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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
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201 acpi_backlight= [HW,ACPI]
202 acpi_backlight=vendor
203 acpi_backlight=video
204 If set to vendor, prefer vendor specific driver
205 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
206 of the ACPI video.ko driver.
207
208 acpi_display_output= [HW,ACPI]
209 acpi_display_output=vendor
210 acpi_display_output=video
211 See above.
212
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213 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
214 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 215 Format: <int>
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216 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
217 debug output. Bits in debug_layer correspond to a
218 _COMPONENT in an ACPI source file, e.g.,
219 #define _COMPONENT ACPI_PCI_COMPONENT
220 Bits in debug_level correspond to a level in
221 ACPI_DEBUG_PRINT statements, e.g.,
222 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
223 See Documentation/acpi/debug.txt for more information
224 about debug layers and levels.
225
226 Enable AML "Debug" output, i.e., stores to the Debug
227 object while interpreting AML:
228 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
229 Enable PCI/PCI interrupt routing info messages:
230 acpi.debug_layer=0x400000 acpi.debug_level=0x4
231 Enable all messages related to ACPI hardware:
232 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
233
234 Some values produce so much output that the system is
235 unusable. The "log_buf_len" parameter may be useful
236 if you need to capture more output.
f989106c 237
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238 acpi.power_nocheck= [HW,ACPI]
239 Format: 1/0 enable/disable the check of power state.
240 On some bogus BIOS the _PSC object/_STA object of
241 power resource can't return the correct device power
242 state. In such case it is unneccessary to check its
243 power state again in power transition.
244 1 : disable the power state check
245
cd4f0ef7 246 acpi_pm_good [X86-32,X86-64]
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247 Override the pmtimer bug detection: force the kernel
248 to assume that this machine's pmtimer latches its value
249 and always returns good values.
250
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251 agp= [AGP]
252 { off | try_unsupported }
253 off: disable AGP support
254 try_unsupported: try to drive unsupported chipsets
255 (may crash computer or cause data corruption)
256
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257 enable_timer_pin_1 [i386,x86-64]
258 Enable PIN 1 of APIC timer
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259 Can be useful to work around chipset bugs
260 (in particular on some ATI chipsets).
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261 The kernel tries to set a reasonable default.
262
263 disable_timer_pin_1 [i386,x86-64]
264 Disable PIN 1 of APIC timer
265 Can be useful to work around chipset bugs.
266
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267 ad1848= [HW,OSS]
268 Format: <io>,<irq>,<dma>,<dma2>,<type>
269
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270 advansys= [HW,SCSI]
271 See header of drivers/scsi/advansys.c.
272
273 advwdt= [HW,WDT] Advantech WDT
274 Format: <iostart>,<iostop>
275
276 aedsp16= [HW,OSS] Audio Excel DSP 16
277 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
278 See also header of sound/oss/aedsp16.c.
a9913044 279
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280 aha152x= [HW,SCSI]
281 See Documentation/scsi/aha152x.txt.
282
283 aha1542= [HW,SCSI]
284 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
285
286 aic7xxx= [HW,SCSI]
287 See Documentation/scsi/aic7xxx.txt.
288
289 aic79xx= [HW,SCSI]
290 See Documentation/scsi/aic79xx.txt.
291
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292 amd_iommu= [HW,X86-84]
293 Pass parameters to the AMD IOMMU driver in the system.
294 Possible values are:
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295 isolate - enable device isolation (each device, as far
296 as possible, will get its own protection
297 domain)
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298 fullflush - enable flushing of IO/TLB entries when
299 they are unmapped. Otherwise they are
300 flushed before they will be reused, which
301 is a lot of faster
302
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303 amd_iommu_size= [HW,X86-64]
304 Define the size of the aperture for the AMD IOMMU
305 driver. Possible values are:
306 '32M', '64M' (default), '128M', '256M', '512M', '1G'
307
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308 amijoy.map= [HW,JOY] Amiga joystick support
309 Map of devices attached to JOY0DAT and JOY1DAT
310 Format: <a>,<b>
311 See also Documentation/kernel/input/joystick.txt
312
313 analog.map= [HW,JOY] Analog joystick and gamepad support
314 Specifies type or capabilities of an analog joystick
315 connected to one of 16 gameports
316 Format: <type1>,<type2>,..<type16>
317
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318 apc= [HW,SPARC]
319 Power management functions (SPARCstation-4/5 + deriv.)
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320 Format: noidle
321 Disable APC CPU standby support. SPARCstation-Fox does
322 not play well with APC CPU idle - disable it if you have
323 APC and your system crashes randomly.
324
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325 apic= [APIC,i386] Advanced Programmable Interrupt Controller
326 Change the output verbosity whilst booting
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327 Format: { quiet (default) | verbose | debug }
328 Change the amount of debugging information output
329 when initialising the APIC and IO-APIC components.
a9913044 330
1da177e4 331 apm= [APM] Advanced Power Management
71f77055 332 See header of arch/x86/kernel/apm_32.c.
1da177e4 333
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334 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
335 Format: <io>,<irq>,<nodeID>
336
337 ataflop= [HW,M68k]
338
339 atarimouse= [HW,MOUSE] Atari Mouse
340
341 atascsi= [HW,SCSI] Atari SCSI
342
343 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
344 EzKey and similar keyboards
345
346 atkbd.reset= [HW] Reset keyboard during initialization
347
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348 atkbd.set= [HW] Select keyboard code set
349 Format: <int> (2 = AT (default), 3 = PS/2)
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350
351 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
352 keyboards
353
354 atkbd.softraw= [HW] Choose between synthetic and real raw mode
355 Format: <bool> (0 = real, 1 = synthetic (default))
a9913044
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356
357 atkbd.softrepeat= [HW]
358 Use software keyboard repeat
1da177e4
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359
360 autotest [IA64]
361
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362 baycom_epp= [HW,AX25]
363 Format: <io>,<mode>
a9913044 364
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365 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
366 Format: <io>,<mode>
367 See header of drivers/net/hamradio/baycom_par.c.
368
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369 baycom_ser_fdx= [HW,AX25]
370 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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371 Format: <io>,<irq>,<mode>[,<baud>]
372 See header of drivers/net/hamradio/baycom_ser_fdx.c.
373
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374 baycom_ser_hdx= [HW,AX25]
375 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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376 Format: <io>,<irq>,<mode>
377 See header of drivers/net/hamradio/baycom_ser_hdx.c.
378
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379 boot_delay= Milliseconds to delay each printk during boot.
380 Values larger than 10 seconds (10000) are changed to
381 no delay (0).
382 Format: integer
383
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384 bootmem_debug [KNL] Enable bootmem allocator debug messages.
385
1da177e4 386 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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387 bttv.radio= Most important insmod options are available as
388 kernel args too.
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389 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
390 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
391
392 BusLogic= [HW,SCSI]
393 See drivers/scsi/BusLogic.c, comment before function
394 BusLogic_ParseDriverOptions().
395
396 c101= [NET] Moxa C101 synchronous serial card
397
cd4f0ef7 398 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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399 Sometimes CPU hardware bugs make them report the cache
400 size incorrectly. The kernel will attempt work arounds
401 to fix known problems, but for some CPUs it is not
402 possible to determine what the correct size should be.
403 This option provides an override for these situations.
404
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405 security= [SECURITY] Choose a security module to enable at boot.
406 If this boot parameter is not specified, only the first
407 security module asking for security registration will be
408 loaded. An invalid security module name will be treated
409 as if no module has been chosen.
410
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411 capability.disable=
412 [SECURITY] Disable capabilities. This would normally
413 be used only if an alternative security model is to be
414 configured. Potentially dangerous and should only be
415 used if you are entirely sure of the consequences.
416
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417 ccw_timeout_log [S390]
418 See Documentation/s390/CommonIO for details.
1da177e4 419
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420 cgroup_disable= [KNL] Disable a particular controller
421 Format: {name of the controller(s) to disable}
422 {Currently supported controllers - "memory"}
423
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424 checkreqprot [SELINUX] Set initial checkreqprot flag value.
425 Format: { "0" | "1" }
426 See security/selinux/Kconfig help text.
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427 0 -- check protection applied by kernel (includes
428 any implied execute protection).
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429 1 -- check protection requested by application.
430 Default value is set via a kernel config option.
a9913044
RD
431 Value can be changed at runtime via
432 /selinux/checkreqprot.
433
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SO
434 cio_ignore= [S390]
435 See Documentation/s390/CommonIO for details.
436
cd4f0ef7 437 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 438 [Deprecated]
3f6dee9b 439 Forces specified clocksource (if available) to be used
734efb46 440 when calculating gettimeofday(). If specified
3f6dee9b 441 clocksource is not available, it defaults to PIT.
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LT
442 Format: { pit | tsc | cyclone | pmtmr }
443
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444 clocksource= [GENERIC_TIME] Override the default clocksource
445 Format: <string>
446 Override the default clocksource and use the clocksource
447 with the name specified.
448 Some clocksource names to choose from, depending on
449 the platform:
450 [all] jiffies (this is the base, fallback clocksource)
451 [ACPI] acpi_pm
452 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
453 pxa_timer,timer3,32k_counter,timer0_1
454 [AVR32] avr32
cd4f0ef7 455 [X86-32] pit,hpet,tsc,vmi-timer;
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RD
456 scx200_hrt on Geode; cyclone on IBM x440
457 [MIPS] MIPS
458 [PARISC] cr16
459 [S390] tod
460 [SH] SuperH
461 [SPARC64] tick
462 [X86-64] hpet,tsc
463
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464 clearcpuid=BITNUM [X86]
465 Disable CPUID feature X for the kernel. See
466 include/asm-x86/cpufeature.h for the valid bit numbers.
467 Note the Linux specific bits are not necessarily
468 stable over kernel options, but the vendor specific
469 ones should be.
470 Also note that user programs calling CPUID directly
471 or using the feature without checking anything
472 will still see it. This just prevents it from
473 being used by the kernel or shown in /proc/cpuinfo.
474 Also note the kernel might malfunction if you disable
475 some critical bits.
