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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
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3
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
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20This document may not be entirely up to date and comprehensive. The command
21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22module. Loadable modules, after being loaded into the running kernel, also
23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24parameters may be changed at runtime by the command
25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
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27The parameters listed below are only valid if certain kernel build options were
28enabled and if respective hardware is present. The text in square brackets at
29the beginning of each description states the restrictions within which a
30parameter is applicable:
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31
32 ACPI ACPI support is enabled.
c99c108a 33 AGP AGP (Accelerated Graphics Port) is enabled.
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34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AX25 Appropriate AX.25 support is enabled.
0ae53640 38 BLACKFIN Blackfin architecture is enabled.
a9913044 39 DRM Direct Rendering Management support is enabled.
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40 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
41 EFI EFI Partitioning (GPT) is enabled
42 EIDE EIDE/ATAPI support is enabled.
43 FB The frame buffer device is enabled.
44 HW Appropriate hardware is enabled.
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45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
11ef697b 51 LIBATA Libata driver is enabled
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52 LP Printer support is enabled.
53 LOOP Loopback device support is enabled.
54 M68k M68k architecture is enabled.
55 These options have more detailed description inside of
56 Documentation/m68k/kernel-options.txt.
57 MCA MCA bus support is enabled.
58 MDA MDA console support is enabled.
59 MOUSE Appropriate mouse support is enabled.
309e57df 60 MSI Message Signaled Interrupts (PCI).
c8facbb6 61 MTD MTD (Memory Technology Device) support is enabled.
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62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
734efb46 64 GENERIC_TIME The generic timeofday code is enabled.
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65 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
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67 PV_OPS A paravirtualized kernel is enabled.
68 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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69 PARISC The PA-RISC architecture is enabled.
70 PCI PCI bus support is enabled.
71 PCMCIA The PCMCIA subsystem is enabled.
72 PNP Plug & Play support is enabled.
73 PPC PowerPC architecture is enabled.
74 PPT Parallel port support is enabled.
75 PS2 Appropriate PS/2 support is enabled.
76 RAM RAM disk support is enabled.
77 S390 S390 architecture is enabled.
78 SCSI Appropriate SCSI support is enabled.
79 A lot of drivers has their options described inside of
80 Documentation/scsi/.
81 SELINUX SELinux support is enabled.
82 SERIAL Serial support is enabled.
e523d93c 83 SH SuperH architecture is enabled.
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84 SMP The kernel is an SMP kernel.
85 SPARC Sparc architecture is enabled.
a9913044 86 SWSUSP Software suspend is enabled.
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87 TS Appropriate touchscreen support is enabled.
88 USB USB support is enabled.
89 USBHID USB Human Interface Device support is enabled.
90 V4L Video For Linux support is enabled.
91 VGA The VGA console has been enabled.
92 VT Virtual terminal support is enabled.
93 WDT Watchdog support is enabled.
94 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 95 X86-32 X86-32, aka i386 architecture is enabled.
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96 X86-64 X86-64 architecture is enabled.
97 More X86-64 boot options can be found in
98 Documentation/x86_64/boot-options.txt .
99
100In addition, the following text indicates that the option:
101
102 BUGS= Relates to possible processor bugs on the said processor.
103 KNL Is a kernel start-up parameter.
104 BOOT Is a boot loader parameter.
105
106Parameters denoted with BOOT are actually interpreted by the boot
107loader, and have no meaning to the kernel directly.
108Do not modify the syntax of boot loader parameters without extreme
109need or coordination with <Documentation/i386/boot.txt>.
110
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111There are also arch-specific kernel-parameters not documented here.
112See for example <Documentation/x86_64/boot-options.txt>.
113
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114Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
115a trailing = on the name of any parameter states that that parameter will
116be entered as an environment variable, whereas its absence indicates that
117it will appear as a kernel argument readable via /proc/cmdline by programs
118running once the system is up.
119
9c4751fd 120The number of kernel parameters is not limited, but the length of the
121complete command line (parameters including spaces etc.) is limited to
122a fixed number of characters. This limit depends on the architecture
123and is between 256 and 4096 characters. It is defined in the file
124./include/asm/setup.h as COMMAND_LINE_SIZE.
125
126
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127 acpi= [HW,ACPI,X86-64,i386]
128 Advanced Configuration and Power Interface
a9913044 129 Format: { force | off | ht | strict | noirq }
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130 force -- enable ACPI if default was off
131 off -- disable ACPI if default was on
132 noirq -- do not use ACPI for IRQ routing
133 ht -- run only enough ACPI to enable Hyper Threading
a9913044 134 strict -- Be less tolerant of platforms that are not
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135 strictly ACPI specification compliant.
136
137 See also Documentation/pm.txt, pci=noacpi
138
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139 acpi_apic_instance= [ACPI, IOAPIC]
140 Format: <int>
141 2: use 2nd APIC table, if available
142 1,0: use 1st APIC table
4e381a4f 143 default: 0
a1fdcc0d 144
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145 acpi_sleep= [HW,ACPI] Sleep options
146 Format: { s3_bios, s3_mode }
147 See Documentation/power/video.txt
a9913044 148
1da177e4 149 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 150 Format: { level | edge | high | low }
1da177e4 151
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152 acpi_irq_balance [HW,ACPI]
153 ACPI will balance active IRQs
154 default in APIC mode
1da177e4 155
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156 acpi_irq_nobalance [HW,ACPI]
157 ACPI will not move active IRQs (default)
158 default in PIC mode
1da177e4 159
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160 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
161 use by PCI
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162 Format: <irq>,<irq>...
163
a9913044 164 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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165 Format: <irq>,<irq>...
166
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167 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
168
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169 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
170 Format: To spoof as Windows 98: ="Microsoft Windows"
171
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172 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
173 acpi_osi="string1" # add string1 -- only one string
174 acpi_osi="!string2" # remove built-in string2
175 acpi_osi= # disable all strings
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176
177 acpi_serialize [HW,ACPI] force serialization of AML methods
178
179 acpi_skip_timer_override [HW,ACPI]
180 Recognize and ignore IRQ0/pin2 Interrupt Override.
181 For broken nForce2 BIOS resulting in XT-PIC timer.
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182 acpi_use_timer_override [HW,ACPI}
183 Use timer override. For some broken Nvidia NF5 boards
184 that require a timer override, but don't have
185 HPET
1da177e4 186
f989106c 187 acpi.debug_layer= [HW,ACPI]
1da177e4 188 Format: <int>
a9913044 189 Each bit of the <int> indicates an ACPI debug layer,
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190 1: enable, 0: disable. It is useful for boot time
191 debugging. After system has booted up, it can be set
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192 via /sys/module/acpi/parameters/debug_layer.
193 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
194 Available bits (add the numbers together) to enable debug output
195 for specific parts of the ACPI subsystem:
196 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
197 0x10 namespace 0x20 parser 0x40 dispatcher
198 0x80 executer 0x100 resources 0x200 acpica debugger
199 0x400 os services 0x800 acpica disassembler.
200 The number can be in decimal or prefixed with 0x in hex.
201 Warning: Many of these options can produce a lot of
202 output and make your system unusable. Be very careful.
203
204 acpi.debug_level= [HW,ACPI]
1da177e4 205 Format: <int>
a9913044 206 Each bit of the <int> indicates an ACPI debug level,
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207 1: enable, 0: disable. It is useful for boot time
208 debugging. After system has booted up, it can be set
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209 via /sys/module/acpi/parameters/debug_level.
210 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
211 Available bits (add the numbers together) to enable different
212 debug output levels of the ACPI subsystem:
213 0x01 error 0x02 warn 0x04 init 0x08 debug object
214 0x10 info 0x20 init names 0x40 parse 0x80 load
215 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
216 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
217 0x10000 resources 0x20000 user requests 0x40000 package.
218 The number can be in decimal or prefixed with 0x in hex.
219 Warning: Many of these options can produce a lot of
220 output and make your system unusable. Be very careful.
221
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222
223 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
224
cd4f0ef7 225 acpi_pm_good [X86-32,X86-64]
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226 Override the pmtimer bug detection: force the kernel
227 to assume that this machine's pmtimer latches its value
228 and always returns good values.
229
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230 agp= [AGP]
231 { off | try_unsupported }
232 off: disable AGP support
233 try_unsupported: try to drive unsupported chipsets
234 (may crash computer or cause data corruption)
235
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236 enable_timer_pin_1 [i386,x86-64]
237 Enable PIN 1 of APIC timer
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238 Can be useful to work around chipset bugs
239 (in particular on some ATI chipsets).
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240 The kernel tries to set a reasonable default.
