Lines Matching +full:no +full:- +full:tick +full:- +full:in +full:- +full:suspend
7 accepted. In most cases the overhead is negligible.
16 force -- enable ACPI if default was off
17 on -- enable ACPI but allow fallback to DT [arm64,riscv64]
18 off -- disable ACPI if default was on
19 noirq -- do not use ACPI for IRQ routing
20 strict -- Be less tolerant of platforms that are not
22 rsdt -- prefer RSDT over (default) XSDT
23 copy_dsdt -- copy DSDT to memory
37 If set to vendor, prefer vendor-specific driver
62 debug output. Bits in debug_layer correspond to a
63 _COMPONENT in an ACPI source file, e.g.,
65 Bits in debug_level correspond to a level in
69 Documentation/firmware-guide/acpi/debug.rst for more information about
85 { strict | lax | no }
88 only). IO ports and memory declared in ACPI might be
89 used by the ACPI subsystem in arbitrary AML code and
97 no: ACPI OperationRegions are not marked as reserved,
98 no further checks are performed.
107 default in APIC mode
111 default in PIC mode
122 by unsupported hardware/firmware features can result in
127 Format: <byte> or <bitmap-list>
130 Disable auto-serialization of AML methods
133 auto-serialization feature.
142 By default, SSDTs contained in the RSDT/XSDT will be
151 Ignore the ACPI-based watchdog interface (WDAT) and let
165 be necessary to carry out a cold reboot _twice_ in a
172 acpi_osi=! # disable all built-in OS vendor
174 acpi_osi=!! # enable all built-in OS vendor
178 'acpi_osi=!' can be used in combination with single or
193 'acpi_osi=' cannot be used in combination with other
195 exist in the ACPI namespace. NOTE that such command can
203 'acpi_osi=!*' can be used in combination with single or
236 For broken nForce2 BIOS resulting in XT-PIC timer.
245 as soon as the kernel's real-mode entry point is called.
261 ACPI NVS memory during suspend/hibernation and resume.
266 behave incorrectly in some ways with respect to system
267 suspend and resume to be ignored (use wisely).
273 add_efi_memmap [EFI; X86] Include EFI memory map in
283 See Documentation/sound/alsa-configuration.rst
290 align_va_addr= [X86-64]
295 CPU-intensive style benchmark, and it can vary highly in
298 32: only for 32-bit processes
299 64: only for 64-bit processes
300 on: enable for both 32- and 64-bit processes
301 off: disable for both 32- and 64-bit processes
311 Allow execve() of 32-bit applications and setting of the
313 subset of the CPUs support 32-bit EL0. When this
314 parameter is present, the set of CPUs supporting 32-bit
316 and hot-unplug operations may be restricted.
318 See Documentation/arch/arm64/asymmetric-32bit.rst for more
321 amd_iommu= [HW,X86-64]
322 Pass parameters to the AMD IOMMU driver in the system.
324 fullflush - Deprecated, equivalent to iommu.strict=1
325 off - do not initialize any AMD IOMMU found in
327 force_isolation - Force device isolation for all
332 force_enable - Force enable the IOMMU on platforms known
335 pgtbl_v1 - Use v1 page table for DMA-API (Default).
336 pgtbl_v2 - Use v2 page table for DMA-API.
337 irtcachedis - Disable Interrupt Remapping Table (IRT) caching.
339 amd_iommu_dump= [HW,X86-64]
345 amd_iommu_intr= [HW,X86-64]
348 legacy - Use legacy interrupt remapping mode.
349 vapic - Use virtual APIC mode, which allows IOMMU
351 This mode requires kvm-amd.avic=1.
360 In this mode autonomous selection is disabled.
374 selects a performance level in this range and appropriate
388 Power management functions (SPARCstation-4/5 + deriv.)
390 Disable APC CPU standby support. SPARCstation-Fox does
391 not play well with APC CPU idle - disable it if you have
398 when initialising the APIC and IO-APIC components.
399 For X86-32, this can also be used to specify an APIC
422 0 -- disable.
423 1 -- enable.
426 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
468 audit= [KNL] Enable the audit sub-system
470 0 | off - kernel audit is disabled and can not be
472 unset - kernel audit is initialized but disabled and
474 1 | on - kernel audit is initialized and partially
476 messages in RAM until it is fully enabled by the
487 0 - Disable the BAU.
488 1 - Enable the BAU.
489 unset - Disable the BAU.
516 See Documentation/block/cmdline-partition.rst
529 See Documentation/admin-guide/bootconfig.rst
534 bttv.pll= See Documentation/admin-guide/media/bttv.rst
543 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
551 [NET] Specifies amount of time (in seconds) that
562 inclusive. See arch/mips/include/asm/pgtable-bits.h
572 - foo isn't auto-mounted if you mount all cgroups in
574 - foo isn't visible as an individually mountable
576 - if foo is an optional feature then the feature is
582 Specifying "pressure" disables per-cgroup pressure
585 cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1
589 the blacklisted controllers remain available in cgroup2.
600 nosocket -- Disable socket memory accounting.
601 nokmem -- Disable kernel memory accounting.
602 nobpf -- Disable BPF memory accounting.
607 0 -- check protection applied by kernel (includes
609 1 -- check protection requested by application.
621 numbers X. Note the Linux-specific bits are not necessarily
622 stable over kernel options, but the vendor-specific
624 X can also be a string as appearing in the flags: line
625 in /proc/cpuinfo which does not have the above
627 in /proc/cpuinfo.
632 being used by the kernel or shown in /proc/cpuinfo.
640 device driver but are enabled in hardware at reset or
642 force such clocks to be always-on nor does it reserve
643 those clocks in any way. This parameter is useful for
646 information, see Documentation/driver-api/clk.rst.
648 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
665 [X86-32] pit,hpet,tsc;
671 [SPARC64] tick
672 [X86-64] hpet,tsc
678 architected timer so that code using WFE-based polling
696 no replacement if the same CPU is chosen twice.
698 clocksource-wdtest.holdoff= [KNL]
699 Set the time in seconds that the clocksource
704 cma=nn[MG]@[start[MG][-end[MG]]]
715 Sets the size of kernel per-numa memory area for
717 per-numa CMA altogether. And If this option is not
719 With per-numa CMA enabled, DMA users on node nid will
721 which is located in node nid, if the allocation fails,
732 which is located in node nid, if the allocation fails,
735 cmo_free_hint= [PPC] Format: { yes | no }
737 when they are freed. This is used in CMO environments
746 com20020= [HW,NET] ARCnet - COM20020 chipset
750 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
754 ARCnet - COM90xx chipset (memory-mapped buffers)
763 the console buffer is full. In this case the
768 terminal emulator is active. If no 3270 terminal
769 emulator is used, this parameter has no effect.
783 See Documentation/admin-guide/serial-console.rst for more
793 Start an early, polled-mode console on the 8250/16550
796 MMIO inter-register address stride is either 8-bit
797 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
799 to be equivalent to 'mmio'. 'options' are specified in
801 the h/w is not re-initialized.
820 By default we print messages on consoles in
828 syscall, or to executing "dmesg -S --raw" or to reading
831 consoleblank= [KNL] The console blank (screen saver) timeout in
852 disable the cpuidle sub-system
858 disable the cpufreq sub-system
862 policy to use. This governor must be registered in the
866 [X86] Delay for N microsec between assert and de-assert
868 on every CPU online, such as boot, and resume from suspend.
875 the parameter has no effect.
878 Run kdump after running panic-notifiers and dumping
880 succeeds in any situation.
891 [KNL, X86-64, ARM64, RISCV, LoongArch] Select a region
894 See Documentation/admin-guide/kdump/kdump.rst for further details.
898 in the running system. The syntax of range is
899 start-[end] where start and end are both
901 Documentation/admin-guide/kdump/kdump.rst for an example.
904 [KNL, X86-64, ARM64, RISCV, LoongArch] range could be
912 [KNL, X86-64, ARM64, RISCV, LoongArch] range under 4G.
