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Based on kernel version 3.9. Page generated on 2013-05-02 23:09 EST.

1	                          Kernel Parameters
2	                          ~~~~~~~~~~~~~~~~~
3	
4	The following is a consolidated list of the kernel parameters as implemented
5	(mostly) by the __setup() macro and sorted into English Dictionary order
6	(defined as ignoring all punctuation and sorting digits before letters in a
7	case insensitive manner), and with descriptions where known.
8	
9	Module parameters for loadable modules are specified only as the
10	parameter name with optional '=' and value as appropriate, such as:
11	
12		modprobe usbcore blinkenlights=1
13	
14	Module parameters for modules that are built into the kernel image
15	are specified on the kernel command line with the module name plus
16	'.' plus parameter name, with '=' and value if appropriate, such as:
17	
18		usbcore.blinkenlights=1
19	
20	Hyphens (dashes) and underscores are equivalent in parameter names, so
21		log_buf_len=1M print-fatal-signals=1
22	can also be entered as
23		log-buf-len=1M print_fatal_signals=1
24	
25	
26	This document may not be entirely up to date and comprehensive. The command
27	"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28	module. Loadable modules, after being loaded into the running kernel, also
29	reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30	parameters may be changed at runtime by the command
31	"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32	
33	The parameters listed below are only valid if certain kernel build options were
34	enabled and if respective hardware is present. The text in square brackets at
35	the beginning of each description states the restrictions within which a
36	parameter is applicable:
37	
38		ACPI	ACPI support is enabled.
39		AGP	AGP (Accelerated Graphics Port) is enabled.
40		ALSA	ALSA sound support is enabled.
41		APIC	APIC support is enabled.
42		APM	Advanced Power Management support is enabled.
43		ARM	ARM architecture is enabled.
44		AVR32	AVR32 architecture is enabled.
45		AX25	Appropriate AX.25 support is enabled.
46		BLACKFIN Blackfin architecture is enabled.
47		DRM	Direct Rendering Management support is enabled.
48		DYNAMIC_DEBUG Build in debug messages and enable them at runtime
49		EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled
50		EFI	EFI Partitioning (GPT) is enabled
51		EIDE	EIDE/ATAPI support is enabled.
52		EVM	Extended Verification Module
53		FB	The frame buffer device is enabled.
54		FTRACE	Function tracing enabled.
55		GCOV	GCOV profiling is enabled.
56		HW	Appropriate hardware is enabled.
57		IA-64	IA-64 architecture is enabled.
58		IMA     Integrity measurement architecture is enabled.
59		IOSCHED	More than one I/O scheduler is enabled.
60		IP_PNP	IP DHCP, BOOTP, or RARP is enabled.
61		IPV6	IPv6 support is enabled.
62		ISAPNP	ISA PnP code is enabled.
63		ISDN	Appropriate ISDN support is enabled.
64		JOY	Appropriate joystick support is enabled.
65		KGDB	Kernel debugger support is enabled.
66		KVM	Kernel Virtual Machine support is enabled.
67		LIBATA  Libata driver is enabled
68		LP	Printer support is enabled.
69		LOOP	Loopback device support is enabled.
70		M68k	M68k architecture is enabled.
71				These options have more detailed description inside of
72				Documentation/m68k/kernel-options.txt.
73		MDA	MDA console support is enabled.
74		MIPS	MIPS architecture is enabled.
75		MOUSE	Appropriate mouse support is enabled.
76		MSI	Message Signaled Interrupts (PCI).
77		MTD	MTD (Memory Technology Device) support is enabled.
78		NET	Appropriate network support is enabled.
79		NUMA	NUMA support is enabled.
80		NFS	Appropriate NFS support is enabled.
81		OSS	OSS sound support is enabled.
82		PV_OPS	A paravirtualized kernel is enabled.
83		PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.
84		PARISC	The PA-RISC architecture is enabled.
85		PCI	PCI bus support is enabled.
86		PCIE	PCI Express support is enabled.
87		PCMCIA	The PCMCIA subsystem is enabled.
88		PNP	Plug & Play support is enabled.
89		PPC	PowerPC architecture is enabled.
90		PPT	Parallel port support is enabled.
91		PS2	Appropriate PS/2 support is enabled.
92		RAM	RAM disk support is enabled.
93		S390	S390 architecture is enabled.
94		SCSI	Appropriate SCSI support is enabled.
95				A lot of drivers have their options described inside
96				the Documentation/scsi/ sub-directory.
97		SECURITY Different security models are enabled.
98		SELINUX SELinux support is enabled.
99		APPARMOR AppArmor support is enabled.
100		SERIAL	Serial support is enabled.
101		SH	SuperH architecture is enabled.
102		SMP	The kernel is an SMP kernel.
103		SPARC	Sparc architecture is enabled.
104		SWSUSP	Software suspend (hibernation) is enabled.
105		SUSPEND	System suspend states are enabled.
106		TPM	TPM drivers are enabled.
107		TS	Appropriate touchscreen support is enabled.
108		UMS	USB Mass Storage support is enabled.
109		USB	USB support is enabled.
110		USBHID	USB Human Interface Device support is enabled.
111		V4L	Video For Linux support is enabled.
112		VMMIO   Driver for memory mapped virtio devices is enabled.
113		VGA	The VGA console has been enabled.
114		VT	Virtual terminal support is enabled.
115		WDT	Watchdog support is enabled.
116		XT	IBM PC/XT MFM hard disk support is enabled.
117		X86-32	X86-32, aka i386 architecture is enabled.
118		X86-64	X86-64 architecture is enabled.
119				More X86-64 boot options can be found in
120				Documentation/x86/x86_64/boot-options.txt .
121		X86	Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
122		XEN	Xen support is enabled
123	
124	In addition, the following text indicates that the option:
125	
126		BUGS=	Relates to possible processor bugs on the said processor.
127		KNL	Is a kernel start-up parameter.
128		BOOT	Is a boot loader parameter.
129	
130	Parameters denoted with BOOT are actually interpreted by the boot
131	loader, and have no meaning to the kernel directly.
132	Do not modify the syntax of boot loader parameters without extreme
133	need or coordination with <Documentation/x86/boot.txt>.
134	
135	There are also arch-specific kernel-parameters not documented here.
136	See for example <Documentation/x86/x86_64/boot-options.txt>.
137	
138	Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
139	a trailing = on the name of any parameter states that that parameter will
140	be entered as an environment variable, whereas its absence indicates that
141	it will appear as a kernel argument readable via /proc/cmdline by programs
142	running once the system is up.
143	
144	The number of kernel parameters is not limited, but the length of the
145	complete command line (parameters including spaces etc.) is limited to
146	a fixed number of characters. This limit depends on the architecture
147	and is between 256 and 4096 characters. It is defined in the file
148	./include/asm/setup.h as COMMAND_LINE_SIZE.
149	
150	Finally, the [KMG] suffix is commonly described after a number of kernel
151	parameter values. These 'K', 'M', and 'G' letters represent the _binary_
152	multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
153	bytes respectively. Such letter suffixes can also be entirely omitted.
154	
155	
156		acpi=		[HW,ACPI,X86]
157				Advanced Configuration and Power Interface
158				Format: { force | off | strict | noirq | rsdt }
159				force -- enable ACPI if default was off
160				off -- disable ACPI if default was on
161				noirq -- do not use ACPI for IRQ routing
162				strict -- Be less tolerant of platforms that are not
163					strictly ACPI specification compliant.
164				rsdt -- prefer RSDT over (default) XSDT
165				copy_dsdt -- copy DSDT to memory
166	
167				See also Documentation/power/runtime_pm.txt, pci=noacpi
168	
169		acpi_rsdp=	[ACPI,EFI,KEXEC]
170				Pass the RSDP address to the kernel, mostly used
171				on machines running EFI runtime service to boot the
172				second kernel for kdump.
173	
174		acpi_apic_instance=	[ACPI, IOAPIC]
175				Format: <int>
176				2: use 2nd APIC table, if available
177				1,0: use 1st APIC table
178				default: 0
179	
180		acpi_backlight=	[HW,ACPI]
181				acpi_backlight=vendor
182				acpi_backlight=video
183				If set to vendor, prefer vendor specific driver
184				(e.g. thinkpad_acpi, sony_acpi, etc.) instead
185				of the ACPI video.ko driver.
186	
187		acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
188		acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
189				Format: <int>
190				CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
191				debug output.  Bits in debug_layer correspond to a
192				_COMPONENT in an ACPI source file, e.g.,
193				    #define _COMPONENT ACPI_PCI_COMPONENT
194				Bits in debug_level correspond to a level in
195				ACPI_DEBUG_PRINT statements, e.g.,
196				    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
197				The debug_level mask defaults to "info".  See
198				Documentation/acpi/debug.txt for more information about
199				debug layers and levels.
200	
201				Enable processor driver info messages:
202				    acpi.debug_layer=0x20000000
203				Enable PCI/PCI interrupt routing info messages:
204				    acpi.debug_layer=0x400000
205				Enable AML "Debug" output, i.e., stores to the Debug
206				object while interpreting AML:
207				    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
208				Enable all messages related to ACPI hardware:
209				    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
210	
211				Some values produce so much output that the system is
212				unusable.  The "log_buf_len" parameter may be useful
213				if you need to capture more output.
214	
215		acpi_irq_balance [HW,ACPI]
216				ACPI will balance active IRQs
217				default in APIC mode
218	
219		acpi_irq_nobalance [HW,ACPI]
220				ACPI will not move active IRQs (default)
221				default in PIC mode
222	
223		acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
224				Format: <irq>,<irq>...
225	
226		acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
227				use by PCI
228				Format: <irq>,<irq>...
229	
230		acpi_no_auto_ssdt	[HW,ACPI] Disable automatic loading of SSDT
231	
232		acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
233				Format: To spoof as Windows 98: ="Microsoft Windows"
234	
235		acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
236				acpi_osi="string1"	# add string1 -- only one string
237				acpi_osi="!string2"	# remove built-in string2
238				acpi_osi=		# disable all strings
239	
240		acpi_pm_good	[X86]
241				Override the pmtimer bug detection: force the kernel
242				to assume that this machine's pmtimer latches its value
243				and always returns good values.
244	
245		acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
246				Format: { level | edge | high | low }
247	
248		acpi_serialize	[HW,ACPI] force serialization of AML methods
249	
250		acpi_skip_timer_override [HW,ACPI]
251				Recognize and ignore IRQ0/pin2 Interrupt Override.
252				For broken nForce2 BIOS resulting in XT-PIC timer.
253	
254		acpi_sleep=	[HW,ACPI] Sleep options
255				Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
256					  old_ordering, nonvs, sci_force_enable }
257				See Documentation/power/video.txt for information on
258				s3_bios and s3_mode.
259				s3_beep is for debugging; it makes the PC's speaker beep
260				as soon as the kernel's real-mode entry point is called.
261				s4_nohwsig prevents ACPI hardware signature from being
262				used during resume from hibernation.
263				old_ordering causes the ACPI 1.0 ordering of the _PTS
264				control method, with respect to putting devices into
265				low power states, to be enforced (the ACPI 2.0 ordering
266				of _PTS is used by default).
267				nonvs prevents the kernel from saving/restoring the
268				ACPI NVS memory during suspend/hibernation and resume.
269				sci_force_enable causes the kernel to set SCI_EN directly
270				on resume from S1/S3 (which is against the ACPI spec,
271				but some broken systems don't work without it).
272	
273		acpi_use_timer_override [HW,ACPI]
274				Use timer override. For some broken Nvidia NF5 boards
275				that require a timer override, but don't have HPET
276	
277		acpi_enforce_resources=	[ACPI]
278				{ strict | lax | no }
279				Check for resource conflicts between native drivers
280				and ACPI OperationRegions (SystemIO and SystemMemory
281				only). IO ports and memory declared in ACPI might be
282				used by the ACPI subsystem in arbitrary AML code and
283				can interfere with legacy drivers.
284				strict (default): access to resources claimed by ACPI
285				is denied; legacy drivers trying to access reserved
286				resources will fail to bind to device using them.
287				lax: access to resources claimed by ACPI is allowed;
288				legacy drivers trying to access reserved resources
289				will bind successfully but a warning message is logged.
290				no: ACPI OperationRegions are not marked as reserved,
291				no further checks are performed.
292	
293		add_efi_memmap	[EFI; X86] Include EFI memory map in
294				kernel's map of available physical RAM.
295	
296		agp=		[AGP]
297				{ off | try_unsupported }
298				off: disable AGP support
299				try_unsupported: try to drive unsupported chipsets
300					(may crash computer or cause data corruption)
301	
302		ALSA		[HW,ALSA]
303				See Documentation/sound/alsa/alsa-parameters.txt
304	
305		alignment=	[KNL,ARM]
306				Allow the default userspace alignment fault handler
307				behaviour to be specified.  Bit 0 enables warnings,
308				bit 1 enables fixups, and bit 2 sends a segfault.
309	
310		align_va_addr=	[X86-64]
311				Align virtual addresses by clearing slice [14:12] when
312				allocating a VMA at process creation time. This option
313				gives you up to 3% performance improvement on AMD F15h
314				machines (where it is enabled by default) for a
315				CPU-intensive style benchmark, and it can vary highly in
316				a microbenchmark depending on workload and compiler.
317	
318				32: only for 32-bit processes
319				64: only for 64-bit processes
320				on: enable for both 32- and 64-bit processes
321				off: disable for both 32- and 64-bit processes
322	
323		amd_iommu=	[HW,X86-64]
324				Pass parameters to the AMD IOMMU driver in the system.
325				Possible values are:
326				fullflush - enable flushing of IO/TLB entries when
327					    they are unmapped. Otherwise they are
328					    flushed before they will be reused, which
329					    is a lot of faster
330				off	  - do not initialize any AMD IOMMU found in
331					    the system
332				force_isolation - Force device isolation for all
333						  devices. The IOMMU driver is not
334						  allowed anymore to lift isolation
335						  requirements as needed. This option
336						  does not override iommu=pt
337	
338		amd_iommu_dump=	[HW,X86-64]
339				Enable AMD IOMMU driver option to dump the ACPI table
340				for AMD IOMMU. With this option enabled, AMD IOMMU
341				driver will print ACPI tables for AMD IOMMU during
342				IOMMU initialization.
343	
344		amijoy.map=	[HW,JOY] Amiga joystick support
345				Map of devices attached to JOY0DAT and JOY1DAT
346				Format: <a>,<b>
347				See also Documentation/input/joystick.txt
348	
349		analog.map=	[HW,JOY] Analog joystick and gamepad support
350				Specifies type or capabilities of an analog joystick
351				connected to one of 16 gameports
352				Format: <type1>,<type2>,..<type16>
353	
354		apc=		[HW,SPARC]
355				Power management functions (SPARCstation-4/5 + deriv.)
356				Format: noidle
357				Disable APC CPU standby support. SPARCstation-Fox does
358				not play well with APC CPU idle - disable it if you have
359				APC and your system crashes randomly.
360	
361		apic=		[APIC,X86-32] Advanced Programmable Interrupt Controller
362				Change the output verbosity whilst booting
363				Format: { quiet (default) | verbose | debug }
364				Change the amount of debugging information output
365				when initialising the APIC and IO-APIC components.
366	
367		autoconf=	[IPV6]
368				See Documentation/networking/ipv6.txt.
369	
370		show_lapic=	[APIC,X86] Advanced Programmable Interrupt Controller
371				Limit apic dumping. The parameter defines the maximal
372				number of local apics being dumped. Also it is possible
373				to set it to "all" by meaning -- no limit here.
374				Format: { 1 (default) | 2 | ... | all }.
375				The parameter valid if only apic=debug or
376				apic=verbose is specified.
