1e52347bdSJani Nikula acpi= [HW,ACPI,X86,ARM64] 2e52347bdSJani Nikula Advanced Configuration and Power Interface 3e52347bdSJani Nikula Format: { force | on | off | strict | noirq | rsdt | 4e52347bdSJani Nikula copy_dsdt } 5e52347bdSJani Nikula force -- enable ACPI if default was off 6e52347bdSJani Nikula on -- enable ACPI but allow fallback to DT [arm64] 7e52347bdSJani Nikula off -- disable ACPI if default was on 8e52347bdSJani Nikula noirq -- do not use ACPI for IRQ routing 9e52347bdSJani Nikula strict -- Be less tolerant of platforms that are not 10e52347bdSJani Nikula strictly ACPI specification compliant. 11e52347bdSJani Nikula rsdt -- prefer RSDT over (default) XSDT 12e52347bdSJani Nikula copy_dsdt -- copy DSDT to memory 13e52347bdSJani Nikula For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force" 14e52347bdSJani Nikula are available 15e52347bdSJani Nikula 16151f4e2bSMauro Carvalho Chehab See also Documentation/power/runtime_pm.rst, pci=noacpi 17e52347bdSJani Nikula 18e52347bdSJani Nikula acpi_apic_instance= [ACPI, IOAPIC] 19e52347bdSJani Nikula Format: <int> 20e52347bdSJani Nikula 2: use 2nd APIC table, if available 21e52347bdSJani Nikula 1,0: use 1st APIC table 22e52347bdSJani Nikula default: 0 23e52347bdSJani Nikula 24e52347bdSJani Nikula acpi_backlight= [HW,ACPI] 25e52347bdSJani Nikula acpi_backlight=vendor 26e52347bdSJani Nikula acpi_backlight=video 27e52347bdSJani Nikula If set to vendor, prefer vendor specific driver 28e52347bdSJani Nikula (e.g. thinkpad_acpi, sony_acpi, etc.) instead 29e52347bdSJani Nikula of the ACPI video.ko driver. 30e52347bdSJani Nikula 31e52347bdSJani Nikula acpi_force_32bit_fadt_addr 32e52347bdSJani Nikula force FADT to use 32 bit addresses rather than the 33e52347bdSJani Nikula 64 bit X_* addresses. Some firmware have broken 64 34e52347bdSJani Nikula bit addresses for force ACPI ignore these and use 35e52347bdSJani Nikula the older legacy 32 bit addresses. 36e52347bdSJani Nikula 37e52347bdSJani Nikula acpica_no_return_repair [HW, ACPI] 38e52347bdSJani Nikula Disable AML predefined validation mechanism 39e52347bdSJani Nikula This mechanism can repair the evaluation result to make 40e52347bdSJani Nikula the return objects more ACPI specification compliant. 41e52347bdSJani Nikula This option is useful for developers to identify the 42e52347bdSJani Nikula root cause of an AML interpreter issue when the issue 43e52347bdSJani Nikula has something to do with the repair mechanism. 44e52347bdSJani Nikula 45e52347bdSJani Nikula acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] 46e52347bdSJani Nikula acpi.debug_level= [HW,ACPI,ACPI_DEBUG] 47e52347bdSJani Nikula Format: <int> 48e52347bdSJani Nikula CONFIG_ACPI_DEBUG must be enabled to produce any ACPI 49e52347bdSJani Nikula debug output. Bits in debug_layer correspond to a 50e52347bdSJani Nikula _COMPONENT in an ACPI source file, e.g., 51e52347bdSJani Nikula #define _COMPONENT ACPI_PCI_COMPONENT 52e52347bdSJani Nikula Bits in debug_level correspond to a level in 53e52347bdSJani Nikula ACPI_DEBUG_PRINT statements, e.g., 54e52347bdSJani Nikula ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... 55e52347bdSJani Nikula The debug_level mask defaults to "info". See 56cb1aaebeSMauro Carvalho Chehab Documentation/firmware-guide/acpi/debug.rst for more information about 57e52347bdSJani Nikula debug layers and levels. 58e52347bdSJani Nikula 59e52347bdSJani Nikula Enable processor driver info messages: 60e52347bdSJani Nikula acpi.debug_layer=0x20000000 61e52347bdSJani Nikula Enable PCI/PCI interrupt routing info messages: 62e52347bdSJani Nikula acpi.debug_layer=0x400000 63e52347bdSJani Nikula Enable AML "Debug" output, i.e., stores to the Debug 64e52347bdSJani Nikula object while interpreting AML: 65e52347bdSJani Nikula acpi.debug_layer=0xffffffff acpi.debug_level=0x2 66e52347bdSJani Nikula Enable all messages related to ACPI hardware: 67e52347bdSJani Nikula acpi.debug_layer=0x2 acpi.debug_level=0xffffffff 68e52347bdSJani Nikula 69e52347bdSJani Nikula Some values produce so much output that the system is 70e52347bdSJani Nikula unusable. The "log_buf_len" parameter may be useful 71e52347bdSJani Nikula if you need to capture more output. 72e52347bdSJani Nikula 73e52347bdSJani Nikula acpi_enforce_resources= [ACPI] 74e52347bdSJani Nikula { strict | lax | no } 75e52347bdSJani Nikula Check for resource conflicts between native drivers 76e52347bdSJani Nikula and ACPI OperationRegions (SystemIO and SystemMemory 77e52347bdSJani Nikula only). IO ports and memory declared in ACPI might be 78e52347bdSJani Nikula used by the ACPI subsystem in arbitrary AML code and 79e52347bdSJani Nikula can interfere with legacy drivers. 80e52347bdSJani Nikula strict (default): access to resources claimed by ACPI 81e52347bdSJani Nikula is denied; legacy drivers trying to access reserved 82e52347bdSJani Nikula resources will fail to bind to device using them. 83e52347bdSJani Nikula lax: access to resources claimed by ACPI is allowed; 84e52347bdSJani Nikula legacy drivers trying to access reserved resources 85e52347bdSJani Nikula will bind successfully but a warning message is logged. 86e52347bdSJani Nikula no: ACPI OperationRegions are not marked as reserved, 87e52347bdSJani Nikula no further checks are performed. 88e52347bdSJani Nikula 89e52347bdSJani Nikula acpi_force_table_verification [HW,ACPI] 90e52347bdSJani Nikula Enable table checksum verification during early stage. 91e52347bdSJani Nikula By default, this is disabled due to x86 early mapping 92e52347bdSJani Nikula size limitation. 93e52347bdSJani Nikula 94e52347bdSJani Nikula acpi_irq_balance [HW,ACPI] 95e52347bdSJani Nikula ACPI will balance active IRQs 96e52347bdSJani Nikula default in APIC mode 97e52347bdSJani Nikula 98e52347bdSJani Nikula acpi_irq_nobalance [HW,ACPI] 99e52347bdSJani Nikula ACPI will not move active IRQs (default) 100e52347bdSJani Nikula default in PIC mode 101e52347bdSJani Nikula 102e52347bdSJani Nikula acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA 103e52347bdSJani Nikula Format: <irq>,<irq>... 104e52347bdSJani Nikula 105e52347bdSJani Nikula acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for 106e52347bdSJani Nikula use by PCI 107e52347bdSJani Nikula Format: <irq>,<irq>... 108e52347bdSJani Nikula 1099c4aa1eeSLv Zheng acpi_mask_gpe= [HW,ACPI] 1109c4aa1eeSLv Zheng Due to the existence of _Lxx/_Exx, some GPEs triggered 1119c4aa1eeSLv Zheng by unsupported hardware/firmware features can result in 1129c4aa1eeSLv Zheng GPE floodings that cannot be automatically disabled by 1139c4aa1eeSLv Zheng the GPE dispatcher. 1149c4aa1eeSLv Zheng This facility can be used to prevent such uncontrolled 1159c4aa1eeSLv Zheng GPE floodings. 1169c4aa1eeSLv Zheng Format: <int> 1179c4aa1eeSLv Zheng 118e52347bdSJani Nikula acpi_no_auto_serialize [HW,ACPI] 119e52347bdSJani Nikula Disable auto-serialization of AML methods 120e52347bdSJani Nikula AML control methods that contain the opcodes to create 121e52347bdSJani Nikula named objects will be marked as "Serialized" by the 122e52347bdSJani Nikula auto-serialization feature. 123e52347bdSJani Nikula This feature is enabled by default. 124e52347bdSJani Nikula This option allows to turn off the feature. 125e52347bdSJani Nikula 126e52347bdSJani Nikula acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump 127e52347bdSJani Nikula kernels. 128e52347bdSJani Nikula 129e52347bdSJani Nikula acpi_no_static_ssdt [HW,ACPI] 130e52347bdSJani Nikula Disable installation of static SSDTs at early boot time 131e52347bdSJani Nikula By default, SSDTs contained in the RSDT/XSDT will be 132e52347bdSJani Nikula installed automatically and they will appear under 133e52347bdSJani Nikula /sys/firmware/acpi/tables. 134e52347bdSJani Nikula This option turns off this feature. 135e52347bdSJani Nikula Note that specifying this option does not affect 136e52347bdSJani Nikula dynamic table installation which will install SSDT 137e52347bdSJani Nikula tables to /sys/firmware/acpi/tables/dynamic. 138e52347bdSJani Nikula 139e52347bdSJani Nikula acpi_rsdp= [ACPI,EFI,KEXEC] 140e52347bdSJani Nikula Pass the RSDP address to the kernel, mostly used 141e52347bdSJani Nikula on machines running EFI runtime service to boot the 142e52347bdSJani Nikula second kernel for kdump. 143e52347bdSJani Nikula 144e52347bdSJani Nikula acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS 145e52347bdSJani Nikula Format: To spoof as Windows 98: ="Microsoft Windows" 146e52347bdSJani Nikula 147e52347bdSJani Nikula acpi_rev_override [ACPI] Override the _REV object to return 5 (instead 148e52347bdSJani Nikula of 2 which is mandated by ACPI 6) as the supported ACPI 149e52347bdSJani Nikula specification revision (when using this switch, it may 150e52347bdSJani Nikula be necessary to carry out a cold reboot _twice_ in a 151e52347bdSJani Nikula row to make it take effect on the platform firmware). 152e52347bdSJani Nikula 153e52347bdSJani Nikula acpi_osi= [HW,ACPI] Modify list of supported OS interface strings 154e52347bdSJani Nikula acpi_osi="string1" # add string1 155e52347bdSJani Nikula acpi_osi="!string2" # remove string2 156e52347bdSJani Nikula acpi_osi=!* # remove all strings 157e52347bdSJani Nikula acpi_osi=! # disable all built-in OS vendor 158e52347bdSJani Nikula strings 159e52347bdSJani Nikula acpi_osi=!! # enable all built-in OS vendor 160e52347bdSJani Nikula strings 161e52347bdSJani Nikula acpi_osi= # disable all strings 162e52347bdSJani Nikula 163e52347bdSJani Nikula 'acpi_osi=!' can be used in combination with single or 164e52347bdSJani Nikula multiple 'acpi_osi="string1"' to support specific OS 165e52347bdSJani Nikula vendor string(s). Note that such command can only 166e52347bdSJani Nikula affect the default state of the OS vendor strings, thus 167e52347bdSJani Nikula it cannot affect the default state of the feature group 168e52347bdSJani Nikula strings and the current state of the OS vendor strings, 169e52347bdSJani Nikula specifying it multiple times through kernel command line 170e52347bdSJani Nikula is meaningless. This command is useful when one do not 171e52347bdSJani Nikula care about the state of the feature group strings which 172e52347bdSJani Nikula should be controlled by the OSPM. 173e52347bdSJani Nikula Examples: 174e52347bdSJani Nikula 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent 175e52347bdSJani Nikula to 'acpi_osi="Windows 2000" acpi_osi=!', they all 176e52347bdSJani Nikula can make '_OSI("Windows 2000")' TRUE. 177e52347bdSJani Nikula 178e52347bdSJani Nikula 'acpi_osi=' cannot be used in combination with other 179e52347bdSJani Nikula 'acpi_osi=' command lines, the _OSI method will not 180e52347bdSJani Nikula exist in the ACPI namespace. NOTE that such command can 181e52347bdSJani Nikula only affect the _OSI support state, thus specifying it 182e52347bdSJani Nikula multiple times through kernel command line is also 183e52347bdSJani Nikula meaningless. 184e52347bdSJani Nikula Examples: 185e52347bdSJani Nikula 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' 186e52347bdSJani Nikula FALSE. 187e52347bdSJani Nikula 188e52347bdSJani Nikula 'acpi_osi=!*' can be used in combination with single or 189e52347bdSJani Nikula multiple 'acpi_osi="string1"' to support specific 190e52347bdSJani Nikula string(s). Note that such command can affect the 191e52347bdSJani Nikula current state of both the OS vendor strings and the 192e52347bdSJani Nikula feature group strings, thus specifying it multiple times 193e52347bdSJani Nikula through kernel command line is meaningful. But it may 194e52347bdSJani Nikula still not able to affect the final state of a string if 195e52347bdSJani Nikula there are quirks related to this string. This command 196e52347bdSJani Nikula is useful when one want to control the state of the 197e52347bdSJani Nikula feature group strings to debug BIOS issues related to 198e52347bdSJani Nikula the OSPM features. 199e52347bdSJani Nikula Examples: 200e52347bdSJani Nikula 1. 'acpi_osi="Module Device" acpi_osi=!*' can make 201e52347bdSJani Nikula '_OSI("Module Device")' FALSE. 202e52347bdSJani Nikula 2. 'acpi_osi=!* acpi_osi="Module Device"' can make 203e52347bdSJani Nikula '_OSI("Module Device")' TRUE. 204e52347bdSJani Nikula 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is 205e52347bdSJani Nikula equivalent to 206e52347bdSJani Nikula 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' 207e52347bdSJani Nikula and 208e52347bdSJani Nikula 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', 209e52347bdSJani Nikula they all will make '_OSI("Windows 2000")' TRUE. 210e52347bdSJani Nikula 211e52347bdSJani Nikula acpi_pm_good [X86] 212e52347bdSJani Nikula Override the pmtimer bug detection: force the kernel 213e52347bdSJani Nikula to assume that this machine's pmtimer latches its value 214e52347bdSJani Nikula and always returns good values. 215e52347bdSJani Nikula 216e52347bdSJani Nikula acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode 217e52347bdSJani Nikula Format: { level | edge | high | low } 218e52347bdSJani Nikula 219e52347bdSJani Nikula acpi_skip_timer_override [HW,ACPI] 220e52347bdSJani Nikula Recognize and ignore IRQ0/pin2 Interrupt Override. 221e52347bdSJani Nikula For broken nForce2 BIOS resulting in XT-PIC timer. 222e52347bdSJani Nikula 223e52347bdSJani Nikula acpi_sleep= [HW,ACPI] Sleep options 224e52347bdSJani Nikula Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, 22557044031SRafael J. Wysocki old_ordering, nonvs, sci_force_enable, nobl } 226151f4e2bSMauro Carvalho Chehab See Documentation/power/video.rst for information on 227e52347bdSJani Nikula s3_bios and s3_mode. 228e52347bdSJani Nikula s3_beep is for debugging; it makes the PC's speaker beep 229e52347bdSJani Nikula as soon as the kernel's real-mode entry point is called. 230e52347bdSJani Nikula s4_nohwsig prevents ACPI hardware signature from being 231e52347bdSJani Nikula used during resume from hibernation. 232e52347bdSJani Nikula old_ordering causes the ACPI 1.0 ordering of the _PTS 233e52347bdSJani Nikula control method, with respect to putting devices into 234e52347bdSJani Nikula low power states, to be enforced (the ACPI 2.0 ordering 235e52347bdSJani Nikula of _PTS is used by default). 236e52347bdSJani Nikula nonvs prevents the kernel from saving/restoring the 237e52347bdSJani Nikula ACPI NVS memory during suspend/hibernation and resume. 238e52347bdSJani Nikula sci_force_enable causes the kernel to set SCI_EN directly 239e52347bdSJani Nikula on resume from S1/S3 (which is against the ACPI spec, 240e52347bdSJani Nikula but some broken systems don't work without it). 24157044031SRafael J. Wysocki nobl causes the internal blacklist of systems known to 24257044031SRafael J. Wysocki behave incorrectly in some ways with respect to system 24357044031SRafael J. Wysocki suspend and resume to be ignored (use wisely). 244e52347bdSJani Nikula 245e52347bdSJani Nikula acpi_use_timer_override [HW,ACPI] 246e52347bdSJani Nikula Use timer override. For some broken Nvidia NF5 boards 247e52347bdSJani Nikula that require a timer override, but don't have HPET 248e52347bdSJani Nikula 249e52347bdSJani Nikula add_efi_memmap [EFI; X86] Include EFI memory map in 250e52347bdSJani Nikula kernel's map of available physical RAM. 251e52347bdSJani Nikula 252e52347bdSJani Nikula agp= [AGP] 253e52347bdSJani Nikula { off | try_unsupported } 254e52347bdSJani Nikula off: disable AGP support 255e52347bdSJani Nikula try_unsupported: try to drive unsupported chipsets 256e52347bdSJani Nikula (may crash computer or cause data corruption) 257e52347bdSJani Nikula 258e52347bdSJani Nikula ALSA [HW,ALSA] 2591ca2c806SMauro Carvalho Chehab See Documentation/sound/alsa-configuration.rst 260e52347bdSJani Nikula 261e52347bdSJani Nikula alignment= [KNL,ARM] 262e52347bdSJani Nikula Allow the default userspace alignment fault handler 263e52347bdSJani Nikula behaviour to be specified. Bit 0 enables warnings, 264e52347bdSJani Nikula bit 1 enables fixups, and bit 2 sends a segfault. 265e52347bdSJani Nikula 266e52347bdSJani Nikula align_va_addr= [X86-64] 267e52347bdSJani Nikula Align virtual addresses by clearing slice [14:12] when 268e52347bdSJani Nikula allocating a VMA at process creation time. This option 269e52347bdSJani Nikula gives you up to 3% performance improvement on AMD F15h 270e52347bdSJani Nikula machines (where it is enabled by default) for a 271e52347bdSJani Nikula CPU-intensive style benchmark, and it can vary highly in 272e52347bdSJani Nikula a microbenchmark depending on workload and compiler. 273e52347bdSJani Nikula 274e52347bdSJani Nikula 32: only for 32-bit processes 275e52347bdSJani Nikula 64: only for 64-bit processes 276e52347bdSJani Nikula on: enable for both 32- and 64-bit processes 277e52347bdSJani Nikula off: disable for both 32- and 64-bit processes 278e52347bdSJani Nikula 279e52347bdSJani Nikula alloc_snapshot [FTRACE] 280e52347bdSJani Nikula Allocate the ftrace snapshot buffer on boot up when the 281e52347bdSJani Nikula main buffer is allocated. This is handy if debugging 282e52347bdSJani Nikula and you need to use tracing_snapshot() on boot up, and 283e52347bdSJani Nikula do not want to use tracing_snapshot_alloc() as it needs 284e52347bdSJani Nikula to be done where GFP_KERNEL allocations are allowed. 285e52347bdSJani Nikula 286e52347bdSJani Nikula amd_iommu= [HW,X86-64] 287e52347bdSJani Nikula Pass parameters to the AMD IOMMU driver in the system. 288e52347bdSJani Nikula Possible values are: 289e52347bdSJani Nikula fullflush - enable flushing of IO/TLB entries when 290e52347bdSJani Nikula they are unmapped. Otherwise they are 291e52347bdSJani Nikula flushed before they will be reused, which 292e52347bdSJani Nikula is a lot of faster 293e52347bdSJani Nikula off - do not initialize any AMD IOMMU found in 294e52347bdSJani Nikula the system 295e52347bdSJani Nikula force_isolation - Force device isolation for all 296e52347bdSJani Nikula devices. The IOMMU driver is not 297e52347bdSJani Nikula allowed anymore to lift isolation 298e52347bdSJani Nikula requirements as needed. This option 299e52347bdSJani Nikula does not override iommu=pt 300e52347bdSJani Nikula 301e52347bdSJani Nikula amd_iommu_dump= [HW,X86-64] 302e52347bdSJani Nikula Enable AMD IOMMU driver option to dump the ACPI table 303e52347bdSJani Nikula for AMD IOMMU. With this option enabled, AMD IOMMU 304e52347bdSJani Nikula driver will print ACPI tables for AMD IOMMU during 305e52347bdSJani Nikula IOMMU initialization. 306e52347bdSJani Nikula 307e52347bdSJani Nikula amd_iommu_intr= [HW,X86-64] 308e52347bdSJani Nikula Specifies one of the following AMD IOMMU interrupt 309e52347bdSJani Nikula remapping modes: 310e52347bdSJani Nikula legacy - Use legacy interrupt remapping mode. 311e52347bdSJani Nikula vapic - Use virtual APIC mode, which allows IOMMU 312e52347bdSJani Nikula to inject interrupts directly into guest. 313e52347bdSJani Nikula This mode requires kvm-amd.avic=1. 314e52347bdSJani Nikula (Default when IOMMU HW support is present.) 315e52347bdSJani Nikula 316e52347bdSJani Nikula amijoy.map= [HW,JOY] Amiga joystick support 317e52347bdSJani Nikula Map of devices attached to JOY0DAT and JOY1DAT 318e52347bdSJani Nikula Format: <a>,<b> 3191752118dSTom Saeger See also Documentation/input/joydev/joystick.rst 320e52347bdSJani Nikula 321e52347bdSJani Nikula analog.map= [HW,JOY] Analog joystick and gamepad support 322e52347bdSJani Nikula Specifies type or capabilities of an analog joystick 323e52347bdSJani Nikula connected to one of 16 gameports 324e52347bdSJani Nikula Format: <type1>,<type2>,..<type16> 325e52347bdSJani Nikula 326e52347bdSJani Nikula apc= [HW,SPARC] 327e52347bdSJani Nikula Power management functions (SPARCstation-4/5 + deriv.) 328e52347bdSJani Nikula Format: noidle 329e52347bdSJani Nikula Disable APC CPU standby support. SPARCstation-Fox does 330e52347bdSJani Nikula not play well with APC CPU idle - disable it if you have 331e52347bdSJani Nikula APC and your system crashes randomly. 332e52347bdSJani Nikula 33364e05d11SDou Liyang apic= [APIC,X86] Advanced Programmable Interrupt Controller 334806654a9SWill Deacon Change the output verbosity while booting 335e52347bdSJani Nikula Format: { quiet (default) | verbose | debug } 336e52347bdSJani Nikula Change the amount of debugging information output 337e52347bdSJani Nikula when initialising the APIC and IO-APIC components. 33864e05d11SDou Liyang For X86-32, this can also be used to specify an APIC 33964e05d11SDou Liyang driver name. 34064e05d11SDou Liyang Format: apic=driver_name 34164e05d11SDou Liyang Examples: apic=bigsmp 342e52347bdSJani Nikula 343e52347bdSJani Nikula apic_extnmi= [APIC,X86] External NMI delivery setting 344e52347bdSJani Nikula Format: { bsp (default) | all | none } 345e52347bdSJani Nikula bsp: External NMI is delivered only to CPU 0 346e52347bdSJani Nikula all: External NMIs are broadcast to all CPUs as a 347e52347bdSJani Nikula backup of CPU 0 348e52347bdSJani Nikula none: External NMI is masked for all CPUs. This is 349e52347bdSJani Nikula useful so that a dump capture kernel won't be 350e52347bdSJani Nikula shot down by NMI 351e52347bdSJani Nikula 352e52347bdSJani Nikula autoconf= [IPV6] 353e52347bdSJani Nikula See Documentation/networking/ipv6.txt. 354e52347bdSJani Nikula 355e52347bdSJani Nikula show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller 356e52347bdSJani Nikula Limit apic dumping. The parameter defines the maximal 357e52347bdSJani Nikula number of local apics being dumped. Also it is possible 358e52347bdSJani Nikula to set it to "all" by meaning -- no limit here. 359e52347bdSJani Nikula Format: { 1 (default) | 2 | ... | all }. 360e52347bdSJani Nikula The parameter valid if only apic=debug or 361e52347bdSJani Nikula apic=verbose is specified. 362e52347bdSJani Nikula Example: apic=debug show_lapic=all 363e52347bdSJani Nikula 364e52347bdSJani Nikula apm= [APM] Advanced Power Management 365e52347bdSJani Nikula See header of arch/x86/kernel/apm_32.c. 366e52347bdSJani Nikula 367e52347bdSJani Nikula arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards 368e52347bdSJani Nikula Format: <io>,<irq>,<nodeID> 369e52347bdSJani Nikula 370e52347bdSJani Nikula ataflop= [HW,M68k] 371e52347bdSJani Nikula 372e52347bdSJani Nikula atarimouse= [HW,MOUSE] Atari Mouse 373e52347bdSJani Nikula 374e52347bdSJani Nikula atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, 375e52347bdSJani Nikula EzKey and similar keyboards 376e52347bdSJani Nikula 377e52347bdSJani Nikula atkbd.reset= [HW] Reset keyboard during initialization 378e52347bdSJani Nikula 379e52347bdSJani Nikula atkbd.set= [HW] Select keyboard code set 380e52347bdSJani Nikula Format: <int> (2 = AT (default), 3 = PS/2) 381e52347bdSJani Nikula 382e52347bdSJani Nikula atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar 383e52347bdSJani Nikula keyboards 384e52347bdSJani Nikula 385e52347bdSJani Nikula atkbd.softraw= [HW] Choose between synthetic and real raw mode 386e52347bdSJani Nikula Format: <bool> (0 = real, 1 = synthetic (default)) 387e52347bdSJani Nikula 388e52347bdSJani Nikula atkbd.softrepeat= [HW] 389e52347bdSJani Nikula Use software keyboard repeat 390e52347bdSJani Nikula 391e52347bdSJani Nikula audit= [KNL] Enable the audit sub-system 39211dd2666SGreg Edwards Format: { "0" | "1" | "off" | "on" } 39311dd2666SGreg Edwards 0 | off - kernel audit is disabled and can not be 39411dd2666SGreg Edwards enabled until the next reboot 395e52347bdSJani Nikula unset - kernel audit is initialized but disabled and 396e52347bdSJani Nikula will be fully enabled by the userspace auditd. 39711dd2666SGreg Edwards 1 | on - kernel audit is initialized and partially 39811dd2666SGreg Edwards enabled, storing at most audit_backlog_limit 39911dd2666SGreg Edwards messages in RAM until it is fully enabled by the 40011dd2666SGreg Edwards userspace auditd. 401e52347bdSJani Nikula Default: unset 402e52347bdSJani Nikula 403e52347bdSJani Nikula audit_backlog_limit= [KNL] Set the audit queue size limit. 404e52347bdSJani Nikula Format: <int> (must be >=0) 405e52347bdSJani Nikula Default: 64 406e52347bdSJani Nikula 407e52347bdSJani Nikula bau= [X86_UV] Enable the BAU on SGI UV. The default 408e52347bdSJani Nikula behavior is to disable the BAU (i.e. bau=0). 409e52347bdSJani Nikula Format: { "0" | "1" } 410e52347bdSJani Nikula 0 - Disable the BAU. 411e52347bdSJani Nikula 1 - Enable the BAU. 412e52347bdSJani Nikula unset - Disable the BAU. 413e52347bdSJani Nikula 414e52347bdSJani Nikula baycom_epp= [HW,AX25] 415e52347bdSJani Nikula Format: <io>,<mode> 416e52347bdSJani Nikula 417e52347bdSJani Nikula baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem 418e52347bdSJani Nikula Format: <io>,<mode> 419e52347bdSJani Nikula See header of drivers/net/hamradio/baycom_par.c. 420e52347bdSJani Nikula 421e52347bdSJani Nikula baycom_ser_fdx= [HW,AX25] 422e52347bdSJani Nikula BayCom Serial Port AX.25 Modem (Full Duplex Mode) 423e52347bdSJani Nikula Format: <io>,<irq>,<mode>[,<baud>] 424e52347bdSJani Nikula See header of drivers/net/hamradio/baycom_ser_fdx.c. 425e52347bdSJani Nikula 426e52347bdSJani Nikula baycom_ser_hdx= [HW,AX25] 427e52347bdSJani Nikula BayCom Serial Port AX.25 Modem (Half Duplex Mode) 428e52347bdSJani Nikula Format: <io>,<irq>,<mode> 429e52347bdSJani Nikula See header of drivers/net/hamradio/baycom_ser_hdx.c. 430e52347bdSJani Nikula 431e52347bdSJani Nikula blkdevparts= Manual partition parsing of block device(s) for 432e52347bdSJani Nikula embedded devices based on command line input. 433898bd37aSMauro Carvalho Chehab See Documentation/block/cmdline-partition.rst 434e52347bdSJani Nikula 435e52347bdSJani Nikula boot_delay= Milliseconds to delay each printk during boot. 436e52347bdSJani Nikula Values larger than 10 seconds (10000) are changed to 437e52347bdSJani Nikula no delay (0). 438e52347bdSJani Nikula Format: integer 439e52347bdSJani Nikula 440e52347bdSJani Nikula bootmem_debug [KNL] Enable bootmem allocator debug messages. 441e52347bdSJani Nikula 442e52347bdSJani Nikula bert_disable [ACPI] 443e52347bdSJani Nikula Disable BERT OS support on buggy BIOSes. 444e52347bdSJani Nikula 445e52347bdSJani Nikula bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) 446e52347bdSJani Nikula bttv.radio= Most important insmod options are available as 447e52347bdSJani Nikula kernel args too. 448a405ed85STom Saeger bttv.pll= See Documentation/media/v4l-drivers/bttv.rst 449e52347bdSJani Nikula bttv.tuner= 450e52347bdSJani Nikula 451e52347bdSJani Nikula bulk_remove=off [PPC] This parameter disables the use of the pSeries 452e52347bdSJani Nikula firmware feature for flushing multiple hpte entries 453e52347bdSJani Nikula at a time. 454e52347bdSJani Nikula 455e52347bdSJani Nikula c101= [NET] Moxa C101 synchronous serial card 456e52347bdSJani Nikula 457e52347bdSJani Nikula cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. 458e52347bdSJani Nikula Sometimes CPU hardware bugs make them report the cache 459e52347bdSJani Nikula size incorrectly. The kernel will attempt work arounds 460e52347bdSJani Nikula to fix known problems, but for some CPUs it is not 461e52347bdSJani Nikula possible to determine what the correct size should be. 462e52347bdSJani Nikula This option provides an override for these situations. 463e52347bdSJani Nikula 4643fc46fc9SMartin Kepplinger carrier_timeout= 4653fc46fc9SMartin Kepplinger [NET] Specifies amount of time (in seconds) that 4663fc46fc9SMartin Kepplinger the kernel should wait for a network carrier. By default 4673fc46fc9SMartin Kepplinger it waits 120 seconds. 4683fc46fc9SMartin Kepplinger 469e52347bdSJani Nikula ca_keys= [KEYS] This parameter identifies a specific key(s) on 470e52347bdSJani Nikula the system trusted keyring to be used for certificate 471e52347bdSJani Nikula trust validation. 472e52347bdSJani Nikula format: { id:<keyid> | builtin } 473e52347bdSJani Nikula 474e52347bdSJani Nikula cca= [MIPS] Override the kernel pages' cache coherency 475e52347bdSJani Nikula algorithm. Accepted values range from 0 to 7 476e52347bdSJani Nikula inclusive. See arch/mips/include/asm/pgtable-bits.h 477e52347bdSJani Nikula for platform specific values (SB1, Loongson3 and 478e52347bdSJani Nikula others). 479e52347bdSJani Nikula 480e52347bdSJani Nikula ccw_timeout_log [S390] 4818b4a503dSMauro Carvalho Chehab See Documentation/s390/common_io.rst for details. 482e52347bdSJani Nikula 483e52347bdSJani Nikula cgroup_disable= [KNL] Disable a particular controller 484e52347bdSJani Nikula Format: {name of the controller(s) to disable} 485e52347bdSJani Nikula The effects of cgroup_disable=foo are: 486e52347bdSJani Nikula - foo isn't auto-mounted if you mount all cgroups in 487e52347bdSJani Nikula a single hierarchy 488e52347bdSJani Nikula - foo isn't visible as an individually mountable 489e52347bdSJani Nikula subsystem 490e52347bdSJani Nikula {Currently only "memory" controller deal with this and 491e52347bdSJani Nikula cut the overhead, others just disable the usage. So 492e52347bdSJani Nikula only cgroup_disable=memory is actually worthy} 493e52347bdSJani Nikula 4943fc9c12dSTejun Heo cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1 4953fc9c12dSTejun Heo Format: { { controller | "all" | "named" } 4963fc9c12dSTejun Heo [,{ controller | "all" | "named" }...] } 497e52347bdSJani Nikula Like cgroup_disable, but only applies to cgroup v1; 498e52347bdSJani Nikula the blacklisted controllers remain available in cgroup2. 4993fc9c12dSTejun Heo "all" blacklists all controllers and "named" disables 5003fc9c12dSTejun Heo named mounts. Specifying both "all" and "named" disables 5013fc9c12dSTejun Heo all v1 hierarchies. 502e52347bdSJani Nikula 503e52347bdSJani Nikula cgroup.memory= [KNL] Pass options to the cgroup memory controller. 504e52347bdSJani Nikula Format: <string> 505e52347bdSJani Nikula nosocket -- Disable socket memory accounting. 506e52347bdSJani Nikula nokmem -- Disable kernel memory accounting. 507e52347bdSJani Nikula 508e52347bdSJani Nikula checkreqprot [SELINUX] Set initial checkreqprot flag value. 509e52347bdSJani Nikula Format: { "0" | "1" } 510e52347bdSJani Nikula See security/selinux/Kconfig help text. 511e52347bdSJani Nikula 0 -- check protection applied by kernel (includes 512e52347bdSJani Nikula any implied execute protection). 513e52347bdSJani Nikula 1 -- check protection requested by application. 514e52347bdSJani Nikula Default value is set via a kernel config option. 515e52347bdSJani Nikula Value can be changed at runtime via 516e52347bdSJani Nikula /selinux/checkreqprot. 517e52347bdSJani Nikula 518e52347bdSJani Nikula cio_ignore= [S390] 5198b4a503dSMauro Carvalho Chehab See Documentation/s390/common_io.rst for details. 520e52347bdSJani Nikula clk_ignore_unused 521e52347bdSJani Nikula [CLK] 522e52347bdSJani Nikula Prevents the clock framework from automatically gating 523e52347bdSJani Nikula clocks that have not been explicitly enabled by a Linux 524e52347bdSJani Nikula device driver but are enabled in hardware at reset or 525e52347bdSJani Nikula by the bootloader/firmware. Note that this does not 526e52347bdSJani Nikula force such clocks to be always-on nor does it reserve 527e52347bdSJani Nikula those clocks in any way. This parameter is useful for 528e52347bdSJani Nikula debug and development, but should not be needed on a 529e52347bdSJani Nikula platform with proper driver support. For more 53018bcaa4eSMauro Carvalho Chehab information, see Documentation/driver-api/clk.rst. 531e52347bdSJani Nikula 532e52347bdSJani Nikula clock= [BUGS=X86-32, HW] gettimeofday clocksource override. 533e52347bdSJani Nikula [Deprecated] 534e52347bdSJani Nikula Forces specified clocksource (if available) to be used 535e52347bdSJani Nikula when calculating gettimeofday(). If specified 536e52347bdSJani Nikula clocksource is not available, it defaults to PIT. 537e52347bdSJani Nikula Format: { pit | tsc | cyclone | pmtmr } 538e52347bdSJani Nikula 539e52347bdSJani Nikula clocksource= Override the default clocksource 540e52347bdSJani Nikula Format: <string> 541e52347bdSJani Nikula Override the default clocksource and use the clocksource 542e52347bdSJani Nikula with the name specified. 543e52347bdSJani Nikula Some clocksource names to choose from, depending on 544e52347bdSJani Nikula the platform: 545e52347bdSJani Nikula [all] jiffies (this is the base, fallback clocksource) 546e52347bdSJani Nikula [ACPI] acpi_pm 547e52347bdSJani Nikula [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, 548e52347bdSJani Nikula pxa_timer,timer3,32k_counter,timer0_1 549e52347bdSJani Nikula [X86-32] pit,hpet,tsc; 550e52347bdSJani Nikula scx200_hrt on Geode; cyclone on IBM x440 551e52347bdSJani Nikula [MIPS] MIPS 552e52347bdSJani Nikula [PARISC] cr16 553e52347bdSJani Nikula [S390] tod 554e52347bdSJani Nikula [SH] SuperH 555e52347bdSJani Nikula [SPARC64] tick 556e52347bdSJani Nikula [X86-64] hpet,tsc 557e52347bdSJani Nikula 558e52347bdSJani Nikula clocksource.arm_arch_timer.evtstrm= 559e52347bdSJani Nikula [ARM,ARM64] 560e52347bdSJani Nikula Format: <bool> 561e52347bdSJani Nikula Enable/disable the eventstream feature of the ARM 562e52347bdSJani Nikula architected timer so that code using WFE-based polling 563e52347bdSJani Nikula loops can be debugged more effectively on production 564e52347bdSJani Nikula systems. 565e52347bdSJani Nikula 566e52347bdSJani Nikula clearcpuid=BITNUM [X86] 567e52347bdSJani Nikula Disable CPUID feature X for the kernel. See 568e52347bdSJani Nikula arch/x86/include/asm/cpufeatures.h for the valid bit 569e52347bdSJani Nikula numbers. Note the Linux specific bits are not necessarily 570e52347bdSJani Nikula stable over kernel options, but the vendor specific 571e52347bdSJani Nikula ones should be. 572e52347bdSJani Nikula Also note that user programs calling CPUID directly 573e52347bdSJani Nikula or using the feature without checking anything 574e52347bdSJani Nikula will still see it. This just prevents it from 575e52347bdSJani Nikula being used by the kernel or shown in /proc/cpuinfo. 576e52347bdSJani Nikula Also note the kernel might malfunction if you disable 577e52347bdSJani Nikula some critical bits. 578e52347bdSJani Nikula 579e52347bdSJani Nikula cma=nn[MG]@[start[MG][-end[MG]]] 580e52347bdSJani Nikula [ARM,X86,KNL] 581e52347bdSJani Nikula Sets the size of kernel global memory area for 582e52347bdSJani Nikula contiguous memory allocations and optionally the 583e52347bdSJani Nikula placement constraint by the physical address range of 584e52347bdSJani Nikula memory allocations. A value of 0 disables CMA 585e52347bdSJani Nikula altogether. For more information, see 586e52347bdSJani Nikula include/linux/dma-contiguous.h 587e52347bdSJani Nikula 588e52347bdSJani Nikula cmo_free_hint= [PPC] Format: { yes | no } 589e52347bdSJani Nikula Specify whether pages are marked as being inactive 590e52347bdSJani Nikula when they are freed. This is used in CMO environments 591e52347bdSJani Nikula to determine OS memory pressure for page stealing by 592e52347bdSJani Nikula a hypervisor. 593e52347bdSJani Nikula Default: yes 594e52347bdSJani Nikula 595e52347bdSJani Nikula coherent_pool=nn[KMG] [ARM,KNL] 596e52347bdSJani Nikula Sets the size of memory pool for coherent, atomic dma 597e52347bdSJani Nikula allocations, by default set to 256K. 598e52347bdSJani Nikula 599e52347bdSJani Nikula com20020= [HW,NET] ARCnet - COM20020 chipset 600e52347bdSJani Nikula Format: 601e52347bdSJani Nikula <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 602e52347bdSJani Nikula 603e52347bdSJani Nikula com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) 604e52347bdSJani Nikula Format: <io>[,<irq>] 605e52347bdSJani Nikula 606e52347bdSJani Nikula com90xx= [HW,NET] 607e52347bdSJani Nikula ARCnet - COM90xx chipset (memory-mapped buffers) 608e52347bdSJani Nikula Format: <io>[,<irq>[,<memstart>]] 609e52347bdSJani Nikula 610e52347bdSJani Nikula condev= [HW,S390] console device 611e52347bdSJani Nikula conmode= 612e52347bdSJani Nikula 613e52347bdSJani Nikula console= [KNL] Output console device and options. 614e52347bdSJani Nikula 615e52347bdSJani Nikula tty<n> Use the virtual console device <n>. 616e52347bdSJani Nikula 617e52347bdSJani Nikula ttyS<n>[,options] 618e52347bdSJani Nikula ttyUSB0[,options] 619e52347bdSJani Nikula Use the specified serial port. The options are of 620e52347bdSJani Nikula the form "bbbbpnf", where "bbbb" is the baud rate, 621e52347bdSJani Nikula "p" is parity ("n", "o", or "e"), "n" is number of 622e52347bdSJani Nikula bits, and "f" is flow control ("r" for RTS or 623e52347bdSJani Nikula omit it). Default is "9600n8". 624e52347bdSJani Nikula 625e52347bdSJani Nikula See Documentation/admin-guide/serial-console.rst for more 626e52347bdSJani Nikula information. See 627e52347bdSJani Nikula Documentation/networking/netconsole.txt for an 628e52347bdSJani Nikula alternative. 629e52347bdSJani Nikula 630e52347bdSJani Nikula uart[8250],io,<addr>[,options] 631e52347bdSJani Nikula uart[8250],mmio,<addr>[,options] 632e52347bdSJani Nikula uart[8250],mmio16,<addr>[,options] 633e52347bdSJani Nikula uart[8250],mmio32,<addr>[,options] 634e52347bdSJani Nikula uart[8250],0x<addr>[,options] 635e52347bdSJani Nikula Start an early, polled-mode console on the 8250/16550 636e52347bdSJani Nikula UART at the specified I/O port or MMIO address, 637e52347bdSJani Nikula switching to the matching ttyS device later. 638e52347bdSJani Nikula MMIO inter-register address stride is either 8-bit 639e52347bdSJani Nikula (mmio), 16-bit (mmio16), or 32-bit (mmio32). 640e52347bdSJani Nikula If none of [io|mmio|mmio16|mmio32], <addr> is assumed 641e52347bdSJani Nikula to be equivalent to 'mmio'. 'options' are specified in 642e52347bdSJani Nikula the same format described for ttyS above; if unspecified, 643e52347bdSJani Nikula the h/w is not re-initialized. 644e52347bdSJani Nikula 645e52347bdSJani Nikula hvc<n> Use the hypervisor console device <n>. This is for 646e52347bdSJani Nikula both Xen and PowerPC hypervisors. 647e52347bdSJani Nikula 648e52347bdSJani Nikula If the device connected to the port is not a TTY but a braille 649e52347bdSJani Nikula device, prepend "brl," before the device type, for instance 650e52347bdSJani Nikula console=brl,ttyS0 651e52347bdSJani Nikula For now, only VisioBraille is supported. 652e52347bdSJani Nikula 653cca10d58SSergey Senozhatsky console_msg_format= 654cca10d58SSergey Senozhatsky [KNL] Change console messages format 655cca10d58SSergey Senozhatsky default 656cca10d58SSergey Senozhatsky By default we print messages on consoles in 657cca10d58SSergey Senozhatsky "[time stamp] text\n" format (time stamp may not be 658cca10d58SSergey Senozhatsky printed, depending on CONFIG_PRINTK_TIME or 659cca10d58SSergey Senozhatsky `printk_time' param). 660cca10d58SSergey Senozhatsky syslog 661cca10d58SSergey Senozhatsky Switch to syslog format: "<%u>[time stamp] text\n" 662cca10d58SSergey Senozhatsky IOW, each message will have a facility and loglevel 663cca10d58SSergey Senozhatsky prefix. The format is similar to one used by syslog() 664cca10d58SSergey Senozhatsky syscall, or to executing "dmesg -S --raw" or to reading 665cca10d58SSergey Senozhatsky from /proc/kmsg. 666cca10d58SSergey Senozhatsky 667e52347bdSJani Nikula consoleblank= [KNL] The console blank (screen saver) timeout in 668ac0a314cSDaniel Xu seconds. A value of 0 disables the blank timer. 669ac0a314cSDaniel Xu Defaults to 0. 670e52347bdSJani Nikula 671e52347bdSJani Nikula coredump_filter= 672e52347bdSJani Nikula [KNL] Change the default value for 673e52347bdSJani Nikula /proc/<pid>/coredump_filter. 674e52347bdSJani Nikula See also Documentation/filesystems/proc.txt. 675e52347bdSJani Nikula 67662a31ce1SLeo Yan coresight_cpu_debug.enable 67762a31ce1SLeo Yan [ARM,ARM64] 67862a31ce1SLeo Yan Format: <bool> 67962a31ce1SLeo Yan Enable/disable the CPU sampling based debugging. 