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] 255fd769c2SRandy Dunlap { vendor | video | native | none } 265fd769c2SRandy Dunlap If set to vendor, prefer vendor-specific driver 27e52347bdSJani Nikula (e.g. thinkpad_acpi, sony_acpi, etc.) instead 28e52347bdSJani Nikula of the ACPI video.ko driver. 295fd769c2SRandy Dunlap If set to video, use the ACPI video.ko driver. 305fd769c2SRandy Dunlap If set to native, use the device's native backlight mode. 315fd769c2SRandy Dunlap If set to none, disable the ACPI backlight interface. 32e52347bdSJani Nikula 33e52347bdSJani Nikula acpi_force_32bit_fadt_addr 34e52347bdSJani Nikula force FADT to use 32 bit addresses rather than the 35e52347bdSJani Nikula 64 bit X_* addresses. Some firmware have broken 64 36e52347bdSJani Nikula bit addresses for force ACPI ignore these and use 37e52347bdSJani Nikula the older legacy 32 bit addresses. 38e52347bdSJani Nikula 39e52347bdSJani Nikula acpica_no_return_repair [HW, ACPI] 40e52347bdSJani Nikula Disable AML predefined validation mechanism 41e52347bdSJani Nikula This mechanism can repair the evaluation result to make 42e52347bdSJani Nikula the return objects more ACPI specification compliant. 43e52347bdSJani Nikula This option is useful for developers to identify the 44e52347bdSJani Nikula root cause of an AML interpreter issue when the issue 45e52347bdSJani Nikula has something to do with the repair mechanism. 46e52347bdSJani Nikula 47e52347bdSJani Nikula acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] 48e52347bdSJani Nikula acpi.debug_level= [HW,ACPI,ACPI_DEBUG] 49e52347bdSJani Nikula Format: <int> 50e52347bdSJani Nikula CONFIG_ACPI_DEBUG must be enabled to produce any ACPI 51e52347bdSJani Nikula debug output. Bits in debug_layer correspond to a 52e52347bdSJani Nikula _COMPONENT in an ACPI source file, e.g., 53e52347bdSJani Nikula #define _COMPONENT ACPI_PCI_COMPONENT 54e52347bdSJani Nikula Bits in debug_level correspond to a level in 55e52347bdSJani Nikula ACPI_DEBUG_PRINT statements, e.g., 56e52347bdSJani Nikula ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... 57e52347bdSJani Nikula The debug_level mask defaults to "info". See 58cb1aaebeSMauro Carvalho Chehab Documentation/firmware-guide/acpi/debug.rst for more information about 59e52347bdSJani Nikula debug layers and levels. 60e52347bdSJani Nikula 61e52347bdSJani Nikula Enable processor driver info messages: 62e52347bdSJani Nikula acpi.debug_layer=0x20000000 63e52347bdSJani Nikula Enable PCI/PCI interrupt routing info messages: 64e52347bdSJani Nikula acpi.debug_layer=0x400000 65e52347bdSJani Nikula Enable AML "Debug" output, i.e., stores to the Debug 66e52347bdSJani Nikula object while interpreting AML: 67e52347bdSJani Nikula acpi.debug_layer=0xffffffff acpi.debug_level=0x2 68e52347bdSJani Nikula Enable all messages related to ACPI hardware: 69e52347bdSJani Nikula acpi.debug_layer=0x2 acpi.debug_level=0xffffffff 70e52347bdSJani Nikula 71e52347bdSJani Nikula Some values produce so much output that the system is 72e52347bdSJani Nikula unusable. The "log_buf_len" parameter may be useful 73e52347bdSJani Nikula if you need to capture more output. 74e52347bdSJani Nikula 75e52347bdSJani Nikula acpi_enforce_resources= [ACPI] 76e52347bdSJani Nikula { strict | lax | no } 77e52347bdSJani Nikula Check for resource conflicts between native drivers 78e52347bdSJani Nikula and ACPI OperationRegions (SystemIO and SystemMemory 79e52347bdSJani Nikula only). IO ports and memory declared in ACPI might be 80e52347bdSJani Nikula used by the ACPI subsystem in arbitrary AML code and 81e52347bdSJani Nikula can interfere with legacy drivers. 82e52347bdSJani Nikula strict (default): access to resources claimed by ACPI 83e52347bdSJani Nikula is denied; legacy drivers trying to access reserved 84e52347bdSJani Nikula resources will fail to bind to device using them. 85e52347bdSJani Nikula lax: access to resources claimed by ACPI is allowed; 86e52347bdSJani Nikula legacy drivers trying to access reserved resources 87e52347bdSJani Nikula will bind successfully but a warning message is logged. 88e52347bdSJani Nikula no: ACPI OperationRegions are not marked as reserved, 89e52347bdSJani Nikula no further checks are performed. 90e52347bdSJani Nikula 91e52347bdSJani Nikula acpi_force_table_verification [HW,ACPI] 92e52347bdSJani Nikula Enable table checksum verification during early stage. 93e52347bdSJani Nikula By default, this is disabled due to x86 early mapping 94e52347bdSJani Nikula size limitation. 95e52347bdSJani Nikula 96e52347bdSJani Nikula acpi_irq_balance [HW,ACPI] 97e52347bdSJani Nikula ACPI will balance active IRQs 98e52347bdSJani Nikula default in APIC mode 99e52347bdSJani Nikula 100e52347bdSJani Nikula acpi_irq_nobalance [HW,ACPI] 101e52347bdSJani Nikula ACPI will not move active IRQs (default) 102e52347bdSJani Nikula default in PIC mode 103e52347bdSJani Nikula 104e52347bdSJani Nikula acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA 105e52347bdSJani Nikula Format: <irq>,<irq>... 106e52347bdSJani Nikula 107e52347bdSJani Nikula acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for 108e52347bdSJani Nikula use by PCI 109e52347bdSJani Nikula Format: <irq>,<irq>... 110e52347bdSJani Nikula 1119c4aa1eeSLv Zheng acpi_mask_gpe= [HW,ACPI] 1129c4aa1eeSLv Zheng Due to the existence of _Lxx/_Exx, some GPEs triggered 1139c4aa1eeSLv Zheng by unsupported hardware/firmware features can result in 1149c4aa1eeSLv Zheng GPE floodings that cannot be automatically disabled by 1159c4aa1eeSLv Zheng the GPE dispatcher. 1169c4aa1eeSLv Zheng This facility can be used to prevent such uncontrolled 1179c4aa1eeSLv Zheng GPE floodings. 118a7583e72SYunfeng Ye Format: <byte> 1199c4aa1eeSLv Zheng 120e52347bdSJani Nikula acpi_no_auto_serialize [HW,ACPI] 121e52347bdSJani Nikula Disable auto-serialization of AML methods 122e52347bdSJani Nikula AML control methods that contain the opcodes to create 123e52347bdSJani Nikula named objects will be marked as "Serialized" by the 124e52347bdSJani Nikula auto-serialization feature. 125e52347bdSJani Nikula This feature is enabled by default. 126e52347bdSJani Nikula This option allows to turn off the feature. 127e52347bdSJani Nikula 128e52347bdSJani Nikula acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump 129e52347bdSJani Nikula kernels. 130e52347bdSJani Nikula 131e52347bdSJani Nikula acpi_no_static_ssdt [HW,ACPI] 132e52347bdSJani Nikula Disable installation of static SSDTs at early boot time 133e52347bdSJani Nikula By default, SSDTs contained in the RSDT/XSDT will be 134e52347bdSJani Nikula installed automatically and they will appear under 135e52347bdSJani Nikula /sys/firmware/acpi/tables. 136e52347bdSJani Nikula This option turns off this feature. 137e52347bdSJani Nikula Note that specifying this option does not affect 138e52347bdSJani Nikula dynamic table installation which will install SSDT 139e52347bdSJani Nikula tables to /sys/firmware/acpi/tables/dynamic. 140e52347bdSJani Nikula 1413f9e12e0SJean Delvare acpi_no_watchdog [HW,ACPI,WDT] 1423f9e12e0SJean Delvare Ignore the ACPI-based watchdog interface (WDAT) and let 1433f9e12e0SJean Delvare a native driver control the watchdog device instead. 1443f9e12e0SJean Delvare 145e52347bdSJani Nikula acpi_rsdp= [ACPI,EFI,KEXEC] 146e52347bdSJani Nikula Pass the RSDP address to the kernel, mostly used 147e52347bdSJani Nikula on machines running EFI runtime service to boot the 148e52347bdSJani Nikula second kernel for kdump. 149e52347bdSJani Nikula 150e52347bdSJani Nikula acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS 151e52347bdSJani Nikula Format: To spoof as Windows 98: ="Microsoft Windows" 152e52347bdSJani Nikula 153e52347bdSJani Nikula acpi_rev_override [ACPI] Override the _REV object to return 5 (instead 154e52347bdSJani Nikula of 2 which is mandated by ACPI 6) as the supported ACPI 155e52347bdSJani Nikula specification revision (when using this switch, it may 156e52347bdSJani Nikula be necessary to carry out a cold reboot _twice_ in a 157e52347bdSJani Nikula row to make it take effect on the platform firmware). 158e52347bdSJani Nikula 159e52347bdSJani Nikula acpi_osi= [HW,ACPI] Modify list of supported OS interface strings 160e52347bdSJani Nikula acpi_osi="string1" # add string1 161e52347bdSJani Nikula acpi_osi="!string2" # remove string2 162e52347bdSJani Nikula acpi_osi=!* # remove all strings 163e52347bdSJani Nikula acpi_osi=! # disable all built-in OS vendor 164e52347bdSJani Nikula strings 165e52347bdSJani Nikula acpi_osi=!! # enable all built-in OS vendor 166e52347bdSJani Nikula strings 167e52347bdSJani Nikula acpi_osi= # disable all strings 168e52347bdSJani Nikula 169e52347bdSJani Nikula 'acpi_osi=!' can be used in combination with single or 170e52347bdSJani Nikula multiple 'acpi_osi="string1"' to support specific OS 171e52347bdSJani Nikula vendor string(s). Note that such command can only 172e52347bdSJani Nikula affect the default state of the OS vendor strings, thus 173e52347bdSJani Nikula it cannot affect the default state of the feature group 174e52347bdSJani Nikula strings and the current state of the OS vendor strings, 175e52347bdSJani Nikula specifying it multiple times through kernel command line 176e52347bdSJani Nikula is meaningless. This command is useful when one do not 177e52347bdSJani Nikula care about the state of the feature group strings which 178e52347bdSJani Nikula should be controlled by the OSPM. 179e52347bdSJani Nikula Examples: 180e52347bdSJani Nikula 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent 181e52347bdSJani Nikula to 'acpi_osi="Windows 2000" acpi_osi=!', they all 182e52347bdSJani Nikula can make '_OSI("Windows 2000")' TRUE. 183e52347bdSJani Nikula 184e52347bdSJani Nikula 'acpi_osi=' cannot be used in combination with other 185e52347bdSJani Nikula 'acpi_osi=' command lines, the _OSI method will not 186e52347bdSJani Nikula exist in the ACPI namespace. NOTE that such command can 187e52347bdSJani Nikula only affect the _OSI support state, thus specifying it 188e52347bdSJani Nikula multiple times through kernel command line is also 189e52347bdSJani Nikula meaningless. 190e52347bdSJani Nikula Examples: 191e52347bdSJani Nikula 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' 192e52347bdSJani Nikula FALSE. 193e52347bdSJani Nikula 194e52347bdSJani Nikula 'acpi_osi=!*' can be used in combination with single or 195e52347bdSJani Nikula multiple 'acpi_osi="string1"' to support specific 196e52347bdSJani Nikula string(s). Note that such command can affect the 197e52347bdSJani Nikula current state of both the OS vendor strings and the 198e52347bdSJani Nikula feature group strings, thus specifying it multiple times 199e52347bdSJani Nikula through kernel command line is meaningful. But it may 200e52347bdSJani Nikula still not able to affect the final state of a string if 201e52347bdSJani Nikula there are quirks related to this string. This command 202e52347bdSJani Nikula is useful when one want to control the state of the 203e52347bdSJani Nikula feature group strings to debug BIOS issues related to 204e52347bdSJani Nikula the OSPM features. 205e52347bdSJani Nikula Examples: 206e52347bdSJani Nikula 1. 'acpi_osi="Module Device" acpi_osi=!*' can make 207e52347bdSJani Nikula '_OSI("Module Device")' FALSE. 208e52347bdSJani Nikula 2. 'acpi_osi=!* acpi_osi="Module Device"' can make 209e52347bdSJani Nikula '_OSI("Module Device")' TRUE. 210e52347bdSJani Nikula 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is 211e52347bdSJani Nikula equivalent to 212e52347bdSJani Nikula 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' 213e52347bdSJani Nikula and 214e52347bdSJani Nikula 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', 215e52347bdSJani Nikula they all will make '_OSI("Windows 2000")' TRUE. 216e52347bdSJani Nikula 217e52347bdSJani Nikula acpi_pm_good [X86] 218e52347bdSJani Nikula Override the pmtimer bug detection: force the kernel 219e52347bdSJani Nikula to assume that this machine's pmtimer latches its value 220e52347bdSJani Nikula and always returns good values. 221e52347bdSJani Nikula 222e52347bdSJani Nikula acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode 223e52347bdSJani Nikula Format: { level | edge | high | low } 224e52347bdSJani Nikula 225e52347bdSJani Nikula acpi_skip_timer_override [HW,ACPI] 226e52347bdSJani Nikula Recognize and ignore IRQ0/pin2 Interrupt Override. 227e52347bdSJani Nikula For broken nForce2 BIOS resulting in XT-PIC timer. 228e52347bdSJani Nikula 229e52347bdSJani Nikula acpi_sleep= [HW,ACPI] Sleep options 230e52347bdSJani Nikula Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, 23157044031SRafael J. Wysocki old_ordering, nonvs, sci_force_enable, nobl } 232151f4e2bSMauro Carvalho Chehab See Documentation/power/video.rst for information on 233e52347bdSJani Nikula s3_bios and s3_mode. 234e52347bdSJani Nikula s3_beep is for debugging; it makes the PC's speaker beep 235e52347bdSJani Nikula as soon as the kernel's real-mode entry point is called. 236e52347bdSJani Nikula s4_nohwsig prevents ACPI hardware signature from being 237e52347bdSJani Nikula used during resume from hibernation. 238e52347bdSJani Nikula old_ordering causes the ACPI 1.0 ordering of the _PTS 239e52347bdSJani Nikula control method, with respect to putting devices into 240e52347bdSJani Nikula low power states, to be enforced (the ACPI 2.0 ordering 241e52347bdSJani Nikula of _PTS is used by default). 242e52347bdSJani Nikula nonvs prevents the kernel from saving/restoring the 243e52347bdSJani Nikula ACPI NVS memory during suspend/hibernation and resume. 244e52347bdSJani Nikula sci_force_enable causes the kernel to set SCI_EN directly 245e52347bdSJani Nikula on resume from S1/S3 (which is against the ACPI spec, 246e52347bdSJani Nikula but some broken systems don't work without it). 24757044031SRafael J. Wysocki nobl causes the internal blacklist of systems known to 24857044031SRafael J. Wysocki behave incorrectly in some ways with respect to system 24957044031SRafael J. Wysocki suspend and resume to be ignored (use wisely). 250e52347bdSJani Nikula 251e52347bdSJani Nikula acpi_use_timer_override [HW,ACPI] 252e52347bdSJani Nikula Use timer override. For some broken Nvidia NF5 boards 253e52347bdSJani Nikula that require a timer override, but don't have HPET 254e52347bdSJani Nikula 255e52347bdSJani Nikula add_efi_memmap [EFI; X86] Include EFI memory map in 256e52347bdSJani Nikula kernel's map of available physical RAM. 257e52347bdSJani Nikula 258e52347bdSJani Nikula agp= [AGP] 259e52347bdSJani Nikula { off | try_unsupported } 260e52347bdSJani Nikula off: disable AGP support 261e52347bdSJani Nikula try_unsupported: try to drive unsupported chipsets 262e52347bdSJani Nikula (may crash computer or cause data corruption) 263e52347bdSJani Nikula 264e52347bdSJani Nikula ALSA [HW,ALSA] 2651ca2c806SMauro Carvalho Chehab See Documentation/sound/alsa-configuration.rst 266e52347bdSJani Nikula 267e52347bdSJani Nikula alignment= [KNL,ARM] 268e52347bdSJani Nikula Allow the default userspace alignment fault handler 269e52347bdSJani Nikula behaviour to be specified. Bit 0 enables warnings, 270e52347bdSJani Nikula bit 1 enables fixups, and bit 2 sends a segfault. 271e52347bdSJani Nikula 272e52347bdSJani Nikula align_va_addr= [X86-64] 273e52347bdSJani Nikula Align virtual addresses by clearing slice [14:12] when 274e52347bdSJani Nikula allocating a VMA at process creation time. This option 275e52347bdSJani Nikula gives you up to 3% performance improvement on AMD F15h 276e52347bdSJani Nikula machines (where it is enabled by default) for a 277e52347bdSJani Nikula CPU-intensive style benchmark, and it can vary highly in 278e52347bdSJani Nikula a microbenchmark depending on workload and compiler. 279e52347bdSJani Nikula 280e52347bdSJani Nikula 32: only for 32-bit processes 281e52347bdSJani Nikula 64: only for 64-bit processes 282e52347bdSJani Nikula on: enable for both 32- and 64-bit processes 283e52347bdSJani Nikula off: disable for both 32- and 64-bit processes 284e52347bdSJani Nikula 285e52347bdSJani Nikula alloc_snapshot [FTRACE] 286e52347bdSJani Nikula Allocate the ftrace snapshot buffer on boot up when the 287e52347bdSJani Nikula main buffer is allocated. This is handy if debugging 288e52347bdSJani Nikula and you need to use tracing_snapshot() on boot up, and 289e52347bdSJani Nikula do not want to use tracing_snapshot_alloc() as it needs 290e52347bdSJani Nikula to be done where GFP_KERNEL allocations are allowed. 291e52347bdSJani Nikula 292e52347bdSJani Nikula amd_iommu= [HW,X86-64] 293e52347bdSJani Nikula Pass parameters to the AMD IOMMU driver in the system. 294e52347bdSJani Nikula Possible values are: 295e52347bdSJani Nikula fullflush - enable flushing of IO/TLB entries when 296e52347bdSJani Nikula they are unmapped. Otherwise they are 297e52347bdSJani Nikula flushed before they will be reused, which 298e52347bdSJani Nikula is a lot of faster 299e52347bdSJani Nikula off - do not initialize any AMD IOMMU found in 300e52347bdSJani Nikula the system 301e52347bdSJani Nikula force_isolation - Force device isolation for all 302e52347bdSJani Nikula devices. The IOMMU driver is not 303e52347bdSJani Nikula allowed anymore to lift isolation 304e52347bdSJani Nikula requirements as needed. This option 305e52347bdSJani Nikula does not override iommu=pt 306e52347bdSJani Nikula 307e52347bdSJani Nikula amd_iommu_dump= [HW,X86-64] 308e52347bdSJani Nikula Enable AMD IOMMU driver option to dump the ACPI table 309e52347bdSJani Nikula for AMD IOMMU. With this option enabled, AMD IOMMU 310e52347bdSJani Nikula driver will print ACPI tables for AMD IOMMU during 311e52347bdSJani Nikula IOMMU initialization. 312e52347bdSJani Nikula 313e52347bdSJani Nikula amd_iommu_intr= [HW,X86-64] 314e52347bdSJani Nikula Specifies one of the following AMD IOMMU interrupt 315e52347bdSJani Nikula remapping modes: 316e52347bdSJani Nikula legacy - Use legacy interrupt remapping mode. 317e52347bdSJani Nikula vapic - Use virtual APIC mode, which allows IOMMU 318e52347bdSJani Nikula to inject interrupts directly into guest. 319e52347bdSJani Nikula This mode requires kvm-amd.avic=1. 320e52347bdSJani Nikula (Default when IOMMU HW support is present.) 321e52347bdSJani Nikula 322e52347bdSJani Nikula amijoy.map= [HW,JOY] Amiga joystick support 323e52347bdSJani Nikula Map of devices attached to JOY0DAT and JOY1DAT 324e52347bdSJani Nikula Format: <a>,<b> 3251752118dSTom Saeger See also Documentation/input/joydev/joystick.rst 326e52347bdSJani Nikula 327e52347bdSJani Nikula analog.map= [HW,JOY] Analog joystick and gamepad support 328e52347bdSJani Nikula Specifies type or capabilities of an analog joystick 329e52347bdSJani Nikula connected to one of 16 gameports 330e52347bdSJani Nikula Format: <type1>,<type2>,..<type16> 331e52347bdSJani Nikula 332e52347bdSJani Nikula apc= [HW,SPARC] 333e52347bdSJani Nikula Power management functions (SPARCstation-4/5 + deriv.) 334e52347bdSJani Nikula Format: noidle 335e52347bdSJani Nikula Disable APC CPU standby support. SPARCstation-Fox does 336e52347bdSJani Nikula not play well with APC CPU idle - disable it if you have 337e52347bdSJani Nikula APC and your system crashes randomly. 338e52347bdSJani Nikula 33964e05d11SDou Liyang apic= [APIC,X86] Advanced Programmable Interrupt Controller 340806654a9SWill Deacon Change the output verbosity while booting 341e52347bdSJani Nikula Format: { quiet (default) | verbose | debug } 342e52347bdSJani Nikula Change the amount of debugging information output 343e52347bdSJani Nikula when initialising the APIC and IO-APIC components. 34464e05d11SDou Liyang For X86-32, this can also be used to specify an APIC 34564e05d11SDou Liyang driver name. 34664e05d11SDou Liyang Format: apic=driver_name 34764e05d11SDou Liyang Examples: apic=bigsmp 348e52347bdSJani Nikula 349e52347bdSJani Nikula apic_extnmi= [APIC,X86] External NMI delivery setting 350e52347bdSJani Nikula Format: { bsp (default) | all | none } 351e52347bdSJani Nikula bsp: External NMI is delivered only to CPU 0 352e52347bdSJani Nikula all: External NMIs are broadcast to all CPUs as a 353e52347bdSJani Nikula backup of CPU 0 354e52347bdSJani Nikula none: External NMI is masked for all CPUs. This is 355e52347bdSJani Nikula useful so that a dump capture kernel won't be 356e52347bdSJani Nikula shot down by NMI 357e52347bdSJani Nikula 358e52347bdSJani Nikula autoconf= [IPV6] 35919093313SMauro Carvalho Chehab See Documentation/networking/ipv6.rst. 360e52347bdSJani Nikula 361e52347bdSJani Nikula show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller 362e52347bdSJani Nikula Limit apic dumping. The parameter defines the maximal 363e52347bdSJani Nikula number of local apics being dumped. Also it is possible 364e52347bdSJani Nikula to set it to "all" by meaning -- no limit here. 365e52347bdSJani Nikula Format: { 1 (default) | 2 | ... | all }. 366e52347bdSJani Nikula The parameter valid if only apic=debug or 367e52347bdSJani Nikula apic=verbose is specified. 368e52347bdSJani Nikula Example: apic=debug show_lapic=all 369e52347bdSJani Nikula 370e52347bdSJani Nikula apm= [APM] Advanced Power Management 371e52347bdSJani Nikula See header of arch/x86/kernel/apm_32.c. 372e52347bdSJani Nikula 373e52347bdSJani Nikula arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards 374e52347bdSJani Nikula Format: <io>,<irq>,<nodeID> 375e52347bdSJani Nikula 37693ad55b7SMarc Zyngier arm64.nobti [ARM64] Unconditionally disable Branch Target 37793ad55b7SMarc Zyngier Identification support 37893ad55b7SMarc Zyngier 379f8da5752SMarc Zyngier arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication 380f8da5752SMarc Zyngier support 381f8da5752SMarc Zyngier 382e52347bdSJani Nikula ataflop= [HW,M68k] 383e52347bdSJani Nikula 384e52347bdSJani Nikula atarimouse= [HW,MOUSE] Atari Mouse 385e52347bdSJani Nikula 386e52347bdSJani Nikula atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, 387e52347bdSJani Nikula EzKey and similar keyboards 388e52347bdSJani Nikula 389e52347bdSJani Nikula atkbd.reset= [HW] Reset keyboard during initialization 390e52347bdSJani Nikula 391e52347bdSJani Nikula atkbd.set= [HW] Select keyboard code set 392e52347bdSJani Nikula Format: <int> (2 = AT (default), 3 = PS/2) 393e52347bdSJani Nikula 394e52347bdSJani Nikula atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar 395e52347bdSJani Nikula keyboards 396e52347bdSJani Nikula 397e52347bdSJani Nikula atkbd.softraw= [HW] Choose between synthetic and real raw mode 398e52347bdSJani Nikula Format: <bool> (0 = real, 1 = synthetic (default)) 399e52347bdSJani Nikula 400e52347bdSJani Nikula atkbd.softrepeat= [HW] 401e52347bdSJani Nikula Use software keyboard repeat 402e52347bdSJani Nikula 403e52347bdSJani Nikula audit= [KNL] Enable the audit sub-system 40411dd2666SGreg Edwards Format: { "0" | "1" | "off" | "on" } 40511dd2666SGreg Edwards 0 | off - kernel audit is disabled and can not be 40611dd2666SGreg Edwards enabled until the next reboot 407e52347bdSJani Nikula unset - kernel audit is initialized but disabled and 408e52347bdSJani Nikula will be fully enabled by the userspace auditd. 40911dd2666SGreg Edwards 1 | on - kernel audit is initialized and partially 41011dd2666SGreg Edwards enabled, storing at most audit_backlog_limit 41111dd2666SGreg Edwards messages in RAM until it is fully enabled by the 41211dd2666SGreg Edwards userspace auditd. 413e52347bdSJani Nikula Default: unset 414e52347bdSJani Nikula 415e52347bdSJani Nikula audit_backlog_limit= [KNL] Set the audit queue size limit. 416e52347bdSJani Nikula Format: <int> (must be >=0) 417e52347bdSJani Nikula Default: 64 418e52347bdSJani Nikula 419e52347bdSJani Nikula bau= [X86_UV] Enable the BAU on SGI UV. The default 420e52347bdSJani Nikula behavior is to disable the BAU (i.e. bau=0). 421e52347bdSJani Nikula Format: { "0" | "1" } 422e52347bdSJani Nikula 0 - Disable the BAU. 423e52347bdSJani Nikula 1 - Enable the BAU. 424e52347bdSJani Nikula unset - Disable the BAU. 425e52347bdSJani Nikula 426e52347bdSJani Nikula baycom_epp= [HW,AX25] 427e52347bdSJani Nikula Format: <io>,<mode> 428e52347bdSJani Nikula 429e52347bdSJani Nikula baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem 430e52347bdSJani Nikula Format: <io>,<mode> 431e52347bdSJani Nikula See header of drivers/net/hamradio/baycom_par.c. 432e52347bdSJani Nikula 433e52347bdSJani Nikula baycom_ser_fdx= [HW,AX25] 434e52347bdSJani Nikula BayCom Serial Port AX.25 Modem (Full Duplex Mode) 435e52347bdSJani Nikula Format: <io>,<irq>,<mode>[,<baud>] 436e52347bdSJani Nikula See header of drivers/net/hamradio/baycom_ser_fdx.c. 437e52347bdSJani Nikula 438e52347bdSJani Nikula baycom_ser_hdx= [HW,AX25] 439e52347bdSJani Nikula BayCom Serial Port AX.25 Modem (Half Duplex Mode) 440e52347bdSJani Nikula Format: <io>,<irq>,<mode> 441e52347bdSJani Nikula See header of drivers/net/hamradio/baycom_ser_hdx.c. 442e52347bdSJani Nikula 443e52347bdSJani Nikula blkdevparts= Manual partition parsing of block device(s) for 444e52347bdSJani Nikula embedded devices based on command line input. 445898bd37aSMauro Carvalho Chehab See Documentation/block/cmdline-partition.rst 446e52347bdSJani Nikula 447e52347bdSJani Nikula boot_delay= Milliseconds to delay each printk during boot. 448e52347bdSJani Nikula Values larger than 10 seconds (10000) are changed to 449e52347bdSJani Nikula no delay (0). 450e52347bdSJani Nikula Format: integer 451e52347bdSJani Nikula 4527495e092SSteven Rostedt (VMware) bootconfig [KNL] 4537495e092SSteven Rostedt (VMware) Extended command line options can be added to an initrd 4547495e092SSteven Rostedt (VMware) and this will cause the kernel to look for it. 4557495e092SSteven Rostedt (VMware) 4567495e092SSteven Rostedt (VMware) See Documentation/admin-guide/bootconfig.rst 4577495e092SSteven Rostedt (VMware) 458e52347bdSJani Nikula bert_disable [ACPI] 459e52347bdSJani Nikula Disable BERT OS support on buggy BIOSes. 460e52347bdSJani Nikula 4611ffb8d03SAlex Hung bgrt_disable [ACPI][X86] 4621ffb8d03SAlex Hung Disable BGRT to avoid flickering OEM logo. 4631ffb8d03SAlex Hung 464e52347bdSJani Nikula bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) 465e52347bdSJani Nikula bttv.radio= Most important insmod options are available as 466e52347bdSJani Nikula kernel args too. 46732e2eae2SMauro Carvalho Chehab bttv.pll= See Documentation/admin-guide/media/bttv.rst 468e52347bdSJani Nikula bttv.tuner= 469e52347bdSJani Nikula 470e52347bdSJani Nikula bulk_remove=off [PPC] This parameter disables the use of the pSeries 471e52347bdSJani Nikula firmware feature for flushing multiple hpte entries 472e52347bdSJani Nikula at a time. 473e52347bdSJani Nikula 474e52347bdSJani Nikula c101= [NET] Moxa C101 synchronous serial card 475e52347bdSJani Nikula 476e52347bdSJani Nikula cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. 477e52347bdSJani Nikula Sometimes CPU hardware bugs make them report the cache 478e52347bdSJani Nikula size incorrectly. The kernel will attempt work arounds 479e52347bdSJani Nikula to fix known problems, but for some CPUs it is not 480e52347bdSJani Nikula possible to determine what the correct size should be. 481e52347bdSJani Nikula This option provides an override for these situations. 482e52347bdSJani Nikula 4833fc46fc9SMartin Kepplinger carrier_timeout= 4843fc46fc9SMartin Kepplinger [NET] Specifies amount of time (in seconds) that 4853fc46fc9SMartin Kepplinger the kernel should wait for a network carrier. By default 4863fc46fc9SMartin Kepplinger it waits 120 seconds. 4873fc46fc9SMartin Kepplinger 488e52347bdSJani Nikula ca_keys= [KEYS] This parameter identifies a specific key(s) on 489e52347bdSJani Nikula the system trusted keyring to be used for certificate 490e52347bdSJani Nikula trust validation. 491e52347bdSJani Nikula format: { id:<keyid> | builtin } 492e52347bdSJani Nikula 493e52347bdSJani Nikula cca= [MIPS] Override the kernel pages' cache coherency 494e52347bdSJani Nikula algorithm. Accepted values range from 0 to 7 495e52347bdSJani Nikula inclusive. See arch/mips/include/asm/pgtable-bits.h 496e52347bdSJani Nikula for platform specific values (SB1, Loongson3 and 497e52347bdSJani Nikula others). 498e52347bdSJani Nikula 499e52347bdSJani Nikula ccw_timeout_log [S390] 5008b4a503dSMauro Carvalho Chehab See Documentation/s390/common_io.rst for details. 501e52347bdSJani Nikula 502e52347bdSJani Nikula cgroup_disable= [KNL] Disable a particular controller 503e52347bdSJani Nikula Format: {name of the controller(s) to disable} 504e52347bdSJani Nikula The effects of cgroup_disable=foo are: 505e52347bdSJani Nikula - foo isn't auto-mounted if you mount all cgroups in 506e52347bdSJani Nikula a single hierarchy 507e52347bdSJani Nikula - foo isn't visible as an individually mountable 508e52347bdSJani Nikula subsystem 509e52347bdSJani Nikula {Currently only "memory" controller deal with this and 510e52347bdSJani Nikula cut the overhead, others just disable the usage. So 511e52347bdSJani Nikula only cgroup_disable=memory is actually worthy} 512e52347bdSJani Nikula 5133fc9c12dSTejun Heo cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1 5143fc9c12dSTejun Heo Format: { { controller | "all" | "named" } 5153fc9c12dSTejun Heo [,{ controller | "all" | "named" }...] } 516e52347bdSJani Nikula Like cgroup_disable, but only applies to cgroup v1; 517e52347bdSJani Nikula the blacklisted controllers remain available in cgroup2. 5183fc9c12dSTejun Heo "all" blacklists all controllers and "named" disables 5193fc9c12dSTejun Heo named mounts. Specifying both "all" and "named" disables 5203fc9c12dSTejun Heo all v1 hierarchies. 521e52347bdSJani Nikula 522e52347bdSJani Nikula cgroup.memory= [KNL] Pass options to the cgroup memory controller. 523e52347bdSJani Nikula Format: <string> 524e52347bdSJani Nikula nosocket -- Disable socket memory accounting. 525e52347bdSJani Nikula nokmem -- Disable kernel memory accounting. 526e52347bdSJani Nikula 527e52347bdSJani Nikula checkreqprot [SELINUX] Set initial checkreqprot flag value. 528e52347bdSJani Nikula Format: { "0" | "1" } 529e52347bdSJani Nikula See security/selinux/Kconfig help text. 530e52347bdSJani Nikula 0 -- check protection applied by kernel (includes 531e52347bdSJani Nikula any implied execute protection). 532e52347bdSJani Nikula 1 -- check protection requested by application. 533e52347bdSJani Nikula Default value is set via a kernel config option. 534e52347bdSJani Nikula Value can be changed at runtime via 535d41415ebSStephen Smalley /sys/fs/selinux/checkreqprot. 536e9c38f9fSStephen Smalley Setting checkreqprot to 1 is deprecated. 537e52347bdSJani Nikula 538e52347bdSJani Nikula cio_ignore= [S390] 5398b4a503dSMauro Carvalho Chehab See Documentation/s390/common_io.rst for details. 540e52347bdSJani Nikula clk_ignore_unused 541e52347bdSJani Nikula [CLK] 542e52347bdSJani Nikula Prevents the clock framework from automatically gating 543e52347bdSJani Nikula clocks that have not been explicitly enabled by a Linux 544e52347bdSJani Nikula device driver but are enabled in hardware at reset or 545e52347bdSJani Nikula by the bootloader/firmware. Note that this does not 546e52347bdSJani Nikula force such clocks to be always-on nor does it reserve 547e52347bdSJani Nikula those clocks in any way. This parameter is useful for 548e52347bdSJani Nikula debug and development, but should not be needed on a 549e52347bdSJani Nikula platform with proper driver support. For more 55018bcaa4eSMauro Carvalho Chehab information, see Documentation/driver-api/clk.rst. 551e52347bdSJani Nikula 552e52347bdSJani Nikula clock= [BUGS=X86-32, HW] gettimeofday clocksource override. 553e52347bdSJani Nikula [Deprecated] 554e52347bdSJani Nikula Forces specified clocksource (if available) to be used 555e52347bdSJani Nikula when calculating gettimeofday(). If specified 556e52347bdSJani Nikula clocksource is not available, it defaults to PIT. 557e52347bdSJani Nikula Format: { pit | tsc | cyclone | pmtmr } 558e52347bdSJani Nikula 559e52347bdSJani Nikula clocksource= Override the default clocksource 560e52347bdSJani Nikula Format: <string> 561e52347bdSJani Nikula Override the default clocksource and use the clocksource 562e52347bdSJani Nikula with the name specified. 563e52347bdSJani Nikula Some clocksource names to choose from, depending on 564e52347bdSJani Nikula the platform: 565e52347bdSJani Nikula [all] jiffies (this is the base, fallback clocksource) 566e52347bdSJani Nikula [ACPI] acpi_pm 567e52347bdSJani Nikula [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, 568e52347bdSJani Nikula pxa_timer,timer3,32k_counter,timer0_1 569e52347bdSJani Nikula [X86-32] pit,hpet,tsc; 570e52347bdSJani Nikula scx200_hrt on Geode; cyclone on IBM x440 571e52347bdSJani Nikula [MIPS] MIPS 572e52347bdSJani Nikula [PARISC] cr16 573e52347bdSJani Nikula [S390] tod 574e52347bdSJani Nikula [SH] SuperH 575e52347bdSJani Nikula [SPARC64] tick 576e52347bdSJani Nikula [X86-64] hpet,tsc 577e52347bdSJani Nikula 578e52347bdSJani Nikula clocksource.arm_arch_timer.evtstrm= 579e52347bdSJani Nikula [ARM,ARM64] 580e52347bdSJani Nikula Format: <bool> 581e52347bdSJani Nikula Enable/disable the eventstream feature of the ARM 582e52347bdSJani Nikula architected timer so that code using WFE-based polling 583e52347bdSJani Nikula loops can be debugged more effectively on production 584e52347bdSJani Nikula systems. 585e52347bdSJani Nikula 5860a4bb5e5SArvind Sankar clearcpuid=BITNUM[,BITNUM...] [X86] 587e52347bdSJani Nikula Disable CPUID feature X for the kernel. See 588e52347bdSJani Nikula arch/x86/include/asm/cpufeatures.h for the valid bit 589e52347bdSJani Nikula numbers. Note the Linux specific bits are not necessarily 590e52347bdSJani Nikula stable over kernel options, but the vendor specific 591e52347bdSJani Nikula ones should be. 592e52347bdSJani Nikula Also note that user programs calling CPUID directly 593e52347bdSJani Nikula or using the feature without checking anything 594e52347bdSJani Nikula will still see it. This just prevents it from 595e52347bdSJani Nikula being used by the kernel or shown in /proc/cpuinfo. 596e52347bdSJani Nikula Also note the kernel might malfunction if you disable 597e52347bdSJani Nikula some critical bits. 598e52347bdSJani Nikula 599e52347bdSJani Nikula cma=nn[MG]@[start[MG][-end[MG]]] 600c372e741STian Tao [KNL,CMA] 601e52347bdSJani Nikula Sets the size of kernel global memory area for 602e52347bdSJani Nikula contiguous memory allocations and optionally the 603e52347bdSJani Nikula placement constraint by the physical address range of 604e52347bdSJani Nikula memory allocations. A value of 0 disables CMA 605e52347bdSJani Nikula altogether. For more information, see 6060b1abd1fSChristoph Hellwig kernel/dma/contiguous.c 607e52347bdSJani Nikula 608b7176c26SBarry Song cma_pernuma=nn[MG] 609bc47190dSRandy Dunlap [ARM64,KNL,CMA] 610b7176c26SBarry Song Sets the size of kernel per-numa memory area for 611b7176c26SBarry Song contiguous memory allocations. A value of 0 disables 612b7176c26SBarry Song per-numa CMA altogether. And If this option is not 613b7176c26SBarry Song specificed, the default value is 0. 614b7176c26SBarry Song With per-numa CMA enabled, DMA users on node nid will 615b7176c26SBarry Song first try to allocate buffer from the pernuma area 616b7176c26SBarry Song which is located in node nid, if the allocation fails, 617b7176c26SBarry Song they will fallback to the global default memory area. 618e52347bdSJani Nikula 619e52347bdSJani Nikula cmo_free_hint= [PPC] Format: { yes | no } 620e52347bdSJani Nikula Specify whether pages are marked as being inactive 621e52347bdSJani Nikula when they are freed. This is used in CMO environments 622e52347bdSJani Nikula to determine OS memory pressure for page stealing by 623e52347bdSJani Nikula a hypervisor. 624e52347bdSJani Nikula Default: yes 625e52347bdSJani Nikula 626e52347bdSJani Nikula coherent_pool=nn[KMG] [ARM,KNL] 627e52347bdSJani Nikula Sets the size of memory pool for coherent, atomic dma 628e52347bdSJani Nikula allocations, by default set to 256K. 629e52347bdSJani Nikula 630e52347bdSJani Nikula com20020= [HW,NET] ARCnet - COM20020 chipset 631e52347bdSJani Nikula Format: 632e52347bdSJani Nikula <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 633e52347bdSJani Nikula 634e52347bdSJani Nikula com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) 635e52347bdSJani Nikula Format: <io>[,<irq>] 636e52347bdSJani Nikula 637e52347bdSJani Nikula com90xx= [HW,NET] 638e52347bdSJani Nikula ARCnet - COM90xx chipset (memory-mapped buffers) 639e52347bdSJani Nikula Format: <io>[,<irq>[,<memstart>]] 640e52347bdSJani Nikula 641e52347bdSJani Nikula condev= [HW,S390] console device 642e52347bdSJani Nikula conmode= 643e52347bdSJani Nikula 644e52347bdSJani Nikula console= [KNL] Output console device and options. 645e52347bdSJani Nikula 646e52347bdSJani Nikula tty<n> Use the virtual console device <n>. 647e52347bdSJani Nikula 648e52347bdSJani Nikula ttyS<n>[,options] 649e52347bdSJani Nikula ttyUSB0[,options] 650e52347bdSJani Nikula Use the specified serial port. The options are of 651e52347bdSJani Nikula the form "bbbbpnf", where "bbbb" is the baud rate, 652e52347bdSJani Nikula "p" is parity ("n", "o", or "e"), "n" is number of 653e52347bdSJani Nikula bits, and "f" is flow control ("r" for RTS or 654e52347bdSJani Nikula omit it). Default is "9600n8". 655e52347bdSJani Nikula 656e52347bdSJani Nikula See Documentation/admin-guide/serial-console.rst for more 657e52347bdSJani Nikula information. See 658d9d6ef25SMauro Carvalho Chehab Documentation/networking/netconsole.rst for an 659e52347bdSJani Nikula alternative. 660e52347bdSJani Nikula 661e52347bdSJani Nikula uart[8250],io,<addr>[,options] 662e52347bdSJani Nikula uart[8250],mmio,<addr>[,options] 663e52347bdSJani Nikula uart[8250],mmio16,<addr>[,options] 664e52347bdSJani Nikula uart[8250],mmio32,<addr>[,options] 665e52347bdSJani Nikula uart[8250],0x<addr>[,options] 666e52347bdSJani Nikula Start an early, polled-mode console on the 8250/16550 667e52347bdSJani Nikula UART at the specified I/O port or MMIO address, 668e52347bdSJani Nikula switching to the matching ttyS device later. 669e52347bdSJani Nikula MMIO inter-register address stride is either 8-bit 670e52347bdSJani Nikula (mmio), 16-bit (mmio16), or 32-bit (mmio32). 671e52347bdSJani Nikula If none of [io|mmio|mmio16|mmio32], <addr> is assumed 672e52347bdSJani Nikula to be equivalent to 'mmio'. 'options' are specified in 673e52347bdSJani Nikula the same format described for ttyS above; if unspecified, 674e52347bdSJani Nikula the h/w is not re-initialized. 675e52347bdSJani Nikula 676e52347bdSJani Nikula hvc<n> Use the hypervisor console device <n>. This is for 677e52347bdSJani Nikula both Xen and PowerPC hypervisors. 678e52347bdSJani Nikula 679e52347bdSJani Nikula If the device connected to the port is not a TTY but a braille 680e52347bdSJani Nikula device, prepend "brl," before the device type, for instance 681e52347bdSJani Nikula console=brl,ttyS0 682e52347bdSJani Nikula For now, only VisioBraille is supported. 683e52347bdSJani Nikula 684cca10d58SSergey Senozhatsky console_msg_format= 685cca10d58SSergey Senozhatsky [KNL] Change console messages format 686cca10d58SSergey Senozhatsky default 687cca10d58SSergey Senozhatsky By default we print messages on consoles in 688cca10d58SSergey Senozhatsky "[time stamp] text\n" format (time stamp may not be 689cca10d58SSergey Senozhatsky printed, depending on CONFIG_PRINTK_TIME or 690cca10d58SSergey Senozhatsky `printk_time' param). 691cca10d58SSergey Senozhatsky syslog 692cca10d58SSergey Senozhatsky Switch to syslog format: "<%u>[time stamp] text\n" 693cca10d58SSergey Senozhatsky IOW, each message will have a facility and loglevel 694cca10d58SSergey Senozhatsky prefix. The format is similar to one used by syslog() 695cca10d58SSergey Senozhatsky syscall, or to executing "dmesg -S --raw" or to reading 696cca10d58SSergey Senozhatsky from /proc/kmsg. 697cca10d58SSergey Senozhatsky 698e52347bdSJani Nikula consoleblank= [KNL] The console blank (screen saver) timeout in 699ac0a314cSDaniel Xu seconds. A value of 0 disables the blank timer. 700ac0a314cSDaniel Xu Defaults to 0. 701e52347bdSJani Nikula 702e52347bdSJani Nikula coredump_filter= 703e52347bdSJani Nikula [KNL] Change the default value for 704e52347bdSJani Nikula /proc/<pid>/coredump_filter. 705cd4ca341SJimmy Assarsson See also Documentation/filesystems/proc.rst. 706e52347bdSJani Nikula 70762a31ce1SLeo Yan coresight_cpu_debug.enable 70862a31ce1SLeo Yan [ARM,ARM64] 70962a31ce1SLeo Yan Format: <bool> 71062a31ce1SLeo Yan Enable/disable the CPU sampling based debugging. 71162a31ce1SLeo Yan 0: default value, disable debugging 71262a31ce1SLeo Yan 1: enable debugging at boot time 71362a31ce1SLeo Yan 714e52347bdSJani Nikula cpuidle.off=1 [CPU_IDLE] 715e52347bdSJani Nikula disable the cpuidle sub-system 716e52347bdSJani Nikula 71761cb5758SRafael J. Wysocki cpuidle.governor= 71861cb5758SRafael J. Wysocki [CPU_IDLE] Name of the cpuidle governor to use. 71961cb5758SRafael J. Wysocki 720d82f2692SLen Brown cpufreq.off=1 [CPU_FREQ] 721d82f2692SLen Brown disable the cpufreq sub-system 722d82f2692SLen Brown 7238412b456SQuentin Perret cpufreq.default_governor= 7248412b456SQuentin Perret [CPU_FREQ] Name of the default cpufreq governor or 7258412b456SQuentin Perret policy to use. This governor must be registered in the 7268412b456SQuentin Perret kernel before the cpufreq driver probes. 7278412b456SQuentin Perret 728e52347bdSJani Nikula cpu_init_udelay=N 729e52347bdSJani Nikula [X86] Delay for N microsec between assert and de-assert 730e52347bdSJani Nikula of APIC INIT to start processors. This delay occurs 731e52347bdSJani Nikula on every CPU online, such as boot, and resume from suspend. 732e52347bdSJani Nikula Default: 10000 733e52347bdSJani Nikula 734e52347bdSJani Nikula cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 735e52347bdSJani Nikula Format: 736e52347bdSJani Nikula <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 737e52347bdSJani Nikula 738e52347bdSJani Nikula crashkernel=size[KMG][@offset[KMG]] 739e52347bdSJani Nikula [KNL] Using kexec, Linux can switch to a 'crash kernel' 740e52347bdSJani Nikula upon panic. This parameter reserves the physical 741e52347bdSJani Nikula memory region [offset, offset + size] for that kernel 742e52347bdSJani Nikula image. If '@offset' is omitted, then a suitable offset 743b9ac3849SDave Young is selected automatically. 744be3a5b0eSRandy Dunlap [KNL, X86-64] Select a region under 4G first, and 745b9ac3849SDave Young fall back to reserve region above 4G when '@offset' 746b9ac3849SDave Young hasn't been specified. 747330d4810SMauro Carvalho Chehab See Documentation/admin-guide/kdump/kdump.rst for further details. 748e52347bdSJani Nikula 749e52347bdSJani Nikula crashkernel=range1:size1[,range2:size2,...][@offset] 750e52347bdSJani Nikula [KNL] Same as above, but depends on the memory 751e52347bdSJani Nikula in the running system. The syntax of range is 752e52347bdSJani Nikula start-[end] where start and end are both 753e52347bdSJani Nikula a memory unit (amount[KMG]). See also 754330d4810SMauro Carvalho Chehab Documentation/admin-guide/kdump/kdump.rst for an example. 755e52347bdSJani Nikula 756e52347bdSJani Nikula crashkernel=size[KMG],high 757be3a5b0eSRandy Dunlap [KNL, X86-64] range could be above 4G. Allow kernel 758e52347bdSJani Nikula to allocate physical memory region from top, so could 759e52347bdSJani Nikula be above 4G if system have more than 4G ram installed. 760e52347bdSJani Nikula Otherwise memory region will be allocated below 4G, if 761e52347bdSJani Nikula available. 762e52347bdSJani Nikula It will be ignored if crashkernel=X is specified. 763e52347bdSJani Nikula crashkernel=size[KMG],low 764be3a5b0eSRandy Dunlap [KNL, X86-64] range under 4G. When crashkernel=X,high 765e52347bdSJani Nikula is passed, kernel could allocate physical memory region 766e52347bdSJani Nikula above 4G, that cause second kernel crash on system 767e52347bdSJani Nikula that require some amount of low memory, e.g. swiotlb 768e52347bdSJani Nikula requires at least 64M+32K low memory, also enough extra 769e52347bdSJani Nikula low memory is needed to make sure DMA buffers for 32-bit 770e52347bdSJani Nikula devices won't run out. Kernel would try to allocate at 771e52347bdSJani Nikula at least 256M below 4G automatically. 772e52347bdSJani Nikula This one let user to specify own low range under 4G 773e52347bdSJani Nikula for second kernel instead. 774e52347bdSJani Nikula 0: to disable low allocation. 775e52347bdSJani Nikula It will be ignored when crashkernel=X,high is not used 776e52347bdSJani Nikula or memory reserved is below 4G. 777e52347bdSJani Nikula 778e52347bdSJani Nikula cryptomgr.notests 779e52347bdSJani Nikula [KNL] Disable crypto self-tests 780e52347bdSJani Nikula 781e52347bdSJani Nikula cs89x0_dma= [HW,NET] 782e52347bdSJani Nikula Format: <dma> 783e52347bdSJani Nikula 784e52347bdSJani Nikula cs89x0_media= [HW,NET] 785e52347bdSJani Nikula Format: { rj45 | aui | bnc } 786e52347bdSJani Nikula 7878d0968ccSJuergen Gross csdlock_debug= [KNL] Enable debug add-ons of cross-CPU function call 7888d0968ccSJuergen Gross handling. When switched on, additional debug data is 7898d0968ccSJuergen Gross printed to the console in case a hanging CPU is 7908d0968ccSJuergen Gross detected, and that CPU is pinged again in order to try 7918d0968ccSJuergen Gross to resolve the hang situation. 