Lines Matching +full:cpu +full:- +full:capacity
5 force -- enable ACPI if default was off
6 on -- enable ACPI but allow fallback to DT [arm64]
7 off -- disable ACPI if default was on
8 noirq -- do not use ACPI for IRQ routing
9 strict -- Be less tolerant of platforms that are not
11 rsdt -- prefer RSDT over (default) XSDT
12 copy_dsdt -- copy DSDT to memory
26 If set to vendor, prefer vendor-specific driver
58 Documentation/firmware-guide/acpi/debug.rst for more information about
121 Disable auto-serialization of AML methods
124 auto-serialization feature.
142 Ignore the ACPI-based watchdog interface (WDAT) and let
163 acpi_osi=! # disable all built-in OS vendor
165 acpi_osi=!! # enable all built-in OS vendor
227 For broken nForce2 BIOS resulting in XT-PIC timer.
235 as soon as the kernel's real-mode entry point is called.
265 See Documentation/sound/alsa-configuration.rst
272 align_va_addr= [X86-64]
277 CPU-intensive style benchmark, and it can vary highly in
280 32: only for 32-bit processes
281 64: only for 64-bit processes
282 on: enable for both 32- and 64-bit processes
283 off: disable for both 32- and 64-bit processes
299 Allow execve() of 32-bit applications and setting of the
301 subset of the CPUs support 32-bit EL0. When this
302 parameter is present, the set of CPUs supporting 32-bit
303 EL0 is indicated by /sys/devices/system/cpu/aarch32_el0
304 and hot-unplug operations may be restricted.
306 amd_iommu= [HW,X86-64]
309 fullflush - enable flushing of IO/TLB entries when
313 off - do not initialize any AMD IOMMU found in
315 force_isolation - Force device isolation for all
321 amd_iommu_dump= [HW,X86-64]
327 amd_iommu_intr= [HW,X86-64]
330 legacy - Use legacy interrupt remapping mode.
331 vapic - Use virtual APIC mode, which allows IOMMU
333 This mode requires kvm-amd.avic=1.
347 Power management functions (SPARCstation-4/5 + deriv.)
349 Disable APC CPU standby support. SPARCstation-Fox does
350 not play well with APC CPU idle - disable it if you have
357 when initialising the APIC and IO-APIC components.
358 For X86-32, this can also be used to specify an APIC
365 bsp: External NMI is delivered only to CPU 0
367 backup of CPU 0
378 to set it to "all" by meaning -- no limit here.
387 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
420 audit= [KNL] Enable the audit sub-system
422 0 | off - kernel audit is disabled and can not be
424 unset - kernel audit is initialized but disabled and
426 1 | on - kernel audit is initialized and partially
439 0 - Disable the BAU.
440 1 - Enable the BAU.
441 unset - Disable the BAU.
462 See Documentation/block/cmdline-partition.rst
473 See Documentation/admin-guide/bootconfig.rst
484 bttv.pll= See Documentation/admin-guide/media/bttv.rst
493 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
494 Sometimes CPU hardware bugs make them report the cache
512 inclusive. See arch/mips/include/asm/pgtable-bits.h
522 - foo isn't auto-mounted if you mount all cgroups in
524 - foo isn't visible as an individually mountable
526 - if foo is an optional feature then the feature is
532 Specifying "pressure" disables per-cgroup pressure
546 nosocket -- Disable socket memory accounting.
547 nokmem -- Disable kernel memory accounting.
552 0 -- check protection applied by kernel (includes
554 1 -- check protection requested by application.
568 force such clocks to be always-on nor does it reserve
572 information, see Documentation/driver-api/clk.rst.
574 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
591 [X86-32] pit,hpet,tsc;
598 [X86-64] hpet,tsc
604 architected timer so that code using WFE-based polling
627 cma=nn[MG]@[start[MG][-end[MG]]]
638 Sets the size of kernel per-numa memory area for
640 per-numa CMA altogether. And If this option is not
642 With per-numa CMA enabled, DMA users on node nid will
658 com20020= [HW,NET] ARCnet - COM20020 chipset
662 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
666 ARCnet - COM90xx chipset (memory-mapped buffers)
684 See Documentation/admin-guide/serial-console.rst for more
694 Start an early, polled-mode console on the 8250/16550
697 MMIO inter-register address stride is either 8-bit
698 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
702 the h/w is not re-initialized.
723 syscall, or to executing "dmesg -S --raw" or to reading
738 Enable/disable the CPU sampling based debugging.
743 disable the cpuidle sub-system
749 disable the cpufreq sub-system
757 [X86] Delay for N microsec between assert and de-assert
759 on every CPU online, such as boot, and resume from suspend.
772 [KNL, X86-64] Select a region under 4G first, and
775 See Documentation/admin-guide/kdump/kdump.rst for further details.
780 start-[end] where start and end are both
782 Documentation/admin-guide/kdump/kdump.rst for an example.
785 [KNL, X86-64] range could be above 4G. Allow kernel
792 [KNL, X86-64] range under 4G. When crashkernel=X,high
797 low memory is needed to make sure DMA buffers for 32-bit
807 [KNL] Disable crypto self-tests
821 See also Documentation/input/devices/joystick-parport.rst
825 Documentation/admin-guide/dynamic-debug-howto.rst for
839 [KNL] verbose self-tests
842 self-tests.
