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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.
b0f83b28 57 IPV6 IPv6 support is enabled.
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58 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
fef07aae 61 KVM Kernel Virtual Machine support is enabled.
11ef697b 62 LIBATA Libata driver is enabled
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63 LP Printer support is enabled.
64 LOOP Loopback device support is enabled.
65 M68k M68k architecture is enabled.
66 These options have more detailed description inside of
67 Documentation/m68k/kernel-options.txt.
68 MCA MCA bus support is enabled.
69 MDA MDA console support is enabled.
70 MOUSE Appropriate mouse support is enabled.
309e57df 71 MSI Message Signaled Interrupts (PCI).
c8facbb6 72 MTD MTD (Memory Technology Device) support is enabled.
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73 NET Appropriate network support is enabled.
74 NUMA NUMA support is enabled.
734efb46 75 GENERIC_TIME The generic timeofday code is enabled.
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76 NFS Appropriate NFS support is enabled.
77 OSS OSS sound support is enabled.
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78 PV_OPS A paravirtualized kernel is enabled.
79 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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80 PARISC The PA-RISC architecture is enabled.
81 PCI PCI bus support is enabled.
7f785763 82 PCIE PCI Express support is enabled.
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83 PCMCIA The PCMCIA subsystem is enabled.
84 PNP Plug & Play support is enabled.
85 PPC PowerPC architecture is enabled.
86 PPT Parallel port support is enabled.
87 PS2 Appropriate PS/2 support is enabled.
88 RAM RAM disk support is enabled.
89 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
92 Documentation/scsi/.
20510f2f 93 SECURITY Different security models are enabled.
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94 SELINUX SELinux support is enabled.
95 SERIAL Serial support is enabled.
e523d93c 96 SH SuperH architecture is enabled.
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97 SMP The kernel is an SMP kernel.
98 SPARC Sparc architecture is enabled.
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99 SWSUSP Software suspend (hibernation) is enabled.
100 SUSPEND System suspend states are enabled.
f38f1d2a 101 FTRACE Function tracing enabled.
1da177e4 102 TS Appropriate touchscreen support is enabled.
d4f373e5 103 UMS USB Mass Storage support is enabled.
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104 USB USB support is enabled.
105 USBHID USB Human Interface Device support is enabled.
106 V4L Video For Linux support is enabled.
107 VGA The VGA console has been enabled.
108 VT Virtual terminal support is enabled.
109 WDT Watchdog support is enabled.
110 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 111 X86-32 X86-32, aka i386 architecture is enabled.
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112 X86-64 X86-64 architecture is enabled.
113 More X86-64 boot options can be found in
71cced6e 114 Documentation/x86/x86_64/boot-options.txt .
c0115606 115 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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116
117In addition, the following text indicates that the option:
118
119 BUGS= Relates to possible processor bugs on the said processor.
120 KNL Is a kernel start-up parameter.
121 BOOT Is a boot loader parameter.
122
123Parameters denoted with BOOT are actually interpreted by the boot
124loader, and have no meaning to the kernel directly.
125Do not modify the syntax of boot loader parameters without extreme
954a8b81 126need or coordination with <Documentation/x86/boot.txt>.
1da177e4 127
5558870b 128There are also arch-specific kernel-parameters not documented here.
71cced6e 129See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 130
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131Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
132a trailing = on the name of any parameter states that that parameter will
133be entered as an environment variable, whereas its absence indicates that
134it will appear as a kernel argument readable via /proc/cmdline by programs
135running once the system is up.
136
9c4751fd 137The number of kernel parameters is not limited, but the length of the
138complete command line (parameters including spaces etc.) is limited to
139a fixed number of characters. This limit depends on the architecture
140and is between 256 and 4096 characters. It is defined in the file
141./include/asm/setup.h as COMMAND_LINE_SIZE.
142
143
6cececfc 144 acpi= [HW,ACPI,X86]
03d926f8 145 Advanced Configuration and Power Interface
af23f573 146 Format: { force | off | ht | strict | noirq | rsdt }
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147 force -- enable ACPI if default was off
148 off -- disable ACPI if default was on
149 noirq -- do not use ACPI for IRQ routing
150 ht -- run only enough ACPI to enable Hyper Threading
a9913044 151 strict -- Be less tolerant of platforms that are not
1da177e4 152 strictly ACPI specification compliant.
237889bf 153 rsdt -- prefer RSDT over (default) XSDT
1da177e4 154
53471121 155 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 156
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157 acpi_apic_instance= [ACPI, IOAPIC]
158 Format: <int>
159 2: use 2nd APIC table, if available
160 1,0: use 1st APIC table
4e381a4f 161 default: 0
a1fdcc0d 162
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163 acpi_backlight= [HW,ACPI]
164 acpi_backlight=vendor
165 acpi_backlight=video
166 If set to vendor, prefer vendor specific driver
167 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
168 of the ACPI video.ko driver.
169
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170 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
171 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 172 Format: <int>
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173 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
174 debug output. Bits in debug_layer correspond to a
175 _COMPONENT in an ACPI source file, e.g.,
176 #define _COMPONENT ACPI_PCI_COMPONENT
177 Bits in debug_level correspond to a level in
178 ACPI_DEBUG_PRINT statements, e.g.,
179 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
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180 The debug_level mask defaults to "info". See
181 Documentation/acpi/debug.txt for more information about
182 debug layers and levels.
a0d84a92 183
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184 Enable processor driver info messages:
185 acpi.debug_layer=0x20000000
186 Enable PCI/PCI interrupt routing info messages:
187 acpi.debug_layer=0x400000
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188 Enable AML "Debug" output, i.e., stores to the Debug
189 object while interpreting AML:
190 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
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191 Enable all messages related to ACPI hardware:
192 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
193
194 Some values produce so much output that the system is
195 unusable. The "log_buf_len" parameter may be useful
196 if you need to capture more output.
f989106c 197
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198 acpi_display_output= [HW,ACPI]
199 acpi_display_output=vendor
200 acpi_display_output=video
201 See above.
202
203 acpi_irq_balance [HW,ACPI]
204 ACPI will balance active IRQs
205 default in APIC mode
206
207 acpi_irq_nobalance [HW,ACPI]
208 ACPI will not move active IRQs (default)
209 default in PIC mode
210
211 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
212 Format: <irq>,<irq>...
213
214 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
215 use by PCI
216 Format: <irq>,<irq>...
217
218 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
219
220 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
221 Format: To spoof as Windows 98: ="Microsoft Windows"
222
223 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
224 acpi_osi="string1" # add string1 -- only one string
225 acpi_osi="!string2" # remove built-in string2
226 acpi_osi= # disable all strings
227
6cececfc 228 acpi_pm_good [X86]
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229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
232
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233 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
234 Format: { level | edge | high | low }
235
236 acpi_serialize [HW,ACPI] force serialization of AML methods
237
238 acpi_skip_timer_override [HW,ACPI]
239 Recognize and ignore IRQ0/pin2 Interrupt Override.
240 For broken nForce2 BIOS resulting in XT-PIC timer.
241
242 acpi_sleep= [HW,ACPI] Sleep options
243 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
d7f0eea9 244 old_ordering, s4_nonvs, sci_force_enable }
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245 See Documentation/power/video.txt for information on
246 s3_bios and s3_mode.
247 s3_beep is for debugging; it makes the PC's speaker beep
248 as soon as the kernel's real-mode entry point is called.
249 s4_nohwsig prevents ACPI hardware signature from being
250 used during resume from hibernation.
251 old_ordering causes the ACPI 1.0 ordering of the _PTS
252 control method, with respect to putting devices into
253 low power states, to be enforced (the ACPI 2.0 ordering
254 of _PTS is used by default).
255 s4_nonvs prevents the kernel from saving/restoring the
256 ACPI NVS memory during hibernation.
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257 sci_force_enable causes the kernel to set SCI_EN directly
258 on resume from S1/S3 (which is against the ACPI spec,
259 but some broken systems don't work without it).
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260
261 acpi_use_timer_override [HW,ACPI]
262 Use timer override. For some broken Nvidia NF5 boards
263 that require a timer override, but don't have HPET
264
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265 acpi_enforce_resources= [ACPI]
266 { strict | lax | no }
267 Check for resource conflicts between native drivers
268 and ACPI OperationRegions (SystemIO and SystemMemory
269 only). IO ports and memory declared in ACPI might be
270 used by the ACPI subsystem in arbitrary AML code and
271 can interfere with legacy drivers.
272 strict (default): access to resources claimed by ACPI
273 is denied; legacy drivers trying to access reserved
274 resources will fail to bind to device using them.
275 lax: access to resources claimed by ACPI is allowed;
276 legacy drivers trying to access reserved resources
277 will bind successfully but a warning message is logged.
278 no: ACPI OperationRegions are not marked as reserved,
279 no further checks are performed.
280
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281 ad1848= [HW,OSS]
282 Format: <io>,<irq>,<dma>,<dma2>,<type>
283
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284 add_efi_memmap [EFI; X86] Include EFI memory map in
285 kernel's map of available physical RAM.
286
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287 advansys= [HW,SCSI]
288 See header of drivers/scsi/advansys.c.
289
290 advwdt= [HW,WDT] Advantech WDT
291 Format: <iostart>,<iostop>
292
293 aedsp16= [HW,OSS] Audio Excel DSP 16
294 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
295 See also header of sound/oss/aedsp16.c.
a9913044 296
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297 agp= [AGP]
298 { off | try_unsupported }
299 off: disable AGP support
300 try_unsupported: try to drive unsupported chipsets
301 (may crash computer or cause data corruption)
302
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303 aha152x= [HW,SCSI]
304 See Documentation/scsi/aha152x.txt.
305
306 aha1542= [HW,SCSI]
307 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
308
309 aic7xxx= [HW,SCSI]
310 See Documentation/scsi/aic7xxx.txt.
311
312 aic79xx= [HW,SCSI]
313 See Documentation/scsi/aic79xx.txt.
314
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315 alignment= [KNL,ARM]
316 Allow the default userspace alignment fault handler
317 behaviour to be specified. Bit 0 enables warnings,
318 bit 1 enables fixups, and bit 2 sends a segfault.
319
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320 amd_iommu= [HW,X86-84]
321 Pass parameters to the AMD IOMMU driver in the system.
322 Possible values are:
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323 isolate - enable device isolation (each device, as far
324 as possible, will get its own protection
3ce1f93c 325 domain) [default]
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326 share - put every device behind one IOMMU into the
327 same protection domain
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328 fullflush - enable flushing of IO/TLB entries when
329 they are unmapped. Otherwise they are
330 flushed before they will be reused, which
331 is a lot of faster
332
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333 amijoy.map= [HW,JOY] Amiga joystick support
334 Map of devices attached to JOY0DAT and JOY1DAT
335 Format: <a>,<b>
336 See also Documentation/kernel/input/joystick.txt
337
338 analog.map= [HW,JOY] Analog joystick and gamepad support
339 Specifies type or capabilities of an analog joystick
340 connected to one of 16 gameports
341 Format: <type1>,<type2>,..<type16>
342
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343 apc= [HW,SPARC]
344 Power management functions (SPARCstation-4/5 + deriv.)
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345 Format: noidle
346 Disable APC CPU standby support. SPARCstation-Fox does
347 not play well with APC CPU idle - disable it if you have
348 APC and your system crashes randomly.
349
ca1eda2d 350 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
c8facbb6 351 Change the output verbosity whilst booting
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352 Format: { quiet (default) | verbose | debug }
353 Change the amount of debugging information output
354 when initialising the APIC and IO-APIC components.
a9913044 355
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356 autoconf= [IPV6]
357 See Documentation/networking/ipv6.txt.
358
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359 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
360 Limit apic dumping. The parameter defines the maximal
361 number of local apics being dumped. Also it is possible
362 to set it to "all" by meaning -- no limit here.
363 Format: { 1 (default) | 2 | ... | all }.
364 The parameter valid if only apic=debug or
365 apic=verbose is specified.
366 Example: apic=debug show_lapic=all
367
1da177e4 368 apm= [APM] Advanced Power Management
71f77055 369 See header of arch/x86/kernel/apm_32.c.
1da177e4 370
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371 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
372 Format: <io>,<irq>,<nodeID>
373
374 ataflop= [HW,M68k]
375
376 atarimouse= [HW,MOUSE] Atari Mouse
377
378 atascsi= [HW,SCSI] Atari SCSI
379
380 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
381 EzKey and similar keyboards
382
383 atkbd.reset= [HW] Reset keyboard during initialization
384
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385 atkbd.set= [HW] Select keyboard code set
386 Format: <int> (2 = AT (default), 3 = PS/2)
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387
388 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
389 keyboards
390
391 atkbd.softraw= [HW] Choose between synthetic and real raw mode
392 Format: <bool> (0 = real, 1 = synthetic (default))
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393
394 atkbd.softrepeat= [HW]
395 Use software keyboard repeat
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396
397 autotest [IA64]
398
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399 baycom_epp= [HW,AX25]
400 Format: <io>,<mode>
a9913044 401
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402 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
403 Format: <io>,<mode>
404 See header of drivers/net/hamradio/baycom_par.c.
405
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406 baycom_ser_fdx= [HW,AX25]
407 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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408 Format: <io>,<irq>,<mode>[,<baud>]
409 See header of drivers/net/hamradio/baycom_ser_fdx.c.
410
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411 baycom_ser_hdx= [HW,AX25]
412 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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413 Format: <io>,<irq>,<mode>
414 See header of drivers/net/hamradio/baycom_ser_hdx.c.
415
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416 boot_delay= Milliseconds to delay each printk during boot.
