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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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20This document may not be entirely up to date and comprehensive. The command
21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22module. Loadable modules, after being loaded into the running kernel, also
23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24parameters may be changed at runtime by the command
25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
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27The parameters listed below are only valid if certain kernel build options were
28enabled and if respective hardware is present. The text in square brackets at
29the beginning of each description states the restrictions within which a
30parameter is applicable:
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31
32 ACPI ACPI support is enabled.
c99c108a 33 AGP AGP (Accelerated Graphics Port) is enabled.
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34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
e7ba176b 37 AVR32 AVR32 architecture is enabled.
1da177e4 38 AX25 Appropriate AX.25 support is enabled.
0ae53640 39 BLACKFIN Blackfin architecture is enabled.
a9913044 40 DRM Direct Rendering Management support is enabled.
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41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
1da177e4 46 IA-64 IA-64 architecture is enabled.
6146f0d5 47 IMA Integrity measurement architecture is enabled.
1da177e4 48 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 49 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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50 ISAPNP ISA PnP code is enabled.
51 ISDN Appropriate ISDN support is enabled.
52 JOY Appropriate joystick support is enabled.
b9ce08c0 53 KMEMTRACE kmemtrace is enabled.
11ef697b 54 LIBATA Libata driver is enabled
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55 LP Printer support is enabled.
56 LOOP Loopback device support is enabled.
57 M68k M68k architecture is enabled.
58 These options have more detailed description inside of
59 Documentation/m68k/kernel-options.txt.
60 MCA MCA bus support is enabled.
61 MDA MDA console support is enabled.
62 MOUSE Appropriate mouse support is enabled.
309e57df 63 MSI Message Signaled Interrupts (PCI).
c8facbb6 64 MTD MTD (Memory Technology Device) support is enabled.
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65 NET Appropriate network support is enabled.
66 NUMA NUMA support is enabled.
734efb46 67 GENERIC_TIME The generic timeofday code is enabled.
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68 NFS Appropriate NFS support is enabled.
69 OSS OSS sound support is enabled.
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70 PV_OPS A paravirtualized kernel is enabled.
71 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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72 PARISC The PA-RISC architecture is enabled.
73 PCI PCI bus support is enabled.
7f785763 74 PCIE PCI Express support is enabled.
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75 PCMCIA The PCMCIA subsystem is enabled.
76 PNP Plug & Play support is enabled.
77 PPC PowerPC architecture is enabled.
78 PPT Parallel port support is enabled.
79 PS2 Appropriate PS/2 support is enabled.
80 RAM RAM disk support is enabled.
20510f2f 81 ROOTPLUG The example Root Plug LSM is enabled.
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82 S390 S390 architecture is enabled.
83 SCSI Appropriate SCSI support is enabled.
84 A lot of drivers has their options described inside of
85 Documentation/scsi/.
20510f2f 86 SECURITY Different security models are enabled.
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87 SELINUX SELinux support is enabled.
88 SERIAL Serial support is enabled.
e523d93c 89 SH SuperH architecture is enabled.
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90 SMP The kernel is an SMP kernel.
91 SPARC Sparc architecture is enabled.
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92 SWSUSP Software suspend (hibernation) is enabled.
93 SUSPEND System suspend states are enabled.
f38f1d2a 94 FTRACE Function tracing enabled.
1da177e4 95 TS Appropriate touchscreen support is enabled.
d4f373e5 96 UMS USB Mass Storage support is enabled.
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97 USB USB support is enabled.
98 USBHID USB Human Interface Device support is enabled.
99 V4L Video For Linux support is enabled.
100 VGA The VGA console has been enabled.
101 VT Virtual terminal support is enabled.
102 WDT Watchdog support is enabled.
103 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 104 X86-32 X86-32, aka i386 architecture is enabled.
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105 X86-64 X86-64 architecture is enabled.
106 More X86-64 boot options can be found in
71cced6e 107 Documentation/x86/x86_64/boot-options.txt .
c0115606 108 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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109
110In addition, the following text indicates that the option:
111
112 BUGS= Relates to possible processor bugs on the said processor.
113 KNL Is a kernel start-up parameter.
114 BOOT Is a boot loader parameter.
115
116Parameters denoted with BOOT are actually interpreted by the boot
117loader, and have no meaning to the kernel directly.
118Do not modify the syntax of boot loader parameters without extreme
954a8b81 119need or coordination with <Documentation/x86/boot.txt>.
1da177e4 120
5558870b 121There are also arch-specific kernel-parameters not documented here.
71cced6e 122See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 123
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124Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
125a trailing = on the name of any parameter states that that parameter will
126be entered as an environment variable, whereas its absence indicates that
127it will appear as a kernel argument readable via /proc/cmdline by programs
128running once the system is up.
129
9c4751fd 130The number of kernel parameters is not limited, but the length of the
131complete command line (parameters including spaces etc.) is limited to
132a fixed number of characters. This limit depends on the architecture
133and is between 256 and 4096 characters. It is defined in the file
134./include/asm/setup.h as COMMAND_LINE_SIZE.
135
136
6cececfc 137 acpi= [HW,ACPI,X86]
03d926f8 138 Advanced Configuration and Power Interface
af23f573 139 Format: { force | off | ht | strict | noirq | rsdt }
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140 force -- enable ACPI if default was off
141 off -- disable ACPI if default was on
142 noirq -- do not use ACPI for IRQ routing
143 ht -- run only enough ACPI to enable Hyper Threading
a9913044 144 strict -- Be less tolerant of platforms that are not
1da177e4 145 strictly ACPI specification compliant.
237889bf 146 rsdt -- prefer RSDT over (default) XSDT
1da177e4 147
53471121 148 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 149
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150 acpi_apic_instance= [ACPI, IOAPIC]
151 Format: <int>
152 2: use 2nd APIC table, if available
153 1,0: use 1st APIC table
4e381a4f 154 default: 0
a1fdcc0d 155
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156 acpi_backlight= [HW,ACPI]
157 acpi_backlight=vendor
158 acpi_backlight=video
159 If set to vendor, prefer vendor specific driver
160 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
161 of the ACPI video.ko driver.
162
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163 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
164 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 165 Format: <int>
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166 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
167 debug output. Bits in debug_layer correspond to a
168 _COMPONENT in an ACPI source file, e.g.,
169 #define _COMPONENT ACPI_PCI_COMPONENT
170 Bits in debug_level correspond to a level in
171 ACPI_DEBUG_PRINT statements, e.g.,
172 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
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173 The debug_level mask defaults to "info". See
174 Documentation/acpi/debug.txt for more information about
175 debug layers and levels.
a0d84a92 176
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177 Enable processor driver info messages:
178 acpi.debug_layer=0x20000000
179 Enable PCI/PCI interrupt routing info messages:
180 acpi.debug_layer=0x400000
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181 Enable AML "Debug" output, i.e., stores to the Debug
182 object while interpreting AML:
183 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
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184 Enable all messages related to ACPI hardware:
185 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
186
187 Some values produce so much output that the system is
188 unusable. The "log_buf_len" parameter may be useful
189 if you need to capture more output.
f989106c 190
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191 acpi_display_output= [HW,ACPI]
192 acpi_display_output=vendor
193 acpi_display_output=video
194 See above.
195
196 acpi_irq_balance [HW,ACPI]
197 ACPI will balance active IRQs
198 default in APIC mode
199
200 acpi_irq_nobalance [HW,ACPI]
201 ACPI will not move active IRQs (default)
202 default in PIC mode
203
204 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
205 Format: <irq>,<irq>...
206
207 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
208 use by PCI
209 Format: <irq>,<irq>...
210
211 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
212
213 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
214 Format: To spoof as Windows 98: ="Microsoft Windows"
215
216 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
217 acpi_osi="string1" # add string1 -- only one string
218 acpi_osi="!string2" # remove built-in string2
219 acpi_osi= # disable all strings
220
6cececfc 221 acpi_pm_good [X86]
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222 Override the pmtimer bug detection: force the kernel
223 to assume that this machine's pmtimer latches its value
224 and always returns good values.
225
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226 acpi.power_nocheck= [HW,ACPI]
227 Format: 1/0 enable/disable the check of power state.
228 On some bogus BIOS the _PSC object/_STA object of
229 power resource can't return the correct device power
230 state. In such case it is unneccessary to check its
231 power state again in power transition.
232 1 : disable the power state check
233
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234 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
235 Format: { level | edge | high | low }
236
237 acpi_serialize [HW,ACPI] force serialization of AML methods
238
239 acpi_skip_timer_override [HW,ACPI]
240 Recognize and ignore IRQ0/pin2 Interrupt Override.
241 For broken nForce2 BIOS resulting in XT-PIC timer.
242
243 acpi_sleep= [HW,ACPI] Sleep options
244 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
245 old_ordering, s4_nonvs }
246 See Documentation/power/video.txt for information on
247 s3_bios and s3_mode.
248 s3_beep is for debugging; it makes the PC's speaker beep
249 as soon as the kernel's real-mode entry point is called.
250 s4_nohwsig prevents ACPI hardware signature from being
251 used during resume from hibernation.
252 old_ordering causes the ACPI 1.0 ordering of the _PTS
253 control method, with respect to putting devices into
254 low power states, to be enforced (the ACPI 2.0 ordering
255 of _PTS is used by default).
256 s4_nonvs prevents the kernel from saving/restoring the
257 ACPI NVS memory during hibernation.
258
259 acpi_use_timer_override [HW,ACPI]
260 Use timer override. For some broken Nvidia NF5 boards
261 that require a timer override, but don't have HPET
262
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263 acpi_enforce_resources= [ACPI]
264 { strict | lax | no }
265 Check for resource conflicts between native drivers
266 and ACPI OperationRegions (SystemIO and SystemMemory
267 only). IO ports and memory declared in ACPI might be
268 used by the ACPI subsystem in arbitrary AML code and
269 can interfere with legacy drivers.
270 strict (default): access to resources claimed by ACPI
271 is denied; legacy drivers trying to access reserved
272 resources will fail to bind to device using them.
273 lax: access to resources claimed by ACPI is allowed;
274 legacy drivers trying to access reserved resources
275 will bind successfully but a warning message is logged.
276 no: ACPI OperationRegions are not marked as reserved,
277 no further checks are performed.
278
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279 ad1848= [HW,OSS]
280 Format: <io>,<irq>,<dma>,<dma2>,<type>
281
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282 add_efi_memmap [EFI; X86] Include EFI memory map in
283 kernel's map of available physical RAM.
284
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285 advansys= [HW,SCSI]
286 See header of drivers/scsi/advansys.c.
287
288 advwdt= [HW,WDT] Advantech WDT
289 Format: <iostart>,<iostop>
290
291 aedsp16= [HW,OSS] Audio Excel DSP 16
292 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
293 See also header of sound/oss/aedsp16.c.
a9913044 294
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295 agp= [AGP]
296 { off | try_unsupported }
297 off: disable AGP support
298 try_unsupported: try to drive unsupported chipsets
299 (may crash computer or cause data corruption)
300
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301 aha152x= [HW,SCSI]
302 See Documentation/scsi/aha152x.txt.
303
304 aha1542= [HW,SCSI]
305 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
306
307 aic7xxx= [HW,SCSI]
308 See Documentation/scsi/aic7xxx.txt.
309
310 aic79xx= [HW,SCSI]
311 See Documentation/scsi/aic79xx.txt.
312
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313 amd_iommu= [HW,X86-84]
314 Pass parameters to the AMD IOMMU driver in the system.
315 Possible values are:
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316 isolate - enable device isolation (each device, as far
317 as possible, will get its own protection
3ce1f93c 318 domain) [default]
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319 share - put every device behind one IOMMU into the
320 same protection domain
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321 fullflush - enable flushing of IO/TLB entries when
322 they are unmapped. Otherwise they are
323 flushed before they will be reused, which
324 is a lot of faster
325
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326 amd_iommu_size= [HW,X86-64]
327 Define the size of the aperture for the AMD IOMMU
328 driver. Possible values are:
329 '32M', '64M' (default), '128M', '256M', '512M', '1G'
330
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331 amijoy.map= [HW,JOY] Amiga joystick support
332 Map of devices attached to JOY0DAT and JOY1DAT
333 Format: <a>,<b>
334 See also Documentation/kernel/input/joystick.txt
335
336 analog.map= [HW,JOY] Analog joystick and gamepad support
337 Specifies type or capabilities of an analog joystick
338 connected to one of 16 gameports
339 Format: <type1>,<type2>,..<type16>
340
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341 apc= [HW,SPARC]
342 Power management functions (SPARCstation-4/5 + deriv.)
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343 Format: noidle
344 Disable APC CPU standby support. SPARCstation-Fox does
345 not play well with APC CPU idle - disable it if you have
346 APC and your system crashes randomly.
347
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348 apic= [APIC,i386] Advanced Programmable Interrupt Controller
349 Change the output verbosity whilst booting
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350 Format: { quiet (default) | verbose | debug }
351 Change the amount of debugging information output
352 when initialising the APIC and IO-APIC components.
a9913044 353
1da177e4 354 apm= [APM] Advanced Power Management
71f77055 355 See header of arch/x86/kernel/apm_32.c.