844 1 will print _a lot_ more information - normally
862 driver code when a CPU writes to (or reads from) a
866 memory is written at bus level and the CPU MMU is
882 Format: { on, no-mount, off }
884 no-mount:
889 get a -EPERM as result when trying to register files
893 Default value is set in build-time with a kernel configuration.
905 Documentation/admin-guide/mm/hugetlbpage.rst.
956 against bounds-checking flaws in the kernel's
975 corresponding CPU to be disabled at boot,
1016 entries for DMA-API debugging code. One entry is
1017 required per DMA-API allocation. Use this if the
1018 DMA-API debugging code disables itself because the
1022 With this option the DMA-API debugging driver
1037 Generic built-in EDID data sets are used, if one of
1042 available in Documentation/admin-guide/edid.rst. An EDID
1054 Control how the dt_cpu_ftrs device-tree binding is
1055 used for CPU feature discovery and setup (if it
1057 off: Do not use it, fall back to legacy cpu table.
1064 what data is available or for reverse-engineering.
1069 Documentation/admin-guide/dynamic-debug-howto.rst
1072 nopku [X86] Disable Memory Protection Keys CPU feature found
1086 determined by stdout-path property in device tree's
1091 Start an early, polled-mode console on a Cadence
1102 Start an early, polled-mode console on the 8250/16550
1104 MMIO inter-register address stride is either 8-bit
1105 (mmio) or 32-bit (mmio32 or mmio32be).
1113 Start an early, polled-mode console on a pl011 serial
1117 the driver will use only 32-bit accessors to read/write
1121 Start an early, polled-mode console on a meson serial
1127 Start an early, polled-mode console on an msm serial
1133 Start an early, polled-mode console on an msm serial
1139 Start an early, polled-mode console on a serial port
1145 Start an early, polled-mode console on a serial port
1151 Use RISC-V SBI (Supervisor Binary Interface) for early
1169 Start an early, polled-mode console on a lantiq serial
1183 Start an early, polled-mode, output-only console on the
1188 Start an early, polled-mode console on the
1194 Start an early, polled-mode console on a Qualcomm
1202 coherent non-x86 systems that use system memory for
1313 attribute is added to range 0x100000000-0x180000000 and
1314 0x10a0000000-0x1120000000.
1318 range 0x240000000-0x43fffffff.
1330 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1336 elanfreq= [X86-32]
1338 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1344 See Documentation/admin-guide/kdump/kdump.rst for details.
1360 0 -- permissive (log only, no denials).
1361 1 -- enforcing (deny and log).
1385 See also Documentation/fault-injection/.
1389 See Documentation/admin-guide/sysctl/net.rst for
1393 See Documentation/admin-guide/blockdev/floppy.rst.
1396 [IA-64] Avoid check_sal_cache_flush which may hang on
1401 forcepae [X86-32]
1417 dump only the buffer of the CPU that triggered the
1420 ftrace_filter=[function-list]
1422 tracer at boot up. function-list is a comma separated
1427 ftrace_notrace=[function-list]
1429 function-list. This list can be changed at run time
1433 ftrace_graph_filter=[function-list]
1436 function-list is a comma separated list of functions
1440 ftrace_graph_notrace=[function-list]
1442 function-list. This list is a comma separated list of
1462 off -- Don't create device links from firmware info.
1463 permissive -- Create device links from firmware info
1466 on -- Create device links from firmware info and use it
1468 rpm -- Like "on", but also use to order runtime PM.
1479 See also Documentation/input/devices/joystick-parport.rst
1483 gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
1507 gcov_persist= [GCOV] When non-zero (default), profiling data for
1540 gpio-mockup.gpio_mockup_ranges
1545 [KNL] Should the hard-lockup detector generate
1551 for 64-bit NUMA, off otherwise.
1554 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1561 corresponding firmware-first mode error processing
1575 hpet= [X86-32,HPET] option to control HPET usage
1592 boot-time allocation of gigantic hugepages is skipped.
1600 Documentation/admin-guide/mm/hugetlbpage.rst.
1610 Documentation/admin-guide/mm/hugetlbpage.rst.
1619 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1625 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1652 (disabled by default, and as a pre-condition
1654 i8042.direct [HW] Put keyboard port into non-translated mode
1668 suspend-to-ram transitions, only during s2r
1703 -1 -- never invert brightness
1704 0 -- machine default
1705 1 -- force brightness inversion
1710 ide-core.nodma= [HW] (E)IDE subsystem
1716 ide-generic.probe-mask= [HW] (E)IDE subsystem
1728 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1734 improve the performance of waking up a idle CPU, but
1737 idle=halt: Halt is forced to be used for CPU idle.
1739 idle=nomwait: Disable mwait for CPU C-states
1756 legacy only accept legacy-NaN binaries, if supported
1758 2008 only accept 2008-NaN binaries, if supported
1767 'relaxed' straps the emulator for both legacy-NaN and
1768 2008-NaN, whereas 'strict' enables legacy-NaN only on
1777 Ignore loglevel setting - this will print /all/
1841 Formats: { "ima" | "ima-ng" | "ima-sig" }
1842 Default: "ima-ng"
1874 initcall_blacklist= [KNL] Do not execute a comma-separated list of
1875 initcall functions. Useful for debugging built-in
1908 0 -- basic integrity auditing messages. (Default)
1909 1 -- additional integrity auditing messages.