476
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AV
477 code_bytes [IA32/X86_64] How many bytes of object code to print
478 in an oops report.
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CE
479 Range: 0 - 8192
480 Default: 64
481
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TG
482 hpet= [X86-32,HPET] option to control HPET usage
483 Format: { enable (default) | disable | force }
484 disable: disable HPET and use PIT instead
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CC
485 force: allow force enabled of undocumented chips (ICH4,
486 VIA, nVidia)
1da177e4 487
1da177e4 488 com20020= [HW,NET] ARCnet - COM20020 chipset
a9913044
RD
489 Format:
490 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
1da177e4
LT
491
492 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
493 Format: <io>[,<irq>]
494
a9913044
RD
495 com90xx= [HW,NET]
496 ARCnet - COM90xx chipset (memory-mapped buffers)
1da177e4
LT
497 Format: <io>[,<irq>[,<memstart>]]
498
499 condev= [HW,S390] console device
500 conmode=
a9913044 501
1da177e4
LT
502 console= [KNL] Output console device and options.
503
504 tty<n> Use the virtual console device <n>.
505
506 ttyS<n>[,options]
f1a1c2dc 507 ttyUSB0[,options]
1da177e4 508 Use the specified serial port. The options are of
f1a1c2dc
RD
509 the form "bbbbpnf", where "bbbb" is the baud rate,
510 "p" is parity ("n", "o", or "e"), "n" is number of
511 bits, and "f" is flow control ("r" for RTS or
512 omit it). Default is "9600n8".
513
514 See Documentation/serial-console.txt for more
515 information. See
516 Documentation/networking/netconsole.txt for an
517 alternative.
1da177e4 518
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YL
519 uart[8250],io,<addr>[,options]
520 uart[8250],mmio,<addr>[,options]
1da177e4
LT
521 Start an early, polled-mode console on the 8250/16550
522 UART at the specified I/O port or MMIO address,
523 switching to the matching ttyS device later. The
524 options are the same as for ttyS, above.
525
f7511d5f
ST
526 If the device connected to the port is not a TTY but a braille
527 device, prepend "brl," before the device type, for instance
528 console=brl,ttyS0
529 For now, only VisioBraille is supported.
530
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YL
531 earlycon= [KNL] Output early console device and options.
532 uart[8250],io,<addr>[,options]
533 uart[8250],mmio,<addr>[,options]
534 Start an early, polled-mode console on the 8250/16550
535 UART at the specified I/O port or MMIO address.
536 The options are the same as for ttyS, above.
537
8f4ce8c3
AS
538 no_console_suspend
539 [HW] Never suspend the console
540 Disable suspending of consoles during suspend and
541 hibernate operations. Once disabled, debugging
542 messages can reach various consoles while the rest
543 of the system is being put to sleep (ie, while
544 debugging driver suspend/resume hooks). This may
545 not work reliably with all consoles, but is known
546 to work with serial and VGA consoles.
547
1da177e4 548 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
549 Format:
550 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 551
dc009d92
EB
552 crashkernel=nn[KMG]@ss[KMG]
553 [KNL] Reserve a chunk of physical memory to
554 hold a kernel to switch to with kexec on panic.
555
fb391599
BW
556 crashkernel=range1:size1[,range2:size2,...][@offset]
557 [KNL] Same as above, but depends on the memory
558 in the running system. The syntax of range is
559 start-[end] where start and end are both
560 a memory unit (amount[KMG]). See also
561 Documentation/kdump/kdump.txt for a example.
562
1da177e4
LT
563 cs4232= [HW,OSS]
564 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
565
566 cs89x0_dma= [HW,NET]
567 Format: <dma>
568
569 cs89x0_media= [HW,NET]
570 Format: { rj45 | aui | bnc }
a9913044 571
a9913044 572 dasd= [HW,NET]
1da177e4
LT
573 See header of drivers/s390/block/dasd_devmap.c.
574
575 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
576 (one device per port)
577 Format: <port#>,<type>
578 See also Documentation/input/joystick-parport.txt
579
580 debug [KNL] Enable kernel debugging (events log level).
581
cae2ed9a
IM
582 debug_locks_verbose=
583 [KNL] verbose self-tests
584 Format=<0|1>
585 Print debugging info while doing the locking API
586 self-tests.
587 We default to 0 (no extra messages), setting it to
588 1 will print _a lot_ more information - normally
589 only useful to kernel developers.
590
3ac7fe5a
TG
591 debug_objects [KNL] Enable object debugging
592
d3af01f1
TG
593 debugpat [X86] Enable PAT debugging
594
2d27a966 595 decnet.addr= [HW,NET]
1da177e4
LT
596 Format: <area>[,<node>]
597 See also Documentation/networking/decnet.txt.
598
ecb77fa9 599 vt.default_blu= [VT]
55ff9780
AD
600 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
601 Change the default blue palette of the console.
602 This is a 16-member array composed of values
603 ranging from 0-255.
604
ecb77fa9 605 vt.default_grn= [VT]
55ff9780
AD
606 Format: <green0>,<green1>,<green2>,...,<green15>
607 Change the default green palette of the console.
608 This is a 16-member array composed of values
609 ranging from 0-255.
610
ecb77fa9 611 vt.default_red= [VT]
55ff9780
AD
612 Format: <red0>,<red1>,<red2>,...,<red15>
613 Change the default red palette of the console.
614 This is a 16-member array composed of values
615 ranging from 0-255.
616
ecb77fa9
ST
617 vt.default_utf8=
618 [VT]
55ff9780
AD
619 Format=<0|1>
620 Set system-wide default UTF-8 mode for all tty's.
ecb77fa9
ST
621 Default is 1, i.e. UTF-8 mode is enabled for all
622 newly opened terminals.
55ff9780 623
1da177e4
LT
624 dhash_entries= [KNL]
625 Set number of hash buckets for dentry cache.
a9913044 626
1da177e4
LT
627 digi= [HW,SERIAL]
628 IO parameters + enable/disable command.
629
630 digiepca= [HW,SERIAL]
631 See drivers/char/README.epca and
31c00fc1 632 Documentation/serial/digiepca.txt.
1da177e4 633
95ffa243
YL
634 disable_mtrr_cleanup [X86]
635 enable_mtrr_cleanup [X86]
636 The kernel tries to adjust MTRR layout from continuous
637 to discrete, to make X server driver able to add WB
638 entry later. This parameter enables/disables that.
639
640 mtrr_chunk_size=nn[KMG] [X86]
641 used for mtrr cleanup. It is largest continous chunk
642 that could hold holes aka. UC entries.
643
644 mtrr_gran_size=nn[KMG] [X86]
12031a62
YL
645 Used for mtrr cleanup. It is granularity of mtrr block.
646 Default is 1.
647 Large value could prevent small alignment from
648 using up MTRRs.
649
650 mtrr_spare_reg_nr=n [X86]
651 Format: <integer>
652 Range: 0,7 : spare reg number
653 Default : 1
654 Used for mtrr cleanup. It is spare mtrr entries number.
655 Set to 2 or more if your graphical card needs more.
95ffa243 656
093af8d7 657 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
658 By default the kernel will trim any uncacheable
659 memory out of your available memory pool based on
660 MTRR settings. This parameter disables that behavior,
661 possibly causing your machine to run very slowly.
662
1da177e4
LT
663 dmasound= [HW,OSS] Sound subsystem buffers
664
665 dscc4.setup= [NET]
666
667 dtc3181e= [HW,SCSI]
668
0ae53640 669 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
1da177e4
LT
670 earlyprintk=vga
671 earlyprintk=serial[,ttySn[,baudrate]]
5c05917e 672 earlyprintk=dbgp
1da177e4 673
a9913044 674 Append ",keep" to not disable it when the real console
1da177e4
LT
675 takes over.
676
5c05917e 677 Only vga or serial or usb debug port at a time.
1da177e4
LT
678
679 Currently only ttyS0 and ttyS1 are supported.
680
681 Interaction with the standard serial driver is not
682 very good.
683
684 The VGA output is eventually overwritten by the real
685 console.
686
687 eata= [HW,SCSI]
688
1da177e4 689 edd= [EDD]
8c4dd606 690 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 691
1da177e4
LT
692 eisa_irq_edge= [PARISC,HW]
693 See header of drivers/parisc/eisa.c.
694
cd4f0ef7 695 elanfreq= [X86-32]
1da177e4 696 See comment before function elanfreq_setup() in
71f77055 697 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
698
699 elevator= [IOSCHED]
16ab3adf 700 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
701 See Documentation/block/as-iosched.txt and
702 Documentation/block/deadline-iosched.txt for details.
703
e515a0d6 704 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
a9913044 705 Specifies physical address of start of kernel core
aac04b32
VG
706 image elf header. Generally kexec loader will
707 pass this option to capture kernel.
708 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
709
710 enforcing [SELINUX] Set initial enforcing status.
711 Format: {"0" | "1"}
712 See security/selinux/Kconfig help text.
713 0 -- permissive (log only, no denials).
714 1 -- enforcing (deny and log).
715 Default value is 0.
716 Value can be changed at runtime via /selinux/enforce.
717
1da177e4
LT
718 es1371= [HW,OSS]
719 Format: <spdif>,[<nomix>,[<amplifier>]]
720 See also header of sound/oss/es1371.c.
a9913044 721
1da177e4
LT
722 ether= [HW,NET] Ethernet cards parameters
723 This option is obsoleted by the "netdev=" option, which
724 has equivalent usage. See its documentation for details.
725
726 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
727 Format: <io>[,<irq>]
728
de1ba09b
AM
729 failslab=
730 fail_page_alloc=
731 fail_make_request=[KNL]
732 General fault injection mechanism.
733 Format: <interval>,<probability>,<space>,<times>
734 See also /Documentation/fault-injection/.
735
1da177e4
LT
736 fd_mcs= [HW,SCSI]
737 See header of drivers/scsi/fd_mcs.c.
738
739 fdomain= [HW,SCSI]
740 See header of drivers/scsi/fdomain.c.
741
742 floppy= [HW]
31c00fc1 743 See Documentation/blockdev/floppy.txt.
