Merge branch 'for-linus' of git://neil.brown.name/md
[deliverable/linux.git] / Documentation / kernel-parameters.txt
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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.
e7ba176b 37 AVR32 AVR32 architecture is enabled.
1da177e4 38 AX25 Appropriate AX.25 support is enabled.
0ae53640 39 BLACKFIN Blackfin architecture is enabled.
a9913044 40 DRM Direct Rendering Management support is enabled.
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41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
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46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
11ef697b 52 LIBATA Libata driver is enabled
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53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
309e57df 61 MSI Message Signaled Interrupts (PCI).
c8facbb6 62 MTD MTD (Memory Technology Device) support is enabled.
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63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
734efb46 65 GENERIC_TIME The generic timeofday code is enabled.
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66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
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68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
7f785763 72 PCIE PCI Express support is enabled.
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73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
20510f2f 79 ROOTPLUG The example Root Plug LSM is enabled.
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80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
20510f2f 84 SECURITY Different security models are enabled.
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85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
e523d93c 87 SH SuperH architecture is enabled.
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88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
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90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
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92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 100 X86-32 X86-32, aka i386 architecture is enabled.
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101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
71cced6e 103 Documentation/x86/x86_64/boot-options.txt .
c0115606 104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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105
106In addition, the following text indicates that the option:
107
108 BUGS= Relates to possible processor bugs on the said processor.
109 KNL Is a kernel start-up parameter.
110 BOOT Is a boot loader parameter.
111
112Parameters denoted with BOOT are actually interpreted by the boot
113loader, and have no meaning to the kernel directly.
114Do not modify the syntax of boot loader parameters without extreme
71cced6e 115need or coordination with <Documentation/x86/i386/boot.txt>.
1da177e4 116
5558870b 117There are also arch-specific kernel-parameters not documented here.
71cced6e 118See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 119
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120Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
121a trailing = on the name of any parameter states that that parameter will
122be entered as an environment variable, whereas its absence indicates that
123it will appear as a kernel argument readable via /proc/cmdline by programs
124running once the system is up.
125
9c4751fd 126The number of kernel parameters is not limited, but the length of the
127complete command line (parameters including spaces etc.) is limited to
128a fixed number of characters. This limit depends on the architecture
129and is between 256 and 4096 characters. It is defined in the file
130./include/asm/setup.h as COMMAND_LINE_SIZE.
131
132
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133 acpi= [HW,ACPI,X86-64,i386]
134 Advanced Configuration and Power Interface
a9913044 135 Format: { force | off | ht | strict | noirq }
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136 force -- enable ACPI if default was off
137 off -- disable ACPI if default was on
138 noirq -- do not use ACPI for IRQ routing
139 ht -- run only enough ACPI to enable Hyper Threading
a9913044 140 strict -- Be less tolerant of platforms that are not
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141 strictly ACPI specification compliant.
142
53471121 143 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 144
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145 acpi_apic_instance= [ACPI, IOAPIC]
146 Format: <int>
147 2: use 2nd APIC table, if available
148 1,0: use 1st APIC table
4e381a4f 149 default: 0
a1fdcc0d 150
1da177e4 151 acpi_sleep= [HW,ACPI] Sleep options
bdfe6b7c 152 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
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153 See Documentation/power/video.txt for s3_bios and s3_mode.
154 s3_beep is for debugging; it makes the PC's speaker beep
155 as soon as the kernel's real-mode entry point is called.
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156 s4_nohwsig prevents ACPI hardware signature from being
157 used during resume from hibernation.
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158 old_ordering causes the ACPI 1.0 ordering of the _PTS
159 control method, wrt putting devices into low power
160 states, to be enforced (the ACPI 2.0 ordering of _PTS is
161 used by default).
a9913044 162
1da177e4 163 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 164 Format: { level | edge | high | low }
1da177e4 165
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166 acpi_irq_balance [HW,ACPI]
167 ACPI will balance active IRQs
168 default in APIC mode
1da177e4 169
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170 acpi_irq_nobalance [HW,ACPI]
171 ACPI will not move active IRQs (default)
172 default in PIC mode
1da177e4 173
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174 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
175 use by PCI
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176 Format: <irq>,<irq>...
177
a9913044 178 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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179 Format: <irq>,<irq>...
180
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181 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
182
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183 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
184 Format: To spoof as Windows 98: ="Microsoft Windows"
185
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186 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
187 acpi_osi="string1" # add string1 -- only one string
188 acpi_osi="!string2" # remove built-in string2
189 acpi_osi= # disable all strings
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190
191 acpi_serialize [HW,ACPI] force serialization of AML methods
192
193 acpi_skip_timer_override [HW,ACPI]
194 Recognize and ignore IRQ0/pin2 Interrupt Override.
195 For broken nForce2 BIOS resulting in XT-PIC timer.
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196 acpi_use_timer_override [HW,ACPI}
197 Use timer override. For some broken Nvidia NF5 boards
198 that require a timer override, but don't have
199 HPET
1da177e4 200
f989106c 201 acpi.debug_layer= [HW,ACPI]
1da177e4 202 Format: <int>
a9913044 203 Each bit of the <int> indicates an ACPI debug layer,
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204 1: enable, 0: disable. It is useful for boot time
205 debugging. After system has booted up, it can be set
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206 via /sys/module/acpi/parameters/debug_layer.
207 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
208 Available bits (add the numbers together) to enable debug output
209 for specific parts of the ACPI subsystem:
210 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
211 0x10 namespace 0x20 parser 0x40 dispatcher
212 0x80 executer 0x100 resources 0x200 acpica debugger
213 0x400 os services 0x800 acpica disassembler.
214 The number can be in decimal or prefixed with 0x in hex.
215 Warning: Many of these options can produce a lot of
216 output and make your system unusable. Be very careful.
217
218 acpi.debug_level= [HW,ACPI]
1da177e4 219 Format: <int>
a9913044 220 Each bit of the <int> indicates an ACPI debug level,
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221 which corresponds to the level in an ACPI_DEBUG_PRINT
222 statement. After system has booted up, this mask
223 can be set via /sys/module/acpi/parameters/debug_level.
224
225 CONFIG_ACPI_DEBUG must be enabled for this to produce
226 any output. The number can be in decimal or prefixed
227 with 0x in hex. Some of these options produce so much
228 output that the system is unusable.
229
230 The following global components are defined by the
231 ACPI CA:
232 0x01 error
233 0x02 warn
234 0x04 init
235 0x08 debug object
236 0x10 info
237 0x20 init names
238 0x40 parse
239 0x80 load
240 0x100 dispatch
241 0x200 execute
242 0x400 names
243 0x800 operation region
244 0x1000 bfield
245 0x2000 tables
246 0x4000 values
247 0x8000 objects
248 0x10000 resources
249 0x20000 user requests
250 0x40000 package
251 The number can be in decimal or prefixed with 0x in hex.
252 Warning: Many of these options can produce a lot of
253 output and make your system unusable. Be very careful.
f989106c 254
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255 acpi.power_nocheck= [HW,ACPI]
256 Format: 1/0 enable/disable the check of power state.
257 On some bogus BIOS the _PSC object/_STA object of
258 power resource can't return the correct device power
259 state. In such case it is unneccessary to check its
260 power state again in power transition.
261 1 : disable the power state check
262
cd4f0ef7 263 acpi_pm_good [X86-32,X86-64]
5d0cf410 264 Override the pmtimer bug detection: force the kernel
265 to assume that this machine's pmtimer latches its value
266 and always returns good values.
267
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268 agp= [AGP]
269 { off | try_unsupported }
270 off: disable AGP support
271 try_unsupported: try to drive unsupported chipsets
272 (may crash computer or cause data corruption)
273
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274 enable_timer_pin_1 [i386,x86-64]
275 Enable PIN 1 of APIC timer
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276 Can be useful to work around chipset bugs
277 (in particular on some ATI chipsets).
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278 The kernel tries to set a reasonable default.
279
280 disable_timer_pin_1 [i386,x86-64]
281 Disable PIN 1 of APIC timer
282 Can be useful to work around chipset bugs.
283
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284 ad1848= [HW,OSS]
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
286
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287 advansys= [HW,SCSI]
288 See header of drivers/scsi/advansys.c.
289
290 advwdt= [HW,WDT] Advantech WDT
291 Format: <iostart>,<iostop>
292
293 aedsp16= [HW,OSS] Audio Excel DSP 16
294 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
295 See also header of sound/oss/aedsp16.c.
a9913044 296
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297 aha152x= [HW,SCSI]
298 See Documentation/scsi/aha152x.txt.
299
300 aha1542= [HW,SCSI]
301 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
302
303 aic7xxx= [HW,SCSI]
304 See Documentation/scsi/aic7xxx.txt.
305
306 aic79xx= [HW,SCSI]
307 See Documentation/scsi/aic79xx.txt.
308
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309 amd_iommu= [HW,X86-84]
310 Pass parameters to the AMD IOMMU driver in the system.
311 Possible values are:
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312 isolate - enable device isolation (each device, as far
313 as possible, will get its own protection
314 domain)
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315 fullflush - enable flushing of IO/TLB entries when
316 they are unmapped. Otherwise they are
317 flushed before they will be reused, which
318 is a lot of faster
319
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320 amd_iommu_size= [HW,X86-64]
321 Define the size of the aperture for the AMD IOMMU
322 driver. Possible values are:
323 '32M', '64M' (default), '128M', '256M', '512M', '1G'
324
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325 amijoy.map= [HW,JOY] Amiga joystick support
326 Map of devices attached to JOY0DAT and JOY1DAT
327 Format: <a>,<b>
328 See also Documentation/kernel/input/joystick.txt
329
330 analog.map= [HW,JOY] Analog joystick and gamepad support
331 Specifies type or capabilities of an analog joystick
332 connected to one of 16 gameports
333 Format: <type1>,<type2>,..<type16>
334
a9913044
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335 apc= [HW,SPARC]
336 Power management functions (SPARCstation-4/5 + deriv.)
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337 Format: noidle
338 Disable APC CPU standby support. SPARCstation-Fox does
339 not play well with APC CPU idle - disable it if you have
340 APC and your system crashes randomly.
341
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342 apic= [APIC,i386] Advanced Programmable Interrupt Controller
343 Change the output verbosity whilst booting
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344 Format: { quiet (default) | verbose | debug }
345 Change the amount of debugging information output
346 when initialising the APIC and IO-APIC components.
a9913044 347
1da177e4 348 apm= [APM] Advanced Power Management
71f77055 349 See header of arch/x86/kernel/apm_32.c.
