Merge branch 'ext3-latency-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git...
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / Documentation / kernel-parameters.txt
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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.
11ef697b 53 LIBATA Libata driver is enabled
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54 LP Printer support is enabled.
55 LOOP Loopback device support is enabled.
56 M68k M68k architecture is enabled.
57 These options have more detailed description inside of
58 Documentation/m68k/kernel-options.txt.
59 MCA MCA bus support is enabled.
60 MDA MDA console support is enabled.
61 MOUSE Appropriate mouse support is enabled.
309e57df 62 MSI Message Signaled Interrupts (PCI).
c8facbb6 63 MTD MTD (Memory Technology Device) support is enabled.
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64 NET Appropriate network support is enabled.
65 NUMA NUMA support is enabled.
734efb46 66 GENERIC_TIME The generic timeofday code is enabled.
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67 NFS Appropriate NFS support is enabled.
68 OSS OSS sound support is enabled.
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69 PV_OPS A paravirtualized kernel is enabled.
70 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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71 PARISC The PA-RISC architecture is enabled.
72 PCI PCI bus support is enabled.
7f785763 73 PCIE PCI Express support is enabled.
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74 PCMCIA The PCMCIA subsystem is enabled.
75 PNP Plug & Play support is enabled.
76 PPC PowerPC architecture is enabled.
77 PPT Parallel port support is enabled.
78 PS2 Appropriate PS/2 support is enabled.
79 RAM RAM disk support is enabled.
20510f2f 80 ROOTPLUG The example Root Plug LSM is enabled.
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81 S390 S390 architecture is enabled.
82 SCSI Appropriate SCSI support is enabled.
83 A lot of drivers has their options described inside of
84 Documentation/scsi/.
20510f2f 85 SECURITY Different security models are enabled.
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86 SELINUX SELinux support is enabled.
87 SERIAL Serial support is enabled.
e523d93c 88 SH SuperH architecture is enabled.
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89 SMP The kernel is an SMP kernel.
90 SPARC Sparc architecture is enabled.
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91 SWSUSP Software suspend (hibernation) is enabled.
92 SUSPEND System suspend states are enabled.
f38f1d2a 93 FTRACE Function tracing enabled.
1da177e4 94 TS Appropriate touchscreen support is enabled.
d4f373e5 95 UMS USB Mass Storage support is enabled.
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96 USB USB support is enabled.
97 USBHID USB Human Interface Device support is enabled.
98 V4L Video For Linux support is enabled.
99 VGA The VGA console has been enabled.
100 VT Virtual terminal support is enabled.
101 WDT Watchdog support is enabled.
102 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 103 X86-32 X86-32, aka i386 architecture is enabled.
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104 X86-64 X86-64 architecture is enabled.
105 More X86-64 boot options can be found in
71cced6e 106 Documentation/x86/x86_64/boot-options.txt .
c0115606 107 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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108
109In addition, the following text indicates that the option:
110
111 BUGS= Relates to possible processor bugs on the said processor.
112 KNL Is a kernel start-up parameter.
113 BOOT Is a boot loader parameter.
114
115Parameters denoted with BOOT are actually interpreted by the boot
116loader, and have no meaning to the kernel directly.
117Do not modify the syntax of boot loader parameters without extreme
954a8b81 118need or coordination with <Documentation/x86/boot.txt>.
1da177e4 119
5558870b 120There are also arch-specific kernel-parameters not documented here.
71cced6e 121See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 122
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123Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
124a trailing = on the name of any parameter states that that parameter will
125be entered as an environment variable, whereas its absence indicates that
126it will appear as a kernel argument readable via /proc/cmdline by programs
127running once the system is up.
128
9c4751fd 129The number of kernel parameters is not limited, but the length of the
130complete command line (parameters including spaces etc.) is limited to
131a fixed number of characters. This limit depends on the architecture
132and is between 256 and 4096 characters. It is defined in the file
133./include/asm/setup.h as COMMAND_LINE_SIZE.
134
135
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136 acpi= [HW,ACPI,X86-64,i386]
137 Advanced Configuration and Power Interface
af23f573 138 Format: { force | off | ht | strict | noirq | rsdt }
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139 force -- enable ACPI if default was off
140 off -- disable ACPI if default was on
141 noirq -- do not use ACPI for IRQ routing
142 ht -- run only enough ACPI to enable Hyper Threading
a9913044 143 strict -- Be less tolerant of platforms that are not
1da177e4 144 strictly ACPI specification compliant.
237889bf 145 rsdt -- prefer RSDT over (default) XSDT
1da177e4 146
53471121 147 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 148
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149 acpi_apic_instance= [ACPI, IOAPIC]
150 Format: <int>
151 2: use 2nd APIC table, if available
152 1,0: use 1st APIC table
4e381a4f 153 default: 0
a1fdcc0d 154
1da177e4 155 acpi_sleep= [HW,ACPI] Sleep options
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156 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
157 old_ordering, s4_nonvs }
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158 See Documentation/power/video.txt for information on
159 s3_bios and s3_mode.
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160 s3_beep is for debugging; it makes the PC's speaker beep
161 as soon as the kernel's real-mode entry point is called.
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162 s4_nohwsig prevents ACPI hardware signature from being
163 used during resume from hibernation.
d8f3de0d 164 old_ordering causes the ACPI 1.0 ordering of the _PTS
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165 control method, with respect to putting devices into
166 low power states, to be enforced (the ACPI 2.0 ordering
167 of _PTS is used by default).
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168 s4_nonvs prevents the kernel from saving/restoring the
169 ACPI NVS memory during hibernation.
a9913044 170
1da177e4 171 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 172 Format: { level | edge | high | low }
1da177e4 173
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174 acpi_irq_balance [HW,ACPI]
175 ACPI will balance active IRQs
176 default in APIC mode
1da177e4 177
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178 acpi_irq_nobalance [HW,ACPI]
179 ACPI will not move active IRQs (default)
180 default in PIC mode
1da177e4 181
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182 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
183 use by PCI
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184 Format: <irq>,<irq>...
185
a9913044 186 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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187 Format: <irq>,<irq>...
188
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189 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
190
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191 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
192 Format: To spoof as Windows 98: ="Microsoft Windows"
193
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194 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
195 acpi_osi="string1" # add string1 -- only one string
196 acpi_osi="!string2" # remove built-in string2
197 acpi_osi= # disable all strings
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198
199 acpi_serialize [HW,ACPI] force serialization of AML methods
200
201 acpi_skip_timer_override [HW,ACPI]
202 Recognize and ignore IRQ0/pin2 Interrupt Override.
203 For broken nForce2 BIOS resulting in XT-PIC timer.
ada9cfdd 204 acpi_use_timer_override [HW,ACPI]
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205 Use timer override. For some broken Nvidia NF5 boards
206 that require a timer override, but don't have
207 HPET
1da177e4 208
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209 acpi_backlight= [HW,ACPI]
210 acpi_backlight=vendor
211 acpi_backlight=video
212 If set to vendor, prefer vendor specific driver
213 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
214 of the ACPI video.ko driver.
215
216 acpi_display_output= [HW,ACPI]
217 acpi_display_output=vendor
218 acpi_display_output=video
219 See above.
220
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221 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
222 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 223 Format: <int>
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224 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
225 debug output. Bits in debug_layer correspond to a
226 _COMPONENT in an ACPI source file, e.g.,
227 #define _COMPONENT ACPI_PCI_COMPONENT
228 Bits in debug_level correspond to a level in
229 ACPI_DEBUG_PRINT statements, e.g.,
230 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
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231 The debug_level mask defaults to "info". See
232 Documentation/acpi/debug.txt for more information about
233 debug layers and levels.
a0d84a92 234
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235 Enable processor driver info messages:
236 acpi.debug_layer=0x20000000
237 Enable PCI/PCI interrupt routing info messages:
238 acpi.debug_layer=0x400000
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239 Enable AML "Debug" output, i.e., stores to the Debug
240 object while interpreting AML:
241 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
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242 Enable all messages related to ACPI hardware:
243 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
244
245 Some values produce so much output that the system is
246 unusable. The "log_buf_len" parameter may be useful
247 if you need to capture more output.
f989106c 248
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249 acpi.power_nocheck= [HW,ACPI]
250 Format: 1/0 enable/disable the check of power state.
251 On some bogus BIOS the _PSC object/_STA object of
252 power resource can't return the correct device power
253 state. In such case it is unneccessary to check its
254 power state again in power transition.
255 1 : disable the power state check
256
cd4f0ef7 257 acpi_pm_good [X86-32,X86-64]
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258 Override the pmtimer bug detection: force the kernel
259 to assume that this machine's pmtimer latches its value
260 and always returns good values.
261
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262 agp= [AGP]
263 { off | try_unsupported }
264 off: disable AGP support
265 try_unsupported: try to drive unsupported chipsets
266 (may crash computer or cause data corruption)
267
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268 enable_timer_pin_1 [i386,x86-64]
269 Enable PIN 1 of APIC timer
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270 Can be useful to work around chipset bugs
271 (in particular on some ATI chipsets).
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272 The kernel tries to set a reasonable default.
273
274 disable_timer_pin_1 [i386,x86-64]
275 Disable PIN 1 of APIC timer
276 Can be useful to work around chipset bugs.
277
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278 ad1848= [HW,OSS]
279 Format: <io>,<irq>,<dma>,<dma2>,<type>
280
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281 advansys= [HW,SCSI]
282 See header of drivers/scsi/advansys.c.
283
284 advwdt= [HW,WDT] Advantech WDT
285 Format: <iostart>,<iostop>
286
287 aedsp16= [HW,OSS] Audio Excel DSP 16
288 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
289 See also header of sound/oss/aedsp16.c.
a9913044 290
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291 aha152x= [HW,SCSI]
292 See Documentation/scsi/aha152x.txt.
293
294 aha1542= [HW,SCSI]
295 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
296
297 aic7xxx= [HW,SCSI]
298 See Documentation/scsi/aic7xxx.txt.
299
300 aic79xx= [HW,SCSI]
301 See Documentation/scsi/aic79xx.txt.
302
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303 amd_iommu= [HW,X86-84]
304 Pass parameters to the AMD IOMMU driver in the system.
305 Possible values are:
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306 isolate - enable device isolation (each device, as far
307 as possible, will get its own protection
3ce1f93c 308 domain) [default]
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309 share - put every device behind one IOMMU into the
310 same protection domain
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311 fullflush - enable flushing of IO/TLB entries when
312 they are unmapped. Otherwise they are
313 flushed before they will be reused, which
314 is a lot of faster
315
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316 amd_iommu_size= [HW,X86-64]
317 Define the size of the aperture for the AMD IOMMU
318 driver. Possible values are:
319 '32M', '64M' (default), '128M', '256M', '512M', '1G'
320
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321 amijoy.map= [HW,JOY] Amiga joystick support
322 Map of devices attached to JOY0DAT and JOY1DAT
323 Format: <a>,<b>
324 See also Documentation/kernel/input/joystick.txt
325
326 analog.map= [HW,JOY] Analog joystick and gamepad support
327 Specifies type or capabilities of an analog joystick
328 connected to one of 16 gameports
329 Format: <type1>,<type2>,..<type16>
330
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331 apc= [HW,SPARC]
332 Power management functions (SPARCstation-4/5 + deriv.)
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333 Format: noidle
334 Disable APC CPU standby support. SPARCstation-Fox does
335 not play well with APC CPU idle - disable it if you have
336 APC and your system crashes randomly.
337
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338 apic= [APIC,i386] Advanced Programmable Interrupt Controller
339 Change the output verbosity whilst booting
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340 Format: { quiet (default) | verbose | debug }
341 Change the amount of debugging information output
342 when initialising the APIC and IO-APIC components.
a9913044 343
1da177e4 344 apm= [APM] Advanced Power Management
71f77055 345 See header of arch/x86/kernel/apm_32.c.