1da177e4 744
f13ae30e
AC
745 force_pal_cache_flush
746 [IA-64] Avoid check_sal_cache_flush which may hang on
747 buggy SAL_CACHE_FLUSH implementations. Using this
748 parameter will force ia64_sal_cache_flush to call
749 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
750
1da177e4
LT
751 gamecon.map[2|3]=
752 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
753 support via parallel port (up to 5 devices per port)
754 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
755 See also Documentation/input/joystick-parport.txt
756
757 gamma= [HW,DRM]
758
aaf23042
YL
759 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
760 Format: off | on
761 default: on
762
1da177e4
LT
763 gdth= [HW,SCSI]
764 See header of drivers/scsi/gdth.c.
765
766 gpt [EFI] Forces disk with valid GPT signature but
767 invalid Protective MBR to be treated as GPT.
768
1da177e4
LT
769 gvp11= [HW,SCSI]
770
771 hashdist= [KNL,NUMA] Large hashes allocated during boot
772 are distributed across NUMA nodes. Defaults on
773 for IA-64, off otherwise.
a9913044 774 Format: 0 | 1 (for off | on)
1da177e4
LT
775
776 hcl= [IA-64] SGI's Hardware Graph compatibility layer
777
778 hd= [EIDE] (E)IDE hard drive subsystem geometry
779 Format: <cyl>,<head>,<sect>
780
1da177e4
LT
781 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
782 size of <nn>. This works even on boxes that have no
783 highmem otherwise. This also works to reduce highmem
784 size on bigger boxes.
785
54cdfdb4
TG
786 highres= [KNL] Enable/disable high resolution timer mode.
787 Valid parameters: "on", "off"
788 Default: "on"
789
1da177e4
LT
790 hisax= [HW,ISDN]
791 See Documentation/isdn/README.HiSax.
792
b4718e62
AK
793 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
794 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
795 On x86-64 and powerpc, this option can be specified
796 multiple times interleaved with hugepages= to reserve
797 huge pages of different sizes. Valid pages sizes on
798 x86-64 are 2M (when the CPU supports "pse") and 1G
799 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
800 Note that 1GB pages can only be allocated at boot time
801 using hugepages= and not freed afterwards.
e11bfbfc
NP
802 default_hugepagesz=
803 [same as hugepagesz=] The size of the default
804 HugeTLB page size. This is the size represented by
805 the legacy /proc/ hugepages APIs, used for SHM, and
806 default size when mounting hugetlbfs filesystems.
807 Defaults to the default architecture's huge page size
808 if not specified.
1da177e4 809
6902aa84
PM
810 hlt [BUGS=ARM,SH]
811
36d95739 812 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 813 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
814 i8042.dumbkbd [HW] Pretend that controller can only read data from
815 keyboard and cannot control its state
1da177e4
LT
816 (Don't attempt to blink the leds)
817 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 818 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
819 i8042.noloop [HW] Disable the AUX Loopback command while probing
820 for the AUX port
1da177e4
LT
821 i8042.nomux [HW] Don't check presence of an active multiplexing
822 controller
823 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
824 controllers
825 i8042.panicblink=
826 [HW] Frequency with which keyboard LEDs should blink
827 when kernel panics (default is 0.5 sec)
828 i8042.reset [HW] Reset the controller during init and cleanup
829 i8042.unlock [HW] Unlock (ignore) the keylock
830
831 i810= [HW,DRM]
832
e70c9d5e
DT
833 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
834 indicates that the driver is running on unsupported
835 hardware.
1da177e4
LT
836 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
837 does not match list of supported models.
838 i8k.power_status
839 [HW] Report power status in /proc/i8k
840 (disabled by default)
841 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
842 capability is set.
843
844 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
845 See Documentation/mca.txt.
846
847 icn= [HW,ISDN]
848 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
849
850 ide= [HW] (E)IDE subsystem
a594eeb1 851 Format: ide=nodma or ide=doubler
1c10e938 852 See Documentation/ide/ide.txt.
1da177e4 853
1da177e4 854 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
1c10e938 855 See Documentation/ide/ide.txt.
1da177e4 856
f039b754 857 idle= [X86]
da5e09a1 858 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
f039b754
AK
859 Poll forces a polling idle loop that can slightly improves the performance
860 of waking up a idle CPU, but will use a lot of power and make the system
861 run hot. Not recommended.
862 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
863 to not use it because it doesn't save as much power as a normal idle
864 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
865 as idle=poll.
c1e3b377
ZY
866 idle=halt. Halt is forced to be used for CPU idle.
867 In such case C2/C3 won't be used again.
da5e09a1 868 idle=nomwait. Disable mwait for CPU C-states
a9913044 869
594765a7
DC
870 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
871 Claim all unknown PCI IDE storage controllers.
872
79290822
IM
873 ignore_loglevel [KNL]
874 Ignore loglevel setting - this will print /all/
875 kernel messages to the console. Useful for debugging.
876
1da177e4
LT
877 ihash_entries= [KNL]
878 Set number of hash buckets for inode cache.
879
880 in2000= [HW,SCSI]
881 See header of drivers/scsi/in2000.c.
882
883 init= [KNL]
884 Format: <full_path>
885 Run specified binary instead of /sbin/init as init
886 process.
887
888 initcall_debug [KNL] Trace initcalls as they are executed. Useful
889 for working out where the kernel is dying during
890 startup.
891
892 initrd= [BOOT] Specify the location of the initial ramdisk
893
894 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
895 Format: <irq>
896
897 inttest= [IA64]
898
b552da87
PM
899 iommu= [x86]
900 off
901 force
902 noforce
903 biomerge
904 panic
905 nopanic
906 merge
907 nomerge
908 forcesac
909 soft
910
911
ba395927
KA
912 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
913 off
914 Disable intel iommu driver.
915 igfx_off [Default Off]
916 By default, gfx is mapped as normal device. If a gfx
917 device has a dedicated DMAR unit, the DMAR unit is
918 bypassed by not enabling DMAR with this option. In
919 this case, gfx device will use physical address for
920 DMA.
7d3b03ce
KA
921 forcedac [x86_64]
922 With this option iommu will not optimize to look
923 for io virtual address below 32 bit forcing dual
924 address cycle on pci bus for cards supporting greater
925 than 32 bit addressing. The default is to look
926 for translation below 32 bit and if not available
927 then look in the higher range.
5e0d2a6f 928 strict [Default Off]
929 With this option on every unmap_single operation will
930 result in a hardware IOTLB flush operation as opposed
931 to batching them for performance.
ba395927 932
b02aae9c 933 io_delay= [X86-32,X86-64] I/O delay method
6e7c4025
IM
934 0x80
935 Standard port 0x80 based delay
936 0xed
937 Alternate port 0xed based delay (needed on some systems)
b02aae9c 938 udelay
6e7c4025
IM
939 Simple two microseconds delay
940 none
941 No delay
b02aae9c 942
1da177e4
LT
943 io7= [HW] IO7 for Marvel based alpha systems
944 See comment before marvel_specify_io7 in
945 arch/alpha/kernel/core_marvel.c.
946
947 ip= [IP_PNP]
6ded55da 948 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
949
950 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
951 See comment before ip2_setup() in
952 drivers/char/ip2/ip2base.c.
1da177e4
LT
953
954 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
955 See header of drivers/scsi/ips.c.
956
72c4a13a
SH
957 ports= [IP_VS_FTP] IPVS ftp helper module
958 Default is 21.
959 Up to 8 (IP_VS_APP_MAX_PORTS) ports
960 may be specified.
961 Format: <port>,<port>....
962
200803df
AC
963 irqfixup [HW]
964 When an interrupt is not handled search all handlers
965 for it. Intended to get systems with badly broken
966 firmware running.
967
968 irqpoll [HW]
969 When an interrupt is not handled search all handlers
970 for it. Also check all handlers each timer
971 interrupt. Intended to get systems with badly broken
972 firmware running.
973
1da177e4 974 isapnp= [ISAPNP]
a9913044 975 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
976
977 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
978 Format:
979 <cpu number>,...,<cpu number>
980 or
b225d44e
LZ
981 <cpu number>-<cpu number>
982 (must be a positive range in ascending order)
22f2e280
DF
983 or a mixture
984 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 985
1da177e4
LT
986 This option can be used to specify one or more CPUs
987 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
988 algorithms. You can move a process onto or off an
989 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
990 <cpu number> begins at 0 and the maximum value is
991 "number of CPUs in system - 1".
992
993 This option is the preferred way to isolate CPUs. The
a9913044
RD
994 alternative -- manually setting the CPU mask of all
995 tasks in the system -- can cause problems and
996 suboptimal load balancer performance.
1da177e4 997
a9913044 998 iucv= [HW,NET]
1da177e4
LT
999
1000 js= [HW,JOY] Analog joystick
1001 See Documentation/input/joystick.txt.
1002
cd4f0ef7 1003 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
ed7ed365
MG
1004 specifies the amount of memory usable by the kernel
1005 for non-movable allocations. The requested amount is
1006 spread evenly throughout all nodes in the system. The
1007 remaining memory in each node is used for Movable
1008 pages. In the event, a node is too small to have both
1009 kernelcore and Movable pages, kernelcore pages will
1010 take priority and other nodes will have a larger number
1011 of kernelcore pages. The Movable zone is used for the
1012 allocation of pages that may be reclaimed or moved
1013 by the page migration subsystem. This means that
1014 HugeTLB pages may not be allocated from this zone.
1015 Note that allocations like PTEs-from-HighMem still
1016 use the HighMem zone if it exists, and the Normal
1017 zone if it does not.
1018
cd4f0ef7 1019 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
7e63efef
MG
1020 is similar to kernelcore except it specifies the
1021 amount of memory used for migratable allocations.
1022 If both kernelcore and movablecore is specified,
1023 then kernelcore will be at *least* the specified
1024 value but may be more. If movablecore on its own
1025 is specified, the administrator must be careful
1026 that the amount of memory usable for all allocations
1027 is not too small.
1028
1da177e4
LT
1029 keepinitrd [HW,ARM]
1030
cd4f0ef7 1031 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1da177e4
LT
1032 in oops dumps.
