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

  Hyphens (dashes) and underscores are equivalent in parameter names, so
  	log_buf_len=1M print-fatal-signals=1
  can also be entered as
  	log-buf-len=1M print_fatal_signals=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.

  	ARM	ARM architecture 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.
  	DYNAMIC_DEBUG Build in debug messages and enable them at runtime

  	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.

  	FTRACE	Function tracing enabled.

  	GCOV	GCOV profiling is enabled.

  	HW	Appropriate hardware is enabled.

  	IA-64	IA-64 architecture is enabled.

  	IMA     Integrity measurement architecture is enabled.

  	IOSCHED	More than one I/O scheduler is enabled.

  	IP_PNP	IP DHCP, BOOTP, or RARP is enabled.

  	IPV6	IPv6 support is enabled.

  	ISAPNP	ISA PnP code is enabled.
  	ISDN	Appropriate ISDN support is enabled.
  	JOY	Appropriate joystick support is enabled.

  	KGDB	Kernel debugger support is enabled.

  	KVM	Kernel Virtual Machine 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.

  	MIPS	MIPS architecture 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.
  	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.
  	S390	S390 architecture is enabled.
  	SCSI	Appropriate SCSI support is enabled.

  			A lot of drivers have their options described inside
  			the Documentation/scsi/ sub-directory.

  	SECURITY Different security models are enabled.

  	SELINUX SELinux support is enabled.

  	APPARMOR AppArmor 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 (hibernation) is enabled.
  	SUSPEND	System suspend states are enabled.

  	TPM	TPM drivers are enabled.

  	TS	Appropriate touchscreen support is enabled.

  	UMS	USB Mass Storage 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/x86_64/boot-options.txt .

  	X86	Either 32-bit or 64-bit x86 (same as X86-32+X86-64)

  	XEN	Xen support is enabled

  
  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/x86/boot.txt>.

  There are also arch-specific kernel-parameters not documented here.

  See for example <Documentation/x86/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.

  Finally, the [KMG] suffix is commonly described after a number of kernel
  parameter values. These 'K', 'M', and 'G' letters represent the _binary_
  multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
  bytes respectively. Such letter suffixes can also be entirely omitted.

  	acpi=		[HW,ACPI,X86]

  			Advanced Configuration and Power Interface

  			Format: { force | off | strict | noirq | rsdt }

  			force -- enable ACPI if default was off
  			off -- disable ACPI if default was on
  			noirq -- do not use ACPI for IRQ routing

  			strict -- Be less tolerant of platforms that are not

  				strictly ACPI specification compliant.

  			rsdt -- prefer RSDT over (default) XSDT

  			copy_dsdt -- copy DSDT to memory

  			See also Documentation/power/pm.txt, pci=noacpi

  	acpi_rsdp=	[ACPI,EFI,KEXEC]
  			Pass the RSDP address to the kernel, mostly used
  			on machines running EFI runtime service to boot the
  			second kernel for kdump.

  	acpi_apic_instance=	[ACPI, IOAPIC]
  			Format: <int>
  			2: use 2nd APIC table, if available
  			1,0: use 1st APIC table

  			default: 0

  	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.debug_layer=	[HW,ACPI,ACPI_DEBUG]
  	acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]

  			Format: <int>

  			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, ...

  			The debug_level mask defaults to "info".  See
  			Documentation/acpi/debug.txt for more information about
  			debug layers and levels.

  			Enable processor driver info messages:
  			    acpi.debug_layer=0x20000000
  			Enable PCI/PCI interrupt routing info messages:
  			    acpi.debug_layer=0x400000

  			Enable AML "Debug" output, i.e., stores to the Debug
  			object while interpreting AML:
  			    acpi.debug_layer=0xffffffff acpi.debug_level=0x2

  			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.

  	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_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  			Format: <irq>,<irq>...
  
  	acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
  			use by PCI
  			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_pm_good	[X86]

  			Override the pmtimer bug detection: force the kernel
  			to assume that this machine's pmtimer latches its value
  			and always returns good values.