918 for 32-bit devices won't run out. Kernel would try to allocate
921 --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
922 --> arm64: 128MiB
923 --> riscv: 128MiB
924 --> loongarch: 128MiB
932 [KNL] Disable crypto self-tests
940 csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
943 in case a hanging CPU is detected, and that
944 CPU is pinged again in order to try to resolve
955 See also Documentation/input/devices/joystick-parport.rst
960 [KNL] Enable printing [hashed] pointers early in the
968 [KNL] verbose locking self-tests
971 self-tests.
973 (no extra messages), setting it to -1 (all bits set)
974 will print _a_lot_ more information - normally only
988 random memory corruption problems caused by bugs in
1009 Format: { on, no-mount, off }
1011 no-mount:
1016 get a -EPERM as result when trying to register files
1019 debugfs was not enabled in the kernel at all.
1020 Default value is set in build-time with a kernel configuration.
1027 APIs. In addition, this is the default hugetlb size
1032 Documentation/admin-guide/mm/hugetlbpage.rst.
1036 [KNL] Debugging option to set a timeout in seconds for
1039 drivers) that have opted in will be ignored. A timeout
1046 delayacct [KNL] Enable per-task delay accounting
1059 [HW] Report power status in /proc/i8k
1076 off: No s390 zlib hardware support
1141 entries for DMA-API debugging code. One entry is
1142 required per DMA-API allocation. Use this if the
1143 DMA-API debugging code disables itself because the
1147 With this option the DMA-API debugging driver
1162 panels may send no or incorrect EDID data sets.
1164 in the /lib/firmware directory that are used instead.
1165 Generic built-in EDID data sets are used, if one of
1168 and no file with the same name exists. Details and
1170 available in Documentation/admin-guide/edid.rst. An EDID
1175 data set with no connector name will be used for
1182 Control how the dt_cpu_ftrs device-tree binding is
1192 what data is available or for reverse-engineering.
1197 Documentation/admin-guide/dynamic-debug-howto.rst
1201 Enable debug messages in early_ioremap support. This
1207 When used with no options, the early console is
1208 determined by stdout-path property in device tree's
1213 Start an early, polled-mode console on a Cadence
1224 Start an early, polled-mode console on the 8250/16550
1226 MMIO inter-register address stride is either 8-bit
1227 (mmio) or 32-bit (mmio32 or mmio32be).
1230 in the same format described for "console=ttyS<n>"; if
1237 Start an early, polled-mode console on a pl011 serial
1241 the driver will use only 32-bit accessors to read/write
1250 Start an early, polled-mode console on a meson serial
1256 Start an early, polled-mode console on an msm serial
1262 Start an early, polled-mode console on an msm serial
1268 Start an early, polled-mode console on a serial port
1274 Start an early, polled-mode console on a serial port
1280 Use RISC-V SBI (Supervisor Binary Interface) for early
1298 Start an early, polled-mode console on a lantiq serial
1312 Start an early, polled-mode, output-only console on the
1317 Start an early, polled-mode console on the
1323 Start an early, polled-mode console on a Qualcomm
1331 coherent non-x86 systems that use system memory for
1368 You can find the port for a given device in
1378 The xen option can only be used in Xen domains.
1405 PCI bridges while in the EFI boot stub.
1406 nochunk: disable reading files in "chunks" in the EFI
1418 on all PCI bridges while in the EFI boot stub
1434 attribute is added to range 0x100000000-0x180000000 and
1435 0x10a0000000-0x1120000000.
1439 range 0x240000000-0x43fffffff.
1451 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1460 This is designed to be used in conjunction with
1463 This parameter works in place of the kgdboc parameter
1465 very early in the boot process. For early debugging
1468 elanfreq= [X86-32]
1469 See comment before function elanfreq_setup() in
1476 See Documentation/admin-guide/kdump/kdump.rst for details.
1486 (in particular on some ATI chipsets).
1492 0 -- permissive (log only, no denials).
1493 1 -- enforcing (deny and log).
1525 See also Documentation/fault-injection/.
1529 See Documentation/admin-guide/sysctl/net.rst for
1533 See Documentation/admin-guide/blockdev/floppy.rst.
1535 forcepae [X86-32]
1544 as early as possible in order to facilitate early
1566 If no parameter is passed, ftrace will dump
1571 ftrace_filter=[function-list]
1573 tracer at boot up. function-list is a comma-separated
1575 time by the set_ftrace_filter file in the debugfs
1578 ftrace_notrace=[function-list]
1579 [FTRACE] Do not trace the functions specified in
1580 function-list. This list can be changed at run time
1581 by the set_ftrace_notrace file in the debugfs
1584 ftrace_graph_filter=[function-list]
1587 function-list is a comma-separated list of functions
1589 set_graph_function file in the debugfs tracing directory.
1591 ftrace_graph_notrace=[function-list]
1592 [FTRACE] Do not trace from the functions specified in
1593 function-list. This list is a comma-separated list of
1595 set_graph_notrace file in the debugfs tracing directory.
1601 in the tracefs tracing directory. default: 0 (no limit)
1610 suspend/resume & runtime PM (consumers first, then
1613 off -- Don't create device links from firmware info.
1614 permissive -- Create device links from firmware info
1617 on -- Create device links from firmware info and use it
1618 to enforce probe and suspend/resume ordering.
1619 rpm -- Like "on", but also use to order runtime PM.
1632 strict -- Default. Continue waiting on consumers to
1634 timeout -- Give up waiting on consumers and call
1644 See also Documentation/input/devices/joystick-parport.rst
1648 gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
1658 previously stored in vector registers.
1660 This issue is mitigated by default in updated microcode.
1666 microcode mitigation. No effect if the microcode
1667 mitigation is present. Known to cause crashes in
1672 gcov_persist= [GCOV] When non-zero (default), profiling data for
1682 gpio-mockup.gpio_mockup_ranges
1685 gpio-mockup.gpio_mockup_named_lines
1717 against bounds-checking flaws in the kernel's
1723 [KNL] Should the hard-lockup detector generate
1729 for 64-bit NUMA, off otherwise.
1732 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1739 corresponding firmware-first mode error processing
1746 no Disable hibernation and resume.
1749 during restoration read-only).
1752 size of <nn>. This works even on boxes that have no
1770 has been explicitly set, resulting in the calling
1775 hpet= [X86-32,HPET] option to control HPET usage
1792 number of pages to allocate per-node can be specified.
1793 See also Documentation/admin-guide/mm/hugetlbpage.rst.
1798 [HW] The size of the HugeTLB pages. This is used in
1804 Documentation/admin-guide/mm/hugetlbpage.rst.
1815 boot-time allocation of gigantic hugepages is skipped.
1843 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1849 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1866 (disabled by default, and as a pre-condition
1868 i8042.direct [HW] Put keyboard port into non-translated mode
1882 suspend-to-ram transitions, only during s2r
1906 -1 -- never invert brightness
1907 0 -- machine default
1908 1 -- force brightness inversion
1910 ia32_emulation= [X86-64]
1912 When true, allows loading 32-bit programs and executing 32-bit
1927 In such case C2/C3 won't be used again.
1928 idle=nomwait: Disable mwait for CPU C-states
1956 legacy only accept legacy-NaN binaries, if supported
1958 2008 only accept 2008-NaN binaries, if supported
1964 encodings, so if no FPU hardware is present or it has
1967 'relaxed' straps the emulator for both legacy-NaN and
1968 2008-NaN, whereas 'strict' enables legacy-NaN only on
1977 Ignore loglevel setting - this will print /all/
2009 in crypto/hash_info.h.
