Lines Matching +full:no +full:- +full:poll +full:- +full:on +full:- +full:init
14 Format: { force | on | off | strict | noirq | rsdt |
16 force -- enable ACPI if default was off
17 on -- enable ACPI but allow fallback to DT [arm64,riscv64]
18 off -- disable ACPI if default was on
19 noirq -- do not use ACPI for IRQ routing
20 strict -- Be less tolerant of platforms that are not
22 rsdt -- prefer RSDT over (default) XSDT
23 copy_dsdt -- copy DSDT to memory
24 nospcr -- disable console in ACPI SPCR table as
25 default _serial_ console on ARM64
26 For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or
28 For RISCV64, ONLY "acpi=off", "acpi=on" or "acpi=force"
41 If set to vendor, prefer vendor-specific driver
73 Documentation/firmware-guide/acpi/debug.rst for more information about
89 { strict | lax | no }
101 no: ACPI OperationRegions are not marked as reserved,
102 no further checks are performed.
131 Format: <byte> or <bitmap-list>
134 Disable auto-serialization of AML methods
137 auto-serialization feature.
155 Ignore the ACPI-based watchdog interface (WDAT) and let
160 on machines running EFI runtime service to boot the
170 row to make it take effect on the platform firmware).
176 acpi_osi=! # disable all built-in OS vendor
178 acpi_osi=!! # enable all built-in OS vendor
240 For broken nForce2 BIOS resulting in XT-PIC timer.
246 See Documentation/power/video.rst for information on
249 as soon as the kernel's real-mode entry point is called.
255 on docking. So the default behaviour is to allow resume
267 on resume from S1/S3 (which is against the ACPI spec,
287 See Documentation/sound/alsa-configuration.rst
294 align_va_addr= [X86-64]
297 gives you up to 3% performance improvement on AMD F15h
299 CPU-intensive style benchmark, and it can vary highly in
300 a microbenchmark depending on workload and compiler.
302 32: only for 32-bit processes
303 64: only for 64-bit processes
304 on: enable for both 32- and 64-bit processes
305 off: disable for both 32- and 64-bit processes
308 Allocate the ftrace snapshot buffer on boot up when the
310 and you need to use tracing_snapshot() on boot up, and
315 Allow execve() of 32-bit applications and setting of the
316 PER_LINUX32 personality on systems where only a strict
317 subset of the CPUs support 32-bit EL0. When this
318 parameter is present, the set of CPUs supporting 32-bit
320 and hot-unplug operations may be restricted.
322 See Documentation/arch/arm64/asymmetric-32bit.rst for more
325 amd_iommu= [HW,X86-64]
328 fullflush - Deprecated, equivalent to iommu.strict=1
329 off - do not initialize any AMD IOMMU found in
331 force_isolation - Force device isolation for all
336 force_enable - Force enable the IOMMU on platforms known
339 pgtbl_v1 - Use v1 page table for DMA-API (Default).
340 pgtbl_v2 - Use v2 page table for DMA-API.
341 irtcachedis - Disable Interrupt Remapping Table (IRT) caching.
342 nohugepages - Limit page-sizes used for v1 page-tables
344 v2_pgsizes_only - Limit page-sizes used for v1 page-tables
348 amd_iommu_dump= [HW,X86-64]
354 amd_iommu_intr= [HW,X86-64]
357 legacy - Use legacy interrupt remapping mode.
358 vapic - Use virtual APIC mode, which allows IOMMU
360 This mode requires kvm-amd.avic=1.
389 Disable amd-pstate preferred core.
402 Power management functions (SPARCstation-4/5 + deriv.)
404 Disable APC CPU standby support. SPARCstation-Fox does
405 not play well with APC CPU idle - disable it if you have
412 when initialising the APIC and IO-APIC components.
413 For X86-32, this can also be used to specify an APIC
436 0 -- disable.
437 1 -- enable.
440 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
471 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
479 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
488 audit= [KNL] Enable the audit sub-system
489 Format: { "0" | "1" | "off" | "on" }
490 0 | off - kernel audit is disabled and can not be
492 unset - kernel audit is initialized but disabled and
494 1 | on - kernel audit is initialized and partially
504 bau= [X86_UV] Enable the BAU on SGI UV. The default
507 0 - Disable the BAU.
508 1 - Enable the BAU.
509 unset - Disable the BAU.
541 Disable BERT OS support on buggy BIOSes.
547 embedded devices based on command line input.
548 See Documentation/block/cmdline-partition.rst
562 See Documentation/admin-guide/bootconfig.rst
567 bttv.pll= See Documentation/admin-guide/media/bttv.rst
576 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
588 ca_keys= [KEYS] This parameter identifies a specific key(s) on
595 inclusive. See arch/mips/include/asm/pgtable-bits.h
605 - foo isn't auto-mounted if you mount all cgroups in
607 - foo isn't visible as an individually mountable
609 - if foo is an optional feature then the feature is
615 Specifying "pressure" disables per-cgroup pressure
633 nosocket -- Disable socket memory accounting.
634 nokmem -- Disable kernel memory accounting.
635 nobpf -- Disable BPF memory accounting.
640 0 -- check protection applied by kernel (includes
642 1 -- check protection requested by application.
654 numbers X. Note the Linux-specific bits are not necessarily
655 stable over kernel options, but the vendor-specific
675 force such clocks to be always-on nor does it reserve
677 debug and development, but should not be needed on a
679 information, see Documentation/driver-api/clk.rst.
681 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
692 Some clocksource names to choose from, depending on
698 [X86-32] pit,hpet,tsc;
699 scx200_hrt on Geode; cyclone on IBM x440
705 [X86-64] hpet,tsc
711 architected timer so that code using WFE-based polling
712 loops can be debugged more effectively on production
723 no replacement if the same CPU is chosen twice.
725 clocksource-wdtest.holdoff= [KNL]
731 cma=nn[MG]@[start[MG][-end[MG]]]
742 Sets the size of kernel per-numa memory area for
744 per-numa CMA altogether. And If this option is not
746 With per-numa CMA enabled, DMA users on node nid will
757 With numa CMA enabled, DMA users on node nid will
762 cmo_free_hint= [PPC] Format: { yes | no }
773 com20020= [HW,NET] ARCnet - COM20020 chipset
777 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
781 ARCnet - COM90xx chipset (memory-mapped buffers)
789 When set to true, drop data on the 3215 console when
795 terminal emulator is active. If no 3270 terminal
796 emulator is used, this parameter has no effect.
810 See Documentation/admin-guide/serial-console.rst for more
816 Use the specified serial port on the serial core bus.
825 $ ls -d /sys/bus/serial-base/devices/*:*.*/tty/*
826 /sys/bus/serial-base/devices/00:04:0.0/tty/ttyS0
832 the console may be desired for console output early on.
839 Start an early, polled-mode console on the 8250/16550
842 MMIO inter-register address stride is either 8-bit
843 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
847 the h/w is not re-initialized.
855 This must be the only console= parameter used on the
866 By default we print messages on consoles in
868 printed, depending on CONFIG_PRINTK_TIME or
874 syscall, or to executing "dmesg -S --raw" or to reading
898 disable the cpuidle sub-system
904 disable the cpufreq sub-system
912 [X86,EARLY] Delay for N microsec between assert and de-assert
913 of APIC INIT to start processors. This delay occurs
914 on every CPU online, such as boot, and resume from suspend.
921 the parameter has no effect.
924 Run kdump after running panic-notifiers and dumping
937 [KNL, X86-64, ARM64, RISCV, LoongArch] Select a region
940 See Documentation/admin-guide/kdump/kdump.rst for further details.
943 [KNL] Same as above, but depends on the memory
945 start-[end] where start and end are both
947 Documentation/admin-guide/kdump/kdump.rst for an example.
950 [KNL, X86-64, ARM64, RISCV, LoongArch] range could be
958 [KNL, X86-64, ARM64, RISCV, LoongArch] range under 4G.
961 crash on system that require some amount of low memory,
964 for 32-bit devices won't run out. Kernel would try to allocate
967 --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
968 --> arm64: 128MiB
969 --> riscv: 128MiB
970 --> loongarch: 128MiB
978 [KNL] Disable crypto self-tests
986 csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
987 function call handling. When switched on,
992 option depends on the CSD_LOCK_WAIT_DEBUG_DEFAULT
1001 See also Documentation/input/devices/joystick-parport.rst
1011 insecure, please do not use on production kernels.