1da177e4 346
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347 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
348 Format: <io>,<irq>,<nodeID>
349
350 ataflop= [HW,M68k]
351
352 atarimouse= [HW,MOUSE] Atari Mouse
353
354 atascsi= [HW,SCSI] Atari SCSI
355
356 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
357 EzKey and similar keyboards
358
359 atkbd.reset= [HW] Reset keyboard during initialization
360
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361 atkbd.set= [HW] Select keyboard code set
362 Format: <int> (2 = AT (default), 3 = PS/2)
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363
364 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
365 keyboards
366
367 atkbd.softraw= [HW] Choose between synthetic and real raw mode
368 Format: <bool> (0 = real, 1 = synthetic (default))
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369
370 atkbd.softrepeat= [HW]
371 Use software keyboard repeat
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372
373 autotest [IA64]
374
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375 baycom_epp= [HW,AX25]
376 Format: <io>,<mode>
a9913044 377
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378 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
379 Format: <io>,<mode>
380 See header of drivers/net/hamradio/baycom_par.c.
381
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382 baycom_ser_fdx= [HW,AX25]
383 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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384 Format: <io>,<irq>,<mode>[,<baud>]
385 See header of drivers/net/hamradio/baycom_ser_fdx.c.
386
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387 baycom_ser_hdx= [HW,AX25]
388 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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389 Format: <io>,<irq>,<mode>
390 See header of drivers/net/hamradio/baycom_ser_hdx.c.
391
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392 boot_delay= Milliseconds to delay each printk during boot.
393 Values larger than 10 seconds (10000) are changed to
394 no delay (0).
395 Format: integer
396
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397 bootmem_debug [KNL] Enable bootmem allocator debug messages.
398
1da177e4 399 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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400 bttv.radio= Most important insmod options are available as
401 kernel args too.
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402 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
403 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
404
405 BusLogic= [HW,SCSI]
406 See drivers/scsi/BusLogic.c, comment before function
407 BusLogic_ParseDriverOptions().
408
409 c101= [NET] Moxa C101 synchronous serial card
410
cd4f0ef7 411 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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412 Sometimes CPU hardware bugs make them report the cache
413 size incorrectly. The kernel will attempt work arounds
414 to fix known problems, but for some CPUs it is not
415 possible to determine what the correct size should be.
416 This option provides an override for these situations.
417
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418 security= [SECURITY] Choose a security module to enable at boot.
419 If this boot parameter is not specified, only the first
420 security module asking for security registration will be
421 loaded. An invalid security module name will be treated
422 as if no module has been chosen.
423
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424 capability.disable=
425 [SECURITY] Disable capabilities. This would normally
426 be used only if an alternative security model is to be
427 configured. Potentially dangerous and should only be
428 used if you are entirely sure of the consequences.
429
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430 ccw_timeout_log [S390]
431 See Documentation/s390/CommonIO for details.
1da177e4 432
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433 cgroup_disable= [KNL] Disable a particular controller
434 Format: {name of the controller(s) to disable}
435 {Currently supported controllers - "memory"}
436
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437 checkreqprot [SELINUX] Set initial checkreqprot flag value.
438 Format: { "0" | "1" }
439 See security/selinux/Kconfig help text.
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440 0 -- check protection applied by kernel (includes
441 any implied execute protection).
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442 1 -- check protection requested by application.
443 Default value is set via a kernel config option.
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444 Value can be changed at runtime via
445 /selinux/checkreqprot.
446
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447 cio_ignore= [S390]
448 See Documentation/s390/CommonIO for details.
449
cd4f0ef7 450 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 451 [Deprecated]
3f6dee9b 452 Forces specified clocksource (if available) to be used
734efb46 453 when calculating gettimeofday(). If specified
3f6dee9b 454 clocksource is not available, it defaults to PIT.
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455 Format: { pit | tsc | cyclone | pmtmr }
456
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457 clocksource= [GENERIC_TIME] Override the default clocksource
458 Format: <string>
459 Override the default clocksource and use the clocksource
460 with the name specified.
461 Some clocksource names to choose from, depending on
462 the platform:
463 [all] jiffies (this is the base, fallback clocksource)
464 [ACPI] acpi_pm
465 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
466 pxa_timer,timer3,32k_counter,timer0_1
467 [AVR32] avr32
cd4f0ef7 468 [X86-32] pit,hpet,tsc,vmi-timer;
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469 scx200_hrt on Geode; cyclone on IBM x440
470 [MIPS] MIPS
471 [PARISC] cr16
472 [S390] tod
473 [SH] SuperH
474 [SPARC64] tick
475 [X86-64] hpet,tsc
476
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477 clearcpuid=BITNUM [X86]
478 Disable CPUID feature X for the kernel. See
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479 arch/x86/include/asm/cpufeature.h for the valid bit
480 numbers. Note the Linux specific bits are not necessarily
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481 stable over kernel options, but the vendor specific
482 ones should be.
483 Also note that user programs calling CPUID directly
484 or using the feature without checking anything
485 will still see it. This just prevents it from
486 being used by the kernel or shown in /proc/cpuinfo.
487 Also note the kernel might malfunction if you disable
488 some critical bits.
489
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490 code_bytes [IA32/X86_64] How many bytes of object code to print
491 in an oops report.
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492 Range: 0 - 8192
493 Default: 64
494
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495 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support
496 this option disables the debugging code at boot.
497
498 dma_debug_entries=<number>
499 This option allows to tune the number of preallocated
500 entries for DMA-API debugging code. One entry is
501 required per DMA-API allocation. Use this if the
502 DMA-API debugging code disables itself because the
503 architectural default is too low.
504
b17530bd 505 hpet= [X86-32,HPET] option to control HPET usage
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AH
506 Format: { enable (default) | disable | force |
507 verbose }
b17530bd 508 disable: disable HPET and use PIT instead
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509 force: allow force enabled of undocumented chips (ICH4,
510 VIA, nVidia)
b98103a5 511 verbose: show contents of HPET registers during setup
1da177e4 512
1da177e4 513 com20020= [HW,NET] ARCnet - COM20020 chipset
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RD
514 Format:
515 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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LT
516
517 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
518 Format: <io>[,<irq>]
519
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520 com90xx= [HW,NET]
521 ARCnet - COM90xx chipset (memory-mapped buffers)
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LT
522 Format: <io>[,<irq>[,<memstart>]]
523
524 condev= [HW,S390] console device
525 conmode=
a9913044 526
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LT
527 console= [KNL] Output console device and options.
528
529 tty<n> Use the virtual console device <n>.
530
531 ttyS<n>[,options]
f1a1c2dc 532 ttyUSB0[,options]
1da177e4 533 Use the specified serial port. The options are of
f1a1c2dc
RD
534 the form "bbbbpnf", where "bbbb" is the baud rate,
535 "p" is parity ("n", "o", or "e"), "n" is number of
536 bits, and "f" is flow control ("r" for RTS or
537 omit it). Default is "9600n8".
538
539 See Documentation/serial-console.txt for more
540 information. See
541 Documentation/networking/netconsole.txt for an
542 alternative.
1da177e4 543
18a8bd94
YL
544 uart[8250],io,<addr>[,options]
545 uart[8250],mmio,<addr>[,options]
1da177e4
LT
546 Start an early, polled-mode console on the 8250/16550
547 UART at the specified I/O port or MMIO address,
548 switching to the matching ttyS device later. The
549 options are the same as for ttyS, above.
550
f7511d5f
ST
551 If the device connected to the port is not a TTY but a braille
552 device, prepend "brl," before the device type, for instance
553 console=brl,ttyS0
554 For now, only VisioBraille is supported.
555
18a8bd94
YL
556 earlycon= [KNL] Output early console device and options.
557 uart[8250],io,<addr>[,options]
558 uart[8250],mmio,<addr>[,options]
559 Start an early, polled-mode console on the 8250/16550
560 UART at the specified I/O port or MMIO address.
561 The options are the same as for ttyS, above.
562
8f4ce8c3
AS
563 no_console_suspend
564 [HW] Never suspend the console
565 Disable suspending of consoles during suspend and
566 hibernate operations. Once disabled, debugging
567 messages can reach various consoles while the rest
568 of the system is being put to sleep (ie, while
569 debugging driver suspend/resume hooks). This may
570 not work reliably with all consoles, but is known
571 to work with serial and VGA consoles.
572
4cb0e11b
HK
573 coredump_filter=
574 [KNL] Change the default value for
575 /proc/<pid>/coredump_filter.
576 See also Documentation/filesystems/proc.txt.
577
1da177e4 578 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
579 Format:
580 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 581
dc009d92
EB
582 crashkernel=nn[KMG]@ss[KMG]
583 [KNL] Reserve a chunk of physical memory to
584 hold a kernel to switch to with kexec on panic.
585
fb391599
BW
586 crashkernel=range1:size1[,range2:size2,...][@offset]
587 [KNL] Same as above, but depends on the memory
588 in the running system. The syntax of range is
589 start-[end] where start and end are both
590 a memory unit (amount[KMG]). See also
591 Documentation/kdump/kdump.txt for a example.
592
1da177e4
LT
593 cs89x0_dma= [HW,NET]
594 Format: <dma>
595
596 cs89x0_media= [HW,NET]
597 Format: { rj45 | aui | bnc }
a9913044 598
a9913044 599 dasd= [HW,NET]
1da177e4
LT
600 See header of drivers/s390/block/dasd_devmap.c.
601
602 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
603 (one device per port)
604 Format: <port#>,<type>
605 See also Documentation/input/joystick-parport.txt
606
607 debug [KNL] Enable kernel debugging (events log level).
608
cae2ed9a
IM
609 debug_locks_verbose=
610 [KNL] verbose self-tests
611 Format=<0|1>
612 Print debugging info while doing the locking API
613 self-tests.
614 We default to 0 (no extra messages), setting it to
615 1 will print _a lot_ more information - normally
616 only useful to kernel developers.
617
3ac7fe5a
TG
618 debug_objects [KNL] Enable object debugging
619
d3af01f1
TG
620 debugpat [X86] Enable PAT debugging
621
2d27a966 622 decnet.addr= [HW,NET]
1da177e4
LT
623 Format: <area>[,<node>]
624 See also Documentation/networking/decnet.txt.
625
ecb77fa9 626 vt.default_blu= [VT]
55ff9780
AD
627 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
628 Change the default blue palette of the console.
629 This is a 16-member array composed of values
630 ranging from 0-255.
631
ecb77fa9 632 vt.default_grn= [VT]
55ff9780
AD
633 Format: <green0>,<green1>,<green2>,...,<green15>
634 Change the default green palette of the console.
635 This is a 16-member array composed of values
636 ranging from 0-255.
637
ecb77fa9 638 vt.default_red= [VT]
55ff9780
AD
639 Format: <red0>,<red1>,<red2>,...,<red15>
640 Change the default red palette of the console.
641 This is a 16-member array composed of values
642 ranging from 0-255.
643
ecb77fa9
ST
644 vt.default_utf8=
645 [VT]
55ff9780
AD
646 Format=<0|1>
647 Set system-wide default UTF-8 mode for all tty's.
ecb77fa9
ST
648 Default is 1, i.e. UTF-8 mode is enabled for all
649 newly opened terminals.
55ff9780 650
1da177e4
LT
651 dhash_entries= [KNL]
652 Set number of hash buckets for dentry cache.
a9913044 653
1da177e4
LT
654 digi= [HW,SERIAL]
655 IO parameters + enable/disable command.
656
657 digiepca= [HW,SERIAL]
658 See drivers/char/README.epca and
31c00fc1 659 Documentation/serial/digiepca.txt.
