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 16e52347bdSJani Nikula See also Documentation/power/runtime_pm.txt, pci=noacpi 17e52347bdSJani Nikula 18e52347bdSJani Nikula acpi_apic_instance= [ACPI, IOAPIC] 19e52347bdSJani Nikula Format: <int> 20e52347bdSJani Nikula 2: use 2nd APIC table, if available 21e52347bdSJani Nikula 1,0: use 1st APIC table 22e52347bdSJani Nikula default: 0 23e52347bdSJani Nikula 24e52347bdSJani Nikula acpi_backlight= [HW,ACPI] 25e52347bdSJani Nikula acpi_backlight=vendor 26e52347bdSJani Nikula acpi_backlight=video 27e52347bdSJani Nikula If set to vendor, prefer vendor specific driver 28e52347bdSJani Nikula (e.g. thinkpad_acpi, sony_acpi, etc.) instead 29e52347bdSJani Nikula of the ACPI video.ko driver. 30e52347bdSJani Nikula 31e52347bdSJani Nikula acpi_force_32bit_fadt_addr 32e52347bdSJani Nikula force FADT to use 32 bit addresses rather than the 33e52347bdSJani Nikula 64 bit X_* addresses. Some firmware have broken 64 34e52347bdSJani Nikula bit addresses for force ACPI ignore these and use 35e52347bdSJani Nikula the older legacy 32 bit addresses. 36e52347bdSJani Nikula 37e52347bdSJani Nikula acpica_no_return_repair [HW, ACPI] 38e52347bdSJani Nikula Disable AML predefined validation mechanism 39e52347bdSJani Nikula This mechanism can repair the evaluation result to make 40e52347bdSJani Nikula the return objects more ACPI specification compliant. 41e52347bdSJani Nikula This option is useful for developers to identify the 42e52347bdSJani Nikula root cause of an AML interpreter issue when the issue 43e52347bdSJani Nikula has something to do with the repair mechanism. 44e52347bdSJani Nikula 45e52347bdSJani Nikula acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] 46e52347bdSJani Nikula acpi.debug_level= [HW,ACPI,ACPI_DEBUG] 47e52347bdSJani Nikula Format: <int> 48e52347bdSJani Nikula CONFIG_ACPI_DEBUG must be enabled to produce any ACPI 49e52347bdSJani Nikula debug output. Bits in debug_layer correspond to a 50e52347bdSJani Nikula _COMPONENT in an ACPI source file, e.g., 51e52347bdSJani Nikula #define _COMPONENT ACPI_PCI_COMPONENT 52e52347bdSJani Nikula Bits in debug_level correspond to a level in 53e52347bdSJani Nikula ACPI_DEBUG_PRINT statements, e.g., 54e52347bdSJani Nikula ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... 55e52347bdSJani Nikula The debug_level mask defaults to "info". See 56e52347bdSJani Nikula Documentation/acpi/debug.txt for more information about 57e52347bdSJani Nikula debug layers and levels. 58e52347bdSJani Nikula 59e52347bdSJani Nikula Enable processor driver info messages: 60e52347bdSJani Nikula acpi.debug_layer=0x20000000 61e52347bdSJani Nikula Enable PCI/PCI interrupt routing info messages: 62e52347bdSJani Nikula acpi.debug_layer=0x400000 63e52347bdSJani Nikula Enable AML "Debug" output, i.e., stores to the Debug 64e52347bdSJani Nikula object while interpreting AML: 65e52347bdSJani Nikula acpi.debug_layer=0xffffffff acpi.debug_level=0x2 66e52347bdSJani Nikula Enable all messages related to ACPI hardware: 67e52347bdSJani Nikula acpi.debug_layer=0x2 acpi.debug_level=0xffffffff 68e52347bdSJani Nikula 69e52347bdSJani Nikula Some values produce so much output that the system is 70e52347bdSJani Nikula unusable. The "log_buf_len" parameter may be useful 71e52347bdSJani Nikula if you need to capture more output. 72e52347bdSJani Nikula 73e52347bdSJani Nikula acpi_enforce_resources= [ACPI] 74e52347bdSJani Nikula { strict | lax | no } 75e52347bdSJani Nikula Check for resource conflicts between native drivers 76e52347bdSJani Nikula and ACPI OperationRegions (SystemIO and SystemMemory 77e52347bdSJani Nikula only). IO ports and memory declared in ACPI might be 78e52347bdSJani Nikula used by the ACPI subsystem in arbitrary AML code and 79e52347bdSJani Nikula can interfere with legacy drivers. 80e52347bdSJani Nikula strict (default): access to resources claimed by ACPI 81e52347bdSJani Nikula is denied; legacy drivers trying to access reserved 82e52347bdSJani Nikula resources will fail to bind to device using them. 83e52347bdSJani Nikula lax: access to resources claimed by ACPI is allowed; 84e52347bdSJani Nikula legacy drivers trying to access reserved resources 85e52347bdSJani Nikula will bind successfully but a warning message is logged. 86e52347bdSJani Nikula no: ACPI OperationRegions are not marked as reserved, 87e52347bdSJani Nikula no further checks are performed. 88e52347bdSJani Nikula 89e52347bdSJani Nikula acpi_force_table_verification [HW,ACPI] 90e52347bdSJani Nikula Enable table checksum verification during early stage. 91e52347bdSJani Nikula By default, this is disabled due to x86 early mapping 92e52347bdSJani Nikula size limitation. 93e52347bdSJani Nikula 94e52347bdSJani Nikula acpi_irq_balance [HW,ACPI] 95e52347bdSJani Nikula ACPI will balance active IRQs 96e52347bdSJani Nikula default in APIC mode 97e52347bdSJani Nikula 98e52347bdSJani Nikula acpi_irq_nobalance [HW,ACPI] 99e52347bdSJani Nikula ACPI will not move active IRQs (default) 100e52347bdSJani Nikula default in PIC mode 101e52347bdSJani Nikula 102e52347bdSJani Nikula acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA 103e52347bdSJani Nikula Format: <irq>,<irq>... 104e52347bdSJani Nikula 105e52347bdSJani Nikula acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for 106e52347bdSJani Nikula use by PCI 107e52347bdSJani Nikula Format: <irq>,<irq>... 108e52347bdSJani Nikula 109e52347bdSJani Nikula acpi_no_auto_serialize [HW,ACPI] 110e52347bdSJani Nikula Disable auto-serialization of AML methods 111e52347bdSJani Nikula AML control methods that contain the opcodes to create 112e52347bdSJani Nikula named objects will be marked as "Serialized" by the 113e52347bdSJani Nikula auto-serialization feature. 114e52347bdSJani Nikula This feature is enabled by default. 115e52347bdSJani Nikula This option allows to turn off the feature. 116e52347bdSJani Nikula 117e52347bdSJani Nikula acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump 118e52347bdSJani Nikula kernels. 119e52347bdSJani Nikula 120e52347bdSJani Nikula acpi_no_static_ssdt [HW,ACPI] 121e52347bdSJani Nikula Disable installation of static SSDTs at early boot time 122e52347bdSJani Nikula By default, SSDTs contained in the RSDT/XSDT will be 123e52347bdSJani Nikula installed automatically and they will appear under 124e52347bdSJani Nikula /sys/firmware/acpi/tables. 125e52347bdSJani Nikula This option turns off this feature. 126e52347bdSJani Nikula Note that specifying this option does not affect 127e52347bdSJani Nikula dynamic table installation which will install SSDT 128e52347bdSJani Nikula tables to /sys/firmware/acpi/tables/dynamic. 129e52347bdSJani Nikula 130e52347bdSJani Nikula acpi_rsdp= [ACPI,EFI,KEXEC] 131e52347bdSJani Nikula Pass the RSDP address to the kernel, mostly used 132e52347bdSJani Nikula on machines running EFI runtime service to boot the 133e52347bdSJani Nikula second kernel for kdump. 134e52347bdSJani Nikula 135e52347bdSJani Nikula acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS 136e52347bdSJani Nikula Format: To spoof as Windows 98: ="Microsoft Windows" 137e52347bdSJani Nikula 138e52347bdSJani Nikula acpi_rev_override [ACPI] Override the _REV object to return 5 (instead 139e52347bdSJani Nikula of 2 which is mandated by ACPI 6) as the supported ACPI 140e52347bdSJani Nikula specification revision (when using this switch, it may 141e52347bdSJani Nikula be necessary to carry out a cold reboot _twice_ in a 142e52347bdSJani Nikula row to make it take effect on the platform firmware). 143e52347bdSJani Nikula 144e52347bdSJani Nikula acpi_osi= [HW,ACPI] Modify list of supported OS interface strings 145e52347bdSJani Nikula acpi_osi="string1" # add string1 146e52347bdSJani Nikula acpi_osi="!string2" # remove string2 147e52347bdSJani Nikula acpi_osi=!* # remove all strings 148e52347bdSJani Nikula acpi_osi=! # disable all built-in OS vendor 149e52347bdSJani Nikula strings 150e52347bdSJani Nikula acpi_osi=!! # enable all built-in OS vendor 151e52347bdSJani Nikula strings 152e52347bdSJani Nikula acpi_osi= # disable all strings 153e52347bdSJani Nikula 154e52347bdSJani Nikula 'acpi_osi=!' can be used in combination with single or 155e52347bdSJani Nikula multiple 'acpi_osi="string1"' to support specific OS 156e52347bdSJani Nikula vendor string(s). Note that such command can only 157e52347bdSJani Nikula affect the default state of the OS vendor strings, thus 158e52347bdSJani Nikula it cannot affect the default state of the feature group 159e52347bdSJani Nikula strings and the current state of the OS vendor strings, 160e52347bdSJani Nikula specifying it multiple times through kernel command line 161e52347bdSJani Nikula is meaningless. This command is useful when one do not 162e52347bdSJani Nikula care about the state of the feature group strings which 163e52347bdSJani Nikula should be controlled by the OSPM. 164e52347bdSJani Nikula Examples: 165e52347bdSJani Nikula 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent 166e52347bdSJani Nikula to 'acpi_osi="Windows 2000" acpi_osi=!', they all 167e52347bdSJani Nikula can make '_OSI("Windows 2000")' TRUE. 168e52347bdSJani Nikula 169e52347bdSJani Nikula 'acpi_osi=' cannot be used in combination with other 170e52347bdSJani Nikula 'acpi_osi=' command lines, the _OSI method will not 171e52347bdSJani Nikula exist in the ACPI namespace. NOTE that such command can 172e52347bdSJani Nikula only affect the _OSI support state, thus specifying it 173e52347bdSJani Nikula multiple times through kernel command line is also 174e52347bdSJani Nikula meaningless. 175e52347bdSJani Nikula Examples: 176e52347bdSJani Nikula 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' 177e52347bdSJani Nikula FALSE. 178e52347bdSJani Nikula 179e52347bdSJani Nikula 'acpi_osi=!*' can be used in combination with single or 180e52347bdSJani Nikula multiple 'acpi_osi="string1"' to support specific 181e52347bdSJani Nikula string(s). Note that such command can affect the 182e52347bdSJani Nikula current state of both the OS vendor strings and the 183e52347bdSJani Nikula feature group strings, thus specifying it multiple times 184e52347bdSJani Nikula through kernel command line is meaningful. But it may 185e52347bdSJani Nikula still not able to affect the final state of a string if 186e52347bdSJani Nikula there are quirks related to this string. This command 187e52347bdSJani Nikula is useful when one want to control the state of the 188e52347bdSJani Nikula feature group strings to debug BIOS issues related to 189e52347bdSJani Nikula the OSPM features. 190e52347bdSJani Nikula Examples: 191e52347bdSJani Nikula 1. 'acpi_osi="Module Device" acpi_osi=!*' can make 192e52347bdSJani Nikula '_OSI("Module Device")' FALSE. 193e52347bdSJani Nikula 2. 'acpi_osi=!* acpi_osi="Module Device"' can make 194e52347bdSJani Nikula '_OSI("Module Device")' TRUE. 195e52347bdSJani Nikula 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is 196e52347bdSJani Nikula equivalent to 197e52347bdSJani Nikula 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' 198e52347bdSJani Nikula and 199e52347bdSJani Nikula 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', 200e52347bdSJani Nikula they all will make '_OSI("Windows 2000")' TRUE. 201e52347bdSJani Nikula 202e52347bdSJani Nikula acpi_pm_good [X86] 203e52347bdSJani Nikula Override the pmtimer bug detection: force the kernel 204e52347bdSJani Nikula to assume that this machine's pmtimer latches its value 205e52347bdSJani Nikula and always returns good values. 206e52347bdSJani Nikula 207e52347bdSJani Nikula acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode 208e52347bdSJani Nikula Format: { level | edge | high | low } 209e52347bdSJani Nikula 210e52347bdSJani Nikula acpi_skip_timer_override [HW,ACPI] 211e52347bdSJani Nikula Recognize and ignore IRQ0/pin2 Interrupt Override. 212e52347bdSJani Nikula For broken nForce2 BIOS resulting in XT-PIC timer. 213e52347bdSJani Nikula 214e52347bdSJani Nikula acpi_sleep= [HW,ACPI] Sleep options 215e52347bdSJani Nikula Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, 216e52347bdSJani Nikula old_ordering, nonvs, sci_force_enable } 217e52347bdSJani Nikula See Documentation/power/video.txt for information on 218e52347bdSJani Nikula s3_bios and s3_mode. 219e52347bdSJani Nikula s3_beep is for debugging; it makes the PC's speaker beep 220e52347bdSJani Nikula as soon as the kernel's real-mode entry point is called. 221e52347bdSJani Nikula s4_nohwsig prevents ACPI hardware signature from being 222e52347bdSJani Nikula used during resume from hibernation. 223e52347bdSJani Nikula old_ordering causes the ACPI 1.0 ordering of the _PTS 224e52347bdSJani Nikula control method, with respect to putting devices into 225e52347bdSJani Nikula low power states, to be enforced (the ACPI 2.0 ordering 226e52347bdSJani Nikula of _PTS is used by default). 227e52347bdSJani Nikula nonvs prevents the kernel from saving/restoring the 228e52347bdSJani Nikula ACPI NVS memory during suspend/hibernation and resume. 229e52347bdSJani Nikula sci_force_enable causes the kernel to set SCI_EN directly 230e52347bdSJani Nikula on resume from S1/S3 (which is against the ACPI spec, 231e52347bdSJani Nikula but some broken systems don't work without it). 232e52347bdSJani Nikula 233e52347bdSJani Nikula acpi_use_timer_override [HW,ACPI] 234e52347bdSJani Nikula Use timer override. For some broken Nvidia NF5 boards 235e52347bdSJani Nikula that require a timer override, but don't have HPET 236e52347bdSJani Nikula 237e52347bdSJani Nikula add_efi_memmap [EFI; X86] Include EFI memory map in 238e52347bdSJani Nikula kernel's map of available physical RAM. 239e52347bdSJani Nikula 240e52347bdSJani Nikula agp= [AGP] 241e52347bdSJani Nikula { off | try_unsupported } 242e52347bdSJani Nikula off: disable AGP support 243e52347bdSJani Nikula try_unsupported: try to drive unsupported chipsets 244e52347bdSJani Nikula (may crash computer or cause data corruption) 245e52347bdSJani Nikula 246e52347bdSJani Nikula ALSA [HW,ALSA] 247e52347bdSJani Nikula See Documentation/sound/alsa/alsa-parameters.txt 248e52347bdSJani Nikula 249e52347bdSJani Nikula alignment= [KNL,ARM] 250e52347bdSJani Nikula Allow the default userspace alignment fault handler 251e52347bdSJani Nikula behaviour to be specified. Bit 0 enables warnings, 252e52347bdSJani Nikula bit 1 enables fixups, and bit 2 sends a segfault. 253e52347bdSJani Nikula 254e52347bdSJani Nikula align_va_addr= [X86-64] 255e52347bdSJani Nikula Align virtual addresses by clearing slice [14:12] when 256e52347bdSJani Nikula allocating a VMA at process creation time. This option 257e52347bdSJani Nikula gives you up to 3% performance improvement on AMD F15h 258e52347bdSJani Nikula machines (where it is enabled by default) for a 259e52347bdSJani Nikula CPU-intensive style benchmark, and it can vary highly in 260e52347bdSJani Nikula a microbenchmark depending on workload and compiler. 261e52347bdSJani Nikula 262e52347bdSJani Nikula 32: only for 32-bit processes 263e52347bdSJani Nikula 64: only for 64-bit processes 264e52347bdSJani Nikula on: enable for both 32- and 64-bit processes 265e52347bdSJani Nikula off: disable for both 32- and 64-bit processes 266e52347bdSJani Nikula 267e52347bdSJani Nikula alloc_snapshot [FTRACE] 268e52347bdSJani Nikula Allocate the ftrace snapshot buffer on boot up when the 269e52347bdSJani Nikula main buffer is allocated. This is handy if debugging 270e52347bdSJani Nikula and you need to use tracing_snapshot() on boot up, and 271e52347bdSJani Nikula do not want to use tracing_snapshot_alloc() as it needs 272e52347bdSJani Nikula to be done where GFP_KERNEL allocations are allowed. 273e52347bdSJani Nikula 274e52347bdSJani Nikula amd_iommu= [HW,X86-64] 275e52347bdSJani Nikula Pass parameters to the AMD IOMMU driver in the system. 276e52347bdSJani Nikula Possible values are: 277e52347bdSJani Nikula fullflush - enable flushing of IO/TLB entries when 278e52347bdSJani Nikula they are unmapped. Otherwise they are 279e52347bdSJani Nikula flushed before they will be reused, which 280e52347bdSJani Nikula is a lot of faster 281e52347bdSJani Nikula off - do not initialize any AMD IOMMU found in 282e52347bdSJani Nikula the system 283e52347bdSJani Nikula force_isolation - Force device isolation for all 284e52347bdSJani Nikula devices. The IOMMU driver is not 285e52347bdSJani Nikula allowed anymore to lift isolation 286e52347bdSJani Nikula requirements as needed. This option 287e52347bdSJani Nikula does not override iommu=pt 288e52347bdSJani Nikula 289e52347bdSJani Nikula amd_iommu_dump= [HW,X86-64] 290e52347bdSJani Nikula Enable AMD IOMMU driver option to dump the ACPI table 291e52347bdSJani Nikula for AMD IOMMU. With this option enabled, AMD IOMMU 292e52347bdSJani Nikula driver will print ACPI tables for AMD IOMMU during 293e52347bdSJani Nikula IOMMU initialization. 294e52347bdSJani Nikula 295e52347bdSJani Nikula amd_iommu_intr= [HW,X86-64] 296e52347bdSJani Nikula Specifies one of the following AMD IOMMU interrupt 297e52347bdSJani Nikula remapping modes: 298e52347bdSJani Nikula legacy - Use legacy interrupt remapping mode. 299e52347bdSJani Nikula vapic - Use virtual APIC mode, which allows IOMMU 300e52347bdSJani Nikula to inject interrupts directly into guest. 301e52347bdSJani Nikula This mode requires kvm-amd.avic=1. 302e52347bdSJani Nikula (Default when IOMMU HW support is present.) 303e52347bdSJani Nikula 304e52347bdSJani Nikula amijoy.map= [HW,JOY] Amiga joystick support 305e52347bdSJani Nikula Map of devices attached to JOY0DAT and JOY1DAT 306e52347bdSJani Nikula Format: <a>,<b> 307e52347bdSJani Nikula See also Documentation/input/joystick.txt 308e52347bdSJani Nikula 309e52347bdSJani Nikula analog.map= [HW,JOY] Analog joystick and gamepad support 310e52347bdSJani Nikula Specifies type or capabilities of an analog joystick 311e52347bdSJani Nikula connected to one of 16 gameports 312e52347bdSJani Nikula Format: <type1>,<type2>,..<type16> 313e52347bdSJani Nikula 314e52347bdSJani Nikula apc= [HW,SPARC] 315e52347bdSJani Nikula Power management functions (SPARCstation-4/5 + deriv.) 316e52347bdSJani Nikula Format: noidle 317e52347bdSJani Nikula Disable APC CPU standby support. SPARCstation-Fox does 318e52347bdSJani Nikula not play well with APC CPU idle - disable it if you have 319e52347bdSJani Nikula APC and your system crashes randomly. 320e52347bdSJani Nikula 321e52347bdSJani Nikula apic= [APIC,X86-32] Advanced Programmable Interrupt Controller 322e52347bdSJani Nikula Change the output verbosity whilst booting 323e52347bdSJani Nikula Format: { quiet (default) | verbose | debug } 324e52347bdSJani Nikula Change the amount of debugging information output 325e52347bdSJani Nikula when initialising the APIC and IO-APIC components. 326e52347bdSJani Nikula 327e52347bdSJani Nikula apic_extnmi= [APIC,X86] External NMI delivery setting 328e52347bdSJani Nikula Format: { bsp (default) | all | none } 329e52347bdSJani Nikula bsp: External NMI is delivered only to CPU 0 330e52347bdSJani Nikula all: External NMIs are broadcast to all CPUs as a 331e52347bdSJani Nikula backup of CPU 0 332e52347bdSJani Nikula none: External NMI is masked for all CPUs. This is 333e52347bdSJani Nikula useful so that a dump capture kernel won't be 334e52347bdSJani Nikula shot down by NMI 335e52347bdSJani Nikula 336e52347bdSJani Nikula autoconf= [IPV6] 337e52347bdSJani Nikula See Documentation/networking/ipv6.txt. 338e52347bdSJani Nikula 339e52347bdSJani Nikula show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller 340e52347bdSJani Nikula Limit apic dumping. The parameter defines the maximal 341e52347bdSJani Nikula number of local apics being dumped. Also it is possible 342e52347bdSJani Nikula to set it to "all" by meaning -- no limit here. 343e52347bdSJani Nikula Format: { 1 (default) | 2 | ... | all }. 344e52347bdSJani Nikula The parameter valid if only apic=debug or 345e52347bdSJani Nikula apic=verbose is specified. 346e52347bdSJani Nikula Example: apic=debug show_lapic=all 347e52347bdSJani Nikula 348e52347bdSJani Nikula apm= [APM] Advanced Power Management 349e52347bdSJani Nikula See header of arch/x86/kernel/apm_32.c. 350e52347bdSJani Nikula 351e52347bdSJani Nikula arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards 352e52347bdSJani Nikula Format: <io>,<irq>,<nodeID> 353e52347bdSJani Nikula 354e52347bdSJani Nikula ataflop= [HW,M68k] 355e52347bdSJani Nikula 356e52347bdSJani Nikula atarimouse= [HW,MOUSE] Atari Mouse 357e52347bdSJani Nikula 358e52347bdSJani Nikula atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, 359e52347bdSJani Nikula EzKey and similar keyboards 360e52347bdSJani Nikula 361e52347bdSJani Nikula atkbd.reset= [HW] Reset keyboard during initialization 362e52347bdSJani Nikula 363e52347bdSJani Nikula atkbd.set= [HW] Select keyboard code set 364e52347bdSJani Nikula Format: <int> (2 = AT (default), 3 = PS/2) 365e52347bdSJani Nikula 366e52347bdSJani Nikula atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar 367e52347bdSJani Nikula keyboards 368e52347bdSJani Nikula 369e52347bdSJani Nikula atkbd.softraw= [HW] Choose between synthetic and real raw mode 370e52347bdSJani Nikula Format: <bool> (0 = real, 1 = synthetic (default)) 371e52347bdSJani Nikula 372e52347bdSJani Nikula atkbd.softrepeat= [HW] 373e52347bdSJani Nikula Use software keyboard repeat 374e52347bdSJani Nikula 375e52347bdSJani Nikula audit= [KNL] Enable the audit sub-system 376e52347bdSJani Nikula Format: { "0" | "1" } (0 = disabled, 1 = enabled) 377e52347bdSJani Nikula 0 - kernel audit is disabled and can not be enabled 378e52347bdSJani Nikula until the next reboot 379e52347bdSJani Nikula unset - kernel audit is initialized but disabled and 380e52347bdSJani Nikula will be fully enabled by the userspace auditd. 381e52347bdSJani Nikula 1 - kernel audit is initialized and partially enabled, 382e52347bdSJani Nikula storing at most audit_backlog_limit messages in 383e52347bdSJani Nikula RAM until it is fully enabled by the userspace 384e52347bdSJani Nikula auditd. 385e52347bdSJani Nikula Default: unset 386e52347bdSJani Nikula 387e52347bdSJani Nikula audit_backlog_limit= [KNL] Set the audit queue size limit. 388e52347bdSJani Nikula Format: <int> (must be >=0) 389e52347bdSJani Nikula Default: 64 390e52347bdSJani Nikula 391e52347bdSJani Nikula bau= [X86_UV] Enable the BAU on SGI UV. The default 392e52347bdSJani Nikula behavior is to disable the BAU (i.e. bau=0). 393e52347bdSJani Nikula Format: { "0" | "1" } 394e52347bdSJani Nikula 0 - Disable the BAU. 395e52347bdSJani Nikula 1 - Enable the BAU. 396e52347bdSJani Nikula unset - Disable the BAU. 397e52347bdSJani Nikula 398e52347bdSJani Nikula baycom_epp= [HW,AX25] 399e52347bdSJani Nikula Format: <io>,<mode> 400e52347bdSJani Nikula 401e52347bdSJani Nikula baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem 402e52347bdSJani Nikula Format: <io>,<mode> 403e52347bdSJani Nikula See header of drivers/net/hamradio/baycom_par.c. 404e52347bdSJani Nikula 405e52347bdSJani Nikula baycom_ser_fdx= [HW,AX25] 406e52347bdSJani Nikula BayCom Serial Port AX.25 Modem (Full Duplex Mode) 407e52347bdSJani Nikula Format: <io>,<irq>,<mode>[,<baud>] 408e52347bdSJani Nikula See header of drivers/net/hamradio/baycom_ser_fdx.c. 409e52347bdSJani Nikula 410e52347bdSJani Nikula baycom_ser_hdx= [HW,AX25] 411e52347bdSJani Nikula BayCom Serial Port AX.25 Modem (Half Duplex Mode) 412e52347bdSJani Nikula Format: <io>,<irq>,<mode> 413e52347bdSJani Nikula See header of drivers/net/hamradio/baycom_ser_hdx.c. 414e52347bdSJani Nikula 415e52347bdSJani Nikula blkdevparts= Manual partition parsing of block device(s) for 416e52347bdSJani Nikula embedded devices based on command line input. 417e52347bdSJani Nikula See Documentation/block/cmdline-partition.txt 418e52347bdSJani Nikula 419e52347bdSJani Nikula boot_delay= Milliseconds to delay each printk during boot. 420e52347bdSJani Nikula Values larger than 10 seconds (10000) are changed to 421e52347bdSJani Nikula no delay (0). 422e52347bdSJani Nikula Format: integer 423e52347bdSJani Nikula 424e52347bdSJani Nikula bootmem_debug [KNL] Enable bootmem allocator debug messages. 425e52347bdSJani Nikula 426e52347bdSJani Nikula bert_disable [ACPI] 427e52347bdSJani Nikula Disable BERT OS support on buggy BIOSes. 428e52347bdSJani Nikula 429e52347bdSJani Nikula bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) 430e52347bdSJani Nikula bttv.radio= Most important insmod options are available as 431e52347bdSJani Nikula kernel args too. 432e52347bdSJani Nikula bttv.pll= See Documentation/video4linux/bttv/Insmod-options 433e52347bdSJani Nikula bttv.tuner= 434e52347bdSJani Nikula 435e52347bdSJani Nikula bulk_remove=off [PPC] This parameter disables the use of the pSeries 436e52347bdSJani Nikula firmware feature for flushing multiple hpte entries 437e52347bdSJani Nikula at a time. 438e52347bdSJani Nikula 439e52347bdSJani Nikula c101= [NET] Moxa C101 synchronous serial card 440e52347bdSJani Nikula 441e52347bdSJani Nikula cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. 442e52347bdSJani Nikula Sometimes CPU hardware bugs make them report the cache 443e52347bdSJani Nikula size incorrectly. The kernel will attempt work arounds 444e52347bdSJani Nikula to fix known problems, but for some CPUs it is not 445e52347bdSJani Nikula possible to determine what the correct size should be. 446e52347bdSJani Nikula This option provides an override for these situations. 447e52347bdSJani Nikula 448e52347bdSJani Nikula ca_keys= [KEYS] This parameter identifies a specific key(s) on 449e52347bdSJani Nikula the system trusted keyring to be used for certificate 450e52347bdSJani Nikula trust validation. 451e52347bdSJani Nikula format: { id:<keyid> | builtin } 452e52347bdSJani Nikula 453e52347bdSJani Nikula cca= [MIPS] Override the kernel pages' cache coherency 454e52347bdSJani Nikula algorithm. Accepted values range from 0 to 7 455e52347bdSJani Nikula inclusive. See arch/mips/include/asm/pgtable-bits.h 456e52347bdSJani Nikula for platform specific values (SB1, Loongson3 and 457e52347bdSJani Nikula others). 458e52347bdSJani Nikula 459e52347bdSJani Nikula ccw_timeout_log [S390] 460e52347bdSJani Nikula See Documentation/s390/CommonIO for details. 461e52347bdSJani Nikula 462e52347bdSJani Nikula cgroup_disable= [KNL] Disable a particular controller 463e52347bdSJani Nikula Format: {name of the controller(s) to disable} 464e52347bdSJani Nikula The effects of cgroup_disable=foo are: 465e52347bdSJani Nikula - foo isn't auto-mounted if you mount all cgroups in 466e52347bdSJani Nikula a single hierarchy 467e52347bdSJani Nikula - foo isn't visible as an individually mountable 468e52347bdSJani Nikula subsystem 469e52347bdSJani Nikula {Currently only "memory" controller deal with this and 470e52347bdSJani Nikula cut the overhead, others just disable the usage. So 471e52347bdSJani Nikula only cgroup_disable=memory is actually worthy} 472e52347bdSJani Nikula 473e52347bdSJani Nikula cgroup_no_v1= [KNL] Disable one, multiple, all cgroup controllers in v1 474e52347bdSJani Nikula Format: { controller[,controller...] | "all" } 475e52347bdSJani Nikula Like cgroup_disable, but only applies to cgroup v1; 476e52347bdSJani Nikula the blacklisted controllers remain available in cgroup2. 477e52347bdSJani Nikula 478e52347bdSJani Nikula cgroup.memory= [KNL] Pass options to the cgroup memory controller. 479e52347bdSJani Nikula Format: <string> 480e52347bdSJani Nikula nosocket -- Disable socket memory accounting. 481e52347bdSJani Nikula nokmem -- Disable kernel memory accounting. 482e52347bdSJani Nikula 483e52347bdSJani Nikula checkreqprot [SELINUX] Set initial checkreqprot flag value. 484e52347bdSJani Nikula Format: { "0" | "1" } 485e52347bdSJani Nikula See security/selinux/Kconfig help text. 486e52347bdSJani Nikula 0 -- check protection applied by kernel (includes 487e52347bdSJani Nikula any implied execute protection). 488e52347bdSJani Nikula 1 -- check protection requested by application. 489e52347bdSJani Nikula Default value is set via a kernel config option. 490e52347bdSJani Nikula Value can be changed at runtime via 491e52347bdSJani Nikula /selinux/checkreqprot. 492e52347bdSJani Nikula 493e52347bdSJani Nikula cio_ignore= [S390] 494e52347bdSJani Nikula See Documentation/s390/CommonIO for details. 495e52347bdSJani Nikula clk_ignore_unused 496e52347bdSJani Nikula [CLK] 497e52347bdSJani Nikula Prevents the clock framework from automatically gating 498e52347bdSJani Nikula clocks that have not been explicitly enabled by a Linux 499e52347bdSJani Nikula device driver but are enabled in hardware at reset or 500e52347bdSJani Nikula by the bootloader/firmware. Note that this does not 501e52347bdSJani Nikula force such clocks to be always-on nor does it reserve 502e52347bdSJani Nikula those clocks in any way. This parameter is useful for 503e52347bdSJani Nikula debug and development, but should not be needed on a 504e52347bdSJani Nikula platform with proper driver support. For more 505e52347bdSJani Nikula information, see Documentation/clk.txt. 506e52347bdSJani Nikula 507e52347bdSJani Nikula clock= [BUGS=X86-32, HW] gettimeofday clocksource override. 508e52347bdSJani Nikula [Deprecated] 509e52347bdSJani Nikula Forces specified clocksource (if available) to be used 510e52347bdSJani Nikula when calculating gettimeofday(). If specified 511e52347bdSJani Nikula clocksource is not available, it defaults to PIT. 512e52347bdSJani Nikula Format: { pit | tsc | cyclone | pmtmr } 513e52347bdSJani Nikula 514e52347bdSJani Nikula clocksource= Override the default clocksource 515e52347bdSJani Nikula Format: <string> 516e52347bdSJani Nikula Override the default clocksource and use the clocksource 517e52347bdSJani Nikula with the name specified. 518e52347bdSJani Nikula Some clocksource names to choose from, depending on 519e52347bdSJani Nikula the platform: 520e52347bdSJani Nikula [all] jiffies (this is the base, fallback clocksource) 521e52347bdSJani Nikula [ACPI] acpi_pm 522e52347bdSJani Nikula [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, 523e52347bdSJani Nikula pxa_timer,timer3,32k_counter,timer0_1 524e52347bdSJani Nikula [AVR32] avr32 525e52347bdSJani Nikula [X86-32] pit,hpet,tsc; 526e52347bdSJani Nikula scx200_hrt on Geode; cyclone on IBM x440 527e52347bdSJani Nikula [MIPS] MIPS 528e52347bdSJani Nikula [PARISC] cr16 529e52347bdSJani Nikula [S390] tod 530e52347bdSJani Nikula [SH] SuperH 531e52347bdSJani Nikula [SPARC64] tick 532e52347bdSJani Nikula [X86-64] hpet,tsc 533e52347bdSJani Nikula 534e52347bdSJani Nikula clocksource.arm_arch_timer.evtstrm= 535e52347bdSJani Nikula [ARM,ARM64] 536e52347bdSJani Nikula Format: <bool> 537e52347bdSJani Nikula Enable/disable the eventstream feature of the ARM 538e52347bdSJani Nikula architected timer so that code using WFE-based polling 539e52347bdSJani Nikula loops can be debugged more effectively on production 540e52347bdSJani Nikula systems. 541e52347bdSJani Nikula 542e52347bdSJani Nikula clocksource.arm_arch_timer.fsl-a008585= 543e52347bdSJani Nikula [ARM64] 544e52347bdSJani Nikula Format: <bool> 545e52347bdSJani Nikula Enable/disable the workaround of Freescale/NXP 546e52347bdSJani Nikula erratum A-008585. This can be useful for KVM 547e52347bdSJani Nikula guests, if the guest device tree doesn't show the 548e52347bdSJani Nikula erratum. If unspecified, the workaround is 549e52347bdSJani Nikula enabled based on the device tree. 550e52347bdSJani Nikula 551e52347bdSJani Nikula clearcpuid=BITNUM [X86] 552e52347bdSJani Nikula Disable CPUID feature X for the kernel. See 553e52347bdSJani Nikula arch/x86/include/asm/cpufeatures.h for the valid bit 554e52347bdSJani Nikula numbers. Note the Linux specific bits are not necessarily 555e52347bdSJani Nikula stable over kernel options, but the vendor specific 556e52347bdSJani Nikula ones should be. 557e52347bdSJani Nikula Also note that user programs calling CPUID directly 558e52347bdSJani Nikula or using the feature without checking anything 559e52347bdSJani Nikula will still see it. This just prevents it from 560e52347bdSJani Nikula being used by the kernel or shown in /proc/cpuinfo. 