Lines Matching +full:can +full:- +full:disable
5 force -- enable ACPI if default was off
6 on -- enable ACPI but allow fallback to DT [arm64]
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
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
41 This mechanism can repair the evaluation result to make
58 Documentation/firmware-guide/acpi/debug.rst for more information about
81 can interfere with legacy drivers.
113 by unsupported hardware/firmware features can result in
116 This facility can be used to prevent such uncontrolled
121 Disable auto-serialization of AML methods
124 auto-serialization feature.
128 acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump
132 Disable installation of static SSDTs at early boot time
142 Ignore the ACPI-based watchdog interface (WDAT) and let
163 acpi_osi=! # disable all built-in OS vendor
165 acpi_osi=!! # enable all built-in OS vendor
167 acpi_osi= # disable all strings
169 'acpi_osi=!' can be used in combination with single or
171 vendor string(s). Note that such command can only
182 can make '_OSI("Windows 2000")' TRUE.
186 exist in the ACPI namespace. NOTE that such command can
191 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
194 'acpi_osi=!*' can be used in combination with single or
196 string(s). Note that such command can affect the
206 1. 'acpi_osi="Module Device" acpi_osi=!*' can make
208 2. 'acpi_osi=!* acpi_osi="Module Device"' can make
227 For broken nForce2 BIOS resulting in XT-PIC timer.
235 as soon as the kernel's real-mode entry point is called.
260 off: disable AGP support
265 See Documentation/sound/alsa-configuration.rst
272 align_va_addr= [X86-64]
277 CPU-intensive style benchmark, and it can vary highly in
280 32: only for 32-bit processes
281 64: only for 64-bit processes
282 on: enable for both 32- and 64-bit processes
283 off: disable for both 32- and 64-bit processes
299 Allow execve() of 32-bit applications and setting of the
301 subset of the CPUs support 32-bit EL0. When this
302 parameter is present, the set of CPUs supporting 32-bit
304 and hot-unplug operations may be restricted.
306 amd_iommu= [HW,X86-64]
309 fullflush - enable flushing of IO/TLB entries when
313 off - do not initialize any AMD IOMMU found in
315 force_isolation - Force device isolation for all
321 amd_iommu_dump= [HW,X86-64]
327 amd_iommu_intr= [HW,X86-64]
330 legacy - Use legacy interrupt remapping mode.
331 vapic - Use virtual APIC mode, which allows IOMMU
333 This mode requires kvm-amd.avic=1.
347 Power management functions (SPARCstation-4/5 + deriv.)
349 Disable APC CPU standby support. SPARCstation-Fox does
350 not play well with APC CPU idle - disable it if you have
357 when initialising the APIC and IO-APIC components.
358 For X86-32, this can also be used to specify an APIC
378 to set it to "all" by meaning -- no limit here.
387 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
390 arm64.nobti [ARM64] Unconditionally disable Branch Target
393 arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication
396 arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension
420 audit= [KNL] Enable the audit sub-system
422 0 | off - kernel audit is disabled and can not be
424 unset - kernel audit is initialized but disabled and
426 1 | on - kernel audit is initialized and partially
437 behavior is to disable the BAU (i.e. bau=0).
439 0 - Disable the BAU.
440 1 - Enable the BAU.
441 unset - Disable the BAU.
462 See Documentation/block/cmdline-partition.rst
470 Extended command line options can be added to an initrd
473 See Documentation/admin-guide/bootconfig.rst
476 Disable BERT OS support on buggy BIOSes.
479 Disable BGRT to avoid flickering OEM logo.
484 bttv.pll= See Documentation/admin-guide/media/bttv.rst
493 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
512 inclusive. See arch/mips/include/asm/pgtable-bits.h
519 cgroup_disable= [KNL] Disable a particular controller or optional feature
520 Format: {name of the controller(s) or feature(s) to disable}
522 - foo isn't auto-mounted if you mount all cgroups in
524 - foo isn't visible as an individually mountable
526 - if foo is an optional feature then the feature is
530 cut the overhead, others just disable the usage. So
532 Specifying "pressure" disables per-cgroup pressure
535 cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1
546 nosocket -- Disable socket memory accounting.
547 nokmem -- Disable kernel memory accounting.
552 0 -- check protection applied by kernel (includes
554 1 -- check protection requested by application.
556 Value can be changed at runtime via
568 force such clocks to be always-on nor does it reserve
572 information, see Documentation/driver-api/clk.rst.
574 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
591 [X86-32] pit,hpet,tsc;
598 [X86-64] hpet,tsc
603 Enable/disable the eventstream feature of the ARM
604 architected timer so that code using WFE-based polling
605 loops can be debugged more effectively on production
615 Disable CPUID feature X for the kernel. See
624 Also note the kernel might malfunction if you disable
627 cma=nn[MG]@[start[MG][-end[MG]]]
638 Sets the size of kernel per-numa memory area for
640 per-numa CMA altogether. And If this option is not
642 With per-numa CMA enabled, DMA users on node nid will
658 com20020= [HW,NET] ARCnet - COM20020 chipset
662 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
666 ARCnet - COM90xx chipset (memory-mapped buffers)
684 See Documentation/admin-guide/serial-console.rst for more
694 Start an early, polled-mode console on the 8250/16550
697 MMIO inter-register address stride is either 8-bit
698 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
702 the h/w is not re-initialized.
723 syscall, or to executing "dmesg -S --raw" or to reading
738 Enable/disable the CPU sampling based debugging.
739 0: default value, disable debugging
743 disable the cpuidle sub-system
749 disable the cpufreq sub-system
757 [X86] Delay for N microsec between assert and de-assert
767 [KNL] Using kexec, Linux can switch to a 'crash kernel'
772 [KNL, X86-64] Select a region under 4G first, and
775 See Documentation/admin-guide/kdump/kdump.rst for further details.
780 start-[end] where start and end are both
782 Documentation/admin-guide/kdump/kdump.rst for an example.
785 [KNL, X86-64] range could be above 4G. Allow kernel
792 [KNL, X86-64] range under 4G. When crashkernel=X,high
797 low memory is needed to make sure DMA buffers for 32-bit
802 0: to disable low allocation.
807 [KNL] Disable crypto self-tests
821 See also Documentation/input/devices/joystick-parport.rst
825 Documentation/admin-guide/dynamic-debug-howto.rst for
839 [KNL] verbose self-tests
842 self-tests.
