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kernel-parameters.txt (185306B)


      1 	acpi=		[HW,ACPI,X86,ARM64]
      2 			Advanced Configuration and Power Interface
      3 			Format: { force | on | off | strict | noirq | rsdt |
      4 				  copy_dsdt }
      5 			force -- enable ACPI if default was off
      6 			on -- enable ACPI but allow fallback to DT [arm64]
      7 			off -- disable ACPI if default was on
      8 			noirq -- do not use ACPI for IRQ routing
      9 			strict -- Be less tolerant of platforms that are not
     10 				strictly ACPI specification compliant.
     11 			rsdt -- prefer RSDT over (default) XSDT
     12 			copy_dsdt -- copy DSDT to memory
     13 			For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force"
     14 			are available
     15 
     16 			See also Documentation/power/runtime_pm.txt, pci=noacpi
     17 
     18 	acpi_apic_instance=	[ACPI, IOAPIC]
     19 			Format: <int>
     20 			2: use 2nd APIC table, if available
     21 			1,0: use 1st APIC table
     22 			default: 0
     23 
     24 	acpi_backlight=	[HW,ACPI]
     25 			acpi_backlight=vendor
     26 			acpi_backlight=video
     27 			If set to vendor, prefer vendor specific driver
     28 			(e.g. thinkpad_acpi, sony_acpi, etc.) instead
     29 			of the ACPI video.ko driver.
     30 
     31 	acpi_force_32bit_fadt_addr
     32 			force FADT to use 32 bit addresses rather than the
     33 			64 bit X_* addresses. Some firmware have broken 64
     34 			bit addresses for force ACPI ignore these and use
     35 			the older legacy 32 bit addresses.
     36 
     37 	acpica_no_return_repair [HW, ACPI]
     38 			Disable AML predefined validation mechanism
     39 			This mechanism can repair the evaluation result to make
     40 			the return objects more ACPI specification compliant.
     41 			This option is useful for developers to identify the
     42 			root cause of an AML interpreter issue when the issue
     43 			has something to do with the repair mechanism.
     44 
     45 	acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
     46 	acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
     47 			Format: <int>
     48 			CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
     49 			debug output.  Bits in debug_layer correspond to a
     50 			_COMPONENT in an ACPI source file, e.g.,
     51 			    #define _COMPONENT ACPI_PCI_COMPONENT
     52 			Bits in debug_level correspond to a level in
     53 			ACPI_DEBUG_PRINT statements, e.g.,
     54 			    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
     55 			The debug_level mask defaults to "info".  See
     56 			Documentation/acpi/debug.txt for more information about
     57 			debug layers and levels.
     58 
     59 			Enable processor driver info messages:
     60 			    acpi.debug_layer=0x20000000
     61 			Enable PCI/PCI interrupt routing info messages:
     62 			    acpi.debug_layer=0x400000
     63 			Enable AML "Debug" output, i.e., stores to the Debug
     64 			object while interpreting AML:
     65 			    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
     66 			Enable all messages related to ACPI hardware:
     67 			    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
     68 
     69 			Some values produce so much output that the system is
     70 			unusable.  The "log_buf_len" parameter may be useful
     71 			if you need to capture more output.
     72 
     73 	acpi_enforce_resources=	[ACPI]
     74 			{ strict | lax | no }
     75 			Check for resource conflicts between native drivers
     76 			and ACPI OperationRegions (SystemIO and SystemMemory
     77 			only). IO ports and memory declared in ACPI might be
     78 			used by the ACPI subsystem in arbitrary AML code and
     79 			can interfere with legacy drivers.
     80 			strict (default): access to resources claimed by ACPI
     81 			is denied; legacy drivers trying to access reserved
     82 			resources will fail to bind to device using them.
     83 			lax: access to resources claimed by ACPI is allowed;
     84 			legacy drivers trying to access reserved resources
     85 			will bind successfully but a warning message is logged.
     86 			no: ACPI OperationRegions are not marked as reserved,
     87 			no further checks are performed.
     88 
     89 	acpi_force_table_verification	[HW,ACPI]
     90 			Enable table checksum verification during early stage.
     91 			By default, this is disabled due to x86 early mapping
     92 			size limitation.
     93 
     94 	acpi_irq_balance [HW,ACPI]
     95 			ACPI will balance active IRQs
     96 			default in APIC mode
     97 
     98 	acpi_irq_nobalance [HW,ACPI]
     99 			ACPI will not move active IRQs (default)
    100 			default in PIC mode
    101 
    102 	acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
    103 			Format: <irq>,<irq>...
    104 
    105 	acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
    106 			use by PCI
    107 			Format: <irq>,<irq>...
    108 
    109 	acpi_mask_gpe=	[HW,ACPI]
    110 			Due to the existence of _Lxx/_Exx, some GPEs triggered
    111 			by unsupported hardware/firmware features can result in
    112 			GPE floodings that cannot be automatically disabled by
    113 			the GPE dispatcher.
    114 			This facility can be used to prevent such uncontrolled
    115 			GPE floodings.
    116 			Format: <int>
    117 
    118 	acpi_no_auto_serialize	[HW,ACPI]
    119 			Disable auto-serialization of AML methods
    120 			AML control methods that contain the opcodes to create
    121 			named objects will be marked as "Serialized" by the
    122 			auto-serialization feature.
    123 			This feature is enabled by default.
    124 			This option allows to turn off the feature.
    125 
    126 	acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kdump
    127 			   kernels.
    128 
    129 	acpi_no_static_ssdt	[HW,ACPI]
    130 			Disable installation of static SSDTs at early boot time
    131 			By default, SSDTs contained in the RSDT/XSDT will be
    132 			installed automatically and they will appear under
    133 			/sys/firmware/acpi/tables.
    134 			This option turns off this feature.
    135 			Note that specifying this option does not affect
    136 			dynamic table installation which will install SSDT
    137 			tables to /sys/firmware/acpi/tables/dynamic.
    138 
    139 	acpi_rsdp=	[ACPI,EFI,KEXEC]
    140 			Pass the RSDP address to the kernel, mostly used
    141 			on machines running EFI runtime service to boot the
    142 			second kernel for kdump.
    143 
    144 	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
    145 			Format: To spoof as Windows 98: ="Microsoft Windows"
    146 
    147 	acpi_rev_override [ACPI] Override the _REV object to return 5 (instead
    148 			of 2 which is mandated by ACPI 6) as the supported ACPI
    149 			specification revision (when using this switch, it may
    150 			be necessary to carry out a cold reboot _twice_ in a
    151 			row to make it take effect on the platform firmware).
    152 
    153 	acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
    154 			acpi_osi="string1"	# add string1
    155 			acpi_osi="!string2"	# remove string2
    156 			acpi_osi=!*		# remove all strings
    157 			acpi_osi=!		# disable all built-in OS vendor
    158 						  strings
    159 			acpi_osi=!!		# enable all built-in OS vendor
    160 						  strings
    161 			acpi_osi=		# disable all strings
    162 
    163 			'acpi_osi=!' can be used in combination with single or
    164 			multiple 'acpi_osi="string1"' to support specific OS
    165 			vendor string(s).  Note that such command can only
    166 			affect the default state of the OS vendor strings, thus
    167 			it cannot affect the default state of the feature group
    168 			strings and the current state of the OS vendor strings,
    169 			specifying it multiple times through kernel command line
    170 			is meaningless.  This command is useful when one do not
    171 			care about the state of the feature group strings which
    172 			should be controlled by the OSPM.
    173 			Examples:
    174 			  1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
    175 			     to 'acpi_osi="Windows 2000" acpi_osi=!', they all
    176 			     can make '_OSI("Windows 2000")' TRUE.
    177 
    178 			'acpi_osi=' cannot be used in combination with other
    179 			'acpi_osi=' command lines, the _OSI method will not
    180 			exist in the ACPI namespace.  NOTE that such command can
    181 			only affect the _OSI support state, thus specifying it
    182 			multiple times through kernel command line is also
    183 			meaningless.
    184 			Examples:
    185 			  1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
    186 			     FALSE.
    187 
    188 			'acpi_osi=!*' can be used in combination with single or
    189 			multiple 'acpi_osi="string1"' to support specific
    190 			string(s).  Note that such command can affect the
    191 			current state of both the OS vendor strings and the
    192 			feature group strings, thus specifying it multiple times
    193 			through kernel command line is meaningful.  But it may
    194 			still not able to affect the final state of a string if
    195 			there are quirks related to this string.  This command
    196 			is useful when one want to control the state of the
    197 			feature group strings to debug BIOS issues related to
    198 			the OSPM features.
    199 			Examples:
    200 			  1. 'acpi_osi="Module Device" acpi_osi=!*' can make
    201 			     '_OSI("Module Device")' FALSE.
    202 			  2. 'acpi_osi=!* acpi_osi="Module Device"' can make
    203 			     '_OSI("Module Device")' TRUE.
    204 			  3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
    205 			     equivalent to
    206 			     'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
    207 			     and
    208 			     'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
    209 			     they all will make '_OSI("Windows 2000")' TRUE.
    210 
    211 	acpi_pm_good	[X86]
    212 			Override the pmtimer bug detection: force the kernel
    213 			to assume that this machine's pmtimer latches its value
    214 			and always returns good values.
    215 
    216 	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
    217 			Format: { level | edge | high | low }
    218 
    219 	acpi_skip_timer_override [HW,ACPI]
    220 			Recognize and ignore IRQ0/pin2 Interrupt Override.
    221 			For broken nForce2 BIOS resulting in XT-PIC timer.
    222 
    223 	acpi_sleep=	[HW,ACPI] Sleep options
    224 			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
    225 				  old_ordering, nonvs, sci_force_enable, nobl }
    226 			See Documentation/power/video.txt for information on
    227 			s3_bios and s3_mode.
    228 			s3_beep is for debugging; it makes the PC's speaker beep
    229 			as soon as the kernel's real-mode entry point is called.
    230 			s4_nohwsig prevents ACPI hardware signature from being
    231 			used during resume from hibernation.
    232 			old_ordering causes the ACPI 1.0 ordering of the _PTS
    233 			control method, with respect to putting devices into
    234 			low power states, to be enforced (the ACPI 2.0 ordering
    235 			of _PTS is used by default).
    236 			nonvs prevents the kernel from saving/restoring the
    237 			ACPI NVS memory during suspend/hibernation and resume.
    238 			sci_force_enable causes the kernel to set SCI_EN directly
    239 			on resume from S1/S3 (which is against the ACPI spec,
    240 			but some broken systems don't work without it).
    241 			nobl causes the internal blacklist of systems known to
    242 			behave incorrectly in some ways with respect to system
    243 			suspend and resume to be ignored (use wisely).
    244 
    245 	acpi_use_timer_override [HW,ACPI]
    246 			Use timer override. For some broken Nvidia NF5 boards
    247 			that require a timer override, but don't have HPET
    248 
    249 	add_efi_memmap	[EFI; X86] Include EFI memory map in
    250 			kernel's map of available physical RAM.
    251 
    252 	agp=		[AGP]
    253 			{ off | try_unsupported }
    254 			off: disable AGP support
    255 			try_unsupported: try to drive unsupported chipsets
    256 				(may crash computer or cause data corruption)
    257 
    258 	ALSA		[HW,ALSA]
    259 			See Documentation/sound/alsa-configuration.rst
    260 
    261 	alignment=	[KNL,ARM]
    262 			Allow the default userspace alignment fault handler
    263 			behaviour to be specified.  Bit 0 enables warnings,
    264 			bit 1 enables fixups, and bit 2 sends a segfault.
    265 
    266 	align_va_addr=	[X86-64]
    267 			Align virtual addresses by clearing slice [14:12] when
    268 			allocating a VMA at process creation time. This option
    269 			gives you up to 3% performance improvement on AMD F15h
    270 			machines (where it is enabled by default) for a
    271 			CPU-intensive style benchmark, and it can vary highly in
    272 			a microbenchmark depending on workload and compiler.
    273 
    274 			32: only for 32-bit processes
    275 			64: only for 64-bit processes
    276 			on: enable for both 32- and 64-bit processes
    277 			off: disable for both 32- and 64-bit processes
    278 
    279 	alloc_snapshot	[FTRACE]
    280 			Allocate the ftrace snapshot buffer on boot up when the
    281 			main buffer is allocated. This is handy if debugging
    282 			and you need to use tracing_snapshot() on boot up, and
    283 			do not want to use tracing_snapshot_alloc() as it needs
    284 			to be done where GFP_KERNEL allocations are allowed.
    285 
    286 	amd_iommu=	[HW,X86-64]
    287 			Pass parameters to the AMD IOMMU driver in the system.
    288 			Possible values are:
    289 			fullflush - enable flushing of IO/TLB entries when
    290 				    they are unmapped. Otherwise they are
    291 				    flushed before they will be reused, which
    292 				    is a lot of faster
    293 			off	  - do not initialize any AMD IOMMU found in
    294 				    the system
    295 			force_isolation - Force device isolation for all
    296 					  devices. The IOMMU driver is not
    297 					  allowed anymore to lift isolation
    298 					  requirements as needed. This option
    299 					  does not override iommu=pt
    300 
    301 	amd_iommu_dump=	[HW,X86-64]
    302 			Enable AMD IOMMU driver option to dump the ACPI table
    303 			for AMD IOMMU. With this option enabled, AMD IOMMU
    304 			driver will print ACPI tables for AMD IOMMU during
    305 			IOMMU initialization.
    306 
    307 	amd_iommu_intr=	[HW,X86-64]
    308 			Specifies one of the following AMD IOMMU interrupt
    309 			remapping modes:
    310 			legacy     - Use legacy interrupt remapping mode.
    311 			vapic      - Use virtual APIC mode, which allows IOMMU
    312 			             to inject interrupts directly into guest.
    313 			             This mode requires kvm-amd.avic=1.
    314 			             (Default when IOMMU HW support is present.)
    315 
    316 	amijoy.map=	[HW,JOY] Amiga joystick support
    317 			Map of devices attached to JOY0DAT and JOY1DAT
    318 			Format: <a>,<b>
    319 			See also Documentation/input/joydev/joystick.rst
    320 
    321 	analog.map=	[HW,JOY] Analog joystick and gamepad support
    322 			Specifies type or capabilities of an analog joystick
    323 			connected to one of 16 gameports
    324 			Format: <type1>,<type2>,..<type16>
    325 
    326 	apc=		[HW,SPARC]
    327 			Power management functions (SPARCstation-4/5 + deriv.)
    328 			Format: noidle
    329 			Disable APC CPU standby support. SPARCstation-Fox does
    330 			not play well with APC CPU idle - disable it if you have
    331 			APC and your system crashes randomly.
    332 
    333 	apic=		[APIC,X86] Advanced Programmable Interrupt Controller
    334 			Change the output verbosity while booting
    335 			Format: { quiet (default) | verbose | debug }
    336 			Change the amount of debugging information output
    337 			when initialising the APIC and IO-APIC components.
    338 			For X86-32, this can also be used to specify an APIC
    339 			driver name.
    340 			Format: apic=driver_name
    341 			Examples: apic=bigsmp
    342 
    343 	apic_extnmi=	[APIC,X86] External NMI delivery setting
    344 			Format: { bsp (default) | all | none }
    345 			bsp:  External NMI is delivered only to CPU 0
    346 			all:  External NMIs are broadcast to all CPUs as a
    347 			      backup of CPU 0
    348 			none: External NMI is masked for all CPUs. This is
    349 			      useful so that a dump capture kernel won't be
    350 			      shot down by NMI
    351 
    352 	autoconf=	[IPV6]
    353 			See Documentation/networking/ipv6.txt.
    354 
    355 	show_lapic=	[APIC,X86] Advanced Programmable Interrupt Controller
    356 			Limit apic dumping. The parameter defines the maximal
    357 			number of local apics being dumped. Also it is possible
    358 			to set it to "all" by meaning -- no limit here.
    359 			Format: { 1 (default) | 2 | ... | all }.
    360 			The parameter valid if only apic=debug or
    361 			apic=verbose is specified.
    362 			Example: apic=debug show_lapic=all
    363 
    364 	apm=		[APM] Advanced Power Management
    365 			See header of arch/x86/kernel/apm_32.c.
    366 
    367 	arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
    368 			Format: <io>,<irq>,<nodeID>
    369 
    370 	ataflop=	[HW,M68k]
    371 
    372 	atarimouse=	[HW,MOUSE] Atari Mouse
    373 
    374 	atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
    375 			EzKey and similar keyboards
    376 
    377 	atkbd.reset=	[HW] Reset keyboard during initialization
    378 
    379 	atkbd.set=	[HW] Select keyboard code set
    380 			Format: <int> (2 = AT (default), 3 = PS/2)
    381 
    382 	atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
    383 			keyboards
    384 
    385 	atkbd.softraw=	[HW] Choose between synthetic and real raw mode
    386 			Format: <bool> (0 = real, 1 = synthetic (default))
    387 
    388 	atkbd.softrepeat= [HW]
    389 			Use software keyboard repeat
    390 
    391 	audit=		[KNL] Enable the audit sub-system
    392 			Format: { "0" | "1" | "off" | "on" }
    393 			0 | off - kernel audit is disabled and can not be
    394 			    enabled until the next reboot
    395 			unset - kernel audit is initialized but disabled and
    396 			    will be fully enabled by the userspace auditd.
    397 			1 | on - kernel audit is initialized and partially
    398 			    enabled, storing at most audit_backlog_limit
    399 			    messages in RAM until it is fully enabled by the
    400 			    userspace auditd.
    401 			Default: unset
    402 
    403 	audit_backlog_limit= [KNL] Set the audit queue size limit.
    404 			Format: <int> (must be >=0)
    405 			Default: 64
    406 
    407 	bau=		[X86_UV] Enable the BAU on SGI UV.  The default
    408 			behavior is to disable the BAU (i.e. bau=0).
    409 			Format: { "0" | "1" }
    410 			0 - Disable the BAU.
    411 			1 - Enable the BAU.
    412 			unset - Disable the BAU.
    413 
    414 	baycom_epp=	[HW,AX25]
    415 			Format: <io>,<mode>
    416 
    417 	baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
    418 			Format: <io>,<mode>
    419 			See header of drivers/net/hamradio/baycom_par.c.
    420 
    421 	baycom_ser_fdx=	[HW,AX25]
    422 			BayCom Serial Port AX.25 Modem (Full Duplex Mode)
    423 			Format: <io>,<irq>,<mode>[,<baud>]
    424 			See header of drivers/net/hamradio/baycom_ser_fdx.c.
    425 
    426 	baycom_ser_hdx=	[HW,AX25]
    427 			BayCom Serial Port AX.25 Modem (Half Duplex Mode)
    428 			Format: <io>,<irq>,<mode>
    429 			See header of drivers/net/hamradio/baycom_ser_hdx.c.
    430 
    431 	blkdevparts=	Manual partition parsing of block device(s) for
    432 			embedded devices based on command line input.
    433 			See Documentation/block/cmdline-partition.txt
    434 
    435 	boot_delay=	Milliseconds to delay each printk during boot.
    436 			Values larger than 10 seconds (10000) are changed to
    437 			no delay (0).
    438 			Format: integer
    439 
    440 	bootmem_debug	[KNL] Enable bootmem allocator debug messages.
    441 
    442 	bert_disable	[ACPI]
    443 			Disable BERT OS support on buggy BIOSes.
    444 
    445 	bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
    446 	bttv.radio=	Most important insmod options are available as
    447 			kernel args too.
    448 	bttv.pll=	See Documentation/media/v4l-drivers/bttv.rst
    449 	bttv.tuner=
    450 
    451 	bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
    452 			firmware feature for flushing multiple hpte entries
    453 			at a time.
    454 
    455 	c101=		[NET] Moxa C101 synchronous serial card
    456 
    457 	cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
    458 			Sometimes CPU hardware bugs make them report the cache
    459 			size incorrectly. The kernel will attempt work arounds
    460 			to fix known problems, but for some CPUs it is not
    461 			possible to determine what the correct size should be.
    462 			This option provides an override for these situations.
    463 
    464 	carrier_timeout=
    465 			[NET] Specifies amount of time (in seconds) that
    466 			the kernel should wait for a network carrier. By default
    467 			it waits 120 seconds.
    468 
    469 	ca_keys=	[KEYS] This parameter identifies a specific key(s) on
    470 			the system trusted keyring to be used for certificate
    471 			trust validation.
    472 			format: { id:<keyid> | builtin }
    473 
    474 	cca=		[MIPS] Override the kernel pages' cache coherency
    475 			algorithm.  Accepted values range from 0 to 7
    476 			inclusive. See arch/mips/include/asm/pgtable-bits.h
    477 			for platform specific values (SB1, Loongson3 and
    478 			others).
    479 
    480 	ccw_timeout_log	[S390]
    481 			See Documentation/s390/CommonIO for details.
    482 
    483 	cgroup_disable=	[KNL] Disable a particular controller
    484 			Format: {name of the controller(s) to disable}
    485 			The effects of cgroup_disable=foo are:
    486 			- foo isn't auto-mounted if you mount all cgroups in
    487 			  a single hierarchy
    488 			- foo isn't visible as an individually mountable
    489 			  subsystem
    490 			{Currently only "memory" controller deal with this and
    491 			cut the overhead, others just disable the usage. So
    492 			only cgroup_disable=memory is actually worthy}
    493 
    494 	cgroup_no_v1=	[KNL] Disable cgroup controllers and named hierarchies in v1
    495 			Format: { { controller | "all" | "named" }
    496 			          [,{ controller | "all" | "named" }...] }
    497 			Like cgroup_disable, but only applies to cgroup v1;
    498 			the blacklisted controllers remain available in cgroup2.
    499 			"all" blacklists all controllers and "named" disables
    500 			named mounts. Specifying both "all" and "named" disables
    501 			all v1 hierarchies.
    502 
    503 	cgroup.memory=	[KNL] Pass options to the cgroup memory controller.
    504 			Format: <string>
    505 			nosocket -- Disable socket memory accounting.
    506 			nokmem -- Disable kernel memory accounting.
    507 
    508 	checkreqprot	[SELINUX] Set initial checkreqprot flag value.
    509 			Format: { "0" | "1" }
    510 			See security/selinux/Kconfig help text.
    511 			0 -- check protection applied by kernel (includes
    512 				any implied execute protection).
    513 			1 -- check protection requested by application.
    514 			Default value is set via a kernel config option.
    515 			Value can be changed at runtime via
    516 				/selinux/checkreqprot.
    517 
    518 	cio_ignore=	[S390]
    519 			See Documentation/s390/CommonIO for details.
    520 	clk_ignore_unused
    521 			[CLK]
    522 			Prevents the clock framework from automatically gating
    523 			clocks that have not been explicitly enabled by a Linux
    524 			device driver but are enabled in hardware at reset or
    525 			by the bootloader/firmware. Note that this does not
    526 			force such clocks to be always-on nor does it reserve
    527 			those clocks in any way. This parameter is useful for
    528 			debug and development, but should not be needed on a
    529 			platform with proper driver support.  For more
    530 			information, see Documentation/driver-api/clk.rst.
    531 
    532 	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
    533 			[Deprecated]
    534 			Forces specified clocksource (if available) to be used
    535 			when calculating gettimeofday(). If specified
    536 			clocksource is not available, it defaults to PIT.
    537 			Format: { pit | tsc | cyclone | pmtmr }
    538 
    539 	clocksource=	Override the default clocksource
    540 			Format: <string>
    541 			Override the default clocksource and use the clocksource
    542 			with the name specified.
    543 			Some clocksource names to choose from, depending on
    544 			the platform:
    545 			[all] jiffies (this is the base, fallback clocksource)
    546 			[ACPI] acpi_pm
    547 			[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
    548 				pxa_timer,timer3,32k_counter,timer0_1
    549 			[X86-32] pit,hpet,tsc;
    550 				scx200_hrt on Geode; cyclone on IBM x440
    551 			[MIPS] MIPS
    552 			[PARISC] cr16
    553 			[S390] tod
    554 			[SH] SuperH
    555 			[SPARC64] tick
    556 			[X86-64] hpet,tsc
    557 
    558 	clocksource.arm_arch_timer.evtstrm=
    559 			[ARM,ARM64]
    560 			Format: <bool>
    561 			Enable/disable the eventstream feature of the ARM
    562 			architected timer so that code using WFE-based polling
    563 			loops can be debugged more effectively on production
    564 			systems.
    565 
    566 	clearcpuid=BITNUM [X86]
    567 			Disable CPUID feature X for the kernel. See
    568 			arch/x86/include/asm/cpufeatures.h for the valid bit
    569 			numbers. Note the Linux specific bits are not necessarily
    570 			stable over kernel options, but the vendor specific
    571 			ones should be.
    572 			Also note that user programs calling CPUID directly
    573 			or using the feature without checking anything
    574 			will still see it. This just prevents it from
    575 			being used by the kernel or shown in /proc/cpuinfo.
    576 			Also note the kernel might malfunction if you disable
    577 			some critical bits.
    578 
    579 	cma=nn[MG]@[start[MG][-end[MG]]]
    580 			[ARM,X86,KNL]
    581 			Sets the size of kernel global memory area for
    582 			contiguous memory allocations and optionally the
    583 			placement constraint by the physical address range of
    584 			memory allocations. A value of 0 disables CMA
    585 			altogether. For more information, see
    586 			include/linux/dma-contiguous.h
    587 
    588 	cmo_free_hint=	[PPC] Format: { yes | no }
    589 			Specify whether pages are marked as being inactive
    590 			when they are freed.  This is used in CMO environments
    591 			to determine OS memory pressure for page stealing by
    592 			a hypervisor.
    593 			Default: yes
    594 
    595 	coherent_pool=nn[KMG]	[ARM,KNL]
    596 			Sets the size of memory pool for coherent, atomic dma
    597 			allocations, by default set to 256K.
    598 
    599 	com20020=	[HW,NET] ARCnet - COM20020 chipset
    600 			Format:
    601 			<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
    602 
    603 	com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
    604 			Format: <io>[,<irq>]
    605 
    606 	com90xx=	[HW,NET]
    607 			ARCnet - COM90xx chipset (memory-mapped buffers)
    608 			Format: <io>[,<irq>[,<memstart>]]
    609 
    610 	condev=		[HW,S390] console device
    611 	conmode=
    612 
    613 	console=	[KNL] Output console device and options.
    614 
    615 		tty<n>	Use the virtual console device <n>.
    616 
    617 		ttyS<n>[,options]
    618 		ttyUSB0[,options]
    619 			Use the specified serial port.  The options are of
    620 			the form "bbbbpnf", where "bbbb" is the baud rate,
    621 			"p" is parity ("n", "o", or "e"), "n" is number of
    622 			bits, and "f" is flow control ("r" for RTS or
    623 			omit it).  Default is "9600n8".
    624 
    625 			See Documentation/admin-guide/serial-console.rst for more
    626 			information.  See
    627 			Documentation/networking/netconsole.txt for an
    628 			alternative.
    629 
    630 		uart[8250],io,<addr>[,options]
    631 		uart[8250],mmio,<addr>[,options]
    632 		uart[8250],mmio16,<addr>[,options]
    633 		uart[8250],mmio32,<addr>[,options]
    634 		uart[8250],0x<addr>[,options]
    635 			Start an early, polled-mode console on the 8250/16550
    636 			UART at the specified I/O port or MMIO address,
    637 			switching to the matching ttyS device later.
    638 			MMIO inter-register address stride is either 8-bit
    639 			(mmio), 16-bit (mmio16), or 32-bit (mmio32).
    640 			If none of [io|mmio|mmio16|mmio32], <addr> is assumed
    641 			to be equivalent to 'mmio'. 'options' are specified in
    642 			the same format described for ttyS above; if unspecified,
    643 			the h/w is not re-initialized.
    644 
    645 		hvc<n>	Use the hypervisor console device <n>. This is for
    646 			both Xen and PowerPC hypervisors.
    647 
    648 		If the device connected to the port is not a TTY but a braille
    649 		device, prepend "brl," before the device type, for instance
    650 			console=brl,ttyS0
    651 		For now, only VisioBraille is supported.
    652 
    653 	console_msg_format=
    654 			[KNL] Change console messages format
    655 		default
    656 			By default we print messages on consoles in
    657 			"[time stamp] text\n" format (time stamp may not be
    658 			printed, depending on CONFIG_PRINTK_TIME or
    659 			`printk_time' param).
