Lines Matching +full:boot +full:- +full:time
5 avoid prolonged boot times. The lazy option will add
10 at once during boot.
16 force -- enable ACPI if default was off
17 on -- enable ACPI but allow fallback to DT [arm64,riscv64]
18 off -- disable ACPI if default was on
19 noirq -- do not use ACPI for IRQ routing
20 strict -- Be less tolerant of platforms that are not
22 rsdt -- prefer RSDT over (default) XSDT
23 copy_dsdt -- copy DSDT to memory
24 nocmcff -- Disable firmware first mode for corrected
28 nospcr -- disable console in ACPI SPCR table as
45 If set to vendor, prefer vendor-specific driver
77 Documentation/firmware-guide/acpi/debug.rst for more information about
135 Format: <byte> or <bitmap-list>
138 Disable auto-serialization of AML methods
141 auto-serialization feature.
149 Disable installation of static SSDTs at early boot time
159 Ignore the ACPI-based watchdog interface (WDAT) and let
164 on machines running EFI runtime service to boot the
180 acpi_osi=! # disable all built-in OS vendor
182 acpi_osi=!! # enable all built-in OS vendor
244 For broken nForce2 BIOS resulting in XT-PIC timer.
253 as soon as the kernel's real-mode entry point is called.
291 See Documentation/sound/alsa-configuration.rst
298 align_va_addr= [X86-64]
300 allocating a VMA at process creation time. This option
303 CPU-intensive style benchmark, and it can vary highly in
306 32: only for 32-bit processes
307 64: only for 64-bit processes
308 on: enable for both 32- and 64-bit processes
309 off: disable for both 32- and 64-bit processes
312 Allocate the ftrace snapshot buffer on boot up when the
314 and you need to use tracing_snapshot() on boot up, and
319 Allow execve() of 32-bit applications and setting of the
321 subset of the CPUs support 32-bit EL0. When this
322 parameter is present, the set of CPUs supporting 32-bit
324 and hot-unplug operations may be restricted.
326 See Documentation/arch/arm64/asymmetric-32bit.rst for more
329 amd_iommu= [HW,X86-64]
332 fullflush - Deprecated, equivalent to iommu.strict=1
333 off - do not initialize any AMD IOMMU found in
335 force_isolation - Force device isolation for all
340 force_enable - Force enable the IOMMU on platforms known
343 pgtbl_v1 - Use v1 page table for DMA-API (Default).
344 pgtbl_v2 - Use v2 page table for DMA-API.
345 irtcachedis - Disable Interrupt Remapping Table (IRT) caching.
346 nohugepages - Limit page-sizes used for v1 page-tables
348 v2_pgsizes_only - Limit page-sizes used for v1 page-tables
352 amd_iommu_dump= [HW,X86-64]
358 amd_iommu_intr= [HW,X86-64]
361 legacy - Use legacy interrupt remapping mode.
362 vapic - Use virtual APIC mode, which allows IOMMU
364 This mode requires kvm-amd.avic=1.
393 Disable amd-pstate preferred core.
406 Power management functions (SPARCstation-4/5 + deriv.)
408 Disable APC CPU standby support. SPARCstation-Fox does
409 not play well with APC CPU idle - disable it if you have
412 apic [APIC,X86-64] Use IO-APIC. Default.
418 when initialising the APIC and IO-APIC components.
439 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
442 0 -- disable.
443 1 -- enable.
446 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
497 audit= [KNL] Enable the audit sub-system
499 0 | off - kernel audit is disabled and can not be
501 unset - kernel audit is initialized but disabled and
503 1 | on - kernel audit is initialized and partially
516 0 - Disable the BAU.
517 1 - Enable the BAU.
518 unset - Disable the BAU.
557 See Documentation/block/cmdline-partition.rst
560 Milliseconds to delay each printk during boot.
571 See Documentation/admin-guide/bootconfig.rst
576 bttv.pll= See Documentation/admin-guide/media/bttv.rst
581 at a time.
585 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
593 [NET] Specifies amount of time (in seconds) that
604 inclusive. See arch/mips/include/asm/pgtable-bits.h
611 cfi= [X86-64] Set Control Flow Integrity checking features
622 norand: Do not re-randomize CFI hashes.
632 - foo isn't auto-mounted if you mount all cgroups in
634 - foo isn't visible as an individually mountable
636 - if foo is an optional feature then the feature is
642 Specifying "pressure" disables per-cgroup pressure
659 semi-legacy software can check this file to decide
668 nosocket -- Disable socket memory accounting.
669 nokmem -- Disable kernel memory accounting.
670 nobpf -- Disable BPF memory accounting.
675 0 -- check protection applied by kernel (includes
677 1 -- check protection requested by application.
689 numbers X. Note the Linux-specific bits are not necessarily
690 stable over kernel options, but the vendor-specific
710 force such clocks to be always-on nor does it reserve
714 information, see Documentation/driver-api/clk.rst.
716 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
733 [X86-32] pit,hpet,tsc;
740 [X86-64] hpet,tsc
746 architected timer so that code using WFE-based polling
760 clocksource-wdtest.holdoff= [KNL]
761 Set the time in seconds that the clocksource
766 cma=nn[MG]@[start[MG][-end[MG]]]
777 Sets the size of kernel per-numa memory area for
779 per-numa CMA altogether. And If this option is not
781 With per-numa CMA enabled, DMA users on node nid will
808 com20020= [HW,NET] ARCnet - COM20020 chipset
812 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
816 ARCnet - COM90xx chipset (memory-mapped buffers)
829 This leads to a much faster boot time when a 3270
845 See Documentation/admin-guide/serial-console.rst for more
860 $ ls -d /sys/bus/serial-base/devices/*:*.*/tty/*
861 /sys/bus/serial-base/devices/00:04:0.0/tty/ttyS0
874 Start an early, polled-mode console on the 8250/16550
877 MMIO inter-register address stride is either 8-bit
878 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
882 the h/w is not re-initialized.
902 "[time stamp] text\n" format (time stamp may not be
906 Switch to syslog format: "<%u>[time stamp] text\n"
909 syscall, or to executing "dmesg -S --raw" or to reading
926 1: enable debugging at boot time
933 disable the cpuidle sub-system
939 disable the cpufreq sub-system
947 [X86,EARLY] Delay for N microsec between assert and de-assert
949 on every CPU online, such as boot, and resume from suspend.
968 like Hyper-V, PowerPC (fadump) and AMD SEV-SNP.
976 [KNL, X86-64, ARM64, RISCV, LoongArch] Select a region
979 See Documentation/admin-guide/kdump/kdump.rst for further details.
984 start-[end] where start and end are both
986 Documentation/admin-guide/kdump/kdump.rst for an example.
989 [KNL, X86-64, ARM64, RISCV, LoongArch] range could be
997 [KNL, X86-64, ARM64, RISCV, LoongArch] range under 4G.
1003 for 32-bit devices won't run out. Kernel would try to allocate
1006 --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
1007 --> arm64: 128MiB
1008 --> riscv: 128MiB
1009 --> loongarch: 128MiB
1039 [KNL] Disable crypto self-tests
1047 csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
1062 See also Documentation/input/devices/joystick-parport.rst
1068 boot sequence. If enabled, we use a weak hash instead
1075 [KNL] verbose locking self-tests
1078 self-tests.
