Lines Matching +full:allow +full:- +full:set +full:- +full:time
16 force -- enable ACPI if default was off
17 on -- enable ACPI but allow fallback to DT [arm64,riscv64]
18 off -- disable ACPI if default was on
19 noirq -- do not use ACPI for IRQ routing
20 strict -- Be less tolerant of platforms that are not
22 rsdt -- prefer RSDT over (default) XSDT
23 copy_dsdt -- copy DSDT to memory
24 nocmcff -- Disable firmware first mode for corrected
26 source to check if firmware has set the FF flag. This
28 nospcr -- disable console in ACPI SPCR table as
45 If set to vendor, prefer vendor-specific driver
48 If set to video, use the ACPI video.ko driver.
49 If set to native, use the device's native backlight mode.
50 If set to none, disable the ACPI backlight interface.
77 Documentation/firmware-guide/acpi/debug.rst for more information about
135 Format: <byte> or <bitmap-list>
138 Disable auto-serialization of AML methods
141 auto-serialization feature.
149 Disable installation of static SSDTs at early boot time
159 Ignore the ACPI-based watchdog interface (WDAT) and let
180 acpi_osi=! # disable all built-in OS vendor
182 acpi_osi=!! # enable all built-in OS vendor
244 For broken nForce2 BIOS resulting in XT-PIC timer.
253 as soon as the kernel's real-mode entry point is called.
259 on docking. So the default behaviour is to allow resume
270 sci_force_enable causes the kernel to set SCI_EN directly
291 See Documentation/sound/alsa-configuration.rst
294 Allow the default userspace alignment fault handler
298 align_va_addr= [X86-64]
300 allocating a VMA at process creation time. This option
303 CPU-intensive style benchmark, and it can vary highly in
306 32: only for 32-bit processes
307 64: only for 64-bit processes
308 on: enable for both 32- and 64-bit processes
309 off: disable for both 32- and 64-bit processes
319 Allow execve() of 32-bit applications and setting of the
321 subset of the CPUs support 32-bit EL0. When this
322 parameter is present, the set of CPUs supporting 32-bit
324 and hot-unplug operations may be restricted.
326 See Documentation/arch/arm64/asymmetric-32bit.rst for more
329 amd_iommu= [HW,X86-64]
332 fullflush - Deprecated, equivalent to iommu.strict=1
333 off - do not initialize any AMD IOMMU found in
335 force_isolation - Force device isolation for all
340 force_enable - Force enable the IOMMU on platforms known
343 pgtbl_v1 - Use v1 page table for DMA-API (Default).
344 pgtbl_v2 - Use v2 page table for DMA-API.
345 irtcachedis - Disable Interrupt Remapping Table (IRT) caching.
346 nohugepages - Limit page-sizes used for v1 page-tables
348 v2_pgsizes_only - Limit page-sizes used for v1 page-tables
352 amd_iommu_dump= [HW,X86-64]
358 amd_iommu_intr= [HW,X86-64]
361 legacy - Use legacy interrupt remapping mode.
362 vapic - Use virtual APIC mode, which allows IOMMU
364 This mode requires kvm-amd.avic=1.
393 Disable amd-pstate preferred core.
406 Power management functions (SPARCstation-4/5 + deriv.)
408 Disable APC CPU standby support. SPARCstation-Fox does
409 not play well with APC CPU idle - disable it if you have
412 apic [APIC,X86-64] Use IO-APIC. Default.
418 when initialising the APIC and IO-APIC components.
439 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
442 0 -- disable.
443 1 -- enable.
444 Default value is set via kernel config option.
446 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
459 Set instructions support
482 atkbd.set= [HW] Select keyboard code set
494 audit= [KNL] Enable the audit sub-system
496 0 | off - kernel audit is disabled and can not be
498 unset - kernel audit is initialized but disabled and
500 1 | on - kernel audit is initialized and partially
506 audit_backlog_limit= [KNL] Set the audit queue size limit.
513 0 - Disable the BAU.
514 1 - Enable the BAU.
515 unset - Disable the BAU.
537 for writing, i.e., allow / disallow writes that bypass
554 See Documentation/block/cmdline-partition.rst
568 See Documentation/admin-guide/bootconfig.rst
573 bttv.pll= See Documentation/admin-guide/media/bttv.rst
578 at a time.
582 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
590 [NET] Specifies amount of time (in seconds) that
601 inclusive. See arch/mips/include/asm/pgtable-bits.h
611 - foo isn't auto-mounted if you mount all cgroups in
613 - foo isn't visible as an individually mountable
615 - if foo is an optional feature then the feature is
621 Specifying "pressure" disables per-cgroup pressure
639 nosocket -- Disable socket memory accounting.
640 nokmem -- Disable kernel memory accounting.
641 nobpf -- Disable BPF memory accounting.
643 checkreqprot= [SELINUX] Set initial checkreqprot flag value.
646 0 -- check protection applied by kernel (includes
648 1 -- check protection requested by application.
649 Default value is set via a kernel config option.
660 numbers X. Note the Linux-specific bits are not necessarily
661 stable over kernel options, but the vendor-specific
681 force such clocks to be always-on nor does it reserve
685 information, see Documentation/driver-api/clk.rst.
687 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
704 [X86-32] pit,hpet,tsc;
711 [X86-64] hpet,tsc
717 architected timer so that code using WFE-based polling
731 clocksource-wdtest.holdoff= [KNL]
732 Set the time in seconds that the clocksource
737 cma=nn[MG]@[start[MG][-end[MG]]]
748 Sets the size of kernel per-numa memory area for
750 per-numa CMA altogether. And If this option is not
752 With per-numa CMA enabled, DMA users on node nid will
777 allocations, by default set to 256K.
779 com20020= [HW,NET] ARCnet - COM20020 chipset
783 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
787 ARCnet - COM90xx chipset (memory-mapped buffers)
795 When set to true, drop data on the 3215 console when
800 This leads to a much faster boot time when a 3270
816 See Documentation/admin-guide/serial-console.rst for more
831 $ ls -d /sys/bus/serial-base/devices/*:*.*/tty/*
832 /sys/bus/serial-base/devices/00:04:0.0/tty/ttyS0
845 Start an early, polled-mode console on the 8250/16550
848 MMIO inter-register address stride is either 8-bit
849 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
853 the h/w is not re-initialized.
873 "[time stamp] text\n" format (time stamp may not be
877 Switch to syslog format: "<%u>[time stamp] text\n"
880 syscall, or to executing "dmesg -S --raw" or to reading
897 1: enable debugging at boot time
904 disable the cpuidle sub-system
910 disable the cpufreq sub-system
918 [X86,EARLY] Delay for N microsec between assert and de-assert
935 running the panic notifiers could allow collecting
939 like Hyper-V, PowerPC (fadump) and AMD SEV-SNP.
947 [KNL, X86-64, ARM64, RISCV, LoongArch] Select a region
950 See Documentation/admin-guide/kdump/kdump.rst for further details.
955 start-[end] where start and end are both
957 Documentation/admin-guide/kdump/kdump.rst for an example.
960 [KNL, X86-64, ARM64, RISCV, LoongArch] range could be
962 Allow kernel to allocate physical memory region from top,
968 [KNL, X86-64, ARM64, RISCV, LoongArch] range under 4G.
974 for 32-bit devices won't run out. Kernel would try to allocate
977 --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
978 --> arm64: 128MiB
979 --> riscv: 128MiB
980 --> loongarch: 128MiB
988 [KNL] Disable crypto self-tests
996 csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
1011 See also Documentation/input/devices/joystick-parport.rst
1024 [KNL] verbose locking self-tests
1027 self-tests.
1029 (no extra messages), setting it to -1 (all bits set)
1030 will print _a_lot_ more information - normally only
1036 [KNL,EARLY] When CONFIG_DEBUG_PAGEALLOC is set, this
1055 [KNL,EARLY] When CONFIG_DEBUG_PAGEALLOC is set, this parameter
1056 enables the feature at boot time. By default, it is
1065 Format: { on, no-mount, off }
1067 no-mount:
1072 get a -EPERM as result when trying to register files
1076 Default value is set in build-time with a kernel configuration.
1088 Documentation/admin-guide/mm/hugetlbpage.rst.
1092 [KNL] Debugging option to set a timeout in seconds for
1096 of 0 will timeout at the end of initcalls. If the time
1102 delayacct [KNL] Enable per-task delay accounting
1119 [HW] Allow controlling fans only if SYS_ADMIN
1120 capability is set.