1da177e4 350
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351 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
352 Format: <io>,<irq>,<nodeID>
353
354 ataflop= [HW,M68k]
355
356 atarimouse= [HW,MOUSE] Atari Mouse
357
358 atascsi= [HW,SCSI] Atari SCSI
359
360 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
361 EzKey and similar keyboards
362
363 atkbd.reset= [HW] Reset keyboard during initialization
364
a9913044
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365 atkbd.set= [HW] Select keyboard code set
366 Format: <int> (2 = AT (default), 3 = PS/2)
1da177e4
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367
368 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
369 keyboards
370
371 atkbd.softraw= [HW] Choose between synthetic and real raw mode
372 Format: <bool> (0 = real, 1 = synthetic (default))
a9913044
RD
373
374 atkbd.softrepeat= [HW]
375 Use software keyboard repeat
1da177e4
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376
377 autotest [IA64]
378
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379 baycom_epp= [HW,AX25]
380 Format: <io>,<mode>
a9913044 381
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382 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
383 Format: <io>,<mode>
384 See header of drivers/net/hamradio/baycom_par.c.
385
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386 baycom_ser_fdx= [HW,AX25]
387 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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388 Format: <io>,<irq>,<mode>[,<baud>]
389 See header of drivers/net/hamradio/baycom_ser_fdx.c.
390
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391 baycom_ser_hdx= [HW,AX25]
392 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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393 Format: <io>,<irq>,<mode>
394 See header of drivers/net/hamradio/baycom_ser_hdx.c.
395
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396 boot_delay= Milliseconds to delay each printk during boot.
397 Values larger than 10 seconds (10000) are changed to
398 no delay (0).
399 Format: integer
400
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401 bootmem_debug [KNL] Enable bootmem allocator debug messages.
402
1da177e4 403 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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404 bttv.radio= Most important insmod options are available as
405 kernel args too.
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406 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
407 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
408
409 BusLogic= [HW,SCSI]
410 See drivers/scsi/BusLogic.c, comment before function
411 BusLogic_ParseDriverOptions().
412
413 c101= [NET] Moxa C101 synchronous serial card
414
cd4f0ef7 415 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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LT
416 Sometimes CPU hardware bugs make them report the cache
417 size incorrectly. The kernel will attempt work arounds
418 to fix known problems, but for some CPUs it is not
419 possible to determine what the correct size should be.
420 This option provides an override for these situations.
421
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422 security= [SECURITY] Choose a security module to enable at boot.
423 If this boot parameter is not specified, only the first
424 security module asking for security registration will be
425 loaded. An invalid security module name will be treated
426 as if no module has been chosen.
427
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428 capability.disable=
429 [SECURITY] Disable capabilities. This would normally
430 be used only if an alternative security model is to be
431 configured. Potentially dangerous and should only be
432 used if you are entirely sure of the consequences.
433
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434 ccw_timeout_log [S390]
435 See Documentation/s390/CommonIO for details.
1da177e4 436
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437 cgroup_disable= [KNL] Disable a particular controller
438 Format: {name of the controller(s) to disable}
439 {Currently supported controllers - "memory"}
440
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LT
441 checkreqprot [SELINUX] Set initial checkreqprot flag value.
442 Format: { "0" | "1" }
443 See security/selinux/Kconfig help text.
a9913044
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444 0 -- check protection applied by kernel (includes
445 any implied execute protection).
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446 1 -- check protection requested by application.
447 Default value is set via a kernel config option.
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448 Value can be changed at runtime via
449 /selinux/checkreqprot.
450
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451 cio_ignore= [S390]
452 See Documentation/s390/CommonIO for details.
453
cd4f0ef7 454 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 455 [Deprecated]
3f6dee9b 456 Forces specified clocksource (if available) to be used
734efb46 457 when calculating gettimeofday(). If specified
3f6dee9b 458 clocksource is not available, it defaults to PIT.
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459 Format: { pit | tsc | cyclone | pmtmr }
460
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461 clocksource= [GENERIC_TIME] Override the default clocksource
462 Format: <string>
463 Override the default clocksource and use the clocksource
464 with the name specified.
465 Some clocksource names to choose from, depending on
466 the platform:
467 [all] jiffies (this is the base, fallback clocksource)
468 [ACPI] acpi_pm
469 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
470 pxa_timer,timer3,32k_counter,timer0_1
471 [AVR32] avr32
cd4f0ef7 472 [X86-32] pit,hpet,tsc,vmi-timer;
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RD
473 scx200_hrt on Geode; cyclone on IBM x440
474 [MIPS] MIPS
475 [PARISC] cr16
476 [S390] tod
477 [SH] SuperH
478 [SPARC64] tick
479 [X86-64] hpet,tsc
480
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481 clearcpuid=BITNUM [X86]
482 Disable CPUID feature X for the kernel. See
483 include/asm-x86/cpufeature.h for the valid bit numbers.
484 Note the Linux specific bits are not necessarily
485 stable over kernel options, but the vendor specific
486 ones should be.
487 Also note that user programs calling CPUID directly
488 or using the feature without checking anything
489 will still see it. This just prevents it from
490 being used by the kernel or shown in /proc/cpuinfo.
491 Also note the kernel might malfunction if you disable
492 some critical bits.
493
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494 code_bytes [IA32/X86_64] How many bytes of object code to print
495 in an oops report.
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CE
496 Range: 0 - 8192
497 Default: 64
498
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TG
499 hpet= [X86-32,HPET] option to control HPET usage
500 Format: { enable (default) | disable | force }
501 disable: disable HPET and use PIT instead
d79a5f80
CC
502 force: allow force enabled of undocumented chips (ICH4,
503 VIA, nVidia)
1da177e4 504
1da177e4 505 com20020= [HW,NET] ARCnet - COM20020 chipset
a9913044
RD
506 Format:
507 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
1da177e4
LT
508
509 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
510 Format: <io>[,<irq>]
511
a9913044
RD
512 com90xx= [HW,NET]
513 ARCnet - COM90xx chipset (memory-mapped buffers)
1da177e4
LT
514 Format: <io>[,<irq>[,<memstart>]]
515
516 condev= [HW,S390] console device
517 conmode=
a9913044 518
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LT
519 console= [KNL] Output console device and options.
520
521 tty<n> Use the virtual console device <n>.
522
523 ttyS<n>[,options]
f1a1c2dc 524 ttyUSB0[,options]
1da177e4 525 Use the specified serial port. The options are of
f1a1c2dc
RD
526 the form "bbbbpnf", where "bbbb" is the baud rate,
527 "p" is parity ("n", "o", or "e"), "n" is number of
528 bits, and "f" is flow control ("r" for RTS or
529 omit it). Default is "9600n8".
530
531 See Documentation/serial-console.txt for more
532 information. See
533 Documentation/networking/netconsole.txt for an
534 alternative.
1da177e4 535
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YL
536 uart[8250],io,<addr>[,options]
537 uart[8250],mmio,<addr>[,options]
1da177e4
LT
538 Start an early, polled-mode console on the 8250/16550
539 UART at the specified I/O port or MMIO address,
540 switching to the matching ttyS device later. The
541 options are the same as for ttyS, above.
542
f7511d5f
ST
543 If the device connected to the port is not a TTY but a braille
544 device, prepend "brl," before the device type, for instance
545 console=brl,ttyS0
546 For now, only VisioBraille is supported.
547
18a8bd94
YL
548 earlycon= [KNL] Output early console device and options.
549 uart[8250],io,<addr>[,options]
550 uart[8250],mmio,<addr>[,options]
551 Start an early, polled-mode console on the 8250/16550
552 UART at the specified I/O port or MMIO address.
553 The options are the same as for ttyS, above.
554
8f4ce8c3
AS
555 no_console_suspend
556 [HW] Never suspend the console
557 Disable suspending of consoles during suspend and
558 hibernate operations. Once disabled, debugging
559 messages can reach various consoles while the rest
560 of the system is being put to sleep (ie, while
561 debugging driver suspend/resume hooks). This may
562 not work reliably with all consoles, but is known
563 to work with serial and VGA consoles.
564
1da177e4 565 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
566 Format:
567 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 568
dc009d92
EB
569 crashkernel=nn[KMG]@ss[KMG]
570 [KNL] Reserve a chunk of physical memory to
571 hold a kernel to switch to with kexec on panic.
572
fb391599
BW
573 crashkernel=range1:size1[,range2:size2,...][@offset]
574 [KNL] Same as above, but depends on the memory
575 in the running system. The syntax of range is
576 start-[end] where start and end are both
577 a memory unit (amount[KMG]). See also
578 Documentation/kdump/kdump.txt for a example.
579
1da177e4
LT
580 cs4232= [HW,OSS]
581 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
582
583 cs89x0_dma= [HW,NET]
584 Format: <dma>
585
586 cs89x0_media= [HW,NET]
587 Format: { rj45 | aui | bnc }
a9913044 588
a9913044 589 dasd= [HW,NET]
1da177e4
LT
590 See header of drivers/s390/block/dasd_devmap.c.
591
592 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
593 (one device per port)
594 Format: <port#>,<type>
595 See also Documentation/input/joystick-parport.txt
596
597 debug [KNL] Enable kernel debugging (events log level).
598
cae2ed9a
IM
599 debug_locks_verbose=
600 [KNL] verbose self-tests
601 Format=<0|1>
602 Print debugging info while doing the locking API
603 self-tests.
604 We default to 0 (no extra messages), setting it to
605 1 will print _a lot_ more information - normally
606 only useful to kernel developers.
607
3ac7fe5a
TG
608 debug_objects [KNL] Enable object debugging
609
d3af01f1
TG
610 debugpat [X86] Enable PAT debugging
611
2d27a966 612 decnet.addr= [HW,NET]
1da177e4
LT
613 Format: <area>[,<node>]
614 See also Documentation/networking/decnet.txt.
615
ecb77fa9 616 vt.default_blu= [VT]
55ff9780
AD
617 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
618 Change the default blue palette of the console.
619 This is a 16-member array composed of values
620 ranging from 0-255.
621
ecb77fa9 622 vt.default_grn= [VT]
55ff9780
AD
623 Format: <green0>,<green1>,<green2>,...,<green15>
624 Change the default green palette of the console.
625 This is a 16-member array composed of values
626 ranging from 0-255.
627
ecb77fa9 628 vt.default_red= [VT]
55ff9780
AD
629 Format: <red0>,<red1>,<red2>,...,<red15>
630 Change the default red palette of the console.
631 This is a 16-member array composed of values
632 ranging from 0-255.
633
ecb77fa9
ST
634 vt.default_utf8=
635 [VT]
55ff9780
AD
636 Format=<0|1>
637 Set system-wide default UTF-8 mode for all tty's.
ecb77fa9
ST
638 Default is 1, i.e. UTF-8 mode is enabled for all
639 newly opened terminals.