1014 [KNL] verbose locking self-tests
1017 self-tests.
1019 (no extra messages), setting it to -1 (all bits set)
1020 will print _a_lot_ more information - normally only
1051 on: enable the feature
1055 Format: { on, no-mount, off }
1056 on: All functions are enabled.
1057 no-mount:
1062 get a -EPERM as result when trying to register files
1066 Default value is set in build-time with a kernel configuration.
1078 Documentation/admin-guide/mm/hugetlbpage.rst.
1083 deferred probe to give up waiting on dependencies to
1089 dump out devices still on the deferred probe list after
1092 delayacct [KNL] Enable per-task delay accounting
1096 indicates that the driver is running on unsupported
1119 Format: { on | off | def_only | inf_only | always }
1120 on: s390 zlib hardware support for compression on
1122 off: No s390 zlib hardware support
1124 only (compression on level 1)
1127 always: Same as 'on' but ignores the selected compression
1140 Dynamically disable ZONE_DMA32 on kernels compiled with
1147 Disable RADIX MMU mode on POWER9
1167 memory out of your available memory pool based on
1182 entries for DMA-API debugging code. One entry is
1183 required per DMA-API allocation. Use this if the
1184 DMA-API debugging code disables itself because the
1188 With this option the DMA-API debugging driver
1202 on: Turns ON the mitigation.
1212 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
1223 panels may send no or incorrect EDID data sets.
1230 data set with no connector name will be used for
1237 Control how the dt_cpu_ftrs device-tree binding is
1245 Dump name and content of EFI device properties on
1247 what data is available or for reverse-engineering.
1252 Documentation/admin-guide/dynamic-debug-howto.rst
1262 When used with no options, the early console is
1263 determined by stdout-path property in device tree's
1268 Start an early, polled-mode console on a Cadence
1279 Start an early, polled-mode console on the 8250/16550
1281 MMIO inter-register address stride is either 8-bit
1282 (mmio) or 32-bit (mmio32 or mmio32be).
1292 Start an early, polled-mode console on a pl011 serial
1296 the driver will use only 32-bit accessors to read/write
1300 Start an early console on a litex serial port at the
1305 Start an early, polled-mode console on a meson serial
1311 Start an early, polled-mode console on an msm serial
1317 Start an early, polled-mode console on an msm serial
1323 Start an early, polled-mode console on a serial port
1329 Start an early, polled-mode console on a serial port
1335 Use RISC-V SBI (Supervisor Binary Interface) for early
1347 on Samsung SoCs, requires selecting proper type and
1353 Start an early, polled-mode console on a lantiq serial
1361 found on Freescale Vybrid and QorIQ LS1021A processors.
1367 Start an early, polled-mode, output-only console on the
1372 Start an early, polled-mode console on the
1378 Start an early, polled-mode console on a Qualcomm
1384 Start an early, unaccelerated console on the EFI
1385 memory mapped framebuffer (if available). On cache
1386 coherent non-x86 systems that use system memory for
1420 on some architectures (x86 and arm at least) by
1435 The sclp output can only be used on s390.
1437 The bios output can only be used on SuperH.
1444 Format: {"on" | "off" | "force"}
1445 on: enable EDAC to report H/W event. May be overridden
1449 default: on.
1452 Format: {"off" | "on" | "skip[mbr]"}
1459 disable_early_pci_dma: disable the busmaster bit on all
1473 on all PCI bridges while in the EFI boot stub
1485 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1502 elanfreq= [X86-32]
1510 See Documentation/admin-guide/kdump/kdump.rst for details.
1520 (in particular on some ATI chipsets).
1526 0 -- permissive (log only, no denials).
1527 1 -- enforcing (deny and log).
1554 might take longer, especially on systems with a lot of
1563 See also Documentation/fault-injection/.
1567 See Documentation/admin-guide/sysctl/net.rst for
1571 See Documentation/admin-guide/blockdev/floppy.rst.
1573 forcepae [X86-32]
1580 fred= [X86-64]
1582 Format: { on | off }
1583 on: enable FRED when it's present.
1592 [FTRACE] On boot up, a snapshot will be taken of the
1610 [FTRACE] will dump the trace buffers on oops.
1611 If no parameter is passed, ftrace will dump global
1617 instance supports only dump on CPU that triggered the
1623 on CPU that triggered the oops.
1627 The above will dump global buffer on all CPUs, the
1628 buffer of "foo" instance on all CPUs and the buffer
1629 of "bar" instance on CPU that triggered the oops.
1631 ftrace_filter=[function-list]
1633 tracer at boot up. function-list is a comma-separated
1638 ftrace_notrace=[function-list]
1640 function-list. This list can be changed at run time
1644 ftrace_graph_filter=[function-list]
1647 function-list is a comma-separated list of functions
1651 ftrace_graph_notrace=[function-list]
1653 function-list. This list is a comma-separated list of
1661 in the tracefs tracing directory. default: 0 (no limit)
1672 Format: { off | permissive | on | rpm }
1673 off -- Don't create device links from firmware info.
1674 permissive -- Create device links from firmware info
1677 on -- Create device links from firmware info and use it
1679 rpm -- Like "on", but also use to order runtime PM.
1683 dependencies. This only applies for fw_devlink=on|rpm.
1692 strict -- Default. Continue waiting on consumers to
1694 timeout -- Give up waiting on consumers and call
1695 sync_state() on any devices that haven't yet
1704 See also Documentation/input/devices/joystick-parport.rst
1708 gart_fix_e820= [X86-64,EARLY] disable the fix e820 for K8 GART
1709 Format: off | on
1710 default: on
1722 disabled. On systems without the microcode mitigation
1726 microcode mitigation. No effect if the microcode
1732 gcov_persist= [GCOV] When non-zero (default), profiling data for
1739 Don't use this when you are not running on the
1742 gpio-mockup.gpio_mockup_ranges
1745 gpio-mockup.gpio_mockup_named_lines
1777 against bounds-checking flaws in the kernel's
1779 on Perform hardened usercopy checks (default).
1783 [KNL] Should the hard-lockup detector generate
1784 backtraces on all cpus.
1788 are distributed across NUMA nodes. Defaults on
1789 for 64-bit NUMA, off otherwise.
1790 Format: 0 | 1 (for off | on)
1797 corresponding firmware-first mode error processing
1804 no Disable hibernation and resume.
1805 protect_image Turn on image protection during restoration
1807 during restoration read-only).
1821 size of <nn>. This works even on boxes that have no
1823 size on bigger boxes.
1826 Valid parameters: "on", "off"
1827 Default: "on"
1844 hpet= [X86-32,HPET] option to control HPET usage
1858 If this is the first HugeTLB parameter on the command
1861 number of pages to allocate per-node can be specified.
1862 See also Documentation/admin-guide/mm/hugetlbpage.rst.
1873 Documentation/admin-guide/mm/hugetlbpage.rst.
1884 boot-time allocation of gigantic hugepages is skipped.
1892 Format: { on | off (default) }
1894 on: enable HVO
1898 the default is on.
1912 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1918 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1929 on lock contention.
1938 Set device-properties for ACPI-enumerated I2C-attached
1939 touchscreen, to e.g. fix coordinates of upside-down
1947 Omit "=<val>" entirely Set a boolean device-property
1948 Unsigned number Set a u32 device-property
1949 Anything else Set a string device-property
1952 i2c_touchscreen_props=GDIX1001:touchscreen-inverted-x:
1953 touchscreen-inverted-y
1955 i2c_touchscreen_props=MSSL1680:touchscreen-size-x=1920:
1956 touchscreen-size-y=1080:touchscreen-inverted-y:
1957 firmware-name=gsl1680-vendor-model.fw:silead,home-button
1962 (disabled by default, and as a pre-condition
1964 i8042.direct [HW] Put keyboard port into non-translated mode
1977 i8042.reset [HW] Reset the controller during init, cleanup and
1978 suspend-to-ram transitions, only during s2r
1983 Default: only on s2r transitions on x86; most other
2002 -1 -- never invert brightness
2003 0 -- machine default
2004 1 -- force brightness inversion
2006 ia32_emulation= [X86-64]
2008 When true, allows loading 32-bit programs and executing 32-bit
2017 Format: idle=poll, idle=halt, idle=nomwait
2018 Poll forces a polling idle loop that can slightly
2024 idle=nomwait: Disable mwait for CPU C-states
2042 based on the IEEE 754 NaN encoding(s) supported by
2052 legacy only accept legacy-NaN binaries, if supported
2054 2008 only accept 2008-NaN binaries, if supported
2062 encodings, so if no FPU hardware is present or it has
2065 'relaxed' straps the emulator for both legacy-NaN and
2066 2008-NaN, whereas 'strict' enables legacy-NaN only on
2067 legacy processors and both NaN encodings on MIPS32 or
2075 Ignore loglevel setting - this will print /all/
2124 firmware, policy, etc) based on file signatures.
