selftests/powerpc: rfi_flush: disable entry flush if present

[linux-2.6-block.git] / Documentation / admin-guide / kernel-parameters.txt

	acpi=		[HW,ACPI,X86,ARM64]
			Advanced Configuration and Power Interface
			Format: { force | on | off | strict | noirq | rsdt |
				  copy_dsdt }
			force -- enable ACPI if default was off
			on -- enable ACPI but allow fallback to DT [arm64]
			off -- disable ACPI if default was on
			noirq -- do not use ACPI for IRQ routing
			strict -- Be less tolerant of platforms that are not
				strictly ACPI specification compliant.
			rsdt -- prefer RSDT over (default) XSDT
			copy_dsdt -- copy DSDT to memory
			For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force"
			are available

			See also Documentation/power/runtime_pm.rst, pci=noacpi

	acpi_apic_instance=	[ACPI, IOAPIC]
			Format: <int>
			2: use 2nd APIC table, if available
			1,0: use 1st APIC table
			default: 0

	acpi_backlight=	[HW,ACPI]
			{ vendor | video | native | none }
			If set to vendor, prefer vendor-specific driver
			(e.g. thinkpad_acpi, sony_acpi, etc.) instead
			of the ACPI video.ko driver.
			If set to video, use the ACPI video.ko driver.
			If set to native, use the device's native backlight mode.
			If set to none, disable the ACPI backlight interface.

	acpi_force_32bit_fadt_addr
			force FADT to use 32 bit addresses rather than the
			64 bit X_* addresses. Some firmware have broken 64
			bit addresses for force ACPI ignore these and use
			the older legacy 32 bit addresses.

	acpica_no_return_repair [HW, ACPI]
			Disable AML predefined validation mechanism
			This mechanism can repair the evaluation result to make
			the return objects more ACPI specification compliant.
			This option is useful for developers to identify the
			root cause of an AML interpreter issue when the issue
			has something to do with the repair mechanism.

	acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
	acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
			Format: <int>
			CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
			debug output.  Bits in debug_layer correspond to a
			_COMPONENT in an ACPI source file, e.g.,
			    #define _COMPONENT ACPI_PCI_COMPONENT
			Bits in debug_level correspond to a level in
			ACPI_DEBUG_PRINT statements, e.g.,
			    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
			The debug_level mask defaults to "info".  See
			Documentation/firmware-guide/acpi/debug.rst for more information about
			debug layers and levels.

			Enable processor driver info messages:
			    acpi.debug_layer=0x20000000
			Enable PCI/PCI interrupt routing info messages:
			    acpi.debug_layer=0x400000
			Enable AML "Debug" output, i.e., stores to the Debug
			object while interpreting AML:
			    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
			Enable all messages related to ACPI hardware:
			    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff

			Some values produce so much output that the system is
			unusable.  The "log_buf_len" parameter may be useful
			if you need to capture more output.

	acpi_enforce_resources=	[ACPI]
			{ strict | lax | no }
			Check for resource conflicts between native drivers
			and ACPI OperationRegions (SystemIO and SystemMemory
			only). IO ports and memory declared in ACPI might be
			used by the ACPI subsystem in arbitrary AML code and
			can interfere with legacy drivers.
			strict (default): access to resources claimed by ACPI
			is denied; legacy drivers trying to access reserved
			resources will fail to bind to device using them.
			lax: access to resources claimed by ACPI is allowed;
			legacy drivers trying to access reserved resources
			will bind successfully but a warning message is logged.
			no: ACPI OperationRegions are not marked as reserved,
			no further checks are performed.

	acpi_force_table_verification	[HW,ACPI]
			Enable table checksum verification during early stage.
			By default, this is disabled due to x86 early mapping
			size limitation.

	acpi_irq_balance [HW,ACPI]
			ACPI will balance active IRQs
			default in APIC mode

	acpi_irq_nobalance [HW,ACPI]
			ACPI will not move active IRQs (default)
			default in PIC mode

	acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
			Format: <irq>,<irq>...

	acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
			use by PCI
			Format: <irq>,<irq>...

	acpi_mask_gpe=	[HW,ACPI]
			Due to the existence of _Lxx/_Exx, some GPEs triggered
			by unsupported hardware/firmware features can result in
			GPE floodings that cannot be automatically disabled by
			the GPE dispatcher.
			This facility can be used to prevent such uncontrolled
			GPE floodings.
			Format: <byte>

	acpi_no_auto_serialize	[HW,ACPI]
			Disable auto-serialization of AML methods
			AML control methods that contain the opcodes to create
			named objects will be marked as "Serialized" by the
			auto-serialization feature.
			This feature is enabled by default.
			This option allows to turn off the feature.

	acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kdump
			   kernels.

	acpi_no_static_ssdt	[HW,ACPI]
			Disable installation of static SSDTs at early boot time
			By default, SSDTs contained in the RSDT/XSDT will be
			installed automatically and they will appear under
			/sys/firmware/acpi/tables.
			This option turns off this feature.
			Note that specifying this option does not affect
			dynamic table installation which will install SSDT
			tables to /sys/firmware/acpi/tables/dynamic.

	acpi_no_watchdog	[HW,ACPI,WDT]
			Ignore the ACPI-based watchdog interface (WDAT) and let
			a native driver control the watchdog device instead.

	acpi_rsdp=	[ACPI,EFI,KEXEC]
			Pass the RSDP address to the kernel, mostly used
			on machines running EFI runtime service to boot the
			second kernel for kdump.

	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
			Format: To spoof as Windows 98: ="Microsoft Windows"

	acpi_rev_override [ACPI] Override the _REV object to return 5 (instead
			of 2 which is mandated by ACPI 6) as the supported ACPI
			specification revision (when using this switch, it may
			be necessary to carry out a cold reboot _twice_ in a
			row to make it take effect on the platform firmware).

	acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
			acpi_osi="string1"	# add string1
			acpi_osi="!string2"	# remove string2
			acpi_osi=!*		# remove all strings
			acpi_osi=!		# disable all built-in OS vendor
						  strings
			acpi_osi=!!		# enable all built-in OS vendor
						  strings
			acpi_osi=		# disable all strings

			'acpi_osi=!' can be used in combination with single or
			multiple 'acpi_osi="string1"' to support specific OS
			vendor string(s).  Note that such command can only
			affect the default state of the OS vendor strings, thus
			it cannot affect the default state of the feature group
			strings and the current state of the OS vendor strings,
			specifying it multiple times through kernel command line
			is meaningless.  This command is useful when one do not
			care about the state of the feature group strings which
			should be controlled by the OSPM.
			Examples:
			  1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
			     to 'acpi_osi="Windows 2000" acpi_osi=!', they all
			     can make '_OSI("Windows 2000")' TRUE.

			'acpi_osi=' cannot be used in combination with other
			'acpi_osi=' command lines, the _OSI method will not
			exist in the ACPI namespace.  NOTE that such command can
			only affect the _OSI support state, thus specifying it
			multiple times through kernel command line is also
			meaningless.
			Examples:
			  1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
			     FALSE.

			'acpi_osi=!*' can be used in combination with single or
			multiple 'acpi_osi="string1"' to support specific
			string(s).  Note that such command can affect the
			current state of both the OS vendor strings and the
			feature group strings, thus specifying it multiple times
			through kernel command line is meaningful.  But it may
			still not able to affect the final state of a string if
			there are quirks related to this string.  This command
			is useful when one want to control the state of the
			feature group strings to debug BIOS issues related to
			the OSPM features.
			Examples:
			  1. 'acpi_osi="Module Device" acpi_osi=!*' can make
			     '_OSI("Module Device")' FALSE.
			  2. 'acpi_osi=!* acpi_osi="Module Device"' can make
			     '_OSI("Module Device")' TRUE.
			  3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
			     equivalent to
			     'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
			     and
			     'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
			     they all will make '_OSI("Windows 2000")' TRUE.

	acpi_pm_good	[X86]
			Override the pmtimer bug detection: force the kernel
			to assume that this machine's pmtimer latches its value
			and always returns good values.

	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
			Format: { level | edge | high | low }

	acpi_skip_timer_override [HW,ACPI]
			Recognize and ignore IRQ0/pin2 Interrupt Override.
			For broken nForce2 BIOS resulting in XT-PIC timer.

	acpi_sleep=	[HW,ACPI] Sleep options
			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
				  old_ordering, nonvs, sci_force_enable, nobl }
			See Documentation/power/video.rst for information on
			s3_bios and s3_mode.
			s3_beep is for debugging; it makes the PC's speaker beep
			as soon as the kernel's real-mode entry point is called.
			s4_nohwsig prevents ACPI hardware signature from being
			used during resume from hibernation.
			old_ordering causes the ACPI 1.0 ordering of the _PTS
			control method, with respect to putting devices into
			low power states, to be enforced (the ACPI 2.0 ordering
			of _PTS is used by default).
			nonvs prevents the kernel from saving/restoring the
			ACPI NVS memory during suspend/hibernation and resume.
			sci_force_enable causes the kernel to set SCI_EN directly
			on resume from S1/S3 (which is against the ACPI spec,
			but some broken systems don't work without it).
			nobl causes the internal blacklist of systems known to
			behave incorrectly in some ways with respect to system
			suspend and resume to be ignored (use wisely).

	acpi_use_timer_override [HW,ACPI]
			Use timer override. For some broken Nvidia NF5 boards
			that require a timer override, but don't have HPET

	add_efi_memmap	[EFI; X86] Include EFI memory map in
			kernel's map of available physical RAM.

	agp=		[AGP]
			{ off | try_unsupported }
			off: disable AGP support
			try_unsupported: try to drive unsupported chipsets
				(may crash computer or cause data corruption)

	ALSA		[HW,ALSA]
			See Documentation/sound/alsa-configuration.rst

	alignment=	[KNL,ARM]
			Allow the default userspace alignment fault handler
			behaviour to be specified.  Bit 0 enables warnings,
			bit 1 enables fixups, and bit 2 sends a segfault.

	align_va_addr=	[X86-64]
			Align virtual addresses by clearing slice [14:12] when
			allocating a VMA at process creation time. This option
			gives you up to 3% performance improvement on AMD F15h
			machines (where it is enabled by default) for a
			CPU-intensive style benchmark, and it can vary highly in
			a microbenchmark depending on workload and compiler.

			32: only for 32-bit processes
			64: only for 64-bit processes
			on: enable for both 32- and 64-bit processes
			off: disable for both 32- and 64-bit processes

	alloc_snapshot	[FTRACE]
			Allocate the ftrace snapshot buffer on boot up when the
			main buffer is allocated. This is handy if debugging
			and you need to use tracing_snapshot() on boot up, and
			do not want to use tracing_snapshot_alloc() as it needs
			to be done where GFP_KERNEL allocations are allowed.

	amd_iommu=	[HW,X86-64]
			Pass parameters to the AMD IOMMU driver in the system.
			Possible values are:
			fullflush - enable flushing of IO/TLB entries when
				    they are unmapped. Otherwise they are
				    flushed before they will be reused, which
				    is a lot of faster
			off	  - do not initialize any AMD IOMMU found in
				    the system
			force_isolation - Force device isolation for all
					  devices. The IOMMU driver is not
					  allowed anymore to lift isolation
					  requirements as needed. This option
					  does not override iommu=pt

	amd_iommu_dump=	[HW,X86-64]
			Enable AMD IOMMU driver option to dump the ACPI table
			for AMD IOMMU. With this option enabled, AMD IOMMU
			driver will print ACPI tables for AMD IOMMU during
			IOMMU initialization.

	amd_iommu_intr=	[HW,X86-64]
			Specifies one of the following AMD IOMMU interrupt
			remapping modes:
			legacy     - Use legacy interrupt remapping mode.
			vapic      - Use virtual APIC mode, which allows IOMMU
			             to inject interrupts directly into guest.
			             This mode requires kvm-amd.avic=1.
			             (Default when IOMMU HW support is present.)

	amijoy.map=	[HW,JOY] Amiga joystick support
			Map of devices attached to JOY0DAT and JOY1DAT
			Format: <a>,<b>
			See also Documentation/input/joydev/joystick.rst

	analog.map=	[HW,JOY] Analog joystick and gamepad support
			Specifies type or capabilities of an analog joystick
			connected to one of 16 gameports
			Format: <type1>,<type2>,..<type16>

	apc=		[HW,SPARC]
			Power management functions (SPARCstation-4/5 + deriv.)
			Format: noidle
			Disable APC CPU standby support. SPARCstation-Fox does
			not play well with APC CPU idle - disable it if you have
			APC and your system crashes randomly.

	apic=		[APIC,X86] Advanced Programmable Interrupt Controller
			Change the output verbosity while booting
			Format: { quiet (default) | verbose | debug }
			Change the amount of debugging information output
			when initialising the APIC and IO-APIC components.
			For X86-32, this can also be used to specify an APIC
			driver name.
			Format: apic=driver_name
			Examples: apic=bigsmp

	apic_extnmi=	[APIC,X86] External NMI delivery setting
			Format: { bsp (default) | all | none }
			bsp:  External NMI is delivered only to CPU 0
			all:  External NMIs are broadcast to all CPUs as a
			      backup of CPU 0
			none: External NMI is masked for all CPUs. This is
			      useful so that a dump capture kernel won't be
			      shot down by NMI

	autoconf=	[IPV6]
			See Documentation/networking/ipv6.rst.

	show_lapic=	[APIC,X86] Advanced Programmable Interrupt Controller
			Limit apic dumping. The parameter defines the maximal
			number of local apics being dumped. Also it is possible
			to set it to "all" by meaning -- no limit here.
			Format: { 1 (default) | 2 | ... | all }.
			The parameter valid if only apic=debug or
			apic=verbose is specified.
			Example: apic=debug show_lapic=all

	apm=		[APM] Advanced Power Management
			See header of arch/x86/kernel/apm_32.c.

	arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
			Format: <io>,<irq>,<nodeID>

	ataflop=	[HW,M68k]

	atarimouse=	[HW,MOUSE] Atari Mouse

	atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
			EzKey and similar keyboards

	atkbd.reset=	[HW] Reset keyboard during initialization

	atkbd.set=	[HW] Select keyboard code set
			Format: <int> (2 = AT (default), 3 = PS/2)

	atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
			keyboards

	atkbd.softraw=	[HW] Choose between synthetic and real raw mode
			Format: <bool> (0 = real, 1 = synthetic (default))

	atkbd.softrepeat= [HW]
			Use software keyboard repeat

	audit=		[KNL] Enable the audit sub-system
			Format: { "0" | "1" | "off" | "on" }
			0 | off - kernel audit is disabled and can not be
			    enabled until the next reboot
			unset - kernel audit is initialized but disabled and
			    will be fully enabled by the userspace auditd.
			1 | on - kernel audit is initialized and partially
			    enabled, storing at most audit_backlog_limit
			    messages in RAM until it is fully enabled by the
			    userspace auditd.
			Default: unset

	audit_backlog_limit= [KNL] Set the audit queue size limit.
			Format: <int> (must be >=0)
			Default: 64

	bau=		[X86_UV] Enable the BAU on SGI UV.  The default
			behavior is to disable the BAU (i.e. bau=0).
			Format: { "0" | "1" }
			0 - Disable the BAU.
			1 - Enable the BAU.
			unset - Disable the BAU.

	baycom_epp=	[HW,AX25]
			Format: <io>,<mode>

	baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
			Format: <io>,<mode>
			See header of drivers/net/hamradio/baycom_par.c.

	baycom_ser_fdx=	[HW,AX25]
			BayCom Serial Port AX.25 Modem (Full Duplex Mode)
			Format: <io>,<irq>,<mode>[,<baud>]
			See header of drivers/net/hamradio/baycom_ser_fdx.c.

	baycom_ser_hdx=	[HW,AX25]
			BayCom Serial Port AX.25 Modem (Half Duplex Mode)
			Format: <io>,<irq>,<mode>
			See header of drivers/net/hamradio/baycom_ser_hdx.c.

	blkdevparts=	Manual partition parsing of block device(s) for
			embedded devices based on command line input.
			See Documentation/block/cmdline-partition.rst

	boot_delay=	Milliseconds to delay each printk during boot.
			Values larger than 10 seconds (10000) are changed to
			no delay (0).
			Format: integer

	bootconfig	[KNL]
			Extended command line options can be added to an initrd
			and this will cause the kernel to look for it.

			See Documentation/admin-guide/bootconfig.rst

	bert_disable	[ACPI]
			Disable BERT OS support on buggy BIOSes.

	bgrt_disable	[ACPI][X86]
			Disable BGRT to avoid flickering OEM logo.

	bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
	bttv.radio=	Most important insmod options are available as
			kernel args too.
	bttv.pll=	See Documentation/admin-guide/media/bttv.rst
	bttv.tuner=

	bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
			firmware feature for flushing multiple hpte entries
			at a time.

	c101=		[NET] Moxa C101 synchronous serial card

	cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
			Sometimes CPU hardware bugs make them report the cache
			size incorrectly. The kernel will attempt work arounds
			to fix known problems, but for some CPUs it is not
			possible to determine what the correct size should be.
			This option provides an override for these situations.

	carrier_timeout=
			[NET] Specifies amount of time (in seconds) that
			the kernel should wait for a network carrier. By default
			it waits 120 seconds.

	ca_keys=	[KEYS] This parameter identifies a specific key(s) on
			the system trusted keyring to be used for certificate
			trust validation.
			format: { id:<keyid> | builtin }

	cca=		[MIPS] Override the kernel pages' cache coherency
			algorithm.  Accepted values range from 0 to 7
			inclusive. See arch/mips/include/asm/pgtable-bits.h
			for platform specific values (SB1, Loongson3 and
			others).

	ccw_timeout_log	[S390]
			See Documentation/s390/common_io.rst for details.

	cgroup_disable=	[KNL] Disable a particular controller
			Format: {name of the controller(s) to disable}
			The effects of cgroup_disable=foo are:
			- foo isn't auto-mounted if you mount all cgroups in
			  a single hierarchy
			- foo isn't visible as an individually mountable
			  subsystem
			{Currently only "memory" controller deal with this and
			cut the overhead, others just disable the usage. So
			only cgroup_disable=memory is actually worthy}

	cgroup_no_v1=	[KNL] Disable cgroup controllers and named hierarchies in v1
			Format: { { controller | "all" | "named" }
			          [,{ controller | "all" | "named" }...] }
			Like cgroup_disable, but only applies to cgroup v1;
			the blacklisted controllers remain available in cgroup2.
			"all" blacklists all controllers and "named" disables
			named mounts. Specifying both "all" and "named" disables
			all v1 hierarchies.

	cgroup.memory=	[KNL] Pass options to the cgroup memory controller.
			Format: <string>
			nosocket -- Disable socket memory accounting.
			nokmem -- Disable kernel memory accounting.

	checkreqprot	[SELINUX] Set initial checkreqprot flag value.
			Format: { "0" | "1" }
			See security/selinux/Kconfig help text.
			0 -- check protection applied by kernel (includes
				any implied execute protection).
			1 -- check protection requested by application.
			Default value is set via a kernel config option.
			Value can be changed at runtime via
				/sys/fs/selinux/checkreqprot.
			Setting checkreqprot to 1 is deprecated.

	cio_ignore=	[S390]
			See Documentation/s390/common_io.rst for details.
	clk_ignore_unused
			[CLK]
			Prevents the clock framework from automatically gating
			clocks that have not been explicitly enabled by a Linux
			device driver but are enabled in hardware at reset or
			by the bootloader/firmware. Note that this does not
			force such clocks to be always-on nor does it reserve
			those clocks in any way. This parameter is useful for
			debug and development, but should not be needed on a
			platform with proper driver support.  For more
			information, see Documentation/driver-api/clk.rst.

	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
			[Deprecated]
			Forces specified clocksource (if available) to be used
			when calculating gettimeofday(). If specified
			clocksource is not available, it defaults to PIT.
			Format: { pit | tsc | cyclone | pmtmr }

	clocksource=	Override the default clocksource
			Format: <string>
			Override the default clocksource and use the clocksource
			with the name specified.
			Some clocksource names to choose from, depending on
			the platform:
			[all] jiffies (this is the base, fallback clocksource)
			[ACPI] acpi_pm
			[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
				pxa_timer,timer3,32k_counter,timer0_1
			[X86-32] pit,hpet,tsc;
				scx200_hrt on Geode; cyclone on IBM x440
			[MIPS] MIPS
			[PARISC] cr16
			[S390] tod
			[SH] SuperH
			[SPARC64] tick
			[X86-64] hpet,tsc

	clocksource.arm_arch_timer.evtstrm=
			[ARM,ARM64]
			Format: <bool>
			Enable/disable the eventstream feature of the ARM
			architected timer so that code using WFE-based polling
			loops can be debugged more effectively on production
			systems.

	clearcpuid=BITNUM[,BITNUM...] [X86]
			Disable CPUID feature X for the kernel. See
			arch/x86/include/asm/cpufeatures.h for the valid bit
			numbers. Note the Linux specific bits are not necessarily
			stable over kernel options, but the vendor specific
			ones should be.
			Also note that user programs calling CPUID directly
			or using the feature without checking anything
			will still see it. This just prevents it from
			being used by the kernel or shown in /proc/cpuinfo.
			Also note the kernel might malfunction if you disable
			some critical bits.

	cma=nn[MG]@[start[MG][-end[MG]]]
			[KNL,CMA]
			Sets the size of kernel global memory area for
			contiguous memory allocations and optionally the
			placement constraint by the physical address range of
			memory allocations. A value of 0 disables CMA
			altogether. For more information, see
			kernel/dma/contiguous.c

	cma_pernuma=nn[MG]
			[ARM64,KNL]
			Sets the size of kernel per-numa memory area for
			contiguous memory allocations. A value of 0 disables
			per-numa CMA altogether. And If this option is not
			specificed, the default value is 0.
			With per-numa CMA enabled, DMA users on node nid will
			first try to allocate buffer from the pernuma area
			which is located in node nid, if the allocation fails,
			they will fallback to the global default memory area.

	cmo_free_hint=	[PPC] Format: { yes | no }
			Specify whether pages are marked as being inactive
			when they are freed.  This is used in CMO environments
			to determine OS memory pressure for page stealing by
			a hypervisor.
			Default: yes

	coherent_pool=nn[KMG]	[ARM,KNL]
			Sets the size of memory pool for coherent, atomic dma
			allocations, by default set to 256K.

	com20020=	[HW,NET] ARCnet - COM20020 chipset
			Format:
			<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]

	com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
			Format: <io>[,<irq>]

	com90xx=	[HW,NET]
			ARCnet - COM90xx chipset (memory-mapped buffers)
			Format: <io>[,<irq>[,<memstart>]]

	condev=		[HW,S390] console device
	conmode=

	console=	[KNL] Output console device and options.

		tty<n>	Use the virtual console device <n>.

		ttyS<n>[,options]
		ttyUSB0[,options]
			Use the specified serial port.  The options are of
			the form "bbbbpnf", where "bbbb" is the baud rate,
			"p" is parity ("n", "o", or "e"), "n" is number of
			bits, and "f" is flow control ("r" for RTS or
			omit it).  Default is "9600n8".

			See Documentation/admin-guide/serial-console.rst for more
			information.  See
			Documentation/networking/netconsole.rst for an
			alternative.

		uart[8250],io,<addr>[,options]
		uart[8250],mmio,<addr>[,options]
		uart[8250],mmio16,<addr>[,options]
		uart[8250],mmio32,<addr>[,options]
		uart[8250],0x<addr>[,options]
			Start an early, polled-mode console on the 8250/16550
			UART at the specified I/O port or MMIO address,
			switching to the matching ttyS device later.
			MMIO inter-register address stride is either 8-bit
			(mmio), 16-bit (mmio16), or 32-bit (mmio32).
			If none of [io|mmio|mmio16|mmio32], <addr> is assumed
			to be equivalent to 'mmio'. 'options' are specified in
			the same format described for ttyS above; if unspecified,
			the h/w is not re-initialized.

		hvc<n>	Use the hypervisor console device <n>. This is for
			both Xen and PowerPC hypervisors.

