accept_memory= [MM] Format: { eager | lazy } default: lazy By default, unaccepted memory is accepted lazily to avoid prolonged boot times. The lazy option will add some runtime overhead until all memory is eventually accepted. In most cases the overhead is negligible. For some workloads or for debugging purposes accept_memory=eager can be used to accept all memory at once during boot. acpi= [HW,ACPI,X86,ARM64,RISCV64,EARLY] Advanced Configuration and Power Interface Format: { force | on | off | strict | noirq | rsdt | copy_dsdt | nospcr } force -- enable ACPI if default was off on -- enable ACPI but allow fallback to DT [arm64,riscv64] off -- disable ACPI if default was on noirq -- do not use ACPI for IRQ routing strict -- Be less tolerant of platforms that are not strictly ACPI specification compliant. rsdt -- prefer RSDT over (default) XSDT copy_dsdt -- copy DSDT to memory nospcr -- disable console in ACPI SPCR table as default _serial_ console on ARM64 For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or "acpi=nospcr" are available For RISCV64, ONLY "acpi=off", "acpi=on" or "acpi=force" are available See also Documentation/power/runtime_pm.rst, pci=noacpi acpi_apic_instance= [ACPI,IOAPIC,EARLY] Format: <int> 2: use 2nd APIC table, if available 1,0: use 1st APIC table default: 0 acpi_backlight= [HW,ACPI] { vendor | video | native | none } If set to vendor, prefer vendor-specific driver (e.g. thinkpad_acpi, sony_acpi, etc.) instead of the ACPI video.ko driver. If set to video, use the ACPI video.ko driver. If set to native, use the device's native backlight mode. If set to none, disable the ACPI backlight interface. acpi_force_32bit_fadt_addr [ACPI,EARLY] force FADT to use 32 bit addresses rather than the 64 bit X_* addresses. Some firmware have broken 64 bit addresses for force ACPI ignore these and use the older legacy 32 bit addresses. acpica_no_return_repair [HW, ACPI] Disable AML predefined validation mechanism This mechanism can repair the evaluation result to make the return objects more ACPI specification compliant. This option is useful for developers to identify the root cause of an AML interpreter issue when the issue has something to do with the repair mechanism. acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] acpi.debug_level= [HW,ACPI,ACPI_DEBUG] Format: <int> CONFIG_ACPI_DEBUG must be enabled to produce any ACPI debug output. Bits in debug_layer correspond to a _COMPONENT in an ACPI source file, e.g., #define _COMPONENT ACPI_EVENTS Bits in debug_level correspond to a level in ACPI_DEBUG_PRINT statements, e.g., ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... The debug_level mask defaults to "info". See Documentation/firmware-guide/acpi/debug.rst for more information about debug layers and levels. Enable processor driver info messages: acpi.debug_layer=0x20000000 Enable AML "Debug" output, i.e., stores to the Debug object while interpreting AML: acpi.debug_layer=0xffffffff acpi.debug_level=0x2 Enable all messages related to ACPI hardware: acpi.debug_layer=0x2 acpi.debug_level=0xffffffff Some values produce so much output that the system is unusable. The "log_buf_len" parameter may be useful if you need to capture more output. acpi_enforce_resources= [ACPI] { strict | lax | no } Check for resource conflicts between native drivers and ACPI OperationRegions (SystemIO and SystemMemory only). IO ports and memory declared in ACPI might be used by the ACPI subsystem in arbitrary AML code and can interfere with legacy drivers. strict (default): access to resources claimed by ACPI is denied; legacy drivers trying to access reserved resources will fail to bind to device using them. lax: access to resources claimed by ACPI is allowed; legacy drivers trying to access reserved resources will bind successfully but a warning message is logged. no: ACPI OperationRegions are not marked as reserved, no further checks are performed. acpi_force_table_verification [HW,ACPI,EARLY] Enable table checksum verification during early stage. By default, this is disabled due to x86 early mapping size limitation. acpi_irq_balance [HW,ACPI] ACPI will balance active IRQs default in APIC mode acpi_irq_nobalance [HW,ACPI] ACPI will not move active IRQs (default) default in PIC mode acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA Format: <irq>,<irq>... acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for use by PCI Format: <irq>,<irq>... acpi_mask_gpe= [HW,ACPI] Due