1da177e4 660
95ffa243
YL
661 disable_mtrr_cleanup [X86]
662 enable_mtrr_cleanup [X86]
663 The kernel tries to adjust MTRR layout from continuous
664 to discrete, to make X server driver able to add WB
665 entry later. This parameter enables/disables that.
666
667 mtrr_chunk_size=nn[KMG] [X86]
668 used for mtrr cleanup. It is largest continous chunk
669 that could hold holes aka. UC entries.
670
671 mtrr_gran_size=nn[KMG] [X86]
12031a62
YL
672 Used for mtrr cleanup. It is granularity of mtrr block.
673 Default is 1.
674 Large value could prevent small alignment from
675 using up MTRRs.
676
677 mtrr_spare_reg_nr=n [X86]
678 Format: <integer>
679 Range: 0,7 : spare reg number
680 Default : 1
681 Used for mtrr cleanup. It is spare mtrr entries number.
682 Set to 2 or more if your graphical card needs more.
95ffa243 683
093af8d7 684 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
685 By default the kernel will trim any uncacheable
686 memory out of your available memory pool based on
687 MTRR settings. This parameter disables that behavior,
688 possibly causing your machine to run very slowly.
689
1da177e4
LT
690 dmasound= [HW,OSS] Sound subsystem buffers
691
692 dscc4.setup= [NET]
693
694 dtc3181e= [HW,SCSI]
695
0ae53640 696 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
1da177e4
LT
697 earlyprintk=vga
698 earlyprintk=serial[,ttySn[,baudrate]]
5c05917e 699 earlyprintk=dbgp
1da177e4 700
a9913044 701 Append ",keep" to not disable it when the real console
1da177e4
LT
702 takes over.
703
5c05917e 704 Only vga or serial or usb debug port at a time.
1da177e4
LT
705
706 Currently only ttyS0 and ttyS1 are supported.
707
708 Interaction with the standard serial driver is not
709 very good.
710
711 The VGA output is eventually overwritten by the real
712 console.
713
714 eata= [HW,SCSI]
715
1da177e4 716 edd= [EDD]
8c4dd606 717 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 718
1da177e4
LT
719 eisa_irq_edge= [PARISC,HW]
720 See header of drivers/parisc/eisa.c.
721
cd4f0ef7 722 elanfreq= [X86-32]
1da177e4 723 See comment before function elanfreq_setup() in
71f77055 724 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
725
726 elevator= [IOSCHED]
16ab3adf 727 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
728 See Documentation/block/as-iosched.txt and
729 Documentation/block/deadline-iosched.txt for details.
730
e515a0d6 731 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
a9913044 732 Specifies physical address of start of kernel core
aac04b32
VG
733 image elf header. Generally kexec loader will
734 pass this option to capture kernel.
735 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
736
737 enforcing [SELINUX] Set initial enforcing status.
738 Format: {"0" | "1"}
739 See security/selinux/Kconfig help text.
740 0 -- permissive (log only, no denials).
741 1 -- enforcing (deny and log).
742 Default value is 0.
743 Value can be changed at runtime via /selinux/enforce.
744
1da177e4
LT
745 ether= [HW,NET] Ethernet cards parameters
746 This option is obsoleted by the "netdev=" option, which
747 has equivalent usage. See its documentation for details.
748
749 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
750 Format: <io>[,<irq>]
751
de1ba09b
AM
752 failslab=
753 fail_page_alloc=
754 fail_make_request=[KNL]
755 General fault injection mechanism.
756 Format: <interval>,<probability>,<space>,<times>
757 See also /Documentation/fault-injection/.
758
1da177e4
LT
759 fd_mcs= [HW,SCSI]
760 See header of drivers/scsi/fd_mcs.c.
761
762 fdomain= [HW,SCSI]
763 See header of drivers/scsi/fdomain.c.
764
765 floppy= [HW]
31c00fc1 766 See Documentation/blockdev/floppy.txt.
1da177e4 767
f13ae30e
AC
768 force_pal_cache_flush
769 [IA-64] Avoid check_sal_cache_flush which may hang on
770 buggy SAL_CACHE_FLUSH implementations. Using this
771 parameter will force ia64_sal_cache_flush to call
772 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
773
d9e54076
PZ
774 ftrace=[tracer]
775 [ftrace] will set and start the specified tracer
776 as early as possible in order to facilitate early
777 boot debugging.
778
779 ftrace_dump_on_oops
780 [ftrace] will dump the trace buffers on oops.
781
1da177e4
LT
782 gamecon.map[2|3]=
783 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
784 support via parallel port (up to 5 devices per port)
785 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
786 See also Documentation/input/joystick-parport.txt
787
788 gamma= [HW,DRM]
789
aaf23042
YL
790 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
791 Format: off | on
792 default: on
793
1da177e4
LT
794 gdth= [HW,SCSI]
795 See header of drivers/scsi/gdth.c.
796
797 gpt [EFI] Forces disk with valid GPT signature but
798 invalid Protective MBR to be treated as GPT.
799
1da177e4
LT
800 gvp11= [HW,SCSI]
801
802 hashdist= [KNL,NUMA] Large hashes allocated during boot
803 are distributed across NUMA nodes. Defaults on
804 for IA-64, off otherwise.
a9913044 805 Format: 0 | 1 (for off | on)
1da177e4
LT
806
807 hcl= [IA-64] SGI's Hardware Graph compatibility layer
808
809 hd= [EIDE] (E)IDE hard drive subsystem geometry
810 Format: <cyl>,<head>,<sect>
811
1da177e4
LT
812 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
813 size of <nn>. This works even on boxes that have no
814 highmem otherwise. This also works to reduce highmem
815 size on bigger boxes.
816
54cdfdb4
TG
817 highres= [KNL] Enable/disable high resolution timer mode.
818 Valid parameters: "on", "off"
819 Default: "on"
820
1da177e4
LT
821 hisax= [HW,ISDN]
822 See Documentation/isdn/README.HiSax.
823
b4718e62
AK
824 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
825 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
826 On x86-64 and powerpc, this option can be specified
827 multiple times interleaved with hugepages= to reserve
828 huge pages of different sizes. Valid pages sizes on
829 x86-64 are 2M (when the CPU supports "pse") and 1G
830 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
831 Note that 1GB pages can only be allocated at boot time
832 using hugepages= and not freed afterwards.
e11bfbfc
NP
833 default_hugepagesz=
834 [same as hugepagesz=] The size of the default
835 HugeTLB page size. This is the size represented by
836 the legacy /proc/ hugepages APIs, used for SHM, and
837 default size when mounting hugetlbfs filesystems.
838 Defaults to the default architecture's huge page size
839 if not specified.
1da177e4 840
6902aa84
PM
841 hlt [BUGS=ARM,SH]
842
555d61d6
HB
843 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
844 terminal devices. Valid values: 0..8
431429ff
HB
845 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
846 If specified, z/VM IUCV HVC accepts connections
847 from listed z/VM user IDs only.
cef7125d 848
3a853fb9 849 i2c_bus= [HW] Override the default board specific I2C bus speed
7954763b
JN
850 or register an additional I2C bus that is not
851 registered from board initialization code.
3a853fb9
JN
852 Format:
853 <bus_id>,<clkrate>
854
36d95739 855 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 856 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
857 i8042.dumbkbd [HW] Pretend that controller can only read data from
858 keyboard and cannot control its state
1da177e4
LT
859 (Don't attempt to blink the leds)
860 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 861 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
862 i8042.noloop [HW] Disable the AUX Loopback command while probing
863 for the AUX port
1da177e4
LT
864 i8042.nomux [HW] Don't check presence of an active multiplexing
865 controller
866 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
867 controllers
868 i8042.panicblink=
869 [HW] Frequency with which keyboard LEDs should blink
870 when kernel panics (default is 0.5 sec)
871 i8042.reset [HW] Reset the controller during init and cleanup
872 i8042.unlock [HW] Unlock (ignore) the keylock
873
874 i810= [HW,DRM]
875
e70c9d5e
DT
876 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
877 indicates that the driver is running on unsupported
878 hardware.
1da177e4
LT
879 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
880 does not match list of supported models.
881 i8k.power_status
882 [HW] Report power status in /proc/i8k
883 (disabled by default)
884 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
885 capability is set.
886
887 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
888 See Documentation/mca.txt.
889
890 icn= [HW,ISDN]
891 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
892
0af80c04
DF
893 ide-core.nodma= [HW] (E)IDE subsystem
894 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
895 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
896 .chs .ignore_cable are additional options
1c10e938 897 See Documentation/ide/ide.txt.
1da177e4 898
1da177e4 899 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
1c10e938 900 See Documentation/ide/ide.txt.
1da177e4 901
f039b754 902 idle= [X86]
ada9cfdd
RD
903 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
904 Poll forces a polling idle loop that can slightly
905 improve the performance of waking up a idle CPU, but
906 will use a lot of power and make the system run hot.
907 Not recommended.
908 idle=mwait: On systems which support MONITOR/MWAIT but
909 the kernel chose to not use it because it doesn't save
910 as much power as a normal idle loop, use the
911 MONITOR/MWAIT idle loop anyways. Performance should be
912 the same as idle=poll.
913 idle=halt: Halt is forced to be used for CPU idle.
c1e3b377 914 In such case C2/C3 won't be used again.
ada9cfdd 915 idle=nomwait: Disable mwait for CPU C-states
a9913044 916
594765a7
DC
917 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
918 Claim all unknown PCI IDE storage controllers.
919
79290822
IM
920 ignore_loglevel [KNL]
921 Ignore loglevel setting - this will print /all/
922 kernel messages to the console. Useful for debugging.
923
1da177e4
LT
924 ihash_entries= [KNL]
925 Set number of hash buckets for inode cache.
926
3323eec9
MZ
927 ima_audit= [IMA]
928 Format: { "0" | "1" }
929 0 -- integrity auditing messages. (Default)
930 1 -- enable informational integrity auditing messages.
931
932 ima_hash= [IMA]
933 Formt: { "sha1" | "md5" }
934 default: "sha1"
935
1da177e4
LT
936 in2000= [HW,SCSI]
937 See header of drivers/scsi/in2000.c.
938
939 init= [KNL]
940 Format: <full_path>
941 Run specified binary instead of /sbin/init as init
942 process.
943
944 initcall_debug [KNL] Trace initcalls as they are executed. Useful
945 for working out where the kernel is dying during
946 startup.
947
948 initrd= [BOOT] Specify the location of the initial ramdisk
949
950 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
951 Format: <irq>
952
953 inttest= [IA64]
954
e8de1481
AV
955 iomem= Disable strict checking of access to MMIO memory
956 strict regions from userspace.
957 relaxed
958
b552da87
PM
959 iommu= [x86]
960 off
961 force
962 noforce
963 biomerge
964 panic
965 nopanic
966 merge
967 nomerge
968 forcesac
969 soft
970
971
ba395927 972 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
0cd5c3c8
KM
973 on
974 Enable intel iommu driver.
ba395927
KA
975 off
976 Disable intel iommu driver.
977 igfx_off [Default Off]
978 By default, gfx is mapped as normal device. If a gfx
979 device has a dedicated DMAR unit, the DMAR unit is
980 bypassed by not enabling DMAR with this option. In
981 this case, gfx device will use physical address for
982 DMA.
7d3b03ce
KA
983 forcedac [x86_64]
984 With this option iommu will not optimize to look
985 for io virtual address below 32 bit forcing dual
986 address cycle on pci bus for cards supporting greater
987 than 32 bit addressing. The default is to look
988 for translation below 32 bit and if not available
989 then look in the higher range.
