kernel-parameters.txt 49 KB

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  1. Kernel Parameters
  2. ~~~~~~~~~~~~~~~~~
  3. The following is a consolidated list of the kernel parameters as implemented
  4. (mostly) by the __setup() macro and sorted into English Dictionary order
  5. (defined as ignoring all punctuation and sorting digits before letters in a
  6. case insensitive manner), and with descriptions where known.
  7. Module parameters for loadable modules are specified only as the
  8. parameter name with optional '=' and value as appropriate, such as:
  9. modprobe usbcore blinkenlights=1
  10. Module parameters for modules that are built into the kernel image
  11. are specified on the kernel command line with the module name plus
  12. '.' plus parameter name, with '=' and value if appropriate, such as:
  13. usbcore.blinkenlights=1
  14. This document may not be entirely up to date and comprehensive. The command
  15. "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
  16. module. Loadable modules, after being loaded into the running kernel, also
  17. reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
  18. parameters may be changed at runtime by the command
  19. "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
  20. The parameters listed below are only valid if certain kernel build options were
  21. enabled and if respective hardware is present. The text in square brackets at
  22. the beginning of each description states the restrictions within which a
  23. parameter is applicable:
  24. ACPI ACPI support is enabled.
  25. ALSA ALSA sound support is enabled.
  26. APIC APIC support is enabled.
  27. APM Advanced Power Management support is enabled.
  28. AX25 Appropriate AX.25 support is enabled.
  29. CD Appropriate CD support is enabled.
  30. DEVFS devfs support is enabled.
  31. DRM Direct Rendering Management support is enabled.
  32. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
  33. EFI EFI Partitioning (GPT) is enabled
  34. EIDE EIDE/ATAPI support is enabled.
  35. FB The frame buffer device is enabled.
  36. HW Appropriate hardware is enabled.
  37. IA-32 IA-32 aka i386 architecture is enabled.
  38. IA-64 IA-64 architecture is enabled.
  39. IOSCHED More than one I/O scheduler is enabled.
  40. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  41. ISAPNP ISA PnP code is enabled.
  42. ISDN Appropriate ISDN support is enabled.
  43. JOY Appropriate joystick support is enabled.
  44. LP Printer support is enabled.
  45. LOOP Loopback device support is enabled.
  46. M68k M68k architecture is enabled.
  47. These options have more detailed description inside of
  48. Documentation/m68k/kernel-options.txt.
  49. MCA MCA bus support is enabled.
  50. MDA MDA console support is enabled.
  51. MOUSE Appropriate mouse support is enabled.
  52. MSI Message Signaled Interrupts (PCI).
  53. MTD MTD support is enabled.
  54. NET Appropriate network support is enabled.
  55. NUMA NUMA support is enabled.
  56. NFS Appropriate NFS support is enabled.
  57. OSS OSS sound support is enabled.
  58. PARIDE The ParIDE subsystem is enabled.
  59. PARISC The PA-RISC architecture is enabled.
  60. PCI PCI bus support is enabled.
  61. PCMCIA The PCMCIA subsystem is enabled.
  62. PNP Plug & Play support is enabled.
  63. PPC PowerPC architecture is enabled.
  64. PPT Parallel port support is enabled.
  65. PS2 Appropriate PS/2 support is enabled.
  66. RAM RAM disk support is enabled.
  67. S390 S390 architecture is enabled.
  68. SCSI Appropriate SCSI support is enabled.
  69. A lot of drivers has their options described inside of
  70. Documentation/scsi/.
  71. SELINUX SELinux support is enabled.
  72. SERIAL Serial support is enabled.
  73. SMP The kernel is an SMP kernel.
  74. SPARC Sparc architecture is enabled.
  75. SWSUSP Software suspend is enabled.
  76. TS Appropriate touchscreen support is enabled.
  77. USB USB support is enabled.
  78. USBHID USB Human Interface Device support is enabled.
  79. V4L Video For Linux support is enabled.
  80. VGA The VGA console has been enabled.
  81. VT Virtual terminal support is enabled.
  82. WDT Watchdog support is enabled.
  83. XT IBM PC/XT MFM hard disk support is enabled.
  84. X86-64 X86-64 architecture is enabled.
  85. More X86-64 boot options can be found in
  86. Documentation/x86_64/boot-options.txt .
  87. In addition, the following text indicates that the option:
  88. BUGS= Relates to possible processor bugs on the said processor.
  89. KNL Is a kernel start-up parameter.
  90. BOOT Is a boot loader parameter.
  91. Parameters denoted with BOOT are actually interpreted by the boot
  92. loader, and have no meaning to the kernel directly.
  93. Do not modify the syntax of boot loader parameters without extreme
  94. need or coordination with <Documentation/i386/boot.txt>.
  95. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  96. a trailing = on the name of any parameter states that that parameter will
  97. be entered as an environment variable, whereas its absence indicates that
  98. it will appear as a kernel argument readable via /proc/cmdline by programs
  99. running once the system is up.
  100. 53c7xx= [HW,SCSI] Amiga SCSI controllers
  101. See header of drivers/scsi/53c7xx.c.
  102. See also Documentation/scsi/ncr53c7xx.txt.
  103. acpi= [HW,ACPI] Advanced Configuration and Power Interface
  104. Format: { force | off | ht | strict | noirq }
  105. force -- enable ACPI if default was off
  106. off -- disable ACPI if default was on
  107. noirq -- do not use ACPI for IRQ routing
  108. ht -- run only enough ACPI to enable Hyper Threading
  109. strict -- Be less tolerant of platforms that are not
  110. strictly ACPI specification compliant.
  111. See also Documentation/pm.txt, pci=noacpi
  112. acpi_sleep= [HW,ACPI] Sleep options
  113. Format: { s3_bios, s3_mode }
  114. See Documentation/power/video.txt
  115. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  116. Format: { level | edge | high | low }
  117. acpi_irq_balance [HW,ACPI]
  118. ACPI will balance active IRQs
  119. default in APIC mode
  120. acpi_irq_nobalance [HW,ACPI]
  121. ACPI will not move active IRQs (default)
  122. default in PIC mode
  123. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  124. use by PCI
  125. Format: <irq>,<irq>...
  126. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  127. Format: <irq>,<irq>...
  128. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  129. Format: To spoof as Windows 98: ="Microsoft Windows"
  130. acpi_osi= [HW,ACPI] empty param disables _OSI
  131. acpi_serialize [HW,ACPI] force serialization of AML methods
  132. acpi_skip_timer_override [HW,ACPI]
  133. Recognize and ignore IRQ0/pin2 Interrupt Override.
  134. For broken nForce2 BIOS resulting in XT-PIC timer.
  135. acpi_dbg_layer= [HW,ACPI]
  136. Format: <int>
  137. Each bit of the <int> indicates an ACPI debug layer,
  138. 1: enable, 0: disable. It is useful for boot time
  139. debugging. After system has booted up, it can be set
  140. via /proc/acpi/debug_layer.
