291. timeout occurs.
  1292. This is useful when you use a panic=... timeout and
  1293. need the box quickly up again.
  1294. Instead of 1 and 2 it is possible to use the following
  1295. symbolic names: lapic and ioapic
  1296. Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
  1297. netpoll.carrier_timeout=
  1298. [NET] Specifies amount of time (in seconds) that
  1299. netpoll should wait for a carrier. By default netpoll
  1300. waits 4 seconds.
  1301. no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
  1302. emulation library even if a 387 maths coprocessor
  1303. is present.
  1304. no_console_suspend
  1305. [HW] Never suspend the console
  1306. Disable suspending of consoles during suspend and
  1307. hibernate operations. Once disabled, debugging
  1308. messages can reach various consoles while the rest
  1309. of the system is being put to sleep (ie, while
  1310. debugging driver suspend/resume hooks). This may
  1311. not work reliably with all consoles, but is known
  1312. to work with serial and VGA consoles.
  1313. noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
  1314. caches in the slab allocator. Saves per-node memory,
  1315. but will impact performance.
  1316. noalign [KNL,ARM]
  1317. noapic [SMP,APIC] Tells the kernel to not make use of any
  1318. IOAPICs that may be present in the system.
  1319. nobats [PPC] Do not use BATs for mapping kernel lowmem
  1320. on "Classic" PPC cores.
  1321. nocache [ARM]
  1322. noclflush [BUGS=X86] Don't use the CLFLUSH instruction
  1323. nodelayacct [KNL] Disable per-task delay accounting
  1324. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  1325. nodsp [SH] Disable hardware DSP at boot time.
  1326. noefi [X86] Disable EFI runtime services support.
  1327. noexec [IA-64]
  1328. noexec [X86]
  1329. On X86-32 available only on PAE configured kernels.
  1330. noexec=on: enable non-executable mappings (default)
  1331. noexec=off: disable non-executable mappings
  1332. noexec32 [X86-64]
  1333. This affects only 32-bit executables.
  1334. noexec32=on: enable non-executable mappings (default)
  1335. read doesn't imply executable mappings
  1336. noexec32=off: disable non-executable mappings
  1337. read implies executable mappings
  1338. nofpu [SH] Disable hardware FPU at boot time.
  1339. nofxsr [BUGS=X86-32] Disables x86 floating point extended
  1340. register save and restore. The kernel will only save
  1341. legacy floating-point registers on task switch.
  1342. noxsave [BUGS=X86] Disables x86 extended register state save
  1343. and restore using xsave. The kernel will fallback to
  1344. enabling legacy floating-point and sse state.
  1345. nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
  1346. wfi(ARM) instruction doesn't work correctly and not to
  1347. use it. This is also useful when using JTAG debugger.
  1348. no-hlt [BUGS=X86-32] Tells the kernel that the hlt
  1349. instruction doesn't work correctly and not to
  1350. use it.
  1351. no_file_caps Tells the kernel not to honor file capabilities. The
  1352. only way then for a file to be executed with privilege
  1353. is to be setuid root or executed by root.
  1354. nohalt [IA-64] Tells the kernel not to use the power saving
  1355. function PAL_HALT_LIGHT when idle. This increases
  1356. power-consumption. On the positive side, it reduces
  1357. interrupt wake-up latency, which may improve performance
  1358. in certain environments such as networked servers or
  1359. real-time systems.
  1360. nohz= [KNL] Boottime enable/disable dynamic ticks
  1361. Valid arguments: on, off
  1362. Default: on
  1363. noiotrap [SH] Disables trapped I/O port accesses.
  1364. noirqdebug [X86-32] Disables the code which attempts to detect and
  1365. disable unhandled interrupt sources.
  1366. no_timer_check [X86,APIC] Disables the code which tests for
  1367. broken timer IRQ sources.
  1368. noisapnp [ISAPNP] Disables ISA PnP code.
  1369. noinitrd [RAM] Tells the kernel not to load any configured
  1370. initial RAM disk.
  1371. nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
  1372. remapping.
  1373. nointroute [IA-64]
  1374. nojitter [IA64] Disables jitter checking for ITC timers.
  1375. nolapic [X86-32,APIC] Do not enable or use the local APIC.
  1376. nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
  1377. noltlbs [PPC] Do not use large page/tlb entries for kernel
  1378. lowmem mapping on PPC40x.
  1379. nomca [IA-64] Disable machine check abort handling
  1380. nomce [X86-32] Machine Check Exception
  1381. nomfgpt [X86-32] Disable Multi-Function General Purpose
  1382. Timer usage (for AMD Geode machines).
  1383. norandmaps Don't use address space randomization. Equivalent to
  1384. echo 0 > /proc/sys/kernel/randomize_va_space
  1385. noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
  1386. noreplace-smp [X86-32,SMP] Don't replace SMP instructions
  1387. with UP alternatives
  1388. noresidual [PPC] Don't use residual data on PReP machines.
  1389. noresume [SWSUSP] Disables resume and restores original swap
  1390. space.
  1391. no-scroll [VGA] Disables scrollback.
  1392. This is required for the Braillex ib80-piezo Braille
  1393. reader made by F.H. Papenmeier (Germany).
  1394. nosbagart [IA-64]
  1395. nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
  1396. nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
  1397. and disable the IO APIC. legacy for "maxcpus=0".
  1398. nosoftlockup [KNL] Disable the soft-lockup detector.
