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                          Kernel Parameters
                          ~~~~~~~~~~~~~~~~~
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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

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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}".

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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:
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	ACPI	ACPI support is enabled.
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	AGP	AGP (Accelerated Graphics Port) is enabled.
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	ALSA	ALSA sound support is enabled.
	APIC	APIC support is enabled.
	APM	Advanced Power Management support is enabled.
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	AVR32	AVR32 architecture is enabled.
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	AX25	Appropriate AX.25 support is enabled.
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	BLACKFIN Blackfin architecture is enabled.
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	DRM	Direct Rendering Management support is enabled.
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	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.
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	IP_PNP	IP DHCP, BOOTP, or RARP is enabled.
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	ISAPNP	ISA PnP code is enabled.
	ISDN	Appropriate ISDN support is enabled.
	JOY	Appropriate joystick support is enabled.
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	LIBATA  Libata driver is enabled
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	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.
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	MSI	Message Signaled Interrupts (PCI).
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	MTD	MTD (Memory Technology Device) support is enabled.
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	NET	Appropriate network support is enabled.
	NUMA	NUMA support is enabled.
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	GENERIC_TIME The generic timeofday code is enabled.
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	NFS	Appropriate NFS support is enabled.
	OSS	OSS sound support is enabled.
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	PV_OPS	A paravirtualized kernel is enabled.
	PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.
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	PARISC	The PA-RISC architecture is enabled.
	PCI	PCI bus support is enabled.
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	PCIE	PCI Express support is enabled.
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	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.
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	ROOTPLUG The example Root Plug LSM is enabled.
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	S390	S390 architecture is enabled.
	SCSI	Appropriate SCSI support is enabled.
			A lot of drivers has their options described inside of
			Documentation/scsi/.
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	SECURITY Different security models are enabled.
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	SELINUX SELinux support is enabled.
	SERIAL	Serial support is enabled.
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	SH	SuperH architecture is enabled.
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	SMP	The kernel is an SMP kernel.
	SPARC	Sparc architecture is enabled.
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	SWSUSP	Software suspend (hibernation) is enabled.
	SUSPEND	System suspend states are enabled.
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	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.
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	X86-32	X86-32, aka i386 architecture is enabled.
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	X86-64	X86-64 architecture is enabled.
			More X86-64 boot options can be found in
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			Documentation/x86/x86_64/boot-options.txt .
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	X86	Either 32bit or 64bit x86 (same as X86-32+X86-64)
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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
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need or coordination with <Documentation/x86/i386/boot.txt>.
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There are also arch-specific kernel-parameters not documented here.
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See for example <Documentation/x86/x86_64/boot-options.txt>.
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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.

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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.


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	acpi=		[HW,ACPI,X86-64,i386]
			Advanced Configuration and Power Interface
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			Format: { force | off | ht | strict | noirq }
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			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
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			strict -- Be less tolerant of platforms that are not
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				strictly ACPI specification compliant.

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			See also Documentation/power/pm.txt, pci=noacpi
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	acpi_apic_instance=	[ACPI, IOAPIC]
			Format: <int>
			2: use 2nd APIC table, if available
			1,0: use 1st APIC table
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			default: 0
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	acpi_sleep=	[HW,ACPI] Sleep options
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			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
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			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.
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			s4_nohwsig prevents ACPI hardware signature from being
			used during resume from hibernation.
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			old_ordering causes the ACPI 1.0 ordering of the _PTS
			control method, wrt putting devices into low power
			states, to be enforced (the ACPI 2.0 ordering of _PTS is
			used by default).
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	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
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			Format: { level | edge | high | low }
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	acpi_irq_balance [HW,ACPI]
			ACPI will balance active IRQs
			default in APIC mode
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	acpi_irq_nobalance [HW,ACPI]
			ACPI will not move active IRQs (default)
			default in PIC mode
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	acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
			use by PCI
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			Format: <irq>,<irq>...

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	acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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			Format: <irq>,<irq>...

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	acpi_no_auto_ssdt	[HW,ACPI] Disable automatic loading of SSDT

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

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	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
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	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.
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	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
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	acpi.debug_layer=	[HW,ACPI]
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			Format: <int>
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			Each bit of the <int> indicates an ACPI debug layer,
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			1: enable, 0: disable. It is useful for boot time
			debugging. After system has booted up, it can be set
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			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]
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			Format: <int>
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			Each bit of the <int> indicates an ACPI debug level,
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			which corresponds to the level in an ACPI_DEBUG_PRINT
			statement.  After system has booted up, this mask
			can be set via /sys/module/acpi/parameters/debug_level.

			CONFIG_ACPI_DEBUG must be enabled for this to produce
			any output.  The number can be in decimal or prefixed
			with 0x in hex.  Some of these options produce so much
			output that the system is unusable.

			The following global components are defined by the
			ACPI CA:
			       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.
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 	acpi.power_nocheck=	[HW,ACPI]
 			Format: 1/0 enable/disable the check of power state.
 			On some bogus BIOS the _PSC object/_STA object of
 			power resource can't return the correct device power
 			state. In such case it is unneccessary to check its
 			power state again in power transition.
 			1 : disable the power state check

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

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

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	enable_timer_pin_1 [i386,x86-64]
			Enable PIN 1 of APIC timer
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			Can be useful to work around chipset bugs
			(in particular on some ATI chipsets).
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			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.

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	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.
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	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.

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	amd_iommu=	[HW,X86-84]
			Pass parameters to the AMD IOMMU driver in the system.
			Possible values are:
			isolate - enable device isolation (each device, as far
			          as possible, will get its own protection
			          domain)
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			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

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

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	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>

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	apc=		[HW,SPARC]
			Power management functions (SPARCstation-4/5 + deriv.)
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			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.

