Documentation / kernel-parameters.txt

Based on kernel version 2.6.25. Page generated on 2008-04-18 21:22 EST.

	                          Kernel Parameters
	                          ~~~~~~~~~~~~~~~~~
	
	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
	
	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}".
	
	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:
	
		ACPI	ACPI support is enabled.
		AGP	AGP (Accelerated Graphics Port) is enabled.
		ALSA	ALSA sound support is enabled.
		APIC	APIC support is enabled.
		APM	Advanced Power Management support is enabled.
		AVR32	AVR32 architecture is enabled.
		AX25	Appropriate AX.25 support is enabled.
		BLACKFIN Blackfin architecture is enabled.
		DRM	Direct Rendering Management support is enabled.
		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.
		IP_PNP	IP DHCP, BOOTP, or RARP is enabled.
		ISAPNP	ISA PnP code is enabled.
		ISDN	Appropriate ISDN support is enabled.
		JOY	Appropriate joystick support is enabled.
		LIBATA  Libata driver is enabled
		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.
		MSI	Message Signaled Interrupts (PCI).
		MTD	MTD (Memory Technology Device) support is enabled.
		NET	Appropriate network support is enabled.
		NUMA	NUMA support is enabled.
		GENERIC_TIME The generic timeofday code is enabled.
		NFS	Appropriate NFS support is enabled.
		OSS	OSS sound support is enabled.
		PV_OPS	A paravirtualized kernel is enabled.
		PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.
		PARISC	The PA-RISC architecture is enabled.
		PCI	PCI bus support is enabled.
		PCIE	PCI Express support is enabled.
		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.
		ROOTPLUG The example Root Plug LSM is enabled.
		S390	S390 architecture is enabled.
		SCSI	Appropriate SCSI support is enabled.
				A lot of drivers has their options described inside of
				Documentation/scsi/.
		SECURITY Different security models are enabled.
		SELINUX SELinux support is enabled.
		SERIAL	Serial support is enabled.
		SH	SuperH architecture is enabled.
		SMP	The kernel is an SMP kernel.
		SPARC	Sparc architecture is enabled.
		SWSUSP	Software suspend is enabled.
		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.
		X86-32	X86-32, aka i386 architecture is enabled.
		X86-64	X86-64 architecture is enabled.
				More X86-64 boot options can be found in
				Documentation/x86_64/boot-options.txt .
	
	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
	need or coordination with <Documentation/i386/boot.txt>.
	
	There are also arch-specific kernel-parameters not documented here.
	See for example <Documentation/x86_64/boot-options.txt>.
	
	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.
	
	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.
	
	
		acpi=		[HW,ACPI,X86-64,i386]
				Advanced Configuration and Power Interface
				Format: { force | off | ht | strict | noirq }
				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
				strict -- Be less tolerant of platforms that are not
					strictly ACPI specification compliant.
	
				See also Documentation/power/pm.txt, pci=noacpi
	
		acpi_apic_instance=	[ACPI, IOAPIC]
				Format: <int>
				2: use 2nd APIC table, if available
				1,0: use 1st APIC table
				default: 0
	
		acpi_sleep=	[HW,ACPI] Sleep options
				Format: { s3_bios, s3_mode, s3_beep }
				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.
	
		acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
				Format: { level | edge | high | low }
	
		acpi_irq_balance [HW,ACPI]
				ACPI will balance active IRQs
				default in APIC mode
	
		acpi_irq_nobalance [HW,ACPI]
				ACPI will not move active IRQs (default)
				default in PIC mode
	
		acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
				use by PCI
				Format: <irq>,<irq>...
	
		acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
				Format: <irq>,<irq>...
	
		acpi_no_auto_ssdt	[HW,ACPI] Disable automatic loading of SSDT
	
		acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
				Format: To spoof as Windows 98: ="Microsoft Windows"
	