1141 Set number of hash buckets for dentry cache.
1188 entries for DMA-API debugging code. One entry is
1189 required per DMA-API allocation. Use this if the
1190 DMA-API debugging code disables itself because the
1194 With this option the DMA-API debugging driver
1195 filter feature can be enabled at boot time. Just
1203 vulnerability which may allow userspace to infer
1211 This parameter overrides the compile time default set
1218 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
1232 An EDID data set will only be used for a particular
1235 data set by separating the files with a comma. An EDID
1236 data set with no connector name will be used for
1243 Control how the dt_cpu_ftrs device-tree binding is
1253 what data is available or for reverse-engineering.
1257 Enable debug messages at boot time. See
1258 Documentation/admin-guide/dynamic-debug-howto.rst
1269 determined by stdout-path property in device tree's
1274 Start an early, polled-mode console on a Cadence
1285 Start an early, polled-mode console on the 8250/16550
1287 MMIO inter-register address stride is either 8-bit
1288 (mmio) or 32-bit (mmio32 or mmio32be).
1293 the uart clock frequency; if unspecified, it is set
1298 Start an early, polled-mode console on a pl011 serial
1302 the driver will use only 32-bit accessors to read/write
1311 Start an early, polled-mode console on a meson serial
1317 Start an early, polled-mode console on an msm serial
1323 Start an early, polled-mode console on an msm serial
1329 Start an early, polled-mode console on a serial port
1335 Start an early, polled-mode console on a serial port
1341 Use RISC-V SBI (Supervisor Binary Interface) for early
1359 Start an early, polled-mode console on a lantiq serial
1373 Start an early, polled-mode, output-only console on the
1378 Start an early, polled-mode console on the
1384 Start an early, polled-mode console on a Qualcomm
1392 coherent non-x86 systems that use system memory for
1426 be used at a time.
1482 no_disable_early_pci_dma: Leave the busmaster bit set
1495 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1501 ekgdboc= [X86,KGDB,EARLY] Allow early kernel console debugging
1512 elanfreq= [X86-32]
1520 See Documentation/admin-guide/kdump/kdump.rst for details.
1531 The kernel tries to set a reasonable default.
1533 enforcing= [SELINUX] Set initial enforcing status.
1536 0 -- permissive (log only, no denials).
1537 1 -- enforcing (deny and log).
1570 See also Documentation/fault-injection/.
1574 See Documentation/admin-guide/sysctl/net.rst for
1578 See Documentation/admin-guide/blockdev/floppy.rst.
1580 forcepae [X86-32]
1587 fred= [X86-64]
1594 [FTRACE] will set and start the specified tracer
1638 ftrace_filter=[function-list]
1640 tracer at boot up. function-list is a comma-separated
1642 time by the set_ftrace_filter file in the debugfs
1645 ftrace_notrace=[function-list]
1647 function-list. This list can be changed at run time
1651 ftrace_graph_filter=[function-list]
1654 function-list is a comma-separated list of functions
1655 that can be changed at run time by the
1658 ftrace_graph_notrace=[function-list]
1660 function-list. This list is a comma-separated list of
1661 functions that can be changed at run time by the
1667 can be changed at run time by the max_graph_depth file
1680 off -- Don't create device links from firmware info.
1681 permissive -- Create device links from firmware info
1684 on -- Create device links from firmware info and use it
1686 rpm -- Like "on", but also use to order runtime PM.
1699 strict -- Default. Continue waiting on consumers to
1701 timeout -- Give up waiting on consumers and call
1711 See also Documentation/input/devices/joystick-parport.rst
1715 gart_fix_e820= [X86-64,EARLY] disable the fix e820 for K8 GART
1741 gcov_persist= [GCOV] When non-zero (default), profiling data for
1745 debugfs files are removed at module unload time.
1751 gpio-mockup.gpio_mockup_ranges
1754 gpio-mockup.gpio_mockup_named_lines
1786 against bounds-checking flaws in the kernel's
1794 [KNL] Should the hard-lockup detector generate
1800 for 64-bit NUMA, off otherwise.
1808 corresponding firmware-first mode error processing
1817 (that will set all pages holding image data
1818 during restoration read-only).
1842 hostname= [KNL,EARLY] Set the hostname (aka UTS nodename).
1846 Using this parameter to set the hostname makes it
1847 possible to ensure the hostname is correctly set before
1850 has been explicitly set, resulting in the calling
1855 hpet= [X86-32,HPET] option to control HPET usage
1859 force: allow force enabled of undocumented chips (ICH4,
1863 hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET
1864 registers. Default set by CONFIG_HPET_MMAP_DEFAULT.
1872 number of pages to allocate per-node can be specified.
1873 See also Documentation/admin-guide/mm/hugetlbpage.rst.
1884 Documentation/admin-guide/mm/hugetlbpage.rst.
1890 used to improve system bootup time when allocating
1894 Note that this parameter only applies to non-gigantic huge pages.
1904 boot-time allocation of gigantic hugepages is skipped.
1939 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1945 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1951 which allow the hypervisor to 'idle' the guest
1967 Set device-properties for ACPI-enumerated I2C-attached
1968 touchscreen, to e.g. fix coordinates of upside-down
1976 Omit "=<val>" entirely Set a boolean device-property
1977 Unsigned number Set a u32 device-property
1978 Anything else Set a string device-property
1981 i2c_touchscreen_props=GDIX1001:touchscreen-inverted-x:
1982 touchscreen-inverted-y
1984 i2c_touchscreen_props=MSSL1680:touchscreen-size-x=1920:
1985 touchscreen-size-y=1080:touchscreen-inverted-y:
1986 firmware-name=gsl1680-vendor-model.fw:silead,home-button
1991 (disabled by default, and as a pre-condition
1993 i8042.direct [HW] Put keyboard port into non-translated mode
2007 suspend-to-ram transitions, only during s2r
2017 [HW] Allow deferred probing upon i8042 probe errors
2023 set the brightness of the panel backlight. Normally a
2026 to maximum brightness. If this parameter is set to 0
2028 is set to 1, a brightness value of 0 sets the backlight
2031 -1 -- never invert brightness
2032 0 -- machine default
2033 1 -- force brightness inversion
2035 ia32_emulation= [X86-64]
2037 When true, allows loading 32-bit programs and executing 32-bit
2039 boot time. When false, unconditionally disables IA32 emulation.
2062 idle=nomwait: Disable mwait for CPU C-states
2066 Allow force disabling of Shared Virtual Memory (SVA)
2067 support for the idxd driver. By default it is set to
2072 Allow override of default traffic class configuration
2073 for the device. By default it is set to false (0).
2082 of an ELF file header flag individually set by each
2090 legacy only accept legacy-NaN binaries, if supported
2092 2008 only accept 2008-NaN binaries, if supported
2103 'relaxed' straps the emulator for both legacy-NaN and
2104 2008-NaN, whereas 'strict' enables legacy-NaN only on
2113 Ignore loglevel setting - this will print /all/
2125 Set number of hash buckets for inode cache.
2154 mode bit set by either the effective uid (euid=0) or
2180 Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
2181 "ima-sigv2" }
2182 Default: "ima-ng"
2190 Set the minimal file size for using asynchronous hash.
2199 Set hashing buffer size. Default: 4k.
2215 stuff: Deploy RSB-fill mitigation when retpoline is
2220 Documentation/admin-guide/hw-vuln/indirect-target-selection.rst
2231 initcall_blacklist= [KNL] Do not execute a comma-separated list of
2232 initcall functions. Useful for debugging built-in
2259 Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON.
2263 Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON.
2277 0 -- basic integrity auditing messages. (Default)
2278 1 -- additional integrity auditing messages.
2306 could harm performance of some high-throughput
2315 1 to 9 specify maximum depth of C-state.
