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840
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1002
1003
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1008
1009
1010
1011
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1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
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1080
1081
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1090
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1100
1101
1102
1103
1104
1105
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1111
1112
1113
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1120
1121
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1123
1124
1125
1126
1127
1128
1129
1130
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1134
1135
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1177
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1190
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1199
1200
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1233
1234
1235
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1371
1372
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1471
1472
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1600
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1657
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1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
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1682
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1684
1685
1686
1687
1688
1689
1690
1691
1692
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1700
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1708
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1720
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1791
1792
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1796
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1800
1801
1802
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1809
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1811
1812
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1815
1816
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1818
1819
1820
1821
1822
1823
1824
1825
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1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
|
Kernel Parameters
~~~~~~~~~~~~~~~~~
The following is a consolidated list of the kernel parameters as implemented
(mostly) by the __setup() macro and sorted into English Dictionary order
(defined as ignoring all punctuation and sorting digits before letters in a
case insensitive manner), and with descriptions where known.
Module parameters for loadable modules are specified only as the
parameter name with optional '=' and value as appropriate, such as:
modprobe usbcore blinkenlights=1
Module parameters for modules that are built into the kernel image
are specified on the kernel command line with the module name plus
'.' plus parameter name, with '=' and value if appropriate, such as:
usbcore.blinkenlights=1
This document may not be entirely up to date and comprehensive. The command
"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
module. Loadable modules, after being loaded into the running kernel, also
reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
parameters may be changed at runtime by the command
"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
The parameters listed below are only valid if certain kernel build options were
enabled and if respective hardware is present. The text in square brackets at
the beginning of each description states the restrictions within which a
parameter is applicable:
ACPI ACPI support is enabled.
AGP AGP (Accelerated Graphics Port) is enabled.
ALSA ALSA sound support is enabled.
APIC APIC support is enabled.
APM Advanced Power Management support is enabled.
AVR32 AVR32 architecture is enabled.
AX25 Appropriate AX.25 support is enabled.
BLACKFIN Blackfin architecture is enabled.
DRM Direct Rendering Management support is enabled.
EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
EFI EFI Partitioning (GPT) is enabled
EIDE EIDE/ATAPI support is enabled.
FB The frame buffer device is enabled.
HW Appropriate hardware is enabled.
IA-64 IA-64 architecture is enabled.
IOSCHED More than one I/O scheduler is enabled.
IP_PNP IP DHCP, BOOTP, or RARP is enabled.
ISAPNP ISA PnP code is enabled.
ISDN Appropriate ISDN support is enabled.
JOY Appropriate joystick support is enabled.
LIBATA Libata driver is enabled
LP Printer support is enabled.
LOOP Loopback device support is enabled.
M68k M68k architecture is enabled.
These options have more detailed description inside of
Documentation/m68k/kernel-options.txt.
MCA MCA bus support is enabled.
MDA MDA console support is enabled.
MOUSE Appropriate mouse support is enabled.
MSI Message Signaled Interrupts (PCI).
MTD MTD (Memory Technology Device) support is enabled.
NET Appropriate network support is enabled.
NUMA NUMA support is enabled.
GENERIC_TIME The generic timeofday code is enabled.
NFS Appropriate NFS support is enabled.
OSS OSS sound support is enabled.
PV_OPS A paravirtualized kernel is enabled.
PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
PARISC The PA-RISC architecture is enabled.
PCI PCI bus support is enabled.
PCIE PCI Express support is enabled.
PCMCIA The PCMCIA subsystem is enabled.
PNP Plug & Play support is enabled.
PPC PowerPC architecture is enabled.
PPT Parallel port support is enabled.
PS2 Appropriate PS/2 support is enabled.
RAM RAM disk support is enabled.
ROOTPLUG The example Root Plug LSM is enabled.
S390 S390 architecture is enabled.
SCSI Appropriate SCSI support is enabled.
A lot of drivers has their options described inside of
Documentation/scsi/.
SECURITY Different security models are enabled.
SELINUX SELinux support is enabled.
SERIAL Serial support is enabled.
SH SuperH architecture is enabled.
SMP The kernel is an SMP kernel.
SPARC Sparc architecture is enabled.
SWSUSP Software suspend (hibernation) is enabled.
SUSPEND System suspend states are enabled.
TS Appropriate touchscreen support is enabled.
USB USB support is enabled.
USBHID USB Human Interface Device support is enabled.
V4L Video For Linux support is enabled.
VGA The VGA console has been enabled.
VT Virtual terminal support is enabled.
WDT Watchdog support is enabled.
XT IBM PC/XT MFM hard disk support is enabled.
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 .
In addition, the following text indicates that the option:
BUGS= Relates to possible processor bugs on the said processor.
KNL Is a kernel start-up parameter.
BOOT Is a boot loader parameter.
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>.
There are also arch-specific kernel-parameters not documented here.
See for example <Documentation/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
be entered as an environment variable, whereas its absence indicates that
it will appear as a kernel argument readable via /proc/cmdline by programs
running once the system is up.
The number of kernel parameters is not limited, but the length of the
complete command line (parameters including spaces etc.) is limited to
a fixed number of characters. This limit depends on the architecture
and is between 256 and 4096 characters. It is defined in the file
./include/asm/setup.h as COMMAND_LINE_SIZE.
acpi= [HW,ACPI,X86-64,i386]
Advanced Configuration and Power Interface
Format: { force | off | ht | strict | noirq }
force -- enable ACPI if default was off
off -- disable ACPI if default was on
noirq -- do not use ACPI for IRQ routing
ht -- run only enough ACPI to enable Hyper Threading
strict -- Be less tolerant of platforms that are not
strictly ACPI specification compliant.
See also Documentation/power/pm.txt, pci=noacpi
acpi_apic_instance= [ACPI, IOAPIC]
Format: <int>
2: use 2nd APIC table, if available
1,0: use 1st APIC table
default: 0
acpi_sleep= [HW,ACPI] Sleep options
Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
See Documentation/power/video.txt for s3_bios and s3_mode.
s3_beep is for debugging; it makes the PC's speaker beep
as soon as the kernel's real-mode entry point is called.
s4_nohwsig prevents ACPI hardware signature from being
used during resume from hibernation.
old_ordering causes the ACPI 1.0 ordering of the _PTS
control method, wrt putting devices into low power
states, to be enforced (the ACPI 2.0 ordering of _PTS is
used by default).
acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Format: { level | edge | high | low }
acpi_irq_balance [HW,ACPI]
ACPI will balance active IRQs
default in APIC mode
acpi_irq_nobalance [HW,ACPI]
ACPI will not move active IRQs (default)
default in PIC mode
acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
use by PCI
Format: <irq>,<irq>...
acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Format: <irq>,<irq>...
acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
Format: To spoof as Windows 98: ="Microsoft Windows"
acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
acpi_osi="string1" # add string1 -- only one string
acpi_osi="!string2" # remove built-in string2
acpi_osi= # disable all strings
acpi_serialize [HW,ACPI] force serialization of AML methods
acpi_skip_timer_override [HW,ACPI]
Recognize and ignore IRQ0/pin2 Interrupt Override.
For broken nForce2 BIOS resulting in XT-PIC timer.
acpi_use_timer_override [HW,ACPI}
Use timer override. For some broken Nvidia NF5 boards
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]
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.
acpi_pm_good [X86-32,X86-64]
Override the pmtimer bug detection: force the kernel
to assume that this machine's pmtimer latches its value
and always returns good values.
agp= [AGP]
{ off | try_unsupported }
off: disable AGP support
try_unsupported: try to drive unsupported chipsets
(may crash computer or cause data corruption)
enable_timer_pin_1 [i386,x86-64]
Enable PIN 1 of APIC timer
Can be useful to work around chipset bugs
(in particular on some ATI chipsets).
