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
79 can interfere with legacy drivers.
111 by unsupported hardware/firmware features can result in
114 This facility can be used to prevent such uncontrolled
116 Format: <byte> or <bitmap-list>
119 Disable auto-serialization of AML methods
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
161 acpi_osi=! # disable all built-in OS vendor
163 acpi_osi=!! # enable all built-in OS vendor
165 acpi_osi= # disable all strings
167 'acpi_osi=!' can be used in combination with single or
169 vendor string(s). Note that such command can only
180 can make '_OSI("Windows 2000")' TRUE.
184 exist in the ACPI namespace. NOTE that such command can
189 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
192 'acpi_osi=!*' can be used in combination with single or
194 string(s). Note that such command can affect the
204 1. 'acpi_osi="Module Device" acpi_osi=!*' can make
206 2. 'acpi_osi=!* acpi_osi="Module Device"' can make
225 For broken nForce2 BIOS resulting in XT-PIC timer.
233 as soon as the kernel's real-mode entry point is called.
258 off: disable AGP support
263 See Documentation/sound/alsa-configuration.rst
270 align_va_addr= [X86-64]
275 CPU-intensive style benchmark, and it can vary highly in
278 32: only for 32-bit processes
279 64: only for 64-bit processes
280 on: enable for both 32- and 64-bit processes
281 off: disable for both 32- and 64-bit processes
291 Allow execve() of 32-bit applications and setting of the
293 subset of the CPUs support 32-bit EL0. When this
294 parameter is present, the set of CPUs supporting 32-bit
296 and hot-unplug operations may be restricted.
298 See Documentation/arm64/asymmetric-32bit.rst for more
301 amd_iommu= [HW,X86-64]
304 fullflush - Deprecated, equivalent to iommu.strict=1
305 off - do not initialize any AMD IOMMU found in
307 force_isolation - Force device isolation for all
312 force_enable - Force enable the IOMMU on platforms known
316 amd_iommu_dump= [HW,X86-64]
322 amd_iommu_intr= [HW,X86-64]
325 legacy - Use legacy interrupt remapping mode.
326 vapic - Use virtual APIC mode, which allows IOMMU
328 This mode requires kvm-amd.avic=1.
342 Power management functions (SPARCstation-4/5 + deriv.)
344 Disable APC CPU standby support. SPARCstation-Fox does
345 not play well with APC CPU idle - disable it if you have
352 when initialising the APIC and IO-APIC components.
353 For X86-32, this can also be used to specify an APIC
373 to set it to "all" by meaning -- no limit here.
382 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
385 arm64.nobti [ARM64] Unconditionally disable Branch Target
388 arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication
391 arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension
415 audit= [KNL] Enable the audit sub-system
417 0 | off - kernel audit is disabled and can not be
419 unset - kernel audit is initialized but disabled and
421 1 | on - kernel audit is initialized and partially
432 behavior is to disable the BAU (i.e. bau=0).
434 0 - Disable the BAU.
435 1 - Enable the BAU.
436 unset - Disable the BAU.
457 See Documentation/block/cmdline-partition.rst
465 Extended command line options can be added to an initrd
468 See Documentation/admin-guide/bootconfig.rst
471 Disable BERT OS support on buggy BIOSes.
474 Disable BGRT to avoid flickering OEM logo.
479 bttv.pll= See Documentation/admin-guide/media/bttv.rst
488 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
507 inclusive. See arch/mips/include/asm/pgtable-bits.h
514 cgroup_disable= [KNL] Disable a particular controller or optional feature
515 Format: {name of the controller(s) or feature(s) to disable}
517 - foo isn't auto-mounted if you mount all cgroups in
519 - foo isn't visible as an individually mountable
521 - if foo is an optional feature then the feature is
525 cut the overhead, others just disable the usage. So
527 Specifying "pressure" disables per-cgroup pressure
530 cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1
541 nosocket -- Disable socket memory accounting.
542 nokmem -- Disable kernel memory accounting.
547 0 -- check protection applied by kernel (includes
549 1 -- check protection requested by application.
551 Value can be changed at runtime via
563 force such clocks to be always-on nor does it reserve
567 information, see Documentation/driver-api/clk.rst.
569 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
586 [X86-32] pit,hpet,tsc;
593 [X86-64] hpet,tsc
598 Enable/disable the eventstream feature of the ARM
599 architected timer so that code using WFE-based polling
600 loops can be debugged more effectively on production
619 clocksource-wdtest.holdoff= [KNL]
626 Disable CPUID feature X for the kernel. See
635 Also note the kernel might malfunction if you disable
638 cma=nn[MG]@[start[MG][-end[MG]]]
649 Sets the size of kernel per-numa memory area for
651 per-numa CMA altogether. And If this option is not
653 With per-numa CMA enabled, DMA users on node nid will
669 com20020= [HW,NET] ARCnet - COM20020 chipset
673 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
677 ARCnet - COM90xx chipset (memory-mapped buffers)
695 See Documentation/admin-guide/serial-console.rst for more
705 Start an early, polled-mode console on the 8250/16550
708 MMIO inter-register address stride is either 8-bit
709 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
713 the h/w is not re-initialized.
734 syscall, or to executing "dmesg -S --raw" or to reading
749 Enable/disable the CPU sampling based debugging.
750 0: default value, disable debugging
754 disable the cpuidle sub-system
760 disable the cpufreq sub-system
768 [X86] Delay for N microsec between assert and de-assert
778 [KNL] Using kexec, Linux can switch to a 'crash kernel'
783 [KNL, X86-64] Select a region under 4G first, and
786 See Documentation/admin-guide/kdump/kdump.rst for further details.
791 start-[end] where start and end are both
793 Documentation/admin-guide/kdump/kdump.rst for an example.
796 [KNL, X86-64] range could be above 4G. Allow kernel
803 [KNL, X86-64] range under 4G. When crashkernel=X,high
808 low memory is needed to make sure DMA buffers for 32-bit
813 0: to disable low allocation.
818 [KNL] Disable crypto self-tests
826 csdlock_debug= [KNL] Enable debug add-ons of cross-CPU function call
831 0: disable csdlock debugging (default)
842 See also Documentation/input/devices/joystick-parport.rst
846 Documentation/admin-guide/dynamic-debug-howto.rst for
860 [KNL] verbose locking self-tests
863 self-tests.