1033
6cdf6e06
JW
1034 kgdboc= [HW] kgdb over consoles.
1035 Requires a tty driver that supports console polling.
1036 (only serial suported for now)
1037 Format: <serial_device>[,baud]
1038
9bed90c6
FF
1039 kmac= [MIPS] korina ethernet MAC address.
1040 Configure the RouterBoard 532 series on-chip
1041 Ethernet adapter MAC address.
1042
1da177e4
LT
1043 l2cr= [PPC]
1044
a78bfbfc
RB
1045 l3cr= [PPC]
1046
cd4f0ef7 1047 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1048 disabled it.
1da177e4 1049
cd4f0ef7 1050 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
e585bef8
TG
1051 C2 power state.
1052
fcb71f6f
FC
1053 libata.dma= [LIBATA] DMA control
1054 libata.dma=0 Disable all PATA and SATA DMA
1055 libata.dma=1 PATA and SATA Disk DMA only
1056 libata.dma=2 ATAPI (CDROM) DMA only
1057 libata.dma=4 Compact Flash DMA only
1058 Combinations also work, so libata.dma=3 enables DMA
1059 for disks and CDROMs, but not CFs.
1060
78e70c23
DJ
1061 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1062 when set.
1063 Format: <int>
1064
33267325
TH
1065 libata.force= [LIBATA] Force configurations. The format is comma
1066 separated list of "[ID:]VAL" where ID is
1067 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1068 matching port, link or device. Basically, it matches
1069 the ATA ID string printed on console by libata. If
1070 the whole ID part is omitted, the last PORT and DEVICE
1071 values are used. If ID hasn't been specified yet, the
1072 configuration applies to all ports, links and devices.
1073
1074 If only DEVICE is omitted, the parameter applies to
1075 the port and all links and devices behind it. DEVICE
1076 number of 0 either selects the first device or the
1077 first fan-out link behind PMP device. It does not
1078 select the host link. DEVICE number of 15 selects the
1079 host link and device attached to it.
1080
1081 The VAL specifies the configuration to force. As long
1082 as there's no ambiguity shortcut notation is allowed.
1083 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1084 The following configurations can be forced.
1085
1086 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1087 Any ID with matching PORT is used.
1088
1089 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1090
1091 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1092 udma[/][16,25,33,44,66,100,133] notation is also
1093 allowed.
1094
1095 * [no]ncq: Turn on or off NCQ.
1096
05944bdf
TH
1097 * nohrst, nosrst, norst: suppress hard, soft
1098 and both resets.
1099
33267325
TH
1100 If there are multiple matching configurations changing
1101 the same attribute, the last one is used.
1102
1da177e4 1103 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1104 See Documentation/blockdev/ramdisk.txt.
1da177e4 1105
a6b25b67
RD
1106 lockd.nlm_grace_period=P [NFS] Assign grace period.
1107 Format: <integer>
1da177e4 1108
a6b25b67
RD
1109 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1110 Format: <integer>
1111
1112 lockd.nlm_timeout=T [NFS] Assign timeout value.
1113 Format: <integer>
1114
1115 lockd.nlm_udpport=M [NFS] Assign UDP port.
1116 Format: <integer>
1da177e4
LT
1117
1118 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1119 Format: <irq>
1120
1121 loglevel= All Kernel Messages with a loglevel smaller than the
1122 console loglevel will be printed to the console. It can
1123 also be changed with klogd or other programs. The
1124 loglevels are defined as follows:
1125
1126 0 (KERN_EMERG) system is unusable
1127 1 (KERN_ALERT) action must be taken immediately
1128 2 (KERN_CRIT) critical conditions
1129 3 (KERN_ERR) error conditions
1130 4 (KERN_WARNING) warning conditions
1131 5 (KERN_NOTICE) normal but significant condition
1132 6 (KERN_INFO) informational
1133 7 (KERN_DEBUG) debug-level messages
1134
1135 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1136 Format: { n | nk | nM }
1137 n must be a power of two. The default size
1138 is set in the kernel config file.
1da177e4 1139
accaa24c
RD
1140 logo.nologo [FB] Disables display of the built-in Linux logo.
1141 This may be used to provide more screen space for
1142 kernel log messages and is useful when debugging
1143 kernel boot problems.
1144
1da177e4
LT
1145 lp=0 [LP] Specify parallel ports to use, e.g,
1146 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1147 lp=reset first parallel port). 'lp=0' disables the
1148 lp=auto printer driver. 'lp=reset' (which can be
1149 specified in addition to the ports) causes
1150 attached printers to be reset. Using
1151 lp=port1,port2,... specifies the parallel ports
1152 to associate lp devices with, starting with
1153 lp0. A port specification may be 'none' to skip
1154 that lp device, or a parport name such as
1155 'parport0'. Specifying 'lp=auto' instead of a
1156 port specification list means that device IDs
1157 from each port should be examined, to see if
1158 an IEEE 1284-compliant printer is attached; if
1159 so, the driver will manage that printer.
1160 See also header of drivers/char/lp.c.
1161
1162 lpj=n [KNL]
1163 Sets loops_per_jiffy to given constant, thus avoiding
1164 time-consuming boot-time autodetection (up to 250 ms per
1165 CPU). 0 enables autodetection (default). To determine
1166 the correct value for your kernel, boot with normal
1167 autodetection and see what value is printed. Note that
1168 on SMP systems the preset will be applied to all CPUs,
1169 which is likely to cause problems if your CPUs need
1170 significantly divergent settings. An incorrect value
1171 will cause delays in the kernel to be wrong, leading to
1172 unpredictable I/O errors and other breakage. Although
1173 unlikely, in the extreme case this might damage your
1174 hardware.
1175
1176 ltpc= [NET]
1177 Format: <io>,<irq>,<dma>
1178
a9913044
RD
1179 mac5380= [HW,SCSI] Format:
1180 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1181
a9913044
RD
1182 machvec= [IA64] Force the use of a particular machine-vector
1183 (machvec) in a generic kernel.
1184 Example: machvec=hpzx1_swiotlb
1da177e4 1185
a9913044 1186 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
1187 be mounted
1188 Format: <1-256>
1189
1190 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1191 should make use of. maxcpus=n : n >= 0 limits the
1192 kernel to using 'n' processors. n=0 is a special case,
1193 it is equivalent to "nosmp", which also disables
1194 the IO APIC.
1da177e4 1195
1c207f95
RD
1196 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1197 or equal to this physical address is ignored.
2b2c3750 1198
a9913044 1199 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1200 Should be between 1 and 2^32-1.
1201
1202 max_report_luns=
a9913044 1203 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1204 Should be between 1 and 16384.
1205
1da177e4
LT
1206 mcatest= [IA-64]
1207
cd4f0ef7 1208 mce [X86-32] Machine Check Exception
1da177e4 1209
71cced6e 1210 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1211
1da177e4
LT
1212 md= [HW] RAID subsystems devices and level
1213 See Documentation/md.txt.
a9913044 1214
1da177e4
LT
1215 mdacon= [MDA]
1216 Format: <first>,<last>
1217 Specifies range of consoles to be captured by the MDA.
a9913044 1218
1da177e4
LT
1219 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1220 Amount of memory to be used when the kernel is not able
1221 to see the whole system memory or for test.
cd4f0ef7 1222 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1223 address space collisions. Without memmap= PCI devices
1224 could be placed at addresses belonging to unused RAM.
1225
cd4f0ef7 1226 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1227 memory.
1228
6902aa84
PM
1229 memchunk=nn[KMG]
1230 [KNL,SH] Allow user to override the default size for
1231 per-device physically contiguous DMA buffers.
1232
cd4f0ef7 1233 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1da177e4
LT
1234 E820 memory map, as specified by the user.
1235 Such memmap=exactmap lines can be constructed based on
1236 BIOS output or other requirements. See the memmap=nn@ss
1237 option description.
1238
1239 memmap=nn[KMG]@ss[KMG]
1240 [KNL] Force usage of a specific region of memory
1241 Region of memory to be used, from ss to ss+nn.
1242
1243 memmap=nn[KMG]#ss[KMG]
1244 [KNL,ACPI] Mark specific memory as ACPI data.
1245 Region of memory to be used, from ss to ss+nn.
1246
1247 memmap=nn[KMG]$ss[KMG]
1248 [KNL,ACPI] Mark specific memory as reserved.
1249 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1250 Example: Exclude memory from 0x18690000-0x1869ffff
1251 memmap=64K$0x18690000
1252 or
1253 memmap=0x10000$0x18690000
1da177e4 1254
9f077871
JF
1255 memory_corruption_check=0/1 [X86]
1256 Some BIOSes seem to corrupt the first 64k of
1257 memory when doing things like suspend/resume.
1258 Setting this option will scan the memory
1259 looking for corruption. Enabling this will
1260 both detect corruption and prevent the kernel
1261 from using the memory being corrupted.
1262 However, its intended as a diagnostic tool; if
1263 repeatable BIOS-originated corruption always
1264 affects the same memory, you can use memmap=
1265 to prevent the kernel from using that memory.
1266
1267 memory_corruption_check_size=size [X86]
1268 By default it checks for corruption in the low
1269 64k, making this memory unavailable for normal
1270 use. Use this parameter to scan for
1271 corruption in more or less memory.
1272
1273 memory_corruption_check_period=seconds [X86]
1274 By default it checks for corruption every 60
1275 seconds. Use this parameter to check at some
1276 other rate. 0 disables periodic checking.
1277
caadbdce 1278 memtest= [KNL,X86] Enable memtest
c64df707
YL
1279 Format: <integer>
1280 range: 0,4 : pattern number
1281 default : 0 <disable>
1282
1da177e4
LT
1283 meye.*= [HW] Set MotionEye Camera parameters
1284 See Documentation/video4linux/meye.txt.
1285
8f36881b
AS
1286 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1287 Multi-Function General Purpose Timers on AMD Geode
1288 platforms.
1289
e6c4dc6c
WT
1290 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1291 the BIOS has incorrectly applied a workaround. TinyBIOS
1292 version 0.98 is known to be affected, 0.99 fixes the
1293 problem by letting the user disable the workaround.