241
242 disable_timer_pin_1 [i386,x86-64]
243 Disable PIN 1 of APIC timer
244 Can be useful to work around chipset bugs.
245
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246 ad1848= [HW,OSS]
247 Format: <io>,<irq>,<dma>,<dma2>,<type>
248
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249 advansys= [HW,SCSI]
250 See header of drivers/scsi/advansys.c.
251
252 advwdt= [HW,WDT] Advantech WDT
253 Format: <iostart>,<iostop>
254
255 aedsp16= [HW,OSS] Audio Excel DSP 16
256 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
257 See also header of sound/oss/aedsp16.c.
a9913044 258
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259 aha152x= [HW,SCSI]
260 See Documentation/scsi/aha152x.txt.
261
262 aha1542= [HW,SCSI]
263 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
264
265 aic7xxx= [HW,SCSI]
266 See Documentation/scsi/aic7xxx.txt.
267
268 aic79xx= [HW,SCSI]
269 See Documentation/scsi/aic79xx.txt.
270
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271 amijoy.map= [HW,JOY] Amiga joystick support
272 Map of devices attached to JOY0DAT and JOY1DAT
273 Format: <a>,<b>
274 See also Documentation/kernel/input/joystick.txt
275
276 analog.map= [HW,JOY] Analog joystick and gamepad support
277 Specifies type or capabilities of an analog joystick
278 connected to one of 16 gameports
279 Format: <type1>,<type2>,..<type16>
280
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281 apc= [HW,SPARC]
282 Power management functions (SPARCstation-4/5 + deriv.)
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283 Format: noidle
284 Disable APC CPU standby support. SPARCstation-Fox does
285 not play well with APC CPU idle - disable it if you have
286 APC and your system crashes randomly.
287
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288 apic= [APIC,i386] Advanced Programmable Interrupt Controller
289 Change the output verbosity whilst booting
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290 Format: { quiet (default) | verbose | debug }
291 Change the amount of debugging information output
292 when initialising the APIC and IO-APIC components.
a9913044 293
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294 apm= [APM] Advanced Power Management
295 See header of arch/i386/kernel/apm.c.
296
297 applicom= [HW]
298 Format: <mem>,<irq>
a9913044 299
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300 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
301 Format: <io>,<irq>,<nodeID>
302
303 ataflop= [HW,M68k]
304
305 atarimouse= [HW,MOUSE] Atari Mouse
306
307 atascsi= [HW,SCSI] Atari SCSI
308
309 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
310 EzKey and similar keyboards
311
312 atkbd.reset= [HW] Reset keyboard during initialization
313
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314 atkbd.set= [HW] Select keyboard code set
315 Format: <int> (2 = AT (default), 3 = PS/2)
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316
317 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
318 keyboards
319
320 atkbd.softraw= [HW] Choose between synthetic and real raw mode
321 Format: <bool> (0 = real, 1 = synthetic (default))
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322
323 atkbd.softrepeat= [HW]
324 Use software keyboard repeat
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325
326 autotest [IA64]
327
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328 baycom_epp= [HW,AX25]
329 Format: <io>,<mode>
a9913044 330
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331 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
332 Format: <io>,<mode>
333 See header of drivers/net/hamradio/baycom_par.c.
334
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335 baycom_ser_fdx= [HW,AX25]
336 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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337 Format: <io>,<irq>,<mode>[,<baud>]
338 See header of drivers/net/hamradio/baycom_ser_fdx.c.
339
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340 baycom_ser_hdx= [HW,AX25]
341 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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342 Format: <io>,<irq>,<mode>
343 See header of drivers/net/hamradio/baycom_ser_hdx.c.
344
345 blkmtd_device= [HW,MTD]
346 blkmtd_erasesz=
347 blkmtd_ro=
348 blkmtd_bs=
349 blkmtd_count=
350
351 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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352 bttv.radio= Most important insmod options are available as
353 kernel args too.
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354 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
355 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
356
357 BusLogic= [HW,SCSI]
358 See drivers/scsi/BusLogic.c, comment before function
359 BusLogic_ParseDriverOptions().
360
361 c101= [NET] Moxa C101 synchronous serial card
362
cd4f0ef7 363 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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364 Sometimes CPU hardware bugs make them report the cache
365 size incorrectly. The kernel will attempt work arounds
366 to fix known problems, but for some CPUs it is not
367 possible to determine what the correct size should be.
368 This option provides an override for these situations.
369
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370 chandev= [HW,NET] Generic channel device initialisation
371
372 checkreqprot [SELINUX] Set initial checkreqprot flag value.
373 Format: { "0" | "1" }
374 See security/selinux/Kconfig help text.
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375 0 -- check protection applied by kernel (includes
376 any implied execute protection).
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377 1 -- check protection requested by application.
378 Default value is set via a kernel config option.
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379 Value can be changed at runtime via
380 /selinux/checkreqprot.
381
cd4f0ef7 382 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 383 [Deprecated]
3f6dee9b 384 Forces specified clocksource (if available) to be used
734efb46 385 when calculating gettimeofday(). If specified
3f6dee9b 386 clocksource is not available, it defaults to PIT.
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387 Format: { pit | tsc | cyclone | pmtmr }
388
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389 clocksource= [GENERIC_TIME] Override the default clocksource
390 Format: <string>
391 Override the default clocksource and use the clocksource
392 with the name specified.
393 Some clocksource names to choose from, depending on
394 the platform:
395 [all] jiffies (this is the base, fallback clocksource)
396 [ACPI] acpi_pm
397 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
398 pxa_timer,timer3,32k_counter,timer0_1
399 [AVR32] avr32
cd4f0ef7 400 [X86-32] pit,hpet,tsc,vmi-timer;
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401 scx200_hrt on Geode; cyclone on IBM x440
402 [MIPS] MIPS
403 [PARISC] cr16
404 [S390] tod
405 [SH] SuperH
406 [SPARC64] tick
407 [X86-64] hpet,tsc
408
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409 code_bytes [IA32] How many bytes of object code to print in an
410 oops report.
411 Range: 0 - 8192
412 Default: 64
413
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414 disable_8254_timer
415 enable_8254_timer
416 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
417 over the 8254 in addition to over the IO-APIC. The
418 kernel tries to set a sensible default.
419
cd4f0ef7 420 hpet= [X86-32,HPET] option to disable HPET and use PIT.
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421 Format: disable
422
1da177e4 423 com20020= [HW,NET] ARCnet - COM20020 chipset
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424 Format:
425 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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426
427 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
428 Format: <io>[,<irq>]
429
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430 com90xx= [HW,NET]
431 ARCnet - COM90xx chipset (memory-mapped buffers)
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432 Format: <io>[,<irq>[,<memstart>]]
433
434 condev= [HW,S390] console device
435 conmode=
a9913044 436
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437 console= [KNL] Output console device and options.
438
439 tty<n> Use the virtual console device <n>.
440
441 ttyS<n>[,options]
f1a1c2dc 442 ttyUSB0[,options]
1da177e4 443 Use the specified serial port. The options are of
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RD
444 the form "bbbbpnf", where "bbbb" is the baud rate,
445 "p" is parity ("n", "o", or "e"), "n" is number of
446 bits, and "f" is flow control ("r" for RTS or
447 omit it). Default is "9600n8".
448
449 See Documentation/serial-console.txt for more
450 information. See
451 Documentation/networking/netconsole.txt for an
452 alternative.
1da177e4 453
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454 uart[8250],io,<addr>[,options]
455 uart[8250],mmio,<addr>[,options]
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LT
456 Start an early, polled-mode console on the 8250/16550
457 UART at the specified I/O port or MMIO address,
458 switching to the matching ttyS device later. The
459 options are the same as for ttyS, above.
460
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461 earlycon= [KNL] Output early console device and options.
462 uart[8250],io,<addr>[,options]
463 uart[8250],mmio,<addr>[,options]
464 Start an early, polled-mode console on the 8250/16550
465 UART at the specified I/O port or MMIO address.
466 The options are the same as for ttyS, above.
467
1da177e4 468 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
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469 Format:
470 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 471
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472 crashkernel=nn[KMG]@ss[KMG]
473 [KNL] Reserve a chunk of physical memory to
474 hold a kernel to switch to with kexec on panic.
475
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476 cs4232= [HW,OSS]
477 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
478
479 cs89x0_dma= [HW,NET]
480 Format: <dma>
481
482 cs89x0_media= [HW,NET]
483 Format: { rj45 | aui | bnc }
a9913044 484
1da177e4 485 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
a9913044
RD
486
487 dasd= [HW,NET]
1da177e4
LT
488 See header of drivers/s390/block/dasd_devmap.c.
489
490 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
491 (one device per port)
492 Format: <port#>,<type>
493 See also Documentation/input/joystick-parport.txt
494
495 debug [KNL] Enable kernel debugging (events log level).
496
cae2ed9a
IM
497 debug_locks_verbose=
498 [KNL] verbose self-tests
499 Format=<0|1>
500 Print debugging info while doing the locking API
501 self-tests.