377				Example: apic=debug show_lapic=all
378	
379		apm=		[APM] Advanced Power Management
380				See header of arch/x86/kernel/apm_32.c.
381	
382		arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
383				Format: <io>,<irq>,<nodeID>
384	
385		ataflop=	[HW,M68k]
386	
387		atarimouse=	[HW,MOUSE] Atari Mouse
388	
389		atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
390				EzKey and similar keyboards
391	
392		atkbd.reset=	[HW] Reset keyboard during initialization
393	
394		atkbd.set=	[HW] Select keyboard code set
395				Format: <int> (2 = AT (default), 3 = PS/2)
396	
397		atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
398				keyboards
399	
400		atkbd.softraw=	[HW] Choose between synthetic and real raw mode
401				Format: <bool> (0 = real, 1 = synthetic (default))
402	
403		atkbd.softrepeat= [HW]
404				Use software keyboard repeat
405	
406		baycom_epp=	[HW,AX25]
407				Format: <io>,<mode>
408	
409		baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
410				Format: <io>,<mode>
411				See header of drivers/net/hamradio/baycom_par.c.
412	
413		baycom_ser_fdx=	[HW,AX25]
414				BayCom Serial Port AX.25 Modem (Full Duplex Mode)
415				Format: <io>,<irq>,<mode>[,<baud>]
416				See header of drivers/net/hamradio/baycom_ser_fdx.c.
417	
418		baycom_ser_hdx=	[HW,AX25]
419				BayCom Serial Port AX.25 Modem (Half Duplex Mode)
420				Format: <io>,<irq>,<mode>
421				See header of drivers/net/hamradio/baycom_ser_hdx.c.
422	
423		boot_delay=	Milliseconds to delay each printk during boot.
424				Values larger than 10 seconds (10000) are changed to
425				no delay (0).
426				Format: integer
427	
428		bootmem_debug	[KNL] Enable bootmem allocator debug messages.
429	
430		bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
431		bttv.radio=	Most important insmod options are available as
432				kernel args too.
433		bttv.pll=	See Documentation/video4linux/bttv/Insmod-options
434		bttv.tuner=
435	
436		bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
437				firmware feature for flushing multiple hpte entries
438				at a time.
439	
440		c101=		[NET] Moxa C101 synchronous serial card
441	
442		cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
443				Sometimes CPU hardware bugs make them report the cache
444				size incorrectly. The kernel will attempt work arounds
445				to fix known problems, but for some CPUs it is not
446				possible to determine what the correct size should be.
447				This option provides an override for these situations.
448	
449		ccw_timeout_log [S390]
450				See Documentation/s390/CommonIO for details.
451	
452		cgroup_disable= [KNL] Disable a particular controller
453				Format: {name of the controller(s) to disable}
454					{Currently supported controllers - "memory"}
455	
456		checkreqprot	[SELINUX] Set initial checkreqprot flag value.
457				Format: { "0" | "1" }
458				See security/selinux/Kconfig help text.
459				0 -- check protection applied by kernel (includes
460					any implied execute protection).
461				1 -- check protection requested by application.
462				Default value is set via a kernel config option.
463				Value can be changed at runtime via
464					/selinux/checkreqprot.
465	
466		cio_ignore=	[S390]
467				See Documentation/s390/CommonIO for details.
468	
469		clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
470				[Deprecated]
471				Forces specified clocksource (if available) to be used
472				when calculating gettimeofday(). If specified
473				clocksource is not available, it defaults to PIT.
474				Format: { pit | tsc | cyclone | pmtmr }
475	
476		clocksource=	Override the default clocksource
477				Format: <string>
478				Override the default clocksource and use the clocksource
479				with the name specified.
480				Some clocksource names to choose from, depending on
481				the platform:
482				[all] jiffies (this is the base, fallback clocksource)
483				[ACPI] acpi_pm
484				[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
485					pxa_timer,timer3,32k_counter,timer0_1
486				[AVR32] avr32
487				[X86-32] pit,hpet,tsc;
488					scx200_hrt on Geode; cyclone on IBM x440
489				[MIPS] MIPS
490				[PARISC] cr16
491				[S390] tod
492				[SH] SuperH
493				[SPARC64] tick
494				[X86-64] hpet,tsc
495	
496		clearcpuid=BITNUM [X86]
497				Disable CPUID feature X for the kernel. See
498				arch/x86/include/asm/cpufeature.h for the valid bit
499				numbers. Note the Linux specific bits are not necessarily
500				stable over kernel options, but the vendor specific
501				ones should be.
502				Also note that user programs calling CPUID directly
503				or using the feature without checking anything
504				will still see it. This just prevents it from
505				being used by the kernel or shown in /proc/cpuinfo.
506				Also note the kernel might malfunction if you disable
507				some critical bits.
508	
509		cma=nn[MG]	[ARM,KNL]
510				Sets the size of kernel global memory area for contiguous
511				memory allocations. For more information, see
512				include/linux/dma-contiguous.h
513	
514		cmo_free_hint=	[PPC] Format: { yes | no }
515				Specify whether pages are marked as being inactive
516				when they are freed.  This is used in CMO environments
517				to determine OS memory pressure for page stealing by
518				a hypervisor.
519				Default: yes
520	
521		coherent_pool=nn[KMG]	[ARM,KNL]
522				Sets the size of memory pool for coherent, atomic dma
523				allocations, by default set to 256K.
524	
525		code_bytes	[X86] How many bytes of object code to print
526				in an oops report.
527				Range: 0 - 8192
528				Default: 64
529	
530		com20020=	[HW,NET] ARCnet - COM20020 chipset
531				Format:
532				<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
533	
534		com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
535				Format: <io>[,<irq>]
536	
537		com90xx=	[HW,NET]
538				ARCnet - COM90xx chipset (memory-mapped buffers)
539				Format: <io>[,<irq>[,<memstart>]]
540	
541		condev=		[HW,S390] console device
542		conmode=
543	
544		console=	[KNL] Output console device and options.
545	
546			tty<n>	Use the virtual console device <n>.
547	
548			ttyS<n>[,options]
549			ttyUSB0[,options]
550				Use the specified serial port.  The options are of
551				the form "bbbbpnf", where "bbbb" is the baud rate,
552				"p" is parity ("n", "o", or "e"), "n" is number of
553				bits, and "f" is flow control ("r" for RTS or
554				omit it).  Default is "9600n8".
555	
556				See Documentation/serial-console.txt for more
557				information.  See
558				Documentation/networking/netconsole.txt for an
559				alternative.
560	
561			uart[8250],io,<addr>[,options]
562			uart[8250],mmio,<addr>[,options]
563				Start an early, polled-mode console on the 8250/16550
564				UART at the specified I/O port or MMIO address,
565				switching to the matching ttyS device later.  The
566				options are the same as for ttyS, above.
567			hvc<n>	Use the hypervisor console device <n>. This is for
568				both Xen and PowerPC hypervisors.
569	
570	                If the device connected to the port is not a TTY but a braille
571	                device, prepend "brl," before the device type, for instance
572				console=brl,ttyS0
573			For now, only VisioBraille is supported.
574	
575		consoleblank=	[KNL] The console blank (screen saver) timeout in
576				seconds. Defaults to 10*60 = 10mins. A value of 0
577				disables the blank timer.
578	
579		coredump_filter=
580				[KNL] Change the default value for
581				/proc/<pid>/coredump_filter.
582				See also Documentation/filesystems/proc.txt.
583	
584		cpuidle.off=1	[CPU_IDLE]
585				disable the cpuidle sub-system
586	
587		cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
588				Format:
589				<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
590	
591		crashkernel=size[KMG][@offset[KMG]]
592				[KNL] Using kexec, Linux can switch to a 'crash kernel'
593				upon panic. This parameter reserves the physical
594				memory region [offset, offset + size] for that kernel
595				image. If '@offset' is omitted, then a suitable offset
596				is selected automatically. Check
597				Documentation/kdump/kdump.txt for further details.
598	
599		crashkernel=range1:size1[,range2:size2,...][@offset]
600				[KNL] Same as above, but depends on the memory
601				in the running system. The syntax of range is
602				start-[end] where start and end are both
603				a memory unit (amount[KMG]). See also
604				Documentation/kdump/kdump.txt for an example.
605	
606		crashkernel=size[KMG],high
607				[KNL, x86_64] range could be above 4G. Allow kernel
608				to allocate physical memory region from top, so could
609				be above 4G if system have more than 4G ram installed.
610				Otherwise memory region will be allocated below 4G, if
611				available.
612				It will be ignored if crashkernel=X is specified.
613		crashkernel=size[KMG],low
614				[KNL, x86_64] range under 4G. When crashkernel=X,high
615				is passed, kernel could allocate physical memory region
616				above 4G, that cause second kernel crash on system
617				that require some amount of low memory, e.g. swiotlb
618				requires at least 64M+32K low memory.  Kernel would
619				try to allocate 72M below 4G automatically.
620				This one let user to specify own low range under 4G
621				for second kernel instead.
622				0: to disable low allocation.
623				It will be ignored when crashkernel=X,high is not used
624				or memory reserved is below 4G.
625	
626		cs89x0_dma=	[HW,NET]
627				Format: <dma>
628	
629		cs89x0_media=	[HW,NET]
630				Format: { rj45 | aui | bnc }
631	
632		dasd=		[HW,NET]
633				See header of drivers/s390/block/dasd_devmap.c.
634	
635		db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
636				(one device per port)
637				Format: <port#>,<type>
638				See also Documentation/input/joystick-parport.txt
639	
640		ddebug_query=   [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
641				time. See Documentation/dynamic-debug-howto.txt for
642				details.  Deprecated, see dyndbg.
643	
644		debug		[KNL] Enable kernel debugging (events log level).
645	
646		debug_locks_verbose=
647				[KNL] verbose self-tests
648				Format=<0|1>
649				Print debugging info while doing the locking API
650				self-tests.
651				We default to 0 (no extra messages), setting it to
652				1 will print _a lot_ more information - normally
653				only useful to kernel developers.
654	
655		debug_objects	[KNL] Enable object debugging
656	
657		no_debug_objects
658				[KNL] Disable object debugging
659	
660		debug_guardpage_minorder=
661				[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
662				parameter allows control of the order of pages that will
663				be intentionally kept free (and hence protected) by the
664				buddy allocator. Bigger value increase the probability
665				of catching random memory corruption, but reduce the
666				amount of memory for normal system use. The maximum
667				possible value is MAX_ORDER/2.  Setting this parameter
668				to 1 or 2 should be enough to identify most random
669				memory corruption problems caused by bugs in kernel or
670				driver code when a CPU writes to (or reads from) a
671				random memory location. Note that there exists a class
672				of memory corruptions problems caused by buggy H/W or
673				F/W or by drivers badly programing DMA (basically when
674				memory is written at bus level and the CPU MMU is
675				bypassed) which are not detectable by
676				CONFIG_DEBUG_PAGEALLOC, hence this option will not help
677				tracking down these problems.
678	
679		debugpat	[X86] Enable PAT debugging
680	
681		decnet.addr=	[HW,NET]
682				Format: <area>[,<node>]
683				See also Documentation/networking/decnet.txt.
684	
685		default_hugepagesz=
686				[same as hugepagesz=] The size of the default
687				HugeTLB page size. This is the size represented by
688				the legacy /proc/ hugepages APIs, used for SHM, and
689				default size when mounting hugetlbfs filesystems.
690				Defaults to the default architecture's huge page size
691				if not specified.
692	
693		dhash_entries=	[KNL]
694				Set number of hash buckets for dentry cache.
695	
696		digi=		[HW,SERIAL]
697				IO parameters + enable/disable command.
698	
699		digiepca=	[HW,SERIAL]
700				See drivers/char/README.epca and
701				Documentation/serial/digiepca.txt.
702	
703		disable=	[IPV6]
704				See Documentation/networking/ipv6.txt.
705	
706		disable_ddw     [PPC/PSERIES]
707				Disable Dynamic DMA Window support. Use this if
708				to workaround buggy firmware.
709	
710		disable_ipv6=	[IPV6]
711				See Documentation/networking/ipv6.txt.
712	
713		disable_mtrr_cleanup [X86]
714				The kernel tries to adjust MTRR layout from continuous
715				to discrete, to make X server driver able to add WB
716				entry later. This parameter disables that.
717	
718		disable_mtrr_trim [X86, Intel and AMD only]
719				By default the kernel will trim any uncacheable
720				memory out of your available memory pool based on
721				MTRR settings.  This parameter disables that behavior,
722				possibly causing your machine to run very slowly.
723	
724		disable_timer_pin_1 [X86]
725				Disable PIN 1 of APIC timer
726				Can be useful to work around chipset bugs.
727	
728		dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
729				this option disables the debugging code at boot.
730	
731		dma_debug_entries=<number>
732				This option allows to tune the number of preallocated
733				entries for DMA-API debugging code. One entry is
734				required per DMA-API allocation. Use this if the
735				DMA-API debugging code disables itself because the
736				architectural default is too low.
737	
738		dma_debug_driver=<driver_name>
739				With this option the DMA-API debugging driver
740				filter feature can be enabled at boot time. Just
741				pass the driver to filter for as the parameter.
742				The filter can be disabled or changed to another
743				driver later using sysfs.
744	
745		drm_kms_helper.edid_firmware=[<connector>:]<file>
746				Broken monitors, graphic adapters and KVMs may
747				send no or incorrect EDID data sets. This parameter
748				allows to specify an EDID data set in the
749				/lib/firmware directory that is used instead.
750				Generic built-in EDID data sets are used, if one of
751				edid/1024x768.bin, edid/1280x1024.bin,
752				edid/1680x1050.bin, or edid/1920x1080.bin is given
753				and no file with the same name exists. Details and
754				instructions how to build your own EDID data are
755				available in Documentation/EDID/HOWTO.txt. An EDID
756				data set will only be used for a particular connector,
757				if its name and a colon are prepended to the EDID
758				name.
759	
760		dscc4.setup=	[NET]
761	
762		dyndbg[="val"]		[KNL,DYNAMIC_DEBUG]
763		module.dyndbg[="val"]
764				Enable debug messages at boot time.  See
765				Documentation/dynamic-debug-howto.txt for details.
766	
767		earlycon=	[KNL] Output early console device and options.
768			uart[8250],io,<addr>[,options]
769			uart[8250],mmio,<addr>[,options]
770			uart[8250],mmio32,<addr>[,options]
771				Start an early, polled-mode console on the 8250/16550
772				UART at the specified I/O port or MMIO address.
773				MMIO inter-register address stride is either 8-bit
774				(mmio) or 32-bit (mmio32).
775				The options are the same as for ttyS, above.
776	
777		earlyprintk=	[X86,SH,BLACKFIN]
778				earlyprintk=vga
779				earlyprintk=xen
780				earlyprintk=serial[,ttySn[,baudrate]]
781				earlyprintk=ttySn[,baudrate]
782				earlyprintk=dbgp[debugController#]
783	
784				Append ",keep" to not disable it when the real console
785				takes over.
786	
787				Only vga or serial or usb debug port at a time.
788	
789				Currently only ttyS0 and ttyS1 are supported.
790	
791				Interaction with the standard serial driver is not
792				very good.
793	
794				The VGA output is eventually overwritten by the real
795				console.
796	
797				The xen output can only be used by Xen PV guests.
798	
799		ekgdboc=	[X86,KGDB] Allow early kernel console debugging
800				ekgdboc=kbd
801	
802				This is designed to be used in conjunction with
803				the boot argument: earlyprintk=vga
804	
805		edd=		[EDD]
806				Format: {"off" | "on" | "skip[mbr]"}
807	
808		efi_no_storage_paranoia [EFI; X86]
809				Using this parameter you can use more than 50% of
810				your efi variable storage. Use this parameter only if
811				you are really sure that your UEFI does sane gc and
812				fulfills the spec otherwise your board may brick.
813	
814		eisa_irq_edge=	[PARISC,HW]
815				See header of drivers/parisc/eisa.c.
816	
817		elanfreq=	[X86-32]
818				See comment before function elanfreq_setup() in
819				arch/x86/kernel/cpu/cpufreq/elanfreq.c.