		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
	
		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.
		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
	
		acpi.debug_layer=	[HW,ACPI]
				Format: <int>
				Each bit of the <int> indicates an ACPI debug layer,
				1: enable, 0: disable. It is useful for boot time
				debugging. After system has booted up, it can be set
				via /sys/module/acpi/parameters/debug_layer.
				CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
				Available bits (add the numbers together) to enable debug output
				for specific parts of the ACPI subsystem:
				0x01 utilities 0x02 hardware 0x04 events 0x08 tables
				0x10 namespace 0x20 parser 0x40 dispatcher
				0x80 executer 0x100 resources 0x200 acpica debugger
				0x400 os services 0x800 acpica disassembler.
				The number can be in decimal or prefixed with 0x in hex.
				Warning: Many of these options can produce a lot of
				output and make your system unusable. Be very careful.
	
		acpi.debug_level=	[HW,ACPI]
				Format: <int>
				Each bit of the <int> indicates an ACPI debug level,
				1: enable, 0: disable. It is useful for boot time
				debugging. After system has booted up, it can be set
				via /sys/module/acpi/parameters/debug_level.
				CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
				Available bits (add the numbers together) to enable different
				debug output levels of the ACPI subsystem:
				0x01 error 0x02 warn 0x04 init 0x08 debug object
				0x10 info 0x20 init names 0x40 parse 0x80 load
				0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
				0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
				0x10000 resources 0x20000 user requests 0x40000 package.
				The number can be in decimal or prefixed with 0x in hex.
				Warning: Many of these options can produce a lot of
				output and make your system unusable. Be very careful.
	
		acpi_pm_good	[X86-32,X86-64]
				Override the pmtimer bug detection: force the kernel
				to assume that this machine's pmtimer latches its value
				and always returns good values.
	
		agp=		[AGP]
				{ off | try_unsupported }
				off: disable AGP support
				try_unsupported: try to drive unsupported chipsets
					(may crash computer or cause data corruption)
	
		enable_timer_pin_1 [i386,x86-64]
				Enable PIN 1 of APIC timer
				Can be useful to work around chipset bugs
				(in particular on some ATI chipsets).
				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.
	
		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.
	
		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.
	
		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>
	
		apc=		[HW,SPARC]
				Power management functions (SPARCstation-4/5 + deriv.)
				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.
	
		apic=		[APIC,i386] Advanced Programmable Interrupt Controller
				Change the output verbosity whilst booting
				Format: { quiet (default) | verbose | debug }
				Change the amount of debugging information output
				when initialising the APIC and IO-APIC components.
	
		apm=		[APM] Advanced Power Management
				See header of arch/i386/kernel/apm.c.
	
		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
	
		atkbd.set=	[HW] Select keyboard code set
				Format: <int> (2 = AT (default), 3 = PS/2)
	
		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))
	
		atkbd.softrepeat= [HW]
				Use software keyboard repeat
	
		autotest	[IA64]
	
		baycom_epp=	[HW,AX25]
				Format: <io>,<mode>
	
		baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
				Format: <io>,<mode>
				See header of drivers/net/hamradio/baycom_par.c.
	
		baycom_ser_fdx=	[HW,AX25]
				BayCom Serial Port AX.25 Modem (Full Duplex Mode)
				Format: <io>,<irq>,<mode>[,<baud>]
				See header of drivers/net/hamradio/baycom_ser_fdx.c.
	
		baycom_ser_hdx=	[HW,AX25]
				BayCom Serial Port AX.25 Modem (Half Duplex Mode)
				Format: <io>,<irq>,<mode>
				See header of drivers/net/hamradio/baycom_ser_hdx.c.
	
		boot_delay=	Milliseconds to delay each printk during boot.
				Values larger than 10 seconds (10000) are changed to
				no delay (0).
				Format: integer
	
		bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
		bttv.radio=	Most important insmod options are available as
				kernel args too.
		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
	
		cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
				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.
	
