Lines Matching +full:disable +full:- +full:port +full:- +full:power +full:- +full:control
2 Advanced Configuration and Power Interface
5 force -- enable ACPI if default was off
6 on -- enable ACPI but allow fallback to DT [arm64,riscv64]
7 off -- disable ACPI if default was on
8 noirq -- do not use ACPI for IRQ routing
9 strict -- Be less tolerant of platforms that are not
11 rsdt -- prefer RSDT over (default) XSDT
12 copy_dsdt -- copy DSDT to memory
16 See also Documentation/power/runtime_pm.rst, pci=noacpi
26 If set to vendor, prefer vendor-specific driver
31 If set to none, disable the ACPI backlight interface.
40 Disable AML predefined validation mechanism
58 Documentation/firmware-guide/acpi/debug.rst for more information about
116 Format: <byte> or <bitmap-list>
119 Disable auto-serialization of AML methods
120 AML control methods that contain the opcodes to create
122 auto-serialization feature.
126 acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump
130 Disable installation of static SSDTs at early boot time
140 Ignore the ACPI-based watchdog interface (WDAT) and let
141 a native driver control the watchdog device instead.
161 acpi_osi=! # disable all built-in OS vendor
163 acpi_osi=!! # enable all built-in OS vendor
165 acpi_osi= # disable all strings
200 is useful when one want to control the state of the
220 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
225 For broken nForce2 BIOS resulting in XT-PIC timer.
231 See Documentation/power/video.rst for information on
234 as soon as the kernel's real-mode entry point is called.
246 control method, with respect to putting devices into
247 low power states, to be enforced (the ACPI 2.0 ordering
267 off: disable AGP support
272 See Documentation/sound/alsa-configuration.rst
279 align_va_addr= [X86-64]
284 CPU-intensive style benchmark, and it can vary highly in
287 32: only for 32-bit processes
288 64: only for 64-bit processes
289 on: enable for both 32- and 64-bit processes
290 off: disable for both 32- and 64-bit processes
300 Allow execve() of 32-bit applications and setting of the
302 subset of the CPUs support 32-bit EL0. When this
303 parameter is present, the set of CPUs supporting 32-bit
305 and hot-unplug operations may be restricted.
307 See Documentation/arch/arm64/asymmetric-32bit.rst for more
310 amd_iommu= [HW,X86-64]
313 fullflush - Deprecated, equivalent to iommu.strict=1
314 off - do not initialize any AMD IOMMU found in
316 force_isolation - Force device isolation for all
321 force_enable - Force enable the IOMMU on platforms known
324 pgtbl_v1 - Use v1 page table for DMA-API (Default).
325 pgtbl_v2 - Use v2 page table for DMA-API.
326 irtcachedis - Disable Interrupt Remapping Table (IRT) caching.
328 amd_iommu_dump= [HW,X86-64]
334 amd_iommu_intr= [HW,X86-64]
337 legacy - Use legacy interrupt remapping mode.
338 vapic - Use virtual APIC mode, which allows IOMMU
340 This mode requires kvm-amd.avic=1.
344 disable
357 to the CPPC firmware. then CPPC power algorithm will
377 Power management functions (SPARCstation-4/5 + deriv.)
379 Disable APC CPU standby support. SPARCstation-Fox does
380 not play well with APC CPU idle - disable it if you have
387 when initialising the APIC and IO-APIC components.
388 For X86-32, this can also be used to specify an APIC
405 apm= [APM] Advanced Power Management
408 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
411 0 -- disable.
412 1 -- enable.
415 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
418 arm64.nobti [ARM64] Unconditionally disable Branch Target
421 arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory
424 arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension
427 arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication
430 arm64.nosme [ARM64] Unconditionally disable Scalable Matrix
433 arm64.nosve [ARM64] Unconditionally disable Scalable Vector
457 audit= [KNL] Enable the audit sub-system
459 0 | off - kernel audit is disabled and can not be
461 unset - kernel audit is initialized but disabled and
463 1 | on - kernel audit is initialized and partially
474 behavior is to disable the BAU (i.e. bau=0).
476 0 - Disable the BAU.
477 1 - Enable the BAU.
478 unset - Disable the BAU.
483 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
488 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
493 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
498 Disable BERT OS support on buggy BIOSes.
501 Disable BGRT to avoid flickering OEM logo.
505 See Documentation/block/cmdline-partition.rst
518 See Documentation/admin-guide/bootconfig.rst
523 bttv.pll= See Documentation/admin-guide/media/bttv.rst
532 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
551 inclusive. See arch/mips/include/asm/pgtable-bits.h
558 cgroup_disable= [KNL] Disable a particular controller or optional feature
559 Format: {name of the controller(s) or feature(s) to disable}
561 - foo isn't auto-mounted if you mount all cgroups in
563 - foo isn't visible as an individually mountable
565 - if foo is an optional feature then the feature is
569 cut the overhead, others just disable the usage. So
571 Specifying "pressure" disables per-cgroup pressure
574 cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1
585 nosocket -- Disable socket memory accounting.
586 nokmem -- Disable kernel memory accounting.
587 nobpf -- Disable BPF memory accounting.
592 0 -- check protection applied by kernel (includes
594 1 -- check protection requested by application.
604 Disable CPUID feature X for the kernel. See
606 numbers X. Note the Linux-specific bits are not necessarily
607 stable over kernel options, but the vendor-specific
618 Also note the kernel might malfunction if you disable
627 force such clocks to be always-on nor does it reserve
631 information, see Documentation/driver-api/clk.rst.
633 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
650 [X86-32] pit,hpet,tsc;
657 [X86-64] hpet,tsc
662 Enable/disable the eventstream feature of the ARM
663 architected timer so that code using WFE-based polling
683 clocksource-wdtest.holdoff= [KNL]
689 cma=nn[MG]@[start[MG][-end[MG]]]
700 Sets the size of kernel per-numa memory area for
702 per-numa CMA altogether. And If this option is not
704 With per-numa CMA enabled, DMA users on node nid will
731 com20020= [HW,NET] ARCnet - COM20020 chipset
735 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
739 ARCnet - COM90xx chipset (memory-mapped buffers)
762 Use the specified serial port. The options are of
765 bits, and "f" is flow control ("r" for RTS or
768 See Documentation/admin-guide/serial-console.rst for more
778 Start an early, polled-mode console on the 8250/16550
779 UART at the specified I/O port or MMIO address,
781 MMIO inter-register address stride is either 8-bit
782 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
786 the h/w is not re-initialized.
792 Use to disable console output, i.e., to have kernel
797 If the device connected to the port is not a TTY but a braille
813 syscall, or to executing "dmesg -S --raw" or to reading
828 Enable/disable the CPU sampling based debugging.
829 0: default value, disable debugging
832 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
834 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
837 disable the cpuidle sub-system
843 disable the cpufreq sub-system
851 [X86] Delay for N microsec between assert and de-assert
857 [SMP] Enable/disable parallel bringup of secondary CPUs
863 Run kdump after running panic-notifiers and dumping
876 [KNL, X86-64, ARM64, RISCV] Select a region under 4G first, and
879 See Documentation/admin-guide/kdump/kdump.rst for further details.
884 start-[end] where start and end are both
886 Documentation/admin-guide/kdump/kdump.rst for an example.
889 [KNL, X86-64, ARM64, RISCV] range could be above 4G.
896 [KNL, X86-64, ARM64, RISCV] range under 4G. When crashkernel=X,high
901 low memory is needed to make sure DMA buffers for 32-bit
905 --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
906 --> arm64: 128MiB
907 --> riscv: 128MiB
910 0: to disable low allocation.