    660 		syslog
    661 			Switch to syslog format: "<%u>[time stamp] text\n"
    662 			IOW, each message will have a facility and loglevel
    663 			prefix. The format is similar to one used by syslog()
    664 			syscall, or to executing "dmesg -S --raw" or to reading
    665 			from /proc/kmsg.
    666 
    667 	consoleblank=	[KNL] The console blank (screen saver) timeout in
    668 			seconds. A value of 0 disables the blank timer.
    669 			Defaults to 0.
    670 
    671 	coredump_filter=
    672 			[KNL] Change the default value for
    673 			/proc/<pid>/coredump_filter.
    674 			See also Documentation/filesystems/proc.txt.
    675 
    676 	coresight_cpu_debug.enable
    677 			[ARM,ARM64]
    678 			Format: <bool>
    679 			Enable/disable the CPU sampling based debugging.
    680 			0: default value, disable debugging
    681 			1: enable debugging at boot time
    682 
    683 	cpuidle.off=1	[CPU_IDLE]
    684 			disable the cpuidle sub-system
    685 
    686 	cpuidle.governor=
    687 			[CPU_IDLE] Name of the cpuidle governor to use.
    688 
    689 	cpufreq.off=1	[CPU_FREQ]
    690 			disable the cpufreq sub-system
    691 
    692 	cpu_init_udelay=N
    693 			[X86] Delay for N microsec between assert and de-assert
    694 			of APIC INIT to start processors.  This delay occurs
    695 			on every CPU online, such as boot, and resume from suspend.
    696 			Default: 10000
    697 
    698 	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
    699 			Format:
    700 			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
    701 
    702 	crashkernel=size[KMG][@offset[KMG]]
    703 			[KNL] Using kexec, Linux can switch to a 'crash kernel'
    704 			upon panic. This parameter reserves the physical
    705 			memory region [offset, offset + size] for that kernel
    706 			image. If '@offset' is omitted, then a suitable offset
    707 			is selected automatically. Check
    708 			Documentation/kdump/kdump.txt for further details.
    709 
    710 	crashkernel=range1:size1[,range2:size2,...][@offset]
    711 			[KNL] Same as above, but depends on the memory
    712 			in the running system. The syntax of range is
    713 			start-[end] where start and end are both
    714 			a memory unit (amount[KMG]). See also
    715 			Documentation/kdump/kdump.txt for an example.
    716 
    717 	crashkernel=size[KMG],high
    718 			[KNL, x86_64] range could be above 4G. Allow kernel
    719 			to allocate physical memory region from top, so could
    720 			be above 4G if system have more than 4G ram installed.
    721 			Otherwise memory region will be allocated below 4G, if
    722 			available.
    723 			It will be ignored if crashkernel=X is specified.
    724 	crashkernel=size[KMG],low
    725 			[KNL, x86_64] range under 4G. When crashkernel=X,high
    726 			is passed, kernel could allocate physical memory region
    727 			above 4G, that cause second kernel crash on system
    728 			that require some amount of low memory, e.g. swiotlb
    729 			requires at least 64M+32K low memory, also enough extra
    730 			low memory is needed to make sure DMA buffers for 32-bit
    731 			devices won't run out. Kernel would try to allocate at
    732 			at least 256M below 4G automatically.
    733 			This one let user to specify own low range under 4G
    734 			for second kernel instead.
    735 			0: to disable low allocation.
    736 			It will be ignored when crashkernel=X,high is not used
    737 			or memory reserved is below 4G.
    738 
    739 	cryptomgr.notests
    740 			[KNL] Disable crypto self-tests
    741 
    742 	cs89x0_dma=	[HW,NET]
    743 			Format: <dma>
    744 
    745 	cs89x0_media=	[HW,NET]
    746 			Format: { rj45 | aui | bnc }
    747 
    748 	dasd=		[HW,NET]
    749 			See header of drivers/s390/block/dasd_devmap.c.
    750 
    751 	db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
    752 			(one device per port)
    753 			Format: <port#>,<type>
    754 			See also Documentation/input/devices/joystick-parport.rst
    755 
    756 	ddebug_query=	[KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
    757 			time. See
    758 			Documentation/admin-guide/dynamic-debug-howto.rst for
    759 			details.  Deprecated, see dyndbg.
    760 
    761 	debug		[KNL] Enable kernel debugging (events log level).
    762 
    763 	debug_boot_weak_hash
    764 			[KNL] Enable printing [hashed] pointers early in the
    765 			boot sequence.  If enabled, we use a weak hash instead
    766 			of siphash to hash pointers.  Use this option if you are
    767 			seeing instances of '(___ptrval___)') and need to see a
    768 			value (hashed pointer) instead. Cryptographically
    769 			insecure, please do not use on production kernels.
    770 
    771 	debug_locks_verbose=
    772 			[KNL] verbose self-tests
    773 			Format=<0|1>
    774 			Print debugging info while doing the locking API
    775 			self-tests.
    776 			We default to 0 (no extra messages), setting it to
    777 			1 will print _a lot_ more information - normally
    778 			only useful to kernel developers.
    779 
    780 	debug_objects	[KNL] Enable object debugging
    781 
    782 	no_debug_objects
    783 			[KNL] Disable object debugging
    784 
    785 	debug_guardpage_minorder=
    786 			[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
    787 			parameter allows control of the order of pages that will
    788 			be intentionally kept free (and hence protected) by the
    789 			buddy allocator. Bigger value increase the probability
    790 			of catching random memory corruption, but reduce the
    791 			amount of memory for normal system use. The maximum
    792 			possible value is MAX_ORDER/2.  Setting this parameter
    793 			to 1 or 2 should be enough to identify most random
    794 			memory corruption problems caused by bugs in kernel or
    795 			driver code when a CPU writes to (or reads from) a
    796 			random memory location. Note that there exists a class
    797 			of memory corruptions problems caused by buggy H/W or
    798 			F/W or by drivers badly programing DMA (basically when
    799 			memory is written at bus level and the CPU MMU is
    800 			bypassed) which are not detectable by
    801 			CONFIG_DEBUG_PAGEALLOC, hence this option will not help
    802 			tracking down these problems.
    803 
    804 	debug_pagealloc=
    805 			[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
    806 			parameter enables the feature at boot time. In
    807 			default, it is disabled. We can avoid allocating huge
    808 			chunk of memory for debug pagealloc if we don't enable
    809 			it at boot time and the system will work mostly same
    810 			with the kernel built without CONFIG_DEBUG_PAGEALLOC.
    811 			on: enable the feature
    812 
    813 	debugpat	[X86] Enable PAT debugging
    814 
    815 	decnet.addr=	[HW,NET]
    816 			Format: <area>[,<node>]
    817 			See also Documentation/networking/decnet.txt.
    818 
    819 	default_hugepagesz=
    820 			[same as hugepagesz=] The size of the default
    821 			HugeTLB page size. This is the size represented by
    822 			the legacy /proc/ hugepages APIs, used for SHM, and
    823 			default size when mounting hugetlbfs filesystems.
    824 			Defaults to the default architecture's huge page size
    825 			if not specified.
    826 
    827 	deferred_probe_timeout=
    828 			[KNL] Debugging option to set a timeout in seconds for
    829 			deferred probe to give up waiting on dependencies to
    830 			probe. Only specific dependencies (subsystems or
    831 			drivers) that have opted in will be ignored. A timeout of 0
    832 			will timeout at the end of initcalls. This option will also
    833 			dump out devices still on the deferred probe list after
    834 			retrying.
    835 
    836 	dhash_entries=	[KNL]
    837 			Set number of hash buckets for dentry cache.
    838 
    839 	disable_1tb_segments [PPC]
    840 			Disables the use of 1TB hash page table segments. This
    841 			causes the kernel to fall back to 256MB segments which
    842 			can be useful when debugging issues that require an SLB
    843 			miss to occur.
    844 
    845 	disable=	[IPV6]
    846 			See Documentation/networking/ipv6.txt.
    847 
    848 	hardened_usercopy=
    849                         [KNL] Under CONFIG_HARDENED_USERCOPY, whether
    850                         hardening is enabled for this boot. Hardened
    851                         usercopy checking is used to protect the kernel
    852                         from reading or writing beyond known memory
    853                         allocation boundaries as a proactive defense
    854                         against bounds-checking flaws in the kernel's
    855                         copy_to_user()/copy_from_user() interface.
    856                 on      Perform hardened usercopy checks (default).
    857                 off     Disable hardened usercopy checks.
    858 
    859 	disable_radix	[PPC]
    860 			Disable RADIX MMU mode on POWER9
    861 
    862 	disable_cpu_apicid= [X86,APIC,SMP]
    863 			Format: <int>
    864 			The number of initial APIC ID for the
    865 			corresponding CPU to be disabled at boot,
    866 			mostly used for the kdump 2nd kernel to
    867 			disable BSP to wake up multiple CPUs without
    868 			causing system reset or hang due to sending
    869 			INIT from AP to BSP.
    870 
    871 	perf_v4_pmi=	[X86,INTEL]
    872 			Format: <bool>
    873 			Disable Intel PMU counter freezing feature.
    874 			The feature only exists starting from
    875 			Arch Perfmon v4 (Skylake and newer).
    876 
    877 	disable_ddw	[PPC/PSERIES]
    878 			Disable Dynamic DMA Window support. Use this if
    879 			to workaround buggy firmware.
    880 
    881 	disable_ipv6=	[IPV6]
    882 			See Documentation/networking/ipv6.txt.
    883 
    884 	disable_mtrr_cleanup [X86]
    885 			The kernel tries to adjust MTRR layout from continuous
    886 			to discrete, to make X server driver able to add WB
    887 			entry later. This parameter disables that.
    888 
    889 	disable_mtrr_trim [X86, Intel and AMD only]
    890 			By default the kernel will trim any uncacheable
    891 			memory out of your available memory pool based on
    892 			MTRR settings.  This parameter disables that behavior,
    893 			possibly causing your machine to run very slowly.
    894 
    895 	disable_timer_pin_1 [X86]
    896 			Disable PIN 1 of APIC timer
    897 			Can be useful to work around chipset bugs.
    898 
    899 	dis_ucode_ldr	[X86] Disable the microcode loader.
    900 
    901 	dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
    902 			this option disables the debugging code at boot.
    903 
    904 	dma_debug_entries=<number>
    905 			This option allows to tune the number of preallocated
    906 			entries for DMA-API debugging code. One entry is
    907 			required per DMA-API allocation. Use this if the
    908 			DMA-API debugging code disables itself because the
    909 			architectural default is too low.
    910 
    911 	dma_debug_driver=<driver_name>
    912 			With this option the DMA-API debugging driver
    913 			filter feature can be enabled at boot time. Just
    914 			pass the driver to filter for as the parameter.
    915 			The filter can be disabled or changed to another
    916 			driver later using sysfs.
    917 
    918 	driver_async_probe=  [KNL]
    919 			List of driver names to be probed asynchronously.
    920 			Format: <driver_name1>,<driver_name2>...
    921 
    922 	drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
    923 			Broken monitors, graphic adapters, KVMs and EDIDless
    924 			panels may send no or incorrect EDID data sets.
    925 			This parameter allows to specify an EDID data sets
    926 			in the /lib/firmware directory that are used instead.
    927 			Generic built-in EDID data sets are used, if one of
    928 			edid/1024x768.bin, edid/1280x1024.bin,
    929 			edid/1680x1050.bin, or edid/1920x1080.bin is given
    930 			and no file with the same name exists. Details and
    931 			instructions how to build your own EDID data are
    932 			available in Documentation/EDID/HOWTO.txt. An EDID
    933 			data set will only be used for a particular connector,
    934 			if its name and a colon are prepended to the EDID
    935 			name. Each connector may use a unique EDID data
    936 			set by separating the files with a comma.  An EDID
    937 			data set with no connector name will be used for
    938 			any connectors not explicitly specified.
    939 
    940 	dscc4.setup=	[NET]
    941 
    942 	dt_cpu_ftrs=	[PPC]
    943 			Format: {"off" | "known"}
    944 			Control how the dt_cpu_ftrs device-tree binding is
    945 			used for CPU feature discovery and setup (if it
    946 			exists).
    947 			off: Do not use it, fall back to legacy cpu table.
    948 			known: Do not pass through unknown features to guests
    949 			or userspace, only those that the kernel is aware of.
    950 
    951 	dump_apple_properties	[X86]
    952 			Dump name and content of EFI device properties on
    953 			x86 Macs.  Useful for driver authors to determine
    954 			what data is available or for reverse-engineering.
    955 
    956 	dyndbg[="val"]		[KNL,DYNAMIC_DEBUG]
    957 	module.dyndbg[="val"]
    958 			Enable debug messages at boot time.  See
    959 			Documentation/admin-guide/dynamic-debug-howto.rst
    960 			for details.
    961 
    962 	nompx		[X86] Disables Intel Memory Protection Extensions.
    963 			See Documentation/x86/intel_mpx.txt for more
    964 			information about the feature.
    965 
    966 	nopku		[X86] Disable Memory Protection Keys CPU feature found
    967 			in some Intel CPUs.
    968 
    969 	module.async_probe [KNL]
    970 			Enable asynchronous probe on this module.
    971 
    972 	early_ioremap_debug [KNL]
    973 			Enable debug messages in early_ioremap support. This
    974 			is useful for tracking down temporary early mappings
    975 			which are not unmapped.
    976 
    977 	earlycon=	[KNL] Output early console device and options.
    978 
    979 			[ARM64] The early console is determined by the
    980 			stdout-path property in device tree's chosen node,
    981 			or determined by the ACPI SPCR table.
    982 
    983 			[X86] When used with no options the early console is
    984 			determined by the ACPI SPCR table.
    985 
    986 		cdns,<addr>[,options]
    987 			Start an early, polled-mode console on a Cadence
    988 			(xuartps) serial port at the specified address. Only
    989 			supported option is baud rate. If baud rate is not
    990 			specified, the serial port must already be setup and
    991 			configured.
    992 
    993 		uart[8250],io,<addr>[,options]
    994 		uart[8250],mmio,<addr>[,options]
    995 		uart[8250],mmio32,<addr>[,options]
    996 		uart[8250],mmio32be,<addr>[,options]
    997 		uart[8250],0x<addr>[,options]
    998 			Start an early, polled-mode console on the 8250/16550
    999 			UART at the specified I/O port or MMIO address.
   1000 			MMIO inter-register address stride is either 8-bit
   1001 			(mmio) or 32-bit (mmio32 or mmio32be).
   1002 			If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
   1003 			to be equivalent to 'mmio'. 'options' are specified
   1004 			in the same format described for "console=ttyS<n>"; if
   1005 			unspecified, the h/w is not initialized.
   1006 
   1007 		pl011,<addr>
   1008 		pl011,mmio32,<addr>
   1009 			Start an early, polled-mode console on a pl011 serial
   1010 			port at the specified address. The pl011 serial port
   1011 			must already be setup and configured. Options are not
   1012 			yet supported.  If 'mmio32' is specified, then only
   1013 			the driver will use only 32-bit accessors to read/write
   1014 			the device registers.
   1015 
   1016 		meson,<addr>
   1017 			Start an early, polled-mode console on a meson serial
   1018 			port at the specified address. The serial port must
   1019 			already be setup and configured. Options are not yet
   1020 			supported.
   1021 
   1022 		msm_serial,<addr>
   1023 			Start an early, polled-mode console on an msm serial
   1024 			port at the specified address. The serial port
   1025 			must already be setup and configured. Options are not
   1026 			yet supported.
   1027 
   1028 		msm_serial_dm,<addr>
   1029 			Start an early, polled-mode console on an msm serial
   1030 			dm port at the specified address. The serial port
   1031 			must already be setup and configured. Options are not
   1032 			yet supported.
   1033 
   1034 		owl,<addr>
   1035 			Start an early, polled-mode console on a serial port
   1036 			of an Actions Semi SoC, such as S500 or S900, at the
   1037 			specified address. The serial port must already be
   1038 			setup and configured. Options are not yet supported.
   1039 
   1040 		rda,<addr>
   1041 			Start an early, polled-mode console on a serial port
   1042 			of an RDA Micro SoC, such as RDA8810PL, at the
   1043 			specified address. The serial port must already be
   1044 			setup and configured. Options are not yet supported.
   1045 
   1046 		smh	Use ARM semihosting calls for early console.
   1047 
   1048 		s3c2410,<addr>
   1049 		s3c2412,<addr>
   1050 		s3c2440,<addr>
   1051 		s3c6400,<addr>
   1052 		s5pv210,<addr>
   1053 		exynos4210,<addr>
   1054 			Use early console provided by serial driver available
   1055 			on Samsung SoCs, requires selecting proper type and
   1056 			a correct base address of the selected UART port. The
   1057 			serial port must already be setup and configured.
   1058 			Options are not yet supported.
   1059 
   1060 		lantiq,<addr>
   1061 			Start an early, polled-mode console on a lantiq serial
   1062 			(lqasc) port at the specified address. The serial port
   1063 			must already be setup and configured. Options are not
   1064 			yet supported.
   1065 
   1066 		lpuart,<addr>
   1067 		lpuart32,<addr>
   1068 			Use early console provided by Freescale LP UART driver
   1069 			found on Freescale Vybrid and QorIQ LS1021A processors.
   1070 			A valid base address must be provided, and the serial
   1071 			port must already be setup and configured.
   1072 
   1073 		ar3700_uart,<addr>
   1074 			Start an early, polled-mode console on the
   1075 			Armada 3700 serial port at the specified
   1076 			address. The serial port must already be setup
   1077 			and configured. Options are not yet supported.
   1078 
   1079 		qcom_geni,<addr>
   1080 			Start an early, polled-mode console on a Qualcomm
   1081 			Generic Interface (GENI) based serial port at the
   1082 			specified address. The serial port must already be
   1083 			setup and configured. Options are not yet supported.
   1084 
   1085 		efifb,[options]
   1086 			Start an early, unaccelerated console on the EFI
   1087 			memory mapped framebuffer (if available). On cache
   1088 			coherent non-x86 systems that use system memory for
   1089 			the framebuffer, pass the 'ram' option so that it is
   1090 			mapped with the correct attributes.
   1091 
   1092 	earlyprintk=	[X86,SH,ARM,M68k,S390]
   1093 			earlyprintk=vga
   1094 			earlyprintk=sclp
   1095 			earlyprintk=xen
   1096 			earlyprintk=serial[,ttySn[,baudrate]]
   1097 			earlyprintk=serial[,0x...[,baudrate]]
   1098 			earlyprintk=ttySn[,baudrate]
   1099 			earlyprintk=dbgp[debugController#]
   1100 			earlyprintk=pciserial[,force],bus:device.function[,baudrate]
   1101 			earlyprintk=xdbc[xhciController#]
   1102 
   1103 			earlyprintk is useful when the kernel crashes before
   1104 			the normal console is initialized. It is not enabled by
   1105 			default because it has some cosmetic problems.
   1106 
   1107 			Append ",keep" to not disable it when the real console
   1108 			takes over.
   1109 
   1110 			Only one of vga, efi, serial, or usb debug port can
   1111 			be used at a time.
   1112 
   1113 			Currently only ttyS0 and ttyS1 may be specified by
   1114 			name.  Other I/O ports may be explicitly specified
   1115 			on some architectures (x86 and arm at least) by
   1116 			replacing ttySn with an I/O port address, like this:
   1117 				earlyprintk=serial,0x1008,115200
   1118 			You can find the port for a given device in
   1119 			/proc/tty/driver/serial:
   1120 				2: uart:ST16650V2 port:00001008 irq:18 ...
   1121 
   1122 			Interaction with the standard serial driver is not
   1123 			very good.
   1124 
   1125 			The VGA and EFI output is eventually overwritten by
   1126 			the real console.
   1127 
   1128 			The xen output can only be used by Xen PV guests.
   1129 
   1130 			The sclp output can only be used on s390.
   1131 
   1132 			The optional "force" to "pciserial" enables use of a
   1133 			PCI device even when its classcode is not of the
   1134 			UART class.
   1135 
   1136 	edac_report=	[HW,EDAC] Control how to report EDAC event
   1137 			Format: {"on" | "off" | "force"}
   1138 			on: enable EDAC to report H/W event. May be overridden
   1139 			by other higher priority error reporting module.
   1140 			off: disable H/W event reporting through EDAC.
   1141 			force: enforce the use of EDAC to report H/W event.
   1142 			default: on.
   1143 
   1144 	ekgdboc=	[X86,KGDB] Allow early kernel console debugging
   1145 			ekgdboc=kbd
   1146 
   1147 			This is designed to be used in conjunction with
   1148 			the boot argument: earlyprintk=vga
   1149 
   1150 	edd=		[EDD]
   1151 			Format: {"off" | "on" | "skip[mbr]"}
   1152 
   1153 	efi=		[EFI]
   1154 			Format: { "old_map", "nochunk", "noruntime", "debug" }
   1155 			old_map [X86-64]: switch to the old ioremap-based EFI
   1156 			runtime services mapping. 32-bit still uses this one by
   1157 			default.
   1158 			nochunk: disable reading files in "chunks" in the EFI
   1159 			boot stub, as chunking can cause problems with some
   1160 			firmware implementations.
   1161 			noruntime : disable EFI runtime services support
   1162 			debug: enable misc debug output
   1163 
   1164 	efi_no_storage_paranoia [EFI; X86]
   1165 			Using this parameter you can use more than 50% of
   1166 			your efi variable storage. Use this parameter only if
   1167 			you are really sure that your UEFI does sane gc and
   1168 			fulfills the spec otherwise your board may brick.
   1169 
   1170 	efi_fake_mem=	nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86]
   1171 			Add arbitrary attribute to specific memory range by
   1172 			updating original EFI memory map.
   1173 			Region of memory which aa attribute is added to is
   1174 			from ss to ss+nn.
   1175 			If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
   1176 			is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
   1177 			attribute is added to range 0x100000000-0x180000000 and
   1178 			0x10a0000000-0x1120000000.
   1179 
   1180 			Using this parameter you can do debugging of EFI memmap
   1181 			related feature. For example, you can do debugging of
   1182 			Address Range Mirroring feature even if your box
   1183 			doesn't support it.
   1184 
   1185 	efivar_ssdt=	[EFI; X86] Name of an EFI variable that contains an SSDT
   1186 			that is to be dynamically loaded by Linux. If there are
   1187 			multiple variables with the same name but with different
   1188 			vendor GUIDs, all of them will be loaded. See
   1189 			Documentation/acpi/ssdt-overlays.txt for details.
   1190 
   1191 
   1192 	eisa_irq_edge=	[PARISC,HW]
   1193 			See header of drivers/parisc/eisa.c.
   1194 
   1195 	elanfreq=	[X86-32]
   1196 			See comment before function elanfreq_setup() in
   1197 			arch/x86/kernel/cpu/cpufreq/elanfreq.c.
   1198 
   1199 	elevator=	[IOSCHED]
   1200 			Format: { "mq-deadline" | "kyber" | "bfq" }
   1201 			See Documentation/block/deadline-iosched.txt,
   1202 			Documentation/block/kyber-iosched.txt and
   1203 			Documentation/block/bfq-iosched.txt for details.
   1204 
   1205 	elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
   1206 			Specifies physical address of start of kernel core
   1207 			image elf header and optionally the size. Generally
   1208 			kexec loader will pass this option to capture kernel.
   1209 			See Documentation/kdump/kdump.txt for details.
   1210 
   1211 	enable_mtrr_cleanup [X86]
   1212 			The kernel tries to adjust MTRR layout from continuous
   1213 			to discrete, to make X server driver able to add WB
   1214 			entry later. This parameter enables that.
   1215 
   1216 	enable_timer_pin_1 [X86]
   1217 			Enable PIN 1 of APIC timer
   1218 			Can be useful to work around chipset bugs
   1219 			(in particular on some ATI chipsets).
   1220 			The kernel tries to set a reasonable default.
   1221 
   1222 	enforcing	[SELINUX] Set initial enforcing status.
   1223 			Format: {"0" | "1"}
   1224 			See security/selinux/Kconfig help text.
   1225 			0 -- permissive (log only, no denials).
   1226 			1 -- enforcing (deny and log).
   1227 			Default value is 0.
   1228 			Value can be changed at runtime via /selinux/enforce.
   1229 
   1230 	erst_disable	[ACPI]
   1231 			Disable Error Record Serialization Table (ERST)
   1232 			support.
   1233 
   1234 	ether=		[HW,NET] Ethernet cards parameters
   1235 			This option is obsoleted by the "netdev=" option, which
   1236 			has equivalent usage. See its documentation for details.
   1237 
   1238 	evm=		[EVM]
   1239 			Format: { "fix" }
   1240 			Permit 'security.evm' to be updated regardless of
   1241 			current integrity status.
   1242 
   1243 	failslab=
   1244 	fail_page_alloc=
   1245 	fail_make_request=[KNL]
   1246 			General fault injection mechanism.
   1247 			Format: <interval>,<probability>,<space>,<times>
   1248 			See also Documentation/fault-injection/.
   1249 
   1250 	floppy=		[HW]
   1251 			See Documentation/blockdev/floppy.txt.
   1252 
   1253 	force_pal_cache_flush
   1254 			[IA-64] Avoid check_sal_cache_flush which may hang on
   1255 			buggy SAL_CACHE_FLUSH implementations. Using this
   1256 			parameter will force ia64_sal_cache_flush to call
   1257 			ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
   1258 
   1259 	forcepae	[X86-32]
   1260 			Forcefully enable Physical Address Extension (PAE).
   1261 			Many Pentium M systems disable PAE but may have a
   1262 			functionally usable PAE implementation.
   1263 			Warning: use of this parameter will taint the kernel
   1264 			and may cause unknown problems.
   1265 
   1266 	ftrace=[tracer]
   1267 			[FTRACE] will set and start the specified tracer
   1268 			as early as possible in order to facilitate early
   1269 			boot debugging.
   1270 
   1271 	ftrace_dump_on_oops[=orig_cpu]
   1272 			[FTRACE] will dump the trace buffers on oops.
   1273 			If no parameter is passed, ftrace will dump
   1274 			buffers of all CPUs, but if you pass orig_cpu, it will
   1275 			dump only the buffer of the CPU that triggered the
   1276 			oops.
   1277 
   1278 	ftrace_filter=[function-list]
   1279 			[FTRACE] Limit the functions traced by the function
   1280 			tracer at boot up. function-list is a comma separated
   1281 			list of functions. This list can be changed at run
   1282 			time by the set_ftrace_filter file in the debugfs
   1283 			tracing directory.
   1284 
   1285 	ftrace_notrace=[function-list]
   1286 			[FTRACE] Do not trace the functions specified in
   1287 			function-list. This list can be changed at run time
   1288 			by the set_ftrace_notrace file in the debugfs
   1289 			tracing directory.
   1290 
   1291 	ftrace_graph_filter=[function-list]
   1292 			[FTRACE] Limit the top level callers functions traced
   1293 			by the function graph tracer at boot up.
   1294 			function-list is a comma separated list of functions
   1295 			that can be changed at run time by the
   1296 			set_graph_function file in the debugfs tracing directory.
   1297 
   1298 	ftrace_graph_notrace=[function-list]
   1299 			[FTRACE] Do not trace from the functions specified in
   1300 			function-list.  This list is a comma separated list of
   1301 			functions that can be changed at run time by the
   1302 			set_graph_notrace file in the debugfs tracing directory.
   1303 
   1304 	ftrace_graph_max_depth=<uint>
   1305 			[FTRACE] Used with the function graph tracer. This is
   1306 			the max depth it will trace into a function. This value
   1307 			can be changed at run time by the max_graph_depth file
   1308 			in the tracefs tracing directory. default: 0 (no limit)
   1309 
   1310 	gamecon.map[2|3]=
   1311 			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
   1312 			support via parallel port (up to 5 devices per port)
   1313 			Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
   1314 			See also Documentation/input/devices/joystick-parport.rst
   1315 
   1316 	gamma=		[HW,DRM]
   1317 
   1318 	gart_fix_e820=	[X86_64] disable the fix e820 for K8 GART
   1319 			Format: off | on
   1320 			default: on
   1321 
   1322 	gcov_persist=	[GCOV] When non-zero (default), profiling data for
   1323 			kernel modules is saved and remains accessible via
   1324 			debugfs, even when the module is unloaded/reloaded.
