Merge tag 'docs-5.19' of git://git.lwn.net/linux

  io.latency

	This takes a similar format as the other controllers.

		"MAJOR:MINOR target=<target time in microseconds"

		"MAJOR:MINOR target=<target time in microseconds>"

  io.stat

	If the controller is enabled you will see extra stats in io.stat in

	ALSA	ALSA sound support is enabled.

	APIC	APIC support is enabled.

	APM	Advanced Power Management support is enabled.

	APPARMOR AppArmor support is enabled.

	ARM	ARM architecture is enabled.

	ARM64	ARM64 architecture is enabled.

	AX25	Appropriate AX.25 support is enabled.

	DYNAMIC_DEBUG Build in debug messages and enable them at runtime

	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled

	EFI	EFI Partitioning (GPT) is enabled

	EIDE	EIDE/ATAPI support is enabled.

	EVM	Extended Verification Module

	FB	The frame buffer device is enabled.

	FTRACE	Function tracing enabled.

	GCOV	GCOV profiling is enabled.

	HIBERNATION HIBERNATION is enabled.

	HW	Appropriate hardware is enabled.

	HYPER_V HYPERV support is enabled.

	IA-64	IA-64 architecture is enabled.

	IMA     Integrity measurement architecture is enabled.

	IOSCHED	More than one I/O scheduler is enabled.

	IP_PNP	IP DHCP, BOOTP, or RARP is enabled.

	IPV6	IPv6 support is enabled.

	ISAPNP	ISA PnP code is enabled.

	NUMA	NUMA support is enabled.

	NFS	Appropriate NFS support is enabled.

	OF	Devicetree is enabled.

	OSS	OSS sound support is enabled.

	PV_OPS	A paravirtualized kernel is enabled.

	PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.

	PARISC	The PA-RISC architecture is enabled.

			the Documentation/scsi/ sub-directory.

	SECURITY Different security models are enabled.

	SELINUX SELinux support is enabled.

	APPARMOR AppArmor support is enabled.

	SERIAL	Serial support is enabled.

	SH	SuperH architecture is enabled.

	SMP	The kernel is an SMP kernel.

	SWSUSP	Software suspend (hibernation) is enabled.

	SUSPEND	System suspend states are enabled.

	TPM	TPM drivers are enabled.

	TS	Appropriate touchscreen support is enabled.

	UMS	USB Mass Storage support is enabled.

	USB	USB support is enabled.

	USBHID	USB Human Interface Device support is enabled.

	VGA	The VGA console has been enabled.

	VT	Virtual terminal support is enabled.

	WDT	Watchdog support is enabled.

	XT	IBM PC/XT MFM hard disk support is enabled.

	X86-32	X86-32, aka i386 architecture is enabled.

	X86-64	X86-64 architecture is enabled.

			More X86-64 boot options can be found in

complete command line (parameters including spaces etc.) is limited to

a fixed number of characters. This limit depends on the architecture

and is between 256 and 4096 characters. It is defined in the file

./include/asm/setup.h as COMMAND_LINE_SIZE.

./include/uapi/asm-generic/setup.h as COMMAND_LINE_SIZE.

Finally, the [KMG] suffix is commonly described after a number of kernel

parameter values. These 'K', 'M', and 'G' letters represent the _binary_

			Format: <io>,<irq>,<mode>

			See header of drivers/net/hamradio/baycom_ser_hdx.c.

	bert_disable	[ACPI]

			Disable BERT OS support on buggy BIOSes.

	bgrt_disable	[ACPI][X86]

			Disable BGRT to avoid flickering OEM logo.

	blkdevparts=	Manual partition parsing of block device(s) for

			embedded devices based on command line input.

			See Documentation/block/cmdline-partition.rst

			See Documentation/admin-guide/bootconfig.rst

	bert_disable	[ACPI]

			Disable BERT OS support on buggy BIOSes.

	bgrt_disable	[ACPI][X86]

			Disable BGRT to avoid flickering OEM logo.

	bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)

	bttv.radio=	Most important insmod options are available as

			kernel args too.

	cio_ignore=	[S390]

			See Documentation/s390/common_io.rst for details.

	clearcpuid=X[,X...] [X86]

			Disable CPUID feature X for the kernel. See

			arch/x86/include/asm/cpufeatures.h for the valid bit

			numbers X. Note the Linux-specific bits are not necessarily

			stable over kernel options, but the vendor-specific

			ones should be.

			X can also be a string as appearing in the flags: line

			in /proc/cpuinfo which does not have the above

			instability issue. However, not all features have names

			in /proc/cpuinfo.

