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Based on kernel version 4.16.1. Page generated on 2018-04-09 11:52 EST.

1		acpi=		[HW,ACPI,X86,ARM64]
2				Advanced Configuration and Power Interface
3				Format: { force | on | off | strict | noirq | rsdt |
4					  copy_dsdt }
5				force -- enable ACPI if default was off
6				on -- enable ACPI but allow fallback to DT [arm64]
7				off -- disable ACPI if default was on
8				noirq -- do not use ACPI for IRQ routing
9				strict -- Be less tolerant of platforms that are not
10					strictly ACPI specification compliant.
11				rsdt -- prefer RSDT over (default) XSDT
12				copy_dsdt -- copy DSDT to memory
13				For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force"
14				are available
15	
16				See also Documentation/power/runtime_pm.txt, pci=noacpi
17	
18		acpi_apic_instance=	[ACPI, IOAPIC]
19				Format: <int>
20				2: use 2nd APIC table, if available
21				1,0: use 1st APIC table
22				default: 0
23	
24		acpi_backlight=	[HW,ACPI]
25				acpi_backlight=vendor
26				acpi_backlight=video
27				If set to vendor, prefer vendor specific driver
28				(e.g. thinkpad_acpi, sony_acpi, etc.) instead
29				of the ACPI video.ko driver.
30	
31		acpi_force_32bit_fadt_addr
32				force FADT to use 32 bit addresses rather than the
33				64 bit X_* addresses. Some firmware have broken 64
34				bit addresses for force ACPI ignore these and use
35				the older legacy 32 bit addresses.
36	
37		acpica_no_return_repair [HW, ACPI]
38				Disable AML predefined validation mechanism
39				This mechanism can repair the evaluation result to make
40				the return objects more ACPI specification compliant.
41				This option is useful for developers to identify the
42				root cause of an AML interpreter issue when the issue
43				has something to do with the repair mechanism.
44	
45		acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
46		acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
47				Format: <int>
48				CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
49				debug output.  Bits in debug_layer correspond to a
50				_COMPONENT in an ACPI source file, e.g.,
51				    #define _COMPONENT ACPI_PCI_COMPONENT
52				Bits in debug_level correspond to a level in
53				ACPI_DEBUG_PRINT statements, e.g.,
54				    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
55				The debug_level mask defaults to "info".  See
56				Documentation/acpi/debug.txt for more information about
57				debug layers and levels.
58	
59				Enable processor driver info messages:
60				    acpi.debug_layer=0x20000000
61				Enable PCI/PCI interrupt routing info messages:
62				    acpi.debug_layer=0x400000
63				Enable AML "Debug" output, i.e., stores to the Debug
64				object while interpreting AML:
65				    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
66				Enable all messages related to ACPI hardware:
67				    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
68	
69				Some values produce so much output that the system is
70				unusable.  The "log_buf_len" parameter may be useful
71				if you need to capture more output.
72	
73		acpi_enforce_resources=	[ACPI]
74				{ strict | lax | no }
75				Check for resource conflicts between native drivers
76				and ACPI OperationRegions (SystemIO and SystemMemory
77				only). IO ports and memory declared in ACPI might be
78				used by the ACPI subsystem in arbitrary AML code and
79				can interfere with legacy drivers.
80				strict (default): access to resources claimed by ACPI
81				is denied; legacy drivers trying to access reserved
82				resources will fail to bind to device using them.
83				lax: access to resources claimed by ACPI is allowed;
84				legacy drivers trying to access reserved resources
85				will bind successfully but a warning message is logged.
86				no: ACPI OperationRegions are not marked as reserved,
87				no further checks are performed.
88	
89		acpi_force_table_verification	[HW,ACPI]
90				Enable table checksum verification during early stage.
91				By default, this is disabled due to x86 early mapping
92				size limitation.
93	
94		acpi_irq_balance [HW,ACPI]
95				ACPI will balance active IRQs
96				default in APIC mode
97	
98		acpi_irq_nobalance [HW,ACPI]
99				ACPI will not move active IRQs (default)
100				default in PIC mode
101	
102		acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
103				Format: <irq>,<irq>...
104	
105		acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
106				use by PCI
107				Format: <irq>,<irq>...
108	
109		acpi_mask_gpe=  [HW,ACPI]
110				Due to the existence of _Lxx/_Exx, some GPEs triggered
111				by unsupported hardware/firmware features can result in
112	                        GPE floodings that cannot be automatically disabled by
113	                        the GPE dispatcher.
114				This facility can be used to prevent such uncontrolled
115				GPE floodings.
116				Format: <int>
117	
118		acpi_no_auto_serialize	[HW,ACPI]
119				Disable auto-serialization of AML methods
120				AML control methods that contain the opcodes to create
121				named objects will be marked as "Serialized" by the
122				auto-serialization feature.
123				This feature is enabled by default.
124				This option allows to turn off the feature.
125	
126		acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kdump
127				   kernels.
128	
129		acpi_no_static_ssdt	[HW,ACPI]
130				Disable installation of static SSDTs at early boot time
131				By default, SSDTs contained in the RSDT/XSDT will be
132				installed automatically and they will appear under
133				/sys/firmware/acpi/tables.
134				This option turns off this feature.
135				Note that specifying this option does not affect
136				dynamic table installation which will install SSDT
137				tables to /sys/firmware/acpi/tables/dynamic.
138	
139		acpi_rsdp=	[ACPI,EFI,KEXEC]
140				Pass the RSDP address to the kernel, mostly used
141				on machines running EFI runtime service to boot the
142				second kernel for kdump.
143	
144		acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
145				Format: To spoof as Windows 98: ="Microsoft Windows"
146	
147		acpi_rev_override [ACPI] Override the _REV object to return 5 (instead
148				of 2 which is mandated by ACPI 6) as the supported ACPI
149				specification revision (when using this switch, it may
150				be necessary to carry out a cold reboot _twice_ in a
151				row to make it take effect on the platform firmware).
152	
153		acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
154				acpi_osi="string1"	# add string1
155				acpi_osi="!string2"	# remove string2
156				acpi_osi=!*		# remove all strings
157				acpi_osi=!		# disable all built-in OS vendor
158							  strings
159				acpi_osi=!!		# enable all built-in OS vendor
160							  strings
161				acpi_osi=		# disable all strings
162	
163				'acpi_osi=!' can be used in combination with single or
164				multiple 'acpi_osi="string1"' to support specific OS
165				vendor string(s).  Note that such command can only
166				affect the default state of the OS vendor strings, thus
167				it cannot affect the default state of the feature group
168				strings and the current state of the OS vendor strings,
169				specifying it multiple times through kernel command line
170				is meaningless.  This command is useful when one do not
171				care about the state of the feature group strings which
172				should be controlled by the OSPM.
173				Examples:
174				  1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
175				     to 'acpi_osi="Windows 2000" acpi_osi=!', they all
176				     can make '_OSI("Windows 2000")' TRUE.
177	
178				'acpi_osi=' cannot be used in combination with other
179				'acpi_osi=' command lines, the _OSI method will not
180				exist in the ACPI namespace.  NOTE that such command can
181				only affect the _OSI support state, thus specifying it
182				multiple times through kernel command line is also
183				meaningless.
184				Examples:
185				  1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
186				     FALSE.
187	
188				'acpi_osi=!*' can be used in combination with single or
189				multiple 'acpi_osi="string1"' to support specific
190				string(s).  Note that such command can affect the
191				current state of both the OS vendor strings and the
192				feature group strings, thus specifying it multiple times
193				through kernel command line is meaningful.  But it may
194				still not able to affect the final state of a string if
195				there are quirks related to this string.  This command
196				is useful when one want to control the state of the
197				feature group strings to debug BIOS issues related to
198				the OSPM features.
199				Examples:
200				  1. 'acpi_osi="Module Device" acpi_osi=!*' can make
201				     '_OSI("Module Device")' FALSE.
202				  2. 'acpi_osi=!* acpi_osi="Module Device"' can make
203				     '_OSI("Module Device")' TRUE.
204				  3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
205				     equivalent to
206				     'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
207				     and
208				     'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
209				     they all will make '_OSI("Windows 2000")' TRUE.
210	
211		acpi_pm_good	[X86]
212				Override the pmtimer bug detection: force the kernel
213				to assume that this machine's pmtimer latches its value
214				and always returns good values.
215	
216		acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
217				Format: { level | edge | high | low }
218	
219		acpi_skip_timer_override [HW,ACPI]
220				Recognize and ignore IRQ0/pin2 Interrupt Override.
221				For broken nForce2 BIOS resulting in XT-PIC timer.
222	
223		acpi_sleep=	[HW,ACPI] Sleep options
224				Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
225					  old_ordering, nonvs, sci_force_enable, nobl }
226				See Documentation/power/video.txt for information on
227				s3_bios and s3_mode.
228				s3_beep is for debugging; it makes the PC's speaker beep
229				as soon as the kernel's real-mode entry point is called.
230				s4_nohwsig prevents ACPI hardware signature from being
231				used during resume from hibernation.
232				old_ordering causes the ACPI 1.0 ordering of the _PTS
233				control method, with respect to putting devices into
234				low power states, to be enforced (the ACPI 2.0 ordering
235				of _PTS is used by default).
236				nonvs prevents the kernel from saving/restoring the
237				ACPI NVS memory during suspend/hibernation and resume.
238				sci_force_enable causes the kernel to set SCI_EN directly
239				on resume from S1/S3 (which is against the ACPI spec,
240				but some broken systems don't work without it).
241				nobl causes the internal blacklist of systems known to
242				behave incorrectly in some ways with respect to system
243				suspend and resume to be ignored (use wisely).
244	
245		acpi_use_timer_override [HW,ACPI]
246				Use timer override. For some broken Nvidia NF5 boards
247				that require a timer override, but don't have HPET
248	
249		add_efi_memmap	[EFI; X86] Include EFI memory map in
250				kernel's map of available physical RAM.
251	
252		agp=		[AGP]
253				{ off | try_unsupported }
254				off: disable AGP support
255				try_unsupported: try to drive unsupported chipsets
256					(may crash computer or cause data corruption)
257	
258		ALSA		[HW,ALSA]
259				See Documentation/sound/alsa/alsa-parameters.txt
260	
261		alignment=	[KNL,ARM]
262				Allow the default userspace alignment fault handler
263				behaviour to be specified.  Bit 0 enables warnings,
264				bit 1 enables fixups, and bit 2 sends a segfault.
265	
266		align_va_addr=	[X86-64]
267				Align virtual addresses by clearing slice [14:12] when
268				allocating a VMA at process creation time. This option
269				gives you up to 3% performance improvement on AMD F15h
270				machines (where it is enabled by default) for a
271				CPU-intensive style benchmark, and it can vary highly in
272				a microbenchmark depending on workload and compiler.
273	
274				32: only for 32-bit processes
275				64: only for 64-bit processes
276				on: enable for both 32- and 64-bit processes
277				off: disable for both 32- and 64-bit processes
278	
279		alloc_snapshot	[FTRACE]
280				Allocate the ftrace snapshot buffer on boot up when the
281				main buffer is allocated. This is handy if debugging
282				and you need to use tracing_snapshot() on boot up, and
283				do not want to use tracing_snapshot_alloc() as it needs
284				to be done where GFP_KERNEL allocations are allowed.
285	
286		amd_iommu=	[HW,X86-64]
287				Pass parameters to the AMD IOMMU driver in the system.
288				Possible values are:
289				fullflush - enable flushing of IO/TLB entries when
290					    they are unmapped. Otherwise they are
291					    flushed before they will be reused, which
292					    is a lot of faster
293				off	  - do not initialize any AMD IOMMU found in
294					    the system
295				force_isolation - Force device isolation for all
296						  devices. The IOMMU driver is not
297						  allowed anymore to lift isolation
298						  requirements as needed. This option
299						  does not override iommu=pt
300	
301		amd_iommu_dump=	[HW,X86-64]
302				Enable AMD IOMMU driver option to dump the ACPI table
303				for AMD IOMMU. With this option enabled, AMD IOMMU
304				driver will print ACPI tables for AMD IOMMU during
305				IOMMU initialization.
306	
307		amd_iommu_intr=	[HW,X86-64]
308				Specifies one of the following AMD IOMMU interrupt
309				remapping modes:
310				legacy     - Use legacy interrupt remapping mode.
311				vapic      - Use virtual APIC mode, which allows IOMMU
312				             to inject interrupts directly into guest.
313				             This mode requires kvm-amd.avic=1.
314				             (Default when IOMMU HW support is present.)
315	
316		amijoy.map=	[HW,JOY] Amiga joystick support
317				Map of devices attached to JOY0DAT and JOY1DAT
318				Format: <a>,<b>
319				See also Documentation/input/joydev/joystick.rst
320	
321		analog.map=	[HW,JOY] Analog joystick and gamepad support
322				Specifies type or capabilities of an analog joystick
323				connected to one of 16 gameports
324				Format: <type1>,<type2>,..<type16>
325	
326		apc=		[HW,SPARC]
327				Power management functions (SPARCstation-4/5 + deriv.)
328				Format: noidle
329				Disable APC CPU standby support. SPARCstation-Fox does
330				not play well with APC CPU idle - disable it if you have
331				APC and your system crashes randomly.
332	
333		apic=		[APIC,X86] Advanced Programmable Interrupt Controller
334				Change the output verbosity whilst booting
335				Format: { quiet (default) | verbose | debug }
336				Change the amount of debugging information output
337				when initialising the APIC and IO-APIC components.
338				For X86-32, this can also be used to specify an APIC
339				driver name.
340				Format: apic=driver_name
341				Examples: apic=bigsmp
342	
343		apic_extnmi=	[APIC,X86] External NMI delivery setting
344				Format: { bsp (default) | all | none }
345				bsp:  External NMI is delivered only to CPU 0
346				all:  External NMIs are broadcast to all CPUs as a
347				      backup of CPU 0
348				none: External NMI is masked for all CPUs. This is
349				      useful so that a dump capture kernel won't be
350				      shot down by NMI
351	
352		autoconf=	[IPV6]
353				See Documentation/networking/ipv6.txt.
354	
355		show_lapic=	[APIC,X86] Advanced Programmable Interrupt Controller
356				Limit apic dumping. The parameter defines the maximal
357				number of local apics being dumped. Also it is possible
358				to set it to "all" by meaning -- no limit here.
359				Format: { 1 (default) | 2 | ... | all }.
360				The parameter valid if only apic=debug or
361				apic=verbose is specified.
362				Example: apic=debug show_lapic=all
363	
364		apm=		[APM] Advanced Power Management
365				See header of arch/x86/kernel/apm_32.c.
366	
367		arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
368				Format: <io>,<irq>,<nodeID>
369	
370		ataflop=	[HW,M68k]
371	
372		atarimouse=	[HW,MOUSE] Atari Mouse
373	
374		atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
375				EzKey and similar keyboards
376	
377		atkbd.reset=	[HW] Reset keyboard during initialization
378	
379		atkbd.set=	[HW] Select keyboard code set
380				Format: <int> (2 = AT (default), 3 = PS/2)
381	
382		atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
383				keyboards
384	
385		atkbd.softraw=	[HW] Choose between synthetic and real raw mode
386				Format: <bool> (0 = real, 1 = synthetic (default))
387	
388		atkbd.softrepeat= [HW]
389				Use software keyboard repeat
390	
391		audit=		[KNL] Enable the audit sub-system
392				Format: { "0" | "1" } (0 = disabled, 1 = enabled)
393				0 - kernel audit is disabled and can not be enabled
394				    until the next reboot
395				unset - kernel audit is initialized but disabled and
396				    will be fully enabled by the userspace auditd.
397				1 - kernel audit is initialized and partially enabled,
398				    storing at most audit_backlog_limit messages in
399				    RAM until it is fully enabled by the userspace
400				    auditd.
401				Default: unset
402	
403		audit_backlog_limit= [KNL] Set the audit queue size limit.
404				Format: <int> (must be >=0)
405				Default: 64
406	
407		bau=		[X86_UV] Enable the BAU on SGI UV.  The default
408				behavior is to disable the BAU (i.e. bau=0).
409				Format: { "0" | "1" }
410				0 - Disable the BAU.
411				1 - Enable the BAU.
412				unset - Disable the BAU.
413	
414		baycom_epp=	[HW,AX25]
415				Format: <io>,<mode>
416	
417		baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
418				Format: <io>,<mode>
419				See header of drivers/net/hamradio/baycom_par.c.
420	
421		baycom_ser_fdx=	[HW,AX25]
422				BayCom Serial Port AX.25 Modem (Full Duplex Mode)
423				Format: <io>,<irq>,<mode>[,<baud>]
424				See header of drivers/net/hamradio/baycom_ser_fdx.c.
425	
426		baycom_ser_hdx=	[HW,AX25]
427				BayCom Serial Port AX.25 Modem (Half Duplex Mode)
428				Format: <io>,<irq>,<mode>
429				See header of drivers/net/hamradio/baycom_ser_hdx.c.
430	
431		blkdevparts=	Manual partition parsing of block device(s) for
432				embedded devices based on command line input.
433				See Documentation/block/cmdline-partition.txt
434	
435		boot_delay=	Milliseconds to delay each printk during boot.
436				Values larger than 10 seconds (10000) are changed to
437				no delay (0).
438				Format: integer
439	
440		bootmem_debug	[KNL] Enable bootmem allocator debug messages.
441	
442		bert_disable	[ACPI]
443				Disable BERT OS support on buggy BIOSes.
444	
445		bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
446		bttv.radio=	Most important insmod options are available as
447				kernel args too.
448		bttv.pll=	See Documentation/media/v4l-drivers/bttv.rst
449		bttv.tuner=
450	
451		bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
452				firmware feature for flushing multiple hpte entries
453				at a time.
454	
455		c101=		[NET] Moxa C101 synchronous serial card
456	
457		cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
458				Sometimes CPU hardware bugs make them report the cache
459				size incorrectly. The kernel will attempt work arounds
460				to fix known problems, but for some CPUs it is not
461				possible to determine what the correct size should be.
462				This option provides an override for these situations.
463	
464		ca_keys=	[KEYS] This parameter identifies a specific key(s) on
465				the system trusted keyring to be used for certificate
466				trust validation.
467				format: { id:<keyid> | builtin }
468	
469		cca=		[MIPS] Override the kernel pages' cache coherency
470				algorithm.  Accepted values range from 0 to 7
471				inclusive. See arch/mips/include/asm/pgtable-bits.h
472				for platform specific values (SB1, Loongson3 and
473				others).
474	
475		ccw_timeout_log [S390]
476				See Documentation/s390/CommonIO for details.
477	
478		cgroup_disable= [KNL] Disable a particular controller
479				Format: {name of the controller(s) to disable}
480				The effects of cgroup_disable=foo are:
481				- foo isn't auto-mounted if you mount all cgroups in
482				  a single hierarchy
483				- foo isn't visible as an individually mountable
484				  subsystem
485				{Currently only "memory" controller deal with this and
486				cut the overhead, others just disable the usage. So
487				only cgroup_disable=memory is actually worthy}
488	
489		cgroup_no_v1=	[KNL] Disable one, multiple, all cgroup controllers in v1
490				Format: { controller[,controller...] | "all" }
491				Like cgroup_disable, but only applies to cgroup v1;
492				the blacklisted controllers remain available in cgroup2.
493	
494		cgroup.memory=	[KNL] Pass options to the cgroup memory controller.
495				Format: <string>
496				nosocket -- Disable socket memory accounting.
497				nokmem -- Disable kernel memory accounting.
498	
499		checkreqprot	[SELINUX] Set initial checkreqprot flag value.
500				Format: { "0" | "1" }
501				See security/selinux/Kconfig help text.
502				0 -- check protection applied by kernel (includes
503					any implied execute protection).
504				1 -- check protection requested by application.
505				Default value is set via a kernel config option.
506				Value can be changed at runtime via
507					/selinux/checkreqprot.
508	
509		cio_ignore=	[S390]
510				See Documentation/s390/CommonIO for details.
511		clk_ignore_unused
512				[CLK]
513				Prevents the clock framework from automatically gating
514				clocks that have not been explicitly enabled by a Linux
515				device driver but are enabled in hardware at reset or
516				by the bootloader/firmware. Note that this does not
517				force such clocks to be always-on nor does it reserve
518				those clocks in any way. This parameter is useful for
519				debug and development, but should not be needed on a
520				platform with proper driver support.  For more
521				information, see Documentation/clk.txt.
522	
523		clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
524				[Deprecated]
525				Forces specified clocksource (if available) to be used
526				when calculating gettimeofday(). If specified
527				clocksource is not available, it defaults to PIT.
528				Format: { pit | tsc | cyclone | pmtmr }
529	
530		clocksource=	Override the default clocksource
531				Format: <string>
532				Override the default clocksource and use the clocksource
533				with the name specified.
534				Some clocksource names to choose from, depending on
535				the platform:
536				[all] jiffies (this is the base, fallback clocksource)
537				[ACPI] acpi_pm
538				[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
539					pxa_timer,timer3,32k_counter,timer0_1
540				[X86-32] pit,hpet,tsc;
541					scx200_hrt on Geode; cyclone on IBM x440
542				[MIPS] MIPS
543				[PARISC] cr16
544				[S390] tod
545				[SH] SuperH
546				[SPARC64] tick
547				[X86-64] hpet,tsc
548	
549		clocksource.arm_arch_timer.evtstrm=
550				[ARM,ARM64]
551				Format: <bool>
552				Enable/disable the eventstream feature of the ARM
553				architected timer so that code using WFE-based polling
554				loops can be debugged more effectively on production
555				systems.
556	
557		clearcpuid=BITNUM [X86]
558				Disable CPUID feature X for the kernel. See
559				arch/x86/include/asm/cpufeatures.h for the valid bit
560				numbers. Note the Linux specific bits are not necessarily
561				stable over kernel options, but the vendor specific
562				ones should be.
563				Also note that user programs calling CPUID directly
564				or using the feature without checking anything
565				will still see it. This just prevents it from
566				being used by the kernel or shown in /proc/cpuinfo.
567				Also note the kernel might malfunction if you disable
568				some critical bits.
569	
570		cma=nn[MG]@[start[MG][-end[MG]]]
571				[ARM,X86,KNL]
572				Sets the size of kernel global memory area for
573				contiguous memory allocations and optionally the
574				placement constraint by the physical address range of
575				memory allocations. A value of 0 disables CMA
576				altogether. For more information, see
577				include/linux/dma-contiguous.h
578	
579		cmo_free_hint=	[PPC] Format: { yes | no }
580				Specify whether pages are marked as being inactive
581				when they are freed.  This is used in CMO environments
582				to determine OS memory pressure for page stealing by
583				a hypervisor.
584				Default: yes
585	
586		coherent_pool=nn[KMG]	[ARM,KNL]
587				Sets the size of memory pool for coherent, atomic dma
588				allocations, by default set to 256K.
589	
590		code_bytes	[X86] How many bytes of object code to print
591				in an oops report.
