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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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20Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
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26This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
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33The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
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37
38 ACPI ACPI support is enabled.
c99c108a 39 AGP AGP (Accelerated Graphics Port) is enabled.
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40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
e7ba176b 43 AVR32 AVR32 architecture is enabled.
1da177e4 44 AX25 Appropriate AX.25 support is enabled.
0ae53640 45 BLACKFIN Blackfin architecture is enabled.
a9913044 46 DRM Direct Rendering Management support is enabled.
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47 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
2521f2c2 51 GCOV GCOV profiling is enabled.
1da177e4 52 HW Appropriate hardware is enabled.
1da177e4 53 IA-64 IA-64 architecture is enabled.
6146f0d5 54 IMA Integrity measurement architecture is enabled.
1da177e4 55 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 56 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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57 ISAPNP ISA PnP code is enabled.
58 ISDN Appropriate ISDN support is enabled.
59 JOY Appropriate joystick support is enabled.
fef07aae 60 KVM Kernel Virtual Machine support is enabled.
11ef697b 61 LIBATA Libata driver is enabled
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62 LP Printer support is enabled.
63 LOOP Loopback device support is enabled.
64 M68k M68k architecture is enabled.
65 These options have more detailed description inside of
66 Documentation/m68k/kernel-options.txt.
67 MCA MCA bus support is enabled.
68 MDA MDA console support is enabled.
69 MOUSE Appropriate mouse support is enabled.
309e57df 70 MSI Message Signaled Interrupts (PCI).
c8facbb6 71 MTD MTD (Memory Technology Device) support is enabled.
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72 NET Appropriate network support is enabled.
73 NUMA NUMA support is enabled.
734efb46 74 GENERIC_TIME The generic timeofday code is enabled.
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75 NFS Appropriate NFS support is enabled.
76 OSS OSS sound support is enabled.
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77 PV_OPS A paravirtualized kernel is enabled.
78 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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79 PARISC The PA-RISC architecture is enabled.
80 PCI PCI bus support is enabled.
7f785763 81 PCIE PCI Express support is enabled.
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82 PCMCIA The PCMCIA subsystem is enabled.
83 PNP Plug & Play support is enabled.
84 PPC PowerPC architecture is enabled.
85 PPT Parallel port support is enabled.
86 PS2 Appropriate PS/2 support is enabled.
87 RAM RAM disk support is enabled.
88 S390 S390 architecture is enabled.
89 SCSI Appropriate SCSI support is enabled.
90 A lot of drivers has their options described inside of
91 Documentation/scsi/.
20510f2f 92 SECURITY Different security models are enabled.
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93 SELINUX SELinux support is enabled.
94 SERIAL Serial support is enabled.
e523d93c 95 SH SuperH architecture is enabled.
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96 SMP The kernel is an SMP kernel.
97 SPARC Sparc architecture is enabled.
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98 SWSUSP Software suspend (hibernation) is enabled.
99 SUSPEND System suspend states are enabled.
f38f1d2a 100 FTRACE Function tracing enabled.
1da177e4 101 TS Appropriate touchscreen support is enabled.
d4f373e5 102 UMS USB Mass Storage support is enabled.
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103 USB USB support is enabled.
104 USBHID USB Human Interface Device support is enabled.
105 V4L Video For Linux support is enabled.
106 VGA The VGA console has been enabled.
107 VT Virtual terminal support is enabled.
108 WDT Watchdog support is enabled.
109 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 110 X86-32 X86-32, aka i386 architecture is enabled.
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111 X86-64 X86-64 architecture is enabled.
112 More X86-64 boot options can be found in
71cced6e 113 Documentation/x86/x86_64/boot-options.txt .
c0115606 114 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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115
116In addition, the following text indicates that the option:
117
118 BUGS= Relates to possible processor bugs on the said processor.
119 KNL Is a kernel start-up parameter.
120 BOOT Is a boot loader parameter.
121
122Parameters denoted with BOOT are actually interpreted by the boot
123loader, and have no meaning to the kernel directly.
124Do not modify the syntax of boot loader parameters without extreme
954a8b81 125need or coordination with <Documentation/x86/boot.txt>.
1da177e4 126
5558870b 127There are also arch-specific kernel-parameters not documented here.
71cced6e 128See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 129
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130Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
131a trailing = on the name of any parameter states that that parameter will
132be entered as an environment variable, whereas its absence indicates that
133it will appear as a kernel argument readable via /proc/cmdline by programs
134running once the system is up.
135
9c4751fd 136The number of kernel parameters is not limited, but the length of the
137complete command line (parameters including spaces etc.) is limited to
138a fixed number of characters. This limit depends on the architecture
139and is between 256 and 4096 characters. It is defined in the file
140./include/asm/setup.h as COMMAND_LINE_SIZE.
141
142
6cececfc 143 acpi= [HW,ACPI,X86]
03d926f8 144 Advanced Configuration and Power Interface
af23f573 145 Format: { force | off | ht | strict | noirq | rsdt }
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146 force -- enable ACPI if default was off
147 off -- disable ACPI if default was on
148 noirq -- do not use ACPI for IRQ routing
149 ht -- run only enough ACPI to enable Hyper Threading
a9913044 150 strict -- Be less tolerant of platforms that are not
1da177e4 151 strictly ACPI specification compliant.
237889bf 152 rsdt -- prefer RSDT over (default) XSDT
1da177e4 153
53471121 154 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 155
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156 acpi_apic_instance= [ACPI, IOAPIC]
157 Format: <int>
158 2: use 2nd APIC table, if available
159 1,0: use 1st APIC table
4e381a4f 160 default: 0
a1fdcc0d 161
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162 acpi_backlight= [HW,ACPI]
163 acpi_backlight=vendor
164 acpi_backlight=video
165 If set to vendor, prefer vendor specific driver
166 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
167 of the ACPI video.ko driver.
168
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169 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
170 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 171 Format: <int>
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172 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
173 debug output. Bits in debug_layer correspond to a
174 _COMPONENT in an ACPI source file, e.g.,
175 #define _COMPONENT ACPI_PCI_COMPONENT
176 Bits in debug_level correspond to a level in
177 ACPI_DEBUG_PRINT statements, e.g.,
178 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
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179 The debug_level mask defaults to "info". See
180 Documentation/acpi/debug.txt for more information about
181 debug layers and levels.
a0d84a92 182
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183 Enable processor driver info messages:
184 acpi.debug_layer=0x20000000
185 Enable PCI/PCI interrupt routing info messages:
186 acpi.debug_layer=0x400000
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187 Enable AML "Debug" output, i.e., stores to the Debug
188 object while interpreting AML:
189 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
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190 Enable all messages related to ACPI hardware:
191 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
192
193 Some values produce so much output that the system is
194 unusable. The "log_buf_len" parameter may be useful
195 if you need to capture more output.
f989106c 196
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197 acpi_display_output= [HW,ACPI]
198 acpi_display_output=vendor
199 acpi_display_output=video
200 See above.
201
202 acpi_irq_balance [HW,ACPI]
203 ACPI will balance active IRQs
204 default in APIC mode
205
206 acpi_irq_nobalance [HW,ACPI]
207 ACPI will not move active IRQs (default)
208 default in PIC mode
209
210 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
211 Format: <irq>,<irq>...
212
213 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
214 use by PCI
215 Format: <irq>,<irq>...
216
217 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
218
219 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
220 Format: To spoof as Windows 98: ="Microsoft Windows"
221
222 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
223 acpi_osi="string1" # add string1 -- only one string
224 acpi_osi="!string2" # remove built-in string2
225 acpi_osi= # disable all strings
226
6cececfc 227 acpi_pm_good [X86]
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228 Override the pmtimer bug detection: force the kernel
229 to assume that this machine's pmtimer latches its value
230 and always returns good values.
231
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232 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
233 Format: { level | edge | high | low }
234
235 acpi_serialize [HW,ACPI] force serialization of AML methods
236
237 acpi_skip_timer_override [HW,ACPI]
238 Recognize and ignore IRQ0/pin2 Interrupt Override.
239 For broken nForce2 BIOS resulting in XT-PIC timer.
240
241 acpi_sleep= [HW,ACPI] Sleep options
242 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
d7f0eea9 243 old_ordering, s4_nonvs, sci_force_enable }
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244 See Documentation/power/video.txt for information on
245 s3_bios and s3_mode.
246 s3_beep is for debugging; it makes the PC's speaker beep
247 as soon as the kernel's real-mode entry point is called.
248 s4_nohwsig prevents ACPI hardware signature from being
249 used during resume from hibernation.
250 old_ordering causes the ACPI 1.0 ordering of the _PTS
251 control method, with respect to putting devices into
252 low power states, to be enforced (the ACPI 2.0 ordering
253 of _PTS is used by default).
254 s4_nonvs prevents the kernel from saving/restoring the
255 ACPI NVS memory during hibernation.
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256 sci_force_enable causes the kernel to set SCI_EN directly
257 on resume from S1/S3 (which is against the ACPI spec,
258 but some broken systems don't work without it).
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259
260 acpi_use_timer_override [HW,ACPI]
261 Use timer override. For some broken Nvidia NF5 boards
262 that require a timer override, but don't have HPET
263
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264 acpi_enforce_resources= [ACPI]
265 { strict | lax | no }
266 Check for resource conflicts between native drivers
267 and ACPI OperationRegions (SystemIO and SystemMemory
268 only). IO ports and memory declared in ACPI might be
269 used by the ACPI subsystem in arbitrary AML code and
270 can interfere with legacy drivers.
271 strict (default): access to resources claimed by ACPI
272 is denied; legacy drivers trying to access reserved
273 resources will fail to bind to device using them.
274 lax: access to resources claimed by ACPI is allowed;
275 legacy drivers trying to access reserved resources
276 will bind successfully but a warning message is logged.
277 no: ACPI OperationRegions are not marked as reserved,
278 no further checks are performed.
279
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280 ad1848= [HW,OSS]
281 Format: <io>,<irq>,<dma>,<dma2>,<type>
282
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283 add_efi_memmap [EFI; X86] Include EFI memory map in
284 kernel's map of available physical RAM.
285
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286 advansys= [HW,SCSI]
287 See header of drivers/scsi/advansys.c.
288
289 advwdt= [HW,WDT] Advantech WDT
290 Format: <iostart>,<iostop>
291
292 aedsp16= [HW,OSS] Audio Excel DSP 16
293 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
294 See also header of sound/oss/aedsp16.c.
a9913044 295
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296 agp= [AGP]
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
301
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302 aha152x= [HW,SCSI]
303 See Documentation/scsi/aha152x.txt.
304
305 aha1542= [HW,SCSI]
306 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
307
308 aic7xxx= [HW,SCSI]
309 See Documentation/scsi/aic7xxx.txt.
310
311 aic79xx= [HW,SCSI]
312 See Documentation/scsi/aic79xx.txt.
313
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314 amd_iommu= [HW,X86-84]
315 Pass parameters to the AMD IOMMU driver in the system.
316 Possible values are:
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317 isolate - enable device isolation (each device, as far
318 as possible, will get its own protection
3ce1f93c 319 domain) [default]
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320 share - put every device behind one IOMMU into the
321 same protection domain
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322 fullflush - enable flushing of IO/TLB entries when
323 they are unmapped. Otherwise they are
324 flushed before they will be reused, which
325 is a lot of faster
326
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327 amijoy.map= [HW,JOY] Amiga joystick support
328 Map of devices attached to JOY0DAT and JOY1DAT
329 Format: <a>,<b>
330 See also Documentation/kernel/input/joystick.txt
331
332 analog.map= [HW,JOY] Analog joystick and gamepad support
333 Specifies type or capabilities of an analog joystick
334 connected to one of 16 gameports
335 Format: <type1>,<type2>,..<type16>
336
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337 apc= [HW,SPARC]
338 Power management functions (SPARCstation-4/5 + deriv.)
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339 Format: noidle
340 Disable APC CPU standby support. SPARCstation-Fox does
341 not play well with APC CPU idle - disable it if you have
342 APC and your system crashes randomly.
343
ca1eda2d 344 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
c8facbb6 345 Change the output verbosity whilst booting
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346 Format: { quiet (default) | verbose | debug }
347 Change the amount of debugging information output
348 when initialising the APIC and IO-APIC components.
a9913044 349
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350 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
351 Limit apic dumping. The parameter defines the maximal
352 number of local apics being dumped. Also it is possible
353 to set it to "all" by meaning -- no limit here.
354 Format: { 1 (default) | 2 | ... | all }.
355 The parameter valid if only apic=debug or
356 apic=verbose is specified.
357 Example: apic=debug show_lapic=all
358
1da177e4 359 apm= [APM] Advanced Power Management
71f77055 360 See header of arch/x86/kernel/apm_32.c.
