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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:03 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		CLK	Common clock infrastructure is enabled.
48		CMA	Contiguous Memory Area support is enabled.
49		DRM	Direct Rendering Management support is enabled.
50		DYNAMIC_DEBUG Build in debug messages and enable them at runtime
51		EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled
52		EFI	EFI Partitioning (GPT) is enabled
53		EIDE	EIDE/ATAPI support is enabled.
54		EVM	Extended Verification Module
55		FB	The frame buffer device is enabled.
56		FTRACE	Function tracing enabled.
57		GCOV	GCOV profiling is enabled.
58		HW	Appropriate hardware is enabled.
59		IA-64	IA-64 architecture is enabled.
60		IMA     Integrity measurement architecture is enabled.
61		IOSCHED	More than one I/O scheduler is enabled.
62		IP_PNP	IP DHCP, BOOTP, or RARP is enabled.
63		IPV6	IPv6 support is enabled.
64		ISAPNP	ISA PnP code is enabled.
65		ISDN	Appropriate ISDN support is enabled.
66		JOY	Appropriate joystick support is enabled.
67		KGDB	Kernel debugger support is enabled.
68		KVM	Kernel Virtual Machine support is enabled.
69		LIBATA  Libata driver is enabled
70		LP	Printer support is enabled.
71		LOOP	Loopback device support is enabled.
72		M68k	M68k architecture is enabled.
73				These options have more detailed description inside of
74				Documentation/m68k/kernel-options.txt.
75		MDA	MDA console support is enabled.
76		MIPS	MIPS architecture is enabled.
77		MOUSE	Appropriate mouse support is enabled.
78		MSI	Message Signaled Interrupts (PCI).
79		MTD	MTD (Memory Technology Device) support is enabled.
80		NET	Appropriate network support is enabled.
81		NUMA	NUMA support is enabled.
82		NFS	Appropriate NFS support is enabled.
83		OSS	OSS sound support is enabled.
84		PV_OPS	A paravirtualized kernel is enabled.
85		PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.
86		PARISC	The PA-RISC architecture is enabled.
87		PCI	PCI bus support is enabled.
88		PCIE	PCI Express support is enabled.
89		PCMCIA	The PCMCIA subsystem is enabled.
90		PNP	Plug & Play support is enabled.
91		PPC	PowerPC architecture is enabled.
92		PPT	Parallel port support is enabled.
93		PS2	Appropriate PS/2 support is enabled.
94		RAM	RAM disk support is enabled.
95		S390	S390 architecture is enabled.
96		SCSI	Appropriate SCSI support is enabled.
97				A lot of drivers have their options described inside
98				the Documentation/scsi/ sub-directory.
99		SECURITY Different security models are enabled.
100		SELINUX SELinux support is enabled.
101		APPARMOR AppArmor support is enabled.
102		SERIAL	Serial support is enabled.
103		SH	SuperH architecture is enabled.
104		SMP	The kernel is an SMP kernel.
105		SPARC	Sparc architecture is enabled.
106		SWSUSP	Software suspend (hibernation) is enabled.
107		SUSPEND	System suspend states are enabled.
108		TPM	TPM drivers are enabled.
109		TS	Appropriate touchscreen support is enabled.
110		UMS	USB Mass Storage support is enabled.
111		USB	USB support is enabled.
112		USBHID	USB Human Interface Device support is enabled.
113		V4L	Video For Linux support is enabled.
114		VMMIO   Driver for memory mapped virtio devices is enabled.
115		VGA	The VGA console has been enabled.
116		VT	Virtual terminal support is enabled.
117		WDT	Watchdog support is enabled.
118		XT	IBM PC/XT MFM hard disk support is enabled.
119		X86-32	X86-32, aka i386 architecture is enabled.
120		X86-64	X86-64 architecture is enabled.
121				More X86-64 boot options can be found in
122				Documentation/x86/x86_64/boot-options.txt .
123		X86	Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
124		XEN	Xen support is enabled
125	
126	In addition, the following text indicates that the option:
127	
128		BUGS=	Relates to possible processor bugs on the said processor.
129		KNL	Is a kernel start-up parameter.
130		BOOT	Is a boot loader parameter.
131	
132	Parameters denoted with BOOT are actually interpreted by the boot
133	loader, and have no meaning to the kernel directly.
134	Do not modify the syntax of boot loader parameters without extreme
135	need or coordination with <Documentation/x86/boot.txt>.
136	
137	There are also arch-specific kernel-parameters not documented here.
138	See for example <Documentation/x86/x86_64/boot-options.txt>.
139	
140	Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
141	a trailing = on the name of any parameter states that that parameter will
142	be entered as an environment variable, whereas its absence indicates that
143	it will appear as a kernel argument readable via /proc/cmdline by programs
144	running once the system is up.
145	
146	The number of kernel parameters is not limited, but the length of the
147	complete command line (parameters including spaces etc.) is limited to
148	a fixed number of characters. This limit depends on the architecture
149	and is between 256 and 4096 characters. It is defined in the file
150	./include/asm/setup.h as COMMAND_LINE_SIZE.
151	
152	Finally, the [KMG] suffix is commonly described after a number of kernel
153	parameter values. These 'K', 'M', and 'G' letters represent the _binary_
154	multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
155	bytes respectively. Such letter suffixes can also be entirely omitted.
156	
157	
158		acpi=		[HW,ACPI,X86]
159				Advanced Configuration and Power Interface
160				Format: { force | off | strict | noirq | rsdt }
161				force -- enable ACPI if default was off
162				off -- disable ACPI if default was on
163				noirq -- do not use ACPI for IRQ routing
164				strict -- Be less tolerant of platforms that are not
165					strictly ACPI specification compliant.
166				rsdt -- prefer RSDT over (default) XSDT
167				copy_dsdt -- copy DSDT to memory
168	
169				See also Documentation/power/runtime_pm.txt, pci=noacpi
170	
171		acpi_rsdp=	[ACPI,EFI,KEXEC]
172				Pass the RSDP address to the kernel, mostly used
173				on machines running EFI runtime service to boot the
174				second kernel for kdump.
175	
176		acpi_apic_instance=	[ACPI, IOAPIC]
177				Format: <int>
178				2: use 2nd APIC table, if available
179				1,0: use 1st APIC table
180				default: 0
181	
182		acpi_backlight=	[HW,ACPI]
183				acpi_backlight=vendor
184				acpi_backlight=video
185				If set to vendor, prefer vendor specific driver
186				(e.g. thinkpad_acpi, sony_acpi, etc.) instead
187				of the ACPI video.ko driver.
188	
189		acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
190		acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
191				Format: <int>
192				CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
193				debug output.  Bits in debug_layer correspond to a
194				_COMPONENT in an ACPI source file, e.g.,
195				    #define _COMPONENT ACPI_PCI_COMPONENT
196				Bits in debug_level correspond to a level in
197				ACPI_DEBUG_PRINT statements, e.g.,
198				    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
199				The debug_level mask defaults to "info".  See
200				Documentation/acpi/debug.txt for more information about
201				debug layers and levels.
202	
203				Enable processor driver info messages:
204				    acpi.debug_layer=0x20000000
205				Enable PCI/PCI interrupt routing info messages:
206				    acpi.debug_layer=0x400000
207				Enable AML "Debug" output, i.e., stores to the Debug
208				object while interpreting AML:
209				    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
210				Enable all messages related to ACPI hardware:
211				    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
212	
213				Some values produce so much output that the system is
214				unusable.  The "log_buf_len" parameter may be useful
215				if you need to capture more output.
216	
217		acpi_irq_balance [HW,ACPI]
218				ACPI will balance active IRQs
219				default in APIC mode
220	
221		acpi_irq_nobalance [HW,ACPI]
222				ACPI will not move active IRQs (default)
223				default in PIC mode
224	
225		acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
226				Format: <irq>,<irq>...
227	
228		acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
229				use by PCI
230				Format: <irq>,<irq>...
231	
232		acpi_no_auto_serialize	[HW,ACPI]
233				Disable auto-serialization of AML methods
234				AML control methods that contain the opcodes to create
235				named objects will be marked as "Serialized" by the
236				auto-serialization feature.
237				This feature is enabled by default.
238				This option allows to turn off the feature.
239	
240		acpi_no_auto_ssdt	[HW,ACPI] Disable automatic loading of SSDT
241	
242		acpica_no_return_repair [HW, ACPI]
243				Disable AML predefined validation mechanism
244				This mechanism can repair the evaluation result to make
245				the return objects more ACPI specification compliant.
246				This option is useful for developers to identify the
247				root cause of an AML interpreter issue when the issue
248				has something to do with the repair mechanism.
249	
250		acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
251				Format: To spoof as Windows 98: ="Microsoft Windows"
252	
253		acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
254				acpi_osi="string1"	# add string1
255				acpi_osi="!string2"	# remove string2
256				acpi_osi=!*		# remove all strings
257				acpi_osi=!		# disable all built-in OS vendor
258							  strings
259				acpi_osi=		# disable all strings
260	
261				'acpi_osi=!' can be used in combination with single or
262				multiple 'acpi_osi="string1"' to support specific OS
263				vendor string(s).  Note that such command can only
264				affect the default state of the OS vendor strings, thus
265				it cannot affect the default state of the feature group
266				strings and the current state of the OS vendor strings,
267				specifying it multiple times through kernel command line
268				is meaningless.  This command is useful when one do not
269				care about the state of the feature group strings which
270				should be controlled by the OSPM.
271				Examples:
272				  1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
273				     to 'acpi_osi="Windows 2000" acpi_osi=!', they all
274				     can make '_OSI("Windows 2000")' TRUE.
275	
276				'acpi_osi=' cannot be used in combination with other
277				'acpi_osi=' command lines, the _OSI method will not
278				exist in the ACPI namespace.  NOTE that such command can
279				only affect the _OSI support state, thus specifying it
280				multiple times through kernel command line is also
281				meaningless.
282				Examples:
283				  1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
284				     FALSE.
285	
286				'acpi_osi=!*' can be used in combination with single or
287				multiple 'acpi_osi="string1"' to support specific
288				string(s).  Note that such command can affect the
289				current state of both the OS vendor strings and the
290				feature group strings, thus specifying it multiple times
291				through kernel command line is meaningful.  But it may
292				still not able to affect the final state of a string if
293				there are quirks related to this string.  This command
294				is useful when one want to control the state of the
295				feature group strings to debug BIOS issues related to
296				the OSPM features.
297				Examples:
298				  1. 'acpi_osi="Module Device" acpi_osi=!*' can make
299				     '_OSI("Module Device")' FALSE.
300				  2. 'acpi_osi=!* acpi_osi="Module Device"' can make
301				     '_OSI("Module Device")' TRUE.
302				  3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
303				     equivalent to
304				     'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
305				     and
306				     'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
307				     they all will make '_OSI("Windows 2000")' TRUE.
308	
309		acpi_pm_good	[X86]
310				Override the pmtimer bug detection: force the kernel
311				to assume that this machine's pmtimer latches its value
312				and always returns good values.
313	
314		acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
315				Format: { level | edge | high | low }
316	
317		acpi_skip_timer_override [HW,ACPI]
318				Recognize and ignore IRQ0/pin2 Interrupt Override.
319				For broken nForce2 BIOS resulting in XT-PIC timer.
320	
321		acpi_sleep=	[HW,ACPI] Sleep options
322				Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
323					  old_ordering, nonvs, sci_force_enable }
324				See Documentation/power/video.txt for information on
325				s3_bios and s3_mode.
326				s3_beep is for debugging; it makes the PC's speaker beep
327				as soon as the kernel's real-mode entry point is called.
328				s4_nohwsig prevents ACPI hardware signature from being
329				used during resume from hibernation.
330				old_ordering causes the ACPI 1.0 ordering of the _PTS
331				control method, with respect to putting devices into
332				low power states, to be enforced (the ACPI 2.0 ordering
333				of _PTS is used by default).
334				nonvs prevents the kernel from saving/restoring the
335				ACPI NVS memory during suspend/hibernation and resume.
336				sci_force_enable causes the kernel to set SCI_EN directly
337				on resume from S1/S3 (which is against the ACPI spec,
338				but some broken systems don't work without it).
339	
340		acpi_use_timer_override [HW,ACPI]
341				Use timer override. For some broken Nvidia NF5 boards
342				that require a timer override, but don't have HPET
343	
344		acpi_enforce_resources=	[ACPI]
345				{ strict | lax | no }
346				Check for resource conflicts between native drivers
347				and ACPI OperationRegions (SystemIO and SystemMemory
348				only). IO ports and memory declared in ACPI might be
349				used by the ACPI subsystem in arbitrary AML code and
350				can interfere with legacy drivers.
351				strict (default): access to resources claimed by ACPI
352				is denied; legacy drivers trying to access reserved
353				resources will fail to bind to device using them.
354				lax: access to resources claimed by ACPI is allowed;
355				legacy drivers trying to access reserved resources
356				will bind successfully but a warning message is logged.
357				no: ACPI OperationRegions are not marked as reserved,
358				no further checks are performed.
359	
360		acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kdump
361				   kernels.
362	
363		add_efi_memmap	[EFI; X86] Include EFI memory map in
364				kernel's map of available physical RAM.
365	
366		agp=		[AGP]
367				{ off | try_unsupported }
368				off: disable AGP support
369				try_unsupported: try to drive unsupported chipsets
370					(may crash computer or cause data corruption)
371	
372		ALSA		[HW,ALSA]
373				See Documentation/sound/alsa/alsa-parameters.txt
374	
375		alignment=	[KNL,ARM]
376				Allow the default userspace alignment fault handler
377				behaviour to be specified.  Bit 0 enables warnings,
378				bit 1 enables fixups, and bit 2 sends a segfault.
379	
380		align_va_addr=	[X86-64]
381				Align virtual addresses by clearing slice [14:12] when
382				allocating a VMA at process creation time. This option
383				gives you up to 3% performance improvement on AMD F15h
384				machines (where it is enabled by default) for a
385				CPU-intensive style benchmark, and it can vary highly in
386				a microbenchmark depending on workload and compiler.
387	
388				32: only for 32-bit processes
389				64: only for 64-bit processes
390				on: enable for both 32- and 64-bit processes
391				off: disable for both 32- and 64-bit processes
392	
393		alloc_snapshot	[FTRACE]
394				Allocate the ftrace snapshot buffer on boot up when the
395				main buffer is allocated. This is handy if debugging
396				and you need to use tracing_snapshot() on boot up, and
397				do not want to use tracing_snapshot_alloc() as it needs
398				to be done where GFP_KERNEL allocations are allowed.
399	
400		amd_iommu=	[HW,X86-64]
401				Pass parameters to the AMD IOMMU driver in the system.
402				Possible values are:
403				fullflush - enable flushing of IO/TLB entries when
404					    they are unmapped. Otherwise they are
405					    flushed before they will be reused, which
406					    is a lot of faster
407				off	  - do not initialize any AMD IOMMU found in
408					    the system
409				force_isolation - Force device isolation for all
410						  devices. The IOMMU driver is not
411						  allowed anymore to lift isolation
412						  requirements as needed. This option
413						  does not override iommu=pt
414	
415		amd_iommu_dump=	[HW,X86-64]
416				Enable AMD IOMMU driver option to dump the ACPI table
417				for AMD IOMMU. With this option enabled, AMD IOMMU
418				driver will print ACPI tables for AMD IOMMU during
419				IOMMU initialization.
420	
421		amijoy.map=	[HW,JOY] Amiga joystick support
422				Map of devices attached to JOY0DAT and JOY1DAT
423				Format: <a>,<b>
424				See also Documentation/input/joystick.txt
425	
426		analog.map=	[HW,JOY] Analog joystick and gamepad support
427				Specifies type or capabilities of an analog joystick
428				connected to one of 16 gameports
429				Format: <type1>,<type2>,..<type16>
430	
431		apc=		[HW,SPARC]
432				Power management functions (SPARCstation-4/5 + deriv.)
433				Format: noidle
434				Disable APC CPU standby support. SPARCstation-Fox does
435				not play well with APC CPU idle - disable it if you have
436				APC and your system crashes randomly.
437	
438		apic=		[APIC,X86-32] Advanced Programmable Interrupt Controller
439				Change the output verbosity whilst booting
440				Format: { quiet (default) | verbose | debug }
441				Change the amount of debugging information output
442				when initialising the APIC and IO-APIC components.
443	
444		autoconf=	[IPV6]
445				See Documentation/networking/ipv6.txt.
446	
447		show_lapic=	[APIC,X86] Advanced Programmable Interrupt Controller
448				Limit apic dumping. The parameter defines the maximal
449				number of local apics being dumped. Also it is possible
450				to set it to "all" by meaning -- no limit here.
451				Format: { 1 (default) | 2 | ... | all }.
452				The parameter valid if only apic=debug or
453				apic=verbose is specified.
454				Example: apic=debug show_lapic=all
455	
456		apm=		[APM] Advanced Power Management
457				See header of arch/x86/kernel/apm_32.c.
458	
459		arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
460				Format: <io>,<irq>,<nodeID>
461	
462		ataflop=	[HW,M68k]
463	
464		atarimouse=	[HW,MOUSE] Atari Mouse
465	
466		atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
467				EzKey and similar keyboards
468	
469		atkbd.reset=	[HW] Reset keyboard during initialization
470	
471		atkbd.set=	[HW] Select keyboard code set
472				Format: <int> (2 = AT (default), 3 = PS/2)
473	
474		atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
475				keyboards
476	
477		atkbd.softraw=	[HW] Choose between synthetic and real raw mode
478				Format: <bool> (0 = real, 1 = synthetic (default))
479	
480		atkbd.softrepeat= [HW]
481				Use software keyboard repeat
482	
483		audit=		[KNL] Enable the audit sub-system
484				Format: { "0" | "1" } (0 = disabled, 1 = enabled)
485				0 - kernel audit is disabled and can not be enabled
486				    until the next reboot
487				unset - kernel audit is initialized but disabled and
488				    will be fully enabled by the userspace auditd.
