Lines Matching +full:ring +full:- +full:fall +full:- +full:db +full:- +full:ms
5 force -- enable ACPI if default was off
6 on -- enable ACPI but allow fallback to DT [arm64,riscv64]
7 off -- disable ACPI if default was on
8 noirq -- do not use ACPI for IRQ routing
9 strict -- Be less tolerant of platforms that are not
11 rsdt -- prefer RSDT over (default) XSDT
12 copy_dsdt -- copy DSDT to memory
26 If set to vendor, prefer vendor-specific driver
58 Documentation/firmware-guide/acpi/debug.rst for more information about
116 Format: <byte> or <bitmap-list>
119 Disable auto-serialization of AML methods
122 auto-serialization feature.
140 Ignore the ACPI-based watchdog interface (WDAT) and let
161 acpi_osi=! # disable all built-in OS vendor
163 acpi_osi=!! # enable all built-in OS vendor
225 For broken nForce2 BIOS resulting in XT-PIC timer.
234 as soon as the kernel's real-mode entry point is called.
272 See Documentation/sound/alsa-configuration.rst
279 align_va_addr= [X86-64]
284 CPU-intensive style benchmark, and it can vary highly in
287 32: only for 32-bit processes
288 64: only for 64-bit processes
289 on: enable for both 32- and 64-bit processes
290 off: disable for both 32- and 64-bit processes
300 Allow execve() of 32-bit applications and setting of the
302 subset of the CPUs support 32-bit EL0. When this
303 parameter is present, the set of CPUs supporting 32-bit
305 and hot-unplug operations may be restricted.
307 See Documentation/arch/arm64/asymmetric-32bit.rst for more
310 amd_iommu= [HW,X86-64]
313 fullflush - Deprecated, equivalent to iommu.strict=1
314 off - do not initialize any AMD IOMMU found in
316 force_isolation - Force device isolation for all
321 force_enable - Force enable the IOMMU on platforms known
324 pgtbl_v1 - Use v1 page table for DMA-API (Default).
325 pgtbl_v2 - Use v2 page table for DMA-API.
326 irtcachedis - Disable Interrupt Remapping Table (IRT) caching.
328 amd_iommu_dump= [HW,X86-64]
334 amd_iommu_intr= [HW,X86-64]
337 legacy - Use legacy interrupt remapping mode.
338 vapic - Use virtual APIC mode, which allows IOMMU
340 This mode requires kvm-amd.avic=1.
377 Power management functions (SPARCstation-4/5 + deriv.)
379 Disable APC CPU standby support. SPARCstation-Fox does
380 not play well with APC CPU idle - disable it if you have
387 when initialising the APIC and IO-APIC components.
388 For X86-32, this can also be used to specify an APIC
411 0 -- disable.
412 1 -- enable.
415 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
448 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
457 audit= [KNL] Enable the audit sub-system
459 0 | off - kernel audit is disabled and can not be
461 unset - kernel audit is initialized but disabled and
463 1 | on - kernel audit is initialized and partially
476 0 - Disable the BAU.
477 1 - Enable the BAU.
478 unset - Disable the BAU.
505 See Documentation/block/cmdline-partition.rst
518 See Documentation/admin-guide/bootconfig.rst
523 bttv.pll= See Documentation/admin-guide/media/bttv.rst
532 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
551 inclusive. See arch/mips/include/asm/pgtable-bits.h
561 - foo isn't auto-mounted if you mount all cgroups in
563 - foo isn't visible as an individually mountable
565 - if foo is an optional feature then the feature is
571 Specifying "pressure" disables per-cgroup pressure
585 nosocket -- Disable socket memory accounting.
586 nokmem -- Disable kernel memory accounting.
587 nobpf -- Disable BPF memory accounting.
592 0 -- check protection applied by kernel (includes
594 1 -- check protection requested by application.
606 numbers X. Note the Linux-specific bits are not necessarily
607 stable over kernel options, but the vendor-specific
627 force such clocks to be always-on nor does it reserve
631 information, see Documentation/driver-api/clk.rst.
633 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
650 [X86-32] pit,hpet,tsc;
657 [X86-64] hpet,tsc
663 architected timer so that code using WFE-based polling
677 clocksource-wdtest.holdoff= [KNL]
683 cma=nn[MG]@[start[MG][-end[MG]]]
694 Sets the size of kernel per-numa memory area for
696 per-numa CMA altogether. And If this option is not
698 With per-numa CMA enabled, DMA users on node nid will
725 com20020= [HW,NET] ARCnet - COM20020 chipset
729 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
733 ARCnet - COM90xx chipset (memory-mapped buffers)
762 See Documentation/admin-guide/serial-console.rst for more
772 Start an early, polled-mode console on the 8250/16550
775 MMIO inter-register address stride is either 8-bit
776 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
780 the h/w is not re-initialized.
807 syscall, or to executing "dmesg -S --raw" or to reading
831 disable the cpuidle sub-system
837 disable the cpufreq sub-system
845 [X86] Delay for N microsec between assert and de-assert
857 Run kdump after running panic-notifiers and dumping
870 [KNL, X86-64, ARM64, RISCV] Select a region under 4G first, and
871 fall back to reserve region above 4G when '@offset'
873 See Documentation/admin-guide/kdump/kdump.rst for further details.
878 start-[end] where start and end are both
880 Documentation/admin-guide/kdump/kdump.rst for an example.
883 [KNL, X86-64, ARM64, RISCV] range could be above 4G.
890 [KNL, X86-64, ARM64, RISCV] range under 4G. When crashkernel=X,high
895 low memory is needed to make sure DMA buffers for 32-bit
899 --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
900 --> arm64: 128MiB
901 --> riscv: 128MiB
909 [KNL] Disable crypto self-tests
917 csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
932 See also Documentation/input/devices/joystick-parport.rst
945 [KNL] verbose locking self-tests
948 self-tests.