417 Values larger than 10 seconds (10000) are changed to
418 no delay (0).
419 Format: integer
420
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421 bootmem_debug [KNL] Enable bootmem allocator debug messages.
422
1da177e4 423 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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424 bttv.radio= Most important insmod options are available as
425 kernel args too.
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426 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
427 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
428
429 BusLogic= [HW,SCSI]
430 See drivers/scsi/BusLogic.c, comment before function
431 BusLogic_ParseDriverOptions().
432
433 c101= [NET] Moxa C101 synchronous serial card
434
cd4f0ef7 435 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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436 Sometimes CPU hardware bugs make them report the cache
437 size incorrectly. The kernel will attempt work arounds
438 to fix known problems, but for some CPUs it is not
439 possible to determine what the correct size should be.
440 This option provides an override for these situations.
441
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442 capability.disable=
443 [SECURITY] Disable capabilities. This would normally
444 be used only if an alternative security model is to be
445 configured. Potentially dangerous and should only be
446 used if you are entirely sure of the consequences.
447
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448 ccw_timeout_log [S390]
449 See Documentation/s390/CommonIO for details.
1da177e4 450
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451 cgroup_disable= [KNL] Disable a particular controller
452 Format: {name of the controller(s) to disable}
453 {Currently supported controllers - "memory"}
454
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455 checkreqprot [SELINUX] Set initial checkreqprot flag value.
456 Format: { "0" | "1" }
457 See security/selinux/Kconfig help text.
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458 0 -- check protection applied by kernel (includes
459 any implied execute protection).
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460 1 -- check protection requested by application.
461 Default value is set via a kernel config option.
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462 Value can be changed at runtime via
463 /selinux/checkreqprot.
464
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465 cio_ignore= [S390]
466 See Documentation/s390/CommonIO for details.
467
cd4f0ef7 468 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 469 [Deprecated]
3f6dee9b 470 Forces specified clocksource (if available) to be used
734efb46 471 when calculating gettimeofday(). If specified
3f6dee9b 472 clocksource is not available, it defaults to PIT.
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473 Format: { pit | tsc | cyclone | pmtmr }
474
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475 clocksource= [GENERIC_TIME] Override the default clocksource
476 Format: <string>
477 Override the default clocksource and use the clocksource
478 with the name specified.
479 Some clocksource names to choose from, depending on
480 the platform:
481 [all] jiffies (this is the base, fallback clocksource)
482 [ACPI] acpi_pm
483 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
484 pxa_timer,timer3,32k_counter,timer0_1
485 [AVR32] avr32
cd4f0ef7 486 [X86-32] pit,hpet,tsc,vmi-timer;
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487 scx200_hrt on Geode; cyclone on IBM x440
488 [MIPS] MIPS
489 [PARISC] cr16
490 [S390] tod
491 [SH] SuperH
492 [SPARC64] tick
493 [X86-64] hpet,tsc
494
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495 clearcpuid=BITNUM [X86]
496 Disable CPUID feature X for the kernel. See
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497 arch/x86/include/asm/cpufeature.h for the valid bit
498 numbers. Note the Linux specific bits are not necessarily
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499 stable over kernel options, but the vendor specific
500 ones should be.
501 Also note that user programs calling CPUID directly
502 or using the feature without checking anything
503 will still see it. This just prevents it from
504 being used by the kernel or shown in /proc/cpuinfo.
505 Also note the kernel might malfunction if you disable
506 some critical bits.
507
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508 cmo_free_hint= [PPC] Format: { yes | no }
509 Specify whether pages are marked as being inactive
510 when they are freed. This is used in CMO environments
511 to determine OS memory pressure for page stealing by
512 a hypervisor.
513 Default: yes
514
6cececfc 515 code_bytes [X86] How many bytes of object code to print
a25bd949 516 in an oops report.
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517 Range: 0 - 8192
518 Default: 64
519
1da177e4 520 com20020= [HW,NET] ARCnet - COM20020 chipset
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521 Format:
522 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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523
524 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
525 Format: <io>[,<irq>]
526
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527 com90xx= [HW,NET]
528 ARCnet - COM90xx chipset (memory-mapped buffers)
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529 Format: <io>[,<irq>[,<memstart>]]
530
531 condev= [HW,S390] console device
532 conmode=
a9913044 533
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534 console= [KNL] Output console device and options.
535
536 tty<n> Use the virtual console device <n>.
537
538 ttyS<n>[,options]
f1a1c2dc 539 ttyUSB0[,options]
1da177e4 540 Use the specified serial port. The options are of
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RD
541 the form "bbbbpnf", where "bbbb" is the baud rate,
542 "p" is parity ("n", "o", or "e"), "n" is number of
543 bits, and "f" is flow control ("r" for RTS or
544 omit it). Default is "9600n8".
545
546 See Documentation/serial-console.txt for more
547 information. See
548 Documentation/networking/netconsole.txt for an
549 alternative.
1da177e4 550
18a8bd94
YL
551 uart[8250],io,<addr>[,options]
552 uart[8250],mmio,<addr>[,options]
1da177e4
LT
553 Start an early, polled-mode console on the 8250/16550
554 UART at the specified I/O port or MMIO address,
555 switching to the matching ttyS device later. The
556 options are the same as for ttyS, above.
557
f7511d5f
ST
558 If the device connected to the port is not a TTY but a braille
559 device, prepend "brl," before the device type, for instance
560 console=brl,ttyS0
561 For now, only VisioBraille is supported.
562
f324edc8
DM
563 consoleblank= [KNL] The console blank (screen saver) timeout in
564 seconds. Defaults to 10*60 = 10mins. A value of 0
565 disables the blank timer.
566
4cb0e11b
HK
567 coredump_filter=
568 [KNL] Change the default value for
569 /proc/<pid>/coredump_filter.
570 See also Documentation/filesystems/proc.txt.
571
1da177e4 572 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
573 Format:
574 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 575
dc009d92
EB
576 crashkernel=nn[KMG]@ss[KMG]
577 [KNL] Reserve a chunk of physical memory to
578 hold a kernel to switch to with kexec on panic.
579
fb391599
BW
580 crashkernel=range1:size1[,range2:size2,...][@offset]
581 [KNL] Same as above, but depends on the memory
582 in the running system. The syntax of range is
583 start-[end] where start and end are both
584 a memory unit (amount[KMG]). See also
585 Documentation/kdump/kdump.txt for a example.
586
1da177e4
LT
587 cs89x0_dma= [HW,NET]
588 Format: <dma>
589
590 cs89x0_media= [HW,NET]
591 Format: { rj45 | aui | bnc }
a9913044 592
a9913044 593 dasd= [HW,NET]
1da177e4
LT
594 See header of drivers/s390/block/dasd_devmap.c.
595
596 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
597 (one device per port)
598 Format: <port#>,<type>
599 See also Documentation/input/joystick-parport.txt
600
601 debug [KNL] Enable kernel debugging (events log level).
602
cae2ed9a
IM
603 debug_locks_verbose=
604 [KNL] verbose self-tests
605 Format=<0|1>
606 Print debugging info while doing the locking API
607 self-tests.
608 We default to 0 (no extra messages), setting it to
609 1 will print _a lot_ more information - normally
610 only useful to kernel developers.
611
3ac7fe5a
TG
612 debug_objects [KNL] Enable object debugging
613
3e8ebb5c
KM
614 no_debug_objects
615 [KNL] Disable object debugging
616
d3af01f1
TG
617 debugpat [X86] Enable PAT debugging
618
2d27a966 619 decnet.addr= [HW,NET]
1da177e4
LT
620 Format: <area>[,<node>]
621 See also Documentation/networking/decnet.txt.
622
0cb55ad2
RD
623 default_hugepagesz=
624 [same as hugepagesz=] The size of the default
625 HugeTLB page size. This is the size represented by
626 the legacy /proc/ hugepages APIs, used for SHM, and
627 default size when mounting hugetlbfs filesystems.
628 Defaults to the default architecture's huge page size
629 if not specified.
55ff9780 630
1da177e4
LT
631 dhash_entries= [KNL]
632 Set number of hash buckets for dentry cache.
a9913044 633
1da177e4
LT
634 digi= [HW,SERIAL]
635 IO parameters + enable/disable command.
636
637 digiepca= [HW,SERIAL]
638 See drivers/char/README.epca and
31c00fc1 639 Documentation/serial/digiepca.txt.
1da177e4 640
b0f83b28
BH
641 disable= [IPV6]
642 See Documentation/networking/ipv6.txt.
643
644 disable_ipv6= [IPV6]
645 See Documentation/networking/ipv6.txt.
646
95ffa243 647 disable_mtrr_cleanup [X86]
95ffa243
YL
648 The kernel tries to adjust MTRR layout from continuous
649 to discrete, to make X server driver able to add WB
0cb55ad2 650 entry later. This parameter disables that.
95ffa243 651
093af8d7 652 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
653 By default the kernel will trim any uncacheable
654 memory out of your available memory pool based on
655 MTRR settings. This parameter disables that behavior,
656 possibly causing your machine to run very slowly.
657
6cececfc 658 disable_timer_pin_1 [X86]
0cb55ad2
RD
659 Disable PIN 1 of APIC timer
660 Can be useful to work around chipset bugs.
661
1da177e4
LT
662 dmasound= [HW,OSS] Sound subsystem buffers
663
0cb55ad2
RD
664 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
665 this option disables the debugging code at boot.
666
667 dma_debug_entries=<number>
668 This option allows to tune the number of preallocated
669 entries for DMA-API debugging code. One entry is
670 required per DMA-API allocation. Use this if the
671 DMA-API debugging code disables itself because the
672 architectural default is too low.
673
1745de5e
JR
674 dma_debug_driver=<driver_name>
675 With this option the DMA-API debugging driver
676 filter feature can be enabled at boot time. Just
677 pass the driver to filter for as the parameter.
678 The filter can be disabled or changed to another
679 driver later using sysfs.
680
1da177e4
LT
681 dscc4.setup= [NET]
682
683 dtc3181e= [HW,SCSI]
684
0cb55ad2
RD
685 dynamic_printk Enables pr_debug()/dev_dbg() calls if
686 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
687 These can also be switched on/off via
688 <debugfs>/dynamic_printk/modules
689
690 earlycon= [KNL] Output early console device and options.
691 uart[8250],io,<addr>[,options]
692 uart[8250],mmio,<addr>[,options]
693 Start an early, polled-mode console on the 8250/16550
694 UART at the specified I/O port or MMIO address.
695 The options are the same as for ttyS, above.
696
6cececfc 697 earlyprintk= [X86,SH,BLACKFIN]
1da177e4
LT
698 earlyprintk=vga
699 earlyprintk=serial[,ttySn[,baudrate]]
ea3acb19 700 earlyprintk=ttySn[,baudrate]
9780bc41 701 earlyprintk=dbgp[debugController#]
1da177e4 702
a9913044 703 Append ",keep" to not disable it when the real console
1da177e4
LT
704 takes over.
705
5c05917e 706 Only vga or serial or usb debug port at a time.
1da177e4
LT
707
708 Currently only ttyS0 and ttyS1 are supported.
709
710 Interaction with the standard serial driver is not
711 very good.
712
713 The VGA output is eventually overwritten by the real
714 console.
715
716 eata= [HW,SCSI]
717
1da177e4 718 edd= [EDD]
8c4dd606 719 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 720
1da177e4
LT
721 eisa_irq_edge= [PARISC,HW]
722 See header of drivers/parisc/eisa.c.
723
cd4f0ef7 724 elanfreq= [X86-32]
1da177e4 725 See comment before function elanfreq_setup() in
71f77055 726 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
727
728 elevator= [IOSCHED]
16ab3adf 729 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
730 See Documentation/block/as-iosched.txt and
731 Documentation/block/deadline-iosched.txt for details.
732
6cececfc 733 elfcorehdr= [IA64,PPC,SH,X86]
a9913044 734 Specifies physical address of start of kernel core
aac04b32
VG
735 image elf header. Generally kexec loader will
736 pass this option to capture kernel.
737 See Documentation/kdump/kdump.txt for details.
1da177e4 738
0cb55ad2
RD
739 enable_mtrr_cleanup [X86]
740 The kernel tries to adjust MTRR layout from continuous
741 to discrete, to make X server driver able to add WB
742 entry later. This parameter enables that.
743
ca1eda2d 744 enable_timer_pin_1 [X86]
0cb55ad2
RD
745 Enable PIN 1 of APIC timer
746 Can be useful to work around chipset bugs
747 (in particular on some ATI chipsets).
748 The kernel tries to set a reasonable default.
749
1da177e4
LT
750 enforcing [SELINUX] Set initial enforcing status.
751 Format: {"0" | "1"}
752 See security/selinux/Kconfig help text.
753 0 -- permissive (log only, no denials).
754 1 -- enforcing (deny and log).
755 Default value is 0.
756 Value can be changed at runtime via /selinux/enforce.
757
1da177e4
LT
758 ether= [HW,NET] Ethernet cards parameters
759 This option is obsoleted by the "netdev=" option, which
760 has equivalent usage. See its documentation for details.