		If the device connected to the port is not a TTY but a braille
		device, prepend "brl," before the device type, for instance
			console=brl,ttyS0
		For now, only VisioBraille is supported.

	console_msg_format=
			[KNL] Change console messages format
		default
			By default we print messages on consoles in
			"[time stamp] text\n" format (time stamp may not be
			printed, depending on CONFIG_PRINTK_TIME or
			`printk_time' param).
		syslog
			Switch to syslog format: "<%u>[time stamp] text\n"
			IOW, each message will have a facility and loglevel
			prefix. The format is similar to one used by syslog()
			syscall, or to executing "dmesg -S --raw" or to reading
			from /proc/kmsg.

	consoleblank=	[KNL] The console blank (screen saver) timeout in
			seconds. A value of 0 disables the blank timer.
			Defaults to 0.

	coredump_filter=
			[KNL] Change the default value for
			/proc/<pid>/coredump_filter.
			See also Documentation/filesystems/proc.rst.

	coresight_cpu_debug.enable
			[ARM,ARM64]
			Format: <bool>
			Enable/disable the CPU sampling based debugging.
			0: default value, disable debugging
			1: enable debugging at boot time

	cpuidle.off=1	[CPU_IDLE]
			disable the cpuidle sub-system

	cpuidle.governor=
			[CPU_IDLE] Name of the cpuidle governor to use.

	cpufreq.off=1	[CPU_FREQ]
			disable the cpufreq sub-system

	cpufreq.default_governor=
			[CPU_FREQ] Name of the default cpufreq governor or
			policy to use. This governor must be registered in the
			kernel before the cpufreq driver probes.

	cpu_init_udelay=N
			[X86] Delay for N microsec between assert and de-assert
			of APIC INIT to start processors.  This delay occurs
			on every CPU online, such as boot, and resume from suspend.
			Default: 10000

	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
			Format:
			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

	crashkernel=size[KMG][@offset[KMG]]
			[KNL] Using kexec, Linux can switch to a 'crash kernel'
			upon panic. This parameter reserves the physical
			memory region [offset, offset + size] for that kernel
			image. If '@offset' is omitted, then a suitable offset
			is selected automatically.
			[KNL, X86-64] Select a region under 4G first, and
			fall back to reserve region above 4G when '@offset'
			hasn't been specified.
			See Documentation/admin-guide/kdump/kdump.rst for further details.

	crashkernel=range1:size1[,range2:size2,...][@offset]
			[KNL] Same as above, but depends on the memory
			in the running system. The syntax of range is
			start-[end] where start and end are both
			a memory unit (amount[KMG]). See also
			Documentation/admin-guide/kdump/kdump.rst for an example.

	crashkernel=size[KMG],high
			[KNL, X86-64] range could be above 4G. Allow kernel
			to allocate physical memory region from top, so could
			be above 4G if system have more than 4G ram installed.
			Otherwise memory region will be allocated below 4G, if
			available.
			It will be ignored if crashkernel=X is specified.
	crashkernel=size[KMG],low
			[KNL, X86-64] range under 4G. When crashkernel=X,high
			is passed, kernel could allocate physical memory region
			above 4G, that cause second kernel crash on system
			that require some amount of low memory, e.g. swiotlb
			requires at least 64M+32K low memory, also enough extra
			low memory is needed to make sure DMA buffers for 32-bit
			devices won't run out. Kernel would try to allocate at
			at least 256M below 4G automatically.
			This one let user to specify own low range under 4G
			for second kernel instead.
			0: to disable low allocation.
			It will be ignored when crashkernel=X,high is not used
			or memory reserved is below 4G.

	cryptomgr.notests
			[KNL] Disable crypto self-tests

	cs89x0_dma=	[HW,NET]
			Format: <dma>

	cs89x0_media=	[HW,NET]
			Format: { rj45 | aui | bnc }

	dasd=		[HW,NET]
			See header of drivers/s390/block/dasd_devmap.c.

	db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
			(one device per port)
			Format: <port#>,<type>
			See also Documentation/input/devices/joystick-parport.rst

	ddebug_query=	[KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
			time. See
			Documentation/admin-guide/dynamic-debug-howto.rst for
			details.  Deprecated, see dyndbg.

	debug		[KNL] Enable kernel debugging (events log level).

	debug_boot_weak_hash
			[KNL] Enable printing [hashed] pointers early in the
			boot sequence.  If enabled, we use a weak hash instead
			of siphash to hash pointers.  Use this option if you are
			seeing instances of '(___ptrval___)') and need to see a
			value (hashed pointer) instead. Cryptographically
			insecure, please do not use on production kernels.

	debug_locks_verbose=
			[KNL] verbose self-tests
			Format=<0|1>
			Print debugging info while doing the locking API
			self-tests.
			We default to 0 (no extra messages), setting it to
			1 will print _a lot_ more information - normally
			only useful to kernel developers.

	debug_objects	[KNL] Enable object debugging

	no_debug_objects
			[KNL] Disable object debugging

	debug_guardpage_minorder=
			[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
			parameter allows control of the order of pages that will
			be intentionally kept free (and hence protected) by the
			buddy allocator. Bigger value increase the probability
			of catching random memory corruption, but reduce the
			amount of memory for normal system use. The maximum
			possible value is MAX_ORDER/2.  Setting this parameter
			to 1 or 2 should be enough to identify most random
			memory corruption problems caused by bugs in kernel or
			driver code when a CPU writes to (or reads from) a
			random memory location. Note that there exists a class
			of memory corruptions problems caused by buggy H/W or
			F/W or by drivers badly programing DMA (basically when
			memory is written at bus level and the CPU MMU is
			bypassed) which are not detectable by
			CONFIG_DEBUG_PAGEALLOC, hence this option will not help
			tracking down these problems.

	debug_pagealloc=
			[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this parameter
			enables the feature at boot time. By default, it is
			disabled and the system will work mostly the same as a
			kernel built without CONFIG_DEBUG_PAGEALLOC.
			Note: to get most of debug_pagealloc error reports, it's
			useful to also enable the page_owner functionality.
			on: enable the feature

	debugfs=    	[KNL] This parameter enables what is exposed to userspace
			and debugfs internal clients.
			Format: { on, no-mount, off }
			on: 	All functions are enabled.
			no-mount:
				Filesystem is not registered but kernel clients can
			        access APIs and a crashkernel can be used to read
				its content. There is nothing to mount.
			off: 	Filesystem is not registered and clients
			        get a -EPERM as result when trying to register files
				or directories within debugfs.
				This is equivalent of the runtime functionality if
				debugfs was not enabled in the kernel at all.
			Default value is set in build-time with a kernel configuration.

	debugpat	[X86] Enable PAT debugging

	decnet.addr=	[HW,NET]
			Format: <area>[,<node>]
			See also Documentation/networking/decnet.rst.

	default_hugepagesz=
			[HW] The size of the default HugeTLB page. This is
			the size represented by the legacy /proc/ hugepages
			APIs.  In addition, this is the default hugetlb size
			used for shmget(), mmap() and mounting hugetlbfs
			filesystems.  If not specified, defaults to the
			architecture's default huge page size.  Huge page
			sizes are architecture dependent.  See also
			Documentation/admin-guide/mm/hugetlbpage.rst.
			Format: size[KMG]

	deferred_probe_timeout=
			[KNL] Debugging option to set a timeout in seconds for
			deferred probe to give up waiting on dependencies to
			probe. Only specific dependencies (subsystems or
			drivers) that have opted in will be ignored. A timeout of 0
			will timeout at the end of initcalls. This option will also
			dump out devices still on the deferred probe list after
			retrying.

	dfltcc=		[HW,S390]
			Format: { on | off | def_only | inf_only | always }
			on:       s390 zlib hardware support for compression on
			          level 1 and decompression (default)
			off:      No s390 zlib hardware support
			def_only: s390 zlib hardware support for deflate
			          only (compression on level 1)
			inf_only: s390 zlib hardware support for inflate
			          only (decompression)
			always:   Same as 'on' but ignores the selected compression
			          level always using hardware support (used for debugging)

	dhash_entries=	[KNL]
			Set number of hash buckets for dentry cache.

	disable_1tb_segments [PPC]
			Disables the use of 1TB hash page table segments. This
			causes the kernel to fall back to 256MB segments which
			can be useful when debugging issues that require an SLB
			miss to occur.

	stress_slb	[PPC]
			Limits the number of kernel SLB entries, and flushes
			them frequently to increase the rate of SLB faults
			on kernel addresses.

	disable=	[IPV6]
			See Documentation/networking/ipv6.rst.

	hardened_usercopy=
                        [KNL] Under CONFIG_HARDENED_USERCOPY, whether
                        hardening is enabled for this boot. Hardened
                        usercopy checking is used to protect the kernel
                        from reading or writing beyond known memory
                        allocation boundaries as a proactive defense
                        against bounds-checking flaws in the kernel's
                        copy_to_user()/copy_from_user() interface.
                on      Perform hardened usercopy checks (default).
                off     Disable hardened usercopy checks.

	disable_radix	[PPC]
			Disable RADIX MMU mode on POWER9

	radix_hcall_invalidate=on  [PPC/PSERIES]
			Disable RADIX GTSE feature and use hcall for TLB
			invalidate.

	disable_tlbie	[PPC]
			Disable TLBIE instruction. Currently does not work
			with KVM, with HASH MMU, or with coherent accelerators.

	disable_cpu_apicid= [X86,APIC,SMP]
			Format: <int>
			The number of initial APIC ID for the
			corresponding CPU to be disabled at boot,
			mostly used for the kdump 2nd kernel to
			disable BSP to wake up multiple CPUs without
			causing system reset or hang due to sending
			INIT from AP to BSP.

	perf_v4_pmi=	[X86,INTEL]
			Format: <bool>
			Disable Intel PMU counter freezing feature.
			The feature only exists starting from
			Arch Perfmon v4 (Skylake and newer).

	disable_ddw	[PPC/PSERIES]
			Disable Dynamic DMA Window support. Use this
			to workaround buggy firmware.

	disable_ipv6=	[IPV6]
			See Documentation/networking/ipv6.rst.

	disable_mtrr_cleanup [X86]
			The kernel tries to adjust MTRR layout from continuous
			to discrete, to make X server driver able to add WB
			entry later. This parameter disables that.

	disable_mtrr_trim [X86, Intel and AMD only]
			By default the kernel will trim any uncacheable
			memory out of your available memory pool based on
			MTRR settings.  This parameter disables that behavior,
			possibly causing your machine to run very slowly.

	disable_timer_pin_1 [X86]
			Disable PIN 1 of APIC timer
			Can be useful to work around chipset bugs.

	dis_ucode_ldr	[X86] Disable the microcode loader.

	dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
			this option disables the debugging code at boot.

	dma_debug_entries=<number>
			This option allows to tune the number of preallocated
			entries for DMA-API debugging code. One entry is
			required per DMA-API allocation. Use this if the
			DMA-API debugging code disables itself because the
			architectural default is too low.

	dma_debug_driver=<driver_name>
			With this option the DMA-API debugging driver
			filter feature can be enabled at boot time. Just
			pass the driver to filter for as the parameter.
			The filter can be disabled or changed to another
			driver later using sysfs.

	driver_async_probe=  [KNL]
			List of driver names to be probed asynchronously.
			Format: <driver_name1>,<driver_name2>...

	drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
			Broken monitors, graphic adapters, KVMs and EDIDless
			panels may send no or incorrect EDID data sets.
			This parameter allows to specify an EDID data sets
			in the /lib/firmware directory that are used instead.
			Generic built-in EDID data sets are used, if one of
			edid/1024x768.bin, edid/1280x1024.bin,
			edid/1680x1050.bin, or edid/1920x1080.bin is given
			and no file with the same name exists. Details and
			instructions how to build your own EDID data are
			available in Documentation/admin-guide/edid.rst. An EDID
			data set will only be used for a particular connector,
			if its name and a colon are prepended to the EDID
			name. Each connector may use a unique EDID data
			set by separating the files with a comma.  An EDID
			data set with no connector name will be used for
			any connectors not explicitly specified.

	dscc4.setup=	[NET]

	dt_cpu_ftrs=	[PPC]
			Format: {"off" | "known"}
			Control how the dt_cpu_ftrs device-tree binding is
			used for CPU feature discovery and setup (if it
			exists).
			off: Do not use it, fall back to legacy cpu table.
			known: Do not pass through unknown features to guests
			or userspace, only those that the kernel is aware of.

	dump_apple_properties	[X86]
			Dump name and content of EFI device properties on
			x86 Macs.  Useful for driver authors to determine
			what data is available or for reverse-engineering.

	dyndbg[="val"]		[KNL,DYNAMIC_DEBUG]
	<module>.dyndbg[="val"]
			Enable debug messages at boot time.  See
			Documentation/admin-guide/dynamic-debug-howto.rst
			for details.

	nopku		[X86] Disable Memory Protection Keys CPU feature found
			in some Intel CPUs.

	<module>.async_probe [KNL]
			Enable asynchronous probe on this module.

	early_ioremap_debug [KNL]
			Enable debug messages in early_ioremap support. This
			is useful for tracking down temporary early mappings
			which are not unmapped.

	earlycon=	[KNL] Output early console device and options.

			When used with no options, the early console is
			determined by stdout-path property in device tree's
			chosen node or the ACPI SPCR table if supported by
			the platform.

		cdns,<addr>[,options]
			Start an early, polled-mode console on a Cadence
			(xuartps) serial port at the specified address. Only
			supported option is baud rate. If baud rate is not
			specified, the serial port must already be setup and
			configured.

		uart[8250],io,<addr>[,options]
		uart[8250],mmio,<addr>[,options]
		uart[8250],mmio32,<addr>[,options]
		uart[8250],mmio32be,<addr>[,options]
		uart[8250],0x<addr>[,options]
			Start an early, polled-mode console on the 8250/16550
			UART at the specified I/O port or MMIO address.
			MMIO inter-register address stride is either 8-bit
			(mmio) or 32-bit (mmio32 or mmio32be).
			If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
			to be equivalent to 'mmio'. 'options' are specified
			in the same format described for "console=ttyS<n>"; if
			unspecified, the h/w is not initialized.

		pl011,<addr>
		pl011,mmio32,<addr>
			Start an early, polled-mode console on a pl011 serial
			port at the specified address. The pl011 serial port
			must already be setup and configured. Options are not
			yet supported.  If 'mmio32' is specified, then only
			the driver will use only 32-bit accessors to read/write
			the device registers.

		meson,<addr>
			Start an early, polled-mode console on a meson serial
			port at the specified address. The serial port must
			already be setup and configured. Options are not yet
			supported.

		msm_serial,<addr>
			Start an early, polled-mode console on an msm serial
			port at the specified address. The serial port
			must already be setup and configured. Options are not
			yet supported.

		msm_serial_dm,<addr>
			Start an early, polled-mode console on an msm serial
			dm port at the specified address. The serial port
			must already be setup and configured. Options are not
			yet supported.

		owl,<addr>
			Start an early, polled-mode console on a serial port
			of an Actions Semi SoC, such as S500 or S900, at the
			specified address. The serial port must already be
			setup and configured. Options are not yet supported.

		rda,<addr>
			Start an early, polled-mode console on a serial port
			of an RDA Micro SoC, such as RDA8810PL, at the
			specified address. The serial port must already be
			setup and configured. Options are not yet supported.

		sbi
			Use RISC-V SBI (Supervisor Binary Interface) for early
			console.

		smh	Use ARM semihosting calls for early console.

		s3c2410,<addr>
		s3c2412,<addr>
		s3c2440,<addr>
		s3c6400,<addr>
		s5pv210,<addr>
		exynos4210,<addr>
			Use early console provided by serial driver available
			on Samsung SoCs, requires selecting proper type and
			a correct base address of the selected UART port. The
			serial port must already be setup and configured.
			Options are not yet supported.

		lantiq,<addr>
			Start an early, polled-mode console on a lantiq serial
			(lqasc) port at the specified address. The serial port
			must already be setup and configured. Options are not
			yet supported.

		lpuart,<addr>
		lpuart32,<addr>
			Use early console provided by Freescale LP UART driver
			found on Freescale Vybrid and QorIQ LS1021A processors.
			A valid base address must be provided, and the serial
			port must already be setup and configured.

		ec_imx21,<addr>
		ec_imx6q,<addr>
			Start an early, polled-mode, output-only console on the
			Freescale i.MX UART at the specified address. The UART
			must already be setup and configured.

		ar3700_uart,<addr>
			Start an early, polled-mode console on the
			Armada 3700 serial port at the specified
			address. The serial port must already be setup
			and configured. Options are not yet supported.

		qcom_geni,<addr>
			Start an early, polled-mode console on a Qualcomm
			Generic Interface (GENI) based serial port at the
			specified address. The serial port must already be
			setup and configured. Options are not yet supported.

		efifb,[options]
			Start an early, unaccelerated console on the EFI
			memory mapped framebuffer (if available). On cache
			coherent non-x86 systems that use system memory for
			the framebuffer, pass the 'ram' option so that it is
			mapped with the correct attributes.

		linflex,<addr>
			Use early console provided by Freescale LINFlexD UART
			serial driver for NXP S32V234 SoCs. A valid base
			address must be provided, and the serial port must
			already be setup and configured.

	earlyprintk=	[X86,SH,ARM,M68k,S390]
			earlyprintk=vga
			earlyprintk=sclp
			earlyprintk=xen
			earlyprintk=serial[,ttySn[,baudrate]]
			earlyprintk=serial[,0x...[,baudrate]]
			earlyprintk=ttySn[,baudrate]
			earlyprintk=dbgp[debugController#]
			earlyprintk=pciserial[,force],bus:device.function[,baudrate]
			earlyprintk=xdbc[xhciController#]

			earlyprintk is useful when the kernel crashes before
			the normal console is initialized. It is not enabled by
			default because it has some cosmetic problems.

			Append ",keep" to not disable it when the real console
			takes over.

			Only one of vga, efi, serial, or usb debug port can
			be used at a time.

			Currently only ttyS0 and ttyS1 may be specified by
			name.  Other I/O ports may be explicitly specified
			on some architectures (x86 and arm at least) by
			replacing ttySn with an I/O port address, like this:
				earlyprintk=serial,0x1008,115200
			You can find the port for a given device in
			/proc/tty/driver/serial:
				2: uart:ST16650V2 port:00001008 irq:18 ...

			Interaction with the standard serial driver is not
			very good.

			The VGA and EFI output is eventually overwritten by
			the real console.

			The xen output can only be used by Xen PV guests.

			The sclp output can only be used on s390.

			The optional "force" to "pciserial" enables use of a
			PCI device even when its classcode is not of the
			UART class.

	edac_report=	[HW,EDAC] Control how to report EDAC event
			Format: {"on" | "off" | "force"}
			on: enable EDAC to report H/W event. May be overridden
			by other higher priority error reporting module.
			off: disable H/W event reporting through EDAC.
			force: enforce the use of EDAC to report H/W event.
			default: on.

	ekgdboc=	[X86,KGDB] Allow early kernel console debugging
			ekgdboc=kbd

			This is designed to be used in conjunction with
			the boot argument: earlyprintk=vga

			This parameter works in place of the kgdboc parameter
			but can only be used if the backing tty is available
			very early in the boot process. For early debugging
			via a serial port see kgdboc_earlycon instead.

	edd=		[EDD]
			Format: {"off" | "on" | "skip[mbr]"}

	efi=		[EFI]
			Format: { "debug", "disable_early_pci_dma",
				  "nochunk", "noruntime", "nosoftreserve",
				  "novamap", "no_disable_early_pci_dma" }
			debug: enable misc debug output.
			disable_early_pci_dma: disable the busmaster bit on all
			PCI bridges while in the EFI boot stub.
			nochunk: disable reading files in "chunks" in the EFI
			boot stub, as chunking can cause problems with some
			firmware implementations.
			noruntime : disable EFI runtime services support
			nosoftreserve: The EFI_MEMORY_SP (Specific Purpose)
			attribute may cause the kernel to reserve the
			memory range for a memory mapping driver to
			claim. Specify efi=nosoftreserve to disable this
			reservation and treat the memory by its base type
			(i.e. EFI_CONVENTIONAL_MEMORY / "System RAM").
			novamap: do not call SetVirtualAddressMap().
			no_disable_early_pci_dma: Leave the busmaster bit set
			on all PCI bridges while in the EFI boot stub

	efi_no_storage_paranoia [EFI; X86]
			Using this parameter you can use more than 50% of
			your efi variable storage. Use this parameter only if
			you are really sure that your UEFI does sane gc and
			fulfills the spec otherwise your board may brick.

	efi_fake_mem=	nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86]
			Add arbitrary attribute to specific memory range by
			updating original EFI memory map.
			Region of memory which aa attribute is added to is
			from ss to ss+nn.

			If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
			is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
			attribute is added to range 0x100000000-0x180000000 and
			0x10a0000000-0x1120000000.

			If efi_fake_mem=8G@9G:0x40000 is specified, the
			EFI_MEMORY_SP(0x40000) attribute is added to
			range 0x240000000-0x43fffffff.

			Using this parameter you can do debugging of EFI memmap
			related features. For example, you can do debugging of
			Address Range Mirroring feature even if your box
			doesn't support it, or mark specific memory as
			"soft reserved".

	efivar_ssdt=	[EFI; X86] Name of an EFI variable that contains an SSDT
			that is to be dynamically loaded by Linux. If there are
			multiple variables with the same name but with different
			vendor GUIDs, all of them will be loaded. See
			Documentation/admin-guide/acpi/ssdt-overlays.rst for details.


	eisa_irq_edge=	[PARISC,HW]
			See header of drivers/parisc/eisa.c.

	elanfreq=	[X86-32]
			See comment before function elanfreq_setup() in
			arch/x86/kernel/cpu/cpufreq/elanfreq.c.

	elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
			Specifies physical address of start of kernel core
			image elf header and optionally the size. Generally
			kexec loader will pass this option to capture kernel.
			See Documentation/admin-guide/kdump/kdump.rst for details.

	enable_mtrr_cleanup [X86]
			The kernel tries to adjust MTRR layout from continuous
			to discrete, to make X server driver able to add WB
			entry later. This parameter enables that.

	enable_timer_pin_1 [X86]
			Enable PIN 1 of APIC timer
			Can be useful to work around chipset bugs
			(in particular on some ATI chipsets).
			The kernel tries to set a reasonable default.

	enforcing	[SELINUX] Set initial enforcing status.
			Format: {"0" | "1"}
			See security/selinux/Kconfig help text.
			0 -- permissive (log only, no denials).
			1 -- enforcing (deny and log).
			Default value is 0.
			Value can be changed at runtime via
			/sys/fs/selinux/enforce.

	erst_disable	[ACPI]
			Disable Error Record Serialization Table (ERST)
			support.

	ether=		[HW,NET] Ethernet cards parameters
			This option is obsoleted by the "netdev=" option, which
			has equivalent usage. See its documentation for details.

	evm=		[EVM]
			Format: { "fix" }
			Permit 'security.evm' to be updated regardless of
			current integrity status.

	failslab=
	fail_usercopy=
	fail_page_alloc=
	fail_make_request=[KNL]
			General fault injection mechanism.
			Format: <interval>,<probability>,<space>,<times>
			See also Documentation/fault-injection/.

	fb_tunnels=	[NET]
			Format: { initns | none }
			See Documentation/admin-guide/sysctl/net.rst for
			fb_tunnels_only_for_init_ns

	floppy=		[HW]
			See Documentation/admin-guide/blockdev/floppy.rst.

	force_pal_cache_flush
			[IA-64] Avoid check_sal_cache_flush which may hang on
			buggy SAL_CACHE_FLUSH implementations. Using this
			parameter will force ia64_sal_cache_flush to call
			ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.

	forcepae	[X86-32]
			Forcefully enable Physical Address Extension (PAE).
			Many Pentium M systems disable PAE but may have a
			functionally usable PAE implementation.
			Warning: use of this parameter will taint the kernel
			and may cause unknown problems.

	ftrace=[tracer]
			[FTRACE] will set and start the specified tracer
			as early as possible in order to facilitate early
			boot debugging.

	ftrace_dump_on_oops[=orig_cpu]
			[FTRACE] will dump the trace buffers on oops.
			If no parameter is passed, ftrace will dump
			buffers of all CPUs, but if you pass orig_cpu, it will
			dump only the buffer of the CPU that triggered the
			oops.

	ftrace_filter=[function-list]
			[FTRACE] Limit the functions traced by the function
			tracer at boot up. function-list is a comma separated
			list of functions. This list can be changed at run
			time by the set_ftrace_filter file in the debugfs
			tracing directory.

	ftrace_notrace=[function-list]
			[FTRACE] Do not trace the functions specified in
			function-list. This list can be changed at run time
			by the set_ftrace_notrace file in the debugfs
			tracing directory.

	ftrace_graph_filter=[function-list]
			[FTRACE] Limit the top level callers functions traced
			by the function graph tracer at boot up.
			function-list is a comma separated list of functions
			that can be changed at run time by the
			set_graph_function file in the debugfs tracing directory.

	ftrace_graph_notrace=[function-list]
			[FTRACE] Do not trace from the functions specified in
			function-list.  This list is a comma separated list of
			functions that can be changed at run time by the
			set_graph_notrace file in the debugfs tracing directory.

	ftrace_graph_max_depth=<uint>
			[FTRACE] Used with the function graph tracer. This is
			the max depth it will trace into a function. This value
			can be changed at run time by the max_graph_depth file
			in the tracefs tracing directory. default: 0 (no limit)

	fw_devlink=	[KNL] Create device links between consumer and supplier
			devices by scanning the firmware to infer the
			consumer/supplier relationships. This feature is
			especially useful when drivers are loaded as modules as
			it ensures proper ordering of tasks like device probing
			(suppliers first, then consumers), supplier boot state
			clean up (only after all consumers have probed),
			suspend/resume & runtime PM (consumers first, then
			suppliers).
			Format: { off | permissive | on | rpm }
			off --	Don't create device links from firmware info.
			permissive -- Create device links from firmware info
				but use it only for ordering boot state clean
				up (sync_state() calls).
			on -- 	Create device links from firmware info and use it
				to enforce probe and suspend/resume ordering.
			rpm --	Like "on", but also use to order runtime PM.

	gamecon.map[2|3]=
			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
			support via parallel port (up to 5 devices per port)
			Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
			See also Documentation/input/devices/joystick-parport.rst

	gamma=		[HW,DRM]

	gart_fix_e820=	[X86-64] disable the fix e820 for K8 GART
			Format: off | on
			default: on

	gcov_persist=	[GCOV] When non-zero (default), profiling data for
			kernel modules is saved and remains accessible via
			debugfs, even when the module is unloaded/reloaded.
			When zero, profiling data is discarded and associated
			debugfs files are removed at module unload time.

	goldfish	[X86] Enable the goldfish android emulator platform.
			Don't use this when you are not running on the
			android emulator

	gpt		[EFI] Forces disk with valid GPT signature but
			invalid Protective MBR to be treated as GPT. If the
			primary GPT is corrupted, it enables the backup/alternate
			GPT to be used instead.

	grcan.enable0=	[HW] Configuration of physical interface 0. Determines
			the "Enable 0" bit of the configuration register.
			Format: 0 | 1
			Default: 0
	grcan.enable1=	[HW] Configuration of physical interface 1. Determines
			the "Enable 0" bit of the configuration register.
			Format: 0 | 1
			Default: 0
	grcan.select=	[HW] Select which physical interface to use.
			Format: 0 | 1
			Default: 0
	grcan.txsize=	[HW] Sets the size of the tx buffer.
			Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
			Default: 1024
	grcan.rxsize=	[HW] Sets the size of the rx buffer.
			Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
			Default: 1024

	gpio-mockup.gpio_mockup_ranges
			[HW] Sets the ranges of gpiochip of for this device.
			Format: <start1>,<end1>,<start2>,<end2>...

