From a5969cabbb4660eab42b6ef0412cbbd1200cf14d Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Sat, 12 Oct 2024 07:10:09 +0000
Subject: [PATCH] 修改led为gpio
---
kernel/Documentation/admin-guide/kernel-parameters.txt | 1554 ++++++++++++++++++++++++++++++++++++++++++++++++-----------
1 files changed, 1,262 insertions(+), 292 deletions(-)
diff --git a/kernel/Documentation/admin-guide/kernel-parameters.txt b/kernel/Documentation/admin-guide/kernel-parameters.txt
index ee76139..c505b06 100644
--- a/kernel/Documentation/admin-guide/kernel-parameters.txt
+++ b/kernel/Documentation/admin-guide/kernel-parameters.txt
@@ -13,7 +13,7 @@
For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force"
are available
- See also Documentation/power/runtime_pm.txt, pci=noacpi
+ See also Documentation/power/runtime_pm.rst, pci=noacpi
acpi_apic_instance= [ACPI, IOAPIC]
Format: <int>
@@ -22,11 +22,13 @@
default: 0
acpi_backlight= [HW,ACPI]
- acpi_backlight=vendor
- acpi_backlight=video
- If set to vendor, prefer vendor specific driver
+ { vendor | video | native | none }
+ If set to vendor, prefer vendor-specific driver
(e.g. thinkpad_acpi, sony_acpi, etc.) instead
of the ACPI video.ko driver.
+ If set to video, use the ACPI video.ko driver.
+ If set to native, use the device's native backlight mode.
+ If set to none, disable the ACPI backlight interface.
acpi_force_32bit_fadt_addr
force FADT to use 32 bit addresses rather than the
@@ -53,7 +55,7 @@
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
+ Documentation/firmware-guide/acpi/debug.rst for more information about
debug layers and levels.
Enable processor driver info messages:
@@ -227,7 +229,7 @@
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
+ See Documentation/power/video.rst for information on
s3_bios and s3_mode.
s3_beep is for debugging; it makes the PC's speaker beep
as soon as the kernel's real-mode entry point is called.
@@ -287,6 +289,20 @@
do not want to use tracing_snapshot_alloc() as it needs
to be done where GFP_KERNEL allocations are allowed.
+ allow_file_spec_access
+ Allow speculative faults on file backed pages.
+ Speculative faults are enabled only for those vm_ops
+ that implement and return true for allow_speculation
+ callback.
+
+ allow_mismatched_32bit_el0 [ARM64]
+ Allow execve() of 32-bit applications and setting of the
+ PER_LINUX32 personality on systems where only a strict
+ subset of the CPUs support 32-bit EL0. When this
+ parameter is present, the set of CPUs supporting 32-bit
+ EL0 is indicated by /sys/devices/system/cpu/aarch32_el0
+ and hot-unplug operations may be restricted.
+
amd_iommu= [HW,X86-64]
Pass parameters to the AMD IOMMU driver in the system.
Possible values are:
@@ -335,7 +351,7 @@
APC and your system crashes randomly.
apic= [APIC,X86] Advanced Programmable Interrupt Controller
- Change the output verbosity whilst booting
+ Change the output verbosity while booting
Format: { quiet (default) | verbose | debug }
Change the amount of debugging information output
when initialising the APIC and IO-APIC components.
@@ -354,7 +370,7 @@
shot down by NMI
autoconf= [IPV6]
- See Documentation/networking/ipv6.txt.
+ See Documentation/networking/ipv6.rst.
show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
Limit apic dumping. The parameter defines the maximal
@@ -370,6 +386,15 @@
arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
Format: <io>,<irq>,<nodeID>
+
+ arm64.nobti [ARM64] Unconditionally disable Branch Target
+ Identification support
+
+ arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication
+ support
+
+ arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension
+ support
ataflop= [HW,M68k]
@@ -434,22 +459,29 @@
blkdevparts= Manual partition parsing of block device(s) for
embedded devices based on command line input.
- See Documentation/block/cmdline-partition.txt
+ See Documentation/block/cmdline-partition.rst
boot_delay= Milliseconds to delay each printk during boot.
Values larger than 10 seconds (10000) are changed to
no delay (0).
Format: integer
- bootmem_debug [KNL] Enable bootmem allocator debug messages.
+ bootconfig [KNL]
+ Extended command line options can be added to an initrd
+ and this will cause the kernel to look for it.
+
+ See Documentation/admin-guide/bootconfig.rst
bert_disable [ACPI]
Disable BERT OS support on buggy BIOSes.
+ bgrt_disable [ACPI][X86]
+ Disable BGRT to avoid flickering OEM logo.
+
bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
bttv.radio= Most important insmod options are available as
kernel args too.
- bttv.pll= See Documentation/media/v4l-drivers/bttv.rst
+ bttv.pll= See Documentation/admin-guide/media/bttv.rst
bttv.tuner=
bulk_remove=off [PPC] This parameter disables the use of the pSeries
@@ -465,6 +497,11 @@
possible to determine what the correct size should be.
This option provides an override for these situations.
+ carrier_timeout=
+ [NET] Specifies amount of time (in seconds) that
+ the kernel should wait for a network carrier. By default
+ it waits 120 seconds.
+
ca_keys= [KEYS] This parameter identifies a specific key(s) on
the system trusted keyring to be used for certificate
trust validation.
@@ -477,7 +514,7 @@
others).
ccw_timeout_log [S390]
- See Documentation/s390/CommonIO for details.
+ See Documentation/s390/common_io.rst for details.
cgroup_disable= [KNL] Disable a particular controller or optional feature
Format: {name of the controller(s) or feature(s) to disable}
@@ -517,10 +554,11 @@
1 -- check protection requested by application.
Default value is set via a kernel config option.
Value can be changed at runtime via
- /selinux/checkreqprot.
+ /sys/fs/selinux/checkreqprot.
+ Setting checkreqprot to 1 is deprecated.
cio_ignore= [S390]
- See Documentation/s390/CommonIO for details.
+ See Documentation/s390/common_io.rst for details.
clk_ignore_unused
[CLK]
Prevents the clock framework from automatically gating
@@ -587,13 +625,24 @@
some critical bits.
cma=nn[MG]@[start[MG][-end[MG]]]
- [ARM,X86,KNL]
+ [KNL,CMA]
Sets the size of kernel global memory area for
contiguous memory allocations and optionally the
placement constraint by the physical address range of
memory allocations. A value of 0 disables CMA
altogether. For more information, see
- include/linux/dma-contiguous.h
+ kernel/dma/contiguous.c
+
+ cma_pernuma=nn[MG]
+ [ARM64,KNL]
+ Sets the size of kernel per-numa memory area for
+ contiguous memory allocations. A value of 0 disables
+ per-numa CMA altogether. And If this option is not
+ specificed, the default value is 0.
+ With per-numa CMA enabled, DMA users on node nid will
+ first try to allocate buffer from the pernuma area
+ which is located in node nid, if the allocation fails,
+ they will fallback to the global default memory area.
cmo_free_hint= [PPC] Format: { yes | no }
Specify whether pages are marked as being inactive
@@ -634,7 +683,7 @@
See Documentation/admin-guide/serial-console.rst for more
information. See
- Documentation/networking/netconsole.txt for an
+ Documentation/networking/netconsole.rst for an
alternative.
uart[8250],io,<addr>[,options]
@@ -681,7 +730,7 @@
coredump_filter=
[KNL] Change the default value for
/proc/<pid>/coredump_filter.
- See also Documentation/filesystems/proc.txt.
+ See also Documentation/filesystems/proc.rst.
coresight_cpu_debug.enable
[ARM,ARM64]
@@ -693,8 +742,16 @@
cpuidle.off=1 [CPU_IDLE]
disable the cpuidle sub-system
+ cpuidle.governor=
+ [CPU_IDLE] Name of the cpuidle governor to use.
+
cpufreq.off=1 [CPU_FREQ]
disable the cpufreq sub-system
+
+ cpufreq.default_governor=
+ [CPU_FREQ] Name of the default cpufreq governor or
+ policy to use. This governor must be registered in the
+ kernel before the cpufreq driver probes.
cpu_init_udelay=N
[X86] Delay for N microsec between assert and de-assert
@@ -711,25 +768,28 @@
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.
+ is selected automatically.
+ [KNL, X86-64] Select a region under 4G first, and
+ fall back to reserve region above 4G when '@offset'
+ hasn't been specified.
+ See Documentation/admin-guide/kdump/kdump.rst for further details.
crashkernel=range1:size1[,range2:size2,...][@offset]
[KNL] Same as above, but depends on the memory
in the running system. The syntax of range is
start-[end] where start and end are both
a memory unit (amount[KMG]). See also
- Documentation/kdump/kdump.txt for an example.
+ Documentation/admin-guide/kdump/kdump.rst for an example.
crashkernel=size[KMG],high
- [KNL, x86_64] range could be above 4G. Allow kernel
+ [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
+ [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
@@ -809,27 +869,41 @@
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.
+ [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this parameter
+ enables the feature at boot time. By default, it is
+ disabled and the system will work mostly the same as a
+ kernel built without CONFIG_DEBUG_PAGEALLOC.
+ Note: to get most of debug_pagealloc error reports, it's
+ useful to also enable the page_owner functionality.
on: enable the feature
+
+ debugfs= [KNL] This parameter enables what is exposed to userspace
+ and debugfs internal clients.
+ Format: { on, no-mount, off }
+ on: All functions are enabled.
+ no-mount:
+ Filesystem is not registered but kernel clients can
+ access APIs and a crashkernel can be used to read
+ its content. There is nothing to mount.
+ off: Filesystem is not registered and clients
+ get a -EPERM as result when trying to register files
+ or directories within debugfs.
+ This is equivalent of the runtime functionality if
+ debugfs was not enabled in the kernel at all.
+ Default value is set in build-time with a kernel configuration.
debugpat [X86] Enable PAT debugging
- decnet.addr= [HW,NET]
- Format: <area>[,<node>]
- See also Documentation/networking/decnet.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.
+ [HW] The size of the default HugeTLB page. This is
+ the size represented by the legacy /proc/ hugepages
+ APIs. In addition, this is the default hugetlb size
+ used for shmget(), mmap() and mounting hugetlbfs
+ filesystems. If not specified, defaults to the
+ architecture's default huge page size. Huge page
+ sizes are architecture dependent. See also
+ Documentation/admin-guide/mm/hugetlbpage.rst.
+ Format: size[KMG]
deferred_probe_timeout=
[KNL] Debugging option to set a timeout in seconds for
@@ -840,6 +914,18 @@
dump out devices still on the deferred probe list after
retrying.
+ dfltcc= [HW,S390]
+ Format: { on | off | def_only | inf_only | always }
+ on: s390 zlib hardware support for compression on
+ level 1 and decompression (default)
+ off: No s390 zlib hardware support
+ def_only: s390 zlib hardware support for deflate
+ only (compression on level 1)
+ inf_only: s390 zlib hardware support for inflate
+ only (decompression)
+ always: Same as 'on' but ignores the selected compression
+ level always using hardware support (used for debugging)
+
dhash_entries= [KNL]
Set number of hash buckets for dentry cache.