865 (no extra messages), setting it to -1 (all bits set)
866 will print _a_lot_ more information - normally only
872 [KNL] Disable object debugging
904 Format: { on, no-mount, off }
906 no-mount:
907 Filesystem is not registered but kernel clients can
908 access APIs and a crashkernel can be used to read
911 get a -EPERM as result when trying to register files
915 Default value is set in build-time with a kernel configuration.
931 Documentation/admin-guide/mm/hugetlbpage.rst.
961 can be useful when debugging issues that require an SLB
969 disable= [IPV6]
978 against bounds-checking flaws in the kernel's
981 off Disable hardened usercopy checks.
984 Disable RADIX MMU mode on POWER9
987 Disable RADIX GTSE feature and use hcall for TLB
991 Disable TLBIE instruction. Currently does not work
999 disable BSP to wake up multiple CPUs without
1004 Disable Dynamic DMA Window support. Use this
1022 Disable PIN 1 of APIC timer
1023 Can be useful to work around chipset bugs.
1025 dis_ucode_ldr [X86] Disable the microcode loader.
1032 entries for DMA-API debugging code. One entry is
1033 required per DMA-API allocation. Use this if the
1034 DMA-API debugging code disables itself because the
1038 With this option the DMA-API debugging driver
1039 filter feature can be enabled at boot time. Just
1041 The filter can be disabled or changed to another
1053 Generic built-in EDID data sets are used, if one of
1058 available in Documentation/admin-guide/edid.rst. An EDID
1070 Control how the dt_cpu_ftrs device-tree binding is
1080 what data is available or for reverse-engineering.
1085 Documentation/admin-guide/dynamic-debug-howto.rst
1088 nopku [X86] Disable Memory Protection Keys CPU feature found
1102 determined by stdout-path property in device tree's
1107 Start an early, polled-mode console on a Cadence
1118 Start an early, polled-mode console on the 8250/16550
1120 MMIO inter-register address stride is either 8-bit
1121 (mmio) or 32-bit (mmio32 or mmio32be).
1129 Start an early, polled-mode console on a pl011 serial
1133 the driver will use only 32-bit accessors to read/write
1142 Start an early, polled-mode console on a meson serial
1148 Start an early, polled-mode console on an msm serial
1154 Start an early, polled-mode console on an msm serial
1160 Start an early, polled-mode console on a serial port
1166 Start an early, polled-mode console on a serial port
1172 Use RISC-V SBI (Supervisor Binary Interface) for early
1190 Start an early, polled-mode console on a lantiq serial
1204 Start an early, polled-mode, output-only console on the
1209 Start an early, polled-mode console on the
1215 Start an early, polled-mode console on a Qualcomm
1223 coherent non-x86 systems that use system memory for
1248 Append ",keep" to not disable it when the real console
1251 Only one of vga, efi, serial, or usb debug port can
1259 You can find the port for a given device in
1269 The xen option can only be used in Xen domains.
1271 The sclp output can only be used on s390.
1281 off: disable H/W event reporting through EDAC.
1292 but can only be used if the backing tty is available
1304 disable_early_pci_dma: disable the busmaster bit on all
1306 nochunk: disable reading files in "chunks" in the EFI
1307 boot stub, as chunking can cause problems with some
1309 noruntime : disable EFI runtime services support
1313 claim. Specify efi=nosoftreserve to disable this
1321 Using this parameter you can use more than 50% of
1334 attribute is added to range 0x100000000-0x180000000 and
1335 0x10a0000000-0x1120000000.
1339 range 0x240000000-0x43fffffff.
1341 Using this parameter you can do debugging of EFI memmap
1342 related features. For example, you can do debugging of
1351 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1357 elanfreq= [X86-32]
1365 See Documentation/admin-guide/kdump/kdump.rst for details.
1374 Can be useful to work around chipset bugs
1381 0 -- permissive (log only, no denials).
1382 1 -- enforcing (deny and log).
1384 Value can be changed at runtime via
1388 Disable Error Record Serialization Table (ERST)
1406 See also Documentation/fault-injection/.
1410 See Documentation/admin-guide/sysctl/net.rst for
1414 See Documentation/admin-guide/blockdev/floppy.rst.
1417 [IA-64] Avoid check_sal_cache_flush which may hang on
1422 forcepae [X86-32]
1424 Many Pentium M systems disable PAE but may have a
1441 ftrace_filter=[function-list]
1443 tracer at boot up. function-list is a comma-separated
1444 list of functions. This list can be changed at run
1448 ftrace_notrace=[function-list]
1450 function-list. This list can be changed at run time
1454 ftrace_graph_filter=[function-list]
1457 function-list is a comma-separated list of functions
1458 that can be changed at run time by the
1461 ftrace_graph_notrace=[function-list]
1463 function-list. This list is a comma-separated list of
1464 functions that can be changed at run time by the
1470 can be changed at run time by the max_graph_depth file
1483 off -- Don't create device links from firmware info.
1484 permissive -- Create device links from firmware info
1487 on -- Create device links from firmware info and use it
1489 rpm -- Like "on", but also use to order runtime PM.
1500 See also Documentation/input/devices/joystick-parport.rst
1504 gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
1508 gcov_persist= [GCOV] When non-zero (default), profiling data for
1518 gpio-mockup.gpio_mockup_ranges
1521 gpio-mockup.gpio_mockup_named_lines
1548 [KNL] Should the hard-lockup detector generate
1554 for 64-bit NUMA, off otherwise.
1557 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1563 Disable Hardware Error Source Table (HEST) support;
1564 corresponding firmware-first mode error processing
1572 highres= [KNL] Enable/disable high resolution timer mode.
1578 hpet= [X86-32,HPET] option to control HPET usage
1579 Format: { enable (default) | disable | force |
1581 disable: disable HPET and use PIT instead
1595 boot-time allocation of gigantic hugepages is skipped.