  141. acpi_dbg_level= [HW,ACPI]
  142. Format: <int>
  143. Each bit of the <int> indicates an ACPI debug level,
  144. 1: enable, 0: disable. It is useful for boot time
  145. debugging. After system has booted up, it can be set
  146. via /proc/acpi/debug_level.
  147. acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
  148. acpi_generic_hotkey [HW,ACPI]
  149. Allow consolidated generic hotkey driver to
  150. override platform specific driver.
  151. See also Documentation/acpi-hotkey.txt.
  152. enable_timer_pin_1 [i386,x86-64]
  153. Enable PIN 1 of APIC timer
  154. Can be useful to work around chipset bugs
  155. (in particular on some ATI chipsets).
  156. The kernel tries to set a reasonable default.
  157. disable_timer_pin_1 [i386,x86-64]
  158. Disable PIN 1 of APIC timer
  159. Can be useful to work around chipset bugs.
  160. ad1816= [HW,OSS]
  161. Format: <io>,<irq>,<dma>,<dma2>
  162. See also Documentation/sound/oss/AD1816.
  163. ad1848= [HW,OSS]
  164. Format: <io>,<irq>,<dma>,<dma2>,<type>
  165. adlib= [HW,OSS]
  166. Format: <io>
  167. advansys= [HW,SCSI]
  168. See header of drivers/scsi/advansys.c.
  169. advwdt= [HW,WDT] Advantech WDT
  170. Format: <iostart>,<iostop>
  171. aedsp16= [HW,OSS] Audio Excel DSP 16
  172. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  173. See also header of sound/oss/aedsp16.c.
  174. aha152x= [HW,SCSI]
  175. See Documentation/scsi/aha152x.txt.
  176. aha1542= [HW,SCSI]
  177. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  178. aic7xxx= [HW,SCSI]
  179. See Documentation/scsi/aic7xxx.txt.
  180. aic79xx= [HW,SCSI]
  181. See Documentation/scsi/aic79xx.txt.
  182. amijoy.map= [HW,JOY] Amiga joystick support
  183. Map of devices attached to JOY0DAT and JOY1DAT
  184. Format: <a>,<b>
  185. See also Documentation/kernel/input/joystick.txt
  186. analog.map= [HW,JOY] Analog joystick and gamepad support
  187. Specifies type or capabilities of an analog joystick
  188. connected to one of 16 gameports
  189. Format: <type1>,<type2>,..<type16>
  190. apc= [HW,SPARC]
  191. Power management functions (SPARCstation-4/5 + deriv.)
  192. Format: noidle
  193. Disable APC CPU standby support. SPARCstation-Fox does
  194. not play well with APC CPU idle - disable it if you have
  195. APC and your system crashes randomly.
  196. apic= [APIC,i386] Change the output verbosity whilst booting
  197. Format: { quiet (default) | verbose | debug }
  198. Change the amount of debugging information output
  199. when initialising the APIC and IO-APIC components.
  200. apm= [APM] Advanced Power Management
  201. See header of arch/i386/kernel/apm.c.
  202. applicom= [HW]
  203. Format: <mem>,<irq>
  204. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  205. Format: <io>,<irq>,<nodeID>
  206. ataflop= [HW,M68k]
  207. atarimouse= [HW,MOUSE] Atari Mouse
  208. atascsi= [HW,SCSI] Atari SCSI
  209. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  210. EzKey and similar keyboards
  211. atkbd.reset= [HW] Reset keyboard during initialization
  212. atkbd.set= [HW] Select keyboard code set
  213. Format: <int> (2 = AT (default), 3 = PS/2)
  214. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  215. keyboards
  216. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  217. Format: <bool> (0 = real, 1 = synthetic (default))
  218. atkbd.softrepeat= [HW]
  219. Use software keyboard repeat
  220. autotest [IA64]
  221. awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
  222. Format: <io>,<memsize>,<isapnp>
  223. aztcd= [HW,CD] Aztech CD268 CDROM driver
  224. Format: <io>,0x79 (?)
  225. baycom_epp= [HW,AX25]
  226. Format: <io>,<mode>
  227. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  228. Format: <io>,<mode>
  229. See header of drivers/net/hamradio/baycom_par.c.
  230. baycom_ser_fdx= [HW,AX25]
  231. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  232. Format: <io>,<irq>,<mode>[,<baud>]
  233. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  234. baycom_ser_hdx= [HW,AX25]
  235. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  236. Format: <io>,<irq>,<mode>
  237. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  238. blkmtd_device= [HW,MTD]
  239. blkmtd_erasesz=
  240. blkmtd_ro=
  241. blkmtd_bs=
  242. blkmtd_count=
  243. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  244. bttv.radio= Most important insmod options are available as
  245. kernel args too.
  246. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  247. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  248. BusLogic= [HW,SCSI]
  249. See drivers/scsi/BusLogic.c, comment before function
  250. BusLogic_ParseDriverOptions().
  251. c101= [NET] Moxa C101 synchronous serial card
  252. cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
  253. Sometimes CPU hardware bugs make them report the cache
  254. size incorrectly. The kernel will attempt work arounds
  255. to fix known problems, but for some CPUs it is not
  256. possible to determine what the correct size should be.
  257. This option provides an override for these situations.
  258. cdu31a= [HW,CD]
  259. Format: <io>,<irq>[,PAS]
  260. See header of drivers/cdrom/cdu31a.c.
  261. chandev= [HW,NET] Generic channel device initialisation
  262. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  263. Format: { "0" | "1" }
  264. See security/selinux/Kconfig help text.
  265. 0 -- check protection applied by kernel (includes
  266. any implied execute protection).
  267. 1 -- check protection requested by application.
  268. Default value is set via a kernel config option.
  269. Value can be changed at runtime via
  270. /selinux/checkreqprot.
  271. clock= [BUGS=IA-32,HW] gettimeofday timesource override.
  272. Forces specified timesource (if avaliable) to be used
  273. when calculating gettimeofday(). If specicified
  274. timesource is not avalible, it defaults to PIT.
  275. Format: { pit | tsc | cyclone | pmtmr }
  276. disable_8254_timer
  277. enable_8254_timer
  278. [IA32/X86_64] Disable/Enable interrupt 0 timer routing
  279. over the 8254 in addition to over the IO-APIC. The
  280. kernel tries to set a sensible default.
  281. hpet= [IA-32,HPET] option to disable HPET and use PIT.
  282. Format: disable
  283. cm206= [HW,CD]
  284. Format: { auto | [<io>,][<irq>] }
  285. com20020= [HW,NET] ARCnet - COM20020 chipset
  286. Format:
  287. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  288. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  289. Format: <io>[,<irq>]
  290. com90xx= [HW,NET]
  291. ARCnet - COM90xx chipset (memory-mapped buffers)
  292. Format: <io>[,<irq>[,<memstart>]]
  293. condev= [HW,S390] console device
  294. conmode=
  295. console= [KNL] Output console device and options.
  296. tty<n> Use the virtual console device <n>.