915 [KNL] Disable crypto self-tests
923 csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
935 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
936 (one device per port)
937 Format: <port#>,<type>
938 See also Documentation/input/devices/joystick-parport.rst
951 [KNL] verbose locking self-tests
954 self-tests.
956 (no extra messages), setting it to -1 (all bits set)
957 will print _a_lot_ more information - normally only
964 parameter allows control of the order of pages that will
992 Format: { on, no-mount, off }
994 no-mount:
999 get a -EPERM as result when trying to register files
1003 Default value is set in build-time with a kernel configuration.
1015 Documentation/admin-guide/mm/hugetlbpage.rst.
1029 delayacct [KNL] Enable per-task delay accounting
1042 [HW] Report power status in /proc/i8k
1076 disable= [IPV6]
1080 Disable RADIX MMU mode on POWER9
1083 Disable TLBIE instruction. Currently does not work
1091 disable BSP to wake up multiple CPUs without
1096 Disable Dynamic DMA Window support. Use this
1114 Disable PIN 1 of APIC timer
1117 dis_ucode_ldr [X86] Disable the microcode loader.
1124 entries for DMA-API debugging code. One entry is
1125 required per DMA-API allocation. Use this if the
1126 DMA-API debugging code disables itself because the
1130 With this option the DMA-API debugging driver
1150 are enabled. In order to disable RFDS mitigation all
1154 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
1168 Generic built-in EDID data sets are used, if one of
1173 available in Documentation/admin-guide/edid.rst. An EDID
1185 Control how the dt_cpu_ftrs device-tree binding is
1195 what data is available or for reverse-engineering.
1200 Documentation/admin-guide/dynamic-debug-howto.rst
1211 determined by stdout-path property in device tree's
1216 Start an early, polled-mode console on a Cadence
1217 (xuartps) serial port at the specified address. Only
1219 specified, the serial port must already be setup and
1227 Start an early, polled-mode console on the 8250/16550
1228 UART at the specified I/O port or MMIO address.
1229 MMIO inter-register address stride is either 8-bit
1230 (mmio) or 32-bit (mmio32 or mmio32be).
1240 Start an early, polled-mode console on a pl011 serial
1241 port at the specified address. The pl011 serial port
1244 the driver will use only 32-bit accessors to read/write
1248 Start an early console on a litex serial port at the
1249 specified address. The serial port must already be
1253 Start an early, polled-mode console on a meson serial
1254 port at the specified address. The serial port must
1259 Start an early, polled-mode console on an msm serial
1260 port at the specified address. The serial port
1265 Start an early, polled-mode console on an msm serial
1266 dm port at the specified address. The serial port
1271 Start an early, polled-mode console on a serial port
1273 specified address. The serial port must already be
1277 Start an early, polled-mode console on a serial port
1279 specified address. The serial port must already be
1283 Use RISC-V SBI (Supervisor Binary Interface) for early
1296 a correct base address of the selected UART port. The
1297 serial port must already be setup and configured.
1301 Start an early, polled-mode console on a lantiq serial
1302 (lqasc) port at the specified address. The serial port
1311 port must already be setup and configured.
1315 Start an early, polled-mode, output-only console on the
1320 Start an early, polled-mode console on the
1321 Armada 3700 serial port at the specified
1322 address. The serial port must already be setup
1326 Start an early, polled-mode console on a Qualcomm
1327 Generic Interface (GENI) based serial port at the
1328 specified address. The serial port must already be
1334 coherent non-x86 systems that use system memory for
1341 address must be provided, and the serial port must
1359 Append ",keep" to not disable it when the real console
1362 Only one of vga, serial, or usb debug port can
1368 replacing ttySn with an I/O port address, like this:
1370 You can find the port for a given device in
1372 2: uart:ST16650V2 port:00001008 irq:18 ...
1388 edac_report= [HW,EDAC] Control how to report EDAC event
1392 off: disable H/W event reporting through EDAC.
1404 disable_early_pci_dma: disable the busmaster bit on all
1406 nochunk: disable reading files in "chunks" in the EFI
1409 noruntime : disable EFI runtime services support
1413 claim. Specify efi=nosoftreserve to disable this
1434 attribute is added to range 0x100000000-0x180000000 and
1435 0x10a0000000-0x1120000000.
1439 range 0x240000000-0x43fffffff.
1451 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1466 via a serial port see kgdboc_earlycon instead.
1468 elanfreq= [X86-32]
1476 See Documentation/admin-guide/kdump/kdump.rst for details.
1492 0 -- permissive (log only, no denials).
1493 1 -- enforcing (deny and log).
1499 Disable Error Record Serialization Table (ERST)
1525 See also Documentation/fault-injection/.
1529 See Documentation/admin-guide/sysctl/net.rst for
1533 See Documentation/admin-guide/blockdev/floppy.rst.
1536 [IA-64] Avoid check_sal_cache_flush which may hang on
1541 forcepae [X86-32]
1543 Many Pentium M systems disable PAE but may have a
1577 ftrace_filter=[function-list]
1579 tracer at boot up. function-list is a comma-separated
1584 ftrace_notrace=[function-list]
1586 function-list. This list can be changed at run time
1590 ftrace_graph_filter=[function-list]
1593 function-list is a comma-separated list of functions
1597 ftrace_graph_notrace=[function-list]
1599 function-list. This list is a comma-separated list of
1619 off -- Don't create device links from firmware info.
1620 permissive -- Create device links from firmware info
1623 on -- Create device links from firmware info and use it
1625 rpm -- Like "on", but also use to order runtime PM.
1638 strict -- Default. Continue waiting on consumers to
1640 timeout -- Give up waiting on consumers and call
1648 support via parallel port (up to 5 devices per port)
1649 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1650 See also Documentation/input/devices/joystick-parport.rst
1654 gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
1659 [X86,INTEL] Control the Gather Data Sampling (GDS)
1671 force: Disable AVX to mitigate systems without
1676 off: Disable GDS mitigation.
1678 gcov_persist= [GCOV] When non-zero (default), profiling data for
1688 gpio-mockup.gpio_mockup_ranges
1691 gpio-mockup.gpio_mockup_named_lines
1723 against bounds-checking flaws in the kernel's
1726 off Disable hardened usercopy checks.
1729 [KNL] Should the hard-lockup detector generate
1735 for 64-bit NUMA, off otherwise.
1738 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1744 Disable Hardware Error Source Table (HEST) support;
1745 corresponding firmware-first mode error processing
1752 no Disable hibernation and resume.
1755 during restoration read-only).
1762 highres= [KNL] Enable/disable high resolution timer mode.
1781 hpet= [X86-32,HPET] option to control HPET usage
1782 Format: { enable (default) | disable | force |
1784 disable: disable HPET and use PIT instead
1798 number of pages to allocate per-node can be specified.
1799 See also Documentation/admin-guide/mm/hugetlbpage.rst.
1810 Documentation/admin-guide/mm/hugetlbpage.rst.
1821 boot-time allocation of gigantic hugepages is skipped.
1826 Control if HugeTLB Vmemmap Optimization (HVO) is enabled.
1832 off: disable HVO
1849 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1855 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1871 [HW] Enable printing of interrupt data from the KBD port
1872 (disabled by default, and as a pre-condition
1874 i8042.direct [HW] Put keyboard port into non-translated mode
1876 keyboard and cannot control its state
1878 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
1879 i8042.nokbd [HW] Don't check/create keyboard port
1880 i8042.noloop [HW] Disable the AUX Loopback command while probing
1881 for the AUX port
1888 suspend-to-ram transitions, only during s2r
1896 i8042.kbdreset [HW] Reset device connected to KBD port
1912 -1 -- never invert brightness
1913 0 -- machine default
1914 1 -- force brightness inversion
1924 will use a lot of power and make the system run hot.