2044 Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
2045 "ima-sigv2" }
2046 Default: "ima-ng"
2078 initcall_blacklist= [KNL] Do not execute a comma-separated list of
2079 initcall functions. Useful for debugging built-in
2097 load the initrd. If an initrd is compiled in or
2098 specified in the bootparams, it takes priority over this
2115 override in debugfs after boot.
2124 0 -- basic integrity auditing messages. (Default)
2125 1 -- additional integrity auditing messages.
2135 bypassed by not enabling DMAR with this option. In
2153 could harm performance of some high-throughput
2162 1 to 9 specify maximum depth of C-state.
2171 algorithms for p-state selection. There are two
2172 P-state selection algorithms provided by
2173 intel_pstate in the active mode: powersave and
2175 on whether or not the hardware managed P-states
2176 (HWP) feature has been enabled in the processor
2182 used along with the hardware-managed P-states (HWP)
2186 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2187 instead of acpi-cpufreq may disable platform features, such
2189 P-States information being indicated to OSPM and therefore
2192 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2205 Allow per-logical-CPU P-State performance control limits using
2208 intremap= [X86-64, Intel-IOMMU]
2213 BIOS x2APIC opt-out request will be ignored
2237 0 - Try to allocate a 32-bit DMA address first, before
2239 1 - Allocate directly from the full usable range,
2241 greater than 32-bit addressing.
2245 0 - Lazy mode.
2251 1 - Strict mode.
2254 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2256 legacy driver-specific options takes precedence.
2261 0 - Use IOMMU translation for DMA.
2262 1 - Bypass the IOMMU for DMA.
2263 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2265 io7= [HW] IO7 for Marvel-based Alpha systems
2266 See comment before marvel_specify_io7 in
2277 No delay
2280 See Documentation/admin-guide/nfs/nfsroot.rst.
2300 to let secondary kernels in charge of setting up
2304 Enables support for pseudo-NMIs in the kernel. This
2323 [Deprecated - use cpusets instead]
2324 Format: [flag-list,]<cpu-list>
2327 specified in the flag list (default: domain):
2330 Disable the tick when a single task runs.
2332 A residual 1Hz tick is offloaded to workqueues, which you
2350 move in and out of an isolated set anytime.
2355 "number of CPUs in system - 1".
2374 CPUs then this parameter has no effect on the
2378 housekeeping CPUs has no influence on those
2381 The format of <cpu-list> is described above.
2385 ivrs_ioapic [HW,X86-64]
2386 Provide an override to the IOAPIC-ID<->DEVICE-ID
2387 mapping provided in the IVRS ACPI table.
2390 For example, to map IOAPIC-ID decimal 10 to
2396 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2399 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2403 ivrs_hpet [HW,X86-64]
2404 Provide an override to the HPET-ID<->DEVICE-ID
2405 mapping provided in the IVRS ACPI table.
2408 For example, to map HPET-ID decimal 10 to
2414 * To map HPET-ID decimal 0 to PCI device 00:14.0
2417 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2421 ivrs_acpihid [HW,X86-64]
2422 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2423 mapping provided in the IVRS ACPI table.
2426 For example, to map UART-HID:UID AMD0020:0 to
2432 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2435 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2450 useful for debugging when something happens in the window
2456 kernelcore= [KNL,X86,IA-64,PPC]
2459 the kernel for non-movable allocations. The requested
2460 amount is spread evenly throughout all nodes in the
2462 movable memory in its own zone, ZONE_MOVABLE. In the
2469 subsystem. Note that allocations like PTEs-from-HighMem
2473 It is possible to specify the exact amount of memory in
2475 memory in the form of "nn%", or "mirror". If "mirror"
2477 for non-movable allocations and remaining memory is used
2485 optional and is the number seconds in between
2486 each poll cycle to the debug port in case you need
2488 gdb or control-c on the dbgp connection. When
2489 not using this parameter you use sysrq-g to break into
2494 or a supported polling keyboard driver (non-usb).
2504 characters and can work in polling mode, you can use
2521 Configure the RouterBoard 532 series on-chip
2524 kmemleak= [KNL] Boot-time kmemleak enable/disable
2530 kprobe_event=[probe-list]
2532 The probe-list is a semicolon delimited list of probe
2562 execution by eliminating the write-protection faults
2573 disabled, all huge pages in a memslot will be eagerly
2607 back to huge pages. If the value is a non-zero N, KVM will
2612 kvm-amd.nested= [KVM,AMD] Control nested virtualization feature in
2615 kvm-amd.npt= [KVM,AMD] Control KVM's use of Nested Page Tables,
2616 a.k.a. Two-Dimensional Page Tables. Default is 1
2620 kvm-arm.mode=
2625 nvhe: Standard nVHE-based mode, without support for
2628 protected: nVHE-based mode with support for guests whose
2631 nested: VHE-based mode with support for nested
2640 kvm-arm.vgic_v3_group0_trap=
2641 [KVM,ARM] Trap guest accesses to GICv3 group-0
2644 kvm-arm.vgic_v3_group1_trap=
2645 [KVM,ARM] Trap guest accesses to GICv3 group-1
2648 kvm-arm.vgic_v3_common_trap=
2652 kvm-arm.vgic_v4_enable=
2664 kvm-intel.ept= [KVM,Intel] Control KVM's use of Extended Page Tables,
2665 a.k.a. Two-Dimensional Page Tables. Default is 1
2669 kvm-intel.emulate_invalid_guest_state=
2671 state. Ignored if kvm-intel.enable_unrestricted_guest=1,
2677 kvm-intel.flexpriority=
2682 kvm-intel.nested=
2683 [KVM,Intel] Control nested virtualization feature in
2686 kvm-intel.unrestricted_guest=
2692 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2693 CVE-2018-3620.
2702 Default is cond (do L1 cache flush in specific instances)
2704 kvm-intel.vpid= [KVM,Intel] Control KVM's use of Virtual Processor
2716 In vulnerable processors, the speculatively
2717 forwarded data can be used in a cache side channel
2724 on - enable the interface for the mitigation
2735 enables all mitigations in the
2741 when the first VM is started in a
2759 when the first VM is started in a
2771 when the first VM is started in a
2777 warn when a VM is started in a potentially
2789 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2795 lapic [X86-32,APIC] Enable the local APIC even if BIOS
2799 value for LAPIC timer one-shot implementation. Default
2800 back to the programmable timer unit in the LAPIC.
2804 in C2 power state.
2818 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
2822 libata.force= [LIBATA] Force configurations. The format is a comma-
2834 first fan-out link behind PMP device. It does not
2839 as there is no ambiguity, shortcut notation is allowed.
2848 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2855 * rstonce: only attempt one reset during hot-unplug
2858 * [no]dbdelay: Enable or disable the extra 200ms delay
2862 * [no]ncq: Turn on or off NCQ.
2864 * [no]ncqtrim: Enable or disable queued DSM TRIM.
2866 * [no]ncqati: Enable or disable NCQ trim on ATI chipset.
2868 * [no]trim: Enable or disable (unqueued) TRIM.
2874 * [no]dma: Turn on or off DMA transfers.
2881 * [no]dmalog: Enable or disable the use of the
2884 * [no]iddevlog: Enable or disable access to the
2887 * [no]logdir: Enable or disable access to the general
2898 * [no]lpm: Enable or disable link power management.
2900 * [no]setxfer: Indicate if transfer speed mode setting
2903 * [no]fua: Disable or enable FUA (Force Unit Access)
2937 Set the time limit in jiffies for a lock
2939 will result in a splat once they do complete.
2950 Specify the number of self-propagating call_rcu()
2953 in progress at any given time. Defaults to 0,
2957 Specify the duration in milliseconds for the
2958 occasional long-duration lock hold time. Defaults
2969 Set the number of locking read-acquisition kthreads.
2974 Set the number of locking write-acquisition kthreads.
2977 Set time (s) after boot for CPU-hotplug testing.
2980 Set time (s) between CPU-hotplug operations, or
2981 zero to disable CPU-hotplug testing.