1da177e4 356
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357 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
358 Format: <io>,<irq>,<nodeID>
359
360 ataflop= [HW,M68k]
361
362 atarimouse= [HW,MOUSE] Atari Mouse
363
364 atascsi= [HW,SCSI] Atari SCSI
365
366 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
367 EzKey and similar keyboards
368
369 atkbd.reset= [HW] Reset keyboard during initialization
370
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371 atkbd.set= [HW] Select keyboard code set
372 Format: <int> (2 = AT (default), 3 = PS/2)
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373
374 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
375 keyboards
376
377 atkbd.softraw= [HW] Choose between synthetic and real raw mode
378 Format: <bool> (0 = real, 1 = synthetic (default))
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379
380 atkbd.softrepeat= [HW]
381 Use software keyboard repeat
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382
383 autotest [IA64]
384
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385 baycom_epp= [HW,AX25]
386 Format: <io>,<mode>
a9913044 387
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388 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
389 Format: <io>,<mode>
390 See header of drivers/net/hamradio/baycom_par.c.
391
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392 baycom_ser_fdx= [HW,AX25]
393 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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394 Format: <io>,<irq>,<mode>[,<baud>]
395 See header of drivers/net/hamradio/baycom_ser_fdx.c.
396
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397 baycom_ser_hdx= [HW,AX25]
398 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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399 Format: <io>,<irq>,<mode>
400 See header of drivers/net/hamradio/baycom_ser_hdx.c.
401
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402 boot_delay= Milliseconds to delay each printk during boot.
403 Values larger than 10 seconds (10000) are changed to
404 no delay (0).
405 Format: integer
406
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407 bootmem_debug [KNL] Enable bootmem allocator debug messages.
408
1da177e4 409 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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410 bttv.radio= Most important insmod options are available as
411 kernel args too.
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412 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
413 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
414
415 BusLogic= [HW,SCSI]
416 See drivers/scsi/BusLogic.c, comment before function
417 BusLogic_ParseDriverOptions().
418
419 c101= [NET] Moxa C101 synchronous serial card
420
cd4f0ef7 421 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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422 Sometimes CPU hardware bugs make them report the cache
423 size incorrectly. The kernel will attempt work arounds
424 to fix known problems, but for some CPUs it is not
425 possible to determine what the correct size should be.
426 This option provides an override for these situations.
427
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428 capability.disable=
429 [SECURITY] Disable capabilities. This would normally
430 be used only if an alternative security model is to be
431 configured. Potentially dangerous and should only be
432 used if you are entirely sure of the consequences.
433
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434 ccw_timeout_log [S390]
435 See Documentation/s390/CommonIO for details.
1da177e4 436
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437 cgroup_disable= [KNL] Disable a particular controller
438 Format: {name of the controller(s) to disable}
439 {Currently supported controllers - "memory"}
440
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441 checkreqprot [SELINUX] Set initial checkreqprot flag value.
442 Format: { "0" | "1" }
443 See security/selinux/Kconfig help text.
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444 0 -- check protection applied by kernel (includes
445 any implied execute protection).
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446 1 -- check protection requested by application.
447 Default value is set via a kernel config option.
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448 Value can be changed at runtime via
449 /selinux/checkreqprot.
450
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451 cio_ignore= [S390]
452 See Documentation/s390/CommonIO for details.
453
cd4f0ef7 454 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 455 [Deprecated]
3f6dee9b 456 Forces specified clocksource (if available) to be used
734efb46 457 when calculating gettimeofday(). If specified
3f6dee9b 458 clocksource is not available, it defaults to PIT.
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459 Format: { pit | tsc | cyclone | pmtmr }
460
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461 clocksource= [GENERIC_TIME] Override the default clocksource
462 Format: <string>
463 Override the default clocksource and use the clocksource
464 with the name specified.
465 Some clocksource names to choose from, depending on
466 the platform:
467 [all] jiffies (this is the base, fallback clocksource)
468 [ACPI] acpi_pm
469 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
470 pxa_timer,timer3,32k_counter,timer0_1
471 [AVR32] avr32
cd4f0ef7 472 [X86-32] pit,hpet,tsc,vmi-timer;
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473 scx200_hrt on Geode; cyclone on IBM x440
474 [MIPS] MIPS
475 [PARISC] cr16
476 [S390] tod
477 [SH] SuperH
478 [SPARC64] tick
479 [X86-64] hpet,tsc
480
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481 clearcpuid=BITNUM [X86]
482 Disable CPUID feature X for the kernel. See
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483 arch/x86/include/asm/cpufeature.h for the valid bit
484 numbers. Note the Linux specific bits are not necessarily
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485 stable over kernel options, but the vendor specific
486 ones should be.
487 Also note that user programs calling CPUID directly
488 or using the feature without checking anything
489 will still see it. This just prevents it from
490 being used by the kernel or shown in /proc/cpuinfo.
491 Also note the kernel might malfunction if you disable
492 some critical bits.
493
6cececfc 494 code_bytes [X86] How many bytes of object code to print
a25bd949 495 in an oops report.
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496 Range: 0 - 8192
497 Default: 64
498
1da177e4 499 com20020= [HW,NET] ARCnet - COM20020 chipset
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500 Format:
501 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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502
503 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
504 Format: <io>[,<irq>]
505
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506 com90xx= [HW,NET]
507 ARCnet - COM90xx chipset (memory-mapped buffers)
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508 Format: <io>[,<irq>[,<memstart>]]
509
510 condev= [HW,S390] console device
511 conmode=
a9913044 512
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513 console= [KNL] Output console device and options.
514
515 tty<n> Use the virtual console device <n>.
516
517 ttyS<n>[,options]
f1a1c2dc 518 ttyUSB0[,options]
1da177e4 519 Use the specified serial port. The options are of
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520 the form "bbbbpnf", where "bbbb" is the baud rate,
521 "p" is parity ("n", "o", or "e"), "n" is number of
522 bits, and "f" is flow control ("r" for RTS or
523 omit it). Default is "9600n8".
524
525 See Documentation/serial-console.txt for more
526 information. See
527 Documentation/networking/netconsole.txt for an
528 alternative.
1da177e4 529
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530 uart[8250],io,<addr>[,options]
531 uart[8250],mmio,<addr>[,options]
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LT
532 Start an early, polled-mode console on the 8250/16550
533 UART at the specified I/O port or MMIO address,
534 switching to the matching ttyS device later. The
535 options are the same as for ttyS, above.
536
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ST
537 If the device connected to the port is not a TTY but a braille
538 device, prepend "brl," before the device type, for instance
539 console=brl,ttyS0
540 For now, only VisioBraille is supported.
541
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542 coredump_filter=
543 [KNL] Change the default value for
544 /proc/<pid>/coredump_filter.
545 See also Documentation/filesystems/proc.txt.
546
1da177e4 547 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
548 Format:
549 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 550
dc009d92
EB
551 crashkernel=nn[KMG]@ss[KMG]
552 [KNL] Reserve a chunk of physical memory to
553 hold a kernel to switch to with kexec on panic.
554
fb391599
BW
555 crashkernel=range1:size1[,range2:size2,...][@offset]
556 [KNL] Same as above, but depends on the memory
557 in the running system. The syntax of range is
558 start-[end] where start and end are both
559 a memory unit (amount[KMG]). See also
560 Documentation/kdump/kdump.txt for a example.
561
1da177e4
LT
562 cs89x0_dma= [HW,NET]
563 Format: <dma>
564
565 cs89x0_media= [HW,NET]
566 Format: { rj45 | aui | bnc }
a9913044 567
a9913044 568 dasd= [HW,NET]
1da177e4
LT
569 See header of drivers/s390/block/dasd_devmap.c.
570
571 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
572 (one device per port)
573 Format: <port#>,<type>
574 See also Documentation/input/joystick-parport.txt
575
576 debug [KNL] Enable kernel debugging (events log level).
577
cae2ed9a
IM
578 debug_locks_verbose=
579 [KNL] verbose self-tests
580 Format=<0|1>
581 Print debugging info while doing the locking API
582 self-tests.
583 We default to 0 (no extra messages), setting it to
584 1 will print _a lot_ more information - normally
585 only useful to kernel developers.
586
3ac7fe5a
TG
587 debug_objects [KNL] Enable object debugging
588
3e8ebb5c
KM
589 no_debug_objects
590 [KNL] Disable object debugging
591
d3af01f1
TG
592 debugpat [X86] Enable PAT debugging
593
2d27a966 594 decnet.addr= [HW,NET]
1da177e4
LT
595 Format: <area>[,<node>]
596 See also Documentation/networking/decnet.txt.
597
0cb55ad2
RD
598 default_hugepagesz=
599 [same as hugepagesz=] The size of the default
600 HugeTLB page size. This is the size represented by
601 the legacy /proc/ hugepages APIs, used for SHM, and
602 default size when mounting hugetlbfs filesystems.
603 Defaults to the default architecture's huge page size
604 if not specified.
55ff9780 605
1da177e4
LT
606 dhash_entries= [KNL]
607 Set number of hash buckets for dentry cache.
a9913044 608
1da177e4
LT
609 digi= [HW,SERIAL]
610 IO parameters + enable/disable command.
611
612 digiepca= [HW,SERIAL]
613 See drivers/char/README.epca and
31c00fc1 614 Documentation/serial/digiepca.txt.
1da177e4 615
95ffa243 616 disable_mtrr_cleanup [X86]
95ffa243
YL
617 The kernel tries to adjust MTRR layout from continuous
618 to discrete, to make X server driver able to add WB
0cb55ad2 619 entry later. This parameter disables that.
95ffa243 620
093af8d7 621 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
622 By default the kernel will trim any uncacheable
623 memory out of your available memory pool based on
624 MTRR settings. This parameter disables that behavior,
625 possibly causing your machine to run very slowly.
626
6cececfc 627 disable_timer_pin_1 [X86]
0cb55ad2
RD
628 Disable PIN 1 of APIC timer
629 Can be useful to work around chipset bugs.
630
1da177e4
LT
631 dmasound= [HW,OSS] Sound subsystem buffers
632
0cb55ad2
RD
633 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
634 this option disables the debugging code at boot.
635
636 dma_debug_entries=<number>
637 This option allows to tune the number of preallocated
638 entries for DMA-API debugging code. One entry is
639 required per DMA-API allocation. Use this if the
640 DMA-API debugging code disables itself because the
641 architectural default is too low.
642
1da177e4
LT
643 dscc4.setup= [NET]
644
645 dtc3181e= [HW,SCSI]
646
0cb55ad2
RD
647 dynamic_printk Enables pr_debug()/dev_dbg() calls if
648 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
649 These can also be switched on/off via
650 <debugfs>/dynamic_printk/modules
651
652 earlycon= [KNL] Output early console device and options.
653 uart[8250],io,<addr>[,options]
654 uart[8250],mmio,<addr>[,options]
655 Start an early, polled-mode console on the 8250/16550
656 UART at the specified I/O port or MMIO address.
657 The options are the same as for ttyS, above.
658
6cececfc 659 earlyprintk= [X86,SH,BLACKFIN]
1da177e4
LT
660 earlyprintk=vga
661 earlyprintk=serial[,ttySn[,baudrate]]
5c05917e 662 earlyprintk=dbgp
1da177e4 663
a9913044 664 Append ",keep" to not disable it when the real console
1da177e4
LT
665 takes over.