561e52347bdSJani Nikula Also note the kernel might malfunction if you disable 562e52347bdSJani Nikula some critical bits. 563e52347bdSJani Nikula 564e52347bdSJani Nikula cma=nn[MG]@[start[MG][-end[MG]]] 565e52347bdSJani Nikula [ARM,X86,KNL] 566e52347bdSJani Nikula Sets the size of kernel global memory area for 567e52347bdSJani Nikula contiguous memory allocations and optionally the 568e52347bdSJani Nikula placement constraint by the physical address range of 569e52347bdSJani Nikula memory allocations. A value of 0 disables CMA 570e52347bdSJani Nikula altogether. For more information, see 571e52347bdSJani Nikula include/linux/dma-contiguous.h 572e52347bdSJani Nikula 573e52347bdSJani Nikula cmo_free_hint= [PPC] Format: { yes | no } 574e52347bdSJani Nikula Specify whether pages are marked as being inactive 575e52347bdSJani Nikula when they are freed. This is used in CMO environments 576e52347bdSJani Nikula to determine OS memory pressure for page stealing by 577e52347bdSJani Nikula a hypervisor. 578e52347bdSJani Nikula Default: yes 579e52347bdSJani Nikula 580e52347bdSJani Nikula coherent_pool=nn[KMG] [ARM,KNL] 581e52347bdSJani Nikula Sets the size of memory pool for coherent, atomic dma 582e52347bdSJani Nikula allocations, by default set to 256K. 583e52347bdSJani Nikula 584e52347bdSJani Nikula code_bytes [X86] How many bytes of object code to print 585e52347bdSJani Nikula in an oops report. 586e52347bdSJani Nikula Range: 0 - 8192 587e52347bdSJani Nikula Default: 64 588e52347bdSJani Nikula 589e52347bdSJani Nikula com20020= [HW,NET] ARCnet - COM20020 chipset 590e52347bdSJani Nikula Format: 591e52347bdSJani Nikula <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 592e52347bdSJani Nikula 593e52347bdSJani Nikula com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) 594e52347bdSJani Nikula Format: <io>[,<irq>] 595e52347bdSJani Nikula 596e52347bdSJani Nikula com90xx= [HW,NET] 597e52347bdSJani Nikula ARCnet - COM90xx chipset (memory-mapped buffers) 598e52347bdSJani Nikula Format: <io>[,<irq>[,<memstart>]] 599e52347bdSJani Nikula 600e52347bdSJani Nikula condev= [HW,S390] console device 601e52347bdSJani Nikula conmode= 602e52347bdSJani Nikula 603e52347bdSJani Nikula console= [KNL] Output console device and options. 604e52347bdSJani Nikula 605e52347bdSJani Nikula tty<n> Use the virtual console device <n>. 606e52347bdSJani Nikula 607e52347bdSJani Nikula ttyS<n>[,options] 608e52347bdSJani Nikula ttyUSB0[,options] 609e52347bdSJani Nikula Use the specified serial port. The options are of 610e52347bdSJani Nikula the form "bbbbpnf", where "bbbb" is the baud rate, 611e52347bdSJani Nikula "p" is parity ("n", "o", or "e"), "n" is number of 612e52347bdSJani Nikula bits, and "f" is flow control ("r" for RTS or 613e52347bdSJani Nikula omit it). Default is "9600n8". 614e52347bdSJani Nikula 615e52347bdSJani Nikula See Documentation/admin-guide/serial-console.rst for more 616e52347bdSJani Nikula information. See 617e52347bdSJani Nikula Documentation/networking/netconsole.txt for an 618e52347bdSJani Nikula alternative. 619e52347bdSJani Nikula 620e52347bdSJani Nikula uart[8250],io,<addr>[,options] 621e52347bdSJani Nikula uart[8250],mmio,<addr>[,options] 622e52347bdSJani Nikula uart[8250],mmio16,<addr>[,options] 623e52347bdSJani Nikula uart[8250],mmio32,<addr>[,options] 624e52347bdSJani Nikula uart[8250],0x<addr>[,options] 625e52347bdSJani Nikula Start an early, polled-mode console on the 8250/16550 626e52347bdSJani Nikula UART at the specified I/O port or MMIO address, 627e52347bdSJani Nikula switching to the matching ttyS device later. 628e52347bdSJani Nikula MMIO inter-register address stride is either 8-bit 629e52347bdSJani Nikula (mmio), 16-bit (mmio16), or 32-bit (mmio32). 630e52347bdSJani Nikula If none of [io|mmio|mmio16|mmio32], <addr> is assumed 631e52347bdSJani Nikula to be equivalent to 'mmio'. 'options' are specified in 632e52347bdSJani Nikula the same format described for ttyS above; if unspecified, 633e52347bdSJani Nikula the h/w is not re-initialized. 634e52347bdSJani Nikula 635e52347bdSJani Nikula hvc<n> Use the hypervisor console device <n>. This is for 636e52347bdSJani Nikula both Xen and PowerPC hypervisors. 637e52347bdSJani Nikula 638e52347bdSJani Nikula If the device connected to the port is not a TTY but a braille 639e52347bdSJani Nikula device, prepend "brl," before the device type, for instance 640e52347bdSJani Nikula console=brl,ttyS0 641e52347bdSJani Nikula For now, only VisioBraille is supported. 642e52347bdSJani Nikula 643e52347bdSJani Nikula consoleblank= [KNL] The console blank (screen saver) timeout in 644e52347bdSJani Nikula seconds. Defaults to 10*60 = 10mins. A value of 0 645e52347bdSJani Nikula disables the blank timer. 646e52347bdSJani Nikula 647e52347bdSJani Nikula coredump_filter= 648e52347bdSJani Nikula [KNL] Change the default value for 649e52347bdSJani Nikula /proc/<pid>/coredump_filter. 650e52347bdSJani Nikula See also Documentation/filesystems/proc.txt. 651e52347bdSJani Nikula 652e52347bdSJani Nikula cpuidle.off=1 [CPU_IDLE] 653e52347bdSJani Nikula disable the cpuidle sub-system 654e52347bdSJani Nikula 655e52347bdSJani Nikula cpu_init_udelay=N 656e52347bdSJani Nikula [X86] Delay for N microsec between assert and de-assert 657e52347bdSJani Nikula of APIC INIT to start processors. This delay occurs 658e52347bdSJani Nikula on every CPU online, such as boot, and resume from suspend. 659e52347bdSJani Nikula Default: 10000 660e52347bdSJani Nikula 661e52347bdSJani Nikula cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 662e52347bdSJani Nikula Format: 663e52347bdSJani Nikula <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 664e52347bdSJani Nikula 665e52347bdSJani Nikula crashkernel=size[KMG][@offset[KMG]] 666e52347bdSJani Nikula [KNL] Using kexec, Linux can switch to a 'crash kernel' 667e52347bdSJani Nikula upon panic. This parameter reserves the physical 668e52347bdSJani Nikula memory region [offset, offset + size] for that kernel 669e52347bdSJani Nikula image. If '@offset' is omitted, then a suitable offset 670e52347bdSJani Nikula is selected automatically. Check 671e52347bdSJani Nikula Documentation/kdump/kdump.txt for further details. 672e52347bdSJani Nikula 673e52347bdSJani Nikula crashkernel=range1:size1[,range2:size2,...][@offset] 674e52347bdSJani Nikula [KNL] Same as above, but depends on the memory 675e52347bdSJani Nikula in the running system. The syntax of range is 676e52347bdSJani Nikula start-[end] where start and end are both 677e52347bdSJani Nikula a memory unit (amount[KMG]). See also 678e52347bdSJani Nikula Documentation/kdump/kdump.txt for an example. 679e52347bdSJani Nikula 680e52347bdSJani Nikula crashkernel=size[KMG],high 681e52347bdSJani Nikula [KNL, x86_64] range could be above 4G. Allow kernel 682e52347bdSJani Nikula to allocate physical memory region from top, so could 683e52347bdSJani Nikula be above 4G if system have more than 4G ram installed. 684e52347bdSJani Nikula Otherwise memory region will be allocated below 4G, if 685e52347bdSJani Nikula available. 686e52347bdSJani Nikula It will be ignored if crashkernel=X is specified. 687e52347bdSJani Nikula crashkernel=size[KMG],low 688e52347bdSJani Nikula [KNL, x86_64] range under 4G. When crashkernel=X,high 689e52347bdSJani Nikula is passed, kernel could allocate physical memory region 690e52347bdSJani Nikula above 4G, that cause second kernel crash on system 691e52347bdSJani Nikula that require some amount of low memory, e.g. swiotlb 692e52347bdSJani Nikula requires at least 64M+32K low memory, also enough extra 693e52347bdSJani Nikula low memory is needed to make sure DMA buffers for 32-bit 694e52347bdSJani Nikula devices won't run out. Kernel would try to allocate at 695e52347bdSJani Nikula at least 256M below 4G automatically. 696e52347bdSJani Nikula This one let user to specify own low range under 4G 697e52347bdSJani Nikula for second kernel instead. 698e52347bdSJani Nikula 0: to disable low allocation. 699e52347bdSJani Nikula It will be ignored when crashkernel=X,high is not used 700e52347bdSJani Nikula or memory reserved is below 4G. 701e52347bdSJani Nikula 702e52347bdSJani Nikula cryptomgr.notests 703e52347bdSJani Nikula [KNL] Disable crypto self-tests 704e52347bdSJani Nikula 705e52347bdSJani Nikula cs89x0_dma= [HW,NET] 706e52347bdSJani Nikula Format: <dma> 707e52347bdSJani Nikula 708e52347bdSJani Nikula cs89x0_media= [HW,NET] 709e52347bdSJani Nikula Format: { rj45 | aui | bnc } 710e52347bdSJani Nikula 711e52347bdSJani Nikula dasd= [HW,NET] 712e52347bdSJani Nikula See header of drivers/s390/block/dasd_devmap.c. 713e52347bdSJani Nikula 714e52347bdSJani Nikula db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port 715e52347bdSJani Nikula (one device per port) 716e52347bdSJani Nikula Format: <port#>,<type> 717e52347bdSJani Nikula See also Documentation/input/joystick-parport.txt 718e52347bdSJani Nikula 719e52347bdSJani Nikula ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot 720e52347bdSJani Nikula time. See Documentation/dynamic-debug-howto.txt for 721e52347bdSJani Nikula details. Deprecated, see dyndbg. 722e52347bdSJani Nikula 723e52347bdSJani Nikula debug [KNL] Enable kernel debugging (events log level). 724e52347bdSJani Nikula 725e52347bdSJani Nikula debug_locks_verbose= 726e52347bdSJani Nikula [KNL] verbose self-tests 727e52347bdSJani Nikula Format=<0|1> 728e52347bdSJani Nikula Print debugging info while doing the locking API 729e52347bdSJani Nikula self-tests. 730e52347bdSJani Nikula We default to 0 (no extra messages), setting it to 731e52347bdSJani Nikula 1 will print _a lot_ more information - normally 732e52347bdSJani Nikula only useful to kernel developers. 733e52347bdSJani Nikula 734e52347bdSJani Nikula debug_objects [KNL] Enable object debugging 735e52347bdSJani Nikula 736e52347bdSJani Nikula no_debug_objects 737e52347bdSJani Nikula [KNL] Disable object debugging 738e52347bdSJani Nikula 739e52347bdSJani Nikula debug_guardpage_minorder= 740e52347bdSJani Nikula [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this 741e52347bdSJani Nikula parameter allows control of the order of pages that will 742e52347bdSJani Nikula be intentionally kept free (and hence protected) by the 743e52347bdSJani Nikula buddy allocator. Bigger value increase the probability 744e52347bdSJani Nikula of catching random memory corruption, but reduce the 745e52347bdSJani Nikula amount of memory for normal system use. The maximum 746e52347bdSJani Nikula possible value is MAX_ORDER/2. Setting this parameter 747e52347bdSJani Nikula to 1 or 2 should be enough to identify most random 748e52347bdSJani Nikula memory corruption problems caused by bugs in kernel or 749e52347bdSJani Nikula driver code when a CPU writes to (or reads from) a 750e52347bdSJani Nikula random memory location. Note that there exists a class 751e52347bdSJani Nikula of memory corruptions problems caused by buggy H/W or 752e52347bdSJani Nikula F/W or by drivers badly programing DMA (basically when 753e52347bdSJani Nikula memory is written at bus level and the CPU MMU is 754e52347bdSJani Nikula bypassed) which are not detectable by 755e52347bdSJani Nikula CONFIG_DEBUG_PAGEALLOC, hence this option will not help 756e52347bdSJani Nikula tracking down these problems. 757e52347bdSJani Nikula 758e52347bdSJani Nikula debug_pagealloc= 759e52347bdSJani Nikula [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this 760e52347bdSJani Nikula parameter enables the feature at boot time. In 761e52347bdSJani Nikula default, it is disabled. We can avoid allocating huge 762e52347bdSJani Nikula chunk of memory for debug pagealloc if we don't enable 763e52347bdSJani Nikula it at boot time and the system will work mostly same 764e52347bdSJani Nikula with the kernel built without CONFIG_DEBUG_PAGEALLOC. 765e52347bdSJani Nikula on: enable the feature 766e52347bdSJani Nikula 767e52347bdSJani Nikula debugpat [X86] Enable PAT debugging 768e52347bdSJani Nikula 769e52347bdSJani Nikula decnet.addr= [HW,NET] 770e52347bdSJani Nikula Format: <area>[,<node>] 771e52347bdSJani Nikula See also Documentation/networking/decnet.txt. 772e52347bdSJani Nikula 773e52347bdSJani Nikula default_hugepagesz= 774e52347bdSJani Nikula [same as hugepagesz=] The size of the default 775e52347bdSJani Nikula HugeTLB page size. This is the size represented by 776e52347bdSJani Nikula the legacy /proc/ hugepages APIs, used for SHM, and 777e52347bdSJani Nikula default size when mounting hugetlbfs filesystems. 778e52347bdSJani Nikula Defaults to the default architecture's huge page size 779e52347bdSJani Nikula if not specified. 780e52347bdSJani Nikula 781e52347bdSJani Nikula dhash_entries= [KNL] 782e52347bdSJani Nikula Set number of hash buckets for dentry cache. 783e52347bdSJani Nikula 784e52347bdSJani Nikula disable_1tb_segments [PPC] 785e52347bdSJani Nikula Disables the use of 1TB hash page table segments. This 786e52347bdSJani Nikula causes the kernel to fall back to 256MB segments which 787e52347bdSJani Nikula can be useful when debugging issues that require an SLB 788e52347bdSJani Nikula miss to occur. 789e52347bdSJani Nikula 790e52347bdSJani Nikula disable= [IPV6] 791e52347bdSJani Nikula See Documentation/networking/ipv6.txt. 792e52347bdSJani Nikula 793e52347bdSJani Nikula disable_radix [PPC] 794e52347bdSJani Nikula Disable RADIX MMU mode on POWER9 795e52347bdSJani Nikula 796e52347bdSJani Nikula disable_cpu_apicid= [X86,APIC,SMP] 797e52347bdSJani Nikula Format: <int> 798e52347bdSJani Nikula The number of initial APIC ID for the 799e52347bdSJani Nikula corresponding CPU to be disabled at boot, 800e52347bdSJani Nikula mostly used for the kdump 2nd kernel to 801e52347bdSJani Nikula disable BSP to wake up multiple CPUs without 802e52347bdSJani Nikula causing system reset or hang due to sending 803e52347bdSJani Nikula INIT from AP to BSP. 804e52347bdSJani Nikula 805e52347bdSJani Nikula disable_ddw [PPC/PSERIES] 806e52347bdSJani Nikula Disable Dynamic DMA Window support. Use this if 807e52347bdSJani Nikula to workaround buggy firmware. 808e52347bdSJani Nikula 809e52347bdSJani Nikula disable_ipv6= [IPV6] 810e52347bdSJani Nikula See Documentation/networking/ipv6.txt. 811e52347bdSJani Nikula 812e52347bdSJani Nikula disable_mtrr_cleanup [X86] 813e52347bdSJani Nikula The kernel tries to adjust MTRR layout from continuous 814e52347bdSJani Nikula to discrete, to make X server driver able to add WB 815e52347bdSJani Nikula entry later. This parameter disables that. 816e52347bdSJani Nikula 817e52347bdSJani Nikula disable_mtrr_trim [X86, Intel and AMD only] 818e52347bdSJani Nikula By default the kernel will trim any uncacheable 819e52347bdSJani Nikula memory out of your available memory pool based on 820e52347bdSJani Nikula MTRR settings. This parameter disables that behavior, 821e52347bdSJani Nikula possibly causing your machine to run very slowly. 822e52347bdSJani Nikula 823e52347bdSJani Nikula disable_timer_pin_1 [X86] 824e52347bdSJani Nikula Disable PIN 1 of APIC timer 825e52347bdSJani Nikula Can be useful to work around chipset bugs. 826e52347bdSJani Nikula 827e52347bdSJani Nikula dis_ucode_ldr [X86] Disable the microcode loader. 828e52347bdSJani Nikula 829e52347bdSJani Nikula dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, 830e52347bdSJani Nikula this option disables the debugging code at boot. 831e52347bdSJani Nikula 832e52347bdSJani Nikula dma_debug_entries=<number> 833e52347bdSJani Nikula This option allows to tune the number of preallocated 834e52347bdSJani Nikula entries for DMA-API debugging code. One entry is 835e52347bdSJani Nikula required per DMA-API allocation. Use this if the 836e52347bdSJani Nikula DMA-API debugging code disables itself because the 837e52347bdSJani Nikula architectural default is too low. 838e52347bdSJani Nikula 839e52347bdSJani Nikula dma_debug_driver=<driver_name> 840e52347bdSJani Nikula With this option the DMA-API debugging driver 841e52347bdSJani Nikula filter feature can be enabled at boot time. Just 842e52347bdSJani Nikula pass the driver to filter for as the parameter. 843e52347bdSJani Nikula The filter can be disabled or changed to another 844e52347bdSJani Nikula driver later using sysfs. 845e52347bdSJani Nikula 846e52347bdSJani Nikula drm_kms_helper.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] 847e52347bdSJani Nikula Broken monitors, graphic adapters, KVMs and EDIDless 848e52347bdSJani Nikula panels may send no or incorrect EDID data sets. 849e52347bdSJani Nikula This parameter allows to specify an EDID data sets 850e52347bdSJani Nikula in the /lib/firmware directory that are used instead. 851e52347bdSJani Nikula Generic built-in EDID data sets are used, if one of 852e52347bdSJani Nikula edid/1024x768.bin, edid/1280x1024.bin, 853e52347bdSJani Nikula edid/1680x1050.bin, or edid/1920x1080.bin is given 854e52347bdSJani Nikula and no file with the same name exists. Details and 855e52347bdSJani Nikula instructions how to build your own EDID data are 856e52347bdSJani Nikula available in Documentation/EDID/HOWTO.txt. An EDID 857e52347bdSJani Nikula data set will only be used for a particular connector, 858e52347bdSJani Nikula if its name and a colon are prepended to the EDID 859e52347bdSJani Nikula name. Each connector may use a unique EDID data 860e52347bdSJani Nikula set by separating the files with a comma. An EDID 861e52347bdSJani Nikula data set with no connector name will be used for 862e52347bdSJani Nikula any connectors not explicitly specified. 863e52347bdSJani Nikula 864e52347bdSJani Nikula dscc4.setup= [NET] 865e52347bdSJani Nikula 866e7aa8c2eSLinus Torvalds dump_apple_properties [X86] 867e7aa8c2eSLinus Torvalds Dump name and content of EFI device properties on 868e7aa8c2eSLinus Torvalds x86 Macs. Useful for driver authors to determine 869e7aa8c2eSLinus Torvalds what data is available or for reverse-engineering. 870e7aa8c2eSLinus Torvalds 871e52347bdSJani Nikula dyndbg[="val"] [KNL,DYNAMIC_DEBUG] 872e52347bdSJani Nikula module.dyndbg[="val"] 873e52347bdSJani Nikula Enable debug messages at boot time. See 874e52347bdSJani Nikula Documentation/dynamic-debug-howto.txt for details. 875e52347bdSJani Nikula 876e52347bdSJani Nikula nompx [X86] Disables Intel Memory Protection Extensions. 877e52347bdSJani Nikula See Documentation/x86/intel_mpx.txt for more 878e52347bdSJani Nikula information about the feature. 879e52347bdSJani Nikula 880e52347bdSJani Nikula nopku [X86] Disable Memory Protection Keys CPU feature found 881e52347bdSJani Nikula in some Intel CPUs. 882e52347bdSJani Nikula 883e52347bdSJani Nikula module.async_probe [KNL] 884e52347bdSJani Nikula Enable asynchronous probe on this module. 885e52347bdSJani Nikula 886e52347bdSJani Nikula early_ioremap_debug [KNL] 887e52347bdSJani Nikula Enable debug messages in early_ioremap support. This 888e52347bdSJani Nikula is useful for tracking down temporary early mappings 889e52347bdSJani Nikula which are not unmapped. 890e52347bdSJani Nikula 891e52347bdSJani Nikula earlycon= [KNL] Output early console device and options. 892e52347bdSJani Nikula 893e52347bdSJani Nikula When used with no options, the early console is 894e52347bdSJani Nikula determined by the stdout-path property in device 895e52347bdSJani Nikula tree's chosen node. 896e52347bdSJani Nikula 897e52347bdSJani Nikula cdns,<addr>[,options] 898e52347bdSJani Nikula Start an early, polled-mode console on a Cadence 899e52347bdSJani Nikula (xuartps) serial port at the specified address. Only 900e52347bdSJani Nikula supported option is baud rate. If baud rate is not 901e52347bdSJani Nikula specified, the serial port must already be setup and 902e52347bdSJani Nikula configured. 903e52347bdSJani Nikula 904e52347bdSJani Nikula uart[8250],io,<addr>[,options] 905e52347bdSJani Nikula uart[8250],mmio,<addr>[,options] 906e52347bdSJani Nikula uart[8250],mmio32,<addr>[,options] 907e52347bdSJani Nikula uart[8250],mmio32be,<addr>[,options] 908e52347bdSJani Nikula uart[8250],0x<addr>[,options] 909e52347bdSJani Nikula Start an early, polled-mode console on the 8250/16550 910e52347bdSJani Nikula UART at the specified I/O port or MMIO address. 911e52347bdSJani Nikula MMIO inter-register address stride is either 8-bit 912e52347bdSJani Nikula (mmio) or 32-bit (mmio32 or mmio32be). 913e52347bdSJani Nikula If none of [io|mmio|mmio32|mmio32be], <addr> is assumed 914e52347bdSJani Nikula to be equivalent to 'mmio'. 'options' are specified 915e52347bdSJani Nikula in the same format described for "console=ttyS<n>"; if 916e52347bdSJani Nikula unspecified, the h/w is not initialized. 917e52347bdSJani Nikula 918e52347bdSJani Nikula pl011,<addr> 919e52347bdSJani Nikula pl011,mmio32,<addr> 920e52347bdSJani Nikula Start an early, polled-mode console on a pl011 serial 921e52347bdSJani Nikula port at the specified address. The pl011 serial port 922e52347bdSJani Nikula must already be setup and configured. Options are not 923e52347bdSJani Nikula yet supported. If 'mmio32' is specified, then only 924e52347bdSJani Nikula the driver will use only 32-bit accessors to read/write 925e52347bdSJani Nikula the device registers. 926e52347bdSJani Nikula 927e52347bdSJani Nikula meson,<addr> 928e52347bdSJani Nikula Start an early, polled-mode console on a meson serial 929e52347bdSJani Nikula port at the specified address. The serial port must 930e52347bdSJani Nikula already be setup and configured. Options are not yet 931e52347bdSJani Nikula supported. 932e52347bdSJani Nikula 933e52347bdSJani Nikula msm_serial,<addr> 934e52347bdSJani Nikula Start an early, polled-mode console on an msm serial 935e52347bdSJani Nikula port at the specified address. The serial port 936e52347bdSJani Nikula must already be setup and configured. Options are not 937e52347bdSJani Nikula yet supported. 938e52347bdSJani Nikula 939e52347bdSJani Nikula msm_serial_dm,<addr> 940e52347bdSJani Nikula Start an early, polled-mode console on an msm serial 941e52347bdSJani Nikula dm port at the specified address. The serial port 942e52347bdSJani Nikula must already be setup and configured. Options are not 943e52347bdSJani Nikula yet supported. 944e52347bdSJani Nikula 945e52347bdSJani Nikula smh Use ARM semihosting calls for early console. 946e52347bdSJani Nikula 947e52347bdSJani Nikula s3c2410,<addr> 948e52347bdSJani Nikula s3c2412,<addr> 949e52347bdSJani Nikula s3c2440,<addr> 950e52347bdSJani Nikula s3c6400,<addr> 951e52347bdSJani Nikula s5pv210,<addr> 952e52347bdSJani Nikula exynos4210,<addr> 953e52347bdSJani Nikula Use early console provided by serial driver available 954e52347bdSJani Nikula on Samsung SoCs, requires selecting proper type and 955e52347bdSJani Nikula a correct base address of the selected UART port. The 956e52347bdSJani Nikula serial port must already be setup and configured. 957e52347bdSJani Nikula Options are not yet supported. 958e52347bdSJani Nikula 959e52347bdSJani Nikula lpuart,<addr> 960e52347bdSJani Nikula lpuart32,<addr> 961e52347bdSJani Nikula Use early console provided by Freescale LP UART driver 962e52347bdSJani Nikula found on Freescale Vybrid and QorIQ LS1021A processors. 963e52347bdSJani Nikula A valid base address must be provided, and the serial 964e52347bdSJani Nikula port must already be setup and configured. 965e52347bdSJani Nikula 966e52347bdSJani Nikula armada3700_uart,<addr> 967e52347bdSJani Nikula Start an early, polled-mode console on the 968e52347bdSJani Nikula Armada 3700 serial port at the specified 969e52347bdSJani Nikula address. The serial port must already be setup 970e52347bdSJani Nikula and configured. Options are not yet supported. 971e52347bdSJani Nikula 972e52347bdSJani Nikula earlyprintk= [X86,SH,BLACKFIN,ARM,M68k] 973e52347bdSJani Nikula earlyprintk=vga 974e52347bdSJani Nikula earlyprintk=efi 975e52347bdSJani Nikula earlyprintk=xen 976e52347bdSJani Nikula earlyprintk=serial[,ttySn[,baudrate]] 977e52347bdSJani Nikula earlyprintk=serial[,0x...[,baudrate]] 978e52347bdSJani Nikula earlyprintk=ttySn[,baudrate] 979e52347bdSJani Nikula earlyprintk=dbgp[debugController#] 980e52347bdSJani Nikula earlyprintk=pciserial,bus:device.function[,baudrate] 981e52347bdSJani Nikula 982e52347bdSJani Nikula earlyprintk is useful when the kernel crashes before 983e52347bdSJani Nikula the normal console is initialized. It is not enabled by 984e52347bdSJani Nikula default because it has some cosmetic problems. 985e52347bdSJani Nikula 986e52347bdSJani Nikula Append ",keep" to not disable it when the real console 987e52347bdSJani Nikula takes over. 988e52347bdSJani Nikula 989e52347bdSJani Nikula Only one of vga, efi, serial, or usb debug port can 990e52347bdSJani Nikula be used at a time. 991e52347bdSJani Nikula 992e52347bdSJani Nikula Currently only ttyS0 and ttyS1 may be specified by 993e52347bdSJani Nikula name. Other I/O ports may be explicitly specified 994e52347bdSJani Nikula on some architectures (x86 and arm at least) by 995e52347bdSJani Nikula replacing ttySn with an I/O port address, like this: 996e52347bdSJani Nikula earlyprintk=serial,0x1008,115200 997e52347bdSJani Nikula You can find the port for a given device in 998e52347bdSJani Nikula /proc/tty/driver/serial: 999e52347bdSJani Nikula 2: uart:ST16650V2 port:00001008 irq:18 ... 1000e52347bdSJani Nikula 1001e52347bdSJani Nikula Interaction with the standard serial driver is not 1002e52347bdSJani Nikula very good. 1003e52347bdSJani Nikula 1004e52347bdSJani Nikula The VGA and EFI output is eventually overwritten by 1005e52347bdSJani Nikula the real console. 1006e52347bdSJani Nikula 1007e52347bdSJani Nikula The xen output can only be used by Xen PV guests. 1008e52347bdSJani Nikula 1009e52347bdSJani Nikula edac_report= [HW,EDAC] Control how to report EDAC event 1010e52347bdSJani Nikula Format: {"on" | "off" | "force"} 1011e52347bdSJani Nikula on: enable EDAC to report H/W event. May be overridden 1012e52347bdSJani Nikula by other higher priority error reporting module. 1013e52347bdSJani Nikula off: disable H/W event reporting through EDAC. 1014e52347bdSJani Nikula force: enforce the use of EDAC to report H/W event. 1015e52347bdSJani Nikula default: on. 1016e52347bdSJani Nikula 1017e52347bdSJani Nikula ekgdboc= [X86,KGDB] Allow early kernel console debugging 1018e52347bdSJani Nikula ekgdboc=kbd 1019e52347bdSJani Nikula 1020e52347bdSJani Nikula This is designed to be used in conjunction with 1021e52347bdSJani Nikula the boot argument: earlyprintk=vga 1022e52347bdSJani Nikula 1023e52347bdSJani Nikula edd= [EDD] 1024e52347bdSJani Nikula Format: {"off" | "on" | "skip[mbr]"} 1025e52347bdSJani Nikula 1026e52347bdSJani Nikula efi= [EFI] 1027e52347bdSJani Nikula Format: { "old_map", "nochunk", "noruntime", "debug" } 1028e52347bdSJani Nikula old_map [X86-64]: switch to the old ioremap-based EFI 1029e52347bdSJani Nikula runtime services mapping. 32-bit still uses this one by 1030e52347bdSJani Nikula default. 1031e52347bdSJani Nikula nochunk: disable reading files in "chunks" in the EFI 1032e52347bdSJani Nikula boot stub, as chunking can cause problems with some 1033e52347bdSJani Nikula firmware implementations. 1034e52347bdSJani Nikula noruntime : disable EFI runtime services support 1035e52347bdSJani Nikula debug: enable misc debug output 1036e52347bdSJani Nikula 1037e52347bdSJani Nikula efi_no_storage_paranoia [EFI; X86] 1038e52347bdSJani Nikula Using this parameter you can use more than 50% of 1039e52347bdSJani Nikula your efi variable storage. Use this parameter only if 1040e52347bdSJani Nikula you are really sure that your UEFI does sane gc and 1041e52347bdSJani Nikula fulfills the spec otherwise your board may brick. 1042e52347bdSJani Nikula 1043e52347bdSJani Nikula efi_fake_mem= nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86] 1044e52347bdSJani Nikula Add arbitrary attribute to specific memory range by 1045e52347bdSJani Nikula updating original EFI memory map. 1046e52347bdSJani Nikula Region of memory which aa attribute is added to is 1047e52347bdSJani Nikula from ss to ss+nn. 1048e52347bdSJani Nikula If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000 1049e52347bdSJani Nikula is specified, EFI_MEMORY_MORE_RELIABLE(0x10000) 1050e52347bdSJani Nikula attribute is added to range 0x100000000-0x180000000 and 1051e52347bdSJani Nikula 0x10a0000000-0x1120000000. 1052e52347bdSJani Nikula 1053e52347bdSJani Nikula Using this parameter you can do debugging of EFI memmap 1054e52347bdSJani Nikula related feature. For example, you can do debugging of 1055e52347bdSJani Nikula Address Range Mirroring feature even if your box 1056e52347bdSJani Nikula doesn't support it. 1057e52347bdSJani Nikula 1058e52347bdSJani Nikula efivar_ssdt= [EFI; X86] Name of an EFI variable that contains an SSDT 1059e52347bdSJani Nikula that is to be dynamically loaded by Linux. If there are 1060e52347bdSJani Nikula multiple variables with the same name but with different 1061e52347bdSJani Nikula vendor GUIDs, all of them will be loaded. See 1062e52347bdSJani Nikula Documentation/acpi/ssdt-overlays.txt for details. 1063e52347bdSJani Nikula 1064e52347bdSJani Nikula 1065e52347bdSJani Nikula eisa_irq_edge= [PARISC,HW] 1066e52347bdSJani Nikula See header of drivers/parisc/eisa.c. 1067e52347bdSJani Nikula 1068e52347bdSJani Nikula elanfreq= [X86-32] 1069e52347bdSJani Nikula See comment before function elanfreq_setup() in 1070e52347bdSJani Nikula arch/x86/kernel/cpu/cpufreq/elanfreq.c. 1071e52347bdSJani Nikula 1072e52347bdSJani Nikula elevator= [IOSCHED] 1073e52347bdSJani Nikula Format: {"cfq" | "deadline" | "noop"} 1074e52347bdSJani Nikula See Documentation/block/cfq-iosched.txt and 1075e52347bdSJani Nikula Documentation/block/deadline-iosched.txt for details. 1076e52347bdSJani Nikula 1077e52347bdSJani Nikula elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390] 1078e52347bdSJani Nikula Specifies physical address of start of kernel core 1079e52347bdSJani Nikula image elf header and optionally the size. Generally 1080e52347bdSJani Nikula kexec loader will pass this option to capture kernel. 1081e52347bdSJani Nikula See Documentation/kdump/kdump.txt for details. 1082e52347bdSJani Nikula 1083e52347bdSJani Nikula enable_mtrr_cleanup [X86] 1084e52347bdSJani Nikula The kernel tries to adjust MTRR layout from continuous 1085e52347bdSJani Nikula to discrete, to make X server driver able to add WB 1086e52347bdSJani Nikula entry later. This parameter enables that. 1087e52347bdSJani Nikula 1088e52347bdSJani Nikula enable_timer_pin_1 [X86] 1089e52347bdSJani Nikula Enable PIN 1 of APIC timer 1090e52347bdSJani Nikula Can be useful to work around chipset bugs 1091e52347bdSJani Nikula (in particular on some ATI chipsets). 1092e52347bdSJani Nikula The kernel tries to set a reasonable default. 1093e52347bdSJani Nikula 1094e52347bdSJani Nikula enforcing [SELINUX] Set initial enforcing status. 1095e52347bdSJani Nikula Format: {"0" | "1"} 1096e52347bdSJani Nikula See security/selinux/Kconfig help text. 1097e52347bdSJani Nikula 0 -- permissive (log only, no denials). 