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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
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3
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
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20Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
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26This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
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33The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
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37
38 ACPI ACPI support is enabled.
c99c108a 39 AGP AGP (Accelerated Graphics Port) is enabled.
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40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
e7ba176b 43 AVR32 AVR32 architecture is enabled.
1da177e4 44 AX25 Appropriate AX.25 support is enabled.
0ae53640 45 BLACKFIN Blackfin architecture is enabled.
a9913044 46 DRM Direct Rendering Management support is enabled.
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47 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
2521f2c2 51 GCOV GCOV profiling is enabled.
1da177e4 52 HW Appropriate hardware is enabled.
1da177e4 53 IA-64 IA-64 architecture is enabled.
6146f0d5 54 IMA Integrity measurement architecture is enabled.
1da177e4 55 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 56 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
b0f83b28 57 IPV6 IPv6 support is enabled.
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58 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
fef07aae 61 KVM Kernel Virtual Machine support is enabled.
11ef697b 62 LIBATA Libata driver is enabled
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63 LP Printer support is enabled.
64 LOOP Loopback device support is enabled.
65 M68k M68k architecture is enabled.
66 These options have more detailed description inside of
67 Documentation/m68k/kernel-options.txt.
68 MCA MCA bus support is enabled.
69 MDA MDA console support is enabled.
70 MOUSE Appropriate mouse support is enabled.
309e57df 71 MSI Message Signaled Interrupts (PCI).
c8facbb6 72 MTD MTD (Memory Technology Device) support is enabled.
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73 NET Appropriate network support is enabled.
74 NUMA NUMA support is enabled.
734efb46 75 GENERIC_TIME The generic timeofday code is enabled.
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76 NFS Appropriate NFS support is enabled.
77 OSS OSS sound support is enabled.
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78 PV_OPS A paravirtualized kernel is enabled.
79 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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80 PARISC The PA-RISC architecture is enabled.
81 PCI PCI bus support is enabled.
7f785763 82 PCIE PCI Express support is enabled.
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83 PCMCIA The PCMCIA subsystem is enabled.
84 PNP Plug & Play support is enabled.
85 PPC PowerPC architecture is enabled.
86 PPT Parallel port support is enabled.
87 PS2 Appropriate PS/2 support is enabled.
88 RAM RAM disk support is enabled.
89 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
92 Documentation/scsi/.
20510f2f 93 SECURITY Different security models are enabled.
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94 SELINUX SELinux support is enabled.
95 SERIAL Serial support is enabled.
e523d93c 96 SH SuperH architecture is enabled.
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97 SMP The kernel is an SMP kernel.
98 SPARC Sparc architecture is enabled.
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99 SWSUSP Software suspend (hibernation) is enabled.
100 SUSPEND System suspend states are enabled.
f38f1d2a 101 FTRACE Function tracing enabled.
1da177e4 102 TS Appropriate touchscreen support is enabled.
d4f373e5 103 UMS USB Mass Storage support is enabled.
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104 USB USB support is enabled.
105 USBHID USB Human Interface Device support is enabled.
106 V4L Video For Linux support is enabled.
107 VGA The VGA console has been enabled.
108 VT Virtual terminal support is enabled.
109 WDT Watchdog support is enabled.
110 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 111 X86-32 X86-32, aka i386 architecture is enabled.
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112 X86-64 X86-64 architecture is enabled.
113 More X86-64 boot options can be found in
71cced6e 114 Documentation/x86/x86_64/boot-options.txt .
c0115606 115 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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116
117In addition, the following text indicates that the option:
118
119 BUGS= Relates to possible processor bugs on the said processor.
120 KNL Is a kernel start-up parameter.
121 BOOT Is a boot loader parameter.
122
123Parameters denoted with BOOT are actually interpreted by the boot
124loader, and have no meaning to the kernel directly.
125Do not modify the syntax of boot loader parameters without extreme
954a8b81 126need or coordination with <Documentation/x86/boot.txt>.
1da177e4 127
5558870b 128There are also arch-specific kernel-parameters not documented here.
71cced6e 129See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 130
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131Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
132a trailing = on the name of any parameter states that that parameter will
133be entered as an environment variable, whereas its absence indicates that
134it will appear as a kernel argument readable via /proc/cmdline by programs
135running once the system is up.
136
9c4751fd 137The number of kernel parameters is not limited, but the length of the
138complete command line (parameters including spaces etc.) is limited to
139a fixed number of characters. This limit depends on the architecture
140and is between 256 and 4096 characters. It is defined in the file
141./include/asm/setup.h as COMMAND_LINE_SIZE.
142
143
6cececfc 144 acpi= [HW,ACPI,X86]
03d926f8 145 Advanced Configuration and Power Interface
68ca4069 146 Format: { force | off | strict | noirq | rsdt }
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147 force -- enable ACPI if default was off
148 off -- disable ACPI if default was on
149 noirq -- do not use ACPI for IRQ routing
a9913044 150 strict -- Be less tolerant of platforms that are not
1da177e4 151 strictly ACPI specification compliant.
237889bf 152 rsdt -- prefer RSDT over (default) XSDT
1da177e4 153
53471121 154 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 155
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156 acpi_apic_instance= [ACPI, IOAPIC]
157 Format: <int>
158 2: use 2nd APIC table, if available
159 1,0: use 1st APIC table
4e381a4f 160 default: 0
a1fdcc0d 161
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162 acpi_backlight= [HW,ACPI]
163 acpi_backlight=vendor
164 acpi_backlight=video
165 If set to vendor, prefer vendor specific driver
166 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
167 of the ACPI video.ko driver.
168
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169 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
170 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 171 Format: <int>
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172 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
173 debug output. Bits in debug_layer correspond to a
174 _COMPONENT in an ACPI source file, e.g.,
175 #define _COMPONENT ACPI_PCI_COMPONENT
176 Bits in debug_level correspond to a level in
177 ACPI_DEBUG_PRINT statements, e.g.,
178 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
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179 The debug_level mask defaults to "info". See
180 Documentation/acpi/debug.txt for more information about
181 debug layers and levels.
a0d84a92 182
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183 Enable processor driver info messages:
184 acpi.debug_layer=0x20000000
185 Enable PCI/PCI interrupt routing info messages:
186 acpi.debug_layer=0x400000
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187 Enable AML "Debug" output, i.e., stores to the Debug
188 object while interpreting AML:
189 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
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190 Enable all messages related to ACPI hardware:
191 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
192
193 Some values produce so much output that the system is
194 unusable. The "log_buf_len" parameter may be useful
195 if you need to capture more output.
f989106c 196
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197 acpi_display_output= [HW,ACPI]
198 acpi_display_output=vendor
199 acpi_display_output=video
200 See above.
201
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202 acpi_early_pdc_eval [HW,ACPI] Evaluate processor _PDC methods
203 early. Needed on some platforms to properly
204 initialize the EC.
205
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206 acpi_irq_balance [HW,ACPI]
207 ACPI will balance active IRQs
208 default in APIC mode
209
210 acpi_irq_nobalance [HW,ACPI]
211 ACPI will not move active IRQs (default)
212 default in PIC mode
213
214 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
215 Format: <irq>,<irq>...
216
217 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
218 use by PCI
219 Format: <irq>,<irq>...
220
221 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
222
223 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
224 Format: To spoof as Windows 98: ="Microsoft Windows"
225
226 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
227 acpi_osi="string1" # add string1 -- only one string
228 acpi_osi="!string2" # remove built-in string2
229 acpi_osi= # disable all strings
230
6cececfc 231 acpi_pm_good [X86]
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232 Override the pmtimer bug detection: force the kernel
233 to assume that this machine's pmtimer latches its value
234 and always returns good values.
235
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236 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
237 Format: { level | edge | high | low }
238
239 acpi_serialize [HW,ACPI] force serialization of AML methods
240
241 acpi_skip_timer_override [HW,ACPI]
242 Recognize and ignore IRQ0/pin2 Interrupt Override.
243 For broken nForce2 BIOS resulting in XT-PIC timer.
244
245 acpi_sleep= [HW,ACPI] Sleep options
246 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
d7f0eea9 247 old_ordering, s4_nonvs, sci_force_enable }
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248 See Documentation/power/video.txt for information on
249 s3_bios and s3_mode.
250 s3_beep is for debugging; it makes the PC's speaker beep
251 as soon as the kernel's real-mode entry point is called.
252 s4_nohwsig prevents ACPI hardware signature from being
253 used during resume from hibernation.
254 old_ordering causes the ACPI 1.0 ordering of the _PTS
255 control method, with respect to putting devices into
256 low power states, to be enforced (the ACPI 2.0 ordering
257 of _PTS is used by default).
258 s4_nonvs prevents the kernel from saving/restoring the
259 ACPI NVS memory during hibernation.
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260 sci_force_enable causes the kernel to set SCI_EN directly
261 on resume from S1/S3 (which is against the ACPI spec,
262 but some broken systems don't work without it).
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263
264 acpi_use_timer_override [HW,ACPI]
265 Use timer override. For some broken Nvidia NF5 boards
266 that require a timer override, but don't have HPET
267
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268 acpi_enforce_resources= [ACPI]
269 { strict | lax | no }
270 Check for resource conflicts between native drivers
271 and ACPI OperationRegions (SystemIO and SystemMemory
272 only). IO ports and memory declared in ACPI might be
273 used by the ACPI subsystem in arbitrary AML code and
274 can interfere with legacy drivers.
275 strict (default): access to resources claimed by ACPI
276 is denied; legacy drivers trying to access reserved
277 resources will fail to bind to device using them.
278 lax: access to resources claimed by ACPI is allowed;
279 legacy drivers trying to access reserved resources
280 will bind successfully but a warning message is logged.
281 no: ACPI OperationRegions are not marked as reserved,
282 no further checks are performed.
283
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284 ad1848= [HW,OSS]
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
286
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287 add_efi_memmap [EFI; X86] Include EFI memory map in
288 kernel's map of available physical RAM.
289
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290 advansys= [HW,SCSI]
291 See header of drivers/scsi/advansys.c.
292
293 advwdt= [HW,WDT] Advantech WDT
294 Format: <iostart>,<iostop>
295
296 aedsp16= [HW,OSS] Audio Excel DSP 16
297 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
298 See also header of sound/oss/aedsp16.c.
a9913044 299
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300 agp= [AGP]
301 { off | try_unsupported }
302 off: disable AGP support
303 try_unsupported: try to drive unsupported chipsets
304 (may crash computer or cause data corruption)
305
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306 aha152x= [HW,SCSI]
307 See Documentation/scsi/aha152x.txt.
308
309 aha1542= [HW,SCSI]
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
311
312 aic7xxx= [HW,SCSI]
313 See Documentation/scsi/aic7xxx.txt.
314
315 aic79xx= [HW,SCSI]
316 See Documentation/scsi/aic79xx.txt.
317
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318 alignment= [KNL,ARM]
319 Allow the default userspace alignment fault handler
320 behaviour to be specified. Bit 0 enables warnings,
321 bit 1 enables fixups, and bit 2 sends a segfault.
322
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323 amd_iommu= [HW,X86-84]
324 Pass parameters to the AMD IOMMU driver in the system.
325 Possible values are:
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326 isolate - enable device isolation (each device, as far
327 as possible, will get its own protection
3ce1f93c 328 domain) [default]
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329 share - put every device behind one IOMMU into the
330 same protection domain
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331 fullflush - enable flushing of IO/TLB entries when
332 they are unmapped. Otherwise they are
333 flushed before they will be reused, which
334 is a lot of faster
335
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336 amijoy.map= [HW,JOY] Amiga joystick support
337 Map of devices attached to JOY0DAT and JOY1DAT
338 Format: <a>,<b>
339 See also Documentation/kernel/input/joystick.txt
340
341 analog.map= [HW,JOY] Analog joystick and gamepad support
342 Specifies type or capabilities of an analog joystick
343 connected to one of 16 gameports
344 Format: <type1>,<type2>,..<type16>
345
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346 apc= [HW,SPARC]
347 Power management functions (SPARCstation-4/5 + deriv.)
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348 Format: noidle
349 Disable APC CPU standby support. SPARCstation-Fox does
350 not play well with APC CPU idle - disable it if you have
351 APC and your system crashes randomly.
352
ca1eda2d 353 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
c8facbb6 354 Change the output verbosity whilst booting
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355 Format: { quiet (default) | verbose | debug }
356 Change the amount of debugging information output
357 when initialising the APIC and IO-APIC components.
a9913044 358
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359 autoconf= [IPV6]
360 See Documentation/networking/ipv6.txt.
361
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362 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
363 Limit apic dumping. The parameter defines the maximal
364 number of local apics being dumped. Also it is possible
365 to set it to "all" by meaning -- no limit here.
366 Format: { 1 (default) | 2 | ... | all }.
367 The parameter valid if only apic=debug or
368 apic=verbose is specified.
369 Example: apic=debug show_lapic=all
370
1da177e4 371 apm= [APM] Advanced Power Management
71f77055 372 See header of arch/x86/kernel/apm_32.c.