55ff9780 640
1da177e4
LT
641 dhash_entries= [KNL]
642 Set number of hash buckets for dentry cache.
a9913044 643
1da177e4
LT
644 digi= [HW,SERIAL]
645 IO parameters + enable/disable command.
646
647 digiepca= [HW,SERIAL]
648 See drivers/char/README.epca and
649 Documentation/digiepca.txt.
650
95ffa243
YL
651 disable_mtrr_cleanup [X86]
652 enable_mtrr_cleanup [X86]
653 The kernel tries to adjust MTRR layout from continuous
654 to discrete, to make X server driver able to add WB
655 entry later. This parameter enables/disables that.
656
657 mtrr_chunk_size=nn[KMG] [X86]
658 used for mtrr cleanup. It is largest continous chunk
659 that could hold holes aka. UC entries.
660
661 mtrr_gran_size=nn[KMG] [X86]
12031a62
YL
662 Used for mtrr cleanup. It is granularity of mtrr block.
663 Default is 1.
664 Large value could prevent small alignment from
665 using up MTRRs.
666
667 mtrr_spare_reg_nr=n [X86]
668 Format: <integer>
669 Range: 0,7 : spare reg number
670 Default : 1
671 Used for mtrr cleanup. It is spare mtrr entries number.
672 Set to 2 or more if your graphical card needs more.
95ffa243 673
093af8d7 674 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
675 By default the kernel will trim any uncacheable
676 memory out of your available memory pool based on
677 MTRR settings. This parameter disables that behavior,
678 possibly causing your machine to run very slowly.
679
1da177e4
LT
680 dmasound= [HW,OSS] Sound subsystem buffers
681
682 dscc4.setup= [NET]
683
684 dtc3181e= [HW,SCSI]
685
0ae53640 686 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
1da177e4
LT
687 earlyprintk=vga
688 earlyprintk=serial[,ttySn[,baudrate]]
5c05917e 689 earlyprintk=dbgp
1da177e4 690
a9913044 691 Append ",keep" to not disable it when the real console
1da177e4
LT
692 takes over.
693
5c05917e 694 Only vga or serial or usb debug port at a time.
1da177e4
LT
695
696 Currently only ttyS0 and ttyS1 are supported.
697
698 Interaction with the standard serial driver is not
699 very good.
700
701 The VGA output is eventually overwritten by the real
702 console.
703
704 eata= [HW,SCSI]
705
1da177e4 706 edd= [EDD]
8c4dd606 707 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 708
1da177e4
LT
709 eisa_irq_edge= [PARISC,HW]
710 See header of drivers/parisc/eisa.c.
711
cd4f0ef7 712 elanfreq= [X86-32]
1da177e4 713 See comment before function elanfreq_setup() in
71f77055 714 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
715
716 elevator= [IOSCHED]
16ab3adf 717 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
718 See Documentation/block/as-iosched.txt and
719 Documentation/block/deadline-iosched.txt for details.
720
e515a0d6 721 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
a9913044 722 Specifies physical address of start of kernel core
aac04b32
VG
723 image elf header. Generally kexec loader will
724 pass this option to capture kernel.
725 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
726
727 enforcing [SELINUX] Set initial enforcing status.
728 Format: {"0" | "1"}
729 See security/selinux/Kconfig help text.
730 0 -- permissive (log only, no denials).
731 1 -- enforcing (deny and log).
732 Default value is 0.
733 Value can be changed at runtime via /selinux/enforce.
734
1da177e4
LT
735 es1371= [HW,OSS]
736 Format: <spdif>,[<nomix>,[<amplifier>]]
737 See also header of sound/oss/es1371.c.
a9913044 738
1da177e4
LT
739 ether= [HW,NET] Ethernet cards parameters
740 This option is obsoleted by the "netdev=" option, which
741 has equivalent usage. See its documentation for details.
742
743 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
744 Format: <io>[,<irq>]
745
de1ba09b
AM
746 failslab=
747 fail_page_alloc=
748 fail_make_request=[KNL]
749 General fault injection mechanism.
750 Format: <interval>,<probability>,<space>,<times>
751 See also /Documentation/fault-injection/.
752
1da177e4
LT
753 fd_mcs= [HW,SCSI]
754 See header of drivers/scsi/fd_mcs.c.
755
756 fdomain= [HW,SCSI]
757 See header of drivers/scsi/fdomain.c.
758
759 floppy= [HW]
760 See Documentation/floppy.txt.
761
f13ae30e
AC
762 force_pal_cache_flush
763 [IA-64] Avoid check_sal_cache_flush which may hang on
764 buggy SAL_CACHE_FLUSH implementations. Using this
765 parameter will force ia64_sal_cache_flush to call
766 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
767
1da177e4
LT
768 gamecon.map[2|3]=
769 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
770 support via parallel port (up to 5 devices per port)
771 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
772 See also Documentation/input/joystick-parport.txt
773
774 gamma= [HW,DRM]
775
aaf23042
YL
776 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
777 Format: off | on
778 default: on
779
1da177e4
LT
780 gdth= [HW,SCSI]
781 See header of drivers/scsi/gdth.c.
782
783 gpt [EFI] Forces disk with valid GPT signature but
784 invalid Protective MBR to be treated as GPT.
785
1da177e4
LT
786 gvp11= [HW,SCSI]
787
788 hashdist= [KNL,NUMA] Large hashes allocated during boot
789 are distributed across NUMA nodes. Defaults on
790 for IA-64, off otherwise.
a9913044 791 Format: 0 | 1 (for off | on)
1da177e4
LT
792
793 hcl= [IA-64] SGI's Hardware Graph compatibility layer
794
795 hd= [EIDE] (E)IDE hard drive subsystem geometry
796 Format: <cyl>,<head>,<sect>
797
1da177e4
LT
798 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
799 size of <nn>. This works even on boxes that have no
800 highmem otherwise. This also works to reduce highmem
801 size on bigger boxes.
802
54cdfdb4
TG
803 highres= [KNL] Enable/disable high resolution timer mode.
804 Valid parameters: "on", "off"
805 Default: "on"
806
1da177e4
LT
807 hisax= [HW,ISDN]
808 See Documentation/isdn/README.HiSax.
809
b4718e62
AK
810 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
811 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
812 On x86-64 and powerpc, this option can be specified
813 multiple times interleaved with hugepages= to reserve
814 huge pages of different sizes. Valid pages sizes on
815 x86-64 are 2M (when the CPU supports "pse") and 1G
816 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
817 Note that 1GB pages can only be allocated at boot time
818 using hugepages= and not freed afterwards.
e11bfbfc
NP
819 default_hugepagesz=
820 [same as hugepagesz=] The size of the default
821 HugeTLB page size. This is the size represented by
822 the legacy /proc/ hugepages APIs, used for SHM, and
823 default size when mounting hugetlbfs filesystems.
824 Defaults to the default architecture's huge page size
825 if not specified.
1da177e4 826
6902aa84
PM
827 hlt [BUGS=ARM,SH]
828
36d95739 829 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 830 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
831 i8042.dumbkbd [HW] Pretend that controller can only read data from
832 keyboard and cannot control its state
1da177e4
LT
833 (Don't attempt to blink the leds)
834 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 835 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
836 i8042.noloop [HW] Disable the AUX Loopback command while probing
837 for the AUX port
1da177e4
LT
838 i8042.nomux [HW] Don't check presence of an active multiplexing
839 controller
840 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
841 controllers
842 i8042.panicblink=
843 [HW] Frequency with which keyboard LEDs should blink
844 when kernel panics (default is 0.5 sec)
845 i8042.reset [HW] Reset the controller during init and cleanup
846 i8042.unlock [HW] Unlock (ignore) the keylock
847
848 i810= [HW,DRM]
849
e70c9d5e
DT
850 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
851 indicates that the driver is running on unsupported
852 hardware.
1da177e4
LT
853 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
854 does not match list of supported models.
855 i8k.power_status
856 [HW] Report power status in /proc/i8k
857 (disabled by default)
858 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
859 capability is set.
860
861 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
862 See Documentation/mca.txt.
863
864 icn= [HW,ISDN]
865 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
866
867 ide= [HW] (E)IDE subsystem
a594eeb1 868 Format: ide=nodma or ide=doubler
1c10e938 869 See Documentation/ide/ide.txt.
1da177e4 870
1da177e4 871 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
1c10e938 872 See Documentation/ide/ide.txt.
1da177e4 873
f039b754 874 idle= [X86]
da5e09a1 875 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
f039b754
AK
876 Poll forces a polling idle loop that can slightly improves the performance
877 of waking up a idle CPU, but will use a lot of power and make the system
878 run hot. Not recommended.
879 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
880 to not use it because it doesn't save as much power as a normal idle
881 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
882 as idle=poll.
c1e3b377
ZY
883 idle=halt. Halt is forced to be used for CPU idle.
884 In such case C2/C3 won't be used again.
da5e09a1 885 idle=nomwait. Disable mwait for CPU C-states
a9913044 886
594765a7
DC
887 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
888 Claim all unknown PCI IDE storage controllers.
889
79290822
IM
890 ignore_loglevel [KNL]
891 Ignore loglevel setting - this will print /all/
892 kernel messages to the console. Useful for debugging.
893
1da177e4
LT
894 ihash_entries= [KNL]
895 Set number of hash buckets for inode cache.
896
897 in2000= [HW,SCSI]
898 See header of drivers/scsi/in2000.c.
899
900 init= [KNL]
901 Format: <full_path>
902 Run specified binary instead of /sbin/init as init
903 process.
904
905 initcall_debug [KNL] Trace initcalls as they are executed. Useful
906 for working out where the kernel is dying during
907 startup.
908
909 initrd= [BOOT] Specify the location of the initial ramdisk
910
911 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
912 Format: <irq>
913
914 inttest= [IA64]
915
b552da87
PM
916 iommu= [x86]
917 off
918 force
919 noforce
920 biomerge
921 panic
922 nopanic
923 merge
924 nomerge
925 forcesac
926 soft
927
928
ba395927
KA
929 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
930 off
931 Disable intel iommu driver.
932 igfx_off [Default Off]
933 By default, gfx is mapped as normal device. If a gfx
934 device has a dedicated DMAR unit, the DMAR unit is
935 bypassed by not enabling DMAR with this option. In
936 this case, gfx device will use physical address for
937 DMA.
7d3b03ce
KA
938 forcedac [x86_64]
939 With this option iommu will not optimize to look
940 for io virtual address below 32 bit forcing dual
941 address cycle on pci bus for cards supporting greater
942 than 32 bit addressing. The default is to look
943 for translation below 32 bit and if not available
944 then look in the higher range.
