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 nospcr -- disable console in ACPI SPCR table as
41 If set to vendor, prefer vendor-specific driver
44 If set to video, use the ACPI video.ko driver.
45 If set to native, use the device's native backlight mode.
46 If set to none, disable the ACPI backlight interface.
73 Documentation/firmware-guide/acpi/debug.rst for more information about
131 Format: <byte> or <bitmap-list>
134 Disable auto-serialization of AML methods
137 auto-serialization feature.
145 Disable installation of static SSDTs at early boot time
155 Ignore the ACPI-based watchdog interface (WDAT) and let
176 acpi_osi=! # disable all built-in OS vendor
178 acpi_osi=!! # enable all built-in OS vendor
240 For broken nForce2 BIOS resulting in XT-PIC timer.
249 as soon as the kernel's real-mode entry point is called.
255 on docking. So the default behaviour is to allow resume
266 sci_force_enable causes the kernel to set SCI_EN directly
287 See Documentation/sound/alsa-configuration.rst
290 Allow the default userspace alignment fault handler
294 align_va_addr= [X86-64]
296 allocating a VMA at process creation time. This option
299 CPU-intensive style benchmark, and it can vary highly in
302 32: only for 32-bit processes
303 64: only for 64-bit processes
304 on: enable for both 32- and 64-bit processes
305 off: disable for both 32- and 64-bit processes
315 Allow execve() of 32-bit applications and setting of the
317 subset of the CPUs support 32-bit EL0. When this
318 parameter is present, the set of CPUs supporting 32-bit
320 and hot-unplug operations may be restricted.
322 See Documentation/arch/arm64/asymmetric-32bit.rst for more
325 amd_iommu= [HW,X86-64]
328 fullflush - Deprecated, equivalent to iommu.strict=1
329 off - do not initialize any AMD IOMMU found in
331 force_isolation - Force device isolation for all
336 force_enable - Force enable the IOMMU on platforms known
339 pgtbl_v1 - Use v1 page table for DMA-API (Default).
340 pgtbl_v2 - Use v2 page table for DMA-API.
341 irtcachedis - Disable Interrupt Remapping Table (IRT) caching.
342 nohugepages - Limit page-sizes used for v1 page-tables
344 v2_pgsizes_only - Limit page-sizes used for v1 page-tables
348 amd_iommu_dump= [HW,X86-64]
354 amd_iommu_intr= [HW,X86-64]
357 legacy - Use legacy interrupt remapping mode.
358 vapic - Use virtual APIC mode, which allows IOMMU
360 This mode requires kvm-amd.avic=1.
389 Disable amd-pstate preferred core.
402 Power management functions (SPARCstation-4/5 + deriv.)
404 Disable APC CPU standby support. SPARCstation-Fox does
405 not play well with APC CPU idle - disable it if you have
412 when initialising the APIC and IO-APIC components.
413 For X86-32, this can also be used to specify an APIC
433 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
436 0 -- disable.
437 1 -- enable.
438 Default value is set via kernel config option.
440 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
450 Set instructions support
473 atkbd.set= [HW] Select keyboard code set
485 audit= [KNL] Enable the audit sub-system
487 0 | off - kernel audit is disabled and can not be
489 unset - kernel audit is initialized but disabled and
491 1 | on - kernel audit is initialized and partially
497 audit_backlog_limit= [KNL] Set the audit queue size limit.
504 0 - Disable the BAU.
505 1 - Enable the BAU.
506 unset - Disable the BAU.
528 for writing, i.e., allow / disallow writes that bypass
545 See Documentation/block/cmdline-partition.rst
559 See Documentation/admin-guide/bootconfig.rst
564 bttv.pll= See Documentation/admin-guide/media/bttv.rst
569 at a time.
573 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
581 [NET] Specifies amount of time (in seconds) that
592 inclusive. See arch/mips/include/asm/pgtable-bits.h
602 - foo isn't auto-mounted if you mount all cgroups in
604 - foo isn't visible as an individually mountable
606 - if foo is an optional feature then the feature is
612 Specifying "pressure" disables per-cgroup pressure
630 nosocket -- Disable socket memory accounting.
631 nokmem -- Disable kernel memory accounting.
632 nobpf -- Disable BPF memory accounting.
634 checkreqprot= [SELINUX] Set initial checkreqprot flag value.
637 0 -- check protection applied by kernel (includes
639 1 -- check protection requested by application.
640 Default value is set via a kernel config option.
651 numbers X. Note the Linux-specific bits are not necessarily
652 stable over kernel options, but the vendor-specific
672 force such clocks to be always-on nor does it reserve
676 information, see Documentation/driver-api/clk.rst.
678 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
695 [X86-32] pit,hpet,tsc;
702 [X86-64] hpet,tsc
708 architected timer so that code using WFE-based polling
722 clocksource-wdtest.holdoff= [KNL]
723 Set the time in seconds that the clocksource
728 cma=nn[MG]@[start[MG][-end[MG]]]
739 Sets the size of kernel per-numa memory area for
741 per-numa CMA altogether. And If this option is not
743 With per-numa CMA enabled, DMA users on node nid will
768 allocations, by default set to 256K.
770 com20020= [HW,NET] ARCnet - COM20020 chipset
774 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
778 ARCnet - COM90xx chipset (memory-mapped buffers)
786 When set to true, drop data on the 3215 console when
791 This leads to a much faster boot time when a 3270
807 See Documentation/admin-guide/serial-console.rst for more
822 $ ls -d /sys/bus/serial-base/devices/*:*.*/tty/*
823 /sys/bus/serial-base/devices/00:04:0.0/tty/ttyS0
836 Start an early, polled-mode console on the 8250/16550
839 MMIO inter-register address stride is either 8-bit
840 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
844 the h/w is not re-initialized.
864 "[time stamp] text\n" format (time stamp may not be
868 Switch to syslog format: "<%u>[time stamp] text\n"
871 syscall, or to executing "dmesg -S --raw" or to reading
888 1: enable debugging at boot time
895 disable the cpuidle sub-system
901 disable the cpufreq sub-system
909 [X86,EARLY] Delay for N microsec between assert and de-assert
921 Run kdump after running panic-notifiers and dumping
934 [KNL, X86-64, ARM64, RISCV, LoongArch] Select a region
937 See Documentation/admin-guide/kdump/kdump.rst for further details.
942 start-[end] where start and end are both
944 Documentation/admin-guide/kdump/kdump.rst for an example.
947 [KNL, X86-64, ARM64, RISCV, LoongArch] range could be
949 Allow kernel to allocate physical memory region from top,
955 [KNL, X86-64, ARM64, RISCV, LoongArch] range under 4G.
961 for 32-bit devices won't run out. Kernel would try to allocate
964 --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
965 --> arm64: 128MiB
966 --> riscv: 128MiB
967 --> loongarch: 128MiB
975 [KNL] Disable crypto self-tests
983 csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
998 See also Documentation/input/devices/joystick-parport.rst
1011 [KNL] verbose locking self-tests
1014 self-tests.
1016 (no extra messages), setting it to -1 (all bits set)
1017 will print _a_lot_ more information - normally only
1023 [KNL,EARLY] When CONFIG_DEBUG_PAGEALLOC is set, this
1042 [KNL,EARLY] When CONFIG_DEBUG_PAGEALLOC is set, this parameter
1043 enables the feature at boot time. By default, it is
1052 Format: { on, no-mount, off }
1054 no-mount:
1059 get a -EPERM as result when trying to register files
1063 Default value is set in build-time with a kernel configuration.
1075 Documentation/admin-guide/mm/hugetlbpage.rst.
1079 [KNL] Debugging option to set a timeout in seconds for
1083 of 0 will timeout at the end of initcalls. If the time
1089 delayacct [KNL] Enable per-task delay accounting
1106 [HW] Allow controlling fans only if SYS_ADMIN
1107 capability is set.
