kernel-parameters.txt 74.9 KB
Newer Older
1 2
                          Kernel Parameters
                          ~~~~~~~~~~~~~~~~~
L
Linus Torvalds 已提交
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

The following is a consolidated list of the kernel parameters as implemented
(mostly) by the __setup() macro and sorted into English Dictionary order
(defined as ignoring all punctuation and sorting digits before letters in a
case insensitive manner), and with descriptions where known.

Module parameters for loadable modules are specified only as the
parameter name with optional '=' and value as appropriate, such as:

	modprobe usbcore blinkenlights=1

Module parameters for modules that are built into the kernel image
are specified on the kernel command line with the module name plus
'.' plus parameter name, with '=' and value if appropriate, such as:

	usbcore.blinkenlights=1

20 21 22 23 24 25 26
This document may not be entirely up to date and comprehensive. The command
"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
module. Loadable modules, after being loaded into the running kernel, also
reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
parameters may be changed at runtime by the command
"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".

27 28 29 30
The parameters listed below are only valid if certain kernel build options were
enabled and if respective hardware is present. The text in square brackets at
the beginning of each description states the restrictions within which a
parameter is applicable:
L
Linus Torvalds 已提交
31 32

	ACPI	ACPI support is enabled.
C
Chuck Ebbert 已提交
33
	AGP	AGP (Accelerated Graphics Port) is enabled.
L
Linus Torvalds 已提交
34 35 36
	ALSA	ALSA sound support is enabled.
	APIC	APIC support is enabled.
	APM	Advanced Power Management support is enabled.
H
Haavard Skinnemoen 已提交
37
	AVR32	AVR32 architecture is enabled.
L
Linus Torvalds 已提交
38
	AX25	Appropriate AX.25 support is enabled.
39
	BLACKFIN Blackfin architecture is enabled.
R
Randy Dunlap 已提交
40
	DRM	Direct Rendering Management support is enabled.
L
Linus Torvalds 已提交
41 42 43 44 45 46 47
	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled
	EFI	EFI Partitioning (GPT) is enabled
	EIDE	EIDE/ATAPI support is enabled.
	FB	The frame buffer device is enabled.
	HW	Appropriate hardware is enabled.
	IA-64	IA-64 architecture is enabled.
	IOSCHED	More than one I/O scheduler is enabled.
48
	IP_PNP	IP DHCP, BOOTP, or RARP is enabled.
L
Linus Torvalds 已提交
49 50 51
	ISAPNP	ISA PnP code is enabled.
	ISDN	Appropriate ISDN support is enabled.
	JOY	Appropriate joystick support is enabled.
52
	LIBATA  Libata driver is enabled
L
Linus Torvalds 已提交
53 54 55 56 57 58 59 60
	LP	Printer support is enabled.
	LOOP	Loopback device support is enabled.
	M68k	M68k architecture is enabled.
			These options have more detailed description inside of
			Documentation/m68k/kernel-options.txt.
	MCA	MCA bus support is enabled.
	MDA	MDA console support is enabled.
	MOUSE	Appropriate mouse support is enabled.
61
	MSI	Message Signaled Interrupts (PCI).
62
	MTD	MTD (Memory Technology Device) support is enabled.
L
Linus Torvalds 已提交
63 64
	NET	Appropriate network support is enabled.
	NUMA	NUMA support is enabled.
65
	GENERIC_TIME The generic timeofday code is enabled.
L
Linus Torvalds 已提交
66 67
	NFS	Appropriate NFS support is enabled.
	OSS	OSS sound support is enabled.
68 69
	PV_OPS	A paravirtualized kernel is enabled.
	PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.
L
Linus Torvalds 已提交
70 71
	PARISC	The PA-RISC architecture is enabled.
	PCI	PCI bus support is enabled.
R
Randy Dunlap 已提交
72
	PCIE	PCI Express support is enabled.
L
Linus Torvalds 已提交
73 74 75 76 77 78
	PCMCIA	The PCMCIA subsystem is enabled.
	PNP	Plug & Play support is enabled.
	PPC	PowerPC architecture is enabled.
	PPT	Parallel port support is enabled.
	PS2	Appropriate PS/2 support is enabled.
	RAM	RAM disk support is enabled.
79
	ROOTPLUG The example Root Plug LSM is enabled.
L
Linus Torvalds 已提交
80 81 82 83
	S390	S390 architecture is enabled.
	SCSI	Appropriate SCSI support is enabled.
			A lot of drivers has their options described inside of
			Documentation/scsi/.
84
	SECURITY Different security models are enabled.
L
Linus Torvalds 已提交
85 86
	SELINUX SELinux support is enabled.
	SERIAL	Serial support is enabled.
87
	SH	SuperH architecture is enabled.
L
Linus Torvalds 已提交
88 89
	SMP	The kernel is an SMP kernel.
	SPARC	Sparc architecture is enabled.
D
David Brownell 已提交
90 91
	SWSUSP	Software suspend (hibernation) is enabled.
	SUSPEND	System suspend states are enabled.
L
Linus Torvalds 已提交
92 93 94 95 96 97 98 99
	TS	Appropriate touchscreen support is enabled.
	USB	USB support is enabled.
	USBHID	USB Human Interface Device support is enabled.
	V4L	Video For Linux support is enabled.
	VGA	The VGA console has been enabled.
	VT	Virtual terminal support is enabled.
	WDT	Watchdog support is enabled.
	XT	IBM PC/XT MFM hard disk support is enabled.
100
	X86-32	X86-32, aka i386 architecture is enabled.
L
Linus Torvalds 已提交
101 102
	X86-64	X86-64 architecture is enabled.
			More X86-64 boot options can be found in
U
Uwe Hermann 已提交
103
			Documentation/x86/x86_64/boot-options.txt .
104
	X86	Either 32bit or 64bit x86 (same as X86-32+X86-64)
L
Linus Torvalds 已提交
105 106 107 108 109 110 111 112 113 114

In addition, the following text indicates that the option:

	BUGS=	Relates to possible processor bugs on the said processor.
	KNL	Is a kernel start-up parameter.
	BOOT	Is a boot loader parameter.

Parameters denoted with BOOT are actually interpreted by the boot
loader, and have no meaning to the kernel directly.
Do not modify the syntax of boot loader parameters without extreme
U
Uwe Hermann 已提交
115
need or coordination with <Documentation/x86/i386/boot.txt>.
L
Linus Torvalds 已提交
116

117
There are also arch-specific kernel-parameters not documented here.
U
Uwe Hermann 已提交
118
See for example <Documentation/x86/x86_64/boot-options.txt>.
119

L
Linus Torvalds 已提交
120 121 122 123 124 125
Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
a trailing = on the name of any parameter states that that parameter will
be entered as an environment variable, whereas its absence indicates that
it will appear as a kernel argument readable via /proc/cmdline by programs
running once the system is up.

126 127 128 129 130 131 132
The number of kernel parameters is not limited, but the length of the
complete command line (parameters including spaces etc.) is limited to
a fixed number of characters. This limit depends on the architecture
and is between 256 and 4096 characters. It is defined in the file
./include/asm/setup.h as COMMAND_LINE_SIZE.


133 134
	acpi=		[HW,ACPI,X86-64,i386]
			Advanced Configuration and Power Interface
R
Randy Dunlap 已提交
135
			Format: { force | off | ht | strict | noirq }
L
Linus Torvalds 已提交
136 137 138 139
			force -- enable ACPI if default was off
			off -- disable ACPI if default was on
			noirq -- do not use ACPI for IRQ routing
			ht -- run only enough ACPI to enable Hyper Threading
R
Randy Dunlap 已提交
140
			strict -- Be less tolerant of platforms that are not
L
Linus Torvalds 已提交
141 142
				strictly ACPI specification compliant.

143
			See also Documentation/power/pm.txt, pci=noacpi
L
Linus Torvalds 已提交
144

L
Len Brown 已提交
145 146 147 148
	acpi_apic_instance=	[ACPI, IOAPIC]
			Format: <int>
			2: use 2nd APIC table, if available
			1,0: use 1st APIC table
149
			default: 0
L
Len Brown 已提交
150

L
Linus Torvalds 已提交
151
	acpi_sleep=	[HW,ACPI] Sleep options
152 153
			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
				  old_ordering, s4_nonvs }
P
Pavel Machek 已提交
154 155 156
			See Documentation/power/video.txt for s3_bios and s3_mode.
			s3_beep is for debugging; it makes the PC's speaker beep
			as soon as the kernel's real-mode entry point is called.
157 158
			s4_nohwsig prevents ACPI hardware signature from being
			used during resume from hibernation.
159 160 161 162
			old_ordering causes the ACPI 1.0 ordering of the _PTS
			control method, wrt putting devices into low power
			states, to be enforced (the ACPI 2.0 ordering of _PTS is
			used by default).
163 164
			s4_nonvs prevents the kernel from saving/restoring the
			ACPI NVS memory during hibernation.
R
Randy Dunlap 已提交
165

L
Linus Torvalds 已提交
166
	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
R
Randy Dunlap 已提交
167
			Format: { level | edge | high | low }
L
Linus Torvalds 已提交
168

R
Randy Dunlap 已提交
169 170 171
	acpi_irq_balance [HW,ACPI]
			ACPI will balance active IRQs
			default in APIC mode
L
Linus Torvalds 已提交
172

R
Randy Dunlap 已提交
173 174 175
	acpi_irq_nobalance [HW,ACPI]
			ACPI will not move active IRQs (default)
			default in PIC mode
L
Linus Torvalds 已提交
176

R
Randy Dunlap 已提交
177 178
	acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
			use by PCI
L
Linus Torvalds 已提交
179 180
			Format: <irq>,<irq>...

R
Randy Dunlap 已提交
181
	acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
L
Linus Torvalds 已提交
182 183
			Format: <irq>,<irq>...

184 185
	acpi_no_auto_ssdt	[HW,ACPI] Disable automatic loading of SSDT

186 187 188
	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
			Format: To spoof as Windows 98: ="Microsoft Windows"

L
Len Brown 已提交
189 190 191 192
	acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
			acpi_osi="string1"	# add string1 -- only one string
			acpi_osi="!string2"	# remove built-in string2
			acpi_osi=		# disable all strings
L
Linus Torvalds 已提交
193 194 195 196 197 198

	acpi_serialize	[HW,ACPI] force serialization of AML methods

	acpi_skip_timer_override [HW,ACPI]
			Recognize and ignore IRQ0/pin2 Interrupt Override.
			For broken nForce2 BIOS resulting in XT-PIC timer.
199 200 201 202
	acpi_use_timer_override [HW,ACPI}
			Use timer override. For some broken Nvidia NF5 boards
			that require a timer override, but don't have
			HPET
L
Linus Torvalds 已提交
203

204 205 206 207 208 209 210 211 212 213 214 215
	acpi_backlight=	[HW,ACPI]
			acpi_backlight=vendor
			acpi_backlight=video
			If set to vendor, prefer vendor specific driver
			(e.g. thinkpad_acpi, sony_acpi, etc.) instead
			of the ACPI video.ko driver.

	acpi_display_output=	[HW,ACPI]
			acpi_display_output=vendor
			acpi_display_output=video
			See above.

216 217
	acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
	acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
L
Linus Torvalds 已提交
218
			Format: <int>
219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239
			CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
			debug output.  Bits in debug_layer correspond to a
			_COMPONENT in an ACPI source file, e.g.,
			    #define _COMPONENT ACPI_PCI_COMPONENT
			Bits in debug_level correspond to a level in
			ACPI_DEBUG_PRINT statements, e.g.,
			    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
			See Documentation/acpi/debug.txt for more information
			about debug layers and levels.

			Enable AML "Debug" output, i.e., stores to the Debug
			object while interpreting AML:
			    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
			Enable PCI/PCI interrupt routing info messages:
			    acpi.debug_layer=0x400000 acpi.debug_level=0x4
			Enable all messages related to ACPI hardware:
			    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff

			Some values produce so much output that the system is
			unusable.  The "log_buf_len" parameter may be useful
			if you need to capture more output.
240

241 242 243 244 245 246 247 248
 	acpi.power_nocheck=	[HW,ACPI]
 			Format: 1/0 enable/disable the check of power state.
 			On some bogus BIOS the _PSC object/_STA object of
 			power resource can't return the correct device power
 			state. In such case it is unneccessary to check its
 			power state again in power transition.
 			1 : disable the power state check

249
	acpi_pm_good	[X86-32,X86-64]
250 251 252 253
			Override the pmtimer bug detection: force the kernel
			to assume that this machine's pmtimer latches its value
			and always returns good values.

