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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.
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46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
11ef697b 52 LIBATA Libata driver is enabled
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53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
309e57df 61 MSI Message Signaled Interrupts (PCI).
c8facbb6 62 MTD MTD (Memory Technology Device) support is enabled.
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63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
734efb46 65 GENERIC_TIME The generic timeofday code is enabled.
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66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
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68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
7f785763 72 PCIE PCI Express support is enabled.
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73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
20510f2f 79 ROOTPLUG The example Root Plug LSM is enabled.
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80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
20510f2f 84 SECURITY Different security models are enabled.
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85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
e523d93c 87 SH SuperH architecture is enabled.
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88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
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90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
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92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 100 X86-32 X86-32, aka i386 architecture is enabled.
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101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
c0115606 104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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105
106In addition, the following text indicates that the option:
107
108 BUGS= Relates to possible processor bugs on the said processor.
109 KNL Is a kernel start-up parameter.
110 BOOT Is a boot loader parameter.
111
112Parameters denoted with BOOT are actually interpreted by the boot
113loader, and have no meaning to the kernel directly.
114Do not modify the syntax of boot loader parameters without extreme
115need or coordination with <Documentation/i386/boot.txt>.
116
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117There are also arch-specific kernel-parameters not documented here.
118See for example <Documentation/x86_64/boot-options.txt>.
119
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120Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
121a trailing = on the name of any parameter states that that parameter will
122be entered as an environment variable, whereas its absence indicates that
123it will appear as a kernel argument readable via /proc/cmdline by programs
124running once the system is up.
125
9c4751fd 126The number of kernel parameters is not limited, but the length of the
127complete command line (parameters including spaces etc.) is limited to
128a fixed number of characters. This limit depends on the architecture
129and is between 256 and 4096 characters. It is defined in the file
130./include/asm/setup.h as COMMAND_LINE_SIZE.
131
132
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133 acpi= [HW,ACPI,X86-64,i386]
134 Advanced Configuration and Power Interface
a9913044 135 Format: { force | off | ht | strict | noirq }
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136 force -- enable ACPI if default was off
137 off -- disable ACPI if default was on
138 noirq -- do not use ACPI for IRQ routing
139 ht -- run only enough ACPI to enable Hyper Threading
a9913044 140 strict -- Be less tolerant of platforms that are not
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141 strictly ACPI specification compliant.
142
53471121 143 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 144
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145 acpi_apic_instance= [ACPI, IOAPIC]
146 Format: <int>
147 2: use 2nd APIC table, if available
148 1,0: use 1st APIC table
4e381a4f 149 default: 0
a1fdcc0d 150
1da177e4 151 acpi_sleep= [HW,ACPI] Sleep options
bdfe6b7c 152 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
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153 See Documentation/power/video.txt for s3_bios and s3_mode.
154 s3_beep is for debugging; it makes the PC's speaker beep
155 as soon as the kernel's real-mode entry point is called.
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156 s4_nohwsig prevents ACPI hardware signature from being
157 used during resume from hibernation.
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158 old_ordering causes the ACPI 1.0 ordering of the _PTS
159 control method, wrt putting devices into low power
160 states, to be enforced (the ACPI 2.0 ordering of _PTS is
161 used by default).
a9913044 162
1da177e4 163 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 164 Format: { level | edge | high | low }
1da177e4 165
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166 acpi_irq_balance [HW,ACPI]
167 ACPI will balance active IRQs
168 default in APIC mode
1da177e4 169
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170 acpi_irq_nobalance [HW,ACPI]
171 ACPI will not move active IRQs (default)
172 default in PIC mode
1da177e4 173
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174 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
175 use by PCI
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176 Format: <irq>,<irq>...
177
a9913044 178 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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179 Format: <irq>,<irq>...
180
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181 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
182
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183 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
184 Format: To spoof as Windows 98: ="Microsoft Windows"
185
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186 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
187 acpi_osi="string1" # add string1 -- only one string
188 acpi_osi="!string2" # remove built-in string2
189 acpi_osi= # disable all strings
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190
191 acpi_serialize [HW,ACPI] force serialization of AML methods
192
193 acpi_skip_timer_override [HW,ACPI]
194 Recognize and ignore IRQ0/pin2 Interrupt Override.
195 For broken nForce2 BIOS resulting in XT-PIC timer.
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196 acpi_use_timer_override [HW,ACPI}
197 Use timer override. For some broken Nvidia NF5 boards
198 that require a timer override, but don't have
199 HPET
1da177e4 200
f989106c 201 acpi.debug_layer= [HW,ACPI]
1da177e4 202 Format: <int>
a9913044 203 Each bit of the <int> indicates an ACPI debug layer,
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204 1: enable, 0: disable. It is useful for boot time
205 debugging. After system has booted up, it can be set
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206 via /sys/module/acpi/parameters/debug_layer.
207 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
208 Available bits (add the numbers together) to enable debug output
209 for specific parts of the ACPI subsystem:
210 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
211 0x10 namespace 0x20 parser 0x40 dispatcher
212 0x80 executer 0x100 resources 0x200 acpica debugger
213 0x400 os services 0x800 acpica disassembler.
214 The number can be in decimal or prefixed with 0x in hex.
215 Warning: Many of these options can produce a lot of
216 output and make your system unusable. Be very careful.
217
218 acpi.debug_level= [HW,ACPI]
1da177e4 219 Format: <int>
a9913044 220 Each bit of the <int> indicates an ACPI debug level,
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221 1: enable, 0: disable. It is useful for boot time
222 debugging. After system has booted up, it can be set
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223 via /sys/module/acpi/parameters/debug_level.
224 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
225 Available bits (add the numbers together) to enable different
226 debug output levels of the ACPI subsystem:
227 0x01 error 0x02 warn 0x04 init 0x08 debug object
228 0x10 info 0x20 init names 0x40 parse 0x80 load
229 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
230 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
231 0x10000 resources 0x20000 user requests 0x40000 package.
232 The number can be in decimal or prefixed with 0x in hex.
233 Warning: Many of these options can produce a lot of
234 output and make your system unusable. Be very careful.
235
cd4f0ef7 236 acpi_pm_good [X86-32,X86-64]
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237 Override the pmtimer bug detection: force the kernel
238 to assume that this machine's pmtimer latches its value
239 and always returns good values.
240
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241 agp= [AGP]
242 { off | try_unsupported }
243 off: disable AGP support
244 try_unsupported: try to drive unsupported chipsets
245 (may crash computer or cause data corruption)
246
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247 enable_timer_pin_1 [i386,x86-64]
248 Enable PIN 1 of APIC timer
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249 Can be useful to work around chipset bugs
250 (in particular on some ATI chipsets).
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251 The kernel tries to set a reasonable default.
252
253 disable_timer_pin_1 [i386,x86-64]
254 Disable PIN 1 of APIC timer
255 Can be useful to work around chipset bugs.
256
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257 ad1848= [HW,OSS]
258 Format: <io>,<irq>,<dma>,<dma2>,<type>
259
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260 advansys= [HW,SCSI]
261 See header of drivers/scsi/advansys.c.
262
263 advwdt= [HW,WDT] Advantech WDT
264 Format: <iostart>,<iostop>
265
266 aedsp16= [HW,OSS] Audio Excel DSP 16
267 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
268 See also header of sound/oss/aedsp16.c.
a9913044 269
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270 aha152x= [HW,SCSI]
271 See Documentation/scsi/aha152x.txt.
272
273 aha1542= [HW,SCSI]
274 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
275
276 aic7xxx= [HW,SCSI]
277 See Documentation/scsi/aic7xxx.txt.
278
279 aic79xx= [HW,SCSI]
280 See Documentation/scsi/aic79xx.txt.
281
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282 amd_iommu= [HW,X86-84]
283 Pass parameters to the AMD IOMMU driver in the system.
284 Possible values are:
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285 isolate - enable device isolation (each device, as far
286 as possible, will get its own protection
287 domain)
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288 fullflush - enable flushing of IO/TLB entries when
289 they are unmapped. Otherwise they are
290 flushed before they will be reused, which
291 is a lot of faster
292
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293 amd_iommu_size= [HW,X86-64]
294 Define the size of the aperture for the AMD IOMMU
295 driver. Possible values are:
296 '32M', '64M' (default), '128M', '256M', '512M', '1G'
297
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298 amijoy.map= [HW,JOY] Amiga joystick support
299 Map of devices attached to JOY0DAT and JOY1DAT
300 Format: <a>,<b>
301 See also Documentation/kernel/input/joystick.txt
302
303 analog.map= [HW,JOY] Analog joystick and gamepad support
304 Specifies type or capabilities of an analog joystick
305 connected to one of 16 gameports
306 Format: <type1>,<type2>,..<type16>
307
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308 apc= [HW,SPARC]
309 Power management functions (SPARCstation-4/5 + deriv.)
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310 Format: noidle
311 Disable APC CPU standby support. SPARCstation-Fox does
312 not play well with APC CPU idle - disable it if you have
313 APC and your system crashes randomly.
314
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315 apic= [APIC,i386] Advanced Programmable Interrupt Controller
316 Change the output verbosity whilst booting
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317 Format: { quiet (default) | verbose | debug }
318 Change the amount of debugging information output
319 when initialising the APIC and IO-APIC components.
a9913044 320
1da177e4 321 apm= [APM] Advanced Power Management
71f77055 322 See header of arch/x86/kernel/apm_32.c.
1da177e4 323
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324 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
325 Format: <io>,<irq>,<nodeID>
326
327 ataflop= [HW,M68k]
328
329 atarimouse= [HW,MOUSE] Atari Mouse
330
331 atascsi= [HW,SCSI] Atari SCSI
332
333 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
334 EzKey and similar keyboards
335
336 atkbd.reset= [HW] Reset keyboard during initialization
337
a9913044
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338 atkbd.set= [HW] Select keyboard code set
339 Format: <int> (2 = AT (default), 3 = PS/2)
1da177e4
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340
341 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
342 keyboards
343
344 atkbd.softraw= [HW] Choose between synthetic and real raw mode
345 Format: <bool> (0 = real, 1 = synthetic (default))
a9913044
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346
347 atkbd.softrepeat= [HW]
348 Use software keyboard repeat
1da177e4
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349
350 autotest [IA64]
351
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352 baycom_epp= [HW,AX25]
353 Format: <io>,<mode>
a9913044 354
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LT
355 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
356 Format: <io>,<mode>
357 See header of drivers/net/hamradio/baycom_par.c.
358
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359 baycom_ser_fdx= [HW,AX25]
360 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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361 Format: <io>,<irq>,<mode>[,<baud>]
362 See header of drivers/net/hamradio/baycom_ser_fdx.c.
363
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364 baycom_ser_hdx= [HW,AX25]
365 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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366 Format: <io>,<irq>,<mode>
367 See header of drivers/net/hamradio/baycom_ser_hdx.c.
368
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369 boot_delay= Milliseconds to delay each printk during boot.