	hardlockup_all_cpu_backtrace=
			[KNL] Should the hard-lockup detector generate
			backtraces on all cpus.
			Format: 0 | 1

	hashdist=	[KNL,NUMA] Large hashes allocated during boot
			are distributed across NUMA nodes.  Defaults on
			for 64-bit NUMA, off otherwise.
			Format: 0 | 1 (for off | on)

	hcl=		[IA-64] SGI's Hardware Graph compatibility layer

	hd=		[EIDE] (E)IDE hard drive subsystem geometry
			Format: <cyl>,<head>,<sect>

	hest_disable	[ACPI]
			Disable Hardware Error Source Table (HEST) support;
			corresponding firmware-first mode error processing
			logic will be disabled.

	highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
			size of <nn>. This works even on boxes that have no
			highmem otherwise. This also works to reduce highmem
			size on bigger boxes.

	highres=	[KNL] Enable/disable high resolution timer mode.
			Valid parameters: "on", "off"
			Default: "on"

	hlt		[BUGS=ARM,SH]

	hpet=		[X86-32,HPET] option to control HPET usage
			Format: { enable (default) | disable | force |
				verbose }
			disable: disable HPET and use PIT instead
			force: allow force enabled of undocumented chips (ICH4,
				VIA, nVidia)
			verbose: show contents of HPET registers during setup

	hpet_mmap=	[X86, HPET_MMAP] Allow userspace to mmap HPET
			registers.  Default set by CONFIG_HPET_MMAP_DEFAULT.

	hugetlb_cma=	[HW] The size of a cma area used for allocation
			of gigantic hugepages.
			Format: nn[KMGTPE]

			Reserve a cma area of given size and allocate gigantic
			hugepages using the cma allocator. If enabled, the
			boot-time allocation of gigantic hugepages is skipped.

	hugepages=	[HW] Number of HugeTLB pages to allocate at boot.
			If this follows hugepagesz (below), it specifies
			the number of pages of hugepagesz to be allocated.
			If this is the first HugeTLB parameter on the command
			line, it specifies the number of pages to allocate for
			the default huge page size.  See also
			Documentation/admin-guide/mm/hugetlbpage.rst.
			Format: <integer>

	hugepagesz=
			[HW] The size of the HugeTLB pages.  This is used in
			conjunction with hugepages (above) to allocate huge
			pages of a specific size at boot.  The pair
			hugepagesz=X hugepages=Y can be specified once for
			each supported huge page size. Huge page sizes are
			architecture dependent.  See also
			Documentation/admin-guide/mm/hugetlbpage.rst.
			Format: size[KMG]

	hung_task_panic=
			[KNL] Should the hung task detector generate panics.
			Format: 0 | 1

			A value of 1 instructs the kernel to panic when a
			hung task is detected. The default value is controlled
			by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
			option. The value selected by this boot parameter can
			be changed later by the kernel.hung_task_panic sysctl.

	hvc_iucv=	[S390]	Number of z/VM IUCV hypervisor console (HVC)
				terminal devices. Valid values: 0..8
	hvc_iucv_allow=	[S390]	Comma-separated list of z/VM user IDs.
				If specified, z/VM IUCV HVC accepts connections
				from listed z/VM user IDs only.

	hv_nopvspin	[X86,HYPER_V] Disables the paravirt spinlock optimizations
				      which allow the hypervisor to 'idle' the
				      guest on lock contention.

	keep_bootcon	[KNL]
			Do not unregister boot console at start. This is only
			useful for debugging when something happens in the window
			between unregistering the boot console and initializing
			the real console.

	i2c_bus=	[HW]	Override the default board specific I2C bus speed
				or register an additional I2C bus that is not
				registered from board initialization code.
				Format:
				<bus_id>,<clkrate>

	i8042.debug	[HW] Toggle i8042 debug mode
	i8042.unmask_kbd_data
			[HW] Enable printing of interrupt data from the KBD port
			     (disabled by default, and as a pre-condition
			     requires that i8042.debug=1 be enabled)
	i8042.direct	[HW] Put keyboard port into non-translated mode
	i8042.dumbkbd	[HW] Pretend that controller can only read data from
			     keyboard and cannot control its state
			     (Don't attempt to blink the leds)
	i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
	i8042.nokbd	[HW] Don't check/create keyboard port
	i8042.noloop	[HW] Disable the AUX Loopback command while probing
			     for the AUX port
	i8042.nomux	[HW] Don't check presence of an active multiplexing
			     controller
	i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
			     controllers
	i8042.notimeout	[HW] Ignore timeout condition signalled by controller
	i8042.reset	[HW] Reset the controller during init, cleanup and
			     suspend-to-ram transitions, only during s2r
			     transitions, or never reset
			Format: { 1 | Y | y | 0 | N | n }
			1, Y, y: always reset controller
			0, N, n: don't ever reset controller
			Default: only on s2r transitions on x86; most other
			architectures force reset to be always executed
	i8042.unlock	[HW] Unlock (ignore) the keylock
	i8042.kbdreset	[HW] Reset device connected to KBD port

	i810=		[HW,DRM]

	i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
			indicates that the driver is running on unsupported
			hardware.
	i8k.force	[HW] Activate i8k driver even if SMM BIOS signature
			does not match list of supported models.
	i8k.power_status
			[HW] Report power status in /proc/i8k
			(disabled by default)
	i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN
			capability is set.

	i915.invert_brightness=
			[DRM] Invert the sense of the variable that is used to
			set the brightness of the panel backlight. Normally a
			brightness value of 0 indicates backlight switched off,
			and the maximum of the brightness value sets the backlight
			to maximum brightness. If this parameter is set to 0
			(default) and the machine requires it, or this parameter
			is set to 1, a brightness value of 0 sets the backlight
			to maximum brightness, and the maximum of the brightness
			value switches the backlight off.
			-1 -- never invert brightness
			 0 -- machine default
			 1 -- force brightness inversion

	icn=		[HW,ISDN]
			Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]

	ide-core.nodma=	[HW] (E)IDE subsystem
			Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
			.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
			.cdrom .chs .ignore_cable are additional options
			See Documentation/ide/ide.rst.

	ide-generic.probe-mask= [HW] (E)IDE subsystem
			Format: <int>
			Probe mask for legacy ISA IDE ports.  Depending on
			platform up to 6 ports are supported, enabled by
			setting corresponding bits in the mask to 1.  The
			default value is 0x0, which has a special meaning.
			On systems that have PCI, it triggers scanning the
			PCI bus for the first and the second port, which
			are then probed.  On systems without PCI the value
			of 0x0 enables probing the two first ports as if it
			was 0x3.

	ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
			Claim all unknown PCI IDE storage controllers.

	idle=		[X86]
			Format: idle=poll, idle=halt, idle=nomwait
			Poll forces a polling idle loop that can slightly
			improve the performance of waking up a idle CPU, but
			will use a lot of power and make the system run hot.
			Not recommended.
			idle=halt: Halt is forced to be used for CPU idle.
			In such case C2/C3 won't be used again.
			idle=nomwait: Disable mwait for CPU C-states

	ieee754=	[MIPS] Select IEEE Std 754 conformance mode
			Format: { strict | legacy | 2008 | relaxed }
			Default: strict

			Choose which programs will be accepted for execution
			based on the IEEE 754 NaN encoding(s) supported by
			the FPU and the NaN encoding requested with the value
			of an ELF file header flag individually set by each
			binary.  Hardware implementations are permitted to
			support either or both of the legacy and the 2008 NaN
			encoding mode.

			Available settings are as follows:
			strict	accept binaries that request a NaN encoding
				supported by the FPU
			legacy	only accept legacy-NaN binaries, if supported
				by the FPU
			2008	only accept 2008-NaN binaries, if supported
				by the FPU
			relaxed	accept any binaries regardless of whether
				supported by the FPU

			The FPU emulator is always able to support both NaN
			encodings, so if no FPU hardware is present or it has
			been disabled with 'nofpu', then the settings of
			'legacy' and '2008' strap the emulator accordingly,
			'relaxed' straps the emulator for both legacy-NaN and
			2008-NaN, whereas 'strict' enables legacy-NaN only on
			legacy processors and both NaN encodings on MIPS32 or
			MIPS64 CPUs.

			The setting for ABS.fmt/NEG.fmt instruction execution
			mode generally follows that for the NaN encoding,
			except where unsupported by hardware.

	ignore_loglevel	[KNL]
			Ignore loglevel setting - this will print /all/
			kernel messages to the console. Useful for debugging.
			We also add it as printk module parameter, so users
			could change it dynamically, usually by
			/sys/module/printk/parameters/ignore_loglevel.

	ignore_rlimit_data
			Ignore RLIMIT_DATA setting for data mappings,
			print warning at first misuse.  Can be changed via
			/sys/module/kernel/parameters/ignore_rlimit_data.

	ihash_entries=	[KNL]
			Set number of hash buckets for inode cache.

	ima_appraise=	[IMA] appraise integrity measurements
			Format: { "off" | "enforce" | "fix" | "log" }
			default: "enforce"

	ima_appraise_tcb [IMA] Deprecated.  Use ima_policy= instead.
			The builtin appraise policy appraises all files
			owned by uid=0.

	ima_canonical_fmt [IMA]
			Use the canonical format for the binary runtime
			measurements, instead of host native format.

	ima_hash=	[IMA]
			Format: { md5 | sha1 | rmd160 | sha256 | sha384
				   | sha512 | ... }
			default: "sha1"

			The list of supported hash algorithms is defined
			in crypto/hash_info.h.

	ima_policy=	[IMA]
			The builtin policies to load during IMA setup.
			Format: "tcb | appraise_tcb | secure_boot |
				 fail_securely"

			The "tcb" policy measures all programs exec'd, files
			mmap'd for exec, and all files opened with the read
			mode bit set by either the effective uid (euid=0) or
			uid=0.

			The "appraise_tcb" policy appraises the integrity of
			all files owned by root.

			The "secure_boot" policy appraises the integrity
			of files (eg. kexec kernel image, kernel modules,
			firmware, policy, etc) based on file signatures.

			The "fail_securely" policy forces file signature
			verification failure also on privileged mounted
			filesystems with the SB_I_UNVERIFIABLE_SIGNATURE
			flag.

	ima_tcb		[IMA] Deprecated.  Use ima_policy= instead.
			Load a policy which meets the needs of the Trusted
			Computing Base.  This means IMA will measure all
			programs exec'd, files mmap'd for exec, and all files
			opened for read by uid=0.

	ima_template=	[IMA]
			Select one of defined IMA measurements template formats.
			Formats: { "ima" | "ima-ng" | "ima-sig" }
			Default: "ima-ng"

	ima_template_fmt=
			[IMA] Define a custom template format.
			Format: { "field1|...|fieldN" }

	ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
			Format: <min_file_size>
			Set the minimal file size for using asynchronous hash.
			If left unspecified, ahash usage is disabled.

			ahash performance varies for different data sizes on
			different crypto accelerators. This option can be used
			to achieve the best performance for a particular HW.

	ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
			Format: <bufsize>
			Set hashing buffer size. Default: 4k.

			ahash performance varies for different chunk sizes on
			different crypto accelerators. This option can be used
			to achieve best performance for particular HW.

	init=		[KNL]
			Format: <full_path>
			Run specified binary instead of /sbin/init as init
			process.

	initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
			for working out where the kernel is dying during
			startup.

	initcall_blacklist=  [KNL] Do not execute a comma-separated list of
			initcall functions.  Useful for debugging built-in
			modules and initcalls.

	initrd=		[BOOT] Specify the location of the initial ramdisk

	initrdmem=	[KNL] Specify a physical address and size from which to
			load the initrd. If an initrd is compiled in or
			specified in the bootparams, it takes priority over this
			setting.
			Format: ss[KMG],nn[KMG]
			Default is 0, 0

	init_on_alloc=	[MM] Fill newly allocated pages and heap objects with
			zeroes.
			Format: 0 | 1
			Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON.

	init_on_free=	[MM] Fill freed pages and heap objects with zeroes.
			Format: 0 | 1
			Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON.

	init_pkru=	[X86] Specify the default memory protection keys rights
			register contents for all processes.  0x55555554 by
			default (disallow access to all but pkey 0).  Can
			override in debugfs after boot.

	inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
			Format: <irq>

	int_pln_enable	[X86] Enable power limit notification interrupt

	integrity_audit=[IMA]
			Format: { "0" | "1" }
			0 -- basic integrity auditing messages. (Default)
			1 -- additional integrity auditing messages.

	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
		on
			Enable intel iommu driver.
		off
			Disable intel iommu driver.
		igfx_off [Default Off]
			By default, gfx is mapped as normal device. If a gfx
			device has a dedicated DMAR unit, the DMAR unit is
			bypassed by not enabling DMAR with this option. In
			this case, gfx device will use physical address for
			DMA.
		forcedac [X86-64]
			With this option iommu will not optimize to look
			for io virtual address below 32-bit forcing dual
			address cycle on pci bus for cards supporting greater
			than 32-bit addressing. The default is to look
			for translation below 32-bit and if not available
			then look in the higher range.
		strict [Default Off]
			With this option on every unmap_single operation will
			result in a hardware IOTLB flush operation as opposed
			to batching them for performance.
		sp_off [Default Off]
			By default, super page will be supported if Intel IOMMU
			has the capability. With this option, super page will
			not be supported.
		sm_on [Default Off]
			By default, scalable mode will be disabled even if the
			hardware advertises that it has support for the scalable
			mode translation. With this option set, scalable mode
			will be used on hardware which claims to support it.
		tboot_noforce [Default Off]
			Do not force the Intel IOMMU enabled under tboot.
			By default, tboot will force Intel IOMMU on, which
			could harm performance of some high-throughput
			devices like 40GBit network cards, even if identity
			mapping is enabled.
			Note that using this option lowers the security
			provided by tboot because it makes the system
			vulnerable to DMA attacks.
		nobounce [Default off]
			Disable bounce buffer for untrusted devices such as
			the Thunderbolt devices. This will treat the untrusted
			devices as the trusted ones, hence might expose security
			risks of DMA attacks.

	intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
			0	disables intel_idle and fall back on acpi_idle.
			1 to 9	specify maximum depth of C-state.

	intel_pstate=	[X86]
			disable
			  Do not enable intel_pstate as the default
			  scaling driver for the supported processors
			passive
			  Use intel_pstate as a scaling driver, but configure it
			  to work with generic cpufreq governors (instead of
			  enabling its internal governor).  This mode cannot be
			  used along with the hardware-managed P-states (HWP)
			  feature.
			force
			  Enable intel_pstate on systems that prohibit it by default
			  in favor of acpi-cpufreq. Forcing the intel_pstate driver
			  instead of acpi-cpufreq may disable platform features, such
			  as thermal controls and power capping, that rely on ACPI
			  P-States information being indicated to OSPM and therefore
			  should be used with caution. This option does not work with
			  processors that aren't supported by the intel_pstate driver
			  or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
			no_hwp
			  Do not enable hardware P state control (HWP)
			  if available.
			hwp_only
			  Only load intel_pstate on systems which support
			  hardware P state control (HWP) if available.
			support_acpi_ppc
			  Enforce ACPI _PPC performance limits. If the Fixed ACPI
			  Description Table, specifies preferred power management
			  profile as "Enterprise Server" or "Performance Server",
			  then this feature is turned on by default.
			per_cpu_perf_limits
			  Allow per-logical-CPU P-State performance control limits using
			  cpufreq sysfs interface

	intremap=	[X86-64, Intel-IOMMU]
			on	enable Interrupt Remapping (default)
			off	disable Interrupt Remapping
			nosid	disable Source ID checking
			no_x2apic_optout
				BIOS x2APIC opt-out request will be ignored
			nopost	disable Interrupt Posting

	iomem=		Disable strict checking of access to MMIO memory
		strict	regions from userspace.
		relaxed

	iommu=		[X86]
		off
		force
		noforce
		biomerge
		panic
		nopanic
		merge
		nomerge
		soft
		pt		[X86]
		nopt		[X86]
		nobypass	[PPC/POWERNV]
			Disable IOMMU bypass, using IOMMU for PCI devices.

	iommu.strict=	[ARM64] Configure TLB invalidation behaviour
			Format: { "0" | "1" }
			0 - Lazy mode.
			  Request that DMA unmap operations use deferred
			  invalidation of hardware TLBs, for increased
			  throughput at the cost of reduced device isolation.
			  Will fall back to strict mode if not supported by
			  the relevant IOMMU driver.
			1 - Strict mode (default).
			  DMA unmap operations invalidate IOMMU hardware TLBs
			  synchronously.

	iommu.passthrough=
			[ARM64, X86] Configure DMA to bypass the IOMMU by default.
			Format: { "0" | "1" }
			0 - Use IOMMU translation for DMA.
			1 - Bypass the IOMMU for DMA.
			unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.

	io7=		[HW] IO7 for Marvel-based Alpha systems
			See comment before marvel_specify_io7 in
			arch/alpha/kernel/core_marvel.c.

	io_delay=	[X86] I/O delay method
		0x80
			Standard port 0x80 based delay
		0xed
			Alternate port 0xed based delay (needed on some systems)
		udelay
			Simple two microseconds delay
		none
			No delay

	ip=		[IP_PNP]
			See Documentation/admin-guide/nfs/nfsroot.rst.

	ipcmni_extend	[KNL] Extend the maximum number of unique System V
			IPC identifiers from 32,768 to 16,777,216.

	irqaffinity=	[SMP] Set the default irq affinity mask
			The argument is a cpu list, as described above.

	irqchip.gicv2_force_probe=
			[ARM, ARM64]
			Format: <bool>
			Force the kernel to look for the second 4kB page
			of a GICv2 controller even if the memory range
			exposed by the device tree is too small.

	irqchip.gicv3_nolpi=
			[ARM, ARM64]
			Force the kernel to ignore the availability of
			LPIs (and by consequence ITSs). Intended for system
			that use the kernel as a bootloader, and thus want
			to let secondary kernels in charge of setting up
			LPIs.

	irqchip.gicv3_pseudo_nmi= [ARM64]
			Enables support for pseudo-NMIs in the kernel. This
			requires the kernel to be built with
			CONFIG_ARM64_PSEUDO_NMI.

	irqfixup	[HW]
			When an interrupt is not handled search all handlers
			for it. Intended to get systems with badly broken
			firmware running.

	irqpoll		[HW]
			When an interrupt is not handled search all handlers
			for it. Also check all handlers each timer
			interrupt. Intended to get systems with badly broken
			firmware running.

	isapnp=		[ISAPNP]
			Format: <RDP>,<reset>,<pci_scan>,<verbosity>

	isolcpus=	[KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
			[Deprecated - use cpusets instead]
			Format: [flag-list,]<cpu-list>

			Specify one or more CPUs to isolate from disturbances
			specified in the flag list (default: domain):

			nohz
			  Disable the tick when a single task runs.

			  A residual 1Hz tick is offloaded to workqueues, which you
			  need to affine to housekeeping through the global
			  workqueue's affinity configured via the
			  /sys/devices/virtual/workqueue/cpumask sysfs file, or
			  by using the 'domain' flag described below.

			  NOTE: by default the global workqueue runs on all CPUs,
			  so to protect individual CPUs the 'cpumask' file has to
			  be configured manually after bootup.

			domain
			  Isolate from the general SMP balancing and scheduling
			  algorithms. Note that performing domain isolation this way
			  is irreversible: it's not possible to bring back a CPU to
			  the domains once isolated through isolcpus. It's strongly
			  advised to use cpusets instead to disable scheduler load
			  balancing through the "cpuset.sched_load_balance" file.
			  It offers a much more flexible interface where CPUs can
			  move in and out of an isolated set anytime.

			  You can move a process onto or off an "isolated" CPU via
			  the CPU affinity syscalls or cpuset.
			  <cpu number> begins at 0 and the maximum value is
			  "number of CPUs in system - 1".

			managed_irq

			  Isolate from being targeted by managed interrupts
			  which have an interrupt mask containing isolated
			  CPUs. The affinity of managed interrupts is
			  handled by the kernel and cannot be changed via
			  the /proc/irq/* interfaces.

			  This isolation is best effort and only effective
			  if the automatically assigned interrupt mask of a
			  device queue contains isolated and housekeeping
			  CPUs. If housekeeping CPUs are online then such
			  interrupts are directed to the housekeeping CPU
			  so that IO submitted on the housekeeping CPU
			  cannot disturb the isolated CPU.

			  If a queue's affinity mask contains only isolated
			  CPUs then this parameter has no effect on the
			  interrupt routing decision, though interrupts are
			  only delivered when tasks running on those
			  isolated CPUs submit IO. IO submitted on
			  housekeeping CPUs has no influence on those
			  queues.

			The format of <cpu-list> is described above.

	iucv=		[HW,NET]

	ivrs_ioapic	[HW,X86-64]
			Provide an override to the IOAPIC-ID<->DEVICE-ID
			mapping provided in the IVRS ACPI table. For
			example, to map IOAPIC-ID decimal 10 to
			PCI device 00:14.0 write the parameter as:
				ivrs_ioapic[10]=00:14.0

	ivrs_hpet	[HW,X86-64]
			Provide an override to the HPET-ID<->DEVICE-ID
			mapping provided in the IVRS ACPI table. For
			example, to map HPET-ID decimal 0 to
			PCI device 00:14.0 write the parameter as:
				ivrs_hpet[0]=00:14.0

	ivrs_acpihid	[HW,X86-64]
			Provide an override to the ACPI-HID:UID<->DEVICE-ID
			mapping provided in the IVRS ACPI table. For
			example, to map UART-HID:UID AMD0020:0 to
			PCI device 00:14.5 write the parameter as:
				ivrs_acpihid[00:14.5]=AMD0020:0

	js=		[HW,JOY] Analog joystick
			See Documentation/input/joydev/joystick.rst.

	nokaslr		[KNL]
			When CONFIG_RANDOMIZE_BASE is set, this disables
			kernel and module base offset ASLR (Address Space
			Layout Randomization).

	kasan_multi_shot
			[KNL] Enforce KASAN (Kernel Address Sanitizer) to print
			report on every invalid memory access. Without this
			parameter KASAN will print report only for the first
			invalid access.

	keepinitrd	[HW,ARM]

	kernelcore=	[KNL,X86,IA-64,PPC]
			Format: nn[KMGTPE] | nn% | "mirror"
			This parameter specifies the amount of memory usable by
			the kernel for non-movable allocations.  The requested
			amount is spread evenly throughout all nodes in the
			system as ZONE_NORMAL.  The remaining memory is used for
			movable memory in its own zone, ZONE_MOVABLE.  In the
			event, a node is too small to have both ZONE_NORMAL and
			ZONE_MOVABLE, kernelcore memory will take priority and
			other nodes will have a larger ZONE_MOVABLE.

			ZONE_MOVABLE is used for the allocation of pages that
			may be reclaimed or moved by the page migration
			subsystem.  Note that allocations like PTEs-from-HighMem
			still use the HighMem zone if it exists, and the Normal
			zone if it does not.

			It is possible to specify the exact amount of memory in
			the form of "nn[KMGTPE]", a percentage of total system
			memory in the form of "nn%", or "mirror".  If "mirror"
			option is specified, mirrored (reliable) memory is used
			for non-movable allocations and remaining memory is used
			for Movable pages.  "nn[KMGTPE]", "nn%", and "mirror"
			are exclusive, so you cannot specify multiple forms.

	kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
			Format: <Controller#>[,poll interval]
			The controller # is the number of the ehci usb debug
			port as it is probed via PCI.  The poll interval is
			optional and is the number seconds in between
			each poll cycle to the debug port in case you need
			the functionality for interrupting the kernel with
			gdb or control-c on the dbgp connection.  When
			not using this parameter you use sysrq-g to break into
			the kernel debugger.

	kgdboc=		[KGDB,HW] kgdb over consoles.
			Requires a tty driver that supports console polling,
			or a supported polling keyboard driver (non-usb).
			 Serial only format: <serial_device>[,baud]
			 keyboard only format: kbd
			 keyboard and serial format: kbd,<serial_device>[,baud]
			Optional Kernel mode setting:
			 kms, kbd format: kms,kbd
			 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]

	kgdboc_earlycon=	[KGDB,HW]
			If the boot console provides the ability to read
			characters and can work in polling mode, you can use
			this parameter to tell kgdb to use it as a backend
			until the normal console is registered. Intended to
			be used together with the kgdboc parameter which
			specifies the normal console to transition to.

			The name of the early console should be specified
			as the value of this parameter. Note that the name of
			the early console might be different than the tty
			name passed to kgdboc. It's OK to leave the value
			blank and the first boot console that implements
			read() will be picked.

	kgdbwait	[KGDB] Stop kernel execution and enter the
			kernel debugger at the earliest opportunity.

	kmac=		[MIPS] Korina ethernet MAC address.
			Configure the RouterBoard 532 series on-chip
			Ethernet adapter MAC address.

	kmemleak=	[KNL] Boot-time kmemleak enable/disable
			Valid arguments: on, off
			Default: on
			Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
			the default is off.

	kprobe_event=[probe-list]
			[FTRACE] Add kprobe events and enable at boot time.
			The probe-list is a semicolon delimited list of probe
			definitions. Each definition is same as kprobe_events
			interface, but the parameters are comma delimited.
			For example, to add a kprobe event on vfs_read with
			arg1 and arg2, add to the command line;

			      kprobe_event=p,vfs_read,$arg1,$arg2

			See also Documentation/trace/kprobetrace.rst "Kernel
			Boot Parameter" section.

	kpti=		[ARM64] Control page table isolation of user
			and kernel address spaces.
			Default: enabled on cores which need mitigation.
			0: force disabled
			1: force enabled

	kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
			Default is 0 (don't ignore, but inject #GP)

	kvm.enable_vmware_backdoor=[KVM] Support VMware backdoor PV interface.
				   Default is false (don't support).

	kvm.mmu_audit=	[KVM] This is a R/W parameter which allows audit
			KVM MMU at runtime.
			Default is 0 (off)

	kvm.nx_huge_pages=
			[KVM] Controls the software workaround for the
			X86_BUG_ITLB_MULTIHIT bug.
			force	: Always deploy workaround.
			off	: Never deploy workaround.
			auto    : Deploy workaround based on the presence of
				  X86_BUG_ITLB_MULTIHIT.

