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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
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3
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
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20Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
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26This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
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33The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
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37
38 ACPI ACPI support is enabled.
c99c108a 39 AGP AGP (Accelerated Graphics Port) is enabled.
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40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
e7ba176b 43 AVR32 AVR32 architecture is enabled.
1da177e4 44 AX25 Appropriate AX.25 support is enabled.
0ae53640 45 BLACKFIN Blackfin architecture is enabled.
a9913044 46 DRM Direct Rendering Management support is enabled.
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47 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
2521f2c2 51 GCOV GCOV profiling is enabled.
1da177e4 52 HW Appropriate hardware is enabled.
1da177e4 53 IA-64 IA-64 architecture is enabled.
6146f0d5 54 IMA Integrity measurement architecture is enabled.
1da177e4 55 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 56 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
b0f83b28 57 IPV6 IPv6 support is enabled.
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58 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
fef07aae 61 KVM Kernel Virtual Machine support is enabled.
11ef697b 62 LIBATA Libata driver is enabled
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63 LP Printer support is enabled.
64 LOOP Loopback device support is enabled.
65 M68k M68k architecture is enabled.
66 These options have more detailed description inside of
67 Documentation/m68k/kernel-options.txt.
68 MCA MCA bus support is enabled.
69 MDA MDA console support is enabled.
70 MOUSE Appropriate mouse support is enabled.
309e57df 71 MSI Message Signaled Interrupts (PCI).
c8facbb6 72 MTD MTD (Memory Technology Device) support is enabled.
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73 NET Appropriate network support is enabled.
74 NUMA NUMA support is enabled.
734efb46 75 GENERIC_TIME The generic timeofday code is enabled.
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76 NFS Appropriate NFS support is enabled.
77 OSS OSS sound support is enabled.
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78 PV_OPS A paravirtualized kernel is enabled.
79 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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80 PARISC The PA-RISC architecture is enabled.
81 PCI PCI bus support is enabled.
7f785763 82 PCIE PCI Express support is enabled.
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83 PCMCIA The PCMCIA subsystem is enabled.
84 PNP Plug & Play support is enabled.
85 PPC PowerPC architecture is enabled.
86 PPT Parallel port support is enabled.
87 PS2 Appropriate PS/2 support is enabled.
88 RAM RAM disk support is enabled.
89 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
92 Documentation/scsi/.
20510f2f 93 SECURITY Different security models are enabled.
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94 SELINUX SELinux support is enabled.
95 SERIAL Serial support is enabled.
e523d93c 96 SH SuperH architecture is enabled.
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97 SMP The kernel is an SMP kernel.
98 SPARC Sparc architecture is enabled.
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99 SWSUSP Software suspend (hibernation) is enabled.
100 SUSPEND System suspend states are enabled.
f38f1d2a 101 FTRACE Function tracing enabled.
1da177e4 102 TS Appropriate touchscreen support is enabled.
d4f373e5 103 UMS USB Mass Storage support is enabled.
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104 USB USB support is enabled.
105 USBHID USB Human Interface Device support is enabled.
106 V4L Video For Linux support is enabled.
107 VGA The VGA console has been enabled.
108 VT Virtual terminal support is enabled.
109 WDT Watchdog support is enabled.
110 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 111 X86-32 X86-32, aka i386 architecture is enabled.
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112 X86-64 X86-64 architecture is enabled.
113 More X86-64 boot options can be found in
71cced6e 114 Documentation/x86/x86_64/boot-options.txt .
c0115606 115 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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116
117In addition, the following text indicates that the option:
118
119 BUGS= Relates to possible processor bugs on the said processor.
120 KNL Is a kernel start-up parameter.
121 BOOT Is a boot loader parameter.
122
123Parameters denoted with BOOT are actually interpreted by the boot
124loader, and have no meaning to the kernel directly.
125Do not modify the syntax of boot loader parameters without extreme
954a8b81 126need or coordination with <Documentation/x86/boot.txt>.
1da177e4 127
5558870b 128There are also arch-specific kernel-parameters not documented here.
71cced6e 129See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 130
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131Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
132a trailing = on the name of any parameter states that that parameter will
133be entered as an environment variable, whereas its absence indicates that
134it will appear as a kernel argument readable via /proc/cmdline by programs
135running once the system is up.
136
9c4751fd 137The number of kernel parameters is not limited, but the length of the
138complete command line (parameters including spaces etc.) is limited to
139a fixed number of characters. This limit depends on the architecture
140and is between 256 and 4096 characters. It is defined in the file
141./include/asm/setup.h as COMMAND_LINE_SIZE.
142
143
6cececfc 144 acpi= [HW,ACPI,X86]
03d926f8 145 Advanced Configuration and Power Interface
af23f573 146 Format: { force | off | ht | strict | noirq | rsdt }
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147 force -- enable ACPI if default was off
148 off -- disable ACPI if default was on
149 noirq -- do not use ACPI for IRQ routing
150 ht -- run only enough ACPI to enable Hyper Threading
a9913044 151 strict -- Be less tolerant of platforms that are not
1da177e4 152 strictly ACPI specification compliant.
237889bf 153 rsdt -- prefer RSDT over (default) XSDT
1da177e4 154
53471121 155 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 156
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157 acpi_apic_instance= [ACPI, IOAPIC]
158 Format: <int>
159 2: use 2nd APIC table, if available
160 1,0: use 1st APIC table
4e381a4f 161 default: 0
a1fdcc0d 162
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163 acpi_backlight= [HW,ACPI]
164 acpi_backlight=vendor
165 acpi_backlight=video
166 If set to vendor, prefer vendor specific driver
167 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
168 of the ACPI video.ko driver.
169
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170 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
171 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 172 Format: <int>
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173 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
174 debug output. Bits in debug_layer correspond to a
175 _COMPONENT in an ACPI source file, e.g.,
176 #define _COMPONENT ACPI_PCI_COMPONENT
177 Bits in debug_level correspond to a level in
178 ACPI_DEBUG_PRINT statements, e.g.,
179 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
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180 The debug_level mask defaults to "info". See
181 Documentation/acpi/debug.txt for more information about
182 debug layers and levels.
a0d84a92 183
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184 Enable processor driver info messages:
185 acpi.debug_layer=0x20000000
186 Enable PCI/PCI interrupt routing info messages:
187 acpi.debug_layer=0x400000
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188 Enable AML "Debug" output, i.e., stores to the Debug
189 object while interpreting AML:
190 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
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191 Enable all messages related to ACPI hardware:
192 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
193
194 Some values produce so much output that the system is
195 unusable. The "log_buf_len" parameter may be useful
196 if you need to capture more output.
f989106c 197
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198 acpi_display_output= [HW,ACPI]
199 acpi_display_output=vendor
200 acpi_display_output=video
201 See above.
202
203 acpi_irq_balance [HW,ACPI]
204 ACPI will balance active IRQs
205 default in APIC mode
206
207 acpi_irq_nobalance [HW,ACPI]
208 ACPI will not move active IRQs (default)
209 default in PIC mode
210
211 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
212 Format: <irq>,<irq>...
213
214 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
215 use by PCI
216 Format: <irq>,<irq>...
217
218 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
219
220 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
221 Format: To spoof as Windows 98: ="Microsoft Windows"
222
223 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
224 acpi_osi="string1" # add string1 -- only one string
225 acpi_osi="!string2" # remove built-in string2
226 acpi_osi= # disable all strings
227
6cececfc 228 acpi_pm_good [X86]
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229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
232
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233 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
234 Format: { level | edge | high | low }
235
236 acpi_serialize [HW,ACPI] force serialization of AML methods
237
238 acpi_skip_timer_override [HW,ACPI]
239 Recognize and ignore IRQ0/pin2 Interrupt Override.
240 For broken nForce2 BIOS resulting in XT-PIC timer.
241
242 acpi_sleep= [HW,ACPI] Sleep options
243 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
d7f0eea9 244 old_ordering, s4_nonvs, sci_force_enable }
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245 See Documentation/power/video.txt for information on
246 s3_bios and s3_mode.
247 s3_beep is for debugging; it makes the PC's speaker beep
248 as soon as the kernel's real-mode entry point is called.
249 s4_nohwsig prevents ACPI hardware signature from being
250 used during resume from hibernation.
251 old_ordering causes the ACPI 1.0 ordering of the _PTS
252 control method, with respect to putting devices into
253 low power states, to be enforced (the ACPI 2.0 ordering
254 of _PTS is used by default).
255 s4_nonvs prevents the kernel from saving/restoring the
256 ACPI NVS memory during hibernation.
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257 sci_force_enable causes the kernel to set SCI_EN directly
258 on resume from S1/S3 (which is against the ACPI spec,
259 but some broken systems don't work without it).
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260
261 acpi_use_timer_override [HW,ACPI]
262 Use timer override. For some broken Nvidia NF5 boards
263 that require a timer override, but don't have HPET
264
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265 acpi_enforce_resources= [ACPI]
266 { strict | lax | no }
267 Check for resource conflicts between native drivers
268 and ACPI OperationRegions (SystemIO and SystemMemory
269 only). IO ports and memory declared in ACPI might be
270 used by the ACPI subsystem in arbitrary AML code and
271 can interfere with legacy drivers.
272 strict (default): access to resources claimed by ACPI
273 is denied; legacy drivers trying to access reserved
274 resources will fail to bind to device using them.
275 lax: access to resources claimed by ACPI is allowed;
276 legacy drivers trying to access reserved resources
277 will bind successfully but a warning message is logged.
278 no: ACPI OperationRegions are not marked as reserved,
279 no further checks are performed.
280
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281 ad1848= [HW,OSS]
282 Format: <io>,<irq>,<dma>,<dma2>,<type>
283
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284 add_efi_memmap [EFI; X86] Include EFI memory map in
285 kernel's map of available physical RAM.
286
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287 advansys= [HW,SCSI]
288 See header of drivers/scsi/advansys.c.
289
290 advwdt= [HW,WDT] Advantech WDT
291 Format: <iostart>,<iostop>
292
293 aedsp16= [HW,OSS] Audio Excel DSP 16
294 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
295 See also header of sound/oss/aedsp16.c.
a9913044 296
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297 agp= [AGP]
298 { off | try_unsupported }
299 off: disable AGP support
300 try_unsupported: try to drive unsupported chipsets
301 (may crash computer or cause data corruption)
302
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303 aha152x= [HW,SCSI]
304 See Documentation/scsi/aha152x.txt.
305
306 aha1542= [HW,SCSI]
307 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
308
309 aic7xxx= [HW,SCSI]
310 See Documentation/scsi/aic7xxx.txt.
311
312 aic79xx= [HW,SCSI]
313 See Documentation/scsi/aic79xx.txt.
314
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315 amd_iommu= [HW,X86-84]
316 Pass parameters to the AMD IOMMU driver in the system.
317 Possible values are:
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318 isolate - enable device isolation (each device, as far
319 as possible, will get its own protection
3ce1f93c 320 domain) [default]
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321 share - put every device behind one IOMMU into the
322 same protection domain
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323 fullflush - enable flushing of IO/TLB entries when
324 they are unmapped. Otherwise they are
325 flushed before they will be reused, which
326 is a lot of faster
327
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328 amijoy.map= [HW,JOY] Amiga joystick support
329 Map of devices attached to JOY0DAT and JOY1DAT
330 Format: <a>,<b>
331 See also Documentation/kernel/input/joystick.txt
332
333 analog.map= [HW,JOY] Analog joystick and gamepad support
334 Specifies type or capabilities of an analog joystick
335 connected to one of 16 gameports
336 Format: <type1>,<type2>,..<type16>
337
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338 apc= [HW,SPARC]
339 Power management functions (SPARCstation-4/5 + deriv.)
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340 Format: noidle
341 Disable APC CPU standby support. SPARCstation-Fox does
342 not play well with APC CPU idle - disable it if you have
343 APC and your system crashes randomly.
344
ca1eda2d 345 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
c8facbb6 346 Change the output verbosity whilst booting
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347 Format: { quiet (default) | verbose | debug }
348 Change the amount of debugging information output
349 when initialising the APIC and IO-APIC components.
a9913044 350
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351 autoconf= [IPV6]
352 See Documentation/networking/ipv6.txt.
353
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354 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
355 Limit apic dumping. The parameter defines the maximal
356 number of local apics being dumped. Also it is possible
357 to set it to "all" by meaning -- no limit here.
358 Format: { 1 (default) | 2 | ... | all }.
359 The parameter valid if only apic=debug or
360 apic=verbose is specified.
361 Example: apic=debug show_lapic=all
362
1da177e4 363 apm= [APM] Advanced Power Management
71f77055 364 See header of arch/x86/kernel/apm_32.c.
