Lines Matching +full:can +full:- +full:disable
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
31 If set to none, disable the ACPI backlight interface.
40 Disable AML predefined validation mechanism
41 This mechanism can repair the evaluation result to make
58 Documentation/firmware-guide/acpi/debug.rst for more information about
81 can interfere with legacy drivers.
113 by unsupported hardware/firmware features can result in
116 This facility can be used to prevent such uncontrolled
121 Disable auto-serialization of AML methods
124 auto-serialization feature.
128 acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump
132 Disable installation of static SSDTs at early boot time
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
167 acpi_osi= # disable all strings
169 'acpi_osi=!' can be used in combination with single or
171 vendor string(s). Note that such command can only
182 can make '_OSI("Windows 2000")' TRUE.
186 exist in the ACPI namespace. NOTE that such command can
191 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
194 'acpi_osi=!*' can be used in combination with single or
196 string(s). Note that such command can affect the
206 1. 'acpi_osi="Module Device" acpi_osi=!*' can make
208 2. 'acpi_osi=!* acpi_osi="Module Device"' can make
227 For broken nForce2 BIOS resulting in XT-PIC timer.
235 as soon as the kernel's real-mode entry point is called.
260 off: disable AGP support
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
292 amd_iommu= [HW,X86-64]
295 fullflush - enable flushing of IO/TLB entries when
299 off - do not initialize any AMD IOMMU found in
301 force_isolation - Force device isolation for all
307 amd_iommu_dump= [HW,X86-64]
313 amd_iommu_intr= [HW,X86-64]
316 legacy - Use legacy interrupt remapping mode.
317 vapic - Use virtual APIC mode, which allows IOMMU
319 This mode requires kvm-amd.avic=1.
333 Power management functions (SPARCstation-4/5 + deriv.)
335 Disable APC CPU standby support. SPARCstation-Fox does
336 not play well with APC CPU idle - disable it if you have
343 when initialising the APIC and IO-APIC components.
344 For X86-32, this can also be used to specify an APIC
364 to set it to "all" by meaning -- no limit here.
373 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
397 audit= [KNL] Enable the audit sub-system
399 0 | off - kernel audit is disabled and can not be
401 unset - kernel audit is initialized but disabled and
403 1 | on - kernel audit is initialized and partially
414 behavior is to disable the BAU (i.e. bau=0).
416 0 - Disable the BAU.
417 1 - Enable the BAU.
418 unset - Disable the BAU.
439 See Documentation/block/cmdline-partition.rst
447 Extended command line options can be added to an initrd
450 See Documentation/admin-guide/bootconfig.rst
453 Disable BERT OS support on buggy BIOSes.
456 Disable BGRT to avoid flickering OEM logo.
461 bttv.pll= See Documentation/admin-guide/media/bttv.rst
470 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
489 inclusive. See arch/mips/include/asm/pgtable-bits.h
496 cgroup_disable= [KNL] Disable a particular controller
497 Format: {name of the controller(s) to disable}
499 - foo isn't auto-mounted if you mount all cgroups in
501 - foo isn't visible as an individually mountable
504 cut the overhead, others just disable the usage. So
507 cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1
518 nosocket -- Disable socket memory accounting.
519 nokmem -- Disable kernel memory accounting.
520 kmem -- Enable kernel memory accounting.
525 0 -- check protection applied by kernel (includes
527 1 -- check protection requested by application.
529 Value can be changed at runtime via
541 force such clocks to be always-on nor does it reserve
545 information, see Documentation/driver-api/clk.rst.
547 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
564 [X86-32] pit,hpet,tsc;
571 [X86-64] hpet,tsc
576 Enable/disable the eventstream feature of the ARM
577 architected timer so that code using WFE-based polling
578 loops can be debugged more effectively on production
588 Disable CPUID feature X for the kernel. See
597 Also note the kernel might malfunction if you disable
600 cma=nn[MG]@[start[MG][-end[MG]]]
611 Sets the size of kernel per-numa memory area for
613 per-numa CMA altogether. And If this option is not
615 With per-numa CMA enabled, DMA users on node nid will
631 com20020= [HW,NET] ARCnet - COM20020 chipset
635 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
639 ARCnet - COM90xx chipset (memory-mapped buffers)
657 See Documentation/admin-guide/serial-console.rst for more
667 Start an early, polled-mode console on the 8250/16550
670 MMIO inter-register address stride is either 8-bit
671 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
675 the h/w is not re-initialized.
696 syscall, or to executing "dmesg -S --raw" or to reading
711 Enable/disable the CPU sampling based debugging.
712 0: default value, disable debugging
716 disable the cpuidle sub-system
722 disable the cpufreq sub-system
730 [X86] Delay for N microsec between assert and de-assert
740 [KNL] Using kexec, Linux can switch to a 'crash kernel'
745 [KNL, X86-64] Select a region under 4G first, and
748 See Documentation/admin-guide/kdump/kdump.rst for further details.
753 start-[end] where start and end are both
755 Documentation/admin-guide/kdump/kdump.rst for an example.
758 [KNL, X86-64] range could be above 4G. Allow kernel
765 [KNL, X86-64] range under 4G. When crashkernel=X,high
770 low memory is needed to make sure DMA buffers for 32-bit
775 0: to disable low allocation.
780 [KNL] Disable crypto self-tests
794 See also Documentation/input/devices/joystick-parport.rst
798 Documentation/admin-guide/dynamic-debug-howto.rst for
812 [KNL] verbose self-tests
815 self-tests.
817 1 will print _a lot_ more information - normally
823 [KNL] Disable object debugging
855 Format: { on, no-mount, off }
857 no-mount:
858 Filesystem is not registered but kernel clients can
859 access APIs and a crashkernel can be used to read
862 get a -EPERM as result when trying to register files
866 Default value is set in build-time with a kernel configuration.
878 Documentation/admin-guide/mm/hugetlbpage.rst.
908 can be useful when debugging issues that require an SLB
916 disable= [IPV6]
925 against bounds-checking flaws in the kernel's
928 off Disable hardened usercopy checks.
931 Disable RADIX MMU mode on POWER9
934 Disable RADIX GTSE feature and use hcall for TLB
938 Disable TLBIE instruction. Currently does not work
946 disable BSP to wake up multiple CPUs without
952 Disable Intel PMU counter freezing feature.
957 Disable Dynamic DMA Window support. Use this
975 Disable PIN 1 of APIC timer
976 Can be useful to work around chipset bugs.
978 dis_ucode_ldr [X86] Disable the microcode loader.