5e0d2a6f 945 strict [Default Off]
946 With this option on every unmap_single operation will
947 result in a hardware IOTLB flush operation as opposed
948 to batching them for performance.
ba395927 949
b02aae9c 950 io_delay= [X86-32,X86-64] I/O delay method
6e7c4025
IM
951 0x80
952 Standard port 0x80 based delay
953 0xed
954 Alternate port 0xed based delay (needed on some systems)
b02aae9c 955 udelay
6e7c4025
IM
956 Simple two microseconds delay
957 none
958 No delay
b02aae9c 959
1da177e4
LT
960 io7= [HW] IO7 for Marvel based alpha systems
961 See comment before marvel_specify_io7 in
962 arch/alpha/kernel/core_marvel.c.
963
964 ip= [IP_PNP]
6ded55da 965 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
966
967 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
968 See comment before ip2_setup() in
969 drivers/char/ip2/ip2base.c.
1da177e4
LT
970
971 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
972 See header of drivers/scsi/ips.c.
973
72c4a13a
SH
974 ports= [IP_VS_FTP] IPVS ftp helper module
975 Default is 21.
976 Up to 8 (IP_VS_APP_MAX_PORTS) ports
977 may be specified.
978 Format: <port>,<port>....
979
200803df
AC
980 irqfixup [HW]
981 When an interrupt is not handled search all handlers
982 for it. Intended to get systems with badly broken
983 firmware running.
984
985 irqpoll [HW]
986 When an interrupt is not handled search all handlers
987 for it. Also check all handlers each timer
988 interrupt. Intended to get systems with badly broken
989 firmware running.
990
1da177e4 991 isapnp= [ISAPNP]
a9913044 992 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
993
994 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
995 Format:
996 <cpu number>,...,<cpu number>
997 or
b225d44e
LZ
998 <cpu number>-<cpu number>
999 (must be a positive range in ascending order)
22f2e280
DF
1000 or a mixture
1001 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 1002
1da177e4
LT
1003 This option can be used to specify one or more CPUs
1004 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
1005 algorithms. You can move a process onto or off an
1006 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
1007 <cpu number> begins at 0 and the maximum value is
1008 "number of CPUs in system - 1".
1009
1010 This option is the preferred way to isolate CPUs. The
a9913044
RD
1011 alternative -- manually setting the CPU mask of all
1012 tasks in the system -- can cause problems and
1013 suboptimal load balancer performance.
1da177e4 1014
a9913044 1015 iucv= [HW,NET]
1da177e4
LT
1016
1017 js= [HW,JOY] Analog joystick
1018 See Documentation/input/joystick.txt.
1019
cd4f0ef7 1020 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
ed7ed365
MG
1021 specifies the amount of memory usable by the kernel
1022 for non-movable allocations. The requested amount is
1023 spread evenly throughout all nodes in the system. The
1024 remaining memory in each node is used for Movable
1025 pages. In the event, a node is too small to have both
1026 kernelcore and Movable pages, kernelcore pages will
1027 take priority and other nodes will have a larger number
1028 of kernelcore pages. The Movable zone is used for the
1029 allocation of pages that may be reclaimed or moved
1030 by the page migration subsystem. This means that
1031 HugeTLB pages may not be allocated from this zone.
1032 Note that allocations like PTEs-from-HighMem still
1033 use the HighMem zone if it exists, and the Normal
1034 zone if it does not.
1035
cd4f0ef7 1036 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
7e63efef
MG
1037 is similar to kernelcore except it specifies the
1038 amount of memory used for migratable allocations.
1039 If both kernelcore and movablecore is specified,
1040 then kernelcore will be at *least* the specified
1041 value but may be more. If movablecore on its own
1042 is specified, the administrator must be careful
1043 that the amount of memory usable for all allocations
1044 is not too small.
1045
1da177e4
LT
1046 keepinitrd [HW,ARM]
1047
cd4f0ef7 1048 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1da177e4
LT
1049 in oops dumps.
1050
6cdf6e06
JW
1051 kgdboc= [HW] kgdb over consoles.
1052 Requires a tty driver that supports console polling.
1053 (only serial suported for now)
1054 Format: <serial_device>[,baud]
1055
9bed90c6
FF
1056 kmac= [MIPS] korina ethernet MAC address.
1057 Configure the RouterBoard 532 series on-chip
1058 Ethernet adapter MAC address.
1059
1da177e4
LT
1060 l2cr= [PPC]
1061
a78bfbfc
RB
1062 l3cr= [PPC]
1063
cd4f0ef7 1064 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1065 disabled it.
1da177e4 1066
cd4f0ef7 1067 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
e585bef8
TG
1068 C2 power state.
1069
fcb71f6f
FC
1070 libata.dma= [LIBATA] DMA control
1071 libata.dma=0 Disable all PATA and SATA DMA
1072 libata.dma=1 PATA and SATA Disk DMA only
1073 libata.dma=2 ATAPI (CDROM) DMA only
1074 libata.dma=4 Compact Flash DMA only
1075 Combinations also work, so libata.dma=3 enables DMA
1076 for disks and CDROMs, but not CFs.
1077
78e70c23
DJ
1078 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1079 when set.
1080 Format: <int>
1081
33267325
TH
1082 libata.force= [LIBATA] Force configurations. The format is comma
1083 separated list of "[ID:]VAL" where ID is
1084 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1085 matching port, link or device. Basically, it matches
1086 the ATA ID string printed on console by libata. If
1087 the whole ID part is omitted, the last PORT and DEVICE
1088 values are used. If ID hasn't been specified yet, the
1089 configuration applies to all ports, links and devices.
1090
1091 If only DEVICE is omitted, the parameter applies to
1092 the port and all links and devices behind it. DEVICE
1093 number of 0 either selects the first device or the
1094 first fan-out link behind PMP device. It does not
1095 select the host link. DEVICE number of 15 selects the
1096 host link and device attached to it.
1097
1098 The VAL specifies the configuration to force. As long
1099 as there's no ambiguity shortcut notation is allowed.
1100 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1101 The following configurations can be forced.
1102
1103 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1104 Any ID with matching PORT is used.
1105
1106 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1107
1108 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1109 udma[/][16,25,33,44,66,100,133] notation is also
1110 allowed.
1111
1112 * [no]ncq: Turn on or off NCQ.
1113
05944bdf
TH
1114 * nohrst, nosrst, norst: suppress hard, soft
1115 and both resets.
1116
33267325
TH
1117 If there are multiple matching configurations changing
1118 the same attribute, the last one is used.
1119
1da177e4
LT
1120 load_ramdisk= [RAM] List of ramdisks to load from floppy
1121 See Documentation/ramdisk.txt.
1122
a6b25b67
RD
1123 lockd.nlm_grace_period=P [NFS] Assign grace period.
1124 Format: <integer>
1da177e4 1125
a6b25b67
RD
1126 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1127 Format: <integer>
1128
1129 lockd.nlm_timeout=T [NFS] Assign timeout value.
1130 Format: <integer>
1131
1132 lockd.nlm_udpport=M [NFS] Assign UDP port.
1133 Format: <integer>
1da177e4
LT
1134
1135 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1136 Format: <irq>
1137
1138 loglevel= All Kernel Messages with a loglevel smaller than the
1139 console loglevel will be printed to the console. It can
1140 also be changed with klogd or other programs. The
1141 loglevels are defined as follows:
1142
1143 0 (KERN_EMERG) system is unusable
1144 1 (KERN_ALERT) action must be taken immediately
1145 2 (KERN_CRIT) critical conditions
1146 3 (KERN_ERR) error conditions
1147 4 (KERN_WARNING) warning conditions
1148 5 (KERN_NOTICE) normal but significant condition
1149 6 (KERN_INFO) informational
1150 7 (KERN_DEBUG) debug-level messages
1151
1152 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1153 Format: { n | nk | nM }
1154 n must be a power of two. The default size
1155 is set in the kernel config file.
1da177e4 1156
accaa24c
RD
1157 logo.nologo [FB] Disables display of the built-in Linux logo.
1158 This may be used to provide more screen space for
1159 kernel log messages and is useful when debugging
1160 kernel boot problems.
1161
1da177e4
LT
1162 lp=0 [LP] Specify parallel ports to use, e.g,
1163 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1164 lp=reset first parallel port). 'lp=0' disables the
1165 lp=auto printer driver. 'lp=reset' (which can be
1166 specified in addition to the ports) causes
1167 attached printers to be reset. Using
1168 lp=port1,port2,... specifies the parallel ports
1169 to associate lp devices with, starting with
1170 lp0. A port specification may be 'none' to skip
1171 that lp device, or a parport name such as
1172 'parport0'. Specifying 'lp=auto' instead of a
1173 port specification list means that device IDs
1174 from each port should be examined, to see if
1175 an IEEE 1284-compliant printer is attached; if
1176 so, the driver will manage that printer.
1177 See also header of drivers/char/lp.c.
1178
1179 lpj=n [KNL]
1180 Sets loops_per_jiffy to given constant, thus avoiding
1181 time-consuming boot-time autodetection (up to 250 ms per
1182 CPU). 0 enables autodetection (default). To determine
1183 the correct value for your kernel, boot with normal
1184 autodetection and see what value is printed. Note that
1185 on SMP systems the preset will be applied to all CPUs,
1186 which is likely to cause problems if your CPUs need
1187 significantly divergent settings. An incorrect value
1188 will cause delays in the kernel to be wrong, leading to
1189 unpredictable I/O errors and other breakage. Although
1190 unlikely, in the extreme case this might damage your
1191 hardware.
1192
1193 ltpc= [NET]
1194 Format: <io>,<irq>,<dma>
1195
a9913044
RD
1196 mac5380= [HW,SCSI] Format:
1197 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1198
a9913044
RD
1199 machvec= [IA64] Force the use of a particular machine-vector
1200 (machvec) in a generic kernel.
1201 Example: machvec=hpzx1_swiotlb
1da177e4 1202
a9913044 1203 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
1204 be mounted
1205 Format: <1-256>
1206
1207 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1208 should make use of. maxcpus=n : n >= 0 limits the
1209 kernel to using 'n' processors. n=0 is a special case,
1210 it is equivalent to "nosmp", which also disables
1211 the IO APIC.
1da177e4 1212
2b2c3750
BP
1213 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1214 equal to this physical address is ignored.
1215
a9913044 1216 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1217 Should be between 1 and 2^32-1.
1218
1219 max_report_luns=
a9913044 1220 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1221 Should be between 1 and 16384.
1222
1da177e4
LT
1223 mcatest= [IA-64]
1224
cd4f0ef7 1225 mce [X86-32] Machine Check Exception
1da177e4 1226
71cced6e 1227 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1228
1da177e4
LT
1229 md= [HW] RAID subsystems devices and level
1230 See Documentation/md.txt.
a9913044 1231
1da177e4
LT
1232 mdacon= [MDA]
1233 Format: <first>,<last>
1234 Specifies range of consoles to be captured by the MDA.
a9913044 1235
1da177e4
LT
1236 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1237 Amount of memory to be used when the kernel is not able
1238 to see the whole system memory or for test.
cd4f0ef7 1239 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1240 address space collisions. Without memmap= PCI devices
1241 could be placed at addresses belonging to unused RAM.