1da177e4 373
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374 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
375 Format: <io>,<irq>,<nodeID>
376
377 ataflop= [HW,M68k]
378
379 atarimouse= [HW,MOUSE] Atari Mouse
380
381 atascsi= [HW,SCSI] Atari SCSI
382
383 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
384 EzKey and similar keyboards
385
386 atkbd.reset= [HW] Reset keyboard during initialization
387
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388 atkbd.set= [HW] Select keyboard code set
389 Format: <int> (2 = AT (default), 3 = PS/2)
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390
391 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
392 keyboards
393
394 atkbd.softraw= [HW] Choose between synthetic and real raw mode
395 Format: <bool> (0 = real, 1 = synthetic (default))
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396
397 atkbd.softrepeat= [HW]
398 Use software keyboard repeat
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399
400 autotest [IA64]
401
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402 baycom_epp= [HW,AX25]
403 Format: <io>,<mode>
a9913044 404
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405 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
406 Format: <io>,<mode>
407 See header of drivers/net/hamradio/baycom_par.c.
408
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409 baycom_ser_fdx= [HW,AX25]
410 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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411 Format: <io>,<irq>,<mode>[,<baud>]
412 See header of drivers/net/hamradio/baycom_ser_fdx.c.
413
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414 baycom_ser_hdx= [HW,AX25]
415 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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416 Format: <io>,<irq>,<mode>
417 See header of drivers/net/hamradio/baycom_ser_hdx.c.
418
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419 boot_delay= Milliseconds to delay each printk during boot.
420 Values larger than 10 seconds (10000) are changed to
421 no delay (0).
422 Format: integer
423
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424 bootmem_debug [KNL] Enable bootmem allocator debug messages.
425
1da177e4 426 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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427 bttv.radio= Most important insmod options are available as
428 kernel args too.
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429 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
430 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
431
432 BusLogic= [HW,SCSI]
433 See drivers/scsi/BusLogic.c, comment before function
434 BusLogic_ParseDriverOptions().
435
436 c101= [NET] Moxa C101 synchronous serial card
437
cd4f0ef7 438 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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439 Sometimes CPU hardware bugs make them report the cache
440 size incorrectly. The kernel will attempt work arounds
441 to fix known problems, but for some CPUs it is not
442 possible to determine what the correct size should be.
443 This option provides an override for these situations.
444
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445 capability.disable=
446 [SECURITY] Disable capabilities. This would normally
447 be used only if an alternative security model is to be
448 configured. Potentially dangerous and should only be
449 used if you are entirely sure of the consequences.
450
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451 ccw_timeout_log [S390]
452 See Documentation/s390/CommonIO for details.
1da177e4 453
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454 cgroup_disable= [KNL] Disable a particular controller
455 Format: {name of the controller(s) to disable}
456 {Currently supported controllers - "memory"}
457
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458 checkreqprot [SELINUX] Set initial checkreqprot flag value.
459 Format: { "0" | "1" }
460 See security/selinux/Kconfig help text.
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461 0 -- check protection applied by kernel (includes
462 any implied execute protection).
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463 1 -- check protection requested by application.
464 Default value is set via a kernel config option.
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465 Value can be changed at runtime via
466 /selinux/checkreqprot.
467
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468 cio_ignore= [S390]
469 See Documentation/s390/CommonIO for details.
470
cd4f0ef7 471 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 472 [Deprecated]
3f6dee9b 473 Forces specified clocksource (if available) to be used
734efb46 474 when calculating gettimeofday(). If specified
3f6dee9b 475 clocksource is not available, it defaults to PIT.
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476 Format: { pit | tsc | cyclone | pmtmr }
477
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478 clocksource= [GENERIC_TIME] Override the default clocksource
479 Format: <string>
480 Override the default clocksource and use the clocksource
481 with the name specified.
482 Some clocksource names to choose from, depending on
483 the platform:
484 [all] jiffies (this is the base, fallback clocksource)
485 [ACPI] acpi_pm
486 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
487 pxa_timer,timer3,32k_counter,timer0_1
488 [AVR32] avr32
cd4f0ef7 489 [X86-32] pit,hpet,tsc,vmi-timer;
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490 scx200_hrt on Geode; cyclone on IBM x440
491 [MIPS] MIPS
492 [PARISC] cr16
493 [S390] tod
494 [SH] SuperH
495 [SPARC64] tick
496 [X86-64] hpet,tsc
497
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498 clearcpuid=BITNUM [X86]
499 Disable CPUID feature X for the kernel. See
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500 arch/x86/include/asm/cpufeature.h for the valid bit
501 numbers. Note the Linux specific bits are not necessarily
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502 stable over kernel options, but the vendor specific
503 ones should be.
504 Also note that user programs calling CPUID directly
505 or using the feature without checking anything
506 will still see it. This just prevents it from
507 being used by the kernel or shown in /proc/cpuinfo.
508 Also note the kernel might malfunction if you disable
509 some critical bits.
510
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511 cmo_free_hint= [PPC] Format: { yes | no }
512 Specify whether pages are marked as being inactive
513 when they are freed. This is used in CMO environments
514 to determine OS memory pressure for page stealing by
515 a hypervisor.
516 Default: yes
517
6cececfc 518 code_bytes [X86] How many bytes of object code to print
a25bd949 519 in an oops report.
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520 Range: 0 - 8192
521 Default: 64
522
1da177e4 523 com20020= [HW,NET] ARCnet - COM20020 chipset
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524 Format:
525 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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526
527 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
528 Format: <io>[,<irq>]
529
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530 com90xx= [HW,NET]
531 ARCnet - COM90xx chipset (memory-mapped buffers)
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532 Format: <io>[,<irq>[,<memstart>]]
533
534 condev= [HW,S390] console device
535 conmode=
a9913044 536
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537 console= [KNL] Output console device and options.
538
539 tty<n> Use the virtual console device <n>.
540
541 ttyS<n>[,options]
f1a1c2dc 542 ttyUSB0[,options]
1da177e4 543 Use the specified serial port. The options are of
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RD
544 the form "bbbbpnf", where "bbbb" is the baud rate,
545 "p" is parity ("n", "o", or "e"), "n" is number of
546 bits, and "f" is flow control ("r" for RTS or
547 omit it). Default is "9600n8".
548
549 See Documentation/serial-console.txt for more
550 information. See
551 Documentation/networking/netconsole.txt for an
552 alternative.
1da177e4 553
18a8bd94
YL
554 uart[8250],io,<addr>[,options]
555 uart[8250],mmio,<addr>[,options]
1da177e4
LT
556 Start an early, polled-mode console on the 8250/16550
557 UART at the specified I/O port or MMIO address,
558 switching to the matching ttyS device later. The
559 options are the same as for ttyS, above.
560
f7511d5f
ST
561 If the device connected to the port is not a TTY but a braille
562 device, prepend "brl," before the device type, for instance
563 console=brl,ttyS0
564 For now, only VisioBraille is supported.
565
f324edc8
DM
566 consoleblank= [KNL] The console blank (screen saver) timeout in
567 seconds. Defaults to 10*60 = 10mins. A value of 0
568 disables the blank timer.
569
4cb0e11b
HK
570 coredump_filter=
571 [KNL] Change the default value for
572 /proc/<pid>/coredump_filter.
573 See also Documentation/filesystems/proc.txt.
574
1da177e4 575 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
576 Format:
577 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 578
dc009d92
EB
579 crashkernel=nn[KMG]@ss[KMG]
580 [KNL] Reserve a chunk of physical memory to
581 hold a kernel to switch to with kexec on panic.
582
fb391599
BW
583 crashkernel=range1:size1[,range2:size2,...][@offset]
584 [KNL] Same as above, but depends on the memory
585 in the running system. The syntax of range is
586 start-[end] where start and end are both
587 a memory unit (amount[KMG]). See also
588 Documentation/kdump/kdump.txt for a example.
589
1da177e4
LT
590 cs89x0_dma= [HW,NET]
591 Format: <dma>
592
593 cs89x0_media= [HW,NET]
594 Format: { rj45 | aui | bnc }
a9913044 595
a9913044 596 dasd= [HW,NET]
1da177e4
LT
597 See header of drivers/s390/block/dasd_devmap.c.
598
599 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
600 (one device per port)
601 Format: <port#>,<type>
602 See also Documentation/input/joystick-parport.txt
603
604 debug [KNL] Enable kernel debugging (events log level).
605
cae2ed9a
IM
606 debug_locks_verbose=
607 [KNL] verbose self-tests
608 Format=<0|1>
609 Print debugging info while doing the locking API
610 self-tests.
611 We default to 0 (no extra messages), setting it to
612 1 will print _a lot_ more information - normally
613 only useful to kernel developers.
614
3ac7fe5a
TG
615 debug_objects [KNL] Enable object debugging
616
3e8ebb5c
KM
617 no_debug_objects
618 [KNL] Disable object debugging
619
d3af01f1
TG
620 debugpat [X86] Enable PAT debugging
621
2d27a966 622 decnet.addr= [HW,NET]
1da177e4
LT
623 Format: <area>[,<node>]
624 See also Documentation/networking/decnet.txt.
625
0cb55ad2
RD
626 default_hugepagesz=
627 [same as hugepagesz=] The size of the default
628 HugeTLB page size. This is the size represented by
629 the legacy /proc/ hugepages APIs, used for SHM, and
630 default size when mounting hugetlbfs filesystems.
631 Defaults to the default architecture's huge page size
632 if not specified.
55ff9780 633
1da177e4
LT
634 dhash_entries= [KNL]
635 Set number of hash buckets for dentry cache.
a9913044 636
1da177e4
LT
637 digi= [HW,SERIAL]
638 IO parameters + enable/disable command.
639
640 digiepca= [HW,SERIAL]
641 See drivers/char/README.epca and
31c00fc1 642 Documentation/serial/digiepca.txt.
1da177e4 643
b0f83b28
BH
644 disable= [IPV6]
645 See Documentation/networking/ipv6.txt.
646
647 disable_ipv6= [IPV6]
648 See Documentation/networking/ipv6.txt.
649
95ffa243 650 disable_mtrr_cleanup [X86]
95ffa243
YL
651 The kernel tries to adjust MTRR layout from continuous
652 to discrete, to make X server driver able to add WB
0cb55ad2 653 entry later. This parameter disables that.
95ffa243 654
093af8d7 655 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
656 By default the kernel will trim any uncacheable
657 memory out of your available memory pool based on
658 MTRR settings. This parameter disables that behavior,
659 possibly causing your machine to run very slowly.
660
6cececfc 661 disable_timer_pin_1 [X86]
0cb55ad2
RD
662 Disable PIN 1 of APIC timer
663 Can be useful to work around chipset bugs.
664
1da177e4
LT
665 dmasound= [HW,OSS] Sound subsystem buffers
666
0cb55ad2
RD
667 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
668 this option disables the debugging code at boot.
669
670 dma_debug_entries=<number>
671 This option allows to tune the number of preallocated
672 entries for DMA-API debugging code. One entry is
673 required per DMA-API allocation. Use this if the
674 DMA-API debugging code disables itself because the
675 architectural default is too low.
676
1745de5e
JR
677 dma_debug_driver=<driver_name>
678 With this option the DMA-API debugging driver
679 filter feature can be enabled at boot time. Just
680 pass the driver to filter for as the parameter.
681 The filter can be disabled or changed to another
682 driver later using sysfs.
683
1da177e4
LT
684 dscc4.setup= [NET]
685
686 dtc3181e= [HW,SCSI]
687
0cb55ad2
RD
688 dynamic_printk Enables pr_debug()/dev_dbg() calls if
689 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
690 These can also be switched on/off via
691 <debugfs>/dynamic_printk/modules
692
693 earlycon= [KNL] Output early console device and options.
694 uart[8250],io,<addr>[,options]
695 uart[8250],mmio,<addr>[,options]
696 Start an early, polled-mode console on the 8250/16550
697 UART at the specified I/O port or MMIO address.
698 The options are the same as for ttyS, above.
699
6cececfc 700 earlyprintk= [X86,SH,BLACKFIN]
1da177e4
LT
701 earlyprintk=vga
702 earlyprintk=serial[,ttySn[,baudrate]]
ea3acb19 703 earlyprintk=ttySn[,baudrate]
9780bc41 704 earlyprintk=dbgp[debugController#]
1da177e4 705
a9913044 706 Append ",keep" to not disable it when the real console
1da177e4
LT
707 takes over.
708
5c05917e 709 Only vga or serial or usb debug port at a time.
1da177e4
LT
710
711 Currently only ttyS0 and ttyS1 are supported.
712
713 Interaction with the standard serial driver is not
714 very good.
715
716 The VGA output is eventually overwritten by the real
717 console.
718
719 eata= [HW,SCSI]
720
1da177e4 721 edd= [EDD]
8c4dd606 722 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 723
1da177e4
LT
724 eisa_irq_edge= [PARISC,HW]
725 See header of drivers/parisc/eisa.c.
726
cd4f0ef7 727 elanfreq= [X86-32]
1da177e4 728 See comment before function elanfreq_setup() in
71f77055 729 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
730
731 elevator= [IOSCHED]
16ab3adf 732 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
733 See Documentation/block/as-iosched.txt and
734 Documentation/block/deadline-iosched.txt for details.
735
6cececfc 736 elfcorehdr= [IA64,PPC,SH,X86]
a9913044 737 Specifies physical address of start of kernel core
aac04b32
VG
738 image elf header. Generally kexec loader will
739 pass this option to capture kernel.
740 See Documentation/kdump/kdump.txt for details.
1da177e4 741
0cb55ad2
RD
742 enable_mtrr_cleanup [X86]
743 The kernel tries to adjust MTRR layout from continuous
744 to discrete, to make X server driver able to add WB
745 entry later. This parameter enables that.