  1399. noswapaccount [KNL] Disable accounting of swap in memory resource
  1400. controller. (See Documentation/cgroups/memory.txt)
  1401. nosync [HW,M68K] Disables sync negotiation for all devices.
  1402. notsc [BUGS=X86-32] Disable Time Stamp Counter
  1403. nousb [USB] Disable the USB subsystem
  1404. nowb [ARM]
  1405. nox2apic [X86-64,APIC] Do not enable x2APIC mode.
  1406. nptcg= [IA64] Override max number of concurrent global TLB
  1407. purges which is reported from either PAL_VM_SUMMARY or
  1408. SAL PALO.
  1409. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  1410. numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
  1411. one of ['zone', 'node', 'default'] can be specified
  1412. This can be set from sysctl after boot.
  1413. See Documentation/sysctl/vm.txt for details.
  1414. ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
  1415. See Documentation/debugging-via-ohci1394.txt for more
  1416. info.
  1417. olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
  1418. Rather than timing out after 20 ms if an EC
  1419. command is not properly ACKed, override the length
  1420. of the timeout. We have interrupts disabled while
  1421. waiting for the ACK, so if this is set too high
  1422. interrupts *may* be lost!
  1423. omap_mux= [OMAP] Override bootloader pin multiplexing.
  1424. Format: <mux_mode0.mode_name=value>...
  1425. For example, to override I2C bus2:
  1426. omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
  1427. opl3= [HW,OSS]
  1428. Format: <io>
  1429. oprofile.timer= [HW]
  1430. Use timer interrupt instead of performance counters
  1431. oprofile.cpu_type= Force an oprofile cpu type
  1432. This might be useful if you have an older oprofile
  1433. userland or if you want common events.
  1434. Format: { arch_perfmon }
  1435. arch_perfmon: [X86] Force use of architectural
  1436. perfmon on Intel CPUs instead of the
  1437. CPU specific event set.
  1438. osst= [HW,SCSI] SCSI Tape Driver
  1439. Format: <buffer_size>,<write_threshold>
  1440. See also Documentation/scsi/st.txt.
  1441. panic= [KNL] Kernel behaviour on panic
  1442. Format: <timeout>
  1443. parkbd.port= [HW] Parallel port number the keyboard adapter is
  1444. connected to, default is 0.
  1445. Format: <parport#>
  1446. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  1447. 0 for XT, 1 for AT (default is AT).
  1448. Format: <mode>
  1449. parport= [HW,PPT] Specify parallel ports. 0 disables.
  1450. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  1451. Use 'auto' to force the driver to use any
  1452. IRQ/DMA settings detected (the default is to
  1453. ignore detected IRQ/DMA settings because of
  1454. possible conflicts). You can specify the base
  1455. address, IRQ, and DMA settings; IRQ and DMA
  1456. should be numbers, or 'auto' (for using detected
  1457. settings on that particular port), or 'nofifo'
  1458. (to avoid using a FIFO even if it is detected).
  1459. Parallel ports are assigned in the order they
  1460. are specified on the command line, starting
  1461. with parport0.
  1462. parport_init_mode= [HW,PPT]
  1463. Configure VIA parallel port to operate in
  1464. a specific mode. This is necessary on Pegasos
  1465. computer where firmware has no options for setting
  1466. up parallel port mode and sets it to spp.
  1467. Currently this function knows 686a and 8231 chips.
  1468. Format: [spp|ps2|epp|ecp|ecpepp]
  1469. pas2= [HW,OSS] Format:
  1470. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  1471. pas16= [HW,SCSI]
  1472. See header of drivers/scsi/pas16.c.
  1473. pause_on_oops=
  1474. Halt all CPUs after the first oops has been printed for
  1475. the specified number of seconds. This is to be used if
  1476. your oopses keep scrolling off the screen.
  1477. pcbit= [HW,ISDN]
  1478. pcd. [PARIDE]
  1479. See header of drivers/block/paride/pcd.c.
  1480. See also Documentation/blockdev/paride.txt.
  1481. pci=option[,option...] [PCI] various PCI subsystem options:
  1482. earlydump [X86] dump PCI config space before the kernel
  1483. changes anything
  1484. off [X86] don't probe for the PCI bus
  1485. bios [X86-32] force use of PCI BIOS, don't access
  1486. the hardware directly. Use this if your machine
  1487. has a non-standard PCI host bridge.
  1488. nobios [X86-32] disallow use of PCI BIOS, only direct
  1489. hardware access methods are allowed. Use this
  1490. if you experience crashes upon bootup and you
  1491. suspect they are caused by the BIOS.
  1492. conf1 [X86] Force use of PCI Configuration
  1493. Mechanism 1.
  1494. conf2 [X86] Force use of PCI Configuration
  1495. Mechanism 2.
  1496. noaer [PCIE] If the PCIEAER kernel config parameter is
  1497. enabled, this kernel boot option can be used to
  1498. disable the use of PCIE advanced error reporting.
  1499. nodomains [PCI] Disable support for multiple PCI
  1500. root domains (aka PCI segments, in ACPI-speak).
  1501. nommconf [X86] Disable use of MMCONFIG for PCI
  1502. Configuration
  1503. check_enable_amd_mmconf [X86] check for and enable
  1504. properly configured MMIO access to PCI
  1505. config space on AMD family 10h CPU
  1506. nomsi [MSI] If the PCI_MSI kernel config parameter is
  1507. enabled, this kernel boot option can be used to
  1508. disable the use of MSI interrupts system-wide.