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	apic=		[APIC,i386] Advanced Programmable Interrupt Controller
			Change the output verbosity whilst booting
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			Format: { quiet (default) | verbose | debug }
			Change the amount of debugging information output
			when initialising the APIC and IO-APIC components.
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	apm=		[APM] Advanced Power Management
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			See header of arch/x86/kernel/apm_32.c.
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	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

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	atkbd.set=	[HW] Select keyboard code set
			Format: <int> (2 = AT (default), 3 = PS/2)
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	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))
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	atkbd.softrepeat= [HW]
			Use software keyboard repeat
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	autotest	[IA64]

	baycom_epp=	[HW,AX25]
			Format: <io>,<mode>
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	baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
			Format: <io>,<mode>
			See header of drivers/net/hamradio/baycom_par.c.

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	baycom_ser_fdx=	[HW,AX25]
			BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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			Format: <io>,<irq>,<mode>[,<baud>]
			See header of drivers/net/hamradio/baycom_ser_fdx.c.

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	baycom_ser_hdx=	[HW,AX25]
			BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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			Format: <io>,<irq>,<mode>
			See header of drivers/net/hamradio/baycom_ser_hdx.c.

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	boot_delay=	Milliseconds to delay each printk during boot.
			Values larger than 10 seconds (10000) are changed to
			no delay (0).
			Format: integer

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	bootmem_debug	[KNL] Enable bootmem allocator debug messages.

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	bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
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	bttv.radio=	Most important insmod options are available as
			kernel args too.
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	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

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	cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
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			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.

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

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	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.

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	ccw_timeout_log [S390]
			See Documentation/s390/CommonIO for details.
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	cgroup_disable= [KNL] Disable a particular controller
			Format: {name of the controller(s) to disable}
				{Currently supported controllers - "memory"}

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	checkreqprot	[SELINUX] Set initial checkreqprot flag value.
			Format: { "0" | "1" }
			See security/selinux/Kconfig help text.
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			0 -- check protection applied by kernel (includes
				any implied execute protection).
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			1 -- check protection requested by application.
			Default value is set via a kernel config option.
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			Value can be changed at runtime via
				/selinux/checkreqprot.

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

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	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
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			[Deprecated]
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			Forces specified clocksource (if available) to be used
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			when calculating gettimeofday(). If specified
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			clocksource is not available, it defaults to PIT.
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			Format: { pit | tsc | cyclone | pmtmr }

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	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
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			[X86-32] pit,hpet,tsc,vmi-timer;
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				scx200_hrt on Geode; cyclone on IBM x440
			[MIPS] MIPS
			[PARISC] cr16
			[S390] tod
			[SH] SuperH
			[SPARC64] tick
			[X86-64] hpet,tsc

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	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.

494 495
	code_bytes	[IA32/X86_64] How many bytes of object code to print
			in an oops report.
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			Range: 0 - 8192
			Default: 64

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	hpet=		[X86-32,HPET] option to control HPET usage
			Format: { enable (default) | disable | force }
			disable: disable HPET and use PIT instead
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			force: allow force enabled of undocumented chips (ICH4,
			VIA, nVidia)
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	com20020=	[HW,NET] ARCnet - COM20020 chipset
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			Format:
			<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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	com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
			Format: <io>[,<irq>]

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	com90xx=	[HW,NET]
			ARCnet - COM90xx chipset (memory-mapped buffers)
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			Format: <io>[,<irq>[,<memstart>]]

	condev=		[HW,S390] console device
	conmode=
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	console=	[KNL] Output console device and options.

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

		ttyS<n>[,options]
524
		ttyUSB0[,options]
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			Use the specified serial port.  The options are of
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			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.
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		uart[8250],io,<addr>[,options]
		uart[8250],mmio,<addr>[,options]
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			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.

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                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.

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	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.

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	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.

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	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
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			Format:
			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
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	crashkernel=nn[KMG]@ss[KMG]
			[KNL] Reserve a chunk of physical memory to
			hold a kernel to switch to with kexec on panic.

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	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.

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	cs4232=		[HW,OSS]
			Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>

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

	cs89x0_media=	[HW,NET]
			Format: { rj45 | aui | bnc }
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	dasd=		[HW,NET]
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			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).

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	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.

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	debug_objects	[KNL] Enable object debugging

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	debugpat	[X86] Enable PAT debugging

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

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	vt.default_blu=	[VT]
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			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.

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	vt.default_grn=	[VT]
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			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.

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	vt.default_red=	[VT]
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			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.

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	vt.default_utf8=
			[VT]
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			Format=<0|1>
			Set system-wide default UTF-8 mode for all tty's.
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			Default is 1, i.e. UTF-8 mode is enabled for all
			newly opened terminals.
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	dhash_entries=	[KNL]
			Set number of hash buckets for dentry cache.
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	digi=		[HW,SERIAL]
			IO parameters + enable/disable command.

	digiepca=	[HW,SERIAL]
			See drivers/char/README.epca and
			Documentation/digiepca.txt.

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	disable_mtrr_cleanup [X86]
	enable_mtrr_cleanup [X86]
			The kernel tries to adjust MTRR layout from continuous
			to discrete, to make X server driver able to add WB
			entry later. This parameter enables/disables that.

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

	mtrr_gran_size=nn[KMG] [X86]
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			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.
673

674
	disable_mtrr_trim [X86, Intel and AMD only]
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			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.

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	dmasound=	[HW,OSS] Sound subsystem buffers

	dscc4.setup=	[NET]

	dtc3181e=	[HW,SCSI]

686
	earlyprintk=	[X86-32,X86-64,SH,BLACKFIN]
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			earlyprintk=vga
			earlyprintk=serial[,ttySn[,baudrate]]
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			earlyprintk=dbgp
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			Append ",keep" to not disable it when the real console
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			takes over.

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			Only vga or serial or usb debug port at a time.
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			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]
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			Format: {"off" | "on" | "skip[mbr]"}
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	eisa_irq_edge=	[PARISC,HW]
			See header of drivers/parisc/eisa.c.

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	elanfreq=	[X86-32]
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			See comment before function elanfreq_setup() in
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			arch/x86/kernel/cpu/cpufreq/elanfreq.c.
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	elevator=	[IOSCHED]
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			Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
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			See Documentation/block/as-iosched.txt and
			Documentation/block/deadline-iosched.txt for details.

