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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.
84c08fd6 61 KGDB Kernel debugger support is enabled.
fef07aae 62 KVM Kernel Virtual Machine support is enabled.
11ef697b 63 LIBATA Libata driver is enabled
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64 LP Printer support is enabled.
65 LOOP Loopback device support is enabled.
66 M68k M68k architecture is enabled.
67 These options have more detailed description inside of
68 Documentation/m68k/kernel-options.txt.
69 MCA MCA bus support is enabled.
70 MDA MDA console support is enabled.
71 MOUSE Appropriate mouse support is enabled.
309e57df 72 MSI Message Signaled Interrupts (PCI).
c8facbb6 73 MTD MTD (Memory Technology Device) support is enabled.
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74 NET Appropriate network support is enabled.
75 NUMA NUMA support is enabled.
734efb46 76 GENERIC_TIME The generic timeofday code is enabled.
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77 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
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79 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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81 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
7f785763 83 PCIE PCI Express support is enabled.
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84 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
92 A lot of drivers has their options described inside of
93 Documentation/scsi/.
20510f2f 94 SECURITY Different security models are enabled.
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95 SELINUX SELinux support is enabled.
96 SERIAL Serial support is enabled.
e523d93c 97 SH SuperH architecture is enabled.
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98 SMP The kernel is an SMP kernel.
99 SPARC Sparc architecture is enabled.
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100 SWSUSP Software suspend (hibernation) is enabled.
101 SUSPEND System suspend states are enabled.
f38f1d2a 102 FTRACE Function tracing enabled.
225a9be2 103 TPM TPM drivers are enabled.
1da177e4 104 TS Appropriate touchscreen support is enabled.
d4f373e5 105 UMS USB Mass Storage support is enabled.
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106 USB USB support is enabled.
107 USBHID USB Human Interface Device support is enabled.
108 V4L Video For Linux support is enabled.
109 VGA The VGA console has been enabled.
110 VT Virtual terminal support is enabled.
111 WDT Watchdog support is enabled.
112 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 113 X86-32 X86-32, aka i386 architecture is enabled.
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114 X86-64 X86-64 architecture is enabled.
115 More X86-64 boot options can be found in
71cced6e 116 Documentation/x86/x86_64/boot-options.txt .
c0115606 117 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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118
119In addition, the following text indicates that the option:
120
121 BUGS= Relates to possible processor bugs on the said processor.
122 KNL Is a kernel start-up parameter.
123 BOOT Is a boot loader parameter.
124
125Parameters denoted with BOOT are actually interpreted by the boot
126loader, and have no meaning to the kernel directly.
127Do not modify the syntax of boot loader parameters without extreme
954a8b81 128need or coordination with <Documentation/x86/boot.txt>.
1da177e4 129
5558870b 130There are also arch-specific kernel-parameters not documented here.
71cced6e 131See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 132
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133Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
134a trailing = on the name of any parameter states that that parameter will
135be entered as an environment variable, whereas its absence indicates that
136it will appear as a kernel argument readable via /proc/cmdline by programs
137running once the system is up.
138
9c4751fd 139The number of kernel parameters is not limited, but the length of the
140complete command line (parameters including spaces etc.) is limited to
141a fixed number of characters. This limit depends on the architecture
142and is between 256 and 4096 characters. It is defined in the file
143./include/asm/setup.h as COMMAND_LINE_SIZE.
144
145
6cececfc 146 acpi= [HW,ACPI,X86]
03d926f8 147 Advanced Configuration and Power Interface
68ca4069 148 Format: { force | off | strict | noirq | rsdt }
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149 force -- enable ACPI if default was off
150 off -- disable ACPI if default was on
151 noirq -- do not use ACPI for IRQ routing
a9913044 152 strict -- Be less tolerant of platforms that are not
1da177e4 153 strictly ACPI specification compliant.
237889bf 154 rsdt -- prefer RSDT over (default) XSDT
aa2110cb 155 copy_dsdt -- copy DSDT to memory
1da177e4 156
53471121 157 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 158
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159 acpi_apic_instance= [ACPI, IOAPIC]
160 Format: <int>
161 2: use 2nd APIC table, if available
162 1,0: use 1st APIC table
4e381a4f 163 default: 0
a1fdcc0d 164
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165 acpi_backlight= [HW,ACPI]
166 acpi_backlight=vendor
167 acpi_backlight=video
168 If set to vendor, prefer vendor specific driver
169 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
170 of the ACPI video.ko driver.
171
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172 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
173 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 174 Format: <int>
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175 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
176 debug output. Bits in debug_layer correspond to a
177 _COMPONENT in an ACPI source file, e.g.,
178 #define _COMPONENT ACPI_PCI_COMPONENT
179 Bits in debug_level correspond to a level in
180 ACPI_DEBUG_PRINT statements, e.g.,
181 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
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182 The debug_level mask defaults to "info". See
183 Documentation/acpi/debug.txt for more information about
184 debug layers and levels.
a0d84a92 185
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186 Enable processor driver info messages:
187 acpi.debug_layer=0x20000000
188 Enable PCI/PCI interrupt routing info messages:
189 acpi.debug_layer=0x400000
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190 Enable AML "Debug" output, i.e., stores to the Debug
191 object while interpreting AML:
192 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
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193 Enable all messages related to ACPI hardware:
194 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
195
196 Some values produce so much output that the system is
197 unusable. The "log_buf_len" parameter may be useful
198 if you need to capture more output.
f989106c 199
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200 acpi_display_output= [HW,ACPI]
201 acpi_display_output=vendor
202 acpi_display_output=video
203 See above.
204
205 acpi_irq_balance [HW,ACPI]
206 ACPI will balance active IRQs
207 default in APIC mode
208
209 acpi_irq_nobalance [HW,ACPI]
210 ACPI will not move active IRQs (default)
211 default in PIC mode
212
213 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
214 Format: <irq>,<irq>...
215
216 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
217 use by PCI
218 Format: <irq>,<irq>...
219
220 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
221
222 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
223 Format: To spoof as Windows 98: ="Microsoft Windows"
224
225 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
226 acpi_osi="string1" # add string1 -- only one string
227 acpi_osi="!string2" # remove built-in string2
228 acpi_osi= # disable all strings
229
6cececfc 230 acpi_pm_good [X86]
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231 Override the pmtimer bug detection: force the kernel
232 to assume that this machine's pmtimer latches its value
233 and always returns good values.
234
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235 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
236 Format: { level | edge | high | low }
237
238 acpi_serialize [HW,ACPI] force serialization of AML methods
239
240 acpi_skip_timer_override [HW,ACPI]
241 Recognize and ignore IRQ0/pin2 Interrupt Override.
242 For broken nForce2 BIOS resulting in XT-PIC timer.
243
244 acpi_sleep= [HW,ACPI] Sleep options
245 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
d7f0eea9 246 old_ordering, s4_nonvs, sci_force_enable }
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247 See Documentation/power/video.txt for information on
248 s3_bios and s3_mode.
249 s3_beep is for debugging; it makes the PC's speaker beep
250 as soon as the kernel's real-mode entry point is called.
251 s4_nohwsig prevents ACPI hardware signature from being
252 used during resume from hibernation.
253 old_ordering causes the ACPI 1.0 ordering of the _PTS
254 control method, with respect to putting devices into
255 low power states, to be enforced (the ACPI 2.0 ordering
256 of _PTS is used by default).
257 s4_nonvs prevents the kernel from saving/restoring the
258 ACPI NVS memory during hibernation.
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259 sci_force_enable causes the kernel to set SCI_EN directly
260 on resume from S1/S3 (which is against the ACPI spec,
261 but some broken systems don't work without it).
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262
263 acpi_use_timer_override [HW,ACPI]
264 Use timer override. For some broken Nvidia NF5 boards
265 that require a timer override, but don't have HPET
266
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267 acpi_enforce_resources= [ACPI]
268 { strict | lax | no }
269 Check for resource conflicts between native drivers
270 and ACPI OperationRegions (SystemIO and SystemMemory
271 only). IO ports and memory declared in ACPI might be
272 used by the ACPI subsystem in arbitrary AML code and
273 can interfere with legacy drivers.
274 strict (default): access to resources claimed by ACPI
275 is denied; legacy drivers trying to access reserved
276 resources will fail to bind to device using them.
277 lax: access to resources claimed by ACPI is allowed;
278 legacy drivers trying to access reserved resources
279 will bind successfully but a warning message is logged.
280 no: ACPI OperationRegions are not marked as reserved,
281 no further checks are performed.
282
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283 ad1848= [HW,OSS]
284 Format: <io>,<irq>,<dma>,<dma2>,<type>
285
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286 add_efi_memmap [EFI; X86] Include EFI memory map in
287 kernel's map of available physical RAM.
288
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289 advansys= [HW,SCSI]
290 See header of drivers/scsi/advansys.c.
291
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292 aedsp16= [HW,OSS] Audio Excel DSP 16
293 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
294 See also header of sound/oss/aedsp16.c.
a9913044 295
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296 agp= [AGP]
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
301
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302 aha152x= [HW,SCSI]
303 See Documentation/scsi/aha152x.txt.
304
305 aha1542= [HW,SCSI]
306 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
307
308 aic7xxx= [HW,SCSI]
309 See Documentation/scsi/aic7xxx.txt.
310
311 aic79xx= [HW,SCSI]
312 See Documentation/scsi/aic79xx.txt.
313
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314 alignment= [KNL,ARM]
315 Allow the default userspace alignment fault handler
316 behaviour to be specified. Bit 0 enables warnings,
317 bit 1 enables fixups, and bit 2 sends a segfault.
318
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319 amd_iommu= [HW,X86-84]
320 Pass parameters to the AMD IOMMU driver in the system.
321 Possible values are:
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322 fullflush - enable flushing of IO/TLB entries when
323 they are unmapped. Otherwise they are
324 flushed before they will be reused, which
325 is a lot of faster
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326 off - do not initialize any AMD IOMMU found in
327 the system
afa9fdc2 328
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329 amijoy.map= [HW,JOY] Amiga joystick support
330 Map of devices attached to JOY0DAT and JOY1DAT
331 Format: <a>,<b>
332 See also Documentation/kernel/input/joystick.txt
333
334 analog.map= [HW,JOY] Analog joystick and gamepad support
335 Specifies type or capabilities of an analog joystick
336 connected to one of 16 gameports
337 Format: <type1>,<type2>,..<type16>
338
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339 apc= [HW,SPARC]
340 Power management functions (SPARCstation-4/5 + deriv.)
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341 Format: noidle
342 Disable APC CPU standby support. SPARCstation-Fox does
343 not play well with APC CPU idle - disable it if you have
344 APC and your system crashes randomly.
345
ca1eda2d 346 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
c8facbb6 347 Change the output verbosity whilst booting
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348 Format: { quiet (default) | verbose | debug }
349 Change the amount of debugging information output
350 when initialising the APIC and IO-APIC components.
a9913044 351
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352 autoconf= [IPV6]
353 See Documentation/networking/ipv6.txt.
354
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355 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
356 Limit apic dumping. The parameter defines the maximal
357 number of local apics being dumped. Also it is possible
358 to set it to "all" by meaning -- no limit here.
359 Format: { 1 (default) | 2 | ... | all }.
360 The parameter valid if only apic=debug or
361 apic=verbose is specified.
362 Example: apic=debug show_lapic=all
363
1da177e4 364 apm= [APM] Advanced Power Management
71f77055 365 See header of arch/x86/kernel/apm_32.c.
1da177e4 366
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367 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
368 Format: <io>,<irq>,<nodeID>
369
370 ataflop= [HW,M68k]
371
372 atarimouse= [HW,MOUSE] Atari Mouse
373
374 atascsi= [HW,SCSI] Atari SCSI
375
376 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
377 EzKey and similar keyboards
378
379 atkbd.reset= [HW] Reset keyboard during initialization
380
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381 atkbd.set= [HW] Select keyboard code set
382 Format: <int> (2 = AT (default), 3 = PS/2)
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383
384 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
385 keyboards
386
387 atkbd.softraw= [HW] Choose between synthetic and real raw mode
388 Format: <bool> (0 = real, 1 = synthetic (default))
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389
390 atkbd.softrepeat= [HW]
391 Use software keyboard repeat
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392
393 autotest [IA64]
394
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395 baycom_epp= [HW,AX25]
396 Format: <io>,<mode>
a9913044 397
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398 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
399 Format: <io>,<mode>
400 See header of drivers/net/hamradio/baycom_par.c.
401
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402 baycom_ser_fdx= [HW,AX25]
403 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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404 Format: <io>,<irq>,<mode>[,<baud>]
405 See header of drivers/net/hamradio/baycom_ser_fdx.c.
406
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407 baycom_ser_hdx= [HW,AX25]
408 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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409 Format: <io>,<irq>,<mode>
410 See header of drivers/net/hamradio/baycom_ser_hdx.c.
411
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412 boot_delay= Milliseconds to delay each printk during boot.
413 Values larger than 10 seconds (10000) are changed to
414 no delay (0).
415 Format: integer
416
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417 bootmem_debug [KNL] Enable bootmem allocator debug messages.
418
1da177e4 419 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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420 bttv.radio= Most important insmod options are available as
421 kernel args too.
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422 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
423 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
424
425 BusLogic= [HW,SCSI]
426 See drivers/scsi/BusLogic.c, comment before function
427 BusLogic_ParseDriverOptions().
428
429 c101= [NET] Moxa C101 synchronous serial card
430
cd4f0ef7 431 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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432 Sometimes CPU hardware bugs make them report the cache
433 size incorrectly. The kernel will attempt work arounds
434 to fix known problems, but for some CPUs it is not
435 possible to determine what the correct size should be.