1080 (no extra messages), setting it to -1 (all bits set)
1081 will print _a_lot_ more information - normally only
1107 enables the feature at boot time. By default, it is
1116 Format: { on, no-mount, off }
1118 no-mount:
1123 get a -EPERM as result when trying to register files
1127 Default value is set in build-time with a kernel configuration.
1139 Documentation/admin-guide/mm/hugetlbpage.rst.
1147 of 0 will timeout at the end of initcalls. If the time
1153 delayacct [KNL] Enable per-task delay accounting
1235 this option disables the debugging code at boot.
1239 entries for DMA-API debugging code. One entry is
1240 required per DMA-API allocation. Use this if the
1241 DMA-API debugging code disables itself because the
1245 With this option the DMA-API debugging driver
1246 filter feature can be enabled at boot time. Just
1262 This parameter overrides the compile time default set
1269 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
1294 Control how the dt_cpu_ftrs device-tree binding is
1304 what data is available or for reverse-engineering.
1308 Enable debug messages at boot time. See
1309 Documentation/admin-guide/dynamic-debug-howto.rst
1320 determined by stdout-path property in device tree's
1325 Start an early, polled-mode console on a Cadence
1336 Start an early, polled-mode console on the 8250/16550
1338 MMIO inter-register address stride is either 8-bit
1339 (mmio) or 32-bit (mmio32 or mmio32be).
1349 Start an early, polled-mode console on a pl011 serial
1353 the driver will use only 32-bit accessors to read/write
1362 Start an early, polled-mode console on a meson serial
1368 Start an early, polled-mode console on an msm serial
1374 Start an early, polled-mode console on an msm serial
1380 Start an early, polled-mode console on a serial port
1386 Start an early, polled-mode console on a serial port
1392 Use RISC-V SBI (Supervisor Binary Interface) for early
1410 Start an early, polled-mode console on a lantiq serial
1424 Start an early, polled-mode, output-only console on the
1429 Start an early, polled-mode console on the
1435 Start an early, polled-mode console on a Qualcomm
1443 coherent non-x86 systems that use system memory for
1477 be used at a time.
1521 PCI bridges while in the EFI boot stub.
1523 boot stub, as chunking can cause problems with some
1534 on all PCI bridges while in the EFI boot stub
1546 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1556 the boot argument: earlyprintk=vga
1560 very early in the boot process. For early debugging
1563 elanfreq= [X86-32]
1571 See Documentation/admin-guide/kdump/kdump.rst for details.
1587 0 -- permissive (log only, no denials).
1588 1 -- enforcing (deny and log).
1607 stages so cover more early boot allocations.
1610 memory initialization is disabled) so the boot process
1621 See also Documentation/fault-injection/.
1625 See Documentation/admin-guide/sysctl/net.rst for
1629 See Documentation/admin-guide/blockdev/floppy.rst.
1631 forcepae [X86-32]
1638 fred= [X86-64]
1647 boot debugging.
1650 [FTRACE] On boot up, a snapshot will be taken of the
1654 boot up that is likely to be overridden by user space
1664 a snapshot at the end of boot up.
1689 ftrace_filter=[function-list]
1691 tracer at boot up. function-list is a comma-separated
1693 time by the set_ftrace_filter file in the debugfs
1696 ftrace_notrace=[function-list]
1698 function-list. This list can be changed at run time
1702 ftrace_graph_filter=[function-list]
1704 by the function graph tracer at boot up.
1705 function-list is a comma-separated list of functions
1706 that can be changed at run time by the
1709 ftrace_graph_notrace=[function-list]
1711 function-list. This list is a comma-separated list of
1712 functions that can be changed at run time by the
1718 can be changed at run time by the max_graph_depth file
1726 (suppliers first, then consumers), supplier boot state
1731 off -- Don't create device links from firmware info.
1732 permissive -- Create device links from firmware info
1733 but use it only for ordering boot state clean
1735 on -- Create device links from firmware info and use it
1737 rpm -- Like "on", but also use to order runtime PM.
1750 strict -- Default. Continue waiting on consumers to
1752 timeout -- Give up waiting on consumers and call
1762 See also Documentation/input/devices/joystick-parport.rst
1766 gart_fix_e820= [X86-64,EARLY] disable the fix e820 for K8 GART
1792 gcov_persist= [GCOV] When non-zero (default), profiling data for
1796 debugfs files are removed at module unload time.
1802 gpio-mockup.gpio_mockup_ranges
1805 gpio-mockup.gpio_mockup_named_lines
1833 hardening is enabled for this boot. Hardened
1837 against bounds-checking flaws in the kernel's
1845 [KNL] Should the hard-lockup detector generate
1861 auto - Hash pointers unless slab_debug is enabled.
1862 always - Always hash pointers (even if slab_debug is
1864 never - Never hash pointers. This option should only
1866 not use on production kernels. The boot
1870 hashdist= [KNL,NUMA] Large hashes allocated during boot
1872 for 64-bit NUMA, off otherwise.
1880 corresponding firmware-first mode error processing
1885 present during boot.
1890 during restoration read-only).
1910 highmem=nn[KMG] [KNL,BOOT,EARLY] forces the highmem zone to have an exact
1934 hpet= [X86-32,HPET] option to control HPET usage
1945 hugepages= [HW,EARLY] Number of HugeTLB pages to allocate at boot.
1951 number of pages to allocate per-node can be specified.
1952 See also Documentation/admin-guide/mm/hugetlbpage.rst.
1959 allocate huge pages of a specific size at boot. The
1963 Documentation/admin-guide/mm/hugetlbpage.rst.
1968 allocate hugepages during boot. This option can be
1969 used to improve system bootup time when allocating
1973 Note that this parameter only applies to non-gigantic huge pages.
1983 boot-time allocation of gigantic hugepages is skipped.
2018 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
2019 option. The value selected by this boot parameter can
2024 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
2046 Set device-properties for ACPI-enumerated I2C-attached
2047 touchscreen, to e.g. fix coordinates of upside-down
2055 Omit "=<val>" entirely Set a boolean device-property
2056 Unsigned number Set a u32 device-property
2057 Anything else Set a string device-property
2060 i2c_touchscreen_props=GDIX1001:touchscreen-inverted-x:
2061 touchscreen-inverted-y
2063 i2c_touchscreen_props=MSSL1680:touchscreen-size-x=1920:
2064 touchscreen-size-y=1080:touchscreen-inverted-y:
2065 firmware-name=gsl1680-vendor-model.fw:silead,home-button
2070 (disabled by default, and as a pre-condition
2072 i8042.direct [HW] Put keyboard port into non-translated mode
2086 suspend-to-ram transitions, only during s2r
2110 -1 -- never invert brightness
2111 0 -- machine default
2112 1 -- force brightness inversion
2114 ia32_emulation= [X86-64]
2116 When true, allows loading 32-bit programs and executing 32-bit
2118 boot time. When false, unconditionally disables IA32 emulation.
2141 idle=nomwait: Disable mwait for CPU C-states
2169 legacy only accept legacy-NaN binaries, if supported
2171 2008 only accept 2008-NaN binaries, if supported
2182 'relaxed' straps the emulator for both legacy-NaN and
2183 2008-NaN, whereas 'strict' enables legacy-NaN only on
2192 Ignore loglevel setting - this will print /all/
2259 Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
2260 "ima-sigv2" }
2261 Default: "ima-ng"
2299 stuff: Deploy RSB-fill mitigation when retpoline is
2304 Documentation/admin-guide/hw-vuln/indirect-target-selection.rst
2315 initcall_blacklist= [KNL] Do not execute a comma-separated list of
2316 initcall functions. Useful for debugging built-in
2331 initrd= [BOOT,EARLY] Specify the location of the initial ramdisk
2352 override in debugfs after boot.
