Lines Matching +full:auto +full:- +full:boot
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]
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
585 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
604 inclusive. See arch/mips/include/asm/pgtable-bits.h
614 - foo isn't auto-mounted if you mount all cgroups in
616 - foo isn't visible as an individually mountable
618 - if foo is an optional feature then the feature is
624 Specifying "pressure" disables per-cgroup pressure
641 semi-legacy software can check this file to decide
650 nosocket -- Disable socket memory accounting.
651 nokmem -- Disable kernel memory accounting.
652 nobpf -- Disable BPF memory accounting.
657 0 -- check protection applied by kernel (includes
659 1 -- check protection requested by application.
671 numbers X. Note the Linux-specific bits are not necessarily
672 stable over kernel options, but the vendor-specific
692 force such clocks to be always-on nor does it reserve
696 information, see Documentation/driver-api/clk.rst.
698 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
715 [X86-32] pit,hpet,tsc;
722 [X86-64] hpet,tsc
728 architected timer so that code using WFE-based polling
742 clocksource-wdtest.holdoff= [KNL]
748 cma=nn[MG]@[start[MG][-end[MG]]]
759 Sets the size of kernel per-numa memory area for
761 per-numa CMA altogether. And If this option is not
763 With per-numa CMA enabled, DMA users on node nid will
790 com20020= [HW,NET] ARCnet - COM20020 chipset
794 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
798 ARCnet - COM90xx chipset (memory-mapped buffers)
811 This leads to a much faster boot time when a 3270
827 See Documentation/admin-guide/serial-console.rst for more
842 $ ls -d /sys/bus/serial-base/devices/*:*.*/tty/*
843 /sys/bus/serial-base/devices/00:04:0.0/tty/ttyS0
856 Start an early, polled-mode console on the 8250/16550
859 MMIO inter-register address stride is either 8-bit
860 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
864 the h/w is not re-initialized.
891 syscall, or to executing "dmesg -S --raw" or to reading
908 1: enable debugging at boot time
915 disable the cpuidle sub-system
921 disable the cpufreq sub-system
929 [X86,EARLY] Delay for N microsec between assert and de-assert
931 on every CPU online, such as boot, and resume from suspend.
950 like Hyper-V, PowerPC (fadump) and AMD SEV-SNP.
958 [KNL, X86-64, ARM64, RISCV, LoongArch] Select a region
961 See Documentation/admin-guide/kdump/kdump.rst for further details.
966 start-[end] where start and end are both
968 Documentation/admin-guide/kdump/kdump.rst for an example.
971 [KNL, X86-64, ARM64, RISCV, LoongArch] range could be
979 [KNL, X86-64, ARM64, RISCV, LoongArch] range under 4G.
985 for 32-bit devices won't run out. Kernel would try to allocate
988 --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
989 --> arm64: 128MiB
990 --> riscv: 128MiB
991 --> loongarch: 128MiB
1021 [KNL] Disable crypto self-tests
1029 csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
1044 See also Documentation/input/devices/joystick-parport.rst
1050 boot sequence. If enabled, we use a weak hash instead
1057 [KNL] verbose locking self-tests
1060 self-tests.
1062 (no extra messages), setting it to -1 (all bits set)
1063 will print _a_lot_ more information - normally only
1089 enables the feature at boot time. By default, it is
1098 Format: { on, no-mount, off }
1100 no-mount:
1105 get a -EPERM as result when trying to register files
1109 Default value is set in build-time with a kernel configuration.
1121 Documentation/admin-guide/mm/hugetlbpage.rst.
1135 delayacct [KNL] Enable per-task delay accounting
1217 this option disables the debugging code at boot.
1221 entries for DMA-API debugging code. One entry is
1222 required per DMA-API allocation. Use this if the
1223 DMA-API debugging code disables itself because the
1227 With this option the DMA-API debugging driver
1228 filter feature can be enabled at boot time. Just
1251 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
1276 Control how the dt_cpu_ftrs device-tree binding is
1286 what data is available or for reverse-engineering.
1290 Enable debug messages at boot time. See
1291 Documentation/admin-guide/dynamic-debug-howto.rst
1302 determined by stdout-path property in device tree's
1307 Start an early, polled-mode console on a Cadence
1318 Start an early, polled-mode console on the 8250/16550
1320 MMIO inter-register address stride is either 8-bit
1321 (mmio) or 32-bit (mmio32 or mmio32be).
1331 Start an early, polled-mode console on a pl011 serial
1335 the driver will use only 32-bit accessors to read/write
1344 Start an early, polled-mode console on a meson serial
1350 Start an early, polled-mode console on an msm serial
1356 Start an early, polled-mode console on an msm serial
1362 Start an early, polled-mode console on a serial port
1368 Start an early, polled-mode console on a serial port
1374 Use RISC-V SBI (Supervisor Binary Interface) for early
1392 Start an early, polled-mode console on a lantiq serial
1406 Start an early, polled-mode, output-only console on the
1411 Start an early, polled-mode console on the
1417 Start an early, polled-mode console on a Qualcomm
1425 coherent non-x86 systems that use system memory for
1503 PCI bridges while in the EFI boot stub.
1505 boot stub, as chunking can cause problems with some
1516 on all PCI bridges while in the EFI boot stub
1528 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1538 the boot argument: earlyprintk=vga
1542 very early in the boot process. For early debugging
1545 elanfreq= [X86-32]
1553 See Documentation/admin-guide/kdump/kdump.rst for details.
1569 0 -- permissive (log only, no denials).
1570 1 -- enforcing (deny and log).
1589 stages so cover more early boot allocations.
1592 memory initialization is disabled) so the boot process
1603 See also Documentation/fault-injection/.
1607 See Documentation/admin-guide/sysctl/net.rst for
1611 See Documentation/admin-guide/blockdev/floppy.rst.
1613 forcepae [X86-32]
1620 fred= [X86-64]
1629 boot debugging.
1632 [FTRACE] On boot up, a snapshot will be taken of the
1636 boot up that is likely to be overridden by user space
1646 a snapshot at the end of boot up.
1671 ftrace_filter=[function-list]
1673 tracer at boot up. function-list is a comma-separated
1678 ftrace_notrace=[function-list]
1680 function-list. This list can be changed at run time
1684 ftrace_graph_filter=[function-list]
1686 by the function graph tracer at boot up.
1687 function-list is a comma-separated list of functions
1691 ftrace_graph_notrace=[function-list]
1693 function-list. This list is a comma-separated list of
1708 (suppliers first, then consumers), supplier boot state
1713 off -- Don't create device links from firmware info.