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	elfcorehdr=	[IA64,PPC,SH,X86-32,X86_64]
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			Specifies physical address of start of kernel core
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			image elf header. Generally kexec loader will
			pass this option to capture kernel.
			See Documentation/kdump/kdump.txt for details.
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	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.
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	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>]

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

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	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.

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	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.

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	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]

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	gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
			Format: off | on
			default: on

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	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.
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			Format: 0 | 1 (for off | on)
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	hcl=		[IA-64] SGI's Hardware Graph compatibility layer

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

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

803 804 805 806
	highres=	[KNL] Enable/disable high resolution timer mode.
			Valid parameters: "on", "off"
			Default: "on"

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	hisax=		[HW,ISDN]
			See Documentation/isdn/README.HiSax.

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	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.
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			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)
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			Note that 1GB pages can only be allocated at boot time
			using hugepages= and not freed afterwards.
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	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.
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	hlt		[BUGS=ARM,SH]

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	i8042.debug	[HW] Toggle i8042 debug mode
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	i8042.direct	[HW] Put keyboard port into non-translated mode
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	i8042.dumbkbd	[HW] Pretend that controller can only read data from
			     keyboard and cannot control its state
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			     (Don't attempt to blink the leds)
	i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
835
	i8042.nokbd	[HW] Don't check/create keyboard port
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	i8042.noloop	[HW] Disable the AUX Loopback command while probing
			     for the AUX port
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	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]

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	i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
			indicates that the driver is running on unsupported
			hardware.
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	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
868
			Format: ide=nodma or ide=doubler
869
			See Documentation/ide/ide.txt.
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	idebus=		[HW] (E)IDE subsystem - VLB/PCI bus speed
872
			See Documentation/ide/ide.txt.
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874
	idle=		[X86]
875
			Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
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			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.
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			idle=halt. Halt is forced to be used for CPU idle.
			In such case C2/C3 won't be used again.
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			idle=nomwait. Disable mwait for CPU C-states
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	ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
			Claim all unknown PCI IDE storage controllers.

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

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	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]

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	iommu=		[x86]
		off
		force
		noforce
		biomerge
		panic
		nopanic
		merge
		nomerge
		forcesac
		soft


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	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.
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		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.
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		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.
949

950
	io_delay=	[X86-32,X86-64] I/O delay method
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		0x80
			Standard port 0x80 based delay
		0xed
			Alternate port 0xed based delay (needed on some systems)
955
		udelay
956 957 958
			Simple two microseconds delay
		none
			No delay
959

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

	ip=		[IP_PNP]
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			See Documentation/filesystems/nfsroot.txt.
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	ip2=		[HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
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			See comment before ip2_setup() in
			drivers/char/ip2/ip2base.c.
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	ips=		[HW,SCSI] Adaptec / IBM ServeRAID controller
			See header of drivers/scsi/ips.c.

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	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>....

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	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.

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	isapnp=		[ISAPNP]
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			Format: <RDP>,<reset>,<pci_scan>,<verbosity>
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	isolcpus=	[KNL,SMP] Isolate CPUs from the general scheduler.
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			Format:
			<cpu number>,...,<cpu number>
			or
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			<cpu number>-<cpu number>
			(must be a positive range in ascending order)
1000 1001
			or a mixture
			<cpu number>,...,<cpu number>-<cpu number>
1002

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			This option can be used to specify one or more CPUs
			to isolate from the general SMP balancing and scheduling
1005 1006
			algorithms. You can move a process onto or off an
			"isolated" CPU via the CPU affinity syscalls or cpuset.
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			<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
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			alternative -- manually setting the CPU mask of all
			tasks in the system -- can cause problems and
			suboptimal load balancer performance.
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	iucv=		[HW,NET]
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	js=		[HW,JOY] Analog joystick
			See Documentation/input/joystick.txt.

1020
	kernelcore=nn[KMG]	[KNL,X86-32,IA-64,PPC,X86-64] This parameter
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			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.

1036
	movablecore=nn[KMG]	[KNL,X86-32,IA-64,PPC,X86-64] This parameter
1037 1038 1039 1040 1041 1042 1043 1044 1045
			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.

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	keepinitrd	[HW,ARM]

1048
	kstack=N	[X86-32,X86-64] Print N words from the kernel stack
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			in oops dumps.

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	kgdboc=		[HW] kgdb over consoles.
			Requires a tty driver that supports console polling.
			(only serial suported for now)
			Format: <serial_device>[,baud]

1056 1057 1058 1059
	kmac=		[MIPS] korina ethernet MAC address.
			Configure the RouterBoard 532 series on-chip
			Ethernet adapter MAC address.

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	l2cr=		[PPC]

1062 1063
	l3cr=		[PPC]

1064
	lapic		[X86-32,APIC] Enable the local APIC even if BIOS
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			disabled it.
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1067
	lapic_timer_c2_ok	[X86-32,x86-64,APIC] trust the local apic timer in
1068 1069
			C2 power state.

1070 1071 1072 1073 1074 1075 1076 1077
	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.

1078 1079 1080 1081
	libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
			when set.
			Format: <int>

1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113
	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.

1114 1115 1116
			* nohrst, nosrst, norst: suppress hard, soft
                          and both resets.

1117 1118 1119
			If there are multiple matching configurations changing
			the same attribute, the last one is used.

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	load_ramdisk=	[RAM] List of ramdisks to load from floppy
			See Documentation/ramdisk.txt.

1123 1124
	lockd.nlm_grace_period=P  [NFS] Assign grace period.
			Format: <integer>
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1126 1127 1128 1129 1130 1131 1132 1133
	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>
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	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.
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			Format: { n | nk | nM }
			n must be a power of two.  The default size
			is set in the kernel config file.
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	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.

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	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>

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	mac5380=	[HW,SCSI] Format:
			<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
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	machvec=	[IA64] Force the use of a particular machine-vector
			(machvec) in a generic kernel.
			Example: machvec=hpzx1_swiotlb
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	max_loop=	[LOOP] Maximum number of loopback devices that can
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			be mounted
			Format: <1-256>

	maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
1208 1209 1210 1211
			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.
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	max_addr=[KMG]	[KNL,BOOT,ia64] All physical memory greater than or
			equal to this physical address is ignored.