1928 idle=nomwait: Disable mwait for CPU C-states
1956 legacy only accept legacy-NaN binaries, if supported
1958 2008 only accept 2008-NaN binaries, if supported
1967 'relaxed' straps the emulator for both legacy-NaN and
1968 2008-NaN, whereas 'strict' enables legacy-NaN only on
1977 Ignore loglevel setting - this will print /all/
2044 Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
2045 "ima-sigv2" }
2046 Default: "ima-ng"
2078 initcall_blacklist= [KNL] Do not execute a comma-separated list of
2079 initcall functions. Useful for debugging built-in
2120 int_pln_enable [X86] Enable power limit notification interrupt
2124 0 -- basic integrity auditing messages. (Default)
2125 1 -- additional integrity auditing messages.
2131 Disable intel iommu driver.
2153 could harm performance of some high-throughput
2162 1 to 9 specify maximum depth of C-state.
2165 disable
2171 algorithms for p-state selection. There are two
2172 P-state selection algorithms provided by
2175 on whether or not the hardware managed P-states
2182 used along with the hardware-managed P-states (HWP)
2186 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2187 instead of acpi-cpufreq may disable platform features, such
2188 as thermal controls and power capping, that rely on ACPI
2189 P-States information being indicated to OSPM and therefore
2192 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2194 Do not enable hardware P state control (HWP)
2198 hardware P state control (HWP) if available.
2201 Description Table, specifies preferred power management
2205 Allow per-logical-CPU P-State performance control limits using
2208 intremap= [X86-64, Intel-IOMMU]
2210 off disable Interrupt Remapping
2211 nosid disable Source ID checking
2213 BIOS x2APIC opt-out request will be ignored
2214 nopost disable Interrupt Posting
2216 iomem= Disable strict checking of access to MMIO memory
2233 Disable IOMMU bypass, using IOMMU for PCI devices.
2235 iommu.forcedac= [ARM64, X86] Control IOVA allocation for PCI devices.
2237 0 - Try to allocate a 32-bit DMA address first, before
2239 1 - Allocate directly from the full usable range,
2241 greater than 32-bit addressing.
2245 0 - Lazy mode.
2251 1 - Strict mode.
2254 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2256 legacy driver-specific options takes precedence.
2261 0 - Use IOMMU translation for DMA.
2262 1 - Bypass the IOMMU for DMA.
2263 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2265 io7= [HW] IO7 for Marvel-based Alpha systems
2271 Standard port 0x80 based delay
2273 Alternate port 0xed based delay (needed on some systems)
2280 See Documentation/admin-guide/nfs/nfsroot.rst.
2304 Enables support for pseudo-NMIs in the kernel. This
2323 [Deprecated - use cpusets instead]
2324 Format: [flag-list,]<cpu-list>
2330 Disable the tick when a single task runs.
2347 advised to use cpusets instead to disable scheduler load
2355 "number of CPUs in system - 1".
2381 The format of <cpu-list> is described above.
2385 ivrs_ioapic [HW,X86-64]
2386 Provide an override to the IOAPIC-ID<->DEVICE-ID
2390 For example, to map IOAPIC-ID decimal 10 to
2396 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2399 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2403 ivrs_hpet [HW,X86-64]
2404 Provide an override to the HPET-ID<->DEVICE-ID
2408 For example, to map HPET-ID decimal 10 to
2414 * To map HPET-ID decimal 0 to PCI device 00:14.0
2417 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2421 ivrs_acpihid [HW,X86-64]
2422 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2426 For example, to map UART-HID:UID AMD0020:0 to
2432 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2435 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2456 kernelcore= [KNL,X86,IA-64,PPC]
2459 the kernel for non-movable allocations. The requested
2469 subsystem. Note that allocations like PTEs-from-HighMem
2477 for non-movable allocations and remaining memory is used
2481 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
2484 port as it is probed via PCI. The poll interval is
2486 each poll cycle to the debug port in case you need
2488 gdb or control-c on the dbgp connection. When
2489 not using this parameter you use sysrq-g to break into
2494 or a supported polling keyboard driver (non-usb).
2521 Configure the RouterBoard 532 series on-chip
2524 kmemleak= [KNL] Boot-time kmemleak enable/disable
2530 kprobe_event=[probe-list]
2532 The probe-list is a semicolon delimited list of probe
2543 kpti= [ARM64] Control page table isolation of user
2562 execution by eliminating the write-protection faults
2607 back to huge pages. If the value is a non-zero N, KVM will
2612 kvm-amd.nested= [KVM,AMD] Control nested virtualization feature in
2615 kvm-amd.npt= [KVM,AMD] Control KVM's use of Nested Page Tables,
2616 a.k.a. Two-Dimensional Page Tables. Default is 1
2617 (enabled). Disable by KVM if hardware lacks support
2620 kvm-arm.mode=
2623 none: Forcefully disable KVM.
2625 nvhe: Standard nVHE-based mode, without support for
2628 protected: nVHE-based mode with support for guests whose
2631 nested: VHE-based mode with support for nested
2636 mode to "protected" will disable kexec and hibernation
2640 kvm-arm.vgic_v3_group0_trap=
2641 [KVM,ARM] Trap guest accesses to GICv3 group-0
2644 kvm-arm.vgic_v3_group1_trap=
2645 [KVM,ARM] Trap guest accesses to GICv3 group-1
2648 kvm-arm.vgic_v3_common_trap=
2652 kvm-arm.vgic_v4_enable=
2664 kvm-intel.ept= [KVM,Intel] Control KVM's use of Extended Page Tables,
2665 a.k.a. Two-Dimensional Page Tables. Default is 1
2666 (enabled). Disable by KVM if hardware lacks support
2669 kvm-intel.emulate_invalid_guest_state=
2670 [KVM,Intel] Control whether to emulate invalid guest
2671 state. Ignored if kvm-intel.enable_unrestricted_guest=1,
2677 kvm-intel.flexpriority=
2678 [KVM,Intel] Control KVM's use of FlexPriority feature
2679 (TPR shadow). Default is 1 (enabled). Disable by KVM if
2682 kvm-intel.nested=
2683 [KVM,Intel] Control nested virtualization feature in
2686 kvm-intel.unrestricted_guest=
2687 [KVM,Intel] Control KVM's use of unrestricted guest
2689 is 1 (enabled). Disable by KVM if EPT is disabled or
2692 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2693 CVE-2018-3620.
2704 kvm-intel.vpid= [KVM,Intel] Control KVM's use of Virtual Processor
2706 (enabled). Disable by KVM if hardware lacks support
2710 Control mitigation for L1D based snooping vulnerability.
2724 on - enable the interface for the mitigation
2726 l1tf= [X86] Control mitigation of the L1TF vulnerability on
2738 SMT control and L1D flush control via the
2747 flush runtime control. Implies the
2749 (i.e. sysfs control of SMT is disabled.)
2756 SMT control and L1D flush control via the
2768 SMT control and L1D flush control via the
2789 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2795 lapic [X86-32,APIC] Enable the local APIC even if BIOS
2799 value for LAPIC timer one-shot implementation. Default
2804 in C2 power state.
2806 libata.dma= [LIBATA] DMA control
2807 libata.dma=0 Disable all PATA and SATA DMA
2822 libata.force= [LIBATA] Force configurations. The format is a comma-
2823 separated list of "[ID:]VAL" where ID is PORT[.DEVICE].
2824 PORT and DEVICE are decimal numbers matching port, link
2827 omitted, the last PORT and DEVICE values are used. If
2832 the port and all links and devices behind it. DEVICE
2834 first fan-out link behind PMP device. It does not
2844 Any ID with matching PORT is used.
2848 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2855 * rstonce: only attempt one reset during hot-unplug
2858 * [no]dbdelay: Enable or disable the extra 200ms delay
2864 * [no]ncqtrim: Enable or disable queued DSM TRIM.