436 This option provides an override for these situations.
437
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438 capability.disable=
439 [SECURITY] Disable capabilities. This would normally
440 be used only if an alternative security model is to be
441 configured. Potentially dangerous and should only be
442 used if you are entirely sure of the consequences.
443
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444 ccw_timeout_log [S390]
445 See Documentation/s390/CommonIO for details.
1da177e4 446
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447 cgroup_disable= [KNL] Disable a particular controller
448 Format: {name of the controller(s) to disable}
449 {Currently supported controllers - "memory"}
450
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451 checkreqprot [SELINUX] Set initial checkreqprot flag value.
452 Format: { "0" | "1" }
453 See security/selinux/Kconfig help text.
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454 0 -- check protection applied by kernel (includes
455 any implied execute protection).
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456 1 -- check protection requested by application.
457 Default value is set via a kernel config option.
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458 Value can be changed at runtime via
459 /selinux/checkreqprot.
460
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461 cio_ignore= [S390]
462 See Documentation/s390/CommonIO for details.
463
cd4f0ef7 464 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 465 [Deprecated]
3f6dee9b 466 Forces specified clocksource (if available) to be used
734efb46 467 when calculating gettimeofday(). If specified
3f6dee9b 468 clocksource is not available, it defaults to PIT.
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469 Format: { pit | tsc | cyclone | pmtmr }
470
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471 clocksource= [GENERIC_TIME] Override the default clocksource
472 Format: <string>
473 Override the default clocksource and use the clocksource
474 with the name specified.
475 Some clocksource names to choose from, depending on
476 the platform:
477 [all] jiffies (this is the base, fallback clocksource)
478 [ACPI] acpi_pm
479 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
480 pxa_timer,timer3,32k_counter,timer0_1
481 [AVR32] avr32
cd4f0ef7 482 [X86-32] pit,hpet,tsc,vmi-timer;
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483 scx200_hrt on Geode; cyclone on IBM x440
484 [MIPS] MIPS
485 [PARISC] cr16
486 [S390] tod
487 [SH] SuperH
488 [SPARC64] tick
489 [X86-64] hpet,tsc
490
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491 clearcpuid=BITNUM [X86]
492 Disable CPUID feature X for the kernel. See
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493 arch/x86/include/asm/cpufeature.h for the valid bit
494 numbers. Note the Linux specific bits are not necessarily
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495 stable over kernel options, but the vendor specific
496 ones should be.
497 Also note that user programs calling CPUID directly
498 or using the feature without checking anything
499 will still see it. This just prevents it from
500 being used by the kernel or shown in /proc/cpuinfo.
501 Also note the kernel might malfunction if you disable
502 some critical bits.
503
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504 cmo_free_hint= [PPC] Format: { yes | no }
505 Specify whether pages are marked as being inactive
506 when they are freed. This is used in CMO environments
507 to determine OS memory pressure for page stealing by
508 a hypervisor.
509 Default: yes
510
6cececfc 511 code_bytes [X86] How many bytes of object code to print
a25bd949 512 in an oops report.
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513 Range: 0 - 8192
514 Default: 64
515
1da177e4 516 com20020= [HW,NET] ARCnet - COM20020 chipset
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517 Format:
518 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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519
520 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
521 Format: <io>[,<irq>]
522
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523 com90xx= [HW,NET]
524 ARCnet - COM90xx chipset (memory-mapped buffers)
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525 Format: <io>[,<irq>[,<memstart>]]
526
527 condev= [HW,S390] console device
528 conmode=
a9913044 529
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530 console= [KNL] Output console device and options.
531
532 tty<n> Use the virtual console device <n>.
533
534 ttyS<n>[,options]
f1a1c2dc 535 ttyUSB0[,options]
1da177e4 536 Use the specified serial port. The options are of
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RD
537 the form "bbbbpnf", where "bbbb" is the baud rate,
538 "p" is parity ("n", "o", or "e"), "n" is number of
539 bits, and "f" is flow control ("r" for RTS or
540 omit it). Default is "9600n8".
541
542 See Documentation/serial-console.txt for more
543 information. See
544 Documentation/networking/netconsole.txt for an
545 alternative.
1da177e4 546
18a8bd94
YL
547 uart[8250],io,<addr>[,options]
548 uart[8250],mmio,<addr>[,options]
1da177e4
LT
549 Start an early, polled-mode console on the 8250/16550
550 UART at the specified I/O port or MMIO address,
551 switching to the matching ttyS device later. The
552 options are the same as for ttyS, above.
553
f7511d5f
ST
554 If the device connected to the port is not a TTY but a braille
555 device, prepend "brl," before the device type, for instance
556 console=brl,ttyS0
557 For now, only VisioBraille is supported.
558
f324edc8
DM
559 consoleblank= [KNL] The console blank (screen saver) timeout in
560 seconds. Defaults to 10*60 = 10mins. A value of 0
561 disables the blank timer.
562
4cb0e11b
HK
563 coredump_filter=
564 [KNL] Change the default value for
565 /proc/<pid>/coredump_filter.
566 See also Documentation/filesystems/proc.txt.
567
1da177e4 568 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
569 Format:
570 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 571
dc009d92
EB
572 crashkernel=nn[KMG]@ss[KMG]
573 [KNL] Reserve a chunk of physical memory to
574 hold a kernel to switch to with kexec on panic.
575
fb391599
BW
576 crashkernel=range1:size1[,range2:size2,...][@offset]
577 [KNL] Same as above, but depends on the memory
578 in the running system. The syntax of range is
579 start-[end] where start and end are both
580 a memory unit (amount[KMG]). See also
581 Documentation/kdump/kdump.txt for a example.
582
1da177e4
LT
583 cs89x0_dma= [HW,NET]
584 Format: <dma>
585
586 cs89x0_media= [HW,NET]
587 Format: { rj45 | aui | bnc }
a9913044 588
a9913044 589 dasd= [HW,NET]
1da177e4
LT
590 See header of drivers/s390/block/dasd_devmap.c.
591
592 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
593 (one device per port)
594 Format: <port#>,<type>
595 See also Documentation/input/joystick-parport.txt
596
597 debug [KNL] Enable kernel debugging (events log level).
598
cae2ed9a
IM
599 debug_locks_verbose=
600 [KNL] verbose self-tests
601 Format=<0|1>
602 Print debugging info while doing the locking API
603 self-tests.
604 We default to 0 (no extra messages), setting it to
605 1 will print _a lot_ more information - normally
606 only useful to kernel developers.
607
3ac7fe5a
TG
608 debug_objects [KNL] Enable object debugging
609
3e8ebb5c
KM
610 no_debug_objects
611 [KNL] Disable object debugging
612
d3af01f1
TG
613 debugpat [X86] Enable PAT debugging
614
2d27a966 615 decnet.addr= [HW,NET]
1da177e4
LT
616 Format: <area>[,<node>]
617 See also Documentation/networking/decnet.txt.
618
0cb55ad2
RD
619 default_hugepagesz=
620 [same as hugepagesz=] The size of the default
621 HugeTLB page size. This is the size represented by
622 the legacy /proc/ hugepages APIs, used for SHM, and
623 default size when mounting hugetlbfs filesystems.
624 Defaults to the default architecture's huge page size
625 if not specified.
55ff9780 626
1da177e4
LT
627 dhash_entries= [KNL]
628 Set number of hash buckets for dentry cache.
a9913044 629
1da177e4
LT
630 digi= [HW,SERIAL]
631 IO parameters + enable/disable command.
632
633 digiepca= [HW,SERIAL]
634 See drivers/char/README.epca and
31c00fc1 635 Documentation/serial/digiepca.txt.
1da177e4 636
b0f83b28
BH
637 disable= [IPV6]
638 See Documentation/networking/ipv6.txt.
639
640 disable_ipv6= [IPV6]
641 See Documentation/networking/ipv6.txt.
642
95ffa243 643 disable_mtrr_cleanup [X86]
95ffa243
YL
644 The kernel tries to adjust MTRR layout from continuous
645 to discrete, to make X server driver able to add WB
0cb55ad2 646 entry later. This parameter disables that.
95ffa243 647
093af8d7 648 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
649 By default the kernel will trim any uncacheable
650 memory out of your available memory pool based on
651 MTRR settings. This parameter disables that behavior,
652 possibly causing your machine to run very slowly.
653
6cececfc 654 disable_timer_pin_1 [X86]
0cb55ad2
RD
655 Disable PIN 1 of APIC timer
656 Can be useful to work around chipset bugs.
657
1da177e4
LT
658 dmasound= [HW,OSS] Sound subsystem buffers
659
0cb55ad2
RD
660 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
661 this option disables the debugging code at boot.
662
663 dma_debug_entries=<number>
664 This option allows to tune the number of preallocated
665 entries for DMA-API debugging code. One entry is
666 required per DMA-API allocation. Use this if the
667 DMA-API debugging code disables itself because the
668 architectural default is too low.
669
1745de5e
JR
670 dma_debug_driver=<driver_name>
671 With this option the DMA-API debugging driver
672 filter feature can be enabled at boot time. Just
673 pass the driver to filter for as the parameter.
674 The filter can be disabled or changed to another
675 driver later using sysfs.
676
1da177e4
LT
677 dscc4.setup= [NET]
678
679 dtc3181e= [HW,SCSI]
680
0cb55ad2
RD
681 dynamic_printk Enables pr_debug()/dev_dbg() calls if
682 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
683 These can also be switched on/off via
684 <debugfs>/dynamic_printk/modules
685
686 earlycon= [KNL] Output early console device and options.
687 uart[8250],io,<addr>[,options]
688 uart[8250],mmio,<addr>[,options]
689 Start an early, polled-mode console on the 8250/16550
690 UART at the specified I/O port or MMIO address.
691 The options are the same as for ttyS, above.
692
6cececfc 693 earlyprintk= [X86,SH,BLACKFIN]
1da177e4
LT
694 earlyprintk=vga
695 earlyprintk=serial[,ttySn[,baudrate]]
ea3acb19 696 earlyprintk=ttySn[,baudrate]
9780bc41 697 earlyprintk=dbgp[debugController#]
1da177e4 698
a9913044 699 Append ",keep" to not disable it when the real console
1da177e4
LT
700 takes over.
701
5c05917e 702 Only vga or serial or usb debug port at a time.
1da177e4
LT
703
704 Currently only ttyS0 and ttyS1 are supported.
705
706 Interaction with the standard serial driver is not
707 very good.
708
709 The VGA output is eventually overwritten by the real
710 console.
711
9731191f
JW
712 ekgdboc= [X86,KGDB] Allow early kernel console debugging
713 ekgdboc=kbd
714
715 This is desgined to be used in conjunction with
716 the boot argument: earlyprintk=vga
717
1da177e4
LT
718 eata= [HW,SCSI]
719
1da177e4 720 edd= [EDD]
8c4dd606 721 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 722
1da177e4
LT
723 eisa_irq_edge= [PARISC,HW]
724 See header of drivers/parisc/eisa.c.
725
cd4f0ef7 726 elanfreq= [X86-32]
1da177e4 727 See comment before function elanfreq_setup() in
71f77055 728 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
729
730 elevator= [IOSCHED]
16ab3adf 731 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
732 See Documentation/block/as-iosched.txt and
733 Documentation/block/deadline-iosched.txt for details.
734
6cececfc 735 elfcorehdr= [IA64,PPC,SH,X86]
a9913044 736 Specifies physical address of start of kernel core
aac04b32
VG
737 image elf header. Generally kexec loader will
738 pass this option to capture kernel.
739 See Documentation/kdump/kdump.txt for details.
1da177e4 740
0cb55ad2
RD
741 enable_mtrr_cleanup [X86]
742 The kernel tries to adjust MTRR layout from continuous
743 to discrete, to make X server driver able to add WB
744 entry later. This parameter enables that.
745
ca1eda2d 746 enable_timer_pin_1 [X86]
0cb55ad2
RD
747 Enable PIN 1 of APIC timer
748 Can be useful to work around chipset bugs
749 (in particular on some ATI chipsets).
750 The kernel tries to set a reasonable default.
751
1da177e4
LT
752 enforcing [SELINUX] Set initial enforcing status.
753 Format: {"0" | "1"}
754 See security/selinux/Kconfig help text.
755 0 -- permissive (log only, no denials).
756 1 -- enforcing (deny and log).
757 Default value is 0.
758 Value can be changed at runtime via /selinux/enforce.
759
a08f82d0
HY
760 erst_disable [ACPI]
761 Disable Error Record Serialization Table (ERST)
762 support.
763
1da177e4
LT
764 ether= [HW,NET] Ethernet cards parameters
765 This option is obsoleted by the "netdev=" option, which
766 has equivalent usage. See its documentation for details.
767
de1ba09b
AM
768 failslab=
769 fail_page_alloc=
770 fail_make_request=[KNL]
771 General fault injection mechanism.
772 Format: <interval>,<probability>,<space>,<times>
773 See also /Documentation/fault-injection/.
774
1da177e4
LT
775 fd_mcs= [HW,SCSI]
776 See header of drivers/scsi/fd_mcs.c.
777
778 fdomain= [HW,SCSI]
779 See header of drivers/scsi/fdomain.c.
780
781 floppy= [HW]
31c00fc1 782 See Documentation/blockdev/floppy.txt.