68062a31ce1SLeo Yan 0: default value, disable debugging 68162a31ce1SLeo Yan 1: enable debugging at boot time 68262a31ce1SLeo Yan 683e52347bdSJani Nikula cpuidle.off=1 [CPU_IDLE] 684e52347bdSJani Nikula disable the cpuidle sub-system 685e52347bdSJani Nikula 68661cb5758SRafael J. Wysocki cpuidle.governor= 68761cb5758SRafael J. Wysocki [CPU_IDLE] Name of the cpuidle governor to use. 68861cb5758SRafael J. Wysocki 689d82f2692SLen Brown cpufreq.off=1 [CPU_FREQ] 690d82f2692SLen Brown disable the cpufreq sub-system 691d82f2692SLen Brown 692e52347bdSJani Nikula cpu_init_udelay=N 693e52347bdSJani Nikula [X86] Delay for N microsec between assert and de-assert 694e52347bdSJani Nikula of APIC INIT to start processors. This delay occurs 695e52347bdSJani Nikula on every CPU online, such as boot, and resume from suspend. 696e52347bdSJani Nikula Default: 10000 697e52347bdSJani Nikula 698e52347bdSJani Nikula cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 699e52347bdSJani Nikula Format: 700e52347bdSJani Nikula <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 701e52347bdSJani Nikula 702e52347bdSJani Nikula crashkernel=size[KMG][@offset[KMG]] 703e52347bdSJani Nikula [KNL] Using kexec, Linux can switch to a 'crash kernel' 704e52347bdSJani Nikula upon panic. This parameter reserves the physical 705e52347bdSJani Nikula memory region [offset, offset + size] for that kernel 706e52347bdSJani Nikula image. If '@offset' is omitted, then a suitable offset 707b9ac3849SDave Young is selected automatically. 708b9ac3849SDave Young [KNL, x86_64] select a region under 4G first, and 709b9ac3849SDave Young fall back to reserve region above 4G when '@offset' 710b9ac3849SDave Young hasn't been specified. 711330d4810SMauro Carvalho Chehab See Documentation/admin-guide/kdump/kdump.rst for further details. 712e52347bdSJani Nikula 713e52347bdSJani Nikula crashkernel=range1:size1[,range2:size2,...][@offset] 714e52347bdSJani Nikula [KNL] Same as above, but depends on the memory 715e52347bdSJani Nikula in the running system. The syntax of range is 716e52347bdSJani Nikula start-[end] where start and end are both 717e52347bdSJani Nikula a memory unit (amount[KMG]). See also 718330d4810SMauro Carvalho Chehab Documentation/admin-guide/kdump/kdump.rst for an example. 719e52347bdSJani Nikula 720e52347bdSJani Nikula crashkernel=size[KMG],high 721e52347bdSJani Nikula [KNL, x86_64] range could be above 4G. Allow kernel 722e52347bdSJani Nikula to allocate physical memory region from top, so could 723e52347bdSJani Nikula be above 4G if system have more than 4G ram installed. 724e52347bdSJani Nikula Otherwise memory region will be allocated below 4G, if 725e52347bdSJani Nikula available. 726e52347bdSJani Nikula It will be ignored if crashkernel=X is specified. 727e52347bdSJani Nikula crashkernel=size[KMG],low 728e52347bdSJani Nikula [KNL, x86_64] range under 4G. When crashkernel=X,high 729e52347bdSJani Nikula is passed, kernel could allocate physical memory region 730e52347bdSJani Nikula above 4G, that cause second kernel crash on system 731e52347bdSJani Nikula that require some amount of low memory, e.g. swiotlb 732e52347bdSJani Nikula requires at least 64M+32K low memory, also enough extra 733e52347bdSJani Nikula low memory is needed to make sure DMA buffers for 32-bit 734e52347bdSJani Nikula devices won't run out. Kernel would try to allocate at 735e52347bdSJani Nikula at least 256M below 4G automatically. 736e52347bdSJani Nikula This one let user to specify own low range under 4G 737e52347bdSJani Nikula for second kernel instead. 738e52347bdSJani Nikula 0: to disable low allocation. 739e52347bdSJani Nikula It will be ignored when crashkernel=X,high is not used 740e52347bdSJani Nikula or memory reserved is below 4G. 741e52347bdSJani Nikula 742e52347bdSJani Nikula cryptomgr.notests 743e52347bdSJani Nikula [KNL] Disable crypto self-tests 744e52347bdSJani Nikula 745e52347bdSJani Nikula cs89x0_dma= [HW,NET] 746e52347bdSJani Nikula Format: <dma> 747e52347bdSJani Nikula 748e52347bdSJani Nikula cs89x0_media= [HW,NET] 749e52347bdSJani Nikula Format: { rj45 | aui | bnc } 750e52347bdSJani Nikula 751e52347bdSJani Nikula dasd= [HW,NET] 752e52347bdSJani Nikula See header of drivers/s390/block/dasd_devmap.c. 753e52347bdSJani Nikula 754e52347bdSJani Nikula db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port 755e52347bdSJani Nikula (one device per port) 756e52347bdSJani Nikula Format: <port#>,<type> 7571752118dSTom Saeger See also Documentation/input/devices/joystick-parport.rst 758e52347bdSJani Nikula 759e52347bdSJani Nikula ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot 760787e3075SSteffen Maier time. See 761787e3075SSteffen Maier Documentation/admin-guide/dynamic-debug-howto.rst for 762e52347bdSJani Nikula details. Deprecated, see dyndbg. 763e52347bdSJani Nikula 764e52347bdSJani Nikula debug [KNL] Enable kernel debugging (events log level). 765e52347bdSJani Nikula 7663672476eSTobin C. Harding debug_boot_weak_hash 7673672476eSTobin C. Harding [KNL] Enable printing [hashed] pointers early in the 7683672476eSTobin C. Harding boot sequence. If enabled, we use a weak hash instead 7693672476eSTobin C. Harding of siphash to hash pointers. Use this option if you are 7703672476eSTobin C. Harding seeing instances of '(___ptrval___)') and need to see a 7713672476eSTobin C. Harding value (hashed pointer) instead. Cryptographically 7723672476eSTobin C. Harding insecure, please do not use on production kernels. 7733672476eSTobin C. Harding 774e52347bdSJani Nikula debug_locks_verbose= 775e52347bdSJani Nikula [KNL] verbose self-tests 776e52347bdSJani Nikula Format=<0|1> 777e52347bdSJani Nikula Print debugging info while doing the locking API 778e52347bdSJani Nikula self-tests. 779e52347bdSJani Nikula We default to 0 (no extra messages), setting it to 780e52347bdSJani Nikula 1 will print _a lot_ more information - normally 781e52347bdSJani Nikula only useful to kernel developers. 782e52347bdSJani Nikula 783e52347bdSJani Nikula debug_objects [KNL] Enable object debugging 784e52347bdSJani Nikula 785e52347bdSJani Nikula no_debug_objects 786e52347bdSJani Nikula [KNL] Disable object debugging 787e52347bdSJani Nikula 788e52347bdSJani Nikula debug_guardpage_minorder= 789e52347bdSJani Nikula [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this 790e52347bdSJani Nikula parameter allows control of the order of pages that will 791e52347bdSJani Nikula be intentionally kept free (and hence protected) by the 792e52347bdSJani Nikula buddy allocator. Bigger value increase the probability 793e52347bdSJani Nikula of catching random memory corruption, but reduce the 794e52347bdSJani Nikula amount of memory for normal system use. The maximum 795e52347bdSJani Nikula possible value is MAX_ORDER/2. Setting this parameter 796e52347bdSJani Nikula to 1 or 2 should be enough to identify most random 797e52347bdSJani Nikula memory corruption problems caused by bugs in kernel or 798e52347bdSJani Nikula driver code when a CPU writes to (or reads from) a 799e52347bdSJani Nikula random memory location. Note that there exists a class 800e52347bdSJani Nikula of memory corruptions problems caused by buggy H/W or 801e52347bdSJani Nikula F/W or by drivers badly programing DMA (basically when 802e52347bdSJani Nikula memory is written at bus level and the CPU MMU is 803e52347bdSJani Nikula bypassed) which are not detectable by 804e52347bdSJani Nikula CONFIG_DEBUG_PAGEALLOC, hence this option will not help 805e52347bdSJani Nikula tracking down these problems. 806e52347bdSJani Nikula 807e52347bdSJani Nikula debug_pagealloc= 8083972f6bbSVlastimil Babka [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this parameter 8093972f6bbSVlastimil Babka enables the feature at boot time. By default, it is 8103972f6bbSVlastimil Babka disabled and the system will work mostly the same as a 8113972f6bbSVlastimil Babka kernel built without CONFIG_DEBUG_PAGEALLOC. 8128974558fSVlastimil Babka Note: to get most of debug_pagealloc error reports, it's 8138974558fSVlastimil Babka useful to also enable the page_owner functionality. 814e52347bdSJani Nikula on: enable the feature 815e52347bdSJani Nikula 816e52347bdSJani Nikula debugpat [X86] Enable PAT debugging 817e52347bdSJani Nikula 818e52347bdSJani Nikula decnet.addr= [HW,NET] 819e52347bdSJani Nikula Format: <area>[,<node>] 820e52347bdSJani Nikula See also Documentation/networking/decnet.txt. 821e52347bdSJani Nikula 822e52347bdSJani Nikula default_hugepagesz= 823e52347bdSJani Nikula [same as hugepagesz=] The size of the default 824e52347bdSJani Nikula HugeTLB page size. This is the size represented by 825e52347bdSJani Nikula the legacy /proc/ hugepages APIs, used for SHM, and 826e52347bdSJani Nikula default size when mounting hugetlbfs filesystems. 827e52347bdSJani Nikula Defaults to the default architecture's huge page size 828e52347bdSJani Nikula if not specified. 829e52347bdSJani Nikula 83025b4e70dSRob Herring deferred_probe_timeout= 83125b4e70dSRob Herring [KNL] Debugging option to set a timeout in seconds for 83225b4e70dSRob Herring deferred probe to give up waiting on dependencies to 83325b4e70dSRob Herring probe. Only specific dependencies (subsystems or 83425b4e70dSRob Herring drivers) that have opted in will be ignored. A timeout of 0 83525b4e70dSRob Herring will timeout at the end of initcalls. This option will also 83625b4e70dSRob Herring dump out devices still on the deferred probe list after 83725b4e70dSRob Herring retrying. 83825b4e70dSRob Herring 839e52347bdSJani Nikula dhash_entries= [KNL] 840e52347bdSJani Nikula Set number of hash buckets for dentry cache. 841e52347bdSJani Nikula 842e52347bdSJani Nikula disable_1tb_segments [PPC] 843e52347bdSJani Nikula Disables the use of 1TB hash page table segments. This 844e52347bdSJani Nikula causes the kernel to fall back to 256MB segments which 845e52347bdSJani Nikula can be useful when debugging issues that require an SLB 846e52347bdSJani Nikula miss to occur. 847e52347bdSJani Nikula 848e52347bdSJani Nikula disable= [IPV6] 849e52347bdSJani Nikula See Documentation/networking/ipv6.txt. 850e52347bdSJani Nikula 851b5cb15d9SChris von Recklinghausen hardened_usercopy= 852b5cb15d9SChris von Recklinghausen [KNL] Under CONFIG_HARDENED_USERCOPY, whether 853b5cb15d9SChris von Recklinghausen hardening is enabled for this boot. Hardened 854b5cb15d9SChris von Recklinghausen usercopy checking is used to protect the kernel 855b5cb15d9SChris von Recklinghausen from reading or writing beyond known memory 856b5cb15d9SChris von Recklinghausen allocation boundaries as a proactive defense 857b5cb15d9SChris von Recklinghausen against bounds-checking flaws in the kernel's 858b5cb15d9SChris von Recklinghausen copy_to_user()/copy_from_user() interface. 859b5cb15d9SChris von Recklinghausen on Perform hardened usercopy checks (default). 860b5cb15d9SChris von Recklinghausen off Disable hardened usercopy checks. 861b5cb15d9SChris von Recklinghausen 862e52347bdSJani Nikula disable_radix [PPC] 863e52347bdSJani Nikula Disable RADIX MMU mode on POWER9 864e52347bdSJani Nikula 8652275d7b5SNicholas Piggin disable_tlbie [PPC] 8662275d7b5SNicholas Piggin Disable TLBIE instruction. Currently does not work 8672275d7b5SNicholas Piggin with KVM, with HASH MMU, or with coherent accelerators. 8682275d7b5SNicholas Piggin 869e52347bdSJani Nikula disable_cpu_apicid= [X86,APIC,SMP] 870e52347bdSJani Nikula Format: <int> 871e52347bdSJani Nikula The number of initial APIC ID for the 872e52347bdSJani Nikula corresponding CPU to be disabled at boot, 873e52347bdSJani Nikula mostly used for the kdump 2nd kernel to 874e52347bdSJani Nikula disable BSP to wake up multiple CPUs without 875e52347bdSJani Nikula causing system reset or hang due to sending 876e52347bdSJani Nikula INIT from AP to BSP. 877e52347bdSJani Nikula 8782a5bf23dSPeter Zijlstra perf_v4_pmi= [X86,INTEL] 8792a5bf23dSPeter Zijlstra Format: <bool> 880af3bdb99SAndi Kleen Disable Intel PMU counter freezing feature. 881af3bdb99SAndi Kleen The feature only exists starting from 882af3bdb99SAndi Kleen Arch Perfmon v4 (Skylake and newer). 883af3bdb99SAndi Kleen 884e52347bdSJani Nikula disable_ddw [PPC/PSERIES] 885e52347bdSJani Nikula Disable Dynamic DMA Window support. Use this if 886e52347bdSJani Nikula to workaround buggy firmware. 887e52347bdSJani Nikula 888e52347bdSJani Nikula disable_ipv6= [IPV6] 889e52347bdSJani Nikula See Documentation/networking/ipv6.txt. 890e52347bdSJani Nikula 891e52347bdSJani Nikula disable_mtrr_cleanup [X86] 892e52347bdSJani Nikula The kernel tries to adjust MTRR layout from continuous 893e52347bdSJani Nikula to discrete, to make X server driver able to add WB 894e52347bdSJani Nikula entry later. This parameter disables that. 895e52347bdSJani Nikula 896e52347bdSJani Nikula disable_mtrr_trim [X86, Intel and AMD only] 897e52347bdSJani Nikula By default the kernel will trim any uncacheable 898e52347bdSJani Nikula memory out of your available memory pool based on 899e52347bdSJani Nikula MTRR settings. This parameter disables that behavior, 900e52347bdSJani Nikula possibly causing your machine to run very slowly. 901e52347bdSJani Nikula 902e52347bdSJani Nikula disable_timer_pin_1 [X86] 903e52347bdSJani Nikula Disable PIN 1 of APIC timer 904e52347bdSJani Nikula Can be useful to work around chipset bugs. 905e52347bdSJani Nikula 906e52347bdSJani Nikula dis_ucode_ldr [X86] Disable the microcode loader. 907e52347bdSJani Nikula 908e52347bdSJani Nikula dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, 909e52347bdSJani Nikula this option disables the debugging code at boot. 910e52347bdSJani Nikula 911e52347bdSJani Nikula dma_debug_entries=<number> 912e52347bdSJani Nikula This option allows to tune the number of preallocated 913e52347bdSJani Nikula entries for DMA-API debugging code. One entry is 914e52347bdSJani Nikula required per DMA-API allocation. Use this if the 915e52347bdSJani Nikula DMA-API debugging code disables itself because the 916e52347bdSJani Nikula architectural default is too low. 917e52347bdSJani Nikula 918e52347bdSJani Nikula dma_debug_driver=<driver_name> 919e52347bdSJani Nikula With this option the DMA-API debugging driver 920e52347bdSJani Nikula filter feature can be enabled at boot time. Just 921e52347bdSJani Nikula pass the driver to filter for as the parameter. 922e52347bdSJani Nikula The filter can be disabled or changed to another 923e52347bdSJani Nikula driver later using sysfs. 924e52347bdSJani Nikula 9251ea61b68SFeng Tang driver_async_probe= [KNL] 9261ea61b68SFeng Tang List of driver names to be probed asynchronously. 9271ea61b68SFeng Tang Format: <driver_name1>,<driver_name2>... 9281ea61b68SFeng Tang 92953fd40a9SJani Nikula drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] 930e52347bdSJani Nikula Broken monitors, graphic adapters, KVMs and EDIDless 931e52347bdSJani Nikula panels may send no or incorrect EDID data sets. 932e52347bdSJani Nikula This parameter allows to specify an EDID data sets 933e52347bdSJani Nikula in the /lib/firmware directory that are used instead. 934e52347bdSJani Nikula Generic built-in EDID data sets are used, if one of 935e52347bdSJani Nikula edid/1024x768.bin, edid/1280x1024.bin, 936e52347bdSJani Nikula edid/1680x1050.bin, or edid/1920x1080.bin is given 937e52347bdSJani Nikula and no file with the same name exists. Details and 938e52347bdSJani Nikula instructions how to build your own EDID data are 939baa293e9SMauro Carvalho Chehab available in Documentation/driver-api/edid.rst. An EDID 940e52347bdSJani Nikula data set will only be used for a particular connector, 941e52347bdSJani Nikula if its name and a colon are prepended to the EDID 942e52347bdSJani Nikula name. Each connector may use a unique EDID data 943e52347bdSJani Nikula set by separating the files with a comma. An EDID 944e52347bdSJani Nikula data set with no connector name will be used for 945e52347bdSJani Nikula any connectors not explicitly specified. 946e52347bdSJani Nikula 947e52347bdSJani Nikula dscc4.setup= [NET] 948e52347bdSJani Nikula 949a2b05b7aSNicholas Piggin dt_cpu_ftrs= [PPC] 950a2b05b7aSNicholas Piggin Format: {"off" | "known"} 951a2b05b7aSNicholas Piggin Control how the dt_cpu_ftrs device-tree binding is 952a2b05b7aSNicholas Piggin used for CPU feature discovery and setup (if it 953a2b05b7aSNicholas Piggin exists). 954a2b05b7aSNicholas Piggin off: Do not use it, fall back to legacy cpu table. 955a2b05b7aSNicholas Piggin known: Do not pass through unknown features to guests 956a2b05b7aSNicholas Piggin or userspace, only those that the kernel is aware of. 957a2b05b7aSNicholas Piggin 958e7aa8c2eSLinus Torvalds dump_apple_properties [X86] 959e7aa8c2eSLinus Torvalds Dump name and content of EFI device properties on 960e7aa8c2eSLinus Torvalds x86 Macs. Useful for driver authors to determine 961e7aa8c2eSLinus Torvalds what data is available or for reverse-engineering. 962e7aa8c2eSLinus Torvalds 963e52347bdSJani Nikula dyndbg[="val"] [KNL,DYNAMIC_DEBUG] 964e52347bdSJani Nikula module.dyndbg[="val"] 965e52347bdSJani Nikula Enable debug messages at boot time. See 966787e3075SSteffen Maier Documentation/admin-guide/dynamic-debug-howto.rst 967787e3075SSteffen Maier for details. 968e52347bdSJani Nikula 969e52347bdSJani Nikula nompx [X86] Disables Intel Memory Protection Extensions. 970cb1aaebeSMauro Carvalho Chehab See Documentation/x86/intel_mpx.rst for more 971e52347bdSJani Nikula information about the feature. 972e52347bdSJani Nikula 973e52347bdSJani Nikula nopku [X86] Disable Memory Protection Keys CPU feature found 974e52347bdSJani Nikula in some Intel CPUs. 975e52347bdSJani Nikula 976e52347bdSJani Nikula module.async_probe [KNL] 977e52347bdSJani Nikula Enable asynchronous probe on this module. 978e52347bdSJani Nikula 979e52347bdSJani Nikula early_ioremap_debug [KNL] 980e52347bdSJani Nikula Enable debug messages in early_ioremap support. This 981e52347bdSJani Nikula is useful for tracking down temporary early mappings 982e52347bdSJani Nikula which are not unmapped. 983e52347bdSJani Nikula 984e52347bdSJani Nikula earlycon= [KNL] Output early console device and options. 985e52347bdSJani Nikula 9860231d000SPrarit Bhargava [ARM64] The early console is determined by the 9870231d000SPrarit Bhargava stdout-path property in device tree's chosen node, 9880231d000SPrarit Bhargava or determined by the ACPI SPCR table. 9890231d000SPrarit Bhargava 9900231d000SPrarit Bhargava [X86] When used with no options the early console is 9910231d000SPrarit Bhargava determined by the ACPI SPCR table. 992e52347bdSJani Nikula 993e52347bdSJani Nikula cdns,<addr>[,options] 994e52347bdSJani Nikula Start an early, polled-mode console on a Cadence 995e52347bdSJani Nikula (xuartps) serial port at the specified address. Only 996e52347bdSJani Nikula supported option is baud rate. If baud rate is not 997e52347bdSJani Nikula specified, the serial port must already be setup and 998e52347bdSJani Nikula configured. 999e52347bdSJani Nikula 1000e52347bdSJani Nikula uart[8250],io,<addr>[,options] 1001e52347bdSJani Nikula uart[8250],mmio,<addr>[,options] 1002e52347bdSJani Nikula uart[8250],mmio32,<addr>[,options] 1003e52347bdSJani Nikula uart[8250],mmio32be,<addr>[,options] 1004e52347bdSJani Nikula uart[8250],0x<addr>[,options] 1005e52347bdSJani Nikula Start an early, polled-mode console on the 8250/16550 1006e52347bdSJani Nikula UART at the specified I/O port or MMIO address. 1007e52347bdSJani Nikula MMIO inter-register address stride is either 8-bit 1008e52347bdSJani Nikula (mmio) or 32-bit (mmio32 or mmio32be). 1009e52347bdSJani Nikula If none of [io|mmio|mmio32|mmio32be], <addr> is assumed 1010e52347bdSJani Nikula to be equivalent to 'mmio'. 'options' are specified 1011e52347bdSJani Nikula in the same format described for "console=ttyS<n>"; if 1012e52347bdSJani Nikula unspecified, the h/w is not initialized. 1013e52347bdSJani Nikula 1014e52347bdSJani Nikula pl011,<addr> 1015e52347bdSJani Nikula pl011,mmio32,<addr> 1016e52347bdSJani Nikula Start an early, polled-mode console on a pl011 serial 1017e52347bdSJani Nikula port at the specified address. The pl011 serial port 1018e52347bdSJani Nikula must already be setup and configured. Options are not 1019e52347bdSJani Nikula yet supported. If 'mmio32' is specified, then only 1020e52347bdSJani Nikula the driver will use only 32-bit accessors to read/write 1021e52347bdSJani Nikula the device registers. 1022e52347bdSJani Nikula 1023e52347bdSJani Nikula meson,<addr> 1024e52347bdSJani Nikula Start an early, polled-mode console on a meson serial 1025e52347bdSJani Nikula port at the specified address. The serial port must 1026e52347bdSJani Nikula already be setup and configured. Options are not yet 1027e52347bdSJani Nikula supported. 1028e52347bdSJani Nikula 1029e52347bdSJani Nikula msm_serial,<addr> 1030e52347bdSJani Nikula Start an early, polled-mode console on an msm serial 1031e52347bdSJani Nikula port at the specified address. The serial port 1032e52347bdSJani Nikula must already be setup and configured. Options are not 1033e52347bdSJani Nikula yet supported. 1034e52347bdSJani Nikula 1035e52347bdSJani Nikula msm_serial_dm,<addr> 1036e52347bdSJani Nikula Start an early, polled-mode console on an msm serial 1037e52347bdSJani Nikula dm port at the specified address. The serial port 1038e52347bdSJani Nikula must already be setup and configured. Options are not 1039e52347bdSJani Nikula yet supported. 1040e52347bdSJani Nikula 1041e36361d7SAndreas Färber owl,<addr> 1042e36361d7SAndreas Färber Start an early, polled-mode console on a serial port 1043e36361d7SAndreas Färber of an Actions Semi SoC, such as S500 or S900, at the 1044e36361d7SAndreas Färber specified address. The serial port must already be 1045e36361d7SAndreas Färber setup and configured. Options are not yet supported. 1046e36361d7SAndreas Färber 1047c10b1332SManivannan Sadhasivam rda,<addr> 1048c10b1332SManivannan Sadhasivam Start an early, polled-mode console on a serial port 1049c10b1332SManivannan Sadhasivam of an RDA Micro SoC, such as RDA8810PL, at the 1050c10b1332SManivannan Sadhasivam specified address. The serial port must already be 1051c10b1332SManivannan Sadhasivam setup and configured. Options are not yet supported. 1052c10b1332SManivannan Sadhasivam 105382f12ab3SPalmer Dabbelt sbi 105482f12ab3SPalmer Dabbelt Use RISC-V SBI (Supervisor Binary Interface) for early 105582f12ab3SPalmer Dabbelt console. 105682f12ab3SPalmer Dabbelt 1057e52347bdSJani Nikula smh Use ARM semihosting calls for early console. 1058e52347bdSJani Nikula 1059e52347bdSJani Nikula s3c2410,<addr> 1060e52347bdSJani Nikula s3c2412,<addr> 1061e52347bdSJani Nikula s3c2440,<addr> 1062e52347bdSJani Nikula s3c6400,<addr> 1063e52347bdSJani Nikula s5pv210,<addr> 1064e52347bdSJani Nikula exynos4210,<addr> 1065e52347bdSJani Nikula Use early console provided by serial driver available 1066e52347bdSJani Nikula on Samsung SoCs, requires selecting proper type and 1067e52347bdSJani Nikula a correct base address of the selected UART port. The 1068e52347bdSJani Nikula serial port must already be setup and configured. 1069e52347bdSJani Nikula Options are not yet supported. 1070e52347bdSJani Nikula 1071ec84aa0aSMartin Blumenstingl lantiq,<addr> 1072ec84aa0aSMartin Blumenstingl Start an early, polled-mode console on a lantiq serial 1073ec84aa0aSMartin Blumenstingl (lqasc) port at the specified address. The serial port 1074ec84aa0aSMartin Blumenstingl must already be setup and configured. Options are not 1075ec84aa0aSMartin Blumenstingl yet supported. 1076ec84aa0aSMartin Blumenstingl 1077e52347bdSJani Nikula lpuart,<addr> 1078e52347bdSJani Nikula lpuart32,<addr> 1079e52347bdSJani Nikula Use early console provided by Freescale LP UART driver 1080e52347bdSJani Nikula found on Freescale Vybrid and QorIQ LS1021A processors. 1081e52347bdSJani Nikula A valid base address must be provided, and the serial 1082e52347bdSJani Nikula port must already be setup and configured. 1083e52347bdSJani Nikula 1084f7c864e7SAndre Przywara ar3700_uart,<addr> 1085e52347bdSJani Nikula Start an early, polled-mode console on the 1086e52347bdSJani Nikula Armada 3700 serial port at the specified 1087e52347bdSJani Nikula address. The serial port must already be setup 1088e52347bdSJani Nikula and configured. Options are not yet supported. 1089e52347bdSJani Nikula 109043f1831bSKarthikeyan Ramasubramanian qcom_geni,<addr> 109143f1831bSKarthikeyan Ramasubramanian Start an early, polled-mode console on a Qualcomm 109243f1831bSKarthikeyan Ramasubramanian Generic Interface (GENI) based serial port at the 109343f1831bSKarthikeyan Ramasubramanian specified address. The serial port must already be 109443f1831bSKarthikeyan Ramasubramanian setup and configured. Options are not yet supported. 109543f1831bSKarthikeyan Ramasubramanian 109669c1f396SArd Biesheuvel efifb,[options] 109769c1f396SArd Biesheuvel Start an early, unaccelerated console on the EFI 109869c1f396SArd Biesheuvel memory mapped framebuffer (if available). On cache 109969c1f396SArd Biesheuvel coherent non-x86 systems that use system memory for 110069c1f396SArd Biesheuvel the framebuffer, pass the 'ram' option so that it is 110169c1f396SArd Biesheuvel mapped with the correct attributes. 110269c1f396SArd Biesheuvel 110309864c1cSStefan-gabriel Mirea linflex,<addr> 110409864c1cSStefan-gabriel Mirea Use early console provided by Freescale LinFlex UART 110509864c1cSStefan-gabriel Mirea serial driver for NXP S32V234 SoCs. A valid base 110609864c1cSStefan-gabriel Mirea address must be provided, and the serial port must 110709864c1cSStefan-gabriel Mirea already be setup and configured. 110809864c1cSStefan-gabriel Mirea 11094ba66a97SArnd Bergmann earlyprintk= [X86,SH,ARM,M68k,S390] 1110e52347bdSJani Nikula earlyprintk=vga 111189175cf7SHeiko Carstens earlyprintk=sclp 1112e52347bdSJani Nikula earlyprintk=xen 1113e52347bdSJani Nikula earlyprintk=serial[,ttySn[,baudrate]] 1114e52347bdSJani Nikula earlyprintk=serial[,0x...[,baudrate]] 1115e52347bdSJani Nikula earlyprintk=ttySn[,baudrate] 1116e52347bdSJani Nikula earlyprintk=dbgp[debugController#] 1117d2266bbfSFeng Tang earlyprintk=pciserial[,force],bus:device.function[,baudrate] 11181b5aeebfSLu Baolu earlyprintk=xdbc[xhciController#] 1119e52347bdSJani Nikula 1120e52347bdSJani Nikula earlyprintk is useful when the kernel crashes before 1121e52347bdSJani Nikula the normal console is initialized. It is not enabled by 1122e52347bdSJani Nikula default because it has some cosmetic problems. 1123e52347bdSJani Nikula 1124e52347bdSJani Nikula Append ",keep" to not disable it when the real console 1125e52347bdSJani Nikula takes over. 1126e52347bdSJani Nikula 1127e52347bdSJani Nikula Only one of vga, efi, serial, or usb debug port can 1128e52347bdSJani Nikula be used at a time. 1129e52347bdSJani Nikula 1130e52347bdSJani Nikula Currently only ttyS0 and ttyS1 may be specified by 1131e52347bdSJani Nikula name. Other I/O ports may be explicitly specified 1132e52347bdSJani Nikula on some architectures (x86 and arm at least) by 1133e52347bdSJani Nikula replacing ttySn with an I/O port address, like this: 1134e52347bdSJani Nikula earlyprintk=serial,0x1008,115200 1135e52347bdSJani Nikula You can find the port for a given device in 1136e52347bdSJani Nikula /proc/tty/driver/serial: 1137e52347bdSJani Nikula 2: uart:ST16650V2 port:00001008 irq:18 ... 1138e52347bdSJani Nikula 1139e52347bdSJani Nikula Interaction with the standard serial driver is not 1140e52347bdSJani Nikula very good. 1141e52347bdSJani Nikula 1142e52347bdSJani Nikula The VGA and EFI output is eventually overwritten by 1143e52347bdSJani Nikula the real console. 1144e52347bdSJani Nikula 1145e52347bdSJani Nikula The xen output can only be used by Xen PV guests. 1146e52347bdSJani Nikula 114789175cf7SHeiko Carstens The sclp output can only be used on s390. 114889175cf7SHeiko Carstens 1149d2266bbfSFeng Tang The optional "force" to "pciserial" enables use of a 1150d2266bbfSFeng Tang PCI device even when its classcode is not of the 1151d2266bbfSFeng Tang UART class. 1152d2266bbfSFeng Tang 1153e52347bdSJani Nikula edac_report= [HW,EDAC] Control how to report EDAC event 1154e52347bdSJani Nikula Format: {"on" | "off" | "force"} 1155e52347bdSJani Nikula on: enable EDAC to report H/W event. May be overridden 1156e52347bdSJani Nikula by other higher priority error reporting module. 1157e52347bdSJani Nikula off: disable H/W event reporting through EDAC. 1158e52347bdSJani Nikula force: enforce the use of EDAC to report H/W event. 1159e52347bdSJani Nikula default: on. 1160e52347bdSJani Nikula 1161e52347bdSJani Nikula ekgdboc= [X86,KGDB] Allow early kernel console debugging 1162e52347bdSJani Nikula ekgdboc=kbd 1163e52347bdSJani Nikula 1164e52347bdSJani Nikula This is designed to be used in conjunction with 1165e52347bdSJani Nikula the boot argument: earlyprintk=vga 1166e52347bdSJani Nikula 1167e52347bdSJani Nikula edd= [EDD] 1168e52347bdSJani Nikula Format: {"off" | "on" | "skip[mbr]"} 1169e52347bdSJani Nikula 1170e52347bdSJani Nikula efi= [EFI] 1171e52347bdSJani Nikula Format: { "old_map", "nochunk", "noruntime", "debug" } 1172e52347bdSJani Nikula old_map [X86-64]: switch to the old ioremap-based EFI 1173e52347bdSJani Nikula runtime services mapping. 32-bit still uses this one by 1174e52347bdSJani Nikula default. 1175e52347bdSJani Nikula nochunk: disable reading files in "chunks" in the EFI 1176e52347bdSJani Nikula boot stub, as chunking can cause problems with some 1177e52347bdSJani Nikula firmware implementations. 1178e52347bdSJani Nikula noruntime : disable EFI runtime services support 1179e52347bdSJani Nikula debug: enable misc debug output 1180e52347bdSJani Nikula 1181e52347bdSJani Nikula efi_no_storage_paranoia [EFI; X86] 1182e52347bdSJani Nikula Using this parameter you can use more than 50% of 1183e52347bdSJani Nikula your efi variable storage. Use this parameter only if 1184e52347bdSJani Nikula you are really sure that your UEFI does sane gc and 1185e52347bdSJani Nikula fulfills the spec otherwise your board may brick. 1186e52347bdSJani Nikula 1187e52347bdSJani Nikula efi_fake_mem= nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86] 1188e52347bdSJani Nikula Add arbitrary attribute to specific memory range by 1189e52347bdSJani Nikula updating original EFI memory map. 1190e52347bdSJani Nikula Region of memory which aa attribute is added to is 1191e52347bdSJani Nikula from ss to ss+nn. 1192e52347bdSJani Nikula If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000 1193e52347bdSJani Nikula is specified, EFI_MEMORY_MORE_RELIABLE(0x10000) 1194e52347bdSJani Nikula attribute is added to range 0x100000000-0x180000000 and 1195e52347bdSJani Nikula 0x10a0000000-0x1120000000. 1196e52347bdSJani Nikula 1197e52347bdSJani Nikula Using this parameter you can do debugging of EFI memmap 1198e52347bdSJani Nikula related feature. For example, you can do debugging of 1199e52347bdSJani Nikula Address Range Mirroring feature even if your box 1200e52347bdSJani Nikula doesn't support it. 1201e52347bdSJani Nikula 1202e52347bdSJani Nikula efivar_ssdt= [EFI; X86] Name of an EFI variable that contains an SSDT 1203e52347bdSJani Nikula that is to be dynamically loaded by Linux. If there are 1204e52347bdSJani Nikula multiple variables with the same name but with different 1205e52347bdSJani Nikula vendor GUIDs, all of them will be loaded. See 1206cb1aaebeSMauro Carvalho Chehab Documentation/admin-guide/acpi/ssdt-overlays.rst for details. 1207e52347bdSJani Nikula 1208e52347bdSJani Nikula 1209e52347bdSJani Nikula eisa_irq_edge= [PARISC,HW] 1210e52347bdSJani Nikula See header of drivers/parisc/eisa.c. 1211e52347bdSJani Nikula 1212e52347bdSJani Nikula elanfreq= [X86-32] 1213e52347bdSJani Nikula See comment before function elanfreq_setup() in 1214e52347bdSJani Nikula arch/x86/kernel/cpu/cpufreq/elanfreq.c. 1215e52347bdSJani Nikula 1216e52347bdSJani Nikula elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390] 1217e52347bdSJani Nikula Specifies physical address of start of kernel core 1218e52347bdSJani Nikula image elf header and optionally the size. Generally 1219e52347bdSJani Nikula kexec loader will pass this option to capture kernel. 1220330d4810SMauro Carvalho Chehab See Documentation/admin-guide/kdump/kdump.rst for details. 1221e52347bdSJani Nikula 1222e52347bdSJani Nikula enable_mtrr_cleanup [X86] 1223e52347bdSJani Nikula The kernel tries to adjust MTRR layout from continuous 1224e52347bdSJani Nikula to discrete, to make X server driver able to add WB 1225e52347bdSJani Nikula entry later. This parameter enables that. 1226e52347bdSJani Nikula 1227e52347bdSJani Nikula enable_timer_pin_1 [X86] 1228e52347bdSJani Nikula Enable PIN 1 of APIC timer 1229e52347bdSJani Nikula Can be useful to work around chipset bugs 1230e52347bdSJani Nikula (in particular on some ATI chipsets). 1231e52347bdSJani Nikula The kernel tries to set a reasonable default. 1232e52347bdSJani Nikula 1233e52347bdSJani Nikula enforcing [SELINUX] Set initial enforcing status. 1234e52347bdSJani Nikula Format: {"0" | "1"} 1235e52347bdSJani Nikula See security/selinux/Kconfig help text. 1236e52347bdSJani Nikula 0 -- permissive (log only, no denials). 1237e52347bdSJani Nikula 1 -- enforcing (deny and log). 1238e52347bdSJani Nikula Default value is 0. 1239e52347bdSJani Nikula Value can be changed at runtime via /selinux/enforce. 1240e52347bdSJani Nikula 1241e52347bdSJani Nikula erst_disable [ACPI] 1242e52347bdSJani Nikula Disable Error Record Serialization Table (ERST) 1243e52347bdSJani Nikula support. 1244e52347bdSJani Nikula 1245e52347bdSJani Nikula ether= [HW,NET] Ethernet cards parameters 1246e52347bdSJani Nikula This option is obsoleted by the "netdev=" option, which 1247e52347bdSJani Nikula has equivalent usage. See its documentation for details. 1248e52347bdSJani Nikula 1249e52347bdSJani Nikula evm= [EVM] 1250e52347bdSJani Nikula Format: { "fix" } 1251e52347bdSJani Nikula Permit 'security.evm' to be updated regardless of 1252e52347bdSJani Nikula current integrity status. 1253e52347bdSJani Nikula 1254e52347bdSJani Nikula failslab= 1255e52347bdSJani Nikula fail_page_alloc= 1256e52347bdSJani Nikula fail_make_request=[KNL] 1257e52347bdSJani Nikula General fault injection mechanism. 1258e52347bdSJani Nikula Format: <interval>,<probability>,<space>,<times> 1259e52347bdSJani Nikula See also Documentation/fault-injection/. 1260e52347bdSJani Nikula 1261e52347bdSJani Nikula floppy= [HW] 1262e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/floppy.rst. 1263e52347bdSJani Nikula 1264e52347bdSJani Nikula force_pal_cache_flush 1265e52347bdSJani Nikula [IA-64] Avoid check_sal_cache_flush which may hang on 1266e52347bdSJani Nikula buggy SAL_CACHE_FLUSH implementations. Using this 1267e52347bdSJani Nikula parameter will force ia64_sal_cache_flush to call 1268e52347bdSJani Nikula ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. 1269e52347bdSJani Nikula 1270e52347bdSJani Nikula forcepae [X86-32] 1271e52347bdSJani Nikula Forcefully enable Physical Address Extension (PAE). 1272e52347bdSJani Nikula Many Pentium M systems disable PAE but may have a 1273e52347bdSJani Nikula functionally usable PAE implementation. 1274e52347bdSJani Nikula Warning: use of this parameter will taint the kernel 1275e52347bdSJani Nikula and may cause unknown problems. 1276e52347bdSJani Nikula 1277e52347bdSJani Nikula ftrace=[tracer] 1278e52347bdSJani Nikula [FTRACE] will set and start the specified tracer 1279e52347bdSJani Nikula as early as possible in order to facilitate early 1280e52347bdSJani Nikula boot debugging. 1281e52347bdSJani Nikula 1282e52347bdSJani Nikula ftrace_dump_on_oops[=orig_cpu] 1283e52347bdSJani Nikula [FTRACE] will dump the trace buffers on oops. 1284e52347bdSJani Nikula If no parameter is passed, ftrace will dump 1285e52347bdSJani Nikula buffers of all CPUs, but if you pass orig_cpu, it will 1286e52347bdSJani Nikula dump only the buffer of the CPU that triggered the 1287e52347bdSJani Nikula oops. 1288e52347bdSJani Nikula 1289e52347bdSJani Nikula ftrace_filter=[function-list] 1290e52347bdSJani Nikula [FTRACE] Limit the functions traced by the function 1291e52347bdSJani Nikula tracer at boot up. function-list is a comma separated 1292e52347bdSJani Nikula list of functions. This list can be changed at run 1293e52347bdSJani Nikula time by the set_ftrace_filter file in the debugfs 1294e52347bdSJani Nikula tracing directory. 1295e52347bdSJani Nikula 1296e52347bdSJani Nikula ftrace_notrace=[function-list] 1297e52347bdSJani Nikula [FTRACE] Do not trace the functions specified in 1298e52347bdSJani Nikula function-list. This list can be changed at run time 1299e52347bdSJani Nikula by the set_ftrace_notrace file in the debugfs 1300e52347bdSJani Nikula tracing directory. 1301e52347bdSJani Nikula 1302e52347bdSJani Nikula ftrace_graph_filter=[function-list] 1303e52347bdSJani Nikula [FTRACE] Limit the top level callers functions traced 1304e52347bdSJani Nikula by the function graph tracer at boot up. 1305e52347bdSJani Nikula function-list is a comma separated list of functions 1306e52347bdSJani Nikula that can be changed at run time by the 1307e52347bdSJani Nikula set_graph_function file in the debugfs tracing directory. 1308e52347bdSJani Nikula 1309e52347bdSJani Nikula ftrace_graph_notrace=[function-list] 1310e52347bdSJani Nikula [FTRACE] Do not trace from the functions specified in 1311e52347bdSJani Nikula function-list. This list is a comma separated list of 1312e52347bdSJani Nikula functions that can be changed at run time by the 1313e52347bdSJani Nikula set_graph_notrace file in the debugfs tracing directory. 1314e52347bdSJani Nikula 131565a50c65STodd Brandt ftrace_graph_max_depth=<uint> 131665a50c65STodd Brandt [FTRACE] Used with the function graph tracer. This is 131765a50c65STodd Brandt the max depth it will trace into a function. This value 131865a50c65STodd Brandt can be changed at run time by the max_graph_depth file 131965a50c65STodd Brandt in the tracefs tracing directory. default: 0 (no limit) 132065a50c65STodd Brandt 1321e52347bdSJani Nikula gamecon.map[2|3]= 1322e52347bdSJani Nikula [HW,JOY] Multisystem joystick and NES/SNES/PSX pad 1323e52347bdSJani Nikula support via parallel port (up to 5 devices per port) 1324e52347bdSJani Nikula Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> 13251752118dSTom Saeger See also Documentation/input/devices/joystick-parport.rst 1326e52347bdSJani Nikula 1327e52347bdSJani Nikula gamma= [HW,DRM] 1328e52347bdSJani Nikula 1329e52347bdSJani Nikula gart_fix_e820= [X86_64] disable the fix e820 for K8 GART 1330e52347bdSJani Nikula Format: off | on 1331e52347bdSJani Nikula default: on 1332e52347bdSJani Nikula 1333e52347bdSJani Nikula gcov_persist= [GCOV] When non-zero (default), profiling data for 1334e52347bdSJani Nikula kernel modules is saved and remains accessible via 1335e52347bdSJani Nikula debugfs, even when the module is unloaded/reloaded. 1336e52347bdSJani Nikula When zero, profiling data is discarded and associated 1337e52347bdSJani Nikula debugfs files are removed at module unload time. 1338e52347bdSJani Nikula 133947512cfdSThomas Gleixner goldfish [X86] Enable the goldfish android emulator platform. 134047512cfdSThomas Gleixner Don't use this when you are not running on the 134147512cfdSThomas Gleixner android emulator 134247512cfdSThomas Gleixner 1343e52347bdSJani Nikula gpt [EFI] Forces disk with valid GPT signature but 1344e52347bdSJani Nikula invalid Protective MBR to be treated as GPT. If the 1345e52347bdSJani Nikula primary GPT is corrupted, it enables the backup/alternate 1346e52347bdSJani Nikula GPT to be used instead. 