1714 permissive -- Create device links from firmware info
1715 but use it only for ordering boot state clean
1717 on -- Create device links from firmware info and use it
1719 rpm -- Like "on", but also use to order runtime PM.
1732 strict -- Default. Continue waiting on consumers to
1734 timeout -- Give up waiting on consumers and call
1744 See also Documentation/input/devices/joystick-parport.rst
1748 gart_fix_e820= [X86-64,EARLY] disable the fix e820 for K8 GART
1774 gcov_persist= [GCOV] When non-zero (default), profiling data for
1784 gpio-mockup.gpio_mockup_ranges
1787 gpio-mockup.gpio_mockup_named_lines
1815 hardening is enabled for this boot. Hardened
1819 against bounds-checking flaws in the kernel's
1827 [KNL] Should the hard-lockup detector generate
1840 Format: { auto | always | never }
1841 Default: auto
1843 auto - Hash pointers unless slab_debug is enabled.
1844 always - Always hash pointers (even if slab_debug is
1846 never - Never hash pointers. This option should only
1848 not use on production kernels. The boot
1852 hashdist= [KNL,NUMA] Large hashes allocated during boot
1854 for 64-bit NUMA, off otherwise.
1862 corresponding firmware-first mode error processing
1867 present during boot.
1872 during restoration read-only).
1892 highmem=nn[KMG] [KNL,BOOT,EARLY] forces the highmem zone to have an exact
1916 hpet= [X86-32,HPET] option to control HPET usage
1927 hugepages= [HW,EARLY] Number of HugeTLB pages to allocate at boot.
1933 number of pages to allocate per-node can be specified.
1934 See also Documentation/admin-guide/mm/hugetlbpage.rst.
1941 allocate huge pages of a specific size at boot. The
1945 Documentation/admin-guide/mm/hugetlbpage.rst.
1950 allocate hugepages during boot. This option can be
1955 Note that this parameter only applies to non-gigantic huge pages.
1965 boot-time allocation of gigantic hugepages is skipped.
2000 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
2001 option. The value selected by this boot parameter can
2006 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
2028 Set device-properties for ACPI-enumerated I2C-attached
2029 touchscreen, to e.g. fix coordinates of upside-down
2037 Omit "=<val>" entirely Set a boolean device-property
2038 Unsigned number Set a u32 device-property
2039 Anything else Set a string device-property
2042 i2c_touchscreen_props=GDIX1001:touchscreen-inverted-x:
2043 touchscreen-inverted-y
2045 i2c_touchscreen_props=MSSL1680:touchscreen-size-x=1920:
2046 touchscreen-size-y=1080:touchscreen-inverted-y:
2047 firmware-name=gsl1680-vendor-model.fw:silead,home-button
2052 (disabled by default, and as a pre-condition
2054 i8042.direct [HW] Put keyboard port into non-translated mode
2068 suspend-to-ram transitions, only during s2r
2092 -1 -- never invert brightness
2093 0 -- machine default
2094 1 -- force brightness inversion
2096 ia32_emulation= [X86-64]
2098 When true, allows loading 32-bit programs and executing 32-bit
2100 boot time. When false, unconditionally disables IA32 emulation.
2123 idle=nomwait: Disable mwait for CPU C-states
2151 legacy only accept legacy-NaN binaries, if supported
2153 2008 only accept 2008-NaN binaries, if supported
2164 'relaxed' straps the emulator for both legacy-NaN and
2165 2008-NaN, whereas 'strict' enables legacy-NaN only on
2174 Ignore loglevel setting - this will print /all/
2241 Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
2242 "ima-sigv2" }
2243 Default: "ima-ng"
2281 stuff: Deploy RSB-fill mitigation when retpoline is
2286 Documentation/admin-guide/hw-vuln/indirect-target-selection.rst
2297 initcall_blacklist= [KNL] Do not execute a comma-separated list of
2298 initcall functions. Useful for debugging built-in
2313 initrd= [BOOT,EARLY] Specify the location of the initial ramdisk
2334 override in debugfs after boot.
2343 0 -- basic integrity auditing messages. (Default)
2344 1 -- additional integrity auditing messages.
2372 could harm performance of some high-throughput
2381 1 to 9 specify maximum depth of C-state.
2390 algorithms for p-state selection. There are two
2391 P-state selection algorithms provided by
2394 on whether or not the hardware managed P-states
2401 used along with the hardware-managed P-states (HWP)
2405 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2406 instead of acpi-cpufreq may disable platform features, such
2408 P-States information being indicated to OSPM and therefore
2411 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2424 Allow per-logical-CPU P-State performance control limits using
2427 Do not enable capacity-aware scheduling (CAS) on
2430 intremap= [X86-64,Intel-IOMMU,EARLY]
2435 BIOS x2APIC opt-out request will be ignored
2478 AMD Gart HW IOMMU-specific options:
2497 Do scatter-gather (SG) merging. Implies "force"
2501 Don't do scatter-gather (SG) merging.
2514 0 - Try to allocate a 32-bit DMA address first, before
2516 1 - Allocate directly from the full usable range,
2518 greater than 32-bit addressing.
2522 0 - Lazy mode.
2528 1 - Strict mode.
2531 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2533 legacy driver-specific options takes precedence.
2538 0 - Use IOMMU translation for DMA.
2539 1 - Bypass the IOMMU for DMA.
2540 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2542 io7= [HW] IO7 for Marvel-based Alpha systems
2557 See Documentation/admin-guide/nfs/nfsroot.rst.
2593 Enables support for pseudo-NMIs in the kernel. This
2598 [RISC-V,EARLY]
2600 as IPIs. Intended for system where IMSIC is trap-n-emulated,
2619 [Deprecated - use cpusets instead]
2620 Format: [flag-list,]<cpu-list>
2653 "number of CPUs in system - 1".
2679 The format of <cpu-list> is described above.
2683 ivrs_ioapic [HW,X86-64]
2684 Provide an override to the IOAPIC-ID<->DEVICE-ID
2688 For example, to map IOAPIC-ID decimal 10 to
2694 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2697 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2701 ivrs_hpet [HW,X86-64]
2702 Provide an override to the HPET-ID<->DEVICE-ID
2706 For example, to map HPET-ID decimal 10 to
2712 * To map HPET-ID decimal 0 to PCI device 00:14.0
2715 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2719 ivrs_acpihid [HW,X86-64]
2720 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2724 For example, to map UART-HID:UID AMD0020:0 to
2730 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2733 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2747 Do not unregister boot console at start. This is only
2749 between unregistering the boot console and initializing
2757 the kernel for non-movable allocations. The requested
2767 subsystem. Note that allocations like PTEs-from-HighMem
2775 for non-movable allocations and remaining memory is used
2786 gdb or control-c on the dbgp connection. When
2787 not using this parameter you use sysrq-g to break into
2792 or a supported polling keyboard driver (non-usb).