The kernel tries to set a reasonable default.
disable_timer_pin_1 [i386,x86-64]
Disable PIN 1 of APIC timer
Can be useful to work around chipset bugs.
ad1848= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<type>
advansys= [HW,SCSI]
See header of drivers/scsi/advansys.c.
advwdt= [HW,WDT] Advantech WDT
Format: <iostart>,<iostop>
aedsp16= [HW,OSS] Audio Excel DSP 16
Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
See also header of sound/oss/aedsp16.c.
aha152x= [HW,SCSI]
See Documentation/scsi/aha152x.txt.
aha1542= [HW,SCSI]
Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
aic7xxx= [HW,SCSI]
See Documentation/scsi/aic7xxx.txt.
aic79xx= [HW,SCSI]
See Documentation/scsi/aic79xx.txt.
amd_iommu= [HW,X86-84]
Pass parameters to the AMD IOMMU driver in the system.
Possible values are:
isolate - enable device isolation (each device, as far
as possible, will get its own 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:
'32M', '64M' (default), '128M', '256M', '512M', '1G'
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
Format: <a>,<b>
See also Documentation/kernel/input/joystick.txt
analog.map= [HW,JOY] Analog joystick and gamepad support
Specifies type or capabilities of an analog joystick
connected to one of 16 gameports
Format: <type1>,<type2>,..<type16>
apc= [HW,SPARC]
Power management functions (SPARCstation-4/5 + deriv.)
Format: noidle
Disable APC CPU standby support. SPARCstation-Fox does
not play well with APC CPU idle - disable it if you have
APC and your system crashes randomly.
apic= [APIC,i386] Advanced Programmable Interrupt Controller
Change the output verbosity whilst booting
Format: { quiet (default) | verbose | debug }
Change the amount of debugging information output
when initialising the APIC and IO-APIC components.
apm= [APM] Advanced Power Management
See header of arch/x86/kernel/apm_32.c.
arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
Format: <io>,<irq>,<nodeID>
ataflop= [HW,M68k]
atarimouse= [HW,MOUSE] Atari Mouse
atascsi= [HW,SCSI] Atari SCSI
atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
EzKey and similar keyboards
atkbd.reset= [HW] Reset keyboard during initialization
atkbd.set= [HW] Select keyboard code set
Format: <int> (2 = AT (default), 3 = PS/2)
atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
keyboards
atkbd.softraw= [HW] Choose between synthetic and real raw mode
Format: <bool> (0 = real, 1 = synthetic (default))
atkbd.softrepeat= [HW]
Use software keyboard repeat
autotest [IA64]
baycom_epp= [HW,AX25]
Format: <io>,<mode>
baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
Format: <io>,<mode>
See header of drivers/net/hamradio/baycom_par.c.
baycom_ser_fdx= [HW,AX25]
BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Format: <io>,<irq>,<mode>[,<baud>]
See header of drivers/net/hamradio/baycom_ser_fdx.c.
baycom_ser_hdx= [HW,AX25]
BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Format: <io>,<irq>,<mode>
See header of drivers/net/hamradio/baycom_ser_hdx.c.
boot_delay= Milliseconds to delay each printk during boot.
Values larger than 10 seconds (10000) are changed to
no delay (0).
Format: integer
bootmem_debug [KNL] Enable bootmem allocator debug messages.
bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
bttv.radio= Most important insmod options are available as
kernel args too.
bttv.pll= See Documentation/video4linux/bttv/Insmod-options
bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
BusLogic= [HW,SCSI]
See drivers/scsi/BusLogic.c, comment before function
BusLogic_ParseDriverOptions().
c101= [NET] Moxa C101 synchronous serial card
cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Sometimes CPU hardware bugs make them report the cache
size incorrectly. The kernel will attempt work arounds
to fix known problems, but for some CPUs it is not
possible to determine what the correct size should be.
This option provides an override for these situations.
security= [SECURITY] Choose a security module to enable at boot.
If this boot parameter is not specified, only the first
security module asking for security registration will be
loaded. An invalid security module name will be treated
as if no module has been chosen.
capability.disable=
[SECURITY] Disable capabilities. This would normally
be used only if an alternative security model is to be
configured. Potentially dangerous and should only be
used if you are entirely sure of the consequences.
ccw_timeout_log [S390]
See Documentation/s390/CommonIO for details.
cgroup_disable= [KNL] Disable a particular controller
Format: {name of the controller(s) to disable}
{Currently supported controllers - "memory"}
checkreqprot [SELINUX] Set initial checkreqprot flag value.
Format: { "0" | "1" }
See security/selinux/Kconfig help text.
0 -- check protection applied by kernel (includes
any implied execute protection).
1 -- check protection requested by application.
Default value is set via a kernel config option.
Value can be changed at runtime via
/selinux/checkreqprot.
cio_ignore= [S390]
See Documentation/s390/CommonIO for details.
clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
[Deprecated]
Forces specified clocksource (if available) to be used
when calculating gettimeofday(). If specified
clocksource is not available, it defaults to PIT.
Format: { pit | tsc | cyclone | pmtmr }
clocksource= [GENERIC_TIME] Override the default clocksource
Format: <string>
Override the default clocksource and use the clocksource
with the name specified.
Some clocksource names to choose from, depending on
the platform:
[all] jiffies (this is the base, fallback clocksource)
[ACPI] acpi_pm
[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
pxa_timer,timer3,32k_counter,timer0_1
[AVR32] avr32
[X86-32] pit,hpet,tsc,vmi-timer;
scx200_hrt on Geode; cyclone on IBM x440
[MIPS] MIPS
[PARISC] cr16
[S390] tod
[SH] SuperH
[SPARC64] tick
[X86-64] hpet,tsc
clearcpuid=BITNUM [X86]
Disable CPUID feature X for the kernel. See
include/asm-x86/cpufeature.h for the valid bit numbers.
Note the Linux specific bits are not necessarily
stable over kernel options, but the vendor specific
ones should be.
Also note that user programs calling CPUID directly
or using the feature without checking anything
will still see it. This just prevents it from
being used by the kernel or shown in /proc/cpuinfo.
Also note the kernel might malfunction if you disable
some critical bits.
code_bytes [IA32/X86_64] How many bytes of object code to print
in an oops report.
Range: 0 - 8192
Default: 64
hpet= [X86-32,HPET] option to control HPET usage
Format: { enable (default) | disable | force }
disable: disable HPET and use PIT instead
force: allow force enabled of undocumented chips (ICH4,
VIA, nVidia)
com20020= [HW,NET] ARCnet - COM20020 chipset
Format:
<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
Format: <io>[,<irq>]
com90xx= [HW,NET]
ARCnet - COM90xx chipset (memory-mapped buffers)
Format: <io>[,<irq>[,<memstart>]]
condev= [HW,S390] console device
conmode=
console= [KNL] Output console device and options.
tty<n> Use the virtual console device <n>.
ttyS<n>[,options]
ttyUSB0[,options]
Use the specified serial port. The options are of
the form "bbbbpnf", where "bbbb" is the baud rate,
"p" is parity ("n", "o", or "e"), "n" is number of
bits, and "f" is flow control ("r" for RTS or
omit it). Default is "9600n8".
See Documentation/serial-console.txt for more
information. See
Documentation/networking/netconsole.txt for an
alternative.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address,
switching to the matching ttyS device later. The
options are the same as for ttyS, above.
If the device connected to the port is not a TTY but a braille
device, prepend "brl," before the device type, for instance
console=brl,ttyS0
For now, only VisioBraille is supported.
earlycon= [KNL] Output early console device and options.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address.