1603 Documentation/admin-guide/mm/hugetlbpage.rst.
1610 hugepagesz=X hugepages=Y can be specified once for
1613 Documentation/admin-guide/mm/hugetlbpage.rst.
1624 off: disable the feature
1639 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1640 option. The value selected by this boot parameter can
1645 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1668 (disabled by default, and as a pre-condition
1670 i8042.direct [HW] Put keyboard port into non-translated mode
1671 i8042.dumbkbd [HW] Pretend that controller can only read data from
1676 i8042.noloop [HW] Disable the AUX Loopback command while probing
1684 suspend-to-ram transitions, only during s2r
1717 -1 -- never invert brightness
1718 0 -- machine default
1719 1 -- force brightness inversion
1724 ide-core.nodma= [HW] (E)IDE subsystem
1730 ide-generic.probe-mask= [HW] (E)IDE subsystem
1742 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1747 Poll forces a polling idle loop that can slightly
1753 idle=nomwait: Disable mwait for CPU C-states
1781 legacy only accept legacy-NaN binaries, if supported
1783 2008 only accept 2008-NaN binaries, if supported
1792 'relaxed' straps the emulator for both legacy-NaN and
1793 2008-NaN, whereas 'strict' enables legacy-NaN only on
1802 Ignore loglevel setting - this will print /all/
1810 print warning at first misuse. Can be changed via
1869 Formats: { "ima" | "ima-ng" | "ima-sig" }
1870 Default: "ima-ng"
1882 different crypto accelerators. This option can be used
1890 different crypto accelerators. This option can be used
1902 initcall_blacklist= [KNL] Do not execute a comma-separated list of
1903 initcall functions. Useful for debugging built-in
1913 but as a debugging aid, one can get the
1938 default (disallow access to all but pkey 0). Can
1948 0 -- basic integrity auditing messages. (Default)
1949 1 -- additional integrity auditing messages.
1955 Disable intel iommu driver.
1977 could harm performance of some high-throughput
1986 1 to 9 specify maximum depth of C-state.
1989 disable
1996 used along with the hardware-managed P-states (HWP)
2000 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2001 instead of acpi-cpufreq may disable platform features, such
2003 P-States information being indicated to OSPM and therefore
2006 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2019 Allow per-logical-CPU P-State performance control limits using
2022 intremap= [X86-64, Intel-IOMMU]
2024 off disable Interrupt Remapping
2025 nosid disable Source ID checking
2027 BIOS x2APIC opt-out request will be ignored
2028 nopost disable Interrupt Posting
2030 iomem= Disable strict checking of access to MMIO memory
2047 Disable IOMMU bypass, using IOMMU for PCI devices.
2051 0 - Try to allocate a 32-bit DMA address first, before
2053 1 - Allocate directly from the full usable range,
2055 greater than 32-bit addressing.
2059 0 - Lazy mode.
2065 1 - Strict mode.
2068 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2070 legacy driver-specific options takes precedence.
2075 0 - Use IOMMU translation for DMA.
2076 1 - Bypass the IOMMU for DMA.
2077 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2079 io7= [HW] IO7 for Marvel-based Alpha systems
2094 See Documentation/admin-guide/nfs/nfsroot.rst.
2118 Enables support for pseudo-NMIs in the kernel. This
2137 [Deprecated - use cpusets instead]
2138 Format: [flag-list,]<cpu-list>
2144 Disable the tick when a single task runs.
2161 advised to use cpusets instead to disable scheduler load
2163 It offers a much more flexible interface where CPUs can
2166 You can move a process onto or off an "isolated" CPU via
2169 "number of CPUs in system - 1".
2195 The format of <cpu-list> is described above.
2199 ivrs_ioapic [HW,X86-64]
2200 Provide an override to the IOAPIC-ID<->DEVICE-ID
2202 example, to map IOAPIC-ID decimal 10 to
2206 ivrs_hpet [HW,X86-64]
2207 Provide an override to the HPET-ID<->DEVICE-ID
2209 example, to map HPET-ID decimal 0 to
2213 ivrs_acpihid [HW,X86-64]
2214 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2216 example, to map UART-HID:UID AMD0020:0 to
2236 kernelcore= [KNL,X86,IA-64,PPC]
2239 the kernel for non-movable allocations. The requested
2249 subsystem. Note that allocations like PTEs-from-HighMem
2257 for non-movable allocations and remaining memory is used
2268 gdb or control-c on the dbgp connection. When
2269 not using this parameter you use sysrq-g to break into
2274 or a supported polling keyboard driver (non-usb).
2284 characters and can work in polling mode, you can use
2301 Configure the RouterBoard 532 series on-chip
2304 kmemleak= [KNL] Boot-time kmemleak enable/disable
2310 kprobe_event=[probe-list]
2312 The probe-list is a semicolon delimited list of probe
2358 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
2361 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
2363 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
2365 kvm-arm.mode=
2368 nvhe: Standard nVHE-based mode, without support for
2371 protected: nVHE-based mode with support for guests whose
2377 kvm-arm.vgic_v3_group0_trap=
2378 [KVM,ARM] Trap guest accesses to GICv3 group-0
2381 kvm-arm.vgic_v3_group1_trap=
2382 [KVM,ARM] Trap guest accesses to GICv3 group-1
2385 kvm-arm.vgic_v3_common_trap=
2389 kvm-arm.vgic_v4_enable=
2401 kvm-intel.ept= [KVM,Intel] Disable extended page tables
2405 kvm-intel.emulate_invalid_guest_state=
2409 kvm-intel.flexpriority=
2410 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
2413 kvm-intel.nested=
2417 kvm-intel.unrestricted_guest=
2418 [KVM,Intel] Disable unrestricted guest feature
2422 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2423 CVE-2018-3620.
2429 VMEXIT and VMENTER can leak host memory.
2434 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
2442 internal buffers which can forward information to a
2446 forwarded data can be used in a cache side channel
2453 on - enable the interface for the mitigation
2518 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2524 lapic [X86-32,APIC] Enable the local APIC even if BIOS
2528 value for LAPIC timer one-shot implementation. Default
2536 libata.dma=0 Disable all PATA and SATA DMA
2551 libata.force= [LIBATA] Force configurations. The format is comma-
2563 first fan-out link behind PMP device. It does not
2570 The following configurations can be forced.
2577 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2589 hot-unplug link recovery
2595 * disable: Disable this device.
2626 Set the number of locking read-acquisition kthreads.
2631 Set the number of locking write-acquisition kthreads.
2634 Set time (s) after boot for CPU-hotplug testing.
2637 Set time (s) between CPU-hotplug operations, or
2638 zero to disable CPU-hotplug testing.
2641 Set task-shuffle interval (jiffies). Shuffling
2642 tasks allows some CPUs to go into dyntick-idle
2647 is useful for hands-off automated testing.
2669 console loglevel will be printed to the console. It can
2680 7 (KERN_DEBUG) debug-level messages
2690 logo.nologo [FB] Disables display of the built-in Linux logo.
2698 lp=auto printer driver. 'lp=reset' (which can be
2708 an IEEE 1284-compliant printer is attached; if
2714 time-consuming boot-time autodetection (up to 250 ms per
2735 machvec= [IA-64] Force the use of a particular machine-vector
2741 Example: machtype=lemote-yeeloong-2f-7inch
2749 bootup you can bring up the other plugged cpu by executing
2756 (loop.max_loop) unconditionally pre-created at init time. The default
2759 devices can be requested on-demand with the
2760 /dev/loop-control interface.