2127 verification failure also on privileged mounted
2142 Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
2143 "ima-sigv2" }
2144 Default: "ima-ng"
2155 ahash performance varies for different data sizes on
2163 ahash performance varies for different chunk sizes on
2171 on: Enable mitigation (default).
2177 stuff: Deploy RSB-fill mitigation when retpoline is
2182 Documentation/admin-guide/hw-vuln/indirect-target-selection.rst
2184 init= [KNL]
2186 Run specified binary instead of /sbin/init as init
2193 initcall_blacklist= [KNL] Do not execute a comma-separated list of
2194 initcall functions. Useful for debugging built-in
2239 0 -- basic integrity auditing messages. (Default)
2240 1 -- additional integrity auditing messages.
2243 on
2267 By default, tboot will force Intel IOMMU on, which
2268 could harm performance of some high-throughput
2276 0 disables intel_idle and fall back on acpi_idle.
2277 1 to 9 specify maximum depth of C-state.
2286 algorithms for p-state selection. There are two
2287 P-state selection algorithms provided by
2290 on whether or not the hardware managed P-states
2292 and possibly on the processor model.
2297 used along with the hardware-managed P-states (HWP)
2300 Enable intel_pstate on systems that prohibit it by default
2301 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2302 instead of acpi-cpufreq may disable platform features, such
2303 as thermal controls and power capping, that rely on ACPI
2304 P-States information being indicated to OSPM and therefore
2307 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2312 Only load intel_pstate on systems which support
2318 then this feature is turned on by default.
2320 Allow per-logical-CPU P-State performance control limits using
2323 intremap= [X86-64,Intel-IOMMU,EARLY]
2324 on enable Interrupt Remapping (default)
2328 BIOS x2APIC opt-out request will be ignored
2354 0 - Try to allocate a 32-bit DMA address first, before
2356 1 - Allocate directly from the full usable range,
2358 greater than 32-bit addressing.
2362 0 - Lazy mode.
2368 1 - Strict mode.
2371 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2372 Note: on x86, strict mode specified via one of the
2373 legacy driver-specific options takes precedence.
2378 0 - Use IOMMU translation for DMA.
2379 1 - Bypass the IOMMU for DMA.
2380 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2382 io7= [HW] IO7 for Marvel-based Alpha systems
2390 Alternate port 0xed based delay (needed on some systems)
2394 No delay
2397 See Documentation/admin-guide/nfs/nfsroot.rst.
2433 Enables support for pseudo-NMIs in the kernel. This
2452 [Deprecated - use cpusets instead]
2453 Format: [flag-list,]<cpu-list>
2467 NOTE: by default the global workqueue runs on all CPUs,
2484 "number of CPUs in system - 1".
2499 so that IO submitted on the housekeeping CPU
2503 CPUs then this parameter has no effect on the
2505 only delivered when tasks running on those
2506 isolated CPUs submit IO. IO submitted on
2507 housekeeping CPUs has no influence on those
2510 The format of <cpu-list> is described above.
2514 ivrs_ioapic [HW,X86-64]
2515 Provide an override to the IOAPIC-ID<->DEVICE-ID
2519 For example, to map IOAPIC-ID decimal 10 to
2525 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2528 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2532 ivrs_hpet [HW,X86-64]
2533 Provide an override to the HPET-ID<->DEVICE-ID
2537 For example, to map HPET-ID decimal 10 to
2543 * To map HPET-ID decimal 0 to PCI device 00:14.0
2546 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2550 ivrs_acpihid [HW,X86-64]
2551 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2555 For example, to map UART-HID:UID AMD0020:0 to
2561 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2564 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2573 report on every invalid memory access. Without this
2588 the kernel for non-movable allocations. The requested
2598 subsystem. Note that allocations like PTEs-from-HighMem
2606 for non-movable allocations and remaining memory is used
2611 Format: <Controller#>[,poll interval]
2613 port as it is probed via PCI. The poll interval is
2615 each poll cycle to the debug port in case you need
2617 gdb or control-c on the dbgp connection. When
2618 not using this parameter you use sysrq-g to break into
2623 or a supported polling keyboard driver (non-usb).
2650 Configure the RouterBoard 532 series on-chip
2653 kmemleak= [KNL,EARLY] Boot-time kmemleak enable/disable
2654 Valid arguments: on, off
2655 Default: on
2659 kprobe_event=[probe-list]
2661 The probe-list is a semicolon delimited list of probe
2664 For example, to add a kprobe event on vfs_read with
2674 Default: enabled on cores which need mitigation.
2691 execution by eliminating the write-protection faults
2700 The behavior of eager page splitting depends on whether
2703 split when dirty logging is enabled on that memslot. If
2710 Default is Y (on).
2718 virtualization on-demand when creating and destroying
2719 VMs, i.e. on the 0=>1 and 1=>0 transitions of the
2726 is that doing so may interfere with using out-of-tree
2737 auto : Deploy workaround based on the presence of
2753 back to huge pages. If the value is a non-zero N, KVM will
2756 on the ratio, such that a page is zapped after 1 hour on average.
2758 kvm-amd.nested= [KVM,AMD] Control nested virtualization feature in
2761 kvm-amd.npt= [KVM,AMD] Control KVM's use of Nested Page Tables,
2762 a.k.a. Two-Dimensional Page Tables. Default is 1
2766 kvm-arm.hyp_lm_size_mb=
2769 memory than this into pKVM stage-1 at run-time may be fatal.
2771 kvm-arm.mode=
2777 nvhe: Standard nVHE-based mode, without support for
2780 protected: nVHE-based mode with support for guests whose
2785 nested: VHE-based mode with support for nested
2789 Defaults to VHE/nVHE based on hardware support. Setting
2794 kvm-arm.protected_modules=
2799 kvm-arm.mode=protected.
2801 kvm-arm.protected_prefault=
2805 kvm-arm.vgic_v3_group0_trap=
2806 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-0
2809 kvm-arm.vgic_v3_group1_trap=
2810 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-1
2813 kvm-arm.vgic_v3_common_trap=
2817 kvm-arm.vgic_v4_enable=
2821 kvm-arm.wfe_trap_policy=
2830 kvm-arm.wfi_trap_policy=
2847 kvm-intel.ept= [KVM,Intel] Control KVM's use of Extended Page Tables,
2848 a.k.a. Two-Dimensional Page Tables. Default is 1
2852 kvm-intel.emulate_invalid_guest_state=
2854 state. Ignored if kvm-intel.enable_unrestricted_guest=1,
2860 kvm-intel.flexpriority=
2865 kvm-intel.nested=
2869 kvm-intel.unrestricted_guest=
2875 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2876 CVE-2018-3620.
2880 always: L1D cache flush on every VMENTER.
2881 cond: Flush L1D on VMENTER only when the code between
2887 kvm-intel.vpid= [KVM,Intel] Control KVM's use of Virtual Processor
2907 on - enable the interface for the mitigation
2909 l1tf= [X86,EARLY] Control mitigation of the L1TF vulnerability on
2967 RAM limit restriction on both hypervisor and
2972 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2978 lapic [X86-32,APIC,EARLY] Enable the local APIC even if BIOS
2982 value for LAPIC timer one-shot implementation. Default
3005 libata.force= [LIBATA] Force configurations. The format is a comma-
3009 printed on console by libata. If the whole ID part is
3017 first fan-out link behind PMP device. It does not
3022 as there is no ambiguity, shortcut notation is allowed.
3031 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
3038 * rstonce: only attempt one reset during hot-unplug
3041 * [no]dbdelay: Enable or disable the extra 200ms delay
3045 * [no]ncq: Turn on or off NCQ.
3047 * [no]ncqtrim: Enable or disable queued DSM TRIM.
3049 * [no]ncqati: Enable or disable NCQ trim on ATI chipset.
3051 * [no]trim: Enable or disable (unqueued) TRIM.