The options are the same as for ttyS, above.
no_console_suspend
[HW] Never suspend the console
Disable suspending of consoles during suspend and
hibernate operations. Once disabled, debugging
messages can reach various consoles while the rest
of the system is being put to sleep (ie, while
debugging driver suspend/resume hooks). This may
not work reliably with all consoles, but is known
to work with serial and VGA consoles.
cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Format:
<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
crashkernel=nn[KMG]@ss[KMG]
[KNL] Reserve a chunk of physical memory to
hold a kernel to switch to with kexec on panic.
crashkernel=range1:size1[,range2:size2,...][@offset]
[KNL] Same as above, but depends on the memory
in the running system. The syntax of range is
start-[end] where start and end are both
a memory unit (amount[KMG]). See also
Documentation/kdump/kdump.txt for a example.
cs4232= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
cs89x0_dma= [HW,NET]
Format: <dma>
cs89x0_media= [HW,NET]
Format: { rj45 | aui | bnc }
dasd= [HW,NET]
See header of drivers/s390/block/dasd_devmap.c.
db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
(one device per port)
Format: <port#>,<type>
See also Documentation/input/joystick-parport.txt
debug [KNL] Enable kernel debugging (events log level).
debug_locks_verbose=
[KNL] verbose self-tests
Format=<0|1>
Print debugging info while doing the locking API
self-tests.
We default to 0 (no extra messages), setting it to
1 will print _a lot_ more information - normally
only useful to kernel developers.
debug_objects [KNL] Enable object debugging
debugpat [X86] Enable PAT debugging
decnet.addr= [HW,NET]
Format: <area>[,<node>]
See also Documentation/networking/decnet.txt.
vt.default_blu= [VT]
Format: <blue0>,<blue1>,<blue2>,...,<blue15>
Change the default blue palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_grn= [VT]
Format: <green0>,<green1>,<green2>,...,<green15>
Change the default green palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_red= [VT]
Format: <red0>,<red1>,<red2>,...,<red15>
Change the default red palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_utf8=
[VT]
Format=<0|1>
Set system-wide default UTF-8 mode for all tty's.
Default is 1, i.e. UTF-8 mode is enabled for all
newly opened terminals.
dhash_entries= [KNL]
Set number of hash buckets for dentry cache.
digi= [HW,SERIAL]
IO parameters + enable/disable command.
digiepca= [HW,SERIAL]
See drivers/char/README.epca and
Documentation/digiepca.txt.
disable_mtrr_cleanup [X86]
enable_mtrr_cleanup [X86]
The kernel tries to adjust MTRR layout from continuous
to discrete, to make X server driver able to add WB
entry later. This parameter enables/disables that.
mtrr_chunk_size=nn[KMG] [X86]
used for mtrr cleanup. It is largest continous chunk
that could hold holes aka. UC entries.
mtrr_gran_size=nn[KMG] [X86]
Used for mtrr cleanup. It is granularity of mtrr block.
Default is 1.
Large value could prevent small alignment from
using up MTRRs.
mtrr_spare_reg_nr=n [X86]
Format: <integer>
Range: 0,7 : spare reg number
Default : 1
Used for mtrr cleanup. It is spare mtrr entries number.
Set to 2 or more if your graphical card needs more.
disable_mtrr_trim [X86, Intel and AMD only]
By default the kernel will trim any uncacheable
memory out of your available memory pool based on
MTRR settings. This parameter disables that behavior,
possibly causing your machine to run very slowly.
dmasound= [HW,OSS] Sound subsystem buffers
dscc4.setup= [NET]
dtc3181e= [HW,SCSI]
earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
earlyprintk=vga
earlyprintk=serial[,ttySn[,baudrate]]
Append ",keep" to not disable it when the real console
takes over.
Only vga or serial at a time, not both.
Currently only ttyS0 and ttyS1 are supported.
Interaction with the standard serial driver is not
very good.
The VGA output is eventually overwritten by the real
console.
eata= [HW,SCSI]
edd= [EDD]
Format: {"off" | "on" | "skip[mbr]"}
eisa_irq_edge= [PARISC,HW]
See header of drivers/parisc/eisa.c.
elanfreq= [X86-32]
See comment before function elanfreq_setup() in
arch/x86/kernel/cpu/cpufreq/elanfreq.c.
elevator= [IOSCHED]
Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
See Documentation/block/as-iosched.txt and
Documentation/block/deadline-iosched.txt for details.
elfcorehdr= [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.
See Documentation/kdump/kdump.txt for details.
enforcing [SELINUX] Set initial enforcing status.
Format: {"0" | "1"}
See security/selinux/Kconfig help text.
0 -- permissive (log only, no denials).
1 -- enforcing (deny and log).
Default value is 0.
Value can be changed at runtime via /selinux/enforce.
es1371= [HW,OSS]
Format: <spdif>,[<nomix>,[<amplifier>]]
See also header of sound/oss/es1371.c.
ether= [HW,NET] Ethernet cards parameters
This option is obsoleted by the "netdev=" option, which
has equivalent usage. See its documentation for details.
eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
Format: <io>[,<irq>]
failslab=
fail_page_alloc=
fail_make_request=[KNL]
General fault injection mechanism.
Format: <interval>,<probability>,<space>,<times>
See also /Documentation/fault-injection/.
fd_mcs= [HW,SCSI]
See header of drivers/scsi/fd_mcs.c.
fdomain= [HW,SCSI]
See header of drivers/scsi/fdomain.c.
floppy= [HW]
See Documentation/floppy.txt.
force_pal_cache_flush
[IA-64] Avoid check_sal_cache_flush which may hang on
buggy SAL_CACHE_FLUSH implementations. Using this
parameter will force ia64_sal_cache_flush to call
ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
gamecon.map[2|3]=
[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
support via parallel port (up to 5 devices per port)
Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
See also Documentation/input/joystick-parport.txt
gamma= [HW,DRM]
gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
Format: off | on
default: on
gdth= [HW,SCSI]
See header of drivers/scsi/gdth.c.
gpt [EFI] Forces disk with valid GPT signature but
invalid Protective MBR to be treated as GPT.
gvp11= [HW,SCSI]
hashdist= [KNL,NUMA] Large hashes allocated during boot
are distributed across NUMA nodes. Defaults on
for IA-64, off otherwise.
Format: 0 | 1 (for off | on)
hcl= [IA-64] SGI's Hardware Graph compatibility layer
hd= [EIDE] (E)IDE hard drive subsystem geometry
Format: <cyl>,<head>,<sect>
highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
size of <nn>. This works even on boxes that have no
highmem otherwise. This also works to reduce highmem
size on bigger boxes.
highres= [KNL] Enable/disable high resolution timer mode.
Valid parameters: "on", "off"
Default: "on"
hisax= [HW,ISDN]
See Documentation/isdn/README.HiSax.
hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
On x86-64 and powerpc, this option can be specified
multiple times interleaved with hugepages= to reserve
huge pages of different sizes. Valid pages sizes on
x86-64 are 2M (when the CPU supports "pse") and 1G
(when the CPU supports the "pdpe1gb" cpuinfo flag)
Note that 1GB pages can only be allocated at boot time
using hugepages= and not freed afterwards.
default_hugepagesz=
[same as hugepagesz=] The size of the default
HugeTLB page size. This is the size represented by
the legacy /proc/ hugepages APIs, used for SHM, and
default size when mounting hugetlbfs filesystems.
Defaults to the default architecture's huge page size
if not specified.
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
(Don't attempt to blink the leds)
i8042.noaux [HW] Don't check for auxiliary (== mouse) port
i8042.nokbd [HW] Don't check/create keyboard port
i8042.noloop [HW] Disable the AUX Loopback command while probing
for the AUX port
i8042.nomux [HW] Don't check presence of an active multiplexing
controller
i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
controllers
i8042.panicblink=
[HW] Frequency with which keyboard LEDs should blink
when kernel panics (default is 0.5 sec)
i8042.reset [HW] Reset the controller during init and cleanup
i8042.unlock [HW] Unlock (ignore) the keylock
i810= [HW,DRM]
i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
indicates that the driver is running on unsupported
hardware.
i8k.force [HW] Activate i8k driver even if SMM BIOS signature
does not match list of supported models.
i8k.power_status
[HW] Report power status in /proc/i8k
(disabled by default)
i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
capability is set.
ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
See Documentation/mca.txt.
icn= [HW,ISDN]
Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
ide= [HW] (E)IDE subsystem
Format: ide=nodma or ide=doubler
See Documentation/ide/ide.txt.
idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
See Documentation/ide/ide.txt.
idle= [X86]
Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
Poll forces a polling idle loop that can slightly improves the performance
of waking up a idle CPU, but will use a lot of power and make the system
run hot. Not recommended.
idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
to not use it because it doesn't save as much power as a normal idle
loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
as idle=poll.
idle=halt. Halt is forced to be used for CPU idle.
In such case C2/C3 won't be used again.
idle=nomwait. Disable mwait for CPU C-states
ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
Claim all unknown PCI IDE storage controllers.
ignore_loglevel [KNL]
Ignore loglevel setting - this will print /all/
kernel messages to the console. Useful for debugging.
ihash_entries= [KNL]
Set number of hash buckets for inode cache.
in2000= [HW,SCSI]
See header of drivers/scsi/in2000.c.
init= [KNL]
Format: <full_path>
Run specified binary instead of /sbin/init as init
process.
initcall_debug [KNL] Trace initcalls as they are executed. Useful
for working out where the kernel is dying during
startup.
initrd= [BOOT] Specify the location of the initial ramdisk
inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
Format: <irq>
inttest= [IA64]
iommu= [x86]
off
force
noforce
biomerge
panic
nopanic
merge
nomerge
forcesac
soft
intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
off
Disable intel iommu driver.
igfx_off [Default Off]
By default, gfx is mapped as normal device. If a gfx
device has a dedicated DMAR unit, the DMAR unit is
bypassed by not enabling DMAR with this option. In
this case, gfx device will use physical address for
DMA.
forcedac [x86_64]
With this option iommu will not optimize to look
for io virtual address below 32 bit forcing dual
address cycle on pci bus for cards supporting greater
than 32 bit addressing. The default is to look
for translation below 32 bit and if not available
then look in the higher range.
strict [Default Off]
With this option on every unmap_single operation will
result in a hardware IOTLB flush operation as opposed
to batching them for performance.
io_delay= [X86-32,X86-64] I/O delay method
0x80
Standard port 0x80 based delay
0xed
Alternate port 0xed based delay (needed on some systems)
udelay
Simple two microseconds delay
none
No delay
io7= [HW] IO7 for Marvel based alpha systems
See comment before marvel_specify_io7 in
arch/alpha/kernel/core_marvel.c.
ip= [IP_PNP]
See Documentation/filesystems/nfsroot.txt.
ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
See comment before ip2_setup() in
drivers/char/ip2/ip2base.c.
ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
See header of drivers/scsi/ips.c.
ports= [IP_VS_FTP] IPVS ftp helper module
Default is 21.
Up to 8 (IP_VS_APP_MAX_PORTS) ports
may be specified.
Format: <port>,<port>....
irqfixup [HW]
When an interrupt is not handled search all handlers
for it. Intended to get systems with badly broken
firmware running.
irqpoll [HW]
When an interrupt is not handled search all handlers
for it. Also check all handlers each timer
interrupt. Intended to get systems with badly broken
firmware running.
isapnp= [ISAPNP]
Format: <RDP>,<reset>,<pci_scan>,<verbosity>
isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Format:
<cpu number>,...,<cpu number>
or
<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.
<cpu number> begins at 0 and the maximum value is
"number of CPUs in system - 1".
This option is the preferred way to isolate CPUs. The
alternative -- manually setting the CPU mask of all
tasks in the system -- can cause problems and
suboptimal load balancer performance.
iucv= [HW,NET]
js= [HW,JOY] Analog joystick
See Documentation/input/joystick.txt.
kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
specifies the amount of memory usable by the kernel
for non-movable allocations. The requested amount is
spread evenly throughout all nodes in the system. The
remaining memory in each node is used for Movable
pages. In the event, a node is too small to have both
kernelcore and Movable pages, kernelcore pages will
take priority and other nodes will have a larger number
of kernelcore pages. The Movable zone is used for the
allocation of pages that may be reclaimed or moved
by the page migration subsystem. This means that
HugeTLB pages may not be allocated from this zone.
Note that allocations like PTEs-from-HighMem still
use the HighMem zone if it exists, and the Normal
zone if it does not.
movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
is similar to kernelcore except it specifies the
amount of memory used for migratable allocations.
If both kernelcore and movablecore is specified,
then kernelcore will be at *least* the specified
value but may be more. If movablecore on its own
is specified, the administrator must be careful
that the amount of memory usable for all allocations
is not too small.
keepinitrd [HW,ARM]
kstack=N [X86-32,X86-64] Print N words from the kernel stack
in oops dumps.
kgdboc= [HW] kgdb over consoles.
Requires a tty driver that supports console polling.
(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]
lapic [X86-32,APIC] Enable the local APIC even if BIOS
disabled it.
lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
C2 power state.
libata.dma= [LIBATA] DMA control
libata.dma=0 Disable all PATA and SATA DMA
libata.dma=1 PATA and SATA Disk DMA only
libata.dma=2 ATAPI (CDROM) DMA only
libata.dma=4 Compact Flash DMA only
Combinations also work, so libata.dma=3 enables DMA
for disks and CDROMs, but not CFs.
libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
when set.
Format: <int>
libata.force= [LIBATA] Force configurations. The format is comma
separated list of "[ID:]VAL" where ID is
PORT[:DEVICE]. PORT and DEVICE are decimal numbers
matching port, link or device. Basically, it matches
the ATA ID string printed on console by libata. If
the whole ID part is omitted, the last PORT and DEVICE
values are used. If ID hasn't been specified yet, the
configuration applies to all ports, links and devices.
If only DEVICE is omitted, the parameter applies to
the port and all links and devices behind it. DEVICE
number of 0 either selects the first device or the
first fan-out link behind PMP device. It does not
select the host link. DEVICE number of 15 selects the
host link and device attached to it.
The VAL specifies the configuration to force. As long
as there's no ambiguity shortcut notation is allowed.
For example, both 1.5 and 1.5G would work for 1.5Gbps.
The following configurations can be forced.
* Cable type: 40c, 80c, short40c, unk, ign or sata.
Any ID with matching PORT is used.
* SATA link speed limit: 1.5Gbps or 3.0Gbps.
* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
udma[/][16,25,33,44,66,100,133] notation is also
allowed.
* [no]ncq: Turn on or off NCQ.
* nohrst, nosrst, norst: suppress hard, soft
and both resets.
If there are multiple matching configurations changing
the same attribute, the last one is used.
load_ramdisk= [RAM] List of ramdisks to load from floppy
See Documentation/ramdisk.txt.
lockd.nlm_grace_period=P [NFS] Assign grace period.
Format: <integer>
lockd.nlm_tcpport=N [NFS] Assign TCP port.
Format: <integer>
lockd.nlm_timeout=T [NFS] Assign timeout value.
Format: <integer>
lockd.nlm_udpport=M [NFS] Assign UDP port.