1128 Set number of hash buckets for dentry cache.
1175 entries for DMA-API debugging code. One entry is
1176 required per DMA-API allocation. Use this if the
1177 DMA-API debugging code disables itself because the
1181 With this option the DMA-API debugging driver
1182 filter feature can be enabled at boot time. Just
1190 vulnerability which may allow userspace to infer
1198 This parameter overrides the compile time default set
1205 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
1219 An EDID data set will only be used for a particular
1222 data set by separating the files with a comma. An EDID
1223 data set with no connector name will be used for
1230 Control how the dt_cpu_ftrs device-tree binding is
1240 what data is available or for reverse-engineering.
1244 Enable debug messages at boot time. See
1245 Documentation/admin-guide/dynamic-debug-howto.rst
1256 determined by stdout-path property in device tree's
1261 Start an early, polled-mode console on a Cadence
1272 Start an early, polled-mode console on the 8250/16550
1274 MMIO inter-register address stride is either 8-bit
1275 (mmio) or 32-bit (mmio32 or mmio32be).
1280 the uart clock frequency; if unspecified, it is set
1285 Start an early, polled-mode console on a pl011 serial
1289 the driver will use only 32-bit accessors to read/write
1298 Start an early, polled-mode console on a meson serial
1304 Start an early, polled-mode console on an msm serial
1310 Start an early, polled-mode console on an msm serial
1316 Start an early, polled-mode console on a serial port
1322 Start an early, polled-mode console on a serial port
1328 Use RISC-V SBI (Supervisor Binary Interface) for early
1346 Start an early, polled-mode console on a lantiq serial
1360 Start an early, polled-mode, output-only console on the
1365 Start an early, polled-mode console on the
1371 Start an early, polled-mode console on a Qualcomm
1379 coherent non-x86 systems that use system memory for
1409 be used at a time.
1465 no_disable_early_pci_dma: Leave the busmaster bit set
1478 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1484 ekgdboc= [X86,KGDB,EARLY] Allow early kernel console debugging
1495 elanfreq= [X86-32]
1503 See Documentation/admin-guide/kdump/kdump.rst for details.
1514 The kernel tries to set a reasonable default.
1516 enforcing= [SELINUX] Set initial enforcing status.
1519 0 -- permissive (log only, no denials).
1520 1 -- enforcing (deny and log).
1552 See also Documentation/fault-injection/.
1556 See Documentation/admin-guide/sysctl/net.rst for
1560 See Documentation/admin-guide/blockdev/floppy.rst.
1562 forcepae [X86-32]
1569 fred= [X86-64]
1576 [FTRACE] will set and start the specified tracer
1620 ftrace_filter=[function-list]
1622 tracer at boot up. function-list is a comma-separated
1624 time by the set_ftrace_filter file in the debugfs
1627 ftrace_notrace=[function-list]
1629 function-list. This list can be changed at run time
1633 ftrace_graph_filter=[function-list]
1636 function-list is a comma-separated list of functions
1637 that can be changed at run time by the
1640 ftrace_graph_notrace=[function-list]
1642 function-list. This list is a comma-separated list of
1643 functions that can be changed at run time by the
1649 can be changed at run time by the max_graph_depth file
1662 off -- Don't create device links from firmware info.
1663 permissive -- Create device links from firmware info
1666 on -- Create device links from firmware info and use it
1668 rpm -- Like "on", but also use to order runtime PM.
1681 strict -- Default. Continue waiting on consumers to
1683 timeout -- Give up waiting on consumers and call
1693 See also Documentation/input/devices/joystick-parport.rst
1697 gart_fix_e820= [X86-64,EARLY] disable the fix e820 for K8 GART
1721 gcov_persist= [GCOV] When non-zero (default), profiling data for
1725 debugfs files are removed at module unload time.
1731 gpio-mockup.gpio_mockup_ranges
1734 gpio-mockup.gpio_mockup_named_lines
1766 against bounds-checking flaws in the kernel's
1772 [KNL] Should the hard-lockup detector generate
1778 for 64-bit NUMA, off otherwise.
1786 corresponding firmware-first mode error processing
1795 (that will set all pages holding image data
1796 during restoration read-only).
1820 hostname= [KNL,EARLY] Set the hostname (aka UTS nodename).
1824 Using this parameter to set the hostname makes it
1825 possible to ensure the hostname is correctly set before
1828 has been explicitly set, resulting in the calling
1833 hpet= [X86-32,HPET] option to control HPET usage
1837 force: allow force enabled of undocumented chips (ICH4,
1841 hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET
1842 registers. Default set by CONFIG_HPET_MMAP_DEFAULT.
1850 number of pages to allocate per-node can be specified.
1851 See also Documentation/admin-guide/mm/hugetlbpage.rst.
1862 Documentation/admin-guide/mm/hugetlbpage.rst.
1873 boot-time allocation of gigantic hugepages is skipped.
1901 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1907 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1913 which allow the hypervisor to 'idle' the guest
1923 Set device-properties for ACPI-enumerated I2C-attached
1924 touchscreen, to e.g. fix coordinates of upside-down
1932 Omit "=<val>" entirely Set a boolean device-property
1933 Unsigned number Set a u32 device-property
1934 Anything else Set a string device-property
1937 i2c_touchscreen_props=GDIX1001:touchscreen-inverted-x:
1938 touchscreen-inverted-y
1940 i2c_touchscreen_props=MSSL1680:touchscreen-size-x=1920:
1941 touchscreen-size-y=1080:touchscreen-inverted-y:
1942 firmware-name=gsl1680-vendor-model.fw:silead,home-button
1947 (disabled by default, and as a pre-condition
1949 i8042.direct [HW] Put keyboard port into non-translated mode
1963 suspend-to-ram transitions, only during s2r
1973 [HW] Allow deferred probing upon i8042 probe errors
1979 set the brightness of the panel backlight. Normally a
1982 to maximum brightness. If this parameter is set to 0
1984 is set to 1, a brightness value of 0 sets the backlight
1987 -1 -- never invert brightness
1988 0 -- machine default
1989 1 -- force brightness inversion
1991 ia32_emulation= [X86-64]
1993 When true, allows loading 32-bit programs and executing 32-bit
1995 boot time. When false, unconditionally disables IA32 emulation.
2009 idle=nomwait: Disable mwait for CPU C-states
2013 Allow force disabling of Shared Virtual Memory (SVA)
2014 support for the idxd driver. By default it is set to
2019 Allow override of default traffic class configuration
2020 for the device. By default it is set to false (0).
2029 of an ELF file header flag individually set by each
2037 legacy only accept legacy-NaN binaries, if supported
2039 2008 only accept 2008-NaN binaries, if supported
2050 'relaxed' straps the emulator for both legacy-NaN and
2051 2008-NaN, whereas 'strict' enables legacy-NaN only on
2060 Ignore loglevel setting - this will print /all/
2072 Set number of hash buckets for inode cache.
2101 mode bit set by either the effective uid (euid=0) or
2127 Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
2128 "ima-sigv2" }
2129 Default: "ima-ng"
2137 Set the minimal file size for using asynchronous hash.
2146 Set hashing buffer size. Default: 4k.
2161 initcall_blacklist= [KNL] Do not execute a comma-separated list of
2162 initcall functions. Useful for debugging built-in
2189 Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON.
2193 Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON.
2207 0 -- basic integrity auditing messages. (Default)
2208 1 -- additional integrity auditing messages.