844 1 will print _a lot_ more information - normally
850 [KNL] Disable object debugging
882 Format: { on, no-mount, off }
884 no-mount:
885 Filesystem is not registered but kernel clients can
886 access APIs and a crashkernel can be used to read
889 get a -EPERM as result when trying to register files
893 Default value is set in build-time with a kernel configuration.
909 Documentation/admin-guide/mm/hugetlbpage.rst.
939 can be useful when debugging issues that require an SLB
943 Dynamically disable ZONE_DMA32 on kernels compiled with
951 disable= [IPV6]
960 against bounds-checking flaws in the kernel's
963 off Disable hardened usercopy checks.
966 Disable RADIX MMU mode on POWER9
969 Disable RADIX GTSE feature and use hcall for TLB
973 Disable TLBIE instruction. Currently does not work
981 disable BSP to wake up multiple CPUs without
987 Disable Intel PMU counter freezing feature.
992 Disable Dynamic DMA Window support. Use this
1010 Disable PIN 1 of APIC timer
1011 Can be useful to work around chipset bugs.
1013 dis_ucode_ldr [X86] Disable the microcode loader.
1020 entries for DMA-API debugging code. One entry is
1021 required per DMA-API allocation. Use this if the
1022 DMA-API debugging code disables itself because the
1026 With this option the DMA-API debugging driver
1027 filter feature can be enabled at boot time. Just
1029 The filter can be disabled or changed to another
1041 Generic built-in EDID data sets are used, if one of
1046 available in Documentation/admin-guide/edid.rst. An EDID
1058 Control how the dt_cpu_ftrs device-tree binding is
1068 what data is available or for reverse-engineering.
1073 Documentation/admin-guide/dynamic-debug-howto.rst
1076 nopku [X86] Disable Memory Protection Keys CPU feature found
1090 determined by stdout-path property in device tree's
1095 Start an early, polled-mode console on a Cadence
1106 Start an early, polled-mode console on the 8250/16550
1108 MMIO inter-register address stride is either 8-bit
1109 (mmio) or 32-bit (mmio32 or mmio32be).
1117 Start an early, polled-mode console on a pl011 serial
1121 the driver will use only 32-bit accessors to read/write
1125 Start an early, polled-mode console on a meson serial
1131 Start an early, polled-mode console on an msm serial
1137 Start an early, polled-mode console on an msm serial
1143 Start an early, polled-mode console on a serial port
1149 Start an early, polled-mode console on a serial port
1155 Use RISC-V SBI (Supervisor Binary Interface) for early
1173 Start an early, polled-mode console on a lantiq serial
1187 Start an early, polled-mode, output-only console on the
1192 Start an early, polled-mode console on the
1198 Start an early, polled-mode console on a Qualcomm
1206 coherent non-x86 systems that use system memory for
1231 Append ",keep" to not disable it when the real console
1234 Only one of vga, efi, serial, or usb debug port can
1242 You can find the port for a given device in
1252 The xen output can only be used by Xen PV guests.
1254 The sclp output can only be used on s390.
1264 off: disable H/W event reporting through EDAC.
1275 but can only be used if the backing tty is available
1287 disable_early_pci_dma: disable the busmaster bit on all
1289 nochunk: disable reading files in "chunks" in the EFI
1290 boot stub, as chunking can cause problems with some
1292 noruntime : disable EFI runtime services support
1296 claim. Specify efi=nosoftreserve to disable this
1304 Using this parameter you can use more than 50% of
1317 attribute is added to range 0x100000000-0x180000000 and
1318 0x10a0000000-0x1120000000.
1322 range 0x240000000-0x43fffffff.
1324 Using this parameter you can do debugging of EFI memmap
1325 related features. For example, you can do debugging of
1334 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1340 elanfreq= [X86-32]
1348 See Documentation/admin-guide/kdump/kdump.rst for details.
1357 Can be useful to work around chipset bugs
1364 0 -- permissive (log only, no denials).
1365 1 -- enforcing (deny and log).
1367 Value can be changed at runtime via
1371 Disable Error Record Serialization Table (ERST)
1389 See also Documentation/fault-injection/.
1393 See Documentation/admin-guide/sysctl/net.rst for
1397 See Documentation/admin-guide/blockdev/floppy.rst.
1400 [IA-64] Avoid check_sal_cache_flush which may hang on
1405 forcepae [X86-32]
1407 Many Pentium M systems disable PAE but may have a
1424 ftrace_filter=[function-list]
1426 tracer at boot up. function-list is a comma separated
1427 list of functions. This list can be changed at run
1431 ftrace_notrace=[function-list]
1433 function-list. This list can be changed at run time
1437 ftrace_graph_filter=[function-list]
1440 function-list is a comma separated list of functions
1441 that can be changed at run time by the
1444 ftrace_graph_notrace=[function-list]
1446 function-list. This list is a comma separated list of
1447 functions that can be changed at run time by the
1453 can be changed at run time by the max_graph_depth file
1466 off -- Don't create device links from firmware info.
1467 permissive -- Create device links from firmware info
1470 on -- Create device links from firmware info and use it
1472 rpm -- Like "on", but also use to order runtime PM.
1483 See also Documentation/input/devices/joystick-parport.rst
1487 gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
1491 gcov_persist= [GCOV] When non-zero (default), profiling data for
1524 gpio-mockup.gpio_mockup_ranges
1529 [KNL] Should the hard-lockup detector generate
1535 for 64-bit NUMA, off otherwise.
1538 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1544 Disable Hardware Error Source Table (HEST) support;
1545 corresponding firmware-first mode error processing
1553 highres= [KNL] Enable/disable high resolution timer mode.
1559 hpet= [X86-32,HPET] option to control HPET usage
1560 Format: { enable (default) | disable | force |
1562 disable: disable HPET and use PIT instead
1576 boot-time allocation of gigantic hugepages is skipped.