to the existence of _Lxx/_Exx, some GPEs triggered by unsupported hardware/firmware features can result in GPE floodings that cannot be automatically disabled by the GPE dispatcher. This facility can be used to prevent such uncontrolled GPE floodings. Format: <byte> or <bitmap-list> acpi_no_auto_serialize [HW,ACPI] Disable auto-serialization of AML methods AML control methods that contain the opcodes to create named objects will be marked as "Serialized" by the auto-serialization feature. This feature is enabled by default. This option allows to turn off the feature. acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump kernels. acpi_no_static_ssdt [HW,ACPI,EARLY] Disable installation of static SSDTs at early boot time By default, SSDTs contained in the RSDT/XSDT will be installed automatically and they will appear under /sys/firmware/acpi/tables. This option turns off this feature. Note that specifying this option does not affect dynamic table installation which will install SSDT tables to /sys/firmware/acpi/tables/dynamic. acpi_no_watchdog [HW,ACPI,WDT] Ignore the ACPI-based watchdog interface (WDAT) and let a native driver control the watchdog device instead. acpi_rsdp= [ACPI,EFI,KEXEC,EARLY] Pass the RSDP address to the kernel, mostly used on machines running EFI runtime service to boot the second kernel for kdump. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS Format: To spoof as Windows 98: ="Microsoft Windows" acpi_rev_override [ACPI] Override the _REV object to return 5 (instead of 2 which is mandated by ACPI 6) as the supported ACPI specification revision (when using this switch, it may be necessary to carry out a cold reboot _twice_ in a row to make it take effect on the platform firmware). acpi_osi= [HW,ACPI] Modify list of supported OS interface strings acpi_osi="string1" # add string1 acpi_osi="!string2" # remove string2 acpi_osi=!* # remove all strings acpi_osi=! # disable all built-in OS vendor strings acpi_osi=!! # enable all built-in OS vendor strings acpi_osi= # disable all strings 'acpi_osi=!' can be used in combination with single or multiple 'acpi_osi="string1"' to support specific OS vendor string(s). Note that such command can only affect the default state of the OS vendor strings, thus it cannot affect the default state of the feature group strings and the current state of the OS vendor strings, specifying it multiple times through kernel command line is meaningless. This command is useful when one do not care about the state of the feature group strings which should be controlled by the OSPM. Examples: 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent to 'acpi_osi="Windows 2000" acpi_osi=!', they all can make '_OSI("Windows 2000")' TRUE. 'acpi_osi=' cannot be used in combination with other 'acpi_osi=' command lines, the _OSI method will not exist in the ACPI namespace. NOTE that such command can only affect the _OSI support state, thus specifying it multiple times through kernel command line is also meaningless. Examples: 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' FALSE. 'acpi_osi=!*' can be used in combination with single or multiple 'acpi_osi="string1"' to support specific string(s). Note that such command can affect the current state of both the OS vendor strings and the feature group strings, thus specifying it multiple times through kernel command line is meaningful. But it may still not able to affect the final state of a string if there are quirks related to this string. This command is useful when one want to control the state of the feature group strings to debug BIOS issues related to the OSPM features. Examples: 1. 'acpi_osi="Module Device" acpi_osi=!*' can make '_OSI("Module Device")' FALSE. 2. 'acpi_osi=!* acpi_osi="Module Device"' can make '_OSI("Module Device")' TRUE. 