   1325 			When zero, profiling data is discarded and associated
   1326 			debugfs files are removed at module unload time.
   1327 
   1328 	goldfish	[X86] Enable the goldfish android emulator platform.
   1329 			Don't use this when you are not running on the
   1330 			android emulator
   1331 
   1332 	gpt		[EFI] Forces disk with valid GPT signature but
   1333 			invalid Protective MBR to be treated as GPT. If the
   1334 			primary GPT is corrupted, it enables the backup/alternate
   1335 			GPT to be used instead.
   1336 
   1337 	grcan.enable0=	[HW] Configuration of physical interface 0. Determines
   1338 			the "Enable 0" bit of the configuration register.
   1339 			Format: 0 | 1
   1340 			Default: 0
   1341 	grcan.enable1=	[HW] Configuration of physical interface 1. Determines
   1342 			the "Enable 0" bit of the configuration register.
   1343 			Format: 0 | 1
   1344 			Default: 0
   1345 	grcan.select=	[HW] Select which physical interface to use.
   1346 			Format: 0 | 1
   1347 			Default: 0
   1348 	grcan.txsize=	[HW] Sets the size of the tx buffer.
   1349 			Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
   1350 			Default: 1024
   1351 	grcan.rxsize=	[HW] Sets the size of the rx buffer.
   1352 			Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
   1353 			Default: 1024
   1354 
   1355 	gpio-mockup.gpio_mockup_ranges
   1356 			[HW] Sets the ranges of gpiochip of for this device.
   1357 			Format: <start1>,<end1>,<start2>,<end2>...
   1358 
   1359 	hardlockup_all_cpu_backtrace=
   1360 			[KNL] Should the hard-lockup detector generate
   1361 			backtraces on all cpus.
   1362 			Format: <integer>
   1363 
   1364 	hashdist=	[KNL,NUMA] Large hashes allocated during boot
   1365 			are distributed across NUMA nodes.  Defaults on
   1366 			for 64-bit NUMA, off otherwise.
   1367 			Format: 0 | 1 (for off | on)
   1368 
   1369 	hcl=		[IA-64] SGI's Hardware Graph compatibility layer
   1370 
   1371 	hd=		[EIDE] (E)IDE hard drive subsystem geometry
   1372 			Format: <cyl>,<head>,<sect>
   1373 
   1374 	hest_disable	[ACPI]
   1375 			Disable Hardware Error Source Table (HEST) support;
   1376 			corresponding firmware-first mode error processing
   1377 			logic will be disabled.
   1378 
   1379 	highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
   1380 			size of <nn>. This works even on boxes that have no
   1381 			highmem otherwise. This also works to reduce highmem
   1382 			size on bigger boxes.
   1383 
   1384 	highres=	[KNL] Enable/disable high resolution timer mode.
   1385 			Valid parameters: "on", "off"
   1386 			Default: "on"
   1387 
   1388 	hisax=		[HW,ISDN]
   1389 			See Documentation/isdn/README.HiSax.
   1390 
   1391 	hlt		[BUGS=ARM,SH]
   1392 
   1393 	hpet=		[X86-32,HPET] option to control HPET usage
   1394 			Format: { enable (default) | disable | force |
   1395 				verbose }
   1396 			disable: disable HPET and use PIT instead
   1397 			force: allow force enabled of undocumented chips (ICH4,
   1398 				VIA, nVidia)
   1399 			verbose: show contents of HPET registers during setup
   1400 
   1401 	hpet_mmap=	[X86, HPET_MMAP] Allow userspace to mmap HPET
   1402 			registers.  Default set by CONFIG_HPET_MMAP_DEFAULT.
   1403 
   1404 	hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
   1405 	hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
   1406 			On x86-64 and powerpc, this option can be specified
   1407 			multiple times interleaved with hugepages= to reserve
   1408 			huge pages of different sizes. Valid pages sizes on
   1409 			x86-64 are 2M (when the CPU supports "pse") and 1G
   1410 			(when the CPU supports the "pdpe1gb" cpuinfo flag).
   1411 
   1412 	hung_task_panic=
   1413 			[KNL] Should the hung task detector generate panics.
   1414 			Format: <integer>
   1415 
   1416 			A nonzero value instructs the kernel to panic when a
   1417 			hung task is detected. The default value is controlled
   1418 			by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
   1419 			option. The value selected by this boot parameter can
   1420 			be changed later by the kernel.hung_task_panic sysctl.
   1421 
   1422 	hvc_iucv=	[S390]	Number of z/VM IUCV hypervisor console (HVC)
   1423 				terminal devices. Valid values: 0..8
   1424 	hvc_iucv_allow=	[S390]	Comma-separated list of z/VM user IDs.
   1425 				If specified, z/VM IUCV HVC accepts connections
   1426 				from listed z/VM user IDs only.
   1427 
   1428 	hv_nopvspin	[X86,HYPER_V] Disables the paravirt spinlock optimizations
   1429 				      which allow the hypervisor to 'idle' the
   1430 				      guest on lock contention.
   1431 
   1432 	keep_bootcon	[KNL]
   1433 			Do not unregister boot console at start. This is only
   1434 			useful for debugging when something happens in the window
   1435 			between unregistering the boot console and initializing
   1436 			the real console.
   1437 
   1438 	i2c_bus=	[HW]	Override the default board specific I2C bus speed
   1439 				or register an additional I2C bus that is not
   1440 				registered from board initialization code.
   1441 				Format:
   1442 				<bus_id>,<clkrate>
   1443 
   1444 	i8042.debug	[HW] Toggle i8042 debug mode
   1445 	i8042.unmask_kbd_data
   1446 			[HW] Enable printing of interrupt data from the KBD port
   1447 			     (disabled by default, and as a pre-condition
   1448 			     requires that i8042.debug=1 be enabled)
   1449 	i8042.direct	[HW] Put keyboard port into non-translated mode
   1450 	i8042.dumbkbd	[HW] Pretend that controller can only read data from
   1451 			     keyboard and cannot control its state
   1452 			     (Don't attempt to blink the leds)
   1453 	i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
   1454 	i8042.nokbd	[HW] Don't check/create keyboard port
   1455 	i8042.noloop	[HW] Disable the AUX Loopback command while probing
   1456 			     for the AUX port
   1457 	i8042.nomux	[HW] Don't check presence of an active multiplexing
   1458 			     controller
   1459 	i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
   1460 			     controllers
   1461 	i8042.notimeout	[HW] Ignore timeout condition signalled by controller
   1462 	i8042.reset	[HW] Reset the controller during init, cleanup and
   1463 			     suspend-to-ram transitions, only during s2r
   1464 			     transitions, or never reset
   1465 			Format: { 1 | Y | y | 0 | N | n }
   1466 			1, Y, y: always reset controller
   1467 			0, N, n: don't ever reset controller
   1468 			Default: only on s2r transitions on x86; most other
   1469 			architectures force reset to be always executed
   1470 	i8042.unlock	[HW] Unlock (ignore) the keylock
   1471 	i8042.kbdreset	[HW] Reset device connected to KBD port
   1472 
   1473 	i810=		[HW,DRM]
   1474 
   1475 	i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
   1476 			indicates that the driver is running on unsupported
   1477 			hardware.
   1478 	i8k.force	[HW] Activate i8k driver even if SMM BIOS signature
   1479 			does not match list of supported models.
   1480 	i8k.power_status
   1481 			[HW] Report power status in /proc/i8k
   1482 			(disabled by default)
   1483 	i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN
   1484 			capability is set.
   1485 
   1486 	i915.invert_brightness=
   1487 			[DRM] Invert the sense of the variable that is used to
   1488 			set the brightness of the panel backlight. Normally a
   1489 			brightness value of 0 indicates backlight switched off,
   1490 			and the maximum of the brightness value sets the backlight
   1491 			to maximum brightness. If this parameter is set to 0
   1492 			(default) and the machine requires it, or this parameter
   1493 			is set to 1, a brightness value of 0 sets the backlight
   1494 			to maximum brightness, and the maximum of the brightness
   1495 			value switches the backlight off.
   1496 			-1 -- never invert brightness
   1497 			 0 -- machine default
   1498 			 1 -- force brightness inversion
   1499 
   1500 	icn=		[HW,ISDN]
   1501 			Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
   1502 
   1503 	ide-core.nodma=	[HW] (E)IDE subsystem
   1504 			Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
   1505 			.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
   1506 			.cdrom .chs .ignore_cable are additional options
   1507 			See Documentation/ide/ide.txt.
   1508 
   1509 	ide-generic.probe-mask= [HW] (E)IDE subsystem
   1510 			Format: <int>
   1511 			Probe mask for legacy ISA IDE ports.  Depending on
   1512 			platform up to 6 ports are supported, enabled by
   1513 			setting corresponding bits in the mask to 1.  The
   1514 			default value is 0x0, which has a special meaning.
   1515 			On systems that have PCI, it triggers scanning the
   1516 			PCI bus for the first and the second port, which
   1517 			are then probed.  On systems without PCI the value
   1518 			of 0x0 enables probing the two first ports as if it
   1519 			was 0x3.
   1520 
   1521 	ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
   1522 			Claim all unknown PCI IDE storage controllers.
   1523 
   1524 	idle=		[X86]
   1525 			Format: idle=poll, idle=halt, idle=nomwait
   1526 			Poll forces a polling idle loop that can slightly
   1527 			improve the performance of waking up a idle CPU, but
   1528 			will use a lot of power and make the system run hot.
   1529 			Not recommended.
   1530 			idle=halt: Halt is forced to be used for CPU idle.
   1531 			In such case C2/C3 won't be used again.
   1532 			idle=nomwait: Disable mwait for CPU C-states
   1533 
   1534 	ieee754=	[MIPS] Select IEEE Std 754 conformance mode
   1535 			Format: { strict | legacy | 2008 | relaxed }
   1536 			Default: strict
   1537 
   1538 			Choose which programs will be accepted for execution
   1539 			based on the IEEE 754 NaN encoding(s) supported by
   1540 			the FPU and the NaN encoding requested with the value
   1541 			of an ELF file header flag individually set by each
   1542 			binary.  Hardware implementations are permitted to
   1543 			support either or both of the legacy and the 2008 NaN
   1544 			encoding mode.
   1545 
   1546 			Available settings are as follows:
   1547 			strict	accept binaries that request a NaN encoding
   1548 				supported by the FPU
   1549 			legacy	only accept legacy-NaN binaries, if supported
   1550 				by the FPU
   1551 			2008	only accept 2008-NaN binaries, if supported
   1552 				by the FPU
   1553 			relaxed	accept any binaries regardless of whether
   1554 				supported by the FPU
   1555 
   1556 			The FPU emulator is always able to support both NaN
   1557 			encodings, so if no FPU hardware is present or it has
   1558 			been disabled with 'nofpu', then the settings of
   1559 			'legacy' and '2008' strap the emulator accordingly,
   1560 			'relaxed' straps the emulator for both legacy-NaN and
   1561 			2008-NaN, whereas 'strict' enables legacy-NaN only on
   1562 			legacy processors and both NaN encodings on MIPS32 or
   1563 			MIPS64 CPUs.
   1564 
   1565 			The setting for ABS.fmt/NEG.fmt instruction execution
   1566 			mode generally follows that for the NaN encoding,
   1567 			except where unsupported by hardware.
   1568 
   1569 	ignore_loglevel	[KNL]
   1570 			Ignore loglevel setting - this will print /all/
   1571 			kernel messages to the console. Useful for debugging.
   1572 			We also add it as printk module parameter, so users
   1573 			could change it dynamically, usually by
   1574 			/sys/module/printk/parameters/ignore_loglevel.
   1575 
   1576 	ignore_rlimit_data
   1577 			Ignore RLIMIT_DATA setting for data mappings,
   1578 			print warning at first misuse.  Can be changed via
   1579 			/sys/module/kernel/parameters/ignore_rlimit_data.
   1580 
   1581 	ihash_entries=	[KNL]
   1582 			Set number of hash buckets for inode cache.
   1583 
   1584 	ima_appraise=	[IMA] appraise integrity measurements
   1585 			Format: { "off" | "enforce" | "fix" | "log" }
   1586 			default: "enforce"
   1587 
   1588 	ima_appraise_tcb [IMA]
   1589 			The builtin appraise policy appraises all files
   1590 			owned by uid=0.
   1591 
   1592 	ima_canonical_fmt [IMA]
   1593 			Use the canonical format for the binary runtime
   1594 			measurements, instead of host native format.
   1595 
   1596 	ima_hash=	[IMA]
   1597 			Format: { md5 | sha1 | rmd160 | sha256 | sha384
   1598 				   | sha512 | ... }
   1599 			default: "sha1"
   1600 
   1601 			The list of supported hash algorithms is defined
   1602 			in crypto/hash_info.h.
   1603 
   1604 	ima_policy=	[IMA]
   1605 			The builtin policies to load during IMA setup.
   1606 			Format: "tcb | appraise_tcb | secure_boot |
   1607 				 fail_securely"
   1608 
   1609 			The "tcb" policy measures all programs exec'd, files
   1610 			mmap'd for exec, and all files opened with the read
   1611 			mode bit set by either the effective uid (euid=0) or
   1612 			uid=0.
   1613 
   1614 			The "appraise_tcb" policy appraises the integrity of
   1615 			all files owned by root. (This is the equivalent
   1616 			of ima_appraise_tcb.)
   1617 
   1618 			The "secure_boot" policy appraises the integrity
   1619 			of files (eg. kexec kernel image, kernel modules,
   1620 			firmware, policy, etc) based on file signatures.
   1621 
   1622 			The "fail_securely" policy forces file signature
   1623 			verification failure also on privileged mounted
   1624 			filesystems with the SB_I_UNVERIFIABLE_SIGNATURE
   1625 			flag.
   1626 
   1627 	ima_tcb		[IMA] Deprecated.  Use ima_policy= instead.
   1628 			Load a policy which meets the needs of the Trusted
   1629 			Computing Base.  This means IMA will measure all
   1630 			programs exec'd, files mmap'd for exec, and all files
   1631 			opened for read by uid=0.
   1632 
   1633 	ima_template=	[IMA]
   1634 			Select one of defined IMA measurements template formats.
   1635 			Formats: { "ima" | "ima-ng" | "ima-sig" }
   1636 			Default: "ima-ng"
   1637 
   1638 	ima_template_fmt=
   1639 			[IMA] Define a custom template format.
   1640 			Format: { "field1|...|fieldN" }
   1641 
   1642 	ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
   1643 			Format: <min_file_size>
   1644 			Set the minimal file size for using asynchronous hash.
   1645 			If left unspecified, ahash usage is disabled.
   1646 
   1647 			ahash performance varies for different data sizes on
   1648 			different crypto accelerators. This option can be used
   1649 			to achieve the best performance for a particular HW.
   1650 
   1651 	ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
   1652 			Format: <bufsize>
   1653 			Set hashing buffer size. Default: 4k.
   1654 
   1655 			ahash performance varies for different chunk sizes on
   1656 			different crypto accelerators. This option can be used
   1657 			to achieve best performance for particular HW.
   1658 
   1659 	init=		[KNL]
   1660 			Format: <full_path>
   1661 			Run specified binary instead of /sbin/init as init
   1662 			process.
   1663 
   1664 	initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
   1665 			for working out where the kernel is dying during
   1666 			startup.
   1667 
   1668 	initcall_blacklist=  [KNL] Do not execute a comma-separated list of
   1669 			initcall functions.  Useful for debugging built-in
   1670 			modules and initcalls.
   1671 
   1672 	initrd=		[BOOT] Specify the location of the initial ramdisk
   1673 
   1674 	init_pkru=	[x86] Specify the default memory protection keys rights
   1675 			register contents for all processes.  0x55555554 by
   1676 			default (disallow access to all but pkey 0).  Can
   1677 			override in debugfs after boot.
   1678 
   1679 	inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
   1680 			Format: <irq>
   1681 
   1682 	int_pln_enable	[x86] Enable power limit notification interrupt
   1683 
   1684 	integrity_audit=[IMA]
   1685 			Format: { "0" | "1" }
   1686 			0 -- basic integrity auditing messages. (Default)
   1687 			1 -- additional integrity auditing messages.
   1688 
   1689 	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
   1690 		on
   1691 			Enable intel iommu driver.
   1692 		off
   1693 			Disable intel iommu driver.
   1694 		igfx_off [Default Off]
   1695 			By default, gfx is mapped as normal device. If a gfx
   1696 			device has a dedicated DMAR unit, the DMAR unit is
   1697 			bypassed by not enabling DMAR with this option. In
   1698 			this case, gfx device will use physical address for
   1699 			DMA.
   1700 		forcedac [x86_64]
   1701 			With this option iommu will not optimize to look
   1702 			for io virtual address below 32-bit forcing dual
   1703 			address cycle on pci bus for cards supporting greater
   1704 			than 32-bit addressing. The default is to look
   1705 			for translation below 32-bit and if not available
   1706 			then look in the higher range.
   1707 		strict [Default Off]
   1708 			With this option on every unmap_single operation will
   1709 			result in a hardware IOTLB flush operation as opposed
   1710 			to batching them for performance.
   1711 		sp_off [Default Off]
   1712 			By default, super page will be supported if Intel IOMMU
   1713 			has the capability. With this option, super page will
   1714 			not be supported.
   1715 		sm_on [Default Off]
   1716 			By default, scalable mode will be disabled even if the
   1717 			hardware advertises that it has support for the scalable
   1718 			mode translation. With this option set, scalable mode
   1719 			will be used on hardware which claims to support it.
   1720 		tboot_noforce [Default Off]
   1721 			Do not force the Intel IOMMU enabled under tboot.
   1722 			By default, tboot will force Intel IOMMU on, which
   1723 			could harm performance of some high-throughput
   1724 			devices like 40GBit network cards, even if identity
   1725 			mapping is enabled.
   1726 			Note that using this option lowers the security
   1727 			provided by tboot because it makes the system
   1728 			vulnerable to DMA attacks.
   1729 
   1730 	intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
   1731 			0	disables intel_idle and fall back on acpi_idle.
   1732 			1 to 9	specify maximum depth of C-state.
   1733 
   1734 	intel_pstate=	[X86]
   1735 			disable
   1736 			  Do not enable intel_pstate as the default
   1737 			  scaling driver for the supported processors
   1738 			passive
   1739 			  Use intel_pstate as a scaling driver, but configure it
   1740 			  to work with generic cpufreq governors (instead of
   1741 			  enabling its internal governor).  This mode cannot be
   1742 			  used along with the hardware-managed P-states (HWP)
   1743 			  feature.
   1744 			force
   1745 			  Enable intel_pstate on systems that prohibit it by default
   1746 			  in favor of acpi-cpufreq. Forcing the intel_pstate driver
   1747 			  instead of acpi-cpufreq may disable platform features, such
   1748 			  as thermal controls and power capping, that rely on ACPI
   1749 			  P-States information being indicated to OSPM and therefore
   1750 			  should be used with caution. This option does not work with
   1751 			  processors that aren't supported by the intel_pstate driver
   1752 			  or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
   1753 			no_hwp
   1754 			  Do not enable hardware P state control (HWP)
   1755 			  if available.
   1756 			hwp_only
   1757 			  Only load intel_pstate on systems which support
   1758 			  hardware P state control (HWP) if available.
   1759 			support_acpi_ppc
   1760 			  Enforce ACPI _PPC performance limits. If the Fixed ACPI
   1761 			  Description Table, specifies preferred power management
   1762 			  profile as "Enterprise Server" or "Performance Server",
   1763 			  then this feature is turned on by default.
   1764 			per_cpu_perf_limits
   1765 			  Allow per-logical-CPU P-State performance control limits using
   1766 			  cpufreq sysfs interface
   1767 
   1768 	intremap=	[X86-64, Intel-IOMMU]
   1769 			on	enable Interrupt Remapping (default)
   1770 			off	disable Interrupt Remapping
   1771 			nosid	disable Source ID checking
   1772 			no_x2apic_optout
   1773 				BIOS x2APIC opt-out request will be ignored
   1774 			nopost	disable Interrupt Posting
   1775 
   1776 	iomem=		Disable strict checking of access to MMIO memory
   1777 		strict	regions from userspace.
   1778 		relaxed
   1779 
   1780 	iommu=		[x86]
   1781 		off
   1782 		force
   1783 		noforce
   1784 		biomerge
   1785 		panic
   1786 		nopanic
   1787 		merge
   1788 		nomerge
   1789 		soft
   1790 		pt		[x86]
   1791 		nopt		[x86]
   1792 		nobypass	[PPC/POWERNV]
   1793 			Disable IOMMU bypass, using IOMMU for PCI devices.
   1794 
   1795 	iommu.strict=	[ARM64] Configure TLB invalidation behaviour
   1796 			Format: { "0" | "1" }
   1797 			0 - Lazy mode.
   1798 			  Request that DMA unmap operations use deferred
   1799 			  invalidation of hardware TLBs, for increased
   1800 			  throughput at the cost of reduced device isolation.
   1801 			  Will fall back to strict mode if not supported by
   1802 			  the relevant IOMMU driver.
   1803 			1 - Strict mode (default).
   1804 			  DMA unmap operations invalidate IOMMU hardware TLBs
   1805 			  synchronously.
   1806 
   1807 	iommu.passthrough=
   1808 			[ARM64] Configure DMA to bypass the IOMMU by default.
   1809 			Format: { "0" | "1" }
   1810 			0 - Use IOMMU translation for DMA.
   1811 			1 - Bypass the IOMMU for DMA.
   1812 			unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
   1813 
   1814 	io7=		[HW] IO7 for Marvel based alpha systems
   1815 			See comment before marvel_specify_io7 in
   1816 			arch/alpha/kernel/core_marvel.c.
   1817 
   1818 	io_delay=	[X86] I/O delay method
   1819 		0x80
   1820 			Standard port 0x80 based delay
   1821 		0xed
   1822 			Alternate port 0xed based delay (needed on some systems)
   1823 		udelay
   1824 			Simple two microseconds delay
   1825 		none
   1826 			No delay
   1827 
   1828 	ip=		[IP_PNP]
   1829 			See Documentation/filesystems/nfs/nfsroot.txt.
   1830 
   1831 	irqaffinity=	[SMP] Set the default irq affinity mask
   1832 			The argument is a cpu list, as described above.
   1833 
   1834 	irqchip.gicv2_force_probe=
   1835 			[ARM, ARM64]
   1836 			Format: <bool>
   1837 			Force the kernel to look for the second 4kB page
   1838 			of a GICv2 controller even if the memory range
   1839 			exposed by the device tree is too small.
   1840 
   1841 	irqchip.gicv3_nolpi=
   1842 			[ARM, ARM64]
   1843 			Force the kernel to ignore the availability of
   1844 			LPIs (and by consequence ITSs). Intended for system
   1845 			that use the kernel as a bootloader, and thus want
   1846 			to let secondary kernels in charge of setting up
   1847 			LPIs.
   1848 
   1849 	irqchip.gicv3_pseudo_nmi= [ARM64]
   1850 			Enables support for pseudo-NMIs in the kernel. This
   1851 			requires the kernel to be built with
   1852 			CONFIG_ARM64_PSEUDO_NMI.
   1853 
   1854 	irqfixup	[HW]
   1855 			When an interrupt is not handled search all handlers
   1856 			for it. Intended to get systems with badly broken
   1857 			firmware running.
   1858 
   1859 	irqpoll		[HW]
   1860 			When an interrupt is not handled search all handlers
   1861 			for it. Also check all handlers each timer
   1862 			interrupt. Intended to get systems with badly broken
   1863 			firmware running.
   1864 
   1865 	isapnp=		[ISAPNP]
   1866 			Format: <RDP>,<reset>,<pci_scan>,<verbosity>
   1867 
   1868 	isolcpus=	[KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
   1869 			[Deprecated - use cpusets instead]
   1870 			Format: [flag-list,]<cpu-list>
   1871 
   1872 			Specify one or more CPUs to isolate from disturbances
   1873 			specified in the flag list (default: domain):
   1874 
   1875 			nohz
   1876 			  Disable the tick when a single task runs.
   1877 
   1878 			  A residual 1Hz tick is offloaded to workqueues, which you
   1879 			  need to affine to housekeeping through the global
   1880 			  workqueue's affinity configured via the
   1881 			  /sys/devices/virtual/workqueue/cpumask sysfs file, or
   1882 			  by using the 'domain' flag described below.
   1883 
   1884 			  NOTE: by default the global workqueue runs on all CPUs,
   1885 			  so to protect individual CPUs the 'cpumask' file has to
   1886 			  be configured manually after bootup.
   1887 
   1888 			domain
   1889 			  Isolate from the general SMP balancing and scheduling
   1890 			  algorithms. Note that performing domain isolation this way
   1891 			  is irreversible: it's not possible to bring back a CPU to
   1892 			  the domains once isolated through isolcpus. It's strongly
   1893 			  advised to use cpusets instead to disable scheduler load
   1894 			  balancing through the "cpuset.sched_load_balance" file.
   1895 			  It offers a much more flexible interface where CPUs can
   1896 			  move in and out of an isolated set anytime.
   1897 
   1898 			  You can move a process onto or off an "isolated" CPU via
   1899 			  the CPU affinity syscalls or cpuset.
   1900 			  <cpu number> begins at 0 and the maximum value is
   1901 			  "number of CPUs in system - 1".
   1902 
   1903 			The format of <cpu-list> is described above.
   1904 
   1905 
   1906 
   1907 	iucv=		[HW,NET]
   1908 
   1909 	ivrs_ioapic	[HW,X86_64]
   1910 			Provide an override to the IOAPIC-ID<->DEVICE-ID
   1911 			mapping provided in the IVRS ACPI table. For
   1912 			example, to map IOAPIC-ID decimal 10 to
   1913 			PCI device 00:14.0 write the parameter as:
   1914 				ivrs_ioapic[10]=00:14.0
   1915 
   1916 	ivrs_hpet	[HW,X86_64]
   1917 			Provide an override to the HPET-ID<->DEVICE-ID
   1918 			mapping provided in the IVRS ACPI table. For
   1919 			example, to map HPET-ID decimal 0 to
   1920 			PCI device 00:14.0 write the parameter as:
   1921 				ivrs_hpet[0]=00:14.0
   1922 
   1923 	ivrs_acpihid	[HW,X86_64]
   1924 			Provide an override to the ACPI-HID:UID<->DEVICE-ID
   1925 			mapping provided in the IVRS ACPI table. For
   1926 			example, to map UART-HID:UID AMD0020:0 to
   1927 			PCI device 00:14.5 write the parameter as:
   1928 				ivrs_acpihid[00:14.5]=AMD0020:0
   1929 
   1930 	js=		[HW,JOY] Analog joystick
   1931 			See Documentation/input/joydev/joystick.rst.
   1932 
   1933 	nokaslr		[KNL]
   1934 			When CONFIG_RANDOMIZE_BASE is set, this disables
   1935 			kernel and module base offset ASLR (Address Space
   1936 			Layout Randomization).
   1937 
   1938 	kasan_multi_shot
   1939 			[KNL] Enforce KASAN (Kernel Address Sanitizer) to print
   1940 			report on every invalid memory access. Without this
   1941 			parameter KASAN will print report only for the first
   1942 			invalid access.
   1943 
   1944 	keepinitrd	[HW,ARM]
   1945 
   1946 	kernelcore=	[KNL,X86,IA-64,PPC]
   1947 			Format: nn[KMGTPE] | nn% | "mirror"
   1948 			This parameter specifies the amount of memory usable by
   1949 			the kernel for non-movable allocations.  The requested
   1950 			amount is spread evenly throughout all nodes in the
   1951 			system as ZONE_NORMAL.  The remaining memory is used for
   1952 			movable memory in its own zone, ZONE_MOVABLE.  In the
   1953 			event, a node is too small to have both ZONE_NORMAL and
   1954 			ZONE_MOVABLE, kernelcore memory will take priority and
   1955 			other nodes will have a larger ZONE_MOVABLE.
   1956 
   1957 			ZONE_MOVABLE is used for the allocation of pages that
   1958 			may be reclaimed or moved by the page migration
   1959 			subsystem.  Note that allocations like PTEs-from-HighMem
   1960 			still use the HighMem zone if it exists, and the Normal
   1961 			zone if it does not.