1584 Documentation/admin-guide/mm/hugetlbpage.rst.
1591 hugepagesz=X hugepages=Y can be specified once for
1594 Documentation/admin-guide/mm/hugetlbpage.rst.
1603 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1604 option. The value selected by this boot parameter can
1609 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1636 (disabled by default, and as a pre-condition
1638 i8042.direct [HW] Put keyboard port into non-translated mode
1639 i8042.dumbkbd [HW] Pretend that controller can only read data from
1644 i8042.noloop [HW] Disable the AUX Loopback command while probing
1652 suspend-to-ram transitions, only during s2r
1687 -1 -- never invert brightness
1688 0 -- machine default
1689 1 -- force brightness inversion
1694 ide-core.nodma= [HW] (E)IDE subsystem
1700 ide-generic.probe-mask= [HW] (E)IDE subsystem
1712 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1717 Poll forces a polling idle loop that can slightly
1723 idle=nomwait: Disable mwait for CPU C-states
1740 legacy only accept legacy-NaN binaries, if supported
1742 2008 only accept 2008-NaN binaries, if supported
1751 'relaxed' straps the emulator for both legacy-NaN and
1752 2008-NaN, whereas 'strict' enables legacy-NaN only on
1761 Ignore loglevel setting - this will print /all/
1769 print warning at first misuse. Can be changed via
1825 Formats: { "ima" | "ima-ng" | "ima-sig" }
1826 Default: "ima-ng"
1838 different crypto accelerators. This option can be used
1846 different crypto accelerators. This option can be used
1858 initcall_blacklist= [KNL] Do not execute a comma-separated list of
1859 initcall functions. Useful for debugging built-in
1882 default (disallow access to all but pkey 0). Can
1892 0 -- basic integrity auditing messages. (Default)
1893 1 -- additional integrity auditing messages.
1899 Disable intel iommu driver.
1906 forcedac [X86-64]
1908 for io virtual address below 32-bit forcing dual
1910 than 32-bit addressing. The default is to look
1911 for translation below 32-bit and if not available
1929 could harm performance of some high-throughput
1936 Disable bounce buffer for untrusted devices such as
1943 1 to 9 specify maximum depth of C-state.
1946 disable
1953 used along with the hardware-managed P-states (HWP)
1957 in favor of acpi-cpufreq. Forcing the intel_pstate driver
1958 instead of acpi-cpufreq may disable platform features, such
1960 P-States information being indicated to OSPM and therefore
1963 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
1976 Allow per-logical-CPU P-State performance control limits using
1979 intremap= [X86-64, Intel-IOMMU]
1981 off disable Interrupt Remapping
1982 nosid disable Source ID checking
1984 BIOS x2APIC opt-out request will be ignored
1985 nopost disable Interrupt Posting
1987 iomem= Disable strict checking of access to MMIO memory
2004 Disable IOMMU bypass, using IOMMU for PCI devices.
2008 0 - Lazy mode.
2014 1 - Strict mode (default).
2021 0 - Use IOMMU translation for DMA.
2022 1 - Bypass the IOMMU for DMA.
2023 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2025 io7= [HW] IO7 for Marvel-based Alpha systems
2040 See Documentation/admin-guide/nfs/nfsroot.rst.
2064 Enables support for pseudo-NMIs in the kernel. This
2083 [Deprecated - use cpusets instead]
2084 Format: [flag-list,]<cpu-list>
2090 Disable the tick when a single task runs.
2107 advised to use cpusets instead to disable scheduler load
2109 It offers a much more flexible interface where CPUs can
2112 You can move a process onto or off an "isolated" CPU via
2115 "number of CPUs in system - 1".
2141 The format of <cpu-list> is described above.
2145 ivrs_ioapic [HW,X86-64]
2146 Provide an override to the IOAPIC-ID<->DEVICE-ID
2148 example, to map IOAPIC-ID decimal 10 to
2152 ivrs_hpet [HW,X86-64]
2153 Provide an override to the HPET-ID<->DEVICE-ID
2155 example, to map HPET-ID decimal 0 to
2159 ivrs_acpihid [HW,X86-64]
2160 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2162 example, to map UART-HID:UID AMD0020:0 to
2182 kernelcore= [KNL,X86,IA-64,PPC]
2185 the kernel for non-movable allocations. The requested
2195 subsystem. Note that allocations like PTEs-from-HighMem
2203 for non-movable allocations and remaining memory is used
2214 gdb or control-c on the dbgp connection. When
2215 not using this parameter you use sysrq-g to break into
2220 or a supported polling keyboard driver (non-usb).
2230 characters and can work in polling mode, you can use
2247 Configure the RouterBoard 532 series on-chip
2250 kmemleak= [KNL] Boot-time kmemleak enable/disable
2256 kprobe_event=[probe-list]
2258 The probe-list is a semicolon delimited list of probe
2304 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
2307 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
2309 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
2311 kvm-arm.mode=
2314 nvhe: Standard nVHE-based mode, without support for
2317 protected: nVHE-based mode with support for guests whose
2324 kvm-arm.vgic_v3_group0_trap=
2325 [KVM,ARM] Trap guest accesses to GICv3 group-0
2328 kvm-arm.vgic_v3_group1_trap=
2329 [KVM,ARM] Trap guest accesses to GICv3 group-1
2332 kvm-arm.vgic_v3_common_trap=
2336 kvm-arm.vgic_v4_enable=
2348 kvm-intel.ept= [KVM,Intel] Disable extended page tables
2352 kvm-intel.emulate_invalid_guest_state=
2353 [KVM,Intel] Disable emulation of invalid guest state.
2354 Ignored if kvm-intel.enable_unrestricted_guest=1, as
2360 kvm-intel.flexpriority=
2361 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
2364 kvm-intel.nested=
2368 kvm-intel.unrestricted_guest=
2369 [KVM,Intel] Disable unrestricted guest feature
2373 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2374 CVE-2018-3620.
2380 VMEXIT and VMENTER can leak host memory.
2385 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
2452 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2458 lapic [X86-32,APIC] Enable the local APIC even if BIOS
2462 value for LAPIC timer one-shot implementation. Default
2470 libata.dma=0 Disable all PATA and SATA DMA
2497 first fan-out link behind PMP device. It does not
2504 The following configurations can be forced.
2511 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2523 hot-unplug link recovery
2529 * disable: Disable this device.
2538 call memblock_remove on the regions marked with no-map
2566 Set the number of locking read-acquisition kthreads.
2571 Set the number of locking write-acquisition kthreads.
2574 Set time (s) after boot for CPU-hotplug testing.
2577 Set time (s) between CPU-hotplug operations, or
2578 zero to disable CPU-hotplug testing.
2581 Set task-shuffle interval (jiffies). Shuffling
2582 tasks allows some CPUs to go into dyntick-idle
2587 is useful for hands-off automated testing.
2609 console loglevel will be printed to the console. It can
2620 7 (KERN_DEBUG) debug-level messages
2630 logo.nologo [FB] Disables display of the built-in Linux logo.