2236 could harm performance of some high-throughput
2245 1 to 9 specify maximum depth of C-state.
2254 algorithms for p-state selection. There are two
2255 P-state selection algorithms provided by
2258 on whether or not the hardware managed P-states
2265 used along with the hardware-managed P-states (HWP)
2269 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2270 instead of acpi-cpufreq may disable platform features, such
2272 P-States information being indicated to OSPM and therefore
2275 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2288 Allow per-logical-CPU P-State performance control limits using
2291 intremap= [X86-64,Intel-IOMMU,EARLY]
2296 BIOS x2APIC opt-out request will be ignored
2322 0 - Try to allocate a 32-bit DMA address first, before
2324 1 - Allocate directly from the full usable range,
2326 greater than 32-bit addressing.
2330 0 - Lazy mode.
2336 1 - Strict mode.
2339 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2341 legacy driver-specific options takes precedence.
2346 0 - Use IOMMU translation for DMA.
2347 1 - Bypass the IOMMU for DMA.
2348 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2350 io7= [HW] IO7 for Marvel-based Alpha systems
2365 See Documentation/admin-guide/nfs/nfsroot.rst.
2382 irqaffinity= [SMP] Set the default irq affinity mask
2401 Enables support for pseudo-NMIs in the kernel. This
2419 isolcpus= [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
2420 [Deprecated - use cpusets instead]
2421 Format: [flag-list,]<cpu-list>
2447 move in and out of an isolated set anytime.
2452 "number of CPUs in system - 1".
2478 The format of <cpu-list> is described above.
2482 ivrs_ioapic [HW,X86-64]
2483 Provide an override to the IOAPIC-ID<->DEVICE-ID
2487 For example, to map IOAPIC-ID decimal 10 to
2493 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2496 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2500 ivrs_hpet [HW,X86-64]
2501 Provide an override to the HPET-ID<->DEVICE-ID
2505 For example, to map HPET-ID decimal 10 to
2511 * To map HPET-ID decimal 0 to PCI device 00:14.0
2514 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2518 ivrs_acpihid [HW,X86-64]
2519 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2523 For example, to map UART-HID:UID AMD0020:0 to
2529 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2532 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2556 the kernel for non-movable allocations. The requested
2566 subsystem. Note that allocations like PTEs-from-HighMem
2574 for non-movable allocations and remaining memory is used
2585 gdb or control-c on the dbgp connection. When
2586 not using this parameter you use sysrq-g to break into
2591 or a supported polling keyboard driver (non-usb).
2618 Configure the RouterBoard 532 series on-chip
2621 kmemleak= [KNL,EARLY] Boot-time kmemleak enable/disable
2627 kprobe_event=[probe-list]
2628 [FTRACE] Add kprobe events and enable at boot time.
2629 The probe-list is a semicolon delimited list of probe
2647 CONFIG_KUNIT to be set to be fully enabled. The
2659 execution by eliminating the write-protection faults
2665 disabling eager page splitting to allow huge pages to
2686 virtualization on-demand when creating and destroying
2694 is that doing so may interfere with using out-of-tree
2720 [KVM] Controls the time period at which KVM zaps 4KiB pages
2721 back to huge pages. If the value is a non-zero N, KVM will
2726 kvm-amd.nested= [KVM,AMD] Control nested virtualization feature in
2729 kvm-amd.npt= [KVM,AMD] Control KVM's use of Nested Page Tables,
2730 a.k.a. Two-Dimensional Page Tables. Default is 1
2734 kvm-arm.mode=
2740 nvhe: Standard nVHE-based mode, without support for
2743 protected: nVHE-based mode with support for guests whose
2746 nested: VHE-based mode with support for nested
2755 kvm-arm.vgic_v3_group0_trap=
2756 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-0
2759 kvm-arm.vgic_v3_group1_trap=
2760 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-1
2763 kvm-arm.vgic_v3_common_trap=
2767 kvm-arm.vgic_v4_enable=
2768 [KVM,ARM,EARLY] Allow use of GICv4 for direct
2771 kvm-arm.wfe_trap_policy=
2772 [KVM,ARM] Control when to set WFE instruction trap for
2776 trap: set WFE instruction trap
2780 kvm-arm.wfi_trap_policy=
2781 [KVM,ARM] Control when to set WFI instruction trap for
2785 trap: set WFI instruction trap
2797 kvm-intel.ept= [KVM,Intel] Control KVM's use of Extended Page Tables,
2798 a.k.a. Two-Dimensional Page Tables. Default is 1
2802 kvm-intel.emulate_invalid_guest_state=
2804 state. Ignored if kvm-intel.enable_unrestricted_guest=1,
2810 kvm-intel.flexpriority=
2815 kvm-intel.nested=
2819 kvm-intel.unrestricted_guest=
2825 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2826 CVE-2018-3620.
2837 kvm-intel.vpid= [KVM,Intel] Control KVM's use of Virtual Processor
2857 on - enable the interface for the mitigation
2922 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2928 lapic [X86-32,APIC,EARLY] Enable the local APIC even if BIOS
2932 value for LAPIC timer one-shot implementation. Default
2952 when set.
2955 libata.force= [LIBATA] Force configurations. The format is a comma-
2967 first fan-out link behind PMP device. It does not
2981 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2988 * rstonce: only attempt one reset during hot-unplug
3005 * max_trim_128m: Set 128M maximum trim size limit.
3023 * max_sec_128: Set transfer size limit to 128 sectors.
3025 * max_sec_1024: Set or clear transfer size limit to
3028 * max_sec_lba48: Set or clear transfer size limit to
3062 Enable the kernel lockdown feature. If set to
3063 integrity, kernel features that allow userland to
3064 modify the running kernel are disabled. If set to
3065 confidentiality, kernel features that allow userland
3070 Set the time limit in jiffies for a lock
3083 Specify the number of self-propagating call_rcu()
3084 chains to set up. These are used to ensure that
3086 in progress at any given time. Defaults to 0,
3091 occasional long-duration lock hold time. Defaults
3102 Set the number of locking read-acquisition kthreads.
3103 Defaults to being automatically set based on the
3107 Set the number of locking write-acquisition kthreads.
3110 Set time (s) after boot for CPU-hotplug testing.
3113 Set time (s) between CPU-hotplug operations, or
3114 zero to disable CPU-hotplug testing.
3117 Do periodic testing of real-time lock priority
3122 non-real-time spinlocks, due to their disabling
3123 of preemption. Note that non-realtime mutexes
3130 number of boosts per unit time remains roughly
3136 Set task-shuffle interval (jiffies). Shuffling
3137 tasks allows some CPUs to go into dyntick-idle
3141 Set time (s) after boot system shutdown. This
3142 is useful for hands-off automated testing.
3145 Time (s) between statistics printk()s.
3148 Time (s) to stutter testing, for example,
3161 Run the write-side locktorture kthreads at
3162 sched_set_fifo() real-time priority.
3180 7 (KERN_DEBUG) debug-level messages
3192 logo.nologo [FB] Disables display of the built-in Linux logo.
3210 an IEEE 1284-compliant printer is attached; if
3216 time-consuming boot-time autodetection (up to 250 ms per
3236 Example: machtype=lemote-yeeloong-2f-7inch
3248 (loop.max_loop) unconditionally pre-created at init time. The default
3251 devices can be requested on-demand with the
3252 /dev/loop-control interface.