5e0d2a6f 990 strict [Default Off]
991 With this option on every unmap_single operation will
992 result in a hardware IOTLB flush operation as opposed
993 to batching them for performance.
ba395927 994
b02aae9c 995 io_delay= [X86-32,X86-64] I/O delay method
6e7c4025
IM
996 0x80
997 Standard port 0x80 based delay
998 0xed
999 Alternate port 0xed based delay (needed on some systems)
b02aae9c 1000 udelay
6e7c4025
IM
1001 Simple two microseconds delay
1002 none
1003 No delay
b02aae9c 1004
1da177e4
LT
1005 io7= [HW] IO7 for Marvel based alpha systems
1006 See comment before marvel_specify_io7 in
1007 arch/alpha/kernel/core_marvel.c.
1008
1009 ip= [IP_PNP]
6ded55da 1010 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
1011
1012 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
1013 See comment before ip2_setup() in
1014 drivers/char/ip2/ip2base.c.
1da177e4
LT
1015
1016 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1017 See header of drivers/scsi/ips.c.
1018
72c4a13a
SH
1019 ports= [IP_VS_FTP] IPVS ftp helper module
1020 Default is 21.
1021 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1022 may be specified.
1023 Format: <port>,<port>....
1024
200803df
AC
1025 irqfixup [HW]
1026 When an interrupt is not handled search all handlers
1027 for it. Intended to get systems with badly broken
1028 firmware running.
1029
1030 irqpoll [HW]
1031 When an interrupt is not handled search all handlers
1032 for it. Also check all handlers each timer
1033 interrupt. Intended to get systems with badly broken
1034 firmware running.
1035
1da177e4 1036 isapnp= [ISAPNP]
a9913044 1037 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
1038
1039 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
1040 Format:
1041 <cpu number>,...,<cpu number>
1042 or
b225d44e
LZ
1043 <cpu number>-<cpu number>
1044 (must be a positive range in ascending order)
22f2e280
DF
1045 or a mixture
1046 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 1047
1da177e4
LT
1048 This option can be used to specify one or more CPUs
1049 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
1050 algorithms. You can move a process onto or off an
1051 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
1052 <cpu number> begins at 0 and the maximum value is
1053 "number of CPUs in system - 1".
1054
1055 This option is the preferred way to isolate CPUs. The
a9913044
RD
1056 alternative -- manually setting the CPU mask of all
1057 tasks in the system -- can cause problems and
1058 suboptimal load balancer performance.
1da177e4 1059
a9913044 1060 iucv= [HW,NET]
1da177e4
LT
1061
1062 js= [HW,JOY] Analog joystick
1063 See Documentation/input/joystick.txt.
1064
cd4f0ef7 1065 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
ed7ed365
MG
1066 specifies the amount of memory usable by the kernel
1067 for non-movable allocations. The requested amount is
1068 spread evenly throughout all nodes in the system. The
1069 remaining memory in each node is used for Movable
1070 pages. In the event, a node is too small to have both
1071 kernelcore and Movable pages, kernelcore pages will
1072 take priority and other nodes will have a larger number
1073 of kernelcore pages. The Movable zone is used for the
1074 allocation of pages that may be reclaimed or moved
1075 by the page migration subsystem. This means that
1076 HugeTLB pages may not be allocated from this zone.
1077 Note that allocations like PTEs-from-HighMem still
1078 use the HighMem zone if it exists, and the Normal
1079 zone if it does not.
1080
cd4f0ef7 1081 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
7e63efef
MG
1082 is similar to kernelcore except it specifies the
1083 amount of memory used for migratable allocations.
1084 If both kernelcore and movablecore is specified,
1085 then kernelcore will be at *least* the specified
1086 value but may be more. If movablecore on its own
1087 is specified, the administrator must be careful
1088 that the amount of memory usable for all allocations
1089 is not too small.
1090
1da177e4
LT
1091 keepinitrd [HW,ARM]
1092
cd4f0ef7 1093 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1da177e4
LT
1094 in oops dumps.
1095
6cdf6e06
JW
1096 kgdboc= [HW] kgdb over consoles.
1097 Requires a tty driver that supports console polling.
1098 (only serial suported for now)
1099 Format: <serial_device>[,baud]
1100
9bed90c6
FF
1101 kmac= [MIPS] korina ethernet MAC address.
1102 Configure the RouterBoard 532 series on-chip
1103 Ethernet adapter MAC address.
1104
1da177e4
LT
1105 l2cr= [PPC]
1106
a78bfbfc
RB
1107 l3cr= [PPC]
1108
cd4f0ef7 1109 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1110 disabled it.
1da177e4 1111
ada9cfdd
RD
1112 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1113 in C2 power state.
e585bef8 1114
fcb71f6f
FC
1115 libata.dma= [LIBATA] DMA control
1116 libata.dma=0 Disable all PATA and SATA DMA
1117 libata.dma=1 PATA and SATA Disk DMA only
1118 libata.dma=2 ATAPI (CDROM) DMA only
1119 libata.dma=4 Compact Flash DMA only
1120 Combinations also work, so libata.dma=3 enables DMA
1121 for disks and CDROMs, but not CFs.
1122
78e70c23
DJ
1123 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1124 when set.
1125 Format: <int>
1126
33267325
TH
1127 libata.force= [LIBATA] Force configurations. The format is comma
1128 separated list of "[ID:]VAL" where ID is
1129 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1130 matching port, link or device. Basically, it matches
1131 the ATA ID string printed on console by libata. If
1132 the whole ID part is omitted, the last PORT and DEVICE
1133 values are used. If ID hasn't been specified yet, the
1134 configuration applies to all ports, links and devices.
1135
1136 If only DEVICE is omitted, the parameter applies to
1137 the port and all links and devices behind it. DEVICE
1138 number of 0 either selects the first device or the
1139 first fan-out link behind PMP device. It does not
1140 select the host link. DEVICE number of 15 selects the
1141 host link and device attached to it.
1142
1143 The VAL specifies the configuration to force. As long
1144 as there's no ambiguity shortcut notation is allowed.
1145 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1146 The following configurations can be forced.
1147
1148 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1149 Any ID with matching PORT is used.
1150
1151 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1152
1153 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1154 udma[/][16,25,33,44,66,100,133] notation is also
1155 allowed.
1156
1157 * [no]ncq: Turn on or off NCQ.
1158
05944bdf
TH
1159 * nohrst, nosrst, norst: suppress hard, soft
1160 and both resets.
1161
33267325
TH
1162 If there are multiple matching configurations changing
1163 the same attribute, the last one is used.
1164
7c4be253
RD
1165 lmb=debug [KNL] Enable lmb debug messages.
1166
1da177e4 1167 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1168 See Documentation/blockdev/ramdisk.txt.
1da177e4 1169
a6b25b67
RD
1170 lockd.nlm_grace_period=P [NFS] Assign grace period.
1171 Format: <integer>
1da177e4 1172
a6b25b67
RD
1173 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1174 Format: <integer>
1175
1176 lockd.nlm_timeout=T [NFS] Assign timeout value.
1177 Format: <integer>
1178
1179 lockd.nlm_udpport=M [NFS] Assign UDP port.
1180 Format: <integer>
1da177e4
LT
1181
1182 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1183 Format: <irq>
1184
1185 loglevel= All Kernel Messages with a loglevel smaller than the
1186 console loglevel will be printed to the console. It can
1187 also be changed with klogd or other programs. The
1188 loglevels are defined as follows:
1189
1190 0 (KERN_EMERG) system is unusable
1191 1 (KERN_ALERT) action must be taken immediately
1192 2 (KERN_CRIT) critical conditions
1193 3 (KERN_ERR) error conditions
1194 4 (KERN_WARNING) warning conditions
1195 5 (KERN_NOTICE) normal but significant condition
1196 6 (KERN_INFO) informational
1197 7 (KERN_DEBUG) debug-level messages
1198
1199 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1200 Format: { n | nk | nM }
1201 n must be a power of two. The default size
1202 is set in the kernel config file.
1da177e4 1203
accaa24c
RD
1204 logo.nologo [FB] Disables display of the built-in Linux logo.
1205 This may be used to provide more screen space for
1206 kernel log messages and is useful when debugging
1207 kernel boot problems.
1208
1da177e4
LT
1209 lp=0 [LP] Specify parallel ports to use, e.g,
1210 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1211 lp=reset first parallel port). 'lp=0' disables the
1212 lp=auto printer driver. 'lp=reset' (which can be
1213 specified in addition to the ports) causes
1214 attached printers to be reset. Using
1215 lp=port1,port2,... specifies the parallel ports
1216 to associate lp devices with, starting with
1217 lp0. A port specification may be 'none' to skip
1218 that lp device, or a parport name such as
1219 'parport0'. Specifying 'lp=auto' instead of a
1220 port specification list means that device IDs
1221 from each port should be examined, to see if
1222 an IEEE 1284-compliant printer is attached; if
1223 so, the driver will manage that printer.
1224 See also header of drivers/char/lp.c.
1225
1226 lpj=n [KNL]
1227 Sets loops_per_jiffy to given constant, thus avoiding
1228 time-consuming boot-time autodetection (up to 250 ms per
1229 CPU). 0 enables autodetection (default). To determine
1230 the correct value for your kernel, boot with normal
1231 autodetection and see what value is printed. Note that
1232 on SMP systems the preset will be applied to all CPUs,
1233 which is likely to cause problems if your CPUs need
1234 significantly divergent settings. An incorrect value
1235 will cause delays in the kernel to be wrong, leading to
1236 unpredictable I/O errors and other breakage. Although
1237 unlikely, in the extreme case this might damage your
1238 hardware.
1239
1240 ltpc= [NET]
1241 Format: <io>,<irq>,<dma>
1242
a9913044
RD
1243 mac5380= [HW,SCSI] Format:
1244 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1245
a9913044
RD
1246 machvec= [IA64] Force the use of a particular machine-vector
1247 (machvec) in a generic kernel.
1248 Example: machvec=hpzx1_swiotlb
1da177e4 1249
a9913044 1250 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
1251 be mounted
1252 Format: <1-256>
1253
1254 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1255 should make use of. maxcpus=n : n >= 0 limits the
1256 kernel to using 'n' processors. n=0 is a special case,
1257 it is equivalent to "nosmp", which also disables
1258 the IO APIC.
1da177e4 1259
1c207f95
RD
1260 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1261 or equal to this physical address is ignored.
2b2c3750 1262
a9913044 1263 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1264 Should be between 1 and 2^32-1.
1265
1266 max_report_luns=
a9913044 1267 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1268 Should be between 1 and 16384.
1269
1da177e4
LT
1270 mcatest= [IA-64]
1271
cd4f0ef7 1272 mce [X86-32] Machine Check Exception
1da177e4 1273
71cced6e 1274 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1275
1da177e4
LT
1276 md= [HW] RAID subsystems devices and level
1277 See Documentation/md.txt.
a9913044 1278
1da177e4
LT
1279 mdacon= [MDA]
1280 Format: <first>,<last>
1281 Specifies range of consoles to be captured by the MDA.
a9913044 1282
1da177e4
LT
1283 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1284 Amount of memory to be used when the kernel is not able
1285 to see the whole system memory or for test.
cd4f0ef7 1286 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1287 address space collisions. Without memmap= PCI devices
1288 could be placed at addresses belonging to unused RAM.
1289
cd4f0ef7 1290 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1291 memory.
1292
6902aa84
PM
1293 memchunk=nn[KMG]
1294 [KNL,SH] Allow user to override the default size for
1295 per-device physically contiguous DMA buffers.
1296
cd4f0ef7 1297 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1da177e4
LT
1298 E820 memory map, as specified by the user.
1299 Such memmap=exactmap lines can be constructed based on
1300 BIOS output or other requirements. See the memmap=nn@ss
1301 option description.