1098e52347bdSJani Nikula 1 -- enforcing (deny and log). 1099e52347bdSJani Nikula Default value is 0. 1100e52347bdSJani Nikula Value can be changed at runtime via /selinux/enforce. 1101e52347bdSJani Nikula 1102e52347bdSJani Nikula erst_disable [ACPI] 1103e52347bdSJani Nikula Disable Error Record Serialization Table (ERST) 1104e52347bdSJani Nikula support. 1105e52347bdSJani Nikula 1106e52347bdSJani Nikula ether= [HW,NET] Ethernet cards parameters 1107e52347bdSJani Nikula This option is obsoleted by the "netdev=" option, which 1108e52347bdSJani Nikula has equivalent usage. See its documentation for details. 1109e52347bdSJani Nikula 1110e52347bdSJani Nikula evm= [EVM] 1111e52347bdSJani Nikula Format: { "fix" } 1112e52347bdSJani Nikula Permit 'security.evm' to be updated regardless of 1113e52347bdSJani Nikula current integrity status. 1114e52347bdSJani Nikula 1115e52347bdSJani Nikula failslab= 1116e52347bdSJani Nikula fail_page_alloc= 1117e52347bdSJani Nikula fail_make_request=[KNL] 1118e52347bdSJani Nikula General fault injection mechanism. 1119e52347bdSJani Nikula Format: <interval>,<probability>,<space>,<times> 1120e52347bdSJani Nikula See also Documentation/fault-injection/. 1121e52347bdSJani Nikula 1122e52347bdSJani Nikula floppy= [HW] 1123e52347bdSJani Nikula See Documentation/blockdev/floppy.txt. 1124e52347bdSJani Nikula 1125e52347bdSJani Nikula force_pal_cache_flush 1126e52347bdSJani Nikula [IA-64] Avoid check_sal_cache_flush which may hang on 1127e52347bdSJani Nikula buggy SAL_CACHE_FLUSH implementations. Using this 1128e52347bdSJani Nikula parameter will force ia64_sal_cache_flush to call 1129e52347bdSJani Nikula ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. 1130e52347bdSJani Nikula 1131e52347bdSJani Nikula forcepae [X86-32] 1132e52347bdSJani Nikula Forcefully enable Physical Address Extension (PAE). 1133e52347bdSJani Nikula Many Pentium M systems disable PAE but may have a 1134e52347bdSJani Nikula functionally usable PAE implementation. 1135e52347bdSJani Nikula Warning: use of this parameter will taint the kernel 1136e52347bdSJani Nikula and may cause unknown problems. 1137e52347bdSJani Nikula 1138e52347bdSJani Nikula ftrace=[tracer] 1139e52347bdSJani Nikula [FTRACE] will set and start the specified tracer 1140e52347bdSJani Nikula as early as possible in order to facilitate early 1141e52347bdSJani Nikula boot debugging. 1142e52347bdSJani Nikula 1143e52347bdSJani Nikula ftrace_dump_on_oops[=orig_cpu] 1144e52347bdSJani Nikula [FTRACE] will dump the trace buffers on oops. 1145e52347bdSJani Nikula If no parameter is passed, ftrace will dump 1146e52347bdSJani Nikula buffers of all CPUs, but if you pass orig_cpu, it will 1147e52347bdSJani Nikula dump only the buffer of the CPU that triggered the 1148e52347bdSJani Nikula oops. 1149e52347bdSJani Nikula 1150e52347bdSJani Nikula ftrace_filter=[function-list] 1151e52347bdSJani Nikula [FTRACE] Limit the functions traced by the function 1152e52347bdSJani Nikula tracer at boot up. function-list is a comma separated 1153e52347bdSJani Nikula list of functions. This list can be changed at run 1154e52347bdSJani Nikula time by the set_ftrace_filter file in the debugfs 1155e52347bdSJani Nikula tracing directory. 1156e52347bdSJani Nikula 1157e52347bdSJani Nikula ftrace_notrace=[function-list] 1158e52347bdSJani Nikula [FTRACE] Do not trace the functions specified in 1159e52347bdSJani Nikula function-list. This list can be changed at run time 1160e52347bdSJani Nikula by the set_ftrace_notrace file in the debugfs 1161e52347bdSJani Nikula tracing directory. 1162e52347bdSJani Nikula 1163e52347bdSJani Nikula ftrace_graph_filter=[function-list] 1164e52347bdSJani Nikula [FTRACE] Limit the top level callers functions traced 1165e52347bdSJani Nikula by the function graph tracer at boot up. 1166e52347bdSJani Nikula function-list is a comma separated list of functions 1167e52347bdSJani Nikula that can be changed at run time by the 1168e52347bdSJani Nikula set_graph_function file in the debugfs tracing directory. 1169e52347bdSJani Nikula 1170e52347bdSJani Nikula ftrace_graph_notrace=[function-list] 1171e52347bdSJani Nikula [FTRACE] Do not trace from the functions specified in 1172e52347bdSJani Nikula function-list. This list is a comma separated list of 1173e52347bdSJani Nikula functions that can be changed at run time by the 1174e52347bdSJani Nikula set_graph_notrace file in the debugfs tracing directory. 1175e52347bdSJani Nikula 1176e52347bdSJani Nikula gamecon.map[2|3]= 1177e52347bdSJani Nikula [HW,JOY] Multisystem joystick and NES/SNES/PSX pad 1178e52347bdSJani Nikula support via parallel port (up to 5 devices per port) 1179e52347bdSJani Nikula Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> 1180e52347bdSJani Nikula See also Documentation/input/joystick-parport.txt 1181e52347bdSJani Nikula 1182e52347bdSJani Nikula gamma= [HW,DRM] 1183e52347bdSJani Nikula 1184e52347bdSJani Nikula gart_fix_e820= [X86_64] disable the fix e820 for K8 GART 1185e52347bdSJani Nikula Format: off | on 1186e52347bdSJani Nikula default: on 1187e52347bdSJani Nikula 1188e52347bdSJani Nikula gcov_persist= [GCOV] When non-zero (default), profiling data for 1189e52347bdSJani Nikula kernel modules is saved and remains accessible via 1190e52347bdSJani Nikula debugfs, even when the module is unloaded/reloaded. 1191e52347bdSJani Nikula When zero, profiling data is discarded and associated 1192e52347bdSJani Nikula debugfs files are removed at module unload time. 1193e52347bdSJani Nikula 1194e52347bdSJani Nikula gpt [EFI] Forces disk with valid GPT signature but 1195e52347bdSJani Nikula invalid Protective MBR to be treated as GPT. If the 1196e52347bdSJani Nikula primary GPT is corrupted, it enables the backup/alternate 1197e52347bdSJani Nikula GPT to be used instead. 1198e52347bdSJani Nikula 1199e52347bdSJani Nikula grcan.enable0= [HW] Configuration of physical interface 0. Determines 1200e52347bdSJani Nikula the "Enable 0" bit of the configuration register. 1201e52347bdSJani Nikula Format: 0 | 1 1202e52347bdSJani Nikula Default: 0 1203e52347bdSJani Nikula grcan.enable1= [HW] Configuration of physical interface 1. Determines 1204e52347bdSJani Nikula the "Enable 0" bit of the configuration register. 1205e52347bdSJani Nikula Format: 0 | 1 1206e52347bdSJani Nikula Default: 0 1207e52347bdSJani Nikula grcan.select= [HW] Select which physical interface to use. 1208e52347bdSJani Nikula Format: 0 | 1 1209e52347bdSJani Nikula Default: 0 1210e52347bdSJani Nikula grcan.txsize= [HW] Sets the size of the tx buffer. 1211e52347bdSJani Nikula Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0. 1212e52347bdSJani Nikula Default: 1024 1213e52347bdSJani Nikula grcan.rxsize= [HW] Sets the size of the rx buffer. 1214e52347bdSJani Nikula Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. 1215e52347bdSJani Nikula Default: 1024 1216e52347bdSJani Nikula 1217e52347bdSJani Nikula gpio-mockup.gpio_mockup_ranges 1218e52347bdSJani Nikula [HW] Sets the ranges of gpiochip of for this device. 1219e52347bdSJani Nikula Format: <start1>,<end1>,<start2>,<end2>... 1220e52347bdSJani Nikula 1221e52347bdSJani Nikula hardlockup_all_cpu_backtrace= 1222e52347bdSJani Nikula [KNL] Should the hard-lockup detector generate 1223e52347bdSJani Nikula backtraces on all cpus. 1224e52347bdSJani Nikula Format: <integer> 1225e52347bdSJani Nikula 1226e52347bdSJani Nikula hashdist= [KNL,NUMA] Large hashes allocated during boot 1227e52347bdSJani Nikula are distributed across NUMA nodes. Defaults on 1228e52347bdSJani Nikula for 64-bit NUMA, off otherwise. 1229e52347bdSJani Nikula Format: 0 | 1 (for off | on) 1230e52347bdSJani Nikula 1231e52347bdSJani Nikula hcl= [IA-64] SGI's Hardware Graph compatibility layer 1232e52347bdSJani Nikula 1233e52347bdSJani Nikula hd= [EIDE] (E)IDE hard drive subsystem geometry 1234e52347bdSJani Nikula Format: <cyl>,<head>,<sect> 1235e52347bdSJani Nikula 1236e52347bdSJani Nikula hest_disable [ACPI] 1237e52347bdSJani Nikula Disable Hardware Error Source Table (HEST) support; 1238e52347bdSJani Nikula corresponding firmware-first mode error processing 1239e52347bdSJani Nikula logic will be disabled. 1240e52347bdSJani Nikula 1241e52347bdSJani Nikula highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact 1242e52347bdSJani Nikula size of <nn>. This works even on boxes that have no 1243e52347bdSJani Nikula highmem otherwise. This also works to reduce highmem 1244e52347bdSJani Nikula size on bigger boxes. 1245e52347bdSJani Nikula 1246e52347bdSJani Nikula highres= [KNL] Enable/disable high resolution timer mode. 1247e52347bdSJani Nikula Valid parameters: "on", "off" 1248e52347bdSJani Nikula Default: "on" 1249e52347bdSJani Nikula 1250e52347bdSJani Nikula hisax= [HW,ISDN] 1251e52347bdSJani Nikula See Documentation/isdn/README.HiSax. 1252e52347bdSJani Nikula 1253e52347bdSJani Nikula hlt [BUGS=ARM,SH] 1254e52347bdSJani Nikula 1255e52347bdSJani Nikula hpet= [X86-32,HPET] option to control HPET usage 1256e52347bdSJani Nikula Format: { enable (default) | disable | force | 1257e52347bdSJani Nikula verbose } 1258e52347bdSJani Nikula disable: disable HPET and use PIT instead 1259e52347bdSJani Nikula force: allow force enabled of undocumented chips (ICH4, 1260e52347bdSJani Nikula VIA, nVidia) 1261e52347bdSJani Nikula verbose: show contents of HPET registers during setup 1262e52347bdSJani Nikula 1263e52347bdSJani Nikula hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET 1264e52347bdSJani Nikula registers. Default set by CONFIG_HPET_MMAP_DEFAULT. 1265e52347bdSJani Nikula 1266e52347bdSJani Nikula hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. 1267e52347bdSJani Nikula hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. 1268e52347bdSJani Nikula On x86-64 and powerpc, this option can be specified 1269e52347bdSJani Nikula multiple times interleaved with hugepages= to reserve 1270e52347bdSJani Nikula huge pages of different sizes. Valid pages sizes on 1271e52347bdSJani Nikula x86-64 are 2M (when the CPU supports "pse") and 1G 1272e52347bdSJani Nikula (when the CPU supports the "pdpe1gb" cpuinfo flag). 1273e52347bdSJani Nikula 1274e52347bdSJani Nikula hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) 1275e52347bdSJani Nikula terminal devices. Valid values: 0..8 1276e52347bdSJani Nikula hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. 1277e52347bdSJani Nikula If specified, z/VM IUCV HVC accepts connections 1278e52347bdSJani Nikula from listed z/VM user IDs only. 1279e52347bdSJani Nikula 1280e52347bdSJani Nikula hwthread_map= [METAG] Comma-separated list of Linux cpu id to 1281e52347bdSJani Nikula hardware thread id mappings. 1282e52347bdSJani Nikula Format: <cpu>:<hwthread> 1283e52347bdSJani Nikula 1284e52347bdSJani Nikula keep_bootcon [KNL] 1285e52347bdSJani Nikula Do not unregister boot console at start. This is only 1286e52347bdSJani Nikula useful for debugging when something happens in the window 1287e52347bdSJani Nikula between unregistering the boot console and initializing 1288e52347bdSJani Nikula the real console. 1289e52347bdSJani Nikula 1290e52347bdSJani Nikula i2c_bus= [HW] Override the default board specific I2C bus speed 1291e52347bdSJani Nikula or register an additional I2C bus that is not 1292e52347bdSJani Nikula registered from board initialization code. 1293e52347bdSJani Nikula Format: 1294e52347bdSJani Nikula <bus_id>,<clkrate> 1295e52347bdSJani Nikula 1296e52347bdSJani Nikula i8042.debug [HW] Toggle i8042 debug mode 1297e52347bdSJani Nikula i8042.unmask_kbd_data 1298e52347bdSJani Nikula [HW] Enable printing of interrupt data from the KBD port 1299e52347bdSJani Nikula (disabled by default, and as a pre-condition 1300e52347bdSJani Nikula requires that i8042.debug=1 be enabled) 1301e52347bdSJani Nikula i8042.direct [HW] Put keyboard port into non-translated mode 1302e52347bdSJani Nikula i8042.dumbkbd [HW] Pretend that controller can only read data from 1303e52347bdSJani Nikula keyboard and cannot control its state 1304e52347bdSJani Nikula (Don't attempt to blink the leds) 1305e52347bdSJani Nikula i8042.noaux [HW] Don't check for auxiliary (== mouse) port 1306e52347bdSJani Nikula i8042.nokbd [HW] Don't check/create keyboard port 1307e52347bdSJani Nikula i8042.noloop [HW] Disable the AUX Loopback command while probing 1308e52347bdSJani Nikula for the AUX port 1309e52347bdSJani Nikula i8042.nomux [HW] Don't check presence of an active multiplexing 1310e52347bdSJani Nikula controller 1311e52347bdSJani Nikula i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX 1312e52347bdSJani Nikula controllers 1313e52347bdSJani Nikula i8042.notimeout [HW] Ignore timeout condition signalled by controller 1314e52347bdSJani Nikula i8042.reset [HW] Reset the controller during init, cleanup and 1315e52347bdSJani Nikula suspend-to-ram transitions, only during s2r 1316e52347bdSJani Nikula transitions, or never reset 1317e52347bdSJani Nikula Format: { 1 | Y | y | 0 | N | n } 1318e52347bdSJani Nikula 1, Y, y: always reset controller 1319e52347bdSJani Nikula 0, N, n: don't ever reset controller 1320e52347bdSJani Nikula Default: only on s2r transitions on x86; most other 1321e52347bdSJani Nikula architectures force reset to be always executed 1322e52347bdSJani Nikula i8042.unlock [HW] Unlock (ignore) the keylock 1323e52347bdSJani Nikula i8042.kbdreset [HW] Reset device connected to KBD port 1324e52347bdSJani Nikula 1325e52347bdSJani Nikula i810= [HW,DRM] 1326e52347bdSJani Nikula 1327e52347bdSJani Nikula i8k.ignore_dmi [HW] Continue probing hardware even if DMI data 1328e52347bdSJani Nikula indicates that the driver is running on unsupported 1329e52347bdSJani Nikula hardware. 1330e52347bdSJani Nikula i8k.force [HW] Activate i8k driver even if SMM BIOS signature 1331e52347bdSJani Nikula does not match list of supported models. 1332e52347bdSJani Nikula i8k.power_status 1333e52347bdSJani Nikula [HW] Report power status in /proc/i8k 1334e52347bdSJani Nikula (disabled by default) 1335e52347bdSJani Nikula i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN 1336e52347bdSJani Nikula capability is set. 1337e52347bdSJani Nikula 1338e52347bdSJani Nikula i915.invert_brightness= 1339e52347bdSJani Nikula [DRM] Invert the sense of the variable that is used to 1340e52347bdSJani Nikula set the brightness of the panel backlight. Normally a 1341e52347bdSJani Nikula brightness value of 0 indicates backlight switched off, 1342e52347bdSJani Nikula and the maximum of the brightness value sets the backlight 1343e52347bdSJani Nikula to maximum brightness. If this parameter is set to 0 1344e52347bdSJani Nikula (default) and the machine requires it, or this parameter 1345e52347bdSJani Nikula is set to 1, a brightness value of 0 sets the backlight 1346e52347bdSJani Nikula to maximum brightness, and the maximum of the brightness 1347e52347bdSJani Nikula value switches the backlight off. 1348e52347bdSJani Nikula -1 -- never invert brightness 1349e52347bdSJani Nikula 0 -- machine default 1350e52347bdSJani Nikula 1 -- force brightness inversion 1351e52347bdSJani Nikula 1352e52347bdSJani Nikula icn= [HW,ISDN] 1353e52347bdSJani Nikula Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] 1354e52347bdSJani Nikula 1355e52347bdSJani Nikula ide-core.nodma= [HW] (E)IDE subsystem 1356e52347bdSJani Nikula Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc 1357e52347bdSJani Nikula .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr 1358e52347bdSJani Nikula .cdrom .chs .ignore_cable are additional options 1359e52347bdSJani Nikula See Documentation/ide/ide.txt. 1360e52347bdSJani Nikula 1361e52347bdSJani Nikula ide-generic.probe-mask= [HW] (E)IDE subsystem 1362e52347bdSJani Nikula Format: <int> 1363e52347bdSJani Nikula Probe mask for legacy ISA IDE ports. Depending on 1364e52347bdSJani Nikula platform up to 6 ports are supported, enabled by 1365e52347bdSJani Nikula setting corresponding bits in the mask to 1. The 1366e52347bdSJani Nikula default value is 0x0, which has a special meaning. 1367e52347bdSJani Nikula On systems that have PCI, it triggers scanning the 1368e52347bdSJani Nikula PCI bus for the first and the second port, which 1369e52347bdSJani Nikula are then probed. On systems without PCI the value 1370e52347bdSJani Nikula of 0x0 enables probing the two first ports as if it 1371e52347bdSJani Nikula was 0x3. 1372e52347bdSJani Nikula 1373e52347bdSJani Nikula ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem 1374e52347bdSJani Nikula Claim all unknown PCI IDE storage controllers. 1375e52347bdSJani Nikula 1376e52347bdSJani Nikula idle= [X86] 1377e52347bdSJani Nikula Format: idle=poll, idle=halt, idle=nomwait 1378e52347bdSJani Nikula Poll forces a polling idle loop that can slightly 1379e52347bdSJani Nikula improve the performance of waking up a idle CPU, but 1380e52347bdSJani Nikula will use a lot of power and make the system run hot. 1381e52347bdSJani Nikula Not recommended. 1382e52347bdSJani Nikula idle=halt: Halt is forced to be used for CPU idle. 1383e52347bdSJani Nikula In such case C2/C3 won't be used again. 1384e52347bdSJani Nikula idle=nomwait: Disable mwait for CPU C-states 1385e52347bdSJani Nikula 1386e52347bdSJani Nikula ieee754= [MIPS] Select IEEE Std 754 conformance mode 1387e52347bdSJani Nikula Format: { strict | legacy | 2008 | relaxed } 1388e52347bdSJani Nikula Default: strict 1389e52347bdSJani Nikula 1390e52347bdSJani Nikula Choose which programs will be accepted for execution 1391e52347bdSJani Nikula based on the IEEE 754 NaN encoding(s) supported by 1392e52347bdSJani Nikula the FPU and the NaN encoding requested with the value 1393e52347bdSJani Nikula of an ELF file header flag individually set by each 1394e52347bdSJani Nikula binary. Hardware implementations are permitted to 1395e52347bdSJani Nikula support either or both of the legacy and the 2008 NaN 1396e52347bdSJani Nikula encoding mode. 1397e52347bdSJani Nikula 1398e52347bdSJani Nikula Available settings are as follows: 1399e52347bdSJani Nikula strict accept binaries that request a NaN encoding 1400e52347bdSJani Nikula supported by the FPU 1401e52347bdSJani Nikula legacy only accept legacy-NaN binaries, if supported 1402e52347bdSJani Nikula by the FPU 1403e52347bdSJani Nikula 2008 only accept 2008-NaN binaries, if supported 1404e52347bdSJani Nikula by the FPU 1405e52347bdSJani Nikula relaxed accept any binaries regardless of whether 1406e52347bdSJani Nikula supported by the FPU 1407e52347bdSJani Nikula 1408e52347bdSJani Nikula The FPU emulator is always able to support both NaN 1409e52347bdSJani Nikula encodings, so if no FPU hardware is present or it has 1410e52347bdSJani Nikula been disabled with 'nofpu', then the settings of 1411e52347bdSJani Nikula 'legacy' and '2008' strap the emulator accordingly, 1412e52347bdSJani Nikula 'relaxed' straps the emulator for both legacy-NaN and 1413e52347bdSJani Nikula 2008-NaN, whereas 'strict' enables legacy-NaN only on 1414e52347bdSJani Nikula legacy processors and both NaN encodings on MIPS32 or 1415e52347bdSJani Nikula MIPS64 CPUs. 1416e52347bdSJani Nikula 1417e52347bdSJani Nikula The setting for ABS.fmt/NEG.fmt instruction execution 1418e52347bdSJani Nikula mode generally follows that for the NaN encoding, 1419e52347bdSJani Nikula except where unsupported by hardware. 1420e52347bdSJani Nikula 1421e52347bdSJani Nikula ignore_loglevel [KNL] 1422e52347bdSJani Nikula Ignore loglevel setting - this will print /all/ 1423e52347bdSJani Nikula kernel messages to the console. Useful for debugging. 1424e52347bdSJani Nikula We also add it as printk module parameter, so users 1425e52347bdSJani Nikula could change it dynamically, usually by 1426e52347bdSJani Nikula /sys/module/printk/parameters/ignore_loglevel. 1427e52347bdSJani Nikula 1428e52347bdSJani Nikula ignore_rlimit_data 1429e52347bdSJani Nikula Ignore RLIMIT_DATA setting for data mappings, 1430e52347bdSJani Nikula print warning at first misuse. Can be changed via 1431e52347bdSJani Nikula /sys/module/kernel/parameters/ignore_rlimit_data. 1432e52347bdSJani Nikula 1433e52347bdSJani Nikula ihash_entries= [KNL] 1434e52347bdSJani Nikula Set number of hash buckets for inode cache. 1435e52347bdSJani Nikula 1436e52347bdSJani Nikula ima_appraise= [IMA] appraise integrity measurements 1437e52347bdSJani Nikula Format: { "off" | "enforce" | "fix" | "log" } 1438e52347bdSJani Nikula default: "enforce" 1439e52347bdSJani Nikula 1440e52347bdSJani Nikula ima_appraise_tcb [IMA] 1441e52347bdSJani Nikula The builtin appraise policy appraises all files 1442e52347bdSJani Nikula owned by uid=0. 1443e52347bdSJani Nikula 1444e52347bdSJani Nikula ima_hash= [IMA] 1445e52347bdSJani Nikula Format: { md5 | sha1 | rmd160 | sha256 | sha384 1446e52347bdSJani Nikula | sha512 | ... } 1447e52347bdSJani Nikula default: "sha1" 1448e52347bdSJani Nikula 1449e52347bdSJani Nikula The list of supported hash algorithms is defined 1450e52347bdSJani Nikula in crypto/hash_info.h. 1451e52347bdSJani Nikula 1452e52347bdSJani Nikula ima_policy= [IMA] 1453e52347bdSJani Nikula The builtin measurement policy to load during IMA 1454e52347bdSJani Nikula setup. Specyfing "tcb" as the value, measures all 1455e52347bdSJani Nikula programs exec'd, files mmap'd for exec, and all files 1456e52347bdSJani Nikula opened with the read mode bit set by either the 1457e52347bdSJani Nikula effective uid (euid=0) or uid=0. 1458e52347bdSJani Nikula Format: "tcb" 1459e52347bdSJani Nikula 1460e52347bdSJani Nikula ima_tcb [IMA] Deprecated. Use ima_policy= instead. 1461e52347bdSJani Nikula Load a policy which meets the needs of the Trusted 1462e52347bdSJani Nikula Computing Base. This means IMA will measure all 1463e52347bdSJani Nikula programs exec'd, files mmap'd for exec, and all files 1464e52347bdSJani Nikula opened for read by uid=0. 1465e52347bdSJani Nikula 1466e52347bdSJani Nikula ima_template= [IMA] 1467e52347bdSJani Nikula Select one of defined IMA measurements template formats. 1468e52347bdSJani Nikula Formats: { "ima" | "ima-ng" | "ima-sig" } 1469e52347bdSJani Nikula Default: "ima-ng" 1470e52347bdSJani Nikula 1471e52347bdSJani Nikula ima_template_fmt= 1472e52347bdSJani Nikula [IMA] Define a custom template format. 1473e52347bdSJani Nikula Format: { "field1|...|fieldN" } 1474e52347bdSJani Nikula 1475e52347bdSJani Nikula ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage 1476e52347bdSJani Nikula Format: <min_file_size> 1477e52347bdSJani Nikula Set the minimal file size for using asynchronous hash. 1478e52347bdSJani Nikula If left unspecified, ahash usage is disabled. 1479e52347bdSJani Nikula 1480e52347bdSJani Nikula ahash performance varies for different data sizes on 1481e52347bdSJani Nikula different crypto accelerators. This option can be used 1482e52347bdSJani Nikula to achieve the best performance for a particular HW. 1483e52347bdSJani Nikula 1484e52347bdSJani Nikula ima.ahash_bufsize= [IMA] Asynchronous hash buffer size 1485e52347bdSJani Nikula Format: <bufsize> 1486e52347bdSJani Nikula Set hashing buffer size. Default: 4k. 1487e52347bdSJani Nikula 1488e52347bdSJani Nikula ahash performance varies for different chunk sizes on 1489e52347bdSJani Nikula different crypto accelerators. This option can be used 1490e52347bdSJani Nikula to achieve best performance for particular HW. 1491e52347bdSJani Nikula 1492e52347bdSJani Nikula init= [KNL] 1493e52347bdSJani Nikula Format: <full_path> 1494e52347bdSJani Nikula Run specified binary instead of /sbin/init as init 1495e52347bdSJani Nikula process. 1496e52347bdSJani Nikula 1497e52347bdSJani Nikula initcall_debug [KNL] Trace initcalls as they are executed. Useful 1498e52347bdSJani Nikula for working out where the kernel is dying during 1499e52347bdSJani Nikula startup. 1500e52347bdSJani Nikula 1501e52347bdSJani Nikula initcall_blacklist= [KNL] Do not execute a comma-separated list of 1502e52347bdSJani Nikula initcall functions. Useful for debugging built-in 1503e52347bdSJani Nikula modules and initcalls. 1504e52347bdSJani Nikula 1505e52347bdSJani Nikula initrd= [BOOT] Specify the location of the initial ramdisk 1506e52347bdSJani Nikula 1507e52347bdSJani Nikula init_pkru= [x86] Specify the default memory protection keys rights 1508e52347bdSJani Nikula register contents for all processes. 0x55555554 by 1509e52347bdSJani Nikula default (disallow access to all but pkey 0). Can 1510e52347bdSJani Nikula override in debugfs after boot. 1511e52347bdSJani Nikula 1512e52347bdSJani Nikula inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver 1513e52347bdSJani Nikula Format: <irq> 1514e52347bdSJani Nikula 1515e52347bdSJani Nikula int_pln_enable [x86] Enable power limit notification interrupt 1516e52347bdSJani Nikula 1517e52347bdSJani Nikula integrity_audit=[IMA] 1518e52347bdSJani Nikula Format: { "0" | "1" } 1519e52347bdSJani Nikula 0 -- basic integrity auditing messages. (Default) 1520e52347bdSJani Nikula 1 -- additional integrity auditing messages. 1521e52347bdSJani Nikula 1522e52347bdSJani Nikula intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option 1523e52347bdSJani Nikula on 1524e52347bdSJani Nikula Enable intel iommu driver. 1525e52347bdSJani Nikula off 1526e52347bdSJani Nikula Disable intel iommu driver. 1527e52347bdSJani Nikula igfx_off [Default Off] 1528e52347bdSJani Nikula By default, gfx is mapped as normal device. If a gfx 1529e52347bdSJani Nikula device has a dedicated DMAR unit, the DMAR unit is 1530e52347bdSJani Nikula bypassed by not enabling DMAR with this option. In 1531e52347bdSJani Nikula this case, gfx device will use physical address for 1532e52347bdSJani Nikula DMA. 1533e52347bdSJani Nikula forcedac [x86_64] 1534e52347bdSJani Nikula With this option iommu will not optimize to look 1535e52347bdSJani Nikula for io virtual address below 32-bit forcing dual 1536e52347bdSJani Nikula address cycle on pci bus for cards supporting greater 1537e52347bdSJani Nikula than 32-bit addressing. The default is to look 1538e52347bdSJani Nikula for translation below 32-bit and if not available 1539e52347bdSJani Nikula then look in the higher range. 1540e52347bdSJani Nikula strict [Default Off] 1541e52347bdSJani Nikula With this option on every unmap_single operation will 1542e52347bdSJani Nikula result in a hardware IOTLB flush operation as opposed 1543e52347bdSJani Nikula to batching them for performance. 1544e52347bdSJani Nikula sp_off [Default Off] 1545e52347bdSJani Nikula By default, super page will be supported if Intel IOMMU 1546e52347bdSJani Nikula has the capability. With this option, super page will 1547e52347bdSJani Nikula not be supported. 1548e52347bdSJani Nikula ecs_off [Default Off] 1549e52347bdSJani Nikula By default, extended context tables will be supported if 1550e52347bdSJani Nikula the hardware advertises that it has support both for the 1551e52347bdSJani Nikula extended tables themselves, and also PASID support. With 1552e52347bdSJani Nikula this option set, extended tables will not be used even 1553e52347bdSJani Nikula on hardware which claims to support them. 1554e52347bdSJani Nikula 1555e52347bdSJani Nikula intel_idle.max_cstate= [KNL,HW,ACPI,X86] 1556e52347bdSJani Nikula 0 disables intel_idle and fall back on acpi_idle. 1557e52347bdSJani Nikula 1 to 9 specify maximum depth of C-state. 1558e52347bdSJani Nikula 1559e52347bdSJani Nikula intel_pstate= [X86] 1560e52347bdSJani Nikula disable 1561e52347bdSJani Nikula Do not enable intel_pstate as the default 1562e52347bdSJani Nikula scaling driver for the supported processors 1563e52347bdSJani Nikula force 1564e52347bdSJani Nikula Enable intel_pstate on systems that prohibit it by default 1565e52347bdSJani Nikula in favor of acpi-cpufreq. Forcing the intel_pstate driver 1566e52347bdSJani Nikula instead of acpi-cpufreq may disable platform features, such 1567e52347bdSJani Nikula as thermal controls and power capping, that rely on ACPI 1568e52347bdSJani Nikula P-States information being indicated to OSPM and therefore 1569e52347bdSJani Nikula should be used with caution. This option does not work with 1570e52347bdSJani Nikula processors that aren't supported by the intel_pstate driver 1571e52347bdSJani Nikula or on platforms that use pcc-cpufreq instead of acpi-cpufreq. 1572e52347bdSJani Nikula no_hwp 1573e52347bdSJani Nikula Do not enable hardware P state control (HWP) 1574e52347bdSJani Nikula if available. 1575e52347bdSJani Nikula hwp_only 1576e52347bdSJani Nikula Only load intel_pstate on systems which support 1577e52347bdSJani Nikula hardware P state control (HWP) if available. 1578e52347bdSJani Nikula support_acpi_ppc 1579e52347bdSJani Nikula Enforce ACPI _PPC performance limits. If the Fixed ACPI 1580e52347bdSJani Nikula Description Table, specifies preferred power management 1581e52347bdSJani Nikula profile as "Enterprise Server" or "Performance Server", 1582e52347bdSJani Nikula then this feature is turned on by default. 1583e52347bdSJani Nikula 1584e52347bdSJani Nikula intremap= [X86-64, Intel-IOMMU] 1585e52347bdSJani Nikula on enable Interrupt Remapping (default) 1586e52347bdSJani Nikula off disable Interrupt Remapping 1587e52347bdSJani Nikula nosid disable Source ID checking 1588e52347bdSJani Nikula no_x2apic_optout 1589e52347bdSJani Nikula BIOS x2APIC opt-out request will be ignored 1590e52347bdSJani Nikula nopost disable Interrupt Posting 1591e52347bdSJani Nikula 1592e52347bdSJani Nikula iomem= Disable strict checking of access to MMIO memory 1593e52347bdSJani Nikula strict regions from userspace. 1594e52347bdSJani Nikula relaxed 1595e52347bdSJani Nikula 1596e52347bdSJani Nikula iommu= [x86] 1597e52347bdSJani Nikula off 1598e52347bdSJani Nikula force 1599e52347bdSJani Nikula noforce 1600e52347bdSJani Nikula biomerge 1601e52347bdSJani Nikula panic 1602e52347bdSJani Nikula nopanic 1603e52347bdSJani Nikula merge 1604e52347bdSJani Nikula nomerge 1605e52347bdSJani Nikula forcesac 1606e52347bdSJani Nikula soft 1607e52347bdSJani Nikula pt [x86, IA-64] 1608e52347bdSJani Nikula nobypass [PPC/POWERNV] 1609e52347bdSJani Nikula Disable IOMMU bypass, using IOMMU for PCI devices. 1610e52347bdSJani Nikula 1611e52347bdSJani Nikula 1612e52347bdSJani Nikula io7= [HW] IO7 for Marvel based alpha systems 1613e52347bdSJani Nikula See comment before marvel_specify_io7 in 1614e52347bdSJani Nikula arch/alpha/kernel/core_marvel.c. 1615e52347bdSJani Nikula 1616e52347bdSJani Nikula io_delay= [X86] I/O delay method 1617e52347bdSJani Nikula 0x80 1618e52347bdSJani Nikula Standard port 0x80 based delay 1619e52347bdSJani Nikula 0xed 1620e52347bdSJani Nikula Alternate port 0xed based delay (needed on some systems) 1621e52347bdSJani Nikula udelay 1622e52347bdSJani Nikula Simple two microseconds delay 1623e52347bdSJani Nikula none 1624e52347bdSJani Nikula No delay 1625e52347bdSJani Nikula 1626e52347bdSJani Nikula ip= [IP_PNP] 1627e52347bdSJani Nikula See Documentation/filesystems/nfs/nfsroot.txt. 1628e52347bdSJani Nikula 1629e52347bdSJani Nikula irqaffinity= [SMP] Set the default irq affinity mask 1630e52347bdSJani Nikula The argument is a cpu list, as described above. 1631e52347bdSJani Nikula 1632e52347bdSJani Nikula irqfixup [HW] 1633e52347bdSJani Nikula When an interrupt is not handled search all handlers 1634e52347bdSJani Nikula for it. Intended to get systems with badly broken 1635e52347bdSJani Nikula firmware running. 1636e52347bdSJani Nikula 1637e52347bdSJani Nikula irqpoll [HW] 1638e52347bdSJani Nikula When an interrupt is not handled search all handlers 1639e52347bdSJani Nikula for it. Also check all handlers each timer 1640e52347bdSJani Nikula interrupt. Intended to get systems with badly broken 1641e52347bdSJani Nikula firmware running. 