985 entries for DMA-API debugging code. One entry is
986 required per DMA-API allocation. Use this if the
987 DMA-API debugging code disables itself because the
991 With this option the DMA-API debugging driver
992 filter feature can be enabled at boot time. Just
994 The filter can be disabled or changed to another
1011 are enabled. In order to disable RFDS mitigation all
1015 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
1026 Generic built-in EDID data sets are used, if one of
1031 available in Documentation/admin-guide/edid.rst. An EDID
1043 Control how the dt_cpu_ftrs device-tree binding is
1053 what data is available or for reverse-engineering.
1058 Documentation/admin-guide/dynamic-debug-howto.rst
1061 nopku [X86] Disable Memory Protection Keys CPU feature found
1075 determined by stdout-path property in device tree's
1080 Start an early, polled-mode console on a Cadence
1091 Start an early, polled-mode console on the 8250/16550
1093 MMIO inter-register address stride is either 8-bit
1094 (mmio) or 32-bit (mmio32 or mmio32be).
1102 Start an early, polled-mode console on a pl011 serial
1106 the driver will use only 32-bit accessors to read/write
1110 Start an early, polled-mode console on a meson serial
1116 Start an early, polled-mode console on an msm serial
1122 Start an early, polled-mode console on an msm serial
1128 Start an early, polled-mode console on a serial port
1134 Start an early, polled-mode console on a serial port
1140 Use RISC-V SBI (Supervisor Binary Interface) for early
1158 Start an early, polled-mode console on a lantiq serial
1172 Start an early, polled-mode, output-only console on the
1177 Start an early, polled-mode console on the
1183 Start an early, polled-mode console on a Qualcomm
1191 coherent non-x86 systems that use system memory for
1216 Append ",keep" to not disable it when the real console
1219 Only one of vga, efi, serial, or usb debug port can
1227 You can find the port for a given device in
1237 The xen output can only be used by Xen PV guests.
1239 The sclp output can only be used on s390.
1249 off: disable H/W event reporting through EDAC.
1260 but can only be used if the backing tty is available
1272 disable_early_pci_dma: disable the busmaster bit on all
1274 nochunk: disable reading files in "chunks" in the EFI
1275 boot stub, as chunking can cause problems with some
1277 noruntime : disable EFI runtime services support
1281 claim. Specify efi=nosoftreserve to disable this
1289 Using this parameter you can use more than 50% of
1302 attribute is added to range 0x100000000-0x180000000 and
1303 0x10a0000000-0x1120000000.
1307 range 0x240000000-0x43fffffff.
1309 Using this parameter you can do debugging of EFI memmap
1310 related features. For example, you can do debugging of
1319 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1325 elanfreq= [X86-32]
1333 See Documentation/admin-guide/kdump/kdump.rst for details.
1342 Can be useful to work around chipset bugs
1349 0 -- permissive (log only, no denials).
1350 1 -- enforcing (deny and log).
1352 Value can be changed at runtime via
1356 Disable Error Record Serialization Table (ERST)
1374 See also Documentation/fault-injection/.
1378 See Documentation/admin-guide/sysctl/net.rst for
1382 See Documentation/admin-guide/blockdev/floppy.rst.
1385 [IA-64] Avoid check_sal_cache_flush which may hang on
1390 forcepae [X86-32]
1392 Many Pentium M systems disable PAE but may have a
1409 ftrace_filter=[function-list]
1411 tracer at boot up. function-list is a comma separated
1412 list of functions. This list can be changed at run
1416 ftrace_notrace=[function-list]
1418 function-list. This list can be changed at run time
1422 ftrace_graph_filter=[function-list]
1425 function-list is a comma separated list of functions
1426 that can be changed at run time by the
1429 ftrace_graph_notrace=[function-list]
1431 function-list. This list is a comma separated list of
1432 functions that can be changed at run time by the
1438 can be changed at run time by the max_graph_depth file
1451 off -- Don't create device links from firmware info.
1452 permissive -- Create device links from firmware info
1455 on -- Create device links from firmware info and use it
1457 rpm -- Like "on", but also use to order runtime PM.
1463 See also Documentation/input/devices/joystick-parport.rst
1467 gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
1480 The mitigation may have a performance impact but can be
1484 force: Disable AVX to mitigate systems without
1489 off: Disable GDS mitigation.
1491 gcov_persist= [GCOV] When non-zero (default), profiling data for
1524 gpio-mockup.gpio_mockup_ranges
1529 [KNL] Should the hard-lockup detector generate
1535 for 64-bit NUMA, off otherwise.
1538 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1544 Disable Hardware Error Source Table (HEST) support;
1545 corresponding firmware-first mode error processing
1553 highres= [KNL] Enable/disable high resolution timer mode.
1559 hpet= [X86-32,HPET] option to control HPET usage
1560 Format: { enable (default) | disable | force |
1562 disable: disable HPET and use PIT instead
1576 boot-time allocation of gigantic hugepages is skipped.
1584 Documentation/admin-guide/mm/hugetlbpage.rst.
1591 hugepagesz=X hugepages=Y can be specified once for
1594 Documentation/admin-guide/mm/hugetlbpage.rst.
1603 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1604 option. The value selected by this boot parameter can
1609 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1632 (disabled by default, and as a pre-condition
1634 i8042.direct [HW] Put keyboard port into non-translated mode
1635 i8042.dumbkbd [HW] Pretend that controller can only read data from
1640 i8042.noloop [HW] Disable the AUX Loopback command while probing
1648 suspend-to-ram transitions, only during s2r
1683 -1 -- never invert brightness
1684 0 -- machine default
1685 1 -- force brightness inversion
1690 ide-core.nodma= [HW] (E)IDE subsystem
1696 ide-generic.probe-mask= [HW] (E)IDE subsystem
1708 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1713 Poll forces a polling idle loop that can slightly
1719 idle=nomwait: Disable mwait for CPU C-states
1736 legacy only accept legacy-NaN binaries, if supported
1738 2008 only accept 2008-NaN binaries, if supported
1747 'relaxed' straps the emulator for both legacy-NaN and
1748 2008-NaN, whereas 'strict' enables legacy-NaN only on
1757 Ignore loglevel setting - this will print /all/
1765 print warning at first misuse. Can be changed via
1821 Formats: { "ima" | "ima-ng" | "ima-sig" }
1822 Default: "ima-ng"
1834 different crypto accelerators. This option can be used
1842 different crypto accelerators. This option can be used
1854 initcall_blacklist= [KNL] Do not execute a comma-separated list of
1855 initcall functions. Useful for debugging built-in
1878 default (disallow access to all but pkey 0). Can
1888 0 -- basic integrity auditing messages. (Default)
1889 1 -- additional integrity auditing messages.