1da177e4 783
f13ae30e
AC
784 force_pal_cache_flush
785 [IA-64] Avoid check_sal_cache_flush which may hang on
786 buggy SAL_CACHE_FLUSH implementations. Using this
787 parameter will force ia64_sal_cache_flush to call
788 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
789
d9e54076 790 ftrace=[tracer]
2af15d6a 791 [FTRACE] will set and start the specified tracer
d9e54076
PZ
792 as early as possible in order to facilitate early
793 boot debugging.
794
cecbca96 795 ftrace_dump_on_oops[=orig_cpu]
2af15d6a 796 [FTRACE] will dump the trace buffers on oops.
cecbca96
FW
797 If no parameter is passed, ftrace will dump
798 buffers of all CPUs, but if you pass orig_cpu, it will
799 dump only the buffer of the CPU that triggered the
800 oops.
2af15d6a
SR
801
802 ftrace_filter=[function-list]
803 [FTRACE] Limit the functions traced by the function
804 tracer at boot up. function-list is a comma separated
805 list of functions. This list can be changed at run
806 time by the set_ftrace_filter file in the debugfs
807 tracing directory.
808
809 ftrace_notrace=[function-list]
810 [FTRACE] Do not trace the functions specified in
811 function-list. This list can be changed at run time
812 by the set_ftrace_notrace file in the debugfs
813 tracing directory.
d9e54076 814
369bc18f
SA
815 ftrace_graph_filter=[function-list]
816 [FTRACE] Limit the top level callers functions traced
817 by the function graph tracer at boot up.
818 function-list is a comma separated list of functions
819 that can be changed at run time by the
820 set_graph_function file in the debugfs tracing directory.
821
1da177e4
LT
822 gamecon.map[2|3]=
823 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
824 support via parallel port (up to 5 devices per port)
825 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
826 See also Documentation/input/joystick-parport.txt
827
828 gamma= [HW,DRM]
829
aaf23042
YL
830 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
831 Format: off | on
832 default: on
833
2521f2c2
PO
834 gcov_persist= [GCOV] When non-zero (default), profiling data for
835 kernel modules is saved and remains accessible via
836 debugfs, even when the module is unloaded/reloaded.
837 When zero, profiling data is discarded and associated
838 debugfs files are removed at module unload time.
839
1da177e4
LT
840 gdth= [HW,SCSI]
841 See header of drivers/scsi/gdth.c.
842
843 gpt [EFI] Forces disk with valid GPT signature but
844 invalid Protective MBR to be treated as GPT.
845
1da177e4
LT
846 gvp11= [HW,SCSI]
847
848 hashdist= [KNL,NUMA] Large hashes allocated during boot
849 are distributed across NUMA nodes. Defaults on
429aa0fc 850 for 64bit NUMA, off otherwise.
a9913044 851 Format: 0 | 1 (for off | on)
1da177e4
LT
852
853 hcl= [IA-64] SGI's Hardware Graph compatibility layer
854
855 hd= [EIDE] (E)IDE hard drive subsystem geometry
856 Format: <cyl>,<head>,<sect>
857
ea8c071c
HY
858 hest_disable [ACPI]
859 Disable Hardware Error Source Table (HEST) support;
860 corresponding firmware-first mode error processing
861 logic will be disabled.
862
1da177e4
LT
863 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
864 size of <nn>. This works even on boxes that have no
865 highmem otherwise. This also works to reduce highmem
866 size on bigger boxes.
867
54cdfdb4
TG
868 highres= [KNL] Enable/disable high resolution timer mode.
869 Valid parameters: "on", "off"
870 Default: "on"
871
1da177e4
LT
872 hisax= [HW,ISDN]
873 See Documentation/isdn/README.HiSax.
874
0cb55ad2
RD
875 hlt [BUGS=ARM,SH]
876
877 hpet= [X86-32,HPET] option to control HPET usage
878 Format: { enable (default) | disable | force |
879 verbose }
880 disable: disable HPET and use PIT instead
881 force: allow force enabled of undocumented chips (ICH4,
882 VIA, nVidia)
883 verbose: show contents of HPET registers during setup
884
b4718e62
AK
885 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
886 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
887 On x86-64 and powerpc, this option can be specified
888 multiple times interleaved with hugepages= to reserve
889 huge pages of different sizes. Valid pages sizes on
890 x86-64 are 2M (when the CPU supports "pse") and 1G
891 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
892 Note that 1GB pages can only be allocated at boot time
893 using hugepages= and not freed afterwards.
6902aa84 894
555d61d6
HB
895 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
896 terminal devices. Valid values: 0..8
431429ff
HB
897 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
898 If specified, z/VM IUCV HVC accepts connections
899 from listed z/VM user IDs only.
cef7125d 900
3a853fb9 901 i2c_bus= [HW] Override the default board specific I2C bus speed
7954763b
JN
902 or register an additional I2C bus that is not
903 registered from board initialization code.
3a853fb9
JN
904 Format:
905 <bus_id>,<clkrate>
906
36d95739 907 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 908 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
909 i8042.dumbkbd [HW] Pretend that controller can only read data from
910 keyboard and cannot control its state
1da177e4
LT
911 (Don't attempt to blink the leds)
912 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 913 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
914 i8042.noloop [HW] Disable the AUX Loopback command while probing
915 for the AUX port
1da177e4
LT
916 i8042.nomux [HW] Don't check presence of an active multiplexing
917 controller
918 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
919 controllers
920 i8042.panicblink=
921 [HW] Frequency with which keyboard LEDs should blink
922 when kernel panics (default is 0.5 sec)
923 i8042.reset [HW] Reset the controller during init and cleanup
924 i8042.unlock [HW] Unlock (ignore) the keylock
925
926 i810= [HW,DRM]
927
e70c9d5e
DT
928 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
929 indicates that the driver is running on unsupported
930 hardware.
1da177e4
LT
931 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
932 does not match list of supported models.
933 i8k.power_status
934 [HW] Report power status in /proc/i8k
935 (disabled by default)
936 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
937 capability is set.
938
939 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
940 See Documentation/mca.txt.
941
942 icn= [HW,ISDN]
943 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
944
0af80c04
DF
945 ide-core.nodma= [HW] (E)IDE subsystem
946 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
075affcb
BZ
947 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
948 .cdrom .chs .ignore_cable are additional options
1c10e938 949 See Documentation/ide/ide.txt.
1da177e4 950
0cb55ad2
RD
951 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
952 Claim all unknown PCI IDE storage controllers.
953
f039b754 954 idle= [X86]
ada9cfdd
RD
955 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
956 Poll forces a polling idle loop that can slightly
957 improve the performance of waking up a idle CPU, but
958 will use a lot of power and make the system run hot.
959 Not recommended.
960 idle=mwait: On systems which support MONITOR/MWAIT but
961 the kernel chose to not use it because it doesn't save
962 as much power as a normal idle loop, use the
963 MONITOR/MWAIT idle loop anyways. Performance should be
964 the same as idle=poll.
965 idle=halt: Halt is forced to be used for CPU idle.
c1e3b377 966 In such case C2/C3 won't be used again.
ada9cfdd 967 idle=nomwait: Disable mwait for CPU C-states
a9913044 968
79290822
IM
969 ignore_loglevel [KNL]
970 Ignore loglevel setting - this will print /all/
971 kernel messages to the console. Useful for debugging.
972
1da177e4
LT
973 ihash_entries= [KNL]
974 Set number of hash buckets for inode cache.
975
3323eec9
MZ
976 ima_audit= [IMA]
977 Format: { "0" | "1" }
978 0 -- integrity auditing messages. (Default)
979 1 -- enable informational integrity auditing messages.
980
981 ima_hash= [IMA]
a9ed83a5 982 Format: { "sha1" | "md5" }
3323eec9
MZ
983 default: "sha1"
984
5789ba3b
EP
985 ima_tcb [IMA]
986 Load a policy which meets the needs of the Trusted
987 Computing Base. This means IMA will measure all
988 programs exec'd, files mmap'd for exec, and all files
989 opened for read by uid=0.
990
1da177e4
LT
991 in2000= [HW,SCSI]
992 See header of drivers/scsi/in2000.c.
993
994 init= [KNL]
995 Format: <full_path>
996 Run specified binary instead of /sbin/init as init
997 process.
998
999 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1000 for working out where the kernel is dying during
1001 startup.
1002
1003 initrd= [BOOT] Specify the location of the initial ramdisk
1004
1005 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1006 Format: <irq>
1007
ba395927 1008 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
0cd5c3c8
KM
1009 on
1010 Enable intel iommu driver.
ba395927
KA
1011 off
1012 Disable intel iommu driver.
1013 igfx_off [Default Off]
1014 By default, gfx is mapped as normal device. If a gfx
1015 device has a dedicated DMAR unit, the DMAR unit is
1016 bypassed by not enabling DMAR with this option. In
1017 this case, gfx device will use physical address for
1018 DMA.
7d3b03ce
KA
1019 forcedac [x86_64]
1020 With this option iommu will not optimize to look
1021 for io virtual address below 32 bit forcing dual
1022 address cycle on pci bus for cards supporting greater
1023 than 32 bit addressing. The default is to look
1024 for translation below 32 bit and if not available
1025 then look in the higher range.
5e0d2a6f 1026 strict [Default Off]
1027 With this option on every unmap_single operation will
1028 result in a hardware IOTLB flush operation as opposed
1029 to batching them for performance.
ba395927 1030
0cb55ad2
RD
1031 inttest= [IA64]
1032
1033 iomem= Disable strict checking of access to MMIO memory
1034 strict regions from userspace.
1035 relaxed
1036
1037 iommu= [x86]
1038 off
1039 force
1040 noforce
1041 biomerge
1042 panic
1043 nopanic
1044 merge
1045 nomerge
1046 forcesac
1047 soft
4ed0d3e6 1048 pt [x86, IA64]
0cb55ad2
RD
1049
1050 io7= [HW] IO7 for Marvel based alpha systems
1051 See comment before marvel_specify_io7 in
1052 arch/alpha/kernel/core_marvel.c.
1053
6cececfc 1054 io_delay= [X86] I/O delay method
6e7c4025
IM
1055 0x80
1056 Standard port 0x80 based delay
1057 0xed
1058 Alternate port 0xed based delay (needed on some systems)
b02aae9c 1059 udelay
6e7c4025
IM
1060 Simple two microseconds delay
1061 none
1062 No delay
b02aae9c 1063
1da177e4 1064 ip= [IP_PNP]
dc7a0816 1065 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1066
1067 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
1068 See comment before ip2_setup() in
1069 drivers/char/ip2/ip2base.c.
1da177e4
LT
1070
1071 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1072 See header of drivers/scsi/ips.c.
1073
200803df
AC
1074 irqfixup [HW]
1075 When an interrupt is not handled search all handlers
1076 for it. Intended to get systems with badly broken
1077 firmware running.
1078
1079 irqpoll [HW]
1080 When an interrupt is not handled search all handlers
1081 for it. Also check all handlers each timer
1082 interrupt. Intended to get systems with badly broken
1083 firmware running.
1084
1da177e4 1085 isapnp= [ISAPNP]
a9913044 1086 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
1087
1088 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
1089 Format:
1090 <cpu number>,...,<cpu number>
1091 or
b225d44e
LZ
1092 <cpu number>-<cpu number>
1093 (must be a positive range in ascending order)
22f2e280
DF
1094 or a mixture
1095 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 1096
1da177e4
LT
1097 This option can be used to specify one or more CPUs
1098 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
1099 algorithms. You can move a process onto or off an
1100 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
1101 <cpu number> begins at 0 and the maximum value is
1102 "number of CPUs in system - 1".
1103
1104 This option is the preferred way to isolate CPUs. The
a9913044
RD
1105 alternative -- manually setting the CPU mask of all
1106 tasks in the system -- can cause problems and
1107 suboptimal load balancer performance.
1da177e4 1108
a9913044 1109 iucv= [HW,NET]
1da177e4
LT
1110
1111 js= [HW,JOY] Analog joystick
1112 See Documentation/input/joystick.txt.
1113
0cb55ad2
RD
1114 keepinitrd [HW,ARM]
1115
6cececfc 1116 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
ed7ed365
MG
1117 specifies the amount of memory usable by the kernel
1118 for non-movable allocations. The requested amount is
1119 spread evenly throughout all nodes in the system. The
1120 remaining memory in each node is used for Movable
1121 pages. In the event, a node is too small to have both
1122 kernelcore and Movable pages, kernelcore pages will
1123 take priority and other nodes will have a larger number
1124 of kernelcore pages. The Movable zone is used for the
1125 allocation of pages that may be reclaimed or moved
1126 by the page migration subsystem. This means that
1127 HugeTLB pages may not be allocated from this zone.
1128 Note that allocations like PTEs-from-HighMem still
1129 use the HighMem zone if it exists, and the Normal
1130 zone if it does not.
1131
4fe1da4e
JW
1132 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1133 Format: <Controller#>[,poll interval]
1134 The controller # is the number of the ehci usb debug
1135 port as it is probed via PCI. The poll interval is
1136 optional and is the number seconds in between
1137 each poll cycle to the debug port in case you need
1138 the functionality for interrupting the kernel with
1139 gdb or control-c on the dbgp connection. When
1140 not using this parameter you use sysrq-g to break into
1141 the kernel debugger.
1142
84c08fd6 1143 kgdboc= [KGDB,HW] kgdb over consoles.
ada64e4c
JW
1144 Requires a tty driver that supports console polling,
1145 or a supported polling keyboard driver (non-usb).