2324 algorithms for p-state selection. There are two
2325 P-state selection algorithms provided by
2328 on whether or not the hardware managed P-states
2335 used along with the hardware-managed P-states (HWP)
2339 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2340 instead of acpi-cpufreq may disable platform features, such
2342 P-States information being indicated to OSPM and therefore
2345 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2358 Allow per-logical-CPU P-State performance control limits using
2361 Do not enable capacity-aware scheduling (CAS) on
2364 intremap= [X86-64,Intel-IOMMU,EARLY]
2369 BIOS x2APIC opt-out request will be ignored
2412 AMD Gart HW IOMMU-specific options:
2415 Set the size of the remapping area in bytes.
2431 Do scatter-gather (SG) merging. Implies "force"
2435 Don't do scatter-gather (SG) merging.
2448 0 - Try to allocate a 32-bit DMA address first, before
2450 1 - Allocate directly from the full usable range,
2452 greater than 32-bit addressing.
2456 0 - Lazy mode.
2462 1 - Strict mode.
2465 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2467 legacy driver-specific options takes precedence.
2472 0 - Use IOMMU translation for DMA.
2473 1 - Bypass the IOMMU for DMA.
2474 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2476 io7= [HW] IO7 for Marvel-based Alpha systems
2491 See Documentation/admin-guide/nfs/nfsroot.rst.
2508 irqaffinity= [SMP] Set the default irq affinity mask
2527 Enables support for pseudo-NMIs in the kernel. This
2545 isolcpus= [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
2546 [Deprecated - use cpusets instead]
2547 Format: [flag-list,]<cpu-list>
2575 move in and out of an isolated set anytime.
2580 "number of CPUs in system - 1".
2606 The format of <cpu-list> is described above.
2610 ivrs_ioapic [HW,X86-64]
2611 Provide an override to the IOAPIC-ID<->DEVICE-ID
2615 For example, to map IOAPIC-ID decimal 10 to
2621 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2624 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2628 ivrs_hpet [HW,X86-64]
2629 Provide an override to the HPET-ID<->DEVICE-ID
2633 For example, to map HPET-ID decimal 10 to
2639 * To map HPET-ID decimal 0 to PCI device 00:14.0
2642 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2646 ivrs_acpihid [HW,X86-64]
2647 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2651 For example, to map UART-HID:UID AMD0020:0 to
2657 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2660 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2684 the kernel for non-movable allocations. The requested
2694 subsystem. Note that allocations like PTEs-from-HighMem
2702 for non-movable allocations and remaining memory is used
2713 gdb or control-c on the dbgp connection. When
2714 not using this parameter you use sysrq-g to break into
2719 or a supported polling keyboard driver (non-usb).
2746 Configure the RouterBoard 532 series on-chip
2749 kmemleak= [KNL,EARLY] Boot-time kmemleak enable/disable
2755 kprobe_event=[probe-list]
2756 [FTRACE] Add kprobe events and enable at boot time.
2757 The probe-list is a semicolon delimited list of probe
2775 CONFIG_KUNIT to be set to be fully enabled. The
2787 execution by eliminating the write-protection faults
2793 disabling eager page splitting to allow huge pages to
2814 virtualization on-demand when creating and destroying
2822 is that doing so may interfere with using out-of-tree
2848 [KVM] Controls the time period at which KVM zaps 4KiB pages
2849 back to huge pages. If the value is a non-zero N, KVM will
2854 kvm-amd.nested= [KVM,AMD] Control nested virtualization feature in
2857 kvm-amd.npt= [KVM,AMD] Control KVM's use of Nested Page Tables,
2858 a.k.a. Two-Dimensional Page Tables. Default is 1
2862 kvm-arm.mode=
2868 nvhe: Standard nVHE-based mode, without support for
2875 nested: VHE-based mode with support for nested
2883 command-line.
2887 kvm-arm.vgic_v3_group0_trap=
2888 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-0
2891 kvm-arm.vgic_v3_group1_trap=
2892 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-1
2895 kvm-arm.vgic_v3_common_trap=
2899 kvm-arm.vgic_v4_enable=
2900 [KVM,ARM,EARLY] Allow use of GICv4 for direct
2903 kvm-arm.wfe_trap_policy=
2904 [KVM,ARM] Control when to set WFE instruction trap for
2908 trap: set WFE instruction trap
2912 kvm-arm.wfi_trap_policy=
2913 [KVM,ARM] Control when to set WFI instruction trap for
2917 trap: set WFI instruction trap
2929 kvm-intel.ept= [KVM,Intel] Control KVM's use of Extended Page Tables,
2930 a.k.a. Two-Dimensional Page Tables. Default is 1
2934 kvm-intel.emulate_invalid_guest_state=
2936 state. Ignored if kvm-intel.enable_unrestricted_guest=1,
2942 kvm-intel.flexpriority=
2947 kvm-intel.nested=
2951 kvm-intel.unrestricted_guest=
2957 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2958 CVE-2018-3620.
2969 kvm-intel.vpid= [KVM,Intel] Control KVM's use of Virtual Processor
2989 on - enable the interface for the mitigation
3054 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
3060 lapic [X86-32,APIC,EARLY] Enable the local APIC even if BIOS
3064 value for LAPIC timer one-shot implementation. Default
3084 when set.
3087 libata.force= [LIBATA] Force configurations. The format is a comma-
3099 first fan-out link behind PMP device. It does not
3113 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
3120 * rstonce: only attempt one reset during hot-unplug
3137 * max_trim_128m: Set 128M maximum trim size limit.
3155 * max_sec_128: Set transfer size limit to 128 sectors.
3157 * max_sec_1024: Set or clear transfer size limit to
3160 * max_sec_lba48: Set or clear transfer size limit to
3163 * external: Mark port as external (hotplug-capable).
3196 Enable the kernel lockdown feature. If set to
3197 integrity, kernel features that allow userland to
3198 modify the running kernel are disabled. If set to
3199 confidentiality, kernel features that allow userland
3204 Set the time limit in jiffies for a lock
3217 Specify the number of self-propagating call_rcu()
3218 chains to set up. These are used to ensure that
3220 in progress at any given time. Defaults to 0,
3225 occasional long-duration lock hold time. Defaults
3236 Set the number of locking read-acquisition kthreads.
3237 Defaults to being automatically set based on the
3241 Set the number of locking write-acquisition kthreads.
3244 Set time (s) after boot for CPU-hotplug testing.
3247 Set time (s) between CPU-hotplug operations, or
3248 zero to disable CPU-hotplug testing.
3251 Do periodic testing of real-time lock priority
3256 non-real-time spinlocks, due to their disabling
3257 of preemption. Note that non-realtime mutexes
3264 number of boosts per unit time remains roughly
3270 Set task-shuffle interval (jiffies). Shuffling
3271 tasks allows some CPUs to go into dyntick-idle
3275 Set time (s) after boot system shutdown. This
3276 is useful for hands-off automated testing.
3279 Time (s) between statistics printk()s.
3282 Time (s) to stutter testing, for example,
3295 Run the write-side locktorture kthreads at
3296 sched_set_fifo() real-time priority.
3314 7 (KERN_DEBUG) debug-level messages
3326 logo.nologo [FB] Disables display of the built-in Linux logo.
3344 an IEEE 1284-compliant printer is attached; if
3350 time-consuming boot-time autodetection (up to 250 ms per
3370 Example: machtype=lemote-yeeloong-2f-7inch
3382 (loop.max_loop) unconditionally pre-created at init time. The default
3385 devices can be requested on-demand with the
3386 /dev/loop-control interface.
3388 mce= [X86-{32,64}]
3425 do not opt-in to Local MCE delivery. Use legacy method
3442 sets the time in us to wait for other CPUs on machine
3446 don't overwrite the bios-set CMCI threshold. This boot
3448 threshold set by the bios. Without this option, Linux
3455 force-enable recoverable machine check code paths
3461 See Documentation/admin-guide/md.rst.
3468 Control mitigation for the Micro-architectural Data
3483 full - Enable MDS mitigation on vulnerable CPUs
3484 full,nosmt - Enable MDS mitigation and disable
3486 off - Unconditionally disable MDS mitigation
3488 On TAA-affected machines, mds=off can be prevented by
3497 For details see: Documentation/admin-guide/hw-vuln/mds.rst
3499 mem=nn[KMG] [HEXAGON,EARLY] Set the memory size.