3057 * [no]dma: Turn on or off DMA transfers.
3064 * [no]dmalog: Enable or disable the use of the
3067 * [no]iddevlog: Enable or disable access to the
3070 * [no]logdir: Enable or disable access to the general
3081 * external: Mark port as external (hotplug-capable).
3083 * [no]lpm: Enable or disable link power management.
3085 * [no]setxfer: Indicate if transfer speed mode setting
3088 * [no]fua: Disable or enable FUA (Force Unit Access)
3135 Specify the number of self-propagating call_rcu()
3143 occasional long-duration lock hold time. Defaults
3150 Note that this parameter is ineffective on types
3154 Set the number of locking read-acquisition kthreads.
3155 Defaults to being automatically set based on the
3159 Set the number of locking write-acquisition kthreads.
3162 Set time (s) after boot for CPU-hotplug testing.
3165 Set time (s) between CPU-hotplug operations, or
3166 zero to disable CPU-hotplug testing.
3169 Do periodic testing of real-time lock priority
3174 non-real-time spinlocks, due to their disabling
3175 of preemption. Note that non-realtime mutexes
3184 On the other hand, the duration of each boost
3188 Set task-shuffle interval (jiffies). Shuffling
3189 tasks allows some CPUs to go into dyntick-idle
3194 is useful for hands-off automated testing.
3202 five seconds, wait for five seconds, and so on.
3213 Run the write-side locktorture kthreads at
3214 sched_set_fifo() real-time priority.
3232 7 (KERN_DEBUG) debug-level messages
3241 depending on the number of CPUs. See init/Kconfig
3244 logo.nologo [FB] Disables display of the built-in Linux logo.
3262 an IEEE 1284-compliant printer is attached; if
3268 time-consuming boot-time autodetection (up to 250 ms per
3272 on SMP systems the preset will be applied to all CPUs,
3288 Example: machtype=lemote-yeeloong-2f-7inch
3300 (loop.max_loop) unconditionally pre-created at init time. The default
3303 devices can be requested on-demand with the
3304 /dev/loop-control interface.
3306 mce [X86-32] Machine Check Exception
3308 mce=option [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
3311 See Documentation/admin-guide/md.rst.
3318 Control mitigation for the Micro-architectural Data
3333 full - Enable MDS mitigation on vulnerable CPUs
3334 full,nosmt - Enable MDS mitigation and disable
3335 SMT on vulnerable CPUs
3336 off - Unconditionally disable MDS mitigation
3338 On TAA-affected machines, mds=off can be prevented by
3347 For details see: Documentation/admin-guide/hw-vuln/mds.rst
3362 [ARC,MICROBLAZE] - the limit applies only to low memory,
3365 [ARM64] - only limits memory covered by the linear
3378 [ARM,MIPS,EARLY] - override the memory layout
3383 multiple mem= parameters on the command line.
3385 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
3392 per-device physically contiguous DMA buffers.
3400 See Documentation/admin-guide/mm/memory-hotplug.rst.
3404 Such memmap=exactmap lines can be constructed based on
3425 Example: Exclude memory from 0x18690000-0x1869ffff
3439 memmap=<size>%<offset>-<oldtype>+<newtype>
3441 from <oldtype> to <newtype>. If "-<oldtype>" is left
3456 repeatable BIOS-originated corruption always
3473 Format: {on | off (default)}
3482 has some implication on large (e.g. GB)
3500 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
3501 Valid arguments: on, off
3503 mem_encrypt=on: Activate SME
3506 Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
3507 for details on when memory encryption can be activated.
3510 s2idle - Suspend-To-Idle
3511 shallow - Power-On Suspend or equivalent (if supported)
3512 deep - Suspend-To-RAM or equivalent (if supported)
3513 See Documentation/admin-guide/pm/sleep-states.rst.
3515 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
3531 0 - The attached screen is the 3.5" TFT
3532 1 - The attached screen is the 7" TFT
3533 2 - The VGA Shield is attached (1024x768)
3537 b - Enable backlight. The TFT backlight pin will be
3541 c - Enable the s3c camera interface.
3542 t - Reserved for enabling touchscreen support. The
3546 https://repo.or.cz/w/linux-2.6/mini2440.git
3551 arch-independent options, each of which is an
3552 aggregation of existing arch-specific options.
3582 ssbd=force-off [ARM64]
3587 This does not have any effect on
3596 have other ways of avoiding SMT-based attacks.
3631 full - Enable mitigation on vulnerable CPUs
3633 full,nosmt - Enable mitigation and disable SMT on
3636 off - Unconditionally disable mitigation
3638 On MDS or TAA affected machines,
3649 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3652 If no <bool> value is specified or if the value
3654 probe on this module. Otherwise, enable/disable
3655 asynchronous probe on this module as indicated by the
3679 module_blacklist= [KNL] Do not load a comma-separated list of
3699 specified value but may be more. If movablecore on its
3704 movable_node [KNL,EARLY] Boot-time switch to make hotplugable memory
3711 Format: <name>,<region-number>,<size>,<offset>
3714 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3753 something different and driver-specific.
3782 [NFS] set the TCP port on which the NFSv4 callback
3793 [NFS] enable 64-bit inode numbers.
3794 If zero, the NFS client will fake up a 32-bit inode
3796 of returning the full 64-bit number.
3797 The default is to return 64-bit inode numbers.
3832 [NFS4] Specify an additional fixed unique ident-
3839 to a lease timeout on the server. Please note that
3841 no guarantees that the file will remain unchanged
3852 If zero, no implementation identification information
3863 driver. A non-zero value sets the minimum interval
3868 server-to-server copies for which this server is
3880 server-to-server copy, knfsd temporarily mounts
3887 See Documentation/admin-guide/nfs/nfsroot.rst.
3889 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3890 See Documentation/admin-guide/nfs/nfsroot.rst.
3893 See Documentation/admin-guide/nfs/nfsroot.rst.
3897 NMI stack-backtrace request.
3906 0 - turn hardlockup detector in nmi_watchdog off
3907 1 - turn hardlockup detector in nmi_watchdog on
3908 rNNN - configure the watchdog with raw perf event 0xNNN
3911 timeout occurs (or 'nopanic' to not panic on an NMI
3921 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3925 no4lvl [RISCV,EARLY] Disable 4-level and 5-level paging modes.
3926 Forces kernel to use 3-level paging instead.
3928 no5lvl [X86-64,RISCV,EARLY] Disable 5-level paging mode. Forces
3929 kernel to use 4-level paging instead.
3953 turn on/off it dynamically.
3962 no_entry_flush [PPC,EARLY] Don't flush the L1-D cache when entering the kernel.
3964 noexec32 [X86-64]
3965 This affects only 32-bit executables.
3966 noexec32=on: enable non-executable mappings (default)
3968 noexec32=off: disable non-executable mappings
3979 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3981 legacy floating-point registers on task switch.
3991 difficult since unequal pointers can no longer be
3992 compared. However, if this command-line option is
3995 debugging the kernel. Please do not use on production
4003 to be effective. This is useful on platforms where the
4014 Valid arguments: on, off
4015 Default: on
4033 nointremap [X86-64,Intel-IOMMU,EARLY] Do not enable interrupt
4035 [Deprecated - use intremap=off]
4041 noirqdebug [X86-32] Disables the code which attempts to detect and
4051 no-kvmapf [X86,KVM,EARLY] Disable paravirtualized asynchronous page
4054 no-kvmclock [X86,KVM,EARLY] Disable paravirtualized KVM clock driver
4056 nolapic [X86-32,APIC,EARLY] Do not enable or use the local APIC.
4058 nolapic_timer [X86-32,APIC,EARLY] Do not use the local APIC timer.
4060 nomce [X86-32] Disable Machine Check Exception
4062 nomfgpt [X86-32] Disable Multi-Function General Purpose
4068 not load if they could possibly displace the pre-
4071 perform display-mode changes or accelerated rendering.
4084 nopcid [X86-64,EARLY] Disable the PCID cpu feature.
4089 nopti [X86-64,EARLY]
4094 as generic guest with no PV drivers. Currently support
4099 which allow the hypervisor to 'idle' the guest on lock
4105 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
4111 no-scroll [VGA] Disables scrollback.
4112 This is required for the Braillex ib80-piezo Braille
4115 nosgx [X86-64,SGX,EARLY] Disables Intel SGX kernel support.