			Note that using this option will taint your kernel.

			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.

	clk_ignore_unused

			[CLK]

			Prevents the clock framework from automatically gating

			Defaults to zero when built as a module and to

			10 seconds when built into the kernel.

	clearcpuid=X[,X...] [X86]

			Disable CPUID feature X for the kernel. See

			arch/x86/include/asm/cpufeatures.h for the valid bit

			numbers X. Note the Linux-specific bits are not necessarily

			stable over kernel options, but the vendor-specific

			ones should be.

			X can also be a string as appearing in the flags: line

			in /proc/cpuinfo which does not have the above

			instability issue. However, not all features have names

			in /proc/cpuinfo.

			Note that using this option will taint your kernel.

			Also note that user programs calling CPUID directly

			or using the feature without checking anything

			will still see it. This just prevents it from

			being used by the kernel or shown in /proc/cpuinfo.

			Also note the kernel might malfunction if you disable

			some critical bits.

	cma=nn[MG]@[start[MG][-end[MG]]]

			[KNL,CMA]

			Sets the size of kernel global memory area for

			0: default value, disable debugging

			1: enable debugging at boot time

	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver

			Format:

			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

	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.

	cpuidle.off=1	[CPU_IDLE]

			disable the cpuidle sub-system

			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>]

	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.

	crashkernel=size[KMG][@offset[KMG]]

			[KNL] Using kexec, Linux can switch to a 'crash kernel'

			dump out devices still on the deferred probe list after

			retrying.

	delayacct	[KNL] Enable per-task delay accounting

	dell_smm_hwmon.ignore_dmi=

			[HW] Continue probing hardware even if DMI data

			indicates that the driver is running on unsupported

	disable=	[IPV6]

			See Documentation/networking/ipv6.rst.

	hardened_usercopy=

                        [KNL] Under CONFIG_HARDENED_USERCOPY, whether

                        hardening is enabled for this boot. Hardened

                        usercopy checking is used to protect the kernel

                        from reading or writing beyond known memory

                        allocation boundaries as a proactive defense

                        against bounds-checking flaws in the kernel's

                        copy_to_user()/copy_from_user() interface.

                on      Perform hardened usercopy checks (default).

                off     Disable hardened usercopy checks.

	disable_radix	[PPC]

			Disable RADIX MMU mode on POWER9

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

			takes over.

			Only one of vga, efi, serial, or usb debug port can

			Only one of vga, serial, or usb debug port can

			be used at a time.

			Currently only ttyS0 and ttyS1 may be specified by

			Interaction with the standard serial driver is not

			very good.

			The VGA and EFI output is eventually overwritten by

			The VGA output is eventually overwritten by

			the real console.

			The xen option can only be used in Xen domains.

			force: enforce the use of EDAC to report H/W event.

			default: on.

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

			ekgdboc=kbd

			This is designed to be used in conjunction with

			the boot argument: earlyprintk=vga

			This parameter works in place of the kgdboc parameter

			but can only be used if the backing tty is available

			very early in the boot process. For early debugging

			via a serial port see kgdboc_earlycon instead.

	edd=		[EDD]

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

	eisa_irq_edge=	[PARISC,HW]

			See header of drivers/parisc/eisa.c.

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

			Format: ekgdboc=kbd

			This is designed to be used in conjunction with

			the boot argument: earlyprintk=vga

			This parameter works in place of the kgdboc parameter

			but can only be used if the backing tty is available

			very early in the boot process. For early debugging

			via a serial port see kgdboc_earlycon instead.

	elanfreq=	[X86-32]

			See comment before function elanfreq_setup() in

			arch/x86/kernel/cpu/cpufreq/elanfreq.c.

			Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.

			Default: 1024

	hardened_usercopy=

			[KNL] Under CONFIG_HARDENED_USERCOPY, whether

			hardening is enabled for this boot. Hardened

			usercopy checking is used to protect the kernel

			from reading or writing beyond known memory

			allocation boundaries as a proactive defense

			against bounds-checking flaws in the kernel's

			copy_to_user()/copy_from_user() interface.

		on	Perform hardened usercopy checks (default).

		off	Disable hardened usercopy checks.

	hardlockup_all_cpu_backtrace=

			[KNL] Should the hard-lockup detector generate

			backtraces on all cpus.

			corresponding firmware-first mode error processing

			logic will be disabled.

	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).

	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

	hpet_mmap=	[X86, HPET_MMAP] Allow userspace to mmap HPET

			registers.  Default set by CONFIG_HPET_MMAP_DEFAULT.

	hugetlb_cma=	[HW,CMA] The size of a CMA area used for allocation

			of gigantic hugepages. Or using node format, the size

			of a CMA area per node can be specified.