792*a5aabaceSJuergen Gross 0: disable csdlock debugging (default) 793*a5aabaceSJuergen Gross 1: enable basic csdlock debugging (minor impact) 794*a5aabaceSJuergen Gross ext: enable extended csdlock debugging (more impact, 795*a5aabaceSJuergen Gross but more data) 7968d0968ccSJuergen Gross 797e52347bdSJani Nikula dasd= [HW,NET] 798e52347bdSJani Nikula See header of drivers/s390/block/dasd_devmap.c. 799e52347bdSJani Nikula 800e52347bdSJani Nikula db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port 801e52347bdSJani Nikula (one device per port) 802e52347bdSJani Nikula Format: <port#>,<type> 8031752118dSTom Saeger See also Documentation/input/devices/joystick-parport.rst 804e52347bdSJani Nikula 805e52347bdSJani Nikula ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot 806787e3075SSteffen Maier time. See 807787e3075SSteffen Maier Documentation/admin-guide/dynamic-debug-howto.rst for 808e52347bdSJani Nikula details. Deprecated, see dyndbg. 809e52347bdSJani Nikula 810e52347bdSJani Nikula debug [KNL] Enable kernel debugging (events log level). 811e52347bdSJani Nikula 8123672476eSTobin C. Harding debug_boot_weak_hash 8133672476eSTobin C. Harding [KNL] Enable printing [hashed] pointers early in the 8143672476eSTobin C. Harding boot sequence. If enabled, we use a weak hash instead 8153672476eSTobin C. Harding of siphash to hash pointers. Use this option if you are 8163672476eSTobin C. Harding seeing instances of '(___ptrval___)') and need to see a 8173672476eSTobin C. Harding value (hashed pointer) instead. Cryptographically 8183672476eSTobin C. Harding insecure, please do not use on production kernels. 8193672476eSTobin C. Harding 820e52347bdSJani Nikula debug_locks_verbose= 8215831c0f7SPeter Zijlstra [KNL] verbose locking self-tests 8225831c0f7SPeter Zijlstra Format: <int> 823e52347bdSJani Nikula Print debugging info while doing the locking API 824e52347bdSJani Nikula self-tests. 8255831c0f7SPeter Zijlstra Bitmask for the various LOCKTYPE_ tests. Defaults to 0 8265831c0f7SPeter Zijlstra (no extra messages), setting it to -1 (all bits set) 8275831c0f7SPeter Zijlstra will print _a_lot_ more information - normally only 8285831c0f7SPeter Zijlstra useful to lockdep developers. 829e52347bdSJani Nikula 830e52347bdSJani Nikula debug_objects [KNL] Enable object debugging 831e52347bdSJani Nikula 832e52347bdSJani Nikula no_debug_objects 833e52347bdSJani Nikula [KNL] Disable object debugging 834e52347bdSJani Nikula 835e52347bdSJani Nikula debug_guardpage_minorder= 836e52347bdSJani Nikula [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this 837e52347bdSJani Nikula parameter allows control of the order of pages that will 838e52347bdSJani Nikula be intentionally kept free (and hence protected) by the 839e52347bdSJani Nikula buddy allocator. Bigger value increase the probability 840e52347bdSJani Nikula of catching random memory corruption, but reduce the 841e52347bdSJani Nikula amount of memory for normal system use. The maximum 842e52347bdSJani Nikula possible value is MAX_ORDER/2. Setting this parameter 843e52347bdSJani Nikula to 1 or 2 should be enough to identify most random 844e52347bdSJani Nikula memory corruption problems caused by bugs in kernel or 845e52347bdSJani Nikula driver code when a CPU writes to (or reads from) a 846e52347bdSJani Nikula random memory location. Note that there exists a class 847e52347bdSJani Nikula of memory corruptions problems caused by buggy H/W or 848e52347bdSJani Nikula F/W or by drivers badly programing DMA (basically when 849e52347bdSJani Nikula memory is written at bus level and the CPU MMU is 850e52347bdSJani Nikula bypassed) which are not detectable by 851e52347bdSJani Nikula CONFIG_DEBUG_PAGEALLOC, hence this option will not help 852e52347bdSJani Nikula tracking down these problems. 853e52347bdSJani Nikula 854e52347bdSJani Nikula debug_pagealloc= 8553972f6bbSVlastimil Babka [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this parameter 8563972f6bbSVlastimil Babka enables the feature at boot time. By default, it is 8573972f6bbSVlastimil Babka disabled and the system will work mostly the same as a 8583972f6bbSVlastimil Babka kernel built without CONFIG_DEBUG_PAGEALLOC. 8598974558fSVlastimil Babka Note: to get most of debug_pagealloc error reports, it's 8608974558fSVlastimil Babka useful to also enable the page_owner functionality. 861e52347bdSJani Nikula on: enable the feature 862e52347bdSJani Nikula 863a24c6f7bSPeter Enderborg debugfs= [KNL] This parameter enables what is exposed to userspace 864a24c6f7bSPeter Enderborg and debugfs internal clients. 865a24c6f7bSPeter Enderborg Format: { on, no-mount, off } 866a24c6f7bSPeter Enderborg on: All functions are enabled. 867a24c6f7bSPeter Enderborg no-mount: 868a24c6f7bSPeter Enderborg Filesystem is not registered but kernel clients can 869a24c6f7bSPeter Enderborg access APIs and a crashkernel can be used to read 870a24c6f7bSPeter Enderborg its content. There is nothing to mount. 871a24c6f7bSPeter Enderborg off: Filesystem is not registered and clients 872a24c6f7bSPeter Enderborg get a -EPERM as result when trying to register files 873a24c6f7bSPeter Enderborg or directories within debugfs. 874a24c6f7bSPeter Enderborg This is equivalent of the runtime functionality if 875a24c6f7bSPeter Enderborg debugfs was not enabled in the kernel at all. 876a24c6f7bSPeter Enderborg Default value is set in build-time with a kernel configuration. 877a24c6f7bSPeter Enderborg 878e52347bdSJani Nikula debugpat [X86] Enable PAT debugging 879e52347bdSJani Nikula 880e52347bdSJani Nikula decnet.addr= [HW,NET] 881e52347bdSJani Nikula Format: <area>[,<node>] 8829a69fb9cSMauro Carvalho Chehab See also Documentation/networking/decnet.rst. 883e52347bdSJani Nikula 884e52347bdSJani Nikula default_hugepagesz= 885282f4214SMike Kravetz [HW] The size of the default HugeTLB page. This is 886282f4214SMike Kravetz the size represented by the legacy /proc/ hugepages 887282f4214SMike Kravetz APIs. In addition, this is the default hugetlb size 888282f4214SMike Kravetz used for shmget(), mmap() and mounting hugetlbfs 889282f4214SMike Kravetz filesystems. If not specified, defaults to the 890282f4214SMike Kravetz architecture's default huge page size. Huge page 891282f4214SMike Kravetz sizes are architecture dependent. See also 892282f4214SMike Kravetz Documentation/admin-guide/mm/hugetlbpage.rst. 893282f4214SMike Kravetz Format: size[KMG] 894e52347bdSJani Nikula 89525b4e70dSRob Herring deferred_probe_timeout= 89625b4e70dSRob Herring [KNL] Debugging option to set a timeout in seconds for 89725b4e70dSRob Herring deferred probe to give up waiting on dependencies to 89825b4e70dSRob Herring probe. Only specific dependencies (subsystems or 89925b4e70dSRob Herring drivers) that have opted in will be ignored. A timeout of 0 90025b4e70dSRob Herring will timeout at the end of initcalls. This option will also 90125b4e70dSRob Herring dump out devices still on the deferred probe list after 90225b4e70dSRob Herring retrying. 90325b4e70dSRob Herring 904c65e6815SMikhail Zaslonko dfltcc= [HW,S390] 905c65e6815SMikhail Zaslonko Format: { on | off | def_only | inf_only | always } 906c65e6815SMikhail Zaslonko on: s390 zlib hardware support for compression on 907c65e6815SMikhail Zaslonko level 1 and decompression (default) 908c65e6815SMikhail Zaslonko off: No s390 zlib hardware support 909c65e6815SMikhail Zaslonko def_only: s390 zlib hardware support for deflate 910c65e6815SMikhail Zaslonko only (compression on level 1) 911c65e6815SMikhail Zaslonko inf_only: s390 zlib hardware support for inflate 912c65e6815SMikhail Zaslonko only (decompression) 913c65e6815SMikhail Zaslonko always: Same as 'on' but ignores the selected compression 914c65e6815SMikhail Zaslonko level always using hardware support (used for debugging) 915c65e6815SMikhail Zaslonko 916e52347bdSJani Nikula dhash_entries= [KNL] 917e52347bdSJani Nikula Set number of hash buckets for dentry cache. 918e52347bdSJani Nikula 919e52347bdSJani Nikula disable_1tb_segments [PPC] 920e52347bdSJani Nikula Disables the use of 1TB hash page table segments. This 921e52347bdSJani Nikula causes the kernel to fall back to 256MB segments which 922e52347bdSJani Nikula can be useful when debugging issues that require an SLB 923e52347bdSJani Nikula miss to occur. 924e52347bdSJani Nikula 92582a1b8edSNicholas Piggin stress_slb [PPC] 92682a1b8edSNicholas Piggin Limits the number of kernel SLB entries, and flushes 92782a1b8edSNicholas Piggin them frequently to increase the rate of SLB faults 92882a1b8edSNicholas Piggin on kernel addresses. 92982a1b8edSNicholas Piggin 930e52347bdSJani Nikula disable= [IPV6] 93119093313SMauro Carvalho Chehab See Documentation/networking/ipv6.rst. 932e52347bdSJani Nikula 933b5cb15d9SChris von Recklinghausen hardened_usercopy= 934b5cb15d9SChris von Recklinghausen [KNL] Under CONFIG_HARDENED_USERCOPY, whether 935b5cb15d9SChris von Recklinghausen hardening is enabled for this boot. Hardened 936b5cb15d9SChris von Recklinghausen usercopy checking is used to protect the kernel 937b5cb15d9SChris von Recklinghausen from reading or writing beyond known memory 938b5cb15d9SChris von Recklinghausen allocation boundaries as a proactive defense 939b5cb15d9SChris von Recklinghausen against bounds-checking flaws in the kernel's 940b5cb15d9SChris von Recklinghausen copy_to_user()/copy_from_user() interface. 941b5cb15d9SChris von Recklinghausen on Perform hardened usercopy checks (default). 942b5cb15d9SChris von Recklinghausen off Disable hardened usercopy checks. 943b5cb15d9SChris von Recklinghausen 944e52347bdSJani Nikula disable_radix [PPC] 945e52347bdSJani Nikula Disable RADIX MMU mode on POWER9 946e52347bdSJani Nikula 947bf6b7661SAneesh Kumar K.V radix_hcall_invalidate=on [PPC/PSERIES] 948bf6b7661SAneesh Kumar K.V Disable RADIX GTSE feature and use hcall for TLB 949bf6b7661SAneesh Kumar K.V invalidate. 950bf6b7661SAneesh Kumar K.V 9512275d7b5SNicholas Piggin disable_tlbie [PPC] 9522275d7b5SNicholas Piggin Disable TLBIE instruction. Currently does not work 9532275d7b5SNicholas Piggin with KVM, with HASH MMU, or with coherent accelerators. 9542275d7b5SNicholas Piggin 955e52347bdSJani Nikula disable_cpu_apicid= [X86,APIC,SMP] 956e52347bdSJani Nikula Format: <int> 957e52347bdSJani Nikula The number of initial APIC ID for the 958e52347bdSJani Nikula corresponding CPU to be disabled at boot, 959e52347bdSJani Nikula mostly used for the kdump 2nd kernel to 960e52347bdSJani Nikula disable BSP to wake up multiple CPUs without 961e52347bdSJani Nikula causing system reset or hang due to sending 962e52347bdSJani Nikula INIT from AP to BSP. 963e52347bdSJani Nikula 964e52347bdSJani Nikula disable_ddw [PPC/PSERIES] 965255bf90fSRandy Dunlap Disable Dynamic DMA Window support. Use this 966e52347bdSJani Nikula to workaround buggy firmware. 967e52347bdSJani Nikula 968e52347bdSJani Nikula disable_ipv6= [IPV6] 96919093313SMauro Carvalho Chehab See Documentation/networking/ipv6.rst. 970e52347bdSJani Nikula 971e52347bdSJani Nikula disable_mtrr_cleanup [X86] 972e52347bdSJani Nikula The kernel tries to adjust MTRR layout from continuous 973e52347bdSJani Nikula to discrete, to make X server driver able to add WB 974e52347bdSJani Nikula entry later. This parameter disables that. 975e52347bdSJani Nikula 976e52347bdSJani Nikula disable_mtrr_trim [X86, Intel and AMD only] 977e52347bdSJani Nikula By default the kernel will trim any uncacheable 978e52347bdSJani Nikula memory out of your available memory pool based on 979e52347bdSJani Nikula MTRR settings. This parameter disables that behavior, 980e52347bdSJani Nikula possibly causing your machine to run very slowly. 981e52347bdSJani Nikula 982e52347bdSJani Nikula disable_timer_pin_1 [X86] 983e52347bdSJani Nikula Disable PIN 1 of APIC timer 984e52347bdSJani Nikula Can be useful to work around chipset bugs. 985e52347bdSJani Nikula 986e52347bdSJani Nikula dis_ucode_ldr [X86] Disable the microcode loader. 987e52347bdSJani Nikula 988e52347bdSJani Nikula dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, 989e52347bdSJani Nikula this option disables the debugging code at boot. 990e52347bdSJani Nikula 991e52347bdSJani Nikula dma_debug_entries=<number> 992e52347bdSJani Nikula This option allows to tune the number of preallocated 993e52347bdSJani Nikula entries for DMA-API debugging code. One entry is 994e52347bdSJani Nikula required per DMA-API allocation. Use this if the 995e52347bdSJani Nikula DMA-API debugging code disables itself because the 996e52347bdSJani Nikula architectural default is too low. 997e52347bdSJani Nikula 998e52347bdSJani Nikula dma_debug_driver=<driver_name> 999e52347bdSJani Nikula With this option the DMA-API debugging driver 1000e52347bdSJani Nikula filter feature can be enabled at boot time. Just 1001e52347bdSJani Nikula pass the driver to filter for as the parameter. 1002e52347bdSJani Nikula The filter can be disabled or changed to another 1003e52347bdSJani Nikula driver later using sysfs. 1004e52347bdSJani Nikula 10051ea61b68SFeng Tang driver_async_probe= [KNL] 10061ea61b68SFeng Tang List of driver names to be probed asynchronously. 10071ea61b68SFeng Tang Format: <driver_name1>,<driver_name2>... 10081ea61b68SFeng Tang 100953fd40a9SJani Nikula drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] 1010e52347bdSJani Nikula Broken monitors, graphic adapters, KVMs and EDIDless 1011e52347bdSJani Nikula panels may send no or incorrect EDID data sets. 1012e52347bdSJani Nikula This parameter allows to specify an EDID data sets 1013e52347bdSJani Nikula in the /lib/firmware directory that are used instead. 1014e52347bdSJani Nikula Generic built-in EDID data sets are used, if one of 1015e52347bdSJani Nikula edid/1024x768.bin, edid/1280x1024.bin, 1016e52347bdSJani Nikula edid/1680x1050.bin, or edid/1920x1080.bin is given 1017e52347bdSJani Nikula and no file with the same name exists. Details and 1018e52347bdSJani Nikula instructions how to build your own EDID data are 1019cd4ca341SJimmy Assarsson available in Documentation/admin-guide/edid.rst. An EDID 1020e52347bdSJani Nikula data set will only be used for a particular connector, 1021e52347bdSJani Nikula if its name and a colon are prepended to the EDID 1022e52347bdSJani Nikula name. Each connector may use a unique EDID data 1023e52347bdSJani Nikula set by separating the files with a comma. An EDID 1024e52347bdSJani Nikula data set with no connector name will be used for 1025e52347bdSJani Nikula any connectors not explicitly specified. 1026e52347bdSJani Nikula 1027e52347bdSJani Nikula dscc4.setup= [NET] 1028e52347bdSJani Nikula 1029a2b05b7aSNicholas Piggin dt_cpu_ftrs= [PPC] 1030a2b05b7aSNicholas Piggin Format: {"off" | "known"} 1031a2b05b7aSNicholas Piggin Control how the dt_cpu_ftrs device-tree binding is 1032a2b05b7aSNicholas Piggin used for CPU feature discovery and setup (if it 1033a2b05b7aSNicholas Piggin exists). 1034a2b05b7aSNicholas Piggin off: Do not use it, fall back to legacy cpu table. 1035a2b05b7aSNicholas Piggin known: Do not pass through unknown features to guests 1036a2b05b7aSNicholas Piggin or userspace, only those that the kernel is aware of. 1037a2b05b7aSNicholas Piggin 1038e7aa8c2eSLinus Torvalds dump_apple_properties [X86] 1039e7aa8c2eSLinus Torvalds Dump name and content of EFI device properties on 1040e7aa8c2eSLinus Torvalds x86 Macs. Useful for driver authors to determine 1041e7aa8c2eSLinus Torvalds what data is available or for reverse-engineering. 1042e7aa8c2eSLinus Torvalds 1043e52347bdSJani Nikula dyndbg[="val"] [KNL,DYNAMIC_DEBUG] 1044307e3ee9SRandy Dunlap <module>.dyndbg[="val"] 1045e52347bdSJani Nikula Enable debug messages at boot time. See 1046787e3075SSteffen Maier Documentation/admin-guide/dynamic-debug-howto.rst 1047787e3075SSteffen Maier for details. 1048e52347bdSJani Nikula 1049e52347bdSJani Nikula nopku [X86] Disable Memory Protection Keys CPU feature found 1050e52347bdSJani Nikula in some Intel CPUs. 1051e52347bdSJani Nikula 1052307e3ee9SRandy Dunlap <module>.async_probe [KNL] 1053e52347bdSJani Nikula Enable asynchronous probe on this module. 1054e52347bdSJani Nikula 1055e52347bdSJani Nikula early_ioremap_debug [KNL] 1056e52347bdSJani Nikula Enable debug messages in early_ioremap support. This 1057e52347bdSJani Nikula is useful for tracking down temporary early mappings 1058e52347bdSJani Nikula which are not unmapped. 1059e52347bdSJani Nikula 1060e52347bdSJani Nikula earlycon= [KNL] Output early console device and options. 1061e52347bdSJani Nikula 1062e18409c0SChristoph Hellwig When used with no options, the early console is 1063e18409c0SChristoph Hellwig determined by stdout-path property in device tree's 1064e18409c0SChristoph Hellwig chosen node or the ACPI SPCR table if supported by 1065e18409c0SChristoph Hellwig the platform. 1066e52347bdSJani Nikula 1067e52347bdSJani Nikula cdns,<addr>[,options] 1068e52347bdSJani Nikula Start an early, polled-mode console on a Cadence 1069e52347bdSJani Nikula (xuartps) serial port at the specified address. Only 1070e52347bdSJani Nikula supported option is baud rate. If baud rate is not 1071e52347bdSJani Nikula specified, the serial port must already be setup and 1072e52347bdSJani Nikula configured. 1073e52347bdSJani Nikula 1074e52347bdSJani Nikula uart[8250],io,<addr>[,options] 1075e52347bdSJani Nikula uart[8250],mmio,<addr>[,options] 1076e52347bdSJani Nikula uart[8250],mmio32,<addr>[,options] 1077e52347bdSJani Nikula uart[8250],mmio32be,<addr>[,options] 1078e52347bdSJani Nikula uart[8250],0x<addr>[,options] 1079e52347bdSJani Nikula Start an early, polled-mode console on the 8250/16550 1080e52347bdSJani Nikula UART at the specified I/O port or MMIO address. 1081e52347bdSJani Nikula MMIO inter-register address stride is either 8-bit 1082e52347bdSJani Nikula (mmio) or 32-bit (mmio32 or mmio32be). 1083e52347bdSJani Nikula If none of [io|mmio|mmio32|mmio32be], <addr> is assumed 1084e52347bdSJani Nikula to be equivalent to 'mmio'. 'options' are specified 1085e52347bdSJani Nikula in the same format described for "console=ttyS<n>"; if 1086e52347bdSJani Nikula unspecified, the h/w is not initialized. 1087e52347bdSJani Nikula 1088e52347bdSJani Nikula pl011,<addr> 1089e52347bdSJani Nikula pl011,mmio32,<addr> 1090e52347bdSJani Nikula Start an early, polled-mode console on a pl011 serial 1091e52347bdSJani Nikula port at the specified address. The pl011 serial port 1092e52347bdSJani Nikula must already be setup and configured. Options are not 1093e52347bdSJani Nikula yet supported. If 'mmio32' is specified, then only 1094e52347bdSJani Nikula the driver will use only 32-bit accessors to read/write 1095e52347bdSJani Nikula the device registers. 1096e52347bdSJani Nikula 1097e52347bdSJani Nikula meson,<addr> 1098e52347bdSJani Nikula Start an early, polled-mode console on a meson serial 1099e52347bdSJani Nikula port at the specified address. The serial port must 1100e52347bdSJani Nikula already be setup and configured. Options are not yet 1101e52347bdSJani Nikula supported. 1102e52347bdSJani Nikula 1103e52347bdSJani Nikula msm_serial,<addr> 1104e52347bdSJani Nikula Start an early, polled-mode console on an msm serial 1105e52347bdSJani Nikula port at the specified address. The serial port 1106e52347bdSJani Nikula must already be setup and configured. Options are not 1107e52347bdSJani Nikula yet supported. 1108e52347bdSJani Nikula 1109e52347bdSJani Nikula msm_serial_dm,<addr> 1110e52347bdSJani Nikula Start an early, polled-mode console on an msm serial 1111e52347bdSJani Nikula dm port at the specified address. The serial port 1112e52347bdSJani Nikula must already be setup and configured. Options are not 1113e52347bdSJani Nikula yet supported. 1114e52347bdSJani Nikula 1115e36361d7SAndreas Färber owl,<addr> 1116e36361d7SAndreas Färber Start an early, polled-mode console on a serial port 1117e36361d7SAndreas Färber of an Actions Semi SoC, such as S500 or S900, at the 1118e36361d7SAndreas Färber specified address. The serial port must already be 1119e36361d7SAndreas Färber setup and configured. Options are not yet supported. 1120e36361d7SAndreas Färber 1121c10b1332SManivannan Sadhasivam rda,<addr> 1122c10b1332SManivannan Sadhasivam Start an early, polled-mode console on a serial port 1123c10b1332SManivannan Sadhasivam of an RDA Micro SoC, such as RDA8810PL, at the 1124c10b1332SManivannan Sadhasivam specified address. The serial port must already be 1125c10b1332SManivannan Sadhasivam setup and configured. Options are not yet supported. 1126c10b1332SManivannan Sadhasivam 112782f12ab3SPalmer Dabbelt sbi 112882f12ab3SPalmer Dabbelt Use RISC-V SBI (Supervisor Binary Interface) for early 112982f12ab3SPalmer Dabbelt console. 113082f12ab3SPalmer Dabbelt 1131e52347bdSJani Nikula smh Use ARM semihosting calls for early console. 1132e52347bdSJani Nikula 1133e52347bdSJani Nikula s3c2410,<addr> 1134e52347bdSJani Nikula s3c2412,<addr> 1135e52347bdSJani Nikula s3c2440,<addr> 1136e52347bdSJani Nikula s3c6400,<addr> 1137e52347bdSJani Nikula s5pv210,<addr> 1138e52347bdSJani Nikula exynos4210,<addr> 1139e52347bdSJani Nikula Use early console provided by serial driver available 1140e52347bdSJani Nikula on Samsung SoCs, requires selecting proper type and 1141e52347bdSJani Nikula a correct base address of the selected UART port. The 1142e52347bdSJani Nikula serial port must already be setup and configured. 1143e52347bdSJani Nikula Options are not yet supported. 1144e52347bdSJani Nikula 1145ec84aa0aSMartin Blumenstingl lantiq,<addr> 1146ec84aa0aSMartin Blumenstingl Start an early, polled-mode console on a lantiq serial 1147ec84aa0aSMartin Blumenstingl (lqasc) port at the specified address. The serial port 1148ec84aa0aSMartin Blumenstingl must already be setup and configured. Options are not 1149ec84aa0aSMartin Blumenstingl yet supported. 1150ec84aa0aSMartin Blumenstingl 1151e52347bdSJani Nikula lpuart,<addr> 1152e52347bdSJani Nikula lpuart32,<addr> 1153e52347bdSJani Nikula Use early console provided by Freescale LP UART driver 1154e52347bdSJani Nikula found on Freescale Vybrid and QorIQ LS1021A processors. 1155e52347bdSJani Nikula A valid base address must be provided, and the serial 1156e52347bdSJani Nikula port must already be setup and configured. 1157e52347bdSJani Nikula 11587fe068dbSJonathan Neuschäfer ec_imx21,<addr> 11597fe068dbSJonathan Neuschäfer ec_imx6q,<addr> 11607fe068dbSJonathan Neuschäfer Start an early, polled-mode, output-only console on the 11617fe068dbSJonathan Neuschäfer Freescale i.MX UART at the specified address. The UART 11627fe068dbSJonathan Neuschäfer must already be setup and configured. 11637fe068dbSJonathan Neuschäfer 1164f7c864e7SAndre Przywara ar3700_uart,<addr> 1165e52347bdSJani Nikula Start an early, polled-mode console on the 1166e52347bdSJani Nikula Armada 3700 serial port at the specified 1167e52347bdSJani Nikula address. The serial port must already be setup 1168e52347bdSJani Nikula and configured. Options are not yet supported. 1169e52347bdSJani Nikula 117043f1831bSKarthikeyan Ramasubramanian qcom_geni,<addr> 117143f1831bSKarthikeyan Ramasubramanian Start an early, polled-mode console on a Qualcomm 117243f1831bSKarthikeyan Ramasubramanian Generic Interface (GENI) based serial port at the 117343f1831bSKarthikeyan Ramasubramanian specified address. The serial port must already be 117443f1831bSKarthikeyan Ramasubramanian setup and configured. Options are not yet supported. 117543f1831bSKarthikeyan Ramasubramanian 117669c1f396SArd Biesheuvel efifb,[options] 117769c1f396SArd Biesheuvel Start an early, unaccelerated console on the EFI 117869c1f396SArd Biesheuvel memory mapped framebuffer (if available). On cache 117969c1f396SArd Biesheuvel coherent non-x86 systems that use system memory for 118069c1f396SArd Biesheuvel the framebuffer, pass the 'ram' option so that it is 118169c1f396SArd Biesheuvel mapped with the correct attributes. 118269c1f396SArd Biesheuvel 118309864c1cSStefan-gabriel Mirea linflex,<addr> 11849905f32aSStefan-Gabriel Mirea Use early console provided by Freescale LINFlexD UART 118509864c1cSStefan-gabriel Mirea serial driver for NXP S32V234 SoCs. A valid base 118609864c1cSStefan-gabriel Mirea address must be provided, and the serial port must 118709864c1cSStefan-gabriel Mirea already be setup and configured. 118809864c1cSStefan-gabriel Mirea 11894ba66a97SArnd Bergmann earlyprintk= [X86,SH,ARM,M68k,S390] 1190e52347bdSJani Nikula earlyprintk=vga 119189175cf7SHeiko Carstens earlyprintk=sclp 1192e52347bdSJani Nikula earlyprintk=xen 1193e52347bdSJani Nikula earlyprintk=serial[,ttySn[,baudrate]] 1194e52347bdSJani Nikula earlyprintk=serial[,0x...[,baudrate]] 1195e52347bdSJani Nikula earlyprintk=ttySn[,baudrate] 1196e52347bdSJani Nikula earlyprintk=dbgp[debugController#] 1197d2266bbfSFeng Tang earlyprintk=pciserial[,force],bus:device.function[,baudrate] 11981b5aeebfSLu Baolu earlyprintk=xdbc[xhciController#] 1199e52347bdSJani Nikula 1200e52347bdSJani Nikula earlyprintk is useful when the kernel crashes before 1201e52347bdSJani Nikula the normal console is initialized. It is not enabled by 1202e52347bdSJani Nikula default because it has some cosmetic problems. 1203e52347bdSJani Nikula 1204e52347bdSJani Nikula Append ",keep" to not disable it when the real console 1205e52347bdSJani Nikula takes over. 1206e52347bdSJani Nikula 1207e52347bdSJani Nikula Only one of vga, efi, serial, or usb debug port can 1208e52347bdSJani Nikula be used at a time. 1209e52347bdSJani Nikula 1210e52347bdSJani Nikula Currently only ttyS0 and ttyS1 may be specified by 1211e52347bdSJani Nikula name. Other I/O ports may be explicitly specified 1212e52347bdSJani Nikula on some architectures (x86 and arm at least) by 1213e52347bdSJani Nikula replacing ttySn with an I/O port address, like this: 1214e52347bdSJani Nikula earlyprintk=serial,0x1008,115200 1215e52347bdSJani Nikula You can find the port for a given device in 1216e52347bdSJani Nikula /proc/tty/driver/serial: 1217e52347bdSJani Nikula 2: uart:ST16650V2 port:00001008 irq:18 ... 1218e52347bdSJani Nikula 1219e52347bdSJani Nikula Interaction with the standard serial driver is not 1220e52347bdSJani Nikula very good. 1221e52347bdSJani Nikula 1222e52347bdSJani Nikula The VGA and EFI output is eventually overwritten by 1223e52347bdSJani Nikula the real console. 1224e52347bdSJani Nikula 1225e52347bdSJani Nikula The xen output can only be used by Xen PV guests. 1226e52347bdSJani Nikula 122789175cf7SHeiko Carstens The sclp output can only be used on s390. 122889175cf7SHeiko Carstens 1229d2266bbfSFeng Tang The optional "force" to "pciserial" enables use of a 1230d2266bbfSFeng Tang PCI device even when its classcode is not of the 1231d2266bbfSFeng Tang UART class. 1232d2266bbfSFeng Tang 1233e52347bdSJani Nikula edac_report= [HW,EDAC] Control how to report EDAC event 1234e52347bdSJani Nikula Format: {"on" | "off" | "force"} 1235e52347bdSJani Nikula on: enable EDAC to report H/W event. May be overridden 1236e52347bdSJani Nikula by other higher priority error reporting module. 1237e52347bdSJani Nikula off: disable H/W event reporting through EDAC. 1238e52347bdSJani Nikula force: enforce the use of EDAC to report H/W event. 1239e52347bdSJani Nikula default: on. 1240e52347bdSJani Nikula 1241e52347bdSJani Nikula ekgdboc= [X86,KGDB] Allow early kernel console debugging 1242e52347bdSJani Nikula ekgdboc=kbd 1243e52347bdSJani Nikula 1244e52347bdSJani Nikula This is designed to be used in conjunction with 1245e52347bdSJani Nikula the boot argument: earlyprintk=vga 1246e52347bdSJani Nikula 1247f71fc3bcSDouglas Anderson This parameter works in place of the kgdboc parameter 1248f71fc3bcSDouglas Anderson but can only be used if the backing tty is available 1249f71fc3bcSDouglas Anderson very early in the boot process. For early debugging 1250f71fc3bcSDouglas Anderson via a serial port see kgdboc_earlycon instead. 1251f71fc3bcSDouglas Anderson 1252e52347bdSJani Nikula edd= [EDD] 1253e52347bdSJani Nikula Format: {"off" | "on" | "skip[mbr]"} 1254e52347bdSJani Nikula 1255e52347bdSJani Nikula efi= [EFI] 1256c03f739fSHeinrich Schuchardt Format: { "debug", "disable_early_pci_dma", 1257c03f739fSHeinrich Schuchardt "nochunk", "noruntime", "nosoftreserve", 1258fb1201aeSArd Biesheuvel "novamap", "no_disable_early_pci_dma" } 1259c03f739fSHeinrich Schuchardt debug: enable misc debug output. 1260c03f739fSHeinrich Schuchardt disable_early_pci_dma: disable the busmaster bit on all 1261c03f739fSHeinrich Schuchardt PCI bridges while in the EFI boot stub. 1262e52347bdSJani Nikula nochunk: disable reading files in "chunks" in the EFI 1263e52347bdSJani Nikula boot stub, as chunking can cause problems with some 1264e52347bdSJani Nikula firmware implementations. 1265e52347bdSJani Nikula noruntime : disable EFI runtime services support 1266b617c526SDan Williams nosoftreserve: The EFI_MEMORY_SP (Specific Purpose) 1267b617c526SDan Williams attribute may cause the kernel to reserve the 1268b617c526SDan Williams memory range for a memory mapping driver to 1269b617c526SDan Williams claim. Specify efi=nosoftreserve to disable this 1270b617c526SDan Williams reservation and treat the memory by its base type 1271b617c526SDan Williams (i.e. EFI_CONVENTIONAL_MEMORY / "System RAM"). 1272c03f739fSHeinrich Schuchardt novamap: do not call SetVirtualAddressMap(). 12734444f854SMatthew Garrett no_disable_early_pci_dma: Leave the busmaster bit set 12744444f854SMatthew Garrett on all PCI bridges while in the EFI boot stub 1275e52347bdSJani Nikula 1276e52347bdSJani Nikula efi_no_storage_paranoia [EFI; X86] 1277e52347bdSJani Nikula Using this parameter you can use more than 50% of 1278e52347bdSJani Nikula your efi variable storage. Use this parameter only if 1279e52347bdSJani Nikula you are really sure that your UEFI does sane gc and 1280e52347bdSJani Nikula fulfills the spec otherwise your board may brick. 1281e52347bdSJani Nikula 1282e52347bdSJani Nikula efi_fake_mem= nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86] 1283e52347bdSJani Nikula Add arbitrary attribute to specific memory range by 1284e52347bdSJani Nikula updating original EFI memory map. 1285e52347bdSJani Nikula Region of memory which aa attribute is added to is 1286e52347bdSJani Nikula from ss to ss+nn. 1287199c8471SDan Williams 1288e52347bdSJani Nikula If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000 1289e52347bdSJani Nikula is specified, EFI_MEMORY_MORE_RELIABLE(0x10000) 1290e52347bdSJani Nikula attribute is added to range 0x100000000-0x180000000 and 1291e52347bdSJani Nikula 0x10a0000000-0x1120000000. 1292e52347bdSJani Nikula 1293199c8471SDan Williams If efi_fake_mem=8G@9G:0x40000 is specified, the 1294199c8471SDan Williams EFI_MEMORY_SP(0x40000) attribute is added to 1295199c8471SDan Williams range 0x240000000-0x43fffffff. 1296199c8471SDan Williams 1297e52347bdSJani Nikula Using this parameter you can do debugging of EFI memmap 1298199c8471SDan Williams related features. For example, you can do debugging of 1299e52347bdSJani Nikula Address Range Mirroring feature even if your box 1300199c8471SDan Williams doesn't support it, or mark specific memory as 1301199c8471SDan Williams "soft reserved". 1302e52347bdSJani Nikula 1303e52347bdSJani Nikula efivar_ssdt= [EFI; X86] Name of an EFI variable that contains an SSDT 1304e52347bdSJani Nikula that is to be dynamically loaded by Linux. If there are 1305e52347bdSJani Nikula multiple variables with the same name but with different 1306e52347bdSJani Nikula vendor GUIDs, all of them will be loaded. See 1307cb1aaebeSMauro Carvalho Chehab Documentation/admin-guide/acpi/ssdt-overlays.rst for details. 1308e52347bdSJani Nikula 1309e52347bdSJani Nikula 1310e52347bdSJani Nikula eisa_irq_edge= [PARISC,HW] 1311e52347bdSJani Nikula See header of drivers/parisc/eisa.c. 1312e52347bdSJani Nikula 1313e52347bdSJani Nikula elanfreq= [X86-32] 1314e52347bdSJani Nikula See comment before function elanfreq_setup() in 1315e52347bdSJani Nikula arch/x86/kernel/cpu/cpufreq/elanfreq.c. 1316e52347bdSJani Nikula 1317e52347bdSJani Nikula elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390] 1318e52347bdSJani Nikula Specifies physical address of start of kernel core 1319e52347bdSJani Nikula image elf header and optionally the size. Generally 1320e52347bdSJani Nikula kexec loader will pass this option to capture kernel. 1321330d4810SMauro Carvalho Chehab See Documentation/admin-guide/kdump/kdump.rst for details. 1322e52347bdSJani Nikula 1323e52347bdSJani Nikula enable_mtrr_cleanup [X86] 1324e52347bdSJani Nikula The kernel tries to adjust MTRR layout from continuous 1325e52347bdSJani Nikula to discrete, to make X server driver able to add WB 1326e52347bdSJani Nikula entry later. This parameter enables that. 1327e52347bdSJani Nikula 1328e52347bdSJani Nikula enable_timer_pin_1 [X86] 1329e52347bdSJani Nikula Enable PIN 1 of APIC timer 1330e52347bdSJani Nikula Can be useful to work around chipset bugs 1331e52347bdSJani Nikula (in particular on some ATI chipsets). 1332e52347bdSJani Nikula The kernel tries to set a reasonable default. 1333e52347bdSJani Nikula 1334e52347bdSJani Nikula enforcing [SELINUX] Set initial enforcing status. 1335e52347bdSJani Nikula Format: {"0" | "1"} 1336e52347bdSJani Nikula See security/selinux/Kconfig help text. 1337e52347bdSJani Nikula 0 -- permissive (log only, no denials). 1338e52347bdSJani Nikula 1 -- enforcing (deny and log). 1339e52347bdSJani Nikula Default value is 0. 1340d41415ebSStephen Smalley Value can be changed at runtime via 1341d41415ebSStephen Smalley /sys/fs/selinux/enforce. 1342e52347bdSJani Nikula 1343e52347bdSJani Nikula erst_disable [ACPI] 1344e52347bdSJani Nikula Disable Error Record Serialization Table (ERST) 1345e52347bdSJani Nikula support. 1346e52347bdSJani Nikula 1347e52347bdSJani Nikula ether= [HW,NET] Ethernet cards parameters 1348e52347bdSJani Nikula This option is obsoleted by the "netdev=" option, which 1349e52347bdSJani Nikula has equivalent usage. See its documentation for details. 1350e52347bdSJani Nikula 1351e52347bdSJani Nikula evm= [EVM] 1352e52347bdSJani Nikula Format: { "fix" } 1353e52347bdSJani Nikula Permit 'security.evm' to be updated regardless of 1354e52347bdSJani Nikula current integrity status. 1355e52347bdSJani Nikula 1356e52347bdSJani Nikula failslab= 13572c739cedSAlbert van der Linde fail_usercopy= 1358e52347bdSJani Nikula fail_page_alloc= 1359e52347bdSJani Nikula fail_make_request=[KNL] 1360e52347bdSJani Nikula General fault injection mechanism. 1361e52347bdSJani Nikula Format: <interval>,<probability>,<space>,<times> 1362e52347bdSJani Nikula See also Documentation/fault-injection/. 1363e52347bdSJani Nikula 1364316cdaa1SMahesh Bandewar fb_tunnels= [NET] 1365316cdaa1SMahesh Bandewar Format: { initns | none } 1366316cdaa1SMahesh Bandewar See Documentation/admin-guide/sysctl/net.rst for 1367316cdaa1SMahesh Bandewar fb_tunnels_only_for_init_ns 1368316cdaa1SMahesh Bandewar 1369e52347bdSJani Nikula floppy= [HW] 1370e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/floppy.rst. 1371e52347bdSJani Nikula 1372e52347bdSJani Nikula force_pal_cache_flush 1373e52347bdSJani Nikula [IA-64] Avoid check_sal_cache_flush which may hang on 1374e52347bdSJani Nikula buggy SAL_CACHE_FLUSH implementations. Using this 1375e52347bdSJani Nikula parameter will force ia64_sal_cache_flush to call 1376e52347bdSJani Nikula ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. 1377e52347bdSJani Nikula 1378e52347bdSJani Nikula forcepae [X86-32] 1379e52347bdSJani Nikula Forcefully enable Physical Address Extension (PAE). 1380e52347bdSJani Nikula Many Pentium M systems disable PAE but may have a 1381e52347bdSJani Nikula functionally usable PAE implementation. 1382e52347bdSJani Nikula Warning: use of this parameter will taint the kernel 1383e52347bdSJani Nikula and may cause unknown problems. 1384e52347bdSJani Nikula 1385e52347bdSJani Nikula ftrace=[tracer] 1386e52347bdSJani Nikula [FTRACE] will set and start the specified tracer 1387e52347bdSJani Nikula as early as possible in order to facilitate early 1388e52347bdSJani Nikula boot debugging. 1389e52347bdSJani Nikula 1390e52347bdSJani Nikula ftrace_dump_on_oops[=orig_cpu] 1391e52347bdSJani Nikula [FTRACE] will dump the trace buffers on oops. 1392e52347bdSJani Nikula If no parameter is passed, ftrace will dump 1393e52347bdSJani Nikula buffers of all CPUs, but if you pass orig_cpu, it will 1394e52347bdSJani Nikula dump only the buffer of the CPU that triggered the 1395e52347bdSJani Nikula oops. 1396e52347bdSJani Nikula 1397e52347bdSJani Nikula ftrace_filter=[function-list] 1398e52347bdSJani Nikula [FTRACE] Limit the functions traced by the function 139925942e5eSRandy Dunlap tracer at boot up. function-list is a comma-separated 1400e52347bdSJani Nikula list of functions. This list can be changed at run 1401e52347bdSJani Nikula time by the set_ftrace_filter file in the debugfs 1402e52347bdSJani Nikula tracing directory. 1403e52347bdSJani Nikula 1404e52347bdSJani Nikula ftrace_notrace=[function-list] 1405e52347bdSJani Nikula [FTRACE] Do not trace the functions specified in 1406e52347bdSJani Nikula function-list. This list can be changed at run time 1407e52347bdSJani Nikula by the set_ftrace_notrace file in the debugfs 1408e52347bdSJani Nikula tracing directory. 1409e52347bdSJani Nikula 1410e52347bdSJani Nikula ftrace_graph_filter=[function-list] 1411e52347bdSJani Nikula [FTRACE] Limit the top level callers functions traced 1412e52347bdSJani Nikula by the function graph tracer at boot up. 141325942e5eSRandy Dunlap function-list is a comma-separated list of functions 1414e52347bdSJani Nikula that can be changed at run time by the 1415e52347bdSJani Nikula set_graph_function file in the debugfs tracing directory. 1416e52347bdSJani Nikula 1417e52347bdSJani Nikula ftrace_graph_notrace=[function-list] 1418e52347bdSJani Nikula [FTRACE] Do not trace from the functions specified in 141925942e5eSRandy Dunlap function-list. This list is a comma-separated list of 1420e52347bdSJani Nikula functions that can be changed at run time by the 1421e52347bdSJani Nikula set_graph_notrace file in the debugfs tracing directory. 1422e52347bdSJani Nikula 142365a50c65STodd Brandt ftrace_graph_max_depth=<uint> 142465a50c65STodd Brandt [FTRACE] Used with the function graph tracer. This is 142565a50c65STodd Brandt the max depth it will trace into a function. This value 142665a50c65STodd Brandt can be changed at run time by the max_graph_depth file 142765a50c65STodd Brandt in the tracefs tracing directory. default: 0 (no limit) 142865a50c65STodd Brandt 14298375e74fSSaravana Kannan fw_devlink= [KNL] Create device links between consumer and supplier 14308375e74fSSaravana Kannan devices by scanning the firmware to infer the 14318375e74fSSaravana Kannan consumer/supplier relationships. This feature is 14328375e74fSSaravana Kannan especially useful when drivers are loaded as modules as 14338375e74fSSaravana Kannan it ensures proper ordering of tasks like device probing 14348375e74fSSaravana Kannan (suppliers first, then consumers), supplier boot state 14358375e74fSSaravana Kannan clean up (only after all consumers have probed), 14368375e74fSSaravana Kannan suspend/resume & runtime PM (consumers first, then 14378375e74fSSaravana Kannan suppliers). 14388375e74fSSaravana Kannan Format: { off | permissive | on | rpm } 14398375e74fSSaravana Kannan off -- Don't create device links from firmware info. 14408375e74fSSaravana Kannan permissive -- Create device links from firmware info 14418375e74fSSaravana Kannan but use it only for ordering boot state clean 14428375e74fSSaravana Kannan up (sync_state() calls). 14438375e74fSSaravana Kannan on -- Create device links from firmware info and use it 14448375e74fSSaravana Kannan to enforce probe and suspend/resume ordering. 14458375e74fSSaravana Kannan rpm -- Like "on", but also use to order runtime PM. 14468375e74fSSaravana Kannan 144719d0f5f6SSaravana Kannan fw_devlink.strict=<bool> 144819d0f5f6SSaravana Kannan [KNL] Treat all inferred dependencies as mandatory 144919d0f5f6SSaravana Kannan dependencies. This only applies for fw_devlink=on|rpm. 145019d0f5f6SSaravana Kannan Format: <bool> 145119d0f5f6SSaravana Kannan 1452e52347bdSJani Nikula gamecon.map[2|3]= 1453e52347bdSJani Nikula [HW,JOY] Multisystem joystick and NES/SNES/PSX pad 1454e52347bdSJani Nikula support via parallel port (up to 5 devices per port) 1455e52347bdSJani Nikula Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> 14561752118dSTom Saeger See also Documentation/input/devices/joystick-parport.rst 1457e52347bdSJani Nikula 1458e52347bdSJani Nikula gamma= [HW,DRM] 1459e52347bdSJani Nikula 1460be3a5b0eSRandy Dunlap gart_fix_e820= [X86-64] disable the fix e820 for K8 GART 1461e52347bdSJani Nikula Format: off | on 1462e52347bdSJani Nikula default: on 1463e52347bdSJani Nikula 1464e52347bdSJani Nikula gcov_persist= [GCOV] When non-zero (default), profiling data for 1465e52347bdSJani Nikula kernel modules is saved and remains accessible via 1466e52347bdSJani Nikula debugfs, even when the module is unloaded/reloaded. 1467e52347bdSJani Nikula When zero, profiling data is discarded and associated 1468e52347bdSJani Nikula debugfs files are removed at module unload time. 1469e52347bdSJani Nikula 147047512cfdSThomas Gleixner goldfish [X86] Enable the goldfish android emulator platform. 147147512cfdSThomas Gleixner Don't use this when you are not running on the 147247512cfdSThomas Gleixner android emulator 147347512cfdSThomas Gleixner 1474e52347bdSJani Nikula gpt [EFI] Forces disk with valid GPT signature but 1475e52347bdSJani Nikula invalid Protective MBR to be treated as GPT. If the 1476e52347bdSJani Nikula primary GPT is corrupted, it enables the backup/alternate 1477e52347bdSJani Nikula GPT to be used instead. 1478e52347bdSJani Nikula 1479e52347bdSJani Nikula grcan.enable0= [HW] Configuration of physical interface 0. Determines 1480e52347bdSJani Nikula the "Enable 0" bit of the configuration register. 1481e52347bdSJani Nikula Format: 0 | 1 1482e52347bdSJani Nikula Default: 0 1483e52347bdSJani Nikula grcan.enable1= [HW] Configuration of physical interface 1. Determines 1484e52347bdSJani Nikula the "Enable 0" bit of the configuration register. 1485e52347bdSJani Nikula Format: 0 | 1 1486e52347bdSJani Nikula Default: 0 1487e52347bdSJani Nikula grcan.select= [HW] Select which physical interface to use. 1488e52347bdSJani Nikula Format: 0 | 1 1489e52347bdSJani Nikula Default: 0 1490e52347bdSJani Nikula grcan.txsize= [HW] Sets the size of the tx buffer. 1491e52347bdSJani Nikula Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0. 1492e52347bdSJani Nikula Default: 1024 1493e52347bdSJani Nikula grcan.rxsize= [HW] Sets the size of the rx buffer. 1494e52347bdSJani Nikula Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. 1495e52347bdSJani Nikula Default: 1024 1496e52347bdSJani Nikula 1497e52347bdSJani Nikula gpio-mockup.gpio_mockup_ranges 1498e52347bdSJani Nikula [HW] Sets the ranges of gpiochip of for this device. 1499e52347bdSJani Nikula Format: <start1>,<end1>,<start2>,<end2>... 1500e52347bdSJani Nikula 1501e52347bdSJani Nikula hardlockup_all_cpu_backtrace= 1502e52347bdSJani Nikula [KNL] Should the hard-lockup detector generate 1503e52347bdSJani Nikula backtraces on all cpus. 1504f117955aSGuilherme G. Piccoli Format: 0 | 1 1505e52347bdSJani Nikula 1506e52347bdSJani Nikula hashdist= [KNL,NUMA] Large hashes allocated during boot 1507e52347bdSJani Nikula are distributed across NUMA nodes. Defaults on 1508e52347bdSJani Nikula for 64-bit NUMA, off otherwise. 1509e52347bdSJani Nikula Format: 0 | 1 (for off | on) 1510e52347bdSJani Nikula 1511e52347bdSJani Nikula hcl= [IA-64] SGI's Hardware Graph compatibility layer 1512e52347bdSJani Nikula 1513e52347bdSJani Nikula hd= [EIDE] (E)IDE hard drive subsystem geometry 1514e52347bdSJani Nikula Format: <cyl>,<head>,<sect> 1515e52347bdSJani Nikula 1516e52347bdSJani Nikula hest_disable [ACPI] 1517e52347bdSJani Nikula Disable Hardware Error Source Table (HEST) support; 1518e52347bdSJani Nikula corresponding firmware-first mode error processing 1519e52347bdSJani Nikula logic will be disabled. 1520e52347bdSJani Nikula 1521e52347bdSJani Nikula highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact 1522e52347bdSJani Nikula size of <nn>. This works even on boxes that have no 1523e52347bdSJani Nikula highmem otherwise. This also works to reduce highmem 1524e52347bdSJani Nikula size on bigger boxes. 1525e52347bdSJani Nikula 1526e52347bdSJani Nikula highres= [KNL] Enable/disable high resolution timer mode. 1527e52347bdSJani Nikula Valid parameters: "on", "off" 1528e52347bdSJani Nikula Default: "on" 1529e52347bdSJani Nikula 1530e52347bdSJani Nikula hlt [BUGS=ARM,SH] 1531e52347bdSJani Nikula 1532e52347bdSJani Nikula hpet= [X86-32,HPET] option to control HPET usage 1533e52347bdSJani Nikula Format: { enable (default) | disable | force | 1534e52347bdSJani Nikula verbose } 1535e52347bdSJani Nikula disable: disable HPET and use PIT instead 1536e52347bdSJani Nikula force: allow force enabled of undocumented chips (ICH4, 1537e52347bdSJani Nikula VIA, nVidia) 1538e52347bdSJani Nikula verbose: show contents of HPET registers during setup 1539e52347bdSJani Nikula 1540e52347bdSJani Nikula hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET 1541e52347bdSJani Nikula registers. Default set by CONFIG_HPET_MMAP_DEFAULT. 