820	
821		elevator=	[IOSCHED]
822				Format: {"cfq" | "deadline" | "noop"}
823				See Documentation/block/cfq-iosched.txt and
824				Documentation/block/deadline-iosched.txt for details.
825	
826		elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
827				Specifies physical address of start of kernel core
828				image elf header and optionally the size. Generally
829				kexec loader will pass this option to capture kernel.
830				See Documentation/kdump/kdump.txt for details.
831	
832		enable_mtrr_cleanup [X86]
833				The kernel tries to adjust MTRR layout from continuous
834				to discrete, to make X server driver able to add WB
835				entry later. This parameter enables that.
836	
837		enable_timer_pin_1 [X86]
838				Enable PIN 1 of APIC timer
839				Can be useful to work around chipset bugs
840				(in particular on some ATI chipsets).
841				The kernel tries to set a reasonable default.
842	
843		enforcing	[SELINUX] Set initial enforcing status.
844				Format: {"0" | "1"}
845				See security/selinux/Kconfig help text.
846				0 -- permissive (log only, no denials).
847				1 -- enforcing (deny and log).
848				Default value is 0.
849				Value can be changed at runtime via /selinux/enforce.
850	
851		erst_disable	[ACPI]
852				Disable Error Record Serialization Table (ERST)
853				support.
854	
855		ether=		[HW,NET] Ethernet cards parameters
856				This option is obsoleted by the "netdev=" option, which
857				has equivalent usage. See its documentation for details.
858	
859		evm=		[EVM]
860				Format: { "fix" }
861				Permit 'security.evm' to be updated regardless of
862				current integrity status.
863	
864		failslab=
865		fail_page_alloc=
866		fail_make_request=[KNL]
867				General fault injection mechanism.
868				Format: <interval>,<probability>,<space>,<times>
869				See also Documentation/fault-injection/.
870	
871		floppy=		[HW]
872				See Documentation/blockdev/floppy.txt.
873	
874		force_pal_cache_flush
875				[IA-64] Avoid check_sal_cache_flush which may hang on
876				buggy SAL_CACHE_FLUSH implementations. Using this
877				parameter will force ia64_sal_cache_flush to call
878				ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
879	
880		ftrace=[tracer]
881				[FTRACE] will set and start the specified tracer
882				as early as possible in order to facilitate early
883				boot debugging.
884	
885		ftrace_dump_on_oops[=orig_cpu]
886				[FTRACE] will dump the trace buffers on oops.
887				If no parameter is passed, ftrace will dump
888				buffers of all CPUs, but if you pass orig_cpu, it will
889				dump only the buffer of the CPU that triggered the
890				oops.
891	
892		ftrace_filter=[function-list]
893				[FTRACE] Limit the functions traced by the function
894				tracer at boot up. function-list is a comma separated
895				list of functions. This list can be changed at run
896				time by the set_ftrace_filter file in the debugfs
897				tracing directory.
898	
899		ftrace_notrace=[function-list]
900				[FTRACE] Do not trace the functions specified in
901				function-list. This list can be changed at run time
902				by the set_ftrace_notrace file in the debugfs
903				tracing directory.
904	
905		ftrace_graph_filter=[function-list]
906				[FTRACE] Limit the top level callers functions traced
907				by the function graph tracer at boot up.
908				function-list is a comma separated list of functions
909				that can be changed at run time by the
910				set_graph_function file in the debugfs tracing directory.
911	
912		gamecon.map[2|3]=
913				[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
914				support via parallel port (up to 5 devices per port)
915				Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
916				See also Documentation/input/joystick-parport.txt
917	
918		gamma=		[HW,DRM]
919	
920		gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
921				Format: off | on
922				default: on
923	
924		gcov_persist=	[GCOV] When non-zero (default), profiling data for
925				kernel modules is saved and remains accessible via
926				debugfs, even when the module is unloaded/reloaded.
927				When zero, profiling data is discarded and associated
928				debugfs files are removed at module unload time.
929	
930		gpt		[EFI] Forces disk with valid GPT signature but
931				invalid Protective MBR to be treated as GPT.
932	
933		grcan.enable0=	[HW] Configuration of physical interface 0. Determines
934				the "Enable 0" bit of the configuration register.
935				Format: 0 | 1
936				Default: 0
937		grcan.enable1=	[HW] Configuration of physical interface 1. Determines
938				the "Enable 0" bit of the configuration register.
939				Format: 0 | 1
940				Default: 0
941		grcan.select=	[HW] Select which physical interface to use.
942				Format: 0 | 1
943				Default: 0
944		grcan.txsize=	[HW] Sets the size of the tx buffer.
945				Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
946				Default: 1024
947		grcan.rxsize=	[HW] Sets the size of the rx buffer.
948				Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
949				Default: 1024
950	
951		hashdist=	[KNL,NUMA] Large hashes allocated during boot
952				are distributed across NUMA nodes.  Defaults on
953				for 64-bit NUMA, off otherwise.
954				Format: 0 | 1 (for off | on)
955	
956		hcl=		[IA-64] SGI's Hardware Graph compatibility layer
957	
958		hd=		[EIDE] (E)IDE hard drive subsystem geometry
959				Format: <cyl>,<head>,<sect>
960	
961		hest_disable	[ACPI]
962				Disable Hardware Error Source Table (HEST) support;
963				corresponding firmware-first mode error processing
964				logic will be disabled.
965	
966		highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
967				size of <nn>. This works even on boxes that have no
968				highmem otherwise. This also works to reduce highmem
969				size on bigger boxes.
970	
971		highres=	[KNL] Enable/disable high resolution timer mode.
972				Valid parameters: "on", "off"
973				Default: "on"
974	
975		hisax=		[HW,ISDN]
976				See Documentation/isdn/README.HiSax.
977	
978		hlt		[BUGS=ARM,SH]
979	
980		hpet=		[X86-32,HPET] option to control HPET usage
981				Format: { enable (default) | disable | force |
982					verbose }
983				disable: disable HPET and use PIT instead
984				force: allow force enabled of undocumented chips (ICH4,
985					VIA, nVidia)
986				verbose: show contents of HPET registers during setup
987	
988		hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
989		hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
990				On x86-64 and powerpc, this option can be specified
991				multiple times interleaved with hugepages= to reserve
992				huge pages of different sizes. Valid pages sizes on
993				x86-64 are 2M (when the CPU supports "pse") and 1G
994				(when the CPU supports the "pdpe1gb" cpuinfo flag)
995				Note that 1GB pages can only be allocated at boot time
996				using hugepages= and not freed afterwards.
997	
998		hvc_iucv=	[S390] Number of z/VM IUCV hypervisor console (HVC)
999				       terminal devices. Valid values: 0..8
1000		hvc_iucv_allow=	[S390] Comma-separated list of z/VM user IDs.
1001				       If specified, z/VM IUCV HVC accepts connections
1002				       from listed z/VM user IDs only.
1003	
1004		hwthread_map=	[METAG] Comma-separated list of Linux cpu id to
1005				        hardware thread id mappings.
1006					Format: <cpu>:<hwthread>
1007	
1008		keep_bootcon	[KNL]
1009				Do not unregister boot console at start. This is only
1010				useful for debugging when something happens in the window
1011				between unregistering the boot console and initializing
1012				the real console.
1013	
1014		i2c_bus=	[HW] Override the default board specific I2C bus speed
1015				     or register an additional I2C bus that is not
1016				     registered from board initialization code.
1017				     Format:
1018				     <bus_id>,<clkrate>
1019	
1020		i8042.debug	[HW] Toggle i8042 debug mode
1021		i8042.direct	[HW] Put keyboard port into non-translated mode
1022		i8042.dumbkbd	[HW] Pretend that controller can only read data from
1023				     keyboard and cannot control its state
1024				     (Don't attempt to blink the leds)
1025		i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
1026		i8042.nokbd	[HW] Don't check/create keyboard port
1027		i8042.noloop	[HW] Disable the AUX Loopback command while probing
1028				     for the AUX port
1029		i8042.nomux	[HW] Don't check presence of an active multiplexing
1030				     controller
1031		i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1032				     controllers
1033		i8042.notimeout	[HW] Ignore timeout condition signalled by controller
1034		i8042.reset	[HW] Reset the controller during init and cleanup
1035		i8042.unlock	[HW] Unlock (ignore) the keylock
1036	
1037		i810=		[HW,DRM]
1038	
1039		i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
1040				indicates that the driver is running on unsupported
1041				hardware.
1042		i8k.force	[HW] Activate i8k driver even if SMM BIOS signature
1043				does not match list of supported models.
1044		i8k.power_status
1045				[HW] Report power status in /proc/i8k
1046				(disabled by default)
1047		i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN
1048				capability is set.
1049	
1050		i915.invert_brightness=
1051				[DRM] Invert the sense of the variable that is used to
1052				set the brightness of the panel backlight. Normally a
1053				brightness value of 0 indicates backlight switched off,
1054				and the maximum of the brightness value sets the backlight
1055				to maximum brightness. If this parameter is set to 0
1056				(default) and the machine requires it, or this parameter
1057				is set to 1, a brightness value of 0 sets the backlight
1058				to maximum brightness, and the maximum of the brightness
1059				value switches the backlight off.
1060				-1 -- never invert brightness
1061				 0 -- machine default
1062				 1 -- force brightness inversion
1063	
1064		icn=		[HW,ISDN]
1065				Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1066	
1067		ide-core.nodma=	[HW] (E)IDE subsystem
1068				Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1069				.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1070				.cdrom .chs .ignore_cable are additional options
1071				See Documentation/ide/ide.txt.
1072	
1073		ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1074				Claim all unknown PCI IDE storage controllers.
1075	
1076		idle=		[X86]
1077				Format: idle=poll, idle=halt, idle=nomwait
1078				Poll forces a polling idle loop that can slightly
1079				improve the performance of waking up a idle CPU, but
1080				will use a lot of power and make the system run hot.
1081				Not recommended.
1082				idle=halt: Halt is forced to be used for CPU idle.
1083				In such case C2/C3 won't be used again.
1084				idle=nomwait: Disable mwait for CPU C-states
1085	
1086		ignore_loglevel	[KNL]
1087				Ignore loglevel setting - this will print /all/
1088				kernel messages to the console. Useful for debugging.
1089				We also add it as printk module parameter, so users
1090				could change it dynamically, usually by
1091				/sys/module/printk/parameters/ignore_loglevel.
1092	
1093		ihash_entries=	[KNL]
1094				Set number of hash buckets for inode cache.
1095	
1096		ima_appraise=	[IMA] appraise integrity measurements
1097				Format: { "off" | "enforce" | "fix" }
1098				default: "enforce"
1099	
1100		ima_appraise_tcb [IMA]
1101				The builtin appraise policy appraises all files
1102				owned by uid=0.
1103	
1104		ima_audit=	[IMA]
1105				Format: { "0" | "1" }
1106				0 -- integrity auditing messages. (Default)
1107				1 -- enable informational integrity auditing messages.
1108	
1109		ima_hash=	[IMA]
1110				Format: { "sha1" | "md5" }
1111				default: "sha1"
1112	
1113		ima_tcb		[IMA]
1114				Load a policy which meets the needs of the Trusted
1115				Computing Base.  This means IMA will measure all
1116				programs exec'd, files mmap'd for exec, and all files
1117				opened for read by uid=0.
1118	
1119		init=		[KNL]
1120				Format: <full_path>
1121				Run specified binary instead of /sbin/init as init
1122				process.
1123	
1124		initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
1125				for working out where the kernel is dying during
1126				startup.
1127	
1128		initrd=		[BOOT] Specify the location of the initial ramdisk
1129	
1130		inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
1131				Format: <irq>
1132	
1133		intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
1134			on
1135				Enable intel iommu driver.
1136			off
1137				Disable intel iommu driver.
1138			igfx_off [Default Off]
1139				By default, gfx is mapped as normal device. If a gfx
1140				device has a dedicated DMAR unit, the DMAR unit is
1141				bypassed by not enabling DMAR with this option. In
1142				this case, gfx device will use physical address for
1143				DMA.
1144			forcedac [x86_64]
1145				With this option iommu will not optimize to look
1146				for io virtual address below 32-bit forcing dual
1147				address cycle on pci bus for cards supporting greater
1148				than 32-bit addressing. The default is to look
1149				for translation below 32-bit and if not available
1150				then look in the higher range.
1151			strict [Default Off]
1152				With this option on every unmap_single operation will
1153				result in a hardware IOTLB flush operation as opposed
1154				to batching them for performance.
1155			sp_off [Default Off]
1156				By default, super page will be supported if Intel IOMMU
1157				has the capability. With this option, super page will
1158				not be supported.
1159	
1160		intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
1161				0	disables intel_idle and fall back on acpi_idle.
1162				1 to 6	specify maximum depth of C-state.
1163	
1164		intel_pstate=  [X86]
1165			       disable
1166			         Do not enable intel_pstate as the default
1167			         scaling driver for the supported processors
1168	
1169		intremap=	[X86-64, Intel-IOMMU]
1170				on	enable Interrupt Remapping (default)
1171				off	disable Interrupt Remapping
1172				nosid	disable Source ID checking
1173				no_x2apic_optout
1174					BIOS x2APIC opt-out request will be ignored
1175	
1176		iomem=		Disable strict checking of access to MMIO memory
1177			strict	regions from userspace.
1178			relaxed
1179	
1180		iommu=		[x86]
1181			off
1182			force
1183			noforce
1184			biomerge
1185			panic
1186			nopanic
1187			merge
1188			nomerge
1189			forcesac
1190			soft
1191			pt		[x86, IA-64]
1192	
1193	
1194		io7=		[HW] IO7 for Marvel based alpha systems
1195				See comment before marvel_specify_io7 in
1196				arch/alpha/kernel/core_marvel.c.
1197	
1198		io_delay=	[X86] I/O delay method
1199			0x80
1200				Standard port 0x80 based delay
1201			0xed
1202				Alternate port 0xed based delay (needed on some systems)
1203			udelay
1204				Simple two microseconds delay
1205			none
1206				No delay
1207	
1208		ip=		[IP_PNP]
1209				See Documentation/filesystems/nfs/nfsroot.txt.
1210	
1211		ip2=		[HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1212				See comment before ip2_setup() in
1213				drivers/char/ip2/ip2base.c.
1214	
1215		irqfixup	[HW]
1216				When an interrupt is not handled search all handlers
1217				for it. Intended to get systems with badly broken
1218				firmware running.
1219	
1220		irqpoll		[HW]
1221				When an interrupt is not handled search all handlers
1222				for it. Also check all handlers each timer
1223				interrupt. Intended to get systems with badly broken
1224				firmware running.
1225	
1226		isapnp=		[ISAPNP]
1227				Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1228	
1229		isolcpus=	[KNL,SMP] Isolate CPUs from the general scheduler.
1230				Format:
1231				<cpu number>,...,<cpu number>
1232				or
1233				<cpu number>-<cpu number>
1234				(must be a positive range in ascending order)
1235				or a mixture
1236				<cpu number>,...,<cpu number>-<cpu number>
1237	
1238				This option can be used to specify one or more CPUs
1239				to isolate from the general SMP balancing and scheduling
1240				algorithms. You can move a process onto or off an
1241				"isolated" CPU via the CPU affinity syscalls or cpuset.
1242				<cpu number> begins at 0 and the maximum value is
1243				"number of CPUs in system - 1".
1244	
1245				This option is the preferred way to isolate CPUs. The
1246				alternative -- manually setting the CPU mask of all
1247				tasks in the system -- can cause problems and
1248				suboptimal load balancer performance.
