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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
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
Stefan Richtera901ebb2006-04-01 01:43:18 +020020This 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
Stefan Richter6585fa82006-04-01 01:44:30 +020027The 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:
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100033 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020037 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080039 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070040 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070048 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070052 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 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.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070061 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070062 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070065 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070068 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070072 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 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.
James Morris20510f22007-10-16 23:31:32 -070079 ROOTPLUG The example Root Plug LSM is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 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/.
James Morris20510f22007-10-16 23:31:32 -070084 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090087 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -070090 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 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.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700100 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700103 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
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
Uwe Hermann71cced62008-10-20 09:32:21 -0700115need or coordination with <Documentation/x86/i386/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
Karsten Weiss55588702007-02-13 13:26:21 +0100117There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700118See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100119
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120Note 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
jens m. noedler9c4751f2006-09-29 02:00:27 -0700126The 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
Bernhard Walle03d926f2007-03-06 02:29:44 -0800133 acpi= [HW,ACPI,X86-64,i386]
134 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700135 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 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
Randy Dunlapa9913042005-10-23 12:57:11 -0700140 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800142 rsdt -- prefer RSDT over (default) XSDT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
Randy Dunlap53471122008-03-12 18:10:51 -0400144 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
Len Browna1fdcc02007-03-11 03:26:14 -0400146 acpi_apic_instance= [ACPI, IOAPIC]
147 Format: <int>
148 2: use 2nd APIC table, if available
149 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400150 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400151
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 acpi_sleep= [HW,ACPI] Sleep options
Shaohua Libdfe6b72008-07-23 21:28:41 -0700153 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
Pavel Machek23b168d2008-02-05 19:27:12 +0100154 See Documentation/power/video.txt for s3_bios and s3_mode.
155 s3_beep is for debugging; it makes the PC's speaker beep
156 as soon as the kernel's real-mode entry point is called.
Shaohua Libdfe6b72008-07-23 21:28:41 -0700157 s4_nohwsig prevents ACPI hardware signature from being
158 used during resume from hibernation.
Rafael J. Wysockid8f3de02008-06-12 23:24:06 +0200159 old_ordering causes the ACPI 1.0 ordering of the _PTS
160 control method, wrt putting devices into low power
161 states, to be enforced (the ACPI 2.0 ordering of _PTS is
162 used by default).
Randy Dunlapa9913042005-10-23 12:57:11 -0700163
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700165 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
Randy Dunlapa9913042005-10-23 12:57:11 -0700167 acpi_irq_balance [HW,ACPI]
168 ACPI will balance active IRQs
169 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170
Randy Dunlapa9913042005-10-23 12:57:11 -0700171 acpi_irq_nobalance [HW,ACPI]
172 ACPI will not move active IRQs (default)
173 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174
Randy Dunlapa9913042005-10-23 12:57:11 -0700175 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
176 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 Format: <irq>,<irq>...
178
Randy Dunlapa9913042005-10-23 12:57:11 -0700179 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 Format: <irq>,<irq>...
181
Len Brown67effe82007-07-26 00:50:06 -0400182 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
183
Len Browna1f9e652006-01-25 23:47:36 -0500184 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
185 Format: To spoof as Windows 98: ="Microsoft Windows"
186
Len Brownae00d812007-05-29 18:43:33 -0400187 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
188 acpi_osi="string1" # add string1 -- only one string
189 acpi_osi="!string2" # remove built-in string2
190 acpi_osi= # disable all strings
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191
192 acpi_serialize [HW,ACPI] force serialization of AML methods
193
194 acpi_skip_timer_override [HW,ACPI]
195 Recognize and ignore IRQ0/pin2 Interrupt Override.
196 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100197 acpi_use_timer_override [HW,ACPI}
198 Use timer override. For some broken Nvidia NF5 boards
199 that require a timer override, but don't have
200 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200202 acpi_backlight= [HW,ACPI]
203 acpi_backlight=vendor
204 acpi_backlight=video
205 If set to vendor, prefer vendor specific driver
206 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
207 of the ACPI video.ko driver.