			Default is 'auto'.

			If the software workaround is enabled for the host,
			guests do need not to enable it for nested guests.

	kvm.nx_huge_pages_recovery_ratio=
			[KVM] Controls how many 4KiB pages are periodically zapped
			back to huge pages.  0 disables the recovery, otherwise if
			the value is N KVM will zap 1/Nth of the 4KiB pages every
			minute.  The default is 60.

	kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.
			Default is 1 (enabled)

	kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)
			for all guests.
			Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.

	kvm-arm.vgic_v3_group0_trap=
			[KVM,ARM] Trap guest accesses to GICv3 group-0
			system registers

	kvm-arm.vgic_v3_group1_trap=
			[KVM,ARM] Trap guest accesses to GICv3 group-1
			system registers

	kvm-arm.vgic_v3_common_trap=
			[KVM,ARM] Trap guest accesses to GICv3 common
			system registers

	kvm-arm.vgic_v4_enable=
			[KVM,ARM] Allow use of GICv4 for direct injection of
			LPIs.

	kvm_cma_resv_ratio=n [PPC]
			Reserves given percentage from system memory area for
			contiguous memory allocation for KVM hash pagetable
			allocation.
			By default it reserves 5% of total system memory.
			Format: <integer>
			Default: 5

	kvm-intel.ept=	[KVM,Intel] Disable extended page tables
			(virtualized MMU) support on capable Intel chips.
			Default is 1 (enabled)

	kvm-intel.emulate_invalid_guest_state=
			[KVM,Intel] Enable emulation of invalid guest states
			Default is 0 (disabled)

	kvm-intel.flexpriority=
			[KVM,Intel] Disable FlexPriority feature (TPR shadow).
			Default is 1 (enabled)

	kvm-intel.nested=
			[KVM,Intel] Enable VMX nesting (nVMX).
			Default is 0 (disabled)

	kvm-intel.unrestricted_guest=
			[KVM,Intel] Disable unrestricted guest feature
			(virtualized real and unpaged mode) on capable
			Intel chips. Default is 1 (enabled)

	kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
			CVE-2018-3620.

			Valid arguments: never, cond, always

			always: L1D cache flush on every VMENTER.
			cond:	Flush L1D on VMENTER only when the code between
				VMEXIT and VMENTER can leak host memory.
			never:	Disables the mitigation

			Default is cond (do L1 cache flush in specific instances)

	kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification
			feature (tagged TLBs) on capable Intel chips.
			Default is 1 (enabled)

	l1tf=           [X86] Control mitigation of the L1TF vulnerability on
			      affected CPUs

			The kernel PTE inversion protection is unconditionally
			enabled and cannot be disabled.

			full
				Provides all available mitigations for the
				L1TF vulnerability. Disables SMT and
				enables all mitigations in the
				hypervisors, i.e. unconditional L1D flush.

				SMT control and L1D flush control via the
				sysfs interface is still possible after
				boot.  Hypervisors will issue a warning
				when the first VM is started in a
				potentially insecure configuration,
				i.e. SMT enabled or L1D flush disabled.

			full,force
				Same as 'full', but disables SMT and L1D
				flush runtime control. Implies the
				'nosmt=force' command line option.
				(i.e. sysfs control of SMT is disabled.)

			flush
				Leaves SMT enabled and enables the default
				hypervisor mitigation, i.e. conditional
				L1D flush.

				SMT control and L1D flush control via the
				sysfs interface is still possible after
				boot.  Hypervisors will issue a warning
				when the first VM is started in a
				potentially insecure configuration,
				i.e. SMT enabled or L1D flush disabled.

			flush,nosmt

				Disables SMT and enables the default
				hypervisor mitigation.

				SMT control and L1D flush control via the
				sysfs interface is still possible after
				boot.  Hypervisors will issue a warning
				when the first VM is started in a
				potentially insecure configuration,
				i.e. SMT enabled or L1D flush disabled.

			flush,nowarn
				Same as 'flush', but hypervisors will not
				warn when a VM is started in a potentially
				insecure configuration.

			off
				Disables hypervisor mitigations and doesn't
				emit any warnings.
				It also drops the swap size and available
				RAM limit restriction on both hypervisor and
				bare metal.

			Default is 'flush'.

			For details see: Documentation/admin-guide/hw-vuln/l1tf.rst

	l2cr=		[PPC]

	l3cr=		[PPC]

	lapic		[X86-32,APIC] Enable the local APIC even if BIOS
			disabled it.

	lapic=		[X86,APIC] Do not use TSC deadline
			value for LAPIC timer one-shot implementation. Default
			back to the programmable timer unit in the LAPIC.
			Format: notscdeadline

	lapic_timer_c2_ok	[X86,APIC] trust the local apic timer
			in C2 power state.

	libata.dma=	[LIBATA] DMA control
			libata.dma=0	  Disable all PATA and SATA DMA
			libata.dma=1	  PATA and SATA Disk DMA only
			libata.dma=2	  ATAPI (CDROM) DMA only
			libata.dma=4	  Compact Flash DMA only
			Combinations also work, so libata.dma=3 enables DMA
			for disks and CDROMs, but not CFs.

	libata.ignore_hpa=	[LIBATA] Ignore HPA limit
			libata.ignore_hpa=0	  keep BIOS limits (default)
			libata.ignore_hpa=1	  ignore limits, using full disk

	libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
			when set.
			Format: <int>

	libata.force=	[LIBATA] Force configurations.  The format is comma
			separated list of "[ID:]VAL" where ID is
			PORT[.DEVICE].  PORT and DEVICE are decimal numbers
			matching port, link or device.  Basically, it matches
			the ATA ID string printed on console by libata.  If
			the whole ID part is omitted, the last PORT and DEVICE
			values are used.  If ID hasn't been specified yet, the
			configuration applies to all ports, links and devices.

			If only DEVICE is omitted, the parameter applies to
			the port and all links and devices behind it.  DEVICE
			number of 0 either selects the first device or the
			first fan-out link behind PMP device.  It does not
			select the host link.  DEVICE number of 15 selects the
			host link and device attached to it.

			The VAL specifies the configuration to force.  As long
			as there's no ambiguity shortcut notation is allowed.
			For example, both 1.5 and 1.5G would work for 1.5Gbps.
			The following configurations can be forced.

			* Cable type: 40c, 80c, short40c, unk, ign or sata.
			  Any ID with matching PORT is used.

			* SATA link speed limit: 1.5Gbps or 3.0Gbps.

			* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
			  udma[/][16,25,33,44,66,100,133] notation is also
			  allowed.

			* [no]ncq: Turn on or off NCQ.

			* [no]ncqtrim: Turn off queued DSM TRIM.

			* nohrst, nosrst, norst: suppress hard, soft
			  and both resets.

			* rstonce: only attempt one reset during
			  hot-unplug link recovery

			* dump_id: dump IDENTIFY data.

			* atapi_dmadir: Enable ATAPI DMADIR bridge support

			* disable: Disable this device.

			If there are multiple matching configurations changing
			the same attribute, the last one is used.

	memblock=debug	[KNL] Enable memblock debug messages.

	load_ramdisk=	[RAM] [Deprecated]

	lockd.nlm_grace_period=P  [NFS] Assign grace period.
			Format: <integer>

	lockd.nlm_tcpport=N	[NFS] Assign TCP port.
			Format: <integer>

	lockd.nlm_timeout=T	[NFS] Assign timeout value.
			Format: <integer>

	lockd.nlm_udpport=M	[NFS] Assign UDP port.
			Format: <integer>

	lockdown=	[SECURITY]
			{ integrity | confidentiality }
			Enable the kernel lockdown feature. If set to
			integrity, kernel features that allow userland to
			modify the running kernel are disabled. If set to
			confidentiality, kernel features that allow userland
			to extract confidential information from the kernel
			are also disabled.

	locktorture.nreaders_stress= [KNL]
			Set the number of locking read-acquisition kthreads.
			Defaults to being automatically set based on the
			number of online CPUs.

	locktorture.nwriters_stress= [KNL]
			Set the number of locking write-acquisition kthreads.

	locktorture.onoff_holdoff= [KNL]
			Set time (s) after boot for CPU-hotplug testing.

	locktorture.onoff_interval= [KNL]
			Set time (s) between CPU-hotplug operations, or
			zero to disable CPU-hotplug testing.

	locktorture.shuffle_interval= [KNL]
			Set task-shuffle interval (jiffies).  Shuffling
			tasks allows some CPUs to go into dyntick-idle
			mode during the locktorture test.

	locktorture.shutdown_secs= [KNL]
			Set time (s) after boot system shutdown.  This
			is useful for hands-off automated testing.

	locktorture.stat_interval= [KNL]
			Time (s) between statistics printk()s.

	locktorture.stutter= [KNL]
			Time (s) to stutter testing, for example,
			specifying five seconds causes the test to run for
			five seconds, wait for five seconds, and so on.
			This tests the locking primitive's ability to
			transition abruptly to and from idle.

	locktorture.torture_type= [KNL]
			Specify the locking implementation to test.

	locktorture.verbose= [KNL]
			Enable additional printk() statements.

	logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
			Format: <irq>

	loglevel=	All Kernel Messages with a loglevel smaller than the
			console loglevel will be printed to the console. It can
			also be changed with klogd or other programs. The
			loglevels are defined as follows:

			0 (KERN_EMERG)		system is unusable
			1 (KERN_ALERT)		action must be taken immediately
			2 (KERN_CRIT)		critical conditions
			3 (KERN_ERR)		error conditions
			4 (KERN_WARNING)	warning conditions
			5 (KERN_NOTICE)		normal but significant condition
			6 (KERN_INFO)		informational
			7 (KERN_DEBUG)		debug-level messages

	log_buf_len=n[KMG]	Sets the size of the printk ring buffer,
			in bytes.  n must be a power of two and greater
			than the minimal size. The minimal size is defined
			by LOG_BUF_SHIFT kernel config parameter. There is
			also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
			that allows to increase the default size depending on
			the number of CPUs. See init/Kconfig for more details.

	logo.nologo	[FB] Disables display of the built-in Linux logo.
			This may be used to provide more screen space for
			kernel log messages and is useful when debugging
			kernel boot problems.

	lp=0		[LP]	Specify parallel ports to use, e.g,
	lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
	lp=reset		first parallel port). 'lp=0' disables the
	lp=auto			printer driver. 'lp=reset' (which can be
				specified in addition to the ports) causes
				attached printers to be reset. Using
				lp=port1,port2,... specifies the parallel ports
				to associate lp devices with, starting with
				lp0. A port specification may be 'none' to skip
				that lp device, or a parport name such as
				'parport0'. Specifying 'lp=auto' instead of a
				port specification list means that device IDs
				from each port should be examined, to see if
				an IEEE 1284-compliant printer is attached; if
				so, the driver will manage that printer.
				See also header of drivers/char/lp.c.

	lpj=n		[KNL]
			Sets loops_per_jiffy to given constant, thus avoiding
			time-consuming boot-time autodetection (up to 250 ms per
			CPU). 0 enables autodetection (default). To determine
			the correct value for your kernel, boot with normal
			autodetection and see what value is printed. Note that
			on SMP systems the preset will be applied to all CPUs,
			which is likely to cause problems if your CPUs need
			significantly divergent settings. An incorrect value
			will cause delays in the kernel to be wrong, leading to
			unpredictable I/O errors and other breakage. Although
			unlikely, in the extreme case this might damage your
			hardware.

	ltpc=		[NET]
			Format: <io>,<irq>,<dma>

	lsm.debug	[SECURITY] Enable LSM initialization debugging output.

	lsm=lsm1,...,lsmN
			[SECURITY] Choose order of LSM initialization. This
			overrides CONFIG_LSM, and the "security=" parameter.

	machvec=	[IA-64] Force the use of a particular machine-vector
			(machvec) in a generic kernel.
			Example: machvec=hpzx1

	machtype=	[Loongson] Share the same kernel image file between
			different yeeloong laptops.
			Example: machtype=lemote-yeeloong-2f-7inch

	max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater
			than or equal to this physical address is ignored.

	maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
			will bring up during bootup.  maxcpus=n : n >= 0 limits
			the kernel to bring up 'n' processors. Surely after
			bootup you can bring up the other plugged cpu by executing
			"echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus
			only takes effect during system bootup.
			While n=0 is a special case, it is equivalent to "nosmp",
			which also disables the IO APIC.

	max_loop=	[LOOP] The number of loop block devices that get
	(loop.max_loop)	unconditionally pre-created at init time. The default
			number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
			of statically allocating a predefined number, loop
			devices can be requested on-demand with the
			/dev/loop-control interface.

	mce		[X86-32] Machine Check Exception

	mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.rst

	md=		[HW] RAID subsystems devices and level
			See Documentation/admin-guide/md.rst.

	mdacon=		[MDA]
			Format: <first>,<last>
			Specifies range of consoles to be captured by the MDA.

	mds=		[X86,INTEL]
			Control mitigation for the Micro-architectural Data
			Sampling (MDS) vulnerability.

			Certain CPUs are vulnerable to an exploit against CPU
			internal buffers which can forward information to a
			disclosure gadget under certain conditions.

			In vulnerable processors, the speculatively
			forwarded data can be used in a cache side channel
			attack, to access data to which the attacker does
			not have direct access.

			This parameter controls the MDS mitigation. The
			options are:

			full       - Enable MDS mitigation on vulnerable CPUs
			full,nosmt - Enable MDS mitigation and disable
				     SMT on vulnerable CPUs
			off        - Unconditionally disable MDS mitigation

			On TAA-affected machines, mds=off can be prevented by
			an active TAA mitigation as both vulnerabilities are
			mitigated with the same mechanism so in order to disable
			this mitigation, you need to specify tsx_async_abort=off
			too.

			Not specifying this option is equivalent to
			mds=full.

			For details see: Documentation/admin-guide/hw-vuln/mds.rst

	mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
			Amount of memory to be used in cases as follows:

			1 for test;
			2 when the kernel is not able to see the whole system memory;
			3 memory that lies after 'mem=' boundary is excluded from
			 the hypervisor, then assigned to KVM guests.

			[X86] Work as limiting max address. Use together
			with memmap= to avoid physical address space collisions.
			Without memmap= PCI devices could be placed at addresses
			belonging to unused RAM.

			Note that this only takes effects during boot time since
			in above case 3, memory may need be hot added after boot
			if system memory of hypervisor is not sufficient.

	mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
			memory.

	memchunk=nn[KMG]
			[KNL,SH] Allow user to override the default size for
			per-device physically contiguous DMA buffers.

	memhp_default_state=online/offline
			[KNL] Set the initial state for the memory hotplug
			onlining policy. If not specified, the default value is
			set according to the
			CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
			option.
			See Documentation/admin-guide/mm/memory-hotplug.rst.

	memmap=exactmap	[KNL,X86] Enable setting of an exact
			E820 memory map, as specified by the user.
			Such memmap=exactmap lines can be constructed based on
			BIOS output or other requirements. See the memmap=nn@ss
			option description.

	memmap=nn[KMG]@ss[KMG]
			[KNL] Force usage of a specific region of memory.
			Region of memory to be used is from ss to ss+nn.
			If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG],
			which limits max address to nn[KMG].
			Multiple different regions can be specified,
			comma delimited.
			Example:
				memmap=100M@2G,100M#3G,1G!1024G

	memmap=nn[KMG]#ss[KMG]
			[KNL,ACPI] Mark specific memory as ACPI data.
			Region of memory to be marked is from ss to ss+nn.

	memmap=nn[KMG]$ss[KMG]
			[KNL,ACPI] Mark specific memory as reserved.
			Region of memory to be reserved is from ss to ss+nn.
			Example: Exclude memory from 0x18690000-0x1869ffff
			         memmap=64K$0x18690000
			         or
			         memmap=0x10000$0x18690000
			Some bootloaders may need an escape character before '$',
			like Grub2, otherwise '$' and the following number
			will be eaten.

	memmap=nn[KMG]!ss[KMG]
			[KNL,X86] Mark specific memory as protected.
			Region of memory to be used, from ss to ss+nn.
			The memory region may be marked as e820 type 12 (0xc)
			and is NVDIMM or ADR memory.

	memmap=<size>%<offset>-<oldtype>+<newtype>
			[KNL,ACPI] Convert memory within the specified region
			from <oldtype> to <newtype>. If "-<oldtype>" is left
			out, the whole region will be marked as <newtype>,
			even if previously unavailable. If "+<newtype>" is left
			out, matching memory will be removed. Types are
			specified as e820 types, e.g., 1 = RAM, 2 = reserved,
			3 = ACPI, 12 = PRAM.

	memory_corruption_check=0/1 [X86]
			Some BIOSes seem to corrupt the first 64k of
			memory when doing things like suspend/resume.
			Setting this option will scan the memory
			looking for corruption.  Enabling this will
			both detect corruption and prevent the kernel
			from using the memory being corrupted.
			However, its intended as a diagnostic tool; if
			repeatable BIOS-originated corruption always
			affects the same memory, you can use memmap=
			to prevent the kernel from using that memory.

	memory_corruption_check_size=size [X86]
			By default it checks for corruption in the low
			64k, making this memory unavailable for normal
			use.  Use this parameter to scan for
			corruption in more or less memory.

	memory_corruption_check_period=seconds [X86]
			By default it checks for corruption every 60
			seconds.  Use this parameter to check at some
			other rate.  0 disables periodic checking.

	memtest=	[KNL,X86,ARM,PPC] Enable memtest
			Format: <integer>
			default : 0 <disable>
			Specifies the number of memtest passes to be
			performed. Each pass selects another test
			pattern from a given set of patterns. Memtest
			fills the memory with this pattern, validates
			memory contents and reserves bad memory
			regions that are detected.

	mem_encrypt=	[X86-64] AMD Secure Memory Encryption (SME) control
			Valid arguments: on, off
			Default (depends on kernel configuration option):
			  on  (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y)
			  off (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n)
			mem_encrypt=on:		Activate SME
			mem_encrypt=off:	Do not activate SME

			Refer to Documentation/virt/kvm/amd-memory-encryption.rst
			for details on when memory encryption can be activated.

	mem_sleep_default=	[SUSPEND] Default system suspend mode:
			s2idle  - Suspend-To-Idle
			shallow - Power-On Suspend or equivalent (if supported)
			deep    - Suspend-To-RAM or equivalent (if supported)
			See Documentation/admin-guide/pm/sleep-states.rst.

	meye.*=		[HW] Set MotionEye Camera parameters
			See Documentation/admin-guide/media/meye.rst.

	mfgpt_irq=	[IA-32] Specify the IRQ to use for the
			Multi-Function General Purpose Timers on AMD Geode
			platforms.

	mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
			the BIOS has incorrectly applied a workaround. TinyBIOS
			version 0.98 is known to be affected, 0.99 fixes the
			problem by letting the user disable the workaround.

	mga=		[HW,DRM]

	min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this
			physical address is ignored.

	mini2440=	[ARM,HW,KNL]
			Format:[0..2][b][c][t]
			Default: "0tb"
			MINI2440 configuration specification:
			0 - The attached screen is the 3.5" TFT
			1 - The attached screen is the 7" TFT
			2 - The VGA Shield is attached (1024x768)
			Leaving out the screen size parameter will not load
			the TFT driver, and the framebuffer will be left
			unconfigured.
			b - Enable backlight. The TFT backlight pin will be
			linked to the kernel VESA blanking code and a GPIO
			LED. This parameter is not necessary when using the
			VGA shield.
			c - Enable the s3c camera interface.
			t - Reserved for enabling touchscreen support. The
			touchscreen support is not enabled in the mainstream
			kernel as of 2.6.30, a preliminary port can be found
			in the "bleeding edge" mini2440 support kernel at
			https://repo.or.cz/w/linux-2.6/mini2440.git

	mitigations=
			[X86,PPC,S390,ARM64] Control optional mitigations for
			CPU vulnerabilities.  This is a set of curated,
			arch-independent options, each of which is an
			aggregation of existing arch-specific options.

			off
				Disable all optional CPU mitigations.  This
				improves system performance, but it may also
				expose users to several CPU vulnerabilities.
				Equivalent to: nopti [X86,PPC]
					       kpti=0 [ARM64]
					       nospectre_v1 [X86,PPC]
					       nobp=0 [S390]
					       nospectre_v2 [X86,PPC,S390,ARM64]
					       spectre_v2_user=off [X86]
					       spec_store_bypass_disable=off [X86,PPC]
					       ssbd=force-off [ARM64]
					       l1tf=off [X86]
					       mds=off [X86]
					       tsx_async_abort=off [X86]
					       kvm.nx_huge_pages=off [X86]

				Exceptions:
					       This does not have any effect on
					       kvm.nx_huge_pages when
					       kvm.nx_huge_pages=force.

			auto (default)
				Mitigate all CPU vulnerabilities, but leave SMT
				enabled, even if it's vulnerable.  This is for
				users who don't want to be surprised by SMT
				getting disabled across kernel upgrades, or who
				have other ways of avoiding SMT-based attacks.
				Equivalent to: (default behavior)

			auto,nosmt
				Mitigate all CPU vulnerabilities, disabling SMT
				if needed.  This is for users who always want to
				be fully mitigated, even if it means losing SMT.
				Equivalent to: l1tf=flush,nosmt [X86]
					       mds=full,nosmt [X86]
					       tsx_async_abort=full,nosmt [X86]

	mminit_loglevel=
			[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
			parameter allows control of the logging verbosity for
			the additional memory initialisation checks. A value
			of 0 disables mminit logging and a level of 4 will
			log everything. Information is printed at KERN_DEBUG
			so loglevel=8 may also need to be specified.

	module.sig_enforce
			[KNL] When CONFIG_MODULE_SIG is set, this means that
			modules without (valid) signatures will fail to load.
			Note that if CONFIG_MODULE_SIG_FORCE is set, that
			is always true, so this option does nothing.

	module_blacklist=  [KNL] Do not load a comma-separated list of
			modules.  Useful for debugging problem modules.

	mousedev.tap_time=
			[MOUSE] Maximum time between finger touching and
			leaving touchpad surface for touch to be considered
			a tap and be reported as a left button click (for
			touchpads working in absolute mode only).
			Format: <msecs>
	mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
			reporting absolute coordinates, such as tablets
	mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
			reporting absolute coordinates, such as tablets

	movablecore=	[KNL,X86,IA-64,PPC]
			Format: nn[KMGTPE] | nn%
			This parameter is the complement to kernelcore=, it
			specifies the amount of memory used for migratable
			allocations.  If both kernelcore and movablecore is
			specified, then kernelcore will be at *least* the
			specified value but may be more.  If movablecore on its
			own is specified, the administrator must be careful
			that the amount of memory usable for all allocations
			is not too small.

	movable_node	[KNL] Boot-time switch to make hotplugable memory
			NUMA nodes to be movable. This means that the memory
			of such nodes will be usable only for movable
			allocations which rules out almost all kernel
			allocations. Use with caution!