1da177e4 361
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362 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
363 Format: <io>,<irq>,<nodeID>
364
365 ataflop= [HW,M68k]
366
367 atarimouse= [HW,MOUSE] Atari Mouse
368
369 atascsi= [HW,SCSI] Atari SCSI
370
371 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
372 EzKey and similar keyboards
373
374 atkbd.reset= [HW] Reset keyboard during initialization
375
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376 atkbd.set= [HW] Select keyboard code set
377 Format: <int> (2 = AT (default), 3 = PS/2)
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378
379 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
380 keyboards
381
382 atkbd.softraw= [HW] Choose between synthetic and real raw mode
383 Format: <bool> (0 = real, 1 = synthetic (default))
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384
385 atkbd.softrepeat= [HW]
386 Use software keyboard repeat
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387
388 autotest [IA64]
389
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390 baycom_epp= [HW,AX25]
391 Format: <io>,<mode>
a9913044 392
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393 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
394 Format: <io>,<mode>
395 See header of drivers/net/hamradio/baycom_par.c.
396
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397 baycom_ser_fdx= [HW,AX25]
398 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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399 Format: <io>,<irq>,<mode>[,<baud>]
400 See header of drivers/net/hamradio/baycom_ser_fdx.c.
401
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402 baycom_ser_hdx= [HW,AX25]
403 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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404 Format: <io>,<irq>,<mode>
405 See header of drivers/net/hamradio/baycom_ser_hdx.c.
406
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407 boot_delay= Milliseconds to delay each printk during boot.
408 Values larger than 10 seconds (10000) are changed to
409 no delay (0).
410 Format: integer
411
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412 bootmem_debug [KNL] Enable bootmem allocator debug messages.
413
1da177e4 414 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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415 bttv.radio= Most important insmod options are available as
416 kernel args too.
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417 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
418 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
419
420 BusLogic= [HW,SCSI]
421 See drivers/scsi/BusLogic.c, comment before function
422 BusLogic_ParseDriverOptions().
423
424 c101= [NET] Moxa C101 synchronous serial card
425
cd4f0ef7 426 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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427 Sometimes CPU hardware bugs make them report the cache
428 size incorrectly. The kernel will attempt work arounds
429 to fix known problems, but for some CPUs it is not
430 possible to determine what the correct size should be.
431 This option provides an override for these situations.
432
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433 capability.disable=
434 [SECURITY] Disable capabilities. This would normally
435 be used only if an alternative security model is to be
436 configured. Potentially dangerous and should only be
437 used if you are entirely sure of the consequences.
438
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439 ccw_timeout_log [S390]
440 See Documentation/s390/CommonIO for details.
1da177e4 441
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442 cgroup_disable= [KNL] Disable a particular controller
443 Format: {name of the controller(s) to disable}
444 {Currently supported controllers - "memory"}
445
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446 checkreqprot [SELINUX] Set initial checkreqprot flag value.
447 Format: { "0" | "1" }
448 See security/selinux/Kconfig help text.
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449 0 -- check protection applied by kernel (includes
450 any implied execute protection).
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451 1 -- check protection requested by application.
452 Default value is set via a kernel config option.
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453 Value can be changed at runtime via
454 /selinux/checkreqprot.
455
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456 cio_ignore= [S390]
457 See Documentation/s390/CommonIO for details.
458
cd4f0ef7 459 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 460 [Deprecated]
3f6dee9b 461 Forces specified clocksource (if available) to be used
734efb46 462 when calculating gettimeofday(). If specified
3f6dee9b 463 clocksource is not available, it defaults to PIT.
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464 Format: { pit | tsc | cyclone | pmtmr }
465
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466 clocksource= [GENERIC_TIME] Override the default clocksource
467 Format: <string>
468 Override the default clocksource and use the clocksource
469 with the name specified.
470 Some clocksource names to choose from, depending on
471 the platform:
472 [all] jiffies (this is the base, fallback clocksource)
473 [ACPI] acpi_pm
474 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
475 pxa_timer,timer3,32k_counter,timer0_1
476 [AVR32] avr32
cd4f0ef7 477 [X86-32] pit,hpet,tsc,vmi-timer;
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478 scx200_hrt on Geode; cyclone on IBM x440
479 [MIPS] MIPS
480 [PARISC] cr16
481 [S390] tod
482 [SH] SuperH
483 [SPARC64] tick
484 [X86-64] hpet,tsc
485
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486 clearcpuid=BITNUM [X86]
487 Disable CPUID feature X for the kernel. See
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488 arch/x86/include/asm/cpufeature.h for the valid bit
489 numbers. Note the Linux specific bits are not necessarily
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490 stable over kernel options, but the vendor specific
491 ones should be.
492 Also note that user programs calling CPUID directly
493 or using the feature without checking anything
494 will still see it. This just prevents it from
495 being used by the kernel or shown in /proc/cpuinfo.
496 Also note the kernel might malfunction if you disable
497 some critical bits.
498
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499 cmo_free_hint= [PPC] Format: { yes | no }
500 Specify whether pages are marked as being inactive
501 when they are freed. This is used in CMO environments
502 to determine OS memory pressure for page stealing by
503 a hypervisor.
504 Default: yes
505
6cececfc 506 code_bytes [X86] How many bytes of object code to print
a25bd949 507 in an oops report.
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508 Range: 0 - 8192
509 Default: 64
510
1da177e4 511 com20020= [HW,NET] ARCnet - COM20020 chipset
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512 Format:
513 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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514
515 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
516 Format: <io>[,<irq>]
517
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518 com90xx= [HW,NET]
519 ARCnet - COM90xx chipset (memory-mapped buffers)
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520 Format: <io>[,<irq>[,<memstart>]]
521
522 condev= [HW,S390] console device
523 conmode=
a9913044 524
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525 console= [KNL] Output console device and options.
526
527 tty<n> Use the virtual console device <n>.
528
529 ttyS<n>[,options]
f1a1c2dc 530 ttyUSB0[,options]
1da177e4 531 Use the specified serial port. The options are of
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RD
532 the form "bbbbpnf", where "bbbb" is the baud rate,
533 "p" is parity ("n", "o", or "e"), "n" is number of
534 bits, and "f" is flow control ("r" for RTS or
535 omit it). Default is "9600n8".
536
537 See Documentation/serial-console.txt for more
538 information. See
539 Documentation/networking/netconsole.txt for an
540 alternative.
1da177e4 541
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YL
542 uart[8250],io,<addr>[,options]
543 uart[8250],mmio,<addr>[,options]
1da177e4
LT
544 Start an early, polled-mode console on the 8250/16550
545 UART at the specified I/O port or MMIO address,
546 switching to the matching ttyS device later. The
547 options are the same as for ttyS, above.
548
f7511d5f
ST
549 If the device connected to the port is not a TTY but a braille
550 device, prepend "brl," before the device type, for instance
551 console=brl,ttyS0
552 For now, only VisioBraille is supported.
553
f324edc8
DM
554 consoleblank= [KNL] The console blank (screen saver) timeout in
555 seconds. Defaults to 10*60 = 10mins. A value of 0
556 disables the blank timer.
557
4cb0e11b
HK
558 coredump_filter=
559 [KNL] Change the default value for
560 /proc/<pid>/coredump_filter.
561 See also Documentation/filesystems/proc.txt.
562
1da177e4 563 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
564 Format:
565 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 566
dc009d92
EB
567 crashkernel=nn[KMG]@ss[KMG]
568 [KNL] Reserve a chunk of physical memory to
569 hold a kernel to switch to with kexec on panic.
570
fb391599
BW
571 crashkernel=range1:size1[,range2:size2,...][@offset]
572 [KNL] Same as above, but depends on the memory
573 in the running system. The syntax of range is
574 start-[end] where start and end are both
575 a memory unit (amount[KMG]). See also
576 Documentation/kdump/kdump.txt for a example.
577
1da177e4
LT
578 cs89x0_dma= [HW,NET]
579 Format: <dma>
580
581 cs89x0_media= [HW,NET]
582 Format: { rj45 | aui | bnc }
a9913044 583
a9913044 584 dasd= [HW,NET]
1da177e4
LT
585 See header of drivers/s390/block/dasd_devmap.c.
586
587 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
588 (one device per port)
589 Format: <port#>,<type>
590 See also Documentation/input/joystick-parport.txt
591
592 debug [KNL] Enable kernel debugging (events log level).
593
cae2ed9a
IM
594 debug_locks_verbose=
595 [KNL] verbose self-tests
596 Format=<0|1>
597 Print debugging info while doing the locking API
598 self-tests.
599 We default to 0 (no extra messages), setting it to
600 1 will print _a lot_ more information - normally
601 only useful to kernel developers.
602
3ac7fe5a
TG
603 debug_objects [KNL] Enable object debugging
604
3e8ebb5c
KM
605 no_debug_objects
606 [KNL] Disable object debugging
607
d3af01f1
TG
608 debugpat [X86] Enable PAT debugging
609
2d27a966 610 decnet.addr= [HW,NET]
1da177e4
LT
611 Format: <area>[,<node>]
612 See also Documentation/networking/decnet.txt.
613
0cb55ad2
RD
614 default_hugepagesz=
615 [same as hugepagesz=] The size of the default
616 HugeTLB page size. This is the size represented by
617 the legacy /proc/ hugepages APIs, used for SHM, and
618 default size when mounting hugetlbfs filesystems.
619 Defaults to the default architecture's huge page size
620 if not specified.
55ff9780 621
1da177e4
LT
622 dhash_entries= [KNL]
623 Set number of hash buckets for dentry cache.
a9913044 624
1da177e4
LT
625 digi= [HW,SERIAL]
626 IO parameters + enable/disable command.
627
628 digiepca= [HW,SERIAL]
629 See drivers/char/README.epca and
31c00fc1 630 Documentation/serial/digiepca.txt.
1da177e4 631
95ffa243 632 disable_mtrr_cleanup [X86]
95ffa243
YL
633 The kernel tries to adjust MTRR layout from continuous
634 to discrete, to make X server driver able to add WB
0cb55ad2 635 entry later. This parameter disables that.
95ffa243 636
093af8d7 637 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
638 By default the kernel will trim any uncacheable
639 memory out of your available memory pool based on
640 MTRR settings. This parameter disables that behavior,
641 possibly causing your machine to run very slowly.
642
6cececfc 643 disable_timer_pin_1 [X86]
0cb55ad2
RD
644 Disable PIN 1 of APIC timer
645 Can be useful to work around chipset bugs.
646
1da177e4
LT
647 dmasound= [HW,OSS] Sound subsystem buffers
648
0cb55ad2
RD
649 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
650 this option disables the debugging code at boot.
651
652 dma_debug_entries=<number>
653 This option allows to tune the number of preallocated
654 entries for DMA-API debugging code. One entry is
655 required per DMA-API allocation. Use this if the
656 DMA-API debugging code disables itself because the
657 architectural default is too low.
658
1745de5e
JR
659 dma_debug_driver=<driver_name>
660 With this option the DMA-API debugging driver
661 filter feature can be enabled at boot time. Just
662 pass the driver to filter for as the parameter.
663 The filter can be disabled or changed to another
664 driver later using sysfs.
665
1da177e4
LT
666 dscc4.setup= [NET]
667
668 dtc3181e= [HW,SCSI]
669
0cb55ad2
RD
670 dynamic_printk Enables pr_debug()/dev_dbg() calls if
671 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
672 These can also be switched on/off via
673 <debugfs>/dynamic_printk/modules
674
675 earlycon= [KNL] Output early console device and options.
676 uart[8250],io,<addr>[,options]
677 uart[8250],mmio,<addr>[,options]
678 Start an early, polled-mode console on the 8250/16550
679 UART at the specified I/O port or MMIO address.
680 The options are the same as for ttyS, above.
681
6cececfc 682 earlyprintk= [X86,SH,BLACKFIN]
1da177e4
LT
683 earlyprintk=vga
684 earlyprintk=serial[,ttySn[,baudrate]]
ea3acb19 685 earlyprintk=ttySn[,baudrate]
9780bc41 686 earlyprintk=dbgp[debugController#]
1da177e4 687
a9913044 688 Append ",keep" to not disable it when the real console
1da177e4
LT
689 takes over.
690
5c05917e 691 Only vga or serial or usb debug port at a time.
1da177e4
LT
692
693 Currently only ttyS0 and ttyS1 are supported.
694
695 Interaction with the standard serial driver is not
696 very good.
697
698 The VGA output is eventually overwritten by the real
699 console.
700
701 eata= [HW,SCSI]
702
1da177e4 703 edd= [EDD]
8c4dd606 704 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 705
1da177e4
LT
706 eisa_irq_edge= [PARISC,HW]
707 See header of drivers/parisc/eisa.c.
708
cd4f0ef7 709 elanfreq= [X86-32]
1da177e4 710 See comment before function elanfreq_setup() in
71f77055 711 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
712
713 elevator= [IOSCHED]
16ab3adf 714 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
715 See Documentation/block/as-iosched.txt and
716 Documentation/block/deadline-iosched.txt for details.
717
6cececfc 718 elfcorehdr= [IA64,PPC,SH,X86]
a9913044 719 Specifies physical address of start of kernel core
aac04b32
VG
720 image elf header. Generally kexec loader will
721 pass this option to capture kernel.
722 See Documentation/kdump/kdump.txt for details.
1da177e4 723
0cb55ad2
RD
724 enable_mtrr_cleanup [X86]
725 The kernel tries to adjust MTRR layout from continuous
726 to discrete, to make X server driver able to add WB
727 entry later. This parameter enables that.
728
ca1eda2d 729 enable_timer_pin_1 [X86]
0cb55ad2
RD
730 Enable PIN 1 of APIC timer
731 Can be useful to work around chipset bugs
732 (in particular on some ATI chipsets).