3512 [ARC,MICROBLAZE] - the limit applies only to low memory,
3515 [ARM64] - only limits memory covered by the linear
3523 Note that this only takes effects during boot time since
3528 [ARM,MIPS,EARLY] - override the memory layout
3535 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
3541 [KNL,SH] Allow user to override the default size for
3542 per-device physically contiguous DMA buffers.
3545 [KNL] Set the initial state for the memory hotplug
3547 set according to the
3550 See Documentation/admin-guide/mm/memory-hotplug.rst.
3575 Example: Exclude memory from 0x18690000-0x1869ffff
3589 memmap=<size>%<offset>-<oldtype>+<newtype>
3591 from <oldtype> to <newtype>. If "-<oldtype>" is left
3606 repeatable BIOS-originated corruption always
3628 hotadded memory which will allow to hotadd a
3645 pattern from a given set of patterns. Memtest
3650 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
3656 Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
3660 s2idle - Suspend-To-Idle
3661 shallow - Power-On Suspend or equivalent (if supported)
3662 deep - Suspend-To-RAM or equivalent (if supported)
3663 See Documentation/admin-guide/pm/sleep-states.rst.
3665 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
3681 0 - The attached screen is the 3.5" TFT
3682 1 - The attached screen is the 7" TFT
3683 2 - The VGA Shield is attached (1024x768)
3687 b - Enable backlight. The TFT backlight pin will be
3691 c - Enable the s3c camera interface.
3692 t - Reserved for enabling touchscreen support. The
3696 https://repo.or.cz/w/linux-2.6/mini2440.git
3700 CPU vulnerabilities. This is a set of curated,
3701 arch-independent options, each of which is an
3702 aggregation of existing arch-specific options.
3732 ssbd=force-off [ARM64]
3745 have other ways of avoiding SMT-based attacks.
3759 [KNL,EARLY] When CONFIG_DEBUG_MEMORY_INIT is set, this
3780 full - Enable mitigation on vulnerable CPUs
3782 full,nosmt - Enable mitigation and disable SMT on
3785 off - Unconditionally disable mitigation
3798 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3808 [KNL] When set to true, modules will use async probing
3817 [KNL] When CONFIG_MODULE_DEBUG_AUTOLOAD_DUPS is set,
3820 if MODULE_DEBUG_AUTOLOAD_DUPS_TRACE is set, WARN_ON()s
3823 [KNL] When CONFIG_MODULE_SIG is set, this means that
3825 Note that if CONFIG_MODULE_SIG_FORCE is set, that
3828 module_blacklist= [KNL] Do not load a comma-separated list of
3832 [MOUSE] Maximum time between finger touching and
3853 movable_node [KNL,EARLY] Boot-time switch to make hotplugable memory
3860 Format: <name>,<region-number>,<size>,<offset>
3863 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3874 registers at boot time.
3891 Set to 2 or more if your graphical card needs more.
3895 at a time.
3902 something different and driver-specific.
3907 [NET] Specifies amount of time (in seconds) that
3926 [NFSv4] set the total number of threads that the
3931 [NFS] set the TCP port on which the NFSv4 callback
3942 [NFS] enable 64-bit inode numbers.
3943 If zero, the NFS client will fake up a 32-bit inode
3945 of returning the full 64-bit number.
3946 The default is to return 64-bit inode numbers.
3949 [NFS] set the maximum lifetime for idmapper cache
3968 [NFSv4] When set to the default of '1', this option
3978 To turn off this behaviour, set the value to '0'.
3981 [NFS4] Specify an additional fixed unique ident-
3984 UUID that is generated at system install time.
3993 attempting to recover these locks, then set this
4011 whatever value is the default set by the layout
4012 driver. A non-zero value sets the minimum interval
4016 [NFSv4.2] When set to 1, the server will support
4017 server-to-server copies for which this server is
4021 [NFSv4] When set to the default of '1', the NFSv4
4029 server-to-server copy, knfsd temporarily mounts
4036 See Documentation/admin-guide/nfs/nfsroot.rst.
4038 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
4039 See Documentation/admin-guide/nfs/nfsroot.rst.
4042 See Documentation/admin-guide/nfs/nfsroot.rst.
4046 NMI stack-backtrace request.
4055 0 - turn hardlockup detector in nmi_watchdog off
4056 1 - turn hardlockup detector in nmi_watchdog on
4057 rNNN - configure the watchdog with raw perf event 0xNNN
4061 watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set)
4070 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
4074 no4lvl [RISCV,EARLY] Disable 4-level and 5-level paging modes.
4075 Forces kernel to use 3-level paging instead.
4077 no5lvl [X86-64,RISCV,EARLY] Disable 5-level paging mode. Forces
4078 kernel to use 4-level paging instead.
4085 noapictimer [APIC,X86] Don't set up the APIC timer
4109 nodsp [SH] Disable hardware DSP at boot time.
4113 no_entry_flush [PPC,EARLY] Don't flush the L1-D cache when entering the kernel.
4115 noexec32 [X86-64]
4116 This affects only 32-bit executables.
4117 noexec32=on: enable non-executable mappings (default)
4119 noexec32=off: disable non-executable mappings
4126 nofpu [MIPS,SH] Disable hardware FPU at boot time.
4130 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4132 legacy floating-point registers on task switch.
4145 compared. However, if this command-line option is
4174 In kernels built with CONFIG_NO_HZ_FULL=y, set
4188 nointremap [X86-64,Intel-IOMMU,EARLY] Do not enable interrupt
4190 [Deprecated - use intremap=off]
4196 noirqdebug [X86-32] Disables the code which attempts to detect and
4202 When CONFIG_RANDOMIZE_BASE is set, this disables
4206 no-kvmapf [X86,KVM,EARLY] Disable paravirtualized asynchronous page
4209 no-kvmclock [X86,KVM,EARLY] Disable paravirtualized KVM clock driver
4211 nolapic [X86-32,APIC,EARLY] Do not enable or use the local APIC.
4213 nolapic_timer [X86-32,APIC,EARLY] Do not use the local APIC timer.
4215 nomce [X86-32] Disable Machine Check Exception
4217 nomfgpt [X86-32] Disable Multi-Function General Purpose
4223 not load if they could possibly displace the pre-
4226 perform display-mode changes or accelerated rendering.
4239 nopcid [X86-64,EARLY] Disable the PCID cpu feature.
4244 nopti [X86-64,EARLY]
4254 which allow the hypervisor to 'idle' the guest on lock
4260 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
4266 no-scroll [VGA] Disables scrollback.
4267 This is required for the Braillex ib80-piezo Braille
4270 nosgx [X86-64,SGX,EARLY] Disables Intel SGX kernel support.
4290 nosoftlockup [KNL] Disable the soft-lockup detector.
4296 nospectre_bhb [ARM64,EARLY] Disable all mitigations for Spectre-BHB (branch
4297 history injection) vulnerability. System may allow data leaks
4306 prediction) vulnerability. System may allow data
4309 no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,LOONGARCH,EARLY]
4310 Disable paravirtualized steal time accounting. steal time
4316 timer IRQ sources, i.e., the IO-APIC timer. This can
4321 [PPC,EARLY] Don't flush the L1-D cache after accessing user data.
4332 is set.
4334 no-vmw-sched-clock
4339 soft-lockup and NMI watchdog (hard-lockup).
4343 nox2apic [X86-64,APIC,EARLY] Do not enable x2APIC mode.
4346 LEGACY_XAPIC_DISABLED bit set in the
4351 enabling legacy floating-point and sse state.
4373 n. So during boot up some boot time memory for per-cpu
4374 variables need be pre-allocated for later physical cpu
4380 Disable NUMA, Only set up a single NUMA node
4401 soft-reserved memory partitioning.