		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.
	
		ccw_timeout_log [S390]
				See Documentation/s390/CommonIO for details.
	
		cgroup_disable= [KNL] Disable a particular controller
				Format: {name of the controller(s) to disable}
					{Currently supported controllers - "memory"}
	
		checkreqprot	[SELINUX] Set initial checkreqprot flag value.
				Format: { "0" | "1" }
				See security/selinux/Kconfig help text.
				0 -- check protection applied by kernel (includes
					any implied execute protection).
				1 -- check protection requested by application.
				Default value is set via a kernel config option.
				Value can be changed at runtime via
					/selinux/checkreqprot.
	
		cio_ignore=	[S390]
				See Documentation/s390/CommonIO for details.
	
		cio_msg=	[S390]
				See Documentation/s390/CommonIO for details.
	
		clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
				[Deprecated]
				Forces specified clocksource (if available) to be used
				when calculating gettimeofday(). If specified
				clocksource is not available, it defaults to PIT.
				Format: { pit | tsc | cyclone | pmtmr }
	
		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
				[X86-32] pit,hpet,tsc,vmi-timer;
					scx200_hrt on Geode; cyclone on IBM x440
				[MIPS] MIPS
				[PARISC] cr16
				[S390] tod
				[SH] SuperH
				[SPARC64] tick
				[X86-64] hpet,tsc
	
		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.
	
		code_bytes	[IA32/X86_64] How many bytes of object code to print
				in an oops report.
				Range: 0 - 8192
				Default: 64
	
		disable_8254_timer
		enable_8254_timer
				[IA32/X86_64] Disable/Enable interrupt 0 timer routing
				over the 8254 in addition to over the IO-APIC. The
				kernel tries to set a sensible default.
	
		hpet=		[X86-32,HPET] option to control HPET usage
				Format: { enable (default) | disable | force }
				disable: disable HPET and use PIT instead
				force: allow force enabled of undocumented chips (ICH4,
				VIA, nVidia)
	
		com20020=	[HW,NET] ARCnet - COM20020 chipset
				Format:
				<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
	
		com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
				Format: <io>[,<irq>]
	
		com90xx=	[HW,NET]
				ARCnet - COM90xx chipset (memory-mapped buffers)
				Format: <io>[,<irq>[,<memstart>]]
	
		condev=		[HW,S390] console device
		conmode=
	
		console=	[KNL] Output console device and options.
	
			tty<n>	Use the virtual console device <n>.
	
			ttyS<n>[,options]
			ttyUSB0[,options]
				Use the specified serial port.  The options are of
				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.
	
			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,
				switching to the matching ttyS device later.  The
				options are the same as for ttyS, above.
	
		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.
	
		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.
	
		cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
				Format:
				<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
	
		crashkernel=nn[KMG]@ss[KMG]
				[KNL] Reserve a chunk of physical memory to
				hold a kernel to switch to with kexec on panic.
	
		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.
	
		cs4232=		[HW,OSS]
				Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
	
		cs89x0_dma=	[HW,NET]
				Format: <dma>
	
		cs89x0_media=	[HW,NET]
				Format: { rj45 | aui | bnc }
	
		dasd=		[HW,NET]
				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).
	
		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.
	
		decnet.addr=	[HW,NET]
				Format: <area>[,<node>]
				See also Documentation/networking/decnet.txt.
	
		vt.default_blu=	[VT]
				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.
	
		vt.default_grn=	[VT]
				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.
	
		vt.default_red=	[VT]
				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.
	
		vt.default_utf8=
				[VT]
				Format=<0|1>
				Set system-wide default UTF-8 mode for all tty's.
				Default is 1, i.e. UTF-8 mode is enabled for all
				newly opened terminals.
	
		dhash_entries=	[KNL]
				Set number of hash buckets for dentry cache.
	
		digi=		[HW,SERIAL]
				IO parameters + enable/disable command.
	
		digiepca=	[HW,SERIAL]
				See drivers/char/README.epca and
				Documentation/digiepca.txt.
	
		disable_mtrr_trim [X86, Intel and AMD only]
				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.
	
		dmasound=	[HW,OSS] Sound subsystem buffers
	
		dscc4.setup=	[NET]
	
		dtc3181e=	[HW,SCSI]
	
		earlyprintk=	[X86-32,X86-64,SH,BLACKFIN]
				earlyprintk=vga
				earlyprintk=serial[,ttySn[,baudrate]]
	
				Append ",keep" to not disable it when the real console
				takes over.
	
				Only vga or serial at a time, not both.
	