   1962 
   1963 			It is possible to specify the exact amount of memory in
   1964 			the form of "nn[KMGTPE]", a percentage of total system
   1965 			memory in the form of "nn%", or "mirror".  If "mirror"
   1966 			option is specified, mirrored (reliable) memory is used
   1967 			for non-movable allocations and remaining memory is used
   1968 			for Movable pages.  "nn[KMGTPE]", "nn%", and "mirror"
   1969 			are exclusive, so you cannot specify multiple forms.
   1970 
   1971 	kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
   1972 			Format: <Controller#>[,poll interval]
   1973 			The controller # is the number of the ehci usb debug
   1974 			port as it is probed via PCI.  The poll interval is
   1975 			optional and is the number seconds in between
   1976 			each poll cycle to the debug port in case you need
   1977 			the functionality for interrupting the kernel with
   1978 			gdb or control-c on the dbgp connection.  When
   1979 			not using this parameter you use sysrq-g to break into
   1980 			the kernel debugger.
   1981 
   1982 	kgdboc=		[KGDB,HW] kgdb over consoles.
   1983 			Requires a tty driver that supports console polling,
   1984 			or a supported polling keyboard driver (non-usb).
   1985 			 Serial only format: <serial_device>[,baud]
   1986 			 keyboard only format: kbd
   1987 			 keyboard and serial format: kbd,<serial_device>[,baud]
   1988 			Optional Kernel mode setting:
   1989 			 kms, kbd format: kms,kbd
   1990 			 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
   1991 
   1992 	kgdbwait	[KGDB] Stop kernel execution and enter the
   1993 			kernel debugger at the earliest opportunity.
   1994 
   1995 	kmac=		[MIPS] korina ethernet MAC address.
   1996 			Configure the RouterBoard 532 series on-chip
   1997 			Ethernet adapter MAC address.
   1998 
   1999 	kmemleak=	[KNL] Boot-time kmemleak enable/disable
   2000 			Valid arguments: on, off
   2001 			Default: on
   2002 			Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
   2003 			the default is off.
   2004 
   2005 	kpti=		[ARM64] Control page table isolation of user
   2006 			and kernel address spaces.
   2007 			Default: enabled on cores which need mitigation.
   2008 			0: force disabled
   2009 			1: force enabled
   2010 
   2011 	kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
   2012 			Default is 0 (don't ignore, but inject #GP)
   2013 
   2014 	kvm.enable_vmware_backdoor=[KVM] Support VMware backdoor PV interface.
   2015 				   Default is false (don't support).
   2016 
   2017 	kvm.mmu_audit=	[KVM] This is a R/W parameter which allows audit
   2018 			KVM MMU at runtime.
   2019 			Default is 0 (off)
   2020 
   2021 	kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.
   2022 			Default is 1 (enabled)
   2023 
   2024 	kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)
   2025 			for all guests.
   2026 			Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
   2027 
   2028 	kvm-arm.vgic_v3_group0_trap=
   2029 			[KVM,ARM] Trap guest accesses to GICv3 group-0
   2030 			system registers
   2031 
   2032 	kvm-arm.vgic_v3_group1_trap=
   2033 			[KVM,ARM] Trap guest accesses to GICv3 group-1
   2034 			system registers
   2035 
   2036 	kvm-arm.vgic_v3_common_trap=
   2037 			[KVM,ARM] Trap guest accesses to GICv3 common
   2038 			system registers
   2039 
   2040 	kvm-arm.vgic_v4_enable=
   2041 			[KVM,ARM] Allow use of GICv4 for direct injection of
   2042 			LPIs.
   2043 
   2044 	kvm-intel.ept=	[KVM,Intel] Disable extended page tables
   2045 			(virtualized MMU) support on capable Intel chips.
   2046 			Default is 1 (enabled)
   2047 
   2048 	kvm-intel.emulate_invalid_guest_state=
   2049 			[KVM,Intel] Enable emulation of invalid guest states
   2050 			Default is 0 (disabled)
   2051 
   2052 	kvm-intel.flexpriority=
   2053 			[KVM,Intel] Disable FlexPriority feature (TPR shadow).
   2054 			Default is 1 (enabled)
   2055 
   2056 	kvm-intel.nested=
   2057 			[KVM,Intel] Enable VMX nesting (nVMX).
   2058 			Default is 0 (disabled)
   2059 
   2060 	kvm-intel.unrestricted_guest=
   2061 			[KVM,Intel] Disable unrestricted guest feature
   2062 			(virtualized real and unpaged mode) on capable
   2063 			Intel chips. Default is 1 (enabled)
   2064 
   2065 	kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
   2066 			CVE-2018-3620.
   2067 
   2068 			Valid arguments: never, cond, always
   2069 
   2070 			always: L1D cache flush on every VMENTER.
   2071 			cond:	Flush L1D on VMENTER only when the code between
   2072 				VMEXIT and VMENTER can leak host memory.
   2073 			never:	Disables the mitigation
   2074 
   2075 			Default is cond (do L1 cache flush in specific instances)
   2076 
   2077 	kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification
   2078 			feature (tagged TLBs) on capable Intel chips.
   2079 			Default is 1 (enabled)
   2080 
   2081 	l1tf=           [X86] Control mitigation of the L1TF vulnerability on
   2082 			      affected CPUs
   2083 
   2084 			The kernel PTE inversion protection is unconditionally
   2085 			enabled and cannot be disabled.
   2086 
   2087 			full
   2088 				Provides all available mitigations for the
   2089 				L1TF vulnerability. Disables SMT and
   2090 				enables all mitigations in the
   2091 				hypervisors, i.e. unconditional L1D flush.
   2092 
   2093 				SMT control and L1D flush control via the
   2094 				sysfs interface is still possible after
   2095 				boot.  Hypervisors will issue a warning
   2096 				when the first VM is started in a
   2097 				potentially insecure configuration,
   2098 				i.e. SMT enabled or L1D flush disabled.
   2099 
   2100 			full,force
   2101 				Same as 'full', but disables SMT and L1D
   2102 				flush runtime control. Implies the
   2103 				'nosmt=force' command line option.
   2104 				(i.e. sysfs control of SMT is disabled.)
   2105 
   2106 			flush
   2107 				Leaves SMT enabled and enables the default
   2108 				hypervisor mitigation, i.e. conditional
   2109 				L1D flush.
   2110 
   2111 				SMT control and L1D flush control via the
   2112 				sysfs interface is still possible after
   2113 				boot.  Hypervisors will issue a warning
   2114 				when the first VM is started in a
   2115 				potentially insecure configuration,
   2116 				i.e. SMT enabled or L1D flush disabled.
   2117 
   2118 			flush,nosmt
   2119 
   2120 				Disables SMT and enables the default
   2121 				hypervisor mitigation.
   2122 
   2123 				SMT control and L1D flush control via the
   2124 				sysfs interface is still possible after
   2125 				boot.  Hypervisors will issue a warning
   2126 				when the first VM is started in a
   2127 				potentially insecure configuration,
   2128 				i.e. SMT enabled or L1D flush disabled.
   2129 
   2130 			flush,nowarn
   2131 				Same as 'flush', but hypervisors will not
   2132 				warn when a VM is started in a potentially
   2133 				insecure configuration.
   2134 
   2135 			off
   2136 				Disables hypervisor mitigations and doesn't
   2137 				emit any warnings.
   2138 				It also drops the swap size and available
   2139 				RAM limit restriction on both hypervisor and
   2140 				bare metal.
   2141 
   2142 			Default is 'flush'.
   2143 
   2144 			For details see: Documentation/admin-guide/l1tf.rst
   2145 
   2146 	l2cr=		[PPC]
   2147 
   2148 	l3cr=		[PPC]
   2149 
   2150 	lapic		[X86-32,APIC] Enable the local APIC even if BIOS
   2151 			disabled it.
   2152 
   2153 	lapic=		[x86,APIC] "notscdeadline" Do not use TSC deadline
   2154 			value for LAPIC timer one-shot implementation. Default
   2155 			back to the programmable timer unit in the LAPIC.
   2156 
   2157 	lapic_timer_c2_ok	[X86,APIC] trust the local apic timer
   2158 			in C2 power state.
   2159 
   2160 	libata.dma=	[LIBATA] DMA control
   2161 			libata.dma=0	  Disable all PATA and SATA DMA
   2162 			libata.dma=1	  PATA and SATA Disk DMA only
   2163 			libata.dma=2	  ATAPI (CDROM) DMA only
   2164 			libata.dma=4	  Compact Flash DMA only
   2165 			Combinations also work, so libata.dma=3 enables DMA
   2166 			for disks and CDROMs, but not CFs.
   2167 
   2168 	libata.ignore_hpa=	[LIBATA] Ignore HPA limit
   2169 			libata.ignore_hpa=0	  keep BIOS limits (default)
   2170 			libata.ignore_hpa=1	  ignore limits, using full disk
   2171 
   2172 	libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
   2173 			when set.
   2174 			Format: <int>
   2175 
   2176 	libata.force=	[LIBATA] Force configurations.  The format is comma
   2177 			separated list of "[ID:]VAL" where ID is
   2178 			PORT[.DEVICE].  PORT and DEVICE are decimal numbers
   2179 			matching port, link or device.  Basically, it matches
   2180 			the ATA ID string printed on console by libata.  If
   2181 			the whole ID part is omitted, the last PORT and DEVICE
   2182 			values are used.  If ID hasn't been specified yet, the
   2183 			configuration applies to all ports, links and devices.
   2184 
   2185 			If only DEVICE is omitted, the parameter applies to
   2186 			the port and all links and devices behind it.  DEVICE
   2187 			number of 0 either selects the first device or the
   2188 			first fan-out link behind PMP device.  It does not
   2189 			select the host link.  DEVICE number of 15 selects the
   2190 			host link and device attached to it.
   2191 
   2192 			The VAL specifies the configuration to force.  As long
   2193 			as there's no ambiguity shortcut notation is allowed.
   2194 			For example, both 1.5 and 1.5G would work for 1.5Gbps.
   2195 			The following configurations can be forced.
   2196 
   2197 			* Cable type: 40c, 80c, short40c, unk, ign or sata.
   2198 			  Any ID with matching PORT is used.
   2199 
   2200 			* SATA link speed limit: 1.5Gbps or 3.0Gbps.
   2201 
   2202 			* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
   2203 			  udma[/][16,25,33,44,66,100,133] notation is also
   2204 			  allowed.
   2205 
   2206 			* [no]ncq: Turn on or off NCQ.
   2207 
   2208 			* [no]ncqtrim: Turn off queued DSM TRIM.
   2209 
   2210 			* nohrst, nosrst, norst: suppress hard, soft
   2211 			  and both resets.
   2212 
   2213 			* rstonce: only attempt one reset during
   2214 			  hot-unplug link recovery
   2215 
   2216 			* dump_id: dump IDENTIFY data.
   2217 
   2218 			* atapi_dmadir: Enable ATAPI DMADIR bridge support
   2219 
   2220 			* disable: Disable this device.
   2221 
   2222 			If there are multiple matching configurations changing
   2223 			the same attribute, the last one is used.
   2224 
   2225 	memblock=debug	[KNL] Enable memblock debug messages.
   2226 
   2227 	load_ramdisk=	[RAM] List of ramdisks to load from floppy
   2228 			See Documentation/blockdev/ramdisk.txt.
   2229 
   2230 	lockd.nlm_grace_period=P  [NFS] Assign grace period.
   2231 			Format: <integer>
   2232 
   2233 	lockd.nlm_tcpport=N	[NFS] Assign TCP port.
   2234 			Format: <integer>
   2235 
   2236 	lockd.nlm_timeout=T	[NFS] Assign timeout value.
   2237 			Format: <integer>
   2238 
   2239 	lockd.nlm_udpport=M	[NFS] Assign UDP port.
   2240 			Format: <integer>
   2241 
   2242 	locktorture.nreaders_stress= [KNL]
   2243 			Set the number of locking read-acquisition kthreads.
   2244 			Defaults to being automatically set based on the
   2245 			number of online CPUs.
   2246 
   2247 	locktorture.nwriters_stress= [KNL]
   2248 			Set the number of locking write-acquisition kthreads.
   2249 
   2250 	locktorture.onoff_holdoff= [KNL]
   2251 			Set time (s) after boot for CPU-hotplug testing.
   2252 
   2253 	locktorture.onoff_interval= [KNL]
   2254 			Set time (s) between CPU-hotplug operations, or
   2255 			zero to disable CPU-hotplug testing.
   2256 
   2257 	locktorture.shuffle_interval= [KNL]
   2258 			Set task-shuffle interval (jiffies).  Shuffling
   2259 			tasks allows some CPUs to go into dyntick-idle
   2260 			mode during the locktorture test.
   2261 
   2262 	locktorture.shutdown_secs= [KNL]
   2263 			Set time (s) after boot system shutdown.  This
   2264 			is useful for hands-off automated testing.
   2265 
   2266 	locktorture.stat_interval= [KNL]
   2267 			Time (s) between statistics printk()s.
   2268 
   2269 	locktorture.stutter= [KNL]
   2270 			Time (s) to stutter testing, for example,
   2271 			specifying five seconds causes the test to run for
   2272 			five seconds, wait for five seconds, and so on.
   2273 			This tests the locking primitive's ability to
   2274 			transition abruptly to and from idle.
   2275 
   2276 	locktorture.torture_type= [KNL]
   2277 			Specify the locking implementation to test.
   2278 
   2279 	locktorture.verbose= [KNL]
   2280 			Enable additional printk() statements.
   2281 
   2282 	logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
   2283 			Format: <irq>
   2284 
   2285 	loglevel=	All Kernel Messages with a loglevel smaller than the
   2286 			console loglevel will be printed to the console. It can
   2287 			also be changed with klogd or other programs. The
   2288 			loglevels are defined as follows:
   2289 
   2290 			0 (KERN_EMERG)		system is unusable
   2291 			1 (KERN_ALERT)		action must be taken immediately
   2292 			2 (KERN_CRIT)		critical conditions
   2293 			3 (KERN_ERR)		error conditions
   2294 			4 (KERN_WARNING)	warning conditions
   2295 			5 (KERN_NOTICE)		normal but significant condition
   2296 			6 (KERN_INFO)		informational
   2297 			7 (KERN_DEBUG)		debug-level messages
   2298 
   2299 	log_buf_len=n[KMG]	Sets the size of the printk ring buffer,
   2300 			in bytes.  n must be a power of two and greater
   2301 			than the minimal size. The minimal size is defined
   2302 			by LOG_BUF_SHIFT kernel config parameter. There is
   2303 			also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
   2304 			that allows to increase the default size depending on
   2305 			the number of CPUs. See init/Kconfig for more details.
   2306 
   2307 	logo.nologo	[FB] Disables display of the built-in Linux logo.
   2308 			This may be used to provide more screen space for
   2309 			kernel log messages and is useful when debugging
   2310 			kernel boot problems.
   2311 
   2312 	lp=0		[LP]	Specify parallel ports to use, e.g,
   2313 	lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
   2314 	lp=reset		first parallel port). 'lp=0' disables the
   2315 	lp=auto			printer driver. 'lp=reset' (which can be
   2316 				specified in addition to the ports) causes
   2317 				attached printers to be reset. Using
   2318 				lp=port1,port2,... specifies the parallel ports
   2319 				to associate lp devices with, starting with
   2320 				lp0. A port specification may be 'none' to skip
   2321 				that lp device, or a parport name such as
   2322 				'parport0'. Specifying 'lp=auto' instead of a
   2323 				port specification list means that device IDs
   2324 				from each port should be examined, to see if
   2325 				an IEEE 1284-compliant printer is attached; if
   2326 				so, the driver will manage that printer.
   2327 				See also header of drivers/char/lp.c.
   2328 
   2329 	lpj=n		[KNL]
   2330 			Sets loops_per_jiffy to given constant, thus avoiding
   2331 			time-consuming boot-time autodetection (up to 250 ms per
   2332 			CPU). 0 enables autodetection (default). To determine
   2333 			the correct value for your kernel, boot with normal
   2334 			autodetection and see what value is printed. Note that
   2335 			on SMP systems the preset will be applied to all CPUs,
   2336 			which is likely to cause problems if your CPUs need
   2337 			significantly divergent settings. An incorrect value
   2338 			will cause delays in the kernel to be wrong, leading to
   2339 			unpredictable I/O errors and other breakage. Although
   2340 			unlikely, in the extreme case this might damage your
   2341 			hardware.
   2342 
   2343 	ltpc=		[NET]
   2344 			Format: <io>,<irq>,<dma>
   2345 
   2346 	lsm.debug	[SECURITY] Enable LSM initialization debugging output.
   2347 
   2348 	lsm=lsm1,...,lsmN
   2349 			[SECURITY] Choose order of LSM initialization. This
   2350 			overrides CONFIG_LSM, and the "security=" parameter.
   2351 
   2352 	machvec=	[IA-64] Force the use of a particular machine-vector
   2353 			(machvec) in a generic kernel.
   2354 			Example: machvec=hpzx1_swiotlb
   2355 
   2356 	machtype=	[Loongson] Share the same kernel image file between different
   2357 			 yeeloong laptop.
   2358 			Example: machtype=lemote-yeeloong-2f-7inch
   2359 
   2360 	max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater
   2361 			than or equal to this physical address is ignored.
   2362 
   2363 	maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
   2364 			will bring up during bootup.  maxcpus=n : n >= 0 limits
   2365 			the kernel to bring up 'n' processors. Surely after
   2366 			bootup you can bring up the other plugged cpu by executing
   2367 			"echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus
   2368 			only takes effect during system bootup.
   2369 			While n=0 is a special case, it is equivalent to "nosmp",
   2370 			which also disables the IO APIC.
   2371 
   2372 	max_loop=	[LOOP] The number of loop block devices that get
   2373 	(loop.max_loop)	unconditionally pre-created at init time. The default
   2374 			number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
   2375 			of statically allocating a predefined number, loop
   2376 			devices can be requested on-demand with the
   2377 			/dev/loop-control interface.
   2378 
   2379 	mce		[X86-32] Machine Check Exception
   2380 
   2381 	mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.txt
   2382 
   2383 	md=		[HW] RAID subsystems devices and level
   2384 			See Documentation/admin-guide/md.rst.
   2385 
   2386 	mdacon=		[MDA]
   2387 			Format: <first>,<last>
   2388 			Specifies range of consoles to be captured by the MDA.
   2389 
   2390 	mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
   2391 			Amount of memory to be used when the kernel is not able
   2392 			to see the whole system memory or for test.
   2393 			[X86] Work as limiting max address. Use together
   2394 			with memmap= to avoid physical address space collisions.
   2395 			Without memmap= PCI devices could be placed at addresses
   2396 			belonging to unused RAM.
   2397 
   2398 	mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
   2399 			memory.
   2400 
   2401 	memchunk=nn[KMG]
   2402 			[KNL,SH] Allow user to override the default size for
   2403 			per-device physically contiguous DMA buffers.
   2404 
   2405 	memhp_default_state=online/offline
   2406 			[KNL] Set the initial state for the memory hotplug
   2407 			onlining policy. If not specified, the default value is
   2408 			set according to the
   2409 			CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
   2410 			option.
   2411 			See Documentation/memory-hotplug.txt.
   2412 
   2413 	memmap=exactmap	[KNL,X86] Enable setting of an exact
   2414 			E820 memory map, as specified by the user.
   2415 			Such memmap=exactmap lines can be constructed based on
   2416 			BIOS output or other requirements. See the memmap=nn@ss
   2417 			option description.
   2418 
   2419 	memmap=nn[KMG]@ss[KMG]
   2420 			[KNL] Force usage of a specific region of memory.
   2421 			Region of memory to be used is from ss to ss+nn.
   2422 			If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG],
   2423 			which limits max address to nn[KMG].
   2424 			Multiple different regions can be specified,
   2425 			comma delimited.
   2426 			Example:
   2427 				memmap=100M@2G,100M#3G,1G!1024G
   2428 
   2429 	memmap=nn[KMG]#ss[KMG]
   2430 			[KNL,ACPI] Mark specific memory as ACPI data.
   2431 			Region of memory to be marked is from ss to ss+nn.
   2432 
   2433 	memmap=nn[KMG]$ss[KMG]
   2434 			[KNL,ACPI] Mark specific memory as reserved.
   2435 			Region of memory to be reserved is from ss to ss+nn.
   2436 			Example: Exclude memory from 0x18690000-0x1869ffff
   2437 			         memmap=64K$0x18690000
   2438 			         or
   2439 			         memmap=0x10000$0x18690000
   2440 			Some bootloaders may need an escape character before '$',
   2441 			like Grub2, otherwise '$' and the following number
   2442 			will be eaten.
   2443 
   2444 	memmap=nn[KMG]!ss[KMG]
   2445 			[KNL,X86] Mark specific memory as protected.
   2446 			Region of memory to be used, from ss to ss+nn.
   2447 			The memory region may be marked as e820 type 12 (0xc)
   2448 			and is NVDIMM or ADR memory.
   2449 
   2450 	memmap=<size>%<offset>-<oldtype>+<newtype>
   2451 			[KNL,ACPI] Convert memory within the specified region
   2452 			from <oldtype> to <newtype>. If "-<oldtype>" is left
   2453 			out, the whole region will be marked as <newtype>,
   2454 			even if previously unavailable. If "+<newtype>" is left
   2455 			out, matching memory will be removed. Types are
   2456 			specified as e820 types, e.g., 1 = RAM, 2 = reserved,
   2457 			3 = ACPI, 12 = PRAM.
   2458 
   2459 	memory_corruption_check=0/1 [X86]
   2460 			Some BIOSes seem to corrupt the first 64k of
   2461 			memory when doing things like suspend/resume.
   2462 			Setting this option will scan the memory
   2463 			looking for corruption.  Enabling this will
   2464 			both detect corruption and prevent the kernel
   2465 			from using the memory being corrupted.
   2466 			However, its intended as a diagnostic tool; if
   2467 			repeatable BIOS-originated corruption always
   2468 			affects the same memory, you can use memmap=
   2469 			to prevent the kernel from using that memory.
   2470 
   2471 	memory_corruption_check_size=size [X86]
   2472 			By default it checks for corruption in the low
   2473 			64k, making this memory unavailable for normal
   2474 			use.  Use this parameter to scan for
   2475 			corruption in more or less memory.
   2476 
   2477 	memory_corruption_check_period=seconds [X86]
   2478 			By default it checks for corruption every 60
   2479 			seconds.  Use this parameter to check at some
   2480 			other rate.  0 disables periodic checking.
   2481 
   2482 	memtest=	[KNL,X86,ARM,PPC] Enable memtest
   2483 			Format: <integer>
   2484 			default : 0 <disable>
   2485 			Specifies the number of memtest passes to be
   2486 			performed. Each pass selects another test
   2487 			pattern from a given set of patterns. Memtest
   2488 			fills the memory with this pattern, validates
   2489 			memory contents and reserves bad memory
   2490 			regions that are detected.
   2491 
   2492 	mem_encrypt=	[X86-64] AMD Secure Memory Encryption (SME) control
   2493 			Valid arguments: on, off
   2494 			Default (depends on kernel configuration option):
   2495 			  on  (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y)
   2496 			  off (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n)
   2497 			mem_encrypt=on:		Activate SME
   2498 			mem_encrypt=off:	Do not activate SME
   2499 
   2500 			Refer to Documentation/x86/amd-memory-encryption.txt
   2501 			for details on when memory encryption can be activated.
   2502 
   2503 	mem_sleep_default=	[SUSPEND] Default system suspend mode:
   2504 			s2idle  - Suspend-To-Idle
   2505 			shallow - Power-On Suspend or equivalent (if supported)
   2506 			deep    - Suspend-To-RAM or equivalent (if supported)
   2507 			See Documentation/admin-guide/pm/sleep-states.rst.
   2508 
   2509 	meye.*=		[HW] Set MotionEye Camera parameters
   2510 			See Documentation/media/v4l-drivers/meye.rst.
   2511 
   2512 	mfgpt_irq=	[IA-32] Specify the IRQ to use for the
   2513 			Multi-Function General Purpose Timers on AMD Geode
   2514 			platforms.
   2515 
   2516 	mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
   2517 			the BIOS has incorrectly applied a workaround. TinyBIOS
   2518 			version 0.98 is known to be affected, 0.99 fixes the
   2519 			problem by letting the user disable the workaround.
   2520 
   2521 	mga=		[HW,DRM]
   2522 
   2523 	min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this
   2524 			physical address is ignored.
   2525 
   2526 	mini2440=	[ARM,HW,KNL]
   2527 			Format:[0..2][b][c][t]
   2528 			Default: "0tb"
   2529 			MINI2440 configuration specification:
   2530 			0 - The attached screen is the 3.5" TFT
   2531 			1 - The attached screen is the 7" TFT
   2532 			2 - The VGA Shield is attached (1024x768)
   2533 			Leaving out the screen size parameter will not load
   2534 			the TFT driver, and the framebuffer will be left
   2535 			unconfigured.
   2536 			b - Enable backlight. The TFT backlight pin will be
   2537 			linked to the kernel VESA blanking code and a GPIO
   2538 			LED. This parameter is not necessary when using the
   2539 			VGA shield.
   2540 			c - Enable the s3c camera interface.
   2541 			t - Reserved for enabling touchscreen support. The
   2542 			touchscreen support is not enabled in the mainstream
   2543 			kernel as of 2.6.30, a preliminary port can be found
   2544 			in the "bleeding edge" mini2440 support kernel at
   2545 			http://repo.or.cz/w/linux-2.6/mini2440.git
   2546 
   2547 	mminit_loglevel=
   2548 			[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
   2549 			parameter allows control of the logging verbosity for
   2550 			the additional memory initialisation checks. A value
   2551 			of 0 disables mminit logging and a level of 4 will
   2552 			log everything. Information is printed at KERN_DEBUG
   2553 			so loglevel=8 may also need to be specified.
   2554 
   2555 	module.sig_enforce
   2556 			[KNL] When CONFIG_MODULE_SIG is set, this means that
   2557 			modules without (valid) signatures will fail to load.
   2558 			Note that if CONFIG_MODULE_SIG_FORCE is set, that
   2559 			is always true, so this option does nothing.
   2560 
   2561 	module_blacklist=  [KNL] Do not load a comma-separated list of
   2562 			modules.  Useful for debugging problem modules.
   2563 
   2564 	mousedev.tap_time=
   2565 			[MOUSE] Maximum time between finger touching and
   2566 			leaving touchpad surface for touch to be considered
   2567 			a tap and be reported as a left button click (for
   2568 			touchpads working in absolute mode only).
   2569 			Format: <msecs>
   2570 	mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
   2571 			reporting absolute coordinates, such as tablets
   2572 	mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
   2573 			reporting absolute coordinates, such as tablets
   2574 
   2575 	movablecore=	[KNL,X86,IA-64,PPC]
   2576 			Format: nn[KMGTPE] | nn%
   2577 			This parameter is the complement to kernelcore=, it
   2578 			specifies the amount of memory used for migratable
   2579 			allocations.  If both kernelcore and movablecore is
   2580 			specified, then kernelcore will be at *least* the
   2581 			specified value but may be more.  If movablecore on its
   2582 			own is specified, the administrator must be careful
   2583 			that the amount of memory usable for all allocations
   2584 			is not too small.
   2585 
   2586 	movable_node	[KNL] Boot-time switch to make hotplugable memory
   2587 			NUMA nodes to be movable. This means that the memory
   2588 			of such nodes will be usable only for movable
   2589 			allocations which rules out almost all kernel
   2590 			allocations. Use with caution!
   2591 
   2592 	MTD_Partition=	[MTD]
   2593 			Format: <name>,<region-number>,<size>,<offset>
   2594 
   2595 	MTD_Region=	[MTD] Format:
   2596 			<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
   2597 
   2598 	mtdparts=	[MTD]
   2599 			See drivers/mtd/cmdlinepart.c.
   2600 
   2601 	multitce=off	[PPC]  This parameter disables the use of the pSeries
   2602 			firmware feature for updating multiple TCE entries
   2603 			at a time.
   2604 
   2605 	onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
   2606 
   2607 			Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
   2608 
   2609 			boundary - index of last SLC block on Flex-OneNAND.
   2610 				   The remaining blocks are configured as MLC blocks.
   2611 			lock	 - Configure if Flex-OneNAND boundary should be locked.