1542e52347bdSJani Nikula 1543bc47190dSRandy Dunlap hugetlb_cma= [HW,CMA] The size of a CMA area used for allocation 1544cf11e85fSRoman Gushchin of gigantic hugepages. 1545cf11e85fSRoman Gushchin Format: nn[KMGTPE] 1546cf11e85fSRoman Gushchin 1547bc47190dSRandy Dunlap Reserve a CMA area of given size and allocate gigantic 1548bc47190dSRandy Dunlap hugepages using the CMA allocator. If enabled, the 1549cf11e85fSRoman Gushchin boot-time allocation of gigantic hugepages is skipped. 1550cf11e85fSRoman Gushchin 1551282f4214SMike Kravetz hugepages= [HW] Number of HugeTLB pages to allocate at boot. 1552282f4214SMike Kravetz If this follows hugepagesz (below), it specifies 1553282f4214SMike Kravetz the number of pages of hugepagesz to be allocated. 1554282f4214SMike Kravetz If this is the first HugeTLB parameter on the command 1555282f4214SMike Kravetz line, it specifies the number of pages to allocate for 1556282f4214SMike Kravetz the default huge page size. See also 1557282f4214SMike Kravetz Documentation/admin-guide/mm/hugetlbpage.rst. 1558282f4214SMike Kravetz Format: <integer> 1559282f4214SMike Kravetz 1560282f4214SMike Kravetz hugepagesz= 1561282f4214SMike Kravetz [HW] The size of the HugeTLB pages. This is used in 1562282f4214SMike Kravetz conjunction with hugepages (above) to allocate huge 1563282f4214SMike Kravetz pages of a specific size at boot. The pair 1564282f4214SMike Kravetz hugepagesz=X hugepages=Y can be specified once for 1565282f4214SMike Kravetz each supported huge page size. Huge page sizes are 1566282f4214SMike Kravetz architecture dependent. See also 1567282f4214SMike Kravetz Documentation/admin-guide/mm/hugetlbpage.rst. 1568282f4214SMike Kravetz Format: size[KMG] 1569e52347bdSJani Nikula 1570a49d9c0aSOmar Sandoval hung_task_panic= 1571a49d9c0aSOmar Sandoval [KNL] Should the hung task detector generate panics. 1572f117955aSGuilherme G. Piccoli Format: 0 | 1 1573a49d9c0aSOmar Sandoval 1574b467f3efSVlastimil Babka A value of 1 instructs the kernel to panic when a 1575a49d9c0aSOmar Sandoval hung task is detected. The default value is controlled 1576a49d9c0aSOmar Sandoval by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time 1577a49d9c0aSOmar Sandoval option. The value selected by this boot parameter can 1578a49d9c0aSOmar Sandoval be changed later by the kernel.hung_task_panic sysctl. 1579a49d9c0aSOmar Sandoval 1580e52347bdSJani Nikula hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) 1581e52347bdSJani Nikula terminal devices. Valid values: 0..8 1582e52347bdSJani Nikula hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. 1583e52347bdSJani Nikula If specified, z/VM IUCV HVC accepts connections 1584e52347bdSJani Nikula from listed z/VM user IDs only. 15853a025de6SYi Sun 15863a025de6SYi Sun hv_nopvspin [X86,HYPER_V] Disables the paravirt spinlock optimizations 15873a025de6SYi Sun which allow the hypervisor to 'idle' the 15883a025de6SYi Sun guest on lock contention. 15893a025de6SYi Sun 1590e52347bdSJani Nikula keep_bootcon [KNL] 1591e52347bdSJani Nikula Do not unregister boot console at start. This is only 1592e52347bdSJani Nikula useful for debugging when something happens in the window 1593e52347bdSJani Nikula between unregistering the boot console and initializing 1594e52347bdSJani Nikula the real console. 1595e52347bdSJani Nikula 1596e52347bdSJani Nikula i2c_bus= [HW] Override the default board specific I2C bus speed 1597e52347bdSJani Nikula or register an additional I2C bus that is not 1598e52347bdSJani Nikula registered from board initialization code. 1599e52347bdSJani Nikula Format: 1600e52347bdSJani Nikula <bus_id>,<clkrate> 1601e52347bdSJani Nikula 1602e52347bdSJani Nikula i8042.debug [HW] Toggle i8042 debug mode 1603e52347bdSJani Nikula i8042.unmask_kbd_data 1604e52347bdSJani Nikula [HW] Enable printing of interrupt data from the KBD port 1605e52347bdSJani Nikula (disabled by default, and as a pre-condition 1606e52347bdSJani Nikula requires that i8042.debug=1 be enabled) 1607e52347bdSJani Nikula i8042.direct [HW] Put keyboard port into non-translated mode 1608e52347bdSJani Nikula i8042.dumbkbd [HW] Pretend that controller can only read data from 1609e52347bdSJani Nikula keyboard and cannot control its state 1610e52347bdSJani Nikula (Don't attempt to blink the leds) 1611e52347bdSJani Nikula i8042.noaux [HW] Don't check for auxiliary (== mouse) port 1612e52347bdSJani Nikula i8042.nokbd [HW] Don't check/create keyboard port 1613e52347bdSJani Nikula i8042.noloop [HW] Disable the AUX Loopback command while probing 1614e52347bdSJani Nikula for the AUX port 1615e52347bdSJani Nikula i8042.nomux [HW] Don't check presence of an active multiplexing 1616e52347bdSJani Nikula controller 1617e52347bdSJani Nikula i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX 1618e52347bdSJani Nikula controllers 1619e52347bdSJani Nikula i8042.notimeout [HW] Ignore timeout condition signalled by controller 1620e52347bdSJani Nikula i8042.reset [HW] Reset the controller during init, cleanup and 1621e52347bdSJani Nikula suspend-to-ram transitions, only during s2r 1622e52347bdSJani Nikula transitions, or never reset 1623e52347bdSJani Nikula Format: { 1 | Y | y | 0 | N | n } 1624e52347bdSJani Nikula 1, Y, y: always reset controller 1625e52347bdSJani Nikula 0, N, n: don't ever reset controller 1626e52347bdSJani Nikula Default: only on s2r transitions on x86; most other 1627e52347bdSJani Nikula architectures force reset to be always executed 1628e52347bdSJani Nikula i8042.unlock [HW] Unlock (ignore) the keylock 1629e52347bdSJani Nikula i8042.kbdreset [HW] Reset device connected to KBD port 1630e52347bdSJani Nikula 1631e52347bdSJani Nikula i810= [HW,DRM] 1632e52347bdSJani Nikula 1633e52347bdSJani Nikula i8k.ignore_dmi [HW] Continue probing hardware even if DMI data 1634e52347bdSJani Nikula indicates that the driver is running on unsupported 1635e52347bdSJani Nikula hardware. 1636e52347bdSJani Nikula i8k.force [HW] Activate i8k driver even if SMM BIOS signature 1637e52347bdSJani Nikula does not match list of supported models. 1638e52347bdSJani Nikula i8k.power_status 1639e52347bdSJani Nikula [HW] Report power status in /proc/i8k 1640e52347bdSJani Nikula (disabled by default) 1641e52347bdSJani Nikula i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN 1642e52347bdSJani Nikula capability is set. 1643e52347bdSJani Nikula 1644e52347bdSJani Nikula i915.invert_brightness= 1645e52347bdSJani Nikula [DRM] Invert the sense of the variable that is used to 1646e52347bdSJani Nikula set the brightness of the panel backlight. Normally a 1647e52347bdSJani Nikula brightness value of 0 indicates backlight switched off, 1648e52347bdSJani Nikula and the maximum of the brightness value sets the backlight 1649e52347bdSJani Nikula to maximum brightness. If this parameter is set to 0 1650e52347bdSJani Nikula (default) and the machine requires it, or this parameter 1651e52347bdSJani Nikula is set to 1, a brightness value of 0 sets the backlight 1652e52347bdSJani Nikula to maximum brightness, and the maximum of the brightness 1653e52347bdSJani Nikula value switches the backlight off. 1654e52347bdSJani Nikula -1 -- never invert brightness 1655e52347bdSJani Nikula 0 -- machine default 1656e52347bdSJani Nikula 1 -- force brightness inversion 1657e52347bdSJani Nikula 1658e52347bdSJani Nikula icn= [HW,ISDN] 1659e52347bdSJani Nikula Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] 1660e52347bdSJani Nikula 1661e52347bdSJani Nikula ide-core.nodma= [HW] (E)IDE subsystem 1662e52347bdSJani Nikula Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc 1663e52347bdSJani Nikula .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr 1664e52347bdSJani Nikula .cdrom .chs .ignore_cable are additional options 1665d7b461c5SMauro Carvalho Chehab See Documentation/ide/ide.rst. 1666e52347bdSJani Nikula 1667e52347bdSJani Nikula ide-generic.probe-mask= [HW] (E)IDE subsystem 1668e52347bdSJani Nikula Format: <int> 1669e52347bdSJani Nikula Probe mask for legacy ISA IDE ports. Depending on 1670e52347bdSJani Nikula platform up to 6 ports are supported, enabled by 1671e52347bdSJani Nikula setting corresponding bits in the mask to 1. The 1672e52347bdSJani Nikula default value is 0x0, which has a special meaning. 1673e52347bdSJani Nikula On systems that have PCI, it triggers scanning the 1674e52347bdSJani Nikula PCI bus for the first and the second port, which 1675e52347bdSJani Nikula are then probed. On systems without PCI the value 1676e52347bdSJani Nikula of 0x0 enables probing the two first ports as if it 1677e52347bdSJani Nikula was 0x3. 1678e52347bdSJani Nikula 1679e52347bdSJani Nikula ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem 1680e52347bdSJani Nikula Claim all unknown PCI IDE storage controllers. 1681e52347bdSJani Nikula 1682e52347bdSJani Nikula idle= [X86] 1683e52347bdSJani Nikula Format: idle=poll, idle=halt, idle=nomwait 1684e52347bdSJani Nikula Poll forces a polling idle loop that can slightly 1685e52347bdSJani Nikula improve the performance of waking up a idle CPU, but 1686e52347bdSJani Nikula will use a lot of power and make the system run hot. 1687e52347bdSJani Nikula Not recommended. 1688e52347bdSJani Nikula idle=halt: Halt is forced to be used for CPU idle. 1689e52347bdSJani Nikula In such case C2/C3 won't be used again. 1690e52347bdSJani Nikula idle=nomwait: Disable mwait for CPU C-states 1691e52347bdSJani Nikula 169203d939c7SDave Jiang idxd.sva= [HW] 169303d939c7SDave Jiang Format: <bool> 169403d939c7SDave Jiang Allow force disabling of Shared Virtual Memory (SVA) 169503d939c7SDave Jiang support for the idxd driver. By default it is set to 169603d939c7SDave Jiang true (1). 169703d939c7SDave Jiang 1698e52347bdSJani Nikula ieee754= [MIPS] Select IEEE Std 754 conformance mode 1699e52347bdSJani Nikula Format: { strict | legacy | 2008 | relaxed } 1700e52347bdSJani Nikula Default: strict 1701e52347bdSJani Nikula 1702e52347bdSJani Nikula Choose which programs will be accepted for execution 1703e52347bdSJani Nikula based on the IEEE 754 NaN encoding(s) supported by 1704e52347bdSJani Nikula the FPU and the NaN encoding requested with the value 1705e52347bdSJani Nikula of an ELF file header flag individually set by each 1706e52347bdSJani Nikula binary. Hardware implementations are permitted to 1707e52347bdSJani Nikula support either or both of the legacy and the 2008 NaN 1708e52347bdSJani Nikula encoding mode. 1709e52347bdSJani Nikula 1710e52347bdSJani Nikula Available settings are as follows: 1711e52347bdSJani Nikula strict accept binaries that request a NaN encoding 1712e52347bdSJani Nikula supported by the FPU 1713e52347bdSJani Nikula legacy only accept legacy-NaN binaries, if supported 1714e52347bdSJani Nikula by the FPU 1715e52347bdSJani Nikula 2008 only accept 2008-NaN binaries, if supported 1716e52347bdSJani Nikula by the FPU 1717e52347bdSJani Nikula relaxed accept any binaries regardless of whether 1718e52347bdSJani Nikula supported by the FPU 1719e52347bdSJani Nikula 1720e52347bdSJani Nikula The FPU emulator is always able to support both NaN 1721e52347bdSJani Nikula encodings, so if no FPU hardware is present or it has 1722e52347bdSJani Nikula been disabled with 'nofpu', then the settings of 1723e52347bdSJani Nikula 'legacy' and '2008' strap the emulator accordingly, 1724e52347bdSJani Nikula 'relaxed' straps the emulator for both legacy-NaN and 1725e52347bdSJani Nikula 2008-NaN, whereas 'strict' enables legacy-NaN only on 1726e52347bdSJani Nikula legacy processors and both NaN encodings on MIPS32 or 1727e52347bdSJani Nikula MIPS64 CPUs. 1728e52347bdSJani Nikula 1729e52347bdSJani Nikula The setting for ABS.fmt/NEG.fmt instruction execution 1730e52347bdSJani Nikula mode generally follows that for the NaN encoding, 1731e52347bdSJani Nikula except where unsupported by hardware. 1732e52347bdSJani Nikula 1733e52347bdSJani Nikula ignore_loglevel [KNL] 1734e52347bdSJani Nikula Ignore loglevel setting - this will print /all/ 1735e52347bdSJani Nikula kernel messages to the console. Useful for debugging. 1736e52347bdSJani Nikula We also add it as printk module parameter, so users 1737e52347bdSJani Nikula could change it dynamically, usually by 1738e52347bdSJani Nikula /sys/module/printk/parameters/ignore_loglevel. 1739e52347bdSJani Nikula 1740e52347bdSJani Nikula ignore_rlimit_data 1741e52347bdSJani Nikula Ignore RLIMIT_DATA setting for data mappings, 1742e52347bdSJani Nikula print warning at first misuse. Can be changed via 1743e52347bdSJani Nikula /sys/module/kernel/parameters/ignore_rlimit_data. 1744e52347bdSJani Nikula 1745e52347bdSJani Nikula ihash_entries= [KNL] 1746e52347bdSJani Nikula Set number of hash buckets for inode cache. 1747e52347bdSJani Nikula 1748e52347bdSJani Nikula ima_appraise= [IMA] appraise integrity measurements 1749e52347bdSJani Nikula Format: { "off" | "enforce" | "fix" | "log" } 1750e52347bdSJani Nikula default: "enforce" 1751e52347bdSJani Nikula 175241475a3eSPetr Vorel ima_appraise_tcb [IMA] Deprecated. Use ima_policy= instead. 1753e52347bdSJani Nikula The builtin appraise policy appraises all files 1754e52347bdSJani Nikula owned by uid=0. 1755e52347bdSJani Nikula 1756d68a6fe9SMimi Zohar ima_canonical_fmt [IMA] 1757d68a6fe9SMimi Zohar Use the canonical format for the binary runtime 1758d68a6fe9SMimi Zohar measurements, instead of host native format. 1759d68a6fe9SMimi Zohar 1760e52347bdSJani Nikula ima_hash= [IMA] 1761e52347bdSJani Nikula Format: { md5 | sha1 | rmd160 | sha256 | sha384 1762e52347bdSJani Nikula | sha512 | ... } 1763e52347bdSJani Nikula default: "sha1" 1764e52347bdSJani Nikula 1765e52347bdSJani Nikula The list of supported hash algorithms is defined 1766e52347bdSJani Nikula in crypto/hash_info.h. 1767e52347bdSJani Nikula 1768e52347bdSJani Nikula ima_policy= [IMA] 176933ce9549SMimi Zohar The builtin policies to load during IMA setup. 17709e67028eSMimi Zohar Format: "tcb | appraise_tcb | secure_boot | 177103cee168SLakshmi Ramasubramanian fail_securely | critical_data" 177233ce9549SMimi Zohar 177333ce9549SMimi Zohar The "tcb" policy measures all programs exec'd, files 177433ce9549SMimi Zohar mmap'd for exec, and all files opened with the read 177533ce9549SMimi Zohar mode bit set by either the effective uid (euid=0) or 177633ce9549SMimi Zohar uid=0. 177733ce9549SMimi Zohar 177833ce9549SMimi Zohar The "appraise_tcb" policy appraises the integrity of 177941475a3eSPetr Vorel all files owned by root. 1780e52347bdSJani Nikula 1781503ceaefSMimi Zohar The "secure_boot" policy appraises the integrity 1782503ceaefSMimi Zohar of files (eg. kexec kernel image, kernel modules, 1783503ceaefSMimi Zohar firmware, policy, etc) based on file signatures. 1784e52347bdSJani Nikula 17859e67028eSMimi Zohar The "fail_securely" policy forces file signature 17869e67028eSMimi Zohar verification failure also on privileged mounted 17879e67028eSMimi Zohar filesystems with the SB_I_UNVERIFIABLE_SIGNATURE 17889e67028eSMimi Zohar flag. 17899e67028eSMimi Zohar 179003cee168SLakshmi Ramasubramanian The "critical_data" policy measures kernel integrity 179103cee168SLakshmi Ramasubramanian critical data. 179203cee168SLakshmi Ramasubramanian 1793e52347bdSJani Nikula ima_tcb [IMA] Deprecated. Use ima_policy= instead. 1794e52347bdSJani Nikula Load a policy which meets the needs of the Trusted 1795e52347bdSJani Nikula Computing Base. This means IMA will measure all 1796e52347bdSJani Nikula programs exec'd, files mmap'd for exec, and all files 1797e52347bdSJani Nikula opened for read by uid=0. 1798e52347bdSJani Nikula 1799e52347bdSJani Nikula ima_template= [IMA] 1800e52347bdSJani Nikula Select one of defined IMA measurements template formats. 1801e52347bdSJani Nikula Formats: { "ima" | "ima-ng" | "ima-sig" } 1802e52347bdSJani Nikula Default: "ima-ng" 1803e52347bdSJani Nikula 1804e52347bdSJani Nikula ima_template_fmt= 1805e52347bdSJani Nikula [IMA] Define a custom template format. 1806e52347bdSJani Nikula Format: { "field1|...|fieldN" } 1807e52347bdSJani Nikula 1808e52347bdSJani Nikula ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage 1809e52347bdSJani Nikula Format: <min_file_size> 1810e52347bdSJani Nikula Set the minimal file size for using asynchronous hash. 1811e52347bdSJani Nikula If left unspecified, ahash usage is disabled. 1812e52347bdSJani Nikula 1813e52347bdSJani Nikula ahash performance varies for different data sizes on 1814e52347bdSJani Nikula different crypto accelerators. This option can be used 1815e52347bdSJani Nikula to achieve the best performance for a particular HW. 1816e52347bdSJani Nikula 1817e52347bdSJani Nikula ima.ahash_bufsize= [IMA] Asynchronous hash buffer size 1818e52347bdSJani Nikula Format: <bufsize> 1819e52347bdSJani Nikula Set hashing buffer size. Default: 4k. 1820e52347bdSJani Nikula 1821e52347bdSJani Nikula ahash performance varies for different chunk sizes on 1822e52347bdSJani Nikula different crypto accelerators. This option can be used 1823e52347bdSJani Nikula to achieve best performance for particular HW. 1824e52347bdSJani Nikula 1825e52347bdSJani Nikula init= [KNL] 1826e52347bdSJani Nikula Format: <full_path> 1827e52347bdSJani Nikula Run specified binary instead of /sbin/init as init 1828e52347bdSJani Nikula process. 1829e52347bdSJani Nikula 1830e52347bdSJani Nikula initcall_debug [KNL] Trace initcalls as they are executed. Useful 1831e52347bdSJani Nikula for working out where the kernel is dying during 1832e52347bdSJani Nikula startup. 1833e52347bdSJani Nikula 1834e52347bdSJani Nikula initcall_blacklist= [KNL] Do not execute a comma-separated list of 1835e52347bdSJani Nikula initcall functions. Useful for debugging built-in 1836e52347bdSJani Nikula modules and initcalls. 1837e52347bdSJani Nikula 1838e52347bdSJani Nikula initrd= [BOOT] Specify the location of the initial ramdisk 1839e52347bdSJani Nikula 1840694cfd87SRonald G. Minnich initrdmem= [KNL] Specify a physical address and size from which to 1841694cfd87SRonald G. Minnich load the initrd. If an initrd is compiled in or 1842694cfd87SRonald G. Minnich specified in the bootparams, it takes priority over this 1843694cfd87SRonald G. Minnich setting. 1844694cfd87SRonald G. Minnich Format: ss[KMG],nn[KMG] 1845694cfd87SRonald G. Minnich Default is 0, 0 1846694cfd87SRonald G. Minnich 18476471384aSAlexander Potapenko init_on_alloc= [MM] Fill newly allocated pages and heap objects with 18486471384aSAlexander Potapenko zeroes. 18496471384aSAlexander Potapenko Format: 0 | 1 18506471384aSAlexander Potapenko Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON. 18516471384aSAlexander Potapenko 18526471384aSAlexander Potapenko init_on_free= [MM] Fill freed pages and heap objects with zeroes. 18536471384aSAlexander Potapenko Format: 0 | 1 18546471384aSAlexander Potapenko Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON. 18556471384aSAlexander Potapenko 1856be3a5b0eSRandy Dunlap init_pkru= [X86] Specify the default memory protection keys rights 1857e52347bdSJani Nikula register contents for all processes. 0x55555554 by 1858e52347bdSJani Nikula default (disallow access to all but pkey 0). Can 1859e52347bdSJani Nikula override in debugfs after boot. 1860e52347bdSJani Nikula 1861e52347bdSJani Nikula inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver 1862e52347bdSJani Nikula Format: <irq> 1863e52347bdSJani Nikula 1864be3a5b0eSRandy Dunlap int_pln_enable [X86] Enable power limit notification interrupt 1865e52347bdSJani Nikula 1866e52347bdSJani Nikula integrity_audit=[IMA] 1867e52347bdSJani Nikula Format: { "0" | "1" } 1868e52347bdSJani Nikula 0 -- basic integrity auditing messages. (Default) 1869e52347bdSJani Nikula 1 -- additional integrity auditing messages. 1870e52347bdSJani Nikula 1871e52347bdSJani Nikula intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option 1872e52347bdSJani Nikula on 1873e52347bdSJani Nikula Enable intel iommu driver. 1874e52347bdSJani Nikula off 1875e52347bdSJani Nikula Disable intel iommu driver. 1876e52347bdSJani Nikula igfx_off [Default Off] 1877e52347bdSJani Nikula By default, gfx is mapped as normal device. If a gfx 1878e52347bdSJani Nikula device has a dedicated DMAR unit, the DMAR unit is 1879e52347bdSJani Nikula bypassed by not enabling DMAR with this option. In 1880e52347bdSJani Nikula this case, gfx device will use physical address for 1881e52347bdSJani Nikula DMA. 1882be3a5b0eSRandy Dunlap forcedac [X86-64] 1883e52347bdSJani Nikula With this option iommu will not optimize to look 1884e52347bdSJani Nikula for io virtual address below 32-bit forcing dual 1885e52347bdSJani Nikula address cycle on pci bus for cards supporting greater 1886e52347bdSJani Nikula than 32-bit addressing. The default is to look 1887e52347bdSJani Nikula for translation below 32-bit and if not available 1888e52347bdSJani Nikula then look in the higher range. 1889e52347bdSJani Nikula strict [Default Off] 1890e52347bdSJani Nikula With this option on every unmap_single operation will 1891e52347bdSJani Nikula result in a hardware IOTLB flush operation as opposed 1892e52347bdSJani Nikula to batching them for performance. 1893e52347bdSJani Nikula sp_off [Default Off] 1894e52347bdSJani Nikula By default, super page will be supported if Intel IOMMU 1895e52347bdSJani Nikula has the capability. With this option, super page will 1896e52347bdSJani Nikula not be supported. 18978950dcd8SLu Baolu sm_on [Default Off] 18988950dcd8SLu Baolu By default, scalable mode will be disabled even if the 1899765b6a98SLu Baolu hardware advertises that it has support for the scalable 1900765b6a98SLu Baolu mode translation. With this option set, scalable mode 19018950dcd8SLu Baolu will be used on hardware which claims to support it. 1902bfd20f1cSShaohua Li tboot_noforce [Default Off] 1903bfd20f1cSShaohua Li Do not force the Intel IOMMU enabled under tboot. 1904bfd20f1cSShaohua Li By default, tboot will force Intel IOMMU on, which 1905bfd20f1cSShaohua Li could harm performance of some high-throughput 1906bfd20f1cSShaohua Li devices like 40GBit network cards, even if identity 1907bfd20f1cSShaohua Li mapping is enabled. 1908bfd20f1cSShaohua Li Note that using this option lowers the security 1909bfd20f1cSShaohua Li provided by tboot because it makes the system 1910bfd20f1cSShaohua Li vulnerable to DMA attacks. 1911e52347bdSJani Nikula 1912e52347bdSJani Nikula intel_idle.max_cstate= [KNL,HW,ACPI,X86] 1913e52347bdSJani Nikula 0 disables intel_idle and fall back on acpi_idle. 1914e52347bdSJani Nikula 1 to 9 specify maximum depth of C-state. 1915e52347bdSJani Nikula 1916e52347bdSJani Nikula intel_pstate= [X86] 1917e52347bdSJani Nikula disable 1918e52347bdSJani Nikula Do not enable intel_pstate as the default 1919e52347bdSJani Nikula scaling driver for the supported processors 19207b9dc3f7SLinus Torvalds passive 19217b9dc3f7SLinus Torvalds Use intel_pstate as a scaling driver, but configure it 19227b9dc3f7SLinus Torvalds to work with generic cpufreq governors (instead of 19237b9dc3f7SLinus Torvalds enabling its internal governor). This mode cannot be 19247b9dc3f7SLinus Torvalds used along with the hardware-managed P-states (HWP) 19257b9dc3f7SLinus Torvalds feature. 1926e52347bdSJani Nikula force 1927e52347bdSJani Nikula Enable intel_pstate on systems that prohibit it by default 1928e52347bdSJani Nikula in favor of acpi-cpufreq. Forcing the intel_pstate driver 1929e52347bdSJani Nikula instead of acpi-cpufreq may disable platform features, such 1930e52347bdSJani Nikula as thermal controls and power capping, that rely on ACPI 1931e52347bdSJani Nikula P-States information being indicated to OSPM and therefore 1932e52347bdSJani Nikula should be used with caution. This option does not work with 1933e52347bdSJani Nikula processors that aren't supported by the intel_pstate driver 1934e52347bdSJani Nikula or on platforms that use pcc-cpufreq instead of acpi-cpufreq. 1935e52347bdSJani Nikula no_hwp 1936e52347bdSJani Nikula Do not enable hardware P state control (HWP) 1937e52347bdSJani Nikula if available. 1938e52347bdSJani Nikula hwp_only 1939e52347bdSJani Nikula Only load intel_pstate on systems which support 1940e52347bdSJani Nikula hardware P state control (HWP) if available. 1941e52347bdSJani Nikula support_acpi_ppc 1942e52347bdSJani Nikula Enforce ACPI _PPC performance limits. If the Fixed ACPI 1943e52347bdSJani Nikula Description Table, specifies preferred power management 1944e52347bdSJani Nikula profile as "Enterprise Server" or "Performance Server", 1945e52347bdSJani Nikula then this feature is turned on by default. 19467b9dc3f7SLinus Torvalds per_cpu_perf_limits 19477b9dc3f7SLinus Torvalds Allow per-logical-CPU P-State performance control limits using 19487b9dc3f7SLinus Torvalds cpufreq sysfs interface 1949e52347bdSJani Nikula 1950e52347bdSJani Nikula intremap= [X86-64, Intel-IOMMU] 1951e52347bdSJani Nikula on enable Interrupt Remapping (default) 1952e52347bdSJani Nikula off disable Interrupt Remapping 1953e52347bdSJani Nikula nosid disable Source ID checking 1954e52347bdSJani Nikula no_x2apic_optout 1955e52347bdSJani Nikula BIOS x2APIC opt-out request will be ignored 1956e52347bdSJani Nikula nopost disable Interrupt Posting 1957e52347bdSJani Nikula 1958e52347bdSJani Nikula iomem= Disable strict checking of access to MMIO memory 1959e52347bdSJani Nikula strict regions from userspace. 1960e52347bdSJani Nikula relaxed 1961e52347bdSJani Nikula 1962be3a5b0eSRandy Dunlap iommu= [X86] 1963e52347bdSJani Nikula off 1964e52347bdSJani Nikula force 1965e52347bdSJani Nikula noforce 1966e52347bdSJani Nikula biomerge 1967e52347bdSJani Nikula panic 1968e52347bdSJani Nikula nopanic 1969e52347bdSJani Nikula merge 1970e52347bdSJani Nikula nomerge 1971e52347bdSJani Nikula soft 1972be3a5b0eSRandy Dunlap pt [X86] 1973be3a5b0eSRandy Dunlap nopt [X86] 1974e52347bdSJani Nikula nobypass [PPC/POWERNV] 1975e52347bdSJani Nikula Disable IOMMU bypass, using IOMMU for PCI devices. 1976e52347bdSJani Nikula 197768a6efe8SZhen Lei iommu.strict= [ARM64] Configure TLB invalidation behaviour 197868a6efe8SZhen Lei Format: { "0" | "1" } 197968a6efe8SZhen Lei 0 - Lazy mode. 198068a6efe8SZhen Lei Request that DMA unmap operations use deferred 198168a6efe8SZhen Lei invalidation of hardware TLBs, for increased 198268a6efe8SZhen Lei throughput at the cost of reduced device isolation. 198368a6efe8SZhen Lei Will fall back to strict mode if not supported by 198468a6efe8SZhen Lei the relevant IOMMU driver. 198568a6efe8SZhen Lei 1 - Strict mode (default). 198668a6efe8SZhen Lei DMA unmap operations invalidate IOMMU hardware TLBs 198768a6efe8SZhen Lei synchronously. 198868a6efe8SZhen Lei 1989fccb4e3bSWill Deacon iommu.passthrough= 1990c8fb436bSJoerg Roedel [ARM64, X86] Configure DMA to bypass the IOMMU by default. 1991fccb4e3bSWill Deacon Format: { "0" | "1" } 1992fccb4e3bSWill Deacon 0 - Use IOMMU translation for DMA. 1993fccb4e3bSWill Deacon 1 - Bypass the IOMMU for DMA. 19949d723b4cSRobin Murphy unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH. 1995e52347bdSJani Nikula 19967c42376eSRandy Dunlap io7= [HW] IO7 for Marvel-based Alpha systems 1997e52347bdSJani Nikula See comment before marvel_specify_io7 in 1998e52347bdSJani Nikula arch/alpha/kernel/core_marvel.c. 1999e52347bdSJani Nikula 2000e52347bdSJani Nikula io_delay= [X86] I/O delay method 2001e52347bdSJani Nikula 0x80 2002e52347bdSJani Nikula Standard port 0x80 based delay 2003e52347bdSJani Nikula 0xed 2004e52347bdSJani Nikula Alternate port 0xed based delay (needed on some systems) 2005e52347bdSJani Nikula udelay 2006e52347bdSJani Nikula Simple two microseconds delay 2007e52347bdSJani Nikula none 2008e52347bdSJani Nikula No delay 2009e52347bdSJani Nikula 2010e52347bdSJani Nikula ip= [IP_PNP] 20113eb30c51SNiklas Söderlund See Documentation/admin-guide/nfs/nfsroot.rst. 2012e52347bdSJani Nikula 20135ac893b8SWaiman Long ipcmni_extend [KNL] Extend the maximum number of unique System V 20145ac893b8SWaiman Long IPC identifiers from 32,768 to 16,777,216. 20155ac893b8SWaiman Long 2016e52347bdSJani Nikula irqaffinity= [SMP] Set the default irq affinity mask 2017e52347bdSJani Nikula The argument is a cpu list, as described above. 2018e52347bdSJani Nikula 20190962289bSMarc Zyngier irqchip.gicv2_force_probe= 20200962289bSMarc Zyngier [ARM, ARM64] 20210962289bSMarc Zyngier Format: <bool> 20220962289bSMarc Zyngier Force the kernel to look for the second 4kB page 20230962289bSMarc Zyngier of a GICv2 controller even if the memory range 20240962289bSMarc Zyngier exposed by the device tree is too small. 20250962289bSMarc Zyngier 2026f736d65dSMarc Zyngier irqchip.gicv3_nolpi= 2027f736d65dSMarc Zyngier [ARM, ARM64] 2028f736d65dSMarc Zyngier Force the kernel to ignore the availability of 2029f736d65dSMarc Zyngier LPIs (and by consequence ITSs). Intended for system 2030f736d65dSMarc Zyngier that use the kernel as a bootloader, and thus want 2031f736d65dSMarc Zyngier to let secondary kernels in charge of setting up 2032f736d65dSMarc Zyngier LPIs. 2033f736d65dSMarc Zyngier 2034bc3c03ccSJulien Thierry irqchip.gicv3_pseudo_nmi= [ARM64] 2035bc3c03ccSJulien Thierry Enables support for pseudo-NMIs in the kernel. This 2036bc3c03ccSJulien Thierry requires the kernel to be built with 2037bc3c03ccSJulien Thierry CONFIG_ARM64_PSEUDO_NMI. 2038bc3c03ccSJulien Thierry 2039e52347bdSJani Nikula irqfixup [HW] 2040e52347bdSJani Nikula When an interrupt is not handled search all handlers 2041e52347bdSJani Nikula for it. Intended to get systems with badly broken 2042e52347bdSJani Nikula firmware running. 2043e52347bdSJani Nikula 2044e52347bdSJani Nikula irqpoll [HW] 2045e52347bdSJani Nikula When an interrupt is not handled search all handlers 2046e52347bdSJani Nikula for it. Also check all handlers each timer 2047e52347bdSJani Nikula interrupt. Intended to get systems with badly broken 2048e52347bdSJani Nikula firmware running. 2049e52347bdSJani Nikula 2050e52347bdSJani Nikula isapnp= [ISAPNP] 2051e52347bdSJani Nikula Format: <RDP>,<reset>,<pci_scan>,<verbosity> 2052e52347bdSJani Nikula 2053d94d1053SFrederic Weisbecker isolcpus= [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance. 2054b0d40d2bSFrederic Weisbecker [Deprecated - use cpusets instead] 2055b0d40d2bSFrederic Weisbecker Format: [flag-list,]<cpu-list> 2056e52347bdSJani Nikula 2057b0d40d2bSFrederic Weisbecker Specify one or more CPUs to isolate from disturbances 2058b0d40d2bSFrederic Weisbecker specified in the flag list (default: domain): 2059b0d40d2bSFrederic Weisbecker 2060b0d40d2bSFrederic Weisbecker nohz 2061b0d40d2bSFrederic Weisbecker Disable the tick when a single task runs. 2062083c6eeaSFrederic Weisbecker 2063083c6eeaSFrederic Weisbecker A residual 1Hz tick is offloaded to workqueues, which you 2064083c6eeaSFrederic Weisbecker need to affine to housekeeping through the global 2065083c6eeaSFrederic Weisbecker workqueue's affinity configured via the 2066083c6eeaSFrederic Weisbecker /sys/devices/virtual/workqueue/cpumask sysfs file, or 2067083c6eeaSFrederic Weisbecker by using the 'domain' flag described below. 2068083c6eeaSFrederic Weisbecker 2069083c6eeaSFrederic Weisbecker NOTE: by default the global workqueue runs on all CPUs, 2070083c6eeaSFrederic Weisbecker so to protect individual CPUs the 'cpumask' file has to 2071083c6eeaSFrederic Weisbecker be configured manually after bootup. 2072083c6eeaSFrederic Weisbecker 2073b0d40d2bSFrederic Weisbecker domain 2074b0d40d2bSFrederic Weisbecker Isolate from the general SMP balancing and scheduling 2075b0d40d2bSFrederic Weisbecker algorithms. Note that performing domain isolation this way 2076b0d40d2bSFrederic Weisbecker is irreversible: it's not possible to bring back a CPU to 2077b0d40d2bSFrederic Weisbecker the domains once isolated through isolcpus. It's strongly 2078b0d40d2bSFrederic Weisbecker advised to use cpusets instead to disable scheduler load 2079b0d40d2bSFrederic Weisbecker balancing through the "cpuset.sched_load_balance" file. 2080b0d40d2bSFrederic Weisbecker It offers a much more flexible interface where CPUs can 2081b0d40d2bSFrederic Weisbecker move in and out of an isolated set anytime. 2082b0d40d2bSFrederic Weisbecker 2083b0d40d2bSFrederic Weisbecker You can move a process onto or off an "isolated" CPU via 2084b0d40d2bSFrederic Weisbecker the CPU affinity syscalls or cpuset. 2085e52347bdSJani Nikula <cpu number> begins at 0 and the maximum value is 2086e52347bdSJani Nikula "number of CPUs in system - 1". 2087e52347bdSJani Nikula 208811ea68f5SMing Lei managed_irq 208911ea68f5SMing Lei 209011ea68f5SMing Lei Isolate from being targeted by managed interrupts 209111ea68f5SMing Lei which have an interrupt mask containing isolated 209211ea68f5SMing Lei CPUs. The affinity of managed interrupts is 209311ea68f5SMing Lei handled by the kernel and cannot be changed via 209411ea68f5SMing Lei the /proc/irq/* interfaces. 209511ea68f5SMing Lei 209611ea68f5SMing Lei This isolation is best effort and only effective 209711ea68f5SMing Lei if the automatically assigned interrupt mask of a 209811ea68f5SMing Lei device queue contains isolated and housekeeping 209911ea68f5SMing Lei CPUs. If housekeeping CPUs are online then such 210011ea68f5SMing Lei interrupts are directed to the housekeeping CPU 210111ea68f5SMing Lei so that IO submitted on the housekeeping CPU 210211ea68f5SMing Lei cannot disturb the isolated CPU. 210311ea68f5SMing Lei 210411ea68f5SMing Lei If a queue's affinity mask contains only isolated 210511ea68f5SMing Lei CPUs then this parameter has no effect on the 210611ea68f5SMing Lei interrupt routing decision, though interrupts are 210711ea68f5SMing Lei only delivered when tasks running on those 210811ea68f5SMing Lei isolated CPUs submit IO. IO submitted on 210911ea68f5SMing Lei housekeeping CPUs has no influence on those 211011ea68f5SMing Lei queues. 211111ea68f5SMing Lei 2112b0d40d2bSFrederic Weisbecker The format of <cpu-list> is described above. 2113b0d40d2bSFrederic Weisbecker 2114e52347bdSJani Nikula iucv= [HW,NET] 2115e52347bdSJani Nikula 2116be3a5b0eSRandy Dunlap ivrs_ioapic [HW,X86-64] 2117e52347bdSJani Nikula Provide an override to the IOAPIC-ID<->DEVICE-ID 2118e52347bdSJani Nikula mapping provided in the IVRS ACPI table. For 2119e52347bdSJani Nikula example, to map IOAPIC-ID decimal 10 to 2120e52347bdSJani Nikula PCI device 00:14.0 write the parameter as: 2121e52347bdSJani Nikula ivrs_ioapic[10]=00:14.0 2122e52347bdSJani Nikula 2123be3a5b0eSRandy Dunlap ivrs_hpet [HW,X86-64] 2124e52347bdSJani Nikula Provide an override to the HPET-ID<->DEVICE-ID 2125e52347bdSJani Nikula mapping provided in the IVRS ACPI table. For 2126e52347bdSJani Nikula example, to map HPET-ID decimal 0 to 2127e52347bdSJani Nikula PCI device 00:14.0 write the parameter as: 2128e52347bdSJani Nikula ivrs_hpet[0]=00:14.0 2129e52347bdSJani Nikula 2130be3a5b0eSRandy Dunlap ivrs_acpihid [HW,X86-64] 2131e52347bdSJani Nikula Provide an override to the ACPI-HID:UID<->DEVICE-ID 2132e52347bdSJani Nikula mapping provided in the IVRS ACPI table. For 2133e52347bdSJani Nikula example, to map UART-HID:UID AMD0020:0 to 2134e52347bdSJani Nikula PCI device 00:14.5 write the parameter as: 2135e52347bdSJani Nikula ivrs_acpihid[00:14.5]=AMD0020:0 2136e52347bdSJani Nikula 2137e52347bdSJani Nikula js= [HW,JOY] Analog joystick 21381752118dSTom Saeger See Documentation/input/joydev/joystick.rst. 2139e52347bdSJani Nikula 2140e52347bdSJani Nikula nokaslr [KNL] 2141e52347bdSJani Nikula When CONFIG_RANDOMIZE_BASE is set, this disables 2142e52347bdSJani Nikula kernel and module base offset ASLR (Address Space 2143e52347bdSJani Nikula Layout Randomization). 2144e52347bdSJani Nikula 2145b0845ce5SMark Rutland kasan_multi_shot 2146b0845ce5SMark Rutland [KNL] Enforce KASAN (Kernel Address Sanitizer) to print 2147b0845ce5SMark Rutland report on every invalid memory access. Without this 2148b0845ce5SMark Rutland parameter KASAN will print report only for the first 2149b0845ce5SMark Rutland invalid access. 2150b0845ce5SMark Rutland 2151e52347bdSJani Nikula keepinitrd [HW,ARM] 2152e52347bdSJani Nikula 2153e52347bdSJani Nikula kernelcore= [KNL,X86,IA-64,PPC] 2154a5c6d650SDavid Rientjes Format: nn[KMGTPE] | nn% | "mirror" 2155a5c6d650SDavid Rientjes This parameter specifies the amount of memory usable by 2156a5c6d650SDavid Rientjes the kernel for non-movable allocations. The requested 2157a5c6d650SDavid Rientjes amount is spread evenly throughout all nodes in the 2158a5c6d650SDavid Rientjes system as ZONE_NORMAL. The remaining memory is used for 2159a5c6d650SDavid Rientjes movable memory in its own zone, ZONE_MOVABLE. In the 2160a5c6d650SDavid Rientjes event, a node is too small to have both ZONE_NORMAL and 2161a5c6d650SDavid Rientjes ZONE_MOVABLE, kernelcore memory will take priority and 2162a5c6d650SDavid Rientjes other nodes will have a larger ZONE_MOVABLE. 2163a5c6d650SDavid Rientjes 2164a5c6d650SDavid Rientjes ZONE_MOVABLE is used for the allocation of pages that 2165a5c6d650SDavid Rientjes may be reclaimed or moved by the page migration 2166a5c6d650SDavid Rientjes subsystem. Note that allocations like PTEs-from-HighMem 2167a5c6d650SDavid Rientjes still use the HighMem zone if it exists, and the Normal 2168e52347bdSJani Nikula zone if it does not. 2169e52347bdSJani Nikula 2170a5c6d650SDavid Rientjes It is possible to specify the exact amount of memory in 2171a5c6d650SDavid Rientjes the form of "nn[KMGTPE]", a percentage of total system 2172a5c6d650SDavid Rientjes memory in the form of "nn%", or "mirror". If "mirror" 2173e52347bdSJani Nikula option is specified, mirrored (reliable) memory is used 2174e52347bdSJani Nikula for non-movable allocations and remaining memory is used 2175a5c6d650SDavid Rientjes for Movable pages. "nn[KMGTPE]", "nn%", and "mirror" 2176a5c6d650SDavid Rientjes are exclusive, so you cannot specify multiple forms. 2177e52347bdSJani Nikula 2178e52347bdSJani Nikula kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. 2179e52347bdSJani Nikula Format: <Controller#>[,poll interval] 2180e52347bdSJani Nikula The controller # is the number of the ehci usb debug 2181e52347bdSJani Nikula port as it is probed via PCI. The poll interval is 2182e52347bdSJani Nikula optional and is the number seconds in between 2183e52347bdSJani Nikula each poll cycle to the debug port in case you need 2184e52347bdSJani Nikula the functionality for interrupting the kernel with 2185e52347bdSJani Nikula gdb or control-c on the dbgp connection. When 2186e52347bdSJani Nikula not using this parameter you use sysrq-g to break into 2187e52347bdSJani Nikula the kernel debugger. 2188e52347bdSJani Nikula 2189e52347bdSJani Nikula kgdboc= [KGDB,HW] kgdb over consoles. 2190e52347bdSJani Nikula Requires a tty driver that supports console polling, 2191e52347bdSJani Nikula or a supported polling keyboard driver (non-usb). 2192e52347bdSJani Nikula Serial only format: <serial_device>[,baud] 2193e52347bdSJani Nikula keyboard only format: kbd 2194e52347bdSJani Nikula keyboard and serial format: kbd,<serial_device>[,baud] 2195e52347bdSJani Nikula Optional Kernel mode setting: 2196e52347bdSJani Nikula kms, kbd format: kms,kbd 2197e52347bdSJani Nikula kms, kbd and serial format: kms,kbd,<ser_dev>[,baud] 2198e52347bdSJani Nikula 2199f71fc3bcSDouglas Anderson kgdboc_earlycon= [KGDB,HW] 2200f71fc3bcSDouglas Anderson If the boot console provides the ability to read 2201f71fc3bcSDouglas Anderson characters and can work in polling mode, you can use 2202f71fc3bcSDouglas Anderson this parameter to tell kgdb to use it as a backend 2203f71fc3bcSDouglas Anderson until the normal console is registered. Intended to 2204f71fc3bcSDouglas Anderson be used together with the kgdboc parameter which 2205f71fc3bcSDouglas Anderson specifies the normal console to transition to. 2206f71fc3bcSDouglas Anderson 2207f71fc3bcSDouglas Anderson The name of the early console should be specified 2208f71fc3bcSDouglas Anderson as the value of this parameter. Note that the name of 2209f71fc3bcSDouglas Anderson the early console might be different than the tty 2210f71fc3bcSDouglas Anderson name passed to kgdboc. It's OK to leave the value 2211f71fc3bcSDouglas Anderson blank and the first boot console that implements 2212f71fc3bcSDouglas Anderson read() will be picked. 2213f71fc3bcSDouglas Anderson 2214e52347bdSJani Nikula kgdbwait [KGDB] Stop kernel execution and enter the 2215e52347bdSJani Nikula kernel debugger at the earliest opportunity. 2216e52347bdSJani Nikula 2217497de97eSRandy Dunlap kmac= [MIPS] Korina ethernet MAC address. 2218e52347bdSJani Nikula Configure the RouterBoard 532 series on-chip 2219e52347bdSJani Nikula Ethernet adapter MAC address. 2220e52347bdSJani Nikula 2221e52347bdSJani Nikula kmemleak= [KNL] Boot-time kmemleak enable/disable 2222e52347bdSJani Nikula Valid arguments: on, off 2223e52347bdSJani Nikula Default: on 2224e52347bdSJani Nikula Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, 2225e52347bdSJani Nikula the default is off. 2226e52347bdSJani Nikula 2227970988e1SMasami Hiramatsu kprobe_event=[probe-list] 2228970988e1SMasami Hiramatsu [FTRACE] Add kprobe events and enable at boot time. 2229970988e1SMasami Hiramatsu The probe-list is a semicolon delimited list of probe 2230970988e1SMasami Hiramatsu definitions. Each definition is same as kprobe_events 2231970988e1SMasami Hiramatsu interface, but the parameters are comma delimited. 2232970988e1SMasami Hiramatsu For example, to add a kprobe event on vfs_read with 2233970988e1SMasami Hiramatsu arg1 and arg2, add to the command line; 2234970988e1SMasami Hiramatsu 2235970988e1SMasami Hiramatsu kprobe_event=p,vfs_read,$arg1,$arg2 2236970988e1SMasami Hiramatsu 2237970988e1SMasami Hiramatsu See also Documentation/trace/kprobetrace.rst "Kernel 2238970988e1SMasami Hiramatsu Boot Parameter" section. 2239970988e1SMasami Hiramatsu 2240de190555SJeremy Linton kpti= [ARM64] Control page table isolation of user 2241de190555SJeremy Linton and kernel address spaces. 2242de190555SJeremy Linton Default: enabled on cores which need mitigation. 2243de190555SJeremy Linton 0: force disabled 2244de190555SJeremy Linton 1: force enabled 2245de190555SJeremy Linton 2246e52347bdSJani Nikula kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. 2247e52347bdSJani Nikula Default is 0 (don't ignore, but inject #GP) 2248e52347bdSJani Nikula 2249c4ae60e4SLiran Alon kvm.enable_vmware_backdoor=[KVM] Support VMware backdoor PV interface. 2250c4ae60e4SLiran Alon Default is false (don't support). 2251c4ae60e4SLiran Alon 2252e52347bdSJani Nikula kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit 2253e52347bdSJani Nikula KVM MMU at runtime. 2254e52347bdSJani Nikula Default is 0 (off) 2255e52347bdSJani Nikula 2256b8e8c830SPaolo Bonzini kvm.nx_huge_pages= 2257b8e8c830SPaolo Bonzini [KVM] Controls the software workaround for the 2258b8e8c830SPaolo Bonzini X86_BUG_ITLB_MULTIHIT bug. 2259b8e8c830SPaolo Bonzini force : Always deploy workaround. 2260b8e8c830SPaolo Bonzini off : Never deploy workaround. 2261b8e8c830SPaolo Bonzini auto : Deploy workaround based on the presence of 2262b8e8c830SPaolo Bonzini X86_BUG_ITLB_MULTIHIT. 2263b8e8c830SPaolo Bonzini 2264b8e8c830SPaolo Bonzini Default is 'auto'. 2265b8e8c830SPaolo Bonzini 2266b8e8c830SPaolo Bonzini If the software workaround is enabled for the host, 2267b8e8c830SPaolo Bonzini guests do need not to enable it for nested guests. 2268b8e8c830SPaolo Bonzini 22691aa9b957SJunaid Shahid kvm.nx_huge_pages_recovery_ratio= 22701aa9b957SJunaid Shahid [KVM] Controls how many 4KiB pages are periodically zapped 22711aa9b957SJunaid Shahid back to huge pages. 0 disables the recovery, otherwise if 22721aa9b957SJunaid Shahid the value is N KVM will zap 1/Nth of the 4KiB pages every 22731aa9b957SJunaid Shahid minute. The default is 60. 22741aa9b957SJunaid Shahid 2275e52347bdSJani Nikula kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM. 2276e52347bdSJani Nikula Default is 1 (enabled) 2277e52347bdSJani Nikula 2278e52347bdSJani Nikula kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU) 2279e52347bdSJani Nikula for all guests. 2280e52347bdSJani Nikula Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. 2281e52347bdSJani Nikula 2282d8b369c4SDavid Brazdil kvm-arm.mode= 2283d8b369c4SDavid Brazdil [KVM,ARM] Select one of KVM/arm64's modes of operation. 2284d8b369c4SDavid Brazdil 22851945a067SMarc Zyngier nvhe: Standard nVHE-based mode, without support for 22861945a067SMarc Zyngier protected guests. 22871945a067SMarc Zyngier 2288d8b369c4SDavid Brazdil protected: nVHE-based mode with support for guests whose 2289d8b369c4SDavid Brazdil state is kept private from the host. 2290d8b369c4SDavid Brazdil Not valid if the kernel is running in EL2. 