C
Chuck Ebbert 已提交
254 255 256 257 258 259
	agp=		[AGP]
			{ off | try_unsupported }
			off: disable AGP support
			try_unsupported: try to drive unsupported chipsets
				(may crash computer or cause data corruption)

260 261
	enable_timer_pin_1 [i386,x86-64]
			Enable PIN 1 of APIC timer
R
Randy Dunlap 已提交
262 263
			Can be useful to work around chipset bugs
			(in particular on some ATI chipsets).
264 265 266 267 268 269
			The kernel tries to set a reasonable default.

	disable_timer_pin_1 [i386,x86-64]
			Disable PIN 1 of APIC timer
			Can be useful to work around chipset bugs.

L
Linus Torvalds 已提交
270 271 272 273 274 275 276 277 278 279 280 281
	ad1848=		[HW,OSS]
			Format: <io>,<irq>,<dma>,<dma2>,<type>

	advansys=	[HW,SCSI]
			See header of drivers/scsi/advansys.c.

	advwdt=		[HW,WDT] Advantech WDT
			Format: <iostart>,<iostop>

	aedsp16=	[HW,OSS] Audio Excel DSP 16
			Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
			See also header of sound/oss/aedsp16.c.
R
Randy Dunlap 已提交
282

L
Linus Torvalds 已提交
283 284 285 286 287 288 289 290 291 292 293 294
	aha152x=	[HW,SCSI]
			See Documentation/scsi/aha152x.txt.

	aha1542=	[HW,SCSI]
			Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]

	aic7xxx=	[HW,SCSI]
			See Documentation/scsi/aic7xxx.txt.

	aic79xx=	[HW,SCSI]
			See Documentation/scsi/aic79xx.txt.

295 296 297 298 299
	amd_iommu=	[HW,X86-84]
			Pass parameters to the AMD IOMMU driver in the system.
			Possible values are:
			isolate - enable device isolation (each device, as far
			          as possible, will get its own protection
300
			          domain) [default]
301 302
			share - put every device behind one IOMMU into the
				same protection domain
303 304 305 306 307
			fullflush - enable flushing of IO/TLB entries when
				    they are unmapped. Otherwise they are
				    flushed before they will be reused, which
				    is a lot of faster

308 309 310 311 312
	amd_iommu_size= [HW,X86-64]
			Define the size of the aperture for the AMD IOMMU
			driver. Possible values are:
			'32M', '64M' (default), '128M', '256M', '512M', '1G'

L
Linus Torvalds 已提交
313 314 315 316 317 318 319 320 321 322
	amijoy.map=	[HW,JOY] Amiga joystick support
			Map of devices attached to JOY0DAT and JOY1DAT
			Format: <a>,<b>
			See also Documentation/kernel/input/joystick.txt

	analog.map=	[HW,JOY] Analog joystick and gamepad support
			Specifies type or capabilities of an analog joystick
			connected to one of 16 gameports
			Format: <type1>,<type2>,..<type16>

R
Randy Dunlap 已提交
323 324
	apc=		[HW,SPARC]
			Power management functions (SPARCstation-4/5 + deriv.)
L
Linus Torvalds 已提交
325 326 327 328 329
			Format: noidle
			Disable APC CPU standby support. SPARCstation-Fox does
			not play well with APC CPU idle - disable it if you have
			APC and your system crashes randomly.

330 331
	apic=		[APIC,i386] Advanced Programmable Interrupt Controller
			Change the output verbosity whilst booting
L
Linus Torvalds 已提交
332 333 334
			Format: { quiet (default) | verbose | debug }
			Change the amount of debugging information output
			when initialising the APIC and IO-APIC components.
R
Randy Dunlap 已提交
335

L
Linus Torvalds 已提交
336
	apm=		[APM] Advanced Power Management
337
			See header of arch/x86/kernel/apm_32.c.
L
Linus Torvalds 已提交
338 339 340 341 342 343 344 345 346 347 348 349 350 351 352

	arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
			Format: <io>,<irq>,<nodeID>

	ataflop=	[HW,M68k]

	atarimouse=	[HW,MOUSE] Atari Mouse

	atascsi=	[HW,SCSI] Atari SCSI

	atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
			EzKey and similar keyboards

	atkbd.reset=	[HW] Reset keyboard during initialization

R
Randy Dunlap 已提交
353 354
	atkbd.set=	[HW] Select keyboard code set
			Format: <int> (2 = AT (default), 3 = PS/2)
L
Linus Torvalds 已提交
355 356 357 358 359 360

	atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
			keyboards

	atkbd.softraw=	[HW] Choose between synthetic and real raw mode
			Format: <bool> (0 = real, 1 = synthetic (default))
R
Randy Dunlap 已提交
361 362 363

	atkbd.softrepeat= [HW]
			Use software keyboard repeat
L
Linus Torvalds 已提交
364 365 366 367 368

	autotest	[IA64]

	baycom_epp=	[HW,AX25]
			Format: <io>,<mode>
R
Randy Dunlap 已提交
369

L
Linus Torvalds 已提交
370 371 372 373
	baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
			Format: <io>,<mode>
			See header of drivers/net/hamradio/baycom_par.c.

R
Randy Dunlap 已提交
374 375
	baycom_ser_fdx=	[HW,AX25]
			BayCom Serial Port AX.25 Modem (Full Duplex Mode)
L
Linus Torvalds 已提交
376 377 378
			Format: <io>,<irq>,<mode>[,<baud>]
			See header of drivers/net/hamradio/baycom_ser_fdx.c.

R
Randy Dunlap 已提交
379 380
	baycom_ser_hdx=	[HW,AX25]
			BayCom Serial Port AX.25 Modem (Half Duplex Mode)
L
Linus Torvalds 已提交
381 382 383
			Format: <io>,<irq>,<mode>
			See header of drivers/net/hamradio/baycom_ser_hdx.c.

R
Randy Dunlap 已提交
384 385 386 387 388
	boot_delay=	Milliseconds to delay each printk during boot.
			Values larger than 10 seconds (10000) are changed to
			no delay (0).
			Format: integer

389 390
	bootmem_debug	[KNL] Enable bootmem allocator debug messages.

L
Linus Torvalds 已提交
391
	bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
R
Randy Dunlap 已提交
392 393
	bttv.radio=	Most important insmod options are available as
			kernel args too.
L
Linus Torvalds 已提交
394 395 396 397 398 399 400 401 402
	bttv.pll=	See Documentation/video4linux/bttv/Insmod-options
	bttv.tuner=	and Documentation/video4linux/bttv/CARDLIST

	BusLogic=	[HW,SCSI]
			See drivers/scsi/BusLogic.c, comment before function
			BusLogic_ParseDriverOptions().

	c101=		[NET] Moxa C101 synchronous serial card

403
	cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
L
Linus Torvalds 已提交
404 405 406 407 408 409
			Sometimes CPU hardware bugs make them report the cache
			size incorrectly. The kernel will attempt work arounds
			to fix known problems, but for some CPUs it is not
			possible to determine what the correct size should be.
			This option provides an override for these situations.

410 411 412 413 414 415
	security=	[SECURITY] Choose a security module to enable at boot.
			If this boot parameter is not specified, only the first
			security module asking for security registration will be
			loaded. An invalid security module name will be treated
			as if no module has been chosen.

416 417 418 419 420 421
	capability.disable=
			[SECURITY] Disable capabilities.  This would normally
			be used only if an alternative security model is to be
			configured.  Potentially dangerous and should only be
			used if you are entirely sure of the consequences.

422 423
	ccw_timeout_log [S390]
			See Documentation/s390/CommonIO for details.
L
Linus Torvalds 已提交
424

425 426 427 428
	cgroup_disable= [KNL] Disable a particular controller
			Format: {name of the controller(s) to disable}
				{Currently supported controllers - "memory"}

L
Linus Torvalds 已提交
429 430 431
	checkreqprot	[SELINUX] Set initial checkreqprot flag value.
			Format: { "0" | "1" }
			See security/selinux/Kconfig help text.
R
Randy Dunlap 已提交
432 433
			0 -- check protection applied by kernel (includes
				any implied execute protection).
L
Linus Torvalds 已提交
434 435
			1 -- check protection requested by application.
			Default value is set via a kernel config option.
R
Randy Dunlap 已提交
436 437 438
			Value can be changed at runtime via
				/selinux/checkreqprot.

439 440 441
	cio_ignore=	[S390]
			See Documentation/s390/CommonIO for details.

442
	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
443
			[Deprecated]
444
			Forces specified clocksource (if available) to be used
445
			when calculating gettimeofday(). If specified
446
			clocksource is not available, it defaults to PIT.
L
Linus Torvalds 已提交
447 448
			Format: { pit | tsc | cyclone | pmtmr }

R
Randy Dunlap 已提交
449 450 451 452 453 454 455 456 457 458 459
	clocksource=	[GENERIC_TIME] Override the default clocksource
			Format: <string>
			Override the default clocksource and use the clocksource
			with the name specified.
			Some clocksource names to choose from, depending on
			the platform:
			[all] jiffies (this is the base, fallback clocksource)
			[ACPI] acpi_pm
			[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
				pxa_timer,timer3,32k_counter,timer0_1
			[AVR32] avr32
460
			[X86-32] pit,hpet,tsc,vmi-timer;
R
Randy Dunlap 已提交
461 462 463 464 465 466 467 468
				scx200_hrt on Geode; cyclone on IBM x440
			[MIPS] MIPS
			[PARISC] cr16
			[S390] tod
			[SH] SuperH
			[SPARC64] tick
			[X86-64] hpet,tsc

469 470 471 472 473 474 475 476 477 478 479 480 481
	clearcpuid=BITNUM [X86]
			Disable CPUID feature X for the kernel. See
			include/asm-x86/cpufeature.h for the valid bit numbers.
			Note the Linux specific bits are not necessarily
			stable over kernel options, but the vendor specific
			ones should be.
			Also note that user programs calling CPUID directly
			or using the feature without checking anything
			will still see it. This just prevents it from
			being used by the kernel or shown in /proc/cpuinfo.
			Also note the kernel might malfunction if you disable
			some critical bits.

482 483
	code_bytes	[IA32/X86_64] How many bytes of object code to print
			in an oops report.
484 485 486
			Range: 0 - 8192
			Default: 64

T
Thomas Gleixner 已提交
487 488 489
	hpet=		[X86-32,HPET] option to control HPET usage
			Format: { enable (default) | disable | force }
			disable: disable HPET and use PIT instead
490 491
			force: allow force enabled of undocumented chips (ICH4,
			VIA, nVidia)
L
Linus Torvalds 已提交
492 493

	com20020=	[HW,NET] ARCnet - COM20020 chipset
R
Randy Dunlap 已提交
494 495
			Format:
			<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
L
Linus Torvalds 已提交
496 497 498 499

	com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
			Format: <io>[,<irq>]

R
Randy Dunlap 已提交
500 501
	com90xx=	[HW,NET]
			ARCnet - COM90xx chipset (memory-mapped buffers)
L
Linus Torvalds 已提交
502 503 504 505
			Format: <io>[,<irq>[,<memstart>]]

	condev=		[HW,S390] console device
	conmode=
R
Randy Dunlap 已提交
506

L
Linus Torvalds 已提交
507 508 509 510 511
	console=	[KNL] Output console device and options.

		tty<n>	Use the virtual console device <n>.

		ttyS<n>[,options]
512
		ttyUSB0[,options]
L
Linus Torvalds 已提交
513
			Use the specified serial port.  The options are of
514 515 516 517 518 519 520 521 522
			the form "bbbbpnf", where "bbbb" is the baud rate,
			"p" is parity ("n", "o", or "e"), "n" is number of
			bits, and "f" is flow control ("r" for RTS or
			omit it).  Default is "9600n8".

			See Documentation/serial-console.txt for more
			information.  See
			Documentation/networking/netconsole.txt for an
			alternative.
L
Linus Torvalds 已提交
523

524 525
		uart[8250],io,<addr>[,options]
		uart[8250],mmio,<addr>[,options]
L
Linus Torvalds 已提交
526 527 528 529 530
			Start an early, polled-mode console on the 8250/16550
			UART at the specified I/O port or MMIO address,
			switching to the matching ttyS device later.  The
			options are the same as for ttyS, above.

531 532 533 534 535
                If the device connected to the port is not a TTY but a braille
                device, prepend "brl," before the device type, for instance
			console=brl,ttyS0
		For now, only VisioBraille is supported.

536 537 538 539 540 541 542
	earlycon=	[KNL] Output early console device and options.
		uart[8250],io,<addr>[,options]
		uart[8250],mmio,<addr>[,options]
			Start an early, polled-mode console on the 8250/16550
			UART at the specified I/O port or MMIO address.
			The options are the same as for ttyS, above.