1642e52347bdSJani Nikula 1643e52347bdSJani Nikula isapnp= [ISAPNP] 1644e52347bdSJani Nikula Format: <RDP>,<reset>,<pci_scan>,<verbosity> 1645e52347bdSJani Nikula 1646e52347bdSJani Nikula isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. 1647e52347bdSJani Nikula The argument is a cpu list, as described above. 1648e52347bdSJani Nikula 1649e52347bdSJani Nikula This option can be used to specify one or more CPUs 1650e52347bdSJani Nikula to isolate from the general SMP balancing and scheduling 1651e52347bdSJani Nikula algorithms. You can move a process onto or off an 1652e52347bdSJani Nikula "isolated" CPU via the CPU affinity syscalls or cpuset. 1653e52347bdSJani Nikula <cpu number> begins at 0 and the maximum value is 1654e52347bdSJani Nikula "number of CPUs in system - 1". 1655e52347bdSJani Nikula 1656e52347bdSJani Nikula This option is the preferred way to isolate CPUs. The 1657e52347bdSJani Nikula alternative -- manually setting the CPU mask of all 1658e52347bdSJani Nikula tasks in the system -- can cause problems and 1659e52347bdSJani Nikula suboptimal load balancer performance. 1660e52347bdSJani Nikula 1661e52347bdSJani Nikula iucv= [HW,NET] 1662e52347bdSJani Nikula 1663e52347bdSJani Nikula ivrs_ioapic [HW,X86_64] 1664e52347bdSJani Nikula Provide an override to the IOAPIC-ID<->DEVICE-ID 1665e52347bdSJani Nikula mapping provided in the IVRS ACPI table. For 1666e52347bdSJani Nikula example, to map IOAPIC-ID decimal 10 to 1667e52347bdSJani Nikula PCI device 00:14.0 write the parameter as: 1668e52347bdSJani Nikula ivrs_ioapic[10]=00:14.0 1669e52347bdSJani Nikula 1670e52347bdSJani Nikula ivrs_hpet [HW,X86_64] 1671e52347bdSJani Nikula Provide an override to the HPET-ID<->DEVICE-ID 1672e52347bdSJani Nikula mapping provided in the IVRS ACPI table. For 1673e52347bdSJani Nikula example, to map HPET-ID decimal 0 to 1674e52347bdSJani Nikula PCI device 00:14.0 write the parameter as: 1675e52347bdSJani Nikula ivrs_hpet[0]=00:14.0 1676e52347bdSJani Nikula 1677e52347bdSJani Nikula ivrs_acpihid [HW,X86_64] 1678e52347bdSJani Nikula Provide an override to the ACPI-HID:UID<->DEVICE-ID 1679e52347bdSJani Nikula mapping provided in the IVRS ACPI table. For 1680e52347bdSJani Nikula example, to map UART-HID:UID AMD0020:0 to 1681e52347bdSJani Nikula PCI device 00:14.5 write the parameter as: 1682e52347bdSJani Nikula ivrs_acpihid[00:14.5]=AMD0020:0 1683e52347bdSJani Nikula 1684e52347bdSJani Nikula js= [HW,JOY] Analog joystick 1685e52347bdSJani Nikula See Documentation/input/joystick.txt. 1686e52347bdSJani Nikula 1687e52347bdSJani Nikula nokaslr [KNL] 1688e52347bdSJani Nikula When CONFIG_RANDOMIZE_BASE is set, this disables 1689e52347bdSJani Nikula kernel and module base offset ASLR (Address Space 1690e52347bdSJani Nikula Layout Randomization). 1691e52347bdSJani Nikula 1692e52347bdSJani Nikula keepinitrd [HW,ARM] 1693e52347bdSJani Nikula 1694e52347bdSJani Nikula kernelcore= [KNL,X86,IA-64,PPC] 1695e52347bdSJani Nikula Format: nn[KMGTPE] | "mirror" 1696e52347bdSJani Nikula This parameter 1697e52347bdSJani Nikula specifies the amount of memory usable by the kernel 1698e52347bdSJani Nikula for non-movable allocations. The requested amount is 1699e52347bdSJani Nikula spread evenly throughout all nodes in the system. The 1700e52347bdSJani Nikula remaining memory in each node is used for Movable 1701e52347bdSJani Nikula pages. In the event, a node is too small to have both 1702e52347bdSJani Nikula kernelcore and Movable pages, kernelcore pages will 1703e52347bdSJani Nikula take priority and other nodes will have a larger number 1704e52347bdSJani Nikula of Movable pages. The Movable zone is used for the 1705e52347bdSJani Nikula allocation of pages that may be reclaimed or moved 1706e52347bdSJani Nikula by the page migration subsystem. This means that 1707e52347bdSJani Nikula HugeTLB pages may not be allocated from this zone. 1708e52347bdSJani Nikula Note that allocations like PTEs-from-HighMem still 1709e52347bdSJani Nikula use the HighMem zone if it exists, and the Normal 1710e52347bdSJani Nikula zone if it does not. 1711e52347bdSJani Nikula 1712e52347bdSJani Nikula Instead of specifying the amount of memory (nn[KMGTPE]), 1713e52347bdSJani Nikula you can specify "mirror" option. In case "mirror" 1714e52347bdSJani Nikula option is specified, mirrored (reliable) memory is used 1715e52347bdSJani Nikula for non-movable allocations and remaining memory is used 1716e52347bdSJani Nikula for Movable pages. nn[KMGTPE] and "mirror" are exclusive, 1717e52347bdSJani Nikula so you can NOT specify nn[KMGTPE] and "mirror" at the same 1718e52347bdSJani Nikula time. 1719e52347bdSJani Nikula 1720e52347bdSJani Nikula kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. 1721e52347bdSJani Nikula Format: <Controller#>[,poll interval] 1722e52347bdSJani Nikula The controller # is the number of the ehci usb debug 1723e52347bdSJani Nikula port as it is probed via PCI. The poll interval is 1724e52347bdSJani Nikula optional and is the number seconds in between 1725e52347bdSJani Nikula each poll cycle to the debug port in case you need 1726e52347bdSJani Nikula the functionality for interrupting the kernel with 1727e52347bdSJani Nikula gdb or control-c on the dbgp connection. When 1728e52347bdSJani Nikula not using this parameter you use sysrq-g to break into 1729e52347bdSJani Nikula the kernel debugger. 1730e52347bdSJani Nikula 1731e52347bdSJani Nikula kgdboc= [KGDB,HW] kgdb over consoles. 1732e52347bdSJani Nikula Requires a tty driver that supports console polling, 1733e52347bdSJani Nikula or a supported polling keyboard driver (non-usb). 1734e52347bdSJani Nikula Serial only format: <serial_device>[,baud] 1735e52347bdSJani Nikula keyboard only format: kbd 1736e52347bdSJani Nikula keyboard and serial format: kbd,<serial_device>[,baud] 1737e52347bdSJani Nikula Optional Kernel mode setting: 1738e52347bdSJani Nikula kms, kbd format: kms,kbd 1739e52347bdSJani Nikula kms, kbd and serial format: kms,kbd,<ser_dev>[,baud] 1740e52347bdSJani Nikula 1741e52347bdSJani Nikula kgdbwait [KGDB] Stop kernel execution and enter the 1742e52347bdSJani Nikula kernel debugger at the earliest opportunity. 1743e52347bdSJani Nikula 1744e52347bdSJani Nikula kmac= [MIPS] korina ethernet MAC address. 1745e52347bdSJani Nikula Configure the RouterBoard 532 series on-chip 1746e52347bdSJani Nikula Ethernet adapter MAC address. 1747e52347bdSJani Nikula 1748e52347bdSJani Nikula kmemleak= [KNL] Boot-time kmemleak enable/disable 1749e52347bdSJani Nikula Valid arguments: on, off 1750e52347bdSJani Nikula Default: on 1751e52347bdSJani Nikula Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, 1752e52347bdSJani Nikula the default is off. 1753e52347bdSJani Nikula 1754e52347bdSJani Nikula kmemcheck= [X86] Boot-time kmemcheck enable/disable/one-shot mode 1755e52347bdSJani Nikula Valid arguments: 0, 1, 2 1756e52347bdSJani Nikula kmemcheck=0 (disabled) 1757e52347bdSJani Nikula kmemcheck=1 (enabled) 1758e52347bdSJani Nikula kmemcheck=2 (one-shot mode) 1759e52347bdSJani Nikula Default: 2 (one-shot mode) 1760e52347bdSJani Nikula 1761e52347bdSJani Nikula kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. 1762e52347bdSJani Nikula Default is 0 (don't ignore, but inject #GP) 1763e52347bdSJani Nikula 1764e52347bdSJani Nikula kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit 1765e52347bdSJani Nikula KVM MMU at runtime. 1766e52347bdSJani Nikula Default is 0 (off) 1767e52347bdSJani Nikula 1768e52347bdSJani Nikula kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM. 1769e52347bdSJani Nikula Default is 1 (enabled) 1770e52347bdSJani Nikula 1771e52347bdSJani Nikula kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU) 1772e52347bdSJani Nikula for all guests. 1773e52347bdSJani Nikula Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. 1774e52347bdSJani Nikula 1775e52347bdSJani Nikula kvm-intel.ept= [KVM,Intel] Disable extended page tables 1776e52347bdSJani Nikula (virtualized MMU) support on capable Intel chips. 1777e52347bdSJani Nikula Default is 1 (enabled) 1778e52347bdSJani Nikula 1779e52347bdSJani Nikula kvm-intel.emulate_invalid_guest_state= 1780e52347bdSJani Nikula [KVM,Intel] Enable emulation of invalid guest states 1781e52347bdSJani Nikula Default is 0 (disabled) 1782e52347bdSJani Nikula 1783e52347bdSJani Nikula kvm-intel.flexpriority= 1784e52347bdSJani Nikula [KVM,Intel] Disable FlexPriority feature (TPR shadow). 1785e52347bdSJani Nikula Default is 1 (enabled) 1786e52347bdSJani Nikula 1787e52347bdSJani Nikula kvm-intel.nested= 1788e52347bdSJani Nikula [KVM,Intel] Enable VMX nesting (nVMX). 1789e52347bdSJani Nikula Default is 0 (disabled) 1790e52347bdSJani Nikula 1791e52347bdSJani Nikula kvm-intel.unrestricted_guest= 1792e52347bdSJani Nikula [KVM,Intel] Disable unrestricted guest feature 1793e52347bdSJani Nikula (virtualized real and unpaged mode) on capable 1794e52347bdSJani Nikula Intel chips. Default is 1 (enabled) 1795e52347bdSJani Nikula 1796e52347bdSJani Nikula kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification 1797e52347bdSJani Nikula feature (tagged TLBs) on capable Intel chips. 1798e52347bdSJani Nikula Default is 1 (enabled) 1799e52347bdSJani Nikula 1800e52347bdSJani Nikula l2cr= [PPC] 1801e52347bdSJani Nikula 1802e52347bdSJani Nikula l3cr= [PPC] 1803e52347bdSJani Nikula 1804e52347bdSJani Nikula lapic [X86-32,APIC] Enable the local APIC even if BIOS 1805e52347bdSJani Nikula disabled it. 1806e52347bdSJani Nikula 1807e52347bdSJani Nikula lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline 1808e52347bdSJani Nikula value for LAPIC timer one-shot implementation. Default 1809e52347bdSJani Nikula back to the programmable timer unit in the LAPIC. 1810e52347bdSJani Nikula 1811e52347bdSJani Nikula lapic_timer_c2_ok [X86,APIC] trust the local apic timer 1812e52347bdSJani Nikula in C2 power state. 1813e52347bdSJani Nikula 1814e52347bdSJani Nikula libata.dma= [LIBATA] DMA control 1815e52347bdSJani Nikula libata.dma=0 Disable all PATA and SATA DMA 1816e52347bdSJani Nikula libata.dma=1 PATA and SATA Disk DMA only 1817e52347bdSJani Nikula libata.dma=2 ATAPI (CDROM) DMA only 1818e52347bdSJani Nikula libata.dma=4 Compact Flash DMA only 1819e52347bdSJani Nikula Combinations also work, so libata.dma=3 enables DMA 1820e52347bdSJani Nikula for disks and CDROMs, but not CFs. 1821e52347bdSJani Nikula 1822e52347bdSJani Nikula libata.ignore_hpa= [LIBATA] Ignore HPA limit 1823e52347bdSJani Nikula libata.ignore_hpa=0 keep BIOS limits (default) 1824e52347bdSJani Nikula libata.ignore_hpa=1 ignore limits, using full disk 1825e52347bdSJani Nikula 1826e52347bdSJani Nikula libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume 1827e52347bdSJani Nikula when set. 1828e52347bdSJani Nikula Format: <int> 1829e52347bdSJani Nikula 1830e52347bdSJani Nikula libata.force= [LIBATA] Force configurations. The format is comma 1831e52347bdSJani Nikula separated list of "[ID:]VAL" where ID is 1832e52347bdSJani Nikula PORT[.DEVICE]. PORT and DEVICE are decimal numbers 1833e52347bdSJani Nikula matching port, link or device. Basically, it matches 1834e52347bdSJani Nikula the ATA ID string printed on console by libata. If 1835e52347bdSJani Nikula the whole ID part is omitted, the last PORT and DEVICE 1836e52347bdSJani Nikula values are used. If ID hasn't been specified yet, the 1837e52347bdSJani Nikula configuration applies to all ports, links and devices. 1838e52347bdSJani Nikula 1839e52347bdSJani Nikula If only DEVICE is omitted, the parameter applies to 1840e52347bdSJani Nikula the port and all links and devices behind it. DEVICE 1841e52347bdSJani Nikula number of 0 either selects the first device or the 1842e52347bdSJani Nikula first fan-out link behind PMP device. It does not 1843e52347bdSJani Nikula select the host link. DEVICE number of 15 selects the 1844e52347bdSJani Nikula host link and device attached to it. 1845e52347bdSJani Nikula 1846e52347bdSJani Nikula The VAL specifies the configuration to force. As long 1847e52347bdSJani Nikula as there's no ambiguity shortcut notation is allowed. 1848e52347bdSJani Nikula For example, both 1.5 and 1.5G would work for 1.5Gbps. 1849e52347bdSJani Nikula The following configurations can be forced. 1850e52347bdSJani Nikula 1851e52347bdSJani Nikula * Cable type: 40c, 80c, short40c, unk, ign or sata. 1852e52347bdSJani Nikula Any ID with matching PORT is used. 1853e52347bdSJani Nikula 1854e52347bdSJani Nikula * SATA link speed limit: 1.5Gbps or 3.0Gbps. 1855e52347bdSJani Nikula 1856e52347bdSJani Nikula * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. 1857e52347bdSJani Nikula udma[/][16,25,33,44,66,100,133] notation is also 1858e52347bdSJani Nikula allowed. 1859e52347bdSJani Nikula 1860e52347bdSJani Nikula * [no]ncq: Turn on or off NCQ. 1861e52347bdSJani Nikula 1862e52347bdSJani Nikula * [no]ncqtrim: Turn off queued DSM TRIM. 1863e52347bdSJani Nikula 1864e52347bdSJani Nikula * nohrst, nosrst, norst: suppress hard, soft 1865e52347bdSJani Nikula and both resets. 1866e52347bdSJani Nikula 1867e52347bdSJani Nikula * rstonce: only attempt one reset during 1868e52347bdSJani Nikula hot-unplug link recovery 1869e52347bdSJani Nikula 1870e52347bdSJani Nikula * dump_id: dump IDENTIFY data. 1871e52347bdSJani Nikula 1872e52347bdSJani Nikula * atapi_dmadir: Enable ATAPI DMADIR bridge support 1873e52347bdSJani Nikula 1874e52347bdSJani Nikula * disable: Disable this device. 1875e52347bdSJani Nikula 1876e52347bdSJani Nikula If there are multiple matching configurations changing 1877e52347bdSJani Nikula the same attribute, the last one is used. 1878e52347bdSJani Nikula 1879e52347bdSJani Nikula memblock=debug [KNL] Enable memblock debug messages. 1880e52347bdSJani Nikula 1881e52347bdSJani Nikula load_ramdisk= [RAM] List of ramdisks to load from floppy 1882e52347bdSJani Nikula See Documentation/blockdev/ramdisk.txt. 1883e52347bdSJani Nikula 1884e52347bdSJani Nikula lockd.nlm_grace_period=P [NFS] Assign grace period. 1885e52347bdSJani Nikula Format: <integer> 1886e52347bdSJani Nikula 1887e52347bdSJani Nikula lockd.nlm_tcpport=N [NFS] Assign TCP port. 1888e52347bdSJani Nikula Format: <integer> 1889e52347bdSJani Nikula 1890e52347bdSJani Nikula lockd.nlm_timeout=T [NFS] Assign timeout value. 1891e52347bdSJani Nikula Format: <integer> 1892e52347bdSJani Nikula 1893e52347bdSJani Nikula lockd.nlm_udpport=M [NFS] Assign UDP port. 1894e52347bdSJani Nikula Format: <integer> 1895e52347bdSJani Nikula 1896e52347bdSJani Nikula locktorture.nreaders_stress= [KNL] 1897e52347bdSJani Nikula Set the number of locking read-acquisition kthreads. 1898e52347bdSJani Nikula Defaults to being automatically set based on the 1899e52347bdSJani Nikula number of online CPUs. 1900e52347bdSJani Nikula 1901e52347bdSJani Nikula locktorture.nwriters_stress= [KNL] 1902e52347bdSJani Nikula Set the number of locking write-acquisition kthreads. 1903e52347bdSJani Nikula 1904e52347bdSJani Nikula locktorture.onoff_holdoff= [KNL] 1905e52347bdSJani Nikula Set time (s) after boot for CPU-hotplug testing. 1906e52347bdSJani Nikula 1907e52347bdSJani Nikula locktorture.onoff_interval= [KNL] 1908e52347bdSJani Nikula Set time (s) between CPU-hotplug operations, or 1909e52347bdSJani Nikula zero to disable CPU-hotplug testing. 1910e52347bdSJani Nikula 1911e52347bdSJani Nikula locktorture.shuffle_interval= [KNL] 1912e52347bdSJani Nikula Set task-shuffle interval (jiffies). Shuffling 1913e52347bdSJani Nikula tasks allows some CPUs to go into dyntick-idle 1914e52347bdSJani Nikula mode during the locktorture test. 1915e52347bdSJani Nikula 1916e52347bdSJani Nikula locktorture.shutdown_secs= [KNL] 1917e52347bdSJani Nikula Set time (s) after boot system shutdown. This 1918e52347bdSJani Nikula is useful for hands-off automated testing. 1919e52347bdSJani Nikula 1920e52347bdSJani Nikula locktorture.stat_interval= [KNL] 1921e52347bdSJani Nikula Time (s) between statistics printk()s. 1922e52347bdSJani Nikula 1923e52347bdSJani Nikula locktorture.stutter= [KNL] 1924e52347bdSJani Nikula Time (s) to stutter testing, for example, 1925e52347bdSJani Nikula specifying five seconds causes the test to run for 1926e52347bdSJani Nikula five seconds, wait for five seconds, and so on. 1927e52347bdSJani Nikula This tests the locking primitive's ability to 1928e52347bdSJani Nikula transition abruptly to and from idle. 1929e52347bdSJani Nikula 1930e52347bdSJani Nikula locktorture.torture_runnable= [BOOT] 1931e52347bdSJani Nikula Start locktorture running at boot time. 1932e52347bdSJani Nikula 1933e52347bdSJani Nikula locktorture.torture_type= [KNL] 1934e52347bdSJani Nikula Specify the locking implementation to test. 1935e52347bdSJani Nikula 1936e52347bdSJani Nikula locktorture.verbose= [KNL] 1937e52347bdSJani Nikula Enable additional printk() statements. 1938e52347bdSJani Nikula 1939e52347bdSJani Nikula logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver 1940e52347bdSJani Nikula Format: <irq> 1941e52347bdSJani Nikula 1942e52347bdSJani Nikula loglevel= All Kernel Messages with a loglevel smaller than the 1943e52347bdSJani Nikula console loglevel will be printed to the console. It can 1944e52347bdSJani Nikula also be changed with klogd or other programs. The 1945e52347bdSJani Nikula loglevels are defined as follows: 1946e52347bdSJani Nikula 1947e52347bdSJani Nikula 0 (KERN_EMERG) system is unusable 1948e52347bdSJani Nikula 1 (KERN_ALERT) action must be taken immediately 1949e52347bdSJani Nikula 2 (KERN_CRIT) critical conditions 1950e52347bdSJani Nikula 3 (KERN_ERR) error conditions 1951e52347bdSJani Nikula 4 (KERN_WARNING) warning conditions 1952e52347bdSJani Nikula 5 (KERN_NOTICE) normal but significant condition 1953e52347bdSJani Nikula 6 (KERN_INFO) informational 1954e52347bdSJani Nikula 7 (KERN_DEBUG) debug-level messages 1955e52347bdSJani Nikula 1956e52347bdSJani Nikula log_buf_len=n[KMG] Sets the size of the printk ring buffer, 1957e52347bdSJani Nikula in bytes. n must be a power of two and greater 1958e52347bdSJani Nikula than the minimal size. The minimal size is defined 1959e52347bdSJani Nikula by LOG_BUF_SHIFT kernel config parameter. There is 1960e52347bdSJani Nikula also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter 1961e52347bdSJani Nikula that allows to increase the default size depending on 1962e52347bdSJani Nikula the number of CPUs. See init/Kconfig for more details. 1963e52347bdSJani Nikula 1964e52347bdSJani Nikula logo.nologo [FB] Disables display of the built-in Linux logo. 1965e52347bdSJani Nikula This may be used to provide more screen space for 1966e52347bdSJani Nikula kernel log messages and is useful when debugging 1967e52347bdSJani Nikula kernel boot problems. 1968e52347bdSJani Nikula 1969e52347bdSJani Nikula lp=0 [LP] Specify parallel ports to use, e.g, 1970e52347bdSJani Nikula lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 1971e52347bdSJani Nikula lp=reset first parallel port). 'lp=0' disables the 1972e52347bdSJani Nikula lp=auto printer driver. 'lp=reset' (which can be 1973e52347bdSJani Nikula specified in addition to the ports) causes 1974e52347bdSJani Nikula attached printers to be reset. Using 1975e52347bdSJani Nikula lp=port1,port2,... specifies the parallel ports 1976e52347bdSJani Nikula to associate lp devices with, starting with 1977e52347bdSJani Nikula lp0. A port specification may be 'none' to skip 1978e52347bdSJani Nikula that lp device, or a parport name such as 1979e52347bdSJani Nikula 'parport0'. Specifying 'lp=auto' instead of a 1980e52347bdSJani Nikula port specification list means that device IDs 1981e52347bdSJani Nikula from each port should be examined, to see if 1982e52347bdSJani Nikula an IEEE 1284-compliant printer is attached; if 1983e52347bdSJani Nikula so, the driver will manage that printer. 1984e52347bdSJani Nikula See also header of drivers/char/lp.c. 1985e52347bdSJani Nikula 1986e52347bdSJani Nikula lpj=n [KNL] 1987e52347bdSJani Nikula Sets loops_per_jiffy to given constant, thus avoiding 1988e52347bdSJani Nikula time-consuming boot-time autodetection (up to 250 ms per 1989e52347bdSJani Nikula CPU). 0 enables autodetection (default). To determine 1990e52347bdSJani Nikula the correct value for your kernel, boot with normal 1991e52347bdSJani Nikula autodetection and see what value is printed. Note that 1992e52347bdSJani Nikula on SMP systems the preset will be applied to all CPUs, 1993e52347bdSJani Nikula which is likely to cause problems if your CPUs need 1994e52347bdSJani Nikula significantly divergent settings. An incorrect value 1995e52347bdSJani Nikula will cause delays in the kernel to be wrong, leading to 1996e52347bdSJani Nikula unpredictable I/O errors and other breakage. Although 1997e52347bdSJani Nikula unlikely, in the extreme case this might damage your 1998e52347bdSJani Nikula hardware. 1999e52347bdSJani Nikula 2000e52347bdSJani Nikula ltpc= [NET] 2001e52347bdSJani Nikula Format: <io>,<irq>,<dma> 2002e52347bdSJani Nikula 2003e52347bdSJani Nikula machvec= [IA-64] Force the use of a particular machine-vector 2004e52347bdSJani Nikula (machvec) in a generic kernel. 2005e52347bdSJani Nikula Example: machvec=hpzx1_swiotlb 2006e52347bdSJani Nikula 2007e52347bdSJani Nikula machtype= [Loongson] Share the same kernel image file between different 2008e52347bdSJani Nikula yeeloong laptop. 2009e52347bdSJani Nikula Example: machtype=lemote-yeeloong-2f-7inch 2010e52347bdSJani Nikula 2011e52347bdSJani Nikula max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater 2012e52347bdSJani Nikula than or equal to this physical address is ignored. 2013e52347bdSJani Nikula 2014e52347bdSJani Nikula maxcpus= [SMP] Maximum number of processors that an SMP kernel 2015e52347bdSJani Nikula will bring up during bootup. maxcpus=n : n >= 0 limits 2016e52347bdSJani Nikula the kernel to bring up 'n' processors. Surely after 2017e52347bdSJani Nikula bootup you can bring up the other plugged cpu by executing 2018e52347bdSJani Nikula "echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus 2019e52347bdSJani Nikula only takes effect during system bootup. 2020e52347bdSJani Nikula While n=0 is a special case, it is equivalent to "nosmp", 2021e52347bdSJani Nikula which also disables the IO APIC. 2022e52347bdSJani Nikula 2023e52347bdSJani Nikula max_loop= [LOOP] The number of loop block devices that get 2024e52347bdSJani Nikula (loop.max_loop) unconditionally pre-created at init time. The default 2025e52347bdSJani Nikula number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead 2026e52347bdSJani Nikula of statically allocating a predefined number, loop 2027e52347bdSJani Nikula devices can be requested on-demand with the 2028e52347bdSJani Nikula /dev/loop-control interface. 2029e52347bdSJani Nikula 2030e52347bdSJani Nikula mce [X86-32] Machine Check Exception 2031e52347bdSJani Nikula 2032e52347bdSJani Nikula mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt 2033e52347bdSJani Nikula 2034e52347bdSJani Nikula md= [HW] RAID subsystems devices and level 2035e52347bdSJani Nikula See Documentation/admin-guide/md.rst. 2036e52347bdSJani Nikula 2037e52347bdSJani Nikula mdacon= [MDA] 2038e52347bdSJani Nikula Format: <first>,<last> 2039e52347bdSJani Nikula Specifies range of consoles to be captured by the MDA. 2040e52347bdSJani Nikula 2041e52347bdSJani Nikula mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory 2042e52347bdSJani Nikula Amount of memory to be used when the kernel is not able 2043e52347bdSJani Nikula to see the whole system memory or for test. 2044e52347bdSJani Nikula [X86] Work as limiting max address. Use together 2045e52347bdSJani Nikula with memmap= to avoid physical address space collisions. 2046e52347bdSJani Nikula Without memmap= PCI devices could be placed at addresses 2047e52347bdSJani Nikula belonging to unused RAM. 2048e52347bdSJani Nikula 2049e52347bdSJani Nikula mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel 2050e52347bdSJani Nikula memory. 2051e52347bdSJani Nikula 2052e52347bdSJani Nikula memchunk=nn[KMG] 2053e52347bdSJani Nikula [KNL,SH] Allow user to override the default size for 2054e52347bdSJani Nikula per-device physically contiguous DMA buffers. 2055e52347bdSJani Nikula 2056e52347bdSJani Nikula memhp_default_state=online/offline 2057e52347bdSJani Nikula [KNL] Set the initial state for the memory hotplug 2058e52347bdSJani Nikula onlining policy. If not specified, the default value is 2059e52347bdSJani Nikula set according to the 2060e52347bdSJani Nikula CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config 2061e52347bdSJani Nikula option. 2062e52347bdSJani Nikula See Documentation/memory-hotplug.txt. 2063e52347bdSJani Nikula 2064e52347bdSJani Nikula memmap=exactmap [KNL,X86] Enable setting of an exact 2065e52347bdSJani Nikula E820 memory map, as specified by the user. 2066e52347bdSJani Nikula Such memmap=exactmap lines can be constructed based on 2067e52347bdSJani Nikula BIOS output or other requirements. See the memmap=nn@ss 2068e52347bdSJani Nikula option description. 2069e52347bdSJani Nikula 2070e52347bdSJani Nikula memmap=nn[KMG]@ss[KMG] 2071e52347bdSJani Nikula [KNL] Force usage of a specific region of memory. 2072e52347bdSJani Nikula Region of memory to be used is from ss to ss+nn. 2073e52347bdSJani Nikula 2074e52347bdSJani Nikula memmap=nn[KMG]#ss[KMG] 2075e52347bdSJani Nikula [KNL,ACPI] Mark specific memory as ACPI data. 2076e52347bdSJani Nikula Region of memory to be marked is from ss to ss+nn. 2077e52347bdSJani Nikula 2078e52347bdSJani Nikula memmap=nn[KMG]$ss[KMG] 2079e52347bdSJani Nikula [KNL,ACPI] Mark specific memory as reserved. 2080e52347bdSJani Nikula Region of memory to be reserved is from ss to ss+nn. 2081e52347bdSJani Nikula Example: Exclude memory from 0x18690000-0x1869ffff 2082e52347bdSJani Nikula memmap=64K$0x18690000 2083e52347bdSJani Nikula or 2084e52347bdSJani Nikula memmap=0x10000$0x18690000 2085e52347bdSJani Nikula 2086e52347bdSJani Nikula memmap=nn[KMG]!ss[KMG] 2087e52347bdSJani Nikula [KNL,X86] Mark specific memory as protected. 2088e52347bdSJani Nikula Region of memory to be used, from ss to ss+nn. 2089e52347bdSJani Nikula The memory region may be marked as e820 type 12 (0xc) 2090e52347bdSJani Nikula and is NVDIMM or ADR memory. 2091e52347bdSJani Nikula 2092e52347bdSJani Nikula memory_corruption_check=0/1 [X86] 2093e52347bdSJani Nikula Some BIOSes seem to corrupt the first 64k of 2094e52347bdSJani Nikula memory when doing things like suspend/resume. 2095e52347bdSJani Nikula Setting this option will scan the memory 2096e52347bdSJani Nikula looking for corruption. Enabling this will 2097e52347bdSJani Nikula both detect corruption and prevent the kernel 2098e52347bdSJani Nikula from using the memory being corrupted. 2099e52347bdSJani Nikula However, its intended as a diagnostic tool; if 2100e52347bdSJani Nikula repeatable BIOS-originated corruption always 2101e52347bdSJani Nikula affects the same memory, you can use memmap= 2102e52347bdSJani Nikula to prevent the kernel from using that memory. 2103e52347bdSJani Nikula 2104e52347bdSJani Nikula memory_corruption_check_size=size [X86] 2105e52347bdSJani Nikula By default it checks for corruption in the low 2106e52347bdSJani Nikula 64k, making this memory unavailable for normal 2107e52347bdSJani Nikula use. Use this parameter to scan for 2108e52347bdSJani Nikula corruption in more or less memory. 2109e52347bdSJani Nikula 2110e52347bdSJani Nikula memory_corruption_check_period=seconds [X86] 2111e52347bdSJani Nikula By default it checks for corruption every 60 2112e52347bdSJani Nikula seconds. Use this parameter to check at some 2113e52347bdSJani Nikula other rate. 0 disables periodic checking. 2114e52347bdSJani Nikula 2115e52347bdSJani Nikula memtest= [KNL,X86,ARM] Enable memtest 2116e52347bdSJani Nikula Format: <integer> 2117e52347bdSJani Nikula default : 0 <disable> 2118e52347bdSJani Nikula Specifies the number of memtest passes to be 2119e52347bdSJani Nikula performed. Each pass selects another test 2120e52347bdSJani Nikula pattern from a given set of patterns. Memtest 2121e52347bdSJani Nikula fills the memory with this pattern, validates 2122e52347bdSJani Nikula memory contents and reserves bad memory 2123e52347bdSJani Nikula regions that are detected. 2124e52347bdSJani Nikula 2125e52347bdSJani Nikula meye.*= [HW] Set MotionEye Camera parameters 2126e52347bdSJani Nikula See Documentation/video4linux/meye.txt. 2127e52347bdSJani Nikula 2128e52347bdSJani Nikula mfgpt_irq= [IA-32] Specify the IRQ to use for the 2129e52347bdSJani Nikula Multi-Function General Purpose Timers on AMD Geode 2130e52347bdSJani Nikula platforms. 2131e52347bdSJani Nikula 2132e52347bdSJani Nikula mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when 2133e52347bdSJani Nikula the BIOS has incorrectly applied a workaround. TinyBIOS 2134e52347bdSJani Nikula version 0.98 is known to be affected, 0.99 fixes the 2135e52347bdSJani Nikula problem by letting the user disable the workaround. 2136e52347bdSJani Nikula 2137e52347bdSJani Nikula mga= [HW,DRM] 2138e52347bdSJani Nikula 2139e52347bdSJani Nikula min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this 2140e52347bdSJani Nikula physical address is ignored. 2141e52347bdSJani Nikula 2142e52347bdSJani Nikula mini2440= [ARM,HW,KNL] 2143e52347bdSJani Nikula Format:[0..2][b][c][t] 2144e52347bdSJani Nikula Default: "0tb" 2145e52347bdSJani Nikula MINI2440 configuration specification: 2146e52347bdSJani Nikula 0 - The attached screen is the 3.5" TFT 2147e52347bdSJani Nikula 1 - The attached screen is the 7" TFT 2148e52347bdSJani Nikula 2 - The VGA Shield is attached (1024x768) 2149e52347bdSJani Nikula Leaving out the screen size parameter will not load 2150e52347bdSJani Nikula the TFT driver, and the framebuffer will be left 2151e52347bdSJani Nikula unconfigured. 2152e52347bdSJani Nikula b - Enable backlight. The TFT backlight pin will be 2153e52347bdSJani Nikula linked to the kernel VESA blanking code and a GPIO 2154e52347bdSJani Nikula LED. This parameter is not necessary when using the 2155e52347bdSJani Nikula VGA shield. 2156e52347bdSJani Nikula c - Enable the s3c camera interface. 2157e52347bdSJani Nikula t - Reserved for enabling touchscreen support. The 2158e52347bdSJani Nikula touchscreen support is not enabled in the mainstream 2159e52347bdSJani Nikula kernel as of 2.6.30, a preliminary port can be found 2160e52347bdSJani Nikula in the "bleeding edge" mini2440 support kernel at 2161e52347bdSJani Nikula http://repo.or.cz/w/linux-2.6/mini2440.git 2162e52347bdSJani Nikula 2163e52347bdSJani Nikula mminit_loglevel= 2164e52347bdSJani Nikula [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this 2165e52347bdSJani Nikula parameter allows control of the logging verbosity for 2166e52347bdSJani Nikula the additional memory initialisation checks. A value 2167e52347bdSJani Nikula of 0 disables mminit logging and a level of 4 will 2168e52347bdSJani Nikula log everything. Information is printed at KERN_DEBUG 2169e52347bdSJani Nikula so loglevel=8 may also need to be specified. 2170e52347bdSJani Nikula 2171e52347bdSJani Nikula module.sig_enforce 2172e52347bdSJani Nikula [KNL] When CONFIG_MODULE_SIG is set, this means that 2173e52347bdSJani Nikula modules without (valid) signatures will fail to load. 2174e52347bdSJani Nikula Note that if CONFIG_MODULE_SIG_FORCE is set, that 2175e52347bdSJani Nikula is always true, so this option does nothing. 2176e52347bdSJani Nikula 2177e52347bdSJani Nikula module_blacklist= [KNL] Do not load a comma-separated list of 2178e52347bdSJani Nikula modules. Useful for debugging problem modules. 