   2612 				   Once locked, the boundary cannot be changed.
   2613 				   1 indicates lock status, 0 indicates unlock status.
   2614 
   2615 	mtdset=		[ARM]
   2616 			ARM/S3C2412 JIVE boot control
   2617 
   2618 			See arch/arm/mach-s3c2412/mach-jive.c
   2619 
   2620 	mtouchusb.raw_coordinates=
   2621 			[HW] Make the MicroTouch USB driver use raw coordinates
   2622 			('y', default) or cooked coordinates ('n')
   2623 
   2624 	mtrr_chunk_size=nn[KMG] [X86]
   2625 			used for mtrr cleanup. It is largest continuous chunk
   2626 			that could hold holes aka. UC entries.
   2627 
   2628 	mtrr_gran_size=nn[KMG] [X86]
   2629 			Used for mtrr cleanup. It is granularity of mtrr block.
   2630 			Default is 1.
   2631 			Large value could prevent small alignment from
   2632 			using up MTRRs.
   2633 
   2634 	mtrr_spare_reg_nr=n [X86]
   2635 			Format: <integer>
   2636 			Range: 0,7 : spare reg number
   2637 			Default : 1
   2638 			Used for mtrr cleanup. It is spare mtrr entries number.
   2639 			Set to 2 or more if your graphical card needs more.
   2640 
   2641 	n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card
   2642 
   2643 	netdev=		[NET] Network devices parameters
   2644 			Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
   2645 			Note that mem_start is often overloaded to mean
   2646 			something different and driver-specific.
   2647 			This usage is only documented in each driver source
   2648 			file if at all.
   2649 
   2650 	nf_conntrack.acct=
   2651 			[NETFILTER] Enable connection tracking flow accounting
   2652 			0 to disable accounting
   2653 			1 to enable accounting
   2654 			Default value is 0.
   2655 
   2656 	nfsaddrs=	[NFS] Deprecated.  Use ip= instead.
   2657 			See Documentation/filesystems/nfs/nfsroot.txt.
   2658 
   2659 	nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
   2660 			See Documentation/filesystems/nfs/nfsroot.txt.
   2661 
   2662 	nfsrootdebug	[NFS] enable nfsroot debugging messages.
   2663 			See Documentation/filesystems/nfs/nfsroot.txt.
   2664 
   2665 	nfs.callback_nr_threads=
   2666 			[NFSv4] set the total number of threads that the
   2667 			NFS client will assign to service NFSv4 callback
   2668 			requests.
   2669 
   2670 	nfs.callback_tcpport=
   2671 			[NFS] set the TCP port on which the NFSv4 callback
   2672 			channel should listen.
   2673 
   2674 	nfs.cache_getent=
   2675 			[NFS] sets the pathname to the program which is used
   2676 			to update the NFS client cache entries.
   2677 
   2678 	nfs.cache_getent_timeout=
   2679 			[NFS] sets the timeout after which an attempt to
   2680 			update a cache entry is deemed to have failed.
   2681 
   2682 	nfs.idmap_cache_timeout=
   2683 			[NFS] set the maximum lifetime for idmapper cache
   2684 			entries.
   2685 
   2686 	nfs.enable_ino64=
   2687 			[NFS] enable 64-bit inode numbers.
   2688 			If zero, the NFS client will fake up a 32-bit inode
   2689 			number for the readdir() and stat() syscalls instead
   2690 			of returning the full 64-bit number.
   2691 			The default is to return 64-bit inode numbers.
   2692 
   2693 	nfs.max_session_cb_slots=
   2694 			[NFSv4.1] Sets the maximum number of session
   2695 			slots the client will assign to the callback
   2696 			channel. This determines the maximum number of
   2697 			callbacks the client will process in parallel for
   2698 			a particular server.
   2699 
   2700 	nfs.max_session_slots=
   2701 			[NFSv4.1] Sets the maximum number of session slots
   2702 			the client will attempt to negotiate with the server.
   2703 			This limits the number of simultaneous RPC requests
   2704 			that the client can send to the NFSv4.1 server.
   2705 			Note that there is little point in setting this
   2706 			value higher than the max_tcp_slot_table_limit.
   2707 
   2708 	nfs.nfs4_disable_idmapping=
   2709 			[NFSv4] When set to the default of '1', this option
   2710 			ensures that both the RPC level authentication
   2711 			scheme and the NFS level operations agree to use
   2712 			numeric uids/gids if the mount is using the
   2713 			'sec=sys' security flavour. In effect it is
   2714 			disabling idmapping, which can make migration from
   2715 			legacy NFSv2/v3 systems to NFSv4 easier.
   2716 			Servers that do not support this mode of operation
   2717 			will be autodetected by the client, and it will fall
   2718 			back to using the idmapper.
   2719 			To turn off this behaviour, set the value to '0'.
   2720 	nfs.nfs4_unique_id=
   2721 			[NFS4] Specify an additional fixed unique ident-
   2722 			ification string that NFSv4 clients can insert into
   2723 			their nfs_client_id4 string.  This is typically a
   2724 			UUID that is generated at system install time.
   2725 
   2726 	nfs.send_implementation_id =
   2727 			[NFSv4.1] Send client implementation identification
   2728 			information in exchange_id requests.
   2729 			If zero, no implementation identification information
   2730 			will be sent.
   2731 			The default is to send the implementation identification
   2732 			information.
   2733 
   2734 	nfs.recover_lost_locks =
   2735 			[NFSv4] Attempt to recover locks that were lost due
   2736 			to a lease timeout on the server. Please note that
   2737 			doing this risks data corruption, since there are
   2738 			no guarantees that the file will remain unchanged
   2739 			after the locks are lost.
   2740 			If you want to enable the kernel legacy behaviour of
   2741 			attempting to recover these locks, then set this
   2742 			parameter to '1'.
   2743 			The default parameter value of '0' causes the kernel
   2744 			not to attempt recovery of lost locks.
   2745 
   2746 	nfs4.layoutstats_timer =
   2747 			[NFSv4.2] Change the rate at which the kernel sends
   2748 			layoutstats to the pNFS metadata server.
   2749 
   2750 			Setting this to value to 0 causes the kernel to use
   2751 			whatever value is the default set by the layout
   2752 			driver. A non-zero value sets the minimum interval
   2753 			in seconds between layoutstats transmissions.
   2754 
   2755 	nfsd.nfs4_disable_idmapping=
   2756 			[NFSv4] When set to the default of '1', the NFSv4
   2757 			server will return only numeric uids and gids to
   2758 			clients using auth_sys, and will accept numeric uids
   2759 			and gids from such clients.  This is intended to ease
   2760 			migration from NFSv2/v3.
   2761 
   2762 	nmi_debug=	[KNL,SH] Specify one or more actions to take
   2763 			when a NMI is triggered.
   2764 			Format: [state][,regs][,debounce][,die]
   2765 
   2766 	nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels
   2767 			Format: [panic,][nopanic,][num]
   2768 			Valid num: 0 or 1
   2769 			0 - turn hardlockup detector in nmi_watchdog off
   2770 			1 - turn hardlockup detector in nmi_watchdog on
   2771 			When panic is specified, panic when an NMI watchdog
   2772 			timeout occurs (or 'nopanic' to override the opposite
   2773 			default). To disable both hard and soft lockup detectors,
   2774 			please see 'nowatchdog'.
   2775 			This is useful when you use a panic=... timeout and
   2776 			need the box quickly up again.
   2777 
   2778 			These settings can be accessed at runtime via
   2779 			the nmi_watchdog and hardlockup_panic sysctls.
   2780 
   2781 	netpoll.carrier_timeout=
   2782 			[NET] Specifies amount of time (in seconds) that
   2783 			netpoll should wait for a carrier. By default netpoll
   2784 			waits 4 seconds.
   2785 
   2786 	no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
   2787 			emulation library even if a 387 maths coprocessor
   2788 			is present.
   2789 
   2790 	no5lvl		[X86-64] Disable 5-level paging mode. Forces
   2791 			kernel to use 4-level paging instead.
   2792 
   2793 	no_console_suspend
   2794 			[HW] Never suspend the console
   2795 			Disable suspending of consoles during suspend and
   2796 			hibernate operations.  Once disabled, debugging
   2797 			messages can reach various consoles while the rest
   2798 			of the system is being put to sleep (ie, while
   2799 			debugging driver suspend/resume hooks).  This may
   2800 			not work reliably with all consoles, but is known
   2801 			to work with serial and VGA consoles.
   2802 			To facilitate more flexible debugging, we also add
   2803 			console_suspend, a printk module parameter to control
   2804 			it. Users could use console_suspend (usually
   2805 			/sys/module/printk/parameters/console_suspend) to
   2806 			turn on/off it dynamically.
   2807 
   2808 	noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
   2809 			caches in the slab allocator.  Saves per-node memory,
   2810 			but will impact performance.
   2811 
   2812 	noalign		[KNL,ARM]
   2813 
   2814 	noaltinstr	[S390] Disables alternative instructions patching
   2815 			(CPU alternatives feature).
   2816 
   2817 	noapic		[SMP,APIC] Tells the kernel to not make use of any
   2818 			IOAPICs that may be present in the system.
   2819 
   2820 	noautogroup	Disable scheduler automatic task group creation.
   2821 
   2822 	nobats		[PPC] Do not use BATs for mapping kernel lowmem
   2823 			on "Classic" PPC cores.
   2824 
   2825 	nocache		[ARM]
   2826 
   2827 	noclflush	[BUGS=X86] Don't use the CLFLUSH instruction
   2828 
   2829 	nodelayacct	[KNL] Disable per-task delay accounting
   2830 
   2831 	nodsp		[SH] Disable hardware DSP at boot time.
   2832 
   2833 	noefi		Disable EFI runtime services support.
   2834 
   2835 	noexec		[IA-64]
   2836 
   2837 	noexec		[X86]
   2838 			On X86-32 available only on PAE configured kernels.
   2839 			noexec=on: enable non-executable mappings (default)
   2840 			noexec=off: disable non-executable mappings
   2841 
   2842 	nosmap		[X86]
   2843 			Disable SMAP (Supervisor Mode Access Prevention)
   2844 			even if it is supported by processor.
   2845 
   2846 	nosmep		[X86]
   2847 			Disable SMEP (Supervisor Mode Execution Prevention)
   2848 			even if it is supported by processor.
   2849 
   2850 	noexec32	[X86-64]
   2851 			This affects only 32-bit executables.
   2852 			noexec32=on: enable non-executable mappings (default)
   2853 				read doesn't imply executable mappings
   2854 			noexec32=off: disable non-executable mappings
   2855 				read implies executable mappings
   2856 
   2857 	nofpu		[MIPS,SH] Disable hardware FPU at boot time.
   2858 
   2859 	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
   2860 			register save and restore. The kernel will only save
   2861 			legacy floating-point registers on task switch.
   2862 
   2863 	nohugeiomap	[KNL,x86] Disable kernel huge I/O mappings.
   2864 
   2865 	nosmt		[KNL,S390] Disable symmetric multithreading (SMT).
   2866 			Equivalent to smt=1.
   2867 
   2868 			[KNL,x86] Disable symmetric multithreading (SMT).
   2869 			nosmt=force: Force disable SMT, cannot be undone
   2870 				     via the sysfs control file.
   2871 
   2872 	nospectre_v1	[PPC] Disable mitigations for Spectre Variant 1 (bounds
   2873 			check bypass). With this option data leaks are possible
   2874 			in the system.
   2875 
   2876 	nospectre_v2	[X86,PPC_FSL_BOOK3E] Disable all mitigations for the Spectre variant 2
   2877 			(indirect branch prediction) vulnerability. System may
   2878 			allow data leaks with this option, which is equivalent
   2879 			to spectre_v2=off.
   2880 
   2881 	nospec_store_bypass_disable
   2882 			[HW] Disable all mitigations for the Speculative Store Bypass vulnerability
   2883 
   2884 	noxsave		[BUGS=X86] Disables x86 extended register state save
   2885 			and restore using xsave. The kernel will fallback to
   2886 			enabling legacy floating-point and sse state.
   2887 
   2888 	noxsaveopt	[X86] Disables xsaveopt used in saving x86 extended
   2889 			register states. The kernel will fall back to use
   2890 			xsave to save the states. By using this parameter,
   2891 			performance of saving the states is degraded because
   2892 			xsave doesn't support modified optimization while
   2893 			xsaveopt supports it on xsaveopt enabled systems.
   2894 
   2895 	noxsaves	[X86] Disables xsaves and xrstors used in saving and
   2896 			restoring x86 extended register state in compacted
   2897 			form of xsave area. The kernel will fall back to use
   2898 			xsaveopt and xrstor to save and restore the states
   2899 			in standard form of xsave area. By using this
   2900 			parameter, xsave area per process might occupy more
   2901 			memory on xsaves enabled systems.
   2902 
   2903 	nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
   2904 			wfi(ARM) instruction doesn't work correctly and not to
   2905 			use it. This is also useful when using JTAG debugger.
   2906 
   2907 	no_file_caps	Tells the kernel not to honor file capabilities.  The
   2908 			only way then for a file to be executed with privilege
   2909 			is to be setuid root or executed by root.
   2910 
   2911 	nohalt		[IA-64] Tells the kernel not to use the power saving
   2912 			function PAL_HALT_LIGHT when idle. This increases
   2913 			power-consumption. On the positive side, it reduces
   2914 			interrupt wake-up latency, which may improve performance
   2915 			in certain environments such as networked servers or
   2916 			real-time systems.
   2917 
   2918 	nohibernate	[HIBERNATION] Disable hibernation and resume.
   2919 
   2920 	nohz=		[KNL] Boottime enable/disable dynamic ticks
   2921 			Valid arguments: on, off
   2922 			Default: on
   2923 
   2924 	nohz_full=	[KNL,BOOT,SMP,ISOL]
   2925 			The argument is a cpu list, as described above.
   2926 			In kernels built with CONFIG_NO_HZ_FULL=y, set
   2927 			the specified list of CPUs whose tick will be stopped
   2928 			whenever possible. The boot CPU will be forced outside
   2929 			the range to maintain the timekeeping.  Any CPUs
   2930 			in this list will have their RCU callbacks offloaded,
   2931 			just as if they had also been called out in the
   2932 			rcu_nocbs= boot parameter.
   2933 
   2934 	noiotrap	[SH] Disables trapped I/O port accesses.
   2935 
   2936 	noirqdebug	[X86-32] Disables the code which attempts to detect and
   2937 			disable unhandled interrupt sources.
   2938 
   2939 	no_timer_check	[X86,APIC] Disables the code which tests for
   2940 			broken timer IRQ sources.
   2941 
   2942 	noisapnp	[ISAPNP] Disables ISA PnP code.
   2943 
   2944 	noinitrd	[RAM] Tells the kernel not to load any configured
   2945 			initial RAM disk.
   2946 
   2947 	nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt
   2948 			remapping.
   2949 			[Deprecated - use intremap=off]
   2950 
   2951 	nointroute	[IA-64]
   2952 
   2953 	noinvpcid	[X86] Disable the INVPCID cpu feature.
   2954 
   2955 	nojitter	[IA-64] Disables jitter checking for ITC timers.
   2956 
   2957 	no-kvmclock	[X86,KVM] Disable paravirtualized KVM clock driver
   2958 
   2959 	no-kvmapf	[X86,KVM] Disable paravirtualized asynchronous page
   2960 			fault handling.
   2961 
   2962 	no-vmw-sched-clock
   2963 			[X86,PV_OPS] Disable paravirtualized VMware scheduler
   2964 			clock and use the default one.
   2965 
   2966 	no-steal-acc	[X86,KVM] Disable paravirtualized steal time accounting.
   2967 			steal time is computed, but won't influence scheduler
   2968 			behaviour
   2969 
   2970 	nolapic		[X86-32,APIC] Do not enable or use the local APIC.
   2971 
   2972 	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
   2973 
   2974 	noltlbs		[PPC] Do not use large page/tlb entries for kernel
   2975 			lowmem mapping on PPC40x and PPC8xx
   2976 
   2977 	nomca		[IA-64] Disable machine check abort handling
   2978 
   2979 	nomce		[X86-32] Disable Machine Check Exception
   2980 
   2981 	nomfgpt		[X86-32] Disable Multi-Function General Purpose
   2982 			Timer usage (for AMD Geode machines).
   2983 
   2984 	nonmi_ipi	[X86] Disable using NMI IPIs during panic/reboot to
   2985 			shutdown the other cpus.  Instead use the REBOOT_VECTOR
   2986 			irq.
   2987 
   2988 	nomodule	Disable module load
   2989 
   2990 	nopat		[X86] Disable PAT (page attribute table extension of
   2991 			pagetables) support.
   2992 
   2993 	nopcid		[X86-64] Disable the PCID cpu feature.
   2994 
   2995 	norandmaps	Don't use address space randomization.  Equivalent to
   2996 			echo 0 > /proc/sys/kernel/randomize_va_space
   2997 
   2998 	noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
   2999 			with UP alternatives
   3000 
   3001 	nordrand	[X86] Disable kernel use of the RDRAND and
   3002 			RDSEED instructions even if they are supported
   3003 			by the processor.  RDRAND and RDSEED are still
   3004 			available to user space applications.
   3005 
   3006 	noresume	[SWSUSP] Disables resume and restores original swap
   3007 			space.
   3008 
   3009 	no-scroll	[VGA] Disables scrollback.
   3010 			This is required for the Braillex ib80-piezo Braille
   3011 			reader made by F.H. Papenmeier (Germany).
   3012 
   3013 	nosbagart	[IA-64]
   3014 
   3015 	nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
   3016 
   3017 	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
   3018 			and disable the IO APIC.  legacy for "maxcpus=0".
   3019 
   3020 	nosoftlockup	[KNL] Disable the soft-lockup detector.
   3021 
   3022 	nosync		[HW,M68K] Disables sync negotiation for all devices.
   3023 
   3024 	nowatchdog	[KNL] Disable both lockup detectors, i.e.
   3025 			soft-lockup and NMI watchdog (hard-lockup).
   3026 
   3027 	nowb		[ARM]
   3028 
   3029 	nox2apic	[X86-64,APIC] Do not enable x2APIC mode.
   3030 
   3031 	cpu0_hotplug	[X86] Turn on CPU0 hotplug feature when
   3032 			CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
   3033 			Some features depend on CPU0. Known dependencies are:
   3034 			1. Resume from suspend/hibernate depends on CPU0.
   3035 			Suspend/hibernate will fail if CPU0 is offline and you
   3036 			need to online CPU0 before suspend/hibernate.
   3037 			2. PIC interrupts also depend on CPU0. CPU0 can't be
   3038 			removed if a PIC interrupt is detected.
   3039 			It's said poweroff/reboot may depend on CPU0 on some
   3040 			machines although I haven't seen such issues so far
   3041 			after CPU0 is offline on a few tested machines.
   3042 			If the dependencies are under your control, you can
   3043 			turn on cpu0_hotplug.
   3044 
   3045 	nps_mtm_hs_ctr=	[KNL,ARC]
   3046 			This parameter sets the maximum duration, in
   3047 			cycles, each HW thread of the CTOP can run
   3048 			without interruptions, before HW switches it.
   3049 			The actual maximum duration is 16 times this
   3050 			parameter's value.
   3051 			Format: integer between 1 and 255
   3052 			Default: 255
   3053 
   3054 	nptcg=		[IA-64] Override max number of concurrent global TLB
   3055 			purges which is reported from either PAL_VM_SUMMARY or
   3056 			SAL PALO.
   3057 
   3058 	nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
   3059 			could support.  nr_cpus=n : n >= 1 limits the kernel to
   3060 			support 'n' processors. It could be larger than the
   3061 			number of already plugged CPU during bootup, later in
   3062 			runtime you can physically add extra cpu until it reaches
   3063 			n. So during boot up some boot time memory for per-cpu
   3064 			variables need be pre-allocated for later physical cpu
   3065 			hot plugging.
   3066 
   3067 	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
   3068 
   3069 	numa_balancing=	[KNL,X86] Enable or disable automatic NUMA balancing.
   3070 			Allowed values are enable and disable
   3071 
   3072 	numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
   3073 			'node', 'default' can be specified
   3074 			This can be set from sysctl after boot.
   3075 			See Documentation/sysctl/vm.txt for details.
   3076 
   3077 	ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
   3078 			See Documentation/debugging-via-ohci1394.txt for more
   3079 			info.
   3080 
   3081 	olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
   3082 			Rather than timing out after 20 ms if an EC
   3083 			command is not properly ACKed, override the length
   3084 			of the timeout.  We have interrupts disabled while
   3085 			waiting for the ACK, so if this is set too high
   3086 			interrupts *may* be lost!
   3087 
   3088 	omap_mux=	[OMAP] Override bootloader pin multiplexing.
   3089 			Format: <mux_mode0.mode_name=value>...
   3090 			For example, to override I2C bus2:
   3091 			omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
   3092 
   3093 	oprofile.timer=	[HW]
   3094 			Use timer interrupt instead of performance counters
   3095 
   3096 	oprofile.cpu_type=	Force an oprofile cpu type
   3097 			This might be useful if you have an older oprofile
   3098 			userland or if you want common events.
   3099 			Format: { arch_perfmon }
   3100 			arch_perfmon: [X86] Force use of architectural
   3101 				perfmon on Intel CPUs instead of the
   3102 				CPU specific event set.
   3103 			timer: [X86] Force use of architectural NMI
   3104 				timer mode (see also oprofile.timer
   3105 				for generic hr timer mode)
   3106 
   3107 	oops=panic	Always panic on oopses. Default is to just kill the
   3108 			process, but there is a small probability of
   3109 			deadlocking the machine.
   3110 			This will also cause panics on machine check exceptions.
   3111 			Useful together with panic=30 to trigger a reboot.
   3112 
   3113 	page_owner=	[KNL] Boot-time page_owner enabling option.
   3114 			Storage of the information about who allocated
   3115 			each page is disabled in default. With this switch,
   3116 			we can turn it on.
   3117 			on: enable the feature
   3118 
   3119 	page_poison=	[KNL] Boot-time parameter changing the state of
   3120 			poisoning on the buddy allocator, available with
   3121 			CONFIG_PAGE_POISONING=y.
   3122 			off: turn off poisoning (default)
   3123 			on: turn on poisoning
   3124 
   3125 	panic=		[KNL] Kernel behaviour on panic: delay <timeout>
   3126 			timeout > 0: seconds before rebooting
   3127 			timeout = 0: wait forever
   3128 			timeout < 0: reboot immediately
   3129 			Format: <timeout>
   3130 
   3131 	panic_print=	Bitmask for printing system info when panic happens.
   3132 			User can chose combination of the following bits:
   3133 			bit 0: print all tasks info
   3134 			bit 1: print system memory info
   3135 			bit 2: print timer info
   3136 			bit 3: print locks info if CONFIG_LOCKDEP is on
   3137 			bit 4: print ftrace buffer
   3138 
   3139 	panic_on_warn	panic() instead of WARN().  Useful to cause kdump
   3140 			on a WARN().
   3141 
   3142 	crash_kexec_post_notifiers
   3143 			Run kdump after running panic-notifiers and dumping
   3144 			kmsg. This only for the users who doubt kdump always
   3145 			succeeds in any situation.
   3146 			Note that this also increases risks of kdump failure,
   3147 			because some panic notifiers can make the crashed
   3148 			kernel more unstable.
   3149 
   3150 	parkbd.port=	[HW] Parallel port number the keyboard adapter is
   3151 			connected to, default is 0.
   3152 			Format: <parport#>
   3153 	parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
   3154 			0 for XT, 1 for AT (default is AT).
   3155 			Format: <mode>
   3156 
   3157 	parport=	[HW,PPT] Specify parallel ports. 0 disables.
   3158 			Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
   3159 			Use 'auto' to force the driver to use any
   3160 			IRQ/DMA settings detected (the default is to
   3161 			ignore detected IRQ/DMA settings because of
   3162 			possible conflicts). You can specify the base
   3163 			address, IRQ, and DMA settings; IRQ and DMA
   3164 			should be numbers, or 'auto' (for using detected
   3165 			settings on that particular port), or 'nofifo'
   3166 			(to avoid using a FIFO even if it is detected).
   3167 			Parallel ports are assigned in the order they
   3168 			are specified on the command line, starting
   3169 			with parport0.
   3170 
   3171 	parport_init_mode=	[HW,PPT]
   3172 			Configure VIA parallel port to operate in
   3173 			a specific mode. This is necessary on Pegasos
   3174 			computer where firmware has no options for setting
   3175 			up parallel port mode and sets it to spp.
   3176 			Currently this function knows 686a and 8231 chips.
   3177 			Format: [spp|ps2|epp|ecp|ecpepp]
   3178 
   3179 	pause_on_oops=
   3180 			Halt all CPUs after the first oops has been printed for
   3181 			the specified number of seconds.  This is to be used if
   3182 			your oopses keep scrolling off the screen.
   3183 
   3184 	pcbit=		[HW,ISDN]
   3185 
   3186 	pcd.		[PARIDE]
   3187 			See header of drivers/block/paride/pcd.c.
   3188 			See also Documentation/blockdev/paride.txt.
   3189 
   3190 	pci=option[,option...]	[PCI] various PCI subsystem options.
   3191 
   3192 				Some options herein operate on a specific device
   3193 				or a set of devices (<pci_dev>). These are
   3194 				specified in one of the following formats:
   3195 
   3196 				[<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]*
   3197 				pci:<vendor>:<device>[:<subvendor>:<subdevice>]
   3198 
   3199 				Note: the first format specifies a PCI
   3200 				bus/device/function address which may change
   3201 				if new hardware is inserted, if motherboard
   3202 				firmware changes, or due to changes caused
   3203 				by other kernel parameters. If the
   3204 				domain is left unspecified, it is
   3205 				taken to be zero. Optionally, a path
   3206 				to a device through multiple device/function
   3207 				addresses can be specified after the base
   3208 				address (this is more robust against
   3209 				renumbering issues).  The second format
   3210 				selects devices using IDs from the
   3211 				configuration space which may match multiple
   3212 				devices in the system.
   3213 
   3214 		earlydump	dump PCI config space before the kernel
   3215 				changes anything
   3216 		off		[X86] don't probe for the PCI bus
   3217 		bios		[X86-32] force use of PCI BIOS, don't access
   3218 				the hardware directly. Use this if your machine
   3219 				has a non-standard PCI host bridge.
   3220 		nobios		[X86-32] disallow use of PCI BIOS, only direct
   3221 				hardware access methods are allowed. Use this
   3222 				if you experience crashes upon bootup and you
   3223 				suspect they are caused by the BIOS.
   3224 		conf1		[X86] Force use of PCI Configuration Access
   3225 				Mechanism 1 (config address in IO port 0xCF8,
   3226 				data in IO port 0xCFC, both 32-bit).
   3227 		conf2		[X86] Force use of PCI Configuration Access
   3228 				Mechanism 2 (IO port 0xCF8 is an 8-bit port for
   3229 				the function, IO port 0xCFA, also 8-bit, sets
   3230 				bus number. The config space is then accessed
   3231 				through ports 0xC000-0xCFFF).
   3232 				See http://wiki.osdev.org/PCI for more info
   3233 				on the configuration access mechanisms.
   3234 		noaer		[PCIE] If the PCIEAER kernel config parameter is
   3235 				enabled, this kernel boot option can be used to
   3236 				disable the use of PCIE advanced error reporting.
   3237 		nodomains	[PCI] Disable support for multiple PCI
   3238 				root domains (aka PCI segments, in ACPI-speak).
   3239 		nommconf	[X86] Disable use of MMCONFIG for PCI
   3240 				Configuration
   3241 		check_enable_amd_mmconf [X86] check for and enable
   3242 				properly configured MMIO access to PCI
   3243 				config space on AMD family 10h CPU
   3244 		nomsi		[MSI] If the PCI_MSI kernel config parameter is
   3245 				enabled, this kernel boot option can be used to
   3246 				disable the use of MSI interrupts system-wide.
   3247 		noioapicquirk	[APIC] Disable all boot interrupt quirks.
   3248 				Safety option to keep boot IRQs enabled. This
   3249 				should never be necessary.
   3250 		ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
   3251 				primary IO-APIC for bridges that cannot disable
   3252 				boot IRQs. This fixes a source of spurious IRQs
   3253 				when the system masks IRQs.