  	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
  			Format: { level | edge | high | low }
  
  	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_sleep=	[HW,ACPI] Sleep options
  			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,

  				  old_ordering, nonvs, sci_force_enable }

  			See Documentation/power/video.txt for information on
  			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.
  			s4_nohwsig prevents ACPI hardware signature from being
  			used during resume from hibernation.
  			old_ordering causes the ACPI 1.0 ordering of the _PTS
  			control method, with respect to putting devices into
  			low power states, to be enforced (the ACPI 2.0 ordering
  			of _PTS is used by default).

  			nonvs prevents the kernel from saving/restoring the
  			ACPI NVS memory during suspend/hibernation and resume.

  			sci_force_enable causes the kernel to set SCI_EN directly
  			on resume from S1/S3 (which is against the ACPI spec,
  			but some broken systems don't work without it).

  
  	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_enforce_resources=	[ACPI]
  			{ strict | lax | no }
  			Check for resource conflicts between native drivers
  			and ACPI OperationRegions (SystemIO and SystemMemory
  			only). IO ports and memory declared in ACPI might be
  			used by the ACPI subsystem in arbitrary AML code and
  			can interfere with legacy drivers.
  			strict (default): access to resources claimed by ACPI
  			is denied; legacy drivers trying to access reserved
  			resources will fail to bind to device using them.
  			lax: access to resources claimed by ACPI is allowed;
  			legacy drivers trying to access reserved resources
  			will bind successfully but a warning message is logged.
  			no: ACPI OperationRegions are not marked as reserved,
  			no further checks are performed.

  	add_efi_memmap	[EFI; X86] Include EFI memory map in
  			kernel's map of available physical RAM.

  	agp=		[AGP]
  			{ off | try_unsupported }
  			off: disable AGP support
  			try_unsupported: try to drive unsupported chipsets
  				(may crash computer or cause data corruption)

  	ALSA		[HW,ALSA]
  			See Documentation/sound/alsa/alsa-parameters.txt

  	alignment=	[KNL,ARM]
  			Allow the default userspace alignment fault handler
  			behaviour to be specified.  Bit 0 enables warnings,
  			bit 1 enables fixups, and bit 2 sends a segfault.

  	amd_iommu=	[HW,X86-84]
  			Pass parameters to the AMD IOMMU driver in the system.
  			Possible values are:

  			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

  			off	  - do not initialize any AMD IOMMU found in
  				    the system

  	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,X86-32] 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.

  	autoconf=	[IPV6]
  			See Documentation/networking/ipv6.txt.

  	show_lapic=	[APIC,X86] Advanced Programmable Interrupt Controller
  			Limit apic dumping. The parameter defines the maximal
  			number of local apics being dumped. Also it is possible
  			to set it to "all" by meaning -- no limit here.
  			Format: { 1 (default) | 2 | ... | all }.
  			The parameter valid if only apic=debug or
  			apic=verbose is specified.
  			Example: apic=debug show_lapic=all

  	apm=		[APM] Advanced Power Management

  			See header of arch/x86/kernel/apm_32.c.

  	arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  			Format: <io>,<irq>,<nodeID>
  
  	ataflop=	[HW,M68k]
  
  	atarimouse=	[HW,MOUSE] Atari Mouse

  	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	[IA-64]

  	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

  	bootmem_debug	[KNL] Enable bootmem allocator debug messages.

  	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

  	bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
  			firmware feature for flushing multiple hpte entries
  			at a time.

  	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.

  	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=	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;

  				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

  			arch/x86/include/asm/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.

  	cmo_free_hint=	[PPC] Format: { yes | no }
  			Specify whether pages are marked as being inactive
  			when they are freed.  This is used in CMO environments
  			to determine OS memory pressure for page stealing by
  			a hypervisor.
  			Default: yes

  	code_bytes	[X86] How many bytes of object code to print

  			in an oops report.

  			Range: 0 - 8192
  			Default: 64

  	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.

                  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.

  	consoleblank=	[KNL] The console blank (screen saver) timeout in
  			seconds. Defaults to 10*60 = 10mins. A value of 0
  			disables the blank timer.

  	coredump_filter=
  			[KNL] Change the default value for
  			/proc/<pid>/coredump_filter.
  			See also Documentation/filesystems/proc.txt.

  	cpuidle.off=1	[CPU_IDLE]
  			disable the cpuidle sub-system

  	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver

  			Format:
  			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

  	crashkernel=size[KMG][@offset[KMG]]
  			[KNL] Using kexec, Linux can switch to a 'crash kernel'
  			upon panic. This parameter reserves the physical
  			memory region [offset, offset + size] for that kernel
  			image. If '@offset' is omitted, then a suitable offset
  			is selected automatically. Check
  			Documentation/kdump/kdump.txt for further details.