2179e52347bdSJani Nikula 2180e52347bdSJani Nikula mousedev.tap_time= 2181e52347bdSJani Nikula [MOUSE] Maximum time between finger touching and 2182e52347bdSJani Nikula leaving touchpad surface for touch to be considered 2183e52347bdSJani Nikula a tap and be reported as a left button click (for 2184e52347bdSJani Nikula touchpads working in absolute mode only). 2185e52347bdSJani Nikula Format: <msecs> 2186e52347bdSJani Nikula mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices 2187e52347bdSJani Nikula reporting absolute coordinates, such as tablets 2188e52347bdSJani Nikula mousedev.yres= [MOUSE] Vertical screen resolution, used for devices 2189e52347bdSJani Nikula reporting absolute coordinates, such as tablets 2190e52347bdSJani Nikula 2191e52347bdSJani Nikula movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter 2192e52347bdSJani Nikula is similar to kernelcore except it specifies the 2193e52347bdSJani Nikula amount of memory used for migratable allocations. 2194e52347bdSJani Nikula If both kernelcore and movablecore is specified, 2195e52347bdSJani Nikula then kernelcore will be at *least* the specified 2196e52347bdSJani Nikula value but may be more. If movablecore on its own 2197e52347bdSJani Nikula is specified, the administrator must be careful 2198e52347bdSJani Nikula that the amount of memory usable for all allocations 2199e52347bdSJani Nikula is not too small. 2200e52347bdSJani Nikula 2201e7aa8c2eSLinus Torvalds movable_node [KNL] Boot-time switch to enable the effects 2202e52347bdSJani Nikula of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details. 2203e52347bdSJani Nikula 2204e52347bdSJani Nikula MTD_Partition= [MTD] 2205e52347bdSJani Nikula Format: <name>,<region-number>,<size>,<offset> 2206e52347bdSJani Nikula 2207e52347bdSJani Nikula MTD_Region= [MTD] Format: 2208e52347bdSJani Nikula <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] 2209e52347bdSJani Nikula 2210e52347bdSJani Nikula mtdparts= [MTD] 2211e52347bdSJani Nikula See drivers/mtd/cmdlinepart.c. 2212e52347bdSJani Nikula 2213e52347bdSJani Nikula multitce=off [PPC] This parameter disables the use of the pSeries 2214e52347bdSJani Nikula firmware feature for updating multiple TCE entries 2215e52347bdSJani Nikula at a time. 2216e52347bdSJani Nikula 2217e52347bdSJani Nikula onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration 2218e52347bdSJani Nikula 2219e52347bdSJani Nikula Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] 2220e52347bdSJani Nikula 2221e52347bdSJani Nikula boundary - index of last SLC block on Flex-OneNAND. 2222e52347bdSJani Nikula The remaining blocks are configured as MLC blocks. 2223e52347bdSJani Nikula lock - Configure if Flex-OneNAND boundary should be locked. 2224e52347bdSJani Nikula Once locked, the boundary cannot be changed. 2225e52347bdSJani Nikula 1 indicates lock status, 0 indicates unlock status. 2226e52347bdSJani Nikula 2227e52347bdSJani Nikula mtdset= [ARM] 2228e52347bdSJani Nikula ARM/S3C2412 JIVE boot control 2229e52347bdSJani Nikula 2230e52347bdSJani Nikula See arch/arm/mach-s3c2412/mach-jive.c 2231e52347bdSJani Nikula 2232e52347bdSJani Nikula mtouchusb.raw_coordinates= 2233e52347bdSJani Nikula [HW] Make the MicroTouch USB driver use raw coordinates 2234e52347bdSJani Nikula ('y', default) or cooked coordinates ('n') 2235e52347bdSJani Nikula 2236e52347bdSJani Nikula mtrr_chunk_size=nn[KMG] [X86] 2237e52347bdSJani Nikula used for mtrr cleanup. It is largest continuous chunk 2238e52347bdSJani Nikula that could hold holes aka. UC entries. 2239e52347bdSJani Nikula 2240e52347bdSJani Nikula mtrr_gran_size=nn[KMG] [X86] 2241e52347bdSJani Nikula Used for mtrr cleanup. It is granularity of mtrr block. 2242e52347bdSJani Nikula Default is 1. 2243e52347bdSJani Nikula Large value could prevent small alignment from 2244e52347bdSJani Nikula using up MTRRs. 2245e52347bdSJani Nikula 2246e52347bdSJani Nikula mtrr_spare_reg_nr=n [X86] 2247e52347bdSJani Nikula Format: <integer> 2248e52347bdSJani Nikula Range: 0,7 : spare reg number 2249e52347bdSJani Nikula Default : 1 2250e52347bdSJani Nikula Used for mtrr cleanup. It is spare mtrr entries number. 2251e52347bdSJani Nikula Set to 2 or more if your graphical card needs more. 2252e52347bdSJani Nikula 2253e52347bdSJani Nikula n2= [NET] SDL Inc. RISCom/N2 synchronous serial card 2254e52347bdSJani Nikula 2255e52347bdSJani Nikula netdev= [NET] Network devices parameters 2256e52347bdSJani Nikula Format: <irq>,<io>,<mem_start>,<mem_end>,<name> 2257e52347bdSJani Nikula Note that mem_start is often overloaded to mean 2258e52347bdSJani Nikula something different and driver-specific. 2259e52347bdSJani Nikula This usage is only documented in each driver source 2260e52347bdSJani Nikula file if at all. 2261e52347bdSJani Nikula 2262e52347bdSJani Nikula nf_conntrack.acct= 2263e52347bdSJani Nikula [NETFILTER] Enable connection tracking flow accounting 2264e52347bdSJani Nikula 0 to disable accounting 2265e52347bdSJani Nikula 1 to enable accounting 2266e52347bdSJani Nikula Default value is 0. 2267e52347bdSJani Nikula 2268e52347bdSJani Nikula nfsaddrs= [NFS] Deprecated. Use ip= instead. 2269e52347bdSJani Nikula See Documentation/filesystems/nfs/nfsroot.txt. 2270e52347bdSJani Nikula 2271e52347bdSJani Nikula nfsroot= [NFS] nfs root filesystem for disk-less boxes. 2272e52347bdSJani Nikula See Documentation/filesystems/nfs/nfsroot.txt. 2273e52347bdSJani Nikula 2274e52347bdSJani Nikula nfsrootdebug [NFS] enable nfsroot debugging messages. 2275e52347bdSJani Nikula See Documentation/filesystems/nfs/nfsroot.txt. 2276e52347bdSJani Nikula 2277e52347bdSJani Nikula nfs.callback_nr_threads= 2278e52347bdSJani Nikula [NFSv4] set the total number of threads that the 2279e52347bdSJani Nikula NFS client will assign to service NFSv4 callback 2280e52347bdSJani Nikula requests. 2281e52347bdSJani Nikula 2282e52347bdSJani Nikula nfs.callback_tcpport= 2283e52347bdSJani Nikula [NFS] set the TCP port on which the NFSv4 callback 2284e52347bdSJani Nikula channel should listen. 2285e52347bdSJani Nikula 2286e52347bdSJani Nikula nfs.cache_getent= 2287e52347bdSJani Nikula [NFS] sets the pathname to the program which is used 2288e52347bdSJani Nikula to update the NFS client cache entries. 2289e52347bdSJani Nikula 2290e52347bdSJani Nikula nfs.cache_getent_timeout= 2291e52347bdSJani Nikula [NFS] sets the timeout after which an attempt to 2292e52347bdSJani Nikula update a cache entry is deemed to have failed. 2293e52347bdSJani Nikula 2294e52347bdSJani Nikula nfs.idmap_cache_timeout= 2295e52347bdSJani Nikula [NFS] set the maximum lifetime for idmapper cache 2296e52347bdSJani Nikula entries. 2297e52347bdSJani Nikula 2298e52347bdSJani Nikula nfs.enable_ino64= 2299e52347bdSJani Nikula [NFS] enable 64-bit inode numbers. 2300e52347bdSJani Nikula If zero, the NFS client will fake up a 32-bit inode 2301e52347bdSJani Nikula number for the readdir() and stat() syscalls instead 2302e52347bdSJani Nikula of returning the full 64-bit number. 2303e52347bdSJani Nikula The default is to return 64-bit inode numbers. 2304e52347bdSJani Nikula 2305e52347bdSJani Nikula nfs.max_session_cb_slots= 2306e52347bdSJani Nikula [NFSv4.1] Sets the maximum number of session 2307e52347bdSJani Nikula slots the client will assign to the callback 2308e52347bdSJani Nikula channel. This determines the maximum number of 2309e52347bdSJani Nikula callbacks the client will process in parallel for 2310e52347bdSJani Nikula a particular server. 2311e52347bdSJani Nikula 2312e52347bdSJani Nikula nfs.max_session_slots= 2313e52347bdSJani Nikula [NFSv4.1] Sets the maximum number of session slots 2314e52347bdSJani Nikula the client will attempt to negotiate with the server. 2315e52347bdSJani Nikula This limits the number of simultaneous RPC requests 2316e52347bdSJani Nikula that the client can send to the NFSv4.1 server. 2317e52347bdSJani Nikula Note that there is little point in setting this 2318e52347bdSJani Nikula value higher than the max_tcp_slot_table_limit. 2319e52347bdSJani Nikula 2320e52347bdSJani Nikula nfs.nfs4_disable_idmapping= 2321e52347bdSJani Nikula [NFSv4] When set to the default of '1', this option 2322e52347bdSJani Nikula ensures that both the RPC level authentication 2323e52347bdSJani Nikula scheme and the NFS level operations agree to use 2324e52347bdSJani Nikula numeric uids/gids if the mount is using the 2325e52347bdSJani Nikula 'sec=sys' security flavour. In effect it is 2326e52347bdSJani Nikula disabling idmapping, which can make migration from 2327e52347bdSJani Nikula legacy NFSv2/v3 systems to NFSv4 easier. 2328e52347bdSJani Nikula Servers that do not support this mode of operation 2329e52347bdSJani Nikula will be autodetected by the client, and it will fall 2330e52347bdSJani Nikula back to using the idmapper. 2331e52347bdSJani Nikula To turn off this behaviour, set the value to '0'. 2332e52347bdSJani Nikula nfs.nfs4_unique_id= 2333e52347bdSJani Nikula [NFS4] Specify an additional fixed unique ident- 2334e52347bdSJani Nikula ification string that NFSv4 clients can insert into 2335e52347bdSJani Nikula their nfs_client_id4 string. This is typically a 2336e52347bdSJani Nikula UUID that is generated at system install time. 2337e52347bdSJani Nikula 2338e52347bdSJani Nikula nfs.send_implementation_id = 2339e52347bdSJani Nikula [NFSv4.1] Send client implementation identification 2340e52347bdSJani Nikula information in exchange_id requests. 2341e52347bdSJani Nikula If zero, no implementation identification information 2342e52347bdSJani Nikula will be sent. 2343e52347bdSJani Nikula The default is to send the implementation identification 2344e52347bdSJani Nikula information. 2345e52347bdSJani Nikula 2346e52347bdSJani Nikula nfs.recover_lost_locks = 2347e52347bdSJani Nikula [NFSv4] Attempt to recover locks that were lost due 2348e52347bdSJani Nikula to a lease timeout on the server. Please note that 2349e52347bdSJani Nikula doing this risks data corruption, since there are 2350e52347bdSJani Nikula no guarantees that the file will remain unchanged 2351e52347bdSJani Nikula after the locks are lost. 2352e52347bdSJani Nikula If you want to enable the kernel legacy behaviour of 2353e52347bdSJani Nikula attempting to recover these locks, then set this 2354e52347bdSJani Nikula parameter to '1'. 2355e52347bdSJani Nikula The default parameter value of '0' causes the kernel 2356e52347bdSJani Nikula not to attempt recovery of lost locks. 2357e52347bdSJani Nikula 2358e52347bdSJani Nikula nfs4.layoutstats_timer = 2359e52347bdSJani Nikula [NFSv4.2] Change the rate at which the kernel sends 2360e52347bdSJani Nikula layoutstats to the pNFS metadata server. 2361e52347bdSJani Nikula 2362e52347bdSJani Nikula Setting this to value to 0 causes the kernel to use 2363e52347bdSJani Nikula whatever value is the default set by the layout 2364e52347bdSJani Nikula driver. A non-zero value sets the minimum interval 2365e52347bdSJani Nikula in seconds between layoutstats transmissions. 2366e52347bdSJani Nikula 2367e52347bdSJani Nikula nfsd.nfs4_disable_idmapping= 2368e52347bdSJani Nikula [NFSv4] When set to the default of '1', the NFSv4 2369e52347bdSJani Nikula server will return only numeric uids and gids to 2370e52347bdSJani Nikula clients using auth_sys, and will accept numeric uids 2371e52347bdSJani Nikula and gids from such clients. This is intended to ease 2372e52347bdSJani Nikula migration from NFSv2/v3. 2373e52347bdSJani Nikula 2374e52347bdSJani Nikula objlayoutdriver.osd_login_prog= 2375e52347bdSJani Nikula [NFS] [OBJLAYOUT] sets the pathname to the program which 2376e52347bdSJani Nikula is used to automatically discover and login into new 2377e52347bdSJani Nikula osd-targets. Please see: 2378e52347bdSJani Nikula Documentation/filesystems/pnfs.txt for more explanations 2379e52347bdSJani Nikula 2380e52347bdSJani Nikula nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take 2381e52347bdSJani Nikula when a NMI is triggered. 2382e52347bdSJani Nikula Format: [state][,regs][,debounce][,die] 2383e52347bdSJani Nikula 2384e52347bdSJani Nikula nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels 2385e52347bdSJani Nikula Format: [panic,][nopanic,][num] 2386e52347bdSJani Nikula Valid num: 0 or 1 2387e52347bdSJani Nikula 0 - turn hardlockup detector in nmi_watchdog off 2388e52347bdSJani Nikula 1 - turn hardlockup detector in nmi_watchdog on 2389e52347bdSJani Nikula When panic is specified, panic when an NMI watchdog 2390e52347bdSJani Nikula timeout occurs (or 'nopanic' to override the opposite 2391e52347bdSJani Nikula default). To disable both hard and soft lockup detectors, 2392e52347bdSJani Nikula please see 'nowatchdog'. 2393e52347bdSJani Nikula This is useful when you use a panic=... timeout and 2394e52347bdSJani Nikula need the box quickly up again. 2395e52347bdSJani Nikula 2396e52347bdSJani Nikula netpoll.carrier_timeout= 2397e52347bdSJani Nikula [NET] Specifies amount of time (in seconds) that 2398e52347bdSJani Nikula netpoll should wait for a carrier. By default netpoll 2399e52347bdSJani Nikula waits 4 seconds. 2400e52347bdSJani Nikula 2401e52347bdSJani Nikula no387 [BUGS=X86-32] Tells the kernel to use the 387 maths 2402e52347bdSJani Nikula emulation library even if a 387 maths coprocessor 2403e52347bdSJani Nikula is present. 2404e52347bdSJani Nikula 2405e52347bdSJani Nikula no_console_suspend 2406e52347bdSJani Nikula [HW] Never suspend the console 2407e52347bdSJani Nikula Disable suspending of consoles during suspend and 2408e52347bdSJani Nikula hibernate operations. Once disabled, debugging 2409e52347bdSJani Nikula messages can reach various consoles while the rest 2410e52347bdSJani Nikula of the system is being put to sleep (ie, while 2411e52347bdSJani Nikula debugging driver suspend/resume hooks). This may 2412e52347bdSJani Nikula not work reliably with all consoles, but is known 2413e52347bdSJani Nikula to work with serial and VGA consoles. 2414e52347bdSJani Nikula To facilitate more flexible debugging, we also add 2415e52347bdSJani Nikula console_suspend, a printk module parameter to control 2416e52347bdSJani Nikula it. Users could use console_suspend (usually 2417e52347bdSJani Nikula /sys/module/printk/parameters/console_suspend) to 2418e52347bdSJani Nikula turn on/off it dynamically. 2419e52347bdSJani Nikula 2420e52347bdSJani Nikula noaliencache [MM, NUMA, SLAB] Disables the allocation of alien 2421e52347bdSJani Nikula caches in the slab allocator. Saves per-node memory, 2422e52347bdSJani Nikula but will impact performance. 2423e52347bdSJani Nikula 2424e52347bdSJani Nikula noalign [KNL,ARM] 2425e52347bdSJani Nikula 2426e52347bdSJani Nikula noapic [SMP,APIC] Tells the kernel to not make use of any 2427e52347bdSJani Nikula IOAPICs that may be present in the system. 2428e52347bdSJani Nikula 2429e52347bdSJani Nikula noautogroup Disable scheduler automatic task group creation. 2430e52347bdSJani Nikula 2431e52347bdSJani Nikula nobats [PPC] Do not use BATs for mapping kernel lowmem 2432e52347bdSJani Nikula on "Classic" PPC cores. 2433e52347bdSJani Nikula 2434e52347bdSJani Nikula nocache [ARM] 2435e52347bdSJani Nikula 2436e52347bdSJani Nikula noclflush [BUGS=X86] Don't use the CLFLUSH instruction 2437e52347bdSJani Nikula 2438e52347bdSJani Nikula nodelayacct [KNL] Disable per-task delay accounting 2439e52347bdSJani Nikula 2440e52347bdSJani Nikula nodsp [SH] Disable hardware DSP at boot time. 2441e52347bdSJani Nikula 2442e52347bdSJani Nikula noefi Disable EFI runtime services support. 2443e52347bdSJani Nikula 2444e52347bdSJani Nikula noexec [IA-64] 2445e52347bdSJani Nikula 2446e52347bdSJani Nikula noexec [X86] 2447e52347bdSJani Nikula On X86-32 available only on PAE configured kernels. 2448e52347bdSJani Nikula noexec=on: enable non-executable mappings (default) 2449e52347bdSJani Nikula noexec=off: disable non-executable mappings 2450e52347bdSJani Nikula 2451e52347bdSJani Nikula nosmap [X86] 2452e52347bdSJani Nikula Disable SMAP (Supervisor Mode Access Prevention) 2453e52347bdSJani Nikula even if it is supported by processor. 2454e52347bdSJani Nikula 2455e52347bdSJani Nikula nosmep [X86] 2456e52347bdSJani Nikula Disable SMEP (Supervisor Mode Execution Prevention) 2457e52347bdSJani Nikula even if it is supported by processor. 2458e52347bdSJani Nikula 2459e52347bdSJani Nikula noexec32 [X86-64] 2460e52347bdSJani Nikula This affects only 32-bit executables. 2461e52347bdSJani Nikula noexec32=on: enable non-executable mappings (default) 2462e52347bdSJani Nikula read doesn't imply executable mappings 2463e52347bdSJani Nikula noexec32=off: disable non-executable mappings 2464e52347bdSJani Nikula read implies executable mappings 2465e52347bdSJani Nikula 2466e52347bdSJani Nikula nofpu [MIPS,SH] Disable hardware FPU at boot time. 2467e52347bdSJani Nikula 2468e52347bdSJani Nikula nofxsr [BUGS=X86-32] Disables x86 floating point extended 2469e52347bdSJani Nikula register save and restore. The kernel will only save 2470e52347bdSJani Nikula legacy floating-point registers on task switch. 2471e52347bdSJani Nikula 2472e52347bdSJani Nikula nohugeiomap [KNL,x86] Disable kernel huge I/O mappings. 2473e52347bdSJani Nikula 2474e52347bdSJani Nikula nosmt [KNL,S390] Disable symmetric multithreading (SMT). 2475e52347bdSJani Nikula Equivalent to smt=1. 2476e52347bdSJani Nikula 2477e52347bdSJani Nikula noxsave [BUGS=X86] Disables x86 extended register state save 2478e52347bdSJani Nikula and restore using xsave. The kernel will fallback to 2479e52347bdSJani Nikula enabling legacy floating-point and sse state. 2480e52347bdSJani Nikula 2481e52347bdSJani Nikula noxsaveopt [X86] Disables xsaveopt used in saving x86 extended 2482e52347bdSJani Nikula register states. The kernel will fall back to use 2483e52347bdSJani Nikula xsave to save the states. By using this parameter, 2484e52347bdSJani Nikula performance of saving the states is degraded because 2485e52347bdSJani Nikula xsave doesn't support modified optimization while 2486e52347bdSJani Nikula xsaveopt supports it on xsaveopt enabled systems. 2487e52347bdSJani Nikula 2488e52347bdSJani Nikula noxsaves [X86] Disables xsaves and xrstors used in saving and 2489e52347bdSJani Nikula restoring x86 extended register state in compacted 2490e52347bdSJani Nikula form of xsave area. The kernel will fall back to use 2491e52347bdSJani Nikula xsaveopt and xrstor to save and restore the states 2492e52347bdSJani Nikula in standard form of xsave area. By using this 2493e52347bdSJani Nikula parameter, xsave area per process might occupy more 2494e52347bdSJani Nikula memory on xsaves enabled systems. 2495e52347bdSJani Nikula 2496e52347bdSJani Nikula nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or 2497e52347bdSJani Nikula wfi(ARM) instruction doesn't work correctly and not to 2498e52347bdSJani Nikula use it. This is also useful when using JTAG debugger. 2499e52347bdSJani Nikula 2500e52347bdSJani Nikula no_file_caps Tells the kernel not to honor file capabilities. The 2501e52347bdSJani Nikula only way then for a file to be executed with privilege 2502e52347bdSJani Nikula is to be setuid root or executed by root. 2503e52347bdSJani Nikula 2504e52347bdSJani Nikula nohalt [IA-64] Tells the kernel not to use the power saving 2505e52347bdSJani Nikula function PAL_HALT_LIGHT when idle. This increases 2506e52347bdSJani Nikula power-consumption. On the positive side, it reduces 2507e52347bdSJani Nikula interrupt wake-up latency, which may improve performance 2508e52347bdSJani Nikula in certain environments such as networked servers or 2509e52347bdSJani Nikula real-time systems. 2510e52347bdSJani Nikula 2511e52347bdSJani Nikula nohibernate [HIBERNATION] Disable hibernation and resume. 2512e52347bdSJani Nikula 2513e52347bdSJani Nikula nohz= [KNL] Boottime enable/disable dynamic ticks 2514e52347bdSJani Nikula Valid arguments: on, off 2515e52347bdSJani Nikula Default: on 2516e52347bdSJani Nikula 2517e52347bdSJani Nikula nohz_full= [KNL,BOOT] 2518e52347bdSJani Nikula The argument is a cpu list, as described above. 2519e52347bdSJani Nikula In kernels built with CONFIG_NO_HZ_FULL=y, set 2520e52347bdSJani Nikula the specified list of CPUs whose tick will be stopped 2521e52347bdSJani Nikula whenever possible. The boot CPU will be forced outside 2522e52347bdSJani Nikula the range to maintain the timekeeping. 2523e52347bdSJani Nikula The CPUs in this range must also be included in the 2524e52347bdSJani Nikula rcu_nocbs= set. 2525e52347bdSJani Nikula 2526e52347bdSJani Nikula noiotrap [SH] Disables trapped I/O port accesses. 2527e52347bdSJani Nikula 2528e52347bdSJani Nikula noirqdebug [X86-32] Disables the code which attempts to detect and 2529e52347bdSJani Nikula disable unhandled interrupt sources. 2530e52347bdSJani Nikula 2531e52347bdSJani Nikula no_timer_check [X86,APIC] Disables the code which tests for 2532e52347bdSJani Nikula broken timer IRQ sources. 2533e52347bdSJani Nikula 2534e52347bdSJani Nikula noisapnp [ISAPNP] Disables ISA PnP code. 2535e52347bdSJani Nikula 2536e52347bdSJani Nikula noinitrd [RAM] Tells the kernel not to load any configured 2537e52347bdSJani Nikula initial RAM disk. 2538e52347bdSJani Nikula 2539e52347bdSJani Nikula nointremap [X86-64, Intel-IOMMU] Do not enable interrupt 2540e52347bdSJani Nikula remapping. 2541e52347bdSJani Nikula [Deprecated - use intremap=off] 2542e52347bdSJani Nikula 2543e52347bdSJani Nikula nointroute [IA-64] 2544e52347bdSJani Nikula 2545e52347bdSJani Nikula noinvpcid [X86] Disable the INVPCID cpu feature. 2546e52347bdSJani Nikula 2547e52347bdSJani Nikula nojitter [IA-64] Disables jitter checking for ITC timers. 2548e52347bdSJani Nikula 2549e52347bdSJani Nikula no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver 2550e52347bdSJani Nikula 2551e52347bdSJani Nikula no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page 2552e52347bdSJani Nikula fault handling. 2553e52347bdSJani Nikula 2554e7aa8c2eSLinus Torvalds no-vmw-sched-clock 2555e7aa8c2eSLinus Torvalds [X86,PV_OPS] Disable paravirtualized VMware scheduler 2556e7aa8c2eSLinus Torvalds clock and use the default one. 2557e7aa8c2eSLinus Torvalds 2558e52347bdSJani Nikula no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting. 2559e52347bdSJani Nikula steal time is computed, but won't influence scheduler 2560e52347bdSJani Nikula behaviour 2561e52347bdSJani Nikula 2562e52347bdSJani Nikula nolapic [X86-32,APIC] Do not enable or use the local APIC. 2563e52347bdSJani Nikula 2564e52347bdSJani Nikula nolapic_timer [X86-32,APIC] Do not use the local APIC timer. 2565e52347bdSJani Nikula 2566e52347bdSJani Nikula noltlbs [PPC] Do not use large page/tlb entries for kernel 2567e52347bdSJani Nikula lowmem mapping on PPC40x and PPC8xx 2568e52347bdSJani Nikula 2569e52347bdSJani Nikula nomca [IA-64] Disable machine check abort handling 2570e52347bdSJani Nikula 2571e52347bdSJani Nikula nomce [X86-32] Disable Machine Check Exception 2572e52347bdSJani Nikula 2573e52347bdSJani Nikula nomfgpt [X86-32] Disable Multi-Function General Purpose 2574e52347bdSJani Nikula Timer usage (for AMD Geode machines). 2575e52347bdSJani Nikula 2576e52347bdSJani Nikula nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to 2577e52347bdSJani Nikula shutdown the other cpus. Instead use the REBOOT_VECTOR 2578e52347bdSJani Nikula irq. 2579e52347bdSJani Nikula 2580e52347bdSJani Nikula nomodule Disable module load 2581e52347bdSJani Nikula 2582e52347bdSJani Nikula nopat [X86] Disable PAT (page attribute table extension of 2583e52347bdSJani Nikula pagetables) support. 2584e52347bdSJani Nikula 2585e52347bdSJani Nikula norandmaps Don't use address space randomization. Equivalent to 2586e52347bdSJani Nikula echo 0 > /proc/sys/kernel/randomize_va_space 2587e52347bdSJani Nikula 2588e52347bdSJani Nikula noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops 2589e52347bdSJani Nikula 2590e52347bdSJani Nikula noreplace-smp [X86-32,SMP] Don't replace SMP instructions 2591e52347bdSJani Nikula with UP alternatives 2592e52347bdSJani Nikula 2593e52347bdSJani Nikula nordrand [X86] Disable kernel use of the RDRAND and 2594e52347bdSJani Nikula RDSEED instructions even if they are supported 2595e52347bdSJani Nikula by the processor. RDRAND and RDSEED are still 2596e52347bdSJani Nikula available to user space applications. 2597e52347bdSJani Nikula 2598e52347bdSJani Nikula noresume [SWSUSP] Disables resume and restores original swap 2599e52347bdSJani Nikula space. 2600e52347bdSJani Nikula 2601e52347bdSJani Nikula no-scroll [VGA] Disables scrollback. 2602e52347bdSJani Nikula This is required for the Braillex ib80-piezo Braille 2603e52347bdSJani Nikula reader made by F.H. Papenmeier (Germany). 2604e52347bdSJani Nikula 2605e52347bdSJani Nikula nosbagart [IA-64] 2606e52347bdSJani Nikula 2607e52347bdSJani Nikula nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. 2608e52347bdSJani Nikula 2609e52347bdSJani Nikula nosmp [SMP] Tells an SMP kernel to act as a UP kernel, 2610e52347bdSJani Nikula and disable the IO APIC. legacy for "maxcpus=0". 2611e52347bdSJani Nikula 2612e52347bdSJani Nikula nosoftlockup [KNL] Disable the soft-lockup detector. 2613e52347bdSJani Nikula 2614e52347bdSJani Nikula nosync [HW,M68K] Disables sync negotiation for all devices. 2615e52347bdSJani Nikula 2616e52347bdSJani Nikula notsc [BUGS=X86-32] Disable Time Stamp Counter 2617e52347bdSJani Nikula 2618e52347bdSJani Nikula nowatchdog [KNL] Disable both lockup detectors, i.e. 2619e52347bdSJani Nikula soft-lockup and NMI watchdog (hard-lockup). 2620e52347bdSJani Nikula 2621e52347bdSJani Nikula nowb [ARM] 2622e52347bdSJani Nikula 2623e52347bdSJani Nikula nox2apic [X86-64,APIC] Do not enable x2APIC mode. 2624e52347bdSJani Nikula 2625e52347bdSJani Nikula cpu0_hotplug [X86] Turn on CPU0 hotplug feature when 2626e52347bdSJani Nikula CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. 2627e52347bdSJani Nikula Some features depend on CPU0. Known dependencies are: 2628e52347bdSJani Nikula 1. Resume from suspend/hibernate depends on CPU0. 2629e52347bdSJani Nikula Suspend/hibernate will fail if CPU0 is offline and you 2630e52347bdSJani Nikula need to online CPU0 before suspend/hibernate. 2631e52347bdSJani Nikula 2. PIC interrupts also depend on CPU0. CPU0 can't be 2632e52347bdSJani Nikula removed if a PIC interrupt is detected. 2633e52347bdSJani Nikula It's said poweroff/reboot may depend on CPU0 on some 2634e52347bdSJani Nikula machines although I haven't seen such issues so far 2635e52347bdSJani Nikula after CPU0 is offline on a few tested machines. 2636e52347bdSJani Nikula If the dependencies are under your control, you can 2637e52347bdSJani Nikula turn on cpu0_hotplug. 2638e52347bdSJani Nikula 2639e52347bdSJani Nikula nptcg= [IA-64] Override max number of concurrent global TLB 2640e52347bdSJani Nikula purges which is reported from either PAL_VM_SUMMARY or 2641e52347bdSJani Nikula SAL PALO. 2642e52347bdSJani Nikula 2643e52347bdSJani Nikula nr_cpus= [SMP] Maximum number of processors that an SMP kernel 2644e52347bdSJani Nikula could support. nr_cpus=n : n >= 1 limits the kernel to 2645e52347bdSJani Nikula support 'n' processors. It could be larger than the 2646e52347bdSJani Nikula number of already plugged CPU during bootup, later in 2647e52347bdSJani Nikula runtime you can physically add extra cpu until it reaches 2648e52347bdSJani Nikula n. So during boot up some boot time memory for per-cpu 2649e52347bdSJani Nikula variables need be pre-allocated for later physical cpu 2650e52347bdSJani Nikula hot plugging. 2651e52347bdSJani Nikula 2652e52347bdSJani Nikula nr_uarts= [SERIAL] maximum number of UARTs to be registered. 2653e52347bdSJani Nikula 2654e52347bdSJani Nikula numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing. 2655e52347bdSJani Nikula Allowed values are enable and disable 2656e52347bdSJani Nikula 2657e52347bdSJani Nikula numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. 2658e52347bdSJani Nikula one of ['zone', 'node', 'default'] can be specified 2659e52347bdSJani Nikula This can be set from sysctl after boot. 2660e52347bdSJani Nikula See Documentation/sysctl/vm.txt for details. 2661e52347bdSJani Nikula 2662e52347bdSJani Nikula ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. 2663e52347bdSJani Nikula See Documentation/debugging-via-ohci1394.txt for more 2664e52347bdSJani Nikula info. 2665e52347bdSJani Nikula 2666e52347bdSJani Nikula olpc_ec_timeout= [OLPC] ms delay when issuing EC commands 2667e52347bdSJani Nikula Rather than timing out after 20 ms if an EC 2668e52347bdSJani Nikula command is not properly ACKed, override the length 2669e52347bdSJani Nikula of the timeout. We have interrupts disabled while 2670e52347bdSJani Nikula waiting for the ACK, so if this is set too high 2671e52347bdSJani Nikula interrupts *may* be lost! 2672e52347bdSJani Nikula 2673e52347bdSJani Nikula omap_mux= [OMAP] Override bootloader pin multiplexing. 2674e52347bdSJani Nikula Format: <mux_mode0.mode_name=value>... 2675e52347bdSJani Nikula For example, to override I2C bus2: 2676e52347bdSJani Nikula omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 2677e52347bdSJani Nikula 2678e52347bdSJani Nikula oprofile.timer= [HW] 2679e52347bdSJani Nikula Use timer interrupt instead of performance counters 2680e52347bdSJani Nikula 2681e52347bdSJani Nikula oprofile.cpu_type= Force an oprofile cpu type 2682e52347bdSJani Nikula This might be useful if you have an older oprofile 2683e52347bdSJani Nikula userland or if you want common events. 2684e52347bdSJani Nikula Format: { arch_perfmon } 2685e52347bdSJani Nikula arch_perfmon: [X86] Force use of architectural 2686e52347bdSJani Nikula perfmon on Intel CPUs instead of the 2687e52347bdSJani Nikula CPU specific event set. 2688e52347bdSJani Nikula timer: [X86] Force use of architectural NMI 2689e52347bdSJani Nikula timer mode (see also oprofile.timer 2690e52347bdSJani Nikula for generic hr timer mode) 2691e52347bdSJani Nikula 2692e52347bdSJani Nikula oops=panic Always panic on oopses. Default is to just kill the 2693e52347bdSJani Nikula process, but there is a small probability of 2694e52347bdSJani Nikula deadlocking the machine. 2695e52347bdSJani Nikula This will also cause panics on machine check exceptions. 2696e52347bdSJani Nikula Useful together with panic=30 to trigger a reboot. 2697e52347bdSJani Nikula 2698e52347bdSJani Nikula OSS [HW,OSS] 2699e52347bdSJani Nikula See Documentation/sound/oss/oss-parameters.txt 2700e52347bdSJani Nikula 2701e52347bdSJani Nikula page_owner= [KNL] Boot-time page_owner enabling option. 2702e52347bdSJani Nikula Storage of the information about who allocated 2703e52347bdSJani Nikula each page is disabled in default. With this switch, 2704e52347bdSJani Nikula we can turn it on. 2705e52347bdSJani Nikula on: enable the feature 2706e52347bdSJani Nikula 2707e52347bdSJani Nikula page_poison= [KNL] Boot-time parameter changing the state of 2708e52347bdSJani Nikula poisoning on the buddy allocator. 2709e52347bdSJani Nikula off: turn off poisoning 2710e52347bdSJani Nikula on: turn on poisoning 2711e52347bdSJani Nikula 2712e52347bdSJani Nikula panic= [KNL] Kernel behaviour on panic: delay <timeout> 2713e52347bdSJani Nikula timeout > 0: seconds before rebooting 2714e52347bdSJani Nikula timeout = 0: wait forever 2715e52347bdSJani Nikula timeout < 0: reboot immediately 2716e52347bdSJani Nikula Format: <timeout> 2717e52347bdSJani Nikula 2718e52347bdSJani Nikula panic_on_warn panic() instead of WARN(). Useful to cause kdump 2719e52347bdSJani Nikula on a WARN(). 