3254 mce [X86-32] Machine Check Exception
3256 mce=option [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
3259 See Documentation/admin-guide/md.rst.
3266 Control mitigation for the Micro-architectural Data
3281 full - Enable MDS mitigation on vulnerable CPUs
3282 full,nosmt - Enable MDS mitigation and disable
3284 off - Unconditionally disable MDS mitigation
3286 On TAA-affected machines, mds=off can be prevented by
3295 For details see: Documentation/admin-guide/hw-vuln/mds.rst
3297 mem=nn[KMG] [HEXAGON,EARLY] Set the memory size.
3310 [ARC,MICROBLAZE] - the limit applies only to low memory,
3313 [ARM64] - only limits memory covered by the linear
3321 Note that this only takes effects during boot time since
3326 [ARM,MIPS,EARLY] - override the memory layout
3333 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
3339 [KNL,SH] Allow user to override the default size for
3340 per-device physically contiguous DMA buffers.
3343 [KNL] Set the initial state for the memory hotplug
3345 set according to the
3348 See Documentation/admin-guide/mm/memory-hotplug.rst.
3373 Example: Exclude memory from 0x18690000-0x1869ffff
3387 memmap=<size>%<offset>-<oldtype>+<newtype>
3389 from <oldtype> to <newtype>. If "-<oldtype>" is left
3404 repeatable BIOS-originated corruption always
3426 hotadded memory which will allow to hotadd a
3443 pattern from a given set of patterns. Memtest
3448 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
3454 Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
3458 s2idle - Suspend-To-Idle
3459 shallow - Power-On Suspend or equivalent (if supported)
3460 deep - Suspend-To-RAM or equivalent (if supported)
3461 See Documentation/admin-guide/pm/sleep-states.rst.
3463 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
3479 0 - The attached screen is the 3.5" TFT
3480 1 - The attached screen is the 7" TFT
3481 2 - The VGA Shield is attached (1024x768)
3485 b - Enable backlight. The TFT backlight pin will be
3489 c - Enable the s3c camera interface.
3490 t - Reserved for enabling touchscreen support. The
3494 https://repo.or.cz/w/linux-2.6/mini2440.git
3498 CPU vulnerabilities. This is a set of curated,
3499 arch-independent options, each of which is an
3500 aggregation of existing arch-specific options.
3529 ssbd=force-off [ARM64]
3542 have other ways of avoiding SMT-based attacks.
3556 [KNL,EARLY] When CONFIG_DEBUG_MEMORY_INIT is set, this
3577 full - Enable mitigation on vulnerable CPUs
3579 full,nosmt - Enable mitigation and disable SMT on
3582 off - Unconditionally disable mitigation
3595 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3605 [KNL] When set to true, modules will use async probing
3614 [KNL] When CONFIG_MODULE_DEBUG_AUTOLOAD_DUPS is set,
3617 if MODULE_DEBUG_AUTOLOAD_DUPS_TRACE is set, WARN_ON()s
3620 [KNL] When CONFIG_MODULE_SIG is set, this means that
3622 Note that if CONFIG_MODULE_SIG_FORCE is set, that
3625 module_blacklist= [KNL] Do not load a comma-separated list of
3629 [MOUSE] Maximum time between finger touching and
3650 movable_node [KNL,EARLY] Boot-time switch to make hotplugable memory
3657 Format: <name>,<region-number>,<size>,<offset>
3660 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3671 registers at boot time.
3688 Set to 2 or more if your graphical card needs more.
3692 at a time.
3699 something different and driver-specific.
3704 [NET] Specifies amount of time (in seconds) that
3723 [NFSv4] set the total number of threads that the
3728 [NFS] set the TCP port on which the NFSv4 callback
3739 [NFS] enable 64-bit inode numbers.
3740 If zero, the NFS client will fake up a 32-bit inode
3742 of returning the full 64-bit number.
3743 The default is to return 64-bit inode numbers.
3746 [NFS] set the maximum lifetime for idmapper cache
3765 [NFSv4] When set to the default of '1', this option
3775 To turn off this behaviour, set the value to '0'.
3778 [NFS4] Specify an additional fixed unique ident-
3781 UUID that is generated at system install time.
3790 attempting to recover these locks, then set this
3808 whatever value is the default set by the layout
3809 driver. A non-zero value sets the minimum interval
3813 [NFSv4.2] When set to 1, the server will support
3814 server-to-server copies for which this server is
3818 [NFSv4] When set to the default of '1', the NFSv4
3826 server-to-server copy, knfsd temporarily mounts
3833 See Documentation/admin-guide/nfs/nfsroot.rst.
3835 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3836 See Documentation/admin-guide/nfs/nfsroot.rst.
3839 See Documentation/admin-guide/nfs/nfsroot.rst.
3843 NMI stack-backtrace request.
3852 0 - turn hardlockup detector in nmi_watchdog off
3853 1 - turn hardlockup detector in nmi_watchdog on
3854 rNNN - configure the watchdog with raw perf event 0xNNN
3858 watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set)
3867 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3871 no4lvl [RISCV,EARLY] Disable 4-level and 5-level paging modes.
3872 Forces kernel to use 3-level paging instead.
3874 no5lvl [X86-64,RISCV,EARLY] Disable 5-level paging mode. Forces
3875 kernel to use 4-level paging instead.
3904 nodsp [SH] Disable hardware DSP at boot time.
3908 no_entry_flush [PPC,EARLY] Don't flush the L1-D cache when entering the kernel.
3910 noexec32 [X86-64]
3911 This affects only 32-bit executables.
3912 noexec32=on: enable non-executable mappings (default)
3914 noexec32=off: disable non-executable mappings
3921 nofpu [MIPS,SH] Disable hardware FPU at boot time.
3925 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3927 legacy floating-point registers on task switch.
3938 compared. However, if this command-line option is
3965 In kernels built with CONFIG_NO_HZ_FULL=y, set
3979 nointremap [X86-64,Intel-IOMMU,EARLY] Do not enable interrupt
3981 [Deprecated - use intremap=off]
3987 noirqdebug [X86-32] Disables the code which attempts to detect and
3993 When CONFIG_RANDOMIZE_BASE is set, this disables
3997 no-kvmapf [X86,KVM,EARLY] Disable paravirtualized asynchronous page
4000 no-kvmclock [X86,KVM,EARLY] Disable paravirtualized KVM clock driver
4002 nolapic [X86-32,APIC,EARLY] Do not enable or use the local APIC.
4004 nolapic_timer [X86-32,APIC,EARLY] Do not use the local APIC timer.
4006 nomce [X86-32] Disable Machine Check Exception
4008 nomfgpt [X86-32] Disable Multi-Function General Purpose
4014 not load if they could possibly displace the pre-
4017 perform display-mode changes or accelerated rendering.
4030 nopcid [X86-64,EARLY] Disable the PCID cpu feature.
4035 nopti [X86-64,EARLY]
4045 which allow the hypervisor to 'idle' the guest on lock
4051 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
4057 no-scroll [VGA] Disables scrollback.
4058 This is required for the Braillex ib80-piezo Braille
4061 nosgx [X86-64,SGX,EARLY] Disables Intel SGX kernel support.
4081 nosoftlockup [KNL] Disable the soft-lockup detector.
4087 nospectre_bhb [ARM64,EARLY] Disable all mitigations for Spectre-BHB (branch
4088 history injection) vulnerability. System may allow data leaks
4097 prediction) vulnerability. System may allow data
4100 no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,LOONGARCH,EARLY]
4101 Disable paravirtualized steal time accounting. steal time
4110 [PPC,EARLY] Don't flush the L1-D cache after accessing user data.
4121 is set.
4123 no-vmw-sched-clock
4128 soft-lockup and NMI watchdog (hard-lockup).
4132 nox2apic [X86-64,APIC,EARLY] Do not enable x2APIC mode.