1922 forcedac [X86-64]
1924 for io virtual address below 32-bit forcing dual
1926 than 32-bit addressing. The default is to look
1927 for translation below 32-bit and if not available
1945 could harm performance of some high-throughput
1959 1 to 9 specify maximum depth of C-state.
1969 used along with the hardware-managed P-states (HWP)
1973 in favor of acpi-cpufreq. Forcing the intel_pstate driver
1974 instead of acpi-cpufreq may disable platform features, such
1976 P-States information being indicated to OSPM and therefore
1979 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
1992 Allow per-logical-CPU P-State performance control limits using
1995 intremap= [X86-64, Intel-IOMMU]
2000 BIOS x2APIC opt-out request will be ignored
2024 0 - Lazy mode.
2030 1 - Strict mode (default).
2037 0 - Use IOMMU translation for DMA.
2038 1 - Bypass the IOMMU for DMA.
2039 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2041 io7= [HW] IO7 for Marvel-based Alpha systems
2056 See Documentation/admin-guide/nfs/nfsroot.rst.
2062 The argument is a cpu list, as described above.
2080 Enables support for pseudo-NMIs in the kernel. This
2099 [Deprecated - use cpusets instead]
2100 Format: [flag-list,]<cpu-list>
2121 is irreversible: it's not possible to bring back a CPU to
2128 You can move a process onto or off an "isolated" CPU via
2129 the CPU affinity syscalls or cpuset.
2130 <cpu number> begins at 0 and the maximum value is
2131 "number of CPUs in system - 1".
2145 interrupts are directed to the housekeeping CPU
2146 so that IO submitted on the housekeeping CPU
2147 cannot disturb the isolated CPU.
2157 The format of <cpu-list> is described above.
2161 ivrs_ioapic [HW,X86-64]
2162 Provide an override to the IOAPIC-ID<->DEVICE-ID
2166 For example, to map IOAPIC-ID decimal 10 to
2172 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2175 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2179 ivrs_hpet [HW,X86-64]
2180 Provide an override to the HPET-ID<->DEVICE-ID
2184 For example, to map HPET-ID decimal 10 to
2190 * To map HPET-ID decimal 0 to PCI device 00:14.0
2193 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2197 ivrs_acpihid [HW,X86-64]
2198 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2202 For example, to map UART-HID:UID AMD0020:0 to
2208 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2211 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2231 kernelcore= [KNL,X86,IA-64,PPC]
2234 the kernel for non-movable allocations. The requested
2244 subsystem. Note that allocations like PTEs-from-HighMem
2252 for non-movable allocations and remaining memory is used
2263 gdb or control-c on the dbgp connection. When
2264 not using this parameter you use sysrq-g to break into
2269 or a supported polling keyboard driver (non-usb).
2296 Configure the RouterBoard 532 series on-chip
2299 kmemleak= [KNL] Boot-time kmemleak enable/disable
2305 kprobe_event=[probe-list]
2307 The probe-list is a semicolon delimited list of probe
2353 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
2356 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
2358 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
2360 kvm-arm.mode=
2365 nvhe: Standard nVHE-based mode, without support for
2368 protected: nVHE-based mode with support for guests whose
2375 kvm-arm.vgic_v3_group0_trap=
2376 [KVM,ARM] Trap guest accesses to GICv3 group-0
2379 kvm-arm.vgic_v3_group1_trap=
2380 [KVM,ARM] Trap guest accesses to GICv3 group-1
2383 kvm-arm.vgic_v3_common_trap=
2387 kvm-arm.vgic_v4_enable=
2399 kvm-intel.ept= [KVM,Intel] Disable extended page tables
2403 kvm-intel.emulate_invalid_guest_state=
2405 Ignored if kvm-intel.enable_unrestricted_guest=1, as
2411 kvm-intel.flexpriority=
2415 kvm-intel.nested=
2419 kvm-intel.unrestricted_guest=
2424 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2425 CVE-2018-3620.
2436 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
2503 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2509 lapic [X86-32,APIC] Enable the local APIC even if BIOS
2513 value for LAPIC timer one-shot implementation. Default
2548 first fan-out link behind PMP device. It does not
2562 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2574 hot-unplug link recovery
2589 call memblock_remove on the regions marked with no-map
2617 Set the number of locking read-acquisition kthreads.
2622 Set the number of locking write-acquisition kthreads.
2625 Set time (s) after boot for CPU-hotplug testing.
2628 Set time (s) between CPU-hotplug operations, or
2629 zero to disable CPU-hotplug testing.
2632 Set task-shuffle interval (jiffies). Shuffling
2633 tasks allows some CPUs to go into dyntick-idle
2638 is useful for hands-off automated testing.
2671 7 (KERN_DEBUG) debug-level messages
2681 logo.nologo [FB] Disables display of the built-in Linux logo.