1302
1303 memmap=nn[KMG]@ss[KMG]
1304 [KNL] Force usage of a specific region of memory
1305 Region of memory to be used, from ss to ss+nn.
1306
1307 memmap=nn[KMG]#ss[KMG]
1308 [KNL,ACPI] Mark specific memory as ACPI data.
1309 Region of memory to be used, from ss to ss+nn.
1310
1311 memmap=nn[KMG]$ss[KMG]
1312 [KNL,ACPI] Mark specific memory as reserved.
1313 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1314 Example: Exclude memory from 0x18690000-0x1869ffff
1315 memmap=64K$0x18690000
1316 or
1317 memmap=0x10000$0x18690000
1da177e4 1318
9f077871
JF
1319 memory_corruption_check=0/1 [X86]
1320 Some BIOSes seem to corrupt the first 64k of
1321 memory when doing things like suspend/resume.
1322 Setting this option will scan the memory
1323 looking for corruption. Enabling this will
1324 both detect corruption and prevent the kernel
1325 from using the memory being corrupted.
1326 However, its intended as a diagnostic tool; if
1327 repeatable BIOS-originated corruption always
1328 affects the same memory, you can use memmap=
1329 to prevent the kernel from using that memory.
1330
1331 memory_corruption_check_size=size [X86]
1332 By default it checks for corruption in the low
1333 64k, making this memory unavailable for normal
1334 use. Use this parameter to scan for
1335 corruption in more or less memory.
1336
1337 memory_corruption_check_period=seconds [X86]
1338 By default it checks for corruption every 60
1339 seconds. Use this parameter to check at some
1340 other rate. 0 disables periodic checking.
1341
caadbdce 1342 memtest= [KNL,X86] Enable memtest
c64df707 1343 Format: <integer>
c64df707 1344 default : 0 <disable>
9e5f6cf5
AH
1345 Specifies the number of memtest passes to be
1346 performed. Each pass selects another test
1347 pattern from a given set of patterns. Memtest
1348 fills the memory with this pattern, validates
1349 memory contents and reserves bad memory
1350 regions that are detected.
c64df707 1351
1da177e4
LT
1352 meye.*= [HW] Set MotionEye Camera parameters
1353 See Documentation/video4linux/meye.txt.
1354
8f36881b
AS
1355 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1356 Multi-Function General Purpose Timers on AMD Geode
1357 platforms.
1358
e6c4dc6c
WT
1359 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1360 the BIOS has incorrectly applied a workaround. TinyBIOS
1361 version 0.98 is known to be affected, 0.99 fixes the
1362 problem by letting the user disable the workaround.
1363
1da177e4
LT
1364 mga= [HW,DRM]
1365
1c207f95
RD
1366 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1367 physical address is ignored.
1368
6b74ab97
MG
1369 mminit_loglevel=
1370 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1371 parameter allows control of the logging verbosity for
1372 the additional memory initialisation checks. A value
1373 of 0 disables mminit logging and a level of 4 will
1374 log everything. Information is printed at KERN_DEBUG
1375 so loglevel=8 may also need to be specified.
1376
1da177e4
LT
1377 mousedev.tap_time=
1378 [MOUSE] Maximum time between finger touching and
1379 leaving touchpad surface for touch to be considered
1380 a tap and be reported as a left button click (for
1381 touchpads working in absolute mode only).
1382 Format: <msecs>
1383 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1384 reporting absolute coordinates, such as tablets
1385 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1386 reporting absolute coordinates, such as tablets
1387
1388 mpu401= [HW,OSS]
1389 Format: <io>,<irq>
1390
1391 MTD_Partition= [MTD]
1392 Format: <name>,<region-number>,<size>,<offset>
1393
a9913044
RD
1394 MTD_Region= [MTD] Format:
1395 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1396
1397 mtdparts= [MTD]
c8facbb6 1398 See drivers/mtd/cmdlinepart.c.
1da177e4 1399
9db829f4
BD
1400 mtdset= [ARM]
1401 ARM/S3C2412 JIVE boot control
1402
1403 See arch/arm/mach-s3c2412/mach-jive.c
1404
1da177e4 1405 mtouchusb.raw_coordinates=
a9913044
RD
1406 [HW] Make the MicroTouch USB driver use raw coordinates
1407 ('y', default) or cooked coordinates ('n')
1da177e4
LT
1408
1409 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1410
1411 NCR_D700= [HW,SCSI]
1412 See header of drivers/scsi/NCR_D700.c.
1413
1414 ncr5380= [HW,SCSI]
1415
1416 ncr53c400= [HW,SCSI]
1417
1418 ncr53c400a= [HW,SCSI]
1419
1420 ncr53c406a= [HW,SCSI]
1421
1422 ncr53c8xx= [HW,SCSI]
1423
1424 netdev= [NET] Network devices parameters
1425 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1426 Note that mem_start is often overloaded to mean
1427 something different and driver-specific.
a9913044
RD
1428 This usage is only documented in each driver source
1429 file if at all.
1430
58401572
KPO
1431 nf_conntrack.acct=
1432 [NETFILTER] Enable connection tracking flow accounting
1433 0 to disable accounting
1434 1 to enable accounting
1435 Default value depends on CONFIG_NF_CT_ACCT that is
1436 going to be removed in 2.6.29.
1437
1da177e4 1438 nfsaddrs= [NFS]
6ded55da 1439 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
1440
1441 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
6ded55da 1442 See Documentation/filesystems/nfsroot.txt.
1da177e4 1443
a72b4422
TM
1444 nfs.callback_tcpport=
1445 [NFS] set the TCP port on which the NFSv4 callback
1446 channel should listen.
1447
58df095b
TM
1448 nfs.idmap_cache_timeout=
1449 [NFS] set the maximum lifetime for idmapper cache
1450 entries.
1451
f43bf0be
TM
1452 nfs.enable_ino64=
1453 [NFS] enable 64-bit inode numbers.
1454 If zero, the NFS client will fake up a 32-bit inode
1455 number for the readdir() and stat() syscalls instead
1456 of returning the full 64-bit number.
1457 The default is to return 64-bit inode numbers.
1458
e7ba176b
HS
1459 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1460 when a NMI is triggered.
1461 Format: [state][,regs][,debounce][,die]
1462
5b9a0e14
CG
1463 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1464 Format: [panic,][num]
1465 Valid num: 0,1,2
1466 0 - turn nmi_watchdog off
1467 1 - use the IO-APIC timer for the NMI watchdog
1468 2 - use the local APIC for the NMI watchdog using
1469 a performance counter. Note: This will use one performance
1470 counter and the local APIC's performance vector.
1471 When panic is specified panic when an NMI watchdog timeout occurs.
1472 This is useful when you use a panic=... timeout and need the box
1473 quickly up again.
1474 Instead of 1 and 2 it is possible to use the following
1475 symbolic names: lapic and ioapic
1476 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1da177e4 1477
cd4f0ef7 1478 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1479 emulation library even if a 387 maths coprocessor
1480 is present.
1481
c1aee215
CL
1482 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1483 caches in the slab allocator. Saves per-node memory,
1484 but will impact performance.
3395ee05 1485
a9913044
RD
1486 noalign [KNL,ARM]
1487
1da177e4
LT
1488 noapic [SMP,APIC] Tells the kernel to not make use of any
1489 IOAPICs that may be present in the system.
1490
1da177e4
LT
1491 nobats [PPC] Do not use BATs for mapping kernel lowmem
1492 on "Classic" PPC cores.
1493
1494 nocache [ARM]
a9913044 1495
163ecdff
SN
1496 nodelayacct [KNL] Disable per-task delay accounting
1497
1da177e4
LT
1498 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1499
6902aa84
PM
1500 nodsp [SH] Disable hardware DSP at boot time.
1501
8b2cb7a8
HY
1502 noefi [X86-32,X86-64] Disable EFI runtime services support.
1503
1da177e4
LT
1504 noexec [IA-64]
1505
cd4f0ef7 1506 noexec [X86-32,X86-64]
f5a1b191 1507 On X86-32 available only on PAE configured kernels.
1da177e4 1508 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1509 noexec=off: disable non-executable mappings
1510
1511 noexec32 [X86-64]
1512 This affects only 32-bit executables.
1513 noexec32=on: enable non-executable mappings (default)
1514 read doesn't imply executable mappings
1515 noexec32=off: disable non-executable mappings
1516 read implies executable mappings
1da177e4 1517
6902aa84
PM
1518 nofpu [SH] Disable hardware FPU at boot time.
1519
cd4f0ef7 1520 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1521 register save and restore. The kernel will only save
1522 legacy floating-point registers on task switch.
1da177e4 1523
191679fd
AK
1524 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1525
01a24d2b
PZ
1526 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1527 wfi(ARM) instruction doesn't work correctly and not to
1528 use it. This is also useful when using JTAG debugger.
a9913044 1529
cd4f0ef7 1530 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1531 instruction doesn't work correctly and not to
1532 use it.
1533
1f29fae2
SH
1534 no_file_caps Tells the kernel not to honor file capabilities. The
1535 only way then for a file to be executed with privilege
1536 is to be setuid root or executed by root.
1537
1da177e4
LT
1538 nohalt [IA-64] Tells the kernel not to use the power saving
1539 function PAL_HALT_LIGHT when idle. This increases
1540 power-consumption. On the positive side, it reduces
1541 interrupt wake-up latency, which may improve performance
1542 in certain environments such as networked servers or
1543 real-time systems.
1544
79bf2bb3
TG
1545 nohz= [KNL] Boottime enable/disable dynamic ticks
1546 Valid arguments: on, off
1547 Default: on
1548
cd4f0ef7 1549 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1550 disable unhandled interrupt sources.
1551
cd4f0ef7 1552 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
8542b200
ZA
1553 broken timer IRQ sources.
1554
1da177e4
LT
1555 noisapnp [ISAPNP] Disables ISA PnP code.
1556
1557 noinitrd [RAM] Tells the kernel not to load any configured
1558 initial RAM disk.
1559
1560 nointroute [IA-64]
1561
0aa366f3
TL
1562 nojitter [IA64] Disables jitter checking for ITC timers.
1563
cd4f0ef7 1564 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1565
cd4f0ef7 1566 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1567
6e1cb38a
SS
1568 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1569
af9d1388
SS
1570 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1571 default x2apic cluster mode on platforms
1572 supporting x2apic.
1573
1da177e4
LT
1574 noltlbs [PPC] Do not use large page/tlb entries for kernel
1575 lowmem mapping on PPC40x.
1576
312f1f01
H
1577 nomca [IA-64] Disable machine check abort handling
1578
cd4f0ef7 1579 nomce [X86-32] Machine Check Exception
abe37e5a 1580
83d7384f
AS
1581 nomfgpt [X86-32] Disable Multi-Function General Purpose
1582 Timer usage (for AMD Geode machines).
1583
cd4f0ef7 1584 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1585
cd4f0ef7 1586 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1587 with UP alternatives
1588
1da177e4
LT
1589 noresidual [PPC] Don't use residual data on PReP machines.
1590
a9913044
RD
1591 noresume [SWSUSP] Disables resume and restores original swap
1592 space.
1593
1da177e4
LT
1594 no-scroll [VGA] Disables scrollback.
1595 This is required for the Braillex ib80-piezo Braille
1596 reader made by F.H. Papenmeier (Germany).
1597
1598 nosbagart [IA-64]
1599
cd4f0ef7 1600 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1601
61ec7567
LB
1602 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1603 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1604
97842216
DJ
1605 nosoftlockup [KNL] Disable the soft-lockup detector.
1606
c077719b
KH
1607 noswapaccount [KNL] Disable accounting of swap in memory resource
1608 controller. (See Documentation/controllers/memory.txt)
1609
1da177e4
LT
1610 nosync [HW,M68K] Disables sync negotiation for all devices.