  	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 an example.

  	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

  	ddebug_query=   [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
  			time. See Documentation/dynamic-debug-howto.txt for
  			details.

  	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.

  	debug_objects	[KNL] Enable object debugging

  	no_debug_objects
  			[KNL] Disable object debugging

  	debugpat	[X86] Enable PAT debugging

  	decnet.addr=	[HW,NET]

  			Format: <area>[,<node>]
  			See also Documentation/networking/decnet.txt.

  	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.

  	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/serial/digiepca.txt.

  	disable=	[IPV6]
  			See Documentation/networking/ipv6.txt.

  	disable_ddw     [PPC/PSERIES]
  			Disable Dynamic DMA Window support. Use this if
  			to workaround buggy firmware.

  	disable_ipv6=	[IPV6]
  			See Documentation/networking/ipv6.txt.

  	disable_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 disables that.

  	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.

  	disable_timer_pin_1 [X86]

  			Disable PIN 1 of APIC timer
  			Can be useful to work around chipset bugs.

  	dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
  			this option disables the debugging code at boot.
  
  	dma_debug_entries=<number>
  			This option allows to tune the number of preallocated
  			entries for DMA-API debugging code. One entry is
  			required per DMA-API allocation. Use this if the
  			DMA-API debugging code disables itself because the
  			architectural default is too low.

  	dma_debug_driver=<driver_name>
  			With this option the DMA-API debugging driver
  			filter feature can be enabled at boot time. Just
  			pass the driver to filter for as the parameter.
  			The filter can be disabled or changed to another
  			driver later using sysfs.

  	dscc4.setup=	[NET]

  	earlycon=	[KNL] Output early console device and options.
  		uart[8250],io,<addr>[,options]
  		uart[8250],mmio,<addr>[,options]

  		uart[8250],mmio32,<addr>[,options]

  			Start an early, polled-mode console on the 8250/16550
  			UART at the specified I/O port or MMIO address.

  			MMIO inter-register address stride is either 8-bit
  			(mmio) or 32-bit (mmio32).

  			The options are the same as for ttyS, above.

  	earlyprintk=	[X86,SH,BLACKFIN]

  			earlyprintk=vga
  			earlyprintk=serial[,ttySn[,baudrate]]

  			earlyprintk=ttySn[,baudrate]

  			earlyprintk=dbgp[debugController#]

  			Append ",keep" to not disable it when the real console

  			takes over.

  			Only vga or serial or usb debug port at a time.

  
  			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.

  	ekgdboc=	[X86,KGDB] Allow early kernel console debugging
  			ekgdboc=kbd

  			This is designed to be used in conjunction with

  			the boot argument: earlyprintk=vga

  	edd=		[EDD]

  			Format: {"off" | "on" | "skip[mbr]"}

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

  	elanfreq=	[X86-32]

  			See comment before function elanfreq_setup() in

  			arch/x86/kernel/cpu/cpufreq/elanfreq.c.

  
  	elevator=	[IOSCHED]

  			Format: {"cfq" | "deadline" | "noop"}

  			See Documentation/block/as-iosched.txt and
  			Documentation/block/deadline-iosched.txt for details.

  	elfcorehdr=	[IA-64,PPC,SH,X86]

  			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.

  	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 that.

  	enable_timer_pin_1 [X86]

  			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.

  	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.

  	erst_disable	[ACPI]
  			Disable Error Record Serialization Table (ERST)
  			support.

  	ether=		[HW,NET] Ethernet cards parameters
  			This option is obsoleted by the "netdev=" option, which
  			has equivalent usage. See its documentation for details.

  	failslab=
  	fail_page_alloc=
  	fail_make_request=[KNL]
  			General fault injection mechanism.
  			Format: <interval>,<probability>,<space>,<times>
  			See also /Documentation/fault-injection/.

  	floppy=		[HW]

  			See Documentation/blockdev/floppy.txt.

  	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.

  	ftrace=[tracer]

  			[FTRACE] will set and start the specified tracer

  			as early as possible in order to facilitate early
  			boot debugging.

  	ftrace_dump_on_oops[=orig_cpu]

  			[FTRACE] will dump the trace buffers on oops.