666
5c05917e 667 Only vga or serial or usb debug port at a time.
1da177e4
LT
668
669 Currently only ttyS0 and ttyS1 are supported.
670
671 Interaction with the standard serial driver is not
672 very good.
673
674 The VGA output is eventually overwritten by the real
675 console.
676
677 eata= [HW,SCSI]
678
1da177e4 679 edd= [EDD]
8c4dd606 680 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 681
1da177e4
LT
682 eisa_irq_edge= [PARISC,HW]
683 See header of drivers/parisc/eisa.c.
684
cd4f0ef7 685 elanfreq= [X86-32]
1da177e4 686 See comment before function elanfreq_setup() in
71f77055 687 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
688
689 elevator= [IOSCHED]
16ab3adf 690 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
691 See Documentation/block/as-iosched.txt and
692 Documentation/block/deadline-iosched.txt for details.
693
6cececfc 694 elfcorehdr= [IA64,PPC,SH,X86]
a9913044 695 Specifies physical address of start of kernel core
aac04b32
VG
696 image elf header. Generally kexec loader will
697 pass this option to capture kernel.
698 See Documentation/kdump/kdump.txt for details.
1da177e4 699
0cb55ad2
RD
700 enable_mtrr_cleanup [X86]
701 The kernel tries to adjust MTRR layout from continuous
702 to discrete, to make X server driver able to add WB
703 entry later. This parameter enables that.
704
705 enable_timer_pin_1 [i386,x86-64]
706 Enable PIN 1 of APIC timer
707 Can be useful to work around chipset bugs
708 (in particular on some ATI chipsets).
709 The kernel tries to set a reasonable default.
710
1da177e4
LT
711 enforcing [SELINUX] Set initial enforcing status.
712 Format: {"0" | "1"}
713 See security/selinux/Kconfig help text.
714 0 -- permissive (log only, no denials).
715 1 -- enforcing (deny and log).
716 Default value is 0.
717 Value can be changed at runtime via /selinux/enforce.
718
1da177e4
LT
719 ether= [HW,NET] Ethernet cards parameters
720 This option is obsoleted by the "netdev=" option, which
721 has equivalent usage. See its documentation for details.
722
723 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
724 Format: <io>[,<irq>]
725
de1ba09b
AM
726 failslab=
727 fail_page_alloc=
728 fail_make_request=[KNL]
729 General fault injection mechanism.
730 Format: <interval>,<probability>,<space>,<times>
731 See also /Documentation/fault-injection/.
732
1da177e4
LT
733 fd_mcs= [HW,SCSI]
734 See header of drivers/scsi/fd_mcs.c.
735
736 fdomain= [HW,SCSI]
737 See header of drivers/scsi/fdomain.c.
738
739 floppy= [HW]
31c00fc1 740 See Documentation/blockdev/floppy.txt.
1da177e4 741
f13ae30e
AC
742 force_pal_cache_flush
743 [IA-64] Avoid check_sal_cache_flush which may hang on
744 buggy SAL_CACHE_FLUSH implementations. Using this
745 parameter will force ia64_sal_cache_flush to call
746 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
747
d9e54076
PZ
748 ftrace=[tracer]
749 [ftrace] will set and start the specified tracer
750 as early as possible in order to facilitate early
751 boot debugging.
752
753 ftrace_dump_on_oops
754 [ftrace] will dump the trace buffers on oops.
755
1da177e4
LT
756 gamecon.map[2|3]=
757 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
758 support via parallel port (up to 5 devices per port)
759 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
760 See also Documentation/input/joystick-parport.txt
761
762 gamma= [HW,DRM]
763
aaf23042
YL
764 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
765 Format: off | on
766 default: on
767
1da177e4
LT
768 gdth= [HW,SCSI]
769 See header of drivers/scsi/gdth.c.
770
771 gpt [EFI] Forces disk with valid GPT signature but
772 invalid Protective MBR to be treated as GPT.
773
1da177e4
LT
774 gvp11= [HW,SCSI]
775
776 hashdist= [KNL,NUMA] Large hashes allocated during boot
777 are distributed across NUMA nodes. Defaults on
429aa0fc 778 for 64bit NUMA, off otherwise.
a9913044 779 Format: 0 | 1 (for off | on)
1da177e4
LT
780
781 hcl= [IA-64] SGI's Hardware Graph compatibility layer
782
783 hd= [EIDE] (E)IDE hard drive subsystem geometry
784 Format: <cyl>,<head>,<sect>
785
1da177e4
LT
786 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
787 size of <nn>. This works even on boxes that have no
788 highmem otherwise. This also works to reduce highmem
789 size on bigger boxes.
790
54cdfdb4
TG
791 highres= [KNL] Enable/disable high resolution timer mode.
792 Valid parameters: "on", "off"
793 Default: "on"
794
1da177e4
LT
795 hisax= [HW,ISDN]
796 See Documentation/isdn/README.HiSax.
797
0cb55ad2
RD
798 hlt [BUGS=ARM,SH]
799
800 hpet= [X86-32,HPET] option to control HPET usage
801 Format: { enable (default) | disable | force |
802 verbose }
803 disable: disable HPET and use PIT instead
804 force: allow force enabled of undocumented chips (ICH4,
805 VIA, nVidia)
806 verbose: show contents of HPET registers during setup
807
b4718e62
AK
808 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
809 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
810 On x86-64 and powerpc, this option can be specified
811 multiple times interleaved with hugepages= to reserve
812 huge pages of different sizes. Valid pages sizes on
813 x86-64 are 2M (when the CPU supports "pse") and 1G
814 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
815 Note that 1GB pages can only be allocated at boot time
816 using hugepages= and not freed afterwards.
6902aa84 817
555d61d6
HB
818 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
819 terminal devices. Valid values: 0..8
431429ff
HB
820 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
821 If specified, z/VM IUCV HVC accepts connections
822 from listed z/VM user IDs only.
cef7125d 823
3a853fb9 824 i2c_bus= [HW] Override the default board specific I2C bus speed
7954763b
JN
825 or register an additional I2C bus that is not
826 registered from board initialization code.
3a853fb9
JN
827 Format:
828 <bus_id>,<clkrate>
829
36d95739 830 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 831 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
832 i8042.dumbkbd [HW] Pretend that controller can only read data from
833 keyboard and cannot control its state
1da177e4
LT
834 (Don't attempt to blink the leds)
835 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 836 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
837 i8042.noloop [HW] Disable the AUX Loopback command while probing
838 for the AUX port
1da177e4
LT
839 i8042.nomux [HW] Don't check presence of an active multiplexing
840 controller
841 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
842 controllers
843 i8042.panicblink=
844 [HW] Frequency with which keyboard LEDs should blink
845 when kernel panics (default is 0.5 sec)
846 i8042.reset [HW] Reset the controller during init and cleanup
847 i8042.unlock [HW] Unlock (ignore) the keylock
848
849 i810= [HW,DRM]
850
e70c9d5e
DT
851 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
852 indicates that the driver is running on unsupported
853 hardware.
1da177e4
LT
854 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
855 does not match list of supported models.
856 i8k.power_status
857 [HW] Report power status in /proc/i8k
858 (disabled by default)
859 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
860 capability is set.
861
862 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
863 See Documentation/mca.txt.
864
865 icn= [HW,ISDN]
866 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
867
0af80c04
DF
868 ide-core.nodma= [HW] (E)IDE subsystem
869 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
870 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
871 .chs .ignore_cable are additional options
1c10e938 872 See Documentation/ide/ide.txt.
1da177e4 873
1da177e4 874 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
1c10e938 875 See Documentation/ide/ide.txt.
1da177e4 876
0cb55ad2
RD
877 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
878 Claim all unknown PCI IDE storage controllers.
879
f039b754 880 idle= [X86]
ada9cfdd
RD
881 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
882 Poll forces a polling idle loop that can slightly
883 improve the performance of waking up a idle CPU, but
884 will use a lot of power and make the system run hot.
885 Not recommended.
886 idle=mwait: On systems which support MONITOR/MWAIT but
887 the kernel chose to not use it because it doesn't save
888 as much power as a normal idle loop, use the
889 MONITOR/MWAIT idle loop anyways. Performance should be
890 the same as idle=poll.
891 idle=halt: Halt is forced to be used for CPU idle.
c1e3b377 892 In such case C2/C3 won't be used again.
ada9cfdd 893 idle=nomwait: Disable mwait for CPU C-states
a9913044 894
79290822
IM
895 ignore_loglevel [KNL]
896 Ignore loglevel setting - this will print /all/
897 kernel messages to the console. Useful for debugging.
898
1da177e4
LT
899 ihash_entries= [KNL]
900 Set number of hash buckets for inode cache.
901
3323eec9
MZ
902 ima_audit= [IMA]
903 Format: { "0" | "1" }
904 0 -- integrity auditing messages. (Default)
905 1 -- enable informational integrity auditing messages.
906
907 ima_hash= [IMA]
908 Formt: { "sha1" | "md5" }
909 default: "sha1"
910
1da177e4
LT
911 in2000= [HW,SCSI]
912 See header of drivers/scsi/in2000.c.
913
914 init= [KNL]
915 Format: <full_path>
916 Run specified binary instead of /sbin/init as init
917 process.
918
919 initcall_debug [KNL] Trace initcalls as they are executed. Useful
920 for working out where the kernel is dying during
921 startup.
922
923 initrd= [BOOT] Specify the location of the initial ramdisk
924
925 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
926 Format: <irq>
927
ba395927 928 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
0cd5c3c8
KM
929 on
930 Enable intel iommu driver.
ba395927
KA
931 off
932 Disable intel iommu driver.
933 igfx_off [Default Off]
934 By default, gfx is mapped as normal device. If a gfx
935 device has a dedicated DMAR unit, the DMAR unit is
936 bypassed by not enabling DMAR with this option. In
937 this case, gfx device will use physical address for
938 DMA.
7d3b03ce
KA
939 forcedac [x86_64]
940 With this option iommu will not optimize to look
941 for io virtual address below 32 bit forcing dual
942 address cycle on pci bus for cards supporting greater
943 than 32 bit addressing. The default is to look
944 for translation below 32 bit and if not available
945 then look in the higher range.
5e0d2a6f 946 strict [Default Off]
947 With this option on every unmap_single operation will
948 result in a hardware IOTLB flush operation as opposed
949 to batching them for performance.
ba395927 950
0cb55ad2
RD
951 inttest= [IA64]
952
953 iomem= Disable strict checking of access to MMIO memory
954 strict regions from userspace.
955 relaxed
956
957 iommu= [x86]
958 off
959 force
960 noforce
961 biomerge
962 panic
963 nopanic
964 merge
965 nomerge
966 forcesac
967 soft
968
969 io7= [HW] IO7 for Marvel based alpha systems
970 See comment before marvel_specify_io7 in
971 arch/alpha/kernel/core_marvel.c.
972
6cececfc 973 io_delay= [X86] I/O delay method
6e7c4025
IM
974 0x80
975 Standard port 0x80 based delay
976 0xed
977 Alternate port 0xed based delay (needed on some systems)
b02aae9c 978 udelay
6e7c4025
IM
979 Simple two microseconds delay
980 none
981 No delay
b02aae9c 982
1da177e4 983 ip= [IP_PNP]
6ded55da 984 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
985
986 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
987 See comment before ip2_setup() in
988 drivers/char/ip2/ip2base.c.
1da177e4
LT
989
990 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
991 See header of drivers/scsi/ips.c.
992
200803df
AC
993 irqfixup [HW]
994 When an interrupt is not handled search all handlers
995 for it. Intended to get systems with badly broken
996 firmware running.
997
998 irqpoll [HW]
999 When an interrupt is not handled search all handlers
1000 for it. Also check all handlers each timer
1001 interrupt. Intended to get systems with badly broken
1002 firmware running.