746
ca1eda2d 747 enable_timer_pin_1 [X86]
0cb55ad2
RD
748 Enable PIN 1 of APIC timer
749 Can be useful to work around chipset bugs
750 (in particular on some ATI chipsets).
751 The kernel tries to set a reasonable default.
752
1da177e4
LT
753 enforcing [SELINUX] Set initial enforcing status.
754 Format: {"0" | "1"}
755 See security/selinux/Kconfig help text.
756 0 -- permissive (log only, no denials).
757 1 -- enforcing (deny and log).
758 Default value is 0.
759 Value can be changed at runtime via /selinux/enforce.
760
1da177e4
LT
761 ether= [HW,NET] Ethernet cards parameters
762 This option is obsoleted by the "netdev=" option, which
763 has equivalent usage. See its documentation for details.
764
765 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
766 Format: <io>[,<irq>]
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
795 ftrace_dump_on_oops
2af15d6a
SR
796 [FTRACE] will dump the trace buffers on oops.
797
798 ftrace_filter=[function-list]
799 [FTRACE] Limit the functions traced by the function
800 tracer at boot up. function-list is a comma separated
801 list of functions. This list can be changed at run
802 time by the set_ftrace_filter file in the debugfs
803 tracing directory.
804
805 ftrace_notrace=[function-list]
806 [FTRACE] Do not trace the functions specified in
807 function-list. This list can be changed at run time
808 by the set_ftrace_notrace file in the debugfs
809 tracing directory.
d9e54076 810
369bc18f
SA
811 ftrace_graph_filter=[function-list]
812 [FTRACE] Limit the top level callers functions traced
813 by the function graph tracer at boot up.
814 function-list is a comma separated list of functions
815 that can be changed at run time by the
816 set_graph_function file in the debugfs tracing directory.
817
1da177e4
LT
818 gamecon.map[2|3]=
819 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
820 support via parallel port (up to 5 devices per port)
821 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
822 See also Documentation/input/joystick-parport.txt
823
824 gamma= [HW,DRM]
825
aaf23042
YL
826 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
827 Format: off | on
828 default: on
829
2521f2c2
PO
830 gcov_persist= [GCOV] When non-zero (default), profiling data for
831 kernel modules is saved and remains accessible via
832 debugfs, even when the module is unloaded/reloaded.
833 When zero, profiling data is discarded and associated
834 debugfs files are removed at module unload time.
835
1da177e4
LT
836 gdth= [HW,SCSI]
837 See header of drivers/scsi/gdth.c.
838
839 gpt [EFI] Forces disk with valid GPT signature but
840 invalid Protective MBR to be treated as GPT.
841
1da177e4
LT
842 gvp11= [HW,SCSI]
843
844 hashdist= [KNL,NUMA] Large hashes allocated during boot
845 are distributed across NUMA nodes. Defaults on
429aa0fc 846 for 64bit NUMA, off otherwise.
a9913044 847 Format: 0 | 1 (for off | on)
1da177e4
LT
848
849 hcl= [IA-64] SGI's Hardware Graph compatibility layer
850
851 hd= [EIDE] (E)IDE hard drive subsystem geometry
852 Format: <cyl>,<head>,<sect>
853
1da177e4
LT
854 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
855 size of <nn>. This works even on boxes that have no
856 highmem otherwise. This also works to reduce highmem
857 size on bigger boxes.
858
54cdfdb4
TG
859 highres= [KNL] Enable/disable high resolution timer mode.
860 Valid parameters: "on", "off"
861 Default: "on"
862
1da177e4
LT
863 hisax= [HW,ISDN]
864 See Documentation/isdn/README.HiSax.
865
0cb55ad2
RD
866 hlt [BUGS=ARM,SH]
867
868 hpet= [X86-32,HPET] option to control HPET usage
869 Format: { enable (default) | disable | force |
870 verbose }
871 disable: disable HPET and use PIT instead
872 force: allow force enabled of undocumented chips (ICH4,
873 VIA, nVidia)
874 verbose: show contents of HPET registers during setup
875
b4718e62
AK
876 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
877 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
878 On x86-64 and powerpc, this option can be specified
879 multiple times interleaved with hugepages= to reserve
880 huge pages of different sizes. Valid pages sizes on
881 x86-64 are 2M (when the CPU supports "pse") and 1G
882 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
883 Note that 1GB pages can only be allocated at boot time
884 using hugepages= and not freed afterwards.
6902aa84 885
555d61d6
HB
886 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
887 terminal devices. Valid values: 0..8
431429ff
HB
888 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
889 If specified, z/VM IUCV HVC accepts connections
890 from listed z/VM user IDs only.
cef7125d 891
3a853fb9 892 i2c_bus= [HW] Override the default board specific I2C bus speed
7954763b
JN
893 or register an additional I2C bus that is not
894 registered from board initialization code.
3a853fb9
JN
895 Format:
896 <bus_id>,<clkrate>
897
36d95739 898 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 899 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
900 i8042.dumbkbd [HW] Pretend that controller can only read data from
901 keyboard and cannot control its state
1da177e4
LT
902 (Don't attempt to blink the leds)
903 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 904 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
905 i8042.noloop [HW] Disable the AUX Loopback command while probing
906 for the AUX port
1da177e4
LT
907 i8042.nomux [HW] Don't check presence of an active multiplexing
908 controller
909 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
910 controllers
911 i8042.panicblink=
912 [HW] Frequency with which keyboard LEDs should blink
913 when kernel panics (default is 0.5 sec)
914 i8042.reset [HW] Reset the controller during init and cleanup
915 i8042.unlock [HW] Unlock (ignore) the keylock
916
917 i810= [HW,DRM]
918
e70c9d5e
DT
919 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
920 indicates that the driver is running on unsupported
921 hardware.
1da177e4
LT
922 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
923 does not match list of supported models.
924 i8k.power_status
925 [HW] Report power status in /proc/i8k
926 (disabled by default)
927 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
928 capability is set.
929
930 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
931 See Documentation/mca.txt.
932
933 icn= [HW,ISDN]
934 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
935
0af80c04
DF
936 ide-core.nodma= [HW] (E)IDE subsystem
937 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
075affcb
BZ
938 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
939 .cdrom .chs .ignore_cable are additional options
1c10e938 940 See Documentation/ide/ide.txt.
1da177e4 941
0cb55ad2
RD
942 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
943 Claim all unknown PCI IDE storage controllers.
944
f039b754 945 idle= [X86]
ada9cfdd
RD
946 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
947 Poll forces a polling idle loop that can slightly
948 improve the performance of waking up a idle CPU, but
949 will use a lot of power and make the system run hot.
950 Not recommended.
951 idle=mwait: On systems which support MONITOR/MWAIT but
952 the kernel chose to not use it because it doesn't save
953 as much power as a normal idle loop, use the
954 MONITOR/MWAIT idle loop anyways. Performance should be
955 the same as idle=poll.
956 idle=halt: Halt is forced to be used for CPU idle.
c1e3b377 957 In such case C2/C3 won't be used again.
ada9cfdd 958 idle=nomwait: Disable mwait for CPU C-states
a9913044 959
79290822
IM
960 ignore_loglevel [KNL]
961 Ignore loglevel setting - this will print /all/
962 kernel messages to the console. Useful for debugging.
963
1da177e4
LT
964 ihash_entries= [KNL]
965 Set number of hash buckets for inode cache.
966
3323eec9
MZ
967 ima_audit= [IMA]
968 Format: { "0" | "1" }
969 0 -- integrity auditing messages. (Default)
970 1 -- enable informational integrity auditing messages.
971
972 ima_hash= [IMA]
a9ed83a5 973 Format: { "sha1" | "md5" }
3323eec9
MZ
974 default: "sha1"
975
5789ba3b
EP
976 ima_tcb [IMA]
977 Load a policy which meets the needs of the Trusted
978 Computing Base. This means IMA will measure all
979 programs exec'd, files mmap'd for exec, and all files
980 opened for read by uid=0.
981
1da177e4
LT
982 in2000= [HW,SCSI]
983 See header of drivers/scsi/in2000.c.
984
985 init= [KNL]
986 Format: <full_path>
987 Run specified binary instead of /sbin/init as init
988 process.
989
990 initcall_debug [KNL] Trace initcalls as they are executed. Useful
991 for working out where the kernel is dying during
992 startup.
993
994 initrd= [BOOT] Specify the location of the initial ramdisk
995
996 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
997 Format: <irq>
998
ba395927 999 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
0cd5c3c8
KM
1000 on
1001 Enable intel iommu driver.
ba395927
KA
1002 off
1003 Disable intel iommu driver.
1004 igfx_off [Default Off]
1005 By default, gfx is mapped as normal device. If a gfx
1006 device has a dedicated DMAR unit, the DMAR unit is
1007 bypassed by not enabling DMAR with this option. In
1008 this case, gfx device will use physical address for
1009 DMA.
7d3b03ce
KA
1010 forcedac [x86_64]
1011 With this option iommu will not optimize to look
1012 for io virtual address below 32 bit forcing dual
1013 address cycle on pci bus for cards supporting greater
1014 than 32 bit addressing. The default is to look
1015 for translation below 32 bit and if not available
1016 then look in the higher range.
5e0d2a6f 1017 strict [Default Off]
1018 With this option on every unmap_single operation will
1019 result in a hardware IOTLB flush operation as opposed
1020 to batching them for performance.
ba395927 1021
0cb55ad2
RD
1022 inttest= [IA64]
1023
1024 iomem= Disable strict checking of access to MMIO memory
1025 strict regions from userspace.
1026 relaxed
1027
1028 iommu= [x86]
1029 off
1030 force
1031 noforce
1032 biomerge
1033 panic
1034 nopanic
1035 merge
1036 nomerge
1037 forcesac
1038 soft
4ed0d3e6 1039 pt [x86, IA64]
0cb55ad2
RD
1040
1041 io7= [HW] IO7 for Marvel based alpha systems
1042 See comment before marvel_specify_io7 in
1043 arch/alpha/kernel/core_marvel.c.
1044
6cececfc 1045 io_delay= [X86] I/O delay method
6e7c4025
IM
1046 0x80
1047 Standard port 0x80 based delay
1048 0xed
1049 Alternate port 0xed based delay (needed on some systems)
b02aae9c 1050 udelay
6e7c4025
IM
1051 Simple two microseconds delay
1052 none
1053 No delay
b02aae9c 1054
1da177e4 1055 ip= [IP_PNP]
dc7a0816 1056 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1057
1058 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
1059 See comment before ip2_setup() in
1060 drivers/char/ip2/ip2base.c.
1da177e4
LT
1061
1062 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1063 See header of drivers/scsi/ips.c.
1064
200803df
AC
1065 irqfixup [HW]
1066 When an interrupt is not handled search all handlers
1067 for it. Intended to get systems with badly broken
1068 firmware running.
1069
1070 irqpoll [HW]
1071 When an interrupt is not handled search all handlers
1072 for it. Also check all handlers each timer
1073 interrupt. Intended to get systems with badly broken
1074 firmware running.
1075
1da177e4 1076 isapnp= [ISAPNP]
a9913044 1077 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
1078
1079 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
1080 Format:
1081 <cpu number>,...,<cpu number>
1082 or
b225d44e
LZ
1083 <cpu number>-<cpu number>
1084 (must be a positive range in ascending order)
22f2e280
DF
1085 or a mixture
1086 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 1087
1da177e4
LT
1088 This option can be used to specify one or more CPUs
1089 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
1090 algorithms. You can move a process onto or off an
1091 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
1092 <cpu number> begins at 0 and the maximum value is
1093 "number of CPUs in system - 1".
1094
1095 This option is the preferred way to isolate CPUs. The
a9913044
RD
1096 alternative -- manually setting the CPU mask of all
1097 tasks in the system -- can cause problems and
1098 suboptimal load balancer performance.
1da177e4 1099
a9913044 1100 iucv= [HW,NET]
1da177e4
LT
1101
1102 js= [HW,JOY] Analog joystick
1103 See Documentation/input/joystick.txt.
1104
0cb55ad2
RD
1105 keepinitrd [HW,ARM]
1106
6cececfc 1107 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
ed7ed365
MG
1108 specifies the amount of memory usable by the kernel
1109 for non-movable allocations. The requested amount is
1110 spread evenly throughout all nodes in the system. The
1111 remaining memory in each node is used for Movable
1112 pages. In the event, a node is too small to have both
1113 kernelcore and Movable pages, kernelcore pages will
1114 take priority and other nodes will have a larger number
1115 of kernelcore pages. The Movable zone is used for the
1116 allocation of pages that may be reclaimed or moved
1117 by the page migration subsystem. This means that
1118 HugeTLB pages may not be allocated from this zone.
1119 Note that allocations like PTEs-from-HighMem still
1120 use the HighMem zone if it exists, and the Normal
1121 zone if it does not.
1122
6cdf6e06
JW
1123 kgdboc= [HW] kgdb over consoles.
1124 Requires a tty driver that supports console polling.
19f59460 1125 (only serial supported for now)
6cdf6e06
JW
1126 Format: <serial_device>[,baud]
1127
9bed90c6
FF
1128 kmac= [MIPS] korina ethernet MAC address.