761
762 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
763 Format: <io>[,<irq>]
764
de1ba09b
AM
765 failslab=
766 fail_page_alloc=
767 fail_make_request=[KNL]
768 General fault injection mechanism.
769 Format: <interval>,<probability>,<space>,<times>
770 See also /Documentation/fault-injection/.
771
1da177e4
LT
772 fd_mcs= [HW,SCSI]
773 See header of drivers/scsi/fd_mcs.c.
774
775 fdomain= [HW,SCSI]
776 See header of drivers/scsi/fdomain.c.
777
778 floppy= [HW]
31c00fc1 779 See Documentation/blockdev/floppy.txt.
1da177e4 780
f13ae30e
AC
781 force_pal_cache_flush
782 [IA-64] Avoid check_sal_cache_flush which may hang on
783 buggy SAL_CACHE_FLUSH implementations. Using this
784 parameter will force ia64_sal_cache_flush to call
785 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
786
d9e54076 787 ftrace=[tracer]
2af15d6a 788 [FTRACE] will set and start the specified tracer
d9e54076
PZ
789 as early as possible in order to facilitate early
790 boot debugging.
791
792 ftrace_dump_on_oops
2af15d6a
SR
793 [FTRACE] will dump the trace buffers on oops.
794
795 ftrace_filter=[function-list]
796 [FTRACE] Limit the functions traced by the function
797 tracer at boot up. function-list is a comma separated
798 list of functions. This list can be changed at run
799 time by the set_ftrace_filter file in the debugfs
800 tracing directory.
801
802 ftrace_notrace=[function-list]
803 [FTRACE] Do not trace the functions specified in
804 function-list. This list can be changed at run time
805 by the set_ftrace_notrace file in the debugfs
806 tracing directory.
d9e54076 807
369bc18f
SA
808 ftrace_graph_filter=[function-list]
809 [FTRACE] Limit the top level callers functions traced
810 by the function graph tracer at boot up.
811 function-list is a comma separated list of functions
812 that can be changed at run time by the
813 set_graph_function file in the debugfs tracing directory.
814
1da177e4
LT
815 gamecon.map[2|3]=
816 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
817 support via parallel port (up to 5 devices per port)
818 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
819 See also Documentation/input/joystick-parport.txt
820
821 gamma= [HW,DRM]
822
aaf23042
YL
823 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
824 Format: off | on
825 default: on
826
2521f2c2
PO
827 gcov_persist= [GCOV] When non-zero (default), profiling data for
828 kernel modules is saved and remains accessible via
829 debugfs, even when the module is unloaded/reloaded.
830 When zero, profiling data is discarded and associated
831 debugfs files are removed at module unload time.
832
1da177e4
LT
833 gdth= [HW,SCSI]
834 See header of drivers/scsi/gdth.c.
835
836 gpt [EFI] Forces disk with valid GPT signature but
837 invalid Protective MBR to be treated as GPT.
838
1da177e4
LT
839 gvp11= [HW,SCSI]
840
841 hashdist= [KNL,NUMA] Large hashes allocated during boot
842 are distributed across NUMA nodes. Defaults on
429aa0fc 843 for 64bit NUMA, off otherwise.
a9913044 844 Format: 0 | 1 (for off | on)
1da177e4
LT
845
846 hcl= [IA-64] SGI's Hardware Graph compatibility layer
847
848 hd= [EIDE] (E)IDE hard drive subsystem geometry
849 Format: <cyl>,<head>,<sect>
850
1da177e4
LT
851 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
852 size of <nn>. This works even on boxes that have no
853 highmem otherwise. This also works to reduce highmem
854 size on bigger boxes.
855
54cdfdb4
TG
856 highres= [KNL] Enable/disable high resolution timer mode.
857 Valid parameters: "on", "off"
858 Default: "on"
859
1da177e4
LT
860 hisax= [HW,ISDN]
861 See Documentation/isdn/README.HiSax.
862
0cb55ad2
RD
863 hlt [BUGS=ARM,SH]
864
865 hpet= [X86-32,HPET] option to control HPET usage
866 Format: { enable (default) | disable | force |
867 verbose }
868 disable: disable HPET and use PIT instead
869 force: allow force enabled of undocumented chips (ICH4,
870 VIA, nVidia)
871 verbose: show contents of HPET registers during setup
872
b4718e62
AK
873 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
874 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
875 On x86-64 and powerpc, this option can be specified
876 multiple times interleaved with hugepages= to reserve
877 huge pages of different sizes. Valid pages sizes on
878 x86-64 are 2M (when the CPU supports "pse") and 1G
879 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
880 Note that 1GB pages can only be allocated at boot time
881 using hugepages= and not freed afterwards.
6902aa84 882
555d61d6
HB
883 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
884 terminal devices. Valid values: 0..8
431429ff
HB
885 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
886 If specified, z/VM IUCV HVC accepts connections
887 from listed z/VM user IDs only.
cef7125d 888
3a853fb9 889 i2c_bus= [HW] Override the default board specific I2C bus speed
7954763b
JN
890 or register an additional I2C bus that is not
891 registered from board initialization code.
3a853fb9
JN
892 Format:
893 <bus_id>,<clkrate>
894
36d95739 895 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 896 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
897 i8042.dumbkbd [HW] Pretend that controller can only read data from
898 keyboard and cannot control its state
1da177e4
LT
899 (Don't attempt to blink the leds)
900 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 901 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
902 i8042.noloop [HW] Disable the AUX Loopback command while probing
903 for the AUX port
1da177e4
LT
904 i8042.nomux [HW] Don't check presence of an active multiplexing
905 controller
906 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
907 controllers
908 i8042.panicblink=
909 [HW] Frequency with which keyboard LEDs should blink
910 when kernel panics (default is 0.5 sec)
911 i8042.reset [HW] Reset the controller during init and cleanup
912 i8042.unlock [HW] Unlock (ignore) the keylock
913
914 i810= [HW,DRM]
915
e70c9d5e
DT
916 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
917 indicates that the driver is running on unsupported
918 hardware.
1da177e4
LT
919 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
920 does not match list of supported models.
921 i8k.power_status
922 [HW] Report power status in /proc/i8k
923 (disabled by default)
924 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
925 capability is set.
926
927 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
928 See Documentation/mca.txt.
929
930 icn= [HW,ISDN]
931 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
932
0af80c04
DF
933 ide-core.nodma= [HW] (E)IDE subsystem
934 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
075affcb
BZ
935 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
936 .cdrom .chs .ignore_cable are additional options
1c10e938 937 See Documentation/ide/ide.txt.
1da177e4 938
0cb55ad2
RD
939 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
940 Claim all unknown PCI IDE storage controllers.
941
f039b754 942 idle= [X86]
ada9cfdd
RD
943 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
944 Poll forces a polling idle loop that can slightly
945 improve the performance of waking up a idle CPU, but
946 will use a lot of power and make the system run hot.
947 Not recommended.
948 idle=mwait: On systems which support MONITOR/MWAIT but
949 the kernel chose to not use it because it doesn't save
950 as much power as a normal idle loop, use the
951 MONITOR/MWAIT idle loop anyways. Performance should be
952 the same as idle=poll.
953 idle=halt: Halt is forced to be used for CPU idle.
c1e3b377 954 In such case C2/C3 won't be used again.
ada9cfdd 955 idle=nomwait: Disable mwait for CPU C-states
a9913044 956
79290822
IM
957 ignore_loglevel [KNL]
958 Ignore loglevel setting - this will print /all/
959 kernel messages to the console. Useful for debugging.
960
1da177e4
LT
961 ihash_entries= [KNL]
962 Set number of hash buckets for inode cache.
963
3323eec9
MZ
964 ima_audit= [IMA]
965 Format: { "0" | "1" }
966 0 -- integrity auditing messages. (Default)
967 1 -- enable informational integrity auditing messages.
968
969 ima_hash= [IMA]
a9ed83a5 970 Format: { "sha1" | "md5" }
3323eec9
MZ
971 default: "sha1"
972
5789ba3b
EP
973 ima_tcb [IMA]
974 Load a policy which meets the needs of the Trusted
975 Computing Base. This means IMA will measure all
976 programs exec'd, files mmap'd for exec, and all files
977 opened for read by uid=0.
978
1da177e4
LT
979 in2000= [HW,SCSI]
980 See header of drivers/scsi/in2000.c.
981
982 init= [KNL]
983 Format: <full_path>
984 Run specified binary instead of /sbin/init as init
985 process.
986
987 initcall_debug [KNL] Trace initcalls as they are executed. Useful
988 for working out where the kernel is dying during
989 startup.
990
991 initrd= [BOOT] Specify the location of the initial ramdisk
992
993 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
994 Format: <irq>
995
ba395927 996 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
0cd5c3c8
KM
997 on
998 Enable intel iommu driver.
ba395927
KA
999 off
1000 Disable intel iommu driver.
1001 igfx_off [Default Off]
1002 By default, gfx is mapped as normal device. If a gfx
1003 device has a dedicated DMAR unit, the DMAR unit is
1004 bypassed by not enabling DMAR with this option. In
1005 this case, gfx device will use physical address for
1006 DMA.
7d3b03ce
KA
1007 forcedac [x86_64]
1008 With this option iommu will not optimize to look
1009 for io virtual address below 32 bit forcing dual
1010 address cycle on pci bus for cards supporting greater
1011 than 32 bit addressing. The default is to look
1012 for translation below 32 bit and if not available
1013 then look in the higher range.
5e0d2a6f 1014 strict [Default Off]
1015 With this option on every unmap_single operation will
1016 result in a hardware IOTLB flush operation as opposed
1017 to batching them for performance.
ba395927 1018
0cb55ad2
RD
1019 inttest= [IA64]
1020
1021 iomem= Disable strict checking of access to MMIO memory
1022 strict regions from userspace.
1023 relaxed
1024
1025 iommu= [x86]
1026 off
1027 force
1028 noforce
1029 biomerge
1030 panic
1031 nopanic
1032 merge
1033 nomerge
1034 forcesac
1035 soft
4ed0d3e6 1036 pt [x86, IA64]
0cb55ad2
RD
1037
1038 io7= [HW] IO7 for Marvel based alpha systems
1039 See comment before marvel_specify_io7 in
1040 arch/alpha/kernel/core_marvel.c.
1041
6cececfc 1042 io_delay= [X86] I/O delay method
6e7c4025
IM
1043 0x80
1044 Standard port 0x80 based delay
1045 0xed
1046 Alternate port 0xed based delay (needed on some systems)
b02aae9c 1047 udelay
6e7c4025
IM
1048 Simple two microseconds delay
1049 none
1050 No delay
b02aae9c 1051
1da177e4 1052 ip= [IP_PNP]
dc7a0816 1053 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1054
1055 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
1056 See comment before ip2_setup() in
1057 drivers/char/ip2/ip2base.c.
1da177e4
LT
1058
1059 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1060 See header of drivers/scsi/ips.c.
1061
200803df
AC
1062 irqfixup [HW]
1063 When an interrupt is not handled search all handlers
1064 for it. Intended to get systems with badly broken
1065 firmware running.
1066
1067 irqpoll [HW]
1068 When an interrupt is not handled search all handlers
1069 for it. Also check all handlers each timer
1070 interrupt. Intended to get systems with badly broken
1071 firmware running.
1072
1da177e4 1073 isapnp= [ISAPNP]
a9913044 1074 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
1075
1076 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
1077 Format:
1078 <cpu number>,...,<cpu number>
1079 or
b225d44e
LZ
1080 <cpu number>-<cpu number>
1081 (must be a positive range in ascending order)
22f2e280
DF
1082 or a mixture
1083 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 1084
1da177e4
LT
1085 This option can be used to specify one or more CPUs
1086 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
1087 algorithms. You can move a process onto or off an
1088 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
1089 <cpu number> begins at 0 and the maximum value is
1090 "number of CPUs in system - 1".
1091
1092 This option is the preferred way to isolate CPUs. The
a9913044
RD
1093 alternative -- manually setting the CPU mask of all
1094 tasks in the system -- can cause problems and
1095 suboptimal load balancer performance.
1da177e4 1096
a9913044 1097 iucv= [HW,NET]
1da177e4
LT
1098
1099 js= [HW,JOY] Analog joystick
1100 See Documentation/input/joystick.txt.
1101
0cb55ad2
RD
1102 keepinitrd [HW,ARM]
1103
6cececfc 1104 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
ed7ed365
MG
1105 specifies the amount of memory usable by the kernel
1106 for non-movable allocations. The requested amount is
1107 spread evenly throughout all nodes in the system. The
1108 remaining memory in each node is used for Movable
1109 pages. In the event, a node is too small to have both
1110 kernelcore and Movable pages, kernelcore pages will
1111 take priority and other nodes will have a larger number
1112 of kernelcore pages. The Movable zone is used for the
1113 allocation of pages that may be reclaimed or moved
1114 by the page migration subsystem. This means that
1115 HugeTLB pages may not be allocated from this zone.
1116 Note that allocations like PTEs-from-HighMem still
1117 use the HighMem zone if it exists, and the Normal
1118 zone if it does not.
1119
6cdf6e06
JW
1120 kgdboc= [HW] kgdb over consoles.
1121 Requires a tty driver that supports console polling.
19f59460 1122 (only serial supported for now)
6cdf6e06
JW
1123 Format: <serial_device>[,baud]
1124
9bed90c6
FF
1125 kmac= [MIPS] korina ethernet MAC address.