@@ -849,8 +935,17 @@
can be useful when debugging issues that require an SLB
miss to occur.
+ disable_dma32= [KNL]
+ Dynamically disable ZONE_DMA32 on kernels compiled with
+ CONFIG_ZONE_DMA32=y.
+
+ stress_slb [PPC]
+ Limits the number of kernel SLB entries, and flushes
+ them frequently to increase the rate of SLB faults
+ on kernel addresses.
+
disable= [IPV6]
- See Documentation/networking/ipv6.txt.
+ See Documentation/networking/ipv6.rst.
hardened_usercopy=
[KNL] Under CONFIG_HARDENED_USERCOPY, whether
@@ -866,6 +961,14 @@
disable_radix [PPC]
Disable RADIX MMU mode on POWER9
+ radix_hcall_invalidate=on [PPC/PSERIES]
+ Disable RADIX GTSE feature and use hcall for TLB
+ invalidate.
+
+ disable_tlbie [PPC]
+ Disable TLBIE instruction. Currently does not work
+ with KVM, with HASH MMU, or with coherent accelerators.
+
disable_cpu_apicid= [X86,APIC,SMP]
Format: <int>
The number of initial APIC ID for the
@@ -875,12 +978,18 @@
causing system reset or hang due to sending
INIT from AP to BSP.
+ perf_v4_pmi= [X86,INTEL]
+ Format: <bool>
+ Disable Intel PMU counter freezing feature.
+ The feature only exists starting from
+ Arch Perfmon v4 (Skylake and newer).
+
disable_ddw [PPC/PSERIES]
- Disable Dynamic DMA Window support. Use this if
+ Disable Dynamic DMA Window support. Use this
to workaround buggy firmware.
disable_ipv6= [IPV6]
- See Documentation/networking/ipv6.txt.
+ See Documentation/networking/ipv6.rst.
disable_mtrr_cleanup [X86]
The kernel tries to adjust MTRR layout from continuous
@@ -930,7 +1039,7 @@
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
+ available in Documentation/admin-guide/edid.rst. An EDID
data set will only be used for a particular connector,
if its name and a colon are prepended to the EDID
name. Each connector may use a unique EDID data
@@ -955,19 +1064,15 @@
what data is available or for reverse-engineering.
dyndbg[="val"] [KNL,DYNAMIC_DEBUG]
- module.dyndbg[="val"]
+ <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]
+ <module>.async_probe [KNL]
Enable asynchronous probe on this module.
early_ioremap_debug [KNL]
@@ -977,12 +1082,10 @@
earlycon= [KNL] Output early console device and options.
- [ARM64] The early console is determined by the
- stdout-path property in device tree's chosen node,
- or determined by the ACPI SPCR table.
-
- [X86] When used with no options the early console is
- determined by the ACPI SPCR table.
+ When used with no options, the early console is
+ determined by stdout-path property in device tree's
+ chosen node or the ACPI SPCR table if supported by
+ the platform.
cdns,<addr>[,options]
Start an early, polled-mode console on a Cadence
@@ -1038,6 +1141,16 @@
specified address. The serial port must already be
setup and configured. Options are not yet supported.
+ rda,<addr>
+ Start an early, polled-mode console on a serial port
+ of an RDA Micro SoC, such as RDA8810PL, at the
+ specified address. The serial port must already be
+ setup and configured. Options are not yet supported.
+
+ sbi
+ Use RISC-V SBI (Supervisor Binary Interface) for early
+ console.
+
smh Use ARM semihosting calls for early console.
s3c2410,<addr>
@@ -1065,6 +1178,12 @@
A valid base address must be provided, and the serial
port must already be setup and configured.
+ ec_imx21,<addr>
+ ec_imx6q,<addr>
+ Start an early, polled-mode, output-only console on the
+ Freescale i.MX UART at the specified address. The UART
+ must already be setup and configured.
+
ar3700_uart,<addr>
Start an early, polled-mode console on the
Armada 3700 serial port at the specified
@@ -1077,9 +1196,21 @@
specified address. The serial port must already be
setup and configured. Options are not yet supported.
+ efifb,[options]
+ Start an early, unaccelerated console on the EFI
+ memory mapped framebuffer (if available). On cache
+ coherent non-x86 systems that use system memory for
+ the framebuffer, pass the 'ram' option so that it is
+ mapped with the correct attributes.
+
+ linflex,<addr>
+ Use early console provided by Freescale LINFlexD UART
+ serial driver for NXP S32V234 SoCs. A valid base
+ address must be provided, and the serial port must
+ already be setup and configured.
+
earlyprintk= [X86,SH,ARM,M68k,S390]
earlyprintk=vga
- earlyprintk=efi
earlyprintk=sclp
earlyprintk=xen
earlyprintk=serial[,ttySn[,baudrate]]
@@ -1136,19 +1267,34 @@
This is designed to be used in conjunction with
the boot argument: earlyprintk=vga
+ This parameter works in place of the kgdboc parameter
+ but can only be used if the backing tty is available
+ very early in the boot process. For early debugging
+ via a serial port see kgdboc_earlycon instead.
+
edd= [EDD]
Format: {"off" | "on" | "skip[mbr]"}
efi= [EFI]
- Format: { "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.
+ Format: { "debug", "disable_early_pci_dma",
+ "nochunk", "noruntime", "nosoftreserve",
+ "novamap", "no_disable_early_pci_dma" }
+ debug: enable misc debug output.
+ disable_early_pci_dma: disable the busmaster bit on all
+ PCI bridges while in the EFI boot stub.
nochunk: disable reading files in "chunks" in the EFI
boot stub, as chunking can cause problems with some
firmware implementations.
noruntime : disable EFI runtime services support
- debug: enable misc debug output
+ nosoftreserve: The EFI_MEMORY_SP (Specific Purpose)
+ attribute may cause the kernel to reserve the
+ memory range for a memory mapping driver to
+ claim. Specify efi=nosoftreserve to disable this
+ reservation and treat the memory by its base type
+ (i.e. EFI_CONVENTIONAL_MEMORY / "System RAM").
+ novamap: do not call SetVirtualAddressMap().
+ no_disable_early_pci_dma: Leave the busmaster bit set
+ on all PCI bridges while in the EFI boot stub
efi_no_storage_paranoia [EFI; X86]
Using this parameter you can use more than 50% of
@@ -1161,21 +1307,27 @@
updating original EFI memory map.
Region of memory which aa attribute is added to is
from ss to ss+nn.
+
If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
attribute is added to range 0x100000000-0x180000000 and
0x10a0000000-0x1120000000.
+ If efi_fake_mem=8G@9G:0x40000 is specified, the
+ EFI_MEMORY_SP(0x40000) attribute is added to
+ range 0x240000000-0x43fffffff.
+
Using this parameter you can do debugging of EFI memmap
- related feature. For example, you can do debugging of
+ related features. For example, you can do debugging of
Address Range Mirroring feature even if your box
- doesn't support it.
+ doesn't support it, or mark specific memory as
+ "soft reserved".
efivar_ssdt= [EFI; X86] Name of an EFI variable that contains an SSDT
that is to be dynamically loaded by Linux. If there are
multiple variables with the same name but with different
vendor GUIDs, all of them will be loaded. See
- Documentation/acpi/ssdt-overlays.txt for details.
+ Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
eisa_irq_edge= [PARISC,HW]
@@ -1185,16 +1337,11 @@
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.
+ See Documentation/admin-guide/kdump/kdump.rst for details.
enable_mtrr_cleanup [X86]
The kernel tries to adjust MTRR layout from continuous
@@ -1213,7 +1360,8 @@
0 -- permissive (log only, no denials).
1 -- enforcing (deny and log).
Default value is 0.
- Value can be changed at runtime via /selinux/enforce.
+ Value can be changed at runtime via
+ /sys/fs/selinux/enforce.
erst_disable [ACPI]
Disable Error Record Serialization Table (ERST)
@@ -1229,14 +1377,20 @@
current integrity status.
failslab=
+ fail_usercopy=
fail_page_alloc=
fail_make_request=[KNL]
General fault injection mechanism.
Format: <interval>,<probability>,<space>,<times>
See also Documentation/fault-injection/.
+ fb_tunnels= [NET]
+ Format: { initns | none }
+ See Documentation/admin-guide/sysctl/net.rst for
+ fb_tunnels_only_for_init_ns
+
floppy= [HW]
- See Documentation/blockdev/floppy.txt.
+ See Documentation/admin-guide/blockdev/floppy.rst.
force_pal_cache_flush
[IA-64] Avoid check_sal_cache_flush which may hang on
@@ -1295,6 +1449,29 @@
can be changed at run time by the max_graph_depth file
in the tracefs tracing directory. default: 0 (no limit)
+ fw_devlink= [KNL] Create device links between consumer and supplier
+ devices by scanning the firmware to infer the
+ consumer/supplier relationships. This feature is
+ especially useful when drivers are loaded as modules as
+ it ensures proper ordering of tasks like device probing
+ (suppliers first, then consumers), supplier boot state
+ clean up (only after all consumers have probed),
+ suspend/resume & runtime PM (consumers first, then
+ suppliers).
+ Format: { off | permissive | on | rpm }
+ off -- Don't create device links from firmware info.
+ permissive -- Create device links from firmware info
+ but use it only for ordering boot state clean
+ up (sync_state() calls).
+ on -- Create device links from firmware info and use it
+ to enforce probe and suspend/resume ordering.
+ rpm -- Like "on", but also use to order runtime PM.
+
+ fw_devlink.strict=<bool>
+ [KNL] Treat all inferred dependencies as mandatory
+ dependencies. This only applies for fw_devlink=on|rpm.
+ Format: <bool>
+
gamecon.map[2|3]=
[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
support via parallel port (up to 5 devices per port)
@@ -1303,9 +1480,29 @@
gamma= [HW,DRM]
- gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
+ gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
Format: off | on
default: on
+
+ gather_data_sampling=
+ [X86,INTEL] Control the Gather Data Sampling (GDS)
+ mitigation.
+
+ Gather Data Sampling is a hardware vulnerability which
+ allows unprivileged speculative access to data which was
+ previously stored in vector registers.
+
+ This issue is mitigated by default in updated microcode.
+ The mitigation may have a performance impact but can be
+ disabled. On systems without the microcode mitigation
+ disabling AVX serves as a mitigation.
+
+ force: Disable AVX to mitigate systems without
+ microcode mitigation. No effect if the microcode
+ mitigation is present. Known to cause crashes in
+ userspace with buggy AVX enumeration.
+
+ off: Disable GDS mitigation.
gcov_persist= [GCOV] When non-zero (default), profiling data for
kernel modules is saved and remains accessible via
@@ -1347,7 +1544,7 @@
hardlockup_all_cpu_backtrace=
[KNL] Should the hard-lockup detector generate
backtraces on all cpus.
- Format: <integer>
+ Format: 0 | 1
hashdist= [KNL,NUMA] Large hashes allocated during boot
are distributed across NUMA nodes. Defaults on
@@ -1373,9 +1570,6 @@
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
@@ -1389,19 +1583,38 @@
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).
+ hugetlb_cma= [HW] The size of a cma area used for allocation
+ of gigantic hugepages.