1611
cd4f0ef7 1612 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1613
1614 nousb [USB] Disable the USB subsystem
1615
1616 nowb [ARM]
a9913044 1617
a6c75b86
FY
1618 nptcg= [IA64] Override max number of concurrent global TLB
1619 purges which is reported from either PAL_VM_SUMMARY or
1620 SAL PALO.
1621
f0c0b2b8
KH
1622 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1623 one of ['zone', 'node', 'default'] can be specified
1624 This can be set from sysctl after boot.
1625 See Documentation/sysctl/vm.txt for details.
1626
a61c2d78
DJ
1627 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1628
7c4be253
RD
1629 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1630 See Documentation/debugging-via-ohci1394.txt for more
1631 info.
1632
3ef0e1f8
AS
1633 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1634 Rather than timing out after 20 ms if an EC
1635 command is not properly ACKed, override the length
1636 of the timeout. We have interrupts disabled while
1637 waiting for the ACK, so if this is set too high
1638 interrupts *may* be lost!
1639
1da177e4
LT
1640 opl3= [HW,OSS]
1641 Format: <io>
1642
1da177e4
LT
1643 oprofile.timer= [HW]
1644 Use timer interrupt instead of performance counters
1645
1da177e4
LT
1646 osst= [HW,SCSI] SCSI Tape Driver
1647 Format: <buffer_size>,<write_threshold>
1648 See also Documentation/scsi/st.txt.
1649
1650 panic= [KNL] Kernel behaviour on panic
1651 Format: <timeout>
1652
1653 parkbd.port= [HW] Parallel port number the keyboard adapter is
1654 connected to, default is 0.
1655 Format: <parport#>
1656 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1657 0 for XT, 1 for AT (default is AT).
a9913044
RD
1658 Format: <mode>
1659
1660 parport= [HW,PPT] Specify parallel ports. 0 disables.
1661 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1662 Use 'auto' to force the driver to use any
1663 IRQ/DMA settings detected (the default is to
1664 ignore detected IRQ/DMA settings because of
1665 possible conflicts). You can specify the base
1666 address, IRQ, and DMA settings; IRQ and DMA
1667 should be numbers, or 'auto' (for using detected
1668 settings on that particular port), or 'nofifo'
1669 (to avoid using a FIFO even if it is detected).
1670 Parallel ports are assigned in the order they
1671 are specified on the command line, starting
1672 with parport0.
1673
1674 parport_init_mode= [HW,PPT]
1675 Configure VIA parallel port to operate in
1676 a specific mode. This is necessary on Pegasos
1677 computer where firmware has no options for setting
1678 up parallel port mode and sets it to spp.
1679 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1680 Format: [spp|ps2|epp|ecp|ecpepp]
1681
a9913044
RD
1682 pas2= [HW,OSS] Format:
1683 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1684
1da177e4
LT
1685 pas16= [HW,SCSI]
1686 See header of drivers/scsi/pas16.c.
1687
dd287796
AM
1688 pause_on_oops=
1689 Halt all CPUs after the first oops has been printed for
1690 the specified number of seconds. This is to be used if
1691 your oopses keep scrolling off the screen.
1692
1da177e4
LT
1693 pcbit= [HW,ISDN]
1694
1695 pcd. [PARIDE]
1696 See header of drivers/block/paride/pcd.c.
31c00fc1 1697 See also Documentation/blockdev/paride.txt.
1da177e4 1698
a9913044 1699 pci=option[,option...] [PCI] various PCI subsystem options:
1cc0ca26
BH
1700 earlydump [X86] dump PCI config space before the kernel
1701 changes anything
c0115606 1702 off [X86] don't probe for the PCI bus
cd4f0ef7 1703 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1704 the hardware directly. Use this if your machine
1705 has a non-standard PCI host bridge.
cd4f0ef7 1706 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1707 hardware access methods are allowed. Use this
1708 if you experience crashes upon bootup and you
1709 suspect they are caused by the BIOS.
c0115606 1710 conf1 [X86] Force use of PCI Configuration
a9913044 1711 Mechanism 1.
c0115606 1712 conf2 [X86] Force use of PCI Configuration
a9913044 1713 Mechanism 2.
7f785763
RD
1714 noaer [PCIE] If the PCIEAER kernel config parameter is
1715 enabled, this kernel boot option can be used to
1716 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1717 nodomains [PCI] Disable support for multiple PCI
1718 root domains (aka PCI segments, in ACPI-speak).
cd4f0ef7 1719 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
61be6d66 1720 Configuration
309e57df
MW
1721 nomsi [MSI] If the PCI_MSI kernel config parameter is
1722 enabled, this kernel boot option can be used to
1723 disable the use of MSI interrupts system-wide.
a9322f64
SA
1724 noioapicquirk [APIC] Disable all boot interrupt quirks.
1725 Safety option to keep boot IRQs enabled. This
1726 should never be necessary.
9197979b
SA
1727 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1728 primary IO-APIC for bridges that cannot disable
1729 boot IRQs. This fixes a source of spurious IRQs
1730 when the system masks IRQs.
41b9eb26
SA
1731 noioapicreroute [APIC] Disable workaround that uses the
1732 boot IRQ equivalent of an IRQ that connects to
1733 a chipset where boot IRQs cannot be disabled.
1734 The opposite of ioapicreroute.
cd4f0ef7 1735 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1736 routing table. These calls are known to be buggy
1737 on several machines and they hang the machine
1738 when used, but on other computers it's the only
1739 way to get the interrupt routing table. Try
1740 this option if the kernel is unable to allocate
1741 IRQs or discover secondary PCI buses on your
1742 motherboard.
c0115606 1743 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1744 Use with caution as certain devices share
1745 address decoders between ROMs and other
1746 resources.
c0115606 1747 norom [X86] Do not assign address space to
bb71ad88
GH
1748 expansion ROMs that do not already have
1749 BIOS assigned address ranges.
c0115606 1750 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1751 assigned automatically to PCI devices. You can
1752 make the kernel exclude IRQs of your ISA cards
1753 this way.
c0115606 1754 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1755 of the PIRQ table (normally generated
1756 by the BIOS) if it is outside the
1757 F0000h-100000h range.
c0115606 1758 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1759 useful if the kernel is unable to find your
1760 secondary buses and you want to tell it
1761 explicitly which ones they are.
c0115606 1762 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1763 numbers ourselves, overriding
1764 whatever the firmware may have done.
c0115606 1765 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1766 in the BIOS $PIR table. This is needed on
1767 some systems with broken BIOSes, notably
1768 some HP Pavilion N5400 and Omnibook XE3
1769 notebooks. This will have no effect if ACPI
1770 IRQ routing is enabled.
c0115606 1771 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1772 or for PCI scanning.
c0115606 1773 use_crs [X86] Use _CRS for PCI resource
62f420f8 1774 allocation.
a9913044
RD
1775 routeirq Do IRQ routing for all PCI devices.
1776 This is normally done in pci_enable_device(),
1777 so this option is a temporary workaround
1778 for broken drivers that don't call it.
13a6ddb0
YL
1779 skip_isa_align [X86] do not align io start addr, so can
1780 handle more pci cards
a9913044
RD
1781 firmware [ARM] Do not re-enumerate the bus but instead
1782 just use the configuration from the
1783 bootloader. This is currently used on
1784 IXP2000 systems where the bus has to be
1785 configured a certain way for adjunct CPUs.
0637a70a
AK
1786 noearly [X86] Don't do any early type 1 scanning.
1787 This might help on some broken boards which
1788 machine check when some devices' config space
1789 is read. But various workarounds are disabled
1790 and some IOMMU drivers will not work.
6b4b78fe
MD
1791 bfsort Sort PCI devices into breadth-first order.
1792 This sorting is done to get a device
1793 order compatible with older (<= 2.4) kernels.
1794 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1795 cbiosize=nn[KMG] The fixed amount of bus space which is
1796 reserved for the CardBus bridge's IO window.
1797 The default value is 256 bytes.
1798 cbmemsize=nn[KMG] The fixed amount of bus space which is
1799 reserved for the CardBus bridge's memory
1800 window. The default value is 64 megabytes.
32a9a682
YS
1801 resource_alignment=
1802 Format:
1803 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1804 Specifies alignment and device to reassign
1805 aligned memory resources.
1806 If <order of align> is not specified,
1807 PAGE_SIZE is used as alignment.
1808 PCI-PCI bridge can be specified, if resource
1809 windows need to be expanded.
6b4b78fe 1810
e5665a45
CE
1811 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1812 Management.
1813 off Disable ASPM.
1814 force Enable ASPM even on devices that claim not to support it.
1815 WARNING: Forcing ASPM on may cause system lockups.
1816
1da177e4
LT
1817 pcmv= [HW,PCMCIA] BadgePAD 4
1818
1819 pd. [PARIDE]
31c00fc1 1820 See Documentation/blockdev/paride.txt.
1da177e4
LT
1821
1822 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1823 boot time.
1824 Format: { 0 | 1 }
1825 See arch/parisc/kernel/pdc_chassis.c
1826
1827 pf. [PARIDE]
31c00fc1 1828 See Documentation/blockdev/paride.txt.
1da177e4
LT
1829
1830 pg. [PARIDE]
31c00fc1 1831 See Documentation/blockdev/paride.txt.
1da177e4
LT
1832
1833 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 1834 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
1835
1836 plip= [PPT,NET] Parallel port network link
1837 Format: { parport<nr> | timid | 0 }
1838 See also Documentation/parport.txt.
1839
de32a243
TG
1840 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1841 Override pmtimer IOPort with a hex value.
1842 e.g. pmtmr=0x508
1843
97ef062b
BH
1844 pnp.debug [PNP]
1845 Enable PNP debug messages. This depends on the
1846 CONFIG_PNP_DEBUG_MESSAGES option.
1847
1da177e4
LT
1848 pnpacpi= [ACPI]
1849 { off }
1850
1851 pnpbios= [ISAPNP]
1852 { on | off | curr | res | no-curr | no-res }
1853
1854 pnp_reserve_irq=
1855 [ISAPNP] Exclude IRQs for the autoconfiguration
1856
1857 pnp_reserve_dma=
1858 [ISAPNP] Exclude DMAs for the autoconfiguration
1859
1860 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1861 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1862
1863 pnp_reserve_mem=
a9913044
RD
1864 [ISAPNP] Exclude memory regions for the
1865 autoconfiguration.
1da177e4
LT
1866 Ranges are in pairs (memory base and size).
1867
45807a1d
IM
1868 print-fatal-signals=
1869 [KNL] debug: print fatal signals
1870 print-fatal-signals=1: print segfault info to
1871 the kernel console.
1872 default: off.
1873
e84845c4
RD
1874 printk.time= Show timing data prefixed to each printk message line
1875 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1876
1da177e4 1877 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1878 Format: [schedule,]<number>
1879 Param: "schedule" - profile schedule points.
1880 Param: <number> - step/bucket size as a power of 2 for
1881 statistical time based profiling.
b3da2a73
MG
1882 Param: "sleep" - profile D-state sleeping (millisecs).
1883 Requires CONFIG_SCHEDSTATS
c0fe2e69 1884 Param: "kvm" - profile VM exits.
1da177e4 1885
a9913044 1886 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1887 Limit processor to maximum C-state
1888 max_cstate=9 overrides any DMI blacklist limit.
1889
41c0d868
LB
1890 processor.nocst [HW,ACPI]
1891 Ignore the _CST method to determine C-states,
1892 instead using the legacy FADT method
1893
1da177e4
LT
1894 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1895 before loading.
31c00fc1 1896 See Documentation/blockdev/ramdisk.txt.
1da177e4 1897
a9913044
RD
1898 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1899 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1900 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1901 per second.
a9913044
RD
1902 psmouse.resetafter= [HW,MOUSE]
1903 Try to reset the device after so many bad packets
1da177e4
LT
1904 (0 = never).