Format: <integer>
logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
Format: <irq>
loglevel= All Kernel Messages with a loglevel smaller than the
console loglevel will be printed to the console. It can
also be changed with klogd or other programs. The
loglevels are defined as follows:
0 (KERN_EMERG) system is unusable
1 (KERN_ALERT) action must be taken immediately
2 (KERN_CRIT) critical conditions
3 (KERN_ERR) error conditions
4 (KERN_WARNING) warning conditions
5 (KERN_NOTICE) normal but significant condition
6 (KERN_INFO) informational
7 (KERN_DEBUG) debug-level messages
log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Format: { n | nk | nM }
n must be a power of two. The default size
is set in the kernel config file.
logo.nologo [FB] Disables display of the built-in Linux logo.
This may be used to provide more screen space for
kernel log messages and is useful when debugging
kernel boot problems.
lp=0 [LP] Specify parallel ports to use, e.g,
lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
lp=reset first parallel port). 'lp=0' disables the
lp=auto printer driver. 'lp=reset' (which can be
specified in addition to the ports) causes
attached printers to be reset. Using
lp=port1,port2,... specifies the parallel ports
to associate lp devices with, starting with
lp0. A port specification may be 'none' to skip
that lp device, or a parport name such as
'parport0'. Specifying 'lp=auto' instead of a
port specification list means that device IDs
from each port should be examined, to see if
an IEEE 1284-compliant printer is attached; if
so, the driver will manage that printer.
See also header of drivers/char/lp.c.
lpj=n [KNL]
Sets loops_per_jiffy to given constant, thus avoiding
time-consuming boot-time autodetection (up to 250 ms per
CPU). 0 enables autodetection (default). To determine
the correct value for your kernel, boot with normal
autodetection and see what value is printed. Note that
on SMP systems the preset will be applied to all CPUs,
which is likely to cause problems if your CPUs need
significantly divergent settings. An incorrect value
will cause delays in the kernel to be wrong, leading to
unpredictable I/O errors and other breakage. Although
unlikely, in the extreme case this might damage your
hardware.
ltpc= [NET]
Format: <io>,<irq>,<dma>
mac5380= [HW,SCSI] Format:
<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
machvec= [IA64] Force the use of a particular machine-vector
(machvec) in a generic kernel.
Example: machvec=hpzx1_swiotlb
max_loop= [LOOP] Maximum number of loopback devices that can
be mounted
Format: <1-256>
maxcpus= [SMP] Maximum number of processors that an SMP kernel
should make use of. maxcpus=n : n >= 0 limits the
kernel to using 'n' processors. n=0 is a special case,
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_luns= [SCSI] Maximum number of LUNs to probe.
Should be between 1 and 2^32-1.
max_report_luns=
[SCSI] Maximum number of LUNs received.
Should be between 1 and 16384.
mcatest= [IA-64]
mce [X86-32] Machine Check Exception
mce=option [X86-64] See Documentation/x86_64/boot-options.txt
md= [HW] RAID subsystems devices and level
See Documentation/md.txt.
mdacon= [MDA]
Format: <first>,<last>
Specifies range of consoles to be captured by the MDA.
mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
Amount of memory to be used when the kernel is not able
to see the whole system memory or for test.
[X86-32] Use together with memmap= to avoid physical
address space collisions. Without memmap= PCI devices
could be placed at addresses belonging to unused RAM.
mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
memory.
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
BIOS output or other requirements. See the memmap=nn@ss
option description.
memmap=nn[KMG]@ss[KMG]
[KNL] Force usage of a specific region of memory
Region of memory to be used, from ss to ss+nn.
memmap=nn[KMG]#ss[KMG]
[KNL,ACPI] Mark specific memory as ACPI data.
Region of memory to be used, from ss to ss+nn.
memmap=nn[KMG]$ss[KMG]
[KNL,ACPI] Mark specific memory as reserved.
Region of memory to be used, from ss to ss+nn.
Example: Exclude memory from 0x18690000-0x1869ffff
memmap=64K$0x18690000
or
memmap=0x10000$0x18690000
memtest= [KNL,X86] Enable memtest
Format: <integer>
range: 0,4 : pattern number
default : 0 <disable>
meye.*= [HW] Set MotionEye Camera parameters
See Documentation/video4linux/meye.txt.
mfgpt_irq= [IA-32] Specify the IRQ to use for the
Multi-Function General Purpose Timers on AMD Geode
platforms.
mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
the BIOS has incorrectly applied a workaround. TinyBIOS
version 0.98 is known to be affected, 0.99 fixes the
problem by letting the user disable the workaround.
mga= [HW,DRM]
mminit_loglevel=
[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
parameter allows control of the logging verbosity for
the additional memory initialisation checks. A value
of 0 disables mminit logging and a level of 4 will
log everything. Information is printed at KERN_DEBUG
so loglevel=8 may also need to be specified.
mousedev.tap_time=
[MOUSE] Maximum time between finger touching and
leaving touchpad surface for touch to be considered
a tap and be reported as a left button click (for
touchpads working in absolute mode only).
Format: <msecs>
mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
reporting absolute coordinates, such as tablets
mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
reporting absolute coordinates, such as tablets
mpu401= [HW,OSS]
Format: <io>,<irq>
MTD_Partition= [MTD]
Format: <name>,<region-number>,<size>,<offset>
MTD_Region= [MTD] Format:
<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
mtdparts= [MTD]
See drivers/mtd/cmdlinepart.c.
mtdset= [ARM]
ARM/S3C2412 JIVE boot control
See arch/arm/mach-s3c2412/mach-jive.c
mtouchusb.raw_coordinates=
[HW] Make the MicroTouch USB driver use raw coordinates
('y', default) or cooked coordinates ('n')
n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
NCR_D700= [HW,SCSI]
See header of drivers/scsi/NCR_D700.c.
ncr5380= [HW,SCSI]
ncr53c400= [HW,SCSI]
ncr53c400a= [HW,SCSI]
ncr53c406a= [HW,SCSI]
ncr53c8xx= [HW,SCSI]
netdev= [NET] Network devices parameters
Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
Note that mem_start is often overloaded to mean
something different and driver-specific.
This usage is only documented in each driver source
file if at all.
nf_conntrack.acct=
[NETFILTER] Enable connection tracking flow accounting
0 to disable accounting
1 to enable accounting
Default value depends on CONFIG_NF_CT_ACCT that is
going to be removed in 2.6.29.
nfsaddrs= [NFS]
See Documentation/filesystems/nfsroot.txt.
nfsroot= [NFS] nfs root filesystem for disk-less boxes.
See Documentation/filesystems/nfsroot.txt.
nfs.callback_tcpport=
[NFS] set the TCP port on which the NFSv4 callback
channel should listen.
nfs.idmap_cache_timeout=
[NFS] set the maximum lifetime for idmapper cache
entries.
nfs.enable_ino64=
[NFS] enable 64-bit inode numbers.
If zero, the NFS client will fake up a 32-bit inode
number for the readdir() and stat() syscalls instead
of returning the full 64-bit number.
The default is to return 64-bit inode numbers.
nmi_debug= [KNL,AVR32] Specify one or more actions to take
when a NMI is triggered.