370 Values larger than 10 seconds (10000) are changed to
371 no delay (0).
372 Format: integer
373
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374 bootmem_debug [KNL] Enable bootmem allocator debug messages.
375
1da177e4 376 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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377 bttv.radio= Most important insmod options are available as
378 kernel args too.
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379 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
380 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
381
382 BusLogic= [HW,SCSI]
383 See drivers/scsi/BusLogic.c, comment before function
384 BusLogic_ParseDriverOptions().
385
386 c101= [NET] Moxa C101 synchronous serial card
387
cd4f0ef7 388 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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389 Sometimes CPU hardware bugs make them report the cache
390 size incorrectly. The kernel will attempt work arounds
391 to fix known problems, but for some CPUs it is not
392 possible to determine what the correct size should be.
393 This option provides an override for these situations.
394
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395 security= [SECURITY] Choose a security module to enable at boot.
396 If this boot parameter is not specified, only the first
397 security module asking for security registration will be
398 loaded. An invalid security module name will be treated
399 as if no module has been chosen.
400
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401 capability.disable=
402 [SECURITY] Disable capabilities. This would normally
403 be used only if an alternative security model is to be
404 configured. Potentially dangerous and should only be
405 used if you are entirely sure of the consequences.
406
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407 ccw_timeout_log [S390]
408 See Documentation/s390/CommonIO for details.
1da177e4 409
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410 cgroup_disable= [KNL] Disable a particular controller
411 Format: {name of the controller(s) to disable}
412 {Currently supported controllers - "memory"}
413
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414 checkreqprot [SELINUX] Set initial checkreqprot flag value.
415 Format: { "0" | "1" }
416 See security/selinux/Kconfig help text.
a9913044
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417 0 -- check protection applied by kernel (includes
418 any implied execute protection).
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419 1 -- check protection requested by application.
420 Default value is set via a kernel config option.
a9913044
RD
421 Value can be changed at runtime via
422 /selinux/checkreqprot.
423
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SO
424 cio_ignore= [S390]
425 See Documentation/s390/CommonIO for details.
426
cd4f0ef7 427 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 428 [Deprecated]
3f6dee9b 429 Forces specified clocksource (if available) to be used
734efb46 430 when calculating gettimeofday(). If specified
3f6dee9b 431 clocksource is not available, it defaults to PIT.
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LT
432 Format: { pit | tsc | cyclone | pmtmr }
433
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RD
434 clocksource= [GENERIC_TIME] Override the default clocksource
435 Format: <string>
436 Override the default clocksource and use the clocksource
437 with the name specified.
438 Some clocksource names to choose from, depending on
439 the platform:
440 [all] jiffies (this is the base, fallback clocksource)
441 [ACPI] acpi_pm
442 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
443 pxa_timer,timer3,32k_counter,timer0_1
444 [AVR32] avr32
cd4f0ef7 445 [X86-32] pit,hpet,tsc,vmi-timer;
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RD
446 scx200_hrt on Geode; cyclone on IBM x440
447 [MIPS] MIPS
448 [PARISC] cr16
449 [S390] tod
450 [SH] SuperH
451 [SPARC64] tick
452 [X86-64] hpet,tsc
453
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454 clearcpuid=BITNUM [X86]
455 Disable CPUID feature X for the kernel. See
456 include/asm-x86/cpufeature.h for the valid bit numbers.
457 Note the Linux specific bits are not necessarily
458 stable over kernel options, but the vendor specific
459 ones should be.
460 Also note that user programs calling CPUID directly
461 or using the feature without checking anything
462 will still see it. This just prevents it from
463 being used by the kernel or shown in /proc/cpuinfo.
464 Also note the kernel might malfunction if you disable
465 some critical bits.
466
a25bd949
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467 code_bytes [IA32/X86_64] How many bytes of object code to print
468 in an oops report.
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CE
469 Range: 0 - 8192
470 Default: 64
471
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TG
472 hpet= [X86-32,HPET] option to control HPET usage
473 Format: { enable (default) | disable | force }
474 disable: disable HPET and use PIT instead
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475 force: allow force enabled of undocumented chips (ICH4,
476 VIA, nVidia)
1da177e4 477
1da177e4 478 com20020= [HW,NET] ARCnet - COM20020 chipset
a9913044
RD
479 Format:
480 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
1da177e4
LT
481
482 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
483 Format: <io>[,<irq>]
484
a9913044
RD
485 com90xx= [HW,NET]
486 ARCnet - COM90xx chipset (memory-mapped buffers)
1da177e4
LT
487 Format: <io>[,<irq>[,<memstart>]]
488
489 condev= [HW,S390] console device
490 conmode=
a9913044 491
1da177e4
LT
492 console= [KNL] Output console device and options.
493
494 tty<n> Use the virtual console device <n>.
495
496 ttyS<n>[,options]
f1a1c2dc 497 ttyUSB0[,options]
1da177e4 498 Use the specified serial port. The options are of
f1a1c2dc
RD
499 the form "bbbbpnf", where "bbbb" is the baud rate,
500 "p" is parity ("n", "o", or "e"), "n" is number of
501 bits, and "f" is flow control ("r" for RTS or
502 omit it). Default is "9600n8".
503
504 See Documentation/serial-console.txt for more
505 information. See
506 Documentation/networking/netconsole.txt for an
507 alternative.
1da177e4 508
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YL
509 uart[8250],io,<addr>[,options]
510 uart[8250],mmio,<addr>[,options]
1da177e4
LT
511 Start an early, polled-mode console on the 8250/16550
512 UART at the specified I/O port or MMIO address,
513 switching to the matching ttyS device later. The
514 options are the same as for ttyS, above.
515
f7511d5f
ST
516 If the device connected to the port is not a TTY but a braille
517 device, prepend "brl," before the device type, for instance
518 console=brl,ttyS0
519 For now, only VisioBraille is supported.
520
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YL
521 earlycon= [KNL] Output early console device and options.
522 uart[8250],io,<addr>[,options]
523 uart[8250],mmio,<addr>[,options]
524 Start an early, polled-mode console on the 8250/16550
525 UART at the specified I/O port or MMIO address.
526 The options are the same as for ttyS, above.
527
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AS
528 no_console_suspend
529 [HW] Never suspend the console
530 Disable suspending of consoles during suspend and
531 hibernate operations. Once disabled, debugging
532 messages can reach various consoles while the rest
533 of the system is being put to sleep (ie, while
534 debugging driver suspend/resume hooks). This may
535 not work reliably with all consoles, but is known
536 to work with serial and VGA consoles.
537
1da177e4 538 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
539 Format:
540 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 541
dc009d92
EB
542 crashkernel=nn[KMG]@ss[KMG]
543 [KNL] Reserve a chunk of physical memory to
544 hold a kernel to switch to with kexec on panic.
545
fb391599
BW
546 crashkernel=range1:size1[,range2:size2,...][@offset]
547 [KNL] Same as above, but depends on the memory
548 in the running system. The syntax of range is
549 start-[end] where start and end are both
550 a memory unit (amount[KMG]). See also
551 Documentation/kdump/kdump.txt for a example.
552
1da177e4
LT
553 cs4232= [HW,OSS]
554 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
555
556 cs89x0_dma= [HW,NET]
557 Format: <dma>
558
559 cs89x0_media= [HW,NET]
560 Format: { rj45 | aui | bnc }
a9913044 561
a9913044 562 dasd= [HW,NET]
1da177e4
LT
563 See header of drivers/s390/block/dasd_devmap.c.
564
565 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
566 (one device per port)
567 Format: <port#>,<type>
568 See also Documentation/input/joystick-parport.txt
569
570 debug [KNL] Enable kernel debugging (events log level).
571
cae2ed9a
IM
572 debug_locks_verbose=
573 [KNL] verbose self-tests
574 Format=<0|1>
575 Print debugging info while doing the locking API
576 self-tests.
577 We default to 0 (no extra messages), setting it to
578 1 will print _a lot_ more information - normally
579 only useful to kernel developers.
580
3ac7fe5a
TG
581 debug_objects [KNL] Enable object debugging
582
d3af01f1
TG
583 debugpat [X86] Enable PAT debugging
584
2d27a966 585 decnet.addr= [HW,NET]
1da177e4
LT
586 Format: <area>[,<node>]
587 See also Documentation/networking/decnet.txt.
588
ecb77fa9 589 vt.default_blu= [VT]
55ff9780
AD
590 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
591 Change the default blue palette of the console.
592 This is a 16-member array composed of values
593 ranging from 0-255.
594
ecb77fa9 595 vt.default_grn= [VT]
55ff9780
AD
596 Format: <green0>,<green1>,<green2>,...,<green15>
597 Change the default green palette of the console.
598 This is a 16-member array composed of values
599 ranging from 0-255.
600
ecb77fa9 601 vt.default_red= [VT]
55ff9780
AD
602 Format: <red0>,<red1>,<red2>,...,<red15>
603 Change the default red palette of the console.
604 This is a 16-member array composed of values
605 ranging from 0-255.
606
ecb77fa9
ST
607 vt.default_utf8=
608 [VT]
55ff9780
AD
609 Format=<0|1>
610 Set system-wide default UTF-8 mode for all tty's.
ecb77fa9
ST
611 Default is 1, i.e. UTF-8 mode is enabled for all
612 newly opened terminals.
55ff9780 613
1da177e4
LT
614 dhash_entries= [KNL]
615 Set number of hash buckets for dentry cache.
a9913044 616
1da177e4
LT
617 digi= [HW,SERIAL]
618 IO parameters + enable/disable command.
619
620 digiepca= [HW,SERIAL]
621 See drivers/char/README.epca and
622 Documentation/digiepca.txt.
623
95ffa243
YL
624 disable_mtrr_cleanup [X86]
625 enable_mtrr_cleanup [X86]
626 The kernel tries to adjust MTRR layout from continuous
627 to discrete, to make X server driver able to add WB
628 entry later. This parameter enables/disables that.
629
630 mtrr_chunk_size=nn[KMG] [X86]
631 used for mtrr cleanup. It is largest continous chunk
632 that could hold holes aka. UC entries.
633
634 mtrr_gran_size=nn[KMG] [X86]
12031a62
YL
635 Used for mtrr cleanup. It is granularity of mtrr block.
636 Default is 1.
637 Large value could prevent small alignment from
638 using up MTRRs.