  297. ttyS<n>[,options]
  298. ttyUSB0[,options]
  299. Use the specified serial port. The options are of
  300. the form "bbbbpnf", where "bbbb" is the baud rate,
  301. "p" is parity ("n", "o", or "e"), "n" is number of
  302. bits, and "f" is flow control ("r" for RTS or
  303. omit it). Default is "9600n8".
  304. See Documentation/serial-console.txt for more
  305. information. See
  306. Documentation/networking/netconsole.txt for an
  307. alternative.
  308. uart,io,<addr>[,options]
  309. uart,mmio,<addr>[,options]
  310. Start an early, polled-mode console on the 8250/16550
  311. UART at the specified I/O port or MMIO address,
  312. switching to the matching ttyS device later. The
  313. options are the same as for ttyS, above.
  314. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  315. Format:
  316. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  317. cpia_pp= [HW,PPT]
  318. Format: { parport<nr> | auto | none }
  319. crashkernel=nn[KMG]@ss[KMG]
  320. [KNL] Reserve a chunk of physical memory to
  321. hold a kernel to switch to with kexec on panic.
  322. cs4232= [HW,OSS]
  323. Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
  324. cs89x0_dma= [HW,NET]
  325. Format: <dma>
  326. cs89x0_media= [HW,NET]
  327. Format: { rj45 | aui | bnc }
  328. cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
  329. dasd= [HW,NET]
  330. See header of drivers/s390/block/dasd_devmap.c.
  331. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  332. (one device per port)
  333. Format: <port#>,<type>
  334. See also Documentation/input/joystick-parport.txt
  335. debug [KNL] Enable kernel debugging (events log level).
  336. decnet= [HW,NET]
  337. Format: <area>[,<node>]
  338. See also Documentation/networking/decnet.txt.
  339. devfs= [DEVFS]
  340. See Documentation/filesystems/devfs/boot-options.
  341. dhash_entries= [KNL]
  342. Set number of hash buckets for dentry cache.
  343. digi= [HW,SERIAL]
  344. IO parameters + enable/disable command.
  345. digiepca= [HW,SERIAL]
  346. See drivers/char/README.epca and
  347. Documentation/digiepca.txt.
  348. dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
  349. support available.
  350. Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
  351. dmasound= [HW,OSS] Sound subsystem buffers
  352. dscc4.setup= [NET]
  353. dtc3181e= [HW,SCSI]
  354. earlyprintk= [IA-32,X86-64]
  355. earlyprintk=vga
  356. earlyprintk=serial[,ttySn[,baudrate]]
  357. Append ",keep" to not disable it when the real console
  358. takes over.
  359. Only vga or serial at a time, not both.
  360. Currently only ttyS0 and ttyS1 are supported.
  361. Interaction with the standard serial driver is not
  362. very good.
  363. The VGA output is eventually overwritten by the real
  364. console.
  365. eata= [HW,SCSI]
  366. ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
  367. Format: <int>
  368. 0: polling mode
  369. non-0: interrupt mode (default)
  370. eda= [HW,PS2]
  371. edb= [HW,PS2]
  372. edd= [EDD]
  373. Format: {"of[f]" | "sk[ipmbr]"}
  374. See comment in arch/i386/boot/edd.S
  375. eicon= [HW,ISDN]
  376. Format: <id>,<membase>,<irq>
  377. eisa_irq_edge= [PARISC,HW]
  378. See header of drivers/parisc/eisa.c.
  379. elanfreq= [IA-32]
  380. See comment before function elanfreq_setup() in
  381. arch/i386/kernel/cpu/cpufreq/elanfreq.c.
  382. elevator= [IOSCHED]
  383. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  384. See Documentation/block/as-iosched.txt and
  385. Documentation/block/deadline-iosched.txt for details.
  386. elfcorehdr= [IA-32, X86_64]
  387. Specifies physical address of start of kernel core
  388. image elf header. Generally kexec loader will
  389. pass this option to capture kernel.
  390. See Documentation/kdump/kdump.txt for details.
  391. enforcing [SELINUX] Set initial enforcing status.
  392. Format: {"0" | "1"}
  393. See security/selinux/Kconfig help text.
  394. 0 -- permissive (log only, no denials).
  395. 1 -- enforcing (deny and log).
  396. Default value is 0.
  397. Value can be changed at runtime via /selinux/enforce.
  398. es1370= [HW,OSS]
  399. Format: <lineout>[,<micbias>]
  400. See also header of sound/oss/es1370.c.
  401. es1371= [HW,OSS]
  402. Format: <spdif>,[<nomix>,[<amplifier>]]
  403. See also header of sound/oss/es1371.c.
  404. ether= [HW,NET] Ethernet cards parameters
  405. This option is obsoleted by the "netdev=" option, which
  406. has equivalent usage. See its documentation for details.
  407. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  408. Format: <io>[,<irq>]
  409. fd_mcs= [HW,SCSI]
  410. See header of drivers/scsi/fd_mcs.c.
  411. fdomain= [HW,SCSI]
  412. See header of drivers/scsi/fdomain.c.
  413. floppy= [HW]
  414. See Documentation/floppy.txt.
  415. ftape= [HW] Floppy Tape subsystem debugging options.
  416. See Documentation/ftape.txt.
  417. gamecon.map[2|3]=
  418. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  419. support via parallel port (up to 5 devices per port)
  420. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  421. See also Documentation/input/joystick-parport.txt
  422. gamma= [HW,DRM]
  423. gdth= [HW,SCSI]
  424. See header of drivers/scsi/gdth.c.
  425. gpt [EFI] Forces disk with valid GPT signature but
  426. invalid Protective MBR to be treated as GPT.
  427. gscd= [HW,CD]
  428. Format: <io>
  429. gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
  430. gus= [HW,OSS]
  431. Format: <io>,<irq>,<dma>,<dma16>
  432. gvp11= [HW,SCSI]
  433. hashdist= [KNL,NUMA] Large hashes allocated during boot
  434. are distributed across NUMA nodes. Defaults on
  435. for IA-64, off otherwise.
  436. Format: 0 | 1 (for off | on)
  437. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  438. hd= [EIDE] (E)IDE hard drive subsystem geometry
  439. Format: <cyl>,<head>,<sect>
  440. hd?= [HW] (E)IDE subsystem
  441. hd?lun= See Documentation/ide.txt.
  442. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  443. size of <nn>. This works even on boxes that have no
  444. highmem otherwise. This also works to reduce highmem
  445. size on bigger boxes.
  446. hisax= [HW,ISDN]
  447. See Documentation/isdn/README.HiSax.
  448. hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
  449. noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
  450. i8042.direct [HW] Put keyboard port into non-translated mode
  451. i8042.dumbkbd [HW] Pretend that controlled can only read data from
  452. keyboard and can not control its state
  453. (Don't attempt to blink the leds)
  454. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  455. i8042.nokbd [HW] Don't check/create keyboard port
  456. i8042.nomux [HW] Don't check presence of an active multiplexing
  457. controller
  458. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  459. controllers
  460. i8042.panicblink=
  461. [HW] Frequency with which keyboard LEDs should blink
  462. when kernel panics (default is 0.5 sec)
  463. i8042.reset [HW] Reset the controller during init and cleanup
  464. i8042.unlock [HW] Unlock (ignore) the keylock
  465. i810= [HW,DRM]
  466. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  467. indicates that the driver is running on unsupported
  468. hardware.