592				Range: 0 - 8192
593				Default: 64
594	
595		com20020=	[HW,NET] ARCnet - COM20020 chipset
596				Format:
597				<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
598	
599		com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
600				Format: <io>[,<irq>]
601	
602		com90xx=	[HW,NET]
603				ARCnet - COM90xx chipset (memory-mapped buffers)
604				Format: <io>[,<irq>[,<memstart>]]
605	
606		condev=		[HW,S390] console device
607		conmode=
608	
609		console=	[KNL] Output console device and options.
610	
611			tty<n>	Use the virtual console device <n>.
612	
613			ttyS<n>[,options]
614			ttyUSB0[,options]
615				Use the specified serial port.  The options are of
616				the form "bbbbpnf", where "bbbb" is the baud rate,
617				"p" is parity ("n", "o", or "e"), "n" is number of
618				bits, and "f" is flow control ("r" for RTS or
619				omit it).  Default is "9600n8".
620	
621				See Documentation/admin-guide/serial-console.rst for more
622				information.  See
623				Documentation/networking/netconsole.txt for an
624				alternative.
625	
626			uart[8250],io,<addr>[,options]
627			uart[8250],mmio,<addr>[,options]
628			uart[8250],mmio16,<addr>[,options]
629			uart[8250],mmio32,<addr>[,options]
630			uart[8250],0x<addr>[,options]
631				Start an early, polled-mode console on the 8250/16550
632				UART at the specified I/O port or MMIO address,
633				switching to the matching ttyS device later.
634				MMIO inter-register address stride is either 8-bit
635				(mmio), 16-bit (mmio16), or 32-bit (mmio32).
636				If none of [io|mmio|mmio16|mmio32], <addr> is assumed
637				to be equivalent to 'mmio'. 'options' are specified in
638				the same format described for ttyS above; if unspecified,
639				the h/w is not re-initialized.
640	
641			hvc<n>	Use the hypervisor console device <n>. This is for
642				both Xen and PowerPC hypervisors.
643	
644	                If the device connected to the port is not a TTY but a braille
645	                device, prepend "brl," before the device type, for instance
646				console=brl,ttyS0
647			For now, only VisioBraille is supported.
648	
649		console_msg_format=
650				[KNL] Change console messages format
651			default
652				By default we print messages on consoles in
653				"[time stamp] text\n" format (time stamp may not be
654				printed, depending on CONFIG_PRINTK_TIME or
655				`printk_time' param).
656			syslog
657				Switch to syslog format: "<%u>[time stamp] text\n"
658				IOW, each message will have a facility and loglevel
659				prefix. The format is similar to one used by syslog()
660				syscall, or to executing "dmesg -S --raw" or to reading
661				from /proc/kmsg.
662	
663		consoleblank=	[KNL] The console blank (screen saver) timeout in
664				seconds. A value of 0 disables the blank timer.
665	                       Defaults to 0.
666	
667		coredump_filter=
668				[KNL] Change the default value for
669				/proc/<pid>/coredump_filter.
670				See also Documentation/filesystems/proc.txt.
671	
672		coresight_cpu_debug.enable
673				[ARM,ARM64]
674				Format: <bool>
675				Enable/disable the CPU sampling based debugging.
676				0: default value, disable debugging
677				1: enable debugging at boot time
678	
679		cpuidle.off=1	[CPU_IDLE]
680				disable the cpuidle sub-system
681	
682		cpufreq.off=1	[CPU_FREQ]
683				disable the cpufreq sub-system
684	
685		cpu_init_udelay=N
686				[X86] Delay for N microsec between assert and de-assert
687				of APIC INIT to start processors.  This delay occurs
688				on every CPU online, such as boot, and resume from suspend.
689				Default: 10000
690	
691		cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
692				Format:
693				<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
694	
695		crashkernel=size[KMG][@offset[KMG]]
696				[KNL] Using kexec, Linux can switch to a 'crash kernel'
697				upon panic. This parameter reserves the physical
698				memory region [offset, offset + size] for that kernel
699				image. If '@offset' is omitted, then a suitable offset
700				is selected automatically. Check
701				Documentation/kdump/kdump.txt for further details.
702	
703		crashkernel=range1:size1[,range2:size2,...][@offset]
704				[KNL] Same as above, but depends on the memory
705				in the running system. The syntax of range is
706				start-[end] where start and end are both
707				a memory unit (amount[KMG]). See also
708				Documentation/kdump/kdump.txt for an example.
709	
710		crashkernel=size[KMG],high
711				[KNL, x86_64] range could be above 4G. Allow kernel
712				to allocate physical memory region from top, so could
713				be above 4G if system have more than 4G ram installed.
714				Otherwise memory region will be allocated below 4G, if
715				available.
716				It will be ignored if crashkernel=X is specified.
717		crashkernel=size[KMG],low
718				[KNL, x86_64] range under 4G. When crashkernel=X,high
719				is passed, kernel could allocate physical memory region
720				above 4G, that cause second kernel crash on system
721				that require some amount of low memory, e.g. swiotlb
722				requires at least 64M+32K low memory, also enough extra
723				low memory is needed to make sure DMA buffers for 32-bit
724				devices won't run out. Kernel would try to allocate at
725				at least 256M below 4G automatically.
726				This one let user to specify own low range under 4G
727				for second kernel instead.
728				0: to disable low allocation.
729				It will be ignored when crashkernel=X,high is not used
730				or memory reserved is below 4G.
731	
732		cryptomgr.notests
733	                        [KNL] Disable crypto self-tests
734	
735		cs89x0_dma=	[HW,NET]
736				Format: <dma>
737	
738		cs89x0_media=	[HW,NET]
739				Format: { rj45 | aui | bnc }
740	
741		dasd=		[HW,NET]
742				See header of drivers/s390/block/dasd_devmap.c.
743	
744		db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
745				(one device per port)
746				Format: <port#>,<type>
747				See also Documentation/input/devices/joystick-parport.rst
748	
749		ddebug_query=   [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
750				time. See
751				Documentation/admin-guide/dynamic-debug-howto.rst for
752				details.  Deprecated, see dyndbg.
753	
754		debug		[KNL] Enable kernel debugging (events log level).
755	
756		debug_locks_verbose=
757				[KNL] verbose self-tests
758				Format=<0|1>
759				Print debugging info while doing the locking API
760				self-tests.
761				We default to 0 (no extra messages), setting it to
762				1 will print _a lot_ more information - normally
763				only useful to kernel developers.
764	
765		debug_objects	[KNL] Enable object debugging
766	
767		no_debug_objects
768				[KNL] Disable object debugging
769	
770		debug_guardpage_minorder=
771				[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
772				parameter allows control of the order of pages that will
773				be intentionally kept free (and hence protected) by the
774				buddy allocator. Bigger value increase the probability
775				of catching random memory corruption, but reduce the
776				amount of memory for normal system use. The maximum
777				possible value is MAX_ORDER/2.  Setting this parameter
778				to 1 or 2 should be enough to identify most random
779				memory corruption problems caused by bugs in kernel or
780				driver code when a CPU writes to (or reads from) a
781				random memory location. Note that there exists a class
782				of memory corruptions problems caused by buggy H/W or
783				F/W or by drivers badly programing DMA (basically when
784				memory is written at bus level and the CPU MMU is
785				bypassed) which are not detectable by
786				CONFIG_DEBUG_PAGEALLOC, hence this option will not help
787				tracking down these problems.
788	
789		debug_pagealloc=
790				[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
791				parameter enables the feature at boot time. In
792				default, it is disabled. We can avoid allocating huge
793				chunk of memory for debug pagealloc if we don't enable
794				it at boot time and the system will work mostly same
795				with the kernel built without CONFIG_DEBUG_PAGEALLOC.
796				on: enable the feature
797	
798		debugpat	[X86] Enable PAT debugging
799	
800		decnet.addr=	[HW,NET]
801				Format: <area>[,<node>]
802				See also Documentation/networking/decnet.txt.
803	
804		default_hugepagesz=
805				[same as hugepagesz=] The size of the default
806				HugeTLB page size. This is the size represented by
807				the legacy /proc/ hugepages APIs, used for SHM, and
808				default size when mounting hugetlbfs filesystems.
809				Defaults to the default architecture's huge page size
810				if not specified.
811	
812		dhash_entries=	[KNL]
813				Set number of hash buckets for dentry cache.
814	
815		disable_1tb_segments [PPC]
816				Disables the use of 1TB hash page table segments. This
817				causes the kernel to fall back to 256MB segments which
818				can be useful when debugging issues that require an SLB
819				miss to occur.
820	
821		disable=	[IPV6]
822				See Documentation/networking/ipv6.txt.
823	
824		disable_radix	[PPC]
825				Disable RADIX MMU mode on POWER9
826	
827		disable_cpu_apicid= [X86,APIC,SMP]
828				Format: <int>
829				The number of initial APIC ID for the
830				corresponding CPU to be disabled at boot,
831				mostly used for the kdump 2nd kernel to
832				disable BSP to wake up multiple CPUs without
833				causing system reset or hang due to sending
834				INIT from AP to BSP.
835	
836		disable_ddw     [PPC/PSERIES]
837				Disable Dynamic DMA Window support. Use this if
838				to workaround buggy firmware.
839	
840		disable_ipv6=	[IPV6]
841				See Documentation/networking/ipv6.txt.
842	
843		disable_mtrr_cleanup [X86]
844				The kernel tries to adjust MTRR layout from continuous
845				to discrete, to make X server driver able to add WB
846				entry later. This parameter disables that.
847	
848		disable_mtrr_trim [X86, Intel and AMD only]
849				By default the kernel will trim any uncacheable
850				memory out of your available memory pool based on
851				MTRR settings.  This parameter disables that behavior,
852				possibly causing your machine to run very slowly.
853	
854		disable_timer_pin_1 [X86]
855				Disable PIN 1 of APIC timer
856				Can be useful to work around chipset bugs.
857	
858		dis_ucode_ldr	[X86] Disable the microcode loader.
859	
860		dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
861				this option disables the debugging code at boot.
862	
863		dma_debug_entries=<number>
864				This option allows to tune the number of preallocated
865				entries for DMA-API debugging code. One entry is
866				required per DMA-API allocation. Use this if the
867				DMA-API debugging code disables itself because the
868				architectural default is too low.
869	
870		dma_debug_driver=<driver_name>
871				With this option the DMA-API debugging driver
872				filter feature can be enabled at boot time. Just
873				pass the driver to filter for as the parameter.
874				The filter can be disabled or changed to another
875				driver later using sysfs.
876	
877		drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
878				Broken monitors, graphic adapters, KVMs and EDIDless
879				panels may send no or incorrect EDID data sets.
880				This parameter allows to specify an EDID data sets
881				in the /lib/firmware directory that are used instead.
882				Generic built-in EDID data sets are used, if one of
883				edid/1024x768.bin, edid/1280x1024.bin,
884				edid/1680x1050.bin, or edid/1920x1080.bin is given
885				and no file with the same name exists. Details and
886				instructions how to build your own EDID data are
887				available in Documentation/EDID/HOWTO.txt. An EDID
888				data set will only be used for a particular connector,
889				if its name and a colon are prepended to the EDID
890				name. Each connector may use a unique EDID data
891				set by separating the files with a comma.  An EDID
892				data set with no connector name will be used for
893				any connectors not explicitly specified.
894	
895		dscc4.setup=	[NET]
896	
897		dt_cpu_ftrs=	[PPC]
898				Format: {"off" | "known"}
899				Control how the dt_cpu_ftrs device-tree binding is
900				used for CPU feature discovery and setup (if it
901				exists).
902				off: Do not use it, fall back to legacy cpu table.
903				known: Do not pass through unknown features to guests
904				or userspace, only those that the kernel is aware of.
905	
906		dump_apple_properties	[X86]
907				Dump name and content of EFI device properties on
908				x86 Macs.  Useful for driver authors to determine
909				what data is available or for reverse-engineering.
910	
911		dyndbg[="val"]		[KNL,DYNAMIC_DEBUG]
912		module.dyndbg[="val"]
913				Enable debug messages at boot time.  See
914				Documentation/admin-guide/dynamic-debug-howto.rst
915				for details.
916	
917		nompx		[X86] Disables Intel Memory Protection Extensions.
918				See Documentation/x86/intel_mpx.txt for more
919				information about the feature.
920	
921		nopku		[X86] Disable Memory Protection Keys CPU feature found
922				in some Intel CPUs.
923	
924		module.async_probe [KNL]
925				Enable asynchronous probe on this module.
926	
927		early_ioremap_debug [KNL]
928				Enable debug messages in early_ioremap support. This
929				is useful for tracking down temporary early mappings
930				which are not unmapped.
931	
932		earlycon=	[KNL] Output early console device and options.
933	
934				[ARM64] The early console is determined by the
935				stdout-path property in device tree's chosen node,
936				or determined by the ACPI SPCR table.
937	
938				[X86] When used with no options the early console is
939				determined by the ACPI SPCR table.
940	
941			cdns,<addr>[,options]
942				Start an early, polled-mode console on a Cadence
943				(xuartps) serial port at the specified address. Only
944				supported option is baud rate. If baud rate is not
945				specified, the serial port must already be setup and
946				configured.
947	
948			uart[8250],io,<addr>[,options]
949			uart[8250],mmio,<addr>[,options]
950			uart[8250],mmio32,<addr>[,options]
951			uart[8250],mmio32be,<addr>[,options]
952			uart[8250],0x<addr>[,options]
953				Start an early, polled-mode console on the 8250/16550
954				UART at the specified I/O port or MMIO address.
955				MMIO inter-register address stride is either 8-bit
956				(mmio) or 32-bit (mmio32 or mmio32be).
957				If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
958				to be equivalent to 'mmio'. 'options' are specified
959				in the same format described for "console=ttyS<n>"; if
960				unspecified, the h/w is not initialized.
961	
962			pl011,<addr>
963			pl011,mmio32,<addr>
964				Start an early, polled-mode console on a pl011 serial
965				port at the specified address. The pl011 serial port
966				must already be setup and configured. Options are not
967				yet supported.  If 'mmio32' is specified, then only
968				the driver will use only 32-bit accessors to read/write
969				the device registers.
970	
971			meson,<addr>
972				Start an early, polled-mode console on a meson serial
973				port at the specified address. The serial port must
974				already be setup and configured. Options are not yet
975				supported.
976	
977			msm_serial,<addr>
978				Start an early, polled-mode console on an msm serial
979				port at the specified address. The serial port
980				must already be setup and configured. Options are not
981				yet supported.
982	
983			msm_serial_dm,<addr>
984				Start an early, polled-mode console on an msm serial
985				dm port at the specified address. The serial port
986				must already be setup and configured. Options are not
987				yet supported.
988	
989			owl,<addr>
990				Start an early, polled-mode console on a serial port
991				of an Actions Semi SoC, such as S500 or S900, at the
992				specified address. The serial port must already be
993				setup and configured. Options are not yet supported.
994	
995			smh	Use ARM semihosting calls for early console.
996	
997			s3c2410,<addr>
998			s3c2412,<addr>
999			s3c2440,<addr>
1000			s3c6400,<addr>
1001			s5pv210,<addr>
1002			exynos4210,<addr>
1003				Use early console provided by serial driver available
1004				on Samsung SoCs, requires selecting proper type and
1005				a correct base address of the selected UART port. The
1006				serial port must already be setup and configured.
1007				Options are not yet supported.
1008	
1009			lantiq,<addr>
1010				Start an early, polled-mode console on a lantiq serial
1011				(lqasc) port at the specified address. The serial port
1012				must already be setup and configured. Options are not
1013				yet supported.
1014	
1015			lpuart,<addr>
1016			lpuart32,<addr>
1017				Use early console provided by Freescale LP UART driver
1018				found on Freescale Vybrid and QorIQ LS1021A processors.
1019				A valid base address must be provided, and the serial
1020				port must already be setup and configured.
1021	
1022			ar3700_uart,<addr>
1023				Start an early, polled-mode console on the
1024				Armada 3700 serial port at the specified
1025				address. The serial port must already be setup
1026				and configured. Options are not yet supported.
1027	
1028		earlyprintk=	[X86,SH,BLACKFIN,ARM,M68k,S390]
1029				earlyprintk=vga
1030				earlyprintk=efi
1031				earlyprintk=sclp
1032				earlyprintk=xen
1033				earlyprintk=serial[,ttySn[,baudrate]]
1034				earlyprintk=serial[,0x...[,baudrate]]
1035				earlyprintk=ttySn[,baudrate]
1036				earlyprintk=dbgp[debugController#]
1037				earlyprintk=pciserial,bus:device.function[,baudrate]
1038				earlyprintk=xdbc[xhciController#]
1039	
1040				earlyprintk is useful when the kernel crashes before
1041				the normal console is initialized. It is not enabled by
1042				default because it has some cosmetic problems.
1043	
1044				Append ",keep" to not disable it when the real console
1045				takes over.
1046	
1047				Only one of vga, efi, serial, or usb debug port can
1048				be used at a time.
1049	
1050				Currently only ttyS0 and ttyS1 may be specified by
1051				name.  Other I/O ports may be explicitly specified
1052				on some architectures (x86 and arm at least) by
1053				replacing ttySn with an I/O port address, like this:
1054					earlyprintk=serial,0x1008,115200
1055				You can find the port for a given device in
1056				/proc/tty/driver/serial:
1057					2: uart:ST16650V2 port:00001008 irq:18 ...
1058	
1059				Interaction with the standard serial driver is not
1060				very good.
1061	
1062				The VGA and EFI output is eventually overwritten by
1063				the real console.
1064	
1065				The xen output can only be used by Xen PV guests.
1066	
1067				The sclp output can only be used on s390.
1068	
1069		edac_report=	[HW,EDAC] Control how to report EDAC event
1070				Format: {"on" | "off" | "force"}
1071				on: enable EDAC to report H/W event. May be overridden
1072				by other higher priority error reporting module.
1073				off: disable H/W event reporting through EDAC.
1074				force: enforce the use of EDAC to report H/W event.
1075				default: on.
1076	
1077		ekgdboc=	[X86,KGDB] Allow early kernel console debugging
1078				ekgdboc=kbd
1079	
1080				This is designed to be used in conjunction with
1081				the boot argument: earlyprintk=vga
1082	
1083		edd=		[EDD]
1084				Format: {"off" | "on" | "skip[mbr]"}
1085	
1086		efi=		[EFI]
1087				Format: { "old_map", "nochunk", "noruntime", "debug" }
1088				old_map [X86-64]: switch to the old ioremap-based EFI
1089				runtime services mapping. 32-bit still uses this one by
1090				default.
1091				nochunk: disable reading files in "chunks" in the EFI
1092				boot stub, as chunking can cause problems with some
1093				firmware implementations.
1094				noruntime : disable EFI runtime services support
1095				debug: enable misc debug output
1096	
1097		efi_no_storage_paranoia [EFI; X86]
1098				Using this parameter you can use more than 50% of
1099				your efi variable storage. Use this parameter only if
1100				you are really sure that your UEFI does sane gc and
1101				fulfills the spec otherwise your board may brick.
1102	
1103		efi_fake_mem=	nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86]
1104				Add arbitrary attribute to specific memory range by
1105				updating original EFI memory map.
1106				Region of memory which aa attribute is added to is
1107				from ss to ss+nn.
1108				If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
1109				is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
1110				attribute is added to range 0x100000000-0x180000000 and
1111				0x10a0000000-0x1120000000.
1112	
1113				Using this parameter you can do debugging of EFI memmap
1114				related feature. For example, you can do debugging of
1115				Address Range Mirroring feature even if your box
1116				doesn't support it.
1117	
1118		efivar_ssdt=	[EFI; X86] Name of an EFI variable that contains an SSDT
1119				that is to be dynamically loaded by Linux. If there are
1120				multiple variables with the same name but with different
1121				vendor GUIDs, all of them will be loaded. See
1122				Documentation/acpi/ssdt-overlays.txt for details.
1123	
1124	
1125		eisa_irq_edge=	[PARISC,HW]
1126				See header of drivers/parisc/eisa.c.
1127	
1128		elanfreq=	[X86-32]
1129				See comment before function elanfreq_setup() in
1130				arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1131	
1132		elevator=	[IOSCHED]
1133				Format: {"cfq" | "deadline" | "noop"}
1134				See Documentation/block/cfq-iosched.txt and
1135				Documentation/block/deadline-iosched.txt for details.
1136	
1137		elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
1138				Specifies physical address of start of kernel core
1139				image elf header and optionally the size. Generally
1140				kexec loader will pass this option to capture kernel.
1141				See Documentation/kdump/kdump.txt for details.
1142	
1143		enable_mtrr_cleanup [X86]
1144				The kernel tries to adjust MTRR layout from continuous
1145				to discrete, to make X server driver able to add WB
1146				entry later. This parameter enables that.
1147	
1148		enable_timer_pin_1 [X86]
1149				Enable PIN 1 of APIC timer
1150				Can be useful to work around chipset bugs
1151				(in particular on some ATI chipsets).
1152				The kernel tries to set a reasonable default.
1153	
1154		enforcing	[SELINUX] Set initial enforcing status.
1155				Format: {"0" | "1"}
1156				See security/selinux/Kconfig help text.
1157				0 -- permissive (log only, no denials).
1158				1 -- enforcing (deny and log).
1159				Default value is 0.
1160				Value can be changed at runtime via /selinux/enforce.
1161	
1162		erst_disable	[ACPI]
1163				Disable Error Record Serialization Table (ERST)
1164				support.
1165	
1166		ether=		[HW,NET] Ethernet cards parameters
1167				This option is obsoleted by the "netdev=" option, which
1168				has equivalent usage. See its documentation for details.
1169	
1170		evm=		[EVM]
1171				Format: { "fix" }
1172				Permit 'security.evm' to be updated regardless of
1173				current integrity status.
1174	
1175		failslab=
1176		fail_page_alloc=
1177		fail_make_request=[KNL]
1178				General fault injection mechanism.
1179				Format: <interval>,<probability>,<space>,<times>
1180				See also Documentation/fault-injection/.
1181	
1182		floppy=		[HW]
1183				See Documentation/blockdev/floppy.txt.
1184	
1185		force_pal_cache_flush
1186				[IA-64] Avoid check_sal_cache_flush which may hang on
1187				buggy SAL_CACHE_FLUSH implementations. Using this
1188				parameter will force ia64_sal_cache_flush to call
1189				ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
1190	
1191		forcepae [X86-32]
1192				Forcefully enable Physical Address Extension (PAE).
1193				Many Pentium M systems disable PAE but may have a
1194				functionally usable PAE implementation.
1195				Warning: use of this parameter will taint the kernel
1196				and may cause unknown problems.
1197	
1198		ftrace=[tracer]
1199				[FTRACE] will set and start the specified tracer
1200				as early as possible in order to facilitate early
1201				boot debugging.
1202	
1203		ftrace_dump_on_oops[=orig_cpu]
1204				[FTRACE] will dump the trace buffers on oops.