4135 nosoftlockup [KNL] Disable the soft-lockup detector.
4141 nospectre_bhb [ARM64,EARLY] Disable all mitigations for Spectre-BHB (branch
4154 no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,LOONGARCH,EARLY]
4164 [PPC,EARLY] Don't flush the L1-D cache after accessing user data.
4173 data will be no longer available. This parameter
4177 no-vmw-sched-clock
4182 soft-lockup and NMI watchdog (hard-lockup).
4186 nox2apic [X86-64,APIC,EARLY] Do not enable x2APIC mode.
4188 NOTE: this parameter will be ignored on systems with the
4194 enabling legacy floating-point and sse state.
4201 xsaveopt supports it on xsaveopt enabled systems.
4209 memory on xsaves enabled systems.
4216 n. So during boot up some boot time memory for per-cpu
4217 variables need be pre-allocated for later physical cpu
4248 See Documentation/admin-guide/sysctl/vm.rst for details.
4251 See Documentation/core-api/debugging-via-ohci1394.rst for more
4266 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
4270 boundary - index of last SLC block on Flex-OneNAND.
4272 lock - Configure if Flex-OneNAND boundary should be locked.
4277 Always panic on oopses. Default is to just kill the
4280 This will also cause panics on machine check exceptions.
4291 page_owner= [KNL,EARLY] Boot-time page_owner enabling option.
4294 we can turn it on.
4295 on: enable the feature
4297 page_poison= [KNL,EARLY] Boot-time parameter changing the state of
4298 poisoning on the buddy allocator, available with
4301 on: turn on poisoning
4309 panic= [KNL] Kernel behaviour on panic: delay <timeout>
4324 bitmask set on panic_on_taint.
4325 See Documentation/admin-guide/tainted-kernels.rst for
4326 extra details on the taint flags that users can pick
4330 on a WARN().
4337 bit 3: print locks info if CONFIG_LOCKDEP is on
4362 settings on that particular port), or 'nofifo'
4365 are specified on the command line, starting
4370 a specific mode. This is necessary on Pegasos
4371 computer where firmware has no options for setting
4378 Set to non-zero to probe primary and secondary ISA
4379 port ranges on PCI systems where no PCI PATA device
4384 Set to non-zero if a chip is present that snoops speed
4389 Set to 1, 2, or 3 for HT 6560A on the primary channel,
4395 Set to 1, 2, or 3 for HT 6560B on the primary channel,
4404 the second channel, and so on. The sequence will often
4406 legacy channel, and so on, but the handling of a PCI
4413 Set to 1, 2, or 3 for Opti 82c611A on the primary
4419 Set to 1, 2, or 3 for Opti 82c465MV on the primary
4427 Bit 0 is for mode 0, bit 1 is for mode 1, and so on.
4432 Set to non-zero to probe tertiary and further ISA
4433 port ranges on PCI systems. Disabled by default.
4437 Probe mask for legacy ISA PATA ports. Depending on
4443 the first port in the list above (0x1f0), and so on.
4448 Set to non-zero to probe QDI controllers. By default
4453 Set to non-zero to probe Winbond controllers. Use
4463 mode 0, bit 1 is for mode 1, and so on. Mode 0 only
4475 Some options herein operate on a specific device
4500 bios [X86-32] force use of PCI BIOS, don't access
4502 has a non-standard PCI host bridge.
4503 nobios [X86-32] disallow use of PCI BIOS, only direct
4509 data in IO port 0xCFC, both 32-bit).
4511 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
4512 the function, IO port 0xCFA, also 8-bit, sets
4514 through ports 0xC000-0xCFFF).
4516 on the configuration access mechanisms.
4521 root domains (aka PCI segments, in ACPI-speak).
4526 config space on AMD family 10h CPU
4529 disable the use of MSI interrupts system-wide.
4534 primary IO-APIC for bridges that cannot disable
4541 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
4543 on several machines and they hang the machine
4544 when used, but on other computers it's the only
4547 IRQs or discover secondary PCI buses on your
4565 F0000h-100000h range.
4570 assign-busses [X86] Always assign all PCI bus
4574 in the BIOS $PIR table. This is needed on
4577 notebooks. This will have no effect if ACPI
4582 from ACPI. On BIOSes from 2008 or later, this
4591 <linux-pci@vger.kernel.org>.
4593 bridge windows. This is the default on modern
4595 a bug to <linux-pci@vger.kernel.org>.
4603 This might help on some broken boards which
4607 bfsort Sort PCI devices into breadth-first order.
4610 nobfsort Don't sort PCI devices into breadth-first order.
4612 tuning and use the BIOS-configured MPS defaults.
4616 based on its parent bus. Also set MRRS (Max
4618 value (no larger than the MPS that the device
4622 configuration allows peer-to-peer DMA between
4625 that hot-added devices will work.
4640 A PCI-PCI bridge can be specified if resource
4646 for 4096-byte alignment.
4648 end-to-end CRC checking). Only effective if
4654 on: Turn ECRC on.
4676 on: Turn realloc on
4677 realloc same as realloc=on
4679 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4685 root complex on AMD CPUs. Some GFX hardware
4706 unchanged based on what is specified in
4710 bit-0 : ACS Source Validation
4711 bit-1 : ACS Translation Blocking
4712 bit-2 : ACS P2P Request Redirect
4713 bit-3 : ACS P2P Completion Redirect
4714 bit-4 : ACS Upstream Forwarding
4715 bit-5 : ACS P2P Egress Control
4716 bit-6 : ACS Direct Translated P2P
4726 Validation unchanged from whatever power-up
4740 force Enable ASPM even on devices that claim not to support it.
4741 WARNING: Forcing ASPM on may cause system lockups.
4748 dpc-native Use native PCIe service for DPC only. May
4765 The specified value must be no greater than HPAGE_PMD_ORDER
4770 Keep all power-domains already enabled by bootloader on,
4771 even if no driver has claimed them. This is useful
4773 needed on a platform with proper driver support.
4784 See comments in mm/percpu.c for details on each
4788 pirq= [SMP,APIC] Manual mp-table setup
4789 See Documentation/arch/x86/i386/IO-APIC.rst.
4793 See also Documentation/admin-guide/parport.rst.
4800 This option takes over the PMU facility, so it is no
4804 that number, otherwise (e.g., 'pmu_override=on'), MMCR1
4811 Enable PNP debug messages (depends on the
4812 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4814 current resource usage; turning this on also shows
4821 { on | off | curr | res | no-curr | no-res }
4851 function to NULL. On Idle the CPU just reduces
4866 none - Limited to cond_resched() calls
4867 voluntary - Limited to cond_resched() and might_sleep() calls
4868 full - Any section that isn't explicitly preempt disabled
4873 print-fatal-signals=
4879 coredump - etc.
4882 you might want to try "ulimit -i unlimited".
4893 Disable console loglevel raise on oops, panic
4894 or lockdep-detected issues (only if lock debug is on).
4895 With an exception to setups with low baudrate on
4902 Allows storing messages from non-panic CPUs into
4904 flushed to consoles by the panic-CPU on
4905 a best-effort basis.
4909 printk.devkmsg={on,off,ratelimit}
4911 on - unlimited logging to /dev/kmsg from userspace
4912 off - logging to /dev/kmsg disabled
4913 ratelimit - ratelimit the logging
4924 - 'always': traditional behavior always allows mem overrides.
4925 - 'ptrace': only allow mem overrides for active ptracers.
4926 - 'never': never allow mem overrides.
4930 Limit processor to maximum C-state
4934 Ignore the _CST method to determine C-states,
4941 Param: "schedule" - profile schedule points.
4942 Param: "kvm" - profile VM exits.
4943 Param: <number> - step/bucket size as a power of 2 for
4974 pti= [X86-64] Control Page Table Isolation of user and
4979 on - unconditionally enable
4980 off - unconditionally disable
4981 auto - kernel detects whether your CPU model is
4987 [KNL] Number of legacy pty's. Overwrites compiled-in
4994 radix_hcall_invalidate=on [PPC/PSERIES]
4999 See Documentation/admin-guide/md.rst.
5002 See Documentation/admin-guide/blockdev/ramdisk.rst.
5020 that depend on stack address determinism or
5021 cross-syscall address exposures. This is only
5022 available on architectures that have defined
5027 ras=option[,option,...] [KNL] RAS-specific options
5033 rcu_nocbs[=cpu-list]
5038 enable the no-callback CPU mode, which prevents
5043 "p" for RCU-preempt, "s" for RCU-sched, and "g"
5045 "N" is the CPU number. This reduces OS jitter on
5047 and real-time workloads. It can also improve
5051 list of CPUs is set to no-callback mode from boot.