2984 Do periodic testing of real-time lock priority
2989 non-real-time spinlocks, due to their disabling
2990 of preemption. Note that non-realtime mutexes
3003 Set task-shuffle interval (jiffies). Shuffling
3004 tasks allows some CPUs to go into dyntick-idle
3009 is useful for hands-off automated testing.
3028 Run the write-side locktorture kthreads at
3029 sched_set_fifo() real-time priority.
3046 7 (KERN_DEBUG) debug-level messages
3049 in bytes. n must be a power of two and greater
3056 logo.nologo [FB] Disables display of the built-in Linux logo.
3065 specified in addition to the ports) causes
3074 an IEEE 1284-compliant printer is attached; if
3080 time-consuming boot-time autodetection (up to 250 ms per
3087 will cause delays in the kernel to be wrong, leading to
3089 unlikely, in the extreme case this might damage your
3101 machvec= [IA-64] Force the use of a particular machine-vector
3102 (machvec) in a generic kernel.
3107 Example: machtype=lemote-yeeloong-2f-7inch
3109 max_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory greater
3122 (loop.max_loop) unconditionally pre-created at init time. The default
3125 devices can be requested on-demand with the
3126 /dev/loop-control interface.
3128 mce [X86-32] Machine Check Exception
3130 mce=option [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
3133 See Documentation/admin-guide/md.rst.
3140 Control mitigation for the Micro-architectural Data
3147 In vulnerable processors, the speculatively
3148 forwarded data can be used in a cache side channel
3155 full - Enable MDS mitigation on vulnerable CPUs
3156 full,nosmt - Enable MDS mitigation and disable
3158 off - Unconditionally disable MDS mitigation
3160 On TAA-affected machines, mds=off can be prevented by
3162 mitigated with the same mechanism so in order to disable
3169 For details see: Documentation/admin-guide/hw-vuln/mds.rst
3175 Amount of memory to be used in cases as follows:
3183 [ARC,MICROBLAZE] - the limit applies only to low memory,
3186 [ARM64] - only limits memory covered by the linear
3195 in above case 3, memory may need be hot added after boot
3199 [ARM,MIPS] - override the memory layout reported by
3206 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
3213 per-device physically contiguous DMA buffers.
3221 See Documentation/admin-guide/mm/memory-hotplug.rst.
3246 Example: Exclude memory from 0x18690000-0x1869ffff
3260 memmap=<size>%<offset>-<oldtype>+<newtype>
3262 from <oldtype> to <newtype>. If "-<oldtype>" is left
3271 memory when doing things like suspend/resume.
3277 repeatable BIOS-originated corruption always
3282 By default it checks for corruption in the low
3285 corruption in more or less memory.
3304 allocations in some configurations (e.g. small
3306 The state of the flag can be read in
3321 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
3329 Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
3332 mem_sleep_default= [SUSPEND] Default system suspend mode:
3333 s2idle - Suspend-To-Idle
3334 shallow - Power-On Suspend or equivalent (if supported)
3335 deep - Suspend-To-RAM or equivalent (if supported)
3336 See Documentation/admin-guide/pm/sleep-states.rst.
3338 mfgpt_irq= [IA-32] Specify the IRQ to use for the
3339 Multi-Function General Purpose Timers on AMD Geode
3342 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
3354 min_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory below this
3361 0 - The attached screen is the 3.5" TFT
3362 1 - The attached screen is the 7" TFT
3363 2 - The VGA Shield is attached (1024x768)
3367 b - Enable backlight. The TFT backlight pin will be
3371 c - Enable the s3c camera interface.
3372 t - Reserved for enabling touchscreen support. The
3373 touchscreen support is not enabled in the mainstream
3375 in the "bleeding edge" mini2440 support kernel at
3376 https://repo.or.cz/w/linux-2.6/mini2440.git
3381 arch-independent options, each of which is an
3382 aggregation of existing arch-specific options.
3405 ssbd=force-off [ARM64]
3418 have other ways of avoiding SMT-based attacks.
3445 operation. Exposed data could originate or end in
3453 full - Enable mitigation on vulnerable CPUs
3455 full,nosmt - Enable mitigation and disable SMT on
3458 off - Unconditionally disable mitigation
3463 mitigated with the same mechanism so in order to
3471 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3474 If no <bool> value is specified or if the value
3501 module_blacklist= [KNL] Do not load a comma-separated list of
3508 touchpads working in absolute mode only).
3515 movablecore= [KNL,X86,IA-64,PPC]
3526 movable_node [KNL] Boot-time switch to make hotplugable memory
3533 Format: <name>,<region-number>,<size>,<offset>
3536 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3544 See arch/arm/mach-s3c/mach-jive.c
3580 something different and driver-specific.
3581 This usage is only documented in each driver source
3585 [NET] Specifies amount of time (in seconds) that
3620 [NFS] enable 64-bit inode numbers.
3621 If zero, the NFS client will fake up a 32-bit inode
3623 of returning the full 64-bit number.
3624 The default is to return 64-bit inode numbers.
3634 callbacks the client will process in parallel for
3642 Note that there is little point in setting this
3650 'sec=sys' security flavour. In effect it is
3659 [NFS4] Specify an additional fixed unique ident-
3668 no guarantees that the file will remain unchanged
3678 information in exchange_id requests.
3679 If zero, no implementation identification information
3690 driver. A non-zero value sets the minimum interval
3691 in seconds between layoutstats transmissions.
3695 server-to-server copies for which this server is
3707 server-to-server copy, knfsd temporarily mounts
3708 the source server. It caches the mount in case
3714 See Documentation/admin-guide/nfs/nfsroot.rst.
3716 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3717 See Documentation/admin-guide/nfs/nfsroot.rst.
3720 See Documentation/admin-guide/nfs/nfsroot.rst.
3723 Dump stacks even of idle CPUs in response to an
3724 NMI stack-backtrace request.
3733 0 - turn hardlockup detector in nmi_watchdog off
3734 1 - turn hardlockup detector in nmi_watchdog on
3746 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3750 no4lvl [RISCV] Disable 4-level and 5-level paging modes. Forces
3751 kernel to use 3-level paging instead.
3753 no5lvl [X86-64,RISCV] Disable 5-level paging mode. Forces
3754 kernel to use 4-level paging instead.
3757 caches in the slab allocator. Saves per-node memory,
3766 IOAPICs that may be present in the system.
3773 [HW] Never suspend the console
3774 Disable suspending of consoles during suspend and
3778 debugging driver suspend/resume hooks). This may
3794 no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel.
3796 noexec [IA-64]
3798 noexec32 [X86-64]
3799 This affects only 32-bit executables.
3800 noexec32=on: enable non-executable mappings (default)
3802 noexec32=off: disable non-executable mappings
3813 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3815 legacy floating-point registers on task switch.
3817 nohalt [IA-64] Tells the kernel not to use the power saving
3819 power-consumption. On the positive side, it reduces
3820 interrupt wake-up latency, which may improve performance
3821 in certain environments such as networked servers or
3822 real-time systems.
3831 difficult since unequal pointers can no longer be
3832 compared. However, if this command-line option is
3841 busy wait in do_idle() and not use the arch_cpu_idle()
3859 In kernels built with CONFIG_NO_HZ_FULL=y, set
3860 the specified list of CPUs whose tick will be stopped
3863 in this list will have their RCU callbacks offloaded,
3864 just as if they had also been called out in the
3873 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
3875 [Deprecated - use intremap=off]
3877 nointroute [IA-64]
3883 noirqdebug [X86-32] Disables the code which attempts to detect and
3888 nojitter [IA-64] Disables jitter checking for ITC timers.