1294
1da177e4
LT
1295 mga= [HW,DRM]
1296
1c207f95
RD
1297 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1298 physical address is ignored.
1299
6b74ab97
MG
1300 mminit_loglevel=
1301 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1302 parameter allows control of the logging verbosity for
1303 the additional memory initialisation checks. A value
1304 of 0 disables mminit logging and a level of 4 will
1305 log everything. Information is printed at KERN_DEBUG
1306 so loglevel=8 may also need to be specified.
1307
1da177e4
LT
1308 mousedev.tap_time=
1309 [MOUSE] Maximum time between finger touching and
1310 leaving touchpad surface for touch to be considered
1311 a tap and be reported as a left button click (for
1312 touchpads working in absolute mode only).
1313 Format: <msecs>
1314 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1315 reporting absolute coordinates, such as tablets
1316 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1317 reporting absolute coordinates, such as tablets
1318
1319 mpu401= [HW,OSS]
1320 Format: <io>,<irq>
1321
1322 MTD_Partition= [MTD]
1323 Format: <name>,<region-number>,<size>,<offset>
1324
a9913044
RD
1325 MTD_Region= [MTD] Format:
1326 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1327
1328 mtdparts= [MTD]
c8facbb6 1329 See drivers/mtd/cmdlinepart.c.
1da177e4 1330
9db829f4
BD
1331 mtdset= [ARM]
1332 ARM/S3C2412 JIVE boot control
1333
1334 See arch/arm/mach-s3c2412/mach-jive.c
1335
1da177e4 1336 mtouchusb.raw_coordinates=
a9913044
RD
1337 [HW] Make the MicroTouch USB driver use raw coordinates
1338 ('y', default) or cooked coordinates ('n')
1da177e4
LT
1339
1340 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1341
1342 NCR_D700= [HW,SCSI]
1343 See header of drivers/scsi/NCR_D700.c.
1344
1345 ncr5380= [HW,SCSI]
1346
1347 ncr53c400= [HW,SCSI]
1348
1349 ncr53c400a= [HW,SCSI]
1350
1351 ncr53c406a= [HW,SCSI]
1352
1353 ncr53c8xx= [HW,SCSI]
1354
1355 netdev= [NET] Network devices parameters
1356 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1357 Note that mem_start is often overloaded to mean
1358 something different and driver-specific.
a9913044
RD
1359 This usage is only documented in each driver source
1360 file if at all.
1361
58401572
KPO
1362 nf_conntrack.acct=
1363 [NETFILTER] Enable connection tracking flow accounting
1364 0 to disable accounting
1365 1 to enable accounting
1366 Default value depends on CONFIG_NF_CT_ACCT that is
1367 going to be removed in 2.6.29.
1368
1da177e4 1369 nfsaddrs= [NFS]
6ded55da 1370 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
1371
1372 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
6ded55da 1373 See Documentation/filesystems/nfsroot.txt.
1da177e4 1374
a72b4422
TM
1375 nfs.callback_tcpport=
1376 [NFS] set the TCP port on which the NFSv4 callback
1377 channel should listen.
1378
58df095b
TM
1379 nfs.idmap_cache_timeout=
1380 [NFS] set the maximum lifetime for idmapper cache
1381 entries.
1382
f43bf0be
TM
1383 nfs.enable_ino64=
1384 [NFS] enable 64-bit inode numbers.
1385 If zero, the NFS client will fake up a 32-bit inode
1386 number for the readdir() and stat() syscalls instead
1387 of returning the full 64-bit number.
1388 The default is to return 64-bit inode numbers.
1389
e7ba176b
HS
1390 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1391 when a NMI is triggered.
1392 Format: [state][,regs][,debounce][,die]
1393
cd4f0ef7 1394 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1da177e4 1395
cd4f0ef7 1396 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1397 emulation library even if a 387 maths coprocessor
1398 is present.
1399
c1aee215
CL
1400 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1401 caches in the slab allocator. Saves per-node memory,
1402 but will impact performance.
3395ee05 1403
a9913044
RD
1404 noalign [KNL,ARM]
1405
1da177e4
LT
1406 noapic [SMP,APIC] Tells the kernel to not make use of any
1407 IOAPICs that may be present in the system.
1408
1da177e4
LT
1409 nobats [PPC] Do not use BATs for mapping kernel lowmem
1410 on "Classic" PPC cores.
1411
1412 nocache [ARM]
a9913044 1413
163ecdff
SN
1414 nodelayacct [KNL] Disable per-task delay accounting
1415
1da177e4
LT
1416 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1417
6902aa84
PM
1418 nodsp [SH] Disable hardware DSP at boot time.
1419
8b2cb7a8
HY
1420 noefi [X86-32,X86-64] Disable EFI runtime services support.
1421
1da177e4
LT
1422 noexec [IA-64]
1423
cd4f0ef7 1424 noexec [X86-32,X86-64]
f5a1b191 1425 On X86-32 available only on PAE configured kernels.
1da177e4 1426 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1427 noexec=off: disable non-executable mappings
1428
1429 noexec32 [X86-64]
1430 This affects only 32-bit executables.
1431 noexec32=on: enable non-executable mappings (default)
1432 read doesn't imply executable mappings
1433 noexec32=off: disable non-executable mappings
1434 read implies executable mappings
1da177e4 1435
6902aa84
PM
1436 nofpu [SH] Disable hardware FPU at boot time.
1437
cd4f0ef7 1438 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1439 register save and restore. The kernel will only save
1440 legacy floating-point registers on task switch.
1da177e4 1441
191679fd
AK
1442 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1443
6902aa84 1444 nohlt [BUGS=ARM,SH]
a9913044 1445
cd4f0ef7 1446 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1447 instruction doesn't work correctly and not to
1448 use it.
1449
1450 nohalt [IA-64] Tells the kernel not to use the power saving
1451 function PAL_HALT_LIGHT when idle. This increases
1452 power-consumption. On the positive side, it reduces
1453 interrupt wake-up latency, which may improve performance
1454 in certain environments such as networked servers or
1455 real-time systems.
1456
79bf2bb3
TG
1457 nohz= [KNL] Boottime enable/disable dynamic ticks
1458 Valid arguments: on, off
1459 Default: on
1460
cd4f0ef7 1461 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1462 disable unhandled interrupt sources.
1463
cd4f0ef7 1464 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
8542b200
ZA
1465 broken timer IRQ sources.
1466
1da177e4
LT
1467 noisapnp [ISAPNP] Disables ISA PnP code.
1468
1469 noinitrd [RAM] Tells the kernel not to load any configured
1470 initial RAM disk.
1471
1472 nointroute [IA-64]
1473
0aa366f3
TL
1474 nojitter [IA64] Disables jitter checking for ITC timers.
1475
cd4f0ef7 1476 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1477
cd4f0ef7 1478 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1479
6e1cb38a
SS
1480 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1481
af9d1388
SS
1482 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1483 default x2apic cluster mode on platforms
1484 supporting x2apic.
1485
1da177e4
LT
1486 noltlbs [PPC] Do not use large page/tlb entries for kernel
1487 lowmem mapping on PPC40x.
1488
312f1f01
H
1489 nomca [IA-64] Disable machine check abort handling
1490
cd4f0ef7 1491 nomce [X86-32] Machine Check Exception
abe37e5a 1492
83d7384f
AS
1493 nomfgpt [X86-32] Disable Multi-Function General Purpose
1494 Timer usage (for AMD Geode machines).
1495
cd4f0ef7 1496 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1497
cd4f0ef7 1498 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1499 with UP alternatives
1500
1da177e4
LT
1501 noresidual [PPC] Don't use residual data on PReP machines.
1502
a9913044
RD
1503 noresume [SWSUSP] Disables resume and restores original swap
1504 space.
1505
1da177e4
LT
1506 no-scroll [VGA] Disables scrollback.
1507 This is required for the Braillex ib80-piezo Braille
1508 reader made by F.H. Papenmeier (Germany).
1509
1510 nosbagart [IA-64]
1511
cd4f0ef7 1512 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1513
61ec7567
LB
1514 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1515 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1516
97842216
DJ
1517 nosoftlockup [KNL] Disable the soft-lockup detector.
1518
1da177e4
LT
1519 nosync [HW,M68K] Disables sync negotiation for all devices.
1520
cd4f0ef7 1521 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1522
1523 nousb [USB] Disable the USB subsystem
1524
1525 nowb [ARM]
a9913044 1526
a6c75b86
FY
1527 nptcg= [IA64] Override max number of concurrent global TLB
1528 purges which is reported from either PAL_VM_SUMMARY or
1529 SAL PALO.
1530
f0c0b2b8
KH
1531 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1532 one of ['zone', 'node', 'default'] can be specified
1533 This can be set from sysctl after boot.
1534 See Documentation/sysctl/vm.txt for details.
1535
a61c2d78
DJ
1536 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1537
3ef0e1f8
AS
1538 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1539 Rather than timing out after 20 ms if an EC
1540 command is not properly ACKed, override the length
1541 of the timeout. We have interrupts disabled while
1542 waiting for the ACK, so if this is set too high
1543 interrupts *may* be lost!
1544
1da177e4
LT
1545 opl3= [HW,OSS]
1546 Format: <io>
1547
1da177e4
LT
1548 oprofile.timer= [HW]
1549 Use timer interrupt instead of performance counters
1550
1da177e4
LT
1551 osst= [HW,SCSI] SCSI Tape Driver
1552 Format: <buffer_size>,<write_threshold>
1553 See also Documentation/scsi/st.txt.
1554
1555 panic= [KNL] Kernel behaviour on panic
1556 Format: <timeout>
1557
1558 parkbd.port= [HW] Parallel port number the keyboard adapter is
1559 connected to, default is 0.
1560 Format: <parport#>
1561 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1562 0 for XT, 1 for AT (default is AT).
a9913044
RD
1563 Format: <mode>
1564
1565 parport= [HW,PPT] Specify parallel ports. 0 disables.