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	max_luns=	[SCSI] Maximum number of LUNs to probe.
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			Should be between 1 and 2^32-1.

	max_report_luns=
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			[SCSI] Maximum number of LUNs received.
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			Should be between 1 and 16384.

	mcatest=	[IA-64]

1225
	mce		[X86-32] Machine Check Exception
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	mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.txt
1228

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	md=		[HW] RAID subsystems devices and level
			See Documentation/md.txt.
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	mdacon=		[MDA]
			Format: <first>,<last>
			Specifies range of consoles to be captured by the MDA.
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	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.
1239
			[X86-32] Use together with memmap= to avoid physical
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			address space collisions. Without memmap= PCI devices
			could be placed at addresses belonging to unused RAM.

1243
	mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
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			memory.

1246 1247 1248 1249
	memchunk=nn[KMG]
			[KNL,SH] Allow user to override the default size for
			per-device physically contiguous DMA buffers.

1250
	memmap=exactmap	[KNL,X86-32,X86_64] Enable setting of an exact
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			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.
1267 1268 1269 1270
			Example: Exclude memory from 0x18690000-0x1869ffff
			         memmap=64K$0x18690000
			         or
			         memmap=0x10000$0x18690000
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1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294
	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.

1295
	memtest=	[KNL,X86] Enable memtest
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			Format: <integer>
			range: 0,4 : pattern number
			default : 0 <disable>

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	meye.*=		[HW] Set MotionEye Camera parameters
			See Documentation/video4linux/meye.txt.

1303 1304 1305 1306
	mfgpt_irq=	[IA-32] Specify the IRQ to use for the
			Multi-Function General Purpose Timers on AMD Geode
			platforms.

1307 1308 1309 1310 1311
	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.

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	mga=		[HW,DRM]

1314 1315 1316 1317 1318 1319 1320 1321
	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.

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	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>

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	MTD_Region=	[MTD] Format:
			<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
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	mtdparts=	[MTD]
1343
			See drivers/mtd/cmdlinepart.c.
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1345 1346 1347 1348 1349
	mtdset=		[ARM]
			ARM/S3C2412 JIVE boot control

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

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	mtouchusb.raw_coordinates=
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			[HW] Make the MicroTouch USB driver use raw coordinates
			('y', default) or cooked coordinates ('n')
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	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.
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			This usage is only documented in each driver source
			file if at all.

1376 1377 1378 1379 1380 1381 1382
	nf_conntrack.acct=
			[NETFILTER] Enable connection tracking flow accounting
			0 to disable accounting
			1 to enable accounting
			Default value depends on CONFIG_NF_CT_ACCT that is
			going to be removed in 2.6.29.

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	nfsaddrs=	[NFS]
1384
			See Documentation/filesystems/nfsroot.txt.
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	nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
1387
			See Documentation/filesystems/nfsroot.txt.
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1389 1390 1391 1392
	nfs.callback_tcpport=
			[NFS] set the TCP port on which the NFSv4 callback
			channel should listen.

1393 1394 1395 1396
	nfs.idmap_cache_timeout=
			[NFS] set the maximum lifetime for idmapper cache
			entries.

1397 1398 1399 1400 1401 1402 1403
	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.

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	nmi_debug=	[KNL,AVR32] Specify one or more actions to take
			when a NMI is triggered.
			Format: [state][,regs][,debounce][,die]

1408
	nmi_watchdog=	[KNL,BUGS=X86-32] Debugging features for SMP kernels
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1410
	no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
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			emulation library even if a 387 maths coprocessor
			is present.

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	noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
			caches in the slab allocator.  Saves per-node memory,
			but will impact performance.
1417

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	noalign		[KNL,ARM]

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	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]
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1428 1429
	nodelayacct	[KNL] Disable per-task delay accounting

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

1432 1433
	nodsp		[SH] Disable hardware DSP at boot time.

1434 1435
	noefi		[X86-32,X86-64] Disable EFI runtime services support.

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	noexec		[IA-64]

1438
	noexec		[X86-32,X86-64]
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			On X86-32 available only on PAE configured kernels.
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			noexec=on: enable non-executable mappings (default)
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			noexec=off: disable non-executable mappings

	noexec32	[X86-64]
			This affects only 32-bit executables.
			noexec32=on: enable non-executable mappings (default)
				read doesn't imply executable mappings
			noexec32=off: disable non-executable mappings
				read implies executable mappings
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1450 1451
	nofpu		[SH] Disable hardware FPU at boot time.

1452
	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
1453 1454
			register save and restore. The kernel will only save
			legacy floating-point registers on task switch.
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	noclflush	[BUGS=X86] Don't use the CLFLUSH instruction

1458
	nohlt		[BUGS=ARM,SH]
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1460
	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
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			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.

1471 1472 1473 1474
	nohz=		[KNL] Boottime enable/disable dynamic ticks
			Valid arguments: on, off
			Default: on

1475
	noirqdebug	[X86-32] Disables the code which attempts to detect and
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			disable unhandled interrupt sources.

1478
	no_timer_check	[X86-32,X86_64,APIC] Disables the code which tests for
1479 1480
			broken timer IRQ sources.

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	noisapnp	[ISAPNP] Disables ISA PnP code.

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

	nointroute	[IA-64]

1488 1489
	nojitter	[IA64] Disables jitter checking for ITC timers.

1490
	nolapic		[X86-32,APIC] Do not enable or use the local APIC.
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1492
	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
1493

1494 1495
	nox2apic	[X86-64,APIC] Do not enable x2APIC mode.

1496 1497 1498 1499
	x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
			default x2apic cluster mode on platforms
			supporting x2apic.

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	noltlbs		[PPC] Do not use large page/tlb entries for kernel
			lowmem mapping on PPC40x.

1503 1504
	nomca		[IA-64] Disable machine check abort handling

1505
	nomce		[X86-32] Machine Check Exception
1506

1507 1508 1509
	nomfgpt		[X86-32] Disable Multi-Function General Purpose
			Timer usage (for AMD Geode machines).