Format: [state][,regs][,debounce][,die]
nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
emulation library even if a 387 maths coprocessor
is present.
noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
caches in the slab allocator. Saves per-node memory,
but will impact performance.
noalign [KNL,ARM]
noapic [SMP,APIC] Tells the kernel to not make use of any
IOAPICs that may be present in the system.
nobats [PPC] Do not use BATs for mapping kernel lowmem
on "Classic" PPC cores.
nocache [ARM]
nodelayacct [KNL] Disable per-task delay accounting
nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
noefi [X86-32,X86-64] Disable EFI runtime services support.
noexec [IA-64]
noexec [X86-32,X86-64]
On X86-32 available only on PAE configured kernels.
noexec=on: enable non-executable mappings (default)
noexec=off: disable non-executable mappings
noexec32 [X86-64]
This affects only 32-bit executables.
noexec32=on: enable non-executable mappings (default)
read doesn't imply executable mappings
noexec32=off: disable non-executable mappings
read implies executable mappings
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]
no-hlt [BUGS=X86-32] Tells the kernel that the hlt
instruction doesn't work correctly and not to
use it.
nohalt [IA-64] Tells the kernel not to use the power saving
function PAL_HALT_LIGHT when idle. This increases
power-consumption. On the positive side, it reduces
interrupt wake-up latency, which may improve performance
in certain environments such as networked servers or
real-time systems.
nohz= [KNL] Boottime enable/disable dynamic ticks
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.
no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
broken timer IRQ sources.
noisapnp [ISAPNP] Disables ISA PnP code.
noinitrd [RAM] Tells the kernel not to load any configured
initial RAM disk.
nointroute [IA-64]
nojitter [IA64] Disables jitter checking for ITC timers.
nolapic [X86-32,APIC] Do not enable or use the local APIC.
nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
noltlbs [PPC] Do not use large page/tlb entries for kernel
lowmem mapping on PPC40x.
nomca [IA-64] Disable machine check abort handling
nomce [X86-32] Machine Check Exception
nomfgpt [X86-32] Disable Multi-Function General Purpose
Timer usage (for AMD Geode machines).
noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
noreplace-smp [X86-32,SMP] Don't replace SMP instructions
with UP alternatives
noresidual [PPC] Don't use residual data on PReP machines.
noresume [SWSUSP] Disables resume and restores original swap
space.
no-scroll [VGA] Disables scrollback.
This is required for the Braillex ib80-piezo Braille
reader made by F.H. Papenmeier (Germany).
nosbagart [IA-64]
nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
and disable the IO APIC. legacy for "maxcpus=0".
nosoftlockup [KNL] Disable the soft-lockup detector.
nosync [HW,M68K] Disables sync negotiation for all devices.
notsc [BUGS=X86-32] Disable Time Stamp Counter
nousb [USB] Disable the USB subsystem
nowb [ARM]
nptcg= [IA64] Override max number of concurrent global TLB
purges which is reported from either PAL_VM_SUMMARY or
SAL PALO.
numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
one of ['zone', 'node', 'default'] can be specified
This can be set from sysctl after boot.
See Documentation/sysctl/vm.txt for details.
nr_uarts= [SERIAL] maximum number of UARTs to be registered.
olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
Rather than timing out after 20 ms if an EC
command is not properly ACKed, override the length
of the timeout. We have interrupts disabled while
waiting for the ACK, so if this is set too high
interrupts *may* be lost!
opl3= [HW,OSS]
Format: <io>
oprofile.timer= [HW]
Use timer interrupt instead of performance counters
osst= [HW,SCSI] SCSI Tape Driver
Format: <buffer_size>,<write_threshold>
See also Documentation/scsi/st.txt.
panic= [KNL] Kernel behaviour on panic
Format: <timeout>
parkbd.port= [HW] Parallel port number the keyboard adapter is
connected to, default is 0.
Format: <parport#>
parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
0 for XT, 1 for AT (default is AT).
Format: <mode>
parport= [HW,PPT] Specify parallel ports. 0 disables.
Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
Use 'auto' to force the driver to use any
IRQ/DMA settings detected (the default is to
ignore detected IRQ/DMA settings because of
possible conflicts). You can specify the base
address, IRQ, and DMA settings; IRQ and DMA
should be numbers, or 'auto' (for using detected
settings on that particular port), or 'nofifo'
(to avoid using a FIFO even if it is detected).
Parallel ports are assigned in the order they
are specified on the command line, starting
with parport0.
parport_init_mode= [HW,PPT]
Configure VIA parallel port to operate in
a specific mode. This is necessary on Pegasos
computer where firmware has no options for setting
up parallel port mode and sets it to spp.
Currently this function knows 686a and 8231 chips.
Format: [spp|ps2|epp|ecp|ecpepp]
pas2= [HW,OSS] Format:
<io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
pas16= [HW,SCSI]
See header of drivers/scsi/pas16.c.
pause_on_oops=
Halt all CPUs after the first oops has been printed for
the specified number of seconds. This is to be used if
your oopses keep scrolling off the screen.
pcbit= [HW,ISDN]
pcd. [PARIDE]
See header of drivers/block/paride/pcd.c.
See also Documentation/paride.txt.
pci=option[,option...] [PCI] various PCI subsystem options:
off [X86-32] 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.
nobios [X86-32] disallow use of PCI BIOS, only direct
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
Mechanism 1.
conf2 [X86-32] 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
disable the use of PCIE advanced error reporting.
nodomains [PCI] Disable support for multiple PCI
root domains (aka PCI segments, in ACPI-speak).
nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Configuration
nomsi [MSI] If the PCI_MSI kernel config parameter is
enabled, this kernel boot option can be used to
disable the use of MSI interrupts system-wide.
biosirq [X86-32] Use PCI BIOS calls to get the interrupt
routing table. These calls are known to be buggy
on several machines and they hang the machine
when used, but on other computers it's the only
way to get the interrupt routing table. Try
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.
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
expansion ROMs that do not already have
BIOS assigned address ranges.
irqmask=0xMMMM [X86-32] 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
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
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
numbers ourselves, overriding
whatever the firmware may have done.
usepirqmask [X86-32] 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
or for PCI scanning.
use_crs [X86-32] Use _CRS for PCI resource
allocation.
routeirq Do IRQ routing for all PCI devices.
This is normally done in pci_enable_device(),
so this option is a temporary workaround
for broken drivers that don't call it.
skip_isa_align [X86] do not align io start addr, so can
handle more pci cards
firmware [ARM] Do not re-enumerate the bus but instead
just use the configuration from the
bootloader. This is currently used on
IXP2000 systems where the bus has to be
configured a certain way for adjunct CPUs.
noearly [X86] Don't do any early type 1 scanning.
This might help on some broken boards which
machine check when some devices' config space
is read. But various workarounds are disabled
and some IOMMU drivers will not work.
bfsort Sort PCI devices into breadth-first order.
This sorting is done to get a device
order compatible with older (<= 2.4) kernels.
nobfsort Don't sort PCI devices into breadth-first order.
cbiosize=nn[KMG] The fixed amount of bus space which is
reserved for the CardBus bridge's IO window.
The default value is 256 bytes.
cbmemsize=nn[KMG] The fixed amount of bus space which is
reserved for the CardBus bridge's memory
window. The default value is 64 megabytes.
pcmv= [HW,PCMCIA] BadgePAD 4
pd. [PARIDE]
See Documentation/paride.txt.
pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
boot time.
Format: { 0 | 1 }
See arch/parisc/kernel/pdc_chassis.c
pf. [PARIDE]
See Documentation/paride.txt.
pg. [PARIDE]
See Documentation/paride.txt.
pirq= [SMP,APIC] Manual mp-table setup
See Documentation/i386/IO-APIC.txt.
plip= [PPT,NET] Parallel port network link
Format: { parport<nr> | timid | 0 }
See also Documentation/parport.txt.
pmtmr= [X86] Manual setup of pmtmr I/O Port.
Override pmtimer IOPort with a hex value.
e.g. pmtmr=0x508
pnpacpi= [ACPI]
{ off }
pnpbios= [ISAPNP]
{ on | off | curr | res | no-curr | no-res }
pnp_reserve_irq=
[ISAPNP] Exclude IRQs for the autoconfiguration
pnp_reserve_dma=
[ISAPNP] Exclude DMAs for the autoconfiguration
pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Ranges are in pairs (I/O port base and size).
pnp_reserve_mem=
[ISAPNP] Exclude memory regions for the
autoconfiguration.