4135 LEGACY_XAPIC_DISABLED bit set in the
4140 enabling legacy floating-point and sse state.
4162 n. So during boot up some boot time memory for per-cpu
4163 variables need be pre-allocated for later physical cpu
4169 Disable NUMA, Only set up a single NUMA node
4193 This can be set from sysctl after boot.
4194 See Documentation/admin-guide/sysctl/vm.rst for details.
4197 See Documentation/core-api/debugging-via-ohci1394.rst for more
4204 waiting for the ACK, so if this is set too high
4212 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
4216 boundary - index of last SLC block on Flex-OneNAND.
4218 lock - Configure if Flex-OneNAND boundary should be locked.
4237 page_owner= [KNL,EARLY] Boot-time page_owner enabling option.
4243 page_poison= [KNL,EARLY] Boot-time parameter changing the state of
4264 Hexadecimal bitmask representing the set of TAINT flags
4266 called with any of the flags in this set.
4270 bitmask set on panic_on_taint.
4271 See Documentation/admin-guide/tainted-kernels.rst for
4324 Set to non-zero to probe primary and secondary ISA
4330 Set to non-zero if a chip is present that snoops speed
4335 Set to 1, 2, or 3 for HT 6560A on the primary channel,
4341 Set to 1, 2, or 3 for HT 6560B on the primary channel,
4347 IORDY enable mask. Set individual bits to allow IORDY
4359 Set to 1, 2, or 3 for Opti 82c611A on the primary
4365 Set to 1, 2, or 3 for Opti 82c465MV on the primary
4371 PIO mode mask for autospeed devices. Set individual
4372 bits to allow the use of the respective PIO modes.
4378 Set to non-zero to probe tertiary and further ISA
4394 Set to non-zero to probe QDI controllers. By default
4395 set to 1 if CONFIG_PATA_QDI_MODULE, 0 otherwise.
4399 Set to non-zero to probe Winbond controllers. Use
4402 By default set to 1 if CONFIG_PATA_WINBOND_VLB_MODULE,
4407 Supported PIO mode mask. Set individual bits to allow
4422 or a set of devices (<pci_dev>). These are
4446 bios [X86-32] force use of PCI BIOS, don't access
4448 has a non-standard PCI host bridge.
4449 nobios [X86-32] disallow use of PCI BIOS, only direct
4455 data in IO port 0xCFC, both 32-bit).
4457 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
4458 the function, IO port 0xCFA, also 8-bit, sets
4460 through ports 0xC000-0xCFFF).
4467 root domains (aka PCI segments, in ACPI-speak).
4475 disable the use of MSI interrupts system-wide.
4480 primary IO-APIC for bridges that cannot disable
4487 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
4504 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
4511 F0000h-100000h range.
4516 assign-busses [X86] Always assign all PCI bus
4537 <linux-pci@vger.kernel.org>.
4541 a bug to <linux-pci@vger.kernel.org>.
4553 bfsort Sort PCI devices into breadth-first order.
4556 nobfsort Don't sort PCI devices into breadth-first order.
4558 tuning and use the BIOS-configured MPS defaults.
4559 pcie_bus_safe Set every device's MPS to the largest value
4561 pcie_bus_perf Set device MPS to the largest allowable MPS
4562 based on its parent bus. Also set MRRS (Max
4566 pcie_bus_peer2peer Set every device's MPS to 128B, which
4568 configuration allows peer-to-peer DMA between
4571 that hot-added devices will work.
4586 A PCI-PCI bridge can be specified if resource
4592 for 4096-byte alignment.
4594 end-to-end CRC checking). Only effective if
4625 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4632 can resize a BAR to allow access to all VRAM.
4641 allow P2P traffic between devices through
4656 bit-0 : ACS Source Validation
4657 bit-1 : ACS Translation Blocking
4658 bit-2 : ACS P2P Request Redirect
4659 bit-3 : ACS P2P Completion Redirect
4660 bit-4 : ACS Upstream Forwarding
4661 bit-5 : ACS P2P Egress Control
4662 bit-6 : ACS Direct Translated P2P
4672 Validation unchanged from whatever power-up
4673 or firmware set it to.
4694 dpc-native Use native PCIe service for DPC only. May
4711 Keep all power-domains already enabled by bootloader on,
4717 boot time.
4729 pirq= [SMP,APIC] Manual mp-table setup
4730 See Documentation/arch/x86/i386/IO-APIC.rst.
4734 See also Documentation/admin-guide/parport.rst.
4744 cleared). If a number is given, then MMCR1 is set to
4753 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4762 { on | off | curr | res | no-curr | no-res }
4786 Set the number of possible CPUs, overriding the
4807 none - Limited to cond_resched() calls
4808 voluntary - Limited to cond_resched() and might_sleep() calls
4809 full - Any section that isn't explicitly preempt disabled
4814 print-fatal-signals=
4820 coredump - etc.
4823 you might want to try "ulimit -i unlimited".
4835 or lockdep-detected issues (only if lock debug is on).
4844 on - unlimited logging to /dev/kmsg from userspace
4845 off - logging to /dev/kmsg disabled
4846 ratelimit - ratelimit the logging
4849 printk.time= Show timing data prefixed to each printk message line
4855 overridden without restrictions. This option may be set to
4857 - 'always': traditional behavior always allows mem overrides.
4858 - 'ptrace': only allow mem overrides for active ptracers.
4859 - 'never': never allow mem overrides.
4863 Limit processor to maximum C-state
4867 Ignore the _CST method to determine C-states,
4874 Param: "schedule" - profile schedule points.
4875 Param: "kvm" - profile VM exits.
4876 Param: <number> - step/bucket size as a power of 2 for
4877 statistical time based profiling.
4894 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
4900 [HW,MOUSE] Set desired mouse resolution, in dpi.
4907 pti= [X86-64] Control Page Table Isolation of user and
4912 on - unconditionally enable
4913 off - unconditionally disable
4914 auto - kernel detects whether your CPU model is
4920 [KNL] Number of legacy pty's. Overwrites compiled-in
4932 See Documentation/admin-guide/md.rst.
4935 See Documentation/admin-guide/blockdev/ramdisk.rst.
4954 cross-syscall address exposures. This is only
4960 ras=option[,option,...] [KNL] RAS-specific options
4966 rcu_nocbs[=cpu-list]
4971 enable the no-callback CPU mode, which prevents
4976 "p" for RCU-preempt, "s" for RCU-sched, and "g"
4980 and real-time workloads. It can also improve
4984 list of CPUs is set to no-callback mode from boot.
4987 arguments are omitted, no CPU will be set to
4988 no-callback mode from boot but the mode may be
4999 This improves the real-time response for the
5006 Set maximum number of finished RCU callbacks to
5010 Do only a one-line RCU CPU stall warning when
5011 there is an ongoing too-long CSD-lock wait.
5017 If triggered before the RCU grace-period machinery
5026 Set the number of jiffies to delay each step of
5027 RCU grace-period cleanup.
5030 Set the number of jiffies to delay each step of
5031 RCU grace-period initialization.
5034 Set the number of jiffies to delay each step of
5035 RCU grace-period pre-initialization, that is,
5036 the propagation of recent CPU-hotplug changes up
5040 Set delay from grace-period initialization to
5046 Set delay between subsequent attempts to force
5051 Set required age in jiffies for a
5053 soliciting quiescent-state help from
5060 rcutree.jiffies_to_sched_qs. Any attempt to set
5065 Set the SCHED_FIFO priority of the RCU per-CPU
5068 and for the RCU grace-period kthreads (rcu_bh,
5070 set, valid values are 1-99 and the default is 1
5071 (the least-favored priority). Otherwise, when
5072 RCU_BOOST is not set, valid values are 0-99 and
5073 the default is zero (non-realtime operation).