639
640 mtrr_spare_reg_nr=n [X86]
641 Format: <integer>
642 Range: 0,7 : spare reg number
643 Default : 1
644 Used for mtrr cleanup. It is spare mtrr entries number.
645 Set to 2 or more if your graphical card needs more.
95ffa243 646
093af8d7 647 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
652
1da177e4
LT
653 dmasound= [HW,OSS] Sound subsystem buffers
654
655 dscc4.setup= [NET]
656
657 dtc3181e= [HW,SCSI]
658
0ae53640 659 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
1da177e4
LT
660 earlyprintk=vga
661 earlyprintk=serial[,ttySn[,baudrate]]
5c05917e 662 earlyprintk=dbgp
1da177e4 663
a9913044 664 Append ",keep" to not disable it when the real console
1da177e4
LT
665 takes over.
666
5c05917e 667 Only vga or serial or usb debug port at a time.
1da177e4
LT
668
669 Currently only ttyS0 and ttyS1 are supported.
670
671 Interaction with the standard serial driver is not
672 very good.
673
674 The VGA output is eventually overwritten by the real
675 console.
676
677 eata= [HW,SCSI]
678
1da177e4 679 edd= [EDD]
8c4dd606 680 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 681
1da177e4
LT
682 eisa_irq_edge= [PARISC,HW]
683 See header of drivers/parisc/eisa.c.
684
cd4f0ef7 685 elanfreq= [X86-32]
1da177e4 686 See comment before function elanfreq_setup() in
71f77055 687 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
688
689 elevator= [IOSCHED]
16ab3adf 690 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
691 See Documentation/block/as-iosched.txt and
692 Documentation/block/deadline-iosched.txt for details.
693
e515a0d6 694 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
a9913044 695 Specifies physical address of start of kernel core
aac04b32
VG
696 image elf header. Generally kexec loader will
697 pass this option to capture kernel.
698 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
699
700 enforcing [SELINUX] Set initial enforcing status.
701 Format: {"0" | "1"}
702 See security/selinux/Kconfig help text.
703 0 -- permissive (log only, no denials).
704 1 -- enforcing (deny and log).
705 Default value is 0.
706 Value can be changed at runtime via /selinux/enforce.
707
1da177e4
LT
708 es1371= [HW,OSS]
709 Format: <spdif>,[<nomix>,[<amplifier>]]
710 See also header of sound/oss/es1371.c.
a9913044 711
1da177e4
LT
712 ether= [HW,NET] Ethernet cards parameters
713 This option is obsoleted by the "netdev=" option, which
714 has equivalent usage. See its documentation for details.
715
716 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
717 Format: <io>[,<irq>]
718
de1ba09b
AM
719 failslab=
720 fail_page_alloc=
721 fail_make_request=[KNL]
722 General fault injection mechanism.
723 Format: <interval>,<probability>,<space>,<times>
724 See also /Documentation/fault-injection/.
725
1da177e4
LT
726 fd_mcs= [HW,SCSI]
727 See header of drivers/scsi/fd_mcs.c.
728
729 fdomain= [HW,SCSI]
730 See header of drivers/scsi/fdomain.c.
731
732 floppy= [HW]
733 See Documentation/floppy.txt.
734
f13ae30e
AC
735 force_pal_cache_flush
736 [IA-64] Avoid check_sal_cache_flush which may hang on
737 buggy SAL_CACHE_FLUSH implementations. Using this
738 parameter will force ia64_sal_cache_flush to call
739 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
740
1da177e4
LT
741 gamecon.map[2|3]=
742 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
743 support via parallel port (up to 5 devices per port)
744 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
745 See also Documentation/input/joystick-parport.txt
746
747 gamma= [HW,DRM]
748
aaf23042
YL
749 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
750 Format: off | on
751 default: on
752
1da177e4
LT
753 gdth= [HW,SCSI]
754 See header of drivers/scsi/gdth.c.
755
756 gpt [EFI] Forces disk with valid GPT signature but
757 invalid Protective MBR to be treated as GPT.
758
1da177e4
LT
759 gvp11= [HW,SCSI]
760
761 hashdist= [KNL,NUMA] Large hashes allocated during boot
762 are distributed across NUMA nodes. Defaults on
763 for IA-64, off otherwise.
a9913044 764 Format: 0 | 1 (for off | on)
1da177e4
LT
765
766 hcl= [IA-64] SGI's Hardware Graph compatibility layer
767
768 hd= [EIDE] (E)IDE hard drive subsystem geometry
769 Format: <cyl>,<head>,<sect>
770
1da177e4
LT
771 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
772 size of <nn>. This works even on boxes that have no
773 highmem otherwise. This also works to reduce highmem
774 size on bigger boxes.
775
54cdfdb4
TG
776 highres= [KNL] Enable/disable high resolution timer mode.
777 Valid parameters: "on", "off"
778 Default: "on"
779
1da177e4
LT
780 hisax= [HW,ISDN]
781 See Documentation/isdn/README.HiSax.
782
b4718e62
AK
783 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
784 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
785 On x86-64 and powerpc, this option can be specified
786 multiple times interleaved with hugepages= to reserve
787 huge pages of different sizes. Valid pages sizes on
788 x86-64 are 2M (when the CPU supports "pse") and 1G
789 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
790 Note that 1GB pages can only be allocated at boot time
791 using hugepages= and not freed afterwards.
e11bfbfc
NP
792 default_hugepagesz=
793 [same as hugepagesz=] The size of the default
794 HugeTLB page size. This is the size represented by
795 the legacy /proc/ hugepages APIs, used for SHM, and
796 default size when mounting hugetlbfs filesystems.
797 Defaults to the default architecture's huge page size
798 if not specified.
1da177e4 799
6902aa84
PM
800 hlt [BUGS=ARM,SH]
801
36d95739 802 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 803 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
804 i8042.dumbkbd [HW] Pretend that controller can only read data from
805 keyboard and cannot control its state
1da177e4
LT
806 (Don't attempt to blink the leds)
807 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 808 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
809 i8042.noloop [HW] Disable the AUX Loopback command while probing
810 for the AUX port
1da177e4
LT
811 i8042.nomux [HW] Don't check presence of an active multiplexing
812 controller
813 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
814 controllers
815 i8042.panicblink=
816 [HW] Frequency with which keyboard LEDs should blink
817 when kernel panics (default is 0.5 sec)
818 i8042.reset [HW] Reset the controller during init and cleanup
819 i8042.unlock [HW] Unlock (ignore) the keylock
820
821 i810= [HW,DRM]
822
e70c9d5e
DT
823 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
824 indicates that the driver is running on unsupported
825 hardware.
1da177e4
LT
826 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
827 does not match list of supported models.
828 i8k.power_status
829 [HW] Report power status in /proc/i8k
830 (disabled by default)
831 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
832 capability is set.
833
834 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
835 See Documentation/mca.txt.
836
837 icn= [HW,ISDN]
838 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
839
840 ide= [HW] (E)IDE subsystem
a594eeb1 841 Format: ide=nodma or ide=doubler
1c10e938 842 See Documentation/ide/ide.txt.
1da177e4 843
1da177e4 844 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
1c10e938 845 See Documentation/ide/ide.txt.
1da177e4 846
f039b754 847 idle= [X86]
da5e09a1 848 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
f039b754
AK
849 Poll forces a polling idle loop that can slightly improves the performance
850 of waking up a idle CPU, but will use a lot of power and make the system
851 run hot. Not recommended.
852 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
853 to not use it because it doesn't save as much power as a normal idle
854 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
855 as idle=poll.
c1e3b377
ZY
856 idle=halt. Halt is forced to be used for CPU idle.
857 In such case C2/C3 won't be used again.
da5e09a1 858 idle=nomwait. Disable mwait for CPU C-states
a9913044 859
594765a7
DC
860 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
861 Claim all unknown PCI IDE storage controllers.
862
79290822
IM
863 ignore_loglevel [KNL]
864 Ignore loglevel setting - this will print /all/
865 kernel messages to the console. Useful for debugging.
866
1da177e4
LT
867 ihash_entries= [KNL]
868 Set number of hash buckets for inode cache.
869
870 in2000= [HW,SCSI]
871 See header of drivers/scsi/in2000.c.
872
873 init= [KNL]
874 Format: <full_path>
875 Run specified binary instead of /sbin/init as init
876 process.
877
878 initcall_debug [KNL] Trace initcalls as they are executed. Useful
879 for working out where the kernel is dying during
880 startup.
881
882 initrd= [BOOT] Specify the location of the initial ramdisk
883
884 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
885 Format: <irq>
886
887 inttest= [IA64]
888
b552da87
PM
889 iommu= [x86]
890 off
891 force
892 noforce
893 biomerge
894 panic
895 nopanic
896 merge
897 nomerge
898 forcesac
899 soft
900
901
ba395927
KA
902 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
903 off
904 Disable intel iommu driver.
905 igfx_off [Default Off]
906 By default, gfx is mapped as normal device. If a gfx
907 device has a dedicated DMAR unit, the DMAR unit is
908 bypassed by not enabling DMAR with this option. In
909 this case, gfx device will use physical address for
910 DMA.
7d3b03ce
KA
911 forcedac [x86_64]
912 With this option iommu will not optimize to look
913 for io virtual address below 32 bit forcing dual
914 address cycle on pci bus for cards supporting greater
915 than 32 bit addressing. The default is to look
916 for translation below 32 bit and if not available
917 then look in the higher range.
5e0d2a6f 918 strict [Default Off]
919 With this option on every unmap_single operation will
920 result in a hardware IOTLB flush operation as opposed
921 to batching them for performance.
ba395927 922
b02aae9c 923 io_delay= [X86-32,X86-64] I/O delay method
6e7c4025
IM
924 0x80
925 Standard port 0x80 based delay
926 0xed
927 Alternate port 0xed based delay (needed on some systems)
b02aae9c 928 udelay
6e7c4025
IM
929 Simple two microseconds delay
930 none
931 No delay
b02aae9c 932
1da177e4
LT
933 io7= [HW] IO7 for Marvel based alpha systems
934 See comment before marvel_specify_io7 in
935 arch/alpha/kernel/core_marvel.c.
936
937 ip= [IP_PNP]
6ded55da 938 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
939
940 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
941 See comment before ip2_setup() in
942 drivers/char/ip2/ip2base.c.
1da177e4
LT
943
944 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
945 See header of drivers/scsi/ips.c.
946
72c4a13a
SH
947 ports= [IP_VS_FTP] IPVS ftp helper module
948 Default is 21.
949 Up to 8 (IP_VS_APP_MAX_PORTS) ports
950 may be specified.