502 We default to 0 (no extra messages), setting it to
503 1 will print _a lot_ more information - normally
504 only useful to kernel developers.
505
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LT
506 decnet= [HW,NET]
507 Format: <area>[,<node>]
508 See also Documentation/networking/decnet.txt.
509
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510 default_blu= [VT]
511 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
512 Change the default blue palette of the console.
513 This is a 16-member array composed of values
514 ranging from 0-255.
515
516 default_grn= [VT]
517 Format: <green0>,<green1>,<green2>,...,<green15>
518 Change the default green palette of the console.
519 This is a 16-member array composed of values
520 ranging from 0-255.
521
522 default_red= [VT]
523 Format: <red0>,<red1>,<red2>,...,<red15>
524 Change the default red palette of the console.
525 This is a 16-member array composed of values
526 ranging from 0-255.
527
528 default_utf8= [VT]
529 Format=<0|1>
530 Set system-wide default UTF-8 mode for all tty's.
531 Default is 0 and by setting to 1, it enables UTF-8
532 mode for all newly opened or allocated terminals.
533
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LT
534 dhash_entries= [KNL]
535 Set number of hash buckets for dentry cache.
a9913044 536
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LT
537 digi= [HW,SERIAL]
538 IO parameters + enable/disable command.
539
540 digiepca= [HW,SERIAL]
541 See drivers/char/README.epca and
542 Documentation/digiepca.txt.
543
544 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
545 support available.
546 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
547
548 dmasound= [HW,OSS] Sound subsystem buffers
549
550 dscc4.setup= [NET]
551
552 dtc3181e= [HW,SCSI]
553
0ae53640 554 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
1da177e4
LT
555 earlyprintk=vga
556 earlyprintk=serial[,ttySn[,baudrate]]
557
a9913044 558 Append ",keep" to not disable it when the real console
1da177e4
LT
559 takes over.
560
561 Only vga or serial at a time, not both.
562
563 Currently only ttyS0 and ttyS1 are supported.
564
565 Interaction with the standard serial driver is not
566 very good.
567
568 The VGA output is eventually overwritten by the real
569 console.
570
571 eata= [HW,SCSI]
572
53f11d4f
LB
573 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
574 Format: <int>
575 0: polling mode
576 non-0: interrupt mode (default)
577
1da177e4
LT
578 eda= [HW,PS2]
579
580 edb= [HW,PS2]
581
582 edd= [EDD]
583 Format: {"of[f]" | "sk[ipmbr]"}
584 See comment in arch/i386/boot/edd.S
585
a9913044 586 eicon= [HW,ISDN]
1da177e4
LT
587 Format: <id>,<membase>,<irq>
588
589 eisa_irq_edge= [PARISC,HW]
590 See header of drivers/parisc/eisa.c.
591
cd4f0ef7 592 elanfreq= [X86-32]
1da177e4
LT
593 See comment before function elanfreq_setup() in
594 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
595
596 elevator= [IOSCHED]
16ab3adf 597 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
598 See Documentation/block/as-iosched.txt and
599 Documentation/block/deadline-iosched.txt for details.
600
cd4f0ef7 601 elfcorehdr= [X86-32, X86_64]
a9913044 602 Specifies physical address of start of kernel core
aac04b32
VG
603 image elf header. Generally kexec loader will
604 pass this option to capture kernel.
605 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
606
607 enforcing [SELINUX] Set initial enforcing status.
608 Format: {"0" | "1"}
609 See security/selinux/Kconfig help text.
610 0 -- permissive (log only, no denials).
611 1 -- enforcing (deny and log).
612 Default value is 0.
613 Value can be changed at runtime via /selinux/enforce.
614
1da177e4
LT
615 es1371= [HW,OSS]
616 Format: <spdif>,[<nomix>,[<amplifier>]]
617 See also header of sound/oss/es1371.c.
a9913044 618
1da177e4
LT
619 ether= [HW,NET] Ethernet cards parameters
620 This option is obsoleted by the "netdev=" option, which
621 has equivalent usage. See its documentation for details.
622
623 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
624 Format: <io>[,<irq>]
625
de1ba09b
AM
626 failslab=
627 fail_page_alloc=
628 fail_make_request=[KNL]
629 General fault injection mechanism.
630 Format: <interval>,<probability>,<space>,<times>
631 See also /Documentation/fault-injection/.
632
1da177e4
LT
633 fd_mcs= [HW,SCSI]
634 See header of drivers/scsi/fd_mcs.c.
635
636 fdomain= [HW,SCSI]
637 See header of drivers/scsi/fdomain.c.
638
639 floppy= [HW]
640 See Documentation/floppy.txt.
641
1da177e4
LT
642 gamecon.map[2|3]=
643 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
644 support via parallel port (up to 5 devices per port)
645 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
646 See also Documentation/input/joystick-parport.txt
647
648 gamma= [HW,DRM]
649
650 gdth= [HW,SCSI]
651 See header of drivers/scsi/gdth.c.
652
653 gpt [EFI] Forces disk with valid GPT signature but
654 invalid Protective MBR to be treated as GPT.
655
1da177e4
LT
656 gvp11= [HW,SCSI]
657
658 hashdist= [KNL,NUMA] Large hashes allocated during boot
659 are distributed across NUMA nodes. Defaults on
660 for IA-64, off otherwise.
a9913044 661 Format: 0 | 1 (for off | on)
1da177e4
LT
662
663 hcl= [IA-64] SGI's Hardware Graph compatibility layer
664
665 hd= [EIDE] (E)IDE hard drive subsystem geometry
666 Format: <cyl>,<head>,<sect>
667
668 hd?= [HW] (E)IDE subsystem
669 hd?lun= See Documentation/ide.txt.
670
671 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
672 size of <nn>. This works even on boxes that have no
673 highmem otherwise. This also works to reduce highmem
674 size on bigger boxes.
675
54cdfdb4
TG
676 highres= [KNL] Enable/disable high resolution timer mode.
677 Valid parameters: "on", "off"
678 Default: "on"
679
1da177e4
LT
680 hisax= [HW,ISDN]
681 See Documentation/isdn/README.HiSax.
682
cd4f0ef7 683 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
1da177e4 684
1da177e4 685 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
686 i8042.dumbkbd [HW] Pretend that controller can only read data from
687 keyboard and cannot control its state
1da177e4
LT
688 (Don't attempt to blink the leds)
689 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 690 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
691 i8042.nomux [HW] Don't check presence of an active multiplexing
692 controller
693 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
694 controllers
695 i8042.panicblink=
696 [HW] Frequency with which keyboard LEDs should blink
697 when kernel panics (default is 0.5 sec)
698 i8042.reset [HW] Reset the controller during init and cleanup
699 i8042.unlock [HW] Unlock (ignore) the keylock
700
701 i810= [HW,DRM]
702
e70c9d5e
DT
703 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
704 indicates that the driver is running on unsupported
705 hardware.
1da177e4
LT
706 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
707 does not match list of supported models.
708 i8k.power_status
709 [HW] Report power status in /proc/i8k
710 (disabled by default)
711 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
712 capability is set.
713
714 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
715 See Documentation/mca.txt.
716
717 icn= [HW,ISDN]
718 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
719
720 ide= [HW] (E)IDE subsystem
721 Format: ide=nodma or ide=doubler or ide=reverse
722 See Documentation/ide.txt.
723
724 ide?= [HW] (E)IDE subsystem
725 Format: ide?=noprobe or chipset specific parameters.
726 See Documentation/ide.txt.
a9913044 727
1da177e4
LT
728 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
729 See Documentation/ide.txt.
730
f039b754
AK
731 idle= [X86]
732 Format: idle=poll or idle=mwait
733 Poll forces a polling idle loop that can slightly improves the performance
734 of waking up a idle CPU, but will use a lot of power and make the system
735 run hot. Not recommended.
736 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
737 to not use it because it doesn't save as much power as a normal idle
738 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
739 as idle=poll.
a9913044 740
79290822
IM
741 ignore_loglevel [KNL]
742 Ignore loglevel setting - this will print /all/
743 kernel messages to the console. Useful for debugging.
744
1da177e4
LT
745 ihash_entries= [KNL]
746 Set number of hash buckets for inode cache.
747
748 in2000= [HW,SCSI]
749 See header of drivers/scsi/in2000.c.
750
751 init= [KNL]
752 Format: <full_path>
753 Run specified binary instead of /sbin/init as init
754 process.
755
756 initcall_debug [KNL] Trace initcalls as they are executed. Useful
757 for working out where the kernel is dying during
758 startup.
759
760 initrd= [BOOT] Specify the location of the initial ramdisk
761
762 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
763 Format: <irq>
764
765 inttest= [IA64]
766
767 io7= [HW] IO7 for Marvel based alpha systems
768 See comment before marvel_specify_io7 in
769 arch/alpha/kernel/core_marvel.c.