3895 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
3898 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
3900 nolapic [X86-32,APIC] Do not enable or use the local APIC.
3902 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
3904 nomca [IA-64] Disable machine check abort handling
3906 nomce [X86-32] Disable Machine Check Exception
3908 nomfgpt [X86-32] Disable Multi-Function General Purpose
3914 not load if they could possibly displace the pre-
3917 perform display-mode changes or accelerated rendering.
3930 nopcid [X86-64] Disable the PCID cpu feature.
3933 in some Intel CPUs.
3935 nopti [X86-64]
3940 as generic guest with no PV drivers. Currently support
3951 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
3957 nosbagart [IA-64]
3959 no-scroll [VGA] Disables scrollback.
3960 This is required for the Braillex ib80-piezo Braille
3963 nosgx [X86-64,SGX] Disables Intel SGX kernel support.
3983 nosoftlockup [KNL] Disable the soft-lockup detector.
3988 nospectre_bhb [ARM64] Disable all mitigations for Spectre-BHB (branch
3994 possible in the system.
4001 no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV] Disable
4011 [PPC] Don't flush the L1-D cache after accessing user data.
4017 without any limit and this data is stored in memory,
4020 data will be no longer available. This parameter
4024 no-vmw-sched-clock
4029 soft-lockup and NMI watchdog (hard-lockup).
4033 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
4036 LEGACY_XAPIC_DISABLED bit set in the
4041 enabling legacy floating-point and sse state.
4043 noxsaveopt [X86] Disables xsaveopt used in saving x86 extended
4050 noxsaves [X86] Disables xsaves and xrstors used in saving and
4051 restoring x86 extended register state in compacted
4054 in standard form of xsave area. By using this
4059 This parameter sets the maximum duration, in
4067 nptcg= [IA-64] Override max number of concurrent global TLB
4074 number of already plugged CPU during bootup, later in
4076 n. So during boot up some boot time memory for per-cpu
4077 variables need be pre-allocated for later physical cpu
4092 See Documentation/admin-guide/sysctl/vm.rst for details.
4095 See Documentation/core-api/debugging-via-ohci1394.rst for more
4110 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
4114 boundary - index of last SLC block on Flex-OneNAND.
4116 lock - Configure if Flex-OneNAND boundary should be locked.
4130 running on a platform with a direct-mapped memory-side
4136 page_owner= [KNL] Boot-time page_owner enabling option.
4138 each page is disabled in default. With this switch,
4142 page_poison= [KNL] Boot-time parameter changing the state of
4160 panic_on_taint= Bitmask for conditionally calling panic() in add_taint()
4164 called with any of the flags in this set.
4169 See Documentation/admin-guide/tainted-kernels.rst for
4183 bit 5: print all printk messages in buffer
4184 bit 6: print all CPUs backtrace (if available in the arch)
4186 so there are risks of losing older messages in the log.
4207 Parallel ports are assigned in the order they
4212 Configure VIA parallel port to operate in
4214 computer where firmware has no options for setting
4221 Set to non-zero to probe primary and secondary ISA
4222 port ranges on PCI systems where no PCI PATA device
4227 Set to non-zero if a chip is present that snoops speed
4275 Set to non-zero to probe tertiary and further ISA
4285 corresponding bits in the mask to 1. Bit 0 is for
4286 the first port in the list above (0x1f0), and so on.
4291 Set to non-zero to probe QDI controllers. By default
4296 Set to non-zero to probe Winbond controllers. Use
4320 specified in one of the following formats:
4338 devices in the system.
4343 bios [X86-32] force use of PCI BIOS, don't access
4345 has a non-standard PCI host bridge.
4346 nobios [X86-32] disallow use of PCI BIOS, only direct
4351 Mechanism 1 (config address in IO port 0xCF8,
4352 data in IO port 0xCFC, both 32-bit).
4354 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
4355 the function, IO port 0xCFA, also 8-bit, sets
4357 through ports 0xC000-0xCFFF).
4364 root domains (aka PCI segments, in ACPI-speak).
4372 disable the use of MSI interrupts system-wide.
4377 primary IO-APIC for bridges that cannot disable
4384 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
4408 F0000h-100000h range.
4413 assign-busses [X86] Always assign all PCI bus
4417 in the BIOS $PIR table. This is needed on
4420 notebooks. This will have no effect if ACPI
4432 for BIOS defects in host bridge _CRS methods.
4434 <linux-pci@vger.kernel.org>.
4438 a bug to <linux-pci@vger.kernel.org>.
4440 This is normally done in pci_enable_device(),
4450 bfsort Sort PCI devices into breadth-first order.
4453 nobfsort Don't sort PCI devices into breadth-first order.
4455 tuning and use the BIOS-configured MPS defaults.
4461 value (no larger than the MPS that the device
4465 configuration allows peer-to-peer DMA between
4468 that hot-added devices will work.
4483 A PCI-PCI bridge can be specified if resource
4489 for 4096-byte alignment.
4491 end-to-end CRC checking). Only effective if
4522 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4534 Specify one or more PCI devices (in the format
4541 may put more devices in an IOMMU group.
4558 dpc-native Use native PCIe service for DPC only. May
4575 Keep all power-domains already enabled by bootloader on,
4576 even if no driver has claimed them. This is useful
4588 See comments in mm/percpu.c for details on each
4592 pirq= [SMP,APIC] Manual mp-table setup
4593 See Documentation/arch/x86/i386/IO-APIC.rst.
4597 See also Documentation/admin-guide/parport.rst.
4604 This option takes over the PMU facility, so it is no
4611 pm_debug_messages [SUSPEND,KNL]
4612 Enable suspend/resume debug messages during boot up.
4616 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4625 { on | off | curr | res | no-curr | no-res }
4634 Ranges are in pairs (I/O port base and size).
4639 Ranges are in pairs (memory base and size).
4665 none - Limited to cond_resched() calls
4666 voluntary - Limited to cond_resched() and might_sleep() calls
4667 full - Any section that isn't explicitly preempt disabled
4670 print-fatal-signals=
4676 coredump - etc.
4679 you might want to try "ulimit -i unlimited".
4691 or lockdep-detected issues (only if lock debug is on).
4694 in order to provide more debug information.
4700 on - unlimited logging to /dev/kmsg from userspace
4701 off - logging to /dev/kmsg disabled
4702 ratelimit - ratelimit the logging
4709 Limit processor to maximum C-state
4713 Ignore the _CST method to determine C-states,
4720 Param: "schedule" - profile schedule points.
4721 Param: "sleep" - profile D-state sleeping (millisecs).
4723 Param: "kvm" - profile VM exits.
4724 Param: <number> - step/bucket size as a power of 2 for
4740 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
4746 [HW,MOUSE] Set desired mouse resolution, in dpi.
4753 pti= [X86-64] Control Page Table Isolation of user and
4758 on - unconditionally enable
4759 off - unconditionally disable
4760 auto - kernel detects whether your CPU model is
4766 [KNL] Number of legacy pty's. Overwrites compiled-in
4778 See Documentation/admin-guide/md.rst.
4780 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
4781 See Documentation/admin-guide/blockdev/ramdisk.rst.
4800 cross-syscall address exposures. This is only
4806 ras=option[,option,...] [KNL] RAS-specific options
4812 rcu_nocbs[=cpu-list]
4816 In kernels built with CONFIG_RCU_NOCB_CPU=y,
4817 enable the no-callback CPU mode, which prevents
4818 such CPUs' callbacks from being invoked in
4822 "p" for RCU-preempt, "s" for RCU-sched, and "g"
4826 and real-time workloads. It can also improve
4830 list of CPUs is set to no-callback mode from boot.
4833 arguments are omitted, no CPU will be set to
4834 no-callback mode from boot but the mode may be
4845 This improves the real-time response for the
4853 process in one batch.