951 Format: <port>,<port>....
952
200803df
AC
953 irqfixup [HW]
954 When an interrupt is not handled search all handlers
955 for it. Intended to get systems with badly broken
956 firmware running.
957
958 irqpoll [HW]
959 When an interrupt is not handled search all handlers
960 for it. Also check all handlers each timer
961 interrupt. Intended to get systems with badly broken
962 firmware running.
963
1da177e4 964 isapnp= [ISAPNP]
a9913044 965 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
966
967 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
968 Format:
969 <cpu number>,...,<cpu number>
970 or
971 <cpu number>-<cpu number> (must be a positive range in ascending order)
972 or a mixture
973 <cpu number>,...,<cpu number>-<cpu number>
1da177e4
LT
974 This option can be used to specify one or more CPUs
975 to isolate from the general SMP balancing and scheduling
976 algorithms. The only way to move a process onto or off
977 an "isolated" CPU is via the CPU affinity syscalls.
978 <cpu number> begins at 0 and the maximum value is
979 "number of CPUs in system - 1".
980
981 This option is the preferred way to isolate CPUs. The
a9913044
RD
982 alternative -- manually setting the CPU mask of all
983 tasks in the system -- can cause problems and
984 suboptimal load balancer performance.
1da177e4 985
a9913044 986 iucv= [HW,NET]
1da177e4
LT
987
988 js= [HW,JOY] Analog joystick
989 See Documentation/input/joystick.txt.
990
cd4f0ef7 991 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
ed7ed365
MG
992 specifies the amount of memory usable by the kernel
993 for non-movable allocations. The requested amount is
994 spread evenly throughout all nodes in the system. The
995 remaining memory in each node is used for Movable
996 pages. In the event, a node is too small to have both
997 kernelcore and Movable pages, kernelcore pages will
998 take priority and other nodes will have a larger number
999 of kernelcore pages. The Movable zone is used for the
1000 allocation of pages that may be reclaimed or moved
1001 by the page migration subsystem. This means that
1002 HugeTLB pages may not be allocated from this zone.
1003 Note that allocations like PTEs-from-HighMem still
1004 use the HighMem zone if it exists, and the Normal
1005 zone if it does not.
1006
cd4f0ef7 1007 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
7e63efef
MG
1008 is similar to kernelcore except it specifies the
1009 amount of memory used for migratable allocations.
1010 If both kernelcore and movablecore is specified,
1011 then kernelcore will be at *least* the specified
1012 value but may be more. If movablecore on its own
1013 is specified, the administrator must be careful
1014 that the amount of memory usable for all allocations
1015 is not too small.
1016
1da177e4
LT
1017 keepinitrd [HW,ARM]
1018
cd4f0ef7 1019 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1da177e4
LT
1020 in oops dumps.
1021
6cdf6e06
JW
1022 kgdboc= [HW] kgdb over consoles.
1023 Requires a tty driver that supports console polling.
1024 (only serial suported for now)
1025 Format: <serial_device>[,baud]
1026
9bed90c6
FF
1027 kmac= [MIPS] korina ethernet MAC address.
1028 Configure the RouterBoard 532 series on-chip
1029 Ethernet adapter MAC address.
1030
1da177e4
LT
1031 l2cr= [PPC]
1032
a78bfbfc
RB
1033 l3cr= [PPC]
1034
cd4f0ef7 1035 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1036 disabled it.
1da177e4 1037
cd4f0ef7 1038 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
e585bef8
TG
1039 C2 power state.
1040
fcb71f6f
FC
1041 libata.dma= [LIBATA] DMA control
1042 libata.dma=0 Disable all PATA and SATA DMA
1043 libata.dma=1 PATA and SATA Disk DMA only
1044 libata.dma=2 ATAPI (CDROM) DMA only
1045 libata.dma=4 Compact Flash DMA only
1046 Combinations also work, so libata.dma=3 enables DMA
1047 for disks and CDROMs, but not CFs.
1048
78e70c23
DJ
1049 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1050 when set.
1051 Format: <int>
1052
33267325
TH
1053 libata.force= [LIBATA] Force configurations. The format is comma
1054 separated list of "[ID:]VAL" where ID is
1055 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1056 matching port, link or device. Basically, it matches
1057 the ATA ID string printed on console by libata. If
1058 the whole ID part is omitted, the last PORT and DEVICE
1059 values are used. If ID hasn't been specified yet, the
1060 configuration applies to all ports, links and devices.
1061
1062 If only DEVICE is omitted, the parameter applies to
1063 the port and all links and devices behind it. DEVICE
1064 number of 0 either selects the first device or the
1065 first fan-out link behind PMP device. It does not
1066 select the host link. DEVICE number of 15 selects the
1067 host link and device attached to it.
1068
1069 The VAL specifies the configuration to force. As long
1070 as there's no ambiguity shortcut notation is allowed.
1071 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1072 The following configurations can be forced.
1073
1074 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1075 Any ID with matching PORT is used.
1076
1077 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1078
1079 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1080 udma[/][16,25,33,44,66,100,133] notation is also
1081 allowed.
1082
1083 * [no]ncq: Turn on or off NCQ.
1084
05944bdf
TH
1085 * nohrst, nosrst, norst: suppress hard, soft
1086 and both resets.
1087
33267325
TH
1088 If there are multiple matching configurations changing
1089 the same attribute, the last one is used.
1090
1da177e4
LT
1091 load_ramdisk= [RAM] List of ramdisks to load from floppy
1092 See Documentation/ramdisk.txt.
1093
a6b25b67
RD
1094 lockd.nlm_grace_period=P [NFS] Assign grace period.
1095 Format: <integer>
1da177e4 1096
a6b25b67
RD
1097 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1098 Format: <integer>
1099
1100 lockd.nlm_timeout=T [NFS] Assign timeout value.
1101 Format: <integer>
1102
1103 lockd.nlm_udpport=M [NFS] Assign UDP port.
1104 Format: <integer>
1da177e4
LT
1105
1106 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1107 Format: <irq>
1108
1109 loglevel= All Kernel Messages with a loglevel smaller than the
1110 console loglevel will be printed to the console. It can
1111 also be changed with klogd or other programs. The
1112 loglevels are defined as follows:
1113
1114 0 (KERN_EMERG) system is unusable
1115 1 (KERN_ALERT) action must be taken immediately
1116 2 (KERN_CRIT) critical conditions
1117 3 (KERN_ERR) error conditions
1118 4 (KERN_WARNING) warning conditions
1119 5 (KERN_NOTICE) normal but significant condition
1120 6 (KERN_INFO) informational
1121 7 (KERN_DEBUG) debug-level messages
1122
1123 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1124 Format: { n | nk | nM }
1125 n must be a power of two. The default size
1126 is set in the kernel config file.
1da177e4 1127
accaa24c
RD
1128 logo.nologo [FB] Disables display of the built-in Linux logo.
1129 This may be used to provide more screen space for
1130 kernel log messages and is useful when debugging
1131 kernel boot problems.
1132
1da177e4
LT
1133 lp=0 [LP] Specify parallel ports to use, e.g,
1134 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1135 lp=reset first parallel port). 'lp=0' disables the
1136 lp=auto printer driver. 'lp=reset' (which can be
1137 specified in addition to the ports) causes
1138 attached printers to be reset. Using
1139 lp=port1,port2,... specifies the parallel ports
1140 to associate lp devices with, starting with
1141 lp0. A port specification may be 'none' to skip
1142 that lp device, or a parport name such as
1143 'parport0'. Specifying 'lp=auto' instead of a
1144 port specification list means that device IDs
1145 from each port should be examined, to see if
1146 an IEEE 1284-compliant printer is attached; if
1147 so, the driver will manage that printer.
1148 See also header of drivers/char/lp.c.
1149
1150 lpj=n [KNL]
1151 Sets loops_per_jiffy to given constant, thus avoiding
1152 time-consuming boot-time autodetection (up to 250 ms per
1153 CPU). 0 enables autodetection (default). To determine
1154 the correct value for your kernel, boot with normal
1155 autodetection and see what value is printed. Note that
1156 on SMP systems the preset will be applied to all CPUs,
1157 which is likely to cause problems if your CPUs need
1158 significantly divergent settings. An incorrect value
1159 will cause delays in the kernel to be wrong, leading to
1160 unpredictable I/O errors and other breakage. Although
1161 unlikely, in the extreme case this might damage your
1162 hardware.
1163
1164 ltpc= [NET]
1165 Format: <io>,<irq>,<dma>
1166
a9913044
RD
1167 mac5380= [HW,SCSI] Format:
1168 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1169
a9913044
RD
1170 machvec= [IA64] Force the use of a particular machine-vector
1171 (machvec) in a generic kernel.
1172 Example: machvec=hpzx1_swiotlb
1da177e4 1173
a9913044 1174 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
1175 be mounted
1176 Format: <1-256>
1177
1178 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1179 should make use of. maxcpus=n : n >= 0 limits the
1180 kernel to using 'n' processors. n=0 is a special case,
1181 it is equivalent to "nosmp", which also disables
1182 the IO APIC.
1da177e4 1183
2b2c3750
BP
1184 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1185 equal to this physical address is ignored.
1186
a9913044 1187 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1188 Should be between 1 and 2^32-1.
1189
1190 max_report_luns=
a9913044 1191 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1192 Should be between 1 and 16384.
1193
1da177e4
LT
1194 mcatest= [IA-64]
1195
cd4f0ef7 1196 mce [X86-32] Machine Check Exception
1da177e4 1197
909dd324
AK
1198 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1199
1da177e4
LT
1200 md= [HW] RAID subsystems devices and level
1201 See Documentation/md.txt.
a9913044 1202
1da177e4
LT
1203 mdacon= [MDA]
1204 Format: <first>,<last>
1205 Specifies range of consoles to be captured by the MDA.
a9913044 1206
1da177e4
LT
1207 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1208 Amount of memory to be used when the kernel is not able
1209 to see the whole system memory or for test.
cd4f0ef7 1210 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1211 address space collisions. Without memmap= PCI devices
1212 could be placed at addresses belonging to unused RAM.
1213
cd4f0ef7 1214 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1215 memory.
1216
6902aa84
PM
1217 memchunk=nn[KMG]
1218 [KNL,SH] Allow user to override the default size for
1219 per-device physically contiguous DMA buffers.
1220
cd4f0ef7 1221 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1da177e4
LT
1222 E820 memory map, as specified by the user.
1223 Such memmap=exactmap lines can be constructed based on
1224 BIOS output or other requirements. See the memmap=nn@ss
1225 option description.