1129 Configure the RouterBoard 532 series on-chip
1130 Ethernet adapter MAC address.
1131
04f70336
CM
1132 kmemleak= [KNL] Boot-time kmemleak enable/disable
1133 Valid arguments: on, off
1134 Default: on
1135
6cececfc 1136 kstack=N [X86] Print N words from the kernel stack
0cb55ad2
RD
1137 in oops dumps.
1138
fef07aae
AP
1139 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1140 Default is 0 (don't ignore, but inject #GP)
1141
1142 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1143 Default is 1 (enabled)
1144
1145 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1146 Default is 0 (off)
1147
1148 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1149 for all guests.
1150 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1151
1152 kvm-intel.bypass_guest_pf=
1153 [KVM,Intel] Disables bypassing of guest page faults
1154 on Intel chips. Default is 1 (enabled)
1155
1156 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1157 (virtualized MMU) support on capable Intel chips.
1158 Default is 1 (enabled)
1159
1160 kvm-intel.emulate_invalid_guest_state=
1161 [KVM,Intel] Enable emulation of invalid guest states
1162 Default is 0 (disabled)
1163
1164 kvm-intel.flexpriority=
1165 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1166 Default is 1 (enabled)
1167
1168 kvm-intel.unrestricted_guest=
1169 [KVM,Intel] Disable unrestricted guest feature
1170 (virtualized real and unpaged mode) on capable
1171 Intel chips. Default is 1 (enabled)
1172
1173 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1174 feature (tagged TLBs) on capable Intel chips.
1175 Default is 1 (enabled)
1176
1da177e4
LT
1177 l2cr= [PPC]
1178
a78bfbfc
RB
1179 l3cr= [PPC]
1180
cd4f0ef7 1181 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1182 disabled it.
1da177e4 1183
6cececfc 1184 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
ada9cfdd 1185 in C2 power state.
e585bef8 1186
fcb71f6f
FC
1187 libata.dma= [LIBATA] DMA control
1188 libata.dma=0 Disable all PATA and SATA DMA
1189 libata.dma=1 PATA and SATA Disk DMA only
1190 libata.dma=2 ATAPI (CDROM) DMA only
1191 libata.dma=4 Compact Flash DMA only
1192 Combinations also work, so libata.dma=3 enables DMA
1193 for disks and CDROMs, but not CFs.
20308871
MP
1194
1195 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1196 libata.ignore_hpa=0 keep BIOS limits (default)
1197 libata.ignore_hpa=1 ignore limits, using full disk
fcb71f6f 1198
78e70c23
DJ
1199 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1200 when set.
1201 Format: <int>
1202
33267325
TH
1203 libata.force= [LIBATA] Force configurations. The format is comma
1204 separated list of "[ID:]VAL" where ID is
1205 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1206 matching port, link or device. Basically, it matches
1207 the ATA ID string printed on console by libata. If
1208 the whole ID part is omitted, the last PORT and DEVICE
1209 values are used. If ID hasn't been specified yet, the
1210 configuration applies to all ports, links and devices.
1211
1212 If only DEVICE is omitted, the parameter applies to
1213 the port and all links and devices behind it. DEVICE
1214 number of 0 either selects the first device or the
1215 first fan-out link behind PMP device. It does not
1216 select the host link. DEVICE number of 15 selects the
1217 host link and device attached to it.
1218
1219 The VAL specifies the configuration to force. As long
1220 as there's no ambiguity shortcut notation is allowed.
1221 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1222 The following configurations can be forced.
1223
1224 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1225 Any ID with matching PORT is used.
1226
1227 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1228
1229 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1230 udma[/][16,25,33,44,66,100,133] notation is also
1231 allowed.
1232
1233 * [no]ncq: Turn on or off NCQ.
1234
05944bdf
TH
1235 * nohrst, nosrst, norst: suppress hard, soft
1236 and both resets.
1237
33267325
TH
1238 If there are multiple matching configurations changing
1239 the same attribute, the last one is used.
1240
7c4be253
RD
1241 lmb=debug [KNL] Enable lmb debug messages.
1242
1da177e4 1243 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1244 See Documentation/blockdev/ramdisk.txt.
1da177e4 1245
a6b25b67
RD
1246 lockd.nlm_grace_period=P [NFS] Assign grace period.
1247 Format: <integer>
1da177e4 1248
a6b25b67
RD
1249 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1250 Format: <integer>
1251
1252 lockd.nlm_timeout=T [NFS] Assign timeout value.
1253 Format: <integer>
1254
1255 lockd.nlm_udpport=M [NFS] Assign UDP port.
1256 Format: <integer>
1da177e4
LT
1257
1258 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1259 Format: <irq>
1260
1261 loglevel= All Kernel Messages with a loglevel smaller than the
1262 console loglevel will be printed to the console. It can
1263 also be changed with klogd or other programs. The
1264 loglevels are defined as follows:
1265
1266 0 (KERN_EMERG) system is unusable
1267 1 (KERN_ALERT) action must be taken immediately
1268 2 (KERN_CRIT) critical conditions
1269 3 (KERN_ERR) error conditions
1270 4 (KERN_WARNING) warning conditions
1271 5 (KERN_NOTICE) normal but significant condition
1272 6 (KERN_INFO) informational
1273 7 (KERN_DEBUG) debug-level messages
1274
1275 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1276 Format: { n | nk | nM }
1277 n must be a power of two. The default size
1278 is set in the kernel config file.
1da177e4 1279
accaa24c
RD
1280 logo.nologo [FB] Disables display of the built-in Linux logo.
1281 This may be used to provide more screen space for
1282 kernel log messages and is useful when debugging
1283 kernel boot problems.
1284
1da177e4
LT
1285 lp=0 [LP] Specify parallel ports to use, e.g,
1286 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1287 lp=reset first parallel port). 'lp=0' disables the
1288 lp=auto printer driver. 'lp=reset' (which can be
1289 specified in addition to the ports) causes
1290 attached printers to be reset. Using
1291 lp=port1,port2,... specifies the parallel ports
1292 to associate lp devices with, starting with
1293 lp0. A port specification may be 'none' to skip
1294 that lp device, or a parport name such as
1295 'parport0'. Specifying 'lp=auto' instead of a
1296 port specification list means that device IDs
1297 from each port should be examined, to see if
1298 an IEEE 1284-compliant printer is attached; if
1299 so, the driver will manage that printer.
1300 See also header of drivers/char/lp.c.
1301
1302 lpj=n [KNL]
1303 Sets loops_per_jiffy to given constant, thus avoiding
1304 time-consuming boot-time autodetection (up to 250 ms per
1305 CPU). 0 enables autodetection (default). To determine
1306 the correct value for your kernel, boot with normal
1307 autodetection and see what value is printed. Note that
1308 on SMP systems the preset will be applied to all CPUs,
1309 which is likely to cause problems if your CPUs need
1310 significantly divergent settings. An incorrect value
1311 will cause delays in the kernel to be wrong, leading to
1312 unpredictable I/O errors and other breakage. Although
1313 unlikely, in the extreme case this might damage your
1314 hardware.
1315
1316 ltpc= [NET]
1317 Format: <io>,<irq>,<dma>
1318
a9913044
RD
1319 mac5380= [HW,SCSI] Format:
1320 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1321
a9913044
RD
1322 machvec= [IA64] Force the use of a particular machine-vector
1323 (machvec) in a generic kernel.
1324 Example: machvec=hpzx1_swiotlb
1da177e4 1325
3209e70e
WZ
1326 machtype= [Loongson] Share the same kernel image file between different
1327 yeeloong laptop.
1328 Example: machtype=lemote-yeeloong-2f-7inch
1329
0cb55ad2
RD
1330 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1331 than or equal to this physical address is ignored.
1da177e4
LT
1332
1333 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1334 should make use of. maxcpus=n : n >= 0 limits the
1335 kernel to using 'n' processors. n=0 is a special case,
1336 it is equivalent to "nosmp", which also disables
1337 the IO APIC.
1da177e4 1338
0cb55ad2
RD
1339 max_loop= [LOOP] Maximum number of loopback devices that can
1340 be mounted
1341 Format: <1-256>
2b2c3750 1342
a9913044 1343 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1344 Should be between 1 and 2^32-1.
1345
1346 max_report_luns=
a9913044 1347 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1348 Should be between 1 and 16384.
1349
1da177e4
LT
1350 mcatest= [IA-64]
1351
cd4f0ef7 1352 mce [X86-32] Machine Check Exception
1da177e4 1353
71cced6e 1354 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1355
1da177e4
LT
1356 md= [HW] RAID subsystems devices and level
1357 See Documentation/md.txt.
a9913044 1358
1da177e4
LT
1359 mdacon= [MDA]
1360 Format: <first>,<last>
1361 Specifies range of consoles to be captured by the MDA.
a9913044 1362
1da177e4
LT
1363 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1364 Amount of memory to be used when the kernel is not able
1365 to see the whole system memory or for test.
cd4f0ef7 1366 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1367 address space collisions. Without memmap= PCI devices
1368 could be placed at addresses belonging to unused RAM.
1369
cd4f0ef7 1370 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1371 memory.
1372
6902aa84
PM
1373 memchunk=nn[KMG]
1374 [KNL,SH] Allow user to override the default size for
1375 per-device physically contiguous DMA buffers.
1376
6cececfc 1377 memmap=exactmap [KNL,X86] Enable setting of an exact
1da177e4
LT
1378 E820 memory map, as specified by the user.
1379 Such memmap=exactmap lines can be constructed based on
1380 BIOS output or other requirements. See the memmap=nn@ss
1381 option description.
1382
1383 memmap=nn[KMG]@ss[KMG]
1384 [KNL] Force usage of a specific region of memory
1385 Region of memory to be used, from ss to ss+nn.
1386
1387 memmap=nn[KMG]#ss[KMG]
1388 [KNL,ACPI] Mark specific memory as ACPI data.
1389 Region of memory to be used, from ss to ss+nn.
1390
1391 memmap=nn[KMG]$ss[KMG]
1392 [KNL,ACPI] Mark specific memory as reserved.
1393 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1394 Example: Exclude memory from 0x18690000-0x1869ffff
1395 memmap=64K$0x18690000
1396 or
1397 memmap=0x10000$0x18690000
1da177e4 1398
9f077871
JF
1399 memory_corruption_check=0/1 [X86]
1400 Some BIOSes seem to corrupt the first 64k of
1401 memory when doing things like suspend/resume.
1402 Setting this option will scan the memory
1403 looking for corruption. Enabling this will
1404 both detect corruption and prevent the kernel
1405 from using the memory being corrupted.
1406 However, its intended as a diagnostic tool; if
1407 repeatable BIOS-originated corruption always
1408 affects the same memory, you can use memmap=
1409 to prevent the kernel from using that memory.
1410
1411 memory_corruption_check_size=size [X86]
1412 By default it checks for corruption in the low
1413 64k, making this memory unavailable for normal
1414 use. Use this parameter to scan for
1415 corruption in more or less memory.
1416
1417 memory_corruption_check_period=seconds [X86]
1418 By default it checks for corruption every 60
1419 seconds. Use this parameter to check at some
1420 other rate. 0 disables periodic checking.
1421
caadbdce 1422 memtest= [KNL,X86] Enable memtest
c64df707 1423 Format: <integer>
c64df707 1424 default : 0 <disable>
9e5f6cf5
AH
1425 Specifies the number of memtest passes to be
1426 performed. Each pass selects another test
1427 pattern from a given set of patterns. Memtest
1428 fills the memory with this pattern, validates
1429 memory contents and reserves bad memory
1430 regions that are detected.
c64df707 1431
1da177e4
LT
1432 meye.*= [HW] Set MotionEye Camera parameters
1433 See Documentation/video4linux/meye.txt.
1434
8f36881b
AS
1435 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1436 Multi-Function General Purpose Timers on AMD Geode
1437 platforms.
1438
e6c4dc6c
WT
1439 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1440 the BIOS has incorrectly applied a workaround. TinyBIOS
1441 version 0.98 is known to be affected, 0.99 fixes the
1442 problem by letting the user disable the workaround.
1443
1da177e4
LT
1444 mga= [HW,DRM]
1445
1c207f95
RD
1446 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1447 physical address is ignored.
1448
39f45d7b
MP
1449 mini2440= [ARM,HW,KNL]
1450 Format:[0..2][b][c][t]
1451 Default: "0tb"
1452 MINI2440 configuration specification:
1453 0 - The attached screen is the 3.5" TFT
1454 1 - The attached screen is the 7" TFT
1455 2 - The VGA Shield is attached (1024x768)
1456 Leaving out the screen size parameter will not load
1457 the TFT driver, and the framebuffer will be left
1458 unconfigured.
1459 b - Enable backlight. The TFT backlight pin will be
1460 linked to the kernel VESA blanking code and a GPIO
1461 LED. This parameter is not necessary when using the
1462 VGA shield.
1463 c - Enable the s3c camera interface.
1464 t - Reserved for enabling touchscreen support. The
1465 touchscreen support is not enabled in the mainstream
1466 kernel as of 2.6.30, a preliminary port can be found
1467 in the "bleeding edge" mini2440 support kernel at
1468 http://repo.or.cz/w/linux-2.6/mini2440.git
1469
6b74ab97
MG
1470 mminit_loglevel=
1471 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1472 parameter allows control of the logging verbosity for
1473 the additional memory initialisation checks. A value
1474 of 0 disables mminit logging and a level of 4 will
1475 log everything. Information is printed at KERN_DEBUG
1476 so loglevel=8 may also need to be specified.