   3254 		noioapicreroute	[APIC] Disable workaround that uses the
   3255 				boot IRQ equivalent of an IRQ that connects to
   3256 				a chipset where boot IRQs cannot be disabled.
   3257 				The opposite of ioapicreroute.
   3258 		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
   3259 				routing table. These calls are known to be buggy
   3260 				on several machines and they hang the machine
   3261 				when used, but on other computers it's the only
   3262 				way to get the interrupt routing table. Try
   3263 				this option if the kernel is unable to allocate
   3264 				IRQs or discover secondary PCI buses on your
   3265 				motherboard.
   3266 		rom		[X86] Assign address space to expansion ROMs.
   3267 				Use with caution as certain devices share
   3268 				address decoders between ROMs and other
   3269 				resources.
   3270 		norom		[X86] Do not assign address space to
   3271 				expansion ROMs that do not already have
   3272 				BIOS assigned address ranges.
   3273 		nobar		[X86] Do not assign address space to the
   3274 				BARs that weren't assigned by the BIOS.
   3275 		irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
   3276 				assigned automatically to PCI devices. You can
   3277 				make the kernel exclude IRQs of your ISA cards
   3278 				this way.
   3279 		pirqaddr=0xAAAAA	[X86] Specify the physical address
   3280 				of the PIRQ table (normally generated
   3281 				by the BIOS) if it is outside the
   3282 				F0000h-100000h range.
   3283 		lastbus=N	[X86] Scan all buses thru bus #N. Can be
   3284 				useful if the kernel is unable to find your
   3285 				secondary buses and you want to tell it
   3286 				explicitly which ones they are.
   3287 		assign-busses	[X86] Always assign all PCI bus
   3288 				numbers ourselves, overriding
   3289 				whatever the firmware may have done.
   3290 		usepirqmask	[X86] Honor the possible IRQ mask stored
   3291 				in the BIOS $PIR table. This is needed on
   3292 				some systems with broken BIOSes, notably
   3293 				some HP Pavilion N5400 and Omnibook XE3
   3294 				notebooks. This will have no effect if ACPI
   3295 				IRQ routing is enabled.
   3296 		noacpi		[X86] Do not use ACPI for IRQ routing
   3297 				or for PCI scanning.
   3298 		use_crs		[X86] Use PCI host bridge window information
   3299 				from ACPI.  On BIOSes from 2008 or later, this
   3300 				is enabled by default.  If you need to use this,
   3301 				please report a bug.
   3302 		nocrs		[X86] Ignore PCI host bridge windows from ACPI.
   3303 				If you need to use this, please report a bug.
   3304 		routeirq	Do IRQ routing for all PCI devices.
   3305 				This is normally done in pci_enable_device(),
   3306 				so this option is a temporary workaround
   3307 				for broken drivers that don't call it.
   3308 		skip_isa_align	[X86] do not align io start addr, so can
   3309 				handle more pci cards
   3310 		noearly		[X86] Don't do any early type 1 scanning.
   3311 				This might help on some broken boards which
   3312 				machine check when some devices' config space
   3313 				is read. But various workarounds are disabled
   3314 				and some IOMMU drivers will not work.
   3315 		bfsort		Sort PCI devices into breadth-first order.
   3316 				This sorting is done to get a device
   3317 				order compatible with older (<= 2.4) kernels.
   3318 		nobfsort	Don't sort PCI devices into breadth-first order.
   3319 		pcie_bus_tune_off	Disable PCIe MPS (Max Payload Size)
   3320 				tuning and use the BIOS-configured MPS defaults.
   3321 		pcie_bus_safe	Set every device's MPS to the largest value
   3322 				supported by all devices below the root complex.
   3323 		pcie_bus_perf	Set device MPS to the largest allowable MPS
   3324 				based on its parent bus. Also set MRRS (Max
   3325 				Read Request Size) to the largest supported
   3326 				value (no larger than the MPS that the device
   3327 				or bus can support) for best performance.
   3328 		pcie_bus_peer2peer	Set every device's MPS to 128B, which
   3329 				every device is guaranteed to support. This
   3330 				configuration allows peer-to-peer DMA between
   3331 				any pair of devices, possibly at the cost of
   3332 				reduced performance.  This also guarantees
   3333 				that hot-added devices will work.
   3334 		cbiosize=nn[KMG]	The fixed amount of bus space which is
   3335 				reserved for the CardBus bridge's IO window.
   3336 				The default value is 256 bytes.
   3337 		cbmemsize=nn[KMG]	The fixed amount of bus space which is
   3338 				reserved for the CardBus bridge's memory
   3339 				window. The default value is 64 megabytes.
   3340 		resource_alignment=
   3341 				Format:
   3342 				[<order of align>@]<pci_dev>[; ...]
   3343 				Specifies alignment and device to reassign
   3344 				aligned memory resources. How to
   3345 				specify the device is described above.
   3346 				If <order of align> is not specified,
   3347 				PAGE_SIZE is used as alignment.
   3348 				PCI-PCI bridge can be specified, if resource
   3349 				windows need to be expanded.
   3350 				To specify the alignment for several
   3351 				instances of a device, the PCI vendor,
   3352 				device, subvendor, and subdevice may be
   3353 				specified, e.g., 4096@pci:8086:9c22:103c:198f
   3354 		ecrc=		Enable/disable PCIe ECRC (transaction layer
   3355 				end-to-end CRC checking).
   3356 				bios: Use BIOS/firmware settings. This is the
   3357 				the default.
   3358 				off: Turn ECRC off
   3359 				on: Turn ECRC on.
   3360 		hpiosize=nn[KMG]	The fixed amount of bus space which is
   3361 				reserved for hotplug bridge's IO window.
   3362 				Default size is 256 bytes.
   3363 		hpmemsize=nn[KMG]	The fixed amount of bus space which is
   3364 				reserved for hotplug bridge's memory window.
   3365 				Default size is 2 megabytes.
   3366 		hpbussize=nn	The minimum amount of additional bus numbers
   3367 				reserved for buses below a hotplug bridge.
   3368 				Default is 1.
   3369 		realloc=	Enable/disable reallocating PCI bridge resources
   3370 				if allocations done by BIOS are too small to
   3371 				accommodate resources required by all child
   3372 				devices.
   3373 				off: Turn realloc off
   3374 				on: Turn realloc on
   3375 		realloc		same as realloc=on
   3376 		noari		do not use PCIe ARI.
   3377 		noats		[PCIE, Intel-IOMMU, AMD-IOMMU]
   3378 				do not use PCIe ATS (and IOMMU device IOTLB).
   3379 		pcie_scan_all	Scan all possible PCIe devices.  Otherwise we
   3380 				only look for one device below a PCIe downstream
   3381 				port.
   3382 		big_root_window	Try to add a big 64bit memory window to the PCIe
   3383 				root complex on AMD CPUs. Some GFX hardware
   3384 				can resize a BAR to allow access to all VRAM.
   3385 				Adding the window is slightly risky (it may
   3386 				conflict with unreported devices), so this
   3387 				taints the kernel.
   3388 		disable_acs_redir=<pci_dev>[; ...]
   3389 				Specify one or more PCI devices (in the format
   3390 				specified above) separated by semicolons.
   3391 				Each device specified will have the PCI ACS
   3392 				redirect capabilities forced off which will
   3393 				allow P2P traffic between devices through
   3394 				bridges without forcing it upstream. Note:
   3395 				this removes isolation between devices and
   3396 				may put more devices in an IOMMU group.
   3397 
   3398 	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
   3399 			Management.
   3400 		off	Disable ASPM.
   3401 		force	Enable ASPM even on devices that claim not to support it.
   3402 			WARNING: Forcing ASPM on may cause system lockups.
   3403 
   3404 	pcie_ports=	[PCIE] PCIe port services handling:
   3405 		native	Use native PCIe services (PME, AER, DPC, PCIe hotplug)
   3406 			even if the platform doesn't give the OS permission to
   3407 			use them.  This may cause conflicts if the platform
   3408 			also tries to use these services.
   3409 		compat	Disable native PCIe services (PME, AER, DPC, PCIe
   3410 			hotplug).
   3411 
   3412 	pcie_port_pm=	[PCIE] PCIe port power management handling:
   3413 		off	Disable power management of all PCIe ports
   3414 		force	Forcibly enable power management of all PCIe ports
   3415 
   3416 	pcie_pme=	[PCIE,PM] Native PCIe PME signaling options:
   3417 		nomsi	Do not use MSI for native PCIe PME signaling (this makes
   3418 			all PCIe root ports use INTx for all services).
   3419 
   3420 	pcmv=		[HW,PCMCIA] BadgePAD 4
   3421 
   3422 	pd_ignore_unused
   3423 			[PM]
   3424 			Keep all power-domains already enabled by bootloader on,
   3425 			even if no driver has claimed them. This is useful
   3426 			for debug and development, but should not be
   3427 			needed on a platform with proper driver support.
   3428 
   3429 	pd.		[PARIDE]
   3430 			See Documentation/blockdev/paride.txt.
   3431 
   3432 	pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
   3433 			boot time.
   3434 			Format: { 0 | 1 }
   3435 			See arch/parisc/kernel/pdc_chassis.c
   3436 
   3437 	percpu_alloc=	Select which percpu first chunk allocator to use.
   3438 			Currently supported values are "embed" and "page".
   3439 			Archs may support subset or none of the	selections.
   3440 			See comments in mm/percpu.c for details on each
   3441 			allocator.  This parameter is primarily	for debugging
   3442 			and performance comparison.
   3443 
   3444 	pf.		[PARIDE]
   3445 			See Documentation/blockdev/paride.txt.
   3446 
   3447 	pg.		[PARIDE]
   3448 			See Documentation/blockdev/paride.txt.
   3449 
   3450 	pirq=		[SMP,APIC] Manual mp-table setup
   3451 			See Documentation/x86/i386/IO-APIC.txt.
   3452 
   3453 	plip=		[PPT,NET] Parallel port network link
   3454 			Format: { parport<nr> | timid | 0 }
   3455 			See also Documentation/admin-guide/parport.rst.
   3456 
   3457 	pmtmr=		[X86] Manual setup of pmtmr I/O Port.
   3458 			Override pmtimer IOPort with a hex value.
   3459 			e.g. pmtmr=0x508
   3460 
   3461 	pnp.debug=1	[PNP]
   3462 			Enable PNP debug messages (depends on the
   3463 			CONFIG_PNP_DEBUG_MESSAGES option).  Change at run-time
   3464 			via /sys/module/pnp/parameters/debug.  We always show
   3465 			current resource usage; turning this on also shows
   3466 			possible settings and some assignment information.
   3467 
   3468 	pnpacpi=	[ACPI]
   3469 			{ off }
   3470 
   3471 	pnpbios=	[ISAPNP]
   3472 			{ on | off | curr | res | no-curr | no-res }
   3473 
   3474 	pnp_reserve_irq=
   3475 			[ISAPNP] Exclude IRQs for the autoconfiguration
   3476 
   3477 	pnp_reserve_dma=
   3478 			[ISAPNP] Exclude DMAs for the autoconfiguration
   3479 
   3480 	pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
   3481 			Ranges are in pairs (I/O port base and size).
   3482 
   3483 	pnp_reserve_mem=
   3484 			[ISAPNP] Exclude memory regions for the
   3485 			autoconfiguration.
   3486 			Ranges are in pairs (memory base and size).
   3487 
   3488 	ports=		[IP_VS_FTP] IPVS ftp helper module
   3489 			Default is 21.
   3490 			Up to 8 (IP_VS_APP_MAX_PORTS) ports
   3491 			may be specified.
   3492 			Format: <port>,<port>....
   3493 
   3494 	powersave=off	[PPC] This option disables power saving features.
   3495 			It specifically disables cpuidle and sets the
   3496 			platform machine description specific power_save
   3497 			function to NULL. On Idle the CPU just reduces
   3498 			execution priority.
   3499 
   3500 	ppc_strict_facility_enable
   3501 			[PPC] This option catches any kernel floating point,
   3502 			Altivec, VSX and SPE outside of regions specifically
   3503 			allowed (eg kernel_enable_fpu()/kernel_disable_fpu()).
   3504 			There is some performance impact when enabling this.
   3505 
   3506 	ppc_tm=		[PPC]
   3507 			Format: {"off"}
   3508 			Disable Hardware Transactional Memory
   3509 
   3510 	print-fatal-signals=
   3511 			[KNL] debug: print fatal signals
   3512 
   3513 			If enabled, warn about various signal handling
   3514 			related application anomalies: too many signals,
   3515 			too many POSIX.1 timers, fatal signals causing a
   3516 			coredump - etc.
   3517 
   3518 			If you hit the warning due to signal overflow,
   3519 			you might want to try "ulimit -i unlimited".
   3520 
   3521 			default: off.
   3522 
   3523 	printk.always_kmsg_dump=
   3524 			Trigger kmsg_dump for cases other than kernel oops or
   3525 			panics
   3526 			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
   3527 			default: disabled
   3528 
   3529 	printk.devkmsg={on,off,ratelimit}
   3530 			Control writing to /dev/kmsg.
   3531 			on - unlimited logging to /dev/kmsg from userspace
   3532 			off - logging to /dev/kmsg disabled
   3533 			ratelimit - ratelimit the logging
   3534 			Default: ratelimit
   3535 
   3536 	printk.time=	Show timing data prefixed to each printk message line
   3537 			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
   3538 
   3539 	processor.max_cstate=	[HW,ACPI]
   3540 			Limit processor to maximum C-state
   3541 			max_cstate=9 overrides any DMI blacklist limit.
   3542 
   3543 	processor.nocst	[HW,ACPI]
   3544 			Ignore the _CST method to determine C-states,
   3545 			instead using the legacy FADT method
   3546 
   3547 	profile=	[KNL] Enable kernel profiling via /proc/profile
   3548 			Format: [<profiletype>,]<number>
   3549 			Param: <profiletype>: "schedule", "sleep", or "kvm"
   3550 				[defaults to kernel profiling]
   3551 			Param: "schedule" - profile schedule points.
   3552 			Param: "sleep" - profile D-state sleeping (millisecs).
   3553 				Requires CONFIG_SCHEDSTATS
   3554 			Param: "kvm" - profile VM exits.
   3555 			Param: <number> - step/bucket size as a power of 2 for
   3556 				statistical time based profiling.
   3557 
   3558 	prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk
   3559 			before loading.
   3560 			See Documentation/blockdev/ramdisk.txt.
   3561 
   3562 	psi=		[KNL] Enable or disable pressure stall information
   3563 			tracking.
   3564 			Format: <bool>
   3565 
   3566 	psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
   3567 			probe for; one of (bare|imps|exps|lifebook|any).
   3568 	psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
   3569 			per second.
   3570 	psmouse.resetafter=	[HW,MOUSE]
   3571 			Try to reset the device after so many bad packets
   3572 			(0 = never).
   3573 	psmouse.resolution=
   3574 			[HW,MOUSE] Set desired mouse resolution, in dpi.
   3575 	psmouse.smartscroll=
   3576 			[HW,MOUSE] Controls Logitech smartscroll autorepeat.
   3577 			0 = disabled, 1 = enabled (default).
   3578 
   3579 	pstore.backend=	Specify the name of the pstore backend to use
   3580 
   3581 	pt.		[PARIDE]
   3582 			See Documentation/blockdev/paride.txt.
   3583 
   3584 	pti=		[X86_64] Control Page Table Isolation of user and
   3585 			kernel address spaces.  Disabling this feature
   3586 			removes hardening, but improves performance of
   3587 			system calls and interrupts.
   3588 
   3589 			on   - unconditionally enable
   3590 			off  - unconditionally disable
   3591 			auto - kernel detects whether your CPU model is
   3592 			       vulnerable to issues that PTI mitigates
   3593 
   3594 			Not specifying this option is equivalent to pti=auto.
   3595 
   3596 	nopti		[X86_64]
   3597 			Equivalent to pti=off
   3598 
   3599 	pty.legacy_count=
   3600 			[KNL] Number of legacy pty's. Overwrites compiled-in
   3601 			default number.
   3602 
   3603 	quiet		[KNL] Disable most log messages
   3604 
   3605 	r128=		[HW,DRM]
   3606 
   3607 	raid=		[HW,RAID]
   3608 			See Documentation/admin-guide/md.rst.
   3609 
   3610 	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
   3611 			See Documentation/blockdev/ramdisk.txt.
   3612 
   3613 	random.trust_cpu={on,off}
   3614 			[KNL] Enable or disable trusting the use of the
   3615 			CPU's random number generator (if available) to
   3616 			fully seed the kernel's CRNG. Default is controlled
   3617 			by CONFIG_RANDOM_TRUST_CPU.
   3618 
   3619 	ras=option[,option,...]	[KNL] RAS-specific options
   3620 
   3621 		cec_disable	[X86]
   3622 				Disable the Correctable Errors Collector,
   3623 				see CONFIG_RAS_CEC help text.
   3624 
   3625 	rcu_nocbs=	[KNL]
   3626 			The argument is a cpu list, as described above.
   3627 
   3628 			In kernels built with CONFIG_RCU_NOCB_CPU=y, set
   3629 			the specified list of CPUs to be no-callback CPUs.
   3630 			Invocation of these CPUs' RCU callbacks will be
   3631 			offloaded to "rcuox/N" kthreads created for that
   3632 			purpose, where "x" is "p" for RCU-preempt, and
   3633 			"s" for RCU-sched, and "N" is the CPU number.
   3634 			This reduces OS jitter on the offloaded CPUs,
   3635 			which can be useful for HPC and real-time
   3636 			workloads.  It can also improve energy efficiency
   3637 			for asymmetric multiprocessors.
   3638 
   3639 	rcu_nocb_poll	[KNL]
   3640 			Rather than requiring that offloaded CPUs
   3641 			(specified by rcu_nocbs= above) explicitly
   3642 			awaken the corresponding "rcuoN" kthreads,
   3643 			make these kthreads poll for callbacks.
   3644 			This improves the real-time response for the
   3645 			offloaded CPUs by relieving them of the need to
   3646 			wake up the corresponding kthread, but degrades
   3647 			energy efficiency by requiring that the kthreads
   3648 			periodically wake up to do the polling.
   3649 
   3650 	rcutree.blimit=	[KNL]
   3651 			Set maximum number of finished RCU callbacks to
   3652 			process in one batch.
   3653 
   3654 	rcutree.dump_tree=	[KNL]
   3655 			Dump the structure of the rcu_node combining tree
   3656 			out at early boot.  This is used for diagnostic
   3657 			purposes, to verify correct tree setup.
   3658 
   3659 	rcutree.gp_cleanup_delay=	[KNL]
   3660 			Set the number of jiffies to delay each step of
   3661 			RCU grace-period cleanup.
   3662 
   3663 	rcutree.gp_init_delay=	[KNL]
   3664 			Set the number of jiffies to delay each step of
   3665 			RCU grace-period initialization.
   3666 
   3667 	rcutree.gp_preinit_delay=	[KNL]
   3668 			Set the number of jiffies to delay each step of
   3669 			RCU grace-period pre-initialization, that is,
   3670 			the propagation of recent CPU-hotplug changes up
   3671 			the rcu_node combining tree.
   3672 
   3673 	rcutree.rcu_fanout_exact= [KNL]
   3674 			Disable autobalancing of the rcu_node combining
   3675 			tree.  This is used by rcutorture, and might
   3676 			possibly be useful for architectures having high
   3677 			cache-to-cache transfer latencies.
   3678 
   3679 	rcutree.rcu_fanout_leaf= [KNL]
   3680 			Change the number of CPUs assigned to each
   3681 			leaf rcu_node structure.  Useful for very
   3682 			large systems, which will choose the value 64,
   3683 			and for NUMA systems with large remote-access
   3684 			latencies, which will choose a value aligned
   3685 			with the appropriate hardware boundaries.
   3686 
   3687 	rcutree.jiffies_till_first_fqs= [KNL]
   3688 			Set delay from grace-period initialization to
   3689 			first attempt to force quiescent states.
   3690 			Units are jiffies, minimum value is zero,
   3691 			and maximum value is HZ.
   3692 
   3693 	rcutree.jiffies_till_next_fqs= [KNL]
   3694 			Set delay between subsequent attempts to force
   3695 			quiescent states.  Units are jiffies, minimum
   3696 			value is one, and maximum value is HZ.
   3697 
   3698 	rcutree.jiffies_till_sched_qs= [KNL]
   3699 			Set required age in jiffies for a
   3700 			given grace period before RCU starts
   3701 			soliciting quiescent-state help from
   3702 			rcu_note_context_switch() and cond_resched().
   3703 			If not specified, the kernel will calculate
   3704 			a value based on the most recent settings
   3705 			of rcutree.jiffies_till_first_fqs
   3706 			and rcutree.jiffies_till_next_fqs.
   3707 			This calculated value may be viewed in
   3708 			rcutree.jiffies_to_sched_qs.  Any attempt to set
   3709 			rcutree.jiffies_to_sched_qs will be cheerfully
   3710 			overwritten.
   3711 
   3712 	rcutree.kthread_prio= 	 [KNL,BOOT]
   3713 			Set the SCHED_FIFO priority of the RCU per-CPU
   3714 			kthreads (rcuc/N). This value is also used for
   3715 			the priority of the RCU boost threads (rcub/N)
   3716 			and for the RCU grace-period kthreads (rcu_bh,
   3717 			rcu_preempt, and rcu_sched). If RCU_BOOST is
   3718 			set, valid values are 1-99 and the default is 1
   3719 			(the least-favored priority).  Otherwise, when
   3720 			RCU_BOOST is not set, valid values are 0-99 and
   3721 			the default is zero (non-realtime operation).
   3722 
   3723 	rcutree.rcu_nocb_leader_stride= [KNL]
   3724 			Set the number of NOCB kthread groups, which
   3725 			defaults to the square root of the number of
   3726 			CPUs.  Larger numbers reduces the wakeup overhead
   3727 			on the per-CPU grace-period kthreads, but increases
   3728 			that same overhead on each group's leader.
   3729 
   3730 	rcutree.qhimark= [KNL]
   3731 			Set threshold of queued RCU callbacks beyond which
   3732 			batch limiting is disabled.
   3733 
   3734 	rcutree.qlowmark= [KNL]
   3735 			Set threshold of queued RCU callbacks below which
   3736 			batch limiting is re-enabled.
   3737 
   3738 	rcutree.rcu_idle_gp_delay= [KNL]
   3739 			Set wakeup interval for idle CPUs that have
   3740 			RCU callbacks (RCU_FAST_NO_HZ=y).
   3741 
   3742 	rcutree.rcu_idle_lazy_gp_delay= [KNL]
   3743 			Set wakeup interval for idle CPUs that have
   3744 			only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
   3745 			Lazy RCU callbacks are those which RCU can
   3746 			prove do nothing more than free memory.
   3747 
   3748 	rcutree.rcu_kick_kthreads= [KNL]
   3749 			Cause the grace-period kthread to get an extra
   3750 			wake_up() if it sleeps three times longer than
   3751 			it should at force-quiescent-state time.
   3752 			This wake_up() will be accompanied by a
   3753 			WARN_ONCE() splat and an ftrace_dump().
   3754 
   3755 	rcutree.sysrq_rcu= [KNL]
   3756 			Commandeer a sysrq key to dump out Tree RCU's
   3757 			rcu_node tree with an eye towards determining
   3758 			why a new grace period has not yet started.
   3759 
   3760 	rcuperf.gp_async= [KNL]
   3761 			Measure performance of asynchronous
   3762 			grace-period primitives such as call_rcu().
   3763 
   3764 	rcuperf.gp_async_max= [KNL]
   3765 			Specify the maximum number of outstanding
   3766 			callbacks per writer thread.  When a writer
   3767 			thread exceeds this limit, it invokes the
   3768 			corresponding flavor of rcu_barrier() to allow
   3769 			previously posted callbacks to drain.
   3770 
   3771 	rcuperf.gp_exp= [KNL]
   3772 			Measure performance of expedited synchronous
   3773 			grace-period primitives.
   3774 
   3775 	rcuperf.holdoff= [KNL]
   3776 			Set test-start holdoff period.  The purpose of
   3777 			this parameter is to delay the start of the
   3778 			test until boot completes in order to avoid
   3779 			interference.
   3780 
   3781 	rcuperf.nreaders= [KNL]
   3782 			Set number of RCU readers.  The value -1 selects
   3783 			N, where N is the number of CPUs.  A value
   3784 			"n" less than -1 selects N-n+1, where N is again
   3785 			the number of CPUs.  For example, -2 selects N
   3786 			(the number of CPUs), -3 selects N+1, and so on.
   3787 			A value of "n" less than or equal to -N selects
   3788 			a single reader.
   3789 
   3790 	rcuperf.nwriters= [KNL]
   3791 			Set number of RCU writers.  The values operate
   3792 			the same as for rcuperf.nreaders.
   3793 			N, where N is the number of CPUs
   3794 
   3795 	rcuperf.perf_type= [KNL]
   3796 			Specify the RCU implementation to test.
   3797 
   3798 	rcuperf.shutdown= [KNL]
   3799 			Shut the system down after performance tests
   3800 			complete.  This is useful for hands-off automated
   3801 			testing.
   3802 
   3803 	rcuperf.verbose= [KNL]
   3804 			Enable additional printk() statements.
   3805 
   3806 	rcuperf.writer_holdoff= [KNL]
   3807 			Write-side holdoff between grace periods,
   3808 			in microseconds.  The default of zero says
   3809 			no holdoff.
   3810 
   3811 	rcutorture.fqs_duration= [KNL]
   3812 			Set duration of force_quiescent_state bursts
   3813 			in microseconds.
   3814 
   3815 	rcutorture.fqs_holdoff= [KNL]
   3816 			Set holdoff time within force_quiescent_state bursts
   3817 			in microseconds.
   3818 
   3819 	rcutorture.fqs_stutter= [KNL]
   3820 			Set wait time between force_quiescent_state bursts
   3821 			in seconds.
   3822 
   3823 	rcutorture.fwd_progress= [KNL]
   3824 			Enable RCU grace-period forward-progress testing
   3825 			for the types of RCU supporting this notion.
   3826 
   3827 	rcutorture.fwd_progress_div= [KNL]
   3828 			Specify the fraction of a CPU-stall-warning
   3829 			period to do tight-loop forward-progress testing.
   3830 
   3831 	rcutorture.fwd_progress_holdoff= [KNL]
   3832 			Number of seconds to wait between successive
   3833 			forward-progress tests.
   3834 
   3835 	rcutorture.fwd_progress_need_resched= [KNL]
   3836 			Enclose cond_resched() calls within checks for
   3837 			need_resched() during tight-loop forward-progress
   3838 			testing.
   3839 
   3840 	rcutorture.gp_cond= [KNL]
   3841 			Use conditional/asynchronous update-side
   3842 			primitives, if available.
   3843 
   3844 	rcutorture.gp_exp= [KNL]
   3845 			Use expedited update-side primitives, if available.
   3846 
   3847 	rcutorture.gp_normal= [KNL]
   3848 			Use normal (non-expedited) asynchronous
   3849 			update-side primitives, if available.
   3850 
   3851 	rcutorture.gp_sync= [KNL]
   3852 			Use normal (non-expedited) synchronous
   3853 			update-side primitives, if available.  If all
   3854 			of rcutorture.gp_cond=, rcutorture.gp_exp=,
   3855 			rcutorture.gp_normal=, and rcutorture.gp_sync=
   3856 			are zero, rcutorture acts as if is interpreted
   3857 			they are all non-zero.
   3858 
   3859 	rcutorture.n_barrier_cbs= [KNL]
   3860 			Set callbacks/threads for rcu_barrier() testing.
   3861 
   3862 	rcutorture.nfakewriters= [KNL]
   3863 			Set number of concurrent RCU writers.  These just
   3864 			stress RCU, they don't participate in the actual
   3865 			test, hence the "fake".
   3866 
   3867 	rcutorture.nreaders= [KNL]
   3868 			Set number of RCU readers.  The value -1 selects
   3869 			N-1, where N is the number of CPUs.  A value
   3870 			"n" less than -1 selects N-n-2, where N is again
   3871 			the number of CPUs.  For example, -2 selects N
   3872 			(the number of CPUs), -3 selects N+1, and so on.
