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.rst, 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			{ vendor | video | native | none }
26			If set to vendor, prefer vendor-specific driver
27			(e.g. thinkpad_acpi, sony_acpi, etc.) instead
28			of the ACPI video.ko driver.
29			If set to video, use the ACPI video.ko driver.
30			If set to native, use the device's native backlight mode.
31			If set to none, disable the ACPI backlight interface.
32
33	acpi_force_32bit_fadt_addr
34			force FADT to use 32 bit addresses rather than the
35			64 bit X_* addresses. Some firmware have broken 64
36			bit addresses for force ACPI ignore these and use
37			the older legacy 32 bit addresses.
38
39	acpica_no_return_repair [HW, ACPI]
40			Disable AML predefined validation mechanism
41			This mechanism can repair the evaluation result to make
42			the return objects more ACPI specification compliant.
43			This option is useful for developers to identify the
44			root cause of an AML interpreter issue when the issue
45			has something to do with the repair mechanism.
46
47	acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
48	acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
49			Format: <int>
50			CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
51			debug output.  Bits in debug_layer correspond to a
52			_COMPONENT in an ACPI source file, e.g.,
53			    #define _COMPONENT ACPI_PCI_COMPONENT
54			Bits in debug_level correspond to a level in
55			ACPI_DEBUG_PRINT statements, e.g.,
56			    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
57			The debug_level mask defaults to "info".  See
58			Documentation/firmware-guide/acpi/debug.rst for more information about
59			debug layers and levels.
60
61			Enable processor driver info messages:
62			    acpi.debug_layer=0x20000000
63			Enable PCI/PCI interrupt routing info messages:
64			    acpi.debug_layer=0x400000
65			Enable AML "Debug" output, i.e., stores to the Debug
66			object while interpreting AML:
67			    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
68			Enable all messages related to ACPI hardware:
69			    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
70
71			Some values produce so much output that the system is
72			unusable.  The "log_buf_len" parameter may be useful
73			if you need to capture more output.
74
75	acpi_enforce_resources=	[ACPI]
76			{ strict | lax | no }
77			Check for resource conflicts between native drivers
78			and ACPI OperationRegions (SystemIO and SystemMemory
79			only). IO ports and memory declared in ACPI might be
80			used by the ACPI subsystem in arbitrary AML code and
81			can interfere with legacy drivers.
82			strict (default): access to resources claimed by ACPI
83			is denied; legacy drivers trying to access reserved
84			resources will fail to bind to device using them.
85			lax: access to resources claimed by ACPI is allowed;
86			legacy drivers trying to access reserved resources
87			will bind successfully but a warning message is logged.
88			no: ACPI OperationRegions are not marked as reserved,
89			no further checks are performed.
90
91	acpi_force_table_verification	[HW,ACPI]
92			Enable table checksum verification during early stage.
93			By default, this is disabled due to x86 early mapping
94			size limitation.
95
96	acpi_irq_balance [HW,ACPI]
97			ACPI will balance active IRQs
98			default in APIC mode
99
100	acpi_irq_nobalance [HW,ACPI]
101			ACPI will not move active IRQs (default)
102			default in PIC mode
103
104	acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
105			Format: <irq>,<irq>...
106
107	acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
108			use by PCI
109			Format: <irq>,<irq>...
110
111	acpi_mask_gpe=	[HW,ACPI]
112			Due to the existence of _Lxx/_Exx, some GPEs triggered
113			by unsupported hardware/firmware features can result in
114			GPE floodings that cannot be automatically disabled by
115			the GPE dispatcher.
116			This facility can be used to prevent such uncontrolled
117			GPE floodings.
118			Format: <byte>
119
120	acpi_no_auto_serialize	[HW,ACPI]
121			Disable auto-serialization of AML methods
122			AML control methods that contain the opcodes to create
123			named objects will be marked as "Serialized" by the
124			auto-serialization feature.
125			This feature is enabled by default.
126			This option allows to turn off the feature.
127
128	acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kdump
129			   kernels.
130
131	acpi_no_static_ssdt	[HW,ACPI]
132			Disable installation of static SSDTs at early boot time
133			By default, SSDTs contained in the RSDT/XSDT will be
134			installed automatically and they will appear under
135			/sys/firmware/acpi/tables.
136			This option turns off this feature.
137			Note that specifying this option does not affect
138			dynamic table installation which will install SSDT
139			tables to /sys/firmware/acpi/tables/dynamic.
140
141	acpi_no_watchdog	[HW,ACPI,WDT]
142			Ignore the ACPI-based watchdog interface (WDAT) and let
143			a native driver control the watchdog device instead.
144
145	acpi_rsdp=	[ACPI,EFI,KEXEC]
146			Pass the RSDP address to the kernel, mostly used
147			on machines running EFI runtime service to boot the
148			second kernel for kdump.
149
150	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
151			Format: To spoof as Windows 98: ="Microsoft Windows"
152
153	acpi_rev_override [ACPI] Override the _REV object to return 5 (instead
154			of 2 which is mandated by ACPI 6) as the supported ACPI
155			specification revision (when using this switch, it may
156			be necessary to carry out a cold reboot _twice_ in a
157			row to make it take effect on the platform firmware).
158
159	acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
160			acpi_osi="string1"	# add string1
161			acpi_osi="!string2"	# remove string2
162			acpi_osi=!*		# remove all strings
163			acpi_osi=!		# disable all built-in OS vendor
164						  strings
165			acpi_osi=!!		# enable all built-in OS vendor
166						  strings
167			acpi_osi=		# disable all strings
168
169			'acpi_osi=!' can be used in combination with single or
170			multiple 'acpi_osi="string1"' to support specific OS
171			vendor string(s).  Note that such command can only
172			affect the default state of the OS vendor strings, thus
173			it cannot affect the default state of the feature group
174			strings and the current state of the OS vendor strings,
175			specifying it multiple times through kernel command line
176			is meaningless.  This command is useful when one do not
177			care about the state of the feature group strings which
178			should be controlled by the OSPM.
179			Examples:
180			  1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
181			     to 'acpi_osi="Windows 2000" acpi_osi=!', they all
182			     can make '_OSI("Windows 2000")' TRUE.
183
184			'acpi_osi=' cannot be used in combination with other
185			'acpi_osi=' command lines, the _OSI method will not
186			exist in the ACPI namespace.  NOTE that such command can
187			only affect the _OSI support state, thus specifying it
188			multiple times through kernel command line is also
189			meaningless.
190			Examples:
191			  1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
192			     FALSE.
193
194			'acpi_osi=!*' can be used in combination with single or
195			multiple 'acpi_osi="string1"' to support specific
196			string(s).  Note that such command can affect the
197			current state of both the OS vendor strings and the
198			feature group strings, thus specifying it multiple times
199			through kernel command line is meaningful.  But it may
200			still not able to affect the final state of a string if
201			there are quirks related to this string.  This command
202			is useful when one want to control the state of the
203			feature group strings to debug BIOS issues related to
204			the OSPM features.
205			Examples:
206			  1. 'acpi_osi="Module Device" acpi_osi=!*' can make
207			     '_OSI("Module Device")' FALSE.
208			  2. 'acpi_osi=!* acpi_osi="Module Device"' can make
209			     '_OSI("Module Device")' TRUE.
210			  3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
211			     equivalent to
212			     'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
213			     and
214			     'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
215			     they all will make '_OSI("Windows 2000")' TRUE.
216
217	acpi_pm_good	[X86]
218			Override the pmtimer bug detection: force the kernel
219			to assume that this machine's pmtimer latches its value
220			and always returns good values.
221
222	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
223			Format: { level | edge | high | low }
224
225	acpi_skip_timer_override [HW,ACPI]
226			Recognize and ignore IRQ0/pin2 Interrupt Override.
227			For broken nForce2 BIOS resulting in XT-PIC timer.
228
229	acpi_sleep=	[HW,ACPI] Sleep options
230			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
231				  old_ordering, nonvs, sci_force_enable, nobl }
232			See Documentation/power/video.rst for information on
233			s3_bios and s3_mode.
234			s3_beep is for debugging; it makes the PC's speaker beep
235			as soon as the kernel's real-mode entry point is called.
236			s4_nohwsig prevents ACPI hardware signature from being
237			used during resume from hibernation.
238			old_ordering causes the ACPI 1.0 ordering of the _PTS
239			control method, with respect to putting devices into
240			low power states, to be enforced (the ACPI 2.0 ordering
241			of _PTS is used by default).
242			nonvs prevents the kernel from saving/restoring the
243			ACPI NVS memory during suspend/hibernation and resume.
244			sci_force_enable causes the kernel to set SCI_EN directly
245			on resume from S1/S3 (which is against the ACPI spec,
246			but some broken systems don't work without it).
247			nobl causes the internal blacklist of systems known to
248			behave incorrectly in some ways with respect to system
249			suspend and resume to be ignored (use wisely).
250
251	acpi_use_timer_override [HW,ACPI]
252			Use timer override. For some broken Nvidia NF5 boards
253			that require a timer override, but don't have HPET
254
255	add_efi_memmap	[EFI; X86] Include EFI memory map in
256			kernel's map of available physical RAM.
257
258	agp=		[AGP]
259			{ off | try_unsupported }
260			off: disable AGP support
261			try_unsupported: try to drive unsupported chipsets
262				(may crash computer or cause data corruption)
263
264	ALSA		[HW,ALSA]
265			See Documentation/sound/alsa-configuration.rst
266
267	alignment=	[KNL,ARM]
268			Allow the default userspace alignment fault handler
269			behaviour to be specified.  Bit 0 enables warnings,
270			bit 1 enables fixups, and bit 2 sends a segfault.
271
272	align_va_addr=	[X86-64]
273			Align virtual addresses by clearing slice [14:12] when
274			allocating a VMA at process creation time. This option
275			gives you up to 3% performance improvement on AMD F15h
276			machines (where it is enabled by default) for a
277			CPU-intensive style benchmark, and it can vary highly in
278			a microbenchmark depending on workload and compiler.
279
280			32: only for 32-bit processes
281			64: only for 64-bit processes
282			on: enable for both 32- and 64-bit processes
283			off: disable for both 32- and 64-bit processes
284
285	alloc_snapshot	[FTRACE]
286			Allocate the ftrace snapshot buffer on boot up when the
287			main buffer is allocated. This is handy if debugging
288			and you need to use tracing_snapshot() on boot up, and
289			do not want to use tracing_snapshot_alloc() as it needs
290			to be done where GFP_KERNEL allocations are allowed.
291
292	amd_iommu=	[HW,X86-64]
293			Pass parameters to the AMD IOMMU driver in the system.
294			Possible values are:
295			fullflush - enable flushing of IO/TLB entries when
296				    they are unmapped. Otherwise they are
297				    flushed before they will be reused, which
298				    is a lot of faster
299			off	  - do not initialize any AMD IOMMU found in
300				    the system
301			force_isolation - Force device isolation for all
302					  devices. The IOMMU driver is not
303					  allowed anymore to lift isolation
304					  requirements as needed. This option
305					  does not override iommu=pt
306
307	amd_iommu_dump=	[HW,X86-64]
308			Enable AMD IOMMU driver option to dump the ACPI table
309			for AMD IOMMU. With this option enabled, AMD IOMMU
310			driver will print ACPI tables for AMD IOMMU during
311			IOMMU initialization.
312
313	amd_iommu_intr=	[HW,X86-64]
314			Specifies one of the following AMD IOMMU interrupt
315			remapping modes:
316			legacy     - Use legacy interrupt remapping mode.
317			vapic      - Use virtual APIC mode, which allows IOMMU
318			             to inject interrupts directly into guest.
319			             This mode requires kvm-amd.avic=1.
320			             (Default when IOMMU HW support is present.)
321
322	amijoy.map=	[HW,JOY] Amiga joystick support
323			Map of devices attached to JOY0DAT and JOY1DAT
324			Format: <a>,<b>
325			See also Documentation/input/joydev/joystick.rst
326
327	analog.map=	[HW,JOY] Analog joystick and gamepad support
328			Specifies type or capabilities of an analog joystick
329			connected to one of 16 gameports
330			Format: <type1>,<type2>,..<type16>
331
332	apc=		[HW,SPARC]
333			Power management functions (SPARCstation-4/5 + deriv.)
334			Format: noidle
335			Disable APC CPU standby support. SPARCstation-Fox does
336			not play well with APC CPU idle - disable it if you have
337			APC and your system crashes randomly.
338
339	apic=		[APIC,X86] Advanced Programmable Interrupt Controller
340			Change the output verbosity while booting
341			Format: { quiet (default) | verbose | debug }
342			Change the amount of debugging information output
343			when initialising the APIC and IO-APIC components.
344			For X86-32, this can also be used to specify an APIC
345			driver name.
346			Format: apic=driver_name
347			Examples: apic=bigsmp
348
349	apic_extnmi=	[APIC,X86] External NMI delivery setting
350			Format: { bsp (default) | all | none }
351			bsp:  External NMI is delivered only to CPU 0
352			all:  External NMIs are broadcast to all CPUs as a
353			      backup of CPU 0
354			none: External NMI is masked for all CPUs. This is
355			      useful so that a dump capture kernel won't be
356			      shot down by NMI
357
358	autoconf=	[IPV6]
359			See Documentation/networking/ipv6.rst.
360
361	show_lapic=	[APIC,X86] Advanced Programmable Interrupt Controller
362			Limit apic dumping. The parameter defines the maximal
363			number of local apics being dumped. Also it is possible
364			to set it to "all" by meaning -- no limit here.
365			Format: { 1 (default) | 2 | ... | all }.
366			The parameter valid if only apic=debug or
367			apic=verbose is specified.
368			Example: apic=debug show_lapic=all
369
370	apm=		[APM] Advanced Power Management
371			See header of arch/x86/kernel/apm_32.c.
372
373	arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
374			Format: <io>,<irq>,<nodeID>
375
376	ataflop=	[HW,M68k]
377
378	atarimouse=	[HW,MOUSE] Atari Mouse
379
380	atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
381			EzKey and similar keyboards
382
383	atkbd.reset=	[HW] Reset keyboard during initialization
384
385	atkbd.set=	[HW] Select keyboard code set
386			Format: <int> (2 = AT (default), 3 = PS/2)
387
388	atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
389			keyboards
390
391	atkbd.softraw=	[HW] Choose between synthetic and real raw mode
392			Format: <bool> (0 = real, 1 = synthetic (default))
393
394	atkbd.softrepeat= [HW]
395			Use software keyboard repeat
396
397	audit=		[KNL] Enable the audit sub-system
398			Format: { "0" | "1" | "off" | "on" }
399			0 | off - kernel audit is disabled and can not be
400			    enabled until the next reboot
401			unset - kernel audit is initialized but disabled and
402			    will be fully enabled by the userspace auditd.
403			1 | on - kernel audit is initialized and partially
404			    enabled, storing at most audit_backlog_limit
405			    messages in RAM until it is fully enabled by the
406			    userspace auditd.
407			Default: unset
408
409	audit_backlog_limit= [KNL] Set the audit queue size limit.
410			Format: <int> (must be >=0)
411			Default: 64
412
413	bau=		[X86_UV] Enable the BAU on SGI UV.  The default
414			behavior is to disable the BAU (i.e. bau=0).
415			Format: { "0" | "1" }
416			0 - Disable the BAU.
417			1 - Enable the BAU.
418			unset - Disable the BAU.
419
420	baycom_epp=	[HW,AX25]
421			Format: <io>,<mode>
422
423	baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
424			Format: <io>,<mode>
425			See header of drivers/net/hamradio/baycom_par.c.
426
427	baycom_ser_fdx=	[HW,AX25]
428			BayCom Serial Port AX.25 Modem (Full Duplex Mode)
429			Format: <io>,<irq>,<mode>[,<baud>]
430			See header of drivers/net/hamradio/baycom_ser_fdx.c.
431
432	baycom_ser_hdx=	[HW,AX25]
433			BayCom Serial Port AX.25 Modem (Half Duplex Mode)
434			Format: <io>,<irq>,<mode>
435			See header of drivers/net/hamradio/baycom_ser_hdx.c.
436
437	blkdevparts=	Manual partition parsing of block device(s) for
438			embedded devices based on command line input.
439			See Documentation/block/cmdline-partition.rst
440
441	boot_delay=	Milliseconds to delay each printk during boot.
442			Values larger than 10 seconds (10000) are changed to
443			no delay (0).
444			Format: integer
445
446	bootconfig	[KNL]
447			Extended command line options can be added to an initrd
448			and this will cause the kernel to look for it.
449
450			See Documentation/admin-guide/bootconfig.rst
451
452	bert_disable	[ACPI]
453			Disable BERT OS support on buggy BIOSes.
454
455	bgrt_disable	[ACPI][X86]
456			Disable BGRT to avoid flickering OEM logo.
457
458	bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
459	bttv.radio=	Most important insmod options are available as
460			kernel args too.
461	bttv.pll=	See Documentation/admin-guide/media/bttv.rst
462	bttv.tuner=
463
464	bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
465			firmware feature for flushing multiple hpte entries
466			at a time.
467
468	c101=		[NET] Moxa C101 synchronous serial card
469
470	cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
471			Sometimes CPU hardware bugs make them report the cache
472			size incorrectly. The kernel will attempt work arounds
473			to fix known problems, but for some CPUs it is not
474			possible to determine what the correct size should be.
475			This option provides an override for these situations.
476
477	carrier_timeout=
478			[NET] Specifies amount of time (in seconds) that
479			the kernel should wait for a network carrier. By default
480			it waits 120 seconds.
481
482	ca_keys=	[KEYS] This parameter identifies a specific key(s) on
483			the system trusted keyring to be used for certificate
484			trust validation.
485			format: { id:<keyid> | builtin }
486
487	cca=		[MIPS] Override the kernel pages' cache coherency
488			algorithm.  Accepted values range from 0 to 7
489			inclusive. See arch/mips/include/asm/pgtable-bits.h
490			for platform specific values (SB1, Loongson3 and
491			others).
492
493	ccw_timeout_log	[S390]
494			See Documentation/s390/common_io.rst for details.
495
496	cgroup_disable=	[KNL] Disable a particular controller
497			Format: {name of the controller(s) to disable}
498			The effects of cgroup_disable=foo are:
499			- foo isn't auto-mounted if you mount all cgroups in
500			  a single hierarchy
501			- foo isn't visible as an individually mountable
502			  subsystem
503			{Currently only "memory" controller deal with this and
504			cut the overhead, others just disable the usage. So
505			only cgroup_disable=memory is actually worthy}
506
507	cgroup_no_v1=	[KNL] Disable cgroup controllers and named hierarchies in v1
508			Format: { { controller | "all" | "named" }
509			          [,{ controller | "all" | "named" }...] }
510			Like cgroup_disable, but only applies to cgroup v1;
511			the blacklisted controllers remain available in cgroup2.
512			"all" blacklists all controllers and "named" disables
513			named mounts. Specifying both "all" and "named" disables
514			all v1 hierarchies.
515
516	cgroup.memory=	[KNL] Pass options to the cgroup memory controller.
517			Format: <string>
518			nosocket -- Disable socket memory accounting.
519			nokmem -- Disable kernel memory accounting.
520
521	checkreqprot	[SELINUX] Set initial checkreqprot flag value.
522			Format: { "0" | "1" }
523			See security/selinux/Kconfig help text.
524			0 -- check protection applied by kernel (includes
525				any implied execute protection).
526			1 -- check protection requested by application.
527			Default value is set via a kernel config option.
528			Value can be changed at runtime via
529				/sys/fs/selinux/checkreqprot.
530			Setting checkreqprot to 1 is deprecated.
531
532	cio_ignore=	[S390]
533			See Documentation/s390/common_io.rst for details.
534	clk_ignore_unused
535			[CLK]
536			Prevents the clock framework from automatically gating
537			clocks that have not been explicitly enabled by a Linux
538			device driver but are enabled in hardware at reset or
539			by the bootloader/firmware. Note that this does not
540			force such clocks to be always-on nor does it reserve
541			those clocks in any way. This parameter is useful for
542			debug and development, but should not be needed on a
543			platform with proper driver support.  For more
544			information, see Documentation/driver-api/clk.rst.
545
546	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
547			[Deprecated]
548			Forces specified clocksource (if available) to be used
549			when calculating gettimeofday(). If specified
550			clocksource is not available, it defaults to PIT.
551			Format: { pit | tsc | cyclone | pmtmr }
552
553	clocksource=	Override the default clocksource
554			Format: <string>
555			Override the default clocksource and use the clocksource
556			with the name specified.
557			Some clocksource names to choose from, depending on
558			the platform:
559			[all] jiffies (this is the base, fallback clocksource)
560			[ACPI] acpi_pm
561			[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
562				pxa_timer,timer3,32k_counter,timer0_1
563			[X86-32] pit,hpet,tsc;
564				scx200_hrt on Geode; cyclone on IBM x440
565			[MIPS] MIPS
566			[PARISC] cr16
567			[S390] tod
568			[SH] SuperH
569			[SPARC64] tick
570			[X86-64] hpet,tsc
571
572	clocksource.arm_arch_timer.evtstrm=
573			[ARM,ARM64]
574			Format: <bool>
575			Enable/disable the eventstream feature of the ARM
576			architected timer so that code using WFE-based polling
577			loops can be debugged more effectively on production
578			systems.
579
580	clearcpuid=BITNUM[,BITNUM...] [X86]
581			Disable CPUID feature X for the kernel. See
582			arch/x86/include/asm/cpufeatures.h for the valid bit
583			numbers. Note the Linux specific bits are not necessarily
584			stable over kernel options, but the vendor specific
585			ones should be.
586			Also note that user programs calling CPUID directly
587			or using the feature without checking anything
588			will still see it. This just prevents it from
589			being used by the kernel or shown in /proc/cpuinfo.
590			Also note the kernel might malfunction if you disable
591			some critical bits.
592
593	cma=nn[MG]@[start[MG][-end[MG]]]
594			[KNL,CMA]
595			Sets the size of kernel global memory area for
596			contiguous memory allocations and optionally the
597			placement constraint by the physical address range of
598			memory allocations. A value of 0 disables CMA
599			altogether. For more information, see
600			kernel/dma/contiguous.c
601
602	cma_pernuma=nn[MG]
603			[ARM64,KNL]
604			Sets the size of kernel per-numa memory area for
605			contiguous memory allocations. A value of 0 disables
606			per-numa CMA altogether. And If this option is not
607			specificed, the default value is 0.
608			With per-numa CMA enabled, DMA users on node nid will
609			first try to allocate buffer from the pernuma area
610			which is located in node nid, if the allocation fails,
611			they will fallback to the global default memory area.
612
613	cmo_free_hint=	[PPC] Format: { yes | no }
614			Specify whether pages are marked as being inactive
615			when they are freed.  This is used in CMO environments
616			to determine OS memory pressure for page stealing by
617			a hypervisor.
618			Default: yes
619
620	coherent_pool=nn[KMG]	[ARM,KNL]
621			Sets the size of memory pool for coherent, atomic dma
622			allocations, by default set to 256K.
623
624	com20020=	[HW,NET] ARCnet - COM20020 chipset
625			Format:
626			<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
627
628	com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
629			Format: <io>[,<irq>]
630
631	com90xx=	[HW,NET]
632			ARCnet - COM90xx chipset (memory-mapped buffers)
633			Format: <io>[,<irq>[,<memstart>]]
634
635	condev=		[HW,S390] console device
636	conmode=
637
638	console=	[KNL] Output console device and options.
639
640		tty<n>	Use the virtual console device <n>.
641
642		ttyS<n>[,options]
643		ttyUSB0[,options]
644			Use the specified serial port.  The options are of
645			the form "bbbbpnf", where "bbbb" is the baud rate,
646			"p" is parity ("n", "o", or "e"), "n" is number of
647			bits, and "f" is flow control ("r" for RTS or
648			omit it).  Default is "9600n8".
649
650			See Documentation/admin-guide/serial-console.rst for more
651			information.  See
652			Documentation/networking/netconsole.rst for an
653			alternative.
654
655		uart[8250],io,<addr>[,options]
656		uart[8250],mmio,<addr>[,options]
657		uart[8250],mmio16,<addr>[,options]
658		uart[8250],mmio32,<addr>[,options]
659		uart[8250],0x<addr>[,options]
660			Start an early, polled-mode console on the 8250/16550
661			UART at the specified I/O port or MMIO address,
662			switching to the matching ttyS device later.
663			MMIO inter-register address stride is either 8-bit
664			(mmio), 16-bit (mmio16), or 32-bit (mmio32).
665			If none of [io|mmio|mmio16|mmio32], <addr> is assumed
666			to be equivalent to 'mmio'. 'options' are specified in
667			the same format described for ttyS above; if unspecified,
668			the h/w is not re-initialized.
669
670		hvc<n>	Use the hypervisor console device <n>. This is for
671			both Xen and PowerPC hypervisors.
672
673		If the device connected to the port is not a TTY but a braille
674		device, prepend "brl," before the device type, for instance
675			console=brl,ttyS0
676		For now, only VisioBraille is supported.
677
678	console_msg_format=
679			[KNL] Change console messages format
680		default
681			By default we print messages on consoles in
682			"[time stamp] text\n" format (time stamp may not be
683			printed, depending on CONFIG_PRINTK_TIME or
684			`printk_time' param).
685		syslog
686			Switch to syslog format: "<%u>[time stamp] text\n"
687			IOW, each message will have a facility and loglevel
688			prefix. The format is similar to one used by syslog()
689			syscall, or to executing "dmesg -S --raw" or to reading
690			from /proc/kmsg.
691
692	consoleblank=	[KNL] The console blank (screen saver) timeout in
693			seconds. A value of 0 disables the blank timer.
694			Defaults to 0.
695
696	coredump_filter=
697			[KNL] Change the default value for
698			/proc/<pid>/coredump_filter.
699			See also Documentation/filesystems/proc.rst.
700
701	coresight_cpu_debug.enable
702			[ARM,ARM64]
703			Format: <bool>
704			Enable/disable the CPU sampling based debugging.
705			0: default value, disable debugging
706			1: enable debugging at boot time
707
708	cpuidle.off=1	[CPU_IDLE]
709			disable the cpuidle sub-system
710
711	cpuidle.governor=
712			[CPU_IDLE] Name of the cpuidle governor to use.
713
714	cpufreq.off=1	[CPU_FREQ]
715			disable the cpufreq sub-system
716
717	cpufreq.default_governor=
718			[CPU_FREQ] Name of the default cpufreq governor or
719			policy to use. This governor must be registered in the
720			kernel before the cpufreq driver probes.
721
722	cpu_init_udelay=N
723			[X86] Delay for N microsec between assert and de-assert
724			of APIC INIT to start processors.  This delay occurs
725			on every CPU online, such as boot, and resume from suspend.
726			Default: 10000
727
728	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
729			Format:
730			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
731
732	crashkernel=size[KMG][@offset[KMG]]
733			[KNL] Using kexec, Linux can switch to a 'crash kernel'
734			upon panic. This parameter reserves the physical
735			memory region [offset, offset + size] for that kernel
736			image. If '@offset' is omitted, then a suitable offset
737			is selected automatically.
738			[KNL, X86-64] Select a region under 4G first, and
739			fall back to reserve region above 4G when '@offset'
740			hasn't been specified.
741			See Documentation/admin-guide/kdump/kdump.rst for further details.
742
743	crashkernel=range1:size1[,range2:size2,...][@offset]
744			[KNL] Same as above, but depends on the memory
745			in the running system. The syntax of range is
746			start-[end] where start and end are both
747			a memory unit (amount[KMG]). See also
748			Documentation/admin-guide/kdump/kdump.rst for an example.
749
750	crashkernel=size[KMG],high
751			[KNL, X86-64] range could be above 4G. Allow kernel
752			to allocate physical memory region from top, so could
753			be above 4G if system have more than 4G ram installed.
754			Otherwise memory region will be allocated below 4G, if
755			available.
756			It will be ignored if crashkernel=X is specified.
757	crashkernel=size[KMG],low
758			[KNL, X86-64] range under 4G. When crashkernel=X,high
759			is passed, kernel could allocate physical memory region
760			above 4G, that cause second kernel crash on system
761			that require some amount of low memory, e.g. swiotlb
762			requires at least 64M+32K low memory, also enough extra
763			low memory is needed to make sure DMA buffers for 32-bit
764			devices won't run out. Kernel would try to allocate at
765			at least 256M below 4G automatically.
766			This one let user to specify own low range under 4G
767			for second kernel instead.
768			0: to disable low allocation.
769			It will be ignored when crashkernel=X,high is not used
770			or memory reserved is below 4G.
771
772	cryptomgr.notests
773			[KNL] Disable crypto self-tests
774
775	cs89x0_dma=	[HW,NET]
776			Format: <dma>
777
778	cs89x0_media=	[HW,NET]
779			Format: { rj45 | aui | bnc }
780
781	dasd=		[HW,NET]
782			See header of drivers/s390/block/dasd_devmap.c.
783
784	db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
785			(one device per port)
786			Format: <port#>,<type>
787			See also Documentation/input/devices/joystick-parport.rst
788
789	ddebug_query=	[KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
790			time. See
791			Documentation/admin-guide/dynamic-debug-howto.rst for
792			details.  Deprecated, see dyndbg.
793
794	debug		[KNL] Enable kernel debugging (events log level).