733 The kernel tries to set a reasonable default.
734
1da177e4
LT
735 enforcing [SELINUX] Set initial enforcing status.
736 Format: {"0" | "1"}
737 See security/selinux/Kconfig help text.
738 0 -- permissive (log only, no denials).
739 1 -- enforcing (deny and log).
740 Default value is 0.
741 Value can be changed at runtime via /selinux/enforce.
742
1da177e4
LT
743 ether= [HW,NET] Ethernet cards parameters
744 This option is obsoleted by the "netdev=" option, which
745 has equivalent usage. See its documentation for details.
746
747 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
748 Format: <io>[,<irq>]
749
de1ba09b
AM
750 failslab=
751 fail_page_alloc=
752 fail_make_request=[KNL]
753 General fault injection mechanism.
754 Format: <interval>,<probability>,<space>,<times>
755 See also /Documentation/fault-injection/.
756
1da177e4
LT
757 fd_mcs= [HW,SCSI]
758 See header of drivers/scsi/fd_mcs.c.
759
760 fdomain= [HW,SCSI]
761 See header of drivers/scsi/fdomain.c.
762
763 floppy= [HW]
31c00fc1 764 See Documentation/blockdev/floppy.txt.
1da177e4 765
f13ae30e
AC
766 force_pal_cache_flush
767 [IA-64] Avoid check_sal_cache_flush which may hang on
768 buggy SAL_CACHE_FLUSH implementations. Using this
769 parameter will force ia64_sal_cache_flush to call
770 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
771
d9e54076 772 ftrace=[tracer]
2af15d6a 773 [FTRACE] will set and start the specified tracer
d9e54076
PZ
774 as early as possible in order to facilitate early
775 boot debugging.
776
777 ftrace_dump_on_oops
2af15d6a
SR
778 [FTRACE] will dump the trace buffers on oops.
779
780 ftrace_filter=[function-list]
781 [FTRACE] Limit the functions traced by the function
782 tracer at boot up. function-list is a comma separated
783 list of functions. This list can be changed at run
784 time by the set_ftrace_filter file in the debugfs
785 tracing directory.
786
787 ftrace_notrace=[function-list]
788 [FTRACE] Do not trace the functions specified in
789 function-list. This list can be changed at run time
790 by the set_ftrace_notrace file in the debugfs
791 tracing directory.
d9e54076 792
369bc18f
SA
793 ftrace_graph_filter=[function-list]
794 [FTRACE] Limit the top level callers functions traced
795 by the function graph tracer at boot up.
796 function-list is a comma separated list of functions
797 that can be changed at run time by the
798 set_graph_function file in the debugfs tracing directory.
799
1da177e4
LT
800 gamecon.map[2|3]=
801 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
802 support via parallel port (up to 5 devices per port)
803 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
804 See also Documentation/input/joystick-parport.txt
805
806 gamma= [HW,DRM]
807
aaf23042
YL
808 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
809 Format: off | on
810 default: on
811
2521f2c2
PO
812 gcov_persist= [GCOV] When non-zero (default), profiling data for
813 kernel modules is saved and remains accessible via
814 debugfs, even when the module is unloaded/reloaded.
815 When zero, profiling data is discarded and associated
816 debugfs files are removed at module unload time.
817
1da177e4
LT
818 gdth= [HW,SCSI]
819 See header of drivers/scsi/gdth.c.
820
821 gpt [EFI] Forces disk with valid GPT signature but
822 invalid Protective MBR to be treated as GPT.
823
1da177e4
LT
824 gvp11= [HW,SCSI]
825
826 hashdist= [KNL,NUMA] Large hashes allocated during boot
827 are distributed across NUMA nodes. Defaults on
429aa0fc 828 for 64bit NUMA, off otherwise.
a9913044 829 Format: 0 | 1 (for off | on)
1da177e4
LT
830
831 hcl= [IA-64] SGI's Hardware Graph compatibility layer
832
833 hd= [EIDE] (E)IDE hard drive subsystem geometry
834 Format: <cyl>,<head>,<sect>
835
1da177e4
LT
836 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
837 size of <nn>. This works even on boxes that have no
838 highmem otherwise. This also works to reduce highmem
839 size on bigger boxes.
840
54cdfdb4
TG
841 highres= [KNL] Enable/disable high resolution timer mode.
842 Valid parameters: "on", "off"
843 Default: "on"
844
1da177e4
LT
845 hisax= [HW,ISDN]
846 See Documentation/isdn/README.HiSax.
847
0cb55ad2
RD
848 hlt [BUGS=ARM,SH]
849
850 hpet= [X86-32,HPET] option to control HPET usage
851 Format: { enable (default) | disable | force |
852 verbose }
853 disable: disable HPET and use PIT instead
854 force: allow force enabled of undocumented chips (ICH4,
855 VIA, nVidia)
856 verbose: show contents of HPET registers during setup
857
b4718e62
AK
858 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
859 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
860 On x86-64 and powerpc, this option can be specified
861 multiple times interleaved with hugepages= to reserve
862 huge pages of different sizes. Valid pages sizes on
863 x86-64 are 2M (when the CPU supports "pse") and 1G
864 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
865 Note that 1GB pages can only be allocated at boot time
866 using hugepages= and not freed afterwards.
6902aa84 867
555d61d6
HB
868 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
869 terminal devices. Valid values: 0..8
431429ff
HB
870 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
871 If specified, z/VM IUCV HVC accepts connections
872 from listed z/VM user IDs only.
cef7125d 873
3a853fb9 874 i2c_bus= [HW] Override the default board specific I2C bus speed
7954763b
JN
875 or register an additional I2C bus that is not
876 registered from board initialization code.
3a853fb9
JN
877 Format:
878 <bus_id>,<clkrate>
879
36d95739 880 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 881 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
882 i8042.dumbkbd [HW] Pretend that controller can only read data from
883 keyboard and cannot control its state
1da177e4
LT
884 (Don't attempt to blink the leds)
885 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 886 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
887 i8042.noloop [HW] Disable the AUX Loopback command while probing
888 for the AUX port
1da177e4
LT
889 i8042.nomux [HW] Don't check presence of an active multiplexing
890 controller
891 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
892 controllers
893 i8042.panicblink=
894 [HW] Frequency with which keyboard LEDs should blink
895 when kernel panics (default is 0.5 sec)
896 i8042.reset [HW] Reset the controller during init and cleanup
897 i8042.unlock [HW] Unlock (ignore) the keylock
898
899 i810= [HW,DRM]
900
e70c9d5e
DT
901 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
902 indicates that the driver is running on unsupported
903 hardware.
1da177e4
LT
904 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
905 does not match list of supported models.
906 i8k.power_status
907 [HW] Report power status in /proc/i8k
908 (disabled by default)
909 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
910 capability is set.
911
912 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
913 See Documentation/mca.txt.
914
915 icn= [HW,ISDN]
916 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
917
0af80c04
DF
918 ide-core.nodma= [HW] (E)IDE subsystem
919 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
075affcb
BZ
920 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
921 .cdrom .chs .ignore_cable are additional options
1c10e938 922 See Documentation/ide/ide.txt.
1da177e4 923
0cb55ad2
RD
924 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
925 Claim all unknown PCI IDE storage controllers.
926
f039b754 927 idle= [X86]
ada9cfdd
RD
928 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
929 Poll forces a polling idle loop that can slightly
930 improve the performance of waking up a idle CPU, but
931 will use a lot of power and make the system run hot.
932 Not recommended.
933 idle=mwait: On systems which support MONITOR/MWAIT but
934 the kernel chose to not use it because it doesn't save
935 as much power as a normal idle loop, use the
936 MONITOR/MWAIT idle loop anyways. Performance should be
937 the same as idle=poll.
938 idle=halt: Halt is forced to be used for CPU idle.
c1e3b377 939 In such case C2/C3 won't be used again.
ada9cfdd 940 idle=nomwait: Disable mwait for CPU C-states
a9913044 941
79290822
IM
942 ignore_loglevel [KNL]
943 Ignore loglevel setting - this will print /all/
944 kernel messages to the console. Useful for debugging.
945
1da177e4
LT
946 ihash_entries= [KNL]
947 Set number of hash buckets for inode cache.
948
3323eec9
MZ
949 ima_audit= [IMA]
950 Format: { "0" | "1" }
951 0 -- integrity auditing messages. (Default)
952 1 -- enable informational integrity auditing messages.
953
954 ima_hash= [IMA]
a9ed83a5 955 Format: { "sha1" | "md5" }
3323eec9
MZ
956 default: "sha1"
957
5789ba3b
EP
958 ima_tcb [IMA]
959 Load a policy which meets the needs of the Trusted
960 Computing Base. This means IMA will measure all
961 programs exec'd, files mmap'd for exec, and all files
962 opened for read by uid=0.
963
1da177e4
LT
964 in2000= [HW,SCSI]
965 See header of drivers/scsi/in2000.c.
966
967 init= [KNL]
968 Format: <full_path>
969 Run specified binary instead of /sbin/init as init
970 process.
971
972 initcall_debug [KNL] Trace initcalls as they are executed. Useful
973 for working out where the kernel is dying during
974 startup.
975
976 initrd= [BOOT] Specify the location of the initial ramdisk
977
978 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
979 Format: <irq>
980
ba395927 981 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
0cd5c3c8
KM
982 on
983 Enable intel iommu driver.
ba395927
KA
984 off
985 Disable intel iommu driver.
986 igfx_off [Default Off]
987 By default, gfx is mapped as normal device. If a gfx
988 device has a dedicated DMAR unit, the DMAR unit is
989 bypassed by not enabling DMAR with this option. In
990 this case, gfx device will use physical address for
991 DMA.
7d3b03ce
KA
992 forcedac [x86_64]
993 With this option iommu will not optimize to look
994 for io virtual address below 32 bit forcing dual
995 address cycle on pci bus for cards supporting greater
996 than 32 bit addressing. The default is to look
997 for translation below 32 bit and if not available
998 then look in the higher range.
5e0d2a6f 999 strict [Default Off]
1000 With this option on every unmap_single operation will
1001 result in a hardware IOTLB flush operation as opposed
1002 to batching them for performance.
ba395927 1003
0cb55ad2
RD
1004 inttest= [IA64]
1005
1006 iomem= Disable strict checking of access to MMIO memory
1007 strict regions from userspace.
1008 relaxed
1009
1010 iommu= [x86]
1011 off
1012 force
1013 noforce
1014 biomerge
1015 panic
1016 nopanic
1017 merge
1018 nomerge
1019 forcesac
1020 soft
4ed0d3e6 1021 pt [x86, IA64]
0cb55ad2
RD
1022
1023 io7= [HW] IO7 for Marvel based alpha systems
1024 See comment before marvel_specify_io7 in
1025 arch/alpha/kernel/core_marvel.c.
1026
6cececfc 1027 io_delay= [X86] I/O delay method
6e7c4025
IM
1028 0x80
1029 Standard port 0x80 based delay
1030 0xed
1031 Alternate port 0xed based delay (needed on some systems)
b02aae9c 1032 udelay
6e7c4025
IM
1033 Simple two microseconds delay
1034 none
1035 No delay
b02aae9c 1036
1da177e4 1037 ip= [IP_PNP]
dc7a0816 1038 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1039
1040 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
1041 See comment before ip2_setup() in
1042 drivers/char/ip2/ip2base.c.
1da177e4
LT
1043
1044 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1045 See header of drivers/scsi/ips.c.
1046
200803df
AC
1047 irqfixup [HW]
1048 When an interrupt is not handled search all handlers
1049 for it. Intended to get systems with badly broken
1050 firmware running.
1051
1052 irqpoll [HW]
1053 When an interrupt is not handled search all handlers
1054 for it. Also check all handlers each timer
1055 interrupt. Intended to get systems with badly broken
1056 firmware running.
1057
1da177e4 1058 isapnp= [ISAPNP]
a9913044 1059 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
1060
1061 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
1062 Format:
1063 <cpu number>,...,<cpu number>
1064 or
b225d44e
LZ
1065 <cpu number>-<cpu number>
1066 (must be a positive range in ascending order)
22f2e280
DF
1067 or a mixture
1068 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 1069
1da177e4
LT
1070 This option can be used to specify one or more CPUs
1071 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
1072 algorithms. You can move a process onto or off an
1073 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
1074 <cpu number> begins at 0 and the maximum value is
1075 "number of CPUs in system - 1".
1076
1077 This option is the preferred way to isolate CPUs. The
a9913044
RD
1078 alternative -- manually setting the CPU mask of all
1079 tasks in the system -- can cause problems and
1080 suboptimal load balancer performance.
1da177e4 1081
a9913044 1082 iucv= [HW,NET]
1da177e4
LT
1083
1084 js= [HW,JOY] Analog joystick
1085 See Documentation/input/joystick.txt.
1086
0cb55ad2
RD
1087 keepinitrd [HW,ARM]
1088
6cececfc 1089 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
ed7ed365
MG
1090 specifies the amount of memory usable by the kernel
1091 for non-movable allocations. The requested amount is
1092 spread evenly throughout all nodes in the system. The
1093 remaining memory in each node is used for Movable
1094 pages. In the event, a node is too small to have both
1095 kernelcore and Movable pages, kernelcore pages will
1096 take priority and other nodes will have a larger number
1097 of kernelcore pages. The Movable zone is used for the
1098 allocation of pages that may be reclaimed or moved
1099 by the page migration subsystem. This means that
1100 HugeTLB pages may not be allocated from this zone.
1101 Note that allocations like PTEs-from-HighMem still
1102 use the HighMem zone if it exists, and the Normal
1103 zone if it does not.