2361 0 -- basic integrity auditing messages. (Default)
2362 1 -- additional integrity auditing messages.
2390 could harm performance of some high-throughput
2399 1 to 9 specify maximum depth of C-state.
2408 algorithms for p-state selection. There are two
2409 P-state selection algorithms provided by
2412 on whether or not the hardware managed P-states
2419 used along with the hardware-managed P-states (HWP)
2423 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2424 instead of acpi-cpufreq may disable platform features, such
2426 P-States information being indicated to OSPM and therefore
2429 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2442 Allow per-logical-CPU P-State performance control limits using
2445 Do not enable capacity-aware scheduling (CAS) on
2448 intremap= [X86-64,Intel-IOMMU,EARLY]
2453 BIOS x2APIC opt-out request will be ignored
2496 AMD Gart HW IOMMU-specific options:
2515 Do scatter-gather (SG) merging. Implies "force"
2519 Don't do scatter-gather (SG) merging.
2532 0 - Try to allocate a 32-bit DMA address first, before
2534 1 - Allocate directly from the full usable range,
2536 greater than 32-bit addressing.
2540 0 - Lazy mode.
2546 1 - Strict mode.
2549 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2551 legacy driver-specific options takes precedence.
2556 0 - Use IOMMU translation for DMA.
2557 1 - Bypass the IOMMU for DMA.
2558 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2560 io7= [HW] IO7 for Marvel-based Alpha systems
2575 See Documentation/admin-guide/nfs/nfsroot.rst.
2611 Enables support for pseudo-NMIs in the kernel. This
2616 [RISC-V,EARLY]
2618 as IPIs. Intended for system where IMSIC is trap-n-emulated,
2630 long-running IRQs in the system.
2642 [Deprecated - use cpusets instead]
2643 Format: [flag-list,]<cpu-list>
2676 "number of CPUs in system - 1".
2702 The format of <cpu-list> is described above.
2706 ivrs_ioapic [HW,X86-64]
2707 Provide an override to the IOAPIC-ID<->DEVICE-ID
2711 For example, to map IOAPIC-ID decimal 10 to
2717 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2720 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2724 ivrs_hpet [HW,X86-64]
2725 Provide an override to the HPET-ID<->DEVICE-ID
2729 For example, to map HPET-ID decimal 10 to
2735 * To map HPET-ID decimal 0 to PCI device 00:14.0
2738 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2742 ivrs_acpihid [HW,X86-64]
2743 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2747 For example, to map UART-HID:UID AMD0020:0 to
2753 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2756 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2770 Do not unregister boot console at start. This is only
2772 between unregistering the boot console and initializing
2780 the kernel for non-movable allocations. The requested
2790 subsystem. Note that allocations like PTEs-from-HighMem
2798 for non-movable allocations and remaining memory is used
2809 gdb or control-c on the dbgp connection. When
2810 not using this parameter you use sysrq-g to break into
2815 or a supported polling keyboard driver (non-usb).
2824 If the boot console provides the ability to read
2835 blank and the first boot console that implements
2844 "0" | "off" | "n" - kexec handover is disabled
2845 "1" | "on" | "y" - kexec handover is enabled
2851 ranges that can only be used for non-kernel
2862 parameter defines the size of additional per-node
2864 (in percents) of memory that was used during boot.
2867 Configure the RouterBoard 532 series on-chip
2870 kmemleak= [KNL,EARLY] Boot-time kmemleak enable/disable
2876 kprobe_event=[probe-list]
2877 [FTRACE] Add kprobe events and enable at boot time.
2878 The probe-list is a semicolon delimited list of probe
2887 Boot Parameter" section.
2908 execution by eliminating the write-protection faults
2935 virtualization on-demand when creating and destroying
2943 is that doing so may interfere with using out-of-tree
2969 [KVM] Controls the time period at which KVM zaps 4KiB pages
2970 back to huge pages. If the value is a non-zero N, KVM will
2975 kvm-amd.nested= [KVM,AMD] Control nested virtualization feature in
2978 kvm-amd.npt= [KVM,AMD] Control KVM's use of Nested Page Tables,
2979 a.k.a. Two-Dimensional Page Tables. Default is 1
2983 kvm-amd.ciphertext_hiding_asids=
2988 If ciphertext hiding is enabled, the joint SEV-ES and
2989 SEV-SNP ASID space is partitioned into separate SEV-ES
2990 and SEV-SNP ASID ranges, with the SEV-SNP range being
2991 [1..max_snp_asid] and the SEV-ES range being
2995 A non-zero value enables SEV-SNP ciphertext hiding and
2996 adjusts the ASID ranges for SEV-ES and SEV-SNP guests.
2997 KVM caps the number of SEV-SNP ASIDs at the maximum
2998 possible value, e.g. specifying -1u will assign all
2999 joint SEV-ES and SEV-SNP ASIDs to SEV-SNP. Note,
3000 assigning all joint ASIDs to SEV-SNP, i.e. configuring
3001 max_snp_asid == min_sev_asid-1, will effectively make
3002 SEV-ES unusable.
3004 kvm-arm.mode=
3010 nvhe: Standard nVHE-based mode, without support for
3017 nested: VHE-based mode with support for nested
3025 command-line.
3029 kvm-arm.vgic_v3_group0_trap=
3030 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-0
3033 kvm-arm.vgic_v3_group1_trap=
3034 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-1
3037 kvm-arm.vgic_v3_common_trap=
3041 kvm-arm.vgic_v4_enable=
3045 kvm-arm.wfe_trap_policy=
3054 kvm-arm.wfi_trap_policy=
3071 kvm-intel.ept= [KVM,Intel] Control KVM's use of Extended Page Tables,
3072 a.k.a. Two-Dimensional Page Tables. Default is 1
3076 kvm-intel.emulate_invalid_guest_state=
3078 state. Ignored if kvm-intel.enable_unrestricted_guest=1,
3084 kvm-intel.flexpriority=
3089 kvm-intel.nested=
3093 kvm-intel.unrestricted_guest=
3099 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
3100 CVE-2018-3620.
3111 kvm-intel.vpid= [KVM,Intel] Control KVM's use of Virtual Processor
3131 on - enable the interface for the mitigation
3147 boot. Hypervisors will issue a warning
3165 boot. Hypervisors will issue a warning
3177 boot. Hypervisors will issue a warning
3196 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
3202 lapic [X86-32,APIC,EARLY] Enable the local APIC even if BIOS
3206 value for LAPIC timer one-shot implementation. Default
3229 libata.force= [LIBATA] Force configurations. The format is a comma-
3241 first fan-out link behind PMP device. It does not
3255 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
3262 * rstonce: only attempt one reset during hot-unplug
3305 * external: Mark port as external (hotplug-capable).
3346 Set the time limit in jiffies for a lock
3359 Specify the number of self-propagating call_rcu()
3362 in progress at any given time. Defaults to 0,
3367 occasional long-duration lock hold time. Defaults
3378 Set the number of locking read-acquisition kthreads.
3383 Set the number of locking write-acquisition kthreads.
3386 Set time (s) after boot for CPU-hotplug testing.
3389 Set time (s) between CPU-hotplug operations, or
3390 zero to disable CPU-hotplug testing.
3393 Do periodic testing of real-time lock priority
3398 non-real-time spinlocks, due to their disabling
3399 of preemption. Note that non-realtime mutexes
3406 number of boosts per unit time remains roughly
3412 Set task-shuffle interval (jiffies). Shuffling
3413 tasks allows some CPUs to go into dyntick-idle
3417 Set time (s) after boot system shutdown. This
3418 is useful for hands-off automated testing.