1249	
1250		iucv=		[HW,NET]
1251	
1252		js=		[HW,JOY] Analog joystick
1253				See Documentation/input/joystick.txt.
1254	
1255		keepinitrd	[HW,ARM]
1256	
1257		kernelcore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
1258				specifies the amount of memory usable by the kernel
1259				for non-movable allocations.  The requested amount is
1260				spread evenly throughout all nodes in the system. The
1261				remaining memory in each node is used for Movable
1262				pages. In the event, a node is too small to have both
1263				kernelcore and Movable pages, kernelcore pages will
1264				take priority and other nodes will have a larger number
1265				of kernelcore pages.  The Movable zone is used for the
1266				allocation of pages that may be reclaimed or moved
1267				by the page migration subsystem.  This means that
1268				HugeTLB pages may not be allocated from this zone.
1269				Note that allocations like PTEs-from-HighMem still
1270				use the HighMem zone if it exists, and the Normal
1271				zone if it does not.
1272	
1273		kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
1274				Format: <Controller#>[,poll interval]
1275				The controller # is the number of the ehci usb debug
1276				port as it is probed via PCI.  The poll interval is
1277				optional and is the number seconds in between
1278				each poll cycle to the debug port in case you need
1279				the functionality for interrupting the kernel with
1280				gdb or control-c on the dbgp connection.  When
1281				not using this parameter you use sysrq-g to break into
1282				the kernel debugger.
1283	
1284		kgdboc=		[KGDB,HW] kgdb over consoles.
1285				Requires a tty driver that supports console polling,
1286				or a supported polling keyboard driver (non-usb).
1287				 Serial only format: <serial_device>[,baud]
1288				 keyboard only format: kbd
1289				 keyboard and serial format: kbd,<serial_device>[,baud]
1290				Optional Kernel mode setting:
1291				 kms, kbd format: kms,kbd
1292				 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1293	
1294		kgdbwait	[KGDB] Stop kernel execution and enter the
1295				kernel debugger at the earliest opportunity.
1296	
1297		kmac=		[MIPS] korina ethernet MAC address.
1298				Configure the RouterBoard 532 series on-chip
1299				Ethernet adapter MAC address.
1300	
1301		kmemleak=	[KNL] Boot-time kmemleak enable/disable
1302				Valid arguments: on, off
1303				Default: on
1304	
1305		kstack=N	[X86] Print N words from the kernel stack
1306				in oops dumps.
1307	
1308		kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1309				Default is 0 (don't ignore, but inject #GP)
1310	
1311		kvm.mmu_audit=	[KVM] This is a R/W parameter which allows audit
1312				KVM MMU at runtime.
1313				Default is 0 (off)
1314	
1315		kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.
1316				Default is 1 (enabled)
1317	
1318		kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)
1319				for all guests.
1320				Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1321	
1322		kvm-intel.ept=	[KVM,Intel] Disable extended page tables
1323				(virtualized MMU) support on capable Intel chips.
1324				Default is 1 (enabled)
1325	
1326		kvm-intel.emulate_invalid_guest_state=
1327				[KVM,Intel] Enable emulation of invalid guest states
1328				Default is 0 (disabled)
1329	
1330		kvm-intel.flexpriority=
1331				[KVM,Intel] Disable FlexPriority feature (TPR shadow).
1332				Default is 1 (enabled)
1333	
1334		kvm-intel.nested=
1335				[KVM,Intel] Enable VMX nesting (nVMX).
1336				Default is 0 (disabled)
1337	
1338		kvm-intel.unrestricted_guest=
1339				[KVM,Intel] Disable unrestricted guest feature
1340				(virtualized real and unpaged mode) on capable
1341				Intel chips. Default is 1 (enabled)
1342	
1343		kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification
1344				feature (tagged TLBs) on capable Intel chips.
1345				Default is 1 (enabled)
1346	
1347		l2cr=		[PPC]
1348	
1349		l3cr=		[PPC]
1350	
1351		lapic		[X86-32,APIC] Enable the local APIC even if BIOS
1352				disabled it.
1353	
1354		lapic=		[x86,APIC] "notscdeadline" Do not use TSC deadline
1355				value for LAPIC timer one-shot implementation. Default
1356				back to the programmable timer unit in the LAPIC.
1357	
1358		lapic_timer_c2_ok	[X86,APIC] trust the local apic timer
1359				in C2 power state.
1360	
1361		libata.dma=	[LIBATA] DMA control
1362				libata.dma=0	  Disable all PATA and SATA DMA
1363				libata.dma=1	  PATA and SATA Disk DMA only
1364				libata.dma=2	  ATAPI (CDROM) DMA only
1365				libata.dma=4	  Compact Flash DMA only
1366				Combinations also work, so libata.dma=3 enables DMA
1367				for disks and CDROMs, but not CFs.
1368	
1369		libata.ignore_hpa=	[LIBATA] Ignore HPA limit
1370				libata.ignore_hpa=0	  keep BIOS limits (default)
1371				libata.ignore_hpa=1	  ignore limits, using full disk
1372	
1373		libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
1374				when set.
1375				Format: <int>
1376	
1377		libata.force=	[LIBATA] Force configurations.  The format is comma
1378				separated list of "[ID:]VAL" where ID is
1379				PORT[.DEVICE].  PORT and DEVICE are decimal numbers
1380				matching port, link or device.  Basically, it matches
1381				the ATA ID string printed on console by libata.  If
1382				the whole ID part is omitted, the last PORT and DEVICE
1383				values are used.  If ID hasn't been specified yet, the
1384				configuration applies to all ports, links and devices.
1385	
1386				If only DEVICE is omitted, the parameter applies to
1387				the port and all links and devices behind it.  DEVICE
1388				number of 0 either selects the first device or the
1389				first fan-out link behind PMP device.  It does not
1390				select the host link.  DEVICE number of 15 selects the
1391				host link and device attached to it.
1392	
1393				The VAL specifies the configuration to force.  As long
1394				as there's no ambiguity shortcut notation is allowed.
1395				For example, both 1.5 and 1.5G would work for 1.5Gbps.
1396				The following configurations can be forced.
1397	
1398				* Cable type: 40c, 80c, short40c, unk, ign or sata.
1399				  Any ID with matching PORT is used.
1400	
1401				* SATA link speed limit: 1.5Gbps or 3.0Gbps.
1402	
1403				* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1404				  udma[/][16,25,33,44,66,100,133] notation is also
1405				  allowed.
1406	
1407				* [no]ncq: Turn on or off NCQ.
1408	
1409				* nohrst, nosrst, norst: suppress hard, soft
1410	                          and both resets.
1411	
1412				* rstonce: only attempt one reset during
1413				  hot-unplug link recovery
1414	
1415				* dump_id: dump IDENTIFY data.
1416	
1417				If there are multiple matching configurations changing
1418				the same attribute, the last one is used.
1419	
1420		memblock=debug	[KNL] Enable memblock debug messages.
1421	
1422		load_ramdisk=	[RAM] List of ramdisks to load from floppy
1423				See Documentation/blockdev/ramdisk.txt.
1424	
1425		lockd.nlm_grace_period=P  [NFS] Assign grace period.
1426				Format: <integer>
1427	
1428		lockd.nlm_tcpport=N	[NFS] Assign TCP port.
1429				Format: <integer>
1430	
1431		lockd.nlm_timeout=T	[NFS] Assign timeout value.
1432				Format: <integer>
1433	
1434		lockd.nlm_udpport=M	[NFS] Assign UDP port.
1435				Format: <integer>
1436	
1437		logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
1438				Format: <irq>
1439	
1440		loglevel=	All Kernel Messages with a loglevel smaller than the
1441				console loglevel will be printed to the console. It can
1442				also be changed with klogd or other programs. The
1443				loglevels are defined as follows:
1444	
1445				0 (KERN_EMERG)		system is unusable
1446				1 (KERN_ALERT)		action must be taken immediately
1447				2 (KERN_CRIT)		critical conditions
1448				3 (KERN_ERR)		error conditions
1449				4 (KERN_WARNING)	warning conditions
1450				5 (KERN_NOTICE)		normal but significant condition
1451				6 (KERN_INFO)		informational
1452				7 (KERN_DEBUG)		debug-level messages
1453	
1454		log_buf_len=n[KMG]	Sets the size of the printk ring buffer,
1455				in bytes.  n must be a power of two.  The default
1456				size is set in the kernel config file.
1457	
1458		logo.nologo	[FB] Disables display of the built-in Linux logo.
1459				This may be used to provide more screen space for
1460				kernel log messages and is useful when debugging
1461				kernel boot problems.
1462	
1463		lp=0		[LP]	Specify parallel ports to use, e.g,
1464		lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
1465		lp=reset		first parallel port). 'lp=0' disables the
1466		lp=auto			printer driver. 'lp=reset' (which can be
1467					specified in addition to the ports) causes
1468					attached printers to be reset. Using
1469					lp=port1,port2,... specifies the parallel ports
1470					to associate lp devices with, starting with
1471					lp0. A port specification may be 'none' to skip
1472					that lp device, or a parport name such as
1473					'parport0'. Specifying 'lp=auto' instead of a
1474					port specification list means that device IDs
1475					from each port should be examined, to see if
1476					an IEEE 1284-compliant printer is attached; if
1477					so, the driver will manage that printer.
1478					See also header of drivers/char/lp.c.
1479	
1480		lpj=n		[KNL]
1481				Sets loops_per_jiffy to given constant, thus avoiding
1482				time-consuming boot-time autodetection (up to 250 ms per
1483				CPU). 0 enables autodetection (default). To determine
1484				the correct value for your kernel, boot with normal
1485				autodetection and see what value is printed. Note that
1486				on SMP systems the preset will be applied to all CPUs,
1487				which is likely to cause problems if your CPUs need
1488				significantly divergent settings. An incorrect value
1489				will cause delays in the kernel to be wrong, leading to
1490				unpredictable I/O errors and other breakage. Although
1491				unlikely, in the extreme case this might damage your
1492				hardware.
1493	
1494		ltpc=		[NET]
1495				Format: <io>,<irq>,<dma>
1496	
1497		machvec=	[IA-64] Force the use of a particular machine-vector
1498				(machvec) in a generic kernel.
1499				Example: machvec=hpzx1_swiotlb
1500	
1501		machtype=	[Loongson] Share the same kernel image file between different
1502				 yeeloong laptop.
1503				Example: machtype=lemote-yeeloong-2f-7inch
1504	
1505		max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater
1506				than or equal to this physical address is ignored.
1507	
1508		maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
1509				should make use of.  maxcpus=n : n >= 0 limits the
1510				kernel to using 'n' processors.  n=0 is a special case,
1511				it is equivalent to "nosmp", which also disables
1512				the IO APIC.
1513	
1514		max_loop=	[LOOP] The number of loop block devices that get
1515		(loop.max_loop)	unconditionally pre-created at init time. The default
1516				number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1517				of statically allocating a predefined number, loop
1518				devices can be requested on-demand with the
1519				/dev/loop-control interface.
1520	
1521		mce		[X86-32] Machine Check Exception
1522	
1523		mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.txt
1524	
1525		md=		[HW] RAID subsystems devices and level
1526				See Documentation/md.txt.
1527	
1528		mdacon=		[MDA]
1529				Format: <first>,<last>
1530				Specifies range of consoles to be captured by the MDA.
1531	
1532		mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
1533				Amount of memory to be used when the kernel is not able
1534				to see the whole system memory or for test.
1535				[X86] Work as limiting max address. Use together
1536				with memmap= to avoid physical address space collisions.
1537				Without memmap= PCI devices could be placed at addresses
1538				belonging to unused RAM.
1539	
1540		mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
1541				memory.
1542	
1543		memchunk=nn[KMG]
1544				[KNL,SH] Allow user to override the default size for
1545				per-device physically contiguous DMA buffers.
1546	
1547		memmap=exactmap	[KNL,X86] Enable setting of an exact
1548				E820 memory map, as specified by the user.
1549				Such memmap=exactmap lines can be constructed based on
1550				BIOS output or other requirements. See the memmap=nn@ss
1551				option description.
1552	
1553		memmap=nn[KMG]@ss[KMG]
1554				[KNL] Force usage of a specific region of memory
1555				Region of memory to be used, from ss to ss+nn.
1556	
1557		memmap=nn[KMG]#ss[KMG]
1558				[KNL,ACPI] Mark specific memory as ACPI data.
1559				Region of memory to be used, from ss to ss+nn.
1560	
1561		memmap=nn[KMG]$ss[KMG]
1562				[KNL,ACPI] Mark specific memory as reserved.
1563				Region of memory to be used, from ss to ss+nn.
1564				Example: Exclude memory from 0x18690000-0x1869ffff
1565				         memmap=64K$0x18690000
1566				         or
1567				         memmap=0x10000$0x18690000
1568	
1569		memory_corruption_check=0/1 [X86]
1570				Some BIOSes seem to corrupt the first 64k of
1571				memory when doing things like suspend/resume.
1572				Setting this option will scan the memory
1573				looking for corruption.  Enabling this will
1574				both detect corruption and prevent the kernel
1575				from using the memory being corrupted.
1576				However, its intended as a diagnostic tool; if
1577				repeatable BIOS-originated corruption always
1578				affects the same memory, you can use memmap=
1579				to prevent the kernel from using that memory.
1580	
1581		memory_corruption_check_size=size [X86]
1582				By default it checks for corruption in the low
1583				64k, making this memory unavailable for normal
1584				use.  Use this parameter to scan for
1585				corruption in more or less memory.
1586	
1587		memory_corruption_check_period=seconds [X86]
1588				By default it checks for corruption every 60
1589				seconds.  Use this parameter to check at some
1590				other rate.  0 disables periodic checking.
1591	
1592		memtest=	[KNL,X86] Enable memtest
1593				Format: <integer>
1594				default : 0 <disable>
1595				Specifies the number of memtest passes to be
1596				performed. Each pass selects another test
1597				pattern from a given set of patterns. Memtest
1598				fills the memory with this pattern, validates
1599				memory contents and reserves bad memory
1600				regions that are detected.
1601	
1602		meye.*=		[HW] Set MotionEye Camera parameters
1603				See Documentation/video4linux/meye.txt.
1604	
1605		mfgpt_irq=	[IA-32] Specify the IRQ to use for the
1606				Multi-Function General Purpose Timers on AMD Geode
1607				platforms.
1608	
1609		mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
1610				the BIOS has incorrectly applied a workaround. TinyBIOS
1611				version 0.98 is known to be affected, 0.99 fixes the
1612				problem by letting the user disable the workaround.
1613	
1614		mga=		[HW,DRM]
1615	
1616		min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this
1617				physical address is ignored.
1618	
1619		mini2440=	[ARM,HW,KNL]
1620				Format:[0..2][b][c][t]
1621				Default: "0tb"
1622				MINI2440 configuration specification:
1623				0 - The attached screen is the 3.5" TFT
1624				1 - The attached screen is the 7" TFT
1625				2 - The VGA Shield is attached (1024x768)
1626				Leaving out the screen size parameter will not load
1627				the TFT driver, and the framebuffer will be left
1628				unconfigured.
1629				b - Enable backlight. The TFT backlight pin will be
1630				linked to the kernel VESA blanking code and a GPIO
1631				LED. This parameter is not necessary when using the
1632				VGA shield.
1633				c - Enable the s3c camera interface.
1634				t - Reserved for enabling touchscreen support. The
1635				touchscreen support is not enabled in the mainstream
1636				kernel as of 2.6.30, a preliminary port can be found
1637				in the "bleeding edge" mini2440 support kernel at
1638				http://repo.or.cz/w/linux-2.6/mini2440.git
1639	
1640		mminit_loglevel=
1641				[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1642				parameter allows control of the logging verbosity for
1643				the additional memory initialisation checks. A value
1644				of 0 disables mminit logging and a level of 4 will
1645				log everything. Information is printed at KERN_DEBUG
1646				so loglevel=8 may also need to be specified.
1647	
1648		module.sig_enforce
1649				[KNL] When CONFIG_MODULE_SIG is set, this means that
1650				modules without (valid) signatures will fail to load.
1651				Note that if CONFIG_MODULE_SIG_ENFORCE is set, that
1652				is always true, so this option does nothing.
1653	
1654		mousedev.tap_time=
1655				[MOUSE] Maximum time between finger touching and
1656				leaving touchpad surface for touch to be considered
1657				a tap and be reported as a left button click (for
1658				touchpads working in absolute mode only).