950 (no extra messages), setting it to -1 (all bits set)
951 will print _a_lot_ more information - normally only
986 Format: { on, no-mount, off }
988 no-mount:
993 get a -EPERM as result when trying to register files
997 Default value is set in build-time with a kernel configuration.
1009 Documentation/admin-guide/mm/hugetlbpage.rst.
1023 delayacct [KNL] Enable per-task delay accounting
1066 causes the kernel to fall back to 256MB segments which
1118 entries for DMA-API debugging code. One entry is
1119 required per DMA-API allocation. Use this if the
1120 DMA-API debugging code disables itself because the
1124 With this option the DMA-API debugging driver
1148 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
1162 Generic built-in EDID data sets are used, if one of
1167 available in Documentation/admin-guide/edid.rst. An EDID
1179 Control how the dt_cpu_ftrs device-tree binding is
1182 off: Do not use it, fall back to legacy cpu table.
1189 what data is available or for reverse-engineering.
1194 Documentation/admin-guide/dynamic-debug-howto.rst
1205 determined by stdout-path property in device tree's
1210 Start an early, polled-mode console on a Cadence
1221 Start an early, polled-mode console on the 8250/16550
1223 MMIO inter-register address stride is either 8-bit
1224 (mmio) or 32-bit (mmio32 or mmio32be).
1234 Start an early, polled-mode console on a pl011 serial
1238 the driver will use only 32-bit accessors to read/write
1247 Start an early, polled-mode console on a meson serial
1253 Start an early, polled-mode console on an msm serial
1259 Start an early, polled-mode console on an msm serial
1265 Start an early, polled-mode console on a serial port
1271 Start an early, polled-mode console on a serial port
1277 Use RISC-V SBI (Supervisor Binary Interface) for early
1295 Start an early, polled-mode console on a lantiq serial
1309 Start an early, polled-mode, output-only console on the
1314 Start an early, polled-mode console on the
1320 Start an early, polled-mode console on a Qualcomm
1328 coherent non-x86 systems that use system memory for
1428 attribute is added to range 0x100000000-0x180000000 and
1429 0x10a0000000-0x1120000000.
1433 range 0x240000000-0x43fffffff.
1445 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1462 elanfreq= [X86-32]
1470 See Documentation/admin-guide/kdump/kdump.rst for details.
1486 0 -- permissive (log only, no denials).
1487 1 -- enforcing (deny and log).
1519 See also Documentation/fault-injection/.
1523 See Documentation/admin-guide/sysctl/net.rst for
1527 See Documentation/admin-guide/blockdev/floppy.rst.
1530 [IA-64] Avoid check_sal_cache_flush which may hang on
1535 forcepae [X86-32]
1549 ftrace ring buffer that can be read at:
1571 ftrace_filter=[function-list]
1573 tracer at boot up. function-list is a comma-separated
1578 ftrace_notrace=[function-list]
1580 function-list. This list can be changed at run time
1584 ftrace_graph_filter=[function-list]
1587 function-list is a comma-separated list of functions
1591 ftrace_graph_notrace=[function-list]
1593 function-list. This list is a comma-separated list of
1613 off -- Don't create device links from firmware info.
1614 permissive -- Create device links from firmware info
1617 on -- Create device links from firmware info and use it
1619 rpm -- Like "on", but also use to order runtime PM.
1632 strict -- Default. Continue waiting on consumers to
1634 timeout -- Give up waiting on consumers and call
1644 See also Documentation/input/devices/joystick-parport.rst
1648 gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
1672 gcov_persist= [GCOV] When non-zero (default), profiling data for
1682 gpio-mockup.gpio_mockup_ranges
1685 gpio-mockup.gpio_mockup_named_lines
1717 against bounds-checking flaws in the kernel's
1723 [KNL] Should the hard-lockup detector generate
1729 for 64-bit NUMA, off otherwise.
1732 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1739 corresponding firmware-first mode error processing
1749 during restoration read-only).
1775 hpet= [X86-32,HPET] option to control HPET usage
1792 number of pages to allocate per-node can be specified.
1793 See also Documentation/admin-guide/mm/hugetlbpage.rst.
1804 Documentation/admin-guide/mm/hugetlbpage.rst.
1815 boot-time allocation of gigantic hugepages is skipped.
1843 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1849 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1866 (disabled by default, and as a pre-condition
1868 i8042.direct [HW] Put keyboard port into non-translated mode
1882 suspend-to-ram transitions, only during s2r
1906 -1 -- never invert brightness
1907 0 -- machine default
1908 1 -- force brightness inversion
1922 idle=nomwait: Disable mwait for CPU C-states
1950 legacy only accept legacy-NaN binaries, if supported
1952 2008 only accept 2008-NaN binaries, if supported
1961 'relaxed' straps the emulator for both legacy-NaN and
1962 2008-NaN, whereas 'strict' enables legacy-NaN only on
1971 Ignore loglevel setting - this will print /all/
2038 Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
2039 "ima-sigv2" }
2040 Default: "ima-ng"
2072 initcall_blacklist= [KNL] Do not execute a comma-separated list of
2073 initcall functions. Useful for debugging built-in
2118 0 -- basic integrity auditing messages. (Default)
2119 1 -- additional integrity auditing messages.
2147 could harm performance of some high-throughput
2155 0 disables intel_idle and fall back on acpi_idle.
2156 1 to 9 specify maximum depth of C-state.