1146 Serial only format: <serial_device>[,baud]
1147 keyboard only format: kbd
1148 keyboard and serial format: kbd,<serial_device>[,baud]
6cdf6e06 1149
84c08fd6
JW
1150 kgdbwait [KGDB] Stop kernel execution and enter the
1151 kernel debugger at the earliest opportunity.
1152
9bed90c6
FF
1153 kmac= [MIPS] korina ethernet MAC address.
1154 Configure the RouterBoard 532 series on-chip
1155 Ethernet adapter MAC address.
1156
04f70336
CM
1157 kmemleak= [KNL] Boot-time kmemleak enable/disable
1158 Valid arguments: on, off
1159 Default: on
1160
6cececfc 1161 kstack=N [X86] Print N words from the kernel stack
0cb55ad2
RD
1162 in oops dumps.
1163
fef07aae
AP
1164 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1165 Default is 0 (don't ignore, but inject #GP)
1166
1167 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1168 Default is 1 (enabled)
1169
1170 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1171 Default is 0 (off)
1172
1173 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1174 for all guests.
1175 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1176
1177 kvm-intel.bypass_guest_pf=
1178 [KVM,Intel] Disables bypassing of guest page faults
1179 on Intel chips. Default is 1 (enabled)
1180
1181 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1182 (virtualized MMU) support on capable Intel chips.
1183 Default is 1 (enabled)
1184
1185 kvm-intel.emulate_invalid_guest_state=
1186 [KVM,Intel] Enable emulation of invalid guest states
1187 Default is 0 (disabled)
1188
1189 kvm-intel.flexpriority=
1190 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1191 Default is 1 (enabled)
1192
1193 kvm-intel.unrestricted_guest=
1194 [KVM,Intel] Disable unrestricted guest feature
1195 (virtualized real and unpaged mode) on capable
1196 Intel chips. Default is 1 (enabled)
1197
1198 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1199 feature (tagged TLBs) on capable Intel chips.
1200 Default is 1 (enabled)
1201
1da177e4
LT
1202 l2cr= [PPC]
1203
a78bfbfc
RB
1204 l3cr= [PPC]
1205
cd4f0ef7 1206 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1207 disabled it.
1da177e4 1208
6cececfc 1209 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
ada9cfdd 1210 in C2 power state.
e585bef8 1211
fcb71f6f
FC
1212 libata.dma= [LIBATA] DMA control
1213 libata.dma=0 Disable all PATA and SATA DMA
1214 libata.dma=1 PATA and SATA Disk DMA only
1215 libata.dma=2 ATAPI (CDROM) DMA only
1216 libata.dma=4 Compact Flash DMA only
1217 Combinations also work, so libata.dma=3 enables DMA
1218 for disks and CDROMs, but not CFs.
20308871
MP
1219
1220 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1221 libata.ignore_hpa=0 keep BIOS limits (default)
1222 libata.ignore_hpa=1 ignore limits, using full disk
fcb71f6f 1223
78e70c23
DJ
1224 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1225 when set.
1226 Format: <int>
1227
33267325
TH
1228 libata.force= [LIBATA] Force configurations. The format is comma
1229 separated list of "[ID:]VAL" where ID is
4c44f309 1230 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
33267325
TH
1231 matching port, link or device. Basically, it matches
1232 the ATA ID string printed on console by libata. If
1233 the whole ID part is omitted, the last PORT and DEVICE
1234 values are used. If ID hasn't been specified yet, the
1235 configuration applies to all ports, links and devices.
1236
1237 If only DEVICE is omitted, the parameter applies to
1238 the port and all links and devices behind it. DEVICE
1239 number of 0 either selects the first device or the
1240 first fan-out link behind PMP device. It does not
1241 select the host link. DEVICE number of 15 selects the
1242 host link and device attached to it.
1243
1244 The VAL specifies the configuration to force. As long
1245 as there's no ambiguity shortcut notation is allowed.
1246 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1247 The following configurations can be forced.
1248
1249 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1250 Any ID with matching PORT is used.
1251
1252 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1253
1254 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1255 udma[/][16,25,33,44,66,100,133] notation is also
1256 allowed.
1257
1258 * [no]ncq: Turn on or off NCQ.
1259
05944bdf
TH
1260 * nohrst, nosrst, norst: suppress hard, soft
1261 and both resets.
1262
43c9c591
TH
1263 * dump_id: dump IDENTIFY data.
1264
33267325
TH
1265 If there are multiple matching configurations changing
1266 the same attribute, the last one is used.
1267
7c4be253
RD
1268 lmb=debug [KNL] Enable lmb debug messages.
1269
1da177e4 1270 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1271 See Documentation/blockdev/ramdisk.txt.
1da177e4 1272
a6b25b67
RD
1273 lockd.nlm_grace_period=P [NFS] Assign grace period.
1274 Format: <integer>
1da177e4 1275
a6b25b67
RD
1276 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1277 Format: <integer>
1278
1279 lockd.nlm_timeout=T [NFS] Assign timeout value.
1280 Format: <integer>
1281
1282 lockd.nlm_udpport=M [NFS] Assign UDP port.
1283 Format: <integer>
1da177e4
LT
1284
1285 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1286 Format: <irq>
1287
1288 loglevel= All Kernel Messages with a loglevel smaller than the
1289 console loglevel will be printed to the console. It can
1290 also be changed with klogd or other programs. The
1291 loglevels are defined as follows:
1292
1293 0 (KERN_EMERG) system is unusable
1294 1 (KERN_ALERT) action must be taken immediately
1295 2 (KERN_CRIT) critical conditions
1296 3 (KERN_ERR) error conditions
1297 4 (KERN_WARNING) warning conditions
1298 5 (KERN_NOTICE) normal but significant condition
1299 6 (KERN_INFO) informational
1300 7 (KERN_DEBUG) debug-level messages
1301
1302 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1303 Format: { n | nk | nM }
1304 n must be a power of two. The default size
1305 is set in the kernel config file.
1da177e4 1306
accaa24c
RD
1307 logo.nologo [FB] Disables display of the built-in Linux logo.
1308 This may be used to provide more screen space for
1309 kernel log messages and is useful when debugging
1310 kernel boot problems.
1311
1da177e4
LT
1312 lp=0 [LP] Specify parallel ports to use, e.g,
1313 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1314 lp=reset first parallel port). 'lp=0' disables the
1315 lp=auto printer driver. 'lp=reset' (which can be
1316 specified in addition to the ports) causes
1317 attached printers to be reset. Using
1318 lp=port1,port2,... specifies the parallel ports
1319 to associate lp devices with, starting with
1320 lp0. A port specification may be 'none' to skip
1321 that lp device, or a parport name such as
1322 'parport0'. Specifying 'lp=auto' instead of a
1323 port specification list means that device IDs
1324 from each port should be examined, to see if
1325 an IEEE 1284-compliant printer is attached; if
1326 so, the driver will manage that printer.
1327 See also header of drivers/char/lp.c.
1328
1329 lpj=n [KNL]
1330 Sets loops_per_jiffy to given constant, thus avoiding
1331 time-consuming boot-time autodetection (up to 250 ms per
1332 CPU). 0 enables autodetection (default). To determine
1333 the correct value for your kernel, boot with normal
1334 autodetection and see what value is printed. Note that
1335 on SMP systems the preset will be applied to all CPUs,
1336 which is likely to cause problems if your CPUs need
1337 significantly divergent settings. An incorrect value
1338 will cause delays in the kernel to be wrong, leading to
1339 unpredictable I/O errors and other breakage. Although
1340 unlikely, in the extreme case this might damage your
1341 hardware.
1342
1343 ltpc= [NET]
1344 Format: <io>,<irq>,<dma>
1345
a9913044
RD
1346 mac5380= [HW,SCSI] Format:
1347 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1348
a9913044
RD
1349 machvec= [IA64] Force the use of a particular machine-vector
1350 (machvec) in a generic kernel.
1351 Example: machvec=hpzx1_swiotlb
1da177e4 1352
3209e70e
WZ
1353 machtype= [Loongson] Share the same kernel image file between different
1354 yeeloong laptop.
1355 Example: machtype=lemote-yeeloong-2f-7inch
1356
0cb55ad2
RD
1357 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1358 than or equal to this physical address is ignored.
1da177e4
LT
1359
1360 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1361 should make use of. maxcpus=n : n >= 0 limits the
1362 kernel to using 'n' processors. n=0 is a special case,
1363 it is equivalent to "nosmp", which also disables
1364 the IO APIC.
1da177e4 1365
0cb55ad2
RD
1366 max_loop= [LOOP] Maximum number of loopback devices that can
1367 be mounted
1368 Format: <1-256>
2b2c3750 1369
a9913044 1370 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1371 Should be between 1 and 2^32-1.
1372
1373 max_report_luns=
a9913044 1374 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1375 Should be between 1 and 16384.
1376
1da177e4
LT
1377 mcatest= [IA-64]
1378
cd4f0ef7 1379 mce [X86-32] Machine Check Exception
1da177e4 1380
71cced6e 1381 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1382
1da177e4
LT
1383 md= [HW] RAID subsystems devices and level
1384 See Documentation/md.txt.
a9913044 1385
1da177e4
LT
1386 mdacon= [MDA]
1387 Format: <first>,<last>
1388 Specifies range of consoles to be captured by the MDA.
a9913044 1389
1da177e4
LT
1390 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1391 Amount of memory to be used when the kernel is not able
1392 to see the whole system memory or for test.
cd4f0ef7 1393 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1394 address space collisions. Without memmap= PCI devices
1395 could be placed at addresses belonging to unused RAM.
1396
cd4f0ef7 1397 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1398 memory.
1399
6902aa84
PM
1400 memchunk=nn[KMG]
1401 [KNL,SH] Allow user to override the default size for
1402 per-device physically contiguous DMA buffers.
1403
6cececfc 1404 memmap=exactmap [KNL,X86] Enable setting of an exact
1da177e4
LT
1405 E820 memory map, as specified by the user.
1406 Such memmap=exactmap lines can be constructed based on
1407 BIOS output or other requirements. See the memmap=nn@ss
1408 option description.
1409
1410 memmap=nn[KMG]@ss[KMG]
1411 [KNL] Force usage of a specific region of memory
1412 Region of memory to be used, from ss to ss+nn.
1413
1414 memmap=nn[KMG]#ss[KMG]
1415 [KNL,ACPI] Mark specific memory as ACPI data.
1416 Region of memory to be used, from ss to ss+nn.
1417
1418 memmap=nn[KMG]$ss[KMG]
1419 [KNL,ACPI] Mark specific memory as reserved.
1420 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1421 Example: Exclude memory from 0x18690000-0x1869ffff
1422 memmap=64K$0x18690000
1423 or
1424 memmap=0x10000$0x18690000
1da177e4 1425
9f077871
JF
1426 memory_corruption_check=0/1 [X86]
1427 Some BIOSes seem to corrupt the first 64k of
1428 memory when doing things like suspend/resume.
1429 Setting this option will scan the memory
1430 looking for corruption. Enabling this will
1431 both detect corruption and prevent the kernel
1432 from using the memory being corrupted.
1433 However, its intended as a diagnostic tool; if
1434 repeatable BIOS-originated corruption always
1435 affects the same memory, you can use memmap=
1436 to prevent the kernel from using that memory.
1437
1438 memory_corruption_check_size=size [X86]
1439 By default it checks for corruption in the low
1440 64k, making this memory unavailable for normal
1441 use. Use this parameter to scan for
1442 corruption in more or less memory.
1443
1444 memory_corruption_check_period=seconds [X86]
1445 By default it checks for corruption every 60
1446 seconds. Use this parameter to check at some
1447 other rate. 0 disables periodic checking.
1448
caadbdce 1449 memtest= [KNL,X86] Enable memtest
c64df707 1450 Format: <integer>
c64df707 1451 default : 0 <disable>
9e5f6cf5
AH
1452 Specifies the number of memtest passes to be
1453 performed. Each pass selects another test
1454 pattern from a given set of patterns. Memtest
1455 fills the memory with this pattern, validates
1456 memory contents and reserves bad memory
1457 regions that are detected.
c64df707 1458
1da177e4
LT
1459 meye.*= [HW] Set MotionEye Camera parameters
1460 See Documentation/video4linux/meye.txt.
1461
8f36881b
AS
1462 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1463 Multi-Function General Purpose Timers on AMD Geode
1464 platforms.
1465
e6c4dc6c
WT
1466 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1467 the BIOS has incorrectly applied a workaround. TinyBIOS
1468 version 0.98 is known to be affected, 0.99 fixes the
1469 problem by letting the user disable the workaround.
1470
1da177e4
LT
1471 mga= [HW,DRM]
1472
1c207f95
RD
1473 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1474 physical address is ignored.
1475
39f45d7b
MP
1476 mini2440= [ARM,HW,KNL]
1477 Format:[0..2][b][c][t]
1478 Default: "0tb"
1479 MINI2440 configuration specification:
1480 0 - The attached screen is the 3.5" TFT
1481 1 - The attached screen is the 7" TFT
1482 2 - The VGA Shield is attached (1024x768)
1483 Leaving out the screen size parameter will not load
1484 the TFT driver, and the framebuffer will be left
1485 unconfigured.
1486 b - Enable backlight. The TFT backlight pin will be
1487 linked to the kernel VESA blanking code and a GPIO
1488 LED. This parameter is not necessary when using the
1489 VGA shield.
1490 c - Enable the s3c camera interface.