1da177e4 365
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366 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
367 Format: <io>,<irq>,<nodeID>
368
369 ataflop= [HW,M68k]
370
371 atarimouse= [HW,MOUSE] Atari Mouse
372
373 atascsi= [HW,SCSI] Atari SCSI
374
375 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
376 EzKey and similar keyboards
377
378 atkbd.reset= [HW] Reset keyboard during initialization
379
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380 atkbd.set= [HW] Select keyboard code set
381 Format: <int> (2 = AT (default), 3 = PS/2)
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382
383 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
384 keyboards
385
386 atkbd.softraw= [HW] Choose between synthetic and real raw mode
387 Format: <bool> (0 = real, 1 = synthetic (default))
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388
389 atkbd.softrepeat= [HW]
390 Use software keyboard repeat
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391
392 autotest [IA64]
393
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394 baycom_epp= [HW,AX25]
395 Format: <io>,<mode>
a9913044 396
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397 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
398 Format: <io>,<mode>
399 See header of drivers/net/hamradio/baycom_par.c.
400
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401 baycom_ser_fdx= [HW,AX25]
402 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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403 Format: <io>,<irq>,<mode>[,<baud>]
404 See header of drivers/net/hamradio/baycom_ser_fdx.c.
405
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406 baycom_ser_hdx= [HW,AX25]
407 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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408 Format: <io>,<irq>,<mode>
409 See header of drivers/net/hamradio/baycom_ser_hdx.c.
410
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411 boot_delay= Milliseconds to delay each printk during boot.
412 Values larger than 10 seconds (10000) are changed to
413 no delay (0).
414 Format: integer
415
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416 bootmem_debug [KNL] Enable bootmem allocator debug messages.
417
1da177e4 418 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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419 bttv.radio= Most important insmod options are available as
420 kernel args too.
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421 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
422 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
423
424 BusLogic= [HW,SCSI]
425 See drivers/scsi/BusLogic.c, comment before function
426 BusLogic_ParseDriverOptions().
427
428 c101= [NET] Moxa C101 synchronous serial card
429
cd4f0ef7 430 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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431 Sometimes CPU hardware bugs make them report the cache
432 size incorrectly. The kernel will attempt work arounds
433 to fix known problems, but for some CPUs it is not
434 possible to determine what the correct size should be.
435 This option provides an override for these situations.
436
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437 capability.disable=
438 [SECURITY] Disable capabilities. This would normally
439 be used only if an alternative security model is to be
440 configured. Potentially dangerous and should only be
441 used if you are entirely sure of the consequences.
442
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443 ccw_timeout_log [S390]
444 See Documentation/s390/CommonIO for details.
1da177e4 445
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446 cgroup_disable= [KNL] Disable a particular controller
447 Format: {name of the controller(s) to disable}
448 {Currently supported controllers - "memory"}
449
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450 checkreqprot [SELINUX] Set initial checkreqprot flag value.
451 Format: { "0" | "1" }
452 See security/selinux/Kconfig help text.
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453 0 -- check protection applied by kernel (includes
454 any implied execute protection).
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455 1 -- check protection requested by application.
456 Default value is set via a kernel config option.
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457 Value can be changed at runtime via
458 /selinux/checkreqprot.
459
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460 cio_ignore= [S390]
461 See Documentation/s390/CommonIO for details.
462
cd4f0ef7 463 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 464 [Deprecated]
3f6dee9b 465 Forces specified clocksource (if available) to be used
734efb46 466 when calculating gettimeofday(). If specified
3f6dee9b 467 clocksource is not available, it defaults to PIT.
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468 Format: { pit | tsc | cyclone | pmtmr }
469
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470 clocksource= [GENERIC_TIME] Override the default clocksource
471 Format: <string>
472 Override the default clocksource and use the clocksource
473 with the name specified.
474 Some clocksource names to choose from, depending on
475 the platform:
476 [all] jiffies (this is the base, fallback clocksource)
477 [ACPI] acpi_pm
478 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
479 pxa_timer,timer3,32k_counter,timer0_1
480 [AVR32] avr32
cd4f0ef7 481 [X86-32] pit,hpet,tsc,vmi-timer;
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482 scx200_hrt on Geode; cyclone on IBM x440
483 [MIPS] MIPS
484 [PARISC] cr16
485 [S390] tod
486 [SH] SuperH
487 [SPARC64] tick
488 [X86-64] hpet,tsc
489
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490 clearcpuid=BITNUM [X86]
491 Disable CPUID feature X for the kernel. See
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492 arch/x86/include/asm/cpufeature.h for the valid bit
493 numbers. Note the Linux specific bits are not necessarily
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494 stable over kernel options, but the vendor specific
495 ones should be.
496 Also note that user programs calling CPUID directly
497 or using the feature without checking anything
498 will still see it. This just prevents it from
499 being used by the kernel or shown in /proc/cpuinfo.
500 Also note the kernel might malfunction if you disable
501 some critical bits.
502
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503 cmo_free_hint= [PPC] Format: { yes | no }
504 Specify whether pages are marked as being inactive
505 when they are freed. This is used in CMO environments
506 to determine OS memory pressure for page stealing by
507 a hypervisor.
508 Default: yes
509
6cececfc 510 code_bytes [X86] How many bytes of object code to print
a25bd949 511 in an oops report.
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512 Range: 0 - 8192
513 Default: 64
514
1da177e4 515 com20020= [HW,NET] ARCnet - COM20020 chipset
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516 Format:
517 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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518
519 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
520 Format: <io>[,<irq>]
521
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522 com90xx= [HW,NET]
523 ARCnet - COM90xx chipset (memory-mapped buffers)
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524 Format: <io>[,<irq>[,<memstart>]]
525
526 condev= [HW,S390] console device
527 conmode=
a9913044 528
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LT
529 console= [KNL] Output console device and options.
530
531 tty<n> Use the virtual console device <n>.
532
533 ttyS<n>[,options]
f1a1c2dc 534 ttyUSB0[,options]
1da177e4 535 Use the specified serial port. The options are of
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RD
536 the form "bbbbpnf", where "bbbb" is the baud rate,
537 "p" is parity ("n", "o", or "e"), "n" is number of
538 bits, and "f" is flow control ("r" for RTS or
539 omit it). Default is "9600n8".
540
541 See Documentation/serial-console.txt for more
542 information. See
543 Documentation/networking/netconsole.txt for an
544 alternative.
1da177e4 545
18a8bd94
YL
546 uart[8250],io,<addr>[,options]
547 uart[8250],mmio,<addr>[,options]
1da177e4
LT
548 Start an early, polled-mode console on the 8250/16550
549 UART at the specified I/O port or MMIO address,
550 switching to the matching ttyS device later. The
551 options are the same as for ttyS, above.
552
f7511d5f
ST
553 If the device connected to the port is not a TTY but a braille
554 device, prepend "brl," before the device type, for instance
555 console=brl,ttyS0
556 For now, only VisioBraille is supported.
557
f324edc8
DM
558 consoleblank= [KNL] The console blank (screen saver) timeout in
559 seconds. Defaults to 10*60 = 10mins. A value of 0
560 disables the blank timer.
561
4cb0e11b
HK
562 coredump_filter=
563 [KNL] Change the default value for
564 /proc/<pid>/coredump_filter.
565 See also Documentation/filesystems/proc.txt.
566
1da177e4 567 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
568 Format:
569 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 570
dc009d92
EB
571 crashkernel=nn[KMG]@ss[KMG]
572 [KNL] Reserve a chunk of physical memory to
573 hold a kernel to switch to with kexec on panic.
574
fb391599
BW
575 crashkernel=range1:size1[,range2:size2,...][@offset]
576 [KNL] Same as above, but depends on the memory
577 in the running system. The syntax of range is
578 start-[end] where start and end are both
579 a memory unit (amount[KMG]). See also
580 Documentation/kdump/kdump.txt for a example.
581
1da177e4
LT
582 cs89x0_dma= [HW,NET]
583 Format: <dma>
584
585 cs89x0_media= [HW,NET]
586 Format: { rj45 | aui | bnc }
a9913044 587
a9913044 588 dasd= [HW,NET]
1da177e4
LT
589 See header of drivers/s390/block/dasd_devmap.c.
590
591 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
592 (one device per port)
593 Format: <port#>,<type>
594 See also Documentation/input/joystick-parport.txt
595
596 debug [KNL] Enable kernel debugging (events log level).
597
cae2ed9a
IM
598 debug_locks_verbose=
599 [KNL] verbose self-tests
600 Format=<0|1>
601 Print debugging info while doing the locking API
602 self-tests.
603 We default to 0 (no extra messages), setting it to
604 1 will print _a lot_ more information - normally
605 only useful to kernel developers.
606
3ac7fe5a
TG
607 debug_objects [KNL] Enable object debugging
608
3e8ebb5c
KM
609 no_debug_objects
610 [KNL] Disable object debugging
611
d3af01f1
TG
612 debugpat [X86] Enable PAT debugging
613
2d27a966 614 decnet.addr= [HW,NET]
1da177e4
LT
615 Format: <area>[,<node>]
616 See also Documentation/networking/decnet.txt.
617
0cb55ad2
RD
618 default_hugepagesz=
619 [same as hugepagesz=] The size of the default
620 HugeTLB page size. This is the size represented by
621 the legacy /proc/ hugepages APIs, used for SHM, and
622 default size when mounting hugetlbfs filesystems.
623 Defaults to the default architecture's huge page size
624 if not specified.
55ff9780 625
1da177e4
LT
626 dhash_entries= [KNL]
627 Set number of hash buckets for dentry cache.
a9913044 628
1da177e4
LT
629 digi= [HW,SERIAL]
630 IO parameters + enable/disable command.
631
632 digiepca= [HW,SERIAL]
633 See drivers/char/README.epca and
31c00fc1 634 Documentation/serial/digiepca.txt.
1da177e4 635
b0f83b28
BH
636 disable= [IPV6]
637 See Documentation/networking/ipv6.txt.
638
639 disable_ipv6= [IPV6]
640 See Documentation/networking/ipv6.txt.
641
95ffa243 642 disable_mtrr_cleanup [X86]
95ffa243
YL
643 The kernel tries to adjust MTRR layout from continuous
644 to discrete, to make X server driver able to add WB
0cb55ad2 645 entry later. This parameter disables that.
95ffa243 646
093af8d7 647 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
652
6cececfc 653 disable_timer_pin_1 [X86]
0cb55ad2
RD
654 Disable PIN 1 of APIC timer
655 Can be useful to work around chipset bugs.
656
1da177e4
LT
657 dmasound= [HW,OSS] Sound subsystem buffers
658
0cb55ad2
RD
659 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
660 this option disables the debugging code at boot.
661
662 dma_debug_entries=<number>
663 This option allows to tune the number of preallocated
664 entries for DMA-API debugging code. One entry is
665 required per DMA-API allocation. Use this if the
666 DMA-API debugging code disables itself because the
667 architectural default is too low.
668
1745de5e
JR
669 dma_debug_driver=<driver_name>
670 With this option the DMA-API debugging driver
671 filter feature can be enabled at boot time. Just
672 pass the driver to filter for as the parameter.
673 The filter can be disabled or changed to another
674 driver later using sysfs.
675
1da177e4
LT
676 dscc4.setup= [NET]
677
678 dtc3181e= [HW,SCSI]
679
0cb55ad2
RD
680 dynamic_printk Enables pr_debug()/dev_dbg() calls if
681 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
682 These can also be switched on/off via
683 <debugfs>/dynamic_printk/modules
684
685 earlycon= [KNL] Output early console device and options.
686 uart[8250],io,<addr>[,options]
687 uart[8250],mmio,<addr>[,options]
688 Start an early, polled-mode console on the 8250/16550
689 UART at the specified I/O port or MMIO address.
690 The options are the same as for ttyS, above.
691
6cececfc 692 earlyprintk= [X86,SH,BLACKFIN]
1da177e4
LT
693 earlyprintk=vga
694 earlyprintk=serial[,ttySn[,baudrate]]
ea3acb19 695 earlyprintk=ttySn[,baudrate]
9780bc41 696 earlyprintk=dbgp[debugController#]
1da177e4 697
a9913044 698 Append ",keep" to not disable it when the real console
1da177e4
LT
699 takes over.
700
5c05917e 701 Only vga or serial or usb debug port at a time.
1da177e4
LT
702
703 Currently only ttyS0 and ttyS1 are supported.
704
705 Interaction with the standard serial driver is not
706 very good.
707
708 The VGA output is eventually overwritten by the real
709 console.
710
711 eata= [HW,SCSI]
712
1da177e4 713 edd= [EDD]
8c4dd606 714 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 715
1da177e4
LT
716 eisa_irq_edge= [PARISC,HW]
717 See header of drivers/parisc/eisa.c.
718
cd4f0ef7 719 elanfreq= [X86-32]
1da177e4 720 See comment before function elanfreq_setup() in
71f77055 721 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
722
723 elevator= [IOSCHED]
16ab3adf 724 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
725 See Documentation/block/as-iosched.txt and
726 Documentation/block/deadline-iosched.txt for details.
727
6cececfc 728 elfcorehdr= [IA64,PPC,SH,X86]
a9913044 729 Specifies physical address of start of kernel core
aac04b32
VG
730 image elf header. Generally kexec loader will
731 pass this option to capture kernel.
732 See Documentation/kdump/kdump.txt for details.
1da177e4 733
0cb55ad2
RD
734 enable_mtrr_cleanup [X86]
735 The kernel tries to adjust MTRR layout from continuous
736 to discrete, to make X server driver able to add WB
737 entry later. This parameter enables that.
738
ca1eda2d 739 enable_timer_pin_1 [X86]
0cb55ad2
RD
740 Enable PIN 1 of APIC timer
741 Can be useful to work around chipset bugs
742 (in particular on some ATI chipsets).