2801 If the boot console provides the ability to read
2812 blank and the first boot console that implements
2821 "0" | "off" | "n" - kexec handover is disabled
2822 "1" | "on" | "y" - kexec handover is enabled
2828 ranges that can only be used for non-kernel
2839 parameter defines the size of additional per-node
2841 (in percents) of memory that was used during boot.
2844 Configure the RouterBoard 532 series on-chip
2847 kmemleak= [KNL,EARLY] Boot-time kmemleak enable/disable
2853 kprobe_event=[probe-list]
2854 [FTRACE] Add kprobe events and enable at boot time.
2855 The probe-list is a semicolon delimited list of probe
2864 Boot Parameter" section.
2885 execution by eliminating the write-protection faults
2912 virtualization on-demand when creating and destroying
2920 is that doing so may interfere with using out-of-tree
2931 auto : Deploy workaround based on the presence of
2934 Default is 'auto'.
2947 back to huge pages. If the value is a non-zero N, KVM will
2952 kvm-amd.nested= [KVM,AMD] Control nested virtualization feature in
2955 kvm-amd.npt= [KVM,AMD] Control KVM's use of Nested Page Tables,
2956 a.k.a. Two-Dimensional Page Tables. Default is 1
2960 kvm-arm.mode=
2966 nvhe: Standard nVHE-based mode, without support for
2973 nested: VHE-based mode with support for nested
2981 command-line.
2985 kvm-arm.vgic_v3_group0_trap=
2986 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-0
2989 kvm-arm.vgic_v3_group1_trap=
2990 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-1
2993 kvm-arm.vgic_v3_common_trap=
2997 kvm-arm.vgic_v4_enable=
3001 kvm-arm.wfe_trap_policy=
3010 kvm-arm.wfi_trap_policy=
3027 kvm-intel.ept= [KVM,Intel] Control KVM's use of Extended Page Tables,
3028 a.k.a. Two-Dimensional Page Tables. Default is 1
3032 kvm-intel.emulate_invalid_guest_state=
3034 state. Ignored if kvm-intel.enable_unrestricted_guest=1,
3040 kvm-intel.flexpriority=
3045 kvm-intel.nested=
3049 kvm-intel.unrestricted_guest=
3055 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
3056 CVE-2018-3620.
3067 kvm-intel.vpid= [KVM,Intel] Control KVM's use of Virtual Processor
3087 on - enable the interface for the mitigation
3103 boot. Hypervisors will issue a warning
3121 boot. Hypervisors will issue a warning
3133 boot. Hypervisors will issue a warning
3152 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
3158 lapic [X86-32,APIC,EARLY] Enable the local APIC even if BIOS
3162 value for LAPIC timer one-shot implementation. Default
3185 libata.force= [LIBATA] Force configurations. The format is a comma-
3197 first fan-out link behind PMP device. It does not
3211 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
3218 * rstonce: only attempt one reset during hot-unplug
3261 * external: Mark port as external (hotplug-capable).
3315 Specify the number of self-propagating call_rcu()
3323 occasional long-duration lock hold time. Defaults
3334 Set the number of locking read-acquisition kthreads.
3339 Set the number of locking write-acquisition kthreads.
3342 Set time (s) after boot for CPU-hotplug testing.
3345 Set time (s) between CPU-hotplug operations, or
3346 zero to disable CPU-hotplug testing.
3349 Do periodic testing of real-time lock priority
3354 non-real-time spinlocks, due to their disabling
3355 of preemption. Note that non-realtime mutexes
3368 Set task-shuffle interval (jiffies). Shuffling
3369 tasks allows some CPUs to go into dyntick-idle
3373 Set time (s) after boot system shutdown. This
3374 is useful for hands-off automated testing.
3393 Run the write-side locktorture kthreads at
3394 sched_set_fifo() real-time priority.
3412 7 (KERN_DEBUG) debug-level messages
3424 logo.nologo [FB] Disables display of the built-in Linux logo.
3427 kernel boot problems.
3432 lp=auto printer driver. 'lp=reset' (which can be
3439 'parport0'. Specifying 'lp=auto' instead of a
3442 an IEEE 1284-compliant printer is attached; if
3448 time-consuming boot-time autodetection (up to 250 ms per
3450 the correct value for your kernel, boot with normal
3468 Example: machtype=lemote-yeeloong-2f-7inch
3480 (loop.max_loop) unconditionally pre-created at init time. The default
3483 devices can be requested on-demand with the
3484 /dev/loop-control interface.
3486 mce= [X86-{32,64}]
3523 do not opt-in to Local MCE delivery. Use legacy method
3537 disable boot machine check logging.
3544 don't overwrite the bios-set CMCI threshold. This boot
3553 force-enable recoverable machine check code paths
3559 See Documentation/admin-guide/md.rst.
3566 Control mitigation for the Micro-architectural Data
3581 full - Enable MDS mitigation on vulnerable CPUs
3582 full,nosmt - Enable MDS mitigation and disable
3584 off - Unconditionally disable MDS mitigation
3586 On TAA-affected machines, mds=off can be prevented by
3595 For details see: Documentation/admin-guide/hw-vuln/mds.rst
3600 mem=nn[KMG] [KNL,BOOT,EARLY] Force usage of a specific amount
3610 [ARC,MICROBLAZE] - the limit applies only to low memory,
3613 [ARM64] - only limits memory covered by the linear
3621 Note that this only takes effects during boot time since
3622 in above case 3, memory may need be hot added after boot
3626 [ARM,MIPS,EARLY] - override the memory layout
3633 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
3640 per-device physically contiguous DMA buffers.
3648 See Documentation/admin-guide/mm/memory-hotplug.rst.
3673 Example: Exclude memory from 0x18690000-0x1869ffff
3687 memmap=<size>%<offset>-<oldtype>+<newtype>
3689 from <oldtype> to <newtype>. If "-<oldtype>" is left
3704 repeatable BIOS-originated corruption always
3748 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
3754 Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
3758 s2idle - Suspend-To-Idle
3759 shallow - Power-On Suspend or equivalent (if supported)
3760 deep - Suspend-To-RAM or equivalent (if supported)
3761 See Documentation/admin-guide/pm/sleep-states.rst.
3763 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
3779 0 - The attached screen is the 3.5" TFT
3780 1 - The attached screen is the 7" TFT
3781 2 - The VGA Shield is attached (1024x768)
3785 b - Enable backlight. The TFT backlight pin will be
3789 c - Enable the s3c camera interface.