+ Format: nn[KMGTPE]
+
+ Reserve a cma area of given size and allocate gigantic
+ hugepages using the cma allocator. If enabled, the
+ boot-time allocation of gigantic hugepages is skipped.
+
+ hugepages= [HW] Number of HugeTLB pages to allocate at boot.
+ If this follows hugepagesz (below), it specifies
+ the number of pages of hugepagesz to be allocated.
+ If this is the first HugeTLB parameter on the command
+ line, it specifies the number of pages to allocate for
+ the default huge page size. See also
+ Documentation/admin-guide/mm/hugetlbpage.rst.
+ Format: <integer>
+
+ hugepagesz=
+ [HW] The size of the HugeTLB pages. This is used in
+ conjunction with hugepages (above) to allocate huge
+ pages of a specific size at boot. The pair
+ hugepagesz=X hugepages=Y can be specified once for
+ each supported huge page size. Huge page sizes are
+ architecture dependent. See also
+ Documentation/admin-guide/mm/hugetlbpage.rst.
+ Format: size[KMG]
hung_task_panic=
[KNL] Should the hung task detector generate panics.
- Format: <integer>
+ Format: 0 | 1
- A nonzero value instructs the kernel to panic when a
+ A value of 1 instructs the kernel to panic when a
hung task is detected. The default value is controlled
by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
option. The value selected by this boot parameter can
@@ -1412,6 +1625,15 @@
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.
+
+ hvc_dcc.enable= [ARM,ARM64] Enable DCC driver at runtime. For GKI,
+ disabled at runtime by default to prevent
+ crashes in devices which do not support DCC.
+
+ hv_nopvspin [X86,HYPER_V] Disables the paravirt spinlock optimizations
+ which allow the hypervisor to 'idle' the
+ guest on lock contention.
+
keep_bootcon [KNL]
Do not unregister boot console at start. This is only
useful for debugging when something happens in the window
@@ -1489,7 +1711,7 @@
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.
+ See Documentation/ide/ide.rst.
ide-generic.probe-mask= [HW] (E)IDE subsystem
Format: <int>
@@ -1570,7 +1792,7 @@
Format: { "off" | "enforce" | "fix" | "log" }
default: "enforce"
- ima_appraise_tcb [IMA]
+ ima_appraise_tcb [IMA] Deprecated. Use ima_policy= instead.
The builtin appraise policy appraises all files
owned by uid=0.
@@ -1597,8 +1819,7 @@
uid=0.
The "appraise_tcb" policy appraises the integrity of
- all files owned by root. (This is the equivalent
- of ima_appraise_tcb.)
+ all files owned by root.
The "secure_boot" policy appraises the integrity
of files (eg. kexec kernel image, kernel modules,
@@ -1656,6 +1877,13 @@
initrd= [BOOT] Specify the location of the initial ramdisk
+ initrdmem= [KNL] Specify a physical address and size from which to
+ load the initrd. If an initrd is compiled in or
+ specified in the bootparams, it takes priority over this
+ setting.
+ Format: ss[KMG],nn[KMG]
+ Default is 0, 0
+
init_on_alloc= [MM] Fill newly allocated pages and heap objects with
zeroes.
Format: 0 | 1
@@ -1665,7 +1893,7 @@
Format: 0 | 1
Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON.
- init_pkru= [x86] Specify the default memory protection keys rights
+ 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.
@@ -1673,7 +1901,7 @@
inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
Format: <irq>
- int_pln_enable [x86] Enable power limit notification interrupt
+ int_pln_enable [X86] Enable power limit notification interrupt
integrity_audit=[IMA]
Format: { "0" | "1" }
@@ -1691,7 +1919,7 @@
bypassed by not enabling DMAR with this option. In
this case, gfx device will use physical address for
DMA.
- forcedac [x86_64]
+ 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
@@ -1706,12 +1934,11 @@
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.
+ sm_on [Default Off]
+ By default, scalable mode will be disabled even if the
+ hardware advertises that it has support for the scalable
+ mode translation. With this option set, scalable mode
+ will be used on hardware which claims to support it.
tboot_noforce [Default Off]
Do not force the Intel IOMMU enabled under tboot.
By default, tboot will force Intel IOMMU on, which
@@ -1721,6 +1948,11 @@
Note that using this option lowers the security
provided by tboot because it makes the system
vulnerable to DMA attacks.
+ nobounce [Default off]
+ Disable bounce buffer for untrusted devices such as
+ the Thunderbolt devices. This will treat the untrusted
+ devices as the trusted ones, hence might expose security
+ risks of DMA attacks.
intel_idle.max_cstate= [KNL,HW,ACPI,X86]
0 disables intel_idle and fall back on acpi_idle.
@@ -1772,7 +2004,7 @@
strict regions from userspace.
relaxed
- iommu= [x86]
+ iommu= [X86]
off
force
noforce
@@ -1782,19 +2014,31 @@
merge
nomerge
soft
- pt [x86]
- nopt [x86]
+ pt [X86]
+ nopt [X86]
nobypass [PPC/POWERNV]
Disable IOMMU bypass, using IOMMU for PCI devices.
+ iommu.strict= [ARM64] Configure TLB invalidation behaviour
+ Format: { "0" | "1" }
+ 0 - Lazy mode.
+ Request that DMA unmap operations use deferred
+ invalidation of hardware TLBs, for increased
+ throughput at the cost of reduced device isolation.
+ Will fall back to strict mode if not supported by
+ the relevant IOMMU driver.
+ 1 - Strict mode (default).
+ DMA unmap operations invalidate IOMMU hardware TLBs
+ synchronously.
+
iommu.passthrough=
- [ARM64] Configure DMA to bypass the IOMMU by default.
+ [ARM64, X86] Configure DMA to bypass the IOMMU by default.
Format: { "0" | "1" }
0 - Use IOMMU translation for DMA.
1 - Bypass the IOMMU for DMA.
- unset - Use IOMMU translation for DMA.
+ unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
- io7= [HW] IO7 for Marvel based alpha systems
+ io7= [HW] IO7 for Marvel-based Alpha systems
See comment before marvel_specify_io7 in
arch/alpha/kernel/core_marvel.c.
@@ -1809,7 +2053,10 @@
No delay
ip= [IP_PNP]
- See Documentation/filesystems/nfs/nfsroot.txt.
+ See Documentation/admin-guide/nfs/nfsroot.rst.
+
+ ipcmni_extend [KNL] Extend the maximum number of unique System V
+ IPC identifiers from 32,768 to 16,777,216.
irqaffinity= [SMP] Set the default irq affinity mask
The argument is a cpu list, as described above.
@@ -1828,6 +2075,11 @@
that use the kernel as a bootloader, and thus want
to let secondary kernels in charge of setting up
LPIs.
+
+ irqchip.gicv3_pseudo_nmi= [ARM64]
+ Enables support for pseudo-NMIs in the kernel. This
+ requires the kernel to be built with
+ CONFIG_ARM64_PSEUDO_NMI.
irqfixup [HW]
When an interrupt is not handled search all handlers
@@ -1878,32 +2130,87 @@
<cpu number> begins at 0 and the maximum value is
"number of CPUs in system - 1".
+ managed_irq
+
+ Isolate from being targeted by managed interrupts
+ which have an interrupt mask containing isolated
+ CPUs. The affinity of managed interrupts is
+ handled by the kernel and cannot be changed via
+ the /proc/irq/* interfaces.
+
+ This isolation is best effort and only effective
+ if the automatically assigned interrupt mask of a
+ device queue contains isolated and housekeeping
+ CPUs. If housekeeping CPUs are online then such
+ interrupts are directed to the housekeeping CPU
+ so that IO submitted on the housekeeping CPU
+ cannot disturb the isolated CPU.
+
+ If a queue's affinity mask contains only isolated
+ CPUs then this parameter has no effect on the
+ interrupt routing decision, though interrupts are
+ only delivered when tasks running on those
+ isolated CPUs submit IO. IO submitted on
+ housekeeping CPUs has no influence on those
+ queues.
+
The format of <cpu-list> is described above.
-
-
iucv= [HW,NET]
- ivrs_ioapic [HW,X86_64]
+ 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:
+ mapping provided in the IVRS ACPI table.
+ By default, PCI segment is 0, and can be omitted.
+
+ For example, to map IOAPIC-ID decimal 10 to
+ PCI segment 0x1 and PCI device 00:14.0,
+ write the parameter as:
+ ivrs_ioapic=10@0001:00:14.0
+
+ Deprecated formats:
+ * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
+ write the parameter as:
ivrs_ioapic[10]=00:14.0
+ * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
+ PCI device 00:14.0 write the parameter as:
+ ivrs_ioapic[10]=0001:00:14.0
- ivrs_hpet [HW,X86_64]
+ 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
+ mapping provided in the IVRS ACPI table.
+ By default, PCI segment is 0, and can be omitted.
- ivrs_acpihid [HW,X86_64]
+ For example, to map HPET-ID decimal 10 to
+ PCI segment 0x1 and PCI device 00:14.0,
+ write the parameter as:
+ ivrs_hpet=10@0001:00:14.0
+
+ Deprecated formats:
+ * To map HPET-ID decimal 0 to PCI device 00:14.0
+ write the parameter as:
+ ivrs_hpet[0]=00:14.0
+ * To map HPET-ID decimal 10 to PCI segment 0x1 and
+ PCI device 00:14.0 write the parameter as:
+ ivrs_ioapic[10]=0001:00:14.0
+
+ 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:
+ mapping provided in the IVRS ACPI table.
+ By default, PCI segment is 0, and can be omitted.
+
+ For example, to map UART-HID:UID AMD0020:0 to
+ PCI segment 0x1 and PCI device ID 00:14.5,
+ write the parameter as:
+ ivrs_acpihid=AMD0020:0@0001:00:14.5
+
+ Deprecated formats:
+ * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
+ PCI device ID 00:14.5, write the parameter as:
ivrs_acpihid[00:14.5]=AMD0020:0
+ * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
+ PCI device ID 00:14.5, write the parameter as:
+ ivrs_acpihid[0001:00:14.5]=AMD0020:0
js= [HW,JOY] Analog joystick
See Documentation/input/joydev/joystick.rst.
@@ -1967,10 +2274,25 @@
kms, kbd format: kms,kbd
kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
+ kgdboc_earlycon= [KGDB,HW]
+ If the boot console provides the ability to read
+ characters and can work in polling mode, you can use
+ this parameter to tell kgdb to use it as a backend
+ until the normal console is registered. Intended to
+ be used together with the kgdboc parameter which
+ specifies the normal console to transition to.
+
+ The name of the early console should be specified
+ as the value of this parameter. Note that the name of
+ the early console might be different than the tty
+ name passed to kgdboc. It's OK to leave the value
+ blank and the first boot console that implements
+ read() will be picked.
+
kgdbwait [KGDB] Stop kernel execution and enter the
kernel debugger at the earliest opportunity.
- kmac= [MIPS] korina ethernet MAC address.
+ kmac= [MIPS] Korina ethernet MAC address.
Configure the RouterBoard 532 series on-chip
Ethernet adapter MAC address.
@@ -1979,6 +2301,19 @@
Default: on
Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
the default is off.