2866 * [no]ncqati: Enable or disable NCQ trim on ATI chipset.
2868 * [no]trim: Enable or disable (unqueued) TRIM.
2881 * [no]dmalog: Enable or disable the use of the
2884 * [no]iddevlog: Enable or disable access to the
2887 * [no]logdir: Enable or disable access to the general
2898 * [no]lpm: Enable or disable link power management.
2903 * [no]fua: Disable or enable FUA (Force Unit Access)
2908 * disable: Disable this device.
2918 lockd.nlm_tcpport=N [NFS] Assign TCP port.
2924 lockd.nlm_udpport=M [NFS] Assign UDP port.
2937 Set the number of locking read-acquisition kthreads.
2942 Set the number of locking write-acquisition kthreads.
2945 Set time (s) after boot for CPU-hotplug testing.
2948 Set time (s) between CPU-hotplug operations, or
2949 zero to disable CPU-hotplug testing.
2952 Set task-shuffle interval (jiffies). Shuffling
2953 tasks allows some CPUs to go into dyntick-idle
2958 is useful for hands-off automated testing.
2974 Run the write-side locktorture kthreads at
2975 sched_set_fifo() real-time priority.
2995 7 (KERN_DEBUG) debug-level messages
2998 in bytes. n must be a power of two and greater
3005 logo.nologo [FB] Disables display of the built-in Linux logo.
3011 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
3012 lp=reset first parallel port). 'lp=0' disables the
3018 lp0. A port specification may be 'none' to skip
3021 port specification list means that device IDs
3022 from each port should be examined, to see if
3023 an IEEE 1284-compliant printer is attached; if
3029 time-consuming boot-time autodetection (up to 250 ms per
3050 machvec= [IA-64] Force the use of a particular machine-vector
3056 Example: machtype=lemote-yeeloong-2f-7inch
3058 max_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory greater
3071 (loop.max_loop) unconditionally pre-created at init time. The default
3074 devices can be requested on-demand with the
3075 /dev/loop-control interface.
3077 mce [X86-32] Machine Check Exception
3079 mce=option [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
3082 See Documentation/admin-guide/md.rst.
3089 Control mitigation for the Micro-architectural Data
3104 full - Enable MDS mitigation on vulnerable CPUs
3105 full,nosmt - Enable MDS mitigation and disable
3107 off - Unconditionally disable MDS mitigation
3109 On TAA-affected machines, mds=off can be prevented by
3111 mitigated with the same mechanism so in order to disable
3118 For details see: Documentation/admin-guide/hw-vuln/mds.rst
3132 [ARC,MICROBLAZE] - the limit applies only to low memory,
3135 [ARM64] - only limits memory covered by the linear
3148 [ARM,MIPS] - override the memory layout reported by
3155 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
3162 per-device physically contiguous DMA buffers.
3170 See Documentation/admin-guide/mm/memory-hotplug.rst.
3195 Example: Exclude memory from 0x18690000-0x1869ffff
3209 memmap=<size>%<offset>-<oldtype>+<newtype>
3211 from <oldtype> to <newtype>. If "-<oldtype>" is left
3226 repeatable BIOS-originated corruption always
3262 default : 0 <disable>
3270 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
3278 Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
3282 s2idle - Suspend-To-Idle
3283 shallow - Power-On Suspend or equivalent (if supported)
3284 deep - Suspend-To-RAM or equivalent (if supported)
3285 See Documentation/admin-guide/pm/sleep-states.rst.
3287 mfgpt_irq= [IA-32] Specify the IRQ to use for the
3288 Multi-Function General Purpose Timers on AMD Geode
3291 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
3294 problem by letting the user disable the workaround.
3298 min_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory below this
3305 0 - The attached screen is the 3.5" TFT
3306 1 - The attached screen is the 7" TFT
3307 2 - The VGA Shield is attached (1024x768)
3311 b - Enable backlight. The TFT backlight pin will be
3315 c - Enable the s3c camera interface.
3316 t - Reserved for enabling touchscreen support. The
3318 kernel as of 2.6.30, a preliminary port can be found
3320 https://repo.or.cz/w/linux-2.6/mini2440.git
3323 [X86,PPC,S390,ARM64] Control optional mitigations for
3325 arch-independent options, each of which is an
3326 aggregation of existing arch-specific options.
3329 Disable all optional CPU mitigations. This
3350 ssbd=force-off [ARM64]
3363 have other ways of avoiding SMT-based attacks.
3378 parameter allows control of the logging verbosity for
3385 [X86,INTEL] Control mitigation for the Processor
3398 full - Enable mitigation on vulnerable CPUs
3400 full,nosmt - Enable mitigation and disable SMT on
3403 off - Unconditionally disable mitigation
3409 disable this mitigation, you need to specify
3416 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3421 probe on this module. Otherwise, enable/disable
3427 by default. To enable/disable async probing for a
3428 specific module, use the module specific control that
3446 module_blacklist= [KNL] Do not load a comma-separated list of
3460 movablecore= [KNL,X86,IA-64,PPC]
3471 movable_node [KNL] Boot-time switch to make hotplugable memory
3478 Format: <name>,<region-number>,<size>,<offset>
3481 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3487 ARM/S3C2412 JIVE boot control
3489 See arch/arm/mach-s3c/mach-jive.c
3525 something different and driver-specific.
3536 0 to disable accounting
3554 [NFS] set the TCP port on which the NFSv4 callback
3558 [NFS] enable 64-bit inode numbers.
3559 If zero, the NFS client will fake up a 32-bit inode
3561 of returning the full 64-bit number.
3562 The default is to return 64-bit inode numbers.
3597 [NFS4] Specify an additional fixed unique ident-
3628 driver. A non-zero value sets the minimum interval
3633 server-to-server copies for which this server is
3645 server-to-server copy, knfsd temporarily mounts
3652 See Documentation/admin-guide/nfs/nfsroot.rst.
3654 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3655 See Documentation/admin-guide/nfs/nfsroot.rst.
3658 See Documentation/admin-guide/nfs/nfsroot.rst.
3662 NMI stack-backtrace request.
3671 0 - turn hardlockup detector in nmi_watchdog off
3672 1 - turn hardlockup detector in nmi_watchdog on
3676 To disable both hard and soft lockup detectors,
3684 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3688 no4lvl [RISCV] Disable 4-level and 5-level paging modes. Forces
3689 kernel to use 3-level paging instead.
3691 no5lvl [X86-64,RISCV] Disable 5-level paging mode. Forces
3692 kernel to use 4-level paging instead.
3695 caches in the slab allocator. Saves per-node memory,
3706 noautogroup Disable scheduler automatic task group creation.
3712 Disable suspending of consoles during suspend and
3720 console_suspend, a printk module parameter to control
3726 [KNL] Disable object debugging
3728 nodsp [SH] Disable hardware DSP at boot time.
3730 noefi Disable EFI runtime services support.
3732 no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel.
3734 noexec [IA-64]
3736 noexec32 [X86-64]
3737 This affects only 32-bit executables.
3738 noexec32=on: enable non-executable mappings (default)
3740 noexec32=off: disable non-executable mappings
3747 nofpu [MIPS,SH] Disable hardware FPU at boot time.
3751 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3753 legacy floating-point registers on task switch.
3755 nohalt [IA-64] Tells the kernel not to use the power saving
3757 power-consumption. On the positive side, it reduces
3758 interrupt wake-up latency, which may improve performance
3760 real-time systems.