1659				Format: <msecs>
1660		mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
1661				reporting absolute coordinates, such as tablets
1662		mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
1663				reporting absolute coordinates, such as tablets
1664	
1665		movablecore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
1666				is similar to kernelcore except it specifies the
1667				amount of memory used for migratable allocations.
1668				If both kernelcore and movablecore is specified,
1669				then kernelcore will be at *least* the specified
1670				value but may be more. If movablecore on its own
1671				is specified, the administrator must be careful
1672				that the amount of memory usable for all allocations
1673				is not too small.
1674	
1675		MTD_Partition=	[MTD]
1676				Format: <name>,<region-number>,<size>,<offset>
1677	
1678		MTD_Region=	[MTD] Format:
1679				<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1680	
1681		mtdparts=	[MTD]
1682				See drivers/mtd/cmdlinepart.c.
1683	
1684		multitce=off	[PPC]  This parameter disables the use of the pSeries
1685				firmware feature for updating multiple TCE entries
1686				at a time.
1687	
1688		onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
1689	
1690				Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1691	
1692				boundary - index of last SLC block on Flex-OneNAND.
1693					   The remaining blocks are configured as MLC blocks.
1694				lock	 - Configure if Flex-OneNAND boundary should be locked.
1695					   Once locked, the boundary cannot be changed.
1696					   1 indicates lock status, 0 indicates unlock status.
1697	
1698		mtdset=		[ARM]
1699				ARM/S3C2412 JIVE boot control
1700	
1701				See arch/arm/mach-s3c2412/mach-jive.c
1702	
1703		mtouchusb.raw_coordinates=
1704				[HW] Make the MicroTouch USB driver use raw coordinates
1705				('y', default) or cooked coordinates ('n')
1706	
1707		mtrr_chunk_size=nn[KMG] [X86]
1708				used for mtrr cleanup. It is largest continuous chunk
1709				that could hold holes aka. UC entries.
1710	
1711		mtrr_gran_size=nn[KMG] [X86]
1712				Used for mtrr cleanup. It is granularity of mtrr block.
1713				Default is 1.
1714				Large value could prevent small alignment from
1715				using up MTRRs.
1716	
1717		mtrr_spare_reg_nr=n [X86]
1718				Format: <integer>
1719				Range: 0,7 : spare reg number
1720				Default : 1
1721				Used for mtrr cleanup. It is spare mtrr entries number.
1722				Set to 2 or more if your graphical card needs more.
1723	
1724		n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card
1725	
1726		netdev=		[NET] Network devices parameters
1727				Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1728				Note that mem_start is often overloaded to mean
1729				something different and driver-specific.
1730				This usage is only documented in each driver source
1731				file if at all.
1732	
1733		nf_conntrack.acct=
1734				[NETFILTER] Enable connection tracking flow accounting
1735				0 to disable accounting
1736				1 to enable accounting
1737				Default value is 0.
1738	
1739		nfsaddrs=	[NFS] Deprecated.  Use ip= instead.
1740				See Documentation/filesystems/nfs/nfsroot.txt.
1741	
1742		nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
1743				See Documentation/filesystems/nfs/nfsroot.txt.
1744	
1745		nfsrootdebug	[NFS] enable nfsroot debugging messages.
1746				See Documentation/filesystems/nfs/nfsroot.txt.
1747	
1748		nfs.callback_tcpport=
1749				[NFS] set the TCP port on which the NFSv4 callback
1750				channel should listen.
1751	
1752		nfs.cache_getent=
1753				[NFS] sets the pathname to the program which is used
1754				to update the NFS client cache entries.
1755	
1756		nfs.cache_getent_timeout=
1757				[NFS] sets the timeout after which an attempt to
1758				update a cache entry is deemed to have failed.
1759	
1760		nfs.idmap_cache_timeout=
1761				[NFS] set the maximum lifetime for idmapper cache
1762				entries.
1763	
1764		nfs.enable_ino64=
1765				[NFS] enable 64-bit inode numbers.
1766				If zero, the NFS client will fake up a 32-bit inode
1767				number for the readdir() and stat() syscalls instead
1768				of returning the full 64-bit number.
1769				The default is to return 64-bit inode numbers.
1770	
1771		nfs.max_session_slots=
1772				[NFSv4.1] Sets the maximum number of session slots
1773				the client will attempt to negotiate with the server.
1774				This limits the number of simultaneous RPC requests
1775				that the client can send to the NFSv4.1 server.
1776				Note that there is little point in setting this
1777				value higher than the max_tcp_slot_table_limit.
1778	
1779		nfs.nfs4_disable_idmapping=
1780				[NFSv4] When set to the default of '1', this option
1781				ensures that both the RPC level authentication
1782				scheme and the NFS level operations agree to use
1783				numeric uids/gids if the mount is using the
1784				'sec=sys' security flavour. In effect it is
1785				disabling idmapping, which can make migration from
1786				legacy NFSv2/v3 systems to NFSv4 easier.
1787				Servers that do not support this mode of operation
1788				will be autodetected by the client, and it will fall
1789				back to using the idmapper.
1790				To turn off this behaviour, set the value to '0'.
1791		nfs.nfs4_unique_id=
1792				[NFS4] Specify an additional fixed unique ident-
1793				ification string that NFSv4 clients can insert into
1794				their nfs_client_id4 string.  This is typically a
1795				UUID that is generated at system install time.
1796	
1797		nfs.send_implementation_id =
1798				[NFSv4.1] Send client implementation identification
1799				information in exchange_id requests.
1800				If zero, no implementation identification information
1801				will be sent.
1802				The default is to send the implementation identification
1803				information.
1804	
1805		nfsd.nfs4_disable_idmapping=
1806				[NFSv4] When set to the default of '1', the NFSv4
1807				server will return only numeric uids and gids to
1808				clients using auth_sys, and will accept numeric uids
1809				and gids from such clients.  This is intended to ease
1810				migration from NFSv2/v3.
1811	
1812		objlayoutdriver.osd_login_prog=
1813				[NFS] [OBJLAYOUT] sets the pathname to the program which
1814				is used to automatically discover and login into new
1815				osd-targets. Please see:
1816				Documentation/filesystems/pnfs.txt for more explanations
1817	
1818		nmi_debug=	[KNL,AVR32,SH] Specify one or more actions to take
1819				when a NMI is triggered.
1820				Format: [state][,regs][,debounce][,die]
1821	
1822		nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels
1823				Format: [panic,][nopanic,][num]
1824				Valid num: 0
1825				0 - turn nmi_watchdog off
1826				When panic is specified, panic when an NMI watchdog
1827				timeout occurs (or 'nopanic' to override the opposite
1828				default).
1829				This is useful when you use a panic=... timeout and
1830				need the box quickly up again.
1831	
1832		netpoll.carrier_timeout=
1833				[NET] Specifies amount of time (in seconds) that
1834				netpoll should wait for a carrier. By default netpoll
1835				waits 4 seconds.
1836	
1837		no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
1838				emulation library even if a 387 maths coprocessor
1839				is present.
1840	
1841		no_console_suspend
1842				[HW] Never suspend the console
1843				Disable suspending of consoles during suspend and
1844				hibernate operations.  Once disabled, debugging
1845				messages can reach various consoles while the rest
1846				of the system is being put to sleep (ie, while
1847				debugging driver suspend/resume hooks).  This may
1848				not work reliably with all consoles, but is known
1849				to work with serial and VGA consoles.
1850				To facilitate more flexible debugging, we also add
1851				console_suspend, a printk module parameter to control
1852				it. Users could use console_suspend (usually
1853				/sys/module/printk/parameters/console_suspend) to
1854				turn on/off it dynamically.
1855	
1856		noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
1857				caches in the slab allocator.  Saves per-node memory,
1858				but will impact performance.
1859	
1860		noalign		[KNL,ARM]
1861	
1862		noapic		[SMP,APIC] Tells the kernel to not make use of any
1863				IOAPICs that may be present in the system.
1864	
1865		noautogroup	Disable scheduler automatic task group creation.
1866	
1867		nobats		[PPC] Do not use BATs for mapping kernel lowmem
1868				on "Classic" PPC cores.
1869	
1870		nocache		[ARM]
1871	
1872		noclflush	[BUGS=X86] Don't use the CLFLUSH instruction
1873	
1874		nodelayacct	[KNL] Disable per-task delay accounting
1875	
1876		nodisconnect	[HW,SCSI,M68K] Disables SCSI disconnects.
1877	
1878		nodsp		[SH] Disable hardware DSP at boot time.
1879	
1880		noefi		[X86] Disable EFI runtime services support.
1881	
1882		noexec		[IA-64]
1883	
1884		noexec		[X86]
1885				On X86-32 available only on PAE configured kernels.
1886				noexec=on: enable non-executable mappings (default)
1887				noexec=off: disable non-executable mappings
1888	
1889		nosmap		[X86]
1890				Disable SMAP (Supervisor Mode Access Prevention)
1891				even if it is supported by processor.
1892	
1893		nosmep		[X86]
1894				Disable SMEP (Supervisor Mode Execution Prevention)
1895				even if it is supported by processor.
1896	
1897		noexec32	[X86-64]
1898				This affects only 32-bit executables.
1899				noexec32=on: enable non-executable mappings (default)
1900					read doesn't imply executable mappings
1901				noexec32=off: disable non-executable mappings
1902					read implies executable mappings
1903	
1904		nofpu		[SH] Disable hardware FPU at boot time.
1905	
1906		nofxsr		[BUGS=X86-32] Disables x86 floating point extended
1907				register save and restore. The kernel will only save
1908				legacy floating-point registers on task switch.
1909	
1910		noxsave		[BUGS=X86] Disables x86 extended register state save
1911				and restore using xsave. The kernel will fallback to
1912				enabling legacy floating-point and sse state.
1913	
1914		eagerfpu=	[X86]
1915				on	enable eager fpu restore
1916				off	disable eager fpu restore
1917				auto	selects the default scheme, which automatically
1918					enables eagerfpu restore for xsaveopt.
1919	
1920		nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1921				wfi(ARM) instruction doesn't work correctly and not to
1922				use it. This is also useful when using JTAG debugger.
1923	
1924		no_file_caps	Tells the kernel not to honor file capabilities.  The
1925				only way then for a file to be executed with privilege
1926				is to be setuid root or executed by root.
1927	
1928		nohalt		[IA-64] Tells the kernel not to use the power saving
1929				function PAL_HALT_LIGHT when idle. This increases
1930				power-consumption. On the positive side, it reduces
1931				interrupt wake-up latency, which may improve performance
1932				in certain environments such as networked servers or
1933				real-time systems.
1934	
1935		nohz=		[KNL] Boottime enable/disable dynamic ticks
1936				Valid arguments: on, off
1937				Default: on
1938	
1939		noiotrap	[SH] Disables trapped I/O port accesses.
1940	
1941		noirqdebug	[X86-32] Disables the code which attempts to detect and
1942				disable unhandled interrupt sources.
1943	
1944		no_timer_check	[X86,APIC] Disables the code which tests for
1945				broken timer IRQ sources.
1946	
1947		noisapnp	[ISAPNP] Disables ISA PnP code.
1948	
1949		noinitrd	[RAM] Tells the kernel not to load any configured
1950				initial RAM disk.
1951	
1952		nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt
1953				remapping.
1954				[Deprecated - use intremap=off]
1955	
1956		nointroute	[IA-64]
1957	
1958		nojitter	[IA-64] Disables jitter checking for ITC timers.
1959	
1960		no-kvmclock	[X86,KVM] Disable paravirtualized KVM clock driver
1961	
1962		no-kvmapf	[X86,KVM] Disable paravirtualized asynchronous page
1963				fault handling.
1964	
1965		no-steal-acc    [X86,KVM] Disable paravirtualized steal time accounting.
1966				steal time is computed, but won't influence scheduler
1967				behaviour
1968	
1969		nolapic		[X86-32,APIC] Do not enable or use the local APIC.
1970	
1971		nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
1972	
1973		noltlbs		[PPC] Do not use large page/tlb entries for kernel
1974				lowmem mapping on PPC40x.
1975	
1976		nomca		[IA-64] Disable machine check abort handling
1977	
1978		nomce		[X86-32] Machine Check Exception
1979	
1980		nomfgpt		[X86-32] Disable Multi-Function General Purpose
1981				Timer usage (for AMD Geode machines).
1982	
1983		nonmi_ipi	[X86] Disable using NMI IPIs during panic/reboot to
1984				shutdown the other cpus.  Instead use the REBOOT_VECTOR
1985				irq.
1986	
1987		nomodule	Disable module load
1988	
1989		nopat		[X86] Disable PAT (page attribute table extension of
1990				pagetables) support.
1991	
1992		norandmaps	Don't use address space randomization.  Equivalent to
1993				echo 0 > /proc/sys/kernel/randomize_va_space
1994	
1995		noreplace-paravirt	[X86,IA-64,PV_OPS] Don't patch paravirt_ops
1996	
1997		noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
1998				with UP alternatives
1999	
2000		noresidual	[PPC] Don't use residual data on PReP machines.
2001	
2002		nordrand	[X86] Disable the direct use of the RDRAND
2003				instruction even if it is supported by the
2004				processor.  RDRAND is still available to user
2005				space applications.
2006	
2007		noresume	[SWSUSP] Disables resume and restores original swap
2008				space.
2009	
2010		no-scroll	[VGA] Disables scrollback.
2011				This is required for the Braillex ib80-piezo Braille
2012				reader made by F.H. Papenmeier (Germany).
2013	
2014		nosbagart	[IA-64]
2015	
2016		nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
2017	
2018		nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
2019				and disable the IO APIC.  legacy for "maxcpus=0".
2020	
2021		nosoftlockup	[KNL] Disable the soft-lockup detector.
2022	
2023		nosync		[HW,M68K] Disables sync negotiation for all devices.
2024	
2025		notsc		[BUGS=X86-32] Disable Time Stamp Counter
2026	
2027		nousb		[USB] Disable the USB subsystem
2028	
2029		nowatchdog	[KNL] Disable the lockup detector (NMI watchdog).
2030	
2031		nowb		[ARM]
2032	
2033		nox2apic	[X86-64,APIC] Do not enable x2APIC mode.
2034	
2035		cpu0_hotplug	[X86] Turn on CPU0 hotplug feature when
2036				CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
2037				Some features depend on CPU0. Known dependencies are:
2038				1. Resume from suspend/hibernate depends on CPU0.
2039				Suspend/hibernate will fail if CPU0 is offline and you
2040				need to online CPU0 before suspend/hibernate.
2041				2. PIC interrupts also depend on CPU0. CPU0 can't be
2042				removed if a PIC interrupt is detected.
2043				It's said poweroff/reboot may depend on CPU0 on some
2044				machines although I haven't seen such issues so far
2045				after CPU0 is offline on a few tested machines.
2046				If the dependencies are under your control, you can
2047				turn on cpu0_hotplug.
2048	
2049		nptcg=		[IA-64] Override max number of concurrent global TLB
2050				purges which is reported from either PAL_VM_SUMMARY or
2051				SAL PALO.
2052	
2053		nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
2054				could support.  nr_cpus=n : n >= 1 limits the kernel to
2055				supporting 'n' processors. Later in runtime you can not
2056				use hotplug cpu feature to put more cpu back to online.
2057				just like you compile the kernel NR_CPUS=n
2058	
2059		nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
2060	
2061		numa_balancing=	[KNL,X86] Enable or disable automatic NUMA balancing.
2062				Allowed values are enable and disable
2063	
2064		numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2065				one of ['zone', 'node', 'default'] can be specified
2066				This can be set from sysctl after boot.
2067				See Documentation/sysctl/vm.txt for details.
2068	
2069		ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
2070				See Documentation/debugging-via-ohci1394.txt for more
2071				info.
2072	
2073		olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2074				Rather than timing out after 20 ms if an EC
2075				command is not properly ACKed, override the length
2076				of the timeout.  We have interrupts disabled while
2077				waiting for the ACK, so if this is set too high
2078				interrupts *may* be lost!
