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.txt, 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]
		acpi_backlight=vendor
		acpi_backlight=video
		If set to vendor, prefer vendor specific driver
		(e.g. thinkpad_acpi, sony_acpi, etc.) instead
		of the ACPI video.ko driver.

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/acpi/debug.txt 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: <int>

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_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.txt 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/alsa-parameters.txt

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 whilst 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.txt.

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" } (0 = disabled, 1 = enabled)
		0 - 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 - 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.txt

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

bootmem_debug	[KNL] Enable bootmem allocator debug messages.

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

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/media/v4l-drivers/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.

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/CommonIO 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 one, multiple, all cgroup controllers in v1
		Format: { controller[,controller...] | "all" }
		Like cgroup_disable, but only applies to cgroup v1;
		the blacklisted controllers remain available in cgroup2.

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
			/selinux/checkreqprot.

cio_ignore=	[S390]
		See Documentation/s390/CommonIO 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/clk.txt.

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 [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]]]
		[ARM,X86,KNL]
		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
		include/linux/dma-contiguous.h

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.

code_bytes	[X86] How many bytes of object code to print
		in an oops report.
		Range: 0 - 8192
		Default: 64

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.txt 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.txt.

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

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

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. Check
		Documentation/kdump/kdump.txt 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/kdump/kdump.txt 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_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. In
		default, it is disabled. We can avoid allocating huge
		chunk of memory for debug pagealloc if we don't enable
		it at boot time and the system will work mostly same
		with the kernel built without CONFIG_DEBUG_PAGEALLOC.
		on: enable the feature

debugpat	[X86] Enable PAT debugging

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

default_hugepagesz=
		[same as hugepagesz=] The size of the default
		HugeTLB page size. This is the size represented by
		the legacy /proc/ hugepages APIs, used for SHM, and
		default size when mounting hugetlbfs filesystems.
		Defaults to the default architecture's huge page size
		if not specified.

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.

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

disable_radix	[PPC]
		Disable RADIX MMU mode on POWER9

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.

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

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

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.

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/EDID/HOWTO.txt. 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.

nompx		[X86] Disables Intel Memory Protection Extensions.
		See Documentation/x86/intel_mpx.txt for more
		information about the feature.

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 the stdout-path property in device
		tree's chosen node.

	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.

	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.

	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.

earlyprintk=	[X86,SH,BLACKFIN,ARM,M68k,S390]
		earlyprintk=vga
		earlyprintk=efi
		earlyprintk=sclp
		earlyprintk=xen
		earlyprintk=serial[,ttySn[,baudrate]]
		earlyprintk=serial[,0x...[,baudrate]]
		earlyprintk=ttySn[,baudrate]
		earlyprintk=dbgp[debugController#]
		earlyprintk=pciserial,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.

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

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

efi=		[EFI]
		Format: { "old_map", "nochunk", "noruntime", "debug" }
		old_map [X86-64]: switch to the old ioremap-based EFI
		runtime services mapping. 32-bit still uses this one by
		default.
		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
		debug: enable misc debug output

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.

		Using this parameter you can do debugging of EFI memmap
		related feature. For example, you can do debugging of
		Address Range Mirroring feature even if your box
		doesn't support it.

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/acpi/ssdt-overlays.txt 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.

elevator=	[IOSCHED]
		Format: {"cfq" | "deadline" | "noop"}
		See Documentation/block/cfq-iosched.txt and
		Documentation/block/deadline-iosched.txt for details.

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

floppy=		[HW]
		See Documentation/blockdev/floppy.txt.

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)

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: <integer>

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"

hisax=		[HW,ISDN]
		See Documentation/isdn/README.HiSax.

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.

hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
		On x86-64 and powerpc, this option can be specified
		multiple times interleaved with hugepages= to reserve
		huge pages of different sizes. Valid pages sizes on
		x86-64 are 2M (when the CPU supports "pse") and 1G
		(when the CPU supports the "pdpe1gb" cpuinfo flag).

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.

hwthread_map=	[METAG] Comma-separated list of Linux cpu id to
		        hardware thread id mappings.
			Format: <cpu>:<hwthread>

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.txt.

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]
		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"

		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. (This is the equivalent
		of ima_appraise_tcb.)

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

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

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.
	ecs_off [Default Off]
		By default, extended context tables will be supported if
		the hardware advertises that it has support both for the
		extended tables themselves, and also PASID support. With
		this option set, extended tables will not be used even
		on hardware which claims to support them.
	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.

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
	forcesac
	soft
	pt		[x86, IA-64]
	nobypass	[PPC/POWERNV]
		Disable IOMMU bypass, using IOMMU for PCI devices.

iommu.passthrough=
		[ARM64] 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 IOMMU translation for DMA.

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/filesystems/nfs/nfsroot.txt.