543 544 545 546 547 548 549 550 551 552
	no_console_suspend
			[HW] Never suspend the console
			Disable suspending of consoles during suspend and
			hibernate operations.  Once disabled, debugging
			messages can reach various consoles while the rest
			of the system is being put to sleep (ie, while
			debugging driver suspend/resume hooks).  This may
			not work reliably with all consoles, but is known
			to work with serial and VGA consoles.

L
Linus Torvalds 已提交
553
	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
R
Randy Dunlap 已提交
554 555
			Format:
			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
L
Linus Torvalds 已提交
556

557 558 559 560
	crashkernel=nn[KMG]@ss[KMG]
			[KNL] Reserve a chunk of physical memory to
			hold a kernel to switch to with kexec on panic.

561 562 563 564 565 566 567
	crashkernel=range1:size1[,range2:size2,...][@offset]
			[KNL] Same as above, but depends on the memory
			in the running system. The syntax of range is
			start-[end] where start and end are both
			a memory unit (amount[KMG]). See also
			Documentation/kdump/kdump.txt for a example.

L
Linus Torvalds 已提交
568 569 570 571 572 573 574 575
	cs4232=		[HW,OSS]
			Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>

	cs89x0_dma=	[HW,NET]
			Format: <dma>

	cs89x0_media=	[HW,NET]
			Format: { rj45 | aui | bnc }
R
Randy Dunlap 已提交
576 577

	dasd=		[HW,NET]
L
Linus Torvalds 已提交
578 579 580 581 582 583 584 585 586
			See header of drivers/s390/block/dasd_devmap.c.

	db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
			(one device per port)
			Format: <port#>,<type>
			See also Documentation/input/joystick-parport.txt

	debug		[KNL] Enable kernel debugging (events log level).

587 588 589 590 591 592 593 594 595
	debug_locks_verbose=
			[KNL] verbose self-tests
			Format=<0|1>
			Print debugging info while doing the locking API
			self-tests.
			We default to 0 (no extra messages), setting it to
			1 will print _a lot_ more information - normally
			only useful to kernel developers.

596 597
	debug_objects	[KNL] Enable object debugging

598 599
	debugpat	[X86] Enable PAT debugging

600
	decnet.addr=	[HW,NET]
L
Linus Torvalds 已提交
601 602 603
			Format: <area>[,<node>]
			See also Documentation/networking/decnet.txt.

S
Samuel Thibault 已提交
604
	vt.default_blu=	[VT]
605 606 607 608 609
			Format: <blue0>,<blue1>,<blue2>,...,<blue15>
			Change the default blue palette of the console.
			This is a 16-member array composed of values
			ranging from 0-255.

S
Samuel Thibault 已提交
610
	vt.default_grn=	[VT]
611 612 613 614 615
			Format: <green0>,<green1>,<green2>,...,<green15>
			Change the default green palette of the console.
			This is a 16-member array composed of values
			ranging from 0-255.

S
Samuel Thibault 已提交
616
	vt.default_red=	[VT]
617 618 619 620 621
			Format: <red0>,<red1>,<red2>,...,<red15>
			Change the default red palette of the console.
			This is a 16-member array composed of values
			ranging from 0-255.

S
Samuel Thibault 已提交
622 623
	vt.default_utf8=
			[VT]
624 625
			Format=<0|1>
			Set system-wide default UTF-8 mode for all tty's.
S
Samuel Thibault 已提交
626 627
			Default is 1, i.e. UTF-8 mode is enabled for all
			newly opened terminals.
628

L
Linus Torvalds 已提交
629 630
	dhash_entries=	[KNL]
			Set number of hash buckets for dentry cache.
R
Randy Dunlap 已提交
631

L
Linus Torvalds 已提交
632 633 634 635 636
	digi=		[HW,SERIAL]
			IO parameters + enable/disable command.

	digiepca=	[HW,SERIAL]
			See drivers/char/README.epca and
637
			Documentation/serial/digiepca.txt.
L
Linus Torvalds 已提交
638

639 640 641 642 643 644 645 646 647 648 649
	disable_mtrr_cleanup [X86]
	enable_mtrr_cleanup [X86]
			The kernel tries to adjust MTRR layout from continuous
			to discrete, to make X server driver able to add WB
			entry later. This parameter enables/disables that.

	mtrr_chunk_size=nn[KMG] [X86]
			used for mtrr cleanup. It is largest continous chunk
			that could hold holes aka. UC entries.

	mtrr_gran_size=nn[KMG] [X86]
650 651 652 653 654 655 656 657 658 659 660
			Used for mtrr cleanup. It is granularity of mtrr block.
			Default is 1.
			Large value could prevent small alignment from
			using up MTRRs.

	mtrr_spare_reg_nr=n [X86]
			Format: <integer>
			Range: 0,7 : spare reg number
			Default : 1
			Used for mtrr cleanup. It is spare mtrr entries number.
			Set to 2 or more if your graphical card needs more.
661

662
	disable_mtrr_trim [X86, Intel and AMD only]
663 664 665 666 667
			By default the kernel will trim any uncacheable
			memory out of your available memory pool based on
			MTRR settings.  This parameter disables that behavior,
			possibly causing your machine to run very slowly.

L
Linus Torvalds 已提交
668 669 670 671 672 673
	dmasound=	[HW,OSS] Sound subsystem buffers

	dscc4.setup=	[NET]

	dtc3181e=	[HW,SCSI]

674
	earlyprintk=	[X86-32,X86-64,SH,BLACKFIN]
L
Linus Torvalds 已提交
675 676
			earlyprintk=vga
			earlyprintk=serial[,ttySn[,baudrate]]
677
			earlyprintk=dbgp
L
Linus Torvalds 已提交
678

R
Randy Dunlap 已提交
679
			Append ",keep" to not disable it when the real console
L
Linus Torvalds 已提交
680 681
			takes over.

682
			Only vga or serial or usb debug port at a time.
L
Linus Torvalds 已提交
683 684 685 686 687 688 689 690 691 692 693 694

			Currently only ttyS0 and ttyS1 are supported.

			Interaction with the standard serial driver is not
			very good.

			The VGA output is eventually overwritten by the real
			console.

	eata=		[HW,SCSI]

	edd=		[EDD]
695
			Format: {"off" | "on" | "skip[mbr]"}
L
Linus Torvalds 已提交
696 697 698 699

	eisa_irq_edge=	[PARISC,HW]
			See header of drivers/parisc/eisa.c.

700
	elanfreq=	[X86-32]
L
Linus Torvalds 已提交
701
			See comment before function elanfreq_setup() in
702
			arch/x86/kernel/cpu/cpufreq/elanfreq.c.
L
Linus Torvalds 已提交
703 704

	elevator=	[IOSCHED]
705
			Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
R
Randy Dunlap 已提交
706 707 708
			See Documentation/block/as-iosched.txt and
			Documentation/block/deadline-iosched.txt for details.

709
	elfcorehdr=	[IA64,PPC,SH,X86-32,X86_64]
R
Randy Dunlap 已提交
710
			Specifies physical address of start of kernel core
711 712 713
			image elf header. Generally kexec loader will
			pass this option to capture kernel.
			See Documentation/kdump/kdump.txt for details.
L
Linus Torvalds 已提交
714 715 716 717 718 719 720 721 722 723 724 725

	enforcing	[SELINUX] Set initial enforcing status.
			Format: {"0" | "1"}
			See security/selinux/Kconfig help text.
			0 -- permissive (log only, no denials).
			1 -- enforcing (deny and log).
			Default value is 0.
			Value can be changed at runtime via /selinux/enforce.

	es1371=		[HW,OSS]
			Format: <spdif>,[<nomix>,[<amplifier>]]
			See also header of sound/oss/es1371.c.
R
Randy Dunlap 已提交
726

L
Linus Torvalds 已提交
727 728 729 730 731 732 733
	ether=		[HW,NET] Ethernet cards parameters
			This option is obsoleted by the "netdev=" option, which
			has equivalent usage. See its documentation for details.

	eurwdt=		[HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
			Format: <io>[,<irq>]

734 735 736 737 738 739 740
	failslab=
	fail_page_alloc=
	fail_make_request=[KNL]
			General fault injection mechanism.
			Format: <interval>,<probability>,<space>,<times>
			See also /Documentation/fault-injection/.

L
Linus Torvalds 已提交
741 742 743 744 745 746 747
	fd_mcs=		[HW,SCSI]
			See header of drivers/scsi/fd_mcs.c.

	fdomain=	[HW,SCSI]
			See header of drivers/scsi/fdomain.c.

	floppy=		[HW]
748
			See Documentation/blockdev/floppy.txt.
L
Linus Torvalds 已提交
749

750 751 752 753 754 755
	force_pal_cache_flush
			[IA-64] Avoid check_sal_cache_flush which may hang on
			buggy SAL_CACHE_FLUSH implementations. Using this
			parameter will force ia64_sal_cache_flush to call
			ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.

L
Linus Torvalds 已提交
756 757 758 759 760 761 762 763
	gamecon.map[2|3]=
			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
			support via parallel port (up to 5 devices per port)
			Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
			See also Documentation/input/joystick-parport.txt

	gamma=		[HW,DRM]

Y
Yinghai Lu 已提交
764 765 766 767
	gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
			Format: off | on
			default: on

L
Linus Torvalds 已提交
768 769 770 771 772 773 774 775 776 777 778
	gdth=		[HW,SCSI]
			See header of drivers/scsi/gdth.c.

	gpt		[EFI] Forces disk with valid GPT signature but
			invalid Protective MBR to be treated as GPT.

	gvp11=		[HW,SCSI]

	hashdist=	[KNL,NUMA] Large hashes allocated during boot
			are distributed across NUMA nodes.  Defaults on
			for IA-64, off otherwise.
R
Randy Dunlap 已提交
779
			Format: 0 | 1 (for off | on)
L
Linus Torvalds 已提交
780 781 782 783 784 785 786 787 788 789 790

	hcl=		[IA-64] SGI's Hardware Graph compatibility layer

	hd=		[EIDE] (E)IDE hard drive subsystem geometry
			Format: <cyl>,<head>,<sect>

	highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
			size of <nn>. This works even on boxes that have no
			highmem otherwise. This also works to reduce highmem
			size on bigger boxes.

791 792 793 794
	highres=	[KNL] Enable/disable high resolution timer mode.
			Valid parameters: "on", "off"
			Default: "on"

L
Linus Torvalds 已提交
795 796 797
	hisax=		[HW,ISDN]
			See Documentation/isdn/README.HiSax.

798 799
	hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
	hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
800 801 802 803 804
			On x86-64 and powerpc, this option can be specified
			multiple times interleaved with hugepages= to reserve
			huge pages of different sizes. Valid pages sizes on
			x86-64 are 2M (when the CPU supports "pse") and 1G
			(when the CPU supports the "pdpe1gb" cpuinfo flag)
805 806
			Note that 1GB pages can only be allocated at boot time
			using hugepages= and not freed afterwards.
807 808 809 810 811 812 813
	default_hugepagesz=
			[same as hugepagesz=] The size of the default
			HugeTLB page size. This is the size represented by
			the legacy /proc/ hugepages APIs, used for SHM, and
			default size when mounting hugetlbfs filesystems.
			Defaults to the default architecture's huge page size
			if not specified.
L
Linus Torvalds 已提交
814

815 816
	hlt		[BUGS=ARM,SH]

817
	i8042.debug	[HW] Toggle i8042 debug mode
L
Linus Torvalds 已提交
818
	i8042.direct	[HW] Put keyboard port into non-translated mode
819 820
	i8042.dumbkbd	[HW] Pretend that controller can only read data from
			     keyboard and cannot control its state
L
Linus Torvalds 已提交
821 822
			     (Don't attempt to blink the leds)
	i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
823
	i8042.nokbd	[HW] Don't check/create keyboard port
J
Jiri Kosina 已提交
824 825
	i8042.noloop	[HW] Disable the AUX Loopback command while probing
			     for the AUX port
L
Linus Torvalds 已提交
826 827 828 829 830 831 832 833 834 835 836 837
	i8042.nomux	[HW] Don't check presence of an active multiplexing
			     controller
	i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
			     controllers
	i8042.panicblink=
			[HW] Frequency with which keyboard LEDs should blink
			     when kernel panics (default is 0.5 sec)
	i8042.reset	[HW] Reset the controller during init and cleanup
	i8042.unlock	[HW] Unlock (ignore) the keylock

	i810=		[HW,DRM]

838 839 840
	i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
			indicates that the driver is running on unsupported
			hardware.
L
Linus Torvalds 已提交
841 842 843 844 845 846 847 848 849 850 851 852 853 854 855
	i8k.force	[HW] Activate i8k driver even if SMM BIOS signature
			does not match list of supported models.
	i8k.power_status
			[HW] Report power status in /proc/i8k
			(disabled by default)
	i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN
			capability is set.

	ibmmcascsi=	[HW,MCA,SCSI] IBM MicroChannel SCSI adapter
			See Documentation/mca.txt.

	icn=		[HW,ISDN]
			Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]

	ide=		[HW] (E)IDE subsystem
856
			Format: ide=nodma or ide=doubler
857
			See Documentation/ide/ide.txt.
L
Linus Torvalds 已提交
858 859

	idebus=		[HW] (E)IDE subsystem - VLB/PCI bus speed
860
			See Documentation/ide/ide.txt.
L
Linus Torvalds 已提交
861

862
	idle=		[X86]
863
			Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
864 865 866 867 868 869 870
			Poll forces a polling idle loop that can slightly improves the performance
			of waking up a idle CPU, but will use a lot of power and make the system
			run hot. Not recommended.
			idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
			to not use it because it doesn't save as much power as a normal idle
			loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
			as idle=poll.
Z
Zhao Yakui 已提交
871 872
			idle=halt. Halt is forced to be used for CPU idle.
			In such case C2/C3 won't be used again.
873
			idle=nomwait. Disable mwait for CPU C-states
R
Randy Dunlap 已提交
874

875 876 877
	ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
			Claim all unknown PCI IDE storage controllers.

