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Based on kernel version 4.7.2. Page generated on 2016-08-22 22:46 EST.

1	                          Kernel Parameters
2	                          ~~~~~~~~~~~~~~~~~
4	The following is a consolidated list of the kernel parameters as
5	implemented by the __setup(), core_param() and module_param() macros
6	and sorted into English Dictionary order (defined as ignoring all
7	punctuation and sorting digits before letters in a case insensitive
8	manner), and with descriptions where known.
10	The kernel parses parameters from the kernel command line up to "--";
11	if it doesn't recognize a parameter and it doesn't contain a '.', the
12	parameter gets passed to init: parameters with '=' go into init's
13	environment, others are passed as command line arguments to init.
14	Everything after "--" is passed as an argument to init.
16	Module parameters can be specified in two ways: via the kernel command
17	line with a module name prefix, or via modprobe, e.g.:
19		(kernel command line) usbcore.blinkenlights=1
20		(modprobe command line) modprobe usbcore blinkenlights=1
22	Parameters for modules which are built into the kernel need to be
23	specified on the kernel command line.  modprobe looks through the
24	kernel command line (/proc/cmdline) and collects module parameters
25	when it loads a module, so the kernel command line can be used for
26	loadable modules too.
28	Hyphens (dashes) and underscores are equivalent in parameter names, so
29		log_buf_len=1M print-fatal-signals=1
30	can also be entered as
31		log-buf-len=1M print_fatal_signals=1
33	Double-quotes can be used to protect spaces in values, e.g.:
34		param="spaces in here"
36	This document may not be entirely up to date and comprehensive. The command
37	"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
38	module. Loadable modules, after being loaded into the running kernel, also
39	reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
40	parameters may be changed at runtime by the command
41	"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
43	The parameters listed below are only valid if certain kernel build options were
44	enabled and if respective hardware is present. The text in square brackets at
45	the beginning of each description states the restrictions within which a
46	parameter is applicable:
48		ACPI	ACPI support is enabled.
49		AGP	AGP (Accelerated Graphics Port) is enabled.
50		ALSA	ALSA sound support is enabled.
51		APIC	APIC support is enabled.
52		APM	Advanced Power Management support is enabled.
53		ARM	ARM architecture is enabled.
54		AVR32	AVR32 architecture is enabled.
55		AX25	Appropriate AX.25 support is enabled.
56		BLACKFIN Blackfin architecture is enabled.
57		CLK	Common clock infrastructure is enabled.
58		CMA	Contiguous Memory Area support is enabled.
59		DRM	Direct Rendering Management support is enabled.
60		DYNAMIC_DEBUG Build in debug messages and enable them at runtime
61		EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled
62		EFI	EFI Partitioning (GPT) is enabled
63		EIDE	EIDE/ATAPI support is enabled.
64		EVM	Extended Verification Module
65		FB	The frame buffer device is enabled.
66		FTRACE	Function tracing enabled.
67		GCOV	GCOV profiling is enabled.
68		HW	Appropriate hardware is enabled.
69		IA-64	IA-64 architecture is enabled.
70		IMA     Integrity measurement architecture is enabled.
71		IOSCHED	More than one I/O scheduler is enabled.
72		IP_PNP	IP DHCP, BOOTP, or RARP is enabled.
73		IPV6	IPv6 support is enabled.
74		ISAPNP	ISA PnP code is enabled.
75		ISDN	Appropriate ISDN support is enabled.
76		JOY	Appropriate joystick support is enabled.
77		KGDB	Kernel debugger support is enabled.
78		KVM	Kernel Virtual Machine support is enabled.
79		LIBATA  Libata driver is enabled
80		LP	Printer support is enabled.
81		LOOP	Loopback device support is enabled.
82		M68k	M68k architecture is enabled.
83				These options have more detailed description inside of
84				Documentation/m68k/kernel-options.txt.
85		MDA	MDA console support is enabled.
86		MIPS	MIPS architecture is enabled.
87		MOUSE	Appropriate mouse support is enabled.
88		MSI	Message Signaled Interrupts (PCI).
89		MTD	MTD (Memory Technology Device) support is enabled.
90		NET	Appropriate network support is enabled.
91		NUMA	NUMA support is enabled.
92		NFS	Appropriate NFS support is enabled.
93		OSS	OSS sound support is enabled.
94		PV_OPS	A paravirtualized kernel is enabled.
95		PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.
96		PARISC	The PA-RISC architecture is enabled.
97		PCI	PCI bus support is enabled.
98		PCIE	PCI Express support is enabled.
99		PCMCIA	The PCMCIA subsystem is enabled.
100		PNP	Plug & Play support is enabled.
101		PPC	PowerPC architecture is enabled.
102		PPT	Parallel port support is enabled.
103		PS2	Appropriate PS/2 support is enabled.
104		RAM	RAM disk support is enabled.
105		S390	S390 architecture is enabled.
106		SCSI	Appropriate SCSI support is enabled.
107				A lot of drivers have their options described inside
108				the Documentation/scsi/ sub-directory.
109		SECURITY Different security models are enabled.
110		SELINUX SELinux support is enabled.
111		APPARMOR AppArmor support is enabled.
112		SERIAL	Serial support is enabled.
113		SH	SuperH architecture is enabled.
114		SMP	The kernel is an SMP kernel.
115		SPARC	Sparc architecture is enabled.
116		SWSUSP	Software suspend (hibernation) is enabled.
117		SUSPEND	System suspend states are enabled.
118		TPM	TPM drivers are enabled.
119		TS	Appropriate touchscreen support is enabled.
120		UMS	USB Mass Storage support is enabled.
121		USB	USB support is enabled.
122		USBHID	USB Human Interface Device support is enabled.
123		V4L	Video For Linux support is enabled.
124		VMMIO   Driver for memory mapped virtio devices is enabled.
125		VGA	The VGA console has been enabled.
126		VT	Virtual terminal support is enabled.
127		WDT	Watchdog support is enabled.
128		XT	IBM PC/XT MFM hard disk support is enabled.
129		X86-32	X86-32, aka i386 architecture is enabled.
130		X86-64	X86-64 architecture is enabled.
131				More X86-64 boot options can be found in
132				Documentation/x86/x86_64/boot-options.txt .
133		X86	Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
134		X86_UV	SGI UV support is enabled.
135		XEN	Xen support is enabled
137	In addition, the following text indicates that the option:
139		BUGS=	Relates to possible processor bugs on the said processor.
140		KNL	Is a kernel start-up parameter.
141		BOOT	Is a boot loader parameter.
143	Parameters denoted with BOOT are actually interpreted by the boot
144	loader, and have no meaning to the kernel directly.
145	Do not modify the syntax of boot loader parameters without extreme
146	need or coordination with <Documentation/x86/boot.txt>.
148	There are also arch-specific kernel-parameters not documented here.
149	See for example <Documentation/x86/x86_64/boot-options.txt>.
151	Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
152	a trailing = on the name of any parameter states that that parameter will
153	be entered as an environment variable, whereas its absence indicates that
154	it will appear as a kernel argument readable via /proc/cmdline by programs
155	running once the system is up.
157	The number of kernel parameters is not limited, but the length of the
158	complete command line (parameters including spaces etc.) is limited to
159	a fixed number of characters. This limit depends on the architecture
160	and is between 256 and 4096 characters. It is defined in the file
161	./include/asm/setup.h as COMMAND_LINE_SIZE.
163	Finally, the [KMG] suffix is commonly described after a number of kernel
164	parameter values. These 'K', 'M', and 'G' letters represent the _binary_
165	multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
166	bytes respectively. Such letter suffixes can also be entirely omitted.
169		acpi=		[HW,ACPI,X86,ARM64]
170				Advanced Configuration and Power Interface
171				Format: { force | on | off | strict | noirq | rsdt |
172					  copy_dsdt }
173				force -- enable ACPI if default was off
174				on -- enable ACPI but allow fallback to DT [arm64]
175				off -- disable ACPI if default was on
176				noirq -- do not use ACPI for IRQ routing
177				strict -- Be less tolerant of platforms that are not
178					strictly ACPI specification compliant.
179				rsdt -- prefer RSDT over (default) XSDT
180				copy_dsdt -- copy DSDT to memory
181				For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force"
182				are available
184				See also Documentation/power/runtime_pm.txt, pci=noacpi
186		acpi_apic_instance=	[ACPI, IOAPIC]
187				Format: <int>
188				2: use 2nd APIC table, if available
189				1,0: use 1st APIC table
190				default: 0
192		acpi_backlight=	[HW,ACPI]
193				acpi_backlight=vendor
194				acpi_backlight=video
195				If set to vendor, prefer vendor specific driver
196				(e.g. thinkpad_acpi, sony_acpi, etc.) instead
197				of the ACPI video.ko driver.
199		acpi_force_32bit_fadt_addr
200				force FADT to use 32 bit addresses rather than the
201				64 bit X_* addresses. Some firmware have broken 64
202				bit addresses for force ACPI ignore these and use
203				the older legacy 32 bit addresses.
205		acpica_no_return_repair [HW, ACPI]
206				Disable AML predefined validation mechanism
207				This mechanism can repair the evaluation result to make
208				the return objects more ACPI specification compliant.
209				This option is useful for developers to identify the
210				root cause of an AML interpreter issue when the issue
211				has something to do with the repair mechanism.
213		acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
214		acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
215				Format: <int>
216				CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
217				debug output.  Bits in debug_layer correspond to a
218				_COMPONENT in an ACPI source file, e.g.,
220				Bits in debug_level correspond to a level in
221				ACPI_DEBUG_PRINT statements, e.g.,
223				The debug_level mask defaults to "info".  See
224				Documentation/acpi/debug.txt for more information about
225				debug layers and levels.
227				Enable processor driver info messages:
228				    acpi.debug_layer=0x20000000
229				Enable PCI/PCI interrupt routing info messages:
230				    acpi.debug_layer=0x400000
231				Enable AML "Debug" output, i.e., stores to the Debug
232				object while interpreting AML:
233				    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
234				Enable all messages related to ACPI hardware:
235				    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
237				Some values produce so much output that the system is
238				unusable.  The "log_buf_len" parameter may be useful
239				if you need to capture more output.
241		acpi_enforce_resources=	[ACPI]
242				{ strict | lax | no }
243				Check for resource conflicts between native drivers
244				and ACPI OperationRegions (SystemIO and SystemMemory
245				only). IO ports and memory declared in ACPI might be
246				used by the ACPI subsystem in arbitrary AML code and
247				can interfere with legacy drivers.
248				strict (default): access to resources claimed by ACPI
249				is denied; legacy drivers trying to access reserved
250				resources will fail to bind to device using them.
251				lax: access to resources claimed by ACPI is allowed;
252				legacy drivers trying to access reserved resources
253				will bind successfully but a warning message is logged.
254				no: ACPI OperationRegions are not marked as reserved,
255				no further checks are performed.
257		acpi_force_table_verification	[HW,ACPI]
258				Enable table checksum verification during early stage.
259				By default, this is disabled due to x86 early mapping
260				size limitation.
262		acpi_irq_balance [HW,ACPI]
263				ACPI will balance active IRQs
264				default in APIC mode
266		acpi_irq_nobalance [HW,ACPI]
267				ACPI will not move active IRQs (default)
268				default in PIC mode
270		acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
271				Format: <irq>,<irq>...
273		acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
274				use by PCI
275				Format: <irq>,<irq>...
277		acpi_no_auto_serialize	[HW,ACPI]
278				Disable auto-serialization of AML methods
279				AML control methods that contain the opcodes to create
280				named objects will be marked as "Serialized" by the
281				auto-serialization feature.
282				This feature is enabled by default.
283				This option allows to turn off the feature.
285		acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kdump
286				   kernels.
288		acpi_no_static_ssdt	[HW,ACPI]
289				Disable installation of static SSDTs at early boot time
290				By default, SSDTs contained in the RSDT/XSDT will be
291				installed automatically and they will appear under
292				/sys/firmware/acpi/tables.
293				This option turns off this feature.
294				Note that specifying this option does not affect
295				dynamic table installation which will install SSDT
296				tables to /sys/firmware/acpi/tables/dynamic.
298		acpi_rsdp=	[ACPI,EFI,KEXEC]
299				Pass the RSDP address to the kernel, mostly used
300				on machines running EFI runtime service to boot the
301				second kernel for kdump.
303		acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
304				Format: To spoof as Windows 98: ="Microsoft Windows"
306		acpi_rev_override [ACPI] Override the _REV object to return 5 (instead
307				of 2 which is mandated by ACPI 6) as the supported ACPI
308				specification revision (when using this switch, it may
309				be necessary to carry out a cold reboot _twice_ in a
310				row to make it take effect on the platform firmware).
312		acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
313				acpi_osi="string1"	# add string1
314				acpi_osi="!string2"	# remove string2
315				acpi_osi=!*		# remove all strings
316				acpi_osi=!		# disable all built-in OS vendor
317							  strings
318				acpi_osi=!!		# enable all built-in OS vendor
319							  strings
320				acpi_osi=		# disable all strings
322				'acpi_osi=!' can be used in combination with single or
323				multiple 'acpi_osi="string1"' to support specific OS
324				vendor string(s).  Note that such command can only
325				affect the default state of the OS vendor strings, thus
326				it cannot affect the default state of the feature group
327				strings and the current state of the OS vendor strings,
328				specifying it multiple times through kernel command line
329				is meaningless.  This command is useful when one do not
330				care about the state of the feature group strings which
331				should be controlled by the OSPM.
332				Examples:
333				  1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
334				     to 'acpi_osi="Windows 2000" acpi_osi=!', they all
335				     can make '_OSI("Windows 2000")' TRUE.
337				'acpi_osi=' cannot be used in combination with other
338				'acpi_osi=' command lines, the _OSI method will not
339				exist in the ACPI namespace.  NOTE that such command can
340				only affect the _OSI support state, thus specifying it
341				multiple times through kernel command line is also
342				meaningless.
343				Examples:
344				  1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
345				     FALSE.
347				'acpi_osi=!*' can be used in combination with single or
348				multiple 'acpi_osi="string1"' to support specific
349				string(s).  Note that such command can affect the
350				current state of both the OS vendor strings and the
351				feature group strings, thus specifying it multiple times
352				through kernel command line is meaningful.  But it may
353				still not able to affect the final state of a string if
354				there are quirks related to this string.  This command
355				is useful when one want to control the state of the
356				feature group strings to debug BIOS issues related to
357				the OSPM features.
358				Examples:
359				  1. 'acpi_osi="Module Device" acpi_osi=!*' can make
360				     '_OSI("Module Device")' FALSE.
361				  2. 'acpi_osi=!* acpi_osi="Module Device"' can make
362				     '_OSI("Module Device")' TRUE.
363				  3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
364				     equivalent to
365				     'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
366				     and
367				     'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
368				     they all will make '_OSI("Windows 2000")' TRUE.
370		acpi_pm_good	[X86]
371				Override the pmtimer bug detection: force the kernel
372				to assume that this machine's pmtimer latches its value
373				and always returns good values.
375		acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
376				Format: { level | edge | high | low }
378		acpi_skip_timer_override [HW,ACPI]
379				Recognize and ignore IRQ0/pin2 Interrupt Override.
380				For broken nForce2 BIOS resulting in XT-PIC timer.
382		acpi_sleep=	[HW,ACPI] Sleep options
383				Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
384					  old_ordering, nonvs, sci_force_enable }
385				See Documentation/power/video.txt for information on
386				s3_bios and s3_mode.
387				s3_beep is for debugging; it makes the PC's speaker beep
388				as soon as the kernel's real-mode entry point is called.
389				s4_nohwsig prevents ACPI hardware signature from being
390				used during resume from hibernation.
391				old_ordering causes the ACPI 1.0 ordering of the _PTS
392				control method, with respect to putting devices into
393				low power states, to be enforced (the ACPI 2.0 ordering
394				of _PTS is used by default).
395				nonvs prevents the kernel from saving/restoring the
396				ACPI NVS memory during suspend/hibernation and resume.
397				sci_force_enable causes the kernel to set SCI_EN directly
398				on resume from S1/S3 (which is against the ACPI spec,
399				but some broken systems don't work without it).
401		acpi_use_timer_override [HW,ACPI]
402				Use timer override. For some broken Nvidia NF5 boards
403				that require a timer override, but don't have HPET
405		add_efi_memmap	[EFI; X86] Include EFI memory map in
406				kernel's map of available physical RAM.
408		agp=		[AGP]
409				{ off | try_unsupported }
410				off: disable AGP support
411				try_unsupported: try to drive unsupported chipsets
412					(may crash computer or cause data corruption)
414		ALSA		[HW,ALSA]
415				See Documentation/sound/alsa/alsa-parameters.txt
417		alignment=	[KNL,ARM]
418				Allow the default userspace alignment fault handler
419				behaviour to be specified.  Bit 0 enables warnings,
420				bit 1 enables fixups, and bit 2 sends a segfault.
422		align_va_addr=	[X86-64]
423				Align virtual addresses by clearing slice [14:12] when
424				allocating a VMA at process creation time. This option
425				gives you up to 3% performance improvement on AMD F15h
426				machines (where it is enabled by default) for a
427				CPU-intensive style benchmark, and it can vary highly in
428				a microbenchmark depending on workload and compiler.
430				32: only for 32-bit processes
431				64: only for 64-bit processes
432				on: enable for both 32- and 64-bit processes
433				off: disable for both 32- and 64-bit processes
435		alloc_snapshot	[FTRACE]
436				Allocate the ftrace snapshot buffer on boot up when the
437				main buffer is allocated. This is handy if debugging
438				and you need to use tracing_snapshot() on boot up, and
439				do not want to use tracing_snapshot_alloc() as it needs
440				to be done where GFP_KERNEL allocations are allowed.
442		amd_iommu=	[HW,X86-64]
443				Pass parameters to the AMD IOMMU driver in the system.
444				Possible values are:
445				fullflush - enable flushing of IO/TLB entries when
446					    they are unmapped. Otherwise they are
447					    flushed before they will be reused, which
448					    is a lot of faster
449				off	  - do not initialize any AMD IOMMU found in
450					    the system
451				force_isolation - Force device isolation for all
452						  devices. The IOMMU driver is not
453						  allowed anymore to lift isolation
454						  requirements as needed. This option
455						  does not override iommu=pt
457		amd_iommu_dump=	[HW,X86-64]
458				Enable AMD IOMMU driver option to dump the ACPI table
459				for AMD IOMMU. With this option enabled, AMD IOMMU
460				driver will print ACPI tables for AMD IOMMU during
461				IOMMU initialization.
463		amijoy.map=	[HW,JOY] Amiga joystick support
464				Map of devices attached to JOY0DAT and JOY1DAT
465				Format: <a>,<b>
466				See also Documentation/input/joystick.txt
468		analog.map=	[HW,JOY] Analog joystick and gamepad support
469				Specifies type or capabilities of an analog joystick
470				connected to one of 16 gameports
471				Format: <type1>,<type2>,..<type16>
473		apc=		[HW,SPARC]
474				Power management functions (SPARCstation-4/5 + deriv.)
475				Format: noidle
476				Disable APC CPU standby support. SPARCstation-Fox does
477				not play well with APC CPU idle - disable it if you have
478				APC and your system crashes randomly.
480		apic=		[APIC,X86-32] Advanced Programmable Interrupt Controller
481				Change the output verbosity whilst booting
482				Format: { quiet (default) | verbose | debug }
483				Change the amount of debugging information output
484				when initialising the APIC and IO-APIC components.
486		apic_extnmi=	[APIC,X86] External NMI delivery setting
487				Format: { bsp (default) | all | none }
488				bsp:  External NMI is delivered only to CPU 0
489				all:  External NMIs are broadcast to all CPUs as a
490				      backup of CPU 0
491				none: External NMI is masked for all CPUs. This is
492				      useful so that a dump capture kernel won't be
493				      shot down by NMI
495		autoconf=	[IPV6]
496				See Documentation/networking/ipv6.txt.
498		show_lapic=	[APIC,X86] Advanced Programmable Interrupt Controller
499				Limit apic dumping. The parameter defines the maximal
500				number of local apics being dumped. Also it is possible
501				to set it to "all" by meaning -- no limit here.
502				Format: { 1 (default) | 2 | ... | all }.
503				The parameter valid if only apic=debug or
504				apic=verbose is specified.
505				Example: apic=debug show_lapic=all
507		apm=		[APM] Advanced Power Management
508				See header of arch/x86/kernel/apm_32.c.
510		arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
511				Format: <io>,<irq>,<nodeID>
513		ataflop=	[HW,M68k]
515		atarimouse=	[HW,MOUSE] Atari Mouse
517		atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
518				EzKey and similar keyboards
520		atkbd.reset=	[HW] Reset keyboard during initialization
522		atkbd.set=	[HW] Select keyboard code set
523				Format: <int> (2 = AT (default), 3 = PS/2)
525		atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
526				keyboards
528		atkbd.softraw=	[HW] Choose between synthetic and real raw mode
529				Format: <bool> (0 = real, 1 = synthetic (default))
531		atkbd.softrepeat= [HW]
532				Use software keyboard repeat
534		audit=		[KNL] Enable the audit sub-system
535				Format: { "0" | "1" } (0 = disabled, 1 = enabled)
536				0 - kernel audit is disabled and can not be enabled
537				    until the next reboot
538				unset - kernel audit is initialized but disabled and
539				    will be fully enabled by the userspace auditd.