1126 Configure the RouterBoard 532 series on-chip
1127 Ethernet adapter MAC address.
1128
04f70336
CM
1129 kmemleak= [KNL] Boot-time kmemleak enable/disable
1130 Valid arguments: on, off
1131 Default: on
1132
6cececfc 1133 kstack=N [X86] Print N words from the kernel stack
0cb55ad2
RD
1134 in oops dumps.
1135
fef07aae
AP
1136 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1137 Default is 0 (don't ignore, but inject #GP)
1138
1139 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1140 Default is 1 (enabled)
1141
1142 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1143 Default is 0 (off)
1144
1145 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1146 for all guests.
1147 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1148
1149 kvm-intel.bypass_guest_pf=
1150 [KVM,Intel] Disables bypassing of guest page faults
1151 on Intel chips. Default is 1 (enabled)
1152
1153 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1154 (virtualized MMU) support on capable Intel chips.
1155 Default is 1 (enabled)
1156
1157 kvm-intel.emulate_invalid_guest_state=
1158 [KVM,Intel] Enable emulation of invalid guest states
1159 Default is 0 (disabled)
1160
1161 kvm-intel.flexpriority=
1162 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1163 Default is 1 (enabled)
1164
1165 kvm-intel.unrestricted_guest=
1166 [KVM,Intel] Disable unrestricted guest feature
1167 (virtualized real and unpaged mode) on capable
1168 Intel chips. Default is 1 (enabled)
1169
1170 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1171 feature (tagged TLBs) on capable Intel chips.
1172 Default is 1 (enabled)
1173
1da177e4
LT
1174 l2cr= [PPC]
1175
a78bfbfc
RB
1176 l3cr= [PPC]
1177
cd4f0ef7 1178 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1179 disabled it.
1da177e4 1180
6cececfc 1181 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
ada9cfdd 1182 in C2 power state.
e585bef8 1183
fcb71f6f
FC
1184 libata.dma= [LIBATA] DMA control
1185 libata.dma=0 Disable all PATA and SATA DMA
1186 libata.dma=1 PATA and SATA Disk DMA only
1187 libata.dma=2 ATAPI (CDROM) DMA only
1188 libata.dma=4 Compact Flash DMA only
1189 Combinations also work, so libata.dma=3 enables DMA
1190 for disks and CDROMs, but not CFs.
20308871
MP
1191
1192 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1193 libata.ignore_hpa=0 keep BIOS limits (default)
1194 libata.ignore_hpa=1 ignore limits, using full disk
fcb71f6f 1195
78e70c23
DJ
1196 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1197 when set.
1198 Format: <int>
1199
33267325
TH
1200 libata.force= [LIBATA] Force configurations. The format is comma
1201 separated list of "[ID:]VAL" where ID is
1202 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1203 matching port, link or device. Basically, it matches
1204 the ATA ID string printed on console by libata. If
1205 the whole ID part is omitted, the last PORT and DEVICE
1206 values are used. If ID hasn't been specified yet, the
1207 configuration applies to all ports, links and devices.
1208
1209 If only DEVICE is omitted, the parameter applies to
1210 the port and all links and devices behind it. DEVICE
1211 number of 0 either selects the first device or the
1212 first fan-out link behind PMP device. It does not
1213 select the host link. DEVICE number of 15 selects the
1214 host link and device attached to it.
1215
1216 The VAL specifies the configuration to force. As long
1217 as there's no ambiguity shortcut notation is allowed.
1218 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1219 The following configurations can be forced.
1220
1221 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1222 Any ID with matching PORT is used.
1223
1224 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1225
1226 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1227 udma[/][16,25,33,44,66,100,133] notation is also
1228 allowed.
1229
1230 * [no]ncq: Turn on or off NCQ.
1231
05944bdf
TH
1232 * nohrst, nosrst, norst: suppress hard, soft
1233 and both resets.
1234
33267325
TH
1235 If there are multiple matching configurations changing
1236 the same attribute, the last one is used.
1237
7c4be253
RD
1238 lmb=debug [KNL] Enable lmb debug messages.
1239
1da177e4 1240 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1241 See Documentation/blockdev/ramdisk.txt.
1da177e4 1242
a6b25b67
RD
1243 lockd.nlm_grace_period=P [NFS] Assign grace period.
1244 Format: <integer>
1da177e4 1245
a6b25b67
RD
1246 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1247 Format: <integer>
1248
1249 lockd.nlm_timeout=T [NFS] Assign timeout value.
1250 Format: <integer>
1251
1252 lockd.nlm_udpport=M [NFS] Assign UDP port.
1253 Format: <integer>
1da177e4
LT
1254
1255 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1256 Format: <irq>
1257
1258 loglevel= All Kernel Messages with a loglevel smaller than the
1259 console loglevel will be printed to the console. It can
1260 also be changed with klogd or other programs. The
1261 loglevels are defined as follows:
1262
1263 0 (KERN_EMERG) system is unusable
1264 1 (KERN_ALERT) action must be taken immediately
1265 2 (KERN_CRIT) critical conditions
1266 3 (KERN_ERR) error conditions
1267 4 (KERN_WARNING) warning conditions
1268 5 (KERN_NOTICE) normal but significant condition
1269 6 (KERN_INFO) informational
1270 7 (KERN_DEBUG) debug-level messages
1271
1272 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1273 Format: { n | nk | nM }
1274 n must be a power of two. The default size
1275 is set in the kernel config file.
1da177e4 1276
accaa24c
RD
1277 logo.nologo [FB] Disables display of the built-in Linux logo.
1278 This may be used to provide more screen space for
1279 kernel log messages and is useful when debugging
1280 kernel boot problems.
1281
1da177e4
LT
1282 lp=0 [LP] Specify parallel ports to use, e.g,
1283 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1284 lp=reset first parallel port). 'lp=0' disables the
1285 lp=auto printer driver. 'lp=reset' (which can be
1286 specified in addition to the ports) causes
1287 attached printers to be reset. Using
1288 lp=port1,port2,... specifies the parallel ports
1289 to associate lp devices with, starting with
1290 lp0. A port specification may be 'none' to skip
1291 that lp device, or a parport name such as
1292 'parport0'. Specifying 'lp=auto' instead of a
1293 port specification list means that device IDs
1294 from each port should be examined, to see if
1295 an IEEE 1284-compliant printer is attached; if
1296 so, the driver will manage that printer.
1297 See also header of drivers/char/lp.c.
1298
1299 lpj=n [KNL]
1300 Sets loops_per_jiffy to given constant, thus avoiding
1301 time-consuming boot-time autodetection (up to 250 ms per
1302 CPU). 0 enables autodetection (default). To determine
1303 the correct value for your kernel, boot with normal
1304 autodetection and see what value is printed. Note that
1305 on SMP systems the preset will be applied to all CPUs,
1306 which is likely to cause problems if your CPUs need
1307 significantly divergent settings. An incorrect value
1308 will cause delays in the kernel to be wrong, leading to
1309 unpredictable I/O errors and other breakage. Although
1310 unlikely, in the extreme case this might damage your
1311 hardware.
1312
1313 ltpc= [NET]
1314 Format: <io>,<irq>,<dma>
1315
a9913044
RD
1316 mac5380= [HW,SCSI] Format:
1317 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1318
a9913044
RD
1319 machvec= [IA64] Force the use of a particular machine-vector
1320 (machvec) in a generic kernel.
1321 Example: machvec=hpzx1_swiotlb
1da177e4 1322
3209e70e
WZ
1323 machtype= [Loongson] Share the same kernel image file between different
1324 yeeloong laptop.
1325 Example: machtype=lemote-yeeloong-2f-7inch
1326
0cb55ad2
RD
1327 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1328 than or equal to this physical address is ignored.
1da177e4
LT
1329
1330 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1331 should make use of. maxcpus=n : n >= 0 limits the
1332 kernel to using 'n' processors. n=0 is a special case,
1333 it is equivalent to "nosmp", which also disables
1334 the IO APIC.
1da177e4 1335
0cb55ad2
RD
1336 max_loop= [LOOP] Maximum number of loopback devices that can
1337 be mounted
1338 Format: <1-256>
2b2c3750 1339
a9913044 1340 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1341 Should be between 1 and 2^32-1.
1342
1343 max_report_luns=
a9913044 1344 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1345 Should be between 1 and 16384.
1346
1da177e4
LT
1347 mcatest= [IA-64]
1348
cd4f0ef7 1349 mce [X86-32] Machine Check Exception
1da177e4 1350
71cced6e 1351 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1352
1da177e4
LT
1353 md= [HW] RAID subsystems devices and level
1354 See Documentation/md.txt.
a9913044 1355
1da177e4
LT
1356 mdacon= [MDA]
1357 Format: <first>,<last>
1358 Specifies range of consoles to be captured by the MDA.
a9913044 1359
1da177e4
LT
1360 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1361 Amount of memory to be used when the kernel is not able
1362 to see the whole system memory or for test.
cd4f0ef7 1363 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1364 address space collisions. Without memmap= PCI devices
1365 could be placed at addresses belonging to unused RAM.
1366
cd4f0ef7 1367 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1368 memory.
1369
6902aa84
PM
1370 memchunk=nn[KMG]
1371 [KNL,SH] Allow user to override the default size for
1372 per-device physically contiguous DMA buffers.
1373
6cececfc 1374 memmap=exactmap [KNL,X86] Enable setting of an exact
1da177e4
LT
1375 E820 memory map, as specified by the user.
1376 Such memmap=exactmap lines can be constructed based on
1377 BIOS output or other requirements. See the memmap=nn@ss
1378 option description.
1379
1380 memmap=nn[KMG]@ss[KMG]
1381 [KNL] Force usage of a specific region of memory
1382 Region of memory to be used, from ss to ss+nn.
1383
1384 memmap=nn[KMG]#ss[KMG]
1385 [KNL,ACPI] Mark specific memory as ACPI data.
1386 Region of memory to be used, from ss to ss+nn.
1387
1388 memmap=nn[KMG]$ss[KMG]
1389 [KNL,ACPI] Mark specific memory as reserved.
1390 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1391 Example: Exclude memory from 0x18690000-0x1869ffff
1392 memmap=64K$0x18690000
1393 or
1394 memmap=0x10000$0x18690000
1da177e4 1395
9f077871
JF
1396 memory_corruption_check=0/1 [X86]
1397 Some BIOSes seem to corrupt the first 64k of
1398 memory when doing things like suspend/resume.
1399 Setting this option will scan the memory
1400 looking for corruption. Enabling this will
1401 both detect corruption and prevent the kernel
1402 from using the memory being corrupted.
1403 However, its intended as a diagnostic tool; if
1404 repeatable BIOS-originated corruption always
1405 affects the same memory, you can use memmap=
1406 to prevent the kernel from using that memory.
1407
1408 memory_corruption_check_size=size [X86]
1409 By default it checks for corruption in the low
1410 64k, making this memory unavailable for normal
1411 use. Use this parameter to scan for
1412 corruption in more or less memory.
1413
1414 memory_corruption_check_period=seconds [X86]
1415 By default it checks for corruption every 60
1416 seconds. Use this parameter to check at some
1417 other rate. 0 disables periodic checking.
1418
caadbdce 1419 memtest= [KNL,X86] Enable memtest
c64df707 1420 Format: <integer>
c64df707 1421 default : 0 <disable>
9e5f6cf5
AH
1422 Specifies the number of memtest passes to be
1423 performed. Each pass selects another test
1424 pattern from a given set of patterns. Memtest
1425 fills the memory with this pattern, validates
1426 memory contents and reserves bad memory
1427 regions that are detected.
c64df707 1428
1da177e4
LT
1429 meye.*= [HW] Set MotionEye Camera parameters
1430 See Documentation/video4linux/meye.txt.
1431
8f36881b
AS
1432 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1433 Multi-Function General Purpose Timers on AMD Geode
1434 platforms.
1435
e6c4dc6c
WT
1436 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1437 the BIOS has incorrectly applied a workaround. TinyBIOS
1438 version 0.98 is known to be affected, 0.99 fixes the
1439 problem by letting the user disable the workaround.
1440
1da177e4
LT
1441 mga= [HW,DRM]
1442
1c207f95
RD
1443 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1444 physical address is ignored.
1445
39f45d7b
MP
1446 mini2440= [ARM,HW,KNL]
1447 Format:[0..2][b][c][t]
1448 Default: "0tb"
1449 MINI2440 configuration specification:
1450 0 - The attached screen is the 3.5" TFT
1451 1 - The attached screen is the 7" TFT
1452 2 - The VGA Shield is attached (1024x768)
1453 Leaving out the screen size parameter will not load
1454 the TFT driver, and the framebuffer will be left
1455 unconfigured.
1456 b - Enable backlight. The TFT backlight pin will be
1457 linked to the kernel VESA blanking code and a GPIO
1458 LED. This parameter is not necessary when using the
1459 VGA shield.
1460 c - Enable the s3c camera interface.
1461 t - Reserved for enabling touchscreen support. The
1462 touchscreen support is not enabled in the mainstream
1463 kernel as of 2.6.30, a preliminary port can be found
1464 in the "bleeding edge" mini2440 support kernel at
1465 http://repo.or.cz/w/linux-2.6/mini2440.git
1466
6b74ab97
MG
1467 mminit_loglevel=
1468 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1469 parameter allows control of the logging verbosity for
1470 the additional memory initialisation checks. A value
1471 of 0 disables mminit logging and a level of 4 will
1472 log everything. Information is printed at KERN_DEBUG
1473 so loglevel=8 may also need to be specified.