2638 lp=auto printer driver. 'lp=reset' (which can be
2648 an IEEE 1284-compliant printer is attached; if
2654 time-consuming boot-time autodetection (up to 250 ms per
2675 machvec= [IA-64] Force the use of a particular machine-vector
2681 Example: machtype=lemote-yeeloong-2f-7inch
2689 bootup you can bring up the other plugged cpu by executing
2696 (loop.max_loop) unconditionally pre-created at init time. The default
2699 devices can be requested on-demand with the
2700 /dev/loop-control interface.
2702 mce [X86-32] Machine Check Exception
2704 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.rst
2707 See Documentation/admin-guide/md.rst.
2714 Control mitigation for the Micro-architectural Data
2718 internal buffers which can forward information to a
2722 forwarded data can be used in a cache side channel
2729 full - Enable MDS mitigation on vulnerable CPUs
2730 full,nosmt - Enable MDS mitigation and disable
2732 off - Unconditionally disable MDS mitigation
2734 On TAA-affected machines, mds=off can be prevented by
2736 mitigated with the same mechanism so in order to disable
2743 For details see: Documentation/admin-guide/hw-vuln/mds.rst
2762 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
2767 per-device physically contiguous DMA buffers.
2775 See Documentation/admin-guide/mm/memory-hotplug.rst.
2779 Such memmap=exactmap lines can be constructed based on
2788 Multiple different regions can be specified,
2800 Example: Exclude memory from 0x18690000-0x1869ffff
2814 memmap=<size>%<offset>-<oldtype>+<newtype>
2816 from <oldtype> to <newtype>. If "-<oldtype>" is left
2831 repeatable BIOS-originated corruption always
2832 affects the same memory, you can use memmap=
2848 default : 0 <disable>
2856 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
2864 Refer to Documentation/virt/kvm/amd-memory-encryption.rst
2865 for details on when memory encryption can be activated.
2868 s2idle - Suspend-To-Idle
2869 shallow - Power-On Suspend or equivalent (if supported)
2870 deep - Suspend-To-RAM or equivalent (if supported)
2871 See Documentation/admin-guide/pm/sleep-states.rst.
2874 See Documentation/admin-guide/media/meye.rst.
2876 mfgpt_irq= [IA-32] Specify the IRQ to use for the
2877 Multi-Function General Purpose Timers on AMD Geode
2880 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
2883 problem by letting the user disable the workaround.
2894 0 - The attached screen is the 3.5" TFT
2895 1 - The attached screen is the 7" TFT
2896 2 - The VGA Shield is attached (1024x768)
2900 b - Enable backlight. The TFT backlight pin will be
2904 c - Enable the s3c camera interface.
2905 t - Reserved for enabling touchscreen support. The
2907 kernel as of 2.6.30, a preliminary port can be found
2909 https://repo.or.cz/w/linux-2.6/mini2440.git
2914 arch-independent options, each of which is an
2915 aggregation of existing arch-specific options.
2918 Disable all optional CPU mitigations. This
2928 ssbd=force-off [ARM64]
2948 have other ways of avoiding SMT-based attacks.
2983 full - Enable mitigation on vulnerable CPUs
2985 full,nosmt - Enable mitigation and disable SMT on
2988 off - Unconditionally disable mitigation
2991 mmio_stale_data=off can be prevented by an active
2994 disable this mitigation, you need to specify
3001 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3009 module_blacklist= [KNL] Do not load a comma-separated list of
3023 movablecore= [KNL,X86,IA-64,PPC]
3034 movable_node [KNL] Boot-time switch to make hotplugable memory
3041 Format: <name>,<region-number>,<size>,<offset>
3044 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3059 result can cause aggregate CPU usage on the system to go up, down or
3062 More aggressive page replacement can reduce direct reclaims which
3067 The range of acceptible values are 1-16. Always start with lower
3068 values in the 2-6 range. Higher values should be justified with
3070 of direct reclaims (in latency) that occur can be higher due to
3073 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
3077 boundary - index of last SLC block on Flex-OneNAND.
3079 lock - Configure if Flex-OneNAND boundary should be locked.
3086 See arch/arm/mach-s3c2412/mach-jive.c
3114 something different and driver-specific.
3120 0 to disable accounting
3125 See Documentation/admin-guide/nfs/nfsroot.rst.
3127 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3128 See Documentation/admin-guide/nfs/nfsroot.rst.
3131 See Documentation/admin-guide/nfs/nfsroot.rst.
3155 [NFS] enable 64-bit inode numbers.
3156 If zero, the NFS client will fake up a 32-bit inode
3158 of returning the full 64-bit number.
3159 The default is to return 64-bit inode numbers.
3172 that the client can send to the NFSv4.1 server.
3182 disabling idmapping, which can make migration from
3189 [NFS4] Specify an additional fixed unique ident-
3190 ification string that NFSv4 clients can insert into
3220 driver. A non-zero value sets the minimum interval
3232 NMI stack-backtrace request.
3241 0 - turn hardlockup detector in nmi_watchdog off
3242 1 - turn hardlockup detector in nmi_watchdog on
3246 To disable both hard and soft lockup detectors,
3251 These settings can be accessed at runtime via
3259 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3263 no5lvl [X86-64] Disable 5-level paging mode. Forces
3264 kernel to use 4-level paging instead.
3270 Disable suspending of consoles during suspend and
3272 messages can reach various consoles while the rest
3284 Disable device dump. Device dump allows drivers to
3285 append dump data to vmcore so you can collect driver
3286 specified debug info. Drivers can append the data
3289 device dump can help save memory but the driver debug
3295 caches in the slab allocator. Saves per-node memory,
3306 noautogroup Disable scheduler automatic task group creation.
3315 nodelayacct [KNL] Disable per-task delay accounting
3317 nodsp [SH] Disable hardware DSP at boot time.
3319 noefi Disable EFI runtime services support.
3321 no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel.
3323 noexec [IA-64]
3326 On X86-32 available only on PAE configured kernels.
3327 noexec=on: enable non-executable mappings (default)
3328 noexec=off: disable non-executable mappings
3331 Disable SMAP (Supervisor Mode Access Prevention)
3335 Disable SMEP (Supervisor Mode Execution Prevention)
3338 noexec32 [X86-64]
3339 This affects only 32-bit executables.
3340 noexec32=on: enable non-executable mappings (default)
3342 noexec32=off: disable non-executable mappings
3345 nofpu [MIPS,SH] Disable hardware FPU at boot time.
3347 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3349 legacy floating-point registers on task switch.
3351 nohugeiomap [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.
3353 nosmt [KNL,S390] Disable symmetric multithreading (SMT).
3356 [KNL,X86] Disable symmetric multithreading (SMT).