540				1 - kernel audit is initialized and partially enabled,
541				    storing at most audit_backlog_limit messages in
542				    RAM until it is fully enabled by the userspace
543				    auditd.
544				Default: unset
546		audit_backlog_limit= [KNL] Set the audit queue size limit.
547				Format: <int> (must be >=0)
548				Default: 64
550		bau=		[X86_UV] Enable the BAU on SGI UV.  The default
551				behavior is to disable the BAU (i.e. bau=0).
552				Format: { "0" | "1" }
553				0 - Disable the BAU.
554				1 - Enable the BAU.
555				unset - Disable the BAU.
557		baycom_epp=	[HW,AX25]
558				Format: <io>,<mode>
560		baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
561				Format: <io>,<mode>
562				See header of drivers/net/hamradio/baycom_par.c.
564		baycom_ser_fdx=	[HW,AX25]
565				BayCom Serial Port AX.25 Modem (Full Duplex Mode)
566				Format: <io>,<irq>,<mode>[,<baud>]
567				See header of drivers/net/hamradio/baycom_ser_fdx.c.
569		baycom_ser_hdx=	[HW,AX25]
570				BayCom Serial Port AX.25 Modem (Half Duplex Mode)
571				Format: <io>,<irq>,<mode>
572				See header of drivers/net/hamradio/baycom_ser_hdx.c.
574		blkdevparts=	Manual partition parsing of block device(s) for
575				embedded devices based on command line input.
576				See Documentation/block/cmdline-partition.txt
578		boot_delay=	Milliseconds to delay each printk during boot.
579				Values larger than 10 seconds (10000) are changed to
580				no delay (0).
581				Format: integer
583		bootmem_debug	[KNL] Enable bootmem allocator debug messages.
585		bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
586		bttv.radio=	Most important insmod options are available as
587				kernel args too.
588		bttv.pll=	See Documentation/video4linux/bttv/Insmod-options
589		bttv.tuner=
591		bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
592				firmware feature for flushing multiple hpte entries
593				at a time.
595		c101=		[NET] Moxa C101 synchronous serial card
597		cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
598				Sometimes CPU hardware bugs make them report the cache
599				size incorrectly. The kernel will attempt work arounds
600				to fix known problems, but for some CPUs it is not
601				possible to determine what the correct size should be.
602				This option provides an override for these situations.
604		ca_keys=	[KEYS] This parameter identifies a specific key(s) on
605				the system trusted keyring to be used for certificate
606				trust validation.
607				format: { id:<keyid> | builtin }
609		cca=		[MIPS] Override the kernel pages' cache coherency
610				algorithm.  Accepted values range from 0 to 7
611				inclusive. See arch/mips/include/asm/pgtable-bits.h
612				for platform specific values (SB1, Loongson3 and
613				others).
615		ccw_timeout_log [S390]
616				See Documentation/s390/CommonIO for details.
618		cgroup_disable= [KNL] Disable a particular controller
619				Format: {name of the controller(s) to disable}
620				The effects of cgroup_disable=foo are:
621				- foo isn't auto-mounted if you mount all cgroups in
622				  a single hierarchy
623				- foo isn't visible as an individually mountable
624				  subsystem
625				{Currently only "memory" controller deal with this and
626				cut the overhead, others just disable the usage. So
627				only cgroup_disable=memory is actually worthy}
629		cgroup_no_v1=	[KNL] Disable one, multiple, all cgroup controllers in v1
630				Format: { controller[,controller...] | "all" }
631				Like cgroup_disable, but only applies to cgroup v1;
632				the blacklisted controllers remain available in cgroup2.
634		cgroup.memory=	[KNL] Pass options to the cgroup memory controller.
635				Format: <string>
636				nosocket -- Disable socket memory accounting.
637				nokmem -- Disable kernel memory accounting.
639		checkreqprot	[SELINUX] Set initial checkreqprot flag value.
640				Format: { "0" | "1" }
641				See security/selinux/Kconfig help text.
642				0 -- check protection applied by kernel (includes
643					any implied execute protection).
644				1 -- check protection requested by application.
645				Default value is set via a kernel config option.
646				Value can be changed at runtime via
647					/selinux/checkreqprot.
649		cio_ignore=	[S390]
650				See Documentation/s390/CommonIO for details.
651		clk_ignore_unused
652				[CLK]
653				Prevents the clock framework from automatically gating
654				clocks that have not been explicitly enabled by a Linux
655				device driver but are enabled in hardware at reset or
656				by the bootloader/firmware. Note that this does not
657				force such clocks to be always-on nor does it reserve
658				those clocks in any way. This parameter is useful for
659				debug and development, but should not be needed on a
660				platform with proper driver support.  For more
661				information, see Documentation/clk.txt.
663		clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
664				[Deprecated]
665				Forces specified clocksource (if available) to be used
666				when calculating gettimeofday(). If specified
667				clocksource is not available, it defaults to PIT.
668				Format: { pit | tsc | cyclone | pmtmr }
670		clocksource=	Override the default clocksource
671				Format: <string>
672				Override the default clocksource and use the clocksource
673				with the name specified.
674				Some clocksource names to choose from, depending on
675				the platform:
676				[all] jiffies (this is the base, fallback clocksource)
677				[ACPI] acpi_pm
678				[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
679					pxa_timer,timer3,32k_counter,timer0_1
680				[AVR32] avr32
681				[X86-32] pit,hpet,tsc;
682					scx200_hrt on Geode; cyclone on IBM x440
683				[MIPS] MIPS
684				[PARISC] cr16
685				[S390] tod
686				[SH] SuperH
687				[SPARC64] tick
688				[X86-64] hpet,tsc
690		clearcpuid=BITNUM [X86]
691				Disable CPUID feature X for the kernel. See
692				arch/x86/include/asm/cpufeatures.h for the valid bit
693				numbers. Note the Linux specific bits are not necessarily
694				stable over kernel options, but the vendor specific
695				ones should be.
696				Also note that user programs calling CPUID directly
697				or using the feature without checking anything
698				will still see it. This just prevents it from
699				being used by the kernel or shown in /proc/cpuinfo.
700				Also note the kernel might malfunction if you disable
701				some critical bits.
703		cma=nn[MG]@[start[MG][-end[MG]]]
704				[ARM,X86,KNL]
705				Sets the size of kernel global memory area for
706				contiguous memory allocations and optionally the
707				placement constraint by the physical address range of
708				memory allocations. A value of 0 disables CMA
709				altogether. For more information, see
710				include/linux/dma-contiguous.h
712		cmo_free_hint=	[PPC] Format: { yes | no }
713				Specify whether pages are marked as being inactive
714				when they are freed.  This is used in CMO environments
715				to determine OS memory pressure for page stealing by
716				a hypervisor.
717				Default: yes
719		coherent_pool=nn[KMG]	[ARM,KNL]
720				Sets the size of memory pool for coherent, atomic dma
721				allocations, by default set to 256K.
723		code_bytes	[X86] How many bytes of object code to print
724				in an oops report.
725				Range: 0 - 8192
726				Default: 64
728		com20020=	[HW,NET] ARCnet - COM20020 chipset
729				Format:
730				<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
732		com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
733				Format: <io>[,<irq>]
735		com90xx=	[HW,NET]
736				ARCnet - COM90xx chipset (memory-mapped buffers)
737				Format: <io>[,<irq>[,<memstart>]]
739		condev=		[HW,S390] console device
740		conmode=
742		console=	[KNL] Output console device and options.
744			tty<n>	Use the virtual console device <n>.
746			ttyS<n>[,options]
747			ttyUSB0[,options]
748				Use the specified serial port.  The options are of
749				the form "bbbbpnf", where "bbbb" is the baud rate,
750				"p" is parity ("n", "o", or "e"), "n" is number of
751				bits, and "f" is flow control ("r" for RTS or
752				omit it).  Default is "9600n8".
754				See Documentation/serial-console.txt for more
755				information.  See
756				Documentation/networking/netconsole.txt for an
757				alternative.
759			uart[8250],io,<addr>[,options]
760			uart[8250],mmio,<addr>[,options]
761			uart[8250],mmio16,<addr>[,options]
762			uart[8250],mmio32,<addr>[,options]
763			uart[8250],0x<addr>[,options]
764				Start an early, polled-mode console on the 8250/16550
765				UART at the specified I/O port or MMIO address,
766				switching to the matching ttyS device later.
767				MMIO inter-register address stride is either 8-bit
768				(mmio), 16-bit (mmio16), or 32-bit (mmio32).
769				If none of [io|mmio|mmio16|mmio32], <addr> is assumed
770				to be equivalent to 'mmio'. 'options' are specified in
771				the same format described for ttyS above; if unspecified,
772				the h/w is not re-initialized.
774			hvc<n>	Use the hypervisor console device <n>. This is for
775				both Xen and PowerPC hypervisors.
777	                If the device connected to the port is not a TTY but a braille
778	                device, prepend "brl," before the device type, for instance
779				console=brl,ttyS0
780			For now, only VisioBraille is supported.
782		consoleblank=	[KNL] The console blank (screen saver) timeout in
783				seconds. Defaults to 10*60 = 10mins. A value of 0
784				disables the blank timer.
786		coredump_filter=
787				[KNL] Change the default value for
788				/proc/<pid>/coredump_filter.
789				See also Documentation/filesystems/proc.txt.
791		cpuidle.off=1	[CPU_IDLE]
792				disable the cpuidle sub-system
794		cpu_init_udelay=N
795				[X86] Delay for N microsec between assert and de-assert
796				of APIC INIT to start processors.  This delay occurs
797				on every CPU online, such as boot, and resume from suspend.
798				Default: 10000
800		cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
801				Format:
802				<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
804		crashkernel=size[KMG][@offset[KMG]]
805				[KNL] Using kexec, Linux can switch to a 'crash kernel'
806				upon panic. This parameter reserves the physical
807				memory region [offset, offset + size] for that kernel
808				image. If '@offset' is omitted, then a suitable offset
809				is selected automatically. Check
810				Documentation/kdump/kdump.txt for further details.
812		crashkernel=range1:size1[,range2:size2,...][@offset]
813				[KNL] Same as above, but depends on the memory
814				in the running system. The syntax of range is
815				start-[end] where start and end are both
816				a memory unit (amount[KMG]). See also
817				Documentation/kdump/kdump.txt for an example.
819		crashkernel=size[KMG],high
820				[KNL, x86_64] range could be above 4G. Allow kernel
821				to allocate physical memory region from top, so could
822				be above 4G if system have more than 4G ram installed.
823				Otherwise memory region will be allocated below 4G, if
824				available.
825				It will be ignored if crashkernel=X is specified.
826		crashkernel=size[KMG],low
827				[KNL, x86_64] range under 4G. When crashkernel=X,high
828				is passed, kernel could allocate physical memory region
829				above 4G, that cause second kernel crash on system
830				that require some amount of low memory, e.g. swiotlb
831				requires at least 64M+32K low memory, also enough extra
832				low memory is needed to make sure DMA buffers for 32-bit
833				devices won't run out. Kernel would try to allocate at
834				at least 256M below 4G automatically.
835				This one let user to specify own low range under 4G
836				for second kernel instead.
837				0: to disable low allocation.
838				It will be ignored when crashkernel=X,high is not used
839				or memory reserved is below 4G.
841		cryptomgr.notests
842	                        [KNL] Disable crypto self-tests
844		cs89x0_dma=	[HW,NET]
845				Format: <dma>
847		cs89x0_media=	[HW,NET]
848				Format: { rj45 | aui | bnc }
850		dasd=		[HW,NET]
851				See header of drivers/s390/block/dasd_devmap.c.
853		db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
854				(one device per port)
855				Format: <port#>,<type>
856				See also Documentation/input/joystick-parport.txt
858		ddebug_query=   [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
859				time. See Documentation/dynamic-debug-howto.txt for
860				details.  Deprecated, see dyndbg.
862		debug		[KNL] Enable kernel debugging (events log level).
864		debug_locks_verbose=
865				[KNL] verbose self-tests
866				Format=<0|1>
867				Print debugging info while doing the locking API
868				self-tests.
869				We default to 0 (no extra messages), setting it to
870				1 will print _a lot_ more information - normally
871				only useful to kernel developers.
873		debug_objects	[KNL] Enable object debugging
875		no_debug_objects
876				[KNL] Disable object debugging
878		debug_guardpage_minorder=
879				[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
880				parameter allows control of the order of pages that will
881				be intentionally kept free (and hence protected) by the
882				buddy allocator. Bigger value increase the probability
883				of catching random memory corruption, but reduce the
884				amount of memory for normal system use. The maximum
885				possible value is MAX_ORDER/2.  Setting this parameter
886				to 1 or 2 should be enough to identify most random
887				memory corruption problems caused by bugs in kernel or
888				driver code when a CPU writes to (or reads from) a
889				random memory location. Note that there exists a class
890				of memory corruptions problems caused by buggy H/W or
891				F/W or by drivers badly programing DMA (basically when
892				memory is written at bus level and the CPU MMU is
893				bypassed) which are not detectable by
894				CONFIG_DEBUG_PAGEALLOC, hence this option will not help
895				tracking down these problems.
897		debug_pagealloc=
898				[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
899				parameter enables the feature at boot time. In
900				default, it is disabled. We can avoid allocating huge
901				chunk of memory for debug pagealloc if we don't enable
902				it at boot time and the system will work mostly same
903				with the kernel built without CONFIG_DEBUG_PAGEALLOC.
904				on: enable the feature
906		debugpat	[X86] Enable PAT debugging
908		decnet.addr=	[HW,NET]
909				Format: <area>[,<node>]
910				See also Documentation/networking/decnet.txt.
912		default_hugepagesz=
913				[same as hugepagesz=] The size of the default
914				HugeTLB page size. This is the size represented by
915				the legacy /proc/ hugepages APIs, used for SHM, and
916				default size when mounting hugetlbfs filesystems.
917				Defaults to the default architecture's huge page size
918				if not specified.
920		dhash_entries=	[KNL]
921				Set number of hash buckets for dentry cache.
923		disable=	[IPV6]
924				See Documentation/networking/ipv6.txt.
926		disable_cpu_apicid= [X86,APIC,SMP]
927				Format: <int>
928				The number of initial APIC ID for the
929				corresponding CPU to be disabled at boot,
930				mostly used for the kdump 2nd kernel to
931				disable BSP to wake up multiple CPUs without
932				causing system reset or hang due to sending
933				INIT from AP to BSP.
935		disable_ddw     [PPC/PSERIES]
936				Disable Dynamic DMA Window support. Use this if
937				to workaround buggy firmware.
939		disable_ipv6=	[IPV6]
940				See Documentation/networking/ipv6.txt.
942		disable_mtrr_cleanup [X86]
943				The kernel tries to adjust MTRR layout from continuous
944				to discrete, to make X server driver able to add WB
945				entry later. This parameter disables that.
947		disable_mtrr_trim [X86, Intel and AMD only]
948				By default the kernel will trim any uncacheable
949				memory out of your available memory pool based on
950				MTRR settings.  This parameter disables that behavior,
951				possibly causing your machine to run very slowly.
953		disable_timer_pin_1 [X86]
954				Disable PIN 1 of APIC timer
955				Can be useful to work around chipset bugs.
957		dis_ucode_ldr	[X86] Disable the microcode loader.
959		dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
960				this option disables the debugging code at boot.
962		dma_debug_entries=<number>
963				This option allows to tune the number of preallocated
964				entries for DMA-API debugging code. One entry is
965				required per DMA-API allocation. Use this if the
966				DMA-API debugging code disables itself because the
967				architectural default is too low.
969		dma_debug_driver=<driver_name>
970				With this option the DMA-API debugging driver
971				filter feature can be enabled at boot time. Just
972				pass the driver to filter for as the parameter.
973				The filter can be disabled or changed to another
974				driver later using sysfs.
976		drm_kms_helper.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
977				Broken monitors, graphic adapters, KVMs and EDIDless
978				panels may send no or incorrect EDID data sets.
979				This parameter allows to specify an EDID data sets
980				in the /lib/firmware directory that are used instead.
981				Generic built-in EDID data sets are used, if one of
982				edid/1024x768.bin, edid/1280x1024.bin,
983				edid/1680x1050.bin, or edid/1920x1080.bin is given
984				and no file with the same name exists. Details and
985				instructions how to build your own EDID data are
986				available in Documentation/EDID/HOWTO.txt. An EDID
987				data set will only be used for a particular connector,
988				if its name and a colon are prepended to the EDID
989				name. Each connector may use a unique EDID data
990				set by separating the files with a comma.  An EDID
991				data set with no connector name will be used for
992				any connectors not explicitly specified.
994		dscc4.setup=	[NET]
996		dyndbg[="val"]		[KNL,DYNAMIC_DEBUG]
997		module.dyndbg[="val"]
998				Enable debug messages at boot time.  See
999				Documentation/dynamic-debug-howto.txt for details.
1001		nompx		[X86] Disables Intel Memory Protection Extensions.
1002				See Documentation/x86/intel_mpx.txt for more
1003				information about the feature.
1005		nopku		[X86] Disable Memory Protection Keys CPU feature found
1006				in some Intel CPUs.
1008		eagerfpu=	[X86]
1009				on	enable eager fpu restore
1010				off	disable eager fpu restore
1011				auto	selects the default scheme, which automatically
1012					enables eagerfpu restore for xsaveopt.
1014		module.async_probe [KNL]
1015				Enable asynchronous probe on this module.
1017		early_ioremap_debug [KNL]
1018				Enable debug messages in early_ioremap support. This
1019				is useful for tracking down temporary early mappings
1020				which are not unmapped.
1022		earlycon=	[KNL] Output early console device and options.
1024				When used with no options, the early console is
1025				determined by the stdout-path property in device
1026				tree's chosen node.
1028			cdns,<addr>
1029				Start an early, polled-mode console on a cadence serial
1030				port at the specified address. The cadence serial port
1031				must already be setup and configured. Options are not
1032				yet supported.
1034			uart[8250],io,<addr>[,options]
1035			uart[8250],mmio,<addr>[,options]
1036			uart[8250],mmio32,<addr>[,options]
1037			uart[8250],mmio32be,<addr>[,options]
1038			uart[8250],0x<addr>[,options]
1039				Start an early, polled-mode console on the 8250/16550
1040				UART at the specified I/O port or MMIO address.
1041				MMIO inter-register address stride is either 8-bit
1042				(mmio) or 32-bit (mmio32 or mmio32be).
1043				If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
1044				to be equivalent to 'mmio'. 'options' are specified
1045				in the same format described for "console=ttyS<n>"; if
1046				unspecified, the h/w is not initialized.
1048			pl011,<addr>
1049			pl011,mmio32,<addr>
1050				Start an early, polled-mode console on a pl011 serial
1051				port at the specified address. The pl011 serial port
1052				must already be setup and configured. Options are not
1053				yet supported.  If 'mmio32' is specified, then only
1054				the driver will use only 32-bit accessors to read/write
1055				the device registers.
1057			meson,<addr>
1058				Start an early, polled-mode console on a meson serial
1059				port at the specified address. The serial port must
1060				already be setup and configured. Options are not yet
1061				supported.
1063			msm_serial,<addr>
1064				Start an early, polled-mode console on an msm serial
1065				port at the specified address. The serial port
1066				must already be setup and configured. Options are not
1067				yet supported.
1069			msm_serial_dm,<addr>
1070				Start an early, polled-mode console on an msm serial
1071				dm port at the specified address. The serial port
1072				must already be setup and configured. Options are not
1073				yet supported.
1075			smh	Use ARM semihosting calls for early console.
1077			s3c2410,<addr>
1078			s3c2412,<addr>
1079			s3c2440,<addr>
1080			s3c6400,<addr>
1081			s5pv210,<addr>
1082			exynos4210,<addr>
1083				Use early console provided by serial driver available
1084				on Samsung SoCs, requires selecting proper type and
1085				a correct base address of the selected UART port. The
1086				serial port must already be setup and configured.
1087				Options are not yet supported.
1089			lpuart,<addr>
1090			lpuart32,<addr>
1091				Use early console provided by Freescale LP UART driver
1092				found on Freescale Vybrid and QorIQ LS1021A processors.
1093				A valid base address must be provided, and the serial
1094				port must already be setup and configured.
1096			armada3700_uart,<addr>
1097				Start an early, polled-mode console on the
1098				Armada 3700 serial port at the specified
1099				address. The serial port must already be setup
1100				and configured. Options are not yet supported.