2165 algorithms for p-state selection. There are two
2166 P-state selection algorithms provided by
2169 on whether or not the hardware managed P-states
2176 used along with the hardware-managed P-states (HWP)
2180 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2181 instead of acpi-cpufreq may disable platform features, such
2183 P-States information being indicated to OSPM and therefore
2186 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2199 Allow per-logical-CPU P-State performance control limits using
2202 intremap= [X86-64, Intel-IOMMU]
2207 BIOS x2APIC opt-out request will be ignored
2231 0 - Try to allocate a 32-bit DMA address first, before
2233 1 - Allocate directly from the full usable range,
2235 greater than 32-bit addressing.
2239 0 - Lazy mode.
2243 Will fall back to strict mode if not supported by
2245 1 - Strict mode.
2248 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2250 legacy driver-specific options takes precedence.
2255 0 - Use IOMMU translation for DMA.
2256 1 - Bypass the IOMMU for DMA.
2257 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2259 io7= [HW] IO7 for Marvel-based Alpha systems
2274 See Documentation/admin-guide/nfs/nfsroot.rst.
2298 Enables support for pseudo-NMIs in the kernel. This
2317 [Deprecated - use cpusets instead]
2318 Format: [flag-list,]<cpu-list>
2349 "number of CPUs in system - 1".
2375 The format of <cpu-list> is described above.
2379 ivrs_ioapic [HW,X86-64]
2380 Provide an override to the IOAPIC-ID<->DEVICE-ID
2384 For example, to map IOAPIC-ID decimal 10 to
2390 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2393 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2397 ivrs_hpet [HW,X86-64]
2398 Provide an override to the HPET-ID<->DEVICE-ID
2402 For example, to map HPET-ID decimal 10 to
2408 * To map HPET-ID decimal 0 to PCI device 00:14.0
2411 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2415 ivrs_acpihid [HW,X86-64]
2416 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2420 For example, to map UART-HID:UID AMD0020:0 to
2426 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2429 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2450 kernelcore= [KNL,X86,IA-64,PPC]
2453 the kernel for non-movable allocations. The requested
2463 subsystem. Note that allocations like PTEs-from-HighMem
2471 for non-movable allocations and remaining memory is used
2482 gdb or control-c on the dbgp connection. When
2483 not using this parameter you use sysrq-g to break into
2488 or a supported polling keyboard driver (non-usb).
2515 Configure the RouterBoard 532 series on-chip
2518 kmemleak= [KNL] Boot-time kmemleak enable/disable
2524 kprobe_event=[probe-list]
2526 The probe-list is a semicolon delimited list of probe
2556 execution by eliminating the write-protection faults
2601 back to huge pages. If the value is a non-zero N, KVM will
2606 kvm-amd.nested= [KVM,AMD] Control nested virtualization feature in
2609 kvm-amd.npt= [KVM,AMD] Control KVM's use of Nested Page Tables,
2610 a.k.a. Two-Dimensional Page Tables. Default is 1
2614 kvm-arm.mode=
2619 nvhe: Standard nVHE-based mode, without support for
2622 protected: nVHE-based mode with support for guests whose
2625 nested: VHE-based mode with support for nested
2634 kvm-arm.vgic_v3_group0_trap=
2635 [KVM,ARM] Trap guest accesses to GICv3 group-0
2638 kvm-arm.vgic_v3_group1_trap=
2639 [KVM,ARM] Trap guest accesses to GICv3 group-1
2642 kvm-arm.vgic_v3_common_trap=
2646 kvm-arm.vgic_v4_enable=
2658 kvm-intel.ept= [KVM,Intel] Control KVM's use of Extended Page Tables,
2659 a.k.a. Two-Dimensional Page Tables. Default is 1
2663 kvm-intel.emulate_invalid_guest_state=
2665 state. Ignored if kvm-intel.enable_unrestricted_guest=1,
2671 kvm-intel.flexpriority=
2676 kvm-intel.nested=
2680 kvm-intel.unrestricted_guest=
2686 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2687 CVE-2018-3620.
2698 kvm-intel.vpid= [KVM,Intel] Control KVM's use of Virtual Processor
2718 on - enable the interface for the mitigation
2783 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2789 lapic [X86-32,APIC] Enable the local APIC even if BIOS
2793 value for LAPIC timer one-shot implementation. Default
2816 libata.force= [LIBATA] Force configurations. The format is a comma-
2828 first fan-out link behind PMP device. It does not
2842 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2849 * rstonce: only attempt one reset during hot-unplug
2852 * [no]dbdelay: Enable or disable the extra 200ms delay
2931 Set the number of locking read-acquisition kthreads.
2936 Set the number of locking write-acquisition kthreads.
2939 Set time (s) after boot for CPU-hotplug testing.
2942 Set time (s) between CPU-hotplug operations, or
2943 zero to disable CPU-hotplug testing.
2946 Set task-shuffle interval (jiffies). Shuffling
2947 tasks allows some CPUs to go into dyntick-idle
2952 is useful for hands-off automated testing.
2968 Run the write-side locktorture kthreads at
2969 sched_set_fifo() real-time priority.
2989 7 (KERN_DEBUG) debug-level messages
2991 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
2999 logo.nologo [FB] Disables display of the built-in Linux logo.
3017 an IEEE 1284-compliant printer is attached; if
3023 time-consuming boot-time autodetection (up to 250 ms per
3044 machvec= [IA-64] Force the use of a particular machine-vector
3050 Example: machtype=lemote-yeeloong-2f-7inch
3052 max_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory greater
3065 (loop.max_loop) unconditionally pre-created at init time. The default
3068 devices can be requested on-demand with the
3069 /dev/loop-control interface.