5054 arguments are omitted, no CPU will be set to
5055 no-callback mode from boot but the mode may be
5065 make these kthreads poll for callbacks.
5066 This improves the real-time response for the
5077 Do only a one-line RCU CPU stall warning when
5078 there is an ongoing too-long CSD-lock wait.
5083 hammer on the sysfs variable if they so choose.
5084 If triggered before the RCU grace-period machinery
5094 RCU grace-period cleanup.
5098 RCU grace-period initialization.
5102 RCU grace-period pre-initialization, that is,
5103 the propagation of recent CPU-hotplug changes up
5107 Set delay from grace-period initialization to
5120 soliciting quiescent-state help from
5123 a value based on the most recent settings
5132 Set the SCHED_FIFO priority of the RCU per-CPU
5135 and for the RCU grace-period kthreads (rcu_bh,
5137 set, valid values are 1-99 and the default is 1
5138 (the least-favored priority). Otherwise, when
5139 RCU_BOOST is not set, valid values are 0-99 and
5140 the default is zero (non-realtime operation).
5145 On callback-offloaded (rcu_nocbs) CPUs,
5148 use of the ->nocb_bypass list. However, in the
5149 common non-flooded case, RCU queues directly to
5150 the main ->cblist in order to avoid the extra
5151 overhead of the ->nocb_bypass list and its lock.
5153 a single jiffy, RCU pre-queues the callbacks into
5154 the ->nocb_bypass queue. The definition of "too
5158 On callback-offloaded (rcu_nocbs) CPUs, avoid
5171 batch limiting is re-enabled.
5175 RCU's force-quiescent-state scan will aggressively
5179 on rcutree.qhimark at boot time and to zero to
5183 Set the page-cache refill delay (in milliseconds)
5184 in response to low-memory conditions. The range
5188 Set the shift-right count to use to compute
5189 the callback-invocation batch limit bl from
5190 the number of callbacks queued on this CPU.
5196 Please note that this callback-invocation batch
5197 limit applies only to non-offloaded callback
5206 cache-to-cache transfer latencies.
5212 and for NUMA systems with large remote-access
5228 the wakeup overhead on the global grace-period
5229 kthread, but increases that same overhead on
5230 each group's NOCB grace-period kthread.
5233 Cause the grace-period kthread to get an extra
5235 it should at force-quiescent-state time.
5248 this specifies an rcu_read_unlock()-time delay
5252 of RCU-protected pointers after the relevant
5262 per-CPU rcuc kthreads. Defaults to a non-zero
5291 grace-period primitives such as call_rcu().
5302 grace-period primitives.
5305 Set test-start holdoff period. The purpose of
5323 Test the double-argument variant of kfree_rcu().
5325 rcuscale.kfree_rcu_test_single, both the single-
5326 and double-argument variants are tested.
5329 Test the single-argument variant of kfree_rcu().
5331 rcuscale.kfree_rcu_test_double, both the single-
5332 and double-argument variants are tested.
5346 does not affect the data-collection interval,
5351 Set number of RCU readers. The value -1 selects
5353 "n" less than -1 selects N-n+1, where N is again
5354 the number of CPUs. For example, -2 selects N
5355 (the number of CPUs), -3 selects N+1, and so on.
5356 A value of "n" less than or equal to -N selects
5369 complete. This is useful for hands-off automated
5376 Write-side holdoff between grace periods,
5378 no holdoff.
5381 Additional write-side holdoff between grace
5383 says no holdoff.
5399 for RCU grace-period forward-progress testing
5406 Specify the fraction of a CPU-stall-warning
5407 period to do tight-loop forward-progress testing.
5411 forward-progress tests.
5415 need_resched() during tight-loop forward-progress
5419 Use conditional/asynchronous update-side
5423 Use expedited update-side primitives, if available.
5426 Use normal (non-expedited) asynchronous
5427 update-side primitives, if available.
5430 Use normal (non-expedited) synchronous
5431 update-side primitives, if available. If all
5435 they are all non-zero.
5443 Leak an RCU-protected pointer out of the reader.
5458 Set number of RCU callback-offload togglers.
5463 callback-offload toggling attempts.
5466 Set number of RCU readers. The value -1 selects
5467 N-1, where N is the number of CPUs. A value
5468 "n" less than -1 selects N-n-2, where N is again
5469 the number of CPUs. For example, -2 selects N
5470 (the number of CPUs), -3 selects N+1, and so on.
5473 Enable debug-object double-call_rcu() testing.
5476 Set time (s) after boot for CPU-hotplug testing.
5479 Set time (jiffies) between CPU-hotplug operations,
5480 or zero to disable CPU-hotplug testing.
5483 Set the number of read-then-exit kthreads used
5485 task-exit processing.
5488 The number of times in a given read-then-exit
5489 episode that a set of read-then-exit kthreads
5494 read-then-exit testing episodes.
5497 Set task-shuffle interval (s). Shuffling tasks
5498 allows some CPUs to go into dyntick-idle mode
5503 is useful for hands-off automated testing.
5512 any other stall-related activity. Note that
5518 in scheduling-while-atomic splats.
5528 on the first stall in the set.
5537 grace-period kthread to test RCU CPU stall
5548 wait for five seconds, and so on. This tests RCU's
5552 Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
5563 Test RCU's dyntick-idle handling. See also the
5604 before the init task is spawned.
5622 Provide statistics on the cputime and count of
5633 Use expedited grace-period primitives, for
5637 real-time latency, and degrade energy efficiency.
5638 No effect on CONFIG_TINY_RCU kernels.
5641 Use only normal grace-period primitives,
5644 real-time latency, CPU utilization, and
5646 increased grace-period latency. This parameter
5647 overrides rcupdate.rcu_expedited. No effect on
5653 only normal grace-period primitives. No effect
5654 on CONFIG_TINY_RCU kernels.
5659 post-boot attempt at an expedited RCU grace
5660 period to instead use normal non-expedited
5661 grace-period processing.
5669 set to the default value of -1.
5672 Set the minimum number of callback-queuing-time
5673 lock-contention events per jiffy required to
5674 cause the RCU Tasks flavors to switch to per-CPU
5677 the default value of -1.
5682 of -1 allows this to be automatically (and
5690 number avoids disturbing real-time workloads,
5694 Number of callbacks on a given CPU that will
5695 cancel laziness on that CPU. Use -1 to disable
5705 only printed prior to the stall-warning message
5749 Run specified binary instead of /init from the ramdisk,
5753 force - Override the decision by the kernel to hide the
5760 Turn on/off individual RDT features. List is:
5763 E.g. to turn on cmt and turn off mba use:
5781 Set test-start holdoff period. The purpose of
5796 but the default has already reduced the per-pass
5797 noise to a handful of picoseconds on ca. 2020
5801 Set number of readers. The default value of -1
5810 Set the read-side critical-section duration,
5814 Specify the read-protection implementation to test.
5834 that are unused, due no driver claiming them. This may
5836 needed on a platform with proper driver support.
5840 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
5853 line will try to reserve the same physical memory on
5870 reservetop= [X86-32,EARLY]
5887 See Documentation/power/swsusp-and-swap-files.rst
5903 AMD-based UNRET and IBPB mitigations alone do not stop
5905 sibling threads. For that reason, STIBP is used on pro-
5906 cessors that support it, and mitigate SMT on processors
5909 off - no mitigation
5910 auto - automatically select a migitation
5911 auto,nosmt - automatically select a mitigation,
5913 the full mitigation (only on Zen1
5915 ibpb - On AMD, mitigate short speculation
5916 windows on basic block boundaries too.
5919 on Intel.
5920 ibpb,nosmt - Like "ibpb" above but will disable SMT
5924 unret - Force enable untrained return thunks,
5925 only effective on AMD f15h-f17h based
5927 unret,nosmt - Like unret, but will disable SMT when STIBP
5949 [KNL] Disable ring 3 MONITOR/MWAIT feature on supported
5955 "riscv,isa" property on devicetree systems when the
5959 ro [KNL] Mount root device read-only on boot
5962 on Mark read-only kernel memory as read-only (default).
5963 off Leave read-only kernel memory writable for debugging.