1003
1da177e4 1004 isapnp= [ISAPNP]
a9913044 1005 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
1006
1007 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
1008 Format:
1009 <cpu number>,...,<cpu number>
1010 or
b225d44e
LZ
1011 <cpu number>-<cpu number>
1012 (must be a positive range in ascending order)
22f2e280
DF
1013 or a mixture
1014 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 1015
1da177e4
LT
1016 This option can be used to specify one or more CPUs
1017 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
1018 algorithms. You can move a process onto or off an
1019 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
1020 <cpu number> begins at 0 and the maximum value is
1021 "number of CPUs in system - 1".
1022
1023 This option is the preferred way to isolate CPUs. The
a9913044
RD
1024 alternative -- manually setting the CPU mask of all
1025 tasks in the system -- can cause problems and
1026 suboptimal load balancer performance.
1da177e4 1027
a9913044 1028 iucv= [HW,NET]
1da177e4
LT
1029
1030 js= [HW,JOY] Analog joystick
1031 See Documentation/input/joystick.txt.
1032
0cb55ad2
RD
1033 keepinitrd [HW,ARM]
1034
6cececfc 1035 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
ed7ed365
MG
1036 specifies the amount of memory usable by the kernel
1037 for non-movable allocations. The requested amount is
1038 spread evenly throughout all nodes in the system. The
1039 remaining memory in each node is used for Movable
1040 pages. In the event, a node is too small to have both
1041 kernelcore and Movable pages, kernelcore pages will
1042 take priority and other nodes will have a larger number
1043 of kernelcore pages. The Movable zone is used for the
1044 allocation of pages that may be reclaimed or moved
1045 by the page migration subsystem. This means that
1046 HugeTLB pages may not be allocated from this zone.
1047 Note that allocations like PTEs-from-HighMem still
1048 use the HighMem zone if it exists, and the Normal
1049 zone if it does not.
1050
b9ce08c0
EGM
1051 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
1052 Controls whether kmemtrace is enabled
1053 at boot-time.
1054
1055 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
1056 subbufs kmemtrace's relay channel has. Set this
1057 higher than default (KMEMTRACE_N_SUBBUFS in code) if
1058 you experience buffer overruns.
1059
6cdf6e06
JW
1060 kgdboc= [HW] kgdb over consoles.
1061 Requires a tty driver that supports console polling.
1062 (only serial suported for now)
1063 Format: <serial_device>[,baud]
1064
9bed90c6
FF
1065 kmac= [MIPS] korina ethernet MAC address.
1066 Configure the RouterBoard 532 series on-chip
1067 Ethernet adapter MAC address.
1068
6cececfc 1069 kstack=N [X86] Print N words from the kernel stack
0cb55ad2
RD
1070 in oops dumps.
1071
1da177e4
LT
1072 l2cr= [PPC]
1073
a78bfbfc
RB
1074 l3cr= [PPC]
1075
cd4f0ef7 1076 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1077 disabled it.
1da177e4 1078
6cececfc 1079 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
ada9cfdd 1080 in C2 power state.
e585bef8 1081
fcb71f6f
FC
1082 libata.dma= [LIBATA] DMA control
1083 libata.dma=0 Disable all PATA and SATA DMA
1084 libata.dma=1 PATA and SATA Disk DMA only
1085 libata.dma=2 ATAPI (CDROM) DMA only
1086 libata.dma=4 Compact Flash DMA only
1087 Combinations also work, so libata.dma=3 enables DMA
1088 for disks and CDROMs, but not CFs.
1089
78e70c23
DJ
1090 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1091 when set.
1092 Format: <int>
1093
33267325
TH
1094 libata.force= [LIBATA] Force configurations. The format is comma
1095 separated list of "[ID:]VAL" where ID is
1096 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1097 matching port, link or device. Basically, it matches
1098 the ATA ID string printed on console by libata. If
1099 the whole ID part is omitted, the last PORT and DEVICE
1100 values are used. If ID hasn't been specified yet, the
1101 configuration applies to all ports, links and devices.
1102
1103 If only DEVICE is omitted, the parameter applies to
1104 the port and all links and devices behind it. DEVICE
1105 number of 0 either selects the first device or the
1106 first fan-out link behind PMP device. It does not
1107 select the host link. DEVICE number of 15 selects the
1108 host link and device attached to it.
1109
1110 The VAL specifies the configuration to force. As long
1111 as there's no ambiguity shortcut notation is allowed.
1112 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1113 The following configurations can be forced.
1114
1115 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1116 Any ID with matching PORT is used.
1117
1118 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1119
1120 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1121 udma[/][16,25,33,44,66,100,133] notation is also
1122 allowed.
1123
1124 * [no]ncq: Turn on or off NCQ.
1125
05944bdf
TH
1126 * nohrst, nosrst, norst: suppress hard, soft
1127 and both resets.
1128
33267325
TH
1129 If there are multiple matching configurations changing
1130 the same attribute, the last one is used.
1131
7c4be253
RD
1132 lmb=debug [KNL] Enable lmb debug messages.
1133
1da177e4 1134 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1135 See Documentation/blockdev/ramdisk.txt.
1da177e4 1136
a6b25b67
RD
1137 lockd.nlm_grace_period=P [NFS] Assign grace period.
1138 Format: <integer>
1da177e4 1139
a6b25b67
RD
1140 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1141 Format: <integer>
1142
1143 lockd.nlm_timeout=T [NFS] Assign timeout value.
1144 Format: <integer>
1145
1146 lockd.nlm_udpport=M [NFS] Assign UDP port.
1147 Format: <integer>
1da177e4
LT
1148
1149 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1150 Format: <irq>
1151
1152 loglevel= All Kernel Messages with a loglevel smaller than the
1153 console loglevel will be printed to the console. It can
1154 also be changed with klogd or other programs. The
1155 loglevels are defined as follows:
1156
1157 0 (KERN_EMERG) system is unusable
1158 1 (KERN_ALERT) action must be taken immediately
1159 2 (KERN_CRIT) critical conditions
1160 3 (KERN_ERR) error conditions
1161 4 (KERN_WARNING) warning conditions
1162 5 (KERN_NOTICE) normal but significant condition
1163 6 (KERN_INFO) informational
1164 7 (KERN_DEBUG) debug-level messages
1165
1166 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1167 Format: { n | nk | nM }
1168 n must be a power of two. The default size
1169 is set in the kernel config file.
1da177e4 1170
accaa24c
RD
1171 logo.nologo [FB] Disables display of the built-in Linux logo.
1172 This may be used to provide more screen space for
1173 kernel log messages and is useful when debugging
1174 kernel boot problems.
1175
1da177e4
LT
1176 lp=0 [LP] Specify parallel ports to use, e.g,
1177 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1178 lp=reset first parallel port). 'lp=0' disables the
1179 lp=auto printer driver. 'lp=reset' (which can be
1180 specified in addition to the ports) causes
1181 attached printers to be reset. Using
1182 lp=port1,port2,... specifies the parallel ports
1183 to associate lp devices with, starting with
1184 lp0. A port specification may be 'none' to skip
1185 that lp device, or a parport name such as
1186 'parport0'. Specifying 'lp=auto' instead of a
1187 port specification list means that device IDs
1188 from each port should be examined, to see if
1189 an IEEE 1284-compliant printer is attached; if
1190 so, the driver will manage that printer.
1191 See also header of drivers/char/lp.c.
1192
1193 lpj=n [KNL]
1194 Sets loops_per_jiffy to given constant, thus avoiding
1195 time-consuming boot-time autodetection (up to 250 ms per
1196 CPU). 0 enables autodetection (default). To determine
1197 the correct value for your kernel, boot with normal
1198 autodetection and see what value is printed. Note that
1199 on SMP systems the preset will be applied to all CPUs,
1200 which is likely to cause problems if your CPUs need
1201 significantly divergent settings. An incorrect value
1202 will cause delays in the kernel to be wrong, leading to
1203 unpredictable I/O errors and other breakage. Although
1204 unlikely, in the extreme case this might damage your
1205 hardware.
1206
1207 ltpc= [NET]
1208 Format: <io>,<irq>,<dma>
1209
a9913044
RD
1210 mac5380= [HW,SCSI] Format:
1211 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1212
a9913044
RD
1213 machvec= [IA64] Force the use of a particular machine-vector
1214 (machvec) in a generic kernel.
1215 Example: machvec=hpzx1_swiotlb
1da177e4 1216
0cb55ad2
RD
1217 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1218 than or equal to this physical address is ignored.
1da177e4
LT
1219
1220 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1221 should make use of. maxcpus=n : n >= 0 limits the
1222 kernel to using 'n' processors. n=0 is a special case,
1223 it is equivalent to "nosmp", which also disables
1224 the IO APIC.
1da177e4 1225
0cb55ad2
RD
1226 max_loop= [LOOP] Maximum number of loopback devices that can
1227 be mounted
1228 Format: <1-256>
2b2c3750 1229
a9913044 1230 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1231 Should be between 1 and 2^32-1.
1232
1233 max_report_luns=
a9913044 1234 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1235 Should be between 1 and 16384.
1236
1da177e4
LT
1237 mcatest= [IA-64]
1238
cd4f0ef7 1239 mce [X86-32] Machine Check Exception
1da177e4 1240
71cced6e 1241 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1242
1da177e4
LT
1243 md= [HW] RAID subsystems devices and level
1244 See Documentation/md.txt.
a9913044 1245
1da177e4
LT
1246 mdacon= [MDA]
1247 Format: <first>,<last>
1248 Specifies range of consoles to be captured by the MDA.
a9913044 1249
1da177e4
LT
1250 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1251 Amount of memory to be used when the kernel is not able
1252 to see the whole system memory or for test.
cd4f0ef7 1253 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1254 address space collisions. Without memmap= PCI devices
1255 could be placed at addresses belonging to unused RAM.
1256
cd4f0ef7 1257 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1258 memory.
1259
6902aa84
PM
1260 memchunk=nn[KMG]
1261 [KNL,SH] Allow user to override the default size for
1262 per-device physically contiguous DMA buffers.
1263
6cececfc 1264 memmap=exactmap [KNL,X86] Enable setting of an exact
1da177e4
LT
1265 E820 memory map, as specified by the user.
1266 Such memmap=exactmap lines can be constructed based on
1267 BIOS output or other requirements. See the memmap=nn@ss
1268 option description.
1269
1270 memmap=nn[KMG]@ss[KMG]
1271 [KNL] Force usage of a specific region of memory
1272 Region of memory to be used, from ss to ss+nn.
1273
1274 memmap=nn[KMG]#ss[KMG]
1275 [KNL,ACPI] Mark specific memory as ACPI data.
1276 Region of memory to be used, from ss to ss+nn.
1277
1278 memmap=nn[KMG]$ss[KMG]
1279 [KNL,ACPI] Mark specific memory as reserved.
1280 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1281 Example: Exclude memory from 0x18690000-0x1869ffff
1282 memmap=64K$0x18690000
1283 or
1284 memmap=0x10000$0x18690000
1da177e4 1285
9f077871
JF
1286 memory_corruption_check=0/1 [X86]
1287 Some BIOSes seem to corrupt the first 64k of
1288 memory when doing things like suspend/resume.
1289 Setting this option will scan the memory
1290 looking for corruption. Enabling this will
1291 both detect corruption and prevent the kernel
1292 from using the memory being corrupted.
1293 However, its intended as a diagnostic tool; if
1294 repeatable BIOS-originated corruption always
1295 affects the same memory, you can use memmap=
1296 to prevent the kernel from using that memory.
1297
1298 memory_corruption_check_size=size [X86]
1299 By default it checks for corruption in the low
1300 64k, making this memory unavailable for normal
1301 use. Use this parameter to scan for
1302 corruption in more or less memory.
1303
1304 memory_corruption_check_period=seconds [X86]
1305 By default it checks for corruption every 60
1306 seconds. Use this parameter to check at some
1307 other rate. 0 disables periodic checking.