1242
cd4f0ef7 1243 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1244 memory.
1245
6902aa84
PM
1246 memchunk=nn[KMG]
1247 [KNL,SH] Allow user to override the default size for
1248 per-device physically contiguous DMA buffers.
1249
cd4f0ef7 1250 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1da177e4
LT
1251 E820 memory map, as specified by the user.
1252 Such memmap=exactmap lines can be constructed based on
1253 BIOS output or other requirements. See the memmap=nn@ss
1254 option description.
1255
1256 memmap=nn[KMG]@ss[KMG]
1257 [KNL] Force usage of a specific region of memory
1258 Region of memory to be used, from ss to ss+nn.
1259
1260 memmap=nn[KMG]#ss[KMG]
1261 [KNL,ACPI] Mark specific memory as ACPI data.
1262 Region of memory to be used, from ss to ss+nn.
1263
1264 memmap=nn[KMG]$ss[KMG]
1265 [KNL,ACPI] Mark specific memory as reserved.
1266 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1267 Example: Exclude memory from 0x18690000-0x1869ffff
1268 memmap=64K$0x18690000
1269 or
1270 memmap=0x10000$0x18690000
1da177e4 1271
9f077871
JF
1272 memory_corruption_check=0/1 [X86]
1273 Some BIOSes seem to corrupt the first 64k of
1274 memory when doing things like suspend/resume.
1275 Setting this option will scan the memory
1276 looking for corruption. Enabling this will
1277 both detect corruption and prevent the kernel
1278 from using the memory being corrupted.
1279 However, its intended as a diagnostic tool; if
1280 repeatable BIOS-originated corruption always
1281 affects the same memory, you can use memmap=
1282 to prevent the kernel from using that memory.
1283
1284 memory_corruption_check_size=size [X86]
1285 By default it checks for corruption in the low
1286 64k, making this memory unavailable for normal
1287 use. Use this parameter to scan for
1288 corruption in more or less memory.
1289
1290 memory_corruption_check_period=seconds [X86]
1291 By default it checks for corruption every 60
1292 seconds. Use this parameter to check at some
1293 other rate. 0 disables periodic checking.
1294
caadbdce 1295 memtest= [KNL,X86] Enable memtest
c64df707
YL
1296 Format: <integer>
1297 range: 0,4 : pattern number
1298 default : 0 <disable>
1299
1da177e4
LT
1300 meye.*= [HW] Set MotionEye Camera parameters
1301 See Documentation/video4linux/meye.txt.
1302
8f36881b
AS
1303 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1304 Multi-Function General Purpose Timers on AMD Geode
1305 platforms.
1306
e6c4dc6c
WT
1307 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1308 the BIOS has incorrectly applied a workaround. TinyBIOS
1309 version 0.98 is known to be affected, 0.99 fixes the
1310 problem by letting the user disable the workaround.
1311
1da177e4
LT
1312 mga= [HW,DRM]
1313
6b74ab97
MG
1314 mminit_loglevel=
1315 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1316 parameter allows control of the logging verbosity for
1317 the additional memory initialisation checks. A value
1318 of 0 disables mminit logging and a level of 4 will
1319 log everything. Information is printed at KERN_DEBUG
1320 so loglevel=8 may also need to be specified.
1321
1da177e4
LT
1322 mousedev.tap_time=
1323 [MOUSE] Maximum time between finger touching and
1324 leaving touchpad surface for touch to be considered
1325 a tap and be reported as a left button click (for
1326 touchpads working in absolute mode only).
1327 Format: <msecs>
1328 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1329 reporting absolute coordinates, such as tablets
1330 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1331 reporting absolute coordinates, such as tablets
1332
1333 mpu401= [HW,OSS]
1334 Format: <io>,<irq>
1335
1336 MTD_Partition= [MTD]
1337 Format: <name>,<region-number>,<size>,<offset>
1338
a9913044
RD
1339 MTD_Region= [MTD] Format:
1340 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1341
1342 mtdparts= [MTD]
c8facbb6 1343 See drivers/mtd/cmdlinepart.c.
1da177e4 1344
9db829f4
BD
1345 mtdset= [ARM]
1346 ARM/S3C2412 JIVE boot control
1347
1348 See arch/arm/mach-s3c2412/mach-jive.c
1349
1da177e4 1350 mtouchusb.raw_coordinates=
a9913044
RD
1351 [HW] Make the MicroTouch USB driver use raw coordinates
1352 ('y', default) or cooked coordinates ('n')
1da177e4
LT
1353
1354 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1355
1356 NCR_D700= [HW,SCSI]
1357 See header of drivers/scsi/NCR_D700.c.
1358
1359 ncr5380= [HW,SCSI]
1360
1361 ncr53c400= [HW,SCSI]
1362
1363 ncr53c400a= [HW,SCSI]
1364
1365 ncr53c406a= [HW,SCSI]
1366
1367 ncr53c8xx= [HW,SCSI]
1368
1369 netdev= [NET] Network devices parameters
1370 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1371 Note that mem_start is often overloaded to mean
1372 something different and driver-specific.
a9913044
RD
1373 This usage is only documented in each driver source
1374 file if at all.
1375
58401572
KPO
1376 nf_conntrack.acct=
1377 [NETFILTER] Enable connection tracking flow accounting
1378 0 to disable accounting
1379 1 to enable accounting
1380 Default value depends on CONFIG_NF_CT_ACCT that is
1381 going to be removed in 2.6.29.
1382
1da177e4 1383 nfsaddrs= [NFS]
6ded55da 1384 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
1385
1386 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
6ded55da 1387 See Documentation/filesystems/nfsroot.txt.
1da177e4 1388
a72b4422
TM
1389 nfs.callback_tcpport=
1390 [NFS] set the TCP port on which the NFSv4 callback
1391 channel should listen.
1392
58df095b
TM
1393 nfs.idmap_cache_timeout=
1394 [NFS] set the maximum lifetime for idmapper cache
1395 entries.
1396
f43bf0be
TM
1397 nfs.enable_ino64=
1398 [NFS] enable 64-bit inode numbers.
1399 If zero, the NFS client will fake up a 32-bit inode
1400 number for the readdir() and stat() syscalls instead
1401 of returning the full 64-bit number.
1402 The default is to return 64-bit inode numbers.
1403
e7ba176b
HS
1404 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1405 when a NMI is triggered.
1406 Format: [state][,regs][,debounce][,die]
1407
cd4f0ef7 1408 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1da177e4 1409
cd4f0ef7 1410 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1411 emulation library even if a 387 maths coprocessor
1412 is present.
1413
c1aee215
CL
1414 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1415 caches in the slab allocator. Saves per-node memory,
1416 but will impact performance.
3395ee05 1417
a9913044
RD
1418 noalign [KNL,ARM]
1419
1da177e4
LT
1420 noapic [SMP,APIC] Tells the kernel to not make use of any
1421 IOAPICs that may be present in the system.
1422
1da177e4
LT
1423 nobats [PPC] Do not use BATs for mapping kernel lowmem
1424 on "Classic" PPC cores.
1425
1426 nocache [ARM]
a9913044 1427
163ecdff
SN
1428 nodelayacct [KNL] Disable per-task delay accounting
1429
1da177e4
LT
1430 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1431
6902aa84
PM
1432 nodsp [SH] Disable hardware DSP at boot time.
1433
8b2cb7a8
HY
1434 noefi [X86-32,X86-64] Disable EFI runtime services support.
1435
1da177e4
LT
1436 noexec [IA-64]
1437
cd4f0ef7 1438 noexec [X86-32,X86-64]
f5a1b191 1439 On X86-32 available only on PAE configured kernels.
1da177e4 1440 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1441 noexec=off: disable non-executable mappings
1442
1443 noexec32 [X86-64]
1444 This affects only 32-bit executables.
1445 noexec32=on: enable non-executable mappings (default)
1446 read doesn't imply executable mappings
1447 noexec32=off: disable non-executable mappings
1448 read implies executable mappings
1da177e4 1449
6902aa84
PM
1450 nofpu [SH] Disable hardware FPU at boot time.
1451
cd4f0ef7 1452 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1453 register save and restore. The kernel will only save
1454 legacy floating-point registers on task switch.
1da177e4 1455
191679fd
AK
1456 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1457
6902aa84 1458 nohlt [BUGS=ARM,SH]
a9913044 1459
cd4f0ef7 1460 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1461 instruction doesn't work correctly and not to
1462 use it.
1463
1464 nohalt [IA-64] Tells the kernel not to use the power saving
1465 function PAL_HALT_LIGHT when idle. This increases
1466 power-consumption. On the positive side, it reduces
1467 interrupt wake-up latency, which may improve performance
1468 in certain environments such as networked servers or
1469 real-time systems.
1470
79bf2bb3
TG
1471 nohz= [KNL] Boottime enable/disable dynamic ticks
1472 Valid arguments: on, off
1473 Default: on
1474
cd4f0ef7 1475 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
8542b200 1476
cd4f0ef7 1477 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1478 disable unhandled interrupt sources.
1479
cd4f0ef7 1480 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
8542b200
ZA
1481 broken timer IRQ sources.
1482
1da177e4
LT
1483 noisapnp [ISAPNP] Disables ISA PnP code.
1484
1485 noinitrd [RAM] Tells the kernel not to load any configured
1486 initial RAM disk.
1487
1488 nointroute [IA-64]
1489
0aa366f3
TL
1490 nojitter [IA64] Disables jitter checking for ITC timers.
1491
cd4f0ef7 1492 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1493
cd4f0ef7 1494 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1495
6e1cb38a
SS
1496 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1497
af9d1388
SS
1498 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1499 default x2apic cluster mode on platforms
1500 supporting x2apic.
1501
1da177e4
LT
1502 noltlbs [PPC] Do not use large page/tlb entries for kernel
1503 lowmem mapping on PPC40x.
1504
312f1f01
H
1505 nomca [IA-64] Disable machine check abort handling
1506
cd4f0ef7 1507 nomce [X86-32] Machine Check Exception
abe37e5a 1508
83d7384f
AS
1509 nomfgpt [X86-32] Disable Multi-Function General Purpose
1510 Timer usage (for AMD Geode machines).
1511
cd4f0ef7 1512 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1513
cd4f0ef7 1514 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1515 with UP alternatives
1516
1da177e4
LT
1517 noresidual [PPC] Don't use residual data on PReP machines.
1518
a9913044
RD
1519 noresume [SWSUSP] Disables resume and restores original swap
1520 space.
1521
1da177e4
LT
1522 no-scroll [VGA] Disables scrollback.