+
+ kprobe_event=[probe-list]
+ [FTRACE] Add kprobe events and enable at boot time.
+ The probe-list is a semicolon delimited list of probe
+ definitions. Each definition is same as kprobe_events
+ interface, but the parameters are comma delimited.
+ For example, to add a kprobe event on vfs_read with
+ arg1 and arg2, add to the command line;
+
+ kprobe_event=p,vfs_read,$arg1,$arg2
+
+ See also Documentation/trace/kprobetrace.rst "Kernel
+ Boot Parameter" section.
kpti= [ARM64] Control page table isolation of user
and kernel address spaces.
@@ -2022,6 +2357,21 @@
for all guests.
Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
+ kvm-arm.mode=
+ [KVM,ARM] Select one of KVM/arm64's modes of operation.
+
+ none: Forcefully disable KVM.
+
+ nvhe: Standard nVHE-based mode, without support for
+ protected guests.
+
+ protected: nVHE-based mode with support for guests whose
+ state is kept private from the host.
+ Not valid if the kernel is running in EL2.
+
+ Defaults to VHE/nVHE based on hardware support and
+ the value of CONFIG_ARM64_VHE.
+
kvm-arm.vgic_v3_group0_trap=
[KVM,ARM] Trap guest accesses to GICv3 group-0
system registers
@@ -2037,6 +2387,14 @@
kvm-arm.vgic_v4_enable=
[KVM,ARM] Allow use of GICv4 for direct injection of
LPIs.
+
+ kvm_cma_resv_ratio=n [PPC]
+ Reserves given percentage from system memory area for
+ contiguous memory allocation for KVM hash pagetable
+ allocation.
+ By default it reserves 5% of total system memory.
+ Format: <integer>
+ Default: 5
kvm-intel.ept= [KVM,Intel] Disable extended page tables
(virtualized MMU) support on capable Intel chips.
@@ -2151,9 +2509,10 @@
lapic [X86-32,APIC] Enable the local APIC even if BIOS
disabled it.
- lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline
+ lapic= [X86,APIC] Do not use TSC deadline
value for LAPIC timer one-shot implementation. Default
back to the programmable timer unit in the LAPIC.
+ Format: notscdeadline
lapic_timer_c2_ok [X86,APIC] trust the local apic timer
in C2 power state.
@@ -2225,8 +2584,13 @@
memblock=debug [KNL] Enable memblock debug messages.
- load_ramdisk= [RAM] List of ramdisks to load from floppy
- See Documentation/blockdev/ramdisk.txt.
+ android12_only.will_be_removed_soon.memblock_nomap_remove= [KNL]
+ Setting this to true through kernel command line will
+ call memblock_remove on the regions marked with no-map
+ property thereby saving memory by removing page structs
+ for those regions. By default this is set to false.
+
+ load_ramdisk= [RAM] [Deprecated]
lockd.nlm_grace_period=P [NFS] Assign grace period.
Format: <integer>
@@ -2239,6 +2603,15 @@
lockd.nlm_udpport=M [NFS] Assign UDP port.
Format: <integer>
+
+ lockdown= [SECURITY]
+ { integrity | confidentiality }
+ Enable the kernel lockdown feature. If set to
+ integrity, kernel features that allow userland to
+ modify the running kernel are disabled. If set to
+ confidentiality, kernel features that allow userland
+ to extract confidential information from the kernel
+ are also disabled.
locktorture.nreaders_stress= [KNL]
Set the number of locking read-acquisition kthreads.
@@ -2344,12 +2717,18 @@
ltpc= [NET]
Format: <io>,<irq>,<dma>
+ lsm.debug [SECURITY] Enable LSM initialization debugging output.
+
+ lsm=lsm1,...,lsmN
+ [SECURITY] Choose order of LSM initialization. This
+ overrides CONFIG_LSM, and the "security=" parameter.
+
machvec= [IA-64] Force the use of a particular machine-vector
(machvec) in a generic kernel.
- Example: machvec=hpzx1_swiotlb
+ Example: machvec=hpzx1
- machtype= [Loongson] Share the same kernel image file between different
- yeeloong laptop.
+ machtype= [Loongson] Share the same kernel image file between
+ different yeeloong laptops.
Example: machtype=lemote-yeeloong-2f-7inch
max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
@@ -2373,7 +2752,7 @@
mce [X86-32] Machine Check Exception
- mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
+ mce=option [X86-64] See Documentation/x86/x86_64/boot-options.rst
md= [HW] RAID subsystems devices and level
See Documentation/admin-guide/md.rst.
@@ -2415,12 +2794,21 @@
For details see: Documentation/admin-guide/hw-vuln/mds.rst
mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
- Amount of memory to be used when the kernel is not able
- to see the whole system memory or for test.
+ Amount of memory to be used in cases as follows:
+
+ 1 for test;
+ 2 when the kernel is not able to see the whole system memory;
+ 3 memory that lies after 'mem=' boundary is excluded from
+ the hypervisor, then assigned to KVM guests.
+
[X86] Work as limiting max address. Use together
with memmap= to avoid physical address space collisions.
Without memmap= PCI devices could be placed at addresses
belonging to unused RAM.
+
+ Note that this only takes effects during boot time since
+ in above case 3, memory may need be hot added after boot
+ if system memory of hypervisor is not sufficient.
mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
memory.
@@ -2435,7 +2823,7 @@
set according to the
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
option.
- See Documentation/memory-hotplug.txt.
+ See Documentation/admin-guide/mm/memory-hotplug.rst.
memmap=exactmap [KNL,X86] Enable setting of an exact
E820 memory map, as specified by the user.
@@ -2506,7 +2894,7 @@
seconds. Use this parameter to check at some
other rate. 0 disables periodic checking.
- memtest= [KNL,X86,ARM] Enable memtest
+ memtest= [KNL,X86,ARM,PPC] Enable memtest
Format: <integer>
default : 0 <disable>
Specifies the number of memtest passes to be
@@ -2524,7 +2912,7 @@
mem_encrypt=on: Activate SME
mem_encrypt=off: Do not activate SME
- Refer to Documentation/x86/amd-memory-encryption.txt
+ Refer to Documentation/virt/kvm/amd-memory-encryption.rst
for details on when memory encryption can be activated.
mem_sleep_default= [SUSPEND] Default system suspend mode:
@@ -2534,7 +2922,7 @@
See Documentation/admin-guide/pm/sleep-states.rst.
meye.*= [HW] Set MotionEye Camera parameters
- See Documentation/media/v4l-drivers/meye.rst.
+ See Documentation/admin-guide/media/meye.rst.
mfgpt_irq= [IA-32] Specify the IRQ to use for the
Multi-Function General Purpose Timers on AMD Geode
@@ -2569,7 +2957,7 @@
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
+ https://repo.or.cz/w/linux-2.6/mini2440.git
mitigations=
[X86,PPC,S390,ARM64] Control optional mitigations for
@@ -2581,21 +2969,23 @@
Disable all optional CPU mitigations. This
improves system performance, but it may also
expose users to several CPU vulnerabilities.
- Equivalent to: nopti [X86,PPC]
+ Equivalent to: gather_data_sampling=off [X86]
kpti=0 [ARM64]
- nospectre_v1 [PPC]
- nobp=0 [S390]
- nospectre_v1 [X86]
- nospectre_v2 [X86,PPC,S390,ARM64]
- spectre_v2_user=off [X86]
- spec_store_bypass_disable=off [X86,PPC]
- ssbd=force-off [ARM64]
+ kvm.nx_huge_pages=off [X86]
l1tf=off [X86]
mds=off [X86]
- tsx_async_abort=off [X86]
- kvm.nx_huge_pages=off [X86]
+ mmio_stale_data=off [X86]
no_entry_flush [PPC]
no_uaccess_flush [PPC]
+ nobp=0 [S390]
+ nopti [X86,PPC]
+ nospectre_v1 [X86,PPC]
+ nospectre_v2 [X86,PPC,S390,ARM64]
+ retbleed=off [X86]
+ spec_store_bypass_disable=off [X86,PPC]
+ spectre_v2_user=off [X86]
+ ssbd=force-off [ARM64]
+ tsx_async_abort=off [X86]
Exceptions:
This does not have any effect on
@@ -2617,6 +3007,8 @@
Equivalent to: l1tf=flush,nosmt [X86]
mds=full,nosmt [X86]
tsx_async_abort=full,nosmt [X86]
+ mmio_stale_data=full,nosmt [X86]
+ retbleed=auto,nosmt [X86]
mminit_loglevel=
[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
@@ -2625,6 +3017,40 @@
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.
+
+ mmio_stale_data=
+ [X86,INTEL] Control mitigation for the Processor
+ MMIO Stale Data vulnerabilities.
+
+ Processor MMIO Stale Data is a class of
+ vulnerabilities that may expose data after an MMIO
+ operation. Exposed data could originate or end in
+ the same CPU buffers as affected by MDS and TAA.
+ Therefore, similar to MDS and TAA, the mitigation
+ is to clear the affected CPU buffers.
+
+ This parameter controls the mitigation. The
+ options are:
+
+ full - Enable mitigation on vulnerable CPUs
+
+ full,nosmt - Enable mitigation and disable SMT on
+ vulnerable CPUs.
+
+ off - Unconditionally disable mitigation
+
+ On MDS or TAA affected machines,
+ mmio_stale_data=off can be prevented by an active
+ MDS or TAA mitigation as these vulnerabilities are
+ mitigated with the same mechanism so in order to
+ disable this mitigation, you need to specify
+ mds=off and tsx_async_abort=off too.
+
+ Not specifying this option is equivalent to
+ mmio_stale_data=full.
+
+ For details see:
+ Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
module.sig_enforce
[KNL] When CONFIG_MODULE_SIG is set, this means that
@@ -2670,11 +3096,31 @@
<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
mtdparts= [MTD]
- See drivers/mtd/cmdlinepart.c.
+ 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.
+
+ kswapd_per_node=
+ kswapd_per_node allows you to control the number of kswapd threads
+ running on the system. This provides the ability to devote additional
+ CPU resources toward proactive page replacement with the goal of
+ reducing direct reclaims. When direct reclaims are prevented, the CPU
+ consumed by them is prevented as well. Depending on the workload, the
+ result can cause aggregate CPU usage on the system to go up, down or
+ stay the same.
+
+ More aggressive page replacement can reduce direct reclaims which
+ cause latency for tasks and decrease throughput when doing filesystem
+ IO through the pagecache. Direct reclaims are recorded using the
+ allocstall counter in /proc/vmstat.
+
+ The range of acceptible values are 1-16. Always start with lower
+ values in the 2-6 range. Higher values should be justified with
+ testing. If direct reclaims occur in spite of high values, the cost
+ of direct reclaims (in latency) that occur can be higher due to
+ increased lock contention.
onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
@@ -2728,13 +3174,13 @@
Default value is 0.
nfsaddrs= [NFS] Deprecated. Use ip= instead.
- See Documentation/filesystems/nfs/nfsroot.txt.
+ See Documentation/admin-guide/nfs/nfsroot.rst.
nfsroot= [NFS] nfs root filesystem for disk-less boxes.
- See Documentation/filesystems/nfs/nfsroot.txt.