1895 Disable intel iommu driver.
1902 forcedac [X86-64]
1904 for io virtual address below 32-bit forcing dual
1906 than 32-bit addressing. The default is to look
1907 for translation below 32-bit and if not available
1925 could harm performance of some high-throughput
1932 Disable bounce buffer for untrusted devices such as
1939 1 to 9 specify maximum depth of C-state.
1942 disable
1949 used along with the hardware-managed P-states (HWP)
1953 in favor of acpi-cpufreq. Forcing the intel_pstate driver
1954 instead of acpi-cpufreq may disable platform features, such
1956 P-States information being indicated to OSPM and therefore
1959 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
1972 Allow per-logical-CPU P-State performance control limits using
1975 intremap= [X86-64, Intel-IOMMU]
1977 off disable Interrupt Remapping
1978 nosid disable Source ID checking
1980 BIOS x2APIC opt-out request will be ignored
1981 nopost disable Interrupt Posting
1983 iomem= Disable strict checking of access to MMIO memory
2000 Disable IOMMU bypass, using IOMMU for PCI devices.
2004 0 - Lazy mode.
2010 1 - Strict mode (default).
2017 0 - Use IOMMU translation for DMA.
2018 1 - Bypass the IOMMU for DMA.
2019 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2021 io7= [HW] IO7 for Marvel-based Alpha systems
2036 See Documentation/admin-guide/nfs/nfsroot.rst.
2060 Enables support for pseudo-NMIs in the kernel. This
2079 [Deprecated - use cpusets instead]
2080 Format: [flag-list,]<cpu-list>
2086 Disable the tick when a single task runs.
2103 advised to use cpusets instead to disable scheduler load
2105 It offers a much more flexible interface where CPUs can
2108 You can move a process onto or off an "isolated" CPU via
2111 "number of CPUs in system - 1".
2137 The format of <cpu-list> is described above.
2141 ivrs_ioapic [HW,X86-64]
2142 Provide an override to the IOAPIC-ID<->DEVICE-ID
2144 By default, PCI segment is 0, and can be omitted.
2146 For example, to map IOAPIC-ID decimal 10 to
2152 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2155 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2159 ivrs_hpet [HW,X86-64]
2160 Provide an override to the HPET-ID<->DEVICE-ID
2162 By default, PCI segment is 0, and can be omitted.
2164 For example, to map HPET-ID decimal 10 to
2170 * To map HPET-ID decimal 0 to PCI device 00:14.0
2173 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2177 ivrs_acpihid [HW,X86-64]
2178 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2180 By default, PCI segment is 0, and can be omitted.
2182 For example, to map UART-HID:UID AMD0020:0 to
2188 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2191 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2211 kernelcore= [KNL,X86,IA-64,PPC]
2214 the kernel for non-movable allocations. The requested
2224 subsystem. Note that allocations like PTEs-from-HighMem
2232 for non-movable allocations and remaining memory is used
2243 gdb or control-c on the dbgp connection. When
2244 not using this parameter you use sysrq-g to break into
2249 or a supported polling keyboard driver (non-usb).
2259 characters and can work in polling mode, you can use
2276 Configure the RouterBoard 532 series on-chip
2279 kmemleak= [KNL] Boot-time kmemleak enable/disable
2285 kprobe_event=[probe-list]
2287 The probe-list is a semicolon delimited list of probe
2333 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
2336 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
2338 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
2340 kvm-arm.vgic_v3_group0_trap=
2341 [KVM,ARM] Trap guest accesses to GICv3 group-0
2344 kvm-arm.vgic_v3_group1_trap=
2345 [KVM,ARM] Trap guest accesses to GICv3 group-1
2348 kvm-arm.vgic_v3_common_trap=
2352 kvm-arm.vgic_v4_enable=
2364 kvm-intel.ept= [KVM,Intel] Disable extended page tables
2368 kvm-intel.emulate_invalid_guest_state=
2369 [KVM,Intel] Disable emulation of invalid guest state.
2370 Ignored if kvm-intel.enable_unrestricted_guest=1, as
2376 kvm-intel.flexpriority=
2377 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
2380 kvm-intel.nested=
2384 kvm-intel.unrestricted_guest=
2385 [KVM,Intel] Disable unrestricted guest feature
2389 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2390 CVE-2018-3620.
2396 VMEXIT and VMENTER can leak host memory.
2401 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
2468 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2474 lapic [X86-32,APIC] Enable the local APIC even if BIOS
2478 value for LAPIC timer one-shot implementation. Default
2486 libata.dma=0 Disable all PATA and SATA DMA
2513 first fan-out link behind PMP device. It does not
2520 The following configurations can be forced.
2527 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2539 hot-unplug link recovery
2545 * disable: Disable this device.
2576 Set the number of locking read-acquisition kthreads.
2581 Set the number of locking write-acquisition kthreads.
2584 Set time (s) after boot for CPU-hotplug testing.
2587 Set time (s) between CPU-hotplug operations, or
2588 zero to disable CPU-hotplug testing.
2591 Set task-shuffle interval (jiffies). Shuffling
2592 tasks allows some CPUs to go into dyntick-idle
2597 is useful for hands-off automated testing.
2619 console loglevel will be printed to the console. It can
2630 7 (KERN_DEBUG) debug-level messages
2640 logo.nologo [FB] Disables display of the built-in Linux logo.
2648 lp=auto printer driver. 'lp=reset' (which can be
2658 an IEEE 1284-compliant printer is attached; if
2664 time-consuming boot-time autodetection (up to 250 ms per
2685 machvec= [IA-64] Force the use of a particular machine-vector
2691 Example: machtype=lemote-yeeloong-2f-7inch
2699 bootup you can bring up the other plugged cpu by executing
2706 (loop.max_loop) unconditionally pre-created at init time. The default
2709 devices can be requested on-demand with the
2710 /dev/loop-control interface.