489				1 - kernel audit is initialized and partially enabled,
490				    storing at most audit_backlog_limit messages in
491				    RAM until it is fully enabled by the userspace
492				    auditd.
493				Default: unset
494	
495		audit_backlog_limit= [KNL] Set the audit queue size limit.
496				Format: <int> (must be >=0)
497				Default: 64
498	
499		baycom_epp=	[HW,AX25]
500				Format: <io>,<mode>
501	
502		baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
503				Format: <io>,<mode>
504				See header of drivers/net/hamradio/baycom_par.c.
505	
506		baycom_ser_fdx=	[HW,AX25]
507				BayCom Serial Port AX.25 Modem (Full Duplex Mode)
508				Format: <io>,<irq>,<mode>[,<baud>]
509				See header of drivers/net/hamradio/baycom_ser_fdx.c.
510	
511		baycom_ser_hdx=	[HW,AX25]
512				BayCom Serial Port AX.25 Modem (Half Duplex Mode)
513				Format: <io>,<irq>,<mode>
514				See header of drivers/net/hamradio/baycom_ser_hdx.c.
515	
516		blkdevparts=	Manual partition parsing of block device(s) for
517				embedded devices based on command line input.
518				See Documentation/block/cmdline-partition.txt
519	
520		boot_delay=	Milliseconds to delay each printk during boot.
521				Values larger than 10 seconds (10000) are changed to
522				no delay (0).
523				Format: integer
524	
525		bootmem_debug	[KNL] Enable bootmem allocator debug messages.
526	
527		bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
528		bttv.radio=	Most important insmod options are available as
529				kernel args too.
530		bttv.pll=	See Documentation/video4linux/bttv/Insmod-options
531		bttv.tuner=
532	
533		bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
534				firmware feature for flushing multiple hpte entries
535				at a time.
536	
537		c101=		[NET] Moxa C101 synchronous serial card
538	
539		cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
540				Sometimes CPU hardware bugs make them report the cache
541				size incorrectly. The kernel will attempt work arounds
542				to fix known problems, but for some CPUs it is not
543				possible to determine what the correct size should be.
544				This option provides an override for these situations.
545	
546		ccw_timeout_log [S390]
547				See Documentation/s390/CommonIO for details.
548	
549		cgroup_disable= [KNL] Disable a particular controller
550				Format: {name of the controller(s) to disable}
551				The effects of cgroup_disable=foo are:
552				- foo isn't auto-mounted if you mount all cgroups in
553				  a single hierarchy
554				- foo isn't visible as an individually mountable
555				  subsystem
556				{Currently only "memory" controller deal with this and
557				cut the overhead, others just disable the usage. So
558				only cgroup_disable=memory is actually worthy}
559	
560		checkreqprot	[SELINUX] Set initial checkreqprot flag value.
561				Format: { "0" | "1" }
562				See security/selinux/Kconfig help text.
563				0 -- check protection applied by kernel (includes
564					any implied execute protection).
565				1 -- check protection requested by application.
566				Default value is set via a kernel config option.
567				Value can be changed at runtime via
568					/selinux/checkreqprot.
569	
570		cio_ignore=	[S390]
571				See Documentation/s390/CommonIO for details.
572		clk_ignore_unused
573				[CLK]
574				Keep all clocks already enabled by bootloader on,
575				even if no driver has claimed them. This is useful
576				for debug and development, but should not be
577				needed on a platform with proper driver support.
578				For more information, see Documentation/clk.txt.
579	
580		clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
581				[Deprecated]
582				Forces specified clocksource (if available) to be used
583				when calculating gettimeofday(). If specified
584				clocksource is not available, it defaults to PIT.
585				Format: { pit | tsc | cyclone | pmtmr }
586	
587		clocksource=	Override the default clocksource
588				Format: <string>
589				Override the default clocksource and use the clocksource
590				with the name specified.
591				Some clocksource names to choose from, depending on
592				the platform:
593				[all] jiffies (this is the base, fallback clocksource)
594				[ACPI] acpi_pm
595				[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
596					pxa_timer,timer3,32k_counter,timer0_1
597				[AVR32] avr32
598				[X86-32] pit,hpet,tsc;
599					scx200_hrt on Geode; cyclone on IBM x440
600				[MIPS] MIPS
601				[PARISC] cr16
602				[S390] tod
603				[SH] SuperH
604				[SPARC64] tick
605				[X86-64] hpet,tsc
606	
607		clearcpuid=BITNUM [X86]
608				Disable CPUID feature X for the kernel. See
609				arch/x86/include/asm/cpufeature.h for the valid bit
610				numbers. Note the Linux specific bits are not necessarily
611				stable over kernel options, but the vendor specific
612				ones should be.
613				Also note that user programs calling CPUID directly
614				or using the feature without checking anything
615				will still see it. This just prevents it from
616				being used by the kernel or shown in /proc/cpuinfo.
617				Also note the kernel might malfunction if you disable
618				some critical bits.
619	
620		cma=nn[MG]	[ARM,KNL]
621				Sets the size of kernel global memory area for contiguous
622				memory allocations. For more information, see
623				include/linux/dma-contiguous.h
624	
625		cmo_free_hint=	[PPC] Format: { yes | no }
626				Specify whether pages are marked as being inactive
627				when they are freed.  This is used in CMO environments
628				to determine OS memory pressure for page stealing by
629				a hypervisor.
630				Default: yes
631	
632		coherent_pool=nn[KMG]	[ARM,KNL]
633				Sets the size of memory pool for coherent, atomic dma
634				allocations, by default set to 256K.
635	
636		code_bytes	[X86] How many bytes of object code to print
637				in an oops report.
638				Range: 0 - 8192
639				Default: 64
640	
641		com20020=	[HW,NET] ARCnet - COM20020 chipset
642				Format:
643				<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
644	
645		com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
646				Format: <io>[,<irq>]
647	
648		com90xx=	[HW,NET]
649				ARCnet - COM90xx chipset (memory-mapped buffers)
650				Format: <io>[,<irq>[,<memstart>]]
651	
652		condev=		[HW,S390] console device
653		conmode=
654	
655		console=	[KNL] Output console device and options.
656	
657			tty<n>	Use the virtual console device <n>.
658	
659			ttyS<n>[,options]
660			ttyUSB0[,options]
661				Use the specified serial port.  The options are of
662				the form "bbbbpnf", where "bbbb" is the baud rate,
663				"p" is parity ("n", "o", or "e"), "n" is number of
664				bits, and "f" is flow control ("r" for RTS or
665				omit it).  Default is "9600n8".
666	
667				See Documentation/serial-console.txt for more
668				information.  See
669				Documentation/networking/netconsole.txt for an
670				alternative.
671	
672			uart[8250],io,<addr>[,options]
673			uart[8250],mmio,<addr>[,options]
674				Start an early, polled-mode console on the 8250/16550
675				UART at the specified I/O port or MMIO address,
676				switching to the matching ttyS device later.  The
677				options are the same as for ttyS, above.
678			hvc<n>	Use the hypervisor console device <n>. This is for
679				both Xen and PowerPC hypervisors.
680	
681	                If the device connected to the port is not a TTY but a braille
682	                device, prepend "brl," before the device type, for instance
683				console=brl,ttyS0
684			For now, only VisioBraille is supported.
685	
686		consoleblank=	[KNL] The console blank (screen saver) timeout in
687				seconds. Defaults to 10*60 = 10mins. A value of 0
688				disables the blank timer.
689	
690		coredump_filter=
691				[KNL] Change the default value for
692				/proc/<pid>/coredump_filter.
693				See also Documentation/filesystems/proc.txt.
694	
695		cpuidle.off=1	[CPU_IDLE]
696				disable the cpuidle sub-system
697	
698		cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
699				Format:
700				<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
701	
702		crashkernel=size[KMG][@offset[KMG]]
703				[KNL] Using kexec, Linux can switch to a 'crash kernel'
704				upon panic. This parameter reserves the physical
705				memory region [offset, offset + size] for that kernel
706				image. If '@offset' is omitted, then a suitable offset
707				is selected automatically. Check
708				Documentation/kdump/kdump.txt for further details.
709	
710		crashkernel=range1:size1[,range2:size2,...][@offset]
711				[KNL] Same as above, but depends on the memory
712				in the running system. The syntax of range is
713				start-[end] where start and end are both
714				a memory unit (amount[KMG]). See also
715				Documentation/kdump/kdump.txt for an example.
716	
717		crashkernel=size[KMG],high
718				[KNL, x86_64] range could be above 4G. Allow kernel
719				to allocate physical memory region from top, so could
720				be above 4G if system have more than 4G ram installed.
721				Otherwise memory region will be allocated below 4G, if
722				available.
723				It will be ignored if crashkernel=X is specified.
724		crashkernel=size[KMG],low
725				[KNL, x86_64] range under 4G. When crashkernel=X,high
726				is passed, kernel could allocate physical memory region
727				above 4G, that cause second kernel crash on system
728				that require some amount of low memory, e.g. swiotlb
729				requires at least 64M+32K low memory.  Kernel would
730				try to allocate 72M below 4G automatically.
731				This one let user to specify own low range under 4G
732				for second kernel instead.
733				0: to disable low allocation.
734				It will be ignored when crashkernel=X,high is not used
735				or memory reserved is below 4G.
736	
737		cs89x0_dma=	[HW,NET]
738				Format: <dma>
739	
740		cs89x0_media=	[HW,NET]
741				Format: { rj45 | aui | bnc }
742	
743		dasd=		[HW,NET]
744				See header of drivers/s390/block/dasd_devmap.c.
745	
746		db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
747				(one device per port)
748				Format: <port#>,<type>
749				See also Documentation/input/joystick-parport.txt
750	
751		ddebug_query=   [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
752				time. See Documentation/dynamic-debug-howto.txt for
753				details.  Deprecated, see dyndbg.
754	
755		debug		[KNL] Enable kernel debugging (events log level).
756	
757		debug_locks_verbose=
758				[KNL] verbose self-tests
759				Format=<0|1>
760				Print debugging info while doing the locking API
761				self-tests.
762				We default to 0 (no extra messages), setting it to
763				1 will print _a lot_ more information - normally
764				only useful to kernel developers.
765	
766		debug_objects	[KNL] Enable object debugging
767	
768		no_debug_objects
769				[KNL] Disable object debugging
770	
771		debug_guardpage_minorder=
772				[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
773				parameter allows control of the order of pages that will
774				be intentionally kept free (and hence protected) by the
775				buddy allocator. Bigger value increase the probability
776				of catching random memory corruption, but reduce the
777				amount of memory for normal system use. The maximum
778				possible value is MAX_ORDER/2.  Setting this parameter
779				to 1 or 2 should be enough to identify most random
780				memory corruption problems caused by bugs in kernel or
781				driver code when a CPU writes to (or reads from) a
782				random memory location. Note that there exists a class
783				of memory corruptions problems caused by buggy H/W or
784				F/W or by drivers badly programing DMA (basically when
785				memory is written at bus level and the CPU MMU is
786				bypassed) which are not detectable by
787				CONFIG_DEBUG_PAGEALLOC, hence this option will not help
788				tracking down these problems.
789	
790		debugpat	[X86] Enable PAT debugging
791	
792		decnet.addr=	[HW,NET]
793				Format: <area>[,<node>]
794				See also Documentation/networking/decnet.txt.
795	
796		default_hugepagesz=
797				[same as hugepagesz=] The size of the default
798				HugeTLB page size. This is the size represented by
799				the legacy /proc/ hugepages APIs, used for SHM, and
800				default size when mounting hugetlbfs filesystems.
801				Defaults to the default architecture's huge page size
802				if not specified.
803	
804		dhash_entries=	[KNL]
805				Set number of hash buckets for dentry cache.
806	
807		disable=	[IPV6]
808				See Documentation/networking/ipv6.txt.
809	
810		disable_cpu_apicid= [X86,APIC,SMP]
811				Format: <int>
812				The number of initial APIC ID for the
813				corresponding CPU to be disabled at boot,
814				mostly used for the kdump 2nd kernel to
815				disable BSP to wake up multiple CPUs without
816				causing system reset or hang due to sending
817				INIT from AP to BSP.
818	
819		disable_ddw     [PPC/PSERIES]
820				Disable Dynamic DMA Window support. Use this if
821				to workaround buggy firmware.
822	
823		disable_ipv6=	[IPV6]
824				See Documentation/networking/ipv6.txt.
825	
826		disable_mtrr_cleanup [X86]
827				The kernel tries to adjust MTRR layout from continuous
828				to discrete, to make X server driver able to add WB
829				entry later. This parameter disables that.
830	
831		disable_mtrr_trim [X86, Intel and AMD only]
832				By default the kernel will trim any uncacheable
833				memory out of your available memory pool based on
834				MTRR settings.  This parameter disables that behavior,
835				possibly causing your machine to run very slowly.
836	
837		disable_timer_pin_1 [X86]
838				Disable PIN 1 of APIC timer
839				Can be useful to work around chipset bugs.
840	
841		dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
842				this option disables the debugging code at boot.
843	
844		dma_debug_entries=<number>
845				This option allows to tune the number of preallocated
846				entries for DMA-API debugging code. One entry is
847				required per DMA-API allocation. Use this if the
848				DMA-API debugging code disables itself because the
849				architectural default is too low.
850	
851		dma_debug_driver=<driver_name>
852				With this option the DMA-API debugging driver
853				filter feature can be enabled at boot time. Just
854				pass the driver to filter for as the parameter.
855				The filter can be disabled or changed to another
856				driver later using sysfs.
857	
858		drm_kms_helper.edid_firmware=[<connector>:]<file>
859				Broken monitors, graphic adapters and KVMs may
860				send no or incorrect EDID data sets. This parameter
861				allows to specify an EDID data set in the
862				/lib/firmware directory that is used instead.
863				Generic built-in EDID data sets are used, if one of
864				edid/1024x768.bin, edid/1280x1024.bin,
865				edid/1680x1050.bin, or edid/1920x1080.bin is given
866				and no file with the same name exists. Details and
867				instructions how to build your own EDID data are
868				available in Documentation/EDID/HOWTO.txt. An EDID
869				data set will only be used for a particular connector,
870				if its name and a colon are prepended to the EDID
871				name.
872	
873		dscc4.setup=	[NET]
874	
875		dyndbg[="val"]		[KNL,DYNAMIC_DEBUG]
876		module.dyndbg[="val"]
877				Enable debug messages at boot time.  See
878				Documentation/dynamic-debug-howto.txt for details.
879	
880		early_ioremap_debug [KNL]
881				Enable debug messages in early_ioremap support. This
882				is useful for tracking down temporary early mappings
883				which are not unmapped.
884	
885		earlycon=	[KNL] Output early console device and options.
886			uart[8250],io,<addr>[,options]
887			uart[8250],mmio,<addr>[,options]
888			uart[8250],mmio32,<addr>[,options]
889				Start an early, polled-mode console on the 8250/16550
890				UART at the specified I/O port or MMIO address.
891				MMIO inter-register address stride is either 8-bit
892				(mmio) or 32-bit (mmio32).
893				The options are the same as for ttyS, above.
894	
895		earlyprintk=	[X86,SH,BLACKFIN,ARM]
896				earlyprintk=vga
897				earlyprintk=efi
898				earlyprintk=xen
899				earlyprintk=serial[,ttySn[,baudrate]]
900				earlyprintk=serial[,0x...[,baudrate]]
901				earlyprintk=ttySn[,baudrate]
902				earlyprintk=dbgp[debugController#]
903	
904				earlyprintk is useful when the kernel crashes before
905				the normal console is initialized. It is not enabled by
906				default because it has some cosmetic problems.
907	
908				Append ",keep" to not disable it when the real console
909				takes over.
910	
911				Only one of vga, efi, serial, or usb debug port can
912				be used at a time.
913	
914				Currently only ttyS0 and ttyS1 may be specified by
915				name.  Other I/O ports may be explicitly specified
916				on some architectures (x86 and arm at least) by
917				replacing ttySn with an I/O port address, like this:
918					earlyprintk=serial,0x1008,115200
919				You can find the port for a given device in
920				/proc/tty/driver/serial:
921					2: uart:ST16650V2 port:00001008 irq:18 ...
922	
923				Interaction with the standard serial driver is not
924				very good.
925	
926				The VGA and EFI output is eventually overwritten by
927				the real console.
928	
929				The xen output can only be used by Xen PV guests.
930	
931		edac_report=	[HW,EDAC] Control how to report EDAC event
932				Format: {"on" | "off" | "force"}
933				on: enable EDAC to report H/W event. May be overridden
934				by other higher priority error reporting module.
935				off: disable H/W event reporting through EDAC.
936				force: enforce the use of EDAC to report H/W event.
937				default: on.
938	
939		ekgdboc=	[X86,KGDB] Allow early kernel console debugging
940				ekgdboc=kbd
941	
942				This is designed to be used in conjunction with
943				the boot argument: earlyprintk=vga
944	
945		edd=		[EDD]
946				Format: {"off" | "on" | "skip[mbr]"}
947	
948		efi=		[EFI]
949				Format: { "old_map" }
950				old_map [X86-64]: switch to the old ioremap-based EFI
951				runtime services mapping. 32-bit still uses this one by
952				default.