1523 This is required for the Braillex ib80-piezo Braille
1524 reader made by F.H. Papenmeier (Germany).
1525
1526 nosbagart [IA-64]
1527
cd4f0ef7 1528 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1529
61ec7567
LB
1530 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1531 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1532
97842216
DJ
1533 nosoftlockup [KNL] Disable the soft-lockup detector.
1534
1da177e4
LT
1535 nosync [HW,M68K] Disables sync negotiation for all devices.
1536
cd4f0ef7 1537 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1538
1539 nousb [USB] Disable the USB subsystem
1540
1541 nowb [ARM]
a9913044 1542
a6c75b86
FY
1543 nptcg= [IA64] Override max number of concurrent global TLB
1544 purges which is reported from either PAL_VM_SUMMARY or
1545 SAL PALO.
1546
f0c0b2b8
KH
1547 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1548 one of ['zone', 'node', 'default'] can be specified
1549 This can be set from sysctl after boot.
1550 See Documentation/sysctl/vm.txt for details.
1551
a61c2d78
DJ
1552 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1553
3ef0e1f8
AS
1554 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1555 Rather than timing out after 20 ms if an EC
1556 command is not properly ACKed, override the length
1557 of the timeout. We have interrupts disabled while
1558 waiting for the ACK, so if this is set too high
1559 interrupts *may* be lost!
1560
1da177e4
LT
1561 opl3= [HW,OSS]
1562 Format: <io>
1563
1da177e4
LT
1564 oprofile.timer= [HW]
1565 Use timer interrupt instead of performance counters
1566
1da177e4
LT
1567 osst= [HW,SCSI] SCSI Tape Driver
1568 Format: <buffer_size>,<write_threshold>
1569 See also Documentation/scsi/st.txt.
1570
1571 panic= [KNL] Kernel behaviour on panic
1572 Format: <timeout>
1573
1574 parkbd.port= [HW] Parallel port number the keyboard adapter is
1575 connected to, default is 0.
1576 Format: <parport#>
1577 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1578 0 for XT, 1 for AT (default is AT).
a9913044
RD
1579 Format: <mode>
1580
1581 parport= [HW,PPT] Specify parallel ports. 0 disables.
1582 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1583 Use 'auto' to force the driver to use any
1584 IRQ/DMA settings detected (the default is to
1585 ignore detected IRQ/DMA settings because of
1586 possible conflicts). You can specify the base
1587 address, IRQ, and DMA settings; IRQ and DMA
1588 should be numbers, or 'auto' (for using detected
1589 settings on that particular port), or 'nofifo'
1590 (to avoid using a FIFO even if it is detected).
1591 Parallel ports are assigned in the order they
1592 are specified on the command line, starting
1593 with parport0.
1594
1595 parport_init_mode= [HW,PPT]
1596 Configure VIA parallel port to operate in
1597 a specific mode. This is necessary on Pegasos
1598 computer where firmware has no options for setting
1599 up parallel port mode and sets it to spp.
1600 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1601 Format: [spp|ps2|epp|ecp|ecpepp]
1602
a9913044
RD
1603 pas2= [HW,OSS] Format:
1604 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1605
1da177e4
LT
1606 pas16= [HW,SCSI]
1607 See header of drivers/scsi/pas16.c.
1608
dd287796
AM
1609 pause_on_oops=
1610 Halt all CPUs after the first oops has been printed for
1611 the specified number of seconds. This is to be used if
1612 your oopses keep scrolling off the screen.
1613
1da177e4
LT
1614 pcbit= [HW,ISDN]
1615
1616 pcd. [PARIDE]
1617 See header of drivers/block/paride/pcd.c.
1618 See also Documentation/paride.txt.
1619
a9913044 1620 pci=option[,option...] [PCI] various PCI subsystem options:
c0115606 1621 off [X86] don't probe for the PCI bus
cd4f0ef7 1622 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1623 the hardware directly. Use this if your machine
1624 has a non-standard PCI host bridge.
cd4f0ef7 1625 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1626 hardware access methods are allowed. Use this
1627 if you experience crashes upon bootup and you
1628 suspect they are caused by the BIOS.
c0115606 1629 conf1 [X86] Force use of PCI Configuration
a9913044 1630 Mechanism 1.
c0115606 1631 conf2 [X86] Force use of PCI Configuration
a9913044 1632 Mechanism 2.
7f785763
RD
1633 noaer [PCIE] If the PCIEAER kernel config parameter is
1634 enabled, this kernel boot option can be used to
1635 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1636 nodomains [PCI] Disable support for multiple PCI
1637 root domains (aka PCI segments, in ACPI-speak).
cd4f0ef7 1638 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
61be6d66 1639 Configuration
309e57df
MW
1640 nomsi [MSI] If the PCI_MSI kernel config parameter is
1641 enabled, this kernel boot option can be used to
1642 disable the use of MSI interrupts system-wide.
cd4f0ef7 1643 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1644 routing table. These calls are known to be buggy
1645 on several machines and they hang the machine
1646 when used, but on other computers it's the only
1647 way to get the interrupt routing table. Try
1648 this option if the kernel is unable to allocate
1649 IRQs or discover secondary PCI buses on your
1650 motherboard.
c0115606 1651 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1652 Use with caution as certain devices share
1653 address decoders between ROMs and other
1654 resources.
c0115606 1655 norom [X86] Do not assign address space to
bb71ad88
GH
1656 expansion ROMs that do not already have
1657 BIOS assigned address ranges.
c0115606 1658 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1659 assigned automatically to PCI devices. You can
1660 make the kernel exclude IRQs of your ISA cards
1661 this way.
c0115606 1662 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1663 of the PIRQ table (normally generated
1664 by the BIOS) if it is outside the
1665 F0000h-100000h range.
c0115606 1666 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1667 useful if the kernel is unable to find your
1668 secondary buses and you want to tell it
1669 explicitly which ones they are.
c0115606 1670 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1671 numbers ourselves, overriding
1672 whatever the firmware may have done.
c0115606 1673 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1674 in the BIOS $PIR table. This is needed on
1675 some systems with broken BIOSes, notably
1676 some HP Pavilion N5400 and Omnibook XE3
1677 notebooks. This will have no effect if ACPI
1678 IRQ routing is enabled.
c0115606 1679 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1680 or for PCI scanning.
c0115606 1681 use_crs [X86] Use _CRS for PCI resource
62f420f8 1682 allocation.
a9913044
RD
1683 routeirq Do IRQ routing for all PCI devices.
1684 This is normally done in pci_enable_device(),
1685 so this option is a temporary workaround
1686 for broken drivers that don't call it.
13a6ddb0
YL
1687 skip_isa_align [X86] do not align io start addr, so can
1688 handle more pci cards
a9913044
RD
1689 firmware [ARM] Do not re-enumerate the bus but instead
1690 just use the configuration from the
1691 bootloader. This is currently used on
1692 IXP2000 systems where the bus has to be
1693 configured a certain way for adjunct CPUs.
0637a70a
AK
1694 noearly [X86] Don't do any early type 1 scanning.
1695 This might help on some broken boards which
1696 machine check when some devices' config space
1697 is read. But various workarounds are disabled
1698 and some IOMMU drivers will not work.
6b4b78fe
MD
1699 bfsort Sort PCI devices into breadth-first order.
1700 This sorting is done to get a device
1701 order compatible with older (<= 2.4) kernels.
1702 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1703 cbiosize=nn[KMG] The fixed amount of bus space which is
1704 reserved for the CardBus bridge's IO window.
1705 The default value is 256 bytes.
1706 cbmemsize=nn[KMG] The fixed amount of bus space which is
1707 reserved for the CardBus bridge's memory
1708 window. The default value is 64 megabytes.
6b4b78fe 1709
e5665a45
CE
1710 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1711 Management.
1712 off Disable ASPM.
1713 force Enable ASPM even on devices that claim not to support it.
1714 WARNING: Forcing ASPM on may cause system lockups.
1715
1da177e4
LT
1716 pcmv= [HW,PCMCIA] BadgePAD 4
1717
1718 pd. [PARIDE]
1719 See Documentation/paride.txt.
1720
1721 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1722 boot time.
1723 Format: { 0 | 1 }
1724 See arch/parisc/kernel/pdc_chassis.c
1725
1726 pf. [PARIDE]
1727 See Documentation/paride.txt.
1728
1729 pg. [PARIDE]
1730 See Documentation/paride.txt.
1731
1732 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 1733 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
1734
1735 plip= [PPT,NET] Parallel port network link
1736 Format: { parport<nr> | timid | 0 }
1737 See also Documentation/parport.txt.
1738
de32a243
TG
1739 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1740 Override pmtimer IOPort with a hex value.
1741 e.g. pmtmr=0x508
1742
97ef062b
BH
1743 pnp.debug [PNP]
1744 Enable PNP debug messages. This depends on the
1745 CONFIG_PNP_DEBUG_MESSAGES option.
1746
1da177e4
LT
1747 pnpacpi= [ACPI]
1748 { off }
1749
1750 pnpbios= [ISAPNP]
1751 { on | off | curr | res | no-curr | no-res }
1752
1753 pnp_reserve_irq=
1754 [ISAPNP] Exclude IRQs for the autoconfiguration
1755
1756 pnp_reserve_dma=
1757 [ISAPNP] Exclude DMAs for the autoconfiguration
1758
1759 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1760 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1761
1762 pnp_reserve_mem=
a9913044
RD
1763 [ISAPNP] Exclude memory regions for the
1764 autoconfiguration.
1da177e4
LT
1765 Ranges are in pairs (memory base and size).
1766
346e15be
JB
1767 dynamic_printk
1768 Enables pr_debug()/dev_dbg() calls if
1769 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1770 be switched on/off via <debugfs>/dynamic_printk/modules
1771
45807a1d
IM
1772 print-fatal-signals=
1773 [KNL] debug: print fatal signals
1774 print-fatal-signals=1: print segfault info to
1775 the kernel console.
1776 default: off.
1777
e84845c4
RD
1778 printk.time= Show timing data prefixed to each printk message line
1779 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1780
1da177e4 1781 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1782 Format: [schedule,]<number>
1783 Param: "schedule" - profile schedule points.
1784 Param: <number> - step/bucket size as a power of 2 for
1785 statistical time based profiling.
b3da2a73
MG
1786 Param: "sleep" - profile D-state sleeping (millisecs).
1787 Requires CONFIG_SCHEDSTATS
c0fe2e69 1788 Param: "kvm" - profile VM exits.
1da177e4 1789
a9913044 1790 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1791 Limit processor to maximum C-state
1792 max_cstate=9 overrides any DMI blacklist limit.
1793
41c0d868
LB
1794 processor.nocst [HW,ACPI]
1795 Ignore the _CST method to determine C-states,
1796 instead using the legacy FADT method
1797
1da177e4
LT
1798 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1799 before loading.