795
796	debug_boot_weak_hash
797			[KNL] Enable printing [hashed] pointers early in the
798			boot sequence.  If enabled, we use a weak hash instead
799			of siphash to hash pointers.  Use this option if you are
800			seeing instances of '(___ptrval___)') and need to see a
801			value (hashed pointer) instead. Cryptographically
802			insecure, please do not use on production kernels.
803
804	debug_locks_verbose=
805			[KNL] verbose self-tests
806			Format=<0|1>
807			Print debugging info while doing the locking API
808			self-tests.
809			We default to 0 (no extra messages), setting it to
810			1 will print _a lot_ more information - normally
811			only useful to kernel developers.
812
813	debug_objects	[KNL] Enable object debugging
814
815	no_debug_objects
816			[KNL] Disable object debugging
817
818	debug_guardpage_minorder=
819			[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
820			parameter allows control of the order of pages that will
821			be intentionally kept free (and hence protected) by the
822			buddy allocator. Bigger value increase the probability
823			of catching random memory corruption, but reduce the
824			amount of memory for normal system use. The maximum
825			possible value is MAX_ORDER/2.  Setting this parameter
826			to 1 or 2 should be enough to identify most random
827			memory corruption problems caused by bugs in kernel or
828			driver code when a CPU writes to (or reads from) a
829			random memory location. Note that there exists a class
830			of memory corruptions problems caused by buggy H/W or
831			F/W or by drivers badly programing DMA (basically when
832			memory is written at bus level and the CPU MMU is
833			bypassed) which are not detectable by
834			CONFIG_DEBUG_PAGEALLOC, hence this option will not help
835			tracking down these problems.
836
837	debug_pagealloc=
838			[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this parameter
839			enables the feature at boot time. By default, it is
840			disabled and the system will work mostly the same as a
841			kernel built without CONFIG_DEBUG_PAGEALLOC.
842			Note: to get most of debug_pagealloc error reports, it's
843			useful to also enable the page_owner functionality.
844			on: enable the feature
845
846	debugfs=    	[KNL] This parameter enables what is exposed to userspace
847			and debugfs internal clients.
848			Format: { on, no-mount, off }
849			on: 	All functions are enabled.
850			no-mount:
851				Filesystem is not registered but kernel clients can
852			        access APIs and a crashkernel can be used to read
853				its content. There is nothing to mount.
854			off: 	Filesystem is not registered and clients
855			        get a -EPERM as result when trying to register files
856				or directories within debugfs.
857				This is equivalent of the runtime functionality if
858				debugfs was not enabled in the kernel at all.
859			Default value is set in build-time with a kernel configuration.
860
861	debugpat	[X86] Enable PAT debugging
862
863	decnet.addr=	[HW,NET]
864			Format: <area>[,<node>]
865			See also Documentation/networking/decnet.rst.
866
867	default_hugepagesz=
868			[HW] The size of the default HugeTLB page. This is
869			the size represented by the legacy /proc/ hugepages
870			APIs.  In addition, this is the default hugetlb size
871			used for shmget(), mmap() and mounting hugetlbfs
872			filesystems.  If not specified, defaults to the
873			architecture's default huge page size.  Huge page
874			sizes are architecture dependent.  See also
875			Documentation/admin-guide/mm/hugetlbpage.rst.
876			Format: size[KMG]
877
878	deferred_probe_timeout=
879			[KNL] Debugging option to set a timeout in seconds for
880			deferred probe to give up waiting on dependencies to
881			probe. Only specific dependencies (subsystems or
882			drivers) that have opted in will be ignored. A timeout of 0
883			will timeout at the end of initcalls. This option will also
884			dump out devices still on the deferred probe list after
885			retrying.
886
887	dfltcc=		[HW,S390]
888			Format: { on | off | def_only | inf_only | always }
889			on:       s390 zlib hardware support for compression on
890			          level 1 and decompression (default)
891			off:      No s390 zlib hardware support
892			def_only: s390 zlib hardware support for deflate
893			          only (compression on level 1)
894			inf_only: s390 zlib hardware support for inflate
895			          only (decompression)
896			always:   Same as 'on' but ignores the selected compression
897			          level always using hardware support (used for debugging)
898
899	dhash_entries=	[KNL]
900			Set number of hash buckets for dentry cache.
901
902	disable_1tb_segments [PPC]
903			Disables the use of 1TB hash page table segments. This
904			causes the kernel to fall back to 256MB segments which
905			can be useful when debugging issues that require an SLB
906			miss to occur.
907
908	stress_slb	[PPC]
909			Limits the number of kernel SLB entries, and flushes
910			them frequently to increase the rate of SLB faults
911			on kernel addresses.
912
913	disable=	[IPV6]
914			See Documentation/networking/ipv6.rst.
915
916	hardened_usercopy=
917                        [KNL] Under CONFIG_HARDENED_USERCOPY, whether
918                        hardening is enabled for this boot. Hardened
919                        usercopy checking is used to protect the kernel
920                        from reading or writing beyond known memory
921                        allocation boundaries as a proactive defense
922                        against bounds-checking flaws in the kernel's
923                        copy_to_user()/copy_from_user() interface.
924                on      Perform hardened usercopy checks (default).
925                off     Disable hardened usercopy checks.
926
927	disable_radix	[PPC]
928			Disable RADIX MMU mode on POWER9
929
930	radix_hcall_invalidate=on  [PPC/PSERIES]
931			Disable RADIX GTSE feature and use hcall for TLB
932			invalidate.
933
934	disable_tlbie	[PPC]
935			Disable TLBIE instruction. Currently does not work
936			with KVM, with HASH MMU, or with coherent accelerators.
937
938	disable_cpu_apicid= [X86,APIC,SMP]
939			Format: <int>
940			The number of initial APIC ID for the
941			corresponding CPU to be disabled at boot,
942			mostly used for the kdump 2nd kernel to
943			disable BSP to wake up multiple CPUs without
944			causing system reset or hang due to sending
945			INIT from AP to BSP.
946
947	perf_v4_pmi=	[X86,INTEL]
948			Format: <bool>
949			Disable Intel PMU counter freezing feature.
950			The feature only exists starting from
951			Arch Perfmon v4 (Skylake and newer).
952
953	disable_ddw	[PPC/PSERIES]
954			Disable Dynamic DMA Window support. Use this
955			to workaround buggy firmware.
956
957	disable_ipv6=	[IPV6]
958			See Documentation/networking/ipv6.rst.
959
960	disable_mtrr_cleanup [X86]
961			The kernel tries to adjust MTRR layout from continuous
962			to discrete, to make X server driver able to add WB
963			entry later. This parameter disables that.
964
965	disable_mtrr_trim [X86, Intel and AMD only]
966			By default the kernel will trim any uncacheable
967			memory out of your available memory pool based on
968			MTRR settings.  This parameter disables that behavior,
969			possibly causing your machine to run very slowly.
970
971	disable_timer_pin_1 [X86]
972			Disable PIN 1 of APIC timer
973			Can be useful to work around chipset bugs.
974
975	dis_ucode_ldr	[X86] Disable the microcode loader.
976
977	dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
978			this option disables the debugging code at boot.
979
980	dma_debug_entries=<number>
981			This option allows to tune the number of preallocated
982			entries for DMA-API debugging code. One entry is
983			required per DMA-API allocation. Use this if the
984			DMA-API debugging code disables itself because the
985			architectural default is too low.
986
987	dma_debug_driver=<driver_name>
988			With this option the DMA-API debugging driver
989			filter feature can be enabled at boot time. Just
990			pass the driver to filter for as the parameter.
991			The filter can be disabled or changed to another
992			driver later using sysfs.
993
994	driver_async_probe=  [KNL]
995			List of driver names to be probed asynchronously.
996			Format: <driver_name1>,<driver_name2>...
997
998	drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
999			Broken monitors, graphic adapters, KVMs and EDIDless
1000			panels may send no or incorrect EDID data sets.
1001			This parameter allows to specify an EDID data sets
1002			in the /lib/firmware directory that are used instead.
1003			Generic built-in EDID data sets are used, if one of
1004			edid/1024x768.bin, edid/1280x1024.bin,
1005			edid/1680x1050.bin, or edid/1920x1080.bin is given
1006			and no file with the same name exists. Details and
1007			instructions how to build your own EDID data are
1008			available in Documentation/admin-guide/edid.rst. An EDID
1009			data set will only be used for a particular connector,
1010			if its name and a colon are prepended to the EDID
1011			name. Each connector may use a unique EDID data
1012			set by separating the files with a comma.  An EDID
1013			data set with no connector name will be used for
1014			any connectors not explicitly specified.
1015
1016	dscc4.setup=	[NET]
1017
1018	dt_cpu_ftrs=	[PPC]
1019			Format: {"off" | "known"}
1020			Control how the dt_cpu_ftrs device-tree binding is
1021			used for CPU feature discovery and setup (if it
1022			exists).
1023			off: Do not use it, fall back to legacy cpu table.
1024			known: Do not pass through unknown features to guests
1025			or userspace, only those that the kernel is aware of.
1026
1027	dump_apple_properties	[X86]
1028			Dump name and content of EFI device properties on
1029			x86 Macs.  Useful for driver authors to determine
1030			what data is available or for reverse-engineering.
1031
1032	dyndbg[="val"]		[KNL,DYNAMIC_DEBUG]
1033	<module>.dyndbg[="val"]
1034			Enable debug messages at boot time.  See
1035			Documentation/admin-guide/dynamic-debug-howto.rst
1036			for details.
1037
1038	nopku		[X86] Disable Memory Protection Keys CPU feature found
1039			in some Intel CPUs.
1040
1041	<module>.async_probe [KNL]
1042			Enable asynchronous probe on this module.
1043
1044	early_ioremap_debug [KNL]
1045			Enable debug messages in early_ioremap support. This
1046			is useful for tracking down temporary early mappings
1047			which are not unmapped.
1048
1049	earlycon=	[KNL] Output early console device and options.
1050
1051			When used with no options, the early console is
1052			determined by stdout-path property in device tree's
1053			chosen node or the ACPI SPCR table if supported by
1054			the platform.
1055
1056		cdns,<addr>[,options]
1057			Start an early, polled-mode console on a Cadence
1058			(xuartps) serial port at the specified address. Only
1059			supported option is baud rate. If baud rate is not
1060			specified, the serial port must already be setup and
1061			configured.
1062
1063		uart[8250],io,<addr>[,options]
1064		uart[8250],mmio,<addr>[,options]
1065		uart[8250],mmio32,<addr>[,options]
1066		uart[8250],mmio32be,<addr>[,options]
1067		uart[8250],0x<addr>[,options]
1068			Start an early, polled-mode console on the 8250/16550
1069			UART at the specified I/O port or MMIO address.
1070			MMIO inter-register address stride is either 8-bit
1071			(mmio) or 32-bit (mmio32 or mmio32be).
1072			If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
1073			to be equivalent to 'mmio'. 'options' are specified
1074			in the same format described for "console=ttyS<n>"; if
1075			unspecified, the h/w is not initialized.
1076
1077		pl011,<addr>
1078		pl011,mmio32,<addr>
1079			Start an early, polled-mode console on a pl011 serial
1080			port at the specified address. The pl011 serial port
1081			must already be setup and configured. Options are not
1082			yet supported.  If 'mmio32' is specified, then only
1083			the driver will use only 32-bit accessors to read/write
1084			the device registers.
1085
1086		meson,<addr>
1087			Start an early, polled-mode console on a meson serial
1088			port at the specified address. The serial port must
1089			already be setup and configured. Options are not yet
1090			supported.
1091
1092		msm_serial,<addr>
1093			Start an early, polled-mode console on an msm serial
1094			port at the specified address. The serial port
1095			must already be setup and configured. Options are not
1096			yet supported.
1097
1098		msm_serial_dm,<addr>
1099			Start an early, polled-mode console on an msm serial
1100			dm port at the specified address. The serial port
1101			must already be setup and configured. Options are not
1102			yet supported.
1103
1104		owl,<addr>
1105			Start an early, polled-mode console on a serial port
1106			of an Actions Semi SoC, such as S500 or S900, at the
1107			specified address. The serial port must already be
1108			setup and configured. Options are not yet supported.
1109
1110		rda,<addr>
1111			Start an early, polled-mode console on a serial port
1112			of an RDA Micro SoC, such as RDA8810PL, at the
1113			specified address. The serial port must already be
1114			setup and configured. Options are not yet supported.
1115
1116		sbi
1117			Use RISC-V SBI (Supervisor Binary Interface) for early
1118			console.
1119
1120		smh	Use ARM semihosting calls for early console.
1121
1122		s3c2410,<addr>
1123		s3c2412,<addr>
1124		s3c2440,<addr>
1125		s3c6400,<addr>
1126		s5pv210,<addr>
1127		exynos4210,<addr>
1128			Use early console provided by serial driver available
1129			on Samsung SoCs, requires selecting proper type and
1130			a correct base address of the selected UART port. The
1131			serial port must already be setup and configured.
1132			Options are not yet supported.
1133
1134		lantiq,<addr>
1135			Start an early, polled-mode console on a lantiq serial
1136			(lqasc) port at the specified address. The serial port
1137			must already be setup and configured. Options are not
1138			yet supported.
1139
1140		lpuart,<addr>
1141		lpuart32,<addr>
1142			Use early console provided by Freescale LP UART driver
1143			found on Freescale Vybrid and QorIQ LS1021A processors.
1144			A valid base address must be provided, and the serial
1145			port must already be setup and configured.
1146
1147		ec_imx21,<addr>
1148		ec_imx6q,<addr>
1149			Start an early, polled-mode, output-only console on the
1150			Freescale i.MX UART at the specified address. The UART
1151			must already be setup and configured.
1152
1153		ar3700_uart,<addr>
1154			Start an early, polled-mode console on the
1155			Armada 3700 serial port at the specified
1156			address. The serial port must already be setup
1157			and configured. Options are not yet supported.
1158
1159		qcom_geni,<addr>
1160			Start an early, polled-mode console on a Qualcomm
1161			Generic Interface (GENI) based serial port at the
1162			specified address. The serial port must already be
1163			setup and configured. Options are not yet supported.
1164
1165		efifb,[options]
1166			Start an early, unaccelerated console on the EFI
1167			memory mapped framebuffer (if available). On cache
1168			coherent non-x86 systems that use system memory for
1169			the framebuffer, pass the 'ram' option so that it is
1170			mapped with the correct attributes.
1171
1172		linflex,<addr>
1173			Use early console provided by Freescale LINFlexD UART
1174			serial driver for NXP S32V234 SoCs. A valid base
1175			address must be provided, and the serial port must
1176			already be setup and configured.
1177
1178	earlyprintk=	[X86,SH,ARM,M68k,S390]
1179			earlyprintk=vga
1180			earlyprintk=sclp
1181			earlyprintk=xen
1182			earlyprintk=serial[,ttySn[,baudrate]]
1183			earlyprintk=serial[,0x...[,baudrate]]
1184			earlyprintk=ttySn[,baudrate]
1185			earlyprintk=dbgp[debugController#]
1186			earlyprintk=pciserial[,force],bus:device.function[,baudrate]
1187			earlyprintk=xdbc[xhciController#]
1188
1189			earlyprintk is useful when the kernel crashes before
1190			the normal console is initialized. It is not enabled by
1191			default because it has some cosmetic problems.
1192
1193			Append ",keep" to not disable it when the real console
1194			takes over.
1195
1196			Only one of vga, efi, serial, or usb debug port can
1197			be used at a time.
1198
1199			Currently only ttyS0 and ttyS1 may be specified by
1200			name.  Other I/O ports may be explicitly specified
1201			on some architectures (x86 and arm at least) by
1202			replacing ttySn with an I/O port address, like this:
1203				earlyprintk=serial,0x1008,115200
1204			You can find the port for a given device in
1205			/proc/tty/driver/serial:
1206				2: uart:ST16650V2 port:00001008 irq:18 ...
1207
1208			Interaction with the standard serial driver is not
1209			very good.
1210
1211			The VGA and EFI output is eventually overwritten by
1212			the real console.
1213
1214			The xen output can only be used by Xen PV guests.
1215
1216			The sclp output can only be used on s390.
1217
1218			The optional "force" to "pciserial" enables use of a
1219			PCI device even when its classcode is not of the
1220			UART class.
1221
1222	edac_report=	[HW,EDAC] Control how to report EDAC event
1223			Format: {"on" | "off" | "force"}
1224			on: enable EDAC to report H/W event. May be overridden
1225			by other higher priority error reporting module.
1226			off: disable H/W event reporting through EDAC.
1227			force: enforce the use of EDAC to report H/W event.
1228			default: on.
1229
1230	ekgdboc=	[X86,KGDB] Allow early kernel console debugging
1231			ekgdboc=kbd
1232
1233			This is designed to be used in conjunction with
1234			the boot argument: earlyprintk=vga
1235
1236			This parameter works in place of the kgdboc parameter
1237			but can only be used if the backing tty is available
1238			very early in the boot process. For early debugging
1239			via a serial port see kgdboc_earlycon instead.
1240
1241	edd=		[EDD]
1242			Format: {"off" | "on" | "skip[mbr]"}
1243
1244	efi=		[EFI]
1245			Format: { "debug", "disable_early_pci_dma",
1246				  "nochunk", "noruntime", "nosoftreserve",
1247				  "novamap", "no_disable_early_pci_dma" }
1248			debug: enable misc debug output.
1249			disable_early_pci_dma: disable the busmaster bit on all
1250			PCI bridges while in the EFI boot stub.
1251			nochunk: disable reading files in "chunks" in the EFI
1252			boot stub, as chunking can cause problems with some
1253			firmware implementations.
1254			noruntime : disable EFI runtime services support
1255			nosoftreserve: The EFI_MEMORY_SP (Specific Purpose)
1256			attribute may cause the kernel to reserve the
1257			memory range for a memory mapping driver to
1258			claim. Specify efi=nosoftreserve to disable this
1259			reservation and treat the memory by its base type
1260			(i.e. EFI_CONVENTIONAL_MEMORY / "System RAM").
1261			novamap: do not call SetVirtualAddressMap().
1262			no_disable_early_pci_dma: Leave the busmaster bit set
1263			on all PCI bridges while in the EFI boot stub
1264
1265	efi_no_storage_paranoia [EFI; X86]
1266			Using this parameter you can use more than 50% of
1267			your efi variable storage. Use this parameter only if
1268			you are really sure that your UEFI does sane gc and
1269			fulfills the spec otherwise your board may brick.
1270
1271	efi_fake_mem=	nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86]
1272			Add arbitrary attribute to specific memory range by
1273			updating original EFI memory map.
1274			Region of memory which aa attribute is added to is
1275			from ss to ss+nn.
1276
1277			If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
1278			is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
1279			attribute is added to range 0x100000000-0x180000000 and
1280			0x10a0000000-0x1120000000.
1281
1282			If efi_fake_mem=8G@9G:0x40000 is specified, the
1283			EFI_MEMORY_SP(0x40000) attribute is added to
1284			range 0x240000000-0x43fffffff.
1285
1286			Using this parameter you can do debugging of EFI memmap
1287			related features. For example, you can do debugging of
1288			Address Range Mirroring feature even if your box
1289			doesn't support it, or mark specific memory as
1290			"soft reserved".
1291
1292	efivar_ssdt=	[EFI; X86] Name of an EFI variable that contains an SSDT
1293			that is to be dynamically loaded by Linux. If there are
1294			multiple variables with the same name but with different
1295			vendor GUIDs, all of them will be loaded. See
1296			Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1297
1298
1299	eisa_irq_edge=	[PARISC,HW]
1300			See header of drivers/parisc/eisa.c.
1301
1302	elanfreq=	[X86-32]
1303			See comment before function elanfreq_setup() in
1304			arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1305
1306	elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
1307			Specifies physical address of start of kernel core
1308			image elf header and optionally the size. Generally
1309			kexec loader will pass this option to capture kernel.
1310			See Documentation/admin-guide/kdump/kdump.rst for details.
1311
1312	enable_mtrr_cleanup [X86]
1313			The kernel tries to adjust MTRR layout from continuous
1314			to discrete, to make X server driver able to add WB
1315			entry later. This parameter enables that.
1316
1317	enable_timer_pin_1 [X86]
1318			Enable PIN 1 of APIC timer
1319			Can be useful to work around chipset bugs
1320			(in particular on some ATI chipsets).
1321			The kernel tries to set a reasonable default.
1322
1323	enforcing	[SELINUX] Set initial enforcing status.
1324			Format: {"0" | "1"}
1325			See security/selinux/Kconfig help text.
1326			0 -- permissive (log only, no denials).
1327			1 -- enforcing (deny and log).
1328			Default value is 0.
1329			Value can be changed at runtime via
1330			/sys/fs/selinux/enforce.
1331
1332	erst_disable	[ACPI]
1333			Disable Error Record Serialization Table (ERST)
1334			support.
1335
1336	ether=		[HW,NET] Ethernet cards parameters
1337			This option is obsoleted by the "netdev=" option, which
1338			has equivalent usage. See its documentation for details.
1339
1340	evm=		[EVM]
1341			Format: { "fix" }
1342			Permit 'security.evm' to be updated regardless of
1343			current integrity status.
1344
1345	failslab=
1346	fail_usercopy=
1347	fail_page_alloc=
1348	fail_make_request=[KNL]
1349			General fault injection mechanism.
1350			Format: <interval>,<probability>,<space>,<times>
1351			See also Documentation/fault-injection/.
1352
1353	fb_tunnels=	[NET]
1354			Format: { initns | none }
1355			See Documentation/admin-guide/sysctl/net.rst for
1356			fb_tunnels_only_for_init_ns
1357
1358	floppy=		[HW]
1359			See Documentation/admin-guide/blockdev/floppy.rst.
1360
1361	force_pal_cache_flush
1362			[IA-64] Avoid check_sal_cache_flush which may hang on
1363			buggy SAL_CACHE_FLUSH implementations. Using this
1364			parameter will force ia64_sal_cache_flush to call
1365			ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
1366
1367	forcepae	[X86-32]
1368			Forcefully enable Physical Address Extension (PAE).
1369			Many Pentium M systems disable PAE but may have a
1370			functionally usable PAE implementation.
1371			Warning: use of this parameter will taint the kernel
1372			and may cause unknown problems.
1373
1374	ftrace=[tracer]
1375			[FTRACE] will set and start the specified tracer
1376			as early as possible in order to facilitate early
1377			boot debugging.
1378
1379	ftrace_dump_on_oops[=orig_cpu]
1380			[FTRACE] will dump the trace buffers on oops.
1381			If no parameter is passed, ftrace will dump
1382			buffers of all CPUs, but if you pass orig_cpu, it will
1383			dump only the buffer of the CPU that triggered the
1384			oops.
1385
1386	ftrace_filter=[function-list]
1387			[FTRACE] Limit the functions traced by the function
1388			tracer at boot up. function-list is a comma separated
1389			list of functions. This list can be changed at run
1390			time by the set_ftrace_filter file in the debugfs
1391			tracing directory.
1392
1393	ftrace_notrace=[function-list]
1394			[FTRACE] Do not trace the functions specified in
1395			function-list. This list can be changed at run time
1396			by the set_ftrace_notrace file in the debugfs
1397			tracing directory.
1398
1399	ftrace_graph_filter=[function-list]
1400			[FTRACE] Limit the top level callers functions traced
1401			by the function graph tracer at boot up.
1402			function-list is a comma separated list of functions
1403			that can be changed at run time by the
1404			set_graph_function file in the debugfs tracing directory.
1405
1406	ftrace_graph_notrace=[function-list]
1407			[FTRACE] Do not trace from the functions specified in
1408			function-list.  This list is a comma separated list of
1409			functions that can be changed at run time by the
1410			set_graph_notrace file in the debugfs tracing directory.
1411
1412	ftrace_graph_max_depth=<uint>
1413			[FTRACE] Used with the function graph tracer. This is
1414			the max depth it will trace into a function. This value
1415			can be changed at run time by the max_graph_depth file
1416			in the tracefs tracing directory. default: 0 (no limit)
1417
1418	fw_devlink=	[KNL] Create device links between consumer and supplier
1419			devices by scanning the firmware to infer the
1420			consumer/supplier relationships. This feature is
1421			especially useful when drivers are loaded as modules as
1422			it ensures proper ordering of tasks like device probing
1423			(suppliers first, then consumers), supplier boot state
1424			clean up (only after all consumers have probed),
1425			suspend/resume & runtime PM (consumers first, then
1426			suppliers).
1427			Format: { off | permissive | on | rpm }
1428			off --	Don't create device links from firmware info.
1429			permissive -- Create device links from firmware info
1430				but use it only for ordering boot state clean
1431				up (sync_state() calls).
1432			on -- 	Create device links from firmware info and use it
1433				to enforce probe and suspend/resume ordering.
1434			rpm --	Like "on", but also use to order runtime PM.
1435
1436	gamecon.map[2|3]=
1437			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
1438			support via parallel port (up to 5 devices per port)
1439			Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1440			See also Documentation/input/devices/joystick-parport.rst
1441
1442	gamma=		[HW,DRM]
1443
1444	gart_fix_e820=	[X86-64] disable the fix e820 for K8 GART
1445			Format: off | on
1446			default: on
1447
1448	gcov_persist=	[GCOV] When non-zero (default), profiling data for
1449			kernel modules is saved and remains accessible via
1450			debugfs, even when the module is unloaded/reloaded.
1451			When zero, profiling data is discarded and associated
1452			debugfs files are removed at module unload time.
1453
1454	goldfish	[X86] Enable the goldfish android emulator platform.
1455			Don't use this when you are not running on the
1456			android emulator
1457
1458	gpt		[EFI] Forces disk with valid GPT signature but
1459			invalid Protective MBR to be treated as GPT. If the
1460			primary GPT is corrupted, it enables the backup/alternate
1461			GPT to be used instead.
1462
1463	grcan.enable0=	[HW] Configuration of physical interface 0. Determines
1464			the "Enable 0" bit of the configuration register.
1465			Format: 0 | 1
1466			Default: 0
1467	grcan.enable1=	[HW] Configuration of physical interface 1. Determines
1468			the "Enable 0" bit of the configuration register.
1469			Format: 0 | 1
1470			Default: 0
1471	grcan.select=	[HW] Select which physical interface to use.
1472			Format: 0 | 1
1473			Default: 0
1474	grcan.txsize=	[HW] Sets the size of the tx buffer.
1475			Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
1476			Default: 1024
1477	grcan.rxsize=	[HW] Sets the size of the rx buffer.
1478			Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
1479			Default: 1024
1480
1481	gpio-mockup.gpio_mockup_ranges
1482			[HW] Sets the ranges of gpiochip of for this device.
1483			Format: <start1>,<end1>,<start2>,<end2>...
1484
1485	hardlockup_all_cpu_backtrace=
1486			[KNL] Should the hard-lockup detector generate
1487			backtraces on all cpus.
1488			Format: 0 | 1
1489
1490	hashdist=	[KNL,NUMA] Large hashes allocated during boot
1491			are distributed across NUMA nodes.  Defaults on
1492			for 64-bit NUMA, off otherwise.
1493			Format: 0 | 1 (for off | on)
1494
1495	hcl=		[IA-64] SGI's Hardware Graph compatibility layer
1496
1497	hd=		[EIDE] (E)IDE hard drive subsystem geometry
1498			Format: <cyl>,<head>,<sect>
1499
1500	hest_disable	[ACPI]
1501			Disable Hardware Error Source Table (HEST) support;
1502			corresponding firmware-first mode error processing
1503			logic will be disabled.
1504
1505	highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
1506			size of <nn>. This works even on boxes that have no
1507			highmem otherwise. This also works to reduce highmem
1508			size on bigger boxes.
1509
1510	highres=	[KNL] Enable/disable high resolution timer mode.
1511			Valid parameters: "on", "off"
1512			Default: "on"
1513
1514	hlt		[BUGS=ARM,SH]
1515
1516	hpet=		[X86-32,HPET] option to control HPET usage
1517			Format: { enable (default) | disable | force |
1518				verbose }
1519			disable: disable HPET and use PIT instead
1520			force: allow force enabled of undocumented chips (ICH4,
1521				VIA, nVidia)
1522			verbose: show contents of HPET registers during setup
1523
1524	hpet_mmap=	[X86, HPET_MMAP] Allow userspace to mmap HPET
1525			registers.  Default set by CONFIG_HPET_MMAP_DEFAULT.
1526
1527	hugetlb_cma=	[HW] The size of a cma area used for allocation
1528			of gigantic hugepages.
1529			Format: nn[KMGTPE]
1530
1531			Reserve a cma area of given size and allocate gigantic
1532			hugepages using the cma allocator. If enabled, the
1533			boot-time allocation of gigantic hugepages is skipped.
1534
1535	hugepages=	[HW] Number of HugeTLB pages to allocate at boot.
1536			If this follows hugepagesz (below), it specifies
1537			the number of pages of hugepagesz to be allocated.