1205				If no parameter is passed, ftrace will dump
1206				buffers of all CPUs, but if you pass orig_cpu, it will
1207				dump only the buffer of the CPU that triggered the
1208				oops.
1209	
1210		ftrace_filter=[function-list]
1211				[FTRACE] Limit the functions traced by the function
1212				tracer at boot up. function-list is a comma separated
1213				list of functions. This list can be changed at run
1214				time by the set_ftrace_filter file in the debugfs
1215				tracing directory.
1216	
1217		ftrace_notrace=[function-list]
1218				[FTRACE] Do not trace the functions specified in
1219				function-list. This list can be changed at run time
1220				by the set_ftrace_notrace file in the debugfs
1221				tracing directory.
1222	
1223		ftrace_graph_filter=[function-list]
1224				[FTRACE] Limit the top level callers functions traced
1225				by the function graph tracer at boot up.
1226				function-list is a comma separated list of functions
1227				that can be changed at run time by the
1228				set_graph_function file in the debugfs tracing directory.
1229	
1230		ftrace_graph_notrace=[function-list]
1231				[FTRACE] Do not trace from the functions specified in
1232				function-list.  This list is a comma separated list of
1233				functions that can be changed at run time by the
1234				set_graph_notrace file in the debugfs tracing directory.
1235	
1236		ftrace_graph_max_depth=<uint>
1237				[FTRACE] Used with the function graph tracer. This is
1238				the max depth it will trace into a function. This value
1239				can be changed at run time by the max_graph_depth file
1240				in the tracefs tracing directory. default: 0 (no limit)
1241	
1242		gamecon.map[2|3]=
1243				[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
1244				support via parallel port (up to 5 devices per port)
1245				Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1246				See also Documentation/input/devices/joystick-parport.rst
1247	
1248		gamma=		[HW,DRM]
1249	
1250		gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
1251				Format: off | on
1252				default: on
1253	
1254		gcov_persist=	[GCOV] When non-zero (default), profiling data for
1255				kernel modules is saved and remains accessible via
1256				debugfs, even when the module is unloaded/reloaded.
1257				When zero, profiling data is discarded and associated
1258				debugfs files are removed at module unload time.
1259	
1260		goldfish	[X86] Enable the goldfish android emulator platform.
1261				Don't use this when you are not running on the
1262				android emulator
1263	
1264		gpt		[EFI] Forces disk with valid GPT signature but
1265				invalid Protective MBR to be treated as GPT. If the
1266				primary GPT is corrupted, it enables the backup/alternate
1267				GPT to be used instead.
1268	
1269		grcan.enable0=	[HW] Configuration of physical interface 0. Determines
1270				the "Enable 0" bit of the configuration register.
1271				Format: 0 | 1
1272				Default: 0
1273		grcan.enable1=	[HW] Configuration of physical interface 1. Determines
1274				the "Enable 0" bit of the configuration register.
1275				Format: 0 | 1
1276				Default: 0
1277		grcan.select=	[HW] Select which physical interface to use.
1278				Format: 0 | 1
1279				Default: 0
1280		grcan.txsize=	[HW] Sets the size of the tx buffer.
1281				Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
1282				Default: 1024
1283		grcan.rxsize=	[HW] Sets the size of the rx buffer.
1284				Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
1285				Default: 1024
1286	
1287		gpio-mockup.gpio_mockup_ranges
1288				[HW] Sets the ranges of gpiochip of for this device.
1289				Format: <start1>,<end1>,<start2>,<end2>...
1290	
1291		hardlockup_all_cpu_backtrace=
1292				[KNL] Should the hard-lockup detector generate
1293				backtraces on all cpus.
1294				Format: <integer>
1295	
1296		hashdist=	[KNL,NUMA] Large hashes allocated during boot
1297				are distributed across NUMA nodes.  Defaults on
1298				for 64-bit NUMA, off otherwise.
1299				Format: 0 | 1 (for off | on)
1300	
1301		hcl=		[IA-64] SGI's Hardware Graph compatibility layer
1302	
1303		hd=		[EIDE] (E)IDE hard drive subsystem geometry
1304				Format: <cyl>,<head>,<sect>
1305	
1306		hest_disable	[ACPI]
1307				Disable Hardware Error Source Table (HEST) support;
1308				corresponding firmware-first mode error processing
1309				logic will be disabled.
1310	
1311		highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
1312				size of <nn>. This works even on boxes that have no
1313				highmem otherwise. This also works to reduce highmem
1314				size on bigger boxes.
1315	
1316		highres=	[KNL] Enable/disable high resolution timer mode.
1317				Valid parameters: "on", "off"
1318				Default: "on"
1319	
1320		hisax=		[HW,ISDN]
1321				See Documentation/isdn/README.HiSax.
1322	
1323		hlt		[BUGS=ARM,SH]
1324	
1325		hpet=		[X86-32,HPET] option to control HPET usage
1326				Format: { enable (default) | disable | force |
1327					verbose }
1328				disable: disable HPET and use PIT instead
1329				force: allow force enabled of undocumented chips (ICH4,
1330					VIA, nVidia)
1331				verbose: show contents of HPET registers during setup
1332	
1333		hpet_mmap=	[X86, HPET_MMAP] Allow userspace to mmap HPET
1334				registers.  Default set by CONFIG_HPET_MMAP_DEFAULT.
1335	
1336		hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
1337		hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
1338				On x86-64 and powerpc, this option can be specified
1339				multiple times interleaved with hugepages= to reserve
1340				huge pages of different sizes. Valid pages sizes on
1341				x86-64 are 2M (when the CPU supports "pse") and 1G
1342				(when the CPU supports the "pdpe1gb" cpuinfo flag).
1343	
1344		hvc_iucv=	[S390] Number of z/VM IUCV hypervisor console (HVC)
1345				       terminal devices. Valid values: 0..8
1346		hvc_iucv_allow=	[S390] Comma-separated list of z/VM user IDs.
1347				       If specified, z/VM IUCV HVC accepts connections
1348				       from listed z/VM user IDs only.
1349	
1350		hwthread_map=	[METAG] Comma-separated list of Linux cpu id to
1351				        hardware thread id mappings.
1352					Format: <cpu>:<hwthread>
1353	
1354		keep_bootcon	[KNL]
1355				Do not unregister boot console at start. This is only
1356				useful for debugging when something happens in the window
1357				between unregistering the boot console and initializing
1358				the real console.
1359	
1360		i2c_bus=	[HW] Override the default board specific I2C bus speed
1361				     or register an additional I2C bus that is not
1362				     registered from board initialization code.
1363				     Format:
1364				     <bus_id>,<clkrate>
1365	
1366		i8042.debug	[HW] Toggle i8042 debug mode
1367		i8042.unmask_kbd_data
1368				[HW] Enable printing of interrupt data from the KBD port
1369				     (disabled by default, and as a pre-condition
1370				     requires that i8042.debug=1 be enabled)
1371		i8042.direct	[HW] Put keyboard port into non-translated mode
1372		i8042.dumbkbd	[HW] Pretend that controller can only read data from
1373				     keyboard and cannot control its state
1374				     (Don't attempt to blink the leds)
1375		i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
1376		i8042.nokbd	[HW] Don't check/create keyboard port
1377		i8042.noloop	[HW] Disable the AUX Loopback command while probing
1378				     for the AUX port
1379		i8042.nomux	[HW] Don't check presence of an active multiplexing
1380				     controller
1381		i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1382				     controllers
1383		i8042.notimeout	[HW] Ignore timeout condition signalled by controller
1384		i8042.reset	[HW] Reset the controller during init, cleanup and
1385				     suspend-to-ram transitions, only during s2r
1386				     transitions, or never reset
1387				Format: { 1 | Y | y | 0 | N | n }
1388				1, Y, y: always reset controller
1389				0, N, n: don't ever reset controller
1390				Default: only on s2r transitions on x86; most other
1391				architectures force reset to be always executed
1392		i8042.unlock	[HW] Unlock (ignore) the keylock
1393		i8042.kbdreset  [HW] Reset device connected to KBD port
1394	
1395		i810=		[HW,DRM]
1396	
1397		i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
1398				indicates that the driver is running on unsupported
1399				hardware.
1400		i8k.force	[HW] Activate i8k driver even if SMM BIOS signature
1401				does not match list of supported models.
1402		i8k.power_status
1403				[HW] Report power status in /proc/i8k
1404				(disabled by default)
1405		i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN
1406				capability is set.
1407	
1408		i915.invert_brightness=
1409				[DRM] Invert the sense of the variable that is used to
1410				set the brightness of the panel backlight. Normally a
1411				brightness value of 0 indicates backlight switched off,
1412				and the maximum of the brightness value sets the backlight
1413				to maximum brightness. If this parameter is set to 0
1414				(default) and the machine requires it, or this parameter
1415				is set to 1, a brightness value of 0 sets the backlight
1416				to maximum brightness, and the maximum of the brightness
1417				value switches the backlight off.
1418				-1 -- never invert brightness
1419				 0 -- machine default
1420				 1 -- force brightness inversion
1421	
1422		icn=		[HW,ISDN]
1423				Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1424	
1425		ide-core.nodma=	[HW] (E)IDE subsystem
1426				Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1427				.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1428				.cdrom .chs .ignore_cable are additional options
1429				See Documentation/ide/ide.txt.
1430	
1431		ide-generic.probe-mask= [HW] (E)IDE subsystem
1432				Format: <int>
1433				Probe mask for legacy ISA IDE ports.  Depending on
1434				platform up to 6 ports are supported, enabled by
1435				setting corresponding bits in the mask to 1.  The
1436				default value is 0x0, which has a special meaning.
1437				On systems that have PCI, it triggers scanning the
1438				PCI bus for the first and the second port, which
1439				are then probed.  On systems without PCI the value
1440				of 0x0 enables probing the two first ports as if it
1441				was 0x3.
1442	
1443		ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1444				Claim all unknown PCI IDE storage controllers.
1445	
1446		idle=		[X86]
1447				Format: idle=poll, idle=halt, idle=nomwait
1448				Poll forces a polling idle loop that can slightly
1449				improve the performance of waking up a idle CPU, but
1450				will use a lot of power and make the system run hot.
1451				Not recommended.
1452				idle=halt: Halt is forced to be used for CPU idle.
1453				In such case C2/C3 won't be used again.
1454				idle=nomwait: Disable mwait for CPU C-states
1455	
1456		ieee754=	[MIPS] Select IEEE Std 754 conformance mode
1457				Format: { strict | legacy | 2008 | relaxed }
1458				Default: strict
1459	
1460				Choose which programs will be accepted for execution
1461				based on the IEEE 754 NaN encoding(s) supported by
1462				the FPU and the NaN encoding requested with the value
1463				of an ELF file header flag individually set by each
1464				binary.  Hardware implementations are permitted to
1465				support either or both of the legacy and the 2008 NaN
1466				encoding mode.
1467	
1468				Available settings are as follows:
1469				strict	accept binaries that request a NaN encoding
1470					supported by the FPU
1471				legacy	only accept legacy-NaN binaries, if supported
1472					by the FPU
1473				2008	only accept 2008-NaN binaries, if supported
1474					by the FPU
1475				relaxed	accept any binaries regardless of whether
1476					supported by the FPU
1477	
1478				The FPU emulator is always able to support both NaN
1479				encodings, so if no FPU hardware is present or it has
1480				been disabled with 'nofpu', then the settings of
1481				'legacy' and '2008' strap the emulator accordingly,
1482				'relaxed' straps the emulator for both legacy-NaN and
1483				2008-NaN, whereas 'strict' enables legacy-NaN only on
1484				legacy processors and both NaN encodings on MIPS32 or
1485				MIPS64 CPUs.
1486	
1487				The setting for ABS.fmt/NEG.fmt instruction execution
1488				mode generally follows that for the NaN encoding,
1489				except where unsupported by hardware.
1490	
1491		ignore_loglevel	[KNL]
1492				Ignore loglevel setting - this will print /all/
1493				kernel messages to the console. Useful for debugging.
1494				We also add it as printk module parameter, so users
1495				could change it dynamically, usually by
1496				/sys/module/printk/parameters/ignore_loglevel.
1497	
1498		ignore_rlimit_data
1499				Ignore RLIMIT_DATA setting for data mappings,
1500				print warning at first misuse.  Can be changed via
1501				/sys/module/kernel/parameters/ignore_rlimit_data.
1502	
1503		ihash_entries=	[KNL]
1504				Set number of hash buckets for inode cache.
1505	
1506		ima_appraise=	[IMA] appraise integrity measurements
1507				Format: { "off" | "enforce" | "fix" | "log" }
1508				default: "enforce"
1509	
1510		ima_appraise_tcb [IMA]
1511				The builtin appraise policy appraises all files
1512				owned by uid=0.
1513	
1514		ima_canonical_fmt [IMA]
1515				Use the canonical format for the binary runtime
1516				measurements, instead of host native format.
1517	
1518		ima_hash=	[IMA]
1519				Format: { md5 | sha1 | rmd160 | sha256 | sha384
1520					   | sha512 | ... }
1521				default: "sha1"
1522	
1523				The list of supported hash algorithms is defined
1524				in crypto/hash_info.h.
1525	
1526		ima_policy=	[IMA]
1527				The builtin policies to load during IMA setup.
1528				Format: "tcb | appraise_tcb | secure_boot"
1529	
1530				The "tcb" policy measures all programs exec'd, files
1531				mmap'd for exec, and all files opened with the read
1532				mode bit set by either the effective uid (euid=0) or
1533				uid=0.
1534	
1535				The "appraise_tcb" policy appraises the integrity of
1536				all files owned by root. (This is the equivalent
1537				of ima_appraise_tcb.)
1538	
1539				The "secure_boot" policy appraises the integrity
1540				of files (eg. kexec kernel image, kernel modules,
1541				firmware, policy, etc) based on file signatures.
1542	
1543		ima_tcb		[IMA] Deprecated.  Use ima_policy= instead.
1544				Load a policy which meets the needs of the Trusted
1545				Computing Base.  This means IMA will measure all
1546				programs exec'd, files mmap'd for exec, and all files
1547				opened for read by uid=0.
1548	
1549		ima_template=   [IMA]
1550				Select one of defined IMA measurements template formats.
1551				Formats: { "ima" | "ima-ng" | "ima-sig" }
1552				Default: "ima-ng"
1553	
1554		ima_template_fmt=
1555		                [IMA] Define a custom template format.
1556				Format: { "field1|...|fieldN" }
1557	
1558		ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
1559				Format: <min_file_size>
1560				Set the minimal file size for using asynchronous hash.
1561				If left unspecified, ahash usage is disabled.
1562	
1563				ahash performance varies for different data sizes on
1564				different crypto accelerators. This option can be used
1565				to achieve the best performance for a particular HW.
1566	
1567		ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
1568				Format: <bufsize>
1569				Set hashing buffer size. Default: 4k.
1570	
1571				ahash performance varies for different chunk sizes on
1572				different crypto accelerators. This option can be used
1573				to achieve best performance for particular HW.
1574	
1575		init=		[KNL]
1576				Format: <full_path>
1577				Run specified binary instead of /sbin/init as init
1578				process.
1579	
1580		initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
1581				for working out where the kernel is dying during
1582				startup.
1583	
1584		initcall_blacklist=  [KNL] Do not execute a comma-separated list of
1585				initcall functions.  Useful for debugging built-in
1586				modules and initcalls.
1587	
1588		initrd=		[BOOT] Specify the location of the initial ramdisk
1589	
1590		init_pkru=	[x86] Specify the default memory protection keys rights
1591				register contents for all processes.  0x55555554 by
1592				default (disallow access to all but pkey 0).  Can
1593				override in debugfs after boot.
1594	
1595		inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
1596				Format: <irq>
1597	
1598		int_pln_enable  [x86] Enable power limit notification interrupt
1599	
1600		integrity_audit=[IMA]
1601				Format: { "0" | "1" }
1602				0 -- basic integrity auditing messages. (Default)
1603				1 -- additional integrity auditing messages.
1604	
1605		intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
1606			on
1607				Enable intel iommu driver.
1608			off
1609				Disable intel iommu driver.
1610			igfx_off [Default Off]
1611				By default, gfx is mapped as normal device. If a gfx
1612				device has a dedicated DMAR unit, the DMAR unit is
1613				bypassed by not enabling DMAR with this option. In
1614				this case, gfx device will use physical address for
1615				DMA.
1616			forcedac [x86_64]
1617				With this option iommu will not optimize to look
1618				for io virtual address below 32-bit forcing dual
1619				address cycle on pci bus for cards supporting greater
1620				than 32-bit addressing. The default is to look
1621				for translation below 32-bit and if not available
1622				then look in the higher range.
1623			strict [Default Off]
1624				With this option on every unmap_single operation will
1625				result in a hardware IOTLB flush operation as opposed
1626				to batching them for performance.
1627			sp_off [Default Off]
1628				By default, super page will be supported if Intel IOMMU
1629				has the capability. With this option, super page will
1630				not be supported.
1631			ecs_off [Default Off]
1632				By default, extended context tables will be supported if
1633				the hardware advertises that it has support both for the
1634				extended tables themselves, and also PASID support. With
1635				this option set, extended tables will not be used even
1636				on hardware which claims to support them.
1637			tboot_noforce [Default Off]
1638				Do not force the Intel IOMMU enabled under tboot.
1639				By default, tboot will force Intel IOMMU on, which
1640				could harm performance of some high-throughput
1641				devices like 40GBit network cards, even if identity
1642				mapping is enabled.
1643				Note that using this option lowers the security
1644				provided by tboot because it makes the system
1645				vulnerable to DMA attacks.
1646	
1647		intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
1648				0	disables intel_idle and fall back on acpi_idle.
1649				1 to 9	specify maximum depth of C-state.
1650	
1651		intel_pstate=  [X86]
1652			       disable
1653			         Do not enable intel_pstate as the default
1654			         scaling driver for the supported processors
1655			       passive
1656				 Use intel_pstate as a scaling driver, but configure it
1657				 to work with generic cpufreq governors (instead of
1658				 enabling its internal governor).  This mode cannot be
1659				 used along with the hardware-managed P-states (HWP)
1660				 feature.
1661			       force
1662				 Enable intel_pstate on systems that prohibit it by default
1663				 in favor of acpi-cpufreq. Forcing the intel_pstate driver
1664				 instead of acpi-cpufreq may disable platform features, such
1665				 as thermal controls and power capping, that rely on ACPI
1666				 P-States information being indicated to OSPM and therefore
1667				 should be used with caution. This option does not work with
1668				 processors that aren't supported by the intel_pstate driver
1669				 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
1670			       no_hwp
1671			         Do not enable hardware P state control (HWP)
1672				 if available.
1673			hwp_only
1674				Only load intel_pstate on systems which support
1675				hardware P state control (HWP) if available.
1676			support_acpi_ppc
1677				Enforce ACPI _PPC performance limits. If the Fixed ACPI
1678				Description Table, specifies preferred power management
1679				profile as "Enterprise Server" or "Performance Server",
1680				then this feature is turned on by default.
1681			per_cpu_perf_limits
1682				Allow per-logical-CPU P-State performance control limits using
1683				cpufreq sysfs interface
1684	
1685		intremap=	[X86-64, Intel-IOMMU]
1686				on	enable Interrupt Remapping (default)
1687				off	disable Interrupt Remapping
1688				nosid	disable Source ID checking
1689				no_x2apic_optout
1690					BIOS x2APIC opt-out request will be ignored
1691				nopost	disable Interrupt Posting
1692	
1693		iomem=		Disable strict checking of access to MMIO memory
1694			strict	regions from userspace.
1695			relaxed
1696	
1697		iommu=		[x86]
1698			off
1699			force
1700			noforce
1701			biomerge
1702			panic
1703			nopanic
1704			merge
1705			nomerge
1706			forcesac
1707			soft
1708			pt		[x86, IA-64]
1709			nobypass	[PPC/POWERNV]
1710				Disable IOMMU bypass, using IOMMU for PCI devices.
1711	
1712		iommu.passthrough=
1713				[ARM64] Configure DMA to bypass the IOMMU by default.
1714				Format: { "0" | "1" }
1715				0 - Use IOMMU translation for DMA.
1716				1 - Bypass the IOMMU for DMA.
1717				unset - Use IOMMU translation for DMA.
1718	
1719		io7=		[HW] IO7 for Marvel based alpha systems
1720				See comment before marvel_specify_io7 in
1721				arch/alpha/kernel/core_marvel.c.
1722	
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
1732	
1733		ip=		[IP_PNP]
1734				See Documentation/filesystems/nfs/nfsroot.txt.
1735	
1736		irqaffinity=	[SMP] Set the default irq affinity mask
1737				The argument is a cpu list, as described above.
1738	
1739		irqchip.gicv2_force_probe=
1740				[ARM, ARM64]
1741				Format: <bool>
1742				Force the kernel to look for the second 4kB page
1743				of a GICv2 controller even if the memory range
1744				exposed by the device tree is too small.
1745	
1746		irqfixup	[HW]
1747				When an interrupt is not handled search all handlers
1748				for it. Intended to get systems with badly broken
1749				firmware running.
1750	
1751		irqpoll		[HW]
1752				When an interrupt is not handled search all handlers
1753				for it. Also check all handlers each timer
1754				interrupt. Intended to get systems with badly broken
1755				firmware running.
1756	
1757		isapnp=		[ISAPNP]
1758				Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1759	
1760		isolcpus=	[KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
1761				[Deprecated - use cpusets instead]
1762				Format: [flag-list,]<cpu-list>
1763	
1764				Specify one or more CPUs to isolate from disturbances
1765				specified in the flag list (default: domain):
1766	
1767				nohz
1768				  Disable the tick when a single task runs.
1769				domain
1770				  Isolate from the general SMP balancing and scheduling
1771				  algorithms. Note that performing domain isolation this way
1772				  is irreversible: it's not possible to bring back a CPU to
1773				  the domains once isolated through isolcpus. It's strongly
1774				  advised to use cpusets instead to disable scheduler load
1775				  balancing through the "cpuset.sched_load_balance" file.
1776				  It offers a much more flexible interface where CPUs can
1777				  move in and out of an isolated set anytime.
1778	
1779				  You can move a process onto or off an "isolated" CPU via
1780				  the CPU affinity syscalls or cpuset.
1781				  <cpu number> begins at 0 and the maximum value is
1782				  "number of CPUs in system - 1".