3421 Time (s) between statistics printk()s.
3424 Time (s) to stutter testing, for example,
3437 Run the write-side locktorture kthreads at
3438 sched_set_fifo() real-time priority.
3456 7 (KERN_DEBUG) debug-level messages
3468 logo.nologo [FB] Disables display of the built-in Linux logo.
3471 kernel boot problems.
3486 an IEEE 1284-compliant printer is attached; if
3492 time-consuming boot-time autodetection (up to 250 ms per
3494 the correct value for your kernel, boot with normal
3512 Example: machtype=lemote-yeeloong-2f-7inch
3524 (loop.max_loop) unconditionally pre-created at init time. The default
3527 devices can be requested on-demand with the
3528 /dev/loop-control interface.
3530 mce= [X86-{32,64}]
3567 do not opt-in to Local MCE delivery. Use legacy method
3581 disable boot machine check logging.
3584 sets the time in us to wait for other CPUs on machine
3588 don't overwrite the bios-set CMCI threshold. This boot
3597 force-enable recoverable machine check code paths
3603 See Documentation/admin-guide/md.rst.
3610 Control mitigation for the Micro-architectural Data
3625 full - Enable MDS mitigation on vulnerable CPUs
3626 full,nosmt - Enable MDS mitigation and disable
3628 off - Unconditionally disable MDS mitigation
3630 On TAA-affected machines, mds=off can be prevented by
3639 For details see: Documentation/admin-guide/hw-vuln/mds.rst
3644 mem=nn[KMG] [KNL,BOOT,EARLY] Force usage of a specific amount
3654 [ARC,MICROBLAZE] - the limit applies only to low memory,
3657 [ARM64] - only limits memory covered by the linear
3665 Note that this only takes effects during boot time since
3666 in above case 3, memory may need be hot added after boot
3670 [ARM,MIPS,EARLY] - override the memory layout
3677 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
3684 per-device physically contiguous DMA buffers.
3692 See Documentation/admin-guide/mm/memory-hotplug.rst.
3717 Example: Exclude memory from 0x18690000-0x1869ffff
3731 memmap=<size>%<offset>-<oldtype>+<newtype>
3733 from <oldtype> to <newtype>. If "-<oldtype>" is left
3748 repeatable BIOS-originated corruption always
3792 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
3798 Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
3802 s2idle - Suspend-To-Idle
3803 shallow - Power-On Suspend or equivalent (if supported)
3804 deep - Suspend-To-RAM or equivalent (if supported)
3805 See Documentation/admin-guide/pm/sleep-states.rst.
3807 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
3817 base_rev=X - with <X> with format: <u32>
3831 0 - The attached screen is the 3.5" TFT
3832 1 - The attached screen is the 7" TFT
3833 2 - The VGA Shield is attached (1024x768)
3837 b - Enable backlight. The TFT backlight pin will be
3841 c - Enable the s3c camera interface.
3842 t - Reserved for enabling touchscreen support. The
3846 https://repo.or.cz/w/linux-2.6/mini2440.git
3851 arch-independent options, each of which is an
3852 aggregation of existing arch-specific options.
3882 ssbd=force-off [ARM64]
3896 have other ways of avoiding SMT-based attacks.
3910 supports attack-vector based controls as documented in
3911 Documentation/admin-guide/hw-vuln/attack_vector_controls.rst
3935 full - Enable mitigation on vulnerable CPUs
3937 full,nosmt - Enable mitigation and disable SMT on
3940 off - Unconditionally disable mitigation
3953 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3983 module_blacklist= [KNL] Do not load a comma-separated list of
3987 [MOUSE] Maximum time between finger touching and
4008 movable_node [KNL,EARLY] Boot-time switch to make hotplugable memory
4015 Format: <name>,<region-number>,<size>,<offset>
4018 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
4029 registers at boot time.
4050 at a time.
4057 something different and driver-specific.
4062 [NET] Specifies amount of time (in seconds) that
4097 [NFS] enable 64-bit inode numbers.
4098 If zero, the NFS client will fake up a 32-bit inode
4100 of returning the full 64-bit number.
4101 The default is to return 64-bit inode numbers.
4136 [NFS4] Specify an additional fixed unique ident-
4139 UUID that is generated at system install time.
4167 driver. A non-zero value sets the minimum interval
4172 server-to-server copies for which this server is
4184 server-to-server copy, knfsd temporarily mounts
4191 See Documentation/admin-guide/nfs/nfsroot.rst.
4193 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
4194 See Documentation/admin-guide/nfs/nfsroot.rst.
4197 See Documentation/admin-guide/nfs/nfsroot.rst.
4201 NMI stack-backtrace request.
4210 0 - turn hardlockup detector in nmi_watchdog off
4211 1 - turn hardlockup detector in nmi_watchdog on
4212 rNNN - configure the watchdog with raw perf event 0xNNN
4225 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
4229 no4lvl [RISCV,EARLY] Disable 4-level and 5-level paging modes.
4230 Forces kernel to use 3-level paging instead.
4232 no5lvl [X86-64,RISCV,EARLY] Disable 5-level paging mode. Forces
4233 kernel to use 4-level paging instead.
4264 nodsp [SH] Disable hardware DSP at boot time.
4268 no_entry_flush [PPC,EARLY] Don't flush the L1-D cache when entering the kernel.
4270 noexec32 [X86-64]
4271 This affects only 32-bit executables.
4272 noexec32=on: enable non-executable mappings (default)
4274 noexec32=off: disable non-executable mappings
4281 nofpu [MIPS,SH] Disable hardware FPU at boot time.
4285 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4287 legacy floating-point registers on task switch.
4316 nohz_full= [KNL,BOOT,SMP,ISOL]
4320 whenever possible. The boot CPU will be forced outside
4324 rcu_nocbs= boot parameter.
4332 nointremap [X86-64,Intel-IOMMU,EARLY] Do not enable interrupt
4334 [Deprecated - use intremap=off]
4340 noirqdebug [X86-32] Disables the code which attempts to detect and
4350 no-kvmapf [X86,KVM,EARLY] Disable paravirtualized asynchronous page
4353 no-kvmclock [X86,KVM,EARLY] Disable paravirtualized KVM clock driver
4355 nolapic [X86-32,APIC,EARLY] Do not enable or use the local APIC.
4357 nolapic_timer [X86-32,APIC,EARLY] Do not use the local APIC timer.
4359 nomce [X86-32] Disable Machine Check Exception
4361 nomfgpt [X86-32] Disable Multi-Function General Purpose
4367 not load if they could possibly displace the pre-
4370 perform display-mode changes or accelerated rendering.
4383 nopcid [X86-64,EARLY] Disable the PCID cpu feature.
4388 nopti [X86-64,EARLY]
4404 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
4410 no-scroll [VGA] Disables scrollback.
4411 This is required for the Braillex ib80-piezo Braille
4414 nosgx [X86-64,SGX,EARLY] Disables Intel SGX kernel support.
4434 nosoftlockup [KNL] Disable the soft-lockup detector.
4440 nospectre_bhb [ARM64,EARLY] Disable all mitigations for Spectre-BHB (branch
4453 no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,LOONGARCH,EARLY]
4454 Disable paravirtualized steal time accounting. steal time
4460 timer IRQ sources, i.e., the IO-APIC timer. This can
4465 [PPC,EARLY] Don't flush the L1-D cache after accessing user data.
4478 no-vmw-sched-clock
4483 soft-lockup and NMI watchdog (hard-lockup).