1538			If this is the first HugeTLB parameter on the command
1539			line, it specifies the number of pages to allocate for
1540			the default huge page size.  See also
1541			Documentation/admin-guide/mm/hugetlbpage.rst.
1542			Format: <integer>
1543
1544	hugepagesz=
1545			[HW] The size of the HugeTLB pages.  This is used in
1546			conjunction with hugepages (above) to allocate huge
1547			pages of a specific size at boot.  The pair
1548			hugepagesz=X hugepages=Y can be specified once for
1549			each supported huge page size. Huge page sizes are
1550			architecture dependent.  See also
1551			Documentation/admin-guide/mm/hugetlbpage.rst.
1552			Format: size[KMG]
1553
1554	hung_task_panic=
1555			[KNL] Should the hung task detector generate panics.
1556			Format: 0 | 1
1557
1558			A value of 1 instructs the kernel to panic when a
1559			hung task is detected. The default value is controlled
1560			by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1561			option. The value selected by this boot parameter can
1562			be changed later by the kernel.hung_task_panic sysctl.
1563
1564	hvc_iucv=	[S390]	Number of z/VM IUCV hypervisor console (HVC)
1565				terminal devices. Valid values: 0..8
1566	hvc_iucv_allow=	[S390]	Comma-separated list of z/VM user IDs.
1567				If specified, z/VM IUCV HVC accepts connections
1568				from listed z/VM user IDs only.
1569
1570	hv_nopvspin	[X86,HYPER_V] Disables the paravirt spinlock optimizations
1571				      which allow the hypervisor to 'idle' the
1572				      guest on lock contention.
1573
1574	keep_bootcon	[KNL]
1575			Do not unregister boot console at start. This is only
1576			useful for debugging when something happens in the window
1577			between unregistering the boot console and initializing
1578			the real console.
1579
1580	i2c_bus=	[HW]	Override the default board specific I2C bus speed
1581				or register an additional I2C bus that is not
1582				registered from board initialization code.
1583				Format:
1584				<bus_id>,<clkrate>
1585
1586	i8042.debug	[HW] Toggle i8042 debug mode
1587	i8042.unmask_kbd_data
1588			[HW] Enable printing of interrupt data from the KBD port
1589			     (disabled by default, and as a pre-condition
1590			     requires that i8042.debug=1 be enabled)
1591	i8042.direct	[HW] Put keyboard port into non-translated mode
1592	i8042.dumbkbd	[HW] Pretend that controller can only read data from
1593			     keyboard and cannot control its state
1594			     (Don't attempt to blink the leds)
1595	i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
1596	i8042.nokbd	[HW] Don't check/create keyboard port
1597	i8042.noloop	[HW] Disable the AUX Loopback command while probing
1598			     for the AUX port
1599	i8042.nomux	[HW] Don't check presence of an active multiplexing
1600			     controller
1601	i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1602			     controllers
1603	i8042.notimeout	[HW] Ignore timeout condition signalled by controller
1604	i8042.reset	[HW] Reset the controller during init, cleanup and
1605			     suspend-to-ram transitions, only during s2r
1606			     transitions, or never reset
1607			Format: { 1 | Y | y | 0 | N | n }
1608			1, Y, y: always reset controller
1609			0, N, n: don't ever reset controller
1610			Default: only on s2r transitions on x86; most other
1611			architectures force reset to be always executed
1612	i8042.unlock	[HW] Unlock (ignore) the keylock
1613	i8042.kbdreset	[HW] Reset device connected to KBD port
1614
1615	i810=		[HW,DRM]
1616
1617	i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
1618			indicates that the driver is running on unsupported
1619			hardware.
1620	i8k.force	[HW] Activate i8k driver even if SMM BIOS signature
1621			does not match list of supported models.
1622	i8k.power_status
1623			[HW] Report power status in /proc/i8k
1624			(disabled by default)
1625	i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN
1626			capability is set.
1627
1628	i915.invert_brightness=
1629			[DRM] Invert the sense of the variable that is used to
1630			set the brightness of the panel backlight. Normally a
1631			brightness value of 0 indicates backlight switched off,
1632			and the maximum of the brightness value sets the backlight
1633			to maximum brightness. If this parameter is set to 0
1634			(default) and the machine requires it, or this parameter
1635			is set to 1, a brightness value of 0 sets the backlight
1636			to maximum brightness, and the maximum of the brightness
1637			value switches the backlight off.
1638			-1 -- never invert brightness
1639			 0 -- machine default
1640			 1 -- force brightness inversion
1641
1642	icn=		[HW,ISDN]
1643			Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1644
1645	ide-core.nodma=	[HW] (E)IDE subsystem
1646			Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1647			.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1648			.cdrom .chs .ignore_cable are additional options
1649			See Documentation/ide/ide.rst.
1650
1651	ide-generic.probe-mask= [HW] (E)IDE subsystem
1652			Format: <int>
1653			Probe mask for legacy ISA IDE ports.  Depending on
1654			platform up to 6 ports are supported, enabled by
1655			setting corresponding bits in the mask to 1.  The
1656			default value is 0x0, which has a special meaning.
1657			On systems that have PCI, it triggers scanning the
1658			PCI bus for the first and the second port, which
1659			are then probed.  On systems without PCI the value
1660			of 0x0 enables probing the two first ports as if it
1661			was 0x3.
1662
1663	ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1664			Claim all unknown PCI IDE storage controllers.
1665
1666	idle=		[X86]
1667			Format: idle=poll, idle=halt, idle=nomwait
1668			Poll forces a polling idle loop that can slightly
1669			improve the performance of waking up a idle CPU, but
1670			will use a lot of power and make the system run hot.
1671			Not recommended.
1672			idle=halt: Halt is forced to be used for CPU idle.
1673			In such case C2/C3 won't be used again.
1674			idle=nomwait: Disable mwait for CPU C-states
1675
1676	ieee754=	[MIPS] Select IEEE Std 754 conformance mode
1677			Format: { strict | legacy | 2008 | relaxed }
1678			Default: strict
1679
1680			Choose which programs will be accepted for execution
1681			based on the IEEE 754 NaN encoding(s) supported by
1682			the FPU and the NaN encoding requested with the value
1683			of an ELF file header flag individually set by each
1684			binary.  Hardware implementations are permitted to
1685			support either or both of the legacy and the 2008 NaN
1686			encoding mode.
1687
1688			Available settings are as follows:
1689			strict	accept binaries that request a NaN encoding
1690				supported by the FPU
1691			legacy	only accept legacy-NaN binaries, if supported
1692				by the FPU
1693			2008	only accept 2008-NaN binaries, if supported
1694				by the FPU
1695			relaxed	accept any binaries regardless of whether
1696				supported by the FPU
1697
1698			The FPU emulator is always able to support both NaN
1699			encodings, so if no FPU hardware is present or it has
1700			been disabled with 'nofpu', then the settings of
1701			'legacy' and '2008' strap the emulator accordingly,
1702			'relaxed' straps the emulator for both legacy-NaN and
1703			2008-NaN, whereas 'strict' enables legacy-NaN only on
1704			legacy processors and both NaN encodings on MIPS32 or
1705			MIPS64 CPUs.
1706
1707			The setting for ABS.fmt/NEG.fmt instruction execution
1708			mode generally follows that for the NaN encoding,
1709			except where unsupported by hardware.
1710
1711	ignore_loglevel	[KNL]
1712			Ignore loglevel setting - this will print /all/
1713			kernel messages to the console. Useful for debugging.
1714			We also add it as printk module parameter, so users
1715			could change it dynamically, usually by
1716			/sys/module/printk/parameters/ignore_loglevel.
1717
1718	ignore_rlimit_data
1719			Ignore RLIMIT_DATA setting for data mappings,
1720			print warning at first misuse.  Can be changed via
1721			/sys/module/kernel/parameters/ignore_rlimit_data.
1722
1723	ihash_entries=	[KNL]
1724			Set number of hash buckets for inode cache.
1725
1726	ima_appraise=	[IMA] appraise integrity measurements
1727			Format: { "off" | "enforce" | "fix" | "log" }
1728			default: "enforce"
1729
1730	ima_appraise_tcb [IMA] Deprecated.  Use ima_policy= instead.
1731			The builtin appraise policy appraises all files
1732			owned by uid=0.
1733
1734	ima_canonical_fmt [IMA]
1735			Use the canonical format for the binary runtime
1736			measurements, instead of host native format.
1737
1738	ima_hash=	[IMA]
1739			Format: { md5 | sha1 | rmd160 | sha256 | sha384
1740				   | sha512 | ... }
1741			default: "sha1"
1742
1743			The list of supported hash algorithms is defined
1744			in crypto/hash_info.h.
1745
1746	ima_policy=	[IMA]
1747			The builtin policies to load during IMA setup.
1748			Format: "tcb | appraise_tcb | secure_boot |
1749				 fail_securely"
1750
1751			The "tcb" policy measures all programs exec'd, files
1752			mmap'd for exec, and all files opened with the read
1753			mode bit set by either the effective uid (euid=0) or
1754			uid=0.
1755
1756			The "appraise_tcb" policy appraises the integrity of
1757			all files owned by root.
1758
1759			The "secure_boot" policy appraises the integrity
1760			of files (eg. kexec kernel image, kernel modules,
1761			firmware, policy, etc) based on file signatures.
1762
1763			The "fail_securely" policy forces file signature
1764			verification failure also on privileged mounted
1765			filesystems with the SB_I_UNVERIFIABLE_SIGNATURE
1766			flag.
1767
1768	ima_tcb		[IMA] Deprecated.  Use ima_policy= instead.
1769			Load a policy which meets the needs of the Trusted
1770			Computing Base.  This means IMA will measure all
1771			programs exec'd, files mmap'd for exec, and all files
1772			opened for read by uid=0.
1773
1774	ima_template=	[IMA]
1775			Select one of defined IMA measurements template formats.
1776			Formats: { "ima" | "ima-ng" | "ima-sig" }
1777			Default: "ima-ng"
1778
1779	ima_template_fmt=
1780			[IMA] Define a custom template format.
1781			Format: { "field1|...|fieldN" }
1782
1783	ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
1784			Format: <min_file_size>
1785			Set the minimal file size for using asynchronous hash.
1786			If left unspecified, ahash usage is disabled.
1787
1788			ahash performance varies for different data sizes on
1789			different crypto accelerators. This option can be used
1790			to achieve the best performance for a particular HW.
1791
1792	ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
1793			Format: <bufsize>
1794			Set hashing buffer size. Default: 4k.
1795
1796			ahash performance varies for different chunk sizes on
1797			different crypto accelerators. This option can be used
1798			to achieve best performance for particular HW.
1799
1800	init=		[KNL]
1801			Format: <full_path>
1802			Run specified binary instead of /sbin/init as init
1803			process.
1804
1805	initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
1806			for working out where the kernel is dying during
1807			startup.
1808
1809	initcall_blacklist=  [KNL] Do not execute a comma-separated list of
1810			initcall functions.  Useful for debugging built-in
1811			modules and initcalls.
1812
1813	initrd=		[BOOT] Specify the location of the initial ramdisk
1814
1815	initrdmem=	[KNL] Specify a physical address and size from which to
1816			load the initrd. If an initrd is compiled in or
1817			specified in the bootparams, it takes priority over this
1818			setting.
1819			Format: ss[KMG],nn[KMG]
1820			Default is 0, 0
1821
1822	init_on_alloc=	[MM] Fill newly allocated pages and heap objects with
1823			zeroes.
1824			Format: 0 | 1
1825			Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON.
1826
1827	init_on_free=	[MM] Fill freed pages and heap objects with zeroes.
1828			Format: 0 | 1
1829			Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON.
1830
1831	init_pkru=	[X86] Specify the default memory protection keys rights
1832			register contents for all processes.  0x55555554 by
1833			default (disallow access to all but pkey 0).  Can
1834			override in debugfs after boot.
1835
1836	inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
1837			Format: <irq>
1838
1839	int_pln_enable	[X86] Enable power limit notification interrupt
1840
1841	integrity_audit=[IMA]
1842			Format: { "0" | "1" }
1843			0 -- basic integrity auditing messages. (Default)
1844			1 -- additional integrity auditing messages.
1845
1846	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
1847		on
1848			Enable intel iommu driver.
1849		off
1850			Disable intel iommu driver.
1851		igfx_off [Default Off]
1852			By default, gfx is mapped as normal device. If a gfx
1853			device has a dedicated DMAR unit, the DMAR unit is
1854			bypassed by not enabling DMAR with this option. In
1855			this case, gfx device will use physical address for
1856			DMA.
1857		forcedac [X86-64]
1858			With this option iommu will not optimize to look
1859			for io virtual address below 32-bit forcing dual
1860			address cycle on pci bus for cards supporting greater
1861			than 32-bit addressing. The default is to look
1862			for translation below 32-bit and if not available
1863			then look in the higher range.
1864		strict [Default Off]
1865			With this option on every unmap_single operation will
1866			result in a hardware IOTLB flush operation as opposed
1867			to batching them for performance.
1868		sp_off [Default Off]
1869			By default, super page will be supported if Intel IOMMU
1870			has the capability. With this option, super page will
1871			not be supported.
1872		sm_on [Default Off]
1873			By default, scalable mode will be disabled even if the
1874			hardware advertises that it has support for the scalable
1875			mode translation. With this option set, scalable mode
1876			will be used on hardware which claims to support it.
1877		tboot_noforce [Default Off]
1878			Do not force the Intel IOMMU enabled under tboot.
1879			By default, tboot will force Intel IOMMU on, which
1880			could harm performance of some high-throughput
1881			devices like 40GBit network cards, even if identity
1882			mapping is enabled.
1883			Note that using this option lowers the security
1884			provided by tboot because it makes the system
1885			vulnerable to DMA attacks.
1886		nobounce [Default off]
1887			Disable bounce buffer for untrusted devices such as
1888			the Thunderbolt devices. This will treat the untrusted
1889			devices as the trusted ones, hence might expose security
1890			risks of DMA attacks.
1891
1892	intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
1893			0	disables intel_idle and fall back on acpi_idle.
1894			1 to 9	specify maximum depth of C-state.
1895
1896	intel_pstate=	[X86]
1897			disable
1898			  Do not enable intel_pstate as the default
1899			  scaling driver for the supported processors
1900			passive
1901			  Use intel_pstate as a scaling driver, but configure it
1902			  to work with generic cpufreq governors (instead of
1903			  enabling its internal governor).  This mode cannot be
1904			  used along with the hardware-managed P-states (HWP)
1905			  feature.
1906			force
1907			  Enable intel_pstate on systems that prohibit it by default
1908			  in favor of acpi-cpufreq. Forcing the intel_pstate driver
1909			  instead of acpi-cpufreq may disable platform features, such
1910			  as thermal controls and power capping, that rely on ACPI
1911			  P-States information being indicated to OSPM and therefore
1912			  should be used with caution. This option does not work with
1913			  processors that aren't supported by the intel_pstate driver
1914			  or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
1915			no_hwp
1916			  Do not enable hardware P state control (HWP)
1917			  if available.
1918			hwp_only
1919			  Only load intel_pstate on systems which support
1920			  hardware P state control (HWP) if available.
1921			support_acpi_ppc
1922			  Enforce ACPI _PPC performance limits. If the Fixed ACPI
1923			  Description Table, specifies preferred power management
1924			  profile as "Enterprise Server" or "Performance Server",
1925			  then this feature is turned on by default.
1926			per_cpu_perf_limits
1927			  Allow per-logical-CPU P-State performance control limits using
1928			  cpufreq sysfs interface
1929
1930	intremap=	[X86-64, Intel-IOMMU]
1931			on	enable Interrupt Remapping (default)
1932			off	disable Interrupt Remapping
1933			nosid	disable Source ID checking
1934			no_x2apic_optout
1935				BIOS x2APIC opt-out request will be ignored
1936			nopost	disable Interrupt Posting
1937
1938	iomem=		Disable strict checking of access to MMIO memory
1939		strict	regions from userspace.
1940		relaxed
1941
1942	iommu=		[X86]
1943		off
1944		force
1945		noforce
1946		biomerge
1947		panic
1948		nopanic
1949		merge
1950		nomerge
1951		soft
1952		pt		[X86]
1953		nopt		[X86]
1954		nobypass	[PPC/POWERNV]
1955			Disable IOMMU bypass, using IOMMU for PCI devices.
1956
1957	iommu.strict=	[ARM64] Configure TLB invalidation behaviour
1958			Format: { "0" | "1" }
1959			0 - Lazy mode.
1960			  Request that DMA unmap operations use deferred
1961			  invalidation of hardware TLBs, for increased
1962			  throughput at the cost of reduced device isolation.
1963			  Will fall back to strict mode if not supported by
1964			  the relevant IOMMU driver.
1965			1 - Strict mode (default).
1966			  DMA unmap operations invalidate IOMMU hardware TLBs
1967			  synchronously.
1968
1969	iommu.passthrough=
1970			[ARM64, X86] Configure DMA to bypass the IOMMU by default.
1971			Format: { "0" | "1" }
1972			0 - Use IOMMU translation for DMA.
1973			1 - Bypass the IOMMU for DMA.
1974			unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
1975
1976	io7=		[HW] IO7 for Marvel-based Alpha systems
1977			See comment before marvel_specify_io7 in
1978			arch/alpha/kernel/core_marvel.c.
1979
1980	io_delay=	[X86] I/O delay method
1981		0x80
1982			Standard port 0x80 based delay
1983		0xed
1984			Alternate port 0xed based delay (needed on some systems)
1985		udelay
1986			Simple two microseconds delay
1987		none
1988			No delay
1989
1990	ip=		[IP_PNP]
1991			See Documentation/admin-guide/nfs/nfsroot.rst.
1992
1993	ipcmni_extend	[KNL] Extend the maximum number of unique System V
1994			IPC identifiers from 32,768 to 16,777,216.
1995
1996	irqaffinity=	[SMP] Set the default irq affinity mask
1997			The argument is a cpu list, as described above.
1998
1999	irqchip.gicv2_force_probe=
2000			[ARM, ARM64]
2001			Format: <bool>
2002			Force the kernel to look for the second 4kB page
2003			of a GICv2 controller even if the memory range
2004			exposed by the device tree is too small.
2005
2006	irqchip.gicv3_nolpi=
2007			[ARM, ARM64]
2008			Force the kernel to ignore the availability of
2009			LPIs (and by consequence ITSs). Intended for system
2010			that use the kernel as a bootloader, and thus want
2011			to let secondary kernels in charge of setting up
2012			LPIs.
2013
2014	irqchip.gicv3_pseudo_nmi= [ARM64]
2015			Enables support for pseudo-NMIs in the kernel. This
2016			requires the kernel to be built with
2017			CONFIG_ARM64_PSEUDO_NMI.
2018
2019	irqfixup	[HW]
2020			When an interrupt is not handled search all handlers
2021			for it. Intended to get systems with badly broken
2022			firmware running.
2023
2024	irqpoll		[HW]
2025			When an interrupt is not handled search all handlers
2026			for it. Also check all handlers each timer
2027			interrupt. Intended to get systems with badly broken
2028			firmware running.
2029
2030	isapnp=		[ISAPNP]
2031			Format: <RDP>,<reset>,<pci_scan>,<verbosity>
2032
2033	isolcpus=	[KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
2034			[Deprecated - use cpusets instead]
2035			Format: [flag-list,]<cpu-list>
2036
2037			Specify one or more CPUs to isolate from disturbances
2038			specified in the flag list (default: domain):
2039
2040			nohz
2041			  Disable the tick when a single task runs.
2042
2043			  A residual 1Hz tick is offloaded to workqueues, which you
2044			  need to affine to housekeeping through the global
2045			  workqueue's affinity configured via the
2046			  /sys/devices/virtual/workqueue/cpumask sysfs file, or
2047			  by using the 'domain' flag described below.
2048
2049			  NOTE: by default the global workqueue runs on all CPUs,
2050			  so to protect individual CPUs the 'cpumask' file has to
2051			  be configured manually after bootup.
2052
2053			domain
2054			  Isolate from the general SMP balancing and scheduling
2055			  algorithms. Note that performing domain isolation this way
2056			  is irreversible: it's not possible to bring back a CPU to
2057			  the domains once isolated through isolcpus. It's strongly
2058			  advised to use cpusets instead to disable scheduler load
2059			  balancing through the "cpuset.sched_load_balance" file.
2060			  It offers a much more flexible interface where CPUs can
2061			  move in and out of an isolated set anytime.
2062
2063			  You can move a process onto or off an "isolated" CPU via
2064			  the CPU affinity syscalls or cpuset.
2065			  <cpu number> begins at 0 and the maximum value is
2066			  "number of CPUs in system - 1".
2067
2068			managed_irq
2069
2070			  Isolate from being targeted by managed interrupts
2071			  which have an interrupt mask containing isolated
2072			  CPUs. The affinity of managed interrupts is
2073			  handled by the kernel and cannot be changed via
2074			  the /proc/irq/* interfaces.
2075
2076			  This isolation is best effort and only effective
2077			  if the automatically assigned interrupt mask of a
2078			  device queue contains isolated and housekeeping
2079			  CPUs. If housekeeping CPUs are online then such
2080			  interrupts are directed to the housekeeping CPU
2081			  so that IO submitted on the housekeeping CPU
2082			  cannot disturb the isolated CPU.
2083
2084			  If a queue's affinity mask contains only isolated
2085			  CPUs then this parameter has no effect on the
2086			  interrupt routing decision, though interrupts are
2087			  only delivered when tasks running on those
2088			  isolated CPUs submit IO. IO submitted on
2089			  housekeeping CPUs has no influence on those
2090			  queues.
2091
2092			The format of <cpu-list> is described above.
2093
2094	iucv=		[HW,NET]
2095
2096	ivrs_ioapic	[HW,X86-64]
2097			Provide an override to the IOAPIC-ID<->DEVICE-ID
2098			mapping provided in the IVRS ACPI table. For
2099			example, to map IOAPIC-ID decimal 10 to
2100			PCI device 00:14.0 write the parameter as:
2101				ivrs_ioapic[10]=00:14.0
2102
2103	ivrs_hpet	[HW,X86-64]
2104			Provide an override to the HPET-ID<->DEVICE-ID
2105			mapping provided in the IVRS ACPI table. For
2106			example, to map HPET-ID decimal 0 to
2107			PCI device 00:14.0 write the parameter as:
2108				ivrs_hpet[0]=00:14.0
2109
2110	ivrs_acpihid	[HW,X86-64]
2111			Provide an override to the ACPI-HID:UID<->DEVICE-ID
2112			mapping provided in the IVRS ACPI table. For
2113			example, to map UART-HID:UID AMD0020:0 to
2114			PCI device 00:14.5 write the parameter as:
2115				ivrs_acpihid[00:14.5]=AMD0020:0
2116
2117	js=		[HW,JOY] Analog joystick
2118			See Documentation/input/joydev/joystick.rst.
2119
2120	nokaslr		[KNL]
2121			When CONFIG_RANDOMIZE_BASE is set, this disables
2122			kernel and module base offset ASLR (Address Space
2123			Layout Randomization).
2124
2125	kasan_multi_shot
2126			[KNL] Enforce KASAN (Kernel Address Sanitizer) to print
2127			report on every invalid memory access. Without this
2128			parameter KASAN will print report only for the first
2129			invalid access.
2130
2131	keepinitrd	[HW,ARM]
2132
2133	kernelcore=	[KNL,X86,IA-64,PPC]
2134			Format: nn[KMGTPE] | nn% | "mirror"
2135			This parameter specifies the amount of memory usable by
2136			the kernel for non-movable allocations.  The requested
2137			amount is spread evenly throughout all nodes in the
2138			system as ZONE_NORMAL.  The remaining memory is used for
2139			movable memory in its own zone, ZONE_MOVABLE.  In the
2140			event, a node is too small to have both ZONE_NORMAL and
2141			ZONE_MOVABLE, kernelcore memory will take priority and
2142			other nodes will have a larger ZONE_MOVABLE.
2143
2144			ZONE_MOVABLE is used for the allocation of pages that
2145			may be reclaimed or moved by the page migration
2146			subsystem.  Note that allocations like PTEs-from-HighMem
2147			still use the HighMem zone if it exists, and the Normal
2148			zone if it does not.
2149
2150			It is possible to specify the exact amount of memory in
2151			the form of "nn[KMGTPE]", a percentage of total system
2152			memory in the form of "nn%", or "mirror".  If "mirror"
2153			option is specified, mirrored (reliable) memory is used
2154			for non-movable allocations and remaining memory is used
2155			for Movable pages.  "nn[KMGTPE]", "nn%", and "mirror"
2156			are exclusive, so you cannot specify multiple forms.
2157
2158	kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
2159			Format: <Controller#>[,poll interval]
2160			The controller # is the number of the ehci usb debug
2161			port as it is probed via PCI.  The poll interval is
2162			optional and is the number seconds in between
2163			each poll cycle to the debug port in case you need
2164			the functionality for interrupting the kernel with
2165			gdb or control-c on the dbgp connection.  When
2166			not using this parameter you use sysrq-g to break into
2167			the kernel debugger.
2168
2169	kgdboc=		[KGDB,HW] kgdb over consoles.
2170			Requires a tty driver that supports console polling,
2171			or a supported polling keyboard driver (non-usb).
2172			 Serial only format: <serial_device>[,baud]
2173			 keyboard only format: kbd
2174			 keyboard and serial format: kbd,<serial_device>[,baud]
2175			Optional Kernel mode setting:
2176			 kms, kbd format: kms,kbd
2177			 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
2178
2179	kgdboc_earlycon=	[KGDB,HW]
2180			If the boot console provides the ability to read
2181			characters and can work in polling mode, you can use
2182			this parameter to tell kgdb to use it as a backend
2183			until the normal console is registered. Intended to
2184			be used together with the kgdboc parameter which
2185			specifies the normal console to transition to.
2186
2187			The name of the early console should be specified
2188			as the value of this parameter. Note that the name of
2189			the early console might be different than the tty
2190			name passed to kgdboc. It's OK to leave the value
2191			blank and the first boot console that implements
2192			read() will be picked.
2193
2194	kgdbwait	[KGDB] Stop kernel execution and enter the
2195			kernel debugger at the earliest opportunity.
2196
2197	kmac=		[MIPS] Korina ethernet MAC address.
2198			Configure the RouterBoard 532 series on-chip
2199			Ethernet adapter MAC address.
2200
2201	kmemleak=	[KNL] Boot-time kmemleak enable/disable
2202			Valid arguments: on, off
2203			Default: on
2204			Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
2205			the default is off.
2206
2207	kprobe_event=[probe-list]
2208			[FTRACE] Add kprobe events and enable at boot time.
2209			The probe-list is a semicolon delimited list of probe
2210			definitions. Each definition is same as kprobe_events
2211			interface, but the parameters are comma delimited.
2212			For example, to add a kprobe event on vfs_read with
2213			arg1 and arg2, add to the command line;
2214
2215			      kprobe_event=p,vfs_read,$arg1,$arg2
2216
2217			See also Documentation/trace/kprobetrace.rst "Kernel
2218			Boot Parameter" section.
2219
2220	kpti=		[ARM64] Control page table isolation of user
2221			and kernel address spaces.
2222			Default: enabled on cores which need mitigation.
2223			0: force disabled
2224			1: force enabled
2225
2226	kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
2227			Default is 0 (don't ignore, but inject #GP)
2228
2229	kvm.enable_vmware_backdoor=[KVM] Support VMware backdoor PV interface.
2230				   Default is false (don't support).
2231
2232	kvm.mmu_audit=	[KVM] This is a R/W parameter which allows audit
2233			KVM MMU at runtime.
2234			Default is 0 (off)
2235
2236	kvm.nx_huge_pages=
2237			[KVM] Controls the software workaround for the
2238			X86_BUG_ITLB_MULTIHIT bug.
2239			force	: Always deploy workaround.
2240			off	: Never deploy workaround.
2241			auto    : Deploy workaround based on the presence of
2242				  X86_BUG_ITLB_MULTIHIT.
2243
2244			Default is 'auto'.
2245
2246			If the software workaround is enabled for the host,
2247			guests do need not to enable it for nested guests.
2248
2249	kvm.nx_huge_pages_recovery_ratio=
2250			[KVM] Controls how many 4KiB pages are periodically zapped
2251			back to huge pages.  0 disables the recovery, otherwise if
2252			the value is N KVM will zap 1/Nth of the 4KiB pages every
2253			minute.  The default is 60.
2254
2255	kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.
2256			Default is 1 (enabled)
2257
2258	kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)
2259			for all guests.
2260			Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
2261
2262	kvm-arm.vgic_v3_group0_trap=
2263			[KVM,ARM] Trap guest accesses to GICv3 group-0
2264			system registers
2265
2266	kvm-arm.vgic_v3_group1_trap=
2267			[KVM,ARM] Trap guest accesses to GICv3 group-1
2268			system registers
2269
2270	kvm-arm.vgic_v3_common_trap=
2271			[KVM,ARM] Trap guest accesses to GICv3 common
2272			system registers
2273
2274	kvm-arm.vgic_v4_enable=
2275			[KVM,ARM] Allow use of GICv4 for direct injection of
2276			LPIs.
2277
2278	kvm_cma_resv_ratio=n [PPC]
2279			Reserves given percentage from system memory area for
2280			contiguous memory allocation for KVM hash pagetable
2281			allocation.
2282			By default it reserves 5% of total system memory.
2283			Format: <integer>
2284			Default: 5
2285
2286	kvm-intel.ept=	[KVM,Intel] Disable extended page tables
2287			(virtualized MMU) support on capable Intel chips.