1308
caadbdce 1309 memtest= [KNL,X86] Enable memtest
c64df707 1310 Format: <integer>
c64df707 1311 default : 0 <disable>
9e5f6cf5
AH
1312 Specifies the number of memtest passes to be
1313 performed. Each pass selects another test
1314 pattern from a given set of patterns. Memtest
1315 fills the memory with this pattern, validates
1316 memory contents and reserves bad memory
1317 regions that are detected.
c64df707 1318
1da177e4
LT
1319 meye.*= [HW] Set MotionEye Camera parameters
1320 See Documentation/video4linux/meye.txt.
1321
8f36881b
AS
1322 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1323 Multi-Function General Purpose Timers on AMD Geode
1324 platforms.
1325
e6c4dc6c
WT
1326 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1327 the BIOS has incorrectly applied a workaround. TinyBIOS
1328 version 0.98 is known to be affected, 0.99 fixes the
1329 problem by letting the user disable the workaround.
1330
1da177e4
LT
1331 mga= [HW,DRM]
1332
1c207f95
RD
1333 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1334 physical address is ignored.
1335
6b74ab97
MG
1336 mminit_loglevel=
1337 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1338 parameter allows control of the logging verbosity for
1339 the additional memory initialisation checks. A value
1340 of 0 disables mminit logging and a level of 4 will
1341 log everything. Information is printed at KERN_DEBUG
1342 so loglevel=8 may also need to be specified.
1343
1da177e4
LT
1344 mousedev.tap_time=
1345 [MOUSE] Maximum time between finger touching and
1346 leaving touchpad surface for touch to be considered
1347 a tap and be reported as a left button click (for
1348 touchpads working in absolute mode only).
1349 Format: <msecs>
1350 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1351 reporting absolute coordinates, such as tablets
1352 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1353 reporting absolute coordinates, such as tablets
1354
6cececfc 1355 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
0cb55ad2
RD
1356 is similar to kernelcore except it specifies the
1357 amount of memory used for migratable allocations.
1358 If both kernelcore and movablecore is specified,
1359 then kernelcore will be at *least* the specified
1360 value but may be more. If movablecore on its own
1361 is specified, the administrator must be careful
1362 that the amount of memory usable for all allocations
1363 is not too small.
1364
1da177e4
LT
1365 mpu401= [HW,OSS]
1366 Format: <io>,<irq>
1367
1368 MTD_Partition= [MTD]
1369 Format: <name>,<region-number>,<size>,<offset>
1370
a9913044
RD
1371 MTD_Region= [MTD] Format:
1372 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1373
1374 mtdparts= [MTD]
c8facbb6 1375 See drivers/mtd/cmdlinepart.c.
1da177e4 1376
9db829f4
BD
1377 mtdset= [ARM]
1378 ARM/S3C2412 JIVE boot control
1379
1380 See arch/arm/mach-s3c2412/mach-jive.c
1381
1da177e4 1382 mtouchusb.raw_coordinates=
a9913044
RD
1383 [HW] Make the MicroTouch USB driver use raw coordinates
1384 ('y', default) or cooked coordinates ('n')
1da177e4 1385
0cb55ad2
RD
1386 mtrr_chunk_size=nn[KMG] [X86]
1387 used for mtrr cleanup. It is largest continous chunk
1388 that could hold holes aka. UC entries.
1389
1390 mtrr_gran_size=nn[KMG] [X86]
1391 Used for mtrr cleanup. It is granularity of mtrr block.
1392 Default is 1.
1393 Large value could prevent small alignment from
1394 using up MTRRs.
1395
1396 mtrr_spare_reg_nr=n [X86]
1397 Format: <integer>
1398 Range: 0,7 : spare reg number
1399 Default : 1
1400 Used for mtrr cleanup. It is spare mtrr entries number.
1401 Set to 2 or more if your graphical card needs more.
1402
1da177e4
LT
1403 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1404
1405 NCR_D700= [HW,SCSI]
1406 See header of drivers/scsi/NCR_D700.c.
1407
1408 ncr5380= [HW,SCSI]
1409
1410 ncr53c400= [HW,SCSI]
1411
1412 ncr53c400a= [HW,SCSI]
1413
1414 ncr53c406a= [HW,SCSI]
1415
1416 ncr53c8xx= [HW,SCSI]
1417
1418 netdev= [NET] Network devices parameters
1419 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1420 Note that mem_start is often overloaded to mean
1421 something different and driver-specific.
a9913044
RD
1422 This usage is only documented in each driver source
1423 file if at all.
1424
58401572
KPO
1425 nf_conntrack.acct=
1426 [NETFILTER] Enable connection tracking flow accounting
1427 0 to disable accounting
1428 1 to enable accounting
1429 Default value depends on CONFIG_NF_CT_ACCT that is
1430 going to be removed in 2.6.29.
1431
1da177e4 1432 nfsaddrs= [NFS]
6ded55da 1433 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
1434
1435 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
6ded55da 1436 See Documentation/filesystems/nfsroot.txt.
1da177e4 1437
a72b4422
TM
1438 nfs.callback_tcpport=
1439 [NFS] set the TCP port on which the NFSv4 callback
1440 channel should listen.
1441
58df095b
TM
1442 nfs.idmap_cache_timeout=
1443 [NFS] set the maximum lifetime for idmapper cache
1444 entries.
1445
f43bf0be
TM
1446 nfs.enable_ino64=
1447 [NFS] enable 64-bit inode numbers.
1448 If zero, the NFS client will fake up a 32-bit inode
1449 number for the readdir() and stat() syscalls instead
1450 of returning the full 64-bit number.
1451 The default is to return 64-bit inode numbers.
1452
e7ba176b
HS
1453 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1454 when a NMI is triggered.
1455 Format: [state][,regs][,debounce][,die]
1456
6cececfc 1457 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
5b9a0e14
CG
1458 Format: [panic,][num]
1459 Valid num: 0,1,2
1460 0 - turn nmi_watchdog off
1461 1 - use the IO-APIC timer for the NMI watchdog
1462 2 - use the local APIC for the NMI watchdog using
0cb55ad2
RD
1463 a performance counter. Note: This will use one
1464 performance counter and the local APIC's performance
1465 vector.
1466 When panic is specified, panic when an NMI watchdog
1467 timeout occurs.
1468 This is useful when you use a panic=... timeout and
1469 need the box quickly up again.
5b9a0e14
CG
1470 Instead of 1 and 2 it is possible to use the following
1471 symbolic names: lapic and ioapic
1472 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1da177e4 1473
cd4f0ef7 1474 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1475 emulation library even if a 387 maths coprocessor
1476 is present.
1477
0cb55ad2
RD
1478 no_console_suspend
1479 [HW] Never suspend the console
1480 Disable suspending of consoles during suspend and
1481 hibernate operations. Once disabled, debugging
1482 messages can reach various consoles while the rest
1483 of the system is being put to sleep (ie, while
1484 debugging driver suspend/resume hooks). This may
1485 not work reliably with all consoles, but is known
1486 to work with serial and VGA consoles.
1487
c1aee215
CL
1488 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1489 caches in the slab allocator. Saves per-node memory,
1490 but will impact performance.
3395ee05 1491
a9913044
RD
1492 noalign [KNL,ARM]
1493
1da177e4
LT
1494 noapic [SMP,APIC] Tells the kernel to not make use of any
1495 IOAPICs that may be present in the system.
1496
1da177e4
LT
1497 nobats [PPC] Do not use BATs for mapping kernel lowmem
1498 on "Classic" PPC cores.
1499
1500 nocache [ARM]
a9913044 1501
0cb55ad2
RD
1502 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1503
163ecdff
SN
1504 nodelayacct [KNL] Disable per-task delay accounting
1505
1da177e4
LT
1506 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1507
6902aa84
PM
1508 nodsp [SH] Disable hardware DSP at boot time.
1509
6cececfc 1510 noefi [X86] Disable EFI runtime services support.
8b2cb7a8 1511
1da177e4
LT
1512 noexec [IA-64]
1513
6cececfc 1514 noexec [X86]
f5a1b191 1515 On X86-32 available only on PAE configured kernels.
1da177e4 1516 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1517 noexec=off: disable non-executable mappings
1518
1519 noexec32 [X86-64]
1520 This affects only 32-bit executables.
1521 noexec32=on: enable non-executable mappings (default)
1522 read doesn't imply executable mappings
1523 noexec32=off: disable non-executable mappings
1524 read implies executable mappings
1da177e4 1525
6902aa84
PM
1526 nofpu [SH] Disable hardware FPU at boot time.
1527
cd4f0ef7 1528 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1529 register save and restore. The kernel will only save
1530 legacy floating-point registers on task switch.
1da177e4 1531
01a24d2b
PZ
1532 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1533 wfi(ARM) instruction doesn't work correctly and not to
1534 use it. This is also useful when using JTAG debugger.
a9913044 1535
cd4f0ef7 1536 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1537 instruction doesn't work correctly and not to
1538 use it.
1539
1f29fae2
SH
1540 no_file_caps Tells the kernel not to honor file capabilities. The
1541 only way then for a file to be executed with privilege
1542 is to be setuid root or executed by root.
1543
1da177e4
LT
1544 nohalt [IA-64] Tells the kernel not to use the power saving
1545 function PAL_HALT_LIGHT when idle. This increases
1546 power-consumption. On the positive side, it reduces
1547 interrupt wake-up latency, which may improve performance
1548 in certain environments such as networked servers or
1549 real-time systems.
1550
79bf2bb3
TG
1551 nohz= [KNL] Boottime enable/disable dynamic ticks
1552 Valid arguments: on, off
1553 Default: on
1554
eeee7853
PM
1555 noiotrap [SH] Disables trapped I/O port accesses.
1556
cd4f0ef7 1557 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1558 disable unhandled interrupt sources.
1559
6cececfc 1560 no_timer_check [X86,APIC] Disables the code which tests for
8542b200
ZA
1561 broken timer IRQ sources.
1562
1da177e4
LT
1563 noisapnp [ISAPNP] Disables ISA PnP code.
1564
1565 noinitrd [RAM] Tells the kernel not to load any configured
1566 initial RAM disk.
1567
1568 nointroute [IA-64]
1569
0aa366f3
TL
1570 nojitter [IA64] Disables jitter checking for ITC timers.
1571
cd4f0ef7 1572 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1573
cd4f0ef7 1574 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1575
1da177e4
LT
1576 noltlbs [PPC] Do not use large page/tlb entries for kernel
1577 lowmem mapping on PPC40x.
1578
312f1f01
H
1579 nomca [IA-64] Disable machine check abort handling
1580
cd4f0ef7 1581 nomce [X86-32] Machine Check Exception
abe37e5a 1582
83d7384f
AS
1583 nomfgpt [X86-32] Disable Multi-Function General Purpose
1584 Timer usage (for AMD Geode machines).
1585
0cb55ad2
RD
1586 norandmaps Don't use address space randomization. Equivalent to
1587 echo 0 > /proc/sys/kernel/randomize_va_space
1588
cd4f0ef7 1589 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1590
cd4f0ef7 1591 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1592 with UP alternatives
1593
1da177e4
LT
1594 noresidual [PPC] Don't use residual data on PReP machines.
1595
a9913044
RD
1596 noresume [SWSUSP] Disables resume and restores original swap
1597 space.
1598
1da177e4
LT
1599 no-scroll [VGA] Disables scrollback.
1600 This is required for the Braillex ib80-piezo Braille
1601 reader made by F.H. Papenmeier (Germany).
1602
1603 nosbagart [IA-64]
1604
cd4f0ef7 1605 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1606
61ec7567
LB
1607 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1608 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1609
97842216
DJ
1610 nosoftlockup [KNL] Disable the soft-lockup detector.
1611
c077719b 1612 noswapaccount [KNL] Disable accounting of swap in memory resource
21acb9ca 1613 controller. (See Documentation/cgroups/memory.txt)
c077719b 1614
1da177e4
LT
1615 nosync [HW,M68K] Disables sync negotiation for all devices.