  469. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  470. does not match list of supported models.
  471. i8k.power_status
  472. [HW] Report power status in /proc/i8k
  473. (disabled by default)
  474. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  475. capability is set.
  476. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  477. See Documentation/mca.txt.
  478. icn= [HW,ISDN]
  479. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  480. ide= [HW] (E)IDE subsystem
  481. Format: ide=nodma or ide=doubler or ide=reverse
  482. See Documentation/ide.txt.
  483. ide?= [HW] (E)IDE subsystem
  484. Format: ide?=noprobe or chipset specific parameters.
  485. See Documentation/ide.txt.
  486. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  487. See Documentation/ide.txt.
  488. idle= [HW]
  489. Format: idle=poll or idle=halt
  490. ihash_entries= [KNL]
  491. Set number of hash buckets for inode cache.
  492. in2000= [HW,SCSI]
  493. See header of drivers/scsi/in2000.c.
  494. init= [KNL]
  495. Format: <full_path>
  496. Run specified binary instead of /sbin/init as init
  497. process.
  498. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  499. for working out where the kernel is dying during
  500. startup.
  501. initrd= [BOOT] Specify the location of the initial ramdisk
  502. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  503. Format: <irq>
  504. combined_mode= [HW] control which driver uses IDE ports in combined
  505. mode: legacy IDE driver, libata, or both
  506. (in the libata case, libata.atapi_enabled=1 may be
  507. useful as well). Note that using the ide or libata
  508. options may affect your device naming (e.g. by
  509. changing hdc to sdb).
  510. Format: combined (default), ide, or libata
  511. inttest= [IA64]
  512. io7= [HW] IO7 for Marvel based alpha systems
  513. See comment before marvel_specify_io7 in
  514. arch/alpha/kernel/core_marvel.c.
  515. ip= [IP_PNP]
  516. See Documentation/nfsroot.txt.
  517. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  518. See comment before ip2_setup() in drivers/char/ip2.c.
  519. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  520. See header of drivers/scsi/ips.c.
  521. irqfixup [HW]
  522. When an interrupt is not handled search all handlers
  523. for it. Intended to get systems with badly broken
  524. firmware running.
  525. irqpoll [HW]
  526. When an interrupt is not handled search all handlers
  527. for it. Also check all handlers each timer
  528. interrupt. Intended to get systems with badly broken
  529. firmware running.
  530. isapnp= [ISAPNP]
  531. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  532. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  533. Format: <cpu number>,...,<cpu number>
  534. This option can be used to specify one or more CPUs
  535. to isolate from the general SMP balancing and scheduling
  536. algorithms. The only way to move a process onto or off
  537. an "isolated" CPU is via the CPU affinity syscalls.
  538. <cpu number> begins at 0 and the maximum value is
  539. "number of CPUs in system - 1".
  540. This option is the preferred way to isolate CPUs. The
  541. alternative -- manually setting the CPU mask of all
  542. tasks in the system -- can cause problems and
  543. suboptimal load balancer performance.
  544. isp16= [HW,CD]
  545. Format: <io>,<irq>,<dma>,<setup>
  546. iucv= [HW,NET]
  547. js= [HW,JOY] Analog joystick
  548. See Documentation/input/joystick.txt.
  549. keepinitrd [HW,ARM]
  550. kstack=N [IA-32,X86-64] Print N words from the kernel stack
  551. in oops dumps.
  552. l2cr= [PPC]
  553. lapic [IA-32,APIC] Enable the local APIC even if BIOS
  554. disabled it.
  555. lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
  556. Format: addr:<io>,irq:<irq>
  557. llsc*= [IA64] See function print_params() in
  558. arch/ia64/sn/kernel/llsc4.c.
  559. load_ramdisk= [RAM] List of ramdisks to load from floppy
  560. See Documentation/ramdisk.txt.
  561. lockd.nlm_grace_period=P [NFS] Assign grace period.
  562. Format: <integer>
  563. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  564. Format: <integer>
  565. lockd.nlm_timeout=T [NFS] Assign timeout value.
  566. Format: <integer>
  567. lockd.nlm_udpport=M [NFS] Assign UDP port.
  568. Format: <integer>
  569. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  570. Format: <irq>
  571. loglevel= All Kernel Messages with a loglevel smaller than the
  572. console loglevel will be printed to the console. It can
  573. also be changed with klogd or other programs. The
  574. loglevels are defined as follows:
  575. 0 (KERN_EMERG) system is unusable
  576. 1 (KERN_ALERT) action must be taken immediately
  577. 2 (KERN_CRIT) critical conditions
  578. 3 (KERN_ERR) error conditions
  579. 4 (KERN_WARNING) warning conditions
  580. 5 (KERN_NOTICE) normal but significant condition
  581. 6 (KERN_INFO) informational
  582. 7 (KERN_DEBUG) debug-level messages
  583. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  584. Format: { n | nk | nM }
  585. n must be a power of two. The default size
  586. is set in the kernel config file.
  587. lp=0 [LP] Specify parallel ports to use, e.g,
  588. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  589. lp=reset first parallel port). 'lp=0' disables the
  590. lp=auto printer driver. 'lp=reset' (which can be
  591. specified in addition to the ports) causes
  592. attached printers to be reset. Using
  593. lp=port1,port2,... specifies the parallel ports
  594. to associate lp devices with, starting with
  595. lp0. A port specification may be 'none' to skip
  596. that lp device, or a parport name such as
  597. 'parport0'. Specifying 'lp=auto' instead of a
  598. port specification list means that device IDs
  599. from each port should be examined, to see if
  600. an IEEE 1284-compliant printer is attached; if
  601. so, the driver will manage that printer.
  602. See also header of drivers/char/lp.c.
  603. lpj=n [KNL]
  604. Sets loops_per_jiffy to given constant, thus avoiding
  605. time-consuming boot-time autodetection (up to 250 ms per
  606. CPU). 0 enables autodetection (default). To determine
  607. the correct value for your kernel, boot with normal
  608. autodetection and see what value is printed. Note that
  609. on SMP systems the preset will be applied to all CPUs,
  610. which is likely to cause problems if your CPUs need
  611. significantly divergent settings. An incorrect value
  612. will cause delays in the kernel to be wrong, leading to
  613. unpredictable I/O errors and other breakage. Although
  614. unlikely, in the extreme case this might damage your
  615. hardware.
  616. ltpc= [NET]
  617. Format: <io>,<irq>,<dma>
  618. mac5380= [HW,SCSI] Format:
  619. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  620. mac53c9x= [HW,SCSI] Format:
  621. <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  622. machvec= [IA64] Force the use of a particular machine-vector
  623. (machvec) in a generic kernel.