953	
954		efi_no_storage_paranoia [EFI; X86]
955				Using this parameter you can use more than 50% of
956				your efi variable storage. Use this parameter only if
957				you are really sure that your UEFI does sane gc and
958				fulfills the spec otherwise your board may brick.
959	
960		eisa_irq_edge=	[PARISC,HW]
961				See header of drivers/parisc/eisa.c.
962	
963		elanfreq=	[X86-32]
964				See comment before function elanfreq_setup() in
965				arch/x86/kernel/cpu/cpufreq/elanfreq.c.
966	
967		elevator=	[IOSCHED]
968				Format: {"cfq" | "deadline" | "noop"}
969				See Documentation/block/cfq-iosched.txt and
970				Documentation/block/deadline-iosched.txt for details.
971	
972		elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
973				Specifies physical address of start of kernel core
974				image elf header and optionally the size. Generally
975				kexec loader will pass this option to capture kernel.
976				See Documentation/kdump/kdump.txt for details.
977	
978		enable_mtrr_cleanup [X86]
979				The kernel tries to adjust MTRR layout from continuous
980				to discrete, to make X server driver able to add WB
981				entry later. This parameter enables that.
982	
983		enable_timer_pin_1 [X86]
984				Enable PIN 1 of APIC timer
985				Can be useful to work around chipset bugs
986				(in particular on some ATI chipsets).
987				The kernel tries to set a reasonable default.
988	
989		enforcing	[SELINUX] Set initial enforcing status.
990				Format: {"0" | "1"}
991				See security/selinux/Kconfig help text.
992				0 -- permissive (log only, no denials).
993				1 -- enforcing (deny and log).
994				Default value is 0.
995				Value can be changed at runtime via /selinux/enforce.
996	
997		erst_disable	[ACPI]
998				Disable Error Record Serialization Table (ERST)
999				support.
1000	
1001		ether=		[HW,NET] Ethernet cards parameters
1002				This option is obsoleted by the "netdev=" option, which
1003				has equivalent usage. See its documentation for details.
1004	
1005		evm=		[EVM]
1006				Format: { "fix" }
1007				Permit 'security.evm' to be updated regardless of
1008				current integrity status.
1009	
1010		failslab=
1011		fail_page_alloc=
1012		fail_make_request=[KNL]
1013				General fault injection mechanism.
1014				Format: <interval>,<probability>,<space>,<times>
1015				See also Documentation/fault-injection/.
1016	
1017		floppy=		[HW]
1018				See Documentation/blockdev/floppy.txt.
1019	
1020		force_pal_cache_flush
1021				[IA-64] Avoid check_sal_cache_flush which may hang on
1022				buggy SAL_CACHE_FLUSH implementations. Using this
1023				parameter will force ia64_sal_cache_flush to call
1024				ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
1025	
1026		forcepae [X86-32]
1027				Forcefully enable Physical Address Extension (PAE).
1028				Many Pentium M systems disable PAE but may have a
1029				functionally usable PAE implementation.
1030				Warning: use of this parameter will taint the kernel
1031				and may cause unknown problems.
1032	
1033		ftrace=[tracer]
1034				[FTRACE] will set and start the specified tracer
1035				as early as possible in order to facilitate early
1036				boot debugging.
1037	
1038		ftrace_dump_on_oops[=orig_cpu]
1039				[FTRACE] will dump the trace buffers on oops.
1040				If no parameter is passed, ftrace will dump
1041				buffers of all CPUs, but if you pass orig_cpu, it will
1042				dump only the buffer of the CPU that triggered the
1043				oops.
1044	
1045		ftrace_filter=[function-list]
1046				[FTRACE] Limit the functions traced by the function
1047				tracer at boot up. function-list is a comma separated
1048				list of functions. This list can be changed at run
1049				time by the set_ftrace_filter file in the debugfs
1050				tracing directory.
1051	
1052		ftrace_notrace=[function-list]
1053				[FTRACE] Do not trace the functions specified in
1054				function-list. This list can be changed at run time
1055				by the set_ftrace_notrace file in the debugfs
1056				tracing directory.
1057	
1058		ftrace_graph_filter=[function-list]
1059				[FTRACE] Limit the top level callers functions traced
1060				by the function graph tracer at boot up.
1061				function-list is a comma separated list of functions
1062				that can be changed at run time by the
1063				set_graph_function file in the debugfs tracing directory.
1064	
1065		gamecon.map[2|3]=
1066				[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
1067				support via parallel port (up to 5 devices per port)
1068				Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1069				See also Documentation/input/joystick-parport.txt
1070	
1071		gamma=		[HW,DRM]
1072	
1073		gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
1074				Format: off | on
1075				default: on
1076	
1077		gcov_persist=	[GCOV] When non-zero (default), profiling data for
1078				kernel modules is saved and remains accessible via
1079				debugfs, even when the module is unloaded/reloaded.
1080				When zero, profiling data is discarded and associated
1081				debugfs files are removed at module unload time.
1082	
1083		gpt		[EFI] Forces disk with valid GPT signature but
1084				invalid Protective MBR to be treated as GPT. If the
1085				primary GPT is corrupted, it enables the backup/alternate
1086				GPT to be used instead.
1087	
1088		grcan.enable0=	[HW] Configuration of physical interface 0. Determines
1089				the "Enable 0" bit of the configuration register.
1090				Format: 0 | 1
1091				Default: 0
1092		grcan.enable1=	[HW] Configuration of physical interface 1. Determines
1093				the "Enable 0" bit of the configuration register.
1094				Format: 0 | 1
1095				Default: 0
1096		grcan.select=	[HW] Select which physical interface to use.
1097				Format: 0 | 1
1098				Default: 0
1099		grcan.txsize=	[HW] Sets the size of the tx buffer.
1100				Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
1101				Default: 1024
1102		grcan.rxsize=	[HW] Sets the size of the rx buffer.
1103				Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
1104				Default: 1024
1105	
1106		hashdist=	[KNL,NUMA] Large hashes allocated during boot
1107				are distributed across NUMA nodes.  Defaults on
1108				for 64-bit NUMA, off otherwise.
1109				Format: 0 | 1 (for off | on)
1110	
1111		hcl=		[IA-64] SGI's Hardware Graph compatibility layer
1112	
1113		hd=		[EIDE] (E)IDE hard drive subsystem geometry
1114				Format: <cyl>,<head>,<sect>
1115	
1116		hest_disable	[ACPI]
1117				Disable Hardware Error Source Table (HEST) support;
1118				corresponding firmware-first mode error processing
1119				logic will be disabled.
1120	
1121		highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
1122				size of <nn>. This works even on boxes that have no
1123				highmem otherwise. This also works to reduce highmem
1124				size on bigger boxes.
1125	
1126		highres=	[KNL] Enable/disable high resolution timer mode.
1127				Valid parameters: "on", "off"
1128				Default: "on"
1129	
1130		hisax=		[HW,ISDN]
1131				See Documentation/isdn/README.HiSax.
1132	
1133		hlt		[BUGS=ARM,SH]
1134	
1135		hpet=		[X86-32,HPET] option to control HPET usage
1136				Format: { enable (default) | disable | force |
1137					verbose }
1138				disable: disable HPET and use PIT instead
1139				force: allow force enabled of undocumented chips (ICH4,
1140					VIA, nVidia)
1141				verbose: show contents of HPET registers during setup
1142	
1143		hpet_mmap=	[X86, HPET_MMAP] Allow userspace to mmap HPET
1144				registers.  Default set by CONFIG_HPET_MMAP_DEFAULT.
1145	
1146		hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
1147		hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
1148				On x86-64 and powerpc, this option can be specified
1149				multiple times interleaved with hugepages= to reserve
1150				huge pages of different sizes. Valid pages sizes on
1151				x86-64 are 2M (when the CPU supports "pse") and 1G
1152				(when the CPU supports the "pdpe1gb" cpuinfo flag)
1153				Note that 1GB pages can only be allocated at boot time
1154				using hugepages= and not freed afterwards.
1155	
1156		hvc_iucv=	[S390] Number of z/VM IUCV hypervisor console (HVC)
1157				       terminal devices. Valid values: 0..8
1158		hvc_iucv_allow=	[S390] Comma-separated list of z/VM user IDs.
1159				       If specified, z/VM IUCV HVC accepts connections
1160				       from listed z/VM user IDs only.
1161	
1162		hwthread_map=	[METAG] Comma-separated list of Linux cpu id to
1163				        hardware thread id mappings.
1164					Format: <cpu>:<hwthread>
1165	
1166		keep_bootcon	[KNL]
1167				Do not unregister boot console at start. This is only
1168				useful for debugging when something happens in the window
1169				between unregistering the boot console and initializing
1170				the real console.
1171	
1172		i2c_bus=	[HW] Override the default board specific I2C bus speed
1173				     or register an additional I2C bus that is not
1174				     registered from board initialization code.
1175				     Format:
1176				     <bus_id>,<clkrate>
1177	
1178		i8042.debug	[HW] Toggle i8042 debug mode
1179		i8042.direct	[HW] Put keyboard port into non-translated mode
1180		i8042.dumbkbd	[HW] Pretend that controller can only read data from
1181				     keyboard and cannot control its state
1182				     (Don't attempt to blink the leds)
1183		i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
1184		i8042.nokbd	[HW] Don't check/create keyboard port
1185		i8042.noloop	[HW] Disable the AUX Loopback command while probing
1186				     for the AUX port
1187		i8042.nomux	[HW] Don't check presence of an active multiplexing
1188				     controller
1189		i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1190				     controllers
1191		i8042.notimeout	[HW] Ignore timeout condition signalled by controller
1192		i8042.reset	[HW] Reset the controller during init and cleanup
1193		i8042.unlock	[HW] Unlock (ignore) the keylock
1194	
1195		i810=		[HW,DRM]
1196	
1197		i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
1198				indicates that the driver is running on unsupported
1199				hardware.
1200		i8k.force	[HW] Activate i8k driver even if SMM BIOS signature
1201				does not match list of supported models.
1202		i8k.power_status
1203				[HW] Report power status in /proc/i8k
1204				(disabled by default)
1205		i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN
1206				capability is set.
1207	
1208		i915.invert_brightness=
1209				[DRM] Invert the sense of the variable that is used to
1210				set the brightness of the panel backlight. Normally a
1211				brightness value of 0 indicates backlight switched off,
1212				and the maximum of the brightness value sets the backlight
1213				to maximum brightness. If this parameter is set to 0
1214				(default) and the machine requires it, or this parameter
1215				is set to 1, a brightness value of 0 sets the backlight
1216				to maximum brightness, and the maximum of the brightness
1217				value switches the backlight off.
1218				-1 -- never invert brightness
1219				 0 -- machine default
1220				 1 -- force brightness inversion
1221	
1222		icn=		[HW,ISDN]
1223				Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1224	
1225		ide-core.nodma=	[HW] (E)IDE subsystem
1226				Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1227				.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1228				.cdrom .chs .ignore_cable are additional options
1229				See Documentation/ide/ide.txt.
1230	
1231		ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1232				Claim all unknown PCI IDE storage controllers.
1233	
1234		idle=		[X86]
1235				Format: idle=poll, idle=halt, idle=nomwait
1236				Poll forces a polling idle loop that can slightly
1237				improve the performance of waking up a idle CPU, but
1238				will use a lot of power and make the system run hot.
1239				Not recommended.
1240				idle=halt: Halt is forced to be used for CPU idle.
1241				In such case C2/C3 won't be used again.
1242				idle=nomwait: Disable mwait for CPU C-states
1243	
1244		ignore_loglevel	[KNL]
1245				Ignore loglevel setting - this will print /all/
1246				kernel messages to the console. Useful for debugging.
1247				We also add it as printk module parameter, so users
1248				could change it dynamically, usually by
1249				/sys/module/printk/parameters/ignore_loglevel.
1250	
1251		ihash_entries=	[KNL]
1252				Set number of hash buckets for inode cache.
1253	
1254		ima_appraise=	[IMA] appraise integrity measurements
1255				Format: { "off" | "enforce" | "fix" }
1256				default: "enforce"
1257	
1258		ima_appraise_tcb [IMA]
1259				The builtin appraise policy appraises all files
1260				owned by uid=0.
1261	
1262		ima_hash=	[IMA]
1263				Format: { md5 | sha1 | rmd160 | sha256 | sha384
1264					   | sha512 | ... }
1265				default: "sha1"
1266	
1267				The list of supported hash algorithms is defined
1268				in crypto/hash_info.h.
1269	
1270		ima_tcb		[IMA]
1271				Load a policy which meets the needs of the Trusted
1272				Computing Base.  This means IMA will measure all
1273				programs exec'd, files mmap'd for exec, and all files
1274				opened for read by uid=0.
1275	
1276		ima_template=   [IMA]
1277				Select one of defined IMA measurements template formats.
1278				Formats: { "ima" | "ima-ng" }
1279				Default: "ima-ng"
1280	
1281		init=		[KNL]
1282				Format: <full_path>
1283				Run specified binary instead of /sbin/init as init
1284				process.
1285	
1286		initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
1287				for working out where the kernel is dying during
1288				startup.
1289	
1290		initrd=		[BOOT] Specify the location of the initial ramdisk
1291	
1292		inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
1293				Format: <irq>
1294	
1295		int_pln_enable  [x86] Enable power limit notification interrupt
1296	
1297		integrity_audit=[IMA]
1298				Format: { "0" | "1" }
1299				0 -- basic integrity auditing messages. (Default)
1300				1 -- additional integrity auditing messages.
1301	
1302		intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
1303			on
1304				Enable intel iommu driver.
1305			off
1306				Disable intel iommu driver.
1307			igfx_off [Default Off]
1308				By default, gfx is mapped as normal device. If a gfx
1309				device has a dedicated DMAR unit, the DMAR unit is
1310				bypassed by not enabling DMAR with this option. In
1311				this case, gfx device will use physical address for
1312				DMA.
1313			forcedac [x86_64]
1314				With this option iommu will not optimize to look
1315				for io virtual address below 32-bit forcing dual
1316				address cycle on pci bus for cards supporting greater
1317				than 32-bit addressing. The default is to look
1318				for translation below 32-bit and if not available
1319				then look in the higher range.
1320			strict [Default Off]
1321				With this option on every unmap_single operation will
1322				result in a hardware IOTLB flush operation as opposed
1323				to batching them for performance.
1324			sp_off [Default Off]
1325				By default, super page will be supported if Intel IOMMU
1326				has the capability. With this option, super page will
1327				not be supported.
1328	
1329		intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
1330				0	disables intel_idle and fall back on acpi_idle.
1331				1 to 6	specify maximum depth of C-state.
1332	
1333		intel_pstate=  [X86]
1334			       disable
1335			         Do not enable intel_pstate as the default
1336			         scaling driver for the supported processors
1337	
1338		intremap=	[X86-64, Intel-IOMMU]
1339				on	enable Interrupt Remapping (default)
1340				off	disable Interrupt Remapping
1341				nosid	disable Source ID checking
1342				no_x2apic_optout
1343					BIOS x2APIC opt-out request will be ignored
1344	
1345		iomem=		Disable strict checking of access to MMIO memory
1346			strict	regions from userspace.
1347			relaxed
1348	
1349		iommu=		[x86]
1350			off
1351			force
1352			noforce
1353			biomerge
1354			panic
1355			nopanic
1356			merge
1357			nomerge
1358			forcesac
1359			soft
1360			pt		[x86, IA-64]
1361	
1362	
1363		io7=		[HW] IO7 for Marvel based alpha systems
1364				See comment before marvel_specify_io7 in
1365				arch/alpha/kernel/core_marvel.c.
1366	
1367		io_delay=	[X86] I/O delay method
1368			0x80
1369				Standard port 0x80 based delay
1370			0xed
1371				Alternate port 0xed based delay (needed on some systems)
1372			udelay
1373				Simple two microseconds delay
1374			none
1375				No delay
1376	
1377		ip=		[IP_PNP]
1378				See Documentation/filesystems/nfs/nfsroot.txt.
1379	
1380		ip2=		[HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1381				See comment before ip2_setup() in
1382				drivers/char/ip2/ip2base.c.
1383	
1384		irqfixup	[HW]
1385				When an interrupt is not handled search all handlers
1386				for it. Intended to get systems with badly broken
1387				firmware running.
1388	
1389		irqpoll		[HW]
1390				When an interrupt is not handled search all handlers
1391				for it. Also check all handlers each timer
1392				interrupt. Intended to get systems with badly broken
1393				firmware running.
1394	
1395		isapnp=		[ISAPNP]
1396				Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1397	
1398		isolcpus=	[KNL,SMP] Isolate CPUs from the general scheduler.
1399				Format:
1400				<cpu number>,...,<cpu number>
1401				or
1402				<cpu number>-<cpu number>
1403				(must be a positive range in ascending order)
1404				or a mixture
1405				<cpu number>,...,<cpu number>-<cpu number>
1406	
1407				This option can be used to specify one or more CPUs
1408				to isolate from the general SMP balancing and scheduling
1409				algorithms. You can move a process onto or off an
1410				"isolated" CPU via the CPU affinity syscalls or cpuset.
1411				<cpu number> begins at 0 and the maximum value is
1412				"number of CPUs in system - 1".
1413	
1414				This option is the preferred way to isolate CPUs. The
1415				alternative -- manually setting the CPU mask of all
1416				tasks in the system -- can cause problems and
1417				suboptimal load balancer performance.