			Format: nn[KMGTPE] or (node format)

				<node>:nn[KMGTPE][,<node>:nn[KMGTPE]]

			Reserve a CMA area of given size and allocate gigantic

			hugepages using the CMA allocator. If enabled, the

			boot-time allocation of gigantic hugepages is skipped.

	hugepages=	[HW] Number of HugeTLB pages to allocate at boot.

			If this follows hugepagesz (below), it specifies

			the number of pages of hugepagesz to be allocated.

			Documentation/admin-guide/mm/hugetlbpage.rst.

			Format: size[KMG]

	hugetlb_cma=	[HW,CMA] The size of a CMA area used for allocation

			of gigantic hugepages. Or using node format, the size

			of a CMA area per node can be specified.

			Format: nn[KMGTPE] or (node format)

				<node>:nn[KMGTPE][,<node>:nn[KMGTPE]]

			Reserve a CMA area of given size and allocate gigantic

			hugepages using the CMA allocator. If enabled, the

			boot-time allocation of gigantic hugepages is skipped.

	hugetlb_free_vmemmap=

			[KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP

			enabled.

	icn=		[HW,ISDN]

			Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]

	ide-core.nodma=	[HW] (E)IDE subsystem

			Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc

			.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr

			.cdrom .chs .ignore_cable are additional options

			See Documentation/ide/ide.rst.

	ide-generic.probe-mask= [HW] (E)IDE subsystem

			Format: <int>

			Probe mask for legacy ISA IDE ports.  Depending on

			platform up to 6 ports are supported, enabled by

			setting corresponding bits in the mask to 1.  The

			default value is 0x0, which has a special meaning.

			On systems that have PCI, it triggers scanning the

			PCI bus for the first and the second port, which

			are then probed.  On systems without PCI the value

			of 0x0 enables probing the two first ports as if it

			was 0x3.

	ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem

			Claim all unknown PCI IDE storage controllers.

	idle=		[X86]

			Format: idle=poll, idle=halt, idle=nomwait

			If there are multiple matching configurations changing

			the same attribute, the last one is used.

	memblock=debug	[KNL] Enable memblock debug messages.

	load_ramdisk=	[RAM] [Deprecated]

	lockd.nlm_grace_period=P  [NFS] Assign grace period.

			different yeeloong laptops.

			Example: machtype=lemote-yeeloong-2f-7inch

	max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater

	max_addr=nn[KMG]	[KNL,BOOT,IA-64] All physical memory greater

			than or equal to this physical address is ignored.

	maxcpus=	[SMP] Maximum number of processors that	an SMP kernel

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

			memory.

	memblock=debug	[KNL] Enable memblock debug messages.

	memchunk=nn[KMG]

			[KNL,SH] Allow user to override the default size for

			per-device physically contiguous DMA buffers.

	mga=		[HW,DRM]

	min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this

	min_addr=nn[KMG]	[KNL,BOOT,IA-64] All physical memory below this

			physical address is ignored.

	mini2440=	[ARM,HW,KNL]

	mtdparts=	[MTD]

			See drivers/mtd/parsers/cmdlinepart.c

	multitce=off	[PPC]  This parameter disables the use of the pSeries

			firmware feature for updating multiple TCE entries

			at a time.

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

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

			boundary - index of last SLC block on Flex-OneNAND.

				   The remaining blocks are configured as MLC blocks.

			lock	 - Configure if Flex-OneNAND boundary should be locked.

				   Once locked, the boundary cannot be changed.

				   1 indicates lock status, 0 indicates unlock status.

	mtdset=		[ARM]

			ARM/S3C2412 JIVE boot control

			Used for mtrr cleanup. It is spare mtrr entries number.

			Set to 2 or more if your graphical card needs more.

	multitce=off	[PPC]  This parameter disables the use of the pSeries

			firmware feature for updating multiple TCE entries

			at a time.

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

	netdev=		[NET] Network devices parameters

			This usage is only documented in each driver source

			file if at all.

	netpoll.carrier_timeout=

			[NET] Specifies amount of time (in seconds) that

			netpoll should wait for a carrier. By default netpoll

			waits 4 seconds.

	nf_conntrack.acct=

			[NETFILTER] Enable connection tracking flow accounting

			0 to disable accounting

			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.

	nocache		[ARM]

	delayacct	[KNL] Enable per-task delay accounting

	nodsp		[SH] Disable hardware DSP at boot time.

	noefi		Disable EFI runtime services support.