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is equivalent to 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' and 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', they all will make '_OSI("Windows 2000")' TRUE. acpi_pm_good [X86] Override the pmtimer bug detection: force the kernel to assume that this machine's pmtimer latches its value and always returns good values. acpi_sci= [HW,ACPI,EARLY] ACPI System Control Interrupt trigger mode Format: { level | edge | high | low } acpi_skip_timer_override [HW,ACPI,EARLY] Recognize and ignore IRQ0/pin2 Interrupt Override. For broken nForce2 BIOS resulting in XT-PIC timer. acpi_sleep= [HW,ACPI] Sleep options Format: { s3_bios, s3_mode, s3_beep, s4_hwsig, s4_nohwsig, old_ordering, nonvs, sci_force_enable, nobl } See Documentation/power/video.rst for information on s3_bios and s3_mode. s3_beep is for debugging; it makes the PC's speaker beep as soon as the kernel's real-mode entry point is called. s4_hwsig causes the kernel to check the ACPI hardware signature during resume from hibernation, and gracefully refuse to resume if it has changed. This complies with the ACPI specification but not with reality, since Windows does not do this and many laptops do change it on docking. So the default behaviour is to allow resume and simply warn when the signature changes, unless the s4_hwsig option is enabled. s4_nohwsig prevents ACPI hardware signature from being used (or even warned about) during resume. old_ordering causes the ACPI 1.0 ordering of the _PTS control method, with respect to putting devices into low power states, to be enforced (the ACPI 2.0 ordering of _PTS is used by default). nonvs prevents the kernel from saving/restoring the ACPI NVS memory during suspend/hibernation and resume. sci_force_enable causes the kernel to set SCI_EN directly on resume from S1/S3 (which is against the ACPI spec, but some broken systems don't work without it). nobl causes the internal blacklist of systems known to behave incorrectly in some ways with respect to system suspend and resume to be ignored (use wisely). acpi_use_timer_override [HW,ACPI,EARLY] Use timer override. For some broken Nvidia NF5 boards that require a timer override, but don't have HPET add_efi_memmap [EFI,X86,EARLY] Include EFI memory map in kernel's map of available physical RAM. agp= [AGP] { off | try_unsupported } off: disable AGP support try_unsupported: try to drive unsupported chipsets (may crash computer or cause data corruption) ALSA [HW,ALSA] See Documentation/sound/alsa-configuration.rst alignment= [KNL,ARM] Allow the default userspace alignment fault handler behaviour to be specified. Bit 0 enables warnings, bit 1 enables fixups, and bit 2 sends a segfault. align_va_addr= [X86-64] Align virtual addresses by clearing slice [14:12] when allocating a VMA at process creation time. This option gives you up to 3% performance improvement on AMD F15h machines (where it is enabled by default) for a CPU-intensive style benchmark, and it can vary highly in a microbenchmark depending on workload and compiler. 32: only for 32-bit processes 64: only for 64-bit processes on: enable for both 32- and 64-bit processes off: disable for both 32- and 64-bit processes alloc_snapshot [FTRACE] Allocate the ftrace snapshot buffer on boot up when the main buffer is allocated. This is handy if debugging and you need to use tracing_snapshot() on boot up, and do not want to use tracing_snapshot_alloc() as it needs to be done where GFP_KERNEL allocations are allowed. allow_mismatched_32bit_el0 [ARM64,EARLY] Allow execve() of 32-bit applications and setting of the PER_LINUX32 personality on systems where only a strict subset of the CPUs support 32-bit EL0. When this parameter is present, the set of CPUs supporting 32-bit EL0 is indicated by /sys/devices/system/cpu/aarch32_el0 and hot-unplug operations may be restricted. See Documentation/arch/arm64/asymmetric-32bit.rst for more information. amd_iommu= [HW,X86-64] Pass parameters to the AMD IOMMU driver in the system. Possible values are: fullflush - Deprecated, equivalent to iommu.strict=1 off - do not initialize any AMD IOMMU found in the system force_isolation - Force device isolation for all devices. The IOMMU driver is not allowed anymore to lift isolation requirements as needed. This option does not override iommu=pt force_enable - Force enable the IOMMU on platforms known to be buggy with IOMMU enabled. Use this option with care. pgtbl_v1 - Use v1 page table for DMA-API (Default). pgtbl_v2 - Use v2 page table for DMA-API. irtcachedis - Disable Interrupt Remapping Table (IRT) caching. nohugepages - Limit page-sizes used for v1 page-tables to 4 KiB. v2_pgsizes_only - Limit page-sizes used for v1 page-tables to 4KiB/2Mib/1GiB. amd_iommu_dump= [HW,X86-64] Enable AMD IOMMU driver option to dump the ACPI table for AMD IOMMU. With this option enabled, AMD IOMMU driver will print ACPI tables for AMD IOMMU during IOMMU initialization. amd_iommu_intr= [HW,X86-64] Specifies one of the following AMD IOMMU interrupt remapping modes: legacy - Use legacy interrupt