  624. Example: machvec=hpzx1_swiotlb
  625. mad16= [HW,OSS] Format:
  626. <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
  627. maui= [HW,OSS]
  628. Format: <io>,<irq>
  629. max_loop= [LOOP] Maximum number of loopback devices that can
  630. be mounted
  631. Format: <1-256>
  632. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  633. should make use of
  634. max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
  635. equal to this physical address is ignored.
  636. max_luns= [SCSI] Maximum number of LUNs to probe.
  637. Should be between 1 and 2^32-1.
  638. max_report_luns=
  639. [SCSI] Maximum number of LUNs received.
  640. Should be between 1 and 16384.
  641. mca-pentium [BUGS=IA-32]
  642. mcatest= [IA-64]
  643. mcd= [HW,CD]
  644. Format: <port>,<irq>,<mitsumi_bug_93_wait>
  645. mcdx= [HW,CD]
  646. mce [IA-32] Machine Check Exception
  647. md= [HW] RAID subsystems devices and level
  648. See Documentation/md.txt.
  649. mdacon= [MDA]
  650. Format: <first>,<last>
  651. Specifies range of consoles to be captured by the MDA.
  652. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  653. Amount of memory to be used when the kernel is not able
  654. to see the whole system memory or for test.
  655. [IA-32] Use together with memmap= to avoid physical
  656. address space collisions. Without memmap= PCI devices
  657. could be placed at addresses belonging to unused RAM.
  658. mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
  659. memory.
  660. memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
  661. E820 memory map, as specified by the user.
  662. Such memmap=exactmap lines can be constructed based on
  663. BIOS output or other requirements. See the memmap=nn@ss
  664. option description.
  665. memmap=nn[KMG]@ss[KMG]
  666. [KNL] Force usage of a specific region of memory
  667. Region of memory to be used, from ss to ss+nn.
  668. memmap=nn[KMG]#ss[KMG]
  669. [KNL,ACPI] Mark specific memory as ACPI data.
  670. Region of memory to be used, from ss to ss+nn.
  671. memmap=nn[KMG]$ss[KMG]
  672. [KNL,ACPI] Mark specific memory as reserved.
  673. Region of memory to be used, from ss to ss+nn.
  674. meye.*= [HW] Set MotionEye Camera parameters
  675. See Documentation/video4linux/meye.txt.
  676. mga= [HW,DRM]
  677. migration_cost=
  678. [KNL,SMP] debug: override scheduler migration costs
  679. Format: <level-1-usecs>,<level-2-usecs>,...
  680. This debugging option can be used to override the
  681. default scheduler migration cost matrix. The numbers
  682. are indexed by 'CPU domain distance'.
  683. E.g. migration_cost=1000,2000,3000 on an SMT NUMA
  684. box will set up an intra-core migration cost of
  685. 1 msec, an inter-core migration cost of 2 msecs,
  686. and an inter-node migration cost of 3 msecs.
  687. WARNING: using the wrong values here can break
  688. scheduler performance, so it's only for scheduler
  689. development purposes, not production environments.
  690. migration_debug=
  691. [KNL,SMP] migration cost auto-detect verbosity
  692. Format=<0|1|2>
  693. If a system's migration matrix reported at bootup
  694. seems erroneous then this option can be used to
  695. increase verbosity of the detection process.
  696. We default to 0 (no extra messages), 1 will print
  697. some more information, and 2 will be really
  698. verbose (probably only useful if you also have a
  699. serial console attached to the system).
  700. migration_factor=
  701. [KNL,SMP] multiply/divide migration costs by a factor
  702. Format=<percent>
  703. This debug option can be used to proportionally
  704. increase or decrease the auto-detected migration
  705. costs for all entries of the migration matrix.
  706. E.g. migration_factor=150 will increase migration
  707. costs by 50%. (and thus the scheduler will be less
  708. eager migrating cache-hot tasks)
  709. migration_factor=80 will decrease migration costs
  710. by 20%. (thus the scheduler will be more eager to
  711. migrate tasks)
  712. WARNING: using the wrong values here can break
  713. scheduler performance, so it's only for scheduler
  714. development purposes, not production environments.
  715. mousedev.tap_time=
  716. [MOUSE] Maximum time between finger touching and
  717. leaving touchpad surface for touch to be considered
  718. a tap and be reported as a left button click (for
  719. touchpads working in absolute mode only).
  720. Format: <msecs>
  721. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  722. reporting absolute coordinates, such as tablets
  723. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  724. reporting absolute coordinates, such as tablets
  725. mpu401= [HW,OSS]
  726. Format: <io>,<irq>
  727. MTD_Partition= [MTD]
  728. Format: <name>,<region-number>,<size>,<offset>
  729. MTD_Region= [MTD] Format:
  730. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  731. mtdparts= [MTD]
  732. See drivers/mtd/cmdline.c.
  733. mtouchusb.raw_coordinates=
  734. [HW] Make the MicroTouch USB driver use raw coordinates
  735. ('y', default) or cooked coordinates ('n')
  736. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  737. NCR_D700= [HW,SCSI]
  738. See header of drivers/scsi/NCR_D700.c.
  739. ncr5380= [HW,SCSI]
  740. ncr53c400= [HW,SCSI]
  741. ncr53c400a= [HW,SCSI]
  742. ncr53c406a= [HW,SCSI]
  743. ncr53c8xx= [HW,SCSI]
  744. netdev= [NET] Network devices parameters
  745. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  746. Note that mem_start is often overloaded to mean
  747. something different and driver-specific.
  748. This usage is only documented in each driver source
  749. file if at all.
  750. nfsaddrs= [NFS]
  751. See Documentation/nfsroot.txt.
  752. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  753. See Documentation/nfsroot.txt.
  754. nfs.callback_tcpport=
  755. [NFS] set the TCP port on which the NFSv4 callback
  756. channel should listen.
  757. nfs.idmap_cache_timeout=
  758. [NFS] set the maximum lifetime for idmapper cache
  759. entries.
  760. nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
  761. no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
  762. emulation library even if a 387 maths coprocessor
  763. is present.
  764. noalign [KNL,ARM]
  765. noapic [SMP,APIC] Tells the kernel to not make use of any
  766. IOAPICs that may be present in the system.
  767. noasync [HW,M68K] Disables async and sync negotiation for
  768. all devices.
  769. nobats [PPC] Do not use BATs for mapping kernel lowmem
  770. on "Classic" PPC cores.
  771. nocache [ARM]
  772. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  773. noexec [IA-64]
  774. noexec [IA-32,X86-64]
  775. noexec=on: enable non-executable mappings (default)
  776. noexec=off: disable nn-executable mappings
  777. nofxsr [BUGS=IA-32] Disables x86 floating point extended
  778. register save and restore. The kernel will only save
  779. legacy floating-point registers on task switch.
  780. nohlt [BUGS=ARM]
  781. no-hlt [BUGS=IA-32] Tells the kernel that the hlt
  782. instruction doesn't work correctly and not to
  783. use it.
  784. nohalt [IA-64] Tells the kernel not to use the power saving
  785. function PAL_HALT_LIGHT when idle. This increases
  786. power-consumption. On the positive side, it reduces
  787. interrupt wake-up latency, which may improve performance
  788. in certain environments such as networked servers or
  789. real-time systems.