1477
1da177e4
LT
1478 mousedev.tap_time=
1479 [MOUSE] Maximum time between finger touching and
1480 leaving touchpad surface for touch to be considered
1481 a tap and be reported as a left button click (for
1482 touchpads working in absolute mode only).
1483 Format: <msecs>
1484 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1485 reporting absolute coordinates, such as tablets
1486 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1487 reporting absolute coordinates, such as tablets
1488
6cececfc 1489 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
0cb55ad2
RD
1490 is similar to kernelcore except it specifies the
1491 amount of memory used for migratable allocations.
1492 If both kernelcore and movablecore is specified,
1493 then kernelcore will be at *least* the specified
1494 value but may be more. If movablecore on its own
1495 is specified, the administrator must be careful
1496 that the amount of memory usable for all allocations
1497 is not too small.
1498
1da177e4
LT
1499 mpu401= [HW,OSS]
1500 Format: <io>,<irq>
1501
1502 MTD_Partition= [MTD]
1503 Format: <name>,<region-number>,<size>,<offset>
1504
a9913044
RD
1505 MTD_Region= [MTD] Format:
1506 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1507
1508 mtdparts= [MTD]
c8facbb6 1509 See drivers/mtd/cmdlinepart.c.
1da177e4 1510
5988af23
RH
1511 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1512
1513 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1514
1515 boundary - index of last SLC block on Flex-OneNAND.
1516 The remaining blocks are configured as MLC blocks.
1517 lock - Configure if Flex-OneNAND boundary should be locked.
1518 Once locked, the boundary cannot be changed.
1519 1 indicates lock status, 0 indicates unlock status.
1520
9db829f4
BD
1521 mtdset= [ARM]
1522 ARM/S3C2412 JIVE boot control
1523
1524 See arch/arm/mach-s3c2412/mach-jive.c
1525
1da177e4 1526 mtouchusb.raw_coordinates=
a9913044
RD
1527 [HW] Make the MicroTouch USB driver use raw coordinates
1528 ('y', default) or cooked coordinates ('n')
1da177e4 1529
0cb55ad2 1530 mtrr_chunk_size=nn[KMG] [X86]
19f59460 1531 used for mtrr cleanup. It is largest continuous chunk
0cb55ad2
RD
1532 that could hold holes aka. UC entries.
1533
1534 mtrr_gran_size=nn[KMG] [X86]
1535 Used for mtrr cleanup. It is granularity of mtrr block.
1536 Default is 1.
1537 Large value could prevent small alignment from
1538 using up MTRRs.
1539
1540 mtrr_spare_reg_nr=n [X86]
1541 Format: <integer>
1542 Range: 0,7 : spare reg number
1543 Default : 1
1544 Used for mtrr cleanup. It is spare mtrr entries number.
1545 Set to 2 or more if your graphical card needs more.
1546
1da177e4
LT
1547 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1548
1549 NCR_D700= [HW,SCSI]
1550 See header of drivers/scsi/NCR_D700.c.
1551
1552 ncr5380= [HW,SCSI]
1553
1554 ncr53c400= [HW,SCSI]
1555
1556 ncr53c400a= [HW,SCSI]
1557
1558 ncr53c406a= [HW,SCSI]
1559
1560 ncr53c8xx= [HW,SCSI]
1561
1562 netdev= [NET] Network devices parameters
1563 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1564 Note that mem_start is often overloaded to mean
1565 something different and driver-specific.
a9913044
RD
1566 This usage is only documented in each driver source
1567 file if at all.
1568
58401572
KPO
1569 nf_conntrack.acct=
1570 [NETFILTER] Enable connection tracking flow accounting
1571 0 to disable accounting
1572 1 to enable accounting
1573 Default value depends on CONFIG_NF_CT_ACCT that is
1574 going to be removed in 2.6.29.
1575
1da177e4 1576 nfsaddrs= [NFS]
dc7a0816 1577 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1578
1579 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
dc7a0816 1580 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4 1581
a72b4422
TM
1582 nfs.callback_tcpport=
1583 [NFS] set the TCP port on which the NFSv4 callback
1584 channel should listen.
1585
e571cbf1
TM
1586 nfs.cache_getent=
1587 [NFS] sets the pathname to the program which is used
1588 to update the NFS client cache entries.
1589
1590 nfs.cache_getent_timeout=
1591 [NFS] sets the timeout after which an attempt to
1592 update a cache entry is deemed to have failed.
1593
58df095b
TM
1594 nfs.idmap_cache_timeout=
1595 [NFS] set the maximum lifetime for idmapper cache
1596 entries.
1597
f43bf0be
TM
1598 nfs.enable_ino64=
1599 [NFS] enable 64-bit inode numbers.
1600 If zero, the NFS client will fake up a 32-bit inode
1601 number for the readdir() and stat() syscalls instead
1602 of returning the full 64-bit number.
1603 The default is to return 64-bit inode numbers.
1604
1e1030dc 1605 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
e7ba176b
HS
1606 when a NMI is triggered.
1607 Format: [state][,regs][,debounce][,die]
1608
6cececfc 1609 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
5b9a0e14
CG
1610 Format: [panic,][num]
1611 Valid num: 0,1,2
1612 0 - turn nmi_watchdog off
1613 1 - use the IO-APIC timer for the NMI watchdog
1614 2 - use the local APIC for the NMI watchdog using
0cb55ad2
RD
1615 a performance counter. Note: This will use one
1616 performance counter and the local APIC's performance
1617 vector.
1618 When panic is specified, panic when an NMI watchdog
1619 timeout occurs.
1620 This is useful when you use a panic=... timeout and
1621 need the box quickly up again.
5b9a0e14
CG
1622 Instead of 1 and 2 it is possible to use the following
1623 symbolic names: lapic and ioapic
1624 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1da177e4 1625
bff38771
AV
1626 netpoll.carrier_timeout=
1627 [NET] Specifies amount of time (in seconds) that
1628 netpoll should wait for a carrier. By default netpoll
1629 waits 4 seconds.
1630
cd4f0ef7 1631 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1632 emulation library even if a 387 maths coprocessor
1633 is present.
1634
0cb55ad2
RD
1635 no_console_suspend
1636 [HW] Never suspend the console
1637 Disable suspending of consoles during suspend and
1638 hibernate operations. Once disabled, debugging
1639 messages can reach various consoles while the rest
1640 of the system is being put to sleep (ie, while
1641 debugging driver suspend/resume hooks). This may
1642 not work reliably with all consoles, but is known
1643 to work with serial and VGA consoles.
1644
c1aee215
CL
1645 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1646 caches in the slab allocator. Saves per-node memory,
1647 but will impact performance.
3395ee05 1648
a9913044
RD
1649 noalign [KNL,ARM]
1650
1da177e4
LT
1651 noapic [SMP,APIC] Tells the kernel to not make use of any
1652 IOAPICs that may be present in the system.
1653
1da177e4
LT
1654 nobats [PPC] Do not use BATs for mapping kernel lowmem
1655 on "Classic" PPC cores.
1656
1657 nocache [ARM]
a9913044 1658
0cb55ad2
RD
1659 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1660
163ecdff
SN
1661 nodelayacct [KNL] Disable per-task delay accounting
1662
1da177e4
LT
1663 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1664
6902aa84
PM
1665 nodsp [SH] Disable hardware DSP at boot time.
1666
6cececfc 1667 noefi [X86] Disable EFI runtime services support.
8b2cb7a8 1668
1da177e4
LT
1669 noexec [IA-64]
1670
6cececfc 1671 noexec [X86]
f5a1b191 1672 On X86-32 available only on PAE configured kernels.
1da177e4 1673 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1674 noexec=off: disable non-executable mappings
1675
1676 noexec32 [X86-64]
1677 This affects only 32-bit executables.
1678 noexec32=on: enable non-executable mappings (default)
1679 read doesn't imply executable mappings
1680 noexec32=off: disable non-executable mappings
1681 read implies executable mappings
1da177e4 1682
6902aa84
PM
1683 nofpu [SH] Disable hardware FPU at boot time.
1684
cd4f0ef7 1685 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1686 register save and restore. The kernel will only save
1687 legacy floating-point registers on task switch.
1da177e4 1688
0c752a93
SS
1689 noxsave [BUGS=X86] Disables x86 extended register state save
1690 and restore using xsave. The kernel will fallback to
1691 enabling legacy floating-point and sse state.
1692
01a24d2b
PZ
1693 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1694 wfi(ARM) instruction doesn't work correctly and not to
1695 use it. This is also useful when using JTAG debugger.
a9913044 1696
cd4f0ef7 1697 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1698 instruction doesn't work correctly and not to
1699 use it.
1700
1f29fae2
SH
1701 no_file_caps Tells the kernel not to honor file capabilities. The
1702 only way then for a file to be executed with privilege
1703 is to be setuid root or executed by root.
1704
1da177e4
LT
1705 nohalt [IA-64] Tells the kernel not to use the power saving
1706 function PAL_HALT_LIGHT when idle. This increases
1707 power-consumption. On the positive side, it reduces
1708 interrupt wake-up latency, which may improve performance
1709 in certain environments such as networked servers or
1710 real-time systems.
1711
79bf2bb3
TG
1712 nohz= [KNL] Boottime enable/disable dynamic ticks
1713 Valid arguments: on, off
1714 Default: on
1715
eeee7853
PM
1716 noiotrap [SH] Disables trapped I/O port accesses.
1717
cd4f0ef7 1718 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1719 disable unhandled interrupt sources.
1720
6cececfc 1721 no_timer_check [X86,APIC] Disables the code which tests for
8542b200
ZA
1722 broken timer IRQ sources.
1723
1da177e4
LT
1724 noisapnp [ISAPNP] Disables ISA PnP code.
1725
1726 noinitrd [RAM] Tells the kernel not to load any configured
1727 initial RAM disk.
1728
03ea8155
WH
1729 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1730 remapping.
1731
1da177e4
LT
1732 nointroute [IA-64]
1733
0aa366f3
TL
1734 nojitter [IA64] Disables jitter checking for ITC timers.
1735
cd4f0ef7 1736 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1737
cd4f0ef7 1738 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1739
1da177e4
LT
1740 noltlbs [PPC] Do not use large page/tlb entries for kernel
1741 lowmem mapping on PPC40x.
1742
312f1f01
H
1743 nomca [IA-64] Disable machine check abort handling
1744
cd4f0ef7 1745 nomce [X86-32] Machine Check Exception
abe37e5a 1746
83d7384f
AS
1747 nomfgpt [X86-32] Disable Multi-Function General Purpose
1748 Timer usage (for AMD Geode machines).
1749
016ddd9b
JK
1750 nopat [X86] Disable PAT (page attribute table extension of
1751 pagetables) support.
1752
0cb55ad2
RD
1753 norandmaps Don't use address space randomization. Equivalent to
1754 echo 0 > /proc/sys/kernel/randomize_va_space
1755
cd4f0ef7 1756 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1757
cd4f0ef7 1758 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1759 with UP alternatives
1760
1da177e4
LT
1761 noresidual [PPC] Don't use residual data on PReP machines.
1762
a9913044
RD
1763 noresume [SWSUSP] Disables resume and restores original swap
1764 space.
1765
1da177e4
LT
1766 no-scroll [VGA] Disables scrollback.
1767 This is required for the Braillex ib80-piezo Braille
1768 reader made by F.H. Papenmeier (Germany).
1769
1770 nosbagart [IA-64]
1771
cd4f0ef7 1772 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1773
61ec7567
LB
1774 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1775 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1776
97842216
DJ
1777 nosoftlockup [KNL] Disable the soft-lockup detector.
1778
c077719b 1779 noswapaccount [KNL] Disable accounting of swap in memory resource
21acb9ca 1780 controller. (See Documentation/cgroups/memory.txt)
c077719b 1781
1da177e4
LT
1782 nosync [HW,M68K] Disables sync negotiation for all devices.
1783
cd4f0ef7 1784 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1785
1786 nousb [USB] Disable the USB subsystem
1787
1788 nowb [ARM]
a9913044 1789
2b2fd87a
WH
1790 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1791
a6c75b86
FY
1792 nptcg= [IA64] Override max number of concurrent global TLB
1793 purges which is reported from either PAL_VM_SUMMARY or
1794 SAL PALO.
1795
2b633e3f
YL
1796 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1797 could support. nr_cpus=n : n >= 1 limits the kernel to
1798 supporting 'n' processors. Later in runtime you can not
1799 use hotplug cpu feature to put more cpu back to online.
1800 just like you compile the kernel NR_CPUS=n
1801
0cb55ad2
RD
1802 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1803
f0c0b2b8
KH
1804 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1805 one of ['zone', 'node', 'default'] can be specified
1806 This can be set from sysctl after boot.
1807 See Documentation/sysctl/vm.txt for details.
1808
7c4be253
RD
1809 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1810 See Documentation/debugging-via-ohci1394.txt for more
1811 info.
1812
3ef0e1f8
AS
1813 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1814 Rather than timing out after 20 ms if an EC
1815 command is not properly ACKed, override the length
1816 of the timeout. We have interrupts disabled while
1817 waiting for the ACK, so if this is set too high
1818 interrupts *may* be lost!
1819
15ac7afe
TL
1820 omap_mux= [OMAP] Override bootloader pin multiplexing.