1510
	noreplace-paravirt	[X86-32,PV_OPS] Don't patch paravirt_ops
1511

1512
	noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
1513 1514
			with UP alternatives

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	noresidual	[PPC] Don't use residual data on PReP machines.

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	noresume	[SWSUSP] Disables resume and restores original swap
			space.

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	no-scroll	[VGA] Disables scrollback.
			This is required for the Braillex ib80-piezo Braille
			reader made by F.H. Papenmeier (Germany).

	nosbagart	[IA-64]

1526
	nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1527

1528 1529
	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
			and disable the IO APIC.  legacy for "maxcpus=0".
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1531 1532
	nosoftlockup	[KNL] Disable the soft-lockup detector.

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	nosync		[HW,M68K] Disables sync negotiation for all devices.

1535
	notsc		[BUGS=X86-32] Disable Time Stamp Counter
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	nousb		[USB] Disable the USB subsystem

	nowb		[ARM]
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1541 1542 1543 1544
	nptcg=		[IA64] Override max number of concurrent global TLB
			purges which is reported from either PAL_VM_SUMMARY or
			SAL PALO.

1545 1546 1547 1548 1549
	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.

1550 1551
	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.

1552 1553 1554 1555 1556 1557 1558
	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!

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

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	pas2=		[HW,OSS] Format:
			<io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>

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	pas16=		[HW,SCSI]
			See header of drivers/scsi/pas16.c.

1607 1608 1609 1610 1611
	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.

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	pcbit=		[HW,ISDN]

	pcd.		[PARIDE]
			See header of drivers/block/paride/pcd.c.
			See also Documentation/paride.txt.

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	pci=option[,option...]	[PCI] various PCI subsystem options:
1619
		off		[X86] don't probe for the PCI bus
1620
		bios		[X86-32] force use of PCI BIOS, don't access
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				the hardware directly. Use this if your machine
				has a non-standard PCI host bridge.
1623
		nobios		[X86-32] disallow use of PCI BIOS, only direct
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				hardware access methods are allowed. Use this
				if you experience crashes upon bootup and you
				suspect they are caused by the BIOS.
1627
		conf1		[X86] Force use of PCI Configuration
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				Mechanism 1.
1629
		conf2		[X86] Force use of PCI Configuration
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				Mechanism 2.
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1631 1632 1633
		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.
1634 1635
		nodomains	[PCI] Disable support for multiple PCI
				root domains (aka PCI segments, in ACPI-speak).
1636
		nommconf	[X86-32,X86_64] Disable use of MMCONFIG for PCI
1637
				Configuration
1638 1639 1640
		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.
1641
		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
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				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.
1649
		rom		[X86] Assign address space to expansion ROMs.
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				Use with caution as certain devices share
				address decoders between ROMs and other
				resources.
1653
		norom		[X86] Do not assign address space to
1654 1655
				expansion ROMs that do not already have
				BIOS assigned address ranges.
1656
		irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
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				assigned automatically to PCI devices. You can
				make the kernel exclude IRQs of your ISA cards
				this way.
1660
		pirqaddr=0xAAAAA	[X86] Specify the physical address
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				of the PIRQ table (normally generated
				by the BIOS) if it is outside the
				F0000h-100000h range.
1664
		lastbus=N	[X86] Scan all buses thru bus #N. Can be
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				useful if the kernel is unable to find your
				secondary buses and you want to tell it
				explicitly which ones they are.
1668
		assign-busses	[X86] Always assign all PCI bus
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				numbers ourselves, overriding
				whatever the firmware may have done.
1671
		usepirqmask	[X86] Honor the possible IRQ mask stored
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				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.
1677
		noacpi		[X86] Do not use ACPI for IRQ routing
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				or for PCI scanning.
1679
		use_crs		[X86] Use _CRS for PCI resource
1680
				allocation.
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1681 1682 1683 1684
		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.
1685 1686
		skip_isa_align	[X86] do not align io start addr, so can
				handle more pci cards
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		firmware	[ARM] Do not re-enumerate the bus but instead
				just use the configuration from the
				bootloader. This is currently used on
				IXP2000 systems where the bus has to be
				configured a certain way for adjunct CPUs.
1692 1693 1694 1695 1696
		noearly		[X86] Don't do any early type 1 scanning.
				This might help on some broken boards which
				machine check when some devices' config space
				is read. But various workarounds are disabled
				and some IOMMU drivers will not work.
1697 1698 1699 1700
		bfsort		Sort PCI devices into breadth-first order.
				This sorting is done to get a device
				order compatible with older (<= 2.4) kernels.
		nobfsort	Don't sort PCI devices into breadth-first order.
1701 1702 1703 1704 1705 1706
		cbiosize=nn[KMG]	The fixed amount of bus space which is
				reserved for the CardBus bridge's IO window.
				The default value is 256 bytes.
		cbmemsize=nn[KMG]	The fixed amount of bus space which is
				reserved for the CardBus bridge's memory
				window. The default value is 64 megabytes.
1707

1708 1709 1710 1711 1712 1713
	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
			Management.
		off	Disable ASPM.
		force	Enable ASPM even on devices that claim not to support it.
			WARNING: Forcing ASPM on may cause system lockups.

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	pcmv=		[HW,PCMCIA] BadgePAD 4

	pd.		[PARIDE]
			See Documentation/paride.txt.

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

	pf.		[PARIDE]
			See Documentation/paride.txt.

	pg.		[PARIDE]
			See Documentation/paride.txt.

	pirq=		[SMP,APIC] Manual mp-table setup
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			See Documentation/x86/i386/IO-APIC.txt.
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	plip=		[PPT,NET] Parallel port network link
			Format: { parport<nr> | timid | 0 }
			See also Documentation/parport.txt.

1737 1738 1739 1740
	pmtmr=		[X86] Manual setup of pmtmr I/O Port. 
			Override pmtimer IOPort with a hex value.
			e.g. pmtmr=0x508

1741 1742 1743 1744
	pnp.debug	[PNP]
			Enable PNP debug messages.  This depends on the
			CONFIG_PNP_DEBUG_MESSAGES option.