208
209 acpi_display_output= [HW,ACPI]
210 acpi_display_output=vendor
211 acpi_display_output=video
212 See above.
213
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700214 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
215 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700217 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
218 debug output. Bits in debug_layer correspond to a
219 _COMPONENT in an ACPI source file, e.g.,
220 #define _COMPONENT ACPI_PCI_COMPONENT
221 Bits in debug_level correspond to a level in
222 ACPI_DEBUG_PRINT statements, e.g.,
223 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600224 The debug_level mask defaults to "info". See
225 Documentation/acpi/debug.txt for more information about
226 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600228 Enable processor driver info messages:
229 acpi.debug_layer=0x20000000
230 Enable PCI/PCI interrupt routing info messages:
231 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700232 Enable AML "Debug" output, i.e., stores to the Debug
233 object while interpreting AML:
234 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700235 Enable all messages related to ACPI hardware:
236 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200237
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700238 Some values produce so much output that the system is
239 unusable. The "log_buf_len" parameter may be useful
240 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800241
Zhao Yakuif5adfaa2008-08-11 14:57:50 +0800242 acpi.power_nocheck= [HW,ACPI]
243 Format: 1/0 enable/disable the check of power state.
244 On some bogus BIOS the _PSC object/_STA object of
245 power resource can't return the correct device power
246 state. In such case it is unneccessary to check its
247 power state again in power transition.
248 1 : disable the power state check
249
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700250 acpi_pm_good [X86-32,X86-64]
john stultz5d0cf412006-06-26 00:25:12 -0700251 Override the pmtimer bug detection: force the kernel
252 to assume that this machine's pmtimer latches its value
253 and always returns good values.
254
Chuck Ebbertc99c1082007-07-27 10:46:20 +1000255 agp= [AGP]
256 { off | try_unsupported }
257 off: disable AGP support
258 try_unsupported: try to drive unsupported chipsets
259 (may crash computer or cause data corruption)
260
Chuck Ebbert66759a02005-09-12 18:49:25 +0200261 enable_timer_pin_1 [i386,x86-64]
262 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700263 Can be useful to work around chipset bugs
264 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200265 The kernel tries to set a reasonable default.
266
267 disable_timer_pin_1 [i386,x86-64]
268 Disable PIN 1 of APIC timer
269 Can be useful to work around chipset bugs.
270
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 ad1848= [HW,OSS]
272 Format: <io>,<irq>,<dma>,<dma2>,<type>
273
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 advansys= [HW,SCSI]
275 See header of drivers/scsi/advansys.c.
276
277 advwdt= [HW,WDT] Advantech WDT
278 Format: <iostart>,<iostop>
279
280 aedsp16= [HW,OSS] Audio Excel DSP 16
281 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
282 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700283
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 aha152x= [HW,SCSI]
285 See Documentation/scsi/aha152x.txt.
286
287 aha1542= [HW,SCSI]
288 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
289
290 aic7xxx= [HW,SCSI]
291 See Documentation/scsi/aic7xxx.txt.
292
293 aic79xx= [HW,SCSI]
294 See Documentation/scsi/aic79xx.txt.
295
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200296 amd_iommu= [HW,X86-84]
297 Pass parameters to the AMD IOMMU driver in the system.
298 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200299 isolate - enable device isolation (each device, as far
300 as possible, will get its own protection
Joerg Roedel3ce1f932008-11-17 15:09:20 +0100301 domain) [default]
Joerg Roedele5e1f602008-11-17 15:07:17 +0100302 share - put every device behind one IOMMU into the
303 same protection domain
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900304 fullflush - enable flushing of IO/TLB entries when
305 they are unmapped. Otherwise they are
306 flushed before they will be reused, which
307 is a lot of faster
308
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200309 amd_iommu_size= [HW,X86-64]
310 Define the size of the aperture for the AMD IOMMU
311 driver. Possible values are:
312 '32M', '64M' (default), '128M', '256M', '512M', '1G'
313
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 amijoy.map= [HW,JOY] Amiga joystick support
315 Map of devices attached to JOY0DAT and JOY1DAT
316 Format: <a>,<b>
317 See also Documentation/kernel/input/joystick.txt
318
319 analog.map= [HW,JOY] Analog joystick and gamepad support
320 Specifies type or capabilities of an analog joystick
321 connected to one of 16 gameports
322 Format: <type1>,<type2>,..<type16>
323
Randy Dunlapa9913042005-10-23 12:57:11 -0700324 apc= [HW,SPARC]