3357 nosmt=force: Force disable SMT, cannot be undone
3360 nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1
3364 nospectre_v2 [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for
3370 [HW] Disable all mitigations for the Speculative Store Bypass vulnerability
3373 [PPC] Don't flush the L1-D cache after accessing user data.
3377 enabling legacy floating-point and sse state.
3402 nohalt [IA-64] Tells the kernel not to use the power saving
3404 power-consumption. On the positive side, it reduces
3405 interrupt wake-up latency, which may improve performance
3407 real-time systems.
3416 difficult since unequal pointers can no longer be
3417 compared. However, if this command-line option is
3423 nohibernate [HIBERNATION] Disable hibernation and resume.
3425 nohz= [KNL] Boottime enable/disable dynamic ticks
3441 noirqdebug [X86-32] Disables the code which attempts to detect and
3442 disable unhandled interrupt sources.
3452 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
3454 [Deprecated - use intremap=off]
3456 nointroute [IA-64]
3458 noinvpcid [X86] Disable the INVPCID cpu feature.
3460 nojitter [IA-64] Disables jitter checking for ITC timers.
3462 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
3464 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
3467 no-vmw-sched-clock
3468 [X86,PV_OPS] Disable paravirtualized VMware scheduler
3471 no-steal-acc [X86,PV_OPS,ARM64] Disable paravirtualized steal time
3475 nolapic [X86-32,APIC] Do not enable or use the local APIC.
3477 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
3482 nomca [IA-64] Disable machine check abort handling
3484 nomce [X86-32] Disable Machine Check Exception
3486 nomfgpt [X86-32] Disable Multi-Function General Purpose
3489 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
3493 nomodule Disable module load
3495 nopat [X86] Disable PAT (page attribute table extension of
3498 nopcid [X86-64] Disable the PCID cpu feature.
3503 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
3506 nordrand [X86] Disable kernel use of the RDRAND and
3514 no-scroll [VGA] Disables scrollback.
3515 This is required for the Braillex ib80-piezo Braille
3518 nosbagart [IA-64]
3520 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
3523 and disable the IO APIC. legacy for "maxcpus=0".
3525 nosoftlockup [KNL] Disable the soft-lockup detector.
3529 nowatchdog [KNL] Disable both lockup detectors, i.e.
3530 soft-lockup and NMI watchdog (hard-lockup).
3534 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
3542 2. PIC interrupts also depend on CPU0. CPU0 can't be
3547 If the dependencies are under your control, you can
3552 cycles, each HW thread of the CTOP can run
3559 nptcg= [IA-64] Override max number of concurrent global TLB
3567 runtime you can physically add extra cpu until it reaches
3568 n. So during boot up some boot time memory for per-cpu
3569 variables need be pre-allocated for later physical cpu
3574 numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing.
3575 Allowed values are enable and disable
3578 'node', 'default' can be specified
3579 This can be set from sysctl after boot.
3580 See Documentation/admin-guide/sysctl/vm.rst for details.
3583 See Documentation/core-api/debugging-via-ohci1394.rst for more
3622 running on a platform with a direct-mapped memory-side
3623 cache, and this parameter can be used to
3624 override/disable that behavior. The state of the flag
3625 can be read from sysfs at:
3628 page_owner= [KNL] Boot-time page_owner enabling option.
3631 we can turn it on.
3634 page_poison= [KNL] Boot-time parameter changing the state of
3647 User can chose combination of the following bits:
3660 The optional switch "nousertaint" can be utilized to
3664 See Documentation/admin-guide/tainted-kernels.rst for
3665 extra details on the taint flags that users can pick
3671 pelt= [KNL] Boot-time parameter changing the PELT half life in ms
3678 Run kdump after running panic-notifiers and dumping
3682 because some panic notifiers can make the crashed
3697 possible conflicts). You can specify the base
3723 See also Documentation/admin-guide/blockdev/paride.rst.
3742 addresses can be specified after the base
3752 bios [X86-32] force use of PCI BIOS, don't access
3754 has a non-standard PCI host bridge.
3755 nobios [X86-32] disallow use of PCI BIOS, only direct
3761 data in IO port 0xCFC, both 32-bit).
3763 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
3764 the function, IO port 0xCFA, also 8-bit, sets
3766 through ports 0xC000-0xCFFF).
3770 enabled, this kernel boot option can be used to
3771 disable the use of PCIE advanced error reporting.
3772 nodomains [PCI] Disable support for multiple PCI
3773 root domains (aka PCI segments, in ACPI-speak).
3774 nommconf [X86] Disable use of MMCONFIG for PCI
3780 enabled, this kernel boot option can be used to
3781 disable the use of MSI interrupts system-wide.
3782 noioapicquirk [APIC] Disable all boot interrupt quirks.
3786 primary IO-APIC for bridges that cannot disable
3789 noioapicreroute [APIC] Disable workaround that uses the
3793 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
3811 assigned automatically to PCI devices. You can
3817 F0000h-100000h range.
3818 lastbus=N [X86] Scan all buses thru bus #N. Can be
3822 assign-busses [X86] Always assign all PCI bus
3843 skip_isa_align [X86] do not align io start addr, so can
3850 bfsort Sort PCI devices into breadth-first order.
3853 nobfsort Don't sort PCI devices into breadth-first order.
3854 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
3855 tuning and use the BIOS-configured MPS defaults.
3862 or bus can support) for best performance.
3865 configuration allows peer-to-peer DMA between
3868 that hot-added devices will work.
3883 A PCI-PCI bridge can be specified if resource
3889 for 4096-byte alignment.
3890 ecrc= Enable/disable PCIe ECRC (transaction layer
3891 end-to-end CRC checking).
3912 realloc= Enable/disable reallocating PCI bridge resources
3920 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
3927 can resize a BAR to allow access to all VRAM.
3945 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
3947 off Disable ASPM.
3956 dpc-native Use native PCIe service for DPC only. May
3958 compat Disable native PCIe services (PME, AER, DPC, PCIe
3962 off Disable power management of all PCIe ports
3973 Keep all power-domains already enabled by bootloader on,
3979 See Documentation/admin-guide/blockdev/paride.rst.
3981 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
3994 See Documentation/admin-guide/blockdev/paride.rst.
3997 See Documentation/admin-guide/blockdev/paride.rst.
3999 pirq= [SMP,APIC] Manual mp-table setup
4000 See Documentation/x86/i386/IO-APIC.rst.
4004 See also Documentation/admin-guide/parport.rst.
4015 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4024 { on | off | curr | res | no-curr | no-res }
4060 Disable Hardware Transactional Memory
4062 print-fatal-signals=
4068 coredump - etc.