+ See Documentation/admin-guide/nfs/nfsroot.rst.
nfsrootdebug [NFS] enable nfsroot debugging messages.
- See Documentation/filesystems/nfs/nfsroot.txt.
+ See Documentation/admin-guide/nfs/nfsroot.rst.
nfs.callback_nr_threads=
[NFSv4] set the total number of threads that the
@@ -2833,6 +3279,10 @@
and gids from such clients. This is intended to ease
migration from NFSv2/v3.
+ nmi_backtrace.backtrace_idle [KNL]
+ Dump stacks even of idle CPUs in response to an
+ NMI stack-backtrace request.
+
nmi_debug= [KNL,SH] Specify one or more actions to take
when a NMI is triggered.
Format: [state][,regs][,debounce][,die]
@@ -2843,8 +3293,9 @@
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,
+ timeout occurs (or 'nopanic' to not panic on an NMI
+ watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set)
+ To disable both hard and soft lockup detectors,
please see 'nowatchdog'.
This is useful when you use a panic=... timeout and
need the box quickly up again.
@@ -2864,6 +3315,8 @@
no5lvl [X86-64] Disable 5-level paging mode. Forces
kernel to use 4-level paging instead.
+ nofsgsbase [X86] Disables FSGSBASE instructions.
+
no_console_suspend
[HW] Never suspend the console
Disable suspending of consoles during suspend and
@@ -2878,6 +3331,17 @@
it. Users could use console_suspend (usually
/sys/module/printk/parameters/console_suspend) to
turn on/off it dynamically.
+
+ novmcoredd [KNL,KDUMP]
+ Disable device dump. Device dump allows drivers to
+ append dump data to vmcore so you can collect driver
+ specified debug info. Drivers can append the data
+ without any limit and this data is stored in memory,
+ so this may cause significant memory stress. Disabling
+ device dump can help save memory but the driver debug
+ data will be no longer available. This parameter
+ is only available when CONFIG_PROC_VMCORE_DEVICE_DUMP
+ is set.
noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
caches in the slab allocator. Saves per-node memory,
@@ -2915,11 +3379,11 @@
noexec=on: enable non-executable mappings (default)
noexec=off: disable non-executable mappings
- nosmap [X86]
+ nosmap [X86,PPC]
Disable SMAP (Supervisor Mode Access Prevention)
even if it is supported by processor.
- nosmep [X86]
+ nosmep [X86,PPC]
Disable SMEP (Supervisor Mode Execution Prevention)
even if it is supported by processor.
@@ -2936,18 +3400,18 @@
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.
+ nohugeiomap [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.
nosmt [KNL,S390] Disable symmetric multithreading (SMT).
Equivalent to smt=1.
- [KNL,x86] Disable symmetric multithreading (SMT).
+ [KNL,X86] Disable symmetric multithreading (SMT).
nosmt=force: Force disable SMT, cannot be undone
via the sysfs control file.
- nospectre_v1 [X66, PPC] Disable mitigations for Spectre Variant 1
- (bounds check bypass). With this option data leaks
- are possible in the system.
+ nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1
+ (bounds check bypass). With this option data leaks are
+ possible in the system.
nospectre_v2 [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for
the Spectre variant 2 (indirect branch prediction)
@@ -2993,6 +3457,20 @@
interrupt wake-up latency, which may improve performance
in certain environments such as networked servers or
real-time systems.
+
+ no_hash_pointers
+ Force pointers printed to the console or buffers to be
+ unhashed. By default, when a pointer is printed via %p
+ format string, that pointer is "hashed", i.e. obscured
+ by hashing the pointer value. This is a security feature
+ that hides actual kernel addresses from unprivileged
+ users, but it also makes debugging the kernel more
+ difficult since unequal pointers can no longer be
+ compared. However, if this command-line option is
+ specified, then all normal pointers will have their true
+ value printed. This option should only be specified when
+ debugging the kernel. Please do not use on production
+ kernels.
nohibernate [HIBERNATION] Disable hibernation and resume.
@@ -3042,9 +3520,9 @@
[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
+ no-steal-acc [X86,PV_OPS,ARM64] Disable paravirtualized steal time
+ accounting. steal time is computed, but won't
+ influence scheduler behaviour
nolapic [X86-32,APIC] Do not enable or use the local APIC.
@@ -3151,16 +3629,10 @@
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.
-
- of_devlink [OF, KNL] Create device links between consumer and
- supplier devices by scanning the devictree to infer the
- consumer/supplier relationships. A consumer device
- will not be probed until all the supplier devices have
- probed successfully.
+ See Documentation/admin-guide/sysctl/vm.rst for details.
ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
- See Documentation/debugging-via-ohci1394.txt for more
+ See Documentation/core-api/debugging-via-ohci1394.rst for more
info.
olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
@@ -3195,6 +3667,16 @@
This will also cause panics on machine check exceptions.
Useful together with panic=30 to trigger a reboot.
+ page_alloc.shuffle=
+ [KNL] Boolean flag to control whether the page allocator
+ should randomize its free lists. The randomization may
+ be automatically enabled if the kernel detects it is
+ running on a platform with a direct-mapped memory-side
+ cache, and this parameter can be used to
+ override/disable that behavior. The state of the flag
+ can be read from sysfs at:
+ /sys/module/page_alloc/parameters/shuffle.
+
page_owner= [KNL] Boot-time page_owner enabling option.
Storage of the information about who allocated
each page is disabled in default. With this switch,
@@ -3213,8 +3695,36 @@
timeout < 0: reboot immediately
Format: <timeout>
+ panic_print= Bitmask for printing system info when panic happens.
+ User can chose combination of the following bits:
+ bit 0: print all tasks info
+ bit 1: print system memory info
+ bit 2: print timer info
+ bit 3: print locks info if CONFIG_LOCKDEP is on
+ bit 4: print ftrace buffer
+ bit 5: print all printk messages in buffer
+
+ panic_on_taint= Bitmask for conditionally calling panic() in add_taint()
+ Format: <hex>[,nousertaint]
+ Hexadecimal bitmask representing the set of TAINT flags
+ that will cause the kernel to panic when add_taint() is
+ called with any of the flags in this set.
+ The optional switch "nousertaint" can be utilized to
+ prevent userspace forced crashes by writing to sysctl
+ /proc/sys/kernel/tainted any flagset matching with the
+ bitmask set on panic_on_taint.
+ See Documentation/admin-guide/tainted-kernels.rst for
+ extra details on the taint flags that users can pick
+ to compose the bitmask to assign to panic_on_taint.
+
panic_on_warn panic() instead of WARN(). Useful to cause kdump
on a WARN().
+
+ pelt= [KNL] Boot-time parameter changing the PELT half life in ms
+ Format: <int>
+ 32: Set the half life to 32ms
+ 8: Set the half life to 8ms
+ default: 32
crash_kexec_post_notifiers
Run kdump after running panic-notifiers and dumping
@@ -3262,7 +3772,7 @@
pcd. [PARIDE]
See header of drivers/block/paride/pcd.c.
- See also Documentation/blockdev/paride.txt.
+ See also Documentation/admin-guide/blockdev/paride.rst.
pci=option[,option...] [PCI] various PCI subsystem options.
@@ -3422,12 +3932,13 @@
specify the device is described above.
If <order of align> is not specified,
PAGE_SIZE is used as alignment.
- PCI-PCI bridge can be specified, if resource
+ A PCI-PCI bridge can be specified if resource
windows need to be expanded.
To specify the alignment for several
instances of a device, the PCI vendor,
device, subvendor, and subdevice may be
- specified, e.g., 4096@pci:8086:9c22:103c:198f
+ specified, e.g., 12@pci:8086:9c22:103c:198f
+ for 4096-byte alignment.
ecrc= Enable/disable PCIe ECRC (transaction layer
end-to-end CRC checking).
bios: Use BIOS/firmware settings. This is the
@@ -3437,8 +3948,15 @@
hpiosize=nn[KMG] The fixed amount of bus space which is
reserved for hotplug bridge's IO window.
Default size is 256 bytes.
+ hpmmiosize=nn[KMG] The fixed amount of bus space which is
+ reserved for hotplug bridge's MMIO window.
+ Default size is 2 megabytes.
+ hpmmioprefsize=nn[KMG] The fixed amount of bus space which is
+ reserved for hotplug bridge's MMIO_PREF window.
+ Default size is 2 megabytes.
hpmemsize=nn[KMG] The fixed amount of bus space which is
- reserved for hotplug bridge's memory window.
+ reserved for hotplug bridge's MMIO and
+ MMIO_PREF window.
Default size is 2 megabytes.
hpbussize=nn The minimum amount of additional bus numbers
reserved for buses below a hotplug bridge.
@@ -3471,6 +3989,10 @@
bridges without forcing it upstream. Note:
this removes isolation between devices and
may put more devices in an IOMMU group.
+ force_floating [S390] Force usage of floating interrupts.
+ nomio [S390] Do not use MIO instructions.
+ norid [S390] ignore the RID field and force use of
+ one PCI domain per PCI function
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
@@ -3483,6 +4005,8 @@
even if the platform doesn't give the OS permission to
use them. This may cause conflicts if the platform
also tries to use these services.
+ dpc-native Use native PCIe service for DPC only. May
+ cause conflicts if firmware uses AER or DPC.
compat Disable native PCIe services (PME, AER, DPC, PCIe
hotplug).
@@ -3504,7 +4028,7 @@
needed on a platform with proper driver support.
pd. [PARIDE]
- See Documentation/blockdev/paride.txt.
+ See Documentation/admin-guide/blockdev/paride.rst.
pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
boot time.
@@ -3519,13 +4043,13 @@
and performance comparison.
pf. [PARIDE]
- See Documentation/blockdev/paride.txt.
+ See Documentation/admin-guide/blockdev/paride.rst.
pg. [PARIDE]
- See Documentation/blockdev/paride.txt.
+ See Documentation/admin-guide/blockdev/paride.rst.
pirq= [SMP,APIC] Manual mp-table setup
- See Documentation/x86/i386/IO-APIC.txt.
+ See Documentation/x86/i386/IO-APIC.rst.
plip= [PPT,NET] Parallel port network link
Format: { parport<nr> | timid | 0 }
@@ -3534,6 +4058,9 @@
pmtmr= [X86] Manual setup of pmtmr I/O Port.
Override pmtimer IOPort with a hex value.
e.g. pmtmr=0x508
+
+ pm_debug_messages [SUSPEND,KNL]
+ Enable suspend/resume debug messages during boot up.
pnp.debug=1 [PNP]
Enable PNP debug messages (depends on the
@@ -3632,9 +4159,12 @@
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.
+ prompt_ramdisk= [RAM] [Deprecated]
+
+ prot_virt= [S390] enable hosting protected virtual machines
+ isolated from the hypervisor (if hardware supports
+ that).
+ Format: <bool>
psi= [KNL] Enable or disable pressure stall information
tracking.
@@ -3656,9 +4186,9 @@
pstore.backend= Specify the name of the pstore backend to use
pt. [PARIDE]
- See Documentation/blockdev/paride.txt.
+ See Documentation/admin-guide/blockdev/paride.rst.