743 The kernel tries to set a reasonable default.
744
1da177e4
LT
745 enforcing [SELINUX] Set initial enforcing status.
746 Format: {"0" | "1"}
747 See security/selinux/Kconfig help text.
748 0 -- permissive (log only, no denials).
749 1 -- enforcing (deny and log).
750 Default value is 0.
751 Value can be changed at runtime via /selinux/enforce.
752
1da177e4
LT
753 ether= [HW,NET] Ethernet cards parameters
754 This option is obsoleted by the "netdev=" option, which
755 has equivalent usage. See its documentation for details.
756
757 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
758 Format: <io>[,<irq>]
759
de1ba09b
AM
760 failslab=
761 fail_page_alloc=
762 fail_make_request=[KNL]
763 General fault injection mechanism.
764 Format: <interval>,<probability>,<space>,<times>
765 See also /Documentation/fault-injection/.
766
1da177e4
LT
767 fd_mcs= [HW,SCSI]
768 See header of drivers/scsi/fd_mcs.c.
769
770 fdomain= [HW,SCSI]
771 See header of drivers/scsi/fdomain.c.
772
773 floppy= [HW]
31c00fc1 774 See Documentation/blockdev/floppy.txt.
1da177e4 775
f13ae30e
AC
776 force_pal_cache_flush
777 [IA-64] Avoid check_sal_cache_flush which may hang on
778 buggy SAL_CACHE_FLUSH implementations. Using this
779 parameter will force ia64_sal_cache_flush to call
780 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
781
d9e54076 782 ftrace=[tracer]
2af15d6a 783 [FTRACE] will set and start the specified tracer
d9e54076
PZ
784 as early as possible in order to facilitate early
785 boot debugging.
786
787 ftrace_dump_on_oops
2af15d6a
SR
788 [FTRACE] will dump the trace buffers on oops.
789
790 ftrace_filter=[function-list]
791 [FTRACE] Limit the functions traced by the function
792 tracer at boot up. function-list is a comma separated
793 list of functions. This list can be changed at run
794 time by the set_ftrace_filter file in the debugfs
795 tracing directory.
796
797 ftrace_notrace=[function-list]
798 [FTRACE] Do not trace the functions specified in
799 function-list. This list can be changed at run time
800 by the set_ftrace_notrace file in the debugfs
801 tracing directory.
d9e54076 802
369bc18f
SA
803 ftrace_graph_filter=[function-list]
804 [FTRACE] Limit the top level callers functions traced
805 by the function graph tracer at boot up.
806 function-list is a comma separated list of functions
807 that can be changed at run time by the
808 set_graph_function file in the debugfs tracing directory.
809
1da177e4
LT
810 gamecon.map[2|3]=
811 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
812 support via parallel port (up to 5 devices per port)
813 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
814 See also Documentation/input/joystick-parport.txt
815
816 gamma= [HW,DRM]
817
aaf23042
YL
818 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
819 Format: off | on
820 default: on
821
2521f2c2
PO
822 gcov_persist= [GCOV] When non-zero (default), profiling data for
823 kernel modules is saved and remains accessible via
824 debugfs, even when the module is unloaded/reloaded.
825 When zero, profiling data is discarded and associated
826 debugfs files are removed at module unload time.
827
1da177e4
LT
828 gdth= [HW,SCSI]
829 See header of drivers/scsi/gdth.c.
830
831 gpt [EFI] Forces disk with valid GPT signature but
832 invalid Protective MBR to be treated as GPT.
833
1da177e4
LT
834 gvp11= [HW,SCSI]
835
836 hashdist= [KNL,NUMA] Large hashes allocated during boot
837 are distributed across NUMA nodes. Defaults on
429aa0fc 838 for 64bit NUMA, off otherwise.
a9913044 839 Format: 0 | 1 (for off | on)
1da177e4
LT
840
841 hcl= [IA-64] SGI's Hardware Graph compatibility layer
842
843 hd= [EIDE] (E)IDE hard drive subsystem geometry
844 Format: <cyl>,<head>,<sect>
845
1da177e4
LT
846 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
847 size of <nn>. This works even on boxes that have no
848 highmem otherwise. This also works to reduce highmem
849 size on bigger boxes.
850
54cdfdb4
TG
851 highres= [KNL] Enable/disable high resolution timer mode.
852 Valid parameters: "on", "off"
853 Default: "on"
854
1da177e4
LT
855 hisax= [HW,ISDN]
856 See Documentation/isdn/README.HiSax.
857
0cb55ad2
RD
858 hlt [BUGS=ARM,SH]
859
860 hpet= [X86-32,HPET] option to control HPET usage
861 Format: { enable (default) | disable | force |
862 verbose }
863 disable: disable HPET and use PIT instead
864 force: allow force enabled of undocumented chips (ICH4,
865 VIA, nVidia)
866 verbose: show contents of HPET registers during setup
867
b4718e62
AK
868 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
869 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
870 On x86-64 and powerpc, this option can be specified
871 multiple times interleaved with hugepages= to reserve
872 huge pages of different sizes. Valid pages sizes on
873 x86-64 are 2M (when the CPU supports "pse") and 1G
874 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
875 Note that 1GB pages can only be allocated at boot time
876 using hugepages= and not freed afterwards.
6902aa84 877
555d61d6
HB
878 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
879 terminal devices. Valid values: 0..8
431429ff
HB
880 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
881 If specified, z/VM IUCV HVC accepts connections
882 from listed z/VM user IDs only.
cef7125d 883
3a853fb9 884 i2c_bus= [HW] Override the default board specific I2C bus speed
7954763b
JN
885 or register an additional I2C bus that is not
886 registered from board initialization code.
3a853fb9
JN
887 Format:
888 <bus_id>,<clkrate>
889
36d95739 890 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 891 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
892 i8042.dumbkbd [HW] Pretend that controller can only read data from
893 keyboard and cannot control its state
1da177e4
LT
894 (Don't attempt to blink the leds)
895 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 896 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
897 i8042.noloop [HW] Disable the AUX Loopback command while probing
898 for the AUX port
1da177e4
LT
899 i8042.nomux [HW] Don't check presence of an active multiplexing
900 controller
901 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
902 controllers
903 i8042.panicblink=
904 [HW] Frequency with which keyboard LEDs should blink
905 when kernel panics (default is 0.5 sec)
906 i8042.reset [HW] Reset the controller during init and cleanup
907 i8042.unlock [HW] Unlock (ignore) the keylock
908
909 i810= [HW,DRM]
910
e70c9d5e
DT
911 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
912 indicates that the driver is running on unsupported
913 hardware.
1da177e4
LT
914 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
915 does not match list of supported models.
916 i8k.power_status
917 [HW] Report power status in /proc/i8k
918 (disabled by default)
919 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
920 capability is set.
921
922 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
923 See Documentation/mca.txt.
924
925 icn= [HW,ISDN]
926 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
927
0af80c04
DF
928 ide-core.nodma= [HW] (E)IDE subsystem
929 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
075affcb
BZ
930 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
931 .cdrom .chs .ignore_cable are additional options
1c10e938 932 See Documentation/ide/ide.txt.
1da177e4 933
0cb55ad2
RD
934 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
935 Claim all unknown PCI IDE storage controllers.
936
f039b754 937 idle= [X86]
ada9cfdd
RD
938 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
939 Poll forces a polling idle loop that can slightly
940 improve the performance of waking up a idle CPU, but
941 will use a lot of power and make the system run hot.
942 Not recommended.
943 idle=mwait: On systems which support MONITOR/MWAIT but
944 the kernel chose to not use it because it doesn't save
945 as much power as a normal idle loop, use the
946 MONITOR/MWAIT idle loop anyways. Performance should be
947 the same as idle=poll.
948 idle=halt: Halt is forced to be used for CPU idle.
c1e3b377 949 In such case C2/C3 won't be used again.
ada9cfdd 950 idle=nomwait: Disable mwait for CPU C-states
a9913044 951
79290822
IM
952 ignore_loglevel [KNL]
953 Ignore loglevel setting - this will print /all/
954 kernel messages to the console. Useful for debugging.
955
1da177e4
LT
956 ihash_entries= [KNL]
957 Set number of hash buckets for inode cache.
958
3323eec9
MZ
959 ima_audit= [IMA]
960 Format: { "0" | "1" }
961 0 -- integrity auditing messages. (Default)
962 1 -- enable informational integrity auditing messages.
963
964 ima_hash= [IMA]
a9ed83a5 965 Format: { "sha1" | "md5" }
3323eec9
MZ
966 default: "sha1"
967
5789ba3b
EP
968 ima_tcb [IMA]
969 Load a policy which meets the needs of the Trusted
970 Computing Base. This means IMA will measure all
971 programs exec'd, files mmap'd for exec, and all files
972 opened for read by uid=0.
973
1da177e4
LT
974 in2000= [HW,SCSI]
975 See header of drivers/scsi/in2000.c.
976
977 init= [KNL]
978 Format: <full_path>
979 Run specified binary instead of /sbin/init as init
980 process.
981
982 initcall_debug [KNL] Trace initcalls as they are executed. Useful
983 for working out where the kernel is dying during
984 startup.
985
986 initrd= [BOOT] Specify the location of the initial ramdisk
987
988 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
989 Format: <irq>
990
ba395927 991 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
0cd5c3c8
KM
992 on
993 Enable intel iommu driver.
ba395927
KA
994 off
995 Disable intel iommu driver.
996 igfx_off [Default Off]
997 By default, gfx is mapped as normal device. If a gfx
998 device has a dedicated DMAR unit, the DMAR unit is
999 bypassed by not enabling DMAR with this option. In
1000 this case, gfx device will use physical address for
1001 DMA.
7d3b03ce
KA
1002 forcedac [x86_64]
1003 With this option iommu will not optimize to look
1004 for io virtual address below 32 bit forcing dual
1005 address cycle on pci bus for cards supporting greater
1006 than 32 bit addressing. The default is to look
1007 for translation below 32 bit and if not available
1008 then look in the higher range.
5e0d2a6f 1009 strict [Default Off]
1010 With this option on every unmap_single operation will
1011 result in a hardware IOTLB flush operation as opposed
1012 to batching them for performance.
ba395927 1013
0cb55ad2
RD
1014 inttest= [IA64]
1015
1016 iomem= Disable strict checking of access to MMIO memory
1017 strict regions from userspace.
1018 relaxed
1019
1020 iommu= [x86]
1021 off
1022 force
1023 noforce
1024 biomerge
1025 panic
1026 nopanic
1027 merge
1028 nomerge
1029 forcesac
1030 soft
4ed0d3e6 1031 pt [x86, IA64]
0cb55ad2
RD
1032
1033 io7= [HW] IO7 for Marvel based alpha systems
1034 See comment before marvel_specify_io7 in
1035 arch/alpha/kernel/core_marvel.c.
1036
6cececfc 1037 io_delay= [X86] I/O delay method
6e7c4025
IM
1038 0x80
1039 Standard port 0x80 based delay
1040 0xed
1041 Alternate port 0xed based delay (needed on some systems)
b02aae9c 1042 udelay
6e7c4025
IM
1043 Simple two microseconds delay
1044 none
1045 No delay
b02aae9c 1046
1da177e4 1047 ip= [IP_PNP]
dc7a0816 1048 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1049
1050 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
1051 See comment before ip2_setup() in
1052 drivers/char/ip2/ip2base.c.
1da177e4
LT
1053
1054 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1055 See header of drivers/scsi/ips.c.
1056
200803df
AC
1057 irqfixup [HW]
1058 When an interrupt is not handled search all handlers
1059 for it. Intended to get systems with badly broken
1060 firmware running.
1061
1062 irqpoll [HW]
1063 When an interrupt is not handled search all handlers
1064 for it. Also check all handlers each timer
1065 interrupt. Intended to get systems with badly broken
1066 firmware running.
1067
1da177e4 1068 isapnp= [ISAPNP]
a9913044 1069 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
1070
1071 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
1072 Format:
1073 <cpu number>,...,<cpu number>
1074 or
b225d44e
LZ
1075 <cpu number>-<cpu number>
1076 (must be a positive range in ascending order)
22f2e280
DF
1077 or a mixture
1078 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 1079
1da177e4
LT
1080 This option can be used to specify one or more CPUs
1081 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
1082 algorithms. You can move a process onto or off an
1083 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
1084 <cpu number> begins at 0 and the maximum value is
1085 "number of CPUs in system - 1".
1086
1087 This option is the preferred way to isolate CPUs. The
a9913044
RD
1088 alternative -- manually setting the CPU mask of all
1089 tasks in the system -- can cause problems and
1090 suboptimal load balancer performance.
1da177e4 1091
a9913044 1092 iucv= [HW,NET]
1da177e4
LT
1093
1094 js= [HW,JOY] Analog joystick
1095 See Documentation/input/joystick.txt.
1096
0cb55ad2
RD
1097 keepinitrd [HW,ARM]
1098
6cececfc 1099 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
ed7ed365
MG
1100 specifies the amount of memory usable by the kernel
1101 for non-movable allocations. The requested amount is
1102 spread evenly throughout all nodes in the system. The
1103 remaining memory in each node is used for Movable
1104 pages. In the event, a node is too small to have both
1105 kernelcore and Movable pages, kernelcore pages will
1106 take priority and other nodes will have a larger number
1107 of kernelcore pages. The Movable zone is used for the
1108 allocation of pages that may be reclaimed or moved
1109 by the page migration subsystem. This means that
1110 HugeTLB pages may not be allocated from this zone.
1111 Note that allocations like PTEs-from-HighMem still
1112 use the HighMem zone if it exists, and the Normal
1113 zone if it does not.