2288			Default is 1 (enabled)
2289
2290	kvm-intel.emulate_invalid_guest_state=
2291			[KVM,Intel] Enable emulation of invalid guest states
2292			Default is 0 (disabled)
2293
2294	kvm-intel.flexpriority=
2295			[KVM,Intel] Disable FlexPriority feature (TPR shadow).
2296			Default is 1 (enabled)
2297
2298	kvm-intel.nested=
2299			[KVM,Intel] Enable VMX nesting (nVMX).
2300			Default is 0 (disabled)
2301
2302	kvm-intel.unrestricted_guest=
2303			[KVM,Intel] Disable unrestricted guest feature
2304			(virtualized real and unpaged mode) on capable
2305			Intel chips. Default is 1 (enabled)
2306
2307	kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2308			CVE-2018-3620.
2309
2310			Valid arguments: never, cond, always
2311
2312			always: L1D cache flush on every VMENTER.
2313			cond:	Flush L1D on VMENTER only when the code between
2314				VMEXIT and VMENTER can leak host memory.
2315			never:	Disables the mitigation
2316
2317			Default is cond (do L1 cache flush in specific instances)
2318
2319	kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification
2320			feature (tagged TLBs) on capable Intel chips.
2321			Default is 1 (enabled)
2322
2323	l1tf=           [X86] Control mitigation of the L1TF vulnerability on
2324			      affected CPUs
2325
2326			The kernel PTE inversion protection is unconditionally
2327			enabled and cannot be disabled.
2328
2329			full
2330				Provides all available mitigations for the
2331				L1TF vulnerability. Disables SMT and
2332				enables all mitigations in the
2333				hypervisors, i.e. unconditional L1D flush.
2334
2335				SMT control and L1D flush control via the
2336				sysfs interface is still possible after
2337				boot.  Hypervisors will issue a warning
2338				when the first VM is started in a
2339				potentially insecure configuration,
2340				i.e. SMT enabled or L1D flush disabled.
2341
2342			full,force
2343				Same as 'full', but disables SMT and L1D
2344				flush runtime control. Implies the
2345				'nosmt=force' command line option.
2346				(i.e. sysfs control of SMT is disabled.)
2347
2348			flush
2349				Leaves SMT enabled and enables the default
2350				hypervisor mitigation, i.e. conditional
2351				L1D flush.
2352
2353				SMT control and L1D flush control via the
2354				sysfs interface is still possible after
2355				boot.  Hypervisors will issue a warning
2356				when the first VM is started in a
2357				potentially insecure configuration,
2358				i.e. SMT enabled or L1D flush disabled.
2359
2360			flush,nosmt
2361
2362				Disables SMT and enables the default
2363				hypervisor mitigation.
2364
2365				SMT control and L1D flush control via the
2366				sysfs interface is still possible after
2367				boot.  Hypervisors will issue a warning
2368				when the first VM is started in a
2369				potentially insecure configuration,
2370				i.e. SMT enabled or L1D flush disabled.
2371
2372			flush,nowarn
2373				Same as 'flush', but hypervisors will not
2374				warn when a VM is started in a potentially
2375				insecure configuration.
2376
2377			off
2378				Disables hypervisor mitigations and doesn't
2379				emit any warnings.
2380				It also drops the swap size and available
2381				RAM limit restriction on both hypervisor and
2382				bare metal.
2383
2384			Default is 'flush'.
2385
2386			For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2387
2388	l2cr=		[PPC]
2389
2390	l3cr=		[PPC]
2391
2392	lapic		[X86-32,APIC] Enable the local APIC even if BIOS
2393			disabled it.
2394
2395	lapic=		[X86,APIC] Do not use TSC deadline
2396			value for LAPIC timer one-shot implementation. Default
2397			back to the programmable timer unit in the LAPIC.
2398			Format: notscdeadline
2399
2400	lapic_timer_c2_ok	[X86,APIC] trust the local apic timer
2401			in C2 power state.
2402
2403	libata.dma=	[LIBATA] DMA control
2404			libata.dma=0	  Disable all PATA and SATA DMA
2405			libata.dma=1	  PATA and SATA Disk DMA only
2406			libata.dma=2	  ATAPI (CDROM) DMA only
2407			libata.dma=4	  Compact Flash DMA only
2408			Combinations also work, so libata.dma=3 enables DMA
2409			for disks and CDROMs, but not CFs.
2410
2411	libata.ignore_hpa=	[LIBATA] Ignore HPA limit
2412			libata.ignore_hpa=0	  keep BIOS limits (default)
2413			libata.ignore_hpa=1	  ignore limits, using full disk
2414
2415	libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
2416			when set.
2417			Format: <int>
2418
2419	libata.force=	[LIBATA] Force configurations.  The format is comma
2420			separated list of "[ID:]VAL" where ID is
2421			PORT[.DEVICE].  PORT and DEVICE are decimal numbers
2422			matching port, link or device.  Basically, it matches
2423			the ATA ID string printed on console by libata.  If
2424			the whole ID part is omitted, the last PORT and DEVICE
2425			values are used.  If ID hasn't been specified yet, the
2426			configuration applies to all ports, links and devices.
2427
2428			If only DEVICE is omitted, the parameter applies to
2429			the port and all links and devices behind it.  DEVICE
2430			number of 0 either selects the first device or the
2431			first fan-out link behind PMP device.  It does not
2432			select the host link.  DEVICE number of 15 selects the
2433			host link and device attached to it.
2434
2435			The VAL specifies the configuration to force.  As long
2436			as there's no ambiguity shortcut notation is allowed.
2437			For example, both 1.5 and 1.5G would work for 1.5Gbps.
2438			The following configurations can be forced.
2439
2440			* Cable type: 40c, 80c, short40c, unk, ign or sata.
2441			  Any ID with matching PORT is used.
2442
2443			* SATA link speed limit: 1.5Gbps or 3.0Gbps.
2444
2445			* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2446			  udma[/][16,25,33,44,66,100,133] notation is also
2447			  allowed.
2448
2449			* [no]ncq: Turn on or off NCQ.
2450
2451			* [no]ncqtrim: Turn off queued DSM TRIM.
2452
2453			* nohrst, nosrst, norst: suppress hard, soft
2454			  and both resets.
2455
2456			* rstonce: only attempt one reset during
2457			  hot-unplug link recovery
2458
2459			* dump_id: dump IDENTIFY data.
2460
2461			* atapi_dmadir: Enable ATAPI DMADIR bridge support
2462
2463			* disable: Disable this device.
2464
2465			If there are multiple matching configurations changing
2466			the same attribute, the last one is used.
2467
2468	memblock=debug	[KNL] Enable memblock debug messages.
2469
2470	load_ramdisk=	[RAM] [Deprecated]
2471
2472	lockd.nlm_grace_period=P  [NFS] Assign grace period.
2473			Format: <integer>
2474
2475	lockd.nlm_tcpport=N	[NFS] Assign TCP port.
2476			Format: <integer>
2477
2478	lockd.nlm_timeout=T	[NFS] Assign timeout value.
2479			Format: <integer>
2480
2481	lockd.nlm_udpport=M	[NFS] Assign UDP port.
2482			Format: <integer>
2483
2484	lockdown=	[SECURITY]
2485			{ integrity | confidentiality }
2486			Enable the kernel lockdown feature. If set to
2487			integrity, kernel features that allow userland to
2488			modify the running kernel are disabled. If set to
2489			confidentiality, kernel features that allow userland
2490			to extract confidential information from the kernel
2491			are also disabled.
2492
2493	locktorture.nreaders_stress= [KNL]
2494			Set the number of locking read-acquisition kthreads.
2495			Defaults to being automatically set based on the
2496			number of online CPUs.
2497
2498	locktorture.nwriters_stress= [KNL]
2499			Set the number of locking write-acquisition kthreads.
2500
2501	locktorture.onoff_holdoff= [KNL]
2502			Set time (s) after boot for CPU-hotplug testing.
2503
2504	locktorture.onoff_interval= [KNL]
2505			Set time (s) between CPU-hotplug operations, or
2506			zero to disable CPU-hotplug testing.
2507
2508	locktorture.shuffle_interval= [KNL]
2509			Set task-shuffle interval (jiffies).  Shuffling
2510			tasks allows some CPUs to go into dyntick-idle
2511			mode during the locktorture test.
2512
2513	locktorture.shutdown_secs= [KNL]
2514			Set time (s) after boot system shutdown.  This
2515			is useful for hands-off automated testing.
2516
2517	locktorture.stat_interval= [KNL]
2518			Time (s) between statistics printk()s.
2519
2520	locktorture.stutter= [KNL]
2521			Time (s) to stutter testing, for example,
2522			specifying five seconds causes the test to run for
2523			five seconds, wait for five seconds, and so on.
2524			This tests the locking primitive's ability to
2525			transition abruptly to and from idle.
2526
2527	locktorture.torture_type= [KNL]
2528			Specify the locking implementation to test.
2529
2530	locktorture.verbose= [KNL]
2531			Enable additional printk() statements.
2532
2533	logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
2534			Format: <irq>
2535
2536	loglevel=	All Kernel Messages with a loglevel smaller than the
2537			console loglevel will be printed to the console. It can
2538			also be changed with klogd or other programs. The
2539			loglevels are defined as follows:
2540
2541			0 (KERN_EMERG)		system is unusable
2542			1 (KERN_ALERT)		action must be taken immediately
2543			2 (KERN_CRIT)		critical conditions
2544			3 (KERN_ERR)		error conditions
2545			4 (KERN_WARNING)	warning conditions
2546			5 (KERN_NOTICE)		normal but significant condition
2547			6 (KERN_INFO)		informational
2548			7 (KERN_DEBUG)		debug-level messages
2549
2550	log_buf_len=n[KMG]	Sets the size of the printk ring buffer,
2551			in bytes.  n must be a power of two and greater
2552			than the minimal size. The minimal size is defined
2553			by LOG_BUF_SHIFT kernel config parameter. There is
2554			also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
2555			that allows to increase the default size depending on
2556			the number of CPUs. See init/Kconfig for more details.
2557
2558	logo.nologo	[FB] Disables display of the built-in Linux logo.
2559			This may be used to provide more screen space for
2560			kernel log messages and is useful when debugging
2561			kernel boot problems.
2562
2563	lp=0		[LP]	Specify parallel ports to use, e.g,
2564	lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
2565	lp=reset		first parallel port). 'lp=0' disables the
2566	lp=auto			printer driver. 'lp=reset' (which can be
2567				specified in addition to the ports) causes
2568				attached printers to be reset. Using
2569				lp=port1,port2,... specifies the parallel ports
2570				to associate lp devices with, starting with
2571				lp0. A port specification may be 'none' to skip
2572				that lp device, or a parport name such as
2573				'parport0'. Specifying 'lp=auto' instead of a
2574				port specification list means that device IDs
2575				from each port should be examined, to see if
2576				an IEEE 1284-compliant printer is attached; if
2577				so, the driver will manage that printer.
2578				See also header of drivers/char/lp.c.
2579
2580	lpj=n		[KNL]
2581			Sets loops_per_jiffy to given constant, thus avoiding
2582			time-consuming boot-time autodetection (up to 250 ms per
2583			CPU). 0 enables autodetection (default). To determine
2584			the correct value for your kernel, boot with normal
2585			autodetection and see what value is printed. Note that
2586			on SMP systems the preset will be applied to all CPUs,
2587			which is likely to cause problems if your CPUs need
2588			significantly divergent settings. An incorrect value
2589			will cause delays in the kernel to be wrong, leading to
2590			unpredictable I/O errors and other breakage. Although
2591			unlikely, in the extreme case this might damage your
2592			hardware.
2593
2594	ltpc=		[NET]
2595			Format: <io>,<irq>,<dma>
2596
2597	lsm.debug	[SECURITY] Enable LSM initialization debugging output.
2598
2599	lsm=lsm1,...,lsmN
2600			[SECURITY] Choose order of LSM initialization. This
2601			overrides CONFIG_LSM, and the "security=" parameter.
2602
2603	machvec=	[IA-64] Force the use of a particular machine-vector
2604			(machvec) in a generic kernel.
2605			Example: machvec=hpzx1
2606
2607	machtype=	[Loongson] Share the same kernel image file between
2608			different yeeloong laptops.
2609			Example: machtype=lemote-yeeloong-2f-7inch
2610
2611	max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater
2612			than or equal to this physical address is ignored.
2613
2614	maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
2615			will bring up during bootup.  maxcpus=n : n >= 0 limits
2616			the kernel to bring up 'n' processors. Surely after
2617			bootup you can bring up the other plugged cpu by executing
2618			"echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus
2619			only takes effect during system bootup.
2620			While n=0 is a special case, it is equivalent to "nosmp",
2621			which also disables the IO APIC.
2622
2623	max_loop=	[LOOP] The number of loop block devices that get
2624	(loop.max_loop)	unconditionally pre-created at init time. The default
2625			number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
2626			of statically allocating a predefined number, loop
2627			devices can be requested on-demand with the
2628			/dev/loop-control interface.
2629
2630	mce		[X86-32] Machine Check Exception
2631
2632	mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.rst
2633
2634	md=		[HW] RAID subsystems devices and level
2635			See Documentation/admin-guide/md.rst.
2636
2637	mdacon=		[MDA]
2638			Format: <first>,<last>
2639			Specifies range of consoles to be captured by the MDA.
2640
2641	mds=		[X86,INTEL]
2642			Control mitigation for the Micro-architectural Data
2643			Sampling (MDS) vulnerability.
2644
2645			Certain CPUs are vulnerable to an exploit against CPU
2646			internal buffers which can forward information to a
2647			disclosure gadget under certain conditions.
2648
2649			In vulnerable processors, the speculatively
2650			forwarded data can be used in a cache side channel
2651			attack, to access data to which the attacker does
2652			not have direct access.
2653
2654			This parameter controls the MDS mitigation. The
2655			options are:
2656
2657			full       - Enable MDS mitigation on vulnerable CPUs
2658			full,nosmt - Enable MDS mitigation and disable
2659				     SMT on vulnerable CPUs
2660			off        - Unconditionally disable MDS mitigation
2661
2662			On TAA-affected machines, mds=off can be prevented by
2663			an active TAA mitigation as both vulnerabilities are
2664			mitigated with the same mechanism so in order to disable
2665			this mitigation, you need to specify tsx_async_abort=off
2666			too.
2667
2668			Not specifying this option is equivalent to
2669			mds=full.
2670
2671			For details see: Documentation/admin-guide/hw-vuln/mds.rst
2672
2673	mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
2674			Amount of memory to be used in cases as follows:
2675
2676			1 for test;
2677			2 when the kernel is not able to see the whole system memory;
2678			3 memory that lies after 'mem=' boundary is excluded from
2679			 the hypervisor, then assigned to KVM guests.
2680
2681			[X86] Work as limiting max address. Use together
2682			with memmap= to avoid physical address space collisions.
2683			Without memmap= PCI devices could be placed at addresses
2684			belonging to unused RAM.
2685
2686			Note that this only takes effects during boot time since
2687			in above case 3, memory may need be hot added after boot
2688			if system memory of hypervisor is not sufficient.
2689
2690	mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
2691			memory.
2692
2693	memchunk=nn[KMG]
2694			[KNL,SH] Allow user to override the default size for
2695			per-device physically contiguous DMA buffers.
2696
2697	memhp_default_state=online/offline
2698			[KNL] Set the initial state for the memory hotplug
2699			onlining policy. If not specified, the default value is
2700			set according to the
2701			CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
2702			option.
2703			See Documentation/admin-guide/mm/memory-hotplug.rst.
2704
2705	memmap=exactmap	[KNL,X86] Enable setting of an exact
2706			E820 memory map, as specified by the user.
2707			Such memmap=exactmap lines can be constructed based on
2708			BIOS output or other requirements. See the memmap=nn@ss
2709			option description.
2710
2711	memmap=nn[KMG]@ss[KMG]
2712			[KNL] Force usage of a specific region of memory.
2713			Region of memory to be used is from ss to ss+nn.
2714			If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG],
2715			which limits max address to nn[KMG].
2716			Multiple different regions can be specified,
2717			comma delimited.
2718			Example:
2719				memmap=100M@2G,100M#3G,1G!1024G
2720
2721	memmap=nn[KMG]#ss[KMG]
2722			[KNL,ACPI] Mark specific memory as ACPI data.
2723			Region of memory to be marked is from ss to ss+nn.
2724
2725	memmap=nn[KMG]$ss[KMG]
2726			[KNL,ACPI] Mark specific memory as reserved.
2727			Region of memory to be reserved is from ss to ss+nn.
2728			Example: Exclude memory from 0x18690000-0x1869ffff
2729			         memmap=64K$0x18690000
2730			         or
2731			         memmap=0x10000$0x18690000
2732			Some bootloaders may need an escape character before '$',
2733			like Grub2, otherwise '$' and the following number
2734			will be eaten.
2735
2736	memmap=nn[KMG]!ss[KMG]
2737			[KNL,X86] Mark specific memory as protected.
2738			Region of memory to be used, from ss to ss+nn.
2739			The memory region may be marked as e820 type 12 (0xc)
2740			and is NVDIMM or ADR memory.
2741
2742	memmap=<size>%<offset>-<oldtype>+<newtype>
2743			[KNL,ACPI] Convert memory within the specified region
2744			from <oldtype> to <newtype>. If "-<oldtype>" is left
2745			out, the whole region will be marked as <newtype>,
2746			even if previously unavailable. If "+<newtype>" is left
2747			out, matching memory will be removed. Types are
2748			specified as e820 types, e.g., 1 = RAM, 2 = reserved,
2749			3 = ACPI, 12 = PRAM.
2750
2751	memory_corruption_check=0/1 [X86]
2752			Some BIOSes seem to corrupt the first 64k of
2753			memory when doing things like suspend/resume.
2754			Setting this option will scan the memory
2755			looking for corruption.  Enabling this will
2756			both detect corruption and prevent the kernel
2757			from using the memory being corrupted.
2758			However, its intended as a diagnostic tool; if
2759			repeatable BIOS-originated corruption always
2760			affects the same memory, you can use memmap=
2761			to prevent the kernel from using that memory.
2762
2763	memory_corruption_check_size=size [X86]
2764			By default it checks for corruption in the low
2765			64k, making this memory unavailable for normal
2766			use.  Use this parameter to scan for
2767			corruption in more or less memory.
2768
2769	memory_corruption_check_period=seconds [X86]
2770			By default it checks for corruption every 60
2771			seconds.  Use this parameter to check at some
2772			other rate.  0 disables periodic checking.
2773
2774	memtest=	[KNL,X86,ARM,PPC] Enable memtest
2775			Format: <integer>
2776			default : 0 <disable>
2777			Specifies the number of memtest passes to be
2778			performed. Each pass selects another test
2779			pattern from a given set of patterns. Memtest
2780			fills the memory with this pattern, validates
2781			memory contents and reserves bad memory
2782			regions that are detected.
2783
2784	mem_encrypt=	[X86-64] AMD Secure Memory Encryption (SME) control
2785			Valid arguments: on, off
2786			Default (depends on kernel configuration option):
2787			  on  (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y)
2788			  off (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n)
2789			mem_encrypt=on:		Activate SME
2790			mem_encrypt=off:	Do not activate SME
2791
2792			Refer to Documentation/virt/kvm/amd-memory-encryption.rst
2793			for details on when memory encryption can be activated.
2794
2795	mem_sleep_default=	[SUSPEND] Default system suspend mode:
2796			s2idle  - Suspend-To-Idle
2797			shallow - Power-On Suspend or equivalent (if supported)
2798			deep    - Suspend-To-RAM or equivalent (if supported)
2799			See Documentation/admin-guide/pm/sleep-states.rst.
2800
2801	meye.*=		[HW] Set MotionEye Camera parameters
2802			See Documentation/admin-guide/media/meye.rst.
2803
2804	mfgpt_irq=	[IA-32] Specify the IRQ to use for the
2805			Multi-Function General Purpose Timers on AMD Geode
2806			platforms.
2807
2808	mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
2809			the BIOS has incorrectly applied a workaround. TinyBIOS
2810			version 0.98 is known to be affected, 0.99 fixes the
2811			problem by letting the user disable the workaround.
2812
2813	mga=		[HW,DRM]
2814
2815	min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this
2816			physical address is ignored.
2817
2818	mini2440=	[ARM,HW,KNL]
2819			Format:[0..2][b][c][t]
2820			Default: "0tb"
2821			MINI2440 configuration specification:
2822			0 - The attached screen is the 3.5" TFT
2823			1 - The attached screen is the 7" TFT
2824			2 - The VGA Shield is attached (1024x768)
2825			Leaving out the screen size parameter will not load
2826			the TFT driver, and the framebuffer will be left
2827			unconfigured.
2828			b - Enable backlight. The TFT backlight pin will be
2829			linked to the kernel VESA blanking code and a GPIO
2830			LED. This parameter is not necessary when using the
2831			VGA shield.
2832			c - Enable the s3c camera interface.
2833			t - Reserved for enabling touchscreen support. The
2834			touchscreen support is not enabled in the mainstream
2835			kernel as of 2.6.30, a preliminary port can be found
2836			in the "bleeding edge" mini2440 support kernel at
2837			https://repo.or.cz/w/linux-2.6/mini2440.git
2838
2839	mitigations=
2840			[X86,PPC,S390,ARM64] Control optional mitigations for
2841			CPU vulnerabilities.  This is a set of curated,
2842			arch-independent options, each of which is an
2843			aggregation of existing arch-specific options.
2844
2845			off
2846				Disable all optional CPU mitigations.  This
2847				improves system performance, but it may also
2848				expose users to several CPU vulnerabilities.
2849				Equivalent to: nopti [X86,PPC]
2850					       kpti=0 [ARM64]
2851					       nospectre_v1 [X86,PPC]
2852					       nobp=0 [S390]
2853					       nospectre_v2 [X86,PPC,S390,ARM64]
2854					       spectre_v2_user=off [X86]
2855					       spec_store_bypass_disable=off [X86,PPC]
2856					       ssbd=force-off [ARM64]
2857					       l1tf=off [X86]
2858					       mds=off [X86]
2859					       tsx_async_abort=off [X86]
2860					       kvm.nx_huge_pages=off [X86]
2861
2862				Exceptions:
2863					       This does not have any effect on
2864					       kvm.nx_huge_pages when
2865					       kvm.nx_huge_pages=force.
2866
2867			auto (default)
2868				Mitigate all CPU vulnerabilities, but leave SMT
2869				enabled, even if it's vulnerable.  This is for
2870				users who don't want to be surprised by SMT
2871				getting disabled across kernel upgrades, or who
2872				have other ways of avoiding SMT-based attacks.
2873				Equivalent to: (default behavior)
2874
2875			auto,nosmt
2876				Mitigate all CPU vulnerabilities, disabling SMT
2877				if needed.  This is for users who always want to
2878				be fully mitigated, even if it means losing SMT.
2879				Equivalent to: l1tf=flush,nosmt [X86]
2880					       mds=full,nosmt [X86]
2881					       tsx_async_abort=full,nosmt [X86]
2882
2883	mminit_loglevel=
2884			[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
2885			parameter allows control of the logging verbosity for
2886			the additional memory initialisation checks. A value
2887			of 0 disables mminit logging and a level of 4 will
2888			log everything. Information is printed at KERN_DEBUG
2889			so loglevel=8 may also need to be specified.
2890
2891	module.sig_enforce
2892			[KNL] When CONFIG_MODULE_SIG is set, this means that
2893			modules without (valid) signatures will fail to load.
2894			Note that if CONFIG_MODULE_SIG_FORCE is set, that
2895			is always true, so this option does nothing.
2896
2897	module_blacklist=  [KNL] Do not load a comma-separated list of
2898			modules.  Useful for debugging problem modules.
2899
2900	mousedev.tap_time=
2901			[MOUSE] Maximum time between finger touching and
2902			leaving touchpad surface for touch to be considered
2903			a tap and be reported as a left button click (for
2904			touchpads working in absolute mode only).
2905			Format: <msecs>
2906	mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
2907			reporting absolute coordinates, such as tablets
2908	mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
2909			reporting absolute coordinates, such as tablets
2910
2911	movablecore=	[KNL,X86,IA-64,PPC]
2912			Format: nn[KMGTPE] | nn%
2913			This parameter is the complement to kernelcore=, it
2914			specifies the amount of memory used for migratable
2915			allocations.  If both kernelcore and movablecore is
2916			specified, then kernelcore will be at *least* the
2917			specified value but may be more.  If movablecore on its
2918			own is specified, the administrator must be careful
2919			that the amount of memory usable for all allocations
2920			is not too small.
2921
2922	movable_node	[KNL] Boot-time switch to make hotplugable memory
2923			NUMA nodes to be movable. This means that the memory
2924			of such nodes will be usable only for movable
2925			allocations which rules out almost all kernel
2926			allocations. Use with caution!
2927
2928	MTD_Partition=	[MTD]
2929			Format: <name>,<region-number>,<size>,<offset>
2930
2931	MTD_Region=	[MTD] Format:
2932			<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
2933
2934	mtdparts=	[MTD]
2935			See drivers/mtd/parsers/cmdlinepart.c
2936
2937	multitce=off	[PPC]  This parameter disables the use of the pSeries
2938			firmware feature for updating multiple TCE entries
2939			at a time.
2940
2941	onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
2942
2943			Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
2944
2945			boundary - index of last SLC block on Flex-OneNAND.
2946				   The remaining blocks are configured as MLC blocks.
2947			lock	 - Configure if Flex-OneNAND boundary should be locked.
2948				   Once locked, the boundary cannot be changed.
2949				   1 indicates lock status, 0 indicates unlock status.
2950
2951	mtdset=		[ARM]
2952			ARM/S3C2412 JIVE boot control
2953
2954			See arch/arm/mach-s3c2412/mach-jive.c
2955
2956	mtouchusb.raw_coordinates=
2957			[HW] Make the MicroTouch USB driver use raw coordinates
2958			('y', default) or cooked coordinates ('n')
2959
2960	mtrr_chunk_size=nn[KMG] [X86]
2961			used for mtrr cleanup. It is largest continuous chunk
2962			that could hold holes aka. UC entries.
2963
2964	mtrr_gran_size=nn[KMG] [X86]
2965			Used for mtrr cleanup. It is granularity of mtrr block.
2966			Default is 1.
2967			Large value could prevent small alignment from
2968			using up MTRRs.
2969
2970	mtrr_spare_reg_nr=n [X86]
2971			Format: <integer>
2972			Range: 0,7 : spare reg number
2973			Default : 1
2974			Used for mtrr cleanup. It is spare mtrr entries number.
2975			Set to 2 or more if your graphical card needs more.
2976
2977	n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card
2978
2979	netdev=		[NET] Network devices parameters
2980			Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
2981			Note that mem_start is often overloaded to mean
2982			something different and driver-specific.
2983			This usage is only documented in each driver source
2984			file if at all.
2985
2986	nf_conntrack.acct=
2987			[NETFILTER] Enable connection tracking flow accounting
2988			0 to disable accounting
2989			1 to enable accounting
2990			Default value is 0.
2991
2992	nfsaddrs=	[NFS] Deprecated.  Use ip= instead.
2993			See Documentation/admin-guide/nfs/nfsroot.rst.
2994
2995	nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
2996			See Documentation/admin-guide/nfs/nfsroot.rst.
2997
2998	nfsrootdebug	[NFS] enable nfsroot debugging messages.
2999			See Documentation/admin-guide/nfs/nfsroot.rst.
3000
3001	nfs.callback_nr_threads=
3002			[NFSv4] set the total number of threads that the
3003			NFS client will assign to service NFSv4 callback
3004			requests.
3005
3006	nfs.callback_tcpport=
3007			[NFS] set the TCP port on which the NFSv4 callback
3008			channel should listen.
3009
3010	nfs.cache_getent=
3011			[NFS] sets the pathname to the program which is used
3012			to update the NFS client cache entries.
3013
3014	nfs.cache_getent_timeout=
3015			[NFS] sets the timeout after which an attempt to
3016			update a cache entry is deemed to have failed.
3017
3018	nfs.idmap_cache_timeout=
3019			[NFS] set the maximum lifetime for idmapper cache
3020			entries.
3021
3022	nfs.enable_ino64=
3023			[NFS] enable 64-bit inode numbers.
3024			If zero, the NFS client will fake up a 32-bit inode
3025			number for the readdir() and stat() syscalls instead
3026			of returning the full 64-bit number.
3027			The default is to return 64-bit inode numbers.
3028
3029	nfs.max_session_cb_slots=
3030			[NFSv4.1] Sets the maximum number of session
3031			slots the client will assign to the callback
3032			channel. This determines the maximum number of
3033			callbacks the client will process in parallel for
3034			a particular server.
3035
3036	nfs.max_session_slots=
3037			[NFSv4.1] Sets the maximum number of session slots
3038			the client will attempt to negotiate with the server.
3039			This limits the number of simultaneous RPC requests
3040			that the client can send to the NFSv4.1 server.
3041			Note that there is little point in setting this
3042			value higher than the max_tcp_slot_table_limit.
3043
3044	nfs.nfs4_disable_idmapping=
3045			[NFSv4] When set to the default of '1', this option
3046			ensures that both the RPC level authentication
3047			scheme and the NFS level operations agree to use
3048			numeric uids/gids if the mount is using the
3049			'sec=sys' security flavour. In effect it is
3050			disabling idmapping, which can make migration from
3051			legacy NFSv2/v3 systems to NFSv4 easier.