2079	
2080		omap_mux=	[OMAP] Override bootloader pin multiplexing.
2081				Format: <mux_mode0.mode_name=value>...
2082				For example, to override I2C bus2:
2083				omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2084	
2085		oprofile.timer=	[HW]
2086				Use timer interrupt instead of performance counters
2087	
2088		oprofile.cpu_type=	Force an oprofile cpu type
2089				This might be useful if you have an older oprofile
2090				userland or if you want common events.
2091				Format: { arch_perfmon }
2092				arch_perfmon: [X86] Force use of architectural
2093					perfmon on Intel CPUs instead of the
2094					CPU specific event set.
2095				timer: [X86] Force use of architectural NMI
2096					timer mode (see also oprofile.timer
2097					for generic hr timer mode)
2098					[s390] Force legacy basic mode sampling
2099	                                (report cpu_type "timer")
2100	
2101		oops=panic	Always panic on oopses. Default is to just kill the
2102				process, but there is a small probability of
2103				deadlocking the machine.
2104				This will also cause panics on machine check exceptions.
2105				Useful together with panic=30 to trigger a reboot.
2106	
2107		OSS		[HW,OSS]
2108				See Documentation/sound/oss/oss-parameters.txt
2109	
2110		panic=		[KNL] Kernel behaviour on panic: delay <timeout>
2111				timeout > 0: seconds before rebooting
2112				timeout = 0: wait forever
2113				timeout < 0: reboot immediately
2114				Format: <timeout>
2115	
2116		parkbd.port=	[HW] Parallel port number the keyboard adapter is
2117				connected to, default is 0.
2118				Format: <parport#>
2119		parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
2120				0 for XT, 1 for AT (default is AT).
2121				Format: <mode>
2122	
2123		parport=	[HW,PPT] Specify parallel ports. 0 disables.
2124				Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2125				Use 'auto' to force the driver to use any
2126				IRQ/DMA settings detected (the default is to
2127				ignore detected IRQ/DMA settings because of
2128				possible conflicts). You can specify the base
2129				address, IRQ, and DMA settings; IRQ and DMA
2130				should be numbers, or 'auto' (for using detected
2131				settings on that particular port), or 'nofifo'
2132				(to avoid using a FIFO even if it is detected).
2133				Parallel ports are assigned in the order they
2134				are specified on the command line, starting
2135				with parport0.
2136	
2137		parport_init_mode=	[HW,PPT]
2138				Configure VIA parallel port to operate in
2139				a specific mode. This is necessary on Pegasos
2140				computer where firmware has no options for setting
2141				up parallel port mode and sets it to spp.
2142				Currently this function knows 686a and 8231 chips.
2143				Format: [spp|ps2|epp|ecp|ecpepp]
2144	
2145		pause_on_oops=
2146				Halt all CPUs after the first oops has been printed for
2147				the specified number of seconds.  This is to be used if
2148				your oopses keep scrolling off the screen.
2149	
2150		pcbit=		[HW,ISDN]
2151	
2152		pcd.		[PARIDE]
2153				See header of drivers/block/paride/pcd.c.
2154				See also Documentation/blockdev/paride.txt.
2155	
2156		pci=option[,option...]	[PCI] various PCI subsystem options:
2157			earlydump	[X86] dump PCI config space before the kernel
2158				        changes anything
2159			off		[X86] don't probe for the PCI bus
2160			bios		[X86-32] force use of PCI BIOS, don't access
2161					the hardware directly. Use this if your machine
2162					has a non-standard PCI host bridge.
2163			nobios		[X86-32] disallow use of PCI BIOS, only direct
2164					hardware access methods are allowed. Use this
2165					if you experience crashes upon bootup and you
2166					suspect they are caused by the BIOS.
2167			conf1		[X86] Force use of PCI Configuration
2168					Mechanism 1.
2169			conf2		[X86] Force use of PCI Configuration
2170					Mechanism 2.
2171			noaer		[PCIE] If the PCIEAER kernel config parameter is
2172					enabled, this kernel boot option can be used to
2173					disable the use of PCIE advanced error reporting.
2174			nodomains	[PCI] Disable support for multiple PCI
2175					root domains (aka PCI segments, in ACPI-speak).
2176			nommconf	[X86] Disable use of MMCONFIG for PCI
2177					Configuration
2178			check_enable_amd_mmconf [X86] check for and enable
2179					properly configured MMIO access to PCI
2180					config space on AMD family 10h CPU
2181			nomsi		[MSI] If the PCI_MSI kernel config parameter is
2182					enabled, this kernel boot option can be used to
2183					disable the use of MSI interrupts system-wide.
2184			noioapicquirk	[APIC] Disable all boot interrupt quirks.
2185					Safety option to keep boot IRQs enabled. This
2186					should never be necessary.
2187			ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
2188					primary IO-APIC for bridges that cannot disable
2189					boot IRQs. This fixes a source of spurious IRQs
2190					when the system masks IRQs.
2191			noioapicreroute	[APIC] Disable workaround that uses the
2192					boot IRQ equivalent of an IRQ that connects to
2193					a chipset where boot IRQs cannot be disabled.
2194					The opposite of ioapicreroute.
2195			biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
2196					routing table. These calls are known to be buggy
2197					on several machines and they hang the machine
2198					when used, but on other computers it's the only
2199					way to get the interrupt routing table. Try
2200					this option if the kernel is unable to allocate
2201					IRQs or discover secondary PCI buses on your
2202					motherboard.
2203			rom		[X86] Assign address space to expansion ROMs.
2204					Use with caution as certain devices share
2205					address decoders between ROMs and other
2206					resources.
2207			norom		[X86] Do not assign address space to
2208					expansion ROMs that do not already have
2209					BIOS assigned address ranges.
2210			nobar		[X86] Do not assign address space to the
2211					BARs that weren't assigned by the BIOS.
2212			irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
2213					assigned automatically to PCI devices. You can
2214					make the kernel exclude IRQs of your ISA cards
2215					this way.
2216			pirqaddr=0xAAAAA	[X86] Specify the physical address
2217					of the PIRQ table (normally generated
2218					by the BIOS) if it is outside the
2219					F0000h-100000h range.
2220			lastbus=N	[X86] Scan all buses thru bus #N. Can be
2221					useful if the kernel is unable to find your
2222					secondary buses and you want to tell it
2223					explicitly which ones they are.
2224			assign-busses	[X86] Always assign all PCI bus
2225					numbers ourselves, overriding
2226					whatever the firmware may have done.
2227			usepirqmask	[X86] Honor the possible IRQ mask stored
2228					in the BIOS $PIR table. This is needed on
2229					some systems with broken BIOSes, notably
2230					some HP Pavilion N5400 and Omnibook XE3
2231					notebooks. This will have no effect if ACPI
2232					IRQ routing is enabled.
2233			noacpi		[X86] Do not use ACPI for IRQ routing
2234					or for PCI scanning.
2235			use_crs		[X86] Use PCI host bridge window information
2236					from ACPI.  On BIOSes from 2008 or later, this
2237					is enabled by default.  If you need to use this,
2238					please report a bug.
2239			nocrs		[X86] Ignore PCI host bridge windows from ACPI.
2240				        If you need to use this, please report a bug.
2241			routeirq	Do IRQ routing for all PCI devices.
2242					This is normally done in pci_enable_device(),
2243					so this option is a temporary workaround
2244					for broken drivers that don't call it.
2245			skip_isa_align	[X86] do not align io start addr, so can
2246					handle more pci cards
2247			firmware	[ARM] Do not re-enumerate the bus but instead
2248					just use the configuration from the
2249					bootloader. This is currently used on
2250					IXP2000 systems where the bus has to be
2251					configured a certain way for adjunct CPUs.
2252			noearly		[X86] Don't do any early type 1 scanning.
2253					This might help on some broken boards which
2254					machine check when some devices' config space
2255					is read. But various workarounds are disabled
2256					and some IOMMU drivers will not work.
2257			bfsort		Sort PCI devices into breadth-first order.
2258					This sorting is done to get a device
2259					order compatible with older (<= 2.4) kernels.
2260			nobfsort	Don't sort PCI devices into breadth-first order.
2261			pcie_bus_tune_off	Disable PCIe MPS (Max Payload Size)
2262					tuning and use the BIOS-configured MPS defaults.
2263			pcie_bus_safe	Set every device's MPS to the largest value
2264					supported by all devices below the root complex.
2265			pcie_bus_perf	Set device MPS to the largest allowable MPS
2266					based on its parent bus. Also set MRRS (Max
2267					Read Request Size) to the largest supported
2268					value (no larger than the MPS that the device
2269					or bus can support) for best performance.
2270			pcie_bus_peer2peer	Set every device's MPS to 128B, which
2271					every device is guaranteed to support. This
2272					configuration allows peer-to-peer DMA between
2273					any pair of devices, possibly at the cost of
2274					reduced performance.  This also guarantees
2275					that hot-added devices will work.
2276			cbiosize=nn[KMG]	The fixed amount of bus space which is
2277					reserved for the CardBus bridge's IO window.
2278					The default value is 256 bytes.
2279			cbmemsize=nn[KMG]	The fixed amount of bus space which is
2280					reserved for the CardBus bridge's memory
2281					window. The default value is 64 megabytes.
2282			resource_alignment=
2283					Format:
2284					[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2285					Specifies alignment and device to reassign
2286					aligned memory resources.
2287					If <order of align> is not specified,
2288					PAGE_SIZE is used as alignment.
2289					PCI-PCI bridge can be specified, if resource
2290					windows need to be expanded.
2291			ecrc=		Enable/disable PCIe ECRC (transaction layer
2292					end-to-end CRC checking).
2293					bios: Use BIOS/firmware settings. This is the
2294					the default.
2295					off: Turn ECRC off
2296					on: Turn ECRC on.
2297			hpiosize=nn[KMG]	The fixed amount of bus space which is
2298					reserved for hotplug bridge's IO window.
2299					Default size is 256 bytes.
2300			hpmemsize=nn[KMG]	The fixed amount of bus space which is
2301					reserved for hotplug bridge's memory window.
2302					Default size is 2 megabytes.
2303			realloc=	Enable/disable reallocating PCI bridge resources
2304					if allocations done by BIOS are too small to
2305					accommodate resources required by all child
2306					devices.
2307					off: Turn realloc off
2308					on: Turn realloc on
2309			realloc		same as realloc=on
2310			noari		do not use PCIe ARI.
2311			pcie_scan_all	Scan all possible PCIe devices.  Otherwise we
2312					only look for one device below a PCIe downstream
2313					port.
2314	
2315		pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
2316				Management.
2317			off	Disable ASPM.
2318			force	Enable ASPM even on devices that claim not to support it.
2319				WARNING: Forcing ASPM on may cause system lockups.
2320	
2321		pcie_hp=	[PCIE] PCI Express Hotplug driver options:
2322			nomsi	Do not use MSI for PCI Express Native Hotplug (this
2323				makes all PCIe ports use INTx for hotplug services).
2324	
2325		pcie_ports=	[PCIE] PCIe ports handling:
2326			auto	Ask the BIOS whether or not to use native PCIe services
2327				associated with PCIe ports (PME, hot-plug, AER).  Use
2328				them only if that is allowed by the BIOS.
2329			native	Use native PCIe services associated with PCIe ports
2330				unconditionally.
2331			compat	Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2332				ports driver.
2333	
2334		pcie_pme=	[PCIE,PM] Native PCIe PME signaling options:
2335			nomsi	Do not use MSI for native PCIe PME signaling (this makes
2336				all PCIe root ports use INTx for all services).
2337	
2338		pcmv=		[HW,PCMCIA] BadgePAD 4
2339	
2340		pd.		[PARIDE]
2341				See Documentation/blockdev/paride.txt.
2342	
2343		pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
2344				boot time.
2345				Format: { 0 | 1 }
2346				See arch/parisc/kernel/pdc_chassis.c
2347	
2348		percpu_alloc=	Select which percpu first chunk allocator to use.
2349				Currently supported values are "embed" and "page".
2350				Archs may support subset or none of the	selections.
2351				See comments in mm/percpu.c for details on each
2352				allocator.  This parameter is primarily	for debugging
2353				and performance comparison.
2354	
2355		pf.		[PARIDE]
2356				See Documentation/blockdev/paride.txt.
2357	
2358		pg.		[PARIDE]
2359				See Documentation/blockdev/paride.txt.
2360	
2361		pirq=		[SMP,APIC] Manual mp-table setup
2362				See Documentation/x86/i386/IO-APIC.txt.
2363	
2364		plip=		[PPT,NET] Parallel port network link
2365				Format: { parport<nr> | timid | 0 }
2366				See also Documentation/parport.txt.
2367	
2368		pmtmr=		[X86] Manual setup of pmtmr I/O Port.
2369				Override pmtimer IOPort with a hex value.
2370				e.g. pmtmr=0x508
2371	
2372		pnp.debug=1	[PNP]
2373				Enable PNP debug messages (depends on the
2374				CONFIG_PNP_DEBUG_MESSAGES option).  Change at run-time
2375				via /sys/module/pnp/parameters/debug.  We always show
2376				current resource usage; turning this on also shows
2377				possible settings and some assignment information.
2378	
2379		pnpacpi=	[ACPI]
2380				{ off }
2381	
2382		pnpbios=	[ISAPNP]
2383				{ on | off | curr | res | no-curr | no-res }
2384	
2385		pnp_reserve_irq=
2386				[ISAPNP] Exclude IRQs for the autoconfiguration
2387	
2388		pnp_reserve_dma=
2389				[ISAPNP] Exclude DMAs for the autoconfiguration
2390	
2391		pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
2392				Ranges are in pairs (I/O port base and size).
2393	
2394		pnp_reserve_mem=
2395				[ISAPNP] Exclude memory regions for the
2396				autoconfiguration.
2397				Ranges are in pairs (memory base and size).
2398	
2399		ports=		[IP_VS_FTP] IPVS ftp helper module
2400				Default is 21.
2401				Up to 8 (IP_VS_APP_MAX_PORTS) ports
2402				may be specified.
2403				Format: <port>,<port>....
2404	
2405		print-fatal-signals=
2406				[KNL] debug: print fatal signals
2407	
2408				If enabled, warn about various signal handling
2409				related application anomalies: too many signals,
2410				too many POSIX.1 timers, fatal signals causing a
2411				coredump - etc.
2412	
2413				If you hit the warning due to signal overflow,
2414				you might want to try "ulimit -i unlimited".
2415	
2416				default: off.
2417	
2418		printk.always_kmsg_dump=
2419				Trigger kmsg_dump for cases other than kernel oops or
2420				panics
2421				Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
2422				default: disabled
2423	
2424		printk.time=	Show timing data prefixed to each printk message line
2425				Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
2426	
2427		processor.max_cstate=	[HW,ACPI]
2428				Limit processor to maximum C-state
2429				max_cstate=9 overrides any DMI blacklist limit.
2430	
2431		processor.nocst	[HW,ACPI]
2432				Ignore the _CST method to determine C-states,
2433				instead using the legacy FADT method
2434	
2435		profile=	[KNL] Enable kernel profiling via /proc/profile
2436				Format: [schedule,]<number>
2437				Param: "schedule" - profile schedule points.
2438				Param: <number> - step/bucket size as a power of 2 for
2439					statistical time based profiling.
2440				Param: "sleep" - profile D-state sleeping (millisecs).
2441					Requires CONFIG_SCHEDSTATS
2442				Param: "kvm" - profile VM exits.
2443	
2444		prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk
2445				before loading.
2446				See Documentation/blockdev/ramdisk.txt.
2447	
2448		psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
2449				probe for; one of (bare|imps|exps|lifebook|any).
2450		psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
2451				per second.
2452		psmouse.resetafter=	[HW,MOUSE]
2453				Try to reset the device after so many bad packets
2454				(0 = never).