1418	
1419		iucv=		[HW,NET]
1420	
1421		ivrs_ioapic	[HW,X86_64]
1422				Provide an override to the IOAPIC-ID<->DEVICE-ID
1423				mapping provided in the IVRS ACPI table. For
1424				example, to map IOAPIC-ID decimal 10 to
1425				PCI device 00:14.0 write the parameter as:
1426					ivrs_ioapic[10]=00:14.0
1427	
1428		ivrs_hpet	[HW,X86_64]
1429				Provide an override to the HPET-ID<->DEVICE-ID
1430				mapping provided in the IVRS ACPI table. For
1431				example, to map HPET-ID decimal 0 to
1432				PCI device 00:14.0 write the parameter as:
1433					ivrs_hpet[0]=00:14.0
1434	
1435		js=		[HW,JOY] Analog joystick
1436				See Documentation/input/joystick.txt.
1437	
1438		keepinitrd	[HW,ARM]
1439	
1440		kernelcore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
1441				specifies the amount of memory usable by the kernel
1442				for non-movable allocations.  The requested amount is
1443				spread evenly throughout all nodes in the system. The
1444				remaining memory in each node is used for Movable
1445				pages. In the event, a node is too small to have both
1446				kernelcore and Movable pages, kernelcore pages will
1447				take priority and other nodes will have a larger number
1448				of Movable pages.  The Movable zone is used for the
1449				allocation of pages that may be reclaimed or moved
1450				by the page migration subsystem.  This means that
1451				HugeTLB pages may not be allocated from this zone.
1452				Note that allocations like PTEs-from-HighMem still
1453				use the HighMem zone if it exists, and the Normal
1454				zone if it does not.
1455	
1456		kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
1457				Format: <Controller#>[,poll interval]
1458				The controller # is the number of the ehci usb debug
1459				port as it is probed via PCI.  The poll interval is
1460				optional and is the number seconds in between
1461				each poll cycle to the debug port in case you need
1462				the functionality for interrupting the kernel with
1463				gdb or control-c on the dbgp connection.  When
1464				not using this parameter you use sysrq-g to break into
1465				the kernel debugger.
1466	
1467		kgdboc=		[KGDB,HW] kgdb over consoles.
1468				Requires a tty driver that supports console polling,
1469				or a supported polling keyboard driver (non-usb).
1470				 Serial only format: <serial_device>[,baud]
1471				 keyboard only format: kbd
1472				 keyboard and serial format: kbd,<serial_device>[,baud]
1473				Optional Kernel mode setting:
1474				 kms, kbd format: kms,kbd
1475				 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1476	
1477		kgdbwait	[KGDB] Stop kernel execution and enter the
1478				kernel debugger at the earliest opportunity.
1479	
1480		kmac=		[MIPS] korina ethernet MAC address.
1481				Configure the RouterBoard 532 series on-chip
1482				Ethernet adapter MAC address.
1483	
1484		kmemleak=	[KNL] Boot-time kmemleak enable/disable
1485				Valid arguments: on, off
1486				Default: on
1487	
1488		kmemcheck=	[X86] Boot-time kmemcheck enable/disable/one-shot mode
1489				Valid arguments: 0, 1, 2
1490				kmemcheck=0 (disabled)
1491				kmemcheck=1 (enabled)
1492				kmemcheck=2 (one-shot mode)
1493				Default: 2 (one-shot mode)
1494	
1495		kstack=N	[X86] Print N words from the kernel stack
1496				in oops dumps.
1497	
1498		kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1499				Default is 0 (don't ignore, but inject #GP)
1500	
1501		kvm.mmu_audit=	[KVM] This is a R/W parameter which allows audit
1502				KVM MMU at runtime.
1503				Default is 0 (off)
1504	
1505		kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.
1506				Default is 1 (enabled)
1507	
1508		kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)
1509				for all guests.
1510				Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1511	
1512		kvm-intel.ept=	[KVM,Intel] Disable extended page tables
1513				(virtualized MMU) support on capable Intel chips.
1514				Default is 1 (enabled)
1515	
1516		kvm-intel.emulate_invalid_guest_state=
1517				[KVM,Intel] Enable emulation of invalid guest states
1518				Default is 0 (disabled)
1519	
1520		kvm-intel.flexpriority=
1521				[KVM,Intel] Disable FlexPriority feature (TPR shadow).
1522				Default is 1 (enabled)
1523	
1524		kvm-intel.nested=
1525				[KVM,Intel] Enable VMX nesting (nVMX).
1526				Default is 0 (disabled)
1527	
1528		kvm-intel.unrestricted_guest=
1529				[KVM,Intel] Disable unrestricted guest feature
1530				(virtualized real and unpaged mode) on capable
1531				Intel chips. Default is 1 (enabled)
1532	
1533		kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification
1534				feature (tagged TLBs) on capable Intel chips.
1535				Default is 1 (enabled)
1536	
1537		l2cr=		[PPC]
1538	
1539		l3cr=		[PPC]
1540	
1541		lapic		[X86-32,APIC] Enable the local APIC even if BIOS
1542				disabled it.
1543	
1544		lapic=		[x86,APIC] "notscdeadline" Do not use TSC deadline
1545				value for LAPIC timer one-shot implementation. Default
1546				back to the programmable timer unit in the LAPIC.
1547	
1548		lapic_timer_c2_ok	[X86,APIC] trust the local apic timer
1549				in C2 power state.
1550	
1551		libata.dma=	[LIBATA] DMA control
1552				libata.dma=0	  Disable all PATA and SATA DMA
1553				libata.dma=1	  PATA and SATA Disk DMA only
1554				libata.dma=2	  ATAPI (CDROM) DMA only
1555				libata.dma=4	  Compact Flash DMA only
1556				Combinations also work, so libata.dma=3 enables DMA
1557				for disks and CDROMs, but not CFs.
1558	
1559		libata.ignore_hpa=	[LIBATA] Ignore HPA limit
1560				libata.ignore_hpa=0	  keep BIOS limits (default)
1561				libata.ignore_hpa=1	  ignore limits, using full disk
1562	
1563		libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
1564				when set.
1565				Format: <int>
1566	
1567		libata.force=	[LIBATA] Force configurations.  The format is comma
1568				separated list of "[ID:]VAL" where ID is
1569				PORT[.DEVICE].  PORT and DEVICE are decimal numbers
1570				matching port, link or device.  Basically, it matches
1571				the ATA ID string printed on console by libata.  If
1572				the whole ID part is omitted, the last PORT and DEVICE
1573				values are used.  If ID hasn't been specified yet, the
1574				configuration applies to all ports, links and devices.
1575	
1576				If only DEVICE is omitted, the parameter applies to
1577				the port and all links and devices behind it.  DEVICE
1578				number of 0 either selects the first device or the
1579				first fan-out link behind PMP device.  It does not
1580				select the host link.  DEVICE number of 15 selects the
1581				host link and device attached to it.
1582	
1583				The VAL specifies the configuration to force.  As long
1584				as there's no ambiguity shortcut notation is allowed.
1585				For example, both 1.5 and 1.5G would work for 1.5Gbps.
1586				The following configurations can be forced.
1587	
1588				* Cable type: 40c, 80c, short40c, unk, ign or sata.
1589				  Any ID with matching PORT is used.
1590	
1591				* SATA link speed limit: 1.5Gbps or 3.0Gbps.
1592	
1593				* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1594				  udma[/][16,25,33,44,66,100,133] notation is also
1595				  allowed.
1596	
1597				* [no]ncq: Turn on or off NCQ.
1598	
1599				* nohrst, nosrst, norst: suppress hard, soft
1600	                          and both resets.
1601	
1602				* rstonce: only attempt one reset during
1603				  hot-unplug link recovery
1604	
1605				* dump_id: dump IDENTIFY data.
1606	
1607				* atapi_dmadir: Enable ATAPI DMADIR bridge support
1608	
1609				* disable: Disable this device.
1610	
1611				If there are multiple matching configurations changing
1612				the same attribute, the last one is used.
1613	
1614		memblock=debug	[KNL] Enable memblock debug messages.
1615	
1616		load_ramdisk=	[RAM] List of ramdisks to load from floppy
1617				See Documentation/blockdev/ramdisk.txt.
1618	
1619		lockd.nlm_grace_period=P  [NFS] Assign grace period.
1620				Format: <integer>
1621	
1622		lockd.nlm_tcpport=N	[NFS] Assign TCP port.
1623				Format: <integer>
1624	
1625		lockd.nlm_timeout=T	[NFS] Assign timeout value.
1626				Format: <integer>
1627	
1628		lockd.nlm_udpport=M	[NFS] Assign UDP port.
1629				Format: <integer>
1630	
1631		logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
1632				Format: <irq>
1633	
1634		loglevel=	All Kernel Messages with a loglevel smaller than the
1635				console loglevel will be printed to the console. It can
1636				also be changed with klogd or other programs. The
1637				loglevels are defined as follows:
1638	
1639				0 (KERN_EMERG)		system is unusable
1640				1 (KERN_ALERT)		action must be taken immediately
1641				2 (KERN_CRIT)		critical conditions
1642				3 (KERN_ERR)		error conditions
1643				4 (KERN_WARNING)	warning conditions
1644				5 (KERN_NOTICE)		normal but significant condition
1645				6 (KERN_INFO)		informational
1646				7 (KERN_DEBUG)		debug-level messages
1647	
1648		log_buf_len=n[KMG]	Sets the size of the printk ring buffer,
1649				in bytes.  n must be a power of two.  The default
1650				size is set in the kernel config file.
1651	
1652		logo.nologo	[FB] Disables display of the built-in Linux logo.
1653				This may be used to provide more screen space for
1654				kernel log messages and is useful when debugging
1655				kernel boot problems.
1656	
1657		lp=0		[LP]	Specify parallel ports to use, e.g,
1658		lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
1659		lp=reset		first parallel port). 'lp=0' disables the
1660		lp=auto			printer driver. 'lp=reset' (which can be
1661					specified in addition to the ports) causes
1662					attached printers to be reset. Using
1663					lp=port1,port2,... specifies the parallel ports
1664					to associate lp devices with, starting with
1665					lp0. A port specification may be 'none' to skip
1666					that lp device, or a parport name such as
1667					'parport0'. Specifying 'lp=auto' instead of a
1668					port specification list means that device IDs
1669					from each port should be examined, to see if
1670					an IEEE 1284-compliant printer is attached; if
1671					so, the driver will manage that printer.
1672					See also header of drivers/char/lp.c.
1673	
1674		lpj=n		[KNL]
1675				Sets loops_per_jiffy to given constant, thus avoiding
1676				time-consuming boot-time autodetection (up to 250 ms per
1677				CPU). 0 enables autodetection (default). To determine
1678				the correct value for your kernel, boot with normal
1679				autodetection and see what value is printed. Note that
1680				on SMP systems the preset will be applied to all CPUs,
1681				which is likely to cause problems if your CPUs need
1682				significantly divergent settings. An incorrect value
1683				will cause delays in the kernel to be wrong, leading to
1684				unpredictable I/O errors and other breakage. Although
1685				unlikely, in the extreme case this might damage your
1686				hardware.
1687	
1688		ltpc=		[NET]
1689				Format: <io>,<irq>,<dma>
1690	
1691		machvec=	[IA-64] Force the use of a particular machine-vector
1692				(machvec) in a generic kernel.
1693				Example: machvec=hpzx1_swiotlb
1694	
1695		machtype=	[Loongson] Share the same kernel image file between different
1696				 yeeloong laptop.
1697				Example: machtype=lemote-yeeloong-2f-7inch
1698	
1699		max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater
1700				than or equal to this physical address is ignored.
1701	
1702		maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
1703				should make use of.  maxcpus=n : n >= 0 limits the
1704				kernel to using 'n' processors.  n=0 is a special case,
1705				it is equivalent to "nosmp", which also disables
1706				the IO APIC.
1707	
1708		max_loop=	[LOOP] The number of loop block devices that get
1709		(loop.max_loop)	unconditionally pre-created at init time. The default
1710				number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1711				of statically allocating a predefined number, loop
1712				devices can be requested on-demand with the
1713				/dev/loop-control interface.
1714	
1715		mce		[X86-32] Machine Check Exception
1716	
1717		mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.txt
1718	
1719		md=		[HW] RAID subsystems devices and level
1720				See Documentation/md.txt.
1721	
1722		mdacon=		[MDA]
1723				Format: <first>,<last>
1724				Specifies range of consoles to be captured by the MDA.
1725	
1726		mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
1727				Amount of memory to be used when the kernel is not able
1728				to see the whole system memory or for test.
1729				[X86] Work as limiting max address. Use together
1730				with memmap= to avoid physical address space collisions.
1731				Without memmap= PCI devices could be placed at addresses
1732				belonging to unused RAM.
1733	
1734		mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
1735				memory.
1736	
1737		memchunk=nn[KMG]
1738				[KNL,SH] Allow user to override the default size for
1739				per-device physically contiguous DMA buffers.
1740	
1741		memmap=exactmap	[KNL,X86] Enable setting of an exact
1742				E820 memory map, as specified by the user.
1743				Such memmap=exactmap lines can be constructed based on
1744				BIOS output or other requirements. See the memmap=nn@ss
1745				option description.
1746	
1747		memmap=nn[KMG]@ss[KMG]
1748				[KNL] Force usage of a specific region of memory.
1749				Region of memory to be used is from ss to ss+nn.
1750	
1751		memmap=nn[KMG]#ss[KMG]
1752				[KNL,ACPI] Mark specific memory as ACPI data.
1753				Region of memory to be marked is from ss to ss+nn.
1754	
1755		memmap=nn[KMG]$ss[KMG]
1756				[KNL,ACPI] Mark specific memory as reserved.
1757				Region of memory to be reserved is from ss to ss+nn.
1758				Example: Exclude memory from 0x18690000-0x1869ffff
1759				         memmap=64K$0x18690000
1760				         or
1761				         memmap=0x10000$0x18690000
1762	
1763		memory_corruption_check=0/1 [X86]
1764				Some BIOSes seem to corrupt the first 64k of
1765				memory when doing things like suspend/resume.
1766				Setting this option will scan the memory
1767				looking for corruption.  Enabling this will
1768				both detect corruption and prevent the kernel
1769				from using the memory being corrupted.
1770				However, its intended as a diagnostic tool; if
1771				repeatable BIOS-originated corruption always
1772				affects the same memory, you can use memmap=
1773				to prevent the kernel from using that memory.
1774	
1775		memory_corruption_check_size=size [X86]
1776				By default it checks for corruption in the low
1777				64k, making this memory unavailable for normal
1778				use.  Use this parameter to scan for
1779				corruption in more or less memory.
1780	
1781		memory_corruption_check_period=seconds [X86]
1782				By default it checks for corruption every 60
1783				seconds.  Use this parameter to check at some
1784				other rate.  0 disables periodic checking.
1785	
1786		memtest=	[KNL,X86] Enable memtest
1787				Format: <integer>
1788				default : 0 <disable>
1789				Specifies the number of memtest passes to be
1790				performed. Each pass selects another test
1791				pattern from a given set of patterns. Memtest
1792				fills the memory with this pattern, validates
1793				memory contents and reserves bad memory
1794				regions that are detected.
1795	
1796		meye.*=		[HW] Set MotionEye Camera parameters
1797				See Documentation/video4linux/meye.txt.
1798	
1799		mfgpt_irq=	[IA-32] Specify the IRQ to use for the
1800				Multi-Function General Purpose Timers on AMD Geode
1801				platforms.
1802	
1803		mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
1804				the BIOS has incorrectly applied a workaround. TinyBIOS
1805				version 0.98 is known to be affected, 0.99 fixes the
1806				problem by letting the user disable the workaround.
1807	
1808		mga=		[HW,DRM]
1809	
1810		min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this
1811				physical address is ignored.
1812	
1813		mini2440=	[ARM,HW,KNL]
1814				Format:[0..2][b][c][t]
1815				Default: "0tb"
1816				MINI2440 configuration specification:
1817				0 - The attached screen is the 3.5" TFT
1818				1 - The attached screen is the 7" TFT
1819				2 - The VGA Shield is attached (1024x768)
1820				Leaving out the screen size parameter will not load
1821				the TFT driver, and the framebuffer will be left
1822				unconfigured.
1823				b - Enable backlight. The TFT backlight pin will be
1824				linked to the kernel VESA blanking code and a GPIO
1825				LED. This parameter is not necessary when using the
1826				VGA shield.
1827				c - Enable the s3c camera interface.
1828				t - Reserved for enabling touchscreen support. The
1829				touchscreen support is not enabled in the mainstream
1830				kernel as of 2.6.30, a preliminary port can be found
1831				in the "bleeding edge" mini2440 support kernel at
1832				http://repo.or.cz/w/linux-2.6/mini2440.git
1833	
1834		mminit_loglevel=
1835				[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1836				parameter allows control of the logging verbosity for
1837				the additional memory initialisation checks. A value
1838				of 0 disables mminit logging and a level of 4 will
1839				log everything. Information is printed at KERN_DEBUG
1840				so loglevel=8 may also need to be specified.
1841	
1842		module.sig_enforce
1843				[KNL] When CONFIG_MODULE_SIG is set, this means that
1844				modules without (valid) signatures will fail to load.
1845				Note that if CONFIG_MODULE_SIG_FORCE is set, that
1846				is always true, so this option does nothing.