1102		earlyprintk=	[X86,SH,BLACKFIN,ARM,M68k]
1103				earlyprintk=vga
1104				earlyprintk=efi
1105				earlyprintk=xen
1106				earlyprintk=serial[,ttySn[,baudrate]]
1107				earlyprintk=serial[,0x...[,baudrate]]
1108				earlyprintk=ttySn[,baudrate]
1109				earlyprintk=dbgp[debugController#]
1110				earlyprintk=pciserial,bus:device.function[,baudrate]
1112				earlyprintk is useful when the kernel crashes before
1113				the normal console is initialized. It is not enabled by
1114				default because it has some cosmetic problems.
1116				Append ",keep" to not disable it when the real console
1117				takes over.
1119				Only one of vga, efi, serial, or usb debug port can
1120				be used at a time.
1122				Currently only ttyS0 and ttyS1 may be specified by
1123				name.  Other I/O ports may be explicitly specified
1124				on some architectures (x86 and arm at least) by
1125				replacing ttySn with an I/O port address, like this:
1126					earlyprintk=serial,0x1008,115200
1127				You can find the port for a given device in
1128				/proc/tty/driver/serial:
1129					2: uart:ST16650V2 port:00001008 irq:18 ...
1131				Interaction with the standard serial driver is not
1132				very good.
1134				The VGA and EFI output is eventually overwritten by
1135				the real console.
1137				The xen output can only be used by Xen PV guests.
1139		edac_report=	[HW,EDAC] Control how to report EDAC event
1140				Format: {"on" | "off" | "force"}
1141				on: enable EDAC to report H/W event. May be overridden
1142				by other higher priority error reporting module.
1143				off: disable H/W event reporting through EDAC.
1144				force: enforce the use of EDAC to report H/W event.
1145				default: on.
1147		ekgdboc=	[X86,KGDB] Allow early kernel console debugging
1148				ekgdboc=kbd
1150				This is designed to be used in conjunction with
1151				the boot argument: earlyprintk=vga
1153		edd=		[EDD]
1154				Format: {"off" | "on" | "skip[mbr]"}
1156		efi=		[EFI]
1157				Format: { "old_map", "nochunk", "noruntime", "debug" }
1158				old_map [X86-64]: switch to the old ioremap-based EFI
1159				runtime services mapping. 32-bit still uses this one by
1160				default.
1161				nochunk: disable reading files in "chunks" in the EFI
1162				boot stub, as chunking can cause problems with some
1163				firmware implementations.
1164				noruntime : disable EFI runtime services support
1165				debug: enable misc debug output
1167		efi_no_storage_paranoia [EFI; X86]
1168				Using this parameter you can use more than 50% of
1169				your efi variable storage. Use this parameter only if
1170				you are really sure that your UEFI does sane gc and
1171				fulfills the spec otherwise your board may brick.
1173		efi_fake_mem=	nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86]
1174				Add arbitrary attribute to specific memory range by
1175				updating original EFI memory map.
1176				Region of memory which aa attribute is added to is
1177				from ss to ss+nn.
1178				If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
1179				is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
1180				attribute is added to range 0x100000000-0x180000000 and
1181				0x10a0000000-0x1120000000.
1183				Using this parameter you can do debugging of EFI memmap
1184				related feature. For example, you can do debugging of
1185				Address Range Mirroring feature even if your box
1186				doesn't support it.
1188		eisa_irq_edge=	[PARISC,HW]
1189				See header of drivers/parisc/eisa.c.
1191		elanfreq=	[X86-32]
1192				See comment before function elanfreq_setup() in
1193				arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1195		elevator=	[IOSCHED]
1196				Format: {"cfq" | "deadline" | "noop"}
1197				See Documentation/block/cfq-iosched.txt and
1198				Documentation/block/deadline-iosched.txt for details.
1200		elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
1201				Specifies physical address of start of kernel core
1202				image elf header and optionally the size. Generally
1203				kexec loader will pass this option to capture kernel.
1204				See Documentation/kdump/kdump.txt for details.
1206		enable_mtrr_cleanup [X86]
1207				The kernel tries to adjust MTRR layout from continuous
1208				to discrete, to make X server driver able to add WB
1209				entry later. This parameter enables that.
1211		enable_timer_pin_1 [X86]
1212				Enable PIN 1 of APIC timer
1213				Can be useful to work around chipset bugs
1214				(in particular on some ATI chipsets).
1215				The kernel tries to set a reasonable default.
1217		enforcing	[SELINUX] Set initial enforcing status.
1218				Format: {"0" | "1"}
1219				See security/selinux/Kconfig help text.
1220				0 -- permissive (log only, no denials).
1221				1 -- enforcing (deny and log).
1222				Default value is 0.
1223				Value can be changed at runtime via /selinux/enforce.
1225		erst_disable	[ACPI]
1226				Disable Error Record Serialization Table (ERST)
1227				support.
1229		ether=		[HW,NET] Ethernet cards parameters
1230				This option is obsoleted by the "netdev=" option, which
1231				has equivalent usage. See its documentation for details.
1233		evm=		[EVM]
1234				Format: { "fix" }
1235				Permit 'security.evm' to be updated regardless of
1236				current integrity status.
1238		failslab=
1239		fail_page_alloc=
1240		fail_make_request=[KNL]
1241				General fault injection mechanism.
1242				Format: <interval>,<probability>,<space>,<times>
1243				See also Documentation/fault-injection/.
1245		floppy=		[HW]
1246				See Documentation/blockdev/floppy.txt.
1248		force_pal_cache_flush
1249				[IA-64] Avoid check_sal_cache_flush which may hang on
1250				buggy SAL_CACHE_FLUSH implementations. Using this
1251				parameter will force ia64_sal_cache_flush to call
1252				ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
1254		forcepae [X86-32]
1255				Forcefully enable Physical Address Extension (PAE).
1256				Many Pentium M systems disable PAE but may have a
1257				functionally usable PAE implementation.
1258				Warning: use of this parameter will taint the kernel
1259				and may cause unknown problems.
1261		ftrace=[tracer]
1262				[FTRACE] will set and start the specified tracer
1263				as early as possible in order to facilitate early
1264				boot debugging.
1266		ftrace_dump_on_oops[=orig_cpu]
1267				[FTRACE] will dump the trace buffers on oops.
1268				If no parameter is passed, ftrace will dump
1269				buffers of all CPUs, but if you pass orig_cpu, it will
1270				dump only the buffer of the CPU that triggered the
1271				oops.
1273		ftrace_filter=[function-list]
1274				[FTRACE] Limit the functions traced by the function
1275				tracer at boot up. function-list is a comma separated
1276				list of functions. This list can be changed at run
1277				time by the set_ftrace_filter file in the debugfs
1278				tracing directory.
1280		ftrace_notrace=[function-list]
1281				[FTRACE] Do not trace the functions specified in
1282				function-list. This list can be changed at run time
1283				by the set_ftrace_notrace file in the debugfs
1284				tracing directory.
1286		ftrace_graph_filter=[function-list]
1287				[FTRACE] Limit the top level callers functions traced
1288				by the function graph tracer at boot up.
1289				function-list is a comma separated list of functions
1290				that can be changed at run time by the
1291				set_graph_function file in the debugfs tracing directory.
1293		ftrace_graph_notrace=[function-list]
1294				[FTRACE] Do not trace from the functions specified in
1295				function-list.  This list is a comma separated list of
1296				functions that can be changed at run time by the
1297				set_graph_notrace file in the debugfs tracing directory.
1299		gamecon.map[2|3]=
1300				[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
1301				support via parallel port (up to 5 devices per port)
1302				Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1303				See also Documentation/input/joystick-parport.txt
1305		gamma=		[HW,DRM]
1307		gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
1308				Format: off | on
1309				default: on
1311		gcov_persist=	[GCOV] When non-zero (default), profiling data for
1312				kernel modules is saved and remains accessible via
1313				debugfs, even when the module is unloaded/reloaded.
1314				When zero, profiling data is discarded and associated
1315				debugfs files are removed at module unload time.
1317		gpt		[EFI] Forces disk with valid GPT signature but
1318				invalid Protective MBR to be treated as GPT. If the
1319				primary GPT is corrupted, it enables the backup/alternate
1320				GPT to be used instead.
1322		grcan.enable0=	[HW] Configuration of physical interface 0. Determines
1323				the "Enable 0" bit of the configuration register.
1324				Format: 0 | 1
1325				Default: 0
1326		grcan.enable1=	[HW] Configuration of physical interface 1. Determines
1327				the "Enable 0" bit of the configuration register.
1328				Format: 0 | 1
1329				Default: 0
1330		grcan.select=	[HW] Select which physical interface to use.
1331				Format: 0 | 1
1332				Default: 0
1333		grcan.txsize=	[HW] Sets the size of the tx buffer.
1334				Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
1335				Default: 1024
1336		grcan.rxsize=	[HW] Sets the size of the rx buffer.
1337				Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
1338				Default: 1024
1340		hardlockup_all_cpu_backtrace=
1341				[KNL] Should the hard-lockup detector generate
1342				backtraces on all cpus.
1343				Format: <integer>
1345		hashdist=	[KNL,NUMA] Large hashes allocated during boot
1346				are distributed across NUMA nodes.  Defaults on
1347				for 64-bit NUMA, off otherwise.
1348				Format: 0 | 1 (for off | on)
1350		hcl=		[IA-64] SGI's Hardware Graph compatibility layer
1352		hd=		[EIDE] (E)IDE hard drive subsystem geometry
1353				Format: <cyl>,<head>,<sect>
1355		hest_disable	[ACPI]
1356				Disable Hardware Error Source Table (HEST) support;
1357				corresponding firmware-first mode error processing
1358				logic will be disabled.
1360		highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
1361				size of <nn>. This works even on boxes that have no
1362				highmem otherwise. This also works to reduce highmem
1363				size on bigger boxes.
1365		highres=	[KNL] Enable/disable high resolution timer mode.
1366				Valid parameters: "on", "off"
1367				Default: "on"
1369		hisax=		[HW,ISDN]
1370				See Documentation/isdn/README.HiSax.
1372		hlt		[BUGS=ARM,SH]
1374		hpet=		[X86-32,HPET] option to control HPET usage
1375				Format: { enable (default) | disable | force |
1376					verbose }
1377				disable: disable HPET and use PIT instead
1378				force: allow force enabled of undocumented chips (ICH4,
1379					VIA, nVidia)
1380				verbose: show contents of HPET registers during setup
1382		hpet_mmap=	[X86, HPET_MMAP] Allow userspace to mmap HPET
1383				registers.  Default set by CONFIG_HPET_MMAP_DEFAULT.
1385		hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
1386		hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
1387				On x86-64 and powerpc, this option can be specified
1388				multiple times interleaved with hugepages= to reserve
1389				huge pages of different sizes. Valid pages sizes on
1390				x86-64 are 2M (when the CPU supports "pse") and 1G
1391				(when the CPU supports the "pdpe1gb" cpuinfo flag).
1393		hvc_iucv=	[S390] Number of z/VM IUCV hypervisor console (HVC)
1394				       terminal devices. Valid values: 0..8
1395		hvc_iucv_allow=	[S390] Comma-separated list of z/VM user IDs.
1396				       If specified, z/VM IUCV HVC accepts connections
1397				       from listed z/VM user IDs only.
1399		hwthread_map=	[METAG] Comma-separated list of Linux cpu id to
1400				        hardware thread id mappings.
1401					Format: <cpu>:<hwthread>
1403		keep_bootcon	[KNL]
1404				Do not unregister boot console at start. This is only
1405				useful for debugging when something happens in the window
1406				between unregistering the boot console and initializing
1407				the real console.
1409		i2c_bus=	[HW] Override the default board specific I2C bus speed
1410				     or register an additional I2C bus that is not
1411				     registered from board initialization code.
1412				     Format:
1413				     <bus_id>,<clkrate>
1415		i8042.debug	[HW] Toggle i8042 debug mode
1416		i8042.unmask_kbd_data
1417				[HW] Enable printing of interrupt data from the KBD port
1418				     (disabled by default, and as a pre-condition
1419				     requires that i8042.debug=1 be enabled)
1420		i8042.direct	[HW] Put keyboard port into non-translated mode
1421		i8042.dumbkbd	[HW] Pretend that controller can only read data from
1422				     keyboard and cannot control its state
1423				     (Don't attempt to blink the leds)
1424		i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
1425		i8042.nokbd	[HW] Don't check/create keyboard port
1426		i8042.noloop	[HW] Disable the AUX Loopback command while probing
1427				     for the AUX port
1428		i8042.nomux	[HW] Don't check presence of an active multiplexing
1429				     controller
1430		i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1431				     controllers
1432		i8042.notimeout	[HW] Ignore timeout condition signalled by controller
1433		i8042.reset	[HW] Reset the controller during init and cleanup
1434		i8042.unlock	[HW] Unlock (ignore) the keylock
1435		i8042.kbdreset  [HW] Reset device connected to KBD port
1437		i810=		[HW,DRM]
1439		i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
1440				indicates that the driver is running on unsupported
1441				hardware.
1442		i8k.force	[HW] Activate i8k driver even if SMM BIOS signature
1443				does not match list of supported models.
1444		i8k.power_status
1445				[HW] Report power status in /proc/i8k
1446				(disabled by default)
1447		i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN
1448				capability is set.
1450		i915.invert_brightness=
1451				[DRM] Invert the sense of the variable that is used to
1452				set the brightness of the panel backlight. Normally a
1453				brightness value of 0 indicates backlight switched off,
1454				and the maximum of the brightness value sets the backlight
1455				to maximum brightness. If this parameter is set to 0
1456				(default) and the machine requires it, or this parameter
1457				is set to 1, a brightness value of 0 sets the backlight
1458				to maximum brightness, and the maximum of the brightness
1459				value switches the backlight off.
1460				-1 -- never invert brightness
1461				 0 -- machine default
1462				 1 -- force brightness inversion
1464		icn=		[HW,ISDN]
1465				Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1467		ide-core.nodma=	[HW] (E)IDE subsystem
1468				Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1469				.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1470				.cdrom .chs .ignore_cable are additional options
1471				See Documentation/ide/ide.txt.
1473		ide-generic.probe-mask= [HW] (E)IDE subsystem
1474				Format: <int>
1475				Probe mask for legacy ISA IDE ports.  Depending on
1476				platform up to 6 ports are supported, enabled by
1477				setting corresponding bits in the mask to 1.  The
1478				default value is 0x0, which has a special meaning.
1479				On systems that have PCI, it triggers scanning the
1480				PCI bus for the first and the second port, which
1481				are then probed.  On systems without PCI the value
1482				of 0x0 enables probing the two first ports as if it
1483				was 0x3.
1485		ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1486				Claim all unknown PCI IDE storage controllers.
1488		idle=		[X86]
1489				Format: idle=poll, idle=halt, idle=nomwait
1490				Poll forces a polling idle loop that can slightly
1491				improve the performance of waking up a idle CPU, but
1492				will use a lot of power and make the system run hot.
1493				Not recommended.
1494				idle=halt: Halt is forced to be used for CPU idle.
1495				In such case C2/C3 won't be used again.
1496				idle=nomwait: Disable mwait for CPU C-states
1498		ieee754=	[MIPS] Select IEEE Std 754 conformance mode
1499				Format: { strict | legacy | 2008 | relaxed }
1500				Default: strict
1502				Choose which programs will be accepted for execution
1503				based on the IEEE 754 NaN encoding(s) supported by
1504				the FPU and the NaN encoding requested with the value
1505				of an ELF file header flag individually set by each
1506				binary.  Hardware implementations are permitted to
1507				support either or both of the legacy and the 2008 NaN
1508				encoding mode.
1510				Available settings are as follows:
1511				strict	accept binaries that request a NaN encoding
1512					supported by the FPU
1513				legacy	only accept legacy-NaN binaries, if supported
1514					by the FPU
1515				2008	only accept 2008-NaN binaries, if supported
1516					by the FPU
1517				relaxed	accept any binaries regardless of whether
1518					supported by the FPU
1520				The FPU emulator is always able to support both NaN
1521				encodings, so if no FPU hardware is present or it has
1522				been disabled with 'nofpu', then the settings of
1523				'legacy' and '2008' strap the emulator accordingly,
1524				'relaxed' straps the emulator for both legacy-NaN and
1525				2008-NaN, whereas 'strict' enables legacy-NaN only on
1526				legacy processors and both NaN encodings on MIPS32 or
1527				MIPS64 CPUs.
1529				The setting for ABS.fmt/NEG.fmt instruction execution
1530				mode generally follows that for the NaN encoding,
1531				except where unsupported by hardware.
1533		ignore_loglevel	[KNL]
1534				Ignore loglevel setting - this will print /all/
1535				kernel messages to the console. Useful for debugging.
1536				We also add it as printk module parameter, so users
1537				could change it dynamically, usually by
1538				/sys/module/printk/parameters/ignore_loglevel.
1540		ignore_rlimit_data
1541				Ignore RLIMIT_DATA setting for data mappings,
1542				print warning at first misuse.  Can be changed via
1543				/sys/module/kernel/parameters/ignore_rlimit_data.
1545		ihash_entries=	[KNL]
1546				Set number of hash buckets for inode cache.
1548		ima_appraise=	[IMA] appraise integrity measurements
1549				Format: { "off" | "enforce" | "fix" | "log" }
1550				default: "enforce"
1552		ima_appraise_tcb [IMA]
1553				The builtin appraise policy appraises all files
1554				owned by uid=0.
1556		ima_hash=	[IMA]
1557				Format: { md5 | sha1 | rmd160 | sha256 | sha384
1558					   | sha512 | ... }
1559				default: "sha1"
1561				The list of supported hash algorithms is defined
1562				in crypto/hash_info.h.
1564		ima_policy=	[IMA]
1565				The builtin measurement policy to load during IMA
1566				setup.  Specyfing "tcb" as the value, measures all
1567				programs exec'd, files mmap'd for exec, and all files
1568				opened with the read mode bit set by either the
1569				effective uid (euid=0) or uid=0.
1570				Format: "tcb"
1572		ima_tcb		[IMA] Deprecated.  Use ima_policy= instead.
1573				Load a policy which meets the needs of the Trusted
1574				Computing Base.  This means IMA will measure all
1575				programs exec'd, files mmap'd for exec, and all files
1576				opened for read by uid=0.
1578		ima_template=   [IMA]
1579				Select one of defined IMA measurements template formats.
1580				Formats: { "ima" | "ima-ng" | "ima-sig" }
1581				Default: "ima-ng"
1583		ima_template_fmt=
1584		                [IMA] Define a custom template format.
1585				Format: { "field1|...|fieldN" }
1587		ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
1588				Format: <min_file_size>
1589				Set the minimal file size for using asynchronous hash.
1590				If left unspecified, ahash usage is disabled.
1592				ahash performance varies for different data sizes on
1593				different crypto accelerators. This option can be used
1594				to achieve the best performance for a particular HW.
1596		ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
1597				Format: <bufsize>
1598				Set hashing buffer size. Default: 4k.
1600				ahash performance varies for different chunk sizes on
1601				different crypto accelerators. This option can be used
1602				to achieve best performance for particular HW.
1604		init=		[KNL]
1605				Format: <full_path>
1606				Run specified binary instead of /sbin/init as init
1607				process.
1609		initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
1610				for working out where the kernel is dying during
1611				startup.
1613		initcall_blacklist=  [KNL] Do not execute a comma-separated list of
1614				initcall functions.  Useful for debugging built-in
1615				modules and initcalls.
1617		initrd=		[BOOT] Specify the location of the initial ramdisk
1619		inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
1620				Format: <irq>
1622		int_pln_enable  [x86] Enable power limit notification interrupt
1624		integrity_audit=[IMA]
1625				Format: { "0" | "1" }
1626				0 -- basic integrity auditing messages. (Default)
1627				1 -- additional integrity auditing messages.
1629		intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
1630			on
1631				Enable intel iommu driver.
1632			off
1633				Disable intel iommu driver.
1634			igfx_off [Default Off]
1635				By default, gfx is mapped as normal device. If a gfx
1636				device has a dedicated DMAR unit, the DMAR unit is
1637				bypassed by not enabling DMAR with this option. In
1638				this case, gfx device will use physical address for
1639				DMA.
1640			forcedac [x86_64]
1641				With this option iommu will not optimize to look
1642				for io virtual address below 32-bit forcing dual
1643				address cycle on pci bus for cards supporting greater
1644				than 32-bit addressing. The default is to look
1645				for translation below 32-bit and if not available
1646				then look in the higher range.
1647			strict [Default Off]
1648				With this option on every unmap_single operation will
1649				result in a hardware IOTLB flush operation as opposed
1650				to batching them for performance.
1651			sp_off [Default Off]
1652				By default, super page will be supported if Intel IOMMU
1653				has the capability. With this option, super page will
1654				not be supported.
1655			ecs_off [Default Off]
1656				By default, extended context tables will be supported if
1657				the hardware advertises that it has support both for the
1658				extended tables themselves, and also PASID support. With
1659				this option set, extended tables will not be used even
1660				on hardware which claims to support them.