2291d8b369c4SDavid Brazdil 2292d8b369c4SDavid Brazdil Defaults to VHE/nVHE based on hardware support and 2293d8b369c4SDavid Brazdil the value of CONFIG_ARM64_VHE. 2294d8b369c4SDavid Brazdil 2295e23f62f7SMarc Zyngier kvm-arm.vgic_v3_group0_trap= 2296e23f62f7SMarc Zyngier [KVM,ARM] Trap guest accesses to GICv3 group-0 2297e23f62f7SMarc Zyngier system registers 2298e23f62f7SMarc Zyngier 2299182936eeSMarc Zyngier kvm-arm.vgic_v3_group1_trap= 2300182936eeSMarc Zyngier [KVM,ARM] Trap guest accesses to GICv3 group-1 2301182936eeSMarc Zyngier system registers 2302182936eeSMarc Zyngier 2303ff89511eSMarc Zyngier kvm-arm.vgic_v3_common_trap= 2304ff89511eSMarc Zyngier [KVM,ARM] Trap guest accesses to GICv3 common 2305ff89511eSMarc Zyngier system registers 2306ff89511eSMarc Zyngier 2307a7546054SMarc Zyngier kvm-arm.vgic_v4_enable= 2308a7546054SMarc Zyngier [KVM,ARM] Allow use of GICv4 for direct injection of 2309a7546054SMarc Zyngier LPIs. 2310a7546054SMarc Zyngier 2311aed26eebSSatheesh Rajendran kvm_cma_resv_ratio=n [PPC] 2312aed26eebSSatheesh Rajendran Reserves given percentage from system memory area for 2313aed26eebSSatheesh Rajendran contiguous memory allocation for KVM hash pagetable 2314aed26eebSSatheesh Rajendran allocation. 2315aed26eebSSatheesh Rajendran By default it reserves 5% of total system memory. 2316aed26eebSSatheesh Rajendran Format: <integer> 2317aed26eebSSatheesh Rajendran Default: 5 2318aed26eebSSatheesh Rajendran 2319e52347bdSJani Nikula kvm-intel.ept= [KVM,Intel] Disable extended page tables 2320e52347bdSJani Nikula (virtualized MMU) support on capable Intel chips. 2321e52347bdSJani Nikula Default is 1 (enabled) 2322e52347bdSJani Nikula 2323e52347bdSJani Nikula kvm-intel.emulate_invalid_guest_state= 2324e52347bdSJani Nikula [KVM,Intel] Enable emulation of invalid guest states 2325e52347bdSJani Nikula Default is 0 (disabled) 2326e52347bdSJani Nikula 2327e52347bdSJani Nikula kvm-intel.flexpriority= 2328e52347bdSJani Nikula [KVM,Intel] Disable FlexPriority feature (TPR shadow). 2329e52347bdSJani Nikula Default is 1 (enabled) 2330e52347bdSJani Nikula 2331e52347bdSJani Nikula kvm-intel.nested= 2332e52347bdSJani Nikula [KVM,Intel] Enable VMX nesting (nVMX). 2333e52347bdSJani Nikula Default is 0 (disabled) 2334e52347bdSJani Nikula 2335e52347bdSJani Nikula kvm-intel.unrestricted_guest= 2336e52347bdSJani Nikula [KVM,Intel] Disable unrestricted guest feature 2337e52347bdSJani Nikula (virtualized real and unpaged mode) on capable 2338e52347bdSJani Nikula Intel chips. Default is 1 (enabled) 2339e52347bdSJani Nikula 2340a399477eSKonrad Rzeszutek Wilk kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault 2341a399477eSKonrad Rzeszutek Wilk CVE-2018-3620. 2342a399477eSKonrad Rzeszutek Wilk 2343a399477eSKonrad Rzeszutek Wilk Valid arguments: never, cond, always 2344a399477eSKonrad Rzeszutek Wilk 2345a399477eSKonrad Rzeszutek Wilk always: L1D cache flush on every VMENTER. 2346a399477eSKonrad Rzeszutek Wilk cond: Flush L1D on VMENTER only when the code between 2347a399477eSKonrad Rzeszutek Wilk VMEXIT and VMENTER can leak host memory. 2348a399477eSKonrad Rzeszutek Wilk never: Disables the mitigation 2349a399477eSKonrad Rzeszutek Wilk 2350a399477eSKonrad Rzeszutek Wilk Default is cond (do L1 cache flush in specific instances) 2351a399477eSKonrad Rzeszutek Wilk 2352e52347bdSJani Nikula kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification 2353e52347bdSJani Nikula feature (tagged TLBs) on capable Intel chips. 2354e52347bdSJani Nikula Default is 1 (enabled) 2355e52347bdSJani Nikula 2356d90a7a0eSJiri Kosina l1tf= [X86] Control mitigation of the L1TF vulnerability on 2357d90a7a0eSJiri Kosina affected CPUs 2358d90a7a0eSJiri Kosina 2359d90a7a0eSJiri Kosina The kernel PTE inversion protection is unconditionally 2360d90a7a0eSJiri Kosina enabled and cannot be disabled. 2361d90a7a0eSJiri Kosina 2362d90a7a0eSJiri Kosina full 2363d90a7a0eSJiri Kosina Provides all available mitigations for the 2364d90a7a0eSJiri Kosina L1TF vulnerability. Disables SMT and 2365d90a7a0eSJiri Kosina enables all mitigations in the 2366d90a7a0eSJiri Kosina hypervisors, i.e. unconditional L1D flush. 2367d90a7a0eSJiri Kosina 2368d90a7a0eSJiri Kosina SMT control and L1D flush control via the 2369d90a7a0eSJiri Kosina sysfs interface is still possible after 2370d90a7a0eSJiri Kosina boot. Hypervisors will issue a warning 2371d90a7a0eSJiri Kosina when the first VM is started in a 2372d90a7a0eSJiri Kosina potentially insecure configuration, 2373d90a7a0eSJiri Kosina i.e. SMT enabled or L1D flush disabled. 2374d90a7a0eSJiri Kosina 2375d90a7a0eSJiri Kosina full,force 2376d90a7a0eSJiri Kosina Same as 'full', but disables SMT and L1D 2377d90a7a0eSJiri Kosina flush runtime control. Implies the 2378d90a7a0eSJiri Kosina 'nosmt=force' command line option. 2379d90a7a0eSJiri Kosina (i.e. sysfs control of SMT is disabled.) 2380d90a7a0eSJiri Kosina 2381d90a7a0eSJiri Kosina flush 2382d90a7a0eSJiri Kosina Leaves SMT enabled and enables the default 2383d90a7a0eSJiri Kosina hypervisor mitigation, i.e. conditional 2384d90a7a0eSJiri Kosina L1D flush. 2385d90a7a0eSJiri Kosina 2386d90a7a0eSJiri Kosina SMT control and L1D flush control via the 2387d90a7a0eSJiri Kosina sysfs interface is still possible after 2388d90a7a0eSJiri Kosina boot. Hypervisors will issue a warning 2389d90a7a0eSJiri Kosina when the first VM is started in a 2390d90a7a0eSJiri Kosina potentially insecure configuration, 2391d90a7a0eSJiri Kosina i.e. SMT enabled or L1D flush disabled. 2392d90a7a0eSJiri Kosina 2393d90a7a0eSJiri Kosina flush,nosmt 2394d90a7a0eSJiri Kosina 2395d90a7a0eSJiri Kosina Disables SMT and enables the default 2396d90a7a0eSJiri Kosina hypervisor mitigation. 2397d90a7a0eSJiri Kosina 2398d90a7a0eSJiri Kosina SMT control and L1D flush control via the 2399d90a7a0eSJiri Kosina sysfs interface is still possible after 2400d90a7a0eSJiri Kosina boot. Hypervisors will issue a warning 2401d90a7a0eSJiri Kosina when the first VM is started in a 2402d90a7a0eSJiri Kosina potentially insecure configuration, 2403d90a7a0eSJiri Kosina i.e. SMT enabled or L1D flush disabled. 2404d90a7a0eSJiri Kosina 2405d90a7a0eSJiri Kosina flush,nowarn 2406d90a7a0eSJiri Kosina Same as 'flush', but hypervisors will not 2407d90a7a0eSJiri Kosina warn when a VM is started in a potentially 2408d90a7a0eSJiri Kosina insecure configuration. 2409d90a7a0eSJiri Kosina 2410d90a7a0eSJiri Kosina off 2411d90a7a0eSJiri Kosina Disables hypervisor mitigations and doesn't 2412d90a7a0eSJiri Kosina emit any warnings. 24135b5e4d62SMichal Hocko It also drops the swap size and available 24145b5e4d62SMichal Hocko RAM limit restriction on both hypervisor and 24155b5e4d62SMichal Hocko bare metal. 2416d90a7a0eSJiri Kosina 2417d90a7a0eSJiri Kosina Default is 'flush'. 2418d90a7a0eSJiri Kosina 241965fd4cb6SThomas Gleixner For details see: Documentation/admin-guide/hw-vuln/l1tf.rst 2420d90a7a0eSJiri Kosina 2421e52347bdSJani Nikula l2cr= [PPC] 2422e52347bdSJani Nikula 2423e52347bdSJani Nikula l3cr= [PPC] 2424e52347bdSJani Nikula 2425e52347bdSJani Nikula lapic [X86-32,APIC] Enable the local APIC even if BIOS 2426e52347bdSJani Nikula disabled it. 2427e52347bdSJani Nikula 2428622381e6SRandy Dunlap lapic= [X86,APIC] Do not use TSC deadline 2429e52347bdSJani Nikula value for LAPIC timer one-shot implementation. Default 2430e52347bdSJani Nikula back to the programmable timer unit in the LAPIC. 2431622381e6SRandy Dunlap Format: notscdeadline 2432e52347bdSJani Nikula 2433e52347bdSJani Nikula lapic_timer_c2_ok [X86,APIC] trust the local apic timer 2434e52347bdSJani Nikula in C2 power state. 2435e52347bdSJani Nikula 2436e52347bdSJani Nikula libata.dma= [LIBATA] DMA control 2437e52347bdSJani Nikula libata.dma=0 Disable all PATA and SATA DMA 2438e52347bdSJani Nikula libata.dma=1 PATA and SATA Disk DMA only 2439e52347bdSJani Nikula libata.dma=2 ATAPI (CDROM) DMA only 2440e52347bdSJani Nikula libata.dma=4 Compact Flash DMA only 2441e52347bdSJani Nikula Combinations also work, so libata.dma=3 enables DMA 2442e52347bdSJani Nikula for disks and CDROMs, but not CFs. 2443e52347bdSJani Nikula 2444e52347bdSJani Nikula libata.ignore_hpa= [LIBATA] Ignore HPA limit 2445e52347bdSJani Nikula libata.ignore_hpa=0 keep BIOS limits (default) 2446e52347bdSJani Nikula libata.ignore_hpa=1 ignore limits, using full disk 2447e52347bdSJani Nikula 2448e52347bdSJani Nikula libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume 2449e52347bdSJani Nikula when set. 2450e52347bdSJani Nikula Format: <int> 2451e52347bdSJani Nikula 245225942e5eSRandy Dunlap libata.force= [LIBATA] Force configurations. The format is comma- 2453e52347bdSJani Nikula separated list of "[ID:]VAL" where ID is 2454e52347bdSJani Nikula PORT[.DEVICE]. PORT and DEVICE are decimal numbers 2455e52347bdSJani Nikula matching port, link or device. Basically, it matches 2456e52347bdSJani Nikula the ATA ID string printed on console by libata. If 2457e52347bdSJani Nikula the whole ID part is omitted, the last PORT and DEVICE 2458e52347bdSJani Nikula values are used. If ID hasn't been specified yet, the 2459e52347bdSJani Nikula configuration applies to all ports, links and devices. 2460e52347bdSJani Nikula 2461e52347bdSJani Nikula If only DEVICE is omitted, the parameter applies to 2462e52347bdSJani Nikula the port and all links and devices behind it. DEVICE 2463e52347bdSJani Nikula number of 0 either selects the first device or the 2464e52347bdSJani Nikula first fan-out link behind PMP device. It does not 2465e52347bdSJani Nikula select the host link. DEVICE number of 15 selects the 2466e52347bdSJani Nikula host link and device attached to it. 2467e52347bdSJani Nikula 2468e52347bdSJani Nikula The VAL specifies the configuration to force. As long 2469e52347bdSJani Nikula as there's no ambiguity shortcut notation is allowed. 2470e52347bdSJani Nikula For example, both 1.5 and 1.5G would work for 1.5Gbps. 2471e52347bdSJani Nikula The following configurations can be forced. 2472e52347bdSJani Nikula 2473e52347bdSJani Nikula * Cable type: 40c, 80c, short40c, unk, ign or sata. 2474e52347bdSJani Nikula Any ID with matching PORT is used. 2475e52347bdSJani Nikula 2476e52347bdSJani Nikula * SATA link speed limit: 1.5Gbps or 3.0Gbps. 2477e52347bdSJani Nikula 2478e52347bdSJani Nikula * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. 2479e52347bdSJani Nikula udma[/][16,25,33,44,66,100,133] notation is also 2480e52347bdSJani Nikula allowed. 2481e52347bdSJani Nikula 2482e52347bdSJani Nikula * [no]ncq: Turn on or off NCQ. 2483e52347bdSJani Nikula 2484e52347bdSJani Nikula * [no]ncqtrim: Turn off queued DSM TRIM. 2485e52347bdSJani Nikula 2486e52347bdSJani Nikula * nohrst, nosrst, norst: suppress hard, soft 2487e52347bdSJani Nikula and both resets. 2488e52347bdSJani Nikula 2489e52347bdSJani Nikula * rstonce: only attempt one reset during 2490e52347bdSJani Nikula hot-unplug link recovery 2491e52347bdSJani Nikula 2492e52347bdSJani Nikula * dump_id: dump IDENTIFY data. 2493e52347bdSJani Nikula 2494e52347bdSJani Nikula * atapi_dmadir: Enable ATAPI DMADIR bridge support 2495e52347bdSJani Nikula 2496e52347bdSJani Nikula * disable: Disable this device. 2497e52347bdSJani Nikula 2498e52347bdSJani Nikula If there are multiple matching configurations changing 2499e52347bdSJani Nikula the same attribute, the last one is used. 2500e52347bdSJani Nikula 2501e52347bdSJani Nikula memblock=debug [KNL] Enable memblock debug messages. 2502e52347bdSJani Nikula 25036b99e6e6SRandy Dunlap load_ramdisk= [RAM] [Deprecated] 2504e52347bdSJani Nikula 2505e52347bdSJani Nikula lockd.nlm_grace_period=P [NFS] Assign grace period. 2506e52347bdSJani Nikula Format: <integer> 2507e52347bdSJani Nikula 2508e52347bdSJani Nikula lockd.nlm_tcpport=N [NFS] Assign TCP port. 2509e52347bdSJani Nikula Format: <integer> 2510e52347bdSJani Nikula 2511e52347bdSJani Nikula lockd.nlm_timeout=T [NFS] Assign timeout value. 2512e52347bdSJani Nikula Format: <integer> 2513e52347bdSJani Nikula 2514e52347bdSJani Nikula lockd.nlm_udpport=M [NFS] Assign UDP port. 2515e52347bdSJani Nikula Format: <integer> 2516e52347bdSJani Nikula 2517000d388eSMatthew Garrett lockdown= [SECURITY] 2518000d388eSMatthew Garrett { integrity | confidentiality } 2519000d388eSMatthew Garrett Enable the kernel lockdown feature. If set to 2520000d388eSMatthew Garrett integrity, kernel features that allow userland to 2521000d388eSMatthew Garrett modify the running kernel are disabled. If set to 2522000d388eSMatthew Garrett confidentiality, kernel features that allow userland 2523000d388eSMatthew Garrett to extract confidential information from the kernel 2524000d388eSMatthew Garrett are also disabled. 2525000d388eSMatthew Garrett 2526e52347bdSJani Nikula locktorture.nreaders_stress= [KNL] 2527e52347bdSJani Nikula Set the number of locking read-acquisition kthreads. 2528e52347bdSJani Nikula Defaults to being automatically set based on the 2529e52347bdSJani Nikula number of online CPUs. 2530e52347bdSJani Nikula 2531e52347bdSJani Nikula locktorture.nwriters_stress= [KNL] 2532e52347bdSJani Nikula Set the number of locking write-acquisition kthreads. 2533e52347bdSJani Nikula 2534e52347bdSJani Nikula locktorture.onoff_holdoff= [KNL] 2535e52347bdSJani Nikula Set time (s) after boot for CPU-hotplug testing. 2536e52347bdSJani Nikula 2537e52347bdSJani Nikula locktorture.onoff_interval= [KNL] 2538e52347bdSJani Nikula Set time (s) between CPU-hotplug operations, or 2539e52347bdSJani Nikula zero to disable CPU-hotplug testing. 2540e52347bdSJani Nikula 2541e52347bdSJani Nikula locktorture.shuffle_interval= [KNL] 2542e52347bdSJani Nikula Set task-shuffle interval (jiffies). Shuffling 2543e52347bdSJani Nikula tasks allows some CPUs to go into dyntick-idle 2544e52347bdSJani Nikula mode during the locktorture test. 2545e52347bdSJani Nikula 2546e52347bdSJani Nikula locktorture.shutdown_secs= [KNL] 2547e52347bdSJani Nikula Set time (s) after boot system shutdown. This 2548e52347bdSJani Nikula is useful for hands-off automated testing. 2549e52347bdSJani Nikula 2550e52347bdSJani Nikula locktorture.stat_interval= [KNL] 2551e52347bdSJani Nikula Time (s) between statistics printk()s. 2552e52347bdSJani Nikula 2553e52347bdSJani Nikula locktorture.stutter= [KNL] 2554e52347bdSJani Nikula Time (s) to stutter testing, for example, 2555e52347bdSJani Nikula specifying five seconds causes the test to run for 2556e52347bdSJani Nikula five seconds, wait for five seconds, and so on. 2557e52347bdSJani Nikula This tests the locking primitive's ability to 2558e52347bdSJani Nikula transition abruptly to and from idle. 2559e52347bdSJani Nikula 2560e52347bdSJani Nikula locktorture.torture_type= [KNL] 2561e52347bdSJani Nikula Specify the locking implementation to test. 2562e52347bdSJani Nikula 2563e52347bdSJani Nikula locktorture.verbose= [KNL] 2564e52347bdSJani Nikula Enable additional printk() statements. 2565e52347bdSJani Nikula 2566e52347bdSJani Nikula logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver 2567e52347bdSJani Nikula Format: <irq> 2568e52347bdSJani Nikula 2569e52347bdSJani Nikula loglevel= All Kernel Messages with a loglevel smaller than the 2570e52347bdSJani Nikula console loglevel will be printed to the console. It can 2571e52347bdSJani Nikula also be changed with klogd or other programs. The 2572e52347bdSJani Nikula loglevels are defined as follows: 2573e52347bdSJani Nikula 2574e52347bdSJani Nikula 0 (KERN_EMERG) system is unusable 2575e52347bdSJani Nikula 1 (KERN_ALERT) action must be taken immediately 2576e52347bdSJani Nikula 2 (KERN_CRIT) critical conditions 2577e52347bdSJani Nikula 3 (KERN_ERR) error conditions 2578e52347bdSJani Nikula 4 (KERN_WARNING) warning conditions 2579e52347bdSJani Nikula 5 (KERN_NOTICE) normal but significant condition 2580e52347bdSJani Nikula 6 (KERN_INFO) informational 2581e52347bdSJani Nikula 7 (KERN_DEBUG) debug-level messages 2582e52347bdSJani Nikula 2583e52347bdSJani Nikula log_buf_len=n[KMG] Sets the size of the printk ring buffer, 2584e52347bdSJani Nikula in bytes. n must be a power of two and greater 2585e52347bdSJani Nikula than the minimal size. The minimal size is defined 2586e52347bdSJani Nikula by LOG_BUF_SHIFT kernel config parameter. There is 2587e52347bdSJani Nikula also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter 2588e52347bdSJani Nikula that allows to increase the default size depending on 2589e52347bdSJani Nikula the number of CPUs. See init/Kconfig for more details. 2590e52347bdSJani Nikula 2591e52347bdSJani Nikula logo.nologo [FB] Disables display of the built-in Linux logo. 2592e52347bdSJani Nikula This may be used to provide more screen space for 2593e52347bdSJani Nikula kernel log messages and is useful when debugging 2594e52347bdSJani Nikula kernel boot problems. 2595e52347bdSJani Nikula 2596e52347bdSJani Nikula lp=0 [LP] Specify parallel ports to use, e.g, 2597e52347bdSJani Nikula lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 2598e52347bdSJani Nikula lp=reset first parallel port). 'lp=0' disables the 2599e52347bdSJani Nikula lp=auto printer driver. 'lp=reset' (which can be 2600e52347bdSJani Nikula specified in addition to the ports) causes 2601e52347bdSJani Nikula attached printers to be reset. Using 2602e52347bdSJani Nikula lp=port1,port2,... specifies the parallel ports 2603e52347bdSJani Nikula to associate lp devices with, starting with 2604e52347bdSJani Nikula lp0. A port specification may be 'none' to skip 2605e52347bdSJani Nikula that lp device, or a parport name such as 2606e52347bdSJani Nikula 'parport0'. Specifying 'lp=auto' instead of a 2607e52347bdSJani Nikula port specification list means that device IDs 2608e52347bdSJani Nikula from each port should be examined, to see if 2609e52347bdSJani Nikula an IEEE 1284-compliant printer is attached; if 2610e52347bdSJani Nikula so, the driver will manage that printer. 2611e52347bdSJani Nikula See also header of drivers/char/lp.c. 2612e52347bdSJani Nikula 2613e52347bdSJani Nikula lpj=n [KNL] 2614e52347bdSJani Nikula Sets loops_per_jiffy to given constant, thus avoiding 2615e52347bdSJani Nikula time-consuming boot-time autodetection (up to 250 ms per 2616e52347bdSJani Nikula CPU). 0 enables autodetection (default). To determine 2617e52347bdSJani Nikula the correct value for your kernel, boot with normal 2618e52347bdSJani Nikula autodetection and see what value is printed. Note that 2619e52347bdSJani Nikula on SMP systems the preset will be applied to all CPUs, 2620e52347bdSJani Nikula which is likely to cause problems if your CPUs need 2621e52347bdSJani Nikula significantly divergent settings. An incorrect value 2622e52347bdSJani Nikula will cause delays in the kernel to be wrong, leading to 2623e52347bdSJani Nikula unpredictable I/O errors and other breakage. Although 2624e52347bdSJani Nikula unlikely, in the extreme case this might damage your 2625e52347bdSJani Nikula hardware. 2626e52347bdSJani Nikula 2627e52347bdSJani Nikula ltpc= [NET] 2628e52347bdSJani Nikula Format: <io>,<irq>,<dma> 2629e52347bdSJani Nikula 26309b8c7c14SKees Cook lsm.debug [SECURITY] Enable LSM initialization debugging output. 26319b8c7c14SKees Cook 263279f7865dSKees Cook lsm=lsm1,...,lsmN 263379f7865dSKees Cook [SECURITY] Choose order of LSM initialization. This 263489a9684eSKees Cook overrides CONFIG_LSM, and the "security=" parameter. 263579f7865dSKees Cook 2636e52347bdSJani Nikula machvec= [IA-64] Force the use of a particular machine-vector 2637e52347bdSJani Nikula (machvec) in a generic kernel. 2638df43acacSChristoph Hellwig Example: machvec=hpzx1 2639e52347bdSJani Nikula 264042769488SRandy Dunlap machtype= [Loongson] Share the same kernel image file between 264142769488SRandy Dunlap different yeeloong laptops. 2642e52347bdSJani Nikula Example: machtype=lemote-yeeloong-2f-7inch 2643e52347bdSJani Nikula 2644e52347bdSJani Nikula max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater 2645e52347bdSJani Nikula than or equal to this physical address is ignored. 2646e52347bdSJani Nikula 2647e52347bdSJani Nikula maxcpus= [SMP] Maximum number of processors that an SMP kernel 2648e52347bdSJani Nikula will bring up during bootup. maxcpus=n : n >= 0 limits 2649e52347bdSJani Nikula the kernel to bring up 'n' processors. Surely after 2650e52347bdSJani Nikula bootup you can bring up the other plugged cpu by executing 2651e52347bdSJani Nikula "echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus 2652e52347bdSJani Nikula only takes effect during system bootup. 2653e52347bdSJani Nikula While n=0 is a special case, it is equivalent to "nosmp", 2654e52347bdSJani Nikula which also disables the IO APIC. 2655e52347bdSJani Nikula 2656e52347bdSJani Nikula max_loop= [LOOP] The number of loop block devices that get 2657e52347bdSJani Nikula (loop.max_loop) unconditionally pre-created at init time. The default 2658e52347bdSJani Nikula number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead 2659e52347bdSJani Nikula of statically allocating a predefined number, loop 2660e52347bdSJani Nikula devices can be requested on-demand with the 2661e52347bdSJani Nikula /dev/loop-control interface. 2662e52347bdSJani Nikula 2663e52347bdSJani Nikula mce [X86-32] Machine Check Exception 2664e52347bdSJani Nikula 2665cb1aaebeSMauro Carvalho Chehab mce=option [X86-64] See Documentation/x86/x86_64/boot-options.rst 2666e52347bdSJani Nikula 2667e52347bdSJani Nikula md= [HW] RAID subsystems devices and level 2668e52347bdSJani Nikula See Documentation/admin-guide/md.rst. 2669e52347bdSJani Nikula 2670e52347bdSJani Nikula mdacon= [MDA] 2671e52347bdSJani Nikula Format: <first>,<last> 2672e52347bdSJani Nikula Specifies range of consoles to be captured by the MDA. 2673e52347bdSJani Nikula 2674bc124170SThomas Gleixner mds= [X86,INTEL] 2675bc124170SThomas Gleixner Control mitigation for the Micro-architectural Data 2676bc124170SThomas Gleixner Sampling (MDS) vulnerability. 2677bc124170SThomas Gleixner 2678bc124170SThomas Gleixner Certain CPUs are vulnerable to an exploit against CPU 2679bc124170SThomas Gleixner internal buffers which can forward information to a 2680bc124170SThomas Gleixner disclosure gadget under certain conditions. 2681bc124170SThomas Gleixner 2682bc124170SThomas Gleixner In vulnerable processors, the speculatively 2683bc124170SThomas Gleixner forwarded data can be used in a cache side channel 2684bc124170SThomas Gleixner attack, to access data to which the attacker does 2685bc124170SThomas Gleixner not have direct access. 2686bc124170SThomas Gleixner 2687bc124170SThomas Gleixner This parameter controls the MDS mitigation. The 2688bc124170SThomas Gleixner options are: 2689bc124170SThomas Gleixner 2690bc124170SThomas Gleixner full - Enable MDS mitigation on vulnerable CPUs 2691d71eb0ceSJosh Poimboeuf full,nosmt - Enable MDS mitigation and disable 2692d71eb0ceSJosh Poimboeuf SMT on vulnerable CPUs 2693bc124170SThomas Gleixner off - Unconditionally disable MDS mitigation 2694bc124170SThomas Gleixner 269564870ed1SWaiman Long On TAA-affected machines, mds=off can be prevented by 269664870ed1SWaiman Long an active TAA mitigation as both vulnerabilities are 269764870ed1SWaiman Long mitigated with the same mechanism so in order to disable 269864870ed1SWaiman Long this mitigation, you need to specify tsx_async_abort=off 269964870ed1SWaiman Long too. 270064870ed1SWaiman Long 2701bc124170SThomas Gleixner Not specifying this option is equivalent to 2702bc124170SThomas Gleixner mds=full. 2703bc124170SThomas Gleixner 27045999bbe7SThomas Gleixner For details see: Documentation/admin-guide/hw-vuln/mds.rst 27055999bbe7SThomas Gleixner 2706e52347bdSJani Nikula mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory 2707f3cd4c86SBaoquan He Amount of memory to be used in cases as follows: 2708f3cd4c86SBaoquan He 2709f3cd4c86SBaoquan He 1 for test; 2710f3cd4c86SBaoquan He 2 when the kernel is not able to see the whole system memory; 2711f3cd4c86SBaoquan He 3 memory that lies after 'mem=' boundary is excluded from 2712f3cd4c86SBaoquan He the hypervisor, then assigned to KVM guests. 2713f3cd4c86SBaoquan He 2714e52347bdSJani Nikula [X86] Work as limiting max address. Use together 2715e52347bdSJani Nikula with memmap= to avoid physical address space collisions. 2716e52347bdSJani Nikula Without memmap= PCI devices could be placed at addresses 2717e52347bdSJani Nikula belonging to unused RAM. 2718e52347bdSJani Nikula 2719f3cd4c86SBaoquan He Note that this only takes effects during boot time since 2720f3cd4c86SBaoquan He in above case 3, memory may need be hot added after boot 2721f3cd4c86SBaoquan He if system memory of hypervisor is not sufficient. 2722f3cd4c86SBaoquan He 2723e52347bdSJani Nikula mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel 2724e52347bdSJani Nikula memory. 2725e52347bdSJani Nikula 2726e52347bdSJani Nikula memchunk=nn[KMG] 2727e52347bdSJani Nikula [KNL,SH] Allow user to override the default size for 2728e52347bdSJani Nikula per-device physically contiguous DMA buffers. 2729e52347bdSJani Nikula 2730e52347bdSJani Nikula memhp_default_state=online/offline 2731e52347bdSJani Nikula [KNL] Set the initial state for the memory hotplug 2732e52347bdSJani Nikula onlining policy. If not specified, the default value is 2733e52347bdSJani Nikula set according to the 2734e52347bdSJani Nikula CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config 2735e52347bdSJani Nikula option. 2736cb1aaebeSMauro Carvalho Chehab See Documentation/admin-guide/mm/memory-hotplug.rst. 2737e52347bdSJani Nikula 2738e52347bdSJani Nikula memmap=exactmap [KNL,X86] Enable setting of an exact 2739e52347bdSJani Nikula E820 memory map, as specified by the user. 2740e52347bdSJani Nikula Such memmap=exactmap lines can be constructed based on 2741e52347bdSJani Nikula BIOS output or other requirements. See the memmap=nn@ss 2742e52347bdSJani Nikula option description. 2743e52347bdSJani Nikula 2744e52347bdSJani Nikula memmap=nn[KMG]@ss[KMG] 27454c8e3de4SBarry Song [KNL, X86, MIPS, XTENSA] Force usage of a specific region of memory. 2746e52347bdSJani Nikula Region of memory to be used is from ss to ss+nn. 27478fcc9bc3SBaoquan He If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG], 27488fcc9bc3SBaoquan He which limits max address to nn[KMG]. 27498fcc9bc3SBaoquan He Multiple different regions can be specified, 27508fcc9bc3SBaoquan He comma delimited. 27518fcc9bc3SBaoquan He Example: 27528fcc9bc3SBaoquan He memmap=100M@2G,100M#3G,1G!1024G 2753e52347bdSJani Nikula 2754e52347bdSJani Nikula memmap=nn[KMG]#ss[KMG] 2755e52347bdSJani Nikula [KNL,ACPI] Mark specific memory as ACPI data. 2756e52347bdSJani Nikula Region of memory to be marked is from ss to ss+nn. 2757e52347bdSJani Nikula 2758e52347bdSJani Nikula memmap=nn[KMG]$ss[KMG] 2759e52347bdSJani Nikula [KNL,ACPI] Mark specific memory as reserved. 2760e52347bdSJani Nikula Region of memory to be reserved is from ss to ss+nn. 2761e52347bdSJani Nikula Example: Exclude memory from 0x18690000-0x1869ffff 2762e52347bdSJani Nikula memmap=64K$0x18690000 2763e52347bdSJani Nikula or 2764e52347bdSJani Nikula memmap=0x10000$0x18690000 27658fcc9bc3SBaoquan He Some bootloaders may need an escape character before '$', 27668fcc9bc3SBaoquan He like Grub2, otherwise '$' and the following number 27678fcc9bc3SBaoquan He will be eaten. 2768e52347bdSJani Nikula 2769e52347bdSJani Nikula memmap=nn[KMG]!ss[KMG] 2770e52347bdSJani Nikula [KNL,X86] Mark specific memory as protected. 2771e52347bdSJani Nikula Region of memory to be used, from ss to ss+nn. 2772e52347bdSJani Nikula The memory region may be marked as e820 type 12 (0xc) 2773e52347bdSJani Nikula and is NVDIMM or ADR memory. 2774e52347bdSJani Nikula 2775ef61f8a3SJan H. Schönherr memmap=<size>%<offset>-<oldtype>+<newtype> 2776ef61f8a3SJan H. Schönherr [KNL,ACPI] Convert memory within the specified region 2777ef61f8a3SJan H. Schönherr from <oldtype> to <newtype>. If "-<oldtype>" is left 2778ef61f8a3SJan H. Schönherr out, the whole region will be marked as <newtype>, 2779ef61f8a3SJan H. Schönherr even if previously unavailable. If "+<newtype>" is left 2780ef61f8a3SJan H. Schönherr out, matching memory will be removed. Types are 2781ef61f8a3SJan H. Schönherr specified as e820 types, e.g., 1 = RAM, 2 = reserved, 2782ef61f8a3SJan H. Schönherr 3 = ACPI, 12 = PRAM. 2783ef61f8a3SJan H. Schönherr 2784e52347bdSJani Nikula memory_corruption_check=0/1 [X86] 2785e52347bdSJani Nikula Some BIOSes seem to corrupt the first 64k of 2786e52347bdSJani Nikula memory when doing things like suspend/resume. 2787e52347bdSJani Nikula Setting this option will scan the memory 2788e52347bdSJani Nikula looking for corruption. Enabling this will 2789e52347bdSJani Nikula both detect corruption and prevent the kernel 2790e52347bdSJani Nikula from using the memory being corrupted. 2791e52347bdSJani Nikula However, its intended as a diagnostic tool; if 2792e52347bdSJani Nikula repeatable BIOS-originated corruption always 2793e52347bdSJani Nikula affects the same memory, you can use memmap= 2794e52347bdSJani Nikula to prevent the kernel from using that memory. 2795e52347bdSJani Nikula 2796e52347bdSJani Nikula memory_corruption_check_size=size [X86] 2797e52347bdSJani Nikula By default it checks for corruption in the low 2798e52347bdSJani Nikula 64k, making this memory unavailable for normal 2799e52347bdSJani Nikula use. Use this parameter to scan for 2800e52347bdSJani Nikula corruption in more or less memory. 2801e52347bdSJani Nikula 2802e52347bdSJani Nikula memory_corruption_check_period=seconds [X86] 2803e52347bdSJani Nikula By default it checks for corruption every 60 2804e52347bdSJani Nikula seconds. Use this parameter to check at some 2805e52347bdSJani Nikula other rate. 0 disables periodic checking. 2806e52347bdSJani Nikula 2807d90fe2acSChristophe Leroy memtest= [KNL,X86,ARM,PPC] Enable memtest 2808e52347bdSJani Nikula Format: <integer> 2809e52347bdSJani Nikula default : 0 <disable> 2810e52347bdSJani Nikula Specifies the number of memtest passes to be 2811e52347bdSJani Nikula performed. Each pass selects another test 2812e52347bdSJani Nikula pattern from a given set of patterns. Memtest 2813e52347bdSJani Nikula fills the memory with this pattern, validates 2814e52347bdSJani Nikula memory contents and reserves bad memory 2815e52347bdSJani Nikula regions that are detected. 2816e52347bdSJani Nikula 2817c262f3b9STom Lendacky mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control 2818c262f3b9STom Lendacky Valid arguments: on, off 2819c262f3b9STom Lendacky Default (depends on kernel configuration option): 2820c262f3b9STom Lendacky on (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y) 2821c262f3b9STom Lendacky off (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n) 2822c262f3b9STom Lendacky mem_encrypt=on: Activate SME 2823c262f3b9STom Lendacky mem_encrypt=off: Do not activate SME 2824c262f3b9STom Lendacky 28252f5947dfSChristoph Hellwig Refer to Documentation/virt/kvm/amd-memory-encryption.rst 2826c262f3b9STom Lendacky for details on when memory encryption can be activated. 2827c262f3b9STom Lendacky 28287b9dc3f7SLinus Torvalds mem_sleep_default= [SUSPEND] Default system suspend mode: 28297b9dc3f7SLinus Torvalds s2idle - Suspend-To-Idle 28307b9dc3f7SLinus Torvalds shallow - Power-On Suspend or equivalent (if supported) 28317b9dc3f7SLinus Torvalds deep - Suspend-To-RAM or equivalent (if supported) 283258e7cb9eSRafael J. Wysocki See Documentation/admin-guide/pm/sleep-states.rst. 28337b9dc3f7SLinus Torvalds 2834e52347bdSJani Nikula meye.*= [HW] Set MotionEye Camera parameters 283532e2eae2SMauro Carvalho Chehab See Documentation/admin-guide/media/meye.rst. 2836e52347bdSJani Nikula 2837e52347bdSJani Nikula mfgpt_irq= [IA-32] Specify the IRQ to use for the 2838e52347bdSJani Nikula Multi-Function General Purpose Timers on AMD Geode 2839e52347bdSJani Nikula platforms. 2840e52347bdSJani Nikula 2841e52347bdSJani Nikula mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when 2842e52347bdSJani Nikula the BIOS has incorrectly applied a workaround. TinyBIOS 2843e52347bdSJani Nikula version 0.98 is known to be affected, 0.99 fixes the 2844e52347bdSJani Nikula problem by letting the user disable the workaround. 2845e52347bdSJani Nikula 2846e52347bdSJani Nikula mga= [HW,DRM] 2847e52347bdSJani Nikula 2848e52347bdSJani Nikula min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this 2849e52347bdSJani Nikula physical address is ignored. 2850e52347bdSJani Nikula 2851e52347bdSJani Nikula mini2440= [ARM,HW,KNL] 2852e52347bdSJani Nikula Format:[0..2][b][c][t] 2853e52347bdSJani Nikula Default: "0tb" 2854e52347bdSJani Nikula MINI2440 configuration specification: 2855e52347bdSJani Nikula 0 - The attached screen is the 3.5" TFT 2856e52347bdSJani Nikula 1 - The attached screen is the 7" TFT 2857e52347bdSJani Nikula 2 - The VGA Shield is attached (1024x768) 2858e52347bdSJani Nikula Leaving out the screen size parameter will not load 2859e52347bdSJani Nikula the TFT driver, and the framebuffer will be left 2860e52347bdSJani Nikula unconfigured. 2861e52347bdSJani Nikula b - Enable backlight. The TFT backlight pin will be 2862e52347bdSJani Nikula linked to the kernel VESA blanking code and a GPIO 2863e52347bdSJani Nikula LED. This parameter is not necessary when using the 2864e52347bdSJani Nikula VGA shield. 2865e52347bdSJani Nikula c - Enable the s3c camera interface. 2866e52347bdSJani Nikula t - Reserved for enabling touchscreen support. The 2867e52347bdSJani Nikula touchscreen support is not enabled in the mainstream 2868e52347bdSJani Nikula kernel as of 2.6.30, a preliminary port can be found 2869e52347bdSJani Nikula in the "bleeding edge" mini2440 support kernel at 28706b2484e1SAlexander A. Klimov https://repo.or.cz/w/linux-2.6/mini2440.git 2871e52347bdSJani Nikula 287298af8452SJosh Poimboeuf mitigations= 2873a111b7c0SJosh Poimboeuf [X86,PPC,S390,ARM64] Control optional mitigations for 2874a111b7c0SJosh Poimboeuf CPU vulnerabilities. This is a set of curated, 2875d68be4c4SJosh Poimboeuf arch-independent options, each of which is an 2876d68be4c4SJosh Poimboeuf aggregation of existing arch-specific options. 287798af8452SJosh Poimboeuf 287898af8452SJosh Poimboeuf off 287998af8452SJosh Poimboeuf Disable all optional CPU mitigations. This 288098af8452SJosh Poimboeuf improves system performance, but it may also 288198af8452SJosh Poimboeuf expose users to several CPU vulnerabilities. 2882782e69efSJosh Poimboeuf Equivalent to: nopti [X86,PPC] 2883a111b7c0SJosh Poimboeuf kpti=0 [ARM64] 2884a2059825SJosh Poimboeuf nospectre_v1 [X86,PPC] 28850336e04aSJosh Poimboeuf nobp=0 [S390] 2886a111b7c0SJosh Poimboeuf nospectre_v2 [X86,PPC,S390,ARM64] 2887d68be4c4SJosh Poimboeuf spectre_v2_user=off [X86] 2888782e69efSJosh Poimboeuf spec_store_bypass_disable=off [X86,PPC] 2889a111b7c0SJosh Poimboeuf ssbd=force-off [ARM64] 2890d68be4c4SJosh Poimboeuf l1tf=off [X86] 28915c14068fSJosh Poimboeuf mds=off [X86] 2892a7a248c5SPawan Gupta tsx_async_abort=off [X86] 2893b8e8c830SPaolo Bonzini kvm.nx_huge_pages=off [X86] 2894f7964378SNicholas Piggin no_entry_flush [PPC] 28959a32a7e7SNicholas Piggin no_uaccess_flush [PPC] 2896b8e8c830SPaolo Bonzini 2897b8e8c830SPaolo Bonzini Exceptions: 2898b8e8c830SPaolo Bonzini This does not have any effect on 2899b8e8c830SPaolo Bonzini kvm.nx_huge_pages when 2900b8e8c830SPaolo Bonzini kvm.nx_huge_pages=force. 290198af8452SJosh Poimboeuf 290298af8452SJosh Poimboeuf auto (default) 290398af8452SJosh Poimboeuf Mitigate all CPU vulnerabilities, but leave SMT 290498af8452SJosh Poimboeuf enabled, even if it's vulnerable. This is for 290598af8452SJosh Poimboeuf users who don't want to be surprised by SMT 290698af8452SJosh Poimboeuf getting disabled across kernel upgrades, or who 290798af8452SJosh Poimboeuf have other ways of avoiding SMT-based attacks. 2908d68be4c4SJosh Poimboeuf Equivalent to: (default behavior) 290998af8452SJosh Poimboeuf 291098af8452SJosh Poimboeuf auto,nosmt 291198af8452SJosh Poimboeuf Mitigate all CPU vulnerabilities, disabling SMT 291298af8452SJosh Poimboeuf if needed. This is for users who always want to 291398af8452SJosh Poimboeuf be fully mitigated, even if it means losing SMT. 2914d68be4c4SJosh Poimboeuf Equivalent to: l1tf=flush,nosmt [X86] 29155c14068fSJosh Poimboeuf mds=full,nosmt [X86] 2916a7a248c5SPawan Gupta tsx_async_abort=full,nosmt [X86] 291798af8452SJosh Poimboeuf 2918e52347bdSJani Nikula mminit_loglevel= 2919e52347bdSJani Nikula [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this 2920e52347bdSJani Nikula parameter allows control of the logging verbosity for 2921e52347bdSJani Nikula the additional memory initialisation checks. A value 2922e52347bdSJani Nikula of 0 disables mminit logging and a level of 4 will 2923e52347bdSJani Nikula log everything. Information is printed at KERN_DEBUG 2924e52347bdSJani Nikula so loglevel=8 may also need to be specified. 2925e52347bdSJani Nikula 2926e52347bdSJani Nikula module.sig_enforce 2927e52347bdSJani Nikula [KNL] When CONFIG_MODULE_SIG is set, this means that 2928e52347bdSJani Nikula modules without (valid) signatures will fail to load. 2929e52347bdSJani Nikula Note that if CONFIG_MODULE_SIG_FORCE is set, that 2930e52347bdSJani Nikula is always true, so this option does nothing. 2931e52347bdSJani Nikula 2932e52347bdSJani Nikula module_blacklist= [KNL] Do not load a comma-separated list of 2933e52347bdSJani Nikula modules. Useful for debugging problem modules. 2934e52347bdSJani Nikula 2935e52347bdSJani Nikula mousedev.tap_time= 2936e52347bdSJani Nikula [MOUSE] Maximum time between finger touching and 2937e52347bdSJani Nikula leaving touchpad surface for touch to be considered 2938e52347bdSJani Nikula a tap and be reported as a left button click (for 2939e52347bdSJani Nikula touchpads working in absolute mode only). 2940e52347bdSJani Nikula Format: <msecs> 2941e52347bdSJani Nikula mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices 2942e52347bdSJani Nikula reporting absolute coordinates, such as tablets 2943e52347bdSJani Nikula mousedev.yres= [MOUSE] Vertical screen resolution, used for devices 2944e52347bdSJani Nikula reporting absolute coordinates, such as tablets 2945e52347bdSJani Nikula 2946a5c6d650SDavid Rientjes movablecore= [KNL,X86,IA-64,PPC] 2947a5c6d650SDavid Rientjes Format: nn[KMGTPE] | nn% 2948a5c6d650SDavid Rientjes This parameter is the complement to kernelcore=, it 2949a5c6d650SDavid Rientjes specifies the amount of memory used for migratable 2950a5c6d650SDavid Rientjes allocations. If both kernelcore and movablecore is 2951a5c6d650SDavid Rientjes specified, then kernelcore will be at *least* the 2952a5c6d650SDavid Rientjes specified value but may be more. If movablecore on its 2953a5c6d650SDavid Rientjes own is specified, the administrator must be careful 2954e52347bdSJani Nikula that the amount of memory usable for all allocations 2955e52347bdSJani Nikula is not too small. 2956e52347bdSJani Nikula 2957f70029bbSMichal Hocko movable_node [KNL] Boot-time switch to make hotplugable memory 2958f70029bbSMichal Hocko NUMA nodes to be movable. This means that the memory 2959f70029bbSMichal Hocko of such nodes will be usable only for movable 2960f70029bbSMichal Hocko allocations which rules out almost all kernel 2961f70029bbSMichal Hocko allocations. Use with caution! 2962e52347bdSJani Nikula 2963e52347bdSJani Nikula MTD_Partition= [MTD] 2964e52347bdSJani Nikula Format: <name>,<region-number>,<size>,<offset> 2965e52347bdSJani Nikula 2966e52347bdSJani Nikula MTD_Region= [MTD] Format: 2967e52347bdSJani Nikula <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] 2968e52347bdSJani Nikula 2969e52347bdSJani Nikula mtdparts= [MTD] 2970fb251124SJonathan Neuschäfer See drivers/mtd/parsers/cmdlinepart.c 2971e52347bdSJani Nikula 2972e52347bdSJani Nikula multitce=off [PPC] This parameter disables the use of the pSeries 2973e52347bdSJani Nikula firmware feature for updating multiple TCE entries 2974e52347bdSJani Nikula at a time. 2975e52347bdSJani Nikula 2976e52347bdSJani Nikula onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration 2977e52347bdSJani Nikula 2978e52347bdSJani Nikula Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] 2979e52347bdSJani Nikula 2980e52347bdSJani Nikula boundary - index of last SLC block on Flex-OneNAND. 2981e52347bdSJani Nikula The remaining blocks are configured as MLC blocks. 2982e52347bdSJani Nikula lock - Configure if Flex-OneNAND boundary should be locked. 2983e52347bdSJani Nikula Once locked, the boundary cannot be changed. 2984e52347bdSJani Nikula 1 indicates lock status, 0 indicates unlock status. 2985e52347bdSJani Nikula 2986e52347bdSJani Nikula mtdset= [ARM] 2987e52347bdSJani Nikula ARM/S3C2412 JIVE boot control 2988e52347bdSJani Nikula 29890f12999eSKrzysztof Kozlowski See arch/arm/mach-s3c/mach-jive.c 2990e52347bdSJani Nikula 2991e52347bdSJani Nikula mtouchusb.raw_coordinates= 2992e52347bdSJani Nikula [HW] Make the MicroTouch USB driver use raw coordinates 2993e52347bdSJani Nikula ('y', default) or cooked coordinates ('n') 2994e52347bdSJani Nikula 2995e52347bdSJani Nikula mtrr_chunk_size=nn[KMG] [X86] 2996e52347bdSJani Nikula used for mtrr cleanup. It is largest continuous chunk 2997e52347bdSJani Nikula that could hold holes aka. UC entries. 2998e52347bdSJani Nikula 2999e52347bdSJani Nikula mtrr_gran_size=nn[KMG] [X86] 3000e52347bdSJani Nikula Used for mtrr cleanup. It is granularity of mtrr block. 3001e52347bdSJani Nikula Default is 1. 3002e52347bdSJani Nikula Large value could prevent small alignment from 3003e52347bdSJani Nikula using up MTRRs. 3004e52347bdSJani Nikula 3005e52347bdSJani Nikula mtrr_spare_reg_nr=n [X86] 3006e52347bdSJani Nikula Format: <integer> 3007e52347bdSJani Nikula Range: 0,7 : spare reg number 3008e52347bdSJani Nikula Default : 1 3009e52347bdSJani Nikula Used for mtrr cleanup. It is spare mtrr entries number. 3010e52347bdSJani Nikula Set to 2 or more if your graphical card needs more. 3011e52347bdSJani Nikula 3012e52347bdSJani Nikula n2= [NET] SDL Inc. RISCom/N2 synchronous serial card 3013e52347bdSJani Nikula 3014e52347bdSJani Nikula netdev= [NET] Network devices parameters 3015e52347bdSJani Nikula Format: <irq>,<io>,<mem_start>,<mem_end>,<name> 3016e52347bdSJani Nikula Note that mem_start is often overloaded to mean 3017e52347bdSJani Nikula something different and driver-specific. 3018e52347bdSJani Nikula This usage is only documented in each driver source 3019e52347bdSJani Nikula file if at all. 3020e52347bdSJani Nikula 3021e52347bdSJani Nikula nf_conntrack.acct= 3022e52347bdSJani Nikula [NETFILTER] Enable connection tracking flow accounting 3023e52347bdSJani Nikula 0 to disable accounting 3024e52347bdSJani Nikula 1 to enable accounting 3025e52347bdSJani Nikula Default value is 0. 3026e52347bdSJani Nikula 3027e52347bdSJani Nikula nfsaddrs= [NFS] Deprecated. Use ip= instead. 30283eb30c51SNiklas Söderlund See Documentation/admin-guide/nfs/nfsroot.rst. 3029e52347bdSJani Nikula 3030e52347bdSJani Nikula nfsroot= [NFS] nfs root filesystem for disk-less boxes. 30313eb30c51SNiklas Söderlund See Documentation/admin-guide/nfs/nfsroot.rst. 3032e52347bdSJani Nikula 3033e52347bdSJani Nikula nfsrootdebug [NFS] enable nfsroot debugging messages. 30343eb30c51SNiklas Söderlund See Documentation/admin-guide/nfs/nfsroot.rst. 3035e52347bdSJani Nikula 3036e52347bdSJani Nikula nfs.callback_nr_threads= 3037e52347bdSJani Nikula [NFSv4] set the total number of threads that the 3038e52347bdSJani Nikula NFS client will assign to service NFSv4 callback 3039e52347bdSJani Nikula requests. 3040e52347bdSJani Nikula 3041e52347bdSJani Nikula nfs.callback_tcpport= 3042e52347bdSJani Nikula [NFS] set the TCP port on which the NFSv4 callback 3043e52347bdSJani Nikula channel should listen. 3044e52347bdSJani Nikula 3045e52347bdSJani Nikula nfs.cache_getent= 3046e52347bdSJani Nikula [NFS] sets the pathname to the program which is used 3047e52347bdSJani Nikula to update the NFS client cache entries. 3048e52347bdSJani Nikula 3049e52347bdSJani Nikula nfs.cache_getent_timeout= 3050e52347bdSJani Nikula [NFS] sets the timeout after which an attempt to 3051e52347bdSJani Nikula update a cache entry is deemed to have failed. 3052e52347bdSJani Nikula 3053e52347bdSJani Nikula nfs.idmap_cache_timeout= 3054e52347bdSJani Nikula [NFS] set the maximum lifetime for idmapper cache 3055e52347bdSJani Nikula entries. 3056e52347bdSJani Nikula 3057e52347bdSJani Nikula nfs.enable_ino64= 3058e52347bdSJani Nikula [NFS] enable 64-bit inode numbers. 3059e52347bdSJani Nikula If zero, the NFS client will fake up a 32-bit inode 3060e52347bdSJani Nikula number for the readdir() and stat() syscalls instead 3061e52347bdSJani Nikula of returning the full 64-bit number. 3062e52347bdSJani Nikula The default is to return 64-bit inode numbers. 3063e52347bdSJani Nikula 3064e52347bdSJani Nikula nfs.max_session_cb_slots= 3065e52347bdSJani Nikula [NFSv4.1] Sets the maximum number of session 3066e52347bdSJani Nikula slots the client will assign to the callback 3067e52347bdSJani Nikula channel. This determines the maximum number of 3068e52347bdSJani Nikula callbacks the client will process in parallel for 3069e52347bdSJani Nikula a particular server. 3070e52347bdSJani Nikula 3071e52347bdSJani Nikula nfs.max_session_slots= 3072e52347bdSJani Nikula [NFSv4.1] Sets the maximum number of session slots 3073e52347bdSJani Nikula the client will attempt to negotiate with the server. 3074e52347bdSJani Nikula This limits the number of simultaneous RPC requests 3075e52347bdSJani Nikula that the client can send to the NFSv4.1 server. 