  			If no parameter is passed, ftrace will dump
  			buffers of all CPUs, but if you pass orig_cpu, it will
  			dump only the buffer of the CPU that triggered the
  			oops.

  
  	ftrace_filter=[function-list]
  			[FTRACE] Limit the functions traced by the function
  			tracer at boot up. function-list is a comma separated
  			list of functions. This list can be changed at run
  			time by the set_ftrace_filter file in the debugfs

  			tracing directory.

  
  	ftrace_notrace=[function-list]
  			[FTRACE] Do not trace the functions specified in
  			function-list. This list can be changed at run time
  			by the set_ftrace_notrace file in the debugfs
  			tracing directory.

  	ftrace_graph_filter=[function-list]
  			[FTRACE] Limit the top level callers functions traced
  			by the function graph tracer at boot up.
  			function-list is a comma separated list of functions
  			that can be changed at run time by the
  			set_graph_function file in the debugfs tracing directory.

  	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

  	gcov_persist=	[GCOV] When non-zero (default), profiling data for
  			kernel modules is saved and remains accessible via
  			debugfs, even when the module is unloaded/reloaded.
  			When zero, profiling data is discarded and associated
  			debugfs files are removed at module unload time.

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

  	hashdist=	[KNL,NUMA] Large hashes allocated during boot
  			are distributed across NUMA nodes.  Defaults on

  			for 64-bit NUMA, 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>

  	hest_disable	[ACPI]
  			Disable Hardware Error Source Table (HEST) support;
  			corresponding firmware-first mode error processing
  			logic will be disabled.

  	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.

  	hlt		[BUGS=ARM,SH]
  
  	hpet=		[X86-32,HPET] option to control HPET usage
  			Format: { enable (default) | disable | force |
  				verbose }
  			disable: disable HPET and use PIT instead
  			force: allow force enabled of undocumented chips (ICH4,
  				VIA, nVidia)
  			verbose: show contents of HPET registers during setup

  	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.

  			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)

  			Note that 1GB pages can only be allocated at boot time
  			using hugepages= and not freed afterwards.

  	hvc_iucv=	[S390] Number of z/VM IUCV hypervisor console (HVC)
  			       terminal devices. Valid values: 0..8

  	hvc_iucv_allow=	[S390] Comma-separated list of z/VM user IDs.
  			       If specified, z/VM IUCV HVC accepts connections
  			       from listed z/VM user IDs only.

  	keep_bootcon	[KNL]
  			Do not unregister boot console at start. This is only
  			useful for debugging when something happens in the window
  			between unregistering the boot console and initializing
  			the real console.

  	i2c_bus=	[HW] Override the default board specific I2C bus speed

  			     or register an additional I2C bus that is not
  			     registered from board initialization code.

  			     Format:
  			     <bus_id>,<clkrate>

  	i8042.debug	[HW] Toggle i8042 debug mode

  	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.notimeout	[HW] Ignore timeout condition signalled by conroller

  	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.

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

  	ide-core.nodma=	[HW] (E)IDE subsystem
  			Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc

  			.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
  			.cdrom .chs .ignore_cable are additional options

  			See Documentation/ide/ide.txt.

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

  	idle=		[X86]

  			Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
  			Poll forces a polling idle loop that can slightly
  			improve 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.
  			idle=halt: Halt is forced to be used for CPU idle.

  			In such case C2/C3 won't be used again.

  			idle=nomwait: Disable mwait for CPU C-states

  	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.

  	ima_audit=	[IMA]
  			Format: { "0" | "1" }
  			0 -- integrity auditing messages. (Default)
  			1 -- enable informational integrity auditing messages.
  
  	ima_hash=	[IMA]

  			Format: { "sha1" | "md5" }

  			default: "sha1"

  	ima_tcb		[IMA]
  			Load a policy which meets the needs of the Trusted
  			Computing Base.  This means IMA will measure all
  			programs exec'd, files mmap'd for exec, and all files
  			opened for read by uid=0.

  	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>

  	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option

  		on
  			Enable intel iommu driver.

  		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.