3770 compared. However, if this command-line option is
3776 nohibernate [HIBERNATION] Disable hibernation and resume.
3783 correctly or when doing power measurements to evaluate
3787 nohugeiomap [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.
3789 nohugevmalloc [KNL,X86,PPC,ARM64] Disable kernel huge vmalloc mappings.
3791 nohz= [KNL] Boottime enable/disable dynamic ticks
3811 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
3813 [Deprecated - use intremap=off]
3815 nointroute [IA-64]
3817 noinvpcid [X86] Disable the INVPCID cpu feature.
3819 noiotrap [SH] Disables trapped I/O port accesses.
3821 noirqdebug [X86-32] Disables the code which attempts to detect and
3822 disable unhandled interrupt sources.
3826 nojitter [IA-64] Disables jitter checking for ITC timers.
3833 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
3836 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
3838 nolapic [X86-32,APIC] Do not enable or use the local APIC.
3840 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
3842 nomca [IA-64] Disable machine check abort handling
3844 nomce [X86-32] Disable Machine Check Exception
3846 nomfgpt [X86-32] Disable Multi-Function General Purpose
3849 nomodeset Disable kernel modesetting. Most systems' firmware
3852 not load if they could possibly displace the pre-
3855 perform display-mode changes or accelerated rendering.
3859 nomodule Disable module load
3861 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
3865 nopat [X86] Disable PAT (page attribute table extension of
3868 nopcid [X86-64] Disable the PCID cpu feature.
3870 nopku [X86] Disable Memory Protection Keys CPU feature found
3873 nopti [X86-64]
3889 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
3895 nosbagart [IA-64]
3897 no-scroll [VGA] Disables scrollback.
3898 This is required for the Braillex ib80-piezo Braille
3901 nosgx [X86-64,SGX] Disables Intel SGX kernel support.
3904 Disable SMAP (Supervisor Mode Access Prevention)
3908 Disable SMEP (Supervisor Mode Execution Prevention)
3912 and disable the IO APIC. legacy for "maxcpus=0".
3914 nosmt [KNL,MIPS,PPC,S390] Disable symmetric multithreading (SMT).
3917 [KNL,X86,PPC] Disable symmetric multithreading (SMT).
3918 nosmt=force: Force disable SMT, cannot be undone
3919 via the sysfs control file.
3921 nosoftlockup [KNL] Disable the soft-lockup detector.
3924 [HW] Disable all mitigations for the Speculative Store Bypass vulnerability
3926 nospectre_bhb [ARM64] Disable all mitigations for Spectre-BHB (branch
3930 nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1
3934 nospectre_v2 [X86,PPC_E500,ARM64] Disable all mitigations for
3939 no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES] Disable paravirtualized
3949 [PPC] Don't flush the L1-D cache after accessing user data.
3952 Disable device dump. Device dump allows drivers to
3962 no-vmw-sched-clock
3963 [X86,PV_OPS] Disable paravirtualized VMware scheduler
3966 nowatchdog [KNL] Disable both lockup detectors, i.e.
3967 soft-lockup and NMI watchdog (hard-lockup).
3971 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
3979 enabling legacy floating-point and sse state.
4005 nptcg= [IA-64] Override max number of concurrent global TLB
4014 n. So during boot up some boot time memory for per-cpu
4015 variables need be pre-allocated for later physical cpu
4020 numa=off [KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only
4023 numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
4025 Allowed values are enable and disable
4030 See Documentation/admin-guide/sysctl/vm.rst for details.
4033 See Documentation/core-api/debugging-via-ohci1394.rst for more
4048 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
4052 boundary - index of last SLC block on Flex-OneNAND.
4054 lock - Configure if Flex-OneNAND boundary should be locked.
4065 [KNL] Boolean flag to control whether the page allocator
4068 running on a platform with a direct-mapped memory-side
4070 override/disable that behavior. The state of the flag
4074 page_owner= [KNL] Boot-time page_owner enabling option.
4080 page_poison= [KNL] Boot-time parameter changing the state of
4107 See Documentation/admin-guide/tainted-kernels.rst for
4128 parkbd.port= [HW] Parallel port number the keyboard adapter is
4131 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
4143 settings on that particular port), or 'nofifo'
4150 Configure VIA parallel port to operate in
4153 up parallel port mode and sets it to spp.
4159 Set to non-zero to probe primary and secondary ISA
4160 port ranges on PCI systems where no PCI PATA device
4165 Set to non-zero if a chip is present that snoops speed
4213 Set to non-zero to probe tertiary and further ISA
4214 port ranges on PCI systems. Disabled by default.
4224 the first port in the list above (0x1f0), and so on.
4229 Set to non-zero to probe QDI controllers. By default
4234 Set to non-zero to probe Winbond controllers. Use
4235 the standard I/O port (0x130) if 1, otherwise the
4236 value given is the I/O port to use (typically 0x1b0).
4281 bios [X86-32] force use of PCI BIOS, don't access
4283 has a non-standard PCI host bridge.
4284 nobios [X86-32] disallow use of PCI BIOS, only direct
4289 Mechanism 1 (config address in IO port 0xCF8,
4290 data in IO port 0xCFC, both 32-bit).
4292 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
4293 the function, IO port 0xCFA, also 8-bit, sets
4295 through ports 0xC000-0xCFFF).
4300 disable the use of PCIE advanced error reporting.
4301 nodomains [PCI] Disable support for multiple PCI
4302 root domains (aka PCI segments, in ACPI-speak).
4303 nommconf [X86] Disable use of MMCONFIG for PCI
4310 disable the use of MSI interrupts system-wide.
4311 noioapicquirk [APIC] Disable all boot interrupt quirks.
4315 primary IO-APIC for bridges that cannot disable
4318 noioapicreroute [APIC] Disable workaround that uses the
4322 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
4346 F0000h-100000h range.
4351 assign-busses [X86] Always assign all PCI bus
4372 <linux-pci@vger.kernel.org>.
4376 a bug to <linux-pci@vger.kernel.org>.
4388 bfsort Sort PCI devices into breadth-first order.
4391 nobfsort Don't sort PCI devices into breadth-first order.
4392 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
4393 tuning and use the BIOS-configured MPS defaults.
4403 configuration allows peer-to-peer DMA between
4406 that hot-added devices will work.
4421 A PCI-PCI bridge can be specified if resource
4427 for 4096-byte alignment.
4428 ecrc= Enable/disable PCIe ECRC (transaction layer
4429 end-to-end CRC checking). Only effective if
4430 OS has native AER control (either granted by
4452 realloc= Enable/disable reallocating PCI bridge resources
4460 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4464 port.
4485 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
4487 off Disable ASPM.
4491 pcie_ports= [PCIE] PCIe port services handling:
4496 dpc-native Use native PCIe service for DPC only. May
4498 compat Disable native PCIe services (PME, AER, DPC, PCIe
4501 pcie_port_pm= [PCIE] PCIe port power management handling:
4502 off Disable power management of all PCIe ports
4503 force Forcibly enable power management of all PCIe ports
4513 Keep all power-domains already enabled by bootloader on,
4518 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
4530 pirq= [SMP,APIC] Manual mp-table setup
4531 See Documentation/arch/x86/i386/IO-APIC.rst.
4533 plip= [PPT,NET] Parallel port network link
4535 See also Documentation/admin-guide/parport.rst.
4537 pmtmr= [X86] Manual setup of pmtmr I/O Port.
4554 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4563 { on | off | curr | res | no-curr | no-res }
4572 Ranges are in pairs (I/O port base and size).
4583 Format: <port>,<port>....
4585 powersave=off [PPC] This option disables power saving features.