1114
6cdf6e06
JW
1115 kgdboc= [HW] kgdb over consoles.
1116 Requires a tty driver that supports console polling.
19f59460 1117 (only serial supported for now)
6cdf6e06
JW
1118 Format: <serial_device>[,baud]
1119
9bed90c6
FF
1120 kmac= [MIPS] korina ethernet MAC address.
1121 Configure the RouterBoard 532 series on-chip
1122 Ethernet adapter MAC address.
1123
04f70336
CM
1124 kmemleak= [KNL] Boot-time kmemleak enable/disable
1125 Valid arguments: on, off
1126 Default: on
1127
6cececfc 1128 kstack=N [X86] Print N words from the kernel stack
0cb55ad2
RD
1129 in oops dumps.
1130
fef07aae
AP
1131 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1132 Default is 0 (don't ignore, but inject #GP)
1133
1134 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1135 Default is 1 (enabled)
1136
1137 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1138 Default is 0 (off)
1139
1140 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1141 for all guests.
1142 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1143
1144 kvm-intel.bypass_guest_pf=
1145 [KVM,Intel] Disables bypassing of guest page faults
1146 on Intel chips. Default is 1 (enabled)
1147
1148 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1149 (virtualized MMU) support on capable Intel chips.
1150 Default is 1 (enabled)
1151
1152 kvm-intel.emulate_invalid_guest_state=
1153 [KVM,Intel] Enable emulation of invalid guest states
1154 Default is 0 (disabled)
1155
1156 kvm-intel.flexpriority=
1157 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1158 Default is 1 (enabled)
1159
1160 kvm-intel.unrestricted_guest=
1161 [KVM,Intel] Disable unrestricted guest feature
1162 (virtualized real and unpaged mode) on capable
1163 Intel chips. Default is 1 (enabled)
1164
1165 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1166 feature (tagged TLBs) on capable Intel chips.
1167 Default is 1 (enabled)
1168
1da177e4
LT
1169 l2cr= [PPC]
1170
a78bfbfc
RB
1171 l3cr= [PPC]
1172
cd4f0ef7 1173 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1174 disabled it.
1da177e4 1175
6cececfc 1176 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
ada9cfdd 1177 in C2 power state.
e585bef8 1178
fcb71f6f
FC
1179 libata.dma= [LIBATA] DMA control
1180 libata.dma=0 Disable all PATA and SATA DMA
1181 libata.dma=1 PATA and SATA Disk DMA only
1182 libata.dma=2 ATAPI (CDROM) DMA only
1183 libata.dma=4 Compact Flash DMA only
1184 Combinations also work, so libata.dma=3 enables DMA
1185 for disks and CDROMs, but not CFs.
20308871
MP
1186
1187 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1188 libata.ignore_hpa=0 keep BIOS limits (default)
1189 libata.ignore_hpa=1 ignore limits, using full disk
fcb71f6f 1190
78e70c23
DJ
1191 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1192 when set.
1193 Format: <int>
1194
33267325
TH
1195 libata.force= [LIBATA] Force configurations. The format is comma
1196 separated list of "[ID:]VAL" where ID is
1197 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1198 matching port, link or device. Basically, it matches
1199 the ATA ID string printed on console by libata. If
1200 the whole ID part is omitted, the last PORT and DEVICE
1201 values are used. If ID hasn't been specified yet, the
1202 configuration applies to all ports, links and devices.
1203
1204 If only DEVICE is omitted, the parameter applies to
1205 the port and all links and devices behind it. DEVICE
1206 number of 0 either selects the first device or the
1207 first fan-out link behind PMP device. It does not
1208 select the host link. DEVICE number of 15 selects the
1209 host link and device attached to it.
1210
1211 The VAL specifies the configuration to force. As long
1212 as there's no ambiguity shortcut notation is allowed.
1213 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1214 The following configurations can be forced.
1215
1216 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1217 Any ID with matching PORT is used.
1218
1219 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1220
1221 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1222 udma[/][16,25,33,44,66,100,133] notation is also
1223 allowed.
1224
1225 * [no]ncq: Turn on or off NCQ.
1226
05944bdf
TH
1227 * nohrst, nosrst, norst: suppress hard, soft
1228 and both resets.
1229
33267325
TH
1230 If there are multiple matching configurations changing
1231 the same attribute, the last one is used.
1232
7c4be253
RD
1233 lmb=debug [KNL] Enable lmb debug messages.
1234
1da177e4 1235 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1236 See Documentation/blockdev/ramdisk.txt.
1da177e4 1237
a6b25b67
RD
1238 lockd.nlm_grace_period=P [NFS] Assign grace period.
1239 Format: <integer>
1da177e4 1240
a6b25b67
RD
1241 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1242 Format: <integer>
1243
1244 lockd.nlm_timeout=T [NFS] Assign timeout value.
1245 Format: <integer>
1246
1247 lockd.nlm_udpport=M [NFS] Assign UDP port.
1248 Format: <integer>
1da177e4
LT
1249
1250 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1251 Format: <irq>
1252
1253 loglevel= All Kernel Messages with a loglevel smaller than the
1254 console loglevel will be printed to the console. It can
1255 also be changed with klogd or other programs. The
1256 loglevels are defined as follows:
1257
1258 0 (KERN_EMERG) system is unusable
1259 1 (KERN_ALERT) action must be taken immediately
1260 2 (KERN_CRIT) critical conditions
1261 3 (KERN_ERR) error conditions
1262 4 (KERN_WARNING) warning conditions
1263 5 (KERN_NOTICE) normal but significant condition
1264 6 (KERN_INFO) informational
1265 7 (KERN_DEBUG) debug-level messages
1266
1267 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1268 Format: { n | nk | nM }
1269 n must be a power of two. The default size
1270 is set in the kernel config file.
1da177e4 1271
accaa24c
RD
1272 logo.nologo [FB] Disables display of the built-in Linux logo.
1273 This may be used to provide more screen space for
1274 kernel log messages and is useful when debugging
1275 kernel boot problems.
1276
1da177e4
LT
1277 lp=0 [LP] Specify parallel ports to use, e.g,
1278 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1279 lp=reset first parallel port). 'lp=0' disables the
1280 lp=auto printer driver. 'lp=reset' (which can be
1281 specified in addition to the ports) causes
1282 attached printers to be reset. Using
1283 lp=port1,port2,... specifies the parallel ports
1284 to associate lp devices with, starting with
1285 lp0. A port specification may be 'none' to skip
1286 that lp device, or a parport name such as
1287 'parport0'. Specifying 'lp=auto' instead of a
1288 port specification list means that device IDs
1289 from each port should be examined, to see if
1290 an IEEE 1284-compliant printer is attached; if
1291 so, the driver will manage that printer.
1292 See also header of drivers/char/lp.c.
1293
1294 lpj=n [KNL]
1295 Sets loops_per_jiffy to given constant, thus avoiding
1296 time-consuming boot-time autodetection (up to 250 ms per
1297 CPU). 0 enables autodetection (default). To determine
1298 the correct value for your kernel, boot with normal
1299 autodetection and see what value is printed. Note that
1300 on SMP systems the preset will be applied to all CPUs,
1301 which is likely to cause problems if your CPUs need
1302 significantly divergent settings. An incorrect value
1303 will cause delays in the kernel to be wrong, leading to
1304 unpredictable I/O errors and other breakage. Although
1305 unlikely, in the extreme case this might damage your
1306 hardware.
1307
1308 ltpc= [NET]
1309 Format: <io>,<irq>,<dma>
1310
a9913044
RD
1311 mac5380= [HW,SCSI] Format:
1312 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1313
a9913044
RD
1314 machvec= [IA64] Force the use of a particular machine-vector
1315 (machvec) in a generic kernel.
1316 Example: machvec=hpzx1_swiotlb
1da177e4 1317
3209e70e
WZ
1318 machtype= [Loongson] Share the same kernel image file between different
1319 yeeloong laptop.
1320 Example: machtype=lemote-yeeloong-2f-7inch
1321
0cb55ad2
RD
1322 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1323 than or equal to this physical address is ignored.
1da177e4
LT
1324
1325 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1326 should make use of. maxcpus=n : n >= 0 limits the
1327 kernel to using 'n' processors. n=0 is a special case,
1328 it is equivalent to "nosmp", which also disables
1329 the IO APIC.
1da177e4 1330
0cb55ad2
RD
1331 max_loop= [LOOP] Maximum number of loopback devices that can
1332 be mounted
1333 Format: <1-256>
2b2c3750 1334
a9913044 1335 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1336 Should be between 1 and 2^32-1.
1337
1338 max_report_luns=
a9913044 1339 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1340 Should be between 1 and 16384.
1341
1da177e4
LT
1342 mcatest= [IA-64]
1343
cd4f0ef7 1344 mce [X86-32] Machine Check Exception
1da177e4 1345
71cced6e 1346 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1347
1da177e4
LT
1348 md= [HW] RAID subsystems devices and level
1349 See Documentation/md.txt.
a9913044 1350
1da177e4
LT
1351 mdacon= [MDA]
1352 Format: <first>,<last>
1353 Specifies range of consoles to be captured by the MDA.
a9913044 1354
1da177e4
LT
1355 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1356 Amount of memory to be used when the kernel is not able
1357 to see the whole system memory or for test.
cd4f0ef7 1358 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1359 address space collisions. Without memmap= PCI devices
1360 could be placed at addresses belonging to unused RAM.
1361
cd4f0ef7 1362 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1363 memory.
1364
6902aa84
PM
1365 memchunk=nn[KMG]
1366 [KNL,SH] Allow user to override the default size for
1367 per-device physically contiguous DMA buffers.
1368
6cececfc 1369 memmap=exactmap [KNL,X86] Enable setting of an exact
1da177e4
LT
1370 E820 memory map, as specified by the user.
1371 Such memmap=exactmap lines can be constructed based on
1372 BIOS output or other requirements. See the memmap=nn@ss
1373 option description.
1374
1375 memmap=nn[KMG]@ss[KMG]
1376 [KNL] Force usage of a specific region of memory
1377 Region of memory to be used, from ss to ss+nn.
1378
1379 memmap=nn[KMG]#ss[KMG]
1380 [KNL,ACPI] Mark specific memory as ACPI data.
1381 Region of memory to be used, from ss to ss+nn.
1382
1383 memmap=nn[KMG]$ss[KMG]
1384 [KNL,ACPI] Mark specific memory as reserved.
1385 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1386 Example: Exclude memory from 0x18690000-0x1869ffff
1387 memmap=64K$0x18690000
1388 or
1389 memmap=0x10000$0x18690000
1da177e4 1390
9f077871
JF
1391 memory_corruption_check=0/1 [X86]
1392 Some BIOSes seem to corrupt the first 64k of
1393 memory when doing things like suspend/resume.
1394 Setting this option will scan the memory
1395 looking for corruption. Enabling this will
1396 both detect corruption and prevent the kernel
1397 from using the memory being corrupted.
1398 However, its intended as a diagnostic tool; if
1399 repeatable BIOS-originated corruption always
1400 affects the same memory, you can use memmap=
1401 to prevent the kernel from using that memory.
1402
1403 memory_corruption_check_size=size [X86]
1404 By default it checks for corruption in the low
1405 64k, making this memory unavailable for normal
1406 use. Use this parameter to scan for
1407 corruption in more or less memory.
1408
1409 memory_corruption_check_period=seconds [X86]
1410 By default it checks for corruption every 60
1411 seconds. Use this parameter to check at some
1412 other rate. 0 disables periodic checking.
1413
caadbdce 1414 memtest= [KNL,X86] Enable memtest
c64df707 1415 Format: <integer>
c64df707 1416 default : 0 <disable>
9e5f6cf5
AH
1417 Specifies the number of memtest passes to be
1418 performed. Each pass selects another test
1419 pattern from a given set of patterns. Memtest
1420 fills the memory with this pattern, validates
1421 memory contents and reserves bad memory
1422 regions that are detected.
c64df707 1423
1da177e4
LT
1424 meye.*= [HW] Set MotionEye Camera parameters
1425 See Documentation/video4linux/meye.txt.
1426
8f36881b
AS
1427 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1428 Multi-Function General Purpose Timers on AMD Geode
1429 platforms.
1430
e6c4dc6c
WT
1431 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1432 the BIOS has incorrectly applied a workaround. TinyBIOS
1433 version 0.98 is known to be affected, 0.99 fixes the
1434 problem by letting the user disable the workaround.
1435
1da177e4
LT
1436 mga= [HW,DRM]
1437
1c207f95
RD
1438 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1439 physical address is ignored.
1440
39f45d7b
MP
1441 mini2440= [ARM,HW,KNL]
1442 Format:[0..2][b][c][t]
1443 Default: "0tb"
1444 MINI2440 configuration specification:
1445 0 - The attached screen is the 3.5" TFT
1446 1 - The attached screen is the 7" TFT
1447 2 - The VGA Shield is attached (1024x768)
1448 Leaving out the screen size parameter will not load
1449 the TFT driver, and the framebuffer will be left
1450 unconfigured.