1783	
1784				The format of <cpu-list> is described above.
1785	
1786	
1787	
1788		iucv=		[HW,NET]
1789	
1790		ivrs_ioapic	[HW,X86_64]
1791				Provide an override to the IOAPIC-ID<->DEVICE-ID
1792				mapping provided in the IVRS ACPI table. For
1793				example, to map IOAPIC-ID decimal 10 to
1794				PCI device 00:14.0 write the parameter as:
1795					ivrs_ioapic[10]=00:14.0
1796	
1797		ivrs_hpet	[HW,X86_64]
1798				Provide an override to the HPET-ID<->DEVICE-ID
1799				mapping provided in the IVRS ACPI table. For
1800				example, to map HPET-ID decimal 0 to
1801				PCI device 00:14.0 write the parameter as:
1802					ivrs_hpet[0]=00:14.0
1803	
1804		ivrs_acpihid	[HW,X86_64]
1805				Provide an override to the ACPI-HID:UID<->DEVICE-ID
1806				mapping provided in the IVRS ACPI table. For
1807				example, to map UART-HID:UID AMD0020:0 to
1808				PCI device 00:14.5 write the parameter as:
1809					ivrs_acpihid[00:14.5]=AMD0020:0
1810	
1811		js=		[HW,JOY] Analog joystick
1812				See Documentation/input/joydev/joystick.rst.
1813	
1814		nokaslr		[KNL]
1815				When CONFIG_RANDOMIZE_BASE is set, this disables
1816				kernel and module base offset ASLR (Address Space
1817				Layout Randomization).
1818	
1819		kasan_multi_shot
1820				[KNL] Enforce KASAN (Kernel Address Sanitizer) to print
1821				report on every invalid memory access. Without this
1822				parameter KASAN will print report only for the first
1823				invalid access.
1824	
1825		keepinitrd	[HW,ARM]
1826	
1827		kernelcore=	[KNL,X86,IA-64,PPC]
1828				Format: nn[KMGTPE] | "mirror"
1829				This parameter
1830				specifies the amount of memory usable by the kernel
1831				for non-movable allocations.  The requested amount is
1832				spread evenly throughout all nodes in the system. The
1833				remaining memory in each node is used for Movable
1834				pages. In the event, a node is too small to have both
1835				kernelcore and Movable pages, kernelcore pages will
1836				take priority and other nodes will have a larger number
1837				of Movable pages.  The Movable zone is used for the
1838				allocation of pages that may be reclaimed or moved
1839				by the page migration subsystem.  This means that
1840				HugeTLB pages may not be allocated from this zone.
1841				Note that allocations like PTEs-from-HighMem still
1842				use the HighMem zone if it exists, and the Normal
1843				zone if it does not.
1844	
1845				Instead of specifying the amount of memory (nn[KMGTPE]),
1846				you can specify "mirror" option. In case "mirror"
1847				option is specified, mirrored (reliable) memory is used
1848				for non-movable allocations and remaining memory is used
1849				for Movable pages. nn[KMGTPE] and "mirror" are exclusive,
1850				so you can NOT specify nn[KMGTPE] and "mirror" at the same
1851				time.
1852	
1853		kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
1854				Format: <Controller#>[,poll interval]
1855				The controller # is the number of the ehci usb debug
1856				port as it is probed via PCI.  The poll interval is
1857				optional and is the number seconds in between
1858				each poll cycle to the debug port in case you need
1859				the functionality for interrupting the kernel with
1860				gdb or control-c on the dbgp connection.  When
1861				not using this parameter you use sysrq-g to break into
1862				the kernel debugger.
1863	
1864		kgdboc=		[KGDB,HW] kgdb over consoles.
1865				Requires a tty driver that supports console polling,
1866				or a supported polling keyboard driver (non-usb).
1867				 Serial only format: <serial_device>[,baud]
1868				 keyboard only format: kbd
1869				 keyboard and serial format: kbd,<serial_device>[,baud]
1870				Optional Kernel mode setting:
1871				 kms, kbd format: kms,kbd
1872				 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1873	
1874		kgdbwait	[KGDB] Stop kernel execution and enter the
1875				kernel debugger at the earliest opportunity.
1876	
1877		kmac=		[MIPS] korina ethernet MAC address.
1878				Configure the RouterBoard 532 series on-chip
1879				Ethernet adapter MAC address.
1880	
1881		kmemleak=	[KNL] Boot-time kmemleak enable/disable
1882				Valid arguments: on, off
1883				Default: on
1884				Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
1885				the default is off.
1886	
1887		kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1888				Default is 0 (don't ignore, but inject #GP)
1889	
1890		kvm.mmu_audit=	[KVM] This is a R/W parameter which allows audit
1891				KVM MMU at runtime.
1892				Default is 0 (off)
1893	
1894		kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.
1895				Default is 1 (enabled)
1896	
1897		kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)
1898				for all guests.
1899				Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1900	
1901		kvm-arm.vgic_v3_group0_trap=
1902				[KVM,ARM] Trap guest accesses to GICv3 group-0
1903				system registers
1904	
1905		kvm-arm.vgic_v3_group1_trap=
1906				[KVM,ARM] Trap guest accesses to GICv3 group-1
1907				system registers
1908	
1909		kvm-arm.vgic_v3_common_trap=
1910				[KVM,ARM] Trap guest accesses to GICv3 common
1911				system registers
1912	
1913		kvm-arm.vgic_v4_enable=
1914				[KVM,ARM] Allow use of GICv4 for direct injection of
1915				LPIs.
1916	
1917		kvm-intel.ept=	[KVM,Intel] Disable extended page tables
1918				(virtualized MMU) support on capable Intel chips.
1919				Default is 1 (enabled)
1920	
1921		kvm-intel.emulate_invalid_guest_state=
1922				[KVM,Intel] Enable emulation of invalid guest states
1923				Default is 0 (disabled)
1924	
1925		kvm-intel.flexpriority=
1926				[KVM,Intel] Disable FlexPriority feature (TPR shadow).
1927				Default is 1 (enabled)
1928	
1929		kvm-intel.nested=
1930				[KVM,Intel] Enable VMX nesting (nVMX).
1931				Default is 0 (disabled)
1932	
1933		kvm-intel.unrestricted_guest=
1934				[KVM,Intel] Disable unrestricted guest feature
1935				(virtualized real and unpaged mode) on capable
1936				Intel chips. Default is 1 (enabled)
1937	
1938		kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification
1939				feature (tagged TLBs) on capable Intel chips.
1940				Default is 1 (enabled)
1941	
1942		l2cr=		[PPC]
1943	
1944		l3cr=		[PPC]
1945	
1946		lapic		[X86-32,APIC] Enable the local APIC even if BIOS
1947				disabled it.
1948	
1949		lapic=		[x86,APIC] "notscdeadline" Do not use TSC deadline
1950				value for LAPIC timer one-shot implementation. Default
1951				back to the programmable timer unit in the LAPIC.
1952	
1953		lapic_timer_c2_ok	[X86,APIC] trust the local apic timer
1954				in C2 power state.
1955	
1956		libata.dma=	[LIBATA] DMA control
1957				libata.dma=0	  Disable all PATA and SATA DMA
1958				libata.dma=1	  PATA and SATA Disk DMA only
1959				libata.dma=2	  ATAPI (CDROM) DMA only
1960				libata.dma=4	  Compact Flash DMA only
1961				Combinations also work, so libata.dma=3 enables DMA
1962				for disks and CDROMs, but not CFs.
1963	
1964		libata.ignore_hpa=	[LIBATA] Ignore HPA limit
1965				libata.ignore_hpa=0	  keep BIOS limits (default)
1966				libata.ignore_hpa=1	  ignore limits, using full disk
1967	
1968		libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
1969				when set.
1970				Format: <int>
1971	
1972		libata.force=	[LIBATA] Force configurations.  The format is comma
1973				separated list of "[ID:]VAL" where ID is
1974				PORT[.DEVICE].  PORT and DEVICE are decimal numbers
1975				matching port, link or device.  Basically, it matches
1976				the ATA ID string printed on console by libata.  If
1977				the whole ID part is omitted, the last PORT and DEVICE
1978				values are used.  If ID hasn't been specified yet, the
1979				configuration applies to all ports, links and devices.
1980	
1981				If only DEVICE is omitted, the parameter applies to
1982				the port and all links and devices behind it.  DEVICE
1983				number of 0 either selects the first device or the
1984				first fan-out link behind PMP device.  It does not
1985				select the host link.  DEVICE number of 15 selects the
1986				host link and device attached to it.
1987	
1988				The VAL specifies the configuration to force.  As long
1989				as there's no ambiguity shortcut notation is allowed.
1990				For example, both 1.5 and 1.5G would work for 1.5Gbps.
1991				The following configurations can be forced.
1992	
1993				* Cable type: 40c, 80c, short40c, unk, ign or sata.
1994				  Any ID with matching PORT is used.
1995	
1996				* SATA link speed limit: 1.5Gbps or 3.0Gbps.
1997	
1998				* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1999				  udma[/][16,25,33,44,66,100,133] notation is also
2000				  allowed.
2001	
2002				* [no]ncq: Turn on or off NCQ.
2003	
2004				* [no]ncqtrim: Turn off queued DSM TRIM.
2005	
2006				* nohrst, nosrst, norst: suppress hard, soft
2007	                          and both resets.
2008	
2009				* rstonce: only attempt one reset during
2010				  hot-unplug link recovery
2011	
2012				* dump_id: dump IDENTIFY data.
2013	
2014				* atapi_dmadir: Enable ATAPI DMADIR bridge support
2015	
2016				* disable: Disable this device.
2017	
2018				If there are multiple matching configurations changing
2019				the same attribute, the last one is used.
2020	
2021		memblock=debug	[KNL] Enable memblock debug messages.
2022	
2023		load_ramdisk=	[RAM] List of ramdisks to load from floppy
2024				See Documentation/blockdev/ramdisk.txt.
2025	
2026		lockd.nlm_grace_period=P  [NFS] Assign grace period.
2027				Format: <integer>
2028	
2029		lockd.nlm_tcpport=N	[NFS] Assign TCP port.
2030				Format: <integer>
2031	
2032		lockd.nlm_timeout=T	[NFS] Assign timeout value.
2033				Format: <integer>
2034	
2035		lockd.nlm_udpport=M	[NFS] Assign UDP port.
2036				Format: <integer>
2037	
2038		locktorture.nreaders_stress= [KNL]
2039				Set the number of locking read-acquisition kthreads.
2040				Defaults to being automatically set based on the
2041				number of online CPUs.
2042	
2043		locktorture.nwriters_stress= [KNL]
2044				Set the number of locking write-acquisition kthreads.
2045	
2046		locktorture.onoff_holdoff= [KNL]
2047				Set time (s) after boot for CPU-hotplug testing.
2048	
2049		locktorture.onoff_interval= [KNL]
2050				Set time (s) between CPU-hotplug operations, or
2051				zero to disable CPU-hotplug testing.
2052	
2053		locktorture.shuffle_interval= [KNL]
2054				Set task-shuffle interval (jiffies).  Shuffling
2055				tasks allows some CPUs to go into dyntick-idle
2056				mode during the locktorture test.
2057	
2058		locktorture.shutdown_secs= [KNL]
2059				Set time (s) after boot system shutdown.  This
2060				is useful for hands-off automated testing.
2061	
2062		locktorture.stat_interval= [KNL]
2063				Time (s) between statistics printk()s.
2064	
2065		locktorture.stutter= [KNL]
2066				Time (s) to stutter testing, for example,
2067				specifying five seconds causes the test to run for
2068				five seconds, wait for five seconds, and so on.
2069				This tests the locking primitive's ability to
2070				transition abruptly to and from idle.
2071	
2072		locktorture.torture_type= [KNL]
2073				Specify the locking implementation to test.
2074	
2075		locktorture.verbose= [KNL]
2076				Enable additional printk() statements.
2077	
2078		logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
2079				Format: <irq>
2080	
2081		loglevel=	All Kernel Messages with a loglevel smaller than the
2082				console loglevel will be printed to the console. It can
2083				also be changed with klogd or other programs. The
2084				loglevels are defined as follows:
2085	
2086				0 (KERN_EMERG)		system is unusable
2087				1 (KERN_ALERT)		action must be taken immediately
2088				2 (KERN_CRIT)		critical conditions
2089				3 (KERN_ERR)		error conditions
2090				4 (KERN_WARNING)	warning conditions
2091				5 (KERN_NOTICE)		normal but significant condition
2092				6 (KERN_INFO)		informational
2093				7 (KERN_DEBUG)		debug-level messages
2094	
2095		log_buf_len=n[KMG]	Sets the size of the printk ring buffer,
2096				in bytes.  n must be a power of two and greater
2097				than the minimal size. The minimal size is defined
2098				by LOG_BUF_SHIFT kernel config parameter. There is
2099				also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
2100				that allows to increase the default size depending on
2101				the number of CPUs. See init/Kconfig for more details.
2102	
2103		logo.nologo	[FB] Disables display of the built-in Linux logo.
2104				This may be used to provide more screen space for
2105				kernel log messages and is useful when debugging
2106				kernel boot problems.
2107	
2108		lp=0		[LP]	Specify parallel ports to use, e.g,
2109		lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
2110		lp=reset		first parallel port). 'lp=0' disables the
2111		lp=auto			printer driver. 'lp=reset' (which can be
2112					specified in addition to the ports) causes
2113					attached printers to be reset. Using
2114					lp=port1,port2,... specifies the parallel ports
2115					to associate lp devices with, starting with
2116					lp0. A port specification may be 'none' to skip
2117					that lp device, or a parport name such as
2118					'parport0'. Specifying 'lp=auto' instead of a
2119					port specification list means that device IDs
2120					from each port should be examined, to see if
2121					an IEEE 1284-compliant printer is attached; if
2122					so, the driver will manage that printer.
2123					See also header of drivers/char/lp.c.
2124	
2125		lpj=n		[KNL]
2126				Sets loops_per_jiffy to given constant, thus avoiding
2127				time-consuming boot-time autodetection (up to 250 ms per
2128				CPU). 0 enables autodetection (default). To determine
2129				the correct value for your kernel, boot with normal
2130				autodetection and see what value is printed. Note that
2131				on SMP systems the preset will be applied to all CPUs,
2132				which is likely to cause problems if your CPUs need
2133				significantly divergent settings. An incorrect value
2134				will cause delays in the kernel to be wrong, leading to
2135				unpredictable I/O errors and other breakage. Although
2136				unlikely, in the extreme case this might damage your
2137				hardware.
2138	
2139		ltpc=		[NET]
2140				Format: <io>,<irq>,<dma>
2141	
2142		machvec=	[IA-64] Force the use of a particular machine-vector
2143				(machvec) in a generic kernel.
2144				Example: machvec=hpzx1_swiotlb
2145	
2146		machtype=	[Loongson] Share the same kernel image file between different
2147				 yeeloong laptop.
2148				Example: machtype=lemote-yeeloong-2f-7inch
2149	
2150		max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater
2151				than or equal to this physical address is ignored.
2152	
2153		maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
2154				will bring up during bootup.  maxcpus=n : n >= 0 limits
2155				the kernel to bring up 'n' processors. Surely after
2156				bootup you can bring up the other plugged cpu by executing
2157				"echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus
2158				only takes effect during system bootup.
2159				While n=0 is a special case, it is equivalent to "nosmp",
2160				which also disables the IO APIC.
2161	
2162		max_loop=	[LOOP] The number of loop block devices that get
2163		(loop.max_loop)	unconditionally pre-created at init time. The default
2164				number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
2165				of statically allocating a predefined number, loop
2166				devices can be requested on-demand with the
2167				/dev/loop-control interface.
2168	
2169		mce		[X86-32] Machine Check Exception
2170	
2171		mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.txt
2172	
2173		md=		[HW] RAID subsystems devices and level
2174				See Documentation/admin-guide/md.rst.
2175	
2176		mdacon=		[MDA]
2177				Format: <first>,<last>
2178				Specifies range of consoles to be captured by the MDA.
2179	
2180		mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
2181				Amount of memory to be used when the kernel is not able
2182				to see the whole system memory or for test.
2183				[X86] Work as limiting max address. Use together
2184				with memmap= to avoid physical address space collisions.
2185				Without memmap= PCI devices could be placed at addresses
2186				belonging to unused RAM.
2187	
2188		mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
2189				memory.
2190	
2191		memchunk=nn[KMG]
2192				[KNL,SH] Allow user to override the default size for
2193				per-device physically contiguous DMA buffers.
2194	
2195	        memhp_default_state=online/offline
2196				[KNL] Set the initial state for the memory hotplug
2197				onlining policy. If not specified, the default value is
2198				set according to the
2199				CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
2200				option.
2201				See Documentation/memory-hotplug.txt.
2202	
2203		memmap=exactmap	[KNL,X86] Enable setting of an exact
2204				E820 memory map, as specified by the user.
2205				Such memmap=exactmap lines can be constructed based on
2206				BIOS output or other requirements. See the memmap=nn@ss
2207				option description.
2208	
2209		memmap=nn[KMG]@ss[KMG]
2210				[KNL] Force usage of a specific region of memory.
2211				Region of memory to be used is from ss to ss+nn.
2212				If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG],
2213				which limits max address to nn[KMG].
2214				Multiple different regions can be specified,
2215				comma delimited.
2216				Example:
2217					memmap=100M@2G,100M#3G,1G!1024G
2218	
2219		memmap=nn[KMG]#ss[KMG]
2220				[KNL,ACPI] Mark specific memory as ACPI data.
2221				Region of memory to be marked is from ss to ss+nn.
2222	
2223		memmap=nn[KMG]$ss[KMG]
2224				[KNL,ACPI] Mark specific memory as reserved.
2225				Region of memory to be reserved is from ss to ss+nn.
2226				Example: Exclude memory from 0x18690000-0x1869ffff
2227				         memmap=64K$0x18690000
2228				         or
2229				         memmap=0x10000$0x18690000
2230				Some bootloaders may need an escape character before '$',
2231				like Grub2, otherwise '$' and the following number
2232				will be eaten.
2233	
2234		memmap=nn[KMG]!ss[KMG]
2235				[KNL,X86] Mark specific memory as protected.
2236				Region of memory to be used, from ss to ss+nn.
2237				The memory region may be marked as e820 type 12 (0xc)
2238				and is NVDIMM or ADR memory.
2239	
2240		memory_corruption_check=0/1 [X86]
2241				Some BIOSes seem to corrupt the first 64k of
2242				memory when doing things like suspend/resume.
2243				Setting this option will scan the memory
2244				looking for corruption.  Enabling this will
2245				both detect corruption and prevent the kernel
2246				from using the memory being corrupted.
2247				However, its intended as a diagnostic tool; if
2248				repeatable BIOS-originated corruption always
2249				affects the same memory, you can use memmap=
2250				to prevent the kernel from using that memory.
2251	
2252		memory_corruption_check_size=size [X86]
2253				By default it checks for corruption in the low
2254				64k, making this memory unavailable for normal
2255				use.  Use this parameter to scan for
2256				corruption in more or less memory.
2257	
2258		memory_corruption_check_period=seconds [X86]
2259				By default it checks for corruption every 60
2260				seconds.  Use this parameter to check at some
2261				other rate.  0 disables periodic checking.
2262	
2263		memtest=	[KNL,X86,ARM] Enable memtest
2264				Format: <integer>
2265				default : 0 <disable>
2266				Specifies the number of memtest passes to be
2267				performed. Each pass selects another test
2268				pattern from a given set of patterns. Memtest
2269				fills the memory with this pattern, validates
2270				memory contents and reserves bad memory
2271				regions that are detected.
2272	
2273		mem_encrypt=	[X86-64] AMD Secure Memory Encryption (SME) control
2274				Valid arguments: on, off
2275				Default (depends on kernel configuration option):
2276				  on  (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y)
2277				  off (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n)
2278				mem_encrypt=on:		Activate SME
2279				mem_encrypt=off:	Do not activate SME
2280	
2281				Refer to Documentation/x86/amd-memory-encryption.txt
2282				for details on when memory encryption can be activated.
2283	
2284		mem_sleep_default=	[SUSPEND] Default system suspend mode:
2285				s2idle  - Suspend-To-Idle
2286				shallow - Power-On Suspend or equivalent (if supported)
2287				deep    - Suspend-To-RAM or equivalent (if supported)
2288				See Documentation/admin-guide/pm/sleep-states.rst.
2289	
2290		meye.*=		[HW] Set MotionEye Camera parameters
2291				See Documentation/media/v4l-drivers/meye.rst.
2292	
2293		mfgpt_irq=	[IA-32] Specify the IRQ to use for the
2294				Multi-Function General Purpose Timers on AMD Geode
2295				platforms.
2296	
2297		mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
2298				the BIOS has incorrectly applied a workaround. TinyBIOS
2299				version 0.98 is known to be affected, 0.99 fixes the
2300				problem by letting the user disable the workaround.
2301	
2302		mga=		[HW,DRM]
2303	
2304		min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this
2305				physical address is ignored.
2306	
2307		mini2440=	[ARM,HW,KNL]
2308				Format:[0..2][b][c][t]
2309				Default: "0tb"
2310				MINI2440 configuration specification:
2311				0 - The attached screen is the 3.5" TFT
2312				1 - The attached screen is the 7" TFT
2313				2 - The VGA Shield is attached (1024x768)
2314				Leaving out the screen size parameter will not load
2315				the TFT driver, and the framebuffer will be left
2316				unconfigured.
2317				b - Enable backlight. The TFT backlight pin will be
2318				linked to the kernel VESA blanking code and a GPIO
2319				LED. This parameter is not necessary when using the
2320				VGA shield.
2321				c - Enable the s3c camera interface.
2322				t - Reserved for enabling touchscreen support. The
2323				touchscreen support is not enabled in the mainstream
2324				kernel as of 2.6.30, a preliminary port can be found
2325				in the "bleeding edge" mini2440 support kernel at
2326				http://repo.or.cz/w/linux-2.6/mini2440.git
2327	
2328		mminit_loglevel=
2329				[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
2330				parameter allows control of the logging verbosity for
2331				the additional memory initialisation checks. A value
2332				of 0 disables mminit logging and a level of 4 will
2333				log everything. Information is printed at KERN_DEBUG
2334				so loglevel=8 may also need to be specified.
2335	
2336		module.sig_enforce
2337				[KNL] When CONFIG_MODULE_SIG is set, this means that
2338				modules without (valid) signatures will fail to load.
2339				Note that if CONFIG_MODULE_SIG_FORCE is set, that
2340				is always true, so this option does nothing.
2341	
2342		module_blacklist=  [KNL] Do not load a comma-separated list of
2343				modules.  Useful for debugging problem modules.
2344	
2345		mousedev.tap_time=
2346				[MOUSE] Maximum time between finger touching and
2347				leaving touchpad surface for touch to be considered
2348				a tap and be reported as a left button click (for
2349				touchpads working in absolute mode only).
2350				Format: <msecs>
2351		mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
2352				reporting absolute coordinates, such as tablets
2353		mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
2354				reporting absolute coordinates, such as tablets
2355	
2356		movablecore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
2357				is similar to kernelcore except it specifies the
2358				amount of memory used for migratable allocations.
2359				If both kernelcore and movablecore is specified,
2360				then kernelcore will be at *least* the specified
2361				value but may be more. If movablecore on its own
2362				is specified, the administrator must be careful
2363				that the amount of memory usable for all allocations
2364				is not too small.
2365	
2366		movable_node	[KNL] Boot-time switch to make hotplugable memory
2367				NUMA nodes to be movable. This means that the memory
2368				of such nodes will be usable only for movable
2369				allocations which rules out almost all kernel
2370				allocations. Use with caution!