4599 Disable Hardware Transactional Memory
4603 none - Limited to cond_resched() calls
4604 voluntary - Limited to cond_resched() and might_sleep() calls
4605 full - Any section that isn't explicitly preempt disabled
4608 print-fatal-signals=
4614 coredump - etc.
4617 you might want to try "ulimit -i unlimited".
4624 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4628 Disable console loglevel raise on oops, panic
4629 or lockdep-detected issues (only if lock debug is on).
4637 Control writing to /dev/kmsg.
4638 on - unlimited logging to /dev/kmsg from userspace
4639 off - logging to /dev/kmsg disabled
4640 ratelimit - ratelimit the logging
4644 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4647 Limit processor to maximum C-state
4651 Ignore the _CST method to determine C-states,
4658 Param: "schedule" - profile schedule points.
4659 Param: "sleep" - profile D-state sleeping (millisecs).
4661 Param: "kvm" - profile VM exits.
4662 Param: <number> - step/bucket size as a power of 2 for
4672 psi= [KNL] Enable or disable pressure stall information
4691 pti= [X86-64] Control Page Table Isolation of user and
4696 on - unconditionally enable
4697 off - unconditionally disable
4698 auto - kernel detects whether your CPU model is
4704 [KNL] Number of legacy pty's. Overwrites compiled-in
4707 quiet [KNL] Disable most log messages
4712 Disable RADIX GTSE feature and use hcall for TLB
4716 See Documentation/admin-guide/md.rst.
4719 See Documentation/admin-guide/blockdev/ramdisk.rst.
4724 [KNL] Disable trusting the use of the CPU's
4729 [KNL] Disable trusting the use of the a seed
4734 [KNL] Enable or disable kernel stack offset
4738 cross-syscall address exposures. This is only
4741 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4744 ras=option[,option,...] [KNL] RAS-specific options
4747 Disable the Correctable Errors Collector,
4750 rcu_nocbs[=cpu-list]
4755 enable the no-callback CPU mode, which prevents
4760 "p" for RCU-preempt, "s" for RCU-sched, and "g"
4764 and real-time workloads. It can also improve
4768 list of CPUs is set to no-callback mode from boot.
4772 no-callback mode from boot but the mode may be
4783 This improves the real-time response for the
4800 RCU grace-period cleanup.
4804 RCU grace-period initialization.
4808 RCU grace-period pre-initialization, that is,
4809 the propagation of recent CPU-hotplug changes up
4813 Set delay from grace-period initialization to
4826 soliciting quiescent-state help from
4838 Set the SCHED_FIFO priority of the RCU per-CPU
4841 and for the RCU grace-period kthreads (rcu_bh,
4843 set, valid values are 1-99 and the default is 1
4844 (the least-favored priority). Otherwise, when
4845 RCU_BOOST is not set, valid values are 0-99 and
4846 the default is zero (non-realtime operation).
4851 On callback-offloaded (rcu_nocbs) CPUs,
4854 use of the ->nocb_bypass list. However, in the
4855 common non-flooded case, RCU queues directly to
4856 the main ->cblist in order to avoid the extra
4857 overhead of the ->nocb_bypass list and its lock.
4859 a single jiffy, RCU pre-queues the callbacks into
4860 the ->nocb_bypass queue. The definition of "too
4869 batch limiting is re-enabled.
4873 RCU's force-quiescent-state scan will aggressively
4878 disable more aggressive help enlistment.
4881 Set the page-cache refill delay (in milliseconds)
4882 in response to low-memory conditions. The range
4886 Set the shift-right count to use to compute
4887 the callback-invocation batch limit bl from
4894 Please note that this callback-invocation batch
4895 limit applies only to non-offloaded callback
4901 Disable autobalancing of the rcu_node combining
4904 cache-to-cache transfer latencies.
4910 and for NUMA systems with large remote-access
4926 the wakeup overhead on the global grace-period
4928 each group's NOCB grace-period kthread.
4931 Cause the grace-period kthread to get an extra
4933 it should at force-quiescent-state time.
4946 this specifies an rcu_read_unlock()-time delay
4950 of RCU-protected pointers after the relevant
4960 per-CPU rcuc kthreads. Defaults to a non-zero
4964 But note that CONFIG_PREEMPT_RT=y kernels disable
4970 grace-period primitives such as call_rcu().
4981 grace-period primitives.
4984 Set test-start holdoff period. The purpose of
5002 Test the double-argument variant of kfree_rcu().
5004 rcuscale.kfree_rcu_test_single, both the single-
5005 and double-argument variants are tested.
5008 Test the single-argument variant of kfree_rcu().
5010 rcuscale.kfree_rcu_test_double, both the single-
5011 and double-argument variants are tested.
5025 does not affect the data-collection interval,
5030 Set number of RCU readers. The value -1 selects
5032 "n" less than -1 selects N-n+1, where N is again
5033 the number of CPUs. For example, -2 selects N
5034 (the number of CPUs), -3 selects N+1, and so on.
5035 A value of "n" less than or equal to -N selects
5048 complete. This is useful for hands-off automated
5055 Write-side holdoff between grace periods,
5060 Additional write-side holdoff between grace
5078 for RCU grace-period forward-progress testing
5085 Specify the fraction of a CPU-stall-warning
5086 period to do tight-loop forward-progress testing.
5090 forward-progress tests.
5094 need_resched() during tight-loop forward-progress
5098 Use conditional/asynchronous update-side
5102 Use expedited update-side primitives, if available.
5105 Use normal (non-expedited) asynchronous
5106 update-side primitives, if available.
5109 Use normal (non-expedited) synchronous
5110 update-side primitives, if available. If all
5114 they are all non-zero.
5122 Leak an RCU-protected pointer out of the reader.
5137 Set number of RCU callback-offload togglers.
5142 callback-offload toggling attempts.
5145 Set number of RCU readers. The value -1 selects
5146 N-1, where N is the number of CPUs. A value
5147 "n" less than -1 selects N-n-2, where N is again
5148 the number of CPUs. For example, -2 selects N
5149 (the number of CPUs), -3 selects N+1, and so on.
5152 Enable debug-object double-call_rcu() testing.
5155 Set time (s) after boot for CPU-hotplug testing.
5158 Set time (jiffies) between CPU-hotplug operations,
5159 or zero to disable CPU-hotplug testing.
5162 Set the number of read-then-exit kthreads used
5164 task-exit processing.
5167 The number of times in a given read-then-exit
5168 episode that a set of read-then-exit kthreads
5173 read-then-exit testing episodes.
5176 Set task-shuffle interval (s). Shuffling tasks
5177 allows some CPUs to go into dyntick-idle mode
5182 is useful for hands-off automated testing.
5186 warnings, zero to disable.
5191 any other stall-related activity. Note that
5197 in scheduling-while-atomic splats.
5206 Disable interrupts while stalling if set.
5210 grace-period kthread to test RCU CPU stall
5211 warnings, zero to disable. If both stall_cpu
5236 Test RCU's dyntick-idle handling. See also the
5285 Use expedited grace-period primitives, for
5289 real-time latency, and degrade energy efficiency.
5293 Use only normal grace-period primitives,
5296 real-time latency, CPU utilization, and
5298 increased grace-period latency. This parameter
5305 only normal grace-period primitives. No effect
5311 post-boot attempt at an expedited RCU grace
5312 period to instead use normal non-expedited
5313 grace-period processing.
5321 set to the default value of -1.
5324 Set the minimum number of callback-queuing-time
5325 lock-contention events per jiffy required to
5326 cause the RCU Tasks flavors to switch to per-CPU
5329 the default value of -1.