4071 you might want to try "ulimit -i unlimited".
4078 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4083 on - unlimited logging to /dev/kmsg from userspace
4084 off - logging to /dev/kmsg disabled
4085 ratelimit - ratelimit the logging
4089 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4092 Limit processor to maximum C-state
4096 Ignore the _CST method to determine C-states,
4103 Param: "schedule" - profile schedule points.
4104 Param: "sleep" - profile D-state sleeping (millisecs).
4106 Param: "kvm" - profile VM exits.
4107 Param: <number> - step/bucket size as a power of 2 for
4117 psi= [KNL] Enable or disable pressure stall information
4137 See Documentation/admin-guide/blockdev/paride.rst.
4139 pti= [X86-64] Control Page Table Isolation of user and
4144 on - unconditionally enable
4145 off - unconditionally disable
4146 auto - kernel detects whether your CPU model is
4151 nopti [X86-64]
4155 [KNL] Number of legacy pty's. Overwrites compiled-in
4158 quiet [KNL] Disable most log messages
4163 See Documentation/admin-guide/md.rst.
4166 See Documentation/admin-guide/blockdev/ramdisk.rst.
4171 [KNL] Enable or disable trusting the use of the
4177 [KNL] Enable or disable trusting the use of a
4182 ras=option[,option,...] [KNL] RAS-specific options
4185 Disable the Correctable Errors Collector,
4190 except that the string "all" can be used to
4194 the specified list of CPUs to be no-callback CPUs.
4197 purpose, where "x" is "p" for RCU-preempt, and
4198 "s" for RCU-sched, and "N" is the CPU number.
4200 which can be useful for HPC and real-time
4201 workloads. It can also improve energy efficiency
4209 This improves the real-time response for the
4226 RCU grace-period cleanup.
4230 RCU grace-period initialization.
4234 RCU grace-period pre-initialization, that is,
4235 the propagation of recent CPU-hotplug changes up
4240 per-CPU rcuc kthreads. Defaults to a non-zero
4245 Disable autobalancing of the rcu_node combining
4248 cache-to-cache transfer latencies.
4254 and for NUMA systems with large remote-access
4267 Set delay from grace-period initialization to
4280 soliciting quiescent-state help from
4292 Set the SCHED_FIFO priority of the RCU per-CPU
4295 and for the RCU grace-period kthreads (rcu_bh,
4297 set, valid values are 1-99 and the default is 1
4298 (the least-favored priority). Otherwise, when
4299 RCU_BOOST is not set, valid values are 0-99 and
4300 the default is zero (non-realtime operation).
4306 the wakeup overhead on the global grace-period
4308 each group's NOCB grace-period kthread.
4316 batch limiting is re-enabled.
4320 RCU's force-quiescent-state scan will aggressively
4325 disable more aggressive help enlistment.
4334 Lazy RCU callbacks are those which RCU can
4338 Cause the grace-period kthread to get an extra
4340 it should at force-quiescent-state time.
4346 this specifies an rcu_read_unlock()-time delay
4350 of RCU-protected pointers after the relevant
4360 grace-period primitives such as call_rcu().
4371 grace-period primitives.
4374 Set test-start holdoff period. The purpose of
4393 Set number of RCU readers. The value -1 selects
4395 "n" less than -1 selects N-n+1, where N is again
4396 the number of CPUs. For example, -2 selects N
4397 (the number of CPUs), -3 selects N+1, and so on.
4398 A value of "n" less than or equal to -N selects
4411 complete. This is useful for hands-off automated
4418 Write-side holdoff between grace periods,
4435 Enable RCU grace-period forward-progress testing
4439 Specify the fraction of a CPU-stall-warning
4440 period to do tight-loop forward-progress testing.
4444 forward-progress tests.
4448 need_resched() during tight-loop forward-progress
4452 Use conditional/asynchronous update-side
4456 Use expedited update-side primitives, if available.
4459 Use normal (non-expedited) asynchronous
4460 update-side primitives, if available.
4463 Use normal (non-expedited) synchronous
4464 update-side primitives, if available. If all
4468 they are all non-zero.
4476 Leak an RCU-protected pointer out of the reader.
4477 This can of course result in splats, and is
4491 Set number of RCU readers. The value -1 selects
4492 N-1, where N is the number of CPUs. A value
4493 "n" less than -1 selects N-n-2, where N is again
4494 the number of CPUs. For example, -2 selects N
4495 (the number of CPUs), -3 selects N+1, and so on.
4498 Enable debug-object double-call_rcu() testing.
4501 Set time (s) after boot for CPU-hotplug testing.
4504 Set time (jiffies) between CPU-hotplug operations,
4505 or zero to disable CPU-hotplug testing.
4508 Set the number of read-then-exit kthreads used
4510 task-exit processing.
4513 The number of times in a given read-then-exit
4514 episode that a set of read-then-exit kthreads
4519 read-then-exit testing episodes.
4522 Set task-shuffle interval (s). Shuffling tasks
4523 allows some CPUs to go into dyntick-idle mode
4528 is useful for hands-off automated testing.
4532 warnings, zero to disable.
4537 to any other stall-related activity.
4543 Disable interrupts while stalling if set.
4547 grace-period kthread to test RCU CPU stall
4548 warnings, zero to disable. If both stall_cpu
4573 Test RCU's dyntick-idle handling. See also the
4599 Use expedited grace-period primitives, for
4602 but can increase CPU utilization, degrade
4603 real-time latency, and degrade energy efficiency.
4607 Use only normal grace-period primitives,
4610 real-time latency, CPU utilization, and
4611 energy efficiency, but can expose users to
4612 increased grace-period latency. This parameter
4619 only normal grace-period primitives. No effect
4626 number avoids disturbing real-time workloads,
4631 messages. Disable with a value less than or equal
4643 force - Override the decision by the kernel to hide the
4671 Set test-start holdoff period. The purpose of
4680 but the default has already reduced the per-pass
4685 Set number of readers. The default value of -1
4694 Set the read-side critical-section duration,
4698 Specify the read-protection implementation to test.
4711 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
4719 reservetop= [X86-32]
4741 See Documentation/power/swsusp-and-swap-files.rst
4754 no Disable hibernation and resume.
4757 during restoration read-only).