  1509. noioapicquirk [APIC] Disable all boot interrupt quirks.
  1510. Safety option to keep boot IRQs enabled. This
  1511. should never be necessary.
  1512. ioapicreroute [APIC] Enable rerouting of boot IRQs to the
  1513. primary IO-APIC for bridges that cannot disable
  1514. boot IRQs. This fixes a source of spurious IRQs
  1515. when the system masks IRQs.
  1516. noioapicreroute [APIC] Disable workaround that uses the
  1517. boot IRQ equivalent of an IRQ that connects to
  1518. a chipset where boot IRQs cannot be disabled.
  1519. The opposite of ioapicreroute.
  1520. biosirq [X86-32] Use PCI BIOS calls to get the interrupt
  1521. routing table. These calls are known to be buggy
  1522. on several machines and they hang the machine
  1523. when used, but on other computers it's the only
  1524. way to get the interrupt routing table. Try
  1525. this option if the kernel is unable to allocate
  1526. IRQs or discover secondary PCI buses on your
  1527. motherboard.
  1528. rom [X86] Assign address space to expansion ROMs.
  1529. Use with caution as certain devices share
  1530. address decoders between ROMs and other
  1531. resources.
  1532. norom [X86] Do not assign address space to
  1533. expansion ROMs that do not already have
  1534. BIOS assigned address ranges.
  1535. irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
  1536. assigned automatically to PCI devices. You can
  1537. make the kernel exclude IRQs of your ISA cards
  1538. this way.
  1539. pirqaddr=0xAAAAA [X86] Specify the physical address
  1540. of the PIRQ table (normally generated
  1541. by the BIOS) if it is outside the
  1542. F0000h-100000h range.
  1543. lastbus=N [X86] Scan all buses thru bus #N. Can be
  1544. useful if the kernel is unable to find your
  1545. secondary buses and you want to tell it
  1546. explicitly which ones they are.
  1547. assign-busses [X86] Always assign all PCI bus
  1548. numbers ourselves, overriding
  1549. whatever the firmware may have done.
  1550. usepirqmask [X86] Honor the possible IRQ mask stored
  1551. in the BIOS $PIR table. This is needed on
  1552. some systems with broken BIOSes, notably
  1553. some HP Pavilion N5400 and Omnibook XE3
  1554. notebooks. This will have no effect if ACPI
  1555. IRQ routing is enabled.
  1556. noacpi [X86] Do not use ACPI for IRQ routing
  1557. or for PCI scanning.
  1558. use_crs [X86] Use _CRS for PCI resource
  1559. allocation.
  1560. routeirq Do IRQ routing for all PCI devices.
  1561. This is normally done in pci_enable_device(),
  1562. so this option is a temporary workaround
  1563. for broken drivers that don't call it.
  1564. skip_isa_align [X86] do not align io start addr, so can
  1565. handle more pci cards
  1566. firmware [ARM] Do not re-enumerate the bus but instead
  1567. just use the configuration from the
  1568. bootloader. This is currently used on
  1569. IXP2000 systems where the bus has to be
  1570. configured a certain way for adjunct CPUs.
  1571. noearly [X86] Don't do any early type 1 scanning.
  1572. This might help on some broken boards which
  1573. machine check when some devices' config space
  1574. is read. But various workarounds are disabled
  1575. and some IOMMU drivers will not work.
  1576. bfsort Sort PCI devices into breadth-first order.
  1577. This sorting is done to get a device
  1578. order compatible with older (<= 2.4) kernels.
  1579. nobfsort Don't sort PCI devices into breadth-first order.
  1580. cbiosize=nn[KMG] The fixed amount of bus space which is
  1581. reserved for the CardBus bridge's IO window.
  1582. The default value is 256 bytes.
  1583. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1584. reserved for the CardBus bridge's memory
  1585. window. The default value is 64 megabytes.
  1586. resource_alignment=
  1587. Format:
  1588. [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
  1589. Specifies alignment and device to reassign
  1590. aligned memory resources.
  1591. If <order of align> is not specified,
  1592. PAGE_SIZE is used as alignment.
  1593. PCI-PCI bridge can be specified, if resource
  1594. windows need to be expanded.
  1595. ecrc= Enable/disable PCIe ECRC (transaction layer
  1596. end-to-end CRC checking).
  1597. bios: Use BIOS/firmware settings. This is the
  1598. the default.
  1599. off: Turn ECRC off
  1600. on: Turn ECRC on.
  1601. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
  1602. Management.
  1603. off Disable ASPM.
  1604. force Enable ASPM even on devices that claim not to support it.
  1605. WARNING: Forcing ASPM on may cause system lockups.
  1606. pcmv= [HW,PCMCIA] BadgePAD 4
  1607. pd. [PARIDE]
  1608. See Documentation/blockdev/paride.txt.
  1609. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1610. boot time.
  1611. Format: { 0 | 1 }
  1612. See arch/parisc/kernel/pdc_chassis.c
  1613. percpu_alloc= Select which percpu first chunk allocator to use.
  1614. Currently supported values are "embed" and "page".
  1615. Archs may support subset or none of the selections.
  1616. See comments in mm/percpu.c for details on each
  1617. allocator. This parameter is primarily for debugging
  1618. and performance comparison.