1104
6cdf6e06
JW
1105 kgdboc= [HW] kgdb over consoles.
1106 Requires a tty driver that supports console polling.
19f59460 1107 (only serial supported for now)
6cdf6e06
JW
1108 Format: <serial_device>[,baud]
1109
9bed90c6
FF
1110 kmac= [MIPS] korina ethernet MAC address.
1111 Configure the RouterBoard 532 series on-chip
1112 Ethernet adapter MAC address.
1113
04f70336
CM
1114 kmemleak= [KNL] Boot-time kmemleak enable/disable
1115 Valid arguments: on, off
1116 Default: on
1117
6cececfc 1118 kstack=N [X86] Print N words from the kernel stack
0cb55ad2
RD
1119 in oops dumps.
1120
fef07aae
AP
1121 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1122 Default is 0 (don't ignore, but inject #GP)
1123
1124 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1125 Default is 1 (enabled)
1126
1127 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1128 Default is 0 (off)
1129
1130 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1131 for all guests.
1132 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1133
1134 kvm-intel.bypass_guest_pf=
1135 [KVM,Intel] Disables bypassing of guest page faults
1136 on Intel chips. Default is 1 (enabled)
1137
1138 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1139 (virtualized MMU) support on capable Intel chips.
1140 Default is 1 (enabled)
1141
1142 kvm-intel.emulate_invalid_guest_state=
1143 [KVM,Intel] Enable emulation of invalid guest states
1144 Default is 0 (disabled)
1145
1146 kvm-intel.flexpriority=
1147 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1148 Default is 1 (enabled)
1149
1150 kvm-intel.unrestricted_guest=
1151 [KVM,Intel] Disable unrestricted guest feature
1152 (virtualized real and unpaged mode) on capable
1153 Intel chips. Default is 1 (enabled)
1154
1155 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1156 feature (tagged TLBs) on capable Intel chips.
1157 Default is 1 (enabled)
1158
1da177e4
LT
1159 l2cr= [PPC]
1160
a78bfbfc
RB
1161 l3cr= [PPC]
1162
cd4f0ef7 1163 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1164 disabled it.
1da177e4 1165
6cececfc 1166 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
ada9cfdd 1167 in C2 power state.
e585bef8 1168
fcb71f6f
FC
1169 libata.dma= [LIBATA] DMA control
1170 libata.dma=0 Disable all PATA and SATA DMA
1171 libata.dma=1 PATA and SATA Disk DMA only
1172 libata.dma=2 ATAPI (CDROM) DMA only
1173 libata.dma=4 Compact Flash DMA only
1174 Combinations also work, so libata.dma=3 enables DMA
1175 for disks and CDROMs, but not CFs.
20308871
MP
1176
1177 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1178 libata.ignore_hpa=0 keep BIOS limits (default)
1179 libata.ignore_hpa=1 ignore limits, using full disk
fcb71f6f 1180
78e70c23
DJ
1181 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1182 when set.
1183 Format: <int>
1184
33267325
TH
1185 libata.force= [LIBATA] Force configurations. The format is comma
1186 separated list of "[ID:]VAL" where ID is
1187 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1188 matching port, link or device. Basically, it matches
1189 the ATA ID string printed on console by libata. If
1190 the whole ID part is omitted, the last PORT and DEVICE
1191 values are used. If ID hasn't been specified yet, the
1192 configuration applies to all ports, links and devices.
1193
1194 If only DEVICE is omitted, the parameter applies to
1195 the port and all links and devices behind it. DEVICE
1196 number of 0 either selects the first device or the
1197 first fan-out link behind PMP device. It does not
1198 select the host link. DEVICE number of 15 selects the
1199 host link and device attached to it.
1200
1201 The VAL specifies the configuration to force. As long
1202 as there's no ambiguity shortcut notation is allowed.
1203 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1204 The following configurations can be forced.
1205
1206 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1207 Any ID with matching PORT is used.
1208
1209 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1210
1211 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1212 udma[/][16,25,33,44,66,100,133] notation is also
1213 allowed.
1214
1215 * [no]ncq: Turn on or off NCQ.
1216
05944bdf
TH
1217 * nohrst, nosrst, norst: suppress hard, soft
1218 and both resets.
1219
33267325
TH
1220 If there are multiple matching configurations changing
1221 the same attribute, the last one is used.
1222
7c4be253
RD
1223 lmb=debug [KNL] Enable lmb debug messages.
1224
1da177e4 1225 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1226 See Documentation/blockdev/ramdisk.txt.
1da177e4 1227
a6b25b67
RD
1228 lockd.nlm_grace_period=P [NFS] Assign grace period.
1229 Format: <integer>
1da177e4 1230
a6b25b67
RD
1231 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1232 Format: <integer>
1233
1234 lockd.nlm_timeout=T [NFS] Assign timeout value.
1235 Format: <integer>
1236
1237 lockd.nlm_udpport=M [NFS] Assign UDP port.
1238 Format: <integer>
1da177e4
LT
1239
1240 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1241 Format: <irq>
1242
1243 loglevel= All Kernel Messages with a loglevel smaller than the
1244 console loglevel will be printed to the console. It can
1245 also be changed with klogd or other programs. The
1246 loglevels are defined as follows:
1247
1248 0 (KERN_EMERG) system is unusable
1249 1 (KERN_ALERT) action must be taken immediately
1250 2 (KERN_CRIT) critical conditions
1251 3 (KERN_ERR) error conditions
1252 4 (KERN_WARNING) warning conditions
1253 5 (KERN_NOTICE) normal but significant condition
1254 6 (KERN_INFO) informational
1255 7 (KERN_DEBUG) debug-level messages
1256
1257 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1258 Format: { n | nk | nM }
1259 n must be a power of two. The default size
1260 is set in the kernel config file.
1da177e4 1261
accaa24c
RD
1262 logo.nologo [FB] Disables display of the built-in Linux logo.
1263 This may be used to provide more screen space for
1264 kernel log messages and is useful when debugging
1265 kernel boot problems.
1266
1da177e4
LT
1267 lp=0 [LP] Specify parallel ports to use, e.g,
1268 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1269 lp=reset first parallel port). 'lp=0' disables the
1270 lp=auto printer driver. 'lp=reset' (which can be
1271 specified in addition to the ports) causes
1272 attached printers to be reset. Using
1273 lp=port1,port2,... specifies the parallel ports
1274 to associate lp devices with, starting with
1275 lp0. A port specification may be 'none' to skip
1276 that lp device, or a parport name such as
1277 'parport0'. Specifying 'lp=auto' instead of a
1278 port specification list means that device IDs
1279 from each port should be examined, to see if
1280 an IEEE 1284-compliant printer is attached; if
1281 so, the driver will manage that printer.
1282 See also header of drivers/char/lp.c.
1283
1284 lpj=n [KNL]
1285 Sets loops_per_jiffy to given constant, thus avoiding
1286 time-consuming boot-time autodetection (up to 250 ms per
1287 CPU). 0 enables autodetection (default). To determine
1288 the correct value for your kernel, boot with normal
1289 autodetection and see what value is printed. Note that
1290 on SMP systems the preset will be applied to all CPUs,
1291 which is likely to cause problems if your CPUs need
1292 significantly divergent settings. An incorrect value
1293 will cause delays in the kernel to be wrong, leading to
1294 unpredictable I/O errors and other breakage. Although
1295 unlikely, in the extreme case this might damage your
1296 hardware.
1297
1298 ltpc= [NET]
1299 Format: <io>,<irq>,<dma>
1300
a9913044
RD
1301 mac5380= [HW,SCSI] Format:
1302 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1303
a9913044
RD
1304 machvec= [IA64] Force the use of a particular machine-vector
1305 (machvec) in a generic kernel.
1306 Example: machvec=hpzx1_swiotlb
1da177e4 1307
3209e70e
WZ
1308 machtype= [Loongson] Share the same kernel image file between different
1309 yeeloong laptop.
1310 Example: machtype=lemote-yeeloong-2f-7inch
1311
0cb55ad2
RD
1312 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1313 than or equal to this physical address is ignored.
1da177e4
LT
1314
1315 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1316 should make use of. maxcpus=n : n >= 0 limits the
1317 kernel to using 'n' processors. n=0 is a special case,
1318 it is equivalent to "nosmp", which also disables
1319 the IO APIC.
1da177e4 1320
0cb55ad2
RD
1321 max_loop= [LOOP] Maximum number of loopback devices that can
1322 be mounted
1323 Format: <1-256>
2b2c3750 1324
a9913044 1325 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1326 Should be between 1 and 2^32-1.
1327
1328 max_report_luns=
a9913044 1329 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1330 Should be between 1 and 16384.
1331
1da177e4
LT
1332 mcatest= [IA-64]
1333
cd4f0ef7 1334 mce [X86-32] Machine Check Exception
1da177e4 1335
71cced6e 1336 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1337
1da177e4
LT
1338 md= [HW] RAID subsystems devices and level
1339 See Documentation/md.txt.
a9913044 1340
1da177e4
LT
1341 mdacon= [MDA]
1342 Format: <first>,<last>
1343 Specifies range of consoles to be captured by the MDA.
a9913044 1344
1da177e4
LT
1345 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1346 Amount of memory to be used when the kernel is not able
1347 to see the whole system memory or for test.
cd4f0ef7 1348 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1349 address space collisions. Without memmap= PCI devices
1350 could be placed at addresses belonging to unused RAM.
1351
cd4f0ef7 1352 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1353 memory.
1354
6902aa84
PM
1355 memchunk=nn[KMG]
1356 [KNL,SH] Allow user to override the default size for
1357 per-device physically contiguous DMA buffers.
1358
6cececfc 1359 memmap=exactmap [KNL,X86] Enable setting of an exact
1da177e4
LT
1360 E820 memory map, as specified by the user.
1361 Such memmap=exactmap lines can be constructed based on
1362 BIOS output or other requirements. See the memmap=nn@ss
1363 option description.
1364
1365 memmap=nn[KMG]@ss[KMG]
1366 [KNL] Force usage of a specific region of memory
1367 Region of memory to be used, from ss to ss+nn.
1368
1369 memmap=nn[KMG]#ss[KMG]
1370 [KNL,ACPI] Mark specific memory as ACPI data.
1371 Region of memory to be used, from ss to ss+nn.
1372
1373 memmap=nn[KMG]$ss[KMG]
1374 [KNL,ACPI] Mark specific memory as reserved.
1375 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1376 Example: Exclude memory from 0x18690000-0x1869ffff
1377 memmap=64K$0x18690000
1378 or
1379 memmap=0x10000$0x18690000
1da177e4 1380
9f077871
JF
1381 memory_corruption_check=0/1 [X86]
1382 Some BIOSes seem to corrupt the first 64k of
1383 memory when doing things like suspend/resume.
1384 Setting this option will scan the memory
1385 looking for corruption. Enabling this will
1386 both detect corruption and prevent the kernel
1387 from using the memory being corrupted.
1388 However, its intended as a diagnostic tool; if
1389 repeatable BIOS-originated corruption always
1390 affects the same memory, you can use memmap=
1391 to prevent the kernel from using that memory.
1392
1393 memory_corruption_check_size=size [X86]
1394 By default it checks for corruption in the low
1395 64k, making this memory unavailable for normal
1396 use. Use this parameter to scan for
1397 corruption in more or less memory.
1398
1399 memory_corruption_check_period=seconds [X86]
1400 By default it checks for corruption every 60
1401 seconds. Use this parameter to check at some
1402 other rate. 0 disables periodic checking.
1403
caadbdce 1404 memtest= [KNL,X86] Enable memtest
c64df707 1405 Format: <integer>
c64df707 1406 default : 0 <disable>
9e5f6cf5
AH
1407 Specifies the number of memtest passes to be
1408 performed. Each pass selects another test
1409 pattern from a given set of patterns. Memtest
1410 fills the memory with this pattern, validates
1411 memory contents and reserves bad memory
1412 regions that are detected.
c64df707 1413
1da177e4
LT
1414 meye.*= [HW] Set MotionEye Camera parameters
1415 See Documentation/video4linux/meye.txt.
1416
8f36881b
AS
1417 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1418 Multi-Function General Purpose Timers on AMD Geode
1419 platforms.
1420
e6c4dc6c
WT
1421 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1422 the BIOS has incorrectly applied a workaround. TinyBIOS
1423 version 0.98 is known to be affected, 0.99 fixes the
1424 problem by letting the user disable the workaround.
1425
1da177e4
LT
1426 mga= [HW,DRM]
1427
1c207f95
RD
1428 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1429 physical address is ignored.
1430
39f45d7b
MP
1431 mini2440= [ARM,HW,KNL]
1432 Format:[0..2][b][c][t]
1433 Default: "0tb"
1434 MINI2440 configuration specification:
1435 0 - The attached screen is the 3.5" TFT
1436 1 - The attached screen is the 7" TFT
1437 2 - The VGA Shield is attached (1024x768)
1438 Leaving out the screen size parameter will not load
1439 the TFT driver, and the framebuffer will be left
1440 unconfigured.