  		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.

  		sp_off [Default Off]
  			By default, super page will be supported if Intel IOMMU
  			has the capability. With this option, super page will
  			not be supported.

  	intremap=	[X86-64, Intel-IOMMU]
  			Format: { on (default) | off | nosid }
  			on	enable Interrupt Remapping (default)
  			off	disable Interrupt Remapping
  			nosid	disable Source ID checking

  	inttest=	[IA-64]

  
  	iomem=		Disable strict checking of access to MMIO memory
  		strict	regions from userspace.
  		relaxed
  
  	iommu=		[x86]
  		off
  		force
  		noforce
  		biomerge
  		panic
  		nopanic
  		merge
  		nomerge
  		forcesac
  		soft

  		pt	[x86, IA-64]

  
  	io7=		[HW] IO7 for Marvel based alpha systems
  			See comment before marvel_specify_io7 in
  			arch/alpha/kernel/core_marvel.c.

  	io_delay=	[X86] 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

  	ip=		[IP_PNP]

  			See Documentation/filesystems/nfs/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.

  	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. You can move a process onto or off an
  			"isolated" CPU via the CPU affinity syscalls or cpuset.

  			<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.

  	keepinitrd	[HW,ARM]

  	kernelcore=nn[KMG]	[KNL,X86,IA-64,PPC] 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.

  	kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
  			Format: <Controller#>[,poll interval]
  			The controller # is the number of the ehci usb debug
  			port as it is probed via PCI.  The poll interval is
  			optional and is the number seconds in between
  			each poll cycle to the debug port in case you need
  			the functionality for interrupting the kernel with
  			gdb or control-c on the dbgp connection.  When
  			not using this parameter you use sysrq-g to break into
  			the kernel debugger.

  	kgdboc=		[KGDB,HW] kgdb over consoles.

  			Requires a tty driver that supports console polling,
  			or a supported polling keyboard driver (non-usb).

  			 Serial only format: <serial_device>[,baud]
  			 keyboard only format: kbd
  			 keyboard and serial format: kbd,<serial_device>[,baud]
  			Optional Kernel mode setting:
  			 kms, kbd format: kms,kbd
  			 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]

  	kgdbwait	[KGDB] Stop kernel execution and enter the
  			kernel debugger at the earliest opportunity.

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

  	kmemleak=	[KNL] Boot-time kmemleak enable/disable
  			Valid arguments: on, off
  			Default: on

  	kstack=N	[X86] Print N words from the kernel stack

  			in oops dumps.

  	kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
  			Default is 0 (don't ignore, but inject #GP)
  
  	kvm.oos_shadow=	[KVM] Disable out-of-sync shadow paging.
  			Default is 1 (enabled)

  	kvm.mmu_audit=	[KVM] This is a R/W parameter which allows audit
  			KVM MMU at runtime.

  			Default is 0 (off)

  	kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.

  			Default is 1 (enabled)

  
  	kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)
  			for all guests.

  			Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.

  	kvm-intel.ept=	[KVM,Intel] Disable extended page tables
  			(virtualized MMU) support on capable Intel chips.
  			Default is 1 (enabled)
  
  	kvm-intel.emulate_invalid_guest_state=
  			[KVM,Intel] Enable emulation of invalid guest states
  			Default is 0 (disabled)
  
  	kvm-intel.flexpriority=
  			[KVM,Intel] Disable FlexPriority feature (TPR shadow).
  			Default is 1 (enabled)
  
  	kvm-intel.unrestricted_guest=
  			[KVM,Intel] Disable unrestricted guest feature
  			(virtualized real and unpaged mode) on capable
  			Intel chips. Default is 1 (enabled)
  
  	kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification
  			feature (tagged TLBs) on capable Intel chips.
  			Default is 1 (enabled)

  	l2cr=		[PPC]

  	l3cr=		[PPC]

  	lapic		[X86-32,APIC] Enable the local APIC even if BIOS

  			disabled it.

  	lapic_timer_c2_ok	[X86,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.ignore_hpa=	[LIBATA] Ignore HPA limit
  			libata.ignore_hpa=0	  keep BIOS limits (default)
  			libata.ignore_hpa=1	  ignore limits, using full disk

  	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.

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

  			* dump_id: dump IDENTIFY data.