3076e52347bdSJani Nikula Note that there is little point in setting this 3077e52347bdSJani Nikula value higher than the max_tcp_slot_table_limit. 3078e52347bdSJani Nikula 3079e52347bdSJani Nikula nfs.nfs4_disable_idmapping= 3080e52347bdSJani Nikula [NFSv4] When set to the default of '1', this option 3081e52347bdSJani Nikula ensures that both the RPC level authentication 3082e52347bdSJani Nikula scheme and the NFS level operations agree to use 3083e52347bdSJani Nikula numeric uids/gids if the mount is using the 3084e52347bdSJani Nikula 'sec=sys' security flavour. In effect it is 3085e52347bdSJani Nikula disabling idmapping, which can make migration from 3086e52347bdSJani Nikula legacy NFSv2/v3 systems to NFSv4 easier. 3087e52347bdSJani Nikula Servers that do not support this mode of operation 3088e52347bdSJani Nikula will be autodetected by the client, and it will fall 3089e52347bdSJani Nikula back to using the idmapper. 3090e52347bdSJani Nikula To turn off this behaviour, set the value to '0'. 3091e52347bdSJani Nikula nfs.nfs4_unique_id= 3092e52347bdSJani Nikula [NFS4] Specify an additional fixed unique ident- 3093e52347bdSJani Nikula ification string that NFSv4 clients can insert into 3094e52347bdSJani Nikula their nfs_client_id4 string. This is typically a 3095e52347bdSJani Nikula UUID that is generated at system install time. 3096e52347bdSJani Nikula 3097e52347bdSJani Nikula nfs.send_implementation_id = 3098e52347bdSJani Nikula [NFSv4.1] Send client implementation identification 3099e52347bdSJani Nikula information in exchange_id requests. 3100e52347bdSJani Nikula If zero, no implementation identification information 3101e52347bdSJani Nikula will be sent. 3102e52347bdSJani Nikula The default is to send the implementation identification 3103e52347bdSJani Nikula information. 3104e52347bdSJani Nikula 3105e52347bdSJani Nikula nfs.recover_lost_locks = 3106e52347bdSJani Nikula [NFSv4] Attempt to recover locks that were lost due 3107e52347bdSJani Nikula to a lease timeout on the server. Please note that 3108e52347bdSJani Nikula doing this risks data corruption, since there are 3109e52347bdSJani Nikula no guarantees that the file will remain unchanged 3110e52347bdSJani Nikula after the locks are lost. 3111e52347bdSJani Nikula If you want to enable the kernel legacy behaviour of 3112e52347bdSJani Nikula attempting to recover these locks, then set this 3113e52347bdSJani Nikula parameter to '1'. 3114e52347bdSJani Nikula The default parameter value of '0' causes the kernel 3115e52347bdSJani Nikula not to attempt recovery of lost locks. 3116e52347bdSJani Nikula 3117e52347bdSJani Nikula nfs4.layoutstats_timer = 3118e52347bdSJani Nikula [NFSv4.2] Change the rate at which the kernel sends 3119e52347bdSJani Nikula layoutstats to the pNFS metadata server. 3120e52347bdSJani Nikula 3121e52347bdSJani Nikula Setting this to value to 0 causes the kernel to use 3122e52347bdSJani Nikula whatever value is the default set by the layout 3123e52347bdSJani Nikula driver. A non-zero value sets the minimum interval 3124e52347bdSJani Nikula in seconds between layoutstats transmissions. 3125e52347bdSJani Nikula 3126e52347bdSJani Nikula nfsd.nfs4_disable_idmapping= 3127e52347bdSJani Nikula [NFSv4] When set to the default of '1', the NFSv4 3128e52347bdSJani Nikula server will return only numeric uids and gids to 3129e52347bdSJani Nikula clients using auth_sys, and will accept numeric uids 3130e52347bdSJani Nikula and gids from such clients. This is intended to ease 3131e52347bdSJani Nikula migration from NFSv2/v3. 3132e52347bdSJani Nikula 3133160c7ba3SPaul E. McKenney nmi_backtrace.backtrace_idle [KNL] 3134160c7ba3SPaul E. McKenney Dump stacks even of idle CPUs in response to an 3135160c7ba3SPaul E. McKenney NMI stack-backtrace request. 3136160c7ba3SPaul E. McKenney 3137c0c74acbSHans-Christian Noren Egtvedt nmi_debug= [KNL,SH] Specify one or more actions to take 3138e52347bdSJani Nikula when a NMI is triggered. 3139e52347bdSJani Nikula Format: [state][,regs][,debounce][,die] 3140e52347bdSJani Nikula 3141e52347bdSJani Nikula nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels 3142e52347bdSJani Nikula Format: [panic,][nopanic,][num] 3143e52347bdSJani Nikula Valid num: 0 or 1 3144e52347bdSJani Nikula 0 - turn hardlockup detector in nmi_watchdog off 3145e52347bdSJani Nikula 1 - turn hardlockup detector in nmi_watchdog on 3146e52347bdSJani Nikula When panic is specified, panic when an NMI watchdog 314793285c01SZhenzhong Duan timeout occurs (or 'nopanic' to not panic on an NMI 314893285c01SZhenzhong Duan watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set) 314993285c01SZhenzhong Duan To disable both hard and soft lockup detectors, 3150e52347bdSJani Nikula please see 'nowatchdog'. 3151e52347bdSJani Nikula This is useful when you use a panic=... timeout and 3152e52347bdSJani Nikula need the box quickly up again. 3153e52347bdSJani Nikula 3154d22881dcSScott Wood These settings can be accessed at runtime via 3155d22881dcSScott Wood the nmi_watchdog and hardlockup_panic sysctls. 3156d22881dcSScott Wood 3157e52347bdSJani Nikula netpoll.carrier_timeout= 3158e52347bdSJani Nikula [NET] Specifies amount of time (in seconds) that 3159e52347bdSJani Nikula netpoll should wait for a carrier. By default netpoll 3160e52347bdSJani Nikula waits 4 seconds. 3161e52347bdSJani Nikula 3162e52347bdSJani Nikula no387 [BUGS=X86-32] Tells the kernel to use the 387 maths 3163e52347bdSJani Nikula emulation library even if a 387 maths coprocessor 3164e52347bdSJani Nikula is present. 3165e52347bdSJani Nikula 3166372fddf7SKirill A. Shutemov no5lvl [X86-64] Disable 5-level paging mode. Forces 3167372fddf7SKirill A. Shutemov kernel to use 4-level paging instead. 3168372fddf7SKirill A. Shutemov 3169b745cfbaSAndy Lutomirski nofsgsbase [X86] Disables FSGSBASE instructions. 3170dd649bd0SAndy Lutomirski 3171e52347bdSJani Nikula no_console_suspend 3172e52347bdSJani Nikula [HW] Never suspend the console 3173e52347bdSJani Nikula Disable suspending of consoles during suspend and 3174e52347bdSJani Nikula hibernate operations. Once disabled, debugging 3175e52347bdSJani Nikula messages can reach various consoles while the rest 3176e52347bdSJani Nikula of the system is being put to sleep (ie, while 3177e52347bdSJani Nikula debugging driver suspend/resume hooks). This may 3178e52347bdSJani Nikula not work reliably with all consoles, but is known 3179e52347bdSJani Nikula to work with serial and VGA consoles. 3180e52347bdSJani Nikula To facilitate more flexible debugging, we also add 3181e52347bdSJani Nikula console_suspend, a printk module parameter to control 3182e52347bdSJani Nikula it. Users could use console_suspend (usually 3183e52347bdSJani Nikula /sys/module/printk/parameters/console_suspend) to 3184e52347bdSJani Nikula turn on/off it dynamically. 3185e52347bdSJani Nikula 3186c6c40533SKairui Song novmcoredd [KNL,KDUMP] 3187c6c40533SKairui Song Disable device dump. Device dump allows drivers to 3188c6c40533SKairui Song append dump data to vmcore so you can collect driver 3189c6c40533SKairui Song specified debug info. Drivers can append the data 3190c6c40533SKairui Song without any limit and this data is stored in memory, 3191c6c40533SKairui Song so this may cause significant memory stress. Disabling 3192c6c40533SKairui Song device dump can help save memory but the driver debug 3193c6c40533SKairui Song data will be no longer available. This parameter 3194c6c40533SKairui Song is only available when CONFIG_PROC_VMCORE_DEVICE_DUMP 3195c6c40533SKairui Song is set. 3196c6c40533SKairui Song 3197e52347bdSJani Nikula noaliencache [MM, NUMA, SLAB] Disables the allocation of alien 3198e52347bdSJani Nikula caches in the slab allocator. Saves per-node memory, 3199e52347bdSJani Nikula but will impact performance. 3200e52347bdSJani Nikula 3201e52347bdSJani Nikula noalign [KNL,ARM] 3202e52347bdSJani Nikula 3203686140a1SVasily Gorbik noaltinstr [S390] Disables alternative instructions patching 3204686140a1SVasily Gorbik (CPU alternatives feature). 3205686140a1SVasily Gorbik 3206e52347bdSJani Nikula noapic [SMP,APIC] Tells the kernel to not make use of any 3207e52347bdSJani Nikula IOAPICs that may be present in the system. 3208e52347bdSJani Nikula 3209e52347bdSJani Nikula noautogroup Disable scheduler automatic task group creation. 3210e52347bdSJani Nikula 3211e52347bdSJani Nikula nobats [PPC] Do not use BATs for mapping kernel lowmem 3212e52347bdSJani Nikula on "Classic" PPC cores. 3213e52347bdSJani Nikula 3214e52347bdSJani Nikula nocache [ARM] 3215e52347bdSJani Nikula 3216e52347bdSJani Nikula noclflush [BUGS=X86] Don't use the CLFLUSH instruction 3217e52347bdSJani Nikula 3218e52347bdSJani Nikula nodelayacct [KNL] Disable per-task delay accounting 3219e52347bdSJani Nikula 3220e52347bdSJani Nikula nodsp [SH] Disable hardware DSP at boot time. 3221e52347bdSJani Nikula 3222e52347bdSJani Nikula noefi Disable EFI runtime services support. 3223e52347bdSJani Nikula 3224f7964378SNicholas Piggin no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel. 3225f7964378SNicholas Piggin 3226e52347bdSJani Nikula noexec [IA-64] 3227e52347bdSJani Nikula 3228e52347bdSJani Nikula noexec [X86] 3229e52347bdSJani Nikula On X86-32 available only on PAE configured kernels. 3230e52347bdSJani Nikula noexec=on: enable non-executable mappings (default) 3231e52347bdSJani Nikula noexec=off: disable non-executable mappings 3232e52347bdSJani Nikula 3233de78a9c4SChristophe Leroy nosmap [X86,PPC] 3234e52347bdSJani Nikula Disable SMAP (Supervisor Mode Access Prevention) 3235e52347bdSJani Nikula even if it is supported by processor. 3236e52347bdSJani Nikula 32370fb1c25aSChristophe Leroy nosmep [X86,PPC] 3238e52347bdSJani Nikula Disable SMEP (Supervisor Mode Execution Prevention) 3239e52347bdSJani Nikula even if it is supported by processor. 3240e52347bdSJani Nikula 3241e52347bdSJani Nikula noexec32 [X86-64] 3242e52347bdSJani Nikula This affects only 32-bit executables. 3243e52347bdSJani Nikula noexec32=on: enable non-executable mappings (default) 3244e52347bdSJani Nikula read doesn't imply executable mappings 3245e52347bdSJani Nikula noexec32=off: disable non-executable mappings 3246e52347bdSJani Nikula read implies executable mappings 3247e52347bdSJani Nikula 3248e52347bdSJani Nikula nofpu [MIPS,SH] Disable hardware FPU at boot time. 3249e52347bdSJani Nikula 3250e52347bdSJani Nikula nofxsr [BUGS=X86-32] Disables x86 floating point extended 3251e52347bdSJani Nikula register save and restore. The kernel will only save 3252e52347bdSJani Nikula legacy floating-point registers on task switch. 3253e52347bdSJani Nikula 32545b280ed4STian Tao nohugeiomap [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings. 3255e52347bdSJani Nikula 3256e52347bdSJani Nikula nosmt [KNL,S390] Disable symmetric multithreading (SMT). 3257e52347bdSJani Nikula Equivalent to smt=1. 3258e52347bdSJani Nikula 3259be3a5b0eSRandy Dunlap [KNL,X86] Disable symmetric multithreading (SMT). 3260506a66f3SThomas Gleixner nosmt=force: Force disable SMT, cannot be undone 3261506a66f3SThomas Gleixner via the sysfs control file. 326205736e4aSThomas Gleixner 3263a2059825SJosh Poimboeuf nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1 3264a2059825SJosh Poimboeuf (bounds check bypass). With this option data leaks are 3265a2059825SJosh Poimboeuf possible in the system. 326626cb1f36SDiana Craciun 3267e5ce5e72SJeremy Linton nospectre_v2 [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for 3268e5ce5e72SJeremy Linton the Spectre variant 2 (indirect branch prediction) 3269e5ce5e72SJeremy Linton vulnerability. System may allow data leaks with this 3270e5ce5e72SJeremy Linton option. 3271da285121SDavid Woodhouse 327224f7fc83SKonrad Rzeszutek Wilk nospec_store_bypass_disable 327324f7fc83SKonrad Rzeszutek Wilk [HW] Disable all mitigations for the Speculative Store Bypass vulnerability 327424f7fc83SKonrad Rzeszutek Wilk 32759a32a7e7SNicholas Piggin no_uaccess_flush 32769a32a7e7SNicholas Piggin [PPC] Don't flush the L1-D cache after accessing user data. 32779a32a7e7SNicholas Piggin 3278e52347bdSJani Nikula noxsave [BUGS=X86] Disables x86 extended register state save 3279e52347bdSJani Nikula and restore using xsave. The kernel will fallback to 3280e52347bdSJani Nikula enabling legacy floating-point and sse state. 3281e52347bdSJani Nikula 3282e52347bdSJani Nikula noxsaveopt [X86] Disables xsaveopt used in saving x86 extended 3283e52347bdSJani Nikula register states. The kernel will fall back to use 3284e52347bdSJani Nikula xsave to save the states. By using this parameter, 3285e52347bdSJani Nikula performance of saving the states is degraded because 3286e52347bdSJani Nikula xsave doesn't support modified optimization while 3287e52347bdSJani Nikula xsaveopt supports it on xsaveopt enabled systems. 3288e52347bdSJani Nikula 3289e52347bdSJani Nikula noxsaves [X86] Disables xsaves and xrstors used in saving and 3290e52347bdSJani Nikula restoring x86 extended register state in compacted 3291e52347bdSJani Nikula form of xsave area. The kernel will fall back to use 3292e52347bdSJani Nikula xsaveopt and xrstor to save and restore the states 3293e52347bdSJani Nikula in standard form of xsave area. By using this 3294e52347bdSJani Nikula parameter, xsave area per process might occupy more 3295e52347bdSJani Nikula memory on xsaves enabled systems. 3296e52347bdSJani Nikula 32973cae85f5SFlorian Fainelli nohlt [ARM,ARM64,MICROBLAZE,SH] Forces the kernel to busy wait 32983cae85f5SFlorian Fainelli in do_idle() and not use the arch_cpu_idle() 32993cae85f5SFlorian Fainelli implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP 33003cae85f5SFlorian Fainelli to be effective. This is useful on platforms where the 33013cae85f5SFlorian Fainelli sleep(SH) or wfi(ARM,ARM64) instructions do not work 33023cae85f5SFlorian Fainelli correctly or when doing power measurements to evalute 33033cae85f5SFlorian Fainelli the impact of the sleep instructions. This is also 33043cae85f5SFlorian Fainelli useful when using JTAG debugger. 3305e52347bdSJani Nikula 3306e52347bdSJani Nikula no_file_caps Tells the kernel not to honor file capabilities. The 3307e52347bdSJani Nikula only way then for a file to be executed with privilege 3308e52347bdSJani Nikula is to be setuid root or executed by root. 3309e52347bdSJani Nikula 3310e52347bdSJani Nikula nohalt [IA-64] Tells the kernel not to use the power saving 3311e52347bdSJani Nikula function PAL_HALT_LIGHT when idle. This increases 3312e52347bdSJani Nikula power-consumption. On the positive side, it reduces 3313e52347bdSJani Nikula interrupt wake-up latency, which may improve performance 3314e52347bdSJani Nikula in certain environments such as networked servers or 3315e52347bdSJani Nikula real-time systems. 3316e52347bdSJani Nikula 33175ead723aSTimur Tabi no_hash_pointers 33185ead723aSTimur Tabi Force pointers printed to the console or buffers to be 33195ead723aSTimur Tabi unhashed. By default, when a pointer is printed via %p 33205ead723aSTimur Tabi format string, that pointer is "hashed", i.e. obscured 33215ead723aSTimur Tabi by hashing the pointer value. This is a security feature 33225ead723aSTimur Tabi that hides actual kernel addresses from unprivileged 33235ead723aSTimur Tabi users, but it also makes debugging the kernel more 33245ead723aSTimur Tabi difficult since unequal pointers can no longer be 33255ead723aSTimur Tabi compared. However, if this command-line option is 33265ead723aSTimur Tabi specified, then all normal pointers will have their true 33275ead723aSTimur Tabi value printed. Pointers printed via %pK may still be 33285ead723aSTimur Tabi hashed. This option should only be specified when 33295ead723aSTimur Tabi debugging the kernel. Please do not use on production 33305ead723aSTimur Tabi kernels. 33315ead723aSTimur Tabi 3332e52347bdSJani Nikula nohibernate [HIBERNATION] Disable hibernation and resume. 3333e52347bdSJani Nikula 3334e52347bdSJani Nikula nohz= [KNL] Boottime enable/disable dynamic ticks 3335e52347bdSJani Nikula Valid arguments: on, off 3336e52347bdSJani Nikula Default: on 3337e52347bdSJani Nikula 3338d94d1053SFrederic Weisbecker nohz_full= [KNL,BOOT,SMP,ISOL] 3339e52347bdSJani Nikula The argument is a cpu list, as described above. 3340e52347bdSJani Nikula In kernels built with CONFIG_NO_HZ_FULL=y, set 3341e52347bdSJani Nikula the specified list of CPUs whose tick will be stopped 3342e52347bdSJani Nikula whenever possible. The boot CPU will be forced outside 3343f99bcb2cSPaul E. McKenney the range to maintain the timekeeping. Any CPUs 3344f99bcb2cSPaul E. McKenney in this list will have their RCU callbacks offloaded, 3345f99bcb2cSPaul E. McKenney just as if they had also been called out in the 3346f99bcb2cSPaul E. McKenney rcu_nocbs= boot parameter. 3347e52347bdSJani Nikula 3348e52347bdSJani Nikula noiotrap [SH] Disables trapped I/O port accesses. 3349e52347bdSJani Nikula 3350e52347bdSJani Nikula noirqdebug [X86-32] Disables the code which attempts to detect and 3351e52347bdSJani Nikula disable unhandled interrupt sources. 3352e52347bdSJani Nikula 3353e52347bdSJani Nikula no_timer_check [X86,APIC] Disables the code which tests for 3354e52347bdSJani Nikula broken timer IRQ sources. 3355e52347bdSJani Nikula 3356e52347bdSJani Nikula noisapnp [ISAPNP] Disables ISA PnP code. 3357e52347bdSJani Nikula 3358e52347bdSJani Nikula noinitrd [RAM] Tells the kernel not to load any configured 3359e52347bdSJani Nikula initial RAM disk. 3360e52347bdSJani Nikula 3361e52347bdSJani Nikula nointremap [X86-64, Intel-IOMMU] Do not enable interrupt 3362e52347bdSJani Nikula remapping. 3363e52347bdSJani Nikula [Deprecated - use intremap=off] 3364e52347bdSJani Nikula 3365e52347bdSJani Nikula nointroute [IA-64] 3366e52347bdSJani Nikula 3367e52347bdSJani Nikula noinvpcid [X86] Disable the INVPCID cpu feature. 3368e52347bdSJani Nikula 3369e52347bdSJani Nikula nojitter [IA-64] Disables jitter checking for ITC timers. 3370e52347bdSJani Nikula 3371e52347bdSJani Nikula no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver 3372e52347bdSJani Nikula 3373e52347bdSJani Nikula no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page 3374e52347bdSJani Nikula fault handling. 3375e52347bdSJani Nikula 3376e7aa8c2eSLinus Torvalds no-vmw-sched-clock 3377e7aa8c2eSLinus Torvalds [X86,PV_OPS] Disable paravirtualized VMware scheduler 3378e7aa8c2eSLinus Torvalds clock and use the default one. 3379e7aa8c2eSLinus Torvalds 3380e73a8f38SAlexey Makhalov no-steal-acc [X86,PV_OPS,ARM64] Disable paravirtualized steal time 3381e0685fa2SSteven Price accounting. steal time is computed, but won't 3382e0685fa2SSteven Price influence scheduler behaviour 3383e52347bdSJani Nikula 3384e52347bdSJani Nikula nolapic [X86-32,APIC] Do not enable or use the local APIC. 3385e52347bdSJani Nikula 3386e52347bdSJani Nikula nolapic_timer [X86-32,APIC] Do not use the local APIC timer. 3387e52347bdSJani Nikula 3388e52347bdSJani Nikula noltlbs [PPC] Do not use large page/tlb entries for kernel 3389e52347bdSJani Nikula lowmem mapping on PPC40x and PPC8xx 3390e52347bdSJani Nikula 3391e52347bdSJani Nikula nomca [IA-64] Disable machine check abort handling 3392e52347bdSJani Nikula 3393e52347bdSJani Nikula nomce [X86-32] Disable Machine Check Exception 3394e52347bdSJani Nikula 3395e52347bdSJani Nikula nomfgpt [X86-32] Disable Multi-Function General Purpose 3396e52347bdSJani Nikula Timer usage (for AMD Geode machines). 3397e52347bdSJani Nikula 3398e52347bdSJani Nikula nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to 3399e52347bdSJani Nikula shutdown the other cpus. Instead use the REBOOT_VECTOR 3400e52347bdSJani Nikula irq. 3401e52347bdSJani Nikula 3402e52347bdSJani Nikula nomodule Disable module load 3403e52347bdSJani Nikula 3404e52347bdSJani Nikula nopat [X86] Disable PAT (page attribute table extension of 3405e52347bdSJani Nikula pagetables) support. 3406e52347bdSJani Nikula 34070790c9aaSAndy Lutomirski nopcid [X86-64] Disable the PCID cpu feature. 34080790c9aaSAndy Lutomirski 3409e52347bdSJani Nikula norandmaps Don't use address space randomization. Equivalent to 3410e52347bdSJani Nikula echo 0 > /proc/sys/kernel/randomize_va_space 3411e52347bdSJani Nikula 3412e52347bdSJani Nikula noreplace-smp [X86-32,SMP] Don't replace SMP instructions 3413e52347bdSJani Nikula with UP alternatives 3414e52347bdSJani Nikula 3415e52347bdSJani Nikula nordrand [X86] Disable kernel use of the RDRAND and 3416e52347bdSJani Nikula RDSEED instructions even if they are supported 3417e52347bdSJani Nikula by the processor. RDRAND and RDSEED are still 3418e52347bdSJani Nikula available to user space applications. 3419e52347bdSJani Nikula 3420e52347bdSJani Nikula noresume [SWSUSP] Disables resume and restores original swap 3421e52347bdSJani Nikula space. 3422e52347bdSJani Nikula 3423e52347bdSJani Nikula no-scroll [VGA] Disables scrollback. 3424e52347bdSJani Nikula This is required for the Braillex ib80-piezo Braille 3425e52347bdSJani Nikula reader made by F.H. Papenmeier (Germany). 3426e52347bdSJani Nikula 3427e52347bdSJani Nikula nosbagart [IA-64] 3428e52347bdSJani Nikula 3429e52347bdSJani Nikula nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. 3430e52347bdSJani Nikula 343138853a30SJarkko Sakkinen nosgx [X86-64,SGX] Disables Intel SGX kernel support. 343238853a30SJarkko Sakkinen 3433e52347bdSJani Nikula nosmp [SMP] Tells an SMP kernel to act as a UP kernel, 3434e52347bdSJani Nikula and disable the IO APIC. legacy for "maxcpus=0". 3435e52347bdSJani Nikula 3436e52347bdSJani Nikula nosoftlockup [KNL] Disable the soft-lockup detector. 3437e52347bdSJani Nikula 3438e52347bdSJani Nikula nosync [HW,M68K] Disables sync negotiation for all devices. 3439e52347bdSJani Nikula 3440e52347bdSJani Nikula nowatchdog [KNL] Disable both lockup detectors, i.e. 3441e52347bdSJani Nikula soft-lockup and NMI watchdog (hard-lockup). 3442e52347bdSJani Nikula 3443e52347bdSJani Nikula nowb [ARM] 3444e52347bdSJani Nikula 3445e52347bdSJani Nikula nox2apic [X86-64,APIC] Do not enable x2APIC mode. 3446e52347bdSJani Nikula 3447e52347bdSJani Nikula cpu0_hotplug [X86] Turn on CPU0 hotplug feature when 3448e52347bdSJani Nikula CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. 3449e52347bdSJani Nikula Some features depend on CPU0. Known dependencies are: 3450e52347bdSJani Nikula 1. Resume from suspend/hibernate depends on CPU0. 3451e52347bdSJani Nikula Suspend/hibernate will fail if CPU0 is offline and you 3452e52347bdSJani Nikula need to online CPU0 before suspend/hibernate. 3453e52347bdSJani Nikula 2. PIC interrupts also depend on CPU0. CPU0 can't be 3454e52347bdSJani Nikula removed if a PIC interrupt is detected. 3455e52347bdSJani Nikula It's said poweroff/reboot may depend on CPU0 on some 3456e52347bdSJani Nikula machines although I haven't seen such issues so far 3457e52347bdSJani Nikula after CPU0 is offline on a few tested machines. 3458e52347bdSJani Nikula If the dependencies are under your control, you can 3459e52347bdSJani Nikula turn on cpu0_hotplug. 3460e52347bdSJani Nikula 346135b55ef2SNoam Camus nps_mtm_hs_ctr= [KNL,ARC] 346235b55ef2SNoam Camus This parameter sets the maximum duration, in 346335b55ef2SNoam Camus cycles, each HW thread of the CTOP can run 346435b55ef2SNoam Camus without interruptions, before HW switches it. 346535b55ef2SNoam Camus The actual maximum duration is 16 times this 346635b55ef2SNoam Camus parameter's value. 346735b55ef2SNoam Camus Format: integer between 1 and 255 346835b55ef2SNoam Camus Default: 255 346935b55ef2SNoam Camus 3470e52347bdSJani Nikula nptcg= [IA-64] Override max number of concurrent global TLB 3471e52347bdSJani Nikula purges which is reported from either PAL_VM_SUMMARY or 3472e52347bdSJani Nikula SAL PALO. 3473e52347bdSJani Nikula 3474e52347bdSJani Nikula nr_cpus= [SMP] Maximum number of processors that an SMP kernel 3475e52347bdSJani Nikula could support. nr_cpus=n : n >= 1 limits the kernel to 3476e52347bdSJani Nikula support 'n' processors. It could be larger than the 3477e52347bdSJani Nikula number of already plugged CPU during bootup, later in 3478e52347bdSJani Nikula runtime you can physically add extra cpu until it reaches 3479e52347bdSJani Nikula n. So during boot up some boot time memory for per-cpu 3480e52347bdSJani Nikula variables need be pre-allocated for later physical cpu 3481e52347bdSJani Nikula hot plugging. 3482e52347bdSJani Nikula 3483e52347bdSJani Nikula nr_uarts= [SERIAL] maximum number of UARTs to be registered. 3484e52347bdSJani Nikula 3485e52347bdSJani Nikula numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing. 3486e52347bdSJani Nikula Allowed values are enable and disable 3487e52347bdSJani Nikula 3488e52347bdSJani Nikula numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. 3489c9bff3eeSMichal Hocko 'node', 'default' can be specified 3490e52347bdSJani Nikula This can be set from sysctl after boot. 349157043247SMauro Carvalho Chehab See Documentation/admin-guide/sysctl/vm.rst for details. 3492e52347bdSJani Nikula 3493e52347bdSJani Nikula ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. 3494a74e2a22SMauro Carvalho Chehab See Documentation/core-api/debugging-via-ohci1394.rst for more 3495e52347bdSJani Nikula info. 3496e52347bdSJani Nikula 3497e52347bdSJani Nikula olpc_ec_timeout= [OLPC] ms delay when issuing EC commands 3498e52347bdSJani Nikula Rather than timing out after 20 ms if an EC 3499e52347bdSJani Nikula command is not properly ACKed, override the length 3500e52347bdSJani Nikula of the timeout. We have interrupts disabled while 3501e52347bdSJani Nikula waiting for the ACK, so if this is set too high 3502e52347bdSJani Nikula interrupts *may* be lost! 3503e52347bdSJani Nikula 3504e52347bdSJani Nikula omap_mux= [OMAP] Override bootloader pin multiplexing. 3505e52347bdSJani Nikula Format: <mux_mode0.mode_name=value>... 3506e52347bdSJani Nikula For example, to override I2C bus2: 3507e52347bdSJani Nikula omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 3508e52347bdSJani Nikula 3509e52347bdSJani Nikula oops=panic Always panic on oopses. Default is to just kill the 3510e52347bdSJani Nikula process, but there is a small probability of 3511e52347bdSJani Nikula deadlocking the machine. 3512e52347bdSJani Nikula This will also cause panics on machine check exceptions. 3513e52347bdSJani Nikula Useful together with panic=30 to trigger a reboot. 3514e52347bdSJani Nikula 3515e900a918SDan Williams page_alloc.shuffle= 3516e900a918SDan Williams [KNL] Boolean flag to control whether the page allocator 3517e900a918SDan Williams should randomize its free lists. The randomization may 3518e900a918SDan Williams be automatically enabled if the kernel detects it is 3519e900a918SDan Williams running on a platform with a direct-mapped memory-side 3520e900a918SDan Williams cache, and this parameter can be used to 3521e900a918SDan Williams override/disable that behavior. The state of the flag 3522e900a918SDan Williams can be read from sysfs at: 3523e900a918SDan Williams /sys/module/page_alloc/parameters/shuffle. 3524e900a918SDan Williams 3525e52347bdSJani Nikula page_owner= [KNL] Boot-time page_owner enabling option. 3526e52347bdSJani Nikula Storage of the information about who allocated 3527e52347bdSJani Nikula each page is disabled in default. With this switch, 3528e52347bdSJani Nikula we can turn it on. 3529e52347bdSJani Nikula on: enable the feature 3530e52347bdSJani Nikula 3531e52347bdSJani Nikula page_poison= [KNL] Boot-time parameter changing the state of 35328c9a134cSKees Cook poisoning on the buddy allocator, available with 35338c9a134cSKees Cook CONFIG_PAGE_POISONING=y. 35348c9a134cSKees Cook off: turn off poisoning (default) 3535e52347bdSJani Nikula on: turn on poisoning 3536e52347bdSJani Nikula 3537e52347bdSJani Nikula panic= [KNL] Kernel behaviour on panic: delay <timeout> 3538e52347bdSJani Nikula timeout > 0: seconds before rebooting 3539e52347bdSJani Nikula timeout = 0: wait forever 3540e52347bdSJani Nikula timeout < 0: reboot immediately 3541e52347bdSJani Nikula Format: <timeout> 3542e52347bdSJani Nikula 3543d999bd93SFeng Tang panic_print= Bitmask for printing system info when panic happens. 3544d999bd93SFeng Tang User can chose combination of the following bits: 3545d999bd93SFeng Tang bit 0: print all tasks info 3546d999bd93SFeng Tang bit 1: print system memory info 3547d999bd93SFeng Tang bit 2: print timer info 3548d999bd93SFeng Tang bit 3: print locks info if CONFIG_LOCKDEP is on 3549d999bd93SFeng Tang bit 4: print ftrace buffer 3550de6da1e8SFeng Tang bit 5: print all printk messages in buffer 3551d999bd93SFeng Tang 3552db38d5c1SRafael Aquini panic_on_taint= Bitmask for conditionally calling panic() in add_taint() 3553db38d5c1SRafael Aquini Format: <hex>[,nousertaint] 3554db38d5c1SRafael Aquini Hexadecimal bitmask representing the set of TAINT flags 3555db38d5c1SRafael Aquini that will cause the kernel to panic when add_taint() is 3556db38d5c1SRafael Aquini called with any of the flags in this set. 3557db38d5c1SRafael Aquini The optional switch "nousertaint" can be utilized to 3558db38d5c1SRafael Aquini prevent userspace forced crashes by writing to sysctl 3559db38d5c1SRafael Aquini /proc/sys/kernel/tainted any flagset matching with the 3560db38d5c1SRafael Aquini bitmask set on panic_on_taint. 3561db38d5c1SRafael Aquini See Documentation/admin-guide/tainted-kernels.rst for 3562db38d5c1SRafael Aquini extra details on the taint flags that users can pick 3563db38d5c1SRafael Aquini to compose the bitmask to assign to panic_on_taint. 3564db38d5c1SRafael Aquini 3565e52347bdSJani Nikula panic_on_warn panic() instead of WARN(). Useful to cause kdump 3566e52347bdSJani Nikula on a WARN(). 3567e52347bdSJani Nikula 3568e52347bdSJani Nikula crash_kexec_post_notifiers 3569e52347bdSJani Nikula Run kdump after running panic-notifiers and dumping 3570e52347bdSJani Nikula kmsg. This only for the users who doubt kdump always 3571e52347bdSJani Nikula succeeds in any situation. 3572e52347bdSJani Nikula Note that this also increases risks of kdump failure, 3573e52347bdSJani Nikula because some panic notifiers can make the crashed 3574e52347bdSJani Nikula kernel more unstable. 3575e52347bdSJani Nikula 3576e52347bdSJani Nikula parkbd.port= [HW] Parallel port number the keyboard adapter is 3577e52347bdSJani Nikula connected to, default is 0. 3578e52347bdSJani Nikula Format: <parport#> 3579e52347bdSJani Nikula parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, 3580e52347bdSJani Nikula 0 for XT, 1 for AT (default is AT). 3581e52347bdSJani Nikula Format: <mode> 3582e52347bdSJani Nikula 3583e52347bdSJani Nikula parport= [HW,PPT] Specify parallel ports. 0 disables. 3584e52347bdSJani Nikula Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } 3585e52347bdSJani Nikula Use 'auto' to force the driver to use any 3586e52347bdSJani Nikula IRQ/DMA settings detected (the default is to 3587e52347bdSJani Nikula ignore detected IRQ/DMA settings because of 3588e52347bdSJani Nikula possible conflicts). You can specify the base 3589e52347bdSJani Nikula address, IRQ, and DMA settings; IRQ and DMA 3590e52347bdSJani Nikula should be numbers, or 'auto' (for using detected 3591e52347bdSJani Nikula settings on that particular port), or 'nofifo' 3592e52347bdSJani Nikula (to avoid using a FIFO even if it is detected). 3593e52347bdSJani Nikula Parallel ports are assigned in the order they 3594e52347bdSJani Nikula are specified on the command line, starting 3595e52347bdSJani Nikula with parport0. 3596e52347bdSJani Nikula 3597e52347bdSJani Nikula parport_init_mode= [HW,PPT] 3598e52347bdSJani Nikula Configure VIA parallel port to operate in 3599e52347bdSJani Nikula a specific mode. This is necessary on Pegasos 3600e52347bdSJani Nikula computer where firmware has no options for setting 3601e52347bdSJani Nikula up parallel port mode and sets it to spp. 3602e52347bdSJani Nikula Currently this function knows 686a and 8231 chips. 3603e52347bdSJani Nikula Format: [spp|ps2|epp|ecp|ecpepp] 3604e52347bdSJani Nikula 3605e52347bdSJani Nikula pause_on_oops= 3606e52347bdSJani Nikula Halt all CPUs after the first oops has been printed for 3607e52347bdSJani Nikula the specified number of seconds. This is to be used if 3608e52347bdSJani Nikula your oopses keep scrolling off the screen. 3609e52347bdSJani Nikula 3610e52347bdSJani Nikula pcbit= [HW,ISDN] 3611e52347bdSJani Nikula 3612e52347bdSJani Nikula pcd. [PARIDE] 3613e52347bdSJani Nikula See header of drivers/block/paride/pcd.c. 3614e7751617SMauro Carvalho Chehab See also Documentation/admin-guide/blockdev/paride.rst. 3615e52347bdSJani Nikula 361607d8d7e5SLogan Gunthorpe pci=option[,option...] [PCI] various PCI subsystem options. 361707d8d7e5SLogan Gunthorpe 361807d8d7e5SLogan Gunthorpe Some options herein operate on a specific device 361907d8d7e5SLogan Gunthorpe or a set of devices (<pci_dev>). These are 362007d8d7e5SLogan Gunthorpe specified in one of the following formats: 362107d8d7e5SLogan Gunthorpe 362245db3370SLogan Gunthorpe [<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]* 362307d8d7e5SLogan Gunthorpe pci:<vendor>:<device>[:<subvendor>:<subdevice>] 362407d8d7e5SLogan Gunthorpe 362507d8d7e5SLogan Gunthorpe Note: the first format specifies a PCI 362607d8d7e5SLogan Gunthorpe bus/device/function address which may change 362707d8d7e5SLogan Gunthorpe if new hardware is inserted, if motherboard 362807d8d7e5SLogan Gunthorpe firmware changes, or due to changes caused 362907d8d7e5SLogan Gunthorpe by other kernel parameters. If the 363007d8d7e5SLogan Gunthorpe domain is left unspecified, it is 363145db3370SLogan Gunthorpe taken to be zero. Optionally, a path 363245db3370SLogan Gunthorpe to a device through multiple device/function 363345db3370SLogan Gunthorpe addresses can be specified after the base 363445db3370SLogan Gunthorpe address (this is more robust against 363545db3370SLogan Gunthorpe renumbering issues). The second format 363607d8d7e5SLogan Gunthorpe selects devices using IDs from the 363707d8d7e5SLogan Gunthorpe configuration space which may match multiple 363807d8d7e5SLogan Gunthorpe devices in the system. 363907d8d7e5SLogan Gunthorpe 364011eb0e0eSSinan Kaya earlydump dump PCI config space before the kernel 3641e52347bdSJani Nikula changes anything 3642e52347bdSJani Nikula off [X86] don't probe for the PCI bus 3643e52347bdSJani Nikula bios [X86-32] force use of PCI BIOS, don't access 3644e52347bdSJani Nikula the hardware directly. Use this if your machine 3645e52347bdSJani Nikula has a non-standard PCI host bridge. 3646e52347bdSJani Nikula nobios [X86-32] disallow use of PCI BIOS, only direct 3647e52347bdSJani Nikula hardware access methods are allowed. Use this 3648e52347bdSJani Nikula if you experience crashes upon bootup and you 3649e52347bdSJani Nikula suspect they are caused by the BIOS. 3650e52347bdSJani Nikula conf1 [X86] Force use of PCI Configuration Access 3651e52347bdSJani Nikula Mechanism 1 (config address in IO port 0xCF8, 3652e52347bdSJani Nikula data in IO port 0xCFC, both 32-bit). 3653e52347bdSJani Nikula conf2 [X86] Force use of PCI Configuration Access 3654e52347bdSJani Nikula Mechanism 2 (IO port 0xCF8 is an 8-bit port for 3655e52347bdSJani Nikula the function, IO port 0xCFA, also 8-bit, sets 3656e52347bdSJani Nikula bus number. The config space is then accessed 3657e52347bdSJani Nikula through ports 0xC000-0xCFFF). 3658e52347bdSJani Nikula See http://wiki.osdev.org/PCI for more info 3659e52347bdSJani Nikula on the configuration access mechanisms. 3660e52347bdSJani Nikula noaer [PCIE] If the PCIEAER kernel config parameter is 3661e52347bdSJani Nikula enabled, this kernel boot option can be used to 3662e52347bdSJani Nikula disable the use of PCIE advanced error reporting. 3663e52347bdSJani Nikula nodomains [PCI] Disable support for multiple PCI 3664e52347bdSJani Nikula root domains (aka PCI segments, in ACPI-speak). 3665e52347bdSJani Nikula nommconf [X86] Disable use of MMCONFIG for PCI 3666e52347bdSJani Nikula Configuration 3667e52347bdSJani Nikula check_enable_amd_mmconf [X86] check for and enable 3668e52347bdSJani Nikula properly configured MMIO access to PCI 3669e52347bdSJani Nikula config space on AMD family 10h CPU 3670e52347bdSJani Nikula nomsi [MSI] If the PCI_MSI kernel config parameter is 3671e52347bdSJani Nikula enabled, this kernel boot option can be used to 3672e52347bdSJani Nikula disable the use of MSI interrupts system-wide. 3673e52347bdSJani Nikula noioapicquirk [APIC] Disable all boot interrupt quirks. 3674e52347bdSJani Nikula Safety option to keep boot IRQs enabled. This 3675e52347bdSJani Nikula should never be necessary. 3676e52347bdSJani Nikula ioapicreroute [APIC] Enable rerouting of boot IRQs to the 3677e52347bdSJani Nikula primary IO-APIC for bridges that cannot disable 3678e52347bdSJani Nikula boot IRQs. This fixes a source of spurious IRQs 3679e52347bdSJani Nikula when the system masks IRQs. 3680e52347bdSJani Nikula noioapicreroute [APIC] Disable workaround that uses the 3681e52347bdSJani Nikula boot IRQ equivalent of an IRQ that connects to 3682e52347bdSJani Nikula a chipset where boot IRQs cannot be disabled. 3683e52347bdSJani Nikula The opposite of ioapicreroute. 3684e52347bdSJani Nikula biosirq [X86-32] Use PCI BIOS calls to get the interrupt 3685e52347bdSJani Nikula routing table. These calls are known to be buggy 3686e52347bdSJani Nikula on several machines and they hang the machine 3687e52347bdSJani Nikula when used, but on other computers it's the only 3688e52347bdSJani Nikula way to get the interrupt routing table. Try 3689e52347bdSJani Nikula this option if the kernel is unable to allocate 3690e52347bdSJani Nikula IRQs or discover secondary PCI buses on your 3691e52347bdSJani Nikula motherboard. 3692e52347bdSJani Nikula rom [X86] Assign address space to expansion ROMs. 3693e52347bdSJani Nikula Use with caution as certain devices share 3694e52347bdSJani Nikula address decoders between ROMs and other 3695e52347bdSJani Nikula resources. 3696e52347bdSJani Nikula norom [X86] Do not assign address space to 3697e52347bdSJani Nikula expansion ROMs that do not already have 3698e52347bdSJani Nikula BIOS assigned address ranges. 3699e52347bdSJani Nikula nobar [X86] Do not assign address space to the 3700e52347bdSJani Nikula BARs that weren't assigned by the BIOS. 3701e52347bdSJani Nikula irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be 3702e52347bdSJani Nikula assigned automatically to PCI devices. You can 3703e52347bdSJani Nikula make the kernel exclude IRQs of your ISA cards 3704e52347bdSJani Nikula this way. 3705e52347bdSJani Nikula pirqaddr=0xAAAAA [X86] Specify the physical address 3706e52347bdSJani Nikula of the PIRQ table (normally generated 3707e52347bdSJani Nikula by the BIOS) if it is outside the 3708e52347bdSJani Nikula F0000h-100000h range. 3709e52347bdSJani Nikula lastbus=N [X86] Scan all buses thru bus #N. Can be 3710e52347bdSJani Nikula useful if the kernel is unable to find your 3711e52347bdSJani Nikula secondary buses and you want to tell it 3712e52347bdSJani Nikula explicitly which ones they are. 3713e52347bdSJani Nikula assign-busses [X86] Always assign all PCI bus 3714e52347bdSJani Nikula numbers ourselves, overriding 3715e52347bdSJani Nikula whatever the firmware may have done. 3716e52347bdSJani Nikula usepirqmask [X86] Honor the possible IRQ mask stored 3717e52347bdSJani Nikula in the BIOS $PIR table. This is needed on 3718e52347bdSJani Nikula some systems with broken BIOSes, notably 3719e52347bdSJani Nikula some HP Pavilion N5400 and Omnibook XE3 3720e52347bdSJani Nikula notebooks. This will have no effect if ACPI 3721e52347bdSJani Nikula IRQ routing is enabled. 3722e52347bdSJani Nikula noacpi [X86] Do not use ACPI for IRQ routing 3723e52347bdSJani Nikula or for PCI scanning. 3724e52347bdSJani Nikula use_crs [X86] Use PCI host bridge window information 3725e52347bdSJani Nikula from ACPI. On BIOSes from 2008 or later, this 3726e52347bdSJani Nikula is enabled by default. If you need to use this, 3727e52347bdSJani Nikula please report a bug. 3728e52347bdSJani Nikula nocrs [X86] Ignore PCI host bridge windows from ACPI. 3729e52347bdSJani Nikula If you need to use this, please report a bug. 3730e52347bdSJani Nikula routeirq Do IRQ routing for all PCI devices. 3731e52347bdSJani Nikula This is normally done in pci_enable_device(), 3732e52347bdSJani Nikula so this option is a temporary workaround 3733e52347bdSJani Nikula for broken drivers that don't call it. 3734e52347bdSJani Nikula skip_isa_align [X86] do not align io start addr, so can 3735e52347bdSJani Nikula handle more pci cards 3736e52347bdSJani Nikula noearly [X86] Don't do any early type 1 scanning. 3737e52347bdSJani Nikula This might help on some broken boards which 3738e52347bdSJani Nikula machine check when some devices' config space 3739e52347bdSJani Nikula is read. But various workarounds are disabled 3740e52347bdSJani Nikula and some IOMMU drivers will not work. 3741e52347bdSJani Nikula bfsort Sort PCI devices into breadth-first order. 3742e52347bdSJani Nikula This sorting is done to get a device 3743e52347bdSJani Nikula order compatible with older (<= 2.4) kernels. 3744e52347bdSJani Nikula nobfsort Don't sort PCI devices into breadth-first order. 3745e52347bdSJani Nikula pcie_bus_tune_off Disable PCIe MPS (Max Payload Size) 3746e52347bdSJani Nikula tuning and use the BIOS-configured MPS defaults. 3747e52347bdSJani Nikula pcie_bus_safe Set every device's MPS to the largest value 3748e52347bdSJani Nikula supported by all devices below the root complex. 3749e52347bdSJani Nikula pcie_bus_perf Set device MPS to the largest allowable MPS 3750e52347bdSJani Nikula based on its parent bus. Also set MRRS (Max 3751e52347bdSJani Nikula Read Request Size) to the largest supported 3752e52347bdSJani Nikula value (no larger than the MPS that the device 3753e52347bdSJani Nikula or bus can support) for best performance. 3754e52347bdSJani Nikula pcie_bus_peer2peer Set every device's MPS to 128B, which 3755e52347bdSJani Nikula every device is guaranteed to support. This 3756e52347bdSJani Nikula configuration allows peer-to-peer DMA between 3757e52347bdSJani Nikula any pair of devices, possibly at the cost of 3758e52347bdSJani Nikula reduced performance. This also guarantees 3759e52347bdSJani Nikula that hot-added devices will work. 3760e52347bdSJani Nikula cbiosize=nn[KMG] The fixed amount of bus space which is 3761e52347bdSJani Nikula reserved for the CardBus bridge's IO window. 3762e52347bdSJani Nikula The default value is 256 bytes. 3763e52347bdSJani Nikula cbmemsize=nn[KMG] The fixed amount of bus space which is 3764e52347bdSJani Nikula reserved for the CardBus bridge's memory 3765e52347bdSJani Nikula window. The default value is 64 megabytes. 3766e52347bdSJani Nikula resource_alignment= 3767e52347bdSJani Nikula Format: 376807d8d7e5SLogan Gunthorpe [<order of align>@]<pci_dev>[; ...] 3769e52347bdSJani Nikula Specifies alignment and device to reassign 377007d8d7e5SLogan Gunthorpe aligned memory resources. How to 377107d8d7e5SLogan Gunthorpe specify the device is described above. 3772e52347bdSJani Nikula If <order of align> is not specified, 3773e52347bdSJani Nikula PAGE_SIZE is used as alignment. 37743b1b1ce3SAlexey Kardashevskiy A PCI-PCI bridge can be specified if resource 3775e52347bdSJani Nikula windows need to be expanded. 3776e52347bdSJani Nikula To specify the alignment for several 3777e52347bdSJani Nikula instances of a device, the PCI vendor, 3778e52347bdSJani Nikula device, subvendor, and subdevice may be 37793b1b1ce3SAlexey Kardashevskiy specified, e.g., 12@pci:8086:9c22:103c:198f 37803b1b1ce3SAlexey Kardashevskiy for 4096-byte alignment. 3781e52347bdSJani Nikula ecrc= Enable/disable PCIe ECRC (transaction layer 3782e52347bdSJani Nikula end-to-end CRC checking). 3783e52347bdSJani Nikula bios: Use BIOS/firmware settings. This is the 3784e52347bdSJani Nikula the default. 3785e52347bdSJani Nikula off: Turn ECRC off 3786e52347bdSJani Nikula on: Turn ECRC on. 3787e52347bdSJani Nikula hpiosize=nn[KMG] The fixed amount of bus space which is 3788e52347bdSJani Nikula reserved for hotplug bridge's IO window. 3789e52347bdSJani Nikula Default size is 256 bytes. 3790d7b8a217SNicholas Johnson hpmmiosize=nn[KMG] The fixed amount of bus space which is 3791d7b8a217SNicholas Johnson reserved for hotplug bridge's MMIO window. 3792d7b8a217SNicholas Johnson Default size is 2 megabytes. 3793d7b8a217SNicholas Johnson hpmmioprefsize=nn[KMG] The fixed amount of bus space which is 3794d7b8a217SNicholas Johnson reserved for hotplug bridge's MMIO_PREF window. 3795d7b8a217SNicholas Johnson Default size is 2 megabytes. 3796e52347bdSJani Nikula hpmemsize=nn[KMG] The fixed amount of bus space which is 3797d7b8a217SNicholas Johnson reserved for hotplug bridge's MMIO and 3798d7b8a217SNicholas Johnson MMIO_PREF window. 3799e52347bdSJani Nikula Default size is 2 megabytes. 3800e52347bdSJani Nikula hpbussize=nn The minimum amount of additional bus numbers 3801e52347bdSJani Nikula reserved for buses below a hotplug bridge. 3802e52347bdSJani Nikula Default is 1. 3803e52347bdSJani Nikula realloc= Enable/disable reallocating PCI bridge resources 3804e52347bdSJani Nikula if allocations done by BIOS are too small to 3805e52347bdSJani Nikula accommodate resources required by all child 3806e52347bdSJani Nikula devices. 