2762 mce [X86-32] Machine Check Exception
2764 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.rst
2767 See Documentation/admin-guide/md.rst.
2774 Control mitigation for the Micro-architectural Data
2778 internal buffers which can forward information to a
2782 forwarded data can be used in a cache side channel
2789 full - Enable MDS mitigation on vulnerable CPUs
2790 full,nosmt - Enable MDS mitigation and disable
2792 off - Unconditionally disable MDS mitigation
2794 On TAA-affected machines, mds=off can be prevented by
2796 mitigated with the same mechanism so in order to disable
2803 For details see: Documentation/admin-guide/hw-vuln/mds.rst
2822 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
2827 per-device physically contiguous DMA buffers.
2835 See Documentation/admin-guide/mm/memory-hotplug.rst.
2839 Such memmap=exactmap lines can be constructed based on
2848 Multiple different regions can be specified,
2860 Example: Exclude memory from 0x18690000-0x1869ffff
2874 memmap=<size>%<offset>-<oldtype>+<newtype>
2876 from <oldtype> to <newtype>. If "-<oldtype>" is left
2891 repeatable BIOS-originated corruption always
2892 affects the same memory, you can use memmap=
2918 The state of the flag can be read in
2929 default : 0 <disable>
2937 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
2945 Refer to Documentation/virt/kvm/amd-memory-encryption.rst
2946 for details on when memory encryption can be activated.
2949 s2idle - Suspend-To-Idle
2950 shallow - Power-On Suspend or equivalent (if supported)
2951 deep - Suspend-To-RAM or equivalent (if supported)
2952 See Documentation/admin-guide/pm/sleep-states.rst.
2955 See Documentation/admin-guide/media/meye.rst.
2957 mfgpt_irq= [IA-32] Specify the IRQ to use for the
2958 Multi-Function General Purpose Timers on AMD Geode
2961 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
2964 problem by letting the user disable the workaround.
2975 0 - The attached screen is the 3.5" TFT
2976 1 - The attached screen is the 7" TFT
2977 2 - The VGA Shield is attached (1024x768)
2981 b - Enable backlight. The TFT backlight pin will be
2985 c - Enable the s3c camera interface.
2986 t - Reserved for enabling touchscreen support. The
2988 kernel as of 2.6.30, a preliminary port can be found
2990 https://repo.or.cz/w/linux-2.6/mini2440.git
2995 arch-independent options, each of which is an
2996 aggregation of existing arch-specific options.
2999 Disable all optional CPU mitigations. This
3009 ssbd=force-off [ARM64]
3027 have other ways of avoiding SMT-based attacks.
3052 module_blacklist= [KNL] Do not load a comma-separated list of
3066 movablecore= [KNL,X86,IA-64,PPC]
3077 movable_node [KNL] Boot-time switch to make hotplugable memory
3084 Format: <name>,<region-number>,<size>,<offset>
3087 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3096 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
3100 boundary - index of last SLC block on Flex-OneNAND.
3102 lock - Configure if Flex-OneNAND boundary should be locked.
3109 See arch/arm/mach-s3c/mach-jive.c
3137 something different and driver-specific.
3143 0 to disable accounting
3148 See Documentation/admin-guide/nfs/nfsroot.rst.
3150 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3151 See Documentation/admin-guide/nfs/nfsroot.rst.
3154 See Documentation/admin-guide/nfs/nfsroot.rst.
3178 [NFS] enable 64-bit inode numbers.
3179 If zero, the NFS client will fake up a 32-bit inode
3181 of returning the full 64-bit number.
3182 The default is to return 64-bit inode numbers.
3195 that the client can send to the NFSv4.1 server.
3205 disabling idmapping, which can make migration from
3212 [NFS4] Specify an additional fixed unique ident-
3213 ification string that NFSv4 clients can insert into
3243 driver. A non-zero value sets the minimum interval
3255 NMI stack-backtrace request.
3264 0 - turn hardlockup detector in nmi_watchdog off
3265 1 - turn hardlockup detector in nmi_watchdog on
3269 To disable both hard and soft lockup detectors,
3274 These settings can be accessed at runtime via
3282 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3286 no5lvl [X86-64] Disable 5-level paging mode. Forces
3287 kernel to use 4-level paging instead.
3293 Disable suspending of consoles during suspend and
3295 messages can reach various consoles while the rest
3307 Disable device dump. Device dump allows drivers to
3308 append dump data to vmcore so you can collect driver
3309 specified debug info. Drivers can append the data
3312 device dump can help save memory but the driver debug
3318 caches in the slab allocator. Saves per-node memory,
3329 noautogroup Disable scheduler automatic task group creation.
3338 delayacct [KNL] Enable per-task delay accounting
3340 nodsp [SH] Disable hardware DSP at boot time.
3342 noefi Disable EFI runtime services support.
3344 no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel.
3346 noexec [IA-64]
3349 On X86-32 available only on PAE configured kernels.
3350 noexec=on: enable non-executable mappings (default)
3351 noexec=off: disable non-executable mappings
3354 Disable SMAP (Supervisor Mode Access Prevention)
3358 Disable SMEP (Supervisor Mode Execution Prevention)
3361 noexec32 [X86-64]
3362 This affects only 32-bit executables.
3363 noexec32=on: enable non-executable mappings (default)
3365 noexec32=off: disable non-executable mappings
3368 nofpu [MIPS,SH] Disable hardware FPU at boot time.
3370 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3372 legacy floating-point registers on task switch.
3374 nohugeiomap [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.
3376 nohugevmalloc [PPC] Disable kernel huge vmalloc mappings.
3378 nosmt [KNL,S390] Disable symmetric multithreading (SMT).
3381 [KNL,X86] Disable symmetric multithreading (SMT).
3382 nosmt=force: Force disable SMT, cannot be undone
3385 nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1
3389 nospectre_v2 [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for
3395 [HW] Disable all mitigations for the Speculative Store Bypass vulnerability
3398 [PPC] Don't flush the L1-D cache after accessing user data.
3402 enabling legacy floating-point and sse state.
3432 nohalt [IA-64] Tells the kernel not to use the power saving
3434 power-consumption. On the positive side, it reduces
3435 interrupt wake-up latency, which may improve performance
3437 real-time systems.
3446 difficult since unequal pointers can no longer be
3447 compared. However, if this command-line option is
3454 nohibernate [HIBERNATION] Disable hibernation and resume.