1491 t - Reserved for enabling touchscreen support. The
1492 touchscreen support is not enabled in the mainstream
1493 kernel as of 2.6.30, a preliminary port can be found
1494 in the "bleeding edge" mini2440 support kernel at
1495 http://repo.or.cz/w/linux-2.6/mini2440.git
1496
6b74ab97
MG
1497 mminit_loglevel=
1498 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1499 parameter allows control of the logging verbosity for
1500 the additional memory initialisation checks. A value
1501 of 0 disables mminit logging and a level of 4 will
1502 log everything. Information is printed at KERN_DEBUG
1503 so loglevel=8 may also need to be specified.
1504
1da177e4
LT
1505 mousedev.tap_time=
1506 [MOUSE] Maximum time between finger touching and
1507 leaving touchpad surface for touch to be considered
1508 a tap and be reported as a left button click (for
1509 touchpads working in absolute mode only).
1510 Format: <msecs>
1511 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1512 reporting absolute coordinates, such as tablets
1513 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1514 reporting absolute coordinates, such as tablets
1515
6cececfc 1516 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
0cb55ad2
RD
1517 is similar to kernelcore except it specifies the
1518 amount of memory used for migratable allocations.
1519 If both kernelcore and movablecore is specified,
1520 then kernelcore will be at *least* the specified
1521 value but may be more. If movablecore on its own
1522 is specified, the administrator must be careful
1523 that the amount of memory usable for all allocations
1524 is not too small.
1525
1da177e4
LT
1526 mpu401= [HW,OSS]
1527 Format: <io>,<irq>
1528
1529 MTD_Partition= [MTD]
1530 Format: <name>,<region-number>,<size>,<offset>
1531
a9913044
RD
1532 MTD_Region= [MTD] Format:
1533 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1534
1535 mtdparts= [MTD]
c8facbb6 1536 See drivers/mtd/cmdlinepart.c.
1da177e4 1537
5988af23
RH
1538 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1539
1540 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1541
1542 boundary - index of last SLC block on Flex-OneNAND.
1543 The remaining blocks are configured as MLC blocks.
1544 lock - Configure if Flex-OneNAND boundary should be locked.
1545 Once locked, the boundary cannot be changed.
1546 1 indicates lock status, 0 indicates unlock status.
1547
9db829f4
BD
1548 mtdset= [ARM]
1549 ARM/S3C2412 JIVE boot control
1550
1551 See arch/arm/mach-s3c2412/mach-jive.c
1552
1da177e4 1553 mtouchusb.raw_coordinates=
a9913044
RD
1554 [HW] Make the MicroTouch USB driver use raw coordinates
1555 ('y', default) or cooked coordinates ('n')
1da177e4 1556
0cb55ad2 1557 mtrr_chunk_size=nn[KMG] [X86]
19f59460 1558 used for mtrr cleanup. It is largest continuous chunk
0cb55ad2
RD
1559 that could hold holes aka. UC entries.
1560
1561 mtrr_gran_size=nn[KMG] [X86]
1562 Used for mtrr cleanup. It is granularity of mtrr block.
1563 Default is 1.
1564 Large value could prevent small alignment from
1565 using up MTRRs.
1566
1567 mtrr_spare_reg_nr=n [X86]
1568 Format: <integer>
1569 Range: 0,7 : spare reg number
1570 Default : 1
1571 Used for mtrr cleanup. It is spare mtrr entries number.
1572 Set to 2 or more if your graphical card needs more.
1573
1da177e4
LT
1574 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1575
1576 NCR_D700= [HW,SCSI]
1577 See header of drivers/scsi/NCR_D700.c.
1578
1579 ncr5380= [HW,SCSI]
1580
1581 ncr53c400= [HW,SCSI]
1582
1583 ncr53c400a= [HW,SCSI]
1584
1585 ncr53c406a= [HW,SCSI]
1586
1587 ncr53c8xx= [HW,SCSI]
1588
1589 netdev= [NET] Network devices parameters
1590 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1591 Note that mem_start is often overloaded to mean
1592 something different and driver-specific.
a9913044
RD
1593 This usage is only documented in each driver source
1594 file if at all.
1595
58401572
KPO
1596 nf_conntrack.acct=
1597 [NETFILTER] Enable connection tracking flow accounting
1598 0 to disable accounting
1599 1 to enable accounting
d70a011d 1600 Default value is 0.
58401572 1601
1da177e4 1602 nfsaddrs= [NFS]
dc7a0816 1603 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1604
1605 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
dc7a0816 1606 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4 1607
a72b4422
TM
1608 nfs.callback_tcpport=
1609 [NFS] set the TCP port on which the NFSv4 callback
1610 channel should listen.
1611
e571cbf1
TM
1612 nfs.cache_getent=
1613 [NFS] sets the pathname to the program which is used
1614 to update the NFS client cache entries.
1615
1616 nfs.cache_getent_timeout=
1617 [NFS] sets the timeout after which an attempt to
1618 update a cache entry is deemed to have failed.
1619
58df095b
TM
1620 nfs.idmap_cache_timeout=
1621 [NFS] set the maximum lifetime for idmapper cache
1622 entries.
1623
f43bf0be
TM
1624 nfs.enable_ino64=
1625 [NFS] enable 64-bit inode numbers.
1626 If zero, the NFS client will fake up a 32-bit inode
1627 number for the readdir() and stat() syscalls instead
1628 of returning the full 64-bit number.
1629 The default is to return 64-bit inode numbers.
1630
1e1030dc 1631 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
e7ba176b
HS
1632 when a NMI is triggered.
1633 Format: [state][,regs][,debounce][,die]
1634
6cececfc 1635 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
5b9a0e14
CG
1636 Format: [panic,][num]
1637 Valid num: 0,1,2
1638 0 - turn nmi_watchdog off
1639 1 - use the IO-APIC timer for the NMI watchdog
1640 2 - use the local APIC for the NMI watchdog using
0cb55ad2
RD
1641 a performance counter. Note: This will use one
1642 performance counter and the local APIC's performance
1643 vector.
1644 When panic is specified, panic when an NMI watchdog
1645 timeout occurs.
1646 This is useful when you use a panic=... timeout and
1647 need the box quickly up again.
5b9a0e14
CG
1648 Instead of 1 and 2 it is possible to use the following
1649 symbolic names: lapic and ioapic
1650 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1da177e4 1651
bff38771
AV
1652 netpoll.carrier_timeout=
1653 [NET] Specifies amount of time (in seconds) that
1654 netpoll should wait for a carrier. By default netpoll
1655 waits 4 seconds.
1656
cd4f0ef7 1657 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1658 emulation library even if a 387 maths coprocessor
1659 is present.
1660
0cb55ad2
RD
1661 no_console_suspend
1662 [HW] Never suspend the console
1663 Disable suspending of consoles during suspend and
1664 hibernate operations. Once disabled, debugging
1665 messages can reach various consoles while the rest
1666 of the system is being put to sleep (ie, while
1667 debugging driver suspend/resume hooks). This may
1668 not work reliably with all consoles, but is known
1669 to work with serial and VGA consoles.
1670
c1aee215
CL
1671 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1672 caches in the slab allocator. Saves per-node memory,
1673 but will impact performance.
3395ee05 1674
a9913044
RD
1675 noalign [KNL,ARM]
1676
1da177e4
LT
1677 noapic [SMP,APIC] Tells the kernel to not make use of any
1678 IOAPICs that may be present in the system.
1679
1da177e4
LT
1680 nobats [PPC] Do not use BATs for mapping kernel lowmem
1681 on "Classic" PPC cores.
1682
1683 nocache [ARM]
a9913044 1684
0cb55ad2
RD
1685 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1686
163ecdff
SN
1687 nodelayacct [KNL] Disable per-task delay accounting
1688
1da177e4
LT
1689 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1690
6902aa84
PM
1691 nodsp [SH] Disable hardware DSP at boot time.
1692
6cececfc 1693 noefi [X86] Disable EFI runtime services support.
8b2cb7a8 1694
1da177e4
LT
1695 noexec [IA-64]
1696
6cececfc 1697 noexec [X86]
f5a1b191 1698 On X86-32 available only on PAE configured kernels.
1da177e4 1699 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1700 noexec=off: disable non-executable mappings
1701
1702 noexec32 [X86-64]
1703 This affects only 32-bit executables.
1704 noexec32=on: enable non-executable mappings (default)
1705 read doesn't imply executable mappings
1706 noexec32=off: disable non-executable mappings
1707 read implies executable mappings
1da177e4 1708
6902aa84
PM
1709 nofpu [SH] Disable hardware FPU at boot time.
1710
cd4f0ef7 1711 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1712 register save and restore. The kernel will only save
1713 legacy floating-point registers on task switch.
1da177e4 1714
0c752a93
SS
1715 noxsave [BUGS=X86] Disables x86 extended register state save
1716 and restore using xsave. The kernel will fallback to
1717 enabling legacy floating-point and sse state.
1718
01a24d2b
PZ
1719 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1720 wfi(ARM) instruction doesn't work correctly and not to
1721 use it. This is also useful when using JTAG debugger.
a9913044 1722
cd4f0ef7 1723 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1724 instruction doesn't work correctly and not to
1725 use it.
1726
1f29fae2
SH
1727 no_file_caps Tells the kernel not to honor file capabilities. The
1728 only way then for a file to be executed with privilege
1729 is to be setuid root or executed by root.
1730
1da177e4
LT
1731 nohalt [IA-64] Tells the kernel not to use the power saving
1732 function PAL_HALT_LIGHT when idle. This increases
1733 power-consumption. On the positive side, it reduces
1734 interrupt wake-up latency, which may improve performance
1735 in certain environments such as networked servers or
1736 real-time systems.
1737
79bf2bb3
TG
1738 nohz= [KNL] Boottime enable/disable dynamic ticks
1739 Valid arguments: on, off
1740 Default: on
1741
eeee7853
PM
1742 noiotrap [SH] Disables trapped I/O port accesses.
1743
cd4f0ef7 1744 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1745 disable unhandled interrupt sources.
1746
6cececfc 1747 no_timer_check [X86,APIC] Disables the code which tests for
8542b200
ZA
1748 broken timer IRQ sources.
1749
1da177e4
LT
1750 noisapnp [ISAPNP] Disables ISA PnP code.
1751
1752 noinitrd [RAM] Tells the kernel not to load any configured
1753 initial RAM disk.
1754
03ea8155
WH
1755 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1756 remapping.
1757
1da177e4
LT
1758 nointroute [IA-64]
1759
0aa366f3
TL
1760 nojitter [IA64] Disables jitter checking for ITC timers.
1761
cd4f0ef7 1762 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1763
cd4f0ef7 1764 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1765
1da177e4
LT
1766 noltlbs [PPC] Do not use large page/tlb entries for kernel
1767 lowmem mapping on PPC40x.
1768
312f1f01
H
1769 nomca [IA-64] Disable machine check abort handling
1770
cd4f0ef7 1771 nomce [X86-32] Machine Check Exception
abe37e5a 1772
83d7384f
AS
1773 nomfgpt [X86-32] Disable Multi-Function General Purpose
1774 Timer usage (for AMD Geode machines).
1775
016ddd9b
JK
1776 nopat [X86] Disable PAT (page attribute table extension of
1777 pagetables) support.
1778
0cb55ad2
RD
1779 norandmaps Don't use address space randomization. Equivalent to
1780 echo 0 > /proc/sys/kernel/randomize_va_space
1781
cd4f0ef7 1782 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1783
cd4f0ef7 1784 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1785 with UP alternatives
1786
1da177e4
LT
1787 noresidual [PPC] Don't use residual data on PReP machines.
1788
a9913044
RD
1789 noresume [SWSUSP] Disables resume and restores original swap
1790 space.
1791
1da177e4
LT
1792 no-scroll [VGA] Disables scrollback.
1793 This is required for the Braillex ib80-piezo Braille
1794 reader made by F.H. Papenmeier (Germany).
1795
1796 nosbagart [IA-64]
1797
cd4f0ef7 1798 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1799
61ec7567
LB
1800 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1801 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1802
97842216
DJ
1803 nosoftlockup [KNL] Disable the soft-lockup detector.
1804
c077719b 1805 noswapaccount [KNL] Disable accounting of swap in memory resource
21acb9ca 1806 controller. (See Documentation/cgroups/memory.txt)
c077719b 1807
1da177e4
LT
1808 nosync [HW,M68K] Disables sync negotiation for all devices.
1809
cd4f0ef7 1810 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1811
1812 nousb [USB] Disable the USB subsystem
1813
1814 nowb [ARM]
a9913044 1815
2b2fd87a
WH
1816 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1817
a6c75b86
FY
1818 nptcg= [IA64] Override max number of concurrent global TLB
1819 purges which is reported from either PAL_VM_SUMMARY or
1820 SAL PALO.
1821
2b633e3f
YL
1822 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1823 could support. nr_cpus=n : n >= 1 limits the kernel to
1824 supporting 'n' processors. Later in runtime you can not
1825 use hotplug cpu feature to put more cpu back to online.
1826 just like you compile the kernel NR_CPUS=n
1827
0cb55ad2
RD
1828 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1829
f0c0b2b8
KH
1830 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1831 one of ['zone', 'node', 'default'] can be specified
1832 This can be set from sysctl after boot.
1833 See Documentation/sysctl/vm.txt for details.
1834
7c4be253
RD
1835 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1836 See Documentation/debugging-via-ohci1394.txt for more
1837 info.
1838
3ef0e1f8
AS
1839 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1840 Rather than timing out after 20 ms if an EC
1841 command is not properly ACKed, override the length
1842 of the timeout. We have interrupts disabled while
1843 waiting for the ACK, so if this is set too high
1844 interrupts *may* be lost!
1845
15ac7afe
TL
1846 omap_mux= [OMAP] Override bootloader pin multiplexing.