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

  	memblock=debug	[KNL] Enable memblock debug messages.

  	load_ramdisk=	[RAM] List of ramdisks to load from floppy

  			See Documentation/blockdev/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[KMG]	Sets the size of the printk ring buffer,
  			in bytes.  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>

  	machvec=	[IA-64] Force the use of a particular machine-vector

  			(machvec) in a generic kernel.
  			Example: machvec=hpzx1_swiotlb

  	machtype=	[Loongson] Share the same kernel image file between different
  			 yeeloong laptop.
  			Example: machtype=lemote-yeeloong-2f-7inch

  	max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater
  			than or equal to this physical address is ignored.

  
  	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_loop=	[LOOP] The number of loop block devices that get
  	(loop.max_loop)	unconditionally pre-created at init time. The default
  			number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
  			of statically allocating a predefined number, loop
  			devices can be requested on-demand with the
  			/dev/loop-control interface.

  	mcatest=	[IA-64]

  	mce		[X86-32] Machine Check Exception

  	mce=option	[X86-64] See Documentation/x86/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.

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

  	memmap=exactmap	[KNL,X86] 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

  	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.

  	memtest=	[KNL,X86] Enable memtest

  			Format: <integer>

  			default : 0 <disable>

  			Specifies the number of memtest passes to be
  			performed. Each pass selects another test
  			pattern from a given set of patterns. Memtest
  			fills the memory with this pattern, validates
  			memory contents and reserves bad memory
  			regions that are detected.

  	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]

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

  	mini2440=	[ARM,HW,KNL]
  			Format:[0..2][b][c][t]
  			Default: "0tb"
  			MINI2440 configuration specification:
  			0 - The attached screen is the 3.5" TFT
  			1 - The attached screen is the 7" TFT
  			2 - The VGA Shield is attached (1024x768)
  			Leaving out the screen size parameter will not load
  			the TFT driver, and the framebuffer will be left
  			unconfigured.
  			b - Enable backlight. The TFT backlight pin will be
  			linked to the kernel VESA blanking code and a GPIO
  			LED. This parameter is not necessary when using the
  			VGA shield.
  			c - Enable the s3c camera interface.
  			t - Reserved for enabling touchscreen support. The
  			touchscreen support is not enabled in the mainstream
  			kernel as of 2.6.30, a preliminary port can be found
  			in the "bleeding edge" mini2440 support kernel at
  			http://repo.or.cz/w/linux-2.6/mini2440.git

  	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.

  	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

  	movablecore=nn[KMG]	[KNL,X86,IA-64,PPC] 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.

  	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.

  	multitce=off	[PPC]  This parameter disables the use of the pSeries
  			firmware feature for updating multiple TCE entries
  			at a time.

  	onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
  
  			Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
  
  			boundary - index of last SLC block on Flex-OneNAND.
  				   The remaining blocks are configured as MLC blocks.
  			lock	 - Configure if Flex-OneNAND boundary should be locked.
  				   Once locked, the boundary cannot be changed.
  				   1 indicates lock status, 0 indicates unlock status.

  	mtdset=		[ARM]
  			ARM/S3C2412 JIVE boot control
  
  			See arch/arm/mach-s3c2412/mach-jive.c

  	mtouchusb.raw_coordinates=

  			[HW] Make the MicroTouch USB driver use raw coordinates
  			('y', default) or cooked coordinates ('n')

  	mtrr_chunk_size=nn[KMG] [X86]

  			used for mtrr cleanup. It is largest continuous chunk

  			that could hold holes aka. UC entries.
  
  	mtrr_gran_size=nn[KMG] [X86]
  			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.

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

  	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.

  	nf_conntrack.acct=
  			[NETFILTER] Enable connection tracking flow accounting
  			0 to disable accounting
  			1 to enable accounting

  			Default value is 0.

  	nfsaddrs=	[NFS] Deprecated.  Use ip= instead.

  			See Documentation/filesystems/nfs/nfsroot.txt.

  
  	nfsroot=	[NFS] nfs root filesystem for disk-less boxes.

  			See Documentation/filesystems/nfs/nfsroot.txt.

  	nfsrootdebug	[NFS] enable nfsroot debugging messages.
  			See Documentation/filesystems/nfs/nfsroot.txt.

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

  	nfs.cache_getent=
  			[NFS] sets the pathname to the program which is used
  			to update the NFS client cache entries.
  
  	nfs.cache_getent_timeout=
  			[NFS] sets the timeout after which an attempt to
  			update a cache entry is deemed to have failed.