3790 t - Reserved for enabling touchscreen support. The
3794 https://repo.or.cz/w/linux-2.6/mini2440.git
3799 arch-independent options, each of which is an
3800 aggregation of existing arch-specific options.
3830 ssbd=force-off [ARM64]
3838 auto (default)
3843 have other ways of avoiding SMT-based attacks.
3846 auto,nosmt
3854 retbleed=auto,nosmt [X86]
3857 supports attack-vector based controls as documented in
3858 Documentation/admin-guide/hw-vuln/attack_vector_controls.rst
3882 full - Enable mitigation on vulnerable CPUs
3884 full,nosmt - Enable mitigation and disable SMT on
3887 off - Unconditionally disable mitigation
3900 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3930 module_blacklist= [KNL] Do not load a comma-separated list of
3955 movable_node [KNL,EARLY] Boot-time switch to make hotplugable memory
3962 Format: <name>,<region-number>,<size>,<offset>
3965 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3976 registers at boot time.
4004 something different and driver-specific.
4044 [NFS] enable 64-bit inode numbers.
4045 If zero, the NFS client will fake up a 32-bit inode
4047 of returning the full 64-bit number.
4048 The default is to return 64-bit inode numbers.
4083 [NFS4] Specify an additional fixed unique ident-
4114 driver. A non-zero value sets the minimum interval
4119 server-to-server copies for which this server is
4131 server-to-server copy, knfsd temporarily mounts
4138 See Documentation/admin-guide/nfs/nfsroot.rst.
4140 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
4141 See Documentation/admin-guide/nfs/nfsroot.rst.
4144 See Documentation/admin-guide/nfs/nfsroot.rst.
4148 NMI stack-backtrace request.
4157 0 - turn hardlockup detector in nmi_watchdog off
4158 1 - turn hardlockup detector in nmi_watchdog on
4159 rNNN - configure the watchdog with raw perf event 0xNNN
4172 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
4176 no4lvl [RISCV,EARLY] Disable 4-level and 5-level paging modes.
4177 Forces kernel to use 3-level paging instead.
4179 no5lvl [X86-64,RISCV,EARLY] Disable 5-level paging mode. Forces
4180 kernel to use 4-level paging instead.
4211 nodsp [SH] Disable hardware DSP at boot time.
4215 no_entry_flush [PPC,EARLY] Don't flush the L1-D cache when entering the kernel.
4217 noexec32 [X86-64]
4218 This affects only 32-bit executables.
4219 noexec32=on: enable non-executable mappings (default)
4221 noexec32=off: disable non-executable mappings
4228 nofpu [MIPS,SH] Disable hardware FPU at boot time.
4232 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4234 legacy floating-point registers on task switch.
4263 nohz_full= [KNL,BOOT,SMP,ISOL]
4267 whenever possible. The boot CPU will be forced outside
4271 rcu_nocbs= boot parameter.
4279 nointremap [X86-64,Intel-IOMMU,EARLY] Do not enable interrupt
4281 [Deprecated - use intremap=off]
4287 noirqdebug [X86-32] Disables the code which attempts to detect and
4297 no-kvmapf [X86,KVM,EARLY] Disable paravirtualized asynchronous page
4300 no-kvmclock [X86,KVM,EARLY] Disable paravirtualized KVM clock driver
4302 nolapic [X86-32,APIC,EARLY] Do not enable or use the local APIC.
4304 nolapic_timer [X86-32,APIC,EARLY] Do not use the local APIC timer.
4306 nomce [X86-32] Disable Machine Check Exception
4308 nomfgpt [X86-32] Disable Multi-Function General Purpose
4314 not load if they could possibly displace the pre-
4317 perform display-mode changes or accelerated rendering.
4330 nopcid [X86-64,EARLY] Disable the PCID cpu feature.
4335 nopti [X86-64,EARLY]
4351 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
4357 no-scroll [VGA] Disables scrollback.
4358 This is required for the Braillex ib80-piezo Braille
4361 nosgx [X86-64,SGX,EARLY] Disables Intel SGX kernel support.
4381 nosoftlockup [KNL] Disable the soft-lockup detector.
4387 nospectre_bhb [ARM64,EARLY] Disable all mitigations for Spectre-BHB (branch
4400 no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,LOONGARCH,EARLY]
4407 timer IRQ sources, i.e., the IO-APIC timer. This can
4412 [PPC,EARLY] Don't flush the L1-D cache after accessing user data.
4425 no-vmw-sched-clock
4430 soft-lockup and NMI watchdog (hard-lockup).
4434 nox2apic [X86-64,APIC,EARLY] Do not enable x2APIC mode.
4442 enabling legacy floating-point and sse state.
4464 n. So during boot up some boot time memory for per-cpu
4465 variables need be pre-allocated for later physical cpu
4492 soft-reserved memory partitioning.
4498 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
4500 This can be set from sysctl after boot.
4501 See Documentation/admin-guide/sysctl/vm.rst for details.
4504 See Documentation/core-api/debugging-via-ohci1394.rst for more
4519 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
4523 boundary - index of last SLC block on Flex-OneNAND.
4525 lock - Configure if Flex-OneNAND boundary should be locked.
4544 page_owner= [KNL,EARLY] Boot-time page_owner enabling option.
4550 page_poison= [KNL,EARLY] Boot-time parameter changing the state of
4578 See Documentation/admin-guide/tainted-kernels.rst for
4627 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
4628 Use 'auto' to force the driver to use any
4633 should be numbers, or 'auto' (for using detected
4650 Set to non-zero to probe primary and secondary ISA
4656 Set to non-zero if a chip is present that snoops speed
4704 Set to non-zero to probe tertiary and further ISA
4720 Set to non-zero to probe QDI controllers. By default
4725 Set to non-zero to probe Winbond controllers. Use
4772 bios [X86-32] force use of PCI BIOS, don't access
4774 has a non-standard PCI host bridge.
4775 nobios [X86-32] disallow use of PCI BIOS, only direct
4781 data in IO port 0xCFC, both 32-bit).
4783 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
4784 the function, IO port 0xCFA, also 8-bit, sets
4786 through ports 0xC000-0xCFFF).
4790 enabled, this kernel boot option can be used to
4793 root domains (aka PCI segments, in ACPI-speak).
4800 enabled, this kernel boot option can be used to
4801 disable the use of MSI interrupts system-wide.
4802 noioapicquirk [APIC] Disable all boot interrupt quirks.
4803 Safety option to keep boot IRQs enabled. This
4805 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
4806 primary IO-APIC for bridges that cannot disable
4807 boot IRQs. This fixes a source of spurious IRQs
4810 boot IRQ equivalent of an IRQ that connects to
4811 a chipset where boot IRQs cannot be disabled.