770
771 ip= [IP_PNP]
772 See Documentation/nfsroot.txt.
773
774 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
775 See comment before ip2_setup() in
776 drivers/char/ip2/ip2base.c.
1da177e4
LT
777
778 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
779 See header of drivers/scsi/ips.c.
780
72c4a13a
SH
781 ports= [IP_VS_FTP] IPVS ftp helper module
782 Default is 21.
783 Up to 8 (IP_VS_APP_MAX_PORTS) ports
784 may be specified.
785 Format: <port>,<port>....
786
200803df
AC
787 irqfixup [HW]
788 When an interrupt is not handled search all handlers
789 for it. Intended to get systems with badly broken
790 firmware running.
791
792 irqpoll [HW]
793 When an interrupt is not handled search all handlers
794 for it. Also check all handlers each timer
795 interrupt. Intended to get systems with badly broken
796 firmware running.
797
1da177e4 798 isapnp= [ISAPNP]
a9913044 799 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
800
801 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
802 Format:
803 <cpu number>,...,<cpu number>
804 or
805 <cpu number>-<cpu number> (must be a positive range in ascending order)
806 or a mixture
807 <cpu number>,...,<cpu number>-<cpu number>
1da177e4
LT
808 This option can be used to specify one or more CPUs
809 to isolate from the general SMP balancing and scheduling
810 algorithms. The only way to move a process onto or off
811 an "isolated" CPU is via the CPU affinity syscalls.
812 <cpu number> begins at 0 and the maximum value is
813 "number of CPUs in system - 1".
814
815 This option is the preferred way to isolate CPUs. The
a9913044
RD
816 alternative -- manually setting the CPU mask of all
817 tasks in the system -- can cause problems and
818 suboptimal load balancer performance.
1da177e4 819
a9913044 820 iucv= [HW,NET]
1da177e4
LT
821
822 js= [HW,JOY] Analog joystick
823 See Documentation/input/joystick.txt.
824
cd4f0ef7 825 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
ed7ed365
MG
826 specifies the amount of memory usable by the kernel
827 for non-movable allocations. The requested amount is
828 spread evenly throughout all nodes in the system. The
829 remaining memory in each node is used for Movable
830 pages. In the event, a node is too small to have both
831 kernelcore and Movable pages, kernelcore pages will
832 take priority and other nodes will have a larger number
833 of kernelcore pages. The Movable zone is used for the
834 allocation of pages that may be reclaimed or moved
835 by the page migration subsystem. This means that
836 HugeTLB pages may not be allocated from this zone.
837 Note that allocations like PTEs-from-HighMem still
838 use the HighMem zone if it exists, and the Normal
839 zone if it does not.
840
cd4f0ef7 841 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
7e63efef
MG
842 is similar to kernelcore except it specifies the
843 amount of memory used for migratable allocations.
844 If both kernelcore and movablecore is specified,
845 then kernelcore will be at *least* the specified
846 value but may be more. If movablecore on its own
847 is specified, the administrator must be careful
848 that the amount of memory usable for all allocations
849 is not too small.
850
1da177e4
LT
851 keepinitrd [HW,ARM]
852
cd4f0ef7 853 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1da177e4
LT
854 in oops dumps.
855
856 l2cr= [PPC]
857
cd4f0ef7 858 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 859 disabled it.
1da177e4 860
cd4f0ef7 861 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
e585bef8
TG
862 C2 power state.
863
1da177e4
LT
864 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
865 Format: addr:<io>,irq:<irq>
866
1da177e4
LT
867 load_ramdisk= [RAM] List of ramdisks to load from floppy
868 See Documentation/ramdisk.txt.
869
a6b25b67
RD
870 lockd.nlm_grace_period=P [NFS] Assign grace period.
871 Format: <integer>
1da177e4 872
a6b25b67
RD
873 lockd.nlm_tcpport=N [NFS] Assign TCP port.
874 Format: <integer>
875
876 lockd.nlm_timeout=T [NFS] Assign timeout value.
877 Format: <integer>
878
879 lockd.nlm_udpport=M [NFS] Assign UDP port.
880 Format: <integer>
1da177e4
LT
881
882 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
883 Format: <irq>
884
885 loglevel= All Kernel Messages with a loglevel smaller than the
886 console loglevel will be printed to the console. It can
887 also be changed with klogd or other programs. The
888 loglevels are defined as follows:
889
890 0 (KERN_EMERG) system is unusable
891 1 (KERN_ALERT) action must be taken immediately
892 2 (KERN_CRIT) critical conditions
893 3 (KERN_ERR) error conditions
894 4 (KERN_WARNING) warning conditions
895 5 (KERN_NOTICE) normal but significant condition
896 6 (KERN_INFO) informational
897 7 (KERN_DEBUG) debug-level messages
898
899 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
900 Format: { n | nk | nM }
901 n must be a power of two. The default size
902 is set in the kernel config file.
1da177e4
LT
903
904 lp=0 [LP] Specify parallel ports to use, e.g,
905 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
906 lp=reset first parallel port). 'lp=0' disables the
907 lp=auto printer driver. 'lp=reset' (which can be
908 specified in addition to the ports) causes
909 attached printers to be reset. Using
910 lp=port1,port2,... specifies the parallel ports
911 to associate lp devices with, starting with
912 lp0. A port specification may be 'none' to skip
913 that lp device, or a parport name such as
914 'parport0'. Specifying 'lp=auto' instead of a
915 port specification list means that device IDs
916 from each port should be examined, to see if
917 an IEEE 1284-compliant printer is attached; if
918 so, the driver will manage that printer.
919 See also header of drivers/char/lp.c.
920
921 lpj=n [KNL]
922 Sets loops_per_jiffy to given constant, thus avoiding
923 time-consuming boot-time autodetection (up to 250 ms per
924 CPU). 0 enables autodetection (default). To determine
925 the correct value for your kernel, boot with normal
926 autodetection and see what value is printed. Note that
927 on SMP systems the preset will be applied to all CPUs,
928 which is likely to cause problems if your CPUs need
929 significantly divergent settings. An incorrect value
930 will cause delays in the kernel to be wrong, leading to
931 unpredictable I/O errors and other breakage. Although
932 unlikely, in the extreme case this might damage your
933 hardware.
934
935 ltpc= [NET]
936 Format: <io>,<irq>,<dma>
937
a9913044
RD
938 mac5380= [HW,SCSI] Format:
939 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 940
a9913044
RD
941 mac53c9x= [HW,SCSI] Format:
942 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 943
a9913044
RD
944 machvec= [IA64] Force the use of a particular machine-vector
945 (machvec) in a generic kernel.
946 Example: machvec=hpzx1_swiotlb
1da177e4 947
a9913044 948 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
949 be mounted
950 Format: <1-256>
951
952 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
953 should make use of. maxcpus=n : n >= 0 limits the
954 kernel to using 'n' processors. n=0 is a special case,
955 it is equivalent to "nosmp", which also disables
956 the IO APIC.
1da177e4 957
2b2c3750
BP
958 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
959 equal to this physical address is ignored.
960
a9913044 961 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
962 Should be between 1 and 2^32-1.
963
964 max_report_luns=
a9913044 965 [SCSI] Maximum number of LUNs received.
1da177e4
LT
966 Should be between 1 and 16384.
967
cd4f0ef7 968 mca-pentium [BUGS=X86-32]
1da177e4
LT
969
970 mcatest= [IA-64]
971
cd4f0ef7 972 mce [X86-32] Machine Check Exception
1da177e4
LT
973
974 md= [HW] RAID subsystems devices and level
975 See Documentation/md.txt.
a9913044 976
1da177e4
LT
977 mdacon= [MDA]
978 Format: <first>,<last>
979 Specifies range of consoles to be captured by the MDA.
a9913044 980
1da177e4
LT
981 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
982 Amount of memory to be used when the kernel is not able
983 to see the whole system memory or for test.
cd4f0ef7 984 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
985 address space collisions. Without memmap= PCI devices
986 could be placed at addresses belonging to unused RAM.
987
cd4f0ef7 988 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
989 memory.
990
cd4f0ef7 991 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1da177e4
LT
992 E820 memory map, as specified by the user.
993 Such memmap=exactmap lines can be constructed based on
994 BIOS output or other requirements. See the memmap=nn@ss
995 option description.
996
997 memmap=nn[KMG]@ss[KMG]
998 [KNL] Force usage of a specific region of memory
999 Region of memory to be used, from ss to ss+nn.
1000
1001 memmap=nn[KMG]#ss[KMG]
1002 [KNL,ACPI] Mark specific memory as ACPI data.