3456 nohz= [KNL] Boottime enable/disable dynamic ticks
3472 noirqdebug [X86-32] Disables the code which attempts to detect and
3473 disable unhandled interrupt sources.
3483 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
3485 [Deprecated - use intremap=off]
3487 nointroute [IA-64]
3489 noinvpcid [X86] Disable the INVPCID cpu feature.
3491 nojitter [IA-64] Disables jitter checking for ITC timers.
3493 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
3495 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
3498 no-vmw-sched-clock
3499 [X86,PV_OPS] Disable paravirtualized VMware scheduler
3502 no-steal-acc [X86,PV_OPS,ARM64] Disable paravirtualized steal time
3506 nolapic [X86-32,APIC] Do not enable or use the local APIC.
3508 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
3513 nomca [IA-64] Disable machine check abort handling
3515 nomce [X86-32] Disable Machine Check Exception
3517 nomfgpt [X86-32] Disable Multi-Function General Purpose
3520 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
3524 nomodule Disable module load
3526 nopat [X86] Disable PAT (page attribute table extension of
3529 nopcid [X86-64] Disable the PCID cpu feature.
3534 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
3537 nordrand [X86] Disable kernel use of the RDRAND and
3545 no-scroll [VGA] Disables scrollback.
3546 This is required for the Braillex ib80-piezo Braille
3549 nosbagart [IA-64]
3551 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
3553 nosgx [X86-64,SGX] Disables Intel SGX kernel support.
3556 and disable the IO APIC. legacy for "maxcpus=0".
3558 nosoftlockup [KNL] Disable the soft-lockup detector.
3562 nowatchdog [KNL] Disable both lockup detectors, i.e.
3563 soft-lockup and NMI watchdog (hard-lockup).
3567 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
3575 2. PIC interrupts also depend on CPU0. CPU0 can't be
3580 If the dependencies are under your control, you can
3585 cycles, each HW thread of the CTOP can run
3592 nptcg= [IA-64] Override max number of concurrent global TLB
3600 runtime you can physically add extra cpu until it reaches
3601 n. So during boot up some boot time memory for per-cpu
3602 variables need be pre-allocated for later physical cpu
3607 numa=off [KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only
3610 numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
3612 Allowed values are enable and disable
3615 'node', 'default' can be specified
3616 This can be set from sysctl after boot.
3617 See Documentation/admin-guide/sysctl/vm.rst for details.
3620 See Documentation/core-api/debugging-via-ohci1394.rst for more
3645 running on a platform with a direct-mapped memory-side
3646 cache, and this parameter can be used to
3647 override/disable that behavior. The state of the flag
3648 can be read from sysfs at:
3651 page_owner= [KNL] Boot-time page_owner enabling option.
3654 we can turn it on.
3657 page_poison= [KNL] Boot-time parameter changing the state of
3667 reporting is disabled when it exceeds (MAX_ORDER-1).
3676 User can chose combination of the following bits:
3689 The optional switch "nousertaint" can be utilized to
3693 See Documentation/admin-guide/tainted-kernels.rst for
3694 extra details on the taint flags that users can pick
3701 Run kdump after running panic-notifiers and dumping
3705 because some panic notifiers can make the crashed
3720 possible conflicts). You can specify the base
3739 Set to non-zero to probe primary and secondary ISA
3745 Set to non-zero if a chip is present that snoops speed
3793 Set to non-zero to probe tertiary and further ISA
3802 of individual ports can be disabled by setting the
3809 Set to non-zero to probe QDI controllers. By default
3814 Set to non-zero to probe Winbond controllers. Use
3836 See also Documentation/admin-guide/blockdev/paride.rst.
3855 addresses can be specified after the base
3865 bios [X86-32] force use of PCI BIOS, don't access
3867 has a non-standard PCI host bridge.
3868 nobios [X86-32] disallow use of PCI BIOS, only direct
3874 data in IO port 0xCFC, both 32-bit).
3876 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
3877 the function, IO port 0xCFA, also 8-bit, sets
3879 through ports 0xC000-0xCFFF).
3883 enabled, this kernel boot option can be used to
3884 disable the use of PCIE advanced error reporting.
3885 nodomains [PCI] Disable support for multiple PCI
3886 root domains (aka PCI segments, in ACPI-speak).
3887 nommconf [X86] Disable use of MMCONFIG for PCI
3893 enabled, this kernel boot option can be used to
3894 disable the use of MSI interrupts system-wide.
3895 noioapicquirk [APIC] Disable all boot interrupt quirks.
3899 primary IO-APIC for bridges that cannot disable
3902 noioapicreroute [APIC] Disable workaround that uses the
3906 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
3924 assigned automatically to PCI devices. You can
3930 F0000h-100000h range.
3931 lastbus=N [X86] Scan all buses thru bus #N. Can be
3935 assign-busses [X86] Always assign all PCI bus
3956 skip_isa_align [X86] do not align io start addr, so can
3963 bfsort Sort PCI devices into breadth-first order.
3966 nobfsort Don't sort PCI devices into breadth-first order.
3967 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
3968 tuning and use the BIOS-configured MPS defaults.
3975 or bus can support) for best performance.
3978 configuration allows peer-to-peer DMA between
3981 that hot-added devices will work.
3996 A PCI-PCI bridge can be specified if resource
4002 for 4096-byte alignment.
4003 ecrc= Enable/disable PCIe ECRC (transaction layer
4004 end-to-end CRC checking).
4025 realloc= Enable/disable reallocating PCI bridge resources
4033 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4040 can resize a BAR to allow access to all VRAM.
4058 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
4060 off Disable ASPM.
4069 dpc-native Use native PCIe service for DPC only. May
4071 compat Disable native PCIe services (PME, AER, DPC, PCIe
4075 off Disable power management of all PCIe ports
4086 Keep all power-domains already enabled by bootloader on,
4092 See Documentation/admin-guide/blockdev/paride.rst.
4094 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
4107 See Documentation/admin-guide/blockdev/paride.rst.
4110 See Documentation/admin-guide/blockdev/paride.rst.
4112 pirq= [SMP,APIC] Manual mp-table setup
4113 See Documentation/x86/i386/IO-APIC.rst.
4117 See also Documentation/admin-guide/parport.rst.
4128 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4137 { on | off | curr | res | no-curr | no-res }
4173 Disable Hardware Transactional Memory
4177 none - Limited to cond_resched() calls
4178 voluntary - Limited to cond_resched() and might_sleep() calls
4179 full - Any section that isn't explicitly preempt disabled
4180 can be preempted anytime.