	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

			For example, to override I2C bus2:

			omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100

	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.

	oops=panic	Always panic on oopses. Default is to just kill the

			process, but there is a small probability of

			deadlocking the machine.

	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#>

			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=

				1: Fast pin select (default)

				2: ATC IRMode

	smt		[KNL,S390] Set the maximum number of threads (logical

	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.

			This parameter controls use of the Protected

			Execution Facility on pSeries.

	swapaccount=[0|1]

			[KNL] Enable accounting of swap in memory resource

	swapaccount=	[KNL]

			Format: [0|1]

			Enable accounting of swap in memory resource

			controller if no parameter or 1 is given or disable

			it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)

	tdfx=		[HW,DRM]

	test_suspend=	[SUSPEND][,N]

	test_suspend=	[SUSPEND]

			Format: { "mem" | "standby" | "freeze" }[,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

			This will guarantee that all the other pcrs

			are saved.

	trace_buf_size=nn[KMG]

			[FTRACE] will set tracing buffer size on each cpu.

	trace_event=[event-list]

			[FTRACE] Set and start specified trace events in order

			to facilitate early boot debugging. The event-list is a

			comma-separated list of trace events to enable. See

			also Documentation/trace/events.rst

	trace_options=[option-list]

			[FTRACE] Enable or disable tracer options at boot.

			The option-list is a comma delimited list of options

			that can be enabled or disabled just as if you were

			to echo the option name into

			    /sys/kernel/debug/tracing/trace_options

			For example, to enable stacktrace option (to dump the

			stack trace of each event), add to the command line:

			      trace_options=stacktrace

			See also Documentation/trace/ftrace.rst "trace options"

			section.

	tp_printk	[FTRACE]

			Have the tracepoints sent to printk as well as the

			tracing ring buffer. This is useful for early boot up

			This command line option will stop the printing of events

			to console at the late_initcall_sync() time frame.

	trace_buf_size=nn[KMG]

			[FTRACE] will set tracing buffer size on each cpu.

	trace_clock=	[FTRACE] Set the clock used for tracing events

			at boot up.

			local - Use the per CPU time stamp counter

				(converted into nanoseconds). Fast, but

				depending on the architecture, may not be

				in sync between CPUs.

			global - Event time stamps are synchronize across

				CPUs. May be slower than the local clock,

				but better for some race conditions.

			counter - Simple counting of events (1, 2, ..)

				note, some counts may be skipped due to the

				infrastructure grabbing the clock more than

				once per event.

			uptime - Use jiffies as the time stamp.

			perf - Use the same clock that perf uses.

			mono - Use ktime_get_mono_fast_ns() for time stamps.

			mono_raw - Use ktime_get_raw_fast_ns() for time

				stamps.

			boot - Use ktime_get_boot_fast_ns() for time stamps.

			Architectures may add more clocks. See

			Documentation/trace/ftrace.rst for more details.

	trace_event=[event-list]

			[FTRACE] Set and start specified trace events in order

			to facilitate early boot debugging. The event-list is a

			comma-separated list of trace events to enable. See

			also Documentation/trace/events.rst

	trace_options=[option-list]

			[FTRACE] Enable or disable tracer options at boot.

			The option-list is a comma delimited list of options

			that can be enabled or disabled just as if you were

			to echo the option name into

			    /sys/kernel/debug/tracing/trace_options

			For example, to enable stacktrace option (to dump the

			stack trace of each event), add to the command line:

			      trace_options=stacktrace

			See also Documentation/trace/ftrace.rst "trace options"

			section.

	traceoff_on_warning

			[FTRACE] enable this option to disable tracing when a

			warning is hit. This turns off "tracing_on". Tracing can

					HIGHMEM regardless of setting

					of CONFIG_HIGHPTE.

	vdso=		[X86,SH]

	vdso=		[X86,SH,SPARC]

			On X86_32, this is an alias for vdso32=.  Otherwise:

			vdso=1: enable VDSO (the default)

	video=		[FB] Frame buffer configuration

			See Documentation/fb/modedb.rst.

	video.brightness_switch_enabled= [0,1]

	video.brightness_switch_enabled= [ACPI]

			Format: [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

			the allocated input device. If set to 0, video driver

			will only send out the event without touching backlight

			brightness level.

			default: 1

1 panic() after printing RCU stall messages.

= ============================================================

max_rcu_stall_to_panic

======================

When ``panic_on_rcu_stall`` is set to 1, this value determines the

number of times that RCU can stall before panic() is called.

When ``panic_on_rcu_stall`` is set to 0, this value is has no effect.

perf_cpu_time_max_percent

=========================