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	pnpacpi=	[ACPI]
			{ off }

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

	pnp_reserve_irq=
			[ISAPNP] Exclude IRQs for the autoconfiguration

	pnp_reserve_dma=
			[ISAPNP] Exclude DMAs for the autoconfiguration

	pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
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			Ranges are in pairs (I/O port base and size).
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	pnp_reserve_mem=
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			[ISAPNP] Exclude memory regions for the
			autoconfiguration.
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			Ranges are in pairs (memory base and size).

1765 1766 1767 1768 1769
	dynamic_printk
			Enables pr_debug()/dev_dbg() calls if
			CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
			be switched on/off via <debugfs>/dynamic_printk/modules

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	print-fatal-signals=
			[KNL] debug: print fatal signals
			print-fatal-signals=1: print segfault info to
			the kernel console.
			default: off.

1776 1777 1778
	printk.time=	Show timing data prefixed to each printk message line
			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)

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	profile=	[KNL] Enable kernel profiling via /proc/profile
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			Format: [schedule,]<number>
			Param: "schedule" - profile schedule points.
			Param: <number> - step/bucket size as a power of 2 for
				statistical time based profiling.
1784 1785
			Param: "sleep" - profile D-state sleeping (millisecs).
				Requires CONFIG_SCHEDSTATS
1786
			Param: "kvm" - profile VM exits.
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	processor.max_cstate=	[HW,ACPI]
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			Limit processor to maximum C-state
			max_cstate=9 overrides any DMI blacklist limit.

1792 1793 1794 1795
	processor.nocst	[HW,ACPI]
			Ignore the _CST method to determine C-states,
			instead using the legacy FADT method

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	prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk
			before loading.
			See Documentation/ramdisk.txt.

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	psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
			probe for; one of (bare|imps|exps|lifebook|any).
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	psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
			per second.
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	psmouse.resetafter=	[HW,MOUSE]
			Try to reset the device after so many bad packets
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			(0 = never).
	psmouse.resolution=
			[HW,MOUSE] Set desired mouse resolution, in dpi.
	psmouse.smartscroll=
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			[HW,MOUSE] Controls Logitech smartscroll autorepeat.
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			0 = disabled, 1 = enabled (default).

	pss=		[HW,OSS] Personal Sound System (ECHO ESC614)
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			Format:
			<io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
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	pt.		[PARIDE]
			See Documentation/paride.txt.

1820 1821 1822 1823
	pty.legacy_count=
			[KNL] Number of legacy pty's. Overwrites compiled-in
			default number.

1824
	quiet		[KNL] Disable most log messages
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	r128=		[HW,DRM]

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

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	ramdisk_blocksize=	[RAM]
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			See Documentation/ramdisk.txt.
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	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
			See Documentation/ramdisk.txt.

1837 1838 1839
	rcupdate.blimit=	[KNL,BOOT]
			Set maximum number of finished RCU callbacks to process
			in one batch.
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1841 1842
	rcupdate.qhimark=	[KNL,BOOT]
			Set threshold of queued
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			RCU callbacks over which batch limiting is disabled.

1845 1846 1847
	rcupdate.qlowmark=	[KNL,BOOT]
			Set threshold of queued RCU callbacks below which
			batch limiting is re-enabled.
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1849 1850 1851 1852 1853
	rdinit=		[KNL]
			Format: <full_path>
			Run specified binary instead of /init from the ramdisk,
			used for early userspace startup. See initrd.

1854
	reboot=		[BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
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			Format: <reboot_mode>[,<reboot_mode2>[,...]]
1856
			See arch/*/kernel/reboot.c or arch/*/kernel/process.c			
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1858 1859 1860 1861
	relax_domain_level=
			[KNL, SMP] Set scheduler's default relax_domain_level.
			See Documentation/cpusets.txt.

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	reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area

1864
	reservetop=	[X86-32]
1865 1866 1867 1868
			Format: nn[KMG]
			Reserves a hole at the top of the kernel virtual
			address space.

1869 1870 1871
	reset_devices	[KNL] Force drivers to reset the underlying device
			during initialization.

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	resume=		[SWSUSP]
			Specify the partition device for software suspend
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1875 1876 1877 1878 1879 1880
	resume_offset=	[SWSUSP]
			Specify the offset from the beginning of the partition
			given by "resume=" at which the swap header is located,
			in <PAGE_SIZE> units (needed only for swap files).
			See  Documentation/power/swsusp-and-swap-files.txt

1881 1882
	retain_initrd	[RAM] Keep initrd memory after extraction

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	rhash_entries=	[KNL,NET]
			Set number of hash buckets for route cache

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

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

	root=		[KNL] Root filesystem

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

	rootflags=	[KNL] Set root filesystem mount option string

	rootfstype=	[KNL] Set root filesystem type

1900 1901 1902 1903
	rootwait	[KNL] Wait (indefinitely) for root device to show up.
			Useful for devices that are detected asynchronously
			(e.g. USB and MMC devices).

1904 1905 1906 1907 1908 1909 1910 1911 1912
	root_plug.vendor_id=
			[ROOTPLUG] Override the default vendor ID

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

	root_plug.debug=
			[ROOTPLUG] Enable debugging output

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	rw		[KNL] Mount root device read-write on boot

	S		[KNL] Run init in single mode

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

	sbni=		[NET] Granch SBNI12 leased line adapter
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	sc1200wdt=	[HW,WDT] SC1200 WDT (watchdog) driver
			Format: <io>[,<timeout>[,<isapnp>]]

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

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

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

1936 1937 1938 1939 1940 1941 1942
	scsi_logging_level=	[SCSI] a bit mask of logging levels
			See drivers/scsi/scsi_logging.h for bits.  Also
			settable via sysctl at dev.scsi.logging_level
			(/proc/sys/dev/scsi/logging_level).
			There is also a nice 'scsi_logging_level' script in the
			S390-tools package, available for download at
			http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
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1944 1945 1946 1947 1948
	scsi_mod.scan=	[SCSI] sync (default) scans SCSI busses as they are
			discovered.  async scans them in kernel threads,
			allowing boot to proceed.  none ignores them, expecting
			user space to do the scan.