1821 Format: <mux_mode0.mode_name=value>...
1822 For example, to override I2C bus2:
1823 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1824
1da177e4
LT
1825 opl3= [HW,OSS]
1826 Format: <io>
1827
1da177e4
LT
1828 oprofile.timer= [HW]
1829 Use timer interrupt instead of performance counters
1830
7e4e0bd5
RR
1831 oprofile.cpu_type= Force an oprofile cpu type
1832 This might be useful if you have an older oprofile
1833 userland or if you want common events.
8d7ff4f2
RR
1834 Format: { arch_perfmon }
1835 arch_perfmon: [X86] Force use of architectural
7e4e0bd5
RR
1836 perfmon on Intel CPUs instead of the
1837 CPU specific event set.
1dcdb5a9 1838
1da177e4
LT
1839 osst= [HW,SCSI] SCSI Tape Driver
1840 Format: <buffer_size>,<write_threshold>
1841 See also Documentation/scsi/st.txt.
1842
1843 panic= [KNL] Kernel behaviour on panic
1844 Format: <timeout>
1845
1846 parkbd.port= [HW] Parallel port number the keyboard adapter is
1847 connected to, default is 0.
1848 Format: <parport#>
1849 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1850 0 for XT, 1 for AT (default is AT).
a9913044
RD
1851 Format: <mode>
1852
1853 parport= [HW,PPT] Specify parallel ports. 0 disables.
1854 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1855 Use 'auto' to force the driver to use any
1856 IRQ/DMA settings detected (the default is to
1857 ignore detected IRQ/DMA settings because of
1858 possible conflicts). You can specify the base
1859 address, IRQ, and DMA settings; IRQ and DMA
1860 should be numbers, or 'auto' (for using detected
1861 settings on that particular port), or 'nofifo'
1862 (to avoid using a FIFO even if it is detected).
1863 Parallel ports are assigned in the order they
1864 are specified on the command line, starting
1865 with parport0.
1866
1867 parport_init_mode= [HW,PPT]
1868 Configure VIA parallel port to operate in
1869 a specific mode. This is necessary on Pegasos
1870 computer where firmware has no options for setting
1871 up parallel port mode and sets it to spp.
1872 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1873 Format: [spp|ps2|epp|ecp|ecpepp]
1874
a9913044
RD
1875 pas2= [HW,OSS] Format:
1876 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1877
1da177e4
LT
1878 pas16= [HW,SCSI]
1879 See header of drivers/scsi/pas16.c.
1880
dd287796
AM
1881 pause_on_oops=
1882 Halt all CPUs after the first oops has been printed for
1883 the specified number of seconds. This is to be used if
1884 your oopses keep scrolling off the screen.
1885
1da177e4
LT
1886 pcbit= [HW,ISDN]
1887
1888 pcd. [PARIDE]
1889 See header of drivers/block/paride/pcd.c.
31c00fc1 1890 See also Documentation/blockdev/paride.txt.
1da177e4 1891
a9913044 1892 pci=option[,option...] [PCI] various PCI subsystem options:
1cc0ca26
BH
1893 earlydump [X86] dump PCI config space before the kernel
1894 changes anything
c0115606 1895 off [X86] don't probe for the PCI bus
cd4f0ef7 1896 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1897 the hardware directly. Use this if your machine
1898 has a non-standard PCI host bridge.
cd4f0ef7 1899 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1900 hardware access methods are allowed. Use this
1901 if you experience crashes upon bootup and you
1902 suspect they are caused by the BIOS.
c0115606 1903 conf1 [X86] Force use of PCI Configuration
a9913044 1904 Mechanism 1.
c0115606 1905 conf2 [X86] Force use of PCI Configuration
a9913044 1906 Mechanism 2.
7f785763
RD
1907 noaer [PCIE] If the PCIEAER kernel config parameter is
1908 enabled, this kernel boot option can be used to
1909 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1910 nodomains [PCI] Disable support for multiple PCI
1911 root domains (aka PCI segments, in ACPI-speak).
6cececfc 1912 nommconf [X86] Disable use of MMCONFIG for PCI
61be6d66 1913 Configuration
12983077
AH
1914 check_enable_amd_mmconf [X86] check for and enable
1915 properly configured MMIO access to PCI
1916 config space on AMD family 10h CPU
309e57df
MW
1917 nomsi [MSI] If the PCI_MSI kernel config parameter is
1918 enabled, this kernel boot option can be used to
1919 disable the use of MSI interrupts system-wide.
a9322f64
SA
1920 noioapicquirk [APIC] Disable all boot interrupt quirks.
1921 Safety option to keep boot IRQs enabled. This
1922 should never be necessary.
9197979b
SA
1923 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1924 primary IO-APIC for bridges that cannot disable
1925 boot IRQs. This fixes a source of spurious IRQs
1926 when the system masks IRQs.
41b9eb26
SA
1927 noioapicreroute [APIC] Disable workaround that uses the
1928 boot IRQ equivalent of an IRQ that connects to
1929 a chipset where boot IRQs cannot be disabled.
1930 The opposite of ioapicreroute.
cd4f0ef7 1931 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1932 routing table. These calls are known to be buggy
1933 on several machines and they hang the machine
1934 when used, but on other computers it's the only
1935 way to get the interrupt routing table. Try
1936 this option if the kernel is unable to allocate
1937 IRQs or discover secondary PCI buses on your
1938 motherboard.
c0115606 1939 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1940 Use with caution as certain devices share
1941 address decoders between ROMs and other
1942 resources.
c0115606 1943 norom [X86] Do not assign address space to
bb71ad88
GH
1944 expansion ROMs that do not already have
1945 BIOS assigned address ranges.
c0115606 1946 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1947 assigned automatically to PCI devices. You can
1948 make the kernel exclude IRQs of your ISA cards
1949 this way.
c0115606 1950 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1951 of the PIRQ table (normally generated
1952 by the BIOS) if it is outside the
1953 F0000h-100000h range.
c0115606 1954 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1955 useful if the kernel is unable to find your
1956 secondary buses and you want to tell it
1957 explicitly which ones they are.
c0115606 1958 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1959 numbers ourselves, overriding
1960 whatever the firmware may have done.
c0115606 1961 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1962 in the BIOS $PIR table. This is needed on
1963 some systems with broken BIOSes, notably
1964 some HP Pavilion N5400 and Omnibook XE3
1965 notebooks. This will have no effect if ACPI
1966 IRQ routing is enabled.
c0115606 1967 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1968 or for PCI scanning.
7bc5e3f2
BH
1969 use_crs [X86] Use PCI host bridge window information
1970 from ACPI. On BIOSes from 2008 or later, this
1971 is enabled by default. If you need to use this,
1972 please report a bug.
1973 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1974 If you need to use this, please report a bug.
a9913044
RD
1975 routeirq Do IRQ routing for all PCI devices.
1976 This is normally done in pci_enable_device(),
1977 so this option is a temporary workaround
1978 for broken drivers that don't call it.
13a6ddb0
YL
1979 skip_isa_align [X86] do not align io start addr, so can
1980 handle more pci cards
a9913044
RD
1981 firmware [ARM] Do not re-enumerate the bus but instead
1982 just use the configuration from the
1983 bootloader. This is currently used on
1984 IXP2000 systems where the bus has to be
1985 configured a certain way for adjunct CPUs.
0637a70a
AK
1986 noearly [X86] Don't do any early type 1 scanning.
1987 This might help on some broken boards which
1988 machine check when some devices' config space
1989 is read. But various workarounds are disabled
1990 and some IOMMU drivers will not work.
6b4b78fe
MD
1991 bfsort Sort PCI devices into breadth-first order.
1992 This sorting is done to get a device
1993 order compatible with older (<= 2.4) kernels.
1994 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1995 cbiosize=nn[KMG] The fixed amount of bus space which is
1996 reserved for the CardBus bridge's IO window.
1997 The default value is 256 bytes.
1998 cbmemsize=nn[KMG] The fixed amount of bus space which is
1999 reserved for the CardBus bridge's memory
2000 window. The default value is 64 megabytes.
32a9a682
YS
2001 resource_alignment=
2002 Format:
2003 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2004 Specifies alignment and device to reassign
2005 aligned memory resources.
2006 If <order of align> is not specified,
2007 PAGE_SIZE is used as alignment.
2008 PCI-PCI bridge can be specified, if resource
2009 windows need to be expanded.
43c16408
AP
2010 ecrc= Enable/disable PCIe ECRC (transaction layer
2011 end-to-end CRC checking).
2012 bios: Use BIOS/firmware settings. This is the
2013 the default.
2014 off: Turn ECRC off
2015 on: Turn ECRC on.
6b4b78fe 2016
e5665a45
CE
2017 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2018 Management.
2019 off Disable ASPM.
2020 force Enable ASPM even on devices that claim not to support it.
2021 WARNING: Forcing ASPM on may cause system lockups.
2022
c7f48656
RW
2023 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2024 off Do not use native PCIe PME signaling.
2025 force Use native PCIe PME signaling even if the BIOS refuses
2026 to allow the kernel to control the relevant PCIe config
2027 registers.
c39fae14
RW
2028 nomsi Do not use MSI for native PCIe PME signaling (this makes
2029 all PCIe root ports use INTx for everything).
c7f48656 2030
1da177e4
LT
2031 pcmv= [HW,PCMCIA] BadgePAD 4
2032
2033 pd. [PARIDE]
31c00fc1 2034 See Documentation/blockdev/paride.txt.
1da177e4
LT
2035
2036 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2037 boot time.
2038 Format: { 0 | 1 }
2039 See arch/parisc/kernel/pdc_chassis.c
2040
f58dc01b 2041 percpu_alloc= Select which percpu first chunk allocator to use.
e933a73f
TH
2042 Currently supported values are "embed" and "page".
2043 Archs may support subset or none of the selections.
2044 See comments in mm/percpu.c for details on each
2045 allocator. This parameter is primarily for debugging
2046 and performance comparison.
fa8a7094 2047
1da177e4 2048 pf. [PARIDE]
31c00fc1 2049 See Documentation/blockdev/paride.txt.
1da177e4
LT
2050
2051 pg. [PARIDE]
31c00fc1 2052 See Documentation/blockdev/paride.txt.
1da177e4
LT
2053
2054 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 2055 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
2056
2057 plip= [PPT,NET] Parallel port network link
2058 Format: { parport<nr> | timid | 0 }
2059 See also Documentation/parport.txt.
2060
de32a243
TG
2061 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2062 Override pmtimer IOPort with a hex value.
2063 e.g. pmtmr=0x508
2064
97ef062b
BH
2065 pnp.debug [PNP]
2066 Enable PNP debug messages. This depends on the
2067 CONFIG_PNP_DEBUG_MESSAGES option.
2068
1da177e4
LT
2069 pnpacpi= [ACPI]
2070 { off }
2071
2072 pnpbios= [ISAPNP]
2073 { on | off | curr | res | no-curr | no-res }
2074
2075 pnp_reserve_irq=
2076 [ISAPNP] Exclude IRQs for the autoconfiguration
2077
2078 pnp_reserve_dma=
2079 [ISAPNP] Exclude DMAs for the autoconfiguration
2080
2081 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 2082 Ranges are in pairs (I/O port base and size).
1da177e4
LT
2083
2084 pnp_reserve_mem=
a9913044
RD
2085 [ISAPNP] Exclude memory regions for the
2086 autoconfiguration.
1da177e4
LT
2087 Ranges are in pairs (memory base and size).
2088
4af94f39
RD
2089 ports= [IP_VS_FTP] IPVS ftp helper module
2090 Default is 21.
2091 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2092 may be specified.
2093 Format: <port>,<port>....
2094
45807a1d
IM
2095 print-fatal-signals=
2096 [KNL] debug: print fatal signals
f84d49b2
NO
2097
2098 If enabled, warn about various signal handling
2099 related application anomalies: too many signals,
2100 too many POSIX.1 timers, fatal signals causing a
2101 coredump - etc.
2102
2103 If you hit the warning due to signal overflow,
2104 you might want to try "ulimit -i unlimited".
2105
45807a1d
IM
2106 default: off.
2107
e84845c4
RD
2108 printk.time= Show timing data prefixed to each printk message line
2109 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2110
0cb55ad2
RD
2111 processor.max_cstate= [HW,ACPI]
2112 Limit processor to maximum C-state
2113 max_cstate=9 overrides any DMI blacklist limit.
2114
2115 processor.nocst [HW,ACPI]
2116 Ignore the _CST method to determine C-states,
2117 instead using the legacy FADT method
2118
1da177e4 2119 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
2120 Format: [schedule,]<number>
2121 Param: "schedule" - profile schedule points.
2122 Param: <number> - step/bucket size as a power of 2 for
2123 statistical time based profiling.
b3da2a73
MG
2124 Param: "sleep" - profile D-state sleeping (millisecs).
2125 Requires CONFIG_SCHEDSTATS
c0fe2e69 2126 Param: "kvm" - profile VM exits.
1da177e4 2127
1da177e4
LT
2128 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2129 before loading.
31c00fc1 2130 See Documentation/blockdev/ramdisk.txt.
1da177e4 2131
a9913044
RD
2132 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2133 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
2134 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2135 per second.
a9913044
RD
2136 psmouse.resetafter= [HW,MOUSE]
2137 Try to reset the device after so many bad packets
1da177e4
LT
2138 (0 = never).
2139 psmouse.resolution=
2140 [HW,MOUSE] Set desired mouse resolution, in dpi.