1441 b - Enable backlight. The TFT backlight pin will be
1442 linked to the kernel VESA blanking code and a GPIO
1443 LED. This parameter is not necessary when using the
1444 VGA shield.
1445 c - Enable the s3c camera interface.
1446 t - Reserved for enabling touchscreen support. The
1447 touchscreen support is not enabled in the mainstream
1448 kernel as of 2.6.30, a preliminary port can be found
1449 in the "bleeding edge" mini2440 support kernel at
1450 http://repo.or.cz/w/linux-2.6/mini2440.git
1451
6b74ab97
MG
1452 mminit_loglevel=
1453 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1454 parameter allows control of the logging verbosity for
1455 the additional memory initialisation checks. A value
1456 of 0 disables mminit logging and a level of 4 will
1457 log everything. Information is printed at KERN_DEBUG
1458 so loglevel=8 may also need to be specified.
1459
1da177e4
LT
1460 mousedev.tap_time=
1461 [MOUSE] Maximum time between finger touching and
1462 leaving touchpad surface for touch to be considered
1463 a tap and be reported as a left button click (for
1464 touchpads working in absolute mode only).
1465 Format: <msecs>
1466 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1467 reporting absolute coordinates, such as tablets
1468 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1469 reporting absolute coordinates, such as tablets
1470
6cececfc 1471 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
0cb55ad2
RD
1472 is similar to kernelcore except it specifies the
1473 amount of memory used for migratable allocations.
1474 If both kernelcore and movablecore is specified,
1475 then kernelcore will be at *least* the specified
1476 value but may be more. If movablecore on its own
1477 is specified, the administrator must be careful
1478 that the amount of memory usable for all allocations
1479 is not too small.
1480
1da177e4
LT
1481 mpu401= [HW,OSS]
1482 Format: <io>,<irq>
1483
1484 MTD_Partition= [MTD]
1485 Format: <name>,<region-number>,<size>,<offset>
1486
a9913044
RD
1487 MTD_Region= [MTD] Format:
1488 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1489
1490 mtdparts= [MTD]
c8facbb6 1491 See drivers/mtd/cmdlinepart.c.
1da177e4 1492
5988af23
RH
1493 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1494
1495 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1496
1497 boundary - index of last SLC block on Flex-OneNAND.
1498 The remaining blocks are configured as MLC blocks.
1499 lock - Configure if Flex-OneNAND boundary should be locked.
1500 Once locked, the boundary cannot be changed.
1501 1 indicates lock status, 0 indicates unlock status.
1502
9db829f4
BD
1503 mtdset= [ARM]
1504 ARM/S3C2412 JIVE boot control
1505
1506 See arch/arm/mach-s3c2412/mach-jive.c
1507
1da177e4 1508 mtouchusb.raw_coordinates=
a9913044
RD
1509 [HW] Make the MicroTouch USB driver use raw coordinates
1510 ('y', default) or cooked coordinates ('n')
1da177e4 1511
0cb55ad2 1512 mtrr_chunk_size=nn[KMG] [X86]
19f59460 1513 used for mtrr cleanup. It is largest continuous chunk
0cb55ad2
RD
1514 that could hold holes aka. UC entries.
1515
1516 mtrr_gran_size=nn[KMG] [X86]
1517 Used for mtrr cleanup. It is granularity of mtrr block.
1518 Default is 1.
1519 Large value could prevent small alignment from
1520 using up MTRRs.
1521
1522 mtrr_spare_reg_nr=n [X86]
1523 Format: <integer>
1524 Range: 0,7 : spare reg number
1525 Default : 1
1526 Used for mtrr cleanup. It is spare mtrr entries number.
1527 Set to 2 or more if your graphical card needs more.
1528
1da177e4
LT
1529 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1530
1531 NCR_D700= [HW,SCSI]
1532 See header of drivers/scsi/NCR_D700.c.
1533
1534 ncr5380= [HW,SCSI]
1535
1536 ncr53c400= [HW,SCSI]
1537
1538 ncr53c400a= [HW,SCSI]
1539
1540 ncr53c406a= [HW,SCSI]
1541
1542 ncr53c8xx= [HW,SCSI]
1543
1544 netdev= [NET] Network devices parameters
1545 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1546 Note that mem_start is often overloaded to mean
1547 something different and driver-specific.
a9913044
RD
1548 This usage is only documented in each driver source
1549 file if at all.
1550
58401572
KPO
1551 nf_conntrack.acct=
1552 [NETFILTER] Enable connection tracking flow accounting
1553 0 to disable accounting
1554 1 to enable accounting
1555 Default value depends on CONFIG_NF_CT_ACCT that is
1556 going to be removed in 2.6.29.
1557
1da177e4 1558 nfsaddrs= [NFS]
dc7a0816 1559 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1560
1561 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
dc7a0816 1562 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4 1563
a72b4422
TM
1564 nfs.callback_tcpport=
1565 [NFS] set the TCP port on which the NFSv4 callback
1566 channel should listen.
1567
e571cbf1
TM
1568 nfs.cache_getent=
1569 [NFS] sets the pathname to the program which is used
1570 to update the NFS client cache entries.
1571
1572 nfs.cache_getent_timeout=
1573 [NFS] sets the timeout after which an attempt to
1574 update a cache entry is deemed to have failed.
1575
58df095b
TM
1576 nfs.idmap_cache_timeout=
1577 [NFS] set the maximum lifetime for idmapper cache
1578 entries.
1579
f43bf0be
TM
1580 nfs.enable_ino64=
1581 [NFS] enable 64-bit inode numbers.
1582 If zero, the NFS client will fake up a 32-bit inode
1583 number for the readdir() and stat() syscalls instead
1584 of returning the full 64-bit number.
1585 The default is to return 64-bit inode numbers.
1586
1e1030dc 1587 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
e7ba176b
HS
1588 when a NMI is triggered.
1589 Format: [state][,regs][,debounce][,die]
1590
6cececfc 1591 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
5b9a0e14
CG
1592 Format: [panic,][num]
1593 Valid num: 0,1,2
1594 0 - turn nmi_watchdog off
1595 1 - use the IO-APIC timer for the NMI watchdog
1596 2 - use the local APIC for the NMI watchdog using
0cb55ad2
RD
1597 a performance counter. Note: This will use one
1598 performance counter and the local APIC's performance
1599 vector.
1600 When panic is specified, panic when an NMI watchdog
1601 timeout occurs.
1602 This is useful when you use a panic=... timeout and
1603 need the box quickly up again.
5b9a0e14
CG
1604 Instead of 1 and 2 it is possible to use the following
1605 symbolic names: lapic and ioapic
1606 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1da177e4 1607
bff38771
AV
1608 netpoll.carrier_timeout=
1609 [NET] Specifies amount of time (in seconds) that
1610 netpoll should wait for a carrier. By default netpoll
1611 waits 4 seconds.
1612
cd4f0ef7 1613 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1614 emulation library even if a 387 maths coprocessor
1615 is present.
1616
0cb55ad2
RD
1617 no_console_suspend
1618 [HW] Never suspend the console
1619 Disable suspending of consoles during suspend and
1620 hibernate operations. Once disabled, debugging
1621 messages can reach various consoles while the rest
1622 of the system is being put to sleep (ie, while
1623 debugging driver suspend/resume hooks). This may
1624 not work reliably with all consoles, but is known
1625 to work with serial and VGA consoles.
1626
c1aee215
CL
1627 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1628 caches in the slab allocator. Saves per-node memory,
1629 but will impact performance.
3395ee05 1630
a9913044
RD
1631 noalign [KNL,ARM]
1632
1da177e4
LT
1633 noapic [SMP,APIC] Tells the kernel to not make use of any
1634 IOAPICs that may be present in the system.
1635
1da177e4
LT
1636 nobats [PPC] Do not use BATs for mapping kernel lowmem
1637 on "Classic" PPC cores.
1638
1639 nocache [ARM]
a9913044 1640
0cb55ad2
RD
1641 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1642
163ecdff
SN
1643 nodelayacct [KNL] Disable per-task delay accounting
1644
1da177e4
LT
1645 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1646
6902aa84
PM
1647 nodsp [SH] Disable hardware DSP at boot time.
1648
6cececfc 1649 noefi [X86] Disable EFI runtime services support.
8b2cb7a8 1650
1da177e4
LT
1651 noexec [IA-64]
1652
6cececfc 1653 noexec [X86]
f5a1b191 1654 On X86-32 available only on PAE configured kernels.
1da177e4 1655 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1656 noexec=off: disable non-executable mappings
1657
1658 noexec32 [X86-64]
1659 This affects only 32-bit executables.
1660 noexec32=on: enable non-executable mappings (default)
1661 read doesn't imply executable mappings
1662 noexec32=off: disable non-executable mappings
1663 read implies executable mappings
1da177e4 1664
6902aa84
PM
1665 nofpu [SH] Disable hardware FPU at boot time.
1666
cd4f0ef7 1667 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1668 register save and restore. The kernel will only save
1669 legacy floating-point registers on task switch.
1da177e4 1670
0c752a93
SS
1671 noxsave [BUGS=X86] Disables x86 extended register state save
1672 and restore using xsave. The kernel will fallback to
1673 enabling legacy floating-point and sse state.
1674
01a24d2b
PZ
1675 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1676 wfi(ARM) instruction doesn't work correctly and not to
1677 use it. This is also useful when using JTAG debugger.
a9913044 1678
cd4f0ef7 1679 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1680 instruction doesn't work correctly and not to
1681 use it.
1682
1f29fae2
SH
1683 no_file_caps Tells the kernel not to honor file capabilities. The
1684 only way then for a file to be executed with privilege
1685 is to be setuid root or executed by root.
1686
1da177e4
LT
1687 nohalt [IA-64] Tells the kernel not to use the power saving
1688 function PAL_HALT_LIGHT when idle. This increases
1689 power-consumption. On the positive side, it reduces
1690 interrupt wake-up latency, which may improve performance
1691 in certain environments such as networked servers or
1692 real-time systems.
1693
79bf2bb3
TG
1694 nohz= [KNL] Boottime enable/disable dynamic ticks
1695 Valid arguments: on, off
1696 Default: on
1697
eeee7853
PM
1698 noiotrap [SH] Disables trapped I/O port accesses.
1699
cd4f0ef7 1700 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1701 disable unhandled interrupt sources.
1702
6cececfc 1703 no_timer_check [X86,APIC] Disables the code which tests for
8542b200
ZA
1704 broken timer IRQ sources.
1705
1da177e4
LT
1706 noisapnp [ISAPNP] Disables ISA PnP code.
1707
1708 noinitrd [RAM] Tells the kernel not to load any configured
1709 initial RAM disk.
1710
03ea8155
WH
1711 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1712 remapping.
1713
1da177e4
LT
1714 nointroute [IA-64]
1715
0aa366f3
TL
1716 nojitter [IA64] Disables jitter checking for ITC timers.
1717
cd4f0ef7 1718 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1719
cd4f0ef7 1720 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1721
1da177e4
LT
1722 noltlbs [PPC] Do not use large page/tlb entries for kernel
1723 lowmem mapping on PPC40x.
1724
312f1f01
H
1725 nomca [IA-64] Disable machine check abort handling
1726
cd4f0ef7 1727 nomce [X86-32] Machine Check Exception
abe37e5a 1728
83d7384f
AS
1729 nomfgpt [X86-32] Disable Multi-Function General Purpose
1730 Timer usage (for AMD Geode machines).
1731
0cb55ad2
RD
1732 norandmaps Don't use address space randomization. Equivalent to
1733 echo 0 > /proc/sys/kernel/randomize_va_space
1734
cd4f0ef7 1735 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1736
cd4f0ef7 1737 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1738 with UP alternatives
1739
1da177e4
LT
1740 noresidual [PPC] Don't use residual data on PReP machines.
1741
a9913044
RD
1742 noresume [SWSUSP] Disables resume and restores original swap
1743 space.
1744
1da177e4
LT
1745 no-scroll [VGA] Disables scrollback.
1746 This is required for the Braillex ib80-piezo Braille
1747 reader made by F.H. Papenmeier (Germany).
1748
1749 nosbagart [IA-64]
1750
cd4f0ef7 1751 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1752
61ec7567
LB
1753 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1754 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1755
97842216
DJ
1756 nosoftlockup [KNL] Disable the soft-lockup detector.
1757
c077719b 1758 noswapaccount [KNL] Disable accounting of swap in memory resource
21acb9ca 1759 controller. (See Documentation/cgroups/memory.txt)
c077719b 1760
1da177e4
LT
1761 nosync [HW,M68K] Disables sync negotiation for all devices.
1762
cd4f0ef7 1763 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1764
1765 nousb [USB] Disable the USB subsystem
1766
1767 nowb [ARM]
a9913044 1768
2b2fd87a
WH
1769 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1770
a6c75b86
FY
1771 nptcg= [IA64] Override max number of concurrent global TLB
1772 purges which is reported from either PAL_VM_SUMMARY or
1773 SAL PALO.
1774
2b633e3f
YL
1775 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1776 could support. nr_cpus=n : n >= 1 limits the kernel to
1777 supporting 'n' processors. Later in runtime you can not
1778 use hotplug cpu feature to put more cpu back to online.