remapping mode. vapic - Use virtual APIC mode, which allows IOMMU to inject interrupts directly into guest. This mode requires kvm-amd.avic=1. (Default when IOMMU HW support is present.) amd_pstate= [X86,EARLY] disable Do not enable amd_pstate as the default scaling driver for the supported processors passive Use amd_pstate with passive mode as a scaling driver. In this mode autonomous selection is disabled. Driver requests a desired performance level and platform tries to match the same performance level if it is satisfied by guaranteed performance level. active Use amd_pstate_epp driver instance as the scaling driver, driver provides a hint to the hardware if software wants to bias toward performance (0x0) or energy efficiency (0xff) to the CPPC firmware. then CPPC power algorithm will calculate the runtime workload and adjust the realtime cores frequency. guided Activate guided autonomous mode. Driver requests minimum and maximum performance level and the platform autonomously selects a performance level in this range and appropriate to the current workload. amd_prefcore= [X86] disable Disable amd-pstate preferred core. amijoy.map= [HW,JOY] Amiga joystick support Map of devices attached to JOY0DAT and JOY1DAT Format: <a>,<b> See also Documentation/input/joydev/joystick.rst analog.map= [HW,JOY] Analog joystick and gamepad support Specifies type or capabilities of an analog joystick connected to one of 16 gameports Format: <type1>,<type2>,..<type16> apc= [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.) Format: noidle Disable APC CPU standby support. SPARCstation-Fox does not play well with APC CPU idle - disable it if you have APC and your system crashes randomly. apic= [APIC,X86,EARLY] Advanced Programmable Interrupt Controller Change the output verbosity while booting Format: { quiet (default) | verbose | debug } Change the amount of debugging information output when initialising the APIC and IO-APIC components. For X86-32, this can also be used to specify an APIC driver name. Format: apic=driver_name Examples: apic=bigsmp apic_extnmi= [APIC,X86,EARLY] External NMI delivery setting Format: { bsp (default) | all | none } bsp: External NMI is delivered only to CPU 0 all: External NMIs are broadcast to all CPUs as a backup of CPU 0 none: External NMI is masked for all CPUs. This is useful so that a dump capture kernel won't be shot down by NMI autoconf= [IPV6] See Documentation/networking/ipv6.rst. apm= [APM] Advanced Power Management See header of arch/x86/kernel/apm_32.c. apparmor= [APPARMOR] Disable or enable AppArmor at boot time Format: { "0" | "1" } See security/apparmor/Kconfig help text 0 -- disable. 1 -- enable. Default value is set via kernel config option. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards Format: <io>,<irq>,<nodeID> arm64.no32bit_el0 [ARM64] Unconditionally disable the execution of 32 bit applications. arm64.nobti [ARM64] Unconditionally disable Branch Target Identification support arm64.nogcs [ARM64] Unconditionally disable Guarded Control Stack support arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory Set instructions support arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension support arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication support arm64.nosme [ARM64] Unconditionally disable Scalable Matrix Extension support arm64.nosve [ARM64] Unconditionally disable Scalable Vector Extension support ataflop= [HW,M68k] atarimouse= [HW,MOUSE] Atari Mouse atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, EzKey and similar keyboards atkbd.reset= [HW] Reset keyboard during initialization atkbd.set= [HW] Select keyboard code set Format: <int> (2 = AT (default), 3 = PS/2) atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar keyboards atkbd.softraw= [HW] Choose between synthetic and real raw mode Format: <bool> (0 = real, 1 = synthetic (default)) atkbd.softrepeat= [HW] Use software keyboard repeat audit= [KNL] Enable the audit sub-system Format: { "0" | "1" | "off" | "on" } 0 | off - kernel audit is disabled and can not be enabled until the next reboot unset - kernel audit is initialized but disabled and will be fully enabled by the userspace auditd. 1 | on - kernel audit is initialized and partially enabled, storing at most audit_backlog_limit messages in RAM until it is fully enabled by the userspace auditd. Default: unset audit_backlog_limit= [KNL] Set the audit queue size limit.Lines 1–500 of 7745. Load more