2712 mce [X86-32] Machine Check Exception
2714 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.rst
2717 See Documentation/admin-guide/md.rst.
2724 Control mitigation for the Micro-architectural Data
2728 internal buffers which can forward information to a
2732 forwarded data can be used in a cache side channel
2739 full - Enable MDS mitigation on vulnerable CPUs
2740 full,nosmt - Enable MDS mitigation and disable
2742 off - Unconditionally disable MDS mitigation
2744 On TAA-affected machines, mds=off can be prevented by
2746 mitigated with the same mechanism so in order to disable
2753 For details see: Documentation/admin-guide/hw-vuln/mds.rst
2772 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
2777 per-device physically contiguous DMA buffers.
2785 See Documentation/admin-guide/mm/memory-hotplug.rst.
2789 Such memmap=exactmap lines can be constructed based on
2798 Multiple different regions can be specified,
2810 Example: Exclude memory from 0x18690000-0x1869ffff
2824 memmap=<size>%<offset>-<oldtype>+<newtype>
2826 from <oldtype> to <newtype>. If "-<oldtype>" is left
2841 repeatable BIOS-originated corruption always
2842 affects the same memory, you can use memmap=
2858 default : 0 <disable>
2866 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
2874 Refer to Documentation/virt/kvm/amd-memory-encryption.rst
2875 for details on when memory encryption can be activated.
2878 s2idle - Suspend-To-Idle
2879 shallow - Power-On Suspend or equivalent (if supported)
2880 deep - Suspend-To-RAM or equivalent (if supported)
2881 See Documentation/admin-guide/pm/sleep-states.rst.
2884 See Documentation/admin-guide/media/meye.rst.
2886 mfgpt_irq= [IA-32] Specify the IRQ to use for the
2887 Multi-Function General Purpose Timers on AMD Geode
2890 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
2893 problem by letting the user disable the workaround.
2904 0 - The attached screen is the 3.5" TFT
2905 1 - The attached screen is the 7" TFT
2906 2 - The VGA Shield is attached (1024x768)
2910 b - Enable backlight. The TFT backlight pin will be
2914 c - Enable the s3c camera interface.
2915 t - Reserved for enabling touchscreen support. The
2917 kernel as of 2.6.30, a preliminary port can be found
2919 https://repo.or.cz/w/linux-2.6/mini2440.git
2924 arch-independent options, each of which is an
2925 aggregation of existing arch-specific options.
2928 Disable all optional CPU mitigations. This
2947 ssbd=force-off [ARM64]
2960 have other ways of avoiding SMT-based attacks.
2995 full - Enable mitigation on vulnerable CPUs
2997 full,nosmt - Enable mitigation and disable SMT on
3000 off - Unconditionally disable mitigation
3003 mmio_stale_data=off can be prevented by an active
3006 disable this mitigation, you need to specify
3013 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3021 module_blacklist= [KNL] Do not load a comma-separated list of
3035 movablecore= [KNL,X86,IA-64,PPC]
3046 movable_node [KNL] Boot-time switch to make hotplugable memory
3053 Format: <name>,<region-number>,<size>,<offset>
3056 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3065 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
3069 boundary - index of last SLC block on Flex-OneNAND.
3071 lock - Configure if Flex-OneNAND boundary should be locked.
3078 See arch/arm/mach-s3c2412/mach-jive.c
3106 something different and driver-specific.
3112 0 to disable accounting
3117 See Documentation/admin-guide/nfs/nfsroot.rst.
3119 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3120 See Documentation/admin-guide/nfs/nfsroot.rst.
3123 See Documentation/admin-guide/nfs/nfsroot.rst.
3147 [NFS] enable 64-bit inode numbers.
3148 If zero, the NFS client will fake up a 32-bit inode
3150 of returning the full 64-bit number.
3151 The default is to return 64-bit inode numbers.
3164 that the client can send to the NFSv4.1 server.
3174 disabling idmapping, which can make migration from
3181 [NFS4] Specify an additional fixed unique ident-
3182 ification string that NFSv4 clients can insert into
3212 driver. A non-zero value sets the minimum interval
3224 NMI stack-backtrace request.
3233 0 - turn hardlockup detector in nmi_watchdog off
3234 1 - turn hardlockup detector in nmi_watchdog on
3238 To disable both hard and soft lockup detectors,
3243 These settings can be accessed at runtime via
3251 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3255 no5lvl [X86-64] Disable 5-level paging mode. Forces
3256 kernel to use 4-level paging instead.
3262 Disable suspending of consoles during suspend and
3264 messages can reach various consoles while the rest
3276 Disable device dump. Device dump allows drivers to
3277 append dump data to vmcore so you can collect driver
3278 specified debug info. Drivers can append the data
3281 device dump can help save memory but the driver debug
3287 caches in the slab allocator. Saves per-node memory,
3298 noautogroup Disable scheduler automatic task group creation.
3307 nodelayacct [KNL] Disable per-task delay accounting
3309 nodsp [SH] Disable hardware DSP at boot time.
3311 noefi Disable EFI runtime services support.
3313 no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel.
3315 noexec [IA-64]
3318 On X86-32 available only on PAE configured kernels.
3319 noexec=on: enable non-executable mappings (default)
3320 noexec=off: disable non-executable mappings
3323 Disable SMAP (Supervisor Mode Access Prevention)
3327 Disable SMEP (Supervisor Mode Execution Prevention)
3330 noexec32 [X86-64]
3331 This affects only 32-bit executables.
3332 noexec32=on: enable non-executable mappings (default)
3334 noexec32=off: disable non-executable mappings
3337 nofpu [MIPS,SH] Disable hardware FPU at boot time.
3339 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3341 legacy floating-point registers on task switch.
3343 nohugeiomap [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.
3345 nosmt [KNL,S390] Disable symmetric multithreading (SMT).
3348 [KNL,X86] Disable symmetric multithreading (SMT).
3349 nosmt=force: Force disable SMT, cannot be undone
3352 nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1
3356 nospectre_v2 [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for
3362 [HW] Disable all mitigations for the Speculative Store Bypass vulnerability
3365 [PPC] Don't flush the L1-D cache after accessing user data.
3369 enabling legacy floating-point and sse state.
3394 nohalt [IA-64] Tells the kernel not to use the power saving
3396 power-consumption. On the positive side, it reduces
3397 interrupt wake-up latency, which may improve performance
3399 real-time systems.
3401 nohibernate [HIBERNATION] Disable hibernation and resume.