1847	
1848		mousedev.tap_time=
1849				[MOUSE] Maximum time between finger touching and
1850				leaving touchpad surface for touch to be considered
1851				a tap and be reported as a left button click (for
1852				touchpads working in absolute mode only).
1853				Format: <msecs>
1854		mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
1855				reporting absolute coordinates, such as tablets
1856		mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
1857				reporting absolute coordinates, such as tablets
1858	
1859		movablecore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
1860				is similar to kernelcore except it specifies the
1861				amount of memory used for migratable allocations.
1862				If both kernelcore and movablecore is specified,
1863				then kernelcore will be at *least* the specified
1864				value but may be more. If movablecore on its own
1865				is specified, the administrator must be careful
1866				that the amount of memory usable for all allocations
1867				is not too small.
1868	
1869		movable_node	[KNL,X86] Boot-time switch to enable the effects
1870				of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
1871	
1872		MTD_Partition=	[MTD]
1873				Format: <name>,<region-number>,<size>,<offset>
1874	
1875		MTD_Region=	[MTD] Format:
1876				<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1877	
1878		mtdparts=	[MTD]
1879				See drivers/mtd/cmdlinepart.c.
1880	
1881		multitce=off	[PPC]  This parameter disables the use of the pSeries
1882				firmware feature for updating multiple TCE entries
1883				at a time.
1884	
1885		onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
1886	
1887				Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1888	
1889				boundary - index of last SLC block on Flex-OneNAND.
1890					   The remaining blocks are configured as MLC blocks.
1891				lock	 - Configure if Flex-OneNAND boundary should be locked.
1892					   Once locked, the boundary cannot be changed.
1893					   1 indicates lock status, 0 indicates unlock status.
1894	
1895		mtdset=		[ARM]
1896				ARM/S3C2412 JIVE boot control
1897	
1898				See arch/arm/mach-s3c2412/mach-jive.c
1899	
1900		mtouchusb.raw_coordinates=
1901				[HW] Make the MicroTouch USB driver use raw coordinates
1902				('y', default) or cooked coordinates ('n')
1903	
1904		mtrr_chunk_size=nn[KMG] [X86]
1905				used for mtrr cleanup. It is largest continuous chunk
1906				that could hold holes aka. UC entries.
1907	
1908		mtrr_gran_size=nn[KMG] [X86]
1909				Used for mtrr cleanup. It is granularity of mtrr block.
1910				Default is 1.
1911				Large value could prevent small alignment from
1912				using up MTRRs.
1913	
1914		mtrr_spare_reg_nr=n [X86]
1915				Format: <integer>
1916				Range: 0,7 : spare reg number
1917				Default : 1
1918				Used for mtrr cleanup. It is spare mtrr entries number.
1919				Set to 2 or more if your graphical card needs more.
1920	
1921		n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card
1922	
1923		netdev=		[NET] Network devices parameters
1924				Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1925				Note that mem_start is often overloaded to mean
1926				something different and driver-specific.
1927				This usage is only documented in each driver source
1928				file if at all.
1929	
1930		nf_conntrack.acct=
1931				[NETFILTER] Enable connection tracking flow accounting
1932				0 to disable accounting
1933				1 to enable accounting
1934				Default value is 0.
1935	
1936		nfsaddrs=	[NFS] Deprecated.  Use ip= instead.
1937				See Documentation/filesystems/nfs/nfsroot.txt.
1938	
1939		nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
1940				See Documentation/filesystems/nfs/nfsroot.txt.
1941	
1942		nfsrootdebug	[NFS] enable nfsroot debugging messages.
1943				See Documentation/filesystems/nfs/nfsroot.txt.
1944	
1945		nfs.callback_tcpport=
1946				[NFS] set the TCP port on which the NFSv4 callback
1947				channel should listen.
1948	
1949		nfs.cache_getent=
1950				[NFS] sets the pathname to the program which is used
1951				to update the NFS client cache entries.
1952	
1953		nfs.cache_getent_timeout=
1954				[NFS] sets the timeout after which an attempt to
1955				update a cache entry is deemed to have failed.
1956	
1957		nfs.idmap_cache_timeout=
1958				[NFS] set the maximum lifetime for idmapper cache
1959				entries.
1960	
1961		nfs.enable_ino64=
1962				[NFS] enable 64-bit inode numbers.
1963				If zero, the NFS client will fake up a 32-bit inode
1964				number for the readdir() and stat() syscalls instead
1965				of returning the full 64-bit number.
1966				The default is to return 64-bit inode numbers.
1967	
1968		nfs.max_session_slots=
1969				[NFSv4.1] Sets the maximum number of session slots
1970				the client will attempt to negotiate with the server.
1971				This limits the number of simultaneous RPC requests
1972				that the client can send to the NFSv4.1 server.
1973				Note that there is little point in setting this
1974				value higher than the max_tcp_slot_table_limit.
1975	
1976		nfs.nfs4_disable_idmapping=
1977				[NFSv4] When set to the default of '1', this option
1978				ensures that both the RPC level authentication
1979				scheme and the NFS level operations agree to use
1980				numeric uids/gids if the mount is using the
1981				'sec=sys' security flavour. In effect it is
1982				disabling idmapping, which can make migration from
1983				legacy NFSv2/v3 systems to NFSv4 easier.
1984				Servers that do not support this mode of operation
1985				will be autodetected by the client, and it will fall
1986				back to using the idmapper.
1987				To turn off this behaviour, set the value to '0'.
1988		nfs.nfs4_unique_id=
1989				[NFS4] Specify an additional fixed unique ident-
1990				ification string that NFSv4 clients can insert into
1991				their nfs_client_id4 string.  This is typically a
1992				UUID that is generated at system install time.
1993	
1994		nfs.send_implementation_id =
1995				[NFSv4.1] Send client implementation identification
1996				information in exchange_id requests.
1997				If zero, no implementation identification information
1998				will be sent.
1999				The default is to send the implementation identification
2000				information.
2001		
2002		nfs.recover_lost_locks =
2003				[NFSv4] Attempt to recover locks that were lost due
2004				to a lease timeout on the server. Please note that
2005				doing this risks data corruption, since there are
2006				no guarantees that the file will remain unchanged
2007				after the locks are lost.
2008				If you want to enable the kernel legacy behaviour of
2009				attempting to recover these locks, then set this
2010				parameter to '1'.
2011				The default parameter value of '0' causes the kernel
2012				not to attempt recovery of lost locks.
2013	
2014		nfsd.nfs4_disable_idmapping=
2015				[NFSv4] When set to the default of '1', the NFSv4
2016				server will return only numeric uids and gids to
2017				clients using auth_sys, and will accept numeric uids
2018				and gids from such clients.  This is intended to ease
2019				migration from NFSv2/v3.
2020	
2021		objlayoutdriver.osd_login_prog=
2022				[NFS] [OBJLAYOUT] sets the pathname to the program which
2023				is used to automatically discover and login into new
2024				osd-targets. Please see:
2025				Documentation/filesystems/pnfs.txt for more explanations
2026	
2027		nmi_debug=	[KNL,AVR32,SH] Specify one or more actions to take
2028				when a NMI is triggered.
2029				Format: [state][,regs][,debounce][,die]
2030	
2031		nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels
2032				Format: [panic,][nopanic,][num]
2033				Valid num: 0
2034				0 - turn nmi_watchdog off
2035				When panic is specified, panic when an NMI watchdog
2036				timeout occurs (or 'nopanic' to override the opposite
2037				default).
2038				This is useful when you use a panic=... timeout and
2039				need the box quickly up again.
2040	
2041		netpoll.carrier_timeout=
2042				[NET] Specifies amount of time (in seconds) that
2043				netpoll should wait for a carrier. By default netpoll
2044				waits 4 seconds.
2045	
2046		no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
2047				emulation library even if a 387 maths coprocessor
2048				is present.
2049	
2050		no_console_suspend
2051				[HW] Never suspend the console
2052				Disable suspending of consoles during suspend and
2053				hibernate operations.  Once disabled, debugging
2054				messages can reach various consoles while the rest
2055				of the system is being put to sleep (ie, while
2056				debugging driver suspend/resume hooks).  This may
2057				not work reliably with all consoles, but is known
2058				to work with serial and VGA consoles.
2059				To facilitate more flexible debugging, we also add
2060				console_suspend, a printk module parameter to control
2061				it. Users could use console_suspend (usually
2062				/sys/module/printk/parameters/console_suspend) to
2063				turn on/off it dynamically.
2064	
2065		noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
2066				caches in the slab allocator.  Saves per-node memory,
2067				but will impact performance.
2068	
2069		noalign		[KNL,ARM]
2070	
2071		noapic		[SMP,APIC] Tells the kernel to not make use of any
2072				IOAPICs that may be present in the system.
2073	
2074		nokaslr		[X86]
2075				Disable kernel and module base offset ASLR (Address
2076				Space Layout Randomization) if built into the kernel.
2077	
2078		noautogroup	Disable scheduler automatic task group creation.
2079	
2080		nobats		[PPC] Do not use BATs for mapping kernel lowmem
2081				on "Classic" PPC cores.
2082	
2083		nocache		[ARM]
2084	
2085		noclflush	[BUGS=X86] Don't use the CLFLUSH instruction
2086	
2087		nodelayacct	[KNL] Disable per-task delay accounting
2088	
2089		nodisconnect	[HW,SCSI,M68K] Disables SCSI disconnects.
2090	
2091		nodsp		[SH] Disable hardware DSP at boot time.
2092	
2093		noefi		[X86] Disable EFI runtime services support.
2094	
2095		noexec		[IA-64]
2096	
2097		noexec		[X86]
2098				On X86-32 available only on PAE configured kernels.
2099				noexec=on: enable non-executable mappings (default)
2100				noexec=off: disable non-executable mappings
2101	
2102		nosmap		[X86]
2103				Disable SMAP (Supervisor Mode Access Prevention)
2104				even if it is supported by processor.
2105	
2106		nosmep		[X86]
2107				Disable SMEP (Supervisor Mode Execution Prevention)
2108				even if it is supported by processor.
2109	
2110		noexec32	[X86-64]
2111				This affects only 32-bit executables.
2112				noexec32=on: enable non-executable mappings (default)
2113					read doesn't imply executable mappings
2114				noexec32=off: disable non-executable mappings
2115					read implies executable mappings
2116	
2117		nofpu		[SH] Disable hardware FPU at boot time.
2118	
2119		nofxsr		[BUGS=X86-32] Disables x86 floating point extended
2120				register save and restore. The kernel will only save
2121				legacy floating-point registers on task switch.
2122	
2123		noxsave		[BUGS=X86] Disables x86 extended register state save
2124				and restore using xsave. The kernel will fallback to
2125				enabling legacy floating-point and sse state.
2126	
2127		eagerfpu=	[X86]
2128				on	enable eager fpu restore
2129				off	disable eager fpu restore
2130				auto	selects the default scheme, which automatically
2131					enables eagerfpu restore for xsaveopt.
2132	
2133		nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
2134				wfi(ARM) instruction doesn't work correctly and not to
2135				use it. This is also useful when using JTAG debugger.
2136	
2137		no_file_caps	Tells the kernel not to honor file capabilities.  The
2138				only way then for a file to be executed with privilege
2139				is to be setuid root or executed by root.
2140	
2141		nohalt		[IA-64] Tells the kernel not to use the power saving
2142				function PAL_HALT_LIGHT when idle. This increases
2143				power-consumption. On the positive side, it reduces
2144				interrupt wake-up latency, which may improve performance
2145				in certain environments such as networked servers or
2146				real-time systems.
2147	
2148		nohz=		[KNL] Boottime enable/disable dynamic ticks
2149				Valid arguments: on, off
2150				Default: on
2151	
2152		nohz_full=	[KNL,BOOT]
2153				In kernels built with CONFIG_NO_HZ_FULL=y, set
2154				the specified list of CPUs whose tick will be stopped
2155				whenever possible. The boot CPU will be forced outside
2156				the range to maintain the timekeeping.
2157				The CPUs in this range must also be included in the
2158				rcu_nocbs= set.
2159	
2160		noiotrap	[SH] Disables trapped I/O port accesses.
2161	
2162		noirqdebug	[X86-32] Disables the code which attempts to detect and
2163				disable unhandled interrupt sources.
2164	
2165		no_timer_check	[X86,APIC] Disables the code which tests for
2166				broken timer IRQ sources.
2167	
2168		noisapnp	[ISAPNP] Disables ISA PnP code.
2169	
2170		noinitrd	[RAM] Tells the kernel not to load any configured
2171				initial RAM disk.
2172	
2173		nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt
2174				remapping.
2175				[Deprecated - use intremap=off]
2176	
2177		nointroute	[IA-64]
2178	
2179		nojitter	[IA-64] Disables jitter checking for ITC timers.
2180	
2181		no-kvmclock	[X86,KVM] Disable paravirtualized KVM clock driver
2182	
2183		no-kvmapf	[X86,KVM] Disable paravirtualized asynchronous page
2184				fault handling.
2185	
2186		no-steal-acc    [X86,KVM] Disable paravirtualized steal time accounting.
2187				steal time is computed, but won't influence scheduler
2188				behaviour
2189	
2190		nolapic		[X86-32,APIC] Do not enable or use the local APIC.
2191	
2192		nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
2193	
2194		noltlbs		[PPC] Do not use large page/tlb entries for kernel
2195				lowmem mapping on PPC40x.
2196	
2197		nomca		[IA-64] Disable machine check abort handling
2198	
2199		nomce		[X86-32] Machine Check Exception
2200	
2201		nomfgpt		[X86-32] Disable Multi-Function General Purpose
2202				Timer usage (for AMD Geode machines).
2203	
2204		nonmi_ipi	[X86] Disable using NMI IPIs during panic/reboot to
2205				shutdown the other cpus.  Instead use the REBOOT_VECTOR
2206				irq.
2207	
2208		nomodule	Disable module load
2209	
2210		nopat		[X86] Disable PAT (page attribute table extension of
2211				pagetables) support.
2212	
2213		norandmaps	Don't use address space randomization.  Equivalent to
2214				echo 0 > /proc/sys/kernel/randomize_va_space
2215	
2216		noreplace-paravirt	[X86,IA-64,PV_OPS] Don't patch paravirt_ops
2217	
2218		noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
2219				with UP alternatives
2220	
2221		nordrand	[X86] Disable kernel use of the RDRAND and
2222				RDSEED instructions even if they are supported
2223				by the processor.  RDRAND and RDSEED are still
2224				available to user space applications.
2225	
2226		noresume	[SWSUSP] Disables resume and restores original swap
2227				space.
2228	
2229		no-scroll	[VGA] Disables scrollback.
2230				This is required for the Braillex ib80-piezo Braille
2231				reader made by F.H. Papenmeier (Germany).
2232	
2233		nosbagart	[IA-64]
2234	
2235		nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
2236	
2237		nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
2238				and disable the IO APIC.  legacy for "maxcpus=0".
2239	
2240		nosoftlockup	[KNL] Disable the soft-lockup detector.
2241	
2242		nosync		[HW,M68K] Disables sync negotiation for all devices.
2243	
2244		notsc		[BUGS=X86-32] Disable Time Stamp Counter
2245	
2246		nousb		[USB] Disable the USB subsystem
2247	
2248		nowatchdog	[KNL] Disable the lockup detector (NMI watchdog).
2249	
2250		nowb		[ARM]
2251	
2252		nox2apic	[X86-64,APIC] Do not enable x2APIC mode.
2253	
2254		cpu0_hotplug	[X86] Turn on CPU0 hotplug feature when
2255				CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
2256				Some features depend on CPU0. Known dependencies are:
2257				1. Resume from suspend/hibernate depends on CPU0.
2258				Suspend/hibernate will fail if CPU0 is offline and you
2259				need to online CPU0 before suspend/hibernate.
2260				2. PIC interrupts also depend on CPU0. CPU0 can't be
2261				removed if a PIC interrupt is detected.
2262				It's said poweroff/reboot may depend on CPU0 on some
2263				machines although I haven't seen such issues so far
2264				after CPU0 is offline on a few tested machines.
2265				If the dependencies are under your control, you can
2266				turn on cpu0_hotplug.
2267	
2268		nptcg=		[IA-64] Override max number of concurrent global TLB
2269				purges which is reported from either PAL_VM_SUMMARY or
2270				SAL PALO.
2271	
2272		nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
2273				could support.  nr_cpus=n : n >= 1 limits the kernel to
2274				supporting 'n' processors. Later in runtime you can not
2275				use hotplug cpu feature to put more cpu back to online.
2276				just like you compile the kernel NR_CPUS=n
2277	
2278		nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
2279	
2280		numa_balancing=	[KNL,X86] Enable or disable automatic NUMA balancing.
2281				Allowed values are enable and disable
2282	
2283		numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2284				one of ['zone', 'node', 'default'] can be specified
2285				This can be set from sysctl after boot.
2286				See Documentation/sysctl/vm.txt for details.
2287	
2288		ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
2289				See Documentation/debugging-via-ohci1394.txt for more
2290				info.
2291	
2292		olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2293				Rather than timing out after 20 ms if an EC
2294				command is not properly ACKed, override the length
2295				of the timeout.  We have interrupts disabled while
2296				waiting for the ACK, so if this is set too high
2297				interrupts *may* be lost!
2298	
2299		omap_mux=	[OMAP] Override bootloader pin multiplexing.
2300				Format: <mux_mode0.mode_name=value>...
2301				For example, to override I2C bus2:
2302				omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2303	
2304		oprofile.timer=	[HW]
2305				Use timer interrupt instead of performance counters
2306	
2307		oprofile.cpu_type=	Force an oprofile cpu type
2308				This might be useful if you have an older oprofile
2309				userland or if you want common events.