1800 See Documentation/ramdisk.txt.
1801
a9913044
RD
1802 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1803 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1804 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1805 per second.
a9913044
RD
1806 psmouse.resetafter= [HW,MOUSE]
1807 Try to reset the device after so many bad packets
1da177e4
LT
1808 (0 = never).
1809 psmouse.resolution=
1810 [HW,MOUSE] Set desired mouse resolution, in dpi.
1811 psmouse.smartscroll=
a9913044 1812 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1813 0 = disabled, 1 = enabled (default).
1814
1815 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1816 Format:
1817 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1818
1819 pt. [PARIDE]
1820 See Documentation/paride.txt.
1821
dc8c8587
KS
1822 pty.legacy_count=
1823 [KNL] Number of legacy pty's. Overwrites compiled-in
1824 default number.
1825
7d2c502f 1826 quiet [KNL] Disable most log messages
a9913044 1827
1da177e4
LT
1828 r128= [HW,DRM]
1829
1830 raid= [HW,RAID]
1831 See Documentation/md.txt.
1832
a9913044 1833 ramdisk_blocksize= [RAM]
1da177e4 1834 See Documentation/ramdisk.txt.
a9913044 1835
1da177e4 1836 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1da177e4
LT
1837 See Documentation/ramdisk.txt.
1838
24aaef8d
RD
1839 rcupdate.blimit= [KNL,BOOT]
1840 Set maximum number of finished RCU callbacks to process
1841 in one batch.
21a1ea9e 1842
24aaef8d
RD
1843 rcupdate.qhimark= [KNL,BOOT]
1844 Set threshold of queued
21a1ea9e
DS
1845 RCU callbacks over which batch limiting is disabled.
1846
24aaef8d
RD
1847 rcupdate.qlowmark= [KNL,BOOT]
1848 Set threshold of queued RCU callbacks below which
1849 batch limiting is re-enabled.
21a1ea9e 1850
ffdfc409
OJ
1851 rdinit= [KNL]
1852 Format: <full_path>
1853 Run specified binary instead of /init from the ramdisk,
1854 used for early userspace startup. See initrd.
1855
cd4f0ef7 1856 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1857 Format: <reboot_mode>[,<reboot_mode2>[,...]]
e53dd083 1858 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 1859
46b6d94e
PJ
1860 relax_domain_level=
1861 [KNL, SMP] Set scheduler's default relax_domain_level.
1862 See Documentation/cpusets.txt.
1863
1da177e4
LT
1864 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1865
cd4f0ef7 1866 reservetop= [X86-32]
461a9aff
ZA
1867 Format: nn[KMG]
1868 Reserves a hole at the top of the kernel virtual
1869 address space.
1870
7e96287d
VG
1871 reset_devices [KNL] Force drivers to reset the underlying device
1872 during initialization.
1873
a9913044
RD
1874 resume= [SWSUSP]
1875 Specify the partition device for software suspend
1da177e4 1876
ecbd0da1
RW
1877 resume_offset= [SWSUSP]
1878 Specify the offset from the beginning of the partition
1879 given by "resume=" at which the swap header is located,
1880 in <PAGE_SIZE> units (needed only for swap files).
1881 See Documentation/power/swsusp-and-swap-files.txt
1882
0a7b35cb
MN
1883 retain_initrd [RAM] Keep initrd memory after extraction
1884
1da177e4
LT
1885 rhash_entries= [KNL,NET]
1886 Set number of hash buckets for route cache
1887
1888 riscom8= [HW,SERIAL]
1889 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1890
1891 ro [KNL] Mount root device read-only on boot
1892
1893 root= [KNL] Root filesystem
1894
1895 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1896 mount the root filesystem
1897
1898 rootflags= [KNL] Set root filesystem mount option string
1899
1900 rootfstype= [KNL] Set root filesystem type
1901
cc1ed754
PO
1902 rootwait [KNL] Wait (indefinitely) for root device to show up.
1903 Useful for devices that are detected asynchronously
1904 (e.g. USB and MMC devices).
1905
20510f2f
JM
1906 root_plug.vendor_id=
1907 [ROOTPLUG] Override the default vendor ID
1908
1909 root_plug.product_id=
1910 [ROOTPLUG] Override the default product ID
1911
1912 root_plug.debug=
1913 [ROOTPLUG] Enable debugging output
1914
1da177e4
LT
1915 rw [KNL] Mount root device read-write on boot
1916
1917 S [KNL] Run init in single mode
1918
1919 sa1100ir [NET]
1920 See drivers/net/irda/sa1100_ir.c.
1921
1da177e4 1922 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1923
1da177e4
LT
1924 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1925 Format: <io>[,<timeout>[,<isapnp>]]
1926
1927 scsi_debug_*= [SCSI]
1928 See drivers/scsi/scsi_debug.c.
1929
1930 scsi_default_dev_flags=
1931 [SCSI] SCSI default device flags
1932 Format: <integer>
1933
1934 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1935 Format: <vendor>:<model>:<flags>
1936 (flags are integer value)
1937
6af6632a
RD
1938 scsi_logging_level= [SCSI] a bit mask of logging levels
1939 See drivers/scsi/scsi_logging.h for bits. Also
1940 settable via sysctl at dev.scsi.logging_level
1941 (/proc/sys/dev/scsi/logging_level).
1942 There is also a nice 'scsi_logging_level' script in the
1943 S390-tools package, available for download at
1944 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 1945
3e082a91
MW
1946 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1947 discovered. async scans them in kernel threads,
1948 allowing boot to proceed. none ignores them, expecting
1949 user space to do the scan.
1950
1da177e4
LT
1951 selinux [SELINUX] Disable or enable SELinux at boot time.
1952 Format: { "0" | "1" }
1953 See security/selinux/Kconfig help text.
1954 0 -- disable.
1955 1 -- enable.
1956 Default value is set via kernel config option.
1957 If enabled at boot time, /selinux/disable can be used
1958 later to disable prior to initial policy load.
1959
4e5ab4cb
JM
1960 selinux_compat_net =
1961 [SELINUX] Set initial selinux_compat_net flag value.
e53dd083
MCC
1962 Format: { "0" | "1" }
1963 0 -- use new secmark-based packet controls
1964 1 -- use legacy packet controls
1965 Default value is 0 (preferred).
1966 Value can be changed at runtime via
1967 /selinux/compat_net.
4e5ab4cb 1968
cd4f0ef7 1969 serialnumber [BUGS=X86-32]
1da177e4 1970
1da177e4
LT
1971 shapers= [NET]
1972 Maximal number of shapers.
a9913044 1973
b05f78f5
YL
1974 show_msr= [x86] show boot-time MSR settings
1975 Format: { <integer> }
1976 Show boot-time (BIOS-initialized) MSR settings.
1977 The parameter means the number of CPUs to show,
1978 for example 1 means boot CPU only.
1979
1da177e4
LT
1980 sim710= [SCSI,HW]
1981 See header of drivers/scsi/sim710.c.
1982
1983 simeth= [IA-64]
1984 simscsi=
a9913044 1985
1da177e4
LT
1986 slram= [HW,MTD]
1987
f0630fff
CL
1988 slub_debug[=options[,slabs]] [MM, SLUB]
1989 Enabling slub_debug allows one to determine the
1990 culprit if slab objects become corrupted. Enabling
1991 slub_debug can create guard zones around objects and
1992 may poison objects when not in use. Also tracks the
1993 last alloc / free. For more information see
1994 Documentation/vm/slub.txt.
c1aee215
CL
1995
1996 slub_max_order= [MM, SLUB]
f0630fff
CL
1997 Determines the maximum allowed order for slabs.
1998 A high setting may cause OOMs due to memory
1999 fragmentation. For more information see
2000 Documentation/vm/slub.txt.
c1aee215
CL
2001
2002 slub_min_objects= [MM, SLUB]
f0630fff
CL
2003 The minimum number of objects per slab. SLUB will
2004 increase the slab order up to slub_max_order to
2005 generate a sufficiently large slab able to contain
2006 the number of objects indicated. The higher the number
2007 of objects the smaller the overhead of tracking slabs
2008 and the less frequently locks need to be acquired.
c1aee215
CL
2009 For more information see Documentation/vm/slub.txt.
2010
2011 slub_min_order= [MM, SLUB]
2012 Determines the mininum page order for slabs. Must be
f0630fff 2013 lower than slub_max_order.
c1aee215
CL
2014 For more information see Documentation/vm/slub.txt.
2015
2016 slub_nomerge [MM, SLUB]
f0630fff 2017 Disable merging of slabs with similar size. May be
c1aee215 2018 necessary if there is some reason to distinguish
f0630fff
CL
2019 allocs to different slabs. Debug options disable
2020 merging on their own.
c1aee215
CL
2021 For more information see Documentation/vm/slub.txt.
2022
1da177e4
LT
2023 smart2= [HW]
2024 Format: <io1>[,<io2>[,...,<io8>]]
2025
cd4f0ef7 2026 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2027 attempt to substitute SMP alternatives once at boot.