3052			Servers that do not support this mode of operation
3053			will be autodetected by the client, and it will fall
3054			back to using the idmapper.
3055			To turn off this behaviour, set the value to '0'.
3056	nfs.nfs4_unique_id=
3057			[NFS4] Specify an additional fixed unique ident-
3058			ification string that NFSv4 clients can insert into
3059			their nfs_client_id4 string.  This is typically a
3060			UUID that is generated at system install time.
3061
3062	nfs.send_implementation_id =
3063			[NFSv4.1] Send client implementation identification
3064			information in exchange_id requests.
3065			If zero, no implementation identification information
3066			will be sent.
3067			The default is to send the implementation identification
3068			information.
3069
3070	nfs.recover_lost_locks =
3071			[NFSv4] Attempt to recover locks that were lost due
3072			to a lease timeout on the server. Please note that
3073			doing this risks data corruption, since there are
3074			no guarantees that the file will remain unchanged
3075			after the locks are lost.
3076			If you want to enable the kernel legacy behaviour of
3077			attempting to recover these locks, then set this
3078			parameter to '1'.
3079			The default parameter value of '0' causes the kernel
3080			not to attempt recovery of lost locks.
3081
3082	nfs4.layoutstats_timer =
3083			[NFSv4.2] Change the rate at which the kernel sends
3084			layoutstats to the pNFS metadata server.
3085
3086			Setting this to value to 0 causes the kernel to use
3087			whatever value is the default set by the layout
3088			driver. A non-zero value sets the minimum interval
3089			in seconds between layoutstats transmissions.
3090
3091	nfsd.nfs4_disable_idmapping=
3092			[NFSv4] When set to the default of '1', the NFSv4
3093			server will return only numeric uids and gids to
3094			clients using auth_sys, and will accept numeric uids
3095			and gids from such clients.  This is intended to ease
3096			migration from NFSv2/v3.
3097
3098	nmi_backtrace.backtrace_idle [KNL]
3099			Dump stacks even of idle CPUs in response to an
3100			NMI stack-backtrace request.
3101
3102	nmi_debug=	[KNL,SH] Specify one or more actions to take
3103			when a NMI is triggered.
3104			Format: [state][,regs][,debounce][,die]
3105
3106	nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels
3107			Format: [panic,][nopanic,][num]
3108			Valid num: 0 or 1
3109			0 - turn hardlockup detector in nmi_watchdog off
3110			1 - turn hardlockup detector in nmi_watchdog on
3111			When panic is specified, panic when an NMI watchdog
3112			timeout occurs (or 'nopanic' to not panic on an NMI
3113			watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set)
3114			To disable both hard and soft lockup detectors,
3115			please see 'nowatchdog'.
3116			This is useful when you use a panic=... timeout and
3117			need the box quickly up again.
3118
3119			These settings can be accessed at runtime via
3120			the nmi_watchdog and hardlockup_panic sysctls.
3121
3122	netpoll.carrier_timeout=
3123			[NET] Specifies amount of time (in seconds) that
3124			netpoll should wait for a carrier. By default netpoll
3125			waits 4 seconds.
3126
3127	no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
3128			emulation library even if a 387 maths coprocessor
3129			is present.
3130
3131	no5lvl		[X86-64] Disable 5-level paging mode. Forces
3132			kernel to use 4-level paging instead.
3133
3134	nofsgsbase	[X86] Disables FSGSBASE instructions.
3135
3136	no_console_suspend
3137			[HW] Never suspend the console
3138			Disable suspending of consoles during suspend and
3139			hibernate operations.  Once disabled, debugging
3140			messages can reach various consoles while the rest
3141			of the system is being put to sleep (ie, while
3142			debugging driver suspend/resume hooks).  This may
3143			not work reliably with all consoles, but is known
3144			to work with serial and VGA consoles.
3145			To facilitate more flexible debugging, we also add
3146			console_suspend, a printk module parameter to control
3147			it. Users could use console_suspend (usually
3148			/sys/module/printk/parameters/console_suspend) to
3149			turn on/off it dynamically.
3150
3151	novmcoredd	[KNL,KDUMP]
3152			Disable device dump. Device dump allows drivers to
3153			append dump data to vmcore so you can collect driver
3154			specified debug info.  Drivers can append the data
3155			without any limit and this data is stored in memory,
3156			so this may cause significant memory stress.  Disabling
3157			device dump can help save memory but the driver debug
3158			data will be no longer available.  This parameter
3159			is only available when CONFIG_PROC_VMCORE_DEVICE_DUMP
3160			is set.
3161
3162	noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
3163			caches in the slab allocator.  Saves per-node memory,
3164			but will impact performance.
3165
3166	noalign		[KNL,ARM]
3167
3168	noaltinstr	[S390] Disables alternative instructions patching
3169			(CPU alternatives feature).
3170
3171	noapic		[SMP,APIC] Tells the kernel to not make use of any
3172			IOAPICs that may be present in the system.
3173
3174	noautogroup	Disable scheduler automatic task group creation.
3175
3176	nobats		[PPC] Do not use BATs for mapping kernel lowmem
3177			on "Classic" PPC cores.
3178
3179	nocache		[ARM]
3180
3181	noclflush	[BUGS=X86] Don't use the CLFLUSH instruction
3182
3183	nodelayacct	[KNL] Disable per-task delay accounting
3184
3185	nodsp		[SH] Disable hardware DSP at boot time.
3186
3187	noefi		Disable EFI runtime services support.
3188
3189	noexec		[IA-64]
3190
3191	noexec		[X86]
3192			On X86-32 available only on PAE configured kernels.
3193			noexec=on: enable non-executable mappings (default)
3194			noexec=off: disable non-executable mappings
3195
3196	nosmap		[X86,PPC]
3197			Disable SMAP (Supervisor Mode Access Prevention)
3198			even if it is supported by processor.
3199
3200	nosmep		[X86,PPC]
3201			Disable SMEP (Supervisor Mode Execution Prevention)
3202			even if it is supported by processor.
3203
3204	noexec32	[X86-64]
3205			This affects only 32-bit executables.
3206			noexec32=on: enable non-executable mappings (default)
3207				read doesn't imply executable mappings
3208			noexec32=off: disable non-executable mappings
3209				read implies executable mappings
3210
3211	nofpu		[MIPS,SH] Disable hardware FPU at boot time.
3212
3213	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
3214			register save and restore. The kernel will only save
3215			legacy floating-point registers on task switch.
3216
3217	nohugeiomap	[KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.
3218
3219	nosmt		[KNL,S390] Disable symmetric multithreading (SMT).
3220			Equivalent to smt=1.
3221
3222			[KNL,X86] Disable symmetric multithreading (SMT).
3223			nosmt=force: Force disable SMT, cannot be undone
3224				     via the sysfs control file.
3225
3226	nospectre_v1	[X86,PPC] Disable mitigations for Spectre Variant 1
3227			(bounds check bypass). With this option data leaks are
3228			possible in the system.
3229
3230	nospectre_v2	[X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for
3231			the Spectre variant 2 (indirect branch prediction)
3232			vulnerability. System may allow data leaks with this
3233			option.
3234
3235	nospec_store_bypass_disable
3236			[HW] Disable all mitigations for the Speculative Store Bypass vulnerability
3237
3238	noxsave		[BUGS=X86] Disables x86 extended register state save
3239			and restore using xsave. The kernel will fallback to
3240			enabling legacy floating-point and sse state.
3241
3242	noxsaveopt	[X86] Disables xsaveopt used in saving x86 extended
3243			register states. The kernel will fall back to use
3244			xsave to save the states. By using this parameter,
3245			performance of saving the states is degraded because
3246			xsave doesn't support modified optimization while
3247			xsaveopt supports it on xsaveopt enabled systems.
3248
3249	noxsaves	[X86] Disables xsaves and xrstors used in saving and
3250			restoring x86 extended register state in compacted
3251			form of xsave area. The kernel will fall back to use
3252			xsaveopt and xrstor to save and restore the states
3253			in standard form of xsave area. By using this
3254			parameter, xsave area per process might occupy more
3255			memory on xsaves enabled systems.
3256
3257	nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
3258			wfi(ARM) instruction doesn't work correctly and not to
3259			use it. This is also useful when using JTAG debugger.
3260
3261	no_file_caps	Tells the kernel not to honor file capabilities.  The
3262			only way then for a file to be executed with privilege
3263			is to be setuid root or executed by root.
3264
3265	nohalt		[IA-64] Tells the kernel not to use the power saving
3266			function PAL_HALT_LIGHT when idle. This increases
3267			power-consumption. On the positive side, it reduces
3268			interrupt wake-up latency, which may improve performance
3269			in certain environments such as networked servers or
3270			real-time systems.
3271
3272	nohibernate	[HIBERNATION] Disable hibernation and resume.
3273
3274	nohz=		[KNL] Boottime enable/disable dynamic ticks
3275			Valid arguments: on, off
3276			Default: on
3277
3278	nohz_full=	[KNL,BOOT,SMP,ISOL]
3279			The argument is a cpu list, as described above.
3280			In kernels built with CONFIG_NO_HZ_FULL=y, set
3281			the specified list of CPUs whose tick will be stopped
3282			whenever possible. The boot CPU will be forced outside
3283			the range to maintain the timekeeping.  Any CPUs
3284			in this list will have their RCU callbacks offloaded,
3285			just as if they had also been called out in the
3286			rcu_nocbs= boot parameter.
3287
3288	noiotrap	[SH] Disables trapped I/O port accesses.
3289
3290	noirqdebug	[X86-32] Disables the code which attempts to detect and
3291			disable unhandled interrupt sources.
3292
3293	no_timer_check	[X86,APIC] Disables the code which tests for
3294			broken timer IRQ sources.
3295
3296	noisapnp	[ISAPNP] Disables ISA PnP code.
3297
3298	noinitrd	[RAM] Tells the kernel not to load any configured
3299			initial RAM disk.
3300
3301	nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt
3302			remapping.
3303			[Deprecated - use intremap=off]
3304
3305	nointroute	[IA-64]
3306
3307	noinvpcid	[X86] Disable the INVPCID cpu feature.
3308
3309	nojitter	[IA-64] Disables jitter checking for ITC timers.
3310
3311	no-kvmclock	[X86,KVM] Disable paravirtualized KVM clock driver
3312
3313	no-kvmapf	[X86,KVM] Disable paravirtualized asynchronous page
3314			fault handling.
3315
3316	no-vmw-sched-clock
3317			[X86,PV_OPS] Disable paravirtualized VMware scheduler
3318			clock and use the default one.
3319
3320	no-steal-acc	[X86,PV_OPS,ARM64] Disable paravirtualized steal time
3321			accounting. steal time is computed, but won't
3322			influence scheduler behaviour
3323
3324	nolapic		[X86-32,APIC] Do not enable or use the local APIC.
3325
3326	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
3327
3328	noltlbs		[PPC] Do not use large page/tlb entries for kernel
3329			lowmem mapping on PPC40x and PPC8xx
3330
3331	nomca		[IA-64] Disable machine check abort handling
3332
3333	nomce		[X86-32] Disable Machine Check Exception
3334
3335	nomfgpt		[X86-32] Disable Multi-Function General Purpose
3336			Timer usage (for AMD Geode machines).
3337
3338	nonmi_ipi	[X86] Disable using NMI IPIs during panic/reboot to
3339			shutdown the other cpus.  Instead use the REBOOT_VECTOR
3340			irq.
3341
3342	nomodule	Disable module load
3343
3344	nopat		[X86] Disable PAT (page attribute table extension of
3345			pagetables) support.
3346
3347	nopcid		[X86-64] Disable the PCID cpu feature.
3348
3349	norandmaps	Don't use address space randomization.  Equivalent to
3350			echo 0 > /proc/sys/kernel/randomize_va_space
3351
3352	noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
3353			with UP alternatives
3354
3355	nordrand	[X86] Disable kernel use of the RDRAND and
3356			RDSEED instructions even if they are supported
3357			by the processor.  RDRAND and RDSEED are still
3358			available to user space applications.
3359
3360	noresume	[SWSUSP] Disables resume and restores original swap
3361			space.
3362
3363	no-scroll	[VGA] Disables scrollback.
3364			This is required for the Braillex ib80-piezo Braille
3365			reader made by F.H. Papenmeier (Germany).
3366
3367	nosbagart	[IA-64]
3368
3369	nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
3370
3371	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
3372			and disable the IO APIC.  legacy for "maxcpus=0".
3373
3374	nosoftlockup	[KNL] Disable the soft-lockup detector.
3375
3376	nosync		[HW,M68K] Disables sync negotiation for all devices.
3377
3378	nowatchdog	[KNL] Disable both lockup detectors, i.e.
3379			soft-lockup and NMI watchdog (hard-lockup).
3380
3381	nowb		[ARM]
3382
3383	nox2apic	[X86-64,APIC] Do not enable x2APIC mode.
3384
3385	cpu0_hotplug	[X86] Turn on CPU0 hotplug feature when
3386			CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
3387			Some features depend on CPU0. Known dependencies are:
3388			1. Resume from suspend/hibernate depends on CPU0.
3389			Suspend/hibernate will fail if CPU0 is offline and you
3390			need to online CPU0 before suspend/hibernate.
3391			2. PIC interrupts also depend on CPU0. CPU0 can't be
3392			removed if a PIC interrupt is detected.
3393			It's said poweroff/reboot may depend on CPU0 on some
3394			machines although I haven't seen such issues so far
3395			after CPU0 is offline on a few tested machines.
3396			If the dependencies are under your control, you can
3397			turn on cpu0_hotplug.
3398
3399	nps_mtm_hs_ctr=	[KNL,ARC]
3400			This parameter sets the maximum duration, in
3401			cycles, each HW thread of the CTOP can run
3402			without interruptions, before HW switches it.
3403			The actual maximum duration is 16 times this
3404			parameter's value.
3405			Format: integer between 1 and 255
3406			Default: 255
3407
3408	nptcg=		[IA-64] Override max number of concurrent global TLB
3409			purges which is reported from either PAL_VM_SUMMARY or
3410			SAL PALO.
3411
3412	nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
3413			could support.  nr_cpus=n : n >= 1 limits the kernel to
3414			support 'n' processors. It could be larger than the
3415			number of already plugged CPU during bootup, later in
3416			runtime you can physically add extra cpu until it reaches
3417			n. So during boot up some boot time memory for per-cpu
3418			variables need be pre-allocated for later physical cpu
3419			hot plugging.
3420
3421	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
3422
3423	numa_balancing=	[KNL,X86] Enable or disable automatic NUMA balancing.
3424			Allowed values are enable and disable
3425
3426	numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
3427			'node', 'default' can be specified
3428			This can be set from sysctl after boot.
3429			See Documentation/admin-guide/sysctl/vm.rst for details.
3430
3431	ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
3432			See Documentation/core-api/debugging-via-ohci1394.rst for more
3433			info.
3434
3435	olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
3436			Rather than timing out after 20 ms if an EC
3437			command is not properly ACKed, override the length
3438			of the timeout.  We have interrupts disabled while
3439			waiting for the ACK, so if this is set too high
3440			interrupts *may* be lost!
3441
3442	omap_mux=	[OMAP] Override bootloader pin multiplexing.
3443			Format: <mux_mode0.mode_name=value>...
3444			For example, to override I2C bus2:
3445			omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
3446
3447	oprofile.timer=	[HW]
3448			Use timer interrupt instead of performance counters
3449
3450	oprofile.cpu_type=	Force an oprofile cpu type
3451			This might be useful if you have an older oprofile
3452			userland or if you want common events.
3453			Format: { arch_perfmon }
3454			arch_perfmon: [X86] Force use of architectural
3455				perfmon on Intel CPUs instead of the
3456				CPU specific event set.
3457			timer: [X86] Force use of architectural NMI
3458				timer mode (see also oprofile.timer
3459				for generic hr timer mode)
3460
3461	oops=panic	Always panic on oopses. Default is to just kill the
3462			process, but there is a small probability of
3463			deadlocking the machine.
3464			This will also cause panics on machine check exceptions.
3465			Useful together with panic=30 to trigger a reboot.
3466
3467	page_alloc.shuffle=
3468			[KNL] Boolean flag to control whether the page allocator
3469			should randomize its free lists. The randomization may
3470			be automatically enabled if the kernel detects it is
3471			running on a platform with a direct-mapped memory-side
3472			cache, and this parameter can be used to
3473			override/disable that behavior. The state of the flag
3474			can be read from sysfs at:
3475			/sys/module/page_alloc/parameters/shuffle.
3476
3477	page_owner=	[KNL] Boot-time page_owner enabling option.
3478			Storage of the information about who allocated
3479			each page is disabled in default. With this switch,
3480			we can turn it on.
3481			on: enable the feature
3482
3483	page_poison=	[KNL] Boot-time parameter changing the state of
3484			poisoning on the buddy allocator, available with
3485			CONFIG_PAGE_POISONING=y.
3486			off: turn off poisoning (default)
3487			on: turn on poisoning
3488
3489	panic=		[KNL] Kernel behaviour on panic: delay <timeout>
3490			timeout > 0: seconds before rebooting
3491			timeout = 0: wait forever
3492			timeout < 0: reboot immediately
3493			Format: <timeout>
3494
3495	panic_print=	Bitmask for printing system info when panic happens.
3496			User can chose combination of the following bits:
3497			bit 0: print all tasks info
3498			bit 1: print system memory info
3499			bit 2: print timer info
3500			bit 3: print locks info if CONFIG_LOCKDEP is on
3501			bit 4: print ftrace buffer
3502			bit 5: print all printk messages in buffer
3503
3504	panic_on_taint=	Bitmask for conditionally calling panic() in add_taint()
3505			Format: <hex>[,nousertaint]
3506			Hexadecimal bitmask representing the set of TAINT flags
3507			that will cause the kernel to panic when add_taint() is
3508			called with any of the flags in this set.
3509			The optional switch "nousertaint" can be utilized to
3510			prevent userspace forced crashes by writing to sysctl
3511			/proc/sys/kernel/tainted any flagset matching with the
3512			bitmask set on panic_on_taint.
3513			See Documentation/admin-guide/tainted-kernels.rst for
3514			extra details on the taint flags that users can pick
3515			to compose the bitmask to assign to panic_on_taint.
3516
3517	panic_on_warn	panic() instead of WARN().  Useful to cause kdump
3518			on a WARN().
3519
3520	crash_kexec_post_notifiers
3521			Run kdump after running panic-notifiers and dumping
3522			kmsg. This only for the users who doubt kdump always
3523			succeeds in any situation.
3524			Note that this also increases risks of kdump failure,
3525			because some panic notifiers can make the crashed
3526			kernel more unstable.
3527
3528	parkbd.port=	[HW] Parallel port number the keyboard adapter is
3529			connected to, default is 0.
3530			Format: <parport#>
3531	parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
3532			0 for XT, 1 for AT (default is AT).
3533			Format: <mode>
3534
3535	parport=	[HW,PPT] Specify parallel ports. 0 disables.
3536			Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
3537			Use 'auto' to force the driver to use any
3538			IRQ/DMA settings detected (the default is to
3539			ignore detected IRQ/DMA settings because of
3540			possible conflicts). You can specify the base
3541			address, IRQ, and DMA settings; IRQ and DMA
3542			should be numbers, or 'auto' (for using detected
3543			settings on that particular port), or 'nofifo'
3544			(to avoid using a FIFO even if it is detected).
3545			Parallel ports are assigned in the order they
3546			are specified on the command line, starting
3547			with parport0.
3548
3549	parport_init_mode=	[HW,PPT]
3550			Configure VIA parallel port to operate in
3551			a specific mode. This is necessary on Pegasos
3552			computer where firmware has no options for setting
3553			up parallel port mode and sets it to spp.
3554			Currently this function knows 686a and 8231 chips.
3555			Format: [spp|ps2|epp|ecp|ecpepp]
3556
3557	pause_on_oops=
3558			Halt all CPUs after the first oops has been printed for
3559			the specified number of seconds.  This is to be used if
3560			your oopses keep scrolling off the screen.
3561
3562	pcbit=		[HW,ISDN]
3563
3564	pcd.		[PARIDE]
3565			See header of drivers/block/paride/pcd.c.
3566			See also Documentation/admin-guide/blockdev/paride.rst.
3567
3568	pci=option[,option...]	[PCI] various PCI subsystem options.
3569
3570				Some options herein operate on a specific device
3571				or a set of devices (<pci_dev>). These are
3572				specified in one of the following formats:
3573
3574				[<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]*
3575				pci:<vendor>:<device>[:<subvendor>:<subdevice>]
3576
3577				Note: the first format specifies a PCI
3578				bus/device/function address which may change
3579				if new hardware is inserted, if motherboard
3580				firmware changes, or due to changes caused
3581				by other kernel parameters. If the
3582				domain is left unspecified, it is
3583				taken to be zero. Optionally, a path
3584				to a device through multiple device/function
3585				addresses can be specified after the base
3586				address (this is more robust against
3587				renumbering issues).  The second format
3588				selects devices using IDs from the
3589				configuration space which may match multiple
3590				devices in the system.
3591
3592		earlydump	dump PCI config space before the kernel
3593				changes anything
3594		off		[X86] don't probe for the PCI bus
3595		bios		[X86-32] force use of PCI BIOS, don't access
3596				the hardware directly. Use this if your machine
3597				has a non-standard PCI host bridge.
3598		nobios		[X86-32] disallow use of PCI BIOS, only direct
3599				hardware access methods are allowed. Use this
3600				if you experience crashes upon bootup and you
3601				suspect they are caused by the BIOS.
3602		conf1		[X86] Force use of PCI Configuration Access
3603				Mechanism 1 (config address in IO port 0xCF8,
3604				data in IO port 0xCFC, both 32-bit).
3605		conf2		[X86] Force use of PCI Configuration Access
3606				Mechanism 2 (IO port 0xCF8 is an 8-bit port for
3607				the function, IO port 0xCFA, also 8-bit, sets
3608				bus number. The config space is then accessed
3609				through ports 0xC000-0xCFFF).
3610				See http://wiki.osdev.org/PCI for more info
3611				on the configuration access mechanisms.
3612		noaer		[PCIE] If the PCIEAER kernel config parameter is
3613				enabled, this kernel boot option can be used to
3614				disable the use of PCIE advanced error reporting.
3615		nodomains	[PCI] Disable support for multiple PCI
3616				root domains (aka PCI segments, in ACPI-speak).
3617		nommconf	[X86] Disable use of MMCONFIG for PCI
3618				Configuration
3619		check_enable_amd_mmconf [X86] check for and enable
3620				properly configured MMIO access to PCI
3621				config space on AMD family 10h CPU
3622		nomsi		[MSI] If the PCI_MSI kernel config parameter is
3623				enabled, this kernel boot option can be used to
3624				disable the use of MSI interrupts system-wide.
3625		noioapicquirk	[APIC] Disable all boot interrupt quirks.
3626				Safety option to keep boot IRQs enabled. This
3627				should never be necessary.
3628		ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
3629				primary IO-APIC for bridges that cannot disable
3630				boot IRQs. This fixes a source of spurious IRQs
3631				when the system masks IRQs.
3632		noioapicreroute	[APIC] Disable workaround that uses the
3633				boot IRQ equivalent of an IRQ that connects to
3634				a chipset where boot IRQs cannot be disabled.
3635				The opposite of ioapicreroute.
3636		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
3637				routing table. These calls are known to be buggy
3638				on several machines and they hang the machine
3639				when used, but on other computers it's the only
3640				way to get the interrupt routing table. Try
3641				this option if the kernel is unable to allocate
3642				IRQs or discover secondary PCI buses on your
3643				motherboard.
3644		rom		[X86] Assign address space to expansion ROMs.
3645				Use with caution as certain devices share
3646				address decoders between ROMs and other
3647				resources.
3648		norom		[X86] Do not assign address space to
3649				expansion ROMs that do not already have
3650				BIOS assigned address ranges.
3651		nobar		[X86] Do not assign address space to the
3652				BARs that weren't assigned by the BIOS.
3653		irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
3654				assigned automatically to PCI devices. You can
3655				make the kernel exclude IRQs of your ISA cards
3656				this way.
3657		pirqaddr=0xAAAAA	[X86] Specify the physical address
3658				of the PIRQ table (normally generated
3659				by the BIOS) if it is outside the
3660				F0000h-100000h range.
3661		lastbus=N	[X86] Scan all buses thru bus #N. Can be
3662				useful if the kernel is unable to find your
3663				secondary buses and you want to tell it
3664				explicitly which ones they are.
3665		assign-busses	[X86] Always assign all PCI bus
3666				numbers ourselves, overriding
3667				whatever the firmware may have done.
3668		usepirqmask	[X86] Honor the possible IRQ mask stored
3669				in the BIOS $PIR table. This is needed on
3670				some systems with broken BIOSes, notably
3671				some HP Pavilion N5400 and Omnibook XE3
3672				notebooks. This will have no effect if ACPI
3673				IRQ routing is enabled.
3674		noacpi		[X86] Do not use ACPI for IRQ routing
3675				or for PCI scanning.
3676		use_crs		[X86] Use PCI host bridge window information
3677				from ACPI.  On BIOSes from 2008 or later, this
3678				is enabled by default.  If you need to use this,
3679				please report a bug.
3680		nocrs		[X86] Ignore PCI host bridge windows from ACPI.
3681				If you need to use this, please report a bug.
3682		routeirq	Do IRQ routing for all PCI devices.
3683				This is normally done in pci_enable_device(),
3684				so this option is a temporary workaround
3685				for broken drivers that don't call it.
3686		skip_isa_align	[X86] do not align io start addr, so can
3687				handle more pci cards
3688		noearly		[X86] Don't do any early type 1 scanning.
3689				This might help on some broken boards which
3690				machine check when some devices' config space
3691				is read. But various workarounds are disabled
3692				and some IOMMU drivers will not work.
3693		bfsort		Sort PCI devices into breadth-first order.
3694				This sorting is done to get a device
3695				order compatible with older (<= 2.4) kernels.
3696		nobfsort	Don't sort PCI devices into breadth-first order.
3697		pcie_bus_tune_off	Disable PCIe MPS (Max Payload Size)
3698				tuning and use the BIOS-configured MPS defaults.
3699		pcie_bus_safe	Set every device's MPS to the largest value
3700				supported by all devices below the root complex.
3701		pcie_bus_perf	Set device MPS to the largest allowable MPS
3702				based on its parent bus. Also set MRRS (Max
3703				Read Request Size) to the largest supported
3704				value (no larger than the MPS that the device
3705				or bus can support) for best performance.
3706		pcie_bus_peer2peer	Set every device's MPS to 128B, which
3707				every device is guaranteed to support. This
3708				configuration allows peer-to-peer DMA between
3709				any pair of devices, possibly at the cost of
3710				reduced performance.  This also guarantees
3711				that hot-added devices will work.
3712		cbiosize=nn[KMG]	The fixed amount of bus space which is
3713				reserved for the CardBus bridge's IO window.
3714				The default value is 256 bytes.
3715		cbmemsize=nn[KMG]	The fixed amount of bus space which is
3716				reserved for the CardBus bridge's memory
3717				window. The default value is 64 megabytes.
3718		resource_alignment=
3719				Format:
3720				[<order of align>@]<pci_dev>[; ...]
3721				Specifies alignment and device to reassign
3722				aligned memory resources. How to
3723				specify the device is described above.
3724				If <order of align> is not specified,
3725				PAGE_SIZE is used as alignment.
3726				A PCI-PCI bridge can be specified if resource
3727				windows need to be expanded.
3728				To specify the alignment for several
3729				instances of a device, the PCI vendor,
3730				device, subvendor, and subdevice may be
3731				specified, e.g., 12@pci:8086:9c22:103c:198f
3732				for 4096-byte alignment.
3733		ecrc=		Enable/disable PCIe ECRC (transaction layer
3734				end-to-end CRC checking).
3735				bios: Use BIOS/firmware settings. This is the
3736				the default.
3737				off: Turn ECRC off
3738				on: Turn ECRC on.
3739		hpiosize=nn[KMG]	The fixed amount of bus space which is
3740				reserved for hotplug bridge's IO window.
3741				Default size is 256 bytes.
3742		hpmmiosize=nn[KMG]	The fixed amount of bus space which is
3743				reserved for hotplug bridge's MMIO window.
3744				Default size is 2 megabytes.
3745		hpmmioprefsize=nn[KMG]	The fixed amount of bus space which is
3746				reserved for hotplug bridge's MMIO_PREF window.
3747				Default size is 2 megabytes.
3748		hpmemsize=nn[KMG]	The fixed amount of bus space which is
3749				reserved for hotplug bridge's MMIO and
3750				MMIO_PREF window.
3751				Default size is 2 megabytes.
3752		hpbussize=nn	The minimum amount of additional bus numbers
3753				reserved for buses below a hotplug bridge.
3754				Default is 1.
3755		realloc=	Enable/disable reallocating PCI bridge resources
3756				if allocations done by BIOS are too small to
3757				accommodate resources required by all child
3758				devices.
3759				off: Turn realloc off
3760				on: Turn realloc on
3761		realloc		same as realloc=on
3762		noari		do not use PCIe ARI.
3763		noats		[PCIE, Intel-IOMMU, AMD-IOMMU]
3764				do not use PCIe ATS (and IOMMU device IOTLB).