1662		intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
1663				0	disables intel_idle and fall back on acpi_idle.
1664				1 to 6	specify maximum depth of C-state.
1666		intel_pstate=  [X86]
1667			       disable
1668			         Do not enable intel_pstate as the default
1669			         scaling driver for the supported processors
1670			       force
1671				 Enable intel_pstate on systems that prohibit it by default
1672				 in favor of acpi-cpufreq. Forcing the intel_pstate driver
1673				 instead of acpi-cpufreq may disable platform features, such
1674				 as thermal controls and power capping, that rely on ACPI
1675				 P-States information being indicated to OSPM and therefore
1676				 should be used with caution. This option does not work with
1677				 processors that aren't supported by the intel_pstate driver
1678				 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
1679			       no_hwp
1680			         Do not enable hardware P state control (HWP)
1681				 if available.
1682			hwp_only
1683				Only load intel_pstate on systems which support
1684				hardware P state control (HWP) if available.
1685			support_acpi_ppc
1686				Enforce ACPI _PPC performance limits. If the Fixed ACPI
1687				Description Table, specifies preferred power management
1688				profile as "Enterprise Server" or "Performance Server",
1689				then this feature is turned on by default.
1691		intremap=	[X86-64, Intel-IOMMU]
1692				on	enable Interrupt Remapping (default)
1693				off	disable Interrupt Remapping
1694				nosid	disable Source ID checking
1695				no_x2apic_optout
1696					BIOS x2APIC opt-out request will be ignored
1697				nopost	disable Interrupt Posting
1699		iomem=		Disable strict checking of access to MMIO memory
1700			strict	regions from userspace.
1701			relaxed
1703		iommu=		[x86]
1704			off
1705			force
1706			noforce
1707			biomerge
1708			panic
1709			nopanic
1710			merge
1711			nomerge
1712			forcesac
1713			soft
1714			pt		[x86, IA-64]
1715			nobypass	[PPC/POWERNV]
1716				Disable IOMMU bypass, using IOMMU for PCI devices.
1719		io7=		[HW] IO7 for Marvel based alpha systems
1720				See comment before marvel_specify_io7 in
1721				arch/alpha/kernel/core_marvel.c.
1723		io_delay=	[X86] I/O delay method
1724			0x80
1725				Standard port 0x80 based delay
1726			0xed
1727				Alternate port 0xed based delay (needed on some systems)
1728			udelay
1729				Simple two microseconds delay
1730			none
1731				No delay
1733		ip=		[IP_PNP]
1734				See Documentation/filesystems/nfs/nfsroot.txt.
1736		irqaffinity=	[SMP] Set the default irq affinity mask
1737				Format:
1738				<cpu number>,...,<cpu number>
1739				or
1740				<cpu number>-<cpu number>
1741				(must be a positive range in ascending order)
1742				or a mixture
1743				<cpu number>,...,<cpu number>-<cpu number>
1745		irqfixup	[HW]
1746				When an interrupt is not handled search all handlers
1747				for it. Intended to get systems with badly broken
1748				firmware running.
1750		irqpoll		[HW]
1751				When an interrupt is not handled search all handlers
1752				for it. Also check all handlers each timer
1753				interrupt. Intended to get systems with badly broken
1754				firmware running.
1756		isapnp=		[ISAPNP]
1757				Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1759		isolcpus=	[KNL,SMP] Isolate CPUs from the general scheduler.
1760				Format:
1761				<cpu number>,...,<cpu number>
1762				or
1763				<cpu number>-<cpu number>
1764				(must be a positive range in ascending order)
1765				or a mixture
1766				<cpu number>,...,<cpu number>-<cpu number>
1768				This option can be used to specify one or more CPUs
1769				to isolate from the general SMP balancing and scheduling
1770				algorithms. You can move a process onto or off an
1771				"isolated" CPU via the CPU affinity syscalls or cpuset.
1772				<cpu number> begins at 0 and the maximum value is
1773				"number of CPUs in system - 1".
1775				This option is the preferred way to isolate CPUs. The
1776				alternative -- manually setting the CPU mask of all
1777				tasks in the system -- can cause problems and
1778				suboptimal load balancer performance.
1780		iucv=		[HW,NET]
1782		ivrs_ioapic	[HW,X86_64]
1783				Provide an override to the IOAPIC-ID<->DEVICE-ID
1784				mapping provided in the IVRS ACPI table. For
1785				example, to map IOAPIC-ID decimal 10 to
1786				PCI device 00:14.0 write the parameter as:
1787					ivrs_ioapic[10]=00:14.0
1789		ivrs_hpet	[HW,X86_64]
1790				Provide an override to the HPET-ID<->DEVICE-ID
1791				mapping provided in the IVRS ACPI table. For
1792				example, to map HPET-ID decimal 0 to
1793				PCI device 00:14.0 write the parameter as:
1794					ivrs_hpet[0]=00:14.0
1796		ivrs_acpihid	[HW,X86_64]
1797				Provide an override to the ACPI-HID:UID<->DEVICE-ID
1798				mapping provided in the IVRS ACPI table. For
1799				example, to map UART-HID:UID AMD0020:0 to
1800				PCI device 00:14.5 write the parameter as:
1801					ivrs_acpihid[00:14.5]=AMD0020:0
1803		js=		[HW,JOY] Analog joystick
1804				See Documentation/input/joystick.txt.
1806		kaslr/nokaslr	[X86]
1807				Enable/disable kernel and module base offset ASLR
1808				(Address Space Layout Randomization) if built into
1809				the kernel. When CONFIG_HIBERNATION is selected,
1810				kASLR is disabled by default. When kASLR is enabled,
1811				hibernation will be disabled.
1813		keepinitrd	[HW,ARM]
1815		kernelcore=	[KNL,X86,IA-64,PPC]
1816				Format: nn[KMGTPE] | "mirror"
1817				This parameter
1818				specifies the amount of memory usable by the kernel
1819				for non-movable allocations.  The requested amount is
1820				spread evenly throughout all nodes in the system. The
1821				remaining memory in each node is used for Movable
1822				pages. In the event, a node is too small to have both
1823				kernelcore and Movable pages, kernelcore pages will
1824				take priority and other nodes will have a larger number
1825				of Movable pages.  The Movable zone is used for the
1826				allocation of pages that may be reclaimed or moved
1827				by the page migration subsystem.  This means that
1828				HugeTLB pages may not be allocated from this zone.
1829				Note that allocations like PTEs-from-HighMem still
1830				use the HighMem zone if it exists, and the Normal
1831				zone if it does not.
1833				Instead of specifying the amount of memory (nn[KMGTPE]),
1834				you can specify "mirror" option. In case "mirror"
1835				option is specified, mirrored (reliable) memory is used
1836				for non-movable allocations and remaining memory is used
1837				for Movable pages. nn[KMGTPE] and "mirror" are exclusive,
1838				so you can NOT specify nn[KMGTPE] and "mirror" at the same
1839				time.
1841		kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
1842				Format: <Controller#>[,poll interval]
1843				The controller # is the number of the ehci usb debug
1844				port as it is probed via PCI.  The poll interval is
1845				optional and is the number seconds in between
1846				each poll cycle to the debug port in case you need
1847				the functionality for interrupting the kernel with
1848				gdb or control-c on the dbgp connection.  When
1849				not using this parameter you use sysrq-g to break into
1850				the kernel debugger.
1852		kgdboc=		[KGDB,HW] kgdb over consoles.
1853				Requires a tty driver that supports console polling,
1854				or a supported polling keyboard driver (non-usb).
1855				 Serial only format: <serial_device>[,baud]
1856				 keyboard only format: kbd
1857				 keyboard and serial format: kbd,<serial_device>[,baud]
1858				Optional Kernel mode setting:
1859				 kms, kbd format: kms,kbd
1860				 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1862		kgdbwait	[KGDB] Stop kernel execution and enter the
1863				kernel debugger at the earliest opportunity.
1865		kmac=		[MIPS] korina ethernet MAC address.
1866				Configure the RouterBoard 532 series on-chip
1867				Ethernet adapter MAC address.
1869		kmemleak=	[KNL] Boot-time kmemleak enable/disable
1870				Valid arguments: on, off
1871				Default: on
1873				the default is off.
1875		kmemcheck=	[X86] Boot-time kmemcheck enable/disable/one-shot mode
1876				Valid arguments: 0, 1, 2
1877				kmemcheck=0 (disabled)
1878				kmemcheck=1 (enabled)
1879				kmemcheck=2 (one-shot mode)
1880				Default: 2 (one-shot mode)
1882		kstack=N	[X86] Print N words from the kernel stack
1883				in oops dumps.
1885		kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1886				Default is 0 (don't ignore, but inject #GP)
1888		kvm.mmu_audit=	[KVM] This is a R/W parameter which allows audit
1889				KVM MMU at runtime.
1890				Default is 0 (off)
1892		kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.
1893				Default is 1 (enabled)
1895		kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)
1896				for all guests.
1897				Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1899		kvm-intel.ept=	[KVM,Intel] Disable extended page tables
1900				(virtualized MMU) support on capable Intel chips.
1901				Default is 1 (enabled)
1903		kvm-intel.emulate_invalid_guest_state=
1904				[KVM,Intel] Enable emulation of invalid guest states
1905				Default is 0 (disabled)
1907		kvm-intel.flexpriority=
1908				[KVM,Intel] Disable FlexPriority feature (TPR shadow).
1909				Default is 1 (enabled)
1911		kvm-intel.nested=
1912				[KVM,Intel] Enable VMX nesting (nVMX).
1913				Default is 0 (disabled)
1915		kvm-intel.unrestricted_guest=
1916				[KVM,Intel] Disable unrestricted guest feature
1917				(virtualized real and unpaged mode) on capable
1918				Intel chips. Default is 1 (enabled)
1920		kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification
1921				feature (tagged TLBs) on capable Intel chips.
1922				Default is 1 (enabled)
1924		l2cr=		[PPC]
1926		l3cr=		[PPC]
1928		lapic		[X86-32,APIC] Enable the local APIC even if BIOS
1929				disabled it.
1931		lapic=		[x86,APIC] "notscdeadline" Do not use TSC deadline
1932				value for LAPIC timer one-shot implementation. Default
1933				back to the programmable timer unit in the LAPIC.
1935		lapic_timer_c2_ok	[X86,APIC] trust the local apic timer
1936				in C2 power state.
1938		libata.dma=	[LIBATA] DMA control
1939				libata.dma=0	  Disable all PATA and SATA DMA
1940				libata.dma=1	  PATA and SATA Disk DMA only
1941				libata.dma=2	  ATAPI (CDROM) DMA only
1942				libata.dma=4	  Compact Flash DMA only
1943				Combinations also work, so libata.dma=3 enables DMA
1944				for disks and CDROMs, but not CFs.
1946		libata.ignore_hpa=	[LIBATA] Ignore HPA limit
1947				libata.ignore_hpa=0	  keep BIOS limits (default)
1948				libata.ignore_hpa=1	  ignore limits, using full disk
1950		libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
1951				when set.
1952				Format: <int>
1954		libata.force=	[LIBATA] Force configurations.  The format is comma
1955				separated list of "[ID:]VAL" where ID is
1956				PORT[.DEVICE].  PORT and DEVICE are decimal numbers
1957				matching port, link or device.  Basically, it matches
1958				the ATA ID string printed on console by libata.  If
1959				the whole ID part is omitted, the last PORT and DEVICE
1960				values are used.  If ID hasn't been specified yet, the
1961				configuration applies to all ports, links and devices.
1963				If only DEVICE is omitted, the parameter applies to
1964				the port and all links and devices behind it.  DEVICE
1965				number of 0 either selects the first device or the
1966				first fan-out link behind PMP device.  It does not
1967				select the host link.  DEVICE number of 15 selects the
1968				host link and device attached to it.
1970				The VAL specifies the configuration to force.  As long
1971				as there's no ambiguity shortcut notation is allowed.
1972				For example, both 1.5 and 1.5G would work for 1.5Gbps.
1973				The following configurations can be forced.
1975				* Cable type: 40c, 80c, short40c, unk, ign or sata.
1976				  Any ID with matching PORT is used.
1978				* SATA link speed limit: 1.5Gbps or 3.0Gbps.
1980				* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1981				  udma[/][16,25,33,44,66,100,133] notation is also
1982				  allowed.
1984				* [no]ncq: Turn on or off NCQ.
1986				* [no]ncqtrim: Turn off queued DSM TRIM.
1988				* nohrst, nosrst, norst: suppress hard, soft
1989	                          and both resets.
1991				* rstonce: only attempt one reset during
1992				  hot-unplug link recovery
1994				* dump_id: dump IDENTIFY data.
1996				* atapi_dmadir: Enable ATAPI DMADIR bridge support
1998				* disable: Disable this device.
2000				If there are multiple matching configurations changing
2001				the same attribute, the last one is used.
2003		memblock=debug	[KNL] Enable memblock debug messages.
2005		load_ramdisk=	[RAM] List of ramdisks to load from floppy
2006				See Documentation/blockdev/ramdisk.txt.
2008		lockd.nlm_grace_period=P  [NFS] Assign grace period.
2009				Format: <integer>
2011		lockd.nlm_tcpport=N	[NFS] Assign TCP port.
2012				Format: <integer>
2014		lockd.nlm_timeout=T	[NFS] Assign timeout value.
2015				Format: <integer>
2017		lockd.nlm_udpport=M	[NFS] Assign UDP port.
2018				Format: <integer>
2020		locktorture.nreaders_stress= [KNL]
2021				Set the number of locking read-acquisition kthreads.
2022				Defaults to being automatically set based on the
2023				number of online CPUs.
2025		locktorture.nwriters_stress= [KNL]
2026				Set the number of locking write-acquisition kthreads.
2028		locktorture.onoff_holdoff= [KNL]
2029				Set time (s) after boot for CPU-hotplug testing.
2031		locktorture.onoff_interval= [KNL]
2032				Set time (s) between CPU-hotplug operations, or
2033				zero to disable CPU-hotplug testing.
2035		locktorture.shuffle_interval= [KNL]
2036				Set task-shuffle interval (jiffies).  Shuffling
2037				tasks allows some CPUs to go into dyntick-idle
2038				mode during the locktorture test.
2040		locktorture.shutdown_secs= [KNL]
2041				Set time (s) after boot system shutdown.  This
2042				is useful for hands-off automated testing.
2044		locktorture.stat_interval= [KNL]
2045				Time (s) between statistics printk()s.
2047		locktorture.stutter= [KNL]
2048				Time (s) to stutter testing, for example,
2049				specifying five seconds causes the test to run for
2050				five seconds, wait for five seconds, and so on.
2051				This tests the locking primitive's ability to
2052				transition abruptly to and from idle.
2054		locktorture.torture_runnable= [BOOT]
2055				Start locktorture running at boot time.
2057		locktorture.torture_type= [KNL]
2058				Specify the locking implementation to test.
2060		locktorture.verbose= [KNL]
2061				Enable additional printk() statements.
2063		logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
2064				Format: <irq>
2066		loglevel=	All Kernel Messages with a loglevel smaller than the
2067				console loglevel will be printed to the console. It can
2068				also be changed with klogd or other programs. The
2069				loglevels are defined as follows:
2071				0 (KERN_EMERG)		system is unusable
2072				1 (KERN_ALERT)		action must be taken immediately
2073				2 (KERN_CRIT)		critical conditions
2074				3 (KERN_ERR)		error conditions
2075				4 (KERN_WARNING)	warning conditions
2076				5 (KERN_NOTICE)		normal but significant condition
2077				6 (KERN_INFO)		informational
2078				7 (KERN_DEBUG)		debug-level messages
2080		log_buf_len=n[KMG]	Sets the size of the printk ring buffer,
2081				in bytes.  n must be a power of two and greater
2082				than the minimal size. The minimal size is defined
2083				by LOG_BUF_SHIFT kernel config parameter. There is
2084				also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
2085				that allows to increase the default size depending on
2086				the number of CPUs. See init/Kconfig for more details.
2088		logo.nologo	[FB] Disables display of the built-in Linux logo.
2089				This may be used to provide more screen space for
2090				kernel log messages and is useful when debugging
2091				kernel boot problems.
2093		lp=0		[LP]	Specify parallel ports to use, e.g,
2094		lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
2095		lp=reset		first parallel port). 'lp=0' disables the
2096		lp=auto			printer driver. 'lp=reset' (which can be
2097					specified in addition to the ports) causes
2098					attached printers to be reset. Using
2099					lp=port1,port2,... specifies the parallel ports
2100					to associate lp devices with, starting with
2101					lp0. A port specification may be 'none' to skip
2102					that lp device, or a parport name such as
2103					'parport0'. Specifying 'lp=auto' instead of a
2104					port specification list means that device IDs
2105					from each port should be examined, to see if
2106					an IEEE 1284-compliant printer is attached; if
2107					so, the driver will manage that printer.
2108					See also header of drivers/char/lp.c.
2110		lpj=n		[KNL]
2111				Sets loops_per_jiffy to given constant, thus avoiding
2112				time-consuming boot-time autodetection (up to 250 ms per
2113				CPU). 0 enables autodetection (default). To determine
2114				the correct value for your kernel, boot with normal
2115				autodetection and see what value is printed. Note that
2116				on SMP systems the preset will be applied to all CPUs,
2117				which is likely to cause problems if your CPUs need
2118				significantly divergent settings. An incorrect value
2119				will cause delays in the kernel to be wrong, leading to
2120				unpredictable I/O errors and other breakage. Although
2121				unlikely, in the extreme case this might damage your
2122				hardware.
2124		ltpc=		[NET]
2125				Format: <io>,<irq>,<dma>
2127		machvec=	[IA-64] Force the use of a particular machine-vector
2128				(machvec) in a generic kernel.
2129				Example: machvec=hpzx1_swiotlb
2131		machtype=	[Loongson] Share the same kernel image file between different
2132				 yeeloong laptop.
2133				Example: machtype=lemote-yeeloong-2f-7inch
2135		max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater
2136				than or equal to this physical address is ignored.
2138		maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
2139				should make use of.  maxcpus=n : n >= 0 limits the
2140				kernel to using 'n' processors.  n=0 is a special case,
2141				it is equivalent to "nosmp", which also disables
2142				the IO APIC.
2144		max_loop=	[LOOP] The number of loop block devices that get
2145		(loop.max_loop)	unconditionally pre-created at init time. The default
2146				number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
2147				of statically allocating a predefined number, loop
2148				devices can be requested on-demand with the
2149				/dev/loop-control interface.
2151		mce		[X86-32] Machine Check Exception
2153		mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.txt
2155		md=		[HW] RAID subsystems devices and level
2156				See Documentation/md.txt.
2158		mdacon=		[MDA]
2159				Format: <first>,<last>
2160				Specifies range of consoles to be captured by the MDA.
2162		mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
2163				Amount of memory to be used when the kernel is not able
2164				to see the whole system memory or for test.
2165				[X86] Work as limiting max address. Use together
2166				with memmap= to avoid physical address space collisions.
2167				Without memmap= PCI devices could be placed at addresses
2168				belonging to unused RAM.
2170		mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
2171				memory.
2173		memchunk=nn[KMG]
2174				[KNL,SH] Allow user to override the default size for
2175				per-device physically contiguous DMA buffers.
2177	        memhp_default_state=online/offline
2178				[KNL] Set the initial state for the memory hotplug
2179				onlining policy. If not specified, the default value is
2180				set according to the
2182				option.
2183				See Documentation/memory-hotplug.txt.
2185		memmap=exactmap	[KNL,X86] Enable setting of an exact
2186				E820 memory map, as specified by the user.
2187				Such memmap=exactmap lines can be constructed based on
2188				BIOS output or other requirements. See the memmap=nn@ss
2189				option description.
2191		memmap=nn[KMG]@ss[KMG]
2192				[KNL] Force usage of a specific region of memory.
2193				Region of memory to be used is from ss to ss+nn.
2195		memmap=nn[KMG]#ss[KMG]
2196				[KNL,ACPI] Mark specific memory as ACPI data.
2197				Region of memory to be marked is from ss to ss+nn.
2199		memmap=nn[KMG]$ss[KMG]
2200				[KNL,ACPI] Mark specific memory as reserved.
2201				Region of memory to be reserved is from ss to ss+nn.
2202				Example: Exclude memory from 0x18690000-0x1869ffff
2203				         memmap=64K$0x18690000
2204				         or
2205				         memmap=0x10000$0x18690000
2207		memmap=nn[KMG]!ss[KMG]
2208				[KNL,X86] Mark specific memory as protected.
2209				Region of memory to be used, from ss to ss+nn.
2210				The memory region may be marked as e820 type 12 (0xc)
2211				and is NVDIMM or ADR memory.
2213		memory_corruption_check=0/1 [X86]
2214				Some BIOSes seem to corrupt the first 64k of
2215				memory when doing things like suspend/resume.