3071 mce [X86-32] Machine Check Exception
3073 mce=option [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
3076 See Documentation/admin-guide/md.rst.
3083 Control mitigation for the Micro-architectural Data
3098 full - Enable MDS mitigation on vulnerable CPUs
3099 full,nosmt - Enable MDS mitigation and disable
3101 off - Unconditionally disable MDS mitigation
3103 On TAA-affected machines, mds=off can be prevented by
3112 For details see: Documentation/admin-guide/hw-vuln/mds.rst
3126 [ARC,MICROBLAZE] - the limit applies only to low memory,
3129 [ARM64] - only limits memory covered by the linear
3142 [ARM,MIPS] - override the memory layout reported by
3149 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
3156 per-device physically contiguous DMA buffers.
3164 See Documentation/admin-guide/mm/memory-hotplug.rst.
3189 Example: Exclude memory from 0x18690000-0x1869ffff
3203 memmap=<size>%<offset>-<oldtype>+<newtype>
3205 from <oldtype> to <newtype>. If "-<oldtype>" is left
3220 repeatable BIOS-originated corruption always
3264 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
3270 Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
3274 s2idle - Suspend-To-Idle
3275 shallow - Power-On Suspend or equivalent (if supported)
3276 deep - Suspend-To-RAM or equivalent (if supported)
3277 See Documentation/admin-guide/pm/sleep-states.rst.
3279 mfgpt_irq= [IA-32] Specify the IRQ to use for the
3280 Multi-Function General Purpose Timers on AMD Geode
3283 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
3295 min_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory below this
3302 0 - The attached screen is the 3.5" TFT
3303 1 - The attached screen is the 7" TFT
3304 2 - The VGA Shield is attached (1024x768)
3308 b - Enable backlight. The TFT backlight pin will be
3312 c - Enable the s3c camera interface.
3313 t - Reserved for enabling touchscreen support. The
3317 https://repo.or.cz/w/linux-2.6/mini2440.git
3322 arch-independent options, each of which is an
3323 aggregation of existing arch-specific options.
3351 ssbd=force-off [ARM64]
3364 have other ways of avoiding SMT-based attacks.
3399 full - Enable mitigation on vulnerable CPUs
3401 full,nosmt - Enable mitigation and disable SMT on
3404 off - Unconditionally disable mitigation
3417 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3447 module_blacklist= [KNL] Do not load a comma-separated list of
3461 movablecore= [KNL,X86,IA-64,PPC]
3472 movable_node [KNL] Boot-time switch to make hotplugable memory
3479 Format: <name>,<region-number>,<size>,<offset>
3482 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3490 See arch/arm/mach-s3c/mach-jive.c
3526 something different and driver-specific.
3559 [NFS] enable 64-bit inode numbers.
3560 If zero, the NFS client will fake up a 32-bit inode
3562 of returning the full 64-bit number.
3563 The default is to return 64-bit inode numbers.
3593 will be autodetected by the client, and it will fall
3598 [NFS4] Specify an additional fixed unique ident-
3629 driver. A non-zero value sets the minimum interval
3634 server-to-server copies for which this server is
3646 server-to-server copy, knfsd temporarily mounts
3653 See Documentation/admin-guide/nfs/nfsroot.rst.
3655 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3656 See Documentation/admin-guide/nfs/nfsroot.rst.
3659 See Documentation/admin-guide/nfs/nfsroot.rst.
3663 NMI stack-backtrace request.
3672 0 - turn hardlockup detector in nmi_watchdog off
3673 1 - turn hardlockup detector in nmi_watchdog on
3685 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3689 no4lvl [RISCV] Disable 4-level and 5-level paging modes. Forces
3690 kernel to use 3-level paging instead.
3692 no5lvl [X86-64,RISCV] Disable 5-level paging mode. Forces
3693 kernel to use 4-level paging instead.
3696 caches in the slab allocator. Saves per-node memory,
3733 no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel.
3735 noexec [IA-64]
3737 noexec32 [X86-64]
3738 This affects only 32-bit executables.
3739 noexec32=on: enable non-executable mappings (default)
3741 noexec32=off: disable non-executable mappings
3752 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3754 legacy floating-point registers on task switch.
3756 nohalt [IA-64] Tells the kernel not to use the power saving
3758 power-consumption. On the positive side, it reduces
3759 interrupt wake-up latency, which may improve performance
3761 real-time systems.
3771 compared. However, if this command-line option is
3812 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
3814 [Deprecated - use intremap=off]
3816 nointroute [IA-64]
3822 noirqdebug [X86-32] Disables the code which attempts to detect and
3827 nojitter [IA-64] Disables jitter checking for ITC timers.
3834 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
3837 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
3839 nolapic [X86-32,APIC] Do not enable or use the local APIC.
3841 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
3843 nomca [IA-64] Disable machine check abort handling
3845 nomce [X86-32] Disable Machine Check Exception
3847 nomfgpt [X86-32] Disable Multi-Function General Purpose
3853 not load if they could possibly displace the pre-
3856 perform display-mode changes or accelerated rendering.
3869 nopcid [X86-64] Disable the PCID cpu feature.
3874 nopti [X86-64]
3890 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
3896 nosbagart [IA-64]
3898 no-scroll [VGA] Disables scrollback.
3899 This is required for the Braillex ib80-piezo Braille
3902 nosgx [X86-64,SGX] Disables Intel SGX kernel support.
3922 nosoftlockup [KNL] Disable the soft-lockup detector.
3927 nospectre_bhb [ARM64] Disable all mitigations for Spectre-BHB (branch
3940 no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES] Disable paravirtualized
3950 [PPC] Don't flush the L1-D cache after accessing user data.
3963 no-vmw-sched-clock
3968 soft-lockup and NMI watchdog (hard-lockup).