	MTD_Partition=	[MTD]
			Format: <name>,<region-number>,<size>,<offset>

	MTD_Region=	[MTD] Format:
			<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]

	mtdparts=	[MTD]
			See drivers/mtd/parsers/cmdlinepart.c

	multitce=off	[PPC]  This parameter disables the use of the pSeries
			firmware feature for updating multiple TCE entries
			at a time.

	onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration

			Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]

			boundary - index of last SLC block on Flex-OneNAND.
				   The remaining blocks are configured as MLC blocks.
			lock	 - Configure if Flex-OneNAND boundary should be locked.
				   Once locked, the boundary cannot be changed.
				   1 indicates lock status, 0 indicates unlock status.

	mtdset=		[ARM]
			ARM/S3C2412 JIVE boot control

			See arch/arm/mach-s3c2412/mach-jive.c

	mtouchusb.raw_coordinates=
			[HW] Make the MicroTouch USB driver use raw coordinates
			('y', default) or cooked coordinates ('n')

	mtrr_chunk_size=nn[KMG] [X86]
			used for mtrr cleanup. It is largest continuous chunk
			that could hold holes aka. UC entries.

	mtrr_gran_size=nn[KMG] [X86]
			Used for mtrr cleanup. It is granularity of mtrr block.
			Default is 1.
			Large value could prevent small alignment from
			using up MTRRs.

	mtrr_spare_reg_nr=n [X86]
			Format: <integer>
			Range: 0,7 : spare reg number
			Default : 1
			Used for mtrr cleanup. It is spare mtrr entries number.
			Set to 2 or more if your graphical card needs more.

	n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card

	netdev=		[NET] Network devices parameters
			Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
			Note that mem_start is often overloaded to mean
			something different and driver-specific.
			This usage is only documented in each driver source
			file if at all.

	nf_conntrack.acct=
			[NETFILTER] Enable connection tracking flow accounting
			0 to disable accounting
			1 to enable accounting
			Default value is 0.

	nfsaddrs=	[NFS] Deprecated.  Use ip= instead.
			See Documentation/admin-guide/nfs/nfsroot.rst.

	nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
			See Documentation/admin-guide/nfs/nfsroot.rst.

	nfsrootdebug	[NFS] enable nfsroot debugging messages.
			See Documentation/admin-guide/nfs/nfsroot.rst.

	nfs.callback_nr_threads=
			[NFSv4] set the total number of threads that the
			NFS client will assign to service NFSv4 callback
			requests.

	nfs.callback_tcpport=
			[NFS] set the TCP port on which the NFSv4 callback
			channel should listen.

	nfs.cache_getent=
			[NFS] sets the pathname to the program which is used
			to update the NFS client cache entries.

	nfs.cache_getent_timeout=
			[NFS] sets the timeout after which an attempt to
			update a cache entry is deemed to have failed.

	nfs.idmap_cache_timeout=
			[NFS] set the maximum lifetime for idmapper cache
			entries.

	nfs.enable_ino64=
			[NFS] enable 64-bit inode numbers.
			If zero, the NFS client will fake up a 32-bit inode
			number for the readdir() and stat() syscalls instead
			of returning the full 64-bit number.
			The default is to return 64-bit inode numbers.

	nfs.max_session_cb_slots=
			[NFSv4.1] Sets the maximum number of session
			slots the client will assign to the callback
			channel. This determines the maximum number of
			callbacks the client will process in parallel for
			a particular server.

	nfs.max_session_slots=
			[NFSv4.1] Sets the maximum number of session slots
			the client will attempt to negotiate with the server.
			This limits the number of simultaneous RPC requests
			that the client can send to the NFSv4.1 server.
			Note that there is little point in setting this
			value higher than the max_tcp_slot_table_limit.

	nfs.nfs4_disable_idmapping=
			[NFSv4] When set to the default of '1', this option
			ensures that both the RPC level authentication
			scheme and the NFS level operations agree to use
			numeric uids/gids if the mount is using the
			'sec=sys' security flavour. In effect it is
			disabling idmapping, which can make migration from
			legacy NFSv2/v3 systems to NFSv4 easier.
			Servers that do not support this mode of operation
			will be autodetected by the client, and it will fall
			back to using the idmapper.
			To turn off this behaviour, set the value to '0'.
	nfs.nfs4_unique_id=
			[NFS4] Specify an additional fixed unique ident-
			ification string that NFSv4 clients can insert into
			their nfs_client_id4 string.  This is typically a
			UUID that is generated at system install time.

	nfs.send_implementation_id =
			[NFSv4.1] Send client implementation identification
			information in exchange_id requests.
			If zero, no implementation identification information
			will be sent.
			The default is to send the implementation identification
			information.

	nfs.recover_lost_locks =
			[NFSv4] Attempt to recover locks that were lost due
			to a lease timeout on the server. Please note that
			doing this risks data corruption, since there are
			no guarantees that the file will remain unchanged
			after the locks are lost.
			If you want to enable the kernel legacy behaviour of
			attempting to recover these locks, then set this
			parameter to '1'.
			The default parameter value of '0' causes the kernel
			not to attempt recovery of lost locks.

	nfs4.layoutstats_timer =
			[NFSv4.2] Change the rate at which the kernel sends
			layoutstats to the pNFS metadata server.

			Setting this to value to 0 causes the kernel to use
			whatever value is the default set by the layout
			driver. A non-zero value sets the minimum interval
			in seconds between layoutstats transmissions.

	nfsd.nfs4_disable_idmapping=
			[NFSv4] When set to the default of '1', the NFSv4
			server will return only numeric uids and gids to
			clients using auth_sys, and will accept numeric uids
			and gids from such clients.  This is intended to ease
			migration from NFSv2/v3.

	nmi_backtrace.backtrace_idle [KNL]
			Dump stacks even of idle CPUs in response to an
			NMI stack-backtrace request.

	nmi_debug=	[KNL,SH] Specify one or more actions to take
			when a NMI is triggered.
			Format: [state][,regs][,debounce][,die]

	nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels
			Format: [panic,][nopanic,][num]
			Valid num: 0 or 1
			0 - turn hardlockup detector in nmi_watchdog off
			1 - turn hardlockup detector in nmi_watchdog on
			When panic is specified, panic when an NMI watchdog
			timeout occurs (or 'nopanic' to not panic on an NMI
			watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set)
			To disable both hard and soft lockup detectors,
			please see 'nowatchdog'.
			This is useful when you use a panic=... timeout and
			need the box quickly up again.

			These settings can be accessed at runtime via
			the nmi_watchdog and hardlockup_panic sysctls.

	netpoll.carrier_timeout=
			[NET] Specifies amount of time (in seconds) that
			netpoll should wait for a carrier. By default netpoll
			waits 4 seconds.

	no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
			emulation library even if a 387 maths coprocessor
			is present.

	no5lvl		[X86-64] Disable 5-level paging mode. Forces
			kernel to use 4-level paging instead.

	nofsgsbase	[X86] Disables FSGSBASE instructions.

	no_console_suspend
			[HW] Never suspend the console
			Disable suspending of consoles during suspend and
			hibernate operations.  Once disabled, debugging
			messages can reach various consoles while the rest
			of the system is being put to sleep (ie, while
			debugging driver suspend/resume hooks).  This may
			not work reliably with all consoles, but is known
			to work with serial and VGA consoles.
			To facilitate more flexible debugging, we also add
			console_suspend, a printk module parameter to control
			it. Users could use console_suspend (usually
			/sys/module/printk/parameters/console_suspend) to
			turn on/off it dynamically.

	novmcoredd	[KNL,KDUMP]
			Disable device dump. Device dump allows drivers to
			append dump data to vmcore so you can collect driver
			specified debug info.  Drivers can append the data
			without any limit and this data is stored in memory,
			so this may cause significant memory stress.  Disabling
			device dump can help save memory but the driver debug
			data will be no longer available.  This parameter
			is only available when CONFIG_PROC_VMCORE_DEVICE_DUMP
			is set.

	noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
			caches in the slab allocator.  Saves per-node memory,
			but will impact performance.

	noalign		[KNL,ARM]

	noaltinstr	[S390] Disables alternative instructions patching
			(CPU alternatives feature).

	noapic		[SMP,APIC] Tells the kernel to not make use of any
			IOAPICs that may be present in the system.

	noautogroup	Disable scheduler automatic task group creation.

	nobats		[PPC] Do not use BATs for mapping kernel lowmem
			on "Classic" PPC cores.

	nocache		[ARM]

	noclflush	[BUGS=X86] Don't use the CLFLUSH instruction

	nodelayacct	[KNL] Disable per-task delay accounting

	nodsp		[SH] Disable hardware DSP at boot time.

	noefi		Disable EFI runtime services support.

	noexec		[IA-64]

	noexec		[X86]
			On X86-32 available only on PAE configured kernels.
			noexec=on: enable non-executable mappings (default)
			noexec=off: disable non-executable mappings

	nosmap		[X86,PPC]
			Disable SMAP (Supervisor Mode Access Prevention)
			even if it is supported by processor.

	nosmep		[X86,PPC]
			Disable SMEP (Supervisor Mode Execution Prevention)
			even if it is supported by processor.

	noexec32	[X86-64]
			This affects only 32-bit executables.
			noexec32=on: enable non-executable mappings (default)
				read doesn't imply executable mappings
			noexec32=off: disable non-executable mappings
				read implies executable mappings

	nofpu		[MIPS,SH] Disable hardware FPU at boot time.

	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
			register save and restore. The kernel will only save
			legacy floating-point registers on task switch.

	nohugeiomap	[KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.

	nosmt		[KNL,S390] Disable symmetric multithreading (SMT).
			Equivalent to smt=1.

			[KNL,X86] Disable symmetric multithreading (SMT).
			nosmt=force: Force disable SMT, cannot be undone
				     via the sysfs control file.

	nospectre_v1	[X86,PPC] Disable mitigations for Spectre Variant 1
			(bounds check bypass). With this option data leaks are
			possible in the system.

	nospectre_v2	[X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for
			the Spectre variant 2 (indirect branch prediction)
			vulnerability. System may allow data leaks with this
			option.

	nospec_store_bypass_disable
			[HW] Disable all mitigations for the Speculative Store Bypass vulnerability

	noxsave		[BUGS=X86] Disables x86 extended register state save
			and restore using xsave. The kernel will fallback to
			enabling legacy floating-point and sse state.

	noxsaveopt	[X86] Disables xsaveopt used in saving x86 extended
			register states. The kernel will fall back to use
			xsave to save the states. By using this parameter,
			performance of saving the states is degraded because
			xsave doesn't support modified optimization while
			xsaveopt supports it on xsaveopt enabled systems.

	noxsaves	[X86] Disables xsaves and xrstors used in saving and
			restoring x86 extended register state in compacted
			form of xsave area. The kernel will fall back to use
			xsaveopt and xrstor to save and restore the states
			in standard form of xsave area. By using this
			parameter, xsave area per process might occupy more
			memory on xsaves enabled systems.

	nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
			wfi(ARM) instruction doesn't work correctly and not to
			use it. This is also useful when using JTAG debugger.

	no_file_caps	Tells the kernel not to honor file capabilities.  The
			only way then for a file to be executed with privilege
			is to be setuid root or executed by root.

	nohalt		[IA-64] Tells the kernel not to use the power saving
			function PAL_HALT_LIGHT when idle. This increases
			power-consumption. On the positive side, it reduces
			interrupt wake-up latency, which may improve performance
			in certain environments such as networked servers or
			real-time systems.

	nohibernate	[HIBERNATION] Disable hibernation and resume.

	nohz=		[KNL] Boottime enable/disable dynamic ticks
			Valid arguments: on, off
			Default: on

	nohz_full=	[KNL,BOOT,SMP,ISOL]
			The argument is a cpu list, as described above.
			In kernels built with CONFIG_NO_HZ_FULL=y, set
			the specified list of CPUs whose tick will be stopped
			whenever possible. The boot CPU will be forced outside
			the range to maintain the timekeeping.  Any CPUs
			in this list will have their RCU callbacks offloaded,
			just as if they had also been called out in the
			rcu_nocbs= boot parameter.

	noiotrap	[SH] Disables trapped I/O port accesses.

	noirqdebug	[X86-32] Disables the code which attempts to detect and
			disable unhandled interrupt sources.

	no_timer_check	[X86,APIC] Disables the code which tests for
			broken timer IRQ sources.

	noisapnp	[ISAPNP] Disables ISA PnP code.

	noinitrd	[RAM] Tells the kernel not to load any configured
			initial RAM disk.

	nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt
			remapping.
			[Deprecated - use intremap=off]

	nointroute	[IA-64]

	noinvpcid	[X86] Disable the INVPCID cpu feature.

	nojitter	[IA-64] Disables jitter checking for ITC timers.

	no-kvmclock	[X86,KVM] Disable paravirtualized KVM clock driver

	no-kvmapf	[X86,KVM] Disable paravirtualized asynchronous page
			fault handling.

	no-vmw-sched-clock
			[X86,PV_OPS] Disable paravirtualized VMware scheduler
			clock and use the default one.

	no-steal-acc	[X86,PV_OPS,ARM64] Disable paravirtualized steal time
			accounting. steal time is computed, but won't
			influence scheduler behaviour

	nolapic		[X86-32,APIC] Do not enable or use the local APIC.

	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.

	noltlbs		[PPC] Do not use large page/tlb entries for kernel
			lowmem mapping on PPC40x and PPC8xx

	nomca		[IA-64] Disable machine check abort handling

	nomce		[X86-32] Disable Machine Check Exception

	nomfgpt		[X86-32] Disable Multi-Function General Purpose
			Timer usage (for AMD Geode machines).

	nonmi_ipi	[X86] Disable using NMI IPIs during panic/reboot to
			shutdown the other cpus.  Instead use the REBOOT_VECTOR
			irq.

	nomodule	Disable module load

	nopat		[X86] Disable PAT (page attribute table extension of
			pagetables) support.

	nopcid		[X86-64] Disable the PCID cpu feature.

	norandmaps	Don't use address space randomization.  Equivalent to
			echo 0 > /proc/sys/kernel/randomize_va_space

	noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
			with UP alternatives

	nordrand	[X86] Disable kernel use of the RDRAND and
			RDSEED instructions even if they are supported
			by the processor.  RDRAND and RDSEED are still
			available to user space applications.

	noresume	[SWSUSP] Disables resume and restores original swap
			space.

	no-scroll	[VGA] Disables scrollback.
			This is required for the Braillex ib80-piezo Braille
			reader made by F.H. Papenmeier (Germany).

	nosbagart	[IA-64]

	nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.

	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
			and disable the IO APIC.  legacy for "maxcpus=0".

	nosoftlockup	[KNL] Disable the soft-lockup detector.

	nosync		[HW,M68K] Disables sync negotiation for all devices.

	nowatchdog	[KNL] Disable both lockup detectors, i.e.
			soft-lockup and NMI watchdog (hard-lockup).

	nowb		[ARM]

	nox2apic	[X86-64,APIC] Do not enable x2APIC mode.

	cpu0_hotplug	[X86] Turn on CPU0 hotplug feature when
			CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
			Some features depend on CPU0. Known dependencies are:
			1. Resume from suspend/hibernate depends on CPU0.
			Suspend/hibernate will fail if CPU0 is offline and you
			need to online CPU0 before suspend/hibernate.
			2. PIC interrupts also depend on CPU0. CPU0 can't be
			removed if a PIC interrupt is detected.
			It's said poweroff/reboot may depend on CPU0 on some
			machines although I haven't seen such issues so far
			after CPU0 is offline on a few tested machines.
			If the dependencies are under your control, you can
			turn on cpu0_hotplug.

	nps_mtm_hs_ctr=	[KNL,ARC]
			This parameter sets the maximum duration, in
			cycles, each HW thread of the CTOP can run
			without interruptions, before HW switches it.
			The actual maximum duration is 16 times this
			parameter's value.
			Format: integer between 1 and 255
			Default: 255

	nptcg=		[IA-64] Override max number of concurrent global TLB
			purges which is reported from either PAL_VM_SUMMARY or
			SAL PALO.

	nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
			could support.  nr_cpus=n : n >= 1 limits the kernel to
			support 'n' processors. It could be larger than the
			number of already plugged CPU during bootup, later in
			runtime you can physically add extra cpu until it reaches
			n. So during boot up some boot time memory for per-cpu
			variables need be pre-allocated for later physical cpu
			hot plugging.

	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.

	numa_balancing=	[KNL,X86] Enable or disable automatic NUMA balancing.
			Allowed values are enable and disable

	numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
			'node', 'default' can be specified
			This can be set from sysctl after boot.
			See Documentation/admin-guide/sysctl/vm.rst for details.

	ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
			See Documentation/core-api/debugging-via-ohci1394.rst for more
			info.

	olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
			Rather than timing out after 20 ms if an EC
			command is not properly ACKed, override the length
			of the timeout.  We have interrupts disabled while
			waiting for the ACK, so if this is set too high
			interrupts *may* be lost!

	omap_mux=	[OMAP] Override bootloader pin multiplexing.
			Format: <mux_mode0.mode_name=value>...
			For example, to override I2C bus2:
			omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100

	oprofile.timer=	[HW]
			Use timer interrupt instead of performance counters

	oprofile.cpu_type=	Force an oprofile cpu type
			This might be useful if you have an older oprofile
			userland or if you want common events.
			Format: { arch_perfmon }
			arch_perfmon: [X86] Force use of architectural
				perfmon on Intel CPUs instead of the
				CPU specific event set.
			timer: [X86] Force use of architectural NMI
				timer mode (see also oprofile.timer
				for generic hr timer mode)

	oops=panic	Always panic on oopses. Default is to just kill the
			process, but there is a small probability of
			deadlocking the machine.
			This will also cause panics on machine check exceptions.
			Useful together with panic=30 to trigger a reboot.

	page_alloc.shuffle=
			[KNL] Boolean flag to control whether the page allocator
			should randomize its free lists. The randomization may
			be automatically enabled if the kernel detects it is
			running on a platform with a direct-mapped memory-side
			cache, and this parameter can be used to
			override/disable that behavior. The state of the flag
			can be read from sysfs at:
			/sys/module/page_alloc/parameters/shuffle.

	page_owner=	[KNL] Boot-time page_owner enabling option.
			Storage of the information about who allocated
			each page is disabled in default. With this switch,
			we can turn it on.
			on: enable the feature

	page_poison=	[KNL] Boot-time parameter changing the state of
			poisoning on the buddy allocator, available with
			CONFIG_PAGE_POISONING=y.
			off: turn off poisoning (default)
			on: turn on poisoning

	panic=		[KNL] Kernel behaviour on panic: delay <timeout>
			timeout > 0: seconds before rebooting
			timeout = 0: wait forever
			timeout < 0: reboot immediately
			Format: <timeout>

	panic_print=	Bitmask for printing system info when panic happens.
			User can chose combination of the following bits:
			bit 0: print all tasks info
			bit 1: print system memory info
			bit 2: print timer info
			bit 3: print locks info if CONFIG_LOCKDEP is on
			bit 4: print ftrace buffer
			bit 5: print all printk messages in buffer

	panic_on_taint=	Bitmask for conditionally calling panic() in add_taint()
			Format: <hex>[,nousertaint]
			Hexadecimal bitmask representing the set of TAINT flags
			that will cause the kernel to panic when add_taint() is
			called with any of the flags in this set.
			The optional switch "nousertaint" can be utilized to
			prevent userspace forced crashes by writing to sysctl
			/proc/sys/kernel/tainted any flagset matching with the
			bitmask set on panic_on_taint.
			See Documentation/admin-guide/tainted-kernels.rst for
			extra details on the taint flags that users can pick
			to compose the bitmask to assign to panic_on_taint.

	panic_on_warn	panic() instead of WARN().  Useful to cause kdump
			on a WARN().

	crash_kexec_post_notifiers
			Run kdump after running panic-notifiers and dumping
			kmsg. This only for the users who doubt kdump always
			succeeds in any situation.
			Note that this also increases risks of kdump failure,
			because some panic notifiers can make the crashed
			kernel more unstable.

	parkbd.port=	[HW] Parallel port number the keyboard adapter is
			connected to, default is 0.
			Format: <parport#>
	parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
			0 for XT, 1 for AT (default is AT).
			Format: <mode>

	parport=	[HW,PPT] Specify parallel ports. 0 disables.
			Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
			Use 'auto' to force the driver to use any
			IRQ/DMA settings detected (the default is to
			ignore detected IRQ/DMA settings because of
			possible conflicts). You can specify the base
			address, IRQ, and DMA settings; IRQ and DMA
			should be numbers, or 'auto' (for using detected
			settings on that particular port), or 'nofifo'
			(to avoid using a FIFO even if it is detected).
			Parallel ports are assigned in the order they
			are specified on the command line, starting
			with parport0.

	parport_init_mode=	[HW,PPT]
			Configure VIA parallel port to operate in
			a specific mode. This is necessary on Pegasos
			computer where firmware has no options for setting
			up parallel port mode and sets it to spp.
			Currently this function knows 686a and 8231 chips.
			Format: [spp|ps2|epp|ecp|ecpepp]

	pause_on_oops=
			Halt all CPUs after the first oops has been printed for
			the specified number of seconds.  This is to be used if
			your oopses keep scrolling off the screen.

	pcbit=		[HW,ISDN]

	pcd.		[PARIDE]
			See header of drivers/block/paride/pcd.c.
			See also Documentation/admin-guide/blockdev/paride.rst.

	pci=option[,option...]	[PCI] various PCI subsystem options.

				Some options herein operate on a specific device
				or a set of devices (<pci_dev>). These are
				specified in one of the following formats:

				[<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]*
				pci:<vendor>:<device>[:<subvendor>:<subdevice>]

				Note: the first format specifies a PCI
				bus/device/function address which may change
				if new hardware is inserted, if motherboard
				firmware changes, or due to changes caused
				by other kernel parameters. If the
				domain is left unspecified, it is
				taken to be zero. Optionally, a path
				to a device through multiple device/function
				addresses can be specified after the base
				address (this is more robust against
				renumbering issues).  The second format
				selects devices using IDs from the
				configuration space which may match multiple
				devices in the system.

		earlydump	dump PCI config space before the kernel
				changes anything
		off		[X86] don't probe for the PCI bus
		bios		[X86-32] force use of PCI BIOS, don't access
				the hardware directly. Use this if your machine
				has a non-standard PCI host bridge.
		nobios		[X86-32] disallow use of PCI BIOS, only direct
				hardware access methods are allowed. Use this
				if you experience crashes upon bootup and you
				suspect they are caused by the BIOS.
		conf1		[X86] Force use of PCI Configuration Access
				Mechanism 1 (config address in IO port 0xCF8,
				data in IO port 0xCFC, both 32-bit).
		conf2		[X86] Force use of PCI Configuration Access
				Mechanism 2 (IO port 0xCF8 is an 8-bit port for
				the function, IO port 0xCFA, also 8-bit, sets
				bus number. The config space is then accessed
				through ports 0xC000-0xCFFF).
				See http://wiki.osdev.org/PCI for more info
				on the configuration access mechanisms.
		noaer		[PCIE] If the PCIEAER kernel config parameter is
				enabled, this kernel boot option can be used to
				disable the use of PCIE advanced error reporting.
		nodomains	[PCI] Disable support for multiple PCI
				root domains (aka PCI segments, in ACPI-speak).
		nommconf	[X86] Disable use of MMCONFIG for PCI
				Configuration
		check_enable_amd_mmconf [X86] check for and enable
				properly configured MMIO access to PCI
				config space on AMD family 10h CPU
		nomsi		[MSI] If the PCI_MSI kernel config parameter is
				enabled, this kernel boot option can be used to
				disable the use of MSI interrupts system-wide.
		noioapicquirk	[APIC] Disable all boot interrupt quirks.
				Safety option to keep boot IRQs enabled. This
				should never be necessary.
		ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
				primary IO-APIC for bridges that cannot disable
				boot IRQs. This fixes a source of spurious IRQs
				when the system masks IRQs.
		noioapicreroute	[APIC] Disable workaround that uses the
				boot IRQ equivalent of an IRQ that connects to
				a chipset where boot IRQs cannot be disabled.
				The opposite of ioapicreroute.
		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
				routing table. These calls are known to be buggy
				on several machines and they hang the machine
				when used, but on other computers it's the only
				way to get the interrupt routing table. Try
				this option if the kernel is unable to allocate
				IRQs or discover secondary PCI buses on your
				motherboard.
		rom		[X86] Assign address space to expansion ROMs.
				Use with caution as certain devices share
				address decoders between ROMs and other
				resources.
		norom		[X86] Do not assign address space to
				expansion ROMs that do not already have
				BIOS assigned address ranges.
		nobar		[X86] Do not assign address space to the
				BARs that weren't assigned by the BIOS.
		irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
				assigned automatically to PCI devices. You can
				make the kernel exclude IRQs of your ISA cards
				this way.
		pirqaddr=0xAAAAA	[X86] Specify the physical address
				of the PIRQ table (normally generated
				by the BIOS) if it is outside the
				F0000h-100000h range.
		lastbus=N	[X86] Scan all buses thru bus #N. Can be
				useful if the kernel is unable to find your
				secondary buses and you want to tell it
				explicitly which ones they are.
		assign-busses	[X86] Always assign all PCI bus
				numbers ourselves, overriding
				whatever the firmware may have done.
		usepirqmask	[X86] Honor the possible IRQ mask stored
				in the BIOS $PIR table. This is needed on
				some systems with broken BIOSes, notably
				some HP Pavilion N5400 and Omnibook XE3
				notebooks. This will have no effect if ACPI
				IRQ routing is enabled.
		noacpi		[X86] Do not use ACPI for IRQ routing
				or for PCI scanning.
		use_crs		[X86] Use PCI host bridge window information
				from ACPI.  On BIOSes from 2008 or later, this
				is enabled by default.  If you need to use this,
				please report a bug.
		nocrs		[X86] Ignore PCI host bridge windows from ACPI.
				If you need to use this, please report a bug.
		routeirq	Do IRQ routing for all PCI devices.
				This is normally done in pci_enable_device(),
				so this option is a temporary workaround
				for broken drivers that don't call it.
		skip_isa_align	[X86] do not align io start addr, so can
				handle more pci cards
		noearly		[X86] Don't do any early type 1 scanning.
				This might help on some broken boards which
				machine check when some devices' config space
				is read. But various workarounds are disabled
				and some IOMMU drivers will not work.
		bfsort		Sort PCI devices into breadth-first order.
				This sorting is done to get a device
				order compatible with older (<= 2.4) kernels.
		nobfsort	Don't sort PCI devices into breadth-first order.
		pcie_bus_tune_off	Disable PCIe MPS (Max Payload Size)
				tuning and use the BIOS-configured MPS defaults.
		pcie_bus_safe	Set every device's MPS to the largest value
				supported by all devices below the root complex.
		pcie_bus_perf	Set device MPS to the largest allowable MPS
				based on its parent bus. Also set MRRS (Max
				Read Request Size) to the largest supported
				value (no larger than the MPS that the device
				or bus can support) for best performance.
		pcie_bus_peer2peer	Set every device's MPS to 128B, which
				every device is guaranteed to support. This
				configuration allows peer-to-peer DMA between
				any pair of devices, possibly at the cost of
				reduced performance.  This also guarantees
				that hot-added devices will work.
		cbiosize=nn[KMG]	The fixed amount of bus space which is
				reserved for the CardBus bridge's IO window.
				The default value is 256 bytes.
		cbmemsize=nn[KMG]	The fixed amount of bus space which is
				reserved for the CardBus bridge's memory
				window. The default value is 64 megabytes.
		resource_alignment=
				Format:
				[<order of align>@]<pci_dev>[; ...]
				Specifies alignment and device to reassign
				aligned memory resources. How to
				specify the device is described above.
				If <order of align> is not specified,
				PAGE_SIZE is used as alignment.
				A PCI-PCI bridge can be specified if resource
				windows need to be expanded.
				To specify the alignment for several
				instances of a device, the PCI vendor,
				device, subvendor, and subdevice may be
				specified, e.g., 12@pci:8086:9c22:103c:198f
				for 4096-byte alignment.
		ecrc=		Enable/disable PCIe ECRC (transaction layer
				end-to-end CRC checking).
				bios: Use BIOS/firmware settings. This is the
				the default.
				off: Turn ECRC off
				on: Turn ECRC on.
		hpiosize=nn[KMG]	The fixed amount of bus space which is
				reserved for hotplug bridge's IO window.
				Default size is 256 bytes.
		hpmmiosize=nn[KMG]	The fixed amount of bus space which is
				reserved for hotplug bridge's MMIO window.
				Default size is 2 megabytes.
		hpmmioprefsize=nn[KMG]	The fixed amount of bus space which is
				reserved for hotplug bridge's MMIO_PREF window.
				Default size is 2 megabytes.
		hpmemsize=nn[KMG]	The fixed amount of bus space which is
				reserved for hotplug bridge's MMIO and
				MMIO_PREF window.
				Default size is 2 megabytes.
		hpbussize=nn	The minimum amount of additional bus numbers
				reserved for buses below a hotplug bridge.
				Default is 1.
		realloc=	Enable/disable reallocating PCI bridge resources
				if allocations done by BIOS are too small to
				accommodate resources required by all child
				devices.
				off: Turn realloc off
				on: Turn realloc on
		realloc		same as realloc=on
		noari		do not use PCIe ARI.
		noats		[PCIE, Intel-IOMMU, AMD-IOMMU]
				do not use PCIe ATS (and IOMMU device IOTLB).
		pcie_scan_all	Scan all possible PCIe devices.  Otherwise we
				only look for one device below a PCIe downstream
				port.
		big_root_window	Try to add a big 64bit memory window to the PCIe
				root complex on AMD CPUs. Some GFX hardware
				can resize a BAR to allow access to all VRAM.
				Adding the window is slightly risky (it may
				conflict with unreported devices), so this
				taints the kernel.
		disable_acs_redir=<pci_dev>[; ...]
				Specify one or more PCI devices (in the format
				specified above) separated by semicolons.
				Each device specified will have the PCI ACS
				redirect capabilities forced off which will
				allow P2P traffic between devices through
				bridges without forcing it upstream. Note:
				this removes isolation between devices and
				may put more devices in an IOMMU group.
		force_floating	[S390] Force usage of floating interrupts.
		nomio		[S390] Do not use MIO instructions.
		norid		[S390] ignore the RID field and force use of
				one PCI domain per PCI function