5074 When RCU_NOCB_CPU is set, also adjust the
5078 On callback-offloaded (rcu_nocbs) CPUs,
5081 use of the ->nocb_bypass list. However, in the
5082 common non-flooded case, RCU queues directly to
5083 the main ->cblist in order to avoid the extra
5084 overhead of the ->nocb_bypass list and its lock.
5086 a single jiffy, RCU pre-queues the callbacks into
5087 the ->nocb_bypass queue. The definition of "too
5091 On callback-offloaded (rcu_nocbs) CPUs, avoid
5099 Set threshold of queued RCU callbacks beyond which
5103 Set threshold of queued RCU callbacks below which
5104 batch limiting is re-enabled.
5107 Set threshold of queued RCU callbacks beyond which
5108 RCU's force-quiescent-state scan will aggressively
5111 Set to less than zero to make this be set based
5112 on rcutree.qhimark at boot time and to zero to
5116 Set the page-cache refill delay (in milliseconds)
5117 in response to low-memory conditions. The range
5121 Set the shift-right count to use to compute
5122 the callback-invocation batch limit bl from
5127 order to allow the CPU to do other work.
5129 Please note that this callback-invocation batch
5130 limit applies only to non-offloaded callback
5139 cache-to-cache transfer latencies.
5145 and for NUMA systems with large remote-access
5158 Set the number of NOCB callback kthreads in
5161 the wakeup overhead on the global grace-period
5163 each group's NOCB grace-period kthread.
5166 Cause the grace-period kthread to get an extra
5168 it should at force-quiescent-state time.
5173 Limit the time spend invoking a batch of RCU
5181 this specifies an rcu_read_unlock()-time delay
5185 of RCU-protected pointers after the relevant
5194 If set to zero, move all RCU_SOFTIRQ processing to
5195 per-CPU rcuc kthreads. Defaults to a non-zero
5224 grace-period primitives such as call_rcu().
5230 corresponding flavor of rcu_barrier() to allow
5235 grace-period primitives.
5238 Set test-start holdoff period. The purpose of
5253 Set to measure performance of kfree_rcu() flooding.
5256 Test the double-argument variant of kfree_rcu().
5258 rcuscale.kfree_rcu_test_single, both the single-
5259 and double-argument variants are tested.
5262 Test the single-argument variant of kfree_rcu().
5264 rcuscale.kfree_rcu_test_double, both the single-
5265 and double-argument variants are tested.
5278 Set the minimum test run time in seconds. This
5279 does not affect the data-collection interval,
5284 Set number of RCU readers. The value -1 selects
5286 "n" less than -1 selects N-n+1, where N is again
5287 the number of CPUs. For example, -2 selects N
5288 (the number of CPUs), -3 selects N+1, and so on.
5289 A value of "n" less than or equal to -N selects
5293 Set number of RCU writers. The values operate
5302 complete. This is useful for hands-off automated
5309 Write-side holdoff between grace periods,
5314 Additional write-side holdoff between grace
5319 Set duration of force_quiescent_state bursts
5323 Set holdoff time within force_quiescent_state bursts
5327 Set wait time between force_quiescent_state bursts
5332 for RCU grace-period forward-progress testing
5339 Specify the fraction of a CPU-stall-warning
5340 period to do tight-loop forward-progress testing.
5344 forward-progress tests.
5348 need_resched() during tight-loop forward-progress
5352 Use conditional/asynchronous update-side
5356 Use expedited update-side primitives, if available.
5359 Use normal (non-expedited) asynchronous
5360 update-side primitives, if available.
5363 Use normal (non-expedited) synchronous
5364 update-side primitives, if available. If all
5368 they are all non-zero.
5376 Leak an RCU-protected pointer out of the reader.
5383 Set callbacks/threads for rcu_barrier() testing.
5386 Set number of concurrent RCU writers. These just
5391 Set number of RCU callback-offload togglers.
5395 Set the delay in milliseconds between successive
5396 callback-offload toggling attempts.
5399 Set number of RCU readers. The value -1 selects
5400 N-1, where N is the number of CPUs. A value
5401 "n" less than -1 selects N-n-2, where N is again
5402 the number of CPUs. For example, -2 selects N
5403 (the number of CPUs), -3 selects N+1, and so on.
5406 Enable debug-object double-call_rcu() testing.
5409 Set time (s) after boot for CPU-hotplug testing.
5412 Set time (jiffies) between CPU-hotplug operations,
5413 or zero to disable CPU-hotplug testing.
5416 Set the number of read-then-exit kthreads used
5418 task-exit processing.
5421 The number of times in a given read-then-exit
5422 episode that a set of read-then-exit kthreads
5427 read-then-exit testing episodes.
5430 Set task-shuffle interval (s). Shuffling tasks
5431 allows some CPUs to go into dyntick-idle mode
5435 Set time (s) after boot system shutdown. This
5436 is useful for hands-off automated testing.
5443 Sleep while stalling if set. This will result
5445 any other stall-related activity. Note that
5451 in scheduling-while-atomic splats.
5457 Time to wait (s) after boot before inducing stall.
5460 Disable interrupts while stalling if set, but only
5461 on the first stall in the set.
5470 grace-period kthread to test RCU CPU stall
5476 Time (s) between statistics printk()s.
5479 Time (s) to stutter testing, for example, specifying
5496 Test RCU's dyntick-idle handling. See also the
5521 during early boot, that is, during the time
5525 Set timeout for RCU CPU stall warning messages.
5530 Set timeout for expedited RCU CPU stall warning
5551 Use expedited grace-period primitives, for
5555 real-time latency, and degrade energy efficiency.
5559 Use only normal grace-period primitives,
5562 real-time latency, CPU utilization, and
5564 increased grace-period latency. This parameter
5571 only normal grace-period primitives. No effect
5577 post-boot attempt at an expedited RCU grace
5578 period to instead use normal non-expedited
5579 grace-period processing.
5582 Set the maximum number of callbacks present
5587 set to the default value of -1.
5590 Set the minimum number of callback-queuing-time
5591 lock-contention events per jiffy required to
5592 cause the RCU Tasks flavors to switch to per-CPU
5594 when rcupdate.rcu_task_enqueue_lim is set to
5595 the default value of -1.
5598 Set the number of callback queues to use for the
5600 of -1 allows this to be automatically (and
5605 Set time in jiffies during which RCU tasks will
5608 number avoids disturbing real-time workloads,
5613 cancel laziness on that CPU. Use -1 to disable
5619 Set initial timeout in jiffies for RCU task stall
5623 only printed prior to the stall-warning message
5630 Multiplier for time interval between successive
5641 Set timeout in jiffies for RCU task stall
5648 Set timeout in milliseconds RCU Tasks asynchronous
5655 Set timeout in milliseconds RCU Tasks
5671 force - Override the decision by the kernel to hide the
5691 (prefix with 'panic_' to set mode for panic
5699 Set test-start holdoff period. The purpose of
5711 Set the number of loops over the synchronization
5714 but the default has already reduced the per-pass
5719 Set number of readers. The default value of -1
5724 Set number of runs, each of which is dumped onto
5728 Set the read-side critical-section duration,
5732 Specify the read-protection implementation to test.
5757 [KNL, SMP] Set scheduler's default relax_domain_level.