1003 Region of memory to be used, from ss to ss+nn.
1004
1005 memmap=nn[KMG]$ss[KMG]
1006 [KNL,ACPI] Mark specific memory as reserved.
1007 Region of memory to be used, from ss to ss+nn.
1008
1009 meye.*= [HW] Set MotionEye Camera parameters
1010 See Documentation/video4linux/meye.txt.
1011
1012 mga= [HW,DRM]
1013
1014 mousedev.tap_time=
1015 [MOUSE] Maximum time between finger touching and
1016 leaving touchpad surface for touch to be considered
1017 a tap and be reported as a left button click (for
1018 touchpads working in absolute mode only).
1019 Format: <msecs>
1020 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1021 reporting absolute coordinates, such as tablets
1022 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1023 reporting absolute coordinates, such as tablets
1024
1025 mpu401= [HW,OSS]
1026 Format: <io>,<irq>
1027
1028 MTD_Partition= [MTD]
1029 Format: <name>,<region-number>,<size>,<offset>
1030
a9913044
RD
1031 MTD_Region= [MTD] Format:
1032 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1033
1034 mtdparts= [MTD]
c8facbb6 1035 See drivers/mtd/cmdlinepart.c.
1da177e4
LT
1036
1037 mtouchusb.raw_coordinates=
a9913044
RD
1038 [HW] Make the MicroTouch USB driver use raw coordinates
1039 ('y', default) or cooked coordinates ('n')
1da177e4
LT
1040
1041 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1042
1043 NCR_D700= [HW,SCSI]
1044 See header of drivers/scsi/NCR_D700.c.
1045
1046 ncr5380= [HW,SCSI]
1047
1048 ncr53c400= [HW,SCSI]
1049
1050 ncr53c400a= [HW,SCSI]
1051
1052 ncr53c406a= [HW,SCSI]
1053
1054 ncr53c8xx= [HW,SCSI]
1055
1056 netdev= [NET] Network devices parameters
1057 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1058 Note that mem_start is often overloaded to mean
1059 something different and driver-specific.
a9913044
RD
1060 This usage is only documented in each driver source
1061 file if at all.
1062
1da177e4
LT
1063 nfsaddrs= [NFS]
1064 See Documentation/nfsroot.txt.
1065
1066 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1067 See Documentation/nfsroot.txt.
1068
a72b4422
TM
1069 nfs.callback_tcpport=
1070 [NFS] set the TCP port on which the NFSv4 callback
1071 channel should listen.
1072
58df095b
TM
1073 nfs.idmap_cache_timeout=
1074 [NFS] set the maximum lifetime for idmapper cache
1075 entries.
1076
cd4f0ef7 1077 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1da177e4 1078
cd4f0ef7 1079 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1080 emulation library even if a 387 maths coprocessor
1081 is present.
1082
11ef697b
KCA
1083 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1084 when set.
1085 Format: <int>
1086
c1aee215
CL
1087 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1088 caches in the slab allocator. Saves per-node memory,
1089 but will impact performance.
3395ee05 1090
a9913044
RD
1091 noalign [KNL,ARM]
1092
1da177e4
LT
1093 noapic [SMP,APIC] Tells the kernel to not make use of any
1094 IOAPICs that may be present in the system.
1095
1096 noasync [HW,M68K] Disables async and sync negotiation for
1097 all devices.
1098
1099 nobats [PPC] Do not use BATs for mapping kernel lowmem
1100 on "Classic" PPC cores.
1101
1102 nocache [ARM]
a9913044 1103
163ecdff
SN
1104 nodelayacct [KNL] Disable per-task delay accounting
1105
1da177e4
LT
1106 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1107
1108 noexec [IA-64]
1109
cd4f0ef7 1110 noexec [X86-32,X86-64]
1da177e4
LT
1111 noexec=on: enable non-executable mappings (default)
1112 noexec=off: disable nn-executable mappings
1113
cd4f0ef7 1114 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1115 register save and restore. The kernel will only save
1116 legacy floating-point registers on task switch.
1da177e4
LT
1117
1118 nohlt [BUGS=ARM]
a9913044 1119
cd4f0ef7 1120 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1121 instruction doesn't work correctly and not to
1122 use it.
1123
1124 nohalt [IA-64] Tells the kernel not to use the power saving
1125 function PAL_HALT_LIGHT when idle. This increases
1126 power-consumption. On the positive side, it reduces
1127 interrupt wake-up latency, which may improve performance
1128 in certain environments such as networked servers or
1129 real-time systems.
1130
79bf2bb3
TG
1131 nohz= [KNL] Boottime enable/disable dynamic ticks
1132 Valid arguments: on, off
1133 Default: on
1134
cd4f0ef7 1135 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
8542b200 1136
cd4f0ef7 1137 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1138 disable unhandled interrupt sources.
1139
cd4f0ef7 1140 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
8542b200
ZA
1141 broken timer IRQ sources.
1142
1da177e4
LT
1143 noisapnp [ISAPNP] Disables ISA PnP code.
1144
1145 noinitrd [RAM] Tells the kernel not to load any configured
1146 initial RAM disk.
1147
1148 nointroute [IA-64]
1149
0aa366f3
TL
1150 nojitter [IA64] Disables jitter checking for ITC timers.
1151
cd4f0ef7 1152 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1153
cd4f0ef7 1154 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1155
1da177e4
LT
1156 noltlbs [PPC] Do not use large page/tlb entries for kernel
1157 lowmem mapping on PPC40x.
1158
312f1f01
H
1159 nomca [IA-64] Disable machine check abort handling
1160
cd4f0ef7 1161 nomce [X86-32] Machine Check Exception
abe37e5a 1162
83d7384f
AS
1163 nomfgpt [X86-32] Disable Multi-Function General Purpose
1164 Timer usage (for AMD Geode machines).
1165
cd4f0ef7 1166 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1167
cd4f0ef7 1168 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1169 with UP alternatives
1170
1da177e4
LT
1171 noresidual [PPC] Don't use residual data on PReP machines.
1172
a9913044
RD
1173 noresume [SWSUSP] Disables resume and restores original swap
1174 space.
1175
1da177e4
LT
1176 no-scroll [VGA] Disables scrollback.
1177 This is required for the Braillex ib80-piezo Braille
1178 reader made by F.H. Papenmeier (Germany).
1179
1180 nosbagart [IA-64]
1181
cd4f0ef7 1182 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1183
61ec7567
LB
1184 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1185 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1186
97842216
DJ
1187 nosoftlockup [KNL] Disable the soft-lockup detector.
1188
1da177e4
LT
1189 nosync [HW,M68K] Disables sync negotiation for all devices.
1190
cd4f0ef7 1191 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1192
1193 nousb [USB] Disable the USB subsystem
1194
1195 nowb [ARM]
a9913044 1196
f0c0b2b8
KH
1197 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1198 one of ['zone', 'node', 'default'] can be specified
1199 This can be set from sysctl after boot.
1200 See Documentation/sysctl/vm.txt for details.
1201
a61c2d78
DJ
1202 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1203
1da177e4
LT
1204 opl3= [HW,OSS]
1205 Format: <io>
1206
1da177e4
LT
1207 oprofile.timer= [HW]
1208 Use timer interrupt instead of performance counters
1209
1da177e4
LT
1210 osst= [HW,SCSI] SCSI Tape Driver
1211 Format: <buffer_size>,<write_threshold>
1212 See also Documentation/scsi/st.txt.
1213
1214 panic= [KNL] Kernel behaviour on panic
1215 Format: <timeout>
1216
1217 parkbd.port= [HW] Parallel port number the keyboard adapter is
1218 connected to, default is 0.
1219 Format: <parport#>
1220 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1221 0 for XT, 1 for AT (default is AT).
a9913044
RD
1222 Format: <mode>
1223
1224 parport= [HW,PPT] Specify parallel ports. 0 disables.
1225 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1226 Use 'auto' to force the driver to use any
1227 IRQ/DMA settings detected (the default is to
1228 ignore detected IRQ/DMA settings because of
1229 possible conflicts). You can specify the base
1230 address, IRQ, and DMA settings; IRQ and DMA
1231 should be numbers, or 'auto' (for using detected
1232 settings on that particular port), or 'nofifo'
1233 (to avoid using a FIFO even if it is detected).
1234 Parallel ports are assigned in the order they
1235 are specified on the command line, starting
1236 with parport0.
1237
1238 parport_init_mode= [HW,PPT]
1239 Configure VIA parallel port to operate in
1240 a specific mode. This is necessary on Pegasos
1241 computer where firmware has no options for setting
1242 up parallel port mode and sets it to spp.
1243 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1244 Format: [spp|ps2|epp|ecp|ecpepp]
1245
a9913044
RD
1246 pas2= [HW,OSS] Format:
1247 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1248
1da177e4
LT
1249 pas16= [HW,SCSI]
1250 See header of drivers/scsi/pas16.c.
1251
dd287796
AM
1252 pause_on_oops=
1253 Halt all CPUs after the first oops has been printed for
1254 the specified number of seconds. This is to be used if
1255 your oopses keep scrolling off the screen.