2216				Setting this option will scan the memory
2217				looking for corruption.  Enabling this will
2218				both detect corruption and prevent the kernel
2219				from using the memory being corrupted.
2220				However, its intended as a diagnostic tool; if
2221				repeatable BIOS-originated corruption always
2222				affects the same memory, you can use memmap=
2223				to prevent the kernel from using that memory.
2225		memory_corruption_check_size=size [X86]
2226				By default it checks for corruption in the low
2227				64k, making this memory unavailable for normal
2228				use.  Use this parameter to scan for
2229				corruption in more or less memory.
2231		memory_corruption_check_period=seconds [X86]
2232				By default it checks for corruption every 60
2233				seconds.  Use this parameter to check at some
2234				other rate.  0 disables periodic checking.
2236		memtest=	[KNL,X86,ARM] Enable memtest
2237				Format: <integer>
2238				default : 0 <disable>
2239				Specifies the number of memtest passes to be
2240				performed. Each pass selects another test
2241				pattern from a given set of patterns. Memtest
2242				fills the memory with this pattern, validates
2243				memory contents and reserves bad memory
2244				regions that are detected.
2246		meye.*=		[HW] Set MotionEye Camera parameters
2247				See Documentation/video4linux/meye.txt.
2249		mfgpt_irq=	[IA-32] Specify the IRQ to use for the
2250				Multi-Function General Purpose Timers on AMD Geode
2251				platforms.
2253		mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
2254				the BIOS has incorrectly applied a workaround. TinyBIOS
2255				version 0.98 is known to be affected, 0.99 fixes the
2256				problem by letting the user disable the workaround.
2258		mga=		[HW,DRM]
2260		min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this
2261				physical address is ignored.
2263		mini2440=	[ARM,HW,KNL]
2264				Format:[0..2][b][c][t]
2265				Default: "0tb"
2266				MINI2440 configuration specification:
2267				0 - The attached screen is the 3.5" TFT
2268				1 - The attached screen is the 7" TFT
2269				2 - The VGA Shield is attached (1024x768)
2270				Leaving out the screen size parameter will not load
2271				the TFT driver, and the framebuffer will be left
2272				unconfigured.
2273				b - Enable backlight. The TFT backlight pin will be
2274				linked to the kernel VESA blanking code and a GPIO
2275				LED. This parameter is not necessary when using the
2276				VGA shield.
2277				c - Enable the s3c camera interface.
2278				t - Reserved for enabling touchscreen support. The
2279				touchscreen support is not enabled in the mainstream
2280				kernel as of 2.6.30, a preliminary port can be found
2281				in the "bleeding edge" mini2440 support kernel at
2282				http://repo.or.cz/w/linux-2.6/mini2440.git
2284		mminit_loglevel=
2285				[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
2286				parameter allows control of the logging verbosity for
2287				the additional memory initialisation checks. A value
2288				of 0 disables mminit logging and a level of 4 will
2289				log everything. Information is printed at KERN_DEBUG
2290				so loglevel=8 may also need to be specified.
2292		module.sig_enforce
2293				[KNL] When CONFIG_MODULE_SIG is set, this means that
2294				modules without (valid) signatures will fail to load.
2295				Note that if CONFIG_MODULE_SIG_FORCE is set, that
2296				is always true, so this option does nothing.
2298		mousedev.tap_time=
2299				[MOUSE] Maximum time between finger touching and
2300				leaving touchpad surface for touch to be considered
2301				a tap and be reported as a left button click (for
2302				touchpads working in absolute mode only).
2303				Format: <msecs>
2304		mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
2305				reporting absolute coordinates, such as tablets
2306		mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
2307				reporting absolute coordinates, such as tablets
2309		movablecore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
2310				is similar to kernelcore except it specifies the
2311				amount of memory used for migratable allocations.
2312				If both kernelcore and movablecore is specified,
2313				then kernelcore will be at *least* the specified
2314				value but may be more. If movablecore on its own
2315				is specified, the administrator must be careful
2316				that the amount of memory usable for all allocations
2317				is not too small.
2319		movable_node	[KNL,X86] Boot-time switch to enable the effects
2320				of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
2322		MTD_Partition=	[MTD]
2323				Format: <name>,<region-number>,<size>,<offset>
2325		MTD_Region=	[MTD] Format:
2326				<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
2328		mtdparts=	[MTD]
2329				See drivers/mtd/cmdlinepart.c.
2331		multitce=off	[PPC]  This parameter disables the use of the pSeries
2332				firmware feature for updating multiple TCE entries
2333				at a time.
2335		onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
2337				Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
2339				boundary - index of last SLC block on Flex-OneNAND.
2340					   The remaining blocks are configured as MLC blocks.
2341				lock	 - Configure if Flex-OneNAND boundary should be locked.
2342					   Once locked, the boundary cannot be changed.
2343					   1 indicates lock status, 0 indicates unlock status.
2345		mtdset=		[ARM]
2346				ARM/S3C2412 JIVE boot control
2348				See arch/arm/mach-s3c2412/mach-jive.c
2350		mtouchusb.raw_coordinates=
2351				[HW] Make the MicroTouch USB driver use raw coordinates
2352				('y', default) or cooked coordinates ('n')
2354		mtrr_chunk_size=nn[KMG] [X86]
2355				used for mtrr cleanup. It is largest continuous chunk
2356				that could hold holes aka. UC entries.
2358		mtrr_gran_size=nn[KMG] [X86]
2359				Used for mtrr cleanup. It is granularity of mtrr block.
2360				Default is 1.
2361				Large value could prevent small alignment from
2362				using up MTRRs.
2364		mtrr_spare_reg_nr=n [X86]
2365				Format: <integer>
2366				Range: 0,7 : spare reg number
2367				Default : 1
2368				Used for mtrr cleanup. It is spare mtrr entries number.
2369				Set to 2 or more if your graphical card needs more.
2371		n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card
2373		netdev=		[NET] Network devices parameters
2374				Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
2375				Note that mem_start is often overloaded to mean
2376				something different and driver-specific.
2377				This usage is only documented in each driver source
2378				file if at all.
2380		nf_conntrack.acct=
2381				[NETFILTER] Enable connection tracking flow accounting
2382				0 to disable accounting
2383				1 to enable accounting
2384				Default value is 0.
2386		nfsaddrs=	[NFS] Deprecated.  Use ip= instead.
2387				See Documentation/filesystems/nfs/nfsroot.txt.
2389		nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
2390				See Documentation/filesystems/nfs/nfsroot.txt.
2392		nfsrootdebug	[NFS] enable nfsroot debugging messages.
2393				See Documentation/filesystems/nfs/nfsroot.txt.
2395		nfs.callback_tcpport=
2396				[NFS] set the TCP port on which the NFSv4 callback
2397				channel should listen.
2399		nfs.cache_getent=
2400				[NFS] sets the pathname to the program which is used
2401				to update the NFS client cache entries.
2403		nfs.cache_getent_timeout=
2404				[NFS] sets the timeout after which an attempt to
2405				update a cache entry is deemed to have failed.
2407		nfs.idmap_cache_timeout=
2408				[NFS] set the maximum lifetime for idmapper cache
2409				entries.
2411		nfs.enable_ino64=
2412				[NFS] enable 64-bit inode numbers.
2413				If zero, the NFS client will fake up a 32-bit inode
2414				number for the readdir() and stat() syscalls instead
2415				of returning the full 64-bit number.
2416				The default is to return 64-bit inode numbers.
2418		nfs.max_session_slots=
2419				[NFSv4.1] Sets the maximum number of session slots
2420				the client will attempt to negotiate with the server.
2421				This limits the number of simultaneous RPC requests
2422				that the client can send to the NFSv4.1 server.
2423				Note that there is little point in setting this
2424				value higher than the max_tcp_slot_table_limit.
2426		nfs.nfs4_disable_idmapping=
2427				[NFSv4] When set to the default of '1', this option
2428				ensures that both the RPC level authentication
2429				scheme and the NFS level operations agree to use
2430				numeric uids/gids if the mount is using the
2431				'sec=sys' security flavour. In effect it is
2432				disabling idmapping, which can make migration from
2433				legacy NFSv2/v3 systems to NFSv4 easier.
2434				Servers that do not support this mode of operation
2435				will be autodetected by the client, and it will fall
2436				back to using the idmapper.
2437				To turn off this behaviour, set the value to '0'.
2438		nfs.nfs4_unique_id=
2439				[NFS4] Specify an additional fixed unique ident-
2440				ification string that NFSv4 clients can insert into
2441				their nfs_client_id4 string.  This is typically a
2442				UUID that is generated at system install time.
2444		nfs.send_implementation_id =
2445				[NFSv4.1] Send client implementation identification
2446				information in exchange_id requests.
2447				If zero, no implementation identification information
2448				will be sent.
2449				The default is to send the implementation identification
2450				information.
2452		nfs.recover_lost_locks =
2453				[NFSv4] Attempt to recover locks that were lost due
2454				to a lease timeout on the server. Please note that
2455				doing this risks data corruption, since there are
2456				no guarantees that the file will remain unchanged
2457				after the locks are lost.
2458				If you want to enable the kernel legacy behaviour of
2459				attempting to recover these locks, then set this
2460				parameter to '1'.
2461				The default parameter value of '0' causes the kernel
2462				not to attempt recovery of lost locks.
2464		nfs4.layoutstats_timer =
2465				[NFSv4.2] Change the rate at which the kernel sends
2466				layoutstats to the pNFS metadata server.
2468				Setting this to value to 0 causes the kernel to use
2469				whatever value is the default set by the layout
2470				driver. A non-zero value sets the minimum interval
2471				in seconds between layoutstats transmissions.
2473		nfsd.nfs4_disable_idmapping=
2474				[NFSv4] When set to the default of '1', the NFSv4
2475				server will return only numeric uids and gids to
2476				clients using auth_sys, and will accept numeric uids
2477				and gids from such clients.  This is intended to ease
2478				migration from NFSv2/v3.
2480		objlayoutdriver.osd_login_prog=
2481				[NFS] [OBJLAYOUT] sets the pathname to the program which
2482				is used to automatically discover and login into new
2483				osd-targets. Please see:
2484				Documentation/filesystems/pnfs.txt for more explanations
2486		nmi_debug=	[KNL,AVR32,SH] Specify one or more actions to take
2487				when a NMI is triggered.
2488				Format: [state][,regs][,debounce][,die]
2490		nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels
2491				Format: [panic,][nopanic,][num]
2492				Valid num: 0 or 1
2493				0 - turn hardlockup detector in nmi_watchdog off
2494				1 - turn hardlockup detector in nmi_watchdog on
2495				When panic is specified, panic when an NMI watchdog
2496				timeout occurs (or 'nopanic' to override the opposite
2497				default). To disable both hard and soft lockup detectors,
2498				please see 'nowatchdog'.
2499				This is useful when you use a panic=... timeout and
2500				need the box quickly up again.
2502		netpoll.carrier_timeout=
2503				[NET] Specifies amount of time (in seconds) that
2504				netpoll should wait for a carrier. By default netpoll
2505				waits 4 seconds.
2507		no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
2508				emulation library even if a 387 maths coprocessor
2509				is present.
2511		no_console_suspend
2512				[HW] Never suspend the console
2513				Disable suspending of consoles during suspend and
2514				hibernate operations.  Once disabled, debugging
2515				messages can reach various consoles while the rest
2516				of the system is being put to sleep (ie, while
2517				debugging driver suspend/resume hooks).  This may
2518				not work reliably with all consoles, but is known
2519				to work with serial and VGA consoles.
2520				To facilitate more flexible debugging, we also add
2521				console_suspend, a printk module parameter to control
2522				it. Users could use console_suspend (usually
2523				/sys/module/printk/parameters/console_suspend) to
2524				turn on/off it dynamically.
2526		noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
2527				caches in the slab allocator.  Saves per-node memory,
2528				but will impact performance.
2530		noalign		[KNL,ARM]
2532		noapic		[SMP,APIC] Tells the kernel to not make use of any
2533				IOAPICs that may be present in the system.
2535		noautogroup	Disable scheduler automatic task group creation.
2537		nobats		[PPC] Do not use BATs for mapping kernel lowmem
2538				on "Classic" PPC cores.
2540		nocache		[ARM]
2542		noclflush	[BUGS=X86] Don't use the CLFLUSH instruction
2544		nodelayacct	[KNL] Disable per-task delay accounting
2546		nodisconnect	[HW,SCSI,M68K] Disables SCSI disconnects.
2548		nodsp		[SH] Disable hardware DSP at boot time.
2550		noefi		Disable EFI runtime services support.
2552		noexec		[IA-64]
2554		noexec		[X86]
2555				On X86-32 available only on PAE configured kernels.
2556				noexec=on: enable non-executable mappings (default)
2557				noexec=off: disable non-executable mappings
2559		nosmap		[X86]
2560				Disable SMAP (Supervisor Mode Access Prevention)
2561				even if it is supported by processor.
2563		nosmep		[X86]
2564				Disable SMEP (Supervisor Mode Execution Prevention)
2565				even if it is supported by processor.
2567		noexec32	[X86-64]
2568				This affects only 32-bit executables.
2569				noexec32=on: enable non-executable mappings (default)
2570					read doesn't imply executable mappings
2571				noexec32=off: disable non-executable mappings
2572					read implies executable mappings
2574		nofpu		[MIPS,SH] Disable hardware FPU at boot time.
2576		nofxsr		[BUGS=X86-32] Disables x86 floating point extended
2577				register save and restore. The kernel will only save
2578				legacy floating-point registers on task switch.
2580		nohugeiomap	[KNL,x86] Disable kernel huge I/O mappings.
2582		nosmt		[KNL,S390] Disable symmetric multithreading (SMT).
2583				Equivalent to smt=1.
2585		noxsave		[BUGS=X86] Disables x86 extended register state save
2586				and restore using xsave. The kernel will fallback to
2587				enabling legacy floating-point and sse state.
2589		noxsaveopt	[X86] Disables xsaveopt used in saving x86 extended
2590				register states. The kernel will fall back to use
2591				xsave to save the states. By using this parameter,
2592				performance of saving the states is degraded because
2593				xsave doesn't support modified optimization while
2594				xsaveopt supports it on xsaveopt enabled systems.
2596		noxsaves	[X86] Disables xsaves and xrstors used in saving and
2597				restoring x86 extended register state in compacted
2598				form of xsave area. The kernel will fall back to use
2599				xsaveopt and xrstor to save and restore the states
2600				in standard form of xsave area. By using this
2601				parameter, xsave area per process might occupy more
2602				memory on xsaves enabled systems.
2604		nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
2605				wfi(ARM) instruction doesn't work correctly and not to
2606				use it. This is also useful when using JTAG debugger.
2608		no_file_caps	Tells the kernel not to honor file capabilities.  The
2609				only way then for a file to be executed with privilege
2610				is to be setuid root or executed by root.
2612		nohalt		[IA-64] Tells the kernel not to use the power saving
2613				function PAL_HALT_LIGHT when idle. This increases
2614				power-consumption. On the positive side, it reduces
2615				interrupt wake-up latency, which may improve performance
2616				in certain environments such as networked servers or
2617				real-time systems.
2619		nohibernate	[HIBERNATION] Disable hibernation and resume.
2621		nohz=		[KNL] Boottime enable/disable dynamic ticks
2622				Valid arguments: on, off
2623				Default: on
2625		nohz_full=	[KNL,BOOT]
2626				In kernels built with CONFIG_NO_HZ_FULL=y, set
2627				the specified list of CPUs whose tick will be stopped
2628				whenever possible. The boot CPU will be forced outside
2629				the range to maintain the timekeeping.
2630				The CPUs in this range must also be included in the
2631				rcu_nocbs= set.
2633		noiotrap	[SH] Disables trapped I/O port accesses.
2635		noirqdebug	[X86-32] Disables the code which attempts to detect and
2636				disable unhandled interrupt sources.
2638		no_timer_check	[X86,APIC] Disables the code which tests for
2639				broken timer IRQ sources.
2641		noisapnp	[ISAPNP] Disables ISA PnP code.
2643		noinitrd	[RAM] Tells the kernel not to load any configured
2644				initial RAM disk.
2646		nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt
2647				remapping.
2648				[Deprecated - use intremap=off]
2650		nointroute	[IA-64]
2652		noinvpcid	[X86] Disable the INVPCID cpu feature.
2654		nojitter	[IA-64] Disables jitter checking for ITC timers.
2656		no-kvmclock	[X86,KVM] Disable paravirtualized KVM clock driver
2658		no-kvmapf	[X86,KVM] Disable paravirtualized asynchronous page
2659				fault handling.
2661		no-steal-acc    [X86,KVM] Disable paravirtualized steal time accounting.
2662				steal time is computed, but won't influence scheduler
2663				behaviour
2665		nolapic		[X86-32,APIC] Do not enable or use the local APIC.
2667		nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
2669		noltlbs		[PPC] Do not use large page/tlb entries for kernel
2670				lowmem mapping on PPC40x and PPC8xx
2672		nomca		[IA-64] Disable machine check abort handling
2674		nomce		[X86-32] Disable Machine Check Exception
2676		nomfgpt		[X86-32] Disable Multi-Function General Purpose
2677				Timer usage (for AMD Geode machines).
2679		nonmi_ipi	[X86] Disable using NMI IPIs during panic/reboot to
2680				shutdown the other cpus.  Instead use the REBOOT_VECTOR
2681				irq.
2683		nomodule	Disable module load
2685		nopat		[X86] Disable PAT (page attribute table extension of
2686				pagetables) support.
2688		norandmaps	Don't use address space randomization.  Equivalent to
2689				echo 0 > /proc/sys/kernel/randomize_va_space
2691		noreplace-paravirt	[X86,IA-64,PV_OPS] Don't patch paravirt_ops
2693		noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
2694				with UP alternatives
2696		nordrand	[X86] Disable kernel use of the RDRAND and
2697				RDSEED instructions even if they are supported
2698				by the processor.  RDRAND and RDSEED are still
2699				available to user space applications.
2701		noresume	[SWSUSP] Disables resume and restores original swap
2702				space.
2704		no-scroll	[VGA] Disables scrollback.
2705				This is required for the Braillex ib80-piezo Braille
2706				reader made by F.H. Papenmeier (Germany).
2708		nosbagart	[IA-64]
2710		nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
2712		nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
2713				and disable the IO APIC.  legacy for "maxcpus=0".
2715		nosoftlockup	[KNL] Disable the soft-lockup detector.
2717		nosync		[HW,M68K] Disables sync negotiation for all devices.
2719		notsc		[BUGS=X86-32] Disable Time Stamp Counter
2721		nowatchdog	[KNL] Disable both lockup detectors, i.e.
2722	                        soft-lockup and NMI watchdog (hard-lockup).
2724		nowb		[ARM]
2726		nox2apic	[X86-64,APIC] Do not enable x2APIC mode.
2728		cpu0_hotplug	[X86] Turn on CPU0 hotplug feature when
2730				Some features depend on CPU0. Known dependencies are:
2731				1. Resume from suspend/hibernate depends on CPU0.
2732				Suspend/hibernate will fail if CPU0 is offline and you
2733				need to online CPU0 before suspend/hibernate.
2734				2. PIC interrupts also depend on CPU0. CPU0 can't be
2735				removed if a PIC interrupt is detected.
2736				It's said poweroff/reboot may depend on CPU0 on some
2737				machines although I haven't seen such issues so far
2738				after CPU0 is offline on a few tested machines.
2739				If the dependencies are under your control, you can
2740				turn on cpu0_hotplug.
2742		nptcg=		[IA-64] Override max number of concurrent global TLB
2743				purges which is reported from either PAL_VM_SUMMARY or
2744				SAL PALO.
2746		nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
2747				could support.  nr_cpus=n : n >= 1 limits the kernel to
2748				supporting 'n' processors. Later in runtime you can not
2749				use hotplug cpu feature to put more cpu back to online.
2750				just like you compile the kernel NR_CPUS=n
2752		nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
2754		numa_balancing=	[KNL,X86] Enable or disable automatic NUMA balancing.
2755				Allowed values are enable and disable
2757		numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2758				one of ['zone', 'node', 'default'] can be specified
2759				This can be set from sysctl after boot.
2760				See Documentation/sysctl/vm.txt for details.
2762		ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
2763				See Documentation/debugging-via-ohci1394.txt for more
2764				info.
2766		olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2767				Rather than timing out after 20 ms if an EC
2768				command is not properly ACKed, override the length
2769				of the timeout.  We have interrupts disabled while
2770				waiting for the ACK, so if this is set too high
2771				interrupts *may* be lost!
2773		omap_mux=	[OMAP] Override bootloader pin multiplexing.
2774				Format: <mux_mode0.mode_name=value>...
2775				For example, to override I2C bus2:
2776				omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2778		oprofile.timer=	[HW]
2779				Use timer interrupt instead of performance counters
2781		oprofile.cpu_type=	Force an oprofile cpu type
2782				This might be useful if you have an older oprofile
2783				userland or if you want common events.