1226
1227 memmap=nn[KMG]@ss[KMG]
1228 [KNL] Force usage of a specific region of memory
1229 Region of memory to be used, from ss to ss+nn.
1230
1231 memmap=nn[KMG]#ss[KMG]
1232 [KNL,ACPI] Mark specific memory as ACPI data.
1233 Region of memory to be used, from ss to ss+nn.
1234
1235 memmap=nn[KMG]$ss[KMG]
1236 [KNL,ACPI] Mark specific memory as reserved.
1237 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1238 Example: Exclude memory from 0x18690000-0x1869ffff
1239 memmap=64K$0x18690000
1240 or
1241 memmap=0x10000$0x18690000
1da177e4 1242
9f077871
JF
1243 memory_corruption_check=0/1 [X86]
1244 Some BIOSes seem to corrupt the first 64k of
1245 memory when doing things like suspend/resume.
1246 Setting this option will scan the memory
1247 looking for corruption. Enabling this will
1248 both detect corruption and prevent the kernel
1249 from using the memory being corrupted.
1250 However, its intended as a diagnostic tool; if
1251 repeatable BIOS-originated corruption always
1252 affects the same memory, you can use memmap=
1253 to prevent the kernel from using that memory.
1254
1255 memory_corruption_check_size=size [X86]
1256 By default it checks for corruption in the low
1257 64k, making this memory unavailable for normal
1258 use. Use this parameter to scan for
1259 corruption in more or less memory.
1260
1261 memory_corruption_check_period=seconds [X86]
1262 By default it checks for corruption every 60
1263 seconds. Use this parameter to check at some
1264 other rate. 0 disables periodic checking.
1265
caadbdce 1266 memtest= [KNL,X86] Enable memtest
c64df707
YL
1267 Format: <integer>
1268 range: 0,4 : pattern number
1269 default : 0 <disable>
1270
1da177e4
LT
1271 meye.*= [HW] Set MotionEye Camera parameters
1272 See Documentation/video4linux/meye.txt.
1273
8f36881b
AS
1274 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1275 Multi-Function General Purpose Timers on AMD Geode
1276 platforms.
1277
e6c4dc6c
WT
1278 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1279 the BIOS has incorrectly applied a workaround. TinyBIOS
1280 version 0.98 is known to be affected, 0.99 fixes the
1281 problem by letting the user disable the workaround.
1282
1da177e4
LT
1283 mga= [HW,DRM]
1284
6b74ab97
MG
1285 mminit_loglevel=
1286 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1287 parameter allows control of the logging verbosity for
1288 the additional memory initialisation checks. A value
1289 of 0 disables mminit logging and a level of 4 will
1290 log everything. Information is printed at KERN_DEBUG
1291 so loglevel=8 may also need to be specified.
1292
1da177e4
LT
1293 mousedev.tap_time=
1294 [MOUSE] Maximum time between finger touching and
1295 leaving touchpad surface for touch to be considered
1296 a tap and be reported as a left button click (for
1297 touchpads working in absolute mode only).
1298 Format: <msecs>
1299 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1300 reporting absolute coordinates, such as tablets
1301 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1302 reporting absolute coordinates, such as tablets
1303
1304 mpu401= [HW,OSS]
1305 Format: <io>,<irq>
1306
1307 MTD_Partition= [MTD]
1308 Format: <name>,<region-number>,<size>,<offset>
1309
a9913044
RD
1310 MTD_Region= [MTD] Format:
1311 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1312
1313 mtdparts= [MTD]
c8facbb6 1314 See drivers/mtd/cmdlinepart.c.
1da177e4 1315
9db829f4
BD
1316 mtdset= [ARM]
1317 ARM/S3C2412 JIVE boot control
1318
1319 See arch/arm/mach-s3c2412/mach-jive.c
1320
1da177e4 1321 mtouchusb.raw_coordinates=
a9913044
RD
1322 [HW] Make the MicroTouch USB driver use raw coordinates
1323 ('y', default) or cooked coordinates ('n')
1da177e4
LT
1324
1325 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1326
1327 NCR_D700= [HW,SCSI]
1328 See header of drivers/scsi/NCR_D700.c.
1329
1330 ncr5380= [HW,SCSI]
1331
1332 ncr53c400= [HW,SCSI]
1333
1334 ncr53c400a= [HW,SCSI]
1335
1336 ncr53c406a= [HW,SCSI]
1337
1338 ncr53c8xx= [HW,SCSI]
1339
1340 netdev= [NET] Network devices parameters
1341 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1342 Note that mem_start is often overloaded to mean
1343 something different and driver-specific.
a9913044
RD
1344 This usage is only documented in each driver source
1345 file if at all.
1346
58401572
KPO
1347 nf_conntrack.acct=
1348 [NETFILTER] Enable connection tracking flow accounting
1349 0 to disable accounting
1350 1 to enable accounting
1351 Default value depends on CONFIG_NF_CT_ACCT that is
1352 going to be removed in 2.6.29.
1353
1da177e4 1354 nfsaddrs= [NFS]
6ded55da 1355 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
1356
1357 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
6ded55da 1358 See Documentation/filesystems/nfsroot.txt.
1da177e4 1359
a72b4422
TM
1360 nfs.callback_tcpport=
1361 [NFS] set the TCP port on which the NFSv4 callback
1362 channel should listen.
1363
58df095b
TM
1364 nfs.idmap_cache_timeout=
1365 [NFS] set the maximum lifetime for idmapper cache
1366 entries.
1367
f43bf0be
TM
1368 nfs.enable_ino64=
1369 [NFS] enable 64-bit inode numbers.
1370 If zero, the NFS client will fake up a 32-bit inode
1371 number for the readdir() and stat() syscalls instead
1372 of returning the full 64-bit number.
1373 The default is to return 64-bit inode numbers.
1374
e7ba176b
HS
1375 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1376 when a NMI is triggered.
1377 Format: [state][,regs][,debounce][,die]
1378
cd4f0ef7 1379 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1da177e4 1380
cd4f0ef7 1381 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1382 emulation library even if a 387 maths coprocessor
1383 is present.
1384
c1aee215
CL
1385 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1386 caches in the slab allocator. Saves per-node memory,
1387 but will impact performance.
3395ee05 1388
a9913044
RD
1389 noalign [KNL,ARM]
1390
1da177e4
LT
1391 noapic [SMP,APIC] Tells the kernel to not make use of any
1392 IOAPICs that may be present in the system.
1393
1da177e4
LT
1394 nobats [PPC] Do not use BATs for mapping kernel lowmem
1395 on "Classic" PPC cores.
1396
1397 nocache [ARM]
a9913044 1398
163ecdff
SN
1399 nodelayacct [KNL] Disable per-task delay accounting
1400
1da177e4
LT
1401 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1402
6902aa84
PM
1403 nodsp [SH] Disable hardware DSP at boot time.
1404
8b2cb7a8
HY
1405 noefi [X86-32,X86-64] Disable EFI runtime services support.
1406
1da177e4
LT
1407 noexec [IA-64]
1408
cd4f0ef7 1409 noexec [X86-32,X86-64]
f5a1b191 1410 On X86-32 available only on PAE configured kernels.
1da177e4 1411 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1412 noexec=off: disable non-executable mappings
1413
1414 noexec32 [X86-64]
1415 This affects only 32-bit executables.
1416 noexec32=on: enable non-executable mappings (default)
1417 read doesn't imply executable mappings
1418 noexec32=off: disable non-executable mappings
1419 read implies executable mappings
1da177e4 1420
6902aa84
PM
1421 nofpu [SH] Disable hardware FPU at boot time.
1422
cd4f0ef7 1423 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1424 register save and restore. The kernel will only save
1425 legacy floating-point registers on task switch.
1da177e4 1426
191679fd
AK
1427 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1428
6902aa84 1429 nohlt [BUGS=ARM,SH]
a9913044 1430
cd4f0ef7 1431 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1432 instruction doesn't work correctly and not to
1433 use it.
1434
1435 nohalt [IA-64] Tells the kernel not to use the power saving
1436 function PAL_HALT_LIGHT when idle. This increases
1437 power-consumption. On the positive side, it reduces
1438 interrupt wake-up latency, which may improve performance
1439 in certain environments such as networked servers or
1440 real-time systems.
1441
79bf2bb3
TG
1442 nohz= [KNL] Boottime enable/disable dynamic ticks
1443 Valid arguments: on, off
1444 Default: on
1445
cd4f0ef7 1446 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
8542b200 1447
cd4f0ef7 1448 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1449 disable unhandled interrupt sources.
1450
cd4f0ef7 1451 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
8542b200
ZA
1452 broken timer IRQ sources.
1453
1da177e4
LT
1454 noisapnp [ISAPNP] Disables ISA PnP code.
1455
1456 noinitrd [RAM] Tells the kernel not to load any configured
1457 initial RAM disk.
1458
1459 nointroute [IA-64]
1460
0aa366f3
TL
1461 nojitter [IA64] Disables jitter checking for ITC timers.
1462
cd4f0ef7 1463 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1464
cd4f0ef7 1465 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1466
6e1cb38a
SS
1467 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1468
af9d1388
SS
1469 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1470 default x2apic cluster mode on platforms
1471 supporting x2apic.
1472
1da177e4
LT
1473 noltlbs [PPC] Do not use large page/tlb entries for kernel
1474 lowmem mapping on PPC40x.
1475
312f1f01
H
1476 nomca [IA-64] Disable machine check abort handling
1477
cd4f0ef7 1478 nomce [X86-32] Machine Check Exception
abe37e5a 1479
83d7384f
AS
1480 nomfgpt [X86-32] Disable Multi-Function General Purpose
1481 Timer usage (for AMD Geode machines).
1482
cd4f0ef7 1483 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1484
cd4f0ef7 1485 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1486 with UP alternatives
1487
1da177e4
LT
1488 noresidual [PPC] Don't use residual data on PReP machines.
1489
a9913044
RD
1490 noresume [SWSUSP] Disables resume and restores original swap
1491 space.
1492
1da177e4
LT
1493 no-scroll [VGA] Disables scrollback.
1494 This is required for the Braillex ib80-piezo Braille
1495 reader made by F.H. Papenmeier (Germany).
1496
1497 nosbagart [IA-64]
1498
cd4f0ef7 1499 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1500
61ec7567
LB
1501 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1502 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1503
97842216
DJ
1504 nosoftlockup [KNL] Disable the soft-lockup detector.
1505
1da177e4
LT
1506 nosync [HW,M68K] Disables sync negotiation for all devices.