1451 b - Enable backlight. The TFT backlight pin will be
1452 linked to the kernel VESA blanking code and a GPIO
1453 LED. This parameter is not necessary when using the
1454 VGA shield.
1455 c - Enable the s3c camera interface.
1456 t - Reserved for enabling touchscreen support. The
1457 touchscreen support is not enabled in the mainstream
1458 kernel as of 2.6.30, a preliminary port can be found
1459 in the "bleeding edge" mini2440 support kernel at
1460 http://repo.or.cz/w/linux-2.6/mini2440.git
1461
6b74ab97
MG
1462 mminit_loglevel=
1463 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1464 parameter allows control of the logging verbosity for
1465 the additional memory initialisation checks. A value
1466 of 0 disables mminit logging and a level of 4 will
1467 log everything. Information is printed at KERN_DEBUG
1468 so loglevel=8 may also need to be specified.
1469
1da177e4
LT
1470 mousedev.tap_time=
1471 [MOUSE] Maximum time between finger touching and
1472 leaving touchpad surface for touch to be considered
1473 a tap and be reported as a left button click (for
1474 touchpads working in absolute mode only).
1475 Format: <msecs>
1476 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1477 reporting absolute coordinates, such as tablets
1478 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1479 reporting absolute coordinates, such as tablets
1480
6cececfc 1481 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
0cb55ad2
RD
1482 is similar to kernelcore except it specifies the
1483 amount of memory used for migratable allocations.
1484 If both kernelcore and movablecore is specified,
1485 then kernelcore will be at *least* the specified
1486 value but may be more. If movablecore on its own
1487 is specified, the administrator must be careful
1488 that the amount of memory usable for all allocations
1489 is not too small.
1490
1da177e4
LT
1491 mpu401= [HW,OSS]
1492 Format: <io>,<irq>
1493
1494 MTD_Partition= [MTD]
1495 Format: <name>,<region-number>,<size>,<offset>
1496
a9913044
RD
1497 MTD_Region= [MTD] Format:
1498 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1499
1500 mtdparts= [MTD]
c8facbb6 1501 See drivers/mtd/cmdlinepart.c.
1da177e4 1502
5988af23
RH
1503 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1504
1505 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1506
1507 boundary - index of last SLC block on Flex-OneNAND.
1508 The remaining blocks are configured as MLC blocks.
1509 lock - Configure if Flex-OneNAND boundary should be locked.
1510 Once locked, the boundary cannot be changed.
1511 1 indicates lock status, 0 indicates unlock status.
1512
9db829f4
BD
1513 mtdset= [ARM]
1514 ARM/S3C2412 JIVE boot control
1515
1516 See arch/arm/mach-s3c2412/mach-jive.c
1517
1da177e4 1518 mtouchusb.raw_coordinates=
a9913044
RD
1519 [HW] Make the MicroTouch USB driver use raw coordinates
1520 ('y', default) or cooked coordinates ('n')
1da177e4 1521
0cb55ad2 1522 mtrr_chunk_size=nn[KMG] [X86]
19f59460 1523 used for mtrr cleanup. It is largest continuous chunk
0cb55ad2
RD
1524 that could hold holes aka. UC entries.
1525
1526 mtrr_gran_size=nn[KMG] [X86]
1527 Used for mtrr cleanup. It is granularity of mtrr block.
1528 Default is 1.
1529 Large value could prevent small alignment from
1530 using up MTRRs.
1531
1532 mtrr_spare_reg_nr=n [X86]
1533 Format: <integer>
1534 Range: 0,7 : spare reg number
1535 Default : 1
1536 Used for mtrr cleanup. It is spare mtrr entries number.
1537 Set to 2 or more if your graphical card needs more.
1538
1da177e4
LT
1539 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1540
1541 NCR_D700= [HW,SCSI]
1542 See header of drivers/scsi/NCR_D700.c.
1543
1544 ncr5380= [HW,SCSI]
1545
1546 ncr53c400= [HW,SCSI]
1547
1548 ncr53c400a= [HW,SCSI]
1549
1550 ncr53c406a= [HW,SCSI]
1551
1552 ncr53c8xx= [HW,SCSI]
1553
1554 netdev= [NET] Network devices parameters
1555 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1556 Note that mem_start is often overloaded to mean
1557 something different and driver-specific.
a9913044
RD
1558 This usage is only documented in each driver source
1559 file if at all.
1560
58401572
KPO
1561 nf_conntrack.acct=
1562 [NETFILTER] Enable connection tracking flow accounting
1563 0 to disable accounting
1564 1 to enable accounting
1565 Default value depends on CONFIG_NF_CT_ACCT that is
1566 going to be removed in 2.6.29.
1567
1da177e4 1568 nfsaddrs= [NFS]
dc7a0816 1569 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1570
1571 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
dc7a0816 1572 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4 1573
a72b4422
TM
1574 nfs.callback_tcpport=
1575 [NFS] set the TCP port on which the NFSv4 callback
1576 channel should listen.
1577
e571cbf1
TM
1578 nfs.cache_getent=
1579 [NFS] sets the pathname to the program which is used
1580 to update the NFS client cache entries.
1581
1582 nfs.cache_getent_timeout=
1583 [NFS] sets the timeout after which an attempt to
1584 update a cache entry is deemed to have failed.
1585
58df095b
TM
1586 nfs.idmap_cache_timeout=
1587 [NFS] set the maximum lifetime for idmapper cache
1588 entries.
1589
f43bf0be
TM
1590 nfs.enable_ino64=
1591 [NFS] enable 64-bit inode numbers.
1592 If zero, the NFS client will fake up a 32-bit inode
1593 number for the readdir() and stat() syscalls instead
1594 of returning the full 64-bit number.
1595 The default is to return 64-bit inode numbers.
1596
1e1030dc 1597 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
e7ba176b
HS
1598 when a NMI is triggered.
1599 Format: [state][,regs][,debounce][,die]
1600
6cececfc 1601 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
5b9a0e14
CG
1602 Format: [panic,][num]
1603 Valid num: 0,1,2
1604 0 - turn nmi_watchdog off
1605 1 - use the IO-APIC timer for the NMI watchdog
1606 2 - use the local APIC for the NMI watchdog using
0cb55ad2
RD
1607 a performance counter. Note: This will use one
1608 performance counter and the local APIC's performance
1609 vector.
1610 When panic is specified, panic when an NMI watchdog
1611 timeout occurs.
1612 This is useful when you use a panic=... timeout and
1613 need the box quickly up again.
5b9a0e14
CG
1614 Instead of 1 and 2 it is possible to use the following
1615 symbolic names: lapic and ioapic
1616 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1da177e4 1617
bff38771
AV
1618 netpoll.carrier_timeout=
1619 [NET] Specifies amount of time (in seconds) that
1620 netpoll should wait for a carrier. By default netpoll
1621 waits 4 seconds.
1622
cd4f0ef7 1623 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1624 emulation library even if a 387 maths coprocessor
1625 is present.
1626
0cb55ad2
RD
1627 no_console_suspend
1628 [HW] Never suspend the console
1629 Disable suspending of consoles during suspend and
1630 hibernate operations. Once disabled, debugging
1631 messages can reach various consoles while the rest
1632 of the system is being put to sleep (ie, while
1633 debugging driver suspend/resume hooks). This may
1634 not work reliably with all consoles, but is known
1635 to work with serial and VGA consoles.
1636
c1aee215
CL
1637 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1638 caches in the slab allocator. Saves per-node memory,
1639 but will impact performance.
3395ee05 1640
a9913044
RD
1641 noalign [KNL,ARM]
1642
1da177e4
LT
1643 noapic [SMP,APIC] Tells the kernel to not make use of any
1644 IOAPICs that may be present in the system.
1645
1da177e4
LT
1646 nobats [PPC] Do not use BATs for mapping kernel lowmem
1647 on "Classic" PPC cores.
1648
1649 nocache [ARM]
a9913044 1650
0cb55ad2
RD
1651 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1652
163ecdff
SN
1653 nodelayacct [KNL] Disable per-task delay accounting
1654
1da177e4
LT
1655 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1656
6902aa84
PM
1657 nodsp [SH] Disable hardware DSP at boot time.
1658
6cececfc 1659 noefi [X86] Disable EFI runtime services support.
8b2cb7a8 1660
1da177e4
LT
1661 noexec [IA-64]
1662
6cececfc 1663 noexec [X86]
f5a1b191 1664 On X86-32 available only on PAE configured kernels.
1da177e4 1665 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1666 noexec=off: disable non-executable mappings
1667
1668 noexec32 [X86-64]
1669 This affects only 32-bit executables.
1670 noexec32=on: enable non-executable mappings (default)
1671 read doesn't imply executable mappings
1672 noexec32=off: disable non-executable mappings
1673 read implies executable mappings
1da177e4 1674
6902aa84
PM
1675 nofpu [SH] Disable hardware FPU at boot time.
1676
cd4f0ef7 1677 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1678 register save and restore. The kernel will only save
1679 legacy floating-point registers on task switch.
1da177e4 1680
0c752a93
SS
1681 noxsave [BUGS=X86] Disables x86 extended register state save
1682 and restore using xsave. The kernel will fallback to
1683 enabling legacy floating-point and sse state.
1684
01a24d2b
PZ
1685 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1686 wfi(ARM) instruction doesn't work correctly and not to
1687 use it. This is also useful when using JTAG debugger.
a9913044 1688
cd4f0ef7 1689 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1690 instruction doesn't work correctly and not to
1691 use it.
1692
1f29fae2
SH
1693 no_file_caps Tells the kernel not to honor file capabilities. The
1694 only way then for a file to be executed with privilege
1695 is to be setuid root or executed by root.
1696
1da177e4
LT
1697 nohalt [IA-64] Tells the kernel not to use the power saving
1698 function PAL_HALT_LIGHT when idle. This increases
1699 power-consumption. On the positive side, it reduces
1700 interrupt wake-up latency, which may improve performance
1701 in certain environments such as networked servers or
1702 real-time systems.
1703
79bf2bb3
TG
1704 nohz= [KNL] Boottime enable/disable dynamic ticks
1705 Valid arguments: on, off
1706 Default: on
1707
eeee7853
PM
1708 noiotrap [SH] Disables trapped I/O port accesses.
1709
cd4f0ef7 1710 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1711 disable unhandled interrupt sources.
1712
6cececfc 1713 no_timer_check [X86,APIC] Disables the code which tests for
8542b200
ZA
1714 broken timer IRQ sources.
1715
1da177e4
LT
1716 noisapnp [ISAPNP] Disables ISA PnP code.
1717
1718 noinitrd [RAM] Tells the kernel not to load any configured
1719 initial RAM disk.
1720
03ea8155
WH
1721 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1722 remapping.
1723
1da177e4
LT
1724 nointroute [IA-64]
1725
0aa366f3
TL
1726 nojitter [IA64] Disables jitter checking for ITC timers.
1727
cd4f0ef7 1728 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1729
cd4f0ef7 1730 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1731
1da177e4
LT
1732 noltlbs [PPC] Do not use large page/tlb entries for kernel
1733 lowmem mapping on PPC40x.
1734
312f1f01
H
1735 nomca [IA-64] Disable machine check abort handling
1736
cd4f0ef7 1737 nomce [X86-32] Machine Check Exception
abe37e5a 1738
83d7384f
AS
1739 nomfgpt [X86-32] Disable Multi-Function General Purpose
1740 Timer usage (for AMD Geode machines).
1741
0cb55ad2
RD
1742 norandmaps Don't use address space randomization. Equivalent to
1743 echo 0 > /proc/sys/kernel/randomize_va_space
1744
cd4f0ef7 1745 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1746
cd4f0ef7 1747 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1748 with UP alternatives
1749
1da177e4
LT
1750 noresidual [PPC] Don't use residual data on PReP machines.
1751
a9913044
RD
1752 noresume [SWSUSP] Disables resume and restores original swap
1753 space.
1754
1da177e4
LT
1755 no-scroll [VGA] Disables scrollback.
1756 This is required for the Braillex ib80-piezo Braille
1757 reader made by F.H. Papenmeier (Germany).
1758
1759 nosbagart [IA-64]
1760
cd4f0ef7 1761 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1762
61ec7567
LB
1763 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1764 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1765
97842216
DJ
1766 nosoftlockup [KNL] Disable the soft-lockup detector.
1767
c077719b 1768 noswapaccount [KNL] Disable accounting of swap in memory resource
21acb9ca 1769 controller. (See Documentation/cgroups/memory.txt)
c077719b 1770
1da177e4
LT
1771 nosync [HW,M68K] Disables sync negotiation for all devices.
1772
cd4f0ef7 1773 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1774
1775 nousb [USB] Disable the USB subsystem
1776
1777 nowb [ARM]
a9913044 1778
2b2fd87a
WH
1779 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1780
a6c75b86
FY
1781 nptcg= [IA64] Override max number of concurrent global TLB
1782 purges which is reported from either PAL_VM_SUMMARY or
1783 SAL PALO.
1784
0cb55ad2
RD
1785 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1786
f0c0b2b8
KH
1787 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1788 one of ['zone', 'node', 'default'] can be specified
1789 This can be set from sysctl after boot.
1790 See Documentation/sysctl/vm.txt for details.
1791
7c4be253
RD
1792 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1793 See Documentation/debugging-via-ohci1394.txt for more
1794 info.