1256
1da177e4
LT
1257 pcbit= [HW,ISDN]
1258
1259 pcd. [PARIDE]
1260 See header of drivers/block/paride/pcd.c.
1261 See also Documentation/paride.txt.
1262
a9913044 1263 pci=option[,option...] [PCI] various PCI subsystem options:
cd4f0ef7
AC
1264 off [X86-32] don't probe for the PCI bus
1265 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1266 the hardware directly. Use this if your machine
1267 has a non-standard PCI host bridge.
cd4f0ef7 1268 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1269 hardware access methods are allowed. Use this
1270 if you experience crashes upon bootup and you
1271 suspect they are caused by the BIOS.
cd4f0ef7 1272 conf1 [X86-32] Force use of PCI Configuration
a9913044 1273 Mechanism 1.
cd4f0ef7 1274 conf2 [X86-32] Force use of PCI Configuration
a9913044 1275 Mechanism 2.
cd4f0ef7 1276 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
61be6d66 1277 Configuration
309e57df
MW
1278 nomsi [MSI] If the PCI_MSI kernel config parameter is
1279 enabled, this kernel boot option can be used to
1280 disable the use of MSI interrupts system-wide.
cd4f0ef7 1281 nosort [X86-32] Don't sort PCI devices according to
a9913044
RD
1282 order given by the PCI BIOS. This sorting is
1283 done to get a device order compatible with
1284 older kernels.
cd4f0ef7 1285 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1286 routing table. These calls are known to be buggy
1287 on several machines and they hang the machine
1288 when used, but on other computers it's the only
1289 way to get the interrupt routing table. Try
1290 this option if the kernel is unable to allocate
1291 IRQs or discover secondary PCI buses on your
1292 motherboard.
cd4f0ef7 1293 rom [X86-32] Assign address space to expansion ROMs.
a9913044
RD
1294 Use with caution as certain devices share
1295 address decoders between ROMs and other
1296 resources.
cd4f0ef7 1297 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
a9913044
RD
1298 assigned automatically to PCI devices. You can
1299 make the kernel exclude IRQs of your ISA cards
1300 this way.
cd4f0ef7 1301 pirqaddr=0xAAAAA [X86-32] Specify the physical address
a9913044
RD
1302 of the PIRQ table (normally generated
1303 by the BIOS) if it is outside the
1304 F0000h-100000h range.
cd4f0ef7 1305 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
a9913044
RD
1306 useful if the kernel is unable to find your
1307 secondary buses and you want to tell it
1308 explicitly which ones they are.
cd4f0ef7 1309 assign-busses [X86-32] Always assign all PCI bus
a9913044
RD
1310 numbers ourselves, overriding
1311 whatever the firmware may have done.
cd4f0ef7 1312 usepirqmask [X86-32] Honor the possible IRQ mask stored
a9913044
RD
1313 in the BIOS $PIR table. This is needed on
1314 some systems with broken BIOSes, notably
1315 some HP Pavilion N5400 and Omnibook XE3
1316 notebooks. This will have no effect if ACPI
1317 IRQ routing is enabled.
cd4f0ef7 1318 noacpi [X86-32] Do not use ACPI for IRQ routing
a9913044
RD
1319 or for PCI scanning.
1320 routeirq Do IRQ routing for all PCI devices.
1321 This is normally done in pci_enable_device(),
1322 so this option is a temporary workaround
1323 for broken drivers that don't call it.
1324 firmware [ARM] Do not re-enumerate the bus but instead
1325 just use the configuration from the
1326 bootloader. This is currently used on
1327 IXP2000 systems where the bus has to be
1328 configured a certain way for adjunct CPUs.
0637a70a
AK
1329 noearly [X86] Don't do any early type 1 scanning.
1330 This might help on some broken boards which
1331 machine check when some devices' config space
1332 is read. But various workarounds are disabled
1333 and some IOMMU drivers will not work.
6b4b78fe
MD
1334 bfsort Sort PCI devices into breadth-first order.
1335 This sorting is done to get a device
1336 order compatible with older (<= 2.4) kernels.
1337 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1338 cbiosize=nn[KMG] The fixed amount of bus space which is
1339 reserved for the CardBus bridge's IO window.
1340 The default value is 256 bytes.
1341 cbmemsize=nn[KMG] The fixed amount of bus space which is
1342 reserved for the CardBus bridge's memory
1343 window. The default value is 64 megabytes.
6b4b78fe 1344
1da177e4
LT
1345 pcmv= [HW,PCMCIA] BadgePAD 4
1346
1347 pd. [PARIDE]
1348 See Documentation/paride.txt.
1349
1350 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1351 boot time.
1352 Format: { 0 | 1 }
1353 See arch/parisc/kernel/pdc_chassis.c
1354
1355 pf. [PARIDE]
1356 See Documentation/paride.txt.
1357
1358 pg. [PARIDE]
1359 See Documentation/paride.txt.
1360
1361 pirq= [SMP,APIC] Manual mp-table setup
1362 See Documentation/i386/IO-APIC.txt.
1363
1364 plip= [PPT,NET] Parallel port network link
1365 Format: { parport<nr> | timid | 0 }
1366 See also Documentation/parport.txt.
1367
1368 pnpacpi= [ACPI]
1369 { off }
1370
1371 pnpbios= [ISAPNP]
1372 { on | off | curr | res | no-curr | no-res }
1373
1374 pnp_reserve_irq=
1375 [ISAPNP] Exclude IRQs for the autoconfiguration
1376
1377 pnp_reserve_dma=
1378 [ISAPNP] Exclude DMAs for the autoconfiguration
1379
1380 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1381 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1382
1383 pnp_reserve_mem=
a9913044
RD
1384 [ISAPNP] Exclude memory regions for the
1385 autoconfiguration.
1da177e4
LT
1386 Ranges are in pairs (memory base and size).
1387
45807a1d
IM
1388 print-fatal-signals=
1389 [KNL] debug: print fatal signals
1390 print-fatal-signals=1: print segfault info to
1391 the kernel console.
1392 default: off.
1393
e84845c4
RD
1394 printk.time= Show timing data prefixed to each printk message line
1395 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1396
1da177e4 1397 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1398 Format: [schedule,]<number>
1399 Param: "schedule" - profile schedule points.
1400 Param: <number> - step/bucket size as a power of 2 for
1401 statistical time based profiling.
ece8a684 1402 Param: "sleep" - profile D-state sleeping (millisecs)
1da177e4 1403
a9913044 1404 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1405 Limit processor to maximum C-state
1406 max_cstate=9 overrides any DMI blacklist limit.
1407
41c0d868
LB
1408 processor.nocst [HW,ACPI]
1409 Ignore the _CST method to determine C-states,
1410 instead using the legacy FADT method
1411
1da177e4
LT
1412 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1413 before loading.
1414 See Documentation/ramdisk.txt.
1415
a9913044
RD
1416 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1417 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1418 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1419 per second.
a9913044
RD
1420 psmouse.resetafter= [HW,MOUSE]
1421 Try to reset the device after so many bad packets
1da177e4
LT
1422 (0 = never).
1423 psmouse.resolution=
1424 [HW,MOUSE] Set desired mouse resolution, in dpi.
1425 psmouse.smartscroll=
a9913044 1426 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1427 0 = disabled, 1 = enabled (default).
1428
1429 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1430 Format:
1431 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1432
1433 pt. [PARIDE]
1434 See Documentation/paride.txt.
1435
7d2c502f 1436 quiet [KNL] Disable most log messages
a9913044 1437
1da177e4
LT
1438 r128= [HW,DRM]
1439
1440 raid= [HW,RAID]
1441 See Documentation/md.txt.
1442
1443 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1444 See Documentation/ramdisk.txt.
1445
a9913044 1446 ramdisk_blocksize= [RAM]
1da177e4 1447 See Documentation/ramdisk.txt.
a9913044 1448
1da177e4
LT
1449 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1450 New name for the ramdisk parameter.
1451 See Documentation/ramdisk.txt.
1452
21a1ea9e
DS
1453 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1454 RCU callbacks to process in one batch.
1455
1456 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1457 RCU callbacks over which batch limiting is disabled.
1458
1459 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1460 RCU callbacks below which batch limiting is re-enabled.
1461
ffdfc409
OJ
1462 rdinit= [KNL]
1463 Format: <full_path>
1464 Run specified binary instead of /init from the ramdisk,
1465 used for early userspace startup. See initrd.