  790. noirqdebug [IA-32] Disables the code which attempts to detect and
  791. disable unhandled interrupt sources.
  792. noisapnp [ISAPNP] Disables ISA PnP code.
  793. noinitrd [RAM] Tells the kernel not to load any configured
  794. initial RAM disk.
  795. nointroute [IA-64]
  796. nolapic [IA-32,APIC] Do not enable or use the local APIC.
  797. noltlbs [PPC] Do not use large page/tlb entries for kernel
  798. lowmem mapping on PPC40x.
  799. nomca [IA-64] Disable machine check abort handling
  800. nomce [IA-32] Machine Check Exception
  801. noresidual [PPC] Don't use residual data on PReP machines.
  802. noresume [SWSUSP] Disables resume and restores original swap
  803. space.
  804. no-scroll [VGA] Disables scrollback.
  805. This is required for the Braillex ib80-piezo Braille
  806. reader made by F.H. Papenmeier (Germany).
  807. nosbagart [IA-64]
  808. nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
  809. nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
  810. nosync [HW,M68K] Disables sync negotiation for all devices.
  811. notsc [BUGS=IA-32] Disable Time Stamp Counter
  812. nousb [USB] Disable the USB subsystem
  813. nowb [ARM]
  814. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  815. opl3= [HW,OSS]
  816. Format: <io>
  817. opl3sa= [HW,OSS]
  818. Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
  819. opl3sa2= [HW,OSS] Format:
  820. <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
  821. oprofile.timer= [HW]
  822. Use timer interrupt instead of performance counters
  823. optcd= [HW,CD]
  824. Format: <io>
  825. osst= [HW,SCSI] SCSI Tape Driver
  826. Format: <buffer_size>,<write_threshold>
  827. See also Documentation/scsi/st.txt.
  828. panic= [KNL] Kernel behaviour on panic
  829. Format: <timeout>
  830. parkbd.port= [HW] Parallel port number the keyboard adapter is
  831. connected to, default is 0.
  832. Format: <parport#>
  833. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  834. 0 for XT, 1 for AT (default is AT).
  835. Format: <mode>
  836. parport= [HW,PPT] Specify parallel ports. 0 disables.
  837. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  838. Use 'auto' to force the driver to use any
  839. IRQ/DMA settings detected (the default is to
  840. ignore detected IRQ/DMA settings because of
  841. possible conflicts). You can specify the base
  842. address, IRQ, and DMA settings; IRQ and DMA
  843. should be numbers, or 'auto' (for using detected
  844. settings on that particular port), or 'nofifo'
  845. (to avoid using a FIFO even if it is detected).
  846. Parallel ports are assigned in the order they
  847. are specified on the command line, starting
  848. with parport0.
  849. parport_init_mode= [HW,PPT]
  850. Configure VIA parallel port to operate in
  851. a specific mode. This is necessary on Pegasos
  852. computer where firmware has no options for setting
  853. up parallel port mode and sets it to spp.
  854. Currently this function knows 686a and 8231 chips.
  855. Format: [spp|ps2|epp|ecp|ecpepp]
  856. pas2= [HW,OSS] Format:
  857. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  858. pas16= [HW,SCSI]
  859. See header of drivers/scsi/pas16.c.
  860. pause_on_oops=
  861. Halt all CPUs after the first oops has been printed for
  862. the specified number of seconds. This is to be used if
  863. your oopses keep scrolling off the screen.
  864. pcbit= [HW,ISDN]
  865. pcd. [PARIDE]
  866. See header of drivers/block/paride/pcd.c.
  867. See also Documentation/paride.txt.
  868. pci=option[,option...] [PCI] various PCI subsystem options:
  869. off [IA-32] don't probe for the PCI bus
  870. bios [IA-32] force use of PCI BIOS, don't access
  871. the hardware directly. Use this if your machine
  872. has a non-standard PCI host bridge.
  873. nobios [IA-32] disallow use of PCI BIOS, only direct
  874. hardware access methods are allowed. Use this
  875. if you experience crashes upon bootup and you
  876. suspect they are caused by the BIOS.
  877. conf1 [IA-32] Force use of PCI Configuration
  878. Mechanism 1.
  879. conf2 [IA-32] Force use of PCI Configuration
  880. Mechanism 2.
  881. nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
  882. Configuration
  883. nomsi [MSI] If the PCI_MSI kernel config parameter is
  884. enabled, this kernel boot option can be used to
  885. disable the use of MSI interrupts system-wide.
  886. nosort [IA-32] Don't sort PCI devices according to
  887. order given by the PCI BIOS. This sorting is
  888. done to get a device order compatible with
  889. older kernels.
  890. biosirq [IA-32] Use PCI BIOS calls to get the interrupt
  891. routing table. These calls are known to be buggy
  892. on several machines and they hang the machine
  893. when used, but on other computers it's the only
  894. way to get the interrupt routing table. Try
  895. this option if the kernel is unable to allocate
  896. IRQs or discover secondary PCI buses on your
  897. motherboard.
  898. rom [IA-32] Assign address space to expansion ROMs.
  899. Use with caution as certain devices share
  900. address decoders between ROMs and other
  901. resources.
  902. irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
  903. assigned automatically to PCI devices. You can
  904. make the kernel exclude IRQs of your ISA cards
  905. this way.
  906. pirqaddr=0xAAAAA [IA-32] Specify the physical address
  907. of the PIRQ table (normally generated
  908. by the BIOS) if it is outside the
  909. F0000h-100000h range.
  910. lastbus=N [IA-32] Scan all buses thru bus #N. Can be
  911. useful if the kernel is unable to find your
  912. secondary buses and you want to tell it
  913. explicitly which ones they are.
  914. assign-busses [IA-32] Always assign all PCI bus
  915. numbers ourselves, overriding
  916. whatever the firmware may have done.
  917. usepirqmask [IA-32] Honor the possible IRQ mask stored
  918. in the BIOS $PIR table. This is needed on
  919. some systems with broken BIOSes, notably
  920. some HP Pavilion N5400 and Omnibook XE3
  921. notebooks. This will have no effect if ACPI
  922. IRQ routing is enabled.
  923. noacpi [IA-32] Do not use ACPI for IRQ routing
  924. or for PCI scanning.
  925. routeirq Do IRQ routing for all PCI devices.
  926. This is normally done in pci_enable_device(),
  927. so this option is a temporary workaround
  928. for broken drivers that don't call it.
  929. firmware [ARM] Do not re-enumerate the bus but instead
  930. just use the configuration from the
  931. bootloader. This is currently used on
  932. IXP2000 systems where the bus has to be
  933. configured a certain way for adjunct CPUs.
  934. pcmv= [HW,PCMCIA] BadgePAD 4
  935. pd. [PARIDE]
  936. See Documentation/paride.txt.
  937. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  938. boot time.