1779 just like you compile the kernel NR_CPUS=n
1780
0cb55ad2
RD
1781 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1782
f0c0b2b8
KH
1783 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1784 one of ['zone', 'node', 'default'] can be specified
1785 This can be set from sysctl after boot.
1786 See Documentation/sysctl/vm.txt for details.
1787
7c4be253
RD
1788 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1789 See Documentation/debugging-via-ohci1394.txt for more
1790 info.
1791
3ef0e1f8
AS
1792 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1793 Rather than timing out after 20 ms if an EC
1794 command is not properly ACKed, override the length
1795 of the timeout. We have interrupts disabled while
1796 waiting for the ACK, so if this is set too high
1797 interrupts *may* be lost!
1798
15ac7afe
TL
1799 omap_mux= [OMAP] Override bootloader pin multiplexing.
1800 Format: <mux_mode0.mode_name=value>...
1801 For example, to override I2C bus2:
1802 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1803
1da177e4
LT
1804 opl3= [HW,OSS]
1805 Format: <io>
1806
1da177e4
LT
1807 oprofile.timer= [HW]
1808 Use timer interrupt instead of performance counters
1809
7e4e0bd5
RR
1810 oprofile.cpu_type= Force an oprofile cpu type
1811 This might be useful if you have an older oprofile
1812 userland or if you want common events.
8d7ff4f2
RR
1813 Format: { arch_perfmon }
1814 arch_perfmon: [X86] Force use of architectural
7e4e0bd5
RR
1815 perfmon on Intel CPUs instead of the
1816 CPU specific event set.
1dcdb5a9 1817
1da177e4
LT
1818 osst= [HW,SCSI] SCSI Tape Driver
1819 Format: <buffer_size>,<write_threshold>
1820 See also Documentation/scsi/st.txt.
1821
1822 panic= [KNL] Kernel behaviour on panic
1823 Format: <timeout>
1824
1825 parkbd.port= [HW] Parallel port number the keyboard adapter is
1826 connected to, default is 0.
1827 Format: <parport#>
1828 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1829 0 for XT, 1 for AT (default is AT).
a9913044
RD
1830 Format: <mode>
1831
1832 parport= [HW,PPT] Specify parallel ports. 0 disables.
1833 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1834 Use 'auto' to force the driver to use any
1835 IRQ/DMA settings detected (the default is to
1836 ignore detected IRQ/DMA settings because of
1837 possible conflicts). You can specify the base
1838 address, IRQ, and DMA settings; IRQ and DMA
1839 should be numbers, or 'auto' (for using detected
1840 settings on that particular port), or 'nofifo'
1841 (to avoid using a FIFO even if it is detected).
1842 Parallel ports are assigned in the order they
1843 are specified on the command line, starting
1844 with parport0.
1845
1846 parport_init_mode= [HW,PPT]
1847 Configure VIA parallel port to operate in
1848 a specific mode. This is necessary on Pegasos
1849 computer where firmware has no options for setting
1850 up parallel port mode and sets it to spp.
1851 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1852 Format: [spp|ps2|epp|ecp|ecpepp]
1853
a9913044
RD
1854 pas2= [HW,OSS] Format:
1855 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1856
1da177e4
LT
1857 pas16= [HW,SCSI]
1858 See header of drivers/scsi/pas16.c.
1859
dd287796
AM
1860 pause_on_oops=
1861 Halt all CPUs after the first oops has been printed for
1862 the specified number of seconds. This is to be used if
1863 your oopses keep scrolling off the screen.
1864
1da177e4
LT
1865 pcbit= [HW,ISDN]
1866
1867 pcd. [PARIDE]
1868 See header of drivers/block/paride/pcd.c.
31c00fc1 1869 See also Documentation/blockdev/paride.txt.
1da177e4 1870
a9913044 1871 pci=option[,option...] [PCI] various PCI subsystem options:
1cc0ca26
BH
1872 earlydump [X86] dump PCI config space before the kernel
1873 changes anything
c0115606 1874 off [X86] don't probe for the PCI bus
cd4f0ef7 1875 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1876 the hardware directly. Use this if your machine
1877 has a non-standard PCI host bridge.
cd4f0ef7 1878 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1879 hardware access methods are allowed. Use this
1880 if you experience crashes upon bootup and you
1881 suspect they are caused by the BIOS.
c0115606 1882 conf1 [X86] Force use of PCI Configuration
a9913044 1883 Mechanism 1.
c0115606 1884 conf2 [X86] Force use of PCI Configuration
a9913044 1885 Mechanism 2.
7f785763
RD
1886 noaer [PCIE] If the PCIEAER kernel config parameter is
1887 enabled, this kernel boot option can be used to
1888 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1889 nodomains [PCI] Disable support for multiple PCI
1890 root domains (aka PCI segments, in ACPI-speak).
6cececfc 1891 nommconf [X86] Disable use of MMCONFIG for PCI
61be6d66 1892 Configuration
12983077
AH
1893 check_enable_amd_mmconf [X86] check for and enable
1894 properly configured MMIO access to PCI
1895 config space on AMD family 10h CPU
309e57df
MW
1896 nomsi [MSI] If the PCI_MSI kernel config parameter is
1897 enabled, this kernel boot option can be used to
1898 disable the use of MSI interrupts system-wide.
a9322f64
SA
1899 noioapicquirk [APIC] Disable all boot interrupt quirks.
1900 Safety option to keep boot IRQs enabled. This
1901 should never be necessary.
9197979b
SA
1902 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1903 primary IO-APIC for bridges that cannot disable
1904 boot IRQs. This fixes a source of spurious IRQs
1905 when the system masks IRQs.
41b9eb26
SA
1906 noioapicreroute [APIC] Disable workaround that uses the
1907 boot IRQ equivalent of an IRQ that connects to
1908 a chipset where boot IRQs cannot be disabled.
1909 The opposite of ioapicreroute.
cd4f0ef7 1910 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1911 routing table. These calls are known to be buggy
1912 on several machines and they hang the machine
1913 when used, but on other computers it's the only
1914 way to get the interrupt routing table. Try
1915 this option if the kernel is unable to allocate
1916 IRQs or discover secondary PCI buses on your
1917 motherboard.
c0115606 1918 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1919 Use with caution as certain devices share
1920 address decoders between ROMs and other
1921 resources.
c0115606 1922 norom [X86] Do not assign address space to
bb71ad88
GH
1923 expansion ROMs that do not already have
1924 BIOS assigned address ranges.
c0115606 1925 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1926 assigned automatically to PCI devices. You can
1927 make the kernel exclude IRQs of your ISA cards
1928 this way.
c0115606 1929 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1930 of the PIRQ table (normally generated
1931 by the BIOS) if it is outside the
1932 F0000h-100000h range.
c0115606 1933 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1934 useful if the kernel is unable to find your
1935 secondary buses and you want to tell it
1936 explicitly which ones they are.
c0115606 1937 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1938 numbers ourselves, overriding
1939 whatever the firmware may have done.
c0115606 1940 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1941 in the BIOS $PIR table. This is needed on
1942 some systems with broken BIOSes, notably
1943 some HP Pavilion N5400 and Omnibook XE3
1944 notebooks. This will have no effect if ACPI
1945 IRQ routing is enabled.
c0115606 1946 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1947 or for PCI scanning.
236e946b 1948 use_crs [X86] Use _CRS for PCI resource
62f420f8 1949 allocation.
a9913044
RD
1950 routeirq Do IRQ routing for all PCI devices.
1951 This is normally done in pci_enable_device(),
1952 so this option is a temporary workaround
1953 for broken drivers that don't call it.
13a6ddb0
YL
1954 skip_isa_align [X86] do not align io start addr, so can
1955 handle more pci cards
a9913044
RD
1956 firmware [ARM] Do not re-enumerate the bus but instead
1957 just use the configuration from the
1958 bootloader. This is currently used on
1959 IXP2000 systems where the bus has to be
1960 configured a certain way for adjunct CPUs.
0637a70a
AK
1961 noearly [X86] Don't do any early type 1 scanning.
1962 This might help on some broken boards which
1963 machine check when some devices' config space
1964 is read. But various workarounds are disabled
1965 and some IOMMU drivers will not work.
6b4b78fe
MD
1966 bfsort Sort PCI devices into breadth-first order.
1967 This sorting is done to get a device
1968 order compatible with older (<= 2.4) kernels.
1969 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1970 cbiosize=nn[KMG] The fixed amount of bus space which is
1971 reserved for the CardBus bridge's IO window.
1972 The default value is 256 bytes.
1973 cbmemsize=nn[KMG] The fixed amount of bus space which is
1974 reserved for the CardBus bridge's memory
1975 window. The default value is 64 megabytes.
32a9a682
YS
1976 resource_alignment=
1977 Format:
1978 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1979 Specifies alignment and device to reassign
1980 aligned memory resources.
1981 If <order of align> is not specified,
1982 PAGE_SIZE is used as alignment.
1983 PCI-PCI bridge can be specified, if resource
1984 windows need to be expanded.
43c16408
AP
1985 ecrc= Enable/disable PCIe ECRC (transaction layer
1986 end-to-end CRC checking).
1987 bios: Use BIOS/firmware settings. This is the
1988 the default.
1989 off: Turn ECRC off
1990 on: Turn ECRC on.
6b4b78fe 1991
e5665a45
CE
1992 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1993 Management.
1994 off Disable ASPM.
1995 force Enable ASPM even on devices that claim not to support it.
1996 WARNING: Forcing ASPM on may cause system lockups.
1997
1da177e4
LT
1998 pcmv= [HW,PCMCIA] BadgePAD 4
1999
2000 pd. [PARIDE]
31c00fc1 2001 See Documentation/blockdev/paride.txt.
1da177e4
LT
2002
2003 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2004 boot time.
2005 Format: { 0 | 1 }
2006 See arch/parisc/kernel/pdc_chassis.c
2007
f58dc01b 2008 percpu_alloc= Select which percpu first chunk allocator to use.
e933a73f
TH
2009 Currently supported values are "embed" and "page".
2010 Archs may support subset or none of the selections.
2011 See comments in mm/percpu.c for details on each
2012 allocator. This parameter is primarily for debugging
2013 and performance comparison.
fa8a7094 2014
1da177e4 2015 pf. [PARIDE]
31c00fc1 2016 See Documentation/blockdev/paride.txt.
1da177e4
LT
2017
2018 pg. [PARIDE]
31c00fc1 2019 See Documentation/blockdev/paride.txt.
1da177e4
LT
2020
2021 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 2022 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
2023
2024 plip= [PPT,NET] Parallel port network link
2025 Format: { parport<nr> | timid | 0 }
2026 See also Documentation/parport.txt.
2027
de32a243
TG
2028 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2029 Override pmtimer IOPort with a hex value.
2030 e.g. pmtmr=0x508
2031
97ef062b
BH
2032 pnp.debug [PNP]
2033 Enable PNP debug messages. This depends on the
2034 CONFIG_PNP_DEBUG_MESSAGES option.
2035
1da177e4
LT
2036 pnpacpi= [ACPI]
2037 { off }
2038
2039 pnpbios= [ISAPNP]
2040 { on | off | curr | res | no-curr | no-res }
2041
2042 pnp_reserve_irq=
2043 [ISAPNP] Exclude IRQs for the autoconfiguration
2044
2045 pnp_reserve_dma=
2046 [ISAPNP] Exclude DMAs for the autoconfiguration
2047
2048 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 2049 Ranges are in pairs (I/O port base and size).
1da177e4
LT
2050
2051 pnp_reserve_mem=
a9913044
RD
2052 [ISAPNP] Exclude memory regions for the
2053 autoconfiguration.
1da177e4
LT
2054 Ranges are in pairs (memory base and size).
2055
4af94f39
RD
2056 ports= [IP_VS_FTP] IPVS ftp helper module
2057 Default is 21.
2058 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2059 may be specified.
2060 Format: <port>,<port>....
2061
45807a1d
IM
2062 print-fatal-signals=
2063 [KNL] debug: print fatal signals
f84d49b2
NO
2064
2065 If enabled, warn about various signal handling
2066 related application anomalies: too many signals,
2067 too many POSIX.1 timers, fatal signals causing a
2068 coredump - etc.
2069
2070 If you hit the warning due to signal overflow,
2071 you might want to try "ulimit -i unlimited".
2072
45807a1d
IM
2073 default: off.
2074
e84845c4
RD
2075 printk.time= Show timing data prefixed to each printk message line
2076 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2077
0cb55ad2
RD
2078 processor.max_cstate= [HW,ACPI]
2079 Limit processor to maximum C-state
2080 max_cstate=9 overrides any DMI blacklist limit.
2081
2082 processor.nocst [HW,ACPI]
2083 Ignore the _CST method to determine C-states,
2084 instead using the legacy FADT method
2085
1da177e4 2086 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
2087 Format: [schedule,]<number>
2088 Param: "schedule" - profile schedule points.
2089 Param: <number> - step/bucket size as a power of 2 for
2090 statistical time based profiling.
b3da2a73
MG
2091 Param: "sleep" - profile D-state sleeping (millisecs).
2092 Requires CONFIG_SCHEDSTATS
c0fe2e69 2093 Param: "kvm" - profile VM exits.
1da177e4 2094
1da177e4
LT
2095 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2096 before loading.
31c00fc1 2097 See Documentation/blockdev/ramdisk.txt.