3807e52347bdSJani Nikula off: Turn realloc off 3808e52347bdSJani Nikula on: Turn realloc on 3809e52347bdSJani Nikula realloc same as realloc=on 3810e52347bdSJani Nikula noari do not use PCIe ARI. 3811cef74409SGil Kupfer noats [PCIE, Intel-IOMMU, AMD-IOMMU] 3812cef74409SGil Kupfer do not use PCIe ATS (and IOMMU device IOTLB). 3813e52347bdSJani Nikula pcie_scan_all Scan all possible PCIe devices. Otherwise we 3814e52347bdSJani Nikula only look for one device below a PCIe downstream 3815e52347bdSJani Nikula port. 3816f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= big_root_window Try to add a big 64bit memory window to the PCIe 3817f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= root complex on AMD CPUs. Some GFX hardware 3818f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= can resize a BAR to allow access to all VRAM. 3819f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= Adding the window is slightly risky (it may 3820f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= conflict with unreported devices), so this 3821f32ab754S=?UTF-8?q?Christian=20K=C3=B6nig?= taints the kernel. 3822aaca43fdSLogan Gunthorpe disable_acs_redir=<pci_dev>[; ...] 3823aaca43fdSLogan Gunthorpe Specify one or more PCI devices (in the format 3824aaca43fdSLogan Gunthorpe specified above) separated by semicolons. 3825aaca43fdSLogan Gunthorpe Each device specified will have the PCI ACS 3826aaca43fdSLogan Gunthorpe redirect capabilities forced off which will 3827aaca43fdSLogan Gunthorpe allow P2P traffic between devices through 3828aaca43fdSLogan Gunthorpe bridges without forcing it upstream. Note: 3829aaca43fdSLogan Gunthorpe this removes isolation between devices and 3830aaca43fdSLogan Gunthorpe may put more devices in an IOMMU group. 3831fbfe07d4SSebastian Ott force_floating [S390] Force usage of floating interrupts. 383256271303SSebastian Ott nomio [S390] Do not use MIO instructions. 3833de267a7cSPierre Morel norid [S390] ignore the RID field and force use of 3834de267a7cSPierre Morel one PCI domain per PCI function 3835e52347bdSJani Nikula 3836e52347bdSJani Nikula pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power 3837e52347bdSJani Nikula Management. 3838e52347bdSJani Nikula off Disable ASPM. 3839e52347bdSJani Nikula force Enable ASPM even on devices that claim not to support it. 3840e52347bdSJani Nikula WARNING: Forcing ASPM on may cause system lockups. 3841e52347bdSJani Nikula 38424c0fd764SBjorn Helgaas pcie_ports= [PCIE] PCIe port services handling: 38434c0fd764SBjorn Helgaas native Use native PCIe services (PME, AER, DPC, PCIe hotplug) 38444c0fd764SBjorn Helgaas even if the platform doesn't give the OS permission to 38454c0fd764SBjorn Helgaas use them. This may cause conflicts if the platform 38464c0fd764SBjorn Helgaas also tries to use these services. 384735a0b237SOlof Johansson dpc-native Use native PCIe service for DPC only. May 384835a0b237SOlof Johansson cause conflicts if firmware uses AER or DPC. 38494c0fd764SBjorn Helgaas compat Disable native PCIe services (PME, AER, DPC, PCIe 38504c0fd764SBjorn Helgaas hotplug). 3851e52347bdSJani Nikula 3852e52347bdSJani Nikula pcie_port_pm= [PCIE] PCIe port power management handling: 3853e52347bdSJani Nikula off Disable power management of all PCIe ports 3854e52347bdSJani Nikula force Forcibly enable power management of all PCIe ports 3855e52347bdSJani Nikula 3856e52347bdSJani Nikula pcie_pme= [PCIE,PM] Native PCIe PME signaling options: 3857e52347bdSJani Nikula nomsi Do not use MSI for native PCIe PME signaling (this makes 3858e52347bdSJani Nikula all PCIe root ports use INTx for all services). 3859e52347bdSJani Nikula 3860e52347bdSJani Nikula pcmv= [HW,PCMCIA] BadgePAD 4 3861e52347bdSJani Nikula 3862e52347bdSJani Nikula pd_ignore_unused 3863e52347bdSJani Nikula [PM] 3864e52347bdSJani Nikula Keep all power-domains already enabled by bootloader on, 3865e52347bdSJani Nikula even if no driver has claimed them. This is useful 3866e52347bdSJani Nikula for debug and development, but should not be 3867e52347bdSJani Nikula needed on a platform with proper driver support. 3868e52347bdSJani Nikula 3869e52347bdSJani Nikula pd. [PARIDE] 3870e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/paride.rst. 3871e52347bdSJani Nikula 3872e52347bdSJani Nikula pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at 3873e52347bdSJani Nikula boot time. 3874e52347bdSJani Nikula Format: { 0 | 1 } 3875e52347bdSJani Nikula See arch/parisc/kernel/pdc_chassis.c 3876e52347bdSJani Nikula 3877e52347bdSJani Nikula percpu_alloc= Select which percpu first chunk allocator to use. 3878e52347bdSJani Nikula Currently supported values are "embed" and "page". 3879e52347bdSJani Nikula Archs may support subset or none of the selections. 3880e52347bdSJani Nikula See comments in mm/percpu.c for details on each 3881e52347bdSJani Nikula allocator. This parameter is primarily for debugging 3882e52347bdSJani Nikula and performance comparison. 3883e52347bdSJani Nikula 3884e52347bdSJani Nikula pf. [PARIDE] 3885e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/paride.rst. 3886e52347bdSJani Nikula 3887e52347bdSJani Nikula pg. [PARIDE] 3888e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/paride.rst. 3889e52347bdSJani Nikula 3890e52347bdSJani Nikula pirq= [SMP,APIC] Manual mp-table setup 3891cb1aaebeSMauro Carvalho Chehab See Documentation/x86/i386/IO-APIC.rst. 3892e52347bdSJani Nikula 3893e52347bdSJani Nikula plip= [PPT,NET] Parallel port network link 3894e52347bdSJani Nikula Format: { parport<nr> | timid | 0 } 38953ba9b1b8STom Saeger See also Documentation/admin-guide/parport.rst. 3896e52347bdSJani Nikula 3897e52347bdSJani Nikula pmtmr= [X86] Manual setup of pmtmr I/O Port. 3898e52347bdSJani Nikula Override pmtimer IOPort with a hex value. 3899e52347bdSJani Nikula e.g. pmtmr=0x508 3900e52347bdSJani Nikula 3901db96a759SChen Yu pm_debug_messages [SUSPEND,KNL] 3902db96a759SChen Yu Enable suspend/resume debug messages during boot up. 3903db96a759SChen Yu 3904e52347bdSJani Nikula pnp.debug=1 [PNP] 3905e52347bdSJani Nikula Enable PNP debug messages (depends on the 3906e52347bdSJani Nikula CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time 3907e52347bdSJani Nikula via /sys/module/pnp/parameters/debug. We always show 3908e52347bdSJani Nikula current resource usage; turning this on also shows 3909e52347bdSJani Nikula possible settings and some assignment information. 3910e52347bdSJani Nikula 3911e52347bdSJani Nikula pnpacpi= [ACPI] 3912e52347bdSJani Nikula { off } 3913e52347bdSJani Nikula 3914e52347bdSJani Nikula pnpbios= [ISAPNP] 3915e52347bdSJani Nikula { on | off | curr | res | no-curr | no-res } 3916e52347bdSJani Nikula 3917e52347bdSJani Nikula pnp_reserve_irq= 3918e52347bdSJani Nikula [ISAPNP] Exclude IRQs for the autoconfiguration 3919e52347bdSJani Nikula 3920e52347bdSJani Nikula pnp_reserve_dma= 3921e52347bdSJani Nikula [ISAPNP] Exclude DMAs for the autoconfiguration 3922e52347bdSJani Nikula 3923e52347bdSJani Nikula pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration 3924e52347bdSJani Nikula Ranges are in pairs (I/O port base and size). 3925e52347bdSJani Nikula 3926e52347bdSJani Nikula pnp_reserve_mem= 3927e52347bdSJani Nikula [ISAPNP] Exclude memory regions for the 3928e52347bdSJani Nikula autoconfiguration. 3929e52347bdSJani Nikula Ranges are in pairs (memory base and size). 3930e52347bdSJani Nikula 3931e52347bdSJani Nikula ports= [IP_VS_FTP] IPVS ftp helper module 3932e52347bdSJani Nikula Default is 21. 3933e52347bdSJani Nikula Up to 8 (IP_VS_APP_MAX_PORTS) ports 3934e52347bdSJani Nikula may be specified. 3935e52347bdSJani Nikula Format: <port>,<port>.... 3936e52347bdSJani Nikula 3937c3cbd075SBalbir Singh powersave=off [PPC] This option disables power saving features. 3938c3cbd075SBalbir Singh It specifically disables cpuidle and sets the 3939c3cbd075SBalbir Singh platform machine description specific power_save 3940c3cbd075SBalbir Singh function to NULL. On Idle the CPU just reduces 3941c3cbd075SBalbir Singh execution priority. 3942c3cbd075SBalbir Singh 3943e52347bdSJani Nikula ppc_strict_facility_enable 3944e52347bdSJani Nikula [PPC] This option catches any kernel floating point, 3945e52347bdSJani Nikula Altivec, VSX and SPE outside of regions specifically 3946e52347bdSJani Nikula allowed (eg kernel_enable_fpu()/kernel_disable_fpu()). 3947e52347bdSJani Nikula There is some performance impact when enabling this. 3948e52347bdSJani Nikula 394907fd1761SCyril Bur ppc_tm= [PPC] 395007fd1761SCyril Bur Format: {"off"} 395107fd1761SCyril Bur Disable Hardware Transactional Memory 395207fd1761SCyril Bur 39536ef869e0SMichal Hocko preempt= [KNL] 39546ef869e0SMichal Hocko Select preemption mode if you have CONFIG_PREEMPT_DYNAMIC 39556ef869e0SMichal Hocko none - Limited to cond_resched() calls 39566ef869e0SMichal Hocko voluntary - Limited to cond_resched() and might_sleep() calls 39576ef869e0SMichal Hocko full - Any section that isn't explicitly preempt disabled 39586ef869e0SMichal Hocko can be preempted anytime. 39596ef869e0SMichal Hocko 3960e52347bdSJani Nikula print-fatal-signals= 3961e52347bdSJani Nikula [KNL] debug: print fatal signals 3962e52347bdSJani Nikula 3963e52347bdSJani Nikula If enabled, warn about various signal handling 3964e52347bdSJani Nikula related application anomalies: too many signals, 3965e52347bdSJani Nikula too many POSIX.1 timers, fatal signals causing a 3966e52347bdSJani Nikula coredump - etc. 3967e52347bdSJani Nikula 3968e52347bdSJani Nikula If you hit the warning due to signal overflow, 3969e52347bdSJani Nikula you might want to try "ulimit -i unlimited". 3970e52347bdSJani Nikula 3971e52347bdSJani Nikula default: off. 3972e52347bdSJani Nikula 3973e52347bdSJani Nikula printk.always_kmsg_dump= 3974e52347bdSJani Nikula Trigger kmsg_dump for cases other than kernel oops or 3975e52347bdSJani Nikula panics 3976e52347bdSJani Nikula Format: <bool> (1/Y/y=enable, 0/N/n=disable) 3977e52347bdSJani Nikula default: disabled 3978e52347bdSJani Nikula 3979e52347bdSJani Nikula printk.devkmsg={on,off,ratelimit} 3980e52347bdSJani Nikula Control writing to /dev/kmsg. 3981e52347bdSJani Nikula on - unlimited logging to /dev/kmsg from userspace 3982e52347bdSJani Nikula off - logging to /dev/kmsg disabled 3983e52347bdSJani Nikula ratelimit - ratelimit the logging 3984e52347bdSJani Nikula Default: ratelimit 3985e52347bdSJani Nikula 3986e52347bdSJani Nikula printk.time= Show timing data prefixed to each printk message line 3987e52347bdSJani Nikula Format: <bool> (1/Y/y=enable, 0/N/n=disable) 3988e52347bdSJani Nikula 3989e52347bdSJani Nikula processor.max_cstate= [HW,ACPI] 3990e52347bdSJani Nikula Limit processor to maximum C-state 3991e52347bdSJani Nikula max_cstate=9 overrides any DMI blacklist limit. 3992e52347bdSJani Nikula 3993e52347bdSJani Nikula processor.nocst [HW,ACPI] 3994e52347bdSJani Nikula Ignore the _CST method to determine C-states, 3995e52347bdSJani Nikula instead using the legacy FADT method 3996e52347bdSJani Nikula 3997e52347bdSJani Nikula profile= [KNL] Enable kernel profiling via /proc/profile 3998e7e61fc0SRandy Dunlap Format: [<profiletype>,]<number> 3999e7e61fc0SRandy Dunlap Param: <profiletype>: "schedule", "sleep", or "kvm" 4000e7e61fc0SRandy Dunlap [defaults to kernel profiling] 4001e52347bdSJani Nikula Param: "schedule" - profile schedule points. 4002e52347bdSJani Nikula Param: "sleep" - profile D-state sleeping (millisecs). 4003e52347bdSJani Nikula Requires CONFIG_SCHEDSTATS 4004e52347bdSJani Nikula Param: "kvm" - profile VM exits. 4005e7e61fc0SRandy Dunlap Param: <number> - step/bucket size as a power of 2 for 4006e7e61fc0SRandy Dunlap statistical time based profiling. 4007e52347bdSJani Nikula 40086b99e6e6SRandy Dunlap prompt_ramdisk= [RAM] [Deprecated] 4009e52347bdSJani Nikula 4010ecdc5d84SVasily Gorbik prot_virt= [S390] enable hosting protected virtual machines 4011ecdc5d84SVasily Gorbik isolated from the hypervisor (if hardware supports 4012ecdc5d84SVasily Gorbik that). 4013ecdc5d84SVasily Gorbik Format: <bool> 4014ecdc5d84SVasily Gorbik 4015e0c27447SJohannes Weiner psi= [KNL] Enable or disable pressure stall information 4016e0c27447SJohannes Weiner tracking. 4017e0c27447SJohannes Weiner Format: <bool> 4018e0c27447SJohannes Weiner 4019e52347bdSJani Nikula psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to 4020e52347bdSJani Nikula probe for; one of (bare|imps|exps|lifebook|any). 4021e52347bdSJani Nikula psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports 4022e52347bdSJani Nikula per second. 4023e52347bdSJani Nikula psmouse.resetafter= [HW,MOUSE] 4024e52347bdSJani Nikula Try to reset the device after so many bad packets 4025e52347bdSJani Nikula (0 = never). 4026e52347bdSJani Nikula psmouse.resolution= 4027e52347bdSJani Nikula [HW,MOUSE] Set desired mouse resolution, in dpi. 4028e52347bdSJani Nikula psmouse.smartscroll= 4029e52347bdSJani Nikula [HW,MOUSE] Controls Logitech smartscroll autorepeat. 4030e52347bdSJani Nikula 0 = disabled, 1 = enabled (default). 4031e52347bdSJani Nikula 4032e52347bdSJani Nikula pstore.backend= Specify the name of the pstore backend to use 4033e52347bdSJani Nikula 4034e52347bdSJani Nikula pt. [PARIDE] 4035e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/paride.rst. 4036e52347bdSJani Nikula 4037be3a5b0eSRandy Dunlap pti= [X86-64] Control Page Table Isolation of user and 403801c9b17bSDave Hansen kernel address spaces. Disabling this feature 403901c9b17bSDave Hansen removes hardening, but improves performance of 404001c9b17bSDave Hansen system calls and interrupts. 404101c9b17bSDave Hansen 404201c9b17bSDave Hansen on - unconditionally enable 404301c9b17bSDave Hansen off - unconditionally disable 404401c9b17bSDave Hansen auto - kernel detects whether your CPU model is 404501c9b17bSDave Hansen vulnerable to issues that PTI mitigates 404601c9b17bSDave Hansen 404701c9b17bSDave Hansen Not specifying this option is equivalent to pti=auto. 404801c9b17bSDave Hansen 4049be3a5b0eSRandy Dunlap nopti [X86-64] 405001c9b17bSDave Hansen Equivalent to pti=off 405141f4c20bSBorislav Petkov 4052e52347bdSJani Nikula pty.legacy_count= 4053e52347bdSJani Nikula [KNL] Number of legacy pty's. Overwrites compiled-in 4054e52347bdSJani Nikula default number. 4055e52347bdSJani Nikula 4056e52347bdSJani Nikula quiet [KNL] Disable most log messages 4057e52347bdSJani Nikula 4058e52347bdSJani Nikula r128= [HW,DRM] 4059e52347bdSJani Nikula 4060e52347bdSJani Nikula raid= [HW,RAID] 4061e52347bdSJani Nikula See Documentation/admin-guide/md.rst. 4062e52347bdSJani Nikula 4063e52347bdSJani Nikula ramdisk_size= [RAM] Sizes of RAM disks in kilobytes 4064e7751617SMauro Carvalho Chehab See Documentation/admin-guide/blockdev/ramdisk.rst. 4065e52347bdSJani Nikula 40666b99e6e6SRandy Dunlap ramdisk_start= [RAM] RAM disk image start address 40676b99e6e6SRandy Dunlap 40689b254366SKees Cook random.trust_cpu={on,off} 40699b254366SKees Cook [KNL] Enable or disable trusting the use of the 40709b254366SKees Cook CPU's random number generator (if available) to 40719b254366SKees Cook fully seed the kernel's CRNG. Default is controlled 40729b254366SKees Cook by CONFIG_RANDOM_TRUST_CPU. 40739b254366SKees Cook 4074011d8261SBorislav Petkov ras=option[,option,...] [KNL] RAS-specific options 4075011d8261SBorislav Petkov 4076011d8261SBorislav Petkov cec_disable [X86] 4077011d8261SBorislav Petkov Disable the Correctable Errors Collector, 4078011d8261SBorislav Petkov see CONFIG_RAS_CEC help text. 4079011d8261SBorislav Petkov 4080e52347bdSJani Nikula rcu_nocbs= [KNL] 4081da8739f2SPaul E. McKenney The argument is a cpu list, as described above, 4082da8739f2SPaul E. McKenney except that the string "all" can be used to 4083da8739f2SPaul E. McKenney specify every CPU on the system. 4084e52347bdSJani Nikula 4085e52347bdSJani Nikula In kernels built with CONFIG_RCU_NOCB_CPU=y, set 4086e52347bdSJani Nikula the specified list of CPUs to be no-callback CPUs. 408777095901SPaul E. McKenney Invocation of these CPUs' RCU callbacks will be 408877095901SPaul E. McKenney offloaded to "rcuox/N" kthreads created for that 408977095901SPaul E. McKenney purpose, where "x" is "p" for RCU-preempt, and 409077095901SPaul E. McKenney "s" for RCU-sched, and "N" is the CPU number. 409177095901SPaul E. McKenney This reduces OS jitter on the offloaded CPUs, 409277095901SPaul E. McKenney which can be useful for HPC and real-time 409377095901SPaul E. McKenney workloads. It can also improve energy efficiency 409477095901SPaul E. McKenney for asymmetric multiprocessors. 4095e52347bdSJani Nikula 4096e52347bdSJani Nikula rcu_nocb_poll [KNL] 4097e52347bdSJani Nikula Rather than requiring that offloaded CPUs 4098e52347bdSJani Nikula (specified by rcu_nocbs= above) explicitly 4099e52347bdSJani Nikula awaken the corresponding "rcuoN" kthreads, 4100e52347bdSJani Nikula make these kthreads poll for callbacks. 4101e52347bdSJani Nikula This improves the real-time response for the 4102e52347bdSJani Nikula offloaded CPUs by relieving them of the need to 4103e52347bdSJani Nikula wake up the corresponding kthread, but degrades 4104e52347bdSJani Nikula energy efficiency by requiring that the kthreads 4105e52347bdSJani Nikula periodically wake up to do the polling. 4106e52347bdSJani Nikula 4107e52347bdSJani Nikula rcutree.blimit= [KNL] 4108e52347bdSJani Nikula Set maximum number of finished RCU callbacks to 4109e52347bdSJani Nikula process in one batch. 4110e52347bdSJani Nikula 4111e52347bdSJani Nikula rcutree.dump_tree= [KNL] 4112e52347bdSJani Nikula Dump the structure of the rcu_node combining tree 4113e52347bdSJani Nikula out at early boot. This is used for diagnostic 4114e52347bdSJani Nikula purposes, to verify correct tree setup. 4115e52347bdSJani Nikula 4116e52347bdSJani Nikula rcutree.gp_cleanup_delay= [KNL] 4117e52347bdSJani Nikula Set the number of jiffies to delay each step of 411890040c9eSPaul E. McKenney RCU grace-period cleanup. 4119e52347bdSJani Nikula 4120e52347bdSJani Nikula rcutree.gp_init_delay= [KNL] 4121e52347bdSJani Nikula Set the number of jiffies to delay each step of 412290040c9eSPaul E. McKenney RCU grace-period initialization. 4123e52347bdSJani Nikula 4124e52347bdSJani Nikula rcutree.gp_preinit_delay= [KNL] 4125e52347bdSJani Nikula Set the number of jiffies to delay each step of 4126e52347bdSJani Nikula RCU grace-period pre-initialization, that is, 4127e52347bdSJani Nikula the propagation of recent CPU-hotplug changes up 412890040c9eSPaul E. McKenney the rcu_node combining tree. 4129e52347bdSJani Nikula 413048d07c04SSebastian Andrzej Siewior rcutree.use_softirq= [KNL] 413148d07c04SSebastian Andrzej Siewior If set to zero, move all RCU_SOFTIRQ processing to 413248d07c04SSebastian Andrzej Siewior per-CPU rcuc kthreads. Defaults to a non-zero 413348d07c04SSebastian Andrzej Siewior value, meaning that RCU_SOFTIRQ is used by default. 413448d07c04SSebastian Andrzej Siewior Specify rcutree.use_softirq=0 to use rcuc kthreads. 413548d07c04SSebastian Andrzej Siewior 41368b9a0eccSScott Wood But note that CONFIG_PREEMPT_RT=y kernels disable 41378b9a0eccSScott Wood this kernel boot parameter, forcibly setting it 41388b9a0eccSScott Wood to zero. 41398b9a0eccSScott Wood 4140e52347bdSJani Nikula rcutree.rcu_fanout_exact= [KNL] 4141e52347bdSJani Nikula Disable autobalancing of the rcu_node combining 4142e52347bdSJani Nikula tree. This is used by rcutorture, and might 4143e52347bdSJani Nikula possibly be useful for architectures having high 4144e52347bdSJani Nikula cache-to-cache transfer latencies. 4145e52347bdSJani Nikula 4146e52347bdSJani Nikula rcutree.rcu_fanout_leaf= [KNL] 4147e52347bdSJani Nikula Change the number of CPUs assigned to each 4148e52347bdSJani Nikula leaf rcu_node structure. Useful for very 4149e52347bdSJani Nikula large systems, which will choose the value 64, 4150e52347bdSJani Nikula and for NUMA systems with large remote-access 4151e52347bdSJani Nikula latencies, which will choose a value aligned 4152e52347bdSJani Nikula with the appropriate hardware boundaries. 4153e52347bdSJani Nikula 415453c72b59SUladzislau Rezki (Sony) rcutree.rcu_min_cached_objs= [KNL] 415553c72b59SUladzislau Rezki (Sony) Minimum number of objects which are cached and 415653c72b59SUladzislau Rezki (Sony) maintained per one CPU. Object size is equal 415753c72b59SUladzislau Rezki (Sony) to PAGE_SIZE. The cache allows to reduce the 415853c72b59SUladzislau Rezki (Sony) pressure to page allocator, also it makes the 415953c72b59SUladzislau Rezki (Sony) whole algorithm to behave better in low memory 416053c72b59SUladzislau Rezki (Sony) condition. 416153c72b59SUladzislau Rezki (Sony) 4162e52347bdSJani Nikula rcutree.jiffies_till_first_fqs= [KNL] 4163e52347bdSJani Nikula Set delay from grace-period initialization to 4164e52347bdSJani Nikula first attempt to force quiescent states. 4165e52347bdSJani Nikula Units are jiffies, minimum value is zero, 4166e52347bdSJani Nikula and maximum value is HZ. 4167e52347bdSJani Nikula 4168e52347bdSJani Nikula rcutree.jiffies_till_next_fqs= [KNL] 4169e52347bdSJani Nikula Set delay between subsequent attempts to force 4170e52347bdSJani Nikula quiescent states. Units are jiffies, minimum 4171e52347bdSJani Nikula value is one, and maximum value is HZ. 4172e52347bdSJani Nikula 41731a4762b9SPaul E. McKenney rcutree.jiffies_till_sched_qs= [KNL] 41741a4762b9SPaul E. McKenney Set required age in jiffies for a 41751a4762b9SPaul E. McKenney given grace period before RCU starts 41761a4762b9SPaul E. McKenney soliciting quiescent-state help from 41771a4762b9SPaul E. McKenney rcu_note_context_switch() and cond_resched(). 41781a4762b9SPaul E. McKenney If not specified, the kernel will calculate 41791a4762b9SPaul E. McKenney a value based on the most recent settings 41801a4762b9SPaul E. McKenney of rcutree.jiffies_till_first_fqs 41811a4762b9SPaul E. McKenney and rcutree.jiffies_till_next_fqs. 41821a4762b9SPaul E. McKenney This calculated value may be viewed in 41831a4762b9SPaul E. McKenney rcutree.jiffies_to_sched_qs. Any attempt to set 41841a4762b9SPaul E. McKenney rcutree.jiffies_to_sched_qs will be cheerfully 41851a4762b9SPaul E. McKenney overwritten. 41861a4762b9SPaul E. McKenney 4187e52347bdSJani Nikula rcutree.kthread_prio= [KNL,BOOT] 4188e52347bdSJani Nikula Set the SCHED_FIFO priority of the RCU per-CPU 4189e52347bdSJani Nikula kthreads (rcuc/N). This value is also used for 4190e52347bdSJani Nikula the priority of the RCU boost threads (rcub/N) 4191e52347bdSJani Nikula and for the RCU grace-period kthreads (rcu_bh, 4192e52347bdSJani Nikula rcu_preempt, and rcu_sched). If RCU_BOOST is 4193e52347bdSJani Nikula set, valid values are 1-99 and the default is 1 4194e52347bdSJani Nikula (the least-favored priority). Otherwise, when 4195e52347bdSJani Nikula RCU_BOOST is not set, valid values are 0-99 and 4196e52347bdSJani Nikula the default is zero (non-realtime operation). 4197e52347bdSJani Nikula 4198f7c612b0SPaul E. McKenney rcutree.rcu_nocb_gp_stride= [KNL] 4199f7c612b0SPaul E. McKenney Set the number of NOCB callback kthreads in 4200f7c612b0SPaul E. McKenney each group, which defaults to the square root 4201f7c612b0SPaul E. McKenney of the number of CPUs. Larger numbers reduce 4202f7c612b0SPaul E. McKenney the wakeup overhead on the global grace-period 4203f7c612b0SPaul E. McKenney kthread, but increases that same overhead on 4204f7c612b0SPaul E. McKenney each group's NOCB grace-period kthread. 4205e52347bdSJani Nikula 4206e52347bdSJani Nikula rcutree.qhimark= [KNL] 4207e52347bdSJani Nikula Set threshold of queued RCU callbacks beyond which 4208e52347bdSJani Nikula batch limiting is disabled. 4209e52347bdSJani Nikula 4210e52347bdSJani Nikula rcutree.qlowmark= [KNL] 4211e52347bdSJani Nikula Set threshold of queued RCU callbacks below which 4212e52347bdSJani Nikula batch limiting is re-enabled. 4213e52347bdSJani Nikula 4214b2b00ddfSPaul E. McKenney rcutree.qovld= [KNL] 4215b2b00ddfSPaul E. McKenney Set threshold of queued RCU callbacks beyond which 4216b2b00ddfSPaul E. McKenney RCU's force-quiescent-state scan will aggressively 4217b2b00ddfSPaul E. McKenney enlist help from cond_resched() and sched IPIs to 4218b2b00ddfSPaul E. McKenney help CPUs more quickly reach quiescent states. 4219b2b00ddfSPaul E. McKenney Set to less than zero to make this be set based 4220b2b00ddfSPaul E. McKenney on rcutree.qhimark at boot time and to zero to 4221b2b00ddfSPaul E. McKenney disable more aggressive help enlistment. 4222b2b00ddfSPaul E. McKenney 4223e52347bdSJani Nikula rcutree.rcu_idle_gp_delay= [KNL] 4224e52347bdSJani Nikula Set wakeup interval for idle CPUs that have 4225e52347bdSJani Nikula RCU callbacks (RCU_FAST_NO_HZ=y). 4226e52347bdSJani Nikula 4227e3c50dfbSPaul E. McKenney rcutree.rcu_kick_kthreads= [KNL] 4228e3c50dfbSPaul E. McKenney Cause the grace-period kthread to get an extra 4229e3c50dfbSPaul E. McKenney wake_up() if it sleeps three times longer than 4230e3c50dfbSPaul E. McKenney it should at force-quiescent-state time. 4231e3c50dfbSPaul E. McKenney This wake_up() will be accompanied by a 4232e3c50dfbSPaul E. McKenney WARN_ONCE() splat and an ftrace_dump(). 4233e3c50dfbSPaul E. McKenney 42343d29aaf1SPaul E. McKenney rcutree.rcu_unlock_delay= [KNL] 42353d29aaf1SPaul E. McKenney In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels, 42363d29aaf1SPaul E. McKenney this specifies an rcu_read_unlock()-time delay 42373d29aaf1SPaul E. McKenney in microseconds. This defaults to zero. 42383d29aaf1SPaul E. McKenney Larger delays increase the probability of 42393d29aaf1SPaul E. McKenney catching RCU pointer leaks, that is, buggy use 42403d29aaf1SPaul E. McKenney of RCU-protected pointers after the relevant 42413d29aaf1SPaul E. McKenney rcu_read_unlock() has completed. 42423d29aaf1SPaul E. McKenney 42432ccaff10SPaul E. McKenney rcutree.sysrq_rcu= [KNL] 42442ccaff10SPaul E. McKenney Commandeer a sysrq key to dump out Tree RCU's 42452ccaff10SPaul E. McKenney rcu_node tree with an eye towards determining 42462ccaff10SPaul E. McKenney why a new grace period has not yet started. 42472ccaff10SPaul E. McKenney 42484e88ec4aSPaul E. McKenney rcuscale.gp_async= [KNL] 4249881ed593SPaul E. McKenney Measure performance of asynchronous 4250881ed593SPaul E. McKenney grace-period primitives such as call_rcu(). 4251881ed593SPaul E. McKenney 42524e88ec4aSPaul E. McKenney rcuscale.gp_async_max= [KNL] 4253881ed593SPaul E. McKenney Specify the maximum number of outstanding 4254881ed593SPaul E. McKenney callbacks per writer thread. When a writer 4255881ed593SPaul E. McKenney thread exceeds this limit, it invokes the 4256881ed593SPaul E. McKenney corresponding flavor of rcu_barrier() to allow 4257881ed593SPaul E. McKenney previously posted callbacks to drain. 4258881ed593SPaul E. McKenney 42594e88ec4aSPaul E. McKenney rcuscale.gp_exp= [KNL] 4260e52347bdSJani Nikula Measure performance of expedited synchronous 4261e52347bdSJani Nikula grace-period primitives. 4262e52347bdSJani Nikula 42634e88ec4aSPaul E. McKenney rcuscale.holdoff= [KNL] 4264e52347bdSJani Nikula Set test-start holdoff period. The purpose of 4265e52347bdSJani Nikula this parameter is to delay the start of the 4266e52347bdSJani Nikula test until boot completes in order to avoid 4267e52347bdSJani Nikula interference. 4268e52347bdSJani Nikula 42694e88ec4aSPaul E. McKenney rcuscale.kfree_rcu_test= [KNL] 4270e6e78b00SJoel Fernandes (Google) Set to measure performance of kfree_rcu() flooding. 4271e6e78b00SJoel Fernandes (Google) 42724e88ec4aSPaul E. McKenney rcuscale.kfree_nthreads= [KNL] 4273e6e78b00SJoel Fernandes (Google) The number of threads running loops of kfree_rcu(). 4274e6e78b00SJoel Fernandes (Google) 42754e88ec4aSPaul E. McKenney rcuscale.kfree_alloc_num= [KNL] 4276e6e78b00SJoel Fernandes (Google) Number of allocations and frees done in an iteration. 4277e6e78b00SJoel Fernandes (Google) 42784e88ec4aSPaul E. McKenney rcuscale.kfree_loops= [KNL] 42794e88ec4aSPaul E. McKenney Number of loops doing rcuscale.kfree_alloc_num number 4280e6e78b00SJoel Fernandes (Google) of allocations and frees. 4281e6e78b00SJoel Fernandes (Google) 42824e88ec4aSPaul E. McKenney rcuscale.nreaders= [KNL] 4283e52347bdSJani Nikula Set number of RCU readers. The value -1 selects 4284e52347bdSJani Nikula N, where N is the number of CPUs. A value 4285e52347bdSJani Nikula "n" less than -1 selects N-n+1, where N is again 4286e52347bdSJani Nikula the number of CPUs. For example, -2 selects N 4287e52347bdSJani Nikula (the number of CPUs), -3 selects N+1, and so on. 4288e52347bdSJani Nikula A value of "n" less than or equal to -N selects 4289e52347bdSJani Nikula a single reader. 4290e52347bdSJani Nikula 42914e88ec4aSPaul E. McKenney rcuscale.nwriters= [KNL] 4292e52347bdSJani Nikula Set number of RCU writers. The values operate 42934e88ec4aSPaul E. McKenney the same as for rcuscale.nreaders. 4294e52347bdSJani Nikula N, where N is the number of CPUs 4295e52347bdSJani Nikula 42964e88ec4aSPaul E. McKenney rcuscale.perf_type= [KNL] 4297820687a7SPaul E. McKenney Specify the RCU implementation to test. 4298820687a7SPaul E. McKenney 42994e88ec4aSPaul E. McKenney rcuscale.shutdown= [KNL] 4300e52347bdSJani Nikula Shut the system down after performance tests 4301e52347bdSJani Nikula complete. This is useful for hands-off automated 4302e52347bdSJani Nikula testing. 4303e52347bdSJani Nikula 43044e88ec4aSPaul E. McKenney rcuscale.verbose= [KNL] 4305e52347bdSJani Nikula Enable additional printk() statements. 4306e52347bdSJani Nikula 43074e88ec4aSPaul E. McKenney rcuscale.writer_holdoff= [KNL] 4308820687a7SPaul E. McKenney Write-side holdoff between grace periods, 4309820687a7SPaul E. McKenney in microseconds. The default of zero says 4310820687a7SPaul E. McKenney no holdoff. 4311820687a7SPaul E. McKenney 4312e52347bdSJani Nikula rcutorture.fqs_duration= [KNL] 4313e52347bdSJani Nikula Set duration of force_quiescent_state bursts 4314e52347bdSJani Nikula in microseconds. 4315e52347bdSJani Nikula 4316e52347bdSJani Nikula rcutorture.fqs_holdoff= [KNL] 4317e52347bdSJani Nikula Set holdoff time within force_quiescent_state bursts 4318e52347bdSJani Nikula in microseconds. 4319e52347bdSJani Nikula 4320e52347bdSJani Nikula rcutorture.fqs_stutter= [KNL] 4321e52347bdSJani Nikula Set wait time between force_quiescent_state bursts 4322e52347bdSJani Nikula in seconds. 4323e52347bdSJani Nikula 4324ed8f6fb2SPaul E. McKenney rcutorture.fwd_progress= [KNL] 4325ed8f6fb2SPaul E. McKenney Enable RCU grace-period forward-progress testing 4326ed8f6fb2SPaul E. McKenney for the types of RCU supporting this notion. 4327ed8f6fb2SPaul E. McKenney 4328ed8f6fb2SPaul E. McKenney rcutorture.fwd_progress_div= [KNL] 4329ed8f6fb2SPaul E. McKenney Specify the fraction of a CPU-stall-warning 4330ed8f6fb2SPaul E. McKenney period to do tight-loop forward-progress testing. 4331ed8f6fb2SPaul E. McKenney 4332ed8f6fb2SPaul E. McKenney rcutorture.fwd_progress_holdoff= [KNL] 4333ed8f6fb2SPaul E. McKenney Number of seconds to wait between successive 4334ed8f6fb2SPaul E. McKenney forward-progress tests. 4335ed8f6fb2SPaul E. McKenney 4336ed8f6fb2SPaul E. McKenney rcutorture.fwd_progress_need_resched= [KNL] 4337ed8f6fb2SPaul E. McKenney Enclose cond_resched() calls within checks for 4338ed8f6fb2SPaul E. McKenney need_resched() during tight-loop forward-progress 4339ed8f6fb2SPaul E. McKenney testing. 4340ed8f6fb2SPaul E. McKenney 4341e52347bdSJani Nikula rcutorture.gp_cond= [KNL] 4342e52347bdSJani Nikula Use conditional/asynchronous update-side 4343e52347bdSJani Nikula primitives, if available. 4344e52347bdSJani Nikula 4345e52347bdSJani Nikula rcutorture.gp_exp= [KNL] 4346e52347bdSJani Nikula Use expedited update-side primitives, if available. 4347e52347bdSJani Nikula 4348e52347bdSJani Nikula rcutorture.gp_normal= [KNL] 4349e52347bdSJani Nikula Use normal (non-expedited) asynchronous 4350e52347bdSJani Nikula update-side primitives, if available. 4351e52347bdSJani Nikula 4352e52347bdSJani Nikula rcutorture.gp_sync= [KNL] 4353e52347bdSJani Nikula Use normal (non-expedited) synchronous 4354e52347bdSJani Nikula update-side primitives, if available. If all 4355e52347bdSJani Nikula of rcutorture.gp_cond=, rcutorture.gp_exp=, 4356e52347bdSJani Nikula rcutorture.gp_normal=, and rcutorture.gp_sync= 4357e52347bdSJani Nikula are zero, rcutorture acts as if is interpreted 4358e52347bdSJani Nikula they are all non-zero. 4359e52347bdSJani Nikula 4360d6855142SPaul E. McKenney rcutorture.irqreader= [KNL] 4361d6855142SPaul E. McKenney Run RCU readers from irq handlers, or, more 4362d6855142SPaul E. McKenney accurately, from a timer handler. Not all RCU 4363d6855142SPaul E. McKenney flavors take kindly to this sort of thing. 4364d6855142SPaul E. McKenney 4365d6855142SPaul E. McKenney rcutorture.leakpointer= [KNL] 4366d6855142SPaul E. McKenney Leak an RCU-protected pointer out of the reader. 4367d6855142SPaul E. McKenney This can of course result in splats, and is 4368d6855142SPaul E. McKenney intended to test the ability of things like 4369d6855142SPaul E. McKenney CONFIG_RCU_STRICT_GRACE_PERIOD=y to detect 4370d6855142SPaul E. McKenney such leaks. 4371d6855142SPaul E. McKenney 4372e52347bdSJani Nikula rcutorture.n_barrier_cbs= [KNL] 4373e52347bdSJani Nikula Set callbacks/threads for rcu_barrier() testing. 4374e52347bdSJani Nikula 4375e52347bdSJani Nikula rcutorture.nfakewriters= [KNL] 4376e52347bdSJani Nikula Set number of concurrent RCU writers. These just 4377e52347bdSJani Nikula stress RCU, they don't participate in the actual 4378e52347bdSJani Nikula test, hence the "fake". 4379e52347bdSJani Nikula 43802c4319bdSPaul E. McKenney rcutorture.nocbs_nthreads= [KNL] 43812c4319bdSPaul E. McKenney Set number of RCU callback-offload togglers. 43822c4319bdSPaul E. McKenney Zero (the default) disables toggling. 43832c4319bdSPaul E. McKenney 43842c4319bdSPaul E. McKenney rcutorture.nocbs_toggle= [KNL] 43852c4319bdSPaul E. McKenney Set the delay in milliseconds between successive 43862c4319bdSPaul E. McKenney callback-offload toggling attempts. 43872c4319bdSPaul E. McKenney 4388e52347bdSJani Nikula rcutorture.nreaders= [KNL] 4389e52347bdSJani Nikula Set number of RCU readers. The value -1 selects 4390e52347bdSJani Nikula N-1, where N is the number of CPUs. A value 4391e52347bdSJani Nikula "n" less than -1 selects N-n-2, where N is again 4392e52347bdSJani Nikula the number of CPUs. For example, -2 selects N 4393e52347bdSJani Nikula (the number of CPUs), -3 selects N+1, and so on. 4394e52347bdSJani Nikula 4395e52347bdSJani Nikula rcutorture.object_debug= [KNL] 4396e52347bdSJani Nikula Enable debug-object double-call_rcu() testing. 4397e52347bdSJani Nikula 4398e52347bdSJani Nikula rcutorture.onoff_holdoff= [KNL] 4399e52347bdSJani Nikula Set time (s) after boot for CPU-hotplug testing. 4400e52347bdSJani Nikula 4401e52347bdSJani Nikula rcutorture.onoff_interval= [KNL] 4402028be12bSPaul E. McKenney Set time (jiffies) between CPU-hotplug operations, 4403028be12bSPaul E. McKenney or zero to disable CPU-hotplug testing. 4404e52347bdSJani Nikula 44054a5f133cSPaul E. McKenney rcutorture.read_exit= [KNL] 44064a5f133cSPaul E. McKenney Set the number of read-then-exit kthreads used 44074a5f133cSPaul E. McKenney to test the interaction of RCU updaters and 44084a5f133cSPaul E. McKenney task-exit processing. 44094a5f133cSPaul E. McKenney 44104a5f133cSPaul E. McKenney rcutorture.read_exit_burst= [KNL] 44114a5f133cSPaul E. McKenney The number of times in a given read-then-exit 44124a5f133cSPaul E. McKenney episode that a set of read-then-exit kthreads 44134a5f133cSPaul E. McKenney is spawned. 44144a5f133cSPaul E. McKenney 44154a5f133cSPaul E. McKenney rcutorture.read_exit_delay= [KNL] 44164a5f133cSPaul E. McKenney The delay, in seconds, between successive 44174a5f133cSPaul E. McKenney read-then-exit testing episodes. 44184a5f133cSPaul E. McKenney 4419e52347bdSJani Nikula rcutorture.shuffle_interval= [KNL] 4420e52347bdSJani Nikula Set task-shuffle interval (s). Shuffling tasks 4421e52347bdSJani Nikula allows some CPUs to go into dyntick-idle mode 4422e52347bdSJani Nikula during the rcutorture test. 4423e52347bdSJani Nikula 4424e52347bdSJani Nikula rcutorture.shutdown_secs= [KNL] 4425e52347bdSJani Nikula Set time (s) after boot system shutdown. This 4426e52347bdSJani Nikula is useful for hands-off automated testing. 4427e52347bdSJani Nikula 4428e52347bdSJani Nikula rcutorture.stall_cpu= [KNL] 4429e52347bdSJani Nikula Duration of CPU stall (s) to test RCU CPU stall 4430e52347bdSJani Nikula warnings, zero to disable. 4431e52347bdSJani Nikula 443219a8ff95SPaul E. McKenney rcutorture.stall_cpu_block= [KNL] 443319a8ff95SPaul E. McKenney Sleep while stalling if set. This will result 443419a8ff95SPaul E. McKenney in warnings from preemptible RCU in addition 443519a8ff95SPaul E. McKenney to any other stall-related activity. 443619a8ff95SPaul E. McKenney 4437e52347bdSJani Nikula rcutorture.stall_cpu_holdoff= [KNL] 4438e52347bdSJani Nikula Time to wait (s) after boot before inducing stall. 4439e52347bdSJani Nikula 44402b1516e5SPaul E. McKenney rcutorture.stall_cpu_irqsoff= [KNL] 44412b1516e5SPaul E. McKenney Disable interrupts while stalling if set. 44422b1516e5SPaul E. McKenney 444355b2dcf5SPaul E. McKenney rcutorture.stall_gp_kthread= [KNL] 444455b2dcf5SPaul E. McKenney Duration (s) of forced sleep within RCU 444555b2dcf5SPaul E. McKenney grace-period kthread to test RCU CPU stall 444655b2dcf5SPaul E. McKenney warnings, zero to disable. If both stall_cpu 444755b2dcf5SPaul E. McKenney and stall_gp_kthread are specified, the 444855b2dcf5SPaul E. McKenney kthread is starved first, then the CPU. 444955b2dcf5SPaul E. McKenney 4450e52347bdSJani Nikula rcutorture.stat_interval= [KNL] 4451e52347bdSJani Nikula Time (s) between statistics printk()s. 4452e52347bdSJani Nikula 4453e52347bdSJani Nikula rcutorture.stutter= [KNL] 4454e52347bdSJani Nikula Time (s) to stutter testing, for example, specifying 4455e52347bdSJani Nikula five seconds causes the test to run for five seconds, 4456e52347bdSJani Nikula wait for five seconds, and so on. This tests RCU's 4457e52347bdSJani Nikula ability to transition abruptly to and from idle. 4458e52347bdSJani Nikula 4459e52347bdSJani Nikula rcutorture.test_boost= [KNL] 4460e52347bdSJani Nikula Test RCU priority boosting? 0=no, 1=maybe, 2=yes. 4461e52347bdSJani Nikula "Maybe" means test if the RCU implementation 4462e52347bdSJani Nikula under test support RCU priority boosting. 4463e52347bdSJani Nikula 4464e52347bdSJani Nikula rcutorture.test_boost_duration= [KNL] 4465e52347bdSJani Nikula Duration (s) of each individual boost test. 4466e52347bdSJani Nikula 4467e52347bdSJani Nikula rcutorture.test_boost_interval= [KNL] 4468e52347bdSJani Nikula Interval (s) between each boost test. 4469e52347bdSJani Nikula 4470e52347bdSJani Nikula rcutorture.test_no_idle_hz= [KNL] 4471e52347bdSJani Nikula Test RCU's dyntick-idle handling. See also the 4472e52347bdSJani Nikula rcutorture.shuffle_interval parameter. 4473e52347bdSJani Nikula 4474e52347bdSJani Nikula rcutorture.torture_type= [KNL] 4475e52347bdSJani Nikula Specify the RCU implementation to test. 4476e52347bdSJani Nikula 4477e52347bdSJani Nikula rcutorture.verbose= [KNL] 4478e52347bdSJani Nikula Enable additional printk() statements. 4479e52347bdSJani Nikula 4480cdc694b2SPaul E. McKenney rcupdate.rcu_cpu_stall_ftrace_dump= [KNL] 4481cdc694b2SPaul E. McKenney Dump ftrace buffer after reporting RCU CPU 4482cdc694b2SPaul E. McKenney stall warning. 4483cdc694b2SPaul E. McKenney 4484e52347bdSJani Nikula rcupdate.rcu_cpu_stall_suppress= [KNL] 4485e52347bdSJani Nikula Suppress RCU CPU stall warning messages. 4486e52347bdSJani Nikula 448758c53360SPaul E. McKenney rcupdate.rcu_cpu_stall_suppress_at_boot= [KNL] 448858c53360SPaul E. McKenney Suppress RCU CPU stall warning messages and 448958c53360SPaul E. McKenney rcutorture writer stall warnings that occur 449058c53360SPaul E. McKenney during early boot, that is, during the time 449158c53360SPaul E. McKenney before the init task is spawned. 449258c53360SPaul E. McKenney 4493e52347bdSJani Nikula rcupdate.rcu_cpu_stall_timeout= [KNL] 4494e52347bdSJani Nikula Set timeout for RCU CPU stall warning messages. 4495e52347bdSJani Nikula 4496e52347bdSJani Nikula rcupdate.rcu_expedited= [KNL] 4497e52347bdSJani Nikula Use expedited grace-period primitives, for 4498e52347bdSJani Nikula example, synchronize_rcu_expedited() instead 4499e52347bdSJani Nikula of synchronize_rcu(). This reduces latency, 4500e52347bdSJani Nikula but can increase CPU utilization, degrade 4501e52347bdSJani Nikula real-time latency, and degrade energy efficiency. 4502e52347bdSJani Nikula No effect on CONFIG_TINY_RCU kernels. 4503e52347bdSJani Nikula 4504e52347bdSJani Nikula rcupdate.rcu_normal= [KNL] 4505e52347bdSJani Nikula Use only normal grace-period primitives, 4506e52347bdSJani Nikula for example, synchronize_rcu() instead of 4507e52347bdSJani Nikula synchronize_rcu_expedited(). This improves 4508e52347bdSJani Nikula real-time latency, CPU utilization, and 4509e52347bdSJani Nikula energy efficiency, but can expose users to 4510e52347bdSJani Nikula increased grace-period latency. This parameter 4511e52347bdSJani Nikula overrides rcupdate.rcu_expedited. No effect on 4512e52347bdSJani Nikula CONFIG_TINY_RCU kernels. 4513e52347bdSJani Nikula 4514e52347bdSJani Nikula rcupdate.rcu_normal_after_boot= [KNL] 4515e52347bdSJani Nikula Once boot has completed (that is, after 4516e52347bdSJani Nikula rcu_end_inkernel_boot() has been invoked), use 4517e52347bdSJani Nikula only normal grace-period primitives. No effect 4518e52347bdSJani Nikula on CONFIG_TINY_RCU kernels. 4519e52347bdSJani Nikula 452036221e10SJulia Cartwright But note that CONFIG_PREEMPT_RT=y kernels enables 452136221e10SJulia Cartwright this kernel boot parameter, forcibly setting 452236221e10SJulia Cartwright it to the value one, that is, converting any 452336221e10SJulia Cartwright post-boot attempt at an expedited RCU grace 452436221e10SJulia Cartwright period to instead use normal non-expedited 452536221e10SJulia Cartwright grace-period processing. 452636221e10SJulia Cartwright 4527b0afa0f0SPaul E. McKenney rcupdate.rcu_task_ipi_delay= [KNL] 4528b0afa0f0SPaul E. McKenney Set time in jiffies during which RCU tasks will 4529b0afa0f0SPaul E. McKenney avoid sending IPIs, starting with the beginning 4530b0afa0f0SPaul E. McKenney of a given grace period. Setting a large 4531b0afa0f0SPaul E. McKenney number avoids disturbing real-time workloads, 4532b0afa0f0SPaul E. McKenney but lengthens grace periods. 4533b0afa0f0SPaul E. McKenney 4534e52347bdSJani Nikula rcupdate.rcu_task_stall_timeout= [KNL] 4535e52347bdSJani Nikula Set timeout in jiffies for RCU task stall warning 4536e52347bdSJani Nikula messages. Disable with a value less than or equal 4537e52347bdSJani Nikula to zero. 4538e52347bdSJani Nikula 4539e52347bdSJani Nikula rcupdate.rcu_self_test= [KNL] 4540e52347bdSJani Nikula Run the RCU early boot self tests 4541e52347bdSJani Nikula 4542e52347bdSJani Nikula rdinit= [KNL] 4543e52347bdSJani Nikula Format: <full_path> 4544e52347bdSJani Nikula Run specified binary instead of /init from the ramdisk, 4545e52347bdSJani Nikula used for early userspace startup. See initrd. 4546e52347bdSJani Nikula 4547c49a0a80STom Lendacky rdrand= [X86] 4548c49a0a80STom Lendacky force - Override the decision by the kernel to hide the 4549c49a0a80STom Lendacky advertisement of RDRAND support (this affects 4550c49a0a80STom Lendacky certain AMD processors because of buggy BIOS 4551c49a0a80STom Lendacky support, specifically around the suspend/resume 4552c49a0a80STom Lendacky path). 4553c49a0a80STom Lendacky 45541d9807fcSTony Luck rdt= [HW,X86,RDT] 45551d9807fcSTony Luck Turn on/off individual RDT features. List is: 455631516de3SFenghua Yu cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp, 455731516de3SFenghua Yu mba. 45581d9807fcSTony Luck E.g. to turn on cmt and turn off mba use: 45591d9807fcSTony Luck rdt=cmt,!mba 45601d9807fcSTony Luck 4561e52347bdSJani Nikula reboot= [KNL] 4562e52347bdSJani Nikula Format (x86 or x86_64): 4563e52347bdSJani Nikula [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \ 4564e52347bdSJani Nikula [[,]s[mp]#### \ 4565e52347bdSJani Nikula [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \ 4566e52347bdSJani Nikula [[,]f[orce] 4567b287a25aSAaro Koskinen Where reboot_mode is one of warm (soft) or cold (hard) or gpio 4568b287a25aSAaro Koskinen (prefix with 'panic_' to set mode for panic 4569b287a25aSAaro Koskinen reboot only), 4570e52347bdSJani Nikula reboot_type is one of bios, acpi, kbd, triple, efi, or pci, 4571e52347bdSJani Nikula reboot_force is either force or not specified, 4572e52347bdSJani Nikula reboot_cpu is s[mp]#### with #### being the processor 4573e52347bdSJani Nikula to be used for rebooting. 4574e52347bdSJani Nikula 45751fbeb3a8SPaul E. McKenney refscale.holdoff= [KNL] 4576847dd70aSPaul E. McKenney Set test-start holdoff period. The purpose of 4577847dd70aSPaul E. McKenney this parameter is to delay the start of the 4578847dd70aSPaul E. McKenney test until boot completes in order to avoid 4579847dd70aSPaul E. McKenney interference. 