2784				Format: { arch_perfmon }
2785				arch_perfmon: [X86] Force use of architectural
2786					perfmon on Intel CPUs instead of the
2787					CPU specific event set.
2788				timer: [X86] Force use of architectural NMI
2789					timer mode (see also oprofile.timer
2790					for generic hr timer mode)
2791					[s390] Force legacy basic mode sampling
2792	                                (report cpu_type "timer")
2794		oops=panic	Always panic on oopses. Default is to just kill the
2795				process, but there is a small probability of
2796				deadlocking the machine.
2797				This will also cause panics on machine check exceptions.
2798				Useful together with panic=30 to trigger a reboot.
2800		OSS		[HW,OSS]
2801				See Documentation/sound/oss/oss-parameters.txt
2803		page_owner=	[KNL] Boot-time page_owner enabling option.
2804				Storage of the information about who allocated
2805				each page is disabled in default. With this switch,
2806				we can turn it on.
2807				on: enable the feature
2809		page_poison=	[KNL] Boot-time parameter changing the state of
2810				poisoning on the buddy allocator.
2811				off: turn off poisoning
2812				on: turn on poisoning
2814		panic=		[KNL] Kernel behaviour on panic: delay <timeout>
2815				timeout > 0: seconds before rebooting
2816				timeout = 0: wait forever
2817				timeout < 0: reboot immediately
2818				Format: <timeout>
2820		panic_on_warn	panic() instead of WARN().  Useful to cause kdump
2821				on a WARN().
2823		crash_kexec_post_notifiers
2824				Run kdump after running panic-notifiers and dumping
2825				kmsg. This only for the users who doubt kdump always
2826				succeeds in any situation.
2827				Note that this also increases risks of kdump failure,
2828				because some panic notifiers can make the crashed
2829				kernel more unstable.
2831		parkbd.port=	[HW] Parallel port number the keyboard adapter is
2832				connected to, default is 0.
2833				Format: <parport#>
2834		parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
2835				0 for XT, 1 for AT (default is AT).
2836				Format: <mode>
2838		parport=	[HW,PPT] Specify parallel ports. 0 disables.
2839				Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2840				Use 'auto' to force the driver to use any
2841				IRQ/DMA settings detected (the default is to
2842				ignore detected IRQ/DMA settings because of
2843				possible conflicts). You can specify the base
2844				address, IRQ, and DMA settings; IRQ and DMA
2845				should be numbers, or 'auto' (for using detected
2846				settings on that particular port), or 'nofifo'
2847				(to avoid using a FIFO even if it is detected).
2848				Parallel ports are assigned in the order they
2849				are specified on the command line, starting
2850				with parport0.
2852		parport_init_mode=	[HW,PPT]
2853				Configure VIA parallel port to operate in
2854				a specific mode. This is necessary on Pegasos
2855				computer where firmware has no options for setting
2856				up parallel port mode and sets it to spp.
2857				Currently this function knows 686a and 8231 chips.
2858				Format: [spp|ps2|epp|ecp|ecpepp]
2860		pause_on_oops=
2861				Halt all CPUs after the first oops has been printed for
2862				the specified number of seconds.  This is to be used if
2863				your oopses keep scrolling off the screen.
2865		pcbit=		[HW,ISDN]
2867		pcd.		[PARIDE]
2868				See header of drivers/block/paride/pcd.c.
2869				See also Documentation/blockdev/paride.txt.
2871		pci=option[,option...]	[PCI] various PCI subsystem options:
2872			earlydump	[X86] dump PCI config space before the kernel
2873				        changes anything
2874			off		[X86] don't probe for the PCI bus
2875			bios		[X86-32] force use of PCI BIOS, don't access
2876					the hardware directly. Use this if your machine
2877					has a non-standard PCI host bridge.
2878			nobios		[X86-32] disallow use of PCI BIOS, only direct
2879					hardware access methods are allowed. Use this
2880					if you experience crashes upon bootup and you
2881					suspect they are caused by the BIOS.
2882			conf1		[X86] Force use of PCI Configuration Access
2883					Mechanism 1 (config address in IO port 0xCF8,
2884					data in IO port 0xCFC, both 32-bit).
2885			conf2		[X86] Force use of PCI Configuration Access
2886					Mechanism 2 (IO port 0xCF8 is an 8-bit port for
2887					the function, IO port 0xCFA, also 8-bit, sets
2888					bus number. The config space is then accessed
2889					through ports 0xC000-0xCFFF).
2890					See http://wiki.osdev.org/PCI for more info
2891					on the configuration access mechanisms.
2892			noaer		[PCIE] If the PCIEAER kernel config parameter is
2893					enabled, this kernel boot option can be used to
2894					disable the use of PCIE advanced error reporting.
2895			nodomains	[PCI] Disable support for multiple PCI
2896					root domains (aka PCI segments, in ACPI-speak).
2897			nommconf	[X86] Disable use of MMCONFIG for PCI
2898					Configuration
2899			check_enable_amd_mmconf [X86] check for and enable
2900					properly configured MMIO access to PCI
2901					config space on AMD family 10h CPU
2902			nomsi		[MSI] If the PCI_MSI kernel config parameter is
2903					enabled, this kernel boot option can be used to
2904					disable the use of MSI interrupts system-wide.
2905			noioapicquirk	[APIC] Disable all boot interrupt quirks.
2906					Safety option to keep boot IRQs enabled. This
2907					should never be necessary.
2908			ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
2909					primary IO-APIC for bridges that cannot disable
2910					boot IRQs. This fixes a source of spurious IRQs
2911					when the system masks IRQs.
2912			noioapicreroute	[APIC] Disable workaround that uses the
2913					boot IRQ equivalent of an IRQ that connects to
2914					a chipset where boot IRQs cannot be disabled.
2915					The opposite of ioapicreroute.
2916			biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
2917					routing table. These calls are known to be buggy
2918					on several machines and they hang the machine
2919					when used, but on other computers it's the only
2920					way to get the interrupt routing table. Try
2921					this option if the kernel is unable to allocate
2922					IRQs or discover secondary PCI buses on your
2923					motherboard.
2924			rom		[X86] Assign address space to expansion ROMs.
2925					Use with caution as certain devices share
2926					address decoders between ROMs and other
2927					resources.
2928			norom		[X86] Do not assign address space to
2929					expansion ROMs that do not already have
2930					BIOS assigned address ranges.
2931			nobar		[X86] Do not assign address space to the
2932					BARs that weren't assigned by the BIOS.
2933			irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
2934					assigned automatically to PCI devices. You can
2935					make the kernel exclude IRQs of your ISA cards
2936					this way.
2937			pirqaddr=0xAAAAA	[X86] Specify the physical address
2938					of the PIRQ table (normally generated
2939					by the BIOS) if it is outside the
2940					F0000h-100000h range.
2941			lastbus=N	[X86] Scan all buses thru bus #N. Can be
2942					useful if the kernel is unable to find your
2943					secondary buses and you want to tell it
2944					explicitly which ones they are.
2945			assign-busses	[X86] Always assign all PCI bus
2946					numbers ourselves, overriding
2947					whatever the firmware may have done.
2948			usepirqmask	[X86] Honor the possible IRQ mask stored
2949					in the BIOS $PIR table. This is needed on
2950					some systems with broken BIOSes, notably
2951					some HP Pavilion N5400 and Omnibook XE3
2952					notebooks. This will have no effect if ACPI
2953					IRQ routing is enabled.
2954			noacpi		[X86] Do not use ACPI for IRQ routing
2955					or for PCI scanning.
2956			use_crs		[X86] Use PCI host bridge window information
2957					from ACPI.  On BIOSes from 2008 or later, this
2958					is enabled by default.  If you need to use this,
2959					please report a bug.
2960			nocrs		[X86] Ignore PCI host bridge windows from ACPI.
2961				        If you need to use this, please report a bug.
2962			routeirq	Do IRQ routing for all PCI devices.
2963					This is normally done in pci_enable_device(),
2964					so this option is a temporary workaround
2965					for broken drivers that don't call it.
2966			skip_isa_align	[X86] do not align io start addr, so can
2967					handle more pci cards
2968			noearly		[X86] Don't do any early type 1 scanning.
2969					This might help on some broken boards which
2970					machine check when some devices' config space
2971					is read. But various workarounds are disabled
2972					and some IOMMU drivers will not work.
2973			bfsort		Sort PCI devices into breadth-first order.
2974					This sorting is done to get a device
2975					order compatible with older (<= 2.4) kernels.
2976			nobfsort	Don't sort PCI devices into breadth-first order.
2977			pcie_bus_tune_off	Disable PCIe MPS (Max Payload Size)
2978					tuning and use the BIOS-configured MPS defaults.
2979			pcie_bus_safe	Set every device's MPS to the largest value
2980					supported by all devices below the root complex.
2981			pcie_bus_perf	Set device MPS to the largest allowable MPS
2982					based on its parent bus. Also set MRRS (Max
2983					Read Request Size) to the largest supported
2984					value (no larger than the MPS that the device
2985					or bus can support) for best performance.
2986			pcie_bus_peer2peer	Set every device's MPS to 128B, which
2987					every device is guaranteed to support. This
2988					configuration allows peer-to-peer DMA between
2989					any pair of devices, possibly at the cost of
2990					reduced performance.  This also guarantees
2991					that hot-added devices will work.
2992			cbiosize=nn[KMG]	The fixed amount of bus space which is
2993					reserved for the CardBus bridge's IO window.
2994					The default value is 256 bytes.
2995			cbmemsize=nn[KMG]	The fixed amount of bus space which is
2996					reserved for the CardBus bridge's memory
2997					window. The default value is 64 megabytes.
2998			resource_alignment=
2999					Format:
3000					[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
3001					Specifies alignment and device to reassign
3002					aligned memory resources.
3003					If <order of align> is not specified,
3004					PAGE_SIZE is used as alignment.
3005					PCI-PCI bridge can be specified, if resource
3006					windows need to be expanded.
3007			ecrc=		Enable/disable PCIe ECRC (transaction layer
3008					end-to-end CRC checking).
3009					bios: Use BIOS/firmware settings. This is the
3010					the default.
3011					off: Turn ECRC off
3012					on: Turn ECRC on.
3013			hpiosize=nn[KMG]	The fixed amount of bus space which is
3014					reserved for hotplug bridge's IO window.
3015					Default size is 256 bytes.
3016			hpmemsize=nn[KMG]	The fixed amount of bus space which is
3017					reserved for hotplug bridge's memory window.
3018					Default size is 2 megabytes.
3019			realloc=	Enable/disable reallocating PCI bridge resources
3020					if allocations done by BIOS are too small to
3021					accommodate resources required by all child
3022					devices.
3023					off: Turn realloc off
3024					on: Turn realloc on
3025			realloc		same as realloc=on
3026			noari		do not use PCIe ARI.
3027			pcie_scan_all	Scan all possible PCIe devices.  Otherwise we
3028					only look for one device below a PCIe downstream
3029					port.
3031		pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
3032				Management.
3033			off	Disable ASPM.
3034			force	Enable ASPM even on devices that claim not to support it.
3035				WARNING: Forcing ASPM on may cause system lockups.
3037		pcie_hp=	[PCIE] PCI Express Hotplug driver options:
3038			nomsi	Do not use MSI for PCI Express Native Hotplug (this
3039				makes all PCIe ports use INTx for hotplug services).
3041		pcie_ports=	[PCIE] PCIe ports handling:
3042			auto	Ask the BIOS whether or not to use native PCIe services
3043				associated with PCIe ports (PME, hot-plug, AER).  Use
3044				them only if that is allowed by the BIOS.
3045			native	Use native PCIe services associated with PCIe ports
3046				unconditionally.
3047			compat	Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
3048				ports driver.
3050		pcie_pme=	[PCIE,PM] Native PCIe PME signaling options:
3051			nomsi	Do not use MSI for native PCIe PME signaling (this makes
3052				all PCIe root ports use INTx for all services).
3054		pcmv=		[HW,PCMCIA] BadgePAD 4
3056		pd_ignore_unused
3057				[PM]
3058				Keep all power-domains already enabled by bootloader on,
3059				even if no driver has claimed them. This is useful
3060				for debug and development, but should not be
3061				needed on a platform with proper driver support.
3063		pd.		[PARIDE]
3064				See Documentation/blockdev/paride.txt.
3066		pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
3067				boot time.
3068				Format: { 0 | 1 }
3069				See arch/parisc/kernel/pdc_chassis.c
3071		percpu_alloc=	Select which percpu first chunk allocator to use.
3072				Currently supported values are "embed" and "page".
3073				Archs may support subset or none of the	selections.
3074				See comments in mm/percpu.c for details on each
3075				allocator.  This parameter is primarily	for debugging
3076				and performance comparison.
3078		pf.		[PARIDE]
3079				See Documentation/blockdev/paride.txt.
3081		pg.		[PARIDE]
3082				See Documentation/blockdev/paride.txt.
3084		pirq=		[SMP,APIC] Manual mp-table setup
3085				See Documentation/x86/i386/IO-APIC.txt.
3087		plip=		[PPT,NET] Parallel port network link
3088				Format: { parport<nr> | timid | 0 }
3089				See also Documentation/parport.txt.
3091		pmtmr=		[X86] Manual setup of pmtmr I/O Port.
3092				Override pmtimer IOPort with a hex value.
3093				e.g. pmtmr=0x508
3095		pnp.debug=1	[PNP]
3096				Enable PNP debug messages (depends on the
3097				CONFIG_PNP_DEBUG_MESSAGES option).  Change at run-time
3098				via /sys/module/pnp/parameters/debug.  We always show
3099				current resource usage; turning this on also shows
3100				possible settings and some assignment information.
3102		pnpacpi=	[ACPI]
3103				{ off }
3105		pnpbios=	[ISAPNP]
3106				{ on | off | curr | res | no-curr | no-res }
3108		pnp_reserve_irq=
3109				[ISAPNP] Exclude IRQs for the autoconfiguration
3111		pnp_reserve_dma=
3112				[ISAPNP] Exclude DMAs for the autoconfiguration
3114		pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
3115				Ranges are in pairs (I/O port base and size).
3117		pnp_reserve_mem=
3118				[ISAPNP] Exclude memory regions for the
3119				autoconfiguration.
3120				Ranges are in pairs (memory base and size).
3122		ports=		[IP_VS_FTP] IPVS ftp helper module
3123				Default is 21.
3124				Up to 8 (IP_VS_APP_MAX_PORTS) ports
3125				may be specified.
3126				Format: <port>,<port>....
3128		ppc_strict_facility_enable
3129				[PPC] This option catches any kernel floating point,
3130				Altivec, VSX and SPE outside of regions specifically
3131				allowed (eg kernel_enable_fpu()/kernel_disable_fpu()).
3132				There is some performance impact when enabling this.
3134		print-fatal-signals=
3135				[KNL] debug: print fatal signals
3137				If enabled, warn about various signal handling
3138				related application anomalies: too many signals,
3139				too many POSIX.1 timers, fatal signals causing a
3140				coredump - etc.
3142				If you hit the warning due to signal overflow,
3143				you might want to try "ulimit -i unlimited".
3145				default: off.
3147		printk.always_kmsg_dump=
3148				Trigger kmsg_dump for cases other than kernel oops or
3149				panics
3150				Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
3151				default: disabled
3153		printk.time=	Show timing data prefixed to each printk message line
3154				Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
3156		processor.max_cstate=	[HW,ACPI]
3157				Limit processor to maximum C-state
3158				max_cstate=9 overrides any DMI blacklist limit.
3160		processor.nocst	[HW,ACPI]
3161				Ignore the _CST method to determine C-states,
3162				instead using the legacy FADT method
3164		profile=	[KNL] Enable kernel profiling via /proc/profile
3165				Format: [schedule,]<number>
3166				Param: "schedule" - profile schedule points.
3167				Param: <number> - step/bucket size as a power of 2 for
3168					statistical time based profiling.
3169				Param: "sleep" - profile D-state sleeping (millisecs).
3170					Requires CONFIG_SCHEDSTATS
3171				Param: "kvm" - profile VM exits.
3173		prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk
3174				before loading.
3175				See Documentation/blockdev/ramdisk.txt.
3177		psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
3178				probe for; one of (bare|imps|exps|lifebook|any).
3179		psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
3180				per second.
3181		psmouse.resetafter=	[HW,MOUSE]
3182				Try to reset the device after so many bad packets
3183				(0 = never).
3184		psmouse.resolution=
3185				[HW,MOUSE] Set desired mouse resolution, in dpi.
3186		psmouse.smartscroll=
3187				[HW,MOUSE] Controls Logitech smartscroll autorepeat.
3188				0 = disabled, 1 = enabled (default).
3190		pstore.backend=	Specify the name of the pstore backend to use
3192		pt.		[PARIDE]
3193				See Documentation/blockdev/paride.txt.
3195		pty.legacy_count=
3196				[KNL] Number of legacy pty's. Overwrites compiled-in
3197				default number.
3199		quiet		[KNL] Disable most log messages
3201		r128=		[HW,DRM]
3203		raid=		[HW,RAID]
3204				See Documentation/md.txt.
3206		ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
3207				See Documentation/blockdev/ramdisk.txt.
3209		rcu_nocbs=	[KNL]
3210				In kernels built with CONFIG_RCU_NOCB_CPU=y, set
3211				the specified list of CPUs to be no-callback CPUs.
3212				Invocation of these CPUs' RCU callbacks will
3213				be offloaded to "rcuox/N" kthreads created for
3214				that purpose, where "x" is "b" for RCU-bh, "p"
3215				for RCU-preempt, and "s" for RCU-sched, and "N"
3216				is the CPU number.  This reduces OS jitter on the
3217				offloaded CPUs, which can be useful for HPC and
3218				real-time workloads.  It can also improve energy
3219				efficiency for asymmetric multiprocessors.
3221		rcu_nocb_poll	[KNL]
3222				Rather than requiring that offloaded CPUs
3223				(specified by rcu_nocbs= above) explicitly
3224				awaken the corresponding "rcuoN" kthreads,
3225				make these kthreads poll for callbacks.
3226				This improves the real-time response for the
3227				offloaded CPUs by relieving them of the need to
3228				wake up the corresponding kthread, but degrades
3229				energy efficiency by requiring that the kthreads
3230				periodically wake up to do the polling.
3232		rcutree.blimit=	[KNL]
3233				Set maximum number of finished RCU callbacks to
3234				process in one batch.
3236		rcutree.dump_tree=	[KNL]
3237				Dump the structure of the rcu_node combining tree
3238				out at early boot.  This is used for diagnostic
3239				purposes, to verify correct tree setup.
3241		rcutree.gp_cleanup_delay=	[KNL]
3242				Set the number of jiffies to delay each step of
3243				RCU grace-period cleanup.  This only has effect
3246		rcutree.gp_init_delay=	[KNL]
3247				Set the number of jiffies to delay each step of
3248				RCU grace-period initialization.  This only has
3250				is set.
3252		rcutree.gp_preinit_delay=	[KNL]
3253				Set the number of jiffies to delay each step of
3254				RCU grace-period pre-initialization, that is,
3255				the propagation of recent CPU-hotplug changes up
3256				the rcu_node combining tree.  This only has effect
3259		rcutree.rcu_fanout_exact= [KNL]
3260				Disable autobalancing of the rcu_node combining
3261				tree.  This is used by rcutorture, and might
3262				possibly be useful for architectures having high
3263				cache-to-cache transfer latencies.
3265		rcutree.rcu_fanout_leaf= [KNL]
3266				Change the number of CPUs assigned to each
3267				leaf rcu_node structure.  Useful for very
3268				large systems, which will choose the value 64,
3269				and for NUMA systems with large remote-access
3270				latencies, which will choose a value aligned
3271				with the appropriate hardware boundaries.
3273		rcutree.jiffies_till_sched_qs= [KNL]
3274				Set required age in jiffies for a
3275				given grace period before RCU starts
3276				soliciting quiescent-state help from
3277				rcu_note_context_switch().
3279		rcutree.jiffies_till_first_fqs= [KNL]
3280				Set delay from grace-period initialization to
3281				first attempt to force quiescent states.
3282				Units are jiffies, minimum value is zero,
3283				and maximum value is HZ.
3285		rcutree.jiffies_till_next_fqs= [KNL]
3286				Set delay between subsequent attempts to force
3287				quiescent states.  Units are jiffies, minimum
3288				value is one, and maximum value is HZ.
3290		rcutree.kthread_prio= 	 [KNL,BOOT]
3291				Set the SCHED_FIFO priority of the RCU per-CPU
3292				kthreads (rcuc/N). This value is also used for
3293				the priority of the RCU boost threads (rcub/N)
3294				and for the RCU grace-period kthreads (rcu_bh,
3295				rcu_preempt, and rcu_sched). If RCU_BOOST is
3296				set, valid values are 1-99 and the default is 1
3297				(the least-favored priority).  Otherwise, when
3298				RCU_BOOST is not set, valid values are 0-99 and
3299				the default is zero (non-realtime operation).