1566 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1567 Use 'auto' to force the driver to use any
1568 IRQ/DMA settings detected (the default is to
1569 ignore detected IRQ/DMA settings because of
1570 possible conflicts). You can specify the base
1571 address, IRQ, and DMA settings; IRQ and DMA
1572 should be numbers, or 'auto' (for using detected
1573 settings on that particular port), or 'nofifo'
1574 (to avoid using a FIFO even if it is detected).
1575 Parallel ports are assigned in the order they
1576 are specified on the command line, starting
1577 with parport0.
1578
1579 parport_init_mode= [HW,PPT]
1580 Configure VIA parallel port to operate in
1581 a specific mode. This is necessary on Pegasos
1582 computer where firmware has no options for setting
1583 up parallel port mode and sets it to spp.
1584 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1585 Format: [spp|ps2|epp|ecp|ecpepp]
1586
a9913044
RD
1587 pas2= [HW,OSS] Format:
1588 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1589
1da177e4
LT
1590 pas16= [HW,SCSI]
1591 See header of drivers/scsi/pas16.c.
1592
dd287796
AM
1593 pause_on_oops=
1594 Halt all CPUs after the first oops has been printed for
1595 the specified number of seconds. This is to be used if
1596 your oopses keep scrolling off the screen.
1597
1da177e4
LT
1598 pcbit= [HW,ISDN]
1599
1600 pcd. [PARIDE]
1601 See header of drivers/block/paride/pcd.c.
31c00fc1 1602 See also Documentation/blockdev/paride.txt.
1da177e4 1603
a9913044 1604 pci=option[,option...] [PCI] various PCI subsystem options:
c0115606 1605 off [X86] don't probe for the PCI bus
cd4f0ef7 1606 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1607 the hardware directly. Use this if your machine
1608 has a non-standard PCI host bridge.
cd4f0ef7 1609 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1610 hardware access methods are allowed. Use this
1611 if you experience crashes upon bootup and you
1612 suspect they are caused by the BIOS.
c0115606 1613 conf1 [X86] Force use of PCI Configuration
a9913044 1614 Mechanism 1.
c0115606 1615 conf2 [X86] Force use of PCI Configuration
a9913044 1616 Mechanism 2.
7f785763
RD
1617 noaer [PCIE] If the PCIEAER kernel config parameter is
1618 enabled, this kernel boot option can be used to
1619 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1620 nodomains [PCI] Disable support for multiple PCI
1621 root domains (aka PCI segments, in ACPI-speak).
cd4f0ef7 1622 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
61be6d66 1623 Configuration
309e57df
MW
1624 nomsi [MSI] If the PCI_MSI kernel config parameter is
1625 enabled, this kernel boot option can be used to
1626 disable the use of MSI interrupts system-wide.
cd4f0ef7 1627 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1628 routing table. These calls are known to be buggy
1629 on several machines and they hang the machine
1630 when used, but on other computers it's the only
1631 way to get the interrupt routing table. Try
1632 this option if the kernel is unable to allocate
1633 IRQs or discover secondary PCI buses on your
1634 motherboard.
c0115606 1635 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1636 Use with caution as certain devices share
1637 address decoders between ROMs and other
1638 resources.
c0115606 1639 norom [X86] Do not assign address space to
bb71ad88
GH
1640 expansion ROMs that do not already have
1641 BIOS assigned address ranges.
c0115606 1642 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1643 assigned automatically to PCI devices. You can
1644 make the kernel exclude IRQs of your ISA cards
1645 this way.
c0115606 1646 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1647 of the PIRQ table (normally generated
1648 by the BIOS) if it is outside the
1649 F0000h-100000h range.
c0115606 1650 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1651 useful if the kernel is unable to find your
1652 secondary buses and you want to tell it
1653 explicitly which ones they are.
c0115606 1654 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1655 numbers ourselves, overriding
1656 whatever the firmware may have done.
c0115606 1657 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1658 in the BIOS $PIR table. This is needed on
1659 some systems with broken BIOSes, notably
1660 some HP Pavilion N5400 and Omnibook XE3
1661 notebooks. This will have no effect if ACPI
1662 IRQ routing is enabled.
c0115606 1663 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1664 or for PCI scanning.
c0115606 1665 use_crs [X86] Use _CRS for PCI resource
62f420f8 1666 allocation.
a9913044
RD
1667 routeirq Do IRQ routing for all PCI devices.
1668 This is normally done in pci_enable_device(),
1669 so this option is a temporary workaround
1670 for broken drivers that don't call it.
13a6ddb0
YL
1671 skip_isa_align [X86] do not align io start addr, so can
1672 handle more pci cards
a9913044
RD
1673 firmware [ARM] Do not re-enumerate the bus but instead
1674 just use the configuration from the
1675 bootloader. This is currently used on
1676 IXP2000 systems where the bus has to be
1677 configured a certain way for adjunct CPUs.
0637a70a
AK
1678 noearly [X86] Don't do any early type 1 scanning.
1679 This might help on some broken boards which
1680 machine check when some devices' config space
1681 is read. But various workarounds are disabled
1682 and some IOMMU drivers will not work.
6b4b78fe
MD
1683 bfsort Sort PCI devices into breadth-first order.
1684 This sorting is done to get a device
1685 order compatible with older (<= 2.4) kernels.
1686 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1687 cbiosize=nn[KMG] The fixed amount of bus space which is
1688 reserved for the CardBus bridge's IO window.
1689 The default value is 256 bytes.
1690 cbmemsize=nn[KMG] The fixed amount of bus space which is
1691 reserved for the CardBus bridge's memory
1692 window. The default value is 64 megabytes.
6b4b78fe 1693
e5665a45
CE
1694 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1695 Management.
1696 off Disable ASPM.
1697 force Enable ASPM even on devices that claim not to support it.
1698 WARNING: Forcing ASPM on may cause system lockups.
1699
1da177e4
LT
1700 pcmv= [HW,PCMCIA] BadgePAD 4
1701
1702 pd. [PARIDE]
31c00fc1 1703 See Documentation/blockdev/paride.txt.
1da177e4
LT
1704
1705 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1706 boot time.
1707 Format: { 0 | 1 }
1708 See arch/parisc/kernel/pdc_chassis.c
1709
1710 pf. [PARIDE]
31c00fc1 1711 See Documentation/blockdev/paride.txt.
1da177e4
LT
1712
1713 pg. [PARIDE]
31c00fc1 1714 See Documentation/blockdev/paride.txt.
1da177e4
LT
1715
1716 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 1717 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
1718
1719 plip= [PPT,NET] Parallel port network link
1720 Format: { parport<nr> | timid | 0 }
1721 See also Documentation/parport.txt.
1722
de32a243
TG
1723 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1724 Override pmtimer IOPort with a hex value.
1725 e.g. pmtmr=0x508
1726
97ef062b
BH
1727 pnp.debug [PNP]
1728 Enable PNP debug messages. This depends on the
1729 CONFIG_PNP_DEBUG_MESSAGES option.
1730
1da177e4
LT
1731 pnpacpi= [ACPI]
1732 { off }
1733
1734 pnpbios= [ISAPNP]
1735 { on | off | curr | res | no-curr | no-res }
1736
1737 pnp_reserve_irq=
1738 [ISAPNP] Exclude IRQs for the autoconfiguration
1739
1740 pnp_reserve_dma=
1741 [ISAPNP] Exclude DMAs for the autoconfiguration
1742
1743 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1744 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1745
1746 pnp_reserve_mem=
a9913044
RD
1747 [ISAPNP] Exclude memory regions for the
1748 autoconfiguration.
1da177e4
LT
1749 Ranges are in pairs (memory base and size).
1750
346e15be
JB
1751 dynamic_printk
1752 Enables pr_debug()/dev_dbg() calls if
1753 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1754 be switched on/off via <debugfs>/dynamic_printk/modules
1755
45807a1d
IM
1756 print-fatal-signals=
1757 [KNL] debug: print fatal signals
1758 print-fatal-signals=1: print segfault info to
1759 the kernel console.
1760 default: off.
1761
e84845c4
RD
1762 printk.time= Show timing data prefixed to each printk message line
1763 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1764
1da177e4 1765 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1766 Format: [schedule,]<number>
1767 Param: "schedule" - profile schedule points.
1768 Param: <number> - step/bucket size as a power of 2 for
1769 statistical time based profiling.
b3da2a73
MG
1770 Param: "sleep" - profile D-state sleeping (millisecs).
1771 Requires CONFIG_SCHEDSTATS
c0fe2e69 1772 Param: "kvm" - profile VM exits.
1da177e4 1773
a9913044 1774 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1775 Limit processor to maximum C-state
1776 max_cstate=9 overrides any DMI blacklist limit.
1777
41c0d868
LB
1778 processor.nocst [HW,ACPI]
1779 Ignore the _CST method to determine C-states,
1780 instead using the legacy FADT method
1781
1da177e4
LT
1782 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1783 before loading.
31c00fc1 1784 See Documentation/blockdev/ramdisk.txt.
1da177e4 1785
a9913044
RD
1786 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1787 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1788 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1789 per second.
a9913044
RD
1790 psmouse.resetafter= [HW,MOUSE]
1791 Try to reset the device after so many bad packets
1da177e4
LT
1792 (0 = never).
1793 psmouse.resolution=
1794 [HW,MOUSE] Set desired mouse resolution, in dpi.
1795 psmouse.smartscroll=
a9913044 1796 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1797 0 = disabled, 1 = enabled (default).
1798
1799 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1800 Format:
1801 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1802
1803 pt. [PARIDE]
31c00fc1 1804 See Documentation/blockdev/paride.txt.
1da177e4 1805
dc8c8587
KS
1806 pty.legacy_count=
1807 [KNL] Number of legacy pty's. Overwrites compiled-in
1808 default number.
1809
7d2c502f 1810 quiet [KNL] Disable most log messages
a9913044 1811
1da177e4
LT
1812 r128= [HW,DRM]
1813
1814 raid= [HW,RAID]
1815 See Documentation/md.txt.
1816
a9913044 1817 ramdisk_blocksize= [RAM]
31c00fc1 1818 See Documentation/blockdev/ramdisk.txt.
a9913044 1819
1da177e4 1820 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 1821 See Documentation/blockdev/ramdisk.txt.