2028
d0d4f69b
BH
2029 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2030 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2031 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2032 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2033 smsc-ircc2.ircc_irq= [HW] IRQ line
2034 smsc-ircc2.ircc_dma= [HW] DMA channel
2035 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2036 0: Toshiba Satellite 1800 (GP data pin select)
2037 1: Fast pin select (default)
2038 2: ATC IRMode
2039
1da177e4
LT
2040 snd-ad1816a= [HW,ALSA]
2041
2042 snd-ad1848= [HW,ALSA]
2043
2044 snd-ali5451= [HW,ALSA]
2045
2046 snd-als100= [HW,ALSA]
2047
2048 snd-als4000= [HW,ALSA]
2049
2050 snd-azt2320= [HW,ALSA]
2051
2052 snd-cmi8330= [HW,ALSA]
2053
2054 snd-cmipci= [HW,ALSA]
2055
2056 snd-cs4231= [HW,ALSA]
2057
2058 snd-cs4232= [HW,ALSA]
2059
2060 snd-cs4236= [HW,ALSA]
2061
2062 snd-cs4281= [HW,ALSA]
2063
2064 snd-cs46xx= [HW,ALSA]
2065
2066 snd-dt019x= [HW,ALSA]
2067
2068 snd-dummy= [HW,ALSA]
2069
2070 snd-emu10k1= [HW,ALSA]
2071
2072 snd-ens1370= [HW,ALSA]
2073
2074 snd-ens1371= [HW,ALSA]
2075
2076 snd-es968= [HW,ALSA]
2077
2078 snd-es1688= [HW,ALSA]
2079
2080 snd-es18xx= [HW,ALSA]
2081
2082 snd-es1938= [HW,ALSA]
2083
2084 snd-es1968= [HW,ALSA]
2085
2086 snd-fm801= [HW,ALSA]
2087
2088 snd-gusclassic= [HW,ALSA]
2089
2090 snd-gusextreme= [HW,ALSA]
2091
2092 snd-gusmax= [HW,ALSA]
2093
2094 snd-hdsp= [HW,ALSA]
2095
2096 snd-ice1712= [HW,ALSA]
2097
2098 snd-intel8x0= [HW,ALSA]
2099
2100 snd-interwave= [HW,ALSA]
2101
2102 snd-interwave-stb=
2103 [HW,ALSA]
2104
2105 snd-korg1212= [HW,ALSA]
2106
2107 snd-maestro3= [HW,ALSA]
2108
2109 snd-mpu401= [HW,ALSA]
2110
2111 snd-mtpav= [HW,ALSA]
2112
2113 snd-nm256= [HW,ALSA]
2114
2115 snd-opl3sa2= [HW,ALSA]
2116
2117 snd-opti92x-ad1848=
2118 [HW,ALSA]
2119
2120 snd-opti92x-cs4231=
2121 [HW,ALSA]
2122
2123 snd-opti93x= [HW,ALSA]
2124
2125 snd-pmac= [HW,ALSA]
2126
2127 snd-rme32= [HW,ALSA]
2128
2129 snd-rme96= [HW,ALSA]
2130
2131 snd-rme9652= [HW,ALSA]
2132
2133 snd-sb8= [HW,ALSA]
2134
2135 snd-sb16= [HW,ALSA]
2136
2137 snd-sbawe= [HW,ALSA]
2138
2139 snd-serial= [HW,ALSA]
2140
2141 snd-sgalaxy= [HW,ALSA]
2142
2143 snd-sonicvibes= [HW,ALSA]
2144
2145 snd-sun-amd7930=
2146 [HW,ALSA]
2147
2148 snd-sun-cs4231= [HW,ALSA]
2149
2150 snd-trident= [HW,ALSA]
2151
2152 snd-usb-audio= [HW,ALSA,USB]
2153
2154 snd-via82xx= [HW,ALSA]
2155
2156 snd-virmidi= [HW,ALSA]
2157
2158 snd-wavefront= [HW,ALSA]
2159
2160 snd-ymfpci= [HW,ALSA]
a9913044 2161
9c44bc03
IM
2162 softlockup_panic=
2163 [KNL] Should the soft-lockup detector generate panics.
2164
1da177e4
LT
2165 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2166 See Documentation/sonypi.txt
2167
2168 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2169 See Documentation/specialix.txt.
2170
2171 spia_io_base= [HW,MTD]
2172 spia_fio_base=
2173 spia_pedr=
2174 spia_peddr=
2175
2176 sscape= [HW,OSS]
2177 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2178
1da177e4
LT
2179 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2180 See Documentation/scsi/st.txt.
2181
1da177e4
LT
2182 sti= [PARISC,HW]
2183 Format: <num>
2184 Set the STI (builtin display/keyboard on the HP-PARISC
2185 machines) console (graphic card) which should be used
2186 as the initial boot-console.
2187 See also comment in drivers/video/console/sticore.c.
2188
2189 sti_font= [HW]
2190 See comment in drivers/video/console/sticore.c.
2191
2192 stifb= [HW]
2193 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2194
42a7fc4a
GB
2195 sunrpc.pool_mode=
2196 [NFS]
2197 Control how the NFS server code allocates CPUs to
2198 service thread pools. Depending on how many NICs
2199 you have and where their interrupts are bound, this
2200 option will affect which CPUs will do NFS serving.
2201 Note: this parameter cannot be changed while the
2202 NFS server is running.
2203
2204 auto the server chooses an appropriate mode
2205 automatically using heuristics
2206 global a single global pool contains all CPUs
2207 percpu one pool for each CPU
2208 pernode one pool for each NUMA node (equivalent
2209 to global on non-NUMA machines)
2210
1da177e4 2211 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2212
1da177e4
LT
2213 switches= [HW,M68k]
2214
2215 sym53c416= [HW,SCSI]
2216 See header of drivers/scsi/sym53c416.c.
2217
5d6f647f
IM
2218 sysrq_always_enabled
2219 [KNL]
2220 Ignore sysrq setting - this boot parameter will
2221 neutralize any effect of /proc/sys/kernel/sysrq.
2222 Useful for debugging.
2223
1da177e4
LT
2224 t128= [HW,SCSI]
2225 See header of drivers/scsi/t128.c.
2226
2227 tdfx= [HW,DRM]
2228
77437fd4
DB
2229 test_suspend= [SUSPEND]
2230 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2231 standby suspend) as the system sleep state to briefly
2232 enter during system startup. The system is woken from
2233 this state using a wakeup-capable RTC alarm.
2234
1da177e4
LT
2235 thash_entries= [KNL,NET]
2236 Set number of hash buckets for TCP connection
2237
f8707ec9
LB
2238 thermal.act= [HW,ACPI]
2239 -1: disable all active trip points in all thermal zones
2240 <degrees C>: override all lowest active trip points
2241
c52a7419
LB
2242 thermal.crt= [HW,ACPI]
2243 -1: disable all critical trip points in all thermal zones
22a94d79 2244 <degrees C>: override all critical trip points
c52a7419 2245
f5487145
LB
2246 thermal.nocrt= [HW,ACPI]
2247 Set to disable actions on ACPI thermal zone
2248 critical and hot trip points.
2249
72b33ef8
LB
2250 thermal.off= [HW,ACPI]
2251 1: disable ACPI thermal control
2252
a70cdc52
LB
2253 thermal.psv= [HW,ACPI]
2254 -1: disable all passive trip points
2255 <degrees C>: override all passive trip points to this value
2256
730ff34d
LB
2257 thermal.tzp= [HW,ACPI]
2258 Specify global default ACPI thermal zone polling rate
2259 <deci-seconds>: poll all this frequency
2260 0: no polling (default)
2261
1da177e4
LT
2262 tmscsim= [HW,SCSI]
2263 See comment before function dc390_setup() in
2264 drivers/scsi/tmscsim.c.
2265
2266 tp720= [HW,PS2]
2267
2268 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2269 Format:
2270 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2271
a9913044
RD
2272 turbografx.map[2|3]= [HW,JOY]
2273 TurboGraFX parallel port interface
2274 Format:
2275 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2276 See also Documentation/input/joystick-parport.txt
2277
2278 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2279 See header of drivers/scsi/u14-34f.c.
2280
2281 uart401= [HW,OSS]
2282 Format: <io>,<irq>
2283
2284 uart6850= [HW,OSS]
2285 Format: <io>,<irq>
2286
5f8364b7
AS
2287 uhci-hcd.ignore_oc=
2288 [USB] Ignore overcurrent events (default N).
2289 Some badly-designed motherboards generate lots of
2290 bogus events, for ports that aren't wired to
2291 anything. Set this parameter to avoid log spamming.
2292 Note that genuine overcurrent events won't be
2293 reported either.
2294
e3a61b0a
SA
2295 unknown_nmi_panic
2296 [X86-32,X86-64]
2297 Set unknown_nmi_panic=1 early on boot.
2298
b5e795f8
AS
2299 usbcore.autosuspend=
2300 [USB] The autosuspend time delay (in seconds) used
2301 for newly-detected USB devices (default 2). This
2302 is the time required before an idle device will be
2303 autosuspended. Devices for which the delay is set
eaafbc3a 2304 to a negative value won't be autosuspended at all.
b5e795f8 2305
fd7c519d
JK
2306 usbcore.usbfs_snoop=
2307 [USB] Set to log all usbfs traffic (default 0 = off).
2308
2309 usbcore.blinkenlights=
2310 [USB] Set to cycle leds on hubs (default 0 = off).
2311
2312 usbcore.old_scheme_first=
2313 [USB] Start with the old device initialization
2314 scheme (default 0 = off).
2315
2316 usbcore.use_both_schemes=
2317 [USB] Try the other device initialization scheme
2318 if the first one fails (default 1 = enabled).
2319
2320 usbcore.initial_descriptor_timeout=
2321 [USB] Specifies timeout for the initial 64-byte
2322 USB_REQ_GET_DESCRIPTOR request in milliseconds
2323 (default 5000 = 5.0 seconds).
2324
1da177e4
LT
2325 usbhid.mousepoll=
2326 [USBHID] The interval which mice are to be polled at.
a9913044 2327
200001eb
PJ
2328 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2329 kernel's map of available physical RAM.
2330
cd4f0ef7 2331 vdso= [X86-32,SH,x86-64]
1dbf527c 2332 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2333 vdso=1: enable VDSO (default)
2334 vdso=0: disable VDSO mapping
2335
af65d648
RM
2336 vdso32= [X86-32,X86-64]
2337 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2338 vdso32=1: enable 32-bit VDSO (default)
2339 vdso32=0: disable 32-bit VDSO mapping
2340
d080d397
YI
2341 vector= [IA-64,SMP]
2342 vector=percpu: enable percpu vector domain
2343
1da177e4
LT
2344 video= [FB] Frame buffer configuration
2345 See Documentation/fb/modedb.txt.
2346
cd4f0ef7 2347 vga= [BOOT,X86-32] Select a particular video mode
71cced6e 2348 See Documentation/x86/i386/boot.txt and
a9913044 2349 Documentation/svga.txt.
1da177e4
LT
2350 Use vga=ask for menu.
2351 This is actually a boot loader parameter; the value is
2352 passed to the kernel using a special protocol.
2353
a9913044 2354 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2355 size of <nn>. This can be used to increase the
2356 minimum size (128MB on x86). It can also be used to
2357 decrease the size and leave more room for directly
2358 mapped kernel RAM.
2359
585c3047
PO
2360 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2361 Format: <command>
1da177e4 2362
585c3047
PO
2363 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2364 Format: <command>
2365
2366 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2367 Format: <command>
a9913044 2368
1da177e4
LT
2369 waveartist= [HW,OSS]
2370 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2371
1da177e4
LT
2372 wd33c93= [HW,SCSI]
2373 See header of drivers/scsi/wd33c93.c.
2374
2375 wd7000= [HW,SCSI]
2376 See header of drivers/scsi/wd7000.c.
2377
2378 wdt= [WDT] Watchdog
8dfe9c21 2379 See Documentation/watchdog/wdt.txt.
1da177e4
LT
2380
2381 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2382 xd_geo= See header of drivers/block/xd.c.
2383
2384 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2385 Format:
2386 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2387
a62eaf15
AK
2388 norandmaps Don't use address space randomization
2389 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2390
a9913044 2391______________________________________________________________________
1da177e4
LT
2392
2393TODO:
2394
2395 Add documentation for ALSA options.
2396 Add more DRM drivers.
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