	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
			Management.
		off	Disable ASPM.
		force	Enable ASPM even on devices that claim not to support it.
			WARNING: Forcing ASPM on may cause system lockups.

	pcie_ports=	[PCIE] PCIe port services handling:
		native	Use native PCIe services (PME, AER, DPC, PCIe hotplug)
			even if the platform doesn't give the OS permission to
			use them.  This may cause conflicts if the platform
			also tries to use these services.
		dpc-native	Use native PCIe service for DPC only.  May
				cause conflicts if firmware uses AER or DPC.
		compat	Disable native PCIe services (PME, AER, DPC, PCIe
			hotplug).

	pcie_port_pm=	[PCIE] PCIe port power management handling:
		off	Disable power management of all PCIe ports
		force	Forcibly enable power management of all PCIe ports

	pcie_pme=	[PCIE,PM] Native PCIe PME signaling options:
		nomsi	Do not use MSI for native PCIe PME signaling (this makes
			all PCIe root ports use INTx for all services).

	pcmv=		[HW,PCMCIA] BadgePAD 4

	pd_ignore_unused
			[PM]
			Keep all power-domains already enabled by bootloader on,
			even if no driver has claimed them. This is useful
			for debug and development, but should not be
			needed on a platform with proper driver support.

	pd.		[PARIDE]
			See Documentation/admin-guide/blockdev/paride.rst.

	pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
			boot time.
			Format: { 0 | 1 }
			See arch/parisc/kernel/pdc_chassis.c

	percpu_alloc=	Select which percpu first chunk allocator to use.
			Currently supported values are "embed" and "page".
			Archs may support subset or none of the	selections.
			See comments in mm/percpu.c for details on each
			allocator.  This parameter is primarily	for debugging
			and performance comparison.

	pf.		[PARIDE]
			See Documentation/admin-guide/blockdev/paride.rst.

	pg.		[PARIDE]
			See Documentation/admin-guide/blockdev/paride.rst.

	pirq=		[SMP,APIC] Manual mp-table setup
			See Documentation/x86/i386/IO-APIC.rst.

	plip=		[PPT,NET] Parallel port network link
			Format: { parport<nr> | timid | 0 }
			See also Documentation/admin-guide/parport.rst.

	pmtmr=		[X86] Manual setup of pmtmr I/O Port.
			Override pmtimer IOPort with a hex value.
			e.g. pmtmr=0x508

	pm_debug_messages	[SUSPEND,KNL]
			Enable suspend/resume debug messages during boot up.

	pnp.debug=1	[PNP]
			Enable PNP debug messages (depends on the
			CONFIG_PNP_DEBUG_MESSAGES option).  Change at run-time
			via /sys/module/pnp/parameters/debug.  We always show
			current resource usage; turning this on also shows
			possible settings and some assignment information.

	pnpacpi=	[ACPI]
			{ off }

	pnpbios=	[ISAPNP]
			{ on | off | curr | res | no-curr | no-res }

	pnp_reserve_irq=
			[ISAPNP] Exclude IRQs for the autoconfiguration

	pnp_reserve_dma=
			[ISAPNP] Exclude DMAs for the autoconfiguration

	pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
			Ranges are in pairs (I/O port base and size).

	pnp_reserve_mem=
			[ISAPNP] Exclude memory regions for the
			autoconfiguration.
			Ranges are in pairs (memory base and size).

	ports=		[IP_VS_FTP] IPVS ftp helper module
			Default is 21.
			Up to 8 (IP_VS_APP_MAX_PORTS) ports
			may be specified.
			Format: <port>,<port>....

	powersave=off	[PPC] This option disables power saving features.
			It specifically disables cpuidle and sets the
			platform machine description specific power_save
			function to NULL. On Idle the CPU just reduces
			execution priority.

	ppc_strict_facility_enable
			[PPC] This option catches any kernel floating point,
			Altivec, VSX and SPE outside of regions specifically
			allowed (eg kernel_enable_fpu()/kernel_disable_fpu()).
			There is some performance impact when enabling this.

	ppc_tm=		[PPC]
			Format: {"off"}
			Disable Hardware Transactional Memory

	print-fatal-signals=
			[KNL] debug: print fatal signals

			If enabled, warn about various signal handling
			related application anomalies: too many signals,
			too many POSIX.1 timers, fatal signals causing a
			coredump - etc.

			If you hit the warning due to signal overflow,
			you might want to try "ulimit -i unlimited".

			default: off.

	printk.always_kmsg_dump=
			Trigger kmsg_dump for cases other than kernel oops or
			panics
			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
			default: disabled

	printk.devkmsg={on,off,ratelimit}
			Control writing to /dev/kmsg.
			on - unlimited logging to /dev/kmsg from userspace
			off - logging to /dev/kmsg disabled
			ratelimit - ratelimit the logging
			Default: ratelimit

	printk.time=	Show timing data prefixed to each printk message line
			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)

	processor.max_cstate=	[HW,ACPI]
			Limit processor to maximum C-state
			max_cstate=9 overrides any DMI blacklist limit.

	processor.nocst	[HW,ACPI]
			Ignore the _CST method to determine C-states,
			instead using the legacy FADT method

	profile=	[KNL] Enable kernel profiling via /proc/profile
			Format: [<profiletype>,]<number>
			Param: <profiletype>: "schedule", "sleep", or "kvm"
				[defaults to kernel profiling]
			Param: "schedule" - profile schedule points.
			Param: "sleep" - profile D-state sleeping (millisecs).
				Requires CONFIG_SCHEDSTATS
			Param: "kvm" - profile VM exits.
			Param: <number> - step/bucket size as a power of 2 for
				statistical time based profiling.

	prompt_ramdisk=	[RAM] [Deprecated]

	prot_virt=	[S390] enable hosting protected virtual machines
			isolated from the hypervisor (if hardware supports
			that).
			Format: <bool>

	psi=		[KNL] Enable or disable pressure stall information
			tracking.
			Format: <bool>

	psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
			probe for; one of (bare|imps|exps|lifebook|any).
	psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
			per second.
	psmouse.resetafter=	[HW,MOUSE]
			Try to reset the device after so many bad packets
			(0 = never).
	psmouse.resolution=
			[HW,MOUSE] Set desired mouse resolution, in dpi.
	psmouse.smartscroll=
			[HW,MOUSE] Controls Logitech smartscroll autorepeat.
			0 = disabled, 1 = enabled (default).

	pstore.backend=	Specify the name of the pstore backend to use

	pt.		[PARIDE]
			See Documentation/admin-guide/blockdev/paride.rst.

	pti=		[X86-64] Control Page Table Isolation of user and
			kernel address spaces.  Disabling this feature
			removes hardening, but improves performance of
			system calls and interrupts.

			on   - unconditionally enable
			off  - unconditionally disable
			auto - kernel detects whether your CPU model is
			       vulnerable to issues that PTI mitigates

			Not specifying this option is equivalent to pti=auto.

	nopti		[X86-64]
			Equivalent to pti=off

	pty.legacy_count=
			[KNL] Number of legacy pty's. Overwrites compiled-in
			default number.

	quiet		[KNL] Disable most log messages

	r128=		[HW,DRM]

	raid=		[HW,RAID]
			See Documentation/admin-guide/md.rst.

	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
			See Documentation/admin-guide/blockdev/ramdisk.rst.

	ramdisk_start=	[RAM] RAM disk image start address

	random.trust_cpu={on,off}
			[KNL] Enable or disable trusting the use of the
			CPU's random number generator (if available) to
			fully seed the kernel's CRNG. Default is controlled
			by CONFIG_RANDOM_TRUST_CPU.

	ras=option[,option,...]	[KNL] RAS-specific options

		cec_disable	[X86]
				Disable the Correctable Errors Collector,
				see CONFIG_RAS_CEC help text.

	rcu_nocbs=	[KNL]
			The argument is a cpu list, as described above,
			except that the string "all" can be used to
			specify every CPU on the system.

			In kernels built with CONFIG_RCU_NOCB_CPU=y, set
			the specified list of CPUs to be no-callback CPUs.
			Invocation of these CPUs' RCU callbacks will be
			offloaded to "rcuox/N" kthreads created for that
			purpose, where "x" is "p" for RCU-preempt, and
			"s" for RCU-sched, and "N" is the CPU number.
			This reduces OS jitter on the offloaded CPUs,
			which can be useful for HPC and real-time
			workloads.  It can also improve energy efficiency
			for asymmetric multiprocessors.

	rcu_nocb_poll	[KNL]
			Rather than requiring that offloaded CPUs
			(specified by rcu_nocbs= above) explicitly
			awaken the corresponding "rcuoN" kthreads,
			make these kthreads poll for callbacks.
			This improves the real-time response for the
			offloaded CPUs by relieving them of the need to
			wake up the corresponding kthread, but degrades
			energy efficiency by requiring that the kthreads
			periodically wake up to do the polling.

	rcutree.blimit=	[KNL]
			Set maximum number of finished RCU callbacks to
			process in one batch.

	rcutree.dump_tree=	[KNL]
			Dump the structure of the rcu_node combining tree
			out at early boot.  This is used for diagnostic
			purposes, to verify correct tree setup.

	rcutree.gp_cleanup_delay=	[KNL]
			Set the number of jiffies to delay each step of
			RCU grace-period cleanup.

	rcutree.gp_init_delay=	[KNL]
			Set the number of jiffies to delay each step of
			RCU grace-period initialization.

	rcutree.gp_preinit_delay=	[KNL]
			Set the number of jiffies to delay each step of
			RCU grace-period pre-initialization, that is,
			the propagation of recent CPU-hotplug changes up
			the rcu_node combining tree.

	rcutree.use_softirq=	[KNL]
			If set to zero, move all RCU_SOFTIRQ processing to
			per-CPU rcuc kthreads.  Defaults to a non-zero
			value, meaning that RCU_SOFTIRQ is used by default.
			Specify rcutree.use_softirq=0 to use rcuc kthreads.

	rcutree.rcu_fanout_exact= [KNL]
			Disable autobalancing of the rcu_node combining
			tree.  This is used by rcutorture, and might
			possibly be useful for architectures having high
			cache-to-cache transfer latencies.

	rcutree.rcu_fanout_leaf= [KNL]
			Change the number of CPUs assigned to each
			leaf rcu_node structure.  Useful for very
			large systems, which will choose the value 64,
			and for NUMA systems with large remote-access
			latencies, which will choose a value aligned
			with the appropriate hardware boundaries.

	rcutree.rcu_min_cached_objs= [KNL]
			Minimum number of objects which are cached and
			maintained per one CPU. Object size is equal
			to PAGE_SIZE. The cache allows to reduce the
			pressure to page allocator, also it makes the
			whole algorithm to behave better in low memory
			condition.

	rcutree.jiffies_till_first_fqs= [KNL]
			Set delay from grace-period initialization to
			first attempt to force quiescent states.
			Units are jiffies, minimum value is zero,
			and maximum value is HZ.

	rcutree.jiffies_till_next_fqs= [KNL]
			Set delay between subsequent attempts to force
			quiescent states.  Units are jiffies, minimum
			value is one, and maximum value is HZ.

	rcutree.jiffies_till_sched_qs= [KNL]
			Set required age in jiffies for a
			given grace period before RCU starts
			soliciting quiescent-state help from
			rcu_note_context_switch() and cond_resched().
			If not specified, the kernel will calculate
			a value based on the most recent settings
			of rcutree.jiffies_till_first_fqs
			and rcutree.jiffies_till_next_fqs.
			This calculated value may be viewed in
			rcutree.jiffies_to_sched_qs.  Any attempt to set
			rcutree.jiffies_to_sched_qs will be cheerfully
			overwritten.

	rcutree.kthread_prio= 	 [KNL,BOOT]
			Set the SCHED_FIFO priority of the RCU per-CPU
			kthreads (rcuc/N). This value is also used for
			the priority of the RCU boost threads (rcub/N)
			and for the RCU grace-period kthreads (rcu_bh,
			rcu_preempt, and rcu_sched). If RCU_BOOST is
			set, valid values are 1-99 and the default is 1
			(the least-favored priority).  Otherwise, when
			RCU_BOOST is not set, valid values are 0-99 and
			the default is zero (non-realtime operation).

	rcutree.rcu_nocb_gp_stride= [KNL]
			Set the number of NOCB callback kthreads in
			each group, which defaults to the square root
			of the number of CPUs.	Larger numbers reduce
			the wakeup overhead on the global grace-period
			kthread, but increases that same overhead on
			each group's NOCB grace-period kthread.

	rcutree.qhimark= [KNL]
			Set threshold of queued RCU callbacks beyond which
			batch limiting is disabled.

	rcutree.qlowmark= [KNL]
			Set threshold of queued RCU callbacks below which
			batch limiting is re-enabled.

	rcutree.qovld= [KNL]
			Set threshold of queued RCU callbacks beyond which
			RCU's force-quiescent-state scan will aggressively
			enlist help from cond_resched() and sched IPIs to
			help CPUs more quickly reach quiescent states.
			Set to less than zero to make this be set based
			on rcutree.qhimark at boot time and to zero to
			disable more aggressive help enlistment.

	rcutree.rcu_idle_gp_delay= [KNL]
			Set wakeup interval for idle CPUs that have
			RCU callbacks (RCU_FAST_NO_HZ=y).

	rcutree.rcu_idle_lazy_gp_delay= [KNL]
			Set wakeup interval for idle CPUs that have
			only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
			Lazy RCU callbacks are those which RCU can
			prove do nothing more than free memory.

	rcutree.rcu_kick_kthreads= [KNL]
			Cause the grace-period kthread to get an extra
			wake_up() if it sleeps three times longer than
			it should at force-quiescent-state time.
			This wake_up() will be accompanied by a
			WARN_ONCE() splat and an ftrace_dump().

	rcutree.rcu_unlock_delay= [KNL]
			In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels,
			this specifies an rcu_read_unlock()-time delay
			in microseconds.  This defaults to zero.
			Larger delays increase the probability of
			catching RCU pointer leaks, that is, buggy use
			of RCU-protected pointers after the relevant
			rcu_read_unlock() has completed.

	rcutree.sysrq_rcu= [KNL]
			Commandeer a sysrq key to dump out Tree RCU's
			rcu_node tree with an eye towards determining
			why a new grace period has not yet started.

	rcuscale.gp_async= [KNL]
			Measure performance of asynchronous
			grace-period primitives such as call_rcu().

	rcuscale.gp_async_max= [KNL]
			Specify the maximum number of outstanding
			callbacks per writer thread.  When a writer
			thread exceeds this limit, it invokes the
			corresponding flavor of rcu_barrier() to allow
			previously posted callbacks to drain.

	rcuscale.gp_exp= [KNL]
			Measure performance of expedited synchronous
			grace-period primitives.

	rcuscale.holdoff= [KNL]
			Set test-start holdoff period.  The purpose of
			this parameter is to delay the start of the
			test until boot completes in order to avoid
			interference.

	rcuscale.kfree_rcu_test= [KNL]
			Set to measure performance of kfree_rcu() flooding.

	rcuscale.kfree_nthreads= [KNL]
			The number of threads running loops of kfree_rcu().

	rcuscale.kfree_alloc_num= [KNL]
			Number of allocations and frees done in an iteration.

	rcuscale.kfree_loops= [KNL]
			Number of loops doing rcuscale.kfree_alloc_num number
			of allocations and frees.

	rcuscale.nreaders= [KNL]
			Set number of RCU readers.  The value -1 selects
			N, where N is the number of CPUs.  A value
			"n" less than -1 selects N-n+1, where N is again
			the number of CPUs.  For example, -2 selects N
			(the number of CPUs), -3 selects N+1, and so on.
			A value of "n" less than or equal to -N selects
			a single reader.

	rcuscale.nwriters= [KNL]
			Set number of RCU writers.  The values operate
			the same as for rcuscale.nreaders.
			N, where N is the number of CPUs

	rcuscale.perf_type= [KNL]
			Specify the RCU implementation to test.

	rcuscale.shutdown= [KNL]
			Shut the system down after performance tests
			complete.  This is useful for hands-off automated
			testing.

	rcuscale.verbose= [KNL]
			Enable additional printk() statements.

	rcuscale.writer_holdoff= [KNL]
			Write-side holdoff between grace periods,
			in microseconds.  The default of zero says
			no holdoff.

	rcutorture.fqs_duration= [KNL]
			Set duration of force_quiescent_state bursts
			in microseconds.

	rcutorture.fqs_holdoff= [KNL]
			Set holdoff time within force_quiescent_state bursts
			in microseconds.

	rcutorture.fqs_stutter= [KNL]
			Set wait time between force_quiescent_state bursts
			in seconds.

	rcutorture.fwd_progress= [KNL]
			Enable RCU grace-period forward-progress testing
			for the types of RCU supporting this notion.

	rcutorture.fwd_progress_div= [KNL]
			Specify the fraction of a CPU-stall-warning
			period to do tight-loop forward-progress testing.

	rcutorture.fwd_progress_holdoff= [KNL]
			Number of seconds to wait between successive
			forward-progress tests.

	rcutorture.fwd_progress_need_resched= [KNL]
			Enclose cond_resched() calls within checks for
			need_resched() during tight-loop forward-progress
			testing.

	rcutorture.gp_cond= [KNL]
			Use conditional/asynchronous update-side
			primitives, if available.

	rcutorture.gp_exp= [KNL]
			Use expedited update-side primitives, if available.

	rcutorture.gp_normal= [KNL]
			Use normal (non-expedited) asynchronous
			update-side primitives, if available.

	rcutorture.gp_sync= [KNL]
			Use normal (non-expedited) synchronous
			update-side primitives, if available.  If all
			of rcutorture.gp_cond=, rcutorture.gp_exp=,
			rcutorture.gp_normal=, and rcutorture.gp_sync=
			are zero, rcutorture acts as if is interpreted
			they are all non-zero.

	rcutorture.irqreader= [KNL]
			Run RCU readers from irq handlers, or, more
			accurately, from a timer handler.  Not all RCU
			flavors take kindly to this sort of thing.

	rcutorture.leakpointer= [KNL]
			Leak an RCU-protected pointer out of the reader.
			This can of course result in splats, and is
			intended to test the ability of things like
			CONFIG_RCU_STRICT_GRACE_PERIOD=y to detect
			such leaks.

	rcutorture.n_barrier_cbs= [KNL]
			Set callbacks/threads for rcu_barrier() testing.

	rcutorture.nfakewriters= [KNL]
			Set number of concurrent RCU writers.  These just
			stress RCU, they don't participate in the actual
			test, hence the "fake".

	rcutorture.nreaders= [KNL]
			Set number of RCU readers.  The value -1 selects
			N-1, where N is the number of CPUs.  A value
			"n" less than -1 selects N-n-2, where N is again
			the number of CPUs.  For example, -2 selects N
			(the number of CPUs), -3 selects N+1, and so on.

	rcutorture.object_debug= [KNL]
			Enable debug-object double-call_rcu() testing.

	rcutorture.onoff_holdoff= [KNL]
			Set time (s) after boot for CPU-hotplug testing.

	rcutorture.onoff_interval= [KNL]
			Set time (jiffies) between CPU-hotplug operations,
			or zero to disable CPU-hotplug testing.

	rcutorture.read_exit= [KNL]
			Set the number of read-then-exit kthreads used
			to test the interaction of RCU updaters and
			task-exit processing.

	rcutorture.read_exit_burst= [KNL]
			The number of times in a given read-then-exit
			episode that a set of read-then-exit kthreads
			is spawned.

	rcutorture.read_exit_delay= [KNL]
			The delay, in seconds, between successive
			read-then-exit testing episodes.

	rcutorture.shuffle_interval= [KNL]
			Set task-shuffle interval (s).  Shuffling tasks
			allows some CPUs to go into dyntick-idle mode
			during the rcutorture test.

	rcutorture.shutdown_secs= [KNL]
			Set time (s) after boot system shutdown.  This
			is useful for hands-off automated testing.

	rcutorture.stall_cpu= [KNL]
			Duration of CPU stall (s) to test RCU CPU stall
			warnings, zero to disable.

	rcutorture.stall_cpu_block= [KNL]
			Sleep while stalling if set.  This will result
			in warnings from preemptible RCU in addition
			to any other stall-related activity.

	rcutorture.stall_cpu_holdoff= [KNL]
			Time to wait (s) after boot before inducing stall.

	rcutorture.stall_cpu_irqsoff= [KNL]
			Disable interrupts while stalling if set.

	rcutorture.stall_gp_kthread= [KNL]
			Duration (s) of forced sleep within RCU
			grace-period kthread to test RCU CPU stall
			warnings, zero to disable.  If both stall_cpu
			and stall_gp_kthread are specified, the
			kthread is starved first, then the CPU.

	rcutorture.stat_interval= [KNL]
			Time (s) between statistics printk()s.

	rcutorture.stutter= [KNL]
			Time (s) to stutter testing, for example, specifying
			five seconds causes the test to run for five seconds,
			wait for five seconds, and so on.  This tests RCU's
			ability to transition abruptly to and from idle.

	rcutorture.test_boost= [KNL]
			Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
			"Maybe" means test if the RCU implementation
			under test support RCU priority boosting.

	rcutorture.test_boost_duration= [KNL]
			Duration (s) of each individual boost test.

	rcutorture.test_boost_interval= [KNL]
			Interval (s) between each boost test.

	rcutorture.test_no_idle_hz= [KNL]
			Test RCU's dyntick-idle handling.  See also the
			rcutorture.shuffle_interval parameter.

	rcutorture.torture_type= [KNL]
			Specify the RCU implementation to test.

	rcutorture.verbose= [KNL]
			Enable additional printk() statements.

	rcupdate.rcu_cpu_stall_ftrace_dump= [KNL]
			Dump ftrace buffer after reporting RCU CPU
			stall warning.

	rcupdate.rcu_cpu_stall_suppress= [KNL]
			Suppress RCU CPU stall warning messages.

	rcupdate.rcu_cpu_stall_suppress_at_boot= [KNL]
			Suppress RCU CPU stall warning messages and
			rcutorture writer stall warnings that occur
			during early boot, that is, during the time
			before the init task is spawned.

	rcupdate.rcu_cpu_stall_timeout= [KNL]
			Set timeout for RCU CPU stall warning messages.

	rcupdate.rcu_expedited= [KNL]
			Use expedited grace-period primitives, for
			example, synchronize_rcu_expedited() instead
			of synchronize_rcu().  This reduces latency,
			but can increase CPU utilization, degrade
			real-time latency, and degrade energy efficiency.
			No effect on CONFIG_TINY_RCU kernels.

	rcupdate.rcu_normal= [KNL]
			Use only normal grace-period primitives,
			for example, synchronize_rcu() instead of
			synchronize_rcu_expedited().  This improves
			real-time latency, CPU utilization, and
			energy efficiency, but can expose users to
			increased grace-period latency.  This parameter
			overrides rcupdate.rcu_expedited.  No effect on
			CONFIG_TINY_RCU kernels.

	rcupdate.rcu_normal_after_boot= [KNL]
			Once boot has completed (that is, after
			rcu_end_inkernel_boot() has been invoked), use
			only normal grace-period primitives.  No effect
			on CONFIG_TINY_RCU kernels.

	rcupdate.rcu_task_ipi_delay= [KNL]
			Set time in jiffies during which RCU tasks will
			avoid sending IPIs, starting with the beginning
			of a given grace period.  Setting a large
			number avoids disturbing real-time workloads,
			but lengthens grace periods.

