kernel-parameters.txt 79 KB

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