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.

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.
		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".

		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] | "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. The
		remaining memory in each node is used for Movable
		pages. In the event, a node is too small to have both
		kernelcore and Movable pages, kernelcore pages will
		take priority and other nodes will have a larger number
		of Movable pages.  The Movable zone is used for the
		allocation of pages that may be reclaimed or moved
		by the page migration subsystem.  This means that
		HugeTLB pages may not be allocated from this zone.
		Note that allocations like PTEs-from-HighMem still
		use the HighMem zone if it exists, and the Normal
		zone if it does not.

		Instead of specifying the amount of memory (nn[KMGTPE]),
		you can specify "mirror" option. In case "mirror"
		option is specified, mirrored (reliable) memory is used
		for non-movable allocations and remaining memory is used
		for Movable pages. nn[KMGTPE] and "mirror" are exclusive,
		so you can NOT specify nn[KMGTPE] and "mirror" at the same
		time.

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]

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.

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

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

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

l2cr=		[PPC]

l3cr=		[PPC]

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

lapic=		[x86,APIC] "notscdeadline" Do not use TSC deadline
		value for LAPIC timer one-shot implementation. Default
		back to the programmable timer unit in the LAPIC.

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] List of ramdisks to load from floppy
		See Documentation/blockdev/ramdisk.txt.

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>

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>

machvec=	[IA-64] Force the use of a particular machine-vector
		(machvec) in a generic kernel.
		Example: machvec=hpzx1_swiotlb

machtype=	[Loongson] Share the same kernel image file between different
		 yeeloong laptop.
		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.txt

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.

mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
		Amount of memory to be used when the kernel is not able
		to see the whole system memory or for test.
		[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.

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/memory-hotplug.txt.

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.

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] 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/x86/amd-memory-encryption.txt
		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/media/v4l-drivers/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
		http://repo.or.cz/w/linux-2.6/mini2440.git

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=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
		is similar to kernelcore except 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/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/filesystems/nfs/nfsroot.txt.

nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
		See Documentation/filesystems/nfs/nfsroot.txt.

nfsrootdebug	[NFS] enable nfsroot debugging messages.
		See Documentation/filesystems/nfs/nfsroot.txt.

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_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 override the opposite
		default). 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.

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.

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]
		Disable SMAP (Supervisor Mode Access Prevention)
		even if it is supported by processor.

nosmep		[X86]
		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] Disable kernel huge I/O mappings.

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

nospectre_v2	[X86] Disable all mitigations for the Spectre variant 2
		(indirect branch prediction) vulnerability. System may
		allow data leaks with this option, which is equivalent
		to spectre_v2=off.

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,KVM] 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-paravirt	[X86,IA-64,PV_OPS] Don't patch paravirt_ops

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.

notsc		[BUGS=X86-32] Disable Time Stamp Counter

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/sysctl/vm.txt for details.

ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
		See Documentation/debugging-via-ohci1394.txt 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.

OSS		[HW,OSS]
		See Documentation/sound/oss/oss-parameters.txt

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.
		off: turn off poisoning
		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_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/blockdev/paride.txt.

pci=option[,option...]	[PCI] various PCI subsystem options:
	earlydump	[X86] 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>@][<domain>:]<bus>:<slot>.<func>[; ...]
			[<order of align>@]pci:<vendor>:<device>\
					[:<subvendor>:<subdevice>][; ...]
			Specifies alignment and device to reassign
			aligned memory resources.
			If <order of align> is not specified,
			PAGE_SIZE is used as alignment.
			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., 4096@pci:8086:9c22:103c:198f
	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.
	hpmemsize=nn[KMG]	The fixed amount of bus space which is
			reserved for hotplug bridge's memory 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.
	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.

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_hp=	[PCIE] PCI Express Hotplug driver options:
	nomsi	Do not use MSI for PCI Express Native Hotplug (this
		makes all PCIe ports use INTx for hotplug services).

pcie_ports=	[PCIE] PCIe ports handling:
	auto	Ask the BIOS whether or not to use native PCIe services
		associated with PCIe ports (PME, hot-plug, AER).  Use
		them only if that is allowed by the BIOS.
	native	Use native PCIe services associated with PCIe ports
		unconditionally.
	compat	Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
		ports driver.

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/blockdev/paride.txt.

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/blockdev/paride.txt.

pg.		[PARIDE]
		See Documentation/blockdev/paride.txt.

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

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

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] List of RAM disks to prompt for floppy disk
		before loading.
		See Documentation/blockdev/ramdisk.txt.

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/blockdev/paride.txt.

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/blockdev/ramdisk.txt.

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.

		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 "b" for RCU-bh, "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.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.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().