	rcupdate.rcu_task_stall_timeout= [KNL]
			Set timeout in jiffies for RCU task stall warning
			messages.  Disable with a value less than or equal
			to zero.

	rcupdate.rcu_self_test= [KNL]
			Run the RCU early boot self tests

	rdinit=		[KNL]
			Format: <full_path>
			Run specified binary instead of /init from the ramdisk,
			used for early userspace startup. See initrd.

	rdrand=		[X86]
			force - Override the decision by the kernel to hide the
				advertisement of RDRAND support (this affects
				certain AMD processors because of buggy BIOS
				support, specifically around the suspend/resume
				path).

	rdt=		[HW,X86,RDT]
			Turn on/off individual RDT features. List is:
			cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
			mba.
			E.g. to turn on cmt and turn off mba use:
				rdt=cmt,!mba

	reboot=		[KNL]
			Format (x86 or x86_64):
				[w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
				[[,]s[mp]#### \
				[[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
				[[,]f[orce]
			Where reboot_mode is one of warm (soft) or cold (hard) or gpio
					(prefix with 'panic_' to set mode for panic
					reboot only),
			      reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
			      reboot_force is either force or not specified,
			      reboot_cpu is s[mp]#### with #### being the processor
					to be used for rebooting.

	refscale.holdoff= [KNL]
			Set test-start holdoff period.  The purpose of
			this parameter is to delay the start of the
			test until boot completes in order to avoid
			interference.

	refscale.loops= [KNL]
			Set the number of loops over the synchronization
			primitive under test.  Increasing this number
			reduces noise due to loop start/end overhead,
			but the default has already reduced the per-pass
			noise to a handful of picoseconds on ca. 2020
			x86 laptops.

	refscale.nreaders= [KNL]
			Set number of readers.  The default value of -1
			selects N, where N is roughly 75% of the number
			of CPUs.  A value of zero is an interesting choice.

	refscale.nruns= [KNL]
			Set number of runs, each of which is dumped onto
			the console log.

	refscale.readdelay= [KNL]
			Set the read-side critical-section duration,
			measured in microseconds.

	refscale.scale_type= [KNL]
			Specify the read-protection implementation to test.

	refscale.shutdown= [KNL]
			Shut down the system at the end of the performance
			test.  This defaults to 1 (shut it down) when
			refscale is built into the kernel and to 0 (leave
			it running) when refscale is built as a module.

	refscale.verbose= [KNL]
			Enable additional printk() statements.

	relax_domain_level=
			[KNL, SMP] Set scheduler's default relax_domain_level.
			See Documentation/admin-guide/cgroup-v1/cpusets.rst.

	reserve=	[KNL,BUGS] Force kernel to ignore I/O ports or memory
			Format: <base1>,<size1>[,<base2>,<size2>,...]
			Reserve I/O ports or memory so the kernel won't use
			them.  If <base> is less than 0x10000, the region
			is assumed to be I/O ports; otherwise it is memory.

	reservetop=	[X86-32]
			Format: nn[KMG]
			Reserves a hole at the top of the kernel virtual
			address space.

	reservelow=	[X86]
			Format: nn[K]
			Set the amount of memory to reserve for BIOS at
			the bottom of the address space.

	reset_devices	[KNL] Force drivers to reset the underlying device
			during initialization.

	resume=		[SWSUSP]
			Specify the partition device for software suspend
			Format:
			{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}

	resume_offset=	[SWSUSP]
			Specify the offset from the beginning of the partition
			given by "resume=" at which the swap header is located,
			in <PAGE_SIZE> units (needed only for swap files).
			See  Documentation/power/swsusp-and-swap-files.rst

	resumedelay=	[HIBERNATION] Delay (in seconds) to pause before attempting to
			read the resume files

	resumewait	[HIBERNATION] Wait (indefinitely) for resume device to show up.
			Useful for devices that are detected asynchronously
			(e.g. USB and MMC devices).

	hibernate=	[HIBERNATION]
		noresume	Don't check if there's a hibernation image
				present during boot.
		nocompress	Don't compress/decompress hibernation images.
		no		Disable hibernation and resume.
		protect_image	Turn on image protection during restoration
				(that will set all pages holding image data
				during restoration read-only).

	retain_initrd	[RAM] Keep initrd memory after extraction

	rfkill.default_state=
		0	"airplane mode".  All wifi, bluetooth, wimax, gps, fm,
			etc. communication is blocked by default.
		1	Unblocked.

	rfkill.master_switch_mode=
		0	The "airplane mode" button does nothing.
		1	The "airplane mode" button toggles between everything
			blocked and the previous configuration.
		2	The "airplane mode" button toggles between everything
			blocked and everything unblocked.

	rhash_entries=	[KNL,NET]
			Set number of hash buckets for route cache

	ring3mwait=disable
			[KNL] Disable ring 3 MONITOR/MWAIT feature on supported
			CPUs.

	ro		[KNL] Mount root device read-only on boot

	rodata=		[KNL]
		on	Mark read-only kernel memory as read-only (default).
		off	Leave read-only kernel memory writable for debugging.

	rockchip.usb_uart
			Enable the uart passthrough on the designated usb port
			on Rockchip SoCs. When active, the signals of the
			debug-uart get routed to the D+ and D- pins of the usb
			port and the regular usb controller gets disabled.

	root=		[KNL] Root filesystem
			See name_to_dev_t comment in init/do_mounts.c.

	rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
			mount the root filesystem

	rootflags=	[KNL] Set root filesystem mount option string

	rootfstype=	[KNL] Set root filesystem type

	rootwait	[KNL] Wait (indefinitely) for root device to show up.
			Useful for devices that are detected asynchronously
			(e.g. USB and MMC devices).

	rproc_mem=nn[KMG][@address]
			[KNL,ARM,CMA] Remoteproc physical memory block.
			Memory area to be used by remote processor image,
			managed by CMA.

	rw		[KNL] Mount root device read-write on boot

	S		[KNL] Run init in single mode

	s390_iommu=	[HW,S390]
			Set s390 IOTLB flushing mode
		strict
			With strict flushing every unmap operation will result in
			an IOTLB flush. Default is lazy flushing before reuse,
			which is faster.

	sa1100ir	[NET]
			See drivers/net/irda/sa1100_ir.c.

	sbni=		[NET] Granch SBNI12 leased line adapter

	sched_debug	[KNL] Enables verbose scheduler debug messages.

	schedstats=	[KNL,X86] Enable or disable scheduled statistics.
			Allowed values are enable and disable. This feature
			incurs a small amount of overhead in the scheduler
			but is useful for debugging and performance tuning.

	sched_thermal_decay_shift=
			[KNL, SMP] Set a decay shift for scheduler thermal
			pressure signal. Thermal pressure signal follows the
			default decay period of other scheduler pelt
			signals(usually 32 ms but configurable). Setting
			sched_thermal_decay_shift will left shift the decay
			period for the thermal pressure signal by the shift
			value.
			i.e. with the default pelt decay period of 32 ms
			sched_thermal_decay_shift   thermal pressure decay pr
				1			64 ms
				2			128 ms
			and so on.
			Format: integer between 0 and 10
			Default is 0.

	scftorture.holdoff= [KNL]
			Number of seconds to hold off before starting
			test.  Defaults to zero for module insertion and
			to 10 seconds for built-in smp_call_function()
			tests.

	scftorture.longwait= [KNL]
			Request ridiculously long waits randomly selected
			up to the chosen limit in seconds.  Zero (the
			default) disables this feature.  Please note
			that requesting even small non-zero numbers of
			seconds can result in RCU CPU stall warnings,
			softlockup complaints, and so on.

	scftorture.nthreads= [KNL]
			Number of kthreads to spawn to invoke the
			smp_call_function() family of functions.
			The default of -1 specifies a number of kthreads
			equal to the number of CPUs.

	scftorture.onoff_holdoff= [KNL]
			Number seconds to wait after the start of the
			test before initiating CPU-hotplug operations.

	scftorture.onoff_interval= [KNL]
			Number seconds to wait between successive
			CPU-hotplug operations.  Specifying zero (which
			is the default) disables CPU-hotplug operations.

	scftorture.shutdown_secs= [KNL]
			The number of seconds following the start of the
			test after which to shut down the system.  The
			default of zero avoids shutting down the system.
			Non-zero values are useful for automated tests.

	scftorture.stat_interval= [KNL]
			The number of seconds between outputting the
			current test statistics to the console.  A value
			of zero disables statistics output.

	scftorture.stutter_cpus= [KNL]
			The number of jiffies to wait between each change
			to the set of CPUs under test.

	scftorture.use_cpus_read_lock= [KNL]
			Use use_cpus_read_lock() instead of the default
			preempt_disable() to disable CPU hotplug
			while invoking one of the smp_call_function*()
			functions.

	scftorture.verbose= [KNL]
			Enable additional printk() statements.

	scftorture.weight_single= [KNL]
			The probability weighting to use for the
			smp_call_function_single() function with a zero
			"wait" parameter.  A value of -1 selects the
			default if all other weights are -1.  However,
			if at least one weight has some other value, a
			value of -1 will instead select a weight of zero.

	scftorture.weight_single_wait= [KNL]
			The probability weighting to use for the
			smp_call_function_single() function with a
			non-zero "wait" parameter.  See weight_single.

	scftorture.weight_many= [KNL]
			The probability weighting to use for the
			smp_call_function_many() function with a zero
			"wait" parameter.  See weight_single.
			Note well that setting a high probability for
			this weighting can place serious IPI load
			on the system.

	scftorture.weight_many_wait= [KNL]
			The probability weighting to use for the
			smp_call_function_many() function with a
			non-zero "wait" parameter.  See weight_single
			and weight_many.

	scftorture.weight_all= [KNL]
			The probability weighting to use for the
			smp_call_function_all() function with a zero
			"wait" parameter.  See weight_single and
			weight_many.

	scftorture.weight_all_wait= [KNL]
			The probability weighting to use for the
			smp_call_function_all() function with a
			non-zero "wait" parameter.  See weight_single
			and weight_many.

	skew_tick=	[KNL] Offset the periodic timer tick per cpu to mitigate
			xtime_lock contention on larger systems, and/or RCU lock
			contention on all systems with CONFIG_MAXSMP set.
			Format: { "0" | "1" }
			0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
			1 -- enable.
			Note: increases power consumption, thus should only be
			enabled if running jitter sensitive (HPC/RT) workloads.

	security=	[SECURITY] Choose a legacy "major" security module to
			enable at boot. This has been deprecated by the
			"lsm=" parameter.

	selinux=	[SELINUX] Disable or enable SELinux at boot time.
			Format: { "0" | "1" }
			See security/selinux/Kconfig help text.
			0 -- disable.
			1 -- enable.
			Default value is 1.

	apparmor=	[APPARMOR] Disable or enable AppArmor at boot time
			Format: { "0" | "1" }
			See security/apparmor/Kconfig help text
			0 -- disable.
			1 -- enable.
			Default value is set via kernel config option.

	serialnumber	[BUGS=X86-32]

	shapers=	[NET]
			Maximal number of shapers.

	simeth=		[IA-64]
	simscsi=

	slram=		[HW,MTD]

	slab_nomerge	[MM]
			Disable merging of slabs with similar size. May be
			necessary if there is some reason to distinguish
			allocs to different slabs, especially in hardened
			environments where the risk of heap overflows and
			layout control by attackers can usually be
			frustrated by disabling merging. This will reduce
			most of the exposure of a heap attack to a single
			cache (risks via metadata attacks are mostly
			unchanged). Debug options disable merging on their
			own.
			For more information see Documentation/vm/slub.rst.

	slab_max_order=	[MM, SLAB]
			Determines the maximum allowed order for slabs.
			A high setting may cause OOMs due to memory
			fragmentation.  Defaults to 1 for systems with
			more than 32MB of RAM, 0 otherwise.

	slub_debug[=options[,slabs][;[options[,slabs]]...]	[MM, SLUB]
			Enabling slub_debug allows one to determine the
			culprit if slab objects become corrupted. Enabling
			slub_debug can create guard zones around objects and
			may poison objects when not in use. Also tracks the
			last alloc / free. For more information see
			Documentation/vm/slub.rst.

	slub_memcg_sysfs=	[MM, SLUB]
			Determines whether to enable sysfs directories for
			memory cgroup sub-caches. 1 to enable, 0 to disable.
			The default is determined by CONFIG_SLUB_MEMCG_SYSFS_ON.
			Enabling this can lead to a very high number of	debug
			directories and files being created under
			/sys/kernel/slub.

	slub_max_order= [MM, SLUB]
			Determines the maximum allowed order for slabs.
			A high setting may cause OOMs due to memory
			fragmentation. For more information see
			Documentation/vm/slub.rst.

	slub_min_objects=	[MM, SLUB]
			The minimum number of objects per slab. SLUB will
			increase the slab order up to slub_max_order to
			generate a sufficiently large slab able to contain
			the number of objects indicated. The higher the number
			of objects the smaller the overhead of tracking slabs
			and the less frequently locks need to be acquired.
			For more information see Documentation/vm/slub.rst.

	slub_min_order=	[MM, SLUB]
			Determines the minimum page order for slabs. Must be
			lower than slub_max_order.
			For more information see Documentation/vm/slub.rst.

	slub_nomerge	[MM, SLUB]
			Same with slab_nomerge. This is supported for legacy.
			See slab_nomerge for more information.

	smart2=		[HW]
			Format: <io1>[,<io2>[,...,<io8>]]

	smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
	smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
	smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
	smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
	smsc-ircc2.ircc_irq=	[HW] IRQ line
	smsc-ircc2.ircc_dma=	[HW] DMA channel
	smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
				0: Toshiba Satellite 1800 (GP data pin select)
				1: Fast pin select (default)
				2: ATC IRMode

	smt		[KNL,S390] Set the maximum number of threads (logical
			CPUs) to use per physical CPU on systems capable of
			symmetric multithreading (SMT). Will be capped to the
			actual hardware limit.
			Format: <integer>
			Default: -1 (no limit)

	softlockup_panic=
			[KNL] Should the soft-lockup detector generate panics.
			Format: 0 | 1

			A value of 1 instructs the soft-lockup detector
			to panic the machine when a soft-lockup occurs. It is
			also controlled by the kernel.softlockup_panic sysctl
			and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the
			respective build-time switch to that functionality.

	softlockup_all_cpu_backtrace=
			[KNL] Should the soft-lockup detector generate
			backtraces on all cpus.
			Format: 0 | 1

	sonypi.*=	[HW] Sony Programmable I/O Control Device driver
			See Documentation/admin-guide/laptops/sonypi.rst

	spectre_v2=	[X86] Control mitigation of Spectre variant 2
			(indirect branch speculation) vulnerability.
			The default operation protects the kernel from
			user space attacks.

			on   - unconditionally enable, implies
			       spectre_v2_user=on
			off  - unconditionally disable, implies
			       spectre_v2_user=off
			auto - kernel detects whether your CPU model is
			       vulnerable

			Selecting 'on' will, and 'auto' may, choose a
			mitigation method at run time according to the
			CPU, the available microcode, the setting of the
			CONFIG_RETPOLINE configuration option, and the
			compiler with which the kernel was built.

			Selecting 'on' will also enable the mitigation
			against user space to user space task attacks.

			Selecting 'off' will disable both the kernel and
			the user space protections.

			Specific mitigations can also be selected manually:

			retpoline	  - replace indirect branches
			retpoline,generic - google's original retpoline
			retpoline,amd     - AMD-specific minimal thunk

			Not specifying this option is equivalent to
			spectre_v2=auto.

	spectre_v2_user=
			[X86] Control mitigation of Spectre variant 2
		        (indirect branch speculation) vulnerability between
		        user space tasks

			on	- Unconditionally enable mitigations. Is
				  enforced by spectre_v2=on

			off     - Unconditionally disable mitigations. Is
				  enforced by spectre_v2=off

			prctl   - Indirect branch speculation is enabled,
				  but mitigation can be enabled via prctl
				  per thread.  The mitigation control state
				  is inherited on fork.

			prctl,ibpb
				- Like "prctl" above, but only STIBP is
				  controlled per thread. IBPB is issued
				  always when switching between different user
				  space processes.

			seccomp
				- Same as "prctl" above, but all seccomp
				  threads will enable the mitigation unless
				  they explicitly opt out.

			seccomp,ibpb
				- Like "seccomp" above, but only STIBP is
				  controlled per thread. IBPB is issued
				  always when switching between different
				  user space processes.

			auto    - Kernel selects the mitigation depending on
				  the available CPU features and vulnerability.

			Default mitigation:
			If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl"

			Not specifying this option is equivalent to
			spectre_v2_user=auto.

	spec_store_bypass_disable=
			[HW] Control Speculative Store Bypass (SSB) Disable mitigation
			(Speculative Store Bypass vulnerability)

			Certain CPUs are vulnerable to an exploit against a
			a common industry wide performance optimization known
			as "Speculative Store Bypass" in which recent stores
			to the same memory location may not be observed by
			later loads during speculative execution. The idea
			is that such stores are unlikely and that they can
			be detected prior to instruction retirement at the
			end of a particular speculation execution window.

			In vulnerable processors, the speculatively forwarded
			store can be used in a cache side channel attack, for
			example to read memory to which the attacker does not
			directly have access (e.g. inside sandboxed code).

			This parameter controls whether the Speculative Store
			Bypass optimization is used.

			On x86 the options are:

			on      - Unconditionally disable Speculative Store Bypass
			off     - Unconditionally enable Speculative Store Bypass
			auto    - Kernel detects whether the CPU model contains an
				  implementation of Speculative Store Bypass and
				  picks the most appropriate mitigation. If the
				  CPU is not vulnerable, "off" is selected. If the
				  CPU is vulnerable the default mitigation is
				  architecture and Kconfig dependent. See below.
			prctl   - Control Speculative Store Bypass per thread
				  via prctl. Speculative Store Bypass is enabled
				  for a process by default. The state of the control
				  is inherited on fork.
			seccomp - Same as "prctl" above, but all seccomp threads
				  will disable SSB unless they explicitly opt out.

			Default mitigations:
			X86:	If CONFIG_SECCOMP=y "seccomp", otherwise "prctl"

			On powerpc the options are:

			on,auto - On Power8 and Power9 insert a store-forwarding
				  barrier on kernel entry and exit. On Power7
				  perform a software flush on kernel entry and
				  exit.
			off	- No action.

			Not specifying this option is equivalent to
			spec_store_bypass_disable=auto.

	spia_io_base=	[HW,MTD]
	spia_fio_base=
	spia_pedr=
	spia_peddr=

	split_lock_detect=
			[X86] Enable split lock detection

			When enabled (and if hardware support is present), atomic
			instructions that access data across cache line
			boundaries will result in an alignment check exception.

			off	- not enabled

			warn	- the kernel will emit rate limited warnings
				  about applications triggering the #AC
				  exception. This mode is the default on CPUs
				  that supports split lock detection.

			fatal	- the kernel will send SIGBUS to applications
				  that trigger the #AC exception.

			If an #AC exception is hit in the kernel or in
			firmware (i.e. not while executing in user mode)
			the kernel will oops in either "warn" or "fatal"
			mode.

	srbds=		[X86,INTEL]
			Control the Special Register Buffer Data Sampling
			(SRBDS) mitigation.

			Certain CPUs are vulnerable to an MDS-like
			exploit which can leak bits from the random
			number generator.

			By default, this issue is mitigated by
			microcode.  However, the microcode fix can cause
			the RDRAND and RDSEED instructions to become
			much slower.  Among other effects, this will
			result in reduced throughput from /dev/urandom.

			The microcode mitigation can be disabled with
			the following option:

			off:    Disable mitigation and remove
				performance impact to RDRAND and RDSEED

	srcutree.counter_wrap_check [KNL]
			Specifies how frequently to check for
			grace-period sequence counter wrap for the
			srcu_data structure's ->srcu_gp_seq_needed field.
			The greater the number of bits set in this kernel
			parameter, the less frequently counter wrap will
			be checked for.  Note that the bottom two bits
			are ignored.

	srcutree.exp_holdoff [KNL]
			Specifies how many nanoseconds must elapse
			since the end of the last SRCU grace period for
			a given srcu_struct until the next normal SRCU
			grace period will be considered for automatic
			expediting.  Set to zero to disable automatic
			expediting.

	ssbd=		[ARM64,HW]
			Speculative Store Bypass Disable control

			On CPUs that are vulnerable to the Speculative
			Store Bypass vulnerability and offer a
			firmware based mitigation, this parameter
			indicates how the mitigation should be used:

			force-on:  Unconditionally enable mitigation for
				   for both kernel and userspace
			force-off: Unconditionally disable mitigation for
				   for both kernel and userspace
			kernel:    Always enable mitigation in the
				   kernel, and offer a prctl interface
				   to allow userspace to register its
				   interest in being mitigated too.

	stack_guard_gap=	[MM]
			override the default stack gap protection. The value
			is in page units and it defines how many pages prior
			to (for stacks growing down) resp. after (for stacks
			growing up) the main stack are reserved for no other
			mapping. Default value is 256 pages.

	stacktrace	[FTRACE]
			Enabled the stack tracer on boot up.

	stacktrace_filter=[function-list]
			[FTRACE] Limit the functions that the stack tracer
			will trace at boot up. function-list is a comma separated
			list of functions. This list can be changed at run
			time by the stack_trace_filter file in the debugfs
			tracing directory. Note, this enables stack tracing
			and the stacktrace above is not needed.

	sti=		[PARISC,HW]
			Format: <num>
			Set the STI (builtin display/keyboard on the HP-PARISC
			machines) console (graphic card) which should be used
			as the initial boot-console.
			See also comment in drivers/video/console/sticore.c.

	sti_font=	[HW]
			See comment in drivers/video/console/sticore.c.

	stifb=		[HW]
			Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]

	sunrpc.min_resvport=
	sunrpc.max_resvport=
			[NFS,SUNRPC]
			SunRPC servers often require that client requests
			originate from a privileged port (i.e. a port in the
			range 0 < portnr < 1024).
			An administrator who wishes to reserve some of these
			ports for other uses may adjust the range that the
			kernel's sunrpc client considers to be privileged
			using these two parameters to set the minimum and
			maximum port values.

	sunrpc.svc_rpc_per_connection_limit=
			[NFS,SUNRPC]
			Limit the number of requests that the server will
			process in parallel from a single connection.
			The default value is 0 (no limit).

	sunrpc.pool_mode=
			[NFS]
			Control how the NFS server code allocates CPUs to
			service thread pools.  Depending on how many NICs
			you have and where their interrupts are bound, this
			option will affect which CPUs will do NFS serving.
			Note: this parameter cannot be changed while the
			NFS server is running.

			auto	    the server chooses an appropriate mode
				    automatically using heuristics
			global	    a single global pool contains all CPUs
			percpu	    one pool for each CPU
			pernode	    one pool for each NUMA node (equivalent
				    to global on non-NUMA machines)

	sunrpc.tcp_slot_table_entries=
	sunrpc.udp_slot_table_entries=
			[NFS,SUNRPC]
			Sets the upper limit on the number of simultaneous
			RPC calls that can be sent from the client to a
			server. Increasing these values may allow you to
			improve throughput, but will also increase the
			amount of memory reserved for use by the client.

	suspend.pm_test_delay=
			[SUSPEND]
			Sets the number of seconds to remain in a suspend test
			mode before resuming the system (see
			/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
			is set. Default value is 5.

	svm=		[PPC]
			Format: { on | off | y | n | 1 | 0 }
			This parameter controls use of the Protected
			Execution Facility on pSeries.

	swapaccount=[0|1]
			[KNL] Enable accounting of swap in memory resource
			controller if no parameter or 1 is given or disable
			it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)

	swiotlb=	[ARM,IA-64,PPC,MIPS,X86]
			Format: { <int> | force | noforce }
			<int> -- Number of I/O TLB slabs
			force -- force using of bounce buffers even if they
			         wouldn't be automatically used by the kernel
			noforce -- Never use bounce buffers (for debugging)

	switches=	[HW,M68k]

	sysctl.*=	[KNL]
			Set a sysctl parameter, right before loading the init
			process, as if the value was written to the respective
			/proc/sys/... file. Both '.' and '/' are recognized as
			separators. Unrecognized parameters and invalid values
			are reported in the kernel log. Sysctls registered
			later by a loaded module cannot be set this way.
			Example: sysctl.vm.swappiness=40

	sysfs.deprecated=0|1 [KNL]
			Enable/disable old style sysfs layout for old udev
			on older distributions. When this option is enabled
			very new udev will not work anymore. When this option
			is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
			in older udev will not work anymore.
			Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
			the kernel configuration.

	sysrq_always_enabled
			[KNL]
			Ignore sysrq setting - this boot parameter will
			neutralize any effect of /proc/sys/kernel/sysrq.
			Useful for debugging.

	tcpmhash_entries= [KNL,NET]
			Set the number of tcp_metrics_hash slots.
			Default value is 8192 or 16384 depending on total
			ram pages. This is used to specify the TCP metrics
			cache size. See Documentation/networking/ip-sysctl.rst
			"tcp_no_metrics_save" section for more details.

	tdfx=		[HW,DRM]

	test_suspend=	[SUSPEND][,N]
			Specify "mem" (for Suspend-to-RAM) or "standby" (for
			standby suspend) or "freeze" (for suspend type freeze)
			as the system sleep state during system startup with
			the optional capability to repeat N number of times.
			The system is woken from this state using a
			wakeup-capable RTC alarm.

	thash_entries=	[KNL,NET]
			Set number of hash buckets for TCP connection

	thermal.act=	[HW,ACPI]
			-1: disable all active trip points in all thermal zones
			<degrees C>: override all lowest active trip points

	thermal.crt=	[HW,ACPI]
			-1: disable all critical trip points in all thermal zones
			<degrees C>: override all critical trip points

	thermal.nocrt=	[HW,ACPI]
			Set to disable actions on ACPI thermal zone
			critical and hot trip points.

	thermal.off=	[HW,ACPI]
			1: disable ACPI thermal control

	thermal.psv=	[HW,ACPI]
			-1: disable all passive trip points
			<degrees C>: override all passive trip points to this
			value

	thermal.tzp=	[HW,ACPI]
			Specify global default ACPI thermal zone polling rate
			<deci-seconds>: poll all this frequency
			0: no polling (default)

	threadirqs	[KNL]
			Force threading of all interrupt handlers except those
			marked explicitly IRQF_NO_THREAD.

	topology=	[S390]
			Format: {off | on}
			Specify if the kernel should make use of the cpu
			topology information if the hardware supports this.
			The scheduler will make use of this information and
			e.g. base its process migration decisions on it.
			Default is on.

	topology_updates= [KNL, PPC, NUMA]
			Format: {off}
			Specify if the kernel should ignore (off)
			topology updates sent by the hypervisor to this
			LPAR.

	torture.disable_onoff_at_boot= [KNL]
			Prevent the CPU-hotplug component of torturing
			until after init has spawned.

	torture.ftrace_dump_at_shutdown= [KNL]
			Dump the ftrace buffer at torture-test shutdown,
			even if there were no errors.  This can be a
			very costly operation when many torture tests
			are running concurrently, especially on systems
			with rotating-rust storage.

	tp720=		[HW,PS2]

	tpm_suspend_pcr=[HW,TPM]
			Format: integer pcr id
			Specify that at suspend time, the tpm driver
			should extend the specified pcr with zeros,
			as a workaround for some chips which fail to
			flush the last written pcr on TPM_SaveState.
			This will guarantee that all the other pcrs
			are saved.

	trace_buf_size=nn[KMG]
			[FTRACE] will set tracing buffer size on each cpu.

	trace_event=[event-list]
			[FTRACE] Set and start specified trace events in order
			to facilitate early boot debugging. The event-list is a
			comma separated list of trace events to enable. See
			also Documentation/trace/events.rst

	trace_options=[option-list]
			[FTRACE] Enable or disable tracer options at boot.
			The option-list is a comma delimited list of options
			that can be enabled or disabled just as if you were
			to echo the option name into

			    /sys/kernel/debug/tracing/trace_options

			For example, to enable stacktrace option (to dump the
			stack trace of each event), add to the command line:

			      trace_options=stacktrace

			See also Documentation/trace/ftrace.rst "trace options"
			section.

	tp_printk[FTRACE]
			Have the tracepoints sent to printk as well as the
			tracing ring buffer. This is useful for early boot up
			where the system hangs or reboots and does not give the
			option for reading the tracing buffer or performing a
			ftrace_dump_on_oops.