1847 Format: <mux_mode0.mode_name=value>...
1848 For example, to override I2C bus2:
1849 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1850
1da177e4
LT
1851 opl3= [HW,OSS]
1852 Format: <io>
1853
1da177e4
LT
1854 oprofile.timer= [HW]
1855 Use timer interrupt instead of performance counters
1856
7e4e0bd5
RR
1857 oprofile.cpu_type= Force an oprofile cpu type
1858 This might be useful if you have an older oprofile
1859 userland or if you want common events.
8d7ff4f2
RR
1860 Format: { arch_perfmon }
1861 arch_perfmon: [X86] Force use of architectural
7e4e0bd5
RR
1862 perfmon on Intel CPUs instead of the
1863 CPU specific event set.
1dcdb5a9 1864
1da177e4
LT
1865 osst= [HW,SCSI] SCSI Tape Driver
1866 Format: <buffer_size>,<write_threshold>
1867 See also Documentation/scsi/st.txt.
1868
1869 panic= [KNL] Kernel behaviour on panic
1870 Format: <timeout>
1871
1872 parkbd.port= [HW] Parallel port number the keyboard adapter is
1873 connected to, default is 0.
1874 Format: <parport#>
1875 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1876 0 for XT, 1 for AT (default is AT).
a9913044
RD
1877 Format: <mode>
1878
1879 parport= [HW,PPT] Specify parallel ports. 0 disables.
1880 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1881 Use 'auto' to force the driver to use any
1882 IRQ/DMA settings detected (the default is to
1883 ignore detected IRQ/DMA settings because of
1884 possible conflicts). You can specify the base
1885 address, IRQ, and DMA settings; IRQ and DMA
1886 should be numbers, or 'auto' (for using detected
1887 settings on that particular port), or 'nofifo'
1888 (to avoid using a FIFO even if it is detected).
1889 Parallel ports are assigned in the order they
1890 are specified on the command line, starting
1891 with parport0.
1892
1893 parport_init_mode= [HW,PPT]
1894 Configure VIA parallel port to operate in
1895 a specific mode. This is necessary on Pegasos
1896 computer where firmware has no options for setting
1897 up parallel port mode and sets it to spp.
1898 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1899 Format: [spp|ps2|epp|ecp|ecpepp]
1900
a9913044
RD
1901 pas2= [HW,OSS] Format:
1902 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1903
1da177e4
LT
1904 pas16= [HW,SCSI]
1905 See header of drivers/scsi/pas16.c.
1906
dd287796
AM
1907 pause_on_oops=
1908 Halt all CPUs after the first oops has been printed for
1909 the specified number of seconds. This is to be used if
1910 your oopses keep scrolling off the screen.
1911
1da177e4
LT
1912 pcbit= [HW,ISDN]
1913
1914 pcd. [PARIDE]
1915 See header of drivers/block/paride/pcd.c.
31c00fc1 1916 See also Documentation/blockdev/paride.txt.
1da177e4 1917
a9913044 1918 pci=option[,option...] [PCI] various PCI subsystem options:
1cc0ca26
BH
1919 earlydump [X86] dump PCI config space before the kernel
1920 changes anything
c0115606 1921 off [X86] don't probe for the PCI bus
cd4f0ef7 1922 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1923 the hardware directly. Use this if your machine
1924 has a non-standard PCI host bridge.
cd4f0ef7 1925 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1926 hardware access methods are allowed. Use this
1927 if you experience crashes upon bootup and you
1928 suspect they are caused by the BIOS.
c0115606 1929 conf1 [X86] Force use of PCI Configuration
a9913044 1930 Mechanism 1.
c0115606 1931 conf2 [X86] Force use of PCI Configuration
a9913044 1932 Mechanism 2.
7f785763
RD
1933 noaer [PCIE] If the PCIEAER kernel config parameter is
1934 enabled, this kernel boot option can be used to
1935 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1936 nodomains [PCI] Disable support for multiple PCI
1937 root domains (aka PCI segments, in ACPI-speak).
6cececfc 1938 nommconf [X86] Disable use of MMCONFIG for PCI
61be6d66 1939 Configuration
12983077
AH
1940 check_enable_amd_mmconf [X86] check for and enable
1941 properly configured MMIO access to PCI
1942 config space on AMD family 10h CPU
309e57df
MW
1943 nomsi [MSI] If the PCI_MSI kernel config parameter is
1944 enabled, this kernel boot option can be used to
1945 disable the use of MSI interrupts system-wide.
a9322f64
SA
1946 noioapicquirk [APIC] Disable all boot interrupt quirks.
1947 Safety option to keep boot IRQs enabled. This
1948 should never be necessary.
9197979b
SA
1949 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1950 primary IO-APIC for bridges that cannot disable
1951 boot IRQs. This fixes a source of spurious IRQs
1952 when the system masks IRQs.
41b9eb26
SA
1953 noioapicreroute [APIC] Disable workaround that uses the
1954 boot IRQ equivalent of an IRQ that connects to
1955 a chipset where boot IRQs cannot be disabled.
1956 The opposite of ioapicreroute.
cd4f0ef7 1957 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1958 routing table. These calls are known to be buggy
1959 on several machines and they hang the machine
1960 when used, but on other computers it's the only
1961 way to get the interrupt routing table. Try
1962 this option if the kernel is unable to allocate
1963 IRQs or discover secondary PCI buses on your
1964 motherboard.
c0115606 1965 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1966 Use with caution as certain devices share
1967 address decoders between ROMs and other
1968 resources.
c0115606 1969 norom [X86] Do not assign address space to
bb71ad88
GH
1970 expansion ROMs that do not already have
1971 BIOS assigned address ranges.
c0115606 1972 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1973 assigned automatically to PCI devices. You can
1974 make the kernel exclude IRQs of your ISA cards
1975 this way.
c0115606 1976 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1977 of the PIRQ table (normally generated
1978 by the BIOS) if it is outside the
1979 F0000h-100000h range.
c0115606 1980 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1981 useful if the kernel is unable to find your
1982 secondary buses and you want to tell it
1983 explicitly which ones they are.
c0115606 1984 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1985 numbers ourselves, overriding
1986 whatever the firmware may have done.
c0115606 1987 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1988 in the BIOS $PIR table. This is needed on
1989 some systems with broken BIOSes, notably
1990 some HP Pavilion N5400 and Omnibook XE3
1991 notebooks. This will have no effect if ACPI
1992 IRQ routing is enabled.
c0115606 1993 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1994 or for PCI scanning.
7bc5e3f2
BH
1995 use_crs [X86] Use PCI host bridge window information
1996 from ACPI. On BIOSes from 2008 or later, this
1997 is enabled by default. If you need to use this,
1998 please report a bug.
1999 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2000 If you need to use this, please report a bug.
a9913044
RD
2001 routeirq Do IRQ routing for all PCI devices.
2002 This is normally done in pci_enable_device(),
2003 so this option is a temporary workaround
2004 for broken drivers that don't call it.
13a6ddb0
YL
2005 skip_isa_align [X86] do not align io start addr, so can
2006 handle more pci cards
a9913044
RD
2007 firmware [ARM] Do not re-enumerate the bus but instead
2008 just use the configuration from the
2009 bootloader. This is currently used on
2010 IXP2000 systems where the bus has to be
2011 configured a certain way for adjunct CPUs.
0637a70a
AK
2012 noearly [X86] Don't do any early type 1 scanning.
2013 This might help on some broken boards which
2014 machine check when some devices' config space
2015 is read. But various workarounds are disabled
2016 and some IOMMU drivers will not work.
6b4b78fe
MD
2017 bfsort Sort PCI devices into breadth-first order.
2018 This sorting is done to get a device
2019 order compatible with older (<= 2.4) kernels.
2020 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
2021 cbiosize=nn[KMG] The fixed amount of bus space which is
2022 reserved for the CardBus bridge's IO window.
2023 The default value is 256 bytes.
2024 cbmemsize=nn[KMG] The fixed amount of bus space which is
2025 reserved for the CardBus bridge's memory
2026 window. The default value is 64 megabytes.
32a9a682
YS
2027 resource_alignment=
2028 Format:
2029 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2030 Specifies alignment and device to reassign
2031 aligned memory resources.
2032 If <order of align> is not specified,
2033 PAGE_SIZE is used as alignment.
2034 PCI-PCI bridge can be specified, if resource
2035 windows need to be expanded.
43c16408
AP
2036 ecrc= Enable/disable PCIe ECRC (transaction layer
2037 end-to-end CRC checking).
2038 bios: Use BIOS/firmware settings. This is the
2039 the default.
2040 off: Turn ECRC off
2041 on: Turn ECRC on.
6b4b78fe 2042
e5665a45
CE
2043 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2044 Management.
2045 off Disable ASPM.
2046 force Enable ASPM even on devices that claim not to support it.
2047 WARNING: Forcing ASPM on may cause system lockups.
2048
c7f48656
RW
2049 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2050 off Do not use native PCIe PME signaling.
2051 force Use native PCIe PME signaling even if the BIOS refuses
2052 to allow the kernel to control the relevant PCIe config
2053 registers.
c39fae14
RW
2054 nomsi Do not use MSI for native PCIe PME signaling (this makes
2055 all PCIe root ports use INTx for everything).
c7f48656 2056
1da177e4
LT
2057 pcmv= [HW,PCMCIA] BadgePAD 4
2058
2059 pd. [PARIDE]
31c00fc1 2060 See Documentation/blockdev/paride.txt.
1da177e4
LT
2061
2062 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2063 boot time.
2064 Format: { 0 | 1 }
2065 See arch/parisc/kernel/pdc_chassis.c
2066
f58dc01b 2067 percpu_alloc= Select which percpu first chunk allocator to use.
e933a73f
TH
2068 Currently supported values are "embed" and "page".
2069 Archs may support subset or none of the selections.
2070 See comments in mm/percpu.c for details on each
2071 allocator. This parameter is primarily for debugging
2072 and performance comparison.
fa8a7094 2073
1da177e4 2074 pf. [PARIDE]
31c00fc1 2075 See Documentation/blockdev/paride.txt.
1da177e4
LT
2076
2077 pg. [PARIDE]
31c00fc1 2078 See Documentation/blockdev/paride.txt.
1da177e4
LT
2079
2080 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 2081 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
2082
2083 plip= [PPT,NET] Parallel port network link
2084 Format: { parport<nr> | timid | 0 }
2085 See also Documentation/parport.txt.
2086
de32a243
TG
2087 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2088 Override pmtimer IOPort with a hex value.
2089 e.g. pmtmr=0x508
2090
97ef062b
BH
2091 pnp.debug [PNP]
2092 Enable PNP debug messages. This depends on the
2093 CONFIG_PNP_DEBUG_MESSAGES option.
2094
1da177e4
LT
2095 pnpacpi= [ACPI]
2096 { off }
2097
2098 pnpbios= [ISAPNP]
2099 { on | off | curr | res | no-curr | no-res }
2100
2101 pnp_reserve_irq=
2102 [ISAPNP] Exclude IRQs for the autoconfiguration
2103
2104 pnp_reserve_dma=
2105 [ISAPNP] Exclude DMAs for the autoconfiguration
2106
2107 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 2108 Ranges are in pairs (I/O port base and size).
1da177e4
LT
2109
2110 pnp_reserve_mem=
a9913044
RD
2111 [ISAPNP] Exclude memory regions for the
2112 autoconfiguration.
1da177e4
LT
2113 Ranges are in pairs (memory base and size).
2114
4af94f39
RD
2115 ports= [IP_VS_FTP] IPVS ftp helper module
2116 Default is 21.
2117 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2118 may be specified.
2119 Format: <port>,<port>....
2120
45807a1d
IM
2121 print-fatal-signals=
2122 [KNL] debug: print fatal signals
f84d49b2
NO
2123
2124 If enabled, warn about various signal handling
2125 related application anomalies: too many signals,
2126 too many POSIX.1 timers, fatal signals causing a
2127 coredump - etc.
2128
2129 If you hit the warning due to signal overflow,
2130 you might want to try "ulimit -i unlimited".
2131
45807a1d
IM
2132 default: off.
2133
e84845c4
RD
2134 printk.time= Show timing data prefixed to each printk message line
2135 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2136
0cb55ad2
RD
2137 processor.max_cstate= [HW,ACPI]
2138 Limit processor to maximum C-state
2139 max_cstate=9 overrides any DMI blacklist limit.
2140
2141 processor.nocst [HW,ACPI]
2142 Ignore the _CST method to determine C-states,
2143 instead using the legacy FADT method
2144
1da177e4 2145 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
2146 Format: [schedule,]<number>
2147 Param: "schedule" - profile schedule points.
2148 Param: <number> - step/bucket size as a power of 2 for
2149 statistical time based profiling.
b3da2a73
MG
2150 Param: "sleep" - profile D-state sleeping (millisecs).
2151 Requires CONFIG_SCHEDSTATS
c0fe2e69 2152 Param: "kvm" - profile VM exits.
1da177e4 2153
1da177e4
LT
2154 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2155 before loading.
31c00fc1 2156 See Documentation/blockdev/ramdisk.txt.
1da177e4 2157
a9913044
RD
2158 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2159 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
2160 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2161 per second.
a9913044
RD
2162 psmouse.resetafter= [HW,MOUSE]
2163 Try to reset the device after so many bad packets
1da177e4
LT
2164 (0 = never).
2165 psmouse.resolution=
2166 [HW,MOUSE] Set desired mouse resolution, in dpi.