4487 nox2apic [X86-64,APIC,EARLY] Do not enable x2APIC mode.
4495 enabling legacy floating-point and sse state.
4517 n. So during boot up some boot time memory for per-cpu
4518 variables need be pre-allocated for later physical cpu
4545 soft-reserved memory partitioning.
4551 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
4553 This can be set from sysctl after boot.
4554 See Documentation/admin-guide/sysctl/vm.rst for details.
4557 See Documentation/core-api/debugging-via-ohci1394.rst for more
4572 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
4576 boundary - index of last SLC block on Flex-OneNAND.
4578 lock - Configure if Flex-OneNAND boundary should be locked.
4597 page_owner= [KNL,EARLY] Boot-time page_owner enabling option.
4603 page_poison= [KNL,EARLY] Boot-time parameter changing the state of
4631 See Documentation/admin-guide/tainted-kernels.rst for
4703 Set to non-zero to probe primary and secondary ISA
4709 Set to non-zero if a chip is present that snoops speed
4757 Set to non-zero to probe tertiary and further ISA
4773 Set to non-zero to probe QDI controllers. By default
4778 Set to non-zero to probe Winbond controllers. Use
4825 bios [X86-32] force use of PCI BIOS, don't access
4827 has a non-standard PCI host bridge.
4828 nobios [X86-32] disallow use of PCI BIOS, only direct
4834 data in IO port 0xCFC, both 32-bit).
4836 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
4837 the function, IO port 0xCFA, also 8-bit, sets
4839 through ports 0xC000-0xCFFF).
4843 enabled, this kernel boot option can be used to
4846 root domains (aka PCI segments, in ACPI-speak).
4853 enabled, this kernel boot option can be used to
4854 disable the use of MSI interrupts system-wide.
4855 noioapicquirk [APIC] Disable all boot interrupt quirks.
4856 Safety option to keep boot IRQs enabled. This
4858 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
4859 primary IO-APIC for bridges that cannot disable
4860 boot IRQs. This fixes a source of spurious IRQs
4863 boot IRQ equivalent of an IRQ that connects to
4864 a chipset where boot IRQs cannot be disabled.
4866 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
4890 F0000h-100000h range.
4895 assign-busses [X86] Always assign all PCI bus
4916 <linux-pci@vger.kernel.org>.
4920 a bug to <linux-pci@vger.kernel.org>.
4932 bfsort Sort PCI devices into breadth-first order.
4935 nobfsort Don't sort PCI devices into breadth-first order.
4937 tuning and use the BIOS-configured MPS defaults.
4947 configuration allows peer-to-peer DMA between
4950 that hot-added devices will work.
4965 A PCI-PCI bridge can be specified if resource
4971 for 4096-byte alignment.
4973 end-to-end CRC checking). Only effective if
5004 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
5035 bit-0 : ACS Source Validation
5036 bit-1 : ACS Translation Blocking
5037 bit-2 : ACS P2P Request Redirect
5038 bit-3 : ACS P2P Completion Redirect
5039 bit-4 : ACS Upstream Forwarding
5040 bit-5 : ACS P2P Egress Control
5041 bit-6 : ACS Direct Translated P2P
5051 Validation unchanged from whatever power-up
5061 is enabled, this kernel boot option can be used
5063 system-wide.
5077 dpc-native Use native PCIe service for DPC only. May
5094 Keep all power-domains already enabled by bootloader on,
5100 boot time.
5112 pirq= [SMP,APIC] Manual mp-table setup
5113 See Documentation/arch/x86/i386/IO-APIC.rst.
5117 See also Documentation/admin-guide/parport.rst.
5134 /sys/power/pm_async sysfs knob at boot time.
5136 resume of devices during system-wide power transitions.
5138 dependencies are not well-defined, or for debugging
5144 Enable suspend/resume debug messages during boot up.
5148 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
5157 { on | off | curr | res | no-curr | no-res }
5202 none - Limited to cond_resched() calls
5203 voluntary - Limited to cond_resched() and might_sleep() calls
5204 full - Any section that isn't explicitly preempt disabled
5208 lazy - Scheduler controlled. Similar to full but instead
5210 one HZ tick time to yield itself before the
5214 print-fatal-signals=
5220 coredump - etc.
5223 you might want to try "ulimit -i unlimited".
5235 or lockdep-detected issues (only if lock debug is on).
5243 Allows storing messages from non-panic CPUs into
5245 flushed to consoles by the panic-CPU on
5246 a best-effort basis.
5252 on - unlimited logging to /dev/kmsg from userspace
5253 off - logging to /dev/kmsg disabled
5254 ratelimit - ratelimit the logging
5257 printk.time= Show timing data prefixed to each printk message line
5265 - 'always': traditional behavior always allows mem overrides.
5266 - 'ptrace': only allow mem overrides for active ptracers.
5267 - 'never': never allow mem overrides.
5271 Limit processor to maximum C-state
5275 Ignore the _CST method to determine C-states,
5282 Param: "schedule" - profile schedule points.
5283 Param: "kvm" - profile VM exits.
5284 Param: <number> - step/bucket size as a power of 2 for
5285 statistical time based profiling.
5315 pti= [X86-64] Control Page Table Isolation of user and
5320 on - unconditionally enable
5321 off - unconditionally disable
5322 auto - kernel detects whether your CPU model is
5328 [KNL] Number of legacy pty's. Overwrites compiled-in
5340 See Documentation/admin-guide/md.rst.
5343 See Documentation/admin-guide/blockdev/ramdisk.rst.
5362 cross-syscall address exposures. This is only
5368 ras=option[,option,...] [KNL] RAS-specific options
5374 rcu_nocbs[=cpu-list]
5379 enable the no-callback CPU mode, which prevents
5384 "p" for RCU-preempt, "s" for RCU-sched, and "g"
5388 and real-time workloads. It can also improve
5392 list of CPUs is set to no-callback mode from boot.
5396 no-callback mode from boot but the mode may be
5407 This improves the real-time response for the
5418 Do only a one-line RCU CPU stall warning when
5419 there is an ongoing too-long CSD-lock wait.
5425 If triggered before the RCU grace-period machinery
5430 out at early boot. This is used for diagnostic
5435 RCU grace-period cleanup.
5439 RCU grace-period initialization.
5443 RCU grace-period pre-initialization, that is,
5444 the propagation of recent CPU-hotplug changes up
5448 Set delay from grace-period initialization to
5461 soliciting quiescent-state help from
5472 rcutree.kthread_prio= [KNL,BOOT]
5473 Set the SCHED_FIFO priority of the RCU per-CPU
5476 and for the RCU grace-period kthreads (rcu_bh,
5478 set, valid values are 1-99 and the default is 1
5479 (the least-favored priority). Otherwise, when
5480 RCU_BOOST is not set, valid values are 0-99 and
5481 the default is zero (non-realtime operation).
5486 On callback-offloaded (rcu_nocbs) CPUs,
5489 use of the ->nocb_bypass list. However, in the
5490 common non-flooded case, RCU queues directly to
5491 the main ->cblist in order to avoid the extra
5492 overhead of the ->nocb_bypass list and its lock.
5494 a single jiffy, RCU pre-queues the callbacks into
5495 the ->nocb_bypass queue. The definition of "too
5496 many" is supplied by this kernel boot parameter.
5499 On callback-offloaded (rcu_nocbs) CPUs, avoid
5512 batch limiting is re-enabled.