2699 an IEEE 1284-compliant printer is attached; if
2705 time-consuming boot-time autodetection (up to 250 ms per
2706 CPU). 0 enables autodetection (default). To determine
2726 machvec= [IA-64] Force the use of a particular machine-vector
2732 Example: machtype=lemote-yeeloong-2f-7inch
2740 bootup you can bring up the other plugged cpu by executing
2741 "echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus
2747 (loop.max_loop) unconditionally pre-created at init time. The default
2750 devices can be requested on-demand with the
2751 /dev/loop-control interface.
2753 mce [X86-32] Machine Check Exception
2755 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.rst
2758 See Documentation/admin-guide/md.rst.
2765 Control mitigation for the Micro-architectural Data
2768 Certain CPUs are vulnerable to an exploit against CPU
2780 full - Enable MDS mitigation on vulnerable CPUs
2781 full,nosmt - Enable MDS mitigation and disable
2783 off - Unconditionally disable MDS mitigation
2785 On TAA-affected machines, mds=off can be prevented by
2794 For details see: Documentation/admin-guide/hw-vuln/mds.rst
2813 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
2818 per-device physically contiguous DMA buffers.
2826 See Documentation/admin-guide/mm/memory-hotplug.rst.
2851 Example: Exclude memory from 0x18690000-0x1869ffff
2865 memmap=<size>%<offset>-<oldtype>+<newtype>
2867 from <oldtype> to <newtype>. If "-<oldtype>" is left
2882 repeatable BIOS-originated corruption always
2907 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
2915 Refer to Documentation/virt/kvm/amd-memory-encryption.rst
2919 s2idle - Suspend-To-Idle
2920 shallow - Power-On Suspend or equivalent (if supported)
2921 deep - Suspend-To-RAM or equivalent (if supported)
2922 See Documentation/admin-guide/pm/sleep-states.rst.
2925 See Documentation/admin-guide/media/meye.rst.
2927 mfgpt_irq= [IA-32] Specify the IRQ to use for the
2928 Multi-Function General Purpose Timers on AMD Geode
2931 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
2945 0 - The attached screen is the 3.5" TFT
2946 1 - The attached screen is the 7" TFT
2947 2 - The VGA Shield is attached (1024x768)
2951 b - Enable backlight. The TFT backlight pin will be
2955 c - Enable the s3c camera interface.
2956 t - Reserved for enabling touchscreen support. The
2960 https://repo.or.cz/w/linux-2.6/mini2440.git
2964 CPU vulnerabilities. This is a set of curated,
2965 arch-independent options, each of which is an
2966 aggregation of existing arch-specific options.
2969 Disable all optional CPU mitigations. This
2971 expose users to several CPU vulnerabilities.
2987 ssbd=force-off [ARM64]
2996 Mitigate all CPU vulnerabilities, but leave SMT
3000 have other ways of avoiding SMT-based attacks.
3004 Mitigate all CPU vulnerabilities, disabling SMT
3028 the same CPU buffers as affected by MDS and TAA.
3030 is to clear the affected CPU buffers.
3035 full - Enable mitigation on vulnerable CPUs
3037 full,nosmt - Enable mitigation and disable SMT on
3040 off - Unconditionally disable mitigation
3053 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3061 module_blacklist= [KNL] Do not load a comma-separated list of
3075 movablecore= [KNL,X86,IA-64,PPC]
3086 movable_node [KNL] Boot-time switch to make hotplugable memory
3093 Format: <name>,<region-number>,<size>,<offset>
3096 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3108 CPU resources toward proactive page replacement with the goal of
3109 reducing direct reclaims. When direct reclaims are prevented, the CPU
3111 result can cause aggregate CPU usage on the system to go up, down or
3119 The range of acceptible values are 1-16. Always start with lower
3120 values in the 2-6 range. Higher values should be justified with
3125 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
3129 boundary - index of last SLC block on Flex-OneNAND.
3131 lock - Configure if Flex-OneNAND boundary should be locked.
3138 See arch/arm/mach-s3c2412/mach-jive.c
3166 something different and driver-specific.
3177 See Documentation/admin-guide/nfs/nfsroot.rst.
3179 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3180 See Documentation/admin-guide/nfs/nfsroot.rst.
3183 See Documentation/admin-guide/nfs/nfsroot.rst.
3207 [NFS] enable 64-bit inode numbers.
3208 If zero, the NFS client will fake up a 32-bit inode
3210 of returning the full 64-bit number.
3211 The default is to return 64-bit inode numbers.
3241 [NFS4] Specify an additional fixed unique ident-
3272 driver. A non-zero value sets the minimum interval
3284 NMI stack-backtrace request.
3293 0 - turn hardlockup detector in nmi_watchdog off
3294 1 - turn hardlockup detector in nmi_watchdog on
3311 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3315 no5lvl [X86-64] Disable 5-level paging mode. Forces
3316 kernel to use 4-level paging instead.
3347 caches in the slab allocator. Saves per-node memory,
3353 (CPU alternatives feature).
3367 nodelayacct [KNL] Disable per-task delay accounting
3373 no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel.
3375 noexec [IA-64]
3378 On X86-32 available only on PAE configured kernels.
3379 noexec=on: enable non-executable mappings (default)
3380 noexec=off: disable non-executable mappings
3390 noexec32 [X86-64]
3391 This affects only 32-bit executables.
3392 noexec32=on: enable non-executable mappings (default)
3394 noexec32=off: disable non-executable mappings
3399 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3401 legacy floating-point registers on task switch.