3301		rcutree.rcu_nocb_leader_stride= [KNL]
3302				Set the number of NOCB kthread groups, which
3303				defaults to the square root of the number of
3304				CPUs.  Larger numbers reduces the wakeup overhead
3305				on the per-CPU grace-period kthreads, but increases
3306				that same overhead on each group's leader.
3308		rcutree.qhimark= [KNL]
3309				Set threshold of queued RCU callbacks beyond which
3310				batch limiting is disabled.
3312		rcutree.qlowmark= [KNL]
3313				Set threshold of queued RCU callbacks below which
3314				batch limiting is re-enabled.
3316		rcutree.rcu_idle_gp_delay= [KNL]
3317				Set wakeup interval for idle CPUs that have
3318				RCU callbacks (RCU_FAST_NO_HZ=y).
3320		rcutree.rcu_idle_lazy_gp_delay= [KNL]
3321				Set wakeup interval for idle CPUs that have
3322				only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
3323				Lazy RCU callbacks are those which RCU can
3324				prove do nothing more than free memory.
3326		rcuperf.gp_exp= [KNL]
3327				Measure performance of expedited synchronous
3328				grace-period primitives.
3330		rcuperf.holdoff= [KNL]
3331				Set test-start holdoff period.  The purpose of
3332				this parameter is to delay the start of the
3333				test until boot completes in order to avoid
3334				interference.
3336		rcuperf.nreaders= [KNL]
3337				Set number of RCU readers.  The value -1 selects
3338				N, where N is the number of CPUs.  A value
3339				"n" less than -1 selects N-n+1, where N is again
3340				the number of CPUs.  For example, -2 selects N
3341				(the number of CPUs), -3 selects N+1, and so on.
3342				A value of "n" less than or equal to -N selects
3343				a single reader.
3345		rcuperf.nwriters= [KNL]
3346				Set number of RCU writers.  The values operate
3347				the same as for rcuperf.nreaders.
3348				N, where N is the number of CPUs
3350		rcuperf.perf_runnable= [BOOT]
3351				Start rcuperf running at boot time.
3353		rcuperf.shutdown= [KNL]
3354				Shut the system down after performance tests
3355				complete.  This is useful for hands-off automated
3356				testing.
3358		rcuperf.perf_type= [KNL]
3359				Specify the RCU implementation to test.
3361		rcuperf.verbose= [KNL]
3362				Enable additional printk() statements.
3364		rcutorture.cbflood_inter_holdoff= [KNL]
3365				Set holdoff time (jiffies) between successive
3366				callback-flood tests.
3368		rcutorture.cbflood_intra_holdoff= [KNL]
3369				Set holdoff time (jiffies) between successive
3370				bursts of callbacks within a given callback-flood
3371				test.
3373		rcutorture.cbflood_n_burst= [KNL]
3374				Set the number of bursts making up a given
3375				callback-flood test.  Set this to zero to
3376				disable callback-flood testing.
3378		rcutorture.cbflood_n_per_burst= [KNL]
3379				Set the number of callbacks to be registered
3380				in a given burst of a callback-flood test.
3382		rcutorture.fqs_duration= [KNL]
3383				Set duration of force_quiescent_state bursts
3384				in microseconds.
3386		rcutorture.fqs_holdoff= [KNL]
3387				Set holdoff time within force_quiescent_state bursts
3388				in microseconds.
3390		rcutorture.fqs_stutter= [KNL]
3391				Set wait time between force_quiescent_state bursts
3392				in seconds.
3394		rcutorture.gp_cond= [KNL]
3395				Use conditional/asynchronous update-side
3396				primitives, if available.
3398		rcutorture.gp_exp= [KNL]
3399				Use expedited update-side primitives, if available.
3401		rcutorture.gp_normal= [KNL]
3402				Use normal (non-expedited) asynchronous
3403				update-side primitives, if available.
3405		rcutorture.gp_sync= [KNL]
3406				Use normal (non-expedited) synchronous
3407				update-side primitives, if available.  If all
3408				of rcutorture.gp_cond=, rcutorture.gp_exp=,
3409				rcutorture.gp_normal=, and rcutorture.gp_sync=
3410				are zero, rcutorture acts as if is interpreted
3411				they are all non-zero.
3413		rcutorture.n_barrier_cbs= [KNL]
3414				Set callbacks/threads for rcu_barrier() testing.
3416		rcutorture.nfakewriters= [KNL]
3417				Set number of concurrent RCU writers.  These just
3418				stress RCU, they don't participate in the actual
3419				test, hence the "fake".
3421		rcutorture.nreaders= [KNL]
3422				Set number of RCU readers.  The value -1 selects
3423				N-1, where N is the number of CPUs.  A value
3424				"n" less than -1 selects N-n-2, where N is again
3425				the number of CPUs.  For example, -2 selects N
3426				(the number of CPUs), -3 selects N+1, and so on.
3428		rcutorture.object_debug= [KNL]
3429				Enable debug-object double-call_rcu() testing.
3431		rcutorture.onoff_holdoff= [KNL]
3432				Set time (s) after boot for CPU-hotplug testing.
3434		rcutorture.onoff_interval= [KNL]
3435				Set time (s) between CPU-hotplug operations, or
3436				zero to disable CPU-hotplug testing.
3438		rcutorture.shuffle_interval= [KNL]
3439				Set task-shuffle interval (s).  Shuffling tasks
3440				allows some CPUs to go into dyntick-idle mode
3441				during the rcutorture test.
3443		rcutorture.shutdown_secs= [KNL]
3444				Set time (s) after boot system shutdown.  This
3445				is useful for hands-off automated testing.
3447		rcutorture.stall_cpu= [KNL]
3448				Duration of CPU stall (s) to test RCU CPU stall
3449				warnings, zero to disable.
3451		rcutorture.stall_cpu_holdoff= [KNL]
3452				Time to wait (s) after boot before inducing stall.
3454		rcutorture.stat_interval= [KNL]
3455				Time (s) between statistics printk()s.
3457		rcutorture.stutter= [KNL]
3458				Time (s) to stutter testing, for example, specifying
3459				five seconds causes the test to run for five seconds,
3460				wait for five seconds, and so on.  This tests RCU's
3461				ability to transition abruptly to and from idle.
3463		rcutorture.test_boost= [KNL]
3464				Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
3465				"Maybe" means test if the RCU implementation
3466				under test support RCU priority boosting.
3468		rcutorture.test_boost_duration= [KNL]
3469				Duration (s) of each individual boost test.
3471		rcutorture.test_boost_interval= [KNL]
3472				Interval (s) between each boost test.
3474		rcutorture.test_no_idle_hz= [KNL]
3475				Test RCU's dyntick-idle handling.  See also the
3476				rcutorture.shuffle_interval parameter.
3478		rcutorture.torture_runnable= [BOOT]
3479				Start rcutorture running at boot time.
3481		rcutorture.torture_type= [KNL]
3482				Specify the RCU implementation to test.
3484		rcutorture.verbose= [KNL]
3485				Enable additional printk() statements.
3487		rcupdate.rcu_cpu_stall_suppress= [KNL]
3488				Suppress RCU CPU stall warning messages.
3490		rcupdate.rcu_cpu_stall_timeout= [KNL]
3491				Set timeout for RCU CPU stall warning messages.
3493		rcupdate.rcu_expedited= [KNL]
3494				Use expedited grace-period primitives, for
3495				example, synchronize_rcu_expedited() instead
3496				of synchronize_rcu().  This reduces latency,
3497				but can increase CPU utilization, degrade
3498				real-time latency, and degrade energy efficiency.
3499				No effect on CONFIG_TINY_RCU kernels.
3501		rcupdate.rcu_normal= [KNL]
3502				Use only normal grace-period primitives,
3503				for example, synchronize_rcu() instead of
3504				synchronize_rcu_expedited().  This improves
3505				real-time latency, CPU utilization, and
3506				energy efficiency, but can expose users to
3507				increased grace-period latency.  This parameter
3508				overrides rcupdate.rcu_expedited.  No effect on
3509				CONFIG_TINY_RCU kernels.
3511		rcupdate.rcu_normal_after_boot= [KNL]
3512				Once boot has completed (that is, after
3513				rcu_end_inkernel_boot() has been invoked), use
3514				only normal grace-period primitives.  No effect
3515				on CONFIG_TINY_RCU kernels.
3517		rcupdate.rcu_task_stall_timeout= [KNL]
3518				Set timeout in jiffies for RCU task stall warning
3519				messages.  Disable with a value less than or equal
3520				to zero.
3522		rcupdate.rcu_self_test= [KNL]
3523				Run the RCU early boot self tests
3525		rcupdate.rcu_self_test_bh= [KNL]
3526				Run the RCU bh early boot self tests
3528		rcupdate.rcu_self_test_sched= [KNL]
3529				Run the RCU sched early boot self tests
3531		rdinit=		[KNL]
3532				Format: <full_path>
3533				Run specified binary instead of /init from the ramdisk,
3534				used for early userspace startup. See initrd.
3536		reboot=		[KNL]
3537				Format (x86 or x86_64):
3538					[w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
3539					[[,]s[mp]#### \
3540					[[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
3541					[[,]f[orce]
3542				Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
3543				      reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
3544				      reboot_force is either force or not specified,
3545				      reboot_cpu is s[mp]#### with #### being the processor
3546						to be used for rebooting.
3548		relax_domain_level=
3549				[KNL, SMP] Set scheduler's default relax_domain_level.
3550				See Documentation/cgroups/cpusets.txt.
3552		relative_sleep_states=
3553				[SUSPEND] Use sleep state labeling where the deepest
3554				state available other than hibernation is always "mem".
3555				Format: { "0" | "1" }
3556				0 -- Traditional sleep state labels.
3557				1 -- Relative sleep state labels.
3559		reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area
3561		reservetop=	[X86-32]
3562				Format: nn[KMG]
3563				Reserves a hole at the top of the kernel virtual
3564				address space.
3566		reservelow=	[X86]
3567				Format: nn[K]
3568				Set the amount of memory to reserve for BIOS at
3569				the bottom of the address space.
3571		reset_devices	[KNL] Force drivers to reset the underlying device
3572				during initialization.
3574		resume=		[SWSUSP]
3575				Specify the partition device for software suspend
3576				Format:
3577				{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
3579		resume_offset=	[SWSUSP]
3580				Specify the offset from the beginning of the partition
3581				given by "resume=" at which the swap header is located,
3582				in <PAGE_SIZE> units (needed only for swap files).
3583				See  Documentation/power/swsusp-and-swap-files.txt
3585		resumedelay=	[HIBERNATION] Delay (in seconds) to pause before attempting to
3586				read the resume files
3588		resumewait	[HIBERNATION] Wait (indefinitely) for resume device to show up.
3589				Useful for devices that are detected asynchronously
3590				(e.g. USB and MMC devices).
3592		hibernate=	[HIBERNATION]
3593			noresume	Don't check if there's a hibernation image
3594					present during boot.
3595			nocompress	Don't compress/decompress hibernation images.
3596			no		Disable hibernation and resume.
3598		retain_initrd	[RAM] Keep initrd memory after extraction
3600		rfkill.default_state=
3601			0	"airplane mode".  All wifi, bluetooth, wimax, gps, fm,
3602				etc. communication is blocked by default.
3603			1	Unblocked.
3605		rfkill.master_switch_mode=
3606			0	The "airplane mode" button does nothing.
3607			1	The "airplane mode" button toggles between everything
3608				blocked and the previous configuration.
3609			2	The "airplane mode" button toggles between everything
3610				blocked and everything unblocked.
3612		rhash_entries=	[KNL,NET]
3613				Set number of hash buckets for route cache
3615		ro		[KNL] Mount root device read-only on boot
3617		rodata=		[KNL]
3618			on	Mark read-only kernel memory as read-only (default).
3619			off	Leave read-only kernel memory writable for debugging.
3621		rockchip.usb_uart
3622				Enable the uart passthrough on the designated usb port
3623				on Rockchip SoCs. When active, the signals of the
3624				debug-uart get routed to the D+ and D- pins of the usb
3625				port and the regular usb controller gets disabled.
3627		root=		[KNL] Root filesystem
3628				See name_to_dev_t comment in init/do_mounts.c.
3630		rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
3631				mount the root filesystem
3633		rootflags=	[KNL] Set root filesystem mount option string
3635		rootfstype=	[KNL] Set root filesystem type
3637		rootwait	[KNL] Wait (indefinitely) for root device to show up.
3638				Useful for devices that are detected asynchronously
3639				(e.g. USB and MMC devices).
3641		rproc_mem=nn[KMG][@address]
3642				[KNL,ARM,CMA] Remoteproc physical memory block.
3643				Memory area to be used by remote processor image,
3644				managed by CMA.
3646		rw		[KNL] Mount root device read-write on boot
3648		S		[KNL] Run init in single mode
3650		s390_iommu=	[HW,S390]
3651				Set s390 IOTLB flushing mode
3652			strict
3653				With strict flushing every unmap operation will result in
3654				an IOTLB flush. Default is lazy flushing before reuse,
3655				which is faster.
3657		sa1100ir	[NET]
3658				See drivers/net/irda/sa1100_ir.c.
3660		sbni=		[NET] Granch SBNI12 leased line adapter
3662		sched_debug	[KNL] Enables verbose scheduler debug messages.
3664		schedstats=	[KNL,X86] Enable or disable scheduled statistics.
3665				Allowed values are enable and disable. This feature
3666				incurs a small amount of overhead in the scheduler
3667				but is useful for debugging and performance tuning.
3669		skew_tick=	[KNL] Offset the periodic timer tick per cpu to mitigate
3670				xtime_lock contention on larger systems, and/or RCU lock
3671				contention on all systems with CONFIG_MAXSMP set.
3672				Format: { "0" | "1" }
3673				0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
3674				1 -- enable.
3675				Note: increases power consumption, thus should only be
3676				enabled if running jitter sensitive (HPC/RT) workloads.
3678		security=	[SECURITY] Choose a security module to enable at boot.
3679				If this boot parameter is not specified, only the first
3680				security module asking for security registration will be
3681				loaded. An invalid security module name will be treated
3682				as if no module has been chosen.
3684		selinux=	[SELINUX] Disable or enable SELinux at boot time.
3685				Format: { "0" | "1" }
3686				See security/selinux/Kconfig help text.
3687				0 -- disable.
3688				1 -- enable.
3689				Default value is set via kernel config option.
3690				If enabled at boot time, /selinux/disable can be used
3691				later to disable prior to initial policy load.
3693		apparmor=	[APPARMOR] Disable or enable AppArmor at boot time
3694				Format: { "0" | "1" }
3695				See security/apparmor/Kconfig help text
3696				0 -- disable.
3697				1 -- enable.
3698				Default value is set via kernel config option.
3700		serialnumber	[BUGS=X86-32]
3702		shapers=	[NET]
3703				Maximal number of shapers.
3705		show_msr=	[x86] show boot-time MSR settings
3706				Format: { <integer> }
3707				Show boot-time (BIOS-initialized) MSR settings.
3708				The parameter means the number of CPUs to show,
3709				for example 1 means boot CPU only.
3711		simeth=		[IA-64]
3712		simscsi=
3714		slram=		[HW,MTD]
3716		slab_nomerge	[MM]
3717				Disable merging of slabs with similar size. May be
3718				necessary if there is some reason to distinguish
3719				allocs to different slabs. Debug options disable
3720				merging on their own.
3721				For more information see Documentation/vm/slub.txt.
3723		slab_max_order=	[MM, SLAB]
3724				Determines the maximum allowed order for slabs.
3725				A high setting may cause OOMs due to memory
3726				fragmentation.  Defaults to 1 for systems with
3727				more than 32MB of RAM, 0 otherwise.
3729		slub_debug[=options[,slabs]]	[MM, SLUB]
3730				Enabling slub_debug allows one to determine the
3731				culprit if slab objects become corrupted. Enabling
3732				slub_debug can create guard zones around objects and
3733				may poison objects when not in use. Also tracks the
3734				last alloc / free. For more information see
3735				Documentation/vm/slub.txt.
3737		slub_max_order= [MM, SLUB]
3738				Determines the maximum allowed order for slabs.
3739				A high setting may cause OOMs due to memory
3740				fragmentation. For more information see
3741				Documentation/vm/slub.txt.
3743		slub_min_objects=	[MM, SLUB]
3744				The minimum number of objects per slab. SLUB will
3745				increase the slab order up to slub_max_order to
3746				generate a sufficiently large slab able to contain
3747				the number of objects indicated. The higher the number
3748				of objects the smaller the overhead of tracking slabs
3749				and the less frequently locks need to be acquired.
3750				For more information see Documentation/vm/slub.txt.
3752		slub_min_order=	[MM, SLUB]
3753				Determines the minimum page order for slabs. Must be
3754				lower than slub_max_order.
3755				For more information see Documentation/vm/slub.txt.
3757		slub_nomerge	[MM, SLUB]
3758				Same with slab_nomerge. This is supported for legacy.
3759				See slab_nomerge for more information.
3761		smart2=		[HW]
3762				Format: <io1>[,<io2>[,...,<io8>]]
3764		smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
3765		smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
3766		smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
3767		smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
3768		smsc-ircc2.ircc_irq=	[HW] IRQ line
3769		smsc-ircc2.ircc_dma=	[HW] DMA channel
3770		smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
3771					0: Toshiba Satellite 1800 (GP data pin select)
3772					1: Fast pin select (default)
3773					2: ATC IRMode
3775		smt		[KNL,S390] Set the maximum number of threads (logical
3776				CPUs) to use per physical CPU on systems capable of
3777				symmetric multithreading (SMT). Will be capped to the
3778				actual hardware limit.
3779				Format: <integer>
3780				Default: -1 (no limit)
3782		softlockup_panic=
3783				[KNL] Should the soft-lockup detector generate panics.
3784				Format: <integer>
3786		softlockup_all_cpu_backtrace=
3787				[KNL] Should the soft-lockup detector generate
3788				backtraces on all cpus.
3789				Format: <integer>
3791		sonypi.*=	[HW] Sony Programmable I/O Control Device driver
3792				See Documentation/laptops/sonypi.txt
3794		spia_io_base=	[HW,MTD]
3795		spia_fio_base=
3796		spia_pedr=
3797		spia_peddr=
3799		stacktrace	[FTRACE]
3800				Enabled the stack tracer on boot up.
3802		stacktrace_filter=[function-list]
3803				[FTRACE] Limit the functions that the stack tracer
3804				will trace at boot up. function-list is a comma separated
3805				list of functions. This list can be changed at run
3806				time by the stack_trace_filter file in the debugfs
3807				tracing directory. Note, this enables stack tracing
3808				and the stacktrace above is not needed.
3810		sti=		[PARISC,HW]
3811				Format: <num>
3812				Set the STI (builtin display/keyboard on the HP-PARISC
3813				machines) console (graphic card) which should be used
3814				as the initial boot-console.
3815				See also comment in drivers/video/console/sticore.c.
3817		sti_font=	[HW]
3818				See comment in drivers/video/console/sticore.c.
3820		stifb=		[HW]
3821				Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
3823		sunrpc.min_resvport=
3824		sunrpc.max_resvport=
3825				[NFS,SUNRPC]
3826				SunRPC servers often require that client requests
3827				originate from a privileged port (i.e. a port in the
3828				range 0 < portnr < 1024).
3829				An administrator who wishes to reserve some of these
3830				ports for other uses may adjust the range that the
3831				kernel's sunrpc client considers to be privileged
3832				using these two parameters to set the minimum and
3833				maximum port values.
3835		sunrpc.pool_mode=
3836				[NFS]
3837				Control how the NFS server code allocates CPUs to
3838				service thread pools.  Depending on how many NICs
3839				you have and where their interrupts are bound, this
3840				option will affect which CPUs will do NFS serving.
3841				Note: this parameter cannot be changed while the
3842				NFS server is running.
3844				auto	    the server chooses an appropriate mode
3845					    automatically using heuristics
3846				global	    a single global pool contains all CPUs
3847				percpu	    one pool for each CPU
3848				pernode	    one pool for each NUMA node (equivalent
3849					    to global on non-NUMA machines)
3851		sunrpc.tcp_slot_table_entries=
3852		sunrpc.udp_slot_table_entries=
3853				[NFS,SUNRPC]
3854				Sets the upper limit on the number of simultaneous
3855				RPC calls that can be sent from the client to a
3856				server. Increasing these values may allow you to
3857				improve throughput, but will also increase the
3858				amount of memory reserved for use by the client.
3860		suspend.pm_test_delay=
3861				[SUSPEND]
3862				Sets the number of seconds to remain in a suspend test
3863				mode before resuming the system (see
3864				/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
3865				is set. Default value is 5.