5964 full Mark read-only kernel memory and aliases as read-only
5969 Enable the uart passthrough on the designated usb port
5970 on Rockchip SoCs. When active, the signals of the
5971 debug-uart get routed to the D+ and D- pins of the usb
5977 block/early-lookup.c for details.
5979 ramdisk, "nfs" and "cifs" for root on a network file
6002 rw [KNL] Mount root device read-write on boot
6004 S [KNL] Run init in single mode
6022 and so on. As a special case a factor of 0 imposes no
6031 solution to mutex-based priority inversion.
6054 and so on.
6061 to 10 seconds for built-in smp_call_function()
6068 that requesting even small non-zero numbers of
6070 softlockup complaints, and so on.
6075 The default of -1 specifies a number of kthreads
6080 test before initiating CPU-hotplug operations.
6084 CPU-hotplug operations. Specifying zero (which
6085 is the default) disables CPU-hotplug operations.
6091 Non-zero values are useful for automated tests.
6114 "wait" parameter. A value of -1 selects the
6115 default if all other weights are -1. However,
6117 value of -1 will instead select a weight of zero.
6122 non-zero "wait" parameter. See weight_single.
6130 on the system.
6135 non-zero "wait" parameter. See weight_single
6147 non-zero "wait" parameter. See weight_single
6151 xtime_lock contention on larger systems, and/or RCU lock
6152 contention on all systems with CONFIG_MAXSMP set.
6154 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
6155 1 -- enable.
6166 0 -- disable.
6167 1 -- enable.
6170 serialnumber [BUGS=X86-32]
6172 sev=option[,option...] [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
6180 to set it to "all" by meaning -- no limit here.
6232 unchanged). Debug options disable merging on their
6251 using the csdlock_debug- kernel parameter.
6256 system. By default, let CSD-lock acquisition
6258 for this value provides a 5-minute timeout.
6260 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
6261 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
6262 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
6263 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
6264 smsc-ircc2.ircc_irq= [HW] IRQ line
6265 smsc-ircc2.ircc_dma= [HW] DMA channel
6266 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
6272 (logical CPUs) to use per physical CPU on systems
6276 Default: -1 (no limit)
6279 [KNL] Should the soft-lockup detector generate panics.
6282 A value of 1 instructs the soft-lockup detector
6283 to panic the machine when a soft-lockup occurs. It is
6286 respective build-time switch to that functionality.
6289 [KNL] Should the soft-lockup detector generate
6290 backtraces on all cpus.
6294 See Documentation/admin-guide/laptops/sonypi.rst
6301 on - (default) Enable the HW or SW mitigation as
6304 vmexit - On systems which don't have the HW mitigation
6305 available, enable the SW mitigation on vmexit
6306 ONLY. On such systems, the host kernel is
6307 protected from VM-originated BHI attacks, but
6309 off - Disable the mitigation.
6316 on - unconditionally enable, implies
6317 spectre_v2_user=on
6318 off - unconditionally disable, implies
6320 auto - kernel detects whether your CPU model is
6323 Selecting 'on' will, and 'auto' may, choose a
6329 Selecting 'on' will also enable the mitigation
6339 retpoline - replace indirect branches
6340 retpoline,generic - Retpolines
6341 retpoline,lfence - LFENCE; indirect branch
6342 retpoline,amd - alias for retpoline,lfence
6343 eibrs - Enhanced/Auto IBRS
6344 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
6345 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
6346 ibrs - use IBRS to protect kernel
6356 on - Unconditionally enable mitigations. Is
6357 enforced by spectre_v2=on
6359 off - Unconditionally disable mitigations. Is
6362 prctl - Indirect branch speculation is enabled,
6365 is inherited on fork.
6368 - Like "prctl" above, but only STIBP is
6374 - Same as "prctl" above, but all seccomp
6379 - Like "seccomp" above, but only STIBP is
6384 auto - Kernel selects the mitigation depending on
6393 [X86,EARLY] Control RAS overflow mitigation on AMD Zen CPUs
6395 off - Disable mitigation
6396 microcode - Enable microcode mitigation only
6397 safe-ret - Enable sw-only safe RET mitigation (default)
6398 ibpb - Enable mitigation by issuing IBPB on
6400 ibpb-vmexit - Issue IBPB only on VMEXIT
6401 (cloud-specific mitigation)
6424 On x86 the options are:
6426 on - Unconditionally disable Speculative Store Bypass
6427 off - Unconditionally enable Speculative Store Bypass
6428 auto - Kernel detects whether the CPU model contains an
6434 prctl - Control Speculative Store Bypass per thread
6437 is inherited on fork.
6438 seccomp - Same as "prctl" above, but all seccomp threads
6444 On powerpc the options are:
6446 on,auto - On Power8 and Power9 insert a store-forwarding
6447 barrier on kernel entry and exit. On Power7
6448 perform a software flush on kernel entry and
6450 off - No action.
6464 off - not enabled
6466 warn - the kernel will emit rate-limited warnings
6469 the default on CPUs that support split lock
6474 fatal - the kernel will send SIGBUS to applications
6479 ratelimit:N -
6499 Certain CPUs are vulnerable to an MDS-like
6519 This kernel-boot parameter defaults to 128,
6520 but takes effect only when the low-order four
6536 on the actual runtime number of CPUs (nr_cpu_ids)
6537 instead of the compile-time CONFIG_NR_CPUS.
6541 grace-period sequence counter wrap for the
6542 srcu_data structure's ->srcu_gp_seq_needed field.
6557 Specifies the number of no-delay instances
6564 Specifies the per-grace-period phase, number of
6565 non-sleeping polls of readers. Beyond this limit,
6571 Specifies number of microseconds of non-sleeping
6572 delay between each non-sleeping poll of readers.
6575 Specifies the number of update-side contention
6580 set for contention-based conversions to occur.
6585 On CPUs that are vulnerable to the Speculative
6590 force-on: Unconditionally enable mitigation for
6592 force-off: Unconditionally disable mitigation for
6603 growing up) the main stack are reserved for no other
6613 Enabled the stack tracer on boot up.
6615 stacktrace_filter=[function-list]
6617 will trace at boot up. function-list is a comma-separated
6625 Set the STI (builtin display/keyboard on the HP-PARISC
6627 as the initial boot-console.
6641 depends on the supported FPU features. This can
6648 faults on kernel addresses.
6653 on kernel addresses.
6671 The default value is 0 (no limit).
6676 service thread pools. Depending on how many NICs
6687 to global on non-NUMA machines)
6692 Sets the upper limit on the number of simultaneous
6706 Format: { on | off | y | n | 1 | 0 }
6708 Execution Facility on pSeries.
6712 <int> -- Number of I/O TLB slabs
6713 <int> -- Second integer after comma. Number of swiotlb
6716 force -- force using of bounce buffers even if they
6718 noforce -- Never use bounce buffers (for debugging)
6723 Set a sysctl parameter, right before loading the init
6733 Ignore sysrq setting - this boot parameter will
6739 Default value is 8192 or 16384 depending on total
6741 cache size. See Documentation/networking/ip-sysctl.rst
6748 Specify "mem" (for Suspend-to-RAM) or "standby" (for
6753 wakeup-capable RTC alarm.
6759 -1: disable all active trip points in all thermal zones
6763 -1: disable all critical trip points in all thermal zones
6770 -1: disable all passive trip points
6776 <deci-seconds>: poll all this frequency
6777 0: no polling (default)
6780 Format: <size>[KMG],<size>[KMG]:<state>;<size>[KMG]-<size>[KMG]:<state>
6785 See Documentation/admin-guide/mm/transhuge.rst for more
6793 Format: {off | on}
6797 e.g. base its process migration decisions on it.
6798 Default is on.
6801 Prevent the CPU-hotplug component of torturing
6802 until after init has spawned.
6805 Dump the ftrace buffer at torture-test shutdown,
6806 even if there were no errors. This can be a
6808 are running concurrently, especially on systems
6809 with rotating-rust storage.
6814 disables verbose-printk() sleeping.
6817 Duration of each verbose-printk() sleep in jiffies.
6833 flush the last written pcr on TPM_SaveState.
6842 https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
6854 tp_printk kernel cmdline option has no effect.
6868 on the console. It may be useful to only include the
6876 [FTRACE] will set tracing buffer size on each cpu.
6880 local - Use the per CPU time stamp counter
6882 depending on the architecture, may not be
6884 global - Event time stamps are synchronize across
6887 counter - Simple counting of events (1, 2, ..)