4859 If triggered before the RCU grace-period machinery
4869 RCU grace-period cleanup.
4873 RCU grace-period initialization.
4877 RCU grace-period pre-initialization, that is,
4878 the propagation of recent CPU-hotplug changes up
4882 Set delay from grace-period initialization to
4893 Set required age in jiffies for a
4895 soliciting quiescent-state help from
4901 This calculated value may be viewed in
4907 Set the SCHED_FIFO priority of the RCU per-CPU
4910 and for the RCU grace-period kthreads (rcu_bh,
4912 set, valid values are 1-99 and the default is 1
4913 (the least-favored priority). Otherwise, when
4914 RCU_BOOST is not set, valid values are 0-99 and
4915 the default is zero (non-realtime operation).
4920 On callback-offloaded (rcu_nocbs) CPUs,
4923 use of the ->nocb_bypass list. However, in the
4924 common non-flooded case, RCU queues directly to
4925 the main ->cblist in order to avoid the extra
4926 overhead of the ->nocb_bypass list and its lock.
4928 a single jiffy, RCU pre-queues the callbacks into
4929 the ->nocb_bypass queue. The definition of "too
4938 batch limiting is re-enabled.
4942 RCU's force-quiescent-state scan will aggressively
4950 Set the page-cache refill delay (in milliseconds)
4951 in response to low-memory conditions. The range
4952 of permitted values is in the range 0:100000.
4955 Set the shift-right count to use to compute
4956 the callback-invocation batch limit bl from
4960 callbacks, the softirq handler will exit in
4963 Please note that this callback-invocation batch
4964 limit applies only to non-offloaded callback
4966 invoked in the context of an rcuoc kthread, which
4973 cache-to-cache transfer latencies.
4979 and for NUMA systems with large remote-access
4988 whole algorithm to behave better in low memory
4992 Set the number of NOCB callback kthreads in
4995 the wakeup overhead on the global grace-period
4997 each group's NOCB grace-period kthread.
5000 Cause the grace-period kthread to get an extra
5002 it should at force-quiescent-state time.
5010 every 32 callbacks in order to limit the pain
5014 In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels,
5015 this specifies an rcu_read_unlock()-time delay
5016 in microseconds. This defaults to zero.
5019 of RCU-protected pointers after the relevant
5029 per-CPU rcuc kthreads. Defaults to a non-zero
5039 grace-period primitives such as call_rcu().
5050 grace-period primitives.
5053 Set test-start holdoff period. The purpose of
5055 test until boot completes in order to avoid
5059 In kernels built with CONFIG_RCU_LAZY=y, test
5071 Test the double-argument variant of kfree_rcu().
5073 rcuscale.kfree_rcu_test_single, both the single-
5074 and double-argument variants are tested.
5077 Test the single-argument variant of kfree_rcu().
5079 rcuscale.kfree_rcu_test_double, both the single-
5080 and double-argument variants are tested.
5086 Number of allocations and frees done in an iteration.
5093 Set the minimum test run time in seconds. This
5094 does not affect the data-collection interval,
5099 Set number of RCU readers. The value -1 selects
5101 "n" less than -1 selects N-n+1, where N is again
5102 the number of CPUs. For example, -2 selects N
5103 (the number of CPUs), -3 selects N+1, and so on.
5104 A value of "n" less than or equal to -N selects
5117 complete. This is useful for hands-off automated
5124 Write-side holdoff between grace periods,
5125 in microseconds. The default of zero says
5126 no holdoff.
5129 Additional write-side holdoff between grace
5130 periods, but in jiffies. The default of zero
5131 says no holdoff.
5135 in microseconds.
5139 in microseconds.
5143 in seconds.
5147 for RCU grace-period forward-progress testing
5154 Specify the fraction of a CPU-stall-warning
5155 period to do tight-loop forward-progress testing.
5159 forward-progress tests.
5163 need_resched() during tight-loop forward-progress
5167 Use conditional/asynchronous update-side
5171 Use expedited update-side primitives, if available.
5174 Use normal (non-expedited) asynchronous
5175 update-side primitives, if available.
5178 Use normal (non-expedited) synchronous
5179 update-side primitives, if available. If all
5183 they are all non-zero.
5191 Leak an RCU-protected pointer out of the reader.
5192 This can of course result in splats, and is
5202 stress RCU, they don't participate in the actual
5206 Set number of RCU callback-offload togglers.
5210 Set the delay in milliseconds between successive
5211 callback-offload toggling attempts.
5214 Set number of RCU readers. The value -1 selects
5215 N-1, where N is the number of CPUs. A value
5216 "n" less than -1 selects N-n-2, where N is again
5217 the number of CPUs. For example, -2 selects N
5218 (the number of CPUs), -3 selects N+1, and so on.
5221 Enable debug-object double-call_rcu() testing.
5224 Set time (s) after boot for CPU-hotplug testing.
5227 Set time (jiffies) between CPU-hotplug operations,
5228 or zero to disable CPU-hotplug testing.
5231 Set the number of read-then-exit kthreads used
5233 task-exit processing.
5236 The number of times in a given read-then-exit
5237 episode that a set of read-then-exit kthreads
5241 The delay, in seconds, between successive
5242 read-then-exit testing episodes.
5245 Set task-shuffle interval (s). Shuffling tasks
5246 allows some CPUs to go into dyntick-idle mode
5251 is useful for hands-off automated testing.
5259 in warnings from preemptible RCU in addition to
5260 any other stall-related activity. Note that
5261 in kernels built with CONFIG_PREEMPTION=n and
5266 in scheduling-while-atomic splats.
5268 Use of this module parameter results in splats.
5279 grace-period kthread to test RCU CPU stall
5294 Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
5305 Test RCU's dyntick-idle handling. See also the
5320 warnings in the RCU_CPU_STALL_NOTIFIER Kconfig
5335 The value is in seconds and the maximum allowed
5340 messages. The value is in milliseconds
5343 adjusted to an arch timer tick resolution.
5360 Use expedited grace-period primitives, for
5364 real-time latency, and degrade energy efficiency.
5365 No effect on CONFIG_TINY_RCU kernels.
5368 Use only normal grace-period primitives,
5371 real-time latency, CPU utilization, and
5373 increased grace-period latency. This parameter
5374 overrides rcupdate.rcu_expedited. No effect on
5380 only normal grace-period primitives. No effect
5386 post-boot attempt at an expedited RCU grace
5387 period to instead use normal non-expedited
5388 grace-period processing.
5396 set to the default value of -1.
5399 Set the minimum number of callback-queuing-time
5400 lock-contention events per jiffy required to
5401 cause the RCU Tasks flavors to switch to per-CPU
5404 the default value of -1.
5409 of -1 allows this to be automatically (and
5411 for use in testing.
5414 Set time in jiffies during which RCU tasks will
5417 number avoids disturbing real-time workloads,
5422 cancel laziness on that CPU. Use -1 to disable
5428 Set initial timeout in jiffies for RCU task stall
5432 only printed prior to the stall-warning message
5435 seconds. A change in value does not take effect
5450 Set timeout in jiffies for RCU task stall
5453 A change in value does not take effect until
5457 Set timeout in milliseconds RCU Tasks asynchronous
5464 Set timeout in milliseconds RCU Tasks
5472 Set timeout in milliseconds RCU Tasks
5488 force - Override the decision by the kernel to hide the
5491 support, specifically around the suspend/resume
5516 Set test-start holdoff period. The purpose of
5518 test until boot completes in order to avoid
5531 but the default has already reduced the per-pass
5536 Set number of readers. The default value of -1
5545 Set the read-side critical-section duration,
5546 measured in microseconds.