4813 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
4837 F0000h-100000h range.
4842 assign-busses [X86] Always assign all PCI bus
4863 <linux-pci@vger.kernel.org>.
4867 a bug to <linux-pci@vger.kernel.org>.
4879 bfsort Sort PCI devices into breadth-first order.
4882 nobfsort Don't sort PCI devices into breadth-first order.
4884 tuning and use the BIOS-configured MPS defaults.
4894 configuration allows peer-to-peer DMA between
4897 that hot-added devices will work.
4912 A PCI-PCI bridge can be specified if resource
4918 for 4096-byte alignment.
4920 end-to-end CRC checking). Only effective if
4951 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4982 bit-0 : ACS Source Validation
4983 bit-1 : ACS Translation Blocking
4984 bit-2 : ACS P2P Request Redirect
4985 bit-3 : ACS P2P Completion Redirect
4986 bit-4 : ACS Upstream Forwarding
4987 bit-5 : ACS P2P Egress Control
4988 bit-6 : ACS Direct Translated P2P
4998 Validation unchanged from whatever power-up
5008 is enabled, this kernel boot option can be used
5010 system-wide.
5024 dpc-native Use native PCIe service for DPC only. May
5041 Keep all power-domains already enabled by bootloader on,
5047 boot time.
5059 pirq= [SMP,APIC] Manual mp-table setup
5060 See Documentation/arch/x86/i386/IO-APIC.rst.
5064 See also Documentation/admin-guide/parport.rst.
5081 /sys/power/pm_async sysfs knob at boot time.
5083 resume of devices during system-wide power transitions.
5085 dependencies are not well-defined, or for debugging
5091 Enable suspend/resume debug messages during boot up.
5095 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
5104 { on | off | curr | res | no-curr | no-res }
5149 none - Limited to cond_resched() calls
5150 voluntary - Limited to cond_resched() and might_sleep() calls
5151 full - Any section that isn't explicitly preempt disabled
5155 lazy - Scheduler controlled. Similar to full but instead
5161 print-fatal-signals=
5167 coredump - etc.
5170 you might want to try "ulimit -i unlimited".
5182 or lockdep-detected issues (only if lock debug is on).
5190 Allows storing messages from non-panic CPUs into
5192 flushed to consoles by the panic-CPU on
5193 a best-effort basis.
5199 on - unlimited logging to /dev/kmsg from userspace
5200 off - logging to /dev/kmsg disabled
5201 ratelimit - ratelimit the logging
5212 - 'always': traditional behavior always allows mem overrides.
5213 - 'ptrace': only allow mem overrides for active ptracers.
5214 - 'never': never allow mem overrides.
5218 Limit processor to maximum C-state
5222 Ignore the _CST method to determine C-states,
5229 Param: "schedule" - profile schedule points.
5230 Param: "kvm" - profile VM exits.
5231 Param: <number> - step/bucket size as a power of 2 for
5262 pti= [X86-64] Control Page Table Isolation of user and
5267 on - unconditionally enable
5268 off - unconditionally disable
5269 auto - kernel detects whether your CPU model is
5272 Not specifying this option is equivalent to pti=auto.
5275 [KNL] Number of legacy pty's. Overwrites compiled-in
5287 See Documentation/admin-guide/md.rst.
5290 See Documentation/admin-guide/blockdev/ramdisk.rst.
5309 cross-syscall address exposures. This is only
5315 ras=option[,option,...] [KNL] RAS-specific options
5321 rcu_nocbs[=cpu-list]
5326 enable the no-callback CPU mode, which prevents
5331 "p" for RCU-preempt, "s" for RCU-sched, and "g"
5335 and real-time workloads. It can also improve
5339 list of CPUs is set to no-callback mode from boot.
5343 no-callback mode from boot but the mode may be
5354 This improves the real-time response for the
5365 Do only a one-line RCU CPU stall warning when
5366 there is an ongoing too-long CSD-lock wait.
5372 If triggered before the RCU grace-period machinery
5377 out at early boot. This is used for diagnostic
5382 RCU grace-period cleanup.
5386 RCU grace-period initialization.
5390 RCU grace-period pre-initialization, that is,
5391 the propagation of recent CPU-hotplug changes up
5395 Set delay from grace-period initialization to
5408 soliciting quiescent-state help from
5419 rcutree.kthread_prio= [KNL,BOOT]
5420 Set the SCHED_FIFO priority of the RCU per-CPU
5423 and for the RCU grace-period kthreads (rcu_bh,
5425 set, valid values are 1-99 and the default is 1
5426 (the least-favored priority). Otherwise, when
5427 RCU_BOOST is not set, valid values are 0-99 and
5428 the default is zero (non-realtime operation).
5433 On callback-offloaded (rcu_nocbs) CPUs,
5436 use of the ->nocb_bypass list. However, in the
5437 common non-flooded case, RCU queues directly to
5438 the main ->cblist in order to avoid the extra
5439 overhead of the ->nocb_bypass list and its lock.
5441 a single jiffy, RCU pre-queues the callbacks into
5442 the ->nocb_bypass queue. The definition of "too
5443 many" is supplied by this kernel boot parameter.
5446 On callback-offloaded (rcu_nocbs) CPUs, avoid
5459 batch limiting is re-enabled.
5463 RCU's force-quiescent-state scan will aggressively
5467 on rcutree.qhimark at boot time and to zero to
5471 Set the page-cache refill delay (in milliseconds)
5472 in response to low-memory conditions. The range
5476 Set the shift-right count to use to compute
5477 the callback-invocation batch limit bl from
5484 Please note that this callback-invocation batch
5485 limit applies only to non-offloaded callback
5494 cache-to-cache transfer latencies.
5500 and for NUMA systems with large remote-access
5516 the wakeup overhead on the global grace-period
5518 each group's NOCB grace-period kthread.
5521 Cause the grace-period kthread to get an extra
5523 it should at force-quiescent-state time.
5536 this specifies an rcu_read_unlock()-time delay
5540 of RCU-protected pointers after the relevant
5550 per-CPU rcuc kthreads. Defaults to a non-zero
5555 this kernel boot parameter, forcibly setting it
5573 or pass a boot parameter "rcutree.rcu_normal_wake_from_gp=1"
5576 disabled by the boot parameter passing 0.
5580 grace-period primitives such as call_rcu().
5591 grace-period primitives.
5594 Set test-start holdoff period. The purpose of
5596 test until boot completes in order to avoid
5612 Test the double-argument variant of kfree_rcu().
5614 rcuscale.kfree_rcu_test_single, both the single-
5615 and double-argument variants are tested.
5618 Test the single-argument variant of kfree_rcu().
5620 rcuscale.kfree_rcu_test_double, both the single-
5621 and double-argument variants are tested.