3972 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
3980 enabling legacy floating-point and sse state.
3983 register states. The kernel will fall back to use
3991 form of xsave area. The kernel will fall back to use
4006 nptcg= [IA-64] Override max number of concurrent global TLB
4015 n. So during boot up some boot time memory for per-cpu
4016 variables need be pre-allocated for later physical cpu
4031 See Documentation/admin-guide/sysctl/vm.rst for details.
4034 See Documentation/core-api/debugging-via-ohci1394.rst for more
4037 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
4038 Rather than timing out after 20 ms if an EC
4049 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
4053 boundary - index of last SLC block on Flex-OneNAND.
4055 lock - Configure if Flex-OneNAND boundary should be locked.
4069 running on a platform with a direct-mapped memory-side
4075 page_owner= [KNL] Boot-time page_owner enabling option.
4081 page_poison= [KNL] Boot-time parameter changing the state of
4108 See Documentation/admin-guide/tainted-kernels.rst for
4160 Set to non-zero to probe primary and secondary ISA
4166 Set to non-zero if a chip is present that snoops speed
4214 Set to non-zero to probe tertiary and further ISA
4230 Set to non-zero to probe QDI controllers. By default
4235 Set to non-zero to probe Winbond controllers. Use
4282 bios [X86-32] force use of PCI BIOS, don't access
4284 has a non-standard PCI host bridge.
4285 nobios [X86-32] disallow use of PCI BIOS, only direct
4291 data in IO port 0xCFC, both 32-bit).
4293 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
4294 the function, IO port 0xCFA, also 8-bit, sets
4296 through ports 0xC000-0xCFFF).
4303 root domains (aka PCI segments, in ACPI-speak).
4311 disable the use of MSI interrupts system-wide.
4316 primary IO-APIC for bridges that cannot disable
4323 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
4347 F0000h-100000h range.
4352 assign-busses [X86] Always assign all PCI bus
4373 <linux-pci@vger.kernel.org>.
4377 a bug to <linux-pci@vger.kernel.org>.
4389 bfsort Sort PCI devices into breadth-first order.
4392 nobfsort Don't sort PCI devices into breadth-first order.
4394 tuning and use the BIOS-configured MPS defaults.
4404 configuration allows peer-to-peer DMA between
4407 that hot-added devices will work.
4422 A PCI-PCI bridge can be specified if resource
4428 for 4096-byte alignment.
4430 end-to-end CRC checking). Only effective if
4461 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4497 dpc-native Use native PCIe service for DPC only. May
4514 Keep all power-domains already enabled by bootloader on,
4531 pirq= [SMP,APIC] Manual mp-table setup
4532 See Documentation/arch/x86/i386/IO-APIC.rst.
4536 See also Documentation/admin-guide/parport.rst.
4555 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4564 { on | off | curr | res | no-curr | no-res }
4604 none - Limited to cond_resched() calls
4605 voluntary - Limited to cond_resched() and might_sleep() calls
4606 full - Any section that isn't explicitly preempt disabled
4609 print-fatal-signals=
4615 coredump - etc.
4618 you might want to try "ulimit -i unlimited".
4630 or lockdep-detected issues (only if lock debug is on).
4639 on - unlimited logging to /dev/kmsg from userspace
4640 off - logging to /dev/kmsg disabled
4641 ratelimit - ratelimit the logging
4652 - 'always': traditional behavior always allows mem overrides.
4653 - 'ptrace': only allow mem overrides for active ptracers.
4654 - 'never': never allow mem overrides.
4658 Limit processor to maximum C-state
4662 Ignore the _CST method to determine C-states,
4669 Param: "schedule" - profile schedule points.
4670 Param: "kvm" - profile VM exits.
4671 Param: <number> - step/bucket size as a power of 2 for
4700 pti= [X86-64] Control Page Table Isolation of user and
4705 on - unconditionally enable
4706 off - unconditionally disable
4707 auto - kernel detects whether your CPU model is
4713 [KNL] Number of legacy pty's. Overwrites compiled-in
4725 See Documentation/admin-guide/md.rst.
4728 See Documentation/admin-guide/blockdev/ramdisk.rst.
4747 cross-syscall address exposures. This is only
4753 ras=option[,option,...] [KNL] RAS-specific options
4759 rcu_nocbs[=cpu-list]
4764 enable the no-callback CPU mode, which prevents
4769 "p" for RCU-preempt, "s" for RCU-sched, and "g"
4773 and real-time workloads. It can also improve
4777 list of CPUs is set to no-callback mode from boot.
4781 no-callback mode from boot but the mode may be
4792 This improves the real-time response for the
4809 RCU grace-period cleanup.
4813 RCU grace-period initialization.
4817 RCU grace-period pre-initialization, that is,
4818 the propagation of recent CPU-hotplug changes up
4822 Set delay from grace-period initialization to
4835 soliciting quiescent-state help from
4847 Set the SCHED_FIFO priority of the RCU per-CPU
4850 and for the RCU grace-period kthreads (rcu_bh,
4852 set, valid values are 1-99 and the default is 1
4853 (the least-favored priority). Otherwise, when
4854 RCU_BOOST is not set, valid values are 0-99 and
4855 the default is zero (non-realtime operation).
4860 On callback-offloaded (rcu_nocbs) CPUs,
4863 use of the ->nocb_bypass list. However, in the
4864 common non-flooded case, RCU queues directly to
4865 the main ->cblist in order to avoid the extra
4866 overhead of the ->nocb_bypass list and its lock.
4868 a single jiffy, RCU pre-queues the callbacks into
4869 the ->nocb_bypass queue. The definition of "too
4878 batch limiting is re-enabled.