878 879 880 881
	ignore_loglevel	[KNL]
			Ignore loglevel setting - this will print /all/
			kernel messages to the console. Useful for debugging.

L
Linus Torvalds 已提交
882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903
	ihash_entries=	[KNL]
			Set number of hash buckets for inode cache.

	in2000=		[HW,SCSI]
			See header of drivers/scsi/in2000.c.

	init=		[KNL]
			Format: <full_path>
			Run specified binary instead of /sbin/init as init
			process.

	initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
			for working out where the kernel is dying during
			startup.

	initrd=		[BOOT] Specify the location of the initial ramdisk

	inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
			Format: <irq>

	inttest=	[IA64]

P
Pavel Machek 已提交
904 905 906 907 908 909 910 911 912 913 914 915 916
	iommu=		[x86]
		off
		force
		noforce
		biomerge
		panic
		nopanic
		merge
		nomerge
		forcesac
		soft


917 918 919 920 921 922 923 924 925
	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
		off
			Disable intel iommu driver.
		igfx_off [Default Off]
			By default, gfx is mapped as normal device. If a gfx
			device has a dedicated DMAR unit, the DMAR unit is
			bypassed by not enabling DMAR with this option. In
			this case, gfx device will use physical address for
			DMA.
926 927 928 929 930 931 932
		forcedac [x86_64]
			With this option iommu will not optimize to look
			for io virtual address below 32 bit forcing dual
			address cycle on pci bus for cards supporting greater
			than 32 bit addressing. The default is to look
			for translation below 32 bit and if not available
			then look in the higher range.
M
mark gross 已提交
933 934 935 936
		strict [Default Off]
			With this option on every unmap_single operation will
			result in a hardware IOTLB flush operation as opposed
			to batching them for performance.
937

938
	io_delay=	[X86-32,X86-64] I/O delay method
939 940 941 942
		0x80
			Standard port 0x80 based delay
		0xed
			Alternate port 0xed based delay (needed on some systems)
943
		udelay
944 945 946
			Simple two microseconds delay
		none
			No delay
947

L
Linus Torvalds 已提交
948 949 950 951 952
	io7=		[HW] IO7 for Marvel based alpha systems
			See comment before marvel_specify_io7 in
			arch/alpha/kernel/core_marvel.c.

	ip=		[IP_PNP]
953
			See Documentation/filesystems/nfsroot.txt.
L
Linus Torvalds 已提交
954 955

	ip2=		[HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
956 957
			See comment before ip2_setup() in
			drivers/char/ip2/ip2base.c.
L
Linus Torvalds 已提交
958 959 960 961

	ips=		[HW,SCSI] Adaptec / IBM ServeRAID controller
			See header of drivers/scsi/ips.c.

962 963 964 965 966 967
	ports=		[IP_VS_FTP] IPVS ftp helper module
			Default is 21.
			Up to 8 (IP_VS_APP_MAX_PORTS) ports
			may be specified.
			Format: <port>,<port>....

A
Alan Cox 已提交
968 969 970 971 972 973 974 975 976 977 978
	irqfixup	[HW]
			When an interrupt is not handled search all handlers
			for it. Intended to get systems with badly broken
			firmware running.

	irqpoll		[HW]
			When an interrupt is not handled search all handlers
			for it. Also check all handlers each timer
			interrupt. Intended to get systems with badly broken
			firmware running.

L
Linus Torvalds 已提交
979
	isapnp=		[ISAPNP]
R
Randy Dunlap 已提交
980
			Format: <RDP>,<reset>,<pci_scan>,<verbosity>
L
Linus Torvalds 已提交
981 982

	isolcpus=	[KNL,SMP] Isolate CPUs from the general scheduler.
983 984 985
			Format:
			<cpu number>,...,<cpu number>
			or
986 987
			<cpu number>-<cpu number>
			(must be a positive range in ascending order)
988 989
			or a mixture
			<cpu number>,...,<cpu number>-<cpu number>
990

L
Linus Torvalds 已提交
991 992
			This option can be used to specify one or more CPUs
			to isolate from the general SMP balancing and scheduling
993 994
			algorithms. You can move a process onto or off an
			"isolated" CPU via the CPU affinity syscalls or cpuset.
L
Linus Torvalds 已提交
995 996 997 998
			<cpu number> begins at 0 and the maximum value is
			"number of CPUs in system - 1".

			This option is the preferred way to isolate CPUs. The
R
Randy Dunlap 已提交
999 1000 1001
			alternative -- manually setting the CPU mask of all
			tasks in the system -- can cause problems and
			suboptimal load balancer performance.
L
Linus Torvalds 已提交
1002

R
Randy Dunlap 已提交
1003
	iucv=		[HW,NET]
L
Linus Torvalds 已提交
1004 1005 1006 1007

	js=		[HW,JOY] Analog joystick
			See Documentation/input/joystick.txt.

1008
	kernelcore=nn[KMG]	[KNL,X86-32,IA-64,PPC,X86-64] This parameter
M
Mel Gorman 已提交
1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023
			specifies the amount of memory usable by the kernel
			for non-movable allocations.  The requested amount is
			spread evenly throughout all nodes in the system. The
			remaining memory in each node is used for Movable
			pages. In the event, a node is too small to have both
			kernelcore and Movable pages, kernelcore pages will
			take priority and other nodes will have a larger number
			of kernelcore pages.  The Movable zone is used for the
			allocation of pages that may be reclaimed or moved
			by the page migration subsystem.  This means that
			HugeTLB pages may not be allocated from this zone.
			Note that allocations like PTEs-from-HighMem still
			use the HighMem zone if it exists, and the Normal
			zone if it does not.

1024
	movablecore=nn[KMG]	[KNL,X86-32,IA-64,PPC,X86-64] This parameter
1025 1026 1027 1028 1029 1030 1031 1032 1033
			is similar to kernelcore except it specifies the
			amount of memory used for migratable allocations.
			If both kernelcore and movablecore is specified,
			then kernelcore will be at *least* the specified
			value but may be more. If movablecore on its own
			is specified, the administrator must be careful
			that the amount of memory usable for all allocations
			is not too small.

L
Linus Torvalds 已提交
1034 1035
	keepinitrd	[HW,ARM]

1036
	kstack=N	[X86-32,X86-64] Print N words from the kernel stack
L
Linus Torvalds 已提交
1037 1038
			in oops dumps.

J
Jason Wessel 已提交
1039 1040 1041 1042 1043
	kgdboc=		[HW] kgdb over consoles.
			Requires a tty driver that supports console polling.
			(only serial suported for now)
			Format: <serial_device>[,baud]

1044 1045 1046 1047
	kmac=		[MIPS] korina ethernet MAC address.
			Configure the RouterBoard 532 series on-chip
			Ethernet adapter MAC address.

L
Linus Torvalds 已提交
1048 1049
	l2cr=		[PPC]

1050 1051
	l3cr=		[PPC]

1052
	lapic		[X86-32,APIC] Enable the local APIC even if BIOS
R
Randy Dunlap 已提交
1053
			disabled it.
L
Linus Torvalds 已提交
1054

1055
	lapic_timer_c2_ok	[X86-32,x86-64,APIC] trust the local apic timer in
1056 1057
			C2 power state.

1058 1059 1060 1061 1062 1063 1064 1065
	libata.dma=	[LIBATA] DMA control
			libata.dma=0	  Disable all PATA and SATA DMA
			libata.dma=1	  PATA and SATA Disk DMA only
			libata.dma=2	  ATAPI (CDROM) DMA only
			libata.dma=4	  Compact Flash DMA only 
			Combinations also work, so libata.dma=3 enables DMA
			for disks and CDROMs, but not CFs.

1066 1067 1068 1069
	libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
			when set.
			Format: <int>

1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101
	libata.force=	[LIBATA] Force configurations.  The format is comma
			separated list of "[ID:]VAL" where ID is
			PORT[:DEVICE].  PORT and DEVICE are decimal numbers
			matching port, link or device.  Basically, it matches
			the ATA ID string printed on console by libata.  If
			the whole ID part is omitted, the last PORT and DEVICE
			values are used.  If ID hasn't been specified yet, the
			configuration applies to all ports, links and devices.

			If only DEVICE is omitted, the parameter applies to
			the port and all links and devices behind it.  DEVICE
			number of 0 either selects the first device or the
			first fan-out link behind PMP device.  It does not
			select the host link.  DEVICE number of 15 selects the
			host link and device attached to it.

			The VAL specifies the configuration to force.  As long
			as there's no ambiguity shortcut notation is allowed.
			For example, both 1.5 and 1.5G would work for 1.5Gbps.
			The following configurations can be forced.

			* Cable type: 40c, 80c, short40c, unk, ign or sata.
			  Any ID with matching PORT is used.

			* SATA link speed limit: 1.5Gbps or 3.0Gbps.

			* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
			  udma[/][16,25,33,44,66,100,133] notation is also
			  allowed.

			* [no]ncq: Turn on or off NCQ.

1102 1103 1104
			* nohrst, nosrst, norst: suppress hard, soft
                          and both resets.

1105 1106 1107
			If there are multiple matching configurations changing
			the same attribute, the last one is used.

L
Linus Torvalds 已提交
1108
	load_ramdisk=	[RAM] List of ramdisks to load from floppy
1109
			See Documentation/blockdev/ramdisk.txt.
L
Linus Torvalds 已提交
1110

1111 1112
	lockd.nlm_grace_period=P  [NFS] Assign grace period.
			Format: <integer>
L
Linus Torvalds 已提交
1113

1114 1115 1116 1117 1118 1119 1120 1121
	lockd.nlm_tcpport=N	[NFS] Assign TCP port.
			Format: <integer>

	lockd.nlm_timeout=T	[NFS] Assign timeout value.
			Format: <integer>

	lockd.nlm_udpport=M	[NFS] Assign UDP port.
			Format: <integer>
L
Linus Torvalds 已提交
1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140

	logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
			Format: <irq>

	loglevel=	All Kernel Messages with a loglevel smaller than the
			console loglevel will be printed to the console. It can
			also be changed with klogd or other programs. The
			loglevels are defined as follows:

			0 (KERN_EMERG)		system is unusable
			1 (KERN_ALERT)		action must be taken immediately
			2 (KERN_CRIT)		critical conditions
			3 (KERN_ERR)		error conditions
			4 (KERN_WARNING)	warning conditions
			5 (KERN_NOTICE)		normal but significant condition
			6 (KERN_INFO)		informational
			7 (KERN_DEBUG)		debug-level messages

	log_buf_len=n	Sets the size of the printk ring buffer, in bytes.
R
Randy Dunlap 已提交
1141 1142 1143
			Format: { n | nk | nM }
			n must be a power of two.  The default size
			is set in the kernel config file.
L
Linus Torvalds 已提交
1144

R
Randy Dunlap 已提交
1145 1146 1147 1148 1149
	logo.nologo	[FB] Disables display of the built-in Linux logo.
			This may be used to provide more screen space for
			kernel log messages and is useful when debugging
			kernel boot problems.