2371	
2372		MTD_Partition=	[MTD]
2373				Format: <name>,<region-number>,<size>,<offset>
2374	
2375		MTD_Region=	[MTD] Format:
2376				<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
2377	
2378		mtdparts=	[MTD]
2379				See drivers/mtd/cmdlinepart.c.
2380	
2381		multitce=off	[PPC]  This parameter disables the use of the pSeries
2382				firmware feature for updating multiple TCE entries
2383				at a time.
2384	
2385		onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
2386	
2387				Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
2388	
2389				boundary - index of last SLC block on Flex-OneNAND.
2390					   The remaining blocks are configured as MLC blocks.
2391				lock	 - Configure if Flex-OneNAND boundary should be locked.
2392					   Once locked, the boundary cannot be changed.
2393					   1 indicates lock status, 0 indicates unlock status.
2394	
2395		mtdset=		[ARM]
2396				ARM/S3C2412 JIVE boot control
2397	
2398				See arch/arm/mach-s3c2412/mach-jive.c
2399	
2400		mtouchusb.raw_coordinates=
2401				[HW] Make the MicroTouch USB driver use raw coordinates
2402				('y', default) or cooked coordinates ('n')
2403	
2404		mtrr_chunk_size=nn[KMG] [X86]
2405				used for mtrr cleanup. It is largest continuous chunk
2406				that could hold holes aka. UC entries.
2407	
2408		mtrr_gran_size=nn[KMG] [X86]
2409				Used for mtrr cleanup. It is granularity of mtrr block.
2410				Default is 1.
2411				Large value could prevent small alignment from
2412				using up MTRRs.
2413	
2414		mtrr_spare_reg_nr=n [X86]
2415				Format: <integer>
2416				Range: 0,7 : spare reg number
2417				Default : 1
2418				Used for mtrr cleanup. It is spare mtrr entries number.
2419				Set to 2 or more if your graphical card needs more.
2420	
2421		n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card
2422	
2423		netdev=		[NET] Network devices parameters
2424				Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
2425				Note that mem_start is often overloaded to mean
2426				something different and driver-specific.
2427				This usage is only documented in each driver source
2428				file if at all.
2429	
2430		nf_conntrack.acct=
2431				[NETFILTER] Enable connection tracking flow accounting
2432				0 to disable accounting
2433				1 to enable accounting
2434				Default value is 0.
2435	
2436		nfsaddrs=	[NFS] Deprecated.  Use ip= instead.
2437				See Documentation/filesystems/nfs/nfsroot.txt.
2438	
2439		nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
2440				See Documentation/filesystems/nfs/nfsroot.txt.
2441	
2442		nfsrootdebug	[NFS] enable nfsroot debugging messages.
2443				See Documentation/filesystems/nfs/nfsroot.txt.
2444	
2445		nfs.callback_nr_threads=
2446				[NFSv4] set the total number of threads that the
2447				NFS client will assign to service NFSv4 callback
2448				requests.
2449	
2450		nfs.callback_tcpport=
2451				[NFS] set the TCP port on which the NFSv4 callback
2452				channel should listen.
2453	
2454		nfs.cache_getent=
2455				[NFS] sets the pathname to the program which is used
2456				to update the NFS client cache entries.
2457	
2458		nfs.cache_getent_timeout=
2459				[NFS] sets the timeout after which an attempt to
2460				update a cache entry is deemed to have failed.
2461	
2462		nfs.idmap_cache_timeout=
2463				[NFS] set the maximum lifetime for idmapper cache
2464				entries.
2465	
2466		nfs.enable_ino64=
2467				[NFS] enable 64-bit inode numbers.
2468				If zero, the NFS client will fake up a 32-bit inode
2469				number for the readdir() and stat() syscalls instead
2470				of returning the full 64-bit number.
2471				The default is to return 64-bit inode numbers.
2472	
2473		nfs.max_session_cb_slots=
2474				[NFSv4.1] Sets the maximum number of session
2475				slots the client will assign to the callback
2476				channel. This determines the maximum number of
2477				callbacks the client will process in parallel for
2478				a particular server.
2479	
2480		nfs.max_session_slots=
2481				[NFSv4.1] Sets the maximum number of session slots
2482				the client will attempt to negotiate with the server.
2483				This limits the number of simultaneous RPC requests
2484				that the client can send to the NFSv4.1 server.
2485				Note that there is little point in setting this
2486				value higher than the max_tcp_slot_table_limit.
2487	
2488		nfs.nfs4_disable_idmapping=
2489				[NFSv4] When set to the default of '1', this option
2490				ensures that both the RPC level authentication
2491				scheme and the NFS level operations agree to use
2492				numeric uids/gids if the mount is using the
2493				'sec=sys' security flavour. In effect it is
2494				disabling idmapping, which can make migration from
2495				legacy NFSv2/v3 systems to NFSv4 easier.
2496				Servers that do not support this mode of operation
2497				will be autodetected by the client, and it will fall
2498				back to using the idmapper.
2499				To turn off this behaviour, set the value to '0'.
2500		nfs.nfs4_unique_id=
2501				[NFS4] Specify an additional fixed unique ident-
2502				ification string that NFSv4 clients can insert into
2503				their nfs_client_id4 string.  This is typically a
2504				UUID that is generated at system install time.
2505	
2506		nfs.send_implementation_id =
2507				[NFSv4.1] Send client implementation identification
2508				information in exchange_id requests.
2509				If zero, no implementation identification information
2510				will be sent.
2511				The default is to send the implementation identification
2512				information.
2513	
2514		nfs.recover_lost_locks =
2515				[NFSv4] Attempt to recover locks that were lost due
2516				to a lease timeout on the server. Please note that
2517				doing this risks data corruption, since there are
2518				no guarantees that the file will remain unchanged
2519				after the locks are lost.
2520				If you want to enable the kernel legacy behaviour of
2521				attempting to recover these locks, then set this
2522				parameter to '1'.
2523				The default parameter value of '0' causes the kernel
2524				not to attempt recovery of lost locks.
2525	
2526		nfs4.layoutstats_timer =
2527				[NFSv4.2] Change the rate at which the kernel sends
2528				layoutstats to the pNFS metadata server.
2529	
2530				Setting this to value to 0 causes the kernel to use
2531				whatever value is the default set by the layout
2532				driver. A non-zero value sets the minimum interval
2533				in seconds between layoutstats transmissions.
2534	
2535		nfsd.nfs4_disable_idmapping=
2536				[NFSv4] When set to the default of '1', the NFSv4
2537				server will return only numeric uids and gids to
2538				clients using auth_sys, and will accept numeric uids
2539				and gids from such clients.  This is intended to ease
2540				migration from NFSv2/v3.
2541	
2542		nmi_debug=	[KNL,SH] Specify one or more actions to take
2543				when a NMI is triggered.
2544				Format: [state][,regs][,debounce][,die]
2545	
2546		nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels
2547				Format: [panic,][nopanic,][num]
2548				Valid num: 0 or 1
2549				0 - turn hardlockup detector in nmi_watchdog off
2550				1 - turn hardlockup detector in nmi_watchdog on
2551				When panic is specified, panic when an NMI watchdog
2552				timeout occurs (or 'nopanic' to override the opposite
2553				default). To disable both hard and soft lockup detectors,
2554				please see 'nowatchdog'.
2555				This is useful when you use a panic=... timeout and
2556				need the box quickly up again.
2557	
2558				These settings can be accessed at runtime via
2559				the nmi_watchdog and hardlockup_panic sysctls.
2560	
2561		netpoll.carrier_timeout=
2562				[NET] Specifies amount of time (in seconds) that
2563				netpoll should wait for a carrier. By default netpoll
2564				waits 4 seconds.
2565	
2566		no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
2567				emulation library even if a 387 maths coprocessor
2568				is present.
2569	
2570		no_console_suspend
2571				[HW] Never suspend the console
2572				Disable suspending of consoles during suspend and
2573				hibernate operations.  Once disabled, debugging
2574				messages can reach various consoles while the rest
2575				of the system is being put to sleep (ie, while
2576				debugging driver suspend/resume hooks).  This may
2577				not work reliably with all consoles, but is known
2578				to work with serial and VGA consoles.
2579				To facilitate more flexible debugging, we also add
2580				console_suspend, a printk module parameter to control
2581				it. Users could use console_suspend (usually
2582				/sys/module/printk/parameters/console_suspend) to
2583				turn on/off it dynamically.
2584	
2585		noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
2586				caches in the slab allocator.  Saves per-node memory,
2587				but will impact performance.
2588	
2589		noalign		[KNL,ARM]
2590	
2591		noaltinstr	[S390] Disables alternative instructions patching
2592				(CPU alternatives feature).
2593	
2594		noapic		[SMP,APIC] Tells the kernel to not make use of any
2595				IOAPICs that may be present in the system.
2596	
2597		noautogroup	Disable scheduler automatic task group creation.
2598	
2599		nobats		[PPC] Do not use BATs for mapping kernel lowmem
2600				on "Classic" PPC cores.
2601	
2602		nocache		[ARM]
2603	
2604		noclflush	[BUGS=X86] Don't use the CLFLUSH instruction
2605	
2606		nodelayacct	[KNL] Disable per-task delay accounting
2607	
2608		nodsp		[SH] Disable hardware DSP at boot time.
2609	
2610		noefi		Disable EFI runtime services support.
2611	
2612		noexec		[IA-64]
2613	
2614		noexec		[X86]
2615				On X86-32 available only on PAE configured kernels.
2616				noexec=on: enable non-executable mappings (default)
2617				noexec=off: disable non-executable mappings
2618	
2619		nosmap		[X86]
2620				Disable SMAP (Supervisor Mode Access Prevention)
2621				even if it is supported by processor.
2622	
2623		nosmep		[X86]
2624				Disable SMEP (Supervisor Mode Execution Prevention)
2625				even if it is supported by processor.
2626	
2627		noexec32	[X86-64]
2628				This affects only 32-bit executables.
2629				noexec32=on: enable non-executable mappings (default)
2630					read doesn't imply executable mappings
2631				noexec32=off: disable non-executable mappings
2632					read implies executable mappings
2633	
2634		nofpu		[MIPS,SH] Disable hardware FPU at boot time.
2635	
2636		nofxsr		[BUGS=X86-32] Disables x86 floating point extended
2637				register save and restore. The kernel will only save
2638				legacy floating-point registers on task switch.
2639	
2640		nohugeiomap	[KNL,x86] Disable kernel huge I/O mappings.
2641	
2642		nosmt		[KNL,S390] Disable symmetric multithreading (SMT).
2643				Equivalent to smt=1.
2644	
2645		nospectre_v2	[X86] Disable all mitigations for the Spectre variant 2
2646				(indirect branch prediction) vulnerability. System may
2647				allow data leaks with this option, which is equivalent
2648				to spectre_v2=off.
2649	
2650		noxsave		[BUGS=X86] Disables x86 extended register state save
2651				and restore using xsave. The kernel will fallback to
2652				enabling legacy floating-point and sse state.
2653	
2654		noxsaveopt	[X86] Disables xsaveopt used in saving x86 extended
2655				register states. The kernel will fall back to use
2656				xsave to save the states. By using this parameter,
2657				performance of saving the states is degraded because
2658				xsave doesn't support modified optimization while
2659				xsaveopt supports it on xsaveopt enabled systems.
2660	
2661		noxsaves	[X86] Disables xsaves and xrstors used in saving and
2662				restoring x86 extended register state in compacted
2663				form of xsave area. The kernel will fall back to use
2664				xsaveopt and xrstor to save and restore the states
2665				in standard form of xsave area. By using this
2666				parameter, xsave area per process might occupy more
2667				memory on xsaves enabled systems.
2668	
2669		nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
2670				wfi(ARM) instruction doesn't work correctly and not to
2671				use it. This is also useful when using JTAG debugger.
2672	
2673		no_file_caps	Tells the kernel not to honor file capabilities.  The
2674				only way then for a file to be executed with privilege
2675				is to be setuid root or executed by root.
2676	
2677		nohalt		[IA-64] Tells the kernel not to use the power saving
2678				function PAL_HALT_LIGHT when idle. This increases
2679				power-consumption. On the positive side, it reduces
2680				interrupt wake-up latency, which may improve performance
2681				in certain environments such as networked servers or
2682				real-time systems.
2683	
2684		nohibernate	[HIBERNATION] Disable hibernation and resume.
2685	
2686		nohz=		[KNL] Boottime enable/disable dynamic ticks
2687				Valid arguments: on, off
2688				Default: on
2689	
2690		nohz_full=	[KNL,BOOT,SMP,ISOL]
2691				The argument is a cpu list, as described above.
2692				In kernels built with CONFIG_NO_HZ_FULL=y, set
2693				the specified list of CPUs whose tick will be stopped
2694				whenever possible. The boot CPU will be forced outside
2695				the range to maintain the timekeeping.  Any CPUs
2696				in this list will have their RCU callbacks offloaded,
2697				just as if they had also been called out in the
2698				rcu_nocbs= boot parameter.
2699	
2700		noiotrap	[SH] Disables trapped I/O port accesses.
2701	
2702		noirqdebug	[X86-32] Disables the code which attempts to detect and
2703				disable unhandled interrupt sources.
2704	
2705		no_timer_check	[X86,APIC] Disables the code which tests for
2706				broken timer IRQ sources.
2707	
2708		noisapnp	[ISAPNP] Disables ISA PnP code.
2709	
2710		noinitrd	[RAM] Tells the kernel not to load any configured
2711				initial RAM disk.
2712	
2713		nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt
2714				remapping.
2715				[Deprecated - use intremap=off]
2716	
2717		nointroute	[IA-64]
2718	
2719		noinvpcid	[X86] Disable the INVPCID cpu feature.
2720	
2721		nojitter	[IA-64] Disables jitter checking for ITC timers.
2722	
2723		no-kvmclock	[X86,KVM] Disable paravirtualized KVM clock driver
2724	
2725		no-kvmapf	[X86,KVM] Disable paravirtualized asynchronous page
2726				fault handling.
2727	
2728		no-vmw-sched-clock
2729				[X86,PV_OPS] Disable paravirtualized VMware scheduler
2730				clock and use the default one.
2731	
2732		no-steal-acc    [X86,KVM] Disable paravirtualized steal time accounting.
2733				steal time is computed, but won't influence scheduler
2734				behaviour
2735	
2736		nolapic		[X86-32,APIC] Do not enable or use the local APIC.
2737	
2738		nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
2739	
2740		noltlbs		[PPC] Do not use large page/tlb entries for kernel
2741				lowmem mapping on PPC40x and PPC8xx
2742	
2743		nomca		[IA-64] Disable machine check abort handling
2744	
2745		nomce		[X86-32] Disable Machine Check Exception
2746	
2747		nomfgpt		[X86-32] Disable Multi-Function General Purpose
2748				Timer usage (for AMD Geode machines).
2749	
2750		nonmi_ipi	[X86] Disable using NMI IPIs during panic/reboot to
2751				shutdown the other cpus.  Instead use the REBOOT_VECTOR
2752				irq.
2753	
2754		nomodule	Disable module load
2755	
2756		nopat		[X86] Disable PAT (page attribute table extension of
2757				pagetables) support.
2758	
2759		nopcid		[X86-64] Disable the PCID cpu feature.
2760	
2761		norandmaps	Don't use address space randomization.  Equivalent to
2762				echo 0 > /proc/sys/kernel/randomize_va_space
2763	
2764		noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
2765				with UP alternatives
2766	
2767		nordrand	[X86] Disable kernel use of the RDRAND and
2768				RDSEED instructions even if they are supported
2769				by the processor.  RDRAND and RDSEED are still
2770				available to user space applications.
2771	
2772		noresume	[SWSUSP] Disables resume and restores original swap
2773				space.
2774	
2775		no-scroll	[VGA] Disables scrollback.
2776				This is required for the Braillex ib80-piezo Braille
2777				reader made by F.H. Papenmeier (Germany).
2778	
2779		nosbagart	[IA-64]
2780	
2781		nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
2782	
2783		nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
2784				and disable the IO APIC.  legacy for "maxcpus=0".
2785	
2786		nosoftlockup	[KNL] Disable the soft-lockup detector.
2787	
2788		nosync		[HW,M68K] Disables sync negotiation for all devices.
2789	
2790		notsc		[BUGS=X86-32] Disable Time Stamp Counter
2791	
2792		nowatchdog	[KNL] Disable both lockup detectors, i.e.
2793	                        soft-lockup and NMI watchdog (hard-lockup).
2794	
2795		nowb		[ARM]
2796	
2797		nox2apic	[X86-64,APIC] Do not enable x2APIC mode.
2798	
2799		cpu0_hotplug	[X86] Turn on CPU0 hotplug feature when
2800				CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
2801				Some features depend on CPU0. Known dependencies are:
2802				1. Resume from suspend/hibernate depends on CPU0.
2803				Suspend/hibernate will fail if CPU0 is offline and you
2804				need to online CPU0 before suspend/hibernate.
2805				2. PIC interrupts also depend on CPU0. CPU0 can't be
2806				removed if a PIC interrupt is detected.
2807				It's said poweroff/reboot may depend on CPU0 on some
2808				machines although I haven't seen such issues so far
2809				after CPU0 is offline on a few tested machines.
2810				If the dependencies are under your control, you can
2811				turn on cpu0_hotplug.
2812	
2813		nps_mtm_hs_ctr= [KNL,ARC]
2814				This parameter sets the maximum duration, in
2815				cycles, each HW thread of the CTOP can run
2816				without interruptions, before HW switches it.
2817				The actual maximum duration is 16 times this
2818				parameter's value.
2819				Format: integer between 1 and 255
2820				Default: 255
2821	
2822		nptcg=		[IA-64] Override max number of concurrent global TLB
2823				purges which is reported from either PAL_VM_SUMMARY or
2824				SAL PALO.
2825	
2826		nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
2827				could support.  nr_cpus=n : n >= 1 limits the kernel to
2828				support 'n' processors. It could be larger than the
2829				number of already plugged CPU during bootup, later in
2830				runtime you can physically add extra cpu until it reaches
2831				n. So during boot up some boot time memory for per-cpu
2832				variables need be pre-allocated for later physical cpu
2833				hot plugging.
2834	
2835		nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
2836	
2837		numa_balancing=	[KNL,X86] Enable or disable automatic NUMA balancing.
2838				Allowed values are enable and disable
2839	
2840		numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2841				'node', 'default' can be specified
2842				This can be set from sysctl after boot.
2843				See Documentation/sysctl/vm.txt for details.
2844	
2845		ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
2846				See Documentation/debugging-via-ohci1394.txt for more
2847				info.
2848	
2849		olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2850				Rather than timing out after 20 ms if an EC
2851				command is not properly ACKed, override the length
2852				of the timeout.  We have interrupts disabled while
2853				waiting for the ACK, so if this is set too high
2854				interrupts *may* be lost!
2855	
2856		omap_mux=	[OMAP] Override bootloader pin multiplexing.
2857				Format: <mux_mode0.mode_name=value>...
2858				For example, to override I2C bus2:
2859				omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2860	
2861		oprofile.timer=	[HW]
2862				Use timer interrupt instead of performance counters
2863	
2864		oprofile.cpu_type=	Force an oprofile cpu type
2865				This might be useful if you have an older oprofile
2866				userland or if you want common events.
2867				Format: { arch_perfmon }
2868				arch_perfmon: [X86] Force use of architectural
2869					perfmon on Intel CPUs instead of the
2870					CPU specific event set.
2871				timer: [X86] Force use of architectural NMI
2872					timer mode (see also oprofile.timer
2873					for generic hr timer mode)
2874	
2875		oops=panic	Always panic on oopses. Default is to just kill the
2876				process, but there is a small probability of
2877				deadlocking the machine.
2878				This will also cause panics on machine check exceptions.
2879				Useful together with panic=30 to trigger a reboot.
2880	
2881		OSS		[HW,OSS]
2882				See Documentation/sound/oss/oss-parameters.txt
2883	
2884		page_owner=	[KNL] Boot-time page_owner enabling option.
2885				Storage of the information about who allocated
2886				each page is disabled in default. With this switch,
2887				we can turn it on.
2888				on: enable the feature
2889	
2890		page_poison=	[KNL] Boot-time parameter changing the state of
2891				poisoning on the buddy allocator.
2892				off: turn off poisoning
2893				on: turn on poisoning
2894	
2895		panic=		[KNL] Kernel behaviour on panic: delay <timeout>
2896				timeout > 0: seconds before rebooting
2897				timeout = 0: wait forever
2898				timeout < 0: reboot immediately
2899				Format: <timeout>
2900	
2901		panic_on_warn	panic() instead of WARN().  Useful to cause kdump
2902				on a WARN().
2903	
2904		crash_kexec_post_notifiers
2905				Run kdump after running panic-notifiers and dumping
2906				kmsg. This only for the users who doubt kdump always
2907				succeeds in any situation.
2908				Note that this also increases risks of kdump failure,
2909				because some panic notifiers can make the crashed
2910				kernel more unstable.
2911	
2912		parkbd.port=	[HW] Parallel port number the keyboard adapter is
2913				connected to, default is 0.
2914				Format: <parport#>
2915		parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
2916				0 for XT, 1 for AT (default is AT).
2917				Format: <mode>
2918	
2919		parport=	[HW,PPT] Specify parallel ports. 0 disables.
2920				Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2921				Use 'auto' to force the driver to use any
2922				IRQ/DMA settings detected (the default is to
2923				ignore detected IRQ/DMA settings because of
2924				possible conflicts). You can specify the base
2925				address, IRQ, and DMA settings; IRQ and DMA
2926				should be numbers, or 'auto' (for using detected
2927				settings on that particular port), or 'nofifo'
2928				(to avoid using a FIFO even if it is detected).
2929				Parallel ports are assigned in the order they
2930				are specified on the command line, starting
2931				with parport0.
2932	
2933		parport_init_mode=	[HW,PPT]
2934				Configure VIA parallel port to operate in
2935				a specific mode. This is necessary on Pegasos
2936				computer where firmware has no options for setting
2937				up parallel port mode and sets it to spp.
2938				Currently this function knows 686a and 8231 chips.
2939				Format: [spp|ps2|epp|ecp|ecpepp]
2940	
2941		pause_on_oops=
2942				Halt all CPUs after the first oops has been printed for
2943				the specified number of seconds.  This is to be used if
2944				your oopses keep scrolling off the screen.
2945	
2946		pcbit=		[HW,ISDN]
2947	
2948		pcd.		[PARIDE]
2949				See header of drivers/block/paride/pcd.c.
2950				See also Documentation/blockdev/paride.txt.
2951	
2952		pci=option[,option...]	[PCI] various PCI subsystem options:
2953			earlydump	[X86] dump PCI config space before the kernel
2954				        changes anything
2955			off		[X86] don't probe for the PCI bus
2956			bios		[X86-32] force use of PCI BIOS, don't access
2957					the hardware directly. Use this if your machine
2958					has a non-standard PCI host bridge.