3765		pcie_scan_all	Scan all possible PCIe devices.  Otherwise we
3766				only look for one device below a PCIe downstream
3767				port.
3768		big_root_window	Try to add a big 64bit memory window to the PCIe
3769				root complex on AMD CPUs. Some GFX hardware
3770				can resize a BAR to allow access to all VRAM.
3771				Adding the window is slightly risky (it may
3772				conflict with unreported devices), so this
3773				taints the kernel.
3774		disable_acs_redir=<pci_dev>[; ...]
3775				Specify one or more PCI devices (in the format
3776				specified above) separated by semicolons.
3777				Each device specified will have the PCI ACS
3778				redirect capabilities forced off which will
3779				allow P2P traffic between devices through
3780				bridges without forcing it upstream. Note:
3781				this removes isolation between devices and
3782				may put more devices in an IOMMU group.
3783		force_floating	[S390] Force usage of floating interrupts.
3784		nomio		[S390] Do not use MIO instructions.
3785		norid		[S390] ignore the RID field and force use of
3786				one PCI domain per PCI function
3787
3788	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
3789			Management.
3790		off	Disable ASPM.
3791		force	Enable ASPM even on devices that claim not to support it.
3792			WARNING: Forcing ASPM on may cause system lockups.
3793
3794	pcie_ports=	[PCIE] PCIe port services handling:
3795		native	Use native PCIe services (PME, AER, DPC, PCIe hotplug)
3796			even if the platform doesn't give the OS permission to
3797			use them.  This may cause conflicts if the platform
3798			also tries to use these services.
3799		dpc-native	Use native PCIe service for DPC only.  May
3800				cause conflicts if firmware uses AER or DPC.
3801		compat	Disable native PCIe services (PME, AER, DPC, PCIe
3802			hotplug).
3803
3804	pcie_port_pm=	[PCIE] PCIe port power management handling:
3805		off	Disable power management of all PCIe ports
3806		force	Forcibly enable power management of all PCIe ports
3807
3808	pcie_pme=	[PCIE,PM] Native PCIe PME signaling options:
3809		nomsi	Do not use MSI for native PCIe PME signaling (this makes
3810			all PCIe root ports use INTx for all services).
3811
3812	pcmv=		[HW,PCMCIA] BadgePAD 4
3813
3814	pd_ignore_unused
3815			[PM]
3816			Keep all power-domains already enabled by bootloader on,
3817			even if no driver has claimed them. This is useful
3818			for debug and development, but should not be
3819			needed on a platform with proper driver support.
3820
3821	pd.		[PARIDE]
3822			See Documentation/admin-guide/blockdev/paride.rst.
3823
3824	pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
3825			boot time.
3826			Format: { 0 | 1 }
3827			See arch/parisc/kernel/pdc_chassis.c
3828
3829	percpu_alloc=	Select which percpu first chunk allocator to use.
3830			Currently supported values are "embed" and "page".
3831			Archs may support subset or none of the	selections.
3832			See comments in mm/percpu.c for details on each
3833			allocator.  This parameter is primarily	for debugging
3834			and performance comparison.
3835
3836	pf.		[PARIDE]
3837			See Documentation/admin-guide/blockdev/paride.rst.
3838
3839	pg.		[PARIDE]
3840			See Documentation/admin-guide/blockdev/paride.rst.
3841
3842	pirq=		[SMP,APIC] Manual mp-table setup
3843			See Documentation/x86/i386/IO-APIC.rst.
3844
3845	plip=		[PPT,NET] Parallel port network link
3846			Format: { parport<nr> | timid | 0 }
3847			See also Documentation/admin-guide/parport.rst.
3848
3849	pmtmr=		[X86] Manual setup of pmtmr I/O Port.
3850			Override pmtimer IOPort with a hex value.
3851			e.g. pmtmr=0x508
3852
3853	pm_debug_messages	[SUSPEND,KNL]
3854			Enable suspend/resume debug messages during boot up.
3855
3856	pnp.debug=1	[PNP]
3857			Enable PNP debug messages (depends on the
3858			CONFIG_PNP_DEBUG_MESSAGES option).  Change at run-time
3859			via /sys/module/pnp/parameters/debug.  We always show
3860			current resource usage; turning this on also shows
3861			possible settings and some assignment information.
3862
3863	pnpacpi=	[ACPI]
3864			{ off }
3865
3866	pnpbios=	[ISAPNP]
3867			{ on | off | curr | res | no-curr | no-res }
3868
3869	pnp_reserve_irq=
3870			[ISAPNP] Exclude IRQs for the autoconfiguration
3871
3872	pnp_reserve_dma=
3873			[ISAPNP] Exclude DMAs for the autoconfiguration
3874
3875	pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
3876			Ranges are in pairs (I/O port base and size).
3877
3878	pnp_reserve_mem=
3879			[ISAPNP] Exclude memory regions for the
3880			autoconfiguration.
3881			Ranges are in pairs (memory base and size).
3882
3883	ports=		[IP_VS_FTP] IPVS ftp helper module
3884			Default is 21.
3885			Up to 8 (IP_VS_APP_MAX_PORTS) ports
3886			may be specified.
3887			Format: <port>,<port>....
3888
3889	powersave=off	[PPC] This option disables power saving features.
3890			It specifically disables cpuidle and sets the
3891			platform machine description specific power_save
3892			function to NULL. On Idle the CPU just reduces
3893			execution priority.
3894
3895	ppc_strict_facility_enable
3896			[PPC] This option catches any kernel floating point,
3897			Altivec, VSX and SPE outside of regions specifically
3898			allowed (eg kernel_enable_fpu()/kernel_disable_fpu()).
3899			There is some performance impact when enabling this.
3900
3901	ppc_tm=		[PPC]
3902			Format: {"off"}
3903			Disable Hardware Transactional Memory
3904
3905	print-fatal-signals=
3906			[KNL] debug: print fatal signals
3907
3908			If enabled, warn about various signal handling
3909			related application anomalies: too many signals,
3910			too many POSIX.1 timers, fatal signals causing a
3911			coredump - etc.
3912
3913			If you hit the warning due to signal overflow,
3914			you might want to try "ulimit -i unlimited".
3915
3916			default: off.
3917
3918	printk.always_kmsg_dump=
3919			Trigger kmsg_dump for cases other than kernel oops or
3920			panics
3921			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
3922			default: disabled
3923
3924	printk.devkmsg={on,off,ratelimit}
3925			Control writing to /dev/kmsg.
3926			on - unlimited logging to /dev/kmsg from userspace
3927			off - logging to /dev/kmsg disabled
3928			ratelimit - ratelimit the logging
3929			Default: ratelimit
3930
3931	printk.time=	Show timing data prefixed to each printk message line
3932			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
3933
3934	processor.max_cstate=	[HW,ACPI]
3935			Limit processor to maximum C-state
3936			max_cstate=9 overrides any DMI blacklist limit.
3937
3938	processor.nocst	[HW,ACPI]
3939			Ignore the _CST method to determine C-states,
3940			instead using the legacy FADT method
3941
3942	profile=	[KNL] Enable kernel profiling via /proc/profile
3943			Format: [<profiletype>,]<number>
3944			Param: <profiletype>: "schedule", "sleep", or "kvm"
3945				[defaults to kernel profiling]
3946			Param: "schedule" - profile schedule points.
3947			Param: "sleep" - profile D-state sleeping (millisecs).
3948				Requires CONFIG_SCHEDSTATS
3949			Param: "kvm" - profile VM exits.
3950			Param: <number> - step/bucket size as a power of 2 for
3951				statistical time based profiling.
3952
3953	prompt_ramdisk=	[RAM] [Deprecated]
3954
3955	prot_virt=	[S390] enable hosting protected virtual machines
3956			isolated from the hypervisor (if hardware supports
3957			that).
3958			Format: <bool>
3959
3960	psi=		[KNL] Enable or disable pressure stall information
3961			tracking.
3962			Format: <bool>
3963
3964	psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
3965			probe for; one of (bare|imps|exps|lifebook|any).
3966	psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
3967			per second.
3968	psmouse.resetafter=	[HW,MOUSE]
3969			Try to reset the device after so many bad packets
3970			(0 = never).
3971	psmouse.resolution=
3972			[HW,MOUSE] Set desired mouse resolution, in dpi.
3973	psmouse.smartscroll=
3974			[HW,MOUSE] Controls Logitech smartscroll autorepeat.
3975			0 = disabled, 1 = enabled (default).
3976
3977	pstore.backend=	Specify the name of the pstore backend to use
3978
3979	pt.		[PARIDE]
3980			See Documentation/admin-guide/blockdev/paride.rst.
3981
3982	pti=		[X86-64] Control Page Table Isolation of user and
3983			kernel address spaces.  Disabling this feature
3984			removes hardening, but improves performance of
3985			system calls and interrupts.
3986
3987			on   - unconditionally enable
3988			off  - unconditionally disable
3989			auto - kernel detects whether your CPU model is
3990			       vulnerable to issues that PTI mitigates
3991
3992			Not specifying this option is equivalent to pti=auto.
3993
3994	nopti		[X86-64]
3995			Equivalent to pti=off
3996
3997	pty.legacy_count=
3998			[KNL] Number of legacy pty's. Overwrites compiled-in
3999			default number.
4000
4001	quiet		[KNL] Disable most log messages
4002
4003	r128=		[HW,DRM]
4004
4005	raid=		[HW,RAID]
4006			See Documentation/admin-guide/md.rst.
4007
4008	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
4009			See Documentation/admin-guide/blockdev/ramdisk.rst.
4010
4011	ramdisk_start=	[RAM] RAM disk image start address
4012
4013	random.trust_cpu={on,off}
4014			[KNL] Enable or disable trusting the use of the
4015			CPU's random number generator (if available) to
4016			fully seed the kernel's CRNG. Default is controlled
4017			by CONFIG_RANDOM_TRUST_CPU.
4018
4019	ras=option[,option,...]	[KNL] RAS-specific options
4020
4021		cec_disable	[X86]
4022				Disable the Correctable Errors Collector,
4023				see CONFIG_RAS_CEC help text.
4024
4025	rcu_nocbs=	[KNL]
4026			The argument is a cpu list, as described above,
4027			except that the string "all" can be used to
4028			specify every CPU on the system.
4029
4030			In kernels built with CONFIG_RCU_NOCB_CPU=y, set
4031			the specified list of CPUs to be no-callback CPUs.
4032			Invocation of these CPUs' RCU callbacks will be
4033			offloaded to "rcuox/N" kthreads created for that
4034			purpose, where "x" is "p" for RCU-preempt, and
4035			"s" for RCU-sched, and "N" is the CPU number.
4036			This reduces OS jitter on the offloaded CPUs,
4037			which can be useful for HPC and real-time
4038			workloads.  It can also improve energy efficiency
4039			for asymmetric multiprocessors.
4040
4041	rcu_nocb_poll	[KNL]
4042			Rather than requiring that offloaded CPUs
4043			(specified by rcu_nocbs= above) explicitly
4044			awaken the corresponding "rcuoN" kthreads,
4045			make these kthreads poll for callbacks.
4046			This improves the real-time response for the
4047			offloaded CPUs by relieving them of the need to
4048			wake up the corresponding kthread, but degrades
4049			energy efficiency by requiring that the kthreads
4050			periodically wake up to do the polling.
4051
4052	rcutree.blimit=	[KNL]
4053			Set maximum number of finished RCU callbacks to
4054			process in one batch.
4055
4056	rcutree.dump_tree=	[KNL]
4057			Dump the structure of the rcu_node combining tree
4058			out at early boot.  This is used for diagnostic
4059			purposes, to verify correct tree setup.
4060
4061	rcutree.gp_cleanup_delay=	[KNL]
4062			Set the number of jiffies to delay each step of
4063			RCU grace-period cleanup.
4064
4065	rcutree.gp_init_delay=	[KNL]
4066			Set the number of jiffies to delay each step of
4067			RCU grace-period initialization.
4068
4069	rcutree.gp_preinit_delay=	[KNL]
4070			Set the number of jiffies to delay each step of
4071			RCU grace-period pre-initialization, that is,
4072			the propagation of recent CPU-hotplug changes up
4073			the rcu_node combining tree.
4074
4075	rcutree.use_softirq=	[KNL]
4076			If set to zero, move all RCU_SOFTIRQ processing to
4077			per-CPU rcuc kthreads.  Defaults to a non-zero
4078			value, meaning that RCU_SOFTIRQ is used by default.
4079			Specify rcutree.use_softirq=0 to use rcuc kthreads.
4080
4081	rcutree.rcu_fanout_exact= [KNL]
4082			Disable autobalancing of the rcu_node combining
4083			tree.  This is used by rcutorture, and might
4084			possibly be useful for architectures having high
4085			cache-to-cache transfer latencies.
4086
4087	rcutree.rcu_fanout_leaf= [KNL]
4088			Change the number of CPUs assigned to each
4089			leaf rcu_node structure.  Useful for very
4090			large systems, which will choose the value 64,
4091			and for NUMA systems with large remote-access
4092			latencies, which will choose a value aligned
4093			with the appropriate hardware boundaries.
4094
4095	rcutree.rcu_min_cached_objs= [KNL]
4096			Minimum number of objects which are cached and
4097			maintained per one CPU. Object size is equal
4098			to PAGE_SIZE. The cache allows to reduce the
4099			pressure to page allocator, also it makes the
4100			whole algorithm to behave better in low memory
4101			condition.
4102
4103	rcutree.jiffies_till_first_fqs= [KNL]
4104			Set delay from grace-period initialization to
4105			first attempt to force quiescent states.
4106			Units are jiffies, minimum value is zero,
4107			and maximum value is HZ.
4108
4109	rcutree.jiffies_till_next_fqs= [KNL]
4110			Set delay between subsequent attempts to force
4111			quiescent states.  Units are jiffies, minimum
4112			value is one, and maximum value is HZ.
4113
4114	rcutree.jiffies_till_sched_qs= [KNL]
4115			Set required age in jiffies for a
4116			given grace period before RCU starts
4117			soliciting quiescent-state help from
4118			rcu_note_context_switch() and cond_resched().
4119			If not specified, the kernel will calculate
4120			a value based on the most recent settings
4121			of rcutree.jiffies_till_first_fqs
4122			and rcutree.jiffies_till_next_fqs.
4123			This calculated value may be viewed in
4124			rcutree.jiffies_to_sched_qs.  Any attempt to set
4125			rcutree.jiffies_to_sched_qs will be cheerfully
4126			overwritten.
4127
4128	rcutree.kthread_prio= 	 [KNL,BOOT]
4129			Set the SCHED_FIFO priority of the RCU per-CPU
4130			kthreads (rcuc/N). This value is also used for
4131			the priority of the RCU boost threads (rcub/N)
4132			and for the RCU grace-period kthreads (rcu_bh,
4133			rcu_preempt, and rcu_sched). If RCU_BOOST is
4134			set, valid values are 1-99 and the default is 1
4135			(the least-favored priority).  Otherwise, when
4136			RCU_BOOST is not set, valid values are 0-99 and
4137			the default is zero (non-realtime operation).
4138
4139	rcutree.rcu_nocb_gp_stride= [KNL]
4140			Set the number of NOCB callback kthreads in
4141			each group, which defaults to the square root
4142			of the number of CPUs.	Larger numbers reduce
4143			the wakeup overhead on the global grace-period
4144			kthread, but increases that same overhead on
4145			each group's NOCB grace-period kthread.
4146
4147	rcutree.qhimark= [KNL]
4148			Set threshold of queued RCU callbacks beyond which
4149			batch limiting is disabled.
4150
4151	rcutree.qlowmark= [KNL]
4152			Set threshold of queued RCU callbacks below which
4153			batch limiting is re-enabled.
4154
4155	rcutree.qovld= [KNL]
4156			Set threshold of queued RCU callbacks beyond which
4157			RCU's force-quiescent-state scan will aggressively
4158			enlist help from cond_resched() and sched IPIs to
4159			help CPUs more quickly reach quiescent states.
4160			Set to less than zero to make this be set based
4161			on rcutree.qhimark at boot time and to zero to
4162			disable more aggressive help enlistment.
4163
4164	rcutree.rcu_idle_gp_delay= [KNL]
4165			Set wakeup interval for idle CPUs that have
4166			RCU callbacks (RCU_FAST_NO_HZ=y).
4167
4168	rcutree.rcu_idle_lazy_gp_delay= [KNL]
4169			Set wakeup interval for idle CPUs that have
4170			only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
4171			Lazy RCU callbacks are those which RCU can
4172			prove do nothing more than free memory.
4173
4174	rcutree.rcu_kick_kthreads= [KNL]
4175			Cause the grace-period kthread to get an extra
4176			wake_up() if it sleeps three times longer than
4177			it should at force-quiescent-state time.
4178			This wake_up() will be accompanied by a
4179			WARN_ONCE() splat and an ftrace_dump().
4180
4181	rcutree.rcu_unlock_delay= [KNL]
4182			In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels,
4183			this specifies an rcu_read_unlock()-time delay
4184			in microseconds.  This defaults to zero.
4185			Larger delays increase the probability of
4186			catching RCU pointer leaks, that is, buggy use
4187			of RCU-protected pointers after the relevant
4188			rcu_read_unlock() has completed.
4189
4190	rcutree.sysrq_rcu= [KNL]
4191			Commandeer a sysrq key to dump out Tree RCU's
4192			rcu_node tree with an eye towards determining
4193			why a new grace period has not yet started.
4194
4195	rcuscale.gp_async= [KNL]
4196			Measure performance of asynchronous
4197			grace-period primitives such as call_rcu().
4198
4199	rcuscale.gp_async_max= [KNL]
4200			Specify the maximum number of outstanding
4201			callbacks per writer thread.  When a writer
4202			thread exceeds this limit, it invokes the
4203			corresponding flavor of rcu_barrier() to allow
4204			previously posted callbacks to drain.
4205
4206	rcuscale.gp_exp= [KNL]
4207			Measure performance of expedited synchronous
4208			grace-period primitives.
4209
4210	rcuscale.holdoff= [KNL]
4211			Set test-start holdoff period.  The purpose of
4212			this parameter is to delay the start of the
4213			test until boot completes in order to avoid
4214			interference.
4215
4216	rcuscale.kfree_rcu_test= [KNL]
4217			Set to measure performance of kfree_rcu() flooding.
4218
4219	rcuscale.kfree_nthreads= [KNL]
4220			The number of threads running loops of kfree_rcu().
4221
4222	rcuscale.kfree_alloc_num= [KNL]
4223			Number of allocations and frees done in an iteration.
4224
4225	rcuscale.kfree_loops= [KNL]
4226			Number of loops doing rcuscale.kfree_alloc_num number
4227			of allocations and frees.
4228
4229	rcuscale.nreaders= [KNL]
4230			Set number of RCU readers.  The value -1 selects
4231			N, where N is the number of CPUs.  A value
4232			"n" less than -1 selects N-n+1, where N is again
4233			the number of CPUs.  For example, -2 selects N
4234			(the number of CPUs), -3 selects N+1, and so on.
4235			A value of "n" less than or equal to -N selects
4236			a single reader.
4237
4238	rcuscale.nwriters= [KNL]
4239			Set number of RCU writers.  The values operate
4240			the same as for rcuscale.nreaders.
4241			N, where N is the number of CPUs
4242
4243	rcuscale.perf_type= [KNL]
4244			Specify the RCU implementation to test.
4245
4246	rcuscale.shutdown= [KNL]
4247			Shut the system down after performance tests
4248			complete.  This is useful for hands-off automated
4249			testing.
4250
4251	rcuscale.verbose= [KNL]
4252			Enable additional printk() statements.
4253
4254	rcuscale.writer_holdoff= [KNL]
4255			Write-side holdoff between grace periods,
4256			in microseconds.  The default of zero says
4257			no holdoff.
4258
4259	rcutorture.fqs_duration= [KNL]
4260			Set duration of force_quiescent_state bursts
4261			in microseconds.
4262
4263	rcutorture.fqs_holdoff= [KNL]
4264			Set holdoff time within force_quiescent_state bursts
4265			in microseconds.
4266
4267	rcutorture.fqs_stutter= [KNL]
4268			Set wait time between force_quiescent_state bursts
4269			in seconds.
4270
4271	rcutorture.fwd_progress= [KNL]
4272			Enable RCU grace-period forward-progress testing
4273			for the types of RCU supporting this notion.
4274
4275	rcutorture.fwd_progress_div= [KNL]
4276			Specify the fraction of a CPU-stall-warning
4277			period to do tight-loop forward-progress testing.
4278
4279	rcutorture.fwd_progress_holdoff= [KNL]
4280			Number of seconds to wait between successive
4281			forward-progress tests.
4282
4283	rcutorture.fwd_progress_need_resched= [KNL]
4284			Enclose cond_resched() calls within checks for
4285			need_resched() during tight-loop forward-progress
4286			testing.
4287
4288	rcutorture.gp_cond= [KNL]
4289			Use conditional/asynchronous update-side
4290			primitives, if available.
4291
4292	rcutorture.gp_exp= [KNL]
4293			Use expedited update-side primitives, if available.
4294
4295	rcutorture.gp_normal= [KNL]
4296			Use normal (non-expedited) asynchronous
4297			update-side primitives, if available.
4298
4299	rcutorture.gp_sync= [KNL]
4300			Use normal (non-expedited) synchronous
4301			update-side primitives, if available.  If all
4302			of rcutorture.gp_cond=, rcutorture.gp_exp=,
4303			rcutorture.gp_normal=, and rcutorture.gp_sync=
4304			are zero, rcutorture acts as if is interpreted
4305			they are all non-zero.
4306
4307	rcutorture.irqreader= [KNL]
4308			Run RCU readers from irq handlers, or, more
4309			accurately, from a timer handler.  Not all RCU
4310			flavors take kindly to this sort of thing.
4311
4312	rcutorture.leakpointer= [KNL]
4313			Leak an RCU-protected pointer out of the reader.
4314			This can of course result in splats, and is
4315			intended to test the ability of things like
4316			CONFIG_RCU_STRICT_GRACE_PERIOD=y to detect
4317			such leaks.
4318
4319	rcutorture.n_barrier_cbs= [KNL]
4320			Set callbacks/threads for rcu_barrier() testing.
4321
4322	rcutorture.nfakewriters= [KNL]
4323			Set number of concurrent RCU writers.  These just
4324			stress RCU, they don't participate in the actual
4325			test, hence the "fake".
4326
4327	rcutorture.nreaders= [KNL]
4328			Set number of RCU readers.  The value -1 selects
4329			N-1, where N is the number of CPUs.  A value
4330			"n" less than -1 selects N-n-2, where N is again
4331			the number of CPUs.  For example, -2 selects N
4332			(the number of CPUs), -3 selects N+1, and so on.
4333
4334	rcutorture.object_debug= [KNL]
4335			Enable debug-object double-call_rcu() testing.
4336
4337	rcutorture.onoff_holdoff= [KNL]
4338			Set time (s) after boot for CPU-hotplug testing.
4339
4340	rcutorture.onoff_interval= [KNL]
4341			Set time (jiffies) between CPU-hotplug operations,
4342			or zero to disable CPU-hotplug testing.
4343
4344	rcutorture.read_exit= [KNL]
4345			Set the number of read-then-exit kthreads used
4346			to test the interaction of RCU updaters and
4347			task-exit processing.
4348
4349	rcutorture.read_exit_burst= [KNL]
4350			The number of times in a given read-then-exit
4351			episode that a set of read-then-exit kthreads
4352			is spawned.
4353
4354	rcutorture.read_exit_delay= [KNL]
4355			The delay, in seconds, between successive
4356			read-then-exit testing episodes.
4357
4358	rcutorture.shuffle_interval= [KNL]
4359			Set task-shuffle interval (s).  Shuffling tasks
4360			allows some CPUs to go into dyntick-idle mode
4361			during the rcutorture test.
4362
4363	rcutorture.shutdown_secs= [KNL]
4364			Set time (s) after boot system shutdown.  This
4365			is useful for hands-off automated testing.
4366
4367	rcutorture.stall_cpu= [KNL]
4368			Duration of CPU stall (s) to test RCU CPU stall
4369			warnings, zero to disable.
4370
4371	rcutorture.stall_cpu_block= [KNL]
4372			Sleep while stalling if set.  This will result
4373			in warnings from preemptible RCU in addition
4374			to any other stall-related activity.
4375
4376	rcutorture.stall_cpu_holdoff= [KNL]
4377			Time to wait (s) after boot before inducing stall.
4378
4379	rcutorture.stall_cpu_irqsoff= [KNL]
4380			Disable interrupts while stalling if set.
4381
4382	rcutorture.stall_gp_kthread= [KNL]
4383			Duration (s) of forced sleep within RCU
4384			grace-period kthread to test RCU CPU stall
4385			warnings, zero to disable.  If both stall_cpu
4386			and stall_gp_kthread are specified, the
4387			kthread is starved first, then the CPU.
4388
4389	rcutorture.stat_interval= [KNL]
4390			Time (s) between statistics printk()s.
4391
4392	rcutorture.stutter= [KNL]
4393			Time (s) to stutter testing, for example, specifying
4394			five seconds causes the test to run for five seconds,
4395			wait for five seconds, and so on.  This tests RCU's
4396			ability to transition abruptly to and from idle.
4397
4398	rcutorture.test_boost= [KNL]
4399			Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
4400			"Maybe" means test if the RCU implementation
4401			under test support RCU priority boosting.
4402
4403	rcutorture.test_boost_duration= [KNL]
4404			Duration (s) of each individual boost test.
4405
4406	rcutorture.test_boost_interval= [KNL]
4407			Interval (s) between each boost test.
4408
4409	rcutorture.test_no_idle_hz= [KNL]
4410			Test RCU's dyntick-idle handling.  See also the
4411			rcutorture.shuffle_interval parameter.
4412
4413	rcutorture.torture_type= [KNL]
4414			Specify the RCU implementation to test.
4415
4416	rcutorture.verbose= [KNL]
4417			Enable additional printk() statements.
4418
4419	rcupdate.rcu_cpu_stall_ftrace_dump= [KNL]
4420			Dump ftrace buffer after reporting RCU CPU
4421			stall warning.
4422
4423	rcupdate.rcu_cpu_stall_suppress= [KNL]
4424			Suppress RCU CPU stall warning messages.
4425
4426	rcupdate.rcu_cpu_stall_suppress_at_boot= [KNL]
4427			Suppress RCU CPU stall warning messages and
4428			rcutorture writer stall warnings that occur
4429			during early boot, that is, during the time
4430			before the init task is spawned.
4431
4432	rcupdate.rcu_cpu_stall_timeout= [KNL]
4433			Set timeout for RCU CPU stall warning messages.
4434
4435	rcupdate.rcu_expedited= [KNL]
4436			Use expedited grace-period primitives, for
4437			example, synchronize_rcu_expedited() instead
4438			of synchronize_rcu().  This reduces latency,
4439			but can increase CPU utilization, degrade
4440			real-time latency, and degrade energy efficiency.
4441			No effect on CONFIG_TINY_RCU kernels.
4442
4443	rcupdate.rcu_normal= [KNL]
4444			Use only normal grace-period primitives,
4445			for example, synchronize_rcu() instead of
4446			synchronize_rcu_expedited().  This improves
4447			real-time latency, CPU utilization, and
4448			energy efficiency, but can expose users to
4449			increased grace-period latency.  This parameter
4450			overrides rcupdate.rcu_expedited.  No effect on
4451			CONFIG_TINY_RCU kernels.
4452
4453	rcupdate.rcu_normal_after_boot= [KNL]
4454			Once boot has completed (that is, after
4455			rcu_end_inkernel_boot() has been invoked), use
4456			only normal grace-period primitives.  No effect
4457			on CONFIG_TINY_RCU kernels.
4458
4459	rcupdate.rcu_task_ipi_delay= [KNL]
4460			Set time in jiffies during which RCU tasks will
4461			avoid sending IPIs, starting with the beginning
4462			of a given grace period.  Setting a large
4463			number avoids disturbing real-time workloads,
4464			but lengthens grace periods.
4465
4466	rcupdate.rcu_task_stall_timeout= [KNL]
4467			Set timeout in jiffies for RCU task stall warning
4468			messages.  Disable with a value less than or equal
4469			to zero.
4470
4471	rcupdate.rcu_self_test= [KNL]
4472			Run the RCU early boot self tests
4473
4474	rdinit=		[KNL]
4475			Format: <full_path>
4476			Run specified binary instead of /init from the ramdisk,
4477			used for early userspace startup. See initrd.
4478
4479	rdrand=		[X86]
4480			force - Override the decision by the kernel to hide the
4481				advertisement of RDRAND support (this affects
4482				certain AMD processors because of buggy BIOS
4483				support, specifically around the suspend/resume
4484				path).
4485
4486	rdt=		[HW,X86,RDT]
4487			Turn on/off individual RDT features. List is:
4488			cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
4489			mba.
4490			E.g. to turn on cmt and turn off mba use:
4491				rdt=cmt,!mba
4492
4493	reboot=		[KNL]
4494			Format (x86 or x86_64):
4495				[w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
4496				[[,]s[mp]#### \
4497				[[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
4498				[[,]f[orce]
4499			Where reboot_mode is one of warm (soft) or cold (hard) or gpio
4500					(prefix with 'panic_' to set mode for panic
4501					reboot only),
4502			      reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
4503			      reboot_force is either force or not specified,
4504			      reboot_cpu is s[mp]#### with #### being the processor
4505					to be used for rebooting.