L
Linus Torvalds 已提交
1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
	lp=0		[LP]	Specify parallel ports to use, e.g,
	lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
	lp=reset		first parallel port). 'lp=0' disables the
	lp=auto			printer driver. 'lp=reset' (which can be
				specified in addition to the ports) causes
				attached printers to be reset. Using
				lp=port1,port2,... specifies the parallel ports
				to associate lp devices with, starting with
				lp0. A port specification may be 'none' to skip
				that lp device, or a parport name such as
				'parport0'. Specifying 'lp=auto' instead of a
				port specification list means that device IDs
				from each port should be examined, to see if
				an IEEE 1284-compliant printer is attached; if
				so, the driver will manage that printer.
				See also header of drivers/char/lp.c.

	lpj=n		[KNL]
			Sets loops_per_jiffy to given constant, thus avoiding
			time-consuming boot-time autodetection (up to 250 ms per
			CPU). 0 enables autodetection (default). To determine
			the correct value for your kernel, boot with normal
			autodetection and see what value is printed. Note that
			on SMP systems the preset will be applied to all CPUs,
			which is likely to cause problems if your CPUs need
			significantly divergent settings. An incorrect value
			will cause delays in the kernel to be wrong, leading to
			unpredictable I/O errors and other breakage. Although
			unlikely, in the extreme case this might damage your
			hardware.

	ltpc=		[NET]
			Format: <io>,<irq>,<dma>

R
Randy Dunlap 已提交
1184 1185
	mac5380=	[HW,SCSI] Format:
			<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
L
Linus Torvalds 已提交
1186

R
Randy Dunlap 已提交
1187 1188 1189
	machvec=	[IA64] Force the use of a particular machine-vector
			(machvec) in a generic kernel.
			Example: machvec=hpzx1_swiotlb
L
Linus Torvalds 已提交
1190

R
Randy Dunlap 已提交
1191
	max_loop=	[LOOP] Maximum number of loopback devices that can
L
Linus Torvalds 已提交
1192 1193 1194 1195
			be mounted
			Format: <1-256>

	maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
1196 1197 1198 1199
			should make use of.  maxcpus=n : n >= 0 limits the
			kernel to using 'n' processors.  n=0 is a special case,
			it is equivalent to "nosmp", which also disables
			the IO APIC.
L
Linus Torvalds 已提交
1200

1201 1202
	max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater than
			or equal to this physical address is ignored.
B
Bob Picco 已提交
1203

R
Randy Dunlap 已提交
1204
	max_luns=	[SCSI] Maximum number of LUNs to probe.
L
Linus Torvalds 已提交
1205 1206 1207
			Should be between 1 and 2^32-1.

	max_report_luns=
R
Randy Dunlap 已提交
1208
			[SCSI] Maximum number of LUNs received.
L
Linus Torvalds 已提交
1209 1210 1211 1212
			Should be between 1 and 16384.

	mcatest=	[IA-64]

1213
	mce		[X86-32] Machine Check Exception
L
Linus Torvalds 已提交
1214

U
Uwe Hermann 已提交
1215
	mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.txt
1216

L
Linus Torvalds 已提交
1217 1218
	md=		[HW] RAID subsystems devices and level
			See Documentation/md.txt.
R
Randy Dunlap 已提交
1219

L
Linus Torvalds 已提交
1220 1221 1222
	mdacon=		[MDA]
			Format: <first>,<last>
			Specifies range of consoles to be captured by the MDA.
R
Randy Dunlap 已提交
1223

L
Linus Torvalds 已提交
1224 1225 1226
	mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
			Amount of memory to be used when the kernel is not able
			to see the whole system memory or for test.
1227
			[X86-32] Use together with memmap= to avoid physical
L
Linus Torvalds 已提交
1228 1229 1230
			address space collisions. Without memmap= PCI devices
			could be placed at addresses belonging to unused RAM.

1231
	mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
L
Linus Torvalds 已提交
1232 1233
			memory.

1234 1235 1236 1237
	memchunk=nn[KMG]
			[KNL,SH] Allow user to override the default size for
			per-device physically contiguous DMA buffers.

1238
	memmap=exactmap	[KNL,X86-32,X86_64] Enable setting of an exact
L
Linus Torvalds 已提交
1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254
			E820 memory map, as specified by the user.
			Such memmap=exactmap lines can be constructed based on
			BIOS output or other requirements. See the memmap=nn@ss
			option description.

	memmap=nn[KMG]@ss[KMG]
			[KNL] Force usage of a specific region of memory
			Region of memory to be used, from ss to ss+nn.

	memmap=nn[KMG]#ss[KMG]
			[KNL,ACPI] Mark specific memory as ACPI data.
			Region of memory to be used, from ss to ss+nn.

	memmap=nn[KMG]$ss[KMG]
			[KNL,ACPI] Mark specific memory as reserved.
			Region of memory to be used, from ss to ss+nn.
1255 1256 1257 1258
			Example: Exclude memory from 0x18690000-0x1869ffff
			         memmap=64K$0x18690000
			         or
			         memmap=0x10000$0x18690000
L
Linus Torvalds 已提交
1259

1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282
	memory_corruption_check=0/1 [X86]
			Some BIOSes seem to corrupt the first 64k of
			memory when doing things like suspend/resume.
			Setting this option will scan the memory
			looking for corruption.  Enabling this will
			both detect corruption and prevent the kernel
			from using the memory being corrupted.
			However, its intended as a diagnostic tool; if
			repeatable BIOS-originated corruption always
			affects the same memory, you can use memmap=
			to prevent the kernel from using that memory.

	memory_corruption_check_size=size [X86]
			By default it checks for corruption in the low
			64k, making this memory unavailable for normal
			use.  Use this parameter to scan for
			corruption in more or less memory.

	memory_corruption_check_period=seconds [X86]
			By default it checks for corruption every 60
			seconds.  Use this parameter to check at some
			other rate.  0 disables periodic checking.

1283
	memtest=	[KNL,X86] Enable memtest
Y
Yinghai Lu 已提交
1284 1285 1286 1287
			Format: <integer>
			range: 0,4 : pattern number
			default : 0 <disable>

L
Linus Torvalds 已提交
1288 1289 1290
	meye.*=		[HW] Set MotionEye Camera parameters
			See Documentation/video4linux/meye.txt.

1291 1292 1293 1294
	mfgpt_irq=	[IA-32] Specify the IRQ to use for the
			Multi-Function General Purpose Timers on AMD Geode
			platforms.

1295 1296 1297 1298 1299
	mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
			the BIOS has incorrectly applied a workaround. TinyBIOS
			version 0.98 is known to be affected, 0.99 fixes the
			problem by letting the user disable the workaround.

L
Linus Torvalds 已提交
1300 1301
	mga=		[HW,DRM]

1302 1303 1304
	min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this
			physical address is ignored.

1305 1306 1307 1308 1309 1310 1311 1312
	mminit_loglevel=
			[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
			parameter allows control of the logging verbosity for
			the additional memory initialisation checks. A value
			of 0 disables mminit logging and a level of 4 will
			log everything. Information is printed at KERN_DEBUG
			so loglevel=8 may also need to be specified.

L
Linus Torvalds 已提交
1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329
	mousedev.tap_time=
			[MOUSE] Maximum time between finger touching and
			leaving touchpad surface for touch to be considered
			a tap and be reported as a left button click (for
			touchpads working in absolute mode only).
			Format: <msecs>
	mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
			reporting absolute coordinates, such as tablets
	mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
			reporting absolute coordinates, such as tablets

	mpu401=		[HW,OSS]
			Format: <io>,<irq>

	MTD_Partition=	[MTD]
			Format: <name>,<region-number>,<size>,<offset>

R
Randy Dunlap 已提交
1330 1331
	MTD_Region=	[MTD] Format:
			<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
L
Linus Torvalds 已提交
1332 1333

	mtdparts=	[MTD]
1334
			See drivers/mtd/cmdlinepart.c.
L
Linus Torvalds 已提交
1335

1336 1337 1338 1339 1340
	mtdset=		[ARM]
			ARM/S3C2412 JIVE boot control

			See arch/arm/mach-s3c2412/mach-jive.c

L
Linus Torvalds 已提交
1341
	mtouchusb.raw_coordinates=
R
Randy Dunlap 已提交
1342 1343
			[HW] Make the MicroTouch USB driver use raw coordinates
			('y', default) or cooked coordinates ('n')
L
Linus Torvalds 已提交
1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363

	n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card

	NCR_D700=	[HW,SCSI]
			See header of drivers/scsi/NCR_D700.c.

	ncr5380=	[HW,SCSI]

	ncr53c400=	[HW,SCSI]

	ncr53c400a=	[HW,SCSI]

	ncr53c406a=	[HW,SCSI]

	ncr53c8xx=	[HW,SCSI]

	netdev=		[NET] Network devices parameters
			Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
			Note that mem_start is often overloaded to mean
			something different and driver-specific.
R
Randy Dunlap 已提交
1364 1365 1366
			This usage is only documented in each driver source
			file if at all.

1367 1368 1369 1370 1371 1372 1373
	nf_conntrack.acct=
			[NETFILTER] Enable connection tracking flow accounting
			0 to disable accounting
			1 to enable accounting
			Default value depends on CONFIG_NF_CT_ACCT that is
			going to be removed in 2.6.29.

L
Linus Torvalds 已提交
1374
	nfsaddrs=	[NFS]
1375
			See Documentation/filesystems/nfsroot.txt.
L
Linus Torvalds 已提交
1376 1377

	nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
1378
			See Documentation/filesystems/nfsroot.txt.
L
Linus Torvalds 已提交
1379

1380 1381 1382 1383
	nfs.callback_tcpport=
			[NFS] set the TCP port on which the NFSv4 callback
			channel should listen.

1384 1385 1386 1387
	nfs.idmap_cache_timeout=
			[NFS] set the maximum lifetime for idmapper cache
			entries.

1388 1389 1390 1391 1392 1393 1394
	nfs.enable_ino64=
			[NFS] enable 64-bit inode numbers.
			If zero, the NFS client will fake up a 32-bit inode
			number for the readdir() and stat() syscalls instead
			of returning the full 64-bit number.
			The default is to return 64-bit inode numbers.

H
Haavard Skinnemoen 已提交
1395 1396 1397 1398
	nmi_debug=	[KNL,AVR32] Specify one or more actions to take
			when a NMI is triggered.
			Format: [state][,regs][,debounce][,die]

1399
	nmi_watchdog=	[KNL,BUGS=X86-32] Debugging features for SMP kernels
L
Linus Torvalds 已提交
1400

1401
	no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
L
Linus Torvalds 已提交
1402 1403 1404
			emulation library even if a 387 maths coprocessor
			is present.

C
Christoph Lameter 已提交
1405 1406 1407
	noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
			caches in the slab allocator.  Saves per-node memory,
			but will impact performance.
1408

R
Randy Dunlap 已提交
1409 1410
	noalign		[KNL,ARM]

L
Linus Torvalds 已提交
1411 1412 1413 1414 1415 1416 1417
	noapic		[SMP,APIC] Tells the kernel to not make use of any
			IOAPICs that may be present in the system.

	nobats		[PPC] Do not use BATs for mapping kernel lowmem
			on "Classic" PPC cores.

	nocache		[ARM]
R
Randy Dunlap 已提交
1418

1419 1420
	nodelayacct	[KNL] Disable per-task delay accounting

L
Linus Torvalds 已提交
1421 1422
	nodisconnect	[HW,SCSI,M68K] Disables SCSI disconnects.

1423 1424
	nodsp		[SH] Disable hardware DSP at boot time.

1425 1426
	noefi		[X86-32,X86-64] Disable EFI runtime services support.

L
Linus Torvalds 已提交
1427 1428
	noexec		[IA-64]

1429
	noexec		[X86-32,X86-64]
J
Jiri Slaby 已提交
1430
			On X86-32 available only on PAE configured kernels.
L
Linus Torvalds 已提交
1431
			noexec=on: enable non-executable mappings (default)
J
Jiri Slaby 已提交
1432 1433 1434 1435 1436 1437 1438 1439
			noexec=off: disable non-executable mappings

	noexec32	[X86-64]
			This affects only 32-bit executables.
			noexec32=on: enable non-executable mappings (default)
				read doesn't imply executable mappings
			noexec32=off: disable non-executable mappings
				read implies executable mappings
L
Linus Torvalds 已提交
1440

1441 1442
	nofpu		[SH] Disable hardware FPU at boot time.

1443
	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
1444 1445
			register save and restore. The kernel will only save
			legacy floating-point registers on task switch.
L
Linus Torvalds 已提交
1446

A
Andi Kleen 已提交
1447 1448
	noclflush	[BUGS=X86] Don't use the CLFLUSH instruction

1449
	nohlt		[BUGS=ARM,SH]
R
Randy Dunlap 已提交
1450

1451
	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
L
Linus Torvalds 已提交
1452 1453 1454 1455 1456 1457 1458 1459 1460 1461
			instruction doesn't work correctly and not to
			use it.

	nohalt		[IA-64] Tells the kernel not to use the power saving
			function PAL_HALT_LIGHT when idle. This increases
			power-consumption. On the positive side, it reduces
			interrupt wake-up latency, which may improve performance
			in certain environments such as networked servers or
			real-time systems.