1795
3ef0e1f8
AS
1796 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1797 Rather than timing out after 20 ms if an EC
1798 command is not properly ACKed, override the length
1799 of the timeout. We have interrupts disabled while
1800 waiting for the ACK, so if this is set too high
1801 interrupts *may* be lost!
1802
15ac7afe
TL
1803 omap_mux= [OMAP] Override bootloader pin multiplexing.
1804 Format: <mux_mode0.mode_name=value>...
1805 For example, to override I2C bus2:
1806 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1807
1da177e4
LT
1808 opl3= [HW,OSS]
1809 Format: <io>
1810
1da177e4
LT
1811 oprofile.timer= [HW]
1812 Use timer interrupt instead of performance counters
1813
7e4e0bd5
RR
1814 oprofile.cpu_type= Force an oprofile cpu type
1815 This might be useful if you have an older oprofile
1816 userland or if you want common events.
8d7ff4f2
RR
1817 Format: { arch_perfmon }
1818 arch_perfmon: [X86] Force use of architectural
7e4e0bd5
RR
1819 perfmon on Intel CPUs instead of the
1820 CPU specific event set.
1dcdb5a9 1821
1da177e4
LT
1822 osst= [HW,SCSI] SCSI Tape Driver
1823 Format: <buffer_size>,<write_threshold>
1824 See also Documentation/scsi/st.txt.
1825
1826 panic= [KNL] Kernel behaviour on panic
1827 Format: <timeout>
1828
1829 parkbd.port= [HW] Parallel port number the keyboard adapter is
1830 connected to, default is 0.
1831 Format: <parport#>
1832 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1833 0 for XT, 1 for AT (default is AT).
a9913044
RD
1834 Format: <mode>
1835
1836 parport= [HW,PPT] Specify parallel ports. 0 disables.
1837 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1838 Use 'auto' to force the driver to use any
1839 IRQ/DMA settings detected (the default is to
1840 ignore detected IRQ/DMA settings because of
1841 possible conflicts). You can specify the base
1842 address, IRQ, and DMA settings; IRQ and DMA
1843 should be numbers, or 'auto' (for using detected
1844 settings on that particular port), or 'nofifo'
1845 (to avoid using a FIFO even if it is detected).
1846 Parallel ports are assigned in the order they
1847 are specified on the command line, starting
1848 with parport0.
1849
1850 parport_init_mode= [HW,PPT]
1851 Configure VIA parallel port to operate in
1852 a specific mode. This is necessary on Pegasos
1853 computer where firmware has no options for setting
1854 up parallel port mode and sets it to spp.
1855 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1856 Format: [spp|ps2|epp|ecp|ecpepp]
1857
a9913044
RD
1858 pas2= [HW,OSS] Format:
1859 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1860
1da177e4
LT
1861 pas16= [HW,SCSI]
1862 See header of drivers/scsi/pas16.c.
1863
dd287796
AM
1864 pause_on_oops=
1865 Halt all CPUs after the first oops has been printed for
1866 the specified number of seconds. This is to be used if
1867 your oopses keep scrolling off the screen.
1868
1da177e4
LT
1869 pcbit= [HW,ISDN]
1870
1871 pcd. [PARIDE]
1872 See header of drivers/block/paride/pcd.c.
31c00fc1 1873 See also Documentation/blockdev/paride.txt.
1da177e4 1874
a9913044 1875 pci=option[,option...] [PCI] various PCI subsystem options:
1cc0ca26
BH
1876 earlydump [X86] dump PCI config space before the kernel
1877 changes anything
c0115606 1878 off [X86] don't probe for the PCI bus
cd4f0ef7 1879 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1880 the hardware directly. Use this if your machine
1881 has a non-standard PCI host bridge.
cd4f0ef7 1882 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1883 hardware access methods are allowed. Use this
1884 if you experience crashes upon bootup and you
1885 suspect they are caused by the BIOS.
c0115606 1886 conf1 [X86] Force use of PCI Configuration
a9913044 1887 Mechanism 1.
c0115606 1888 conf2 [X86] Force use of PCI Configuration
a9913044 1889 Mechanism 2.
7f785763
RD
1890 noaer [PCIE] If the PCIEAER kernel config parameter is
1891 enabled, this kernel boot option can be used to
1892 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1893 nodomains [PCI] Disable support for multiple PCI
1894 root domains (aka PCI segments, in ACPI-speak).
6cececfc 1895 nommconf [X86] Disable use of MMCONFIG for PCI
61be6d66 1896 Configuration
12983077
AH
1897 check_enable_amd_mmconf [X86] check for and enable
1898 properly configured MMIO access to PCI
1899 config space on AMD family 10h CPU
309e57df
MW
1900 nomsi [MSI] If the PCI_MSI kernel config parameter is
1901 enabled, this kernel boot option can be used to
1902 disable the use of MSI interrupts system-wide.
a9322f64
SA
1903 noioapicquirk [APIC] Disable all boot interrupt quirks.
1904 Safety option to keep boot IRQs enabled. This
1905 should never be necessary.
9197979b
SA
1906 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1907 primary IO-APIC for bridges that cannot disable
1908 boot IRQs. This fixes a source of spurious IRQs
1909 when the system masks IRQs.
41b9eb26
SA
1910 noioapicreroute [APIC] Disable workaround that uses the
1911 boot IRQ equivalent of an IRQ that connects to
1912 a chipset where boot IRQs cannot be disabled.
1913 The opposite of ioapicreroute.
cd4f0ef7 1914 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1915 routing table. These calls are known to be buggy
1916 on several machines and they hang the machine
1917 when used, but on other computers it's the only
1918 way to get the interrupt routing table. Try
1919 this option if the kernel is unable to allocate
1920 IRQs or discover secondary PCI buses on your
1921 motherboard.
c0115606 1922 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1923 Use with caution as certain devices share
1924 address decoders between ROMs and other
1925 resources.
c0115606 1926 norom [X86] Do not assign address space to
bb71ad88
GH
1927 expansion ROMs that do not already have
1928 BIOS assigned address ranges.
c0115606 1929 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1930 assigned automatically to PCI devices. You can
1931 make the kernel exclude IRQs of your ISA cards
1932 this way.
c0115606 1933 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1934 of the PIRQ table (normally generated
1935 by the BIOS) if it is outside the
1936 F0000h-100000h range.
c0115606 1937 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1938 useful if the kernel is unable to find your
1939 secondary buses and you want to tell it
1940 explicitly which ones they are.
c0115606 1941 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1942 numbers ourselves, overriding
1943 whatever the firmware may have done.
c0115606 1944 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1945 in the BIOS $PIR table. This is needed on
1946 some systems with broken BIOSes, notably
1947 some HP Pavilion N5400 and Omnibook XE3
1948 notebooks. This will have no effect if ACPI
1949 IRQ routing is enabled.
c0115606 1950 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1951 or for PCI scanning.
236e946b 1952 use_crs [X86] Use _CRS for PCI resource
62f420f8 1953 allocation.
a9913044
RD
1954 routeirq Do IRQ routing for all PCI devices.
1955 This is normally done in pci_enable_device(),
1956 so this option is a temporary workaround
1957 for broken drivers that don't call it.
13a6ddb0
YL
1958 skip_isa_align [X86] do not align io start addr, so can
1959 handle more pci cards
a9913044
RD
1960 firmware [ARM] Do not re-enumerate the bus but instead
1961 just use the configuration from the
1962 bootloader. This is currently used on
1963 IXP2000 systems where the bus has to be
1964 configured a certain way for adjunct CPUs.
0637a70a
AK
1965 noearly [X86] Don't do any early type 1 scanning.
1966 This might help on some broken boards which
1967 machine check when some devices' config space
1968 is read. But various workarounds are disabled
1969 and some IOMMU drivers will not work.
6b4b78fe
MD
1970 bfsort Sort PCI devices into breadth-first order.
1971 This sorting is done to get a device
1972 order compatible with older (<= 2.4) kernels.
1973 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1974 cbiosize=nn[KMG] The fixed amount of bus space which is
1975 reserved for the CardBus bridge's IO window.
1976 The default value is 256 bytes.
1977 cbmemsize=nn[KMG] The fixed amount of bus space which is
1978 reserved for the CardBus bridge's memory
1979 window. The default value is 64 megabytes.
32a9a682
YS
1980 resource_alignment=
1981 Format:
1982 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1983 Specifies alignment and device to reassign
1984 aligned memory resources.
1985 If <order of align> is not specified,
1986 PAGE_SIZE is used as alignment.
1987 PCI-PCI bridge can be specified, if resource
1988 windows need to be expanded.
43c16408
AP
1989 ecrc= Enable/disable PCIe ECRC (transaction layer
1990 end-to-end CRC checking).
1991 bios: Use BIOS/firmware settings. This is the
1992 the default.
1993 off: Turn ECRC off
1994 on: Turn ECRC on.
6b4b78fe 1995
e5665a45
CE
1996 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1997 Management.
1998 off Disable ASPM.
1999 force Enable ASPM even on devices that claim not to support it.
2000 WARNING: Forcing ASPM on may cause system lockups.
2001
1da177e4
LT
2002 pcmv= [HW,PCMCIA] BadgePAD 4
2003
2004 pd. [PARIDE]
31c00fc1 2005 See Documentation/blockdev/paride.txt.
1da177e4
LT
2006
2007 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2008 boot time.
2009 Format: { 0 | 1 }
2010 See arch/parisc/kernel/pdc_chassis.c
2011
f58dc01b 2012 percpu_alloc= Select which percpu first chunk allocator to use.
e933a73f
TH
2013 Currently supported values are "embed" and "page".
2014 Archs may support subset or none of the selections.
2015 See comments in mm/percpu.c for details on each
2016 allocator. This parameter is primarily for debugging
2017 and performance comparison.
fa8a7094 2018
1da177e4 2019 pf. [PARIDE]
31c00fc1 2020 See Documentation/blockdev/paride.txt.
1da177e4
LT
2021
2022 pg. [PARIDE]
31c00fc1 2023 See Documentation/blockdev/paride.txt.
1da177e4
LT
2024
2025 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 2026 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
2027
2028 plip= [PPT,NET] Parallel port network link
2029 Format: { parport<nr> | timid | 0 }
2030 See also Documentation/parport.txt.
2031
de32a243
TG
2032 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2033 Override pmtimer IOPort with a hex value.
2034 e.g. pmtmr=0x508
2035
97ef062b
BH
2036 pnp.debug [PNP]
2037 Enable PNP debug messages. This depends on the
2038 CONFIG_PNP_DEBUG_MESSAGES option.
2039
1da177e4
LT
2040 pnpacpi= [ACPI]
2041 { off }
2042
2043 pnpbios= [ISAPNP]
2044 { on | off | curr | res | no-curr | no-res }
2045
2046 pnp_reserve_irq=
2047 [ISAPNP] Exclude IRQs for the autoconfiguration
2048
2049 pnp_reserve_dma=
2050 [ISAPNP] Exclude DMAs for the autoconfiguration
2051
2052 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 2053 Ranges are in pairs (I/O port base and size).
1da177e4
LT
2054
2055 pnp_reserve_mem=
a9913044
RD
2056 [ISAPNP] Exclude memory regions for the
2057 autoconfiguration.
1da177e4
LT
2058 Ranges are in pairs (memory base and size).
2059
4af94f39
RD
2060 ports= [IP_VS_FTP] IPVS ftp helper module
2061 Default is 21.
2062 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2063 may be specified.
2064 Format: <port>,<port>....
2065
45807a1d
IM
2066 print-fatal-signals=
2067 [KNL] debug: print fatal signals
f84d49b2
NO
2068
2069 If enabled, warn about various signal handling
2070 related application anomalies: too many signals,
2071 too many POSIX.1 timers, fatal signals causing a
2072 coredump - etc.
2073
2074 If you hit the warning due to signal overflow,
2075 you might want to try "ulimit -i unlimited".
2076
45807a1d
IM
2077 default: off.
2078
e84845c4
RD
2079 printk.time= Show timing data prefixed to each printk message line
2080 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2081
0cb55ad2
RD
2082 processor.max_cstate= [HW,ACPI]
2083 Limit processor to maximum C-state
2084 max_cstate=9 overrides any DMI blacklist limit.
2085
2086 processor.nocst [HW,ACPI]
2087 Ignore the _CST method to determine C-states,
2088 instead using the legacy FADT method
2089
1da177e4 2090 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
2091 Format: [schedule,]<number>
2092 Param: "schedule" - profile schedule points.
2093 Param: <number> - step/bucket size as a power of 2 for
2094 statistical time based profiling.
b3da2a73
MG
2095 Param: "sleep" - profile D-state sleeping (millisecs).
2096 Requires CONFIG_SCHEDSTATS
c0fe2e69 2097 Param: "kvm" - profile VM exits.
1da177e4 2098
1da177e4
LT
2099 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2100 before loading.
31c00fc1 2101 See Documentation/blockdev/ramdisk.txt.