2310				Format: { arch_perfmon }
2311				arch_perfmon: [X86] Force use of architectural
2312					perfmon on Intel CPUs instead of the
2313					CPU specific event set.
2314				timer: [X86] Force use of architectural NMI
2315					timer mode (see also oprofile.timer
2316					for generic hr timer mode)
2317					[s390] Force legacy basic mode sampling
2318	                                (report cpu_type "timer")
2319	
2320		oops=panic	Always panic on oopses. Default is to just kill the
2321				process, but there is a small probability of
2322				deadlocking the machine.
2323				This will also cause panics on machine check exceptions.
2324				Useful together with panic=30 to trigger a reboot.
2325	
2326		OSS		[HW,OSS]
2327				See Documentation/sound/oss/oss-parameters.txt
2328	
2329		panic=		[KNL] Kernel behaviour on panic: delay <timeout>
2330				timeout > 0: seconds before rebooting
2331				timeout = 0: wait forever
2332				timeout < 0: reboot immediately
2333				Format: <timeout>
2334	
2335		parkbd.port=	[HW] Parallel port number the keyboard adapter is
2336				connected to, default is 0.
2337				Format: <parport#>
2338		parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
2339				0 for XT, 1 for AT (default is AT).
2340				Format: <mode>
2341	
2342		parport=	[HW,PPT] Specify parallel ports. 0 disables.
2343				Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2344				Use 'auto' to force the driver to use any
2345				IRQ/DMA settings detected (the default is to
2346				ignore detected IRQ/DMA settings because of
2347				possible conflicts). You can specify the base
2348				address, IRQ, and DMA settings; IRQ and DMA
2349				should be numbers, or 'auto' (for using detected
2350				settings on that particular port), or 'nofifo'
2351				(to avoid using a FIFO even if it is detected).
2352				Parallel ports are assigned in the order they
2353				are specified on the command line, starting
2354				with parport0.
2355	
2356		parport_init_mode=	[HW,PPT]
2357				Configure VIA parallel port to operate in
2358				a specific mode. This is necessary on Pegasos
2359				computer where firmware has no options for setting
2360				up parallel port mode and sets it to spp.
2361				Currently this function knows 686a and 8231 chips.
2362				Format: [spp|ps2|epp|ecp|ecpepp]
2363	
2364		pause_on_oops=
2365				Halt all CPUs after the first oops has been printed for
2366				the specified number of seconds.  This is to be used if
2367				your oopses keep scrolling off the screen.
2368	
2369		pcbit=		[HW,ISDN]
2370	
2371		pcd.		[PARIDE]
2372				See header of drivers/block/paride/pcd.c.
2373				See also Documentation/blockdev/paride.txt.
2374	
2375		pci=option[,option...]	[PCI] various PCI subsystem options:
2376			earlydump	[X86] dump PCI config space before the kernel
2377				        changes anything
2378			off		[X86] don't probe for the PCI bus
2379			bios		[X86-32] force use of PCI BIOS, don't access
2380					the hardware directly. Use this if your machine
2381					has a non-standard PCI host bridge.
2382			nobios		[X86-32] disallow use of PCI BIOS, only direct
2383					hardware access methods are allowed. Use this
2384					if you experience crashes upon bootup and you
2385					suspect they are caused by the BIOS.
2386			conf1		[X86] Force use of PCI Configuration
2387					Mechanism 1.
2388			conf2		[X86] Force use of PCI Configuration
2389					Mechanism 2.
2390			noaer		[PCIE] If the PCIEAER kernel config parameter is
2391					enabled, this kernel boot option can be used to
2392					disable the use of PCIE advanced error reporting.
2393			nodomains	[PCI] Disable support for multiple PCI
2394					root domains (aka PCI segments, in ACPI-speak).
2395			nommconf	[X86] Disable use of MMCONFIG for PCI
2396					Configuration
2397			check_enable_amd_mmconf [X86] check for and enable
2398					properly configured MMIO access to PCI
2399					config space on AMD family 10h CPU
2400			nomsi		[MSI] If the PCI_MSI kernel config parameter is
2401					enabled, this kernel boot option can be used to
2402					disable the use of MSI interrupts system-wide.
2403			noioapicquirk	[APIC] Disable all boot interrupt quirks.
2404					Safety option to keep boot IRQs enabled. This
2405					should never be necessary.
2406			ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
2407					primary IO-APIC for bridges that cannot disable
2408					boot IRQs. This fixes a source of spurious IRQs
2409					when the system masks IRQs.
2410			noioapicreroute	[APIC] Disable workaround that uses the
2411					boot IRQ equivalent of an IRQ that connects to
2412					a chipset where boot IRQs cannot be disabled.
2413					The opposite of ioapicreroute.
2414			biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
2415					routing table. These calls are known to be buggy
2416					on several machines and they hang the machine
2417					when used, but on other computers it's the only
2418					way to get the interrupt routing table. Try
2419					this option if the kernel is unable to allocate
2420					IRQs or discover secondary PCI buses on your
2421					motherboard.
2422			rom		[X86] Assign address space to expansion ROMs.
2423					Use with caution as certain devices share
2424					address decoders between ROMs and other
2425					resources.
2426			norom		[X86] Do not assign address space to
2427					expansion ROMs that do not already have
2428					BIOS assigned address ranges.
2429			nobar		[X86] Do not assign address space to the
2430					BARs that weren't assigned by the BIOS.
2431			irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
2432					assigned automatically to PCI devices. You can
2433					make the kernel exclude IRQs of your ISA cards
2434					this way.
2435			pirqaddr=0xAAAAA	[X86] Specify the physical address
2436					of the PIRQ table (normally generated
2437					by the BIOS) if it is outside the
2438					F0000h-100000h range.
2439			lastbus=N	[X86] Scan all buses thru bus #N. Can be
2440					useful if the kernel is unable to find your
2441					secondary buses and you want to tell it
2442					explicitly which ones they are.
2443			assign-busses	[X86] Always assign all PCI bus
2444					numbers ourselves, overriding
2445					whatever the firmware may have done.
2446			usepirqmask	[X86] Honor the possible IRQ mask stored
2447					in the BIOS $PIR table. This is needed on
2448					some systems with broken BIOSes, notably
2449					some HP Pavilion N5400 and Omnibook XE3
2450					notebooks. This will have no effect if ACPI
2451					IRQ routing is enabled.
2452			noacpi		[X86] Do not use ACPI for IRQ routing
2453					or for PCI scanning.
2454			use_crs		[X86] Use PCI host bridge window information
2455					from ACPI.  On BIOSes from 2008 or later, this
2456					is enabled by default.  If you need to use this,
2457					please report a bug.
2458			nocrs		[X86] Ignore PCI host bridge windows from ACPI.
2459				        If you need to use this, please report a bug.
2460			routeirq	Do IRQ routing for all PCI devices.
2461					This is normally done in pci_enable_device(),
2462					so this option is a temporary workaround
2463					for broken drivers that don't call it.
2464			skip_isa_align	[X86] do not align io start addr, so can
2465					handle more pci cards
2466			firmware	[ARM] Do not re-enumerate the bus but instead
2467					just use the configuration from the
2468					bootloader. This is currently used on
2469					IXP2000 systems where the bus has to be
2470					configured a certain way for adjunct CPUs.
2471			noearly		[X86] Don't do any early type 1 scanning.
2472					This might help on some broken boards which
2473					machine check when some devices' config space
2474					is read. But various workarounds are disabled
2475					and some IOMMU drivers will not work.
2476			bfsort		Sort PCI devices into breadth-first order.
2477					This sorting is done to get a device
2478					order compatible with older (<= 2.4) kernels.
2479			nobfsort	Don't sort PCI devices into breadth-first order.
2480			pcie_bus_tune_off	Disable PCIe MPS (Max Payload Size)
2481					tuning and use the BIOS-configured MPS defaults.
2482			pcie_bus_safe	Set every device's MPS to the largest value
2483					supported by all devices below the root complex.
2484			pcie_bus_perf	Set device MPS to the largest allowable MPS
2485					based on its parent bus. Also set MRRS (Max
2486					Read Request Size) to the largest supported
2487					value (no larger than the MPS that the device
2488					or bus can support) for best performance.
2489			pcie_bus_peer2peer	Set every device's MPS to 128B, which
2490					every device is guaranteed to support. This
2491					configuration allows peer-to-peer DMA between
2492					any pair of devices, possibly at the cost of
2493					reduced performance.  This also guarantees
2494					that hot-added devices will work.
2495			cbiosize=nn[KMG]	The fixed amount of bus space which is
2496					reserved for the CardBus bridge's IO window.
2497					The default value is 256 bytes.
2498			cbmemsize=nn[KMG]	The fixed amount of bus space which is
2499					reserved for the CardBus bridge's memory
2500					window. The default value is 64 megabytes.
2501			resource_alignment=
2502					Format:
2503					[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2504					Specifies alignment and device to reassign
2505					aligned memory resources.
2506					If <order of align> is not specified,
2507					PAGE_SIZE is used as alignment.
2508					PCI-PCI bridge can be specified, if resource
2509					windows need to be expanded.
2510			ecrc=		Enable/disable PCIe ECRC (transaction layer
2511					end-to-end CRC checking).
2512					bios: Use BIOS/firmware settings. This is the
2513					the default.
2514					off: Turn ECRC off
2515					on: Turn ECRC on.
2516			hpiosize=nn[KMG]	The fixed amount of bus space which is
2517					reserved for hotplug bridge's IO window.
2518					Default size is 256 bytes.
2519			hpmemsize=nn[KMG]	The fixed amount of bus space which is
2520					reserved for hotplug bridge's memory window.
2521					Default size is 2 megabytes.
2522			realloc=	Enable/disable reallocating PCI bridge resources
2523					if allocations done by BIOS are too small to
2524					accommodate resources required by all child
2525					devices.
2526					off: Turn realloc off
2527					on: Turn realloc on
2528			realloc		same as realloc=on
2529			noari		do not use PCIe ARI.
2530			pcie_scan_all	Scan all possible PCIe devices.  Otherwise we
2531					only look for one device below a PCIe downstream
2532					port.
2533	
2534		pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
2535				Management.
2536			off	Disable ASPM.
2537			force	Enable ASPM even on devices that claim not to support it.
2538				WARNING: Forcing ASPM on may cause system lockups.
2539	
2540		pcie_hp=	[PCIE] PCI Express Hotplug driver options:
2541			nomsi	Do not use MSI for PCI Express Native Hotplug (this
2542				makes all PCIe ports use INTx for hotplug services).
2543	
2544		pcie_ports=	[PCIE] PCIe ports handling:
2545			auto	Ask the BIOS whether or not to use native PCIe services
2546				associated with PCIe ports (PME, hot-plug, AER).  Use
2547				them only if that is allowed by the BIOS.
2548			native	Use native PCIe services associated with PCIe ports
2549				unconditionally.
2550			compat	Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2551				ports driver.
2552	
2553		pcie_pme=	[PCIE,PM] Native PCIe PME signaling options:
2554			nomsi	Do not use MSI for native PCIe PME signaling (this makes
2555				all PCIe root ports use INTx for all services).
2556	
2557		pcmv=		[HW,PCMCIA] BadgePAD 4
2558	
2559		pd_ignore_unused
2560				[PM]
2561				Keep all power-domains already enabled by bootloader on,
2562				even if no driver has claimed them. This is useful
2563				for debug and development, but should not be
2564				needed on a platform with proper driver support.
2565	
2566		pd.		[PARIDE]
2567				See Documentation/blockdev/paride.txt.
2568	
2569		pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
2570				boot time.
2571				Format: { 0 | 1 }
2572				See arch/parisc/kernel/pdc_chassis.c
2573	
2574		percpu_alloc=	Select which percpu first chunk allocator to use.
2575				Currently supported values are "embed" and "page".
2576				Archs may support subset or none of the	selections.
2577				See comments in mm/percpu.c for details on each
2578				allocator.  This parameter is primarily	for debugging
2579				and performance comparison.
2580	
2581		pf.		[PARIDE]
2582				See Documentation/blockdev/paride.txt.
2583	
2584		pg.		[PARIDE]
2585				See Documentation/blockdev/paride.txt.
2586	
2587		pirq=		[SMP,APIC] Manual mp-table setup
2588				See Documentation/x86/i386/IO-APIC.txt.
2589	
2590		plip=		[PPT,NET] Parallel port network link
2591				Format: { parport<nr> | timid | 0 }
2592				See also Documentation/parport.txt.
2593	
2594		pmtmr=		[X86] Manual setup of pmtmr I/O Port.
2595				Override pmtimer IOPort with a hex value.
2596				e.g. pmtmr=0x508
2597	
2598		pnp.debug=1	[PNP]
2599				Enable PNP debug messages (depends on the
2600				CONFIG_PNP_DEBUG_MESSAGES option).  Change at run-time
2601				via /sys/module/pnp/parameters/debug.  We always show
2602				current resource usage; turning this on also shows
2603				possible settings and some assignment information.
2604	
2605		pnpacpi=	[ACPI]
2606				{ off }
2607	
2608		pnpbios=	[ISAPNP]
2609				{ on | off | curr | res | no-curr | no-res }
2610	
2611		pnp_reserve_irq=
2612				[ISAPNP] Exclude IRQs for the autoconfiguration
2613	
2614		pnp_reserve_dma=
2615				[ISAPNP] Exclude DMAs for the autoconfiguration
2616	
2617		pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
2618				Ranges are in pairs (I/O port base and size).
2619	
2620		pnp_reserve_mem=
2621				[ISAPNP] Exclude memory regions for the
2622				autoconfiguration.
2623				Ranges are in pairs (memory base and size).
2624	
2625		ports=		[IP_VS_FTP] IPVS ftp helper module
2626				Default is 21.
2627				Up to 8 (IP_VS_APP_MAX_PORTS) ports
2628				may be specified.
2629				Format: <port>,<port>....
2630	
2631		print-fatal-signals=
2632				[KNL] debug: print fatal signals
2633	
2634				If enabled, warn about various signal handling
2635				related application anomalies: too many signals,
2636				too many POSIX.1 timers, fatal signals causing a
2637				coredump - etc.
2638	
2639				If you hit the warning due to signal overflow,
2640				you might want to try "ulimit -i unlimited".
2641	
2642				default: off.
2643	
2644		printk.always_kmsg_dump=
2645				Trigger kmsg_dump for cases other than kernel oops or
2646				panics
2647				Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
2648				default: disabled
2649	
2650		printk.time=	Show timing data prefixed to each printk message line
2651				Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
2652	
2653		processor.max_cstate=	[HW,ACPI]
2654				Limit processor to maximum C-state
2655				max_cstate=9 overrides any DMI blacklist limit.
2656	
2657		processor.nocst	[HW,ACPI]
2658				Ignore the _CST method to determine C-states,
2659				instead using the legacy FADT method
2660	
2661		profile=	[KNL] Enable kernel profiling via /proc/profile
2662				Format: [schedule,]<number>
2663				Param: "schedule" - profile schedule points.
2664				Param: <number> - step/bucket size as a power of 2 for
2665					statistical time based profiling.
2666				Param: "sleep" - profile D-state sleeping (millisecs).
2667					Requires CONFIG_SCHEDSTATS
2668				Param: "kvm" - profile VM exits.
2669	
2670		prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk
2671				before loading.
2672				See Documentation/blockdev/ramdisk.txt.
2673	
2674		psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
2675				probe for; one of (bare|imps|exps|lifebook|any).
2676		psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
2677				per second.
2678		psmouse.resetafter=	[HW,MOUSE]
2679				Try to reset the device after so many bad packets
2680				(0 = never).
2681		psmouse.resolution=
2682				[HW,MOUSE] Set desired mouse resolution, in dpi.
2683		psmouse.smartscroll=
2684				[HW,MOUSE] Controls Logitech smartscroll autorepeat.
2685				0 = disabled, 1 = enabled (default).
2686	
2687		pstore.backend=	Specify the name of the pstore backend to use
2688	
2689		pt.		[PARIDE]
2690				See Documentation/blockdev/paride.txt.
2691	
2692		pty.legacy_count=
2693				[KNL] Number of legacy pty's. Overwrites compiled-in
2694				default number.
2695	
2696		quiet		[KNL] Disable most log messages
2697	
2698		r128=		[HW,DRM]
2699	
2700		raid=		[HW,RAID]
2701				See Documentation/md.txt.
2702	
2703		ramdisk_blocksize=	[RAM]
2704				See Documentation/blockdev/ramdisk.txt.
2705	
2706		ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
2707				See Documentation/blockdev/ramdisk.txt.
2708	
2709		rcu_nocbs=	[KNL]
2710				In kernels built with CONFIG_RCU_NOCB_CPU=y, set
2711				the specified list of CPUs to be no-callback CPUs.
2712				Invocation of these CPUs' RCU callbacks will
2713				be offloaded to "rcuox/N" kthreads created for
2714				that purpose, where "x" is "b" for RCU-bh, "p"
2715				for RCU-preempt, and "s" for RCU-sched, and "N"
2716				is the CPU number.  This reduces OS jitter on the
2717				offloaded CPUs, which can be useful for HPC and
2718				real-time workloads.  It can also improve energy
2719				efficiency for asymmetric multiprocessors.
2720	
2721		rcu_nocb_poll	[KNL]
2722				Rather than requiring that offloaded CPUs
2723				(specified by rcu_nocbs= above) explicitly
2724				awaken the corresponding "rcuoN" kthreads,
2725				make these kthreads poll for callbacks.