3403 nohz= [KNL] Boottime enable/disable dynamic ticks
3419 noirqdebug [X86-32] Disables the code which attempts to detect and
3420 disable unhandled interrupt sources.
3430 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
3432 [Deprecated - use intremap=off]
3434 nointroute [IA-64]
3436 noinvpcid [X86] Disable the INVPCID cpu feature.
3438 nojitter [IA-64] Disables jitter checking for ITC timers.
3440 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
3442 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
3445 no-vmw-sched-clock
3446 [X86,PV_OPS] Disable paravirtualized VMware scheduler
3449 no-steal-acc [X86,PV_OPS,ARM64] Disable paravirtualized steal time
3453 nolapic [X86-32,APIC] Do not enable or use the local APIC.
3455 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
3460 nomca [IA-64] Disable machine check abort handling
3462 nomce [X86-32] Disable Machine Check Exception
3464 nomfgpt [X86-32] Disable Multi-Function General Purpose
3467 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
3471 nomodule Disable module load
3473 nopat [X86] Disable PAT (page attribute table extension of
3476 nopcid [X86-64] Disable the PCID cpu feature.
3481 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
3484 nordrand [X86] Disable kernel use of the RDRAND and
3492 no-scroll [VGA] Disables scrollback.
3493 This is required for the Braillex ib80-piezo Braille
3496 nosbagart [IA-64]
3498 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
3501 and disable the IO APIC. legacy for "maxcpus=0".
3503 nosoftlockup [KNL] Disable the soft-lockup detector.
3507 nowatchdog [KNL] Disable both lockup detectors, i.e.
3508 soft-lockup and NMI watchdog (hard-lockup).
3512 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
3520 2. PIC interrupts also depend on CPU0. CPU0 can't be
3525 If the dependencies are under your control, you can
3530 cycles, each HW thread of the CTOP can run
3537 nptcg= [IA-64] Override max number of concurrent global TLB
3545 runtime you can physically add extra cpu until it reaches
3546 n. So during boot up some boot time memory for per-cpu
3547 variables need be pre-allocated for later physical cpu
3552 numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing.
3553 Allowed values are enable and disable
3556 'node', 'default' can be specified
3557 This can be set from sysctl after boot.
3558 See Documentation/admin-guide/sysctl/vm.rst for details.
3561 See Documentation/core-api/debugging-via-ohci1394.rst for more
3600 running on a platform with a direct-mapped memory-side
3601 cache, and this parameter can be used to
3602 override/disable that behavior. The state of the flag
3603 can be read from sysfs at:
3606 page_owner= [KNL] Boot-time page_owner enabling option.
3609 we can turn it on.
3612 page_poison= [KNL] Boot-time parameter changing the state of
3625 User can chose combination of the following bits:
3638 The optional switch "nousertaint" can be utilized to
3642 See Documentation/admin-guide/tainted-kernels.rst for
3643 extra details on the taint flags that users can pick
3650 Run kdump after running panic-notifiers and dumping
3654 because some panic notifiers can make the crashed
3669 possible conflicts). You can specify the base
3695 See also Documentation/admin-guide/blockdev/paride.rst.
3714 addresses can be specified after the base
3724 bios [X86-32] force use of PCI BIOS, don't access
3726 has a non-standard PCI host bridge.
3727 nobios [X86-32] disallow use of PCI BIOS, only direct
3733 data in IO port 0xCFC, both 32-bit).
3735 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
3736 the function, IO port 0xCFA, also 8-bit, sets
3738 through ports 0xC000-0xCFFF).
3742 enabled, this kernel boot option can be used to
3743 disable the use of PCIE advanced error reporting.
3744 nodomains [PCI] Disable support for multiple PCI
3745 root domains (aka PCI segments, in ACPI-speak).
3746 nommconf [X86] Disable use of MMCONFIG for PCI
3752 enabled, this kernel boot option can be used to
3753 disable the use of MSI interrupts system-wide.
3754 noioapicquirk [APIC] Disable all boot interrupt quirks.
3758 primary IO-APIC for bridges that cannot disable
3761 noioapicreroute [APIC] Disable workaround that uses the
3765 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
3783 assigned automatically to PCI devices. You can
3789 F0000h-100000h range.
3790 lastbus=N [X86] Scan all buses thru bus #N. Can be
3794 assign-busses [X86] Always assign all PCI bus
3815 skip_isa_align [X86] do not align io start addr, so can
3822 bfsort Sort PCI devices into breadth-first order.
3825 nobfsort Don't sort PCI devices into breadth-first order.
3826 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
3827 tuning and use the BIOS-configured MPS defaults.
3834 or bus can support) for best performance.
3837 configuration allows peer-to-peer DMA between
3840 that hot-added devices will work.
3855 A PCI-PCI bridge can be specified if resource
3861 for 4096-byte alignment.
3862 ecrc= Enable/disable PCIe ECRC (transaction layer
3863 end-to-end CRC checking).
3884 realloc= Enable/disable reallocating PCI bridge resources
3892 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
3899 can resize a BAR to allow access to all VRAM.
3917 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
3919 off Disable ASPM.
3928 dpc-native Use native PCIe service for DPC only. May
3930 compat Disable native PCIe services (PME, AER, DPC, PCIe
3934 off Disable power management of all PCIe ports
3945 Keep all power-domains already enabled by bootloader on,
3951 See Documentation/admin-guide/blockdev/paride.rst.
3953 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
3966 See Documentation/admin-guide/blockdev/paride.rst.
3969 See Documentation/admin-guide/blockdev/paride.rst.
3971 pirq= [SMP,APIC] Manual mp-table setup
3972 See Documentation/x86/i386/IO-APIC.rst.
3976 See also Documentation/admin-guide/parport.rst.
3987 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
3996 { on | off | curr | res | no-curr | no-res }
4032 Disable Hardware Transactional Memory
4034 print-fatal-signals=
4040 coredump - etc.
4043 you might want to try "ulimit -i unlimited".
