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Diffstat (limited to 'Documentation/kernel-parameters.txt')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 262 |
1 files changed, 181 insertions, 81 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 1150444a21a..e0f346d201e 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -100,7 +100,8 @@ parameter is applicable: X86-32 X86-32, aka i386 architecture is enabled. X86-64 X86-64 architecture is enabled. More X86-64 boot options can be found in - Documentation/x86_64/boot-options.txt . + Documentation/x86/x86_64/boot-options.txt . + X86 Either 32bit or 64bit x86 (same as X86-32+X86-64) In addition, the following text indicates that the option: @@ -111,10 +112,10 @@ In addition, the following text indicates that the option: Parameters denoted with BOOT are actually interpreted by the boot loader, and have no meaning to the kernel directly. Do not modify the syntax of boot loader parameters without extreme -need or coordination with <Documentation/i386/boot.txt>. +need or coordination with <Documentation/x86/i386/boot.txt>. There are also arch-specific kernel-parameters not documented here. -See for example <Documentation/x86_64/boot-options.txt>. +See for example <Documentation/x86/x86_64/boot-options.txt>. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that a trailing = on the name of any parameter states that that parameter will @@ -197,40 +198,50 @@ and is between 256 and 4096 characters. It is defined in the file that require a timer override, but don't have HPET - acpi.debug_layer= [HW,ACPI] - Format: <int> - Each bit of the <int> indicates an ACPI debug layer, - 1: enable, 0: disable. It is useful for boot time - debugging. After system has booted up, it can be set - via /sys/module/acpi/parameters/debug_layer. - CONFIG_ACPI_DEBUG must be enabled for this to produce any output. - Available bits (add the numbers together) to enable debug output - for specific parts of the ACPI subsystem: - 0x01 utilities 0x02 hardware 0x04 events 0x08 tables - 0x10 namespace 0x20 parser 0x40 dispatcher - 0x80 executer 0x100 resources 0x200 acpica debugger - 0x400 os services 0x800 acpica disassembler. - The number can be in decimal or prefixed with 0x in hex. - Warning: Many of these options can produce a lot of - output and make your system unusable. Be very careful. - - acpi.debug_level= [HW,ACPI] + acpi_backlight= [HW,ACPI] + acpi_backlight=vendor + acpi_backlight=video + If set to vendor, prefer vendor specific driver + (e.g. thinkpad_acpi, sony_acpi, etc.) instead + of the ACPI video.ko driver. + + acpi_display_output= [HW,ACPI] + acpi_display_output=vendor + acpi_display_output=video + See above. + + acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] + acpi.debug_level= [HW,ACPI,ACPI_DEBUG] Format: <int> - Each bit of the <int> indicates an ACPI debug level, - 1: enable, 0: disable. It is useful for boot time - debugging. After system has booted up, it can be set - via /sys/module/acpi/parameters/debug_level. - CONFIG_ACPI_DEBUG must be enabled for this to produce any output. - Available bits (add the numbers together) to enable different - debug output levels of the ACPI subsystem: - 0x01 error 0x02 warn 0x04 init 0x08 debug object - 0x10 info 0x20 init names 0x40 parse 0x80 load - 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region - 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects - 0x10000 resources 0x20000 user requests 0x40000 package. - The number can be in decimal or prefixed with 0x in hex. - Warning: Many of these options can produce a lot of - output and make your system unusable. Be very careful. + CONFIG_ACPI_DEBUG must be enabled to produce any ACPI + debug output. Bits in debug_layer correspond to a + _COMPONENT in an ACPI source file, e.g., + #define _COMPONENT ACPI_PCI_COMPONENT + Bits in debug_level correspond to a level in + ACPI_DEBUG_PRINT statements, e.g., + ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... + See Documentation/acpi/debug.txt for more information + about debug layers and levels. + + Enable AML "Debug" output, i.e., stores to the Debug + object while interpreting AML: + acpi.debug_layer=0xffffffff acpi.debug_level=0x2 + Enable PCI/PCI interrupt routing info messages: + acpi.debug_layer=0x400000 acpi.debug_level=0x4 + Enable all messages related to ACPI hardware: + acpi.debug_layer=0x2 acpi.debug_level=0xffffffff + + Some values produce so much output that the system is + unusable. The "log_buf_len" parameter may be useful + if you need to capture more output. + + acpi.power_nocheck= [HW,ACPI] + Format: 1/0 enable/disable the check of power state. + On some bogus BIOS the _PSC object/_STA object of + power resource can't return the correct device power + state. In such case it is unneccessary to check its + power state again in power transition. + 1 : disable the power state check acpi_pm_good [X86-32,X86-64] Override the pmtimer bug detection: force the kernel @@ -283,7 +294,14 @@ and is between 256 and 4096 characters. It is defined in the file Possible values are: isolate - enable device isolation (each device, as far as possible, will get its own protection - domain) + domain) [default] + share - put every device behind one IOMMU into the + same protection domain + fullflush - enable flushing of IO/TLB entries when + they are unmapped. Otherwise they are + flushed before they will be reused, which + is a lot of faster + amd_iommu_size= [HW,X86-64] Define the size of the aperture for the AMD IOMMU driver. Possible values are: @@ -463,12 +481,6 @@ and is between 256 and 4096 characters. It is defined in the file Range: 0 - 8192 Default: 64 - disable_8254_timer - enable_8254_timer - [IA32/X86_64] Disable/Enable interrupt 0 timer routing - over the 8254 in addition to over the IO-APIC. The - kernel tries to set a sensible default. - hpet= [X86-32,HPET] option to control HPET usage Format: { enable (default) | disable | force } disable: disable HPET and use PIT instead @@ -619,7 +631,7 @@ and is between 256 and 4096 characters. It is defined in the file digiepca= [HW,SERIAL] See drivers/char/README.epca and - Documentation/digiepca.txt. + Documentation/serial/digiepca.txt. disable_mtrr_cleanup [X86] enable_mtrr_cleanup [X86] @@ -659,11 +671,12 @@ and is between 256 and 4096 characters. It is defined in the file earlyprintk= [X86-32,X86-64,SH,BLACKFIN] earlyprintk=vga earlyprintk=serial[,ttySn[,baudrate]] + earlyprintk=dbgp Append ",keep" to not disable it when the real console takes over. - Only vga or serial at a time, not both. + Only vga or serial or usb debug port at a time. Currently only ttyS0 and ttyS1 are supported. @@ -690,7 +703,7 @@ and is between 256 and 4096 characters. It is defined in the file See Documentation/block/as-iosched.txt and Documentation/block/deadline-iosched.txt for details. - elfcorehdr= [X86-32, X86_64] + elfcorehdr= [IA64,PPC,SH,X86-32,X86_64] Specifies physical address of start of kernel core image elf header. Generally kexec loader will pass this option to capture kernel. @@ -729,7 +742,7 @@ and is between 256 and 4096 characters. It is defined in the file See header of drivers/scsi/fdomain.c. floppy= [HW] - See Documentation/floppy.txt. + See Documentation/blockdev/floppy.txt. force_pal_cache_flush [IA-64] Avoid check_sal_cache_flush which may hang on @@ -796,6 +809,9 @@ and is between 256 and 4096 characters. It is defined in the file Defaults to the default architecture's huge page size if not specified. + hlt [BUGS=ARM,SH] + + i8042.debug [HW] Toggle i8042 debug mode i8042.direct [HW] Put keyboard port into non-translated mode i8042.dumbkbd [HW] Pretend that controller can only read data from keyboard and cannot control its state @@ -964,13 +980,15 @@ and is between 256 and 4096 characters. It is defined in the file Format: <cpu number>,...,<cpu number> or - <cpu number>-<cpu number> (must be a positive range in ascending order) + <cpu number>-<cpu number> + (must be a positive range in ascending order) or a mixture <cpu number>,...,<cpu number>-<cpu number> + This option can be used to specify one or more CPUs to isolate from the general SMP balancing and scheduling - algorithms. The only way to move a process onto or off - an "isolated" CPU is via the CPU affinity syscalls. + algorithms. You can move a process onto or off an + "isolated" CPU via the CPU affinity syscalls or cpuset. <cpu number> begins at 0 and the maximum value is "number of CPUs in system - 1". @@ -1020,6 +1038,10 @@ and is between 256 and 4096 characters. It