5758 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
5788 reservetop= [X86-32,EARLY]
5805 See Documentation/power/swsusp-and-swap-files.rst
5821 AMD-based UNRET and IBPB mitigations alone do not stop
5823 sibling threads. For that reason, STIBP is used on pro-
5827 off - no mitigation
5828 auto - automatically select a migitation
5829 auto,nosmt - automatically select a mitigation,
5833 ibpb - On AMD, mitigate short speculation
5838 ibpb,nosmt - Like "ibpb" above but will disable SMT
5842 unret - Force enable untrained return thunks,
5843 only effective on AMD f15h-f17h based
5845 unret,nosmt - Like unret, but will disable SMT when STIBP
5850 time according to the CPU.
5877 ro [KNL] Mount root device read-only on boot
5880 on Mark read-only kernel memory as read-only (default).
5881 off Leave read-only kernel memory writable for debugging.
5882 full Mark read-only kernel memory and aliases as read-only
5889 debug-uart get routed to the D+ and D- pins of the usb
5895 block/early-lookup.c for details.
5903 rootflags= [KNL] Set root filesystem mount option string
5905 rootfstype= [KNL] Set root filesystem type
5911 rootwait= [KNL] Maximum time (in seconds) to wait for root device
5920 rw [KNL] Mount root device read-write on boot
5925 Set s390 IOTLB flushing mode
5956 [KNL, SMP] Set a decay shift for scheduler thermal
5974 to 10 seconds for built-in smp_call_function()
5981 that requesting even small non-zero numbers of
5988 The default of -1 specifies a number of kthreads
5993 test before initiating CPU-hotplug operations.
5997 CPU-hotplug operations. Specifying zero (which
5998 is the default) disables CPU-hotplug operations.
6004 Non-zero values are useful for automated tests.
6013 to the set of CPUs under test.
6027 "wait" parameter. A value of -1 selects the
6028 default if all other weights are -1. However,
6030 value of -1 will instead select a weight of zero.
6035 non-zero "wait" parameter. See weight_single.
6048 non-zero "wait" parameter. See weight_single
6060 non-zero "wait" parameter. See weight_single
6065 contention on all systems with CONFIG_MAXSMP set.
6067 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
6068 1 -- enable.
6076 selinux= [SELINUX] Disable or enable SELinux at boot time.
6079 0 -- disable.
6080 1 -- enable.
6083 serialnumber [BUGS=X86-32]
6085 sev=option[,option...] [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
6093 to set it to "all" by meaning -- no limit here.
6156 Specify the period of time in milliseconds
6161 of time. Defaults to 5,000 milliseconds, and
6164 using the csdlock_debug- kernel parameter.
6169 system. By default, let CSD-lock acquisition
6171 for this value provides a 5-minute timeout.
6173 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
6174 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
6175 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
6176 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
6177 smsc-ircc2.ircc_irq= [HW] IRQ line
6178 smsc-ircc2.ircc_dma= [HW] DMA channel
6179 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
6184 smt= [KNL,MIPS,S390,EARLY] Set the maximum number of threads
6189 Default: -1 (no limit)
6192 [KNL] Should the soft-lockup detector generate panics.
6195 A value of 1 instructs the soft-lockup detector
6196 to panic the machine when a soft-lockup occurs. It is
6199 respective build-time switch to that functionality.
6202 [KNL] Should the soft-lockup detector generate
6207 See Documentation/admin-guide/laptops/sonypi.rst
6214 on - (default) Enable the HW or SW mitigation as
6217 vmexit - On systems which don't have the HW mitigation
6220 protected from VM-originated BHI attacks, but
6222 off - Disable the mitigation.
6229 on - unconditionally enable, implies
6231 off - unconditionally disable, implies
6233 auto - kernel detects whether your CPU model is
6237 mitigation method at run time according to the
6250 retpoline - replace indirect branches
6251 retpoline,generic - Retpolines
6252 retpoline,lfence - LFENCE; indirect branch
6253 retpoline,amd - alias for retpoline,lfence
6254 eibrs - Enhanced/Auto IBRS
6255 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
6256 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
6257 ibrs - use IBRS to protect kernel
6267 on - Unconditionally enable mitigations. Is
6270 off - Unconditionally disable mitigations. Is
6273 prctl - Indirect branch speculation is enabled,
6279 - Like "prctl" above, but only STIBP is
6285 - Same as "prctl" above, but all seccomp
6290 - Like "seccomp" above, but only STIBP is
6295 auto - Kernel selects the mitigation depending on
6306 off - Disable mitigation
6307 microcode - Enable microcode mitigation only
6308 safe-ret - Enable sw-only safe RET mitigation (default)
6309 ibpb - Enable mitigation by issuing IBPB on
6311 ibpb-vmexit - Issue IBPB only on VMEXIT
6312 (cloud-specific mitigation)
6337 on - Unconditionally disable Speculative Store Bypass
6338 off - Unconditionally enable Speculative Store Bypass
6339 auto - Kernel detects whether the CPU model contains an
6345 prctl - Control Speculative Store Bypass per thread
6349 seccomp - Same as "prctl" above, but all seccomp threads
6357 on,auto - On Power8 and Power9 insert a store-forwarding
6361 off - No action.
6375 off - not enabled
6377 warn - the kernel will emit rate-limited warnings
6385 fatal - the kernel will send SIGBUS to applications
6390 ratelimit:N -
6391 Set system wide rate limit to N bus locks
6410 Certain CPUs are vulnerable to an MDS-like
6430 This kernel-boot parameter defaults to 128,
6431 but takes effect only when the low-order four
6441 1: At init_srcu_struct() time.
6443 3: Decide at boot time (default).
6448 instead of the compile-time CONFIG_NR_CPUS.
6452 grace-period sequence counter wrap for the
6453 srcu_data structure's ->srcu_gp_seq_needed field.
6454 The greater the number of bits set in this kernel
6464 expediting. Set to zero to disable automatic
6468 Specifies the number of no-delay instances
6475 Specifies the per-grace-period phase, number of
6476 non-sleeping polls of readers. Beyond this limit,
6482 Specifies number of microseconds of non-sleeping
6483 delay between each non-sleeping poll of readers.
6486 Specifies the number of update-side contention
6491 set for contention-based conversions to occur.
6501 force-on: Unconditionally enable mitigation for
6503 force-off: Unconditionally disable mitigation for
6507 to allow userspace to register its
6520 consumed by the stack hash table. By default this is set
6526 stacktrace_filter=[function-list]
6528 will trace at boot up. function-list is a comma-separated
6530 time by the stack_trace_filter file in the debugfs
6536 Set the STI (builtin display/keyboard on the HP-PARISC
6538 as the initial boot-console.
6575 using these two parameters to set the minimum and
6598 to global on non-NUMA machines)
6605 server. Increasing these values may allow you to
6614 is set. Default value is 5.
6623 <int> -- Number of I/O TLB slabs
6624 <int> -- Second integer after comma. Number of swiotlb
6627 force -- force using of bounce buffers even if they
6629 noforce -- Never use bounce buffers (for debugging)
6634 Set a sysctl parameter, right before loading the init
6639 later by a loaded module cannot be set this way.
6644 Ignore sysrq setting - this boot parameter will
6649 Set the number of tcp_metrics_hash slots.
6652 cache size. See Documentation/networking/ip-sysctl.rst
6659 Specify "mem" (for Suspend-to-RAM) or "standby" (for
6664 wakeup-capable RTC alarm.
6667 Set number of hash buckets for TCP connection
6670 -1: disable all active trip points in all thermal zones
6674 -1: disable all critical trip points in all thermal zones
6681 -1: disable all passive trip points
6687 <deci-seconds>: poll all this frequency
6691 Format: <size>[KMG],<size>[KMG]:<state>;<size>[KMG]-<size>[KMG]:<state>
6696 See Documentation/admin-guide/mm/transhuge.rst for more
6712 Prevent the CPU-hotplug component of torturing
6716 Dump the ftrace buffer at torture-test shutdown,
6720 with rotating-rust storage.