4050 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4055 on - unlimited logging to /dev/kmsg from userspace
4056 off - logging to /dev/kmsg disabled
4057 ratelimit - ratelimit the logging
4061 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4064 Limit processor to maximum C-state
4068 Ignore the _CST method to determine C-states,
4075 Param: "schedule" - profile schedule points.
4076 Param: "sleep" - profile D-state sleeping (millisecs).
4078 Param: "kvm" - profile VM exits.
4079 Param: <number> - step/bucket size as a power of 2 for
4089 psi= [KNL] Enable or disable pressure stall information
4109 See Documentation/admin-guide/blockdev/paride.rst.
4111 pti= [X86-64] Control Page Table Isolation of user and
4116 on - unconditionally enable
4117 off - unconditionally disable
4118 auto - kernel detects whether your CPU model is
4123 nopti [X86-64]
4127 [KNL] Number of legacy pty's. Overwrites compiled-in
4130 quiet [KNL] Disable most log messages
4135 See Documentation/admin-guide/md.rst.
4138 See Documentation/admin-guide/blockdev/ramdisk.rst.
4143 [KNL] Enable or disable trusting the use of the
4149 [KNL] Enable or disable trusting the use of a
4154 ras=option[,option,...] [KNL] RAS-specific options
4157 Disable the Correctable Errors Collector,
4162 except that the string "all" can be used to
4166 the specified list of CPUs to be no-callback CPUs.
4169 purpose, where "x" is "p" for RCU-preempt, and
4170 "s" for RCU-sched, and "N" is the CPU number.
4172 which can be useful for HPC and real-time
4173 workloads. It can also improve energy efficiency
4181 This improves the real-time response for the
4198 RCU grace-period cleanup.
4202 RCU grace-period initialization.
4206 RCU grace-period pre-initialization, that is,
4207 the propagation of recent CPU-hotplug changes up
4212 per-CPU rcuc kthreads. Defaults to a non-zero
4217 Disable autobalancing of the rcu_node combining
4220 cache-to-cache transfer latencies.
4226 and for NUMA systems with large remote-access
4239 Set delay from grace-period initialization to
4252 soliciting quiescent-state help from
4264 Set the SCHED_FIFO priority of the RCU per-CPU
4267 and for the RCU grace-period kthreads (rcu_bh,
4269 set, valid values are 1-99 and the default is 1
4270 (the least-favored priority). Otherwise, when
4271 RCU_BOOST is not set, valid values are 0-99 and
4272 the default is zero (non-realtime operation).
4278 the wakeup overhead on the global grace-period
4280 each group's NOCB grace-period kthread.
4288 batch limiting is re-enabled.
4292 RCU's force-quiescent-state scan will aggressively
4297 disable more aggressive help enlistment.
4306 Lazy RCU callbacks are those which RCU can
4310 Cause the grace-period kthread to get an extra
4312 it should at force-quiescent-state time.
4318 this specifies an rcu_read_unlock()-time delay
4322 of RCU-protected pointers after the relevant
4332 grace-period primitives such as call_rcu().
4343 grace-period primitives.
4346 Set test-start holdoff period. The purpose of
4365 Set number of RCU readers. The value -1 selects
4367 "n" less than -1 selects N-n+1, where N is again
4368 the number of CPUs. For example, -2 selects N
4369 (the number of CPUs), -3 selects N+1, and so on.
4370 A value of "n" less than or equal to -N selects
4383 complete. This is useful for hands-off automated
4390 Write-side holdoff between grace periods,
4407 Enable RCU grace-period forward-progress testing
4411 Specify the fraction of a CPU-stall-warning
4412 period to do tight-loop forward-progress testing.
4416 forward-progress tests.
4420 need_resched() during tight-loop forward-progress
4424 Use conditional/asynchronous update-side
4428 Use expedited update-side primitives, if available.
4431 Use normal (non-expedited) asynchronous
4432 update-side primitives, if available.
4435 Use normal (non-expedited) synchronous
4436 update-side primitives, if available. If all
4440 they are all non-zero.
4448 Leak an RCU-protected pointer out of the reader.
4449 This can of course result in splats, and is
4463 Set number of RCU readers. The value -1 selects
4464 N-1, where N is the number of CPUs. A value
4465 "n" less than -1 selects N-n-2, where N is again
4466 the number of CPUs. For example, -2 selects N
4467 (the number of CPUs), -3 selects N+1, and so on.
4470 Enable debug-object double-call_rcu() testing.
4473 Set time (s) after boot for CPU-hotplug testing.
4476 Set time (jiffies) between CPU-hotplug operations,
4477 or zero to disable CPU-hotplug testing.
4480 Set the number of read-then-exit kthreads used
4482 task-exit processing.
4485 The number of times in a given read-then-exit
4486 episode that a set of read-then-exit kthreads
4491 read-then-exit testing episodes.
4494 Set task-shuffle interval (s). Shuffling tasks
4495 allows some CPUs to go into dyntick-idle mode
4500 is useful for hands-off automated testing.
4504 warnings, zero to disable.
4509 to any other stall-related activity.
4515 Disable interrupts while stalling if set.
4519 grace-period kthread to test RCU CPU stall
4520 warnings, zero to disable. If both stall_cpu
4545 Test RCU's dyntick-idle handling. See also the
4571 Use expedited grace-period primitives, for
4574 but can increase CPU utilization, degrade
4575 real-time latency, and degrade energy efficiency.
4579 Use only normal grace-period primitives,
4582 real-time latency, CPU utilization, and
4583 energy efficiency, but can expose users to
4584 increased grace-period latency. This parameter
4591 only normal grace-period primitives. No effect
4598 number avoids disturbing real-time workloads,
4603 messages. Disable with a value less than or equal
4615 force - Override the decision by the kernel to hide the
4643 Set test-start holdoff period. The purpose of
4652 but the default has already reduced the per-pass
4657 Set number of readers. The default value of -1
4666 Set the read-side critical-section duration,
4670 Specify the read-protection implementation to test.
4683 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
4691 reservetop= [X86-32]
4713 See Documentation/power/swsusp-and-swap-files.rst
4726 no Disable hibernation and resume.
4729 during restoration read-only).
4737 AMD-based UNRET and IBPB mitigations alone do not stop
4739 sibling threads. For that reason, STIBP is used on pro-
4743 off - no mitigation
4744 auto - automatically select a migitation
4745 auto,nosmt - automatically select a mitigation,
4749 ibpb - On AMD, mitigate short speculation
4754 ibpb,nosmt - Like "ibpb" above but will disable SMT
4758 unret - Force enable untrained return thunks,
4759 only effective on AMD f15h-f17h based
4761 unret,nosmt - Like unret, but will disable SMT when STIBP
4785 ring3mwait=disable
4786 [KNL] Disable ring 3 MONITOR/MWAIT feature on supported
4789 ro [KNL] Mount root device read-only on boot
4792 on Mark read-only kernel memory as read-only (default).