2141 psmouse.smartscroll=
a9913044 2142 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
2143 0 = disabled, 1 = enabled (default).
2144
2145 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
2146 Format:
2147 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
2148
2149 pt. [PARIDE]
31c00fc1 2150 See Documentation/blockdev/paride.txt.
1da177e4 2151
dc8c8587
KS
2152 pty.legacy_count=
2153 [KNL] Number of legacy pty's. Overwrites compiled-in
2154 default number.
2155
7d2c502f 2156 quiet [KNL] Disable most log messages
a9913044 2157
1da177e4
LT
2158 r128= [HW,DRM]
2159
2160 raid= [HW,RAID]
2161 See Documentation/md.txt.
2162
a9913044 2163 ramdisk_blocksize= [RAM]
31c00fc1 2164 See Documentation/blockdev/ramdisk.txt.
a9913044 2165
1da177e4 2166 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 2167 See Documentation/blockdev/ramdisk.txt.
1da177e4 2168
24aaef8d
RD
2169 rcupdate.blimit= [KNL,BOOT]
2170 Set maximum number of finished RCU callbacks to process
2171 in one batch.
21a1ea9e 2172
24aaef8d
RD
2173 rcupdate.qhimark= [KNL,BOOT]
2174 Set threshold of queued
21a1ea9e
DS
2175 RCU callbacks over which batch limiting is disabled.
2176
24aaef8d
RD
2177 rcupdate.qlowmark= [KNL,BOOT]
2178 Set threshold of queued RCU callbacks below which
2179 batch limiting is re-enabled.
21a1ea9e 2180
ffdfc409
OJ
2181 rdinit= [KNL]
2182 Format: <full_path>
2183 Run specified binary instead of /init from the ramdisk,
2184 used for early userspace startup. See initrd.
2185
cd4f0ef7 2186 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 2187 Format: <reboot_mode>[,<reboot_mode2>[,...]]
ecb08d81 2188 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 2189
46b6d94e
PJ
2190 relax_domain_level=
2191 [KNL, SMP] Set scheduler's default relax_domain_level.
21acb9ca 2192 See Documentation/cgroups/cpusets.txt.
46b6d94e 2193
1da177e4
LT
2194 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2195
cd4f0ef7 2196 reservetop= [X86-32]
461a9aff
ZA
2197 Format: nn[KMG]
2198 Reserves a hole at the top of the kernel virtual
2199 address space.
2200
7e96287d
VG
2201 reset_devices [KNL] Force drivers to reset the underlying device
2202 during initialization.
2203
a9913044
RD
2204 resume= [SWSUSP]
2205 Specify the partition device for software suspend
1da177e4 2206
ecbd0da1
RW
2207 resume_offset= [SWSUSP]
2208 Specify the offset from the beginning of the partition
2209 given by "resume=" at which the swap header is located,
2210 in <PAGE_SIZE> units (needed only for swap files).
2211 See Documentation/power/swsusp-and-swap-files.txt
2212
0a7b35cb
MN
2213 retain_initrd [RAM] Keep initrd memory after extraction
2214
1da177e4
LT
2215 rhash_entries= [KNL,NET]
2216 Set number of hash buckets for route cache
2217
2218 riscom8= [HW,SERIAL]
2219 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2220
2221 ro [KNL] Mount root device read-only on boot
2222
2223 root= [KNL] Root filesystem
2224
2225 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2226 mount the root filesystem
2227
2228 rootflags= [KNL] Set root filesystem mount option string
2229
2230 rootfstype= [KNL] Set root filesystem type
2231
cc1ed754
PO
2232 rootwait [KNL] Wait (indefinitely) for root device to show up.
2233 Useful for devices that are detected asynchronously
2234 (e.g. USB and MMC devices).
2235
1da177e4
LT
2236 rw [KNL] Mount root device read-write on boot
2237
2238 S [KNL] Run init in single mode
2239
2240 sa1100ir [NET]
2241 See drivers/net/irda/sa1100_ir.c.
2242
1da177e4 2243 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 2244
f6630114
MT
2245 sched_debug [KNL] Enables verbose scheduler debug messages.
2246
1da177e4
LT
2247 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2248 Format: <io>[,<timeout>[,<isapnp>]]
2249
2250 scsi_debug_*= [SCSI]
2251 See drivers/scsi/scsi_debug.c.
2252
2253 scsi_default_dev_flags=
2254 [SCSI] SCSI default device flags
2255 Format: <integer>
2256
2257 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2258 Format: <vendor>:<model>:<flags>
2259 (flags are integer value)
2260
6af6632a
RD
2261 scsi_logging_level= [SCSI] a bit mask of logging levels
2262 See drivers/scsi/scsi_logging.h for bits. Also
2263 settable via sysctl at dev.scsi.logging_level
2264 (/proc/sys/dev/scsi/logging_level).
2265 There is also a nice 'scsi_logging_level' script in the
2266 S390-tools package, available for download at
2267 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 2268
3e082a91
MW
2269 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2270 discovered. async scans them in kernel threads,
2271 allowing boot to proceed. none ignores them, expecting
2272 user space to do the scan.
2273
0cb55ad2
RD
2274 security= [SECURITY] Choose a security module to enable at boot.
2275 If this boot parameter is not specified, only the first
2276 security module asking for security registration will be
2277 loaded. An invalid security module name will be treated
2278 as if no module has been chosen.
2279
2280 selinux= [SELINUX] Disable or enable SELinux at boot time.
1da177e4
LT
2281 Format: { "0" | "1" }
2282 See security/selinux/Kconfig help text.
2283 0 -- disable.
2284 1 -- enable.
2285 Default value is set via kernel config option.
2286 If enabled at boot time, /selinux/disable can be used
2287 later to disable prior to initial policy load.
2288
cd4f0ef7 2289 serialnumber [BUGS=X86-32]
1da177e4 2290
1da177e4
LT
2291 shapers= [NET]
2292 Maximal number of shapers.
a9913044 2293
b05f78f5
YL
2294 show_msr= [x86] show boot-time MSR settings
2295 Format: { <integer> }
2296 Show boot-time (BIOS-initialized) MSR settings.
2297 The parameter means the number of CPUs to show,
2298 for example 1 means boot CPU only.
2299
1da177e4
LT
2300 sim710= [SCSI,HW]
2301 See header of drivers/scsi/sim710.c.
2302
2303 simeth= [IA-64]
2304 simscsi=
a9913044 2305
1da177e4
LT
2306 slram= [HW,MTD]
2307
f0630fff
CL
2308 slub_debug[=options[,slabs]] [MM, SLUB]
2309 Enabling slub_debug allows one to determine the
2310 culprit if slab objects become corrupted. Enabling
2311 slub_debug can create guard zones around objects and
2312 may poison objects when not in use. Also tracks the
2313 last alloc / free. For more information see
2314 Documentation/vm/slub.txt.
c1aee215
CL
2315
2316 slub_max_order= [MM, SLUB]
f0630fff
CL
2317 Determines the maximum allowed order for slabs.
2318 A high setting may cause OOMs due to memory
2319 fragmentation. For more information see
2320 Documentation/vm/slub.txt.
c1aee215
CL
2321
2322 slub_min_objects= [MM, SLUB]
f0630fff
CL
2323 The minimum number of objects per slab. SLUB will
2324 increase the slab order up to slub_max_order to
2325 generate a sufficiently large slab able to contain
2326 the number of objects indicated. The higher the number
2327 of objects the smaller the overhead of tracking slabs
2328 and the less frequently locks need to be acquired.
c1aee215
CL
2329 For more information see Documentation/vm/slub.txt.
2330
2331 slub_min_order= [MM, SLUB]
2332 Determines the mininum page order for slabs. Must be
f0630fff 2333 lower than slub_max_order.
c1aee215
CL
2334 For more information see Documentation/vm/slub.txt.
2335
2336 slub_nomerge [MM, SLUB]
f0630fff 2337 Disable merging of slabs with similar size. May be
c1aee215 2338 necessary if there is some reason to distinguish
f0630fff
CL
2339 allocs to different slabs. Debug options disable
2340 merging on their own.
c1aee215
CL
2341 For more information see Documentation/vm/slub.txt.
2342
1da177e4
LT
2343 smart2= [HW]
2344 Format: <io1>[,<io2>[,...,<io8>]]
2345
cd4f0ef7 2346 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2347 attempt to substitute SMP alternatives once at boot.
2348
d0d4f69b
BH
2349 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2350 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2351 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2352 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2353 smsc-ircc2.ircc_irq= [HW] IRQ line
2354 smsc-ircc2.ircc_dma= [HW] DMA channel
2355 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2356 0: Toshiba Satellite 1800 (GP data pin select)
2357 1: Fast pin select (default)
2358 2: ATC IRMode
2359
1da177e4
LT
2360 snd-ad1816a= [HW,ALSA]
2361
2362 snd-ad1848= [HW,ALSA]
2363
2364 snd-ali5451= [HW,ALSA]
2365
2366 snd-als100= [HW,ALSA]
2367
2368 snd-als4000= [HW,ALSA]
2369
2370 snd-azt2320= [HW,ALSA]
2371
2372 snd-cmi8330= [HW,ALSA]
2373
2374 snd-cmipci= [HW,ALSA]
2375
2376 snd-cs4231= [HW,ALSA]
2377
2378 snd-cs4232= [HW,ALSA]
2379
2380 snd-cs4236= [HW,ALSA]
2381
2382 snd-cs4281= [HW,ALSA]
2383
2384 snd-cs46xx= [HW,ALSA]
2385
2386 snd-dt019x= [HW,ALSA]
2387
2388 snd-dummy= [HW,ALSA]
2389
2390 snd-emu10k1= [HW,ALSA]
2391
2392 snd-ens1370= [HW,ALSA]
2393
2394 snd-ens1371= [HW,ALSA]
2395
2396 snd-es968= [HW,ALSA]
2397
2398 snd-es1688= [HW,ALSA]
2399
2400 snd-es18xx= [HW,ALSA]
2401
2402 snd-es1938= [HW,ALSA]
2403
2404 snd-es1968= [HW,ALSA]
2405
2406 snd-fm801= [HW,ALSA]
2407
2408 snd-gusclassic= [HW,ALSA]
2409
2410 snd-gusextreme= [HW,ALSA]
2411
2412 snd-gusmax= [HW,ALSA]
2413
2414 snd-hdsp= [HW,ALSA]
2415
2416 snd-ice1712= [HW,ALSA]
2417
2418 snd-intel8x0= [HW,ALSA]
2419
2420 snd-interwave= [HW,ALSA]
2421
2422 snd-interwave-stb=
2423 [HW,ALSA]
2424
2425 snd-korg1212= [HW,ALSA]
2426
2427 snd-maestro3= [HW,ALSA]
2428
2429 snd-mpu401= [HW,ALSA]
2430
2431 snd-mtpav= [HW,ALSA]
2432
2433 snd-nm256= [HW,ALSA]
2434
2435 snd-opl3sa2= [HW,ALSA]
2436
2437 snd-opti92x-ad1848=
2438 [HW,ALSA]
2439
2440 snd-opti92x-cs4231=
2441 [HW,ALSA]
2442
2443 snd-opti93x= [HW,ALSA]
2444
2445 snd-pmac= [HW,ALSA]
2446
2447 snd-rme32= [HW,ALSA]
2448
2449 snd-rme96= [HW,ALSA]
2450
2451 snd-rme9652= [HW,ALSA]
2452
2453 snd-sb8= [HW,ALSA]
2454
2455 snd-sb16= [HW,ALSA]
2456
2457 snd-sbawe= [HW,ALSA]
2458
2459 snd-serial= [HW,ALSA]
2460
2461 snd-sgalaxy= [HW,ALSA]
2462
2463 snd-sonicvibes= [HW,ALSA]
2464
2465 snd-sun-amd7930=
2466 [HW,ALSA]
2467
2468 snd-sun-cs4231= [HW,ALSA]
2469
2470 snd-trident= [HW,ALSA]
2471
2472 snd-usb-audio= [HW,ALSA,USB]
2473
2474 snd-via82xx= [HW,ALSA]
2475
2476 snd-virmidi= [HW,ALSA]
2477
2478 snd-wavefront= [HW,ALSA]
2479
2480 snd-ymfpci= [HW,ALSA]
a9913044 2481
9c44bc03
IM
2482 softlockup_panic=
2483 [KNL] Should the soft-lockup detector generate panics.
2484
1da177e4
LT
2485 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2486 See Documentation/sonypi.txt
2487
2488 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2489 See Documentation/serial/specialix.txt.
1da177e4
LT
2490
2491 spia_io_base= [HW,MTD]
2492 spia_fio_base=
2493 spia_pedr=
2494 spia_peddr=
2495
2496 sscape= [HW,OSS]
2497 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2498
1da177e4
LT
2499 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2500 See Documentation/scsi/st.txt.
2501
f38f1d2a
SR
2502 stacktrace [FTRACE]
2503 Enabled the stack tracer on boot up.
2504
1da177e4
LT
2505 sti= [PARISC,HW]
2506 Format: <num>
2507 Set the STI (builtin display/keyboard on the HP-PARISC
2508 machines) console (graphic card) which should be used
2509 as the initial boot-console.