2720e52347bdSJani Nikula 2721e52347bdSJani Nikula crash_kexec_post_notifiers 2722e52347bdSJani Nikula Run kdump after running panic-notifiers and dumping 2723e52347bdSJani Nikula kmsg. This only for the users who doubt kdump always 2724e52347bdSJani Nikula succeeds in any situation. 2725e52347bdSJani Nikula Note that this also increases risks of kdump failure, 2726e52347bdSJani Nikula because some panic notifiers can make the crashed 2727e52347bdSJani Nikula kernel more unstable. 2728e52347bdSJani Nikula 2729e52347bdSJani Nikula parkbd.port= [HW] Parallel port number the keyboard adapter is 2730e52347bdSJani Nikula connected to, default is 0. 2731e52347bdSJani Nikula Format: <parport#> 2732e52347bdSJani Nikula parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, 2733e52347bdSJani Nikula 0 for XT, 1 for AT (default is AT). 2734e52347bdSJani Nikula Format: <mode> 2735e52347bdSJani Nikula 2736e52347bdSJani Nikula parport= [HW,PPT] Specify parallel ports. 0 disables. 2737e52347bdSJani Nikula Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } 2738e52347bdSJani Nikula Use 'auto' to force the driver to use any 2739e52347bdSJani Nikula IRQ/DMA settings detected (the default is to 2740e52347bdSJani Nikula ignore detected IRQ/DMA settings because of 2741e52347bdSJani Nikula possible conflicts). You can specify the base 2742e52347bdSJani Nikula address, IRQ, and DMA settings; IRQ and DMA 2743e52347bdSJani Nikula should be numbers, or 'auto' (for using detected 2744e52347bdSJani Nikula settings on that particular port), or 'nofifo' 2745e52347bdSJani Nikula (to avoid using a FIFO even if it is detected). 2746e52347bdSJani Nikula Parallel ports are assigned in the order they 2747e52347bdSJani Nikula are specified on the command line, starting 2748e52347bdSJani Nikula with parport0. 2749e52347bdSJani Nikula 2750e52347bdSJani Nikula parport_init_mode= [HW,PPT] 2751e52347bdSJani Nikula Configure VIA parallel port to operate in 2752e52347bdSJani Nikula a specific mode. This is necessary on Pegasos 2753e52347bdSJani Nikula computer where firmware has no options for setting 2754e52347bdSJani Nikula up parallel port mode and sets it to spp. 2755e52347bdSJani Nikula Currently this function knows 686a and 8231 chips. 2756e52347bdSJani Nikula Format: [spp|ps2|epp|ecp|ecpepp] 2757e52347bdSJani Nikula 2758e52347bdSJani Nikula pause_on_oops= 2759e52347bdSJani Nikula Halt all CPUs after the first oops has been printed for 2760e52347bdSJani Nikula the specified number of seconds. This is to be used if 2761e52347bdSJani Nikula your oopses keep scrolling off the screen. 2762e52347bdSJani Nikula 2763e52347bdSJani Nikula pcbit= [HW,ISDN] 2764e52347bdSJani Nikula 2765e52347bdSJani Nikula pcd. [PARIDE] 2766e52347bdSJani Nikula See header of drivers/block/paride/pcd.c. 2767e52347bdSJani Nikula See also Documentation/blockdev/paride.txt. 2768e52347bdSJani Nikula 2769e52347bdSJani Nikula pci=option[,option...] [PCI] various PCI subsystem options: 2770e52347bdSJani Nikula earlydump [X86] dump PCI config space before the kernel 2771e52347bdSJani Nikula changes anything 2772e52347bdSJani Nikula off [X86] don't probe for the PCI bus 2773e52347bdSJani Nikula bios [X86-32] force use of PCI BIOS, don't access 2774e52347bdSJani Nikula the hardware directly. Use this if your machine 2775e52347bdSJani Nikula has a non-standard PCI host bridge. 2776e52347bdSJani Nikula nobios [X86-32] disallow use of PCI BIOS, only direct 2777e52347bdSJani Nikula hardware access methods are allowed. Use this 2778e52347bdSJani Nikula if you experience crashes upon bootup and you 2779e52347bdSJani Nikula suspect they are caused by the BIOS. 2780e52347bdSJani Nikula conf1 [X86] Force use of PCI Configuration Access 2781e52347bdSJani Nikula Mechanism 1 (config address in IO port 0xCF8, 2782e52347bdSJani Nikula data in IO port 0xCFC, both 32-bit). 2783e52347bdSJani Nikula conf2 [X86] Force use of PCI Configuration Access 2784e52347bdSJani Nikula Mechanism 2 (IO port 0xCF8 is an 8-bit port for 2785e52347bdSJani Nikula the function, IO port 0xCFA, also 8-bit, sets 2786e52347bdSJani Nikula bus number. The config space is then accessed 2787e52347bdSJani Nikula through ports 0xC000-0xCFFF). 2788e52347bdSJani Nikula See http://wiki.osdev.org/PCI for more info 2789e52347bdSJani Nikula on the configuration access mechanisms. 2790e52347bdSJani Nikula noaer [PCIE] If the PCIEAER kernel config parameter is 2791e52347bdSJani Nikula enabled, this kernel boot option can be used to 2792e52347bdSJani Nikula disable the use of PCIE advanced error reporting. 2793e52347bdSJani Nikula nodomains [PCI] Disable support for multiple PCI 2794e52347bdSJani Nikula root domains (aka PCI segments, in ACPI-speak). 2795e52347bdSJani Nikula nommconf [X86] Disable use of MMCONFIG for PCI 2796e52347bdSJani Nikula Configuration 2797e52347bdSJani Nikula check_enable_amd_mmconf [X86] check for and enable 2798e52347bdSJani Nikula properly configured MMIO access to PCI 2799e52347bdSJani Nikula config space on AMD family 10h CPU 2800e52347bdSJani Nikula nomsi [MSI] If the PCI_MSI kernel config parameter is 2801e52347bdSJani Nikula enabled, this kernel boot option can be used to 2802e52347bdSJani Nikula disable the use of MSI interrupts system-wide. 2803e52347bdSJani Nikula noioapicquirk [APIC] Disable all boot interrupt quirks. 2804e52347bdSJani Nikula Safety option to keep boot IRQs enabled. This 2805e52347bdSJani Nikula should never be necessary. 2806e52347bdSJani Nikula ioapicreroute [APIC] Enable rerouting of boot IRQs to the 2807e52347bdSJani Nikula primary IO-APIC for bridges that cannot disable 2808e52347bdSJani Nikula boot IRQs. This fixes a source of spurious IRQs 2809e52347bdSJani Nikula when the system masks IRQs. 2810e52347bdSJani Nikula noioapicreroute [APIC] Disable workaround that uses the 2811e52347bdSJani Nikula boot IRQ equivalent of an IRQ that connects to 2812e52347bdSJani Nikula a chipset where boot IRQs cannot be disabled. 2813e52347bdSJani Nikula The opposite of ioapicreroute. 2814e52347bdSJani Nikula biosirq [X86-32] Use PCI BIOS calls to get the interrupt 2815e52347bdSJani Nikula routing table. These calls are known to be buggy 2816e52347bdSJani Nikula on several machines and they hang the machine 2817e52347bdSJani Nikula when used, but on other computers it's the only 2818e52347bdSJani Nikula way to get the interrupt routing table. Try 2819e52347bdSJani Nikula this option if the kernel is unable to allocate 2820e52347bdSJani Nikula IRQs or discover secondary PCI buses on your 2821e52347bdSJani Nikula motherboard. 2822e52347bdSJani Nikula rom [X86] Assign address space to expansion ROMs. 2823e52347bdSJani Nikula Use with caution as certain devices share 2824e52347bdSJani Nikula address decoders between ROMs and other 2825e52347bdSJani Nikula resources. 2826e52347bdSJani Nikula norom [X86] Do not assign address space to 2827e52347bdSJani Nikula expansion ROMs that do not already have 2828e52347bdSJani Nikula BIOS assigned address ranges. 2829e52347bdSJani Nikula nobar [X86] Do not assign address space to the 2830e52347bdSJani Nikula BARs that weren't assigned by the BIOS. 2831e52347bdSJani Nikula irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be 2832e52347bdSJani Nikula assigned automatically to PCI devices. You can 2833e52347bdSJani Nikula make the kernel exclude IRQs of your ISA cards 2834e52347bdSJani Nikula this way. 2835e52347bdSJani Nikula pirqaddr=0xAAAAA [X86] Specify the physical address 2836e52347bdSJani Nikula of the PIRQ table (normally generated 2837e52347bdSJani Nikula by the BIOS) if it is outside the 2838e52347bdSJani Nikula F0000h-100000h range. 2839e52347bdSJani Nikula lastbus=N [X86] Scan all buses thru bus #N. Can be 2840e52347bdSJani Nikula useful if the kernel is unable to find your 2841e52347bdSJani Nikula secondary buses and you want to tell it 2842e52347bdSJani Nikula explicitly which ones they are. 2843e52347bdSJani Nikula assign-busses [X86] Always assign all PCI bus 2844e52347bdSJani Nikula numbers ourselves, overriding 2845e52347bdSJani Nikula whatever the firmware may have done. 2846e52347bdSJani Nikula usepirqmask [X86] Honor the possible IRQ mask stored 2847e52347bdSJani Nikula in the BIOS $PIR table. This is needed on 2848e52347bdSJani Nikula some systems with broken BIOSes, notably 2849e52347bdSJani Nikula some HP Pavilion N5400 and Omnibook XE3 2850e52347bdSJani Nikula notebooks. This will have no effect if ACPI 2851e52347bdSJani Nikula IRQ routing is enabled. 2852e52347bdSJani Nikula noacpi [X86] Do not use ACPI for IRQ routing 2853e52347bdSJani Nikula or for PCI scanning. 2854e52347bdSJani Nikula use_crs [X86] Use PCI host bridge window information 2855e52347bdSJani Nikula from ACPI. On BIOSes from 2008 or later, this 2856e52347bdSJani Nikula is enabled by default. If you need to use this, 2857e52347bdSJani Nikula please report a bug. 2858e52347bdSJani Nikula nocrs [X86] Ignore PCI host bridge windows from ACPI. 2859e52347bdSJani Nikula If you need to use this, please report a bug. 2860e52347bdSJani Nikula routeirq Do IRQ routing for all PCI devices. 2861e52347bdSJani Nikula This is normally done in pci_enable_device(), 2862e52347bdSJani Nikula so this option is a temporary workaround 2863e52347bdSJani Nikula for broken drivers that don't call it. 2864e52347bdSJani Nikula skip_isa_align [X86] do not align io start addr, so can 2865e52347bdSJani Nikula handle more pci cards 2866e52347bdSJani Nikula noearly [X86] Don't do any early type 1 scanning. 2867e52347bdSJani Nikula This might help on some broken boards which 2868e52347bdSJani Nikula machine check when some devices' config space 2869e52347bdSJani Nikula is read. But various workarounds are disabled 2870e52347bdSJani Nikula and some IOMMU drivers will not work. 2871e52347bdSJani Nikula bfsort Sort PCI devices into breadth-first order. 2872e52347bdSJani Nikula This sorting is done to get a device 2873e52347bdSJani Nikula order compatible with older (<= 2.4) kernels. 2874e52347bdSJani Nikula nobfsort Don't sort PCI devices into breadth-first order. 2875e52347bdSJani Nikula pcie_bus_tune_off Disable PCIe MPS (Max Payload Size) 2876e52347bdSJani Nikula tuning and use the BIOS-configured MPS defaults. 2877e52347bdSJani Nikula pcie_bus_safe Set every device's MPS to the largest value 2878e52347bdSJani Nikula supported by all devices below the root complex. 2879e52347bdSJani Nikula pcie_bus_perf Set device MPS to the largest allowable MPS 2880e52347bdSJani Nikula based on its parent bus. Also set MRRS (Max 2881e52347bdSJani Nikula Read Request Size) to the largest supported 2882e52347bdSJani Nikula value (no larger than the MPS that the device 2883e52347bdSJani Nikula or bus can support) for best performance. 2884e52347bdSJani Nikula pcie_bus_peer2peer Set every device's MPS to 128B, which 2885e52347bdSJani Nikula every device is guaranteed to support. This 2886e52347bdSJani Nikula configuration allows peer-to-peer DMA between 2887e52347bdSJani Nikula any pair of devices, possibly at the cost of 2888e52347bdSJani Nikula reduced performance. This also guarantees 2889e52347bdSJani Nikula that hot-added devices will work. 2890e52347bdSJani Nikula cbiosize=nn[KMG] The fixed amount of bus space which is 2891e52347bdSJani Nikula reserved for the CardBus bridge's IO window. 2892e52347bdSJani Nikula The default value is 256 bytes. 2893e52347bdSJani Nikula cbmemsize=nn[KMG] The fixed amount of bus space which is 2894e52347bdSJani Nikula reserved for the CardBus bridge's memory 2895e52347bdSJani Nikula window. The default value is 64 megabytes. 2896e52347bdSJani Nikula resource_alignment= 2897e52347bdSJani Nikula Format: 2898e52347bdSJani Nikula [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] 2899e52347bdSJani Nikula [<order of align>@]pci:<vendor>:<device>\ 2900e52347bdSJani Nikula [:<subvendor>:<subdevice>][; ...] 2901e52347bdSJani Nikula Specifies alignment and device to reassign 2902e52347bdSJani Nikula aligned memory resources. 2903e52347bdSJani Nikula If <order of align> is not specified, 2904e52347bdSJani Nikula PAGE_SIZE is used as alignment. 2905e52347bdSJani Nikula PCI-PCI bridge can be specified, if resource 2906e52347bdSJani Nikula windows need to be expanded. 2907e52347bdSJani Nikula To specify the alignment for several 2908e52347bdSJani Nikula instances of a device, the PCI vendor, 2909e52347bdSJani Nikula device, subvendor, and subdevice may be 2910e52347bdSJani Nikula specified, e.g., 4096@pci:8086:9c22:103c:198f 2911e52347bdSJani Nikula ecrc= Enable/disable PCIe ECRC (transaction layer 2912e52347bdSJani Nikula end-to-end CRC checking). 2913e52347bdSJani Nikula bios: Use BIOS/firmware settings. This is the 2914e52347bdSJani Nikula the default. 2915e52347bdSJani Nikula off: Turn ECRC off 2916e52347bdSJani Nikula on: Turn ECRC on. 2917e52347bdSJani Nikula hpiosize=nn[KMG] The fixed amount of bus space which is 2918e52347bdSJani Nikula reserved for hotplug bridge's IO window. 2919e52347bdSJani Nikula Default size is 256 bytes. 2920e52347bdSJani Nikula hpmemsize=nn[KMG] The fixed amount of bus space which is 2921e52347bdSJani Nikula reserved for hotplug bridge's memory window. 2922e52347bdSJani Nikula Default size is 2 megabytes. 2923e52347bdSJani Nikula hpbussize=nn The minimum amount of additional bus numbers 2924e52347bdSJani Nikula reserved for buses below a hotplug bridge. 2925e52347bdSJani Nikula Default is 1. 2926e52347bdSJani Nikula realloc= Enable/disable reallocating PCI bridge resources 2927e52347bdSJani Nikula if allocations done by BIOS are too small to 2928e52347bdSJani Nikula accommodate resources required by all child 2929e52347bdSJani Nikula devices. 2930e52347bdSJani Nikula off: Turn realloc off 2931e52347bdSJani Nikula on: Turn realloc on 2932e52347bdSJani Nikula realloc same as realloc=on 2933e52347bdSJani Nikula noari do not use PCIe ARI. 2934e52347bdSJani Nikula pcie_scan_all Scan all possible PCIe devices. Otherwise we 2935e52347bdSJani Nikula only look for one device below a PCIe downstream 2936e52347bdSJani Nikula port. 2937e52347bdSJani Nikula 2938e52347bdSJani Nikula pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power 2939e52347bdSJani Nikula Management. 2940e52347bdSJani Nikula off Disable ASPM. 2941e52347bdSJani Nikula force Enable ASPM even on devices that claim not to support it. 2942e52347bdSJani Nikula WARNING: Forcing ASPM on may cause system lockups. 2943e52347bdSJani Nikula 2944e52347bdSJani Nikula pcie_hp= [PCIE] PCI Express Hotplug driver options: 2945e52347bdSJani Nikula nomsi Do not use MSI for PCI Express Native Hotplug (this 2946e52347bdSJani Nikula makes all PCIe ports use INTx for hotplug services). 2947e52347bdSJani Nikula 2948e52347bdSJani Nikula pcie_ports= [PCIE] PCIe ports handling: 2949e52347bdSJani Nikula auto Ask the BIOS whether or not to use native PCIe services 2950e52347bdSJani Nikula associated with PCIe ports (PME, hot-plug, AER). Use 2951e52347bdSJani Nikula them only if that is allowed by the BIOS. 2952e52347bdSJani Nikula native Use native PCIe services associated with PCIe ports 2953e52347bdSJani Nikula unconditionally. 2954e52347bdSJani Nikula compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe 2955e52347bdSJani Nikula ports driver. 2956e52347bdSJani Nikula 2957e52347bdSJani Nikula pcie_port_pm= [PCIE] PCIe port power management handling: 2958e52347bdSJani Nikula off Disable power management of all PCIe ports 2959e52347bdSJani Nikula force Forcibly enable power management of all PCIe ports 2960e52347bdSJani Nikula 2961e52347bdSJani Nikula pcie_pme= [PCIE,PM] Native PCIe PME signaling options: 2962e52347bdSJani Nikula nomsi Do not use MSI for native PCIe PME signaling (this makes 2963e52347bdSJani Nikula all PCIe root ports use INTx for all services). 2964e52347bdSJani Nikula 2965e52347bdSJani Nikula pcmv= [HW,PCMCIA] BadgePAD 4 2966e52347bdSJani Nikula 2967e52347bdSJani Nikula pd_ignore_unused 2968e52347bdSJani Nikula [PM] 2969e52347bdSJani Nikula Keep all power-domains already enabled by bootloader on, 2970e52347bdSJani Nikula even if no driver has claimed them. This is useful 2971e52347bdSJani Nikula for debug and development, but should not be 2972e52347bdSJani Nikula needed on a platform with proper driver support. 2973e52347bdSJani Nikula 2974e52347bdSJani Nikula pd. [PARIDE] 2975e52347bdSJani Nikula See Documentation/blockdev/paride.txt. 2976e52347bdSJani Nikula 2977e52347bdSJani Nikula pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at 2978e52347bdSJani Nikula boot time. 2979e52347bdSJani Nikula Format: { 0 | 1 } 2980e52347bdSJani Nikula See arch/parisc/kernel/pdc_chassis.c 2981e52347bdSJani Nikula 2982e52347bdSJani Nikula percpu_alloc= Select which percpu first chunk allocator to use. 2983e52347bdSJani Nikula Currently supported values are "embed" and "page". 2984e52347bdSJani Nikula Archs may support subset or none of the selections. 2985e52347bdSJani Nikula See comments in mm/percpu.c for details on each 2986e52347bdSJani Nikula allocator. This parameter is primarily for debugging 2987e52347bdSJani Nikula and performance comparison. 2988e52347bdSJani Nikula 2989e52347bdSJani Nikula pf. [PARIDE] 2990e52347bdSJani Nikula See Documentation/blockdev/paride.txt. 2991e52347bdSJani Nikula 2992e52347bdSJani Nikula pg. [PARIDE] 2993e52347bdSJani Nikula See Documentation/blockdev/paride.txt. 2994e52347bdSJani Nikula 2995e52347bdSJani Nikula pirq= [SMP,APIC] Manual mp-table setup 2996e52347bdSJani Nikula See Documentation/x86/i386/IO-APIC.txt. 2997e52347bdSJani Nikula 2998e52347bdSJani Nikula plip= [PPT,NET] Parallel port network link 2999e52347bdSJani Nikula Format: { parport<nr> | timid | 0 } 3000e52347bdSJani Nikula See also Documentation/parport.txt. 3001e52347bdSJani Nikula 3002e52347bdSJani Nikula pmtmr= [X86] Manual setup of pmtmr I/O Port. 3003e52347bdSJani Nikula Override pmtimer IOPort with a hex value. 3004e52347bdSJani Nikula e.g. pmtmr=0x508 3005e52347bdSJani Nikula 3006e52347bdSJani Nikula pnp.debug=1 [PNP] 3007e52347bdSJani Nikula Enable PNP debug messages (depends on the 3008e52347bdSJani Nikula CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time 3009e52347bdSJani Nikula via /sys/module/pnp/parameters/debug. We always show 3010e52347bdSJani Nikula current resource usage; turning this on also shows 3011e52347bdSJani Nikula possible settings and some assignment information. 3012e52347bdSJani Nikula 3013e52347bdSJani Nikula pnpacpi= [ACPI] 3014e52347bdSJani Nikula { off } 3015e52347bdSJani Nikula 3016e52347bdSJani Nikula pnpbios= [ISAPNP] 3017e52347bdSJani Nikula { on | off | curr | res | no-curr | no-res } 3018e52347bdSJani Nikula 3019e52347bdSJani Nikula pnp_reserve_irq= 3020e52347bdSJani Nikula [ISAPNP] Exclude IRQs for the autoconfiguration 3021e52347bdSJani Nikula 3022e52347bdSJani Nikula pnp_reserve_dma= 3023e52347bdSJani Nikula [ISAPNP] Exclude DMAs for the autoconfiguration 3024e52347bdSJani Nikula 3025e52347bdSJani Nikula pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration 3026e52347bdSJani Nikula Ranges are in pairs (I/O port base and size). 3027e52347bdSJani Nikula 3028e52347bdSJani Nikula pnp_reserve_mem= 3029e52347bdSJani Nikula [ISAPNP] Exclude memory regions for the 3030e52347bdSJani Nikula autoconfiguration. 3031e52347bdSJani Nikula Ranges are in pairs (memory base and size). 3032e52347bdSJani Nikula 3033e52347bdSJani Nikula ports= [IP_VS_FTP] IPVS ftp helper module 3034e52347bdSJani Nikula Default is 21. 3035e52347bdSJani Nikula Up to 8 (IP_VS_APP_MAX_PORTS) ports 3036e52347bdSJani Nikula may be specified. 3037e52347bdSJani Nikula Format: <port>,<port>.... 3038e52347bdSJani Nikula 3039c3cbd075SBalbir Singh powersave=off [PPC] This option disables power saving features. 3040c3cbd075SBalbir Singh It specifically disables cpuidle and sets the 3041c3cbd075SBalbir Singh platform machine description specific power_save 3042c3cbd075SBalbir Singh function to NULL. On Idle the CPU just reduces 3043c3cbd075SBalbir Singh execution priority. 3044c3cbd075SBalbir Singh 3045e52347bdSJani Nikula ppc_strict_facility_enable 3046e52347bdSJani Nikula [PPC] This option catches any kernel floating point, 3047e52347bdSJani Nikula Altivec, VSX and SPE outside of regions specifically 3048e52347bdSJani Nikula allowed (eg kernel_enable_fpu()/kernel_disable_fpu()). 3049e52347bdSJani Nikula There is some performance impact when enabling this. 3050e52347bdSJani Nikula 3051e52347bdSJani Nikula print-fatal-signals= 3052e52347bdSJani Nikula [KNL] debug: print fatal signals 3053e52347bdSJani Nikula 3054e52347bdSJani Nikula If enabled, warn about various signal handling 3055e52347bdSJani Nikula related application anomalies: too many signals, 3056e52347bdSJani Nikula too many POSIX.1 timers, fatal signals causing a 3057e52347bdSJani Nikula coredump - etc. 3058e52347bdSJani Nikula 3059e52347bdSJani Nikula If you hit the warning due to signal overflow, 3060e52347bdSJani Nikula you might want to try "ulimit -i unlimited". 3061e52347bdSJani Nikula 3062e52347bdSJani Nikula default: off. 3063e52347bdSJani Nikula 3064e52347bdSJani Nikula printk.always_kmsg_dump= 3065e52347bdSJani Nikula Trigger kmsg_dump for cases other than kernel oops or 3066e52347bdSJani Nikula panics 3067e52347bdSJani Nikula Format: <bool> (1/Y/y=enable, 0/N/n=disable) 3068e52347bdSJani Nikula default: disabled 3069e52347bdSJani Nikula 3070e52347bdSJani Nikula printk.devkmsg={on,off,ratelimit} 3071e52347bdSJani Nikula Control writing to /dev/kmsg. 3072e52347bdSJani Nikula on - unlimited logging to /dev/kmsg from userspace 3073e52347bdSJani Nikula off - logging to /dev/kmsg disabled 3074e52347bdSJani Nikula ratelimit - ratelimit the logging 3075e52347bdSJani Nikula Default: ratelimit 3076e52347bdSJani Nikula 3077e52347bdSJani Nikula printk.time= Show timing data prefixed to each printk message line 3078e52347bdSJani Nikula Format: <bool> (1/Y/y=enable, 0/N/n=disable) 3079e52347bdSJani Nikula 3080e52347bdSJani Nikula processor.max_cstate= [HW,ACPI] 3081e52347bdSJani Nikula Limit processor to maximum C-state 3082e52347bdSJani Nikula max_cstate=9 overrides any DMI blacklist limit. 3083e52347bdSJani Nikula 3084e52347bdSJani Nikula processor.nocst [HW,ACPI] 3085e52347bdSJani Nikula Ignore the _CST method to determine C-states, 3086e52347bdSJani Nikula instead using the legacy FADT method 3087e52347bdSJani Nikula 3088e52347bdSJani Nikula profile= [KNL] Enable kernel profiling via /proc/profile 3089e52347bdSJani Nikula Format: [schedule,]<number> 3090e52347bdSJani Nikula Param: "schedule" - profile schedule points. 3091e52347bdSJani Nikula Param: <number> - step/bucket size as a power of 2 for 3092e52347bdSJani Nikula statistical time based profiling. 3093e52347bdSJani Nikula Param: "sleep" - profile D-state sleeping (millisecs). 3094e52347bdSJani Nikula Requires CONFIG_SCHEDSTATS 3095e52347bdSJani Nikula Param: "kvm" - profile VM exits. 3096e52347bdSJani Nikula 3097e52347bdSJani Nikula prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk 3098e52347bdSJani Nikula before loading. 3099e52347bdSJani Nikula See Documentation/blockdev/ramdisk.txt. 3100e52347bdSJani Nikula 3101e52347bdSJani Nikula psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to 3102e52347bdSJani Nikula probe for; one of (bare|imps|exps|lifebook|any). 3103e52347bdSJani Nikula psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports 3104e52347bdSJani Nikula per second. 3105e52347bdSJani Nikula psmouse.resetafter= [HW,MOUSE] 3106e52347bdSJani Nikula Try to reset the device after so many bad packets 3107e52347bdSJani Nikula (0 = never). 3108e52347bdSJani Nikula psmouse.resolution= 3109e52347bdSJani Nikula [HW,MOUSE] Set desired mouse resolution, in dpi. 3110e52347bdSJani Nikula psmouse.smartscroll= 3111e52347bdSJani Nikula [HW,MOUSE] Controls Logitech smartscroll autorepeat. 3112e52347bdSJani Nikula 0 = disabled, 1 = enabled (default). 3113e52347bdSJani Nikula 3114e52347bdSJani Nikula pstore.backend= Specify the name of the pstore backend to use 3115e52347bdSJani Nikula 3116e52347bdSJani Nikula pt. [PARIDE] 3117e52347bdSJani Nikula See Documentation/blockdev/paride.txt. 3118e52347bdSJani Nikula 3119e52347bdSJani Nikula pty.legacy_count= 3120e52347bdSJani Nikula [KNL] Number of legacy pty's. Overwrites compiled-in 3121e52347bdSJani Nikula default number. 3122e52347bdSJani Nikula 3123e52347bdSJani Nikula quiet [KNL] Disable most log messages 3124e52347bdSJani Nikula 3125e52347bdSJani Nikula r128= [HW,DRM] 3126e52347bdSJani Nikula 3127e52347bdSJani Nikula raid= [HW,RAID] 3128e52347bdSJani Nikula See Documentation/admin-guide/md.rst. 3129e52347bdSJani Nikula 3130e52347bdSJani Nikula ramdisk_size= [RAM] Sizes of RAM disks in kilobytes 3131e52347bdSJani Nikula See Documentation/blockdev/ramdisk.txt. 3132e52347bdSJani Nikula 3133e52347bdSJani Nikula rcu_nocbs= [KNL] 3134e52347bdSJani Nikula The argument is a cpu list, as described above. 3135e52347bdSJani Nikula 3136e52347bdSJani Nikula In kernels built with CONFIG_RCU_NOCB_CPU=y, set 3137e52347bdSJani Nikula the specified list of CPUs to be no-callback CPUs. 3138e52347bdSJani Nikula Invocation of these CPUs' RCU callbacks will 3139e52347bdSJani Nikula be offloaded to "rcuox/N" kthreads created for 3140e52347bdSJani Nikula that purpose, where "x" is "b" for RCU-bh, "p" 3141e52347bdSJani Nikula for RCU-preempt, and "s" for RCU-sched, and "N" 3142e52347bdSJani Nikula is the CPU number. This reduces OS jitter on the 3143e52347bdSJani Nikula offloaded CPUs, which can be useful for HPC and 3144e52347bdSJani Nikula real-time workloads. It can also improve energy 3145e52347bdSJani Nikula efficiency for asymmetric multiprocessors. 3146e52347bdSJani Nikula 3147e52347bdSJani Nikula rcu_nocb_poll [KNL] 3148e52347bdSJani Nikula Rather than requiring that offloaded CPUs 3149e52347bdSJani Nikula (specified by rcu_nocbs= above) explicitly 3150e52347bdSJani Nikula awaken the corresponding "rcuoN" kthreads, 3151e52347bdSJani Nikula make these kthreads poll for callbacks. 3152e52347bdSJani Nikula This improves the real-time response for the 3153e52347bdSJani Nikula offloaded CPUs by relieving them of the need to 3154e52347bdSJani Nikula wake up the corresponding kthread, but degrades 3155e52347bdSJani Nikula energy efficiency by requiring that the kthreads 3156e52347bdSJani Nikula periodically wake up to do the polling. 3157e52347bdSJani Nikula 3158e52347bdSJani Nikula rcutree.blimit= [KNL] 3159e52347bdSJani Nikula Set maximum number of finished RCU callbacks to 3160e52347bdSJani Nikula process in one batch. 3161e52347bdSJani Nikula 3162e52347bdSJani Nikula rcutree.dump_tree= [KNL] 3163e52347bdSJani Nikula Dump the structure of the rcu_node combining tree 3164e52347bdSJani Nikula out at early boot. This is used for diagnostic 3165e52347bdSJani Nikula purposes, to verify correct tree setup. 3166e52347bdSJani Nikula 3167e52347bdSJani Nikula rcutree.gp_cleanup_delay= [KNL] 3168e52347bdSJani Nikula Set the number of jiffies to delay each step of 3169e52347bdSJani Nikula RCU grace-period cleanup. This only has effect 3170e52347bdSJani Nikula when CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is set. 3171e52347bdSJani Nikula 3172e52347bdSJani Nikula rcutree.gp_init_delay= [KNL] 3173e52347bdSJani Nikula Set the number of jiffies to delay each step of 3174e52347bdSJani Nikula RCU grace-period initialization. This only has 3175e52347bdSJani Nikula effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT 3176e52347bdSJani Nikula is set. 3177e52347bdSJani Nikula 3178e52347bdSJani Nikula rcutree.gp_preinit_delay= [KNL] 3179e52347bdSJani Nikula Set the number of jiffies to delay each step of 3180e52347bdSJani Nikula RCU grace-period pre-initialization, that is, 3181e52347bdSJani Nikula the propagation of recent CPU-hotplug changes up 3182e52347bdSJani Nikula the rcu_node combining tree. This only has effect 3183e52347bdSJani Nikula when CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is set. 3184e52347bdSJani Nikula 3185e52347bdSJani Nikula rcutree.rcu_fanout_exact= [KNL] 3186e52347bdSJani Nikula Disable autobalancing of the rcu_node combining 3187e52347bdSJani Nikula tree. This is used by rcutorture, and might 3188e52347bdSJani Nikula possibly be useful for architectures having high 3189e52347bdSJani Nikula cache-to-cache transfer latencies. 3190e52347bdSJani Nikula 3191e52347bdSJani Nikula rcutree.rcu_fanout_leaf= [KNL] 3192e52347bdSJani Nikula Change the number of CPUs assigned to each 3193e52347bdSJani Nikula leaf rcu_node structure. Useful for very 3194e52347bdSJani Nikula large systems, which will choose the value 64, 3195e52347bdSJani Nikula and for NUMA systems with large remote-access 3196e52347bdSJani Nikula latencies, which will choose a value aligned 3197e52347bdSJani Nikula with the appropriate hardware boundaries. 3198e52347bdSJani Nikula 3199e52347bdSJani Nikula rcutree.jiffies_till_sched_qs= [KNL] 3200e52347bdSJani Nikula Set required age in jiffies for a 3201e52347bdSJani Nikula given grace period before RCU starts 3202e52347bdSJani Nikula soliciting quiescent-state help from 3203e52347bdSJani Nikula rcu_note_context_switch(). 3204e52347bdSJani Nikula 3205e52347bdSJani Nikula rcutree.jiffies_till_first_fqs= [KNL] 3206e52347bdSJani Nikula Set delay from grace-period initialization to 3207e52347bdSJani Nikula first attempt to force quiescent states. 3208e52347bdSJani Nikula Units are jiffies, minimum value is zero, 3209e52347bdSJani Nikula and maximum value is HZ. 3210e52347bdSJani Nikula 3211e52347bdSJani Nikula rcutree.jiffies_till_next_fqs= [KNL] 3212e52347bdSJani Nikula Set delay between subsequent attempts to force 3213e52347bdSJani Nikula quiescent states. Units are jiffies, minimum 3214e52347bdSJani Nikula value is one, and maximum value is HZ. 3215e52347bdSJani Nikula 3216e52347bdSJani Nikula rcutree.kthread_prio= [KNL,BOOT] 3217e52347bdSJani Nikula Set the SCHED_FIFO priority of the RCU per-CPU 3218e52347bdSJani Nikula kthreads (rcuc/N). This value is also used for 3219e52347bdSJani Nikula the priority of the RCU boost threads (rcub/N) 3220e52347bdSJani Nikula and for the RCU grace-period kthreads (rcu_bh, 3221e52347bdSJani Nikula rcu_preempt, and rcu_sched). If RCU_BOOST is 3222e52347bdSJani Nikula set, valid values are 1-99 and the default is 1 3223e52347bdSJani Nikula (the least-favored priority). Otherwise, when 3224e52347bdSJani Nikula RCU_BOOST is not set, valid values are 0-99 and 3225e52347bdSJani Nikula the default is zero (non-realtime operation). 3226e52347bdSJani Nikula 3227e52347bdSJani Nikula rcutree.rcu_nocb_leader_stride= [KNL] 3228e52347bdSJani Nikula Set the number of NOCB kthread groups, which 3229e52347bdSJani Nikula defaults to the square root of the number of 3230e52347bdSJani Nikula CPUs. Larger numbers reduces the wakeup overhead 3231e52347bdSJani Nikula on the per-CPU grace-period kthreads, but increases 3232e52347bdSJani Nikula that same overhead on each group's leader. 3233e52347bdSJani Nikula 3234e52347bdSJani Nikula rcutree.qhimark= [KNL] 3235e52347bdSJani Nikula Set threshold of queued RCU callbacks beyond which 3236e52347bdSJani Nikula batch limiting is disabled. 3237e52347bdSJani Nikula 3238e52347bdSJani Nikula rcutree.qlowmark= [KNL] 3239e52347bdSJani Nikula Set threshold of queued RCU callbacks below which 3240e52347bdSJani Nikula batch limiting is re-enabled. 3241e52347bdSJani Nikula 3242e52347bdSJani Nikula rcutree.rcu_idle_gp_delay= [KNL] 3243e52347bdSJani Nikula Set wakeup interval for idle CPUs that have 3244e52347bdSJani Nikula RCU callbacks (RCU_FAST_NO_HZ=y). 