				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]
				Format: {"of[f]" | "sk[ipmbr]"}
				See comment in arch/i386/boot/edd.S
	
		eisa_irq_edge=	[PARISC,HW]
				See header of drivers/parisc/eisa.c.
	
		elanfreq=	[X86-32]
				See comment before function elanfreq_setup() in
				arch/i386/kernel/cpu/cpufreq/elanfreq.c.
	
		elevator=	[IOSCHED]
				Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
				See Documentation/block/as-iosched.txt and
				Documentation/block/deadline-iosched.txt for details.
	
		elfcorehdr=	[X86-32, X86_64]
				Specifies physical address of start of kernel core
				image elf header. Generally kexec loader will
				pass this option to capture kernel.
				See Documentation/kdump/kdump.txt for details.
	
		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.
	
		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>]
	
		failslab=
		fail_page_alloc=
		fail_make_request=[KNL]
				General fault injection mechanism.
				Format: <interval>,<probability>,<space>,<times>
				See also /Documentation/fault-injection/.
	
		fd_mcs=		[HW,SCSI]
				See header of drivers/scsi/fd_mcs.c.
	
		fdomain=	[HW,SCSI]
				See header of drivers/scsi/fdomain.c.
	
		floppy=		[HW]
				See Documentation/floppy.txt.
	
		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]
	
		gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
				Format: off | on
				default: on
	
		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.
				Format: 0 | 1 (for off | on)
	
		hcl=		[IA-64] SGI's Hardware Graph compatibility layer
	
		hd=		[EIDE] (E)IDE hard drive subsystem geometry
				Format: <cyl>,<head>,<sect>
	
		hd?=		[HW] (E)IDE subsystem
		hd?lun=		See Documentation/ide/ide.txt.
	
		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.
	
		highres=	[KNL] Enable/disable high resolution timer mode.
				Valid parameters: "on", "off"
				Default: "on"
	
		hisax=		[HW,ISDN]
				See Documentation/isdn/README.HiSax.
	
		hugepages=	[HW,X86-32,IA-64] Maximal number of HugeTLB pages.
		hugepagesz=	[HW,IA-64,PPC] The size of the HugeTLB pages.
	
		i8042.direct	[HW] Put keyboard port into non-translated mode
		i8042.dumbkbd	[HW] Pretend that controller can only read data from
				     keyboard and cannot control its state
				     (Don't attempt to blink the leds)
		i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
		i8042.nokbd	[HW] Don't check/create keyboard port
		i8042.noloop	[HW] Disable the AUX Loopback command while probing
				     for the AUX port
		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]
	
		i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
				indicates that the driver is running on unsupported
				hardware.
		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
				Format: ide=nodma or ide=doubler or ide=reverse
				See Documentation/ide/ide.txt.
	
		ide?=		[HW] (E)IDE subsystem
				Format: ide?=noprobe or chipset specific parameters.
				See Documentation/ide/ide.txt.
	
		idebus=		[HW] (E)IDE subsystem - VLB/PCI bus speed
				See Documentation/ide/ide.txt.
	
		idle=		[X86]
				Format: idle=poll or idle=mwait
				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.
	
		ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
				Claim all unknown PCI IDE storage controllers.
	
		ignore_loglevel	[KNL]
				Ignore loglevel setting - this will print /all/
				kernel messages to the console. Useful for debugging.
	
		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]
	
		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.
			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.
	
		io_delay=	[X86-32,X86-64] I/O delay method
			0x80
				Standard port 0x80 based delay
			0xed
				Alternate port 0xed based delay (needed on some systems)
			udelay
				Simple two microseconds delay
			none
				No delay
	
		io7=		[HW] IO7 for Marvel based alpha systems
				See comment before marvel_specify_io7 in
				arch/alpha/kernel/core_marvel.c.
	
		ip=		[IP_PNP]
				See Documentation/filesystems/nfsroot.txt.
	
		ip2=		[HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
				See comment before ip2_setup() in
				drivers/char/ip2/ip2base.c.
	
		ips=		[HW,SCSI] Adaptec / IBM ServeRAID controller
				See header of drivers/scsi/ips.c.
	
		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>....
	