1466
cd4f0ef7 1467 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1468 Format: <reboot_mode>[,<reboot_mode2>[,...]]
e53dd083 1469 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4
LT
1470
1471 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1472
cd4f0ef7 1473 reservetop= [X86-32]
461a9aff
ZA
1474 Format: nn[KMG]
1475 Reserves a hole at the top of the kernel virtual
1476 address space.
1477
7e96287d
VG
1478 reset_devices [KNL] Force drivers to reset the underlying device
1479 during initialization.
1480
a9913044
RD
1481 resume= [SWSUSP]
1482 Specify the partition device for software suspend
1da177e4 1483
ecbd0da1
RW
1484 resume_offset= [SWSUSP]
1485 Specify the offset from the beginning of the partition
1486 given by "resume=" at which the swap header is located,
1487 in <PAGE_SIZE> units (needed only for swap files).
1488 See Documentation/power/swsusp-and-swap-files.txt
1489
0a7b35cb
MN
1490 retain_initrd [RAM] Keep initrd memory after extraction
1491
1da177e4
LT
1492 rhash_entries= [KNL,NET]
1493 Set number of hash buckets for route cache
1494
1495 riscom8= [HW,SERIAL]
1496 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1497
1498 ro [KNL] Mount root device read-only on boot
1499
1500 root= [KNL] Root filesystem
1501
1502 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1503 mount the root filesystem
1504
1505 rootflags= [KNL] Set root filesystem mount option string
1506
1507 rootfstype= [KNL] Set root filesystem type
1508
cc1ed754
PO
1509 rootwait [KNL] Wait (indefinitely) for root device to show up.
1510 Useful for devices that are detected asynchronously
1511 (e.g. USB and MMC devices).
1512
1da177e4
LT
1513 rw [KNL] Mount root device read-write on boot
1514
1515 S [KNL] Run init in single mode
1516
1517 sa1100ir [NET]
1518 See drivers/net/irda/sa1100_ir.c.
1519
1520 sb= [HW,OSS]
1521 Format: <io>,<irq>,<dma>,<dma2>
1522
1523 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1524
1da177e4
LT
1525 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1526 Format: <io>[,<timeout>[,<isapnp>]]
1527
1528 scsi_debug_*= [SCSI]
1529 See drivers/scsi/scsi_debug.c.
1530
1531 scsi_default_dev_flags=
1532 [SCSI] SCSI default device flags
1533 Format: <integer>
1534
1535 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1536 Format: <vendor>:<model>:<flags>
1537 (flags are integer value)
1538
1539 scsi_logging= [SCSI]
1540
3e082a91
MW
1541 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1542 discovered. async scans them in kernel threads,
1543 allowing boot to proceed. none ignores them, expecting
1544 user space to do the scan.
1545
1da177e4
LT
1546 selinux [SELINUX] Disable or enable SELinux at boot time.
1547 Format: { "0" | "1" }
1548 See security/selinux/Kconfig help text.
1549 0 -- disable.
1550 1 -- enable.
1551 Default value is set via kernel config option.
1552 If enabled at boot time, /selinux/disable can be used
1553 later to disable prior to initial policy load.
1554
4e5ab4cb
JM
1555 selinux_compat_net =
1556 [SELINUX] Set initial selinux_compat_net flag value.
e53dd083
MCC
1557 Format: { "0" | "1" }
1558 0 -- use new secmark-based packet controls
1559 1 -- use legacy packet controls
1560 Default value is 0 (preferred).
1561 Value can be changed at runtime via
1562 /selinux/compat_net.
4e5ab4cb 1563
cd4f0ef7 1564 serialnumber [BUGS=X86-32]
1da177e4 1565
a9913044
RD
1566 sg_def_reserved_size= [SCSI]
1567
1da177e4
LT
1568 shapers= [NET]
1569 Maximal number of shapers.
a9913044 1570
1da177e4
LT
1571 sim710= [SCSI,HW]
1572 See header of drivers/scsi/sim710.c.
1573
1574 simeth= [IA-64]
1575 simscsi=
a9913044 1576
1da177e4
LT
1577 slram= [HW,MTD]
1578
f0630fff
CL
1579 slub_debug[=options[,slabs]] [MM, SLUB]
1580 Enabling slub_debug allows one to determine the
1581 culprit if slab objects become corrupted. Enabling
1582 slub_debug can create guard zones around objects and
1583 may poison objects when not in use. Also tracks the
1584 last alloc / free. For more information see
1585 Documentation/vm/slub.txt.
c1aee215
CL
1586
1587 slub_max_order= [MM, SLUB]
f0630fff
CL
1588 Determines the maximum allowed order for slabs.
1589 A high setting may cause OOMs due to memory
1590 fragmentation. For more information see
1591 Documentation/vm/slub.txt.
c1aee215
CL
1592
1593 slub_min_objects= [MM, SLUB]
f0630fff
CL
1594 The minimum number of objects per slab. SLUB will
1595 increase the slab order up to slub_max_order to
1596 generate a sufficiently large slab able to contain
1597 the number of objects indicated. The higher the number
1598 of objects the smaller the overhead of tracking slabs
1599 and the less frequently locks need to be acquired.
c1aee215
CL
1600 For more information see Documentation/vm/slub.txt.
1601
1602 slub_min_order= [MM, SLUB]
1603 Determines the mininum page order for slabs. Must be
f0630fff 1604 lower than slub_max_order.
c1aee215
CL
1605 For more information see Documentation/vm/slub.txt.
1606
1607 slub_nomerge [MM, SLUB]
f0630fff 1608 Disable merging of slabs with similar size. May be
c1aee215 1609 necessary if there is some reason to distinguish
f0630fff
CL
1610 allocs to different slabs. Debug options disable
1611 merging on their own.
c1aee215
CL
1612 For more information see Documentation/vm/slub.txt.
1613
1da177e4
LT
1614 smart2= [HW]
1615 Format: <io1>[,<io2>[,...,<io8>]]
1616
cd4f0ef7 1617 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
1618 attempt to substitute SMP alternatives once at boot.
1619
d0d4f69b
BH
1620 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1621 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1622 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1623 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1624 smsc-ircc2.ircc_irq= [HW] IRQ line
1625 smsc-ircc2.ircc_dma= [HW] DMA channel
1626 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1627 0: Toshiba Satellite 1800 (GP data pin select)
1628 1: Fast pin select (default)
1629 2: ATC IRMode
1630
1da177e4
LT
1631 snd-ad1816a= [HW,ALSA]
1632
1633 snd-ad1848= [HW,ALSA]
1634
1635 snd-ali5451= [HW,ALSA]
1636
1637 snd-als100= [HW,ALSA]
1638
1639 snd-als4000= [HW,ALSA]
1640
1641 snd-azt2320= [HW,ALSA]
1642
1643 snd-cmi8330= [HW,ALSA]
1644
1645 snd-cmipci= [HW,ALSA]
1646
1647 snd-cs4231= [HW,ALSA]
1648
1649 snd-cs4232= [HW,ALSA]
1650
1651 snd-cs4236= [HW,ALSA]
1652
1653 snd-cs4281= [HW,ALSA]
1654
1655 snd-cs46xx= [HW,ALSA]
1656
1657 snd-dt019x= [HW,ALSA]
1658
1659 snd-dummy= [HW,ALSA]
1660
1661 snd-emu10k1= [HW,ALSA]
1662
1663 snd-ens1370= [HW,ALSA]
1664
1665 snd-ens1371= [HW,ALSA]
1666
1667 snd-es968= [HW,ALSA]
1668
1669 snd-es1688= [HW,ALSA]
1670
1671 snd-es18xx= [HW,ALSA]
1672
1673 snd-es1938= [HW,ALSA]
1674
1675 snd-es1968= [HW,ALSA]
1676
1677 snd-fm801= [HW,ALSA]
1678
1679 snd-gusclassic= [HW,ALSA]
1680
1681 snd-gusextreme= [HW,ALSA]
1682
1683 snd-gusmax= [HW,ALSA]
1684
1685 snd-hdsp= [HW,ALSA]
1686
1687 snd-ice1712= [HW,ALSA]
1688
1689 snd-intel8x0= [HW,ALSA]
1690
1691 snd-interwave= [HW,ALSA]
1692
1693 snd-interwave-stb=
1694 [HW,ALSA]
1695
1696 snd-korg1212= [HW,ALSA]
1697
1698 snd-maestro3= [HW,ALSA]
1699
1700 snd-mpu401= [HW,ALSA]
1701
1702 snd-mtpav= [HW,ALSA]
1703
1704 snd-nm256= [HW,ALSA]
1705
1706 snd-opl3sa2= [HW,ALSA]
1707
1708 snd-opti92x-ad1848=
1709 [HW,ALSA]
1710
1711 snd-opti92x-cs4231=
1712 [HW,ALSA]
1713
1714 snd-opti93x= [HW,ALSA]
1715
1716 snd-pmac= [HW,ALSA]
1717
1718 snd-rme32= [HW,ALSA]
1719
1720 snd-rme96= [HW,ALSA]
1721
1722 snd-rme9652= [HW,ALSA]
1723
1724 snd-sb8= [HW,ALSA]
1725
1726 snd-sb16= [HW,ALSA]
1727
1728 snd-sbawe= [HW,ALSA]
1729
1730 snd-serial= [HW,ALSA]
1731
1732 snd-sgalaxy= [HW,ALSA]
1733
1734 snd-sonicvibes= [HW,ALSA]
1735
1736 snd-sun-amd7930=
1737 [HW,ALSA]
1738
1739 snd-sun-cs4231= [HW,ALSA]
1740
1741 snd-trident= [HW,ALSA]
1742
1743 snd-usb-audio= [HW,ALSA,USB]
1744
1745 snd-via82xx= [HW,ALSA]
1746
1747 snd-virmidi= [HW,ALSA]
1748
1749 snd-wavefront= [HW,ALSA]
1750
1751 snd-ymfpci= [HW,ALSA]
a9913044 1752
1da177e4
LT
1753 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1754 See Documentation/sonypi.txt
1755
1756 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1757 See Documentation/specialix.txt.