3245e52347bdSJani Nikula 3246e52347bdSJani Nikula rcutree.rcu_idle_lazy_gp_delay= [KNL] 3247e52347bdSJani Nikula Set wakeup interval for idle CPUs that have 3248e52347bdSJani Nikula only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y). 3249e52347bdSJani Nikula Lazy RCU callbacks are those which RCU can 3250e52347bdSJani Nikula prove do nothing more than free memory. 3251e52347bdSJani Nikula 3252e52347bdSJani Nikula rcuperf.gp_exp= [KNL] 3253e52347bdSJani Nikula Measure performance of expedited synchronous 3254e52347bdSJani Nikula grace-period primitives. 3255e52347bdSJani Nikula 3256e52347bdSJani Nikula rcuperf.holdoff= [KNL] 3257e52347bdSJani Nikula Set test-start holdoff period. The purpose of 3258e52347bdSJani Nikula this parameter is to delay the start of the 3259e52347bdSJani Nikula test until boot completes in order to avoid 3260e52347bdSJani Nikula interference. 3261e52347bdSJani Nikula 3262e52347bdSJani Nikula rcuperf.nreaders= [KNL] 3263e52347bdSJani Nikula Set number of RCU readers. The value -1 selects 3264e52347bdSJani Nikula N, where N is the number of CPUs. A value 3265e52347bdSJani Nikula "n" less than -1 selects N-n+1, where N is again 3266e52347bdSJani Nikula the number of CPUs. For example, -2 selects N 3267e52347bdSJani Nikula (the number of CPUs), -3 selects N+1, and so on. 3268e52347bdSJani Nikula A value of "n" less than or equal to -N selects 3269e52347bdSJani Nikula a single reader. 3270e52347bdSJani Nikula 3271e52347bdSJani Nikula rcuperf.nwriters= [KNL] 3272e52347bdSJani Nikula Set number of RCU writers. The values operate 3273e52347bdSJani Nikula the same as for rcuperf.nreaders. 3274e52347bdSJani Nikula N, where N is the number of CPUs 3275e52347bdSJani Nikula 3276e52347bdSJani Nikula rcuperf.perf_runnable= [BOOT] 3277e52347bdSJani Nikula Start rcuperf running at boot time. 3278e52347bdSJani Nikula 3279e52347bdSJani Nikula rcuperf.shutdown= [KNL] 3280e52347bdSJani Nikula Shut the system down after performance tests 3281e52347bdSJani Nikula complete. This is useful for hands-off automated 3282e52347bdSJani Nikula testing. 3283e52347bdSJani Nikula 3284e52347bdSJani Nikula rcuperf.perf_type= [KNL] 3285e52347bdSJani Nikula Specify the RCU implementation to test. 3286e52347bdSJani Nikula 3287e52347bdSJani Nikula rcuperf.verbose= [KNL] 3288e52347bdSJani Nikula Enable additional printk() statements. 3289e52347bdSJani Nikula 3290e52347bdSJani Nikula rcutorture.cbflood_inter_holdoff= [KNL] 3291e52347bdSJani Nikula Set holdoff time (jiffies) between successive 3292e52347bdSJani Nikula callback-flood tests. 3293e52347bdSJani Nikula 3294e52347bdSJani Nikula rcutorture.cbflood_intra_holdoff= [KNL] 3295e52347bdSJani Nikula Set holdoff time (jiffies) between successive 3296e52347bdSJani Nikula bursts of callbacks within a given callback-flood 3297e52347bdSJani Nikula test. 3298e52347bdSJani Nikula 3299e52347bdSJani Nikula rcutorture.cbflood_n_burst= [KNL] 3300e52347bdSJani Nikula Set the number of bursts making up a given 3301e52347bdSJani Nikula callback-flood test. Set this to zero to 3302e52347bdSJani Nikula disable callback-flood testing. 3303e52347bdSJani Nikula 3304e52347bdSJani Nikula rcutorture.cbflood_n_per_burst= [KNL] 3305e52347bdSJani Nikula Set the number of callbacks to be registered 3306e52347bdSJani Nikula in a given burst of a callback-flood test. 3307e52347bdSJani Nikula 3308e52347bdSJani Nikula rcutorture.fqs_duration= [KNL] 3309e52347bdSJani Nikula Set duration of force_quiescent_state bursts 3310e52347bdSJani Nikula in microseconds. 3311e52347bdSJani Nikula 3312e52347bdSJani Nikula rcutorture.fqs_holdoff= [KNL] 3313e52347bdSJani Nikula Set holdoff time within force_quiescent_state bursts 3314e52347bdSJani Nikula in microseconds. 3315e52347bdSJani Nikula 3316e52347bdSJani Nikula rcutorture.fqs_stutter= [KNL] 3317e52347bdSJani Nikula Set wait time between force_quiescent_state bursts 3318e52347bdSJani Nikula in seconds. 3319e52347bdSJani Nikula 3320e52347bdSJani Nikula rcutorture.gp_cond= [KNL] 3321e52347bdSJani Nikula Use conditional/asynchronous update-side 3322e52347bdSJani Nikula primitives, if available. 3323e52347bdSJani Nikula 3324e52347bdSJani Nikula rcutorture.gp_exp= [KNL] 3325e52347bdSJani Nikula Use expedited update-side primitives, if available. 3326e52347bdSJani Nikula 3327e52347bdSJani Nikula rcutorture.gp_normal= [KNL] 3328e52347bdSJani Nikula Use normal (non-expedited) asynchronous 3329e52347bdSJani Nikula update-side primitives, if available. 3330e52347bdSJani Nikula 3331e52347bdSJani Nikula rcutorture.gp_sync= [KNL] 3332e52347bdSJani Nikula Use normal (non-expedited) synchronous 3333e52347bdSJani Nikula update-side primitives, if available. If all 3334e52347bdSJani Nikula of rcutorture.gp_cond=, rcutorture.gp_exp=, 3335e52347bdSJani Nikula rcutorture.gp_normal=, and rcutorture.gp_sync= 3336e52347bdSJani Nikula are zero, rcutorture acts as if is interpreted 3337e52347bdSJani Nikula they are all non-zero. 3338e52347bdSJani Nikula 3339e52347bdSJani Nikula rcutorture.n_barrier_cbs= [KNL] 3340e52347bdSJani Nikula Set callbacks/threads for rcu_barrier() testing. 3341e52347bdSJani Nikula 3342e52347bdSJani Nikula rcutorture.nfakewriters= [KNL] 3343e52347bdSJani Nikula Set number of concurrent RCU writers. These just 3344e52347bdSJani Nikula stress RCU, they don't participate in the actual 3345e52347bdSJani Nikula test, hence the "fake". 3346e52347bdSJani Nikula 3347e52347bdSJani Nikula rcutorture.nreaders= [KNL] 3348e52347bdSJani Nikula Set number of RCU readers. The value -1 selects 3349e52347bdSJani Nikula N-1, where N is the number of CPUs. A value 3350e52347bdSJani Nikula "n" less than -1 selects N-n-2, where N is again 3351e52347bdSJani Nikula the number of CPUs. For example, -2 selects N 3352e52347bdSJani Nikula (the number of CPUs), -3 selects N+1, and so on. 3353e52347bdSJani Nikula 3354e52347bdSJani Nikula rcutorture.object_debug= [KNL] 3355e52347bdSJani Nikula Enable debug-object double-call_rcu() testing. 3356e52347bdSJani Nikula 3357e52347bdSJani Nikula rcutorture.onoff_holdoff= [KNL] 3358e52347bdSJani Nikula Set time (s) after boot for CPU-hotplug testing. 3359e52347bdSJani Nikula 3360e52347bdSJani Nikula rcutorture.onoff_interval= [KNL] 3361e52347bdSJani Nikula Set time (s) between CPU-hotplug operations, or 3362e52347bdSJani Nikula zero to disable CPU-hotplug testing. 3363e52347bdSJani Nikula 3364e52347bdSJani Nikula rcutorture.shuffle_interval= [KNL] 3365e52347bdSJani Nikula Set task-shuffle interval (s). Shuffling tasks 3366e52347bdSJani Nikula allows some CPUs to go into dyntick-idle mode 3367e52347bdSJani Nikula during the rcutorture test. 3368e52347bdSJani Nikula 3369e52347bdSJani Nikula rcutorture.shutdown_secs= [KNL] 3370e52347bdSJani Nikula Set time (s) after boot system shutdown. This 3371e52347bdSJani Nikula is useful for hands-off automated testing. 3372e52347bdSJani Nikula 3373e52347bdSJani Nikula rcutorture.stall_cpu= [KNL] 3374e52347bdSJani Nikula Duration of CPU stall (s) to test RCU CPU stall 3375e52347bdSJani Nikula warnings, zero to disable. 3376e52347bdSJani Nikula 3377e52347bdSJani Nikula rcutorture.stall_cpu_holdoff= [KNL] 3378e52347bdSJani Nikula Time to wait (s) after boot before inducing stall. 3379e52347bdSJani Nikula 3380e52347bdSJani Nikula rcutorture.stat_interval= [KNL] 3381e52347bdSJani Nikula Time (s) between statistics printk()s. 3382e52347bdSJani Nikula 3383e52347bdSJani Nikula rcutorture.stutter= [KNL] 3384e52347bdSJani Nikula Time (s) to stutter testing, for example, specifying 3385e52347bdSJani Nikula five seconds causes the test to run for five seconds, 3386e52347bdSJani Nikula wait for five seconds, and so on. This tests RCU's 3387e52347bdSJani Nikula ability to transition abruptly to and from idle. 3388e52347bdSJani Nikula 3389e52347bdSJani Nikula rcutorture.test_boost= [KNL] 3390e52347bdSJani Nikula Test RCU priority boosting? 0=no, 1=maybe, 2=yes. 3391e52347bdSJani Nikula "Maybe" means test if the RCU implementation 3392e52347bdSJani Nikula under test support RCU priority boosting. 3393e52347bdSJani Nikula 3394e52347bdSJani Nikula rcutorture.test_boost_duration= [KNL] 3395e52347bdSJani Nikula Duration (s) of each individual boost test. 3396e52347bdSJani Nikula 3397e52347bdSJani Nikula rcutorture.test_boost_interval= [KNL] 3398e52347bdSJani Nikula Interval (s) between each boost test. 3399e52347bdSJani Nikula 3400e52347bdSJani Nikula rcutorture.test_no_idle_hz= [KNL] 3401e52347bdSJani Nikula Test RCU's dyntick-idle handling. See also the 3402e52347bdSJani Nikula rcutorture.shuffle_interval parameter. 3403e52347bdSJani Nikula 3404e52347bdSJani Nikula rcutorture.torture_runnable= [BOOT] 3405e52347bdSJani Nikula Start rcutorture running at boot time. 3406e52347bdSJani Nikula 3407e52347bdSJani Nikula rcutorture.torture_type= [KNL] 3408e52347bdSJani Nikula Specify the RCU implementation to test. 3409e52347bdSJani Nikula 3410e52347bdSJani Nikula rcutorture.verbose= [KNL] 3411e52347bdSJani Nikula Enable additional printk() statements. 3412e52347bdSJani Nikula 3413e52347bdSJani Nikula rcupdate.rcu_cpu_stall_suppress= [KNL] 3414e52347bdSJani Nikula Suppress RCU CPU stall warning messages. 3415e52347bdSJani Nikula 3416e52347bdSJani Nikula rcupdate.rcu_cpu_stall_timeout= [KNL] 3417e52347bdSJani Nikula Set timeout for RCU CPU stall warning messages. 3418e52347bdSJani Nikula 3419e52347bdSJani Nikula rcupdate.rcu_expedited= [KNL] 3420e52347bdSJani Nikula Use expedited grace-period primitives, for 3421e52347bdSJani Nikula example, synchronize_rcu_expedited() instead 3422e52347bdSJani Nikula of synchronize_rcu(). This reduces latency, 3423e52347bdSJani Nikula but can increase CPU utilization, degrade 3424e52347bdSJani Nikula real-time latency, and degrade energy efficiency. 3425e52347bdSJani Nikula No effect on CONFIG_TINY_RCU kernels. 3426e52347bdSJani Nikula 3427e52347bdSJani Nikula rcupdate.rcu_normal= [KNL] 3428e52347bdSJani Nikula Use only normal grace-period primitives, 3429e52347bdSJani Nikula for example, synchronize_rcu() instead of 3430e52347bdSJani Nikula synchronize_rcu_expedited(). This improves 3431e52347bdSJani Nikula real-time latency, CPU utilization, and 3432e52347bdSJani Nikula energy efficiency, but can expose users to 3433e52347bdSJani Nikula increased grace-period latency. This parameter 3434e52347bdSJani Nikula overrides rcupdate.rcu_expedited. No effect on 3435e52347bdSJani Nikula CONFIG_TINY_RCU kernels. 3436e52347bdSJani Nikula 3437e52347bdSJani Nikula rcupdate.rcu_normal_after_boot= [KNL] 3438e52347bdSJani Nikula Once boot has completed (that is, after 3439e52347bdSJani Nikula rcu_end_inkernel_boot() has been invoked), use 3440e52347bdSJani Nikula only normal grace-period primitives. No effect 3441e52347bdSJani Nikula on CONFIG_TINY_RCU kernels. 3442e52347bdSJani Nikula 3443e52347bdSJani Nikula rcupdate.rcu_task_stall_timeout= [KNL] 3444e52347bdSJani Nikula Set timeout in jiffies for RCU task stall warning 3445e52347bdSJani Nikula messages. Disable with a value less than or equal 3446e52347bdSJani Nikula to zero. 3447e52347bdSJani Nikula 3448e52347bdSJani Nikula rcupdate.rcu_self_test= [KNL] 3449e52347bdSJani Nikula Run the RCU early boot self tests 3450e52347bdSJani Nikula 3451e52347bdSJani Nikula rcupdate.rcu_self_test_bh= [KNL] 3452e52347bdSJani Nikula Run the RCU bh early boot self tests 3453e52347bdSJani Nikula 3454e52347bdSJani Nikula rcupdate.rcu_self_test_sched= [KNL] 3455e52347bdSJani Nikula Run the RCU sched early boot self tests 3456e52347bdSJani Nikula 3457e52347bdSJani Nikula rdinit= [KNL] 3458e52347bdSJani Nikula Format: <full_path> 3459e52347bdSJani Nikula Run specified binary instead of /init from the ramdisk, 3460e52347bdSJani Nikula used for early userspace startup. See initrd. 3461e52347bdSJani Nikula 3462e52347bdSJani Nikula reboot= [KNL] 3463e52347bdSJani Nikula Format (x86 or x86_64): 3464e52347bdSJani Nikula [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \ 3465e52347bdSJani Nikula [[,]s[mp]#### \ 3466e52347bdSJani Nikula [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \ 3467e52347bdSJani Nikula [[,]f[orce] 3468e52347bdSJani Nikula Where reboot_mode is one of warm (soft) or cold (hard) or gpio, 3469e52347bdSJani Nikula reboot_type is one of bios, acpi, kbd, triple, efi, or pci, 3470e52347bdSJani Nikula reboot_force is either force or not specified, 3471e52347bdSJani Nikula reboot_cpu is s[mp]#### with #### being the processor 3472e52347bdSJani Nikula to be used for rebooting. 3473e52347bdSJani Nikula 3474e52347bdSJani Nikula relax_domain_level= 3475e52347bdSJani Nikula [KNL, SMP] Set scheduler's default relax_domain_level. 3476e52347bdSJani Nikula See Documentation/cgroup-v1/cpusets.txt. 3477e52347bdSJani Nikula 3478e52347bdSJani Nikula relative_sleep_states= 3479e52347bdSJani Nikula [SUSPEND] Use sleep state labeling where the deepest 3480e52347bdSJani Nikula state available other than hibernation is always "mem". 3481e52347bdSJani Nikula Format: { "0" | "1" } 3482e52347bdSJani Nikula 0 -- Traditional sleep state labels. 3483e52347bdSJani Nikula 1 -- Relative sleep state labels. 3484e52347bdSJani Nikula 3485e52347bdSJani Nikula reserve= [KNL,BUGS] Force the kernel to ignore some iomem area 3486e52347bdSJani Nikula 3487e52347bdSJani Nikula reservetop= [X86-32] 3488e52347bdSJani Nikula Format: nn[KMG] 3489e52347bdSJani Nikula Reserves a hole at the top of the kernel virtual 3490e52347bdSJani Nikula address space. 3491e52347bdSJani Nikula 3492e52347bdSJani Nikula reservelow= [X86] 3493e52347bdSJani Nikula Format: nn[K] 3494e52347bdSJani Nikula Set the amount of memory to reserve for BIOS at 3495e52347bdSJani Nikula the bottom of the address space. 3496e52347bdSJani Nikula 3497e52347bdSJani Nikula reset_devices [KNL] Force drivers to reset the underlying device 3498e52347bdSJani Nikula during initialization. 3499e52347bdSJani Nikula 3500e52347bdSJani Nikula resume= [SWSUSP] 3501e52347bdSJani Nikula Specify the partition device for software suspend 3502e52347bdSJani Nikula Format: 3503e52347bdSJani Nikula {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>} 3504e52347bdSJani Nikula 3505e52347bdSJani Nikula resume_offset= [SWSUSP] 3506e52347bdSJani Nikula Specify the offset from the beginning of the partition 3507e52347bdSJani Nikula given by "resume=" at which the swap header is located, 3508e52347bdSJani Nikula in <PAGE_SIZE> units (needed only for swap files). 3509e52347bdSJani Nikula See Documentation/power/swsusp-and-swap-files.txt 3510e52347bdSJani Nikula 3511e52347bdSJani Nikula resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to 3512e52347bdSJani Nikula read the resume files 3513e52347bdSJani Nikula 3514e52347bdSJani Nikula resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up. 3515e52347bdSJani Nikula Useful for devices that are detected asynchronously 3516e52347bdSJani Nikula (e.g. USB and MMC devices). 3517e52347bdSJani Nikula 3518e52347bdSJani Nikula hibernate= [HIBERNATION] 3519e52347bdSJani Nikula noresume Don't check if there's a hibernation image 3520e52347bdSJani Nikula present during boot. 3521e52347bdSJani Nikula nocompress Don't compress/decompress hibernation images. 3522e52347bdSJani Nikula no Disable hibernation and resume. 3523e52347bdSJani Nikula protect_image Turn on image protection during restoration 3524e52347bdSJani Nikula (that will set all pages holding image data 3525e52347bdSJani Nikula during restoration read-only). 3526e52347bdSJani Nikula 3527e52347bdSJani Nikula retain_initrd [RAM] Keep initrd memory after extraction 3528e52347bdSJani Nikula 3529e52347bdSJani Nikula rfkill.default_state= 3530e52347bdSJani Nikula 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm, 3531e52347bdSJani Nikula etc. communication is blocked by default. 3532e52347bdSJani Nikula 1 Unblocked. 3533e52347bdSJani Nikula 3534e52347bdSJani Nikula rfkill.master_switch_mode= 3535e52347bdSJani Nikula 0 The "airplane mode" button does nothing. 3536e52347bdSJani Nikula 1 The "airplane mode" button toggles between everything 3537e52347bdSJani Nikula blocked and the previous configuration. 3538e52347bdSJani Nikula 2 The "airplane mode" button toggles between everything 3539e52347bdSJani Nikula blocked and everything unblocked. 3540e52347bdSJani Nikula 3541e52347bdSJani Nikula rhash_entries= [KNL,NET] 3542e52347bdSJani Nikula Set number of hash buckets for route cache 3543e52347bdSJani Nikula 3544e52347bdSJani Nikula ro [KNL] Mount root device read-only on boot 3545e52347bdSJani Nikula 3546e52347bdSJani Nikula rodata= [KNL] 3547e52347bdSJani Nikula on Mark read-only kernel memory as read-only (default). 3548e52347bdSJani Nikula off Leave read-only kernel memory writable for debugging. 3549e52347bdSJani Nikula 3550e52347bdSJani Nikula rockchip.usb_uart 3551e52347bdSJani Nikula Enable the uart passthrough on the designated usb port 3552e52347bdSJani Nikula on Rockchip SoCs. When active, the signals of the 3553e52347bdSJani Nikula debug-uart get routed to the D+ and D- pins of the usb 3554e52347bdSJani Nikula port and the regular usb controller gets disabled. 3555e52347bdSJani Nikula 3556e52347bdSJani Nikula root= [KNL] Root filesystem 3557e52347bdSJani Nikula See name_to_dev_t comment in init/do_mounts.c. 3558e52347bdSJani Nikula 3559e52347bdSJani Nikula rootdelay= [KNL] Delay (in seconds) to pause before attempting to 3560e52347bdSJani Nikula mount the root filesystem 3561e52347bdSJani Nikula 3562e52347bdSJani Nikula rootflags= [KNL] Set root filesystem mount option string 3563e52347bdSJani Nikula 3564e52347bdSJani Nikula rootfstype= [KNL] Set root filesystem type 3565e52347bdSJani Nikula 3566e52347bdSJani Nikula rootwait [KNL] Wait (indefinitely) for root device to show up. 3567e52347bdSJani Nikula Useful for devices that are detected asynchronously 3568e52347bdSJani Nikula (e.g. USB and MMC devices). 3569e52347bdSJani Nikula 3570e52347bdSJani Nikula rproc_mem=nn[KMG][@address] 3571e52347bdSJani Nikula [KNL,ARM,CMA] Remoteproc physical memory block. 3572e52347bdSJani Nikula Memory area to be used by remote processor image, 3573e52347bdSJani Nikula managed by CMA. 3574e52347bdSJani Nikula 3575e52347bdSJani Nikula rw [KNL] Mount root device read-write on boot 3576e52347bdSJani Nikula 3577e52347bdSJani Nikula S [KNL] Run init in single mode 3578e52347bdSJani Nikula 3579e52347bdSJani Nikula s390_iommu= [HW,S390] 3580e52347bdSJani Nikula Set s390 IOTLB flushing mode 3581e52347bdSJani Nikula strict 3582e52347bdSJani Nikula With strict flushing every unmap operation will result in 3583e52347bdSJani Nikula an IOTLB flush. Default is lazy flushing before reuse, 3584e52347bdSJani Nikula which is faster. 3585e52347bdSJani Nikula 3586e52347bdSJani Nikula sa1100ir [NET] 3587e52347bdSJani Nikula See drivers/net/irda/sa1100_ir.c. 3588e52347bdSJani Nikula 3589e52347bdSJani Nikula sbni= [NET] Granch SBNI12 leased line adapter 3590e52347bdSJani Nikula 3591e52347bdSJani Nikula sched_debug [KNL] Enables verbose scheduler debug messages. 3592e52347bdSJani Nikula 3593e52347bdSJani Nikula schedstats= [KNL,X86] Enable or disable scheduled statistics. 3594e52347bdSJani Nikula Allowed values are enable and disable. This feature 3595e52347bdSJani Nikula incurs a small amount of overhead in the scheduler 3596e52347bdSJani Nikula but is useful for debugging and performance tuning. 3597e52347bdSJani Nikula 3598e52347bdSJani Nikula skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate 3599e52347bdSJani Nikula xtime_lock contention on larger systems, and/or RCU lock 3600e52347bdSJani Nikula contention on all systems with CONFIG_MAXSMP set. 3601e52347bdSJani Nikula Format: { "0" | "1" } 3602e52347bdSJani Nikula 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1" 3603e52347bdSJani Nikula 1 -- enable. 3604e52347bdSJani Nikula Note: increases power consumption, thus should only be 3605e52347bdSJani Nikula enabled if running jitter sensitive (HPC/RT) workloads. 3606e52347bdSJani Nikula 3607e52347bdSJani Nikula security= [SECURITY] Choose a security module to enable at boot. 3608e52347bdSJani Nikula If this boot parameter is not specified, only the first 3609e52347bdSJani Nikula security module asking for security registration will be 3610e52347bdSJani Nikula loaded. An invalid security module name will be treated 3611e52347bdSJani Nikula as if no module has been chosen. 3612e52347bdSJani Nikula 3613e52347bdSJani Nikula selinux= [SELINUX] Disable or enable SELinux at boot time. 3614e52347bdSJani Nikula Format: { "0" | "1" } 3615e52347bdSJani Nikula See security/selinux/Kconfig help text. 3616e52347bdSJani Nikula 0 -- disable. 3617e52347bdSJani Nikula 1 -- enable. 3618e52347bdSJani Nikula Default value is set via kernel config option. 3619e52347bdSJani Nikula If enabled at boot time, /selinux/disable can be used 3620e52347bdSJani Nikula later to disable prior to initial policy load. 3621e52347bdSJani Nikula 3622e52347bdSJani Nikula apparmor= [APPARMOR] Disable or enable AppArmor at boot time 3623e52347bdSJani Nikula Format: { "0" | "1" } 3624e52347bdSJani Nikula See security/apparmor/Kconfig help text 3625e52347bdSJani Nikula 0 -- disable. 3626e52347bdSJani Nikula 1 -- enable. 3627e52347bdSJani Nikula Default value is set via kernel config option. 3628e52347bdSJani Nikula 3629e52347bdSJani Nikula serialnumber [BUGS=X86-32] 3630e52347bdSJani Nikula 3631e52347bdSJani Nikula shapers= [NET] 3632e52347bdSJani Nikula Maximal number of shapers. 3633e52347bdSJani Nikula 3634e52347bdSJani Nikula simeth= [IA-64] 3635e52347bdSJani Nikula simscsi= 3636e52347bdSJani Nikula 3637e52347bdSJani Nikula slram= [HW,MTD] 3638e52347bdSJani Nikula 3639e52347bdSJani Nikula slab_nomerge [MM] 3640e52347bdSJani Nikula Disable merging of slabs with similar size. May be 3641e52347bdSJani Nikula necessary if there is some reason to distinguish 3642e52347bdSJani Nikula allocs to different slabs. Debug options disable 3643e52347bdSJani Nikula merging on their own. 3644e52347bdSJani Nikula For more information see Documentation/vm/slub.txt. 3645e52347bdSJani Nikula 3646e52347bdSJani Nikula slab_max_order= [MM, SLAB] 3647e52347bdSJani Nikula Determines the maximum allowed order for slabs. 3648e52347bdSJani Nikula A high setting may cause OOMs due to memory 3649e52347bdSJani Nikula fragmentation. Defaults to 1 for systems with 3650e52347bdSJani Nikula more than 32MB of RAM, 0 otherwise. 3651e52347bdSJani Nikula 3652e52347bdSJani Nikula slub_debug[=options[,slabs]] [MM, SLUB] 3653e52347bdSJani Nikula Enabling slub_debug allows one to determine the 3654e52347bdSJani Nikula culprit if slab objects become corrupted. Enabling 3655e52347bdSJani Nikula slub_debug can create guard zones around objects and 3656e52347bdSJani Nikula may poison objects when not in use. Also tracks the 3657e52347bdSJani Nikula last alloc / free. For more information see 3658e52347bdSJani Nikula Documentation/vm/slub.txt. 3659e52347bdSJani Nikula 3660e52347bdSJani Nikula slub_max_order= [MM, SLUB] 3661e52347bdSJani Nikula Determines the maximum allowed order for slabs. 3662e52347bdSJani Nikula A high setting may cause OOMs due to memory 3663e52347bdSJani Nikula fragmentation. For more information see 3664e52347bdSJani Nikula Documentation/vm/slub.txt. 3665e52347bdSJani Nikula 3666e52347bdSJani Nikula slub_min_objects= [MM, SLUB] 3667e52347bdSJani Nikula The minimum number of objects per slab. SLUB will 3668e52347bdSJani Nikula increase the slab order up to slub_max_order to 3669e52347bdSJani Nikula generate a sufficiently large slab able to contain 3670e52347bdSJani Nikula the number of objects indicated. The higher the number 3671e52347bdSJani Nikula of objects the smaller the overhead of tracking slabs 3672e52347bdSJani Nikula and the less frequently locks need to be acquired. 3673e52347bdSJani Nikula For more information see Documentation/vm/slub.txt. 3674e52347bdSJani Nikula 3675e52347bdSJani Nikula slub_min_order= [MM, SLUB] 3676e52347bdSJani Nikula Determines the minimum page order for slabs. Must be 3677e52347bdSJani Nikula lower than slub_max_order. 3678e52347bdSJani Nikula For more information see Documentation/vm/slub.txt. 3679e52347bdSJani Nikula 3680e52347bdSJani Nikula slub_nomerge [MM, SLUB] 3681e52347bdSJani Nikula Same with slab_nomerge. This is supported for legacy. 3682e52347bdSJani Nikula See slab_nomerge for more information. 3683e52347bdSJani Nikula 3684e52347bdSJani Nikula smart2= [HW] 3685e52347bdSJani Nikula Format: <io1>[,<io2>[,...,<io8>]] 3686e52347bdSJani Nikula 3687e52347bdSJani Nikula smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices 3688e52347bdSJani Nikula smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port 3689e52347bdSJani Nikula smsc-ircc2.ircc_sir= [HW] SIR base I/O port 3690e52347bdSJani Nikula smsc-ircc2.ircc_fir= [HW] FIR base I/O port 3691e52347bdSJani Nikula smsc-ircc2.ircc_irq= [HW] IRQ line 3692e52347bdSJani Nikula smsc-ircc2.ircc_dma= [HW] DMA channel 3693e52347bdSJani Nikula smsc-ircc2.ircc_transceiver= [HW] Transceiver type: 3694e52347bdSJani Nikula 0: Toshiba Satellite 1800 (GP data pin select) 3695e52347bdSJani Nikula 1: Fast pin select (default) 3696e52347bdSJani Nikula 2: ATC IRMode 3697e52347bdSJani Nikula 3698e52347bdSJani Nikula smt [KNL,S390] Set the maximum number of threads (logical 3699e52347bdSJani Nikula CPUs) to use per physical CPU on systems capable of 3700e52347bdSJani Nikula symmetric multithreading (SMT). Will be capped to the 3701e52347bdSJani Nikula actual hardware limit. 3702e52347bdSJani Nikula Format: <integer> 3703e52347bdSJani Nikula Default: -1 (no limit) 3704e52347bdSJani Nikula 3705e52347bdSJani Nikula softlockup_panic= 3706e52347bdSJani Nikula [KNL] Should the soft-lockup detector generate panics. 3707e52347bdSJani Nikula Format: <integer> 3708e52347bdSJani Nikula 3709e52347bdSJani Nikula softlockup_all_cpu_backtrace= 3710e52347bdSJani Nikula [KNL] Should the soft-lockup detector generate 3711e52347bdSJani Nikula backtraces on all cpus. 3712e52347bdSJani Nikula Format: <integer> 3713e52347bdSJani Nikula 3714e52347bdSJani Nikula sonypi.*= [HW] Sony Programmable I/O Control Device driver 3715e52347bdSJani Nikula See Documentation/laptops/sonypi.txt 3716e52347bdSJani Nikula 3717e52347bdSJani Nikula spia_io_base= [HW,MTD] 3718e52347bdSJani Nikula spia_fio_base= 3719e52347bdSJani Nikula spia_pedr= 3720e52347bdSJani Nikula spia_peddr= 3721e52347bdSJani Nikula 3722e52347bdSJani Nikula stacktrace [FTRACE] 3723e52347bdSJani Nikula Enabled the stack tracer on boot up. 3724e52347bdSJani Nikula 3725e52347bdSJani Nikula stacktrace_filter=[function-list] 3726e52347bdSJani Nikula [FTRACE] Limit the functions that the stack tracer 3727e52347bdSJani Nikula will trace at boot up. function-list is a comma separated 3728e52347bdSJani Nikula list of functions. This list can be changed at run 3729e52347bdSJani Nikula time by the stack_trace_filter file in the debugfs 3730e52347bdSJani Nikula tracing directory. Note, this enables stack tracing 3731e52347bdSJani Nikula and the stacktrace above is not needed. 3732e52347bdSJani Nikula 3733e52347bdSJani Nikula sti= [PARISC,HW] 3734e52347bdSJani Nikula Format: <num> 3735e52347bdSJani Nikula Set the STI (builtin display/keyboard on the HP-PARISC 3736e52347bdSJani Nikula machines) console (graphic card) which should be used 3737e52347bdSJani Nikula as the initial boot-console. 3738e52347bdSJani Nikula See also comment in drivers/video/console/sticore.c. 3739e52347bdSJani Nikula 3740e52347bdSJani Nikula sti_font= [HW] 3741e52347bdSJani Nikula See comment in drivers/video/console/sticore.c. 3742e52347bdSJani Nikula 3743e52347bdSJani Nikula stifb= [HW] 3744e52347bdSJani Nikula Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] 3745e52347bdSJani Nikula 3746e52347bdSJani Nikula sunrpc.min_resvport= 3747e52347bdSJani Nikula sunrpc.max_resvport= 3748e52347bdSJani Nikula [NFS,SUNRPC] 3749e52347bdSJani Nikula SunRPC servers often require that client requests 3750e52347bdSJani Nikula originate from a privileged port (i.e. a port in the 3751e52347bdSJani Nikula range 0 < portnr < 1024). 3752e52347bdSJani Nikula An administrator who wishes to reserve some of these 3753e52347bdSJani Nikula ports for other uses may adjust the range that the 3754e52347bdSJani Nikula kernel's sunrpc client considers to be privileged 3755e52347bdSJani Nikula using these two parameters to set the minimum and 3756e52347bdSJani Nikula maximum port values. 3757e52347bdSJani Nikula 3758e52347bdSJani Nikula sunrpc.svc_rpc_per_connection_limit= 3759e52347bdSJani Nikula [NFS,SUNRPC] 3760e52347bdSJani Nikula Limit the number of requests that the server will 3761e52347bdSJani Nikula process in parallel from a single connection. 3762e52347bdSJani Nikula The default value is 0 (no limit). 3763e52347bdSJani Nikula 3764e52347bdSJani Nikula sunrpc.pool_mode= 3765e52347bdSJani Nikula [NFS] 3766e52347bdSJani Nikula Control how the NFS server code allocates CPUs to 3767e52347bdSJani Nikula service thread pools. Depending on how many NICs 3768e52347bdSJani Nikula you have and where their interrupts are bound, this 3769e52347bdSJani Nikula option will affect which CPUs will do NFS serving. 3770e52347bdSJani Nikula Note: this parameter cannot be changed while the 3771e52347bdSJani Nikula NFS server is running. 3772e52347bdSJani Nikula 3773e52347bdSJani Nikula auto the server chooses an appropriate mode 3774e52347bdSJani Nikula automatically using heuristics 3775e52347bdSJani Nikula global a single global pool contains all CPUs 3776e52347bdSJani Nikula percpu one pool for each CPU 3777e52347bdSJani Nikula pernode one pool for each NUMA node (equivalent 3778e52347bdSJani Nikula to global on non-NUMA machines) 3779e52347bdSJani Nikula 3780e52347bdSJani Nikula sunrpc.tcp_slot_table_entries= 3781e52347bdSJani Nikula sunrpc.udp_slot_table_entries= 3782e52347bdSJani Nikula [NFS,SUNRPC] 3783e52347bdSJani Nikula Sets the upper limit on the number of simultaneous 3784e52347bdSJani Nikula RPC calls that can be sent from the client to a 3785e52347bdSJani Nikula server. Increasing these values may allow you to 3786e52347bdSJani Nikula improve throughput, but will also increase the 3787e52347bdSJani Nikula amount of memory reserved for use by the client. 3788e52347bdSJani Nikula 3789e52347bdSJani Nikula suspend.pm_test_delay= 3790e52347bdSJani Nikula [SUSPEND] 3791e52347bdSJani Nikula Sets the number of seconds to remain in a suspend test 3792e52347bdSJani Nikula mode before resuming the system (see 3793e52347bdSJani Nikula /sys/power/pm_test). Only available when CONFIG_PM_DEBUG 3794e52347bdSJani Nikula is set. Default value is 5. 3795e52347bdSJani Nikula 3796e52347bdSJani Nikula swapaccount=[0|1] 3797e52347bdSJani Nikula [KNL] Enable accounting of swap in memory resource 3798e52347bdSJani Nikula controller if no parameter or 1 is given or disable 3799e52347bdSJani Nikula it if 0 is given (See Documentation/cgroup-v1/memory.txt) 3800e52347bdSJani Nikula 3801e52347bdSJani Nikula swiotlb= [ARM,IA-64,PPC,MIPS,X86] 3802e52347bdSJani Nikula Format: { <int> | force } 3803e52347bdSJani Nikula <int> -- Number of I/O TLB slabs 3804e52347bdSJani Nikula force -- force using of bounce buffers even if they 3805e52347bdSJani Nikula wouldn't be automatically used by the kernel 3806e52347bdSJani Nikula 3807e52347bdSJani Nikula switches= [HW,M68k] 3808e52347bdSJani Nikula 3809e52347bdSJani Nikula sysfs.deprecated=0|1 [KNL] 3810e52347bdSJani Nikula Enable/disable old style sysfs layout for old udev 3811e52347bdSJani Nikula on older distributions. When this option is enabled 3812e52347bdSJani Nikula very new udev will not work anymore. When this option 3813e52347bdSJani Nikula is disabled (or CONFIG_SYSFS_DEPRECATED not compiled) 3814e52347bdSJani Nikula in older udev will not work anymore. 