5516 RCU's force-quiescent-state scan will aggressively
5520 on rcutree.qhimark at boot time and to zero to
5524 Set the page-cache refill delay (in milliseconds)
5525 in response to low-memory conditions. The range
5529 Set the shift-right count to use to compute
5530 the callback-invocation batch limit bl from
5537 Please note that this callback-invocation batch
5538 limit applies only to non-offloaded callback
5547 cache-to-cache transfer latencies.
5553 and for NUMA systems with large remote-access
5569 the wakeup overhead on the global grace-period
5571 each group's NOCB grace-period kthread.
5574 Cause the grace-period kthread to get an extra
5576 it should at force-quiescent-state time.
5581 Limit the time spend invoking a batch of RCU
5589 this specifies an rcu_read_unlock()-time delay
5593 of RCU-protected pointers after the relevant
5603 per-CPU rcuc kthreads. Defaults to a non-zero
5608 this kernel boot parameter, forcibly setting it
5626 or pass a boot parameter "rcutree.rcu_normal_wake_from_gp=1"
5629 disabled by the boot parameter passing 0.
5633 grace-period primitives such as call_rcu().
5644 grace-period primitives.
5647 Set test-start holdoff period. The purpose of
5649 test until boot completes in order to avoid
5665 Test the double-argument variant of kfree_rcu().
5667 rcuscale.kfree_rcu_test_single, both the single-
5668 and double-argument variants are tested.
5671 Test the single-argument variant of kfree_rcu().
5673 rcuscale.kfree_rcu_test_double, both the single-
5674 and double-argument variants are tested.
5687 Set the minimum test run time in seconds. This
5688 does not affect the data-collection interval,
5693 Set number of RCU readers. The value -1 selects
5695 "n" less than -1 selects N-n+1, where N is again
5696 the number of CPUs. For example, -2 selects N
5697 (the number of CPUs), -3 selects N+1, and so on.
5698 A value of "n" less than or equal to -N selects
5711 complete. This is useful for hands-off automated
5718 Write-side holdoff between grace periods,
5723 Additional write-side holdoff between grace
5732 Set holdoff time within force_quiescent_state bursts
5736 Set wait time between force_quiescent_state bursts
5741 for RCU grace-period forward-progress testing
5748 Specify the fraction of a CPU-stall-warning
5749 period to do tight-loop forward-progress testing.
5753 forward-progress tests.
5757 need_resched() during tight-loop forward-progress
5761 Use conditional/asynchronous update-side
5762 normal-grace-period primitives, if available.
5765 Use conditional/asynchronous update-side
5766 expedited-grace-period primitives, if available.
5769 Use conditional/asynchronous update-side
5770 normal-grace-period primitives that also take
5775 Use conditional/asynchronous update-side
5776 expedited-grace-period primitives that also take
5800 Use expedited update-side primitives, if available.
5803 Use normal (non-expedited) asynchronous
5804 update-side primitives, if available.
5807 Use polled update-side normal-grace-period
5811 Use polled update-side expedited-grace-period
5815 Use polled update-side normal-grace-period
5820 Use polled update-side expedited-grace-period
5844 Use normal (non-expedited) synchronous
5845 update-side primitives, if available. If all
5849 they are all non-zero.
5852 Enable grace-period wrap lag testing. Setting
5857 Set the value for grace-period wrap lag during
5865 testing in minutes. This is the total time for
5871 within each cycle, in minutes. During this time,
5872 the grace-period wrap lag will be set to the
5882 Leak an RCU-protected pointer out of the reader.
5897 Set number of RCU callback-offload togglers.
5902 callback-offload toggling attempts.
5905 Set number of RCU readers. The value -1 selects
5906 N-1, where N is the number of CPUs. A value
5907 "n" less than -1 selects N-n-2, where N is again
5908 the number of CPUs. For example, -2 selects N
5909 (the number of CPUs), -3 selects N+1, and so on.
5912 Enable debug-object double-call_rcu() testing.
5915 Set time (s) after boot for CPU-hotplug testing.
5918 Set time (jiffies) between CPU-hotplug operations,
5919 or zero to disable CPU-hotplug testing.
5923 by a high-priority FIFO real-time task. Set to
5926 are online at a given point in time. Races with
5932 second) between preemptions by a high-priority
5933 FIFO real-time task. This delay is mediated
5938 The number of times in a given read-then-exit
5939 episode that a set of read-then-exit kthreads
5944 read-then-exit testing episodes.
5949 are entered from low-order bit up, and are
5951 0x1 bit is normal readers, 0x2 NMI-safe readers,
5952 and 0x4 light-weight readers.
5955 Set task-shuffle interval (s). Shuffling tasks
5956 allows some CPUs to go into dyntick-idle mode
5960 Set time (s) after boot system shutdown. This
5961 is useful for hands-off automated testing.
5970 any other stall-related activity. Note that
5976 in scheduling-while-atomic splats.
5982 Time to wait (s) after boot before inducing stall.
5995 grace-period kthread to test RCU CPU stall
6001 Time (s) between statistics printk()s.
6004 Time (s) to stutter testing, for example, specifying
6018 Holdoff time (s) from start of test to the start
6019 of RCU priority-boost testing. Defaults to zero,
6026 Test RCU's dyntick-idle handling. See also the
6051 during early boot, that is, during the time
6081 Use expedited grace-period primitives, for
6085 real-time latency, and degrade energy efficiency.
6089 Use only normal grace-period primitives,
6092 real-time latency, CPU utilization, and
6094 increased grace-period latency. This parameter
6099 Once boot has completed (that is, after
6101 only normal grace-period primitives. No effect
6105 this kernel boot parameter, forcibly setting
6107 post-boot attempt at an expedited RCU grace
6108 period to instead use normal non-expedited
6109 grace-period processing.
6117 set to the default value of -1.
6120 Set the minimum number of callback-queuing-time
6121 lock-contention events per jiffy required to
6122 cause the RCU Tasks flavors to switch to per-CPU
6125 the default value of -1.
6130 of -1 allows this to be automatically (and
6135 Set time in jiffies during which RCU tasks will
6138 number avoids disturbing real-time workloads,
6143 cancel laziness on that CPU. Use -1 to disable
6153 only printed prior to the stall-warning message
6160 Multiplier for time interval between successive
6193 Run the RCU early boot self tests
6201 force - Override the decision by the kernel to hide the
6240 There are some built-in platform specific "quirks"
6241 - you may see: "reboot: <name> series board detected.
6245 built-in quirk table, and use the generic default
6274 there may be boot problems on some systems.
6278 Set test-start holdoff period. The purpose of
6280 test until boot completes in order to avoid
6293 but the default has already reduced the per-pass
6298 Set number of readers. The default value of -1
6307 Set the read-side critical-section duration,
6311 Specify the read-protection implementation to test.
6337 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
6355 was from a previous boot, the new reservation will be at a
6359 boot, as there may be cases where the memory will not be
6367 reservetop= [X86-32,EARLY]
6384 See Documentation/power/swsusp-and-swap-files.rst
6393 retain_initrd [RAM] Keep initrd memory after extraction. After boot, it will
6400 AMD-based UNRET and IBPB mitigations alone do not stop
6402 sibling threads. For that reason, STIBP is used on pro-
6406 off - no mitigation
6407 auto - automatically select a migitation
6408 auto,nosmt - automatically select a mitigation,
6412 ibpb - On AMD, mitigate short speculation
6417 ibpb,nosmt - Like "ibpb" above but will disable SMT
6421 unret - Force enable untrained return thunks,
6422 only effective on AMD f15h-f17h based
6424 unret,nosmt - Like unret, but will disable SMT when STIBP
6429 time according to the CPU.
6456 ro [KNL] Mount root device read-only on boot
6459 on Mark read-only kernel memory as read-only (default).