1474
1da177e4
LT
1475 mousedev.tap_time=
1476 [MOUSE] Maximum time between finger touching and
1477 leaving touchpad surface for touch to be considered
1478 a tap and be reported as a left button click (for
1479 touchpads working in absolute mode only).
1480 Format: <msecs>
1481 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1482 reporting absolute coordinates, such as tablets
1483 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1484 reporting absolute coordinates, such as tablets
1485
6cececfc 1486 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
0cb55ad2
RD
1487 is similar to kernelcore except it specifies the
1488 amount of memory used for migratable allocations.
1489 If both kernelcore and movablecore is specified,
1490 then kernelcore will be at *least* the specified
1491 value but may be more. If movablecore on its own
1492 is specified, the administrator must be careful
1493 that the amount of memory usable for all allocations
1494 is not too small.
1495
1da177e4
LT
1496 mpu401= [HW,OSS]
1497 Format: <io>,<irq>
1498
1499 MTD_Partition= [MTD]
1500 Format: <name>,<region-number>,<size>,<offset>
1501
a9913044
RD
1502 MTD_Region= [MTD] Format:
1503 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1504
1505 mtdparts= [MTD]
c8facbb6 1506 See drivers/mtd/cmdlinepart.c.
1da177e4 1507
5988af23
RH
1508 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1509
1510 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1511
1512 boundary - index of last SLC block on Flex-OneNAND.
1513 The remaining blocks are configured as MLC blocks.
1514 lock - Configure if Flex-OneNAND boundary should be locked.
1515 Once locked, the boundary cannot be changed.
1516 1 indicates lock status, 0 indicates unlock status.
1517
9db829f4
BD
1518 mtdset= [ARM]
1519 ARM/S3C2412 JIVE boot control
1520
1521 See arch/arm/mach-s3c2412/mach-jive.c
1522
1da177e4 1523 mtouchusb.raw_coordinates=
a9913044
RD
1524 [HW] Make the MicroTouch USB driver use raw coordinates
1525 ('y', default) or cooked coordinates ('n')
1da177e4 1526
0cb55ad2 1527 mtrr_chunk_size=nn[KMG] [X86]
19f59460 1528 used for mtrr cleanup. It is largest continuous chunk
0cb55ad2
RD
1529 that could hold holes aka. UC entries.
1530
1531 mtrr_gran_size=nn[KMG] [X86]
1532 Used for mtrr cleanup. It is granularity of mtrr block.
1533 Default is 1.
1534 Large value could prevent small alignment from
1535 using up MTRRs.
1536
1537 mtrr_spare_reg_nr=n [X86]
1538 Format: <integer>
1539 Range: 0,7 : spare reg number
1540 Default : 1
1541 Used for mtrr cleanup. It is spare mtrr entries number.
1542 Set to 2 or more if your graphical card needs more.
1543
1da177e4
LT
1544 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1545
1546 NCR_D700= [HW,SCSI]
1547 See header of drivers/scsi/NCR_D700.c.
1548
1549 ncr5380= [HW,SCSI]
1550
1551 ncr53c400= [HW,SCSI]
1552
1553 ncr53c400a= [HW,SCSI]
1554
1555 ncr53c406a= [HW,SCSI]
1556
1557 ncr53c8xx= [HW,SCSI]
1558
1559 netdev= [NET] Network devices parameters
1560 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1561 Note that mem_start is often overloaded to mean
1562 something different and driver-specific.
a9913044
RD
1563 This usage is only documented in each driver source
1564 file if at all.
1565
58401572
KPO
1566 nf_conntrack.acct=
1567 [NETFILTER] Enable connection tracking flow accounting
1568 0 to disable accounting
1569 1 to enable accounting
1570 Default value depends on CONFIG_NF_CT_ACCT that is
1571 going to be removed in 2.6.29.
1572
1da177e4 1573 nfsaddrs= [NFS]
dc7a0816 1574 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1575
1576 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
dc7a0816 1577 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4 1578
a72b4422
TM
1579 nfs.callback_tcpport=
1580 [NFS] set the TCP port on which the NFSv4 callback
1581 channel should listen.
1582
e571cbf1
TM
1583 nfs.cache_getent=
1584 [NFS] sets the pathname to the program which is used
1585 to update the NFS client cache entries.
1586
1587 nfs.cache_getent_timeout=
1588 [NFS] sets the timeout after which an attempt to
1589 update a cache entry is deemed to have failed.
1590
58df095b
TM
1591 nfs.idmap_cache_timeout=
1592 [NFS] set the maximum lifetime for idmapper cache
1593 entries.
1594
f43bf0be
TM
1595 nfs.enable_ino64=
1596 [NFS] enable 64-bit inode numbers.
1597 If zero, the NFS client will fake up a 32-bit inode
1598 number for the readdir() and stat() syscalls instead
1599 of returning the full 64-bit number.
1600 The default is to return 64-bit inode numbers.
1601
1e1030dc 1602 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
e7ba176b
HS
1603 when a NMI is triggered.
1604 Format: [state][,regs][,debounce][,die]
1605
6cececfc 1606 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
5b9a0e14
CG
1607 Format: [panic,][num]
1608 Valid num: 0,1,2
1609 0 - turn nmi_watchdog off
1610 1 - use the IO-APIC timer for the NMI watchdog
1611 2 - use the local APIC for the NMI watchdog using
0cb55ad2
RD
1612 a performance counter. Note: This will use one
1613 performance counter and the local APIC's performance
1614 vector.
1615 When panic is specified, panic when an NMI watchdog
1616 timeout occurs.
1617 This is useful when you use a panic=... timeout and
1618 need the box quickly up again.
5b9a0e14
CG
1619 Instead of 1 and 2 it is possible to use the following
1620 symbolic names: lapic and ioapic
1621 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1da177e4 1622
bff38771
AV
1623 netpoll.carrier_timeout=
1624 [NET] Specifies amount of time (in seconds) that
1625 netpoll should wait for a carrier. By default netpoll
1626 waits 4 seconds.
1627
cd4f0ef7 1628 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1629 emulation library even if a 387 maths coprocessor
1630 is present.
1631
0cb55ad2
RD
1632 no_console_suspend
1633 [HW] Never suspend the console
1634 Disable suspending of consoles during suspend and
1635 hibernate operations. Once disabled, debugging
1636 messages can reach various consoles while the rest
1637 of the system is being put to sleep (ie, while
1638 debugging driver suspend/resume hooks). This may
1639 not work reliably with all consoles, but is known
1640 to work with serial and VGA consoles.
1641
c1aee215
CL
1642 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1643 caches in the slab allocator. Saves per-node memory,
1644 but will impact performance.
3395ee05 1645
a9913044
RD
1646 noalign [KNL,ARM]
1647
1da177e4
LT
1648 noapic [SMP,APIC] Tells the kernel to not make use of any
1649 IOAPICs that may be present in the system.
1650
1da177e4
LT
1651 nobats [PPC] Do not use BATs for mapping kernel lowmem
1652 on "Classic" PPC cores.
1653
1654 nocache [ARM]
a9913044 1655
0cb55ad2
RD
1656 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1657
163ecdff
SN
1658 nodelayacct [KNL] Disable per-task delay accounting
1659
1da177e4
LT
1660 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1661
6902aa84
PM
1662 nodsp [SH] Disable hardware DSP at boot time.
1663
6cececfc 1664 noefi [X86] Disable EFI runtime services support.
8b2cb7a8 1665
1da177e4
LT
1666 noexec [IA-64]
1667
6cececfc 1668 noexec [X86]
f5a1b191 1669 On X86-32 available only on PAE configured kernels.
1da177e4 1670 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1671 noexec=off: disable non-executable mappings
1672
1673 noexec32 [X86-64]
1674 This affects only 32-bit executables.
1675 noexec32=on: enable non-executable mappings (default)
1676 read doesn't imply executable mappings
1677 noexec32=off: disable non-executable mappings
1678 read implies executable mappings
1da177e4 1679
6902aa84
PM
1680 nofpu [SH] Disable hardware FPU at boot time.
1681
cd4f0ef7 1682 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1683 register save and restore. The kernel will only save
1684 legacy floating-point registers on task switch.
1da177e4 1685
0c752a93
SS
1686 noxsave [BUGS=X86] Disables x86 extended register state save
1687 and restore using xsave. The kernel will fallback to
1688 enabling legacy floating-point and sse state.
1689
01a24d2b
PZ
1690 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1691 wfi(ARM) instruction doesn't work correctly and not to
1692 use it. This is also useful when using JTAG debugger.
a9913044 1693
cd4f0ef7 1694 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1695 instruction doesn't work correctly and not to
1696 use it.
1697
1f29fae2
SH
1698 no_file_caps Tells the kernel not to honor file capabilities. The
1699 only way then for a file to be executed with privilege
1700 is to be setuid root or executed by root.
1701
1da177e4
LT
1702 nohalt [IA-64] Tells the kernel not to use the power saving
1703 function PAL_HALT_LIGHT when idle. This increases
1704 power-consumption. On the positive side, it reduces
1705 interrupt wake-up latency, which may improve performance
1706 in certain environments such as networked servers or
1707 real-time systems.
1708
79bf2bb3
TG
1709 nohz= [KNL] Boottime enable/disable dynamic ticks
1710 Valid arguments: on, off
1711 Default: on
1712
eeee7853
PM
1713 noiotrap [SH] Disables trapped I/O port accesses.
1714
cd4f0ef7 1715 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1716 disable unhandled interrupt sources.
1717
6cececfc 1718 no_timer_check [X86,APIC] Disables the code which tests for
8542b200
ZA
1719 broken timer IRQ sources.
1720
1da177e4
LT
1721 noisapnp [ISAPNP] Disables ISA PnP code.
1722
1723 noinitrd [RAM] Tells the kernel not to load any configured
1724 initial RAM disk.
1725
03ea8155
WH
1726 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1727 remapping.
1728
1da177e4
LT
1729 nointroute [IA-64]
1730
0aa366f3
TL
1731 nojitter [IA64] Disables jitter checking for ITC timers.
1732
cd4f0ef7 1733 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1734
cd4f0ef7 1735 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1736
1da177e4
LT
1737 noltlbs [PPC] Do not use large page/tlb entries for kernel
1738 lowmem mapping on PPC40x.
1739
312f1f01
H
1740 nomca [IA-64] Disable machine check abort handling
1741
cd4f0ef7 1742 nomce [X86-32] Machine Check Exception
abe37e5a 1743
83d7384f
AS
1744 nomfgpt [X86-32] Disable Multi-Function General Purpose
1745 Timer usage (for AMD Geode machines).
1746
016ddd9b
JK
1747 nopat [X86] Disable PAT (page attribute table extension of
1748 pagetables) support.
1749
0cb55ad2
RD
1750 norandmaps Don't use address space randomization. Equivalent to
1751 echo 0 > /proc/sys/kernel/randomize_va_space
1752
cd4f0ef7 1753 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1754
cd4f0ef7 1755 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1756 with UP alternatives
1757
1da177e4
LT
1758 noresidual [PPC] Don't use residual data on PReP machines.
1759
a9913044
RD
1760 noresume [SWSUSP] Disables resume and restores original swap
1761 space.
1762
1da177e4
LT
1763 no-scroll [VGA] Disables scrollback.
1764 This is required for the Braillex ib80-piezo Braille
1765 reader made by F.H. Papenmeier (Germany).
1766
1767 nosbagart [IA-64]
1768
cd4f0ef7 1769 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1770
61ec7567
LB
1771 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1772 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1773
97842216
DJ
1774 nosoftlockup [KNL] Disable the soft-lockup detector.
1775
c077719b 1776 noswapaccount [KNL] Disable accounting of swap in memory resource
21acb9ca 1777 controller. (See Documentation/cgroups/memory.txt)
c077719b 1778
1da177e4
LT
1779 nosync [HW,M68K] Disables sync negotiation for all devices.
1780
cd4f0ef7 1781 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1782
1783 nousb [USB] Disable the USB subsystem
1784
1785 nowb [ARM]
a9913044 1786
2b2fd87a
WH
1787 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1788
a6c75b86
FY
1789 nptcg= [IA64] Override max number of concurrent global TLB
1790 purges which is reported from either PAL_VM_SUMMARY or
1791 SAL PALO.
1792
2b633e3f
YL
1793 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1794 could support. nr_cpus=n : n >= 1 limits the kernel to
1795 supporting 'n' processors. Later in runtime you can not
1796 use hotplug cpu feature to put more cpu back to online.
1797 just like you compile the kernel NR_CPUS=n
1798
0cb55ad2
RD
1799 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1800
f0c0b2b8
KH
1801 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1802 one of ['zone', 'node', 'default'] can be specified
1803 This can be set from sysctl after boot.
1804 See Documentation/sysctl/vm.txt for details.
1805
7c4be253
RD
1806 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1807 See Documentation/debugging-via-ohci1394.txt for more
1808 info.
1809
3ef0e1f8
AS
1810 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1811 Rather than timing out after 20 ms if an EC
1812 command is not properly ACKed, override the length
1813 of the timeout. We have interrupts disabled while
1814 waiting for the ACK, so if this is set too high
1815 interrupts *may* be lost!
1816
15ac7afe
TL
1817 omap_mux= [OMAP] Override bootloader pin multiplexing.