1347e52347bdSJani Nikula 1348e52347bdSJani Nikula grcan.enable0= [HW] Configuration of physical interface 0. Determines 1349e52347bdSJani Nikula the "Enable 0" bit of the configuration register. 1350e52347bdSJani Nikula Format: 0 | 1 1351e52347bdSJani Nikula Default: 0 1352e52347bdSJani Nikula grcan.enable1= [HW] Configuration of physical interface 1. Determines 1353e52347bdSJani Nikula the "Enable 0" bit of the configuration register. 1354e52347bdSJani Nikula Format: 0 | 1 1355e52347bdSJani Nikula Default: 0 1356e52347bdSJani Nikula grcan.select= [HW] Select which physical interface to use. 1357e52347bdSJani Nikula Format: 0 | 1 1358e52347bdSJani Nikula Default: 0 1359e52347bdSJani Nikula grcan.txsize= [HW] Sets the size of the tx buffer. 1360e52347bdSJani Nikula Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0. 1361e52347bdSJani Nikula Default: 1024 1362e52347bdSJani Nikula grcan.rxsize= [HW] Sets the size of the rx buffer. 1363e52347bdSJani Nikula Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. 1364e52347bdSJani Nikula Default: 1024 1365e52347bdSJani Nikula 1366e52347bdSJani Nikula gpio-mockup.gpio_mockup_ranges 1367e52347bdSJani Nikula [HW] Sets the ranges of gpiochip of for this device. 1368e52347bdSJani Nikula Format: <start1>,<end1>,<start2>,<end2>... 1369e52347bdSJani Nikula 1370e52347bdSJani Nikula hardlockup_all_cpu_backtrace= 1371e52347bdSJani Nikula [KNL] Should the hard-lockup detector generate 1372e52347bdSJani Nikula backtraces on all cpus. 1373e52347bdSJani Nikula Format: <integer> 1374e52347bdSJani Nikula 1375e52347bdSJani Nikula hashdist= [KNL,NUMA] Large hashes allocated during boot 1376e52347bdSJani Nikula are distributed across NUMA nodes. Defaults on 1377e52347bdSJani Nikula for 64-bit NUMA, off otherwise. 1378e52347bdSJani Nikula Format: 0 | 1 (for off | on) 1379e52347bdSJani Nikula 1380e52347bdSJani Nikula hcl= [IA-64] SGI's Hardware Graph compatibility layer 1381e52347bdSJani Nikula 1382e52347bdSJani Nikula hd= [EIDE] (E)IDE hard drive subsystem geometry 1383e52347bdSJani Nikula Format: <cyl>,<head>,<sect> 1384e52347bdSJani Nikula 1385e52347bdSJani Nikula hest_disable [ACPI] 1386e52347bdSJani Nikula Disable Hardware Error Source Table (HEST) support; 1387e52347bdSJani Nikula corresponding firmware-first mode error processing 1388e52347bdSJani Nikula logic will be disabled. 1389e52347bdSJani Nikula 1390e52347bdSJani Nikula highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact 1391e52347bdSJani Nikula size of <nn>. This works even on boxes that have no 1392e52347bdSJani Nikula highmem otherwise. This also works to reduce highmem 1393e52347bdSJani Nikula size on bigger boxes. 1394e52347bdSJani Nikula 1395e52347bdSJani Nikula highres= [KNL] Enable/disable high resolution timer mode. 1396e52347bdSJani Nikula Valid parameters: "on", "off" 1397e52347bdSJani Nikula Default: "on" 1398e52347bdSJani Nikula 1399e52347bdSJani Nikula hlt [BUGS=ARM,SH] 1400e52347bdSJani Nikula 1401e52347bdSJani Nikula hpet= [X86-32,HPET] option to control HPET usage 1402e52347bdSJani Nikula Format: { enable (default) | disable | force | 1403e52347bdSJani Nikula verbose } 1404e52347bdSJani Nikula disable: disable HPET and use PIT instead 1405e52347bdSJani Nikula force: allow force enabled of undocumented chips (ICH4, 1406e52347bdSJani Nikula VIA, nVidia) 1407e52347bdSJani Nikula verbose: show contents of HPET registers during setup 1408e52347bdSJani Nikula 1409e52347bdSJani Nikula hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET 1410e52347bdSJani Nikula registers. Default set by CONFIG_HPET_MMAP_DEFAULT. 1411e52347bdSJani Nikula 1412e52347bdSJani Nikula hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. 1413e52347bdSJani Nikula hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. 1414e52347bdSJani Nikula On x86-64 and powerpc, this option can be specified 1415e52347bdSJani Nikula multiple times interleaved with hugepages= to reserve 1416e52347bdSJani Nikula huge pages of different sizes. Valid pages sizes on 1417e52347bdSJani Nikula x86-64 are 2M (when the CPU supports "pse") and 1G 1418e52347bdSJani Nikula (when the CPU supports the "pdpe1gb" cpuinfo flag). 1419e52347bdSJani Nikula 1420a49d9c0aSOmar Sandoval hung_task_panic= 1421a49d9c0aSOmar Sandoval [KNL] Should the hung task detector generate panics. 1422a49d9c0aSOmar Sandoval Format: <integer> 1423a49d9c0aSOmar Sandoval 1424a49d9c0aSOmar Sandoval A nonzero value instructs the kernel to panic when a 1425a49d9c0aSOmar Sandoval hung task is detected. The default value is controlled 1426a49d9c0aSOmar Sandoval by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time 1427a49d9c0aSOmar Sandoval option. The value selected by this boot parameter can 1428a49d9c0aSOmar Sandoval be changed later by the kernel.hung_task_panic sysctl. 1429a49d9c0aSOmar Sandoval 1430e52347bdSJani Nikula hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) 1431e52347bdSJani Nikula terminal devices. Valid values: 0..8 1432e52347bdSJani Nikula hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. 1433e52347bdSJani Nikula If specified, z/VM IUCV HVC accepts connections 1434e52347bdSJani Nikula from listed z/VM user IDs only. 14353a025de6SYi Sun 14363a025de6SYi Sun hv_nopvspin [X86,HYPER_V] Disables the paravirt spinlock optimizations 14373a025de6SYi Sun which allow the hypervisor to 'idle' the 14383a025de6SYi Sun guest on lock contention. 14393a025de6SYi Sun 1440e52347bdSJani Nikula keep_bootcon [KNL] 1441e52347bdSJani Nikula Do not unregister boot console at start. This is only 1442e52347bdSJani Nikula useful for debugging when something happens in the window 1443e52347bdSJani Nikula between unregistering the boot console and initializing 1444e52347bdSJani Nikula the real console. 1445e52347bdSJani Nikula 1446e52347bdSJani Nikula i2c_bus= [HW] Override the default board specific I2C bus speed 1447e52347bdSJani Nikula or register an additional I2C bus that is not 1448e52347bdSJani Nikula registered from board initialization code. 1449e52347bdSJani Nikula Format: 1450e52347bdSJani Nikula <bus_id>,<clkrate> 1451e52347bdSJani Nikula 1452e52347bdSJani Nikula i8042.debug [HW] Toggle i8042 debug mode 1453e52347bdSJani Nikula i8042.unmask_kbd_data 1454e52347bdSJani Nikula [HW] Enable printing of interrupt data from the KBD port 1455e52347bdSJani Nikula (disabled by default, and as a pre-condition 1456e52347bdSJani Nikula requires that i8042.debug=1 be enabled) 1457e52347bdSJani Nikula i8042.direct [HW] Put keyboard port into non-translated mode 1458e52347bdSJani Nikula i8042.dumbkbd [HW] Pretend that controller can only read data from 1459e52347bdSJani Nikula keyboard and cannot control its state 1460e52347bdSJani Nikula (Don't attempt to blink the leds) 1461e52347bdSJani Nikula i8042.noaux [HW] Don't check for auxiliary (== mouse) port 1462e52347bdSJani Nikula i8042.nokbd [HW] Don't check/create keyboard port 1463e52347bdSJani Nikula i8042.noloop [HW] Disable the AUX Loopback command while probing 1464e52347bdSJani Nikula for the AUX port 1465e52347bdSJani Nikula i8042.nomux [HW] Don't check presence of an active multiplexing 1466e52347bdSJani Nikula controller 1467e52347bdSJani Nikula i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX 1468e52347bdSJani Nikula controllers 1469e52347bdSJani Nikula i8042.notimeout [HW] Ignore timeout condition signalled by controller 1470e52347bdSJani Nikula i8042.reset [HW] Reset the controller during init, cleanup and 1471e52347bdSJani Nikula suspend-to-ram transitions, only during s2r 1472e52347bdSJani Nikula transitions, or never reset 1473e52347bdSJani Nikula Format: { 1 | Y | y | 0 | N | n } 1474e52347bdSJani Nikula 1, Y, y: always reset controller 1475e52347bdSJani Nikula 0, N, n: don't ever reset controller 1476e52347bdSJani Nikula Default: only on s2r transitions on x86; most other 1477e52347bdSJani Nikula architectures force reset to be always executed 1478e52347bdSJani Nikula i8042.unlock [HW] Unlock (ignore) the keylock 1479e52347bdSJani Nikula i8042.kbdreset [HW] Reset device connected to KBD port 1480e52347bdSJani Nikula 1481e52347bdSJani Nikula i810= [HW,DRM] 1482e52347bdSJani Nikula 1483e52347bdSJani Nikula i8k.ignore_dmi [HW] Continue probing hardware even if DMI data 1484e52347bdSJani Nikula indicates that the driver is running on unsupported 1485e52347bdSJani Nikula hardware. 1486e52347bdSJani Nikula i8k.force [HW] Activate i8k driver even if SMM BIOS signature 1487e52347bdSJani Nikula does not match list of supported models. 1488e52347bdSJani Nikula i8k.power_status 1489e52347bdSJani Nikula [HW] Report power status in /proc/i8k 1490e52347bdSJani Nikula (disabled by default) 1491e52347bdSJani Nikula i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN 1492e52347bdSJani Nikula capability is set. 1493e52347bdSJani Nikula 1494e52347bdSJani Nikula i915.invert_brightness= 1495e52347bdSJani Nikula [DRM] Invert the sense of the variable that is used to 1496e52347bdSJani Nikula set the brightness of the panel backlight. Normally a 1497e52347bdSJani Nikula brightness value of 0 indicates backlight switched off, 1498e52347bdSJani Nikula and the maximum of the brightness value sets the backlight 1499e52347bdSJani Nikula to maximum brightness. If this parameter is set to 0 1500e52347bdSJani Nikula (default) and the machine requires it, or this parameter 1501e52347bdSJani Nikula is set to 1, a brightness value of 0 sets the backlight 1502e52347bdSJani Nikula to maximum brightness, and the maximum of the brightness 1503e52347bdSJani Nikula value switches the backlight off. 1504e52347bdSJani Nikula -1 -- never invert brightness 1505e52347bdSJani Nikula 0 -- machine default 1506e52347bdSJani Nikula 1 -- force brightness inversion 1507e52347bdSJani Nikula 1508e52347bdSJani Nikula icn= [HW,ISDN] 1509e52347bdSJani Nikula Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] 1510e52347bdSJani Nikula 1511e52347bdSJani Nikula ide-core.nodma= [HW] (E)IDE subsystem 1512e52347bdSJani Nikula Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc 1513e52347bdSJani Nikula .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr 1514e52347bdSJani Nikula .cdrom .chs .ignore_cable are additional options 1515d7b461c5SMauro Carvalho Chehab See Documentation/ide/ide.rst. 1516e52347bdSJani Nikula 1517e52347bdSJani Nikula ide-generic.probe-mask= [HW] (E)IDE subsystem 1518e52347bdSJani Nikula Format: <int> 1519e52347bdSJani Nikula Probe mask for legacy ISA IDE ports. Depending on 1520e52347bdSJani Nikula platform up to 6 ports are supported, enabled by 1521e52347bdSJani Nikula setting corresponding bits in the mask to 1. The 1522e52347bdSJani Nikula default value is 0x0, which has a special meaning. 1523e52347bdSJani Nikula On systems that have PCI, it triggers scanning the 1524e52347bdSJani Nikula PCI bus for the first and the second port, which 1525e52347bdSJani Nikula are then probed. On systems without PCI the value 1526e52347bdSJani Nikula of 0x0 enables probing the two first ports as if it 1527e52347bdSJani Nikula was 0x3. 1528e52347bdSJani Nikula 1529e52347bdSJani Nikula ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem 1530e52347bdSJani Nikula Claim all unknown PCI IDE storage controllers. 1531e52347bdSJani Nikula 1532e52347bdSJani Nikula idle= [X86] 1533e52347bdSJani Nikula Format: idle=poll, idle=halt, idle=nomwait 1534e52347bdSJani Nikula Poll forces a polling idle loop that can slightly 1535e52347bdSJani Nikula improve the performance of waking up a idle CPU, but 1536e52347bdSJani Nikula will use a lot of power and make the system run hot. 1537e52347bdSJani Nikula Not recommended. 1538e52347bdSJani Nikula idle=halt: Halt is forced to be used for CPU idle. 1539e52347bdSJani Nikula In such case C2/C3 won't be used again. 1540e52347bdSJani Nikula idle=nomwait: Disable mwait for CPU C-states 1541e52347bdSJani Nikula 1542e52347bdSJani Nikula ieee754= [MIPS] Select IEEE Std 754 conformance mode 1543e52347bdSJani Nikula Format: { strict | legacy | 2008 | relaxed } 1544e52347bdSJani Nikula Default: strict 1545e52347bdSJani Nikula 1546e52347bdSJani Nikula Choose which programs will be accepted for execution 1547e52347bdSJani Nikula based on the IEEE 754 NaN encoding(s) supported by 1548e52347bdSJani Nikula the FPU and the NaN encoding requested with the value 1549e52347bdSJani Nikula of an ELF file header flag individually set by each 1550e52347bdSJani Nikula binary. Hardware implementations are permitted to 1551e52347bdSJani Nikula support either or both of the legacy and the 2008 NaN 1552e52347bdSJani Nikula encoding mode. 1553e52347bdSJani Nikula 1554e52347bdSJani Nikula Available settings are as follows: 1555e52347bdSJani Nikula strict accept binaries that request a NaN encoding 1556e52347bdSJani Nikula supported by the FPU 1557e52347bdSJani Nikula legacy only accept legacy-NaN binaries, if supported 1558e52347bdSJani Nikula by the FPU 1559e52347bdSJani Nikula 2008 only accept 2008-NaN binaries, if supported 1560e52347bdSJani Nikula by the FPU 1561e52347bdSJani Nikula relaxed accept any binaries regardless of whether 1562e52347bdSJani Nikula supported by the FPU 1563e52347bdSJani Nikula 1564e52347bdSJani Nikula The FPU emulator is always able to support both NaN 1565e52347bdSJani Nikula encodings, so if no FPU hardware is present or it has 1566e52347bdSJani Nikula been disabled with 'nofpu', then the settings of 1567e52347bdSJani Nikula 'legacy' and '2008' strap the emulator accordingly, 1568e52347bdSJani Nikula 'relaxed' straps the emulator for both legacy-NaN and 1569e52347bdSJani Nikula 2008-NaN, whereas 'strict' enables legacy-NaN only on 1570e52347bdSJani Nikula legacy processors and both NaN encodings on MIPS32 or 1571e52347bdSJani Nikula MIPS64 CPUs. 1572e52347bdSJani Nikula 1573e52347bdSJani Nikula The setting for ABS.fmt/NEG.fmt instruction execution 1574e52347bdSJani Nikula mode generally follows that for the NaN encoding, 1575e52347bdSJani Nikula except where unsupported by hardware. 1576e52347bdSJani Nikula 1577e52347bdSJani Nikula ignore_loglevel [KNL] 1578e52347bdSJani Nikula Ignore loglevel setting - this will print /all/ 1579e52347bdSJani Nikula kernel messages to the console. Useful for debugging. 1580e52347bdSJani Nikula We also add it as printk module parameter, so users 1581e52347bdSJani Nikula could change it dynamically, usually by 1582e52347bdSJani Nikula /sys/module/printk/parameters/ignore_loglevel. 1583e52347bdSJani Nikula 1584e52347bdSJani Nikula ignore_rlimit_data 1585e52347bdSJani Nikula Ignore RLIMIT_DATA setting for data mappings, 1586e52347bdSJani Nikula print warning at first misuse. Can be changed via 1587e52347bdSJani Nikula /sys/module/kernel/parameters/ignore_rlimit_data. 1588e52347bdSJani Nikula 1589e52347bdSJani Nikula ihash_entries= [KNL] 1590e52347bdSJani Nikula Set number of hash buckets for inode cache. 1591e52347bdSJani Nikula 1592e52347bdSJani Nikula ima_appraise= [IMA] appraise integrity measurements 1593e52347bdSJani Nikula Format: { "off" | "enforce" | "fix" | "log" } 1594e52347bdSJani Nikula default: "enforce" 1595e52347bdSJani Nikula 159641475a3eSPetr Vorel ima_appraise_tcb [IMA] Deprecated. Use ima_policy= instead. 1597e52347bdSJani Nikula The builtin appraise policy appraises all files 1598e52347bdSJani Nikula owned by uid=0. 1599e52347bdSJani Nikula 1600d68a6fe9SMimi Zohar ima_canonical_fmt [IMA] 1601d68a6fe9SMimi Zohar Use the canonical format for the binary runtime 1602d68a6fe9SMimi Zohar measurements, instead of host native format. 1603d68a6fe9SMimi Zohar 1604e52347bdSJani Nikula ima_hash= [IMA] 1605e52347bdSJani Nikula Format: { md5 | sha1 | rmd160 | sha256 | sha384 1606e52347bdSJani Nikula | sha512 | ... } 1607e52347bdSJani Nikula default: "sha1" 1608e52347bdSJani Nikula 1609e52347bdSJani Nikula The list of supported hash algorithms is defined 1610e52347bdSJani Nikula in crypto/hash_info.h. 1611e52347bdSJani Nikula 1612e52347bdSJani Nikula ima_policy= [IMA] 161333ce9549SMimi Zohar The builtin policies to load during IMA setup. 16149e67028eSMimi Zohar Format: "tcb | appraise_tcb | secure_boot | 16159e67028eSMimi Zohar fail_securely" 161633ce9549SMimi Zohar 161733ce9549SMimi Zohar The "tcb" policy measures all programs exec'd, files 161833ce9549SMimi Zohar mmap'd for exec, and all files opened with the read 161933ce9549SMimi Zohar mode bit set by either the effective uid (euid=0) or 162033ce9549SMimi Zohar uid=0. 162133ce9549SMimi Zohar 162233ce9549SMimi Zohar The "appraise_tcb" policy appraises the integrity of 162341475a3eSPetr Vorel all files owned by root. 1624e52347bdSJani Nikula 1625503ceaefSMimi Zohar The "secure_boot" policy appraises the integrity 1626503ceaefSMimi Zohar of files (eg. kexec kernel image, kernel modules, 1627503ceaefSMimi Zohar firmware, policy, etc) based on file signatures. 1628e52347bdSJani Nikula 16299e67028eSMimi Zohar The "fail_securely" policy forces file signature 16309e67028eSMimi Zohar verification failure also on privileged mounted 16319e67028eSMimi Zohar filesystems with the SB_I_UNVERIFIABLE_SIGNATURE 16329e67028eSMimi Zohar flag. 16339e67028eSMimi Zohar 1634e52347bdSJani Nikula ima_tcb [IMA] Deprecated. Use ima_policy= instead. 1635e52347bdSJani Nikula Load a policy which meets the needs of the Trusted 1636e52347bdSJani Nikula Computing Base. This means IMA will measure all 1637e52347bdSJani Nikula programs exec'd, files mmap'd for exec, and all files 1638e52347bdSJani Nikula opened for read by uid=0. 1639e52347bdSJani Nikula 1640e52347bdSJani Nikula ima_template= [IMA] 1641e52347bdSJani Nikula Select one of defined IMA measurements template formats. 1642e52347bdSJani Nikula Formats: { "ima" | "ima-ng" | "ima-sig" } 1643e52347bdSJani Nikula Default: "ima-ng" 1644e52347bdSJani Nikula 1645e52347bdSJani Nikula ima_template_fmt= 1646e52347bdSJani Nikula [IMA] Define a custom template format. 1647e52347bdSJani Nikula Format: { "field1|...|fieldN" } 1648e52347bdSJani Nikula 1649e52347bdSJani Nikula ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage 1650e52347bdSJani Nikula Format: <min_file_size> 1651e52347bdSJani Nikula Set the minimal file size for using asynchronous hash. 1652e52347bdSJani Nikula If left unspecified, ahash usage is disabled. 1653e52347bdSJani Nikula 1654e52347bdSJani Nikula ahash performance varies for different data sizes on 1655e52347bdSJani Nikula different crypto accelerators. This option can be used 1656e52347bdSJani Nikula to achieve the best performance for a particular HW. 1657e52347bdSJani Nikula 1658e52347bdSJani Nikula ima.ahash_bufsize= [IMA] Asynchronous hash buffer size 1659e52347bdSJani Nikula Format: <bufsize> 1660e52347bdSJani Nikula Set hashing buffer size. Default: 4k. 1661e52347bdSJani Nikula 1662e52347bdSJani Nikula ahash performance varies for different chunk sizes on 1663e52347bdSJani Nikula different crypto accelerators. This option can be used 1664e52347bdSJani Nikula to achieve best performance for particular HW. 1665e52347bdSJani Nikula 1666e52347bdSJani Nikula init= [KNL] 1667e52347bdSJani Nikula Format: <full_path> 1668e52347bdSJani Nikula Run specified binary instead of /sbin/init as init 1669e52347bdSJani Nikula process. 1670e52347bdSJani Nikula 1671e52347bdSJani Nikula initcall_debug [KNL] Trace initcalls as they are executed. Useful 1672e52347bdSJani Nikula for working out where the kernel is dying during 1673e52347bdSJani Nikula startup. 1674e52347bdSJani Nikula 1675e52347bdSJani Nikula initcall_blacklist= [KNL] Do not execute a comma-separated list of 1676e52347bdSJani Nikula initcall functions. Useful for debugging built-in 1677e52347bdSJani Nikula modules and initcalls. 1678e52347bdSJani Nikula 1679e52347bdSJani Nikula initrd= [BOOT] Specify the location of the initial ramdisk 1680e52347bdSJani Nikula 16816471384aSAlexander Potapenko init_on_alloc= [MM] Fill newly allocated pages and heap objects with 16826471384aSAlexander Potapenko zeroes. 16836471384aSAlexander Potapenko Format: 0 | 1 16846471384aSAlexander Potapenko Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON. 16856471384aSAlexander Potapenko 16866471384aSAlexander Potapenko init_on_free= [MM] Fill freed pages and heap objects with zeroes. 16876471384aSAlexander Potapenko Format: 0 | 1 16886471384aSAlexander Potapenko Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON. 16896471384aSAlexander Potapenko 1690e52347bdSJani Nikula init_pkru= [x86] Specify the default memory protection keys rights 1691e52347bdSJani Nikula register contents for all processes. 0x55555554 by 1692e52347bdSJani Nikula default (disallow access to all but pkey 0). Can 1693e52347bdSJani Nikula override in debugfs after boot. 1694e52347bdSJani Nikula 1695e52347bdSJani Nikula inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver 1696e52347bdSJani Nikula Format: <irq> 1697e52347bdSJani Nikula 1698e52347bdSJani Nikula int_pln_enable [x86] Enable power limit notification interrupt 1699e52347bdSJani Nikula 1700e52347bdSJani Nikula integrity_audit=[IMA] 1701e52347bdSJani Nikula Format: { "0" | "1" } 1702e52347bdSJani Nikula 0 -- basic integrity auditing messages. (Default) 1703e52347bdSJani Nikula 1 -- additional integrity auditing messages. 1704e52347bdSJani Nikula 1705e52347bdSJani Nikula intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option 1706e52347bdSJani Nikula on 1707e52347bdSJani Nikula Enable intel iommu driver. 1708e52347bdSJani Nikula off 1709e52347bdSJani Nikula Disable intel iommu driver. 1710e52347bdSJani Nikula igfx_off [Default Off] 1711e52347bdSJani Nikula By default, gfx is mapped as normal device. If a gfx 1712e52347bdSJani Nikula device has a dedicated DMAR unit, the DMAR unit is 1713e52347bdSJani Nikula bypassed by not enabling DMAR with this option. In 1714e52347bdSJani Nikula this case, gfx device will use physical address for 1715e52347bdSJani Nikula DMA. 1716e52347bdSJani Nikula forcedac [x86_64] 1717e52347bdSJani Nikula With this option iommu will not optimize to look 1718e52347bdSJani Nikula for io virtual address below 32-bit forcing dual 1719e52347bdSJani Nikula address cycle on pci bus for cards supporting greater 1720e52347bdSJani Nikula than 32-bit addressing. The default is to look 1721e52347bdSJani Nikula for translation below 32-bit and if not available 1722e52347bdSJani Nikula then look in the higher range. 1723e52347bdSJani Nikula strict [Default Off] 1724e52347bdSJani Nikula With this option on every unmap_single operation will 1725e52347bdSJani Nikula result in a hardware IOTLB flush operation as opposed 1726e52347bdSJani Nikula to batching them for performance. 1727e52347bdSJani Nikula sp_off [Default Off] 1728e52347bdSJani Nikula By default, super page will be supported if Intel IOMMU 1729e52347bdSJani Nikula has the capability. With this option, super page will 1730e52347bdSJani Nikula not be supported. 17318950dcd8SLu Baolu sm_on [Default Off] 17328950dcd8SLu Baolu By default, scalable mode will be disabled even if the 1733765b6a98SLu Baolu hardware advertises that it has support for the scalable 1734765b6a98SLu Baolu mode translation. With this option set, scalable mode 17358950dcd8SLu Baolu will be used on hardware which claims to support it. 1736bfd20f1cSShaohua Li tboot_noforce [Default Off] 1737bfd20f1cSShaohua Li Do not force the Intel IOMMU enabled under tboot. 1738bfd20f1cSShaohua Li By default, tboot will force Intel IOMMU on, which 1739bfd20f1cSShaohua Li could harm performance of some high-throughput 1740bfd20f1cSShaohua Li devices like 40GBit network cards, even if identity 1741bfd20f1cSShaohua Li mapping is enabled. 1742bfd20f1cSShaohua Li Note that using this option lowers the security 1743bfd20f1cSShaohua Li provided by tboot because it makes the system 1744bfd20f1cSShaohua Li vulnerable to DMA attacks. 1745e5e04d05SLu Baolu nobounce [Default off] 1746e5e04d05SLu Baolu Disable bounce buffer for unstrusted devices such as 1747e5e04d05SLu Baolu the Thunderbolt devices. This will treat the untrusted 1748e5e04d05SLu Baolu devices as the trusted ones, hence might expose security 1749e5e04d05SLu Baolu risks of DMA attacks. 1750e52347bdSJani Nikula 1751e52347bdSJani Nikula intel_idle.max_cstate= [KNL,HW,ACPI,X86] 1752e52347bdSJani Nikula 0 disables intel_idle and fall back on acpi_idle. 1753e52347bdSJani Nikula 1 to 9 specify maximum depth of C-state. 1754e52347bdSJani Nikula 1755e52347bdSJani Nikula intel_pstate= [X86] 1756e52347bdSJani Nikula disable 1757e52347bdSJani Nikula Do not enable intel_pstate as the default 1758e52347bdSJani Nikula scaling driver for the supported processors 17597b9dc3f7SLinus Torvalds passive 17607b9dc3f7SLinus Torvalds Use intel_pstate as a scaling driver, but configure it 17617b9dc3f7SLinus Torvalds to work with generic cpufreq governors (instead of 17627b9dc3f7SLinus Torvalds enabling its internal governor). This mode cannot be 17637b9dc3f7SLinus Torvalds used along with the hardware-managed P-states (HWP) 17647b9dc3f7SLinus Torvalds feature. 1765e52347bdSJani Nikula force 1766e52347bdSJani Nikula Enable intel_pstate on systems that prohibit it by default 1767e52347bdSJani Nikula in favor of acpi-cpufreq. Forcing the intel_pstate driver 1768e52347bdSJani Nikula instead of acpi-cpufreq may disable platform features, such 1769e52347bdSJani Nikula as thermal controls and power capping, that rely on ACPI 1770e52347bdSJani Nikula P-States information being indicated to OSPM and therefore 1771e52347bdSJani Nikula should be used with caution. This option does not work with 1772e52347bdSJani Nikula processors that aren't supported by the intel_pstate driver 1773e52347bdSJani Nikula or on platforms that use pcc-cpufreq instead of acpi-cpufreq. 1774e52347bdSJani Nikula no_hwp 1775e52347bdSJani Nikula Do not enable hardware P state control (HWP) 1776e52347bdSJani Nikula if available. 1777e52347bdSJani Nikula hwp_only 1778e52347bdSJani Nikula Only load intel_pstate on systems which support 1779e52347bdSJani Nikula hardware P state control (HWP) if available. 1780e52347bdSJani Nikula support_acpi_ppc 1781e52347bdSJani Nikula Enforce ACPI _PPC performance limits. If the Fixed ACPI 1782e52347bdSJani Nikula Description Table, specifies preferred power management 1783e52347bdSJani Nikula profile as "Enterprise Server" or "Performance Server", 1784e52347bdSJani Nikula then this feature is turned on by default. 17857b9dc3f7SLinus Torvalds per_cpu_perf_limits 17867b9dc3f7SLinus Torvalds Allow per-logical-CPU P-State performance control limits using 17877b9dc3f7SLinus Torvalds cpufreq sysfs interface 1788e52347bdSJani Nikula 1789e52347bdSJani Nikula intremap= [X86-64, Intel-IOMMU] 1790e52347bdSJani Nikula on enable Interrupt Remapping (default) 1791e52347bdSJani Nikula off disable Interrupt Remapping 1792e52347bdSJani Nikula nosid disable Source ID checking 1793e52347bdSJani Nikula no_x2apic_optout 1794e52347bdSJani Nikula BIOS x2APIC opt-out request will be ignored 1795e52347bdSJani Nikula nopost disable Interrupt Posting 1796e52347bdSJani Nikula 1797e52347bdSJani Nikula iomem= Disable strict checking of access to MMIO memory 1798e52347bdSJani Nikula strict regions from userspace. 1799e52347bdSJani Nikula relaxed 1800e52347bdSJani Nikula 1801e52347bdSJani Nikula iommu= [x86] 1802e52347bdSJani Nikula off 1803e52347bdSJani Nikula force 1804e52347bdSJani Nikula noforce 1805e52347bdSJani Nikula biomerge 1806e52347bdSJani Nikula panic 1807e52347bdSJani Nikula nopanic 1808e52347bdSJani Nikula merge 1809e52347bdSJani Nikula nomerge 1810e52347bdSJani Nikula soft 181158d11317SOlof Johansson pt [x86] 181258d11317SOlof Johansson nopt [x86] 1813e52347bdSJani Nikula nobypass [PPC/POWERNV] 1814e52347bdSJani Nikula Disable IOMMU bypass, using IOMMU for PCI devices. 1815e52347bdSJani Nikula 181668a6efe8SZhen Lei iommu.strict= [ARM64] Configure TLB invalidation behaviour 181768a6efe8SZhen Lei Format: { "0" | "1" } 181868a6efe8SZhen Lei 0 - Lazy mode. 181968a6efe8SZhen Lei Request that DMA unmap operations use deferred 182068a6efe8SZhen Lei invalidation of hardware TLBs, for increased 182168a6efe8SZhen Lei throughput at the cost of reduced device isolation. 182268a6efe8SZhen Lei Will fall back to strict mode if not supported by 182368a6efe8SZhen Lei the relevant IOMMU driver. 182468a6efe8SZhen Lei 1 - Strict mode (default). 182568a6efe8SZhen Lei DMA unmap operations invalidate IOMMU hardware TLBs 182668a6efe8SZhen Lei synchronously. 182768a6efe8SZhen Lei 1828fccb4e3bSWill Deacon iommu.passthrough= 1829c8fb436bSJoerg Roedel [ARM64, X86] Configure DMA to bypass the IOMMU by default. 1830fccb4e3bSWill Deacon Format: { "0" | "1" } 1831fccb4e3bSWill Deacon 0 - Use IOMMU translation for DMA. 1832fccb4e3bSWill Deacon 1 - Bypass the IOMMU for DMA. 18339d723b4cSRobin Murphy unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH. 1834e52347bdSJani Nikula 1835e52347bdSJani Nikula io7= [HW] IO7 for Marvel based alpha systems 1836e52347bdSJani Nikula See comment before marvel_specify_io7 in 1837e52347bdSJani Nikula arch/alpha/kernel/core_marvel.c. 1838e52347bdSJani Nikula 1839e52347bdSJani Nikula io_delay= [X86] I/O delay method 1840e52347bdSJani Nikula 0x80 1841e52347bdSJani Nikula Standard port 0x80 based delay 1842e52347bdSJani Nikula 0xed 1843e52347bdSJani Nikula Alternate port 0xed based delay (needed on some systems) 1844e52347bdSJani Nikula udelay 1845e52347bdSJani Nikula Simple two microseconds delay 1846e52347bdSJani Nikula none 1847e52347bdSJani Nikula No delay 1848e52347bdSJani Nikula 1849e52347bdSJani Nikula ip= [IP_PNP] 1850e52347bdSJani Nikula See Documentation/filesystems/nfs/nfsroot.txt. 1851e52347bdSJani Nikula 18525ac893b8SWaiman Long ipcmni_extend [KNL] Extend the maximum number of unique System V 18535ac893b8SWaiman Long IPC identifiers from 32,768 to 16,777,216. 18545ac893b8SWaiman Long 1855e52347bdSJani Nikula irqaffinity= [SMP] Set the default irq affinity mask 1856e52347bdSJani Nikula The argument is a cpu list, as described above. 1857e52347bdSJani Nikula 18580962289bSMarc Zyngier irqchip.gicv2_force_probe= 18590962289bSMarc Zyngier [ARM, ARM64] 18600962289bSMarc Zyngier Format: <bool> 18610962289bSMarc Zyngier Force the kernel to look for the second 4kB page 18620962289bSMarc Zyngier of a GICv2 controller even if the memory range 18630962289bSMarc Zyngier exposed by the device tree is too small. 18640962289bSMarc Zyngier 1865f736d65dSMarc Zyngier irqchip.gicv3_nolpi= 1866f736d65dSMarc Zyngier [ARM, ARM64] 1867f736d65dSMarc Zyngier Force the kernel to ignore the availability of 1868f736d65dSMarc Zyngier LPIs (and by consequence ITSs). Intended for system 1869f736d65dSMarc Zyngier that use the kernel as a bootloader, and thus want 1870f736d65dSMarc Zyngier to let secondary kernels in charge of setting up 1871f736d65dSMarc Zyngier LPIs. 1872f736d65dSMarc Zyngier 1873bc3c03ccSJulien Thierry irqchip.gicv3_pseudo_nmi= [ARM64] 1874bc3c03ccSJulien Thierry Enables support for pseudo-NMIs in the kernel. This 1875bc3c03ccSJulien Thierry requires the kernel to be built with 1876bc3c03ccSJulien Thierry CONFIG_ARM64_PSEUDO_NMI. 1877bc3c03ccSJulien Thierry 1878e52347bdSJani Nikula irqfixup [HW] 1879e52347bdSJani Nikula When an interrupt is not handled search all handlers 1880e52347bdSJani Nikula for it. Intended to get systems with badly broken 1881e52347bdSJani Nikula firmware running. 1882e52347bdSJani Nikula 1883e52347bdSJani Nikula irqpoll [HW] 1884e52347bdSJani Nikula When an interrupt is not handled search all handlers 1885e52347bdSJani Nikula for it. Also check all handlers each timer 1886e52347bdSJani Nikula interrupt. Intended to get systems with badly broken 1887e52347bdSJani Nikula firmware running. 1888e52347bdSJani Nikula 1889e52347bdSJani Nikula isapnp= [ISAPNP] 1890e52347bdSJani Nikula Format: <RDP>,<reset>,<pci_scan>,<verbosity> 1891e52347bdSJani Nikula 1892d94d1053SFrederic Weisbecker isolcpus= [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance. 1893b0d40d2bSFrederic Weisbecker [Deprecated - use cpusets instead] 1894b0d40d2bSFrederic Weisbecker Format: [flag-list,]<cpu-list> 1895e52347bdSJani Nikula 1896b0d40d2bSFrederic Weisbecker Specify one or more CPUs to isolate from disturbances 1897b0d40d2bSFrederic Weisbecker specified in the flag list (default: domain): 1898b0d40d2bSFrederic Weisbecker 1899b0d40d2bSFrederic Weisbecker nohz 1900b0d40d2bSFrederic Weisbecker Disable the tick when a single task runs. 1901083c6eeaSFrederic Weisbecker 1902083c6eeaSFrederic Weisbecker A residual 1Hz tick is offloaded to workqueues, which you 1903083c6eeaSFrederic Weisbecker need to affine to housekeeping through the global 1904083c6eeaSFrederic Weisbecker workqueue's affinity configured via the 1905083c6eeaSFrederic Weisbecker /sys/devices/virtual/workqueue/cpumask sysfs file, or 1906083c6eeaSFrederic Weisbecker by using the 'domain' flag described below. 1907083c6eeaSFrederic Weisbecker 1908083c6eeaSFrederic Weisbecker NOTE: by default the global workqueue runs on all CPUs, 1909083c6eeaSFrederic Weisbecker so to protect individual CPUs the 'cpumask' file has to 1910083c6eeaSFrederic Weisbecker be configured manually after bootup. 1911083c6eeaSFrederic Weisbecker 1912b0d40d2bSFrederic Weisbecker domain 1913b0d40d2bSFrederic Weisbecker Isolate from the general SMP balancing and scheduling 1914b0d40d2bSFrederic Weisbecker algorithms. Note that performing domain isolation this way 1915b0d40d2bSFrederic Weisbecker is irreversible: it's not possible to bring back a CPU to 1916b0d40d2bSFrederic Weisbecker the domains once isolated through isolcpus. It's strongly 1917b0d40d2bSFrederic Weisbecker advised to use cpusets instead to disable scheduler load 1918b0d40d2bSFrederic Weisbecker balancing through the "cpuset.sched_load_balance" file. 1919b0d40d2bSFrederic Weisbecker It offers a much more flexible interface where CPUs can 1920b0d40d2bSFrederic Weisbecker move in and out of an isolated set anytime. 1921b0d40d2bSFrederic Weisbecker 1922b0d40d2bSFrederic Weisbecker You can move a process onto or off an "isolated" CPU via 1923b0d40d2bSFrederic Weisbecker the CPU affinity syscalls or cpuset. 1924e52347bdSJani Nikula <cpu number> begins at 0 and the maximum value is 1925e52347bdSJani Nikula "number of CPUs in system - 1". 1926e52347bdSJani Nikula 1927b0d40d2bSFrederic Weisbecker The format of <cpu-list> is described above. 1928b0d40d2bSFrederic Weisbecker 1929b0d40d2bSFrederic Weisbecker 1930e52347bdSJani Nikula 1931e52347bdSJani Nikula iucv= [HW,NET] 1932e52347bdSJani Nikula 1933e52347bdSJani Nikula ivrs_ioapic [HW,X86_64] 1934e52347bdSJani Nikula Provide an override to the IOAPIC-ID<->DEVICE-ID 1935e52347bdSJani Nikula mapping provided in the IVRS ACPI table. For 1936e52347bdSJani Nikula example, to map IOAPIC-ID decimal 10 to 1937e52347bdSJani Nikula PCI device 00:14.0 write the parameter as: 1938e52347bdSJani Nikula ivrs_ioapic[10]=00:14.0 1939e52347bdSJani Nikula 1940e52347bdSJani Nikula ivrs_hpet [HW,X86_64] 1941e52347bdSJani Nikula Provide an override to the HPET-ID<->DEVICE-ID 1942e52347bdSJani Nikula mapping provided in the IVRS ACPI table. For 1943e52347bdSJani Nikula example, to map HPET-ID decimal 0 to 1944e52347bdSJani Nikula PCI device 00:14.0 write the parameter as: 1945e52347bdSJani Nikula ivrs_hpet[0]=00:14.0 1946e52347bdSJani Nikula 1947e52347bdSJani Nikula ivrs_acpihid [HW,X86_64] 1948e52347bdSJani Nikula Provide an override to the ACPI-HID:UID<->DEVICE-ID 1949e52347bdSJani Nikula mapping provided in the IVRS ACPI table. For 1950e52347bdSJani Nikula example, to map UART-HID:UID AMD0020:0 to 1951e52347bdSJani Nikula PCI device 00:14.5 write the parameter as: 1952e52347bdSJani Nikula ivrs_acpihid[00:14.5]=AMD0020:0 1953e52347bdSJani Nikula 1954e52347bdSJani Nikula js= [HW,JOY] Analog joystick 19551752118dSTom Saeger See Documentation/input/joydev/joystick.rst. 1956e52347bdSJani Nikula 1957e52347bdSJani Nikula nokaslr [KNL] 1958e52347bdSJani Nikula When CONFIG_RANDOMIZE_BASE is set, this disables 1959e52347bdSJani Nikula kernel and module base offset ASLR (Address Space 1960e52347bdSJani Nikula Layout Randomization). 1961e52347bdSJani Nikula 1962b0845ce5SMark Rutland kasan_multi_shot 1963b0845ce5SMark Rutland [KNL] Enforce KASAN (Kernel Address Sanitizer) to print 1964b0845ce5SMark Rutland report on every invalid memory access. Without this 1965b0845ce5SMark Rutland parameter KASAN will print report only for the first 1966b0845ce5SMark Rutland invalid access. 1967b0845ce5SMark Rutland 1968e52347bdSJani Nikula keepinitrd [HW,ARM] 1969e52347bdSJani Nikula 1970e52347bdSJani Nikula kernelcore= [KNL,X86,IA-64,PPC] 1971a5c6d650SDavid Rientjes Format: nn[KMGTPE] | nn% | "mirror" 1972a5c6d650SDavid Rientjes This parameter specifies the amount of memory usable by 1973a5c6d650SDavid Rientjes the kernel for non-movable allocations. The requested 1974a5c6d650SDavid Rientjes amount is spread evenly throughout all nodes in the 1975a5c6d650SDavid Rientjes system as ZONE_NORMAL. The remaining memory is used for 1976a5c6d650SDavid Rientjes movable memory in its own zone, ZONE_MOVABLE. In the 1977a5c6d650SDavid Rientjes event, a node is too small to have both ZONE_NORMAL and 1978a5c6d650SDavid Rientjes ZONE_MOVABLE, kernelcore memory will take priority and 1979a5c6d650SDavid Rientjes other nodes will have a larger ZONE_MOVABLE. 1980a5c6d650SDavid Rientjes 1981a5c6d650SDavid Rientjes ZONE_MOVABLE is used for the allocation of pages that 1982a5c6d650SDavid Rientjes may be reclaimed or moved by the page migration 1983a5c6d650SDavid Rientjes subsystem. Note that allocations like PTEs-from-HighMem 1984a5c6d650SDavid Rientjes still use the HighMem zone if it exists, and the Normal 1985e52347bdSJani Nikula zone if it does not. 1986e52347bdSJani Nikula 1987a5c6d650SDavid Rientjes It is possible to specify the exact amount of memory in 1988a5c6d650SDavid Rientjes the form of "nn[KMGTPE]", a percentage of total system 1989a5c6d650SDavid Rientjes memory in the form of "nn%", or "mirror". If "mirror" 1990e52347bdSJani Nikula option is specified, mirrored (reliable) memory is used 1991e52347bdSJani Nikula for non-movable allocations and remaining memory is used 1992a5c6d650SDavid Rientjes for Movable pages. "nn[KMGTPE]", "nn%", and "mirror" 1993a5c6d650SDavid Rientjes are exclusive, so you cannot specify multiple forms. 1994e52347bdSJani Nikula 1995e52347bdSJani Nikula kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. 1996e52347bdSJani Nikula Format: <Controller#>[,poll interval] 1997e52347bdSJani Nikula The controller # is the number of the ehci usb debug 1998e52347bdSJani Nikula port as it is probed via PCI. The poll interval is 1999e52347bdSJani Nikula optional and is the number seconds in between 2000e52347bdSJani Nikula each poll cycle to the debug port in case you need 2001e52347bdSJani Nikula the functionality for interrupting the kernel with 2002e52347bdSJani Nikula gdb or control-c on the dbgp connection. When 2003e52347bdSJani Nikula not using this parameter you use sysrq-g to break into 2004e52347bdSJani Nikula the kernel debugger. 2005e52347bdSJani Nikula 2006e52347bdSJani Nikula kgdboc= [KGDB,HW] kgdb over consoles. 2007e52347bdSJani Nikula Requires a tty driver that supports console polling, 2008e52347bdSJani Nikula or a supported polling keyboard driver (non-usb). 2009e52347bdSJani Nikula Serial only format: <serial_device>[,baud] 2010e52347bdSJani Nikula keyboard only format: kbd 2011e52347bdSJani Nikula keyboard and serial format: kbd,<serial_device>[,baud] 2012e52347bdSJani Nikula Optional Kernel mode setting: 2013e52347bdSJani Nikula kms, kbd format: kms,kbd 2014e52347bdSJani Nikula kms, kbd and serial format: kms,kbd,<ser_dev>[,baud] 2015e52347bdSJani Nikula 2016e52347bdSJani Nikula kgdbwait [KGDB] Stop kernel execution and enter the 2017e52347bdSJani Nikula kernel debugger at the earliest opportunity. 