5549 Specify the read-protection implementation to test.
5569 that are unused, due no driver claiming them. This may
5575 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
5583 reservetop= [X86-32]
5592 Specify the partition device for software suspend
5599 in <PAGE_SIZE> units (needed only for swap files).
5600 See Documentation/power/swsusp-and-swap-files.rst
5602 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
5616 AMD-based UNRET and IBPB mitigations alone do not stop
5618 sibling threads. For that reason, STIBP is used on pro-
5622 off - no mitigation
5623 auto - automatically select a migitation
5624 auto,nosmt - automatically select a mitigation,
5628 ibpb - On AMD, mitigate short speculation
5633 ibpb,nosmt - Like "ibpb" above but will disable SMT
5637 unret - Force enable untrained return thunks,
5638 only effective on AMD f15h-f17h based
5640 unret,nosmt - Like unret, but will disable SMT when STIBP
5675 ro [KNL] Mount root device read-only on boot
5678 on Mark read-only kernel memory as read-only (default).
5679 off Leave read-only kernel memory writable for debugging.
5680 full Mark read-only kernel memory and aliases as read-only
5686 debug-uart get routed to the D+ and D- pins of the usb
5691 see the early_lookup_bdev comment in
5692 block/early-lookup.c for details.
5697 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
5708 rootwait= [KNL] Maximum time (in seconds) to wait for root device
5717 rw [KNL] Mount root device read-write on boot
5719 S [KNL] Run init in single mode
5725 in an IOTLB flush. Default is lazy flushing before
5737 and so on. As a special case a factor of 0 imposes no
5748 incurs a small amount of overhead in the scheduler
5770 to 10 seconds for built-in smp_call_function()
5775 up to the chosen limit in seconds. Zero (the
5777 that requesting even small non-zero numbers of
5778 seconds can result in RCU CPU stall warnings,
5784 The default of -1 specifies a number of kthreads
5789 test before initiating CPU-hotplug operations.
5793 CPU-hotplug operations. Specifying zero (which
5794 is the default) disables CPU-hotplug operations.
5800 Non-zero values are useful for automated tests.
5823 "wait" parameter. A value of -1 selects the
5824 default if all other weights are -1. However,
5826 value of -1 will instead select a weight of zero.
5831 non-zero "wait" parameter. See weight_single.
5844 non-zero "wait" parameter. See weight_single
5856 non-zero "wait" parameter. See weight_single
5859 skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
5863 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
5864 1 -- enable.
5875 0 -- disable.
5876 1 -- enable.
5879 serialnumber [BUGS=X86-32]
5881 sev=option[,option...] [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
5889 to set it to "all" by meaning -- no limit here.
5895 simeth= [IA-64]
5907 allocs to different slabs, especially in hardened
5927 may poison objects when not in use. Also tracks the
5962 Specify the period of time in milliseconds
5970 using the csdlock_debug- kernel parameter.
5975 system. By default, let CSD-lock acquisition
5977 for this value provides a 5-minute timeout.
5979 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
5980 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
5981 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
5982 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
5983 smsc-ircc2.ircc_irq= [HW] IRQ line
5984 smsc-ircc2.ircc_dma= [HW] DMA channel
5985 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
5995 Default: -1 (no limit)
5998 [KNL] Should the soft-lockup detector generate panics.
6001 A value of 1 instructs the soft-lockup detector
6002 to panic the machine when a soft-lockup occurs. It is
6005 respective build-time switch to that functionality.
6008 [KNL] Should the soft-lockup detector generate
6013 See Documentation/admin-guide/laptops/sonypi.rst
6020 on - unconditionally enable, implies
6022 off - unconditionally disable, implies
6024 auto - kernel detects whether your CPU model is
6041 retpoline - replace indirect branches
6042 retpoline,generic - Retpolines
6043 retpoline,lfence - LFENCE; indirect branch
6044 retpoline,amd - alias for retpoline,lfence
6045 eibrs - Enhanced/Auto IBRS
6046 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
6047 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
6048 ibrs - use IBRS to protect kernel
6058 on - Unconditionally enable mitigations. Is
6061 off - Unconditionally disable mitigations. Is
6064 prctl - Indirect branch speculation is enabled,
6070 - Like "prctl" above, but only STIBP is
6076 - Same as "prctl" above, but all seccomp
6081 - Like "seccomp" above, but only STIBP is
6086 auto - Kernel selects the mitigation depending on
6097 off - Disable mitigation
6098 microcode - Enable microcode mitigation only
6099 safe-ret - Enable sw-only safe RET mitigation (default)
6100 ibpb - Enable mitigation by issuing IBPB on
6102 ibpb-vmexit - Issue IBPB only on VMEXIT
6103 (cloud-specific mitigation)
6111 as "Speculative Store Bypass" in which recent stores
6118 In vulnerable processors, the speculatively forwarded
6119 store can be used in a cache side channel attack, for
6128 on - Unconditionally disable Speculative Store Bypass
6129 off - Unconditionally enable Speculative Store Bypass
6130 auto - Kernel detects whether the CPU model contains an
6136 prctl - Control Speculative Store Bypass per thread
6140 seccomp - Same as "prctl" above, but all seccomp threads
6148 on,auto - On Power8 and Power9 insert a store-forwarding
6152 off - No action.
6167 boundaries will result in an alignment check exception
6171 off - not enabled
6173 warn - the kernel will emit rate-limited warnings
6179 enabled in hardware.
6181 fatal - the kernel will send SIGBUS to applications
6184 both features are enabled in hardware.
6186 ratelimit:N -
6194 If an #AC exception is hit in the kernel or in
6195 firmware (i.e. not while executing in user mode)
6196 the kernel will oops in either "warn" or "fatal"
6206 Certain CPUs are vulnerable to an MDS-like
6214 result in reduced throughput from /dev/urandom.
6226 This kernel-boot parameter defaults to 128,
6227 but takes effect only when the low-order four
6244 instead of the compile-time CONFIG_NR_CPUS.
6248 grace-period sequence counter wrap for the
6249 srcu_data structure's ->srcu_gp_seq_needed field.
6250 The greater the number of bits set in this kernel
6264 Specifies the number of no-delay instances
6271 Specifies the per-grace-period phase, number of
6272 non-sleeping polls of readers. Beyond this limit,
6278 Specifies number of microseconds of non-sleeping
6279 delay between each non-sleeping poll of readers.
6282 Specifies the number of update-side contention
6287 set for contention-based conversions to occur.
6297 force-on: Unconditionally enable mitigation for
6299 force-off: Unconditionally disable mitigation for
6301 kernel: Always enable mitigation in the
6304 interest in being mitigated too.
6308 is in page units and it defines how many pages prior
6310 growing up) the main stack are reserved for no other
6322 stacktrace_filter=[function-list]
6324 will trace at boot up. function-list is a comma-separated
6326 time by the stack_trace_filter file in the debugfs
6332 Set the STI (builtin display/keyboard on the HP-PARISC
6334 as the initial boot-console.
6335 See also comment in drivers/video/console/sticore.c.
6338 See comment in drivers/video/console/sticore.c.
6353 Limits the number of kernel HPT entries in the hash
6366 originate from a privileged port (i.e. a port in the
6377 process in parallel from a single connection.
6378 The default value is 0 (no limit).
6394 to global on non-NUMA machines)
6405 suspend.pm_test_delay=
6406 [SUSPEND]
6407 Sets the number of seconds to remain in a suspend test
6417 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
6419 <int> -- Number of I/O TLB slabs
6420 <int> -- Second integer after comma. Number of swiotlb
6423 force -- force using of bounce buffers even if they
6425 noforce -- Never use bounce buffers (for debugging)
6434 are reported in the kernel log. Sysctls registered
6440 Ignore sysrq setting - this boot parameter will
6448 cache size. See Documentation/networking/ip-sysctl.rst
6453 test_suspend= [SUSPEND]
6455 Specify "mem" (for Suspend-to-RAM) or "standby" (for
6456 standby suspend) or "freeze" (for suspend type freeze)
6460 wakeup-capable RTC alarm.