4182 print-fatal-signals=
4188 coredump - etc.
4191 you might want to try "ulimit -i unlimited".
4198 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4202 Disable console loglevel raise on oops, panic
4203 or lockdep-detected issues (only if lock debug is on).
4212 on - unlimited logging to /dev/kmsg from userspace
4213 off - logging to /dev/kmsg disabled
4214 ratelimit - ratelimit the logging
4218 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4221 Limit processor to maximum C-state
4225 Ignore the _CST method to determine C-states,
4232 Param: "schedule" - profile schedule points.
4233 Param: "sleep" - profile D-state sleeping (millisecs).
4235 Param: "kvm" - profile VM exits.
4236 Param: <number> - step/bucket size as a power of 2 for
4246 psi= [KNL] Enable or disable pressure stall information
4266 See Documentation/admin-guide/blockdev/paride.rst.
4268 pti= [X86-64] Control Page Table Isolation of user and
4273 on - unconditionally enable
4274 off - unconditionally disable
4275 auto - kernel detects whether your CPU model is
4280 nopti [X86-64]
4284 [KNL] Number of legacy pty's. Overwrites compiled-in
4287 quiet [KNL] Disable most log messages
4292 See Documentation/admin-guide/md.rst.
4295 See Documentation/admin-guide/blockdev/ramdisk.rst.
4300 [KNL] Enable or disable trusting the use of the
4306 [KNL] Enable or disable kernel stack offset
4310 cross-syscall address exposures. This is only
4313 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4316 ras=option[,option,...] [KNL] RAS-specific options
4319 Disable the Correctable Errors Collector,
4326 the specified list of CPUs to be no-callback CPUs.
4329 purpose, where "x" is "p" for RCU-preempt, and
4330 "s" for RCU-sched, and "N" is the CPU number.
4332 which can be useful for HPC and real-time
4333 workloads. It can also improve energy efficiency
4341 This improves the real-time response for the
4358 RCU grace-period cleanup.
4362 RCU grace-period initialization.
4366 RCU grace-period pre-initialization, that is,
4367 the propagation of recent CPU-hotplug changes up
4372 per-CPU rcuc kthreads. Defaults to a non-zero
4376 But note that CONFIG_PREEMPT_RT=y kernels disable
4381 Disable autobalancing of the rcu_node combining
4384 cache-to-cache transfer latencies.
4390 and for NUMA systems with large remote-access
4403 Set the page-cache refill delay (in milliseconds)
4404 in response to low-memory conditions. The range
4408 Set delay from grace-period initialization to
4421 soliciting quiescent-state help from
4433 Set the SCHED_FIFO priority of the RCU per-CPU
4436 and for the RCU grace-period kthreads (rcu_bh,
4438 set, valid values are 1-99 and the default is 1
4439 (the least-favored priority). Otherwise, when
4440 RCU_BOOST is not set, valid values are 0-99 and
4441 the default is zero (non-realtime operation).
4447 the wakeup overhead on the global grace-period
4449 each group's NOCB grace-period kthread.
4457 batch limiting is re-enabled.
4461 RCU's force-quiescent-state scan will aggressively
4466 disable more aggressive help enlistment.
4473 Cause the grace-period kthread to get an extra
4475 it should at force-quiescent-state time.
4481 this specifies an rcu_read_unlock()-time delay
4485 of RCU-protected pointers after the relevant
4495 grace-period primitives such as call_rcu().
4506 grace-period primitives.
4509 Set test-start holdoff period. The purpose of
4518 Test the double-argument variant of kfree_rcu().
4520 rcuscale.kfree_rcu_test_single, both the single-
4521 and double-argument variants are tested.
4524 Test the single-argument variant of kfree_rcu().
4526 rcuscale.kfree_rcu_test_double, both the single-
4527 and double-argument variants are tested.
4540 Set number of RCU readers. The value -1 selects
4542 "n" less than -1 selects N-n+1, where N is again
4543 the number of CPUs. For example, -2 selects N
4544 (the number of CPUs), -3 selects N+1, and so on.
4545 A value of "n" less than or equal to -N selects
4558 complete. This is useful for hands-off automated
4565 Write-side holdoff between grace periods,
4582 Enable RCU grace-period forward-progress testing
4586 Specify the fraction of a CPU-stall-warning
4587 period to do tight-loop forward-progress testing.
4591 forward-progress tests.
4595 need_resched() during tight-loop forward-progress
4599 Use conditional/asynchronous update-side
4603 Use expedited update-side primitives, if available.
4606 Use normal (non-expedited) asynchronous
4607 update-side primitives, if available.
4610 Use normal (non-expedited) synchronous
4611 update-side primitives, if available. If all
4615 they are all non-zero.
4623 Leak an RCU-protected pointer out of the reader.
4624 This can of course result in splats, and is
4638 Set number of RCU callback-offload togglers.
4643 callback-offload toggling attempts.
4646 Set number of RCU readers. The value -1 selects
4647 N-1, where N is the number of CPUs. A value
4648 "n" less than -1 selects N-n-2, where N is again
4649 the number of CPUs. For example, -2 selects N
4650 (the number of CPUs), -3 selects N+1, and so on.
4653 Enable debug-object double-call_rcu() testing.
4656 Set time (s) after boot for CPU-hotplug testing.
4659 Set time (jiffies) between CPU-hotplug operations,
4660 or zero to disable CPU-hotplug testing.
4663 Set the number of read-then-exit kthreads used
4665 task-exit processing.
4668 The number of times in a given read-then-exit
4669 episode that a set of read-then-exit kthreads
4674 read-then-exit testing episodes.
4677 Set task-shuffle interval (s). Shuffling tasks
4678 allows some CPUs to go into dyntick-idle mode
4683 is useful for hands-off automated testing.
4687 warnings, zero to disable.
4692 to any other stall-related activity.
4698 Disable interrupts while stalling if set.
4702 grace-period kthread to test RCU CPU stall
4703 warnings, zero to disable. If both stall_cpu
4728 Test RCU's dyntick-idle handling. See also the
4754 Use expedited grace-period primitives, for
4757 but can increase CPU utilization, degrade
4758 real-time latency, and degrade energy efficiency.
4762 Use only normal grace-period primitives,
4765 real-time latency, CPU utilization, and
4766 energy efficiency, but can expose users to
4767 increased grace-period latency. This parameter
4774 only normal grace-period primitives. No effect
4780 post-boot attempt at an expedited RCU grace
4781 period to instead use normal non-expedited
4782 grace-period processing.