  1619. pf. [PARIDE]
  1620. See Documentation/blockdev/paride.txt.
  1621. pg. [PARIDE]
  1622. See Documentation/blockdev/paride.txt.
  1623. pirq= [SMP,APIC] Manual mp-table setup
  1624. See Documentation/x86/i386/IO-APIC.txt.
  1625. plip= [PPT,NET] Parallel port network link
  1626. Format: { parport<nr> | timid | 0 }
  1627. See also Documentation/parport.txt.
  1628. pmtmr= [X86] Manual setup of pmtmr I/O Port.
  1629. Override pmtimer IOPort with a hex value.
  1630. e.g. pmtmr=0x508
  1631. pnp.debug [PNP]
  1632. Enable PNP debug messages. This depends on the
  1633. CONFIG_PNP_DEBUG_MESSAGES option.
  1634. pnpacpi= [ACPI]
  1635. { off }
  1636. pnpbios= [ISAPNP]
  1637. { on | off | curr | res | no-curr | no-res }
  1638. pnp_reserve_irq=
  1639. [ISAPNP] Exclude IRQs for the autoconfiguration
  1640. pnp_reserve_dma=
  1641. [ISAPNP] Exclude DMAs for the autoconfiguration
  1642. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1643. Ranges are in pairs (I/O port base and size).
  1644. pnp_reserve_mem=
  1645. [ISAPNP] Exclude memory regions for the
  1646. autoconfiguration.
  1647. Ranges are in pairs (memory base and size).
  1648. ports= [IP_VS_FTP] IPVS ftp helper module
  1649. Default is 21.
  1650. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  1651. may be specified.
  1652. Format: <port>,<port>....
  1653. print-fatal-signals=
  1654. [KNL] debug: print fatal signals
  1655. If enabled, warn about various signal handling
  1656. related application anomalies: too many signals,
  1657. too many POSIX.1 timers, fatal signals causing a
  1658. coredump - etc.
  1659. If you hit the warning due to signal overflow,
  1660. you might want to try "ulimit -i unlimited".
  1661. default: off.
  1662. printk.time= Show timing data prefixed to each printk message line
  1663. Format: <bool> (1/Y/y=enable, 0/N/n=disable)
  1664. processor.max_cstate= [HW,ACPI]
  1665. Limit processor to maximum C-state
  1666. max_cstate=9 overrides any DMI blacklist limit.
  1667. processor.nocst [HW,ACPI]
  1668. Ignore the _CST method to determine C-states,
  1669. instead using the legacy FADT method
  1670. profile= [KNL] Enable kernel profiling via /proc/profile
  1671. Format: [schedule,]<number>
  1672. Param: "schedule" - profile schedule points.
  1673. Param: <number> - step/bucket size as a power of 2 for
  1674. statistical time based profiling.
  1675. Param: "sleep" - profile D-state sleeping (millisecs).
  1676. Requires CONFIG_SCHEDSTATS
  1677. Param: "kvm" - profile VM exits.
  1678. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1679. before loading.
  1680. See Documentation/blockdev/ramdisk.txt.
  1681. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1682. probe for; one of (bare|imps|exps|lifebook|any).
  1683. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1684. per second.
  1685. psmouse.resetafter= [HW,MOUSE]
  1686. Try to reset the device after so many bad packets
  1687. (0 = never).
  1688. psmouse.resolution=
  1689. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1690. psmouse.smartscroll=
  1691. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1692. 0 = disabled, 1 = enabled (default).
  1693. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1694. Format:
  1695. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1696. pt. [PARIDE]
  1697. See Documentation/blockdev/paride.txt.
  1698. pty.legacy_count=
  1699. [KNL] Number of legacy pty's. Overwrites compiled-in
  1700. default number.
  1701. quiet [KNL] Disable most log messages
  1702. r128= [HW,DRM]
  1703. raid= [HW,RAID]
  1704. See Documentation/md.txt.
  1705. ramdisk_blocksize= [RAM]
  1706. See Documentation/blockdev/ramdisk.txt.
  1707. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1708. See Documentation/blockdev/ramdisk.txt.
  1709. rcupdate.blimit= [KNL,BOOT]
  1710. Set maximum number of finished RCU callbacks to process
  1711. in one batch.
  1712. rcupdate.qhimark= [KNL,BOOT]
  1713. Set threshold of queued
  1714. RCU callbacks over which batch limiting is disabled.
  1715. rcupdate.qlowmark= [KNL,BOOT]
  1716. Set threshold of queued RCU callbacks below which
  1717. batch limiting is re-enabled.
  1718. rdinit= [KNL]
  1719. Format: <full_path>
  1720. Run specified binary instead of /init from the ramdisk,
  1721. used for early userspace startup. See initrd.
  1722. reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1723. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1724. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1725. relax_domain_level=
  1726. [KNL, SMP] Set scheduler's default relax_domain_level.
  1727. See Documentation/cgroups/cpusets.txt.
  1728. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1729. reservetop= [X86-32]
  1730. Format: nn[KMG]
  1731. Reserves a hole at the top of the kernel virtual
  1732. address space.
  1733. reset_devices [KNL] Force drivers to reset the underlying device
  1734. during initialization.
  1735. resume= [SWSUSP]
  1736. Specify the partition device for software suspend
  1737. resume_offset= [SWSUSP]
  1738. Specify the offset from the beginning of the partition
  1739. given by "resume=" at which the swap header is located,
  1740. in <PAGE_SIZE> units (needed only for swap files).