4580847dd70aSPaul E. McKenney 45811fbeb3a8SPaul E. McKenney refscale.loops= [KNL] 4582847dd70aSPaul E. McKenney Set the number of loops over the synchronization 4583847dd70aSPaul E. McKenney primitive under test. Increasing this number 4584847dd70aSPaul E. McKenney reduces noise due to loop start/end overhead, 4585847dd70aSPaul E. McKenney but the default has already reduced the per-pass 4586847dd70aSPaul E. McKenney noise to a handful of picoseconds on ca. 2020 4587847dd70aSPaul E. McKenney x86 laptops. 4588847dd70aSPaul E. McKenney 45891fbeb3a8SPaul E. McKenney refscale.nreaders= [KNL] 4590847dd70aSPaul E. McKenney Set number of readers. The default value of -1 4591847dd70aSPaul E. McKenney selects N, where N is roughly 75% of the number 4592847dd70aSPaul E. McKenney of CPUs. A value of zero is an interesting choice. 4593847dd70aSPaul E. McKenney 45941fbeb3a8SPaul E. McKenney refscale.nruns= [KNL] 4595847dd70aSPaul E. McKenney Set number of runs, each of which is dumped onto 4596847dd70aSPaul E. McKenney the console log. 4597847dd70aSPaul E. McKenney 45981fbeb3a8SPaul E. McKenney refscale.readdelay= [KNL] 4599847dd70aSPaul E. McKenney Set the read-side critical-section duration, 4600847dd70aSPaul E. McKenney measured in microseconds. 4601847dd70aSPaul E. McKenney 46021fbeb3a8SPaul E. McKenney refscale.scale_type= [KNL] 46031fbeb3a8SPaul E. McKenney Specify the read-protection implementation to test. 46041fbeb3a8SPaul E. McKenney 46051fbeb3a8SPaul E. McKenney refscale.shutdown= [KNL] 4606847dd70aSPaul E. McKenney Shut down the system at the end of the performance 4607847dd70aSPaul E. McKenney test. This defaults to 1 (shut it down) when 46084e88ec4aSPaul E. McKenney refscale is built into the kernel and to 0 (leave 46094e88ec4aSPaul E. McKenney it running) when refscale is built as a module. 4610847dd70aSPaul E. McKenney 46111fbeb3a8SPaul E. McKenney refscale.verbose= [KNL] 4612847dd70aSPaul E. McKenney Enable additional printk() statements. 4613847dd70aSPaul E. McKenney 4614e76506f0SPaul E. McKenney refscale.verbose_batched= [KNL] 4615e76506f0SPaul E. McKenney Batch the additional printk() statements. If zero 4616e76506f0SPaul E. McKenney (the default) or negative, print everything. Otherwise, 4617e76506f0SPaul E. McKenney print every Nth verbose statement, where N is the value 4618e76506f0SPaul E. McKenney specified. 4619e76506f0SPaul E. McKenney 4620e52347bdSJani Nikula relax_domain_level= 4621e52347bdSJani Nikula [KNL, SMP] Set scheduler's default relax_domain_level. 4622da82c92fSMauro Carvalho Chehab See Documentation/admin-guide/cgroup-v1/cpusets.rst. 4623e52347bdSJani Nikula 4624ffd2e8dfSBjorn Helgaas reserve= [KNL,BUGS] Force kernel to ignore I/O ports or memory 4625ffd2e8dfSBjorn Helgaas Format: <base1>,<size1>[,<base2>,<size2>,...] 4626ffd2e8dfSBjorn Helgaas Reserve I/O ports or memory so the kernel won't use 4627ffd2e8dfSBjorn Helgaas them. If <base> is less than 0x10000, the region 4628ffd2e8dfSBjorn Helgaas is assumed to be I/O ports; otherwise it is memory. 4629e52347bdSJani Nikula 4630e52347bdSJani Nikula reservetop= [X86-32] 4631e52347bdSJani Nikula Format: nn[KMG] 4632e52347bdSJani Nikula Reserves a hole at the top of the kernel virtual 4633e52347bdSJani Nikula address space. 4634e52347bdSJani Nikula 4635e52347bdSJani Nikula reservelow= [X86] 4636e52347bdSJani Nikula Format: nn[K] 4637e52347bdSJani Nikula Set the amount of memory to reserve for BIOS at 4638e52347bdSJani Nikula the bottom of the address space. 4639e52347bdSJani Nikula 4640e52347bdSJani Nikula reset_devices [KNL] Force drivers to reset the underlying device 4641e52347bdSJani Nikula during initialization. 4642e52347bdSJani Nikula 4643e52347bdSJani Nikula resume= [SWSUSP] 4644e52347bdSJani Nikula Specify the partition device for software suspend 4645e52347bdSJani Nikula Format: 4646e52347bdSJani Nikula {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>} 4647e52347bdSJani Nikula 4648e52347bdSJani Nikula resume_offset= [SWSUSP] 4649e52347bdSJani Nikula Specify the offset from the beginning of the partition 4650e52347bdSJani Nikula given by "resume=" at which the swap header is located, 4651e52347bdSJani Nikula in <PAGE_SIZE> units (needed only for swap files). 4652151f4e2bSMauro Carvalho Chehab See Documentation/power/swsusp-and-swap-files.rst 4653e52347bdSJani Nikula 4654e52347bdSJani Nikula resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to 4655e52347bdSJani Nikula read the resume files 4656e52347bdSJani Nikula 4657e52347bdSJani Nikula resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up. 4658e52347bdSJani Nikula Useful for devices that are detected asynchronously 4659e52347bdSJani Nikula (e.g. USB and MMC devices). 4660e52347bdSJani Nikula 4661e52347bdSJani Nikula hibernate= [HIBERNATION] 4662e52347bdSJani Nikula noresume Don't check if there's a hibernation image 4663e52347bdSJani Nikula present during boot. 4664e52347bdSJani Nikula nocompress Don't compress/decompress hibernation images. 4665e52347bdSJani Nikula no Disable hibernation and resume. 4666e52347bdSJani Nikula protect_image Turn on image protection during restoration 4667e52347bdSJani Nikula (that will set all pages holding image data 4668e52347bdSJani Nikula during restoration read-only). 4669e52347bdSJani Nikula 4670e52347bdSJani Nikula retain_initrd [RAM] Keep initrd memory after extraction 4671e52347bdSJani Nikula 4672e52347bdSJani Nikula rfkill.default_state= 4673e52347bdSJani Nikula 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm, 4674e52347bdSJani Nikula etc. communication is blocked by default. 4675e52347bdSJani Nikula 1 Unblocked. 4676e52347bdSJani Nikula 4677e52347bdSJani Nikula rfkill.master_switch_mode= 4678e52347bdSJani Nikula 0 The "airplane mode" button does nothing. 4679e52347bdSJani Nikula 1 The "airplane mode" button toggles between everything 4680e52347bdSJani Nikula blocked and the previous configuration. 4681e52347bdSJani Nikula 2 The "airplane mode" button toggles between everything 4682e52347bdSJani Nikula blocked and everything unblocked. 4683e52347bdSJani Nikula 4684e52347bdSJani Nikula rhash_entries= [KNL,NET] 4685e52347bdSJani Nikula Set number of hash buckets for route cache 4686e52347bdSJani Nikula 4687e16fd002SGrzegorz Andrejczuk ring3mwait=disable 4688e16fd002SGrzegorz Andrejczuk [KNL] Disable ring 3 MONITOR/MWAIT feature on supported 4689e16fd002SGrzegorz Andrejczuk CPUs. 4690e16fd002SGrzegorz Andrejczuk 4691e52347bdSJani Nikula ro [KNL] Mount root device read-only on boot 4692e52347bdSJani Nikula 4693e52347bdSJani Nikula rodata= [KNL] 4694e52347bdSJani Nikula on Mark read-only kernel memory as read-only (default). 4695e52347bdSJani Nikula off Leave read-only kernel memory writable for debugging. 4696e52347bdSJani Nikula 4697e52347bdSJani Nikula rockchip.usb_uart 4698e52347bdSJani Nikula Enable the uart passthrough on the designated usb port 4699e52347bdSJani Nikula on Rockchip SoCs. When active, the signals of the 4700e52347bdSJani Nikula debug-uart get routed to the D+ and D- pins of the usb 4701e52347bdSJani Nikula port and the regular usb controller gets disabled. 4702e52347bdSJani Nikula 4703e52347bdSJani Nikula root= [KNL] Root filesystem 4704e52347bdSJani Nikula See name_to_dev_t comment in init/do_mounts.c. 4705e52347bdSJani Nikula 4706e52347bdSJani Nikula rootdelay= [KNL] Delay (in seconds) to pause before attempting to 4707e52347bdSJani Nikula mount the root filesystem 4708e52347bdSJani Nikula 4709e52347bdSJani Nikula rootflags= [KNL] Set root filesystem mount option string 4710e52347bdSJani Nikula 4711e52347bdSJani Nikula rootfstype= [KNL] Set root filesystem type 4712e52347bdSJani Nikula 4713e52347bdSJani Nikula rootwait [KNL] Wait (indefinitely) for root device to show up. 4714e52347bdSJani Nikula Useful for devices that are detected asynchronously 4715e52347bdSJani Nikula (e.g. USB and MMC devices). 4716e52347bdSJani Nikula 4717e52347bdSJani Nikula rproc_mem=nn[KMG][@address] 4718e52347bdSJani Nikula [KNL,ARM,CMA] Remoteproc physical memory block. 4719e52347bdSJani Nikula Memory area to be used by remote processor image, 4720e52347bdSJani Nikula managed by CMA. 4721e52347bdSJani Nikula 4722e52347bdSJani Nikula rw [KNL] Mount root device read-write on boot 4723e52347bdSJani Nikula 4724e52347bdSJani Nikula S [KNL] Run init in single mode 4725e52347bdSJani Nikula 4726e52347bdSJani Nikula s390_iommu= [HW,S390] 4727e52347bdSJani Nikula Set s390 IOTLB flushing mode 4728e52347bdSJani Nikula strict 4729e52347bdSJani Nikula With strict flushing every unmap operation will result in 4730e52347bdSJani Nikula an IOTLB flush. Default is lazy flushing before reuse, 4731e52347bdSJani Nikula which is faster. 4732e52347bdSJani Nikula 4733e52347bdSJani Nikula sa1100ir [NET] 4734e52347bdSJani Nikula See drivers/net/irda/sa1100_ir.c. 4735e52347bdSJani Nikula 4736e52347bdSJani Nikula sbni= [NET] Granch SBNI12 leased line adapter 4737e52347bdSJani Nikula 4738e52347bdSJani Nikula sched_debug [KNL] Enables verbose scheduler debug messages. 4739e52347bdSJani Nikula 4740e52347bdSJani Nikula schedstats= [KNL,X86] Enable or disable scheduled statistics. 4741e52347bdSJani Nikula Allowed values are enable and disable. This feature 4742e52347bdSJani Nikula incurs a small amount of overhead in the scheduler 4743e52347bdSJani Nikula but is useful for debugging and performance tuning. 4744e52347bdSJani Nikula 474505289b90SThara Gopinath sched_thermal_decay_shift= 474605289b90SThara Gopinath [KNL, SMP] Set a decay shift for scheduler thermal 474705289b90SThara Gopinath pressure signal. Thermal pressure signal follows the 474805289b90SThara Gopinath default decay period of other scheduler pelt 474905289b90SThara Gopinath signals(usually 32 ms but configurable). Setting 475005289b90SThara Gopinath sched_thermal_decay_shift will left shift the decay 475105289b90SThara Gopinath period for the thermal pressure signal by the shift 475205289b90SThara Gopinath value. 475305289b90SThara Gopinath i.e. with the default pelt decay period of 32 ms 475405289b90SThara Gopinath sched_thermal_decay_shift thermal pressure decay pr 475505289b90SThara Gopinath 1 64 ms 475605289b90SThara Gopinath 2 128 ms 475705289b90SThara Gopinath and so on. 475805289b90SThara Gopinath Format: integer between 0 and 10 475905289b90SThara Gopinath Default is 0. 476005289b90SThara Gopinath 4761e9d338a0SPaul E. McKenney scftorture.holdoff= [KNL] 4762e9d338a0SPaul E. McKenney Number of seconds to hold off before starting 4763e9d338a0SPaul E. McKenney test. Defaults to zero for module insertion and 4764e9d338a0SPaul E. McKenney to 10 seconds for built-in smp_call_function() 4765e9d338a0SPaul E. McKenney tests. 4766e9d338a0SPaul E. McKenney 4767e9d338a0SPaul E. McKenney scftorture.longwait= [KNL] 4768e9d338a0SPaul E. McKenney Request ridiculously long waits randomly selected 4769e9d338a0SPaul E. McKenney up to the chosen limit in seconds. Zero (the 4770e9d338a0SPaul E. McKenney default) disables this feature. Please note 4771e9d338a0SPaul E. McKenney that requesting even small non-zero numbers of 4772e9d338a0SPaul E. McKenney seconds can result in RCU CPU stall warnings, 4773e9d338a0SPaul E. McKenney softlockup complaints, and so on. 4774e9d338a0SPaul E. McKenney 4775e9d338a0SPaul E. McKenney scftorture.nthreads= [KNL] 4776e9d338a0SPaul E. McKenney Number of kthreads to spawn to invoke the 4777e9d338a0SPaul E. McKenney smp_call_function() family of functions. 4778e9d338a0SPaul E. McKenney The default of -1 specifies a number of kthreads 4779e9d338a0SPaul E. McKenney equal to the number of CPUs. 4780e9d338a0SPaul E. McKenney 4781e9d338a0SPaul E. McKenney scftorture.onoff_holdoff= [KNL] 4782e9d338a0SPaul E. McKenney Number seconds to wait after the start of the 4783e9d338a0SPaul E. McKenney test before initiating CPU-hotplug operations. 4784e9d338a0SPaul E. McKenney 4785e9d338a0SPaul E. McKenney scftorture.onoff_interval= [KNL] 4786e9d338a0SPaul E. McKenney Number seconds to wait between successive 4787e9d338a0SPaul E. McKenney CPU-hotplug operations. Specifying zero (which 4788e9d338a0SPaul E. McKenney is the default) disables CPU-hotplug operations. 4789e9d338a0SPaul E. McKenney 4790e9d338a0SPaul E. McKenney scftorture.shutdown_secs= [KNL] 4791e9d338a0SPaul E. McKenney The number of seconds following the start of the 4792e9d338a0SPaul E. McKenney test after which to shut down the system. The 4793e9d338a0SPaul E. McKenney default of zero avoids shutting down the system. 4794e9d338a0SPaul E. McKenney Non-zero values are useful for automated tests. 4795e9d338a0SPaul E. McKenney 4796e9d338a0SPaul E. McKenney scftorture.stat_interval= [KNL] 4797e9d338a0SPaul E. McKenney The number of seconds between outputting the 4798e9d338a0SPaul E. McKenney current test statistics to the console. A value 4799e9d338a0SPaul E. McKenney of zero disables statistics output. 4800e9d338a0SPaul E. McKenney 4801e9d338a0SPaul E. McKenney scftorture.stutter_cpus= [KNL] 4802e9d338a0SPaul E. McKenney The number of jiffies to wait between each change 4803e9d338a0SPaul E. McKenney to the set of CPUs under test. 4804e9d338a0SPaul E. McKenney 4805e9d338a0SPaul E. McKenney scftorture.use_cpus_read_lock= [KNL] 4806e9d338a0SPaul E. McKenney Use use_cpus_read_lock() instead of the default 4807e9d338a0SPaul E. McKenney preempt_disable() to disable CPU hotplug 4808e9d338a0SPaul E. McKenney while invoking one of the smp_call_function*() 4809e9d338a0SPaul E. McKenney functions. 4810e9d338a0SPaul E. McKenney 4811e9d338a0SPaul E. McKenney scftorture.verbose= [KNL] 4812e9d338a0SPaul E. McKenney Enable additional printk() statements. 4813e9d338a0SPaul E. McKenney 4814e9d338a0SPaul E. McKenney scftorture.weight_single= [KNL] 4815e9d338a0SPaul E. McKenney The probability weighting to use for the 4816e9d338a0SPaul E. McKenney smp_call_function_single() function with a zero 4817e9d338a0SPaul E. McKenney "wait" parameter. A value of -1 selects the 4818e9d338a0SPaul E. McKenney default if all other weights are -1. However, 4819e9d338a0SPaul E. McKenney if at least one weight has some other value, a 4820e9d338a0SPaul E. McKenney value of -1 will instead select a weight of zero. 4821e9d338a0SPaul E. McKenney 4822e9d338a0SPaul E. McKenney scftorture.weight_single_wait= [KNL] 4823e9d338a0SPaul E. McKenney The probability weighting to use for the 4824e9d338a0SPaul E. McKenney smp_call_function_single() function with a 4825e9d338a0SPaul E. McKenney non-zero "wait" parameter. See weight_single. 4826e9d338a0SPaul E. McKenney 4827e9d338a0SPaul E. McKenney scftorture.weight_many= [KNL] 4828e9d338a0SPaul E. McKenney The probability weighting to use for the 4829e9d338a0SPaul E. McKenney smp_call_function_many() function with a zero 4830e9d338a0SPaul E. McKenney "wait" parameter. See weight_single. 4831e9d338a0SPaul E. McKenney Note well that setting a high probability for 4832e9d338a0SPaul E. McKenney this weighting can place serious IPI load 4833e9d338a0SPaul E. McKenney on the system. 4834e9d338a0SPaul E. McKenney 4835e9d338a0SPaul E. McKenney scftorture.weight_many_wait= [KNL] 4836e9d338a0SPaul E. McKenney The probability weighting to use for the 4837e9d338a0SPaul E. McKenney smp_call_function_many() function with a 4838e9d338a0SPaul E. McKenney non-zero "wait" parameter. See weight_single 4839e9d338a0SPaul E. McKenney and weight_many. 4840e9d338a0SPaul E. McKenney 4841e9d338a0SPaul E. McKenney scftorture.weight_all= [KNL] 4842e9d338a0SPaul E. McKenney The probability weighting to use for the 4843e9d338a0SPaul E. McKenney smp_call_function_all() function with a zero 4844e9d338a0SPaul E. McKenney "wait" parameter. See weight_single and 4845e9d338a0SPaul E. McKenney weight_many. 4846e9d338a0SPaul E. McKenney 4847e9d338a0SPaul E. McKenney scftorture.weight_all_wait= [KNL] 4848e9d338a0SPaul E. McKenney The probability weighting to use for the 4849e9d338a0SPaul E. McKenney smp_call_function_all() function with a 4850e9d338a0SPaul E. McKenney non-zero "wait" parameter. See weight_single 4851e9d338a0SPaul E. McKenney and weight_many. 4852e9d338a0SPaul E. McKenney 4853e52347bdSJani Nikula skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate 4854e52347bdSJani Nikula xtime_lock contention on larger systems, and/or RCU lock 4855e52347bdSJani Nikula contention on all systems with CONFIG_MAXSMP set. 4856e52347bdSJani Nikula Format: { "0" | "1" } 4857e52347bdSJani Nikula 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1" 4858e52347bdSJani Nikula 1 -- enable. 4859e52347bdSJani Nikula Note: increases power consumption, thus should only be 4860e52347bdSJani Nikula enabled if running jitter sensitive (HPC/RT) workloads. 4861e52347bdSJani Nikula 486289a9684eSKees Cook security= [SECURITY] Choose a legacy "major" security module to 486389a9684eSKees Cook enable at boot. This has been deprecated by the 486489a9684eSKees Cook "lsm=" parameter. 4865e52347bdSJani Nikula 4866e52347bdSJani Nikula selinux= [SELINUX] Disable or enable SELinux at boot time. 4867e52347bdSJani Nikula Format: { "0" | "1" } 4868e52347bdSJani Nikula See security/selinux/Kconfig help text. 4869e52347bdSJani Nikula 0 -- disable. 4870e52347bdSJani Nikula 1 -- enable. 4871d41415ebSStephen Smalley Default value is 1. 4872e52347bdSJani Nikula 4873e52347bdSJani Nikula apparmor= [APPARMOR] Disable or enable AppArmor at boot time 4874e52347bdSJani Nikula Format: { "0" | "1" } 4875e52347bdSJani Nikula See security/apparmor/Kconfig help text 4876e52347bdSJani Nikula 0 -- disable. 4877e52347bdSJani Nikula 1 -- enable. 4878e52347bdSJani Nikula Default value is set via kernel config option. 4879e52347bdSJani Nikula 4880e52347bdSJani Nikula serialnumber [BUGS=X86-32] 4881e52347bdSJani Nikula 4882e52347bdSJani Nikula shapers= [NET] 4883e52347bdSJani Nikula Maximal number of shapers. 4884e52347bdSJani Nikula 4885e52347bdSJani Nikula simeth= [IA-64] 4886e52347bdSJani Nikula simscsi= 4887e52347bdSJani Nikula 4888e52347bdSJani Nikula slram= [HW,MTD] 4889e52347bdSJani Nikula 4890e52347bdSJani Nikula slab_nomerge [MM] 4891e52347bdSJani Nikula Disable merging of slabs with similar size. May be 4892e52347bdSJani Nikula necessary if there is some reason to distinguish 48937660a6fdSKees Cook allocs to different slabs, especially in hardened 48947660a6fdSKees Cook environments where the risk of heap overflows and 48957660a6fdSKees Cook layout control by attackers can usually be 48967660a6fdSKees Cook frustrated by disabling merging. This will reduce 48977660a6fdSKees Cook most of the exposure of a heap attack to a single 48987660a6fdSKees Cook cache (risks via metadata attacks are mostly 48997660a6fdSKees Cook unchanged). Debug options disable merging on their 49007660a6fdSKees Cook own. 4901ad56b738SMike Rapoport For more information see Documentation/vm/slub.rst. 4902e52347bdSJani Nikula 4903e52347bdSJani Nikula slab_max_order= [MM, SLAB] 4904e52347bdSJani Nikula Determines the maximum allowed order for slabs. 4905e52347bdSJani Nikula A high setting may cause OOMs due to memory 4906e52347bdSJani Nikula fragmentation. Defaults to 1 for systems with 4907e52347bdSJani Nikula more than 32MB of RAM, 0 otherwise. 4908e52347bdSJani Nikula 4909e17f1dfbSVlastimil Babka slub_debug[=options[,slabs][;[options[,slabs]]...] [MM, SLUB] 4910e52347bdSJani Nikula Enabling slub_debug allows one to determine the 4911e52347bdSJani Nikula culprit if slab objects become corrupted. Enabling 4912e52347bdSJani Nikula slub_debug can create guard zones around objects and 4913e52347bdSJani Nikula may poison objects when not in use. Also tracks the 4914e52347bdSJani Nikula last alloc / free. For more information see 4915ad56b738SMike Rapoport Documentation/vm/slub.rst. 4916e52347bdSJani Nikula 4917e52347bdSJani Nikula slub_max_order= [MM, SLUB] 4918e52347bdSJani Nikula Determines the maximum allowed order for slabs. 4919e52347bdSJani Nikula A high setting may cause OOMs due to memory 4920e52347bdSJani Nikula fragmentation. For more information see 4921ad56b738SMike Rapoport Documentation/vm/slub.rst. 4922e52347bdSJani Nikula 4923e52347bdSJani Nikula slub_min_objects= [MM, SLUB] 4924e52347bdSJani Nikula The minimum number of objects per slab. SLUB will 4925e52347bdSJani Nikula increase the slab order up to slub_max_order to 4926e52347bdSJani Nikula generate a sufficiently large slab able to contain 4927e52347bdSJani Nikula the number of objects indicated. The higher the number 4928e52347bdSJani Nikula of objects the smaller the overhead of tracking slabs 4929e52347bdSJani Nikula and the less frequently locks need to be acquired. 4930ad56b738SMike Rapoport For more information see Documentation/vm/slub.rst. 4931e52347bdSJani Nikula 4932e52347bdSJani Nikula slub_min_order= [MM, SLUB] 4933e52347bdSJani Nikula Determines the minimum page order for slabs. Must be 4934e52347bdSJani Nikula lower than slub_max_order. 4935ad56b738SMike Rapoport For more information see Documentation/vm/slub.rst. 4936e52347bdSJani Nikula 4937e52347bdSJani Nikula slub_nomerge [MM, SLUB] 4938e52347bdSJani Nikula Same with slab_nomerge. This is supported for legacy. 4939e52347bdSJani Nikula See slab_nomerge for more information. 4940e52347bdSJani Nikula 4941e52347bdSJani Nikula smart2= [HW] 4942e52347bdSJani Nikula Format: <io1>[,<io2>[,...,<io8>]] 4943e52347bdSJani Nikula 4944e52347bdSJani Nikula smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices 4945e52347bdSJani Nikula smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port 4946e52347bdSJani Nikula smsc-ircc2.ircc_sir= [HW] SIR base I/O port 4947e52347bdSJani Nikula smsc-ircc2.ircc_fir= [HW] FIR base I/O port 4948e52347bdSJani Nikula smsc-ircc2.ircc_irq= [HW] IRQ line 4949e52347bdSJani Nikula smsc-ircc2.ircc_dma= [HW] DMA channel 4950e52347bdSJani Nikula smsc-ircc2.ircc_transceiver= [HW] Transceiver type: 4951e52347bdSJani Nikula 0: Toshiba Satellite 1800 (GP data pin select) 4952e52347bdSJani Nikula 1: Fast pin select (default) 4953e52347bdSJani Nikula 2: ATC IRMode 4954e52347bdSJani Nikula 4955e52347bdSJani Nikula smt [KNL,S390] Set the maximum number of threads (logical 4956e52347bdSJani Nikula CPUs) to use per physical CPU on systems capable of 4957e52347bdSJani Nikula symmetric multithreading (SMT). Will be capped to the 4958e52347bdSJani Nikula actual hardware limit. 4959e52347bdSJani Nikula Format: <integer> 4960e52347bdSJani Nikula Default: -1 (no limit) 4961e52347bdSJani Nikula 4962e52347bdSJani Nikula softlockup_panic= 4963e52347bdSJani Nikula [KNL] Should the soft-lockup detector generate panics. 4964f117955aSGuilherme G. Piccoli Format: 0 | 1 4965e52347bdSJani Nikula 4966f117955aSGuilherme G. Piccoli A value of 1 instructs the soft-lockup detector 49670a07bef6SGuilherme G. Piccoli to panic the machine when a soft-lockup occurs. It is 49680a07bef6SGuilherme G. Piccoli also controlled by the kernel.softlockup_panic sysctl 49690a07bef6SGuilherme G. Piccoli and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the 49700a07bef6SGuilherme G. Piccoli respective build-time switch to that functionality. 49713ce62385SBorislav Petkov 4972e52347bdSJani Nikula softlockup_all_cpu_backtrace= 4973e52347bdSJani Nikula [KNL] Should the soft-lockup detector generate 4974e52347bdSJani Nikula backtraces on all cpus. 4975f117955aSGuilherme G. Piccoli Format: 0 | 1 4976e52347bdSJani Nikula 4977e52347bdSJani Nikula sonypi.*= [HW] Sony Programmable I/O Control Device driver 49789e1cbedeSMauro Carvalho Chehab See Documentation/admin-guide/laptops/sonypi.rst 4979e52347bdSJani Nikula 4980da285121SDavid Woodhouse spectre_v2= [X86] Control mitigation of Spectre variant 2 4981da285121SDavid Woodhouse (indirect branch speculation) vulnerability. 4982fa1202efSThomas Gleixner The default operation protects the kernel from 4983fa1202efSThomas Gleixner user space attacks. 4984da285121SDavid Woodhouse 4985fa1202efSThomas Gleixner on - unconditionally enable, implies 4986fa1202efSThomas Gleixner spectre_v2_user=on 4987fa1202efSThomas Gleixner off - unconditionally disable, implies 4988fa1202efSThomas Gleixner spectre_v2_user=off 4989da285121SDavid Woodhouse auto - kernel detects whether your CPU model is 4990da285121SDavid Woodhouse vulnerable 4991da285121SDavid Woodhouse 4992da285121SDavid Woodhouse Selecting 'on' will, and 'auto' may, choose a 4993da285121SDavid Woodhouse mitigation method at run time according to the 4994da285121SDavid Woodhouse CPU, the available microcode, the setting of the 4995da285121SDavid Woodhouse CONFIG_RETPOLINE configuration option, and the 4996da285121SDavid Woodhouse compiler with which the kernel was built. 4997da285121SDavid Woodhouse 4998fa1202efSThomas Gleixner Selecting 'on' will also enable the mitigation 4999fa1202efSThomas Gleixner against user space to user space task attacks. 5000fa1202efSThomas Gleixner 5001fa1202efSThomas Gleixner Selecting 'off' will disable both the kernel and 5002fa1202efSThomas Gleixner the user space protections. 5003fa1202efSThomas Gleixner 5004da285121SDavid Woodhouse Specific mitigations can also be selected manually: 5005da285121SDavid Woodhouse 5006da285121SDavid Woodhouse retpoline - replace indirect branches 5007da285121SDavid Woodhouse retpoline,generic - google's original retpoline 5008da285121SDavid Woodhouse retpoline,amd - AMD-specific minimal thunk 5009da285121SDavid Woodhouse 5010da285121SDavid Woodhouse Not specifying this option is equivalent to 5011da285121SDavid Woodhouse spectre_v2=auto. 5012da285121SDavid Woodhouse 5013fa1202efSThomas Gleixner spectre_v2_user= 5014fa1202efSThomas Gleixner [X86] Control mitigation of Spectre variant 2 5015fa1202efSThomas Gleixner (indirect branch speculation) vulnerability between 5016fa1202efSThomas Gleixner user space tasks 5017fa1202efSThomas Gleixner 5018fa1202efSThomas Gleixner on - Unconditionally enable mitigations. Is 5019fa1202efSThomas Gleixner enforced by spectre_v2=on 5020fa1202efSThomas Gleixner 5021fa1202efSThomas Gleixner off - Unconditionally disable mitigations. Is 5022fa1202efSThomas Gleixner enforced by spectre_v2=off 5023fa1202efSThomas Gleixner 50247cc765a6SThomas Gleixner prctl - Indirect branch speculation is enabled, 50257cc765a6SThomas Gleixner but mitigation can be enabled via prctl 50267cc765a6SThomas Gleixner per thread. The mitigation control state 50277cc765a6SThomas Gleixner is inherited on fork. 50287cc765a6SThomas Gleixner 502955a97402SThomas Gleixner prctl,ibpb 503055a97402SThomas Gleixner - Like "prctl" above, but only STIBP is 503155a97402SThomas Gleixner controlled per thread. IBPB is issued 503255a97402SThomas Gleixner always when switching between different user 503355a97402SThomas Gleixner space processes. 503455a97402SThomas Gleixner 50356b3e64c2SThomas Gleixner seccomp 50366b3e64c2SThomas Gleixner - Same as "prctl" above, but all seccomp 50376b3e64c2SThomas Gleixner threads will enable the mitigation unless 50386b3e64c2SThomas Gleixner they explicitly opt out. 50396b3e64c2SThomas Gleixner 504055a97402SThomas Gleixner seccomp,ibpb 504155a97402SThomas Gleixner - Like "seccomp" above, but only STIBP is 504255a97402SThomas Gleixner controlled per thread. IBPB is issued 504355a97402SThomas Gleixner always when switching between different 504455a97402SThomas Gleixner user space processes. 504555a97402SThomas Gleixner 5046fa1202efSThomas Gleixner auto - Kernel selects the mitigation depending on 5047fa1202efSThomas Gleixner the available CPU features and vulnerability. 50486b3e64c2SThomas Gleixner 50496b3e64c2SThomas Gleixner Default mitigation: 50506b3e64c2SThomas Gleixner If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl" 5051fa1202efSThomas Gleixner 5052fa1202efSThomas Gleixner Not specifying this option is equivalent to 5053fa1202efSThomas Gleixner spectre_v2_user=auto. 5054fa1202efSThomas Gleixner 505524f7fc83SKonrad Rzeszutek Wilk spec_store_bypass_disable= 505624f7fc83SKonrad Rzeszutek Wilk [HW] Control Speculative Store Bypass (SSB) Disable mitigation 505724f7fc83SKonrad Rzeszutek Wilk (Speculative Store Bypass vulnerability) 505824f7fc83SKonrad Rzeszutek Wilk 505924f7fc83SKonrad Rzeszutek Wilk Certain CPUs are vulnerable to an exploit against a 506024f7fc83SKonrad Rzeszutek Wilk a common industry wide performance optimization known 506124f7fc83SKonrad Rzeszutek Wilk as "Speculative Store Bypass" in which recent stores 506224f7fc83SKonrad Rzeszutek Wilk to the same memory location may not be observed by 506324f7fc83SKonrad Rzeszutek Wilk later loads during speculative execution. The idea 506424f7fc83SKonrad Rzeszutek Wilk is that such stores are unlikely and that they can 506524f7fc83SKonrad Rzeszutek Wilk be detected prior to instruction retirement at the 506624f7fc83SKonrad Rzeszutek Wilk end of a particular speculation execution window. 506724f7fc83SKonrad Rzeszutek Wilk 506824f7fc83SKonrad Rzeszutek Wilk In vulnerable processors, the speculatively forwarded 506924f7fc83SKonrad Rzeszutek Wilk store can be used in a cache side channel attack, for 507024f7fc83SKonrad Rzeszutek Wilk example to read memory to which the attacker does not 507124f7fc83SKonrad Rzeszutek Wilk directly have access (e.g. inside sandboxed code). 507224f7fc83SKonrad Rzeszutek Wilk 507324f7fc83SKonrad Rzeszutek Wilk This parameter controls whether the Speculative Store 507424f7fc83SKonrad Rzeszutek Wilk Bypass optimization is used. 507524f7fc83SKonrad Rzeszutek Wilk 50766b4c1360SMichael Ellerman On x86 the options are: 50776b4c1360SMichael Ellerman 507824f7fc83SKonrad Rzeszutek Wilk on - Unconditionally disable Speculative Store Bypass 507924f7fc83SKonrad Rzeszutek Wilk off - Unconditionally enable Speculative Store Bypass 508024f7fc83SKonrad Rzeszutek Wilk auto - Kernel detects whether the CPU model contains an 508124f7fc83SKonrad Rzeszutek Wilk implementation of Speculative Store Bypass and 5082f21b53b2SKees Cook picks the most appropriate mitigation. If the 5083f21b53b2SKees Cook CPU is not vulnerable, "off" is selected. If the 5084f21b53b2SKees Cook CPU is vulnerable the default mitigation is 5085f21b53b2SKees Cook architecture and Kconfig dependent. See below. 5086a73ec77eSThomas Gleixner prctl - Control Speculative Store Bypass per thread 5087a73ec77eSThomas Gleixner via prctl. Speculative Store Bypass is enabled 5088a73ec77eSThomas Gleixner for a process by default. The state of the control 5089a73ec77eSThomas Gleixner is inherited on fork. 5090f21b53b2SKees Cook seccomp - Same as "prctl" above, but all seccomp threads 5091f21b53b2SKees Cook will disable SSB unless they explicitly opt out. 509224f7fc83SKonrad Rzeszutek Wilk 5093f21b53b2SKees Cook Default mitigations: 5094f21b53b2SKees Cook X86: If CONFIG_SECCOMP=y "seccomp", otherwise "prctl" 5095f21b53b2SKees Cook 50966b4c1360SMichael Ellerman On powerpc the options are: 50976b4c1360SMichael Ellerman 50986b4c1360SMichael Ellerman on,auto - On Power8 and Power9 insert a store-forwarding 50996b4c1360SMichael Ellerman barrier on kernel entry and exit. On Power7 51006b4c1360SMichael Ellerman perform a software flush on kernel entry and 51016b4c1360SMichael Ellerman exit. 51026b4c1360SMichael Ellerman off - No action. 51036b4c1360SMichael Ellerman 51046b4c1360SMichael Ellerman Not specifying this option is equivalent to 51056b4c1360SMichael Ellerman spec_store_bypass_disable=auto. 51066b4c1360SMichael Ellerman 5107e52347bdSJani Nikula spia_io_base= [HW,MTD] 5108e52347bdSJani Nikula spia_fio_base= 5109e52347bdSJani Nikula spia_pedr= 5110e52347bdSJani Nikula spia_peddr= 5111e52347bdSJani Nikula 51126650cdd9SPeter Zijlstra (Intel) split_lock_detect= 51136650cdd9SPeter Zijlstra (Intel) [X86] Enable split lock detection 51146650cdd9SPeter Zijlstra (Intel) 51156650cdd9SPeter Zijlstra (Intel) When enabled (and if hardware support is present), atomic 51166650cdd9SPeter Zijlstra (Intel) instructions that access data across cache line 51176650cdd9SPeter Zijlstra (Intel) boundaries will result in an alignment check exception. 51186650cdd9SPeter Zijlstra (Intel) 51196650cdd9SPeter Zijlstra (Intel) off - not enabled 51206650cdd9SPeter Zijlstra (Intel) 51216650cdd9SPeter Zijlstra (Intel) warn - the kernel will emit rate limited warnings 51226650cdd9SPeter Zijlstra (Intel) about applications triggering the #AC 51236650cdd9SPeter Zijlstra (Intel) exception. This mode is the default on CPUs 51246650cdd9SPeter Zijlstra (Intel) that supports split lock detection. 51256650cdd9SPeter Zijlstra (Intel) 51266650cdd9SPeter Zijlstra (Intel) fatal - the kernel will send SIGBUS to applications 51276650cdd9SPeter Zijlstra (Intel) that trigger the #AC exception. 51286650cdd9SPeter Zijlstra (Intel) 51296650cdd9SPeter Zijlstra (Intel) If an #AC exception is hit in the kernel or in 51306650cdd9SPeter Zijlstra (Intel) firmware (i.e. not while executing in user mode) 51316650cdd9SPeter Zijlstra (Intel) the kernel will oops in either "warn" or "fatal" 51326650cdd9SPeter Zijlstra (Intel) mode. 51336650cdd9SPeter Zijlstra (Intel) 51347e5b3c26SMark Gross srbds= [X86,INTEL] 51357e5b3c26SMark Gross Control the Special Register Buffer Data Sampling 51367e5b3c26SMark Gross (SRBDS) mitigation. 51377e5b3c26SMark Gross 51387e5b3c26SMark Gross Certain CPUs are vulnerable to an MDS-like 51397e5b3c26SMark Gross exploit which can leak bits from the random 51407e5b3c26SMark Gross number generator. 51417e5b3c26SMark Gross 51427e5b3c26SMark Gross By default, this issue is mitigated by 51437e5b3c26SMark Gross microcode. However, the microcode fix can cause 51447e5b3c26SMark Gross the RDRAND and RDSEED instructions to become 51457e5b3c26SMark Gross much slower. Among other effects, this will 51467e5b3c26SMark Gross result in reduced throughput from /dev/urandom. 51477e5b3c26SMark Gross 51487e5b3c26SMark Gross The microcode mitigation can be disabled with 51497e5b3c26SMark Gross the following option: 51507e5b3c26SMark Gross 51517e5b3c26SMark Gross off: Disable mitigation and remove 51527e5b3c26SMark Gross performance impact to RDRAND and RDSEED 51537e5b3c26SMark Gross 5154c350c008SPaul E. McKenney srcutree.counter_wrap_check [KNL] 5155c350c008SPaul E. McKenney Specifies how frequently to check for 5156c350c008SPaul E. McKenney grace-period sequence counter wrap for the 5157c350c008SPaul E. McKenney srcu_data structure's ->srcu_gp_seq_needed field. 5158c350c008SPaul E. McKenney The greater the number of bits set in this kernel 5159c350c008SPaul E. McKenney parameter, the less frequently counter wrap will 5160c350c008SPaul E. McKenney be checked for. Note that the bottom two bits 5161c350c008SPaul E. McKenney are ignored. 5162c350c008SPaul E. McKenney 516322607d66SPaul E. McKenney srcutree.exp_holdoff [KNL] 516422607d66SPaul E. McKenney Specifies how many nanoseconds must elapse 516522607d66SPaul E. McKenney since the end of the last SRCU grace period for 516622607d66SPaul E. McKenney a given srcu_struct until the next normal SRCU 516722607d66SPaul E. McKenney grace period will be considered for automatic 516822607d66SPaul E. McKenney expediting. Set to zero to disable automatic 516922607d66SPaul E. McKenney expediting. 517022607d66SPaul E. McKenney 5171a43ae4dfSMarc Zyngier ssbd= [ARM64,HW] 5172a43ae4dfSMarc Zyngier Speculative Store Bypass Disable control 5173a43ae4dfSMarc Zyngier 5174a43ae4dfSMarc Zyngier On CPUs that are vulnerable to the Speculative 5175a43ae4dfSMarc Zyngier Store Bypass vulnerability and offer a 5176a43ae4dfSMarc Zyngier firmware based mitigation, this parameter 5177a43ae4dfSMarc Zyngier indicates how the mitigation should be used: 5178a43ae4dfSMarc Zyngier 5179a43ae4dfSMarc Zyngier force-on: Unconditionally enable mitigation for 5180a43ae4dfSMarc Zyngier for both kernel and userspace 5181a43ae4dfSMarc Zyngier force-off: Unconditionally disable mitigation for 5182a43ae4dfSMarc Zyngier for both kernel and userspace 5183a43ae4dfSMarc Zyngier kernel: Always enable mitigation in the 5184a43ae4dfSMarc Zyngier kernel, and offer a prctl interface 5185a43ae4dfSMarc Zyngier to allow userspace to register its 5186a43ae4dfSMarc Zyngier interest in being mitigated too. 5187a43ae4dfSMarc Zyngier 51881be7107fSHugh Dickins stack_guard_gap= [MM] 51891be7107fSHugh Dickins override the default stack gap protection. The value 51901be7107fSHugh Dickins is in page units and it defines how many pages prior 51911be7107fSHugh Dickins to (for stacks growing down) resp. after (for stacks 51921be7107fSHugh Dickins growing up) the main stack are reserved for no other 51931be7107fSHugh Dickins mapping. Default value is 256 pages. 51941be7107fSHugh Dickins 5195e1fdc403SVijayanand Jitta stack_depot_disable= [KNL] 5196e1fdc403SVijayanand Jitta Setting this to true through kernel command line will 5197e1fdc403SVijayanand Jitta disable the stack depot thereby saving the static memory 5198e1fdc403SVijayanand Jitta consumed by the stack hash table. By default this is set 5199e1fdc403SVijayanand Jitta to false. 5200e1fdc403SVijayanand Jitta 5201e52347bdSJani Nikula stacktrace [FTRACE] 5202e52347bdSJani Nikula Enabled the stack tracer on boot up. 5203e52347bdSJani Nikula 5204e52347bdSJani Nikula stacktrace_filter=[function-list] 5205e52347bdSJani Nikula [FTRACE] Limit the functions that the stack tracer 520625942e5eSRandy Dunlap will trace at boot up. function-list is a comma-separated 5207e52347bdSJani Nikula list of functions. This list can be changed at run 5208e52347bdSJani Nikula time by the stack_trace_filter file in the debugfs 5209e52347bdSJani Nikula tracing directory. Note, this enables stack tracing 5210e52347bdSJani Nikula and the stacktrace above is not needed. 5211e52347bdSJani Nikula 5212e52347bdSJani Nikula sti= [PARISC,HW] 5213e52347bdSJani Nikula Format: <num> 5214e52347bdSJani Nikula Set the STI (builtin display/keyboard on the HP-PARISC 5215e52347bdSJani Nikula machines) console (graphic card) which should be used 5216e52347bdSJani Nikula as the initial boot-console. 5217e52347bdSJani Nikula See also comment in drivers/video/console/sticore.c. 5218e52347bdSJani Nikula 5219e52347bdSJani Nikula sti_font= [HW] 5220e52347bdSJani Nikula See comment in drivers/video/console/sticore.c. 5221e52347bdSJani Nikula 5222e52347bdSJani Nikula stifb= [HW] 5223e52347bdSJani Nikula Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] 5224e52347bdSJani Nikula 5225e52347bdSJani Nikula sunrpc.min_resvport= 5226e52347bdSJani Nikula sunrpc.max_resvport= 5227e52347bdSJani Nikula [NFS,SUNRPC] 5228e52347bdSJani Nikula SunRPC servers often require that client requests 5229e52347bdSJani Nikula originate from a privileged port (i.e. a port in the 5230e52347bdSJani Nikula range 0 < portnr < 1024). 5231e52347bdSJani Nikula An administrator who wishes to reserve some of these 5232e52347bdSJani Nikula ports for other uses may adjust the range that the 5233e52347bdSJani Nikula kernel's sunrpc client considers to be privileged 5234e52347bdSJani Nikula using these two parameters to set the minimum and 5235e52347bdSJani Nikula maximum port values. 5236e52347bdSJani Nikula 5237e52347bdSJani Nikula sunrpc.svc_rpc_per_connection_limit= 5238e52347bdSJani Nikula [NFS,SUNRPC] 5239e52347bdSJani Nikula Limit the number of requests that the server will 5240e52347bdSJani Nikula process in parallel from a single connection. 5241e52347bdSJani Nikula The default value is 0 (no limit). 5242e52347bdSJani Nikula 5243e52347bdSJani Nikula sunrpc.pool_mode= 5244e52347bdSJani Nikula [NFS] 5245e52347bdSJani Nikula Control how the NFS server code allocates CPUs to 5246e52347bdSJani Nikula service thread pools. Depending on how many NICs 5247e52347bdSJani Nikula you have and where their interrupts are bound, this 5248e52347bdSJani Nikula option will affect which CPUs will do NFS serving. 5249e52347bdSJani Nikula Note: this parameter cannot be changed while the 5250e52347bdSJani Nikula NFS server is running. 5251e52347bdSJani Nikula 5252e52347bdSJani Nikula auto the server chooses an appropriate mode 5253e52347bdSJani Nikula automatically using heuristics 5254e52347bdSJani Nikula global a single global pool contains all CPUs 5255e52347bdSJani Nikula percpu one pool for each CPU 5256e52347bdSJani Nikula pernode one pool for each NUMA node (equivalent 5257e52347bdSJani Nikula to global on non-NUMA machines) 5258e52347bdSJani Nikula 5259e52347bdSJani Nikula sunrpc.tcp_slot_table_entries= 5260e52347bdSJani Nikula sunrpc.udp_slot_table_entries= 5261e52347bdSJani Nikula [NFS,SUNRPC] 5262e52347bdSJani Nikula Sets the upper limit on the number of simultaneous 5263e52347bdSJani Nikula RPC calls that can be sent from the client to a 5264e52347bdSJani Nikula server. Increasing these values may allow you to 5265e52347bdSJani Nikula improve throughput, but will also increase the 5266e52347bdSJani Nikula amount of memory reserved for use by the client. 5267e52347bdSJani Nikula 5268e52347bdSJani Nikula suspend.pm_test_delay= 5269e52347bdSJani Nikula [SUSPEND] 5270e52347bdSJani Nikula Sets the number of seconds to remain in a suspend test 5271e52347bdSJani Nikula mode before resuming the system (see 5272e52347bdSJani Nikula /sys/power/pm_test). Only available when CONFIG_PM_DEBUG 5273e52347bdSJani Nikula is set. Default value is 5. 5274e52347bdSJani Nikula 52756a9c930bSRam Pai svm= [PPC] 52766a9c930bSRam Pai Format: { on | off | y | n | 1 | 0 } 52776a9c930bSRam Pai This parameter controls use of the Protected 52786a9c930bSRam Pai Execution Facility on pSeries. 52796a9c930bSRam Pai 5280e52347bdSJani Nikula swapaccount=[0|1] 5281e52347bdSJani Nikula [KNL] Enable accounting of swap in memory resource 5282e52347bdSJani Nikula controller if no parameter or 1 is given or disable 5283da82c92fSMauro Carvalho Chehab it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst) 5284e52347bdSJani Nikula 5285e52347bdSJani Nikula swiotlb= [ARM,IA-64,PPC,MIPS,X86] 5286fff5d992SGeert Uytterhoeven Format: { <int> | force | noforce } 5287e52347bdSJani Nikula <int> -- Number of I/O TLB slabs 5288e52347bdSJani Nikula force -- force using of bounce buffers even if they 5289e52347bdSJani Nikula wouldn't be automatically used by the kernel 5290fff5d992SGeert Uytterhoeven noforce -- Never use bounce buffers (for debugging) 5291e52347bdSJani Nikula 5292e52347bdSJani Nikula switches= [HW,M68k] 5293e52347bdSJani Nikula 52943db978d4SVlastimil Babka sysctl.*= [KNL] 52953db978d4SVlastimil Babka Set a sysctl parameter, right before loading the init 52963db978d4SVlastimil Babka process, as if the value was written to the respective 52973db978d4SVlastimil Babka /proc/sys/... file. Both '.' and '/' are recognized as 52983db978d4SVlastimil Babka separators. Unrecognized parameters and invalid values 52993db978d4SVlastimil Babka are reported in the kernel log. Sysctls registered 53003db978d4SVlastimil Babka later by a loaded module cannot be set this way. 53013db978d4SVlastimil Babka Example: sysctl.vm.swappiness=40 53023db978d4SVlastimil Babka 5303e52347bdSJani Nikula sysfs.deprecated=0|1 [KNL] 5304e52347bdSJani Nikula Enable/disable old style sysfs layout for old udev 5305e52347bdSJani Nikula on older distributions. When this option is enabled 5306e52347bdSJani Nikula very new udev will not work anymore. When this option 5307e52347bdSJani Nikula is disabled (or CONFIG_SYSFS_DEPRECATED not compiled) 5308e52347bdSJani Nikula in older udev will not work anymore. 5309e52347bdSJani Nikula Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in 5310e52347bdSJani Nikula the kernel configuration. 5311e52347bdSJani Nikula 5312e52347bdSJani Nikula sysrq_always_enabled 5313e52347bdSJani Nikula [KNL] 5314e52347bdSJani Nikula Ignore sysrq setting - this boot parameter will 5315e52347bdSJani Nikula neutralize any effect of /proc/sys/kernel/sysrq. 5316e52347bdSJani Nikula Useful for debugging. 5317e52347bdSJani Nikula 5318e52347bdSJani Nikula tcpmhash_entries= [KNL,NET] 5319e52347bdSJani Nikula Set the number of tcp_metrics_hash slots. 5320e52347bdSJani Nikula Default value is 8192 or 16384 depending on total 5321e52347bdSJani Nikula ram pages. This is used to specify the TCP metrics 53221cec2cacSMauro Carvalho Chehab cache size. See Documentation/networking/ip-sysctl.rst 5323e52347bdSJani Nikula "tcp_no_metrics_save" section for more details. 5324e52347bdSJani Nikula 5325e52347bdSJani Nikula tdfx= [HW,DRM] 5326e52347bdSJani Nikula 5327e52347bdSJani Nikula test_suspend= [SUSPEND][,N] 5328e52347bdSJani Nikula Specify "mem" (for Suspend-to-RAM) or "standby" (for 5329e52347bdSJani Nikula standby suspend) or "freeze" (for suspend type freeze) 5330e52347bdSJani Nikula as the system sleep state during system startup with 5331e52347bdSJani Nikula the optional capability to repeat N number of times. 5332e52347bdSJani Nikula The system is woken from this state using a 5333e52347bdSJani Nikula wakeup-capable RTC alarm. 5334e52347bdSJani Nikula 5335e52347bdSJani Nikula thash_entries= [KNL,NET] 5336e52347bdSJani Nikula Set number of hash buckets for TCP connection 5337e52347bdSJani Nikula 5338e52347bdSJani Nikula thermal.act= [HW,ACPI] 5339e52347bdSJani Nikula -1: disable all active trip points in all thermal zones 5340e52347bdSJani Nikula <degrees C>: override all lowest active trip points 5341e52347bdSJani Nikula 5342e52347bdSJani Nikula thermal.crt= [HW,ACPI] 5343e52347bdSJani Nikula -1: disable all critical trip points in all thermal zones 5344e52347bdSJani Nikula <degrees C>: override all critical trip points 5345e52347bdSJani Nikula 5346e52347bdSJani Nikula thermal.nocrt= [HW,ACPI] 5347e52347bdSJani Nikula Set to disable actions on ACPI thermal zone 5348e52347bdSJani Nikula critical and hot trip points. 