4788 number avoids disturbing real-time workloads,
4793 messages. Disable with a value less than or equal
4805 force - Override the decision by the kernel to hide the
4833 Set test-start holdoff period. The purpose of
4842 but the default has already reduced the per-pass
4847 Set number of readers. The default value of -1
4856 Set the read-side critical-section duration,
4860 Specify the read-protection implementation to test.
4879 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
4887 reservetop= [X86-32]
4904 See Documentation/power/swsusp-and-swap-files.rst
4917 no Disable hibernation and resume.
4920 during restoration read-only).
4939 ring3mwait=disable
4940 [KNL] Disable ring 3 MONITOR/MWAIT feature on supported
4943 ro [KNL] Mount root device read-only on boot
4946 on Mark read-only kernel memory as read-only (default).
4947 off Leave read-only kernel memory writable for debugging.
4952 debug-uart get routed to the D+ and D- pins of the usb
4974 rw [KNL] Mount root device read-write on boot
4990 schedstats= [KNL,X86] Enable or disable scheduled statistics.
4991 Allowed values are enable and disable. This feature
5014 to 10 seconds for built-in smp_call_function()
5021 that requesting even small non-zero numbers of
5022 seconds can result in RCU CPU stall warnings,
5028 The default of -1 specifies a number of kthreads
5033 test before initiating CPU-hotplug operations.
5037 CPU-hotplug operations. Specifying zero (which
5038 is the default) disables CPU-hotplug operations.
5044 Non-zero values are useful for automated tests.
5057 preempt_disable() to disable CPU hotplug
5067 "wait" parameter. A value of -1 selects the
5068 default if all other weights are -1. However,
5070 value of -1 will instead select a weight of zero.
5075 non-zero "wait" parameter. See weight_single.
5082 this weighting can place serious IPI load
5088 non-zero "wait" parameter. See weight_single
5100 non-zero "wait" parameter. See weight_single
5107 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
5108 1 -- enable.
5116 selinux= [SELINUX] Disable or enable SELinux at boot time.
5119 0 -- disable.
5120 1 -- enable.
5123 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
5126 0 -- disable.
5127 1 -- enable.
5130 serialnumber [BUGS=X86-32]
5135 simeth= [IA-64]
5145 Disable merging of slabs with similar size. May be
5149 layout control by attackers can usually be
5153 unchanged). Debug options disable merging on their
5166 slub_debug can create guard zones around objects and
5201 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
5202 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
5203 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
5204 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
5205 smsc-ircc2.ircc_irq= [HW] IRQ line
5206 smsc-ircc2.ircc_dma= [HW] DMA channel
5207 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
5217 Default: -1 (no limit)
5220 [KNL] Should the soft-lockup detector generate panics.
5223 A value of 1 instructs the soft-lockup detector
5224 to panic the machine when a soft-lockup occurs. It is
5227 respective build-time switch to that functionality.
5230 [KNL] Should the soft-lockup detector generate
5235 See Documentation/admin-guide/laptops/sonypi.rst
5242 on - unconditionally enable, implies
5244 off - unconditionally disable, implies
5246 auto - kernel detects whether your CPU model is
5258 Selecting 'off' will disable both the kernel and
5261 Specific mitigations can also be selected manually:
5263 retpoline - replace indirect branches
5264 retpoline,generic - google's original retpoline
5265 retpoline,amd - AMD-specific minimal thunk
5275 on - Unconditionally enable mitigations. Is
5278 off - Unconditionally disable mitigations. Is
5281 prctl - Indirect branch speculation is enabled,
5282 but mitigation can be enabled via prctl
5287 - Like "prctl" above, but only STIBP is
5293 - Same as "prctl" above, but all seccomp
5298 - Like "seccomp" above, but only STIBP is
5303 auto - Kernel selects the mitigation depending on
5313 [HW] Control Speculative Store Bypass (SSB) Disable mitigation
5321 is that such stores are unlikely and that they can
5326 store can be used in a cache side channel attack, for
5335 on - Unconditionally disable Speculative Store Bypass
5336 off - Unconditionally enable Speculative Store Bypass
5337 auto - Kernel detects whether the CPU model contains an
5343 prctl - Control Speculative Store Bypass per thread
5347 seccomp - Same as "prctl" above, but all seccomp threads
5348 will disable SSB unless they explicitly opt out.
5355 on,auto - On Power8 and Power9 insert a store-forwarding
5359 off - No action.
5378 off - not enabled
5380 warn - the kernel will emit rate-limited warnings
5388 fatal - the kernel will send SIGBUS to applications
5393 ratelimit:N -
5413 Certain CPUs are vulnerable to an MDS-like
5414 exploit which can leak bits from the random
5418 microcode. However, the microcode fix can cause
5423 The microcode mitigation can be disabled with
5426 off: Disable mitigation and remove
5431 grace-period sequence counter wrap for the
5432 srcu_data structure's ->srcu_gp_seq_needed field.
5443 expediting. Set to zero to disable automatic
5447 Speculative Store Bypass Disable control
5454 force-on: Unconditionally enable mitigation for
5456 force-off: Unconditionally disable mitigation for
5472 disable the stack depot thereby saving the static memory
5479 stacktrace_filter=[function-list]
5481 will trace at boot up. function-list is a comma-separated
5482 list of functions. This list can be changed at run
5489 Set the STI (builtin display/keyboard on the HP-PARISC
5491 as the initial boot-console.
5532 to global on non-NUMA machines)
5538 RPC calls that can be sent from the client to a
5557 controller if no parameter or 1 is given or disable
5558 it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)
5560 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
5562 <int> -- Number of I/O TLB slabs
5563 force -- force using of bounce buffers even if they
5565 noforce -- Never use bounce buffers (for debugging)
5579 Enable/disable old style sysfs layout for old udev
5589 Ignore sysrq setting - this boot parameter will
5597 cache size. See Documentation/networking/ip-sysctl.rst
5603 Specify "mem" (for Suspend-to-RAM) or "standby" (for
5608 wakeup-capable RTC alarm.
5614 -1: disable all active trip points in all thermal zones
5618 -1: disable all critical trip points in all thermal zones
5622 Set to disable actions on ACPI thermal zone
5626 1: disable ACPI thermal control
5629 -1: disable all passive trip points
5635 <deci-seconds>: poll all this frequency
5657 Prevent the CPU-hotplug component of torturing
5661 Dump the ftrace buffer at torture-test shutdown,
5662 even if there were no errors. This can be a
5665 with rotating-rust storage.