1905 psmouse.resolution=
1906 [HW,MOUSE] Set desired mouse resolution, in dpi.
1907 psmouse.smartscroll=
a9913044 1908 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1909 0 = disabled, 1 = enabled (default).
1910
1911 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1912 Format:
1913 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1914
1915 pt. [PARIDE]
31c00fc1 1916 See Documentation/blockdev/paride.txt.
1da177e4 1917
dc8c8587
KS
1918 pty.legacy_count=
1919 [KNL] Number of legacy pty's. Overwrites compiled-in
1920 default number.
1921
7d2c502f 1922 quiet [KNL] Disable most log messages
a9913044 1923
1da177e4
LT
1924 r128= [HW,DRM]
1925
1926 raid= [HW,RAID]
1927 See Documentation/md.txt.
1928
a9913044 1929 ramdisk_blocksize= [RAM]
31c00fc1 1930 See Documentation/blockdev/ramdisk.txt.
a9913044 1931
1da177e4 1932 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 1933 See Documentation/blockdev/ramdisk.txt.
1da177e4 1934
24aaef8d
RD
1935 rcupdate.blimit= [KNL,BOOT]
1936 Set maximum number of finished RCU callbacks to process
1937 in one batch.
21a1ea9e 1938
24aaef8d
RD
1939 rcupdate.qhimark= [KNL,BOOT]
1940 Set threshold of queued
21a1ea9e
DS
1941 RCU callbacks over which batch limiting is disabled.
1942
24aaef8d
RD
1943 rcupdate.qlowmark= [KNL,BOOT]
1944 Set threshold of queued RCU callbacks below which
1945 batch limiting is re-enabled.
21a1ea9e 1946
ffdfc409
OJ
1947 rdinit= [KNL]
1948 Format: <full_path>
1949 Run specified binary instead of /init from the ramdisk,
1950 used for early userspace startup. See initrd.
1951
cd4f0ef7 1952 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1953 Format: <reboot_mode>[,<reboot_mode2>[,...]]
ecb08d81 1954 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 1955
46b6d94e
PJ
1956 relax_domain_level=
1957 [KNL, SMP] Set scheduler's default relax_domain_level.
1958 See Documentation/cpusets.txt.
1959
1da177e4
LT
1960 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1961
cd4f0ef7 1962 reservetop= [X86-32]
461a9aff
ZA
1963 Format: nn[KMG]
1964 Reserves a hole at the top of the kernel virtual
1965 address space.
1966
7e96287d
VG
1967 reset_devices [KNL] Force drivers to reset the underlying device
1968 during initialization.
1969
a9913044
RD
1970 resume= [SWSUSP]
1971 Specify the partition device for software suspend
1da177e4 1972
ecbd0da1
RW
1973 resume_offset= [SWSUSP]
1974 Specify the offset from the beginning of the partition
1975 given by "resume=" at which the swap header is located,
1976 in <PAGE_SIZE> units (needed only for swap files).
1977 See Documentation/power/swsusp-and-swap-files.txt
1978
0a7b35cb
MN
1979 retain_initrd [RAM] Keep initrd memory after extraction
1980
1da177e4
LT
1981 rhash_entries= [KNL,NET]
1982 Set number of hash buckets for route cache
1983
1984 riscom8= [HW,SERIAL]
1985 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1986
1987 ro [KNL] Mount root device read-only on boot
1988
1989 root= [KNL] Root filesystem
1990
1991 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1992 mount the root filesystem
1993
1994 rootflags= [KNL] Set root filesystem mount option string
1995
1996 rootfstype= [KNL] Set root filesystem type
1997
cc1ed754
PO
1998 rootwait [KNL] Wait (indefinitely) for root device to show up.
1999 Useful for devices that are detected asynchronously
2000 (e.g. USB and MMC devices).
2001
20510f2f
JM
2002 root_plug.vendor_id=
2003 [ROOTPLUG] Override the default vendor ID
2004
2005 root_plug.product_id=
2006 [ROOTPLUG] Override the default product ID
2007
2008 root_plug.debug=
2009 [ROOTPLUG] Enable debugging output
2010
1da177e4
LT
2011 rw [KNL] Mount root device read-write on boot
2012
2013 S [KNL] Run init in single mode
2014
2015 sa1100ir [NET]
2016 See drivers/net/irda/sa1100_ir.c.
2017
1da177e4 2018 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 2019
1da177e4
LT
2020 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2021 Format: <io>[,<timeout>[,<isapnp>]]
2022
2023 scsi_debug_*= [SCSI]
2024 See drivers/scsi/scsi_debug.c.
2025
2026 scsi_default_dev_flags=
2027 [SCSI] SCSI default device flags
2028 Format: <integer>
2029
2030 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2031 Format: <vendor>:<model>:<flags>
2032 (flags are integer value)
2033
6af6632a
RD
2034 scsi_logging_level= [SCSI] a bit mask of logging levels
2035 See drivers/scsi/scsi_logging.h for bits. Also
2036 settable via sysctl at dev.scsi.logging_level
2037 (/proc/sys/dev/scsi/logging_level).
2038 There is also a nice 'scsi_logging_level' script in the
2039 S390-tools package, available for download at
2040 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 2041
3e082a91
MW
2042 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2043 discovered. async scans them in kernel threads,
2044 allowing boot to proceed. none ignores them, expecting
2045 user space to do the scan.
2046
1da177e4
LT
2047 selinux [SELINUX] Disable or enable SELinux at boot time.
2048 Format: { "0" | "1" }
2049 See security/selinux/Kconfig help text.
2050 0 -- disable.
2051 1 -- enable.
2052 Default value is set via kernel config option.
2053 If enabled at boot time, /selinux/disable can be used
2054 later to disable prior to initial policy load.
2055
cd4f0ef7 2056 serialnumber [BUGS=X86-32]
1da177e4 2057
1da177e4
LT
2058 shapers= [NET]
2059 Maximal number of shapers.
a9913044 2060
b05f78f5
YL
2061 show_msr= [x86] show boot-time MSR settings
2062 Format: { <integer> }
2063 Show boot-time (BIOS-initialized) MSR settings.
2064 The parameter means the number of CPUs to show,
2065 for example 1 means boot CPU only.
2066
1da177e4
LT
2067 sim710= [SCSI,HW]
2068 See header of drivers/scsi/sim710.c.
2069
2070 simeth= [IA-64]
2071 simscsi=
a9913044 2072
1da177e4
LT
2073 slram= [HW,MTD]
2074
f0630fff
CL
2075 slub_debug[=options[,slabs]] [MM, SLUB]
2076 Enabling slub_debug allows one to determine the
2077 culprit if slab objects become corrupted. Enabling
2078 slub_debug can create guard zones around objects and
2079 may poison objects when not in use. Also tracks the
2080 last alloc / free. For more information see
2081 Documentation/vm/slub.txt.
c1aee215
CL
2082
2083 slub_max_order= [MM, SLUB]
f0630fff
CL
2084 Determines the maximum allowed order for slabs.
2085 A high setting may cause OOMs due to memory
2086 fragmentation. For more information see
2087 Documentation/vm/slub.txt.
c1aee215
CL
2088
2089 slub_min_objects= [MM, SLUB]
f0630fff
CL
2090 The minimum number of objects per slab. SLUB will
2091 increase the slab order up to slub_max_order to
2092 generate a sufficiently large slab able to contain
2093 the number of objects indicated. The higher the number
2094 of objects the smaller the overhead of tracking slabs
2095 and the less frequently locks need to be acquired.
c1aee215
CL
2096 For more information see Documentation/vm/slub.txt.
2097
2098 slub_min_order= [MM, SLUB]
2099 Determines the mininum page order for slabs. Must be
f0630fff 2100 lower than slub_max_order.
c1aee215
CL
2101 For more information see Documentation/vm/slub.txt.
2102
2103 slub_nomerge [MM, SLUB]
f0630fff 2104 Disable merging of slabs with similar size. May be
c1aee215 2105 necessary if there is some reason to distinguish
f0630fff
CL
2106 allocs to different slabs. Debug options disable
2107 merging on their own.
c1aee215
CL
2108 For more information see Documentation/vm/slub.txt.
2109
1da177e4
LT
2110 smart2= [HW]
2111 Format: <io1>[,<io2>[,...,<io8>]]
2112
cd4f0ef7 2113 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2114 attempt to substitute SMP alternatives once at boot.
2115
d0d4f69b
BH
2116 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2117 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2118 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2119 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2120 smsc-ircc2.ircc_irq= [HW] IRQ line
2121 smsc-ircc2.ircc_dma= [HW] DMA channel
2122 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2123 0: Toshiba Satellite 1800 (GP data pin select)
2124 1: Fast pin select (default)
2125 2: ATC IRMode
2126
1da177e4
LT
2127 snd-ad1816a= [HW,ALSA]
2128
2129 snd-ad1848= [HW,ALSA]
2130
2131 snd-ali5451= [HW,ALSA]
2132
2133 snd-als100= [HW,ALSA]
2134
2135 snd-als4000= [HW,ALSA]
2136
2137 snd-azt2320= [HW,ALSA]
2138
2139 snd-cmi8330= [HW,ALSA]
2140
2141 snd-cmipci= [HW,ALSA]
2142
2143 snd-cs4231= [HW,ALSA]
2144
2145 snd-cs4232= [HW,ALSA]
2146
2147 snd-cs4236= [HW,ALSA]
2148
2149 snd-cs4281= [HW,ALSA]
2150
2151 snd-cs46xx= [HW,ALSA]
2152
2153 snd-dt019x= [HW,ALSA]
2154
2155 snd-dummy= [HW,ALSA]
2156
2157 snd-emu10k1= [HW,ALSA]
2158
2159 snd-ens1370= [HW,ALSA]
2160
2161 snd-ens1371= [HW,ALSA]
2162
2163 snd-es968= [HW,ALSA]
2164
2165 snd-es1688= [HW,ALSA]
2166
2167 snd-es18xx= [HW,ALSA]
2168
2169 snd-es1938= [HW,ALSA]
2170
2171 snd-es1968= [HW,ALSA]
2172
2173 snd-fm801= [HW,ALSA]
2174
2175 snd-gusclassic= [HW,ALSA]
2176
2177 snd-gusextreme= [HW,ALSA]
2178
2179 snd-gusmax= [HW,ALSA]
2180
2181 snd-hdsp= [HW,ALSA]
2182
2183 snd-ice1712= [HW,ALSA]
2184
2185 snd-intel8x0= [HW,ALSA]
2186
2187 snd-interwave= [HW,ALSA]
2188
2189 snd-interwave-stb=
2190 [HW,ALSA]
2191
2192 snd-korg1212= [HW,ALSA]
2193
2194 snd-maestro3= [HW,ALSA]
2195
2196 snd-mpu401= [HW,ALSA]
2197
2198 snd-mtpav= [HW,ALSA]
2199
2200 snd-nm256= [HW,ALSA]
2201
2202 snd-opl3sa2= [HW,ALSA]
2203
2204 snd-opti92x-ad1848=
2205 [HW,ALSA]
2206
2207 snd-opti92x-cs4231=
2208 [HW,ALSA]
2209
2210 snd-opti93x= [HW,ALSA]
2211
2212 snd-pmac= [HW,ALSA]
2213
2214 snd-rme32= [HW,ALSA]
2215
2216 snd-rme96= [HW,ALSA]
2217
2218 snd-rme9652= [HW,ALSA]
2219
2220 snd-sb8= [HW,ALSA]
2221
2222 snd-sb16= [HW,ALSA]
2223
2224 snd-sbawe= [HW,ALSA]
2225
2226 snd-serial= [HW,ALSA]
2227
2228 snd-sgalaxy= [HW,ALSA]
2229
2230 snd-sonicvibes= [HW,ALSA]
2231
2232 snd-sun-amd7930=
2233 [HW,ALSA]
2234
2235 snd-sun-cs4231= [HW,ALSA]
2236
2237 snd-trident= [HW,ALSA]
2238
2239 snd-usb-audio= [HW,ALSA,USB]
2240
2241 snd-via82xx= [HW,ALSA]
2242
2243 snd-virmidi= [HW,ALSA]
2244
2245 snd-wavefront= [HW,ALSA]
2246
2247 snd-ymfpci= [HW,ALSA]
a9913044 2248
9c44bc03
IM
2249 softlockup_panic=
2250 [KNL] Should the soft-lockup detector generate panics.