2726				This improves the real-time response for the
2727				offloaded CPUs by relieving them of the need to
2728				wake up the corresponding kthread, but degrades
2729				energy efficiency by requiring that the kthreads
2730				periodically wake up to do the polling.
2731	
2732		rcutree.blimit=	[KNL]
2733				Set maximum number of finished RCU callbacks to
2734				process in one batch.
2735	
2736		rcutree.rcu_fanout_leaf= [KNL]
2737				Increase the number of CPUs assigned to each
2738				leaf rcu_node structure.  Useful for very large
2739				systems.
2740	
2741		rcutree.jiffies_till_first_fqs= [KNL]
2742				Set delay from grace-period initialization to
2743				first attempt to force quiescent states.
2744				Units are jiffies, minimum value is zero,
2745				and maximum value is HZ.
2746	
2747		rcutree.jiffies_till_next_fqs= [KNL]
2748				Set delay between subsequent attempts to force
2749				quiescent states.  Units are jiffies, minimum
2750				value is one, and maximum value is HZ.
2751	
2752		rcutree.qhimark= [KNL]
2753				Set threshold of queued RCU callbacks beyond which
2754				batch limiting is disabled.
2755	
2756		rcutree.qlowmark= [KNL]
2757				Set threshold of queued RCU callbacks below which
2758				batch limiting is re-enabled.
2759	
2760		rcutree.rcu_idle_gp_delay= [KNL]
2761				Set wakeup interval for idle CPUs that have
2762				RCU callbacks (RCU_FAST_NO_HZ=y).
2763	
2764		rcutree.rcu_idle_lazy_gp_delay= [KNL]
2765				Set wakeup interval for idle CPUs that have
2766				only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
2767				Lazy RCU callbacks are those which RCU can
2768				prove do nothing more than free memory.
2769	
2770		rcutorture.fqs_duration= [KNL]
2771				Set duration of force_quiescent_state bursts.
2772	
2773		rcutorture.fqs_holdoff= [KNL]
2774				Set holdoff time within force_quiescent_state bursts.
2775	
2776		rcutorture.fqs_stutter= [KNL]
2777				Set wait time between force_quiescent_state bursts.
2778	
2779		rcutorture.gp_exp= [KNL]
2780				Use expedited update-side primitives.
2781	
2782		rcutorture.gp_normal= [KNL]
2783				Use normal (non-expedited) update-side primitives.
2784				If both gp_exp and gp_normal are set, do both.
2785				If neither gp_exp nor gp_normal are set, still
2786				do both.
2787	
2788		rcutorture.n_barrier_cbs= [KNL]
2789				Set callbacks/threads for rcu_barrier() testing.
2790	
2791		rcutorture.nfakewriters= [KNL]
2792				Set number of concurrent RCU writers.  These just
2793				stress RCU, they don't participate in the actual
2794				test, hence the "fake".
2795	
2796		rcutorture.nreaders= [KNL]
2797				Set number of RCU readers.
2798	
2799		rcutorture.object_debug= [KNL]
2800				Enable debug-object double-call_rcu() testing.
2801	
2802		rcutorture.onoff_holdoff= [KNL]
2803				Set time (s) after boot for CPU-hotplug testing.
2804	
2805		rcutorture.onoff_interval= [KNL]
2806				Set time (s) between CPU-hotplug operations, or
2807				zero to disable CPU-hotplug testing.
2808	
2809		rcutorture.rcutorture_runnable= [BOOT]
2810				Start rcutorture running at boot time.
2811	
2812		rcutorture.shuffle_interval= [KNL]
2813				Set task-shuffle interval (s).  Shuffling tasks
2814				allows some CPUs to go into dyntick-idle mode
2815				during the rcutorture test.
2816	
2817		rcutorture.shutdown_secs= [KNL]
2818				Set time (s) after boot system shutdown.  This
2819				is useful for hands-off automated testing.
2820	
2821		rcutorture.stall_cpu= [KNL]
2822				Duration of CPU stall (s) to test RCU CPU stall
2823				warnings, zero to disable.
2824	
2825		rcutorture.stall_cpu_holdoff= [KNL]
2826				Time to wait (s) after boot before inducing stall.
2827	
2828		rcutorture.stat_interval= [KNL]
2829				Time (s) between statistics printk()s.
2830	
2831		rcutorture.stutter= [KNL]
2832				Time (s) to stutter testing, for example, specifying
2833				five seconds causes the test to run for five seconds,
2834				wait for five seconds, and so on.  This tests RCU's
2835				ability to transition abruptly to and from idle.
2836	
2837		rcutorture.test_boost= [KNL]
2838				Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
2839				"Maybe" means test if the RCU implementation
2840				under test support RCU priority boosting.
2841	
2842		rcutorture.test_boost_duration= [KNL]
2843				Duration (s) of each individual boost test.
2844	
2845		rcutorture.test_boost_interval= [KNL]
2846				Interval (s) between each boost test.
2847	
2848		rcutorture.test_no_idle_hz= [KNL]
2849				Test RCU's dyntick-idle handling.  See also the
2850				rcutorture.shuffle_interval parameter.
2851	
2852		rcutorture.torture_type= [KNL]
2853				Specify the RCU implementation to test.
2854	
2855		rcutorture.verbose= [KNL]
2856				Enable additional printk() statements.
2857	
2858		rcupdate.rcu_expedited= [KNL]
2859				Use expedited grace-period primitives, for
2860				example, synchronize_rcu_expedited() instead
2861				of synchronize_rcu().  This reduces latency,
2862				but can increase CPU utilization, degrade
2863				real-time latency, and degrade energy efficiency.
2864	
2865		rcupdate.rcu_cpu_stall_suppress= [KNL]
2866				Suppress RCU CPU stall warning messages.
2867	
2868		rcupdate.rcu_cpu_stall_timeout= [KNL]
2869				Set timeout for RCU CPU stall warning messages.
2870	
2871		rdinit=		[KNL]
2872				Format: <full_path>
2873				Run specified binary instead of /init from the ramdisk,
2874				used for early userspace startup. See initrd.
2875	
2876		reboot=		[KNL]
2877				Format (x86 or x86_64):
2878					[w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
2879					[[,]s[mp]#### \
2880					[[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
2881					[[,]f[orce]
2882				Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
2883				      reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
2884				      reboot_force is either force or not specified,
2885				      reboot_cpu is s[mp]#### with #### being the processor
2886						to be used for rebooting.
2887	
2888		relax_domain_level=
2889				[KNL, SMP] Set scheduler's default relax_domain_level.
2890				See Documentation/cgroups/cpusets.txt.
2891	
2892		reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area
2893	
2894		reservetop=	[X86-32]
2895				Format: nn[KMG]
2896				Reserves a hole at the top of the kernel virtual
2897				address space.
2898	
2899		reservelow=	[X86]
2900				Format: nn[K]
2901				Set the amount of memory to reserve for BIOS at
2902				the bottom of the address space.
2903	
2904		reset_devices	[KNL] Force drivers to reset the underlying device
2905				during initialization.
2906	
2907		resume=		[SWSUSP]
2908				Specify the partition device for software suspend
2909				Format:
2910				{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
2911	
2912		resume_offset=	[SWSUSP]
2913				Specify the offset from the beginning of the partition
2914				given by "resume=" at which the swap header is located,
2915				in <PAGE_SIZE> units (needed only for swap files).
2916				See  Documentation/power/swsusp-and-swap-files.txt
2917	
2918		resumedelay=	[HIBERNATION] Delay (in seconds) to pause before attempting to
2919				read the resume files
2920	
2921		resumewait	[HIBERNATION] Wait (indefinitely) for resume device to show up.
2922				Useful for devices that are detected asynchronously
2923				(e.g. USB and MMC devices).
2924	
2925		hibernate=	[HIBERNATION]
2926			noresume	Don't check if there's a hibernation image
2927					present during boot.
2928			nocompress	Don't compress/decompress hibernation images.
2929	
2930		retain_initrd	[RAM] Keep initrd memory after extraction
2931	
2932		rhash_entries=	[KNL,NET]
2933				Set number of hash buckets for route cache
2934	
2935		ro		[KNL] Mount root device read-only on boot
2936	
2937		root=		[KNL] Root filesystem
2938				See name_to_dev_t comment in init/do_mounts.c.
2939	
2940		rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
2941				mount the root filesystem
2942	
2943		rootflags=	[KNL] Set root filesystem mount option string
2944	
2945		rootfstype=	[KNL] Set root filesystem type
2946	
2947		rootwait	[KNL] Wait (indefinitely) for root device to show up.
2948				Useful for devices that are detected asynchronously
2949				(e.g. USB and MMC devices).
2950	
2951		rproc_mem=nn[KMG][@address]
2952				[KNL,ARM,CMA] Remoteproc physical memory block.
2953				Memory area to be used by remote processor image,
2954				managed by CMA.
2955	
2956		rw		[KNL] Mount root device read-write on boot
2957	
2958		S		[KNL] Run init in single mode
2959	
2960		sa1100ir	[NET]
2961				See drivers/net/irda/sa1100_ir.c.
2962	
2963		sbni=		[NET] Granch SBNI12 leased line adapter
2964	
2965		sched_debug	[KNL] Enables verbose scheduler debug messages.
2966	
2967		skew_tick=	[KNL] Offset the periodic timer tick per cpu to mitigate
2968				xtime_lock contention on larger systems, and/or RCU lock
2969				contention on all systems with CONFIG_MAXSMP set.
2970				Format: { "0" | "1" }
2971				0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
2972				1 -- enable.
2973				Note: increases power consumption, thus should only be
2974				enabled if running jitter sensitive (HPC/RT) workloads.
2975	
2976		security=	[SECURITY] Choose a security module to enable at boot.
2977				If this boot parameter is not specified, only the first
2978				security module asking for security registration will be
2979				loaded. An invalid security module name will be treated
2980				as if no module has been chosen.
2981	
2982		selinux=	[SELINUX] Disable or enable SELinux at boot time.
2983				Format: { "0" | "1" }
2984				See security/selinux/Kconfig help text.
2985				0 -- disable.
2986				1 -- enable.
2987				Default value is set via kernel config option.
2988				If enabled at boot time, /selinux/disable can be used
2989				later to disable prior to initial policy load.
2990	
2991		apparmor=	[APPARMOR] Disable or enable AppArmor at boot time
2992				Format: { "0" | "1" }
2993				See security/apparmor/Kconfig help text
2994				0 -- disable.
2995				1 -- enable.
2996				Default value is set via kernel config option.
2997	
2998		serialnumber	[BUGS=X86-32]
2999	
3000		shapers=	[NET]
3001				Maximal number of shapers.
3002	
3003		show_msr=	[x86] show boot-time MSR settings
3004				Format: { <integer> }
3005				Show boot-time (BIOS-initialized) MSR settings.
3006				The parameter means the number of CPUs to show,
3007				for example 1 means boot CPU only.
3008	
3009		simeth=		[IA-64]
3010		simscsi=
3011	
3012		slram=		[HW,MTD]
3013	
3014		slab_max_order=	[MM, SLAB]
3015				Determines the maximum allowed order for slabs.
3016				A high setting may cause OOMs due to memory
3017				fragmentation.  Defaults to 1 for systems with
3018				more than 32MB of RAM, 0 otherwise.
3019	
3020		slub_debug[=options[,slabs]]	[MM, SLUB]
3021				Enabling slub_debug allows one to determine the
3022				culprit if slab objects become corrupted. Enabling
3023				slub_debug can create guard zones around objects and
3024				may poison objects when not in use. Also tracks the
3025				last alloc / free. For more information see
3026				Documentation/vm/slub.txt.
3027	
3028		slub_max_order= [MM, SLUB]
3029				Determines the maximum allowed order for slabs.
3030				A high setting may cause OOMs due to memory
3031				fragmentation. For more information see
3032				Documentation/vm/slub.txt.
3033	
3034		slub_min_objects=	[MM, SLUB]
3035				The minimum number of objects per slab. SLUB will
3036				increase the slab order up to slub_max_order to
3037				generate a sufficiently large slab able to contain
3038				the number of objects indicated. The higher the number
3039				of objects the smaller the overhead of tracking slabs
3040				and the less frequently locks need to be acquired.
3041				For more information see Documentation/vm/slub.txt.
3042	
3043		slub_min_order=	[MM, SLUB]
3044				Determines the minimum page order for slabs. Must be
3045				lower than slub_max_order.
3046				For more information see Documentation/vm/slub.txt.
3047	
3048		slub_nomerge	[MM, SLUB]
3049				Disable merging of slabs with similar size. May be
3050				necessary if there is some reason to distinguish
3051				allocs to different slabs. Debug options disable
3052				merging on their own.
3053				For more information see Documentation/vm/slub.txt.
3054	
3055		smart2=		[HW]
3056				Format: <io1>[,<io2>[,...,<io8>]]
3057	
3058		smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
3059		smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
3060		smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
3061		smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
3062		smsc-ircc2.ircc_irq=	[HW] IRQ line
3063		smsc-ircc2.ircc_dma=	[HW] DMA channel
3064		smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
3065					0: Toshiba Satellite 1800 (GP data pin select)
3066					1: Fast pin select (default)
3067					2: ATC IRMode
3068	
3069		softlockup_panic=
3070				[KNL] Should the soft-lockup detector generate panics.
3071				Format: <integer>
3072	
3073		sonypi.*=	[HW] Sony Programmable I/O Control Device driver
3074				See Documentation/laptops/sonypi.txt
3075	
3076		spia_io_base=	[HW,MTD]
3077		spia_fio_base=
3078		spia_pedr=
3079		spia_peddr=
3080	
3081		stacktrace	[FTRACE]
3082				Enabled the stack tracer on boot up.
3083	
3084		stacktrace_filter=[function-list]
3085				[FTRACE] Limit the functions that the stack tracer
3086				will trace at boot up. function-list is a comma separated
3087				list of functions. This list can be changed at run
3088				time by the stack_trace_filter file in the debugfs
3089				tracing directory. Note, this enables stack tracing
3090				and the stacktrace above is not needed.
3091	
3092		sti=		[PARISC,HW]
3093				Format: <num>
3094				Set the STI (builtin display/keyboard on the HP-PARISC
3095				machines) console (graphic card) which should be used
3096				as the initial boot-console.
3097				See also comment in drivers/video/console/sticore.c.
3098	
3099		sti_font=	[HW]
3100				See comment in drivers/video/console/sticore.c.
3101	
3102		stifb=		[HW]
3103				Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
3104	
3105		sunrpc.min_resvport=
3106		sunrpc.max_resvport=
3107				[NFS,SUNRPC]
3108				SunRPC servers often require that client requests
3109				originate from a privileged port (i.e. a port in the
3110				range 0 < portnr < 1024).
3111				An administrator who wishes to reserve some of these
3112				ports for other uses may adjust the range that the
3113				kernel's sunrpc client considers to be privileged
3114				using these two parameters to set the minimum and
3115				maximum port values.
3116	
3117		sunrpc.pool_mode=
3118				[NFS]
3119				Control how the NFS server code allocates CPUs to
3120				service thread pools.  Depending on how many NICs
3121				you have and where their interrupts are bound, this
3122				option will affect which CPUs will do NFS serving.
3123				Note: this parameter cannot be changed while the
3124				NFS server is running.
3125	
3126				auto	    the server chooses an appropriate mode
3127					    automatically using heuristics
3128				global	    a single global pool contains all CPUs
3129				percpu	    one pool for each CPU
3130				pernode	    one pool for each NUMA node (equivalent
3131					    to global on non-NUMA machines)
3132	
3133		sunrpc.tcp_slot_table_entries=
3134		sunrpc.udp_slot_table_entries=
3135				[NFS,SUNRPC]
3136				Sets the upper limit on the number of simultaneous
3137				RPC calls that can be sent from the client to a
3138				server. Increasing these values may allow you to
3139				improve throughput, but will also increase the
3140				amount of memory reserved for use by the client.
3141	
3142		swapaccount=[0|1]
3143				[KNL] Enable accounting of swap in memory resource
3144				controller if no parameter or 1 is given or disable
3145				it if 0 is given (See Documentation/cgroups/memory.txt)
3146	
3147		swiotlb=	[ARM,IA-64,PPC,MIPS,X86]
3148				Format: { <int> | force }
3149				<int> -- Number of I/O TLB slabs
3150				force -- force using of bounce buffers even if they
3151				         wouldn't be automatically used by the kernel
3152	
3153		switches=	[HW,M68k]
3154	
3155		sysfs.deprecated=0|1 [KNL]
3156				Enable/disable old style sysfs layout for old udev
3157				on older distributions. When this option is enabled
3158				very new udev will not work anymore. When this option
3159				is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
3160				in older udev will not work anymore.
3161				Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
3162				the kernel configuration.
3163	
3164		sysrq_always_enabled
3165				[KNL]
3166				Ignore sysrq setting - this boot parameter will
3167				neutralize any effect of /proc/sys/kernel/sysrq.
3168				Useful for debugging.
3169	
3170		tdfx=		[HW,DRM]
3171	
3172		test_suspend=	[SUSPEND]
3173				Specify "mem" (for Suspend-to-RAM) or "standby" (for
3174				standby suspend) as the system sleep state to briefly
3175				enter during system startup.  The system is woken from
3176				this state using a wakeup-capable RTC alarm.