accept_memory= [MM] Format: { eager | lazy } default: lazy By default, unaccepted memory is accepted lazily to avoid prolonged boot times. The lazy option will add some runtime overhead until all memory is eventually accepted. In most cases the overhead is negligible. For some workloads or for debugging purposes accept_memory=eager can be used to accept all memory at once during boot. acpi= [HW,ACPI,X86,ARM64,RISCV64,EARLY] Advanced Configuration and Power Interface Format: { force | on | off | strict | noirq | rsdt | copy_dsdt | nospcr } force -- enable ACPI if default was off on -- enable ACPI but allow fallback to DT [arm64,riscv64] off -- disable ACPI if default was on noirq -- do not use ACPI for IRQ routing strict -- Be less tolerant of platforms that are not strictly ACPI specification compliant. rsdt -- prefer RSDT over (default) XSDT copy_dsdt -- copy DSDT to memory nospcr -- disable console in ACPI SPCR table as default _serial_ console on ARM64 For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or "acpi=nospcr" are available For RISCV64, ONLY "acpi=off", "acpi=on" or "acpi=force" are available See also Documentation/power/runtime_pm.rst, pci=noacpi acpi_apic_instance= [ACPI,IOAPIC,EARLY] Format: <int> 2: use 2nd APIC table, if available 1,0: use 1st APIC table default: 0 acpi_backlight= [HW,ACPI] { vendor | video | native | none } If set to vendor, prefer vendor-specific driver (e.g. thinkpad_acpi, sony_acpi, etc.) instead of the ACPI video.ko driver. If set to video, use the ACPI video.ko driver. If set to native, use the device's native backlight mode. If set to none, disable the ACPI backlight interface. acpi_force_32bit_fadt_addr [ACPI,EARLY] force FADT to use 32 bit addresses rather than the 64 bit X_* addresses. Some firmware have broken 64 bit addresses for force ACPI ignore these and use the older legacy 32 bit addresses. acpica_no_return_repair [HW, ACPI] Disable AML predefined validation mechanism This mechanism can repair the evaluation result to make the return objects more ACPI specification compliant. This option is useful for developers to identify the root cause of an AML interpreter issue when the issue has something to do with the repair mechanism. acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] acpi.debug_level= [HW,ACPI,ACPI_DEBUG] Format: <int> CONFIG_ACPI_DEBUG must be enabled to produce any ACPI debug output. Bits in debug_layer correspond to a _COMPONENT in an ACPI source file, e.g., #define _COMPONENT ACPI_EVENTS Bits in debug_level correspond to a level in ACPI_DEBUG_PRINT statements, e.g., ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... The debug_level mask defaults to "info". See Documentation/firmware-guide/acpi/debug.rst for more information about debug layers and levels. Enable processor driver info messages: acpi.debug_layer=0x20000000 Enable AML "Debug" output, i.e., stores to the Debug object while interpreting AML: acpi.debug_layer=0xffffffff acpi.debug_level=0x2 Enable all messages related to ACPI hardware: acpi.debug_layer=0x2 acpi.debug_level=0xffffffff Some values produce so much output that the system is unusable. The "log_buf_len" parameter may be useful if you need to capture more output. acpi_enforce_resources= [ACPI] { strict | lax | no } Check for resource conflicts between native drivers and ACPI OperationRegions (SystemIO and SystemMemory only). IO ports and memory declared in ACPI might be used by the ACPI subsystem in arbitrary AML code and can interfere with legacy drivers. strict (default): access to resources claimed by ACPI is denied; legacy drivers trying to access reserved resources will fail to bind to device using them. lax: access to resources claimed by ACPI is allowed; legacy drivers trying to access reserved resources will bind successfully but a warning message is logged. no: ACPI OperationRegions are not marked as reserved, no further checks are performed. acpi_force_table_verification [HW,ACPI,EARLY] Enable table checksum verification during early stage. By default, this is disabled due to x86 early mapping size limitation. acpi_irq_balance [HW,ACPI] ACPI will balance active IRQs default in APIC mode acpi_irq_nobalance [HW,ACPI] ACPI will not move active IRQs (default) default in PIC mode acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA Format: <irq>,<irq>... acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for use by PCI Format: <irq>,<irq>... acpi_mask_gpe= [HW,ACPI] Due to the existence of _Lxx/_Exx, some GPEs triggered by unsupported hardware/firmware features can result in GPE floodings that cannot be automatically disabled by the GPE dispatcher. This facility can be used to prevent such uncontrolled GPE floodings. Format: <byte> or <bitmap-list> acpi_no_auto_serialize [HW,ACPI] Disable auto-serialization of AML methods AML control methods that contain the opcodes to create named objects will be marked as "Serialized" by the auto-serialization feature. This feature is enabled by default. This option allows to turn off the feature. acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump kernels. acpi_no_static_ssdt [HW,ACPI,EARLY] Disable installation of static SSDTs at early boot time By default, SSDTs contained in the RSDT/XSDT will be installed automatically and they will appear under /sys/firmware/acpi/tables. This option turns off this feature. Note that specifying this option does not affect dynamic table installation which will install SSDT tables to /sys/firmware/acpi/tables/dynamic. acpi_no_watchdog [HW,ACPI,WDT] Ignore the ACPI-based watchdog interface (WDAT) and let a native driver control the watchdog device instead. acpi_rsdp= [ACPI,EFI,KEXEC,EARLY] Pass the RSDP address to the kernel, mostly used on machines running EFI runtime service to boot the second kernel for kdump. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS Format: To spoof as Windows 98: ="Microsoft Windows" acpi_rev_override [ACPI] Override the _REV object to return 5 (instead of 2 which is mandated by ACPI 6) as the supported ACPI specification revision (when using this switch, it may be necessary to carry out a cold reboot _twice_ in a row to make it take effect on the platform firmware). acpi_osi= [HW,ACPI] Modify list of supported OS interface strings acpi_osi="string1" # add string1 acpi_osi="!string2" # remove string2 acpi_osi=!* # remove all strings acpi_osi=! # disable all built-in OS vendor strings acpi_osi=!! # enable all built-in OS vendor strings acpi_osi= # disable all strings 'acpi_osi=!' can be used in combination with single or multiple 'acpi_osi="string1"' to support specific OS vendor string(s). Note that such command can only affect the default state of the OS vendor strings, thus it cannot affect the default state of the feature group strings and the current state of the OS vendor strings, specifying it multiple times through kernel command line is meaningless. This command is useful when one do not care about the state of the feature group strings which should be controlled by the OSPM. Examples: 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent to 'acpi_osi="Windows 2000" acpi_osi=!', they all can make '_OSI("Windows 2000")' TRUE. 'acpi_osi=' cannot be used in combination with other 'acpi_osi=' command lines, the _OSI method will not exist in the ACPI namespace. NOTE that such command can only affect the _OSI support state, thus specifying it multiple times through kernel command line is also meaningless. Examples: 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' FALSE. 'acpi_osi=!*' can be used in combination with single or multiple 'acpi_osi="string1"' to support specific string(s). Note that such command can affect the current state of both the OS vendor strings and the feature group strings, thus specifying it multiple times through kernel command line is meaningful. But it may still not able to affect the final state of a string if there are quirks related to this string. This command is useful when one want to control the state of the feature group strings to debug BIOS issues related to the OSPM features. Examples: 1. 'acpi_osi="Module Device" acpi_osi=!*' can make '_OSI("Module Device")' FALSE. 2. 'acpi_osi=!* acpi_osi="Module Device"' can make '_OSI("Module Device")' TRUE. 