2959			nobios		[X86-32] disallow use of PCI BIOS, only direct
2960					hardware access methods are allowed. Use this
2961					if you experience crashes upon bootup and you
2962					suspect they are caused by the BIOS.
2963			conf1		[X86] Force use of PCI Configuration Access
2964					Mechanism 1 (config address in IO port 0xCF8,
2965					data in IO port 0xCFC, both 32-bit).
2966			conf2		[X86] Force use of PCI Configuration Access
2967					Mechanism 2 (IO port 0xCF8 is an 8-bit port for
2968					the function, IO port 0xCFA, also 8-bit, sets
2969					bus number. The config space is then accessed
2970					through ports 0xC000-0xCFFF).
2971					See http://wiki.osdev.org/PCI for more info
2972					on the configuration access mechanisms.
2973			noaer		[PCIE] If the PCIEAER kernel config parameter is
2974					enabled, this kernel boot option can be used to
2975					disable the use of PCIE advanced error reporting.
2976			nodomains	[PCI] Disable support for multiple PCI
2977					root domains (aka PCI segments, in ACPI-speak).
2978			nommconf	[X86] Disable use of MMCONFIG for PCI
2979					Configuration
2980			check_enable_amd_mmconf [X86] check for and enable
2981					properly configured MMIO access to PCI
2982					config space on AMD family 10h CPU
2983			nomsi		[MSI] If the PCI_MSI kernel config parameter is
2984					enabled, this kernel boot option can be used to
2985					disable the use of MSI interrupts system-wide.
2986			noioapicquirk	[APIC] Disable all boot interrupt quirks.
2987					Safety option to keep boot IRQs enabled. This
2988					should never be necessary.
2989			ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
2990					primary IO-APIC for bridges that cannot disable
2991					boot IRQs. This fixes a source of spurious IRQs
2992					when the system masks IRQs.
2993			noioapicreroute	[APIC] Disable workaround that uses the
2994					boot IRQ equivalent of an IRQ that connects to
2995					a chipset where boot IRQs cannot be disabled.
2996					The opposite of ioapicreroute.
2997			biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
2998					routing table. These calls are known to be buggy
2999					on several machines and they hang the machine
3000					when used, but on other computers it's the only
3001					way to get the interrupt routing table. Try
3002					this option if the kernel is unable to allocate
3003					IRQs or discover secondary PCI buses on your
3004					motherboard.
3005			rom		[X86] Assign address space to expansion ROMs.
3006					Use with caution as certain devices share
3007					address decoders between ROMs and other
3008					resources.
3009			norom		[X86] Do not assign address space to
3010					expansion ROMs that do not already have
3011					BIOS assigned address ranges.
3012			nobar		[X86] Do not assign address space to the
3013					BARs that weren't assigned by the BIOS.
3014			irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
3015					assigned automatically to PCI devices. You can
3016					make the kernel exclude IRQs of your ISA cards
3017					this way.
3018			pirqaddr=0xAAAAA	[X86] Specify the physical address
3019					of the PIRQ table (normally generated
3020					by the BIOS) if it is outside the
3021					F0000h-100000h range.
3022			lastbus=N	[X86] Scan all buses thru bus #N. Can be
3023					useful if the kernel is unable to find your
3024					secondary buses and you want to tell it
3025					explicitly which ones they are.
3026			assign-busses	[X86] Always assign all PCI bus
3027					numbers ourselves, overriding
3028					whatever the firmware may have done.
3029			usepirqmask	[X86] Honor the possible IRQ mask stored
3030					in the BIOS $PIR table. This is needed on
3031					some systems with broken BIOSes, notably
3032					some HP Pavilion N5400 and Omnibook XE3
3033					notebooks. This will have no effect if ACPI
3034					IRQ routing is enabled.
3035			noacpi		[X86] Do not use ACPI for IRQ routing
3036					or for PCI scanning.
3037			use_crs		[X86] Use PCI host bridge window information
3038					from ACPI.  On BIOSes from 2008 or later, this
3039					is enabled by default.  If you need to use this,
3040					please report a bug.
3041			nocrs		[X86] Ignore PCI host bridge windows from ACPI.
3042				        If you need to use this, please report a bug.
3043			routeirq	Do IRQ routing for all PCI devices.
3044					This is normally done in pci_enable_device(),
3045					so this option is a temporary workaround
3046					for broken drivers that don't call it.
3047			skip_isa_align	[X86] do not align io start addr, so can
3048					handle more pci cards
3049			noearly		[X86] Don't do any early type 1 scanning.
3050					This might help on some broken boards which
3051					machine check when some devices' config space
3052					is read. But various workarounds are disabled
3053					and some IOMMU drivers will not work.
3054			bfsort		Sort PCI devices into breadth-first order.
3055					This sorting is done to get a device
3056					order compatible with older (<= 2.4) kernels.
3057			nobfsort	Don't sort PCI devices into breadth-first order.
3058			pcie_bus_tune_off	Disable PCIe MPS (Max Payload Size)
3059					tuning and use the BIOS-configured MPS defaults.
3060			pcie_bus_safe	Set every device's MPS to the largest value
3061					supported by all devices below the root complex.
3062			pcie_bus_perf	Set device MPS to the largest allowable MPS
3063					based on its parent bus. Also set MRRS (Max
3064					Read Request Size) to the largest supported
3065					value (no larger than the MPS that the device
3066					or bus can support) for best performance.
3067			pcie_bus_peer2peer	Set every device's MPS to 128B, which
3068					every device is guaranteed to support. This
3069					configuration allows peer-to-peer DMA between
3070					any pair of devices, possibly at the cost of
3071					reduced performance.  This also guarantees
3072					that hot-added devices will work.
3073			cbiosize=nn[KMG]	The fixed amount of bus space which is
3074					reserved for the CardBus bridge's IO window.
3075					The default value is 256 bytes.
3076			cbmemsize=nn[KMG]	The fixed amount of bus space which is
3077					reserved for the CardBus bridge's memory
3078					window. The default value is 64 megabytes.
3079			resource_alignment=
3080					Format:
3081					[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
3082					[<order of align>@]pci:<vendor>:<device>\
3083							[:<subvendor>:<subdevice>][; ...]
3084					Specifies alignment and device to reassign
3085					aligned memory resources.
3086					If <order of align> is not specified,
3087					PAGE_SIZE is used as alignment.
3088					PCI-PCI bridge can be specified, if resource
3089					windows need to be expanded.
3090					To specify the alignment for several
3091					instances of a device, the PCI vendor,
3092					device, subvendor, and subdevice may be
3093					specified, e.g., 4096@pci:8086:9c22:103c:198f
3094			ecrc=		Enable/disable PCIe ECRC (transaction layer
3095					end-to-end CRC checking).
3096					bios: Use BIOS/firmware settings. This is the
3097					the default.
3098					off: Turn ECRC off
3099					on: Turn ECRC on.
3100			hpiosize=nn[KMG]	The fixed amount of bus space which is
3101					reserved for hotplug bridge's IO window.
3102					Default size is 256 bytes.
3103			hpmemsize=nn[KMG]	The fixed amount of bus space which is
3104					reserved for hotplug bridge's memory window.
3105					Default size is 2 megabytes.
3106			hpbussize=nn	The minimum amount of additional bus numbers
3107					reserved for buses below a hotplug bridge.
3108					Default is 1.
3109			realloc=	Enable/disable reallocating PCI bridge resources
3110					if allocations done by BIOS are too small to
3111					accommodate resources required by all child
3112					devices.
3113					off: Turn realloc off
3114					on: Turn realloc on
3115			realloc		same as realloc=on
3116			noari		do not use PCIe ARI.
3117			pcie_scan_all	Scan all possible PCIe devices.  Otherwise we
3118					only look for one device below a PCIe downstream
3119					port.
3120			big_root_window	Try to add a big 64bit memory window to the PCIe
3121					root complex on AMD CPUs. Some GFX hardware
3122					can resize a BAR to allow access to all VRAM.
3123					Adding the window is slightly risky (it may
3124					conflict with unreported devices), so this
3125					taints the kernel.
3126	
3127		pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
3128				Management.
3129			off	Disable ASPM.
3130			force	Enable ASPM even on devices that claim not to support it.
3131				WARNING: Forcing ASPM on may cause system lockups.
3132	
3133		pcie_hp=	[PCIE] PCI Express Hotplug driver options:
3134			nomsi	Do not use MSI for PCI Express Native Hotplug (this
3135				makes all PCIe ports use INTx for hotplug services).
3136	
3137		pcie_ports=	[PCIE] PCIe ports handling:
3138			auto	Ask the BIOS whether or not to use native PCIe services
3139				associated with PCIe ports (PME, hot-plug, AER).  Use
3140				them only if that is allowed by the BIOS.
3141			native	Use native PCIe services associated with PCIe ports
3142				unconditionally.
3143			compat	Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
3144				ports driver.
3145	
3146		pcie_port_pm=	[PCIE] PCIe port power management handling:
3147			off	Disable power management of all PCIe ports
3148			force	Forcibly enable power management of all PCIe ports
3149	
3150		pcie_pme=	[PCIE,PM] Native PCIe PME signaling options:
3151			nomsi	Do not use MSI for native PCIe PME signaling (this makes
3152				all PCIe root ports use INTx for all services).
3153	
3154		pcmv=		[HW,PCMCIA] BadgePAD 4
3155	
3156		pd_ignore_unused
3157				[PM]
3158				Keep all power-domains already enabled by bootloader on,
3159				even if no driver has claimed them. This is useful
3160				for debug and development, but should not be
3161				needed on a platform with proper driver support.
3162	
3163		pd.		[PARIDE]
3164				See Documentation/blockdev/paride.txt.
3165	
3166		pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
3167				boot time.
3168				Format: { 0 | 1 }
3169				See arch/parisc/kernel/pdc_chassis.c
3170	
3171		percpu_alloc=	Select which percpu first chunk allocator to use.
3172				Currently supported values are "embed" and "page".
3173				Archs may support subset or none of the	selections.
3174				See comments in mm/percpu.c for details on each
3175				allocator.  This parameter is primarily	for debugging
3176				and performance comparison.
3177	
3178		pf.		[PARIDE]
3179				See Documentation/blockdev/paride.txt.
3180	
3181		pg.		[PARIDE]
3182				See Documentation/blockdev/paride.txt.
3183	
3184		pirq=		[SMP,APIC] Manual mp-table setup
3185				See Documentation/x86/i386/IO-APIC.txt.
3186	
3187		plip=		[PPT,NET] Parallel port network link
3188				Format: { parport<nr> | timid | 0 }
3189				See also Documentation/admin-guide/parport.rst.
3190	
3191		pmtmr=		[X86] Manual setup of pmtmr I/O Port.
3192				Override pmtimer IOPort with a hex value.
3193				e.g. pmtmr=0x508
3194	
3195		pnp.debug=1	[PNP]
3196				Enable PNP debug messages (depends on the
3197				CONFIG_PNP_DEBUG_MESSAGES option).  Change at run-time
3198				via /sys/module/pnp/parameters/debug.  We always show
3199				current resource usage; turning this on also shows
3200				possible settings and some assignment information.
3201	
3202		pnpacpi=	[ACPI]
3203				{ off }
3204	
3205		pnpbios=	[ISAPNP]
3206				{ on | off | curr | res | no-curr | no-res }
3207	
3208		pnp_reserve_irq=
3209				[ISAPNP] Exclude IRQs for the autoconfiguration
3210	
3211		pnp_reserve_dma=
3212				[ISAPNP] Exclude DMAs for the autoconfiguration
3213	
3214		pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
3215				Ranges are in pairs (I/O port base and size).
3216	
3217		pnp_reserve_mem=
3218				[ISAPNP] Exclude memory regions for the
3219				autoconfiguration.
3220				Ranges are in pairs (memory base and size).
3221	
3222		ports=		[IP_VS_FTP] IPVS ftp helper module
3223				Default is 21.
3224				Up to 8 (IP_VS_APP_MAX_PORTS) ports
3225				may be specified.
3226				Format: <port>,<port>....
3227	
3228		powersave=off	[PPC] This option disables power saving features.
3229				It specifically disables cpuidle and sets the
3230				platform machine description specific power_save
3231				function to NULL. On Idle the CPU just reduces
3232				execution priority.
3233	
3234		ppc_strict_facility_enable
3235				[PPC] This option catches any kernel floating point,
3236				Altivec, VSX and SPE outside of regions specifically
3237				allowed (eg kernel_enable_fpu()/kernel_disable_fpu()).
3238				There is some performance impact when enabling this.
3239	
3240		ppc_tm=		[PPC]
3241				Format: {"off"}
3242				Disable Hardware Transactional Memory
3243	
3244		print-fatal-signals=
3245				[KNL] debug: print fatal signals
3246	
3247				If enabled, warn about various signal handling
3248				related application anomalies: too many signals,
3249				too many POSIX.1 timers, fatal signals causing a
3250				coredump - etc.
3251	
3252				If you hit the warning due to signal overflow,
3253				you might want to try "ulimit -i unlimited".
3254	
3255				default: off.
3256	
3257		printk.always_kmsg_dump=
3258				Trigger kmsg_dump for cases other than kernel oops or
3259				panics
3260				Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
3261				default: disabled
3262	
3263		printk.devkmsg={on,off,ratelimit}
3264				Control writing to /dev/kmsg.
3265				on - unlimited logging to /dev/kmsg from userspace
3266				off - logging to /dev/kmsg disabled
3267				ratelimit - ratelimit the logging
3268				Default: ratelimit
3269	
3270		printk.time=	Show timing data prefixed to each printk message line
3271				Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
3272	
3273		processor.max_cstate=	[HW,ACPI]
3274				Limit processor to maximum C-state
3275				max_cstate=9 overrides any DMI blacklist limit.
3276	
3277		processor.nocst	[HW,ACPI]
3278				Ignore the _CST method to determine C-states,
3279				instead using the legacy FADT method
3280	
3281		profile=	[KNL] Enable kernel profiling via /proc/profile
3282				Format: [<profiletype>,]<number>
3283				Param: <profiletype>: "schedule", "sleep", or "kvm"
3284					[defaults to kernel profiling]
3285				Param: "schedule" - profile schedule points.
3286				Param: "sleep" - profile D-state sleeping (millisecs).
3287					Requires CONFIG_SCHEDSTATS
3288				Param: "kvm" - profile VM exits.
3289				Param: <number> - step/bucket size as a power of 2 for
3290					statistical time based profiling.
3291	
3292		prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk
3293				before loading.
3294				See Documentation/blockdev/ramdisk.txt.
3295	
3296		psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
3297				probe for; one of (bare|imps|exps|lifebook|any).
3298		psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
3299				per second.
3300		psmouse.resetafter=	[HW,MOUSE]
3301				Try to reset the device after so many bad packets
3302				(0 = never).
3303		psmouse.resolution=
3304				[HW,MOUSE] Set desired mouse resolution, in dpi.
3305		psmouse.smartscroll=
3306				[HW,MOUSE] Controls Logitech smartscroll autorepeat.
3307				0 = disabled, 1 = enabled (default).
3308	
3309		pstore.backend=	Specify the name of the pstore backend to use
3310	
3311		pt.		[PARIDE]
3312				See Documentation/blockdev/paride.txt.
3313	
3314		pti=		[X86_64] Control Page Table Isolation of user and
3315				kernel address spaces.  Disabling this feature
3316				removes hardening, but improves performance of
3317				system calls and interrupts.
3318	
3319				on   - unconditionally enable
3320				off  - unconditionally disable
3321				auto - kernel detects whether your CPU model is
3322				       vulnerable to issues that PTI mitigates
3323	
3324				Not specifying this option is equivalent to pti=auto.
3325	
3326		nopti		[X86_64]
3327				Equivalent to pti=off
3328	
3329		pty.legacy_count=
3330				[KNL] Number of legacy pty's. Overwrites compiled-in
3331				default number.
3332	
3333		quiet		[KNL] Disable most log messages
3334	
3335		r128=		[HW,DRM]
3336	
3337		raid=		[HW,RAID]
3338				See Documentation/admin-guide/md.rst.
3339	
3340		ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
3341				See Documentation/blockdev/ramdisk.txt.
3342	
3343		ras=option[,option,...]	[KNL] RAS-specific options
3344	
3345			cec_disable	[X86]
3346					Disable the Correctable Errors Collector,
3347					see CONFIG_RAS_CEC help text.
3348	
3349		rcu_nocbs=	[KNL]
3350				The argument is a cpu list, as described above.
3351	
3352				In kernels built with CONFIG_RCU_NOCB_CPU=y, set
3353				the specified list of CPUs to be no-callback CPUs.
3354				Invocation of these CPUs' RCU callbacks will
3355				be offloaded to "rcuox/N" kthreads created for
3356				that purpose, where "x" is "b" for RCU-bh, "p"
3357				for RCU-preempt, and "s" for RCU-sched, and "N"
3358				is the CPU number.  This reduces OS jitter on the
3359				offloaded CPUs, which can be useful for HPC and
3360				real-time workloads.  It can also improve energy
3361				efficiency for asymmetric multiprocessors.
3362	
3363		rcu_nocb_poll	[KNL]
3364				Rather than requiring that offloaded CPUs
3365				(specified by rcu_nocbs= above) explicitly
3366				awaken the corresponding "rcuoN" kthreads,
3367				make these kthreads poll for callbacks.
3368				This improves the real-time response for the
3369				offloaded CPUs by relieving them of the need to
3370				wake up the corresponding kthread, but degrades
3371				energy efficiency by requiring that the kthreads
3372				periodically wake up to do the polling.
3373	
3374		rcutree.blimit=	[KNL]
3375				Set maximum number of finished RCU callbacks to
3376				process in one batch.
3377	
3378		rcutree.dump_tree=	[KNL]
3379				Dump the structure of the rcu_node combining tree
3380				out at early boot.  This is used for diagnostic
3381				purposes, to verify correct tree setup.
3382	
3383		rcutree.gp_cleanup_delay=	[KNL]
3384				Set the number of jiffies to delay each step of
3385				RCU grace-period cleanup.
3386	
3387		rcutree.gp_init_delay=	[KNL]
3388				Set the number of jiffies to delay each step of
3389				RCU grace-period initialization.
3390	
3391		rcutree.gp_preinit_delay=	[KNL]
3392				Set the number of jiffies to delay each step of
3393				RCU grace-period pre-initialization, that is,
3394				the propagation of recent CPU-hotplug changes up
3395				the rcu_node combining tree.
3396	
3397		rcutree.rcu_fanout_exact= [KNL]
3398				Disable autobalancing of the rcu_node combining
3399				tree.  This is used by rcutorture, and might
3400				possibly be useful for architectures having high
3401				cache-to-cache transfer latencies.
3402	
3403		rcutree.rcu_fanout_leaf= [KNL]
3404				Change the number of CPUs assigned to each
3405				leaf rcu_node structure.  Useful for very
3406				large systems, which will choose the value 64,
3407				and for NUMA systems with large remote-access
3408				latencies, which will choose a value aligned
3409				with the appropriate hardware boundaries.
3410	
3411		rcutree.jiffies_till_sched_qs= [KNL]
3412				Set required age in jiffies for a
3413				given grace period before RCU starts
3414				soliciting quiescent-state help from
3415				rcu_note_context_switch().
3416	
3417		rcutree.jiffies_till_first_fqs= [KNL]
3418				Set delay from grace-period initialization to
3419				first attempt to force quiescent states.
3420				Units are jiffies, minimum value is zero,
3421				and maximum value is HZ.
3422	
3423		rcutree.jiffies_till_next_fqs= [KNL]
3424				Set delay between subsequent attempts to force
3425				quiescent states.  Units are jiffies, minimum
3426				value is one, and maximum value is HZ.
3427	
3428		rcutree.kthread_prio= 	 [KNL,BOOT]
3429				Set the SCHED_FIFO priority of the RCU per-CPU
3430				kthreads (rcuc/N). This value is also used for
3431				the priority of the RCU boost threads (rcub/N)
3432				and for the RCU grace-period kthreads (rcu_bh,
3433				rcu_preempt, and rcu_sched). If RCU_BOOST is
3434				set, valid values are 1-99 and the default is 1
3435				(the least-favored priority).  Otherwise, when
3436				RCU_BOOST is not set, valid values are 0-99 and
3437				the default is zero (non-realtime operation).
3438	
3439		rcutree.rcu_nocb_leader_stride= [KNL]
3440				Set the number of NOCB kthread groups, which
3441				defaults to the square root of the number of
3442				CPUs.  Larger numbers reduces the wakeup overhead
3443				on the per-CPU grace-period kthreads, but increases
3444				that same overhead on each group's leader.
3445	
3446		rcutree.qhimark= [KNL]
3447				Set threshold of queued RCU callbacks beyond which
3448				batch limiting is disabled.
3449	
3450		rcutree.qlowmark= [KNL]
3451				Set threshold of queued RCU callbacks below which
3452				batch limiting is re-enabled.
3453	
3454		rcutree.rcu_idle_gp_delay= [KNL]
3455				Set wakeup interval for idle CPUs that have
3456				RCU callbacks (RCU_FAST_NO_HZ=y).
3457	
3458		rcutree.rcu_idle_lazy_gp_delay= [KNL]
3459				Set wakeup interval for idle CPUs that have
3460				only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
3461				Lazy RCU callbacks are those which RCU can
3462				prove do nothing more than free memory.
3463	
3464		rcutree.rcu_kick_kthreads= [KNL]
3465				Cause the grace-period kthread to get an extra
3466				wake_up() if it sleeps three times longer than
3467				it should at force-quiescent-state time.
3468				This wake_up() will be accompanied by a
3469				WARN_ONCE() splat and an ftrace_dump().
3470	
3471		rcuperf.gp_async= [KNL]
3472				Measure performance of asynchronous
3473				grace-period primitives such as call_rcu().
3474	
3475		rcuperf.gp_async_max= [KNL]
3476				Specify the maximum number of outstanding
3477				callbacks per writer thread.  When a writer
3478				thread exceeds this limit, it invokes the
3479				corresponding flavor of rcu_barrier() to allow
3480				previously posted callbacks to drain.
3481	
3482		rcuperf.gp_exp= [KNL]
3483				Measure performance of expedited synchronous
3484				grace-period primitives.
3485	
3486		rcuperf.holdoff= [KNL]
3487				Set test-start holdoff period.  The purpose of
3488				this parameter is to delay the start of the
3489				test until boot completes in order to avoid
3490				interference.
3491	
3492		rcuperf.nreaders= [KNL]
3493				Set number of RCU readers.  The value -1 selects
3494				N, where N is the number of CPUs.  A value
3495				"n" less than -1 selects N-n+1, where N is again
3496				the number of CPUs.  For example, -2 selects N
3497				(the number of CPUs), -3 selects N+1, and so on.
3498				A value of "n" less than or equal to -N selects
3499				a single reader.
3500	
3501		rcuperf.nwriters= [KNL]
3502				Set number of RCU writers.  The values operate
3503				the same as for rcuperf.nreaders.