2251
1da177e4
LT
2252 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2253 See Documentation/sonypi.txt
2254
2255 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2256 See Documentation/serial/specialix.txt.
1da177e4
LT
2257
2258 spia_io_base= [HW,MTD]
2259 spia_fio_base=
2260 spia_pedr=
2261 spia_peddr=
2262
2263 sscape= [HW,OSS]
2264 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2265
1da177e4
LT
2266 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2267 See Documentation/scsi/st.txt.
2268
f38f1d2a
SR
2269 stacktrace [FTRACE]
2270 Enabled the stack tracer on boot up.
2271
1da177e4
LT
2272 sti= [PARISC,HW]
2273 Format: <num>
2274 Set the STI (builtin display/keyboard on the HP-PARISC
2275 machines) console (graphic card) which should be used
2276 as the initial boot-console.
2277 See also comment in drivers/video/console/sticore.c.
2278
2279 sti_font= [HW]
2280 See comment in drivers/video/console/sticore.c.
2281
2282 stifb= [HW]
2283 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2284
42a7fc4a
GB
2285 sunrpc.pool_mode=
2286 [NFS]
2287 Control how the NFS server code allocates CPUs to
2288 service thread pools. Depending on how many NICs
2289 you have and where their interrupts are bound, this
2290 option will affect which CPUs will do NFS serving.
2291 Note: this parameter cannot be changed while the
2292 NFS server is running.
2293
2294 auto the server chooses an appropriate mode
2295 automatically using heuristics
2296 global a single global pool contains all CPUs
2297 percpu one pool for each CPU
2298 pernode one pool for each NUMA node (equivalent
2299 to global on non-NUMA machines)
2300
1da177e4 2301 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2302
1da177e4
LT
2303 switches= [HW,M68k]
2304
2305 sym53c416= [HW,SCSI]
2306 See header of drivers/scsi/sym53c416.c.
2307
5d6f647f
IM
2308 sysrq_always_enabled
2309 [KNL]
2310 Ignore sysrq setting - this boot parameter will
2311 neutralize any effect of /proc/sys/kernel/sysrq.
2312 Useful for debugging.
2313
1da177e4
LT
2314 t128= [HW,SCSI]
2315 See header of drivers/scsi/t128.c.
2316
2317 tdfx= [HW,DRM]
2318
77437fd4
DB
2319 test_suspend= [SUSPEND]
2320 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2321 standby suspend) as the system sleep state to briefly
2322 enter during system startup. The system is woken from
2323 this state using a wakeup-capable RTC alarm.
2324
1da177e4
LT
2325 thash_entries= [KNL,NET]
2326 Set number of hash buckets for TCP connection
2327
f8707ec9
LB
2328 thermal.act= [HW,ACPI]
2329 -1: disable all active trip points in all thermal zones
2330 <degrees C>: override all lowest active trip points
2331
c52a7419
LB
2332 thermal.crt= [HW,ACPI]
2333 -1: disable all critical trip points in all thermal zones
22a94d79 2334 <degrees C>: override all critical trip points
c52a7419 2335
f5487145
LB
2336 thermal.nocrt= [HW,ACPI]
2337 Set to disable actions on ACPI thermal zone
2338 critical and hot trip points.
2339
72b33ef8
LB
2340 thermal.off= [HW,ACPI]
2341 1: disable ACPI thermal control
2342
a70cdc52
LB
2343 thermal.psv= [HW,ACPI]
2344 -1: disable all passive trip points
ada9cfdd
RD
2345 <degrees C>: override all passive trip points to this
2346 value
a70cdc52 2347
730ff34d
LB
2348 thermal.tzp= [HW,ACPI]
2349 Specify global default ACPI thermal zone polling rate
2350 <deci-seconds>: poll all this frequency
2351 0: no polling (default)
2352
1da177e4
LT
2353 tmscsim= [HW,SCSI]
2354 See comment before function dc390_setup() in
2355 drivers/scsi/tmscsim.c.
2356
2b1a61f0
HC
2357 topology= [S390]
2358 Format: {off | on}
2359 Specify if the kernel should make use of the cpu
2360 topology informations if the hardware supports these.
2361 The scheduler will make use of these informations and
2362 e.g. base its process migration decisions on it.
2363 Default is off.
2364
1da177e4
LT
2365 tp720= [HW,PS2]
2366
2367 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2368 Format:
2369 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2370
395628ef
AK
2371 tsc= Disable clocksource-must-verify flag for TSC.
2372 Format: <string>
2373 [x86] reliable: mark tsc clocksource as reliable, this
2374 disables clocksource verification at runtime.
2375 Used to enable high-resolution timer mode on older
2376 hardware, and in virtualized environment.
2377
a9913044
RD
2378 turbografx.map[2|3]= [HW,JOY]
2379 TurboGraFX parallel port interface
2380 Format:
2381 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2382 See also Documentation/input/joystick-parport.txt
2383
2384 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2385 See header of drivers/scsi/u14-34f.c.
2386
2387 uart401= [HW,OSS]
2388 Format: <io>,<irq>
2389
2390 uart6850= [HW,OSS]
2391 Format: <io>,<irq>
2392
5f8364b7
AS
2393 uhci-hcd.ignore_oc=
2394 [USB] Ignore overcurrent events (default N).
2395 Some badly-designed motherboards generate lots of
2396 bogus events, for ports that aren't wired to
2397 anything. Set this parameter to avoid log spamming.
2398 Note that genuine overcurrent events won't be
2399 reported either.
2400
e3a61b0a
SA
2401 unknown_nmi_panic
2402 [X86-32,X86-64]
2403 Set unknown_nmi_panic=1 early on boot.
2404
b5e795f8
AS
2405 usbcore.autosuspend=
2406 [USB] The autosuspend time delay (in seconds) used
2407 for newly-detected USB devices (default 2). This
2408 is the time required before an idle device will be
2409 autosuspended. Devices for which the delay is set
eaafbc3a 2410 to a negative value won't be autosuspended at all.
b5e795f8 2411
fd7c519d
JK
2412 usbcore.usbfs_snoop=
2413 [USB] Set to log all usbfs traffic (default 0 = off).
2414
2415 usbcore.blinkenlights=
2416 [USB] Set to cycle leds on hubs (default 0 = off).
2417
2418 usbcore.old_scheme_first=
2419 [USB] Start with the old device initialization
2420 scheme (default 0 = off).
2421
2422 usbcore.use_both_schemes=
2423 [USB] Try the other device initialization scheme
2424 if the first one fails (default 1 = enabled).
2425
2426 usbcore.initial_descriptor_timeout=
2427 [USB] Specifies timeout for the initial 64-byte
2428 USB_REQ_GET_DESCRIPTOR request in milliseconds
2429 (default 5000 = 5.0 seconds).
2430
1da177e4
LT
2431 usbhid.mousepoll=
2432 [USBHID] The interval which mice are to be polled at.
a9913044 2433
d4f373e5
AS
2434 usb-storage.delay_use=
2435 [UMS] The delay in seconds before a new device is
2436 scanned for Logical Units (default 5).
2437
2438 usb-storage.quirks=
2439 [UMS] A list of quirks entries to supplement or
2440 override the built-in unusual_devs list. List
2441 entries are separated by commas. Each entry has
2442 the form VID:PID:Flags where VID and PID are Vendor
2443 and Product ID values (4-digit hex numbers) and
2444 Flags is a set of characters, each corresponding
2445 to a common usb-storage quirk flag as follows:
c838ea46
AS
2446 a = SANE_SENSE (collect more than 18 bytes
2447 of sense data);
d4f373e5
AS
2448 c = FIX_CAPACITY (decrease the reported
2449 device capacity by one sector);
c838ea46
AS
2450 h = CAPACITY_HEURISTICS (decrease the
2451 reported device capacity by one
2452 sector if the number is odd);
d4f373e5
AS
2453 i = IGNORE_DEVICE (don't bind to this
2454 device);
2455 l = NOT_LOCKABLE (don't try to lock and
2456 unlock ejectable media);
2457 m = MAX_SECTORS_64 (don't transfer more
2458 than 64 sectors = 32 KB at a time);
c838ea46
AS
2459 o = CAPACITY_OK (accept the capacity
2460 reported by the device);
d4f373e5
AS
2461 r = IGNORE_RESIDUE (the device reports
2462 bogus residue values);
2463 s = SINGLE_LUN (the device has only one
2464 Logical Unit);
2465 w = NO_WP_DETECT (don't test whether the
2466 medium is write-protected).
2467 Example: quirks=0419:aaf5:rl,0421:0433:rc
2468
200001eb
PJ
2469 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2470 kernel's map of available physical RAM.
2471
cd4f0ef7 2472 vdso= [X86-32,SH,x86-64]
1dbf527c 2473 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2474 vdso=1: enable VDSO (default)
2475 vdso=0: disable VDSO mapping
2476
af65d648
RM
2477 vdso32= [X86-32,X86-64]
2478 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2479 vdso32=1: enable 32-bit VDSO (default)
2480 vdso32=0: disable 32-bit VDSO mapping
2481
d080d397
YI
2482 vector= [IA-64,SMP]
2483 vector=percpu: enable percpu vector domain
2484
1da177e4
LT
2485 video= [FB] Frame buffer configuration
2486 See Documentation/fb/modedb.txt.
2487
cd4f0ef7 2488 vga= [BOOT,X86-32] Select a particular video mode
954a8b81 2489 See Documentation/x86/boot.txt and
a9913044 2490 Documentation/svga.txt.
1da177e4
LT
2491 Use vga=ask for menu.
2492 This is actually a boot loader parameter; the value is
2493 passed to the kernel using a special protocol.
2494
a9913044 2495 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2496 size of <nn>. This can be used to increase the
2497 minimum size (128MB on x86). It can also be used to
2498 decrease the size and leave more room for directly
2499 mapped kernel RAM.
2500
585c3047
PO
2501 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2502 Format: <command>
1da177e4 2503
585c3047
PO
2504 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2505 Format: <command>
2506
2507 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2508 Format: <command>
a9913044 2509
1da177e4
LT
2510 waveartist= [HW,OSS]
2511 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2512
1da177e4
LT
2513 wd33c93= [HW,SCSI]
2514 See header of drivers/scsi/wd33c93.c.
2515
2516 wd7000= [HW,SCSI]
2517 See header of drivers/scsi/wd7000.c.
2518
2519 wdt= [WDT] Watchdog
8dfe9c21 2520 See Documentation/watchdog/wdt.txt.
1da177e4
LT
2521
2522 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2523 xd_geo= See header of drivers/block/xd.c.
2524
2525 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2526 Format:
2527 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2528
ecb08d81
RD
2529 norandmaps Don't use address space randomization. Equivalent to
2530 echo 0 > /proc/sys/kernel/randomize_va_space
a62eaf15 2531
a9913044 2532______________________________________________________________________
1da177e4
LT
2533
2534TODO:
2535
2536 Add documentation for ALSA options.
2537 Add more DRM drivers.