  1741. See Documentation/power/swsusp-and-swap-files.txt
  1742. retain_initrd [RAM] Keep initrd memory after extraction
  1743. rhash_entries= [KNL,NET]
  1744. Set number of hash buckets for route cache
  1745. riscom8= [HW,SERIAL]
  1746. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1747. ro [KNL] Mount root device read-only on boot
  1748. root= [KNL] Root filesystem
  1749. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1750. mount the root filesystem
  1751. rootflags= [KNL] Set root filesystem mount option string
  1752. rootfstype= [KNL] Set root filesystem type
  1753. rootwait [KNL] Wait (indefinitely) for root device to show up.
  1754. Useful for devices that are detected asynchronously
  1755. (e.g. USB and MMC devices).
  1756. rw [KNL] Mount root device read-write on boot
  1757. S [KNL] Run init in single mode
  1758. sa1100ir [NET]
  1759. See drivers/net/irda/sa1100_ir.c.
  1760. sbni= [NET] Granch SBNI12 leased line adapter
  1761. sched_debug [KNL] Enables verbose scheduler debug messages.
  1762. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1763. Format: <io>[,<timeout>[,<isapnp>]]
  1764. scsi_debug_*= [SCSI]
  1765. See drivers/scsi/scsi_debug.c.
  1766. scsi_default_dev_flags=
  1767. [SCSI] SCSI default device flags
  1768. Format: <integer>
  1769. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1770. Format: <vendor>:<model>:<flags>
  1771. (flags are integer value)
  1772. scsi_logging_level= [SCSI] a bit mask of logging levels
  1773. See drivers/scsi/scsi_logging.h for bits. Also
  1774. settable via sysctl at dev.scsi.logging_level
  1775. (/proc/sys/dev/scsi/logging_level).
  1776. There is also a nice 'scsi_logging_level' script in the
  1777. S390-tools package, available for download at
  1778. http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
  1779. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1780. discovered. async scans them in kernel threads,
  1781. allowing boot to proceed. none ignores them, expecting
  1782. user space to do the scan.
  1783. security= [SECURITY] Choose a security module to enable at boot.
  1784. If this boot parameter is not specified, only the first
  1785. security module asking for security registration will be
  1786. loaded. An invalid security module name will be treated
  1787. as if no module has been chosen.
  1788. selinux= [SELINUX] Disable or enable SELinux at boot time.
  1789. Format: { "0" | "1" }
  1790. See security/selinux/Kconfig help text.
  1791. 0 -- disable.
  1792. 1 -- enable.
  1793. Default value is set via kernel config option.
  1794. If enabled at boot time, /selinux/disable can be used
  1795. later to disable prior to initial policy load.
  1796. serialnumber [BUGS=X86-32]
  1797. shapers= [NET]
  1798. Maximal number of shapers.
  1799. show_msr= [x86] show boot-time MSR settings
  1800. Format: { <integer> }
  1801. Show boot-time (BIOS-initialized) MSR settings.
  1802. The parameter means the number of CPUs to show,
  1803. for example 1 means boot CPU only.
  1804. sim710= [SCSI,HW]
  1805. See header of drivers/scsi/sim710.c.
  1806. simeth= [IA-64]
  1807. simscsi=
  1808. slram= [HW,MTD]
  1809. slub_debug[=options[,slabs]] [MM, SLUB]
  1810. Enabling slub_debug allows one to determine the
  1811. culprit if slab objects become corrupted. Enabling
  1812. slub_debug can create guard zones around objects and
  1813. may poison objects when not in use. Also tracks the
  1814. last alloc / free. For more information see
  1815. Documentation/vm/slub.txt.
  1816. slub_max_order= [MM, SLUB]
  1817. Determines the maximum allowed order for slabs.
  1818. A high setting may cause OOMs due to memory
  1819. fragmentation. For more information see
  1820. Documentation/vm/slub.txt.
  1821. slub_min_objects= [MM, SLUB]
  1822. The minimum number of objects per slab. SLUB will
  1823. increase the slab order up to slub_max_order to
  1824. generate a sufficiently large slab able to contain
  1825. the number of objects indicated. The higher the number
  1826. of objects the smaller the overhead of tracking slabs
  1827. and the less frequently locks need to be acquired.
  1828. For more information see Documentation/vm/slub.txt.
  1829. slub_min_order= [MM, SLUB]
  1830. Determines the mininum page order for slabs. Must be
  1831. lower than slub_max_order.
  1832. For more information see Documentation/vm/slub.txt.
  1833. slub_nomerge [MM, SLUB]
  1834. Disable merging of slabs with similar size. May be
  1835. necessary if there is some reason to distinguish
  1836. allocs to different slabs. Debug options disable
  1837. merging on their own.
  1838. For more information see Documentation/vm/slub.txt.
  1839. smart2= [HW]
  1840. Format: <io1>[,<io2>[,...,<io8>]]
  1841. smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
  1842. attempt to substitute SMP alternatives once at boot.