   3873 
   3874 	rcutorture.object_debug= [KNL]
   3875 			Enable debug-object double-call_rcu() testing.
   3876 
   3877 	rcutorture.onoff_holdoff= [KNL]
   3878 			Set time (s) after boot for CPU-hotplug testing.
   3879 
   3880 	rcutorture.onoff_interval= [KNL]
   3881 			Set time (jiffies) between CPU-hotplug operations,
   3882 			or zero to disable CPU-hotplug testing.
   3883 
   3884 	rcutorture.shuffle_interval= [KNL]
   3885 			Set task-shuffle interval (s).  Shuffling tasks
   3886 			allows some CPUs to go into dyntick-idle mode
   3887 			during the rcutorture test.
   3888 
   3889 	rcutorture.shutdown_secs= [KNL]
   3890 			Set time (s) after boot system shutdown.  This
   3891 			is useful for hands-off automated testing.
   3892 
   3893 	rcutorture.stall_cpu= [KNL]
   3894 			Duration of CPU stall (s) to test RCU CPU stall
   3895 			warnings, zero to disable.
   3896 
   3897 	rcutorture.stall_cpu_holdoff= [KNL]
   3898 			Time to wait (s) after boot before inducing stall.
   3899 
   3900 	rcutorture.stall_cpu_irqsoff= [KNL]
   3901 			Disable interrupts while stalling if set.
   3902 
   3903 	rcutorture.stat_interval= [KNL]
   3904 			Time (s) between statistics printk()s.
   3905 
   3906 	rcutorture.stutter= [KNL]
   3907 			Time (s) to stutter testing, for example, specifying
   3908 			five seconds causes the test to run for five seconds,
   3909 			wait for five seconds, and so on.  This tests RCU's
   3910 			ability to transition abruptly to and from idle.
   3911 
   3912 	rcutorture.test_boost= [KNL]
   3913 			Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
   3914 			"Maybe" means test if the RCU implementation
   3915 			under test support RCU priority boosting.
   3916 
   3917 	rcutorture.test_boost_duration= [KNL]
   3918 			Duration (s) of each individual boost test.
   3919 
   3920 	rcutorture.test_boost_interval= [KNL]
   3921 			Interval (s) between each boost test.
   3922 
   3923 	rcutorture.test_no_idle_hz= [KNL]
   3924 			Test RCU's dyntick-idle handling.  See also the
   3925 			rcutorture.shuffle_interval parameter.
   3926 
   3927 	rcutorture.torture_type= [KNL]
   3928 			Specify the RCU implementation to test.
   3929 
   3930 	rcutorture.verbose= [KNL]
   3931 			Enable additional printk() statements.
   3932 
   3933 	rcupdate.rcu_cpu_stall_suppress= [KNL]
   3934 			Suppress RCU CPU stall warning messages.
   3935 
   3936 	rcupdate.rcu_cpu_stall_timeout= [KNL]
   3937 			Set timeout for RCU CPU stall warning messages.
   3938 
   3939 	rcupdate.rcu_expedited= [KNL]
   3940 			Use expedited grace-period primitives, for
   3941 			example, synchronize_rcu_expedited() instead
   3942 			of synchronize_rcu().  This reduces latency,
   3943 			but can increase CPU utilization, degrade
   3944 			real-time latency, and degrade energy efficiency.
   3945 			No effect on CONFIG_TINY_RCU kernels.
   3946 
   3947 	rcupdate.rcu_normal= [KNL]
   3948 			Use only normal grace-period primitives,
   3949 			for example, synchronize_rcu() instead of
   3950 			synchronize_rcu_expedited().  This improves
   3951 			real-time latency, CPU utilization, and
   3952 			energy efficiency, but can expose users to
   3953 			increased grace-period latency.  This parameter
   3954 			overrides rcupdate.rcu_expedited.  No effect on
   3955 			CONFIG_TINY_RCU kernels.
   3956 
   3957 	rcupdate.rcu_normal_after_boot= [KNL]
   3958 			Once boot has completed (that is, after
   3959 			rcu_end_inkernel_boot() has been invoked), use
   3960 			only normal grace-period primitives.  No effect
   3961 			on CONFIG_TINY_RCU kernels.
   3962 
   3963 	rcupdate.rcu_task_stall_timeout= [KNL]
   3964 			Set timeout in jiffies for RCU task stall warning
   3965 			messages.  Disable with a value less than or equal
   3966 			to zero.
   3967 
   3968 	rcupdate.rcu_self_test= [KNL]
   3969 			Run the RCU early boot self tests
   3970 
   3971 	rdinit=		[KNL]
   3972 			Format: <full_path>
   3973 			Run specified binary instead of /init from the ramdisk,
   3974 			used for early userspace startup. See initrd.
   3975 
   3976 	rdt=		[HW,X86,RDT]
   3977 			Turn on/off individual RDT features. List is:
   3978 			cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
   3979 			mba.
   3980 			E.g. to turn on cmt and turn off mba use:
   3981 				rdt=cmt,!mba
   3982 
   3983 	reboot=		[KNL]
   3984 			Format (x86 or x86_64):
   3985 				[w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
   3986 				[[,]s[mp]#### \
   3987 				[[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
   3988 				[[,]f[orce]
   3989 			Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
   3990 			      reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
   3991 			      reboot_force is either force or not specified,
   3992 			      reboot_cpu is s[mp]#### with #### being the processor
   3993 					to be used for rebooting.
   3994 
   3995 	relax_domain_level=
   3996 			[KNL, SMP] Set scheduler's default relax_domain_level.
   3997 			See Documentation/cgroup-v1/cpusets.txt.
   3998 
   3999 	reserve=	[KNL,BUGS] Force kernel to ignore I/O ports or memory
   4000 			Format: <base1>,<size1>[,<base2>,<size2>,...]
   4001 			Reserve I/O ports or memory so the kernel won't use
   4002 			them.  If <base> is less than 0x10000, the region
   4003 			is assumed to be I/O ports; otherwise it is memory.
   4004 
   4005 	reservetop=	[X86-32]
   4006 			Format: nn[KMG]
   4007 			Reserves a hole at the top of the kernel virtual
   4008 			address space.
   4009 
   4010 	reservelow=	[X86]
   4011 			Format: nn[K]
   4012 			Set the amount of memory to reserve for BIOS at
   4013 			the bottom of the address space.
   4014 
   4015 	reset_devices	[KNL] Force drivers to reset the underlying device
   4016 			during initialization.
   4017 
   4018 	resume=		[SWSUSP]
   4019 			Specify the partition device for software suspend
   4020 			Format:
   4021 			{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
   4022 
   4023 	resume_offset=	[SWSUSP]
   4024 			Specify the offset from the beginning of the partition
   4025 			given by "resume=" at which the swap header is located,
   4026 			in <PAGE_SIZE> units (needed only for swap files).
   4027 			See  Documentation/power/swsusp-and-swap-files.txt
   4028 
   4029 	resumedelay=	[HIBERNATION] Delay (in seconds) to pause before attempting to
   4030 			read the resume files
   4031 
   4032 	resumewait	[HIBERNATION] Wait (indefinitely) for resume device to show up.
   4033 			Useful for devices that are detected asynchronously
   4034 			(e.g. USB and MMC devices).
   4035 
   4036 	hibernate=	[HIBERNATION]
   4037 		noresume	Don't check if there's a hibernation image
   4038 				present during boot.
   4039 		nocompress	Don't compress/decompress hibernation images.
   4040 		no		Disable hibernation and resume.
   4041 		protect_image	Turn on image protection during restoration
   4042 				(that will set all pages holding image data
   4043 				during restoration read-only).
   4044 
   4045 	retain_initrd	[RAM] Keep initrd memory after extraction
   4046 
   4047 	rfkill.default_state=
   4048 		0	"airplane mode".  All wifi, bluetooth, wimax, gps, fm,
   4049 			etc. communication is blocked by default.
   4050 		1	Unblocked.
   4051 
   4052 	rfkill.master_switch_mode=
   4053 		0	The "airplane mode" button does nothing.
   4054 		1	The "airplane mode" button toggles between everything
   4055 			blocked and the previous configuration.
   4056 		2	The "airplane mode" button toggles between everything
   4057 			blocked and everything unblocked.
   4058 
   4059 	rhash_entries=	[KNL,NET]
   4060 			Set number of hash buckets for route cache
   4061 
   4062 	ring3mwait=disable
   4063 			[KNL] Disable ring 3 MONITOR/MWAIT feature on supported
   4064 			CPUs.
   4065 
   4066 	ro		[KNL] Mount root device read-only on boot
   4067 
   4068 	rodata=		[KNL]
   4069 		on	Mark read-only kernel memory as read-only (default).
   4070 		off	Leave read-only kernel memory writable for debugging.
   4071 
   4072 	rockchip.usb_uart
   4073 			Enable the uart passthrough on the designated usb port
   4074 			on Rockchip SoCs. When active, the signals of the
   4075 			debug-uart get routed to the D+ and D- pins of the usb
   4076 			port and the regular usb controller gets disabled.
   4077 
   4078 	root=		[KNL] Root filesystem
   4079 			See name_to_dev_t comment in init/do_mounts.c.
   4080 
   4081 	rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
   4082 			mount the root filesystem
   4083 
   4084 	rootflags=	[KNL] Set root filesystem mount option string
   4085 
   4086 	rootfstype=	[KNL] Set root filesystem type
   4087 
   4088 	rootwait	[KNL] Wait (indefinitely) for root device to show up.
   4089 			Useful for devices that are detected asynchronously
   4090 			(e.g. USB and MMC devices).
   4091 
   4092 	rproc_mem=nn[KMG][@address]
   4093 			[KNL,ARM,CMA] Remoteproc physical memory block.
   4094 			Memory area to be used by remote processor image,
   4095 			managed by CMA.
   4096 
   4097 	rw		[KNL] Mount root device read-write on boot
   4098 
   4099 	S		[KNL] Run init in single mode
   4100 
   4101 	s390_iommu=	[HW,S390]
   4102 			Set s390 IOTLB flushing mode
   4103 		strict
   4104 			With strict flushing every unmap operation will result in
   4105 			an IOTLB flush. Default is lazy flushing before reuse,
   4106 			which is faster.
   4107 
   4108 	sa1100ir	[NET]
   4109 			See drivers/net/irda/sa1100_ir.c.
   4110 
   4111 	sbni=		[NET] Granch SBNI12 leased line adapter
   4112 
   4113 	sched_debug	[KNL] Enables verbose scheduler debug messages.
   4114 
   4115 	schedstats=	[KNL,X86] Enable or disable scheduled statistics.
   4116 			Allowed values are enable and disable. This feature
   4117 			incurs a small amount of overhead in the scheduler
   4118 			but is useful for debugging and performance tuning.
   4119 
   4120 	skew_tick=	[KNL] Offset the periodic timer tick per cpu to mitigate
   4121 			xtime_lock contention on larger systems, and/or RCU lock
   4122 			contention on all systems with CONFIG_MAXSMP set.
   4123 			Format: { "0" | "1" }
   4124 			0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
   4125 			1 -- enable.
   4126 			Note: increases power consumption, thus should only be
   4127 			enabled if running jitter sensitive (HPC/RT) workloads.
   4128 
   4129 	security=	[SECURITY] Choose a legacy "major" security module to
   4130 			enable at boot. This has been deprecated by the
   4131 			"lsm=" parameter.
   4132 
   4133 	selinux=	[SELINUX] Disable or enable SELinux at boot time.
   4134 			Format: { "0" | "1" }
   4135 			See security/selinux/Kconfig help text.
   4136 			0 -- disable.
   4137 			1 -- enable.
   4138 			Default value is set via kernel config option.
   4139 			If enabled at boot time, /selinux/disable can be used
   4140 			later to disable prior to initial policy load.
   4141 
   4142 	apparmor=	[APPARMOR] Disable or enable AppArmor at boot time
   4143 			Format: { "0" | "1" }
   4144 			See security/apparmor/Kconfig help text
   4145 			0 -- disable.
   4146 			1 -- enable.
   4147 			Default value is set via kernel config option.
   4148 
   4149 	serialnumber	[BUGS=X86-32]
   4150 
   4151 	shapers=	[NET]
   4152 			Maximal number of shapers.
   4153 
   4154 	simeth=		[IA-64]
   4155 	simscsi=
   4156 
   4157 	slram=		[HW,MTD]
   4158 
   4159 	slab_nomerge	[MM]
   4160 			Disable merging of slabs with similar size. May be
   4161 			necessary if there is some reason to distinguish
   4162 			allocs to different slabs, especially in hardened
   4163 			environments where the risk of heap overflows and
   4164 			layout control by attackers can usually be
   4165 			frustrated by disabling merging. This will reduce
   4166 			most of the exposure of a heap attack to a single
   4167 			cache (risks via metadata attacks are mostly
   4168 			unchanged). Debug options disable merging on their
   4169 			own.
   4170 			For more information see Documentation/vm/slub.rst.
   4171 
   4172 	slab_max_order=	[MM, SLAB]
   4173 			Determines the maximum allowed order for slabs.
   4174 			A high setting may cause OOMs due to memory
   4175 			fragmentation.  Defaults to 1 for systems with
   4176 			more than 32MB of RAM, 0 otherwise.
   4177 
   4178 	slub_debug[=options[,slabs]]	[MM, SLUB]
   4179 			Enabling slub_debug allows one to determine the
   4180 			culprit if slab objects become corrupted. Enabling
   4181 			slub_debug can create guard zones around objects and
   4182 			may poison objects when not in use. Also tracks the
   4183 			last alloc / free. For more information see
   4184 			Documentation/vm/slub.rst.
   4185 
   4186 	slub_memcg_sysfs=	[MM, SLUB]
   4187 			Determines whether to enable sysfs directories for
   4188 			memory cgroup sub-caches. 1 to enable, 0 to disable.
   4189 			The default is determined by CONFIG_SLUB_MEMCG_SYSFS_ON.
   4190 			Enabling this can lead to a very high number of	debug
   4191 			directories and files being created under
   4192 			/sys/kernel/slub.
   4193 
   4194 	slub_max_order= [MM, SLUB]
   4195 			Determines the maximum allowed order for slabs.
   4196 			A high setting may cause OOMs due to memory
   4197 			fragmentation. For more information see
   4198 			Documentation/vm/slub.rst.
   4199 
   4200 	slub_min_objects=	[MM, SLUB]
   4201 			The minimum number of objects per slab. SLUB will
   4202 			increase the slab order up to slub_max_order to
   4203 			generate a sufficiently large slab able to contain
   4204 			the number of objects indicated. The higher the number
   4205 			of objects the smaller the overhead of tracking slabs
   4206 			and the less frequently locks need to be acquired.
   4207 			For more information see Documentation/vm/slub.rst.
   4208 
   4209 	slub_min_order=	[MM, SLUB]
   4210 			Determines the minimum page order for slabs. Must be
   4211 			lower than slub_max_order.
   4212 			For more information see Documentation/vm/slub.rst.
   4213 
   4214 	slub_nomerge	[MM, SLUB]
   4215 			Same with slab_nomerge. This is supported for legacy.
   4216 			See slab_nomerge for more information.
   4217 
   4218 	smart2=		[HW]
   4219 			Format: <io1>[,<io2>[,...,<io8>]]
   4220 
   4221 	smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
   4222 	smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
   4223 	smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
   4224 	smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
   4225 	smsc-ircc2.ircc_irq=	[HW] IRQ line
   4226 	smsc-ircc2.ircc_dma=	[HW] DMA channel
   4227 	smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
   4228 				0: Toshiba Satellite 1800 (GP data pin select)
   4229 				1: Fast pin select (default)
   4230 				2: ATC IRMode
   4231 
   4232 	smt		[KNL,S390] Set the maximum number of threads (logical
   4233 			CPUs) to use per physical CPU on systems capable of
   4234 			symmetric multithreading (SMT). Will be capped to the
   4235 			actual hardware limit.
   4236 			Format: <integer>
   4237 			Default: -1 (no limit)
   4238 
   4239 	softlockup_panic=
   4240 			[KNL] Should the soft-lockup detector generate panics.
   4241 			Format: <integer>
   4242 
   4243 			A nonzero value instructs the soft-lockup detector
   4244 			to panic the machine when a soft-lockup occurs. This
   4245 			is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC
   4246 			which is the respective build-time switch to that
   4247 			functionality.
   4248 
   4249 	softlockup_all_cpu_backtrace=
   4250 			[KNL] Should the soft-lockup detector generate
   4251 			backtraces on all cpus.
   4252 			Format: <integer>
   4253 
   4254 	sonypi.*=	[HW] Sony Programmable I/O Control Device driver
   4255 			See Documentation/laptops/sonypi.txt
   4256 
   4257 	spectre_v2=	[X86] Control mitigation of Spectre variant 2
   4258 			(indirect branch speculation) vulnerability.
   4259 			The default operation protects the kernel from
   4260 			user space attacks.
   4261 
   4262 			on   - unconditionally enable, implies
   4263 			       spectre_v2_user=on
   4264 			off  - unconditionally disable, implies
   4265 			       spectre_v2_user=off
   4266 			auto - kernel detects whether your CPU model is
   4267 			       vulnerable
   4268 
   4269 			Selecting 'on' will, and 'auto' may, choose a
   4270 			mitigation method at run time according to the
   4271 			CPU, the available microcode, the setting of the
   4272 			CONFIG_RETPOLINE configuration option, and the
   4273 			compiler with which the kernel was built.
   4274 
   4275 			Selecting 'on' will also enable the mitigation
   4276 			against user space to user space task attacks.
   4277 
   4278 			Selecting 'off' will disable both the kernel and
   4279 			the user space protections.
   4280 
   4281 			Specific mitigations can also be selected manually:
   4282 
   4283 			retpoline	  - replace indirect branches
   4284 			retpoline,generic - google's original retpoline
   4285 			retpoline,amd     - AMD-specific minimal thunk
   4286 
   4287 			Not specifying this option is equivalent to
   4288 			spectre_v2=auto.
   4289 
   4290 	spectre_v2_user=
   4291 			[X86] Control mitigation of Spectre variant 2
   4292 		        (indirect branch speculation) vulnerability between
   4293 		        user space tasks
   4294 
   4295 			on	- Unconditionally enable mitigations. Is
   4296 				  enforced by spectre_v2=on
   4297 
   4298 			off     - Unconditionally disable mitigations. Is
   4299 				  enforced by spectre_v2=off
   4300 
   4301 			prctl   - Indirect branch speculation is enabled,
   4302 				  but mitigation can be enabled via prctl
   4303 				  per thread.  The mitigation control state
   4304 				  is inherited on fork.
   4305 
   4306 			prctl,ibpb
   4307 				- Like "prctl" above, but only STIBP is
   4308 				  controlled per thread. IBPB is issued
   4309 				  always when switching between different user
   4310 				  space processes.
   4311 
   4312 			seccomp
   4313 				- Same as "prctl" above, but all seccomp
   4314 				  threads will enable the mitigation unless
   4315 				  they explicitly opt out.
   4316 
   4317 			seccomp,ibpb
   4318 				- Like "seccomp" above, but only STIBP is
   4319 				  controlled per thread. IBPB is issued
   4320 				  always when switching between different
   4321 				  user space processes.
   4322 
   4323 			auto    - Kernel selects the mitigation depending on
   4324 				  the available CPU features and vulnerability.
   4325 
   4326 			Default mitigation:
   4327 			If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl"
   4328 
   4329 			Not specifying this option is equivalent to
   4330 			spectre_v2_user=auto.
   4331 
   4332 	spec_store_bypass_disable=
   4333 			[HW] Control Speculative Store Bypass (SSB) Disable mitigation
   4334 			(Speculative Store Bypass vulnerability)
   4335 
   4336 			Certain CPUs are vulnerable to an exploit against a
   4337 			a common industry wide performance optimization known
   4338 			as "Speculative Store Bypass" in which recent stores
   4339 			to the same memory location may not be observed by
   4340 			later loads during speculative execution. The idea
   4341 			is that such stores are unlikely and that they can
   4342 			be detected prior to instruction retirement at the
   4343 			end of a particular speculation execution window.
   4344 
   4345 			In vulnerable processors, the speculatively forwarded
   4346 			store can be used in a cache side channel attack, for
   4347 			example to read memory to which the attacker does not
   4348 			directly have access (e.g. inside sandboxed code).
   4349 
   4350 			This parameter controls whether the Speculative Store
   4351 			Bypass optimization is used.
   4352 
   4353 			On x86 the options are:
   4354 
   4355 			on      - Unconditionally disable Speculative Store Bypass
   4356 			off     - Unconditionally enable Speculative Store Bypass
   4357 			auto    - Kernel detects whether the CPU model contains an
   4358 				  implementation of Speculative Store Bypass and
   4359 				  picks the most appropriate mitigation. If the
   4360 				  CPU is not vulnerable, "off" is selected. If the
   4361 				  CPU is vulnerable the default mitigation is
   4362 				  architecture and Kconfig dependent. See below.
   4363 			prctl   - Control Speculative Store Bypass per thread
   4364 				  via prctl. Speculative Store Bypass is enabled
   4365 				  for a process by default. The state of the control
   4366 				  is inherited on fork.
   4367 			seccomp - Same as "prctl" above, but all seccomp threads
   4368 				  will disable SSB unless they explicitly opt out.
   4369 
   4370 			Default mitigations:
   4371 			X86:	If CONFIG_SECCOMP=y "seccomp", otherwise "prctl"
   4372 
   4373 			On powerpc the options are:
   4374 
   4375 			on,auto - On Power8 and Power9 insert a store-forwarding
   4376 				  barrier on kernel entry and exit. On Power7
   4377 				  perform a software flush on kernel entry and
   4378 				  exit.
   4379 			off	- No action.
   4380 
   4381 			Not specifying this option is equivalent to
   4382 			spec_store_bypass_disable=auto.
   4383 
   4384 	spia_io_base=	[HW,MTD]
   4385 	spia_fio_base=
   4386 	spia_pedr=
   4387 	spia_peddr=
   4388 
   4389 	srcutree.counter_wrap_check [KNL]
   4390 			Specifies how frequently to check for
   4391 			grace-period sequence counter wrap for the
   4392 			srcu_data structure's ->srcu_gp_seq_needed field.
   4393 			The greater the number of bits set in this kernel
   4394 			parameter, the less frequently counter wrap will
   4395 			be checked for.  Note that the bottom two bits
   4396 			are ignored.
   4397 
   4398 	srcutree.exp_holdoff [KNL]
   4399 			Specifies how many nanoseconds must elapse
   4400 			since the end of the last SRCU grace period for
   4401 			a given srcu_struct until the next normal SRCU
   4402 			grace period will be considered for automatic
   4403 			expediting.  Set to zero to disable automatic
   4404 			expediting.
   4405 
   4406 	ssbd=		[ARM64,HW]
   4407 			Speculative Store Bypass Disable control
   4408 
   4409 			On CPUs that are vulnerable to the Speculative
   4410 			Store Bypass vulnerability and offer a
   4411 			firmware based mitigation, this parameter
   4412 			indicates how the mitigation should be used:
   4413 
   4414 			force-on:  Unconditionally enable mitigation for
   4415 				   for both kernel and userspace
   4416 			force-off: Unconditionally disable mitigation for
   4417 				   for both kernel and userspace
   4418 			kernel:    Always enable mitigation in the
   4419 				   kernel, and offer a prctl interface
   4420 				   to allow userspace to register its
   4421 				   interest in being mitigated too.
   4422 
   4423 	stack_guard_gap=	[MM]
   4424 			override the default stack gap protection. The value
   4425 			is in page units and it defines how many pages prior
   4426 			to (for stacks growing down) resp. after (for stacks
   4427 			growing up) the main stack are reserved for no other
   4428 			mapping. Default value is 256 pages.
   4429 
   4430 	stacktrace	[FTRACE]
   4431 			Enabled the stack tracer on boot up.
   4432 
   4433 	stacktrace_filter=[function-list]
   4434 			[FTRACE] Limit the functions that the stack tracer
   4435 			will trace at boot up. function-list is a comma separated
   4436 			list of functions. This list can be changed at run
   4437 			time by the stack_trace_filter file in the debugfs
   4438 			tracing directory. Note, this enables stack tracing
   4439 			and the stacktrace above is not needed.
   4440 
   4441 	sti=		[PARISC,HW]
   4442 			Format: <num>
   4443 			Set the STI (builtin display/keyboard on the HP-PARISC
   4444 			machines) console (graphic card) which should be used
   4445 			as the initial boot-console.
   4446 			See also comment in drivers/video/console/sticore.c.
   4447 
   4448 	sti_font=	[HW]
   4449 			See comment in drivers/video/console/sticore.c.
   4450 
   4451 	stifb=		[HW]
   4452 			Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
   4453 
   4454 	sunrpc.min_resvport=
   4455 	sunrpc.max_resvport=
   4456 			[NFS,SUNRPC]
   4457 			SunRPC servers often require that client requests
   4458 			originate from a privileged port (i.e. a port in the
   4459 			range 0 < portnr < 1024).
   4460 			An administrator who wishes to reserve some of these
   4461 			ports for other uses may adjust the range that the
   4462 			kernel's sunrpc client considers to be privileged
   4463 			using these two parameters to set the minimum and
   4464 			maximum port values.
   4465 
   4466 	sunrpc.svc_rpc_per_connection_limit=
   4467 			[NFS,SUNRPC]
   4468 			Limit the number of requests that the server will
   4469 			process in parallel from a single connection.
   4470 			The default value is 0 (no limit).
   4471 
   4472 	sunrpc.pool_mode=
   4473 			[NFS]
   4474 			Control how the NFS server code allocates CPUs to
   4475 			service thread pools.  Depending on how many NICs
   4476 			you have and where their interrupts are bound, this
   4477 			option will affect which CPUs will do NFS serving.
   4478 			Note: this parameter cannot be changed while the
   4479 			NFS server is running.
   4480 
   4481 			auto	    the server chooses an appropriate mode
   4482 				    automatically using heuristics
   4483 			global	    a single global pool contains all CPUs
   4484 			percpu	    one pool for each CPU
   4485 			pernode	    one pool for each NUMA node (equivalent
   4486 				    to global on non-NUMA machines)
   4487 
   4488 	sunrpc.tcp_slot_table_entries=
   4489 	sunrpc.udp_slot_table_entries=
   4490 			[NFS,SUNRPC]
   4491 			Sets the upper limit on the number of simultaneous
   4492 			RPC calls that can be sent from the client to a
   4493 			server. Increasing these values may allow you to
   4494 			improve throughput, but will also increase the
   4495 			amount of memory reserved for use by the client.
   4496 
   4497 	suspend.pm_test_delay=
   4498 			[SUSPEND]
   4499 			Sets the number of seconds to remain in a suspend test
   4500 			mode before resuming the system (see
   4501 			/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
   4502 			is set. Default value is 5.
   4503 
   4504 	swapaccount=[0|1]
   4505 			[KNL] Enable accounting of swap in memory resource
   4506 			controller if no parameter or 1 is given or disable
   4507 			it if 0 is given (See Documentation/cgroup-v1/memory.txt)
   4508 
   4509 	swiotlb=	[ARM,IA-64,PPC,MIPS,X86]
   4510 			Format: { <int> | force | noforce }
   4511 			<int> -- Number of I/O TLB slabs
   4512 			force -- force using of bounce buffers even if they
   4513 			         wouldn't be automatically used by the kernel
   4514 			noforce -- Never use bounce buffers (for debugging)
   4515 
   4516 	switches=	[HW,M68k]
   4517 
   4518 	sysfs.deprecated=0|1 [KNL]
   4519 			Enable/disable old style sysfs layout for old udev
   4520 			on older distributions. When this option is enabled
   4521 			very new udev will not work anymore. When this option
   4522 			is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
   4523 			in older udev will not work anymore.
   4524 			Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
   4525 			the kernel configuration.
   4526 
   4527 	sysrq_always_enabled
   4528 			[KNL]
   4529 			Ignore sysrq setting - this boot parameter will
   4530 			neutralize any effect of /proc/sys/kernel/sysrq.
   4531 			Useful for debugging.
   4532 
   4533 	tcpmhash_entries= [KNL,NET]
   4534 			Set the number of tcp_metrics_hash slots.
   4535 			Default value is 8192 or 16384 depending on total
   4536 			ram pages. This is used to specify the TCP metrics
   4537 			cache size. See Documentation/networking/ip-sysctl.txt
   4538 			"tcp_no_metrics_save" section for more details.