4882 RCU's force-quiescent-state scan will aggressively
4890 Set the page-cache refill delay (in milliseconds)
4891 in response to low-memory conditions. The range
4895 Set the shift-right count to use to compute
4896 the callback-invocation batch limit bl from
4903 Please note that this callback-invocation batch
4904 limit applies only to non-offloaded callback
4913 cache-to-cache transfer latencies.
4919 and for NUMA systems with large remote-access
4935 the wakeup overhead on the global grace-period
4937 each group's NOCB grace-period kthread.
4940 Cause the grace-period kthread to get an extra
4942 it should at force-quiescent-state time.
4955 this specifies an rcu_read_unlock()-time delay
4959 of RCU-protected pointers after the relevant
4969 per-CPU rcuc kthreads. Defaults to a non-zero
4979 grace-period primitives such as call_rcu().
4990 grace-period primitives.
4993 Set test-start holdoff period. The purpose of
5011 Test the double-argument variant of kfree_rcu().
5013 rcuscale.kfree_rcu_test_single, both the single-
5014 and double-argument variants are tested.
5017 Test the single-argument variant of kfree_rcu().
5019 rcuscale.kfree_rcu_test_double, both the single-
5020 and double-argument variants are tested.
5034 does not affect the data-collection interval,
5039 Set number of RCU readers. The value -1 selects
5041 "n" less than -1 selects N-n+1, where N is again
5042 the number of CPUs. For example, -2 selects N
5043 (the number of CPUs), -3 selects N+1, and so on.
5044 A value of "n" less than or equal to -N selects
5057 complete. This is useful for hands-off automated
5064 Write-side holdoff between grace periods,
5069 Additional write-side holdoff between grace
5087 for RCU grace-period forward-progress testing
5094 Specify the fraction of a CPU-stall-warning
5095 period to do tight-loop forward-progress testing.
5099 forward-progress tests.
5103 need_resched() during tight-loop forward-progress
5107 Use conditional/asynchronous update-side
5111 Use expedited update-side primitives, if available.
5114 Use normal (non-expedited) asynchronous
5115 update-side primitives, if available.
5118 Use normal (non-expedited) synchronous
5119 update-side primitives, if available. If all
5123 they are all non-zero.
5131 Leak an RCU-protected pointer out of the reader.
5146 Set number of RCU callback-offload togglers.
5151 callback-offload toggling attempts.
5154 Set number of RCU readers. The value -1 selects
5155 N-1, where N is the number of CPUs. A value
5156 "n" less than -1 selects N-n-2, where N is again
5157 the number of CPUs. For example, -2 selects N
5158 (the number of CPUs), -3 selects N+1, and so on.
5161 Enable debug-object double-call_rcu() testing.
5164 Set time (s) after boot for CPU-hotplug testing.
5167 Set time (jiffies) between CPU-hotplug operations,
5168 or zero to disable CPU-hotplug testing.
5171 Set the number of read-then-exit kthreads used
5173 task-exit processing.
5176 The number of times in a given read-then-exit
5177 episode that a set of read-then-exit kthreads
5182 read-then-exit testing episodes.
5185 Set task-shuffle interval (s). Shuffling tasks
5186 allows some CPUs to go into dyntick-idle mode
5191 is useful for hands-off automated testing.
5200 any other stall-related activity. Note that
5206 in scheduling-while-atomic splats.
5219 grace-period kthread to test RCU CPU stall
5245 Test RCU's dyntick-idle handling. See also the
5294 Use expedited grace-period primitives, for
5298 real-time latency, and degrade energy efficiency.
5302 Use only normal grace-period primitives,
5305 real-time latency, CPU utilization, and
5307 increased grace-period latency. This parameter
5314 only normal grace-period primitives. No effect
5320 post-boot attempt at an expedited RCU grace
5321 period to instead use normal non-expedited
5322 grace-period processing.
5330 set to the default value of -1.
5333 Set the minimum number of callback-queuing-time
5334 lock-contention events per jiffy required to
5335 cause the RCU Tasks flavors to switch to per-CPU
5338 the default value of -1.
5343 of -1 allows this to be automatically (and
5351 number avoids disturbing real-time workloads,
5356 cancel laziness on that CPU. Use -1 to disable
5366 only printed prior to the stall-warning message
5422 force - Override the decision by the kernel to hide the
5450 Set test-start holdoff period. The purpose of
5459 but the default has already reduced the per-pass
5464 Set number of readers. The default value of -1
5473 Set the read-side critical-section duration,
5477 Specify the read-protection implementation to test.
5496 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
5504 reservetop= [X86-32]
5521 See Documentation/power/swsusp-and-swap-files.rst
5536 AMD-based UNRET and IBPB mitigations alone do not stop
5538 sibling threads. For that reason, STIBP is used on pro-
5542 off - no mitigation
5543 auto - automatically select a migitation
5544 auto,nosmt - automatically select a mitigation,
5548 ibpb - On AMD, mitigate short speculation
5553 ibpb,nosmt - Like "ibpb" above but will disable SMT
5557 unret - Force enable untrained return thunks,
5558 only effective on AMD f15h-f17h based
5560 unret,nosmt - Like unret, but will disable SMT when STIBP
5585 [KNL] Disable ring 3 MONITOR/MWAIT feature on supported
5595 ro [KNL] Mount root device read-only on boot
5598 on Mark read-only kernel memory as read-only (default).
5599 off Leave read-only kernel memory writable for debugging.
5600 full Mark read-only kernel memory and aliases as read-only
5606 debug-uart get routed to the D+ and D- pins of the usb
5612 block/early-lookup.c for details.