3815e52347bdSJani Nikula Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in 3816e52347bdSJani Nikula the kernel configuration. 3817e52347bdSJani Nikula 3818e52347bdSJani Nikula sysrq_always_enabled 3819e52347bdSJani Nikula [KNL] 3820e52347bdSJani Nikula Ignore sysrq setting - this boot parameter will 3821e52347bdSJani Nikula neutralize any effect of /proc/sys/kernel/sysrq. 3822e52347bdSJani Nikula Useful for debugging. 3823e52347bdSJani Nikula 3824e52347bdSJani Nikula tcpmhash_entries= [KNL,NET] 3825e52347bdSJani Nikula Set the number of tcp_metrics_hash slots. 3826e52347bdSJani Nikula Default value is 8192 or 16384 depending on total 3827e52347bdSJani Nikula ram pages. This is used to specify the TCP metrics 3828e52347bdSJani Nikula cache size. See Documentation/networking/ip-sysctl.txt 3829e52347bdSJani Nikula "tcp_no_metrics_save" section for more details. 3830e52347bdSJani Nikula 3831e52347bdSJani Nikula tdfx= [HW,DRM] 3832e52347bdSJani Nikula 3833e52347bdSJani Nikula test_suspend= [SUSPEND][,N] 3834e52347bdSJani Nikula Specify "mem" (for Suspend-to-RAM) or "standby" (for 3835e52347bdSJani Nikula standby suspend) or "freeze" (for suspend type freeze) 3836e52347bdSJani Nikula as the system sleep state during system startup with 3837e52347bdSJani Nikula the optional capability to repeat N number of times. 3838e52347bdSJani Nikula The system is woken from this state using a 3839e52347bdSJani Nikula wakeup-capable RTC alarm. 3840e52347bdSJani Nikula 3841e52347bdSJani Nikula thash_entries= [KNL,NET] 3842e52347bdSJani Nikula Set number of hash buckets for TCP connection 3843e52347bdSJani Nikula 3844e52347bdSJani Nikula thermal.act= [HW,ACPI] 3845e52347bdSJani Nikula -1: disable all active trip points in all thermal zones 3846e52347bdSJani Nikula <degrees C>: override all lowest active trip points 3847e52347bdSJani Nikula 3848e52347bdSJani Nikula thermal.crt= [HW,ACPI] 3849e52347bdSJani Nikula -1: disable all critical trip points in all thermal zones 3850e52347bdSJani Nikula <degrees C>: override all critical trip points 3851e52347bdSJani Nikula 3852e52347bdSJani Nikula thermal.nocrt= [HW,ACPI] 3853e52347bdSJani Nikula Set to disable actions on ACPI thermal zone 3854e52347bdSJani Nikula critical and hot trip points. 3855e52347bdSJani Nikula 3856e52347bdSJani Nikula thermal.off= [HW,ACPI] 3857e52347bdSJani Nikula 1: disable ACPI thermal control 3858e52347bdSJani Nikula 3859e52347bdSJani Nikula thermal.psv= [HW,ACPI] 3860e52347bdSJani Nikula -1: disable all passive trip points 3861e52347bdSJani Nikula <degrees C>: override all passive trip points to this 3862e52347bdSJani Nikula value 3863e52347bdSJani Nikula 3864e52347bdSJani Nikula thermal.tzp= [HW,ACPI] 3865e52347bdSJani Nikula Specify global default ACPI thermal zone polling rate 3866e52347bdSJani Nikula <deci-seconds>: poll all this frequency 3867e52347bdSJani Nikula 0: no polling (default) 3868e52347bdSJani Nikula 3869e52347bdSJani Nikula threadirqs [KNL] 3870e52347bdSJani Nikula Force threading of all interrupt handlers except those 3871e52347bdSJani Nikula marked explicitly IRQF_NO_THREAD. 3872e52347bdSJani Nikula 3873e52347bdSJani Nikula tmem [KNL,XEN] 3874e52347bdSJani Nikula Enable the Transcendent memory driver if built-in. 3875e52347bdSJani Nikula 3876e52347bdSJani Nikula tmem.cleancache=0|1 [KNL, XEN] 3877e52347bdSJani Nikula Default is on (1). Disable the usage of the cleancache 3878e52347bdSJani Nikula API to send anonymous pages to the hypervisor. 3879e52347bdSJani Nikula 3880e52347bdSJani Nikula tmem.frontswap=0|1 [KNL, XEN] 3881e52347bdSJani Nikula Default is on (1). Disable the usage of the frontswap 3882e52347bdSJani Nikula API to send swap pages to the hypervisor. If disabled 3883e52347bdSJani Nikula the selfballooning and selfshrinking are force disabled. 3884e52347bdSJani Nikula 3885e52347bdSJani Nikula tmem.selfballooning=0|1 [KNL, XEN] 3886e52347bdSJani Nikula Default is on (1). Disable the driving of swap pages 3887e52347bdSJani Nikula to the hypervisor. 3888e52347bdSJani Nikula 3889e52347bdSJani Nikula tmem.selfshrinking=0|1 [KNL, XEN] 3890e52347bdSJani Nikula Default is on (1). Partial swapoff that immediately 3891e52347bdSJani Nikula transfers pages from Xen hypervisor back to the 3892e52347bdSJani Nikula kernel based on different criteria. 3893e52347bdSJani Nikula 3894e52347bdSJani Nikula topology= [S390] 3895e52347bdSJani Nikula Format: {off | on} 3896e52347bdSJani Nikula Specify if the kernel should make use of the cpu 3897e52347bdSJani Nikula topology information if the hardware supports this. 3898e52347bdSJani Nikula The scheduler will make use of this information and 3899e52347bdSJani Nikula e.g. base its process migration decisions on it. 3900e52347bdSJani Nikula Default is on. 3901e52347bdSJani Nikula 3902e52347bdSJani Nikula topology_updates= [KNL, PPC, NUMA] 3903e52347bdSJani Nikula Format: {off} 3904e52347bdSJani Nikula Specify if the kernel should ignore (off) 3905e52347bdSJani Nikula topology updates sent by the hypervisor to this 3906e52347bdSJani Nikula LPAR. 3907e52347bdSJani Nikula 3908e52347bdSJani Nikula tp720= [HW,PS2] 3909e52347bdSJani Nikula 3910e52347bdSJani Nikula tpm_suspend_pcr=[HW,TPM] 3911e52347bdSJani Nikula Format: integer pcr id 3912e52347bdSJani Nikula Specify that at suspend time, the tpm driver 3913e52347bdSJani Nikula should extend the specified pcr with zeros, 3914e52347bdSJani Nikula as a workaround for some chips which fail to 3915e52347bdSJani Nikula flush the last written pcr on TPM_SaveState. 3916e52347bdSJani Nikula This will guarantee that all the other pcrs 3917e52347bdSJani Nikula are saved. 3918e52347bdSJani Nikula 3919e52347bdSJani Nikula trace_buf_size=nn[KMG] 3920e52347bdSJani Nikula [FTRACE] will set tracing buffer size on each cpu. 3921e52347bdSJani Nikula 3922e52347bdSJani Nikula trace_event=[event-list] 3923e52347bdSJani Nikula [FTRACE] Set and start specified trace events in order 3924e52347bdSJani Nikula to facilitate early boot debugging. The event-list is a 3925e52347bdSJani Nikula comma separated list of trace events to enable. See 3926e52347bdSJani Nikula also Documentation/trace/events.txt 3927e52347bdSJani Nikula 3928e52347bdSJani Nikula trace_options=[option-list] 3929e52347bdSJani Nikula [FTRACE] Enable or disable tracer options at boot. 3930e52347bdSJani Nikula The option-list is a comma delimited list of options 3931e52347bdSJani Nikula that can be enabled or disabled just as if you were 3932e52347bdSJani Nikula to echo the option name into 3933e52347bdSJani Nikula 3934e52347bdSJani Nikula /sys/kernel/debug/tracing/trace_options 3935e52347bdSJani Nikula 3936e52347bdSJani Nikula For example, to enable stacktrace option (to dump the 3937e52347bdSJani Nikula stack trace of each event), add to the command line: 3938e52347bdSJani Nikula 3939e52347bdSJani Nikula trace_options=stacktrace 3940e52347bdSJani Nikula 3941e52347bdSJani Nikula See also Documentation/trace/ftrace.txt "trace options" 3942e52347bdSJani Nikula section. 3943e52347bdSJani Nikula 3944e52347bdSJani Nikula tp_printk[FTRACE] 3945e52347bdSJani Nikula Have the tracepoints sent to printk as well as the 3946e52347bdSJani Nikula tracing ring buffer. This is useful for early boot up 3947e52347bdSJani Nikula where the system hangs or reboots and does not give the 3948e52347bdSJani Nikula option for reading the tracing buffer or performing a 3949e52347bdSJani Nikula ftrace_dump_on_oops. 3950e52347bdSJani Nikula 3951e52347bdSJani Nikula To turn off having tracepoints sent to printk, 3952e52347bdSJani Nikula echo 0 > /proc/sys/kernel/tracepoint_printk 3953e52347bdSJani Nikula Note, echoing 1 into this file without the 3954e52347bdSJani Nikula tracepoint_printk kernel cmdline option has no effect. 3955e52347bdSJani Nikula 3956e52347bdSJani Nikula ** CAUTION ** 3957e52347bdSJani Nikula 3958e52347bdSJani Nikula Having tracepoints sent to printk() and activating high 3959e52347bdSJani Nikula frequency tracepoints such as irq or sched, can cause 3960e52347bdSJani Nikula the system to live lock. 3961e52347bdSJani Nikula 3962e52347bdSJani Nikula traceoff_on_warning 3963e52347bdSJani Nikula [FTRACE] enable this option to disable tracing when a 3964e52347bdSJani Nikula warning is hit. This turns off "tracing_on". Tracing can 3965e52347bdSJani Nikula be enabled again by echoing '1' into the "tracing_on" 3966e52347bdSJani Nikula file located in /sys/kernel/debug/tracing/ 3967e52347bdSJani Nikula 3968e52347bdSJani Nikula This option is useful, as it disables the trace before 3969e52347bdSJani Nikula the WARNING dump is called, which prevents the trace to 3970e52347bdSJani Nikula be filled with content caused by the warning output. 3971e52347bdSJani Nikula 3972e52347bdSJani Nikula This option can also be set at run time via the sysctl 3973e52347bdSJani Nikula option: kernel/traceoff_on_warning 3974e52347bdSJani Nikula 3975e52347bdSJani Nikula transparent_hugepage= 3976e52347bdSJani Nikula [KNL] 3977e52347bdSJani Nikula Format: [always|madvise|never] 3978e52347bdSJani Nikula Can be used to control the default behavior of the system 3979e52347bdSJani Nikula with respect to transparent hugepages. 3980e52347bdSJani Nikula See Documentation/vm/transhuge.txt for more details. 3981e52347bdSJani Nikula 3982e52347bdSJani Nikula tsc= Disable clocksource stability checks for TSC. 3983e52347bdSJani Nikula Format: <string> 3984e52347bdSJani Nikula [x86] reliable: mark tsc clocksource as reliable, this 3985e52347bdSJani Nikula disables clocksource verification at runtime, as well 3986e52347bdSJani Nikula as the stability checks done at bootup. Used to enable 3987e52347bdSJani Nikula high-resolution timer mode on older hardware, and in 3988e52347bdSJani Nikula virtualized environment. 3989e52347bdSJani Nikula [x86] noirqtime: Do not use TSC to do irq accounting. 3990e52347bdSJani Nikula Used to run time disable IRQ_TIME_ACCOUNTING on any 3991e52347bdSJani Nikula platforms where RDTSC is slow and this accounting 3992e52347bdSJani Nikula can add overhead. 3993e52347bdSJani Nikula 3994e52347bdSJani Nikula turbografx.map[2|3]= [HW,JOY] 3995e52347bdSJani Nikula TurboGraFX parallel port interface 3996e52347bdSJani Nikula Format: 3997e52347bdSJani Nikula <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> 3998e52347bdSJani Nikula See also Documentation/input/joystick-parport.txt 3999e52347bdSJani Nikula 4000e52347bdSJani Nikula udbg-immortal [PPC] When debugging early kernel crashes that 4001e52347bdSJani Nikula happen after console_init() and before a proper 4002e52347bdSJani Nikula console driver takes over, this boot options might 4003e52347bdSJani Nikula help "seeing" what's going on. 4004e52347bdSJani Nikula 4005e52347bdSJani Nikula uhash_entries= [KNL,NET] 4006e52347bdSJani Nikula Set number of hash buckets for UDP/UDP-Lite connections 4007e52347bdSJani Nikula 4008e52347bdSJani Nikula uhci-hcd.ignore_oc= 4009e52347bdSJani Nikula [USB] Ignore overcurrent events (default N). 4010e52347bdSJani Nikula Some badly-designed motherboards generate lots of 4011e52347bdSJani Nikula bogus events, for ports that aren't wired to 4012e52347bdSJani Nikula anything. Set this parameter to avoid log spamming. 4013e52347bdSJani Nikula Note that genuine overcurrent events won't be 4014e52347bdSJani Nikula reported either. 4015e52347bdSJani Nikula 4016e52347bdSJani Nikula unknown_nmi_panic 4017e52347bdSJani Nikula [X86] Cause panic on unknown NMI. 4018e52347bdSJani Nikula 4019e52347bdSJani Nikula usbcore.authorized_default= 4020e52347bdSJani Nikula [USB] Default USB device authorization: 4021e52347bdSJani Nikula (default -1 = authorized except for wireless USB, 4022e52347bdSJani Nikula 0 = not authorized, 1 = authorized) 4023e52347bdSJani Nikula 4024e52347bdSJani Nikula usbcore.autosuspend= 4025e52347bdSJani Nikula [USB] The autosuspend time delay (in seconds) used 4026e52347bdSJani Nikula for newly-detected USB devices (default 2). This 4027e52347bdSJani Nikula is the time required before an idle device will be 4028e52347bdSJani Nikula autosuspended. Devices for which the delay is set 4029e52347bdSJani Nikula to a negative value won't be autosuspended at all. 4030e52347bdSJani Nikula 4031e52347bdSJani Nikula usbcore.usbfs_snoop= 4032e52347bdSJani Nikula [USB] Set to log all usbfs traffic (default 0 = off). 4033e52347bdSJani Nikula 4034e52347bdSJani Nikula usbcore.usbfs_snoop_max= 4035e52347bdSJani Nikula [USB] Maximum number of bytes to snoop in each URB 4036e52347bdSJani Nikula (default = 65536). 4037e52347bdSJani Nikula 4038e52347bdSJani Nikula usbcore.blinkenlights= 4039e52347bdSJani Nikula [USB] Set to cycle leds on hubs (default 0 = off). 4040e52347bdSJani Nikula 4041e52347bdSJani Nikula usbcore.old_scheme_first= 4042e52347bdSJani Nikula [USB] Start with the old device initialization 4043e52347bdSJani Nikula scheme (default 0 = off). 4044e52347bdSJani Nikula 4045e52347bdSJani Nikula usbcore.usbfs_memory_mb= 4046e52347bdSJani Nikula [USB] Memory limit (in MB) for buffers allocated by 4047e52347bdSJani Nikula usbfs (default = 16, 0 = max = 2047). 4048e52347bdSJani Nikula 4049e52347bdSJani Nikula usbcore.use_both_schemes= 4050e52347bdSJani Nikula [USB] Try the other device initialization scheme 4051e52347bdSJani Nikula if the first one fails (default 1 = enabled). 4052e52347bdSJani Nikula 4053e52347bdSJani Nikula usbcore.initial_descriptor_timeout= 4054e52347bdSJani Nikula [USB] Specifies timeout for the initial 64-byte 4055e52347bdSJani Nikula USB_REQ_GET_DESCRIPTOR request in milliseconds 4056e52347bdSJani Nikula (default 5000 = 5.0 seconds). 4057e52347bdSJani Nikula 4058e52347bdSJani Nikula usbcore.nousb [USB] Disable the USB subsystem 4059e52347bdSJani Nikula 4060e52347bdSJani Nikula usbhid.mousepoll= 4061e52347bdSJani Nikula [USBHID] The interval which mice are to be polled at. 4062e52347bdSJani Nikula 4063e52347bdSJani Nikula usb-storage.delay_use= 4064e52347bdSJani Nikula [UMS] The delay in seconds before a new device is 4065e52347bdSJani Nikula scanned for Logical Units (default 1). 4066e52347bdSJani Nikula 4067e52347bdSJani Nikula usb-storage.quirks= 4068e52347bdSJani Nikula [UMS] A list of quirks entries to supplement or 4069e52347bdSJani Nikula override the built-in unusual_devs list. List 4070e52347bdSJani Nikula entries are separated by commas. Each entry has 4071e52347bdSJani Nikula the form VID:PID:Flags where VID and PID are Vendor 4072e52347bdSJani Nikula and Product ID values (4-digit hex numbers) and 4073e52347bdSJani Nikula Flags is a set of characters, each corresponding 4074e52347bdSJani Nikula to a common usb-storage quirk flag as follows: 4075e52347bdSJani Nikula a = SANE_SENSE (collect more than 18 bytes 4076e52347bdSJani Nikula of sense data); 4077e52347bdSJani Nikula b = BAD_SENSE (don't collect more than 18 4078e52347bdSJani Nikula bytes of sense data); 4079e52347bdSJani Nikula c = FIX_CAPACITY (decrease the reported 4080e52347bdSJani Nikula device capacity by one sector); 4081e52347bdSJani Nikula d = NO_READ_DISC_INFO (don't use 4082e52347bdSJani Nikula READ_DISC_INFO command); 4083e52347bdSJani Nikula e = NO_READ_CAPACITY_16 (don't use 4084e52347bdSJani Nikula READ_CAPACITY_16 command); 4085e52347bdSJani Nikula f = NO_REPORT_OPCODES (don't use report opcodes 4086e52347bdSJani Nikula command, uas only); 4087e52347bdSJani Nikula g = MAX_SECTORS_240 (don't transfer more than 4088e52347bdSJani Nikula 240 sectors at a time, uas only); 4089e52347bdSJani Nikula h = CAPACITY_HEURISTICS (decrease the 4090e52347bdSJani Nikula reported device capacity by one 4091e52347bdSJani Nikula sector if the number is odd); 4092e52347bdSJani Nikula i = IGNORE_DEVICE (don't bind to this 4093e52347bdSJani Nikula device); 4094e52347bdSJani Nikula j = NO_REPORT_LUNS (don't use report luns 4095e52347bdSJani Nikula command, uas only); 4096e52347bdSJani Nikula l = NOT_LOCKABLE (don't try to lock and 4097e52347bdSJani Nikula unlock ejectable media); 4098e52347bdSJani Nikula m = MAX_SECTORS_64 (don't transfer more 4099e52347bdSJani Nikula than 64 sectors = 32 KB at a time); 4100e52347bdSJani Nikula n = INITIAL_READ10 (force a retry of the 4101e52347bdSJani Nikula initial READ(10) command); 4102e52347bdSJani Nikula o = CAPACITY_OK (accept the capacity 4103e52347bdSJani Nikula reported by the device); 4104e52347bdSJani Nikula p = WRITE_CACHE (the device cache is ON 4105e52347bdSJani Nikula by default); 4106e52347bdSJani Nikula r = IGNORE_RESIDUE (the device reports 4107e52347bdSJani Nikula bogus residue values); 4108e52347bdSJani Nikula s = SINGLE_LUN (the device has only one 4109e52347bdSJani Nikula Logical Unit); 4110e52347bdSJani Nikula t = NO_ATA_1X (don't allow ATA(12) and ATA(16) 4111e52347bdSJani Nikula commands, uas only); 4112e52347bdSJani Nikula u = IGNORE_UAS (don't bind to the uas driver); 4113e52347bdSJani Nikula w = NO_WP_DETECT (don't test whether the 4114e52347bdSJani Nikula medium is write-protected). 4115e52347bdSJani Nikula y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE 4116e52347bdSJani Nikula even if the device claims no cache) 4117e52347bdSJani Nikula Example: quirks=0419:aaf5:rl,0421:0433:rc 4118e52347bdSJani Nikula 4119e52347bdSJani Nikula user_debug= [KNL,ARM] 4120e52347bdSJani Nikula Format: <int> 4121e52347bdSJani Nikula See arch/arm/Kconfig.debug help text. 4122e52347bdSJani Nikula 1 - undefined instruction events 4123e52347bdSJani Nikula 2 - system calls 4124e52347bdSJani Nikula 4 - invalid data aborts 4125e52347bdSJani Nikula 8 - SIGSEGV faults 4126e52347bdSJani Nikula 16 - SIGBUS faults 4127e52347bdSJani Nikula Example: user_debug=31 4128e52347bdSJani Nikula 4129e52347bdSJani Nikula userpte= 4130e52347bdSJani Nikula [X86] Flags controlling user PTE allocations. 4131e52347bdSJani Nikula 4132e52347bdSJani Nikula nohigh = do not allocate PTE pages in 4133e52347bdSJani Nikula HIGHMEM regardless of setting 4134e52347bdSJani Nikula of CONFIG_HIGHPTE. 4135e52347bdSJani Nikula 4136e52347bdSJani Nikula vdso= [X86,SH] 4137e52347bdSJani Nikula On X86_32, this is an alias for vdso32=. Otherwise: 4138e52347bdSJani Nikula 4139e52347bdSJani Nikula vdso=1: enable VDSO (the default) 4140e52347bdSJani Nikula vdso=0: disable VDSO mapping 4141e52347bdSJani Nikula 4142e52347bdSJani Nikula vdso32= [X86] Control the 32-bit vDSO 4143e52347bdSJani Nikula vdso32=1: enable 32-bit VDSO 4144e52347bdSJani Nikula vdso32=0 or vdso32=2: disable 32-bit VDSO 4145e52347bdSJani Nikula 4146e52347bdSJani Nikula See the help text for CONFIG_COMPAT_VDSO for more 4147e52347bdSJani Nikula details. If CONFIG_COMPAT_VDSO is set, the default is 4148e52347bdSJani Nikula vdso32=0; otherwise, the default is vdso32=1. 4149e52347bdSJani Nikula 4150e52347bdSJani Nikula For compatibility with older kernels, vdso32=2 is an 4151e52347bdSJani Nikula alias for vdso32=0. 4152e52347bdSJani Nikula 4153e52347bdSJani Nikula Try vdso32=0 if you encounter an error that says: 4154e52347bdSJani Nikula dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 4155e52347bdSJani Nikula 4156e52347bdSJani Nikula vector= [IA-64,SMP] 4157e52347bdSJani Nikula vector=percpu: enable percpu vector domain 4158e52347bdSJani Nikula 4159e52347bdSJani Nikula video= [FB] Frame buffer configuration 4160e52347bdSJani Nikula See Documentation/fb/modedb.txt. 4161e52347bdSJani Nikula 4162e52347bdSJani Nikula video.brightness_switch_enabled= [0,1] 4163e52347bdSJani Nikula If set to 1, on receiving an ACPI notify event 4164e52347bdSJani Nikula generated by hotkey, video driver will adjust brightness 4165e52347bdSJani Nikula level and then send out the event to user space through 4166e52347bdSJani Nikula the allocated input device; If set to 0, video driver 4167e52347bdSJani Nikula will only send out the event without touching backlight 4168e52347bdSJani Nikula brightness level. 4169e52347bdSJani Nikula default: 1 4170e52347bdSJani Nikula 4171e52347bdSJani Nikula virtio_mmio.device= 4172e52347bdSJani Nikula [VMMIO] Memory mapped virtio (platform) device. 4173e52347bdSJani Nikula 4174e52347bdSJani Nikula <size>@<baseaddr>:<irq>[:<id>] 4175e52347bdSJani Nikula where: 4176e52347bdSJani Nikula <size> := size (can use standard suffixes 4177e52347bdSJani Nikula like K, M and G) 4178e52347bdSJani Nikula <baseaddr> := physical base address 4179e52347bdSJani Nikula <irq> := interrupt number (as passed to 4180e52347bdSJani Nikula request_irq()) 4181e52347bdSJani Nikula <id> := (optional) platform device id 4182e52347bdSJani Nikula example: 4183e52347bdSJani Nikula virtio_mmio.device=1K@0x100b0000:48:7 4184e52347bdSJani Nikula 4185e52347bdSJani Nikula Can be used multiple times for multiple devices. 4186e52347bdSJani Nikula 4187e52347bdSJani Nikula vga= [BOOT,X86-32] Select a particular video mode 4188e52347bdSJani Nikula See Documentation/x86/boot.txt and 4189e52347bdSJani Nikula Documentation/svga.txt. 4190e52347bdSJani Nikula Use vga=ask for menu. 4191e52347bdSJani Nikula This is actually a boot loader parameter; the value is 4192e52347bdSJani Nikula passed to the kernel using a special protocol. 4193e52347bdSJani Nikula 4194e52347bdSJani Nikula vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact 4195e52347bdSJani Nikula size of <nn>. This can be used to increase the 4196e52347bdSJani Nikula minimum size (128MB on x86). It can also be used to 4197e52347bdSJani Nikula decrease the size and leave more room for directly 4198e52347bdSJani Nikula mapped kernel RAM. 4199e52347bdSJani Nikula 4200e52347bdSJani Nikula vmhalt= [KNL,S390] Perform z/VM CP command after system halt. 4201e52347bdSJani Nikula Format: <command> 4202e52347bdSJani Nikula 4203e52347bdSJani Nikula vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. 4204e52347bdSJani Nikula Format: <command> 4205e52347bdSJani Nikula 4206e52347bdSJani Nikula vmpoff= [KNL,S390] Perform z/VM CP command after power off. 4207e52347bdSJani Nikula Format: <command> 4208e52347bdSJani Nikula 4209e52347bdSJani Nikula vsyscall= [X86-64] 4210e52347bdSJani Nikula Controls the behavior of vsyscalls (i.e. calls to 4211e52347bdSJani Nikula fixed addresses of 0xffffffffff600x00 from legacy 4212e52347bdSJani Nikula code). Most statically-linked binaries and older 4213e52347bdSJani Nikula versions of glibc use these calls. Because these 4214e52347bdSJani Nikula functions are at fixed addresses, they make nice 4215e52347bdSJani Nikula targets for exploits that can control RIP. 4216e52347bdSJani Nikula 4217e52347bdSJani Nikula emulate [default] Vsyscalls turn into traps and are 4218e52347bdSJani Nikula emulated reasonably safely. 4219e52347bdSJani Nikula 4220e52347bdSJani Nikula native Vsyscalls are native syscall instructions. 4221e52347bdSJani Nikula This is a little bit faster than trapping 4222e52347bdSJani Nikula and makes a few dynamic recompilers work 4223e52347bdSJani Nikula better than they would in emulation mode. 4224e52347bdSJani Nikula It also makes exploits much easier to write. 4225e52347bdSJani Nikula 4226e52347bdSJani Nikula none Vsyscalls don't work at all. This makes 4227e52347bdSJani Nikula them quite hard to use for exploits but 4228e52347bdSJani Nikula might break your system. 4229e52347bdSJani Nikula 4230e52347bdSJani Nikula vt.color= [VT] Default text color. 4231e52347bdSJani Nikula Format: 0xYX, X = foreground, Y = background. 4232e52347bdSJani Nikula Default: 0x07 = light gray on black. 4233e52347bdSJani Nikula 4234e52347bdSJani Nikula vt.cur_default= [VT] Default cursor shape. 4235e52347bdSJani Nikula Format: 0xCCBBAA, where AA, BB, and CC are the same as 4236e52347bdSJani Nikula the parameters of the <Esc>[?A;B;Cc escape sequence; 4237e52347bdSJani Nikula see VGA-softcursor.txt. Default: 2 = underline. 4238e52347bdSJani Nikula 4239e52347bdSJani Nikula vt.default_blu= [VT] 4240e52347bdSJani Nikula Format: <blue0>,<blue1>,<blue2>,...,<blue15> 4241e52347bdSJani Nikula Change the default blue palette of the console. 4242e52347bdSJani Nikula This is a 16-member array composed of values 4243e52347bdSJani Nikula ranging from 0-255. 4244e52347bdSJani Nikula 4245e52347bdSJani Nikula vt.default_grn= [VT] 4246e52347bdSJani Nikula Format: <green0>,<green1>,<green2>,...,<green15> 4247e52347bdSJani Nikula Change the default green palette of the console. 4248e52347bdSJani Nikula This is a 16-member array composed of values 4249e52347bdSJani Nikula ranging from 0-255. 4250e52347bdSJani Nikula 4251e52347bdSJani Nikula vt.default_red= [VT] 4252e52347bdSJani Nikula Format: <red0>,<red1>,<red2>,...,<red15> 4253e52347bdSJani Nikula Change the default red palette of the console. 4254e52347bdSJani Nikula This is a 16-member array composed of values 4255e52347bdSJani Nikula ranging from 0-255. 4256e52347bdSJani Nikula 4257e52347bdSJani Nikula vt.default_utf8= 4258e52347bdSJani Nikula [VT] 4259e52347bdSJani Nikula Format=<0|1> 4260e52347bdSJani Nikula Set system-wide default UTF-8 mode for all tty's. 4261e52347bdSJani Nikula Default is 1, i.e. UTF-8 mode is enabled for all 4262e52347bdSJani Nikula newly opened terminals. 4263e52347bdSJani Nikula 4264e52347bdSJani Nikula vt.global_cursor_default= 4265e52347bdSJani Nikula [VT] 4266e52347bdSJani Nikula Format=<-1|0|1> 4267e52347bdSJani Nikula Set system-wide default for whether a cursor 4268e52347bdSJani Nikula is shown on new VTs. Default is -1, 4269e52347bdSJani Nikula i.e. cursors will be created by default unless 4270e52347bdSJani Nikula overridden by individual drivers. 0 will hide 4271e52347bdSJani Nikula cursors, 1 will display them. 4272e52347bdSJani Nikula 4273e52347bdSJani Nikula vt.italic= [VT] Default color for italic text; 0-15. 4274e52347bdSJani Nikula Default: 2 = green. 4275e52347bdSJani Nikula 4276e52347bdSJani Nikula vt.underline= [VT] Default color for underlined text; 0-15. 4277e52347bdSJani Nikula Default: 3 = cyan. 4278e52347bdSJani Nikula 4279e52347bdSJani Nikula watchdog timers [HW,WDT] For information on watchdog timers, 4280e52347bdSJani Nikula see Documentation/watchdog/watchdog-parameters.txt 4281e52347bdSJani Nikula or other driver-specific files in the 4282e52347bdSJani Nikula Documentation/watchdog/ directory. 4283e52347bdSJani Nikula 4284e52347bdSJani Nikula workqueue.watchdog_thresh= 4285e52347bdSJani Nikula If CONFIG_WQ_WATCHDOG is configured, workqueue can 4286e52347bdSJani Nikula warn stall conditions and dump internal state to 4287e52347bdSJani Nikula help debugging. 0 disables workqueue stall 4288e52347bdSJani Nikula detection; otherwise, it's the stall threshold 4289e52347bdSJani Nikula duration in seconds. The default value is 30 and 4290e52347bdSJani Nikula it can be updated at runtime by writing to the 4291e52347bdSJani Nikula corresponding sysfs file. 4292e52347bdSJani Nikula 4293e52347bdSJani Nikula workqueue.disable_numa 4294e52347bdSJani Nikula By default, all work items queued to unbound 4295e52347bdSJani Nikula workqueues are affine to the NUMA nodes they're 4296e52347bdSJani Nikula issued on, which results in better behavior in 4297e52347bdSJani Nikula general. If NUMA affinity needs to be disabled for 4298e52347bdSJani Nikula whatever reason, this option can be used. Note 4299e52347bdSJani Nikula that this also can be controlled per-workqueue for 4300e52347bdSJani Nikula workqueues visible under /sys/bus/workqueue/. 4301e52347bdSJani Nikula 4302e52347bdSJani Nikula workqueue.power_efficient 4303e52347bdSJani Nikula Per-cpu workqueues are generally preferred because 4304e52347bdSJani Nikula they show better performance thanks to cache 4305e52347bdSJani Nikula locality; unfortunately, per-cpu workqueues tend to 4306e52347bdSJani Nikula be more power hungry than unbound workqueues. 4307e52347bdSJani Nikula 4308e52347bdSJani Nikula Enabling this makes the per-cpu workqueues which 4309e52347bdSJani Nikula were observed to contribute significantly to power 4310e52347bdSJani Nikula consumption unbound, leading to measurably lower 4311e52347bdSJani Nikula power usage at the cost of small performance 4312e52347bdSJani Nikula overhead. 4313e52347bdSJani Nikula 4314e52347bdSJani Nikula The default value of this parameter is determined by 4315e52347bdSJani Nikula the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT. 4316e52347bdSJani Nikula 4317e52347bdSJani Nikula workqueue.debug_force_rr_cpu 4318e52347bdSJani Nikula Workqueue used to implicitly guarantee that work 4319e52347bdSJani Nikula items queued without explicit CPU specified are put 4320e52347bdSJani Nikula on the local CPU. This guarantee is no longer true 4321e52347bdSJani Nikula and while local CPU is still preferred work items 4322e52347bdSJani Nikula may be put on foreign CPUs. This debug option 4323e52347bdSJani Nikula forces round-robin CPU selection to flush out 4324e52347bdSJani Nikula usages which depend on the now broken guarantee. 4325e52347bdSJani Nikula When enabled, memory and cache locality will be 4326e52347bdSJani Nikula impacted. 4327e52347bdSJani Nikula 4328e52347bdSJani Nikula x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of 4329e52347bdSJani Nikula default x2apic cluster mode on platforms 4330e52347bdSJani Nikula supporting x2apic. 4331e52347bdSJani Nikula 4332e52347bdSJani Nikula x86_intel_mid_timer= [X86-32,APBT] 4333e52347bdSJani Nikula Choose timer option for x86 Intel MID platform. 4334e52347bdSJani Nikula Two valid options are apbt timer only and lapic timer 4335e52347bdSJani Nikula plus one apbt timer for broadcast timer. 4336e52347bdSJani Nikula x86_intel_mid_timer=apbt_only | lapic_and_apbt 4337e52347bdSJani Nikula 4338e52347bdSJani Nikula xen_512gb_limit [KNL,X86-64,XEN] 4339e52347bdSJani Nikula Restricts the kernel running paravirtualized under Xen 4340e52347bdSJani Nikula to use only up to 512 GB of RAM. The reason to do so is 4341e52347bdSJani Nikula crash analysis tools and Xen tools for doing domain 4342e52347bdSJani Nikula save/restore/migration must be enabled to handle larger 4343e52347bdSJani Nikula domains. 4344e52347bdSJani Nikula 4345e52347bdSJani Nikula xen_emul_unplug= [HW,X86,XEN] 4346e52347bdSJani Nikula Unplug Xen emulated devices 4347e52347bdSJani Nikula Format: [unplug0,][unplug1] 4348e52347bdSJani Nikula ide-disks -- unplug primary master IDE devices 4349e52347bdSJani Nikula aux-ide-disks -- unplug non-primary-master IDE devices 4350e52347bdSJani Nikula nics -- unplug network devices 4351e52347bdSJani Nikula all -- unplug all emulated devices (NICs and IDE disks) 4352e52347bdSJani Nikula unnecessary -- unplugging emulated devices is 4353e52347bdSJani Nikula unnecessary even if the host did not respond to 4354e52347bdSJani Nikula the unplug protocol 4355e52347bdSJani Nikula never -- do not unplug even if version check succeeds 4356e52347bdSJani Nikula 4357e52347bdSJani Nikula xen_nopvspin [X86,XEN] 4358e52347bdSJani Nikula Disables the ticketlock slowpath using Xen PV 4359e52347bdSJani Nikula optimizations. 4360e52347bdSJani Nikula 4361e52347bdSJani Nikula xen_nopv [X86] 4362e52347bdSJani Nikula Disables the PV optimizations forcing the HVM guest to 4363e52347bdSJani Nikula run as generic HVM guest with no PV drivers. 4364e52347bdSJani Nikula 4365e52347bdSJani Nikula xirc2ps_cs= [NET,PCMCIA] 4366e52347bdSJani Nikula Format: 4367e52347bdSJani Nikula <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] 4368