2018e52347bdSJani Nikula 2019e52347bdSJani Nikula kmac= [MIPS] korina ethernet MAC address. 2020e52347bdSJani Nikula Configure the RouterBoard 532 series on-chip 2021e52347bdSJani Nikula Ethernet adapter MAC address. 2022e52347bdSJani Nikula 2023e52347bdSJani Nikula kmemleak= [KNL] Boot-time kmemleak enable/disable 2024e52347bdSJani Nikula Valid arguments: on, off 2025e52347bdSJani Nikula Default: on 2026e52347bdSJani Nikula Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, 2027e52347bdSJani Nikula the default is off. 2028e52347bdSJani Nikula 2029970988e1SMasami Hiramatsu kprobe_event=[probe-list] 2030970988e1SMasami Hiramatsu [FTRACE] Add kprobe events and enable at boot time. 2031970988e1SMasami Hiramatsu The probe-list is a semicolon delimited list of probe 2032970988e1SMasami Hiramatsu definitions. Each definition is same as kprobe_events 2033970988e1SMasami Hiramatsu interface, but the parameters are comma delimited. 2034970988e1SMasami Hiramatsu For example, to add a kprobe event on vfs_read with 2035970988e1SMasami Hiramatsu arg1 and arg2, add to the command line; 2036970988e1SMasami Hiramatsu 2037970988e1SMasami Hiramatsu kprobe_event=p,vfs_read,$arg1,$arg2 2038970988e1SMasami Hiramatsu 2039970988e1SMasami Hiramatsu See also Documentation/trace/kprobetrace.rst "Kernel 2040970988e1SMasami Hiramatsu Boot Parameter" section. 2041970988e1SMasami Hiramatsu 2042de190555SJeremy Linton kpti= [ARM64] Control page table isolation of user 2043de190555SJeremy Linton and kernel address spaces. 2044de190555SJeremy Linton Default: enabled on cores which need mitigation. 2045de190555SJeremy Linton 0: force disabled 2046de190555SJeremy Linton 1: force enabled 2047de190555SJeremy Linton 2048e52347bdSJani Nikula kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. 2049e52347bdSJani Nikula Default is 0 (don't ignore, but inject #GP) 2050e52347bdSJani Nikula 2051c4ae60e4SLiran Alon kvm.enable_vmware_backdoor=[KVM] Support VMware backdoor PV interface. 2052c4ae60e4SLiran Alon Default is false (don't support). 2053c4ae60e4SLiran Alon 2054e52347bdSJani Nikula kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit 2055e52347bdSJani Nikula KVM MMU at runtime. 2056e52347bdSJani Nikula Default is 0 (off) 2057e52347bdSJani Nikula 2058e52347bdSJani Nikula kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM. 2059e52347bdSJani Nikula Default is 1 (enabled) 2060e52347bdSJani Nikula 2061e52347bdSJani Nikula kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU) 2062e52347bdSJani Nikula for all guests. 2063e52347bdSJani Nikula Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. 2064e52347bdSJani Nikula 2065e23f62f7SMarc Zyngier kvm-arm.vgic_v3_group0_trap= 2066e23f62f7SMarc Zyngier [KVM,ARM] Trap guest accesses to GICv3 group-0 2067e23f62f7SMarc Zyngier system registers 2068e23f62f7SMarc Zyngier 2069182936eeSMarc Zyngier kvm-arm.vgic_v3_group1_trap= 2070182936eeSMarc Zyngier [KVM,ARM] Trap guest accesses to GICv3 group-1 2071182936eeSMarc Zyngier system registers 2072182936eeSMarc Zyngier 2073ff89511eSMarc Zyngier kvm-arm.vgic_v3_common_trap= 2074ff89511eSMarc Zyngier [KVM,ARM] Trap guest accesses to GICv3 common 2075ff89511eSMarc Zyngier system registers 2076ff89511eSMarc Zyngier 2077a7546054SMarc Zyngier kvm-arm.vgic_v4_enable= 2078a7546054SMarc Zyngier [KVM,ARM] Allow use of GICv4 for direct injection of 2079a7546054SMarc Zyngier LPIs. 2080a7546054SMarc Zyngier 2081e52347bdSJani Nikula kvm-intel.ept= [KVM,Intel] Disable extended page tables 2082e52347bdSJani Nikula (virtualized MMU) support on capable Intel chips. 2083e52347bdSJani Nikula Default is 1 (enabled) 2084e52347bdSJani Nikula 2085e52347bdSJani Nikula kvm-intel.emulate_invalid_guest_state= 2086e52347bdSJani Nikula [KVM,Intel] Enable emulation of invalid guest states 2087e52347bdSJani Nikula Default is 0 (disabled) 2088e52347bdSJani Nikula 2089e52347bdSJani Nikula kvm-intel.flexpriority= 2090e52347bdSJani Nikula [KVM,Intel] Disable FlexPriority feature (TPR shadow). 2091e52347bdSJani Nikula Default is 1 (enabled) 2092e52347bdSJani Nikula 2093e52347bdSJani Nikula kvm-intel.nested= 2094e52347bdSJani Nikula [KVM,Intel] Enable VMX nesting (nVMX). 2095e52347bdSJani Nikula Default is 0 (disabled) 2096e52347bdSJani Nikula 2097e52347bdSJani Nikula kvm-intel.unrestricted_guest= 2098e52347bdSJani Nikula [KVM,Intel] Disable unrestricted guest feature 2099e52347bdSJani Nikula (virtualized real and unpaged mode) on capable 2100e52347bdSJani Nikula Intel chips. Default is 1 (enabled) 2101e52347bdSJani Nikula 2102a399477eSKonrad Rzeszutek Wilk kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault 2103a399477eSKonrad Rzeszutek Wilk CVE-2018-3620. 2104a399477eSKonrad Rzeszutek Wilk 2105a399477eSKonrad Rzeszutek Wilk Valid arguments: never, cond, always 2106a399477eSKonrad Rzeszutek Wilk 2107a399477eSKonrad Rzeszutek Wilk always: L1D cache flush on every VMENTER. 2108a399477eSKonrad Rzeszutek Wilk cond: Flush L1D on VMENTER only when the code between 2109a399477eSKonrad Rzeszutek Wilk VMEXIT and VMENTER can leak host memory. 2110a399477eSKonrad Rzeszutek Wilk never: Disables the mitigation 2111a399477eSKonrad Rzeszutek Wilk 2112a399477eSKonrad Rzeszutek Wilk Default is cond (do L1 cache flush in specific instances) 2113a399477eSKonrad Rzeszutek Wilk 2114e52347bdSJani Nikula kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification 2115e52347bdSJani Nikula feature (tagged TLBs) on capable Intel chips. 2116e52347bdSJani Nikula Default is 1 (enabled) 2117e52347bdSJani Nikula 2118d90a7a0eSJiri Kosina l1tf= [X86] Control mitigation of the L1TF vulnerability on 2119d90a7a0eSJiri Kosina affected CPUs 2120d90a7a0eSJiri Kosina 2121d90a7a0eSJiri Kosina The kernel PTE inversion protection is unconditionally 2122d90a7a0eSJiri Kosina enabled and cannot be disabled. 2123d90a7a0eSJiri Kosina 2124d90a7a0eSJiri Kosina full 2125d90a7a0eSJiri Kosina Provides all available mitigations for the 2126d90a7a0eSJiri Kosina L1TF vulnerability. Disables SMT and 2127d90a7a0eSJiri Kosina enables all mitigations in the 2128d90a7a0eSJiri Kosina hypervisors, i.e. unconditional L1D flush. 2129d90a7a0eSJiri Kosina 2130d90a7a0eSJiri Kosina SMT control and L1D flush control via the 2131d90a7a0eSJiri Kosina sysfs interface is still possible after 2132d90a7a0eSJiri Kosina boot. Hypervisors will issue a warning 2133d90a7a0eSJiri Kosina when the first VM is started in a 2134d90a7a0eSJiri Kosina potentially insecure configuration, 2135d90a7a0eSJiri Kosina i.e. SMT enabled or L1D flush disabled. 2136d90a7a0eSJiri Kosina 2137d90a7a0eSJiri Kosina full,force 2138d90a7a0eSJiri Kosina Same as 'full', but disables SMT and L1D 2139d90a7a0eSJiri Kosina flush runtime control. Implies the 2140d90a7a0eSJiri Kosina 'nosmt=force' command line option. 2141d90a7a0eSJiri Kosina (i.e. sysfs control of SMT is disabled.) 2142d90a7a0eSJiri Kosina 2143d90a7a0eSJiri Kosina flush 2144d90a7a0eSJiri Kosina Leaves SMT enabled and enables the default 2145d90a7a0eSJiri Kosina hypervisor mitigation, i.e. conditional 2146d90a7a0eSJiri Kosina L1D flush. 2147d90a7a0eSJiri Kosina 2148d90a7a0eSJiri Kosina SMT control and L1D flush control via the 2149d90a7a0eSJiri Kosina sysfs interface is still possible after 2150d90a7a0eSJiri Kosina boot. Hypervisors will issue a warning 2151d90a7a0eSJiri Kosina when the first VM is started in a 2152d90a7a0eSJiri Kosina potentially insecure configuration, 2153d90a7a0eSJiri Kosina i.e. SMT enabled or L1D flush disabled. 2154d90a7a0eSJiri Kosina 2155d90a7a0eSJiri Kosina flush,nosmt 2156d90a7a0eSJiri Kosina 2157d90a7a0eSJiri Kosina Disables SMT and enables the default 2158d90a7a0eSJiri Kosina hypervisor mitigation. 2159d90a7a0eSJiri Kosina 2160d90a7a0eSJiri Kosina SMT control and L1D flush control via the 2161d90a7a0eSJiri Kosina sysfs interface is still possible after 2162d90a7a0eSJiri Kosina boot. Hypervisors will issue a warning 2163d90a7a0eSJiri Kosina when the first VM is started in a 2164d90a7a0eSJiri Kosina potentially insecure configuration, 2165d90a7a0eSJiri Kosina i.e. SMT enabled or L1D flush disabled. 2166d90a7a0eSJiri Kosina 2167d90a7a0eSJiri Kosina flush,nowarn 2168d90a7a0eSJiri Kosina Same as 'flush', but hypervisors will not 2169d90a7a0eSJiri Kosina warn when a VM is started in a potentially 2170d90a7a0eSJiri Kosina insecure configuration. 2171d90a7a0eSJiri Kosina 2172d90a7a0eSJiri Kosina off 2173d90a7a0eSJiri Kosina Disables hypervisor mitigations and doesn't 2174d90a7a0eSJiri Kosina emit any warnings. 21755b5e4d62SMichal Hocko It also drops the swap size and available 21765b5e4d62SMichal Hocko RAM limit restriction on both hypervisor and 21775b5e4d62SMichal Hocko bare metal. 2178d90a7a0eSJiri Kosina 2179d90a7a0eSJiri Kosina Default is 'flush'. 2180d90a7a0eSJiri Kosina 218165fd4cb6SThomas Gleixner For details see: Documentation/admin-guide/hw-vuln/l1tf.rst 2182d90a7a0eSJiri Kosina 2183e52347bdSJani Nikula l2cr= [PPC] 2184e52347bdSJani Nikula 2185e52347bdSJani Nikula l3cr= [PPC] 2186e52347bdSJani Nikula 2187e52347bdSJani Nikula lapic [X86-32,APIC] Enable the local APIC even if BIOS 2188e52347bdSJani Nikula disabled it. 2189e52347bdSJani Nikula 2190e52347bdSJani Nikula lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline 2191e52347bdSJani Nikula value for LAPIC timer one-shot implementation. Default 2192e52347bdSJani Nikula back to the programmable timer unit in the LAPIC. 2193e52347bdSJani Nikula 2194e52347bdSJani Nikula lapic_timer_c2_ok [X86,APIC] trust the local apic timer 2195e52347bdSJani Nikula in C2 power state. 2196e52347bdSJani Nikula 2197e52347bdSJani Nikula libata.dma= [LIBATA] DMA control 2198e52347bdSJani Nikula libata.dma=0 Disable all PATA and SATA DMA 2199e52347bdSJani Nikula libata.dma=1 PATA and SATA Disk DMA only 2200e52347bdSJani Nikula libata.dma=2 ATAPI (CDROM) DMA only 2201e52347bdSJani Nikula libata.dma=4 Compact Flash DMA only 2202e52347bdSJani Nikula Combinations also work, so libata.dma=3 enables DMA 2203e52347bdSJani Nikula for disks and CDROMs, but not CFs. 2204e52347bdSJani Nikula 2205e52347bdSJani Nikula libata.ignore_hpa= [LIBATA] Ignore HPA limit 2206e52347bdSJani Nikula libata.ignore_hpa=0 keep BIOS limits (default) 2207e52347bdSJani Nikula libata.ignore_hpa=1 ignore limits, using full disk 2208e52347bdSJani Nikula 2209e52347bdSJani Nikula libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume 2210e52347bdSJani Nikula when set. 2211e52347bdSJani Nikula Format: <int> 2212e52347bdSJani Nikula 2213e52347bdSJani Nikula libata.force= [LIBATA] Force configurations. The format is comma 2214e52347bdSJani Nikula separated list of "[ID:]VAL" where ID is 2215e52347bdSJani Nikula PORT[.DEVICE]. PORT and DEVICE are decimal numbers 2216e52347bdSJani Nikula matching port, link or device. Basically, it matches 2217e52347bdSJani Nikula the ATA ID string printed on console by libata. If 2218e52347bdSJani Nikula the whole ID part is omitted, the last PORT and DEVICE 2219e52347bdSJani Nikula values are used. If ID hasn't been specified yet, the 2220e52347bdSJani Nikula configuration applies to all ports, links and devices. 2221e52347bdSJani Nikula 2222e52347bdSJani Nikula If only DEVICE is omitted, the parameter applies to 2223e52347bdSJani Nikula the port and all links and devices behind it. DEVICE 2224e52347bdSJani Nikula number of 0 either selects the first device or the 2225e52347bdSJani Nikula first fan-out link behind PMP device. It does not 2226e52347bdSJani Nikula select the host link. DEVICE number of 15 selects the 2227e52347bdSJani Nikula host link and device attached to it. 2228e52347bdSJani Nikula 2229e52347bdSJani Nikula The VAL specifies the configuration to force. As long 2230e52347bdSJani Nikula as there's no ambiguity shortcut notation is allowed. 2231e52347bdSJani Nikula For example, both 1.5 and 1.5G would work for 1.5Gbps. 2232e52347bdSJani Nikula The following configurations can be forced. 2233e52347bdSJani Nikula 2234e52347bdSJani Nikula * Cable type: 40c, 80c, short40c, unk, ign or sata. 2235e52347bdSJani Nikula Any ID with matching PORT is used. 2236e52347bdSJani Nikula 2237e52347bdSJani Nikula * SATA link speed limit: 1.5Gbps or 3.0Gbps. 2238e52347bdSJani Nikula 2239e52347bdSJani Nikula * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. 2240e52347bdSJani Nikula udma[/][16,25,33,44,66,100,133] notation is also 2241e52347bdSJani Nikula allowed. 2242e52347bdSJani Nikula 2243e52347bdSJani Nikula * [no]ncq: Turn on or off NCQ. 2244e52347bdSJani Nikula 2245e52347bdSJani Nikula * [no]ncqtrim: Turn off queued DSM TRIM. 2246e52347bdSJani Nikula 2247e52347bdSJani Nikula * nohrst, nosrst, norst: suppress hard, soft 2248e52347bdSJani Nikula and both resets. 2249e52347bdSJani Nikula 2250e52347bdSJani Nikula * rstonce: only attempt one reset during 2251e52347bdSJani Nikula hot-unplug link recovery 2252e52347bdSJani Nikula 2253e52347bdSJani Nikula * dump_id: dump IDENTIFY data. 2254e52347bdSJani Nikula 2255e52347bdSJani Nikula * atapi_dmadir: Enable ATAPI DMADIR bridge support 2256e52347bdSJani Nikula 2257e52347bdSJani Nikula * disable: Disable this device. 2258e52347bdSJani Nikula 2259e52347bdSJani Nikula If there are multiple matching configurations changing 2260e52347bdSJani Nikula the same attribute, the last one is used. 2261e52347bdSJani Nikula 2262e52347bdSJani Nikula memblock=debug [KNL] Enable memblock debug messages. 2263e52347bdSJani Nikula 2264e52347bdSJani Nikula load_ramdisk= [RAM] List of ramdisks to load from floppy 2265e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/ramdisk.rst. 2266e52347bdSJani Nikula 2267e52347bdSJani Nikula lockd.nlm_grace_period=P [NFS] Assign grace period. 2268e52347bdSJani Nikula Format: <integer> 2269e52347bdSJani Nikula 2270e52347bdSJani Nikula lockd.nlm_tcpport=N [NFS] Assign TCP port. 2271e52347bdSJani Nikula Format: <integer> 2272e52347bdSJani Nikula 2273e52347bdSJani Nikula lockd.nlm_timeout=T [NFS] Assign timeout value. 2274e52347bdSJani Nikula Format: <integer> 2275e52347bdSJani Nikula 2276e52347bdSJani Nikula lockd.nlm_udpport=M [NFS] Assign UDP port. 2277e52347bdSJani Nikula Format: <integer> 2278e52347bdSJani Nikula 2279000d388eSMatthew Garrett lockdown= [SECURITY] 2280000d388eSMatthew Garrett { integrity | confidentiality } 2281000d388eSMatthew Garrett Enable the kernel lockdown feature. If set to 2282000d388eSMatthew Garrett integrity, kernel features that allow userland to 2283000d388eSMatthew Garrett modify the running kernel are disabled. If set to 2284000d388eSMatthew Garrett confidentiality, kernel features that allow userland 2285000d388eSMatthew Garrett to extract confidential information from the kernel 2286000d388eSMatthew Garrett are also disabled. 2287000d388eSMatthew Garrett 2288e52347bdSJani Nikula locktorture.nreaders_stress= [KNL] 2289e52347bdSJani Nikula Set the number of locking read-acquisition kthreads. 2290e52347bdSJani Nikula Defaults to being automatically set based on the 2291e52347bdSJani Nikula number of online CPUs. 2292e52347bdSJani Nikula 2293e52347bdSJani Nikula locktorture.nwriters_stress= [KNL] 2294e52347bdSJani Nikula Set the number of locking write-acquisition kthreads. 2295e52347bdSJani Nikula 2296e52347bdSJani Nikula locktorture.onoff_holdoff= [KNL] 2297e52347bdSJani Nikula Set time (s) after boot for CPU-hotplug testing. 2298e52347bdSJani Nikula 2299e52347bdSJani Nikula locktorture.onoff_interval= [KNL] 2300e52347bdSJani Nikula Set time (s) between CPU-hotplug operations, or 2301e52347bdSJani Nikula zero to disable CPU-hotplug testing. 2302e52347bdSJani Nikula 2303e52347bdSJani Nikula locktorture.shuffle_interval= [KNL] 2304e52347bdSJani Nikula Set task-shuffle interval (jiffies). Shuffling 2305e52347bdSJani Nikula tasks allows some CPUs to go into dyntick-idle 2306e52347bdSJani Nikula mode during the locktorture test. 2307e52347bdSJani Nikula 2308e52347bdSJani Nikula locktorture.shutdown_secs= [KNL] 2309e52347bdSJani Nikula Set time (s) after boot system shutdown. This 2310e52347bdSJani Nikula is useful for hands-off automated testing. 2311e52347bdSJani Nikula 2312e52347bdSJani Nikula locktorture.stat_interval= [KNL] 2313e52347bdSJani Nikula Time (s) between statistics printk()s. 2314e52347bdSJani Nikula 2315e52347bdSJani Nikula locktorture.stutter= [KNL] 2316e52347bdSJani Nikula Time (s) to stutter testing, for example, 2317e52347bdSJani Nikula specifying five seconds causes the test to run for 2318e52347bdSJani Nikula five seconds, wait for five seconds, and so on. 2319e52347bdSJani Nikula This tests the locking primitive's ability to 2320e52347bdSJani Nikula transition abruptly to and from idle. 2321e52347bdSJani Nikula 2322e52347bdSJani Nikula locktorture.torture_type= [KNL] 2323e52347bdSJani Nikula Specify the locking implementation to test. 2324e52347bdSJani Nikula 2325e52347bdSJani Nikula locktorture.verbose= [KNL] 2326e52347bdSJani Nikula Enable additional printk() statements. 2327e52347bdSJani Nikula 2328e52347bdSJani Nikula logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver 2329e52347bdSJani Nikula Format: <irq> 2330e52347bdSJani Nikula 2331e52347bdSJani Nikula loglevel= All Kernel Messages with a loglevel smaller than the 2332e52347bdSJani Nikula console loglevel will be printed to the console. It can 2333e52347bdSJani Nikula also be changed with klogd or other programs. The 2334e52347bdSJani Nikula loglevels are defined as follows: 2335e52347bdSJani Nikula 2336e52347bdSJani Nikula 0 (KERN_EMERG) system is unusable 2337e52347bdSJani Nikula 1 (KERN_ALERT) action must be taken immediately 2338e52347bdSJani Nikula 2 (KERN_CRIT) critical conditions 2339e52347bdSJani Nikula 3 (KERN_ERR) error conditions 2340e52347bdSJani Nikula 4 (KERN_WARNING) warning conditions 2341e52347bdSJani Nikula 5 (KERN_NOTICE) normal but significant condition 2342e52347bdSJani Nikula 6 (KERN_INFO) informational 2343e52347bdSJani Nikula 7 (KERN_DEBUG) debug-level messages 2344e52347bdSJani Nikula 2345e52347bdSJani Nikula log_buf_len=n[KMG] Sets the size of the printk ring buffer, 2346e52347bdSJani Nikula in bytes. n must be a power of two and greater 2347e52347bdSJani Nikula than the minimal size. The minimal size is defined 2348e52347bdSJani Nikula by LOG_BUF_SHIFT kernel config parameter. There is 2349e52347bdSJani Nikula also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter 2350e52347bdSJani Nikula that allows to increase the default size depending on 2351e52347bdSJani Nikula the number of CPUs. See init/Kconfig for more details. 2352e52347bdSJani Nikula 2353e52347bdSJani Nikula logo.nologo [FB] Disables display of the built-in Linux logo. 2354e52347bdSJani Nikula This may be used to provide more screen space for 2355e52347bdSJani Nikula kernel log messages and is useful when debugging 2356e52347bdSJani Nikula kernel boot problems. 2357e52347bdSJani Nikula 2358e52347bdSJani Nikula lp=0 [LP] Specify parallel ports to use, e.g, 2359e52347bdSJani Nikula lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 2360e52347bdSJani Nikula lp=reset first parallel port). 'lp=0' disables the 2361e52347bdSJani Nikula lp=auto printer driver. 'lp=reset' (which can be 2362e52347bdSJani Nikula specified in addition to the ports) causes 2363e52347bdSJani Nikula attached printers to be reset. Using 2364e52347bdSJani Nikula lp=port1,port2,... specifies the parallel ports 2365e52347bdSJani Nikula to associate lp devices with, starting with 2366e52347bdSJani Nikula lp0. A port specification may be 'none' to skip 2367e52347bdSJani Nikula that lp device, or a parport name such as 2368e52347bdSJani Nikula 'parport0'. Specifying 'lp=auto' instead of a 2369e52347bdSJani Nikula port specification list means that device IDs 2370e52347bdSJani Nikula from each port should be examined, to see if 2371e52347bdSJani Nikula an IEEE 1284-compliant printer is attached; if 2372e52347bdSJani Nikula so, the driver will manage that printer. 2373e52347bdSJani Nikula See also header of drivers/char/lp.c. 2374e52347bdSJani Nikula 2375e52347bdSJani Nikula lpj=n [KNL] 2376e52347bdSJani Nikula Sets loops_per_jiffy to given constant, thus avoiding 2377e52347bdSJani Nikula time-consuming boot-time autodetection (up to 250 ms per 2378e52347bdSJani Nikula CPU). 0 enables autodetection (default). To determine 2379e52347bdSJani Nikula the correct value for your kernel, boot with normal 2380e52347bdSJani Nikula autodetection and see what value is printed. Note that 2381e52347bdSJani Nikula on SMP systems the preset will be applied to all CPUs, 2382e52347bdSJani Nikula which is likely to cause problems if your CPUs need 2383e52347bdSJani Nikula significantly divergent settings. An incorrect value 2384e52347bdSJani Nikula will cause delays in the kernel to be wrong, leading to 2385e52347bdSJani Nikula unpredictable I/O errors and other breakage. Although 2386e52347bdSJani Nikula unlikely, in the extreme case this might damage your 2387e52347bdSJani Nikula hardware. 2388e52347bdSJani Nikula 2389e52347bdSJani Nikula ltpc= [NET] 2390e52347bdSJani Nikula Format: <io>,<irq>,<dma> 2391e52347bdSJani Nikula 23929b8c7c14SKees Cook lsm.debug [SECURITY] Enable LSM initialization debugging output. 23939b8c7c14SKees Cook 239479f7865dSKees Cook lsm=lsm1,...,lsmN 239579f7865dSKees Cook [SECURITY] Choose order of LSM initialization. This 239689a9684eSKees Cook overrides CONFIG_LSM, and the "security=" parameter. 239779f7865dSKees Cook 2398e52347bdSJani Nikula machvec= [IA-64] Force the use of a particular machine-vector 2399e52347bdSJani Nikula (machvec) in a generic kernel. 2400df43acacSChristoph Hellwig Example: machvec=hpzx1 2401e52347bdSJani Nikula 2402e52347bdSJani Nikula machtype= [Loongson] Share the same kernel image file between different 2403e52347bdSJani Nikula yeeloong laptop. 2404e52347bdSJani Nikula Example: machtype=lemote-yeeloong-2f-7inch 2405e52347bdSJani Nikula 2406e52347bdSJani Nikula max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater 2407e52347bdSJani Nikula than or equal to this physical address is ignored. 2408e52347bdSJani Nikula 2409e52347bdSJani Nikula maxcpus= [SMP] Maximum number of processors that an SMP kernel 2410e52347bdSJani Nikula will bring up during bootup. maxcpus=n : n >= 0 limits 2411e52347bdSJani Nikula the kernel to bring up 'n' processors. Surely after 2412e52347bdSJani Nikula bootup you can bring up the other plugged cpu by executing 2413e52347bdSJani Nikula "echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus 2414e52347bdSJani Nikula only takes effect during system bootup. 2415e52347bdSJani Nikula While n=0 is a special case, it is equivalent to "nosmp", 2416e52347bdSJani Nikula which also disables the IO APIC. 2417e52347bdSJani Nikula 2418e52347bdSJani Nikula max_loop= [LOOP] The number of loop block devices that get 2419e52347bdSJani Nikula (loop.max_loop) unconditionally pre-created at init time. The default 2420e52347bdSJani Nikula number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead 2421e52347bdSJani Nikula of statically allocating a predefined number, loop 2422e52347bdSJani Nikula devices can be requested on-demand with the 2423e52347bdSJani Nikula /dev/loop-control interface. 2424e52347bdSJani Nikula 2425e52347bdSJani Nikula mce [X86-32] Machine Check Exception 2426e52347bdSJani Nikula 2427cb1aaebeSMauro Carvalho Chehab mce=option [X86-64] See Documentation/x86/x86_64/boot-options.rst 2428e52347bdSJani Nikula 2429e52347bdSJani Nikula md= [HW] RAID subsystems devices and level 2430e52347bdSJani Nikula See Documentation/admin-guide/md.rst. 2431e52347bdSJani Nikula 2432e52347bdSJani Nikula mdacon= [MDA] 2433e52347bdSJani Nikula Format: <first>,<last> 2434e52347bdSJani Nikula Specifies range of consoles to be captured by the MDA. 2435e52347bdSJani Nikula 2436bc124170SThomas Gleixner mds= [X86,INTEL] 2437bc124170SThomas Gleixner Control mitigation for the Micro-architectural Data 2438bc124170SThomas Gleixner Sampling (MDS) vulnerability. 2439bc124170SThomas Gleixner 2440bc124170SThomas Gleixner Certain CPUs are vulnerable to an exploit against CPU 2441bc124170SThomas Gleixner internal buffers which can forward information to a 2442bc124170SThomas Gleixner disclosure gadget under certain conditions. 2443bc124170SThomas Gleixner 2444bc124170SThomas Gleixner In vulnerable processors, the speculatively 2445bc124170SThomas Gleixner forwarded data can be used in a cache side channel 2446bc124170SThomas Gleixner attack, to access data to which the attacker does 2447bc124170SThomas Gleixner not have direct access. 2448bc124170SThomas Gleixner 2449bc124170SThomas Gleixner This parameter controls the MDS mitigation. The 2450bc124170SThomas Gleixner options are: 2451bc124170SThomas Gleixner 2452bc124170SThomas Gleixner full - Enable MDS mitigation on vulnerable CPUs 2453d71eb0ceSJosh Poimboeuf full,nosmt - Enable MDS mitigation and disable 2454d71eb0ceSJosh Poimboeuf SMT on vulnerable CPUs 2455bc124170SThomas Gleixner off - Unconditionally disable MDS mitigation 2456bc124170SThomas Gleixner 2457bc124170SThomas Gleixner Not specifying this option is equivalent to 2458bc124170SThomas Gleixner mds=full. 2459bc124170SThomas Gleixner 24605999bbe7SThomas Gleixner For details see: Documentation/admin-guide/hw-vuln/mds.rst 24615999bbe7SThomas Gleixner 2462e52347bdSJani Nikula mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory 2463e52347bdSJani Nikula Amount of memory to be used when the kernel is not able 2464e52347bdSJani Nikula to see the whole system memory or for test. 2465e52347bdSJani Nikula [X86] Work as limiting max address. Use together 2466e52347bdSJani Nikula with memmap= to avoid physical address space collisions. 2467e52347bdSJani Nikula Without memmap= PCI devices could be placed at addresses 2468e52347bdSJani Nikula belonging to unused RAM. 2469e52347bdSJani Nikula 2470e52347bdSJani Nikula mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel 2471e52347bdSJani Nikula memory. 2472e52347bdSJani Nikula 2473e52347bdSJani Nikula memchunk=nn[KMG] 2474e52347bdSJani Nikula [KNL,SH] Allow user to override the default size for 2475e52347bdSJani Nikula per-device physically contiguous DMA buffers. 2476e52347bdSJani Nikula 2477e52347bdSJani Nikula memhp_default_state=online/offline 2478e52347bdSJani Nikula [KNL] Set the initial state for the memory hotplug 2479e52347bdSJani Nikula onlining policy. If not specified, the default value is 2480e52347bdSJani Nikula set according to the 2481e52347bdSJani Nikula CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config 2482e52347bdSJani Nikula option. 2483cb1aaebeSMauro Carvalho Chehab See Documentation/admin-guide/mm/memory-hotplug.rst. 2484e52347bdSJani Nikula 2485e52347bdSJani Nikula memmap=exactmap [KNL,X86] Enable setting of an exact 2486e52347bdSJani Nikula E820 memory map, as specified by the user. 2487e52347bdSJani Nikula Such memmap=exactmap lines can be constructed based on 2488e52347bdSJani Nikula BIOS output or other requirements. See the memmap=nn@ss 2489e52347bdSJani Nikula option description. 2490e52347bdSJani Nikula 2491e52347bdSJani Nikula memmap=nn[KMG]@ss[KMG] 2492e52347bdSJani Nikula [KNL] Force usage of a specific region of memory. 2493e52347bdSJani Nikula Region of memory to be used is from ss to ss+nn. 24948fcc9bc3SBaoquan He If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG], 24958fcc9bc3SBaoquan He which limits max address to nn[KMG]. 24968fcc9bc3SBaoquan He Multiple different regions can be specified, 24978fcc9bc3SBaoquan He comma delimited. 24988fcc9bc3SBaoquan He Example: 24998fcc9bc3SBaoquan He memmap=100M@2G,100M#3G,1G!1024G 2500e52347bdSJani Nikula 2501e52347bdSJani Nikula memmap=nn[KMG]#ss[KMG] 2502e52347bdSJani Nikula [KNL,ACPI] Mark specific memory as ACPI data. 2503e52347bdSJani Nikula Region of memory to be marked is from ss to ss+nn. 2504e52347bdSJani Nikula 2505e52347bdSJani Nikula memmap=nn[KMG]$ss[KMG] 2506e52347bdSJani Nikula [KNL,ACPI] Mark specific memory as reserved. 2507e52347bdSJani Nikula Region of memory to be reserved is from ss to ss+nn. 2508e52347bdSJani Nikula Example: Exclude memory from 0x18690000-0x1869ffff 2509e52347bdSJani Nikula memmap=64K$0x18690000 2510e52347bdSJani Nikula or 2511e52347bdSJani Nikula memmap=0x10000$0x18690000 25128fcc9bc3SBaoquan He Some bootloaders may need an escape character before '$', 25138fcc9bc3SBaoquan He like Grub2, otherwise '$' and the following number 25148fcc9bc3SBaoquan He will be eaten. 2515e52347bdSJani Nikula 2516e52347bdSJani Nikula memmap=nn[KMG]!ss[KMG] 2517e52347bdSJani Nikula [KNL,X86] Mark specific memory as protected. 2518e52347bdSJani Nikula Region of memory to be used, from ss to ss+nn. 2519e52347bdSJani Nikula The memory region may be marked as e820 type 12 (0xc) 2520e52347bdSJani Nikula and is NVDIMM or ADR memory. 2521e52347bdSJani Nikula 2522ef61f8a3SJan H. Schönherr memmap=<size>%<offset>-<oldtype>+<newtype> 2523ef61f8a3SJan H. Schönherr [KNL,ACPI] Convert memory within the specified region 2524ef61f8a3SJan H. Schönherr from <oldtype> to <newtype>. If "-<oldtype>" is left 2525ef61f8a3SJan H. Schönherr out, the whole region will be marked as <newtype>, 2526ef61f8a3SJan H. Schönherr even if previously unavailable. If "+<newtype>" is left 2527ef61f8a3SJan H. Schönherr out, matching memory will be removed. Types are 2528ef61f8a3SJan H. Schönherr specified as e820 types, e.g., 1 = RAM, 2 = reserved, 2529ef61f8a3SJan H. Schönherr 3 = ACPI, 12 = PRAM. 2530ef61f8a3SJan H. Schönherr 2531e52347bdSJani Nikula memory_corruption_check=0/1 [X86] 2532e52347bdSJani Nikula Some BIOSes seem to corrupt the first 64k of 2533e52347bdSJani Nikula memory when doing things like suspend/resume. 2534e52347bdSJani Nikula Setting this option will scan the memory 2535e52347bdSJani Nikula looking for corruption. Enabling this will 2536e52347bdSJani Nikula both detect corruption and prevent the kernel 2537e52347bdSJani Nikula from using the memory being corrupted. 2538e52347bdSJani Nikula However, its intended as a diagnostic tool; if 2539e52347bdSJani Nikula repeatable BIOS-originated corruption always 2540e52347bdSJani Nikula affects the same memory, you can use memmap= 2541e52347bdSJani Nikula to prevent the kernel from using that memory. 2542e52347bdSJani Nikula 2543e52347bdSJani Nikula memory_corruption_check_size=size [X86] 2544e52347bdSJani Nikula By default it checks for corruption in the low 2545e52347bdSJani Nikula 64k, making this memory unavailable for normal 2546e52347bdSJani Nikula use. Use this parameter to scan for 2547e52347bdSJani Nikula corruption in more or less memory. 2548e52347bdSJani Nikula 2549e52347bdSJani Nikula memory_corruption_check_period=seconds [X86] 2550e52347bdSJani Nikula By default it checks for corruption every 60 2551e52347bdSJani Nikula seconds. Use this parameter to check at some 2552e52347bdSJani Nikula other rate. 0 disables periodic checking. 2553e52347bdSJani Nikula 2554d90fe2acSChristophe Leroy memtest= [KNL,X86,ARM,PPC] Enable memtest 2555e52347bdSJani Nikula Format: <integer> 2556e52347bdSJani Nikula default : 0 <disable> 2557e52347bdSJani Nikula Specifies the number of memtest passes to be 2558e52347bdSJani Nikula performed. Each pass selects another test 2559e52347bdSJani Nikula pattern from a given set of patterns. Memtest 2560e52347bdSJani Nikula fills the memory with this pattern, validates 2561e52347bdSJani Nikula memory contents and reserves bad memory 2562e52347bdSJani Nikula regions that are detected. 2563e52347bdSJani Nikula 2564c262f3b9STom Lendacky mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control 2565c262f3b9STom Lendacky Valid arguments: on, off 2566c262f3b9STom Lendacky Default (depends on kernel configuration option): 2567c262f3b9STom Lendacky on (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y) 2568c262f3b9STom Lendacky off (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n) 2569c262f3b9STom Lendacky mem_encrypt=on: Activate SME 2570c262f3b9STom Lendacky mem_encrypt=off: Do not activate SME 2571c262f3b9STom Lendacky 25722f5947dfSChristoph Hellwig Refer to Documentation/virt/kvm/amd-memory-encryption.rst 2573c262f3b9STom Lendacky for details on when memory encryption can be activated. 2574c262f3b9STom Lendacky 25757b9dc3f7SLinus Torvalds mem_sleep_default= [SUSPEND] Default system suspend mode: 25767b9dc3f7SLinus Torvalds s2idle - Suspend-To-Idle 25777b9dc3f7SLinus Torvalds shallow - Power-On Suspend or equivalent (if supported) 25787b9dc3f7SLinus Torvalds deep - Suspend-To-RAM or equivalent (if supported) 257958e7cb9eSRafael J. Wysocki See Documentation/admin-guide/pm/sleep-states.rst. 25807b9dc3f7SLinus Torvalds 2581e52347bdSJani Nikula meye.*= [HW] Set MotionEye Camera parameters 2582a405ed85STom Saeger See Documentation/media/v4l-drivers/meye.rst. 2583e52347bdSJani Nikula 2584e52347bdSJani Nikula mfgpt_irq= [IA-32] Specify the IRQ to use for the 2585e52347bdSJani Nikula Multi-Function General Purpose Timers on AMD Geode 2586e52347bdSJani Nikula platforms. 2587e52347bdSJani Nikula 2588e52347bdSJani Nikula mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when 2589e52347bdSJani Nikula the BIOS has incorrectly applied a workaround. TinyBIOS 2590e52347bdSJani Nikula version 0.98 is known to be affected, 0.99 fixes the 2591e52347bdSJani Nikula problem by letting the user disable the workaround. 2592e52347bdSJani Nikula 2593e52347bdSJani Nikula mga= [HW,DRM] 2594e52347bdSJani Nikula 2595e52347bdSJani Nikula min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this 2596e52347bdSJani Nikula physical address is ignored. 2597e52347bdSJani Nikula 2598e52347bdSJani Nikula mini2440= [ARM,HW,KNL] 2599e52347bdSJani Nikula Format:[0..2][b][c][t] 2600e52347bdSJani Nikula Default: "0tb" 2601e52347bdSJani Nikula MINI2440 configuration specification: 2602e52347bdSJani Nikula 0 - The attached screen is the 3.5" TFT 2603e52347bdSJani Nikula 1 - The attached screen is the 7" TFT 2604e52347bdSJani Nikula 2 - The VGA Shield is attached (1024x768) 2605e52347bdSJani Nikula Leaving out the screen size parameter will not load 2606e52347bdSJani Nikula the TFT driver, and the framebuffer will be left 2607e52347bdSJani Nikula unconfigured. 2608e52347bdSJani Nikula b - Enable backlight. The TFT backlight pin will be 2609e52347bdSJani Nikula linked to the kernel VESA blanking code and a GPIO 2610e52347bdSJani Nikula LED. This parameter is not necessary when using the 2611e52347bdSJani Nikula VGA shield. 2612e52347bdSJani Nikula c - Enable the s3c camera interface. 2613e52347bdSJani Nikula t - Reserved for enabling touchscreen support. The 2614e52347bdSJani Nikula touchscreen support is not enabled in the mainstream 2615e52347bdSJani Nikula kernel as of 2.6.30, a preliminary port can be found 2616e52347bdSJani Nikula in the "bleeding edge" mini2440 support kernel at 2617e52347bdSJani Nikula http://repo.or.cz/w/linux-2.6/mini2440.git 2618e52347bdSJani Nikula 261998af8452SJosh Poimboeuf mitigations= 2620a111b7c0SJosh Poimboeuf [X86,PPC,S390,ARM64] Control optional mitigations for 2621a111b7c0SJosh Poimboeuf CPU vulnerabilities. This is a set of curated, 2622d68be4c4SJosh Poimboeuf arch-independent options, each of which is an 2623d68be4c4SJosh Poimboeuf aggregation of existing arch-specific options. 262498af8452SJosh Poimboeuf 262598af8452SJosh Poimboeuf off 262698af8452SJosh Poimboeuf Disable all optional CPU mitigations. This 262798af8452SJosh Poimboeuf improves system performance, but it may also 262898af8452SJosh Poimboeuf expose users to several CPU vulnerabilities. 2629782e69efSJosh Poimboeuf Equivalent to: nopti [X86,PPC] 2630a111b7c0SJosh Poimboeuf kpti=0 [ARM64] 2631a2059825SJosh Poimboeuf nospectre_v1 [X86,PPC] 26320336e04aSJosh Poimboeuf nobp=0 [S390] 2633a111b7c0SJosh Poimboeuf nospectre_v2 [X86,PPC,S390,ARM64] 2634d68be4c4SJosh Poimboeuf spectre_v2_user=off [X86] 2635782e69efSJosh Poimboeuf spec_store_bypass_disable=off [X86,PPC] 2636a111b7c0SJosh Poimboeuf ssbd=force-off [ARM64] 2637d68be4c4SJosh Poimboeuf l1tf=off [X86] 26385c14068fSJosh Poimboeuf mds=off [X86] 263998af8452SJosh Poimboeuf 264098af8452SJosh Poimboeuf auto (default) 264198af8452SJosh Poimboeuf Mitigate all CPU vulnerabilities, but leave SMT 264298af8452SJosh Poimboeuf enabled, even if it's vulnerable. This is for 264398af8452SJosh Poimboeuf users who don't want to be surprised by SMT 264498af8452SJosh Poimboeuf getting disabled across kernel upgrades, or who 264598af8452SJosh Poimboeuf have other ways of avoiding SMT-based attacks. 2646d68be4c4SJosh Poimboeuf Equivalent to: (default behavior) 264798af8452SJosh Poimboeuf 264898af8452SJosh Poimboeuf auto,nosmt 264998af8452SJosh Poimboeuf Mitigate all CPU vulnerabilities, disabling SMT 265098af8452SJosh Poimboeuf if needed. This is for users who always want to 265198af8452SJosh Poimboeuf be fully mitigated, even if it means losing SMT. 2652d68be4c4SJosh Poimboeuf Equivalent to: l1tf=flush,nosmt [X86] 26535c14068fSJosh Poimboeuf mds=full,nosmt [X86] 265498af8452SJosh Poimboeuf 2655e52347bdSJani Nikula mminit_loglevel= 2656e52347bdSJani Nikula [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this 2657e52347bdSJani Nikula parameter allows control of the logging verbosity for 2658e52347bdSJani Nikula the additional memory initialisation checks. A value 2659e52347bdSJani Nikula of 0 disables mminit logging and a level of 4 will 2660e52347bdSJani Nikula log everything. Information is printed at KERN_DEBUG 2661e52347bdSJani Nikula so loglevel=8 may also need to be specified. 2662e52347bdSJani Nikula 2663e52347bdSJani Nikula module.sig_enforce 2664e52347bdSJani Nikula [KNL] When CONFIG_MODULE_SIG is set, this means that 2665e52347bdSJani Nikula modules without (valid) signatures will fail to load. 2666e52347bdSJani Nikula Note that if CONFIG_MODULE_SIG_FORCE is set, that 2667e52347bdSJani Nikula is always true, so this option does nothing. 2668e52347bdSJani Nikula 2669e52347bdSJani Nikula module_blacklist= [KNL] Do not load a comma-separated list of 2670e52347bdSJani Nikula modules. Useful for debugging problem modules. 2671e52347bdSJani Nikula 2672e52347bdSJani Nikula mousedev.tap_time= 2673e52347bdSJani Nikula [MOUSE] Maximum time between finger touching and 2674e52347bdSJani Nikula leaving touchpad surface for touch to be considered 2675e52347bdSJani Nikula a tap and be reported as a left button click (for 2676e52347bdSJani Nikula touchpads working in absolute mode only). 2677e52347bdSJani Nikula Format: <msecs> 2678e52347bdSJani Nikula mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices 2679e52347bdSJani Nikula reporting absolute coordinates, such as tablets 2680e52347bdSJani Nikula mousedev.yres= [MOUSE] Vertical screen resolution, used for devices 2681e52347bdSJani Nikula reporting absolute coordinates, such as tablets 2682e52347bdSJani Nikula 2683a5c6d650SDavid Rientjes movablecore= [KNL,X86,IA-64,PPC] 2684a5c6d650SDavid Rientjes Format: nn[KMGTPE] | nn% 2685a5c6d650SDavid Rientjes This parameter is the complement to kernelcore=, it 2686a5c6d650SDavid Rientjes specifies the amount of memory used for migratable 2687a5c6d650SDavid Rientjes allocations. If both kernelcore and movablecore is 2688a5c6d650SDavid Rientjes specified, then kernelcore will be at *least* the 2689a5c6d650SDavid Rientjes specified value but may be more. If movablecore on its 2690a5c6d650SDavid Rientjes own is specified, the administrator must be careful 2691e52347bdSJani Nikula that the amount of memory usable for all allocations 2692e52347bdSJani Nikula is not too small. 