- pti= [X86_64] Control Page Table Isolation of user and
+ 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.
@@ -3670,7 +4200,7 @@
Not specifying this option is equivalent to pti=auto.
- nopti [X86_64]
+ nopti [X86-64]
Equivalent to pti=off
pty.legacy_count=
@@ -3685,13 +4215,21 @@
See Documentation/admin-guide/md.rst.
ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
- See Documentation/blockdev/ramdisk.txt.
+ See Documentation/admin-guide/blockdev/ramdisk.rst.
+
+ ramdisk_start= [RAM] RAM disk image start address
random.trust_cpu={on,off}
[KNL] Enable or disable trusting the use of the
CPU's random number generator (if available) to
fully seed the kernel's CRNG. Default is controlled
by CONFIG_RANDOM_TRUST_CPU.
+
+ random.trust_bootloader={on,off}
+ [KNL] Enable or disable trusting the use of a
+ seed passed by the bootloader (if available) to
+ fully seed the kernel's CRNG. Default is controlled
+ by CONFIG_RANDOM_TRUST_BOOTLOADER.
ras=option[,option,...] [KNL] RAS-specific options
@@ -3700,18 +4238,20 @@
see CONFIG_RAS_CEC help text.
rcu_nocbs= [KNL]
- The argument is a cpu list, as described above.
+ The argument is a cpu list, as described above,
+ except that the string "all" can be used to
+ specify every CPU on the system.
In kernels built with CONFIG_RCU_NOCB_CPU=y, set
the specified list of CPUs to be no-callback CPUs.
- Invocation of these CPUs' RCU callbacks will
- be offloaded to "rcuox/N" kthreads created for
- that purpose, where "x" is "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.
+ Invocation of these CPUs' RCU callbacks will be
+ offloaded to "rcuox/N" kthreads created for that
+ purpose, where "x" is "p" for RCU-preempt, and
+ "s" for RCU-sched, and "N" is the CPU number.
+ This reduces OS jitter on the offloaded CPUs,
+ which can be useful for HPC and real-time
+ workloads. It can also improve energy efficiency
+ for asymmetric multiprocessors.
rcu_nocb_poll [KNL]
Rather than requiring that offloaded CPUs
@@ -3747,6 +4287,12 @@
the propagation of recent CPU-hotplug changes up
the rcu_node combining tree.
+ rcutree.use_softirq= [KNL]
+ If set to zero, move all RCU_SOFTIRQ processing to
+ per-CPU rcuc kthreads. Defaults to a non-zero
+ value, meaning that RCU_SOFTIRQ is used by default.
+ Specify rcutree.use_softirq=0 to use rcuc kthreads.
+
rcutree.rcu_fanout_exact= [KNL]
Disable autobalancing of the rcu_node combining
tree. This is used by rcutorture, and might
@@ -3761,11 +4307,13 @@
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.rcu_min_cached_objs= [KNL]
+ Minimum number of objects which are cached and
+ maintained per one CPU. Object size is equal
+ to PAGE_SIZE. The cache allows to reduce the
+ pressure to page allocator, also it makes the
+ whole algorithm to behave better in low memory
+ condition.
rcutree.jiffies_till_first_fqs= [KNL]
Set delay from grace-period initialization to
@@ -3778,6 +4326,20 @@
quiescent states. Units are jiffies, minimum
value is one, and maximum value is HZ.
+ rcutree.jiffies_till_sched_qs= [KNL]
+ Set required age in jiffies for a
+ given grace period before RCU starts
+ soliciting quiescent-state help from
+ rcu_note_context_switch() and cond_resched().
+ If not specified, the kernel will calculate
+ a value based on the most recent settings
+ of rcutree.jiffies_till_first_fqs
+ and rcutree.jiffies_till_next_fqs.
+ This calculated value may be viewed in
+ rcutree.jiffies_to_sched_qs. Any attempt to set
+ rcutree.jiffies_to_sched_qs will be cheerfully
+ overwritten.
+
rcutree.kthread_prio= [KNL,BOOT]
Set the SCHED_FIFO priority of the RCU per-CPU
kthreads (rcuc/N). This value is also used for
@@ -3789,12 +4351,13 @@
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.rcu_nocb_gp_stride= [KNL]
+ Set the number of NOCB callback kthreads in
+ each group, which defaults to the square root
+ of the number of CPUs. Larger numbers reduce
+ the wakeup overhead on the global grace-period
+ kthread, but increases that same overhead on
+ each group's NOCB grace-period kthread.
rcutree.qhimark= [KNL]
Set threshold of queued RCU callbacks beyond which
@@ -3803,6 +4366,15 @@
rcutree.qlowmark= [KNL]
Set threshold of queued RCU callbacks below which
batch limiting is re-enabled.
+
+ rcutree.qovld= [KNL]
+ Set threshold of queued RCU callbacks beyond which
+ RCU's force-quiescent-state scan will aggressively
+ enlist help from cond_resched() and sched IPIs to
+ help CPUs more quickly reach quiescent states.
+ Set to less than zero to make this be set based
+ on rcutree.qhimark at boot time and to zero to
+ disable more aggressive help enlistment.
rcutree.rcu_idle_gp_delay= [KNL]
Set wakeup interval for idle CPUs that have
@@ -3821,28 +4393,55 @@
This wake_up() will be accompanied by a
WARN_ONCE() splat and an ftrace_dump().
- rcuperf.gp_async= [KNL]
+ rcutree.rcu_unlock_delay= [KNL]
+ In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels,
+ this specifies an rcu_read_unlock()-time delay
+ in microseconds. This defaults to zero.
+ Larger delays increase the probability of
+ catching RCU pointer leaks, that is, buggy use
+ of RCU-protected pointers after the relevant
+ rcu_read_unlock() has completed.
+
+ rcutree.sysrq_rcu= [KNL]
+ Commandeer a sysrq key to dump out Tree RCU's
+ rcu_node tree with an eye towards determining
+ why a new grace period has not yet started.
+
+ rcuscale.gp_async= [KNL]
Measure performance of asynchronous
grace-period primitives such as call_rcu().
- rcuperf.gp_async_max= [KNL]
+ rcuscale.gp_async_max= [KNL]
Specify the maximum number of outstanding
callbacks per writer thread. When a writer
thread exceeds this limit, it invokes the
corresponding flavor of rcu_barrier() to allow
previously posted callbacks to drain.
- rcuperf.gp_exp= [KNL]
+ rcuscale.gp_exp= [KNL]
Measure performance of expedited synchronous
grace-period primitives.
- rcuperf.holdoff= [KNL]
+ rcuscale.holdoff= [KNL]
Set test-start holdoff period. The purpose of
this parameter is to delay the start of the
test until boot completes in order to avoid
interference.
- rcuperf.nreaders= [KNL]
+ rcuscale.kfree_rcu_test= [KNL]
+ Set to measure performance of kfree_rcu() flooding.
+
+ rcuscale.kfree_nthreads= [KNL]
+ The number of threads running loops of kfree_rcu().
+
+ rcuscale.kfree_alloc_num= [KNL]
+ Number of allocations and frees done in an iteration.
+
+ rcuscale.kfree_loops= [KNL]
+ Number of loops doing rcuscale.kfree_alloc_num number
+ of allocations and frees.
+
+ rcuscale.nreaders= [KNL]
Set number of RCU readers. The value -1 selects
N, where N is the number of CPUs. A value
"n" less than -1 selects N-n+1, where N is again
@@ -3851,44 +4450,26 @@
A value of "n" less than or equal to -N selects
a single reader.
- rcuperf.nwriters= [KNL]
+ rcuscale.nwriters= [KNL]
Set number of RCU writers. The values operate
- the same as for rcuperf.nreaders.
+ the same as for rcuscale.nreaders.
N, where N is the number of CPUs
- rcuperf.perf_type= [KNL]
+ rcuscale.perf_type= [KNL]
Specify the RCU implementation to test.
- rcuperf.shutdown= [KNL]
+ rcuscale.shutdown= [KNL]
Shut the system down after performance tests
complete. This is useful for hands-off automated
testing.
- rcuperf.verbose= [KNL]
+ rcuscale.verbose= [KNL]
Enable additional printk() statements.
- rcuperf.writer_holdoff= [KNL]
+ rcuscale.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
@@ -3901,6 +4482,23 @@
rcutorture.fqs_stutter= [KNL]
Set wait time between force_quiescent_state bursts
in seconds.
+
+ rcutorture.fwd_progress= [KNL]
+ Enable RCU grace-period forward-progress testing
+ for the types of RCU supporting this notion.
+
+ rcutorture.fwd_progress_div= [KNL]
+ Specify the fraction of a CPU-stall-warning
+ period to do tight-loop forward-progress testing.
+
+ rcutorture.fwd_progress_holdoff= [KNL]
+ Number of seconds to wait between successive
+ forward-progress tests.
+
+ rcutorture.fwd_progress_need_resched= [KNL]
+ Enclose cond_resched() calls within checks for
+ need_resched() during tight-loop forward-progress
+ testing.
rcutorture.gp_cond= [KNL]
Use conditional/asynchronous update-side
@@ -3920,6 +4518,18 @@
rcutorture.gp_normal=, and rcutorture.gp_sync=
are zero, rcutorture acts as if is interpreted
they are all non-zero.
+
+ rcutorture.irqreader= [KNL]
+ Run RCU readers from irq handlers, or, more
+ accurately, from a timer handler. Not all RCU
+ flavors take kindly to this sort of thing.
+
+ rcutorture.leakpointer= [KNL]
+ Leak an RCU-protected pointer out of the reader.
+ This can of course result in splats, and is
+ intended to test the ability of things like
+ CONFIG_RCU_STRICT_GRACE_PERIOD=y to detect
+ such leaks.
rcutorture.n_barrier_cbs= [KNL]
Set callbacks/threads for rcu_barrier() testing.
@@ -3946,6 +4556,20 @@
Set time (jiffies) between CPU-hotplug operations,
or zero to disable CPU-hotplug testing.
+ rcutorture.read_exit= [KNL]
+ Set the number of read-then-exit kthreads used
+ to test the interaction of RCU updaters and
+ task-exit processing.
+
+ rcutorture.read_exit_burst= [KNL]
+ The number of times in a given read-then-exit
+ episode that a set of read-then-exit kthreads
+ is spawned.
+
+ rcutorture.read_exit_delay= [KNL]
+ The delay, in seconds, between successive
+ read-then-exit testing episodes.
+
rcutorture.shuffle_interval= [KNL]
Set task-shuffle interval (s). Shuffling tasks
allows some CPUs to go into dyntick-idle mode
@@ -3959,11 +4583,23 @@
Duration of CPU stall (s) to test RCU CPU stall
warnings, zero to disable.
+ rcutorture.stall_cpu_block= [KNL]
+ Sleep while stalling if set. This will result
+ in warnings from preemptible RCU in addition
+ to any other stall-related activity.
+
rcutorture.stall_cpu_holdoff= [KNL]
Time to wait (s) after boot before inducing stall.
rcutorture.stall_cpu_irqsoff= [KNL]
Disable interrupts while stalling if set.