5637 rw [KNL] Mount root device read-write on boot
5674 signals(usually 32 ms but configurable). Setting
5678 i.e. with the default pelt decay period of 32 ms
5680 1 64 ms
5681 2 128 ms
5689 to 10 seconds for built-in smp_call_function()
5696 that requesting even small non-zero numbers of
5703 The default of -1 specifies a number of kthreads
5708 test before initiating CPU-hotplug operations.
5712 CPU-hotplug operations. Specifying zero (which
5713 is the default) disables CPU-hotplug operations.
5719 Non-zero values are useful for automated tests.
5742 "wait" parameter. A value of -1 selects the
5743 default if all other weights are -1. However,
5745 value of -1 will instead select a weight of zero.
5750 non-zero "wait" parameter. See weight_single.
5763 non-zero "wait" parameter. See weight_single
5775 non-zero "wait" parameter. See weight_single
5782 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
5783 1 -- enable.
5794 0 -- disable.
5795 1 -- enable.
5798 serialnumber [BUGS=X86-32]
5800 sev=option[,option...] [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
5808 to set it to "all" by meaning -- no limit here.
5814 simeth= [IA-64]
5889 using the csdlock_debug- kernel parameter.
5894 system. By default, let CSD-lock acquisition
5896 for this value provides a 5-minute timeout.
5898 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
5899 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
5900 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
5901 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
5902 smsc-ircc2.ircc_irq= [HW] IRQ line
5903 smsc-ircc2.ircc_dma= [HW] DMA channel
5904 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
5914 Default: -1 (no limit)
5917 [KNL] Should the soft-lockup detector generate panics.
5920 A value of 1 instructs the soft-lockup detector
5921 to panic the machine when a soft-lockup occurs. It is
5924 respective build-time switch to that functionality.
5927 [KNL] Should the soft-lockup detector generate
5932 See Documentation/admin-guide/laptops/sonypi.rst
5939 on - (default) Enable the HW or SW mitigation
5941 off - Disable the mitigation.
5948 on - unconditionally enable, implies
5950 off - unconditionally disable, implies
5952 auto - kernel detects whether your CPU model is
5969 retpoline - replace indirect branches
5970 retpoline,generic - Retpolines
5971 retpoline,lfence - LFENCE; indirect branch
5972 retpoline,amd - alias for retpoline,lfence
5973 eibrs - Enhanced/Auto IBRS
5974 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
5975 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
5976 ibrs - use IBRS to protect kernel
5986 on - Unconditionally enable mitigations. Is
5989 off - Unconditionally disable mitigations. Is
5992 prctl - Indirect branch speculation is enabled,
5998 - Like "prctl" above, but only STIBP is
6004 - Same as "prctl" above, but all seccomp
6009 - Like "seccomp" above, but only STIBP is
6014 auto - Kernel selects the mitigation depending on
6025 off - Disable mitigation
6026 microcode - Enable microcode mitigation only
6027 safe-ret - Enable sw-only safe RET mitigation (default)
6028 ibpb - Enable mitigation by issuing IBPB on
6030 ibpb-vmexit - Issue IBPB only on VMEXIT
6031 (cloud-specific mitigation)
6056 on - Unconditionally disable Speculative Store Bypass
6057 off - Unconditionally enable Speculative Store Bypass
6058 auto - Kernel detects whether the CPU model contains an
6064 prctl - Control Speculative Store Bypass per thread
6068 seccomp - Same as "prctl" above, but all seccomp threads
6076 on,auto - On Power8 and Power9 insert a store-forwarding
6080 off - No action.
6099 off - not enabled
6101 warn - the kernel will emit rate-limited warnings
6103 exception or the #DB exception. This mode is
6109 fatal - the kernel will send SIGBUS to applications
6110 that trigger the #AC exception or the #DB
6114 ratelimit:N -
6127 #DB exception for bus lock is triggered only when
6134 Certain CPUs are vulnerable to an MDS-like
6154 This kernel-boot parameter defaults to 128,
6155 but takes effect only when the low-order four
6172 instead of the compile-time CONFIG_NR_CPUS.
6176 grace-period sequence counter wrap for the
6177 srcu_data structure's ->srcu_gp_seq_needed field.
6192 Specifies the number of no-delay instances
6199 Specifies the per-grace-period phase, number of
6200 non-sleeping polls of readers. Beyond this limit,
6206 Specifies number of microseconds of non-sleeping
6207 delay between each non-sleeping poll of readers.
6210 Specifies the number of update-side contention
6215 set for contention-based conversions to occur.
6225 force-on: Unconditionally enable mitigation for
6227 force-off: Unconditionally disable mitigation for
6250 stacktrace_filter=[function-list]
6252 will trace at boot up. function-list is a comma-separated
6260 Set the STI (builtin display/keyboard on the HP-PARISC
6262 as the initial boot-console.
6322 to global on non-NUMA machines)
6345 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
6347 <int> -- Number of I/O TLB slabs
6348 <int> -- Second integer after comma. Number of swiotlb
6351 force -- force using of bounce buffers even if they
6353 noforce -- Never use bounce buffers (for debugging)
6368 Ignore sysrq setting - this boot parameter will
6376 cache size. See Documentation/networking/ip-sysctl.rst
6383 Specify "mem" (for Suspend-to-RAM) or "standby" (for
6388 wakeup-capable RTC alarm.
6394 -1: disable all active trip points in all thermal zones
6398 -1: disable all critical trip points in all thermal zones
6405 -1: disable all passive trip points
6411 <deci-seconds>: poll all this frequency
6433 Prevent the CPU-hotplug component of torturing
6437 Dump the ftrace buffer at torture-test shutdown,
6441 with rotating-rust storage.
6446 disables verbose-printk() sleeping.