2455		psmouse.resolution=
2456				[HW,MOUSE] Set desired mouse resolution, in dpi.
2457		psmouse.smartscroll=
2458				[HW,MOUSE] Controls Logitech smartscroll autorepeat.
2459				0 = disabled, 1 = enabled (default).
2460	
2461		pstore.backend=	Specify the name of the pstore backend to use
2462	
2463		pt.		[PARIDE]
2464				See Documentation/blockdev/paride.txt.
2465	
2466		pty.legacy_count=
2467				[KNL] Number of legacy pty's. Overwrites compiled-in
2468				default number.
2469	
2470		quiet		[KNL] Disable most log messages
2471	
2472		r128=		[HW,DRM]
2473	
2474		raid=		[HW,RAID]
2475				See Documentation/md.txt.
2476	
2477		ramdisk_blocksize=	[RAM]
2478				See Documentation/blockdev/ramdisk.txt.
2479	
2480		ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
2481				See Documentation/blockdev/ramdisk.txt.
2482	
2483		rcu_nocbs=	[KNL,BOOT]
2484				In kernels built with CONFIG_RCU_NOCB_CPU=y, set
2485				the specified list of CPUs to be no-callback CPUs.
2486				Invocation of these CPUs' RCU callbacks will
2487				be offloaded to "rcuoN" kthreads created for
2488				that purpose.  This reduces OS jitter on the
2489				offloaded CPUs, which can be useful for HPC and
2490				real-time workloads.  It can also improve energy
2491				efficiency for asymmetric multiprocessors.
2492	
2493		rcu_nocb_poll	[KNL,BOOT]
2494				Rather than requiring that offloaded CPUs
2495				(specified by rcu_nocbs= above) explicitly
2496				awaken the corresponding "rcuoN" kthreads,
2497				make these kthreads poll for callbacks.
2498				This improves the real-time response for the
2499				offloaded CPUs by relieving them of the need to
2500				wake up the corresponding kthread, but degrades
2501				energy efficiency by requiring that the kthreads
2502				periodically wake up to do the polling.
2503	
2504		rcutree.blimit=	[KNL,BOOT]
2505				Set maximum number of finished RCU callbacks to process
2506				in one batch.
2507	
2508		rcutree.fanout_leaf=	[KNL,BOOT]
2509				Increase the number of CPUs assigned to each
2510				leaf rcu_node structure.  Useful for very large
2511				systems.
2512	
2513		rcutree.qhimark=	[KNL,BOOT]
2514				Set threshold of queued
2515				RCU callbacks over which batch limiting is disabled.
2516	
2517		rcutree.qlowmark=	[KNL,BOOT]
2518				Set threshold of queued RCU callbacks below which
2519				batch limiting is re-enabled.
2520	
2521		rcutree.rcu_cpu_stall_suppress=	[KNL,BOOT]
2522				Suppress RCU CPU stall warning messages.
2523	
2524		rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
2525				Set timeout for RCU CPU stall warning messages.
2526	
2527		rcutree.jiffies_till_first_fqs= [KNL,BOOT]
2528				Set delay from grace-period initialization to
2529				first attempt to force quiescent states.
2530				Units are jiffies, minimum value is zero,
2531				and maximum value is HZ.
2532	
2533		rcutree.jiffies_till_next_fqs= [KNL,BOOT]
2534				Set delay between subsequent attempts to force
2535				quiescent states.  Units are jiffies, minimum
2536				value is one, and maximum value is HZ.
2537	
2538		rcutorture.fqs_duration= [KNL,BOOT]
2539				Set duration of force_quiescent_state bursts.
2540	
2541		rcutorture.fqs_holdoff= [KNL,BOOT]
2542				Set holdoff time within force_quiescent_state bursts.
2543	
2544		rcutorture.fqs_stutter= [KNL,BOOT]
2545				Set wait time between force_quiescent_state bursts.
2546	
2547		rcutorture.irqreader= [KNL,BOOT]
2548				Test RCU readers from irq handlers.
2549	
2550		rcutorture.n_barrier_cbs= [KNL,BOOT]
2551				Set callbacks/threads for rcu_barrier() testing.
2552	
2553		rcutorture.nfakewriters= [KNL,BOOT]
2554				Set number of concurrent RCU writers.  These just
2555				stress RCU, they don't participate in the actual
2556				test, hence the "fake".
2557	
2558		rcutorture.nreaders= [KNL,BOOT]
2559				Set number of RCU readers.
2560	
2561		rcutorture.onoff_holdoff= [KNL,BOOT]
2562				Set time (s) after boot for CPU-hotplug testing.
2563	
2564		rcutorture.onoff_interval= [KNL,BOOT]
2565				Set time (s) between CPU-hotplug operations, or
2566				zero to disable CPU-hotplug testing.
2567	
2568		rcutorture.shuffle_interval= [KNL,BOOT]
2569				Set task-shuffle interval (s).  Shuffling tasks
2570				allows some CPUs to go into dyntick-idle mode
2571				during the rcutorture test.
2572	
2573		rcutorture.shutdown_secs= [KNL,BOOT]
2574				Set time (s) after boot system shutdown.  This
2575				is useful for hands-off automated testing.
2576	
2577		rcutorture.stall_cpu= [KNL,BOOT]
2578				Duration of CPU stall (s) to test RCU CPU stall
2579				warnings, zero to disable.
2580	
2581		rcutorture.stall_cpu_holdoff= [KNL,BOOT]
2582				Time to wait (s) after boot before inducing stall.
2583	
2584		rcutorture.stat_interval= [KNL,BOOT]
2585				Time (s) between statistics printk()s.
2586	
2587		rcutorture.stutter= [KNL,BOOT]
2588				Time (s) to stutter testing, for example, specifying
2589				five seconds causes the test to run for five seconds,
2590				wait for five seconds, and so on.  This tests RCU's
2591				ability to transition abruptly to and from idle.
2592	
2593		rcutorture.test_boost= [KNL,BOOT]
2594				Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
2595				"Maybe" means test if the RCU implementation
2596				under test support RCU priority boosting.
2597	
2598		rcutorture.test_boost_duration= [KNL,BOOT]
2599				Duration (s) of each individual boost test.
2600	
2601		rcutorture.test_boost_interval= [KNL,BOOT]
2602				Interval (s) between each boost test.
2603	
2604		rcutorture.test_no_idle_hz= [KNL,BOOT]
2605				Test RCU's dyntick-idle handling.  See also the
2606				rcutorture.shuffle_interval parameter.
2607	
2608		rcutorture.torture_type= [KNL,BOOT]
2609				Specify the RCU implementation to test.
2610	
2611		rcutorture.verbose= [KNL,BOOT]
2612				Enable additional printk() statements.
2613	
2614		rdinit=		[KNL]
2615				Format: <full_path>
2616				Run specified binary instead of /init from the ramdisk,
2617				used for early userspace startup. See initrd.
2618	
2619		reboot=		[BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2620				Format: <reboot_mode>[,<reboot_mode2>[,...]]
2621				See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2622	
2623		relax_domain_level=
2624				[KNL, SMP] Set scheduler's default relax_domain_level.
2625				See Documentation/cgroups/cpusets.txt.
2626	
2627		reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area
2628	
2629		reservetop=	[X86-32]
2630				Format: nn[KMG]
2631				Reserves a hole at the top of the kernel virtual
2632				address space.
2633	
2634		reservelow=	[X86]
2635				Format: nn[K]
2636				Set the amount of memory to reserve for BIOS at
2637				the bottom of the address space.
2638	
2639		reset_devices	[KNL] Force drivers to reset the underlying device
2640				during initialization.
2641	
2642		resume=		[SWSUSP]
2643				Specify the partition device for software suspend
2644				Format:
2645				{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
2646	
2647		resume_offset=	[SWSUSP]
2648				Specify the offset from the beginning of the partition
2649				given by "resume=" at which the swap header is located,
2650				in <PAGE_SIZE> units (needed only for swap files).
2651				See  Documentation/power/swsusp-and-swap-files.txt
2652	
2653		resumedelay=	[HIBERNATION] Delay (in seconds) to pause before attempting to
2654				read the resume files
2655	
2656		resumewait	[HIBERNATION] Wait (indefinitely) for resume device to show up.
2657				Useful for devices that are detected asynchronously
2658				(e.g. USB and MMC devices).
2659	
2660		hibernate=	[HIBERNATION]
2661			noresume	Don't check if there's a hibernation image
2662					present during boot.
2663			nocompress	Don't compress/decompress hibernation images.
2664	
2665		retain_initrd	[RAM] Keep initrd memory after extraction
2666	
2667		rhash_entries=	[KNL,NET]
2668				Set number of hash buckets for route cache
2669	
2670		riscom8=	[HW,SERIAL]
2671				Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2672	
2673		ro		[KNL] Mount root device read-only on boot
2674	
2675		root=		[KNL] Root filesystem
2676				See name_to_dev_t comment in init/do_mounts.c.
2677	
2678		rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
2679				mount the root filesystem
2680	
2681		rootflags=	[KNL] Set root filesystem mount option string
2682	
2683		rootfstype=	[KNL] Set root filesystem type
2684	
2685		rootwait	[KNL] Wait (indefinitely) for root device to show up.
2686				Useful for devices that are detected asynchronously
2687				(e.g. USB and MMC devices).
2688	
2689		rw		[KNL] Mount root device read-write on boot
2690	
2691		S		[KNL] Run init in single mode
2692	
2693		sa1100ir	[NET]
2694				See drivers/net/irda/sa1100_ir.c.
2695	
2696		sbni=		[NET] Granch SBNI12 leased line adapter
2697	
2698		sched_debug	[KNL] Enables verbose scheduler debug messages.
2699	
2700		skew_tick=	[KNL] Offset the periodic timer tick per cpu to mitigate
2701				xtime_lock contention on larger systems, and/or RCU lock
2702				contention on all systems with CONFIG_MAXSMP set.
2703				Format: { "0" | "1" }
2704				0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
2705				1 -- enable.
2706				Note: increases power consumption, thus should only be
2707				enabled if running jitter sensitive (HPC/RT) workloads.
2708	
2709		security=	[SECURITY] Choose a security module to enable at boot.
2710				If this boot parameter is not specified, only the first
2711				security module asking for security registration will be
2712				loaded. An invalid security module name will be treated
2713				as if no module has been chosen.
2714	
2715		selinux=	[SELINUX] Disable or enable SELinux at boot time.
2716				Format: { "0" | "1" }
2717				See security/selinux/Kconfig help text.
2718				0 -- disable.
2719				1 -- enable.
2720				Default value is set via kernel config option.
2721				If enabled at boot time, /selinux/disable can be used
2722				later to disable prior to initial policy load.
2723	
2724		apparmor=	[APPARMOR] Disable or enable AppArmor at boot time
2725				Format: { "0" | "1" }
2726				See security/apparmor/Kconfig help text
2727				0 -- disable.
2728				1 -- enable.
2729				Default value is set via kernel config option.
2730	
2731		serialnumber	[BUGS=X86-32]
2732	
2733		shapers=	[NET]
2734				Maximal number of shapers.
2735	
2736		show_msr=	[x86] show boot-time MSR settings
2737				Format: { <integer> }
2738				Show boot-time (BIOS-initialized) MSR settings.
2739				The parameter means the number of CPUs to show,
2740				for example 1 means boot CPU only.
2741	
2742		simeth=		[IA-64]
2743		simscsi=
2744	
2745		slram=		[HW,MTD]
2746	
2747		slab_max_order=	[MM, SLAB]
2748				Determines the maximum allowed order for slabs.
2749				A high setting may cause OOMs due to memory
2750				fragmentation.  Defaults to 1 for systems with
2751				more than 32MB of RAM, 0 otherwise.
2752	
2753		slub_debug[=options[,slabs]]	[MM, SLUB]
2754				Enabling slub_debug allows one to determine the
2755				culprit if slab objects become corrupted. Enabling
2756				slub_debug can create guard zones around objects and
2757				may poison objects when not in use. Also tracks the
2758				last alloc / free. For more information see
2759				Documentation/vm/slub.txt.
2760	
2761		slub_max_order= [MM, SLUB]
2762				Determines the maximum allowed order for slabs.
2763				A high setting may cause OOMs due to memory
2764				fragmentation. For more information see
2765				Documentation/vm/slub.txt.
2766	
2767		slub_min_objects=	[MM, SLUB]
2768				The minimum number of objects per slab. SLUB will
2769				increase the slab order up to slub_max_order to
2770				generate a sufficiently large slab able to contain
2771				the number of objects indicated. The higher the number
2772				of objects the smaller the overhead of tracking slabs
2773				and the less frequently locks need to be acquired.
2774				For more information see Documentation/vm/slub.txt.
2775	
2776		slub_min_order=	[MM, SLUB]
2777				Determines the minimum page order for slabs. Must be
2778				lower than slub_max_order.
2779				For more information see Documentation/vm/slub.txt.
2780	
2781		slub_nomerge	[MM, SLUB]
2782				Disable merging of slabs with similar size. May be
2783				necessary if there is some reason to distinguish
2784				allocs to different slabs. Debug options disable
2785				merging on their own.
2786				For more information see Documentation/vm/slub.txt.
2787	
2788		smart2=		[HW]
2789				Format: <io1>[,<io2>[,...,<io8>]]
2790	
2791		smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
2792		smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
2793		smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
2794		smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
2795		smsc-ircc2.ircc_irq=	[HW] IRQ line
2796		smsc-ircc2.ircc_dma=	[HW] DMA channel
2797		smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2798					0: Toshiba Satellite 1800 (GP data pin select)
2799					1: Fast pin select (default)
2800					2: ATC IRMode
2801	
2802		softlockup_panic=
2803				[KNL] Should the soft-lockup detector generate panics.
2804				Format: <integer>
2805	
2806		sonypi.*=	[HW] Sony Programmable I/O Control Device driver
2807				See Documentation/laptops/sonypi.txt
2808	
2809		specialix=	[HW,SERIAL] Specialix multi-serial port adapter
2810				See Documentation/serial/specialix.txt.
2811	
2812		spia_io_base=	[HW,MTD]
2813		spia_fio_base=
2814		spia_pedr=
2815		spia_peddr=
2816	
2817		stacktrace	[FTRACE]
2818				Enabled the stack tracer on boot up.
2819	
2820		stacktrace_filter=[function-list]
2821				[FTRACE] Limit the functions that the stack tracer
2822				will trace at boot up. function-list is a comma separated
2823				list of functions. This list can be changed at run
2824				time by the stack_trace_filter file in the debugfs
2825				tracing directory. Note, this enables stack tracing
2826				and the stacktrace above is not needed.
2827	
2828		sti=		[PARISC,HW]
2829				Format: <num>
2830				Set the STI (builtin display/keyboard on the HP-PARISC
2831				machines) console (graphic card) which should be used
2832				as the initial boot-console.
2833				See also comment in drivers/video/console/sticore.c.
2834	
2835		sti_font=	[HW]
2836				See comment in drivers/video/console/sticore.c.
2837	
2838		stifb=		[HW]
2839				Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2840	
2841		sunrpc.min_resvport=
2842		sunrpc.max_resvport=
2843				[NFS,SUNRPC]
2844				SunRPC servers often require that client requests
2845				originate from a privileged port (i.e. a port in the
2846				range 0 < portnr < 1024).
2847				An administrator who wishes to reserve some of these
2848				ports for other uses may adjust the range that the
2849				kernel's sunrpc client considers to be privileged
2850				using these two parameters to set the minimum and
2851				maximum port values.
2852	
2853		sunrpc.pool_mode=
2854				[NFS]
2855				Control how the NFS server code allocates CPUs to
2856				service thread pools.  Depending on how many NICs
2857				you have and where their interrupts are bound, this
2858				option will affect which CPUs will do NFS serving.