5334 of -1 allows this to be automatically (and
5342 number avoids disturbing real-time workloads,
5347 cancel laziness on that CPU. Use -1 to disable
5357 only printed prior to the stall-warning message
5358 for a given grace period. Disable with a value
5376 warning messages. Disable with a value less
5385 of zero will disable batching. Batching is
5393 disable batching. Batching is always disabled
5401 disable batching. Batching is always disabled
5413 force - Override the decision by the kernel to hide the
5441 Set test-start holdoff period. The purpose of
5450 but the default has already reduced the per-pass
5455 Set number of readers. The default value of -1
5464 Set the read-side critical-section duration,
5468 Specify the read-protection implementation to test.
5487 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
5495 reservetop= [X86-32]
5512 See Documentation/power/swsusp-and-swap-files.rst
5523 retbleed= [X86] Control mitigation of RETBleed (Arbitrary
5527 AMD-based UNRET and IBPB mitigations alone do not stop
5529 sibling threads. For that reason, STIBP is used on pro-
5533 off - no mitigation
5534 auto - automatically select a migitation
5535 auto,nosmt - automatically select a mitigation,
5539 ibpb - On AMD, mitigate short speculation
5544 ibpb,nosmt - Like "ibpb" above but will disable SMT
5548 unret - Force enable untrained return thunks,
5549 only effective on AMD f15h-f17h based
5551 unret,nosmt - Like unret, but will disable SMT when STIBP
5575 ring3mwait=disable
5576 [KNL] Disable ring 3 MONITOR/MWAIT feature on supported
5586 ro [KNL] Mount root device read-only on boot
5589 on Mark read-only kernel memory as read-only (default).
5590 off Leave read-only kernel memory writable for debugging.
5591 full Mark read-only kernel memory and aliases as read-only
5595 Enable the uart passthrough on the designated usb port
5597 debug-uart get routed to the D+ and D- pins of the usb
5598 port and the regular usb controller gets disabled.
5603 block/early-lookup.c for details.
5628 rw [KNL] Mount root device read-write on boot
5656 schedstats= [KNL,X86] Enable or disable scheduled statistics.
5657 Allowed values are enable and disable. This feature
5680 to 10 seconds for built-in smp_call_function()
5687 that requesting even small non-zero numbers of
5694 The default of -1 specifies a number of kthreads
5699 test before initiating CPU-hotplug operations.
5703 CPU-hotplug operations. Specifying zero (which
5704 is the default) disables CPU-hotplug operations.
5710 Non-zero values are useful for automated tests.
5723 preempt_disable() to disable CPU hotplug
5733 "wait" parameter. A value of -1 selects the
5734 default if all other weights are -1. However,
5736 value of -1 will instead select a weight of zero.
5741 non-zero "wait" parameter. See weight_single.
5754 non-zero "wait" parameter. See weight_single
5766 non-zero "wait" parameter. See weight_single
5773 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
5774 1 -- enable.
5775 Note: increases power consumption, thus should only be
5782 selinux= [SELINUX] Disable or enable SELinux at boot time.
5785 0 -- disable.
5786 1 -- enable.
5789 serialnumber [BUGS=X86-32]
5791 sev=option[,option...] [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
5799 to set it to "all" by meaning -- no limit here.
5805 simeth= [IA-64]
5815 Disable merging of slabs with similar size. May be
5819 layout control by attackers can usually be
5823 unchanged). Debug options disable merging on their
5880 using the csdlock_debug- kernel parameter.
5885 system. By default, let CSD-lock acquisition
5887 for this value provides a 5-minute timeout.
5889 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
5890 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
5891 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
5892 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
5893 smsc-ircc2.ircc_irq= [HW] IRQ line
5894 smsc-ircc2.ircc_dma= [HW] DMA channel
5895 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
5905 Default: -1 (no limit)
5908 [KNL] Should the soft-lockup detector generate panics.
5911 A value of 1 instructs the soft-lockup detector
5912 to panic the machine when a soft-lockup occurs. It is
5915 respective build-time switch to that functionality.
5918 [KNL] Should the soft-lockup detector generate
5922 sonypi.*= [HW] Sony Programmable I/O Control Device driver
5923 See Documentation/admin-guide/laptops/sonypi.rst
5925 spectre_v2= [X86] Control mitigation of Spectre variant 2
5930 on - unconditionally enable, implies
5932 off - unconditionally disable, implies
5934 auto - kernel detects whether your CPU model is
5946 Selecting 'off' will disable both the kernel and
5951 retpoline - replace indirect branches
5952 retpoline,generic - Retpolines
5953 retpoline,lfence - LFENCE; indirect branch
5954 retpoline,amd - alias for retpoline,lfence
5955 eibrs - Enhanced/Auto IBRS
5956 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
5957 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
5958 ibrs - use IBRS to protect kernel
5964 [X86] Control mitigation of Spectre variant 2
5968 on - Unconditionally enable mitigations. Is
5971 off - Unconditionally disable mitigations. Is
5974 prctl - Indirect branch speculation is enabled,
5976 per thread. The mitigation control state
5980 - Like "prctl" above, but only STIBP is
5986 - Same as "prctl" above, but all seccomp
5991 - Like "seccomp" above, but only STIBP is
5996 auto - Kernel selects the mitigation depending on
6005 [X86] Control RAS overflow mitigation on AMD Zen CPUs
6007 off - Disable mitigation
6008 microcode - Enable microcode mitigation only
6009 safe-ret - Enable sw-only safe RET mitigation (default)
6010 ibpb - Enable mitigation by issuing IBPB on
6012 ibpb-vmexit - Issue IBPB only on VMEXIT
6013 (cloud-specific mitigation)
6016 [HW] Control Speculative Store Bypass (SSB) Disable mitigation
6038 on - Unconditionally disable Speculative Store Bypass
6039 off - Unconditionally enable Speculative Store Bypass
6040 auto - Kernel detects whether the CPU model contains an
6046 prctl - Control Speculative Store Bypass per thread
6048 for a process by default. The state of the control
6050 seccomp - Same as "prctl" above, but all seccomp threads
6051 will disable SSB unless they explicitly opt out.
6058 on,auto - On Power8 and Power9 insert a store-forwarding
6062 off - No action.
6081 off - not enabled
6083 warn - the kernel will emit rate-limited warnings
6091 fatal - the kernel will send SIGBUS to applications
6096 ratelimit:N -
6113 Control the Special Register Buffer Data Sampling
6116 Certain CPUs are vulnerable to an MDS-like
6129 off: Disable mitigation and remove
6136 This kernel-boot parameter defaults to 128,
6137 but takes effect only when the low-order four
6154 instead of the compile-time CONFIG_NR_CPUS.
6158 grace-period sequence counter wrap for the
6159 srcu_data structure's ->srcu_gp_seq_needed field.
6170 expediting. Set to zero to disable automatic
6174 Specifies the number of no-delay instances
6181 Specifies the per-grace-period phase, number of
6182 non-sleeping polls of readers. Beyond this limit,
6188 Specifies number of microseconds of non-sleeping
6189 delay between each non-sleeping poll of readers.
6192 Specifies the number of update-side contention
6197 set for contention-based conversions to occur.
6200 Speculative Store Bypass Disable control
6207 force-on: Unconditionally enable mitigation for
6209 force-off: Unconditionally disable mitigation for
6225 disable the stack depot thereby saving the static memory
6232 stacktrace_filter=[function-list]
6234 will trace at boot up. function-list is a comma-separated
6242 Set the STI (builtin display/keyboard on the HP-PARISC
6244 as the initial boot-console.
6256 Enable or disable strict sigaltstack size checks
6276 originate from a privileged port (i.e. a port in the
6282 maximum port values.
6292 Control how the NFS server code allocates CPUs to
6304 to global on non-NUMA machines)
6319 /sys/power/pm_test). Only available when CONFIG_PM_DEBUG
6327 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
6329 <int> -- Number of I/O TLB slabs
6330 <int> -- Second integer after comma. Number of swiotlb
6332 to a power of 2.