		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.
	
		isapnp=		[ISAPNP]
				Format: <RDP>,<reset>,<pci_scan>,<verbosity>
	
		isolcpus=	[KNL,SMP] Isolate CPUs from the general scheduler.
				Format:
				<cpu number>,...,<cpu number>
				or
				<cpu number>-<cpu number>  (must be a positive range in ascending order)
				or a mixture
				<cpu number>,...,<cpu number>-<cpu number>
				This option can be used to specify one or more CPUs
				to isolate from the general SMP balancing and scheduling
				algorithms. The only way to move a process onto or off
				an "isolated" CPU is via the CPU affinity syscalls.
				<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
				alternative -- manually setting the CPU mask of all
				tasks in the system -- can cause problems and
				suboptimal load balancer performance.
	
		iucv=		[HW,NET]
	
		js=		[HW,JOY] Analog joystick
				See Documentation/input/joystick.txt.
	
		kernelcore=nn[KMG]	[KNL,X86-32,IA-64,PPC,X86-64] This parameter
				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.
	
		movablecore=nn[KMG]	[KNL,X86-32,IA-64,PPC,X86-64] This parameter
				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.
	
		keepinitrd	[HW,ARM]
	
		kstack=N	[X86-32,X86-64] Print N words from the kernel stack
				in oops dumps.
	
		l2cr=		[PPC]
	
		lapic		[X86-32,APIC] Enable the local APIC even if BIOS
				disabled it.
	
		lapic_timer_c2_ok	[X86-32,x86-64,APIC] trust the local apic timer in
				C2 power state.
	
		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.
	
		libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
				when set.
				Format: <int>
	
		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.
	
				If there are multiple matching configurations changing
				the same attribute, the last one is used.
	
		load_ramdisk=	[RAM] List of ramdisks to load from floppy
				See Documentation/ramdisk.txt.
	
		lockd.nlm_grace_period=P  [NFS] Assign grace period.
				Format: <integer>
	
		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>
	
		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.
				Format: { n | nk | nM }
				n must be a power of two.  The default size
				is set in the kernel config file.
	
		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.
	
		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>
	
		mac5380=	[HW,SCSI] Format:
				<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
	
		mac53c9x=	[HW,SCSI] Format:
				<num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
	
		machvec=	[IA64] Force the use of a particular machine-vector
				(machvec) in a generic kernel.
				Example: machvec=hpzx1_swiotlb
	
		max_loop=	[LOOP] Maximum number of loopback devices that can
				be mounted
				Format: <1-256>
	
		maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
				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.
	
		max_addr=[KMG]	[KNL,BOOT,ia64] All physical memory greater than or
				equal to this physical address is ignored.
	
		max_luns=	[SCSI] Maximum number of LUNs to probe.
				Should be between 1 and 2^32-1.
	
		max_report_luns=
				[SCSI] Maximum number of LUNs received.
				Should be between 1 and 16384.
	
		mcatest=	[IA-64]
	
		mce		[X86-32] Machine Check Exception
	
		mce=option	[X86-64] See Documentation/x86_64/boot-options.txt
	
		md=		[HW] RAID subsystems devices and level
				See Documentation/md.txt.
	
		mdacon=		[MDA]
				Format: <first>,<last>
				Specifies range of consoles to be captured by the MDA.
	
		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.
				[X86-32] Use together with memmap= to avoid physical
				address space collisions. Without memmap= PCI devices
				could be placed at addresses belonging to unused RAM.
	
		mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
				memory.
	
		memmap=exactmap	[KNL,X86-32,X86_64] Enable setting of an exact
				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.
				Example: Exclude memory from 0x18690000-0x1869ffff
				         memmap=64K$0x18690000
				         or
				         memmap=0x10000$0x18690000
	
		meye.*=		[HW] Set MotionEye Camera parameters
				See Documentation/video4linux/meye.txt.
	
		mfgpt_irq=	[IA-32] Specify the IRQ to use for the
				Multi-Function General Purpose Timers on AMD Geode
				platforms.
	