4409 This can be set from sysctl after boot.
4410 See Documentation/admin-guide/sysctl/vm.rst for details.
4413 See Documentation/core-api/debugging-via-ohci1394.rst for more
4420 waiting for the ACK, so if this is set too high
4428 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
4432 boundary - index of last SLC block on Flex-OneNAND.
4434 lock - Configure if Flex-OneNAND boundary should be locked.
4453 page_owner= [KNL,EARLY] Boot-time page_owner enabling option.
4459 page_poison= [KNL,EARLY] Boot-time parameter changing the state of
4480 Hexadecimal bitmask representing the set of TAINT flags
4482 called with any of the flags in this set.
4486 bitmask set on panic_on_taint.
4487 See Documentation/admin-guide/tainted-kernels.rst for
4540 Set to non-zero to probe primary and secondary ISA
4546 Set to non-zero if a chip is present that snoops speed
4551 Set to 1, 2, or 3 for HT 6560A on the primary channel,
4557 Set to 1, 2, or 3 for HT 6560B on the primary channel,
4563 IORDY enable mask. Set individual bits to allow IORDY
4575 Set to 1, 2, or 3 for Opti 82c611A on the primary
4581 Set to 1, 2, or 3 for Opti 82c465MV on the primary
4587 PIO mode mask for autospeed devices. Set individual
4588 bits to allow the use of the respective PIO modes.
4594 Set to non-zero to probe tertiary and further ISA
4610 Set to non-zero to probe QDI controllers. By default
4611 set to 1 if CONFIG_PATA_QDI_MODULE, 0 otherwise.
4615 Set to non-zero to probe Winbond controllers. Use
4618 By default set to 1 if CONFIG_PATA_WINBOND_VLB_MODULE,
4623 Supported PIO mode mask. Set individual bits to allow
4638 or a set of devices (<pci_dev>). These are
4662 bios [X86-32] force use of PCI BIOS, don't access
4664 has a non-standard PCI host bridge.
4665 nobios [X86-32] disallow use of PCI BIOS, only direct
4671 data in IO port 0xCFC, both 32-bit).
4673 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
4674 the function, IO port 0xCFA, also 8-bit, sets
4676 through ports 0xC000-0xCFFF).
4683 root domains (aka PCI segments, in ACPI-speak).
4691 disable the use of MSI interrupts system-wide.
4696 primary IO-APIC for bridges that cannot disable
4703 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
4720 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
4727 F0000h-100000h range.
4732 assign-busses [X86] Always assign all PCI bus
4753 <linux-pci@vger.kernel.org>.
4757 a bug to <linux-pci@vger.kernel.org>.
4769 bfsort Sort PCI devices into breadth-first order.
4772 nobfsort Don't sort PCI devices into breadth-first order.
4774 tuning and use the BIOS-configured MPS defaults.
4775 pcie_bus_safe Set every device's MPS to the largest value
4777 pcie_bus_perf Set device MPS to the largest allowable MPS
4778 based on its parent bus. Also set MRRS (Max
4782 pcie_bus_peer2peer Set every device's MPS to 128B, which
4784 configuration allows peer-to-peer DMA between
4787 that hot-added devices will work.
4802 A PCI-PCI bridge can be specified if resource
4808 for 4096-byte alignment.
4810 end-to-end CRC checking). Only effective if
4841 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4848 can resize a BAR to allow access to all VRAM.
4857 allow P2P traffic between devices through
4872 bit-0 : ACS Source Validation
4873 bit-1 : ACS Translation Blocking
4874 bit-2 : ACS P2P Request Redirect
4875 bit-3 : ACS P2P Completion Redirect
4876 bit-4 : ACS Upstream Forwarding
4877 bit-5 : ACS P2P Egress Control
4878 bit-6 : ACS Direct Translated P2P
4888 Validation unchanged from whatever power-up
4889 or firmware set it to.
4900 system-wide.
4914 dpc-native Use native PCIe service for DPC only. May
4931 Keep all power-domains already enabled by bootloader on,
4937 boot time.
4949 pirq= [SMP,APIC] Manual mp-table setup
4950 See Documentation/arch/x86/i386/IO-APIC.rst.
4954 See also Documentation/admin-guide/parport.rst.
4964 cleared). If a number is given, then MMCR1 is set to
4973 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4982 { on | off | curr | res | no-curr | no-res }
5006 Set the number of possible CPUs, overriding the
5027 none - Limited to cond_resched() calls
5028 voluntary - Limited to cond_resched() and might_sleep() calls
5029 full - Any section that isn't explicitly preempt disabled
5033 lazy - Scheduler controlled. Similar to full but instead
5035 one HZ tick time to yield itself before the
5039 print-fatal-signals=
5045 coredump - etc.
5048 you might want to try "ulimit -i unlimited".
5060 or lockdep-detected issues (only if lock debug is on).
5068 Allows storing messages from non-panic CPUs into
5070 flushed to consoles by the panic-CPU on
5071 a best-effort basis.
5077 on - unlimited logging to /dev/kmsg from userspace
5078 off - logging to /dev/kmsg disabled
5079 ratelimit - ratelimit the logging
5082 printk.time= Show timing data prefixed to each printk message line
5088 overridden without restrictions. This option may be set to
5090 - 'always': traditional behavior always allows mem overrides.
5091 - 'ptrace': only allow mem overrides for active ptracers.
5092 - 'never': never allow mem overrides.
5096 Limit processor to maximum C-state
5100 Ignore the _CST method to determine C-states,
5107 Param: "schedule" - profile schedule points.
5108 Param: "kvm" - profile VM exits.
5109 Param: <number> - step/bucket size as a power of 2 for
5110 statistical time based profiling.
5127 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
5133 [HW,MOUSE] Set desired mouse resolution, in dpi.
5140 pti= [X86-64] Control Page Table Isolation of user and
5145 on - unconditionally enable
5146 off - unconditionally disable
5147 auto - kernel detects whether your CPU model is
5153 [KNL] Number of legacy pty's. Overwrites compiled-in
5165 See Documentation/admin-guide/md.rst.
5168 See Documentation/admin-guide/blockdev/ramdisk.rst.
5187 cross-syscall address exposures. This is only
5193 ras=option[,option,...] [KNL] RAS-specific options
5199 rcu_nocbs[=cpu-list]
5204 enable the no-callback CPU mode, which prevents
5209 "p" for RCU-preempt, "s" for RCU-sched, and "g"
5213 and real-time workloads. It can also improve
5217 list of CPUs is set to no-callback mode from boot.
5220 arguments are omitted, no CPU will be set to
5221 no-callback mode from boot but the mode may be
5232 This improves the real-time response for the
5239 Set maximum number of finished RCU callbacks to
5243 Do only a one-line RCU CPU stall warning when
5244 there is an ongoing too-long CSD-lock wait.
5250 If triggered before the RCU grace-period machinery
5259 Set the number of jiffies to delay each step of
5260 RCU grace-period cleanup.
5263 Set the number of jiffies to delay each step of
5264 RCU grace-period initialization.
5267 Set the number of jiffies to delay each step of
5268 RCU grace-period pre-initialization, that is,
5269 the propagation of recent CPU-hotplug changes up
5273 Set delay from grace-period initialization to
5279 Set delay between subsequent attempts to force
5284 Set required age in jiffies for a
5286 soliciting quiescent-state help from
5293 rcutree.jiffies_to_sched_qs. Any attempt to set
5298 Set the SCHED_FIFO priority of the RCU per-CPU
5301 and for the RCU grace-period kthreads (rcu_bh,
5303 set, valid values are 1-99 and the default is 1
5304 (the least-favored priority). Otherwise, when
5305 RCU_BOOST is not set, valid values are 0-99 and
5306 the default is zero (non-realtime operation).
5307 When RCU_NOCB_CPU is set, also adjust the
5311 On callback-offloaded (rcu_nocbs) CPUs,
5314 use of the ->nocb_bypass list. However, in the
5315 common non-flooded case, RCU queues directly to
5316 the main ->cblist in order to avoid the extra
5317 overhead of the ->nocb_bypass list and its lock.