5635 does not affect the data-collection interval,
5640 Set number of RCU readers. The value -1 selects
5642 "n" less than -1 selects N-n+1, where N is again
5643 the number of CPUs. For example, -2 selects N
5644 (the number of CPUs), -3 selects N+1, and so on.
5645 A value of "n" less than or equal to -N selects
5658 complete. This is useful for hands-off automated
5665 Write-side holdoff between grace periods,
5670 Additional write-side holdoff between grace
5688 for RCU grace-period forward-progress testing
5695 Specify the fraction of a CPU-stall-warning
5696 period to do tight-loop forward-progress testing.
5700 forward-progress tests.
5704 need_resched() during tight-loop forward-progress
5708 Use conditional/asynchronous update-side
5709 normal-grace-period primitives, if available.
5712 Use conditional/asynchronous update-side
5713 expedited-grace-period primitives, if available.
5716 Use conditional/asynchronous update-side
5717 normal-grace-period primitives that also take
5722 Use conditional/asynchronous update-side
5723 expedited-grace-period primitives that also take
5747 Use expedited update-side primitives, if available.
5750 Use normal (non-expedited) asynchronous
5751 update-side primitives, if available.
5754 Use polled update-side normal-grace-period
5758 Use polled update-side expedited-grace-period
5762 Use polled update-side normal-grace-period
5767 Use polled update-side expedited-grace-period
5791 Use normal (non-expedited) synchronous
5792 update-side primitives, if available. If all
5796 they are all non-zero.
5799 Enable grace-period wrap lag testing. Setting
5804 Set the value for grace-period wrap lag during
5819 the grace-period wrap lag will be set to the
5829 Leak an RCU-protected pointer out of the reader.
5844 Set number of RCU callback-offload togglers.
5849 callback-offload toggling attempts.
5852 Set number of RCU readers. The value -1 selects
5853 N-1, where N is the number of CPUs. A value
5854 "n" less than -1 selects N-n-2, where N is again
5855 the number of CPUs. For example, -2 selects N
5856 (the number of CPUs), -3 selects N+1, and so on.
5859 Enable debug-object double-call_rcu() testing.
5862 Set time (s) after boot for CPU-hotplug testing.
5865 Set time (jiffies) between CPU-hotplug operations,
5866 or zero to disable CPU-hotplug testing.
5870 by a high-priority FIFO real-time task. Set to
5879 second) between preemptions by a high-priority
5880 FIFO real-time task. This delay is mediated
5885 The number of times in a given read-then-exit
5886 episode that a set of read-then-exit kthreads
5891 read-then-exit testing episodes.
5896 are entered from low-order bit up, and are
5898 0x1 bit is normal readers, 0x2 NMI-safe readers,
5899 and 0x4 light-weight readers.
5902 Set task-shuffle interval (s). Shuffling tasks
5903 allows some CPUs to go into dyntick-idle mode
5907 Set time (s) after boot system shutdown. This
5908 is useful for hands-off automated testing.
5917 any other stall-related activity. Note that
5923 in scheduling-while-atomic splats.
5929 Time to wait (s) after boot before inducing stall.
5942 grace-period kthread to test RCU CPU stall
5966 of RCU priority-boost testing. Defaults to zero,
5973 Test RCU's dyntick-idle handling. See also the
5998 during early boot, that is, during the time
6028 Use expedited grace-period primitives, for
6032 real-time latency, and degrade energy efficiency.
6036 Use only normal grace-period primitives,
6039 real-time latency, CPU utilization, and
6041 increased grace-period latency. This parameter
6046 Once boot has completed (that is, after
6048 only normal grace-period primitives. No effect
6052 this kernel boot parameter, forcibly setting
6054 post-boot attempt at an expedited RCU grace
6055 period to instead use normal non-expedited
6056 grace-period processing.
6064 set to the default value of -1.
6067 Set the minimum number of callback-queuing-time
6068 lock-contention events per jiffy required to
6069 cause the RCU Tasks flavors to switch to per-CPU
6072 the default value of -1.
6077 of -1 allows this to be automatically (and
6085 number avoids disturbing real-time workloads,
6090 cancel laziness on that CPU. Use -1 to disable
6100 only printed prior to the stall-warning message
6140 Run the RCU early boot self tests
6148 force - Override the decision by the kernel to hide the
6187 There are some built-in platform specific "quirks"
6188 - you may see: "reboot: <name> series board detected.
6192 built-in quirk table, and use the generic default
6221 there may be boot problems on some systems.
6225 Set test-start holdoff period. The purpose of
6227 test until boot completes in order to avoid
6240 but the default has already reduced the per-pass
6245 Set number of readers. The default value of -1
6254 Set the read-side critical-section duration,
6258 Specify the read-protection implementation to test.
6284 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
6302 was from a previous boot, the new reservation will be at a
6306 boot, as there may be cases where the memory will not be
6314 reservetop= [X86-32,EARLY]
6331 See Documentation/power/swsusp-and-swap-files.rst
6340 retain_initrd [RAM] Keep initrd memory after extraction. After boot, it will
6347 AMD-based UNRET and IBPB mitigations alone do not stop
6349 sibling threads. For that reason, STIBP is used on pro-
6353 off - no mitigation
6354 auto - automatically select a migitation
6355 auto,nosmt - automatically select a mitigation,
6359 ibpb - On AMD, mitigate short speculation
6364 ibpb,nosmt - Like "ibpb" above but will disable SMT
6368 unret - Force enable untrained return thunks,
6369 only effective on AMD f15h-f17h based
6371 unret,nosmt - Like unret, but will disable SMT when STIBP
6375 Selecting 'auto' will choose a mitigation method at run
6378 Not specifying this option is equivalent to retbleed=auto.
6403 ro [KNL] Mount root device read-only on boot
6406 on Mark read-only kernel memory as read-only (default).
6407 off Leave read-only kernel memory writable for debugging.
6408 full Mark read-only kernel memory and aliases as read-only
6415 debug-uart get routed to the D+ and D- pins of the usb
6421 block/early-lookup.c for details.
6451 rw [KNL] Mount root device read-write on boot
6480 solution to mutex-based priority inversion.
6510 to 10 seconds for built-in smp_call_function()
6517 that requesting even small non-zero numbers of
6524 The default of -1 specifies a number of kthreads
6529 test before initiating CPU-hotplug operations.
6533 CPU-hotplug operations. Specifying zero (which
6534 is the default) disables CPU-hotplug operations.
6540 Non-zero values are useful for automated tests.
6563 "wait" parameter. A value of -1 selects the
6564 default if all other weights are -1. However,
6566 value of -1 will instead select a weight of zero.