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.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_leader_stride= [KNL]
		Set the number of NOCB kthread groups, which
		defaults to the square root of the number of
		CPUs.  Larger numbers reduces the wakeup overhead
		on the per-CPU grace-period kthreads, but increases
		that same overhead on each group's leader.

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.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().

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

rcuperf.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.

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

rcuperf.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.

rcuperf.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.

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

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

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

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

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

rcutorture.cbflood_inter_holdoff= [KNL]
		Set holdoff time (jiffies) between successive
		callback-flood tests.

rcutorture.cbflood_intra_holdoff= [KNL]
		Set holdoff time (jiffies) between successive
		bursts of callbacks within a given callback-flood
		test.

rcutorture.cbflood_n_burst= [KNL]
		Set the number of bursts making up a given
		callback-flood test.  Set this to zero to
		disable callback-flood testing.

rcutorture.cbflood_n_per_burst= [KNL]
		Set the number of callbacks to be registered
		in a given burst of a callback-flood test.

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.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.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 (s) between CPU-hotplug operations, or
		zero to disable CPU-hotplug testing.

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

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

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_suppress= [KNL]
		Suppress RCU CPU stall warning messages.

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_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

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

rcupdate.rcu_self_test_sched= [KNL]
		Run the RCU sched 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.

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,
		      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.

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

reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area

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.txt

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.

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 security module to enable at boot.
		If this boot parameter is not specified, only the first
		security module asking for security registration will be
		loaded. An invalid security module name will be treated
		as if no module has been chosen.

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 set via kernel config option.
		If enabled at boot time, /selinux/disable can be used
		later to disable prior to initial policy load.

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.txt.

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]]	[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.txt.

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.txt.

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.txt.

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.txt.

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: <integer>

		A nonzero value instructs the soft-lockup detector
		to panic the machine when a soft-lockup occurs. This
		is also controlled by 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: <integer>

sonypi.*=	[HW] Sony Programmable I/O Control Device driver
		See Documentation/laptops/sonypi.txt

spectre_v2=	[X86] Control mitigation of Spectre variant 2
		(indirect branch speculation) vulnerability.

		on   - unconditionally enable
		off  - unconditionally disable
		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.

		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.

spia_io_base=	[HW,MTD]
spia_fio_base=
spia_pedr=
spia_peddr=

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.

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.

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/cgroup-v1/memory.txt)

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]

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.txt
		"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.

tmem		[KNL,XEN]
		Enable the Transcendent memory driver if built-in.

tmem.cleancache=0|1 [KNL, XEN]
		Default is on (1). Disable the usage of the cleancache
		API to send anonymous pages to the hypervisor.

tmem.frontswap=0|1 [KNL, XEN]
		Default is on (1). Disable the usage of the frontswap
		API to send swap pages to the hypervisor. If disabled
		the selfballooning and selfshrinking are force disabled.

tmem.selfballooning=0|1 [KNL, XEN]
		Default is on (1). Disable the driving of swap pages
		to the hypervisor.

tmem.selfshrinking=0|1 [KNL, XEN]
		Default is on (1). Partial swapoff that immediately
		transfers pages from Xen hypervisor back to the
		kernel based on different criteria.

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.

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.txt

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.txt "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/vm/transhuge.txt 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.

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)

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

usbhid.mousepoll=
		[USBHID] The interval which mice are to be polled at.

usbhid.jspoll=
		[USBHID] The interval which joysticks 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);
			b = BAD_SENSE (don't collect more than 18
				bytes of sense data);
			c = FIX_CAPACITY (decrease the reported
				device capacity by one sector);
			d = NO_READ_DISC_INFO (don't use
				READ_DISC_INFO command);
			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);
			m = MAX_SECTORS_64 (don't transfer more
				than 64 sectors = 32 KB at a time);
			n = INITIAL_READ10 (force a retry of the
				initial READ(10) command);
			o = CAPACITY_OK (accept the capacity
				reported by the device);
			p = WRITE_CACHE (the device cache is ON
				by default);
			r = IGNORE_RESIDUE (the device reports
				bogus residue values);
			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)
		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.txt.

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.txt and
		Documentation/svga.txt.
		Use vga=ask for menu.
		This is actually a boot loader parameter; the value is
		passed to the kernel using a special protocol.

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.

		native      Vsyscalls are native syscall instructions.
		            This is a little bit faster than trapping
		            and makes a few dynamic recompilers work
		            better than they would in emulation mode.
		            It also makes exploits much easier to write.

		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.txt
		or other driver-specific files in the
		Documentation/watchdog/ directory.

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_nopvspin	[X86,XEN]
		Disables the ticketlock slowpath using Xen PV
		optimizations.

xen_nopv	[X86]
		Disables the PV optimizations forcing the HVM guest to
		run as generic HVM guest with no PV drivers.

xirc2ps_cs=	[NET,PCMCIA]
		Format:
		<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]