1616
cd4f0ef7 1617 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1618
1619 nousb [USB] Disable the USB subsystem
1620
1621 nowb [ARM]
a9913044 1622
8b5b94e4
WH
1623 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1624
a6c75b86
FY
1625 nptcg= [IA64] Override max number of concurrent global TLB
1626 purges which is reported from either PAL_VM_SUMMARY or
1627 SAL PALO.
1628
0cb55ad2
RD
1629 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1630
f0c0b2b8
KH
1631 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1632 one of ['zone', 'node', 'default'] can be specified
1633 This can be set from sysctl after boot.
1634 See Documentation/sysctl/vm.txt for details.
1635
7c4be253
RD
1636 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1637 See Documentation/debugging-via-ohci1394.txt for more
1638 info.
1639
3ef0e1f8
AS
1640 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1641 Rather than timing out after 20 ms if an EC
1642 command is not properly ACKed, override the length
1643 of the timeout. We have interrupts disabled while
1644 waiting for the ACK, so if this is set too high
1645 interrupts *may* be lost!
1646
1da177e4
LT
1647 opl3= [HW,OSS]
1648 Format: <io>
1649
1da177e4
LT
1650 oprofile.timer= [HW]
1651 Use timer interrupt instead of performance counters
1652
1da177e4
LT
1653 osst= [HW,SCSI] SCSI Tape Driver
1654 Format: <buffer_size>,<write_threshold>
1655 See also Documentation/scsi/st.txt.
1656
1657 panic= [KNL] Kernel behaviour on panic
1658 Format: <timeout>
1659
1660 parkbd.port= [HW] Parallel port number the keyboard adapter is
1661 connected to, default is 0.
1662 Format: <parport#>
1663 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1664 0 for XT, 1 for AT (default is AT).
a9913044
RD
1665 Format: <mode>
1666
1667 parport= [HW,PPT] Specify parallel ports. 0 disables.
1668 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1669 Use 'auto' to force the driver to use any
1670 IRQ/DMA settings detected (the default is to
1671 ignore detected IRQ/DMA settings because of
1672 possible conflicts). You can specify the base
1673 address, IRQ, and DMA settings; IRQ and DMA
1674 should be numbers, or 'auto' (for using detected
1675 settings on that particular port), or 'nofifo'
1676 (to avoid using a FIFO even if it is detected).
1677 Parallel ports are assigned in the order they
1678 are specified on the command line, starting
1679 with parport0.
1680
1681 parport_init_mode= [HW,PPT]
1682 Configure VIA parallel port to operate in
1683 a specific mode. This is necessary on Pegasos
1684 computer where firmware has no options for setting
1685 up parallel port mode and sets it to spp.
1686 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1687 Format: [spp|ps2|epp|ecp|ecpepp]
1688
a9913044
RD
1689 pas2= [HW,OSS] Format:
1690 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1691
1da177e4
LT
1692 pas16= [HW,SCSI]
1693 See header of drivers/scsi/pas16.c.
1694
dd287796
AM
1695 pause_on_oops=
1696 Halt all CPUs after the first oops has been printed for
1697 the specified number of seconds. This is to be used if
1698 your oopses keep scrolling off the screen.
1699
1da177e4
LT
1700 pcbit= [HW,ISDN]
1701
1702 pcd. [PARIDE]
1703 See header of drivers/block/paride/pcd.c.
31c00fc1 1704 See also Documentation/blockdev/paride.txt.
1da177e4 1705
a9913044 1706 pci=option[,option...] [PCI] various PCI subsystem options:
1cc0ca26
BH
1707 earlydump [X86] dump PCI config space before the kernel
1708 changes anything
c0115606 1709 off [X86] don't probe for the PCI bus
cd4f0ef7 1710 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1711 the hardware directly. Use this if your machine
1712 has a non-standard PCI host bridge.
cd4f0ef7 1713 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1714 hardware access methods are allowed. Use this
1715 if you experience crashes upon bootup and you
1716 suspect they are caused by the BIOS.
c0115606 1717 conf1 [X86] Force use of PCI Configuration
a9913044 1718 Mechanism 1.
c0115606 1719 conf2 [X86] Force use of PCI Configuration
a9913044 1720 Mechanism 2.
7f785763
RD
1721 noaer [PCIE] If the PCIEAER kernel config parameter is
1722 enabled, this kernel boot option can be used to
1723 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1724 nodomains [PCI] Disable support for multiple PCI
1725 root domains (aka PCI segments, in ACPI-speak).
6cececfc 1726 nommconf [X86] Disable use of MMCONFIG for PCI
61be6d66 1727 Configuration
309e57df
MW
1728 nomsi [MSI] If the PCI_MSI kernel config parameter is
1729 enabled, this kernel boot option can be used to
1730 disable the use of MSI interrupts system-wide.
a9322f64
SA
1731 noioapicquirk [APIC] Disable all boot interrupt quirks.
1732 Safety option to keep boot IRQs enabled. This
1733 should never be necessary.
9197979b
SA
1734 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1735 primary IO-APIC for bridges that cannot disable
1736 boot IRQs. This fixes a source of spurious IRQs
1737 when the system masks IRQs.
41b9eb26
SA
1738 noioapicreroute [APIC] Disable workaround that uses the
1739 boot IRQ equivalent of an IRQ that connects to
1740 a chipset where boot IRQs cannot be disabled.
1741 The opposite of ioapicreroute.
cd4f0ef7 1742 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1743 routing table. These calls are known to be buggy
1744 on several machines and they hang the machine
1745 when used, but on other computers it's the only
1746 way to get the interrupt routing table. Try
1747 this option if the kernel is unable to allocate
1748 IRQs or discover secondary PCI buses on your
1749 motherboard.
c0115606 1750 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1751 Use with caution as certain devices share
1752 address decoders between ROMs and other
1753 resources.
c0115606 1754 norom [X86] Do not assign address space to
bb71ad88
GH
1755 expansion ROMs that do not already have
1756 BIOS assigned address ranges.
c0115606 1757 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1758 assigned automatically to PCI devices. You can
1759 make the kernel exclude IRQs of your ISA cards
1760 this way.
c0115606 1761 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1762 of the PIRQ table (normally generated
1763 by the BIOS) if it is outside the
1764 F0000h-100000h range.
c0115606 1765 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1766 useful if the kernel is unable to find your
1767 secondary buses and you want to tell it
1768 explicitly which ones they are.
c0115606 1769 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1770 numbers ourselves, overriding
1771 whatever the firmware may have done.
c0115606 1772 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1773 in the BIOS $PIR table. This is needed on
1774 some systems with broken BIOSes, notably
1775 some HP Pavilion N5400 and Omnibook XE3
1776 notebooks. This will have no effect if ACPI
1777 IRQ routing is enabled.
c0115606 1778 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1779 or for PCI scanning.
c0115606 1780 use_crs [X86] Use _CRS for PCI resource
62f420f8 1781 allocation.
a9913044
RD
1782 routeirq Do IRQ routing for all PCI devices.
1783 This is normally done in pci_enable_device(),
1784 so this option is a temporary workaround
1785 for broken drivers that don't call it.
13a6ddb0
YL
1786 skip_isa_align [X86] do not align io start addr, so can
1787 handle more pci cards
a9913044
RD
1788 firmware [ARM] Do not re-enumerate the bus but instead
1789 just use the configuration from the
1790 bootloader. This is currently used on
1791 IXP2000 systems where the bus has to be
1792 configured a certain way for adjunct CPUs.
0637a70a
AK
1793 noearly [X86] Don't do any early type 1 scanning.
1794 This might help on some broken boards which
1795 machine check when some devices' config space
1796 is read. But various workarounds are disabled
1797 and some IOMMU drivers will not work.
6b4b78fe
MD
1798 bfsort Sort PCI devices into breadth-first order.
1799 This sorting is done to get a device
1800 order compatible with older (<= 2.4) kernels.
1801 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1802 cbiosize=nn[KMG] The fixed amount of bus space which is
1803 reserved for the CardBus bridge's IO window.
1804 The default value is 256 bytes.
1805 cbmemsize=nn[KMG] The fixed amount of bus space which is
1806 reserved for the CardBus bridge's memory
1807 window. The default value is 64 megabytes.
32a9a682
YS
1808 resource_alignment=
1809 Format:
1810 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1811 Specifies alignment and device to reassign
1812 aligned memory resources.
1813 If <order of align> is not specified,
1814 PAGE_SIZE is used as alignment.
1815 PCI-PCI bridge can be specified, if resource
1816 windows need to be expanded.
6b4b78fe 1817
e5665a45
CE
1818 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1819 Management.
1820 off Disable ASPM.
1821 force Enable ASPM even on devices that claim not to support it.
1822 WARNING: Forcing ASPM on may cause system lockups.
1823
1da177e4
LT
1824 pcmv= [HW,PCMCIA] BadgePAD 4
1825
1826 pd. [PARIDE]
31c00fc1 1827 See Documentation/blockdev/paride.txt.
1da177e4
LT
1828
1829 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1830 boot time.
1831 Format: { 0 | 1 }
1832 See arch/parisc/kernel/pdc_chassis.c
1833
1834 pf. [PARIDE]
31c00fc1 1835 See Documentation/blockdev/paride.txt.
1da177e4
LT
1836
1837 pg. [PARIDE]
31c00fc1 1838 See Documentation/blockdev/paride.txt.
1da177e4
LT
1839
1840 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 1841 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
1842
1843 plip= [PPT,NET] Parallel port network link
1844 Format: { parport<nr> | timid | 0 }
1845 See also Documentation/parport.txt.
1846
de32a243
TG
1847 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1848 Override pmtimer IOPort with a hex value.
1849 e.g. pmtmr=0x508
1850
97ef062b
BH
1851 pnp.debug [PNP]
1852 Enable PNP debug messages. This depends on the
1853 CONFIG_PNP_DEBUG_MESSAGES option.
1854
1da177e4
LT
1855 pnpacpi= [ACPI]
1856 { off }
1857
1858 pnpbios= [ISAPNP]
1859 { on | off | curr | res | no-curr | no-res }
1860
1861 pnp_reserve_irq=
1862 [ISAPNP] Exclude IRQs for the autoconfiguration
1863
1864 pnp_reserve_dma=
1865 [ISAPNP] Exclude DMAs for the autoconfiguration
1866
1867 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1868 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1869
1870 pnp_reserve_mem=
a9913044
RD
1871 [ISAPNP] Exclude memory regions for the
1872 autoconfiguration.
1da177e4
LT
1873 Ranges are in pairs (memory base and size).
1874
4af94f39
RD
1875 ports= [IP_VS_FTP] IPVS ftp helper module
1876 Default is 21.
1877 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1878 may be specified.
1879 Format: <port>,<port>....
1880
45807a1d
IM
1881 print-fatal-signals=
1882 [KNL] debug: print fatal signals
1883 print-fatal-signals=1: print segfault info to
1884 the kernel console.
1885 default: off.
1886
e84845c4
RD
1887 printk.time= Show timing data prefixed to each printk message line
1888 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1889
0cb55ad2
RD
1890 processor.max_cstate= [HW,ACPI]
1891 Limit processor to maximum C-state
1892 max_cstate=9 overrides any DMI blacklist limit.
1893
1894 processor.nocst [HW,ACPI]
1895 Ignore the _CST method to determine C-states,
1896 instead using the legacy FADT method
1897
1da177e4 1898 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1899 Format: [schedule,]<number>
1900 Param: "schedule" - profile schedule points.
1901 Param: <number> - step/bucket size as a power of 2 for
1902 statistical time based profiling.
b3da2a73
MG
1903 Param: "sleep" - profile D-state sleeping (millisecs).
1904 Requires CONFIG_SCHEDSTATS
c0fe2e69 1905 Param: "kvm" - profile VM exits.
1da177e4 1906
1da177e4
LT
1907 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1908 before loading.
31c00fc1 1909 See Documentation/blockdev/ramdisk.txt.
1da177e4 1910
a9913044
RD
1911 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1912 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1913 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1914 per second.
a9913044
RD
1915 psmouse.resetafter= [HW,MOUSE]
1916 Try to reset the device after so many bad packets
1da177e4
LT
1917 (0 = never).
1918 psmouse.resolution=
1919 [HW,MOUSE] Set desired mouse resolution, in dpi.
1920 psmouse.smartscroll=
a9913044 1921 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1922 0 = disabled, 1 = enabled (default).