6571 non-zero "wait" parameter. See weight_single.
6584 non-zero "wait" parameter. See weight_single
6596 non-zero "wait" parameter. See weight_single
6607 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
6608 1 -- enable.
6613 enable at boot. This has been deprecated by the
6616 selinux= [SELINUX] Disable or enable SELinux at boot time.
6619 0 -- disable.
6620 1 -- enable.
6623 serialnumber [BUGS=X86-32]
6625 sev=option[,option...] [X86-64]
6631 Do not enable SEV-SNP (applies to host/hypervisor
6634 SEV-SNP guests.
6642 to set it to "all" by meaning -- no limit here.
6654 Documentation/admin-guide/mm/slab.rst.
6665 Documentation/admin-guide/mm/slab.rst.
6681 Documentation/admin-guide/mm/slab.rst.
6687 Documentation/admin-guide/mm/slab.rst.
6702 Documentation/admin-guide/mm/slab.rst.
6729 using the csdlock_debug- kernel parameter.
6734 system. By default, let CSD-lock acquisition
6736 for this value provides a 5-minute timeout.
6738 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
6739 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
6740 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
6741 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
6742 smsc-ircc2.ircc_irq= [HW] IRQ line
6743 smsc-ircc2.ircc_dma= [HW] DMA channel
6744 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
6754 Default: -1 (no limit)
6757 [KNL] Should the soft-lockup detector generate panics.
6760 A value of 1 instructs the soft-lockup detector
6761 to panic the machine when a soft-lockup occurs. It is
6764 respective build-time switch to that functionality.
6767 [KNL] Should the soft-lockup detector generate
6772 See Documentation/admin-guide/laptops/sonypi.rst
6779 on - (default) Enable the HW or SW mitigation as
6782 vmexit - On systems which don't have the HW mitigation
6785 protected from VM-originated BHI attacks, but
6787 off - Disable the mitigation.
6794 on - unconditionally enable, implies
6796 off - unconditionally disable, implies
6798 auto - kernel detects whether your CPU model is
6801 Selecting 'on' will, and 'auto' may, choose a
6817 retpoline - replace indirect branches
6818 retpoline,generic - Retpolines
6819 retpoline,lfence - LFENCE; indirect branch
6820 retpoline,amd - alias for retpoline,lfence
6821 eibrs - Enhanced/Auto IBRS
6822 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
6823 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
6824 ibrs - use IBRS to protect kernel
6827 spectre_v2=auto.
6834 on - Unconditionally enable mitigations. Is
6837 off - Unconditionally disable mitigations. Is
6840 prctl - Indirect branch speculation is enabled,
6846 - Like "prctl" above, but only STIBP is
6852 - Same as "prctl" above, but all seccomp
6857 - Like "seccomp" above, but only STIBP is
6862 auto - Kernel selects the mitigation depending on
6868 spectre_v2_user=auto.
6873 off - Disable mitigation
6874 microcode - Enable microcode mitigation only
6875 safe-ret - Enable sw-only safe RET mitigation (default)
6876 ibpb - Enable mitigation by issuing IBPB on
6878 ibpb-vmexit - Issue IBPB only on VMEXIT
6879 (cloud-specific mitigation)
6904 on - Unconditionally disable Speculative Store Bypass
6905 off - Unconditionally enable Speculative Store Bypass
6906 auto - Kernel detects whether the CPU model contains an
6912 prctl - Control Speculative Store Bypass per thread
6916 seccomp - Same as "prctl" above, but all seccomp threads
6924 on,auto - On Power8 and Power9 insert a store-forwarding
6928 off - No action.
6931 spec_store_bypass_disable=auto.
6942 off - not enabled
6944 warn - the kernel will emit rate-limited warnings
6952 fatal - the kernel will send SIGBUS to applications
6957 ratelimit:N -
6977 Certain CPUs are vulnerable to an MDS-like
6997 This kernel-boot parameter defaults to 128,
6998 but takes effect only when the low-order four
7000 (decide at boot).
7010 3: Decide at boot time (default).
7015 instead of the compile-time CONFIG_NR_CPUS.
7019 grace-period sequence counter wrap for the
7020 srcu_data structure's ->srcu_gp_seq_needed field.
7035 Specifies the number of no-delay instances
7042 Specifies the per-grace-period phase, number of
7043 non-sleeping polls of readers. Beyond this limit,
7049 Specifies number of microseconds of non-sleeping
7050 delay between each non-sleeping poll of readers.
7053 Specifies the number of update-side contention
7058 set for contention-based conversions to occur.
7068 force-on: Unconditionally enable mitigation for
7070 force-off: Unconditionally disable mitigation for
7092 stack traces. Pools are allocated on-demand up to this
7096 Enabled the stack tracer on boot up.
7098 stacktrace_filter=[function-list]
7100 will trace at boot up. function-list is a comma-separated
7108 Set the STI (builtin display/keyboard on the HP-PARISC
7110 as the initial boot-console.
7165 auto the server chooses an appropriate mode
7170 to global on non-NUMA machines)
7195 <int> -- Number of I/O TLB slabs
7196 <int> -- Second integer after comma. Number of swiotlb
7199 force -- force using of bounce buffers even if they
7201 noforce -- Never use bounce buffers (for debugging)
7216 Ignore sysrq setting - this boot parameter will
7224 cache size. See Documentation/networking/ip-sysctl.rst
7231 Specify "mem" (for Suspend-to-RAM) or "standby" (for
7236 wakeup-capable RTC alarm.
7242 -1: disable all active trip points in all thermal zones
7246 -1: disable all critical trip points in all thermal zones
7253 -1: disable all passive trip points
7259 <deci-seconds>: poll all this frequency
7263 Format: <size>[KMG],<size>[KMG]:<state>;<size>[KMG]-<size>[KMG]:<state>
7268 See Documentation/admin-guide/mm/transhuge.rst for more
7276 Format: <size>[KMG],<size>[KMG]:<policy>;<size>[KMG]-<size>[KMG]:<policy>
7282 See Documentation/admin-guide/mm/transhuge.rst for more
7294 Prevent the CPU-hotplug component of torturing
7298 Dump the ftrace buffer at torture-test shutdown,
7302 with rotating-rust storage.
7307 disables verbose-printk() sleeping.
7310 Duration of each verbose-printk() sleep in jiffies.
7343 https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
7347 tracing ring buffer. This is useful for early boot up
7370 printing of events during boot up, as user space may
7380 at boot up.
7381 local - Use the per CPU time stamp counter
7385 global - Event time stamps are synchronize across
7388 counter - Simple counting of events (1, 2, ..)
7392 uptime - Use jiffies as the time stamp.