3504				N, where N is the number of CPUs
3505	
3506		rcuperf.perf_type= [KNL]
3507				Specify the RCU implementation to test.
3508	
3509		rcuperf.shutdown= [KNL]
3510				Shut the system down after performance tests
3511				complete.  This is useful for hands-off automated
3512				testing.
3513	
3514		rcuperf.verbose= [KNL]
3515				Enable additional printk() statements.
3516	
3517		rcuperf.writer_holdoff= [KNL]
3518				Write-side holdoff between grace periods,
3519				in microseconds.  The default of zero says
3520				no holdoff.
3521	
3522		rcutorture.cbflood_inter_holdoff= [KNL]
3523				Set holdoff time (jiffies) between successive
3524				callback-flood tests.
3525	
3526		rcutorture.cbflood_intra_holdoff= [KNL]
3527				Set holdoff time (jiffies) between successive
3528				bursts of callbacks within a given callback-flood
3529				test.
3530	
3531		rcutorture.cbflood_n_burst= [KNL]
3532				Set the number of bursts making up a given
3533				callback-flood test.  Set this to zero to
3534				disable callback-flood testing.
3535	
3536		rcutorture.cbflood_n_per_burst= [KNL]
3537				Set the number of callbacks to be registered
3538				in a given burst of a callback-flood test.
3539	
3540		rcutorture.fqs_duration= [KNL]
3541				Set duration of force_quiescent_state bursts
3542				in microseconds.
3543	
3544		rcutorture.fqs_holdoff= [KNL]
3545				Set holdoff time within force_quiescent_state bursts
3546				in microseconds.
3547	
3548		rcutorture.fqs_stutter= [KNL]
3549				Set wait time between force_quiescent_state bursts
3550				in seconds.
3551	
3552		rcutorture.gp_cond= [KNL]
3553				Use conditional/asynchronous update-side
3554				primitives, if available.
3555	
3556		rcutorture.gp_exp= [KNL]
3557				Use expedited update-side primitives, if available.
3558	
3559		rcutorture.gp_normal= [KNL]
3560				Use normal (non-expedited) asynchronous
3561				update-side primitives, if available.
3562	
3563		rcutorture.gp_sync= [KNL]
3564				Use normal (non-expedited) synchronous
3565				update-side primitives, if available.  If all
3566				of rcutorture.gp_cond=, rcutorture.gp_exp=,
3567				rcutorture.gp_normal=, and rcutorture.gp_sync=
3568				are zero, rcutorture acts as if is interpreted
3569				they are all non-zero.
3570	
3571		rcutorture.n_barrier_cbs= [KNL]
3572				Set callbacks/threads for rcu_barrier() testing.
3573	
3574		rcutorture.nfakewriters= [KNL]
3575				Set number of concurrent RCU writers.  These just
3576				stress RCU, they don't participate in the actual
3577				test, hence the "fake".
3578	
3579		rcutorture.nreaders= [KNL]
3580				Set number of RCU readers.  The value -1 selects
3581				N-1, where N is the number of CPUs.  A value
3582				"n" less than -1 selects N-n-2, where N is again
3583				the number of CPUs.  For example, -2 selects N
3584				(the number of CPUs), -3 selects N+1, and so on.
3585	
3586		rcutorture.object_debug= [KNL]
3587				Enable debug-object double-call_rcu() testing.
3588	
3589		rcutorture.onoff_holdoff= [KNL]
3590				Set time (s) after boot for CPU-hotplug testing.
3591	
3592		rcutorture.onoff_interval= [KNL]
3593				Set time (s) between CPU-hotplug operations, or
3594				zero to disable CPU-hotplug testing.
3595	
3596		rcutorture.shuffle_interval= [KNL]
3597				Set task-shuffle interval (s).  Shuffling tasks
3598				allows some CPUs to go into dyntick-idle mode
3599				during the rcutorture test.
3600	
3601		rcutorture.shutdown_secs= [KNL]
3602				Set time (s) after boot system shutdown.  This
3603				is useful for hands-off automated testing.
3604	
3605		rcutorture.stall_cpu= [KNL]
3606				Duration of CPU stall (s) to test RCU CPU stall
3607				warnings, zero to disable.
3608	
3609		rcutorture.stall_cpu_holdoff= [KNL]
3610				Time to wait (s) after boot before inducing stall.
3611	
3612		rcutorture.stall_cpu_irqsoff= [KNL]
3613				Disable interrupts while stalling if set.
3614	
3615		rcutorture.stat_interval= [KNL]
3616				Time (s) between statistics printk()s.
3617	
3618		rcutorture.stutter= [KNL]
3619				Time (s) to stutter testing, for example, specifying
3620				five seconds causes the test to run for five seconds,
3621				wait for five seconds, and so on.  This tests RCU's
3622				ability to transition abruptly to and from idle.
3623	
3624		rcutorture.test_boost= [KNL]
3625				Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
3626				"Maybe" means test if the RCU implementation
3627				under test support RCU priority boosting.
3628	
3629		rcutorture.test_boost_duration= [KNL]
3630				Duration (s) of each individual boost test.
3631	
3632		rcutorture.test_boost_interval= [KNL]
3633				Interval (s) between each boost test.
3634	
3635		rcutorture.test_no_idle_hz= [KNL]
3636				Test RCU's dyntick-idle handling.  See also the
3637				rcutorture.shuffle_interval parameter.
3638	
3639		rcutorture.torture_type= [KNL]
3640				Specify the RCU implementation to test.
3641	
3642		rcutorture.verbose= [KNL]
3643				Enable additional printk() statements.
3644	
3645		rcupdate.rcu_cpu_stall_suppress= [KNL]
3646				Suppress RCU CPU stall warning messages.
3647	
3648		rcupdate.rcu_cpu_stall_timeout= [KNL]
3649				Set timeout for RCU CPU stall warning messages.
3650	
3651		rcupdate.rcu_expedited= [KNL]
3652				Use expedited grace-period primitives, for
3653				example, synchronize_rcu_expedited() instead
3654				of synchronize_rcu().  This reduces latency,
3655				but can increase CPU utilization, degrade
3656				real-time latency, and degrade energy efficiency.
3657				No effect on CONFIG_TINY_RCU kernels.
3658	
3659		rcupdate.rcu_normal= [KNL]
3660				Use only normal grace-period primitives,
3661				for example, synchronize_rcu() instead of
3662				synchronize_rcu_expedited().  This improves
3663				real-time latency, CPU utilization, and
3664				energy efficiency, but can expose users to
3665				increased grace-period latency.  This parameter
3666				overrides rcupdate.rcu_expedited.  No effect on
3667				CONFIG_TINY_RCU kernels.
3668	
3669		rcupdate.rcu_normal_after_boot= [KNL]
3670				Once boot has completed (that is, after
3671				rcu_end_inkernel_boot() has been invoked), use
3672				only normal grace-period primitives.  No effect
3673				on CONFIG_TINY_RCU kernels.
3674	
3675		rcupdate.rcu_task_stall_timeout= [KNL]
3676				Set timeout in jiffies for RCU task stall warning
3677				messages.  Disable with a value less than or equal
3678				to zero.
3679	
3680		rcupdate.rcu_self_test= [KNL]
3681				Run the RCU early boot self tests
3682	
3683		rcupdate.rcu_self_test_bh= [KNL]
3684				Run the RCU bh early boot self tests
3685	
3686		rcupdate.rcu_self_test_sched= [KNL]
3687				Run the RCU sched early boot self tests
3688	
3689		rdinit=		[KNL]
3690				Format: <full_path>
3691				Run specified binary instead of /init from the ramdisk,
3692				used for early userspace startup. See initrd.
3693	
3694		rdt=		[HW,X86,RDT]
3695				Turn on/off individual RDT features. List is:
3696				cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
3697				mba.
3698				E.g. to turn on cmt and turn off mba use:
3699					rdt=cmt,!mba
3700	
3701		reboot=		[KNL]
3702				Format (x86 or x86_64):
3703					[w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
3704					[[,]s[mp]#### \
3705					[[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
3706					[[,]f[orce]
3707				Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
3708				      reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
3709				      reboot_force is either force or not specified,
3710				      reboot_cpu is s[mp]#### with #### being the processor
3711						to be used for rebooting.
3712	
3713		relax_domain_level=
3714				[KNL, SMP] Set scheduler's default relax_domain_level.
3715				See Documentation/cgroup-v1/cpusets.txt.
3716	
3717		reserve=	[KNL,BUGS] Force kernel to ignore I/O ports or memory
3718				Format: <base1>,<size1>[,<base2>,<size2>,...]
3719				Reserve I/O ports or memory so the kernel won't use
3720				them.  If <base> is less than 0x10000, the region
3721				is assumed to be I/O ports; otherwise it is memory.
3722	
3723		reservetop=	[X86-32]
3724				Format: nn[KMG]
3725				Reserves a hole at the top of the kernel virtual
3726				address space.
3727	
3728		reservelow=	[X86]
3729				Format: nn[K]
3730				Set the amount of memory to reserve for BIOS at
3731				the bottom of the address space.
3732	
3733		reset_devices	[KNL] Force drivers to reset the underlying device
3734				during initialization.
3735	
3736		resume=		[SWSUSP]
3737				Specify the partition device for software suspend
3738				Format:
3739				{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
3740	
3741		resume_offset=	[SWSUSP]
3742				Specify the offset from the beginning of the partition
3743				given by "resume=" at which the swap header is located,
3744				in <PAGE_SIZE> units (needed only for swap files).
3745				See  Documentation/power/swsusp-and-swap-files.txt
3746	
3747		resumedelay=	[HIBERNATION] Delay (in seconds) to pause before attempting to
3748				read the resume files
3749	
3750		resumewait	[HIBERNATION] Wait (indefinitely) for resume device to show up.
3751				Useful for devices that are detected asynchronously
3752				(e.g. USB and MMC devices).
3753	
3754		hibernate=	[HIBERNATION]
3755			noresume	Don't check if there's a hibernation image
3756					present during boot.
3757			nocompress	Don't compress/decompress hibernation images.
3758			no		Disable hibernation and resume.
3759			protect_image	Turn on image protection during restoration
3760					(that will set all pages holding image data
3761					during restoration read-only).
3762	
3763		retain_initrd	[RAM] Keep initrd memory after extraction
3764	
3765		rfkill.default_state=
3766			0	"airplane mode".  All wifi, bluetooth, wimax, gps, fm,
3767				etc. communication is blocked by default.
3768			1	Unblocked.
3769	
3770		rfkill.master_switch_mode=
3771			0	The "airplane mode" button does nothing.
3772			1	The "airplane mode" button toggles between everything
3773				blocked and the previous configuration.
3774			2	The "airplane mode" button toggles between everything
3775				blocked and everything unblocked.
3776	
3777		rhash_entries=	[KNL,NET]
3778				Set number of hash buckets for route cache
3779	
3780		ring3mwait=disable
3781				[KNL] Disable ring 3 MONITOR/MWAIT feature on supported
3782				CPUs.
3783	
3784		ro		[KNL] Mount root device read-only on boot
3785	
3786		rodata=		[KNL]
3787			on	Mark read-only kernel memory as read-only (default).
3788			off	Leave read-only kernel memory writable for debugging.
3789	
3790		rockchip.usb_uart
3791				Enable the uart passthrough on the designated usb port
3792				on Rockchip SoCs. When active, the signals of the
3793				debug-uart get routed to the D+ and D- pins of the usb
3794				port and the regular usb controller gets disabled.
3795	
3796		root=		[KNL] Root filesystem
3797				See name_to_dev_t comment in init/do_mounts.c.
3798	
3799		rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
3800				mount the root filesystem
3801	
3802		rootflags=	[KNL] Set root filesystem mount option string
3803	
3804		rootfstype=	[KNL] Set root filesystem type
3805	
3806		rootwait	[KNL] Wait (indefinitely) for root device to show up.
3807				Useful for devices that are detected asynchronously
3808				(e.g. USB and MMC devices).
3809	
3810		rproc_mem=nn[KMG][@address]
3811				[KNL,ARM,CMA] Remoteproc physical memory block.
3812				Memory area to be used by remote processor image,
3813				managed by CMA.
3814	
3815		rw		[KNL] Mount root device read-write on boot
3816	
3817		S		[KNL] Run init in single mode
3818	
3819		s390_iommu=	[HW,S390]
3820				Set s390 IOTLB flushing mode
3821			strict
3822				With strict flushing every unmap operation will result in
3823				an IOTLB flush. Default is lazy flushing before reuse,
3824				which is faster.
3825	
3826		sa1100ir	[NET]
3827				See drivers/net/irda/sa1100_ir.c.
3828	
3829		sbni=		[NET] Granch SBNI12 leased line adapter
3830	
3831		sched_debug	[KNL] Enables verbose scheduler debug messages.
3832	
3833		schedstats=	[KNL,X86] Enable or disable scheduled statistics.
3834				Allowed values are enable and disable. This feature
3835				incurs a small amount of overhead in the scheduler
3836				but is useful for debugging and performance tuning.
3837	
3838		skew_tick=	[KNL] Offset the periodic timer tick per cpu to mitigate
3839				xtime_lock contention on larger systems, and/or RCU lock
3840				contention on all systems with CONFIG_MAXSMP set.
3841				Format: { "0" | "1" }
3842				0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
3843				1 -- enable.
3844				Note: increases power consumption, thus should only be
3845				enabled if running jitter sensitive (HPC/RT) workloads.
3846	
3847		security=	[SECURITY] Choose a security module to enable at boot.
3848				If this boot parameter is not specified, only the first
3849				security module asking for security registration will be
3850				loaded. An invalid security module name will be treated
3851				as if no module has been chosen.
3852	
3853		selinux=	[SELINUX] Disable or enable SELinux at boot time.
3854				Format: { "0" | "1" }
3855				See security/selinux/Kconfig help text.
3856				0 -- disable.
3857				1 -- enable.
3858				Default value is set via kernel config option.
3859				If enabled at boot time, /selinux/disable can be used
3860				later to disable prior to initial policy load.
3861	
3862		apparmor=	[APPARMOR] Disable or enable AppArmor at boot time
3863				Format: { "0" | "1" }
3864				See security/apparmor/Kconfig help text
3865				0 -- disable.
3866				1 -- enable.
3867				Default value is set via kernel config option.
3868	
3869		serialnumber	[BUGS=X86-32]
3870	
3871		shapers=	[NET]
3872				Maximal number of shapers.
3873	
3874		simeth=		[IA-64]
3875		simscsi=
3876	
3877		slram=		[HW,MTD]
3878	
3879		slab_nomerge	[MM]
3880				Disable merging of slabs with similar size. May be
3881				necessary if there is some reason to distinguish
3882				allocs to different slabs, especially in hardened
3883				environments where the risk of heap overflows and
3884				layout control by attackers can usually be
3885				frustrated by disabling merging. This will reduce
3886				most of the exposure of a heap attack to a single
3887				cache (risks via metadata attacks are mostly
3888				unchanged). Debug options disable merging on their
3889				own.
3890				For more information see Documentation/vm/slub.txt.
3891	
3892		slab_max_order=	[MM, SLAB]
3893				Determines the maximum allowed order for slabs.
3894				A high setting may cause OOMs due to memory
3895				fragmentation.  Defaults to 1 for systems with
3896				more than 32MB of RAM, 0 otherwise.
3897	
3898		slub_debug[=options[,slabs]]	[MM, SLUB]
3899				Enabling slub_debug allows one to determine the
3900				culprit if slab objects become corrupted. Enabling
3901				slub_debug can create guard zones around objects and
3902				may poison objects when not in use. Also tracks the
3903				last alloc / free. For more information see
3904				Documentation/vm/slub.txt.
3905	
3906		slub_memcg_sysfs=	[MM, SLUB]
3907				Determines whether to enable sysfs directories for
3908				memory cgroup sub-caches. 1 to enable, 0 to disable.
3909				The default is determined by CONFIG_SLUB_MEMCG_SYSFS_ON.
3910				Enabling this can lead to a very high number of	debug
3911				directories and files being created under
3912				/sys/kernel/slub.
3913	
3914		slub_max_order= [MM, SLUB]
3915				Determines the maximum allowed order for slabs.
3916				A high setting may cause OOMs due to memory
3917				fragmentation. For more information see
3918				Documentation/vm/slub.txt.
3919	
3920		slub_min_objects=	[MM, SLUB]
3921				The minimum number of objects per slab. SLUB will
3922				increase the slab order up to slub_max_order to
3923				generate a sufficiently large slab able to contain
3924				the number of objects indicated. The higher the number
3925				of objects the smaller the overhead of tracking slabs
3926				and the less frequently locks need to be acquired.
3927				For more information see Documentation/vm/slub.txt.
3928	
3929		slub_min_order=	[MM, SLUB]
3930				Determines the minimum page order for slabs. Must be
3931				lower than slub_max_order.
3932				For more information see Documentation/vm/slub.txt.
3933	
3934		slub_nomerge	[MM, SLUB]
3935				Same with slab_nomerge. This is supported for legacy.
3936				See slab_nomerge for more information.
3937	
3938		smart2=		[HW]
3939				Format: <io1>[,<io2>[,...,<io8>]]
3940	
3941		smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
3942		smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
3943		smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
3944		smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
3945		smsc-ircc2.ircc_irq=	[HW] IRQ line
3946		smsc-ircc2.ircc_dma=	[HW] DMA channel
3947		smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
3948					0: Toshiba Satellite 1800 (GP data pin select)
3949					1: Fast pin select (default)
3950					2: ATC IRMode
3951	
3952		smt		[KNL,S390] Set the maximum number of threads (logical
3953				CPUs) to use per physical CPU on systems capable of
3954				symmetric multithreading (SMT). Will be capped to the
3955				actual hardware limit.
3956				Format: <integer>
3957				Default: -1 (no limit)
3958	
3959		softlockup_panic=
3960				[KNL] Should the soft-lockup detector generate panics.
3961				Format: <integer>
3962	
3963				A nonzero value instructs the soft-lockup detector
3964				to panic the machine when a soft-lockup occurs. This
3965				is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC
3966				which is the respective build-time switch to that
3967				functionality.
3968	
3969		softlockup_all_cpu_backtrace=
3970				[KNL] Should the soft-lockup detector generate
3971				backtraces on all cpus.
3972				Format: <integer>
3973	
3974		sonypi.*=	[HW] Sony Programmable I/O Control Device driver
3975				See Documentation/laptops/sonypi.txt
3976	
3977		spectre_v2=	[X86] Control mitigation of Spectre variant 2
3978				(indirect branch speculation) vulnerability.
3979	
3980				on   - unconditionally enable
3981				off  - unconditionally disable
3982				auto - kernel detects whether your CPU model is
3983				       vulnerable
3984	
3985				Selecting 'on' will, and 'auto' may, choose a
3986				mitigation method at run time according to the
3987				CPU, the available microcode, the setting of the
3988				CONFIG_RETPOLINE configuration option, and the
3989				compiler with which the kernel was built.
3990	
3991				Specific mitigations can also be selected manually:
3992	
3993				retpoline	  - replace indirect branches
3994				retpoline,generic - google's original retpoline
3995				retpoline,amd     - AMD-specific minimal thunk
3996	
3997				Not specifying this option is equivalent to
3998				spectre_v2=auto.
3999	
4000		spia_io_base=	[HW,MTD]
4001		spia_fio_base=
4002		spia_pedr=
4003		spia_peddr=
4004	
4005		srcutree.counter_wrap_check [KNL]
4006				Specifies how frequently to check for
4007				grace-period sequence counter wrap for the
4008				srcu_data structure's ->srcu_gp_seq_needed field.
4009				The greater the number of bits set in this kernel
4010				parameter, the less frequently counter wrap will
4011				be checked for.  Note that the bottom two bits
4012				are ignored.
4013	
4014		srcutree.exp_holdoff [KNL]
4015				Specifies how many nanoseconds must elapse
4016				since the end of the last SRCU grace period for
4017				a given srcu_struct until the next normal SRCU
4018				grace period will be considered for automatic
4019				expediting.  Set to zero to disable automatic
4020				expediting.
4021	
4022		stack_guard_gap=	[MM]
4023				override the default stack gap protection. The value
4024				is in page units and it defines how many pages prior
4025				to (for stacks growing down) resp. after (for stacks
4026				growing up) the main stack are reserved for no other
4027				mapping. Default value is 256 pages.
4028	
4029		stacktrace	[FTRACE]
4030				Enabled the stack tracer on boot up.
4031	
4032		stacktrace_filter=[function-list]
4033				[FTRACE] Limit the functions that the stack tracer
4034				will trace at boot up. function-list is a comma separated
4035				list of functions. This list can be changed at run
4036				time by the stack_trace_filter file in the debugfs
4037				tracing directory. Note, this enables stack tracing
4038				and the stacktrace above is not needed.
4039	
4040		sti=		[PARISC,HW]
4041				Format: <num>
4042				Set the STI (builtin display/keyboard on the HP-PARISC
4043				machines) console (graphic card) which should be used
4044				as the initial boot-console.
4045				See also comment in drivers/video/console/sticore.c.
4046	
4047		sti_font=	[HW]
4048				See comment in drivers/video/console/sticore.c.
4049	
4050		stifb=		[HW]
4051				Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
4052	
4053		sunrpc.min_resvport=
4054		sunrpc.max_resvport=
4055				[NFS,SUNRPC]
4056				SunRPC servers often require that client requests
4057				originate from a privileged port (i.e. a port in the
4058				range 0 < portnr < 1024).
4059				An administrator who wishes to reserve some of these
4060				ports for other uses may adjust the range that the
4061				kernel's sunrpc client considers to be privileged
4062				using these two parameters to set the minimum and
4063				maximum port values.
4064	
4065		sunrpc.svc_rpc_per_connection_limit=
4066				[NFS,SUNRPC]
4067				Limit the number of requests that the server will
4068				process in parallel from a single connection.
4069				The default value is 0 (no limit).
4070	
4071		sunrpc.pool_mode=
4072				[NFS]
4073				Control how the NFS server code allocates CPUs to
4074				service thread pools.  Depending on how many NICs
4075				you have and where their interrupts are bound, this
4076				option will affect which CPUs will do NFS serving.
4077				Note: this parameter cannot be changed while the
4078				NFS server is running.
4079	
4080				auto	    the server chooses an appropriate mode
4081					    automatically using heuristics
4082				global	    a single global pool contains all CPUs
4083				percpu	    one pool for each CPU
4084				pernode	    one pool for each NUMA node (equivalent
4085					    to global on non-NUMA machines)
4086	
4087		sunrpc.tcp_slot_table_entries=
4088		sunrpc.udp_slot_table_entries=
4089				[NFS,SUNRPC]
4090				Sets the upper limit on the number of simultaneous
4091				RPC calls that can be sent from the client to a
4092				server. Increasing these values may allow you to
4093				improve throughput, but will also increase the
4094				amount of memory reserved for use by the client.