1818 Format: <mux_mode0.mode_name=value>...
1819 For example, to override I2C bus2:
1820 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1821
1da177e4
LT
1822 opl3= [HW,OSS]
1823 Format: <io>
1824
1da177e4
LT
1825 oprofile.timer= [HW]
1826 Use timer interrupt instead of performance counters
1827
7e4e0bd5
RR
1828 oprofile.cpu_type= Force an oprofile cpu type
1829 This might be useful if you have an older oprofile
1830 userland or if you want common events.
8d7ff4f2
RR
1831 Format: { arch_perfmon }
1832 arch_perfmon: [X86] Force use of architectural
7e4e0bd5
RR
1833 perfmon on Intel CPUs instead of the
1834 CPU specific event set.
1dcdb5a9 1835
1da177e4
LT
1836 osst= [HW,SCSI] SCSI Tape Driver
1837 Format: <buffer_size>,<write_threshold>
1838 See also Documentation/scsi/st.txt.
1839
1840 panic= [KNL] Kernel behaviour on panic
1841 Format: <timeout>
1842
1843 parkbd.port= [HW] Parallel port number the keyboard adapter is
1844 connected to, default is 0.
1845 Format: <parport#>
1846 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1847 0 for XT, 1 for AT (default is AT).
a9913044
RD
1848 Format: <mode>
1849
1850 parport= [HW,PPT] Specify parallel ports. 0 disables.
1851 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1852 Use 'auto' to force the driver to use any
1853 IRQ/DMA settings detected (the default is to
1854 ignore detected IRQ/DMA settings because of
1855 possible conflicts). You can specify the base
1856 address, IRQ, and DMA settings; IRQ and DMA
1857 should be numbers, or 'auto' (for using detected
1858 settings on that particular port), or 'nofifo'
1859 (to avoid using a FIFO even if it is detected).
1860 Parallel ports are assigned in the order they
1861 are specified on the command line, starting
1862 with parport0.
1863
1864 parport_init_mode= [HW,PPT]
1865 Configure VIA parallel port to operate in
1866 a specific mode. This is necessary on Pegasos
1867 computer where firmware has no options for setting
1868 up parallel port mode and sets it to spp.
1869 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1870 Format: [spp|ps2|epp|ecp|ecpepp]
1871
a9913044
RD
1872 pas2= [HW,OSS] Format:
1873 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1874
1da177e4
LT
1875 pas16= [HW,SCSI]
1876 See header of drivers/scsi/pas16.c.
1877
dd287796
AM
1878 pause_on_oops=
1879 Halt all CPUs after the first oops has been printed for
1880 the specified number of seconds. This is to be used if
1881 your oopses keep scrolling off the screen.
1882
1da177e4
LT
1883 pcbit= [HW,ISDN]
1884
1885 pcd. [PARIDE]
1886 See header of drivers/block/paride/pcd.c.
31c00fc1 1887 See also Documentation/blockdev/paride.txt.
1da177e4 1888
a9913044 1889 pci=option[,option...] [PCI] various PCI subsystem options:
1cc0ca26
BH
1890 earlydump [X86] dump PCI config space before the kernel
1891 changes anything
c0115606 1892 off [X86] don't probe for the PCI bus
cd4f0ef7 1893 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1894 the hardware directly. Use this if your machine
1895 has a non-standard PCI host bridge.
cd4f0ef7 1896 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1897 hardware access methods are allowed. Use this
1898 if you experience crashes upon bootup and you
1899 suspect they are caused by the BIOS.
c0115606 1900 conf1 [X86] Force use of PCI Configuration
a9913044 1901 Mechanism 1.
c0115606 1902 conf2 [X86] Force use of PCI Configuration
a9913044 1903 Mechanism 2.
7f785763
RD
1904 noaer [PCIE] If the PCIEAER kernel config parameter is
1905 enabled, this kernel boot option can be used to
1906 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1907 nodomains [PCI] Disable support for multiple PCI
1908 root domains (aka PCI segments, in ACPI-speak).
6cececfc 1909 nommconf [X86] Disable use of MMCONFIG for PCI
61be6d66 1910 Configuration
12983077
AH
1911 check_enable_amd_mmconf [X86] check for and enable
1912 properly configured MMIO access to PCI
1913 config space on AMD family 10h CPU
309e57df
MW
1914 nomsi [MSI] If the PCI_MSI kernel config parameter is
1915 enabled, this kernel boot option can be used to
1916 disable the use of MSI interrupts system-wide.
a9322f64
SA
1917 noioapicquirk [APIC] Disable all boot interrupt quirks.
1918 Safety option to keep boot IRQs enabled. This
1919 should never be necessary.
9197979b
SA
1920 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1921 primary IO-APIC for bridges that cannot disable
1922 boot IRQs. This fixes a source of spurious IRQs
1923 when the system masks IRQs.
41b9eb26
SA
1924 noioapicreroute [APIC] Disable workaround that uses the
1925 boot IRQ equivalent of an IRQ that connects to
1926 a chipset where boot IRQs cannot be disabled.
1927 The opposite of ioapicreroute.
cd4f0ef7 1928 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1929 routing table. These calls are known to be buggy
1930 on several machines and they hang the machine
1931 when used, but on other computers it's the only
1932 way to get the interrupt routing table. Try
1933 this option if the kernel is unable to allocate
1934 IRQs or discover secondary PCI buses on your
1935 motherboard.
c0115606 1936 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1937 Use with caution as certain devices share
1938 address decoders between ROMs and other
1939 resources.
c0115606 1940 norom [X86] Do not assign address space to
bb71ad88
GH
1941 expansion ROMs that do not already have
1942 BIOS assigned address ranges.
c0115606 1943 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1944 assigned automatically to PCI devices. You can
1945 make the kernel exclude IRQs of your ISA cards
1946 this way.
c0115606 1947 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1948 of the PIRQ table (normally generated
1949 by the BIOS) if it is outside the
1950 F0000h-100000h range.
c0115606 1951 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1952 useful if the kernel is unable to find your
1953 secondary buses and you want to tell it
1954 explicitly which ones they are.
c0115606 1955 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1956 numbers ourselves, overriding
1957 whatever the firmware may have done.
c0115606 1958 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1959 in the BIOS $PIR table. This is needed on
1960 some systems with broken BIOSes, notably
1961 some HP Pavilion N5400 and Omnibook XE3
1962 notebooks. This will have no effect if ACPI
1963 IRQ routing is enabled.
c0115606 1964 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1965 or for PCI scanning.
7bc5e3f2
BH
1966 use_crs [X86] Use PCI host bridge window information
1967 from ACPI. On BIOSes from 2008 or later, this
1968 is enabled by default. If you need to use this,
1969 please report a bug.
1970 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1971 If you need to use this, please report a bug.
a9913044
RD
1972 routeirq Do IRQ routing for all PCI devices.
1973 This is normally done in pci_enable_device(),
1974 so this option is a temporary workaround
1975 for broken drivers that don't call it.
13a6ddb0
YL
1976 skip_isa_align [X86] do not align io start addr, so can
1977 handle more pci cards
a9913044
RD
1978 firmware [ARM] Do not re-enumerate the bus but instead
1979 just use the configuration from the
1980 bootloader. This is currently used on
1981 IXP2000 systems where the bus has to be
1982 configured a certain way for adjunct CPUs.
0637a70a
AK
1983 noearly [X86] Don't do any early type 1 scanning.
1984 This might help on some broken boards which
1985 machine check when some devices' config space
1986 is read. But various workarounds are disabled
1987 and some IOMMU drivers will not work.
6b4b78fe
MD
1988 bfsort Sort PCI devices into breadth-first order.
1989 This sorting is done to get a device
1990 order compatible with older (<= 2.4) kernels.
1991 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1992 cbiosize=nn[KMG] The fixed amount of bus space which is
1993 reserved for the CardBus bridge's IO window.
1994 The default value is 256 bytes.
1995 cbmemsize=nn[KMG] The fixed amount of bus space which is
1996 reserved for the CardBus bridge's memory
1997 window. The default value is 64 megabytes.
32a9a682
YS
1998 resource_alignment=
1999 Format:
2000 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2001 Specifies alignment and device to reassign
2002 aligned memory resources.
2003 If <order of align> is not specified,
2004 PAGE_SIZE is used as alignment.
2005 PCI-PCI bridge can be specified, if resource
2006 windows need to be expanded.
43c16408
AP
2007 ecrc= Enable/disable PCIe ECRC (transaction layer
2008 end-to-end CRC checking).
2009 bios: Use BIOS/firmware settings. This is the
2010 the default.
2011 off: Turn ECRC off
2012 on: Turn ECRC on.
6b4b78fe 2013
e5665a45
CE
2014 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2015 Management.
2016 off Disable ASPM.
2017 force Enable ASPM even on devices that claim not to support it.
2018 WARNING: Forcing ASPM on may cause system lockups.
2019
c7f48656
RW
2020 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2021 off Do not use native PCIe PME signaling.
2022 force Use native PCIe PME signaling even if the BIOS refuses
2023 to allow the kernel to control the relevant PCIe config
2024 registers.
c39fae14
RW
2025 nomsi Do not use MSI for native PCIe PME signaling (this makes
2026 all PCIe root ports use INTx for everything).
c7f48656 2027
1da177e4
LT
2028 pcmv= [HW,PCMCIA] BadgePAD 4
2029
2030 pd. [PARIDE]
31c00fc1 2031 See Documentation/blockdev/paride.txt.
1da177e4
LT
2032
2033 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2034 boot time.
2035 Format: { 0 | 1 }
2036 See arch/parisc/kernel/pdc_chassis.c
2037
f58dc01b 2038 percpu_alloc= Select which percpu first chunk allocator to use.
e933a73f
TH
2039 Currently supported values are "embed" and "page".
2040 Archs may support subset or none of the selections.
2041 See comments in mm/percpu.c for details on each
2042 allocator. This parameter is primarily for debugging
2043 and performance comparison.
fa8a7094 2044
1da177e4 2045 pf. [PARIDE]
31c00fc1 2046 See Documentation/blockdev/paride.txt.
1da177e4
LT
2047
2048 pg. [PARIDE]
31c00fc1 2049 See Documentation/blockdev/paride.txt.
1da177e4
LT
2050
2051 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 2052 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
2053
2054 plip= [PPT,NET] Parallel port network link
2055 Format: { parport<nr> | timid | 0 }
2056 See also Documentation/parport.txt.
2057
de32a243
TG
2058 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2059 Override pmtimer IOPort with a hex value.
2060 e.g. pmtmr=0x508
2061
97ef062b
BH
2062 pnp.debug [PNP]
2063 Enable PNP debug messages. This depends on the
2064 CONFIG_PNP_DEBUG_MESSAGES option.
2065
1da177e4
LT
2066 pnpacpi= [ACPI]
2067 { off }
2068
2069 pnpbios= [ISAPNP]
2070 { on | off | curr | res | no-curr | no-res }
2071
2072 pnp_reserve_irq=
2073 [ISAPNP] Exclude IRQs for the autoconfiguration
2074
2075 pnp_reserve_dma=
2076 [ISAPNP] Exclude DMAs for the autoconfiguration
2077
2078 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 2079 Ranges are in pairs (I/O port base and size).
1da177e4
LT
2080
2081 pnp_reserve_mem=
a9913044
RD
2082 [ISAPNP] Exclude memory regions for the
2083 autoconfiguration.
1da177e4
LT
2084 Ranges are in pairs (memory base and size).
2085
4af94f39
RD
2086 ports= [IP_VS_FTP] IPVS ftp helper module
2087 Default is 21.
2088 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2089 may be specified.
2090 Format: <port>,<port>....
2091
45807a1d
IM
2092 print-fatal-signals=
2093 [KNL] debug: print fatal signals
f84d49b2
NO
2094
2095 If enabled, warn about various signal handling
2096 related application anomalies: too many signals,
2097 too many POSIX.1 timers, fatal signals causing a
2098 coredump - etc.
2099
2100 If you hit the warning due to signal overflow,
2101 you might want to try "ulimit -i unlimited".
2102
45807a1d
IM
2103 default: off.
2104
e84845c4
RD
2105 printk.time= Show timing data prefixed to each printk message line
2106 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2107
0cb55ad2
RD
2108 processor.max_cstate= [HW,ACPI]
2109 Limit processor to maximum C-state
2110 max_cstate=9 overrides any DMI blacklist limit.
2111
2112 processor.nocst [HW,ACPI]
2113 Ignore the _CST method to determine C-states,
2114 instead using the legacy FADT method
2115
1da177e4 2116 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
2117 Format: [schedule,]<number>
2118 Param: "schedule" - profile schedule points.
2119 Param: <number> - step/bucket size as a power of 2 for
2120 statistical time based profiling.
b3da2a73
MG
2121 Param: "sleep" - profile D-state sleeping (millisecs).
2122 Requires CONFIG_SCHEDSTATS
c0fe2e69 2123 Param: "kvm" - profile VM exits.
1da177e4 2124
1da177e4
LT
2125 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2126 before loading.
31c00fc1 2127 See Documentation/blockdev/ramdisk.txt.
1da177e4 2128
a9913044
RD
2129 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2130 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
2131 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2132 per second.
a9913044
RD
2133 psmouse.resetafter= [HW,MOUSE]
2134 Try to reset the device after so many bad packets
1da177e4
LT
2135 (0 = never).