1507
cd4f0ef7 1508 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1509
1510 nousb [USB] Disable the USB subsystem
1511
1512 nowb [ARM]
a9913044 1513
a6c75b86
FY
1514 nptcg= [IA64] Override max number of concurrent global TLB
1515 purges which is reported from either PAL_VM_SUMMARY or
1516 SAL PALO.
1517
f0c0b2b8
KH
1518 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1519 one of ['zone', 'node', 'default'] can be specified
1520 This can be set from sysctl after boot.
1521 See Documentation/sysctl/vm.txt for details.
1522
a61c2d78
DJ
1523 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1524
3ef0e1f8
AS
1525 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1526 Rather than timing out after 20 ms if an EC
1527 command is not properly ACKed, override the length
1528 of the timeout. We have interrupts disabled while
1529 waiting for the ACK, so if this is set too high
1530 interrupts *may* be lost!
1531
1da177e4
LT
1532 opl3= [HW,OSS]
1533 Format: <io>
1534
1da177e4
LT
1535 oprofile.timer= [HW]
1536 Use timer interrupt instead of performance counters
1537
1da177e4
LT
1538 osst= [HW,SCSI] SCSI Tape Driver
1539 Format: <buffer_size>,<write_threshold>
1540 See also Documentation/scsi/st.txt.
1541
1542 panic= [KNL] Kernel behaviour on panic
1543 Format: <timeout>
1544
1545 parkbd.port= [HW] Parallel port number the keyboard adapter is
1546 connected to, default is 0.
1547 Format: <parport#>
1548 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1549 0 for XT, 1 for AT (default is AT).
a9913044
RD
1550 Format: <mode>
1551
1552 parport= [HW,PPT] Specify parallel ports. 0 disables.
1553 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1554 Use 'auto' to force the driver to use any
1555 IRQ/DMA settings detected (the default is to
1556 ignore detected IRQ/DMA settings because of
1557 possible conflicts). You can specify the base
1558 address, IRQ, and DMA settings; IRQ and DMA
1559 should be numbers, or 'auto' (for using detected
1560 settings on that particular port), or 'nofifo'
1561 (to avoid using a FIFO even if it is detected).
1562 Parallel ports are assigned in the order they
1563 are specified on the command line, starting
1564 with parport0.
1565
1566 parport_init_mode= [HW,PPT]
1567 Configure VIA parallel port to operate in
1568 a specific mode. This is necessary on Pegasos
1569 computer where firmware has no options for setting
1570 up parallel port mode and sets it to spp.
1571 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1572 Format: [spp|ps2|epp|ecp|ecpepp]
1573
a9913044
RD
1574 pas2= [HW,OSS] Format:
1575 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1576
1da177e4
LT
1577 pas16= [HW,SCSI]
1578 See header of drivers/scsi/pas16.c.
1579
dd287796
AM
1580 pause_on_oops=
1581 Halt all CPUs after the first oops has been printed for
1582 the specified number of seconds. This is to be used if
1583 your oopses keep scrolling off the screen.
1584
1da177e4
LT
1585 pcbit= [HW,ISDN]
1586
1587 pcd. [PARIDE]
1588 See header of drivers/block/paride/pcd.c.
1589 See also Documentation/paride.txt.
1590
a9913044 1591 pci=option[,option...] [PCI] various PCI subsystem options:
c0115606 1592 off [X86] don't probe for the PCI bus
cd4f0ef7 1593 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1594 the hardware directly. Use this if your machine
1595 has a non-standard PCI host bridge.
cd4f0ef7 1596 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1597 hardware access methods are allowed. Use this
1598 if you experience crashes upon bootup and you
1599 suspect they are caused by the BIOS.
c0115606 1600 conf1 [X86] Force use of PCI Configuration
a9913044 1601 Mechanism 1.
c0115606 1602 conf2 [X86] Force use of PCI Configuration
a9913044 1603 Mechanism 2.
7f785763
RD
1604 noaer [PCIE] If the PCIEAER kernel config parameter is
1605 enabled, this kernel boot option can be used to
1606 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1607 nodomains [PCI] Disable support for multiple PCI
1608 root domains (aka PCI segments, in ACPI-speak).
cd4f0ef7 1609 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
61be6d66 1610 Configuration
309e57df
MW
1611 nomsi [MSI] If the PCI_MSI kernel config parameter is
1612 enabled, this kernel boot option can be used to
1613 disable the use of MSI interrupts system-wide.
cd4f0ef7 1614 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1615 routing table. These calls are known to be buggy
1616 on several machines and they hang the machine
1617 when used, but on other computers it's the only
1618 way to get the interrupt routing table. Try
1619 this option if the kernel is unable to allocate
1620 IRQs or discover secondary PCI buses on your
1621 motherboard.
c0115606 1622 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1623 Use with caution as certain devices share
1624 address decoders between ROMs and other
1625 resources.
c0115606 1626 norom [X86] Do not assign address space to
bb71ad88
GH
1627 expansion ROMs that do not already have
1628 BIOS assigned address ranges.
c0115606 1629 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1630 assigned automatically to PCI devices. You can
1631 make the kernel exclude IRQs of your ISA cards
1632 this way.
c0115606 1633 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1634 of the PIRQ table (normally generated
1635 by the BIOS) if it is outside the
1636 F0000h-100000h range.
c0115606 1637 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1638 useful if the kernel is unable to find your
1639 secondary buses and you want to tell it
1640 explicitly which ones they are.
c0115606 1641 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1642 numbers ourselves, overriding
1643 whatever the firmware may have done.
c0115606 1644 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1645 in the BIOS $PIR table. This is needed on
1646 some systems with broken BIOSes, notably
1647 some HP Pavilion N5400 and Omnibook XE3
1648 notebooks. This will have no effect if ACPI
1649 IRQ routing is enabled.
c0115606 1650 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1651 or for PCI scanning.
c0115606 1652 use_crs [X86] Use _CRS for PCI resource
62f420f8 1653 allocation.
a9913044
RD
1654 routeirq Do IRQ routing for all PCI devices.
1655 This is normally done in pci_enable_device(),
1656 so this option is a temporary workaround
1657 for broken drivers that don't call it.
13a6ddb0
YL
1658 skip_isa_align [X86] do not align io start addr, so can
1659 handle more pci cards
a9913044
RD
1660 firmware [ARM] Do not re-enumerate the bus but instead
1661 just use the configuration from the
1662 bootloader. This is currently used on
1663 IXP2000 systems where the bus has to be
1664 configured a certain way for adjunct CPUs.
0637a70a
AK
1665 noearly [X86] Don't do any early type 1 scanning.
1666 This might help on some broken boards which
1667 machine check when some devices' config space
1668 is read. But various workarounds are disabled
1669 and some IOMMU drivers will not work.
6b4b78fe
MD
1670 bfsort Sort PCI devices into breadth-first order.
1671 This sorting is done to get a device
1672 order compatible with older (<= 2.4) kernels.
1673 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1674 cbiosize=nn[KMG] The fixed amount of bus space which is
1675 reserved for the CardBus bridge's IO window.
1676 The default value is 256 bytes.
1677 cbmemsize=nn[KMG] The fixed amount of bus space which is
1678 reserved for the CardBus bridge's memory
1679 window. The default value is 64 megabytes.
6b4b78fe 1680
e5665a45
CE
1681 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1682 Management.
1683 off Disable ASPM.
1684 force Enable ASPM even on devices that claim not to support it.
1685 WARNING: Forcing ASPM on may cause system lockups.
1686
1da177e4
LT
1687 pcmv= [HW,PCMCIA] BadgePAD 4
1688
1689 pd. [PARIDE]
1690 See Documentation/paride.txt.
1691
1692 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1693 boot time.
1694 Format: { 0 | 1 }
1695 See arch/parisc/kernel/pdc_chassis.c
1696
1697 pf. [PARIDE]
1698 See Documentation/paride.txt.
1699
1700 pg. [PARIDE]
1701 See Documentation/paride.txt.
1702
1703 pirq= [SMP,APIC] Manual mp-table setup
1704 See Documentation/i386/IO-APIC.txt.
1705
1706 plip= [PPT,NET] Parallel port network link
1707 Format: { parport<nr> | timid | 0 }
1708 See also Documentation/parport.txt.
1709
de32a243
TG
1710 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1711 Override pmtimer IOPort with a hex value.
1712 e.g. pmtmr=0x508
1713
1da177e4
LT
1714 pnpacpi= [ACPI]
1715 { off }
1716
1717 pnpbios= [ISAPNP]
1718 { on | off | curr | res | no-curr | no-res }
1719
1720 pnp_reserve_irq=
1721 [ISAPNP] Exclude IRQs for the autoconfiguration
1722
1723 pnp_reserve_dma=
1724 [ISAPNP] Exclude DMAs for the autoconfiguration
1725
1726 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1727 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1728
1729 pnp_reserve_mem=
a9913044
RD
1730 [ISAPNP] Exclude memory regions for the
1731 autoconfiguration.
1da177e4
LT
1732 Ranges are in pairs (memory base and size).
1733
346e15be
JB
1734 dynamic_printk
1735 Enables pr_debug()/dev_dbg() calls if
1736 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1737 be switched on/off via <debugfs>/dynamic_printk/modules
1738
45807a1d
IM
1739 print-fatal-signals=
1740 [KNL] debug: print fatal signals
1741 print-fatal-signals=1: print segfault info to
1742 the kernel console.
1743 default: off.
1744
e84845c4
RD
1745 printk.time= Show timing data prefixed to each printk message line
1746 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1747
1da177e4 1748 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1749 Format: [schedule,]<number>
1750 Param: "schedule" - profile schedule points.
1751 Param: <number> - step/bucket size as a power of 2 for
1752 statistical time based profiling.
b3da2a73
MG
1753 Param: "sleep" - profile D-state sleeping (millisecs).
1754 Requires CONFIG_SCHEDSTATS
c0fe2e69 1755 Param: "kvm" - profile VM exits.
1da177e4 1756
a9913044 1757 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1758 Limit processor to maximum C-state
1759 max_cstate=9 overrides any DMI blacklist limit.
1760
41c0d868
LB
1761 processor.nocst [HW,ACPI]
1762 Ignore the _CST method to determine C-states,
1763 instead using the legacy FADT method
1764
1da177e4
LT
1765 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1766 before loading.
1767 See Documentation/ramdisk.txt.
1768
a9913044
RD
1769 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1770 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1771 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1772 per second.
a9913044
RD
1773 psmouse.resetafter= [HW,MOUSE]
1774 Try to reset the device after so many bad packets
1da177e4
LT
1775 (0 = never).