   4539 
   4540 	tdfx=		[HW,DRM]
   4541 
   4542 	test_suspend=	[SUSPEND][,N]
   4543 			Specify "mem" (for Suspend-to-RAM) or "standby" (for
   4544 			standby suspend) or "freeze" (for suspend type freeze)
   4545 			as the system sleep state during system startup with
   4546 			the optional capability to repeat N number of times.
   4547 			The system is woken from this state using a
   4548 			wakeup-capable RTC alarm.
   4549 
   4550 	thash_entries=	[KNL,NET]
   4551 			Set number of hash buckets for TCP connection
   4552 
   4553 	thermal.act=	[HW,ACPI]
   4554 			-1: disable all active trip points in all thermal zones
   4555 			<degrees C>: override all lowest active trip points
   4556 
   4557 	thermal.crt=	[HW,ACPI]
   4558 			-1: disable all critical trip points in all thermal zones
   4559 			<degrees C>: override all critical trip points
   4560 
   4561 	thermal.nocrt=	[HW,ACPI]
   4562 			Set to disable actions on ACPI thermal zone
   4563 			critical and hot trip points.
   4564 
   4565 	thermal.off=	[HW,ACPI]
   4566 			1: disable ACPI thermal control
   4567 
   4568 	thermal.psv=	[HW,ACPI]
   4569 			-1: disable all passive trip points
   4570 			<degrees C>: override all passive trip points to this
   4571 			value
   4572 
   4573 	thermal.tzp=	[HW,ACPI]
   4574 			Specify global default ACPI thermal zone polling rate
   4575 			<deci-seconds>: poll all this frequency
   4576 			0: no polling (default)
   4577 
   4578 	threadirqs	[KNL]
   4579 			Force threading of all interrupt handlers except those
   4580 			marked explicitly IRQF_NO_THREAD.
   4581 
   4582 	tmem		[KNL,XEN]
   4583 			Enable the Transcendent memory driver if built-in.
   4584 
   4585 	tmem.cleancache=0|1 [KNL, XEN]
   4586 			Default is on (1). Disable the usage of the cleancache
   4587 			API to send anonymous pages to the hypervisor.
   4588 
   4589 	tmem.frontswap=0|1 [KNL, XEN]
   4590 			Default is on (1). Disable the usage of the frontswap
   4591 			API to send swap pages to the hypervisor. If disabled
   4592 			the selfballooning and selfshrinking are force disabled.
   4593 
   4594 	tmem.selfballooning=0|1 [KNL, XEN]
   4595 			Default is on (1). Disable the driving of swap pages
   4596 			to the hypervisor.
   4597 
   4598 	tmem.selfshrinking=0|1 [KNL, XEN]
   4599 			Default is on (1). Partial swapoff that immediately
   4600 			transfers pages from Xen hypervisor back to the
   4601 			kernel based on different criteria.
   4602 
   4603 	topology=	[S390]
   4604 			Format: {off | on}
   4605 			Specify if the kernel should make use of the cpu
   4606 			topology information if the hardware supports this.
   4607 			The scheduler will make use of this information and
   4608 			e.g. base its process migration decisions on it.
   4609 			Default is on.
   4610 
   4611 	topology_updates= [KNL, PPC, NUMA]
   4612 			Format: {off}
   4613 			Specify if the kernel should ignore (off)
   4614 			topology updates sent by the hypervisor to this
   4615 			LPAR.
   4616 
   4617 	tp720=		[HW,PS2]
   4618 
   4619 	tpm_suspend_pcr=[HW,TPM]
   4620 			Format: integer pcr id
   4621 			Specify that at suspend time, the tpm driver
   4622 			should extend the specified pcr with zeros,
   4623 			as a workaround for some chips which fail to
   4624 			flush the last written pcr on TPM_SaveState.
   4625 			This will guarantee that all the other pcrs
   4626 			are saved.
   4627 
   4628 	trace_buf_size=nn[KMG]
   4629 			[FTRACE] will set tracing buffer size on each cpu.
   4630 
   4631 	trace_event=[event-list]
   4632 			[FTRACE] Set and start specified trace events in order
   4633 			to facilitate early boot debugging. The event-list is a
   4634 			comma separated list of trace events to enable. See
   4635 			also Documentation/trace/events.rst
   4636 
   4637 	trace_options=[option-list]
   4638 			[FTRACE] Enable or disable tracer options at boot.
   4639 			The option-list is a comma delimited list of options
   4640 			that can be enabled or disabled just as if you were
   4641 			to echo the option name into
   4642 
   4643 			    /sys/kernel/debug/tracing/trace_options
   4644 
   4645 			For example, to enable stacktrace option (to dump the
   4646 			stack trace of each event), add to the command line:
   4647 
   4648 			      trace_options=stacktrace
   4649 
   4650 			See also Documentation/trace/ftrace.rst "trace options"
   4651 			section.
   4652 
   4653 	tp_printk[FTRACE]
   4654 			Have the tracepoints sent to printk as well as the
   4655 			tracing ring buffer. This is useful for early boot up
   4656 			where the system hangs or reboots and does not give the
   4657 			option for reading the tracing buffer or performing a
   4658 			ftrace_dump_on_oops.
   4659 
   4660 			To turn off having tracepoints sent to printk,
   4661 			 echo 0 > /proc/sys/kernel/tracepoint_printk
   4662 			Note, echoing 1 into this file without the
   4663 			tracepoint_printk kernel cmdline option has no effect.
   4664 
   4665 			** CAUTION **
   4666 
   4667 			Having tracepoints sent to printk() and activating high
   4668 			frequency tracepoints such as irq or sched, can cause
   4669 			the system to live lock.
   4670 
   4671 	traceoff_on_warning
   4672 			[FTRACE] enable this option to disable tracing when a
   4673 			warning is hit. This turns off "tracing_on". Tracing can
   4674 			be enabled again by echoing '1' into the "tracing_on"
   4675 			file located in /sys/kernel/debug/tracing/
   4676 
   4677 			This option is useful, as it disables the trace before
   4678 			the WARNING dump is called, which prevents the trace to
   4679 			be filled with content caused by the warning output.
   4680 
   4681 			This option can also be set at run time via the sysctl
   4682 			option:  kernel/traceoff_on_warning
   4683 
   4684 	transparent_hugepage=
   4685 			[KNL]
   4686 			Format: [always|madvise|never]
   4687 			Can be used to control the default behavior of the system
   4688 			with respect to transparent hugepages.
   4689 			See Documentation/admin-guide/mm/transhuge.rst
   4690 			for more details.
   4691 
   4692 	tsc=		Disable clocksource stability checks for TSC.
   4693 			Format: <string>
   4694 			[x86] reliable: mark tsc clocksource as reliable, this
   4695 			disables clocksource verification at runtime, as well
   4696 			as the stability checks done at bootup.	Used to enable
   4697 			high-resolution timer mode on older hardware, and in
   4698 			virtualized environment.
   4699 			[x86] noirqtime: Do not use TSC to do irq accounting.
   4700 			Used to run time disable IRQ_TIME_ACCOUNTING on any
   4701 			platforms where RDTSC is slow and this accounting
   4702 			can add overhead.
   4703 			[x86] unstable: mark the TSC clocksource as unstable, this
   4704 			marks the TSC unconditionally unstable at bootup and
   4705 			avoids any further wobbles once the TSC watchdog notices.
   4706 
   4707 	turbografx.map[2|3]=	[HW,JOY]
   4708 			TurboGraFX parallel port interface
   4709 			Format:
   4710 			<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
   4711 			See also Documentation/input/devices/joystick-parport.rst
   4712 
   4713 	udbg-immortal	[PPC] When debugging early kernel crashes that
   4714 			happen after console_init() and before a proper
   4715 			console driver takes over, this boot options might
   4716 			help "seeing" what's going on.
   4717 
   4718 	uhash_entries=	[KNL,NET]
   4719 			Set number of hash buckets for UDP/UDP-Lite connections
   4720 
   4721 	uhci-hcd.ignore_oc=
   4722 			[USB] Ignore overcurrent events (default N).
   4723 			Some badly-designed motherboards generate lots of
   4724 			bogus events, for ports that aren't wired to
   4725 			anything.  Set this parameter to avoid log spamming.
   4726 			Note that genuine overcurrent events won't be
   4727 			reported either.
   4728 
   4729 	unknown_nmi_panic
   4730 			[X86] Cause panic on unknown NMI.
   4731 
   4732 	usbcore.authorized_default=
   4733 			[USB] Default USB device authorization:
   4734 			(default -1 = authorized except for wireless USB,
   4735 			0 = not authorized, 1 = authorized, 2 = authorized
   4736 			if device connected to internal port)
   4737 
   4738 	usbcore.autosuspend=
   4739 			[USB] The autosuspend time delay (in seconds) used
   4740 			for newly-detected USB devices (default 2).  This
   4741 			is the time required before an idle device will be
   4742 			autosuspended.  Devices for which the delay is set
   4743 			to a negative value won't be autosuspended at all.
   4744 
   4745 	usbcore.usbfs_snoop=
   4746 			[USB] Set to log all usbfs traffic (default 0 = off).
   4747 
   4748 	usbcore.usbfs_snoop_max=
   4749 			[USB] Maximum number of bytes to snoop in each URB
   4750 			(default = 65536).
   4751 
   4752 	usbcore.blinkenlights=
   4753 			[USB] Set to cycle leds on hubs (default 0 = off).
   4754 
   4755 	usbcore.old_scheme_first=
   4756 			[USB] Start with the old device initialization
   4757 			scheme,  applies only to low and full-speed devices
   4758 			 (default 0 = off).
   4759 
   4760 	usbcore.usbfs_memory_mb=
   4761 			[USB] Memory limit (in MB) for buffers allocated by
   4762 			usbfs (default = 16, 0 = max = 2047).
   4763 
   4764 	usbcore.use_both_schemes=
   4765 			[USB] Try the other device initialization scheme
   4766 			if the first one fails (default 1 = enabled).
   4767 
   4768 	usbcore.initial_descriptor_timeout=
   4769 			[USB] Specifies timeout for the initial 64-byte
   4770 			USB_REQ_GET_DESCRIPTOR request in milliseconds
   4771 			(default 5000 = 5.0 seconds).
   4772 
   4773 	usbcore.nousb	[USB] Disable the USB subsystem
   4774 
   4775 	usbcore.quirks=
   4776 			[USB] A list of quirk entries to augment the built-in
   4777 			usb core quirk list. List entries are separated by
   4778 			commas. Each entry has the form
   4779 			VendorID:ProductID:Flags. The IDs are 4-digit hex
   4780 			numbers and Flags is a set of letters. Each letter
   4781 			will change the built-in quirk; setting it if it is
   4782 			clear and clearing it if it is set. The letters have
   4783 			the following meanings:
   4784 				a = USB_QUIRK_STRING_FETCH_255 (string
   4785 					descriptors must not be fetched using
   4786 					a 255-byte read);
   4787 				b = USB_QUIRK_RESET_RESUME (device can't resume
   4788 					correctly so reset it instead);
   4789 				c = USB_QUIRK_NO_SET_INTF (device can't handle
   4790 					Set-Interface requests);
   4791 				d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't
   4792 					handle its Configuration or Interface
   4793 					strings);
   4794 				e = USB_QUIRK_RESET (device can't be reset
   4795 					(e.g morph devices), don't use reset);
   4796 				f = USB_QUIRK_HONOR_BNUMINTERFACES (device has
   4797 					more interface descriptions than the
   4798 					bNumInterfaces count, and can't handle
   4799 					talking to these interfaces);
   4800 				g = USB_QUIRK_DELAY_INIT (device needs a pause
   4801 					during initialization, after we read
   4802 					the device descriptor);
   4803 				h = USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL (For
   4804 					high speed and super speed interrupt
   4805 					endpoints, the USB 2.0 and USB 3.0 spec
   4806 					require the interval in microframes (1
   4807 					microframe = 125 microseconds) to be
   4808 					calculated as interval = 2 ^
   4809 					(bInterval-1).
   4810 					Devices with this quirk report their
   4811 					bInterval as the result of this
   4812 					calculation instead of the exponent
   4813 					variable used in the calculation);
   4814 				i = USB_QUIRK_DEVICE_QUALIFIER (device can't
   4815 					handle device_qualifier descriptor
   4816 					requests);
   4817 				j = USB_QUIRK_IGNORE_REMOTE_WAKEUP (device
   4818 					generates spurious wakeup, ignore
   4819 					remote wakeup capability);
   4820 				k = USB_QUIRK_NO_LPM (device can't handle Link
   4821 					Power Management);
   4822 				l = USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL
   4823 					(Device reports its bInterval as linear
   4824 					frames instead of the USB 2.0
   4825 					calculation);
   4826 				m = USB_QUIRK_DISCONNECT_SUSPEND (Device needs
   4827 					to be disconnected before suspend to
   4828 					prevent spurious wakeup);
   4829 				n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a
   4830 					pause after every control message);
   4831 				o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra
   4832 					delay after resetting its port);
   4833 			Example: quirks=0781:5580:bk,0a5c:5834:gij
   4834 
   4835 	usbhid.mousepoll=
   4836 			[USBHID] The interval which mice are to be polled at.
   4837 
   4838 	usbhid.jspoll=
   4839 			[USBHID] The interval which joysticks are to be polled at.
   4840 
   4841 	usbhid.kbpoll=
   4842 			[USBHID] The interval which keyboards are to be polled at.
   4843 
   4844 	usb-storage.delay_use=
   4845 			[UMS] The delay in seconds before a new device is
   4846 			scanned for Logical Units (default 1).
   4847 
   4848 	usb-storage.quirks=
   4849 			[UMS] A list of quirks entries to supplement or
   4850 			override the built-in unusual_devs list.  List
   4851 			entries are separated by commas.  Each entry has
   4852 			the form VID:PID:Flags where VID and PID are Vendor
   4853 			and Product ID values (4-digit hex numbers) and
   4854 			Flags is a set of characters, each corresponding
   4855 			to a common usb-storage quirk flag as follows:
   4856 				a = SANE_SENSE (collect more than 18 bytes
   4857 					of sense data);
   4858 				b = BAD_SENSE (don't collect more than 18
   4859 					bytes of sense data);
   4860 				c = FIX_CAPACITY (decrease the reported
   4861 					device capacity by one sector);
   4862 				d = NO_READ_DISC_INFO (don't use
   4863 					READ_DISC_INFO command);
   4864 				e = NO_READ_CAPACITY_16 (don't use
   4865 					READ_CAPACITY_16 command);
   4866 				f = NO_REPORT_OPCODES (don't use report opcodes
   4867 					command, uas only);
   4868 				g = MAX_SECTORS_240 (don't transfer more than
   4869 					240 sectors at a time, uas only);
   4870 				h = CAPACITY_HEURISTICS (decrease the
   4871 					reported device capacity by one
   4872 					sector if the number is odd);
   4873 				i = IGNORE_DEVICE (don't bind to this
   4874 					device);
   4875 				j = NO_REPORT_LUNS (don't use report luns
   4876 					command, uas only);
   4877 				l = NOT_LOCKABLE (don't try to lock and
   4878 					unlock ejectable media);
   4879 				m = MAX_SECTORS_64 (don't transfer more
   4880 					than 64 sectors = 32 KB at a time);
   4881 				n = INITIAL_READ10 (force a retry of the
   4882 					initial READ(10) command);
   4883 				o = CAPACITY_OK (accept the capacity
   4884 					reported by the device);
   4885 				p = WRITE_CACHE (the device cache is ON
   4886 					by default);
   4887 				r = IGNORE_RESIDUE (the device reports
   4888 					bogus residue values);
   4889 				s = SINGLE_LUN (the device has only one
   4890 					Logical Unit);
   4891 				t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
   4892 					commands, uas only);
   4893 				u = IGNORE_UAS (don't bind to the uas driver);
   4894 				w = NO_WP_DETECT (don't test whether the
   4895 					medium is write-protected).
   4896 				y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE
   4897 					even if the device claims no cache)
   4898 			Example: quirks=0419:aaf5:rl,0421:0433:rc
   4899 
   4900 	user_debug=	[KNL,ARM]
   4901 			Format: <int>
   4902 			See arch/arm/Kconfig.debug help text.
   4903 				 1 - undefined instruction events
   4904 				 2 - system calls
   4905 				 4 - invalid data aborts
   4906 				 8 - SIGSEGV faults
   4907 				16 - SIGBUS faults
   4908 			Example: user_debug=31
   4909 
   4910 	userpte=
   4911 			[X86] Flags controlling user PTE allocations.
   4912 
   4913 				nohigh = do not allocate PTE pages in
   4914 					HIGHMEM regardless of setting
   4915 					of CONFIG_HIGHPTE.
   4916 
   4917 	vdso=		[X86,SH]
   4918 			On X86_32, this is an alias for vdso32=.  Otherwise:
   4919 
   4920 			vdso=1: enable VDSO (the default)
   4921 			vdso=0: disable VDSO mapping
   4922 
   4923 	vdso32=		[X86] Control the 32-bit vDSO
   4924 			vdso32=1: enable 32-bit VDSO
   4925 			vdso32=0 or vdso32=2: disable 32-bit VDSO
   4926 
   4927 			See the help text for CONFIG_COMPAT_VDSO for more
   4928 			details.  If CONFIG_COMPAT_VDSO is set, the default is
   4929 			vdso32=0; otherwise, the default is vdso32=1.
   4930 
   4931 			For compatibility with older kernels, vdso32=2 is an
   4932 			alias for vdso32=0.
   4933 
   4934 			Try vdso32=0 if you encounter an error that says:
   4935 			dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
   4936 
   4937 	vector=		[IA-64,SMP]
   4938 			vector=percpu: enable percpu vector domain
   4939 
   4940 	video=		[FB] Frame buffer configuration
   4941 			See Documentation/fb/modedb.txt.
   4942 
   4943 	video.brightness_switch_enabled= [0,1]
   4944 			If set to 1, on receiving an ACPI notify event
   4945 			generated by hotkey, video driver will adjust brightness
   4946 			level and then send out the event to user space through
   4947 			the allocated input device; If set to 0, video driver
   4948 			will only send out the event without touching backlight
   4949 			brightness level.
   4950 			default: 1
   4951 
   4952 	virtio_mmio.device=
   4953 			[VMMIO] Memory mapped virtio (platform) device.
   4954 
   4955 				<size>@<baseaddr>:<irq>[:<id>]
   4956 			where:
   4957 				<size>     := size (can use standard suffixes
   4958 						like K, M and G)
   4959 				<baseaddr> := physical base address
   4960 				<irq>      := interrupt number (as passed to
   4961 						request_irq())
   4962 				<id>       := (optional) platform device id
   4963 			example:
   4964 				virtio_mmio.device=1K@0x100b0000:48:7
   4965 
   4966 			Can be used multiple times for multiple devices.
   4967 
   4968 	vga=		[BOOT,X86-32] Select a particular video mode
   4969 			See Documentation/x86/boot.txt and
   4970 			Documentation/svga.txt.
   4971 			Use vga=ask for menu.
   4972 			This is actually a boot loader parameter; the value is
   4973 			passed to the kernel using a special protocol.
   4974 
   4975 	vm_debug[=options]	[KNL] Available with CONFIG_DEBUG_VM=y.
   4976 			May slow down system boot speed, especially when
   4977 			enabled on systems with a large amount of memory.
   4978 			All options are enabled by default, and this
   4979 			interface is meant to allow for selectively
   4980 			enabling or disabling specific virtual memory
   4981 			debugging features.
   4982 
   4983 			Available options are:
   4984 			  P	Enable page structure init time poisoning
   4985 			  -	Disable all of the above options
   4986 
   4987 	vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
   4988 			size of <nn>. This can be used to increase the
   4989 			minimum size (128MB on x86). It can also be used to
   4990 			decrease the size and leave more room for directly
   4991 			mapped kernel RAM.
   4992 
   4993 	vmcp_cma=nn[MG]	[KNL,S390]
   4994 			Sets the memory size reserved for contiguous memory
   4995 			allocations for the vmcp device driver.
   4996 
   4997 	vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
   4998 			Format: <command>
   4999 
   5000 	vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
   5001 			Format: <command>
   5002 
   5003 	vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
   5004 			Format: <command>
   5005 
   5006 	vsyscall=	[X86-64]
   5007 			Controls the behavior of vsyscalls (i.e. calls to
   5008 			fixed addresses of 0xffffffffff600x00 from legacy
   5009 			code).  Most statically-linked binaries and older
   5010 			versions of glibc use these calls.  Because these
   5011 			functions are at fixed addresses, they make nice
   5012 			targets for exploits that can control RIP.
   5013 
   5014 			emulate     [default] Vsyscalls turn into traps and are
   5015 			            emulated reasonably safely.
   5016 
   5017 			native      Vsyscalls are native syscall instructions.
   5018 			            This is a little bit faster than trapping
   5019 			            and makes a few dynamic recompilers work
   5020 			            better than they would in emulation mode.
   5021 			            It also makes exploits much easier to write.
   5022 
   5023 			none        Vsyscalls don't work at all.  This makes
   5024 			            them quite hard to use for exploits but
   5025 			            might break your system.
   5026 
   5027 	vt.color=	[VT] Default text color.
   5028 			Format: 0xYX, X = foreground, Y = background.
   5029 			Default: 0x07 = light gray on black.
   5030 
   5031 	vt.cur_default=	[VT] Default cursor shape.
   5032 			Format: 0xCCBBAA, where AA, BB, and CC are the same as
   5033 			the parameters of the <Esc>[?A;B;Cc escape sequence;
   5034 			see VGA-softcursor.txt. Default: 2 = underline.
   5035 
   5036 	vt.default_blu=	[VT]
   5037 			Format: <blue0>,<blue1>,<blue2>,...,<blue15>
   5038 			Change the default blue palette of the console.
   5039 			This is a 16-member array composed of values
   5040 			ranging from 0-255.
   5041 
   5042 	vt.default_grn=	[VT]
   5043 			Format: <green0>,<green1>,<green2>,...,<green15>
   5044 			Change the default green palette of the console.
   5045 			This is a 16-member array composed of values
   5046 			ranging from 0-255.
   5047 
   5048 	vt.default_red=	[VT]
   5049 			Format: <red0>,<red1>,<red2>,...,<red15>
   5050 			Change the default red palette of the console.
   5051 			This is a 16-member array composed of values
   5052 			ranging from 0-255.
   5053 
   5054 	vt.default_utf8=
   5055 			[VT]
   5056 			Format=<0|1>
   5057 			Set system-wide default UTF-8 mode for all tty's.
   5058 			Default is 1, i.e. UTF-8 mode is enabled for all
   5059 			newly opened terminals.
   5060 
   5061 	vt.global_cursor_default=
   5062 			[VT]
   5063 			Format=<-1|0|1>
   5064 			Set system-wide default for whether a cursor
   5065 			is shown on new VTs. Default is -1,
   5066 			i.e. cursors will be created by default unless
   5067 			overridden by individual drivers. 0 will hide
   5068 			cursors, 1 will display them.
   5069 
   5070 	vt.italic=	[VT] Default color for italic text; 0-15.
   5071 			Default: 2 = green.
   5072 
   5073 	vt.underline=	[VT] Default color for underlined text; 0-15.
   5074 			Default: 3 = cyan.
   5075 
   5076 	watchdog timers	[HW,WDT] For information on watchdog timers,
   5077 			see Documentation/watchdog/watchdog-parameters.txt
   5078 			or other driver-specific files in the
   5079 			Documentation/watchdog/ directory.
   5080 
   5081 	watchdog_thresh=
   5082 			[KNL]
   5083 			Set the hard lockup detector stall duration
   5084 			threshold in seconds. The soft lockup detector
   5085 			threshold is set to twice the value. A value of 0
   5086 			disables both lockup detectors. Default is 10
   5087 			seconds.
   5088 
   5089 	workqueue.watchdog_thresh=
   5090 			If CONFIG_WQ_WATCHDOG is configured, workqueue can
   5091 			warn stall conditions and dump internal state to
   5092 			help debugging.  0 disables workqueue stall
   5093 			detection; otherwise, it's the stall threshold
   5094 			duration in seconds.  The default value is 30 and
   5095 			it can be updated at runtime by writing to the
   5096 			corresponding sysfs file.
   5097 
   5098 	workqueue.disable_numa
   5099 			By default, all work items queued to unbound
   5100 			workqueues are affine to the NUMA nodes they're
   5101 			issued on, which results in better behavior in
   5102 			general.  If NUMA affinity needs to be disabled for
   5103 			whatever reason, this option can be used.  Note
   5104 			that this also can be controlled per-workqueue for
   5105 			workqueues visible under /sys/bus/workqueue/.
   5106 
   5107 	workqueue.power_efficient
   5108 			Per-cpu workqueues are generally preferred because
   5109 			they show better performance thanks to cache
   5110 			locality; unfortunately, per-cpu workqueues tend to
   5111 			be more power hungry than unbound workqueues.
   5112 
   5113 			Enabling this makes the per-cpu workqueues which
   5114 			were observed to contribute significantly to power
   5115 			consumption unbound, leading to measurably lower
   5116 			power usage at the cost of small performance
   5117 			overhead.
   5118 
   5119 			The default value of this parameter is determined by
   5120 			the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
   5121 
   5122 	workqueue.debug_force_rr_cpu
   5123 			Workqueue used to implicitly guarantee that work
   5124 			items queued without explicit CPU specified are put
   5125 			on the local CPU.  This guarantee is no longer true
   5126 			and while local CPU is still preferred work items
   5127 			may be put on foreign CPUs.  This debug option
   5128 			forces round-robin CPU selection to flush out
   5129 			usages which depend on the now broken guarantee.
   5130 			When enabled, memory and cache locality will be
   5131 			impacted.
   5132 
   5133 	x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
   5134 			default x2apic cluster mode on platforms
   5135 			supporting x2apic.
   5136 
   5137 	x86_intel_mid_timer= [X86-32,APBT]
   5138 			Choose timer option for x86 Intel MID platform.
   5139 			Two valid options are apbt timer only and lapic timer
   5140 			plus one apbt timer for broadcast timer.
   5141 			x86_intel_mid_timer=apbt_only | lapic_and_apbt
   5142 
   5143 	xen_512gb_limit		[KNL,X86-64,XEN]
   5144 			Restricts the kernel running paravirtualized under Xen
   5145 			to use only up to 512 GB of RAM. The reason to do so is
   5146 			crash analysis tools and Xen tools for doing domain
   5147 			save/restore/migration must be enabled to handle larger
   5148 			domains.
   5149 
   5150 	xen_emul_unplug=		[HW,X86,XEN]
   5151 			Unplug Xen emulated devices
   5152 			Format: [unplug0,][unplug1]
   5153 			ide-disks -- unplug primary master IDE devices
   5154 			aux-ide-disks -- unplug non-primary-master IDE devices
   5155 			nics -- unplug network devices
   5156 			all -- unplug all emulated devices (NICs and IDE disks)
   5157 			unnecessary -- unplugging emulated devices is
   5158 				unnecessary even if the host did not respond to
   5159 				the unplug protocol
   5160 			never -- do not unplug even if version check succeeds
   5161 
   5162 	xen_nopvspin	[X86,XEN]
   5163 			Disables the ticketlock slowpath using Xen PV
   5164 			optimizations.
   5165 
   5166 	xen_nopv	[X86]
   5167 			Disables the PV optimizations forcing the HVM guest to
   5168 			run as generic HVM guest with no PV drivers.
   5169 
   5170 	xen_scrub_pages=	[XEN]
   5171 			Boolean option to control scrubbing pages before giving them back
   5172 			to Xen, for use by other domains. Can be also changed at runtime
   5173 			with /sys/devices/system/xen_memory/xen_memory0/scrub_pages.
   5174 			Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.
   5175 
   5176 	xirc2ps_cs=	[NET,PCMCIA]
   5177 			Format:
   5178 			<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
   5179 
   5180 	xhci-hcd.quirks		[USB,KNL]
   5181 			A hex value specifying bitmask with supplemental xhci
   5182 			host controller quirks. Meaning of each bit can be
   5183 			consulted in header drivers/usb/host/xhci.h.