  1843. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1844. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1845. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1846. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1847. smsc-ircc2.ircc_irq= [HW] IRQ line
  1848. smsc-ircc2.ircc_dma= [HW] DMA channel
  1849. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1850. 0: Toshiba Satellite 1800 (GP data pin select)
  1851. 1: Fast pin select (default)
  1852. 2: ATC IRMode
  1853. snd-ad1816a= [HW,ALSA]
  1854. snd-ad1848= [HW,ALSA]
  1855. snd-ali5451= [HW,ALSA]
  1856. snd-als100= [HW,ALSA]
  1857. snd-als4000= [HW,ALSA]
  1858. snd-azt2320= [HW,ALSA]
  1859. snd-cmi8330= [HW,ALSA]
  1860. snd-cmipci= [HW,ALSA]
  1861. snd-cs4231= [HW,ALSA]
  1862. snd-cs4232= [HW,ALSA]
  1863. snd-cs4236= [HW,ALSA]
  1864. snd-cs4281= [HW,ALSA]
  1865. snd-cs46xx= [HW,ALSA]
  1866. snd-dt019x= [HW,ALSA]
  1867. snd-dummy= [HW,ALSA]
  1868. snd-emu10k1= [HW,ALSA]
  1869. snd-ens1370= [HW,ALSA]
  1870. snd-ens1371= [HW,ALSA]
  1871. snd-es968= [HW,ALSA]
  1872. snd-es1688= [HW,ALSA]
  1873. snd-es18xx= [HW,ALSA]
  1874. snd-es1938= [HW,ALSA]
  1875. snd-es1968= [HW,ALSA]
  1876. snd-fm801= [HW,ALSA]
  1877. snd-gusclassic= [HW,ALSA]
  1878. snd-gusextreme= [HW,ALSA]
  1879. snd-gusmax= [HW,ALSA]
  1880. snd-hdsp= [HW,ALSA]
  1881. snd-ice1712= [HW,ALSA]
  1882. snd-intel8x0= [HW,ALSA]
  1883. snd-interwave= [HW,ALSA]
  1884. snd-interwave-stb=
  1885. [HW,ALSA]
  1886. snd-korg1212= [HW,ALSA]
  1887. snd-maestro3= [HW,ALSA]
  1888. snd-mpu401= [HW,ALSA]
  1889. snd-mtpav= [HW,ALSA]
  1890. snd-nm256= [HW,ALSA]
  1891. snd-opl3sa2= [HW,ALSA]
  1892. snd-opti92x-ad1848=
  1893. [HW,ALSA]
  1894. snd-opti92x-cs4231=
  1895. [HW,ALSA]
  1896. snd-opti93x= [HW,ALSA]
  1897. snd-pmac= [HW,ALSA]
  1898. snd-rme32= [HW,ALSA]
  1899. snd-rme96= [HW,ALSA]
  1900. snd-rme9652= [HW,ALSA]
  1901. snd-sb8= [HW,ALSA]
  1902. snd-sb16= [HW,ALSA]
  1903. snd-sbawe= [HW,ALSA]
  1904. snd-serial= [HW,ALSA]
  1905. snd-sgalaxy= [HW,ALSA]
  1906. snd-sonicvibes= [HW,ALSA]
  1907. snd-sun-amd7930=
  1908. [HW,ALSA]
  1909. snd-sun-cs4231= [HW,ALSA]
  1910. snd-trident= [HW,ALSA]
  1911. snd-usb-audio= [HW,ALSA,USB]
  1912. snd-via82xx= [HW,ALSA]
  1913. snd-virmidi= [HW,ALSA]
  1914. snd-wavefront= [HW,ALSA]
  1915. snd-ymfpci= [HW,ALSA]
  1916. softlockup_panic=
  1917. [KNL] Should the soft-lockup detector generate panics.
  1918. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1919. See Documentation/sonypi.txt
  1920. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1921. See Documentation/serial/specialix.txt.
  1922. spia_io_base= [HW,MTD]
  1923. spia_fio_base=
  1924. spia_pedr=
  1925. spia_peddr=
  1926. sscape= [HW,OSS]
  1927. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1928. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1929. See Documentation/scsi/st.txt.
  1930. stacktrace [FTRACE]
  1931. Enabled the stack tracer on boot up.
  1932. sti= [PARISC,HW]
  1933. Format: <num>
  1934. Set the STI (builtin display/keyboard on the HP-PARISC
  1935. machines) console (graphic card) which should be used
  1936. as the initial boot-console.
  1937. See also comment in drivers/video/console/sticore.c.
  1938. sti_font= [HW]
  1939. See comment in drivers/video/console/sticore.c.
  1940. stifb= [HW]
  1941. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1942. sunrpc.min_resvport=
  1943. sunrpc.max_resvport=
  1944. [NFS,SUNRPC]
  1945. SunRPC servers often require that client requests
  1946. originate from a privileged port (i.e. a port in the
  1947. range 0 < portnr < 1024).
  1948. An administrator who wishes to reserve some of these
  1949. ports for other uses may adjust the range that the
  1950. kernel's sunrpc client considers to be privileged
  1951. using these two parameters to set the minimum and
  1952. maximum port values.
  1953. sunrpc.pool_mode=
  1954. [NFS]
  1955. Control how the NFS server code allocates CPUs to
  1956. service thread pools. Depending on how many NICs
  1957. you have and where their interrupts are bound, this
  1958. option will affect which CPUs will do NFS serving.
  1959. Note: this parameter cannot be changed while the
  1960. NFS server is running.
  1961. auto the server chooses an appropriate mode
  1962. automatically using heuristics
  1963. global a single global pool contains all CPUs
  1964. percpu one pool for each CPU
  1965. pernode one pool for each NUMA node (equivalent
  1966. to global on non-NUMA machines)
  1967. sunrpc.tcp_slot_table_entries=
  1968. sunrpc.udp_slot_table_entries=
  1969. [NFS,SUNRPC]
  1970. Sets the upper limit on the number of simultaneous
  1971. RPC calls that can be sent from the client to a
  1972. server. Increasing these values may allow you to
  1973. improve throughput, but will also increase the
  1974. amount of memory reserved for use by the client.