1758
1759 spia_io_base= [HW,MTD]
1760 spia_fio_base=
1761 spia_pedr=
1762 spia_peddr=
1763
1764 sscape= [HW,OSS]
1765 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1766
1da177e4
LT
1767 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1768 See Documentation/scsi/st.txt.
1769
1770 st0x= [HW,SCSI]
1771 See header of drivers/scsi/seagate.c.
1772
1773 sti= [PARISC,HW]
1774 Format: <num>
1775 Set the STI (builtin display/keyboard on the HP-PARISC
1776 machines) console (graphic card) which should be used
1777 as the initial boot-console.
1778 See also comment in drivers/video/console/sticore.c.
1779
1780 sti_font= [HW]
1781 See comment in drivers/video/console/sticore.c.
1782
1783 stifb= [HW]
1784 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1785
42a7fc4a
GB
1786 sunrpc.pool_mode=
1787 [NFS]
1788 Control how the NFS server code allocates CPUs to
1789 service thread pools. Depending on how many NICs
1790 you have and where their interrupts are bound, this
1791 option will affect which CPUs will do NFS serving.
1792 Note: this parameter cannot be changed while the
1793 NFS server is running.
1794
1795 auto the server chooses an appropriate mode
1796 automatically using heuristics
1797 global a single global pool contains all CPUs
1798 percpu one pool for each CPU
1799 pernode one pool for each NUMA node (equivalent
1800 to global on non-NUMA machines)
1801
1da177e4 1802 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1803
1da177e4
LT
1804 switches= [HW,M68k]
1805
1806 sym53c416= [HW,SCSI]
1807 See header of drivers/scsi/sym53c416.c.
1808
5d6f647f
IM
1809 sysrq_always_enabled
1810 [KNL]
1811 Ignore sysrq setting - this boot parameter will
1812 neutralize any effect of /proc/sys/kernel/sysrq.
1813 Useful for debugging.
1814
1da177e4
LT
1815 t128= [HW,SCSI]
1816 See header of drivers/scsi/t128.c.
1817
1818 tdfx= [HW,DRM]
1819
1820 thash_entries= [KNL,NET]
1821 Set number of hash buckets for TCP connection
1822
f8707ec9
LB
1823 thermal.act= [HW,ACPI]
1824 -1: disable all active trip points in all thermal zones
1825 <degrees C>: override all lowest active trip points
1826
c52a7419
LB
1827 thermal.crt= [HW,ACPI]
1828 -1: disable all critical trip points in all thermal zones
1829 <degrees C>: lower all critical trip points
1830
f5487145
LB
1831 thermal.nocrt= [HW,ACPI]
1832 Set to disable actions on ACPI thermal zone
1833 critical and hot trip points.
1834
72b33ef8
LB
1835 thermal.off= [HW,ACPI]
1836 1: disable ACPI thermal control
1837
a70cdc52
LB
1838 thermal.psv= [HW,ACPI]
1839 -1: disable all passive trip points
1840 <degrees C>: override all passive trip points to this value
1841
730ff34d
LB
1842 thermal.tzp= [HW,ACPI]
1843 Specify global default ACPI thermal zone polling rate
1844 <deci-seconds>: poll all this frequency
1845 0: no polling (default)
1846
1da177e4 1847 time Show timing data prefixed to each printk message line
e84845c4 1848 [deprecated, see 'printk.time']
1da177e4
LT
1849
1850 tipar.timeout= [HW,PPT]
1851 Set communications timeout in tenths of a second
1852 (default 15).
1853
1854 tipar.delay= [HW,PPT]
1855 Set inter-bit delay in microseconds (default 10).
1856
1857 tmc8xx= [HW,SCSI]
1858 See header of drivers/scsi/seagate.c.
1859
1860 tmscsim= [HW,SCSI]
1861 See comment before function dc390_setup() in
1862 drivers/scsi/tmscsim.c.
1863
1864 tp720= [HW,PS2]
1865
1866 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1867 Format:
1868 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1869
1da177e4
LT
1870 tsdev.xres= [TS] Horizontal screen resolution.
1871 tsdev.yres= [TS] Vertical screen resolution.
1872
a9913044
RD
1873 turbografx.map[2|3]= [HW,JOY]
1874 TurboGraFX parallel port interface
1875 Format:
1876 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1877 See also Documentation/input/joystick-parport.txt
1878
1879 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1880 See header of drivers/scsi/u14-34f.c.
1881
1882 uart401= [HW,OSS]
1883 Format: <io>,<irq>
1884
1885 uart6850= [HW,OSS]
1886 Format: <io>,<irq>
1887
5f8364b7
AS
1888 uhci-hcd.ignore_oc=
1889 [USB] Ignore overcurrent events (default N).
1890 Some badly-designed motherboards generate lots of
1891 bogus events, for ports that aren't wired to
1892 anything. Set this parameter to avoid log spamming.
1893 Note that genuine overcurrent events won't be
1894 reported either.
1895
b5e795f8
AS
1896 usbcore.autosuspend=
1897 [USB] The autosuspend time delay (in seconds) used
1898 for newly-detected USB devices (default 2). This
1899 is the time required before an idle device will be
1900 autosuspended. Devices for which the delay is set
eaafbc3a 1901 to a negative value won't be autosuspended at all.
b5e795f8 1902
1da177e4
LT
1903 usbhid.mousepoll=
1904 [USBHID] The interval which mice are to be polled at.
a9913044 1905
cd4f0ef7 1906 vdso= [X86-32,SH,x86-64]
1dbf527c 1907 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
1908 vdso=1: enable VDSO (default)
1909 vdso=0: disable VDSO mapping
1910
d080d397
YI
1911 vector= [IA-64,SMP]
1912 vector=percpu: enable percpu vector domain
1913
1da177e4
LT
1914 video= [FB] Frame buffer configuration
1915 See Documentation/fb/modedb.txt.
1916
cd4f0ef7 1917 vga= [BOOT,X86-32] Select a particular video mode
a9913044
RD
1918 See Documentation/i386/boot.txt and
1919 Documentation/svga.txt.
1da177e4
LT
1920 Use vga=ask for menu.
1921 This is actually a boot loader parameter; the value is
1922 passed to the kernel using a special protocol.
1923
a9913044 1924 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1925 size of <nn>. This can be used to increase the
1926 minimum size (128MB on x86). It can also be used to
1927 decrease the size and leave more room for directly
1928 mapped kernel RAM.
1929
585c3047
PO
1930 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1931 Format: <command>
1da177e4 1932
585c3047
PO
1933 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1934 Format: <command>
1935
1936 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1937 Format: <command>
a9913044 1938
1da177e4
LT
1939 waveartist= [HW,OSS]
1940 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1941
1da177e4
LT
1942 wd33c93= [HW,SCSI]
1943 See header of drivers/scsi/wd33c93.c.
1944
1945 wd7000= [HW,SCSI]
1946 See header of drivers/scsi/wd7000.c.
1947
1948 wdt= [WDT] Watchdog
8dfe9c21 1949 See Documentation/watchdog/wdt.txt.
1da177e4
LT
1950
1951 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1952 xd_geo= See header of drivers/block/xd.c.
1953
1954 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1955 Format:
1956 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1957
a62eaf15
AK
1958 norandmaps Don't use address space randomization
1959 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1960
e53dd083 1961 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
6d0185ea
JB
1962 This is useful to get more information why
1963 you got a "dwarf2 unwinder stuck"
1da177e4 1964
a9913044 1965______________________________________________________________________
1da177e4
LT
1966
1967TODO:
1968
1969 Add documentation for ALSA options.
1970 Add more DRM drivers.