5319 a single jiffy, RCU pre-queues the callbacks into
5320 the ->nocb_bypass queue. The definition of "too
5324 On callback-offloaded (rcu_nocbs) CPUs, avoid
5332 Set threshold of queued RCU callbacks beyond which
5336 Set threshold of queued RCU callbacks below which
5337 batch limiting is re-enabled.
5340 Set threshold of queued RCU callbacks beyond which
5341 RCU's force-quiescent-state scan will aggressively
5344 Set to less than zero to make this be set based
5345 on rcutree.qhimark at boot time and to zero to
5349 Set the page-cache refill delay (in milliseconds)
5350 in response to low-memory conditions. The range
5354 Set the shift-right count to use to compute
5355 the callback-invocation batch limit bl from
5360 order to allow the CPU to do other work.
5362 Please note that this callback-invocation batch
5363 limit applies only to non-offloaded callback
5372 cache-to-cache transfer latencies.
5378 and for NUMA systems with large remote-access
5391 Set the number of NOCB callback kthreads in
5394 the wakeup overhead on the global grace-period
5396 each group's NOCB grace-period kthread.
5399 Cause the grace-period kthread to get an extra
5401 it should at force-quiescent-state time.
5406 Limit the time spend invoking a batch of RCU
5414 this specifies an rcu_read_unlock()-time delay
5418 of RCU-protected pointers after the relevant
5427 If set to zero, move all RCU_SOFTIRQ processing to
5428 per-CPU rcuc kthreads. Defaults to a non-zero
5457 grace-period primitives such as call_rcu().
5463 corresponding flavor of rcu_barrier() to allow
5468 grace-period primitives.
5471 Set test-start holdoff period. The purpose of
5486 Set to measure performance of kfree_rcu() flooding.
5489 Test the double-argument variant of kfree_rcu().
5491 rcuscale.kfree_rcu_test_single, both the single-
5492 and double-argument variants are tested.
5495 Test the single-argument variant of kfree_rcu().
5497 rcuscale.kfree_rcu_test_double, both the single-
5498 and double-argument variants are tested.
5511 Set the minimum test run time in seconds. This
5512 does not affect the data-collection interval,
5517 Set number of RCU readers. The value -1 selects
5519 "n" less than -1 selects N-n+1, where N is again
5520 the number of CPUs. For example, -2 selects N
5521 (the number of CPUs), -3 selects N+1, and so on.
5522 A value of "n" less than or equal to -N selects
5526 Set number of RCU writers. The values operate
5535 complete. This is useful for hands-off automated
5542 Write-side holdoff between grace periods,
5547 Additional write-side holdoff between grace
5552 Set duration of force_quiescent_state bursts
5556 Set holdoff time within force_quiescent_state bursts
5560 Set wait time between force_quiescent_state bursts
5565 for RCU grace-period forward-progress testing
5572 Specify the fraction of a CPU-stall-warning
5573 period to do tight-loop forward-progress testing.
5577 forward-progress tests.
5581 need_resched() during tight-loop forward-progress
5585 Use conditional/asynchronous update-side
5586 normal-grace-period primitives, if available.
5589 Use conditional/asynchronous update-side
5590 expedited-grace-period primitives, if available.
5593 Use conditional/asynchronous update-side
5594 normal-grace-period primitives that also take
5599 Use conditional/asynchronous update-side
5600 expedited-grace-period primitives that also take
5624 Use expedited update-side primitives, if available.
5627 Use normal (non-expedited) asynchronous
5628 update-side primitives, if available.
5631 Use polled update-side normal-grace-period
5635 Use polled update-side expedited-grace-period
5639 Use polled update-side normal-grace-period
5644 Use polled update-side expedited-grace-period
5668 Use normal (non-expedited) synchronous
5669 update-side primitives, if available. If all
5673 they are all non-zero.
5681 Leak an RCU-protected pointer out of the reader.
5688 Set callbacks/threads for rcu_barrier() testing.
5691 Set number of concurrent RCU writers. These just
5696 Set number of RCU callback-offload togglers.
5700 Set the delay in milliseconds between successive
5701 callback-offload toggling attempts.
5704 Set number of RCU readers. The value -1 selects
5705 N-1, where N is the number of CPUs. A value
5706 "n" less than -1 selects N-n-2, where N is again
5707 the number of CPUs. For example, -2 selects N
5708 (the number of CPUs), -3 selects N+1, and so on.
5711 Enable debug-object double-call_rcu() testing.
5714 Set time (s) after boot for CPU-hotplug testing.
5717 Set time (jiffies) between CPU-hotplug operations,
5718 or zero to disable CPU-hotplug testing.
5721 Set duration (in milliseconds) of preemptions
5722 by a high-priority FIFO real-time task. Set to
5724 preempt are selected randomly from the set that
5725 are online at a given point in time. Races with
5730 Set interval (in milliseconds, defaulting to one
5731 second) between preemptions by a high-priority
5732 FIFO real-time task. This delay is mediated
5737 The number of times in a given read-then-exit
5738 episode that a set of read-then-exit kthreads
5743 read-then-exit testing episodes.
5747 If there is more than one bit set, the readers
5748 are entered from low-order bit up, and are
5750 0x1 bit is normal readers, 0x2 NMI-safe readers,
5751 and 0x4 light-weight readers.
5754 Set task-shuffle interval (s). Shuffling tasks
5755 allows some CPUs to go into dyntick-idle mode
5759 Set time (s) after boot system shutdown. This
5760 is useful for hands-off automated testing.
5767 Sleep while stalling if set. This will result
5769 any other stall-related activity. Note that
5775 in scheduling-while-atomic splats.
5781 Time to wait (s) after boot before inducing stall.
5784 Disable interrupts while stalling if set, but only
5785 on the first stall in the set.
5794 grace-period kthread to test RCU CPU stall
5800 Time (s) between statistics printk()s.
5803 Time (s) to stutter testing, for example, specifying
5817 Holdoff time (s) from start of test to the start
5818 of RCU priority-boost testing. Defaults to zero,
5825 Test RCU's dyntick-idle handling. See also the
5850 during early boot, that is, during the time
5854 Set timeout for RCU CPU stall warning messages.
5859 Set timeout for expedited RCU CPU stall warning
5880 Use expedited grace-period primitives, for
5884 real-time latency, and degrade energy efficiency.
5888 Use only normal grace-period primitives,
5891 real-time latency, CPU utilization, and
5893 increased grace-period latency. This parameter
5900 only normal grace-period primitives. No effect
5906 post-boot attempt at an expedited RCU grace
5907 period to instead use normal non-expedited
5908 grace-period processing.
5911 Set the maximum number of callbacks present
5916 set to the default value of -1.
5919 Set the minimum number of callback-queuing-time
5920 lock-contention events per jiffy required to
5921 cause the RCU Tasks flavors to switch to per-CPU
5923 when rcupdate.rcu_task_enqueue_lim is set to
5924 the default value of -1.
5927 Set the number of callback queues to use for the
5929 of -1 allows this to be automatically (and
5934 Set time in jiffies during which RCU tasks will
5937 number avoids disturbing real-time workloads,
5942 cancel laziness on that CPU. Use -1 to disable
5948 Set initial timeout in jiffies for RCU task stall
5952 only printed prior to the stall-warning message
5959 Multiplier for time interval between successive
5970 Set timeout in jiffies for RCU task stall
5977 Set timeout in milliseconds RCU Tasks asynchronous
5984 Set timeout in milliseconds RCU Tasks
6000 force - Override the decision by the kernel to hide the
6020 (prefix with 'panic_' to set mode for panic
6036 Set the cold reboot flag
6039 There are some built-in platform specific "quirks"
6040 - you may see: "reboot: <name> series board detected.
6044 built-in quirk table, and use the generic default
6067 Don't set the cold reboot flag
6077 Set test-start holdoff period. The purpose of
6089 Set the number of loops over the synchronization
6092 but the default has already reduced the per-pass
6097 Set number of readers. The default value of -1
6102 Set number of runs, each of which is dumped onto
6106 Set the read-side critical-section duration,
6110 Specify the read-protection implementation to test.
6135 [KNL, SMP] Set scheduler's default relax_domain_level.