1923
1924 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1925 Format:
1926 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1927
1928 pt. [PARIDE]
31c00fc1 1929 See Documentation/blockdev/paride.txt.
1da177e4 1930
dc8c8587
KS
1931 pty.legacy_count=
1932 [KNL] Number of legacy pty's. Overwrites compiled-in
1933 default number.
1934
7d2c502f 1935 quiet [KNL] Disable most log messages
a9913044 1936
1da177e4
LT
1937 r128= [HW,DRM]
1938
1939 raid= [HW,RAID]
1940 See Documentation/md.txt.
1941
a9913044 1942 ramdisk_blocksize= [RAM]
31c00fc1 1943 See Documentation/blockdev/ramdisk.txt.
a9913044 1944
1da177e4 1945 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 1946 See Documentation/blockdev/ramdisk.txt.
1da177e4 1947
24aaef8d
RD
1948 rcupdate.blimit= [KNL,BOOT]
1949 Set maximum number of finished RCU callbacks to process
1950 in one batch.
21a1ea9e 1951
24aaef8d
RD
1952 rcupdate.qhimark= [KNL,BOOT]
1953 Set threshold of queued
21a1ea9e
DS
1954 RCU callbacks over which batch limiting is disabled.
1955
24aaef8d
RD
1956 rcupdate.qlowmark= [KNL,BOOT]
1957 Set threshold of queued RCU callbacks below which
1958 batch limiting is re-enabled.
21a1ea9e 1959
ffdfc409
OJ
1960 rdinit= [KNL]
1961 Format: <full_path>
1962 Run specified binary instead of /init from the ramdisk,
1963 used for early userspace startup. See initrd.
1964
cd4f0ef7 1965 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1966 Format: <reboot_mode>[,<reboot_mode2>[,...]]
ecb08d81 1967 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 1968
46b6d94e
PJ
1969 relax_domain_level=
1970 [KNL, SMP] Set scheduler's default relax_domain_level.
21acb9ca 1971 See Documentation/cgroups/cpusets.txt.
46b6d94e 1972
1da177e4
LT
1973 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1974
cd4f0ef7 1975 reservetop= [X86-32]
461a9aff
ZA
1976 Format: nn[KMG]
1977 Reserves a hole at the top of the kernel virtual
1978 address space.
1979
7e96287d
VG
1980 reset_devices [KNL] Force drivers to reset the underlying device
1981 during initialization.
1982
a9913044
RD
1983 resume= [SWSUSP]
1984 Specify the partition device for software suspend
1da177e4 1985
ecbd0da1
RW
1986 resume_offset= [SWSUSP]
1987 Specify the offset from the beginning of the partition
1988 given by "resume=" at which the swap header is located,
1989 in <PAGE_SIZE> units (needed only for swap files).
1990 See Documentation/power/swsusp-and-swap-files.txt
1991
0a7b35cb
MN
1992 retain_initrd [RAM] Keep initrd memory after extraction
1993
1da177e4
LT
1994 rhash_entries= [KNL,NET]
1995 Set number of hash buckets for route cache
1996
1997 riscom8= [HW,SERIAL]
1998 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1999
2000 ro [KNL] Mount root device read-only on boot
2001
2002 root= [KNL] Root filesystem
2003
2004 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2005 mount the root filesystem
2006
2007 rootflags= [KNL] Set root filesystem mount option string
2008
2009 rootfstype= [KNL] Set root filesystem type
2010
cc1ed754
PO
2011 rootwait [KNL] Wait (indefinitely) for root device to show up.
2012 Useful for devices that are detected asynchronously
2013 (e.g. USB and MMC devices).
2014
20510f2f
JM
2015 root_plug.vendor_id=
2016 [ROOTPLUG] Override the default vendor ID
2017
2018 root_plug.product_id=
2019 [ROOTPLUG] Override the default product ID
2020
2021 root_plug.debug=
2022 [ROOTPLUG] Enable debugging output
2023
1da177e4
LT
2024 rw [KNL] Mount root device read-write on boot
2025
2026 S [KNL] Run init in single mode
2027
2028 sa1100ir [NET]
2029 See drivers/net/irda/sa1100_ir.c.
2030
1da177e4 2031 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 2032
1da177e4
LT
2033 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2034 Format: <io>[,<timeout>[,<isapnp>]]
2035
2036 scsi_debug_*= [SCSI]
2037 See drivers/scsi/scsi_debug.c.
2038
2039 scsi_default_dev_flags=
2040 [SCSI] SCSI default device flags
2041 Format: <integer>
2042
2043 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2044 Format: <vendor>:<model>:<flags>
2045 (flags are integer value)
2046
6af6632a
RD
2047 scsi_logging_level= [SCSI] a bit mask of logging levels
2048 See drivers/scsi/scsi_logging.h for bits. Also
2049 settable via sysctl at dev.scsi.logging_level
2050 (/proc/sys/dev/scsi/logging_level).
2051 There is also a nice 'scsi_logging_level' script in the
2052 S390-tools package, available for download at
2053 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 2054
3e082a91
MW
2055 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2056 discovered. async scans them in kernel threads,
2057 allowing boot to proceed. none ignores them, expecting
2058 user space to do the scan.
2059
0cb55ad2
RD
2060 security= [SECURITY] Choose a security module to enable at boot.
2061 If this boot parameter is not specified, only the first
2062 security module asking for security registration will be
2063 loaded. An invalid security module name will be treated
2064 as if no module has been chosen.
2065
2066 selinux= [SELINUX] Disable or enable SELinux at boot time.
1da177e4
LT
2067 Format: { "0" | "1" }
2068 See security/selinux/Kconfig help text.
2069 0 -- disable.
2070 1 -- enable.
2071 Default value is set via kernel config option.
2072 If enabled at boot time, /selinux/disable can be used
2073 later to disable prior to initial policy load.
2074
cd4f0ef7 2075 serialnumber [BUGS=X86-32]
1da177e4 2076
1da177e4
LT
2077 shapers= [NET]
2078 Maximal number of shapers.
a9913044 2079
b05f78f5
YL
2080 show_msr= [x86] show boot-time MSR settings
2081 Format: { <integer> }
2082 Show boot-time (BIOS-initialized) MSR settings.
2083 The parameter means the number of CPUs to show,
2084 for example 1 means boot CPU only.
2085
1da177e4
LT
2086 sim710= [SCSI,HW]
2087 See header of drivers/scsi/sim710.c.
2088
2089 simeth= [IA-64]
2090 simscsi=
a9913044 2091
1da177e4
LT
2092 slram= [HW,MTD]
2093
f0630fff
CL
2094 slub_debug[=options[,slabs]] [MM, SLUB]
2095 Enabling slub_debug allows one to determine the
2096 culprit if slab objects become corrupted. Enabling
2097 slub_debug can create guard zones around objects and
2098 may poison objects when not in use. Also tracks the
2099 last alloc / free. For more information see
2100 Documentation/vm/slub.txt.
c1aee215
CL
2101
2102 slub_max_order= [MM, SLUB]
f0630fff
CL
2103 Determines the maximum allowed order for slabs.
2104 A high setting may cause OOMs due to memory
2105 fragmentation. For more information see
2106 Documentation/vm/slub.txt.
c1aee215
CL
2107
2108 slub_min_objects= [MM, SLUB]
f0630fff
CL
2109 The minimum number of objects per slab. SLUB will
2110 increase the slab order up to slub_max_order to
2111 generate a sufficiently large slab able to contain
2112 the number of objects indicated. The higher the number
2113 of objects the smaller the overhead of tracking slabs
2114 and the less frequently locks need to be acquired.
c1aee215
CL
2115 For more information see Documentation/vm/slub.txt.
2116
2117 slub_min_order= [MM, SLUB]
2118 Determines the mininum page order for slabs. Must be
f0630fff 2119 lower than slub_max_order.
c1aee215
CL
2120 For more information see Documentation/vm/slub.txt.
2121
2122 slub_nomerge [MM, SLUB]
f0630fff 2123 Disable merging of slabs with similar size. May be
c1aee215 2124 necessary if there is some reason to distinguish
f0630fff
CL
2125 allocs to different slabs. Debug options disable
2126 merging on their own.
c1aee215
CL
2127 For more information see Documentation/vm/slub.txt.
2128
1da177e4
LT
2129 smart2= [HW]
2130 Format: <io1>[,<io2>[,...,<io8>]]
2131
cd4f0ef7 2132 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2133 attempt to substitute SMP alternatives once at boot.
2134
d0d4f69b
BH
2135 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2136 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2137 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2138 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2139 smsc-ircc2.ircc_irq= [HW] IRQ line
2140 smsc-ircc2.ircc_dma= [HW] DMA channel
2141 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2142 0: Toshiba Satellite 1800 (GP data pin select)
2143 1: Fast pin select (default)
2144 2: ATC IRMode
2145
1da177e4
LT
2146 snd-ad1816a= [HW,ALSA]
2147
2148 snd-ad1848= [HW,ALSA]
2149
2150 snd-ali5451= [HW,ALSA]
2151
2152 snd-als100= [HW,ALSA]
2153
2154 snd-als4000= [HW,ALSA]
2155
2156 snd-azt2320= [HW,ALSA]
2157
2158 snd-cmi8330= [HW,ALSA]
2159
2160 snd-cmipci= [HW,ALSA]
2161
2162 snd-cs4231= [HW,ALSA]
2163
2164 snd-cs4232= [HW,ALSA]
2165
2166 snd-cs4236= [HW,ALSA]
2167
2168 snd-cs4281= [HW,ALSA]
2169
2170 snd-cs46xx= [HW,ALSA]
2171
2172 snd-dt019x= [HW,ALSA]
2173
2174 snd-dummy= [HW,ALSA]
2175
2176 snd-emu10k1= [HW,ALSA]
2177
2178 snd-ens1370= [HW,ALSA]
2179
2180 snd-ens1371= [HW,ALSA]
2181
2182 snd-es968= [HW,ALSA]
2183
2184 snd-es1688= [HW,ALSA]
2185
2186 snd-es18xx= [HW,ALSA]
2187
2188 snd-es1938= [HW,ALSA]
2189
2190 snd-es1968= [HW,ALSA]
2191
2192 snd-fm801= [HW,ALSA]
2193
2194 snd-gusclassic= [HW,ALSA]
2195
2196 snd-gusextreme= [HW,ALSA]
2197
2198 snd-gusmax= [HW,ALSA]
2199
2200 snd-hdsp= [HW,ALSA]
2201
2202 snd-ice1712= [HW,ALSA]
2203
2204 snd-intel8x0= [HW,ALSA]
2205
2206 snd-interwave= [HW,ALSA]
2207
2208 snd-interwave-stb=
2209 [HW,ALSA]
2210
2211 snd-korg1212= [HW,ALSA]
2212
2213 snd-maestro3= [HW,ALSA]
2214
2215 snd-mpu401= [HW,ALSA]
2216
2217 snd-mtpav= [HW,ALSA]
2218
2219 snd-nm256= [HW,ALSA]
2220
2221 snd-opl3sa2= [HW,ALSA]
2222
2223 snd-opti92x-ad1848=
2224 [HW,ALSA]
2225
2226 snd-opti92x-cs4231=
2227 [HW,ALSA]
2228
2229 snd-opti93x= [HW,ALSA]
2230
2231 snd-pmac= [HW,ALSA]
2232
2233 snd-rme32= [HW,ALSA]
2234
2235 snd-rme96= [HW,ALSA]
2236
2237 snd-rme9652= [HW,ALSA]
2238
2239 snd-sb8= [HW,ALSA]
2240
2241 snd-sb16= [HW,ALSA]
2242
2243 snd-sbawe= [HW,ALSA]
2244
2245 snd-serial= [HW,ALSA]
2246
2247 snd-sgalaxy= [HW,ALSA]
2248
2249 snd-sonicvibes= [HW,ALSA]
2250
2251 snd-sun-amd7930=
2252 [HW,ALSA]
2253
2254 snd-sun-cs4231= [HW,ALSA]
2255
2256 snd-trident= [HW,ALSA]
2257
2258 snd-usb-audio= [HW,ALSA,USB]
2259
2260 snd-via82xx= [HW,ALSA]
2261
2262 snd-virmidi= [HW,ALSA]
2263
2264 snd-wavefront= [HW,ALSA]
2265
2266 snd-ymfpci= [HW,ALSA]
a9913044 2267
9c44bc03
IM
2268 softlockup_panic=
2269 [KNL] Should the soft-lockup detector generate panics.