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	selinux		[SELINUX] Disable or enable SELinux at boot time.
			Format: { "0" | "1" }
			See security/selinux/Kconfig help text.
			0 -- disable.
			1 -- enable.
			Default value is set via kernel config option.
			If enabled at boot time, /selinux/disable can be used
			later to disable prior to initial policy load.

1958 1959
	selinux_compat_net =
			[SELINUX] Set initial selinux_compat_net flag value.
1960 1961 1962 1963 1964 1965
                        Format: { "0" | "1" }
                        0 -- use new secmark-based packet controls
                        1 -- use legacy packet controls
                        Default value is 0 (preferred).
                        Value can be changed at runtime via
                        /selinux/compat_net.
1966

1967
	serialnumber	[BUGS=X86-32]
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	shapers=	[NET]
			Maximal number of shapers.
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	show_msr=	[x86] show boot-time MSR settings
			Format: { <integer> }
			Show boot-time (BIOS-initialized) MSR settings.
			The parameter means the number of CPUs to show,
			for example 1 means boot CPU only.

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	sim710=		[SCSI,HW]
			See header of drivers/scsi/sim710.c.

	simeth=		[IA-64]
	simscsi=
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	slram=		[HW,MTD]

1986 1987 1988 1989 1990 1991 1992
	slub_debug[=options[,slabs]]	[MM, SLUB]
			Enabling slub_debug allows one to determine the
			culprit if slab objects become corrupted. Enabling
			slub_debug can create guard zones around objects and
			may poison objects when not in use. Also tracks the
			last alloc / free. For more information see
			Documentation/vm/slub.txt.
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	slub_max_order= [MM, SLUB]
1995 1996 1997 1998
			Determines the maximum allowed order for slabs.
			A high setting may cause OOMs due to memory
			fragmentation. For more information see
			Documentation/vm/slub.txt.
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	slub_min_objects=	[MM, SLUB]
2001 2002 2003 2004 2005 2006
			The minimum number of objects per slab. SLUB will
			increase the slab order up to slub_max_order to
			generate a sufficiently large slab able to contain
			the number of objects indicated. The higher the number
			of objects the smaller the overhead of tracking slabs
			and the less frequently locks need to be acquired.
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			For more information see Documentation/vm/slub.txt.

	slub_min_order=	[MM, SLUB]
			Determines the mininum page order for slabs. Must be
2011
			lower than slub_max_order.
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			For more information see Documentation/vm/slub.txt.

	slub_nomerge	[MM, SLUB]
2015
			Disable merging of slabs with similar size. May be
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			necessary if there is some reason to distinguish
2017 2018
			allocs to different slabs. Debug options disable
			merging on their own.
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			For more information see Documentation/vm/slub.txt.

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	smart2=		[HW]
			Format: <io1>[,<io2>[,...,<io8>]]

2024
	smp-alt-once	[X86-32,SMP] On a hotplug CPU system, only
2025 2026
			attempt to substitute SMP alternatives once at boot.

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	smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
	smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
	smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
	smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
	smsc-ircc2.ircc_irq=	[HW] IRQ line
	smsc-ircc2.ircc_dma=	[HW] DMA channel
	smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
				0: Toshiba Satellite 1800 (GP data pin select)
				1: Fast pin select (default)
				2: ATC IRMode

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	snd-ad1816a=	[HW,ALSA]

	snd-ad1848=	[HW,ALSA]

	snd-ali5451=	[HW,ALSA]

	snd-als100=	[HW,ALSA]

	snd-als4000=	[HW,ALSA]

	snd-azt2320=	[HW,ALSA]

	snd-cmi8330=	[HW,ALSA]

	snd-cmipci=	[HW,ALSA]

	snd-cs4231=	[HW,ALSA]

	snd-cs4232=	[HW,ALSA]

	snd-cs4236=	[HW,ALSA]

	snd-cs4281=	[HW,ALSA]

	snd-cs46xx=	[HW,ALSA]

	snd-dt019x=	[HW,ALSA]

	snd-dummy=	[HW,ALSA]

	snd-emu10k1=	[HW,ALSA]

	snd-ens1370=	[HW,ALSA]

	snd-ens1371=	[HW,ALSA]

	snd-es968=	[HW,ALSA]

	snd-es1688=	[HW,ALSA]

	snd-es18xx=	[HW,ALSA]

	snd-es1938=	[HW,ALSA]

	snd-es1968=	[HW,ALSA]

	snd-fm801=	[HW,ALSA]

	snd-gusclassic=	[HW,ALSA]

	snd-gusextreme=	[HW,ALSA]

	snd-gusmax=	[HW,ALSA]

	snd-hdsp=	[HW,ALSA]

	snd-ice1712=	[HW,ALSA]

	snd-intel8x0=	[HW,ALSA]

	snd-interwave=	[HW,ALSA]

	snd-interwave-stb=
			[HW,ALSA]

	snd-korg1212=	[HW,ALSA]

	snd-maestro3=	[HW,ALSA]

	snd-mpu401=	[HW,ALSA]

	snd-mtpav=	[HW,ALSA]

	snd-nm256=	[HW,ALSA]

	snd-opl3sa2=	[HW,ALSA]

	snd-opti92x-ad1848=
			[HW,ALSA]

	snd-opti92x-cs4231=
			[HW,ALSA]

	snd-opti93x=	[HW,ALSA]

	snd-pmac=	[HW,ALSA]

	snd-rme32=	[HW,ALSA]

	snd-rme96=	[HW,ALSA]

	snd-rme9652=	[HW,ALSA]

	snd-sb8=	[HW,ALSA]

	snd-sb16=	[HW,ALSA]

	snd-sbawe=	[HW,ALSA]

	snd-serial=	[HW,ALSA]

	snd-sgalaxy=	[HW,ALSA]

	snd-sonicvibes=	[HW,ALSA]

	snd-sun-amd7930=
			[HW,ALSA]

	snd-sun-cs4231=	[HW,ALSA]

	snd-trident=	[HW,ALSA]

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

	snd-via82xx=	[HW,ALSA]

	snd-virmidi=	[HW,ALSA]

	snd-wavefront=	[HW,ALSA]

	snd-ymfpci=	[HW,ALSA]
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	softlockup_panic=
			[KNL] Should the soft-lockup detector generate panics.