		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.
	
		mga=		[HW,DRM]
	
		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>
	
		MTD_Region=	[MTD] Format:
				<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
	
		mtdparts=	[MTD]
				See drivers/mtd/cmdlinepart.c.
	
		mtouchusb.raw_coordinates=
				[HW] Make the MicroTouch USB driver use raw coordinates
				('y', default) or cooked coordinates ('n')
	
		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.
				This usage is only documented in each driver source
				file if at all.
	
		nfsaddrs=	[NFS]
				See Documentation/filesystems/nfsroot.txt.
	
		nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
				See Documentation/filesystems/nfsroot.txt.
	
		nfs.callback_tcpport=
				[NFS] set the TCP port on which the NFSv4 callback
				channel should listen.
	
		nfs.idmap_cache_timeout=
				[NFS] set the maximum lifetime for idmapper cache
				entries.
	
		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.
	
		nmi_debug=	[KNL,AVR32] Specify one or more actions to take
				when a NMI is triggered.
				Format: [state][,regs][,debounce][,die]
	
		nmi_watchdog=	[KNL,BUGS=X86-32] Debugging features for SMP kernels
	
		no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
				emulation library even if a 387 maths coprocessor
				is present.
	
		noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
				caches in the slab allocator.  Saves per-node memory,
				but will impact performance.
	
		noalign		[KNL,ARM]
	
		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]
	
		nodelayacct	[KNL] Disable per-task delay accounting
	
		nodisconnect	[HW,SCSI,M68K] Disables SCSI disconnects.
	
		noefi		[X86-32,X86-64] Disable EFI runtime services support.
	
		noexec		[IA-64]
	
		noexec		[X86-32,X86-64]
				noexec=on: enable non-executable mappings (default)
				noexec=off: disable nn-executable mappings
	
		nofxsr		[BUGS=X86-32] Disables x86 floating point extended
				register save and restore. The kernel will only save
				legacy floating-point registers on task switch.
	
		noclflush	[BUGS=X86] Don't use the CLFLUSH instruction
	
		nohlt		[BUGS=ARM]
	
		no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
				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.
	
		nohz=		[KNL] Boottime enable/disable dynamic ticks
				Valid arguments: on, off
				Default: on
	
		noirqbalance	[X86-32,SMP,KNL] Disable kernel irq balancing
	
		noirqdebug	[X86-32] Disables the code which attempts to detect and
				disable unhandled interrupt sources.
	
		no_timer_check	[X86-32,X86_64,APIC] Disables the code which tests for
				broken timer IRQ sources.
	
		noisapnp	[ISAPNP] Disables ISA PnP code.
	
		noinitrd	[RAM] Tells the kernel not to load any configured
				initial RAM disk.
	
		nointroute	[IA-64]
	
		nojitter	[IA64] Disables jitter checking for ITC timers.
	
		nolapic		[X86-32,APIC] Do not enable or use the local APIC.
	
		nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
	
		noltlbs		[PPC] Do not use large page/tlb entries for kernel
				lowmem mapping on PPC40x.
	
		nomca		[IA-64] Disable machine check abort handling
	
		nomce		[X86-32] Machine Check Exception
	
		nomfgpt		[X86-32] Disable Multi-Function General Purpose
				Timer usage (for AMD Geode machines).
	
		noreplace-paravirt	[X86-32,PV_OPS] Don't patch paravirt_ops
	
		noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
				with UP alternatives
	
		noresidual	[PPC] Don't use residual data on PReP machines.
	
		noresume	[SWSUSP] Disables resume and restores original swap
				space.
	
		no-scroll	[VGA] Disables scrollback.
				This is required for the Braillex ib80-piezo Braille
				reader made by F.H. Papenmeier (Germany).
	
		nosbagart	[IA-64]
	
		nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
	
		nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
				and disable the IO APIC.  legacy for "maxcpus=0".
	
		nosoftlockup	[KNL] Disable the soft-lockup detector.
	
		nosync		[HW,M68K] Disables sync negotiation for all devices.
	
		notsc		[BUGS=X86-32] Disable Time Stamp Counter
	
		nousb		[USB] Disable the USB subsystem
	
		nowb		[ARM]
	
		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.
	
		nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
	
		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).
				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.