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is equivalent to 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' and 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', they all will make '_OSI("Windows 2000")' TRUE. acpi_pm_good [X86] Override the pmtimer bug detection: force the kernel to assume that this machine's pmtimer latches its value and always returns good values. acpi_sci= [HW,ACPI,EARLY] ACPI System Control Interrupt trigger mode Format: { level | edge | high | low } acpi_skip_timer_override [HW,ACPI,EARLY] Recognize and ignore IRQ0/pin2 Interrupt Override. For broken nForce2 BIOS resulting in XT-PIC timer. acpi_sleep= [HW,ACPI] Sleep options Format: { s3_bios, s3_mode, s3_beep, s4_hwsig, s4_nohwsig, old_ordering, nonvs, sci_force_enable, nobl } See Documentation/power/video.rst for information on s3_bios and s3_mode. s3_beep is for debugging; it makes the PC's speaker beep as soon as the kernel's real-mode entry point is called. s4_hwsig causes the kernel to check the ACPI hardware signature during resume from hibernation, and gracefully refuse to resume if it has changed. This complies with the ACPI specification but not with reality, since Windows does not do this and many laptops do change it on docking. So the default behaviour is to allow resume and simply warn when the signature changes, unless the s4_hwsig option is enabled. s4_nohwsig prevents ACPI hardware signature from being used (or even warned about) during resume. old_ordering causes the ACPI 1.0 ordering of the _PTS control method, with respect to putting devices into low power states, to be enforced (the ACPI 2.0 ordering of _PTS is used by default). nonvs prevents the kernel from saving/restoring the ACPI NVS memory during suspend/hibernation and resume. sci_force_enable causes the kernel to set SCI_EN directly on resume from S1/S3 (which is against the ACPI spec, but some broken systems don't work without it). nobl causes the internal blacklist of systems known to behave incorrectly in some ways with respect to system suspend and resume to be ignored (use wisely). acpi_use_timer_override [HW,ACPI,EARLY] Use timer override. For some broken Nvidia NF5 boards that require a timer override, but don't have HPET add_efi_memmap [EFI,X86,EARLY] Include EFI memory map in kernel's map of available physical RAM. agp= [AGP] { off | try_unsupported } off: disable AGP support try_unsupported: try to drive unsupported chipsets (may crash computer or cause data corruption) ALSA [HW,ALSA] See Documentation/sound/alsa-configuration.rst alignment= [KNL,ARM] Allow the default userspace alignment fault handler behaviour to be specified. Bit 0 enables warnings, bit 1 enables fixups, and bit 2 sends a segfault. align_va_addr= [X86-64] Align virtual addresses by clearing slice [14:12] when allocating a VMA at process creation time. This option gives you up to 3% performance improvement on AMD F15h machines (where it is enabled by default) for a CPU-intensive style benchmark, and it can vary highly in a microbenchmark depending on workload and compiler. 32: only for 32-bit processes 64: only for 64-bit processes on: enable for both 32- and 64-bit processes off: disable for both 32- and 64-bit processes alloc_snapshot [FTRACE] Allocate the ftrace snapshot buffer on boot up when the main buffer is allocated. This is handy if debugging and you need to use tracing_snapshot() on boot up, and do not want to use tracing_snapshot_alloc() as it needs to be done where GFP_KERNEL allocations are allowed. allow_mismatched_32bit_el0 [ARM64,EARLY] Allow execve() of 32-bit applications and setting of the PER_LINUX32 personality on systems where only a strict subset of the CPUs support 32-bit EL0. When this parameter is present, the set of CPUs supporting 32-bit EL0 is indicated by /sys/devices/system/cpu/aarch32_el0 and hot-unplug operations may be restricted. See Documentation/arch/arm64/asymmetric-32bit.rst for more information. amd_iommu= [HW,X86-64] Pass parameters to the AMD IOMMU driver in the system. Possible values are: fullflush - Deprecated, equivalent to iommu.strict=1 off - do not initialize any AMD IOMMU found in the system force_isolation - Force device isolation for all devices. The IOMMU driver is not allowed anymore to lift isolation requirements as needed. This option does not override iommu=pt force_enable - Force enable the IOMMU on platforms known to be buggy with IOMMU enabled. Use this option with care. pgtbl_v1 - Use v1 page table for DMA-API (Default). pgtbl_v2 - Use v2 page table for DMA-API. irtcachedis - Disable Interrupt Remapping Table (IRT) caching. nohugepages - Limit page-sizes used for v1 page-tables to 4 KiB. v2_pgsizes_only - Limit page-sizes used for v1 page-tables to 4KiB/2Mib/1GiB. amd_iommu_dump= [HW,X86-64] Enable AMD IOMMU driver option to dump the ACPI table for AMD IOMMU. With this option enabled, AMD IOMMU driver will print ACPI tables for AMD IOMMU during IOMMU initialization. amd_iommu_intr= [HW,X86-64] Specifies one of the following AMD IOMMU interrupt remapping modes: legacy - Use