4765 AMD-based UNRET and IBPB mitigations alone do not stop
4767 sibling threads. For that reason, STIBP is used on pro-
4771 off - no mitigation
4772 auto - automatically select a migitation
4773 auto,nosmt - automatically select a mitigation,
4777 ibpb - On AMD, mitigate short speculation
4782 ibpb,nosmt - Like "ibpb" above but will disable SMT
4786 unret - Force enable untrained return thunks,
4787 only effective on AMD f15h-f17h based
4789 unret,nosmt - Like unret, but will disable SMT when STIBP
4813 ring3mwait=disable
4814 [KNL] Disable ring 3 MONITOR/MWAIT feature on supported
4817 ro [KNL] Mount root device read-only on boot
4820 on Mark read-only kernel memory as read-only (default).
4821 off Leave read-only kernel memory writable for debugging.
4826 debug-uart get routed to the D+ and D- pins of the usb
4848 rw [KNL] Mount root device read-write on boot
4866 schedstats= [KNL,X86] Enable or disable scheduled statistics.
4867 Allowed values are enable and disable. This feature
4890 to 10 seconds for built-in smp_call_function()
4897 that requesting even small non-zero numbers of
4898 seconds can result in RCU CPU stall warnings,
4904 The default of -1 specifies a number of kthreads
4909 test before initiating CPU-hotplug operations.
4913 CPU-hotplug operations. Specifying zero (which
4914 is the default) disables CPU-hotplug operations.
4920 Non-zero values are useful for automated tests.
4933 preempt_disable() to disable CPU hotplug
4943 "wait" parameter. A value of -1 selects the
4944 default if all other weights are -1. However,
4946 value of -1 will instead select a weight of zero.
4951 non-zero "wait" parameter. See weight_single.
4958 this weighting can place serious IPI load
4964 non-zero "wait" parameter. See weight_single
4976 non-zero "wait" parameter. See weight_single
4983 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
4984 1 -- enable.
4992 selinux= [SELINUX] Disable or enable SELinux at boot time.
4995 0 -- disable.
4996 1 -- enable.
4999 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
5002 0 -- disable.
5003 1 -- enable.
5006 serialnumber [BUGS=X86-32]
5011 simeth= [IA-64]
5017 Disable merging of slabs with similar size. May be
5021 layout control by attackers can usually be
5025 unchanged). Debug options disable merging on their
5038 slub_debug can create guard zones around objects and
5045 memory cgroup sub-caches. 1 to enable, 0 to disable.
5047 Enabling this can lead to a very high number of debug
5078 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
5079 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
5080 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
5081 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
5082 smsc-ircc2.ircc_irq= [HW] IRQ line
5083 smsc-ircc2.ircc_dma= [HW] DMA channel
5084 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
5094 Default: -1 (no limit)
5097 [KNL] Should the soft-lockup detector generate panics.
5100 A value of 1 instructs the soft-lockup detector
5101 to panic the machine when a soft-lockup occurs. It is
5104 respective build-time switch to that functionality.
5107 [KNL] Should the soft-lockup detector generate
5112 See Documentation/admin-guide/laptops/sonypi.rst
5119 on - unconditionally enable, implies
5121 off - unconditionally disable, implies
5123 auto - kernel detects whether your CPU model is
5135 Selecting 'off' will disable both the kernel and
5138 Specific mitigations can also be selected manually:
5140 retpoline - replace indirect branches
5141 retpoline,generic - Retpolines
5142 retpoline,lfence - LFENCE; indirect branch
5143 retpoline,amd - alias for retpoline,lfence
5144 eibrs - enhanced IBRS
5145 eibrs,retpoline - enhanced IBRS + Retpolines
5146 eibrs,lfence - enhanced IBRS + LFENCE
5147 ibrs - use IBRS to protect kernel
5157 on - Unconditionally enable mitigations. Is
5160 off - Unconditionally disable mitigations. Is
5163 prctl - Indirect branch speculation is enabled,
5164 but mitigation can be enabled via prctl
5169 - Like "prctl" above, but only STIBP is
5175 - Same as "prctl" above, but all seccomp
5180 - Like "seccomp" above, but only STIBP is
5185 auto - Kernel selects the mitigation depending on
5195 [HW] Control Speculative Store Bypass (SSB) Disable mitigation
5203 is that such stores are unlikely and that they can
5208 store can be used in a cache side channel attack, for
5217 on - Unconditionally disable Speculative Store Bypass
5218 off - Unconditionally enable Speculative Store Bypass
5219 auto - Kernel detects whether the CPU model contains an
5225 prctl - Control Speculative Store Bypass per thread
5229 seccomp - Same as "prctl" above, but all seccomp threads
5230 will disable SSB unless they explicitly opt out.
5237 on,auto - On Power8 and Power9 insert a store-forwarding
5241 off - No action.
5258 off - not enabled
5260 warn - the kernel will emit rate limited warnings
5265 fatal - the kernel will send SIGBUS to applications
5277 Certain CPUs are vulnerable to an MDS-like
5278 exploit which can leak bits from the random
5282 microcode. However, the microcode fix can cause
5287 The microcode mitigation can be disabled with
5290 off: Disable mitigation and remove
5295 grace-period sequence counter wrap for the
5296 srcu_data structure's ->srcu_gp_seq_needed field.
5307 expediting. Set to zero to disable automatic
5311 Speculative Store Bypass Disable control
5318 force-on: Unconditionally enable mitigation for
5320 force-off: Unconditionally disable mitigation for
5336 disable the stack depot thereby saving the static memory
5343 stacktrace_filter=[function-list]
5345 will trace at boot up. function-list is a comma separated
5346 list of functions. This list can be changed at run
5353 Set the STI (builtin display/keyboard on the HP-PARISC
5355 as the initial boot-console.
5396 to global on non-NUMA machines)
5402 RPC calls that can be sent from the client to a
5421 controller if no parameter or 1 is given or disable
5422 it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)
5424 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
5426 <int> -- Number of I/O TLB slabs
5427 force -- force using of bounce buffers even if they
5429 noforce -- Never use bounce buffers (for debugging)
5443 Enable/disable old style sysfs layout for old udev
5453 Ignore sysrq setting - this boot parameter will
5461 cache size. See Documentation/networking/ip-sysctl.rst
5467 Specify "mem" (for Suspend-to-RAM) or "standby" (for
5472 wakeup-capable RTC alarm.