3177	
3178		thash_entries=	[KNL,NET]
3179				Set number of hash buckets for TCP connection
3180	
3181		thermal.act=	[HW,ACPI]
3182				-1: disable all active trip points in all thermal zones
3183				<degrees C>: override all lowest active trip points
3184	
3185		thermal.crt=	[HW,ACPI]
3186				-1: disable all critical trip points in all thermal zones
3187				<degrees C>: override all critical trip points
3188	
3189		thermal.nocrt=	[HW,ACPI]
3190				Set to disable actions on ACPI thermal zone
3191				critical and hot trip points.
3192	
3193		thermal.off=	[HW,ACPI]
3194				1: disable ACPI thermal control
3195	
3196		thermal.psv=	[HW,ACPI]
3197				-1: disable all passive trip points
3198				<degrees C>: override all passive trip points to this
3199				value
3200	
3201		thermal.tzp=	[HW,ACPI]
3202				Specify global default ACPI thermal zone polling rate
3203				<deci-seconds>: poll all this frequency
3204				0: no polling (default)
3205	
3206		threadirqs	[KNL]
3207				Force threading of all interrupt handlers except those
3208				marked explicitly IRQF_NO_THREAD.
3209	
3210		tmem		[KNL,XEN]
3211				Enable the Transcendent memory driver if built-in.
3212	
3213		tmem.cleancache=0|1 [KNL, XEN]
3214				Default is on (1). Disable the usage of the cleancache
3215				API to send anonymous pages to the hypervisor.
3216	
3217		tmem.frontswap=0|1 [KNL, XEN]
3218				Default is on (1). Disable the usage of the frontswap
3219				API to send swap pages to the hypervisor. If disabled
3220				the selfballooning and selfshrinking are force disabled.
3221	
3222		tmem.selfballooning=0|1 [KNL, XEN]
3223				Default is on (1). Disable the driving of swap pages
3224				to the hypervisor.
3225	
3226		tmem.selfshrinking=0|1 [KNL, XEN]
3227				Default is on (1). Partial swapoff that immediately
3228				transfers pages from Xen hypervisor back to the
3229				kernel based on different criteria.
3230	
3231		topology=	[S390]
3232				Format: {off | on}
3233				Specify if the kernel should make use of the cpu
3234				topology information if the hardware supports this.
3235				The scheduler will make use of this information and
3236				e.g. base its process migration decisions on it.
3237				Default is on.
3238	
3239		tp720=		[HW,PS2]
3240	
3241		tpm_suspend_pcr=[HW,TPM]
3242				Format: integer pcr id
3243				Specify that at suspend time, the tpm driver
3244				should extend the specified pcr with zeros,
3245				as a workaround for some chips which fail to
3246				flush the last written pcr on TPM_SaveState.
3247				This will guarantee that all the other pcrs
3248				are saved.
3249	
3250		trace_buf_size=nn[KMG]
3251				[FTRACE] will set tracing buffer size.
3252	
3253		trace_event=[event-list]
3254				[FTRACE] Set and start specified trace events in order
3255				to facilitate early boot debugging.
3256				See also Documentation/trace/events.txt
3257	
3258		trace_options=[option-list]
3259				[FTRACE] Enable or disable tracer options at boot.
3260				The option-list is a comma delimited list of options
3261				that can be enabled or disabled just as if you were
3262				to echo the option name into
3263	
3264				    /sys/kernel/debug/tracing/trace_options
3265	
3266				For example, to enable stacktrace option (to dump the
3267				stack trace of each event), add to the command line:
3268	
3269				      trace_options=stacktrace
3270	
3271				See also Documentation/trace/ftrace.txt "trace options"
3272				section.
3273	
3274		traceoff_on_warning
3275				[FTRACE] enable this option to disable tracing when a
3276				warning is hit. This turns off "tracing_on". Tracing can
3277				be enabled again by echoing '1' into the "tracing_on"
3278				file located in /sys/kernel/debug/tracing/
3279	
3280				This option is useful, as it disables the trace before
3281				the WARNING dump is called, which prevents the trace to
3282				be filled with content caused by the warning output.
3283	
3284				This option can also be set at run time via the sysctl
3285				option:  kernel/traceoff_on_warning
3286	
3287		transparent_hugepage=
3288				[KNL]
3289				Format: [always|madvise|never]
3290				Can be used to control the default behavior of the system
3291				with respect to transparent hugepages.
3292				See Documentation/vm/transhuge.txt for more details.
3293	
3294		tsc=		Disable clocksource stability checks for TSC.
3295				Format: <string>
3296				[x86] reliable: mark tsc clocksource as reliable, this
3297				disables clocksource verification at runtime, as well
3298				as the stability checks done at bootup.	Used to enable
3299				high-resolution timer mode on older hardware, and in
3300				virtualized environment.
3301				[x86] noirqtime: Do not use TSC to do irq accounting.
3302				Used to run time disable IRQ_TIME_ACCOUNTING on any
3303				platforms where RDTSC is slow and this accounting
3304				can add overhead.
3305	
3306		turbografx.map[2|3]=	[HW,JOY]
3307				TurboGraFX parallel port interface
3308				Format:
3309				<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
3310				See also Documentation/input/joystick-parport.txt
3311	
3312		udbg-immortal	[PPC] When debugging early kernel crashes that
3313				happen after console_init() and before a proper 
3314				console driver takes over, this boot options might
3315				help "seeing" what's going on.
3316	
3317		uhash_entries=	[KNL,NET]
3318				Set number of hash buckets for UDP/UDP-Lite connections
3319	
3320		uhci-hcd.ignore_oc=
3321				[USB] Ignore overcurrent events (default N).
3322				Some badly-designed motherboards generate lots of
3323				bogus events, for ports that aren't wired to
3324				anything.  Set this parameter to avoid log spamming.
3325				Note that genuine overcurrent events won't be
3326				reported either.
3327	
3328		unknown_nmi_panic
3329				[X86] Cause panic on unknown NMI.
3330	
3331		usbcore.authorized_default=
3332				[USB] Default USB device authorization:
3333				(default -1 = authorized except for wireless USB,
3334				0 = not authorized, 1 = authorized)
3335	
3336		usbcore.autosuspend=
3337				[USB] The autosuspend time delay (in seconds) used
3338				for newly-detected USB devices (default 2).  This
3339				is the time required before an idle device will be
3340				autosuspended.  Devices for which the delay is set
3341				to a negative value won't be autosuspended at all.
3342	
3343		usbcore.usbfs_snoop=
3344				[USB] Set to log all usbfs traffic (default 0 = off).
3345	
3346		usbcore.blinkenlights=
3347				[USB] Set to cycle leds on hubs (default 0 = off).
3348	
3349		usbcore.old_scheme_first=
3350				[USB] Start with the old device initialization
3351				scheme (default 0 = off).
3352	
3353		usbcore.usbfs_memory_mb=
3354				[USB] Memory limit (in MB) for buffers allocated by
3355				usbfs (default = 16, 0 = max = 2047).
3356	
3357		usbcore.use_both_schemes=
3358				[USB] Try the other device initialization scheme
3359				if the first one fails (default 1 = enabled).
3360	
3361		usbcore.initial_descriptor_timeout=
3362				[USB] Specifies timeout for the initial 64-byte
3363	                        USB_REQ_GET_DESCRIPTOR request in milliseconds
3364				(default 5000 = 5.0 seconds).
3365	
3366		usbhid.mousepoll=
3367				[USBHID] The interval which mice are to be polled at.
3368	
3369		usb-storage.delay_use=
3370				[UMS] The delay in seconds before a new device is
3371				scanned for Logical Units (default 5).
3372	
3373		usb-storage.quirks=
3374				[UMS] A list of quirks entries to supplement or
3375				override the built-in unusual_devs list.  List
3376				entries are separated by commas.  Each entry has
3377				the form VID:PID:Flags where VID and PID are Vendor
3378				and Product ID values (4-digit hex numbers) and
3379				Flags is a set of characters, each corresponding
3380				to a common usb-storage quirk flag as follows:
3381					a = SANE_SENSE (collect more than 18 bytes
3382						of sense data);
3383					b = BAD_SENSE (don't collect more than 18
3384						bytes of sense data);
3385					c = FIX_CAPACITY (decrease the reported
3386						device capacity by one sector);
3387					d = NO_READ_DISC_INFO (don't use
3388						READ_DISC_INFO command);
3389					e = NO_READ_CAPACITY_16 (don't use
3390						READ_CAPACITY_16 command);
3391					h = CAPACITY_HEURISTICS (decrease the
3392						reported device capacity by one
3393						sector if the number is odd);
3394					i = IGNORE_DEVICE (don't bind to this
3395						device);
3396					l = NOT_LOCKABLE (don't try to lock and
3397						unlock ejectable media);
3398					m = MAX_SECTORS_64 (don't transfer more
3399						than 64 sectors = 32 KB at a time);
3400					n = INITIAL_READ10 (force a retry of the
3401						initial READ(10) command);
3402					o = CAPACITY_OK (accept the capacity
3403						reported by the device);
3404					p = WRITE_CACHE (the device cache is ON
3405						by default);
3406					r = IGNORE_RESIDUE (the device reports
3407						bogus residue values);
3408					s = SINGLE_LUN (the device has only one
3409						Logical Unit);
3410					w = NO_WP_DETECT (don't test whether the
3411						medium is write-protected).
3412				Example: quirks=0419:aaf5:rl,0421:0433:rc
3413	
3414		user_debug=	[KNL,ARM]
3415				Format: <int>
3416				See arch/arm/Kconfig.debug help text.
3417					 1 - undefined instruction events
3418					 2 - system calls
3419					 4 - invalid data aborts
3420					 8 - SIGSEGV faults
3421					16 - SIGBUS faults
3422				Example: user_debug=31
3423	
3424		userpte=
3425				[X86] Flags controlling user PTE allocations.
3426	
3427					nohigh = do not allocate PTE pages in
3428						HIGHMEM regardless of setting
3429						of CONFIG_HIGHPTE.
3430	
3431		vdso=		[X86,SH]
3432				On X86_32, this is an alias for vdso32=.  Otherwise:
3433	
3434				vdso=1: enable VDSO (the default)
3435				vdso=0: disable VDSO mapping
3436	
3437		vdso32=		[X86] Control the 32-bit vDSO
3438				vdso32=1: enable 32-bit VDSO
3439				vdso32=0 or vdso32=2: disable 32-bit VDSO
3440	
3441				See the help text for CONFIG_COMPAT_VDSO for more
3442				details.  If CONFIG_COMPAT_VDSO is set, the default is
3443				vdso32=0; otherwise, the default is vdso32=1.
3444	
3445				For compatibility with older kernels, vdso32=2 is an
3446				alias for vdso32=0.
3447	
3448				Try vdso32=0 if you encounter an error that says:
3449				dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
3450	
3451		vector=		[IA-64,SMP]
3452				vector=percpu: enable percpu vector domain
3453	
3454		video=		[FB] Frame buffer configuration
3455				See Documentation/fb/modedb.txt.
3456	
3457		video.brightness_switch_enabled= [0,1]
3458				If set to 1, on receiving an ACPI notify event
3459				generated by hotkey, video driver will adjust brightness
3460				level and then send out the event to user space through
3461				the allocated input device; If set to 0, video driver
3462				will only send out the event without touching backlight
3463				brightness level.
3464				default: 1
3465	
3466		virtio_mmio.device=
3467				[VMMIO] Memory mapped virtio (platform) device.
3468	
3469					<size>@<baseaddr>:<irq>[:<id>]
3470				where:
3471					<size>     := size (can use standard suffixes
3472							like K, M and G)
3473					<baseaddr> := physical base address
3474					<irq>      := interrupt number (as passed to
3475							request_irq())
3476					<id>       := (optional) platform device id
3477				example:
3478					virtio_mmio.device=1K@0x100b0000:48:7
3479	
3480				Can be used multiple times for multiple devices.
3481	
3482		vga=		[BOOT,X86-32] Select a particular video mode
3483				See Documentation/x86/boot.txt and
3484				Documentation/svga.txt.
3485				Use vga=ask for menu.
3486				This is actually a boot loader parameter; the value is
3487				passed to the kernel using a special protocol.
3488	
3489		vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
3490				size of <nn>. This can be used to increase the
3491				minimum size (128MB on x86). It can also be used to
3492				decrease the size and leave more room for directly
3493				mapped kernel RAM.
3494	
3495		vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
3496				Format: <command>
3497	
3498		vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
3499				Format: <command>
3500	
3501		vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
3502				Format: <command>
3503	
3504		vsyscall=	[X86-64]
3505				Controls the behavior of vsyscalls (i.e. calls to
3506				fixed addresses of 0xffffffffff600x00 from legacy
3507				code).  Most statically-linked binaries and older
3508				versions of glibc use these calls.  Because these
3509				functions are at fixed addresses, they make nice
3510				targets for exploits that can control RIP.
3511	
3512				emulate     [default] Vsyscalls turn into traps and are
3513				            emulated reasonably safely.
3514	
3515				native      Vsyscalls are native syscall instructions.
3516				            This is a little bit faster than trapping
3517				            and makes a few dynamic recompilers work
3518				            better than they would in emulation mode.
3519				            It also makes exploits much easier to write.
3520	
3521				none        Vsyscalls don't work at all.  This makes
3522				            them quite hard to use for exploits but
3523				            might break your system.
3524	
3525		vt.color=	[VT] Default text color.
3526				Format: 0xYX, X = foreground, Y = background.
3527				Default: 0x07 = light gray on black.
3528	
3529		vt.cur_default=	[VT] Default cursor shape.
3530				Format: 0xCCBBAA, where AA, BB, and CC are the same as
3531				the parameters of the <Esc>[?A;B;Cc escape sequence;
3532				see VGA-softcursor.txt. Default: 2 = underline.
3533	
3534		vt.default_blu=	[VT]
3535				Format: <blue0>,<blue1>,<blue2>,...,<blue15>
3536				Change the default blue palette of the console.
3537				This is a 16-member array composed of values
3538				ranging from 0-255.
3539	
3540		vt.default_grn=	[VT]
3541				Format: <green0>,<green1>,<green2>,...,<green15>
3542				Change the default green palette of the console.
3543				This is a 16-member array composed of values
3544				ranging from 0-255.
3545	
3546		vt.default_red=	[VT]
3547				Format: <red0>,<red1>,<red2>,...,<red15>
3548				Change the default red palette of the console.
3549				This is a 16-member array composed of values
3550				ranging from 0-255.
3551	
3552		vt.default_utf8=
3553				[VT]
3554				Format=<0|1>
3555				Set system-wide default UTF-8 mode for all tty's.
3556				Default is 1, i.e. UTF-8 mode is enabled for all
3557				newly opened terminals.
3558	
3559		vt.global_cursor_default=
3560				[VT]
3561				Format=<-1|0|1>
3562				Set system-wide default for whether a cursor
3563				is shown on new VTs. Default is -1,
3564				i.e. cursors will be created by default unless
3565				overridden by individual drivers. 0 will hide
3566				cursors, 1 will display them.
3567	
3568		vt.italic=	[VT] Default color for italic text; 0-15.
3569				Default: 2 = green.
3570	
3571		vt.underline=	[VT] Default color for underlined text; 0-15.
3572				Default: 3 = cyan.
3573	
3574		watchdog timers	[HW,WDT] For information on watchdog timers,
3575				see Documentation/watchdog/watchdog-parameters.txt
3576				or other driver-specific files in the
3577				Documentation/watchdog/ directory.
3578	
3579		workqueue.disable_numa
3580				By default, all work items queued to unbound
3581				workqueues are affine to the NUMA nodes they're
3582				issued on, which results in better behavior in
3583				general.  If NUMA affinity needs to be disabled for
3584				whatever reason, this option can be used.  Note
3585				that this also can be controlled per-workqueue for
3586				workqueues visible under /sys/bus/workqueue/.
3587	
3588		workqueue.power_efficient
3589				Per-cpu workqueues are generally preferred because
3590				they show better performance thanks to cache
3591				locality; unfortunately, per-cpu workqueues tend to
3592				be more power hungry than unbound workqueues.
3593	
3594				Enabling this makes the per-cpu workqueues which
3595				were observed to contribute significantly to power
3596				consumption unbound, leading to measurably lower
3597				power usage at the cost of small performance
3598				overhead.
3599	
3600				The default value of this parameter is determined by
3601				the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
3602	
3603		x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
3604				default x2apic cluster mode on platforms
3605				supporting x2apic.
3606	
3607		x86_intel_mid_timer= [X86-32,APBT]
3608				Choose timer option for x86 Intel MID platform.
3609				Two valid options are apbt timer only and lapic timer
3610				plus one apbt timer for broadcast timer.
3611				x86_intel_mid_timer=apbt_only | lapic_and_apbt
3612	
3613		xen_emul_unplug=		[HW,X86,XEN]
3614				Unplug Xen emulated devices
3615				Format: [unplug0,][unplug1]
3616				ide-disks -- unplug primary master IDE devices
3617				aux-ide-disks -- unplug non-primary-master IDE devices
3618				nics -- unplug network devices
3619				all -- unplug all emulated devices (NICs and IDE disks)
3620				unnecessary -- unplugging emulated devices is
3621					unnecessary even if the host did not respond to
3622					the unplug protocol
3623				never -- do not unplug even if version check succeeds
3624	
3625		xen_nopvspin	[X86,XEN]
3626				Disables the ticketlock slowpath using Xen PV
3627				optimizations.
3628	
3629		xirc2ps_cs=	[NET,PCMCIA]
3630				Format:
3631				<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
3632	
3633	______________________________________________________________________
3634	
3635	TODO:
3636	
3637		Add more DRM drivers.
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