3425 [PPC] Don't flush the L1-D cache after accessing user data.
3429 enabling legacy floating-point and sse state.
3454 nohalt [IA-64] Tells the kernel not to use the power saving
3456 power-consumption. On the positive side, it reduces
3457 interrupt wake-up latency, which may improve performance
3459 real-time systems.
3469 compared. However, if this command-line option is
3482 The argument is a cpu list, as described above.
3485 whenever possible. The boot CPU will be forced outside
3493 noirqdebug [X86-32] Disables the code which attempts to detect and
3504 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
3506 [Deprecated - use intremap=off]
3508 nointroute [IA-64]
3510 noinvpcid [X86] Disable the INVPCID cpu feature.
3512 nojitter [IA-64] Disables jitter checking for ITC timers.
3514 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
3516 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
3519 no-vmw-sched-clock
3523 no-steal-acc [X86,PV_OPS,ARM64] Disable paravirtualized steal time
3527 nolapic [X86-32,APIC] Do not enable or use the local APIC.
3529 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
3534 nomca [IA-64] Disable machine check abort handling
3536 nomce [X86-32] Disable Machine Check Exception
3538 nomfgpt [X86-32] Disable Multi-Function General Purpose
3550 nopcid [X86-64] Disable the PCID cpu feature.
3555 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
3566 no-scroll [VGA] Disables scrollback.
3567 This is required for the Braillex ib80-piezo Braille
3570 nosbagart [IA-64]
3572 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
3577 nosoftlockup [KNL] Disable the soft-lockup detector.
3582 soft-lockup and NMI watchdog (hard-lockup).
3586 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
3611 nptcg= [IA-64] Override max number of concurrent global TLB
3618 number of already plugged CPU during bootup, later in
3619 runtime you can physically add extra cpu until it reaches
3620 n. So during boot up some boot time memory for per-cpu
3621 variables need be pre-allocated for later physical cpu
3632 See Documentation/admin-guide/sysctl/vm.rst for details.
3635 See Documentation/core-api/debugging-via-ohci1394.rst for more
3653 oprofile.cpu_type= Force an oprofile cpu type
3659 CPU specific event set.
3674 running on a platform with a direct-mapped memory-side
3680 page_owner= [KNL] Boot-time page_owner enabling option.
3686 page_poison= [KNL] Boot-time parameter changing the state of
3716 See Documentation/admin-guide/tainted-kernels.rst for
3723 pelt= [KNL] Boot-time parameter changing the PELT half life in ms
3730 Run kdump after running panic-notifiers and dumping
3775 See also Documentation/admin-guide/blockdev/paride.rst.
3804 bios [X86-32] force use of PCI BIOS, don't access
3806 has a non-standard PCI host bridge.
3807 nobios [X86-32] disallow use of PCI BIOS, only direct
3813 data in IO port 0xCFC, both 32-bit).
3815 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
3816 the function, IO port 0xCFA, also 8-bit, sets
3818 through ports 0xC000-0xCFFF).
3825 root domains (aka PCI segments, in ACPI-speak).
3830 config space on AMD family 10h CPU
3833 disable the use of MSI interrupts system-wide.
3838 primary IO-APIC for bridges that cannot disable
3845 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
3869 F0000h-100000h range.
3874 assign-busses [X86] Always assign all PCI bus
3902 bfsort Sort PCI devices into breadth-first order.
3905 nobfsort Don't sort PCI devices into breadth-first order.
3907 tuning and use the BIOS-configured MPS defaults.
3917 configuration allows peer-to-peer DMA between
3920 that hot-added devices will work.
3935 A PCI-PCI bridge can be specified if resource
3941 for 4096-byte alignment.
3943 end-to-end CRC checking).
3972 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4008 dpc-native Use native PCIe service for DPC only. May
4025 Keep all power-domains already enabled by bootloader on,
4031 See Documentation/admin-guide/blockdev/paride.rst.
4046 See Documentation/admin-guide/blockdev/paride.rst.
4049 See Documentation/admin-guide/blockdev/paride.rst.
4051 pirq= [SMP,APIC] Manual mp-table setup
4052 See Documentation/x86/i386/IO-APIC.rst.
4056 See also Documentation/admin-guide/parport.rst.
4067 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4076 { on | off | curr | res | no-curr | no-res }
4101 function to NULL. On Idle the CPU just reduces
4114 print-fatal-signals=
4120 coredump - etc.
4123 you might want to try "ulimit -i unlimited".
4135 on - unlimited logging to /dev/kmsg from userspace
4136 off - logging to /dev/kmsg disabled
4137 ratelimit - ratelimit the logging
4144 Limit processor to maximum C-state
4148 Ignore the _CST method to determine C-states,
4155 Param: "schedule" - profile schedule points.
4156 Param: "sleep" - profile D-state sleeping (millisecs).
4158 Param: "kvm" - profile VM exits.
4159 Param: <number> - step/bucket size as a power of 2 for
4189 See Documentation/admin-guide/blockdev/paride.rst.
4191 pti= [X86-64] Control Page Table Isolation of user and
4196 on - unconditionally enable
4197 off - unconditionally disable
4198 auto - kernel detects whether your CPU model is
4203 nopti [X86-64]
4207 [KNL] Number of legacy pty's. Overwrites compiled-in
4215 See Documentation/admin-guide/md.rst.
4218 See Documentation/admin-guide/blockdev/ramdisk.rst.
4224 CPU's random number generator (if available) to
4234 ras=option[,option,...] [KNL] RAS-specific options
4241 The argument is a cpu list, as described above,
4243 specify every CPU on the system.