2167 psmouse.smartscroll=
a9913044 2168 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
2169 0 = disabled, 1 = enabled (default).
2170
2171 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
2172 Format:
2173 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
2174
2175 pt. [PARIDE]
31c00fc1 2176 See Documentation/blockdev/paride.txt.
1da177e4 2177
dc8c8587
KS
2178 pty.legacy_count=
2179 [KNL] Number of legacy pty's. Overwrites compiled-in
2180 default number.
2181
7d2c502f 2182 quiet [KNL] Disable most log messages
a9913044 2183
1da177e4
LT
2184 r128= [HW,DRM]
2185
2186 raid= [HW,RAID]
2187 See Documentation/md.txt.
2188
a9913044 2189 ramdisk_blocksize= [RAM]
31c00fc1 2190 See Documentation/blockdev/ramdisk.txt.
a9913044 2191
1da177e4 2192 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 2193 See Documentation/blockdev/ramdisk.txt.
1da177e4 2194
24aaef8d
RD
2195 rcupdate.blimit= [KNL,BOOT]
2196 Set maximum number of finished RCU callbacks to process
2197 in one batch.
21a1ea9e 2198
24aaef8d
RD
2199 rcupdate.qhimark= [KNL,BOOT]
2200 Set threshold of queued
21a1ea9e
DS
2201 RCU callbacks over which batch limiting is disabled.
2202
24aaef8d
RD
2203 rcupdate.qlowmark= [KNL,BOOT]
2204 Set threshold of queued RCU callbacks below which
2205 batch limiting is re-enabled.
21a1ea9e 2206
ffdfc409
OJ
2207 rdinit= [KNL]
2208 Format: <full_path>
2209 Run specified binary instead of /init from the ramdisk,
2210 used for early userspace startup. See initrd.
2211
cd4f0ef7 2212 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 2213 Format: <reboot_mode>[,<reboot_mode2>[,...]]
ecb08d81 2214 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 2215
46b6d94e
PJ
2216 relax_domain_level=
2217 [KNL, SMP] Set scheduler's default relax_domain_level.
21acb9ca 2218 See Documentation/cgroups/cpusets.txt.
46b6d94e 2219
1da177e4
LT
2220 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2221
cd4f0ef7 2222 reservetop= [X86-32]
461a9aff
ZA
2223 Format: nn[KMG]
2224 Reserves a hole at the top of the kernel virtual
2225 address space.
2226
7e96287d
VG
2227 reset_devices [KNL] Force drivers to reset the underlying device
2228 during initialization.
2229
a9913044
RD
2230 resume= [SWSUSP]
2231 Specify the partition device for software suspend
1da177e4 2232
ecbd0da1
RW
2233 resume_offset= [SWSUSP]
2234 Specify the offset from the beginning of the partition
2235 given by "resume=" at which the swap header is located,
2236 in <PAGE_SIZE> units (needed only for swap files).
2237 See Documentation/power/swsusp-and-swap-files.txt
2238
0a7b35cb
MN
2239 retain_initrd [RAM] Keep initrd memory after extraction
2240
1da177e4
LT
2241 rhash_entries= [KNL,NET]
2242 Set number of hash buckets for route cache
2243
2244 riscom8= [HW,SERIAL]
2245 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2246
2247 ro [KNL] Mount root device read-only on boot
2248
2249 root= [KNL] Root filesystem
2250
2251 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2252 mount the root filesystem
2253
2254 rootflags= [KNL] Set root filesystem mount option string
2255
2256 rootfstype= [KNL] Set root filesystem type
2257
cc1ed754
PO
2258 rootwait [KNL] Wait (indefinitely) for root device to show up.
2259 Useful for devices that are detected asynchronously
2260 (e.g. USB and MMC devices).
2261
1da177e4
LT
2262 rw [KNL] Mount root device read-write on boot
2263
2264 S [KNL] Run init in single mode
2265
2266 sa1100ir [NET]
2267 See drivers/net/irda/sa1100_ir.c.
2268
1da177e4 2269 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 2270
f6630114
MT
2271 sched_debug [KNL] Enables verbose scheduler debug messages.
2272
1da177e4
LT
2273 scsi_debug_*= [SCSI]
2274 See drivers/scsi/scsi_debug.c.
2275
2276 scsi_default_dev_flags=
2277 [SCSI] SCSI default device flags
2278 Format: <integer>
2279
2280 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2281 Format: <vendor>:<model>:<flags>
2282 (flags are integer value)
2283
6af6632a
RD
2284 scsi_logging_level= [SCSI] a bit mask of logging levels
2285 See drivers/scsi/scsi_logging.h for bits. Also
2286 settable via sysctl at dev.scsi.logging_level
2287 (/proc/sys/dev/scsi/logging_level).
2288 There is also a nice 'scsi_logging_level' script in the
2289 S390-tools package, available for download at
2290 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 2291
3e082a91
MW
2292 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2293 discovered. async scans them in kernel threads,
2294 allowing boot to proceed. none ignores them, expecting
2295 user space to do the scan.
2296
0cb55ad2
RD
2297 security= [SECURITY] Choose a security module to enable at boot.
2298 If this boot parameter is not specified, only the first
2299 security module asking for security registration will be
2300 loaded. An invalid security module name will be treated
2301 as if no module has been chosen.
2302
2303 selinux= [SELINUX] Disable or enable SELinux at boot time.
1da177e4
LT
2304 Format: { "0" | "1" }
2305 See security/selinux/Kconfig help text.
2306 0 -- disable.
2307 1 -- enable.
2308 Default value is set via kernel config option.
2309 If enabled at boot time, /selinux/disable can be used
2310 later to disable prior to initial policy load.
2311
cd4f0ef7 2312 serialnumber [BUGS=X86-32]
1da177e4 2313
1da177e4
LT
2314 shapers= [NET]
2315 Maximal number of shapers.
a9913044 2316
b05f78f5
YL
2317 show_msr= [x86] show boot-time MSR settings
2318 Format: { <integer> }
2319 Show boot-time (BIOS-initialized) MSR settings.
2320 The parameter means the number of CPUs to show,
2321 for example 1 means boot CPU only.
2322
1da177e4
LT
2323 sim710= [SCSI,HW]
2324 See header of drivers/scsi/sim710.c.
2325
2326 simeth= [IA-64]
2327 simscsi=
a9913044 2328
1da177e4
LT
2329 slram= [HW,MTD]
2330
f0630fff
CL
2331 slub_debug[=options[,slabs]] [MM, SLUB]
2332 Enabling slub_debug allows one to determine the
2333 culprit if slab objects become corrupted. Enabling
2334 slub_debug can create guard zones around objects and
2335 may poison objects when not in use. Also tracks the
2336 last alloc / free. For more information see
2337 Documentation/vm/slub.txt.
c1aee215
CL
2338
2339 slub_max_order= [MM, SLUB]
f0630fff
CL
2340 Determines the maximum allowed order for slabs.
2341 A high setting may cause OOMs due to memory
2342 fragmentation. For more information see
2343 Documentation/vm/slub.txt.
c1aee215
CL
2344
2345 slub_min_objects= [MM, SLUB]
f0630fff
CL
2346 The minimum number of objects per slab. SLUB will
2347 increase the slab order up to slub_max_order to
2348 generate a sufficiently large slab able to contain
2349 the number of objects indicated. The higher the number
2350 of objects the smaller the overhead of tracking slabs
2351 and the less frequently locks need to be acquired.
c1aee215
CL
2352 For more information see Documentation/vm/slub.txt.
2353
2354 slub_min_order= [MM, SLUB]
2355 Determines the mininum page order for slabs. Must be
f0630fff 2356 lower than slub_max_order.
c1aee215
CL
2357 For more information see Documentation/vm/slub.txt.
2358
2359 slub_nomerge [MM, SLUB]
f0630fff 2360 Disable merging of slabs with similar size. May be
c1aee215 2361 necessary if there is some reason to distinguish
f0630fff
CL
2362 allocs to different slabs. Debug options disable
2363 merging on their own.
c1aee215
CL
2364 For more information see Documentation/vm/slub.txt.
2365
1da177e4
LT
2366 smart2= [HW]
2367 Format: <io1>[,<io2>[,...,<io8>]]
2368
cd4f0ef7 2369 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2370 attempt to substitute SMP alternatives once at boot.
2371
d0d4f69b
BH
2372 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2373 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2374 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2375 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2376 smsc-ircc2.ircc_irq= [HW] IRQ line
2377 smsc-ircc2.ircc_dma= [HW] DMA channel
2378 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2379 0: Toshiba Satellite 1800 (GP data pin select)
2380 1: Fast pin select (default)
2381 2: ATC IRMode
2382
1da177e4
LT
2383 snd-ad1816a= [HW,ALSA]
2384
2385 snd-ad1848= [HW,ALSA]
2386
2387 snd-ali5451= [HW,ALSA]
2388
2389 snd-als100= [HW,ALSA]
2390
2391 snd-als4000= [HW,ALSA]
2392
2393 snd-azt2320= [HW,ALSA]
2394
2395 snd-cmi8330= [HW,ALSA]
2396
2397 snd-cmipci= [HW,ALSA]
2398
2399 snd-cs4231= [HW,ALSA]
2400
2401 snd-cs4232= [HW,ALSA]
2402
2403 snd-cs4236= [HW,ALSA]
2404
2405 snd-cs4281= [HW,ALSA]
2406
2407 snd-cs46xx= [HW,ALSA]
2408
2409 snd-dt019x= [HW,ALSA]
2410
2411 snd-dummy= [HW,ALSA]
2412
2413 snd-emu10k1= [HW,ALSA]
2414
2415 snd-ens1370= [HW,ALSA]
2416
2417 snd-ens1371= [HW,ALSA]
2418
2419 snd-es968= [HW,ALSA]
2420
2421 snd-es1688= [HW,ALSA]
2422
2423 snd-es18xx= [HW,ALSA]
2424
2425 snd-es1938= [HW,ALSA]
2426
2427 snd-es1968= [HW,ALSA]
2428
2429 snd-fm801= [HW,ALSA]
2430
2431 snd-gusclassic= [HW,ALSA]
2432
2433 snd-gusextreme= [HW,ALSA]
2434
2435 snd-gusmax= [HW,ALSA]
2436
2437 snd-hdsp= [HW,ALSA]
2438
2439 snd-ice1712= [HW,ALSA]
2440
2441 snd-intel8x0= [HW,ALSA]
2442
2443 snd-interwave= [HW,ALSA]
2444
2445 snd-interwave-stb=
2446 [HW,ALSA]
2447
2448 snd-korg1212= [HW,ALSA]
2449
2450 snd-maestro3= [HW,ALSA]
2451
2452 snd-mpu401= [HW,ALSA]
2453
2454 snd-mtpav= [HW,ALSA]
2455
2456 snd-nm256= [HW,ALSA]
2457
2458 snd-opl3sa2= [HW,ALSA]
2459
2460 snd-opti92x-ad1848=
2461 [HW,ALSA]
2462
2463 snd-opti92x-cs4231=
2464 [HW,ALSA]
2465
2466 snd-opti93x= [HW,ALSA]
2467
2468 snd-pmac= [HW,ALSA]
2469
2470 snd-rme32= [HW,ALSA]
2471
2472 snd-rme96= [HW,ALSA]
2473
2474 snd-rme9652= [HW,ALSA]
2475
2476 snd-sb8= [HW,ALSA]
2477
2478 snd-sb16= [HW,ALSA]
2479
2480 snd-sbawe= [HW,ALSA]
2481
2482 snd-serial= [HW,ALSA]
2483
2484 snd-sgalaxy= [HW,ALSA]
2485
2486 snd-sonicvibes= [HW,ALSA]
2487
2488 snd-sun-amd7930=
2489 [HW,ALSA]
2490
2491 snd-sun-cs4231= [HW,ALSA]
2492
2493 snd-trident= [HW,ALSA]
2494
2495 snd-usb-audio= [HW,ALSA,USB]
2496
2497 snd-via82xx= [HW,ALSA]
2498
2499 snd-virmidi= [HW,ALSA]
2500
2501 snd-wavefront= [HW,ALSA]
2502
2503 snd-ymfpci= [HW,ALSA]
a9913044 2504
9c44bc03
IM
2505 softlockup_panic=
2506 [KNL] Should the soft-lockup detector generate panics.
2507
1da177e4
LT
2508 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2509 See Documentation/sonypi.txt
2510
2511 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2512 See Documentation/serial/specialix.txt.
1da177e4
LT
2513
2514 spia_io_base= [HW,MTD]
2515 spia_fio_base=
2516 spia_pedr=
2517 spia_peddr=
2518
2519 sscape= [HW,OSS]
2520 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2521
1da177e4
LT
2522 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2523 See Documentation/scsi/st.txt.
2524
f38f1d2a
SR
2525 stacktrace [FTRACE]
2526 Enabled the stack tracer on boot up.
2527
1da177e4
LT
2528 sti= [PARISC,HW]
2529 Format: <num>
2530 Set the STI (builtin display/keyboard on the HP-PARISC
2531 machines) console (graphic card) which should be used
2532 as the initial boot-console.
2533 See also comment in drivers/video/console/sticore.c.
2534
2535 sti_font= [HW]
2536 See comment in drivers/video/console/sticore.c.
2537
2538 stifb= [HW]
2539 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2540
cbf11071
TM
2541 sunrpc.min_resvport=
2542 sunrpc.max_resvport=
2543 [NFS,SUNRPC]
2544 SunRPC servers often require that client requests
2545 originate from a privileged port (i.e. a port in the
2546 range 0 < portnr < 1024).