  1975. swiotlb= [IA-64] Number of I/O TLB slabs
  1976. switches= [HW,M68k]
  1977. sym53c416= [HW,SCSI]
  1978. See header of drivers/scsi/sym53c416.c.
  1979. sysrq_always_enabled
  1980. [KNL]
  1981. Ignore sysrq setting - this boot parameter will
  1982. neutralize any effect of /proc/sys/kernel/sysrq.
  1983. Useful for debugging.
  1984. t128= [HW,SCSI]
  1985. See header of drivers/scsi/t128.c.
  1986. tdfx= [HW,DRM]
  1987. test_suspend= [SUSPEND]
  1988. Specify "mem" (for Suspend-to-RAM) or "standby" (for
  1989. standby suspend) as the system sleep state to briefly
  1990. enter during system startup. The system is woken from
  1991. this state using a wakeup-capable RTC alarm.
  1992. thash_entries= [KNL,NET]
  1993. Set number of hash buckets for TCP connection
  1994. thermal.act= [HW,ACPI]
  1995. -1: disable all active trip points in all thermal zones
  1996. <degrees C>: override all lowest active trip points
  1997. thermal.crt= [HW,ACPI]
  1998. -1: disable all critical trip points in all thermal zones
  1999. <degrees C>: override all critical trip points
  2000. thermal.nocrt= [HW,ACPI]
  2001. Set to disable actions on ACPI thermal zone
  2002. critical and hot trip points.
  2003. thermal.off= [HW,ACPI]
  2004. 1: disable ACPI thermal control
  2005. thermal.psv= [HW,ACPI]
  2006. -1: disable all passive trip points
  2007. <degrees C>: override all passive trip points to this
  2008. value
  2009. thermal.tzp= [HW,ACPI]
  2010. Specify global default ACPI thermal zone polling rate
  2011. <deci-seconds>: poll all this frequency
  2012. 0: no polling (default)
  2013. tmscsim= [HW,SCSI]
  2014. See comment before function dc390_setup() in
  2015. drivers/scsi/tmscsim.c.
  2016. topology= [S390]
  2017. Format: {off | on}
  2018. Specify if the kernel should make use of the cpu
  2019. topology informations if the hardware supports these.
  2020. The scheduler will make use of these informations and
  2021. e.g. base its process migration decisions on it.
  2022. Default is off.
  2023. tp720= [HW,PS2]
  2024. trace_buf_size=nn[KMG]
  2025. [FTRACE] will set tracing buffer size.
  2026. trace_event=[event-list]
  2027. [FTRACE] Set and start specified trace events in order
  2028. to facilitate early boot debugging.
  2029. See also Documentation/trace/events.txt
  2030. trix= [HW,OSS] MediaTrix AudioTrix Pro
  2031. Format:
  2032. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  2033. tsc= Disable clocksource-must-verify flag for TSC.
  2034. Format: <string>
  2035. [x86] reliable: mark tsc clocksource as reliable, this
  2036. disables clocksource verification at runtime.
  2037. Used to enable high-resolution timer mode on older
  2038. hardware, and in virtualized environment.
  2039. turbografx.map[2|3]= [HW,JOY]
  2040. TurboGraFX parallel port interface
  2041. Format:
  2042. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  2043. See also Documentation/input/joystick-parport.txt
  2044. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  2045. See header of drivers/scsi/u14-34f.c.
  2046. uart401= [HW,OSS]
  2047. Format: <io>,<irq>
  2048. uart6850= [HW,OSS]
  2049. Format: <io>,<irq>
  2050. uhash_entries= [KNL,NET]
  2051. Set number of hash buckets for UDP/UDP-Lite connections
  2052. uhci-hcd.ignore_oc=
  2053. [USB] Ignore overcurrent events (default N).
  2054. Some badly-designed motherboards generate lots of
  2055. bogus events, for ports that aren't wired to
  2056. anything. Set this parameter to avoid log spamming.
  2057. Note that genuine overcurrent events won't be
  2058. reported either.
  2059. unknown_nmi_panic
  2060. [X86]
  2061. Set unknown_nmi_panic=1 early on boot.
  2062. usbcore.autosuspend=
  2063. [USB] The autosuspend time delay (in seconds) used
  2064. for newly-detected USB devices (default 2). This
  2065. is the time required before an idle device will be
  2066. autosuspended. Devices for which the delay is set
  2067. to a negative value won't be autosuspended at all.
  2068. usbcore.usbfs_snoop=
  2069. [USB] Set to log all usbfs traffic (default 0 = off).
  2070. usbcore.blinkenlights=
  2071. [USB] Set to cycle leds on hubs (default 0 = off).
  2072. usbcore.old_scheme_first=
  2073. [USB] Start with the old device initialization
  2074. scheme (default 0 = off).
  2075. usbcore.use_both_schemes=
  2076. [USB] Try the other device initialization scheme
  2077. if the first one fails (default 1 = enabled).
  2078. usbcore.initial_descriptor_timeout=
  2079. [USB] Specifies timeout for the initial 64-byte
  2080. USB_REQ_GET_DESCRIPTOR request in milliseconds
  2081. (default 5000 = 5.0 seconds).