1da177e4 2102
a9913044
RD
2103 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2104 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
2105 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2106 per second.
a9913044
RD
2107 psmouse.resetafter= [HW,MOUSE]
2108 Try to reset the device after so many bad packets
1da177e4
LT
2109 (0 = never).
2110 psmouse.resolution=
2111 [HW,MOUSE] Set desired mouse resolution, in dpi.
2112 psmouse.smartscroll=
a9913044 2113 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
2114 0 = disabled, 1 = enabled (default).
2115
2116 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
2117 Format:
2118 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
2119
2120 pt. [PARIDE]
31c00fc1 2121 See Documentation/blockdev/paride.txt.
1da177e4 2122
dc8c8587
KS
2123 pty.legacy_count=
2124 [KNL] Number of legacy pty's. Overwrites compiled-in
2125 default number.
2126
7d2c502f 2127 quiet [KNL] Disable most log messages
a9913044 2128
1da177e4
LT
2129 r128= [HW,DRM]
2130
2131 raid= [HW,RAID]
2132 See Documentation/md.txt.
2133
a9913044 2134 ramdisk_blocksize= [RAM]
31c00fc1 2135 See Documentation/blockdev/ramdisk.txt.
a9913044 2136
1da177e4 2137 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 2138 See Documentation/blockdev/ramdisk.txt.
1da177e4 2139
24aaef8d
RD
2140 rcupdate.blimit= [KNL,BOOT]
2141 Set maximum number of finished RCU callbacks to process
2142 in one batch.
21a1ea9e 2143
24aaef8d
RD
2144 rcupdate.qhimark= [KNL,BOOT]
2145 Set threshold of queued
21a1ea9e
DS
2146 RCU callbacks over which batch limiting is disabled.
2147
24aaef8d
RD
2148 rcupdate.qlowmark= [KNL,BOOT]
2149 Set threshold of queued RCU callbacks below which
2150 batch limiting is re-enabled.
21a1ea9e 2151
ffdfc409
OJ
2152 rdinit= [KNL]
2153 Format: <full_path>
2154 Run specified binary instead of /init from the ramdisk,
2155 used for early userspace startup. See initrd.
2156
cd4f0ef7 2157 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 2158 Format: <reboot_mode>[,<reboot_mode2>[,...]]
ecb08d81 2159 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 2160
46b6d94e
PJ
2161 relax_domain_level=
2162 [KNL, SMP] Set scheduler's default relax_domain_level.
21acb9ca 2163 See Documentation/cgroups/cpusets.txt.
46b6d94e 2164
1da177e4
LT
2165 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2166
cd4f0ef7 2167 reservetop= [X86-32]
461a9aff
ZA
2168 Format: nn[KMG]
2169 Reserves a hole at the top of the kernel virtual
2170 address space.
2171
7e96287d
VG
2172 reset_devices [KNL] Force drivers to reset the underlying device
2173 during initialization.
2174
a9913044
RD
2175 resume= [SWSUSP]
2176 Specify the partition device for software suspend
1da177e4 2177
ecbd0da1
RW
2178 resume_offset= [SWSUSP]
2179 Specify the offset from the beginning of the partition
2180 given by "resume=" at which the swap header is located,
2181 in <PAGE_SIZE> units (needed only for swap files).
2182 See Documentation/power/swsusp-and-swap-files.txt
2183
0a7b35cb
MN
2184 retain_initrd [RAM] Keep initrd memory after extraction
2185
1da177e4
LT
2186 rhash_entries= [KNL,NET]
2187 Set number of hash buckets for route cache
2188
2189 riscom8= [HW,SERIAL]
2190 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2191
2192 ro [KNL] Mount root device read-only on boot
2193
2194 root= [KNL] Root filesystem
2195
2196 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2197 mount the root filesystem
2198
2199 rootflags= [KNL] Set root filesystem mount option string
2200
2201 rootfstype= [KNL] Set root filesystem type
2202
cc1ed754
PO
2203 rootwait [KNL] Wait (indefinitely) for root device to show up.
2204 Useful for devices that are detected asynchronously
2205 (e.g. USB and MMC devices).
2206
1da177e4
LT
2207 rw [KNL] Mount root device read-write on boot
2208
2209 S [KNL] Run init in single mode
2210
2211 sa1100ir [NET]
2212 See drivers/net/irda/sa1100_ir.c.
2213
1da177e4 2214 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 2215
f6630114
MT
2216 sched_debug [KNL] Enables verbose scheduler debug messages.
2217
1da177e4
LT
2218 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2219 Format: <io>[,<timeout>[,<isapnp>]]
2220
2221 scsi_debug_*= [SCSI]
2222 See drivers/scsi/scsi_debug.c.
2223
2224 scsi_default_dev_flags=
2225 [SCSI] SCSI default device flags
2226 Format: <integer>
2227
2228 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2229 Format: <vendor>:<model>:<flags>
2230 (flags are integer value)
2231
6af6632a
RD
2232 scsi_logging_level= [SCSI] a bit mask of logging levels
2233 See drivers/scsi/scsi_logging.h for bits. Also
2234 settable via sysctl at dev.scsi.logging_level
2235 (/proc/sys/dev/scsi/logging_level).
2236 There is also a nice 'scsi_logging_level' script in the
2237 S390-tools package, available for download at
2238 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 2239
3e082a91
MW
2240 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2241 discovered. async scans them in kernel threads,
2242 allowing boot to proceed. none ignores them, expecting
2243 user space to do the scan.
2244
0cb55ad2
RD
2245 security= [SECURITY] Choose a security module to enable at boot.
2246 If this boot parameter is not specified, only the first
2247 security module asking for security registration will be
2248 loaded. An invalid security module name will be treated
2249 as if no module has been chosen.
2250
2251 selinux= [SELINUX] Disable or enable SELinux at boot time.
1da177e4
LT
2252 Format: { "0" | "1" }
2253 See security/selinux/Kconfig help text.
2254 0 -- disable.
2255 1 -- enable.
2256 Default value is set via kernel config option.
2257 If enabled at boot time, /selinux/disable can be used
2258 later to disable prior to initial policy load.
2259
cd4f0ef7 2260 serialnumber [BUGS=X86-32]
1da177e4 2261
1da177e4
LT
2262 shapers= [NET]
2263 Maximal number of shapers.
a9913044 2264
b05f78f5
YL
2265 show_msr= [x86] show boot-time MSR settings
2266 Format: { <integer> }
2267 Show boot-time (BIOS-initialized) MSR settings.
2268 The parameter means the number of CPUs to show,
2269 for example 1 means boot CPU only.
2270
1da177e4
LT
2271 sim710= [SCSI,HW]
2272 See header of drivers/scsi/sim710.c.
2273
2274 simeth= [IA-64]
2275 simscsi=
a9913044 2276
1da177e4
LT
2277 slram= [HW,MTD]
2278
f0630fff
CL
2279 slub_debug[=options[,slabs]] [MM, SLUB]
2280 Enabling slub_debug allows one to determine the
2281 culprit if slab objects become corrupted. Enabling
2282 slub_debug can create guard zones around objects and
2283 may poison objects when not in use. Also tracks the
2284 last alloc / free. For more information see
2285 Documentation/vm/slub.txt.
c1aee215
CL
2286
2287 slub_max_order= [MM, SLUB]
f0630fff
CL
2288 Determines the maximum allowed order for slabs.
2289 A high setting may cause OOMs due to memory
2290 fragmentation. For more information see
2291 Documentation/vm/slub.txt.
c1aee215
CL
2292
2293 slub_min_objects= [MM, SLUB]
f0630fff
CL
2294 The minimum number of objects per slab. SLUB will
2295 increase the slab order up to slub_max_order to
2296 generate a sufficiently large slab able to contain
2297 the number of objects indicated. The higher the number
2298 of objects the smaller the overhead of tracking slabs
2299 and the less frequently locks need to be acquired.
c1aee215
CL
2300 For more information see Documentation/vm/slub.txt.
2301
2302 slub_min_order= [MM, SLUB]
2303 Determines the mininum page order for slabs. Must be
f0630fff 2304 lower than slub_max_order.
c1aee215
CL
2305 For more information see Documentation/vm/slub.txt.
2306
2307 slub_nomerge [MM, SLUB]
f0630fff 2308 Disable merging of slabs with similar size. May be
c1aee215 2309 necessary if there is some reason to distinguish
f0630fff
CL
2310 allocs to different slabs. Debug options disable
2311 merging on their own.
c1aee215
CL
2312 For more information see Documentation/vm/slub.txt.
2313
1da177e4
LT
2314 smart2= [HW]
2315 Format: <io1>[,<io2>[,...,<io8>]]
2316
cd4f0ef7 2317 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2318 attempt to substitute SMP alternatives once at boot.
2319
d0d4f69b
BH
2320 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2321 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2322 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2323 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2324 smsc-ircc2.ircc_irq= [HW] IRQ line
2325 smsc-ircc2.ircc_dma= [HW] DMA channel
2326 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2327 0: Toshiba Satellite 1800 (GP data pin select)
2328 1: Fast pin select (default)
2329 2: ATC IRMode
2330
1da177e4
LT
2331 snd-ad1816a= [HW,ALSA]
2332
2333 snd-ad1848= [HW,ALSA]
2334
2335 snd-ali5451= [HW,ALSA]
2336
2337 snd-als100= [HW,ALSA]
2338
2339 snd-als4000= [HW,ALSA]
2340
2341 snd-azt2320= [HW,ALSA]
2342
2343 snd-cmi8330= [HW,ALSA]
2344
2345 snd-cmipci= [HW,ALSA]
2346
2347 snd-cs4231= [HW,ALSA]
2348
2349 snd-cs4232= [HW,ALSA]
2350
2351 snd-cs4236= [HW,ALSA]
2352
2353 snd-cs4281= [HW,ALSA]
2354
2355 snd-cs46xx= [HW,ALSA]
2356
2357 snd-dt019x= [HW,ALSA]
2358
2359 snd-dummy= [HW,ALSA]
2360
2361 snd-emu10k1= [HW,ALSA]
2362
2363 snd-ens1370= [HW,ALSA]
2364
2365 snd-ens1371= [HW,ALSA]
2366
2367 snd-es968= [HW,ALSA]
2368
2369 snd-es1688= [HW,ALSA]
2370
2371 snd-es18xx= [HW,ALSA]
2372
2373 snd-es1938= [HW,ALSA]
2374
2375 snd-es1968= [HW,ALSA]
2376
2377 snd-fm801= [HW,ALSA]
2378
2379 snd-gusclassic= [HW,ALSA]
2380
2381 snd-gusextreme= [HW,ALSA]
2382
2383 snd-gusmax= [HW,ALSA]
2384
2385 snd-hdsp= [HW,ALSA]
2386
2387 snd-ice1712= [HW,ALSA]
2388
2389 snd-intel8x0= [HW,ALSA]
2390
2391 snd-interwave= [HW,ALSA]
2392
2393 snd-interwave-stb=
2394 [HW,ALSA]
2395
2396 snd-korg1212= [HW,ALSA]
2397
2398 snd-maestro3= [HW,ALSA]
2399
2400 snd-mpu401= [HW,ALSA]
2401
2402 snd-mtpav= [HW,ALSA]
2403
2404 snd-nm256= [HW,ALSA]
2405
2406 snd-opl3sa2= [HW,ALSA]
2407
2408 snd-opti92x-ad1848=
2409 [HW,ALSA]
2410
2411 snd-opti92x-cs4231=
2412 [HW,ALSA]
2413
2414 snd-opti93x= [HW,ALSA]
2415
2416 snd-pmac= [HW,ALSA]
2417
2418 snd-rme32= [HW,ALSA]
2419
2420 snd-rme96= [HW,ALSA]
2421
2422 snd-rme9652= [HW,ALSA]
2423
2424 snd-sb8= [HW,ALSA]
2425
2426 snd-sb16= [HW,ALSA]
2427
2428 snd-sbawe= [HW,ALSA]
2429
2430 snd-serial= [HW,ALSA]
2431
2432 snd-sgalaxy= [HW,ALSA]
2433
2434 snd-sonicvibes= [HW,ALSA]
2435
2436 snd-sun-amd7930=
2437 [HW,ALSA]
2438
2439 snd-sun-cs4231= [HW,ALSA]
2440
2441 snd-trident= [HW,ALSA]
2442
2443 snd-usb-audio= [HW,ALSA,USB]
2444
2445 snd-via82xx= [HW,ALSA]
2446
2447 snd-virmidi= [HW,ALSA]
2448
2449 snd-wavefront= [HW,ALSA]
2450
2451 snd-ymfpci= [HW,ALSA]
a9913044 2452
9c44bc03
IM
2453 softlockup_panic=
2454 [KNL] Should the soft-lockup detector generate panics.
2455
1da177e4
LT
2456 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2457 See Documentation/sonypi.txt
2458
2459 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2460 See Documentation/serial/specialix.txt.
1da177e4
LT
2461
2462 spia_io_base= [HW,MTD]
2463 spia_fio_base=
2464 spia_pedr=
2465 spia_peddr=
2466
2467 sscape= [HW,OSS]
2468 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2469
1da177e4
LT
2470 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2471 See Documentation/scsi/st.txt.