6891 uptime - Use jiffies as the time stamp.
6892 perf - Use the same clock that perf uses.
6893 mono - Use ktime_get_mono_fast_ns() for time stamps.
6894 mono_raw - Use ktime_get_raw_fast_ns() for time
6896 boot - Use ktime_get_boot_fast_ns() for time stamps.
6900 trace_event=[event-list]
6902 to facilitate early boot debugging. The event-list is a
6903 comma-separated list of trace events to enable. See
6906 trace_instance=[instance-info]
6931 traceoff - Have the tracing instance tracing disabled after it is created.
6932 traceprintk - Have trace_printk() write into this trace instance
6971 trace_options=[option-list]
6973 The option-list is a comma delimited list of options
6987 trace_trigger=[trigger-list]
6988 [FTRACE] Add a event trigger on specific events.
6989 Set a trigger on top of a specific event, with an optional
6999 The above will enable the "stacktrace" trigger on the "sched_switch"
7024 See Documentation/admin-guide/mm/transhuge.rst
7032 - "tpm"
7033 - "tee"
7034 - "caam"
7035 - "dcp"
7045 - "kernel"
7046 - the same value as trusted.source: "tpm" or "tee"
7047 - "default"
7064 Attacks on AMD CPUs. Search the following in your
7070 off - disable the mitigation
7071 on - enable the mitigation (default)
7072 user - mitigate only user/kernel transitions
7073 vm - mitigate only guest/host transitions
7081 high-resolution timer mode on older hardware, and in
7084 Used to run time disable IRQ_TIME_ACCOUNTING on any
7095 (HPET or PM timer) on systems whose TSC frequency was
7100 only on systems where TSC has been deemed trustworthy.
7107 procedure is not reliable, such as on overclocked systems
7117 on - Enable TSX on the system. Although there are
7120 several previous speculation-related CVEs, and
7124 off - Disable TSX on the system. (Note that this
7125 option takes effect only on newer CPUs which are
7132 auto - Disable TSX if X86_BUG_TAA is present,
7133 otherwise enable TSX on the system.
7137 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7143 Similar to Micro-architectural Data Sampling (MDS)
7158 full - Enable TAA mitigation on vulnerable CPUs
7161 full,nosmt - Enable TAA mitigation and disable SMT on
7164 vulnerable to cross-thread TAA attacks.
7165 off - Unconditionally disable TAA mitigation
7167 On MDS-affected machines, tsx_async_abort=off can be
7173 tsx_async_abort=full. On CPUs which are MDS affected
7179 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7185 See also Documentation/input/devices/joystick-parport.rst
7187 udbg-immortal [PPC] When debugging early kernel crashes that
7190 help "seeing" what's going on.
7193 Set number of hash buckets for UDP/UDP-Lite connections
7195 uhci-hcd.ignore_oc=
7197 Some badly-designed motherboards generate lots of
7204 [X86] Cause panic on unknown NMI.
7206 unwind_debug [X86-64,EARLY]
7214 (default -1 = authorized (same as 1),
7220 for newly-detected USB devices (default 2). This
7233 [USB] Set to cycle leds on hubs (default 0 = off).
7248 [USB] Specifies timeout for the initial 64-byte
7255 [USB] A list of quirk entries to augment the built-in
7258 VendorID:ProductID:Flags. The IDs are 4-digit hex
7260 will change the built-in quirk; setting it if it is
7265 a 255-byte read);
7269 Set-Interface requests);
7288 (bInterval-1).
7326 usb-storage.delay_use=
7333 usb-storage.quirks=
7335 override the built-in unusual_devs list. List
7338 and Product ID values (4-digit hex numbers) and
7340 to a common usb-storage quirk flag as follows:
7342 of sense data, not on uas);
7344 bytes of sense data, not on uas);
7348 READ_DISC_INFO command, not on uas);
7364 unlock ejectable media, not on uas);
7367 not on uas);
7369 initial READ(10) command, not on uas);
7371 reported by the device, not on uas);
7372 p = WRITE_CACHE (the device cache is ON
7373 by default, not on uas);
7375 bogus residue values, not on uas);
7382 medium is write-protected).
7384 even if the device claims no cache,
7385 not on uas)
7391 1 - undefined instruction events
7392 2 - system calls
7393 4 - invalid data aborts
7394 8 - SIGSEGV faults
7395 16 - SIGBUS faults
7406 On X86_32, this is an alias for vdso32=. Otherwise:
7411 vdso32= [X86] Control the 32-bit vDSO
7412 vdso32=1: enable 32-bit VDSO
7413 vdso32=0 or vdso32=2: disable 32-bit VDSO
7423 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
7430 If set to 1, on receiving an ACPI notify event
7454 vga= [BOOT,X86-32] Select a particular video mode
7456 Documentation/admin-guide/svga.rst.
7463 enabled on systems with a large amount of memory.
7470 P Enable page structure init time poisoning
7471 - Disable all of the above options
7475 the minimum size (128MB on x86, arm32 platforms).
7478 not exist on many other platforms (including arm64, alpha,
7497 hypervisor to a guest via speculative side-channels.
7499 off - disable the mitigation
7500 ibpb - use Indirect Branch Prediction Barrier
7502 force - force vulnerability detection even on
7505 vsyscall= [X86-64,EARLY]
7508 code). Most statically-linked binaries and older
7527 Default: 0x07 = light gray on black.
7532 see VGA-softcursor.txt. Default: 2 = underline.
7537 This is a 16-member array composed of values
7538 ranging from 0-255.
7543 This is a 16-member array composed of values
7544 ranging from 0-255.
7549 This is a 16-member array composed of values
7550 ranging from 0-255.
7555 Set system-wide default UTF-8 mode for all tty's.
7556 Default is 1, i.e. UTF-8 mode is enabled for all
7561 Format=<-1|0|1>
7562 Set system-wide default for whether a cursor
7563 is shown on new VTs. Default is -1,
7568 vt.italic= [VT] Default color for italic text; 0-15.
7571 vt.underline= [VT] Default color for underlined text; 0-15.
7574 watchdog timers [HW,WDT] For information on watchdog timers,
7575 see Documentation/watchdog/watchdog-parameters.rst
7576 or other driver-specific files in the
7590 Format: <cpu-list>
7608 The default is 0, which disables the panic on stall.
7611 Per-cpu work items which run for longer than this
7614 them from noticeably delaying other per-cpu work
7632 Per-cpu workqueues are generally preferred because
7634 locality; unfortunately, per-cpu workqueues tend to
7637 Enabling this makes the per-cpu workqueues which
7651 Documentation/core-api/workqueue.rst.
7661 on the local CPU. This guarantee is no longer true
7663 may be put on foreign CPUs. This debug option
7664 forces round-robin CPU selection to flush out
7665 usages which depend on the now broken guarantee.
7672 on - Enable writecombine, use WUC for ioremap_wc()
7673 off - Disable writecombine, use SUC for ioremap_wc()
7675 x2apic_phys [X86-64,APIC,EARLY] Use x2apic physical mode instead of
7676 default x2apic cluster mode on platforms
7679 xen_512gb_limit [KNL,X86-64,XEN]
7689 ide-disks -- unplug primary master IDE devices
7690 aux-ide-disks -- unplug non-primary-master IDE devices
7691 nics -- unplug network devices
7692 all -- unplug all emulated devices (NICs and IDE disks)
7693 unnecessary -- unplugging emulated devices is
7696 never -- do not unplug even if version check succeeds
7710 Select whether to always use non-faulting (safe) MSR
7716 run as generic HVM guest with no PV drivers.
7730 xen_timer_slop= [X86-64,XEN,EARLY]
7755 preferred over the 2-level event handling, as it is
7757 much higher. Default is on (use fifo events).
7764 By default on POWER9 and above, the kernel will
7769 controller on both pseries and powernv
7770 platforms. Only useful on POWER9 and above.
7772 xive.store-eoi=off [PPC]
7773 By default on POWER10 and above, the kernel will use
7776 loads instead, as on POWER9.
7778 xhci-hcd.quirks [USB,KNL]
7784 Format: { early | on | rw | ro | off }
7787 early Call xmon as early as possible on boot; xmon
7789 on xmon debugger hooks will be installed so xmon
7790 is only called on a kernel crash. Default mode,
7794 is called only on a kernel crash, mode is write,