6460 off Leave read-only kernel memory writable for debugging.
6461 noalias Mark read-only kernel memory as read-only but retain
6469 debug-uart get routed to the D+ and D- pins of the usb
6475 block/early-lookup.c for details.
6494 rootwait= [KNL] Maximum time (in seconds) to wait for root device
6508 rw [KNL] Mount root device read-write on boot
6537 solution to mutex-based priority inversion.
6567 to 10 seconds for built-in smp_call_function()
6574 that requesting even small non-zero numbers of
6581 The default of -1 specifies a number of kthreads
6586 test before initiating CPU-hotplug operations.
6590 CPU-hotplug operations. Specifying zero (which
6591 is the default) disables CPU-hotplug operations.
6597 Non-zero values are useful for automated tests.
6620 "wait" parameter. A value of -1 selects the
6621 default if all other weights are -1. However,
6623 value of -1 will instead select a weight of zero.
6628 non-zero "wait" parameter. See weight_single.
6641 non-zero "wait" parameter. See weight_single
6653 non-zero "wait" parameter. See weight_single
6664 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
6665 1 -- enable.
6670 enable at boot. This has been deprecated by the
6673 selinux= [SELINUX] Disable or enable SELinux at boot time.
6676 0 -- disable.
6677 1 -- enable.
6680 serialnumber [BUGS=X86-32]
6682 sev=option[,option...] [X86-64]
6688 Do not enable SEV-SNP (applies to host/hypervisor
6691 SEV-SNP guests.
6699 to set it to "all" by meaning -- no limit here.
6711 Documentation/admin-guide/mm/slab.rst.
6722 Documentation/admin-guide/mm/slab.rst.
6738 Documentation/admin-guide/mm/slab.rst.
6744 Documentation/admin-guide/mm/slab.rst.
6759 Documentation/admin-guide/mm/slab.rst.
6778 Specify the period of time in milliseconds
6783 of time. Defaults to 5,000 milliseconds, and
6786 using the csdlock_debug- kernel parameter.
6791 system. By default, let CSD-lock acquisition
6793 for this value provides a 5-minute timeout.
6795 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
6796 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
6797 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
6798 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
6799 smsc-ircc2.ircc_irq= [HW] IRQ line
6800 smsc-ircc2.ircc_dma= [HW] DMA channel
6801 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
6811 Default: -1 (no limit)
6814 [KNL] Should the soft-lockup detector generate panics.
6817 A value of 1 instructs the soft-lockup detector
6818 to panic the machine when a soft-lockup occurs. It is
6821 respective build-time switch to that functionality.
6824 [KNL] Should the soft-lockup detector generate
6829 See Documentation/admin-guide/laptops/sonypi.rst
6836 on - (default) Enable the HW or SW mitigation as
6839 vmexit - On systems which don't have the HW mitigation
6842 protected from VM-originated BHI attacks, but
6844 off - Disable the mitigation.
6851 on - unconditionally enable, implies
6853 off - unconditionally disable, implies
6855 auto - kernel detects whether your CPU model is
6859 mitigation method at run time according to the
6874 retpoline - replace indirect branches
6875 retpoline,generic - Retpolines
6876 retpoline,lfence - LFENCE; indirect branch
6877 retpoline,amd - alias for retpoline,lfence
6878 eibrs - Enhanced/Auto IBRS
6879 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
6880 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
6881 ibrs - use IBRS to protect kernel
6891 on - Unconditionally enable mitigations. Is
6894 off - Unconditionally disable mitigations. Is
6897 prctl - Indirect branch speculation is enabled,
6903 - Like "prctl" above, but only STIBP is
6909 - Same as "prctl" above, but all seccomp
6914 - Like "seccomp" above, but only STIBP is
6919 auto - Kernel selects the mitigation depending on
6930 off - Disable mitigation
6931 microcode - Enable microcode mitigation only
6932 safe-ret - Enable sw-only safe RET mitigation (default)
6933 ibpb - Enable mitigation by issuing IBPB on
6935 ibpb-vmexit - Issue IBPB only on VMEXIT
6936 (cloud-specific mitigation)
6961 on - Unconditionally disable Speculative Store Bypass
6962 off - Unconditionally enable Speculative Store Bypass
6963 auto - Kernel detects whether the CPU model contains an
6969 prctl - Control Speculative Store Bypass per thread
6973 seccomp - Same as "prctl" above, but all seccomp threads
6981 on,auto - On Power8 and Power9 insert a store-forwarding
6985 off - No action.
6999 off - not enabled
7001 warn - the kernel will emit rate-limited warnings
7009 fatal - the kernel will send SIGBUS to applications
7014 ratelimit:N -
7034 Certain CPUs are vulnerable to an MDS-like
7054 This kernel-boot parameter defaults to 128,
7055 but takes effect only when the low-order four
7057 (decide at boot).
7065 1: At init_srcu_struct() time.
7067 3: Decide at boot time (default).
7072 instead of the compile-time CONFIG_NR_CPUS.
7076 grace-period sequence counter wrap for the
7077 srcu_data structure's ->srcu_gp_seq_needed field.
7092 Specifies the number of no-delay instances
7099 Specifies the per-grace-period phase, number of
7100 non-sleeping polls of readers. Beyond this limit,
7106 Specifies number of microseconds of non-sleeping
7107 delay between each non-sleeping poll of readers.
7110 Specifies the number of update-side contention
7115 set for contention-based conversions to occur.
7125 force-on: Unconditionally enable mitigation for
7127 force-off: Unconditionally disable mitigation for
7149 stack traces. Pools are allocated on-demand up to this
7153 Enabled the stack tracer on boot up.
7155 stacktrace_filter=[function-list]
7157 will trace at boot up. function-list is a comma-separated
7159 time by the stack_trace_filter file in the debugfs
7165 Set the STI (builtin display/keyboard on the HP-PARISC
7167 as the initial boot-console.
7227 to global on non-NUMA machines)
7252 <int> -- Number of I/O TLB slabs
7253 <int> -- Second integer after comma. Number of swiotlb
7256 force -- force using of bounce buffers even if they
7258 noforce -- Never use bounce buffers (for debugging)
7273 Ignore sysrq setting - this boot parameter will
7281 cache size. See Documentation/networking/ip-sysctl.rst
7288 Specify "mem" (for Suspend-to-RAM) or "standby" (for
7293 wakeup-capable RTC alarm.
7299 -1: disable all active trip points in all thermal zones
7303 -1: disable all critical trip points in all thermal zones
7310 -1: disable all passive trip points
7316 <deci-seconds>: poll all this frequency
7320 Format: <size>[KMG],<size>[KMG]:<state>;<size>[KMG]-<size>[KMG]:<state>
7325 See Documentation/admin-guide/mm/transhuge.rst for more
7333 Format: <size>[KMG],<size>[KMG]:<policy>;<size>[KMG]-<size>[KMG]:<policy>
7339 See Documentation/admin-guide/mm/transhuge.rst for more
7351 Prevent the CPU-hotplug component of torturing
7355 Dump the ftrace buffer at torture-test shutdown,
7359 with rotating-rust storage.
7364 disables verbose-printk() sleeping.
7367 Duration of each verbose-printk() sleep in jiffies.
7379 Maximum time in milliseconds to retry sending a message
7388 Specify that at suspend time, the tpm driver
7400 https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
7404 tracing ring buffer. This is useful for early boot up
7427 printing of events during boot up, as user space may
7431 to console at the late_initcall_sync() time frame.
7437 at boot up.