4246 the specified list of CPUs to be no-callback CPUs.
4249 purpose, where "x" is "p" for RCU-preempt, and
4250 "s" for RCU-sched, and "N" is the CPU number.
4252 which can be useful for HPC and real-time
4261 This improves the real-time response for the
4278 RCU grace-period cleanup.
4282 RCU grace-period initialization.
4286 RCU grace-period pre-initialization, that is,
4287 the propagation of recent CPU-hotplug changes up
4292 per-CPU rcuc kthreads. Defaults to a non-zero
4300 cache-to-cache transfer latencies.
4306 and for NUMA systems with large remote-access
4312 maintained per one CPU. Object size is equal
4319 Set delay from grace-period initialization to
4332 soliciting quiescent-state help from
4344 Set the SCHED_FIFO priority of the RCU per-CPU
4347 and for the RCU grace-period kthreads (rcu_bh,
4349 set, valid values are 1-99 and the default is 1
4350 (the least-favored priority). Otherwise, when
4351 RCU_BOOST is not set, valid values are 0-99 and
4352 the default is zero (non-realtime operation).
4358 the wakeup overhead on the global grace-period
4360 each group's NOCB grace-period kthread.
4368 batch limiting is re-enabled.
4372 RCU's force-quiescent-state scan will aggressively
4390 Cause the grace-period kthread to get an extra
4392 it should at force-quiescent-state time.
4398 this specifies an rcu_read_unlock()-time delay
4402 of RCU-protected pointers after the relevant
4412 grace-period primitives such as call_rcu().
4423 grace-period primitives.
4426 Set test-start holdoff period. The purpose of
4445 Set number of RCU readers. The value -1 selects
4447 "n" less than -1 selects N-n+1, where N is again
4448 the number of CPUs. For example, -2 selects N
4449 (the number of CPUs), -3 selects N+1, and so on.
4450 A value of "n" less than or equal to -N selects
4463 complete. This is useful for hands-off automated
4470 Write-side holdoff between grace periods,
4487 Enable RCU grace-period forward-progress testing
4491 Specify the fraction of a CPU-stall-warning
4492 period to do tight-loop forward-progress testing.
4496 forward-progress tests.
4500 need_resched() during tight-loop forward-progress
4504 Use conditional/asynchronous update-side
4508 Use expedited update-side primitives, if available.
4511 Use normal (non-expedited) asynchronous
4512 update-side primitives, if available.
4515 Use normal (non-expedited) synchronous
4516 update-side primitives, if available. If all
4520 they are all non-zero.
4528 Leak an RCU-protected pointer out of the reader.
4543 Set number of RCU readers. The value -1 selects
4544 N-1, where N is the number of CPUs. A value
4545 "n" less than -1 selects N-n-2, where N is again
4546 the number of CPUs. For example, -2 selects N
4547 (the number of CPUs), -3 selects N+1, and so on.
4550 Enable debug-object double-call_rcu() testing.
4553 Set time (s) after boot for CPU-hotplug testing.
4556 Set time (jiffies) between CPU-hotplug operations,
4557 or zero to disable CPU-hotplug testing.
4560 Set the number of read-then-exit kthreads used
4562 task-exit processing.
4565 The number of times in a given read-then-exit
4566 episode that a set of read-then-exit kthreads
4571 read-then-exit testing episodes.
4574 Set task-shuffle interval (s). Shuffling tasks
4575 allows some CPUs to go into dyntick-idle mode
4580 is useful for hands-off automated testing.
4583 Duration of CPU stall (s) to test RCU CPU stall
4589 to any other stall-related activity.
4599 grace-period kthread to test RCU CPU stall
4602 kthread is starved first, then the CPU.
4625 Test RCU's dyntick-idle handling. See also the
4635 Dump ftrace buffer after reporting RCU CPU
4639 Suppress RCU CPU stall warning messages.
4642 Suppress RCU CPU stall warning messages and
4648 Set timeout for RCU CPU stall warning messages.
4651 Use expedited grace-period primitives, for
4654 but can increase CPU utilization, degrade
4655 real-time latency, and degrade energy efficiency.
4659 Use only normal grace-period primitives,
4662 real-time latency, CPU utilization, and
4664 increased grace-period latency. This parameter
4671 only normal grace-period primitives. No effect
4678 number avoids disturbing real-time workloads,
4695 force - Override the decision by the kernel to hide the
4723 Set test-start holdoff period. The purpose of
4732 but the default has already reduced the per-pass
4737 Set number of readers. The default value of -1
4746 Set the read-side critical-section duration,
4750 Specify the read-protection implementation to test.
4763 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
4771 reservetop= [X86-32]
4793 See Documentation/power/swsusp-and-swap-files.rst
4809 during restoration read-only).