+
+ rcutorture.stall_gp_kthread= [KNL]
+ Duration (s) of forced sleep within RCU
+ grace-period kthread to test RCU CPU stall
+ warnings, zero to disable. If both stall_cpu
+ and stall_gp_kthread are specified, the
+ kthread is starved first, then the CPU.
rcutorture.stat_interval= [KNL]
Time (s) between statistics printk()s.
@@ -3995,8 +4631,18 @@
rcutorture.verbose= [KNL]
Enable additional printk() statements.
+ rcupdate.rcu_cpu_stall_ftrace_dump= [KNL]
+ Dump ftrace buffer after reporting RCU CPU
+ stall warning.
+
rcupdate.rcu_cpu_stall_suppress= [KNL]
Suppress RCU CPU stall warning messages.
+
+ rcupdate.rcu_cpu_stall_suppress_at_boot= [KNL]
+ Suppress RCU CPU stall warning messages and
+ rcutorture writer stall warnings that occur
+ during early boot, that is, during the time
+ before the init task is spawned.
rcupdate.rcu_cpu_stall_timeout= [KNL]
Set timeout for RCU CPU stall warning messages.
@@ -4025,6 +4671,13 @@
only normal grace-period primitives. No effect
on CONFIG_TINY_RCU kernels.
+ rcupdate.rcu_task_ipi_delay= [KNL]
+ Set time in jiffies during which RCU tasks will
+ avoid sending IPIs, starting with the beginning
+ of a given grace period. Setting a large
+ number avoids disturbing real-time workloads,
+ but lengthens grace periods.
+
rcupdate.rcu_task_stall_timeout= [KNL]
Set timeout in jiffies for RCU task stall warning
messages. Disable with a value less than or equal
@@ -4032,12 +4685,6 @@
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>
@@ -4072,9 +4719,48 @@
reboot_cpu is s[mp]#### with #### being the processor
to be used for rebooting.
+ refscale.holdoff= [KNL]
+ Set test-start holdoff period. The purpose of
+ this parameter is to delay the start of the
+ test until boot completes in order to avoid
+ interference.
+
+ refscale.loops= [KNL]
+ Set the number of loops over the synchronization
+ primitive under test. Increasing this number
+ reduces noise due to loop start/end overhead,
+ but the default has already reduced the per-pass
+ noise to a handful of picoseconds on ca. 2020
+ x86 laptops.
+
+ refscale.nreaders= [KNL]
+ Set number of readers. The default value of -1
+ selects N, where N is roughly 75% of the number
+ of CPUs. A value of zero is an interesting choice.
+
+ refscale.nruns= [KNL]
+ Set number of runs, each of which is dumped onto
+ the console log.
+
+ refscale.readdelay= [KNL]
+ Set the read-side critical-section duration,
+ measured in microseconds.
+
+ refscale.scale_type= [KNL]
+ Specify the read-protection implementation to test.
+
+ refscale.shutdown= [KNL]
+ Shut down the system at the end of the performance
+ test. This defaults to 1 (shut it down) when
+ refscale is built into the kernel and to 0 (leave
+ it running) when refscale is built as a module.
+
+ refscale.verbose= [KNL]
+ Enable additional printk() statements.
+
relax_domain_level=
[KNL, SMP] Set scheduler's default relax_domain_level.
- See Documentation/cgroup-v1/cpusets.txt.
+ See Documentation/admin-guide/cgroup-v1/cpusets.rst.
reserve= [KNL,BUGS] Force kernel to ignore I/O ports or memory
Format: <base1>,<size1>[,<base2>,<size2>,...]
@@ -4104,7 +4790,7 @@
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
+ See Documentation/power/swsusp-and-swap-files.rst
resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
read the resume files
@@ -4123,6 +4809,43 @@
during restoration read-only).
retain_initrd [RAM] Keep initrd memory after extraction
+
+ retbleed= [X86] Control mitigation of RETBleed (Arbitrary
+ Speculative Code Execution with Return Instructions)
+ vulnerability.
+
+ AMD-based UNRET and IBPB mitigations alone do not stop
+ sibling threads from influencing the predictions of other
+ sibling threads. For that reason, STIBP is used on pro-
+ cessors that support it, and mitigate SMT on processors
+ that don't.
+
+ off - no mitigation
+ auto - automatically select a migitation
+ auto,nosmt - automatically select a mitigation,
+ disabling SMT if necessary for
+ the full mitigation (only on Zen1
+ and older without STIBP).
+ ibpb - On AMD, mitigate short speculation
+ windows on basic block boundaries too.
+ Safe, highest perf impact. It also
+ enables STIBP if present. Not suitable
+ on Intel.
+ ibpb,nosmt - Like "ibpb" above but will disable SMT
+ when STIBP is not available. This is
+ the alternative for systems which do not
+ have STIBP.
+ unret - Force enable untrained return thunks,
+ only effective on AMD f15h-f17h based
+ systems.
+ unret,nosmt - Like unret, but will disable SMT when STIBP
+ is not available. This is the alternative for
+ systems which do not have STIBP.
+
+ Selecting 'auto' will choose a mitigation method at run
+ time according to the CPU.
+
+ Not specifying this option is equivalent to retbleed=auto.
rfkill.default_state=
0 "airplane mode". All wifi, bluetooth, wimax, gps, fm,
@@ -4197,6 +4920,114 @@
incurs a small amount of overhead in the scheduler
but is useful for debugging and performance tuning.
+ sched_thermal_decay_shift=
+ [KNL, SMP] Set a decay shift for scheduler thermal
+ pressure signal. Thermal pressure signal follows the
+ default decay period of other scheduler pelt
+ signals(usually 32 ms but configurable). Setting
+ sched_thermal_decay_shift will left shift the decay
+ period for the thermal pressure signal by the shift
+ value.
+ i.e. with the default pelt decay period of 32 ms
+ sched_thermal_decay_shift thermal pressure decay pr
+ 1 64 ms
+ 2 128 ms
+ and so on.
+ Format: integer between 0 and 10
+ Default is 0.
+
+ scftorture.holdoff= [KNL]
+ Number of seconds to hold off before starting
+ test. Defaults to zero for module insertion and
+ to 10 seconds for built-in smp_call_function()
+ tests.
+
+ scftorture.longwait= [KNL]
+ Request ridiculously long waits randomly selected
+ up to the chosen limit in seconds. Zero (the
+ default) disables this feature. Please note
+ that requesting even small non-zero numbers of
+ seconds can result in RCU CPU stall warnings,
+ softlockup complaints, and so on.
+
+ scftorture.nthreads= [KNL]
+ Number of kthreads to spawn to invoke the
+ smp_call_function() family of functions.
+ The default of -1 specifies a number of kthreads
+ equal to the number of CPUs.
+
+ scftorture.onoff_holdoff= [KNL]
+ Number seconds to wait after the start of the
+ test before initiating CPU-hotplug operations.
+
+ scftorture.onoff_interval= [KNL]
+ Number seconds to wait between successive
+ CPU-hotplug operations. Specifying zero (which
+ is the default) disables CPU-hotplug operations.
+
+ scftorture.shutdown_secs= [KNL]
+ The number of seconds following the start of the
+ test after which to shut down the system. The
+ default of zero avoids shutting down the system.
+ Non-zero values are useful for automated tests.
+
+ scftorture.stat_interval= [KNL]
+ The number of seconds between outputting the
+ current test statistics to the console. A value
+ of zero disables statistics output.
+
+ scftorture.stutter_cpus= [KNL]
+ The number of jiffies to wait between each change
+ to the set of CPUs under test.
+
+ scftorture.use_cpus_read_lock= [KNL]
+ Use use_cpus_read_lock() instead of the default
+ preempt_disable() to disable CPU hotplug
+ while invoking one of the smp_call_function*()
+ functions.
+
+ scftorture.verbose= [KNL]
+ Enable additional printk() statements.
+
+ scftorture.weight_single= [KNL]
+ The probability weighting to use for the
+ smp_call_function_single() function with a zero
+ "wait" parameter. A value of -1 selects the
+ default if all other weights are -1. However,
+ if at least one weight has some other value, a
+ value of -1 will instead select a weight of zero.
+
+ scftorture.weight_single_wait= [KNL]
+ The probability weighting to use for the
+ smp_call_function_single() function with a
+ non-zero "wait" parameter. See weight_single.
+
+ scftorture.weight_many= [KNL]
+ The probability weighting to use for the
+ smp_call_function_many() function with a zero
+ "wait" parameter. See weight_single.
+ Note well that setting a high probability for
+ this weighting can place serious IPI load
+ on the system.
+
+ scftorture.weight_many_wait= [KNL]
+ The probability weighting to use for the
+ smp_call_function_many() function with a
+ non-zero "wait" parameter. See weight_single
+ and weight_many.
+
+ scftorture.weight_all= [KNL]
+ The probability weighting to use for the
+ smp_call_function_all() function with a zero
+ "wait" parameter. See weight_single and
+ weight_many.
+
+ scftorture.weight_all_wait= [KNL]
+ The probability weighting to use for the
+ smp_call_function_all() function with a
+ non-zero "wait" parameter. See weight_single
+ and weight_many.
+
skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
xtime_lock contention on larger systems, and/or RCU lock
contention on all systems with CONFIG_MAXSMP set.
@@ -4206,20 +5037,16 @@
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.
+ security= [SECURITY] Choose a legacy "major" security module to
+ enable at boot. This has been deprecated by the
+ "lsm=" parameter.
selinux= [SELINUX] Disable or enable SELinux at boot time.
Format: { "0" | "1" }
See security/selinux/Kconfig help text.
0 -- disable.
1 -- enable.
- Default value is set via kernel config option.
- If enabled at boot time, /selinux/disable can be used
- later to disable prior to initial policy load.
+ Default value is 1.
apparmor= [APPARMOR] Disable or enable AppArmor at boot time
Format: { "0" | "1" }
@@ -4257,7 +5084,7 @@
fragmentation. Defaults to 1 for systems with
more than 32MB of RAM, 0 otherwise.
- slub_debug[=options[,slabs]] [MM, SLUB]
+ slub_debug[=options[,slabs][;[options[,slabs]]...] [MM, SLUB]
Enabling slub_debug allows one to determine the
culprit if slab objects become corrupted. Enabling
slub_debug can create guard zones around objects and
@@ -4320,21 +5147,21 @@
softlockup_panic=
[KNL] Should the soft-lockup detector generate panics.
- Format: <integer>
+ Format: 0 | 1
- 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.
+ A value of 1 instructs the soft-lockup detector
+ to panic the machine when a soft-lockup occurs. It is
+ also controlled by the kernel.softlockup_panic sysctl
+ and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the
+ respective build-time switch to that functionality.
softlockup_all_cpu_backtrace=
[KNL] Should the soft-lockup detector generate
backtraces on all cpus.
- Format: <integer>
+ Format: 0 | 1
sonypi.*= [HW] Sony Programmable I/O Control Device driver
- See Documentation/laptops/sonypi.txt
+ See Documentation/admin-guide/laptops/sonypi.rst
spectre_v2= [X86] Control mitigation of Spectre variant 2
(indirect branch speculation) vulnerability.