2136 psmouse.resolution=
2137 [HW,MOUSE] Set desired mouse resolution, in dpi.
2138 psmouse.smartscroll=
a9913044 2139 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
2140 0 = disabled, 1 = enabled (default).
2141
2142 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
2143 Format:
2144 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
2145
2146 pt. [PARIDE]
31c00fc1 2147 See Documentation/blockdev/paride.txt.
1da177e4 2148
dc8c8587
KS
2149 pty.legacy_count=
2150 [KNL] Number of legacy pty's. Overwrites compiled-in
2151 default number.
2152
7d2c502f 2153 quiet [KNL] Disable most log messages
a9913044 2154
1da177e4
LT
2155 r128= [HW,DRM]
2156
2157 raid= [HW,RAID]
2158 See Documentation/md.txt.
2159
a9913044 2160 ramdisk_blocksize= [RAM]
31c00fc1 2161 See Documentation/blockdev/ramdisk.txt.
a9913044 2162
1da177e4 2163 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 2164 See Documentation/blockdev/ramdisk.txt.
1da177e4 2165
24aaef8d
RD
2166 rcupdate.blimit= [KNL,BOOT]
2167 Set maximum number of finished RCU callbacks to process
2168 in one batch.
21a1ea9e 2169
24aaef8d
RD
2170 rcupdate.qhimark= [KNL,BOOT]
2171 Set threshold of queued
21a1ea9e
DS
2172 RCU callbacks over which batch limiting is disabled.
2173
24aaef8d
RD
2174 rcupdate.qlowmark= [KNL,BOOT]
2175 Set threshold of queued RCU callbacks below which
2176 batch limiting is re-enabled.
21a1ea9e 2177
ffdfc409
OJ
2178 rdinit= [KNL]
2179 Format: <full_path>
2180 Run specified binary instead of /init from the ramdisk,
2181 used for early userspace startup. See initrd.
2182
cd4f0ef7 2183 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 2184 Format: <reboot_mode>[,<reboot_mode2>[,...]]
ecb08d81 2185 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 2186
46b6d94e
PJ
2187 relax_domain_level=
2188 [KNL, SMP] Set scheduler's default relax_domain_level.
21acb9ca 2189 See Documentation/cgroups/cpusets.txt.
46b6d94e 2190
1da177e4
LT
2191 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2192
cd4f0ef7 2193 reservetop= [X86-32]
461a9aff
ZA
2194 Format: nn[KMG]
2195 Reserves a hole at the top of the kernel virtual
2196 address space.
2197
7e96287d
VG
2198 reset_devices [KNL] Force drivers to reset the underlying device
2199 during initialization.
2200
a9913044
RD
2201 resume= [SWSUSP]
2202 Specify the partition device for software suspend
1da177e4 2203
ecbd0da1
RW
2204 resume_offset= [SWSUSP]
2205 Specify the offset from the beginning of the partition
2206 given by "resume=" at which the swap header is located,
2207 in <PAGE_SIZE> units (needed only for swap files).
2208 See Documentation/power/swsusp-and-swap-files.txt
2209
0a7b35cb
MN
2210 retain_initrd [RAM] Keep initrd memory after extraction
2211
1da177e4
LT
2212 rhash_entries= [KNL,NET]
2213 Set number of hash buckets for route cache
2214
2215 riscom8= [HW,SERIAL]
2216 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2217
2218 ro [KNL] Mount root device read-only on boot
2219
2220 root= [KNL] Root filesystem
2221
2222 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2223 mount the root filesystem
2224
2225 rootflags= [KNL] Set root filesystem mount option string
2226
2227 rootfstype= [KNL] Set root filesystem type
2228
cc1ed754
PO
2229 rootwait [KNL] Wait (indefinitely) for root device to show up.
2230 Useful for devices that are detected asynchronously
2231 (e.g. USB and MMC devices).
2232
1da177e4
LT
2233 rw [KNL] Mount root device read-write on boot
2234
2235 S [KNL] Run init in single mode
2236
2237 sa1100ir [NET]
2238 See drivers/net/irda/sa1100_ir.c.
2239
1da177e4 2240 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 2241
f6630114
MT
2242 sched_debug [KNL] Enables verbose scheduler debug messages.
2243
1da177e4
LT
2244 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2245 Format: <io>[,<timeout>[,<isapnp>]]
2246
2247 scsi_debug_*= [SCSI]
2248 See drivers/scsi/scsi_debug.c.
2249
2250 scsi_default_dev_flags=
2251 [SCSI] SCSI default device flags
2252 Format: <integer>
2253
2254 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2255 Format: <vendor>:<model>:<flags>
2256 (flags are integer value)
2257
6af6632a
RD
2258 scsi_logging_level= [SCSI] a bit mask of logging levels
2259 See drivers/scsi/scsi_logging.h for bits. Also
2260 settable via sysctl at dev.scsi.logging_level
2261 (/proc/sys/dev/scsi/logging_level).
2262 There is also a nice 'scsi_logging_level' script in the
2263 S390-tools package, available for download at
2264 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 2265
3e082a91
MW
2266 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2267 discovered. async scans them in kernel threads,
2268 allowing boot to proceed. none ignores them, expecting
2269 user space to do the scan.
2270
0cb55ad2
RD
2271 security= [SECURITY] Choose a security module to enable at boot.
2272 If this boot parameter is not specified, only the first
2273 security module asking for security registration will be
2274 loaded. An invalid security module name will be treated
2275 as if no module has been chosen.
2276
2277 selinux= [SELINUX] Disable or enable SELinux at boot time.
1da177e4
LT
2278 Format: { "0" | "1" }
2279 See security/selinux/Kconfig help text.
2280 0 -- disable.
2281 1 -- enable.
2282 Default value is set via kernel config option.
2283 If enabled at boot time, /selinux/disable can be used
2284 later to disable prior to initial policy load.
2285
cd4f0ef7 2286 serialnumber [BUGS=X86-32]
1da177e4 2287
1da177e4
LT
2288 shapers= [NET]
2289 Maximal number of shapers.
a9913044 2290
b05f78f5
YL
2291 show_msr= [x86] show boot-time MSR settings
2292 Format: { <integer> }
2293 Show boot-time (BIOS-initialized) MSR settings.
2294 The parameter means the number of CPUs to show,
2295 for example 1 means boot CPU only.
2296
1da177e4
LT
2297 sim710= [SCSI,HW]
2298 See header of drivers/scsi/sim710.c.
2299
2300 simeth= [IA-64]
2301 simscsi=
a9913044 2302
1da177e4
LT
2303 slram= [HW,MTD]
2304
f0630fff
CL
2305 slub_debug[=options[,slabs]] [MM, SLUB]
2306 Enabling slub_debug allows one to determine the
2307 culprit if slab objects become corrupted. Enabling
2308 slub_debug can create guard zones around objects and
2309 may poison objects when not in use. Also tracks the
2310 last alloc / free. For more information see
2311 Documentation/vm/slub.txt.
c1aee215
CL
2312
2313 slub_max_order= [MM, SLUB]
f0630fff
CL
2314 Determines the maximum allowed order for slabs.
2315 A high setting may cause OOMs due to memory
2316 fragmentation. For more information see
2317 Documentation/vm/slub.txt.
c1aee215
CL
2318
2319 slub_min_objects= [MM, SLUB]
f0630fff
CL
2320 The minimum number of objects per slab. SLUB will
2321 increase the slab order up to slub_max_order to
2322 generate a sufficiently large slab able to contain
2323 the number of objects indicated. The higher the number
2324 of objects the smaller the overhead of tracking slabs
2325 and the less frequently locks need to be acquired.
c1aee215
CL
2326 For more information see Documentation/vm/slub.txt.
2327
2328 slub_min_order= [MM, SLUB]
2329 Determines the mininum page order for slabs. Must be
f0630fff 2330 lower than slub_max_order.
c1aee215
CL
2331 For more information see Documentation/vm/slub.txt.
2332
2333 slub_nomerge [MM, SLUB]
f0630fff 2334 Disable merging of slabs with similar size. May be
c1aee215 2335 necessary if there is some reason to distinguish
f0630fff
CL
2336 allocs to different slabs. Debug options disable
2337 merging on their own.
c1aee215
CL
2338 For more information see Documentation/vm/slub.txt.
2339
1da177e4
LT
2340 smart2= [HW]
2341 Format: <io1>[,<io2>[,...,<io8>]]
2342
cd4f0ef7 2343 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2344 attempt to substitute SMP alternatives once at boot.
2345
d0d4f69b
BH
2346 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2347 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2348 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2349 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2350 smsc-ircc2.ircc_irq= [HW] IRQ line
2351 smsc-ircc2.ircc_dma= [HW] DMA channel
2352 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2353 0: Toshiba Satellite 1800 (GP data pin select)
2354 1: Fast pin select (default)
2355 2: ATC IRMode
2356
1da177e4
LT
2357 snd-ad1816a= [HW,ALSA]
2358
2359 snd-ad1848= [HW,ALSA]
2360
2361 snd-ali5451= [HW,ALSA]
2362
2363 snd-als100= [HW,ALSA]
2364
2365 snd-als4000= [HW,ALSA]
2366
2367 snd-azt2320= [HW,ALSA]
2368
2369 snd-cmi8330= [HW,ALSA]
2370
2371 snd-cmipci= [HW,ALSA]
2372
2373 snd-cs4231= [HW,ALSA]
2374
2375 snd-cs4232= [HW,ALSA]
2376
2377 snd-cs4236= [HW,ALSA]
2378
2379 snd-cs4281= [HW,ALSA]
2380
2381 snd-cs46xx= [HW,ALSA]
2382
2383 snd-dt019x= [HW,ALSA]
2384
2385 snd-dummy= [HW,ALSA]
2386
2387 snd-emu10k1= [HW,ALSA]
2388
2389 snd-ens1370= [HW,ALSA]
2390
2391 snd-ens1371= [HW,ALSA]
2392
2393 snd-es968= [HW,ALSA]
2394
2395 snd-es1688= [HW,ALSA]
2396
2397 snd-es18xx= [HW,ALSA]
2398
2399 snd-es1938= [HW,ALSA]
2400
2401 snd-es1968= [HW,ALSA]
2402
2403 snd-fm801= [HW,ALSA]
2404
2405 snd-gusclassic= [HW,ALSA]
2406
2407 snd-gusextreme= [HW,ALSA]
2408
2409 snd-gusmax= [HW,ALSA]
2410
2411 snd-hdsp= [HW,ALSA]
2412
2413 snd-ice1712= [HW,ALSA]
2414
2415 snd-intel8x0= [HW,ALSA]
2416
2417 snd-interwave= [HW,ALSA]
2418
2419 snd-interwave-stb=
2420 [HW,ALSA]
2421
2422 snd-korg1212= [HW,ALSA]
2423
2424 snd-maestro3= [HW,ALSA]
2425
2426 snd-mpu401= [HW,ALSA]
2427
2428 snd-mtpav= [HW,ALSA]
2429
2430 snd-nm256= [HW,ALSA]
2431
2432 snd-opl3sa2= [HW,ALSA]
2433
2434 snd-opti92x-ad1848=
2435 [HW,ALSA]
2436
2437 snd-opti92x-cs4231=
2438 [HW,ALSA]
2439
2440 snd-opti93x= [HW,ALSA]
2441
2442 snd-pmac= [HW,ALSA]
2443
2444 snd-rme32= [HW,ALSA]
2445
2446 snd-rme96= [HW,ALSA]
2447
2448 snd-rme9652= [HW,ALSA]
2449
2450 snd-sb8= [HW,ALSA]
2451
2452 snd-sb16= [HW,ALSA]
2453
2454 snd-sbawe= [HW,ALSA]
2455
2456 snd-serial= [HW,ALSA]
2457
2458 snd-sgalaxy= [HW,ALSA]
2459
2460 snd-sonicvibes= [HW,ALSA]
2461
2462 snd-sun-amd7930=
2463 [HW,ALSA]
2464
2465 snd-sun-cs4231= [HW,ALSA]
2466
2467 snd-trident= [HW,ALSA]
2468
2469 snd-usb-audio= [HW,ALSA,USB]
2470
2471 snd-via82xx= [HW,ALSA]
2472
2473 snd-virmidi= [HW,ALSA]
2474
2475 snd-wavefront= [HW,ALSA]
2476
2477 snd-ymfpci= [HW,ALSA]
a9913044 2478
9c44bc03
IM
2479 softlockup_panic=
2480 [KNL] Should the soft-lockup detector generate panics.
2481
1da177e4
LT
2482 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2483 See Documentation/sonypi.txt
2484
2485 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2486 See Documentation/serial/specialix.txt.
1da177e4
LT
2487
2488 spia_io_base= [HW,MTD]
2489 spia_fio_base=
2490 spia_pedr=
2491 spia_peddr=
2492
2493 sscape= [HW,OSS]
2494 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2495
1da177e4
LT
2496 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2497 See Documentation/scsi/st.txt.
2498
f38f1d2a
SR
2499 stacktrace [FTRACE]
2500 Enabled the stack tracer on boot up.
2501
1da177e4
LT
2502 sti= [PARISC,HW]
2503 Format: <num>
2504 Set the STI (builtin display/keyboard on the HP-PARISC
2505 machines) console (graphic card) which should be used
2506 as the initial boot-console.