5670 disables verbose-printk() sleeping.
5673 Duration of each verbose-printk() sleep in jiffies.
5689 trace_event=[event-list]
5691 to facilitate early boot debugging. The event-list is a
5692 comma-separated list of trace events to enable. See
5695 trace_options=[option-list]
5696 [FTRACE] Enable or disable tracer options at boot.
5697 The option-list is a comma delimited list of options
5698 that can be enabled or disabled just as if you were
5723 The tp_printk_stop_on_boot (see below) can also be used
5730 frequency tracepoints such as irq or sched, can cause
5734 When tp_printk (above) is set, it can cause a lot of noise
5743 [FTRACE] enable this option to disable tracing when a
5744 warning is hit. This turns off "tracing_on". Tracing can
5752 This option can also be set at run time via the sysctl
5758 Can be used to control the default behavior of the system
5760 See Documentation/admin-guide/mm/transhuge.rst
5768 - "tpm"
5769 - "tee"
5775 tsc= Disable clocksource stability checks for TSC.
5780 high-resolution timer mode on older hardware, and in
5783 Used to run time disable IRQ_TIME_ACCOUNTING on any
5785 can add overhead.
5789 [x86] nowatchdog: disable clocksource watchdog. Used
5806 on - Enable TSX on the system. Although there are
5809 several previous speculation-related CVEs, and
5813 off - Disable TSX on the system. (Note that this
5821 auto - Disable TSX if X86_BUG_TAA is present,
5826 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5832 Similar to Micro-architectural Data Sampling (MDS)
5835 exploit against CPU internal buffers which can forward
5840 data can be used in a cache side channel attack, to
5847 full - Enable TAA mitigation on vulnerable CPUs
5850 full,nosmt - Enable TAA mitigation and disable SMT on
5853 vulnerable to cross-thread TAA attacks.
5854 off - Unconditionally disable TAA mitigation
5856 On MDS-affected machines, tsx_async_abort=off can be
5858 are mitigated with the same mechanism so in order to disable
5868 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5874 See also Documentation/input/devices/joystick-parport.rst
5876 udbg-immortal [PPC] When debugging early kernel crashes that
5882 Set number of hash buckets for UDP/UDP-Lite connections
5884 uhci-hcd.ignore_oc=
5886 Some badly-designed motherboards generate lots of
5897 (default -1 = authorized except for wireless USB,
5903 for newly-detected USB devices (default 2). This
5931 [USB] Specifies timeout for the initial 64-byte
5935 usbcore.nousb [USB] Disable the USB subsystem
5938 [USB] A list of quirk entries to augment the built-in
5941 VendorID:ProductID:Flags. The IDs are 4-digit hex
5943 will change the built-in quirk; setting it if it is
5948 a 255-byte read);
5949 b = USB_QUIRK_RESET_RESUME (device can't resume
5951 c = USB_QUIRK_NO_SET_INTF (device can't handle
5952 Set-Interface requests);
5953 d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't
5956 e = USB_QUIRK_RESET (device can't be reset
5960 bNumInterfaces count, and can't handle
5971 (bInterval-1).
5976 i = USB_QUIRK_DEVICE_QUALIFIER (device can't
5982 k = USB_QUIRK_NO_LPM (device can't handle Link
6006 usb-storage.delay_use=
6010 usb-storage.quirks=
6012 override the built-in unusual_devs list. List
6015 and Product ID values (4-digit hex numbers) and
6017 to a common usb-storage quirk flag as follows:
6059 medium is write-protected).
6068 1 - undefined instruction events
6069 2 - system calls
6070 4 - invalid data aborts
6071 8 - SIGSEGV faults
6072 16 - SIGBUS faults
6086 vdso=0: disable VDSO mapping
6088 vdso32= [X86] Control the 32-bit vDSO
6089 vdso32=1: enable 32-bit VDSO
6090 vdso32=0 or vdso32=2: disable 32-bit VDSO
6100 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
6102 vector= [IA-64,SMP]
6122 <size> := size (can use standard suffixes
6131 Can be used multiple times for multiple devices.
6133 vga= [BOOT,X86-32] Select a particular video mode
6135 Documentation/admin-guide/svga.rst.
6150 - Disable all of the above options
6153 size of <nn>. This can be used to increase the
6154 minimum size (128MB on x86). It can also be used to
6171 vsyscall= [X86-64]
6174 code). Most statically-linked binaries and older
6177 targets for exploits that can control RIP.
6198 see VGA-softcursor.txt. Default: 2 = underline.
6203 This is a 16-member array composed of values
6204 ranging from 0-255.
6209 This is a 16-member array composed of values
6210 ranging from 0-255.
6215 This is a 16-member array composed of values
6216 ranging from 0-255.
6221 Set system-wide default UTF-8 mode for all tty's.
6222 Default is 1, i.e. UTF-8 mode is enabled for all
6227 Format=<-1|0|1>
6228 Set system-wide default for whether a cursor
6229 is shown on new VTs. Default is -1,
6234 vt.italic= [VT] Default color for italic text; 0-15.
6237 vt.underline= [VT] Default color for underlined text; 0-15.
6241 see Documentation/watchdog/watchdog-parameters.rst
6242 or other driver-specific files in the
6254 If CONFIG_WQ_WATCHDOG is configured, workqueue can
6259 it can be updated at runtime by writing to the
6267 whatever reason, this option can be used. Note
6268 that this also can be controlled per-workqueue for
6272 Per-cpu workqueues are generally preferred because
6274 locality; unfortunately, per-cpu workqueues tend to
6277 Enabling this makes the per-cpu workqueues which
6292 forces round-robin CPU selection to flush out
6297 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
6301 xen_512gb_limit [KNL,X86-64,XEN]
6311 ide-disks -- unplug primary master IDE devices
6312 aux-ide-disks -- unplug non-primary-master IDE devices
6313 nics -- unplug network devices
6314 all -- unplug all emulated devices (NICs and IDE disks)
6315 unnecessary -- unplugging emulated devices is
6318 never -- do not unplug even if version check succeeds
6336 [KNL,X86,XEN] Disable the vector callback for Xen
6341 to Xen, for use by other domains. Can be also changed at runtime
6345 xen_timer_slop= [X86-64,XEN]
6361 Boolean parameter to disable using fifo event handling
6363 preferred over the 2-level event handling, as it is
6390 xhci-hcd.quirks [USB,KNL]
6392 host controller quirks. Meaning of each bit can be
6408 can be written using xmon commands.
6410 memory, and other data can't be written using