4793 off Leave read-only kernel memory writable for debugging.
4798 debug-uart get routed to the D+ and D- pins of the usb
4820 rw [KNL] Mount root device read-write on boot
4838 schedstats= [KNL,X86] Enable or disable scheduled statistics.
4839 Allowed values are enable and disable. This feature
4862 to 10 seconds for built-in smp_call_function()
4869 that requesting even small non-zero numbers of
4870 seconds can result in RCU CPU stall warnings,
4876 The default of -1 specifies a number of kthreads
4881 test before initiating CPU-hotplug operations.
4885 CPU-hotplug operations. Specifying zero (which
4886 is the default) disables CPU-hotplug operations.
4892 Non-zero values are useful for automated tests.
4905 preempt_disable() to disable CPU hotplug
4915 "wait" parameter. A value of -1 selects the
4916 default if all other weights are -1. However,
4918 value of -1 will instead select a weight of zero.
4923 non-zero "wait" parameter. See weight_single.
4930 this weighting can place serious IPI load
4936 non-zero "wait" parameter. See weight_single
4948 non-zero "wait" parameter. See weight_single
4955 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
4956 1 -- enable.
4964 selinux= [SELINUX] Disable or enable SELinux at boot time.
4967 0 -- disable.
4968 1 -- enable.
4971 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
4974 0 -- disable.
4975 1 -- enable.
4978 serialnumber [BUGS=X86-32]
4983 simeth= [IA-64]
4989 Disable merging of slabs with similar size. May be
4993 layout control by attackers can usually be
4997 unchanged). Debug options disable merging on their
5010 slub_debug can create guard zones around objects and
5017 memory cgroup sub-caches. 1 to enable, 0 to disable.
5019 Enabling this can lead to a very high number of debug
5050 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
5051 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
5052 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
5053 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
5054 smsc-ircc2.ircc_irq= [HW] IRQ line
5055 smsc-ircc2.ircc_dma= [HW] DMA channel
5056 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
5066 Default: -1 (no limit)
5069 [KNL] Should the soft-lockup detector generate panics.
5072 A value of 1 instructs the soft-lockup detector
5073 to panic the machine when a soft-lockup occurs. It is
5076 respective build-time switch to that functionality.
5079 [KNL] Should the soft-lockup detector generate
5084 See Documentation/admin-guide/laptops/sonypi.rst
5091 on - unconditionally enable, implies
5093 off - unconditionally disable, implies
5095 auto - kernel detects whether your CPU model is
5107 Selecting 'off' will disable both the kernel and
5110 Specific mitigations can also be selected manually:
5112 retpoline - replace indirect branches
5113 retpoline,generic - Retpolines
5114 retpoline,lfence - LFENCE; indirect branch
5115 retpoline,amd - alias for retpoline,lfence
5116 eibrs - Enhanced/Auto IBRS
5117 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
5118 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
5119 ibrs - use IBRS to protect kernel
5129 on - Unconditionally enable mitigations. Is
5132 off - Unconditionally disable mitigations. Is
5135 prctl - Indirect branch speculation is enabled,
5136 but mitigation can be enabled via prctl
5141 - Like "prctl" above, but only STIBP is
5147 - Same as "prctl" above, but all seccomp
5152 - Like "seccomp" above, but only STIBP is
5157 auto - Kernel selects the mitigation depending on
5169 off - Disable mitigation
5170 microcode - Enable microcode mitigation only
5171 safe-ret - Enable sw-only safe RET mitigation (default)
5172 ibpb - Enable mitigation by issuing IBPB on
5174 ibpb-vmexit - Issue IBPB only on VMEXIT
5175 (cloud-specific mitigation)
5178 [HW] Control Speculative Store Bypass (SSB) Disable mitigation
5186 is that such stores are unlikely and that they can
5191 store can be used in a cache side channel attack, for
5200 on - Unconditionally disable Speculative Store Bypass
5201 off - Unconditionally enable Speculative Store Bypass
5202 auto - Kernel detects whether the CPU model contains an
5208 prctl - Control Speculative Store Bypass per thread
5212 seccomp - Same as "prctl" above, but all seccomp threads
5213 will disable SSB unless they explicitly opt out.
5220 on,auto - On Power8 and Power9 insert a store-forwarding
5224 off - No action.
5241 off - not enabled
5243 warn - the kernel will emit rate limited warnings
5248 fatal - the kernel will send SIGBUS to applications
5260 Certain CPUs are vulnerable to an MDS-like
5261 exploit which can leak bits from the random
5265 microcode. However, the microcode fix can cause
5270 The microcode mitigation can be disabled with
5273 off: Disable mitigation and remove
5278 grace-period sequence counter wrap for the
5279 srcu_data structure's ->srcu_gp_seq_needed field.
5290 expediting. Set to zero to disable automatic
5294 Speculative Store Bypass Disable control
5301 force-on: Unconditionally enable mitigation for
5303 force-off: Unconditionally disable mitigation for
5320 stacktrace_filter=[function-list]
5322 will trace at boot up. function-list is a comma separated
5323 list of functions. This list can be changed at run
5330 Set the STI (builtin display/keyboard on the HP-PARISC
5332 as the initial boot-console.
5373 to global on non-NUMA machines)
5379 RPC calls that can be sent from the client to a
5398 controller if no parameter or 1 is given or disable
5399 it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)
5401 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
5403 <int> -- Number of I/O TLB slabs
5404 force -- force using of bounce buffers even if they
5406 noforce -- Never use bounce buffers (for debugging)
5420 Enable/disable old style sysfs layout for old udev
5430 Ignore sysrq setting - this boot parameter will
5438 cache size. See Documentation/networking/ip-sysctl.rst
5444 Specify "mem" (for Suspend-to-RAM) or "standby" (for
5449 wakeup-capable RTC alarm.
5455 -1: disable all active trip points in all thermal zones
5459 -1: disable all critical trip points in all thermal zones
5463 Set to disable actions on ACPI thermal zone
5467 1: disable ACPI thermal control
5470 -1: disable all passive trip points
5476 <deci-seconds>: poll all this frequency
5498 Prevent the CPU-hotplug component of torturing
5502 Dump the ftrace buffer at torture-test shutdown,
5503 even if there were no errors. This can be a
5506 with rotating-rust storage.