2507 See also comment in drivers/video/console/sticore.c.
2508
2509 sti_font= [HW]
2510 See comment in drivers/video/console/sticore.c.
2511
2512 stifb= [HW]
2513 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2514
cbf11071
TM
2515 sunrpc.min_resvport=
2516 sunrpc.max_resvport=
2517 [NFS,SUNRPC]
2518 SunRPC servers often require that client requests
2519 originate from a privileged port (i.e. a port in the
2520 range 0 < portnr < 1024).
2521 An administrator who wishes to reserve some of these
2522 ports for other uses may adjust the range that the
2523 kernel's sunrpc client considers to be privileged
2524 using these two parameters to set the minimum and
2525 maximum port values.
2526
42a7fc4a
GB
2527 sunrpc.pool_mode=
2528 [NFS]
2529 Control how the NFS server code allocates CPUs to
2530 service thread pools. Depending on how many NICs
2531 you have and where their interrupts are bound, this
2532 option will affect which CPUs will do NFS serving.
2533 Note: this parameter cannot be changed while the
2534 NFS server is running.
2535
2536 auto the server chooses an appropriate mode
2537 automatically using heuristics
2538 global a single global pool contains all CPUs
2539 percpu one pool for each CPU
2540 pernode one pool for each NUMA node (equivalent
2541 to global on non-NUMA machines)
2542
cbf11071
TM
2543 sunrpc.tcp_slot_table_entries=
2544 sunrpc.udp_slot_table_entries=
2545 [NFS,SUNRPC]
2546 Sets the upper limit on the number of simultaneous
2547 RPC calls that can be sent from the client to a
2548 server. Increasing these values may allow you to
2549 improve throughput, but will also increase the
2550 amount of memory reserved for use by the client.
2551
1da177e4 2552 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2553
1da177e4
LT
2554 switches= [HW,M68k]
2555
2556 sym53c416= [HW,SCSI]
2557 See header of drivers/scsi/sym53c416.c.
2558
5d6f647f
IM
2559 sysrq_always_enabled
2560 [KNL]
2561 Ignore sysrq setting - this boot parameter will
2562 neutralize any effect of /proc/sys/kernel/sysrq.
2563 Useful for debugging.
2564
1da177e4
LT
2565 t128= [HW,SCSI]
2566 See header of drivers/scsi/t128.c.
2567
2568 tdfx= [HW,DRM]
2569
77437fd4
DB
2570 test_suspend= [SUSPEND]
2571 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2572 standby suspend) as the system sleep state to briefly
2573 enter during system startup. The system is woken from
2574 this state using a wakeup-capable RTC alarm.
2575
1da177e4
LT
2576 thash_entries= [KNL,NET]
2577 Set number of hash buckets for TCP connection
2578
f8707ec9
LB
2579 thermal.act= [HW,ACPI]
2580 -1: disable all active trip points in all thermal zones
2581 <degrees C>: override all lowest active trip points
2582
c52a7419
LB
2583 thermal.crt= [HW,ACPI]
2584 -1: disable all critical trip points in all thermal zones
22a94d79 2585 <degrees C>: override all critical trip points
c52a7419 2586
f5487145
LB
2587 thermal.nocrt= [HW,ACPI]
2588 Set to disable actions on ACPI thermal zone
2589 critical and hot trip points.
2590
72b33ef8
LB
2591 thermal.off= [HW,ACPI]
2592 1: disable ACPI thermal control
2593
a70cdc52
LB
2594 thermal.psv= [HW,ACPI]
2595 -1: disable all passive trip points
ada9cfdd
RD
2596 <degrees C>: override all passive trip points to this
2597 value
a70cdc52 2598
730ff34d
LB
2599 thermal.tzp= [HW,ACPI]
2600 Specify global default ACPI thermal zone polling rate
2601 <deci-seconds>: poll all this frequency
2602 0: no polling (default)
2603
1da177e4
LT
2604 tmscsim= [HW,SCSI]
2605 See comment before function dc390_setup() in
2606 drivers/scsi/tmscsim.c.
2607
2b1a61f0
HC
2608 topology= [S390]
2609 Format: {off | on}
2610 Specify if the kernel should make use of the cpu
2611 topology informations if the hardware supports these.
2612 The scheduler will make use of these informations and
2613 e.g. base its process migration decisions on it.
2614 Default is off.
2615
1da177e4
LT
2616 tp720= [HW,PS2]
2617
9d612bef
LZ
2618 trace_buf_size=nn[KMG]
2619 [FTRACE] will set tracing buffer size.
631595fb 2620
020e5f85
LZ
2621 trace_event=[event-list]
2622 [FTRACE] Set and start specified trace events in order
2623 to facilitate early boot debugging.
2624 See also Documentation/trace/events.txt
2625
1da177e4 2626 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2627 Format:
2628 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2629
395628ef
AK
2630 tsc= Disable clocksource-must-verify flag for TSC.
2631 Format: <string>
2632 [x86] reliable: mark tsc clocksource as reliable, this
2633 disables clocksource verification at runtime.
2634 Used to enable high-resolution timer mode on older
2635 hardware, and in virtualized environment.
2636
a9913044
RD
2637 turbografx.map[2|3]= [HW,JOY]
2638 TurboGraFX parallel port interface
2639 Format:
2640 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2641 See also Documentation/input/joystick-parport.txt
2642
2643 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2644 See header of drivers/scsi/u14-34f.c.
2645
2646 uart401= [HW,OSS]
2647 Format: <io>,<irq>
2648
2649 uart6850= [HW,OSS]
2650 Format: <io>,<irq>
2651
f86dcc5a
ED
2652 uhash_entries= [KNL,NET]
2653 Set number of hash buckets for UDP/UDP-Lite connections
2654
5f8364b7
AS
2655 uhci-hcd.ignore_oc=
2656 [USB] Ignore overcurrent events (default N).
2657 Some badly-designed motherboards generate lots of
2658 bogus events, for ports that aren't wired to
2659 anything. Set this parameter to avoid log spamming.
2660 Note that genuine overcurrent events won't be
2661 reported either.
2662
e3a61b0a 2663 unknown_nmi_panic
6cececfc 2664 [X86]
e3a61b0a
SA
2665 Set unknown_nmi_panic=1 early on boot.
2666
b5e795f8
AS
2667 usbcore.autosuspend=
2668 [USB] The autosuspend time delay (in seconds) used
2669 for newly-detected USB devices (default 2). This
2670 is the time required before an idle device will be
2671 autosuspended. Devices for which the delay is set
eaafbc3a 2672 to a negative value won't be autosuspended at all.
b5e795f8 2673
fd7c519d
JK
2674 usbcore.usbfs_snoop=
2675 [USB] Set to log all usbfs traffic (default 0 = off).
2676
2677 usbcore.blinkenlights=
2678 [USB] Set to cycle leds on hubs (default 0 = off).
2679
2680 usbcore.old_scheme_first=
2681 [USB] Start with the old device initialization
2682 scheme (default 0 = off).
2683
2684 usbcore.use_both_schemes=
2685 [USB] Try the other device initialization scheme
2686 if the first one fails (default 1 = enabled).
2687
2688 usbcore.initial_descriptor_timeout=
2689 [USB] Specifies timeout for the initial 64-byte
2690 USB_REQ_GET_DESCRIPTOR request in milliseconds
2691 (default 5000 = 5.0 seconds).
2692
1da177e4
LT
2693 usbhid.mousepoll=
2694 [USBHID] The interval which mice are to be polled at.
a9913044 2695
d4f373e5
AS
2696 usb-storage.delay_use=
2697 [UMS] The delay in seconds before a new device is
2698 scanned for Logical Units (default 5).
2699
2700 usb-storage.quirks=
2701 [UMS] A list of quirks entries to supplement or
2702 override the built-in unusual_devs list. List
2703 entries are separated by commas. Each entry has
2704 the form VID:PID:Flags where VID and PID are Vendor
2705 and Product ID values (4-digit hex numbers) and
2706 Flags is a set of characters, each corresponding
2707 to a common usb-storage quirk flag as follows:
c838ea46
AS
2708 a = SANE_SENSE (collect more than 18 bytes
2709 of sense data);
a0bb1081
AS
2710 b = BAD_SENSE (don't collect more than 18
2711 bytes of sense data);
d4f373e5
AS
2712 c = FIX_CAPACITY (decrease the reported
2713 device capacity by one sector);
c838ea46
AS
2714 h = CAPACITY_HEURISTICS (decrease the
2715 reported device capacity by one
2716 sector if the number is odd);
d4f373e5
AS
2717 i = IGNORE_DEVICE (don't bind to this
2718 device);
2719 l = NOT_LOCKABLE (don't try to lock and
2720 unlock ejectable media);
2721 m = MAX_SECTORS_64 (don't transfer more
2722 than 64 sectors = 32 KB at a time);
c838ea46
AS
2723 o = CAPACITY_OK (accept the capacity
2724 reported by the device);
d4f373e5
AS
2725 r = IGNORE_RESIDUE (the device reports
2726 bogus residue values);
2727 s = SINGLE_LUN (the device has only one
2728 Logical Unit);
2729 w = NO_WP_DETECT (don't test whether the
2730 medium is write-protected).
2731 Example: quirks=0419:aaf5:rl,0421:0433:rc
2732
14315592
IC
2733 userpte=
2734 [X86] Flags controlling user PTE allocations.
2735
2736 nohigh = do not allocate PTE pages in
2737 HIGHMEM regardless of setting
2738 of CONFIG_HIGHPTE.
2739
6cececfc 2740 vdso= [X86,SH]
1dbf527c 2741 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2742 vdso=1: enable VDSO (default)
2743 vdso=0: disable VDSO mapping
2744
6cececfc 2745 vdso32= [X86]
af65d648
RM
2746 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2747 vdso32=1: enable 32-bit VDSO (default)
2748 vdso32=0: disable 32-bit VDSO mapping
2749
d080d397
YI
2750 vector= [IA-64,SMP]
2751 vector=percpu: enable percpu vector domain
2752
1da177e4
LT
2753 video= [FB] Frame buffer configuration
2754 See Documentation/fb/modedb.txt.
2755
cd4f0ef7 2756 vga= [BOOT,X86-32] Select a particular video mode
954a8b81 2757 See Documentation/x86/boot.txt and
a9913044 2758 Documentation/svga.txt.
1da177e4
LT
2759 Use vga=ask for menu.
2760 This is actually a boot loader parameter; the value is
2761 passed to the kernel using a special protocol.
2762
a9913044 2763 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2764 size of <nn>. This can be used to increase the
2765 minimum size (128MB on x86). It can also be used to
2766 decrease the size and leave more room for directly
2767 mapped kernel RAM.
2768
585c3047
PO
2769 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2770 Format: <command>
1da177e4 2771
585c3047
PO
2772 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2773 Format: <command>
2774
2775 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2776 Format: <command>
a9913044 2777
9ea9a886
CL
2778 vt.cur_default= [VT] Default cursor shape.
2779 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2780 the parameters of the <Esc>[?A;B;Cc escape sequence;
2781 see VGA-softcursor.txt. Default: 2 = underline.
2782
0cb55ad2
RD
2783 vt.default_blu= [VT]
2784 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2785 Change the default blue palette of the console.
2786 This is a 16-member array composed of values
2787 ranging from 0-255.
2788
2789 vt.default_grn= [VT]
2790 Format: <green0>,<green1>,<green2>,...,<green15>
2791 Change the default green palette of the console.
2792 This is a 16-member array composed of values
2793 ranging from 0-255.
2794
2795 vt.default_red= [VT]
2796 Format: <red0>,<red1>,<red2>,...,<red15>
2797 Change the default red palette of the console.
2798 This is a 16-member array composed of values
2799 ranging from 0-255.
2800
2801 vt.default_utf8=
2802 [VT]
2803 Format=<0|1>
2804 Set system-wide default UTF-8 mode for all tty's.
2805 Default is 1, i.e. UTF-8 mode is enabled for all
2806 newly opened terminals.
2807
f6c06b68
MG
2808 vt.global_cursor_default=
2809 [VT]
2810 Format=<-1|0|1>
2811 Set system-wide default for whether a cursor
2812 is shown on new VTs. Default is -1,
2813 i.e. cursors will be created by default unless
2814 overridden by individual drivers. 0 will hide
2815 cursors, 1 will display them.
2816
1da177e4
LT
2817 waveartist= [HW,OSS]
2818 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2819
1da177e4
LT
2820 wd33c93= [HW,SCSI]
2821 See header of drivers/scsi/wd33c93.c.
2822
2823 wd7000= [HW,SCSI]
2824 See header of drivers/scsi/wd7000.c.
2825
2826 wdt= [WDT] Watchdog
8dfe9c21 2827 See Documentation/watchdog/wdt.txt.
1da177e4 2828
0cb55ad2
RD
2829 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2830 default x2apic cluster mode on platforms
2831 supporting x2apic.
2832
bb24c471
JP
2833 x86_mrst_timer= [X86-32,APBT]
2834 Choose timer option for x86 Moorestown MID platform.
2835 Two valid options are apbt timer only and lapic timer
2836 plus one apbt timer for broadcast timer.
2837 x86_mrst_timer=apbt_only | lapic_and_apbt
2838
1da177e4
LT
2839 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2840 xd_geo= See header of drivers/block/xd.c.
2841
2842 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2843 Format:
2844 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2845
a9913044 2846______________________________________________________________________
1da177e4
LT
2847
2848TODO:
2849
2850 Add documentation for ALSA options.
2851 Add more DRM drivers.