4506
4507	refscale.holdoff= [KNL]
4508			Set test-start holdoff period.  The purpose of
4509			this parameter is to delay the start of the
4510			test until boot completes in order to avoid
4511			interference.
4512
4513	refscale.loops= [KNL]
4514			Set the number of loops over the synchronization
4515			primitive under test.  Increasing this number
4516			reduces noise due to loop start/end overhead,
4517			but the default has already reduced the per-pass
4518			noise to a handful of picoseconds on ca. 2020
4519			x86 laptops.
4520
4521	refscale.nreaders= [KNL]
4522			Set number of readers.  The default value of -1
4523			selects N, where N is roughly 75% of the number
4524			of CPUs.  A value of zero is an interesting choice.
4525
4526	refscale.nruns= [KNL]
4527			Set number of runs, each of which is dumped onto
4528			the console log.
4529
4530	refscale.readdelay= [KNL]
4531			Set the read-side critical-section duration,
4532			measured in microseconds.
4533
4534	refscale.scale_type= [KNL]
4535			Specify the read-protection implementation to test.
4536
4537	refscale.shutdown= [KNL]
4538			Shut down the system at the end of the performance
4539			test.  This defaults to 1 (shut it down) when
4540			refscale is built into the kernel and to 0 (leave
4541			it running) when refscale is built as a module.
4542
4543	refscale.verbose= [KNL]
4544			Enable additional printk() statements.
4545
4546	relax_domain_level=
4547			[KNL, SMP] Set scheduler's default relax_domain_level.
4548			See Documentation/admin-guide/cgroup-v1/cpusets.rst.
4549
4550	reserve=	[KNL,BUGS] Force kernel to ignore I/O ports or memory
4551			Format: <base1>,<size1>[,<base2>,<size2>,...]
4552			Reserve I/O ports or memory so the kernel won't use
4553			them.  If <base> is less than 0x10000, the region
4554			is assumed to be I/O ports; otherwise it is memory.
4555
4556	reservetop=	[X86-32]
4557			Format: nn[KMG]
4558			Reserves a hole at the top of the kernel virtual
4559			address space.
4560
4561	reservelow=	[X86]
4562			Format: nn[K]
4563			Set the amount of memory to reserve for BIOS at
4564			the bottom of the address space.
4565
4566	reset_devices	[KNL] Force drivers to reset the underlying device
4567			during initialization.
4568
4569	resume=		[SWSUSP]
4570			Specify the partition device for software suspend
4571			Format:
4572			{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
4573
4574	resume_offset=	[SWSUSP]
4575			Specify the offset from the beginning of the partition
4576			given by "resume=" at which the swap header is located,
4577			in <PAGE_SIZE> units (needed only for swap files).
4578			See  Documentation/power/swsusp-and-swap-files.rst
4579
4580	resumedelay=	[HIBERNATION] Delay (in seconds) to pause before attempting to
4581			read the resume files
4582
4583	resumewait	[HIBERNATION] Wait (indefinitely) for resume device to show up.
4584			Useful for devices that are detected asynchronously
4585			(e.g. USB and MMC devices).
4586
4587	hibernate=	[HIBERNATION]
4588		noresume	Don't check if there's a hibernation image
4589				present during boot.
4590		nocompress	Don't compress/decompress hibernation images.
4591		no		Disable hibernation and resume.
4592		protect_image	Turn on image protection during restoration
4593				(that will set all pages holding image data
4594				during restoration read-only).
4595
4596	retain_initrd	[RAM] Keep initrd memory after extraction
4597
4598	rfkill.default_state=
4599		0	"airplane mode".  All wifi, bluetooth, wimax, gps, fm,
4600			etc. communication is blocked by default.
4601		1	Unblocked.
4602
4603	rfkill.master_switch_mode=
4604		0	The "airplane mode" button does nothing.
4605		1	The "airplane mode" button toggles between everything
4606			blocked and the previous configuration.
4607		2	The "airplane mode" button toggles between everything
4608			blocked and everything unblocked.
4609
4610	rhash_entries=	[KNL,NET]
4611			Set number of hash buckets for route cache
4612
4613	ring3mwait=disable
4614			[KNL] Disable ring 3 MONITOR/MWAIT feature on supported
4615			CPUs.
4616
4617	ro		[KNL] Mount root device read-only on boot
4618
4619	rodata=		[KNL]
4620		on	Mark read-only kernel memory as read-only (default).
4621		off	Leave read-only kernel memory writable for debugging.
4622
4623	rockchip.usb_uart
4624			Enable the uart passthrough on the designated usb port
4625			on Rockchip SoCs. When active, the signals of the
4626			debug-uart get routed to the D+ and D- pins of the usb
4627			port and the regular usb controller gets disabled.
4628
4629	root=		[KNL] Root filesystem
4630			See name_to_dev_t comment in init/do_mounts.c.
4631
4632	rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
4633			mount the root filesystem
4634
4635	rootflags=	[KNL] Set root filesystem mount option string
4636
4637	rootfstype=	[KNL] Set root filesystem type
4638
4639	rootwait	[KNL] Wait (indefinitely) for root device to show up.
4640			Useful for devices that are detected asynchronously
4641			(e.g. USB and MMC devices).
4642
4643	rproc_mem=nn[KMG][@address]
4644			[KNL,ARM,CMA] Remoteproc physical memory block.
4645			Memory area to be used by remote processor image,
4646			managed by CMA.
4647
4648	rw		[KNL] Mount root device read-write on boot
4649
4650	S		[KNL] Run init in single mode
4651
4652	s390_iommu=	[HW,S390]
4653			Set s390 IOTLB flushing mode
4654		strict
4655			With strict flushing every unmap operation will result in
4656			an IOTLB flush. Default is lazy flushing before reuse,
4657			which is faster.
4658
4659	sa1100ir	[NET]
4660			See drivers/net/irda/sa1100_ir.c.
4661
4662	sbni=		[NET] Granch SBNI12 leased line adapter
4663
4664	sched_debug	[KNL] Enables verbose scheduler debug messages.
4665
4666	schedstats=	[KNL,X86] Enable or disable scheduled statistics.
4667			Allowed values are enable and disable. This feature
4668			incurs a small amount of overhead in the scheduler
4669			but is useful for debugging and performance tuning.
4670
4671	sched_thermal_decay_shift=
4672			[KNL, SMP] Set a decay shift for scheduler thermal
4673			pressure signal. Thermal pressure signal follows the
4674			default decay period of other scheduler pelt
4675			signals(usually 32 ms but configurable). Setting
4676			sched_thermal_decay_shift will left shift the decay
4677			period for the thermal pressure signal by the shift
4678			value.
4679			i.e. with the default pelt decay period of 32 ms
4680			sched_thermal_decay_shift   thermal pressure decay pr
4681				1			64 ms
4682				2			128 ms
4683			and so on.
4684			Format: integer between 0 and 10
4685			Default is 0.
4686
4687	scftorture.holdoff= [KNL]
4688			Number of seconds to hold off before starting
4689			test.  Defaults to zero for module insertion and
4690			to 10 seconds for built-in smp_call_function()
4691			tests.
4692
4693	scftorture.longwait= [KNL]
4694			Request ridiculously long waits randomly selected
4695			up to the chosen limit in seconds.  Zero (the
4696			default) disables this feature.  Please note
4697			that requesting even small non-zero numbers of
4698			seconds can result in RCU CPU stall warnings,
4699			softlockup complaints, and so on.
4700
4701	scftorture.nthreads= [KNL]
4702			Number of kthreads to spawn to invoke the
4703			smp_call_function() family of functions.
4704			The default of -1 specifies a number of kthreads
4705			equal to the number of CPUs.
4706
4707	scftorture.onoff_holdoff= [KNL]
4708			Number seconds to wait after the start of the
4709			test before initiating CPU-hotplug operations.
4710
4711	scftorture.onoff_interval= [KNL]
4712			Number seconds to wait between successive
4713			CPU-hotplug operations.  Specifying zero (which
4714			is the default) disables CPU-hotplug operations.
4715
4716	scftorture.shutdown_secs= [KNL]
4717			The number of seconds following the start of the
4718			test after which to shut down the system.  The
4719			default of zero avoids shutting down the system.
4720			Non-zero values are useful for automated tests.
4721
4722	scftorture.stat_interval= [KNL]
4723			The number of seconds between outputting the
4724			current test statistics to the console.  A value
4725			of zero disables statistics output.
4726
4727	scftorture.stutter_cpus= [KNL]
4728			The number of jiffies to wait between each change
4729			to the set of CPUs under test.
4730
4731	scftorture.use_cpus_read_lock= [KNL]
4732			Use use_cpus_read_lock() instead of the default
4733			preempt_disable() to disable CPU hotplug
4734			while invoking one of the smp_call_function*()
4735			functions.
4736
4737	scftorture.verbose= [KNL]
4738			Enable additional printk() statements.
4739
4740	scftorture.weight_single= [KNL]
4741			The probability weighting to use for the
4742			smp_call_function_single() function with a zero
4743			"wait" parameter.  A value of -1 selects the
4744			default if all other weights are -1.  However,
4745			if at least one weight has some other value, a
4746			value of -1 will instead select a weight of zero.
4747
4748	scftorture.weight_single_wait= [KNL]
4749			The probability weighting to use for the
4750			smp_call_function_single() function with a
4751			non-zero "wait" parameter.  See weight_single.
4752
4753	scftorture.weight_many= [KNL]
4754			The probability weighting to use for the
4755			smp_call_function_many() function with a zero
4756			"wait" parameter.  See weight_single.
4757			Note well that setting a high probability for
4758			this weighting can place serious IPI load
4759			on the system.
4760
4761	scftorture.weight_many_wait= [KNL]
4762			The probability weighting to use for the
4763			smp_call_function_many() function with a
4764			non-zero "wait" parameter.  See weight_single
4765			and weight_many.
4766
4767	scftorture.weight_all= [KNL]
4768			The probability weighting to use for the
4769			smp_call_function_all() function with a zero
4770			"wait" parameter.  See weight_single and
4771			weight_many.
4772
4773	scftorture.weight_all_wait= [KNL]
4774			The probability weighting to use for the
4775			smp_call_function_all() function with a
4776			non-zero "wait" parameter.  See weight_single
4777			and weight_many.
4778
4779	skew_tick=	[KNL] Offset the periodic timer tick per cpu to mitigate
4780			xtime_lock contention on larger systems, and/or RCU lock
4781			contention on all systems with CONFIG_MAXSMP set.
4782			Format: { "0" | "1" }
4783			0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
4784			1 -- enable.
4785			Note: increases power consumption, thus should only be
4786			enabled if running jitter sensitive (HPC/RT) workloads.
4787
4788	security=	[SECURITY] Choose a legacy "major" security module to
4789			enable at boot. This has been deprecated by the
4790			"lsm=" parameter.
4791
4792	selinux=	[SELINUX] Disable or enable SELinux at boot time.
4793			Format: { "0" | "1" }
4794			See security/selinux/Kconfig help text.
4795			0 -- disable.
4796			1 -- enable.
4797			Default value is 1.
4798
4799	apparmor=	[APPARMOR] Disable or enable AppArmor at boot time
4800			Format: { "0" | "1" }
4801			See security/apparmor/Kconfig help text
4802			0 -- disable.
4803			1 -- enable.
4804			Default value is set via kernel config option.
4805
4806	serialnumber	[BUGS=X86-32]
4807
4808	shapers=	[NET]
4809			Maximal number of shapers.
4810
4811	simeth=		[IA-64]
4812	simscsi=
4813
4814	slram=		[HW,MTD]
4815
4816	slab_nomerge	[MM]
4817			Disable merging of slabs with similar size. May be
4818			necessary if there is some reason to distinguish
4819			allocs to different slabs, especially in hardened
4820			environments where the risk of heap overflows and
4821			layout control by attackers can usually be
4822			frustrated by disabling merging. This will reduce
4823			most of the exposure of a heap attack to a single
4824			cache (risks via metadata attacks are mostly
4825			unchanged). Debug options disable merging on their
4826			own.
4827			For more information see Documentation/vm/slub.rst.
4828
4829	slab_max_order=	[MM, SLAB]
4830			Determines the maximum allowed order for slabs.
4831			A high setting may cause OOMs due to memory
4832			fragmentation.  Defaults to 1 for systems with
4833			more than 32MB of RAM, 0 otherwise.
4834
4835	slub_debug[=options[,slabs][;[options[,slabs]]...]	[MM, SLUB]
4836			Enabling slub_debug allows one to determine the
4837			culprit if slab objects become corrupted. Enabling
4838			slub_debug can create guard zones around objects and
4839			may poison objects when not in use. Also tracks the
4840			last alloc / free. For more information see
4841			Documentation/vm/slub.rst.
4842
4843	slub_memcg_sysfs=	[MM, SLUB]
4844			Determines whether to enable sysfs directories for
4845			memory cgroup sub-caches. 1 to enable, 0 to disable.
4846			The default is determined by CONFIG_SLUB_MEMCG_SYSFS_ON.
4847			Enabling this can lead to a very high number of	debug
4848			directories and files being created under
4849			/sys/kernel/slub.
4850
4851	slub_max_order= [MM, SLUB]
4852			Determines the maximum allowed order for slabs.
4853			A high setting may cause OOMs due to memory
4854			fragmentation. For more information see
4855			Documentation/vm/slub.rst.
4856
4857	slub_min_objects=	[MM, SLUB]
4858			The minimum number of objects per slab. SLUB will
4859			increase the slab order up to slub_max_order to
4860			generate a sufficiently large slab able to contain
4861			the number of objects indicated. The higher the number
4862			of objects the smaller the overhead of tracking slabs
4863			and the less frequently locks need to be acquired.
4864			For more information see Documentation/vm/slub.rst.
4865
4866	slub_min_order=	[MM, SLUB]
4867			Determines the minimum page order for slabs. Must be
4868			lower than slub_max_order.
4869			For more information see Documentation/vm/slub.rst.
4870
4871	slub_nomerge	[MM, SLUB]
4872			Same with slab_nomerge. This is supported for legacy.
4873			See slab_nomerge for more information.
4874
4875	smart2=		[HW]
4876			Format: <io1>[,<io2>[,...,<io8>]]
4877
4878	smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
4879	smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
4880	smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
4881	smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
4882	smsc-ircc2.ircc_irq=	[HW] IRQ line
4883	smsc-ircc2.ircc_dma=	[HW] DMA channel
4884	smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
4885				0: Toshiba Satellite 1800 (GP data pin select)
4886				1: Fast pin select (default)
4887				2: ATC IRMode
4888
4889	smt		[KNL,S390] Set the maximum number of threads (logical
4890			CPUs) to use per physical CPU on systems capable of
4891			symmetric multithreading (SMT). Will be capped to the
4892			actual hardware limit.
4893			Format: <integer>
4894			Default: -1 (no limit)
4895
4896	softlockup_panic=
4897			[KNL] Should the soft-lockup detector generate panics.
4898			Format: 0 | 1
4899
4900			A value of 1 instructs the soft-lockup detector
4901			to panic the machine when a soft-lockup occurs. It is
4902			also controlled by the kernel.softlockup_panic sysctl
4903			and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the
4904			respective build-time switch to that functionality.
4905
4906	softlockup_all_cpu_backtrace=
4907			[KNL] Should the soft-lockup detector generate
4908			backtraces on all cpus.
4909			Format: 0 | 1
4910
4911	sonypi.*=	[HW] Sony Programmable I/O Control Device driver
4912			See Documentation/admin-guide/laptops/sonypi.rst
4913
4914	spectre_v2=	[X86] Control mitigation of Spectre variant 2
4915			(indirect branch speculation) vulnerability.
4916			The default operation protects the kernel from
4917			user space attacks.
4918
4919			on   - unconditionally enable, implies
4920			       spectre_v2_user=on
4921			off  - unconditionally disable, implies
4922			       spectre_v2_user=off
4923			auto - kernel detects whether your CPU model is
4924			       vulnerable
4925
4926			Selecting 'on' will, and 'auto' may, choose a
4927			mitigation method at run time according to the
4928			CPU, the available microcode, the setting of the
4929			CONFIG_RETPOLINE configuration option, and the
4930			compiler with which the kernel was built.
4931
4932			Selecting 'on' will also enable the mitigation
4933			against user space to user space task attacks.
4934
4935			Selecting 'off' will disable both the kernel and
4936			the user space protections.
4937
4938			Specific mitigations can also be selected manually:
4939
4940			retpoline	  - replace indirect branches
4941			retpoline,generic - google's original retpoline
4942			retpoline,amd     - AMD-specific minimal thunk
4943
4944			Not specifying this option is equivalent to
4945			spectre_v2=auto.
4946
4947	spectre_v2_user=
4948			[X86] Control mitigation of Spectre variant 2
4949		        (indirect branch speculation) vulnerability between
4950		        user space tasks
4951
4952			on	- Unconditionally enable mitigations. Is
4953				  enforced by spectre_v2=on
4954
4955			off     - Unconditionally disable mitigations. Is
4956				  enforced by spectre_v2=off
4957
4958			prctl   - Indirect branch speculation is enabled,
4959				  but mitigation can be enabled via prctl
4960				  per thread.  The mitigation control state
4961				  is inherited on fork.
4962
4963			prctl,ibpb
4964				- Like "prctl" above, but only STIBP is
4965				  controlled per thread. IBPB is issued
4966				  always when switching between different user
4967				  space processes.
4968
4969			seccomp
4970				- Same as "prctl" above, but all seccomp
4971				  threads will enable the mitigation unless
4972				  they explicitly opt out.
4973
4974			seccomp,ibpb
4975				- Like "seccomp" above, but only STIBP is
4976				  controlled per thread. IBPB is issued
4977				  always when switching between different
4978				  user space processes.
4979
4980			auto    - Kernel selects the mitigation depending on
4981				  the available CPU features and vulnerability.
4982
4983			Default mitigation:
4984			If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl"
4985
4986			Not specifying this option is equivalent to
4987			spectre_v2_user=auto.
4988
4989	spec_store_bypass_disable=
4990			[HW] Control Speculative Store Bypass (SSB) Disable mitigation
4991			(Speculative Store Bypass vulnerability)
4992
4993			Certain CPUs are vulnerable to an exploit against a
4994			a common industry wide performance optimization known
4995			as "Speculative Store Bypass" in which recent stores
4996			to the same memory location may not be observed by
4997			later loads during speculative execution. The idea
4998			is that such stores are unlikely and that they can
4999			be detected prior to instruction retirement at the
5000			end of a particular speculation execution window.
5001
5002			In vulnerable processors, the speculatively forwarded
5003			store can be used in a cache side channel attack, for
5004			example to read memory to which the attacker does not
5005			directly have access (e.g. inside sandboxed code).
5006
5007			This parameter controls whether the Speculative Store
5008			Bypass optimization is used.
5009
5010			On x86 the options are:
5011
5012			on      - Unconditionally disable Speculative Store Bypass
5013			off     - Unconditionally enable Speculative Store Bypass
5014			auto    - Kernel detects whether the CPU model contains an
5015				  implementation of Speculative Store Bypass and
5016				  picks the most appropriate mitigation. If the
5017				  CPU is not vulnerable, "off" is selected. If the
5018				  CPU is vulnerable the default mitigation is
5019				  architecture and Kconfig dependent. See below.
5020			prctl   - Control Speculative Store Bypass per thread
5021				  via prctl. Speculative Store Bypass is enabled
5022				  for a process by default. The state of the control
5023				  is inherited on fork.
5024			seccomp - Same as "prctl" above, but all seccomp threads
5025				  will disable SSB unless they explicitly opt out.
5026
5027			Default mitigations:
5028			X86:	If CONFIG_SECCOMP=y "seccomp", otherwise "prctl"
5029
5030			On powerpc the options are:
5031
5032			on,auto - On Power8 and Power9 insert a store-forwarding
5033				  barrier on kernel entry and exit. On Power7
5034				  perform a software flush on kernel entry and
5035				  exit.
5036			off	- No action.
5037
5038			Not specifying this option is equivalent to
5039			spec_store_bypass_disable=auto.
5040
5041	spia_io_base=	[HW,MTD]
5042	spia_fio_base=
5043	spia_pedr=
5044	spia_peddr=
5045
5046	split_lock_detect=
5047			[X86] Enable split lock detection
5048
5049			When enabled (and if hardware support is present), atomic
5050			instructions that access data across cache line
5051			boundaries will result in an alignment check exception.
5052
5053			off	- not enabled
5054
5055			warn	- the kernel will emit rate limited warnings
5056				  about applications triggering the #AC
5057				  exception. This mode is the default on CPUs
5058				  that supports split lock detection.
5059
5060			fatal	- the kernel will send SIGBUS to applications
5061				  that trigger the #AC exception.
5062
5063			If an #AC exception is hit in the kernel or in
5064			firmware (i.e. not while executing in user mode)
5065			the kernel will oops in either "warn" or "fatal"
5066			mode.
5067
5068	srbds=		[X86,INTEL]
5069			Control the Special Register Buffer Data Sampling
5070			(SRBDS) mitigation.
5071
5072			Certain CPUs are vulnerable to an MDS-like
5073			exploit which can leak bits from the random
5074			number generator.
5075
5076			By default, this issue is mitigated by
5077			microcode.  However, the microcode fix can cause
5078			the RDRAND and RDSEED instructions to become
5079			much slower.  Among other effects, this will
5080			result in reduced throughput from /dev/urandom.
5081
5082			The microcode mitigation can be disabled with
5083			the following option:
5084
5085			off:    Disable mitigation and remove
5086				performance impact to RDRAND and RDSEED
5087
5088	srcutree.counter_wrap_check [KNL]
5089			Specifies how frequently to check for
5090			grace-period sequence counter wrap for the
5091			srcu_data structure's ->srcu_gp_seq_needed field.
5092			The greater the number of bits set in this kernel
5093			parameter, the less frequently counter wrap will
5094			be checked for.  Note that the bottom two bits
5095			are ignored.
5096
5097	srcutree.exp_holdoff [KNL]
5098			Specifies how many nanoseconds must elapse
5099			since the end of the last SRCU grace period for
5100			a given srcu_struct until the next normal SRCU
5101			grace period will be considered for automatic
5102			expediting.  Set to zero to disable automatic
5103			expediting.
5104
5105	ssbd=		[ARM64,HW]
5106			Speculative Store Bypass Disable control
5107
5108			On CPUs that are vulnerable to the Speculative
5109			Store Bypass vulnerability and offer a
5110			firmware based mitigation, this parameter
5111			indicates how the mitigation should be used:
5112
5113			force-on:  Unconditionally enable mitigation for
5114				   for both kernel and userspace
5115			force-off: Unconditionally disable mitigation for
5116				   for both kernel and userspace
5117			kernel:    Always enable mitigation in the
5118				   kernel, and offer a prctl interface
5119				   to allow userspace to register its
5120				   interest in being mitigated too.
5121
5122	stack_guard_gap=	[MM]
5123			override the default stack gap protection. The value
5124			is in page units and it defines how many pages prior
5125			to (for stacks growing down) resp. after (for stacks
5126			growing up) the main stack are reserved for no other
5127			mapping. Default value is 256 pages.
5128
5129	stacktrace	[FTRACE]
5130			Enabled the stack tracer on boot up.
5131
5132	stacktrace_filter=[function-list]
5133			[FTRACE] Limit the functions that the stack tracer
5134			will trace at boot up. function-list is a comma separated
5135			list of functions. This list can be changed at run
5136			time by the stack_trace_filter file in the debugfs
5137			tracing directory. Note, this enables stack tracing
5138			and the stacktrace above is not needed.
5139
5140	sti=		[PARISC,HW]
5141			Format: <num>
5142			Set the STI (builtin display/keyboard on the HP-PARISC
5143			machines) console (graphic card) which should be used
5144			as the initial boot-console.
5145			See also comment in drivers/video/console/sticore.c.
5146
5147	sti_font=	[HW]
5148			See comment in drivers/video/console/sticore.c.
5149
5150	stifb=		[HW]
5151			Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
5152
5153	sunrpc.min_resvport=
5154	sunrpc.max_resvport=
5155			[NFS,SUNRPC]
5156			SunRPC servers often require that client requests
5157			originate from a privileged port (i.e. a port in the
5158			range 0 < portnr < 1024).
5159			An administrator who wishes to reserve some of these
5160			ports for other uses may adjust the range that the
5161			kernel's sunrpc client considers to be privileged
5162			using these two parameters to set the minimum and
5163			maximum port values.
5164
5165	sunrpc.svc_rpc_per_connection_limit=
5166			[NFS,SUNRPC]
5167			Limit the number of requests that the server will
5168			process in parallel from a single connection.
5169			The default value is 0 (no limit).
5170
5171	sunrpc.pool_mode=
5172			[NFS]
5173			Control how the NFS server code allocates CPUs to
5174			service thread pools.  Depending on how many NICs
5175			you have and where their interrupts are bound, this
5176			option will affect which CPUs will do NFS serving.
5177			Note: this parameter cannot be changed while the
5178			NFS server is running.
5179
5180			auto	    the server chooses an appropriate mode
5181				    automatically using heuristics
5182			global	    a single global pool contains all CPUs
5183			percpu	    one pool for each CPU
5184			pernode	    one pool for each NUMA node (equivalent
5185				    to global on non-NUMA machines)
5186
5187	sunrpc.tcp_slot_table_entries=
5188	sunrpc.udp_slot_table_entries=
5189			[NFS,SUNRPC]
5190			Sets the upper limit on the number of simultaneous
5191			RPC calls that can be sent from the client to a
5192			server. Increasing these values may allow you to
5193			improve throughput, but will also increase the
5194			amount of memory reserved for use by the client.
5195
5196	suspend.pm_test_delay=
5197			[SUSPEND]
5198			Sets the number of seconds to remain in a suspend test
5199			mode before resuming the system (see
5200			/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
5201			is set. Default value is 5.
5202
5203	svm=		[PPC]
5204			Format: { on | off | y | n | 1 | 0 }
5205			This parameter controls use of the Protected
5206			Execution Facility on pSeries.
5207
5208	swapaccount=[0|1]
5209			[KNL] Enable accounting of swap in memory resource
5210			controller if no parameter or 1 is given or disable
5211			it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)
5212
5213	swiotlb=	[ARM,IA-64,PPC,MIPS,X86]
5214			Format: { <int> | force | noforce }
5215			<int> -- Number of I/O TLB slabs
5216			force -- force using of bounce buffers even if they
5217			         wouldn't be automatically used by the kernel
5218			noforce -- Never use bounce buffers (for debugging)
5219
5220	switches=	[HW,M68k]
5221
5222	sysctl.*=	[KNL]
5223			Set a sysctl parameter, right before loading the init
5224			process, as if the value was written to the respective
5225			/proc/sys/... file. Both '.' and '/' are recognized as
5226			separators. Unrecognized parameters and invalid values
5227			are reported in the kernel log. Sysctls registered
5228			later by a loaded module cannot be set this way.
5229			Example: sysctl.vm.swappiness=40
5230
5231	sysfs.deprecated=0|1 [KNL]
5232			Enable/disable old style sysfs layout for old udev
5233			on older distributions. When this option is enabled
5234			very new udev will not work anymore. When this option
5235			is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
5236			in older udev will not work anymore.
5237			Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
5238			the kernel configuration.
5239
5240	sysrq_always_enabled
5241			[KNL]
5242			Ignore sysrq setting - this boot parameter will
5243			neutralize any effect of /proc/sys/kernel/sysrq.
5244			Useful for debugging.
5245
5246	tcpmhash_entries= [KNL,NET]
5247			Set the number of tcp_metrics_hash slots.
5248			Default value is 8192 or 16384 depending on total
5249			ram pages. This is used to specify the TCP metrics
5250			cache size. See Documentation/networking/ip-sysctl.rst
5251			"tcp_no_metrics_save" section for more details.
5252
5253	tdfx=		[HW,DRM]
5254
5255	test_suspend=	[SUSPEND][,N]
5256			Specify "mem" (for Suspend-to-RAM) or "standby" (for
5257			standby suspend) or "freeze" (for suspend type freeze)
5258			as the system sleep state during system startup with
5259			the optional capability to repeat N number of times.
5260			The system is woken from this state using a
5261			wakeup-capable RTC alarm.
5262
5263	thash_entries=	[KNL,NET]
5264			Set number of hash buckets for TCP connection
5265
5266	thermal.act=	[HW,ACPI]
5267			-1: disable all active trip points in all thermal zones
5268			<degrees C>: override all lowest active trip points
5269
5270	thermal.crt=	[HW,ACPI]
5271			-1: disable all critical trip points in all thermal zones
5272			<degrees C>: override all critical trip points
5273
5274	thermal.nocrt=	[HW,ACPI]
5275			Set to disable actions on ACPI thermal zone
5276			critical and hot trip points.