1da177e4 1822
24aaef8d
RD
1823 rcupdate.blimit= [KNL,BOOT]
1824 Set maximum number of finished RCU callbacks to process
1825 in one batch.
21a1ea9e 1826
24aaef8d
RD
1827 rcupdate.qhimark= [KNL,BOOT]
1828 Set threshold of queued
21a1ea9e
DS
1829 RCU callbacks over which batch limiting is disabled.
1830
24aaef8d
RD
1831 rcupdate.qlowmark= [KNL,BOOT]
1832 Set threshold of queued RCU callbacks below which
1833 batch limiting is re-enabled.
21a1ea9e 1834
ffdfc409
OJ
1835 rdinit= [KNL]
1836 Format: <full_path>
1837 Run specified binary instead of /init from the ramdisk,
1838 used for early userspace startup. See initrd.
1839
cd4f0ef7 1840 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1841 Format: <reboot_mode>[,<reboot_mode2>[,...]]
e53dd083 1842 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 1843
46b6d94e
PJ
1844 relax_domain_level=
1845 [KNL, SMP] Set scheduler's default relax_domain_level.
1846 See Documentation/cpusets.txt.
1847
1da177e4
LT
1848 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1849
cd4f0ef7 1850 reservetop= [X86-32]
461a9aff
ZA
1851 Format: nn[KMG]
1852 Reserves a hole at the top of the kernel virtual
1853 address space.
1854
7e96287d
VG
1855 reset_devices [KNL] Force drivers to reset the underlying device
1856 during initialization.
1857
a9913044
RD
1858 resume= [SWSUSP]
1859 Specify the partition device for software suspend
1da177e4 1860
ecbd0da1
RW
1861 resume_offset= [SWSUSP]
1862 Specify the offset from the beginning of the partition
1863 given by "resume=" at which the swap header is located,
1864 in <PAGE_SIZE> units (needed only for swap files).
1865 See Documentation/power/swsusp-and-swap-files.txt
1866
0a7b35cb
MN
1867 retain_initrd [RAM] Keep initrd memory after extraction
1868
1da177e4
LT
1869 rhash_entries= [KNL,NET]
1870 Set number of hash buckets for route cache
1871
1872 riscom8= [HW,SERIAL]
1873 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1874
1875 ro [KNL] Mount root device read-only on boot
1876
1877 root= [KNL] Root filesystem
1878
1879 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1880 mount the root filesystem
1881
1882 rootflags= [KNL] Set root filesystem mount option string
1883
1884 rootfstype= [KNL] Set root filesystem type
1885
cc1ed754
PO
1886 rootwait [KNL] Wait (indefinitely) for root device to show up.
1887 Useful for devices that are detected asynchronously
1888 (e.g. USB and MMC devices).
1889
20510f2f
JM
1890 root_plug.vendor_id=
1891 [ROOTPLUG] Override the default vendor ID
1892
1893 root_plug.product_id=
1894 [ROOTPLUG] Override the default product ID
1895
1896 root_plug.debug=
1897 [ROOTPLUG] Enable debugging output
1898
1da177e4
LT
1899 rw [KNL] Mount root device read-write on boot
1900
1901 S [KNL] Run init in single mode
1902
1903 sa1100ir [NET]
1904 See drivers/net/irda/sa1100_ir.c.
1905
1da177e4 1906 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1907
1da177e4
LT
1908 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1909 Format: <io>[,<timeout>[,<isapnp>]]
1910
1911 scsi_debug_*= [SCSI]
1912 See drivers/scsi/scsi_debug.c.
1913
1914 scsi_default_dev_flags=
1915 [SCSI] SCSI default device flags
1916 Format: <integer>
1917
1918 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1919 Format: <vendor>:<model>:<flags>
1920 (flags are integer value)
1921
6af6632a
RD
1922 scsi_logging_level= [SCSI] a bit mask of logging levels
1923 See drivers/scsi/scsi_logging.h for bits. Also
1924 settable via sysctl at dev.scsi.logging_level
1925 (/proc/sys/dev/scsi/logging_level).
1926 There is also a nice 'scsi_logging_level' script in the
1927 S390-tools package, available for download at
1928 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 1929
3e082a91
MW
1930 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1931 discovered. async scans them in kernel threads,
1932 allowing boot to proceed. none ignores them, expecting
1933 user space to do the scan.
1934
1da177e4
LT
1935 selinux [SELINUX] Disable or enable SELinux at boot time.
1936 Format: { "0" | "1" }
1937 See security/selinux/Kconfig help text.
1938 0 -- disable.
1939 1 -- enable.
1940 Default value is set via kernel config option.
1941 If enabled at boot time, /selinux/disable can be used
1942 later to disable prior to initial policy load.
1943
4e5ab4cb
JM
1944 selinux_compat_net =
1945 [SELINUX] Set initial selinux_compat_net flag value.
e53dd083
MCC
1946 Format: { "0" | "1" }
1947 0 -- use new secmark-based packet controls
1948 1 -- use legacy packet controls
1949 Default value is 0 (preferred).
1950 Value can be changed at runtime via
1951 /selinux/compat_net.
4e5ab4cb 1952
cd4f0ef7 1953 serialnumber [BUGS=X86-32]
1da177e4 1954
1da177e4
LT
1955 shapers= [NET]
1956 Maximal number of shapers.
a9913044 1957
b05f78f5
YL
1958 show_msr= [x86] show boot-time MSR settings
1959 Format: { <integer> }
1960 Show boot-time (BIOS-initialized) MSR settings.
1961 The parameter means the number of CPUs to show,
1962 for example 1 means boot CPU only.
1963
1da177e4
LT
1964 sim710= [SCSI,HW]
1965 See header of drivers/scsi/sim710.c.
1966
1967 simeth= [IA-64]
1968 simscsi=
a9913044 1969
1da177e4
LT
1970 slram= [HW,MTD]
1971
f0630fff
CL
1972 slub_debug[=options[,slabs]] [MM, SLUB]
1973 Enabling slub_debug allows one to determine the
1974 culprit if slab objects become corrupted. Enabling
1975 slub_debug can create guard zones around objects and
1976 may poison objects when not in use. Also tracks the
1977 last alloc / free. For more information see
1978 Documentation/vm/slub.txt.
c1aee215
CL
1979
1980 slub_max_order= [MM, SLUB]
f0630fff
CL
1981 Determines the maximum allowed order for slabs.
1982 A high setting may cause OOMs due to memory
1983 fragmentation. For more information see
1984 Documentation/vm/slub.txt.
c1aee215
CL
1985
1986 slub_min_objects= [MM, SLUB]
f0630fff
CL
1987 The minimum number of objects per slab. SLUB will
1988 increase the slab order up to slub_max_order to
1989 generate a sufficiently large slab able to contain
1990 the number of objects indicated. The higher the number
1991 of objects the smaller the overhead of tracking slabs
1992 and the less frequently locks need to be acquired.
c1aee215
CL
1993 For more information see Documentation/vm/slub.txt.
1994
1995 slub_min_order= [MM, SLUB]
1996 Determines the mininum page order for slabs. Must be
f0630fff 1997 lower than slub_max_order.
c1aee215
CL
1998 For more information see Documentation/vm/slub.txt.
1999
2000 slub_nomerge [MM, SLUB]
f0630fff 2001 Disable merging of slabs with similar size. May be
c1aee215 2002 necessary if there is some reason to distinguish
f0630fff
CL
2003 allocs to different slabs. Debug options disable
2004 merging on their own.
c1aee215
CL
2005 For more information see Documentation/vm/slub.txt.
2006
1da177e4
LT
2007 smart2= [HW]
2008 Format: <io1>[,<io2>[,...,<io8>]]
2009
cd4f0ef7 2010 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2011 attempt to substitute SMP alternatives once at boot.
2012
d0d4f69b
BH
2013 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2014 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2015 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2016 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2017 smsc-ircc2.ircc_irq= [HW] IRQ line
2018 smsc-ircc2.ircc_dma= [HW] DMA channel
2019 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2020 0: Toshiba Satellite 1800 (GP data pin select)
2021 1: Fast pin select (default)
2022 2: ATC IRMode
2023
1da177e4
LT
2024 snd-ad1816a= [HW,ALSA]
2025
2026 snd-ad1848= [HW,ALSA]
2027
2028 snd-ali5451= [HW,ALSA]
2029
2030 snd-als100= [HW,ALSA]
2031
2032 snd-als4000= [HW,ALSA]
2033
2034 snd-azt2320= [HW,ALSA]
2035
2036 snd-cmi8330= [HW,ALSA]
2037
2038 snd-cmipci= [HW,ALSA]
2039
2040 snd-cs4231= [HW,ALSA]
2041
2042 snd-cs4232= [HW,ALSA]
2043
2044 snd-cs4236= [HW,ALSA]
2045
2046 snd-cs4281= [HW,ALSA]
2047
2048 snd-cs46xx= [HW,ALSA]
2049
2050 snd-dt019x= [HW,ALSA]
2051
2052 snd-dummy= [HW,ALSA]
2053
2054 snd-emu10k1= [HW,ALSA]
2055
2056 snd-ens1370= [HW,ALSA]
2057
2058 snd-ens1371= [HW,ALSA]
2059
2060 snd-es968= [HW,ALSA]
2061
2062 snd-es1688= [HW,ALSA]
2063
2064 snd-es18xx= [HW,ALSA]
2065
2066 snd-es1938= [HW,ALSA]
2067
2068 snd-es1968= [HW,ALSA]
2069
2070 snd-fm801= [HW,ALSA]
2071
2072 snd-gusclassic= [HW,ALSA]
2073
2074 snd-gusextreme= [HW,ALSA]
2075
2076 snd-gusmax= [HW,ALSA]
2077
2078 snd-hdsp= [HW,ALSA]
2079
2080 snd-ice1712= [HW,ALSA]
2081
2082 snd-intel8x0= [HW,ALSA]
2083
2084 snd-interwave= [HW,ALSA]
2085
2086 snd-interwave-stb=
2087 [HW,ALSA]
2088
2089 snd-korg1212= [HW,ALSA]
2090
2091 snd-maestro3= [HW,ALSA]
2092
2093 snd-mpu401= [HW,ALSA]
2094
2095 snd-mtpav= [HW,ALSA]
2096
2097 snd-nm256= [HW,ALSA]
2098
2099 snd-opl3sa2= [HW,ALSA]
2100
2101 snd-opti92x-ad1848=
2102 [HW,ALSA]
2103
2104 snd-opti92x-cs4231=
2105 [HW,ALSA]
2106
2107 snd-opti93x= [HW,ALSA]
2108
2109 snd-pmac= [HW,ALSA]
2110
2111 snd-rme32= [HW,ALSA]
2112
2113 snd-rme96= [HW,ALSA]
2114
2115 snd-rme9652= [HW,ALSA]
2116
2117 snd-sb8= [HW,ALSA]
2118
2119 snd-sb16= [HW,ALSA]
2120
2121 snd-sbawe= [HW,ALSA]
2122
2123 snd-serial= [HW,ALSA]
2124
2125 snd-sgalaxy= [HW,ALSA]
2126
2127 snd-sonicvibes= [HW,ALSA]
2128
2129 snd-sun-amd7930=
2130 [HW,ALSA]
2131
2132 snd-sun-cs4231= [HW,ALSA]
2133
2134 snd-trident= [HW,ALSA]
2135
2136 snd-usb-audio= [HW,ALSA,USB]
2137
2138 snd-via82xx= [HW,ALSA]
2139
2140 snd-virmidi= [HW,ALSA]
2141
2142 snd-wavefront= [HW,ALSA]
2143
2144 snd-ymfpci= [HW,ALSA]
a9913044 2145
9c44bc03
IM
2146 softlockup_panic=
2147 [KNL] Should the soft-lockup detector generate panics.