  2082. usbhid.mousepoll=
  2083. [USBHID] The interval which mice are to be polled at.
  2084. usb-storage.delay_use=
  2085. [UMS] The delay in seconds before a new device is
  2086. scanned for Logical Units (default 5).
  2087. usb-storage.quirks=
  2088. [UMS] A list of quirks entries to supplement or
  2089. override the built-in unusual_devs list. List
  2090. entries are separated by commas. Each entry has
  2091. the form VID:PID:Flags where VID and PID are Vendor
  2092. and Product ID values (4-digit hex numbers) and
  2093. Flags is a set of characters, each corresponding
  2094. to a common usb-storage quirk flag as follows:
  2095. a = SANE_SENSE (collect more than 18 bytes
  2096. of sense data);
  2097. b = BAD_SENSE (don't collect more than 18
  2098. bytes of sense data);
  2099. c = FIX_CAPACITY (decrease the reported
  2100. device capacity by one sector);
  2101. h = CAPACITY_HEURISTICS (decrease the
  2102. reported device capacity by one
  2103. sector if the number is odd);
  2104. i = IGNORE_DEVICE (don't bind to this
  2105. device);
  2106. l = NOT_LOCKABLE (don't try to lock and
  2107. unlock ejectable media);
  2108. m = MAX_SECTORS_64 (don't transfer more
  2109. than 64 sectors = 32 KB at a time);
  2110. o = CAPACITY_OK (accept the capacity
  2111. reported by the device);
  2112. r = IGNORE_RESIDUE (the device reports
  2113. bogus residue values);
  2114. s = SINGLE_LUN (the device has only one
  2115. Logical Unit);
  2116. w = NO_WP_DETECT (don't test whether the
  2117. medium is write-protected).
  2118. Example: quirks=0419:aaf5:rl,0421:0433:rc
  2119. vdso= [X86,SH]
  2120. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  2121. vdso=1: enable VDSO (default)
  2122. vdso=0: disable VDSO mapping
  2123. vdso32= [X86]
  2124. vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
  2125. vdso32=1: enable 32-bit VDSO (default)
  2126. vdso32=0: disable 32-bit VDSO mapping
  2127. vector= [IA-64,SMP]
  2128. vector=percpu: enable percpu vector domain
  2129. video= [FB] Frame buffer configuration
  2130. See Documentation/fb/modedb.txt.
  2131. vga= [BOOT,X86-32] Select a particular video mode
  2132. See Documentation/x86/boot.txt and
  2133. Documentation/svga.txt.
  2134. Use vga=ask for menu.
  2135. This is actually a boot loader parameter; the value is
  2136. passed to the kernel using a special protocol.
  2137. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  2138. size of <nn>. This can be used to increase the
  2139. minimum size (128MB on x86). It can also be used to
  2140. decrease the size and leave more room for directly
  2141. mapped kernel RAM.
  2142. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  2143. Format: <command>
  2144. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  2145. Format: <command>
  2146. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  2147. Format: <command>
  2148. vt.cur_default= [VT] Default cursor shape.
  2149. Format: 0xCCBBAA, where AA, BB, and CC are the same as
  2150. the parameters of the <Esc>[?A;B;Cc escape sequence;
  2151. see VGA-softcursor.txt. Default: 2 = underline.
  2152. vt.default_blu= [VT]
  2153. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  2154. Change the default blue palette of the console.
  2155. This is a 16-member array composed of values
  2156. ranging from 0-255.
  2157. vt.default_grn= [VT]
  2158. Format: <green0>,<green1>,<green2>,...,<green15>
  2159. Change the default green palette of the console.
  2160. This is a 16-member array composed of values
  2161. ranging from 0-255.
  2162. vt.default_red= [VT]
  2163. Format: <red0>,<red1>,<red2>,...,<red15>
  2164. Change the default red palette of the console.
  2165. This is a 16-member array composed of values
  2166. ranging from 0-255.
  2167. vt.default_utf8=
  2168. [VT]
  2169. Format=<0|1>
  2170. Set system-wide default UTF-8 mode for all tty's.
  2171. Default is 1, i.e. UTF-8 mode is enabled for all
  2172. newly opened terminals.
  2173. vt.global_cursor_default=
  2174. [VT]
  2175. Format=<-1|0|1>
  2176. Set system-wide default for whether a cursor
  2177. is shown on new VTs. Default is -1,
  2178. i.e. cursors will be created by default unless
  2179. overridden by individual drivers. 0 will hide
  2180. cursors, 1 will display them.
  2181. waveartist= [HW,OSS]
  2182. Format: <io>,<irq>,<dma>,<dma2>
  2183. wd33c93= [HW,SCSI]
  2184. See header of drivers/scsi/wd33c93.c.
  2185. wd7000= [HW,SCSI]
  2186. See header of drivers/scsi/wd7000.c.
  2187. wdt= [WDT] Watchdog
  2188. See Documentation/watchdog/wdt.txt.
  2189. x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
  2190. default x2apic cluster mode on platforms
  2191. supporting x2apic.
  2192. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  2193. xd_geo= See header of drivers/block/xd.c.
  2194. xirc2ps_cs= [NET,PCMCIA]
  2195. Format:
  2196. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  2197. ______________________________________________________________________
  2198. TODO:
  2199. Add documentation for ALSA options.
  2200. Add more DRM drivers.