  939. Format: { 0 | 1 }
  940. See arch/parisc/kernel/pdc_chassis.c
  941. pf. [PARIDE]
  942. See Documentation/paride.txt.
  943. pg. [PARIDE]
  944. See Documentation/paride.txt.
  945. pirq= [SMP,APIC] Manual mp-table setup
  946. See Documentation/i386/IO-APIC.txt.
  947. plip= [PPT,NET] Parallel port network link
  948. Format: { parport<nr> | timid | 0 }
  949. See also Documentation/parport.txt.
  950. pnpacpi= [ACPI]
  951. { off }
  952. pnpbios= [ISAPNP]
  953. { on | off | curr | res | no-curr | no-res }
  954. pnp_reserve_irq=
  955. [ISAPNP] Exclude IRQs for the autoconfiguration
  956. pnp_reserve_dma=
  957. [ISAPNP] Exclude DMAs for the autoconfiguration
  958. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  959. Ranges are in pairs (I/O port base and size).
  960. pnp_reserve_mem=
  961. [ISAPNP] Exclude memory regions for the
  962. autoconfiguration.
  963. Ranges are in pairs (memory base and size).
  964. profile= [KNL] Enable kernel profiling via /proc/profile
  965. Format: [schedule,]<number>
  966. Param: "schedule" - profile schedule points.
  967. Param: <number> - step/bucket size as a power of 2 for
  968. statistical time based profiling.
  969. processor.max_cstate= [HW,ACPI]
  970. Limit processor to maximum C-state
  971. max_cstate=9 overrides any DMI blacklist limit.
  972. processor.nocst [HW,ACPI]
  973. Ignore the _CST method to determine C-states,
  974. instead using the legacy FADT method
  975. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  976. before loading.
  977. See Documentation/ramdisk.txt.
  978. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  979. probe for; one of (bare|imps|exps|lifebook|any).
  980. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  981. per second.
  982. psmouse.resetafter= [HW,MOUSE]
  983. Try to reset the device after so many bad packets
  984. (0 = never).
  985. psmouse.resolution=
  986. [HW,MOUSE] Set desired mouse resolution, in dpi.
  987. psmouse.smartscroll=
  988. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  989. 0 = disabled, 1 = enabled (default).
  990. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  991. Format:
  992. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  993. pt. [PARIDE]
  994. See Documentation/paride.txt.
  995. quiet= [KNL] Disable log messages
  996. r128= [HW,DRM]
  997. raid= [HW,RAID]
  998. See Documentation/md.txt.
  999. ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
  1000. See Documentation/ramdisk.txt.
  1001. ramdisk_blocksize= [RAM]
  1002. See Documentation/ramdisk.txt.
  1003. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1004. New name for the ramdisk parameter.
  1005. See Documentation/ramdisk.txt.
  1006. rcu.blimit= [KNL,BOOT] Set maximum number of finished
  1007. RCU callbacks to process in one batch.
  1008. rcu.qhimark= [KNL,BOOT] Set threshold of queued
  1009. RCU callbacks over which batch limiting is disabled.
  1010. rcu.qlowmark= [KNL,BOOT] Set threshold of queued
  1011. RCU callbacks below which batch limiting is re-enabled.
  1012. rcu.rsinterval= [KNL,BOOT,SMP] Set the number of additional
  1013. RCU callbacks to queued before forcing reschedule
  1014. on all cpus.
  1015. rdinit= [KNL]
  1016. Format: <full_path>
  1017. Run specified binary instead of /init from the ramdisk,
  1018. used for early userspace startup. See initrd.
  1019. reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1020. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1021. See arch/*/kernel/reboot.c.
  1022. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1023. resume= [SWSUSP]
  1024. Specify the partition device for software suspend
  1025. rhash_entries= [KNL,NET]
  1026. Set number of hash buckets for route cache
  1027. riscom8= [HW,SERIAL]
  1028. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1029. ro [KNL] Mount root device read-only on boot
  1030. root= [KNL] Root filesystem
  1031. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1032. mount the root filesystem
  1033. rootflags= [KNL] Set root filesystem mount option string
  1034. rootfstype= [KNL] Set root filesystem type
  1035. rw [KNL] Mount root device read-write on boot
  1036. S [KNL] Run init in single mode
  1037. sa1100ir [NET]
  1038. See drivers/net/irda/sa1100_ir.c.
  1039. sb= [HW,OSS]
  1040. Format: <io>,<irq>,<dma>,<dma2>
  1041. sbni= [NET] Granch SBNI12 leased line adapter
  1042. sbpcd= [HW,CD] Soundblaster CD adapter
  1043. Format: <io>,<type>
  1044. See a comment before function sbpcd_setup() in
  1045. drivers/cdrom/sbpcd.c.
  1046. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1047. Format: <io>[,<timeout>[,<isapnp>]]
  1048. scsi_debug_*= [SCSI]
  1049. See drivers/scsi/scsi_debug.c.
  1050. scsi_default_dev_flags=
  1051. [SCSI] SCSI default device flags
  1052. Format: <integer>
  1053. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1054. Format: <vendor>:<model>:<flags>
  1055. (flags are integer value)
  1056. scsi_logging= [SCSI]
  1057. selinux [SELINUX] Disable or enable SELinux at boot time.
  1058. Format: { "0" | "1" }
  1059. See security/selinux/Kconfig help text.
  1060. 0 -- disable.
  1061. 1 -- enable.
  1062. Default value is set via kernel config option.
  1063. If enabled at boot time, /selinux/disable can be used
  1064. later to disable prior to initial policy load.
  1065. selinux_compat_net =
  1066. [SELINUX] Set initial selinux_compat_net flag value.
  1067. Format: { "0" | "1" }
  1068. 0 -- use new secmark-based packet controls
  1069. 1 -- use legacy packet controls
  1070. Default value is 0 (preferred).
  1071. Value can be changed at runtime via
  1072. /selinux/compat_net.
  1073. serialnumber [BUGS=IA-32]
  1074. sg_def_reserved_size= [SCSI]
  1075. sgalaxy= [HW,OSS]
  1076. Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
  1077. shapers= [NET]
  1078. Maximal number of shapers.
  1079. sim710= [SCSI,HW]
  1080. See header of drivers/scsi/sim710.c.
  1081. simeth= [IA-64]
  1082. simscsi=
  1083. sjcd= [HW,CD]