legacy interrupt remapping mode. vapic - Use virtual APIC mode, which allows IOMMU to inject interrupts directly into guest. This mode requires kvm-amd.avic=1. (Default when IOMMU HW support is present.) amd_pstate= [X86,EARLY] disable Do not enable amd_pstate as the default scaling driver for the supported processors passive Use amd_pstate with passive mode as a scaling driver. In this mode autonomous selection is disabled. Driver requests a desired performance level and platform tries to match the same performance level if it is satisfied by guaranteed performance level. active Use amd_pstate_epp driver instance as the scaling driver, driver provides a hint to the hardware if software wants to bias toward performance (0x0) or energy efficiency (0xff) to the CPPC firmware. then CPPC power algorithm will calculate the runtime workload and adjust the realtime cores frequency. guided Activate guided autonomous mode. Driver requests minimum and maximum performance level and the platform autonomously selects a performance level in this range and appropriate to the current workload. amd_prefcore= [X86] disable Disable amd-pstate preferred core. amijoy.map= [HW,JOY] Amiga joystick support Map of devices attached to JOY0DAT and JOY1DAT Format: <a>,<b> See also Documentation/input/joydev/joystick.rst analog.map= [HW,JOY] Analog joystick and gamepad support Specifies type or capabilities of an analog joystick connected to one of 16 gameports Format: <type1>,<type2>,..<type16> apc= [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.) Format: noidle Disable APC CPU standby support. SPARCstation-Fox does not play well with APC CPU idle - disable it if you have APC and your system crashes randomly. apic= [APIC,X86,EARLY] Advanced Programmable Interrupt Controller Change the output verbosity while booting Format: { quiet (default) | verbose | debug } Change the amount of debugging information output when initialising the APIC and IO-APIC components. For X86-32, this can also be used to specify an APIC driver name. Format: apic=driver_name Examples: apic=bigsmp apic_extnmi= [APIC,X86,EARLY] External NMI delivery setting Format: { bsp (default) | all | none } bsp: External NMI is delivered only to CPU 0 all: External NMIs are broadcast to all CPUs as a backup of CPU 0 none: External NMI is masked for all CPUs. This is useful so that a dump capture kernel won't be shot down by NMI autoconf= [IPV6] See Documentation/networking/ipv6.rst. apm= [APM] Advanced Power Management See header of arch/x86/kernel/apm_32.c. apparmor= [APPARMOR] Disable or enable AppArmor at boot time Format: { "0" | "1" } See security/apparmor/Kconfig help text 0 -- disable. 1 -- enable. Default value is set via kernel config option. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards Format: <io>,<irq>,<nodeID> arm64.no32bit_el0 [ARM64] Unconditionally disable the execution of 32 bit applications. arm64.nobti [ARM64] Unconditionally disable Branch Target Identification support arm64.nogcs [ARM64] Unconditionally disable Guarded Control Stack support arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory Set instructions support arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension support arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication support arm64.nosme [ARM64] Unconditionally disable Scalable Matrix Extension support arm64.nosve [ARM64] Unconditionally disable Scalable Vector Extension support ataflop= [HW,M68k] atarimouse= [HW,MOUSE] Atari Mouse atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, EzKey and similar keyboards atkbd.reset= [HW] Reset keyboard during initialization atkbd.set= [HW] Select keyboard code set Format: <int> (2 = AT (default), 3 = PS/2) atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar keyboards atkbd.softraw= [HW] Choose between synthetic and real raw mode Format: <bool> (0 = real, 1 = synthetic (default)) atkbd.softrepeat= [HW] Use software keyboard repeat audit= [KNL] Enable the audit sub-system Format: { "0" | "1" | "off" | "on" } 0 | off - kernel audit is disabled and can not be enabled until the next reboot unset - kernel audit is initialized but disabled and will be fully enabled by the userspace auditd. 1 | on - kernel audit is initialized and partially enabled, storing at most audit_backlog_limit messages in RAM until it is fully enabled by the userspace auditd. Default: unset audit_backlog_limit= [KNL] Set the audit queue size limit.