6136 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
6166 reservetop= [X86-32,EARLY]
6183 See Documentation/power/swsusp-and-swap-files.rst
6199 AMD-based UNRET and IBPB mitigations alone do not stop
6201 sibling threads. For that reason, STIBP is used on pro-
6205 off - no mitigation
6206 auto - automatically select a migitation
6207 auto,nosmt - automatically select a mitigation,
6211 ibpb - On AMD, mitigate short speculation
6216 ibpb,nosmt - Like "ibpb" above but will disable SMT
6220 unret - Force enable untrained return thunks,
6221 only effective on AMD f15h-f17h based
6223 unret,nosmt - Like unret, but will disable SMT when STIBP
6228 time according to the CPU.
6255 ro [KNL] Mount root device read-only on boot
6258 on Mark read-only kernel memory as read-only (default).
6259 off Leave read-only kernel memory writable for debugging.
6260 full Mark read-only kernel memory and aliases as read-only
6267 debug-uart get routed to the D+ and D- pins of the usb
6273 block/early-lookup.c for details.
6281 rootflags= [KNL] Set root filesystem mount option string
6283 rootfstype= [KNL] Set root filesystem type
6289 rootwait= [KNL] Maximum time (in seconds) to wait for root device
6298 rw [KNL] Mount root device read-write on boot
6303 Set s390 IOTLB flushing mode
6334 [KNL, SMP] Set a decay shift for scheduler thermal
6352 to 10 seconds for built-in smp_call_function()
6359 that requesting even small non-zero numbers of
6366 The default of -1 specifies a number of kthreads
6371 test before initiating CPU-hotplug operations.
6375 CPU-hotplug operations. Specifying zero (which
6376 is the default) disables CPU-hotplug operations.
6382 Non-zero values are useful for automated tests.
6391 to the set of CPUs under test.
6405 "wait" parameter. A value of -1 selects the
6406 default if all other weights are -1. However,
6408 value of -1 will instead select a weight of zero.
6413 non-zero "wait" parameter. See weight_single.
6426 non-zero "wait" parameter. See weight_single
6438 non-zero "wait" parameter. See weight_single
6447 contention on all systems with CONFIG_MAXSMP set.
6449 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
6450 1 -- enable.
6458 selinux= [SELINUX] Disable or enable SELinux at boot time.
6461 0 -- disable.
6462 1 -- enable.
6465 serialnumber [BUGS=X86-32]
6467 sev=option[,option...] [X86-64]
6473 Do not enable SEV-SNP (applies to host/hypervisor
6476 SEV-SNP guests.
6484 to set it to "all" by meaning -- no limit here.
6557 Specify the period of time in milliseconds
6562 of time. Defaults to 5,000 milliseconds, and
6565 using the csdlock_debug- kernel parameter.
6570 system. By default, let CSD-lock acquisition
6572 for this value provides a 5-minute timeout.
6574 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
6575 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
6576 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
6577 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
6578 smsc-ircc2.ircc_irq= [HW] IRQ line
6579 smsc-ircc2.ircc_dma= [HW] DMA channel
6580 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
6585 smt= [KNL,MIPS,S390,EARLY] Set the maximum number of threads
6590 Default: -1 (no limit)
6593 [KNL] Should the soft-lockup detector generate panics.
6596 A value of 1 instructs the soft-lockup detector
6597 to panic the machine when a soft-lockup occurs. It is
6600 respective build-time switch to that functionality.
6603 [KNL] Should the soft-lockup detector generate
6608 See Documentation/admin-guide/laptops/sonypi.rst
6615 on - (default) Enable the HW or SW mitigation as
6618 vmexit - On systems which don't have the HW mitigation
6621 protected from VM-originated BHI attacks, but
6623 off - Disable the mitigation.
6630 on - unconditionally enable, implies
6632 off - unconditionally disable, implies
6634 auto - kernel detects whether your CPU model is
6638 mitigation method at run time according to the
6653 retpoline - replace indirect branches
6654 retpoline,generic - Retpolines
6655 retpoline,lfence - LFENCE; indirect branch
6656 retpoline,amd - alias for retpoline,lfence
6657 eibrs - Enhanced/Auto IBRS
6658 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
6659 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
6660 ibrs - use IBRS to protect kernel
6670 on - Unconditionally enable mitigations. Is
6673 off - Unconditionally disable mitigations. Is
6676 prctl - Indirect branch speculation is enabled,
6682 - Like "prctl" above, but only STIBP is
6688 - Same as "prctl" above, but all seccomp
6693 - Like "seccomp" above, but only STIBP is
6698 auto - Kernel selects the mitigation depending on
6709 off - Disable mitigation
6710 microcode - Enable microcode mitigation only
6711 safe-ret - Enable sw-only safe RET mitigation (default)
6712 ibpb - Enable mitigation by issuing IBPB on
6714 ibpb-vmexit - Issue IBPB only on VMEXIT
6715 (cloud-specific mitigation)
6740 on - Unconditionally disable Speculative Store Bypass
6741 off - Unconditionally enable Speculative Store Bypass
6742 auto - Kernel detects whether the CPU model contains an
6748 prctl - Control Speculative Store Bypass per thread
6752 seccomp - Same as "prctl" above, but all seccomp threads
6760 on,auto - On Power8 and Power9 insert a store-forwarding
6764 off - No action.
6778 off - not enabled
6780 warn - the kernel will emit rate-limited warnings
6788 fatal - the kernel will send SIGBUS to applications
6793 ratelimit:N -
6794 Set system wide rate limit to N bus locks
6813 Certain CPUs are vulnerable to an MDS-like
6833 This kernel-boot parameter defaults to 128,
6834 but takes effect only when the low-order four
6844 1: At init_srcu_struct() time.
6846 3: Decide at boot time (default).
6851 instead of the compile-time CONFIG_NR_CPUS.
6855 grace-period sequence counter wrap for the
6856 srcu_data structure's ->srcu_gp_seq_needed field.
6857 The greater the number of bits set in this kernel
6867 expediting. Set to zero to disable automatic
6871 Specifies the number of no-delay instances
6878 Specifies the per-grace-period phase, number of
6879 non-sleeping polls of readers. Beyond this limit,
6885 Specifies number of microseconds of non-sleeping
6886 delay between each non-sleeping poll of readers.
6889 Specifies the number of update-side contention
6894 set for contention-based conversions to occur.
6904 force-on: Unconditionally enable mitigation for
6906 force-off: Unconditionally disable mitigation for
6910 to allow userspace to register its
6923 consumed by the stack hash table. By default this is set
6929 stacktrace_filter=[function-list]
6931 will trace at boot up. function-list is a comma-separated
6933 time by the stack_trace_filter file in the debugfs
6939 Set the STI (builtin display/keyboard on the HP-PARISC
6941 as the initial boot-console.
6978 using these two parameters to set the minimum and
7001 to global on non-NUMA machines)
7008 server. Increasing these values may allow you to
7017 is set. Default value is 5.
7026 <int> -- Number of I/O TLB slabs
7027 <int> -- Second integer after comma. Number of swiotlb
7030 force -- force using of bounce buffers even if they
7032 noforce -- Never use bounce buffers (for debugging)
7037 Set a sysctl parameter, right before loading the init
7042 later by a loaded module cannot be set this way.
7047 Ignore sysrq setting - this boot parameter will
7052 Set the number of tcp_metrics_hash slots.
7055 cache size. See Documentation/networking/ip-sysctl.rst
7062 Specify "mem" (for Suspend-to-RAM) or "standby" (for
7067 wakeup-capable RTC alarm.
7070 Set number of hash buckets for TCP connection
7073 -1: disable all active trip points in all thermal zones
7077 -1: disable all critical trip points in all thermal zones
7084 -1: disable all passive trip points
7090 <deci-seconds>: poll all this frequency
7094 Format: <size>[KMG],<size>[KMG]:<state>;<size>[KMG]-<size>[KMG]:<state>
7099 See Documentation/admin-guide/mm/transhuge.rst for more
7107 Format: <size>[KMG],<size>[KMG]:<policy>;<size>[KMG]-<size>[KMG]:<policy>
7113 See Documentation/admin-guide/mm/transhuge.rst for more
7125 Prevent the CPU-hotplug component of torturing
7129 Dump the ftrace buffer at torture-test shutdown,
7133 with rotating-rust storage.