  1084. Format: <io>,<irq>,<dma>
  1085. See header of drivers/cdrom/sjcd.c.
  1086. slram= [HW,MTD]
  1087. smart2= [HW]
  1088. Format: <io1>[,<io2>[,...,<io8>]]
  1089. snd-ad1816a= [HW,ALSA]
  1090. snd-ad1848= [HW,ALSA]
  1091. snd-ali5451= [HW,ALSA]
  1092. snd-als100= [HW,ALSA]
  1093. snd-als4000= [HW,ALSA]
  1094. snd-azt2320= [HW,ALSA]
  1095. snd-cmi8330= [HW,ALSA]
  1096. snd-cmipci= [HW,ALSA]
  1097. snd-cs4231= [HW,ALSA]
  1098. snd-cs4232= [HW,ALSA]
  1099. snd-cs4236= [HW,ALSA]
  1100. snd-cs4281= [HW,ALSA]
  1101. snd-cs46xx= [HW,ALSA]
  1102. snd-dt019x= [HW,ALSA]
  1103. snd-dummy= [HW,ALSA]
  1104. snd-emu10k1= [HW,ALSA]
  1105. snd-ens1370= [HW,ALSA]
  1106. snd-ens1371= [HW,ALSA]
  1107. snd-es968= [HW,ALSA]
  1108. snd-es1688= [HW,ALSA]
  1109. snd-es18xx= [HW,ALSA]
  1110. snd-es1938= [HW,ALSA]
  1111. snd-es1968= [HW,ALSA]
  1112. snd-fm801= [HW,ALSA]
  1113. snd-gusclassic= [HW,ALSA]
  1114. snd-gusextreme= [HW,ALSA]
  1115. snd-gusmax= [HW,ALSA]
  1116. snd-hdsp= [HW,ALSA]
  1117. snd-ice1712= [HW,ALSA]
  1118. snd-intel8x0= [HW,ALSA]
  1119. snd-interwave= [HW,ALSA]
  1120. snd-interwave-stb=
  1121. [HW,ALSA]
  1122. snd-korg1212= [HW,ALSA]
  1123. snd-maestro3= [HW,ALSA]
  1124. snd-mpu401= [HW,ALSA]
  1125. snd-mtpav= [HW,ALSA]
  1126. snd-nm256= [HW,ALSA]
  1127. snd-opl3sa2= [HW,ALSA]
  1128. snd-opti92x-ad1848=
  1129. [HW,ALSA]
  1130. snd-opti92x-cs4231=
  1131. [HW,ALSA]
  1132. snd-opti93x= [HW,ALSA]
  1133. snd-pmac= [HW,ALSA]
  1134. snd-rme32= [HW,ALSA]
  1135. snd-rme96= [HW,ALSA]
  1136. snd-rme9652= [HW,ALSA]
  1137. snd-sb8= [HW,ALSA]
  1138. snd-sb16= [HW,ALSA]
  1139. snd-sbawe= [HW,ALSA]
  1140. snd-serial= [HW,ALSA]
  1141. snd-sgalaxy= [HW,ALSA]
  1142. snd-sonicvibes= [HW,ALSA]
  1143. snd-sun-amd7930=
  1144. [HW,ALSA]
  1145. snd-sun-cs4231= [HW,ALSA]
  1146. snd-trident= [HW,ALSA]
  1147. snd-usb-audio= [HW,ALSA,USB]
  1148. snd-via82xx= [HW,ALSA]
  1149. snd-virmidi= [HW,ALSA]
  1150. snd-wavefront= [HW,ALSA]
  1151. snd-ymfpci= [HW,ALSA]
  1152. sonicvibes= [HW,OSS]
  1153. Format: <reverb>
  1154. sonycd535= [HW,CD]
  1155. Format: <io>[,<irq>]
  1156. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1157. See Documentation/sonypi.txt
  1158. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1159. See Documentation/specialix.txt.
  1160. spia_io_base= [HW,MTD]
  1161. spia_fio_base=
  1162. spia_pedr=
  1163. spia_peddr=
  1164. sscape= [HW,OSS]
  1165. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1166. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1167. See Documentation/scsi/st.txt.
  1168. st0x= [HW,SCSI]
  1169. See header of drivers/scsi/seagate.c.
  1170. sti= [PARISC,HW]
  1171. Format: <num>
  1172. Set the STI (builtin display/keyboard on the HP-PARISC
  1173. machines) console (graphic card) which should be used
  1174. as the initial boot-console.
  1175. See also comment in drivers/video/console/sticore.c.
  1176. sti_font= [HW]
  1177. See comment in drivers/video/console/sticore.c.
  1178. stifb= [HW]
  1179. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1180. swiotlb= [IA-64] Number of I/O TLB slabs
  1181. switches= [HW,M68k]
  1182. sym53c416= [HW,SCSI]
  1183. See header of drivers/scsi/sym53c416.c.
  1184. t128= [HW,SCSI]
  1185. See header of drivers/scsi/t128.c.
  1186. tdfx= [HW,DRM]
  1187. thash_entries= [KNL,NET]
  1188. Set number of hash buckets for TCP connection
  1189. time Show timing data prefixed to each printk message line
  1190. tipar.timeout= [HW,PPT]
  1191. Set communications timeout in tenths of a second
  1192. (default 15).
  1193. tipar.delay= [HW,PPT]
  1194. Set inter-bit delay in microseconds (default 10).
  1195. tmc8xx= [HW,SCSI]
  1196. See header of drivers/scsi/seagate.c.
  1197. tmscsim= [HW,SCSI]
  1198. See comment before function dc390_setup() in
  1199. drivers/scsi/tmscsim.c.
  1200. tp720= [HW,PS2]
  1201. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1202. Format:
  1203. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1204. tsdev.xres= [TS] Horizontal screen resolution.
  1205. tsdev.yres= [TS] Vertical screen resolution.
  1206. turbografx.map[2|3]= [HW,JOY]
  1207. TurboGraFX parallel port interface
  1208. Format:
  1209. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1210. See also Documentation/input/joystick-parport.txt
  1211. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1212. See header of drivers/scsi/u14-34f.c.
  1213. uart401= [HW,OSS]
  1214. Format: <io>,<irq>
  1215. uart6850= [HW,OSS]
  1216. Format: <io>,<irq>
  1217. usbhid.mousepoll=
  1218. [USBHID] The interval which mice are to be polled at.
  1219. video= [FB] Frame buffer configuration
  1220. See Documentation/fb/modedb.txt.
  1221. vga= [BOOT,IA-32] Select a particular video mode
  1222. See Documentation/i386/boot.txt and
  1223. Documentation/svga.txt.
  1224. Use vga=ask for menu.
  1225. This is actually a boot loader parameter; the value is
  1226. passed to the kernel using a special protocol.
  1227. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1228. size of <nn>. This can be used to increase the
  1229. minimum size (128MB on x86). It can also be used to
  1230. decrease the size and leave more room for directly
  1231. mapped kernel RAM.
  1232. vmhalt= [KNL,S390]
  1233. vmpoff= [KNL,S390]
  1234. waveartist= [HW,OSS]
  1235. Format: <io>,<irq>,<dma>,<dma2>
  1236. wd33c93= [HW,SCSI]
  1237. See header of drivers/scsi/wd33c93.c.
  1238. wd7000= [HW,SCSI]
  1239. See header of drivers/scsi/wd7000.c.
  1240. wdt= [WDT] Watchdog
  1241. See Documentation/watchdog/watchdog.txt.
  1242. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1243. xd_geo= See header of drivers/block/xd.c.
  1244. xirc2ps_cs= [NET,PCMCIA]
  1245. Format:
  1246. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1247. norandmaps Don't use address space randomization
  1248. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
  1249. ______________________________________________________________________
  1250. TODO:
  1251. Add documentation for ALSA options.
  1252. Add more DRM drivers.