3867		swapaccount=[0|1]
3868				[KNL] Enable accounting of swap in memory resource
3869				controller if no parameter or 1 is given or disable
3870				it if 0 is given (See Documentation/cgroups/memory.txt)
3872		swiotlb=	[ARM,IA-64,PPC,MIPS,X86]
3873				Format: { <int> | force }
3874				<int> -- Number of I/O TLB slabs
3875				force -- force using of bounce buffers even if they
3876				         wouldn't be automatically used by the kernel
3878		switches=	[HW,M68k]
3880		sysfs.deprecated=0|1 [KNL]
3881				Enable/disable old style sysfs layout for old udev
3882				on older distributions. When this option is enabled
3883				very new udev will not work anymore. When this option
3884				is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
3885				in older udev will not work anymore.
3886				Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
3887				the kernel configuration.
3889		sysrq_always_enabled
3890				[KNL]
3891				Ignore sysrq setting - this boot parameter will
3892				neutralize any effect of /proc/sys/kernel/sysrq.
3893				Useful for debugging.
3895		tcpmhash_entries= [KNL,NET]
3896				Set the number of tcp_metrics_hash slots.
3897				Default value is 8192 or 16384 depending on total
3898				ram pages. This is used to specify the TCP metrics
3899				cache size. See Documentation/networking/ip-sysctl.txt
3900				"tcp_no_metrics_save" section for more details.
3902		tdfx=		[HW,DRM]
3904		test_suspend=	[SUSPEND][,N]
3905				Specify "mem" (for Suspend-to-RAM) or "standby" (for
3906				standby suspend) or "freeze" (for suspend type freeze)
3907				as the system sleep state during system startup with
3908				the optional capability to repeat N number of times.
3909				The system is woken from this state using a
3910				wakeup-capable RTC alarm.
3912		thash_entries=	[KNL,NET]
3913				Set number of hash buckets for TCP connection
3915		thermal.act=	[HW,ACPI]
3916				-1: disable all active trip points in all thermal zones
3917				<degrees C>: override all lowest active trip points
3919		thermal.crt=	[HW,ACPI]
3920				-1: disable all critical trip points in all thermal zones
3921				<degrees C>: override all critical trip points
3923		thermal.nocrt=	[HW,ACPI]
3924				Set to disable actions on ACPI thermal zone
3925				critical and hot trip points.
3927		thermal.off=	[HW,ACPI]
3928				1: disable ACPI thermal control
3930		thermal.psv=	[HW,ACPI]
3931				-1: disable all passive trip points
3932				<degrees C>: override all passive trip points to this
3933				value
3935		thermal.tzp=	[HW,ACPI]
3936				Specify global default ACPI thermal zone polling rate
3937				<deci-seconds>: poll all this frequency
3938				0: no polling (default)
3940		threadirqs	[KNL]
3941				Force threading of all interrupt handlers except those
3942				marked explicitly IRQF_NO_THREAD.
3944		tmem		[KNL,XEN]
3945				Enable the Transcendent memory driver if built-in.
3947		tmem.cleancache=0|1 [KNL, XEN]
3948				Default is on (1). Disable the usage of the cleancache
3949				API to send anonymous pages to the hypervisor.
3951		tmem.frontswap=0|1 [KNL, XEN]
3952				Default is on (1). Disable the usage of the frontswap
3953				API to send swap pages to the hypervisor. If disabled
3954				the selfballooning and selfshrinking are force disabled.
3956		tmem.selfballooning=0|1 [KNL, XEN]
3957				Default is on (1). Disable the driving of swap pages
3958				to the hypervisor.
3960		tmem.selfshrinking=0|1 [KNL, XEN]
3961				Default is on (1). Partial swapoff that immediately
3962				transfers pages from Xen hypervisor back to the
3963				kernel based on different criteria.
3965		topology=	[S390]
3966				Format: {off | on}
3967				Specify if the kernel should make use of the cpu
3968				topology information if the hardware supports this.
3969				The scheduler will make use of this information and
3970				e.g. base its process migration decisions on it.
3971				Default is on.
3973		topology_updates= [KNL, PPC, NUMA]
3974				Format: {off}
3975				Specify if the kernel should ignore (off)
3976				topology updates sent by the hypervisor to this
3977				LPAR.
3979		tp720=		[HW,PS2]
3981		tpm_suspend_pcr=[HW,TPM]
3982				Format: integer pcr id
3983				Specify that at suspend time, the tpm driver
3984				should extend the specified pcr with zeros,
3985				as a workaround for some chips which fail to
3986				flush the last written pcr on TPM_SaveState.
3987				This will guarantee that all the other pcrs
3988				are saved.
3990		trace_buf_size=nn[KMG]
3991				[FTRACE] will set tracing buffer size on each cpu.
3993		trace_event=[event-list]
3994				[FTRACE] Set and start specified trace events in order
3995				to facilitate early boot debugging.
3996				See also Documentation/trace/events.txt
3998		trace_options=[option-list]
3999				[FTRACE] Enable or disable tracer options at boot.
4000				The option-list is a comma delimited list of options
4001				that can be enabled or disabled just as if you were
4002				to echo the option name into
4004				    /sys/kernel/debug/tracing/trace_options
4006				For example, to enable stacktrace option (to dump the
4007				stack trace of each event), add to the command line:
4009				      trace_options=stacktrace
4011				See also Documentation/trace/ftrace.txt "trace options"
4012				section.
4014		tp_printk[FTRACE]
4015				Have the tracepoints sent to printk as well as the
4016				tracing ring buffer. This is useful for early boot up
4017				where the system hangs or reboots and does not give the
4018				option for reading the tracing buffer or performing a
4019				ftrace_dump_on_oops.
4021				To turn off having tracepoints sent to printk,
4022				 echo 0 > /proc/sys/kernel/tracepoint_printk
4023				Note, echoing 1 into this file without the
4024				tracepoint_printk kernel cmdline option has no effect.
4026				** CAUTION **
4028				Having tracepoints sent to printk() and activating high
4029				frequency tracepoints such as irq or sched, can cause
4030				the system to live lock.
4032		traceoff_on_warning
4033				[FTRACE] enable this option to disable tracing when a
4034				warning is hit. This turns off "tracing_on". Tracing can
4035				be enabled again by echoing '1' into the "tracing_on"
4036				file located in /sys/kernel/debug/tracing/
4038				This option is useful, as it disables the trace before
4039				the WARNING dump is called, which prevents the trace to
4040				be filled with content caused by the warning output.
4042				This option can also be set at run time via the sysctl
4043				option:  kernel/traceoff_on_warning
4045		transparent_hugepage=
4046				[KNL]
4047				Format: [always|madvise|never]
4048				Can be used to control the default behavior of the system
4049				with respect to transparent hugepages.
4050				See Documentation/vm/transhuge.txt for more details.
4052		tsc=		Disable clocksource stability checks for TSC.
4053				Format: <string>
4054				[x86] reliable: mark tsc clocksource as reliable, this
4055				disables clocksource verification at runtime, as well
4056				as the stability checks done at bootup.	Used to enable
4057				high-resolution timer mode on older hardware, and in
4058				virtualized environment.
4059				[x86] noirqtime: Do not use TSC to do irq accounting.
4060				Used to run time disable IRQ_TIME_ACCOUNTING on any
4061				platforms where RDTSC is slow and this accounting
4062				can add overhead.
4064		turbografx.map[2|3]=	[HW,JOY]
4065				TurboGraFX parallel port interface
4066				Format:
4067				<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
4068				See also Documentation/input/joystick-parport.txt
4070		udbg-immortal	[PPC] When debugging early kernel crashes that
4071				happen after console_init() and before a proper 
4072				console driver takes over, this boot options might
4073				help "seeing" what's going on.
4075		uhash_entries=	[KNL,NET]
4076				Set number of hash buckets for UDP/UDP-Lite connections
4078		uhci-hcd.ignore_oc=
4079				[USB] Ignore overcurrent events (default N).
4080				Some badly-designed motherboards generate lots of
4081				bogus events, for ports that aren't wired to
4082				anything.  Set this parameter to avoid log spamming.
4083				Note that genuine overcurrent events won't be
4084				reported either.
4086		unknown_nmi_panic
4087				[X86] Cause panic on unknown NMI.
4089		usbcore.authorized_default=
4090				[USB] Default USB device authorization:
4091				(default -1 = authorized except for wireless USB,
4092				0 = not authorized, 1 = authorized)
4094		usbcore.autosuspend=
4095				[USB] The autosuspend time delay (in seconds) used
4096				for newly-detected USB devices (default 2).  This
4097				is the time required before an idle device will be
4098				autosuspended.  Devices for which the delay is set
4099				to a negative value won't be autosuspended at all.
4101		usbcore.usbfs_snoop=
4102				[USB] Set to log all usbfs traffic (default 0 = off).
4104		usbcore.usbfs_snoop_max=
4105				[USB] Maximum number of bytes to snoop in each URB
4106				(default = 65536).
4108		usbcore.blinkenlights=
4109				[USB] Set to cycle leds on hubs (default 0 = off).
4111		usbcore.old_scheme_first=
4112				[USB] Start with the old device initialization
4113				scheme (default 0 = off).
4115		usbcore.usbfs_memory_mb=
4116				[USB] Memory limit (in MB) for buffers allocated by
4117				usbfs (default = 16, 0 = max = 2047).
4119		usbcore.use_both_schemes=
4120				[USB] Try the other device initialization scheme
4121				if the first one fails (default 1 = enabled).
4123		usbcore.initial_descriptor_timeout=
4124				[USB] Specifies timeout for the initial 64-byte
4125	                        USB_REQ_GET_DESCRIPTOR request in milliseconds
4126				(default 5000 = 5.0 seconds).
4128		usbcore.nousb	[USB] Disable the USB subsystem
4130		usbhid.mousepoll=
4131				[USBHID] The interval which mice are to be polled at.
4133		usb-storage.delay_use=
4134				[UMS] The delay in seconds before a new device is
4135				scanned for Logical Units (default 1).
4137		usb-storage.quirks=
4138				[UMS] A list of quirks entries to supplement or
4139				override the built-in unusual_devs list.  List
4140				entries are separated by commas.  Each entry has
4141				the form VID:PID:Flags where VID and PID are Vendor
4142				and Product ID values (4-digit hex numbers) and
4143				Flags is a set of characters, each corresponding
4144				to a common usb-storage quirk flag as follows:
4145					a = SANE_SENSE (collect more than 18 bytes
4146						of sense data);
4147					b = BAD_SENSE (don't collect more than 18
4148						bytes of sense data);
4149					c = FIX_CAPACITY (decrease the reported
4150						device capacity by one sector);
4151					d = NO_READ_DISC_INFO (don't use
4152						READ_DISC_INFO command);
4153					e = NO_READ_CAPACITY_16 (don't use
4154						READ_CAPACITY_16 command);
4155					f = NO_REPORT_OPCODES (don't use report opcodes
4156						command, uas only);
4157					g = MAX_SECTORS_240 (don't transfer more than
4158						240 sectors at a time, uas only);
4159					h = CAPACITY_HEURISTICS (decrease the
4160						reported device capacity by one
4161						sector if the number is odd);
4162					i = IGNORE_DEVICE (don't bind to this
4163						device);
4164					j = NO_REPORT_LUNS (don't use report luns
4165						command, uas only);
4166					l = NOT_LOCKABLE (don't try to lock and
4167						unlock ejectable media);
4168					m = MAX_SECTORS_64 (don't transfer more
4169						than 64 sectors = 32 KB at a time);
4170					n = INITIAL_READ10 (force a retry of the
4171						initial READ(10) command);
4172					o = CAPACITY_OK (accept the capacity
4173						reported by the device);
4174					p = WRITE_CACHE (the device cache is ON
4175						by default);
4176					r = IGNORE_RESIDUE (the device reports
4177						bogus residue values);
4178					s = SINGLE_LUN (the device has only one
4179						Logical Unit);
4180					t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
4181						commands, uas only);
4182					u = IGNORE_UAS (don't bind to the uas driver);
4183					w = NO_WP_DETECT (don't test whether the
4184						medium is write-protected).
4185				Example: quirks=0419:aaf5:rl,0421:0433:rc
4187		user_debug=	[KNL,ARM]
4188				Format: <int>
4189				See arch/arm/Kconfig.debug help text.
4190					 1 - undefined instruction events
4191					 2 - system calls
4192					 4 - invalid data aborts
4193					 8 - SIGSEGV faults
4194					16 - SIGBUS faults
4195				Example: user_debug=31
4197		userpte=
4198				[X86] Flags controlling user PTE allocations.
4200					nohigh = do not allocate PTE pages in
4201						HIGHMEM regardless of setting
4202						of CONFIG_HIGHPTE.
4204		vdso=		[X86,SH]
4205				On X86_32, this is an alias for vdso32=.  Otherwise:
4207				vdso=1: enable VDSO (the default)
4208				vdso=0: disable VDSO mapping
4210		vdso32=		[X86] Control the 32-bit vDSO
4211				vdso32=1: enable 32-bit VDSO
4212				vdso32=0 or vdso32=2: disable 32-bit VDSO
4214				See the help text for CONFIG_COMPAT_VDSO for more
4215				details.  If CONFIG_COMPAT_VDSO is set, the default is
4216				vdso32=0; otherwise, the default is vdso32=1.
4218				For compatibility with older kernels, vdso32=2 is an
4219				alias for vdso32=0.
4221				Try vdso32=0 if you encounter an error that says:
4222				dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
4224		vector=		[IA-64,SMP]
4225				vector=percpu: enable percpu vector domain
4227		video=		[FB] Frame buffer configuration
4228				See Documentation/fb/modedb.txt.
4230		video.brightness_switch_enabled= [0,1]
4231				If set to 1, on receiving an ACPI notify event
4232				generated by hotkey, video driver will adjust brightness
4233				level and then send out the event to user space through
4234				the allocated input device; If set to 0, video driver
4235				will only send out the event without touching backlight
4236				brightness level.
4237				default: 1
4239		virtio_mmio.device=
4240				[VMMIO] Memory mapped virtio (platform) device.
4242					<size>@<baseaddr>:<irq>[:<id>]
4243				where:
4244					<size>     := size (can use standard suffixes
4245							like K, M and G)
4246					<baseaddr> := physical base address
4247					<irq>      := interrupt number (as passed to
4248							request_irq())
4249					<id>       := (optional) platform device id
4250				example:
4251					virtio_mmio.device=1K@0x100b0000:48:7
4253				Can be used multiple times for multiple devices.
4255		vga=		[BOOT,X86-32] Select a particular video mode
4256				See Documentation/x86/boot.txt and
4257				Documentation/svga.txt.
4258				Use vga=ask for menu.
4259				This is actually a boot loader parameter; the value is
4260				passed to the kernel using a special protocol.
4262		vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
4263				size of <nn>. This can be used to increase the
4264				minimum size (128MB on x86). It can also be used to
4265				decrease the size and leave more room for directly
4266				mapped kernel RAM.
4268		vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
4269				Format: <command>
4271		vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
4272				Format: <command>
4274		vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
4275				Format: <command>
4277		vsyscall=	[X86-64]
4278				Controls the behavior of vsyscalls (i.e. calls to
4279				fixed addresses of 0xffffffffff600x00 from legacy
4280				code).  Most statically-linked binaries and older
4281				versions of glibc use these calls.  Because these
4282				functions are at fixed addresses, they make nice
4283				targets for exploits that can control RIP.
4285				emulate     [default] Vsyscalls turn into traps and are
4286				            emulated reasonably safely.
4288				native      Vsyscalls are native syscall instructions.
4289				            This is a little bit faster than trapping
4290				            and makes a few dynamic recompilers work
4291				            better than they would in emulation mode.
4292				            It also makes exploits much easier to write.
4294				none        Vsyscalls don't work at all.  This makes
4295				            them quite hard to use for exploits but
4296				            might break your system.
4298		vt.color=	[VT] Default text color.
4299				Format: 0xYX, X = foreground, Y = background.
4300				Default: 0x07 = light gray on black.
4302		vt.cur_default=	[VT] Default cursor shape.
4303				Format: 0xCCBBAA, where AA, BB, and CC are the same as
4304				the parameters of the <Esc>[?A;B;Cc escape sequence;
4305				see VGA-softcursor.txt. Default: 2 = underline.
4307		vt.default_blu=	[VT]
4308				Format: <blue0>,<blue1>,<blue2>,...,<blue15>
4309				Change the default blue palette of the console.
4310				This is a 16-member array composed of values
4311				ranging from 0-255.
4313		vt.default_grn=	[VT]
4314				Format: <green0>,<green1>,<green2>,...,<green15>
4315				Change the default green palette of the console.
4316				This is a 16-member array composed of values
4317				ranging from 0-255.
4319		vt.default_red=	[VT]
4320				Format: <red0>,<red1>,<red2>,...,<red15>
4321				Change the default red palette of the console.
4322				This is a 16-member array composed of values
4323				ranging from 0-255.
4325		vt.default_utf8=
4326				[VT]
4327				Format=<0|1>
4328				Set system-wide default UTF-8 mode for all tty's.
4329				Default is 1, i.e. UTF-8 mode is enabled for all
4330				newly opened terminals.
4332		vt.global_cursor_default=
4333				[VT]
4334				Format=<-1|0|1>
4335				Set system-wide default for whether a cursor
4336				is shown on new VTs. Default is -1,
4337				i.e. cursors will be created by default unless
4338				overridden by individual drivers. 0 will hide
4339				cursors, 1 will display them.
4341		vt.italic=	[VT] Default color for italic text; 0-15.
4342				Default: 2 = green.
4344		vt.underline=	[VT] Default color for underlined text; 0-15.
4345				Default: 3 = cyan.
4347		watchdog timers	[HW,WDT] For information on watchdog timers,
4348				see Documentation/watchdog/watchdog-parameters.txt
4349				or other driver-specific files in the
4350				Documentation/watchdog/ directory.
4352		workqueue.watchdog_thresh=
4353				If CONFIG_WQ_WATCHDOG is configured, workqueue can
4354				warn stall conditions and dump internal state to
4355				help debugging.  0 disables workqueue stall
4356				detection; otherwise, it's the stall threshold
4357				duration in seconds.  The default value is 30 and
4358				it can be updated at runtime by writing to the
4359				corresponding sysfs file.
4361		workqueue.disable_numa
4362				By default, all work items queued to unbound
4363				workqueues are affine to the NUMA nodes they're
4364				issued on, which results in better behavior in
4365				general.  If NUMA affinity needs to be disabled for
4366				whatever reason, this option can be used.  Note
4367				that this also can be controlled per-workqueue for
4368				workqueues visible under /sys/bus/workqueue/.
4370		workqueue.power_efficient
4371				Per-cpu workqueues are generally preferred because
4372				they show better performance thanks to cache
4373				locality; unfortunately, per-cpu workqueues tend to
4374				be more power hungry than unbound workqueues.
4376				Enabling this makes the per-cpu workqueues which
4377				were observed to contribute significantly to power
4378				consumption unbound, leading to measurably lower
4379				power usage at the cost of small performance
4380				overhead.
4382				The default value of this parameter is determined by
4383				the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
4385		workqueue.debug_force_rr_cpu
4386				Workqueue used to implicitly guarantee that work
4387				items queued without explicit CPU specified are put
4388				on the local CPU.  This guarantee is no longer true
4389				and while local CPU is still preferred work items
4390				may be put on foreign CPUs.  This debug option
4391				forces round-robin CPU selection to flush out
4392				usages which depend on the now broken guarantee.
4393				When enabled, memory and cache locality will be
4394				impacted.
4396		x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
4397				default x2apic cluster mode on platforms
4398				supporting x2apic.
4400		x86_intel_mid_timer= [X86-32,APBT]
4401				Choose timer option for x86 Intel MID platform.
4402				Two valid options are apbt timer only and lapic timer
4403				plus one apbt timer for broadcast timer.
4404				x86_intel_mid_timer=apbt_only | lapic_and_apbt
4406		xen_512gb_limit		[KNL,X86-64,XEN]
4407				Restricts the kernel running paravirtualized under Xen
4408				to use only up to 512 GB of RAM. The reason to do so is
4409				crash analysis tools and Xen tools for doing domain
4410				save/restore/migration must be enabled to handle larger
4411				domains.
4413		xen_emul_unplug=		[HW,X86,XEN]
4414				Unplug Xen emulated devices
4415				Format: [unplug0,][unplug1]
4416				ide-disks -- unplug primary master IDE devices
4417				aux-ide-disks -- unplug non-primary-master IDE devices
4418				nics -- unplug network devices
4419				all -- unplug all emulated devices (NICs and IDE disks)
4420				unnecessary -- unplugging emulated devices is
4421					unnecessary even if the host did not respond to
4422					the unplug protocol
4423				never -- do not unplug even if version check succeeds
4425		xen_nopvspin	[X86,XEN]
4426				Disables the ticketlock slowpath using Xen PV
4427				optimizations.
4429		xen_nopv	[X86]
4430				Disables the PV optimizations forcing the HVM guest to
4431				run as generic HVM guest with no PV drivers.
4433		xirc2ps_cs=	[NET,PCMCIA]
4434				Format:
4435				<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
4437	______________________________________________________________________
4439	TODO:
4441		Add more DRM drivers.
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