4817 AMD-based UNRET and IBPB mitigations alone do not stop
4819 sibling threads. For that reason, STIBP is used on pro-
4823 off - no mitigation
4824 auto - automatically select a migitation
4825 auto,nosmt - automatically select a mitigation,
4829 ibpb - On AMD, mitigate short speculation
4834 ibpb,nosmt - Like "ibpb" above but will disable SMT
4838 unret - Force enable untrained return thunks,
4839 only effective on AMD f15h-f17h based
4841 unret,nosmt - Like unret, but will disable SMT when STIBP
4846 time according to the CPU.
4869 ro [KNL] Mount root device read-only on boot
4872 on Mark read-only kernel memory as read-only (default).
4873 off Leave read-only kernel memory writable for debugging.
4878 debug-uart get routed to the D+ and D- pins of the usb
4900 rw [KNL] Mount root device read-write on boot
4942 to 10 seconds for built-in smp_call_function()
4949 that requesting even small non-zero numbers of
4950 seconds can result in RCU CPU stall warnings,
4956 The default of -1 specifies a number of kthreads
4961 test before initiating CPU-hotplug operations.
4965 CPU-hotplug operations. Specifying zero (which
4966 is the default) disables CPU-hotplug operations.
4972 Non-zero values are useful for automated tests.
4985 preempt_disable() to disable CPU hotplug
4995 "wait" parameter. A value of -1 selects the
4996 default if all other weights are -1. However,
4998 value of -1 will instead select a weight of zero.
5003 non-zero "wait" parameter. See weight_single.
5016 non-zero "wait" parameter. See weight_single
5028 non-zero "wait" parameter. See weight_single
5031 skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
5035 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
5036 1 -- enable.
5047 0 -- disable.
5048 1 -- enable.
5054 0 -- disable.
5055 1 -- enable.
5058 serialnumber [BUGS=X86-32]
5063 simeth= [IA-64]
5097 memory cgroup sub-caches. 1 to enable, 0 to disable.
5130 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
5131 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
5132 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
5133 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
5134 smsc-ircc2.ircc_irq= [HW] IRQ line
5135 smsc-ircc2.ircc_dma= [HW] DMA channel
5136 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
5142 CPUs) to use per physical CPU on systems capable of
5146 Default: -1 (no limit)
5149 [KNL] Should the soft-lockup detector generate panics.
5152 A value of 1 instructs the soft-lockup detector
5153 to panic the machine when a soft-lockup occurs. It is
5156 respective build-time switch to that functionality.
5159 [KNL] Should the soft-lockup detector generate
5164 See Documentation/admin-guide/laptops/sonypi.rst
5171 on - unconditionally enable, implies
5173 off - unconditionally disable, implies
5175 auto - kernel detects whether your CPU model is
5180 CPU, the available microcode, the setting of the
5192 retpoline - replace indirect branches
5193 retpoline,generic - Retpolines
5194 retpoline,lfence - LFENCE; indirect branch
5195 retpoline,amd - alias for retpoline,lfence
5196 eibrs - enhanced IBRS
5197 eibrs,retpoline - enhanced IBRS + Retpolines
5198 eibrs,lfence - enhanced IBRS + LFENCE
5199 ibrs - use IBRS to protect kernel
5209 on - Unconditionally enable mitigations. Is
5212 off - Unconditionally disable mitigations. Is
5215 prctl - Indirect branch speculation is enabled,
5221 - Like "prctl" above, but only STIBP is
5227 - Same as "prctl" above, but all seccomp
5232 - Like "seccomp" above, but only STIBP is
5237 auto - Kernel selects the mitigation depending on
5238 the available CPU features and vulnerability.
5249 off - Disable mitigation
5250 microcode - Enable microcode mitigation only
5251 safe-ret - Enable sw-only safe RET mitigation (default)
5252 ibpb - Enable mitigation by issuing IBPB on
5254 ibpb-vmexit - Issue IBPB only on VMEXIT
5255 (cloud-specific mitigation)
5280 on - Unconditionally disable Speculative Store Bypass
5281 off - Unconditionally enable Speculative Store Bypass
5282 auto - Kernel detects whether the CPU model contains an
5285 CPU is not vulnerable, "off" is selected. If the
5286 CPU is vulnerable the default mitigation is
5288 prctl - Control Speculative Store Bypass per thread
5292 seccomp - Same as "prctl" above, but all seccomp threads
5300 on,auto - On Power8 and Power9 insert a store-forwarding
5304 off - No action.
5321 off - not enabled
5323 warn - the kernel will emit rate limited warnings
5328 fatal - the kernel will send SIGBUS to applications
5340 Certain CPUs are vulnerable to an MDS-like
5358 grace-period sequence counter wrap for the
5359 srcu_data structure's ->srcu_gp_seq_needed field.
5381 force-on: Unconditionally enable mitigation for
5383 force-off: Unconditionally disable mitigation for
5406 stacktrace_filter=[function-list]
5408 will trace at boot up. function-list is a comma separated
5416 Set the STI (builtin display/keyboard on the HP-PARISC
5418 as the initial boot-console.
5457 percpu one pool for each CPU
5459 to global on non-NUMA machines)
5485 it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)
5487 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
5489 <int> -- Number of I/O TLB slabs
5490 force -- force using of bounce buffers even if they
5492 noforce -- Never use bounce buffers (for debugging)
5516 Ignore sysrq setting - this boot parameter will
5524 cache size. See Documentation/networking/ip-sysctl.rst
5530 Specify "mem" (for Suspend-to-RAM) or "standby" (for
5535 wakeup-capable RTC alarm.