is defined in the file (only serial suported for now) Format: <serial_device>[,baud] + kmac= [MIPS] korina ethernet MAC address. + Configure the RouterBoard 532 series on-chip + Ethernet adapter MAC address. + l2cr= [PPC] l3cr= [PPC] @@ -1081,7 +1103,7 @@ and is between 256 and 4096 characters. It is defined in the file the same attribute, the last one is used. load_ramdisk= [RAM] List of ramdisks to load from floppy - See Documentation/ramdisk.txt. + See Documentation/blockdev/ramdisk.txt. lockd.nlm_grace_period=P [NFS] Assign grace period. Format: <integer> @@ -1173,8 +1195,8 @@ and is between 256 and 4096 characters. It is defined in the file it is equivalent to "nosmp", which also disables the IO APIC. - max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or - equal to this physical address is ignored. + max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than + or equal to this physical address is ignored. max_luns= [SCSI] Maximum number of LUNs to probe. Should be between 1 and 2^32-1. @@ -1187,7 +1209,7 @@ and is between 256 and 4096 characters. It is defined in the file mce [X86-32] Machine Check Exception - mce=option [X86-64] See Documentation/x86_64/boot-options.txt + mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt md= [HW] RAID subsystems devices and level See Documentation/md.txt. @@ -1206,6 +1228,10 @@ and is between 256 and 4096 characters. It is defined in the file mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel memory. + memchunk=nn[KMG] + [KNL,SH] Allow user to override the default size for + per-device physically contiguous DMA buffers. + memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact E820 memory map, as specified by the user. Such memmap=exactmap lines can be constructed based on @@ -1228,6 +1254,29 @@ and is between 256 and 4096 characters. It is defined in the file or memmap=0x10000$0x18690000 + memory_corruption_check=0/1 [X86] + Some BIOSes seem to corrupt the first 64k of + memory when doing things like suspend/resume. + Setting this option will scan the memory + looking for corruption. Enabling this will + both detect corruption and prevent the kernel + from using the memory being corrupted. + However, its intended as a diagnostic tool; if + repeatable BIOS-originated corruption always + affects the same memory, you can use memmap= + to prevent the kernel from using that memory. + + memory_corruption_check_size=size [X86] + By default it checks for corruption in the low + 64k, making this memory unavailable for normal + use. Use this parameter to scan for + corruption in more or less memory. + + memory_corruption_check_period=seconds [X86] + By default it checks for corruption every 60 + seconds. Use this parameter to check at some + other rate. 0 disables periodic checking. + memtest= [KNL,X86] Enable memtest Format: <integer> range: 0,4 : pattern number @@ -1247,6 +1296,9 @@ and is between 256 and 4096 characters. It is defined in the file mga= [HW,DRM] + min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this + physical address is ignored. + mminit_loglevel= [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this parameter allows control of the logging verbosity for @@ -1365,6 +1417,8 @@ and is between 256 and 4096 characters. It is defined in the file nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. + nodsp [SH] Disable hardware DSP at boot time. + noefi [X86-32,X86-64] Disable EFI runtime services support. noexec [IA-64] @@ -1381,13 +1435,15 @@ and is between 256 and 4096 characters. It is defined in the file noexec32=off: disable non-executable mappings read implies executable mappings + nofpu [SH] Disable hardware FPU at boot time. + nofxsr [BUGS=X86-32] Disables x86 floating point extended register save and restore. The kernel will only save legacy floating-point registers on task switch. noclflush [BUGS=X86] Don't use the CLFLUSH instruction - nohlt [BUGS=ARM] + nohlt [BUGS=ARM,SH] no-hlt [BUGS=X86-32] Tells the kernel that the hlt instruction doesn't work correctly and not to @@ -1404,8 +1460,6 @@ and is between 256 and 4096 characters. It is defined in the file Valid arguments: on, off Default: on - noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing - noirqdebug [X86-32] Disables the code which attempts