2472
f38f1d2a
SR
2473 stacktrace [FTRACE]
2474 Enabled the stack tracer on boot up.
2475
1da177e4
LT
2476 sti= [PARISC,HW]
2477 Format: <num>
2478 Set the STI (builtin display/keyboard on the HP-PARISC
2479 machines) console (graphic card) which should be used
2480 as the initial boot-console.
2481 See also comment in drivers/video/console/sticore.c.
2482
2483 sti_font= [HW]
2484 See comment in drivers/video/console/sticore.c.
2485
2486 stifb= [HW]
2487 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2488
cbf11071
TM
2489 sunrpc.min_resvport=
2490 sunrpc.max_resvport=
2491 [NFS,SUNRPC]
2492 SunRPC servers often require that client requests
2493 originate from a privileged port (i.e. a port in the
2494 range 0 < portnr < 1024).
2495 An administrator who wishes to reserve some of these
2496 ports for other uses may adjust the range that the
2497 kernel's sunrpc client considers to be privileged
2498 using these two parameters to set the minimum and
2499 maximum port values.
2500
42a7fc4a
GB
2501 sunrpc.pool_mode=
2502 [NFS]
2503 Control how the NFS server code allocates CPUs to
2504 service thread pools. Depending on how many NICs
2505 you have and where their interrupts are bound, this
2506 option will affect which CPUs will do NFS serving.
2507 Note: this parameter cannot be changed while the
2508 NFS server is running.
2509
2510 auto the server chooses an appropriate mode
2511 automatically using heuristics
2512 global a single global pool contains all CPUs
2513 percpu one pool for each CPU
2514 pernode one pool for each NUMA node (equivalent
2515 to global on non-NUMA machines)
2516
cbf11071
TM
2517 sunrpc.tcp_slot_table_entries=
2518 sunrpc.udp_slot_table_entries=
2519 [NFS,SUNRPC]
2520 Sets the upper limit on the number of simultaneous
2521 RPC calls that can be sent from the client to a
2522 server. Increasing these values may allow you to
2523 improve throughput, but will also increase the
2524 amount of memory reserved for use by the client.
2525
1da177e4 2526 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2527
1da177e4
LT
2528 switches= [HW,M68k]
2529
2530 sym53c416= [HW,SCSI]
2531 See header of drivers/scsi/sym53c416.c.
2532
5d6f647f
IM
2533 sysrq_always_enabled
2534 [KNL]
2535 Ignore sysrq setting - this boot parameter will
2536 neutralize any effect of /proc/sys/kernel/sysrq.
2537 Useful for debugging.
2538
1da177e4
LT
2539 t128= [HW,SCSI]
2540 See header of drivers/scsi/t128.c.
2541
2542 tdfx= [HW,DRM]
2543
77437fd4
DB
2544 test_suspend= [SUSPEND]
2545 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2546 standby suspend) as the system sleep state to briefly
2547 enter during system startup. The system is woken from
2548 this state using a wakeup-capable RTC alarm.
2549
1da177e4
LT
2550 thash_entries= [KNL,NET]
2551 Set number of hash buckets for TCP connection
2552
f8707ec9
LB
2553 thermal.act= [HW,ACPI]
2554 -1: disable all active trip points in all thermal zones
2555 <degrees C>: override all lowest active trip points
2556
c52a7419
LB
2557 thermal.crt= [HW,ACPI]
2558 -1: disable all critical trip points in all thermal zones
22a94d79 2559 <degrees C>: override all critical trip points
c52a7419 2560
f5487145
LB
2561 thermal.nocrt= [HW,ACPI]
2562 Set to disable actions on ACPI thermal zone
2563 critical and hot trip points.
2564
72b33ef8
LB
2565 thermal.off= [HW,ACPI]
2566 1: disable ACPI thermal control
2567
a70cdc52
LB
2568 thermal.psv= [HW,ACPI]
2569 -1: disable all passive trip points
ada9cfdd
RD
2570 <degrees C>: override all passive trip points to this
2571 value
a70cdc52 2572
730ff34d
LB
2573 thermal.tzp= [HW,ACPI]
2574 Specify global default ACPI thermal zone polling rate
2575 <deci-seconds>: poll all this frequency
2576 0: no polling (default)
2577
1da177e4
LT
2578 tmscsim= [HW,SCSI]
2579 See comment before function dc390_setup() in
2580 drivers/scsi/tmscsim.c.
2581
2b1a61f0
HC
2582 topology= [S390]
2583 Format: {off | on}
2584 Specify if the kernel should make use of the cpu
2585 topology informations if the hardware supports these.
2586 The scheduler will make use of these informations and
2587 e.g. base its process migration decisions on it.
2588 Default is off.
2589
1da177e4
LT
2590 tp720= [HW,PS2]
2591
9d612bef
LZ
2592 trace_buf_size=nn[KMG]
2593 [FTRACE] will set tracing buffer size.
631595fb 2594
020e5f85
LZ
2595 trace_event=[event-list]
2596 [FTRACE] Set and start specified trace events in order
2597 to facilitate early boot debugging.
2598 See also Documentation/trace/events.txt
2599
1da177e4 2600 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2601 Format:
2602 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2603
395628ef
AK
2604 tsc= Disable clocksource-must-verify flag for TSC.
2605 Format: <string>
2606 [x86] reliable: mark tsc clocksource as reliable, this
2607 disables clocksource verification at runtime.
2608 Used to enable high-resolution timer mode on older
2609 hardware, and in virtualized environment.
2610
a9913044
RD
2611 turbografx.map[2|3]= [HW,JOY]
2612 TurboGraFX parallel port interface
2613 Format:
2614 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2615 See also Documentation/input/joystick-parport.txt
2616
2617 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2618 See header of drivers/scsi/u14-34f.c.
2619
2620 uart401= [HW,OSS]
2621 Format: <io>,<irq>
2622
2623 uart6850= [HW,OSS]
2624 Format: <io>,<irq>
2625
f86dcc5a
ED
2626 uhash_entries= [KNL,NET]
2627 Set number of hash buckets for UDP/UDP-Lite connections
2628
5f8364b7
AS
2629 uhci-hcd.ignore_oc=
2630 [USB] Ignore overcurrent events (default N).
2631 Some badly-designed motherboards generate lots of
2632 bogus events, for ports that aren't wired to
2633 anything. Set this parameter to avoid log spamming.
2634 Note that genuine overcurrent events won't be
2635 reported either.
2636
e3a61b0a 2637 unknown_nmi_panic
6cececfc 2638 [X86]
e3a61b0a
SA
2639 Set unknown_nmi_panic=1 early on boot.
2640
b5e795f8
AS
2641 usbcore.autosuspend=
2642 [USB] The autosuspend time delay (in seconds) used
2643 for newly-detected USB devices (default 2). This
2644 is the time required before an idle device will be
2645 autosuspended. Devices for which the delay is set
eaafbc3a 2646 to a negative value won't be autosuspended at all.
b5e795f8 2647
fd7c519d
JK
2648 usbcore.usbfs_snoop=
2649 [USB] Set to log all usbfs traffic (default 0 = off).
2650
2651 usbcore.blinkenlights=
2652 [USB] Set to cycle leds on hubs (default 0 = off).
2653
2654 usbcore.old_scheme_first=
2655 [USB] Start with the old device initialization
2656 scheme (default 0 = off).
2657
2658 usbcore.use_both_schemes=
2659 [USB] Try the other device initialization scheme
2660 if the first one fails (default 1 = enabled).
2661
2662 usbcore.initial_descriptor_timeout=
2663 [USB] Specifies timeout for the initial 64-byte
2664 USB_REQ_GET_DESCRIPTOR request in milliseconds
2665 (default 5000 = 5.0 seconds).
2666
1da177e4
LT
2667 usbhid.mousepoll=
2668 [USBHID] The interval which mice are to be polled at.
a9913044 2669
d4f373e5
AS
2670 usb-storage.delay_use=
2671 [UMS] The delay in seconds before a new device is
2672 scanned for Logical Units (default 5).
2673
2674 usb-storage.quirks=
2675 [UMS] A list of quirks entries to supplement or
2676 override the built-in unusual_devs list. List
2677 entries are separated by commas. Each entry has
2678 the form VID:PID:Flags where VID and PID are Vendor
2679 and Product ID values (4-digit hex numbers) and
2680 Flags is a set of characters, each corresponding
2681 to a common usb-storage quirk flag as follows:
c838ea46
AS
2682 a = SANE_SENSE (collect more than 18 bytes
2683 of sense data);
a0bb1081
AS
2684 b = BAD_SENSE (don't collect more than 18
2685 bytes of sense data);
d4f373e5
AS
2686 c = FIX_CAPACITY (decrease the reported
2687 device capacity by one sector);
c838ea46
AS
2688 h = CAPACITY_HEURISTICS (decrease the
2689 reported device capacity by one
2690 sector if the number is odd);
d4f373e5
AS
2691 i = IGNORE_DEVICE (don't bind to this
2692 device);
2693 l = NOT_LOCKABLE (don't try to lock and
2694 unlock ejectable media);
2695 m = MAX_SECTORS_64 (don't transfer more
2696 than 64 sectors = 32 KB at a time);
c838ea46
AS
2697 o = CAPACITY_OK (accept the capacity
2698 reported by the device);
d4f373e5
AS
2699 r = IGNORE_RESIDUE (the device reports
2700 bogus residue values);
2701 s = SINGLE_LUN (the device has only one
2702 Logical Unit);
2703 w = NO_WP_DETECT (don't test whether the
2704 medium is write-protected).
2705 Example: quirks=0419:aaf5:rl,0421:0433:rc
2706
6cececfc 2707 vdso= [X86,SH]
1dbf527c 2708 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2709 vdso=1: enable VDSO (default)
2710 vdso=0: disable VDSO mapping
2711
6cececfc 2712 vdso32= [X86]
af65d648
RM
2713 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2714 vdso32=1: enable 32-bit VDSO (default)
2715 vdso32=0: disable 32-bit VDSO mapping
2716
d080d397
YI
2717 vector= [IA-64,SMP]
2718 vector=percpu: enable percpu vector domain
2719
1da177e4
LT
2720 video= [FB] Frame buffer configuration
2721 See Documentation/fb/modedb.txt.
2722
cd4f0ef7 2723 vga= [BOOT,X86-32] Select a particular video mode
954a8b81 2724 See Documentation/x86/boot.txt and
a9913044 2725 Documentation/svga.txt.
1da177e4
LT
2726 Use vga=ask for menu.
2727 This is actually a boot loader parameter; the value is
2728 passed to the kernel using a special protocol.
2729
a9913044 2730 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2731 size of <nn>. This can be used to increase the
2732 minimum size (128MB on x86). It can also be used to
2733 decrease the size and leave more room for directly
2734 mapped kernel RAM.
2735
585c3047
PO
2736 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2737 Format: <command>
1da177e4 2738
585c3047
PO
2739 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2740 Format: <command>
2741
2742 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2743 Format: <command>
a9913044 2744
9ea9a886
CL
2745 vt.cur_default= [VT] Default cursor shape.
2746 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2747 the parameters of the <Esc>[?A;B;Cc escape sequence;
2748 see VGA-softcursor.txt. Default: 2 = underline.
2749
0cb55ad2
RD
2750 vt.default_blu= [VT]
2751 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2752 Change the default blue palette of the console.
2753 This is a 16-member array composed of values
2754 ranging from 0-255.
2755
2756 vt.default_grn= [VT]
2757 Format: <green0>,<green1>,<green2>,...,<green15>
2758 Change the default green palette of the console.
2759 This is a 16-member array composed of values
2760 ranging from 0-255.
2761
2762 vt.default_red= [VT]
2763 Format: <red0>,<red1>,<red2>,...,<red15>
2764 Change the default red palette of the console.
2765 This is a 16-member array composed of values
2766 ranging from 0-255.
2767
2768 vt.default_utf8=
2769 [VT]
2770 Format=<0|1>
2771 Set system-wide default UTF-8 mode for all tty's.
2772 Default is 1, i.e. UTF-8 mode is enabled for all
2773 newly opened terminals.
2774
f6c06b68
MG
2775 vt.global_cursor_default=
2776 [VT]
2777 Format=<-1|0|1>
2778 Set system-wide default for whether a cursor
2779 is shown on new VTs. Default is -1,
2780 i.e. cursors will be created by default unless
2781 overridden by individual drivers. 0 will hide
2782 cursors, 1 will display them.
2783
1da177e4
LT
2784 waveartist= [HW,OSS]
2785 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2786
1da177e4
LT
2787 wd33c93= [HW,SCSI]
2788 See header of drivers/scsi/wd33c93.c.
2789
2790 wd7000= [HW,SCSI]
2791 See header of drivers/scsi/wd7000.c.
2792
2793 wdt= [WDT] Watchdog
8dfe9c21 2794 See Documentation/watchdog/wdt.txt.
1da177e4 2795
0cb55ad2
RD
2796 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2797 default x2apic cluster mode on platforms
2798 supporting x2apic.
2799
1da177e4
LT
2800 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2801 xd_geo= See header of drivers/block/xd.c.
2802
2803 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2804 Format:
2805 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2806
a9913044 2807______________________________________________________________________
1da177e4
LT
2808
2809TODO:
2810
2811 Add documentation for ALSA options.
2812 Add more DRM drivers.