1462 1463 1464 1465
	nohz=		[KNL] Boottime enable/disable dynamic ticks
			Valid arguments: on, off
			Default: on

1466
	noirqdebug	[X86-32] Disables the code which attempts to detect and
L
Linus Torvalds 已提交
1467 1468
			disable unhandled interrupt sources.

1469
	no_timer_check	[X86-32,X86_64,APIC] Disables the code which tests for
1470 1471
			broken timer IRQ sources.

L
Linus Torvalds 已提交
1472 1473 1474 1475 1476 1477 1478
	noisapnp	[ISAPNP] Disables ISA PnP code.

	noinitrd	[RAM] Tells the kernel not to load any configured
			initial RAM disk.

	nointroute	[IA-64]

1479 1480
	nojitter	[IA64] Disables jitter checking for ITC timers.

1481
	nolapic		[X86-32,APIC] Do not enable or use the local APIC.
L
Linus Torvalds 已提交
1482

1483
	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
1484

1485 1486
	nox2apic	[X86-64,APIC] Do not enable x2APIC mode.

1487 1488 1489 1490
	x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
			default x2apic cluster mode on platforms
			supporting x2apic.

L
Linus Torvalds 已提交
1491 1492 1493
	noltlbs		[PPC] Do not use large page/tlb entries for kernel
			lowmem mapping on PPC40x.

1494 1495
	nomca		[IA-64] Disable machine check abort handling

1496
	nomce		[X86-32] Machine Check Exception
1497

1498 1499 1500
	nomfgpt		[X86-32] Disable Multi-Function General Purpose
			Timer usage (for AMD Geode machines).

1501
	noreplace-paravirt	[X86-32,PV_OPS] Don't patch paravirt_ops
1502

1503
	noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
1504 1505
			with UP alternatives

L
Linus Torvalds 已提交
1506 1507
	noresidual	[PPC] Don't use residual data on PReP machines.

R
Randy Dunlap 已提交
1508 1509 1510
	noresume	[SWSUSP] Disables resume and restores original swap
			space.

L
Linus Torvalds 已提交
1511 1512 1513 1514 1515 1516
	no-scroll	[VGA] Disables scrollback.
			This is required for the Braillex ib80-piezo Braille
			reader made by F.H. Papenmeier (Germany).

	nosbagart	[IA-64]

1517
	nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1518

1519 1520
	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
			and disable the IO APIC.  legacy for "maxcpus=0".
L
Linus Torvalds 已提交
1521

1522 1523
	nosoftlockup	[KNL] Disable the soft-lockup detector.

L
Linus Torvalds 已提交
1524 1525
	nosync		[HW,M68K] Disables sync negotiation for all devices.

1526
	notsc		[BUGS=X86-32] Disable Time Stamp Counter
L
Linus Torvalds 已提交
1527 1528 1529 1530

	nousb		[USB] Disable the USB subsystem

	nowb		[ARM]
R
Randy Dunlap 已提交
1531

1532 1533 1534 1535
	nptcg=		[IA64] Override max number of concurrent global TLB
			purges which is reported from either PAL_VM_SUMMARY or
			SAL PALO.

1536 1537 1538 1539 1540
	numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
			one of ['zone', 'node', 'default'] can be specified
			This can be set from sysctl after boot.
			See Documentation/sysctl/vm.txt for details.

1541 1542
	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.

1543 1544 1545 1546 1547 1548 1549
	olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
			Rather than timing out after 20 ms if an EC
			command is not properly ACKed, override the length
			of the timeout.  We have interrupts disabled while
			waiting for the ACK, so if this is set too high
			interrupts *may* be lost!

L
Linus Torvalds 已提交
1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567
	opl3=		[HW,OSS]
			Format: <io>

	oprofile.timer=	[HW]
			Use timer interrupt instead of performance counters

	osst=		[HW,SCSI] SCSI Tape Driver
			Format: <buffer_size>,<write_threshold>
			See also Documentation/scsi/st.txt.

	panic=		[KNL] Kernel behaviour on panic
			Format: <timeout>

	parkbd.port=	[HW] Parallel port number the keyboard adapter is
			connected to, default is 0.
			Format: <parport#>
	parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
			0 for XT, 1 for AT (default is AT).
R
Randy Dunlap 已提交
1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589
			Format: <mode>

	parport=	[HW,PPT] Specify parallel ports. 0 disables.
			Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
			Use 'auto' to force the driver to use any
			IRQ/DMA settings detected (the default is to
			ignore detected IRQ/DMA settings because of
			possible conflicts). You can specify the base
			address, IRQ, and DMA settings; IRQ and DMA
			should be numbers, or 'auto' (for using detected
			settings on that particular port), or 'nofifo'
			(to avoid using a FIFO even if it is detected).
			Parallel ports are assigned in the order they
			are specified on the command line, starting
			with parport0.

	parport_init_mode=	[HW,PPT]
			Configure VIA parallel port to operate in
			a specific mode. This is necessary on Pegasos
			computer where firmware has no options for setting
			up parallel port mode and sets it to spp.
			Currently this function knows 686a and 8231 chips.
L
Linus Torvalds 已提交
1590 1591
			Format: [spp|ps2|epp|ecp|ecpepp]

R
Randy Dunlap 已提交
1592 1593 1594
	pas2=		[HW,OSS] Format:
			<io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>

L
Linus Torvalds 已提交
1595 1596 1597
	pas16=		[HW,SCSI]
			See header of drivers/scsi/pas16.c.

1598 1599 1600 1601 1602
	pause_on_oops=
			Halt all CPUs after the first oops has been printed for
			the specified number of seconds.  This is to be used if
			your oopses keep scrolling off the screen.

L
Linus Torvalds 已提交
1603 1604 1605 1606
	pcbit=		[HW,ISDN]

	pcd.		[PARIDE]
			See header of drivers/block/paride/pcd.c.
1607
			See also Documentation/blockdev/paride.txt.
L
Linus Torvalds 已提交
1608

R
Randy Dunlap 已提交
1609
	pci=option[,option...]	[PCI] various PCI subsystem options:
1610
		off		[X86] don't probe for the PCI bus
1611
		bios		[X86-32] force use of PCI BIOS, don't access
R
Randy Dunlap 已提交
1612 1613
				the hardware directly. Use this if your machine
				has a non-standard PCI host bridge.
1614
		nobios		[X86-32] disallow use of PCI BIOS, only direct
R
Randy Dunlap 已提交
1615 1616 1617
				hardware access methods are allowed. Use this
				if you experience crashes upon bootup and you
				suspect they are caused by the BIOS.
1618
		conf1		[X86] Force use of PCI Configuration
R
Randy Dunlap 已提交
1619
				Mechanism 1.
1620
		conf2		[X86] Force use of PCI Configuration
R
Randy Dunlap 已提交
1621
				Mechanism 2.
R
Randy Dunlap 已提交
1622 1623 1624
		noaer		[PCIE] If the PCIEAER kernel config parameter is
				enabled, this kernel boot option can be used to
				disable the use of PCIE advanced error reporting.
1625 1626
		nodomains	[PCI] Disable support for multiple PCI
				root domains (aka PCI segments, in ACPI-speak).
1627
		nommconf	[X86-32,X86_64] Disable use of MMCONFIG for PCI
1628
				Configuration
1629 1630 1631
		nomsi		[MSI] If the PCI_MSI kernel config parameter is
				enabled, this kernel boot option can be used to
				disable the use of MSI interrupts system-wide.
1632
		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
R
Randy Dunlap 已提交
1633 1634 1635 1636 1637 1638 1639
				routing table. These calls are known to be buggy
				on several machines and they hang the machine
				when used, but on other computers it's the only
				way to get the interrupt routing table. Try
				this option if the kernel is unable to allocate
				IRQs or discover secondary PCI buses on your
				motherboard.
1640
		rom		[X86] Assign address space to expansion ROMs.
R
Randy Dunlap 已提交
1641 1642 1643
				Use with caution as certain devices share
				address decoders between ROMs and other
				resources.
1644
		norom		[X86] Do not assign address space to
1645 1646
				expansion ROMs that do not already have
				BIOS assigned address ranges.
1647
		irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
R
Randy Dunlap 已提交
1648 1649 1650
				assigned automatically to PCI devices. You can
				make the kernel exclude IRQs of your ISA cards
				this way.
1651
		pirqaddr=0xAAAAA	[X86] Specify the physical address
R
Randy Dunlap 已提交
1652 1653 1654
				of the PIRQ table (normally generated
				by the BIOS) if it is outside the
				F0000h-100000h range.
1655
		lastbus=N	[X86] Scan all buses thru bus #N. Can be
R
Randy Dunlap 已提交
1656 1657 1658
				useful if the kernel is unable to find your
				secondary buses and you want to tell it
				explicitly which ones they are.
1659
		assign-busses	[X86] Always assign all PCI bus
R
Randy Dunlap 已提交
1660 1661
				numbers ourselves, overriding
				whatever the firmware may have done.
1662
		usepirqmask	[X86] Honor the possible IRQ mask stored
R
Randy Dunlap 已提交
1663 1664 1665 1666 1667
				in the BIOS $PIR table. This is needed on
				some systems with broken BIOSes, notably
				some HP Pavilion N5400 and Omnibook XE3
				notebooks. This will have no effect if ACPI
				IRQ routing is enabled.
1668
		noacpi		[X86] Do not use ACPI for IRQ routing
R
Randy Dunlap 已提交
1669
				or for PCI scanning.
1670
		use_crs		[X86] Use _CRS for PCI resource
1671
				allocation.
R
Randy Dunlap 已提交
1672 1673 1674 1675
		routeirq	Do IRQ routing for all PCI devices.
				This is normally done in pci_enable_device(),
				so this option is a temporary workaround
				for broken drivers that don't call it.
1676 1677
		skip_isa_align	[X86] do not align io start addr, so can
				handle more pci cards
R
Randy Dunlap 已提交
1678 1679 1680 1681 1682
		firmware	[ARM] Do not re-enumerate the bus but instead
				just use the configuration from the
				bootloader. This is currently used on
				IXP2000 systems where the bus has to be
				configured a certain way for adjunct CPUs.
1683 1684 1685 1686 1687
		noearly		[X86] Don't do any early type 1 scanning.
				This might help on some broken boards which
				machine check when some devices' config space
				is read. But various workarounds are disabled
				and some IOMMU drivers will not work.
1688 1689 1690 1691
		bfsort		Sort PCI devices into breadth-first order.
				This sorting is done to get a device
				order compatible with older (<= 2.4) kernels.
		nobfsort	Don't sort PCI devices into breadth-first order.
1692 1693 1694 1695 1696 1697
		cbiosize=nn[KMG]	The fixed amount of bus space which is
				reserved for the CardBus bridge's IO window.
				The default value is 256 bytes.
		cbmemsize=nn[KMG]	The fixed amount of bus space which is
				reserved for the CardBus bridge's memory
				window. The default value is 64 megabytes.
1698

1699 1700 1701 1702 1703 1704
	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
			Management.
		off	Disable ASPM.
		force	Enable ASPM even on devices that claim not to support it.
			WARNING: Forcing ASPM on may cause system lockups.

L
Linus Torvalds 已提交
1705 1706 1707
	pcmv=		[HW,PCMCIA] BadgePAD 4

	pd.		[PARIDE]
1708
			See Documentation/blockdev/paride.txt.
L
Linus Torvalds 已提交
1709 1710 1711 1712 1713 1714 1715

	pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
			boot time.
			Format: { 0 | 1 }
			See arch/parisc/kernel/pdc_chassis.c

	pf.		[PARIDE]
1716
			See Documentation/blockdev/paride.txt.
L
Linus Torvalds 已提交
1717 1718

	pg.		[PARIDE]
1719
			See Documentation/blockdev/paride.txt.
L
Linus Torvalds 已提交
1720 1721

	pirq=		[SMP,APIC] Manual mp-table setup
U
Uwe Hermann 已提交
1722
			See Documentation/x86/i386/IO-APIC.txt.
L
Linus Torvalds 已提交
1723 1724 1725 1726 1727

	plip=		[PPT,NET] Parallel port network link
			Format: { parport<nr> | timid | 0 }
			See also Documentation/parport.txt.

1728 1729 1730 1731
	pmtmr=		[X86] Manual setup of pmtmr I/O Port. 
			Override pmtimer IOPort with a hex value.
			e.g. pmtmr=0x508

1732 1733 1734 1735
	pnp.debug	[PNP]
			Enable PNP debug messages.  This depends on the
			CONFIG_PNP_DEBUG_MESSAGES option.