5522 trace_event=[event-list]
5524 to facilitate early boot debugging. The event-list is a
5528 trace_options=[option-list]
5529 [FTRACE] Enable or disable tracer options at boot.
5530 The option-list is a comma delimited list of options
5531 that can be enabled or disabled just as if you were
5559 frequency tracepoints such as irq or sched, can cause
5563 [FTRACE] enable this option to disable tracing when a
5564 warning is hit. This turns off "tracing_on". Tracing can
5572 This option can also be set at run time via the sysctl
5578 Can be used to control the default behavior of the system
5580 See Documentation/admin-guide/mm/transhuge.rst
5583 tsc= Disable clocksource stability checks for TSC.
5588 high-resolution timer mode on older hardware, and in
5591 Used to run time disable IRQ_TIME_ACCOUNTING on any
5593 can add overhead.
5597 [x86] nowatchdog: disable clocksource watchdog. Used
5614 on - Enable TSX on the system. Although there are
5617 several previous speculation-related CVEs, and
5621 off - Disable TSX on the system. (Note that this
5629 auto - Disable TSX if X86_BUG_TAA is present,
5634 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5640 Similar to Micro-architectural Data Sampling (MDS)
5643 exploit against CPU internal buffers which can forward
5648 data can be used in a cache side channel attack, to
5655 full - Enable TAA mitigation on vulnerable CPUs
5658 full,nosmt - Enable TAA mitigation and disable SMT on
5661 vulnerable to cross-thread TAA attacks.
5662 off - Unconditionally disable TAA mitigation
5664 On MDS-affected machines, tsx_async_abort=off can be
5666 are mitigated with the same mechanism so in order to disable
5676 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
5682 See also Documentation/input/devices/joystick-parport.rst
5684 udbg-immortal [PPC] When debugging early kernel crashes that
5690 Set number of hash buckets for UDP/UDP-Lite connections
5692 uhci-hcd.ignore_oc=
5694 Some badly-designed motherboards generate lots of
5705 (default -1 = authorized except for wireless USB,
5711 for newly-detected USB devices (default 2). This
5739 [USB] Specifies timeout for the initial 64-byte
5743 usbcore.nousb [USB] Disable the USB subsystem
5746 [USB] A list of quirk entries to augment the built-in
5749 VendorID:ProductID:Flags. The IDs are 4-digit hex
5751 will change the built-in quirk; setting it if it is
5756 a 255-byte read);
5757 b = USB_QUIRK_RESET_RESUME (device can't resume
5759 c = USB_QUIRK_NO_SET_INTF (device can't handle
5760 Set-Interface requests);
5761 d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't
5764 e = USB_QUIRK_RESET (device can't be reset
5768 bNumInterfaces count, and can't handle
5779 (bInterval-1).
5784 i = USB_QUIRK_DEVICE_QUALIFIER (device can't
5790 k = USB_QUIRK_NO_LPM (device can't handle Link
5814 usb-storage.delay_use=
5818 usb-storage.quirks=
5820 override the built-in unusual_devs list. List
5823 and Product ID values (4-digit hex numbers) and
5825 to a common usb-storage quirk flag as follows:
5867 medium is write-protected).
5876 1 - undefined instruction events
5877 2 - system calls
5878 4 - invalid data aborts
5879 8 - SIGSEGV faults
5880 16 - SIGBUS faults
5894 vdso=0: disable VDSO mapping
5896 vdso32= [X86] Control the 32-bit vDSO
5897 vdso32=1: enable 32-bit VDSO
5898 vdso32=0 or vdso32=2: disable 32-bit VDSO
5908 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
5910 vector= [IA-64,SMP]
5930 <size> := size (can use standard suffixes
5939 Can be used multiple times for multiple devices.
5941 vga= [BOOT,X86-32] Select a particular video mode
5943 Documentation/admin-guide/svga.rst.
5958 - Disable all of the above options
5961 size of <nn>. This can be used to increase the
5962 minimum size (128MB on x86). It can also be used to
5979 vsyscall= [X86-64]
5982 code). Most statically-linked binaries and older
5985 targets for exploits that can control RIP.
6006 see VGA-softcursor.txt. Default: 2 = underline.
6011 This is a 16-member array composed of values
6012 ranging from 0-255.
6017 This is a 16-member array composed of values
6018 ranging from 0-255.
6023 This is a 16-member array composed of values
6024 ranging from 0-255.
6029 Set system-wide default UTF-8 mode for all tty's.
6030 Default is 1, i.e. UTF-8 mode is enabled for all
6035 Format=<-1|0|1>
6036 Set system-wide default for whether a cursor
6037 is shown on new VTs. Default is -1,
6042 vt.italic= [VT] Default color for italic text; 0-15.
6045 vt.underline= [VT] Default color for underlined text; 0-15.
6049 see Documentation/watchdog/watchdog-parameters.rst
6050 or other driver-specific files in the
6062 If CONFIG_WQ_WATCHDOG is configured, workqueue can
6067 it can be updated at runtime by writing to the
6075 whatever reason, this option can be used. Note
6076 that this also can be controlled per-workqueue for
6080 Per-cpu workqueues are generally preferred because
6082 locality; unfortunately, per-cpu workqueues tend to
6085 Enabling this makes the per-cpu workqueues which
6100 forces round-robin CPU selection to flush out
6108 on - Enable writecombine, use WUC for ioremap_wc()
6109 off - Disable writecombine, use SUC for ioremap_wc()
6111 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
6115 x86_intel_mid_timer= [X86-32,APBT]
6121 xen_512gb_limit [KNL,X86-64,XEN]
6131 ide-disks -- unplug primary master IDE devices
6132 aux-ide-disks -- unplug non-primary-master IDE devices
6133 nics -- unplug network devices
6134 all -- unplug all emulated devices (NICs and IDE disks)
6135 unnecessary -- unplugging emulated devices is
6138 never -- do not unplug even if version check succeeds
6156 [KNL,X86,XEN] Disable the vector callback for Xen
6161 to Xen, for use by other domains. Can be also changed at runtime
6165 xen_timer_slop= [X86-64,XEN]
6188 Boolean parameter to disable using fifo event handling
6190 preferred over the 2-level event handling, as it is
6217 xhci-hcd.quirks [USB,KNL]
6219 host controller quirks. Meaning of each bit can be
6235 can be written using xmon commands.
6237 memory, and other data can't be written using