4095	
4096		suspend.pm_test_delay=
4097				[SUSPEND]
4098				Sets the number of seconds to remain in a suspend test
4099				mode before resuming the system (see
4100				/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
4101				is set. Default value is 5.
4102	
4103		swapaccount=[0|1]
4104				[KNL] Enable accounting of swap in memory resource
4105				controller if no parameter or 1 is given or disable
4106				it if 0 is given (See Documentation/cgroup-v1/memory.txt)
4107	
4108		swiotlb=	[ARM,IA-64,PPC,MIPS,X86]
4109				Format: { <int> | force | noforce }
4110				<int> -- Number of I/O TLB slabs
4111				force -- force using of bounce buffers even if they
4112				         wouldn't be automatically used by the kernel
4113				noforce -- Never use bounce buffers (for debugging)
4114	
4115		switches=	[HW,M68k]
4116	
4117		sysfs.deprecated=0|1 [KNL]
4118				Enable/disable old style sysfs layout for old udev
4119				on older distributions. When this option is enabled
4120				very new udev will not work anymore. When this option
4121				is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
4122				in older udev will not work anymore.
4123				Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
4124				the kernel configuration.
4125	
4126		sysrq_always_enabled
4127				[KNL]
4128				Ignore sysrq setting - this boot parameter will
4129				neutralize any effect of /proc/sys/kernel/sysrq.
4130				Useful for debugging.
4131	
4132		tcpmhash_entries= [KNL,NET]
4133				Set the number of tcp_metrics_hash slots.
4134				Default value is 8192 or 16384 depending on total
4135				ram pages. This is used to specify the TCP metrics
4136				cache size. See Documentation/networking/ip-sysctl.txt
4137				"tcp_no_metrics_save" section for more details.
4138	
4139		tdfx=		[HW,DRM]
4140	
4141		test_suspend=	[SUSPEND][,N]
4142				Specify "mem" (for Suspend-to-RAM) or "standby" (for
4143				standby suspend) or "freeze" (for suspend type freeze)
4144				as the system sleep state during system startup with
4145				the optional capability to repeat N number of times.
4146				The system is woken from this state using a
4147				wakeup-capable RTC alarm.
4148	
4149		thash_entries=	[KNL,NET]
4150				Set number of hash buckets for TCP connection
4151	
4152		thermal.act=	[HW,ACPI]
4153				-1: disable all active trip points in all thermal zones
4154				<degrees C>: override all lowest active trip points
4155	
4156		thermal.crt=	[HW,ACPI]
4157				-1: disable all critical trip points in all thermal zones
4158				<degrees C>: override all critical trip points
4159	
4160		thermal.nocrt=	[HW,ACPI]
4161				Set to disable actions on ACPI thermal zone
4162				critical and hot trip points.
4163	
4164		thermal.off=	[HW,ACPI]
4165				1: disable ACPI thermal control
4166	
4167		thermal.psv=	[HW,ACPI]
4168				-1: disable all passive trip points
4169				<degrees C>: override all passive trip points to this
4170				value
4171	
4172		thermal.tzp=	[HW,ACPI]
4173				Specify global default ACPI thermal zone polling rate
4174				<deci-seconds>: poll all this frequency
4175				0: no polling (default)
4176	
4177		threadirqs	[KNL]
4178				Force threading of all interrupt handlers except those
4179				marked explicitly IRQF_NO_THREAD.
4180	
4181		tmem		[KNL,XEN]
4182				Enable the Transcendent memory driver if built-in.
4183	
4184		tmem.cleancache=0|1 [KNL, XEN]
4185				Default is on (1). Disable the usage of the cleancache
4186				API to send anonymous pages to the hypervisor.
4187	
4188		tmem.frontswap=0|1 [KNL, XEN]
4189				Default is on (1). Disable the usage of the frontswap
4190				API to send swap pages to the hypervisor. If disabled
4191				the selfballooning and selfshrinking are force disabled.
4192	
4193		tmem.selfballooning=0|1 [KNL, XEN]
4194				Default is on (1). Disable the driving of swap pages
4195				to the hypervisor.
4196	
4197		tmem.selfshrinking=0|1 [KNL, XEN]
4198				Default is on (1). Partial swapoff that immediately
4199				transfers pages from Xen hypervisor back to the
4200				kernel based on different criteria.
4201	
4202		topology=	[S390]
4203				Format: {off | on}
4204				Specify if the kernel should make use of the cpu
4205				topology information if the hardware supports this.
4206				The scheduler will make use of this information and
4207				e.g. base its process migration decisions on it.
4208				Default is on.
4209	
4210		topology_updates= [KNL, PPC, NUMA]
4211				Format: {off}
4212				Specify if the kernel should ignore (off)
4213				topology updates sent by the hypervisor to this
4214				LPAR.
4215	
4216		tp720=		[HW,PS2]
4217	
4218		tpm_suspend_pcr=[HW,TPM]
4219				Format: integer pcr id
4220				Specify that at suspend time, the tpm driver
4221				should extend the specified pcr with zeros,
4222				as a workaround for some chips which fail to
4223				flush the last written pcr on TPM_SaveState.
4224				This will guarantee that all the other pcrs
4225				are saved.
4226	
4227		trace_buf_size=nn[KMG]
4228				[FTRACE] will set tracing buffer size on each cpu.
4229	
4230		trace_event=[event-list]
4231				[FTRACE] Set and start specified trace events in order
4232				to facilitate early boot debugging. The event-list is a
4233				comma separated list of trace events to enable. See
4234				also Documentation/trace/events.txt
4235	
4236		trace_options=[option-list]
4237				[FTRACE] Enable or disable tracer options at boot.
4238				The option-list is a comma delimited list of options
4239				that can be enabled or disabled just as if you were
4240				to echo the option name into
4241	
4242				    /sys/kernel/debug/tracing/trace_options
4243	
4244				For example, to enable stacktrace option (to dump the
4245				stack trace of each event), add to the command line:
4246	
4247				      trace_options=stacktrace
4248	
4249				See also Documentation/trace/ftrace.txt "trace options"
4250				section.
4251	
4252		tp_printk[FTRACE]
4253				Have the tracepoints sent to printk as well as the
4254				tracing ring buffer. This is useful for early boot up
4255				where the system hangs or reboots and does not give the
4256				option for reading the tracing buffer or performing a
4257				ftrace_dump_on_oops.
4258	
4259				To turn off having tracepoints sent to printk,
4260				 echo 0 > /proc/sys/kernel/tracepoint_printk
4261				Note, echoing 1 into this file without the
4262				tracepoint_printk kernel cmdline option has no effect.
4263	
4264				** CAUTION **
4265	
4266				Having tracepoints sent to printk() and activating high
4267				frequency tracepoints such as irq or sched, can cause
4268				the system to live lock.
4269	
4270		traceoff_on_warning
4271				[FTRACE] enable this option to disable tracing when a
4272				warning is hit. This turns off "tracing_on". Tracing can
4273				be enabled again by echoing '1' into the "tracing_on"
4274				file located in /sys/kernel/debug/tracing/
4275	
4276				This option is useful, as it disables the trace before
4277				the WARNING dump is called, which prevents the trace to
4278				be filled with content caused by the warning output.
4279	
4280				This option can also be set at run time via the sysctl
4281				option:  kernel/traceoff_on_warning
4282	
4283		transparent_hugepage=
4284				[KNL]
4285				Format: [always|madvise|never]
4286				Can be used to control the default behavior of the system
4287				with respect to transparent hugepages.
4288				See Documentation/vm/transhuge.txt for more details.
4289	
4290		tsc=		Disable clocksource stability checks for TSC.
4291				Format: <string>
4292				[x86] reliable: mark tsc clocksource as reliable, this
4293				disables clocksource verification at runtime, as well
4294				as the stability checks done at bootup.	Used to enable
4295				high-resolution timer mode on older hardware, and in
4296				virtualized environment.
4297				[x86] noirqtime: Do not use TSC to do irq accounting.
4298				Used to run time disable IRQ_TIME_ACCOUNTING on any
4299				platforms where RDTSC is slow and this accounting
4300				can add overhead.
4301				[x86] unstable: mark the TSC clocksource as unstable, this
4302				marks the TSC unconditionally unstable at bootup and
4303				avoids any further wobbles once the TSC watchdog notices.
4304	
4305		turbografx.map[2|3]=	[HW,JOY]
4306				TurboGraFX parallel port interface
4307				Format:
4308				<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
4309				See also Documentation/input/devices/joystick-parport.rst
4310	
4311		udbg-immortal	[PPC] When debugging early kernel crashes that
4312				happen after console_init() and before a proper
4313				console driver takes over, this boot options might
4314				help "seeing" what's going on.
4315	
4316		uhash_entries=	[KNL,NET]
4317				Set number of hash buckets for UDP/UDP-Lite connections
4318	
4319		uhci-hcd.ignore_oc=
4320				[USB] Ignore overcurrent events (default N).
4321				Some badly-designed motherboards generate lots of
4322				bogus events, for ports that aren't wired to
4323				anything.  Set this parameter to avoid log spamming.
4324				Note that genuine overcurrent events won't be
4325				reported either.
4326	
4327		unknown_nmi_panic
4328				[X86] Cause panic on unknown NMI.
4329	
4330		usbcore.authorized_default=
4331				[USB] Default USB device authorization:
4332				(default -1 = authorized except for wireless USB,
4333				0 = not authorized, 1 = authorized)
4334	
4335		usbcore.autosuspend=
4336				[USB] The autosuspend time delay (in seconds) used
4337				for newly-detected USB devices (default 2).  This
4338				is the time required before an idle device will be
4339				autosuspended.  Devices for which the delay is set
4340				to a negative value won't be autosuspended at all.
4341	
4342		usbcore.usbfs_snoop=
4343				[USB] Set to log all usbfs traffic (default 0 = off).
4344	
4345		usbcore.usbfs_snoop_max=
4346				[USB] Maximum number of bytes to snoop in each URB
4347				(default = 65536).
4348	
4349		usbcore.blinkenlights=
4350				[USB] Set to cycle leds on hubs (default 0 = off).
4351	
4352		usbcore.old_scheme_first=
4353				[USB] Start with the old device initialization
4354				scheme (default 0 = off).
4355	
4356		usbcore.usbfs_memory_mb=
4357				[USB] Memory limit (in MB) for buffers allocated by
4358				usbfs (default = 16, 0 = max = 2047).
4359	
4360		usbcore.use_both_schemes=
4361				[USB] Try the other device initialization scheme
4362				if the first one fails (default 1 = enabled).
4363	
4364		usbcore.initial_descriptor_timeout=
4365				[USB] Specifies timeout for the initial 64-byte
4366	                        USB_REQ_GET_DESCRIPTOR request in milliseconds
4367				(default 5000 = 5.0 seconds).
4368	
4369		usbcore.nousb	[USB] Disable the USB subsystem
4370	
4371		usbhid.mousepoll=
4372				[USBHID] The interval which mice are to be polled at.
4373	
4374		usbhid.jspoll=
4375				[USBHID] The interval which joysticks are to be polled at.
4376	
4377		usb-storage.delay_use=
4378				[UMS] The delay in seconds before a new device is
4379				scanned for Logical Units (default 1).
4380	
4381		usb-storage.quirks=
4382				[UMS] A list of quirks entries to supplement or
4383				override the built-in unusual_devs list.  List
4384				entries are separated by commas.  Each entry has
4385				the form VID:PID:Flags where VID and PID are Vendor
4386				and Product ID values (4-digit hex numbers) and
4387				Flags is a set of characters, each corresponding
4388				to a common usb-storage quirk flag as follows:
4389					a = SANE_SENSE (collect more than 18 bytes
4390						of sense data);
4391					b = BAD_SENSE (don't collect more than 18
4392						bytes of sense data);
4393					c = FIX_CAPACITY (decrease the reported
4394						device capacity by one sector);
4395					d = NO_READ_DISC_INFO (don't use
4396						READ_DISC_INFO command);
4397					e = NO_READ_CAPACITY_16 (don't use
4398						READ_CAPACITY_16 command);
4399					f = NO_REPORT_OPCODES (don't use report opcodes
4400						command, uas only);
4401					g = MAX_SECTORS_240 (don't transfer more than
4402						240 sectors at a time, uas only);
4403					h = CAPACITY_HEURISTICS (decrease the
4404						reported device capacity by one
4405						sector if the number is odd);
4406					i = IGNORE_DEVICE (don't bind to this
4407						device);
4408					j = NO_REPORT_LUNS (don't use report luns
4409						command, uas only);
4410					l = NOT_LOCKABLE (don't try to lock and
4411						unlock ejectable media);
4412					m = MAX_SECTORS_64 (don't transfer more
4413						than 64 sectors = 32 KB at a time);
4414					n = INITIAL_READ10 (force a retry of the
4415						initial READ(10) command);
4416					o = CAPACITY_OK (accept the capacity
4417						reported by the device);
4418					p = WRITE_CACHE (the device cache is ON
4419						by default);
4420					r = IGNORE_RESIDUE (the device reports
4421						bogus residue values);
4422					s = SINGLE_LUN (the device has only one
4423						Logical Unit);
4424					t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
4425						commands, uas only);
4426					u = IGNORE_UAS (don't bind to the uas driver);
4427					w = NO_WP_DETECT (don't test whether the
4428						medium is write-protected).
4429					y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE
4430						even if the device claims no cache)
4431				Example: quirks=0419:aaf5:rl,0421:0433:rc
4432	
4433		user_debug=	[KNL,ARM]
4434				Format: <int>
4435				See arch/arm/Kconfig.debug help text.
4436					 1 - undefined instruction events
4437					 2 - system calls
4438					 4 - invalid data aborts
4439					 8 - SIGSEGV faults
4440					16 - SIGBUS faults
4441				Example: user_debug=31
4442	
4443		userpte=
4444				[X86] Flags controlling user PTE allocations.
4445	
4446					nohigh = do not allocate PTE pages in
4447						HIGHMEM regardless of setting
4448						of CONFIG_HIGHPTE.
4449	
4450		vdso=		[X86,SH]
4451				On X86_32, this is an alias for vdso32=.  Otherwise:
4452	
4453				vdso=1: enable VDSO (the default)
4454				vdso=0: disable VDSO mapping
4455	
4456		vdso32=		[X86] Control the 32-bit vDSO
4457				vdso32=1: enable 32-bit VDSO
4458				vdso32=0 or vdso32=2: disable 32-bit VDSO
4459	
4460				See the help text for CONFIG_COMPAT_VDSO for more
4461				details.  If CONFIG_COMPAT_VDSO is set, the default is
4462				vdso32=0; otherwise, the default is vdso32=1.
4463	
4464				For compatibility with older kernels, vdso32=2 is an
4465				alias for vdso32=0.
4466	
4467				Try vdso32=0 if you encounter an error that says:
4468				dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
4469	
4470		vector=		[IA-64,SMP]
4471				vector=percpu: enable percpu vector domain
4472	
4473		video=		[FB] Frame buffer configuration
4474				See Documentation/fb/modedb.txt.
4475	
4476		video.brightness_switch_enabled= [0,1]
4477				If set to 1, on receiving an ACPI notify event
4478				generated by hotkey, video driver will adjust brightness
4479				level and then send out the event to user space through
4480				the allocated input device; If set to 0, video driver
4481				will only send out the event without touching backlight
4482				brightness level.
4483				default: 1
4484	
4485		virtio_mmio.device=
4486				[VMMIO] Memory mapped virtio (platform) device.
4487	
4488					<size>@<baseaddr>:<irq>[:<id>]
4489				where:
4490					<size>     := size (can use standard suffixes
4491							like K, M and G)
4492					<baseaddr> := physical base address
4493					<irq>      := interrupt number (as passed to
4494							request_irq())
4495					<id>       := (optional) platform device id
4496				example:
4497					virtio_mmio.device=1K@0x100b0000:48:7
4498	
4499				Can be used multiple times for multiple devices.
4500	
4501		vga=		[BOOT,X86-32] Select a particular video mode
4502				See Documentation/x86/boot.txt and
4503				Documentation/svga.txt.
4504				Use vga=ask for menu.
4505				This is actually a boot loader parameter; the value is
4506				passed to the kernel using a special protocol.
4507	
4508		vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
4509				size of <nn>. This can be used to increase the
4510				minimum size (128MB on x86). It can also be used to
4511				decrease the size and leave more room for directly
4512				mapped kernel RAM.
4513	
4514		vmcp_cma=nn[MG]	[KNL,S390]
4515				Sets the memory size reserved for contiguous memory
4516				allocations for the vmcp device driver.
4517	
4518		vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
4519				Format: <command>
4520	
4521		vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
4522				Format: <command>
4523	
4524		vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
4525				Format: <command>
4526	
4527		vsyscall=	[X86-64]
4528				Controls the behavior of vsyscalls (i.e. calls to
4529				fixed addresses of 0xffffffffff600x00 from legacy
4530				code).  Most statically-linked binaries and older
4531				versions of glibc use these calls.  Because these
4532				functions are at fixed addresses, they make nice
4533				targets for exploits that can control RIP.
4534	
4535				emulate     [default] Vsyscalls turn into traps and are
4536				            emulated reasonably safely.
4537	
4538				native      Vsyscalls are native syscall instructions.
4539				            This is a little bit faster than trapping
4540				            and makes a few dynamic recompilers work
4541				            better than they would in emulation mode.
4542				            It also makes exploits much easier to write.
4543	
4544				none        Vsyscalls don't work at all.  This makes
4545				            them quite hard to use for exploits but
4546				            might break your system.
4547	
4548		vt.color=	[VT] Default text color.
4549				Format: 0xYX, X = foreground, Y = background.
4550				Default: 0x07 = light gray on black.
4551	
4552		vt.cur_default=	[VT] Default cursor shape.
4553				Format: 0xCCBBAA, where AA, BB, and CC are the same as
4554				the parameters of the <Esc>[?A;B;Cc escape sequence;
4555				see VGA-softcursor.txt. Default: 2 = underline.
4556	
4557		vt.default_blu=	[VT]
4558				Format: <blue0>,<blue1>,<blue2>,...,<blue15>
4559				Change the default blue palette of the console.
4560				This is a 16-member array composed of values
4561				ranging from 0-255.
4562	
4563		vt.default_grn=	[VT]
4564				Format: <green0>,<green1>,<green2>,...,<green15>
4565				Change the default green palette of the console.
4566				This is a 16-member array composed of values
4567				ranging from 0-255.
4568	
4569		vt.default_red=	[VT]
4570				Format: <red0>,<red1>,<red2>,...,<red15>
4571				Change the default red palette of the console.
4572				This is a 16-member array composed of values
4573				ranging from 0-255.
4574	
4575		vt.default_utf8=
4576				[VT]
4577				Format=<0|1>
4578				Set system-wide default UTF-8 mode for all tty's.
4579				Default is 1, i.e. UTF-8 mode is enabled for all
4580				newly opened terminals.
4581	
4582		vt.global_cursor_default=
4583				[VT]
4584				Format=<-1|0|1>
4585				Set system-wide default for whether a cursor
4586				is shown on new VTs. Default is -1,
4587				i.e. cursors will be created by default unless
4588				overridden by individual drivers. 0 will hide
4589				cursors, 1 will display them.
4590	
4591		vt.italic=	[VT] Default color for italic text; 0-15.
4592				Default: 2 = green.
4593	
4594		vt.underline=	[VT] Default color for underlined text; 0-15.
4595				Default: 3 = cyan.
4596	
4597		watchdog timers	[HW,WDT] For information on watchdog timers,
4598				see Documentation/watchdog/watchdog-parameters.txt
4599				or other driver-specific files in the
4600				Documentation/watchdog/ directory.
4601	
4602		workqueue.watchdog_thresh=
4603				If CONFIG_WQ_WATCHDOG is configured, workqueue can
4604				warn stall conditions and dump internal state to
4605				help debugging.  0 disables workqueue stall
4606				detection; otherwise, it's the stall threshold
4607				duration in seconds.  The default value is 30 and
4608				it can be updated at runtime by writing to the
4609				corresponding sysfs file.
4610	
4611		workqueue.disable_numa
4612				By default, all work items queued to unbound
4613				workqueues are affine to the NUMA nodes they're
4614				issued on, which results in better behavior in
4615				general.  If NUMA affinity needs to be disabled for
4616				whatever reason, this option can be used.  Note
4617				that this also can be controlled per-workqueue for
4618				workqueues visible under /sys/bus/workqueue/.
4619	
4620		workqueue.power_efficient
4621				Per-cpu workqueues are generally preferred because
4622				they show better performance thanks to cache
4623				locality; unfortunately, per-cpu workqueues tend to
4624				be more power hungry than unbound workqueues.
4625	
4626				Enabling this makes the per-cpu workqueues which
4627				were observed to contribute significantly to power
4628				consumption unbound, leading to measurably lower
4629				power usage at the cost of small performance
4630				overhead.
4631	
4632				The default value of this parameter is determined by
4633				the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
4634	
4635		workqueue.debug_force_rr_cpu
4636				Workqueue used to implicitly guarantee that work
4637				items queued without explicit CPU specified are put
4638				on the local CPU.  This guarantee is no longer true
4639				and while local CPU is still preferred work items
4640				may be put on foreign CPUs.  This debug option
4641				forces round-robin CPU selection to flush out
4642				usages which depend on the now broken guarantee.
4643				When enabled, memory and cache locality will be
4644				impacted.
4645	
4646		x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
4647				default x2apic cluster mode on platforms
4648				supporting x2apic.
4649	
4650		x86_intel_mid_timer= [X86-32,APBT]
4651				Choose timer option for x86 Intel MID platform.
4652				Two valid options are apbt timer only and lapic timer
4653				plus one apbt timer for broadcast timer.
4654				x86_intel_mid_timer=apbt_only | lapic_and_apbt
4655	
4656		xen_512gb_limit		[KNL,X86-64,XEN]
4657				Restricts the kernel running paravirtualized under Xen
4658				to use only up to 512 GB of RAM. The reason to do so is
4659				crash analysis tools and Xen tools for doing domain
4660				save/restore/migration must be enabled to handle larger
4661				domains.
4662	
4663		xen_emul_unplug=		[HW,X86,XEN]
4664				Unplug Xen emulated devices
4665				Format: [unplug0,][unplug1]
4666				ide-disks -- unplug primary master IDE devices
4667				aux-ide-disks -- unplug non-primary-master IDE devices
4668				nics -- unplug network devices
4669				all -- unplug all emulated devices (NICs and IDE disks)
4670				unnecessary -- unplugging emulated devices is
4671					unnecessary even if the host did not respond to
4672					the unplug protocol
4673				never -- do not unplug even if version check succeeds
4674	
4675		xen_nopvspin	[X86,XEN]
4676				Disables the ticketlock slowpath using Xen PV
4677				optimizations.
4678	
4679		xen_nopv	[X86]
4680				Disables the PV optimizations forcing the HVM guest to
4681				run as generic HVM guest with no PV drivers.
4682	
4683		xirc2ps_cs=	[NET,PCMCIA]
4684				Format:
4685				<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
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