2547 An administrator who wishes to reserve some of these
2548 ports for other uses may adjust the range that the
2549 kernel's sunrpc client considers to be privileged
2550 using these two parameters to set the minimum and
2551 maximum port values.
2552
42a7fc4a
GB
2553 sunrpc.pool_mode=
2554 [NFS]
2555 Control how the NFS server code allocates CPUs to
2556 service thread pools. Depending on how many NICs
2557 you have and where their interrupts are bound, this
2558 option will affect which CPUs will do NFS serving.
2559 Note: this parameter cannot be changed while the
2560 NFS server is running.
2561
2562 auto the server chooses an appropriate mode
2563 automatically using heuristics
2564 global a single global pool contains all CPUs
2565 percpu one pool for each CPU
2566 pernode one pool for each NUMA node (equivalent
2567 to global on non-NUMA machines)
2568
cbf11071
TM
2569 sunrpc.tcp_slot_table_entries=
2570 sunrpc.udp_slot_table_entries=
2571 [NFS,SUNRPC]
2572 Sets the upper limit on the number of simultaneous
2573 RPC calls that can be sent from the client to a
2574 server. Increasing these values may allow you to
2575 improve throughput, but will also increase the
2576 amount of memory reserved for use by the client.
2577
1da177e4 2578 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2579
1da177e4
LT
2580 switches= [HW,M68k]
2581
2582 sym53c416= [HW,SCSI]
2583 See header of drivers/scsi/sym53c416.c.
2584
5d6f647f
IM
2585 sysrq_always_enabled
2586 [KNL]
2587 Ignore sysrq setting - this boot parameter will
2588 neutralize any effect of /proc/sys/kernel/sysrq.
2589 Useful for debugging.
2590
1da177e4
LT
2591 t128= [HW,SCSI]
2592 See header of drivers/scsi/t128.c.
2593
2594 tdfx= [HW,DRM]
2595
77437fd4
DB
2596 test_suspend= [SUSPEND]
2597 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2598 standby suspend) as the system sleep state to briefly
2599 enter during system startup. The system is woken from
2600 this state using a wakeup-capable RTC alarm.
2601
1da177e4
LT
2602 thash_entries= [KNL,NET]
2603 Set number of hash buckets for TCP connection
2604
f8707ec9
LB
2605 thermal.act= [HW,ACPI]
2606 -1: disable all active trip points in all thermal zones
2607 <degrees C>: override all lowest active trip points
2608
c52a7419
LB
2609 thermal.crt= [HW,ACPI]
2610 -1: disable all critical trip points in all thermal zones
22a94d79 2611 <degrees C>: override all critical trip points
c52a7419 2612
f5487145
LB
2613 thermal.nocrt= [HW,ACPI]
2614 Set to disable actions on ACPI thermal zone
2615 critical and hot trip points.
2616
72b33ef8
LB
2617 thermal.off= [HW,ACPI]
2618 1: disable ACPI thermal control
2619
a70cdc52
LB
2620 thermal.psv= [HW,ACPI]
2621 -1: disable all passive trip points
ada9cfdd
RD
2622 <degrees C>: override all passive trip points to this
2623 value
a70cdc52 2624
730ff34d
LB
2625 thermal.tzp= [HW,ACPI]
2626 Specify global default ACPI thermal zone polling rate
2627 <deci-seconds>: poll all this frequency
2628 0: no polling (default)
2629
1da177e4
LT
2630 tmscsim= [HW,SCSI]
2631 See comment before function dc390_setup() in
2632 drivers/scsi/tmscsim.c.
2633
2b1a61f0
HC
2634 topology= [S390]
2635 Format: {off | on}
2636 Specify if the kernel should make use of the cpu
2637 topology informations if the hardware supports these.
2638 The scheduler will make use of these informations and
2639 e.g. base its process migration decisions on it.
2640 Default is off.
2641
1da177e4
LT
2642 tp720= [HW,PS2]
2643
225a9be2
RA
2644 tpm_suspend_pcr=[HW,TPM]
2645 Format: integer pcr id
2646 Specify that at suspend time, the tpm driver
2647 should extend the specified pcr with zeros,
2648 as a workaround for some chips which fail to
2649 flush the last written pcr on TPM_SaveState.
2650 This will guarantee that all the other pcrs
2651 are saved.
2652
9d612bef
LZ
2653 trace_buf_size=nn[KMG]
2654 [FTRACE] will set tracing buffer size.
631595fb 2655
020e5f85
LZ
2656 trace_event=[event-list]
2657 [FTRACE] Set and start specified trace events in order
2658 to facilitate early boot debugging.
2659 See also Documentation/trace/events.txt
2660
1da177e4 2661 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2662 Format:
2663 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2664
395628ef
AK
2665 tsc= Disable clocksource-must-verify flag for TSC.
2666 Format: <string>
2667 [x86] reliable: mark tsc clocksource as reliable, this
2668 disables clocksource verification at runtime.
2669 Used to enable high-resolution timer mode on older
2670 hardware, and in virtualized environment.
2671
a9913044
RD
2672 turbografx.map[2|3]= [HW,JOY]
2673 TurboGraFX parallel port interface
2674 Format:
2675 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2676 See also Documentation/input/joystick-parport.txt
2677
2678 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2679 See header of drivers/scsi/u14-34f.c.
2680
2681 uart401= [HW,OSS]
2682 Format: <io>,<irq>
2683
2684 uart6850= [HW,OSS]
2685 Format: <io>,<irq>
2686
f86dcc5a
ED
2687 uhash_entries= [KNL,NET]
2688 Set number of hash buckets for UDP/UDP-Lite connections
2689
5f8364b7
AS
2690 uhci-hcd.ignore_oc=
2691 [USB] Ignore overcurrent events (default N).
2692 Some badly-designed motherboards generate lots of
2693 bogus events, for ports that aren't wired to
2694 anything. Set this parameter to avoid log spamming.
2695 Note that genuine overcurrent events won't be
2696 reported either.
2697
e3a61b0a 2698 unknown_nmi_panic
6cececfc 2699 [X86]
e3a61b0a
SA
2700 Set unknown_nmi_panic=1 early on boot.
2701
b5e795f8
AS
2702 usbcore.autosuspend=
2703 [USB] The autosuspend time delay (in seconds) used
2704 for newly-detected USB devices (default 2). This
2705 is the time required before an idle device will be
2706 autosuspended. Devices for which the delay is set
eaafbc3a 2707 to a negative value won't be autosuspended at all.
b5e795f8 2708
fd7c519d
JK
2709 usbcore.usbfs_snoop=
2710 [USB] Set to log all usbfs traffic (default 0 = off).
2711
2712 usbcore.blinkenlights=
2713 [USB] Set to cycle leds on hubs (default 0 = off).
2714
2715 usbcore.old_scheme_first=
2716 [USB] Start with the old device initialization
2717 scheme (default 0 = off).
2718
2719 usbcore.use_both_schemes=
2720 [USB] Try the other device initialization scheme
2721 if the first one fails (default 1 = enabled).
2722
2723 usbcore.initial_descriptor_timeout=
2724 [USB] Specifies timeout for the initial 64-byte
2725 USB_REQ_GET_DESCRIPTOR request in milliseconds
2726 (default 5000 = 5.0 seconds).
2727
1da177e4
LT
2728 usbhid.mousepoll=
2729 [USBHID] The interval which mice are to be polled at.
a9913044 2730
d4f373e5
AS
2731 usb-storage.delay_use=
2732 [UMS] The delay in seconds before a new device is
2733 scanned for Logical Units (default 5).
2734
2735 usb-storage.quirks=
2736 [UMS] A list of quirks entries to supplement or
2737 override the built-in unusual_devs list. List
2738 entries are separated by commas. Each entry has
2739 the form VID:PID:Flags where VID and PID are Vendor
2740 and Product ID values (4-digit hex numbers) and
2741 Flags is a set of characters, each corresponding
2742 to a common usb-storage quirk flag as follows:
c838ea46
AS
2743 a = SANE_SENSE (collect more than 18 bytes
2744 of sense data);
a0bb1081
AS
2745 b = BAD_SENSE (don't collect more than 18
2746 bytes of sense data);
d4f373e5
AS
2747 c = FIX_CAPACITY (decrease the reported
2748 device capacity by one sector);
c838ea46
AS
2749 h = CAPACITY_HEURISTICS (decrease the
2750 reported device capacity by one
2751 sector if the number is odd);
d4f373e5
AS
2752 i = IGNORE_DEVICE (don't bind to this
2753 device);
2754 l = NOT_LOCKABLE (don't try to lock and
2755 unlock ejectable media);
2756 m = MAX_SECTORS_64 (don't transfer more
2757 than 64 sectors = 32 KB at a time);
c838ea46
AS
2758 o = CAPACITY_OK (accept the capacity
2759 reported by the device);
d4f373e5
AS
2760 r = IGNORE_RESIDUE (the device reports
2761 bogus residue values);
2762 s = SINGLE_LUN (the device has only one
2763 Logical Unit);
2764 w = NO_WP_DETECT (don't test whether the
2765 medium is write-protected).
2766 Example: quirks=0419:aaf5:rl,0421:0433:rc
2767
14315592
IC
2768 userpte=
2769 [X86] Flags controlling user PTE allocations.
2770
2771 nohigh = do not allocate PTE pages in
2772 HIGHMEM regardless of setting
2773 of CONFIG_HIGHPTE.
2774
6cececfc 2775 vdso= [X86,SH]
1dbf527c 2776 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2777 vdso=1: enable VDSO (default)
2778 vdso=0: disable VDSO mapping
2779
6cececfc 2780 vdso32= [X86]
af65d648
RM
2781 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2782 vdso32=1: enable 32-bit VDSO (default)
2783 vdso32=0: disable 32-bit VDSO mapping
2784
d080d397
YI
2785 vector= [IA-64,SMP]
2786 vector=percpu: enable percpu vector domain
2787
1da177e4
LT
2788 video= [FB] Frame buffer configuration
2789 See Documentation/fb/modedb.txt.
2790
cd4f0ef7 2791 vga= [BOOT,X86-32] Select a particular video mode
954a8b81 2792 See Documentation/x86/boot.txt and
a9913044 2793 Documentation/svga.txt.
1da177e4
LT
2794 Use vga=ask for menu.
2795 This is actually a boot loader parameter; the value is
2796 passed to the kernel using a special protocol.
2797
a9913044 2798 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2799 size of <nn>. This can be used to increase the
2800 minimum size (128MB on x86). It can also be used to
2801 decrease the size and leave more room for directly
2802 mapped kernel RAM.
2803
585c3047
PO
2804 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2805 Format: <command>
1da177e4 2806
585c3047
PO
2807 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2808 Format: <command>
2809
2810 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2811 Format: <command>
a9913044 2812
9ea9a886
CL
2813 vt.cur_default= [VT] Default cursor shape.
2814 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2815 the parameters of the <Esc>[?A;B;Cc escape sequence;
2816 see VGA-softcursor.txt. Default: 2 = underline.
2817
0cb55ad2
RD
2818 vt.default_blu= [VT]
2819 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2820 Change the default blue palette of the console.
2821 This is a 16-member array composed of values
2822 ranging from 0-255.
2823
2824 vt.default_grn= [VT]
2825 Format: <green0>,<green1>,<green2>,...,<green15>
2826 Change the default green palette of the console.
2827 This is a 16-member array composed of values
2828 ranging from 0-255.
2829
2830 vt.default_red= [VT]
2831 Format: <red0>,<red1>,<red2>,...,<red15>
2832 Change the default red palette of the console.
2833 This is a 16-member array composed of values
2834 ranging from 0-255.
2835
2836 vt.default_utf8=
2837 [VT]
2838 Format=<0|1>
2839 Set system-wide default UTF-8 mode for all tty's.
2840 Default is 1, i.e. UTF-8 mode is enabled for all
2841 newly opened terminals.
2842
f6c06b68
MG
2843 vt.global_cursor_default=
2844 [VT]
2845 Format=<-1|0|1>
2846 Set system-wide default for whether a cursor
2847 is shown on new VTs. Default is -1,
2848 i.e. cursors will be created by default unless
2849 overridden by individual drivers. 0 will hide
2850 cursors, 1 will display them.
2851
1da177e4
LT
2852 waveartist= [HW,OSS]
2853 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2854
1da177e4
LT
2855 wd33c93= [HW,SCSI]
2856 See header of drivers/scsi/wd33c93.c.
2857
2858 wd7000= [HW,SCSI]
2859 See header of drivers/scsi/wd7000.c.
2860
4724ba57
RD
2861 watchdog timers [HW,WDT] For information on watchdog timers,
2862 see Documentation/watchdog/watchdog-parameters.txt
2863 or other driver-specific files in the
2864 Documentation/watchdog/ directory.
1da177e4 2865
0cb55ad2
RD
2866 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2867 default x2apic cluster mode on platforms
2868 supporting x2apic.
2869
bb24c471
JP
2870 x86_mrst_timer= [X86-32,APBT]
2871 Choose timer option for x86 Moorestown MID platform.
2872 Two valid options are apbt timer only and lapic timer
2873 plus one apbt timer for broadcast timer.
2874 x86_mrst_timer=apbt_only | lapic_and_apbt
2875
1da177e4
LT
2876 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2877 xd_geo= See header of drivers/block/xd.c.
2878
2879 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2880 Format:
2881 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2882
a9913044 2883______________________________________________________________________
1da177e4
LT
2884
2885TODO:
2886
2887 Add documentation for ALSA options.
2888 Add more DRM drivers.