7438 local - Use the per CPU time stamp counter
7442 global - Event time stamps are synchronized across
7445 counter - Simple counting of events (1, 2, ..)
7449 uptime - Use jiffies as the time stamp.
7450 perf - Use the same clock that perf uses.
7451 mono - Use ktime_get_mono_fast_ns() for time stamps.
7452 mono_raw - Use ktime_get_raw_fast_ns() for time
7454 boot - Use ktime_get_boot_fast_ns() for time stamps.
7458 trace_event=[event-list]
7460 to facilitate early boot debugging. The event-list is a
7461 comma-separated list of trace events to enable. See
7472 trace_instance=[instance-info]
7473 [FTRACE] Create a ring buffer instance early in boot up.
7478 Events can be enabled at the time the instance is created
7497 traceoff - Have the tracing instance tracing disabled after it is created.
7498 traceprintk - Have trace_printk() write into this trace instance
7518 This will reserve 12 megabytes at boot up with a 4096 byte alignment
7520 memory may not be the same location each time, which will not preserve
7528 it is recommend to disable tracing so that events from a previous boot do not
7529 mix with events of the current boot (unless you are debugging a random crash
7530 at boot up).
7536 can force a memory reset on boot which will clear any trace that was stored.
7545 trace_options=[option-list]
7546 [FTRACE] Enable or disable tracer options at boot.
7547 The option-list is a comma delimited list of options
7561 trace_trigger=[trigger-list]
7582 during the boot process. Since the trace buffer has a
7584 disable tracing after the boot is finished, otherwise
7587 the end of the boot process.
7599 This option can also be set at run time via the sysctl
7607 See Documentation/admin-guide/mm/transhuge.rst
7614 See Documentation/admin-guide/mm/transhuge.rst
7621 See Documentation/admin-guide/mm/transhuge.rst
7629 - "tpm"
7630 - "tee"
7631 - "caam"
7632 - "dcp"
7642 - "kernel"
7643 - the same value as trusted.source: "tpm" or "tee"
7644 - "default"
7667 off - disable the mitigation
7668 on - enable the mitigation (default)
7669 user - mitigate only user/kernel transitions
7670 vm - mitigate only guest/host transitions
7678 high-resolution timer mode on older hardware, and in
7681 Used to run time disable IRQ_TIME_ACCOUNTING on any
7714 on - Enable TSX on the system. Although there are
7717 several previous speculation-related CVEs, and
7721 off - Disable TSX on the system. (Note that this
7729 auto - Disable TSX if X86_BUG_TAA is present,
7734 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7740 Similar to Micro-architectural Data Sampling (MDS)
7755 full - Enable TAA mitigation on vulnerable CPUs
7758 full,nosmt - Enable TAA mitigation and disable SMT on
7761 vulnerable to cross-thread TAA attacks.
7762 off - Unconditionally disable TAA mitigation
7764 On MDS-affected machines, tsx_async_abort=off can be
7776 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7782 See also Documentation/input/devices/joystick-parport.rst
7784 udbg-immortal [PPC] When debugging early kernel crashes that
7786 console driver takes over, this boot options might
7790 Set number of hash buckets for UDP/UDP-Lite connections
7792 uhci-hcd.ignore_oc=
7794 Some badly-designed motherboards generate lots of
7819 unwind_debug [X86-64,EARLY]
7827 (default -1 = authorized (same as 1),
7832 [USB] The autosuspend time delay (in seconds) used
7833 for newly-detected USB devices (default 2). This
7834 is the time required before an idle device will be
7861 [USB] Specifies timeout for the initial 64-byte
7868 [USB] A list of quirk entries to augment the built-in
7871 VendorID:ProductID:Flags. The IDs are 4-digit hex
7873 will change the built-in quirk; setting it if it is
7878 a 255-byte read);
7882 Set-Interface requests);
7901 (bInterval-1).
7939 usb-storage.delay_use=
7946 usb-storage.quirks=
7948 override the built-in unusual_devs list. List
7951 and Product ID values (4-digit hex numbers) and
7953 to a common usb-storage quirk flag as follows:
7967 240 sectors at a time, uas only);
7979 than 64 sectors = 32 KB at a time,
7995 medium is write-protected).
8004 1 - undefined instruction events
8005 2 - system calls
8006 4 - invalid data aborts
8007 8 - SIGSEGV faults
8008 16 - SIGBUS faults
8017 vdso32= [X86] Control the 32-bit vDSO
8018 vdso32=1: enable 32-bit VDSO
8019 vdso32=0 or vdso32=2: disable 32-bit VDSO
8029 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
8060 vga= [BOOT,X86-32] Select a particular video mode
8061 See Documentation/arch/x86/boot.rst and
8062 Documentation/admin-guide/svga.rst.
8064 This is actually a boot loader parameter; the value is
8068 May slow down system boot speed, especially when
8076 P Enable page structure init time poisoning
8077 - Disable all of the above options
8079 vmalloc=nn[KMG] [KNL,BOOT,EARLY] Forces the vmalloc area to have an
8103 hypervisor to a guest via speculative side-channels.
8105 off - disable the mitigation
8106 ibpb - use Indirect Branch Prediction Barrier
8108 force - force vulnerability detection even on
8111 vsyscall= [X86-64,EARLY]
8114 code). Most statically-linked binaries and older
8138 see vga-softcursor.rst. Default: 2 = underline.
8143 This is a 16-member array composed of values
8144 ranging from 0-255.
8149 This is a 16-member array composed of values
8150 ranging from 0-255.
8155 This is a 16-member array composed of values
8156 ranging from 0-255.
8161 Set system-wide default UTF-8 mode for all tty's.
8162 Default is 1, i.e. UTF-8 mode is enabled for all
8167 Format=<-1|0|1>
8168 Set system-wide default for whether a cursor
8169 is shown on new VTs. Default is -1,
8174 vt.italic= [VT] Default color for italic text; 0-15.
8177 vt.underline= [VT] Default color for underlined text; 0-15.
8181 see Documentation/watchdog/watchdog-parameters.rst
8182 or other driver-specific files in the
8196 Format: <cpu-list>
8217 Per-cpu work items which run for longer than this
8220 them from noticeably delaying other per-cpu work
8238 Per-cpu workqueues are generally preferred because
8240 locality; unfortunately, per-cpu workqueues tend to
8243 Enabling this makes the per-cpu workqueues which
8257 Documentation/core-api/workqueue.rst.
8259 This can be changed after boot by writing to the
8270 forces round-robin CPU selection to flush out
8278 on - Enable writecombine, use WUC for ioremap_wc()
8279 off - Disable writecombine, use SUC for ioremap_wc()
8281 x2apic_phys [X86-64,APIC,EARLY] Use x2apic physical mode instead of
8285 xen_512gb_limit [KNL,X86-64,XEN]
8295 ide-disks -- unplug primary master IDE devices
8296 aux-ide-disks -- unplug non-primary-master IDE devices
8297 nics -- unplug network devices
8298 all -- unplug all emulated devices (NICs and IDE disks)
8299 unnecessary -- unplugging emulated devices is
8302 never -- do not unplug even if version check succeeds
8316 Select whether to always use non-faulting (safe) MSR
8336 xen_timer_slop= [X86-64,XEN,EARLY]
8344 The time (in seconds) to wait before giving up to boot
8355 After which time (jiffies) the event handling loop
8361 preferred over the 2-level event handling, as it is
8378 xive.store-eoi=off [PPC]
8384 xhci-hcd.quirks [USB,KNL]
8393 early Call xmon as early as possible on boot; xmon