L
Linus Torvalds 已提交
1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748
	pnpacpi=	[ACPI]
			{ off }

	pnpbios=	[ISAPNP]
			{ on | off | curr | res | no-curr | no-res }

	pnp_reserve_irq=
			[ISAPNP] Exclude IRQs for the autoconfiguration

	pnp_reserve_dma=
			[ISAPNP] Exclude DMAs for the autoconfiguration

	pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
R
Randy Dunlap 已提交
1749
			Ranges are in pairs (I/O port base and size).
L
Linus Torvalds 已提交
1750 1751

	pnp_reserve_mem=
R
Randy Dunlap 已提交
1752 1753
			[ISAPNP] Exclude memory regions for the
			autoconfiguration.
L
Linus Torvalds 已提交
1754 1755
			Ranges are in pairs (memory base and size).

1756 1757 1758 1759 1760
	dynamic_printk
			Enables pr_debug()/dev_dbg() calls if
			CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
			be switched on/off via <debugfs>/dynamic_printk/modules

I
Ingo Molnar 已提交
1761 1762 1763 1764 1765 1766
	print-fatal-signals=
			[KNL] debug: print fatal signals
			print-fatal-signals=1: print segfault info to
			the kernel console.
			default: off.

1767 1768 1769
	printk.time=	Show timing data prefixed to each printk message line
			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)

L
Linus Torvalds 已提交
1770
	profile=	[KNL] Enable kernel profiling via /proc/profile
R
Randy Dunlap 已提交
1771 1772 1773 1774
			Format: [schedule,]<number>
			Param: "schedule" - profile schedule points.
			Param: <number> - step/bucket size as a power of 2 for
				statistical time based profiling.
1775 1776
			Param: "sleep" - profile D-state sleeping (millisecs).
				Requires CONFIG_SCHEDSTATS
1777
			Param: "kvm" - profile VM exits.
L
Linus Torvalds 已提交
1778

R
Randy Dunlap 已提交
1779
	processor.max_cstate=	[HW,ACPI]
L
Linus Torvalds 已提交
1780 1781 1782
			Limit processor to maximum C-state
			max_cstate=9 overrides any DMI blacklist limit.

1783 1784 1785 1786
	processor.nocst	[HW,ACPI]
			Ignore the _CST method to determine C-states,
			instead using the legacy FADT method

L
Linus Torvalds 已提交
1787 1788
	prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk
			before loading.
1789
			See Documentation/blockdev/ramdisk.txt.
L
Linus Torvalds 已提交
1790

R
Randy Dunlap 已提交
1791 1792
	psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
			probe for; one of (bare|imps|exps|lifebook|any).
L
Linus Torvalds 已提交
1793 1794
	psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
			per second.
R
Randy Dunlap 已提交
1795 1796
	psmouse.resetafter=	[HW,MOUSE]
			Try to reset the device after so many bad packets
L
Linus Torvalds 已提交
1797 1798 1799 1800
			(0 = never).
	psmouse.resolution=
			[HW,MOUSE] Set desired mouse resolution, in dpi.
	psmouse.smartscroll=
R
Randy Dunlap 已提交
1801
			[HW,MOUSE] Controls Logitech smartscroll autorepeat.
L
Linus Torvalds 已提交
1802 1803 1804
			0 = disabled, 1 = enabled (default).

	pss=		[HW,OSS] Personal Sound System (ECHO ESC614)
R
Randy Dunlap 已提交
1805 1806
			Format:
			<io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
L
Linus Torvalds 已提交
1807 1808

	pt.		[PARIDE]
1809
			See Documentation/blockdev/paride.txt.
L
Linus Torvalds 已提交
1810

1811 1812 1813 1814
	pty.legacy_count=
			[KNL] Number of legacy pty's. Overwrites compiled-in
			default number.

1815
	quiet		[KNL] Disable most log messages
R
Randy Dunlap 已提交
1816

L
Linus Torvalds 已提交
1817 1818 1819 1820 1821
	r128=		[HW,DRM]

	raid=		[HW,RAID]
			See Documentation/md.txt.

R
Randy Dunlap 已提交
1822
	ramdisk_blocksize=	[RAM]
1823
			See Documentation/blockdev/ramdisk.txt.
R
Randy Dunlap 已提交
1824

L
Linus Torvalds 已提交
1825
	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
1826
			See Documentation/blockdev/ramdisk.txt.
L
Linus Torvalds 已提交
1827

1828 1829 1830
	rcupdate.blimit=	[KNL,BOOT]
			Set maximum number of finished RCU callbacks to process
			in one batch.
D
Dipankar Sarma 已提交
1831

1832 1833
	rcupdate.qhimark=	[KNL,BOOT]
			Set threshold of queued
D
Dipankar Sarma 已提交
1834 1835
			RCU callbacks over which batch limiting is disabled.

1836 1837 1838
	rcupdate.qlowmark=	[KNL,BOOT]
			Set threshold of queued RCU callbacks below which
			batch limiting is re-enabled.
D
Dipankar Sarma 已提交
1839

1840 1841 1842 1843 1844
	rdinit=		[KNL]
			Format: <full_path>
			Run specified binary instead of /init from the ramdisk,
			used for early userspace startup. See initrd.

1845
	reboot=		[BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
L
Linus Torvalds 已提交
1846
			Format: <reboot_mode>[,<reboot_mode2>[,...]]
1847
			See arch/*/kernel/reboot.c or arch/*/kernel/process.c			
L
Linus Torvalds 已提交
1848

1849 1850 1851 1852
	relax_domain_level=
			[KNL, SMP] Set scheduler's default relax_domain_level.
			See Documentation/cpusets.txt.

L
Linus Torvalds 已提交
1853 1854
	reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area

1855
	reservetop=	[X86-32]
1856 1857 1858 1859
			Format: nn[KMG]
			Reserves a hole at the top of the kernel virtual
			address space.

1860 1861 1862
	reset_devices	[KNL] Force drivers to reset the underlying device
			during initialization.

R
Randy Dunlap 已提交
1863 1864
	resume=		[SWSUSP]
			Specify the partition device for software suspend
L
Linus Torvalds 已提交
1865

1866 1867 1868 1869 1870 1871
	resume_offset=	[SWSUSP]
			Specify the offset from the beginning of the partition
			given by "resume=" at which the swap header is located,
			in <PAGE_SIZE> units (needed only for swap files).
			See  Documentation/power/swsusp-and-swap-files.txt

1872 1873
	retain_initrd	[RAM] Keep initrd memory after extraction

L
Linus Torvalds 已提交
1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890
	rhash_entries=	[KNL,NET]
			Set number of hash buckets for route cache

	riscom8=	[HW,SERIAL]
			Format: <io_board1>[,<io_board2>[,...<io_boardN>]]

	ro		[KNL] Mount root device read-only on boot

	root=		[KNL] Root filesystem

	rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
			mount the root filesystem

	rootflags=	[KNL] Set root filesystem mount option string

	rootfstype=	[KNL] Set root filesystem type

1891 1892 1893 1894
	rootwait	[KNL] Wait (indefinitely) for root device to show up.
			Useful for devices that are detected asynchronously
			(e.g. USB and MMC devices).

1895 1896 1897 1898 1899 1900 1901 1902 1903
	root_plug.vendor_id=
			[ROOTPLUG] Override the default vendor ID

	root_plug.product_id=
			[ROOTPLUG] Override the default product ID

	root_plug.debug=
			[ROOTPLUG] Enable debugging output

L
Linus Torvalds 已提交
1904 1905 1906 1907 1908 1909 1910 1911
	rw		[KNL] Mount root device read-write on boot

	S		[KNL] Run init in single mode

	sa1100ir	[NET]
			See drivers/net/irda/sa1100_ir.c.

	sbni=		[NET] Granch SBNI12 leased line adapter
R
Randy Dunlap 已提交
1912

L
Linus Torvalds 已提交
1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926
	sc1200wdt=	[HW,WDT] SC1200 WDT (watchdog) driver
			Format: <io>[,<timeout>[,<isapnp>]]

	scsi_debug_*=	[SCSI]
			See drivers/scsi/scsi_debug.c.

	scsi_default_dev_flags=
			[SCSI] SCSI default device flags
			Format: <integer>

	scsi_dev_flags=	[SCSI] Black/white list entry for vendor and model
			Format: <vendor>:<model>:<flags>
			(flags are integer value)

1927 1928 1929 1930 1931 1932 1933
	scsi_logging_level=	[SCSI] a bit mask of logging levels
			See drivers/scsi/scsi_logging.h for bits.  Also
			settable via sysctl at dev.scsi.logging_level
			(/proc/sys/dev/scsi/logging_level).
			There is also a nice 'scsi_logging_level' script in the
			S390-tools package, available for download at
			http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
L
Linus Torvalds 已提交
1934

1935 1936 1937 1938 1939
	scsi_mod.scan=	[SCSI] sync (default) scans SCSI busses as they are
			discovered.  async scans them in kernel threads,
			allowing boot to proceed.  none ignores them, expecting
			user space to do the scan.

L
Linus Torvalds 已提交
1940 1941 1942 1943 1944 1945 1946 1947 1948
	selinux		[SELINUX] Disable or enable SELinux at boot time.
			Format: { "0" | "1" }
			See security/selinux/Kconfig help text.
			0 -- disable.
			1 -- enable.
			Default value is set via kernel config option.
			If enabled at boot time, /selinux/disable can be used
			later to disable prior to initial policy load.

1949 1950
	selinux_compat_net =
			[SELINUX] Set initial selinux_compat_net flag value.
1951 1952 1953 1954 1955 1956
                        Format: { "0" | "1" }
                        0 -- use new secmark-based packet controls
                        1 -- use legacy packet controls
                        Default value is 0 (preferred).
                        Value can be changed at runtime via
                        /selinux/compat_net.
1957

1958
	serialnumber	[BUGS=X86-32]
L
Linus Torvalds 已提交
1959 1960 1961

	shapers=	[NET]
			Maximal number of shapers.
R
Randy Dunlap 已提交
1962

Y
Yinghai Lu 已提交
1963 1964 1965 1966 1967 1968
	show_msr=	[x86] show boot-time MSR settings
			Format: { <integer> }
			Show boot-time (BIOS-initialized) MSR settings.
			The parameter means the number of CPUs to show,
			for example 1 means boot CPU only.

L
Linus Torvalds 已提交
1969 1970 1971 1972 1973
	sim710=		[SCSI,HW]
			See header of drivers/scsi/sim710.c.

	simeth=		[IA-64]
	simscsi=
R
Randy Dunlap 已提交
1974

L
Linus Torvalds 已提交
1975 1976
	slram=		[HW,MTD]

1977 1978 1979 1980 1981 1982 1983
	slub_debug[=options[,slabs]]	[MM, SLUB]
			Enabling slub_debug allows one to determine the
			culprit if slab objects become corrupted. Enabling
			slub_debug can create guard zones around objects and
			may poison objects when not in use. Also tracks the
			last alloc / free. For more information see
			Documentation/vm/slub.txt.
C
Christoph Lameter 已提交
1984 1985

	slub_max_order= [MM, SLUB]
1986 1987 1988 1989
			Determines the maximum allowed order for slabs.
			A high setting may cause OOMs due to memory
			fragmentation. For more information see
			Documentation/vm/slub.txt.
C
Christoph Lameter 已提交
1990 1991

	slub_min_objects=	[MM, SLUB]
1992 1993 1994 1995 1996 1997
			The minimum number of objects per slab. SLUB will
			increase the slab order up to slub_max_order to
			generate a sufficiently large slab able to contain
			the number of objects indicated. The higher the number
			of objects the smaller the overhead of tracking slabs
			and the less frequently locks need to be acquired.
C
Christoph Lameter 已提交
1998 1999 2000 2001
			For more information see Documentation/vm/slub.txt.

	slub_min_order=	[MM, SLUB]
			Determines the mininum page order for slabs. Must be
2002
			lower than slub_max_order.
C
Christoph Lameter 已提交
2003 2004 2005
			For more information see Documentation/vm/slub.txt.

	slub_nomerge	[MM, SLUB]
2006
			Disable merging of slabs with similar size. May be
C
Christoph Lameter 已提交
2007
			necessary if there is some reason to distinguish
2008 2009
			allocs to different slabs. Debug options disable
			merging on their own.
C
Christoph Lameter 已提交
2010 2011
			For more information see Documentation/vm/slub.txt.

L
Linus Torvalds 已提交
2012 2013 2014
	smart2=		[HW]
			Format: <io1>[,<io2>[,...,<io8>]]

2015
	smp-alt-once	[X86-32,SMP] On a hotplug CPU system, only
2016 2017
			attempt to substitute SMP alternatives once at boot.