2693e52347bdSJani Nikula 2694f70029bbSMichal Hocko movable_node [KNL] Boot-time switch to make hotplugable memory 2695f70029bbSMichal Hocko NUMA nodes to be movable. This means that the memory 2696f70029bbSMichal Hocko of such nodes will be usable only for movable 2697f70029bbSMichal Hocko allocations which rules out almost all kernel 2698f70029bbSMichal Hocko allocations. Use with caution! 2699e52347bdSJani Nikula 2700e52347bdSJani Nikula MTD_Partition= [MTD] 2701e52347bdSJani Nikula Format: <name>,<region-number>,<size>,<offset> 2702e52347bdSJani Nikula 2703e52347bdSJani Nikula MTD_Region= [MTD] Format: 2704e52347bdSJani Nikula <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] 2705e52347bdSJani Nikula 2706e52347bdSJani Nikula mtdparts= [MTD] 2707e52347bdSJani Nikula See drivers/mtd/cmdlinepart.c. 2708e52347bdSJani Nikula 2709e52347bdSJani Nikula multitce=off [PPC] This parameter disables the use of the pSeries 2710e52347bdSJani Nikula firmware feature for updating multiple TCE entries 2711e52347bdSJani Nikula at a time. 2712e52347bdSJani Nikula 2713e52347bdSJani Nikula onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration 2714e52347bdSJani Nikula 2715e52347bdSJani Nikula Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] 2716e52347bdSJani Nikula 2717e52347bdSJani Nikula boundary - index of last SLC block on Flex-OneNAND. 2718e52347bdSJani Nikula The remaining blocks are configured as MLC blocks. 2719e52347bdSJani Nikula lock - Configure if Flex-OneNAND boundary should be locked. 2720e52347bdSJani Nikula Once locked, the boundary cannot be changed. 2721e52347bdSJani Nikula 1 indicates lock status, 0 indicates unlock status. 2722e52347bdSJani Nikula 2723e52347bdSJani Nikula mtdset= [ARM] 2724e52347bdSJani Nikula ARM/S3C2412 JIVE boot control 2725e52347bdSJani Nikula 2726e52347bdSJani Nikula See arch/arm/mach-s3c2412/mach-jive.c 2727e52347bdSJani Nikula 2728e52347bdSJani Nikula mtouchusb.raw_coordinates= 2729e52347bdSJani Nikula [HW] Make the MicroTouch USB driver use raw coordinates 2730e52347bdSJani Nikula ('y', default) or cooked coordinates ('n') 2731e52347bdSJani Nikula 2732e52347bdSJani Nikula mtrr_chunk_size=nn[KMG] [X86] 2733e52347bdSJani Nikula used for mtrr cleanup. It is largest continuous chunk 2734e52347bdSJani Nikula that could hold holes aka. UC entries. 2735e52347bdSJani Nikula 2736e52347bdSJani Nikula mtrr_gran_size=nn[KMG] [X86] 2737e52347bdSJani Nikula Used for mtrr cleanup. It is granularity of mtrr block. 2738e52347bdSJani Nikula Default is 1. 2739e52347bdSJani Nikula Large value could prevent small alignment from 2740e52347bdSJani Nikula using up MTRRs. 2741e52347bdSJani Nikula 2742e52347bdSJani Nikula mtrr_spare_reg_nr=n [X86] 2743e52347bdSJani Nikula Format: <integer> 2744e52347bdSJani Nikula Range: 0,7 : spare reg number 2745e52347bdSJani Nikula Default : 1 2746e52347bdSJani Nikula Used for mtrr cleanup. It is spare mtrr entries number. 2747e52347bdSJani Nikula Set to 2 or more if your graphical card needs more. 2748e52347bdSJani Nikula 2749e52347bdSJani Nikula n2= [NET] SDL Inc. RISCom/N2 synchronous serial card 2750e52347bdSJani Nikula 2751e52347bdSJani Nikula netdev= [NET] Network devices parameters 2752e52347bdSJani Nikula Format: <irq>,<io>,<mem_start>,<mem_end>,<name> 2753e52347bdSJani Nikula Note that mem_start is often overloaded to mean 2754e52347bdSJani Nikula something different and driver-specific. 2755e52347bdSJani Nikula This usage is only documented in each driver source 2756e52347bdSJani Nikula file if at all. 2757e52347bdSJani Nikula 2758e52347bdSJani Nikula nf_conntrack.acct= 2759e52347bdSJani Nikula [NETFILTER] Enable connection tracking flow accounting 2760e52347bdSJani Nikula 0 to disable accounting 2761e52347bdSJani Nikula 1 to enable accounting 2762e52347bdSJani Nikula Default value is 0. 2763e52347bdSJani Nikula 2764e52347bdSJani Nikula nfsaddrs= [NFS] Deprecated. Use ip= instead. 2765e52347bdSJani Nikula See Documentation/filesystems/nfs/nfsroot.txt. 2766e52347bdSJani Nikula 2767e52347bdSJani Nikula nfsroot= [NFS] nfs root filesystem for disk-less boxes. 2768e52347bdSJani Nikula See Documentation/filesystems/nfs/nfsroot.txt. 2769e52347bdSJani Nikula 2770e52347bdSJani Nikula nfsrootdebug [NFS] enable nfsroot debugging messages. 2771e52347bdSJani Nikula See Documentation/filesystems/nfs/nfsroot.txt. 2772e52347bdSJani Nikula 2773e52347bdSJani Nikula nfs.callback_nr_threads= 2774e52347bdSJani Nikula [NFSv4] set the total number of threads that the 2775e52347bdSJani Nikula NFS client will assign to service NFSv4 callback 2776e52347bdSJani Nikula requests. 2777e52347bdSJani Nikula 2778e52347bdSJani Nikula nfs.callback_tcpport= 2779e52347bdSJani Nikula [NFS] set the TCP port on which the NFSv4 callback 2780e52347bdSJani Nikula channel should listen. 2781e52347bdSJani Nikula 2782e52347bdSJani Nikula nfs.cache_getent= 2783e52347bdSJani Nikula [NFS] sets the pathname to the program which is used 2784e52347bdSJani Nikula to update the NFS client cache entries. 2785e52347bdSJani Nikula 2786e52347bdSJani Nikula nfs.cache_getent_timeout= 2787e52347bdSJani Nikula [NFS] sets the timeout after which an attempt to 2788e52347bdSJani Nikula update a cache entry is deemed to have failed. 2789e52347bdSJani Nikula 2790e52347bdSJani Nikula nfs.idmap_cache_timeout= 2791e52347bdSJani Nikula [NFS] set the maximum lifetime for idmapper cache 2792e52347bdSJani Nikula entries. 2793e52347bdSJani Nikula 2794e52347bdSJani Nikula nfs.enable_ino64= 2795e52347bdSJani Nikula [NFS] enable 64-bit inode numbers. 2796e52347bdSJani Nikula If zero, the NFS client will fake up a 32-bit inode 2797e52347bdSJani Nikula number for the readdir() and stat() syscalls instead 2798e52347bdSJani Nikula of returning the full 64-bit number. 2799e52347bdSJani Nikula The default is to return 64-bit inode numbers. 2800e52347bdSJani Nikula 2801e52347bdSJani Nikula nfs.max_session_cb_slots= 2802e52347bdSJani Nikula [NFSv4.1] Sets the maximum number of session 2803e52347bdSJani Nikula slots the client will assign to the callback 2804e52347bdSJani Nikula channel. This determines the maximum number of 2805e52347bdSJani Nikula callbacks the client will process in parallel for 2806e52347bdSJani Nikula a particular server. 2807e52347bdSJani Nikula 2808e52347bdSJani Nikula nfs.max_session_slots= 2809e52347bdSJani Nikula [NFSv4.1] Sets the maximum number of session slots 2810e52347bdSJani Nikula the client will attempt to negotiate with the server. 2811e52347bdSJani Nikula This limits the number of simultaneous RPC requests 2812e52347bdSJani Nikula that the client can send to the NFSv4.1 server. 2813e52347bdSJani Nikula Note that there is little point in setting this 2814e52347bdSJani Nikula value higher than the max_tcp_slot_table_limit. 2815e52347bdSJani Nikula 2816e52347bdSJani Nikula nfs.nfs4_disable_idmapping= 2817e52347bdSJani Nikula [NFSv4] When set to the default of '1', this option 2818e52347bdSJani Nikula ensures that both the RPC level authentication 2819e52347bdSJani Nikula scheme and the NFS level operations agree to use 2820e52347bdSJani Nikula numeric uids/gids if the mount is using the 2821e52347bdSJani Nikula 'sec=sys' security flavour. In effect it is 2822e52347bdSJani Nikula disabling idmapping, which can make migration from 2823e52347bdSJani Nikula legacy NFSv2/v3 systems to NFSv4 easier. 2824e52347bdSJani Nikula Servers that do not support this mode of operation 2825e52347bdSJani Nikula will be autodetected by the client, and it will fall 2826e52347bdSJani Nikula back to using the idmapper. 2827e52347bdSJani Nikula To turn off this behaviour, set the value to '0'. 2828e52347bdSJani Nikula nfs.nfs4_unique_id= 2829e52347bdSJani Nikula [NFS4] Specify an additional fixed unique ident- 2830e52347bdSJani Nikula ification string that NFSv4 clients can insert into 2831e52347bdSJani Nikula their nfs_client_id4 string. This is typically a 2832e52347bdSJani Nikula UUID that is generated at system install time. 2833e52347bdSJani Nikula 2834e52347bdSJani Nikula nfs.send_implementation_id = 2835e52347bdSJani Nikula [NFSv4.1] Send client implementation identification 2836e52347bdSJani Nikula information in exchange_id requests. 2837e52347bdSJani Nikula If zero, no implementation identification information 2838e52347bdSJani Nikula will be sent. 2839e52347bdSJani Nikula The default is to send the implementation identification 2840e52347bdSJani Nikula information. 2841e52347bdSJani Nikula 2842e52347bdSJani Nikula nfs.recover_lost_locks = 2843e52347bdSJani Nikula [NFSv4] Attempt to recover locks that were lost due 2844e52347bdSJani Nikula to a lease timeout on the server. Please note that 2845e52347bdSJani Nikula doing this risks data corruption, since there are 2846e52347bdSJani Nikula no guarantees that the file will remain unchanged 2847e52347bdSJani Nikula after the locks are lost. 2848e52347bdSJani Nikula If you want to enable the kernel legacy behaviour of 2849e52347bdSJani Nikula attempting to recover these locks, then set this 2850e52347bdSJani Nikula parameter to '1'. 2851e52347bdSJani Nikula The default parameter value of '0' causes the kernel 2852e52347bdSJani Nikula not to attempt recovery of lost locks. 2853e52347bdSJani Nikula 2854e52347bdSJani Nikula nfs4.layoutstats_timer = 2855e52347bdSJani Nikula [NFSv4.2] Change the rate at which the kernel sends 2856e52347bdSJani Nikula layoutstats to the pNFS metadata server. 2857e52347bdSJani Nikula 2858e52347bdSJani Nikula Setting this to value to 0 causes the kernel to use 2859e52347bdSJani Nikula whatever value is the default set by the layout 2860e52347bdSJani Nikula driver. A non-zero value sets the minimum interval 2861e52347bdSJani Nikula in seconds between layoutstats transmissions. 2862e52347bdSJani Nikula 2863e52347bdSJani Nikula nfsd.nfs4_disable_idmapping= 2864e52347bdSJani Nikula [NFSv4] When set to the default of '1', the NFSv4 2865e52347bdSJani Nikula server will return only numeric uids and gids to 2866e52347bdSJani Nikula clients using auth_sys, and will accept numeric uids 2867e52347bdSJani Nikula and gids from such clients. This is intended to ease 2868e52347bdSJani Nikula migration from NFSv2/v3. 2869e52347bdSJani Nikula 2870c0c74acbSHans-Christian Noren Egtvedt nmi_debug= [KNL,SH] Specify one or more actions to take 2871e52347bdSJani Nikula when a NMI is triggered. 2872e52347bdSJani Nikula Format: [state][,regs][,debounce][,die] 2873e52347bdSJani Nikula 2874e52347bdSJani Nikula nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels 2875e52347bdSJani Nikula Format: [panic,][nopanic,][num] 2876e52347bdSJani Nikula Valid num: 0 or 1 2877e52347bdSJani Nikula 0 - turn hardlockup detector in nmi_watchdog off 2878e52347bdSJani Nikula 1 - turn hardlockup detector in nmi_watchdog on 2879e52347bdSJani Nikula When panic is specified, panic when an NMI watchdog 288093285c01SZhenzhong Duan timeout occurs (or 'nopanic' to not panic on an NMI 288193285c01SZhenzhong Duan watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set) 288293285c01SZhenzhong Duan To disable both hard and soft lockup detectors, 2883e52347bdSJani Nikula please see 'nowatchdog'. 2884e52347bdSJani Nikula This is useful when you use a panic=... timeout and 2885e52347bdSJani Nikula need the box quickly up again. 2886e52347bdSJani Nikula 2887d22881dcSScott Wood These settings can be accessed at runtime via 2888d22881dcSScott Wood the nmi_watchdog and hardlockup_panic sysctls. 2889d22881dcSScott Wood 2890e52347bdSJani Nikula netpoll.carrier_timeout= 2891e52347bdSJani Nikula [NET] Specifies amount of time (in seconds) that 2892e52347bdSJani Nikula netpoll should wait for a carrier. By default netpoll 2893e52347bdSJani Nikula waits 4 seconds. 2894e52347bdSJani Nikula 2895e52347bdSJani Nikula no387 [BUGS=X86-32] Tells the kernel to use the 387 maths 2896e52347bdSJani Nikula emulation library even if a 387 maths coprocessor 2897e52347bdSJani Nikula is present. 2898e52347bdSJani Nikula 2899372fddf7SKirill A. Shutemov no5lvl [X86-64] Disable 5-level paging mode. Forces 2900372fddf7SKirill A. Shutemov kernel to use 4-level paging instead. 2901372fddf7SKirill A. Shutemov 2902e52347bdSJani Nikula no_console_suspend 2903e52347bdSJani Nikula [HW] Never suspend the console 2904e52347bdSJani Nikula Disable suspending of consoles during suspend and 2905e52347bdSJani Nikula hibernate operations. Once disabled, debugging 2906e52347bdSJani Nikula messages can reach various consoles while the rest 2907e52347bdSJani Nikula of the system is being put to sleep (ie, while 2908e52347bdSJani Nikula debugging driver suspend/resume hooks). This may 2909e52347bdSJani Nikula not work reliably with all consoles, but is known 2910e52347bdSJani Nikula to work with serial and VGA consoles. 2911e52347bdSJani Nikula To facilitate more flexible debugging, we also add 2912e52347bdSJani Nikula console_suspend, a printk module parameter to control 2913e52347bdSJani Nikula it. Users could use console_suspend (usually 2914e52347bdSJani Nikula /sys/module/printk/parameters/console_suspend) to 2915e52347bdSJani Nikula turn on/off it dynamically. 2916e52347bdSJani Nikula 2917c6c40533SKairui Song novmcoredd [KNL,KDUMP] 2918c6c40533SKairui Song Disable device dump. Device dump allows drivers to 2919c6c40533SKairui Song append dump data to vmcore so you can collect driver 2920c6c40533SKairui Song specified debug info. Drivers can append the data 2921c6c40533SKairui Song without any limit and this data is stored in memory, 2922c6c40533SKairui Song so this may cause significant memory stress. Disabling 2923c6c40533SKairui Song device dump can help save memory but the driver debug 2924c6c40533SKairui Song data will be no longer available. This parameter 2925c6c40533SKairui Song is only available when CONFIG_PROC_VMCORE_DEVICE_DUMP 2926c6c40533SKairui Song is set. 2927c6c40533SKairui Song 2928e52347bdSJani Nikula noaliencache [MM, NUMA, SLAB] Disables the allocation of alien 2929e52347bdSJani Nikula caches in the slab allocator. Saves per-node memory, 2930e52347bdSJani Nikula but will impact performance. 2931e52347bdSJani Nikula 2932e52347bdSJani Nikula noalign [KNL,ARM] 2933e52347bdSJani Nikula 2934686140a1SVasily Gorbik noaltinstr [S390] Disables alternative instructions patching 2935686140a1SVasily Gorbik (CPU alternatives feature). 2936686140a1SVasily Gorbik 2937e52347bdSJani Nikula noapic [SMP,APIC] Tells the kernel to not make use of any 2938e52347bdSJani Nikula IOAPICs that may be present in the system. 2939e52347bdSJani Nikula 2940e52347bdSJani Nikula noautogroup Disable scheduler automatic task group creation. 2941e52347bdSJani Nikula 2942e52347bdSJani Nikula nobats [PPC] Do not use BATs for mapping kernel lowmem 2943e52347bdSJani Nikula on "Classic" PPC cores. 2944e52347bdSJani Nikula 2945e52347bdSJani Nikula nocache [ARM] 2946e52347bdSJani Nikula 2947e52347bdSJani Nikula noclflush [BUGS=X86] Don't use the CLFLUSH instruction 2948e52347bdSJani Nikula 2949e52347bdSJani Nikula nodelayacct [KNL] Disable per-task delay accounting 2950e52347bdSJani Nikula 2951e52347bdSJani Nikula nodsp [SH] Disable hardware DSP at boot time. 2952e52347bdSJani Nikula 2953e52347bdSJani Nikula noefi Disable EFI runtime services support. 2954e52347bdSJani Nikula 2955e52347bdSJani Nikula noexec [IA-64] 2956e52347bdSJani Nikula 2957e52347bdSJani Nikula noexec [X86] 2958e52347bdSJani Nikula On X86-32 available only on PAE configured kernels. 2959e52347bdSJani Nikula noexec=on: enable non-executable mappings (default) 2960e52347bdSJani Nikula noexec=off: disable non-executable mappings 2961e52347bdSJani Nikula 2962de78a9c4SChristophe Leroy nosmap [X86,PPC] 2963e52347bdSJani Nikula Disable SMAP (Supervisor Mode Access Prevention) 2964e52347bdSJani Nikula even if it is supported by processor. 2965e52347bdSJani Nikula 29660fb1c25aSChristophe Leroy nosmep [X86,PPC] 2967e52347bdSJani Nikula Disable SMEP (Supervisor Mode Execution Prevention) 2968e52347bdSJani Nikula even if it is supported by processor. 2969e52347bdSJani Nikula 2970e52347bdSJani Nikula noexec32 [X86-64] 2971e52347bdSJani Nikula This affects only 32-bit executables. 2972e52347bdSJani Nikula noexec32=on: enable non-executable mappings (default) 2973e52347bdSJani Nikula read doesn't imply executable mappings 2974e52347bdSJani Nikula noexec32=off: disable non-executable mappings 2975e52347bdSJani Nikula read implies executable mappings 2976e52347bdSJani Nikula 2977e52347bdSJani Nikula nofpu [MIPS,SH] Disable hardware FPU at boot time. 2978e52347bdSJani Nikula 2979e52347bdSJani Nikula nofxsr [BUGS=X86-32] Disables x86 floating point extended 2980e52347bdSJani Nikula register save and restore. The kernel will only save 2981e52347bdSJani Nikula legacy floating-point registers on task switch. 2982e52347bdSJani Nikula 2983d909f910SNicholas Piggin nohugeiomap [KNL,x86,PPC] Disable kernel huge I/O mappings. 2984e52347bdSJani Nikula 2985e52347bdSJani Nikula nosmt [KNL,S390] Disable symmetric multithreading (SMT). 2986e52347bdSJani Nikula Equivalent to smt=1. 2987e52347bdSJani Nikula 298805736e4aSThomas Gleixner [KNL,x86] Disable symmetric multithreading (SMT). 2989506a66f3SThomas Gleixner nosmt=force: Force disable SMT, cannot be undone 2990506a66f3SThomas Gleixner via the sysfs control file. 299105736e4aSThomas Gleixner 2992a2059825SJosh Poimboeuf nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1 2993a2059825SJosh Poimboeuf (bounds check bypass). With this option data leaks are 2994a2059825SJosh Poimboeuf possible in the system. 299526cb1f36SDiana Craciun 2996e5ce5e72SJeremy Linton nospectre_v2 [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for 2997e5ce5e72SJeremy Linton the Spectre variant 2 (indirect branch prediction) 2998e5ce5e72SJeremy Linton vulnerability. System may allow data leaks with this 2999e5ce5e72SJeremy Linton option. 3000da285121SDavid Woodhouse 300124f7fc83SKonrad Rzeszutek Wilk nospec_store_bypass_disable 300224f7fc83SKonrad Rzeszutek Wilk [HW] Disable all mitigations for the Speculative Store Bypass vulnerability 300324f7fc83SKonrad Rzeszutek Wilk 3004e52347bdSJani Nikula noxsave [BUGS=X86] Disables x86 extended register state save 3005e52347bdSJani Nikula and restore using xsave. The kernel will fallback to 3006e52347bdSJani Nikula enabling legacy floating-point and sse state. 3007e52347bdSJani Nikula 3008e52347bdSJani Nikula noxsaveopt [X86] Disables xsaveopt used in saving x86 extended 3009e52347bdSJani Nikula register states. The kernel will fall back to use 3010e52347bdSJani Nikula xsave to save the states. By using this parameter, 3011e52347bdSJani Nikula performance of saving the states is degraded because 3012e52347bdSJani Nikula xsave doesn't support modified optimization while 3013e52347bdSJani Nikula xsaveopt supports it on xsaveopt enabled systems. 3014e52347bdSJani Nikula 3015e52347bdSJani Nikula noxsaves [X86] Disables xsaves and xrstors used in saving and 3016e52347bdSJani Nikula restoring x86 extended register state in compacted 3017e52347bdSJani Nikula form of xsave area. The kernel will fall back to use 3018e52347bdSJani Nikula xsaveopt and xrstor to save and restore the states 3019e52347bdSJani Nikula in standard form of xsave area. By using this 3020e52347bdSJani Nikula parameter, xsave area per process might occupy more 3021e52347bdSJani Nikula memory on xsaves enabled systems. 3022e52347bdSJani Nikula 3023e52347bdSJani Nikula nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or 3024e52347bdSJani Nikula wfi(ARM) instruction doesn't work correctly and not to 3025e52347bdSJani Nikula use it. This is also useful when using JTAG debugger. 3026e52347bdSJani Nikula 3027e52347bdSJani Nikula no_file_caps Tells the kernel not to honor file capabilities. The 3028e52347bdSJani Nikula only way then for a file to be executed with privilege 3029e52347bdSJani Nikula is to be setuid root or executed by root. 3030e52347bdSJani Nikula 3031e52347bdSJani Nikula nohalt [IA-64] Tells the kernel not to use the power saving 3032e52347bdSJani Nikula function PAL_HALT_LIGHT when idle. This increases 3033e52347bdSJani Nikula power-consumption. On the positive side, it reduces 3034e52347bdSJani Nikula interrupt wake-up latency, which may improve performance 3035e52347bdSJani Nikula in certain environments such as networked servers or 3036e52347bdSJani Nikula real-time systems. 3037e52347bdSJani Nikula 3038e52347bdSJani Nikula nohibernate [HIBERNATION] Disable hibernation and resume. 3039e52347bdSJani Nikula 3040e52347bdSJani Nikula nohz= [KNL] Boottime enable/disable dynamic ticks 3041e52347bdSJani Nikula Valid arguments: on, off 3042e52347bdSJani Nikula Default: on 3043e52347bdSJani Nikula 3044d94d1053SFrederic Weisbecker nohz_full= [KNL,BOOT,SMP,ISOL] 3045e52347bdSJani Nikula The argument is a cpu list, as described above. 3046e52347bdSJani Nikula In kernels built with CONFIG_NO_HZ_FULL=y, set 3047e52347bdSJani Nikula the specified list of CPUs whose tick will be stopped 3048e52347bdSJani Nikula whenever possible. The boot CPU will be forced outside 3049f99bcb2cSPaul E. McKenney the range to maintain the timekeeping. Any CPUs 3050f99bcb2cSPaul E. McKenney in this list will have their RCU callbacks offloaded, 3051f99bcb2cSPaul E. McKenney just as if they had also been called out in the 3052f99bcb2cSPaul E. McKenney rcu_nocbs= boot parameter. 3053e52347bdSJani Nikula 3054e52347bdSJani Nikula noiotrap [SH] Disables trapped I/O port accesses. 3055e52347bdSJani Nikula 3056e52347bdSJani Nikula noirqdebug [X86-32] Disables the code which attempts to detect and 3057e52347bdSJani Nikula disable unhandled interrupt sources. 3058e52347bdSJani Nikula 3059e52347bdSJani Nikula no_timer_check [X86,APIC] Disables the code which tests for 3060e52347bdSJani Nikula broken timer IRQ sources. 3061e52347bdSJani Nikula 3062e52347bdSJani Nikula noisapnp [ISAPNP] Disables ISA PnP code. 3063e52347bdSJani Nikula 3064e52347bdSJani Nikula noinitrd [RAM] Tells the kernel not to load any configured 3065e52347bdSJani Nikula initial RAM disk. 3066e52347bdSJani Nikula 3067e52347bdSJani Nikula nointremap [X86-64, Intel-IOMMU] Do not enable interrupt 3068e52347bdSJani Nikula remapping. 3069e52347bdSJani Nikula [Deprecated - use intremap=off] 3070e52347bdSJani Nikula 3071e52347bdSJani Nikula nointroute [IA-64] 3072e52347bdSJani Nikula 3073e52347bdSJani Nikula noinvpcid [X86] Disable the INVPCID cpu feature. 3074e52347bdSJani Nikula 3075e52347bdSJani Nikula nojitter [IA-64] Disables jitter checking for ITC timers. 3076e52347bdSJani Nikula 3077e52347bdSJani Nikula no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver 3078e52347bdSJani Nikula 3079e52347bdSJani Nikula no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page 3080e52347bdSJani Nikula fault handling. 3081e52347bdSJani Nikula 3082e7aa8c2eSLinus Torvalds no-vmw-sched-clock 3083e7aa8c2eSLinus Torvalds [X86,PV_OPS] Disable paravirtualized VMware scheduler 3084e7aa8c2eSLinus Torvalds clock and use the default one. 3085e7aa8c2eSLinus Torvalds 3086e52347bdSJani Nikula no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting. 3087e52347bdSJani Nikula steal time is computed, but won't influence scheduler 3088e52347bdSJani Nikula behaviour 3089e52347bdSJani Nikula 3090e52347bdSJani Nikula nolapic [X86-32,APIC] Do not enable or use the local APIC. 3091e52347bdSJani Nikula 3092e52347bdSJani Nikula nolapic_timer [X86-32,APIC] Do not use the local APIC timer. 3093e52347bdSJani Nikula 3094e52347bdSJani Nikula noltlbs [PPC] Do not use large page/tlb entries for kernel 3095e52347bdSJani Nikula lowmem mapping on PPC40x and PPC8xx 3096e52347bdSJani Nikula 3097e52347bdSJani Nikula nomca [IA-64] Disable machine check abort handling 3098e52347bdSJani Nikula 3099e52347bdSJani Nikula nomce [X86-32] Disable Machine Check Exception 3100e52347bdSJani Nikula 3101e52347bdSJani Nikula nomfgpt [X86-32] Disable Multi-Function General Purpose 3102e52347bdSJani Nikula Timer usage (for AMD Geode machines). 3103e52347bdSJani Nikula 3104e52347bdSJani Nikula nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to 3105e52347bdSJani Nikula shutdown the other cpus. Instead use the REBOOT_VECTOR 3106e52347bdSJani Nikula irq. 3107e52347bdSJani Nikula 3108e52347bdSJani Nikula nomodule Disable module load 3109e52347bdSJani Nikula 3110e52347bdSJani Nikula nopat [X86] Disable PAT (page attribute table extension of 3111e52347bdSJani Nikula pagetables) support. 3112e52347bdSJani Nikula 31130790c9aaSAndy Lutomirski nopcid [X86-64] Disable the PCID cpu feature. 31140790c9aaSAndy Lutomirski 3115e52347bdSJani Nikula norandmaps Don't use address space randomization. Equivalent to 3116e52347bdSJani Nikula echo 0 > /proc/sys/kernel/randomize_va_space 3117e52347bdSJani Nikula 3118e52347bdSJani Nikula noreplace-smp [X86-32,SMP] Don't replace SMP instructions 3119e52347bdSJani Nikula with UP alternatives 3120e52347bdSJani Nikula 3121e52347bdSJani Nikula nordrand [X86] Disable kernel use of the RDRAND and 3122e52347bdSJani Nikula RDSEED instructions even if they are supported 3123e52347bdSJani Nikula by the processor. RDRAND and RDSEED are still 3124e52347bdSJani Nikula available to user space applications. 3125e52347bdSJani Nikula 3126e52347bdSJani Nikula noresume [SWSUSP] Disables resume and restores original swap 3127e52347bdSJani Nikula space. 3128e52347bdSJani Nikula 3129e52347bdSJani Nikula no-scroll [VGA] Disables scrollback. 3130e52347bdSJani Nikula This is required for the Braillex ib80-piezo Braille 3131e52347bdSJani Nikula reader made by F.H. Papenmeier (Germany). 3132e52347bdSJani Nikula 3133e52347bdSJani Nikula nosbagart [IA-64] 3134e52347bdSJani Nikula 3135e52347bdSJani Nikula nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. 3136e52347bdSJani Nikula 3137e52347bdSJani Nikula nosmp [SMP] Tells an SMP kernel to act as a UP kernel, 3138e52347bdSJani Nikula and disable the IO APIC. legacy for "maxcpus=0". 3139e52347bdSJani Nikula 3140e52347bdSJani Nikula nosoftlockup [KNL] Disable the soft-lockup detector. 3141e52347bdSJani Nikula 3142e52347bdSJani Nikula nosync [HW,M68K] Disables sync negotiation for all devices. 3143e52347bdSJani Nikula 3144e52347bdSJani Nikula nowatchdog [KNL] Disable both lockup detectors, i.e. 3145e52347bdSJani Nikula soft-lockup and NMI watchdog (hard-lockup). 3146e52347bdSJani Nikula 3147e52347bdSJani Nikula nowb [ARM] 3148e52347bdSJani Nikula 3149e52347bdSJani Nikula nox2apic [X86-64,APIC] Do not enable x2APIC mode. 3150e52347bdSJani Nikula 3151e52347bdSJani Nikula cpu0_hotplug [X86] Turn on CPU0 hotplug feature when 3152e52347bdSJani Nikula CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. 3153e52347bdSJani Nikula Some features depend on CPU0. Known dependencies are: 3154e52347bdSJani Nikula 1. Resume from suspend/hibernate depends on CPU0. 3155e52347bdSJani Nikula Suspend/hibernate will fail if CPU0 is offline and you 3156e52347bdSJani Nikula need to online CPU0 before suspend/hibernate. 3157e52347bdSJani Nikula 2. PIC interrupts also depend on CPU0. CPU0 can't be 3158e52347bdSJani Nikula removed if a PIC interrupt is detected. 3159e52347bdSJani Nikula It's said poweroff/reboot may depend on CPU0 on some 3160e52347bdSJani Nikula machines although I haven't seen such issues so far 3161e52347bdSJani Nikula after CPU0 is offline on a few tested machines. 3162e52347bdSJani Nikula If the dependencies are under your control, you can 3163e52347bdSJani Nikula turn on cpu0_hotplug. 3164e52347bdSJani Nikula 316535b55ef2SNoam Camus nps_mtm_hs_ctr= [KNL,ARC] 316635b55ef2SNoam Camus This parameter sets the maximum duration, in 316735b55ef2SNoam Camus cycles, each HW thread of the CTOP can run 316835b55ef2SNoam Camus without interruptions, before HW switches it. 316935b55ef2SNoam Camus The actual maximum duration is 16 times this 317035b55ef2SNoam Camus parameter's value. 317135b55ef2SNoam Camus Format: integer between 1 and 255 317235b55ef2SNoam Camus Default: 255 317335b55ef2SNoam Camus 3174e52347bdSJani Nikula nptcg= [IA-64] Override max number of concurrent global TLB 3175e52347bdSJani Nikula purges which is reported from either PAL_VM_SUMMARY or 3176e52347bdSJani Nikula SAL PALO. 3177e52347bdSJani Nikula 3178e52347bdSJani Nikula nr_cpus= [SMP] Maximum number of processors that an SMP kernel 3179e52347bdSJani Nikula could support. nr_cpus=n : n >= 1 limits the kernel to 3180e52347bdSJani Nikula support 'n' processors. It could be larger than the 3181e52347bdSJani Nikula number of already plugged CPU during bootup, later in 3182e52347bdSJani Nikula runtime you can physically add extra cpu until it reaches 3183e52347bdSJani Nikula n. So during boot up some boot time memory for per-cpu 3184e52347bdSJani Nikula variables need be pre-allocated for later physical cpu 3185e52347bdSJani Nikula hot plugging. 3186e52347bdSJani Nikula 3187e52347bdSJani Nikula nr_uarts= [SERIAL] maximum number of UARTs to be registered. 3188e52347bdSJani Nikula 3189e52347bdSJani Nikula numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing. 3190e52347bdSJani Nikula Allowed values are enable and disable 3191e52347bdSJani Nikula 3192e52347bdSJani Nikula numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. 3193c9bff3eeSMichal Hocko 'node', 'default' can be specified 3194e52347bdSJani Nikula This can be set from sysctl after boot. 319557043247SMauro Carvalho Chehab See Documentation/admin-guide/sysctl/vm.rst for details. 3196e52347bdSJani Nikula 3197e52347bdSJani Nikula ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. 3198e52347bdSJani Nikula See Documentation/debugging-via-ohci1394.txt for more 3199e52347bdSJani Nikula info. 3200e52347bdSJani Nikula 3201e52347bdSJani Nikula olpc_ec_timeout= [OLPC] ms delay when issuing EC commands 3202e52347bdSJani Nikula Rather than timing out after 20 ms if an EC 3203e52347bdSJani Nikula command is not properly ACKed, override the length 3204e52347bdSJani Nikula of the timeout. We have interrupts disabled while 3205e52347bdSJani Nikula waiting for the ACK, so if this is set too high 3206e52347bdSJani Nikula interrupts *may* be lost! 3207e52347bdSJani Nikula 3208e52347bdSJani Nikula omap_mux= [OMAP] Override bootloader pin multiplexing. 3209e52347bdSJani Nikula Format: <mux_mode0.mode_name=value>... 3210e52347bdSJani Nikula For example, to override I2C bus2: 3211e52347bdSJani Nikula omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 3212e52347bdSJani Nikula 3213e52347bdSJani Nikula oprofile.timer= [HW] 3214e52347bdSJani Nikula Use timer interrupt instead of performance counters 3215e52347bdSJani Nikula 3216e52347bdSJani Nikula oprofile.cpu_type= Force an oprofile cpu type 3217e52347bdSJani Nikula This might be useful if you have an older oprofile 3218e52347bdSJani Nikula userland or if you want common events. 3219e52347bdSJani Nikula Format: { arch_perfmon } 3220e52347bdSJani Nikula arch_perfmon: [X86] Force use of architectural 3221e52347bdSJani Nikula perfmon on Intel CPUs instead of the 3222e52347bdSJani Nikula CPU specific event set. 3223e52347bdSJani Nikula timer: [X86] Force use of architectural NMI 3224e52347bdSJani Nikula timer mode (see also oprofile.timer 3225e52347bdSJani Nikula for generic hr timer mode) 3226e52347bdSJani Nikula 3227e52347bdSJani Nikula oops=panic Always panic on oopses. Default is to just kill the 3228e52347bdSJani Nikula process, but there is a small probability of 3229e52347bdSJani Nikula deadlocking the machine. 3230e52347bdSJani Nikula This will also cause panics on machine check exceptions. 3231e52347bdSJani Nikula Useful together with panic=30 to trigger a reboot. 3232e52347bdSJani Nikula 3233e900a918SDan Williams page_alloc.shuffle= 3234e900a918SDan Williams [KNL] Boolean flag to control whether the page allocator 3235e900a918SDan Williams should randomize its free lists. The randomization may 3236e900a918SDan Williams be automatically enabled if the kernel detects it is 3237e900a918SDan Williams running on a platform with a direct-mapped memory-side 3238e900a918SDan Williams cache, and this parameter can be used to 3239e900a918SDan Williams override/disable that behavior. The state of the flag 3240e900a918SDan Williams can be read from sysfs at: 3241e900a918SDan Williams /sys/module/page_alloc/parameters/shuffle. 3242e900a918SDan Williams 3243e52347bdSJani Nikula page_owner= [KNL] Boot-time page_owner enabling option. 3244e52347bdSJani Nikula Storage of the information about who allocated 3245e52347bdSJani Nikula each page is disabled in default. With this switch, 3246e52347bdSJani Nikula we can turn it on. 3247e52347bdSJani Nikula on: enable the feature 3248e52347bdSJani Nikula 3249e52347bdSJani Nikula page_poison= [KNL] Boot-time parameter changing the state of 32508c9a134cSKees Cook poisoning on the buddy allocator, available with 32518c9a134cSKees Cook CONFIG_PAGE_POISONING=y. 32528c9a134cSKees Cook off: turn off poisoning (default) 3253e52347bdSJani Nikula on: turn on poisoning 3254e52347bdSJani Nikula 3255e52347bdSJani Nikula panic= [KNL] Kernel behaviour on panic: delay <timeout> 3256e52347bdSJani Nikula timeout > 0: seconds before rebooting 3257e52347bdSJani Nikula timeout = 0: wait forever 3258e52347bdSJani Nikula timeout < 0: reboot immediately 3259e52347bdSJani Nikula Format: <timeout> 3260e52347bdSJani Nikula 3261d999bd93SFeng Tang panic_print= Bitmask for printing system info when panic happens. 3262d999bd93SFeng Tang User can chose combination of the following bits: 3263d999bd93SFeng Tang bit 0: print all tasks info 3264d999bd93SFeng Tang bit 1: print system memory info 3265d999bd93SFeng Tang bit 2: print timer info 3266d999bd93SFeng Tang bit 3: print locks info if CONFIG_LOCKDEP is on 3267d999bd93SFeng Tang bit 4: print ftrace buffer 3268de6da1e8SFeng Tang bit 5: print all printk messages in buffer 3269d999bd93SFeng Tang 3270e52347bdSJani Nikula panic_on_warn panic() instead of WARN(). Useful to cause kdump 3271e52347bdSJani Nikula on a WARN(). 3272e52347bdSJani Nikula 3273e52347bdSJani Nikula crash_kexec_post_notifiers 3274e52347bdSJani Nikula Run kdump after running panic-notifiers and dumping 3275e52347bdSJani Nikula kmsg. This only for the users who doubt kdump always 3276e52347bdSJani Nikula succeeds in any situation. 3277e52347bdSJani Nikula Note that this also increases risks of kdump failure, 3278e52347bdSJani Nikula because some panic notifiers can make the crashed 3279e52347bdSJani Nikula kernel more unstable. 3280e52347bdSJani Nikula 3281e52347bdSJani Nikula parkbd.port= [HW] Parallel port number the keyboard adapter is 3282e52347bdSJani Nikula connected to, default is 0. 3283e52347bdSJani Nikula Format: <parport#> 3284e52347bdSJani Nikula parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, 3285e52347bdSJani Nikula 0 for XT, 1 for AT (default is AT). 3286e52347bdSJani Nikula Format: <mode> 3287e52347bdSJani Nikula 3288e52347bdSJani Nikula parport= [HW,PPT] Specify parallel ports. 0 disables. 3289e52347bdSJani Nikula Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } 3290e52347bdSJani Nikula Use 'auto' to force the driver to use any 3291e52347bdSJani Nikula IRQ/DMA settings detected (the default is to 3292e52347bdSJani Nikula ignore detected IRQ/DMA settings because of 3293e52347bdSJani Nikula possible conflicts). You can specify the base 3294e52347bdSJani Nikula address, IRQ, and DMA settings; IRQ and DMA 3295e52347bdSJani Nikula should be numbers, or 'auto' (for using detected 3296e52347bdSJani Nikula settings on that particular port), or 'nofifo' 3297e52347bdSJani Nikula (to avoid using a FIFO even if it is detected). 3298e52347bdSJani Nikula Parallel ports are assigned in the order they 3299e52347bdSJani Nikula are specified on the command line, starting 3300e52347bdSJani Nikula with parport0. 3301e52347bdSJani Nikula 3302e52347bdSJani Nikula parport_init_mode= [HW,PPT] 3303e52347bdSJani Nikula Configure VIA parallel port to operate in 3304e52347bdSJani Nikula a specific mode. This is necessary on Pegasos 3305e52347bdSJani Nikula computer where firmware has no options for setting 3306e52347bdSJani Nikula up parallel port mode and sets it to spp. 3307e52347bdSJani Nikula Currently this function knows 686a and 8231 chips. 3308e52347bdSJani Nikula Format: [spp|ps2|epp|ecp|ecpepp] 3309e52347bdSJani Nikula 3310e52347bdSJani Nikula pause_on_oops= 3311e52347bdSJani Nikula Halt all CPUs after the first oops has been printed for 3312e52347bdSJani Nikula the specified number of seconds. This is to be used if 3313e52347bdSJani Nikula your oopses keep scrolling off the screen. 3314e52347bdSJani Nikula 3315e52347bdSJani Nikula pcbit= [HW,ISDN] 3316e52347bdSJani Nikula 3317e52347bdSJani Nikula pcd. [PARIDE] 3318e52347bdSJani Nikula See header of drivers/block/paride/pcd.c. 3319e7751617SMauro Carvalho Chehab See also Documentation/admin-guide/blockdev/paride.rst. 3320e52347bdSJani Nikula 332107d8d7e5SLogan Gunthorpe pci=option[,option...] [PCI] various PCI subsystem options. 332207d8d7e5SLogan Gunthorpe 332307d8d7e5SLogan Gunthorpe Some options herein operate on a specific device 332407d8d7e5SLogan Gunthorpe or a set of devices (<pci_dev>). These are 332507d8d7e5SLogan Gunthorpe specified in one of the following formats: 332607d8d7e5SLogan Gunthorpe 332745db3370SLogan Gunthorpe [<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]* 332807d8d7e5SLogan Gunthorpe pci:<vendor>:<device>[:<subvendor>:<subdevice>] 332907d8d7e5SLogan Gunthorpe 333007d8d7e5SLogan Gunthorpe Note: the first format specifies a PCI 333107d8d7e5SLogan Gunthorpe bus/device/function address which may change 333207d8d7e5SLogan Gunthorpe if new hardware is inserted, if motherboard 333307d8d7e5SLogan Gunthorpe firmware changes, or due to changes caused 333407d8d7e5SLogan Gunthorpe by other kernel parameters. If the 333507d8d7e5SLogan Gunthorpe domain is left unspecified, it is 333645db3370SLogan Gunthorpe taken to be zero. Optionally, a path 333745db3370SLogan Gunthorpe to a device through multiple device/function 333845db3370SLogan Gunthorpe addresses can be specified after the base 333945db3370SLogan Gunthorpe address (this is more robust against 334045db3370SLogan Gunthorpe renumbering issues). The second format 334107d8d7e5SLogan Gunthorpe selects devices using IDs from the 334207d8d7e5SLogan Gunthorpe configuration space which may match multiple 334307d8d7e5SLogan Gunthorpe devices in the system. 334407d8d7e5SLogan Gunthorpe 334511eb0e0eSSinan Kaya earlydump dump PCI config space before the kernel 3346e52347bdSJani Nikula changes anything 3347e52347bdSJani Nikula off [X86] don't probe for the PCI bus 3348e52347bdSJani Nikula bios [X86-32] force use of PCI BIOS, don't access 3349e52347bdSJani Nikula the hardware directly. Use this if your machine 3350e52347bdSJani Nikula has a non-standard PCI host bridge. 3351e52347bdSJani Nikula nobios [X86-32] disallow use of PCI BIOS, only direct 3352e52347bdSJani Nikula hardware access methods are allowed. Use this 3353e52347bdSJani Nikula if you experience crashes upon bootup and you 3354e52347bdSJani Nikula suspect they are caused by the BIOS. 3355e52347bdSJani Nikula conf1 [X86] Force use of PCI Configuration Access 3356e52347bdSJani Nikula Mechanism 1 (config address in IO port 0xCF8, 3357e52347bdSJani Nikula data in IO port 0xCFC, both 32-bit). 3358e52347bdSJani Nikula conf2 [X86] Force use of PCI Configuration Access 3359e52347bdSJani Nikula Mechanism 2 (IO port 0xCF8 is an 8-bit port for 3360e52347bdSJani Nikula the function, IO port 0xCFA, also 8-bit, sets 3361e52347bdSJani Nikula bus number. The config space is then accessed 3362e52347bdSJani Nikula through ports 0xC000-0xCFFF). 3363e52347bdSJani Nikula See http://wiki.osdev.org/PCI for more info 3364e52347bdSJani Nikula on the configuration access mechanisms. 3365e52347bdSJani Nikula noaer [PCIE] If the PCIEAER kernel config parameter is 3366e52347bdSJani Nikula enabled, this kernel boot option can be used to 3367e52347bdSJani Nikula disable the use of PCIE advanced error reporting. 