6725 disables verbose-printk() sleeping.
6728 Duration of each verbose-printk() sleep in jiffies.
6741 Specify that at suspend time, the tpm driver
6750 for the FIFO interface. By default it is set to false
6753 https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
6778 When tp_printk (above) is set, it can cause a lot of noise
6784 to console at the late_initcall_sync() time frame.
6787 [FTRACE] will set tracing buffer size on each cpu.
6789 trace_clock= [FTRACE] Set the clock used for tracing events
6791 local - Use the per CPU time stamp counter
6795 global - Event time stamps are synchronize across
6798 counter - Simple counting of events (1, 2, ..)
6802 uptime - Use jiffies as the time stamp.
6803 perf - Use the same clock that perf uses.
6804 mono - Use ktime_get_mono_fast_ns() for time stamps.
6805 mono_raw - Use ktime_get_raw_fast_ns() for time
6807 boot - Use ktime_get_boot_fast_ns() for time stamps.
6811 trace_event=[event-list]
6812 [FTRACE] Set and start specified trace events in order
6813 to facilitate early boot debugging. The event-list is a
6814 comma-separated list of trace events to enable. See
6817 trace_instance=[instance-info]
6823 Events can be enabled at the time the instance is created
6842 traceoff - Have the tracing instance tracing disabled after it is created.
6843 traceprintk - Have trace_printk() write into this trace instance
6865 memory may not be the same location each time, which will not preserve
6882 trace_options=[option-list]
6884 The option-list is a comma delimited list of options
6898 trace_trigger=[trigger-list]
6900 Set a trigger on top of a specific event, with an optional
6927 This option can also be set at run time via the sysctl
6935 See Documentation/admin-guide/mm/transhuge.rst
6943 - "tpm"
6944 - "tee"
6945 - "caam"
6946 - "dcp"
6956 - "kernel"
6957 - the same value as trusted.source: "tpm" or "tee"
6958 - "default"
6979 high-resolution timer mode on older hardware, and in
6982 Used to run time disable IRQ_TIME_ACCOUNTING on any
7015 on - Enable TSX on the system. Although there are
7018 several previous speculation-related CVEs, and
7022 off - Disable TSX on the system. (Note that this
7030 auto - Disable TSX if X86_BUG_TAA is present,
7035 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7041 Similar to Micro-architectural Data Sampling (MDS)
7056 full - Enable TAA mitigation on vulnerable CPUs
7059 full,nosmt - Enable TAA mitigation and disable SMT on
7062 vulnerable to cross-thread TAA attacks.
7063 off - Unconditionally disable TAA mitigation
7065 On MDS-affected machines, tsx_async_abort=off can be
7077 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7083 See also Documentation/input/devices/joystick-parport.rst
7085 udbg-immortal [PPC] When debugging early kernel crashes that
7091 Set number of hash buckets for UDP/UDP-Lite connections
7093 uhci-hcd.ignore_oc=
7095 Some badly-designed motherboards generate lots of
7097 anything. Set this parameter to avoid log spamming.
7104 unwind_debug [X86-64,EARLY]
7112 (default -1 = authorized (same as 1),
7117 [USB] The autosuspend time delay (in seconds) used
7118 for newly-detected USB devices (default 2). This
7119 is the time required before an idle device will be
7120 autosuspended. Devices for which the delay is set
7124 [USB] Set to log all usbfs traffic (default 0 = off).
7131 [USB] Set to cycle leds on hubs (default 0 = off).
7146 [USB] Specifies timeout for the initial 64-byte
7153 [USB] A list of quirk entries to augment the built-in
7156 VendorID:ProductID:Flags. The IDs are 4-digit hex
7157 numbers and Flags is a set of letters. Each letter
7158 will change the built-in quirk; setting it if it is
7159 clear and clearing it if it is set. The letters have
7163 a 255-byte read);
7167 Set-Interface requests);
7186 (bInterval-1).
7224 usb-storage.delay_use=
7231 usb-storage.quirks=
7233 override the built-in unusual_devs list. List
7236 and Product ID values (4-digit hex numbers) and
7237 Flags is a set of characters, each corresponding
7238 to a common usb-storage quirk flag as follows:
7252 240 sectors at a time, uas only);
7264 than 64 sectors = 32 KB at a time,
7276 t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
7280 medium is write-protected).
7289 1 - undefined instruction events
7290 2 - system calls
7291 4 - invalid data aborts
7292 8 - SIGSEGV faults
7293 16 - SIGBUS faults
7309 vdso32= [X86] Control the 32-bit vDSO
7310 vdso32=1: enable 32-bit VDSO
7311 vdso32=0 or vdso32=2: disable 32-bit VDSO
7314 details. If CONFIG_COMPAT_VDSO is set, the default is
7321 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
7328 If set to 1, on receiving an ACPI notify event
7331 the allocated input device. If set to 0, video driver
7352 vga= [BOOT,X86-32] Select a particular video mode
7354 Documentation/admin-guide/svga.rst.
7363 interface is meant to allow for selectively
7368 P Enable page structure init time poisoning
7369 - Disable all of the above options
7393 vsyscall= [X86-64,EARLY]
7396 code). Most statically-linked binaries and older
7420 see VGA-softcursor.txt. Default: 2 = underline.
7425 This is a 16-member array composed of values
7426 ranging from 0-255.
7431 This is a 16-member array composed of values
7432 ranging from 0-255.
7437 This is a 16-member array composed of values
7438 ranging from 0-255.
7443 Set system-wide default UTF-8 mode for all tty's.
7444 Default is 1, i.e. UTF-8 mode is enabled for all
7449 Format=<-1|0|1>
7450 Set system-wide default for whether a cursor
7451 is shown on new VTs. Default is -1,
7456 vt.italic= [VT] Default color for italic text; 0-15.
7459 vt.underline= [VT] Default color for underlined text; 0-15.
7463 see Documentation/watchdog/watchdog-parameters.rst
7464 or other driver-specific files in the
7469 Set the hard lockup detector stall duration
7471 threshold is set to twice the value. A value of 0
7478 Format: <cpu-list>
7499 Per-cpu work items which run for longer than this
7502 them from noticeably delaying other per-cpu work
7505 If CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel
7511 If CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel
7520 Per-cpu workqueues are generally preferred because
7522 locality; unfortunately, per-cpu workqueues tend to
7525 Enabling this makes the per-cpu workqueues which
7539 Documentation/core-api/workqueue.rst.
7552 forces round-robin CPU selection to flush out
7560 on - Enable writecombine, use WUC for ioremap_wc()
7561 off - Disable writecombine, use SUC for ioremap_wc()
7563 x2apic_phys [X86-64,APIC,EARLY] Use x2apic physical mode instead of
7567 xen_512gb_limit [KNL,X86-64,XEN]
7577 ide-disks -- unplug primary master IDE devices
7578 aux-ide-disks -- unplug non-primary-master IDE devices
7579 nics -- unplug network devices
7580 all -- unplug all emulated devices (NICs and IDE disks)
7581 unnecessary -- unplugging emulated devices is
7584 never -- do not unplug even if version check succeeds
7598 Select whether to always use non-faulting (safe) MSR
7618 xen_timer_slop= [X86-64,XEN,EARLY]
7619 Set the timer slop (in nanoseconds) for the virtual Xen
7626 The time (in seconds) to wait before giving up to boot
7637 After which time (jiffies) the event handling loop
7643 preferred over the 2-level event handling, as it is
7660 xive.store-eoi=off [PPC]
7666 xhci-hcd.quirks [USB,KNL]