6333 force -- force using of bounce buffers even if they
6335 noforce -- Never use bounce buffers (for debugging)
6350 Ignore sysrq setting - this boot parameter will
6358 cache size. See Documentation/networking/ip-sysctl.rst
6365 Specify "mem" (for Suspend-to-RAM) or "standby" (for
6370 wakeup-capable RTC alarm.
6376 -1: disable all active trip points in all thermal zones
6380 -1: disable all critical trip points in all thermal zones
6384 1: disable ACPI thermal control
6387 -1: disable all passive trip points
6393 <deci-seconds>: poll all this frequency
6415 Prevent the CPU-hotplug component of torturing
6419 Dump the ftrace buffer at torture-test shutdown,
6423 with rotating-rust storage.
6428 disables verbose-printk() sleeping.
6431 Duration of each verbose-printk() sleep in jiffies.
6449 https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
6487 local - Use the per CPU time stamp counter
6491 global - Event time stamps are synchronize across
6494 counter - Simple counting of events (1, 2, ..)
6498 uptime - Use jiffies as the time stamp.
6499 perf - Use the same clock that perf uses.
6500 mono - Use ktime_get_mono_fast_ns() for time stamps.
6501 mono_raw - Use ktime_get_raw_fast_ns() for time
6503 boot - Use ktime_get_boot_fast_ns() for time stamps.
6507 trace_event=[event-list]
6509 to facilitate early boot debugging. The event-list is a
6510 comma-separated list of trace events to enable. See
6513 trace_instance=[instance-info]
6533 trace_options=[option-list]
6534 [FTRACE] Enable or disable tracer options at boot.
6535 The option-list is a comma delimited list of options
6549 trace_trigger=[trigger-list]
6569 [FTRACE] enable this option to disable tracing when a
6584 Can be used to control the default behavior of the system
6586 See Documentation/admin-guide/mm/transhuge.rst
6594 - "tpm"
6595 - "tee"
6596 - "caam"
6606 - "kernel"
6607 - the same value as trusted.source: "tpm" or "tee"
6608 - "default"
6612 tsc= Disable clocksource stability checks for TSC.
6617 high-resolution timer mode on older hardware, and in
6620 Used to run time disable IRQ_TIME_ACCOUNTING on any
6626 [x86] nowatchdog: disable clocksource watchdog. Used
6647 tsx= [X86] Control Transactional Synchronization
6649 support TSX control.
6653 on - Enable TSX on the system. Although there are
6656 several previous speculation-related CVEs, and
6660 off - Disable TSX on the system. (Note that this
6668 auto - Disable TSX if X86_BUG_TAA is present,
6673 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
6676 tsx_async_abort= [X86,INTEL] Control mitigation for the TSX Async
6679 Similar to Micro-architectural Data Sampling (MDS)
6694 full - Enable TAA mitigation on vulnerable CPUs
6697 full,nosmt - Enable TAA mitigation and disable SMT on
6700 vulnerable to cross-thread TAA attacks.
6701 off - Unconditionally disable TAA mitigation
6703 On MDS-affected machines, tsx_async_abort=off can be
6705 are mitigated with the same mechanism so in order to disable
6715 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
6718 TurboGraFX parallel port interface
6720 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
6721 See also Documentation/input/devices/joystick-parport.rst
6723 udbg-immortal [PPC] When debugging early kernel crashes that
6729 Set number of hash buckets for UDP/UDP-Lite connections
6731 uhci-hcd.ignore_oc=
6733 Some badly-designed motherboards generate lots of
6742 unwind_debug [X86-64]
6750 (default -1 = authorized (same as 1),
6752 if device connected to internal port)
6756 for newly-detected USB devices (default 2). This
6784 [USB] Specifies timeout for the initial 64-byte
6788 usbcore.nousb [USB] Disable the USB subsystem
6791 [USB] A list of quirk entries to augment the built-in
6794 VendorID:ProductID:Flags. The IDs are 4-digit hex
6796 will change the built-in quirk; setting it if it is
6801 a 255-byte read);
6805 Set-Interface requests);
6824 (bInterval-1).
6836 Power Management);
6845 pause after every control message);
6847 delay after resetting its port);
6859 usb-storage.delay_use=
6863 usb-storage.quirks=
6865 override the built-in unusual_devs list. List
6868 and Product ID values (4-digit hex numbers) and
6870 to a common usb-storage quirk flag as follows:
6912 medium is write-protected).
6921 1 - undefined instruction events
6922 2 - system calls
6923 4 - invalid data aborts
6924 8 - SIGSEGV faults
6925 16 - SIGBUS faults
6939 vdso=0: disable VDSO mapping
6941 vdso32= [X86] Control the 32-bit vDSO
6942 vdso32=1: enable 32-bit VDSO
6943 vdso32=0 or vdso32=2: disable 32-bit VDSO
6953 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
6955 vector= [IA-64,SMP]
6987 vga= [BOOT,X86-32] Select a particular video mode
6989 Documentation/admin-guide/svga.rst.
7004 - Disable all of the above options
7022 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
7025 vsyscall= [X86-64]
7028 code). Most statically-linked binaries and older
7031 targets for exploits that can control RIP.
7052 see VGA-softcursor.txt. Default: 2 = underline.
7057 This is a 16-member array composed of values
7058 ranging from 0-255.
7063 This is a 16-member array composed of values
7064 ranging from 0-255.
7069 This is a 16-member array composed of values
7070 ranging from 0-255.
7075 Set system-wide default UTF-8 mode for all tty's.
7076 Default is 1, i.e. UTF-8 mode is enabled for all
7081 Format=<-1|0|1>
7082 Set system-wide default for whether a cursor
7083 is shown on new VTs. Default is -1,
7088 vt.italic= [VT] Default color for italic text; 0-15.
7091 vt.underline= [VT] Default color for underlined text; 0-15.
7095 see Documentation/watchdog/watchdog-parameters.rst
7096 or other driver-specific files in the
7110 Format: <cpu-list>
7124 Per-cpu work items which run for longer than this
7127 them from noticeably delaying other per-cpu work
7136 Per-cpu workqueues are generally preferred because
7138 locality; unfortunately, per-cpu workqueues tend to
7139 be more power hungry than unbound workqueues.
7141 Enabling this makes the per-cpu workqueues which
7142 were observed to contribute significantly to power
7144 power usage at the cost of small performance
7155 Documentation/core-api/workqueue.rst.
7168 forces round-robin CPU selection to flush out
7173 writecombine= [LOONGARCH] Control the MAT (Memory Access Type) of
7176 on - Enable writecombine, use WUC for ioremap_wc()
7177 off - Disable writecombine, use SUC for ioremap_wc()
7179 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
7183 xen_512gb_limit [KNL,X86-64,XEN]
7193 ide-disks -- unplug primary master IDE devices
7194 aux-ide-disks -- unplug non-primary-master IDE devices
7195 nics -- unplug network devices
7196 all -- unplug all emulated devices (NICs and IDE disks)
7197 unnecessary -- unplugging emulated devices is
7200 never -- do not unplug even if version check succeeds
7208 Select whether to always use non-faulting (safe) MSR
7224 [KNL,X86,XEN] Disable the vector callback for Xen
7228 Boolean option to control scrubbing pages before giving them back
7233 xen_timer_slop= [X86-64,XEN]
7256 Boolean parameter to disable using fifo event handling
7258 preferred over the 2-level event handling, as it is
7271 off Fallback to firmware control of XIVE interrupt
7275 xive.store-eoi=off [PPC]
7281 xhci-hcd.quirks [USB,KNL]