@@ -4363,8 +5190,13 @@
Specific mitigations can also be selected manually:
retpoline - replace indirect branches
- retpoline,generic - google's original retpoline
- retpoline,amd - AMD-specific minimal thunk
+ retpoline,generic - Retpolines
+ retpoline,lfence - LFENCE; indirect branch
+ retpoline,amd - alias for retpoline,lfence
+ eibrs - enhanced IBRS
+ eibrs,retpoline - enhanced IBRS + Retpolines
+ eibrs,lfence - enhanced IBRS + LFENCE
+ ibrs - use IBRS to protect kernel
Not specifying this option is equivalent to
spectre_v2=auto.
@@ -4410,6 +5242,17 @@
Not specifying this option is equivalent to
spectre_v2_user=auto.
+
+ spec_rstack_overflow=
+ [X86] Control RAS overflow mitigation on AMD Zen CPUs
+
+ off - Disable mitigation
+ microcode - Enable microcode mitigation only
+ safe-ret - Enable sw-only safe RET mitigation (default)
+ ibpb - Enable mitigation by issuing IBPB on
+ kernel entry
+ ibpb-vmexit - Issue IBPB only on VMEXIT
+ (cloud-specific mitigation)
spec_store_bypass_disable=
[HW] Control Speculative Store Bypass (SSB) Disable mitigation
@@ -4467,6 +5310,28 @@
spia_fio_base=
spia_pedr=
spia_peddr=
+
+ split_lock_detect=
+ [X86] Enable split lock detection
+
+ When enabled (and if hardware support is present), atomic
+ instructions that access data across cache line
+ boundaries will result in an alignment check exception.
+
+ off - not enabled
+
+ warn - the kernel will emit rate limited warnings
+ about applications triggering the #AC
+ exception. This mode is the default on CPUs
+ that supports split lock detection.
+
+ fatal - the kernel will send SIGBUS to applications
+ that trigger the #AC exception.
+
+ If an #AC exception is hit in the kernel or in
+ firmware (i.e. not while executing in user mode)
+ the kernel will oops in either "warn" or "fatal"
+ mode.
srbds= [X86,INTEL]
Control the Special Register Buffer Data Sampling
@@ -4528,6 +5393,12 @@
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.
+
+ stack_depot_disable= [KNL]
+ Setting this to true through kernel command line will
+ disable the stack depot thereby saving the static memory
+ consumed by the stack hash table. By default this is set
+ to false.
stacktrace [FTRACE]
Enabled the stack tracer on boot up.
@@ -4603,10 +5474,15 @@
/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
is set. Default value is 5.
+ svm= [PPC]
+ Format: { on | off | y | n | 1 | 0 }
+ This parameter controls use of the Protected
+ Execution Facility on pSeries.
+
swapaccount=[0|1]
[KNL] Enable accounting of swap in memory resource
controller if no parameter or 1 is given or disable
- it if 0 is given (See Documentation/cgroup-v1/memory.txt)
+ it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)
swiotlb= [ARM,IA-64,PPC,MIPS,X86]
Format: { <int> | force | noforce }
@@ -4616,6 +5492,15 @@
noforce -- Never use bounce buffers (for debugging)
switches= [HW,M68k]
+
+ sysctl.*= [KNL]
+ Set a sysctl parameter, right before loading the init
+ process, as if the value was written to the respective
+ /proc/sys/... file. Both '.' and '/' are recognized as
+ separators. Unrecognized parameters and invalid values
+ are reported in the kernel log. Sysctls registered
+ later by a loaded module cannot be set this way.
+ Example: sysctl.vm.swappiness=40
sysfs.deprecated=0|1 [KNL]
Enable/disable old style sysfs layout for old udev
@@ -4636,7 +5521,7 @@
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
+ cache size. See Documentation/networking/ip-sysctl.rst
"tcp_no_metrics_save" section for more details.
tdfx= [HW,DRM]
@@ -4681,27 +5566,6 @@
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
@@ -4715,6 +5579,17 @@
Specify if the kernel should ignore (off)
topology updates sent by the hypervisor to this
LPAR.
+
+ torture.disable_onoff_at_boot= [KNL]
+ Prevent the CPU-hotplug component of torturing
+ until after init has spawned.
+
+ torture.ftrace_dump_at_shutdown= [KNL]
+ Dump the ftrace buffer at torture-test shutdown,
+ even if there were no errors. This can be a
+ very costly operation when many torture tests
+ are running concurrently, especially on systems
+ with rotating-rust storage.
tp720= [HW,PS2]
@@ -4805,6 +5680,16 @@
[x86] unstable: mark the TSC clocksource as unstable, this
marks the TSC unconditionally unstable at bootup and
avoids any further wobbles once the TSC watchdog notices.
+ [x86] nowatchdog: disable clocksource watchdog. Used
+ in situations with strict latency requirements (where
+ interruptions from clocksource watchdog are not
+ acceptable).
+
+ tsc_early_khz= [X86] Skip early TSC calibration and use the given
+ value instead. Useful when the early TSC frequency discovery
+ procedure is not reliable, such as on overclocked systems
+ with CPUID.16h support and partial CPUID.15h support.
+ Format: <unsigned int>
tsx= [X86] Control Transactional Synchronization
Extensions (TSX) feature in Intel processors that
@@ -4904,7 +5789,8 @@
usbcore.authorized_default=
[USB] Default USB device authorization:
(default -1 = authorized except for wireless USB,
- 0 = not authorized, 1 = authorized)
+ 0 = not authorized, 1 = authorized, 2 = authorized
+ if device connected to internal port)
usbcore.autosuspend=
[USB] The autosuspend time delay (in seconds) used
@@ -5111,7 +5997,7 @@
vector=percpu: enable percpu vector domain
video= [FB] Frame buffer configuration
- See Documentation/fb/modedb.txt.
+ See Documentation/fb/modedb.rst.
video.brightness_switch_enabled= [0,1]
If set to 1, on receiving an ACPI notify event
@@ -5139,11 +6025,23 @@
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.
+ See Documentation/x86/boot.rst and
+ Documentation/admin-guide/svga.rst.
Use vga=ask for menu.
This is actually a boot loader parameter; the value is
passed to the kernel using a special protocol.
+
+ vm_debug[=options] [KNL] Available with CONFIG_DEBUG_VM=y.
+ May slow down system boot speed, especially when
+ enabled on systems with a large amount of memory.
+ All options are enabled by default, and this
+ interface is meant to allow for selectively
+ enabling or disabling specific virtual memory
+ debugging features.
+
+ Available options are:
+ P Enable page structure init time poisoning
+ - Disable all of the above options
vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
size of <nn>. This can be used to increase the
@@ -5173,7 +6071,12 @@
targets for exploits that can control RIP.
emulate [default] Vsyscalls turn into traps and are
- emulated reasonably safely.
+ emulated reasonably safely. The vsyscall
+ page is readable.
+
+ xonly Vsyscalls turn into traps and are
+ emulated reasonably safely. The vsyscall
+ page is not readable.
none Vsyscalls don't work at all. This makes
them quite hard to use for exploits but
@@ -5229,9 +6132,17 @@
Default: 3 = cyan.
watchdog timers [HW,WDT] For information on watchdog timers,
- see Documentation/watchdog/watchdog-parameters.txt
+ see Documentation/watchdog/watchdog-parameters.rst
or other driver-specific files in the
Documentation/watchdog/ directory.
+
+ watchdog_thresh=
+ [KNL]
+ Set the hard lockup detector stall duration
+ threshold in seconds. The soft lockup detector
+ threshold is set to twice the value. A value of 0
+ disables both lockup detectors. Default is 10
+ seconds.
workqueue.watchdog_thresh=
If CONFIG_WQ_WATCHDOG is configured, workqueue can
@@ -5311,18 +6222,32 @@
panic() code such as dumping handler.
xen_nopvspin [X86,XEN]
- Disables the ticketlock slowpath using Xen PV
- optimizations.
+ Disables the qspinlock slowpath using Xen PV optimizations.
+ This parameter is obsoleted by "nopvspin" parameter, which
+ has equivalent effect for XEN platform.
xen_nopv [X86]
Disables the PV optimizations forcing the HVM guest to
run as generic HVM guest with no PV drivers.
+ This option is obsoleted by the "nopv" option, which
+ has equivalent effect for XEN platform.
+
+ xen_no_vector_callback
+ [KNL,X86,XEN] Disable the vector callback for Xen
+ event channel interrupts.
xen_scrub_pages= [XEN]
Boolean option to control scrubbing pages before giving them back
to Xen, for use by other domains. Can be also changed at runtime
with /sys/devices/system/xen_memory/xen_memory0/scrub_pages.
Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.
+
+ xen_timer_slop= [X86-64,XEN]
+ Set the timer slop (in nanoseconds) for the virtual Xen
+ timers (default is 100000). This adjusts the minimum
+ delta of virtualized Xen timers, where lower values
+ improve timer resolution at the expense of processing
+ more timer interrupts.
xen.balloon_boot_timeout= [XEN]
The time (in seconds) to wait before giving up to boot
@@ -5339,11 +6264,56 @@
After which time (jiffies) the event handling loop
should start to delay EOI handling. Default is 2.
+ xen.fifo_events= [XEN]
+ Boolean parameter to disable using fifo event handling
+ even if available. Normally fifo event handling is
+ preferred over the 2-level event handling, as it is
+ fairer and the number of possible event channels is
+ much higher. Default is on (use fifo events).
+
+ nopv= [X86,XEN,KVM,HYPER_V,VMWARE]
+ Disables the PV optimizations forcing the guest to run
+ as generic guest with no PV drivers. Currently support
+ XEN HVM, KVM, HYPER_V and VMWARE guest.
+
+ nopvspin [X86,XEN,KVM]
+ Disables the qspinlock slow path using PV optimizations
+ which allow the hypervisor to 'idle' the guest on lock
+ contention.
+
xirc2ps_cs= [NET,PCMCIA]
Format:
<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
+
+ xive= [PPC]
+ By default on POWER9 and above, the kernel will
+ natively use the XIVE interrupt controller. This option
+ allows the fallback firmware mode to be used:
+
+ off Fallback to firmware control of XIVE interrupt
+ controller on both pseries and powernv
+ platforms. Only useful on POWER9 and above.
xhci-hcd.quirks [USB,KNL]
A hex value specifying bitmask with supplemental xhci
host controller quirks. Meaning of each bit can be
consulted in header drivers/usb/host/xhci.h.
+
+ xmon [PPC]
+ Format: { early | on | rw | ro | off }
+ Controls if xmon debugger is enabled. Default is off.
+ Passing only "xmon" is equivalent to "xmon=early".
+ early Call xmon as early as possible on boot; xmon
+ debugger is called from setup_arch().
+ on xmon debugger hooks will be installed so xmon
+ is only called on a kernel crash. Default mode,
+ i.e. either "ro" or "rw" mode, is controlled
+ with CONFIG_XMON_DEFAULT_RO_MODE.
+ rw xmon debugger hooks will be installed so xmon
+ is called only on a kernel crash, mode is write,
+ meaning SPR registers, memory and, other data
+ can be written using xmon commands.
+ ro same as "rw" option above but SPR registers,
+ memory, and other data can't be written using
+ xmon commands.
+ off xmon is disabled.
--
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