7138 disables verbose-printk() sleeping.
7141 Duration of each verbose-printk() sleep in jiffies.
7154 Specify that at suspend time, the tpm driver
7163 for the FIFO interface. By default it is set to false
7166 https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
7191 When tp_printk (above) is set, it can cause a lot of noise
7197 to console at the late_initcall_sync() time frame.
7200 [FTRACE] will set tracing buffer size on each cpu.
7202 trace_clock= [FTRACE] Set the clock used for tracing events
7204 local - Use the per CPU time stamp counter
7208 global - Event time stamps are synchronize across
7211 counter - Simple counting of events (1, 2, ..)
7215 uptime - Use jiffies as the time stamp.
7216 perf - Use the same clock that perf uses.
7217 mono - Use ktime_get_mono_fast_ns() for time stamps.
7218 mono_raw - Use ktime_get_raw_fast_ns() for time
7220 boot - Use ktime_get_boot_fast_ns() for time stamps.
7224 trace_event=[event-list]
7225 [FTRACE] Set and start specified trace events in order
7226 to facilitate early boot debugging. The event-list is a
7227 comma-separated list of trace events to enable. See
7238 trace_instance=[instance-info]
7244 Events can be enabled at the time the instance is created
7263 traceoff - Have the tracing instance tracing disabled after it is created.
7264 traceprintk - Have trace_printk() write into this trace instance
7286 memory may not be the same location each time, which will not preserve
7301 is set up to not wipe memory. For instance, CONFIG_RESET_ATTACK_MITIGATION
7311 trace_options=[option-list]
7313 The option-list is a comma delimited list of options
7327 trace_trigger=[trigger-list]
7329 Set a trigger on top of a specific event, with an optional
7365 This option can also be set at run time via the sysctl
7373 See Documentation/admin-guide/mm/transhuge.rst
7380 See Documentation/admin-guide/mm/transhuge.rst
7387 See Documentation/admin-guide/mm/transhuge.rst
7395 - "tpm"
7396 - "tee"
7397 - "caam"
7398 - "dcp"
7408 - "kernel"
7409 - the same value as trusted.source: "tpm" or "tee"
7410 - "default"
7431 high-resolution timer mode on older hardware, and in
7434 Used to run time disable IRQ_TIME_ACCOUNTING on any
7467 on - Enable TSX on the system. Although there are
7470 several previous speculation-related CVEs, and
7474 off - Disable TSX on the system. (Note that this
7482 auto - Disable TSX if X86_BUG_TAA is present,
7487 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7493 Similar to Micro-architectural Data Sampling (MDS)
7508 full - Enable TAA mitigation on vulnerable CPUs
7511 full,nosmt - Enable TAA mitigation and disable SMT on
7514 vulnerable to cross-thread TAA attacks.
7515 off - Unconditionally disable TAA mitigation
7517 On MDS-affected machines, tsx_async_abort=off can be
7529 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7535 See also Documentation/input/devices/joystick-parport.rst
7537 udbg-immortal [PPC] When debugging early kernel crashes that
7543 Set number of hash buckets for UDP/UDP-Lite connections
7545 uhci-hcd.ignore_oc=
7547 Some badly-designed motherboards generate lots of
7549 anything. Set this parameter to avoid log spamming.
7556 Allow skipping scalar unaligned access speed tests. This
7564 Allow skipping vector unaligned access speed tests. This
7572 unwind_debug [X86-64,EARLY]
7580 (default -1 = authorized (same as 1),
7585 [USB] The autosuspend time delay (in seconds) used
7586 for newly-detected USB devices (default 2). This
7587 is the time required before an idle device will be
7588 autosuspended. Devices for which the delay is set
7592 [USB] Set to log all usbfs traffic (default 0 = off).
7599 [USB] Set to cycle leds on hubs (default 0 = off).
7614 [USB] Specifies timeout for the initial 64-byte
7621 [USB] A list of quirk entries to augment the built-in
7624 VendorID:ProductID:Flags. The IDs are 4-digit hex
7625 numbers and Flags is a set of letters. Each letter
7626 will change the built-in quirk; setting it if it is
7627 clear and clearing it if it is set. The letters have
7631 a 255-byte read);
7635 Set-Interface requests);
7654 (bInterval-1).
7692 usb-storage.delay_use=
7699 usb-storage.quirks=
7701 override the built-in unusual_devs list. List
7704 and Product ID values (4-digit hex numbers) and
7705 Flags is a set of characters, each corresponding
7706 to a common usb-storage quirk flag as follows:
7720 240 sectors at a time, uas only);
7732 than 64 sectors = 32 KB at a time,
7744 t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
7748 medium is write-protected).
7757 1 - undefined instruction events
7758 2 - system calls
7759 4 - invalid data aborts
7760 8 - SIGSEGV faults
7761 16 - SIGBUS faults
7770 vdso32= [X86] Control the 32-bit vDSO
7771 vdso32=1: enable 32-bit VDSO
7772 vdso32=0 or vdso32=2: disable 32-bit VDSO
7775 details. If CONFIG_COMPAT_VDSO is set, the default is
7782 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
7789 If set to 1, on receiving an ACPI notify event
7792 the allocated input device. If set to 0, video driver
7813 vga= [BOOT,X86-32] Select a particular video mode
7815 Documentation/admin-guide/svga.rst.
7824 interface is meant to allow for selectively
7829 P Enable page structure init time poisoning
7830 - Disable all of the above options
7854 vsyscall= [X86-64,EARLY]
7857 code). Most statically-linked binaries and older
7881 see vga-softcursor.rst. Default: 2 = underline.
7886 This is a 16-member array composed of values
7887 ranging from 0-255.
7892 This is a 16-member array composed of values
7893 ranging from 0-255.
7898 This is a 16-member array composed of values
7899 ranging from 0-255.
7904 Set system-wide default UTF-8 mode for all tty's.
7905 Default is 1, i.e. UTF-8 mode is enabled for all
7910 Format=<-1|0|1>
7911 Set system-wide default for whether a cursor
7912 is shown on new VTs. Default is -1,
7917 vt.italic= [VT] Default color for italic text; 0-15.
7920 vt.underline= [VT] Default color for underlined text; 0-15.
7924 see Documentation/watchdog/watchdog-parameters.rst
7925 or other driver-specific files in the
7930 Set the hard lockup detector stall duration
7932 threshold is set to twice the value. A value of 0
7939 Format: <cpu-list>
7960 Per-cpu work items which run for longer than this
7963 them from noticeably delaying other per-cpu work
7966 If CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel
7972 If CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel
7981 Per-cpu workqueues are generally preferred because
7983 locality; unfortunately, per-cpu workqueues tend to
7986 Enabling this makes the per-cpu workqueues which
8000 Documentation/core-api/workqueue.rst.
8013 forces round-robin CPU selection to flush out
8021 on - Enable writecombine, use WUC for ioremap_wc()
8022 off - Disable writecombine, use SUC for ioremap_wc()
8024 x2apic_phys [X86-64,APIC,EARLY] Use x2apic physical mode instead of
8028 xen_512gb_limit [KNL,X86-64,XEN]
8038 ide-disks -- unplug primary master IDE devices
8039 aux-ide-disks -- unplug non-primary-master IDE devices
8040 nics -- unplug network devices
8041 all -- unplug all emulated devices (NICs and IDE disks)
8042 unnecessary -- unplugging emulated devices is
8045 never -- do not unplug even if version check succeeds
8059 Select whether to always use non-faulting (safe) MSR
8079 xen_timer_slop= [X86-64,XEN,EARLY]
8080 Set the timer slop (in nanoseconds) for the virtual Xen
8087 The time (in seconds) to wait before giving up to boot
8098 After which time (jiffies) the event handling loop
8104 preferred over the 2-level event handling, as it is
8121 xive.store-eoi=off [PPC]
8127 xhci-hcd.quirks [USB,KNL]