5277
5278	thermal.off=	[HW,ACPI]
5279			1: disable ACPI thermal control
5280
5281	thermal.psv=	[HW,ACPI]
5282			-1: disable all passive trip points
5283			<degrees C>: override all passive trip points to this
5284			value
5285
5286	thermal.tzp=	[HW,ACPI]
5287			Specify global default ACPI thermal zone polling rate
5288			<deci-seconds>: poll all this frequency
5289			0: no polling (default)
5290
5291	threadirqs	[KNL]
5292			Force threading of all interrupt handlers except those
5293			marked explicitly IRQF_NO_THREAD.
5294
5295	topology=	[S390]
5296			Format: {off | on}
5297			Specify if the kernel should make use of the cpu
5298			topology information if the hardware supports this.
5299			The scheduler will make use of this information and
5300			e.g. base its process migration decisions on it.
5301			Default is on.
5302
5303	topology_updates= [KNL, PPC, NUMA]
5304			Format: {off}
5305			Specify if the kernel should ignore (off)
5306			topology updates sent by the hypervisor to this
5307			LPAR.
5308
5309	torture.disable_onoff_at_boot= [KNL]
5310			Prevent the CPU-hotplug component of torturing
5311			until after init has spawned.
5312
5313	torture.ftrace_dump_at_shutdown= [KNL]
5314			Dump the ftrace buffer at torture-test shutdown,
5315			even if there were no errors.  This can be a
5316			very costly operation when many torture tests
5317			are running concurrently, especially on systems
5318			with rotating-rust storage.
5319
5320	tp720=		[HW,PS2]
5321
5322	tpm_suspend_pcr=[HW,TPM]
5323			Format: integer pcr id
5324			Specify that at suspend time, the tpm driver
5325			should extend the specified pcr with zeros,
5326			as a workaround for some chips which fail to
5327			flush the last written pcr on TPM_SaveState.
5328			This will guarantee that all the other pcrs
5329			are saved.
5330
5331	trace_buf_size=nn[KMG]
5332			[FTRACE] will set tracing buffer size on each cpu.
5333
5334	trace_event=[event-list]
5335			[FTRACE] Set and start specified trace events in order
5336			to facilitate early boot debugging. The event-list is a
5337			comma separated list of trace events to enable. See
5338			also Documentation/trace/events.rst
5339
5340	trace_options=[option-list]
5341			[FTRACE] Enable or disable tracer options at boot.
5342			The option-list is a comma delimited list of options
5343			that can be enabled or disabled just as if you were
5344			to echo the option name into
5345
5346			    /sys/kernel/debug/tracing/trace_options
5347
5348			For example, to enable stacktrace option (to dump the
5349			stack trace of each event), add to the command line:
5350
5351			      trace_options=stacktrace
5352
5353			See also Documentation/trace/ftrace.rst "trace options"
5354			section.
5355
5356	tp_printk[FTRACE]
5357			Have the tracepoints sent to printk as well as the
5358			tracing ring buffer. This is useful for early boot up
5359			where the system hangs or reboots and does not give the
5360			option for reading the tracing buffer or performing a
5361			ftrace_dump_on_oops.
5362
5363			To turn off having tracepoints sent to printk,
5364			 echo 0 > /proc/sys/kernel/tracepoint_printk
5365			Note, echoing 1 into this file without the
5366			tracepoint_printk kernel cmdline option has no effect.
5367
5368			** CAUTION **
5369
5370			Having tracepoints sent to printk() and activating high
5371			frequency tracepoints such as irq or sched, can cause
5372			the system to live lock.
5373
5374	traceoff_on_warning
5375			[FTRACE] enable this option to disable tracing when a
5376			warning is hit. This turns off "tracing_on". Tracing can
5377			be enabled again by echoing '1' into the "tracing_on"
5378			file located in /sys/kernel/debug/tracing/
5379
5380			This option is useful, as it disables the trace before
5381			the WARNING dump is called, which prevents the trace to
5382			be filled with content caused by the warning output.
5383
5384			This option can also be set at run time via the sysctl
5385			option:  kernel/traceoff_on_warning
5386
5387	transparent_hugepage=
5388			[KNL]
5389			Format: [always|madvise|never]
5390			Can be used to control the default behavior of the system
5391			with respect to transparent hugepages.
5392			See Documentation/admin-guide/mm/transhuge.rst
5393			for more details.
5394
5395	tsc=		Disable clocksource stability checks for TSC.
5396			Format: <string>
5397			[x86] reliable: mark tsc clocksource as reliable, this
5398			disables clocksource verification at runtime, as well
5399			as the stability checks done at bootup.	Used to enable
5400			high-resolution timer mode on older hardware, and in
5401			virtualized environment.
5402			[x86] noirqtime: Do not use TSC to do irq accounting.
5403			Used to run time disable IRQ_TIME_ACCOUNTING on any
5404			platforms where RDTSC is slow and this accounting
5405			can add overhead.
5406			[x86] unstable: mark the TSC clocksource as unstable, this
5407			marks the TSC unconditionally unstable at bootup and
5408			avoids any further wobbles once the TSC watchdog notices.
5409			[x86] nowatchdog: disable clocksource watchdog. Used
5410			in situations with strict latency requirements (where
5411			interruptions from clocksource watchdog are not
5412			acceptable).
5413
5414	tsc_early_khz=  [X86] Skip early TSC calibration and use the given
5415			value instead. Useful when the early TSC frequency discovery
5416			procedure is not reliable, such as on overclocked systems
5417			with CPUID.16h support and partial CPUID.15h support.
5418			Format: <unsigned int>
5419
5420	tsx=		[X86] Control Transactional Synchronization
5421			Extensions (TSX) feature in Intel processors that
5422			support TSX control.
5423
5424			This parameter controls the TSX feature. The options are:
5425
5426			on	- Enable TSX on the system. Although there are
5427				mitigations for all known security vulnerabilities,
5428				TSX has been known to be an accelerator for
5429				several previous speculation-related CVEs, and
5430				so there may be unknown	security risks associated
5431				with leaving it enabled.
5432
5433			off	- Disable TSX on the system. (Note that this
5434				option takes effect only on newer CPUs which are
5435				not vulnerable to MDS, i.e., have
5436				MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1 and which get
5437				the new IA32_TSX_CTRL MSR through a microcode
5438				update. This new MSR allows for the reliable
5439				deactivation of the TSX functionality.)
5440
5441			auto	- Disable TSX if X86_BUG_TAA is present,
5442				  otherwise enable TSX on the system.
5443
5444			Not specifying this option is equivalent to tsx=off.
5445
5446			See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5447			for more details.
5448
5449	tsx_async_abort= [X86,INTEL] Control mitigation for the TSX Async
5450			Abort (TAA) vulnerability.
5451
5452			Similar to Micro-architectural Data Sampling (MDS)
5453			certain CPUs that support Transactional
5454			Synchronization Extensions (TSX) are vulnerable to an
5455			exploit against CPU internal buffers which can forward
5456			information to a disclosure gadget under certain
5457			conditions.
5458
5459			In vulnerable processors, the speculatively forwarded
5460			data can be used in a cache side channel attack, to
5461			access data to which the attacker does not have direct
5462			access.
5463
5464			This parameter controls the TAA mitigation.  The
5465			options are:
5466
5467			full       - Enable TAA mitigation on vulnerable CPUs
5468				     if TSX is enabled.
5469
5470			full,nosmt - Enable TAA mitigation and disable SMT on
5471				     vulnerable CPUs. If TSX is disabled, SMT
5472				     is not disabled because CPU is not
5473				     vulnerable to cross-thread TAA attacks.
5474			off        - Unconditionally disable TAA mitigation
5475
5476			On MDS-affected machines, tsx_async_abort=off can be
5477			prevented by an active MDS mitigation as both vulnerabilities
5478			are mitigated with the same mechanism so in order to disable
5479			this mitigation, you need to specify mds=off too.
5480
5481			Not specifying this option is equivalent to
5482			tsx_async_abort=full.  On CPUs which are MDS affected
5483			and deploy MDS mitigation, TAA mitigation is not
5484			required and doesn't provide any additional
5485			mitigation.
5486
5487			For details see:
5488			Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5489
5490	turbografx.map[2|3]=	[HW,JOY]
5491			TurboGraFX parallel port interface
5492			Format:
5493			<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
5494			See also Documentation/input/devices/joystick-parport.rst
5495
5496	udbg-immortal	[PPC] When debugging early kernel crashes that
5497			happen after console_init() and before a proper
5498			console driver takes over, this boot options might
5499			help "seeing" what's going on.
5500
5501	uhash_entries=	[KNL,NET]
5502			Set number of hash buckets for UDP/UDP-Lite connections
5503
5504	uhci-hcd.ignore_oc=
5505			[USB] Ignore overcurrent events (default N).
5506			Some badly-designed motherboards generate lots of
5507			bogus events, for ports that aren't wired to
5508			anything.  Set this parameter to avoid log spamming.
5509			Note that genuine overcurrent events won't be
5510			reported either.
5511
5512	unknown_nmi_panic
5513			[X86] Cause panic on unknown NMI.
5514
5515	usbcore.authorized_default=
5516			[USB] Default USB device authorization:
5517			(default -1 = authorized except for wireless USB,
5518			0 = not authorized, 1 = authorized, 2 = authorized
5519			if device connected to internal port)
5520
5521	usbcore.autosuspend=
5522			[USB] The autosuspend time delay (in seconds) used
5523			for newly-detected USB devices (default 2).  This
5524			is the time required before an idle device will be
5525			autosuspended.  Devices for which the delay is set
5526			to a negative value won't be autosuspended at all.
5527
5528	usbcore.usbfs_snoop=
5529			[USB] Set to log all usbfs traffic (default 0 = off).
5530
5531	usbcore.usbfs_snoop_max=
5532			[USB] Maximum number of bytes to snoop in each URB
5533			(default = 65536).
5534
5535	usbcore.blinkenlights=
5536			[USB] Set to cycle leds on hubs (default 0 = off).
5537
5538	usbcore.old_scheme_first=
5539			[USB] Start with the old device initialization
5540			scheme (default 0 = off).
5541
5542	usbcore.usbfs_memory_mb=
5543			[USB] Memory limit (in MB) for buffers allocated by
5544			usbfs (default = 16, 0 = max = 2047).
5545
5546	usbcore.use_both_schemes=
5547			[USB] Try the other device initialization scheme
5548			if the first one fails (default 1 = enabled).
5549
5550	usbcore.initial_descriptor_timeout=
5551			[USB] Specifies timeout for the initial 64-byte
5552			USB_REQ_GET_DESCRIPTOR request in milliseconds
5553			(default 5000 = 5.0 seconds).
5554
5555	usbcore.nousb	[USB] Disable the USB subsystem
5556
5557	usbcore.quirks=
5558			[USB] A list of quirk entries to augment the built-in
5559			usb core quirk list. List entries are separated by
5560			commas. Each entry has the form
5561			VendorID:ProductID:Flags. The IDs are 4-digit hex
5562			numbers and Flags is a set of letters. Each letter
5563			will change the built-in quirk; setting it if it is
5564			clear and clearing it if it is set. The letters have
5565			the following meanings:
5566				a = USB_QUIRK_STRING_FETCH_255 (string
5567					descriptors must not be fetched using
5568					a 255-byte read);
5569				b = USB_QUIRK_RESET_RESUME (device can't resume
5570					correctly so reset it instead);
5571				c = USB_QUIRK_NO_SET_INTF (device can't handle
5572					Set-Interface requests);
5573				d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't
5574					handle its Configuration or Interface
5575					strings);
5576				e = USB_QUIRK_RESET (device can't be reset
5577					(e.g morph devices), don't use reset);
5578				f = USB_QUIRK_HONOR_BNUMINTERFACES (device has
5579					more interface descriptions than the
5580					bNumInterfaces count, and can't handle
5581					talking to these interfaces);
5582				g = USB_QUIRK_DELAY_INIT (device needs a pause
5583					during initialization, after we read
5584					the device descriptor);
5585				h = USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL (For
5586					high speed and super speed interrupt
5587					endpoints, the USB 2.0 and USB 3.0 spec
5588					require the interval in microframes (1
5589					microframe = 125 microseconds) to be
5590					calculated as interval = 2 ^
5591					(bInterval-1).
5592					Devices with this quirk report their
5593					bInterval as the result of this
5594					calculation instead of the exponent
5595					variable used in the calculation);
5596				i = USB_QUIRK_DEVICE_QUALIFIER (device can't
5597					handle device_qualifier descriptor
5598					requests);
5599				j = USB_QUIRK_IGNORE_REMOTE_WAKEUP (device
5600					generates spurious wakeup, ignore
5601					remote wakeup capability);
5602				k = USB_QUIRK_NO_LPM (device can't handle Link
5603					Power Management);
5604				l = USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL
5605					(Device reports its bInterval as linear
5606					frames instead of the USB 2.0
5607					calculation);
5608				m = USB_QUIRK_DISCONNECT_SUSPEND (Device needs
5609					to be disconnected before suspend to
5610					prevent spurious wakeup);
5611				n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a
5612					pause after every control message);
5613				o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra
5614					delay after resetting its port);
5615			Example: quirks=0781:5580:bk,0a5c:5834:gij
5616
5617	usbhid.mousepoll=
5618			[USBHID] The interval which mice are to be polled at.
5619
5620	usbhid.jspoll=
5621			[USBHID] The interval which joysticks are to be polled at.
5622
5623	usbhid.kbpoll=
5624			[USBHID] The interval which keyboards are to be polled at.
5625
5626	usb-storage.delay_use=
5627			[UMS] The delay in seconds before a new device is
5628			scanned for Logical Units (default 1).
5629
5630	usb-storage.quirks=
5631			[UMS] A list of quirks entries to supplement or
5632			override the built-in unusual_devs list.  List
5633			entries are separated by commas.  Each entry has
5634			the form VID:PID:Flags where VID and PID are Vendor
5635			and Product ID values (4-digit hex numbers) and
5636			Flags is a set of characters, each corresponding
5637			to a common usb-storage quirk flag as follows:
5638				a = SANE_SENSE (collect more than 18 bytes
5639					of sense data, not on uas);
5640				b = BAD_SENSE (don't collect more than 18
5641					bytes of sense data, not on uas);
5642				c = FIX_CAPACITY (decrease the reported
5643					device capacity by one sector);
5644				d = NO_READ_DISC_INFO (don't use
5645					READ_DISC_INFO command, not on uas);
5646				e = NO_READ_CAPACITY_16 (don't use
5647					READ_CAPACITY_16 command);
5648				f = NO_REPORT_OPCODES (don't use report opcodes
5649					command, uas only);
5650				g = MAX_SECTORS_240 (don't transfer more than
5651					240 sectors at a time, uas only);
5652				h = CAPACITY_HEURISTICS (decrease the
5653					reported device capacity by one
5654					sector if the number is odd);
5655				i = IGNORE_DEVICE (don't bind to this
5656					device);
5657				j = NO_REPORT_LUNS (don't use report luns
5658					command, uas only);
5659				l = NOT_LOCKABLE (don't try to lock and
5660					unlock ejectable media, not on uas);
5661				m = MAX_SECTORS_64 (don't transfer more
5662					than 64 sectors = 32 KB at a time,
5663					not on uas);
5664				n = INITIAL_READ10 (force a retry of the
5665					initial READ(10) command, not on uas);
5666				o = CAPACITY_OK (accept the capacity
5667					reported by the device, not on uas);
5668				p = WRITE_CACHE (the device cache is ON
5669					by default, not on uas);
5670				r = IGNORE_RESIDUE (the device reports
5671					bogus residue values, not on uas);
5672				s = SINGLE_LUN (the device has only one
5673					Logical Unit);
5674				t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
5675					commands, uas only);
5676				u = IGNORE_UAS (don't bind to the uas driver);
5677				w = NO_WP_DETECT (don't test whether the
5678					medium is write-protected).
5679				y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE
5680					even if the device claims no cache,
5681					not on uas)
5682			Example: quirks=0419:aaf5:rl,0421:0433:rc
5683
5684	user_debug=	[KNL,ARM]
5685			Format: <int>
5686			See arch/arm/Kconfig.debug help text.
5687				 1 - undefined instruction events
5688				 2 - system calls
5689				 4 - invalid data aborts
5690				 8 - SIGSEGV faults
5691				16 - SIGBUS faults
5692			Example: user_debug=31
5693
5694	userpte=
5695			[X86] Flags controlling user PTE allocations.
5696
5697				nohigh = do not allocate PTE pages in
5698					HIGHMEM regardless of setting
5699					of CONFIG_HIGHPTE.
5700
5701	vdso=		[X86,SH]
5702			On X86_32, this is an alias for vdso32=.  Otherwise:
5703
5704			vdso=1: enable VDSO (the default)
5705			vdso=0: disable VDSO mapping
5706
5707	vdso32=		[X86] Control the 32-bit vDSO
5708			vdso32=1: enable 32-bit VDSO
5709			vdso32=0 or vdso32=2: disable 32-bit VDSO
5710
5711			See the help text for CONFIG_COMPAT_VDSO for more
5712			details.  If CONFIG_COMPAT_VDSO is set, the default is
5713			vdso32=0; otherwise, the default is vdso32=1.
5714
5715			For compatibility with older kernels, vdso32=2 is an
5716			alias for vdso32=0.
5717
5718			Try vdso32=0 if you encounter an error that says:
5719			dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
5720
5721	vector=		[IA-64,SMP]
5722			vector=percpu: enable percpu vector domain
5723
5724	video=		[FB] Frame buffer configuration
5725			See Documentation/fb/modedb.rst.
5726
5727	video.brightness_switch_enabled= [0,1]
5728			If set to 1, on receiving an ACPI notify event
5729			generated by hotkey, video driver will adjust brightness
5730			level and then send out the event to user space through
5731			the allocated input device; If set to 0, video driver
5732			will only send out the event without touching backlight
5733			brightness level.
5734			default: 1
5735
5736	virtio_mmio.device=
5737			[VMMIO] Memory mapped virtio (platform) device.
5738
5739				<size>@<baseaddr>:<irq>[:<id>]
5740			where:
5741				<size>     := size (can use standard suffixes
5742						like K, M and G)
5743				<baseaddr> := physical base address
5744				<irq>      := interrupt number (as passed to
5745						request_irq())
5746				<id>       := (optional) platform device id
5747			example:
5748				virtio_mmio.device=1K@0x100b0000:48:7
5749
5750			Can be used multiple times for multiple devices.
5751
5752	vga=		[BOOT,X86-32] Select a particular video mode
5753			See Documentation/x86/boot.rst and
5754			Documentation/admin-guide/svga.rst.
5755			Use vga=ask for menu.
5756			This is actually a boot loader parameter; the value is
5757			passed to the kernel using a special protocol.
5758
5759	vm_debug[=options]	[KNL] Available with CONFIG_DEBUG_VM=y.
5760			May slow down system boot speed, especially when
5761			enabled on systems with a large amount of memory.
5762			All options are enabled by default, and this
5763			interface is meant to allow for selectively
5764			enabling or disabling specific virtual memory
5765			debugging features.
5766
5767			Available options are:
5768			  P	Enable page structure init time poisoning
5769			  -	Disable all of the above options
5770
5771	vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
5772			size of <nn>. This can be used to increase the
5773			minimum size (128MB on x86). It can also be used to
5774			decrease the size and leave more room for directly
5775			mapped kernel RAM.
5776
5777	vmcp_cma=nn[MG]	[KNL,S390]
5778			Sets the memory size reserved for contiguous memory
5779			allocations for the vmcp device driver.
5780
5781	vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
5782			Format: <command>
5783
5784	vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
5785			Format: <command>
5786
5787	vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
5788			Format: <command>
5789
5790	vsyscall=	[X86-64]
5791			Controls the behavior of vsyscalls (i.e. calls to
5792			fixed addresses of 0xffffffffff600x00 from legacy
5793			code).  Most statically-linked binaries and older
5794			versions of glibc use these calls.  Because these
5795			functions are at fixed addresses, they make nice
5796			targets for exploits that can control RIP.
5797
5798			emulate     [default] Vsyscalls turn into traps and are
5799			            emulated reasonably safely.  The vsyscall
5800				    page is readable.
5801
5802			xonly       Vsyscalls turn into traps and are
5803			            emulated reasonably safely.  The vsyscall
5804				    page is not readable.
5805
5806			none        Vsyscalls don't work at all.  This makes
5807			            them quite hard to use for exploits but
5808			            might break your system.
5809
5810	vt.color=	[VT] Default text color.
5811			Format: 0xYX, X = foreground, Y = background.
5812			Default: 0x07 = light gray on black.
5813
5814	vt.cur_default=	[VT] Default cursor shape.
5815			Format: 0xCCBBAA, where AA, BB, and CC are the same as
5816			the parameters of the <Esc>[?A;B;Cc escape sequence;
5817			see VGA-softcursor.txt. Default: 2 = underline.
5818
5819	vt.default_blu=	[VT]
5820			Format: <blue0>,<blue1>,<blue2>,...,<blue15>
5821			Change the default blue palette of the console.
5822			This is a 16-member array composed of values
5823			ranging from 0-255.
5824
5825	vt.default_grn=	[VT]
5826			Format: <green0>,<green1>,<green2>,...,<green15>
5827			Change the default green palette of the console.
5828			This is a 16-member array composed of values
5829			ranging from 0-255.
5830
5831	vt.default_red=	[VT]
5832			Format: <red0>,<red1>,<red2>,...,<red15>
5833			Change the default red palette of the console.
5834			This is a 16-member array composed of values
5835			ranging from 0-255.
5836
5837	vt.default_utf8=
5838			[VT]
5839			Format=<0|1>
5840			Set system-wide default UTF-8 mode for all tty's.
5841			Default is 1, i.e. UTF-8 mode is enabled for all
5842			newly opened terminals.
5843
5844	vt.global_cursor_default=
5845			[VT]
5846			Format=<-1|0|1>
5847			Set system-wide default for whether a cursor
5848			is shown on new VTs. Default is -1,
5849			i.e. cursors will be created by default unless
5850			overridden by individual drivers. 0 will hide
5851			cursors, 1 will display them.
5852
5853	vt.italic=	[VT] Default color for italic text; 0-15.
5854			Default: 2 = green.
5855
5856	vt.underline=	[VT] Default color for underlined text; 0-15.
5857			Default: 3 = cyan.
5858
5859	watchdog timers	[HW,WDT] For information on watchdog timers,
5860			see Documentation/watchdog/watchdog-parameters.rst
5861			or other driver-specific files in the
5862			Documentation/watchdog/ directory.
5863
5864	watchdog_thresh=
5865			[KNL]
5866			Set the hard lockup detector stall duration
5867			threshold in seconds. The soft lockup detector
5868			threshold is set to twice the value. A value of 0
5869			disables both lockup detectors. Default is 10
5870			seconds.
5871
5872	workqueue.watchdog_thresh=
5873			If CONFIG_WQ_WATCHDOG is configured, workqueue can
5874			warn stall conditions and dump internal state to
5875			help debugging.  0 disables workqueue stall
5876			detection; otherwise, it's the stall threshold
5877			duration in seconds.  The default value is 30 and
5878			it can be updated at runtime by writing to the
5879			corresponding sysfs file.
5880
5881	workqueue.disable_numa
5882			By default, all work items queued to unbound
5883			workqueues are affine to the NUMA nodes they're
5884			issued on, which results in better behavior in
5885			general.  If NUMA affinity needs to be disabled for
5886			whatever reason, this option can be used.  Note
5887			that this also can be controlled per-workqueue for
5888			workqueues visible under /sys/bus/workqueue/.
5889
5890	workqueue.power_efficient
5891			Per-cpu workqueues are generally preferred because
5892			they show better performance thanks to cache
5893			locality; unfortunately, per-cpu workqueues tend to
5894			be more power hungry than unbound workqueues.
5895
5896			Enabling this makes the per-cpu workqueues which
5897			were observed to contribute significantly to power
5898			consumption unbound, leading to measurably lower
5899			power usage at the cost of small performance
5900			overhead.
5901
5902			The default value of this parameter is determined by
5903			the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
5904
5905	workqueue.debug_force_rr_cpu
5906			Workqueue used to implicitly guarantee that work
5907			items queued without explicit CPU specified are put
5908			on the local CPU.  This guarantee is no longer true
5909			and while local CPU is still preferred work items
5910			may be put on foreign CPUs.  This debug option
5911			forces round-robin CPU selection to flush out
5912			usages which depend on the now broken guarantee.
5913			When enabled, memory and cache locality will be
5914			impacted.
5915
5916	x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
5917			default x2apic cluster mode on platforms
5918			supporting x2apic.
5919
5920	x86_intel_mid_timer= [X86-32,APBT]
5921			Choose timer option for x86 Intel MID platform.
5922			Two valid options are apbt timer only and lapic timer
5923			plus one apbt timer for broadcast timer.
5924			x86_intel_mid_timer=apbt_only | lapic_and_apbt
5925
5926	xen_512gb_limit		[KNL,X86-64,XEN]
5927			Restricts the kernel running paravirtualized under Xen
5928			to use only up to 512 GB of RAM. The reason to do so is
5929			crash analysis tools and Xen tools for doing domain
5930			save/restore/migration must be enabled to handle larger
5931			domains.
5932
5933	xen_emul_unplug=		[HW,X86,XEN]
5934			Unplug Xen emulated devices
5935			Format: [unplug0,][unplug1]
5936			ide-disks -- unplug primary master IDE devices
5937			aux-ide-disks -- unplug non-primary-master IDE devices
5938			nics -- unplug network devices
5939			all -- unplug all emulated devices (NICs and IDE disks)
5940			unnecessary -- unplugging emulated devices is
5941				unnecessary even if the host did not respond to
5942				the unplug protocol
5943			never -- do not unplug even if version check succeeds
5944
5945	xen_legacy_crash	[X86,XEN]
5946			Crash from Xen panic notifier, without executing late
5947			panic() code such as dumping handler.
5948
5949	xen_nopvspin	[X86,XEN]
5950			Disables the qspinlock slowpath using Xen PV optimizations.
5951			This parameter is obsoleted by "nopvspin" parameter, which
5952			has equivalent effect for XEN platform.
5953
5954	xen_nopv	[X86]
5955			Disables the PV optimizations forcing the HVM guest to
5956			run as generic HVM guest with no PV drivers.
5957			This option is obsoleted by the "nopv" option, which
5958			has equivalent effect for XEN platform.
5959
5960	xen_scrub_pages=	[XEN]
5961			Boolean option to control scrubbing pages before giving them back
5962			to Xen, for use by other domains. Can be also changed at runtime
5963			with /sys/devices/system/xen_memory/xen_memory0/scrub_pages.
5964			Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.
5965
5966	xen_timer_slop=	[X86-64,XEN]
5967			Set the timer slop (in nanoseconds) for the virtual Xen
5968			timers (default is 100000). This adjusts the minimum
5969			delta of virtualized Xen timers, where lower values
5970			improve timer resolution at the expense of processing
5971			more timer interrupts.
5972
5973	xen.event_eoi_delay=	[XEN]
5974			How long to delay EOI handling in case of event
5975			storms (jiffies). Default is 10.
5976
5977	xen.event_loop_timeout=	[XEN]
5978			After which time (jiffies) the event handling loop
5979			should start to delay EOI handling. Default is 2.
5980
5981	xen.fifo_events=	[XEN]
5982			Boolean parameter to disable using fifo event handling
5983			even if available. Normally fifo event handling is
5984			preferred over the 2-level event handling, as it is
5985			fairer and the number of possible event channels is
5986			much higher. Default is on (use fifo events).
5987
5988	nopv=		[X86,XEN,KVM,HYPER_V,VMWARE]
5989			Disables the PV optimizations forcing the guest to run
5990			as generic guest with no PV drivers. Currently support
5991			XEN HVM, KVM, HYPER_V and VMWARE guest.
5992
5993	nopvspin	[X86,XEN,KVM]
5994			Disables the qspinlock slow path using PV optimizations
5995			which allow the hypervisor to 'idle' the guest on lock
5996			contention.
5997
5998	xirc2ps_cs=	[NET,PCMCIA]
5999			Format:
6000			<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
6001
6002	xive=		[PPC]
6003			By default on POWER9 and above, the kernel will
6004			natively use the XIVE interrupt controller. This option
6005			allows the fallback firmware mode to be used:
6006
6007			off       Fallback to firmware control of XIVE interrupt
6008				  controller on both pseries and powernv
6009				  platforms. Only useful on POWER9 and above.
6010
6011	xhci-hcd.quirks		[USB,KNL]
6012			A hex value specifying bitmask with supplemental xhci
6013			host controller quirks. Meaning of each bit can be
6014			consulted in header drivers/usb/host/xhci.h.
6015
6016	xmon		[PPC]
6017			Format: { early | on | rw | ro | off }
6018			Controls if xmon debugger is enabled. Default is off.
6019			Passing only "xmon" is equivalent to "xmon=early".
6020			early	Call xmon as early as possible on boot; xmon
6021				debugger is called from setup_arch().
6022			on	xmon debugger hooks will be installed so xmon
6023				is only called on a kernel crash. Default mode,
6024				i.e. either "ro" or "rw" mode, is controlled
6025				with CONFIG_XMON_DEFAULT_RO_MODE.
6026			rw	xmon debugger hooks will be installed so xmon
6027				is called only on a kernel crash, mode is write,
6028				meaning SPR registers, memory and, other data
6029				can be written using xmon commands.
6030			ro 	same as "rw" option above but SPR registers,
6031				memory, and other data can't be written using
6032				xmon commands.
6033			off	xmon is disabled.
6034