325 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 Format: noidle
327 Disable APC CPU standby support. SPARCstation-Fox does
328 not play well with APC CPU idle - disable it if you have
329 APC and your system crashes randomly.
330
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700331 apic= [APIC,i386] Advanced Programmable Interrupt Controller
332 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 Format: { quiet (default) | verbose | debug }
334 Change the amount of debugging information output
335 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700336
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700338 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
341 Format: <io>,<irq>,<nodeID>
342
343 ataflop= [HW,M68k]
344
345 atarimouse= [HW,MOUSE] Atari Mouse
346
347 atascsi= [HW,SCSI] Atari SCSI
348
349 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
350 EzKey and similar keyboards
351
352 atkbd.reset= [HW] Reset keyboard during initialization
353
Randy Dunlapa9913042005-10-23 12:57:11 -0700354 atkbd.set= [HW] Select keyboard code set
355 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356
357 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
358 keyboards
359
360 atkbd.softraw= [HW] Choose between synthetic and real raw mode
361 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700362
363 atkbd.softrepeat= [HW]
364 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365
366 autotest [IA64]
367
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 baycom_epp= [HW,AX25]
369 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700370
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
372 Format: <io>,<mode>
373 See header of drivers/net/hamradio/baycom_par.c.
374
Randy Dunlapa9913042005-10-23 12:57:11 -0700375 baycom_ser_fdx= [HW,AX25]
376 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 Format: <io>,<irq>,<mode>[,<baud>]
378 See header of drivers/net/hamradio/baycom_ser_fdx.c.
379
Randy Dunlapa9913042005-10-23 12:57:11 -0700380 baycom_ser_hdx= [HW,AX25]
381 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 Format: <io>,<irq>,<mode>
383 See header of drivers/net/hamradio/baycom_ser_hdx.c.
384
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700385 boot_delay= Milliseconds to delay each printk during boot.
386 Values larger than 10 seconds (10000) are changed to
387 no delay (0).
388 Format: integer
389
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700390 bootmem_debug [KNL] Enable bootmem allocator debug messages.
391
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700393 bttv.radio= Most important insmod options are available as
394 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
396 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
397
398 BusLogic= [HW,SCSI]
399 See drivers/scsi/BusLogic.c, comment before function
400 BusLogic_ParseDriverOptions().
401
402 c101= [NET] Moxa C101 synchronous serial card
403
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700404 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 Sometimes CPU hardware bugs make them report the cache
406 size incorrectly. The kernel will attempt work arounds
407 to fix known problems, but for some CPUs it is not
408 possible to determine what the correct size should be.
409 This option provides an override for these situations.
410
Ahmed S. Darwish076c54c2008-03-06 18:09:10 +0200411 security= [SECURITY] Choose a security module to enable at boot.
412 If this boot parameter is not specified, only the first
413 security module asking for security registration will be
414 loaded. An invalid security module name will be treated
415 as if no module has been chosen.
416
James Morris20510f22007-10-16 23:31:32 -0700417 capability.disable=
418 [SECURITY] Disable capabilities. This would normally
419 be used only if an alternative security model is to be
420 configured. Potentially dangerous and should only be
421 used if you are entirely sure of the consequences.
422
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100423 ccw_timeout_log [S390]
424 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425
Paul Menage8bab8dd2008-04-04 14:29:57 -0700426 cgroup_disable= [KNL] Disable a particular controller
427 Format: {name of the controller(s) to disable}
428 {Currently supported controllers - "memory"}
429
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 checkreqprot [SELINUX] Set initial checkreqprot flag value.
431 Format: { "0" | "1" }
432 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700433 0 -- check protection applied by kernel (includes
434 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 1 -- check protection requested by application.
436 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700437 Value can be changed at runtime via
438 /selinux/checkreqprot.
439
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100440 cio_ignore= [S390]
441 See Documentation/s390/CommonIO for details.
442
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700443 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700444 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200445 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700446 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200447 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 Format: { pit | tsc | cyclone | pmtmr }
449
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700450 clocksource= [GENERIC_TIME] Override the default clocksource
451 Format: <string>
452 Override the default clocksource and use the clocksource
453 with the name specified.