6449 Duration of each verbose-printk() sleep in jiffies.
6467 https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
6471 tracing ring buffer. This is useful for early boot up
6505 local - Use the per CPU time stamp counter
6509 global - Event time stamps are synchronize across
6512 counter - Simple counting of events (1, 2, ..)
6516 uptime - Use jiffies as the time stamp.
6517 perf - Use the same clock that perf uses.
6518 mono - Use ktime_get_mono_fast_ns() for time stamps.
6519 mono_raw - Use ktime_get_raw_fast_ns() for time
6521 boot - Use ktime_get_boot_fast_ns() for time stamps.
6525 trace_event=[event-list]
6527 to facilitate early boot debugging. The event-list is a
6528 comma-separated list of trace events to enable. See
6531 trace_instance=[instance-info]
6532 [FTRACE] Create a ring buffer instance early in boot up.
6551 trace_options=[option-list]
6553 The option-list is a comma delimited list of options
6567 trace_trigger=[trigger-list]
6604 See Documentation/admin-guide/mm/transhuge.rst
6612 - "tpm"
6613 - "tee"
6614 - "caam"
6624 - "kernel"
6625 - the same value as trusted.source: "tpm" or "tee"
6626 - "default"
6635 high-resolution timer mode on older hardware, and in
6671 on - Enable TSX on the system. Although there are
6674 several previous speculation-related CVEs, and
6678 off - Disable TSX on the system. (Note that this
6686 auto - Disable TSX if X86_BUG_TAA is present,
6691 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
6697 Similar to Micro-architectural Data Sampling (MDS)
6712 full - Enable TAA mitigation on vulnerable CPUs
6715 full,nosmt - Enable TAA mitigation and disable SMT on
6718 vulnerable to cross-thread TAA attacks.
6719 off - Unconditionally disable TAA mitigation
6721 On MDS-affected machines, tsx_async_abort=off can be
6733 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
6739 See also Documentation/input/devices/joystick-parport.rst
6741 udbg-immortal [PPC] When debugging early kernel crashes that
6747 Set number of hash buckets for UDP/UDP-Lite connections
6749 uhci-hcd.ignore_oc=
6751 Some badly-designed motherboards generate lots of
6760 unwind_debug [X86-64]
6768 (default -1 = authorized (same as 1),
6774 for newly-detected USB devices (default 2). This
6802 [USB] Specifies timeout for the initial 64-byte
6809 [USB] A list of quirk entries to augment the built-in
6812 VendorID:ProductID:Flags. The IDs are 4-digit hex
6814 will change the built-in quirk; setting it if it is
6819 a 255-byte read);
6823 Set-Interface requests);
6842 (bInterval-1).
6868 request from 5000 ms to 500 ms);
6880 usb-storage.delay_use=
6884 usb-storage.quirks=
6886 override the built-in unusual_devs list. List
6889 and Product ID values (4-digit hex numbers) and
6891 to a common usb-storage quirk flag as follows:
6933 medium is write-protected).
6942 1 - undefined instruction events
6943 2 - system calls
6944 4 - invalid data aborts
6945 8 - SIGSEGV faults
6946 16 - SIGBUS faults
6962 vdso32= [X86] Control the 32-bit vDSO
6963 vdso32=1: enable 32-bit VDSO
6964 vdso32=0 or vdso32=2: disable 32-bit VDSO
6974 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
6976 vector= [IA-64,SMP]
7008 vga= [BOOT,X86-32] Select a particular video mode
7010 Documentation/admin-guide/svga.rst.
7025 - Disable all of the above options
7046 vsyscall= [X86-64]
7049 code). Most statically-linked binaries and older
7073 see VGA-softcursor.txt. Default: 2 = underline.
7078 This is a 16-member array composed of values
7079 ranging from 0-255.
7084 This is a 16-member array composed of values
7085 ranging from 0-255.
7090 This is a 16-member array composed of values
7091 ranging from 0-255.
7096 Set system-wide default UTF-8 mode for all tty's.
7097 Default is 1, i.e. UTF-8 mode is enabled for all
7102 Format=<-1|0|1>
7103 Set system-wide default for whether a cursor
7104 is shown on new VTs. Default is -1,
7109 vt.italic= [VT] Default color for italic text; 0-15.
7112 vt.underline= [VT] Default color for underlined text; 0-15.
7116 see Documentation/watchdog/watchdog-parameters.rst
7117 or other driver-specific files in the
7131 Format: <cpu-list>
7145 Per-cpu work items which run for longer than this
7148 them from noticeably delaying other per-cpu work
7149 items. Default is 10000 (10ms).
7157 Per-cpu workqueues are generally preferred because
7159 locality; unfortunately, per-cpu workqueues tend to
7162 Enabling this makes the per-cpu workqueues which
7176 Documentation/core-api/workqueue.rst.
7189 forces round-robin CPU selection to flush out
7197 on - Enable writecombine, use WUC for ioremap_wc()
7198 off - Disable writecombine, use SUC for ioremap_wc()
7200 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
7204 xen_512gb_limit [KNL,X86-64,XEN]
7214 ide-disks -- unplug primary master IDE devices
7215 aux-ide-disks -- unplug non-primary-master IDE devices
7216 nics -- unplug network devices
7217 all -- unplug all emulated devices (NICs and IDE disks)
7218 unnecessary -- unplugging emulated devices is
7221 never -- do not unplug even if version check succeeds
7229 Select whether to always use non-faulting (safe) MSR
7254 xen_timer_slop= [X86-64,XEN]
7279 preferred over the 2-level event handling, as it is
7296 xive.store-eoi=off [PPC]
7302 xhci-hcd.quirks [USB,KNL]