  	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.

  	nfs.nfs4_disable_idmapping=
  			[NFSv4] When set, this option disables the NFSv4
  			idmapper on the client, but only if the mount
  			is using the 'sec=sys' security flavour. This may
  			make migration from legacy NFSv2/v3 systems easier
  			provided that the server has the appropriate support.
  			The default is to always enable NFSv4 idmapping.

  	nmi_debug=	[KNL,AVR32,SH] Specify one or more actions to take

  			when a NMI is triggered.
  			Format: [state][,regs][,debounce][,die]

  	nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels

  			Format: [panic,][nopanic,][num]

  			Valid num: 0

  			0 - turn nmi_watchdog off

  			When panic is specified, panic when an NMI watchdog

  			timeout occurs (or 'nopanic' to override the opposite
  			default).

  			This is useful when you use a panic=... timeout and
  			need the box quickly up again.

  	netpoll.carrier_timeout=
  			[NET] Specifies amount of time (in seconds) that
  			netpoll should wait for a carrier. By default netpoll
  			waits 4 seconds.

  	no387		[BUGS=X86-32] Tells the kernel to use the 387 maths

  			emulation library even if a 387 maths coprocessor
  			is present.

  	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.

  	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.

  	noautogroup	Disable scheduler automatic task group creation.

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

  	noclflush	[BUGS=X86] Don't use the CLFLUSH instruction

  	nodelayacct	[KNL] Disable per-task delay accounting

  	nodisconnect	[HW,SCSI,M68K] Disables SCSI disconnects.

  	nodsp		[SH] Disable hardware DSP at boot time.

  	noefi		[X86] Disable EFI runtime services support.

  	noexec		[IA-64]

  	noexec		[X86]

  			On X86-32 available only on PAE configured kernels.

  			noexec=on: enable non-executable mappings (default)

  			noexec=off: disable non-executable mappings

  	nosmep		[X86]
  			Disable SMEP (Supervisor Mode Execution Protection)
  			even if it is supported by processor.

  	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

  	nofpu		[SH] Disable hardware FPU at boot time.

  	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.

  	noxsave		[BUGS=X86] Disables x86 extended register state save
  			and restore using xsave. The kernel will fallback to
  			enabling legacy floating-point and sse state.

  	nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
  			wfi(ARM) instruction doesn't work correctly and not to
  			use it. This is also useful when using JTAG debugger.

  	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt

  			instruction doesn't work correctly and not to
  			use it.

  	no_file_caps	Tells the kernel not to honor file capabilities.  The
  			only way then for a file to be executed with privilege
  			is to be setuid root or executed by root.

  	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

  	noiotrap	[SH] Disables trapped I/O port accesses.

  	noirqdebug	[X86-32] Disables the code which attempts to detect and

  			disable unhandled interrupt sources.

  	no_timer_check	[X86,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.

  	nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt
  			remapping.

  			[Deprecated - use intremap=off]

  	nointroute	[IA-64]

  	nojitter	[IA-64] Disables jitter checking for ITC timers.

  	no-kvmclock	[X86,KVM] Disable paravirtualized KVM clock driver

  	no-kvmapf	[X86,KVM] Disable paravirtualized asynchronous page
  			fault handling.

  	no-steal-acc    [X86,KVM] Disable paravirtualized steal time accounting.
  			steal time is computed, but won't influence scheduler
  			behaviour

  	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).

  	nopat		[X86] Disable PAT (page attribute table extension of
  			pagetables) support.

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

  	noreplace-paravirt	[X86,IA-64,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

  	nowatchdog	[KNL] Disable the lockup detector (NMI watchdog).

  	nowb		[ARM]

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

  	nptcg=		[IA-64] Override max number of concurrent global TLB

  			purges which is reported from either PAL_VM_SUMMARY or
  			SAL PALO.

  	nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
  			could support.  nr_cpus=n : n >= 1 limits the kernel to
  			supporting 'n' processors. Later in runtime you can not
  			use hotplug cpu feature to put more cpu back to online.
  			just like you compile the kernel NR_CPUS=n

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

  	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.

  	ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
  			See Documentation/debugging-via-ohci1394.txt for more
  			info.