5478 -1: disable all active trip points in all thermal zones
5482 -1: disable all critical trip points in all thermal zones
5486 Set to disable actions on ACPI thermal zone
5490 1: disable ACPI thermal control
5493 -1: disable all passive trip points
5499 <deci-seconds>: poll all this frequency
5521 Prevent the CPU-hotplug component of torturing
5525 Dump the ftrace buffer at torture-test shutdown,
5526 even if there were no errors. This can be a
5529 with rotating-rust storage.
5545 trace_event=[event-list]
5547 to facilitate early boot debugging. The event-list is a
5551 trace_options=[option-list]
5552 [FTRACE] Enable or disable tracer options at boot.
5553 The option-list is a comma delimited list of options
5554 that can be enabled or disabled just as if you were
5582 frequency tracepoints such as irq or sched, can cause
5586 [FTRACE] enable this option to disable tracing when a
5587 warning is hit. This turns off "tracing_on". Tracing can
5595 This option can also be set at run time via the sysctl
5601 Can be used to control the default behavior of the system
5603 See Documentation/admin-guide/mm/transhuge.rst
5606 tsc= Disable clocksource stability checks for TSC.
5611 high-resolution timer mode on older hardware, and in
5614 Used to run time disable IRQ_TIME_ACCOUNTING on any
5616 can add overhead.
5620 [x86] nowatchdog: disable clocksource watchdog. Used
5637 on - Enable TSX on the system. Although there are
5640 several previous speculation-related CVEs, and
5644 off - Disable TSX on the system. (Note that this
5652 auto - Disable TSX if X86_BUG_TAA is present,
5657 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5663 Similar to Micro-architectural Data Sampling (MDS)
5666 exploit against CPU internal buffers which can forward
5671 data can be used in a cache side channel attack, to
5678 full - Enable TAA mitigation on vulnerable CPUs
5681 full,nosmt - Enable TAA mitigation and disable SMT on
5684 vulnerable to cross-thread TAA attacks.
5685 off - Unconditionally disable TAA mitigation
5687 On MDS-affected machines, tsx_async_abort=off can be
5689 are mitigated with the same mechanism so in order to disable
5699 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5705 See also Documentation/input/devices/joystick-parport.rst
5707 udbg-immortal [PPC] When debugging early kernel crashes that
5713 Set number of hash buckets for UDP/UDP-Lite connections
5715 uhci-hcd.ignore_oc=
5717 Some badly-designed motherboards generate lots of
5728 (default -1 = authorized except for wireless USB,
5734 for newly-detected USB devices (default 2). This
5762 [USB] Specifies timeout for the initial 64-byte
5766 usbcore.nousb [USB] Disable the USB subsystem
5769 [USB] A list of quirk entries to augment the built-in
5772 VendorID:ProductID:Flags. The IDs are 4-digit hex
5774 will change the built-in quirk; setting it if it is
5779 a 255-byte read);
5780 b = USB_QUIRK_RESET_RESUME (device can't resume
5782 c = USB_QUIRK_NO_SET_INTF (device can't handle
5783 Set-Interface requests);
5784 d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't
5787 e = USB_QUIRK_RESET (device can't be reset
5791 bNumInterfaces count, and can't handle
5802 (bInterval-1).
5807 i = USB_QUIRK_DEVICE_QUALIFIER (device can't
5813 k = USB_QUIRK_NO_LPM (device can't handle Link
5837 usb-storage.delay_use=
5841 usb-storage.quirks=
5843 override the built-in unusual_devs list. List
5846 and Product ID values (4-digit hex numbers) and
5848 to a common usb-storage quirk flag as follows:
5890 medium is write-protected).
5899 1 - undefined instruction events
5900 2 - system calls
5901 4 - invalid data aborts
5902 8 - SIGSEGV faults
5903 16 - SIGBUS faults
5917 vdso=0: disable VDSO mapping
5919 vdso32= [X86] Control the 32-bit vDSO
5920 vdso32=1: enable 32-bit VDSO
5921 vdso32=0 or vdso32=2: disable 32-bit VDSO
5931 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
5933 vector= [IA-64,SMP]
5953 <size> := size (can use standard suffixes
5962 Can be used multiple times for multiple devices.
5964 vga= [BOOT,X86-32] Select a particular video mode
5966 Documentation/admin-guide/svga.rst.
5981 - Disable all of the above options
5984 size of <nn>. This can be used to increase the
5985 minimum size (128MB on x86). It can also be used to
6002 vsyscall= [X86-64]
6005 code). Most statically-linked binaries and older
6008 targets for exploits that can control RIP.
6029 see VGA-softcursor.txt. Default: 2 = underline.
6034 This is a 16-member array composed of values
6035 ranging from 0-255.
6040 This is a 16-member array composed of values
6041 ranging from 0-255.
6046 This is a 16-member array composed of values
6047 ranging from 0-255.
6052 Set system-wide default UTF-8 mode for all tty's.
6053 Default is 1, i.e. UTF-8 mode is enabled for all
6058 Format=<-1|0|1>
6059 Set system-wide default for whether a cursor
6060 is shown on new VTs. Default is -1,
6065 vt.italic= [VT] Default color for italic text; 0-15.
6068 vt.underline= [VT] Default color for underlined text; 0-15.
6072 see Documentation/watchdog/watchdog-parameters.rst
6073 or other driver-specific files in the
6085 If CONFIG_WQ_WATCHDOG is configured, workqueue can
6090 it can be updated at runtime by writing to the
6098 whatever reason, this option can be used. Note
6099 that this also can be controlled per-workqueue for
6103 Per-cpu workqueues are generally preferred because
6105 locality; unfortunately, per-cpu workqueues tend to
6108 Enabling this makes the per-cpu workqueues which
6123 forces round-robin CPU selection to flush out
6128 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
6132 x86_intel_mid_timer= [X86-32,APBT]
6138 xen_512gb_limit [KNL,X86-64,XEN]
6148 ide-disks -- unplug primary master IDE devices
6149 aux-ide-disks -- unplug non-primary-master IDE devices
6150 nics -- unplug network devices
6151 all -- unplug all emulated devices (NICs and IDE disks)
6152 unnecessary -- unplugging emulated devices is
6155 never -- do not unplug even if version check succeeds
6173 [KNL,X86,XEN] Disable the vector callback for Xen
6178 to Xen, for use by other domains. Can be also changed at runtime
6182 xen_timer_slop= [X86-64,XEN]
6205 Boolean parameter to disable using fifo event handling
6207 preferred over the 2-level event handling, as it is
6234 xhci-hcd.quirks [USB,KNL]
6236 host controller quirks. Meaning of each bit can be
6252 can be written using xmon commands.
6254 memory, and other data can't be written using