1776 psmouse.resolution=
1777 [HW,MOUSE] Set desired mouse resolution, in dpi.
1778 psmouse.smartscroll=
a9913044 1779 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1780 0 = disabled, 1 = enabled (default).
1781
1782 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1783 Format:
1784 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1785
1786 pt. [PARIDE]
1787 See Documentation/paride.txt.
1788
dc8c8587
KS
1789 pty.legacy_count=
1790 [KNL] Number of legacy pty's. Overwrites compiled-in
1791 default number.
1792
7d2c502f 1793 quiet [KNL] Disable most log messages
a9913044 1794
1da177e4
LT
1795 r128= [HW,DRM]
1796
1797 raid= [HW,RAID]
1798 See Documentation/md.txt.
1799
a9913044 1800 ramdisk_blocksize= [RAM]
1da177e4 1801 See Documentation/ramdisk.txt.
a9913044 1802
1da177e4 1803 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1da177e4
LT
1804 See Documentation/ramdisk.txt.
1805
24aaef8d
RD
1806 rcupdate.blimit= [KNL,BOOT]
1807 Set maximum number of finished RCU callbacks to process
1808 in one batch.
21a1ea9e 1809
24aaef8d
RD
1810 rcupdate.qhimark= [KNL,BOOT]
1811 Set threshold of queued
21a1ea9e
DS
1812 RCU callbacks over which batch limiting is disabled.
1813
24aaef8d
RD
1814 rcupdate.qlowmark= [KNL,BOOT]
1815 Set threshold of queued RCU callbacks below which
1816 batch limiting is re-enabled.
21a1ea9e 1817
ffdfc409
OJ
1818 rdinit= [KNL]
1819 Format: <full_path>
1820 Run specified binary instead of /init from the ramdisk,
1821 used for early userspace startup. See initrd.
1822
cd4f0ef7 1823 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1824 Format: <reboot_mode>[,<reboot_mode2>[,...]]
e53dd083 1825 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 1826
46b6d94e
PJ
1827 relax_domain_level=
1828 [KNL, SMP] Set scheduler's default relax_domain_level.
1829 See Documentation/cpusets.txt.
1830
1da177e4
LT
1831 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1832
cd4f0ef7 1833 reservetop= [X86-32]
461a9aff
ZA
1834 Format: nn[KMG]
1835 Reserves a hole at the top of the kernel virtual
1836 address space.
1837
7e96287d
VG
1838 reset_devices [KNL] Force drivers to reset the underlying device
1839 during initialization.
1840
a9913044
RD
1841 resume= [SWSUSP]
1842 Specify the partition device for software suspend
1da177e4 1843
ecbd0da1
RW
1844 resume_offset= [SWSUSP]
1845 Specify the offset from the beginning of the partition
1846 given by "resume=" at which the swap header is located,
1847 in <PAGE_SIZE> units (needed only for swap files).
1848 See Documentation/power/swsusp-and-swap-files.txt
1849
0a7b35cb
MN
1850 retain_initrd [RAM] Keep initrd memory after extraction
1851
1da177e4
LT
1852 rhash_entries= [KNL,NET]
1853 Set number of hash buckets for route cache
1854
1855 riscom8= [HW,SERIAL]
1856 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1857
1858 ro [KNL] Mount root device read-only on boot
1859
1860 root= [KNL] Root filesystem
1861
1862 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1863 mount the root filesystem
1864
1865 rootflags= [KNL] Set root filesystem mount option string
1866
1867 rootfstype= [KNL] Set root filesystem type
1868
cc1ed754
PO
1869 rootwait [KNL] Wait (indefinitely) for root device to show up.
1870 Useful for devices that are detected asynchronously
1871 (e.g. USB and MMC devices).
1872
20510f2f
JM
1873 root_plug.vendor_id=
1874 [ROOTPLUG] Override the default vendor ID
1875
1876 root_plug.product_id=
1877 [ROOTPLUG] Override the default product ID
1878
1879 root_plug.debug=
1880 [ROOTPLUG] Enable debugging output
1881
1da177e4
LT
1882 rw [KNL] Mount root device read-write on boot
1883
1884 S [KNL] Run init in single mode
1885
1886 sa1100ir [NET]
1887 See drivers/net/irda/sa1100_ir.c.
1888
1da177e4 1889 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1890
1da177e4
LT
1891 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1892 Format: <io>[,<timeout>[,<isapnp>]]
1893
1894 scsi_debug_*= [SCSI]
1895 See drivers/scsi/scsi_debug.c.
1896
1897 scsi_default_dev_flags=
1898 [SCSI] SCSI default device flags
1899 Format: <integer>
1900
1901 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1902 Format: <vendor>:<model>:<flags>
1903 (flags are integer value)
1904
6af6632a
RD
1905 scsi_logging_level= [SCSI] a bit mask of logging levels
1906 See drivers/scsi/scsi_logging.h for bits. Also
1907 settable via sysctl at dev.scsi.logging_level
1908 (/proc/sys/dev/scsi/logging_level).
1909 There is also a nice 'scsi_logging_level' script in the
1910 S390-tools package, available for download at
1911 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 1912
3e082a91
MW
1913 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1914 discovered. async scans them in kernel threads,
1915 allowing boot to proceed. none ignores them, expecting
1916 user space to do the scan.
1917
1da177e4
LT
1918 selinux [SELINUX] Disable or enable SELinux at boot time.
1919 Format: { "0" | "1" }
1920 See security/selinux/Kconfig help text.
1921 0 -- disable.
1922 1 -- enable.
1923 Default value is set via kernel config option.
1924 If enabled at boot time, /selinux/disable can be used
1925 later to disable prior to initial policy load.
1926
4e5ab4cb
JM
1927 selinux_compat_net =
1928 [SELINUX] Set initial selinux_compat_net flag value.
e53dd083
MCC
1929 Format: { "0" | "1" }
1930 0 -- use new secmark-based packet controls
1931 1 -- use legacy packet controls
1932 Default value is 0 (preferred).
1933 Value can be changed at runtime via
1934 /selinux/compat_net.
4e5ab4cb 1935
cd4f0ef7 1936 serialnumber [BUGS=X86-32]
1da177e4 1937
1da177e4
LT
1938 shapers= [NET]
1939 Maximal number of shapers.
a9913044 1940
b05f78f5
YL
1941 show_msr= [x86] show boot-time MSR settings
1942 Format: { <integer> }
1943 Show boot-time (BIOS-initialized) MSR settings.
1944 The parameter means the number of CPUs to show,
1945 for example 1 means boot CPU only.
1946
1da177e4
LT
1947 sim710= [SCSI,HW]
1948 See header of drivers/scsi/sim710.c.
1949
1950 simeth= [IA-64]
1951 simscsi=
a9913044 1952
1da177e4
LT
1953 slram= [HW,MTD]
1954
f0630fff
CL
1955 slub_debug[=options[,slabs]] [MM, SLUB]
1956 Enabling slub_debug allows one to determine the
1957 culprit if slab objects become corrupted. Enabling
1958 slub_debug can create guard zones around objects and
1959 may poison objects when not in use. Also tracks the
1960 last alloc / free. For more information see
1961 Documentation/vm/slub.txt.
c1aee215
CL
1962
1963 slub_max_order= [MM, SLUB]
f0630fff
CL
1964 Determines the maximum allowed order for slabs.
1965 A high setting may cause OOMs due to memory
1966 fragmentation. For more information see
1967 Documentation/vm/slub.txt.
c1aee215
CL
1968
1969 slub_min_objects= [MM, SLUB]
f0630fff
CL
1970 The minimum number of objects per slab. SLUB will
1971 increase the slab order up to slub_max_order to
1972 generate a sufficiently large slab able to contain
1973 the number of objects indicated. The higher the number
1974 of objects the smaller the overhead of tracking slabs
1975 and the less frequently locks need to be acquired.
c1aee215
CL
1976 For more information see Documentation/vm/slub.txt.
1977
1978 slub_min_order= [MM, SLUB]
1979 Determines the mininum page order for slabs. Must be
f0630fff 1980 lower than slub_max_order.
c1aee215
CL
1981 For more information see Documentation/vm/slub.txt.
1982
1983 slub_nomerge [MM, SLUB]
f0630fff 1984 Disable merging of slabs with similar size. May be
c1aee215 1985 necessary if there is some reason to distinguish
f0630fff
CL
1986 allocs to different slabs. Debug options disable
1987 merging on their own.
c1aee215
CL
1988 For more information see Documentation/vm/slub.txt.
1989
1da177e4
LT
1990 smart2= [HW]
1991 Format: <io1>[,<io2>[,...,<io8>]]
1992
cd4f0ef7 1993 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
1994 attempt to substitute SMP alternatives once at boot.