1da177e4 2098
a9913044
RD
2099 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2100 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
2101 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2102 per second.
a9913044
RD
2103 psmouse.resetafter= [HW,MOUSE]
2104 Try to reset the device after so many bad packets
1da177e4
LT
2105 (0 = never).
2106 psmouse.resolution=
2107 [HW,MOUSE] Set desired mouse resolution, in dpi.
2108 psmouse.smartscroll=
a9913044 2109 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
2110 0 = disabled, 1 = enabled (default).
2111
2112 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
2113 Format:
2114 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
2115
2116 pt. [PARIDE]
31c00fc1 2117 See Documentation/blockdev/paride.txt.
1da177e4 2118
dc8c8587
KS
2119 pty.legacy_count=
2120 [KNL] Number of legacy pty's. Overwrites compiled-in
2121 default number.
2122
7d2c502f 2123 quiet [KNL] Disable most log messages
a9913044 2124
1da177e4
LT
2125 r128= [HW,DRM]
2126
2127 raid= [HW,RAID]
2128 See Documentation/md.txt.
2129
a9913044 2130 ramdisk_blocksize= [RAM]
31c00fc1 2131 See Documentation/blockdev/ramdisk.txt.
a9913044 2132
1da177e4 2133 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 2134 See Documentation/blockdev/ramdisk.txt.
1da177e4 2135
24aaef8d
RD
2136 rcupdate.blimit= [KNL,BOOT]
2137 Set maximum number of finished RCU callbacks to process
2138 in one batch.
21a1ea9e 2139
24aaef8d
RD
2140 rcupdate.qhimark= [KNL,BOOT]
2141 Set threshold of queued
21a1ea9e
DS
2142 RCU callbacks over which batch limiting is disabled.
2143
24aaef8d
RD
2144 rcupdate.qlowmark= [KNL,BOOT]
2145 Set threshold of queued RCU callbacks below which
2146 batch limiting is re-enabled.
21a1ea9e 2147
ffdfc409
OJ
2148 rdinit= [KNL]
2149 Format: <full_path>
2150 Run specified binary instead of /init from the ramdisk,
2151 used for early userspace startup. See initrd.
2152
cd4f0ef7 2153 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 2154 Format: <reboot_mode>[,<reboot_mode2>[,...]]
ecb08d81 2155 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 2156
46b6d94e
PJ
2157 relax_domain_level=
2158 [KNL, SMP] Set scheduler's default relax_domain_level.
21acb9ca 2159 See Documentation/cgroups/cpusets.txt.
46b6d94e 2160
1da177e4
LT
2161 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2162
cd4f0ef7 2163 reservetop= [X86-32]
461a9aff
ZA
2164 Format: nn[KMG]
2165 Reserves a hole at the top of the kernel virtual
2166 address space.
2167
7e96287d
VG
2168 reset_devices [KNL] Force drivers to reset the underlying device
2169 during initialization.
2170
a9913044
RD
2171 resume= [SWSUSP]
2172 Specify the partition device for software suspend
1da177e4 2173
ecbd0da1
RW
2174 resume_offset= [SWSUSP]
2175 Specify the offset from the beginning of the partition
2176 given by "resume=" at which the swap header is located,
2177 in <PAGE_SIZE> units (needed only for swap files).
2178 See Documentation/power/swsusp-and-swap-files.txt
2179
0a7b35cb
MN
2180 retain_initrd [RAM] Keep initrd memory after extraction
2181
1da177e4
LT
2182 rhash_entries= [KNL,NET]
2183 Set number of hash buckets for route cache
2184
2185 riscom8= [HW,SERIAL]
2186 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2187
2188 ro [KNL] Mount root device read-only on boot
2189
2190 root= [KNL] Root filesystem
2191
2192 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2193 mount the root filesystem
2194
2195 rootflags= [KNL] Set root filesystem mount option string
2196
2197 rootfstype= [KNL] Set root filesystem type
2198
cc1ed754
PO
2199 rootwait [KNL] Wait (indefinitely) for root device to show up.
2200 Useful for devices that are detected asynchronously
2201 (e.g. USB and MMC devices).
2202
1da177e4
LT
2203 rw [KNL] Mount root device read-write on boot
2204
2205 S [KNL] Run init in single mode
2206
2207 sa1100ir [NET]
2208 See drivers/net/irda/sa1100_ir.c.
2209
1da177e4 2210 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 2211
f6630114
MT
2212 sched_debug [KNL] Enables verbose scheduler debug messages.
2213
1da177e4
LT
2214 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2215 Format: <io>[,<timeout>[,<isapnp>]]
2216
2217 scsi_debug_*= [SCSI]
2218 See drivers/scsi/scsi_debug.c.
2219
2220 scsi_default_dev_flags=
2221 [SCSI] SCSI default device flags
2222 Format: <integer>
2223
2224 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2225 Format: <vendor>:<model>:<flags>
2226 (flags are integer value)
2227
6af6632a
RD
2228 scsi_logging_level= [SCSI] a bit mask of logging levels
2229 See drivers/scsi/scsi_logging.h for bits. Also
2230 settable via sysctl at dev.scsi.logging_level
2231 (/proc/sys/dev/scsi/logging_level).
2232 There is also a nice 'scsi_logging_level' script in the
2233 S390-tools package, available for download at
2234 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 2235
3e082a91
MW
2236 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2237 discovered. async scans them in kernel threads,
2238 allowing boot to proceed. none ignores them, expecting
2239 user space to do the scan.
2240
0cb55ad2
RD
2241 security= [SECURITY] Choose a security module to enable at boot.
2242 If this boot parameter is not specified, only the first
2243 security module asking for security registration will be
2244 loaded. An invalid security module name will be treated
2245 as if no module has been chosen.
2246
2247 selinux= [SELINUX] Disable or enable SELinux at boot time.
1da177e4
LT
2248 Format: { "0" | "1" }
2249 See security/selinux/Kconfig help text.
2250 0 -- disable.
2251 1 -- enable.
2252 Default value is set via kernel config option.
2253 If enabled at boot time, /selinux/disable can be used
2254 later to disable prior to initial policy load.
2255
cd4f0ef7 2256 serialnumber [BUGS=X86-32]
1da177e4 2257
1da177e4
LT
2258 shapers= [NET]
2259 Maximal number of shapers.
a9913044 2260
b05f78f5
YL
2261 show_msr= [x86] show boot-time MSR settings
2262 Format: { <integer> }
2263 Show boot-time (BIOS-initialized) MSR settings.
2264 The parameter means the number of CPUs to show,
2265 for example 1 means boot CPU only.
2266
1da177e4
LT
2267 sim710= [SCSI,HW]
2268 See header of drivers/scsi/sim710.c.
2269
2270 simeth= [IA-64]
2271 simscsi=
a9913044 2272
1da177e4
LT
2273 slram= [HW,MTD]
2274
f0630fff
CL
2275 slub_debug[=options[,slabs]] [MM, SLUB]
2276 Enabling slub_debug allows one to determine the
2277 culprit if slab objects become corrupted. Enabling
2278 slub_debug can create guard zones around objects and
2279 may poison objects when not in use. Also tracks the
2280 last alloc / free. For more information see
2281 Documentation/vm/slub.txt.
c1aee215
CL
2282
2283 slub_max_order= [MM, SLUB]
f0630fff
CL
2284 Determines the maximum allowed order for slabs.
2285 A high setting may cause OOMs due to memory
2286 fragmentation. For more information see
2287 Documentation/vm/slub.txt.
c1aee215
CL
2288
2289 slub_min_objects= [MM, SLUB]
f0630fff
CL
2290 The minimum number of objects per slab. SLUB will
2291 increase the slab order up to slub_max_order to
2292 generate a sufficiently large slab able to contain
2293 the number of objects indicated. The higher the number
2294 of objects the smaller the overhead of tracking slabs
2295 and the less frequently locks need to be acquired.
c1aee215
CL
2296 For more information see Documentation/vm/slub.txt.
2297
2298 slub_min_order= [MM, SLUB]
2299 Determines the mininum page order for slabs. Must be
f0630fff 2300 lower than slub_max_order.
c1aee215
CL
2301 For more information see Documentation/vm/slub.txt.
2302
2303 slub_nomerge [MM, SLUB]
f0630fff 2304 Disable merging of slabs with similar size. May be
c1aee215 2305 necessary if there is some reason to distinguish
f0630fff
CL
2306 allocs to different slabs. Debug options disable
2307 merging on their own.
c1aee215
CL
2308 For more information see Documentation/vm/slub.txt.
2309
1da177e4
LT
2310 smart2= [HW]
2311 Format: <io1>[,<io2>[,...,<io8>]]
2312
cd4f0ef7 2313 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2314 attempt to substitute SMP alternatives once at boot.
2315
d0d4f69b
BH
2316 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2317 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2318 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2319 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2320 smsc-ircc2.ircc_irq= [HW] IRQ line
2321 smsc-ircc2.ircc_dma= [HW] DMA channel
2322 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2323 0: Toshiba Satellite 1800 (GP data pin select)
2324 1: Fast pin select (default)
2325 2: ATC IRMode
2326
1da177e4
LT
2327 snd-ad1816a= [HW,ALSA]
2328
2329 snd-ad1848= [HW,ALSA]
2330
2331 snd-ali5451= [HW,ALSA]
2332
2333 snd-als100= [HW,ALSA]
2334
2335 snd-als4000= [HW,ALSA]
2336
2337 snd-azt2320= [HW,ALSA]
2338
2339 snd-cmi8330= [HW,ALSA]
2340
2341 snd-cmipci= [HW,ALSA]
2342
2343 snd-cs4231= [HW,ALSA]
2344
2345 snd-cs4232= [HW,ALSA]
2346
2347 snd-cs4236= [HW,ALSA]
2348
2349 snd-cs4281= [HW,ALSA]
2350
2351 snd-cs46xx= [HW,ALSA]
2352
2353 snd-dt019x= [HW,ALSA]
2354
2355 snd-dummy= [HW,ALSA]
2356
2357 snd-emu10k1= [HW,ALSA]
2358
2359 snd-ens1370= [HW,ALSA]
2360
2361 snd-ens1371= [HW,ALSA]
2362
2363 snd-es968= [HW,ALSA]
2364
2365 snd-es1688= [HW,ALSA]
2366
2367 snd-es18xx= [HW,ALSA]
2368
2369 snd-es1938= [HW,ALSA]
2370
2371 snd-es1968= [HW,ALSA]
2372
2373 snd-fm801= [HW,ALSA]
2374
2375 snd-gusclassic= [HW,ALSA]
2376
2377 snd-gusextreme= [HW,ALSA]
2378
2379 snd-gusmax= [HW,ALSA]
2380
2381 snd-hdsp= [HW,ALSA]
2382
2383 snd-ice1712= [HW,ALSA]
2384
2385 snd-intel8x0= [HW,ALSA]
2386
2387 snd-interwave= [HW,ALSA]
2388
2389 snd-interwave-stb=
2390 [HW,ALSA]
2391
2392 snd-korg1212= [HW,ALSA]
2393
2394 snd-maestro3= [HW,ALSA]
2395
2396 snd-mpu401= [HW,ALSA]
2397
2398 snd-mtpav= [HW,ALSA]
2399
2400 snd-nm256= [HW,ALSA]
2401
2402 snd-opl3sa2= [HW,ALSA]
2403
2404 snd-opti92x-ad1848=
2405 [HW,ALSA]
2406
2407 snd-opti92x-cs4231=
2408 [HW,ALSA]
2409
2410 snd-opti93x= [HW,ALSA]
2411
2412 snd-pmac= [HW,ALSA]
2413
2414 snd-rme32= [HW,ALSA]
2415
2416 snd-rme96= [HW,ALSA]
2417
2418 snd-rme9652= [HW,ALSA]
2419
2420 snd-sb8= [HW,ALSA]
2421
2422 snd-sb16= [HW,ALSA]
2423
2424 snd-sbawe= [HW,ALSA]
2425
2426 snd-serial= [HW,ALSA]
2427
2428 snd-sgalaxy= [HW,ALSA]
2429
2430 snd-sonicvibes= [HW,ALSA]
2431
2432 snd-sun-amd7930=
2433 [HW,ALSA]
2434
2435 snd-sun-cs4231= [HW,ALSA]
2436
2437 snd-trident= [HW,ALSA]
2438
2439 snd-usb-audio= [HW,ALSA,USB]
2440
2441 snd-via82xx= [HW,ALSA]
2442
2443 snd-virmidi= [HW,ALSA]
2444
2445 snd-wavefront= [HW,ALSA]
2446
2447 snd-ymfpci= [HW,ALSA]
a9913044 2448
9c44bc03
IM
2449 softlockup_panic=
2450 [KNL] Should the soft-lockup detector generate panics.
2451
1da177e4
LT
2452 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2453 See Documentation/sonypi.txt
2454
2455 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2456 See Documentation/serial/specialix.txt.
1da177e4
LT
2457
2458 spia_io_base= [HW,MTD]
2459 spia_fio_base=
2460 spia_pedr=
2461 spia_peddr=
2462
2463 sscape= [HW,OSS]
2464 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2465
1da177e4
LT
2466 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2467 See Documentation/scsi/st.txt.