2510 See also comment in drivers/video/console/sticore.c.
2511
2512 sti_font= [HW]
2513 See comment in drivers/video/console/sticore.c.
2514
2515 stifb= [HW]
2516 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2517
cbf11071
TM
2518 sunrpc.min_resvport=
2519 sunrpc.max_resvport=
2520 [NFS,SUNRPC]
2521 SunRPC servers often require that client requests
2522 originate from a privileged port (i.e. a port in the
2523 range 0 < portnr < 1024).
2524 An administrator who wishes to reserve some of these
2525 ports for other uses may adjust the range that the
2526 kernel's sunrpc client considers to be privileged
2527 using these two parameters to set the minimum and
2528 maximum port values.
2529
42a7fc4a
GB
2530 sunrpc.pool_mode=
2531 [NFS]
2532 Control how the NFS server code allocates CPUs to
2533 service thread pools. Depending on how many NICs
2534 you have and where their interrupts are bound, this
2535 option will affect which CPUs will do NFS serving.
2536 Note: this parameter cannot be changed while the
2537 NFS server is running.
2538
2539 auto the server chooses an appropriate mode
2540 automatically using heuristics
2541 global a single global pool contains all CPUs
2542 percpu one pool for each CPU
2543 pernode one pool for each NUMA node (equivalent
2544 to global on non-NUMA machines)
2545
cbf11071
TM
2546 sunrpc.tcp_slot_table_entries=
2547 sunrpc.udp_slot_table_entries=
2548 [NFS,SUNRPC]
2549 Sets the upper limit on the number of simultaneous
2550 RPC calls that can be sent from the client to a
2551 server. Increasing these values may allow you to
2552 improve throughput, but will also increase the
2553 amount of memory reserved for use by the client.
2554
1da177e4 2555 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2556
1da177e4
LT
2557 switches= [HW,M68k]
2558
2559 sym53c416= [HW,SCSI]
2560 See header of drivers/scsi/sym53c416.c.
2561
5d6f647f
IM
2562 sysrq_always_enabled
2563 [KNL]
2564 Ignore sysrq setting - this boot parameter will
2565 neutralize any effect of /proc/sys/kernel/sysrq.
2566 Useful for debugging.
2567
1da177e4
LT
2568 t128= [HW,SCSI]
2569 See header of drivers/scsi/t128.c.
2570
2571 tdfx= [HW,DRM]
2572
77437fd4
DB
2573 test_suspend= [SUSPEND]
2574 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2575 standby suspend) as the system sleep state to briefly
2576 enter during system startup. The system is woken from
2577 this state using a wakeup-capable RTC alarm.
2578
1da177e4
LT
2579 thash_entries= [KNL,NET]
2580 Set number of hash buckets for TCP connection
2581
f8707ec9
LB
2582 thermal.act= [HW,ACPI]
2583 -1: disable all active trip points in all thermal zones
2584 <degrees C>: override all lowest active trip points
2585
c52a7419
LB
2586 thermal.crt= [HW,ACPI]
2587 -1: disable all critical trip points in all thermal zones
22a94d79 2588 <degrees C>: override all critical trip points
c52a7419 2589
f5487145
LB
2590 thermal.nocrt= [HW,ACPI]
2591 Set to disable actions on ACPI thermal zone
2592 critical and hot trip points.
2593
72b33ef8
LB
2594 thermal.off= [HW,ACPI]
2595 1: disable ACPI thermal control
2596
a70cdc52
LB
2597 thermal.psv= [HW,ACPI]
2598 -1: disable all passive trip points
ada9cfdd
RD
2599 <degrees C>: override all passive trip points to this
2600 value
a70cdc52 2601
730ff34d
LB
2602 thermal.tzp= [HW,ACPI]
2603 Specify global default ACPI thermal zone polling rate
2604 <deci-seconds>: poll all this frequency
2605 0: no polling (default)
2606
1da177e4
LT
2607 tmscsim= [HW,SCSI]
2608 See comment before function dc390_setup() in
2609 drivers/scsi/tmscsim.c.
2610
2b1a61f0
HC
2611 topology= [S390]
2612 Format: {off | on}
2613 Specify if the kernel should make use of the cpu
2614 topology informations if the hardware supports these.
2615 The scheduler will make use of these informations and
2616 e.g. base its process migration decisions on it.
2617 Default is off.
2618
1da177e4
LT
2619 tp720= [HW,PS2]
2620
9d612bef
LZ
2621 trace_buf_size=nn[KMG]
2622 [FTRACE] will set tracing buffer size.
631595fb 2623
020e5f85
LZ
2624 trace_event=[event-list]
2625 [FTRACE] Set and start specified trace events in order
2626 to facilitate early boot debugging.
2627 See also Documentation/trace/events.txt
2628
1da177e4 2629 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2630 Format:
2631 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2632
395628ef
AK
2633 tsc= Disable clocksource-must-verify flag for TSC.
2634 Format: <string>
2635 [x86] reliable: mark tsc clocksource as reliable, this
2636 disables clocksource verification at runtime.
2637 Used to enable high-resolution timer mode on older
2638 hardware, and in virtualized environment.
2639
a9913044
RD
2640 turbografx.map[2|3]= [HW,JOY]
2641 TurboGraFX parallel port interface
2642 Format:
2643 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2644 See also Documentation/input/joystick-parport.txt
2645
2646 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2647 See header of drivers/scsi/u14-34f.c.
2648
2649 uart401= [HW,OSS]
2650 Format: <io>,<irq>
2651
2652 uart6850= [HW,OSS]
2653 Format: <io>,<irq>
2654
f86dcc5a
ED
2655 uhash_entries= [KNL,NET]
2656 Set number of hash buckets for UDP/UDP-Lite connections
2657
5f8364b7
AS
2658 uhci-hcd.ignore_oc=
2659 [USB] Ignore overcurrent events (default N).
2660 Some badly-designed motherboards generate lots of
2661 bogus events, for ports that aren't wired to
2662 anything. Set this parameter to avoid log spamming.
2663 Note that genuine overcurrent events won't be
2664 reported either.
2665
e3a61b0a 2666 unknown_nmi_panic
6cececfc 2667 [X86]
e3a61b0a
SA
2668 Set unknown_nmi_panic=1 early on boot.
2669
b5e795f8
AS
2670 usbcore.autosuspend=
2671 [USB] The autosuspend time delay (in seconds) used
2672 for newly-detected USB devices (default 2). This
2673 is the time required before an idle device will be
2674 autosuspended. Devices for which the delay is set
eaafbc3a 2675 to a negative value won't be autosuspended at all.
b5e795f8 2676
fd7c519d
JK
2677 usbcore.usbfs_snoop=
2678 [USB] Set to log all usbfs traffic (default 0 = off).
2679
2680 usbcore.blinkenlights=
2681 [USB] Set to cycle leds on hubs (default 0 = off).
2682
2683 usbcore.old_scheme_first=
2684 [USB] Start with the old device initialization
2685 scheme (default 0 = off).
2686
2687 usbcore.use_both_schemes=
2688 [USB] Try the other device initialization scheme
2689 if the first one fails (default 1 = enabled).
2690
2691 usbcore.initial_descriptor_timeout=
2692 [USB] Specifies timeout for the initial 64-byte
2693 USB_REQ_GET_DESCRIPTOR request in milliseconds
2694 (default 5000 = 5.0 seconds).
2695
1da177e4
LT
2696 usbhid.mousepoll=
2697 [USBHID] The interval which mice are to be polled at.
a9913044 2698
d4f373e5
AS
2699 usb-storage.delay_use=
2700 [UMS] The delay in seconds before a new device is
2701 scanned for Logical Units (default 5).
2702
2703 usb-storage.quirks=
2704 [UMS] A list of quirks entries to supplement or
2705 override the built-in unusual_devs list. List
2706 entries are separated by commas. Each entry has
2707 the form VID:PID:Flags where VID and PID are Vendor
2708 and Product ID values (4-digit hex numbers) and
2709 Flags is a set of characters, each corresponding
2710 to a common usb-storage quirk flag as follows:
c838ea46
AS
2711 a = SANE_SENSE (collect more than 18 bytes
2712 of sense data);
a0bb1081
AS
2713 b = BAD_SENSE (don't collect more than 18
2714 bytes of sense data);
d4f373e5
AS
2715 c = FIX_CAPACITY (decrease the reported
2716 device capacity by one sector);
c838ea46
AS
2717 h = CAPACITY_HEURISTICS (decrease the
2718 reported device capacity by one
2719 sector if the number is odd);
d4f373e5
AS
2720 i = IGNORE_DEVICE (don't bind to this
2721 device);
2722 l = NOT_LOCKABLE (don't try to lock and
2723 unlock ejectable media);
2724 m = MAX_SECTORS_64 (don't transfer more
2725 than 64 sectors = 32 KB at a time);
c838ea46
AS
2726 o = CAPACITY_OK (accept the capacity
2727 reported by the device);
d4f373e5
AS
2728 r = IGNORE_RESIDUE (the device reports
2729 bogus residue values);
2730 s = SINGLE_LUN (the device has only one
2731 Logical Unit);
2732 w = NO_WP_DETECT (don't test whether the
2733 medium is write-protected).
2734 Example: quirks=0419:aaf5:rl,0421:0433:rc
2735
14315592
IC
2736 userpte=
2737 [X86] Flags controlling user PTE allocations.
2738
2739 nohigh = do not allocate PTE pages in
2740 HIGHMEM regardless of setting
2741 of CONFIG_HIGHPTE.
2742
6cececfc 2743 vdso= [X86,SH]
1dbf527c 2744 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2745 vdso=1: enable VDSO (default)
2746 vdso=0: disable VDSO mapping
2747
6cececfc 2748 vdso32= [X86]
af65d648
RM
2749 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2750 vdso32=1: enable 32-bit VDSO (default)
2751 vdso32=0: disable 32-bit VDSO mapping
2752
d080d397
YI
2753 vector= [IA-64,SMP]
2754 vector=percpu: enable percpu vector domain
2755
1da177e4
LT
2756 video= [FB] Frame buffer configuration
2757 See Documentation/fb/modedb.txt.
2758
cd4f0ef7 2759 vga= [BOOT,X86-32] Select a particular video mode
954a8b81 2760 See Documentation/x86/boot.txt and
a9913044 2761 Documentation/svga.txt.
1da177e4
LT
2762 Use vga=ask for menu.
2763 This is actually a boot loader parameter; the value is
2764 passed to the kernel using a special protocol.
2765
a9913044 2766 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2767 size of <nn>. This can be used to increase the
2768 minimum size (128MB on x86). It can also be used to
2769 decrease the size and leave more room for directly
2770 mapped kernel RAM.
2771
585c3047
PO
2772 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2773 Format: <command>
1da177e4 2774
585c3047
PO
2775 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2776 Format: <command>
2777
2778 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2779 Format: <command>
a9913044 2780
9ea9a886
CL
2781 vt.cur_default= [VT] Default cursor shape.
2782 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2783 the parameters of the <Esc>[?A;B;Cc escape sequence;
2784 see VGA-softcursor.txt. Default: 2 = underline.
2785
0cb55ad2
RD
2786 vt.default_blu= [VT]
2787 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2788 Change the default blue palette of the console.
2789 This is a 16-member array composed of values
2790 ranging from 0-255.
2791
2792 vt.default_grn= [VT]
2793 Format: <green0>,<green1>,<green2>,...,<green15>
2794 Change the default green palette of the console.
2795 This is a 16-member array composed of values
2796 ranging from 0-255.
2797
2798 vt.default_red= [VT]
2799 Format: <red0>,<red1>,<red2>,...,<red15>
2800 Change the default red palette of the console.
2801 This is a 16-member array composed of values
2802 ranging from 0-255.
2803
2804 vt.default_utf8=
2805 [VT]
2806 Format=<0|1>
2807 Set system-wide default UTF-8 mode for all tty's.
2808 Default is 1, i.e. UTF-8 mode is enabled for all
2809 newly opened terminals.
2810
f6c06b68
MG
2811 vt.global_cursor_default=
2812 [VT]
2813 Format=<-1|0|1>
2814 Set system-wide default for whether a cursor
2815 is shown on new VTs. Default is -1,
2816 i.e. cursors will be created by default unless
2817 overridden by individual drivers. 0 will hide
2818 cursors, 1 will display them.
2819
1da177e4
LT
2820 waveartist= [HW,OSS]
2821 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2822
1da177e4
LT
2823 wd33c93= [HW,SCSI]
2824 See header of drivers/scsi/wd33c93.c.
2825
2826 wd7000= [HW,SCSI]
2827 See header of drivers/scsi/wd7000.c.
2828
2829 wdt= [WDT] Watchdog
8dfe9c21 2830 See Documentation/watchdog/wdt.txt.
1da177e4 2831
0cb55ad2
RD
2832 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2833 default x2apic cluster mode on platforms
2834 supporting x2apic.
2835
bb24c471
JP
2836 x86_mrst_timer= [X86-32,APBT]
2837 Choose timer option for x86 Moorestown MID platform.
2838 Two valid options are apbt timer only and lapic timer
2839 plus one apbt timer for broadcast timer.
2840 x86_mrst_timer=apbt_only | lapic_and_apbt
2841
1da177e4
LT
2842 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2843 xd_geo= See header of drivers/block/xd.c.
2844
2845 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2846 Format:
2847 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2848
a9913044 2849______________________________________________________________________
1da177e4
LT
2850
2851TODO:
2852
2853 Add documentation for ALSA options.
2854 Add more DRM drivers.