3368e52347bdSJani Nikula nodomains [PCI] Disable support for multiple PCI 3369e52347bdSJani Nikula root domains (aka PCI segments, in ACPI-speak). 3370e52347bdSJani Nikula nommconf [X86] Disable use of MMCONFIG for PCI 3371e52347bdSJani Nikula Configuration 3372e52347bdSJani Nikula check_enable_amd_mmconf [X86] check for and enable 3373e52347bdSJani Nikula properly configured MMIO access to PCI 3374e52347bdSJani Nikula config space on AMD family 10h CPU 3375e52347bdSJani Nikula nomsi [MSI] If the PCI_MSI kernel config parameter is 3376e52347bdSJani Nikula enabled, this kernel boot option can be used to 3377e52347bdSJani Nikula disable the use of MSI interrupts system-wide. 3378e52347bdSJani Nikula noioapicquirk [APIC] Disable all boot interrupt quirks. 3379e52347bdSJani Nikula Safety option to keep boot IRQs enabled. This 3380e52347bdSJani Nikula should never be necessary. 3381e52347bdSJani Nikula ioapicreroute [APIC] Enable rerouting of boot IRQs to the 3382e52347bdSJani Nikula primary IO-APIC for bridges that cannot disable 3383e52347bdSJani Nikula boot IRQs. This fixes a source of spurious IRQs 3384e52347bdSJani Nikula when the system masks IRQs. 3385e52347bdSJani Nikula noioapicreroute [APIC] Disable workaround that uses the 3386e52347bdSJani Nikula boot IRQ equivalent of an IRQ that connects to 3387e52347bdSJani Nikula a chipset where boot IRQs cannot be disabled. 3388e52347bdSJani Nikula The opposite of ioapicreroute. 3389e52347bdSJani Nikula biosirq [X86-32] Use PCI BIOS calls to get the interrupt 3390e52347bdSJani Nikula routing table. These calls are known to be buggy 3391e52347bdSJani Nikula on several machines and they hang the machine 3392e52347bdSJani Nikula when used, but on other computers it's the only 3393e52347bdSJani Nikula way to get the interrupt routing table. Try 3394e52347bdSJani Nikula this option if the kernel is unable to allocate 3395e52347bdSJani Nikula IRQs or discover secondary PCI buses on your 3396e52347bdSJani Nikula motherboard. 3397e52347bdSJani Nikula rom [X86] Assign address space to expansion ROMs. 3398e52347bdSJani Nikula Use with caution as certain devices share 3399e52347bdSJani Nikula address decoders between ROMs and other 3400e52347bdSJani Nikula resources. 3401e52347bdSJani Nikula norom [X86] Do not assign address space to 3402e52347bdSJani Nikula expansion ROMs that do not already have 3403e52347bdSJani Nikula BIOS assigned address ranges. 3404e52347bdSJani Nikula nobar [X86] Do not assign address space to the 3405e52347bdSJani Nikula BARs that weren't assigned by the BIOS. 3406e52347bdSJani Nikula irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be 3407e52347bdSJani Nikula assigned automatically to PCI devices. You can 3408e52347bdSJani Nikula make the kernel exclude IRQs of your ISA cards 3409e52347bdSJani Nikula this way. 3410e52347bdSJani Nikula pirqaddr=0xAAAAA [X86] Specify the physical address 3411e52347bdSJani Nikula of the PIRQ table (normally generated 3412e52347bdSJani Nikula by the BIOS) if it is outside the 3413e52347bdSJani Nikula F0000h-100000h range. 3414e52347bdSJani Nikula lastbus=N [X86] Scan all buses thru bus #N. Can be 3415e52347bdSJani Nikula useful if the kernel is unable to find your 3416e52347bdSJani Nikula secondary buses and you want to tell it 3417e52347bdSJani Nikula explicitly which ones they are. 3418e52347bdSJani Nikula assign-busses [X86] Always assign all PCI bus 3419e52347bdSJani Nikula numbers ourselves, overriding 3420e52347bdSJani Nikula whatever the firmware may have done. 3421e52347bdSJani Nikula usepirqmask [X86] Honor the possible IRQ mask stored 3422e52347bdSJani Nikula in the BIOS $PIR table. This is needed on 3423e52347bdSJani Nikula some systems with broken BIOSes, notably 3424e52347bdSJani Nikula some HP Pavilion N5400 and Omnibook XE3 3425e52347bdSJani Nikula notebooks. This will have no effect if ACPI 3426e52347bdSJani Nikula IRQ routing is enabled. 3427e52347bdSJani Nikula noacpi [X86] Do not use ACPI for IRQ routing 3428e52347bdSJani Nikula or for PCI scanning. 3429e52347bdSJani Nikula use_crs [X86] Use PCI host bridge window information 3430e52347bdSJani Nikula from ACPI. On BIOSes from 2008 or later, this 3431e52347bdSJani Nikula is enabled by default. If you need to use this, 3432e52347bdSJani Nikula please report a bug. 3433e52347bdSJani Nikula nocrs [X86] Ignore PCI host bridge windows from ACPI. 3434e52347bdSJani Nikula If you need to use this, please report a bug. 3435e52347bdSJani Nikula routeirq Do IRQ routing for all PCI devices. 3436e52347bdSJani Nikula This is normally done in pci_enable_device(), 3437e52347bdSJani Nikula so this option is a temporary workaround 3438e52347bdSJani Nikula for broken drivers that don't call it. 3439e52347bdSJani Nikula skip_isa_align [X86] do not align io start addr, so can 3440e52347bdSJani Nikula handle more pci cards 3441e52347bdSJani Nikula noearly [X86] Don't do any early type 1 scanning. 3442e52347bdSJani Nikula This might help on some broken boards which 3443e52347bdSJani Nikula machine check when some devices' config space 3444e52347bdSJani Nikula is read. But various workarounds are disabled 3445e52347bdSJani Nikula and some IOMMU drivers will not work. 3446e52347bdSJani Nikula bfsort Sort PCI devices into breadth-first order. 3447e52347bdSJani Nikula This sorting is done to get a device 3448e52347bdSJani Nikula order compatible with older (<= 2.4) kernels. 3449e52347bdSJani Nikula nobfsort Don't sort PCI devices into breadth-first order. 3450e52347bdSJani Nikula pcie_bus_tune_off Disable PCIe MPS (Max Payload Size) 3451e52347bdSJani Nikula tuning and use the BIOS-configured MPS defaults. 3452e52347bdSJani Nikula pcie_bus_safe Set every device's MPS to the largest value 3453e52347bdSJani Nikula supported by all devices below the root complex. 3454e52347bdSJani Nikula pcie_bus_perf Set device MPS to the largest allowable MPS 3455e52347bdSJani Nikula based on its parent bus. Also set MRRS (Max 3456e52347bdSJani Nikula Read Request Size) to the largest supported 3457e52347bdSJani Nikula value (no larger than the MPS that the device 3458e52347bdSJani Nikula or bus can support) for best performance. 3459e52347bdSJani Nikula pcie_bus_peer2peer Set every device's MPS to 128B, which 3460e52347bdSJani Nikula every device is guaranteed to support. This 3461e52347bdSJani Nikula configuration allows peer-to-peer DMA between 3462e52347bdSJani Nikula any pair of devices, possibly at the cost of 3463e52347bdSJani Nikula reduced performance. This also guarantees 3464e52347bdSJani Nikula that hot-added devices will work. 3465e52347bdSJani Nikula cbiosize=nn[KMG] The fixed amount of bus space which is 3466e52347bdSJani Nikula reserved for the CardBus bridge's IO window. 3467e52347bdSJani Nikula The default value is 256 bytes. 3468e52347bdSJani Nikula cbmemsize=nn[KMG] The fixed amount of bus space which is 3469e52347bdSJani Nikula reserved for the CardBus bridge's memory 3470e52347bdSJani Nikula window. The default value is 64 megabytes. 3471e52347bdSJani Nikula resource_alignment= 3472e52347bdSJani Nikula Format: 347307d8d7e5SLogan Gunthorpe [<order of align>@]<pci_dev>[; ...] 3474e52347bdSJani Nikula Specifies alignment and device to reassign 347507d8d7e5SLogan Gunthorpe aligned memory resources. How to 347607d8d7e5SLogan Gunthorpe specify the device is described above. 3477e52347bdSJani Nikula If <order of align> is not specified, 3478e52347bdSJani Nikula PAGE_SIZE is used as alignment. 34793b1b1ce3SAlexey Kardashevskiy A PCI-PCI bridge can be specified if resource 3480e52347bdSJani Nikula windows need to be expanded. 3481e52347bdSJani Nikula To specify the alignment for several 3482e52347bdSJani Nikula instances of a device, the PCI vendor, 3483e52347bdSJani Nikula device, subvendor, and subdevice may be 34843b1b1ce3SAlexey Kardashevskiy specified, e.g., 12@pci:8086:9c22:103c:198f 34853b1b1ce3SAlexey Kardashevskiy for 4096-byte alignment. 3486e52347bdSJani Nikula ecrc= Enable/disable PCIe ECRC (transaction layer 3487e52347bdSJani Nikula end-to-end CRC checking). 3488e52347bdSJani Nikula bios: Use BIOS/firmware settings. This is the 3489e52347bdSJani Nikula the default. 3490e52347bdSJani Nikula off: Turn ECRC off 3491e52347bdSJani Nikula on: Turn ECRC on. 3492e52347bdSJani Nikula hpiosize=nn[KMG] The fixed amount of bus space which is 3493e52347bdSJani Nikula reserved for hotplug bridge's IO window. 3494e52347bdSJani Nikula Default size is 256 bytes. 3495e52347bdSJani Nikula hpmemsize=nn[KMG] The fixed amount of bus space which is 3496e52347bdSJani Nikula reserved for hotplug bridge's memory window. 3497e52347bdSJani Nikula Default size is 2 megabytes. 3498e52347bdSJani Nikula hpbussize=nn The minimum amount of additional bus numbers 3499e52347bdSJani Nikula reserved for buses below a hotplug bridge. 3500e52347bdSJani Nikula Default is 1. 3501e52347bdSJani Nikula realloc= Enable/disable reallocating PCI bridge resources 3502e52347bdSJani Nikula if allocations done by BIOS are too small to 3503e52347bdSJani Nikula accommodate resources required by all child 3504e52347bdSJani Nikula devices. 3505e52347bdSJani Nikula off: Turn realloc off 3506e52347bdSJani Nikula on: Turn realloc on 3507e52347bdSJani Nikula realloc same as realloc=on 3508e52347bdSJani Nikula noari do not use PCIe ARI. 3509cef74409SGil Kupfer noats [PCIE, Intel-IOMMU, AMD-IOMMU] 3510cef74409SGil Kupfer do not use PCIe ATS (and IOMMU device IOTLB). 3511e52347bdSJani Nikula pcie_scan_all Scan all possible PCIe devices. Otherwise we 3512e52347bdSJani Nikula only look for one device below a PCIe downstream 3513e52347bdSJani Nikula port. 3514f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= big_root_window Try to add a big 64bit memory window to the PCIe 3515f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= root complex on AMD CPUs. Some GFX hardware 3516f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= can resize a BAR to allow access to all VRAM. 3517f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= Adding the window is slightly risky (it may 3518f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= conflict with unreported devices), so this 3519f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= taints the kernel. 3520aaca43fdSLogan Gunthorpe disable_acs_redir=<pci_dev>[; ...] 3521aaca43fdSLogan Gunthorpe Specify one or more PCI devices (in the format 3522aaca43fdSLogan Gunthorpe specified above) separated by semicolons. 3523aaca43fdSLogan Gunthorpe Each device specified will have the PCI ACS 3524aaca43fdSLogan Gunthorpe redirect capabilities forced off which will 3525aaca43fdSLogan Gunthorpe allow P2P traffic between devices through 3526aaca43fdSLogan Gunthorpe bridges without forcing it upstream. Note: 3527aaca43fdSLogan Gunthorpe this removes isolation between devices and 3528aaca43fdSLogan Gunthorpe may put more devices in an IOMMU group. 3529fbfe07d4SSebastian Ott force_floating [S390] Force usage of floating interrupts. 353056271303SSebastian Ott nomio [S390] Do not use MIO instructions. 3531e52347bdSJani Nikula 3532e52347bdSJani Nikula pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power 3533e52347bdSJani Nikula Management. 3534e52347bdSJani Nikula off Disable ASPM. 3535e52347bdSJani Nikula force Enable ASPM even on devices that claim not to support it. 3536e52347bdSJani Nikula WARNING: Forcing ASPM on may cause system lockups. 3537e52347bdSJani Nikula 35384c0fd764SBjorn Helgaas pcie_ports= [PCIE] PCIe port services handling: 35394c0fd764SBjorn Helgaas native Use native PCIe services (PME, AER, DPC, PCIe hotplug) 35404c0fd764SBjorn Helgaas even if the platform doesn't give the OS permission to 35414c0fd764SBjorn Helgaas use them. This may cause conflicts if the platform 35424c0fd764SBjorn Helgaas also tries to use these services. 35434c0fd764SBjorn Helgaas compat Disable native PCIe services (PME, AER, DPC, PCIe 35444c0fd764SBjorn Helgaas hotplug). 3545e52347bdSJani Nikula 3546e52347bdSJani Nikula pcie_port_pm= [PCIE] PCIe port power management handling: 3547e52347bdSJani Nikula off Disable power management of all PCIe ports 3548e52347bdSJani Nikula force Forcibly enable power management of all PCIe ports 3549e52347bdSJani Nikula 3550e52347bdSJani Nikula pcie_pme= [PCIE,PM] Native PCIe PME signaling options: 3551e52347bdSJani Nikula nomsi Do not use MSI for native PCIe PME signaling (this makes 3552e52347bdSJani Nikula all PCIe root ports use INTx for all services). 3553e52347bdSJani Nikula 3554e52347bdSJani Nikula pcmv= [HW,PCMCIA] BadgePAD 4 3555e52347bdSJani Nikula 3556e52347bdSJani Nikula pd_ignore_unused 3557e52347bdSJani Nikula [PM] 3558e52347bdSJani Nikula Keep all power-domains already enabled by bootloader on, 3559e52347bdSJani Nikula even if no driver has claimed them. This is useful 3560e52347bdSJani Nikula for debug and development, but should not be 3561e52347bdSJani Nikula needed on a platform with proper driver support. 3562e52347bdSJani Nikula 3563e52347bdSJani Nikula pd. [PARIDE] 3564e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/paride.rst. 3565e52347bdSJani Nikula 3566e52347bdSJani Nikula pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at 3567e52347bdSJani Nikula boot time. 3568e52347bdSJani Nikula Format: { 0 | 1 } 3569e52347bdSJani Nikula See arch/parisc/kernel/pdc_chassis.c 3570e52347bdSJani Nikula 3571e52347bdSJani Nikula percpu_alloc= Select which percpu first chunk allocator to use. 3572e52347bdSJani Nikula Currently supported values are "embed" and "page". 3573e52347bdSJani Nikula Archs may support subset or none of the selections. 3574e52347bdSJani Nikula See comments in mm/percpu.c for details on each 3575e52347bdSJani Nikula allocator. This parameter is primarily for debugging 3576e52347bdSJani Nikula and performance comparison. 3577e52347bdSJani Nikula 3578e52347bdSJani Nikula pf. [PARIDE] 3579e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/paride.rst. 3580e52347bdSJani Nikula 3581e52347bdSJani Nikula pg. [PARIDE] 3582e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/paride.rst. 3583e52347bdSJani Nikula 3584e52347bdSJani Nikula pirq= [SMP,APIC] Manual mp-table setup 3585cb1aaebeSMauro Carvalho Chehab See Documentation/x86/i386/IO-APIC.rst. 3586e52347bdSJani Nikula 3587e52347bdSJani Nikula plip= [PPT,NET] Parallel port network link 3588e52347bdSJani Nikula Format: { parport<nr> | timid | 0 } 35893ba9b1b8STom Saeger See also Documentation/admin-guide/parport.rst. 3590e52347bdSJani Nikula 3591e52347bdSJani Nikula pmtmr= [X86] Manual setup of pmtmr I/O Port. 3592e52347bdSJani Nikula Override pmtimer IOPort with a hex value. 3593e52347bdSJani Nikula e.g. pmtmr=0x508 3594e52347bdSJani Nikula 3595e52347bdSJani Nikula pnp.debug=1 [PNP] 3596e52347bdSJani Nikula Enable PNP debug messages (depends on the 3597e52347bdSJani Nikula CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time 3598e52347bdSJani Nikula via /sys/module/pnp/parameters/debug. We always show 3599e52347bdSJani Nikula current resource usage; turning this on also shows 3600e52347bdSJani Nikula possible settings and some assignment information. 3601e52347bdSJani Nikula 3602e52347bdSJani Nikula pnpacpi= [ACPI] 3603e52347bdSJani Nikula { off } 3604e52347bdSJani Nikula 3605e52347bdSJani Nikula pnpbios= [ISAPNP] 3606e52347bdSJani Nikula { on | off | curr | res | no-curr | no-res } 3607e52347bdSJani Nikula 3608e52347bdSJani Nikula pnp_reserve_irq= 3609e52347bdSJani Nikula [ISAPNP] Exclude IRQs for the autoconfiguration 3610e52347bdSJani Nikula 3611e52347bdSJani Nikula pnp_reserve_dma= 3612e52347bdSJani Nikula [ISAPNP] Exclude DMAs for the autoconfiguration 3613e52347bdSJani Nikula 3614e52347bdSJani Nikula pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration 3615e52347bdSJani Nikula Ranges are in pairs (I/O port base and size). 3616e52347bdSJani Nikula 3617e52347bdSJani Nikula pnp_reserve_mem= 3618e52347bdSJani Nikula [ISAPNP] Exclude memory regions for the 3619e52347bdSJani Nikula autoconfiguration. 3620e52347bdSJani Nikula Ranges are in pairs (memory base and size). 3621e52347bdSJani Nikula 3622e52347bdSJani Nikula ports= [IP_VS_FTP] IPVS ftp helper module 3623e52347bdSJani Nikula Default is 21. 3624e52347bdSJani Nikula Up to 8 (IP_VS_APP_MAX_PORTS) ports 3625e52347bdSJani Nikula may be specified. 3626e52347bdSJani Nikula Format: <port>,<port>.... 3627e52347bdSJani Nikula 3628c3cbd075SBalbir Singh powersave=off [PPC] This option disables power saving features. 3629c3cbd075SBalbir Singh It specifically disables cpuidle and sets the 3630c3cbd075SBalbir Singh platform machine description specific power_save 3631c3cbd075SBalbir Singh function to NULL. On Idle the CPU just reduces 3632c3cbd075SBalbir Singh execution priority. 3633c3cbd075SBalbir Singh 3634e52347bdSJani Nikula ppc_strict_facility_enable 3635e52347bdSJani Nikula [PPC] This option catches any kernel floating point, 3636e52347bdSJani Nikula Altivec, VSX and SPE outside of regions specifically 3637e52347bdSJani Nikula allowed (eg kernel_enable_fpu()/kernel_disable_fpu()). 3638e52347bdSJani Nikula There is some performance impact when enabling this. 3639e52347bdSJani Nikula 364007fd1761SCyril Bur ppc_tm= [PPC] 364107fd1761SCyril Bur Format: {"off"} 364207fd1761SCyril Bur Disable Hardware Transactional Memory 364307fd1761SCyril Bur 3644e52347bdSJani Nikula print-fatal-signals= 3645e52347bdSJani Nikula [KNL] debug: print fatal signals 3646e52347bdSJani Nikula 3647e52347bdSJani Nikula If enabled, warn about various signal handling 3648e52347bdSJani Nikula related application anomalies: too many signals, 3649e52347bdSJani Nikula too many POSIX.1 timers, fatal signals causing a 3650e52347bdSJani Nikula coredump - etc. 3651e52347bdSJani Nikula 3652e52347bdSJani Nikula If you hit the warning due to signal overflow, 3653e52347bdSJani Nikula you might want to try "ulimit -i unlimited". 3654e52347bdSJani Nikula 3655e52347bdSJani Nikula default: off. 3656e52347bdSJani Nikula 3657e52347bdSJani Nikula printk.always_kmsg_dump= 3658e52347bdSJani Nikula Trigger kmsg_dump for cases other than kernel oops or 3659e52347bdSJani Nikula panics 3660e52347bdSJani Nikula Format: <bool> (1/Y/y=enable, 0/N/n=disable) 3661e52347bdSJani Nikula default: disabled 3662e52347bdSJani Nikula 3663e52347bdSJani Nikula printk.devkmsg={on,off,ratelimit} 3664e52347bdSJani Nikula Control writing to /dev/kmsg. 3665e52347bdSJani Nikula on - unlimited logging to /dev/kmsg from userspace 3666e52347bdSJani Nikula off - logging to /dev/kmsg disabled 3667e52347bdSJani Nikula ratelimit - ratelimit the logging 3668e52347bdSJani Nikula Default: ratelimit 3669e52347bdSJani Nikula 3670e52347bdSJani Nikula printk.time= Show timing data prefixed to each printk message line 3671e52347bdSJani Nikula Format: <bool> (1/Y/y=enable, 0/N/n=disable) 3672e52347bdSJani Nikula 3673e52347bdSJani Nikula processor.max_cstate= [HW,ACPI] 3674e52347bdSJani Nikula Limit processor to maximum C-state 3675e52347bdSJani Nikula max_cstate=9 overrides any DMI blacklist limit. 3676e52347bdSJani Nikula 3677e52347bdSJani Nikula processor.nocst [HW,ACPI] 3678e52347bdSJani Nikula Ignore the _CST method to determine C-states, 3679e52347bdSJani Nikula instead using the legacy FADT method 3680e52347bdSJani Nikula 3681e52347bdSJani Nikula profile= [KNL] Enable kernel profiling via /proc/profile 3682e7e61fc0SRandy Dunlap Format: [<profiletype>,]<number> 3683e7e61fc0SRandy Dunlap Param: <profiletype>: "schedule", "sleep", or "kvm" 3684e7e61fc0SRandy Dunlap [defaults to kernel profiling] 3685e52347bdSJani Nikula Param: "schedule" - profile schedule points. 3686e52347bdSJani Nikula Param: "sleep" - profile D-state sleeping (millisecs). 3687e52347bdSJani Nikula Requires CONFIG_SCHEDSTATS 3688e52347bdSJani Nikula Param: "kvm" - profile VM exits. 3689e7e61fc0SRandy Dunlap Param: <number> - step/bucket size as a power of 2 for 3690e7e61fc0SRandy Dunlap statistical time based profiling. 3691e52347bdSJani Nikula 3692e52347bdSJani Nikula prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk 3693e52347bdSJani Nikula before loading. 3694e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/ramdisk.rst. 3695e52347bdSJani Nikula 3696e0c27447SJohannes Weiner psi= [KNL] Enable or disable pressure stall information 3697e0c27447SJohannes Weiner tracking. 3698e0c27447SJohannes Weiner Format: <bool> 3699e0c27447SJohannes Weiner 3700e52347bdSJani Nikula psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to 3701e52347bdSJani Nikula probe for; one of (bare|imps|exps|lifebook|any). 3702e52347bdSJani Nikula psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports 3703e52347bdSJani Nikula per second. 3704e52347bdSJani Nikula psmouse.resetafter= [HW,MOUSE] 3705e52347bdSJani Nikula Try to reset the device after so many bad packets 3706e52347bdSJani Nikula (0 = never). 3707e52347bdSJani Nikula psmouse.resolution= 3708e52347bdSJani Nikula [HW,MOUSE] Set desired mouse resolution, in dpi. 3709e52347bdSJani Nikula psmouse.smartscroll= 3710e52347bdSJani Nikula [HW,MOUSE] Controls Logitech smartscroll autorepeat. 3711e52347bdSJani Nikula 0 = disabled, 1 = enabled (default). 3712e52347bdSJani Nikula 3713e52347bdSJani Nikula pstore.backend= Specify the name of the pstore backend to use 3714e52347bdSJani Nikula 3715e52347bdSJani Nikula pt. [PARIDE] 3716e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/paride.rst. 3717e52347bdSJani Nikula 371801c9b17bSDave Hansen pti= [X86_64] Control Page Table Isolation of user and 371901c9b17bSDave Hansen kernel address spaces. Disabling this feature 372001c9b17bSDave Hansen removes hardening, but improves performance of 372101c9b17bSDave Hansen system calls and interrupts. 372201c9b17bSDave Hansen 372301c9b17bSDave Hansen on - unconditionally enable 372401c9b17bSDave Hansen off - unconditionally disable 372501c9b17bSDave Hansen auto - kernel detects whether your CPU model is 372601c9b17bSDave Hansen vulnerable to issues that PTI mitigates 372701c9b17bSDave Hansen 372801c9b17bSDave Hansen Not specifying this option is equivalent to pti=auto. 372901c9b17bSDave Hansen 373001c9b17bSDave Hansen nopti [X86_64] 373101c9b17bSDave Hansen Equivalent to pti=off 373241f4c20bSBorislav Petkov 3733e52347bdSJani Nikula pty.legacy_count= 3734e52347bdSJani Nikula [KNL] Number of legacy pty's. Overwrites compiled-in 3735e52347bdSJani Nikula default number. 3736e52347bdSJani Nikula 3737e52347bdSJani Nikula quiet [KNL] Disable most log messages 3738e52347bdSJani Nikula 3739e52347bdSJani Nikula r128= [HW,DRM] 3740e52347bdSJani Nikula 3741e52347bdSJani Nikula raid= [HW,RAID] 3742e52347bdSJani Nikula See Documentation/admin-guide/md.rst. 3743e52347bdSJani Nikula 3744e52347bdSJani Nikula ramdisk_size= [RAM] Sizes of RAM disks in kilobytes 3745e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/ramdisk.rst. 3746e52347bdSJani Nikula 37479b254366SKees Cook random.trust_cpu={on,off} 37489b254366SKees Cook [KNL] Enable or disable trusting the use of the 37499b254366SKees Cook CPU's random number generator (if available) to 37509b254366SKees Cook fully seed the kernel's CRNG. Default is controlled 37519b254366SKees Cook by CONFIG_RANDOM_TRUST_CPU. 37529b254366SKees Cook 3753011d8261SBorislav Petkov ras=option[,option,...] [KNL] RAS-specific options 3754011d8261SBorislav Petkov 3755011d8261SBorislav Petkov cec_disable [X86] 3756011d8261SBorislav Petkov Disable the Correctable Errors Collector, 3757011d8261SBorislav Petkov see CONFIG_RAS_CEC help text. 3758011d8261SBorislav Petkov 3759e52347bdSJani Nikula rcu_nocbs= [KNL] 3760da8739f2SPaul E. McKenney The argument is a cpu list, as described above, 3761da8739f2SPaul E. McKenney except that the string "all" can be used to 3762da8739f2SPaul E. McKenney specify every CPU on the system. 3763e52347bdSJani Nikula 3764e52347bdSJani Nikula In kernels built with CONFIG_RCU_NOCB_CPU=y, set 3765e52347bdSJani Nikula the specified list of CPUs to be no-callback CPUs. 376677095901SPaul E. McKenney Invocation of these CPUs' RCU callbacks will be 376777095901SPaul E. McKenney offloaded to "rcuox/N" kthreads created for that 376877095901SPaul E. McKenney purpose, where "x" is "p" for RCU-preempt, and 376977095901SPaul E. McKenney "s" for RCU-sched, and "N" is the CPU number. 377077095901SPaul E. McKenney This reduces OS jitter on the offloaded CPUs, 377177095901SPaul E. McKenney which can be useful for HPC and real-time 377277095901SPaul E. McKenney workloads. It can also improve energy efficiency 377377095901SPaul E. McKenney for asymmetric multiprocessors. 3774e52347bdSJani Nikula 3775e52347bdSJani Nikula rcu_nocb_poll [KNL] 3776e52347bdSJani Nikula Rather than requiring that offloaded CPUs 3777e52347bdSJani Nikula (specified by rcu_nocbs= above) explicitly 3778e52347bdSJani Nikula awaken the corresponding "rcuoN" kthreads, 3779e52347bdSJani Nikula make these kthreads poll for callbacks. 3780e52347bdSJani Nikula This improves the real-time response for the 3781e52347bdSJani Nikula offloaded CPUs by relieving them of the need to 3782e52347bdSJani Nikula wake up the corresponding kthread, but degrades 3783e52347bdSJani Nikula energy efficiency by requiring that the kthreads 3784e52347bdSJani Nikula periodically wake up to do the polling. 3785e52347bdSJani Nikula 3786e52347bdSJani Nikula rcutree.blimit= [KNL] 3787e52347bdSJani Nikula Set maximum number of finished RCU callbacks to 3788e52347bdSJani Nikula process in one batch. 3789e52347bdSJani Nikula 3790e52347bdSJani Nikula rcutree.dump_tree= [KNL] 3791e52347bdSJani Nikula Dump the structure of the rcu_node combining tree 3792e52347bdSJani Nikula out at early boot. This is used for diagnostic 3793e52347bdSJani Nikula purposes, to verify correct tree setup. 3794e52347bdSJani Nikula 3795e52347bdSJani Nikula rcutree.gp_cleanup_delay= [KNL] 3796e52347bdSJani Nikula Set the number of jiffies to delay each step of 379790040c9eSPaul E. McKenney RCU grace-period cleanup. 3798e52347bdSJani Nikula 3799e52347bdSJani Nikula rcutree.gp_init_delay= [KNL] 3800e52347bdSJani Nikula Set the number of jiffies to delay each step of 380190040c9eSPaul E. McKenney RCU grace-period initialization. 3802e52347bdSJani Nikula 3803e52347bdSJani Nikula rcutree.gp_preinit_delay= [KNL] 3804e52347bdSJani Nikula Set the number of jiffies to delay each step of 3805e52347bdSJani Nikula RCU grace-period pre-initialization, that is, 3806e52347bdSJani Nikula the propagation of recent CPU-hotplug changes up 380790040c9eSPaul E. McKenney the rcu_node combining tree. 3808e52347bdSJani Nikula 380948d07c04SSebastian Andrzej Siewior rcutree.use_softirq= [KNL] 381048d07c04SSebastian Andrzej Siewior If set to zero, move all RCU_SOFTIRQ processing to 381148d07c04SSebastian Andrzej Siewior per-CPU rcuc kthreads. Defaults to a non-zero 381248d07c04SSebastian Andrzej Siewior value, meaning that RCU_SOFTIRQ is used by default. 381348d07c04SSebastian Andrzej Siewior Specify rcutree.use_softirq=0 to use rcuc kthreads. 381448d07c04SSebastian Andrzej Siewior 3815e52347bdSJani Nikula rcutree.rcu_fanout_exact= [KNL] 3816e52347bdSJani Nikula Disable autobalancing of the rcu_node combining 3817e52347bdSJani Nikula tree. This is used by rcutorture, and might 3818e52347bdSJani Nikula possibly be useful for architectures having high 3819e52347bdSJani Nikula cache-to-cache transfer latencies. 3820e52347bdSJani Nikula 3821e52347bdSJani Nikula rcutree.rcu_fanout_leaf= [KNL] 3822e52347bdSJani Nikula Change the number of CPUs assigned to each 3823e52347bdSJani Nikula leaf rcu_node structure. Useful for very 3824e52347bdSJani Nikula large systems, which will choose the value 64, 3825e52347bdSJani Nikula and for NUMA systems with large remote-access 3826e52347bdSJani Nikula latencies, which will choose a value aligned 3827e52347bdSJani Nikula with the appropriate hardware boundaries. 3828e52347bdSJani Nikula 3829e52347bdSJani Nikula rcutree.jiffies_till_first_fqs= [KNL] 3830e52347bdSJani Nikula Set delay from grace-period initialization to 3831e52347bdSJani Nikula first attempt to force quiescent states. 3832e52347bdSJani Nikula Units are jiffies, minimum value is zero, 3833e52347bdSJani Nikula and maximum value is HZ. 3834e52347bdSJani Nikula 3835e52347bdSJani Nikula rcutree.jiffies_till_next_fqs= [KNL] 3836e52347bdSJani Nikula Set delay between subsequent attempts to force 3837e52347bdSJani Nikula quiescent states. Units are jiffies, minimum 3838e52347bdSJani Nikula value is one, and maximum value is HZ. 3839e52347bdSJani Nikula 38401a4762b9SPaul E. McKenney rcutree.jiffies_till_sched_qs= [KNL] 38411a4762b9SPaul E. McKenney Set required age in jiffies for a 38421a4762b9SPaul E. McKenney given grace period before RCU starts 38431a4762b9SPaul E. McKenney soliciting quiescent-state help from 38441a4762b9SPaul E. McKenney rcu_note_context_switch() and cond_resched(). 38451a4762b9SPaul E. McKenney If not specified, the kernel will calculate 38461a4762b9SPaul E. McKenney a value based on the most recent settings 38471a4762b9SPaul E. McKenney of rcutree.jiffies_till_first_fqs 38481a4762b9SPaul E. McKenney and rcutree.jiffies_till_next_fqs. 38491a4762b9SPaul E. McKenney This calculated value may be viewed in 38501a4762b9SPaul E. McKenney rcutree.jiffies_to_sched_qs. Any attempt to set 38511a4762b9SPaul E. McKenney rcutree.jiffies_to_sched_qs will be cheerfully 38521a4762b9SPaul E. McKenney overwritten. 38531a4762b9SPaul E. McKenney 3854e52347bdSJani Nikula rcutree.kthread_prio= [KNL,BOOT] 3855e52347bdSJani Nikula Set the SCHED_FIFO priority of the RCU per-CPU 3856e52347bdSJani Nikula kthreads (rcuc/N). This value is also used for 3857e52347bdSJani Nikula the priority of the RCU boost threads (rcub/N) 3858e52347bdSJani Nikula and for the RCU grace-period kthreads (rcu_bh, 3859e52347bdSJani Nikula rcu_preempt, and rcu_sched). If RCU_BOOST is 3860e52347bdSJani Nikula set, valid values are 1-99 and the default is 1 3861e52347bdSJani Nikula (the least-favored priority). Otherwise, when 3862e52347bdSJani Nikula RCU_BOOST is not set, valid values are 0-99 and 3863e52347bdSJani Nikula the default is zero (non-realtime operation). 3864e52347bdSJani Nikula 3865f7c612b0SPaul E. McKenney rcutree.rcu_nocb_gp_stride= [KNL] 3866f7c612b0SPaul E. McKenney Set the number of NOCB callback kthreads in 3867f7c612b0SPaul E. McKenney each group, which defaults to the square root 3868f7c612b0SPaul E. McKenney of the number of CPUs. Larger numbers reduce 3869f7c612b0SPaul E. McKenney the wakeup overhead on the global grace-period 3870f7c612b0SPaul E. McKenney kthread, but increases that same overhead on 3871f7c612b0SPaul E. McKenney each group's NOCB grace-period kthread. 3872e52347bdSJani Nikula 3873e52347bdSJani Nikula rcutree.qhimark= [KNL] 3874e52347bdSJani Nikula Set threshold of queued RCU callbacks beyond which 3875e52347bdSJani Nikula batch limiting is disabled. 3876e52347bdSJani Nikula 3877e52347bdSJani Nikula rcutree.qlowmark= [KNL] 3878e52347bdSJani Nikula Set threshold of queued RCU callbacks below which 3879e52347bdSJani Nikula batch limiting is re-enabled. 3880e52347bdSJani Nikula 3881e52347bdSJani Nikula rcutree.rcu_idle_gp_delay= [KNL] 3882e52347bdSJani Nikula Set wakeup interval for idle CPUs that have 3883e52347bdSJani Nikula RCU callbacks (RCU_FAST_NO_HZ=y). 3884e52347bdSJani Nikula 3885e52347bdSJani Nikula rcutree.rcu_idle_lazy_gp_delay= [KNL] 3886e52347bdSJani Nikula Set wakeup interval for idle CPUs that have 3887e52347bdSJani Nikula only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y). 3888e52347bdSJani Nikula Lazy RCU callbacks are those which RCU can 3889e52347bdSJani Nikula prove do nothing more than free memory. 3890e52347bdSJani Nikula 3891e3c50dfbSPaul E. McKenney rcutree.rcu_kick_kthreads= [KNL] 3892e3c50dfbSPaul E. McKenney Cause the grace-period kthread to get an extra 3893e3c50dfbSPaul E. McKenney wake_up() if it sleeps three times longer than 3894e3c50dfbSPaul E. McKenney it should at force-quiescent-state time. 3895e3c50dfbSPaul E. McKenney This wake_up() will be accompanied by a 3896e3c50dfbSPaul E. McKenney WARN_ONCE() splat and an ftrace_dump(). 3897e3c50dfbSPaul E. McKenney 38982ccaff10SPaul E. McKenney rcutree.sysrq_rcu= [KNL] 38992ccaff10SPaul E. McKenney Commandeer a sysrq key to dump out Tree RCU's 39002ccaff10SPaul E. McKenney rcu_node tree with an eye towards determining 39012ccaff10SPaul E. McKenney why a new grace period has not yet started. 39022ccaff10SPaul E. McKenney 3903881ed593SPaul E. McKenney rcuperf.gp_async= [KNL] 3904881ed593SPaul E. McKenney Measure performance of asynchronous 3905881ed593SPaul E. McKenney grace-period primitives such as call_rcu(). 3906881ed593SPaul E. McKenney 3907881ed593SPaul E. McKenney rcuperf.gp_async_max= [KNL] 3908881ed593SPaul E. McKenney Specify the maximum number of outstanding 3909881ed593SPaul E. McKenney callbacks per writer thread. When a writer 3910881ed593SPaul E. McKenney thread exceeds this limit, it invokes the 3911881ed593SPaul E. McKenney corresponding flavor of rcu_barrier() to allow 3912881ed593SPaul E. McKenney previously posted callbacks to drain. 3913881ed593SPaul E. McKenney 3914e52347bdSJani Nikula rcuperf.gp_exp= [KNL] 3915e52347bdSJani Nikula Measure performance of expedited synchronous 3916e52347bdSJani Nikula grace-period primitives. 3917e52347bdSJani Nikula 3918e52347bdSJani Nikula rcuperf.holdoff= [KNL] 3919e52347bdSJani Nikula Set test-start holdoff period. The purpose of 3920e52347bdSJani Nikula this parameter is to delay the start of the 3921e52347bdSJani Nikula test until boot completes in order to avoid 3922e52347bdSJani Nikula interference. 3923e52347bdSJani Nikula 3924e52347bdSJani Nikula rcuperf.nreaders= [KNL] 3925e52347bdSJani Nikula Set number of RCU readers. The value -1 selects 3926e52347bdSJani Nikula N, where N is the number of CPUs. A value 3927e52347bdSJani Nikula "n" less than -1 selects N-n+1, where N is again 3928e52347bdSJani Nikula the number of CPUs. For example, -2 selects N 3929e52347bdSJani Nikula (the number of CPUs), -3 selects N+1, and so on. 3930e52347bdSJani Nikula A value of "n" less than or equal to -N selects 3931e52347bdSJani Nikula a single reader. 3932e52347bdSJani Nikula 3933e52347bdSJani Nikula rcuperf.nwriters= [KNL] 3934e52347bdSJani Nikula Set number of RCU writers. The values operate 3935e52347bdSJani Nikula the same as for rcuperf.nreaders. 3936e52347bdSJani Nikula N, where N is the number of CPUs 3937e52347bdSJani Nikula 3938820687a7SPaul E. McKenney rcuperf.perf_type= [KNL] 3939820687a7SPaul E. McKenney Specify the RCU implementation to test. 3940820687a7SPaul E. McKenney 3941e52347bdSJani Nikula rcuperf.shutdown= [KNL] 3942e52347bdSJani Nikula Shut the system down after performance tests 3943e52347bdSJani Nikula complete. This is useful for hands-off automated 3944e52347bdSJani Nikula testing. 3945e52347bdSJani Nikula 3946e52347bdSJani Nikula rcuperf.verbose= [KNL] 3947e52347bdSJani Nikula Enable additional printk() statements. 3948e52347bdSJani Nikula 3949820687a7SPaul E. McKenney rcuperf.writer_holdoff= [KNL] 3950820687a7SPaul E. McKenney Write-side holdoff between grace periods, 3951820687a7SPaul E. McKenney in microseconds. The default of zero says 3952820687a7SPaul E. McKenney no holdoff. 3953820687a7SPaul E. McKenney 3954e52347bdSJani Nikula rcutorture.fqs_duration= [KNL] 3955e52347bdSJani Nikula Set duration of force_quiescent_state bursts 3956e52347bdSJani Nikula in microseconds. 3957e52347bdSJani Nikula 3958e52347bdSJani Nikula rcutorture.fqs_holdoff= [KNL] 3959e52347bdSJani Nikula Set holdoff time within force_quiescent_state bursts 3960e52347bdSJani Nikula in microseconds. 3961e52347bdSJani Nikula 3962e52347bdSJani Nikula rcutorture.fqs_stutter= [KNL] 3963e52347bdSJani Nikula Set wait time between force_quiescent_state bursts 3964e52347bdSJani Nikula in seconds. 3965e52347bdSJani Nikula 3966ed8f6fb2SPaul E. McKenney rcutorture.fwd_progress= [KNL] 3967ed8f6fb2SPaul E. McKenney Enable RCU grace-period forward-progress testing 3968ed8f6fb2SPaul E. McKenney for the types of RCU supporting this notion. 3969ed8f6fb2SPaul E. McKenney 3970ed8f6fb2SPaul E. McKenney rcutorture.fwd_progress_div= [KNL] 3971ed8f6fb2SPaul E. McKenney Specify the fraction of a CPU-stall-warning 3972ed8f6fb2SPaul E. McKenney period to do tight-loop forward-progress testing. 3973ed8f6fb2SPaul E. McKenney 3974ed8f6fb2SPaul E. McKenney rcutorture.fwd_progress_holdoff= [KNL] 3975ed8f6fb2SPaul E. McKenney Number of seconds to wait between successive 3976ed8f6fb2SPaul E. McKenney forward-progress tests. 3977ed8f6fb2SPaul E. McKenney 3978ed8f6fb2SPaul E. McKenney rcutorture.fwd_progress_need_resched= [KNL] 3979ed8f6fb2SPaul E. McKenney Enclose cond_resched() calls within checks for 3980ed8f6fb2SPaul E. McKenney need_resched() during tight-loop forward-progress 3981ed8f6fb2SPaul E. McKenney testing. 3982ed8f6fb2SPaul E. McKenney 3983e52347bdSJani Nikula rcutorture.gp_cond= [KNL] 3984e52347bdSJani Nikula Use conditional/asynchronous update-side 3985e52347bdSJani Nikula primitives, if available. 3986e52347bdSJani Nikula 3987e52347bdSJani Nikula rcutorture.gp_exp= [KNL] 3988e52347bdSJani Nikula Use expedited update-side primitives, if available. 3989e52347bdSJani Nikula 3990e52347bdSJani Nikula rcutorture.gp_normal= [KNL] 3991e52347bdSJani Nikula Use normal (non-expedited) asynchronous 3992e52347bdSJani Nikula update-side primitives, if available. 3993e52347bdSJani Nikula 3994e52347bdSJani Nikula rcutorture.gp_sync= [KNL] 3995e52347bdSJani Nikula Use normal (non-expedited) synchronous 3996e52347bdSJani Nikula update-side primitives, if available. If all 3997e52347bdSJani Nikula of rcutorture.gp_cond=, rcutorture.gp_exp=, 3998e52347bdSJani Nikula rcutorture.gp_normal=, and rcutorture.gp_sync= 3999e52347bdSJani Nikula are zero, rcutorture acts as if is interpreted 4000e52347bdSJani Nikula they are all non-zero. 4001e52347bdSJani Nikula 4002e52347bdSJani Nikula rcutorture.n_barrier_cbs= [KNL] 4003e52347bdSJani Nikula Set callbacks/threads for rcu_barrier() testing. 4004e52347bdSJani Nikula 4005e52347bdSJani Nikula rcutorture.nfakewriters= [KNL] 4006e52347bdSJani Nikula Set number of concurrent RCU writers. These just 4007e52347bdSJani Nikula stress RCU, they don't participate in the actual 4008e52347bdSJani Nikula test, hence the "fake". 4009e52347bdSJani Nikula 4010e52347bdSJani Nikula rcutorture.nreaders= [KNL] 4011e52347bdSJani Nikula Set number of RCU readers. The value -1 selects 4012e52347bdSJani Nikula N-1, where N is the number of CPUs. A value 4013e52347bdSJani Nikula "n" less than -1 selects N-n-2, where N is again 4014e52347bdSJani Nikula the number of CPUs. For example, -2 selects N 4015e52347bdSJani Nikula (the number of CPUs), -3 selects N+1, and so on. 4016e52347bdSJani Nikula 4017e52347bdSJani Nikula rcutorture.object_debug= [KNL] 4018e52347bdSJani Nikula Enable debug-object double-call_rcu() testing. 4019e52347bdSJani Nikula 4020e52347bdSJani Nikula rcutorture.onoff_holdoff= [KNL] 4021e52347bdSJani Nikula Set time (s) after boot for CPU-hotplug testing. 4022e52347bdSJani Nikula 4023e52347bdSJani Nikula rcutorture.onoff_interval= [KNL] 4024028be12bSPaul E. McKenney Set time (jiffies) between CPU-hotplug operations, 4025028be12bSPaul E. McKenney or zero to disable CPU-hotplug testing. 4026e52347bdSJani Nikula 4027e52347bdSJani Nikula rcutorture.shuffle_interval= [KNL] 4028e52347bdSJani Nikula Set task-shuffle interval (s). Shuffling tasks 4029e52347bdSJani Nikula allows some CPUs to go into dyntick-idle mode 4030e52347bdSJani Nikula during the rcutorture test. 4031e52347bdSJani Nikula 4032e52347bdSJani Nikula rcutorture.shutdown_secs= [KNL] 4033e52347bdSJani Nikula Set time (s) after boot system shutdown. This 4034e52347bdSJani Nikula is useful for hands-off automated testing. 