2148
1da177e4
LT
2149 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2150 See Documentation/sonypi.txt
2151
2152 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2153 See Documentation/serial/specialix.txt.
1da177e4
LT
2154
2155 spia_io_base= [HW,MTD]
2156 spia_fio_base=
2157 spia_pedr=
2158 spia_peddr=
2159
2160 sscape= [HW,OSS]
2161 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2162
1da177e4
LT
2163 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2164 See Documentation/scsi/st.txt.
2165
1da177e4
LT
2166 sti= [PARISC,HW]
2167 Format: <num>
2168 Set the STI (builtin display/keyboard on the HP-PARISC
2169 machines) console (graphic card) which should be used
2170 as the initial boot-console.
2171 See also comment in drivers/video/console/sticore.c.
2172
2173 sti_font= [HW]
2174 See comment in drivers/video/console/sticore.c.
2175
2176 stifb= [HW]
2177 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2178
42a7fc4a
GB
2179 sunrpc.pool_mode=
2180 [NFS]
2181 Control how the NFS server code allocates CPUs to
2182 service thread pools. Depending on how many NICs
2183 you have and where their interrupts are bound, this
2184 option will affect which CPUs will do NFS serving.
2185 Note: this parameter cannot be changed while the
2186 NFS server is running.
2187
2188 auto the server chooses an appropriate mode
2189 automatically using heuristics
2190 global a single global pool contains all CPUs
2191 percpu one pool for each CPU
2192 pernode one pool for each NUMA node (equivalent
2193 to global on non-NUMA machines)
2194
1da177e4 2195 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2196
1da177e4
LT
2197 switches= [HW,M68k]
2198
2199 sym53c416= [HW,SCSI]
2200 See header of drivers/scsi/sym53c416.c.
2201
5d6f647f
IM
2202 sysrq_always_enabled
2203 [KNL]
2204 Ignore sysrq setting - this boot parameter will
2205 neutralize any effect of /proc/sys/kernel/sysrq.
2206 Useful for debugging.
2207
1da177e4
LT
2208 t128= [HW,SCSI]
2209 See header of drivers/scsi/t128.c.
2210
2211 tdfx= [HW,DRM]
2212
77437fd4
DB
2213 test_suspend= [SUSPEND]
2214 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2215 standby suspend) as the system sleep state to briefly
2216 enter during system startup. The system is woken from
2217 this state using a wakeup-capable RTC alarm.
2218
1da177e4
LT
2219 thash_entries= [KNL,NET]
2220 Set number of hash buckets for TCP connection
2221
f8707ec9
LB
2222 thermal.act= [HW,ACPI]
2223 -1: disable all active trip points in all thermal zones
2224 <degrees C>: override all lowest active trip points
2225
c52a7419
LB
2226 thermal.crt= [HW,ACPI]
2227 -1: disable all critical trip points in all thermal zones
22a94d79 2228 <degrees C>: override all critical trip points
c52a7419 2229
f5487145
LB
2230 thermal.nocrt= [HW,ACPI]
2231 Set to disable actions on ACPI thermal zone
2232 critical and hot trip points.
2233
72b33ef8
LB
2234 thermal.off= [HW,ACPI]
2235 1: disable ACPI thermal control
2236
a70cdc52
LB
2237 thermal.psv= [HW,ACPI]
2238 -1: disable all passive trip points
2239 <degrees C>: override all passive trip points to this value
2240
730ff34d
LB
2241 thermal.tzp= [HW,ACPI]
2242 Specify global default ACPI thermal zone polling rate
2243 <deci-seconds>: poll all this frequency
2244 0: no polling (default)
2245
1da177e4
LT
2246 tmscsim= [HW,SCSI]
2247 See comment before function dc390_setup() in
2248 drivers/scsi/tmscsim.c.
2249
2250 tp720= [HW,PS2]
2251
2252 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2253 Format:
2254 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2255
a9913044
RD
2256 turbografx.map[2|3]= [HW,JOY]
2257 TurboGraFX parallel port interface
2258 Format:
2259 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2260 See also Documentation/input/joystick-parport.txt
2261
2262 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2263 See header of drivers/scsi/u14-34f.c.
2264
2265 uart401= [HW,OSS]
2266 Format: <io>,<irq>
2267
2268 uart6850= [HW,OSS]
2269 Format: <io>,<irq>
2270
5f8364b7
AS
2271 uhci-hcd.ignore_oc=
2272 [USB] Ignore overcurrent events (default N).
2273 Some badly-designed motherboards generate lots of
2274 bogus events, for ports that aren't wired to
2275 anything. Set this parameter to avoid log spamming.
2276 Note that genuine overcurrent events won't be
2277 reported either.
2278
e3a61b0a
SA
2279 unknown_nmi_panic
2280 [X86-32,X86-64]
2281 Set unknown_nmi_panic=1 early on boot.
2282
b5e795f8
AS
2283 usbcore.autosuspend=
2284 [USB] The autosuspend time delay (in seconds) used
2285 for newly-detected USB devices (default 2). This
2286 is the time required before an idle device will be
2287 autosuspended. Devices for which the delay is set
eaafbc3a 2288 to a negative value won't be autosuspended at all.
b5e795f8 2289
fd7c519d
JK
2290 usbcore.usbfs_snoop=
2291 [USB] Set to log all usbfs traffic (default 0 = off).
2292
2293 usbcore.blinkenlights=
2294 [USB] Set to cycle leds on hubs (default 0 = off).
2295
2296 usbcore.old_scheme_first=
2297 [USB] Start with the old device initialization
2298 scheme (default 0 = off).
2299
2300 usbcore.use_both_schemes=
2301 [USB] Try the other device initialization scheme
2302 if the first one fails (default 1 = enabled).
2303
2304 usbcore.initial_descriptor_timeout=
2305 [USB] Specifies timeout for the initial 64-byte
2306 USB_REQ_GET_DESCRIPTOR request in milliseconds
2307 (default 5000 = 5.0 seconds).
2308
1da177e4
LT
2309 usbhid.mousepoll=
2310 [USBHID] The interval which mice are to be polled at.
a9913044 2311
200001eb
PJ
2312 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2313 kernel's map of available physical RAM.
2314
cd4f0ef7 2315 vdso= [X86-32,SH,x86-64]
1dbf527c 2316 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2317 vdso=1: enable VDSO (default)
2318 vdso=0: disable VDSO mapping
2319
af65d648
RM
2320 vdso32= [X86-32,X86-64]
2321 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2322 vdso32=1: enable 32-bit VDSO (default)
2323 vdso32=0: disable 32-bit VDSO mapping
2324
d080d397
YI
2325 vector= [IA-64,SMP]
2326 vector=percpu: enable percpu vector domain
2327
1da177e4
LT
2328 video= [FB] Frame buffer configuration
2329 See Documentation/fb/modedb.txt.
2330
cd4f0ef7 2331 vga= [BOOT,X86-32] Select a particular video mode
71cced6e 2332 See Documentation/x86/i386/boot.txt and
a9913044 2333 Documentation/svga.txt.
1da177e4
LT
2334 Use vga=ask for menu.
2335 This is actually a boot loader parameter; the value is
2336 passed to the kernel using a special protocol.
2337
a9913044 2338 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2339 size of <nn>. This can be used to increase the
2340 minimum size (128MB on x86). It can also be used to
2341 decrease the size and leave more room for directly
2342 mapped kernel RAM.
2343
585c3047
PO
2344 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2345 Format: <command>
1da177e4 2346
585c3047
PO
2347 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2348 Format: <command>
2349
2350 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2351 Format: <command>
a9913044 2352
1da177e4
LT
2353 waveartist= [HW,OSS]
2354 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2355
1da177e4
LT
2356 wd33c93= [HW,SCSI]
2357 See header of drivers/scsi/wd33c93.c.
2358
2359 wd7000= [HW,SCSI]
2360 See header of drivers/scsi/wd7000.c.
2361
2362 wdt= [WDT] Watchdog
8dfe9c21 2363 See Documentation/watchdog/wdt.txt.
1da177e4
LT
2364
2365 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2366 xd_geo= See header of drivers/block/xd.c.
2367
2368 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2369 Format:
2370 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2371
a62eaf15
AK
2372 norandmaps Don't use address space randomization
2373 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2374
a9913044 2375______________________________________________________________________
1da177e4
LT
2376
2377TODO:
2378
2379 Add documentation for ALSA options.
2380 Add more DRM drivers.