to detect and disable unhandled interrupt sources. @@ -1425,6 +1479,12 @@ and is between 256 and 4096 characters. It is defined in the file nolapic_timer [X86-32,APIC] Do not use the local APIC timer. + nox2apic [X86-64,APIC] Do not enable x2APIC mode. + + x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of + default x2apic cluster mode on platforms + supporting x2apic. + noltlbs [PPC] Do not use large page/tlb entries for kernel lowmem mapping on PPC40x. @@ -1541,10 +1601,10 @@ and is between 256 and 4096 characters. It is defined in the file pcd. [PARIDE] See header of drivers/block/paride/pcd.c. - See also Documentation/paride.txt. + See also Documentation/blockdev/paride.txt. pci=option[,option...] [PCI] various PCI subsystem options: - off [X86-32] don't probe for the PCI bus + off [X86] don't probe for the PCI bus bios [X86-32] force use of PCI BIOS, don't access the hardware directly. Use this if your machine has a non-standard PCI host bridge. @@ -1552,9 +1612,9 @@ and is between 256 and 4096 characters. It is defined in the file hardware access methods are allowed. Use this if you experience crashes upon bootup and you suspect they are caused by the BIOS. - conf1 [X86-32] Force use of PCI Configuration + conf1 [X86] Force use of PCI Configuration Mechanism 1. - conf2 [X86-32] Force use of PCI Configuration + conf2 [X86] Force use of PCI Configuration Mechanism 2. noaer [PCIE] If the PCIEAER kernel config parameter is enabled, this kernel boot option can be used to @@ -1574,37 +1634,37 @@ and is between 256 and 4096 characters. It is defined in the file this option if the kernel is unable to allocate IRQs or discover secondary PCI buses on your motherboard. - rom [X86-32] Assign address space to expansion ROMs. + rom [X86] Assign address space to expansion ROMs. Use with caution as certain devices share address decoders between ROMs and other resources. - norom [X86-32,X86_64] Do not assign address space to + norom [X86] Do not assign address space to expansion ROMs that do not already have BIOS assigned address ranges. - irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be + irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be assigned automatically to PCI devices. You can make the kernel exclude IRQs of your ISA cards this way. - pirqaddr=0xAAAAA [X86-32] Specify the physical address + pirqaddr=0xAAAAA [X86] Specify the physical address of the PIRQ table (normally generated by the BIOS) if it is outside the F0000h-100000h range. - lastbus=N [X86-32] Scan all buses thru bus #N. Can be + lastbus=N [X86] Scan all buses thru bus #N. Can be useful if the kernel is unable to find your secondary buses and you want to tell it explicitly which ones they are. - assign-busses [X86-32] Always assign all PCI bus + assign-busses [X86] Always assign all PCI bus numbers ourselves, overriding whatever the firmware may have done. - usepirqmask [X86-32] Honor the possible IRQ mask stored + usepirqmask [X86] Honor the possible IRQ mask stored in the BIOS $PIR table. This is needed on some systems with broken BIOSes, notably some HP Pavilion N5400 and Omnibook XE3 notebooks. This will have no effect if ACPI IRQ routing is enabled. - noacpi [X86-32] Do not use ACPI for IRQ routing + noacpi [X86] Do not use ACPI for IRQ routing or for PCI scanning. - use_crs [X86-32] Use _CRS for PCI resource + use_crs [X86] Use _CRS for PCI resource allocation. routeirq Do IRQ routing for all PCI devices. This is normally done in pci_enable_device(), @@ -1633,10 +1693,16 @@ and is between 256 and 4096 characters. It is defined in the file reserved for the CardBus bridge's memory window. The default value is 64 megabytes. + pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power + Management. + off Disable ASPM. + force Enable ASPM even on devices that claim not to support it. + WARNING: Forcing ASPM on may cause system lockups. + pcmv= [HW,PCMCIA] BadgePAD 4 pd. [PARIDE] - See Documentation/paride.txt. + See Documentation/blockdev/paride.txt. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at boot time. @@ -1644,13 +1710,13 @@ and is between 256 and 4096 characters. It is defined in the file See arch/parisc/kernel/pdc_chassis.c pf. [PARIDE] - See Documentation/paride.txt. + See Documentation/blockdev/paride.txt. pg. [PARIDE] - See Documentation/paride.txt. + See Documentation/blockdev/paride.txt. pirq= [SMP,APIC] Manual mp-table setup - See Documentation/i386/IO-APIC.txt. + See Documentation/x86/i386/IO-APIC.txt. plip= [PPT,NET] Parallel port network link Format: { parport<nr> | timid | 0 } @@ -1660,6 +1726,10 @@ and is between 256 and 4096 characters. It is defined in the file Override pmtimer IOPort with a hex value. e.g. pmtmr=0x508 + pnp.debug [PNP] + Enable PNP debug messages. This depends on the + CONFIG_PNP_DEBUG_MESSAGES option. + pnpacpi= [ACPI] { off } @@ -1680,6 +1750,11 @@ and is between 256 and 4096 characters. It is defined in the file autoconfiguration. Ranges are in pairs (memory base and size). + dynamic_printk + Enables pr_debug()/dev_dbg() calls if + CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also + be switched on/off via <debugfs>/dynamic_printk/modules + print-fatal-signals= [KNL] debug: print fatal signals print-fatal-signals=1: print segfault info to @@ -1708,7 +1783,7 @@ and is between 256 and 4096 characters. It is defined in the file prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk before loading. - See Documentation/ramdisk.txt. + See Documentation/blockdev/ramdisk.txt. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to probe for; one of (bare|imps|exps|lifebook|any). @@ -1728,7 +1803,7 @@ and is between 256 and 4096 characters. It is defined in the file <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq> pt. [PARIDE] - See Documentation/paride.txt. + See Documentation/blockdev/paride.txt. pty.legacy_count= [KNL] Number of legacy pty's. Overwrites compiled-in @@ -1742,10 +1817,10 @@ and is between 256 and 4096 characters. It is defined in the file See Documentation/md.txt. ramdisk_blocksize= [RAM] - See Documentation/ramdisk.txt. + See Documentation/blockdev/ramdisk.txt. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes - See Documentation/ramdisk.txt. + See Documentation/blockdev/ramdisk.txt. rcupdate.blimit= [KNL,BOOT] Set maximum number of finished RCU callbacks to process @@ -1882,6 +1957,12 @@ and is between 256 and 4096 characters. It is defined in the file shapers= [NET] Maximal number of shapers. + show_msr= [x86] show boot-time MSR settings + Format: { <integer> } + Show boot-time (BIOS-initialized) MSR settings. + The parameter means the number of CPUs to show, + for example 1 means boot CPU only. + sim710= [SCSI,HW] See header of drivers/scsi/sim710.c. @@ -2071,7 +2152,7 @@ and is between 256 and 4096 characters. It is defined in the file See Documentation/sonypi.txt specialix= [HW,SERIAL] Specialix multi-serial port adapter - See Documentation/specialix.txt. + See Documentation/serial/specialix.txt. spia_io_base= [HW,MTD] spia_fio_base= @@ -2146,7 +2227,7 @@ and is between 256 and 4096 characters. It is defined in the file thermal.crt= [HW,ACPI] -1: disable all critical trip points in all thermal zones - <degrees C>: lower all critical trip points + <degrees C>: override all critical trip points thermal.nocrt= [HW,ACPI] Set to disable actions on ACPI thermal zone @@ -2208,6 +2289,25 @@ and is between 256 and 4096 characters. It is defined in the file autosuspended. Devices for which the delay is set to a negative value won't be autosuspended at all. + usbcore.usbfs_snoop= + [USB] Set to log all usbfs traffic (default 0 = off). + + usbcore.blinkenlights= + [USB] Set to cycle leds on hubs (default 0 = off). + + usbcore.old_scheme_first= + [USB] Start with the old device initialization + scheme (default 0 = off). + + usbcore.use_both_schemes= + [USB] Try the other device initialization scheme + if the first one fails (default 1 = enabled). + + usbcore.initial_descriptor_timeout= + [USB] Specifies timeout for the initial 64-byte + USB_REQ_GET_DESCRIPTOR request in milliseconds + (default 5000 = 5.0 seconds). + usbhid.mousepoll= [USBHID] The interval which mice are to be polled at. @@ -2231,7 +2331,7 @@ and is between 256 and 4096 characters. It is defined in the file See Documentation/fb/modedb.txt. vga= [BOOT,X86-32] Select a particular video mode - See Documentation/i386/boot.txt and + See Documentation/x86/i386/boot.txt and Documentation/svga.txt. Use vga=ask for menu. This is actually a boot loader parameter; the value is |