4035e52347bdSJani Nikula 4036e52347bdSJani Nikula rcutorture.stall_cpu= [KNL] 4037e52347bdSJani Nikula Duration of CPU stall (s) to test RCU CPU stall 4038e52347bdSJani Nikula warnings, zero to disable. 4039e52347bdSJani Nikula 4040e52347bdSJani Nikula rcutorture.stall_cpu_holdoff= [KNL] 4041e52347bdSJani Nikula Time to wait (s) after boot before inducing stall. 4042e52347bdSJani Nikula 40432b1516e5SPaul E. McKenney rcutorture.stall_cpu_irqsoff= [KNL] 40442b1516e5SPaul E. McKenney Disable interrupts while stalling if set. 40452b1516e5SPaul E. McKenney 4046e52347bdSJani Nikula rcutorture.stat_interval= [KNL] 4047e52347bdSJani Nikula Time (s) between statistics printk()s. 4048e52347bdSJani Nikula 4049e52347bdSJani Nikula rcutorture.stutter= [KNL] 4050e52347bdSJani Nikula Time (s) to stutter testing, for example, specifying 4051e52347bdSJani Nikula five seconds causes the test to run for five seconds, 4052e52347bdSJani Nikula wait for five seconds, and so on. This tests RCU's 4053e52347bdSJani Nikula ability to transition abruptly to and from idle. 4054e52347bdSJani Nikula 4055e52347bdSJani Nikula rcutorture.test_boost= [KNL] 4056e52347bdSJani Nikula Test RCU priority boosting? 0=no, 1=maybe, 2=yes. 4057e52347bdSJani Nikula "Maybe" means test if the RCU implementation 4058e52347bdSJani Nikula under test support RCU priority boosting. 4059e52347bdSJani Nikula 4060e52347bdSJani Nikula rcutorture.test_boost_duration= [KNL] 4061e52347bdSJani Nikula Duration (s) of each individual boost test. 4062e52347bdSJani Nikula 4063e52347bdSJani Nikula rcutorture.test_boost_interval= [KNL] 4064e52347bdSJani Nikula Interval (s) between each boost test. 4065e52347bdSJani Nikula 4066e52347bdSJani Nikula rcutorture.test_no_idle_hz= [KNL] 4067e52347bdSJani Nikula Test RCU's dyntick-idle handling. See also the 4068e52347bdSJani Nikula rcutorture.shuffle_interval parameter. 4069e52347bdSJani Nikula 4070e52347bdSJani Nikula rcutorture.torture_type= [KNL] 4071e52347bdSJani Nikula Specify the RCU implementation to test. 4072e52347bdSJani Nikula 4073e52347bdSJani Nikula rcutorture.verbose= [KNL] 4074e52347bdSJani Nikula Enable additional printk() statements. 4075e52347bdSJani Nikula 4076cdc694b2SPaul E. McKenney rcupdate.rcu_cpu_stall_ftrace_dump= [KNL] 4077cdc694b2SPaul E. McKenney Dump ftrace buffer after reporting RCU CPU 4078cdc694b2SPaul E. McKenney stall warning. 4079cdc694b2SPaul E. McKenney 4080e52347bdSJani Nikula rcupdate.rcu_cpu_stall_suppress= [KNL] 4081e52347bdSJani Nikula Suppress RCU CPU stall warning messages. 4082e52347bdSJani Nikula 4083e52347bdSJani Nikula rcupdate.rcu_cpu_stall_timeout= [KNL] 4084e52347bdSJani Nikula Set timeout for RCU CPU stall warning messages. 4085e52347bdSJani Nikula 4086e52347bdSJani Nikula rcupdate.rcu_expedited= [KNL] 4087e52347bdSJani Nikula Use expedited grace-period primitives, for 4088e52347bdSJani Nikula example, synchronize_rcu_expedited() instead 4089e52347bdSJani Nikula of synchronize_rcu(). This reduces latency, 4090e52347bdSJani Nikula but can increase CPU utilization, degrade 4091e52347bdSJani Nikula real-time latency, and degrade energy efficiency. 4092e52347bdSJani Nikula No effect on CONFIG_TINY_RCU kernels. 4093e52347bdSJani Nikula 4094e52347bdSJani Nikula rcupdate.rcu_normal= [KNL] 4095e52347bdSJani Nikula Use only normal grace-period primitives, 4096e52347bdSJani Nikula for example, synchronize_rcu() instead of 4097e52347bdSJani Nikula synchronize_rcu_expedited(). This improves 4098e52347bdSJani Nikula real-time latency, CPU utilization, and 4099e52347bdSJani Nikula energy efficiency, but can expose users to 4100e52347bdSJani Nikula increased grace-period latency. This parameter 4101e52347bdSJani Nikula overrides rcupdate.rcu_expedited. No effect on 4102e52347bdSJani Nikula CONFIG_TINY_RCU kernels. 4103e52347bdSJani Nikula 4104e52347bdSJani Nikula rcupdate.rcu_normal_after_boot= [KNL] 4105e52347bdSJani Nikula Once boot has completed (that is, after 4106e52347bdSJani Nikula rcu_end_inkernel_boot() has been invoked), use 4107e52347bdSJani Nikula only normal grace-period primitives. No effect 4108e52347bdSJani Nikula on CONFIG_TINY_RCU kernels. 4109e52347bdSJani Nikula 4110e52347bdSJani Nikula rcupdate.rcu_task_stall_timeout= [KNL] 4111e52347bdSJani Nikula Set timeout in jiffies for RCU task stall warning 4112e52347bdSJani Nikula messages. Disable with a value less than or equal 4113e52347bdSJani Nikula to zero. 4114e52347bdSJani Nikula 4115e52347bdSJani Nikula rcupdate.rcu_self_test= [KNL] 4116e52347bdSJani Nikula Run the RCU early boot self tests 4117e52347bdSJani Nikula 4118e52347bdSJani Nikula rdinit= [KNL] 4119e52347bdSJani Nikula Format: <full_path> 4120e52347bdSJani Nikula Run specified binary instead of /init from the ramdisk, 4121e52347bdSJani Nikula used for early userspace startup. See initrd. 4122e52347bdSJani Nikula 4123c49a0a80STom Lendacky rdrand= [X86] 4124c49a0a80STom Lendacky force - Override the decision by the kernel to hide the 4125c49a0a80STom Lendacky advertisement of RDRAND support (this affects 4126c49a0a80STom Lendacky certain AMD processors because of buggy BIOS 4127c49a0a80STom Lendacky support, specifically around the suspend/resume 4128c49a0a80STom Lendacky path). 4129c49a0a80STom Lendacky 41301d9807fcSTony Luck rdt= [HW,X86,RDT] 41311d9807fcSTony Luck Turn on/off individual RDT features. List is: 413231516de3SFenghua Yu cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp, 413331516de3SFenghua Yu mba. 41341d9807fcSTony Luck E.g. to turn on cmt and turn off mba use: 41351d9807fcSTony Luck rdt=cmt,!mba 41361d9807fcSTony Luck 4137e52347bdSJani Nikula reboot= [KNL] 4138e52347bdSJani Nikula Format (x86 or x86_64): 4139e52347bdSJani Nikula [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \ 4140e52347bdSJani Nikula [[,]s[mp]#### \ 4141e52347bdSJani Nikula [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \ 4142e52347bdSJani Nikula [[,]f[orce] 4143b287a25aSAaro Koskinen Where reboot_mode is one of warm (soft) or cold (hard) or gpio 4144b287a25aSAaro Koskinen (prefix with 'panic_' to set mode for panic 4145b287a25aSAaro Koskinen reboot only), 4146e52347bdSJani Nikula reboot_type is one of bios, acpi, kbd, triple, efi, or pci, 4147e52347bdSJani Nikula reboot_force is either force or not specified, 4148e52347bdSJani Nikula reboot_cpu is s[mp]#### with #### being the processor 4149e52347bdSJani Nikula to be used for rebooting. 4150e52347bdSJani Nikula 4151e52347bdSJani Nikula relax_domain_level= 4152e52347bdSJani Nikula [KNL, SMP] Set scheduler's default relax_domain_level. 4153da82c92fSMauro Carvalho Chehab See Documentation/admin-guide/cgroup-v1/cpusets.rst. 4154e52347bdSJani Nikula 4155ffd2e8dfSBjorn Helgaas reserve= [KNL,BUGS] Force kernel to ignore I/O ports or memory 4156ffd2e8dfSBjorn Helgaas Format: <base1>,<size1>[,<base2>,<size2>,...] 4157ffd2e8dfSBjorn Helgaas Reserve I/O ports or memory so the kernel won't use 4158ffd2e8dfSBjorn Helgaas them. If <base> is less than 0x10000, the region 4159ffd2e8dfSBjorn Helgaas is assumed to be I/O ports; otherwise it is memory. 4160e52347bdSJani Nikula 4161e52347bdSJani Nikula reservetop= [X86-32] 4162e52347bdSJani Nikula Format: nn[KMG] 4163e52347bdSJani Nikula Reserves a hole at the top of the kernel virtual 4164e52347bdSJani Nikula address space. 4165e52347bdSJani Nikula 4166e52347bdSJani Nikula reservelow= [X86] 4167e52347bdSJani Nikula Format: nn[K] 4168e52347bdSJani Nikula Set the amount of memory to reserve for BIOS at 4169e52347bdSJani Nikula the bottom of the address space. 4170e52347bdSJani Nikula 4171e52347bdSJani Nikula reset_devices [KNL] Force drivers to reset the underlying device 4172e52347bdSJani Nikula during initialization. 4173e52347bdSJani Nikula 4174e52347bdSJani Nikula resume= [SWSUSP] 4175e52347bdSJani Nikula Specify the partition device for software suspend 4176e52347bdSJani Nikula Format: 4177e52347bdSJani Nikula {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>} 4178e52347bdSJani Nikula 4179e52347bdSJani Nikula resume_offset= [SWSUSP] 4180e52347bdSJani Nikula Specify the offset from the beginning of the partition 4181e52347bdSJani Nikula given by "resume=" at which the swap header is located, 4182e52347bdSJani Nikula in <PAGE_SIZE> units (needed only for swap files). 4183151f4e2bSMauro Carvalho Chehab See Documentation/power/swsusp-and-swap-files.rst 4184e52347bdSJani Nikula 4185e52347bdSJani Nikula resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to 4186e52347bdSJani Nikula read the resume files 4187e52347bdSJani Nikula 4188e52347bdSJani Nikula resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up. 4189e52347bdSJani Nikula Useful for devices that are detected asynchronously 4190e52347bdSJani Nikula (e.g. USB and MMC devices). 4191e52347bdSJani Nikula 4192e52347bdSJani Nikula hibernate= [HIBERNATION] 4193e52347bdSJani Nikula noresume Don't check if there's a hibernation image 4194e52347bdSJani Nikula present during boot. 4195e52347bdSJani Nikula nocompress Don't compress/decompress hibernation images. 4196e52347bdSJani Nikula no Disable hibernation and resume. 4197e52347bdSJani Nikula protect_image Turn on image protection during restoration 4198e52347bdSJani Nikula (that will set all pages holding image data 4199e52347bdSJani Nikula during restoration read-only). 4200e52347bdSJani Nikula 4201e52347bdSJani Nikula retain_initrd [RAM] Keep initrd memory after extraction 4202e52347bdSJani Nikula 4203e52347bdSJani Nikula rfkill.default_state= 4204e52347bdSJani Nikula 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm, 4205e52347bdSJani Nikula etc. communication is blocked by default. 4206e52347bdSJani Nikula 1 Unblocked. 4207e52347bdSJani Nikula 4208e52347bdSJani Nikula rfkill.master_switch_mode= 4209e52347bdSJani Nikula 0 The "airplane mode" button does nothing. 4210e52347bdSJani Nikula 1 The "airplane mode" button toggles between everything 4211e52347bdSJani Nikula blocked and the previous configuration. 4212e52347bdSJani Nikula 2 The "airplane mode" button toggles between everything 4213e52347bdSJani Nikula blocked and everything unblocked. 4214e52347bdSJani Nikula 4215e52347bdSJani Nikula rhash_entries= [KNL,NET] 4216e52347bdSJani Nikula Set number of hash buckets for route cache 4217e52347bdSJani Nikula 4218e16fd002SGrzegorz Andrejczuk ring3mwait=disable 4219e16fd002SGrzegorz Andrejczuk [KNL] Disable ring 3 MONITOR/MWAIT feature on supported 4220e16fd002SGrzegorz Andrejczuk CPUs. 4221e16fd002SGrzegorz Andrejczuk 4222e52347bdSJani Nikula ro [KNL] Mount root device read-only on boot 4223e52347bdSJani Nikula 4224e52347bdSJani Nikula rodata= [KNL] 4225e52347bdSJani Nikula on Mark read-only kernel memory as read-only (default). 4226e52347bdSJani Nikula off Leave read-only kernel memory writable for debugging. 4227e52347bdSJani Nikula 4228e52347bdSJani Nikula rockchip.usb_uart 4229e52347bdSJani Nikula Enable the uart passthrough on the designated usb port 4230e52347bdSJani Nikula on Rockchip SoCs. When active, the signals of the 4231e52347bdSJani Nikula debug-uart get routed to the D+ and D- pins of the usb 4232e52347bdSJani Nikula port and the regular usb controller gets disabled. 4233e52347bdSJani Nikula 4234e52347bdSJani Nikula root= [KNL] Root filesystem 4235e52347bdSJani Nikula See name_to_dev_t comment in init/do_mounts.c. 4236e52347bdSJani Nikula 4237e52347bdSJani Nikula rootdelay= [KNL] Delay (in seconds) to pause before attempting to 4238e52347bdSJani Nikula mount the root filesystem 4239e52347bdSJani Nikula 4240e52347bdSJani Nikula rootflags= [KNL] Set root filesystem mount option string 4241e52347bdSJani Nikula 4242e52347bdSJani Nikula rootfstype= [KNL] Set root filesystem type 4243e52347bdSJani Nikula 4244e52347bdSJani Nikula rootwait [KNL] Wait (indefinitely) for root device to show up. 4245e52347bdSJani Nikula Useful for devices that are detected asynchronously 4246e52347bdSJani Nikula (e.g. USB and MMC devices). 4247e52347bdSJani Nikula 4248e52347bdSJani Nikula rproc_mem=nn[KMG][@address] 4249e52347bdSJani Nikula [KNL,ARM,CMA] Remoteproc physical memory block. 4250e52347bdSJani Nikula Memory area to be used by remote processor image, 4251e52347bdSJani Nikula managed by CMA. 4252e52347bdSJani Nikula 4253e52347bdSJani Nikula rw [KNL] Mount root device read-write on boot 4254e52347bdSJani Nikula 4255e52347bdSJani Nikula S [KNL] Run init in single mode 4256e52347bdSJani Nikula 4257e52347bdSJani Nikula s390_iommu= [HW,S390] 4258e52347bdSJani Nikula Set s390 IOTLB flushing mode 4259e52347bdSJani Nikula strict 4260e52347bdSJani Nikula With strict flushing every unmap operation will result in 4261e52347bdSJani Nikula an IOTLB flush. Default is lazy flushing before reuse, 4262e52347bdSJani Nikula which is faster. 4263e52347bdSJani Nikula 4264e52347bdSJani Nikula sa1100ir [NET] 4265e52347bdSJani Nikula See drivers/net/irda/sa1100_ir.c. 4266e52347bdSJani Nikula 4267e52347bdSJani Nikula sbni= [NET] Granch SBNI12 leased line adapter 4268e52347bdSJani Nikula 4269e52347bdSJani Nikula sched_debug [KNL] Enables verbose scheduler debug messages. 4270e52347bdSJani Nikula 4271e52347bdSJani Nikula schedstats= [KNL,X86] Enable or disable scheduled statistics. 4272e52347bdSJani Nikula Allowed values are enable and disable. This feature 4273e52347bdSJani Nikula incurs a small amount of overhead in the scheduler 4274e52347bdSJani Nikula but is useful for debugging and performance tuning. 4275e52347bdSJani Nikula 4276e52347bdSJani Nikula skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate 4277e52347bdSJani Nikula xtime_lock contention on larger systems, and/or RCU lock 4278e52347bdSJani Nikula contention on all systems with CONFIG_MAXSMP set. 4279e52347bdSJani Nikula Format: { "0" | "1" } 4280e52347bdSJani Nikula 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1" 4281e52347bdSJani Nikula 1 -- enable. 4282e52347bdSJani Nikula Note: increases power consumption, thus should only be 4283e52347bdSJani Nikula enabled if running jitter sensitive (HPC/RT) workloads. 4284e52347bdSJani Nikula 428589a9684eSKees Cook security= [SECURITY] Choose a legacy "major" security module to 428689a9684eSKees Cook enable at boot. This has been deprecated by the 428789a9684eSKees Cook "lsm=" parameter. 4288e52347bdSJani Nikula 4289e52347bdSJani Nikula selinux= [SELINUX] Disable or enable SELinux at boot time. 4290e52347bdSJani Nikula Format: { "0" | "1" } 4291e52347bdSJani Nikula See security/selinux/Kconfig help text. 4292e52347bdSJani Nikula 0 -- disable. 4293e52347bdSJani Nikula 1 -- enable. 4294e52347bdSJani Nikula Default value is set via kernel config option. 4295e52347bdSJani Nikula If enabled at boot time, /selinux/disable can be used 4296e52347bdSJani Nikula later to disable prior to initial policy load. 4297e52347bdSJani Nikula 4298e52347bdSJani Nikula apparmor= [APPARMOR] Disable or enable AppArmor at boot time 4299e52347bdSJani Nikula Format: { "0" | "1" } 4300e52347bdSJani Nikula See security/apparmor/Kconfig help text 4301e52347bdSJani Nikula 0 -- disable. 4302e52347bdSJani Nikula 1 -- enable. 4303e52347bdSJani Nikula Default value is set via kernel config option. 4304e52347bdSJani Nikula 4305e52347bdSJani Nikula serialnumber [BUGS=X86-32] 4306e52347bdSJani Nikula 4307e52347bdSJani Nikula shapers= [NET] 4308e52347bdSJani Nikula Maximal number of shapers. 4309e52347bdSJani Nikula 4310e52347bdSJani Nikula simeth= [IA-64] 4311e52347bdSJani Nikula simscsi= 4312e52347bdSJani Nikula 4313e52347bdSJani Nikula slram= [HW,MTD] 4314e52347bdSJani Nikula 4315e52347bdSJani Nikula slab_nomerge [MM] 4316e52347bdSJani Nikula Disable merging of slabs with similar size. May be 4317e52347bdSJani Nikula necessary if there is some reason to distinguish 43187660a6fdSKees Cook allocs to different slabs, especially in hardened 43197660a6fdSKees Cook environments where the risk of heap overflows and 43207660a6fdSKees Cook layout control by attackers can usually be 43217660a6fdSKees Cook frustrated by disabling merging. This will reduce 43227660a6fdSKees Cook most of the exposure of a heap attack to a single 43237660a6fdSKees Cook cache (risks via metadata attacks are mostly 43247660a6fdSKees Cook unchanged). Debug options disable merging on their 43257660a6fdSKees Cook own. 4326ad56b738SMike Rapoport For more information see Documentation/vm/slub.rst. 4327e52347bdSJani Nikula 4328e52347bdSJani Nikula slab_max_order= [MM, SLAB] 4329e52347bdSJani Nikula Determines the maximum allowed order for slabs. 4330e52347bdSJani Nikula A high setting may cause OOMs due to memory 4331e52347bdSJani Nikula fragmentation. Defaults to 1 for systems with 4332e52347bdSJani Nikula more than 32MB of RAM, 0 otherwise. 4333e52347bdSJani Nikula 4334e52347bdSJani Nikula slub_debug[=options[,slabs]] [MM, SLUB] 4335e52347bdSJani Nikula Enabling slub_debug allows one to determine the 4336e52347bdSJani Nikula culprit if slab objects become corrupted. Enabling 4337e52347bdSJani Nikula slub_debug can create guard zones around objects and 4338e52347bdSJani Nikula may poison objects when not in use. Also tracks the 4339e52347bdSJani Nikula last alloc / free. For more information see 4340ad56b738SMike Rapoport Documentation/vm/slub.rst. 4341e52347bdSJani Nikula 43421663f26dSTejun Heo slub_memcg_sysfs= [MM, SLUB] 43431663f26dSTejun Heo Determines whether to enable sysfs directories for 43441663f26dSTejun Heo memory cgroup sub-caches. 1 to enable, 0 to disable. 43451663f26dSTejun Heo The default is determined by CONFIG_SLUB_MEMCG_SYSFS_ON. 43461663f26dSTejun Heo Enabling this can lead to a very high number of debug 43471663f26dSTejun Heo directories and files being created under 43481663f26dSTejun Heo /sys/kernel/slub. 43491663f26dSTejun Heo 4350e52347bdSJani Nikula slub_max_order= [MM, SLUB] 4351e52347bdSJani Nikula Determines the maximum allowed order for slabs. 4352e52347bdSJani Nikula A high setting may cause OOMs due to memory 4353e52347bdSJani Nikula fragmentation. For more information see 4354ad56b738SMike Rapoport Documentation/vm/slub.rst. 4355e52347bdSJani Nikula 4356e52347bdSJani Nikula slub_min_objects= [MM, SLUB] 4357e52347bdSJani Nikula The minimum number of objects per slab. SLUB will 4358e52347bdSJani Nikula increase the slab order up to slub_max_order to 4359e52347bdSJani Nikula generate a sufficiently large slab able to contain 4360e52347bdSJani Nikula the number of objects indicated. The higher the number 4361e52347bdSJani Nikula of objects the smaller the overhead of tracking slabs 4362e52347bdSJani Nikula and the less frequently locks need to be acquired. 4363ad56b738SMike Rapoport For more information see Documentation/vm/slub.rst. 4364e52347bdSJani Nikula 4365e52347bdSJani Nikula slub_min_order= [MM, SLUB] 4366e52347bdSJani Nikula Determines the minimum page order for slabs. Must be 4367e52347bdSJani Nikula lower than slub_max_order. 4368ad56b738SMike Rapoport For more information see Documentation/vm/slub.rst. 4369e52347bdSJani Nikula 4370e52347bdSJani Nikula slub_nomerge [MM, SLUB] 4371e52347bdSJani Nikula Same with slab_nomerge. This is supported for legacy. 4372e52347bdSJani Nikula See slab_nomerge for more information. 4373e52347bdSJani Nikula 4374e52347bdSJani Nikula smart2= [HW] 4375e52347bdSJani Nikula Format: <io1>[,<io2>[,...,<io8>]] 4376e52347bdSJani Nikula 4377e52347bdSJani Nikula smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices 4378e52347bdSJani Nikula smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port 4379e52347bdSJani Nikula smsc-ircc2.ircc_sir= [HW] SIR base I/O port 4380e52347bdSJani Nikula smsc-ircc2.ircc_fir= [HW] FIR base I/O port 4381e52347bdSJani Nikula smsc-ircc2.ircc_irq= [HW] IRQ line 4382e52347bdSJani Nikula smsc-ircc2.ircc_dma= [HW] DMA channel 4383e52347bdSJani Nikula smsc-ircc2.ircc_transceiver= [HW] Transceiver type: 4384e52347bdSJani Nikula 0: Toshiba Satellite 1800 (GP data pin select) 4385e52347bdSJani Nikula 1: Fast pin select (default) 4386e52347bdSJani Nikula 2: ATC IRMode 4387e52347bdSJani Nikula 4388e52347bdSJani Nikula smt [KNL,S390] Set the maximum number of threads (logical 4389e52347bdSJani Nikula CPUs) to use per physical CPU on systems capable of 4390e52347bdSJani Nikula symmetric multithreading (SMT). Will be capped to the 4391e52347bdSJani Nikula actual hardware limit. 4392e52347bdSJani Nikula Format: <integer> 4393e52347bdSJani Nikula Default: -1 (no limit) 4394e52347bdSJani Nikula 4395e52347bdSJani Nikula softlockup_panic= 4396e52347bdSJani Nikula [KNL] Should the soft-lockup detector generate panics. 4397e52347bdSJani Nikula Format: <integer> 4398e52347bdSJani Nikula 43993ce62385SBorislav Petkov A nonzero value instructs the soft-lockup detector 44003ce62385SBorislav Petkov to panic the machine when a soft-lockup occurs. This 44013ce62385SBorislav Petkov is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC 44023ce62385SBorislav Petkov which is the respective build-time switch to that 44033ce62385SBorislav Petkov functionality. 44043ce62385SBorislav Petkov 4405e52347bdSJani Nikula softlockup_all_cpu_backtrace= 4406e52347bdSJani Nikula [KNL] Should the soft-lockup detector generate 4407e52347bdSJani Nikula backtraces on all cpus. 4408e52347bdSJani Nikula Format: <integer> 4409e52347bdSJani Nikula 4410e52347bdSJani Nikula sonypi.*= [HW] Sony Programmable I/O Control Device driver 44119e1cbedeSMauro Carvalho Chehab See Documentation/admin-guide/laptops/sonypi.rst 4412e52347bdSJani Nikula 4413da285121SDavid Woodhouse spectre_v2= [X86] Control mitigation of Spectre variant 2 4414da285121SDavid Woodhouse (indirect branch speculation) vulnerability. 4415fa1202efSThomas Gleixner The default operation protects the kernel from 4416fa1202efSThomas Gleixner user space attacks. 4417da285121SDavid Woodhouse 4418fa1202efSThomas Gleixner on - unconditionally enable, implies 4419fa1202efSThomas Gleixner spectre_v2_user=on 4420fa1202efSThomas Gleixner off - unconditionally disable, implies 4421fa1202efSThomas Gleixner spectre_v2_user=off 4422da285121SDavid Woodhouse auto - kernel detects whether your CPU model is 4423da285121SDavid Woodhouse vulnerable 4424da285121SDavid Woodhouse 4425da285121SDavid Woodhouse Selecting 'on' will, and 'auto' may, choose a 4426da285121SDavid Woodhouse mitigation method at run time according to the 4427da285121SDavid Woodhouse CPU, the available microcode, the setting of the 4428da285121SDavid Woodhouse CONFIG_RETPOLINE configuration option, and the 4429da285121SDavid Woodhouse compiler with which the kernel was built. 4430da285121SDavid Woodhouse 4431fa1202efSThomas Gleixner Selecting 'on' will also enable the mitigation 4432fa1202efSThomas Gleixner against user space to user space task attacks. 4433fa1202efSThomas Gleixner 4434fa1202efSThomas Gleixner Selecting 'off' will disable both the kernel and 4435fa1202efSThomas Gleixner the user space protections. 4436fa1202efSThomas Gleixner 4437da285121SDavid Woodhouse Specific mitigations can also be selected manually: 4438da285121SDavid Woodhouse 4439da285121SDavid Woodhouse retpoline - replace indirect branches 4440da285121SDavid Woodhouse retpoline,generic - google's original retpoline 4441da285121SDavid Woodhouse retpoline,amd - AMD-specific minimal thunk 4442da285121SDavid Woodhouse 4443da285121SDavid Woodhouse Not specifying this option is equivalent to 4444da285121SDavid Woodhouse spectre_v2=auto. 4445da285121SDavid Woodhouse 4446fa1202efSThomas Gleixner spectre_v2_user= 4447fa1202efSThomas Gleixner [X86] Control mitigation of Spectre variant 2 4448fa1202efSThomas Gleixner (indirect branch speculation) vulnerability between 4449fa1202efSThomas Gleixner user space tasks 4450fa1202efSThomas Gleixner 4451fa1202efSThomas Gleixner on - Unconditionally enable mitigations. Is 4452fa1202efSThomas Gleixner enforced by spectre_v2=on 4453fa1202efSThomas Gleixner 4454fa1202efSThomas Gleixner off - Unconditionally disable mitigations. Is 4455fa1202efSThomas Gleixner enforced by spectre_v2=off 4456fa1202efSThomas Gleixner 44577cc765a6SThomas Gleixner prctl - Indirect branch speculation is enabled, 44587cc765a6SThomas Gleixner but mitigation can be enabled via prctl 44597cc765a6SThomas Gleixner per thread. The mitigation control state 44607cc765a6SThomas Gleixner is inherited on fork. 44617cc765a6SThomas Gleixner 446255a97402SThomas Gleixner prctl,ibpb 446355a97402SThomas Gleixner - Like "prctl" above, but only STIBP is 446455a97402SThomas Gleixner controlled per thread. IBPB is issued 446555a97402SThomas Gleixner always when switching between different user 446655a97402SThomas Gleixner space processes. 446755a97402SThomas Gleixner 44686b3e64c2SThomas Gleixner seccomp 44696b3e64c2SThomas Gleixner - Same as "prctl" above, but all seccomp 44706b3e64c2SThomas Gleixner threads will enable the mitigation unless 44716b3e64c2SThomas Gleixner they explicitly opt out. 44726b3e64c2SThomas Gleixner 447355a97402SThomas Gleixner seccomp,ibpb 447455a97402SThomas Gleixner - Like "seccomp" above, but only STIBP is 447555a97402SThomas Gleixner controlled per thread. IBPB is issued 447655a97402SThomas Gleixner always when switching between different 447755a97402SThomas Gleixner user space processes. 447855a97402SThomas Gleixner 4479fa1202efSThomas Gleixner auto - Kernel selects the mitigation depending on 4480fa1202efSThomas Gleixner the available CPU features and vulnerability. 44816b3e64c2SThomas Gleixner 44826b3e64c2SThomas Gleixner Default mitigation: 44836b3e64c2SThomas Gleixner If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl" 4484fa1202efSThomas Gleixner 4485fa1202efSThomas Gleixner Not specifying this option is equivalent to 4486fa1202efSThomas Gleixner spectre_v2_user=auto. 4487fa1202efSThomas Gleixner 448824f7fc83SKonrad Rzeszutek Wilk spec_store_bypass_disable= 448924f7fc83SKonrad Rzeszutek Wilk [HW] Control Speculative Store Bypass (SSB) Disable mitigation 449024f7fc83SKonrad Rzeszutek Wilk (Speculative Store Bypass vulnerability) 449124f7fc83SKonrad Rzeszutek Wilk 449224f7fc83SKonrad Rzeszutek Wilk Certain CPUs are vulnerable to an exploit against a 449324f7fc83SKonrad Rzeszutek Wilk a common industry wide performance optimization known 449424f7fc83SKonrad Rzeszutek Wilk as "Speculative Store Bypass" in which recent stores 449524f7fc83SKonrad Rzeszutek Wilk to the same memory location may not be observed by 449624f7fc83SKonrad Rzeszutek Wilk later loads during speculative execution. The idea 449724f7fc83SKonrad Rzeszutek Wilk is that such stores are unlikely and that they can 449824f7fc83SKonrad Rzeszutek Wilk be detected prior to instruction retirement at the 449924f7fc83SKonrad Rzeszutek Wilk end of a particular speculation execution window. 450024f7fc83SKonrad Rzeszutek Wilk 450124f7fc83SKonrad Rzeszutek Wilk In vulnerable processors, the speculatively forwarded 450224f7fc83SKonrad Rzeszutek Wilk store can be used in a cache side channel attack, for 450324f7fc83SKonrad Rzeszutek Wilk example to read memory to which the attacker does not 450424f7fc83SKonrad Rzeszutek Wilk directly have access (e.g. inside sandboxed code). 450524f7fc83SKonrad Rzeszutek Wilk 450624f7fc83SKonrad Rzeszutek Wilk This parameter controls whether the Speculative Store 450724f7fc83SKonrad Rzeszutek Wilk Bypass optimization is used. 450824f7fc83SKonrad Rzeszutek Wilk 45096b4c1360SMichael Ellerman On x86 the options are: 45106b4c1360SMichael Ellerman 451124f7fc83SKonrad Rzeszutek Wilk on - Unconditionally disable Speculative Store Bypass 451224f7fc83SKonrad Rzeszutek Wilk off - Unconditionally enable Speculative Store Bypass 451324f7fc83SKonrad Rzeszutek Wilk auto - Kernel detects whether the CPU model contains an 451424f7fc83SKonrad Rzeszutek Wilk implementation of Speculative Store Bypass and 4515f21b53b2SKees Cook picks the most appropriate mitigation. If the 4516f21b53b2SKees Cook CPU is not vulnerable, "off" is selected. If the 4517f21b53b2SKees Cook CPU is vulnerable the default mitigation is 4518f21b53b2SKees Cook architecture and Kconfig dependent. See below. 4519a73ec77eSThomas Gleixner prctl - Control Speculative Store Bypass per thread 4520a73ec77eSThomas Gleixner via prctl. Speculative Store Bypass is enabled 4521a73ec77eSThomas Gleixner for a process by default. The state of the control 4522a73ec77eSThomas Gleixner is inherited on fork. 4523f21b53b2SKees Cook seccomp - Same as "prctl" above, but all seccomp threads 4524f21b53b2SKees Cook will disable SSB unless they explicitly opt out. 452524f7fc83SKonrad Rzeszutek Wilk 4526f21b53b2SKees Cook Default mitigations: 4527f21b53b2SKees Cook X86: If CONFIG_SECCOMP=y "seccomp", otherwise "prctl" 4528f21b53b2SKees Cook 45296b4c1360SMichael Ellerman On powerpc the options are: 45306b4c1360SMichael Ellerman 45316b4c1360SMichael Ellerman on,auto - On Power8 and Power9 insert a store-forwarding 45326b4c1360SMichael Ellerman barrier on kernel entry and exit. On Power7 45336b4c1360SMichael Ellerman perform a software flush on kernel entry and 45346b4c1360SMichael Ellerman exit. 45356b4c1360SMichael Ellerman off - No action. 45366b4c1360SMichael Ellerman 45376b4c1360SMichael Ellerman Not specifying this option is equivalent to 45386b4c1360SMichael Ellerman spec_store_bypass_disable=auto. 45396b4c1360SMichael Ellerman 4540e52347bdSJani Nikula spia_io_base= [HW,MTD] 4541e52347bdSJani Nikula spia_fio_base= 4542e52347bdSJani Nikula spia_pedr= 4543e52347bdSJani Nikula spia_peddr= 4544e52347bdSJani Nikula 4545c350c008SPaul E. McKenney srcutree.counter_wrap_check [KNL] 4546c350c008SPaul E. McKenney Specifies how frequently to check for 4547c350c008SPaul E. McKenney grace-period sequence counter wrap for the 4548c350c008SPaul E. McKenney srcu_data structure's ->srcu_gp_seq_needed field. 4549c350c008SPaul E. McKenney The greater the number of bits set in this kernel 4550c350c008SPaul E. McKenney parameter, the less frequently counter wrap will 4551c350c008SPaul E. McKenney be checked for. Note that the bottom two bits 4552c350c008SPaul E. McKenney are ignored. 4553c350c008SPaul E. McKenney 455422607d66SPaul E. McKenney srcutree.exp_holdoff [KNL] 455522607d66SPaul E. McKenney Specifies how many nanoseconds must elapse 455622607d66SPaul E. McKenney since the end of the last SRCU grace period for 455722607d66SPaul E. McKenney a given srcu_struct until the next normal SRCU 455822607d66SPaul E. McKenney grace period will be considered for automatic 455922607d66SPaul E. McKenney expediting. Set to zero to disable automatic 456022607d66SPaul E. McKenney expediting. 456122607d66SPaul E. McKenney 4562a43ae4dfSMarc Zyngier ssbd= [ARM64,HW] 4563a43ae4dfSMarc Zyngier Speculative Store Bypass Disable control 4564a43ae4dfSMarc Zyngier 4565a43ae4dfSMarc Zyngier On CPUs that are vulnerable to the Speculative 4566a43ae4dfSMarc Zyngier Store Bypass vulnerability and offer a 4567a43ae4dfSMarc Zyngier firmware based mitigation, this parameter 4568a43ae4dfSMarc Zyngier indicates how the mitigation should be used: 4569a43ae4dfSMarc Zyngier 4570a43ae4dfSMarc Zyngier force-on: Unconditionally enable mitigation for 4571a43ae4dfSMarc Zyngier for both kernel and userspace 4572a43ae4dfSMarc Zyngier force-off: Unconditionally disable mitigation for 4573a43ae4dfSMarc Zyngier for both kernel and userspace 4574a43ae4dfSMarc Zyngier kernel: Always enable mitigation in the 4575a43ae4dfSMarc Zyngier kernel, and offer a prctl interface 4576a43ae4dfSMarc Zyngier to allow userspace to register its 4577a43ae4dfSMarc Zyngier interest in being mitigated too. 4578a43ae4dfSMarc Zyngier 45791be7107fSHugh Dickins stack_guard_gap= [MM] 45801be7107fSHugh Dickins override the default stack gap protection. The value 45811be7107fSHugh Dickins is in page units and it defines how many pages prior 45821be7107fSHugh Dickins to (for stacks growing down) resp. after (for stacks 45831be7107fSHugh Dickins growing up) the main stack are reserved for no other 45841be7107fSHugh Dickins mapping. Default value is 256 pages. 45851be7107fSHugh Dickins 4586e52347bdSJani Nikula stacktrace [FTRACE] 4587e52347bdSJani Nikula Enabled the stack tracer on boot up. 4588e52347bdSJani Nikula 4589e52347bdSJani Nikula stacktrace_filter=[function-list] 4590e52347bdSJani Nikula [FTRACE] Limit the functions that the stack tracer 4591e52347bdSJani Nikula will trace at boot up. function-list is a comma separated 4592e52347bdSJani Nikula list of functions. This list can be changed at run 4593e52347bdSJani Nikula time by the stack_trace_filter file in the debugfs 4594e52347bdSJani Nikula tracing directory. Note, this enables stack tracing 4595e52347bdSJani Nikula and the stacktrace above is not needed. 4596e52347bdSJani Nikula 4597e52347bdSJani Nikula sti= [PARISC,HW] 4598e52347bdSJani Nikula Format: <num> 4599e52347bdSJani Nikula Set the STI (builtin display/keyboard on the HP-PARISC 4600e52347bdSJani Nikula machines) console (graphic card) which should be used 4601e52347bdSJani Nikula as the initial boot-console. 4602e52347bdSJani Nikula See also comment in drivers/video/console/sticore.c. 4603e52347bdSJani Nikula 4604e52347bdSJani Nikula sti_font= [HW] 4605e52347bdSJani Nikula See comment in drivers/video/console/sticore.c. 4606e52347bdSJani Nikula 4607e52347bdSJani Nikula stifb= [HW] 4608e52347bdSJani Nikula Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] 4609e52347bdSJani Nikula 4610e52347bdSJani Nikula sunrpc.min_resvport= 4611e52347bdSJani Nikula sunrpc.max_resvport= 4612e52347bdSJani Nikula [NFS,SUNRPC] 4613e52347bdSJani Nikula SunRPC servers often require that client requests 4614e52347bdSJani Nikula originate from a privileged port (i.e. a port in the 4615e52347bdSJani Nikula range 0 < portnr < 1024). 4616e52347bdSJani Nikula An administrator who wishes to reserve some of these 4617e52347bdSJani Nikula ports for other uses may adjust the range that the 4618e52347bdSJani Nikula kernel's sunrpc client considers to be privileged 4619e52347bdSJani Nikula using these two parameters to set the minimum and 4620e52347bdSJani Nikula maximum port values. 4621e52347bdSJani Nikula 4622e52347bdSJani Nikula sunrpc.svc_rpc_per_connection_limit= 4623e52347bdSJani Nikula [NFS,SUNRPC] 4624e52347bdSJani Nikula Limit the number of requests that the server will 4625e52347bdSJani Nikula process in parallel from a single connection. 4626e52347bdSJani Nikula The default value is 0 (no limit). 4627e52347bdSJani Nikula 4628e52347bdSJani Nikula sunrpc.pool_mode= 4629e52347bdSJani Nikula [NFS] 4630e52347bdSJani Nikula Control how the NFS server code allocates CPUs to 4631e52347bdSJani Nikula service thread pools. Depending on how many NICs 4632e52347bdSJani Nikula you have and where their interrupts are bound, this 4633e52347bdSJani Nikula option will affect which CPUs will do NFS serving. 4634e52347bdSJani Nikula Note: this parameter cannot be changed while the 4635e52347bdSJani Nikula NFS server is running. 4636e52347bdSJani Nikula 4637e52347bdSJani Nikula auto the server chooses an appropriate mode 4638e52347bdSJani Nikula automatically using heuristics 4639e52347bdSJani Nikula global a single global pool contains all CPUs 4640e52347bdSJani Nikula percpu one pool for each CPU 4641e52347bdSJani Nikula pernode one pool for each NUMA node (equivalent 4642e52347bdSJani Nikula to global on non-NUMA machines) 4643e52347bdSJani Nikula 4644e52347bdSJani Nikula sunrpc.tcp_slot_table_entries= 4645e52347bdSJani Nikula sunrpc.udp_slot_table_entries= 4646e52347bdSJani Nikula [NFS,SUNRPC] 4647e52347bdSJani Nikula Sets the upper limit on the number of simultaneous 4648e52347bdSJani Nikula RPC calls that can be sent from the client to a 4649e52347bdSJani Nikula server. Increasing these values may allow you to 4650e52347bdSJani Nikula improve throughput, but will also increase the 4651e52347bdSJani Nikula amount of memory reserved for use by the client. 4652e52347bdSJani Nikula 4653e52347bdSJani Nikula suspend.pm_test_delay= 4654e52347bdSJani Nikula [SUSPEND] 4655e52347bdSJani Nikula Sets the number of seconds to remain in a suspend test 4656e52347bdSJani Nikula mode before resuming the system (see 4657e52347bdSJani Nikula /sys/power/pm_test). Only available when CONFIG_PM_DEBUG 4658e52347bdSJani Nikula is set. Default value is 5. 4659e52347bdSJani Nikula 46606a9c930bSRam Pai svm= [PPC] 46616a9c930bSRam Pai Format: { on | off | y | n | 1 | 0 } 46626a9c930bSRam Pai This parameter controls use of the Protected 46636a9c930bSRam Pai Execution Facility on pSeries. 46646a9c930bSRam Pai 4665e52347bdSJani Nikula swapaccount=[0|1] 4666e52347bdSJani Nikula [KNL] Enable accounting of swap in memory resource 4667e52347bdSJani Nikula controller if no parameter or 1 is given or disable 4668da82c92fSMauro Carvalho Chehab it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst) 4669e52347bdSJani Nikula 4670e52347bdSJani Nikula swiotlb= [ARM,IA-64,PPC,MIPS,X86] 4671fff5d992SGeert Uytterhoeven Format: { <int> | force | noforce } 4672e52347bdSJani Nikula <int> -- Number of I/O TLB slabs 4673e52347bdSJani Nikula force -- force using of bounce buffers even if they 4674e52347bdSJani Nikula wouldn't be automatically used by the kernel 4675fff5d992SGeert Uytterhoeven noforce -- Never use bounce buffers (for debugging) 4676e52347bdSJani Nikula 4677e52347bdSJani Nikula switches= [HW,M68k] 4678e52347bdSJani Nikula 4679e52347bdSJani Nikula sysfs.deprecated=0|1 [KNL] 4680e52347bdSJani Nikula Enable/disable old style sysfs layout for old udev 4681e52347bdSJani Nikula on older distributions. When this option is enabled 4682e52347bdSJani Nikula very new udev will not work anymore. When this option 4683e52347bdSJani Nikula is disabled (or CONFIG_SYSFS_DEPRECATED not compiled) 4684e52347bdSJani Nikula in older udev will not work anymore. 4685e52347bdSJani Nikula Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in 4686e52347bdSJani Nikula the kernel configuration. 4687e52347bdSJani Nikula 4688e52347bdSJani Nikula sysrq_always_enabled 4689e52347bdSJani Nikula [KNL] 4690e52347bdSJani Nikula Ignore sysrq setting - this boot parameter will 4691e52347bdSJani Nikula neutralize any effect of /proc/sys/kernel/sysrq. 4692e52347bdSJani Nikula Useful for debugging. 4693e52347bdSJani Nikula 4694e52347bdSJani Nikula tcpmhash_entries= [KNL,NET] 4695e52347bdSJani Nikula Set the number of tcp_metrics_hash slots. 4696e52347bdSJani Nikula Default value is 8192 or 16384 depending on total 4697e52347bdSJani Nikula ram pages. This is used to specify the TCP metrics 4698e52347bdSJani Nikula cache size. See Documentation/networking/ip-sysctl.txt 4699e52347bdSJani Nikula "tcp_no_metrics_save" section for more details. 4700e52347bdSJani Nikula 4701e52347bdSJani Nikula tdfx= [HW,DRM] 4702e52347bdSJani Nikula 4703e52347bdSJani Nikula test_suspend= [SUSPEND][,N] 4704e52347bdSJani Nikula Specify "mem" (for Suspend-to-RAM) or "standby" (for 4705e52347bdSJani Nikula standby suspend) or "freeze" (for suspend type freeze) 4706e52347bdSJani Nikula as the system sleep state during system startup with 4707e52347bdSJani Nikula the optional capability to repeat N number of times. 4708e52347bdSJani Nikula The system is woken from this state using a 4709e52347bdSJani Nikula wakeup-capable RTC alarm. 4710e52347bdSJani Nikula 4711e52347bdSJani Nikula thash_entries= [KNL,NET] 4712e52347bdSJani Nikula Set number of hash buckets for TCP connection 4713e52347bdSJani Nikula 4714e52347bdSJani Nikula thermal.act= [HW,ACPI] 4715e52347bdSJani Nikula -1: disable all active trip points in all thermal zones 4716e52347bdSJani Nikula <degrees C>: override all lowest active trip points 4717e52347bdSJani Nikula 4718e52347bdSJani Nikula thermal.crt= [HW,ACPI] 4719e52347bdSJani Nikula -1: disable all critical trip points in all thermal zones 4720e52347bdSJani Nikula <degrees C>: override all critical trip points 4721e52347bdSJani Nikula 4722e52347bdSJani Nikula thermal.nocrt= [HW,ACPI] 4723e52347bdSJani Nikula Set to disable actions on ACPI thermal zone 4724e52347bdSJani Nikula critical and hot trip points. 