Ranges are in pairs (memory base and size).
print-fatal-signals=
[KNL] debug: print fatal signals
print-fatal-signals=1: print segfault info to
the kernel console.
default: off.
printk.time= Show timing data prefixed to each printk message line
Format: <bool> (1/Y/y=enable, 0/N/n=disable)
profile= [KNL] Enable kernel profiling via /proc/profile
Format: [schedule,]<number>
Param: "schedule" - profile schedule points.
Param: <number> - step/bucket size as a power of 2 for
statistical time based profiling.
Param: "sleep" - profile D-state sleeping (millisecs).
Requires CONFIG_SCHEDSTATS
Param: "kvm" - profile VM exits.
processor.max_cstate= [HW,ACPI]
Limit processor to maximum C-state
max_cstate=9 overrides any DMI blacklist limit.
processor.nocst [HW,ACPI]
Ignore the _CST method to determine C-states,
instead using the legacy FADT method
prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
before loading.
See Documentation/ramdisk.txt.
psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
probe for; one of (bare|imps|exps|lifebook|any).
psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
per second.
psmouse.resetafter= [HW,MOUSE]
Try to reset the device after so many bad packets
(0 = never).
psmouse.resolution=
[HW,MOUSE] Set desired mouse resolution, in dpi.
psmouse.smartscroll=
[HW,MOUSE] Controls Logitech smartscroll autorepeat.
0 = disabled, 1 = enabled (default).
pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Format:
<io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
pt. [PARIDE]
See Documentation/paride.txt.
pty.legacy_count=
[KNL] Number of legacy pty's. Overwrites compiled-in
default number.
quiet [KNL] Disable most log messages
r128= [HW,DRM]
raid= [HW,RAID]
See Documentation/md.txt.
ramdisk_blocksize= [RAM]
See Documentation/ramdisk.txt.
ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
See Documentation/ramdisk.txt.
rcupdate.blimit= [KNL,BOOT]
Set maximum number of finished RCU callbacks to process
in one batch.
rcupdate.qhimark= [KNL,BOOT]
Set threshold of queued
RCU callbacks over which batch limiting is disabled.
rcupdate.qlowmark= [KNL,BOOT]
Set threshold of queued RCU callbacks below which
batch limiting is re-enabled.
rdinit= [KNL]
Format: <full_path>
Run specified binary instead of /init from the ramdisk,
used for early userspace startup. See initrd.
reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Format: <reboot_mode>[,<reboot_mode2>[,...]]
See arch/*/kernel/reboot.c or arch/*/kernel/process.c
relax_domain_level=
[KNL, SMP] Set scheduler's default relax_domain_level.
See Documentation/cpusets.txt.
reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
reservetop= [X86-32]
Format: nn[KMG]
Reserves a hole at the top of the kernel virtual
address space.
reset_devices [KNL] Force drivers to reset the underlying device
during initialization.
resume= [SWSUSP]
Specify the partition device for software suspend
resume_offset= [SWSUSP]
Specify the offset from the beginning of the partition
given by "resume=" at which the swap header is located,
in <PAGE_SIZE> units (needed only for swap files).
See Documentation/power/swsusp-and-swap-files.txt
retain_initrd [RAM] Keep initrd memory after extraction
rhash_entries= [KNL,NET]
Set number of hash buckets for route cache
riscom8= [HW,SERIAL]
Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
ro [KNL] Mount root device read-only on boot
root= [KNL] Root filesystem
rootdelay= [KNL] Delay (in seconds) to pause before attempting to
mount the root filesystem
rootflags= [KNL] Set root filesystem mount option string
rootfstype= [KNL] Set root filesystem type
rootwait [KNL] Wait (indefinitely) for root device to show up.
Useful for devices that are detected asynchronously
(e.g. USB and MMC devices).
root_plug.vendor_id=
[ROOTPLUG] Override the default vendor ID
root_plug.product_id=
[ROOTPLUG] Override the default product ID
root_plug.debug=
[ROOTPLUG] Enable debugging output
rw [KNL] Mount root device read-write on boot
S [KNL] Run init in single mode
sa1100ir [NET]
See drivers/net/irda/sa1100_ir.c.
sbni= [NET] Granch SBNI12 leased line adapter
sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
Format: <io>[,<timeout>[,<isapnp>]]
scsi_debug_*= [SCSI]
See drivers/scsi/scsi_debug.c.
scsi_default_dev_flags=
[SCSI] SCSI default device flags
Format: <integer>
scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
Format: <vendor>:<model>:<flags>
(flags are integer value)
scsi_logging_level= [SCSI] a bit mask of logging levels
See drivers/scsi/scsi_logging.h for bits. Also
settable via sysctl at dev.scsi.logging_level
(/proc/sys/dev/scsi/logging_level).
There is also a nice 'scsi_logging_level' script in the
S390-tools package, available for download at
http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
discovered. async scans them in kernel threads,
allowing boot to proceed. none ignores them, expecting
user space to do the scan.
selinux [SELINUX] Disable or enable SELinux at boot time.
Format: { "0" | "1" }
See security/selinux/Kconfig help text.
0 -- disable.
1 -- enable.
Default value is set via kernel config option.
If enabled at boot time, /selinux/disable can be used
later to disable prior to initial policy load.
selinux_compat_net =
[SELINUX] Set initial selinux_compat_net flag value.
Format: { "0" | "1" }
0 -- use new secmark-based packet controls
1 -- use legacy packet controls
Default value is 0 (preferred).
Value can be changed at runtime via
/selinux/compat_net.
serialnumber [BUGS=X86-32]
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.
simeth= [IA-64]
simscsi=
slram= [HW,MTD]
slub_debug[=options[,slabs]] [MM, SLUB]
Enabling slub_debug allows one to determine the
culprit if slab objects become corrupted. Enabling
slub_debug can create guard zones around objects and
may poison objects when not in use. Also tracks the
last alloc / free. For more information see
Documentation/vm/slub.txt.
slub_max_order= [MM, SLUB]
Determines the maximum allowed order for slabs.
A high setting may cause OOMs due to memory
fragmentation. For more information see
Documentation/vm/slub.txt.
slub_min_objects= [MM, SLUB]
The minimum number of objects per slab. SLUB will
increase the slab order up to slub_max_order to
generate a sufficiently large slab able to contain
the number of objects indicated. The higher the number
of objects the smaller the overhead of tracking slabs
and the less frequently locks need to be acquired.
For more information see Documentation/vm/slub.txt.
slub_min_order= [MM, SLUB]
Determines the mininum page order for slabs. Must be
lower than slub_max_order.
For more information see Documentation/vm/slub.txt.
slub_nomerge [MM, SLUB]
Disable merging of slabs with similar size. May be
necessary if there is some reason to distinguish
allocs to different slabs. Debug options disable
merging on their own.
For more information see Documentation/vm/slub.txt.
smart2= [HW]
Format: <io1>[,<io2>[,...,<io8>]]
smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
attempt to substitute SMP alternatives once at boot.
smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
smsc-ircc2.ircc_sir= [HW] SIR base I/O port
smsc-ircc2.ircc_fir= [HW] FIR base I/O port
smsc-ircc2.ircc_irq= [HW] IRQ line
smsc-ircc2.ircc_dma= [HW] DMA channel
smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
0: Toshiba Satellite 1800 (GP data pin select)
1: Fast pin select (default)
2: ATC IRMode
snd-ad1816a= [HW,ALSA]
snd-ad1848= [HW,ALSA]
snd-ali5451= [HW,ALSA]
snd-als100= [HW,ALSA]
snd-als4000= [HW,ALSA]
snd-azt2320= [HW,ALSA]
snd-cmi8330= [HW,ALSA]
snd-cmipci= [HW,ALSA]
snd-cs4231= [HW,ALSA]
snd-cs4232= [HW,ALSA]
snd-cs4236= [HW,ALSA]
snd-cs4281= [HW,ALSA]
snd-cs46xx= [HW,ALSA]
snd-dt019x= [HW,ALSA]
snd-dummy= [HW,ALSA]
snd-emu10k1= [HW,ALSA]
snd-ens1370= [HW,ALSA]
snd-ens1371= [HW,ALSA]
snd-es968= [HW,ALSA]
snd-es1688= [HW,ALSA]
snd-es18xx= [HW,ALSA]
snd-es1938= [HW,ALSA]
snd-es1968= [HW,ALSA]
snd-fm801= [HW,ALSA]
snd-gusclassic= [HW,ALSA]
snd-gusextreme= [HW,ALSA]
snd-gusmax= [HW,ALSA]
snd-hdsp= [HW,ALSA]
snd-ice1712= [HW,ALSA]
snd-intel8x0= [HW,ALSA]
snd-interwave= [HW,ALSA]
snd-interwave-stb=
[HW,ALSA]
snd-korg1212= [HW,ALSA]
snd-maestro3= [HW,ALSA]
snd-mpu401= [HW,ALSA]
snd-mtpav= [HW,ALSA]
snd-nm256= [HW,ALSA]
snd-opl3sa2= [HW,ALSA]
snd-opti92x-ad1848=
[HW,ALSA]
snd-opti92x-cs4231=
[HW,ALSA]
snd-opti93x= [HW,ALSA]
snd-pmac= [HW,ALSA]
snd-rme32= [HW,ALSA]
snd-rme96= [HW,ALSA]
snd-rme9652= [HW,ALSA]
snd-sb8= [HW,ALSA]
snd-sb16= [HW,ALSA]
snd-sbawe= [HW,ALSA]
snd-serial= [HW,ALSA]
snd-sgalaxy= [HW,ALSA]
snd-sonicvibes= [HW,ALSA]
snd-sun-amd7930=
[HW,ALSA]
snd-sun-cs4231= [HW,ALSA]
snd-trident= [HW,ALSA]
snd-usb-audio= [HW,ALSA,USB]
snd-via82xx= [HW,ALSA]
snd-virmidi= [HW,ALSA]
snd-wavefront= [HW,ALSA]
snd-ymfpci= [HW,ALSA]
softlockup_panic=
[KNL] Should the soft-lockup detector generate panics.
sonypi.*= [HW] Sony Programmable I/O Control Device driver
See Documentation/sonypi.txt
specialix= [HW,SERIAL] Specialix multi-serial port adapter
See Documentation/specialix.txt.
spia_io_base= [HW,MTD]
spia_fio_base=
spia_pedr=
spia_peddr=
sscape= [HW,OSS]
Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
See Documentation/scsi/st.txt.
sti= [PARISC,HW]
Format: <num>
Set the STI (builtin display/keyboard on the HP-PARISC
machines) console (graphic card) which should be used
as the initial boot-console.
See also comment in drivers/video/console/sticore.c.
sti_font= [HW]
See comment in drivers/video/console/sticore.c.
stifb= [HW]
Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
sunrpc.pool_mode=
[NFS]
Control how the NFS server code allocates CPUs to
service thread pools. Depending on how many NICs
you have and where their interrupts are bound, this
option will affect which CPUs will do NFS serving.
Note: this parameter cannot be changed while the
NFS server is running.
auto the server chooses an appropriate mode
automatically using heuristics
global a single global pool contains all CPUs
percpu one pool for each CPU
pernode one pool for each NUMA node (equivalent
to global on non-NUMA machines)
swiotlb= [IA-64] Number of I/O TLB slabs
switches= [HW,M68k]
sym53c416= [HW,SCSI]
See header of drivers/scsi/sym53c416.c.
sysrq_always_enabled
[KNL]
Ignore sysrq setting - this boot parameter will
neutralize any effect of /proc/sys/kernel/sysrq.
Useful for debugging.
t128= [HW,SCSI]
See header of drivers/scsi/t128.c.
tdfx= [HW,DRM]
test_suspend= [SUSPEND]
Specify "mem" (for Suspend-to-RAM) or "standby" (for
standby suspend) as the system sleep state to briefly
enter during system startup. The system is woken from
this state using a wakeup-capable RTC alarm.
thash_entries= [KNL,NET]
Set number of hash buckets for TCP connection
thermal.act= [HW,ACPI]
-1: disable all active trip points in all thermal zones
<degrees C>: override all lowest active trip points
thermal.crt= [HW,ACPI]
-1: disable all critical trip points in all thermal zones
<degrees C>: lower all critical trip points
thermal.nocrt= [HW,ACPI]
Set to disable actions on ACPI thermal zone
critical and hot trip points.
thermal.off= [HW,ACPI]
1: disable ACPI thermal control
thermal.psv= [HW,ACPI]
-1: disable all passive trip points
<degrees C>: override all passive trip points to this value
thermal.tzp= [HW,ACPI]
Specify global default ACPI thermal zone polling rate
<deci-seconds>: poll all this frequency
0: no polling (default)
tmscsim= [HW,SCSI]
See comment before function dc390_setup() in
drivers/scsi/tmscsim.c.
tp720= [HW,PS2]
trix= [HW,OSS] MediaTrix AudioTrix Pro
Format:
<io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
turbografx.map[2|3]= [HW,JOY]
TurboGraFX parallel port interface
Format:
<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
See also Documentation/input/joystick-parport.txt
u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
See header of drivers/scsi/u14-34f.c.
uart401= [HW,OSS]
Format: <io>,<irq>
uart6850= [HW,OSS]
Format: <io>,<irq>
uhci-hcd.ignore_oc=
[USB] Ignore overcurrent events (default N).
Some badly-designed motherboards generate lots of
bogus events, for ports that aren't wired to
anything. Set this parameter to avoid log spamming.
Note that genuine overcurrent events won't be
reported either.
unknown_nmi_panic
[X86-32,X86-64]
Set unknown_nmi_panic=1 early on boot.
usbcore.autosuspend=
[USB] The autosuspend time delay (in seconds) used
for newly-detected USB devices (default 2). This
is the time required before an idle device will be
autosuspended. Devices for which the delay is set
to a negative value won't be autosuspended at all.
usbhid.mousepoll=
[USBHID] The interval which mice are to be polled at.
add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
kernel's map of available physical RAM.
vdso= [X86-32,SH,x86-64]
vdso=2: enable compat VDSO (default with COMPAT_VDSO)
vdso=1: enable VDSO (default)
vdso=0: disable VDSO mapping
vdso32= [X86-32,X86-64]
vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
vdso32=1: enable 32-bit VDSO (default)
vdso32=0: disable 32-bit VDSO mapping
vector= [IA-64,SMP]
vector=percpu: enable percpu vector domain
video= [FB] Frame buffer configuration
See Documentation/fb/modedb.txt.
vga= [BOOT,X86-32] Select a particular video mode
See Documentation/i386/boot.txt and
Documentation/svga.txt.
Use vga=ask for menu.
This is actually a boot loader parameter; the value is
passed to the kernel using a special protocol.
vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
size of <nn>. This can be used to increase the
minimum size (128MB on x86). It can also be used to
decrease the size and leave more room for directly
mapped kernel RAM.
vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
Format: <command>
vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
Format: <command>
vmpoff= [KNL,S390] Perform z/VM CP command after power off.
Format: <command>
waveartist= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>
wd33c93= [HW,SCSI]
See header of drivers/scsi/wd33c93.c.
wd7000= [HW,SCSI]
See header of drivers/scsi/wd7000.c.
wdt= [WDT] Watchdog
See Documentation/watchdog/wdt.txt.
xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
xd_geo= See header of drivers/block/xd.c.
xirc2ps_cs= [NET,PCMCIA]
Format:
<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
norandmaps Don't use address space randomization
Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
______________________________________________________________________
TODO:
Add documentation for ALSA options.
Add more DRM drivers.
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