1995
d0d4f69b
BH
1996 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1997 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1998 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1999 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2000 smsc-ircc2.ircc_irq= [HW] IRQ line
2001 smsc-ircc2.ircc_dma= [HW] DMA channel
2002 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2003 0: Toshiba Satellite 1800 (GP data pin select)
2004 1: Fast pin select (default)
2005 2: ATC IRMode
2006
1da177e4
LT
2007 snd-ad1816a= [HW,ALSA]
2008
2009 snd-ad1848= [HW,ALSA]
2010
2011 snd-ali5451= [HW,ALSA]
2012
2013 snd-als100= [HW,ALSA]
2014
2015 snd-als4000= [HW,ALSA]
2016
2017 snd-azt2320= [HW,ALSA]
2018
2019 snd-cmi8330= [HW,ALSA]
2020
2021 snd-cmipci= [HW,ALSA]
2022
2023 snd-cs4231= [HW,ALSA]
2024
2025 snd-cs4232= [HW,ALSA]
2026
2027 snd-cs4236= [HW,ALSA]
2028
2029 snd-cs4281= [HW,ALSA]
2030
2031 snd-cs46xx= [HW,ALSA]
2032
2033 snd-dt019x= [HW,ALSA]
2034
2035 snd-dummy= [HW,ALSA]
2036
2037 snd-emu10k1= [HW,ALSA]
2038
2039 snd-ens1370= [HW,ALSA]
2040
2041 snd-ens1371= [HW,ALSA]
2042
2043 snd-es968= [HW,ALSA]
2044
2045 snd-es1688= [HW,ALSA]
2046
2047 snd-es18xx= [HW,ALSA]
2048
2049 snd-es1938= [HW,ALSA]
2050
2051 snd-es1968= [HW,ALSA]
2052
2053 snd-fm801= [HW,ALSA]
2054
2055 snd-gusclassic= [HW,ALSA]
2056
2057 snd-gusextreme= [HW,ALSA]
2058
2059 snd-gusmax= [HW,ALSA]
2060
2061 snd-hdsp= [HW,ALSA]
2062
2063 snd-ice1712= [HW,ALSA]
2064
2065 snd-intel8x0= [HW,ALSA]
2066
2067 snd-interwave= [HW,ALSA]
2068
2069 snd-interwave-stb=
2070 [HW,ALSA]
2071
2072 snd-korg1212= [HW,ALSA]
2073
2074 snd-maestro3= [HW,ALSA]
2075
2076 snd-mpu401= [HW,ALSA]
2077
2078 snd-mtpav= [HW,ALSA]
2079
2080 snd-nm256= [HW,ALSA]
2081
2082 snd-opl3sa2= [HW,ALSA]
2083
2084 snd-opti92x-ad1848=
2085 [HW,ALSA]
2086
2087 snd-opti92x-cs4231=
2088 [HW,ALSA]
2089
2090 snd-opti93x= [HW,ALSA]
2091
2092 snd-pmac= [HW,ALSA]
2093
2094 snd-rme32= [HW,ALSA]
2095
2096 snd-rme96= [HW,ALSA]
2097
2098 snd-rme9652= [HW,ALSA]
2099
2100 snd-sb8= [HW,ALSA]
2101
2102 snd-sb16= [HW,ALSA]
2103
2104 snd-sbawe= [HW,ALSA]
2105
2106 snd-serial= [HW,ALSA]
2107
2108 snd-sgalaxy= [HW,ALSA]
2109
2110 snd-sonicvibes= [HW,ALSA]
2111
2112 snd-sun-amd7930=
2113 [HW,ALSA]
2114
2115 snd-sun-cs4231= [HW,ALSA]
2116
2117 snd-trident= [HW,ALSA]
2118
2119 snd-usb-audio= [HW,ALSA,USB]
2120
2121 snd-via82xx= [HW,ALSA]
2122
2123 snd-virmidi= [HW,ALSA]
2124
2125 snd-wavefront= [HW,ALSA]
2126
2127 snd-ymfpci= [HW,ALSA]
a9913044 2128
9c44bc03
IM
2129 softlockup_panic=
2130 [KNL] Should the soft-lockup detector generate panics.
2131
1da177e4
LT
2132 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2133 See Documentation/sonypi.txt
2134
2135 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2136 See Documentation/specialix.txt.
2137
2138 spia_io_base= [HW,MTD]
2139 spia_fio_base=
2140 spia_pedr=
2141 spia_peddr=
2142
2143 sscape= [HW,OSS]
2144 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2145
1da177e4
LT
2146 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2147 See Documentation/scsi/st.txt.
2148
1da177e4
LT
2149 sti= [PARISC,HW]
2150 Format: <num>
2151 Set the STI (builtin display/keyboard on the HP-PARISC
2152 machines) console (graphic card) which should be used
2153 as the initial boot-console.
2154 See also comment in drivers/video/console/sticore.c.
2155
2156 sti_font= [HW]
2157 See comment in drivers/video/console/sticore.c.
2158
2159 stifb= [HW]
2160 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2161
42a7fc4a
GB
2162 sunrpc.pool_mode=
2163 [NFS]
2164 Control how the NFS server code allocates CPUs to
2165 service thread pools. Depending on how many NICs
2166 you have and where their interrupts are bound, this
2167 option will affect which CPUs will do NFS serving.
2168 Note: this parameter cannot be changed while the
2169 NFS server is running.
2170
2171 auto the server chooses an appropriate mode
2172 automatically using heuristics
2173 global a single global pool contains all CPUs
2174 percpu one pool for each CPU
2175 pernode one pool for each NUMA node (equivalent
2176 to global on non-NUMA machines)
2177
1da177e4 2178 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2179
1da177e4
LT
2180 switches= [HW,M68k]
2181
2182 sym53c416= [HW,SCSI]
2183 See header of drivers/scsi/sym53c416.c.
2184
5d6f647f
IM
2185 sysrq_always_enabled
2186 [KNL]
2187 Ignore sysrq setting - this boot parameter will
2188 neutralize any effect of /proc/sys/kernel/sysrq.
2189 Useful for debugging.
2190
1da177e4
LT
2191 t128= [HW,SCSI]
2192 See header of drivers/scsi/t128.c.
2193
2194 tdfx= [HW,DRM]
2195
77437fd4
DB
2196 test_suspend= [SUSPEND]
2197 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2198 standby suspend) as the system sleep state to briefly
2199 enter during system startup. The system is woken from
2200 this state using a wakeup-capable RTC alarm.
2201
1da177e4
LT
2202 thash_entries= [KNL,NET]
2203 Set number of hash buckets for TCP connection
2204
f8707ec9
LB
2205 thermal.act= [HW,ACPI]
2206 -1: disable all active trip points in all thermal zones
2207 <degrees C>: override all lowest active trip points
2208
c52a7419
LB
2209 thermal.crt= [HW,ACPI]
2210 -1: disable all critical trip points in all thermal zones
2211 <degrees C>: lower all critical trip points
2212
f5487145
LB
2213 thermal.nocrt= [HW,ACPI]
2214 Set to disable actions on ACPI thermal zone
2215 critical and hot trip points.
2216
72b33ef8
LB
2217 thermal.off= [HW,ACPI]
2218 1: disable ACPI thermal control
2219
a70cdc52
LB
2220 thermal.psv= [HW,ACPI]
2221 -1: disable all passive trip points
2222 <degrees C>: override all passive trip points to this value
2223
730ff34d
LB
2224 thermal.tzp= [HW,ACPI]
2225 Specify global default ACPI thermal zone polling rate
2226 <deci-seconds>: poll all this frequency
2227 0: no polling (default)
2228
1da177e4
LT
2229 tmscsim= [HW,SCSI]
2230 See comment before function dc390_setup() in
2231 drivers/scsi/tmscsim.c.
2232
2233 tp720= [HW,PS2]
2234
2235 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2236 Format:
2237 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2238
a9913044
RD
2239 turbografx.map[2|3]= [HW,JOY]
2240 TurboGraFX parallel port interface
2241 Format:
2242 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2243 See also Documentation/input/joystick-parport.txt
2244
2245 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2246 See header of drivers/scsi/u14-34f.c.
2247
2248 uart401= [HW,OSS]
2249 Format: <io>,<irq>
2250
2251 uart6850= [HW,OSS]
2252 Format: <io>,<irq>
2253
5f8364b7
AS
2254 uhci-hcd.ignore_oc=
2255 [USB] Ignore overcurrent events (default N).
2256 Some badly-designed motherboards generate lots of
2257 bogus events, for ports that aren't wired to
2258 anything. Set this parameter to avoid log spamming.
2259 Note that genuine overcurrent events won't be
2260 reported either.
2261
e3a61b0a
SA
2262 unknown_nmi_panic
2263 [X86-32,X86-64]
2264 Set unknown_nmi_panic=1 early on boot.
2265
b5e795f8
AS
2266 usbcore.autosuspend=
2267 [USB] The autosuspend time delay (in seconds) used
2268 for newly-detected USB devices (default 2). This
2269 is the time required before an idle device will be
2270 autosuspended. Devices for which the delay is set
eaafbc3a 2271 to a negative value won't be autosuspended at all.
b5e795f8 2272
fd7c519d
JK
2273 usbcore.usbfs_snoop=
2274 [USB] Set to log all usbfs traffic (default 0 = off).
2275
2276 usbcore.blinkenlights=
2277 [USB] Set to cycle leds on hubs (default 0 = off).
2278
2279 usbcore.old_scheme_first=
2280 [USB] Start with the old device initialization
2281 scheme (default 0 = off).
2282
2283 usbcore.use_both_schemes=
2284 [USB] Try the other device initialization scheme
2285 if the first one fails (default 1 = enabled).
2286
2287 usbcore.initial_descriptor_timeout=
2288 [USB] Specifies timeout for the initial 64-byte
2289 USB_REQ_GET_DESCRIPTOR request in milliseconds
2290 (default 5000 = 5.0 seconds).
2291
1da177e4
LT
2292 usbhid.mousepoll=
2293 [USBHID] The interval which mice are to be polled at.
a9913044 2294
200001eb
PJ
2295 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2296 kernel's map of available physical RAM.
2297
cd4f0ef7 2298 vdso= [X86-32,SH,x86-64]
1dbf527c 2299 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2300 vdso=1: enable VDSO (default)
2301 vdso=0: disable VDSO mapping
2302
af65d648
RM
2303 vdso32= [X86-32,X86-64]
2304 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2305 vdso32=1: enable 32-bit VDSO (default)
2306 vdso32=0: disable 32-bit VDSO mapping
2307
d080d397
YI
2308 vector= [IA-64,SMP]
2309 vector=percpu: enable percpu vector domain
2310
1da177e4
LT
2311 video= [FB] Frame buffer configuration
2312 See Documentation/fb/modedb.txt.
2313
cd4f0ef7 2314 vga= [BOOT,X86-32] Select a particular video mode
a9913044
RD
2315 See Documentation/i386/boot.txt and
2316 Documentation/svga.txt.
1da177e4
LT
2317 Use vga=ask for menu.
2318 This is actually a boot loader parameter; the value is
2319 passed to the kernel using a special protocol.
2320
a9913044 2321 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2322 size of <nn>. This can be used to increase the
2323 minimum size (128MB on x86). It can also be used to
2324 decrease the size and leave more room for directly
2325 mapped kernel RAM.
2326
585c3047
PO
2327 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2328 Format: <command>
1da177e4 2329
585c3047
PO
2330 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2331 Format: <command>
2332
2333 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2334 Format: <command>
a9913044 2335
1da177e4
LT
2336 waveartist= [HW,OSS]
2337 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2338
1da177e4
LT
2339 wd33c93= [HW,SCSI]
2340 See header of drivers/scsi/wd33c93.c.
2341
2342 wd7000= [HW,SCSI]
2343 See header of drivers/scsi/wd7000.c.
2344
2345 wdt= [WDT] Watchdog
8dfe9c21 2346 See Documentation/watchdog/wdt.txt.
1da177e4
LT
2347
2348 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2349 xd_geo= See header of drivers/block/xd.c.
2350
2351 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2352 Format:
2353 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2354
a62eaf15
AK
2355 norandmaps Don't use address space randomization
2356 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2357
a9913044 2358______________________________________________________________________
1da177e4
LT
2359
2360TODO:
2361
2362 Add documentation for ALSA options.
2363 Add more DRM drivers.