2468
f38f1d2a
SR
2469 stacktrace [FTRACE]
2470 Enabled the stack tracer on boot up.
2471
1da177e4
LT
2472 sti= [PARISC,HW]
2473 Format: <num>
2474 Set the STI (builtin display/keyboard on the HP-PARISC
2475 machines) console (graphic card) which should be used
2476 as the initial boot-console.
2477 See also comment in drivers/video/console/sticore.c.
2478
2479 sti_font= [HW]
2480 See comment in drivers/video/console/sticore.c.
2481
2482 stifb= [HW]
2483 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2484
cbf11071
TM
2485 sunrpc.min_resvport=
2486 sunrpc.max_resvport=
2487 [NFS,SUNRPC]
2488 SunRPC servers often require that client requests
2489 originate from a privileged port (i.e. a port in the
2490 range 0 < portnr < 1024).
2491 An administrator who wishes to reserve some of these
2492 ports for other uses may adjust the range that the
2493 kernel's sunrpc client considers to be privileged
2494 using these two parameters to set the minimum and
2495 maximum port values.
2496
42a7fc4a
GB
2497 sunrpc.pool_mode=
2498 [NFS]
2499 Control how the NFS server code allocates CPUs to
2500 service thread pools. Depending on how many NICs
2501 you have and where their interrupts are bound, this
2502 option will affect which CPUs will do NFS serving.
2503 Note: this parameter cannot be changed while the
2504 NFS server is running.
2505
2506 auto the server chooses an appropriate mode
2507 automatically using heuristics
2508 global a single global pool contains all CPUs
2509 percpu one pool for each CPU
2510 pernode one pool for each NUMA node (equivalent
2511 to global on non-NUMA machines)
2512
cbf11071
TM
2513 sunrpc.tcp_slot_table_entries=
2514 sunrpc.udp_slot_table_entries=
2515 [NFS,SUNRPC]
2516 Sets the upper limit on the number of simultaneous
2517 RPC calls that can be sent from the client to a
2518 server. Increasing these values may allow you to
2519 improve throughput, but will also increase the
2520 amount of memory reserved for use by the client.
2521
1da177e4 2522 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2523
1da177e4
LT
2524 switches= [HW,M68k]
2525
2526 sym53c416= [HW,SCSI]
2527 See header of drivers/scsi/sym53c416.c.
2528
5d6f647f
IM
2529 sysrq_always_enabled
2530 [KNL]
2531 Ignore sysrq setting - this boot parameter will
2532 neutralize any effect of /proc/sys/kernel/sysrq.
2533 Useful for debugging.
2534
1da177e4
LT
2535 t128= [HW,SCSI]
2536 See header of drivers/scsi/t128.c.
2537
2538 tdfx= [HW,DRM]
2539
77437fd4
DB
2540 test_suspend= [SUSPEND]
2541 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2542 standby suspend) as the system sleep state to briefly
2543 enter during system startup. The system is woken from
2544 this state using a wakeup-capable RTC alarm.
2545
1da177e4
LT
2546 thash_entries= [KNL,NET]
2547 Set number of hash buckets for TCP connection
2548
f8707ec9
LB
2549 thermal.act= [HW,ACPI]
2550 -1: disable all active trip points in all thermal zones
2551 <degrees C>: override all lowest active trip points
2552
c52a7419
LB
2553 thermal.crt= [HW,ACPI]
2554 -1: disable all critical trip points in all thermal zones
22a94d79 2555 <degrees C>: override all critical trip points
c52a7419 2556
f5487145
LB
2557 thermal.nocrt= [HW,ACPI]
2558 Set to disable actions on ACPI thermal zone
2559 critical and hot trip points.
2560
72b33ef8
LB
2561 thermal.off= [HW,ACPI]
2562 1: disable ACPI thermal control
2563
a70cdc52
LB
2564 thermal.psv= [HW,ACPI]
2565 -1: disable all passive trip points
ada9cfdd
RD
2566 <degrees C>: override all passive trip points to this
2567 value
a70cdc52 2568
730ff34d
LB
2569 thermal.tzp= [HW,ACPI]
2570 Specify global default ACPI thermal zone polling rate
2571 <deci-seconds>: poll all this frequency
2572 0: no polling (default)
2573
1da177e4
LT
2574 tmscsim= [HW,SCSI]
2575 See comment before function dc390_setup() in
2576 drivers/scsi/tmscsim.c.
2577
2b1a61f0
HC
2578 topology= [S390]
2579 Format: {off | on}
2580 Specify if the kernel should make use of the cpu
2581 topology informations if the hardware supports these.
2582 The scheduler will make use of these informations and
2583 e.g. base its process migration decisions on it.
2584 Default is off.
2585
1da177e4
LT
2586 tp720= [HW,PS2]
2587
9d612bef
LZ
2588 trace_buf_size=nn[KMG]
2589 [FTRACE] will set tracing buffer size.
631595fb 2590
020e5f85
LZ
2591 trace_event=[event-list]
2592 [FTRACE] Set and start specified trace events in order
2593 to facilitate early boot debugging.
2594 See also Documentation/trace/events.txt
2595
1da177e4 2596 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2597 Format:
2598 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2599
395628ef
AK
2600 tsc= Disable clocksource-must-verify flag for TSC.
2601 Format: <string>
2602 [x86] reliable: mark tsc clocksource as reliable, this
2603 disables clocksource verification at runtime.
2604 Used to enable high-resolution timer mode on older
2605 hardware, and in virtualized environment.
2606
a9913044
RD
2607 turbografx.map[2|3]= [HW,JOY]
2608 TurboGraFX parallel port interface
2609 Format:
2610 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2611 See also Documentation/input/joystick-parport.txt
2612
2613 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2614 See header of drivers/scsi/u14-34f.c.
2615
2616 uart401= [HW,OSS]
2617 Format: <io>,<irq>
2618
2619 uart6850= [HW,OSS]
2620 Format: <io>,<irq>
2621
f86dcc5a
ED
2622 uhash_entries= [KNL,NET]
2623 Set number of hash buckets for UDP/UDP-Lite connections
2624
5f8364b7
AS
2625 uhci-hcd.ignore_oc=
2626 [USB] Ignore overcurrent events (default N).
2627 Some badly-designed motherboards generate lots of
2628 bogus events, for ports that aren't wired to
2629 anything. Set this parameter to avoid log spamming.
2630 Note that genuine overcurrent events won't be
2631 reported either.
2632
e3a61b0a 2633 unknown_nmi_panic
6cececfc 2634 [X86]
e3a61b0a
SA
2635 Set unknown_nmi_panic=1 early on boot.
2636
b5e795f8
AS
2637 usbcore.autosuspend=
2638 [USB] The autosuspend time delay (in seconds) used
2639 for newly-detected USB devices (default 2). This
2640 is the time required before an idle device will be
2641 autosuspended. Devices for which the delay is set
eaafbc3a 2642 to a negative value won't be autosuspended at all.
b5e795f8 2643
fd7c519d
JK
2644 usbcore.usbfs_snoop=
2645 [USB] Set to log all usbfs traffic (default 0 = off).
2646
2647 usbcore.blinkenlights=
2648 [USB] Set to cycle leds on hubs (default 0 = off).
2649
2650 usbcore.old_scheme_first=
2651 [USB] Start with the old device initialization
2652 scheme (default 0 = off).
2653
2654 usbcore.use_both_schemes=
2655 [USB] Try the other device initialization scheme
2656 if the first one fails (default 1 = enabled).
2657
2658 usbcore.initial_descriptor_timeout=
2659 [USB] Specifies timeout for the initial 64-byte
2660 USB_REQ_GET_DESCRIPTOR request in milliseconds
2661 (default 5000 = 5.0 seconds).
2662
1da177e4
LT
2663 usbhid.mousepoll=
2664 [USBHID] The interval which mice are to be polled at.
a9913044 2665
d4f373e5
AS
2666 usb-storage.delay_use=
2667 [UMS] The delay in seconds before a new device is
2668 scanned for Logical Units (default 5).
2669
2670 usb-storage.quirks=
2671 [UMS] A list of quirks entries to supplement or
2672 override the built-in unusual_devs list. List
2673 entries are separated by commas. Each entry has
2674 the form VID:PID:Flags where VID and PID are Vendor
2675 and Product ID values (4-digit hex numbers) and
2676 Flags is a set of characters, each corresponding
2677 to a common usb-storage quirk flag as follows:
c838ea46
AS
2678 a = SANE_SENSE (collect more than 18 bytes
2679 of sense data);
a0bb1081
AS
2680 b = BAD_SENSE (don't collect more than 18
2681 bytes of sense data);
d4f373e5
AS
2682 c = FIX_CAPACITY (decrease the reported
2683 device capacity by one sector);
c838ea46
AS
2684 h = CAPACITY_HEURISTICS (decrease the
2685 reported device capacity by one
2686 sector if the number is odd);
d4f373e5
AS
2687 i = IGNORE_DEVICE (don't bind to this
2688 device);
2689 l = NOT_LOCKABLE (don't try to lock and
2690 unlock ejectable media);
2691 m = MAX_SECTORS_64 (don't transfer more
2692 than 64 sectors = 32 KB at a time);
c838ea46
AS
2693 o = CAPACITY_OK (accept the capacity
2694 reported by the device);
d4f373e5
AS
2695 r = IGNORE_RESIDUE (the device reports
2696 bogus residue values);
2697 s = SINGLE_LUN (the device has only one
2698 Logical Unit);
2699 w = NO_WP_DETECT (don't test whether the
2700 medium is write-protected).
2701 Example: quirks=0419:aaf5:rl,0421:0433:rc
2702
6cececfc 2703 vdso= [X86,SH]
1dbf527c 2704 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2705 vdso=1: enable VDSO (default)
2706 vdso=0: disable VDSO mapping
2707
6cececfc 2708 vdso32= [X86]
af65d648
RM
2709 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2710 vdso32=1: enable 32-bit VDSO (default)
2711 vdso32=0: disable 32-bit VDSO mapping
2712
d080d397
YI
2713 vector= [IA-64,SMP]
2714 vector=percpu: enable percpu vector domain
2715
1da177e4
LT
2716 video= [FB] Frame buffer configuration
2717 See Documentation/fb/modedb.txt.
2718
cd4f0ef7 2719 vga= [BOOT,X86-32] Select a particular video mode
954a8b81 2720 See Documentation/x86/boot.txt and
a9913044 2721 Documentation/svga.txt.
1da177e4
LT
2722 Use vga=ask for menu.
2723 This is actually a boot loader parameter; the value is
2724 passed to the kernel using a special protocol.
2725
a9913044 2726 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2727 size of <nn>. This can be used to increase the
2728 minimum size (128MB on x86). It can also be used to
2729 decrease the size and leave more room for directly
2730 mapped kernel RAM.
2731
585c3047
PO
2732 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2733 Format: <command>
1da177e4 2734
585c3047
PO
2735 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2736 Format: <command>
2737
2738 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2739 Format: <command>
a9913044 2740
9ea9a886
CL
2741 vt.cur_default= [VT] Default cursor shape.
2742 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2743 the parameters of the <Esc>[?A;B;Cc escape sequence;
2744 see VGA-softcursor.txt. Default: 2 = underline.
2745
0cb55ad2
RD
2746 vt.default_blu= [VT]
2747 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2748 Change the default blue palette of the console.
2749 This is a 16-member array composed of values
2750 ranging from 0-255.
2751
2752 vt.default_grn= [VT]
2753 Format: <green0>,<green1>,<green2>,...,<green15>
2754 Change the default green palette of the console.
2755 This is a 16-member array composed of values
2756 ranging from 0-255.
2757
2758 vt.default_red= [VT]
2759 Format: <red0>,<red1>,<red2>,...,<red15>
2760 Change the default red palette of the console.
2761 This is a 16-member array composed of values
2762 ranging from 0-255.
2763
2764 vt.default_utf8=
2765 [VT]
2766 Format=<0|1>
2767 Set system-wide default UTF-8 mode for all tty's.
2768 Default is 1, i.e. UTF-8 mode is enabled for all
2769 newly opened terminals.
2770
f6c06b68
MG
2771 vt.global_cursor_default=
2772 [VT]
2773 Format=<-1|0|1>
2774 Set system-wide default for whether a cursor
2775 is shown on new VTs. Default is -1,
2776 i.e. cursors will be created by default unless
2777 overridden by individual drivers. 0 will hide
2778 cursors, 1 will display them.
2779
1da177e4
LT
2780 waveartist= [HW,OSS]
2781 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2782
1da177e4
LT
2783 wd33c93= [HW,SCSI]
2784 See header of drivers/scsi/wd33c93.c.
2785
2786 wd7000= [HW,SCSI]
2787 See header of drivers/scsi/wd7000.c.
2788
2789 wdt= [WDT] Watchdog
8dfe9c21 2790 See Documentation/watchdog/wdt.txt.
1da177e4 2791
0cb55ad2
RD
2792 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2793 default x2apic cluster mode on platforms
2794 supporting x2apic.
2795
1da177e4
LT
2796 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2797 xd_geo= See header of drivers/block/xd.c.
2798
2799 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2800 Format:
2801 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2802
a9913044 2803______________________________________________________________________
1da177e4
LT
2804
2805TODO:
2806
2807 Add documentation for ALSA options.
2808 Add more DRM drivers.