7393 perf - Use the same clock that perf uses.
7394 mono - Use ktime_get_mono_fast_ns() for time stamps.
7395 mono_raw - Use ktime_get_raw_fast_ns() for time
7397 boot - Use ktime_get_boot_fast_ns() for time stamps.
7401 trace_event=[event-list]
7403 to facilitate early boot debugging. The event-list is a
7404 comma-separated list of trace events to enable. See
7415 trace_instance=[instance-info]
7416 [FTRACE] Create a ring buffer instance early in boot up.
7440 traceoff - Have the tracing instance tracing disabled after it is created.
7441 traceprintk - Have trace_printk() write into this trace instance
7461 This will reserve 12 megabytes at boot up with a 4096 byte alignment
7471 it is recommend to disable tracing so that events from a previous boot do not
7472 mix with events of the current boot (unless you are debugging a random crash
7473 at boot up).
7479 can force a memory reset on boot which will clear any trace that was stored.
7488 trace_options=[option-list]
7489 [FTRACE] Enable or disable tracer options at boot.
7490 The option-list is a comma delimited list of options
7504 trace_trigger=[trigger-list]
7525 during the boot process. Since the trace buffer has a
7527 disable tracing after the boot is finished, otherwise
7530 the end of the boot process.
7550 See Documentation/admin-guide/mm/transhuge.rst
7557 See Documentation/admin-guide/mm/transhuge.rst
7564 See Documentation/admin-guide/mm/transhuge.rst
7572 - "tpm"
7573 - "tee"
7574 - "caam"
7575 - "dcp"
7585 - "kernel"
7586 - the same value as trusted.source: "tpm" or "tee"
7587 - "default"
7610 off - disable the mitigation
7611 on - enable the mitigation (default)
7612 user - mitigate only user/kernel transitions
7613 vm - mitigate only guest/host transitions
7621 high-resolution timer mode on older hardware, and in
7657 on - Enable TSX on the system. Although there are
7660 several previous speculation-related CVEs, and
7664 off - Disable TSX on the system. (Note that this
7672 auto - Disable TSX if X86_BUG_TAA is present,
7677 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7683 Similar to Micro-architectural Data Sampling (MDS)
7698 full - Enable TAA mitigation on vulnerable CPUs
7701 full,nosmt - Enable TAA mitigation and disable SMT on
7704 vulnerable to cross-thread TAA attacks.
7705 off - Unconditionally disable TAA mitigation
7707 On MDS-affected machines, tsx_async_abort=off can be
7719 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
7725 See also Documentation/input/devices/joystick-parport.rst
7727 udbg-immortal [PPC] When debugging early kernel crashes that
7729 console driver takes over, this boot options might
7733 Set number of hash buckets for UDP/UDP-Lite connections
7735 uhci-hcd.ignore_oc=
7737 Some badly-designed motherboards generate lots of
7762 unwind_debug [X86-64,EARLY]
7770 (default -1 = authorized (same as 1),
7776 for newly-detected USB devices (default 2). This
7804 [USB] Specifies timeout for the initial 64-byte
7811 [USB] A list of quirk entries to augment the built-in
7814 VendorID:ProductID:Flags. The IDs are 4-digit hex
7816 will change the built-in quirk; setting it if it is
7821 a 255-byte read);
7825 Set-Interface requests);
7844 (bInterval-1).
7882 usb-storage.delay_use=
7889 usb-storage.quirks=
7891 override the built-in unusual_devs list. List
7894 and Product ID values (4-digit hex numbers) and
7896 to a common usb-storage quirk flag as follows:
7938 medium is write-protected).
7947 1 - undefined instruction events
7948 2 - system calls
7949 4 - invalid data aborts
7950 8 - SIGSEGV faults
7951 16 - SIGBUS faults
7960 vdso32= [X86] Control the 32-bit vDSO
7961 vdso32=1: enable 32-bit VDSO
7962 vdso32=0 or vdso32=2: disable 32-bit VDSO
7972 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
8003 vga= [BOOT,X86-32] Select a particular video mode
8004 See Documentation/arch/x86/boot.rst and
8005 Documentation/admin-guide/svga.rst.
8007 This is actually a boot loader parameter; the value is
8011 May slow down system boot speed, especially when
8020 - Disable all of the above options
8022 vmalloc=nn[KMG] [KNL,BOOT,EARLY] Forces the vmalloc area to have an
8044 vsyscall= [X86-64,EARLY]
8047 code). Most statically-linked binaries and older
8071 see vga-softcursor.rst. Default: 2 = underline.
8076 This is a 16-member array composed of values
8077 ranging from 0-255.
8082 This is a 16-member array composed of values
8083 ranging from 0-255.
8088 This is a 16-member array composed of values
8089 ranging from 0-255.
8094 Set system-wide default UTF-8 mode for all tty's.
8095 Default is 1, i.e. UTF-8 mode is enabled for all
8100 Format=<-1|0|1>
8101 Set system-wide default for whether a cursor
8102 is shown on new VTs. Default is -1,
8107 vt.italic= [VT] Default color for italic text; 0-15.
8110 vt.underline= [VT] Default color for underlined text; 0-15.
8114 see Documentation/watchdog/watchdog-parameters.rst
8115 or other driver-specific files in the
8129 Format: <cpu-list>
8150 Per-cpu work items which run for longer than this
8153 them from noticeably delaying other per-cpu work
8171 Per-cpu workqueues are generally preferred because
8173 locality; unfortunately, per-cpu workqueues tend to
8176 Enabling this makes the per-cpu workqueues which
8190 Documentation/core-api/workqueue.rst.
8192 This can be changed after boot by writing to the
8203 forces round-robin CPU selection to flush out
8211 on - Enable writecombine, use WUC for ioremap_wc()
8212 off - Disable writecombine, use SUC for ioremap_wc()
8214 x2apic_phys [X86-64,APIC,EARLY] Use x2apic physical mode instead of
8218 xen_512gb_limit [KNL,X86-64,XEN]
8228 ide-disks -- unplug primary master IDE devices
8229 aux-ide-disks -- unplug non-primary-master IDE devices
8230 nics -- unplug network devices
8231 all -- unplug all emulated devices (NICs and IDE disks)
8232 unnecessary -- unplugging emulated devices is
8235 never -- do not unplug even if version check succeeds
8249 Select whether to always use non-faulting (safe) MSR
8269 xen_timer_slop= [X86-64,XEN,EARLY]
8277 The time (in seconds) to wait before giving up to boot
8294 preferred over the 2-level event handling, as it is
8311 xive.store-eoi=off [PPC]
8317 xhci-hcd.quirks [USB,KNL]
8326 early Call xmon as early as possible on boot; xmon