B
Bjorn Helgaas 已提交
2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028
	smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
	smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
	smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
	smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
	smsc-ircc2.ircc_irq=	[HW] IRQ line
	smsc-ircc2.ircc_dma=	[HW] DMA channel
	smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
				0: Toshiba Satellite 1800 (GP data pin select)
				1: Fast pin select (default)
				2: ATC IRMode

L
Linus Torvalds 已提交
2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149
	snd-ad1816a=	[HW,ALSA]

	snd-ad1848=	[HW,ALSA]

	snd-ali5451=	[HW,ALSA]

	snd-als100=	[HW,ALSA]

	snd-als4000=	[HW,ALSA]

	snd-azt2320=	[HW,ALSA]

	snd-cmi8330=	[HW,ALSA]

	snd-cmipci=	[HW,ALSA]

	snd-cs4231=	[HW,ALSA]

	snd-cs4232=	[HW,ALSA]

	snd-cs4236=	[HW,ALSA]

	snd-cs4281=	[HW,ALSA]

	snd-cs46xx=	[HW,ALSA]

	snd-dt019x=	[HW,ALSA]

	snd-dummy=	[HW,ALSA]

	snd-emu10k1=	[HW,ALSA]

	snd-ens1370=	[HW,ALSA]

	snd-ens1371=	[HW,ALSA]

	snd-es968=	[HW,ALSA]

	snd-es1688=	[HW,ALSA]

	snd-es18xx=	[HW,ALSA]

	snd-es1938=	[HW,ALSA]

	snd-es1968=	[HW,ALSA]

	snd-fm801=	[HW,ALSA]

	snd-gusclassic=	[HW,ALSA]

	snd-gusextreme=	[HW,ALSA]

	snd-gusmax=	[HW,ALSA]

	snd-hdsp=	[HW,ALSA]

	snd-ice1712=	[HW,ALSA]

	snd-intel8x0=	[HW,ALSA]

	snd-interwave=	[HW,ALSA]

	snd-interwave-stb=
			[HW,ALSA]

	snd-korg1212=	[HW,ALSA]

	snd-maestro3=	[HW,ALSA]

	snd-mpu401=	[HW,ALSA]

	snd-mtpav=	[HW,ALSA]

	snd-nm256=	[HW,ALSA]

	snd-opl3sa2=	[HW,ALSA]

	snd-opti92x-ad1848=
			[HW,ALSA]

	snd-opti92x-cs4231=
			[HW,ALSA]

	snd-opti93x=	[HW,ALSA]

	snd-pmac=	[HW,ALSA]

	snd-rme32=	[HW,ALSA]

	snd-rme96=	[HW,ALSA]

	snd-rme9652=	[HW,ALSA]

	snd-sb8=	[HW,ALSA]

	snd-sb16=	[HW,ALSA]

	snd-sbawe=	[HW,ALSA]

	snd-serial=	[HW,ALSA]

	snd-sgalaxy=	[HW,ALSA]

	snd-sonicvibes=	[HW,ALSA]

	snd-sun-amd7930=
			[HW,ALSA]

	snd-sun-cs4231=	[HW,ALSA]

	snd-trident=	[HW,ALSA]

	snd-usb-audio=	[HW,ALSA,USB]

	snd-via82xx=	[HW,ALSA]

	snd-virmidi=	[HW,ALSA]

	snd-wavefront=	[HW,ALSA]

	snd-ymfpci=	[HW,ALSA]
R
Randy Dunlap 已提交
2150

I
Ingo Molnar 已提交
2151 2152 2153
	softlockup_panic=
			[KNL] Should the soft-lockup detector generate panics.

L
Linus Torvalds 已提交
2154 2155 2156 2157
	sonypi.*=	[HW] Sony Programmable I/O Control Device driver
			See Documentation/sonypi.txt

	specialix=	[HW,SERIAL] Specialix multi-serial port adapter
2158
			See Documentation/serial/specialix.txt.
L
Linus Torvalds 已提交
2159 2160 2161 2162 2163 2164 2165 2166

	spia_io_base=	[HW,MTD]
	spia_fio_base=
	spia_pedr=
	spia_peddr=

	sscape=		[HW,OSS]
			Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
R
Randy Dunlap 已提交
2167

L
Linus Torvalds 已提交
2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183
	st=		[HW,SCSI] SCSI tape parameters (buffers, etc.)
			See Documentation/scsi/st.txt.

	sti=		[PARISC,HW]
			Format: <num>
			Set the STI (builtin display/keyboard on the HP-PARISC
			machines) console (graphic card) which should be used
			as the initial boot-console.
			See also comment in drivers/video/console/sticore.c.

	sti_font=	[HW]
			See comment in drivers/video/console/sticore.c.

	stifb=		[HW]
			Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]

2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199
	sunrpc.pool_mode=
			[NFS]
			Control how the NFS server code allocates CPUs to
			service thread pools.  Depending on how many NICs
			you have and where their interrupts are bound, this
			option will affect which CPUs will do NFS serving.
			Note: this parameter cannot be changed while the
			NFS server is running.

			auto	    the server chooses an appropriate mode
				    automatically using heuristics
			global	    a single global pool contains all CPUs
			percpu	    one pool for each CPU
			pernode	    one pool for each NUMA node (equivalent
				    to global on non-NUMA machines)

L
Linus Torvalds 已提交
2200
	swiotlb=	[IA-64] Number of I/O TLB slabs
R
Randy Dunlap 已提交
2201

L
Linus Torvalds 已提交
2202 2203 2204 2205 2206
	switches=	[HW,M68k]

	sym53c416=	[HW,SCSI]
			See header of drivers/scsi/sym53c416.c.

2207 2208 2209 2210 2211 2212
	sysrq_always_enabled
			[KNL]
			Ignore sysrq setting - this boot parameter will
			neutralize any effect of /proc/sys/kernel/sysrq.
			Useful for debugging.

L
Linus Torvalds 已提交
2213 2214 2215 2216 2217
	t128=		[HW,SCSI]
			See header of drivers/scsi/t128.c.

	tdfx=		[HW,DRM]

D
David Brownell 已提交
2218 2219 2220 2221 2222 2223
	test_suspend=	[SUSPEND]
			Specify "mem" (for Suspend-to-RAM) or "standby" (for
			standby suspend) as the system sleep state to briefly
			enter during system startup.  The system is woken from
			this state using a wakeup-capable RTC alarm.

L
Linus Torvalds 已提交
2224 2225 2226
	thash_entries=	[KNL,NET]
			Set number of hash buckets for TCP connection

2227 2228 2229 2230
	thermal.act=	[HW,ACPI]
			-1: disable all active trip points in all thermal zones
			<degrees C>: override all lowest active trip points

2231 2232
	thermal.crt=	[HW,ACPI]
			-1: disable all critical trip points in all thermal zones
2233
			<degrees C>: override all critical trip points
2234

2235 2236 2237 2238
	thermal.nocrt=	[HW,ACPI]
			Set to disable actions on ACPI thermal zone
			critical and hot trip points.

2239 2240 2241
	thermal.off=	[HW,ACPI]
			1: disable ACPI thermal control

2242 2243 2244 2245
	thermal.psv=	[HW,ACPI]
			-1: disable all passive trip points
			<degrees C>: override all passive trip points to this value

2246 2247 2248 2249 2250
	thermal.tzp=	[HW,ACPI]
			Specify global default ACPI thermal zone polling rate
			<deci-seconds>: poll all this frequency
			0: no polling (default)

L
Linus Torvalds 已提交
2251 2252 2253 2254 2255 2256 2257
	tmscsim=	[HW,SCSI]
			See comment before function dc390_setup() in
			drivers/scsi/tmscsim.c.

	tp720=		[HW,PS2]

	trix=		[HW,OSS] MediaTrix AudioTrix Pro
R
Randy Dunlap 已提交
2258 2259 2260 2261 2262 2263 2264
			Format:
			<io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>

	turbografx.map[2|3]=	[HW,JOY]
			TurboGraFX parallel port interface
			Format:
			<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
L
Linus Torvalds 已提交
2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275
			See also Documentation/input/joystick-parport.txt

	u14-34f=	[HW,SCSI] UltraStor 14F/34F SCSI host adapter
			See header of drivers/scsi/u14-34f.c.

	uart401=	[HW,OSS]
			Format: <io>,<irq>

	uart6850=	[HW,OSS]
			Format: <io>,<irq>

2276 2277 2278 2279 2280 2281 2282 2283
	uhci-hcd.ignore_oc=
			[USB] Ignore overcurrent events (default N).
			Some badly-designed motherboards generate lots of
			bogus events, for ports that aren't wired to
			anything.  Set this parameter to avoid log spamming.
			Note that genuine overcurrent events won't be
			reported either.

2284 2285 2286 2287
	unknown_nmi_panic
			[X86-32,X86-64]
			Set unknown_nmi_panic=1 early on boot.

2288 2289 2290 2291 2292
	usbcore.autosuspend=
			[USB] The autosuspend time delay (in seconds) used
			for newly-detected USB devices (default 2).  This
			is the time required before an idle device will be
			autosuspended.  Devices for which the delay is set
2293
			to a negative value won't be autosuspended at all.
2294

2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313
	usbcore.usbfs_snoop=
			[USB] Set to log all usbfs traffic (default 0 = off).

	usbcore.blinkenlights=
			[USB] Set to cycle leds on hubs (default 0 = off).

	usbcore.old_scheme_first=
			[USB] Start with the old device initialization
			scheme (default 0 = off).

	usbcore.use_both_schemes=
			[USB] Try the other device initialization scheme
			if the first one fails (default 1 = enabled).

	usbcore.initial_descriptor_timeout=
			[USB] Specifies timeout for the initial 64-byte
                        USB_REQ_GET_DESCRIPTOR request in milliseconds
			(default 5000 = 5.0 seconds).

L
Linus Torvalds 已提交
2314 2315
	usbhid.mousepoll=
			[USBHID] The interval which mice are to be polled at.
R
Randy Dunlap 已提交
2316

2317 2318 2319
	add_efi_memmap	[EFI; x86-32,X86-64] Include EFI memory map in
			kernel's map of available physical RAM.

2320
	vdso=		[X86-32,SH,x86-64]
2321
			vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2322 2323 2324
			vdso=1: enable VDSO (default)
			vdso=0: disable VDSO mapping

R
Roland McGrath 已提交
2325 2326 2327 2328 2329
	vdso32=		[X86-32,X86-64]
			vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
			vdso32=1: enable 32-bit VDSO (default)
			vdso32=0: disable 32-bit VDSO mapping

2330 2331 2332
	vector=		[IA-64,SMP]
			vector=percpu: enable percpu vector domain

L
Linus Torvalds 已提交
2333 2334 2335
	video=		[FB] Frame buffer configuration
			See Documentation/fb/modedb.txt.

2336
	vga=		[BOOT,X86-32] Select a particular video mode
U
Uwe Hermann 已提交
2337
			See Documentation/x86/i386/boot.txt and
R
Randy Dunlap 已提交
2338
			Documentation/svga.txt.
L
Linus Torvalds 已提交
2339 2340 2341 2342
			Use vga=ask for menu.
			This is actually a boot loader parameter; the value is
			passed to the kernel using a special protocol.

R
Randy Dunlap 已提交
2343
	vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
L
Linus Torvalds 已提交
2344 2345 2346 2347 2348
			size of <nn>. This can be used to increase the
			minimum size (128MB on x86). It can also be used to
			decrease the size and leave more room for directly
			mapped kernel RAM.

2349 2350
	vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
			Format: <command>
L
Linus Torvalds 已提交
2351

2352 2353 2354 2355 2356
	vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
			Format: <command>

	vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
			Format: <command>
R
Randy Dunlap 已提交
2357

L
Linus Torvalds 已提交
2358 2359
	waveartist=	[HW,OSS]
			Format: <io>,<irq>,<dma>,<dma2>
R
Randy Dunlap 已提交
2360

L
Linus Torvalds 已提交
2361 2362 2363 2364 2365 2366 2367
	wd33c93=	[HW,SCSI]
			See header of drivers/scsi/wd33c93.c.

	wd7000=		[HW,SCSI]
			See header of drivers/scsi/wd7000.c.

	wdt=		[WDT] Watchdog
2368
			See Documentation/watchdog/wdt.txt.
L
Linus Torvalds 已提交
2369 2370 2371 2372 2373

	xd=		[HW,XT] Original XT pre-IDE (RLL encoded) disks.
	xd_geo=		See header of drivers/block/xd.c.

	xirc2ps_cs=	[NET,PCMCIA]
R
Randy Dunlap 已提交
2374 2375
			Format:
			<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
L
Linus Torvalds 已提交
2376

2377 2378 2379
	norandmaps	Don't use address space randomization
			Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space

R
Randy Dunlap 已提交
2380
______________________________________________________________________
L
Linus Torvalds 已提交
2381 2382 2383 2384 2385

TODO:

	Add documentation for ALSA options.
	Add more DRM drivers.