6466 -1: disable all active trip points in all thermal zones
6470 -1: disable all critical trip points in all thermal zones
6477 -1: disable all passive trip points
6483 <deci-seconds>: poll all this frequency
6484 0: no polling (default)
6505 Prevent the CPU-hotplug component of torturing
6509 Dump the ftrace buffer at torture-test shutdown,
6510 even if there were no errors. This can be a
6513 with rotating-rust storage.
6518 disables verbose-printk() sleeping.
6521 Duration of each verbose-printk() sleep in jiffies.
6527 Specify that at suspend time, the tpm driver
6539 https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
6551 tracepoint_printk kernel cmdline option has no effect.
6577 local - Use the per CPU time stamp counter
6580 in sync between CPUs.
6581 global - Event time stamps are synchronize across
6584 counter - Simple counting of events (1, 2, ..)
6588 uptime - Use jiffies as the time stamp.
6589 perf - Use the same clock that perf uses.
6590 mono - Use ktime_get_mono_fast_ns() for time stamps.
6591 mono_raw - Use ktime_get_raw_fast_ns() for time
6593 boot - Use ktime_get_boot_fast_ns() for time stamps.
6597 trace_event=[event-list]
6598 [FTRACE] Set and start specified trace events in order
6599 to facilitate early boot debugging. The event-list is a
6600 comma-separated list of trace events to enable. See
6603 trace_instance=[instance-info]
6604 [FTRACE] Create a ring buffer instance early in boot up.
6605 This will be listed in:
6623 trace_options=[option-list]
6625 The option-list is a comma delimited list of options
6639 trace_trigger=[trigger-list]
6655 See also "Event triggers" in Documentation/trace/events.rst
6662 file located in /sys/kernel/tracing/
6676 See Documentation/admin-guide/mm/transhuge.rst
6684 - "tpm"
6685 - "tee"
6686 - "caam"
6696 - "kernel"
6697 - the same value as trusted.source: "tpm" or "tee"
6698 - "default"
6699 If not specified, "default" is used. In this case,
6707 high-resolution timer mode on older hardware, and in
6717 in situations with strict latency requirements (where
6738 Extensions (TSX) feature in Intel processors that
6743 on - Enable TSX on the system. Although there are
6746 several previous speculation-related CVEs, and
6750 off - Disable TSX on the system. (Note that this
6758 auto - Disable TSX if X86_BUG_TAA is present,
6763 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
6769 Similar to Micro-architectural Data Sampling (MDS)
6776 In vulnerable processors, the speculatively forwarded
6777 data can be used in a cache side channel attack, to
6784 full - Enable TAA mitigation on vulnerable CPUs
6787 full,nosmt - Enable TAA mitigation and disable SMT on
6790 vulnerable to cross-thread TAA attacks.
6791 off - Unconditionally disable TAA mitigation
6793 On MDS-affected machines, tsx_async_abort=off can be
6795 are mitigated with the same mechanism so in order to disable
6805 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
6811 See also Documentation/input/devices/joystick-parport.rst
6813 udbg-immortal [PPC] When debugging early kernel crashes that
6819 Set number of hash buckets for UDP/UDP-Lite connections
6821 uhci-hcd.ignore_oc=
6823 Some badly-designed motherboards generate lots of
6832 unwind_debug [X86-64]
6840 (default -1 = authorized (same as 1),
6845 [USB] The autosuspend time delay (in seconds) used
6846 for newly-detected USB devices (default 2). This
6855 [USB] Maximum number of bytes to snoop in each URB
6866 [USB] Memory limit (in MB) for buffers allocated by
6874 [USB] Specifies timeout for the initial 64-byte
6875 USB_REQ_GET_DESCRIPTOR request in milliseconds
6881 [USB] A list of quirk entries to augment the built-in
6884 VendorID:ProductID:Flags. The IDs are 4-digit hex
6886 will change the built-in quirk; setting it if it is
6891 a 255-byte read);
6895 Set-Interface requests);
6911 require the interval in microframes (1
6914 (bInterval-1).
6918 variable used in the calculation);
6932 to be disconnected before suspend to
6952 usb-storage.delay_use=
6953 [UMS] The delay in seconds before a new device is
6956 usb-storage.quirks=
6958 override the built-in unusual_devs list. List
6961 and Product ID values (4-digit hex numbers) and
6963 to a common usb-storage quirk flag as follows:
7005 medium is write-protected).
7007 even if the device claims no cache,
7014 1 - undefined instruction events
7015 2 - system calls
7016 4 - invalid data aborts
7017 8 - SIGSEGV faults
7018 16 - SIGBUS faults
7024 nohigh = do not allocate PTE pages in
7034 vdso32= [X86] Control the 32-bit vDSO
7035 vdso32=1: enable 32-bit VDSO
7036 vdso32=0 or vdso32=2: disable 32-bit VDSO
7046 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
7048 vector= [IA-64,SMP]
7080 vga= [BOOT,X86-32] Select a particular video mode
7082 Documentation/admin-guide/svga.rst.
7097 - Disable all of the above options
7118 vsyscall= [X86-64]
7121 code). Most statically-linked binaries and older
7145 see VGA-softcursor.txt. Default: 2 = underline.
7150 This is a 16-member array composed of values
7151 ranging from 0-255.
7156 This is a 16-member array composed of values
7157 ranging from 0-255.
7162 This is a 16-member array composed of values
7163 ranging from 0-255.
7168 Set system-wide default UTF-8 mode for all tty's.
7169 Default is 1, i.e. UTF-8 mode is enabled for all
7174 Format=<-1|0|1>
7175 Set system-wide default for whether a cursor
7176 is shown on new VTs. Default is -1,
7181 vt.italic= [VT] Default color for italic text; 0-15.
7184 vt.underline= [VT] Default color for underlined text; 0-15.
7188 see Documentation/watchdog/watchdog-parameters.rst
7189 or other driver-specific files in the
7195 threshold in seconds. The soft lockup detector
7202 to use in unbound workqueues.
7203 Format: <cpu-list>
7212 duration in seconds. The default value is 30 and
7217 Per-cpu work items which run for longer than this
7220 them from noticeably delaying other per-cpu work
7229 Per-cpu workqueues are generally preferred because
7231 locality; unfortunately, per-cpu workqueues tend to
7234 Enabling this makes the per-cpu workqueues which
7247 information, see the Affinity Scopes section in
7248 Documentation/core-api/workqueue.rst.
7258 on the local CPU. This guarantee is no longer true
7261 forces round-robin CPU selection to flush out
7269 on - Enable writecombine, use WUC for ioremap_wc()
7270 off - Disable writecombine, use SUC for ioremap_wc()
7272 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
7276 xen_512gb_limit [KNL,X86-64,XEN]
7286 ide-disks -- unplug primary master IDE devices
7287 aux-ide-disks -- unplug non-primary-master IDE devices
7288 nics -- unplug network devices
7289 all -- unplug all emulated devices (NICs and IDE disks)
7290 unnecessary -- unplugging emulated devices is
7293 never -- do not unplug even if version check succeeds
7301 Select whether to always use non-faulting (safe) MSR
7312 run as generic HVM guest with no PV drivers.
7326 xen_timer_slop= [X86-64,XEN]
7327 Set the timer slop (in nanoseconds) for the virtual Xen
7334 The time (in seconds) to wait before giving up to boot
7335 in case initial ballooning fails to free enough memory.
7341 How long to delay EOI handling in case of event
7351 preferred over the 2-level event handling, as it is
7368 xive.store-eoi=off [PPC]
7374 xhci-hcd.quirks [USB,KNL]
7377 consulted in header drivers/usb/host/xhci.h.