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	sonypi.*=	[HW] Sony Programmable I/O Control Device driver
			See Documentation/sonypi.txt

	specialix=	[HW,SERIAL] Specialix multi-serial port adapter
			See Documentation/specialix.txt.

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

	sscape=		[HW,OSS]
			Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
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	st=		[HW,SCSI] SCSI tape parameters (buffers, etc.)
			See Documentation/scsi/st.txt.

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

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

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

2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208
	sunrpc.pool_mode=
			[NFS]
			Control how the NFS server code allocates CPUs to
			service thread pools.  Depending on how many NICs
			you have and where their interrupts are bound, this
			option will affect which CPUs will do NFS serving.
			Note: this parameter cannot be changed while the
			NFS server is running.

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

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	swiotlb=	[IA-64] Number of I/O TLB slabs
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	switches=	[HW,M68k]

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

2216 2217 2218 2219 2220 2221
	sysrq_always_enabled
			[KNL]
			Ignore sysrq setting - this boot parameter will
			neutralize any effect of /proc/sys/kernel/sysrq.
			Useful for debugging.

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	t128=		[HW,SCSI]
			See header of drivers/scsi/t128.c.

	tdfx=		[HW,DRM]

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	test_suspend=	[SUSPEND]
			Specify "mem" (for Suspend-to-RAM) or "standby" (for
			standby suspend) as the system sleep state to briefly
			enter during system startup.  The system is woken from
			this state using a wakeup-capable RTC alarm.

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	thash_entries=	[KNL,NET]
			Set number of hash buckets for TCP connection

2236 2237 2238 2239
	thermal.act=	[HW,ACPI]
			-1: disable all active trip points in all thermal zones
			<degrees C>: override all lowest active trip points

2240 2241
	thermal.crt=	[HW,ACPI]
			-1: disable all critical trip points in all thermal zones
2242
			<degrees C>: override all critical trip points
2243

2244 2245 2246 2247
	thermal.nocrt=	[HW,ACPI]
			Set to disable actions on ACPI thermal zone
			critical and hot trip points.

2248 2249 2250
	thermal.off=	[HW,ACPI]
			1: disable ACPI thermal control

2251 2252 2253 2254
	thermal.psv=	[HW,ACPI]
			-1: disable all passive trip points
			<degrees C>: override all passive trip points to this value

2255 2256 2257 2258 2259
	thermal.tzp=	[HW,ACPI]
			Specify global default ACPI thermal zone polling rate
			<deci-seconds>: poll all this frequency
			0: no polling (default)

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	tmscsim=	[HW,SCSI]
			See comment before function dc390_setup() in
			drivers/scsi/tmscsim.c.

	tp720=		[HW,PS2]

	trix=		[HW,OSS] MediaTrix AudioTrix Pro
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			Format:
			<io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>

	turbografx.map[2|3]=	[HW,JOY]
			TurboGraFX parallel port interface
			Format:
			<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
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			See also Documentation/input/joystick-parport.txt

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

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

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

2285 2286 2287 2288 2289 2290 2291 2292
	uhci-hcd.ignore_oc=
			[USB] Ignore overcurrent events (default N).
			Some badly-designed motherboards generate lots of
			bogus events, for ports that aren't wired to
			anything.  Set this parameter to avoid log spamming.
			Note that genuine overcurrent events won't be
			reported either.

2293 2294 2295 2296
	unknown_nmi_panic
			[X86-32,X86-64]
			Set unknown_nmi_panic=1 early on boot.

2297 2298 2299 2300 2301
	usbcore.autosuspend=
			[USB] The autosuspend time delay (in seconds) used
			for newly-detected USB devices (default 2).  This
			is the time required before an idle device will be
			autosuspended.  Devices for which the delay is set
2302
			to a negative value won't be autosuspended at all.
2303

2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322
	usbcore.usbfs_snoop=
			[USB] Set to log all usbfs traffic (default 0 = off).

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

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

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

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

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	usbhid.mousepoll=
			[USBHID] The interval which mice are to be polled at.
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2326 2327 2328
	add_efi_memmap	[EFI; x86-32,X86-64] Include EFI memory map in
			kernel's map of available physical RAM.

2329
	vdso=		[X86-32,SH,x86-64]
2330
			vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2331 2332 2333
			vdso=1: enable VDSO (default)
			vdso=0: disable VDSO mapping

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	vdso32=		[X86-32,X86-64]
			vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
			vdso32=1: enable 32-bit VDSO (default)
			vdso32=0: disable 32-bit VDSO mapping

2339 2340 2341
	vector=		[IA-64,SMP]
			vector=percpu: enable percpu vector domain

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	video=		[FB] Frame buffer configuration
			See Documentation/fb/modedb.txt.

2345
	vga=		[BOOT,X86-32] Select a particular video mode
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			See Documentation/x86/i386/boot.txt and
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			Documentation/svga.txt.
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			Use vga=ask for menu.
			This is actually a boot loader parameter; the value is
			passed to the kernel using a special protocol.

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	vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
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			size of <nn>. This can be used to increase the
			minimum size (128MB on x86). It can also be used to
			decrease the size and leave more room for directly
			mapped kernel RAM.

2358 2359
	vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
			Format: <command>
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2361 2362 2363 2364 2365
	vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
			Format: <command>

	vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
			Format: <command>
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	waveartist=	[HW,OSS]
			Format: <io>,<irq>,<dma>,<dma2>
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	wd33c93=	[HW,SCSI]
			See header of drivers/scsi/wd33c93.c.

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

	wdt=		[WDT] Watchdog
2377
			See Documentation/watchdog/wdt.txt.
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	xd=		[HW,XT] Original XT pre-IDE (RLL encoded) disks.
	xd_geo=		See header of drivers/block/xd.c.

	xirc2ps_cs=	[NET,PCMCIA]
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			Format:
			<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
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2386 2387 2388
	norandmaps	Don't use address space randomization
			Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space

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______________________________________________________________________
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TODO:

	Add documentation for ALSA options.
	Add more DRM drivers.