5541 -1: disable all active trip points in all thermal zones
5545 -1: disable all critical trip points in all thermal zones
5556 -1: disable all passive trip points
5562 <deci-seconds>: poll all this frequency
5571 Specify if the kernel should make use of the cpu
5584 Prevent the CPU-hotplug component of torturing
5588 Dump the ftrace buffer at torture-test shutdown,
5592 with rotating-rust storage.
5606 [FTRACE] will set tracing buffer size on each cpu.
5608 trace_event=[event-list]
5610 to facilitate early boot debugging. The event-list is a
5614 trace_options=[option-list]
5616 The option-list is a comma delimited list of options
5666 See Documentation/admin-guide/mm/transhuge.rst
5674 high-resolution timer mode on older hardware, and in
5700 on - Enable TSX on the system. Although there are
5703 several previous speculation-related CVEs, and
5707 off - Disable TSX on the system. (Note that this
5715 auto - Disable TSX if X86_BUG_TAA is present,
5720 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5726 Similar to Micro-architectural Data Sampling (MDS)
5729 exploit against CPU internal buffers which can forward
5741 full - Enable TAA mitigation on vulnerable CPUs
5744 full,nosmt - Enable TAA mitigation and disable SMT on
5746 is not disabled because CPU is not
5747 vulnerable to cross-thread TAA attacks.
5748 off - Unconditionally disable TAA mitigation
5750 On MDS-affected machines, tsx_async_abort=off can be
5762 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5768 See also Documentation/input/devices/joystick-parport.rst
5770 udbg-immortal [PPC] When debugging early kernel crashes that
5776 Set number of hash buckets for UDP/UDP-Lite connections
5778 uhci-hcd.ignore_oc=
5780 Some badly-designed motherboards generate lots of
5791 (default -1 = authorized except for wireless USB,
5797 for newly-detected USB devices (default 2). This
5825 [USB] Specifies timeout for the initial 64-byte
5832 [USB] A list of quirk entries to augment the built-in
5835 VendorID:ProductID:Flags. The IDs are 4-digit hex
5837 will change the built-in quirk; setting it if it is
5842 a 255-byte read);
5846 Set-Interface requests);
5865 (bInterval-1).
5900 usb-storage.delay_use=
5904 usb-storage.quirks=
5906 override the built-in unusual_devs list. List
5909 and Product ID values (4-digit hex numbers) and
5911 to a common usb-storage quirk flag as follows:
5917 device capacity by one sector);
5927 reported device capacity by one
5941 o = CAPACITY_OK (accept the capacity
5953 medium is write-protected).
5962 1 - undefined instruction events
5963 2 - system calls
5964 4 - invalid data aborts
5965 8 - SIGSEGV faults
5966 16 - SIGBUS faults
5982 vdso32= [X86] Control the 32-bit vDSO
5983 vdso32=1: enable 32-bit VDSO
5984 vdso32=0 or vdso32=2: disable 32-bit VDSO
5994 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
5996 vector= [IA-64,SMP]
6027 vga= [BOOT,X86-32] Select a particular video mode
6029 Documentation/admin-guide/svga.rst.
6044 - Disable all of the above options
6065 vsyscall= [X86-64]
6068 code). Most statically-linked binaries and older
6092 see VGA-softcursor.txt. Default: 2 = underline.
6097 This is a 16-member array composed of values
6098 ranging from 0-255.
6103 This is a 16-member array composed of values
6104 ranging from 0-255.
6109 This is a 16-member array composed of values
6110 ranging from 0-255.
6115 Set system-wide default UTF-8 mode for all tty's.
6116 Default is 1, i.e. UTF-8 mode is enabled for all
6121 Format=<-1|0|1>
6122 Set system-wide default for whether a cursor
6123 is shown on new VTs. Default is -1,
6128 vt.italic= [VT] Default color for italic text; 0-15.
6131 vt.underline= [VT] Default color for underlined text; 0-15.
6135 see Documentation/watchdog/watchdog-parameters.rst
6136 or other driver-specific files in the
6162 that this also can be controlled per-workqueue for
6166 Per-cpu workqueues are generally preferred because
6168 locality; unfortunately, per-cpu workqueues tend to
6171 Enabling this makes the per-cpu workqueues which
6182 items queued without explicit CPU specified are put
6183 on the local CPU. This guarantee is no longer true
6184 and while local CPU is still preferred work items
6186 forces round-robin CPU selection to flush out
6191 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
6195 x86_intel_mid_timer= [X86-32,APBT]
6201 xen_512gb_limit [KNL,X86-64,XEN]
6211 ide-disks -- unplug primary master IDE devices
6212 aux-ide-disks -- unplug non-primary-master IDE devices
6213 nics -- unplug network devices
6214 all -- unplug all emulated devices (NICs and IDE disks)
6215 unnecessary -- unplugging emulated devices is
6218 never -- do not unplug even if version check succeeds
6245 xen_timer_slop= [X86-64,XEN]
6270 preferred over the 2-level event handling, as it is
6297 xhci-hcd.quirks [USB,KNL]