4725e52347bdSJani Nikula 4726e52347bdSJani Nikula thermal.off= [HW,ACPI] 4727e52347bdSJani Nikula 1: disable ACPI thermal control 4728e52347bdSJani Nikula 4729e52347bdSJani Nikula thermal.psv= [HW,ACPI] 4730e52347bdSJani Nikula -1: disable all passive trip points 4731e52347bdSJani Nikula <degrees C>: override all passive trip points to this 4732e52347bdSJani Nikula value 4733e52347bdSJani Nikula 4734e52347bdSJani Nikula thermal.tzp= [HW,ACPI] 4735e52347bdSJani Nikula Specify global default ACPI thermal zone polling rate 4736e52347bdSJani Nikula <deci-seconds>: poll all this frequency 4737e52347bdSJani Nikula 0: no polling (default) 4738e52347bdSJani Nikula 4739e52347bdSJani Nikula threadirqs [KNL] 4740e52347bdSJani Nikula Force threading of all interrupt handlers except those 4741e52347bdSJani Nikula marked explicitly IRQF_NO_THREAD. 4742e52347bdSJani Nikula 4743e52347bdSJani Nikula topology= [S390] 4744e52347bdSJani Nikula Format: {off | on} 4745e52347bdSJani Nikula Specify if the kernel should make use of the cpu 4746e52347bdSJani Nikula topology information if the hardware supports this. 4747e52347bdSJani Nikula The scheduler will make use of this information and 4748e52347bdSJani Nikula e.g. base its process migration decisions on it. 4749e52347bdSJani Nikula Default is on. 4750e52347bdSJani Nikula 4751e52347bdSJani Nikula topology_updates= [KNL, PPC, NUMA] 4752e52347bdSJani Nikula Format: {off} 4753e52347bdSJani Nikula Specify if the kernel should ignore (off) 4754e52347bdSJani Nikula topology updates sent by the hypervisor to this 4755e52347bdSJani Nikula LPAR. 4756e52347bdSJani Nikula 4757e52347bdSJani Nikula tp720= [HW,PS2] 4758e52347bdSJani Nikula 4759e52347bdSJani Nikula tpm_suspend_pcr=[HW,TPM] 4760e52347bdSJani Nikula Format: integer pcr id 4761e52347bdSJani Nikula Specify that at suspend time, the tpm driver 4762e52347bdSJani Nikula should extend the specified pcr with zeros, 4763e52347bdSJani Nikula as a workaround for some chips which fail to 4764e52347bdSJani Nikula flush the last written pcr on TPM_SaveState. 4765e52347bdSJani Nikula This will guarantee that all the other pcrs 4766e52347bdSJani Nikula are saved. 4767e52347bdSJani Nikula 4768e52347bdSJani Nikula trace_buf_size=nn[KMG] 4769e52347bdSJani Nikula [FTRACE] will set tracing buffer size on each cpu. 4770e52347bdSJani Nikula 4771e52347bdSJani Nikula trace_event=[event-list] 4772e52347bdSJani Nikula [FTRACE] Set and start specified trace events in order 4773e52347bdSJani Nikula to facilitate early boot debugging. The event-list is a 4774e52347bdSJani Nikula comma separated list of trace events to enable. See 47755fb94e9cSMauro Carvalho Chehab also Documentation/trace/events.rst 4776e52347bdSJani Nikula 4777e52347bdSJani Nikula trace_options=[option-list] 4778e52347bdSJani Nikula [FTRACE] Enable or disable tracer options at boot. 4779e52347bdSJani Nikula The option-list is a comma delimited list of options 4780e52347bdSJani Nikula that can be enabled or disabled just as if you were 4781e52347bdSJani Nikula to echo the option name into 4782e52347bdSJani Nikula 4783e52347bdSJani Nikula /sys/kernel/debug/tracing/trace_options 4784e52347bdSJani Nikula 4785e52347bdSJani Nikula For example, to enable stacktrace option (to dump the 4786e52347bdSJani Nikula stack trace of each event), add to the command line: 4787e52347bdSJani Nikula 4788e52347bdSJani Nikula trace_options=stacktrace 4789e52347bdSJani Nikula 47905fb94e9cSMauro Carvalho Chehab See also Documentation/trace/ftrace.rst "trace options" 4791e52347bdSJani Nikula section. 4792e52347bdSJani Nikula 4793e52347bdSJani Nikula tp_printk[FTRACE] 4794e52347bdSJani Nikula Have the tracepoints sent to printk as well as the 4795e52347bdSJani Nikula tracing ring buffer. This is useful for early boot up 4796e52347bdSJani Nikula where the system hangs or reboots and does not give the 4797e52347bdSJani Nikula option for reading the tracing buffer or performing a 4798e52347bdSJani Nikula ftrace_dump_on_oops. 4799e52347bdSJani Nikula 4800e52347bdSJani Nikula To turn off having tracepoints sent to printk, 4801e52347bdSJani Nikula echo 0 > /proc/sys/kernel/tracepoint_printk 4802e52347bdSJani Nikula Note, echoing 1 into this file without the 4803e52347bdSJani Nikula tracepoint_printk kernel cmdline option has no effect. 4804e52347bdSJani Nikula 4805e52347bdSJani Nikula ** CAUTION ** 4806e52347bdSJani Nikula 4807e52347bdSJani Nikula Having tracepoints sent to printk() and activating high 4808e52347bdSJani Nikula frequency tracepoints such as irq or sched, can cause 4809e52347bdSJani Nikula the system to live lock. 4810e52347bdSJani Nikula 4811e52347bdSJani Nikula traceoff_on_warning 4812e52347bdSJani Nikula [FTRACE] enable this option to disable tracing when a 4813e52347bdSJani Nikula warning is hit. This turns off "tracing_on". Tracing can 4814e52347bdSJani Nikula be enabled again by echoing '1' into the "tracing_on" 4815e52347bdSJani Nikula file located in /sys/kernel/debug/tracing/ 4816e52347bdSJani Nikula 4817e52347bdSJani Nikula This option is useful, as it disables the trace before 4818e52347bdSJani Nikula the WARNING dump is called, which prevents the trace to 4819e52347bdSJani Nikula be filled with content caused by the warning output. 4820e52347bdSJani Nikula 4821e52347bdSJani Nikula This option can also be set at run time via the sysctl 4822e52347bdSJani Nikula option: kernel/traceoff_on_warning 4823e52347bdSJani Nikula 4824e52347bdSJani Nikula transparent_hugepage= 4825e52347bdSJani Nikula [KNL] 4826e52347bdSJani Nikula Format: [always|madvise|never] 4827e52347bdSJani Nikula Can be used to control the default behavior of the system 4828e52347bdSJani Nikula with respect to transparent hugepages. 482945c9a74fSMike Rapoport See Documentation/admin-guide/mm/transhuge.rst 483045c9a74fSMike Rapoport for more details. 4831e52347bdSJani Nikula 4832e52347bdSJani Nikula tsc= Disable clocksource stability checks for TSC. 4833e52347bdSJani Nikula Format: <string> 4834e52347bdSJani Nikula [x86] reliable: mark tsc clocksource as reliable, this 4835e52347bdSJani Nikula disables clocksource verification at runtime, as well 4836e52347bdSJani Nikula as the stability checks done at bootup. Used to enable 4837e52347bdSJani Nikula high-resolution timer mode on older hardware, and in 4838e52347bdSJani Nikula virtualized environment. 4839e52347bdSJani Nikula [x86] noirqtime: Do not use TSC to do irq accounting. 4840e52347bdSJani Nikula Used to run time disable IRQ_TIME_ACCOUNTING on any 4841e52347bdSJani Nikula platforms where RDTSC is slow and this accounting 4842e52347bdSJani Nikula can add overhead. 48436be53520SDou Liyang [x86] unstable: mark the TSC clocksource as unstable, this 48446be53520SDou Liyang marks the TSC unconditionally unstable at bootup and 48456be53520SDou Liyang avoids any further wobbles once the TSC watchdog notices. 48460f0b7e1cSJuri Lelli [x86] nowatchdog: disable clocksource watchdog. Used 48470f0b7e1cSJuri Lelli in situations with strict latency requirements (where 48480f0b7e1cSJuri Lelli interruptions from clocksource watchdog are not 48490f0b7e1cSJuri Lelli acceptable). 4850e52347bdSJani Nikula 485195c5824fSPawan Gupta tsx= [X86] Control Transactional Synchronization 485295c5824fSPawan Gupta Extensions (TSX) feature in Intel processors that 485395c5824fSPawan Gupta support TSX control. 485495c5824fSPawan Gupta 485595c5824fSPawan Gupta This parameter controls the TSX feature. The options are: 485695c5824fSPawan Gupta 485795c5824fSPawan Gupta on - Enable TSX on the system. Although there are 485895c5824fSPawan Gupta mitigations for all known security vulnerabilities, 485995c5824fSPawan Gupta TSX has been known to be an accelerator for 486095c5824fSPawan Gupta several previous speculation-related CVEs, and 486195c5824fSPawan Gupta so there may be unknown security risks associated 486295c5824fSPawan Gupta with leaving it enabled. 486395c5824fSPawan Gupta 486495c5824fSPawan Gupta off - Disable TSX on the system. (Note that this 486595c5824fSPawan Gupta option takes effect only on newer CPUs which are 486695c5824fSPawan Gupta not vulnerable to MDS, i.e., have 486795c5824fSPawan Gupta MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1 and which get 486895c5824fSPawan Gupta the new IA32_TSX_CTRL MSR through a microcode 486995c5824fSPawan Gupta update. This new MSR allows for the reliable 487095c5824fSPawan Gupta deactivation of the TSX functionality.) 487195c5824fSPawan Gupta 487295c5824fSPawan Gupta Not specifying this option is equivalent to tsx=off. 487395c5824fSPawan Gupta 487495c5824fSPawan Gupta See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst 487595c5824fSPawan Gupta for more details. 487695c5824fSPawan Gupta 4877e52347bdSJani Nikula turbografx.map[2|3]= [HW,JOY] 4878e52347bdSJani Nikula TurboGraFX parallel port interface 4879e52347bdSJani Nikula Format: 4880e52347bdSJani Nikula <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> 48811752118dSTom Saeger See also Documentation/input/devices/joystick-parport.rst 4882e52347bdSJani Nikula 4883e52347bdSJani Nikula udbg-immortal [PPC] When debugging early kernel crashes that 4884e52347bdSJani Nikula happen after console_init() and before a proper 4885e52347bdSJani Nikula console driver takes over, this boot options might 4886e52347bdSJani Nikula help "seeing" what's going on. 4887e52347bdSJani Nikula 4888e52347bdSJani Nikula uhash_entries= [KNL,NET] 4889e52347bdSJani Nikula Set number of hash buckets for UDP/UDP-Lite connections 4890e52347bdSJani Nikula 4891e52347bdSJani Nikula uhci-hcd.ignore_oc= 4892e52347bdSJani Nikula [USB] Ignore overcurrent events (default N). 4893e52347bdSJani Nikula Some badly-designed motherboards generate lots of 4894e52347bdSJani Nikula bogus events, for ports that aren't wired to 4895e52347bdSJani Nikula anything. Set this parameter to avoid log spamming. 4896e52347bdSJani Nikula Note that genuine overcurrent events won't be 4897e52347bdSJani Nikula reported either. 4898e52347bdSJani Nikula 4899e52347bdSJani Nikula unknown_nmi_panic 4900e52347bdSJani Nikula [X86] Cause panic on unknown NMI. 4901e52347bdSJani Nikula 4902e52347bdSJani Nikula usbcore.authorized_default= 4903e52347bdSJani Nikula [USB] Default USB device authorization: 4904e52347bdSJani Nikula (default -1 = authorized except for wireless USB, 49057bae0432SDmitry Torokhov 0 = not authorized, 1 = authorized, 2 = authorized 49067bae0432SDmitry Torokhov if device connected to internal port) 4907e52347bdSJani Nikula 4908e52347bdSJani Nikula usbcore.autosuspend= 4909e52347bdSJani Nikula [USB] The autosuspend time delay (in seconds) used 4910e52347bdSJani Nikula for newly-detected USB devices (default 2). This 4911e52347bdSJani Nikula is the time required before an idle device will be 4912e52347bdSJani Nikula autosuspended. Devices for which the delay is set 4913e52347bdSJani Nikula to a negative value won't be autosuspended at all. 4914e52347bdSJani Nikula 4915e52347bdSJani Nikula usbcore.usbfs_snoop= 4916e52347bdSJani Nikula [USB] Set to log all usbfs traffic (default 0 = off). 4917e52347bdSJani Nikula 4918e52347bdSJani Nikula usbcore.usbfs_snoop_max= 4919e52347bdSJani Nikula [USB] Maximum number of bytes to snoop in each URB 4920e52347bdSJani Nikula (default = 65536). 4921e52347bdSJani Nikula 4922e52347bdSJani Nikula usbcore.blinkenlights= 4923e52347bdSJani Nikula [USB] Set to cycle leds on hubs (default 0 = off). 4924e52347bdSJani Nikula 4925e52347bdSJani Nikula usbcore.old_scheme_first= 4926e52347bdSJani Nikula [USB] Start with the old device initialization 4927bd0e6c96SZeng Tao scheme, applies only to low and full-speed devices 4928bd0e6c96SZeng Tao (default 0 = off). 4929e52347bdSJani Nikula 4930e52347bdSJani Nikula usbcore.usbfs_memory_mb= 4931e52347bdSJani Nikula [USB] Memory limit (in MB) for buffers allocated by 4932e52347bdSJani Nikula usbfs (default = 16, 0 = max = 2047). 4933e52347bdSJani Nikula 4934e52347bdSJani Nikula usbcore.use_both_schemes= 4935e52347bdSJani Nikula [USB] Try the other device initialization scheme 4936e52347bdSJani Nikula if the first one fails (default 1 = enabled). 4937e52347bdSJani Nikula 4938e52347bdSJani Nikula usbcore.initial_descriptor_timeout= 4939e52347bdSJani Nikula [USB] Specifies timeout for the initial 64-byte 4940e52347bdSJani Nikula USB_REQ_GET_DESCRIPTOR request in milliseconds 4941e52347bdSJani Nikula (default 5000 = 5.0 seconds). 4942e52347bdSJani Nikula 4943e52347bdSJani Nikula usbcore.nousb [USB] Disable the USB subsystem 4944e52347bdSJani Nikula 4945027bd6caSKai-Heng Feng usbcore.quirks= 4946027bd6caSKai-Heng Feng [USB] A list of quirk entries to augment the built-in 4947027bd6caSKai-Heng Feng usb core quirk list. List entries are separated by 4948027bd6caSKai-Heng Feng commas. Each entry has the form 4949027bd6caSKai-Heng Feng VendorID:ProductID:Flags. The IDs are 4-digit hex 4950027bd6caSKai-Heng Feng numbers and Flags is a set of letters. Each letter 4951027bd6caSKai-Heng Feng will change the built-in quirk; setting it if it is 4952027bd6caSKai-Heng Feng clear and clearing it if it is set. The letters have 4953027bd6caSKai-Heng Feng the following meanings: 4954027bd6caSKai-Heng Feng a = USB_QUIRK_STRING_FETCH_255 (string 4955027bd6caSKai-Heng Feng descriptors must not be fetched using 4956027bd6caSKai-Heng Feng a 255-byte read); 4957027bd6caSKai-Heng Feng b = USB_QUIRK_RESET_RESUME (device can't resume 4958027bd6caSKai-Heng Feng correctly so reset it instead); 4959027bd6caSKai-Heng Feng c = USB_QUIRK_NO_SET_INTF (device can't handle 4960027bd6caSKai-Heng Feng Set-Interface requests); 4961027bd6caSKai-Heng Feng d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't 4962027bd6caSKai-Heng Feng handle its Configuration or Interface 4963027bd6caSKai-Heng Feng strings); 4964027bd6caSKai-Heng Feng e = USB_QUIRK_RESET (device can't be reset 4965027bd6caSKai-Heng Feng (e.g morph devices), don't use reset); 4966027bd6caSKai-Heng Feng f = USB_QUIRK_HONOR_BNUMINTERFACES (device has 4967027bd6caSKai-Heng Feng more interface descriptions than the 4968027bd6caSKai-Heng Feng bNumInterfaces count, and can't handle 4969027bd6caSKai-Heng Feng talking to these interfaces); 4970027bd6caSKai-Heng Feng g = USB_QUIRK_DELAY_INIT (device needs a pause 4971027bd6caSKai-Heng Feng during initialization, after we read 4972027bd6caSKai-Heng Feng the device descriptor); 4973027bd6caSKai-Heng Feng h = USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL (For 4974027bd6caSKai-Heng Feng high speed and super speed interrupt 4975027bd6caSKai-Heng Feng endpoints, the USB 2.0 and USB 3.0 spec 4976027bd6caSKai-Heng Feng require the interval in microframes (1 4977027bd6caSKai-Heng Feng microframe = 125 microseconds) to be 4978027bd6caSKai-Heng Feng calculated as interval = 2 ^ 4979027bd6caSKai-Heng Feng (bInterval-1). 4980027bd6caSKai-Heng Feng Devices with this quirk report their 4981027bd6caSKai-Heng Feng bInterval as the result of this 4982027bd6caSKai-Heng Feng calculation instead of the exponent 4983027bd6caSKai-Heng Feng variable used in the calculation); 4984027bd6caSKai-Heng Feng i = USB_QUIRK_DEVICE_QUALIFIER (device can't 4985027bd6caSKai-Heng Feng handle device_qualifier descriptor 4986027bd6caSKai-Heng Feng requests); 4987027bd6caSKai-Heng Feng j = USB_QUIRK_IGNORE_REMOTE_WAKEUP (device 4988027bd6caSKai-Heng Feng generates spurious wakeup, ignore 4989027bd6caSKai-Heng Feng remote wakeup capability); 4990027bd6caSKai-Heng Feng k = USB_QUIRK_NO_LPM (device can't handle Link 4991027bd6caSKai-Heng Feng Power Management); 4992027bd6caSKai-Heng Feng l = USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL 4993027bd6caSKai-Heng Feng (Device reports its bInterval as linear 4994027bd6caSKai-Heng Feng frames instead of the USB 2.0 4995027bd6caSKai-Heng Feng calculation); 4996027bd6caSKai-Heng Feng m = USB_QUIRK_DISCONNECT_SUSPEND (Device needs 4997027bd6caSKai-Heng Feng to be disconnected before suspend to 49984d8d5a39SKai-Heng Feng prevent spurious wakeup); 49994d8d5a39SKai-Heng Feng n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a 50004d8d5a39SKai-Heng Feng pause after every control message); 5001781f0766SKai-Heng Feng o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra 5002781f0766SKai-Heng Feng delay after resetting its port); 5003027bd6caSKai-Heng Feng Example: quirks=0781:5580:bk,0a5c:5834:gij 5004027bd6caSKai-Heng Feng 5005e52347bdSJani Nikula usbhid.mousepoll= 5006e52347bdSJani Nikula [USBHID] The interval which mice are to be polled at. 5007e52347bdSJani Nikula 5008933bfe4dSTobias Jakobi usbhid.jspoll= 5009933bfe4dSTobias Jakobi [USBHID] The interval which joysticks are to be polled at. 5010933bfe4dSTobias Jakobi 50112ddc8e2dSFilip Alac usbhid.kbpoll= 50122ddc8e2dSFilip Alac [USBHID] The interval which keyboards are to be polled at. 50132ddc8e2dSFilip Alac 5014e52347bdSJani Nikula usb-storage.delay_use= 5015e52347bdSJani Nikula [UMS] The delay in seconds before a new device is 5016e52347bdSJani Nikula scanned for Logical Units (default 1). 5017e52347bdSJani Nikula 5018e52347bdSJani Nikula usb-storage.quirks= 5019e52347bdSJani Nikula [UMS] A list of quirks entries to supplement or 5020e52347bdSJani Nikula override the built-in unusual_devs list. List 5021e52347bdSJani Nikula entries are separated by commas. Each entry has 5022e52347bdSJani Nikula the form VID:PID:Flags where VID and PID are Vendor 5023e52347bdSJani Nikula and Product ID values (4-digit hex numbers) and 5024e52347bdSJani Nikula Flags is a set of characters, each corresponding 5025e52347bdSJani Nikula to a common usb-storage quirk flag as follows: 5026e52347bdSJani Nikula a = SANE_SENSE (collect more than 18 bytes 5027e52347bdSJani Nikula of sense data); 5028e52347bdSJani Nikula b = BAD_SENSE (don't collect more than 18 5029e52347bdSJani Nikula bytes of sense data); 5030e52347bdSJani Nikula c = FIX_CAPACITY (decrease the reported 5031e52347bdSJani Nikula device capacity by one sector); 5032e52347bdSJani Nikula d = NO_READ_DISC_INFO (don't use 5033e52347bdSJani Nikula READ_DISC_INFO command); 5034e52347bdSJani Nikula e = NO_READ_CAPACITY_16 (don't use 5035e52347bdSJani Nikula READ_CAPACITY_16 command); 5036e52347bdSJani Nikula f = NO_REPORT_OPCODES (don't use report opcodes 5037e52347bdSJani Nikula command, uas only); 5038e52347bdSJani Nikula g = MAX_SECTORS_240 (don't transfer more than 5039e52347bdSJani Nikula 240 sectors at a time, uas only); 5040e52347bdSJani Nikula h = CAPACITY_HEURISTICS (decrease the 5041e52347bdSJani Nikula reported device capacity by one 5042e52347bdSJani Nikula sector if the number is odd); 5043e52347bdSJani Nikula i = IGNORE_DEVICE (don't bind to this 5044e52347bdSJani Nikula device); 5045e52347bdSJani Nikula j = NO_REPORT_LUNS (don't use report luns 5046e52347bdSJani Nikula command, uas only); 5047e52347bdSJani Nikula l = NOT_LOCKABLE (don't try to lock and 5048e52347bdSJani Nikula unlock ejectable media); 5049e52347bdSJani Nikula m = MAX_SECTORS_64 (don't transfer more 5050e52347bdSJani Nikula than 64 sectors = 32 KB at a time); 5051e52347bdSJani Nikula n = INITIAL_READ10 (force a retry of the 5052e52347bdSJani Nikula initial READ(10) command); 5053e52347bdSJani Nikula o = CAPACITY_OK (accept the capacity 5054e52347bdSJani Nikula reported by the device); 5055e52347bdSJani Nikula p = WRITE_CACHE (the device cache is ON 5056e52347bdSJani Nikula by default); 5057e52347bdSJani Nikula r = IGNORE_RESIDUE (the device reports 5058e52347bdSJani Nikula bogus residue values); 5059e52347bdSJani Nikula s = SINGLE_LUN (the device has only one 5060e52347bdSJani Nikula Logical Unit); 5061e52347bdSJani Nikula t = NO_ATA_1X (don't allow ATA(12) and ATA(16) 5062e52347bdSJani Nikula commands, uas only); 5063e52347bdSJani Nikula u = IGNORE_UAS (don't bind to the uas driver); 5064e52347bdSJani Nikula w = NO_WP_DETECT (don't test whether the 5065e52347bdSJani Nikula medium is write-protected). 5066e52347bdSJani Nikula y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE 5067e52347bdSJani Nikula even if the device claims no cache) 5068e52347bdSJani Nikula Example: quirks=0419:aaf5:rl,0421:0433:rc 5069e52347bdSJani Nikula 5070e52347bdSJani Nikula user_debug= [KNL,ARM] 5071e52347bdSJani Nikula Format: <int> 5072e52347bdSJani Nikula See arch/arm/Kconfig.debug help text. 5073e52347bdSJani Nikula 1 - undefined instruction events 5074e52347bdSJani Nikula 2 - system calls 5075e52347bdSJani Nikula 4 - invalid data aborts 5076e52347bdSJani Nikula 8 - SIGSEGV faults 5077e52347bdSJani Nikula 16 - SIGBUS faults 5078e52347bdSJani Nikula Example: user_debug=31 5079e52347bdSJani Nikula 5080e52347bdSJani Nikula userpte= 5081e52347bdSJani Nikula [X86] Flags controlling user PTE allocations. 5082e52347bdSJani Nikula 5083e52347bdSJani Nikula nohigh = do not allocate PTE pages in 5084e52347bdSJani Nikula HIGHMEM regardless of setting 5085e52347bdSJani Nikula of CONFIG_HIGHPTE. 5086e52347bdSJani Nikula 5087e52347bdSJani Nikula vdso= [X86,SH] 5088e52347bdSJani Nikula On X86_32, this is an alias for vdso32=. Otherwise: 5089e52347bdSJani Nikula 5090e52347bdSJani Nikula vdso=1: enable VDSO (the default) 5091e52347bdSJani Nikula vdso=0: disable VDSO mapping 5092e52347bdSJani Nikula 5093e52347bdSJani Nikula vdso32= [X86] Control the 32-bit vDSO 5094e52347bdSJani Nikula vdso32=1: enable 32-bit VDSO 5095e52347bdSJani Nikula vdso32=0 or vdso32=2: disable 32-bit VDSO 5096e52347bdSJani Nikula 5097e52347bdSJani Nikula See the help text for CONFIG_COMPAT_VDSO for more 5098e52347bdSJani Nikula details. If CONFIG_COMPAT_VDSO is set, the default is 5099e52347bdSJani Nikula vdso32=0; otherwise, the default is vdso32=1. 5100e52347bdSJani Nikula 5101e52347bdSJani Nikula For compatibility with older kernels, vdso32=2 is an 5102e52347bdSJani Nikula alias for vdso32=0. 5103e52347bdSJani Nikula 5104e52347bdSJani Nikula Try vdso32=0 if you encounter an error that says: 5105e52347bdSJani Nikula dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 5106e52347bdSJani Nikula 5107e52347bdSJani Nikula vector= [IA-64,SMP] 5108e52347bdSJani Nikula vector=percpu: enable percpu vector domain 5109e52347bdSJani Nikula 5110e52347bdSJani Nikula video= [FB] Frame buffer configuration 5111ab42b818SMauro Carvalho Chehab See Documentation/fb/modedb.rst. 5112e52347bdSJani Nikula 5113e52347bdSJani Nikula video.brightness_switch_enabled= [0,1] 5114e52347bdSJani Nikula If set to 1, on receiving an ACPI notify event 5115e52347bdSJani Nikula generated by hotkey, video driver will adjust brightness 5116e52347bdSJani Nikula level and then send out the event to user space through 5117e52347bdSJani Nikula the allocated input device; If set to 0, video driver 5118e52347bdSJani Nikula will only send out the event without touching backlight 5119e52347bdSJani Nikula brightness level. 5120e52347bdSJani Nikula default: 1 5121e52347bdSJani Nikula 5122e52347bdSJani Nikula virtio_mmio.device= 5123e52347bdSJani Nikula [VMMIO] Memory mapped virtio (platform) device. 5124e52347bdSJani Nikula 5125e52347bdSJani Nikula <size>@<baseaddr>:<irq>[:<id>] 5126e52347bdSJani Nikula where: 5127e52347bdSJani Nikula <size> := size (can use standard suffixes 5128e52347bdSJani Nikula like K, M and G) 5129e52347bdSJani Nikula <baseaddr> := physical base address 5130e52347bdSJani Nikula <irq> := interrupt number (as passed to 5131e52347bdSJani Nikula request_irq()) 5132e52347bdSJani Nikula <id> := (optional) platform device id 5133e52347bdSJani Nikula example: 5134e52347bdSJani Nikula virtio_mmio.device=1K@0x100b0000:48:7 5135e52347bdSJani Nikula 5136e52347bdSJani Nikula Can be used multiple times for multiple devices. 5137e52347bdSJani Nikula 5138e52347bdSJani Nikula vga= [BOOT,X86-32] Select a particular video mode 5139cb1aaebeSMauro Carvalho Chehab See Documentation/x86/boot.rst and 51404f4cfa6cSMauro Carvalho Chehab Documentation/admin-guide/svga.rst. 5141e52347bdSJani Nikula Use vga=ask for menu. 5142e52347bdSJani Nikula This is actually a boot loader parameter; the value is 5143e52347bdSJani Nikula passed to the kernel using a special protocol. 5144e52347bdSJani Nikula 5145f682a97aSAlexander Duyck vm_debug[=options] [KNL] Available with CONFIG_DEBUG_VM=y. 5146f682a97aSAlexander Duyck May slow down system boot speed, especially when 5147f682a97aSAlexander Duyck enabled on systems with a large amount of memory. 5148f682a97aSAlexander Duyck All options are enabled by default, and this 5149f682a97aSAlexander Duyck interface is meant to allow for selectively 5150f682a97aSAlexander Duyck enabling or disabling specific virtual memory 5151f682a97aSAlexander Duyck debugging features. 5152f682a97aSAlexander Duyck 5153f682a97aSAlexander Duyck Available options are: 5154f682a97aSAlexander Duyck P Enable page structure init time poisoning 5155f682a97aSAlexander Duyck - Disable all of the above options 5156f682a97aSAlexander Duyck 5157e52347bdSJani Nikula vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact 5158e52347bdSJani Nikula size of <nn>. This can be used to increase the 5159e52347bdSJani Nikula minimum size (128MB on x86). It can also be used to 5160e52347bdSJani Nikula decrease the size and leave more room for directly 5161e52347bdSJani Nikula mapped kernel RAM. 5162e52347bdSJani Nikula 51633f429842SHeiko Carstens vmcp_cma=nn[MG] [KNL,S390] 51643f429842SHeiko Carstens Sets the memory size reserved for contiguous memory 51653f429842SHeiko Carstens allocations for the vmcp device driver. 51663f429842SHeiko Carstens 5167e52347bdSJani Nikula vmhalt= [KNL,S390] Perform z/VM CP command after system halt. 5168e52347bdSJani Nikula Format: <command> 5169e52347bdSJani Nikula 5170e52347bdSJani Nikula vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. 5171e52347bdSJani Nikula Format: <command> 5172e52347bdSJani Nikula 5173e52347bdSJani Nikula vmpoff= [KNL,S390] Perform z/VM CP command after power off. 5174e52347bdSJani Nikula Format: <command> 5175e52347bdSJani Nikula 5176e52347bdSJani Nikula vsyscall= [X86-64] 5177e52347bdSJani Nikula Controls the behavior of vsyscalls (i.e. calls to 5178e52347bdSJani Nikula fixed addresses of 0xffffffffff600x00 from legacy 5179e52347bdSJani Nikula code). Most statically-linked binaries and older 5180e52347bdSJani Nikula versions of glibc use these calls. Because these 5181e52347bdSJani Nikula functions are at fixed addresses, they make nice 5182e52347bdSJani Nikula targets for exploits that can control RIP. 5183e52347bdSJani Nikula 5184e52347bdSJani Nikula emulate [default] Vsyscalls turn into traps and are 5185bd49e16eSAndy Lutomirski emulated reasonably safely. The vsyscall 5186bd49e16eSAndy Lutomirski page is readable. 5187e52347bdSJani Nikula 5188bd49e16eSAndy Lutomirski xonly Vsyscalls turn into traps and are 5189bd49e16eSAndy Lutomirski emulated reasonably safely. The vsyscall 5190bd49e16eSAndy Lutomirski page is not readable. 5191e52347bdSJani Nikula 5192e52347bdSJani Nikula none Vsyscalls don't work at all. This makes 5193e52347bdSJani Nikula them quite hard to use for exploits but 5194e52347bdSJani Nikula might break your system. 5195e52347bdSJani Nikula 5196e52347bdSJani Nikula vt.color= [VT] Default text color. 5197e52347bdSJani Nikula Format: 0xYX, X = foreground, Y = background. 5198e52347bdSJani Nikula Default: 0x07 = light gray on black. 5199e52347bdSJani Nikula 5200e52347bdSJani Nikula vt.cur_default= [VT] Default cursor shape. 5201e52347bdSJani Nikula Format: 0xCCBBAA, where AA, BB, and CC are the same as 5202e52347bdSJani Nikula the parameters of the <Esc>[?A;B;Cc escape sequence; 5203e52347bdSJani Nikula see VGA-softcursor.txt. Default: 2 = underline. 5204e52347bdSJani Nikula 5205e52347bdSJani Nikula vt.default_blu= [VT] 5206e52347bdSJani Nikula Format: <blue0>,<blue1>,<blue2>,...,<blue15> 5207e52347bdSJani Nikula Change the default blue palette of the console. 5208e52347bdSJani Nikula This is a 16-member array composed of values 5209e52347bdSJani Nikula ranging from 0-255. 5210e52347bdSJani Nikula 5211e52347bdSJani Nikula vt.default_grn= [VT] 5212e52347bdSJani Nikula Format: <green0>,<green1>,<green2>,...,<green15> 5213e52347bdSJani Nikula Change the default green palette of the console. 5214e52347bdSJani Nikula This is a 16-member array composed of values 5215e52347bdSJani Nikula ranging from 0-255. 5216e52347bdSJani Nikula 5217e52347bdSJani Nikula vt.default_red= [VT] 5218e52347bdSJani Nikula Format: <red0>,<red1>,<red2>,...,<red15> 5219e52347bdSJani Nikula Change the default red palette of the console. 5220e52347bdSJani Nikula This is a 16-member array composed of values 5221e52347bdSJani Nikula ranging from 0-255. 5222e52347bdSJani Nikula 5223e52347bdSJani Nikula vt.default_utf8= 5224e52347bdSJani Nikula [VT] 5225e52347bdSJani Nikula Format=<0|1> 5226e52347bdSJani Nikula Set system-wide default UTF-8 mode for all tty's. 5227e52347bdSJani Nikula Default is 1, i.e. UTF-8 mode is enabled for all 5228e52347bdSJani Nikula newly opened terminals. 5229e52347bdSJani Nikula 5230e52347bdSJani Nikula vt.global_cursor_default= 5231e52347bdSJani Nikula [VT] 5232e52347bdSJani Nikula Format=<-1|0|1> 5233e52347bdSJani Nikula Set system-wide default for whether a cursor 5234e52347bdSJani Nikula is shown on new VTs. Default is -1, 5235e52347bdSJani Nikula i.e. cursors will be created by default unless 5236e52347bdSJani Nikula overridden by individual drivers. 0 will hide 5237e52347bdSJani Nikula cursors, 1 will display them. 5238e52347bdSJani Nikula 5239e52347bdSJani Nikula vt.italic= [VT] Default color for italic text; 0-15. 5240e52347bdSJani Nikula Default: 2 = green. 5241e52347bdSJani Nikula 5242e52347bdSJani Nikula vt.underline= [VT] Default color for underlined text; 0-15. 5243e52347bdSJani Nikula Default: 3 = cyan. 5244e52347bdSJani Nikula 5245e52347bdSJani Nikula watchdog timers [HW,WDT] For information on watchdog timers, 5246cc2a2d19SMauro Carvalho Chehab see Documentation/watchdog/watchdog-parameters.rst 5247e52347bdSJani Nikula or other driver-specific files in the 5248e52347bdSJani Nikula Documentation/watchdog/ directory. 5249e52347bdSJani Nikula 525011295055SLaurence Oberman watchdog_thresh= 525111295055SLaurence Oberman [KNL] 525211295055SLaurence Oberman Set the hard lockup detector stall duration 525311295055SLaurence Oberman threshold in seconds. The soft lockup detector 525411295055SLaurence Oberman threshold is set to twice the value. A value of 0 525511295055SLaurence Oberman disables both lockup detectors. Default is 10 525611295055SLaurence Oberman seconds. 525711295055SLaurence Oberman 5258e52347bdSJani Nikula workqueue.watchdog_thresh= 5259e52347bdSJani Nikula If CONFIG_WQ_WATCHDOG is configured, workqueue can 5260e52347bdSJani Nikula warn stall conditions and dump internal state to 5261e52347bdSJani Nikula help debugging. 0 disables workqueue stall 5262e52347bdSJani Nikula detection; otherwise, it's the stall threshold 5263e52347bdSJani Nikula duration in seconds. The default value is 30 and 5264e52347bdSJani Nikula it can be updated at runtime by writing to the 5265e52347bdSJani Nikula corresponding sysfs file. 5266e52347bdSJani Nikula 5267e52347bdSJani Nikula workqueue.disable_numa 5268e52347bdSJani Nikula By default, all work items queued to unbound 5269e52347bdSJani Nikula workqueues are affine to the NUMA nodes they're 5270e52347bdSJani Nikula issued on, which results in better behavior in 5271e52347bdSJani Nikula general. If NUMA affinity needs to be disabled for 5272e52347bdSJani Nikula whatever reason, this option can be used. Note 5273e52347bdSJani Nikula that this also can be controlled per-workqueue for 5274e52347bdSJani Nikula workqueues visible under /sys/bus/workqueue/. 5275e52347bdSJani Nikula 5276e52347bdSJani Nikula workqueue.power_efficient 5277e52347bdSJani Nikula Per-cpu workqueues are generally preferred because 5278e52347bdSJani Nikula they show better performance thanks to cache 5279e52347bdSJani Nikula locality; unfortunately, per-cpu workqueues tend to 5280e52347bdSJani Nikula be more power hungry than unbound workqueues. 5281e52347bdSJani Nikula 5282e52347bdSJani Nikula Enabling this makes the per-cpu workqueues which 5283e52347bdSJani Nikula were observed to contribute significantly to power 5284e52347bdSJani Nikula consumption unbound, leading to measurably lower 5285e52347bdSJani Nikula power usage at the cost of small performance 5286e52347bdSJani Nikula overhead. 5287e52347bdSJani Nikula 5288e52347bdSJani Nikula The default value of this parameter is determined by 5289e52347bdSJani Nikula the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT. 5290e52347bdSJani Nikula 5291e52347bdSJani Nikula workqueue.debug_force_rr_cpu 5292e52347bdSJani Nikula Workqueue used to implicitly guarantee that work 5293e52347bdSJani Nikula items queued without explicit CPU specified are put 5294e52347bdSJani Nikula on the local CPU. This guarantee is no longer true 5295e52347bdSJani Nikula and while local CPU is still preferred work items 5296e52347bdSJani Nikula may be put on foreign CPUs. This debug option 5297e52347bdSJani Nikula forces round-robin CPU selection to flush out 5298e52347bdSJani Nikula usages which depend on the now broken guarantee. 5299e52347bdSJani Nikula When enabled, memory and cache locality will be 5300e52347bdSJani Nikula impacted. 5301e52347bdSJani Nikula 5302e52347bdSJani Nikula x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of 5303e52347bdSJani Nikula default x2apic cluster mode on platforms 5304e52347bdSJani Nikula supporting x2apic. 5305e52347bdSJani Nikula 5306e52347bdSJani Nikula x86_intel_mid_timer= [X86-32,APBT] 5307e52347bdSJani Nikula Choose timer option for x86 Intel MID platform. 5308e52347bdSJani Nikula Two valid options are apbt timer only and lapic timer 5309e52347bdSJani Nikula plus one apbt timer for broadcast timer. 5310e52347bdSJani Nikula x86_intel_mid_timer=apbt_only | lapic_and_apbt 5311e52347bdSJani Nikula 5312e52347bdSJani Nikula xen_512gb_limit [KNL,X86-64,XEN] 5313e52347bdSJani Nikula Restricts the kernel running paravirtualized under Xen 5314e52347bdSJani Nikula to use only up to 512 GB of RAM. The reason to do so is 5315e52347bdSJani Nikula crash analysis tools and Xen tools for doing domain 5316e52347bdSJani Nikula save/restore/migration must be enabled to handle larger 5317e52347bdSJani Nikula domains. 5318e52347bdSJani Nikula 5319e52347bdSJani Nikula xen_emul_unplug= [HW,X86,XEN] 5320e52347bdSJani Nikula Unplug Xen emulated devices 5321e52347bdSJani Nikula Format: [unplug0,][unplug1] 5322e52347bdSJani Nikula ide-disks -- unplug primary master IDE devices 5323e52347bdSJani Nikula aux-ide-disks -- unplug non-primary-master IDE devices 5324e52347bdSJani Nikula nics -- unplug network devices 5325e52347bdSJani Nikula all -- unplug all emulated devices (NICs and IDE disks) 5326e52347bdSJani Nikula unnecessary -- unplugging emulated devices is 5327e52347bdSJani Nikula unnecessary even if the host did not respond to 5328e52347bdSJani Nikula the unplug protocol 5329e52347bdSJani Nikula never -- do not unplug even if version check succeeds 5330e52347bdSJani Nikula 5331c6875f3aSBoris Ostrovsky xen_legacy_crash [X86,XEN] 5332c6875f3aSBoris Ostrovsky Crash from Xen panic notifier, without executing late 5333c6875f3aSBoris Ostrovsky panic() code such as dumping handler. 5334c6875f3aSBoris Ostrovsky 5335e52347bdSJani Nikula xen_nopvspin [X86,XEN] 5336e52347bdSJani Nikula Disables the ticketlock slowpath using Xen PV 5337e52347bdSJani Nikula optimizations. 5338e52347bdSJani Nikula 5339e52347bdSJani Nikula xen_nopv [X86] 5340e52347bdSJani Nikula Disables the PV optimizations forcing the HVM guest to 5341e52347bdSJani Nikula run as generic HVM guest with no PV drivers. 5342b39b0497SZhenzhong Duan This option is obsoleted by the "nopv" option, which 5343b39b0497SZhenzhong Duan has equivalent effect for XEN platform. 5344e52347bdSJani Nikula 5345197ecb38SMarek Marczykowski-Górecki xen_scrub_pages= [XEN] 5346197ecb38SMarek Marczykowski-Górecki Boolean option to control scrubbing pages before giving them back 5347197ecb38SMarek Marczykowski-Górecki to Xen, for use by other domains. Can be also changed at runtime 5348197ecb38SMarek Marczykowski-Górecki with /sys/devices/system/xen_memory/xen_memory0/scrub_pages. 5349197ecb38SMarek Marczykowski-Górecki Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT. 5350197ecb38SMarek Marczykowski-Górecki 53512ec16bc0SRyan Thibodeaux xen_timer_slop= [X86-64,XEN] 53522ec16bc0SRyan Thibodeaux Set the timer slop (in nanoseconds) for the virtual Xen 53532ec16bc0SRyan Thibodeaux timers (default is 100000). This adjusts the minimum 53542ec16bc0SRyan Thibodeaux delta of virtualized Xen timers, where lower values 53552ec16bc0SRyan Thibodeaux improve timer resolution at the expense of processing 53562ec16bc0SRyan Thibodeaux more timer interrupts. 53572ec16bc0SRyan Thibodeaux 535830978346SZhenzhong Duan nopv= [X86,XEN,KVM,HYPER_V,VMWARE] 535930978346SZhenzhong Duan Disables the PV optimizations forcing the guest to run 536030978346SZhenzhong Duan as generic guest with no PV drivers. Currently support 536130978346SZhenzhong Duan XEN HVM, KVM, HYPER_V and VMWARE guest. 536230978346SZhenzhong Duan 5363e52347bdSJani Nikula xirc2ps_cs= [NET,PCMCIA] 5364e52347bdSJani Nikula Format: 5365e52347bdSJani Nikula <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] 5366c0addc9aSLaurentiu Tudor 5367ba45cff6SMichael Neuling xive= [PPC] 5368ba45cff6SMichael Neuling By default on POWER9 and above, the kernel will 5369ba45cff6SMichael Neuling natively use the XIVE interrupt controller. This option 5370ba45cff6SMichael Neuling allows the fallback firmware mode to be used: 5371ba45cff6SMichael Neuling 5372ba45cff6SMichael Neuling off Fallback to firmware control of XIVE interrupt 5373ba45cff6SMichael Neuling controller on both pseries and powernv 5374ba45cff6SMichael Neuling platforms. Only useful on POWER9 and above. 5375ba45cff6SMichael Neuling 5376c0addc9aSLaurentiu Tudor xhci-hcd.quirks [USB,KNL] 5377c0addc9aSLaurentiu Tudor A hex value specifying bitmask with supplemental xhci 5378c0addc9aSLaurentiu Tudor host controller quirks. Meaning of each bit can be 5379c0addc9aSLaurentiu Tudor consulted in header drivers/usb/host/xhci.h. 53806278f55bSGustavo Romero 53816278f55bSGustavo Romero xmon [PPC] 53826278f55bSGustavo Romero Format: { early | on | rw | ro | off } 53836278f55bSGustavo Romero Controls if xmon debugger is enabled. Default is off. 53846278f55bSGustavo Romero Passing only "xmon" is equivalent to "xmon=early". 53856278f55bSGustavo Romero early Call xmon as early as possible on boot; xmon 53866278f55bSGustavo Romero debugger is called from setup_arch(). 53876278f55bSGustavo Romero on xmon debugger hooks will be installed so xmon 53886278f55bSGustavo Romero is only called on a kernel crash. Default mode, 53896278f55bSGustavo Romero i.e. either "ro" or "rw" mode, is controlled 53906278f55bSGustavo Romero with CONFIG_XMON_DEFAULT_RO_MODE. 53916278f55bSGustavo Romero rw xmon debugger hooks will be installed so xmon 53926278f55bSGustavo Romero is called only on a kernel crash, mode is write, 53936278f55bSGustavo Romero meaning SPR registers, memory and, other data 53946278f55bSGustavo Romero can be written using xmon commands. 53956278f55bSGustavo Romero ro same as "rw" option above but SPR registers, 53966278f55bSGustavo Romero memory, and other data can't be written using 53976278f55bSGustavo Romero xmon commands. 53986278f55bSGustavo Romero off xmon is disabled. 5399