  	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!

  	omap_mux=	[OMAP] Override bootloader pin multiplexing.
  			Format: <mux_mode0.mode_name=value>...
  			For example, to override I2C bus2:
  			omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100

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

  	oprofile.cpu_type=	Force an oprofile cpu type
  			This might be useful if you have an older oprofile
  			userland or if you want common events.

  			Format: { arch_perfmon }
  			arch_perfmon: [X86] Force use of architectural

  				perfmon on Intel CPUs instead of the
  				CPU specific event set.

  	oops=panic	Always panic on oopses. Default is to just kill the
  			process, but there is a small probability of
  			deadlocking the machine.

  			This will also cause panics on machine check exceptions.
  			Useful together with panic=30 to trigger a reboot.

  	OSS		[HW,OSS]
  			See Documentation/sound/oss/oss-parameters.txt

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

  			timeout > 0: seconds before rebooting
  			timeout = 0: wait forever
  			timeout < 0: reboot immediately

  			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.
  			Currently this function knows 686a and 8231 chips.

  			Format: [spp|ps2|epp|ecp|ecpepp]

  	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.

  	pcbit=		[HW,ISDN]
  
  	pcd.		[PARIDE]
  			See header of drivers/block/paride/pcd.c.

  			See also Documentation/blockdev/paride.txt.

  	pci=option[,option...]	[PCI] various PCI subsystem options:

  		earlydump	[X86] dump PCI config space before the kernel
  			        changes anything

  		off		[X86] don't probe for the PCI bus

  		bios		[X86-32] force use of PCI BIOS, don't access

  				the hardware directly. Use this if your machine
  				has a non-standard PCI host bridge.

  		nobios		[X86-32] disallow use of PCI BIOS, only direct

  				hardware access methods are allowed. Use this
  				if you experience crashes upon bootup and you
  				suspect they are caused by the BIOS.

  		conf1		[X86] Force use of PCI Configuration

  				Mechanism 1.

  		conf2		[X86] Force use of PCI Configuration

  				Mechanism 2.

  		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.

  		nodomains	[PCI] Disable support for multiple PCI
  				root domains (aka PCI segments, in ACPI-speak).

  		nommconf	[X86] Disable use of MMCONFIG for PCI

  				Configuration

  		check_enable_amd_mmconf [X86] check for and enable
  				properly configured MMIO access to PCI
  				config space on AMD family 10h CPU

  		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.

  		noioapicquirk	[APIC] Disable all boot interrupt quirks.
  				Safety option to keep boot IRQs enabled. This
  				should never be necessary.

  		ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
  				primary IO-APIC for bridges that cannot disable
  				boot IRQs. This fixes a source of spurious IRQs
  				when the system masks IRQs.

  		noioapicreroute	[APIC] Disable workaround that uses the
  				boot IRQ equivalent of an IRQ that connects to
  				a chipset where boot IRQs cannot be disabled.
  				The opposite of ioapicreroute.

  		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt

  				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.

  		rom		[X86] Assign address space to expansion ROMs.

  				Use with caution as certain devices share
  				address decoders between ROMs and other
  				resources.

  		norom		[X86] Do not assign address space to

  				expansion ROMs that do not already have
  				BIOS assigned address ranges.

  		nobar		[X86] Do not assign address space to the
  				BARs that weren't assigned by the BIOS.

  		irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be

  				assigned automatically to PCI devices. You can
  				make the kernel exclude IRQs of your ISA cards
  				this way.

  		pirqaddr=0xAAAAA	[X86] Specify the physical address

  				of the PIRQ table (normally generated
  				by the BIOS) if it is outside the
  				F0000h-100000h range.

  		lastbus=N	[X86] Scan all buses thru bus #N. Can be

  				useful if the kernel is unable to find your
  				secondary buses and you want to tell it
  				explicitly which ones they are.

  		assign-busses	[X86] Always assign all PCI bus

  				numbers ourselves, overriding
  				whatever the firmware may have done.

  		usepirqmask	[X86] Honor the possible IRQ mask stored

  				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.

  		noacpi		[X86] Do not use ACPI for IRQ routing

  				or for PCI scanning.

  		use_crs		[X86] Use PCI host bridge window information
  				from ACPI.  On BIOSes from 2008 or later, this
  				is enabled by default.  If you need to use this,
  				please report a bug.
  		nocrs		[X86] Ignore PCI host bridge windows from ACPI.
  			        If you need to use this, please report a bug.

  		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.