5349e52347bdSJani Nikula 5350e52347bdSJani Nikula thermal.off= [HW,ACPI] 5351e52347bdSJani Nikula 1: disable ACPI thermal control 5352e52347bdSJani Nikula 5353e52347bdSJani Nikula thermal.psv= [HW,ACPI] 5354e52347bdSJani Nikula -1: disable all passive trip points 5355e52347bdSJani Nikula <degrees C>: override all passive trip points to this 5356e52347bdSJani Nikula value 5357e52347bdSJani Nikula 5358e52347bdSJani Nikula thermal.tzp= [HW,ACPI] 5359e52347bdSJani Nikula Specify global default ACPI thermal zone polling rate 5360e52347bdSJani Nikula <deci-seconds>: poll all this frequency 5361e52347bdSJani Nikula 0: no polling (default) 5362e52347bdSJani Nikula 5363e52347bdSJani Nikula threadirqs [KNL] 5364e52347bdSJani Nikula Force threading of all interrupt handlers except those 5365e52347bdSJani Nikula marked explicitly IRQF_NO_THREAD. 5366e52347bdSJani Nikula 5367e52347bdSJani Nikula topology= [S390] 5368e52347bdSJani Nikula Format: {off | on} 5369e52347bdSJani Nikula Specify if the kernel should make use of the cpu 5370e52347bdSJani Nikula topology information if the hardware supports this. 5371e52347bdSJani Nikula The scheduler will make use of this information and 5372e52347bdSJani Nikula e.g. base its process migration decisions on it. 5373e52347bdSJani Nikula Default is on. 5374e52347bdSJani Nikula 5375e52347bdSJani Nikula topology_updates= [KNL, PPC, NUMA] 5376e52347bdSJani Nikula Format: {off} 5377e52347bdSJani Nikula Specify if the kernel should ignore (off) 5378e52347bdSJani Nikula topology updates sent by the hypervisor to this 5379e52347bdSJani Nikula LPAR. 5380e52347bdSJani Nikula 53818171d3e0SPaul E. McKenney torture.disable_onoff_at_boot= [KNL] 53828171d3e0SPaul E. McKenney Prevent the CPU-hotplug component of torturing 53838171d3e0SPaul E. McKenney until after init has spawned. 53848171d3e0SPaul E. McKenney 53852102ad29SPaul E. McKenney torture.ftrace_dump_at_shutdown= [KNL] 53862102ad29SPaul E. McKenney Dump the ftrace buffer at torture-test shutdown, 53872102ad29SPaul E. McKenney even if there were no errors. This can be a 53882102ad29SPaul E. McKenney very costly operation when many torture tests 53892102ad29SPaul E. McKenney are running concurrently, especially on systems 53902102ad29SPaul E. McKenney with rotating-rust storage. 53912102ad29SPaul E. McKenney 53928a67a20bSPaul E. McKenney torture.verbose_sleep_frequency= [KNL] 53938a67a20bSPaul E. McKenney Specifies how many verbose printk()s should be 53948a67a20bSPaul E. McKenney emitted between each sleep. The default of zero 53958a67a20bSPaul E. McKenney disables verbose-printk() sleeping. 53968a67a20bSPaul E. McKenney 53978a67a20bSPaul E. McKenney torture.verbose_sleep_duration= [KNL] 53988a67a20bSPaul E. McKenney Duration of each verbose-printk() sleep in jiffies. 53998a67a20bSPaul E. McKenney 5400e52347bdSJani Nikula tp720= [HW,PS2] 5401e52347bdSJani Nikula 5402e52347bdSJani Nikula tpm_suspend_pcr=[HW,TPM] 5403e52347bdSJani Nikula Format: integer pcr id 5404e52347bdSJani Nikula Specify that at suspend time, the tpm driver 5405e52347bdSJani Nikula should extend the specified pcr with zeros, 5406e52347bdSJani Nikula as a workaround for some chips which fail to 5407e52347bdSJani Nikula flush the last written pcr on TPM_SaveState. 5408e52347bdSJani Nikula This will guarantee that all the other pcrs 5409e52347bdSJani Nikula are saved. 5410e52347bdSJani Nikula 5411e52347bdSJani Nikula trace_buf_size=nn[KMG] 5412e52347bdSJani Nikula [FTRACE] will set tracing buffer size on each cpu. 5413e52347bdSJani Nikula 5414e52347bdSJani Nikula trace_event=[event-list] 5415e52347bdSJani Nikula [FTRACE] Set and start specified trace events in order 5416e52347bdSJani Nikula to facilitate early boot debugging. The event-list is a 541725942e5eSRandy Dunlap comma-separated list of trace events to enable. See 54185fb94e9cSMauro Carvalho Chehab also Documentation/trace/events.rst 5419e52347bdSJani Nikula 5420e52347bdSJani Nikula trace_options=[option-list] 5421e52347bdSJani Nikula [FTRACE] Enable or disable tracer options at boot. 5422e52347bdSJani Nikula The option-list is a comma delimited list of options 5423e52347bdSJani Nikula that can be enabled or disabled just as if you were 5424e52347bdSJani Nikula to echo the option name into 5425e52347bdSJani Nikula 5426e52347bdSJani Nikula /sys/kernel/debug/tracing/trace_options 5427e52347bdSJani Nikula 5428e52347bdSJani Nikula For example, to enable stacktrace option (to dump the 5429e52347bdSJani Nikula stack trace of each event), add to the command line: 5430e52347bdSJani Nikula 5431e52347bdSJani Nikula trace_options=stacktrace 5432e52347bdSJani Nikula 54335fb94e9cSMauro Carvalho Chehab See also Documentation/trace/ftrace.rst "trace options" 5434e52347bdSJani Nikula section. 5435e52347bdSJani Nikula 5436e52347bdSJani Nikula tp_printk[FTRACE] 5437e52347bdSJani Nikula Have the tracepoints sent to printk as well as the 5438e52347bdSJani Nikula tracing ring buffer. This is useful for early boot up 5439e52347bdSJani Nikula where the system hangs or reboots and does not give the 5440e52347bdSJani Nikula option for reading the tracing buffer or performing a 5441e52347bdSJani Nikula ftrace_dump_on_oops. 5442e52347bdSJani Nikula 5443e52347bdSJani Nikula To turn off having tracepoints sent to printk, 5444e52347bdSJani Nikula echo 0 > /proc/sys/kernel/tracepoint_printk 5445e52347bdSJani Nikula Note, echoing 1 into this file without the 5446e52347bdSJani Nikula tracepoint_printk kernel cmdline option has no effect. 5447e52347bdSJani Nikula 5448e52347bdSJani Nikula ** CAUTION ** 5449e52347bdSJani Nikula 5450e52347bdSJani Nikula Having tracepoints sent to printk() and activating high 5451e52347bdSJani Nikula frequency tracepoints such as irq or sched, can cause 5452e52347bdSJani Nikula the system to live lock. 5453e52347bdSJani Nikula 5454e52347bdSJani Nikula traceoff_on_warning 5455e52347bdSJani Nikula [FTRACE] enable this option to disable tracing when a 5456e52347bdSJani Nikula warning is hit. This turns off "tracing_on". Tracing can 5457e52347bdSJani Nikula be enabled again by echoing '1' into the "tracing_on" 5458e52347bdSJani Nikula file located in /sys/kernel/debug/tracing/ 5459e52347bdSJani Nikula 5460e52347bdSJani Nikula This option is useful, as it disables the trace before 5461e52347bdSJani Nikula the WARNING dump is called, which prevents the trace to 5462e52347bdSJani Nikula be filled with content caused by the warning output. 5463e52347bdSJani Nikula 5464e52347bdSJani Nikula This option can also be set at run time via the sysctl 5465e52347bdSJani Nikula option: kernel/traceoff_on_warning 5466e52347bdSJani Nikula 5467e52347bdSJani Nikula transparent_hugepage= 5468e52347bdSJani Nikula [KNL] 5469e52347bdSJani Nikula Format: [always|madvise|never] 5470e52347bdSJani Nikula Can be used to control the default behavior of the system 5471e52347bdSJani Nikula with respect to transparent hugepages. 547245c9a74fSMike Rapoport See Documentation/admin-guide/mm/transhuge.rst 547345c9a74fSMike Rapoport for more details. 5474e52347bdSJani Nikula 5475e52347bdSJani Nikula tsc= Disable clocksource stability checks for TSC. 5476e52347bdSJani Nikula Format: <string> 5477e52347bdSJani Nikula [x86] reliable: mark tsc clocksource as reliable, this 5478e52347bdSJani Nikula disables clocksource verification at runtime, as well 5479e52347bdSJani Nikula as the stability checks done at bootup. Used to enable 5480e52347bdSJani Nikula high-resolution timer mode on older hardware, and in 5481e52347bdSJani Nikula virtualized environment. 5482e52347bdSJani Nikula [x86] noirqtime: Do not use TSC to do irq accounting. 5483e52347bdSJani Nikula Used to run time disable IRQ_TIME_ACCOUNTING on any 5484e52347bdSJani Nikula platforms where RDTSC is slow and this accounting 5485e52347bdSJani Nikula can add overhead. 54866be53520SDou Liyang [x86] unstable: mark the TSC clocksource as unstable, this 54876be53520SDou Liyang marks the TSC unconditionally unstable at bootup and 54886be53520SDou Liyang avoids any further wobbles once the TSC watchdog notices. 54890f0b7e1cSJuri Lelli [x86] nowatchdog: disable clocksource watchdog. Used 54900f0b7e1cSJuri Lelli in situations with strict latency requirements (where 54910f0b7e1cSJuri Lelli interruptions from clocksource watchdog are not 54920f0b7e1cSJuri Lelli acceptable). 5493e52347bdSJani Nikula 5494bd35c77eSKrzysztof Piecuch tsc_early_khz= [X86] Skip early TSC calibration and use the given 5495bd35c77eSKrzysztof Piecuch value instead. Useful when the early TSC frequency discovery 5496bd35c77eSKrzysztof Piecuch procedure is not reliable, such as on overclocked systems 5497bd35c77eSKrzysztof Piecuch with CPUID.16h support and partial CPUID.15h support. 5498bd35c77eSKrzysztof Piecuch Format: <unsigned int> 5499bd35c77eSKrzysztof Piecuch 550095c5824fSPawan Gupta tsx= [X86] Control Transactional Synchronization 550195c5824fSPawan Gupta Extensions (TSX) feature in Intel processors that 550295c5824fSPawan Gupta support TSX control. 550395c5824fSPawan Gupta 550495c5824fSPawan Gupta This parameter controls the TSX feature. The options are: 550595c5824fSPawan Gupta 550695c5824fSPawan Gupta on - Enable TSX on the system. Although there are 550795c5824fSPawan Gupta mitigations for all known security vulnerabilities, 550895c5824fSPawan Gupta TSX has been known to be an accelerator for 550995c5824fSPawan Gupta several previous speculation-related CVEs, and 551095c5824fSPawan Gupta so there may be unknown security risks associated 551195c5824fSPawan Gupta with leaving it enabled. 551295c5824fSPawan Gupta 551395c5824fSPawan Gupta off - Disable TSX on the system. (Note that this 551495c5824fSPawan Gupta option takes effect only on newer CPUs which are 551595c5824fSPawan Gupta not vulnerable to MDS, i.e., have 551695c5824fSPawan Gupta MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1 and which get 551795c5824fSPawan Gupta the new IA32_TSX_CTRL MSR through a microcode 551895c5824fSPawan Gupta update. This new MSR allows for the reliable 551995c5824fSPawan Gupta deactivation of the TSX functionality.) 552095c5824fSPawan Gupta 55217531a359SPawan Gupta auto - Disable TSX if X86_BUG_TAA is present, 55227531a359SPawan Gupta otherwise enable TSX on the system. 55237531a359SPawan Gupta 552495c5824fSPawan Gupta Not specifying this option is equivalent to tsx=off. 552595c5824fSPawan Gupta 552695c5824fSPawan Gupta See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst 552795c5824fSPawan Gupta for more details. 552895c5824fSPawan Gupta 5529a7a248c5SPawan Gupta tsx_async_abort= [X86,INTEL] Control mitigation for the TSX Async 5530a7a248c5SPawan Gupta Abort (TAA) vulnerability. 5531a7a248c5SPawan Gupta 5532a7a248c5SPawan Gupta Similar to Micro-architectural Data Sampling (MDS) 5533a7a248c5SPawan Gupta certain CPUs that support Transactional 5534a7a248c5SPawan Gupta Synchronization Extensions (TSX) are vulnerable to an 5535a7a248c5SPawan Gupta exploit against CPU internal buffers which can forward 5536a7a248c5SPawan Gupta information to a disclosure gadget under certain 5537a7a248c5SPawan Gupta conditions. 5538a7a248c5SPawan Gupta 5539a7a248c5SPawan Gupta In vulnerable processors, the speculatively forwarded 5540a7a248c5SPawan Gupta data can be used in a cache side channel attack, to 5541a7a248c5SPawan Gupta access data to which the attacker does not have direct 5542a7a248c5SPawan Gupta access. 5543a7a248c5SPawan Gupta 5544a7a248c5SPawan Gupta This parameter controls the TAA mitigation. The 5545a7a248c5SPawan Gupta options are: 5546a7a248c5SPawan Gupta 5547a7a248c5SPawan Gupta full - Enable TAA mitigation on vulnerable CPUs 5548a7a248c5SPawan Gupta if TSX is enabled. 5549a7a248c5SPawan Gupta 5550a7a248c5SPawan Gupta full,nosmt - Enable TAA mitigation and disable SMT on 5551a7a248c5SPawan Gupta vulnerable CPUs. If TSX is disabled, SMT 5552a7a248c5SPawan Gupta is not disabled because CPU is not 5553a7a248c5SPawan Gupta vulnerable to cross-thread TAA attacks. 5554a7a248c5SPawan Gupta off - Unconditionally disable TAA mitigation 5555a7a248c5SPawan Gupta 555664870ed1SWaiman Long On MDS-affected machines, tsx_async_abort=off can be 555764870ed1SWaiman Long prevented by an active MDS mitigation as both vulnerabilities 555864870ed1SWaiman Long are mitigated with the same mechanism so in order to disable 555964870ed1SWaiman Long this mitigation, you need to specify mds=off too. 556064870ed1SWaiman Long 5561a7a248c5SPawan Gupta Not specifying this option is equivalent to 5562a7a248c5SPawan Gupta tsx_async_abort=full. On CPUs which are MDS affected 5563a7a248c5SPawan Gupta and deploy MDS mitigation, TAA mitigation is not 5564a7a248c5SPawan Gupta required and doesn't provide any additional 5565a7a248c5SPawan Gupta mitigation. 5566a7a248c5SPawan Gupta 5567a7a248c5SPawan Gupta For details see: 5568a7a248c5SPawan Gupta Documentation/admin-guide/hw-vuln/tsx_async_abort.rst 5569a7a248c5SPawan Gupta 5570e52347bdSJani Nikula turbografx.map[2|3]= [HW,JOY] 5571e52347bdSJani Nikula TurboGraFX parallel port interface 5572e52347bdSJani Nikula Format: 5573e52347bdSJani Nikula <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> 55741752118dSTom Saeger See also Documentation/input/devices/joystick-parport.rst 5575e52347bdSJani Nikula 5576e52347bdSJani Nikula udbg-immortal [PPC] When debugging early kernel crashes that 5577e52347bdSJani Nikula happen after console_init() and before a proper 5578e52347bdSJani Nikula console driver takes over, this boot options might 5579e52347bdSJani Nikula help "seeing" what's going on. 5580e52347bdSJani Nikula 5581e52347bdSJani Nikula uhash_entries= [KNL,NET] 5582e52347bdSJani Nikula Set number of hash buckets for UDP/UDP-Lite connections 5583e52347bdSJani Nikula 5584e52347bdSJani Nikula uhci-hcd.ignore_oc= 5585e52347bdSJani Nikula [USB] Ignore overcurrent events (default N). 5586e52347bdSJani Nikula Some badly-designed motherboards generate lots of 5587e52347bdSJani Nikula bogus events, for ports that aren't wired to 5588e52347bdSJani Nikula anything. Set this parameter to avoid log spamming. 5589e52347bdSJani Nikula Note that genuine overcurrent events won't be 5590e52347bdSJani Nikula reported either. 5591e52347bdSJani Nikula 5592e52347bdSJani Nikula unknown_nmi_panic 5593e52347bdSJani Nikula [X86] Cause panic on unknown NMI. 5594e52347bdSJani Nikula 5595e52347bdSJani Nikula usbcore.authorized_default= 5596e52347bdSJani Nikula [USB] Default USB device authorization: 5597e52347bdSJani Nikula (default -1 = authorized except for wireless USB, 55987bae0432SDmitry Torokhov 0 = not authorized, 1 = authorized, 2 = authorized 55997bae0432SDmitry Torokhov if device connected to internal port) 5600e52347bdSJani Nikula 5601e52347bdSJani Nikula usbcore.autosuspend= 5602e52347bdSJani Nikula [USB] The autosuspend time delay (in seconds) used 5603e52347bdSJani Nikula for newly-detected USB devices (default 2). This 5604e52347bdSJani Nikula is the time required before an idle device will be 5605e52347bdSJani Nikula autosuspended. Devices for which the delay is set 5606e52347bdSJani Nikula to a negative value won't be autosuspended at all. 5607e52347bdSJani Nikula 5608e52347bdSJani Nikula usbcore.usbfs_snoop= 5609e52347bdSJani Nikula [USB] Set to log all usbfs traffic (default 0 = off). 5610e52347bdSJani Nikula 5611e52347bdSJani Nikula usbcore.usbfs_snoop_max= 5612e52347bdSJani Nikula [USB] Maximum number of bytes to snoop in each URB 5613e52347bdSJani Nikula (default = 65536). 5614e52347bdSJani Nikula 5615e52347bdSJani Nikula usbcore.blinkenlights= 5616e52347bdSJani Nikula [USB] Set to cycle leds on hubs (default 0 = off). 5617e52347bdSJani Nikula 5618e52347bdSJani Nikula usbcore.old_scheme_first= 5619e52347bdSJani Nikula [USB] Start with the old device initialization 56203155f4f4SAlan Stern scheme (default 0 = off). 5621e52347bdSJani Nikula 5622e52347bdSJani Nikula usbcore.usbfs_memory_mb= 5623e52347bdSJani Nikula [USB] Memory limit (in MB) for buffers allocated by 5624e52347bdSJani Nikula usbfs (default = 16, 0 = max = 2047). 5625e52347bdSJani Nikula 5626e52347bdSJani Nikula usbcore.use_both_schemes= 5627e52347bdSJani Nikula [USB] Try the other device initialization scheme 5628e52347bdSJani Nikula if the first one fails (default 1 = enabled). 5629e52347bdSJani Nikula 5630e52347bdSJani Nikula usbcore.initial_descriptor_timeout= 5631e52347bdSJani Nikula [USB] Specifies timeout for the initial 64-byte 5632e52347bdSJani Nikula USB_REQ_GET_DESCRIPTOR request in milliseconds 5633e52347bdSJani Nikula (default 5000 = 5.0 seconds). 5634e52347bdSJani Nikula 5635e52347bdSJani Nikula usbcore.nousb [USB] Disable the USB subsystem 5636e52347bdSJani Nikula 5637027bd6caSKai-Heng Feng usbcore.quirks= 5638027bd6caSKai-Heng Feng [USB] A list of quirk entries to augment the built-in 5639027bd6caSKai-Heng Feng usb core quirk list. List entries are separated by 5640027bd6caSKai-Heng Feng commas. Each entry has the form 5641027bd6caSKai-Heng Feng VendorID:ProductID:Flags. The IDs are 4-digit hex 5642027bd6caSKai-Heng Feng numbers and Flags is a set of letters. Each letter 5643027bd6caSKai-Heng Feng will change the built-in quirk; setting it if it is 5644027bd6caSKai-Heng Feng clear and clearing it if it is set. The letters have 5645027bd6caSKai-Heng Feng the following meanings: 5646027bd6caSKai-Heng Feng a = USB_QUIRK_STRING_FETCH_255 (string 5647027bd6caSKai-Heng Feng descriptors must not be fetched using 5648027bd6caSKai-Heng Feng a 255-byte read); 5649027bd6caSKai-Heng Feng b = USB_QUIRK_RESET_RESUME (device can't resume 5650027bd6caSKai-Heng Feng correctly so reset it instead); 5651027bd6caSKai-Heng Feng c = USB_QUIRK_NO_SET_INTF (device can't handle 5652027bd6caSKai-Heng Feng Set-Interface requests); 5653027bd6caSKai-Heng Feng d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't 5654027bd6caSKai-Heng Feng handle its Configuration or Interface 5655027bd6caSKai-Heng Feng strings); 5656027bd6caSKai-Heng Feng e = USB_QUIRK_RESET (device can't be reset 5657027bd6caSKai-Heng Feng (e.g morph devices), don't use reset); 5658027bd6caSKai-Heng Feng f = USB_QUIRK_HONOR_BNUMINTERFACES (device has 5659027bd6caSKai-Heng Feng more interface descriptions than the 5660027bd6caSKai-Heng Feng bNumInterfaces count, and can't handle 5661027bd6caSKai-Heng Feng talking to these interfaces); 5662027bd6caSKai-Heng Feng g = USB_QUIRK_DELAY_INIT (device needs a pause 5663027bd6caSKai-Heng Feng during initialization, after we read 5664027bd6caSKai-Heng Feng the device descriptor); 5665027bd6caSKai-Heng Feng h = USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL (For 5666027bd6caSKai-Heng Feng high speed and super speed interrupt 5667027bd6caSKai-Heng Feng endpoints, the USB 2.0 and USB 3.0 spec 5668027bd6caSKai-Heng Feng require the interval in microframes (1 5669027bd6caSKai-Heng Feng microframe = 125 microseconds) to be 5670027bd6caSKai-Heng Feng calculated as interval = 2 ^ 5671027bd6caSKai-Heng Feng (bInterval-1). 5672027bd6caSKai-Heng Feng Devices with this quirk report their 5673027bd6caSKai-Heng Feng bInterval as the result of this 5674027bd6caSKai-Heng Feng calculation instead of the exponent 5675027bd6caSKai-Heng Feng variable used in the calculation); 5676027bd6caSKai-Heng Feng i = USB_QUIRK_DEVICE_QUALIFIER (device can't 5677027bd6caSKai-Heng Feng handle device_qualifier descriptor 5678027bd6caSKai-Heng Feng requests); 5679027bd6caSKai-Heng Feng j = USB_QUIRK_IGNORE_REMOTE_WAKEUP (device 5680027bd6caSKai-Heng Feng generates spurious wakeup, ignore 5681027bd6caSKai-Heng Feng remote wakeup capability); 5682027bd6caSKai-Heng Feng k = USB_QUIRK_NO_LPM (device can't handle Link 5683027bd6caSKai-Heng Feng Power Management); 5684027bd6caSKai-Heng Feng l = USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL 5685027bd6caSKai-Heng Feng (Device reports its bInterval as linear 5686027bd6caSKai-Heng Feng frames instead of the USB 2.0 5687027bd6caSKai-Heng Feng calculation); 5688027bd6caSKai-Heng Feng m = USB_QUIRK_DISCONNECT_SUSPEND (Device needs 5689027bd6caSKai-Heng Feng to be disconnected before suspend to 56904d8d5a39SKai-Heng Feng prevent spurious wakeup); 56914d8d5a39SKai-Heng Feng n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a 56924d8d5a39SKai-Heng Feng pause after every control message); 5693781f0766SKai-Heng Feng o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra 5694781f0766SKai-Heng Feng delay after resetting its port); 5695027bd6caSKai-Heng Feng Example: quirks=0781:5580:bk,0a5c:5834:gij 5696027bd6caSKai-Heng Feng 5697e52347bdSJani Nikula usbhid.mousepoll= 5698e52347bdSJani Nikula [USBHID] The interval which mice are to be polled at. 5699e52347bdSJani Nikula 5700933bfe4dSTobias Jakobi usbhid.jspoll= 5701933bfe4dSTobias Jakobi [USBHID] The interval which joysticks are to be polled at. 5702933bfe4dSTobias Jakobi 57032ddc8e2dSFilip Alac usbhid.kbpoll= 57042ddc8e2dSFilip Alac [USBHID] The interval which keyboards are to be polled at. 57052ddc8e2dSFilip Alac 5706e52347bdSJani Nikula usb-storage.delay_use= 5707e52347bdSJani Nikula [UMS] The delay in seconds before a new device is 5708e52347bdSJani Nikula scanned for Logical Units (default 1). 5709e52347bdSJani Nikula 5710e52347bdSJani Nikula usb-storage.quirks= 5711e52347bdSJani Nikula [UMS] A list of quirks entries to supplement or 5712e52347bdSJani Nikula override the built-in unusual_devs list. List 5713e52347bdSJani Nikula entries are separated by commas. Each entry has 5714e52347bdSJani Nikula the form VID:PID:Flags where VID and PID are Vendor 5715e52347bdSJani Nikula and Product ID values (4-digit hex numbers) and 5716e52347bdSJani Nikula Flags is a set of characters, each corresponding 5717e52347bdSJani Nikula to a common usb-storage quirk flag as follows: 5718e52347bdSJani Nikula a = SANE_SENSE (collect more than 18 bytes 571965cc8bf9SOliver Neukum of sense data, not on uas); 5720e52347bdSJani Nikula b = BAD_SENSE (don't collect more than 18 572165cc8bf9SOliver Neukum bytes of sense data, not on uas); 5722e52347bdSJani Nikula c = FIX_CAPACITY (decrease the reported 5723e52347bdSJani Nikula device capacity by one sector); 5724e52347bdSJani Nikula d = NO_READ_DISC_INFO (don't use 572565cc8bf9SOliver Neukum READ_DISC_INFO command, not on uas); 5726e52347bdSJani Nikula e = NO_READ_CAPACITY_16 (don't use 5727e52347bdSJani Nikula READ_CAPACITY_16 command); 5728e52347bdSJani Nikula f = NO_REPORT_OPCODES (don't use report opcodes 5729e52347bdSJani Nikula command, uas only); 5730e52347bdSJani Nikula g = MAX_SECTORS_240 (don't transfer more than 5731e52347bdSJani Nikula 240 sectors at a time, uas only); 5732e52347bdSJani Nikula h = CAPACITY_HEURISTICS (decrease the 5733e52347bdSJani Nikula reported device capacity by one 5734e52347bdSJani Nikula sector if the number is odd); 5735e52347bdSJani Nikula i = IGNORE_DEVICE (don't bind to this 5736e52347bdSJani Nikula device); 5737e52347bdSJani Nikula j = NO_REPORT_LUNS (don't use report luns 5738e52347bdSJani Nikula command, uas only); 57398010622cSOliver Neukum k = NO_SAME (do not use WRITE_SAME, uas only) 5740e52347bdSJani Nikula l = NOT_LOCKABLE (don't try to lock and 574165cc8bf9SOliver Neukum unlock ejectable media, not on uas); 5742e52347bdSJani Nikula m = MAX_SECTORS_64 (don't transfer more 574365cc8bf9SOliver Neukum than 64 sectors = 32 KB at a time, 574465cc8bf9SOliver Neukum not on uas); 5745e52347bdSJani Nikula n = INITIAL_READ10 (force a retry of the 574665cc8bf9SOliver Neukum initial READ(10) command, not on uas); 5747e52347bdSJani Nikula o = CAPACITY_OK (accept the capacity 574865cc8bf9SOliver Neukum reported by the device, not on uas); 5749e52347bdSJani Nikula p = WRITE_CACHE (the device cache is ON 575065cc8bf9SOliver Neukum by default, not on uas); 5751e52347bdSJani Nikula r = IGNORE_RESIDUE (the device reports 575265cc8bf9SOliver Neukum bogus residue values, not on uas); 5753e52347bdSJani Nikula s = SINGLE_LUN (the device has only one 5754e52347bdSJani Nikula Logical Unit); 5755e52347bdSJani Nikula t = NO_ATA_1X (don't allow ATA(12) and ATA(16) 5756e52347bdSJani Nikula commands, uas only); 5757e52347bdSJani Nikula u = IGNORE_UAS (don't bind to the uas driver); 5758e52347bdSJani Nikula w = NO_WP_DETECT (don't test whether the 5759e52347bdSJani Nikula medium is write-protected). 5760e52347bdSJani Nikula y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE 576165cc8bf9SOliver Neukum even if the device claims no cache, 576265cc8bf9SOliver Neukum not on uas) 5763e52347bdSJani Nikula Example: quirks=0419:aaf5:rl,0421:0433:rc 5764e52347bdSJani Nikula 5765e52347bdSJani Nikula user_debug= [KNL,ARM] 5766e52347bdSJani Nikula Format: <int> 5767e52347bdSJani Nikula See arch/arm/Kconfig.debug help text. 5768e52347bdSJani Nikula 1 - undefined instruction events 5769e52347bdSJani Nikula 2 - system calls 5770e52347bdSJani Nikula 4 - invalid data aborts 5771e52347bdSJani Nikula 8 - SIGSEGV faults 5772e52347bdSJani Nikula 16 - SIGBUS faults 5773e52347bdSJani Nikula Example: user_debug=31 5774e52347bdSJani Nikula 5775e52347bdSJani Nikula userpte= 5776e52347bdSJani Nikula [X86] Flags controlling user PTE allocations. 5777e52347bdSJani Nikula 5778e52347bdSJani Nikula nohigh = do not allocate PTE pages in 5779e52347bdSJani Nikula HIGHMEM regardless of setting 5780e52347bdSJani Nikula of CONFIG_HIGHPTE. 5781e52347bdSJani Nikula 5782e52347bdSJani Nikula vdso= [X86,SH] 5783e52347bdSJani Nikula On X86_32, this is an alias for vdso32=. Otherwise: 5784e52347bdSJani Nikula 5785e52347bdSJani Nikula vdso=1: enable VDSO (the default) 5786e52347bdSJani Nikula vdso=0: disable VDSO mapping 5787e52347bdSJani Nikula 5788e52347bdSJani Nikula vdso32= [X86] Control the 32-bit vDSO 5789e52347bdSJani Nikula vdso32=1: enable 32-bit VDSO 5790e52347bdSJani Nikula vdso32=0 or vdso32=2: disable 32-bit VDSO 5791e52347bdSJani Nikula 5792e52347bdSJani Nikula See the help text for CONFIG_COMPAT_VDSO for more 5793e52347bdSJani Nikula details. If CONFIG_COMPAT_VDSO is set, the default is 5794e52347bdSJani Nikula vdso32=0; otherwise, the default is vdso32=1. 5795e52347bdSJani Nikula 5796e52347bdSJani Nikula For compatibility with older kernels, vdso32=2 is an 5797e52347bdSJani Nikula alias for vdso32=0. 5798e52347bdSJani Nikula 5799e52347bdSJani Nikula Try vdso32=0 if you encounter an error that says: 5800e52347bdSJani Nikula dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 5801e52347bdSJani Nikula 5802e52347bdSJani Nikula vector= [IA-64,SMP] 5803e52347bdSJani Nikula vector=percpu: enable percpu vector domain 5804e52347bdSJani Nikula 5805e52347bdSJani Nikula video= [FB] Frame buffer configuration 5806ab42b818SMauro Carvalho Chehab See Documentation/fb/modedb.rst. 5807e52347bdSJani Nikula 5808e52347bdSJani Nikula video.brightness_switch_enabled= [0,1] 5809e52347bdSJani Nikula If set to 1, on receiving an ACPI notify event 5810e52347bdSJani Nikula generated by hotkey, video driver will adjust brightness 5811e52347bdSJani Nikula level and then send out the event to user space through 5812e52347bdSJani Nikula the allocated input device; If set to 0, video driver 5813e52347bdSJani Nikula will only send out the event without touching backlight 5814e52347bdSJani Nikula brightness level. 5815e52347bdSJani Nikula default: 1 5816e52347bdSJani Nikula 5817e52347bdSJani Nikula virtio_mmio.device= 5818e52347bdSJani Nikula [VMMIO] Memory mapped virtio (platform) device. 5819e52347bdSJani Nikula 5820e52347bdSJani Nikula <size>@<baseaddr>:<irq>[:<id>] 5821e52347bdSJani Nikula where: 5822e52347bdSJani Nikula <size> := size (can use standard suffixes 5823e52347bdSJani Nikula like K, M and G) 5824e52347bdSJani Nikula <baseaddr> := physical base address 5825e52347bdSJani Nikula <irq> := interrupt number (as passed to 5826e52347bdSJani Nikula request_irq()) 5827e52347bdSJani Nikula <id> := (optional) platform device id 5828e52347bdSJani Nikula example: 5829e52347bdSJani Nikula virtio_mmio.device=1K@0x100b0000:48:7 5830e52347bdSJani Nikula 5831e52347bdSJani Nikula Can be used multiple times for multiple devices. 5832e52347bdSJani Nikula 5833e52347bdSJani Nikula vga= [BOOT,X86-32] Select a particular video mode 5834cb1aaebeSMauro Carvalho Chehab See Documentation/x86/boot.rst and 58354f4cfa6cSMauro Carvalho Chehab Documentation/admin-guide/svga.rst. 5836e52347bdSJani Nikula Use vga=ask for menu. 5837e52347bdSJani Nikula This is actually a boot loader parameter; the value is 5838e52347bdSJani Nikula passed to the kernel using a special protocol. 5839e52347bdSJani Nikula 5840f682a97aSAlexander Duyck vm_debug[=options] [KNL] Available with CONFIG_DEBUG_VM=y. 5841f682a97aSAlexander Duyck May slow down system boot speed, especially when 5842f682a97aSAlexander Duyck enabled on systems with a large amount of memory. 5843f682a97aSAlexander Duyck All options are enabled by default, and this 5844f682a97aSAlexander Duyck interface is meant to allow for selectively 5845f682a97aSAlexander Duyck enabling or disabling specific virtual memory 5846f682a97aSAlexander Duyck debugging features. 5847f682a97aSAlexander Duyck 5848f682a97aSAlexander Duyck Available options are: 5849f682a97aSAlexander Duyck P Enable page structure init time poisoning 5850f682a97aSAlexander Duyck - Disable all of the above options 5851f682a97aSAlexander Duyck 5852e52347bdSJani Nikula vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact 5853e52347bdSJani Nikula size of <nn>. This can be used to increase the 5854e52347bdSJani Nikula minimum size (128MB on x86). It can also be used to 5855e52347bdSJani Nikula decrease the size and leave more room for directly 5856e52347bdSJani Nikula mapped kernel RAM. 5857e52347bdSJani Nikula 58583f429842SHeiko Carstens vmcp_cma=nn[MG] [KNL,S390] 58593f429842SHeiko Carstens Sets the memory size reserved for contiguous memory 58603f429842SHeiko Carstens allocations for the vmcp device driver. 58613f429842SHeiko Carstens 5862e52347bdSJani Nikula vmhalt= [KNL,S390] Perform z/VM CP command after system halt. 5863e52347bdSJani Nikula Format: <command> 5864e52347bdSJani Nikula 5865e52347bdSJani Nikula vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. 5866e52347bdSJani Nikula Format: <command> 5867e52347bdSJani Nikula 5868e52347bdSJani Nikula vmpoff= [KNL,S390] Perform z/VM CP command after power off. 5869e52347bdSJani Nikula Format: <command> 5870e52347bdSJani Nikula 5871e52347bdSJani Nikula vsyscall= [X86-64] 5872e52347bdSJani Nikula Controls the behavior of vsyscalls (i.e. calls to 5873e52347bdSJani Nikula fixed addresses of 0xffffffffff600x00 from legacy 5874e52347bdSJani Nikula code). Most statically-linked binaries and older 5875e52347bdSJani Nikula versions of glibc use these calls. Because these 5876e52347bdSJani Nikula functions are at fixed addresses, they make nice 5877e52347bdSJani Nikula targets for exploits that can control RIP. 5878e52347bdSJani Nikula 5879e52347bdSJani Nikula emulate [default] Vsyscalls turn into traps and are 5880bd49e16eSAndy Lutomirski emulated reasonably safely. The vsyscall 5881bd49e16eSAndy Lutomirski page is readable. 5882e52347bdSJani Nikula 5883bd49e16eSAndy Lutomirski xonly Vsyscalls turn into traps and are 5884bd49e16eSAndy Lutomirski emulated reasonably safely. The vsyscall 5885bd49e16eSAndy Lutomirski page is not readable. 5886e52347bdSJani Nikula 5887e52347bdSJani Nikula none Vsyscalls don't work at all. This makes 5888e52347bdSJani Nikula them quite hard to use for exploits but 5889e52347bdSJani Nikula might break your system. 5890e52347bdSJani Nikula 5891e52347bdSJani Nikula vt.color= [VT] Default text color. 5892e52347bdSJani Nikula Format: 0xYX, X = foreground, Y = background. 5893e52347bdSJani Nikula Default: 0x07 = light gray on black. 5894e52347bdSJani Nikula 5895e52347bdSJani Nikula vt.cur_default= [VT] Default cursor shape. 5896e52347bdSJani Nikula Format: 0xCCBBAA, where AA, BB, and CC are the same as 5897e52347bdSJani Nikula the parameters of the <Esc>[?A;B;Cc escape sequence; 5898e52347bdSJani Nikula see VGA-softcursor.txt. Default: 2 = underline. 5899e52347bdSJani Nikula 5900e52347bdSJani Nikula vt.default_blu= [VT] 5901e52347bdSJani Nikula Format: <blue0>,<blue1>,<blue2>,...,<blue15> 5902e52347bdSJani Nikula Change the default blue palette of the console. 5903e52347bdSJani Nikula This is a 16-member array composed of values 5904e52347bdSJani Nikula ranging from 0-255. 5905e52347bdSJani Nikula 5906e52347bdSJani Nikula vt.default_grn= [VT] 5907e52347bdSJani Nikula Format: <green0>,<green1>,<green2>,...,<green15> 5908e52347bdSJani Nikula Change the default green palette of the console. 5909e52347bdSJani Nikula This is a 16-member array composed of values 5910e52347bdSJani Nikula ranging from 0-255. 5911e52347bdSJani Nikula 5912e52347bdSJani Nikula vt.default_red= [VT] 5913e52347bdSJani Nikula Format: <red0>,<red1>,<red2>,...,<red15> 5914e52347bdSJani Nikula Change the default red palette of the console. 5915e52347bdSJani Nikula This is a 16-member array composed of values 5916e52347bdSJani Nikula ranging from 0-255. 5917e52347bdSJani Nikula 5918e52347bdSJani Nikula vt.default_utf8= 5919e52347bdSJani Nikula [VT] 5920e52347bdSJani Nikula Format=<0|1> 5921e52347bdSJani Nikula Set system-wide default UTF-8 mode for all tty's. 5922e52347bdSJani Nikula Default is 1, i.e. UTF-8 mode is enabled for all 5923e52347bdSJani Nikula newly opened terminals. 5924e52347bdSJani Nikula 5925e52347bdSJani Nikula vt.global_cursor_default= 5926e52347bdSJani Nikula [VT] 5927e52347bdSJani Nikula Format=<-1|0|1> 5928e52347bdSJani Nikula Set system-wide default for whether a cursor 5929e52347bdSJani Nikula is shown on new VTs. Default is -1, 5930e52347bdSJani Nikula i.e. cursors will be created by default unless 5931e52347bdSJani Nikula overridden by individual drivers. 0 will hide 5932e52347bdSJani Nikula cursors, 1 will display them. 5933e52347bdSJani Nikula 5934e52347bdSJani Nikula vt.italic= [VT] Default color for italic text; 0-15. 5935e52347bdSJani Nikula Default: 2 = green. 5936e52347bdSJani Nikula 5937e52347bdSJani Nikula vt.underline= [VT] Default color for underlined text; 0-15. 5938e52347bdSJani Nikula Default: 3 = cyan. 5939e52347bdSJani Nikula 5940e52347bdSJani Nikula watchdog timers [HW,WDT] For information on watchdog timers, 5941cc2a2d19SMauro Carvalho Chehab see Documentation/watchdog/watchdog-parameters.rst 5942e52347bdSJani Nikula or other driver-specific files in the 5943e52347bdSJani Nikula Documentation/watchdog/ directory. 5944e52347bdSJani Nikula 594511295055SLaurence Oberman watchdog_thresh= 594611295055SLaurence Oberman [KNL] 594711295055SLaurence Oberman Set the hard lockup detector stall duration 594811295055SLaurence Oberman threshold in seconds. The soft lockup detector 594911295055SLaurence Oberman threshold is set to twice the value. A value of 0 595011295055SLaurence Oberman disables both lockup detectors. Default is 10 595111295055SLaurence Oberman seconds. 595211295055SLaurence Oberman 5953e52347bdSJani Nikula workqueue.watchdog_thresh= 5954e52347bdSJani Nikula If CONFIG_WQ_WATCHDOG is configured, workqueue can 5955e52347bdSJani Nikula warn stall conditions and dump internal state to 5956e52347bdSJani Nikula help debugging. 0 disables workqueue stall 5957e52347bdSJani Nikula detection; otherwise, it's the stall threshold 5958e52347bdSJani Nikula duration in seconds. The default value is 30 and 5959e52347bdSJani Nikula it can be updated at runtime by writing to the 5960e52347bdSJani Nikula corresponding sysfs file. 5961e52347bdSJani Nikula 5962e52347bdSJani Nikula workqueue.disable_numa 5963e52347bdSJani Nikula By default, all work items queued to unbound 5964e52347bdSJani Nikula workqueues are affine to the NUMA nodes they're 5965e52347bdSJani Nikula issued on, which results in better behavior in 5966e52347bdSJani Nikula general. If NUMA affinity needs to be disabled for 5967e52347bdSJani Nikula whatever reason, this option can be used. Note 5968e52347bdSJani Nikula that this also can be controlled per-workqueue for 5969e52347bdSJani Nikula workqueues visible under /sys/bus/workqueue/. 5970e52347bdSJani Nikula 5971e52347bdSJani Nikula workqueue.power_efficient 5972e52347bdSJani Nikula Per-cpu workqueues are generally preferred because 5973e52347bdSJani Nikula they show better performance thanks to cache 5974e52347bdSJani Nikula locality; unfortunately, per-cpu workqueues tend to 5975e52347bdSJani Nikula be more power hungry than unbound workqueues. 5976e52347bdSJani Nikula 5977e52347bdSJani Nikula Enabling this makes the per-cpu workqueues which 5978e52347bdSJani Nikula were observed to contribute significantly to power 5979e52347bdSJani Nikula consumption unbound, leading to measurably lower 5980e52347bdSJani Nikula power usage at the cost of small performance 5981e52347bdSJani Nikula overhead. 5982e52347bdSJani Nikula 5983e52347bdSJani Nikula The default value of this parameter is determined by 5984e52347bdSJani Nikula the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT. 5985e52347bdSJani Nikula 5986e52347bdSJani Nikula workqueue.debug_force_rr_cpu 5987e52347bdSJani Nikula Workqueue used to implicitly guarantee that work 5988e52347bdSJani Nikula items queued without explicit CPU specified are put 5989e52347bdSJani Nikula on the local CPU. This guarantee is no longer true 5990e52347bdSJani Nikula and while local CPU is still preferred work items 5991e52347bdSJani Nikula may be put on foreign CPUs. This debug option 5992e52347bdSJani Nikula forces round-robin CPU selection to flush out 5993e52347bdSJani Nikula usages which depend on the now broken guarantee. 5994e52347bdSJani Nikula When enabled, memory and cache locality will be 5995e52347bdSJani Nikula impacted. 5996e52347bdSJani Nikula 5997e52347bdSJani Nikula x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of 5998e52347bdSJani Nikula default x2apic cluster mode on platforms 5999e52347bdSJani Nikula supporting x2apic. 6000e52347bdSJani Nikula 6001e52347bdSJani Nikula xen_512gb_limit [KNL,X86-64,XEN] 6002e52347bdSJani Nikula Restricts the kernel running paravirtualized under Xen 6003e52347bdSJani Nikula to use only up to 512 GB of RAM. The reason to do so is 6004e52347bdSJani Nikula crash analysis tools and Xen tools for doing domain 6005e52347bdSJani Nikula save/restore/migration must be enabled to handle larger 6006e52347bdSJani Nikula domains. 6007e52347bdSJani Nikula 6008e52347bdSJani Nikula xen_emul_unplug= [HW,X86,XEN] 6009e52347bdSJani Nikula Unplug Xen emulated devices 6010e52347bdSJani Nikula Format: [unplug0,][unplug1] 6011e52347bdSJani Nikula ide-disks -- unplug primary master IDE devices 6012e52347bdSJani Nikula aux-ide-disks -- unplug non-primary-master IDE devices 6013e52347bdSJani Nikula nics -- unplug network devices 6014e52347bdSJani Nikula all -- unplug all emulated devices (NICs and IDE disks) 6015e52347bdSJani Nikula unnecessary -- unplugging emulated devices is 6016e52347bdSJani Nikula unnecessary even if the host did not respond to 6017e52347bdSJani Nikula the unplug protocol 6018e52347bdSJani Nikula never -- do not unplug even if version check succeeds 6019e52347bdSJani Nikula 6020c6875f3aSBoris Ostrovsky xen_legacy_crash [X86,XEN] 6021c6875f3aSBoris Ostrovsky Crash from Xen panic notifier, without executing late 6022c6875f3aSBoris Ostrovsky panic() code such as dumping handler. 6023c6875f3aSBoris Ostrovsky 6024e52347bdSJani Nikula xen_nopvspin [X86,XEN] 60259a3c05e6SZhenzhong Duan Disables the qspinlock slowpath using Xen PV optimizations. 60269a3c05e6SZhenzhong Duan This parameter is obsoleted by "nopvspin" parameter, which 60279a3c05e6SZhenzhong Duan has equivalent effect for XEN platform. 6028e52347bdSJani Nikula 6029e52347bdSJani Nikula xen_nopv [X86] 6030e52347bdSJani Nikula Disables the PV optimizations forcing the HVM guest to 6031e52347bdSJani Nikula run as generic HVM guest with no PV drivers. 6032b39b0497SZhenzhong Duan This option is obsoleted by the "nopv" option, which 6033b39b0497SZhenzhong Duan has equivalent effect for XEN platform. 6034e52347bdSJani Nikula 6035b36b0fe9SDavid Woodhouse xen_no_vector_callback 6036b36b0fe9SDavid Woodhouse [KNL,X86,XEN] Disable the vector callback for Xen 6037b36b0fe9SDavid Woodhouse event channel interrupts. 6038b36b0fe9SDavid Woodhouse 6039197ecb38SMarek Marczykowski-Górecki xen_scrub_pages= [XEN] 6040197ecb38SMarek Marczykowski-Górecki Boolean option to control scrubbing pages before giving them back 6041197ecb38SMarek Marczykowski-Górecki to Xen, for use by other domains. Can be also changed at runtime 6042197ecb38SMarek Marczykowski-Górecki with /sys/devices/system/xen_memory/xen_memory0/scrub_pages. 6043197ecb38SMarek Marczykowski-Górecki Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT. 6044197ecb38SMarek Marczykowski-Górecki 60452ec16bc0SRyan Thibodeaux xen_timer_slop= [X86-64,XEN] 60462ec16bc0SRyan Thibodeaux Set the timer slop (in nanoseconds) for the virtual Xen 60472ec16bc0SRyan Thibodeaux timers (default is 100000). This adjusts the minimum 60482ec16bc0SRyan Thibodeaux delta of virtualized Xen timers, where lower values 60492ec16bc0SRyan Thibodeaux improve timer resolution at the expense of processing 60502ec16bc0SRyan Thibodeaux more timer interrupts. 60512ec16bc0SRyan Thibodeaux 6052e99502f7SJuergen Gross xen.event_eoi_delay= [XEN] 6053e99502f7SJuergen Gross How long to delay EOI handling in case of event 6054e99502f7SJuergen Gross storms (jiffies). Default is 10. 6055e99502f7SJuergen Gross 6056e99502f7SJuergen Gross xen.event_loop_timeout= [XEN] 6057e99502f7SJuergen Gross After which time (jiffies) the event handling loop 6058e99502f7SJuergen Gross should start to delay EOI handling. Default is 2. 6059e99502f7SJuergen Gross 60601a89c1dcSJuergen Gross xen.fifo_events= [XEN] 60611a89c1dcSJuergen Gross Boolean parameter to disable using fifo event handling 60621a89c1dcSJuergen Gross even if available. Normally fifo event handling is 60631a89c1dcSJuergen Gross preferred over the 2-level event handling, as it is 60641a89c1dcSJuergen Gross fairer and the number of possible event channels is 60651a89c1dcSJuergen Gross much higher. Default is on (use fifo events). 60661a89c1dcSJuergen Gross 606730978346SZhenzhong Duan nopv= [X86,XEN,KVM,HYPER_V,VMWARE] 606830978346SZhenzhong Duan Disables the PV optimizations forcing the guest to run 606930978346SZhenzhong Duan as generic guest with no PV drivers. Currently support 607030978346SZhenzhong Duan XEN HVM, KVM, HYPER_V and VMWARE guest. 607130978346SZhenzhong Duan 60729a3c05e6SZhenzhong Duan nopvspin [X86,XEN,KVM] 607305eee619SZhenzhong Duan Disables the qspinlock slow path using PV optimizations 607405eee619SZhenzhong Duan which allow the hypervisor to 'idle' the guest on lock 607505eee619SZhenzhong Duan contention. 607605eee619SZhenzhong Duan 6077e52347bdSJani Nikula xirc2ps_cs= [NET,PCMCIA] 6078e52347bdSJani Nikula Format: 6079e52347bdSJani Nikula <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] 6080c0addc9aSLaurentiu Tudor 6081ba45cff6SMichael Neuling xive= [PPC] 6082ba45cff6SMichael Neuling By default on POWER9 and above, the kernel will 6083ba45cff6SMichael Neuling natively use the XIVE interrupt controller. This option 6084ba45cff6SMichael Neuling allows the fallback firmware mode to be used: 6085ba45cff6SMichael Neuling 6086ba45cff6SMichael Neuling off Fallback to firmware control of XIVE interrupt 6087ba45cff6SMichael Neuling controller on both pseries and powernv 6088ba45cff6SMichael Neuling platforms. Only useful on POWER9 and above. 6089ba45cff6SMichael Neuling 6090c0addc9aSLaurentiu Tudor xhci-hcd.quirks [USB,KNL] 6091c0addc9aSLaurentiu Tudor A hex value specifying bitmask with supplemental xhci 6092c0addc9aSLaurentiu Tudor host controller quirks. Meaning of each bit can be 6093c0addc9aSLaurentiu Tudor consulted in header drivers/usb/host/xhci.h. 60946278f55bSGustavo Romero 60956278f55bSGustavo Romero xmon [PPC] 60966278f55bSGustavo Romero Format: { early | on | rw | ro | off } 60976278f55bSGustavo Romero Controls if xmon debugger is enabled. Default is off. 60986278f55bSGustavo Romero Passing only "xmon" is equivalent to "xmon=early". 60996278f55bSGustavo Romero early Call xmon as early as possible on boot; xmon 61006278f55bSGustavo Romero debugger is called from setup_arch(). 61016278f55bSGustavo Romero on xmon debugger hooks will be installed so xmon 61026278f55bSGustavo Romero is only called on a kernel crash. Default mode, 61036278f55bSGustavo Romero i.e. either "ro" or "rw" mode, is controlled 61046278f55bSGustavo Romero with CONFIG_XMON_DEFAULT_RO_MODE. 61056278f55bSGustavo Romero rw xmon debugger hooks will be installed so xmon 61066278f55bSGustavo Romero is called only on a kernel crash, mode is write, 61076278f55bSGustavo Romero meaning SPR registers, memory and, other data 61086278f55bSGustavo Romero can be written using xmon commands. 61096278f55bSGustavo Romero ro same as "rw" option above but SPR registers, 61106278f55bSGustavo Romero memory, and other data can't be written using 61116278f55bSGustavo Romero xmon commands. 61126278f55bSGustavo Romero off xmon is disabled. 6113