			To turn off having tracepoints sent to printk,
			 echo 0 > /proc/sys/kernel/tracepoint_printk
			Note, echoing 1 into this file without the
			tracepoint_printk kernel cmdline option has no effect.

			** CAUTION **

			Having tracepoints sent to printk() and activating high
			frequency tracepoints such as irq or sched, can cause
			the system to live lock.

	traceoff_on_warning
			[FTRACE] enable this option to disable tracing when a
			warning is hit. This turns off "tracing_on". Tracing can
			be enabled again by echoing '1' into the "tracing_on"
			file located in /sys/kernel/debug/tracing/

			This option is useful, as it disables the trace before
			the WARNING dump is called, which prevents the trace to
			be filled with content caused by the warning output.

			This option can also be set at run time via the sysctl
			option:  kernel/traceoff_on_warning

	transparent_hugepage=
			[KNL]
			Format: [always|madvise|never]
			Can be used to control the default behavior of the system
			with respect to transparent hugepages.
			See Documentation/admin-guide/mm/transhuge.rst
			for more details.

	tsc=		Disable clocksource stability checks for TSC.
			Format: <string>
			[x86] reliable: mark tsc clocksource as reliable, this
			disables clocksource verification at runtime, as well
			as the stability checks done at bootup.	Used to enable
			high-resolution timer mode on older hardware, and in
			virtualized environment.
			[x86] noirqtime: Do not use TSC to do irq accounting.
			Used to run time disable IRQ_TIME_ACCOUNTING on any
			platforms where RDTSC is slow and this accounting
			can add overhead.
			[x86] unstable: mark the TSC clocksource as unstable, this
			marks the TSC unconditionally unstable at bootup and
			avoids any further wobbles once the TSC watchdog notices.
			[x86] nowatchdog: disable clocksource watchdog. Used
			in situations with strict latency requirements (where
			interruptions from clocksource watchdog are not
			acceptable).

	tsc_early_khz=  [X86] Skip early TSC calibration and use the given
			value instead. Useful when the early TSC frequency discovery
			procedure is not reliable, such as on overclocked systems
			with CPUID.16h support and partial CPUID.15h support.
			Format: <unsigned int>

	tsx=		[X86] Control Transactional Synchronization
			Extensions (TSX) feature in Intel processors that
			support TSX control.

			This parameter controls the TSX feature. The options are:

			on	- Enable TSX on the system. Although there are
				mitigations for all known security vulnerabilities,
				TSX has been known to be an accelerator for
				several previous speculation-related CVEs, and
				so there may be unknown	security risks associated
				with leaving it enabled.

			off	- Disable TSX on the system. (Note that this
				option takes effect only on newer CPUs which are
				not vulnerable to MDS, i.e., have
				MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1 and which get
				the new IA32_TSX_CTRL MSR through a microcode
				update. This new MSR allows for the reliable
				deactivation of the TSX functionality.)

			auto	- Disable TSX if X86_BUG_TAA is present,
				  otherwise enable TSX on the system.

			Not specifying this option is equivalent to tsx=off.

			See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
			for more details.

	tsx_async_abort= [X86,INTEL] Control mitigation for the TSX Async
			Abort (TAA) vulnerability.

			Similar to Micro-architectural Data Sampling (MDS)
			certain CPUs that support Transactional
			Synchronization Extensions (TSX) are vulnerable to an
			exploit against CPU internal buffers which can forward
			information to a disclosure gadget under certain
			conditions.

			In vulnerable processors, the speculatively forwarded
			data can be used in a cache side channel attack, to
			access data to which the attacker does not have direct
			access.

			This parameter controls the TAA mitigation.  The
			options are:

			full       - Enable TAA mitigation on vulnerable CPUs
				     if TSX is enabled.

			full,nosmt - Enable TAA mitigation and disable SMT on
				     vulnerable CPUs. If TSX is disabled, SMT
				     is not disabled because CPU is not
				     vulnerable to cross-thread TAA attacks.
			off        - Unconditionally disable TAA mitigation

			On MDS-affected machines, tsx_async_abort=off can be
			prevented by an active MDS mitigation as both vulnerabilities
			are mitigated with the same mechanism so in order to disable
			this mitigation, you need to specify mds=off too.

			Not specifying this option is equivalent to
			tsx_async_abort=full.  On CPUs which are MDS affected
			and deploy MDS mitigation, TAA mitigation is not
			required and doesn't provide any additional
			mitigation.

			For details see:
			Documentation/admin-guide/hw-vuln/tsx_async_abort.rst

	turbografx.map[2|3]=	[HW,JOY]
			TurboGraFX parallel port interface
			Format:
			<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
			See also Documentation/input/devices/joystick-parport.rst

	udbg-immortal	[PPC] When debugging early kernel crashes that
			happen after console_init() and before a proper
			console driver takes over, this boot options might
			help "seeing" what's going on.

	uhash_entries=	[KNL,NET]
			Set number of hash buckets for UDP/UDP-Lite connections

	uhci-hcd.ignore_oc=
			[USB] Ignore overcurrent events (default N).
			Some badly-designed motherboards generate lots of
			bogus events, for ports that aren't wired to
			anything.  Set this parameter to avoid log spamming.
			Note that genuine overcurrent events won't be
			reported either.

	unknown_nmi_panic
			[X86] Cause panic on unknown NMI.

	usbcore.authorized_default=
			[USB] Default USB device authorization:
			(default -1 = authorized except for wireless USB,
			0 = not authorized, 1 = authorized, 2 = authorized
			if device connected to internal port)

	usbcore.autosuspend=
			[USB] The autosuspend time delay (in seconds) used
			for newly-detected USB devices (default 2).  This
			is the time required before an idle device will be
			autosuspended.  Devices for which the delay is set
			to a negative value won't be autosuspended at all.

	usbcore.usbfs_snoop=
			[USB] Set to log all usbfs traffic (default 0 = off).

	usbcore.usbfs_snoop_max=
			[USB] Maximum number of bytes to snoop in each URB
			(default = 65536).

	usbcore.blinkenlights=
			[USB] Set to cycle leds on hubs (default 0 = off).

	usbcore.old_scheme_first=
			[USB] Start with the old device initialization
			scheme (default 0 = off).

	usbcore.usbfs_memory_mb=
			[USB] Memory limit (in MB) for buffers allocated by
			usbfs (default = 16, 0 = max = 2047).

	usbcore.use_both_schemes=
			[USB] Try the other device initialization scheme
			if the first one fails (default 1 = enabled).

	usbcore.initial_descriptor_timeout=
			[USB] Specifies timeout for the initial 64-byte
			USB_REQ_GET_DESCRIPTOR request in milliseconds
			(default 5000 = 5.0 seconds).

	usbcore.nousb	[USB] Disable the USB subsystem

	usbcore.quirks=
			[USB] A list of quirk entries to augment the built-in
			usb core quirk list. List entries are separated by
			commas. Each entry has the form
			VendorID:ProductID:Flags. The IDs are 4-digit hex
			numbers and Flags is a set of letters. Each letter
			will change the built-in quirk; setting it if it is
			clear and clearing it if it is set. The letters have
			the following meanings:
				a = USB_QUIRK_STRING_FETCH_255 (string
					descriptors must not be fetched using
					a 255-byte read);
				b = USB_QUIRK_RESET_RESUME (device can't resume
					correctly so reset it instead);
				c = USB_QUIRK_NO_SET_INTF (device can't handle
					Set-Interface requests);
				d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't
					handle its Configuration or Interface
					strings);
				e = USB_QUIRK_RESET (device can't be reset
					(e.g morph devices), don't use reset);
				f = USB_QUIRK_HONOR_BNUMINTERFACES (device has
					more interface descriptions than the
					bNumInterfaces count, and can't handle
					talking to these interfaces);
				g = USB_QUIRK_DELAY_INIT (device needs a pause
					during initialization, after we read
					the device descriptor);
				h = USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL (For
					high speed and super speed interrupt
					endpoints, the USB 2.0 and USB 3.0 spec
					require the interval in microframes (1
					microframe = 125 microseconds) to be
					calculated as interval = 2 ^
					(bInterval-1).
					Devices with this quirk report their
					bInterval as the result of this
					calculation instead of the exponent
					variable used in the calculation);
				i = USB_QUIRK_DEVICE_QUALIFIER (device can't
					handle device_qualifier descriptor
					requests);
				j = USB_QUIRK_IGNORE_REMOTE_WAKEUP (device
					generates spurious wakeup, ignore
					remote wakeup capability);
				k = USB_QUIRK_NO_LPM (device can't handle Link
					Power Management);
				l = USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL
					(Device reports its bInterval as linear
					frames instead of the USB 2.0
					calculation);
				m = USB_QUIRK_DISCONNECT_SUSPEND (Device needs
					to be disconnected before suspend to
					prevent spurious wakeup);
				n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a
					pause after every control message);
				o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra
					delay after resetting its port);
			Example: quirks=0781:5580:bk,0a5c:5834:gij

	usbhid.mousepoll=
			[USBHID] The interval which mice are to be polled at.

	usbhid.jspoll=
			[USBHID] The interval which joysticks are to be polled at.

	usbhid.kbpoll=
			[USBHID] The interval which keyboards are to be polled at.

	usb-storage.delay_use=
			[UMS] The delay in seconds before a new device is
			scanned for Logical Units (default 1).

	usb-storage.quirks=
			[UMS] A list of quirks entries to supplement or
			override the built-in unusual_devs list.  List
			entries are separated by commas.  Each entry has
			the form VID:PID:Flags where VID and PID are Vendor
			and Product ID values (4-digit hex numbers) and
			Flags is a set of characters, each corresponding
			to a common usb-storage quirk flag as follows:
				a = SANE_SENSE (collect more than 18 bytes
					of sense data, not on uas);
				b = BAD_SENSE (don't collect more than 18
					bytes of sense data, not on uas);
				c = FIX_CAPACITY (decrease the reported
					device capacity by one sector);
				d = NO_READ_DISC_INFO (don't use
					READ_DISC_INFO command, not on uas);
				e = NO_READ_CAPACITY_16 (don't use
					READ_CAPACITY_16 command);
				f = NO_REPORT_OPCODES (don't use report opcodes
					command, uas only);
				g = MAX_SECTORS_240 (don't transfer more than
					240 sectors at a time, uas only);
				h = CAPACITY_HEURISTICS (decrease the
					reported device capacity by one
					sector if the number is odd);
				i = IGNORE_DEVICE (don't bind to this
					device);
				j = NO_REPORT_LUNS (don't use report luns
					command, uas only);
				l = NOT_LOCKABLE (don't try to lock and
					unlock ejectable media, not on uas);
				m = MAX_SECTORS_64 (don't transfer more
					than 64 sectors = 32 KB at a time,
					not on uas);
				n = INITIAL_READ10 (force a retry of the
					initial READ(10) command, not on uas);
				o = CAPACITY_OK (accept the capacity
					reported by the device, not on uas);
				p = WRITE_CACHE (the device cache is ON
					by default, not on uas);
				r = IGNORE_RESIDUE (the device reports
					bogus residue values, not on uas);
				s = SINGLE_LUN (the device has only one
					Logical Unit);
				t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
					commands, uas only);
				u = IGNORE_UAS (don't bind to the uas driver);
				w = NO_WP_DETECT (don't test whether the
					medium is write-protected).
				y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE
					even if the device claims no cache,
					not on uas)
			Example: quirks=0419:aaf5:rl,0421:0433:rc

	user_debug=	[KNL,ARM]
			Format: <int>
			See arch/arm/Kconfig.debug help text.
				 1 - undefined instruction events
				 2 - system calls
				 4 - invalid data aborts
				 8 - SIGSEGV faults
				16 - SIGBUS faults
			Example: user_debug=31

	userpte=
			[X86] Flags controlling user PTE allocations.

				nohigh = do not allocate PTE pages in
					HIGHMEM regardless of setting
					of CONFIG_HIGHPTE.

	vdso=		[X86,SH]
			On X86_32, this is an alias for vdso32=.  Otherwise:

			vdso=1: enable VDSO (the default)
			vdso=0: disable VDSO mapping

	vdso32=		[X86] Control the 32-bit vDSO
			vdso32=1: enable 32-bit VDSO
			vdso32=0 or vdso32=2: disable 32-bit VDSO

			See the help text for CONFIG_COMPAT_VDSO for more
			details.  If CONFIG_COMPAT_VDSO is set, the default is
			vdso32=0; otherwise, the default is vdso32=1.

			For compatibility with older kernels, vdso32=2 is an
			alias for vdso32=0.

			Try vdso32=0 if you encounter an error that says:
			dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!

	vector=		[IA-64,SMP]
			vector=percpu: enable percpu vector domain

	video=		[FB] Frame buffer configuration
			See Documentation/fb/modedb.rst.

	video.brightness_switch_enabled= [0,1]
			If set to 1, on receiving an ACPI notify event
			generated by hotkey, video driver will adjust brightness
			level and then send out the event to user space through
			the allocated input device; If set to 0, video driver
			will only send out the event without touching backlight
			brightness level.
			default: 1

	virtio_mmio.device=
			[VMMIO] Memory mapped virtio (platform) device.

				<size>@<baseaddr>:<irq>[:<id>]
			where:
				<size>     := size (can use standard suffixes
						like K, M and G)
				<baseaddr> := physical base address
				<irq>      := interrupt number (as passed to
						request_irq())
				<id>       := (optional) platform device id
			example:
				virtio_mmio.device=1K@0x100b0000:48:7

			Can be used multiple times for multiple devices.

	vga=		[BOOT,X86-32] Select a particular video mode
			See Documentation/x86/boot.rst and
			Documentation/admin-guide/svga.rst.
			Use vga=ask for menu.
			This is actually a boot loader parameter; the value is
			passed to the kernel using a special protocol.

	vm_debug[=options]	[KNL] Available with CONFIG_DEBUG_VM=y.
			May slow down system boot speed, especially when
			enabled on systems with a large amount of memory.
			All options are enabled by default, and this
			interface is meant to allow for selectively
			enabling or disabling specific virtual memory
			debugging features.

			Available options are:
			  P	Enable page structure init time poisoning
			  -	Disable all of the above options

	vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
			size of <nn>. This can be used to increase the
			minimum size (128MB on x86). It can also be used to
			decrease the size and leave more room for directly
			mapped kernel RAM.

	vmcp_cma=nn[MG]	[KNL,S390]
			Sets the memory size reserved for contiguous memory
			allocations for the vmcp device driver.

	vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
			Format: <command>

	vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
			Format: <command>

	vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
			Format: <command>

	vsyscall=	[X86-64]
			Controls the behavior of vsyscalls (i.e. calls to
			fixed addresses of 0xffffffffff600x00 from legacy
			code).  Most statically-linked binaries and older
			versions of glibc use these calls.  Because these
			functions are at fixed addresses, they make nice
			targets for exploits that can control RIP.

			emulate     [default] Vsyscalls turn into traps and are
			            emulated reasonably safely.  The vsyscall
				    page is readable.

			xonly       Vsyscalls turn into traps and are
			            emulated reasonably safely.  The vsyscall
				    page is not readable.

			none        Vsyscalls don't work at all.  This makes
			            them quite hard to use for exploits but
			            might break your system.

	vt.color=	[VT] Default text color.
			Format: 0xYX, X = foreground, Y = background.
			Default: 0x07 = light gray on black.

	vt.cur_default=	[VT] Default cursor shape.
			Format: 0xCCBBAA, where AA, BB, and CC are the same as
			the parameters of the <Esc>[?A;B;Cc escape sequence;
			see VGA-softcursor.txt. Default: 2 = underline.

	vt.default_blu=	[VT]
			Format: <blue0>,<blue1>,<blue2>,...,<blue15>
			Change the default blue palette of the console.
			This is a 16-member array composed of values
			ranging from 0-255.

	vt.default_grn=	[VT]
			Format: <green0>,<green1>,<green2>,...,<green15>
			Change the default green palette of the console.
			This is a 16-member array composed of values
			ranging from 0-255.

	vt.default_red=	[VT]
			Format: <red0>,<red1>,<red2>,...,<red15>
			Change the default red palette of the console.
			This is a 16-member array composed of values
			ranging from 0-255.

	vt.default_utf8=
			[VT]
			Format=<0|1>
			Set system-wide default UTF-8 mode for all tty's.
			Default is 1, i.e. UTF-8 mode is enabled for all
			newly opened terminals.

	vt.global_cursor_default=
			[VT]
			Format=<-1|0|1>
			Set system-wide default for whether a cursor
			is shown on new VTs. Default is -1,
			i.e. cursors will be created by default unless
			overridden by individual drivers. 0 will hide
			cursors, 1 will display them.

	vt.italic=	[VT] Default color for italic text; 0-15.
			Default: 2 = green.

	vt.underline=	[VT] Default color for underlined text; 0-15.
			Default: 3 = cyan.

	watchdog timers	[HW,WDT] For information on watchdog timers,
			see Documentation/watchdog/watchdog-parameters.rst
			or other driver-specific files in the
			Documentation/watchdog/ directory.

	watchdog_thresh=
			[KNL]
			Set the hard lockup detector stall duration
			threshold in seconds. The soft lockup detector
			threshold is set to twice the value. A value of 0
			disables both lockup detectors. Default is 10
			seconds.

	workqueue.watchdog_thresh=
			If CONFIG_WQ_WATCHDOG is configured, workqueue can
			warn stall conditions and dump internal state to
			help debugging.  0 disables workqueue stall
			detection; otherwise, it's the stall threshold
			duration in seconds.  The default value is 30 and
			it can be updated at runtime by writing to the
			corresponding sysfs file.

	workqueue.disable_numa
			By default, all work items queued to unbound
			workqueues are affine to the NUMA nodes they're
			issued on, which results in better behavior in
			general.  If NUMA affinity needs to be disabled for
			whatever reason, this option can be used.  Note
			that this also can be controlled per-workqueue for
			workqueues visible under /sys/bus/workqueue/.

	workqueue.power_efficient
			Per-cpu workqueues are generally preferred because
			they show better performance thanks to cache
			locality; unfortunately, per-cpu workqueues tend to
			be more power hungry than unbound workqueues.

			Enabling this makes the per-cpu workqueues which
			were observed to contribute significantly to power
			consumption unbound, leading to measurably lower
			power usage at the cost of small performance
			overhead.

			The default value of this parameter is determined by
			the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.

	workqueue.debug_force_rr_cpu
			Workqueue used to implicitly guarantee that work
			items queued without explicit CPU specified are put
			on the local CPU.  This guarantee is no longer true
			and while local CPU is still preferred work items
			may be put on foreign CPUs.  This debug option
			forces round-robin CPU selection to flush out
			usages which depend on the now broken guarantee.
			When enabled, memory and cache locality will be
			impacted.

	x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
			default x2apic cluster mode on platforms
			supporting x2apic.

	x86_intel_mid_timer= [X86-32,APBT]
			Choose timer option for x86 Intel MID platform.
			Two valid options are apbt timer only and lapic timer
			plus one apbt timer for broadcast timer.
			x86_intel_mid_timer=apbt_only | lapic_and_apbt

	xen_512gb_limit		[KNL,X86-64,XEN]
			Restricts the kernel running paravirtualized under Xen
			to use only up to 512 GB of RAM. The reason to do so is
			crash analysis tools and Xen tools for doing domain
			save/restore/migration must be enabled to handle larger
			domains.

	xen_emul_unplug=		[HW,X86,XEN]
			Unplug Xen emulated devices
			Format: [unplug0,][unplug1]
			ide-disks -- unplug primary master IDE devices
			aux-ide-disks -- unplug non-primary-master IDE devices
			nics -- unplug network devices
			all -- unplug all emulated devices (NICs and IDE disks)
			unnecessary -- unplugging emulated devices is
				unnecessary even if the host did not respond to
				the unplug protocol
			never -- do not unplug even if version check succeeds

	xen_legacy_crash	[X86,XEN]
			Crash from Xen panic notifier, without executing late
			panic() code such as dumping handler.

	xen_nopvspin	[X86,XEN]
			Disables the qspinlock slowpath using Xen PV optimizations.
			This parameter is obsoleted by "nopvspin" parameter, which
			has equivalent effect for XEN platform.

	xen_nopv	[X86]
			Disables the PV optimizations forcing the HVM guest to
			run as generic HVM guest with no PV drivers.
			This option is obsoleted by the "nopv" option, which
			has equivalent effect for XEN platform.

	xen_scrub_pages=	[XEN]
			Boolean option to control scrubbing pages before giving them back
			to Xen, for use by other domains. Can be also changed at runtime
			with /sys/devices/system/xen_memory/xen_memory0/scrub_pages.
			Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.

	xen_timer_slop=	[X86-64,XEN]
			Set the timer slop (in nanoseconds) for the virtual Xen
			timers (default is 100000). This adjusts the minimum
			delta of virtualized Xen timers, where lower values
			improve timer resolution at the expense of processing
			more timer interrupts.

	xen.event_eoi_delay=	[XEN]
			How long to delay EOI handling in case of event
			storms (jiffies). Default is 10.

	xen.event_loop_timeout=	[XEN]
			After which time (jiffies) the event handling loop
			should start to delay EOI handling. Default is 2.

	xen.fifo_events=	[XEN]
			Boolean parameter to disable using fifo event handling
			even if available. Normally fifo event handling is
			preferred over the 2-level event handling, as it is
			fairer and the number of possible event channels is
			much higher. Default is on (use fifo events).

	nopv=		[X86,XEN,KVM,HYPER_V,VMWARE]
			Disables the PV optimizations forcing the guest to run
			as generic guest with no PV drivers. Currently support
			XEN HVM, KVM, HYPER_V and VMWARE guest.

	nopvspin	[X86,XEN,KVM]
			Disables the qspinlock slow path using PV optimizations
			which allow the hypervisor to 'idle' the guest on lock
			contention.

	xirc2ps_cs=	[NET,PCMCIA]
			Format:
			<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]

	xive=		[PPC]
			By default on POWER9 and above, the kernel will
			natively use the XIVE interrupt controller. This option
			allows the fallback firmware mode to be used:

			off       Fallback to firmware control of XIVE interrupt
				  controller on both pseries and powernv
				  platforms. Only useful on POWER9 and above.

	xhci-hcd.quirks		[USB,KNL]
			A hex value specifying bitmask with supplemental xhci
			host controller quirks. Meaning of each bit can be
			consulted in header drivers/usb/host/xhci.h.

	xmon		[PPC]
			Format: { early | on | rw | ro | off }
			Controls if xmon debugger is enabled. Default is off.
			Passing only "xmon" is equivalent to "xmon=early".
			early	Call xmon as early as possible on boot; xmon
				debugger is called from setup_arch().
			on	xmon debugger hooks will be installed so xmon
				is only called on a kernel crash. Default mode,
				i.e. either "ro" or "rw" mode, is controlled
				with CONFIG_XMON_DEFAULT_RO_MODE.
			rw	xmon debugger hooks will be installed so xmon
				is called only on a kernel crash, mode is write,
				meaning SPR registers, memory and, other data
				can be written using xmon commands.
			ro 	same as "rw" option above but SPR registers,
				memory, and other data can't be written using
				xmon commands.
			off	xmon is disabled.