2859				Note: this parameter cannot be changed while the
2860				NFS server is running.
2861	
2862				auto	    the server chooses an appropriate mode
2863					    automatically using heuristics
2864				global	    a single global pool contains all CPUs
2865				percpu	    one pool for each CPU
2866				pernode	    one pool for each NUMA node (equivalent
2867					    to global on non-NUMA machines)
2868	
2869		sunrpc.tcp_slot_table_entries=
2870		sunrpc.udp_slot_table_entries=
2871				[NFS,SUNRPC]
2872				Sets the upper limit on the number of simultaneous
2873				RPC calls that can be sent from the client to a
2874				server. Increasing these values may allow you to
2875				improve throughput, but will also increase the
2876				amount of memory reserved for use by the client.
2877	
2878		swapaccount[=0|1]
2879				[KNL] Enable accounting of swap in memory resource
2880				controller if no parameter or 1 is given or disable
2881				it if 0 is given (See Documentation/cgroups/memory.txt)
2882	
2883		swiotlb=	[IA-64] Number of I/O TLB slabs
2884	
2885		switches=	[HW,M68k]
2886	
2887		sysfs.deprecated=0|1 [KNL]
2888				Enable/disable old style sysfs layout for old udev
2889				on older distributions. When this option is enabled
2890				very new udev will not work anymore. When this option
2891				is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2892				in older udev will not work anymore.
2893				Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2894				the kernel configuration.
2895	
2896		sysrq_always_enabled
2897				[KNL]
2898				Ignore sysrq setting - this boot parameter will
2899				neutralize any effect of /proc/sys/kernel/sysrq.
2900				Useful for debugging.
2901	
2902		tdfx=		[HW,DRM]
2903	
2904		test_suspend=	[SUSPEND]
2905				Specify "mem" (for Suspend-to-RAM) or "standby" (for
2906				standby suspend) as the system sleep state to briefly
2907				enter during system startup.  The system is woken from
2908				this state using a wakeup-capable RTC alarm.
2909	
2910		thash_entries=	[KNL,NET]
2911				Set number of hash buckets for TCP connection
2912	
2913		thermal.act=	[HW,ACPI]
2914				-1: disable all active trip points in all thermal zones
2915				<degrees C>: override all lowest active trip points
2916	
2917		thermal.crt=	[HW,ACPI]
2918				-1: disable all critical trip points in all thermal zones
2919				<degrees C>: override all critical trip points
2920	
2921		thermal.nocrt=	[HW,ACPI]
2922				Set to disable actions on ACPI thermal zone
2923				critical and hot trip points.
2924	
2925		thermal.off=	[HW,ACPI]
2926				1: disable ACPI thermal control
2927	
2928		thermal.psv=	[HW,ACPI]
2929				-1: disable all passive trip points
2930				<degrees C>: override all passive trip points to this
2931				value
2932	
2933		thermal.tzp=	[HW,ACPI]
2934				Specify global default ACPI thermal zone polling rate
2935				<deci-seconds>: poll all this frequency
2936				0: no polling (default)
2937	
2938		threadirqs	[KNL]
2939				Force threading of all interrupt handlers except those
2940				marked explicitly IRQF_NO_THREAD.
2941	
2942		topology=	[S390]
2943				Format: {off | on}
2944				Specify if the kernel should make use of the cpu
2945				topology information if the hardware supports this.
2946				The scheduler will make use of this information and
2947				e.g. base its process migration decisions on it.
2948				Default is on.
2949	
2950		tp720=		[HW,PS2]
2951	
2952		tpm_suspend_pcr=[HW,TPM]
2953				Format: integer pcr id
2954				Specify that at suspend time, the tpm driver
2955				should extend the specified pcr with zeros,
2956				as a workaround for some chips which fail to
2957				flush the last written pcr on TPM_SaveState.
2958				This will guarantee that all the other pcrs
2959				are saved.
2960	
2961		trace_buf_size=nn[KMG]
2962				[FTRACE] will set tracing buffer size.
2963	
2964		trace_event=[event-list]
2965				[FTRACE] Set and start specified trace events in order
2966				to facilitate early boot debugging.
2967				See also Documentation/trace/events.txt
2968	
2969		trace_options=[option-list]
2970				[FTRACE] Enable or disable tracer options at boot.
2971				The option-list is a comma delimited list of options
2972				that can be enabled or disabled just as if you were
2973				to echo the option name into
2974	
2975				    /sys/kernel/debug/tracing/trace_options
2976	
2977				For example, to enable stacktrace option (to dump the
2978				stack trace of each event), add to the command line:
2979	
2980				      trace_options=stacktrace
2981	
2982				See also Documentation/trace/ftrace.txt "trace options"
2983				section.
2984	
2985		transparent_hugepage=
2986				[KNL]
2987				Format: [always|madvise|never]
2988				Can be used to control the default behavior of the system
2989				with respect to transparent hugepages.
2990				See Documentation/vm/transhuge.txt for more details.
2991	
2992		tsc=		Disable clocksource stability checks for TSC.
2993				Format: <string>
2994				[x86] reliable: mark tsc clocksource as reliable, this
2995				disables clocksource verification at runtime, as well
2996				as the stability checks done at bootup.	Used to enable
2997				high-resolution timer mode on older hardware, and in
2998				virtualized environment.
2999				[x86] noirqtime: Do not use TSC to do irq accounting.
3000				Used to run time disable IRQ_TIME_ACCOUNTING on any
3001				platforms where RDTSC is slow and this accounting
3002				can add overhead.
3003	
3004		turbografx.map[2|3]=	[HW,JOY]
3005				TurboGraFX parallel port interface
3006				Format:
3007				<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
3008				See also Documentation/input/joystick-parport.txt
3009	
3010		udbg-immortal	[PPC] When debugging early kernel crashes that
3011				happen after console_init() and before a proper 
3012				console driver takes over, this boot options might
3013				help "seeing" what's going on.
3014	
3015		uhash_entries=	[KNL,NET]
3016				Set number of hash buckets for UDP/UDP-Lite connections
3017	
3018		uhci-hcd.ignore_oc=
3019				[USB] Ignore overcurrent events (default N).
3020				Some badly-designed motherboards generate lots of
3021				bogus events, for ports that aren't wired to
3022				anything.  Set this parameter to avoid log spamming.
3023				Note that genuine overcurrent events won't be
3024				reported either.
3025	
3026		unknown_nmi_panic
3027				[X86] Cause panic on unknown NMI.
3028	
3029		usbcore.authorized_default=
3030				[USB] Default USB device authorization:
3031				(default -1 = authorized except for wireless USB,
3032				0 = not authorized, 1 = authorized)
3033	
3034		usbcore.autosuspend=
3035				[USB] The autosuspend time delay (in seconds) used
3036				for newly-detected USB devices (default 2).  This
3037				is the time required before an idle device will be
3038				autosuspended.  Devices for which the delay is set
3039				to a negative value won't be autosuspended at all.
3040	
3041		usbcore.usbfs_snoop=
3042				[USB] Set to log all usbfs traffic (default 0 = off).
3043	
3044		usbcore.blinkenlights=
3045				[USB] Set to cycle leds on hubs (default 0 = off).
3046	
3047		usbcore.old_scheme_first=
3048				[USB] Start with the old device initialization
3049				scheme (default 0 = off).
3050	
3051		usbcore.usbfs_memory_mb=
3052				[USB] Memory limit (in MB) for buffers allocated by
3053				usbfs (default = 16, 0 = max = 2047).
3054	
3055		usbcore.use_both_schemes=
3056				[USB] Try the other device initialization scheme
3057				if the first one fails (default 1 = enabled).
3058	
3059		usbcore.initial_descriptor_timeout=
3060				[USB] Specifies timeout for the initial 64-byte
3061	                        USB_REQ_GET_DESCRIPTOR request in milliseconds
3062				(default 5000 = 5.0 seconds).
3063	
3064		usbhid.mousepoll=
3065				[USBHID] The interval which mice are to be polled at.
3066	
3067		usb-storage.delay_use=
3068				[UMS] The delay in seconds before a new device is
3069				scanned for Logical Units (default 5).
3070	
3071		usb-storage.quirks=
3072				[UMS] A list of quirks entries to supplement or
3073				override the built-in unusual_devs list.  List
3074				entries are separated by commas.  Each entry has
3075				the form VID:PID:Flags where VID and PID are Vendor
3076				and Product ID values (4-digit hex numbers) and
3077				Flags is a set of characters, each corresponding
3078				to a common usb-storage quirk flag as follows:
3079					a = SANE_SENSE (collect more than 18 bytes
3080						of sense data);
3081					b = BAD_SENSE (don't collect more than 18
3082						bytes of sense data);
3083					c = FIX_CAPACITY (decrease the reported
3084						device capacity by one sector);
3085					d = NO_READ_DISC_INFO (don't use
3086						READ_DISC_INFO command);
3087					e = NO_READ_CAPACITY_16 (don't use
3088						READ_CAPACITY_16 command);
3089					h = CAPACITY_HEURISTICS (decrease the
3090						reported device capacity by one
3091						sector if the number is odd);
3092					i = IGNORE_DEVICE (don't bind to this
3093						device);
3094					l = NOT_LOCKABLE (don't try to lock and
3095						unlock ejectable media);
3096					m = MAX_SECTORS_64 (don't transfer more
3097						than 64 sectors = 32 KB at a time);
3098					n = INITIAL_READ10 (force a retry of the
3099						initial READ(10) command);
3100					o = CAPACITY_OK (accept the capacity
3101						reported by the device);
3102					p = WRITE_CACHE (the device cache is ON
3103						by default);
3104					r = IGNORE_RESIDUE (the device reports
3105						bogus residue values);
3106					s = SINGLE_LUN (the device has only one
3107						Logical Unit);
3108					w = NO_WP_DETECT (don't test whether the
3109						medium is write-protected).
3110				Example: quirks=0419:aaf5:rl,0421:0433:rc
3111	
3112		user_debug=	[KNL,ARM]
3113				Format: <int>
3114				See arch/arm/Kconfig.debug help text.
3115					 1 - undefined instruction events
3116					 2 - system calls
3117					 4 - invalid data aborts
3118					 8 - SIGSEGV faults
3119					16 - SIGBUS faults
3120				Example: user_debug=31
3121	
3122		userpte=
3123				[X86] Flags controlling user PTE allocations.
3124	
3125					nohigh = do not allocate PTE pages in
3126						HIGHMEM regardless of setting
3127						of CONFIG_HIGHPTE.
3128	
3129		vdso=		[X86,SH]
3130				vdso=2: enable compat VDSO (default with COMPAT_VDSO)
3131				vdso=1: enable VDSO (default)
3132				vdso=0: disable VDSO mapping
3133	
3134		vdso32=		[X86]
3135				vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
3136				vdso32=1: enable 32-bit VDSO (default)
3137				vdso32=0: disable 32-bit VDSO mapping
3138	
3139		vector=		[IA-64,SMP]
3140				vector=percpu: enable percpu vector domain
3141	
3142		video=		[FB] Frame buffer configuration
3143				See Documentation/fb/modedb.txt.
3144	
3145		virtio_mmio.device=
3146				[VMMIO] Memory mapped virtio (platform) device.
3147	
3148					<size>@<baseaddr>:<irq>[:<id>]
3149				where:
3150					<size>     := size (can use standard suffixes
3151							like K, M and G)
3152					<baseaddr> := physical base address
3153					<irq>      := interrupt number (as passed to
3154							request_irq())
3155					<id>       := (optional) platform device id
3156				example:
3157					virtio_mmio.device=1K@0x100b0000:48:7
3158	
3159				Can be used multiple times for multiple devices.
3160	
3161		vga=		[BOOT,X86-32] Select a particular video mode
3162				See Documentation/x86/boot.txt and
3163				Documentation/svga.txt.
3164				Use vga=ask for menu.
3165				This is actually a boot loader parameter; the value is
3166				passed to the kernel using a special protocol.
3167	
3168		vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
3169				size of <nn>. This can be used to increase the
3170				minimum size (128MB on x86). It can also be used to
3171				decrease the size and leave more room for directly
3172				mapped kernel RAM.
3173	
3174		vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
3175				Format: <command>
3176	
3177		vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
3178				Format: <command>
3179	
3180		vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
3181				Format: <command>
3182	
3183		vsyscall=	[X86-64]
3184				Controls the behavior of vsyscalls (i.e. calls to
3185				fixed addresses of 0xffffffffff600x00 from legacy
3186				code).  Most statically-linked binaries and older
3187				versions of glibc use these calls.  Because these
3188				functions are at fixed addresses, they make nice
3189				targets for exploits that can control RIP.
3190	
3191				emulate     [default] Vsyscalls turn into traps and are
3192				            emulated reasonably safely.
3193	
3194				native      Vsyscalls are native syscall instructions.
3195				            This is a little bit faster than trapping
3196				            and makes a few dynamic recompilers work
3197				            better than they would in emulation mode.
3198				            It also makes exploits much easier to write.
3199	
3200				none        Vsyscalls don't work at all.  This makes
3201				            them quite hard to use for exploits but
3202				            might break your system.
3203	
3204		vt.cur_default=	[VT] Default cursor shape.
3205				Format: 0xCCBBAA, where AA, BB, and CC are the same as
3206				the parameters of the <Esc>[?A;B;Cc escape sequence;
3207				see VGA-softcursor.txt. Default: 2 = underline.
3208	
3209		vt.default_blu=	[VT]
3210				Format: <blue0>,<blue1>,<blue2>,...,<blue15>
3211				Change the default blue palette of the console.
3212				This is a 16-member array composed of values
3213				ranging from 0-255.
3214	
3215		vt.default_grn=	[VT]
3216				Format: <green0>,<green1>,<green2>,...,<green15>
3217				Change the default green palette of the console.
3218				This is a 16-member array composed of values
3219				ranging from 0-255.
3220	
3221		vt.default_red=	[VT]
3222				Format: <red0>,<red1>,<red2>,...,<red15>
3223				Change the default red palette of the console.
3224				This is a 16-member array composed of values
3225				ranging from 0-255.
3226	
3227		vt.default_utf8=
3228				[VT]
3229				Format=<0|1>
3230				Set system-wide default UTF-8 mode for all tty's.
3231				Default is 1, i.e. UTF-8 mode is enabled for all
3232				newly opened terminals.
3233	
3234		vt.global_cursor_default=
3235				[VT]
3236				Format=<-1|0|1>
3237				Set system-wide default for whether a cursor
3238				is shown on new VTs. Default is -1,
3239				i.e. cursors will be created by default unless
3240				overridden by individual drivers. 0 will hide
3241				cursors, 1 will display them.
3242	
3243		watchdog timers	[HW,WDT] For information on watchdog timers,
3244				see Documentation/watchdog/watchdog-parameters.txt
3245				or other driver-specific files in the
3246				Documentation/watchdog/ directory.
3247	
3248		x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
3249				default x2apic cluster mode on platforms
3250				supporting x2apic.
3251	
3252		x86_mrst_timer= [X86-32,APBT]
3253				Choose timer option for x86 Moorestown MID platform.
3254				Two valid options are apbt timer only and lapic timer
3255				plus one apbt timer for broadcast timer.
3256				x86_mrst_timer=apbt_only | lapic_and_apbt
3257	
3258		xd=		[HW,XT] Original XT pre-IDE (RLL encoded) disks.
3259		xd_geo=		See header of drivers/block/xd.c.
3260	
3261		xen_emul_unplug=		[HW,X86,XEN]
3262				Unplug Xen emulated devices
3263				Format: [unplug0,][unplug1]
3264				ide-disks -- unplug primary master IDE devices
3265				aux-ide-disks -- unplug non-primary-master IDE devices
3266				nics -- unplug network devices
3267				all -- unplug all emulated devices (NICs and IDE disks)
3268				unnecessary -- unplugging emulated devices is
3269					unnecessary even if the host did not respond to
3270					the unplug protocol
3271				never -- do not unplug even if version check succeeds
3272	
3273		xirc2ps_cs=	[NET,PCMCIA]
3274				Format:
3275				<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
3276	
3277	______________________________________________________________________
3278	
3279	TODO:
3280	
3281		Add more DRM drivers.
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