2270
1da177e4
LT
2271 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2272 See Documentation/sonypi.txt
2273
2274 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2275 See Documentation/serial/specialix.txt.
1da177e4
LT
2276
2277 spia_io_base= [HW,MTD]
2278 spia_fio_base=
2279 spia_pedr=
2280 spia_peddr=
2281
2282 sscape= [HW,OSS]
2283 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2284
1da177e4
LT
2285 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2286 See Documentation/scsi/st.txt.
2287
f38f1d2a
SR
2288 stacktrace [FTRACE]
2289 Enabled the stack tracer on boot up.
2290
1da177e4
LT
2291 sti= [PARISC,HW]
2292 Format: <num>
2293 Set the STI (builtin display/keyboard on the HP-PARISC
2294 machines) console (graphic card) which should be used
2295 as the initial boot-console.
2296 See also comment in drivers/video/console/sticore.c.
2297
2298 sti_font= [HW]
2299 See comment in drivers/video/console/sticore.c.
2300
2301 stifb= [HW]
2302 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2303
42a7fc4a
GB
2304 sunrpc.pool_mode=
2305 [NFS]
2306 Control how the NFS server code allocates CPUs to
2307 service thread pools. Depending on how many NICs
2308 you have and where their interrupts are bound, this
2309 option will affect which CPUs will do NFS serving.
2310 Note: this parameter cannot be changed while the
2311 NFS server is running.
2312
2313 auto the server chooses an appropriate mode
2314 automatically using heuristics
2315 global a single global pool contains all CPUs
2316 percpu one pool for each CPU
2317 pernode one pool for each NUMA node (equivalent
2318 to global on non-NUMA machines)
2319
1da177e4 2320 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2321
1da177e4
LT
2322 switches= [HW,M68k]
2323
2324 sym53c416= [HW,SCSI]
2325 See header of drivers/scsi/sym53c416.c.
2326
5d6f647f
IM
2327 sysrq_always_enabled
2328 [KNL]
2329 Ignore sysrq setting - this boot parameter will
2330 neutralize any effect of /proc/sys/kernel/sysrq.
2331 Useful for debugging.
2332
1da177e4
LT
2333 t128= [HW,SCSI]
2334 See header of drivers/scsi/t128.c.
2335
2336 tdfx= [HW,DRM]
2337
77437fd4
DB
2338 test_suspend= [SUSPEND]
2339 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2340 standby suspend) as the system sleep state to briefly
2341 enter during system startup. The system is woken from
2342 this state using a wakeup-capable RTC alarm.
2343
1da177e4
LT
2344 thash_entries= [KNL,NET]
2345 Set number of hash buckets for TCP connection
2346
f8707ec9
LB
2347 thermal.act= [HW,ACPI]
2348 -1: disable all active trip points in all thermal zones
2349 <degrees C>: override all lowest active trip points
2350
c52a7419
LB
2351 thermal.crt= [HW,ACPI]
2352 -1: disable all critical trip points in all thermal zones
22a94d79 2353 <degrees C>: override all critical trip points
c52a7419 2354
f5487145
LB
2355 thermal.nocrt= [HW,ACPI]
2356 Set to disable actions on ACPI thermal zone
2357 critical and hot trip points.
2358
72b33ef8
LB
2359 thermal.off= [HW,ACPI]
2360 1: disable ACPI thermal control
2361
a70cdc52
LB
2362 thermal.psv= [HW,ACPI]
2363 -1: disable all passive trip points
ada9cfdd
RD
2364 <degrees C>: override all passive trip points to this
2365 value
a70cdc52 2366
730ff34d
LB
2367 thermal.tzp= [HW,ACPI]
2368 Specify global default ACPI thermal zone polling rate
2369 <deci-seconds>: poll all this frequency
2370 0: no polling (default)
2371
1da177e4
LT
2372 tmscsim= [HW,SCSI]
2373 See comment before function dc390_setup() in
2374 drivers/scsi/tmscsim.c.
2375
2b1a61f0
HC
2376 topology= [S390]
2377 Format: {off | on}
2378 Specify if the kernel should make use of the cpu
2379 topology informations if the hardware supports these.
2380 The scheduler will make use of these informations and
2381 e.g. base its process migration decisions on it.
2382 Default is off.
2383
1da177e4
LT
2384 tp720= [HW,PS2]
2385
631595fb
KM
2386 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2387
1da177e4 2388 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2389 Format:
2390 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2391
395628ef
AK
2392 tsc= Disable clocksource-must-verify flag for TSC.
2393 Format: <string>
2394 [x86] reliable: mark tsc clocksource as reliable, this
2395 disables clocksource verification at runtime.
2396 Used to enable high-resolution timer mode on older
2397 hardware, and in virtualized environment.
2398
a9913044
RD
2399 turbografx.map[2|3]= [HW,JOY]
2400 TurboGraFX parallel port interface
2401 Format:
2402 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2403 See also Documentation/input/joystick-parport.txt
2404
2405 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2406 See header of drivers/scsi/u14-34f.c.
2407
2408 uart401= [HW,OSS]
2409 Format: <io>,<irq>
2410
2411 uart6850= [HW,OSS]
2412 Format: <io>,<irq>
2413
5f8364b7
AS
2414 uhci-hcd.ignore_oc=
2415 [USB] Ignore overcurrent events (default N).
2416 Some badly-designed motherboards generate lots of
2417 bogus events, for ports that aren't wired to
2418 anything. Set this parameter to avoid log spamming.
2419 Note that genuine overcurrent events won't be
2420 reported either.
2421
e3a61b0a 2422 unknown_nmi_panic
6cececfc 2423 [X86]
e3a61b0a
SA
2424 Set unknown_nmi_panic=1 early on boot.
2425
b5e795f8
AS
2426 usbcore.autosuspend=
2427 [USB] The autosuspend time delay (in seconds) used
2428 for newly-detected USB devices (default 2). This
2429 is the time required before an idle device will be
2430 autosuspended. Devices for which the delay is set
eaafbc3a 2431 to a negative value won't be autosuspended at all.
b5e795f8 2432
fd7c519d
JK
2433 usbcore.usbfs_snoop=
2434 [USB] Set to log all usbfs traffic (default 0 = off).
2435
2436 usbcore.blinkenlights=
2437 [USB] Set to cycle leds on hubs (default 0 = off).
2438
2439 usbcore.old_scheme_first=
2440 [USB] Start with the old device initialization
2441 scheme (default 0 = off).
2442
2443 usbcore.use_both_schemes=
2444 [USB] Try the other device initialization scheme
2445 if the first one fails (default 1 = enabled).
2446
2447 usbcore.initial_descriptor_timeout=
2448 [USB] Specifies timeout for the initial 64-byte
2449 USB_REQ_GET_DESCRIPTOR request in milliseconds
2450 (default 5000 = 5.0 seconds).
2451
1da177e4
LT
2452 usbhid.mousepoll=
2453 [USBHID] The interval which mice are to be polled at.
a9913044 2454
d4f373e5
AS
2455 usb-storage.delay_use=
2456 [UMS] The delay in seconds before a new device is
2457 scanned for Logical Units (default 5).
2458
2459 usb-storage.quirks=
2460 [UMS] A list of quirks entries to supplement or
2461 override the built-in unusual_devs list. List
2462 entries are separated by commas. Each entry has
2463 the form VID:PID:Flags where VID and PID are Vendor
2464 and Product ID values (4-digit hex numbers) and
2465 Flags is a set of characters, each corresponding
2466 to a common usb-storage quirk flag as follows:
c838ea46
AS
2467 a = SANE_SENSE (collect more than 18 bytes
2468 of sense data);
d4f373e5
AS
2469 c = FIX_CAPACITY (decrease the reported
2470 device capacity by one sector);
c838ea46
AS
2471 h = CAPACITY_HEURISTICS (decrease the
2472 reported device capacity by one
2473 sector if the number is odd);
d4f373e5
AS
2474 i = IGNORE_DEVICE (don't bind to this
2475 device);
2476 l = NOT_LOCKABLE (don't try to lock and
2477 unlock ejectable media);
2478 m = MAX_SECTORS_64 (don't transfer more
2479 than 64 sectors = 32 KB at a time);
c838ea46
AS
2480 o = CAPACITY_OK (accept the capacity
2481 reported by the device);
d4f373e5
AS
2482 r = IGNORE_RESIDUE (the device reports
2483 bogus residue values);
2484 s = SINGLE_LUN (the device has only one
2485 Logical Unit);
2486 w = NO_WP_DETECT (don't test whether the
2487 medium is write-protected).
2488 Example: quirks=0419:aaf5:rl,0421:0433:rc
2489
6cececfc 2490 vdso= [X86,SH]
1dbf527c 2491 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2492 vdso=1: enable VDSO (default)
2493 vdso=0: disable VDSO mapping
2494
6cececfc 2495 vdso32= [X86]
af65d648
RM
2496 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2497 vdso32=1: enable 32-bit VDSO (default)
2498 vdso32=0: disable 32-bit VDSO mapping
2499
d080d397
YI
2500 vector= [IA-64,SMP]
2501 vector=percpu: enable percpu vector domain
2502
1da177e4
LT
2503 video= [FB] Frame buffer configuration
2504 See Documentation/fb/modedb.txt.
2505
cd4f0ef7 2506 vga= [BOOT,X86-32] Select a particular video mode
954a8b81 2507 See Documentation/x86/boot.txt and
a9913044 2508 Documentation/svga.txt.
1da177e4
LT
2509 Use vga=ask for menu.
2510 This is actually a boot loader parameter; the value is
2511 passed to the kernel using a special protocol.
2512
a9913044 2513 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2514 size of <nn>. This can be used to increase the
2515 minimum size (128MB on x86). It can also be used to
2516 decrease the size and leave more room for directly
2517 mapped kernel RAM.
2518
585c3047
PO
2519 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2520 Format: <command>
1da177e4 2521
585c3047
PO
2522 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2523 Format: <command>
2524
2525 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2526 Format: <command>
a9913044 2527
0cb55ad2
RD
2528 vt.default_blu= [VT]
2529 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2530 Change the default blue palette of the console.
2531 This is a 16-member array composed of values
2532 ranging from 0-255.
2533
2534 vt.default_grn= [VT]
2535 Format: <green0>,<green1>,<green2>,...,<green15>
2536 Change the default green palette of the console.
2537 This is a 16-member array composed of values
2538 ranging from 0-255.
2539
2540 vt.default_red= [VT]
2541 Format: <red0>,<red1>,<red2>,...,<red15>
2542 Change the default red palette of the console.
2543 This is a 16-member array composed of values
2544 ranging from 0-255.
2545
2546 vt.default_utf8=
2547 [VT]
2548 Format=<0|1>
2549 Set system-wide default UTF-8 mode for all tty's.
2550 Default is 1, i.e. UTF-8 mode is enabled for all
2551 newly opened terminals.
2552
1da177e4
LT
2553 waveartist= [HW,OSS]
2554 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2555
1da177e4
LT
2556 wd33c93= [HW,SCSI]
2557 See header of drivers/scsi/wd33c93.c.
2558
2559 wd7000= [HW,SCSI]
2560 See header of drivers/scsi/wd7000.c.
2561
2562 wdt= [WDT] Watchdog
8dfe9c21 2563 See Documentation/watchdog/wdt.txt.
1da177e4 2564
0cb55ad2
RD
2565 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2566 default x2apic cluster mode on platforms
2567 supporting x2apic.
2568
1da177e4
LT
2569 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2570 xd_geo= See header of drivers/block/xd.c.
2571
2572 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2573 Format:
2574 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2575
a9913044 2576______________________________________________________________________
1da177e4
LT
2577
2578TODO:
2579
2580 Add documentation for ALSA options.
2581 Add more DRM drivers.