454 Some clocksource names to choose from, depending on
455 the platform:
456 [all] jiffies (this is the base, fallback clocksource)
457 [ACPI] acpi_pm
458 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
459 pxa_timer,timer3,32k_counter,timer0_1
460 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700461 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700462 scx200_hrt on Geode; cyclone on IBM x440
463 [MIPS] MIPS
464 [PARISC] cr16
465 [S390] tod
466 [SH] SuperH
467 [SPARC64] tick
468 [X86-64] hpet,tsc
469
Andi Kleenac72e782008-01-30 13:33:21 +0100470 clearcpuid=BITNUM [X86]
471 Disable CPUID feature X for the kernel. See
472 include/asm-x86/cpufeature.h for the valid bit numbers.
473 Note the Linux specific bits are not necessarily
474 stable over kernel options, but the vendor specific
475 ones should be.
476 Also note that user programs calling CPUID directly
477 or using the feature without checking anything
478 will still see it. This just prevents it from
479 being used by the kernel or shown in /proc/cpuinfo.
480 Also note the kernel might malfunction if you disable
481 some critical bits.
482
Arjan van de Vena25bd942008-01-30 13:33:08 +0100483 code_bytes [IA32/X86_64] How many bytes of object code to print
484 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100485 Range: 0 - 8192
486 Default: 64
487
Thomas Gleixnerb17530b2007-10-19 20:35:02 +0200488 hpet= [X86-32,HPET] option to control HPET usage
489 Format: { enable (default) | disable | force }
490 disable: disable HPET and use PIT instead
Carlos Corbachod79a5f82007-10-19 18:51:27 +0100491 force: allow force enabled of undocumented chips (ICH4,
492 VIA, nVidia)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700495 Format:
496 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497
498 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
499 Format: <io>[,<irq>]
500
Randy Dunlapa9913042005-10-23 12:57:11 -0700501 com90xx= [HW,NET]
502 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 Format: <io>[,<irq>[,<memstart>]]
504
505 condev= [HW,S390] console device
506 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700507
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 console= [KNL] Output console device and options.
509
510 tty<n> Use the virtual console device <n>.
511
512 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800513 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800515 the form "bbbbpnf", where "bbbb" is the baud rate,
516 "p" is parity ("n", "o", or "e"), "n" is number of
517 bits, and "f" is flow control ("r" for RTS or
518 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800520 See Documentation/serial-console.txt for more
521 information. See
522 Documentation/networking/netconsole.txt for an
523 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700525 uart[8250],io,<addr>[,options]
526 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 Start an early, polled-mode console on the 8250/16550
528 UART at the specified I/O port or MMIO address,
529 switching to the matching ttyS device later. The
530 options are the same as for ttyS, above.
531
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700532 If the device connected to the port is not a TTY but a braille
533 device, prepend "brl," before the device type, for instance
534 console=brl,ttyS0
535 For now, only VisioBraille is supported.
536
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700537 earlycon= [KNL] Output early console device and options.
538 uart[8250],io,<addr>[,options]
539 uart[8250],mmio,<addr>[,options]
540 Start an early, polled-mode console on the 8250/16550
541 UART at the specified I/O port or MMIO address.
542 The options are the same as for ttyS, above.
543
Andres Salomon8f4ce8c2007-10-18 03:04:50 -0700544 no_console_suspend
545 [HW] Never suspend the console
546 Disable suspending of consoles during suspend and
547 hibernate operations. Once disabled, debugging
548 messages can reach various consoles while the rest
549 of the system is being put to sleep (ie, while
550 debugging driver suspend/resume hooks). This may
551 not work reliably with all consoles, but is known
552 to work with serial and VGA consoles.
553
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700555 Format:
556 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700558 crashkernel=nn[KMG]@ss[KMG]
559 [KNL] Reserve a chunk of physical memory to
560 hold a kernel to switch to with kexec on panic.
561
Bernhard Wallefb391592007-10-18 23:41:02 -0700562 crashkernel=range1:size1[,range2:size2,...][@offset]
563 [KNL] Same as above, but depends on the memory
564 in the running system. The syntax of range is
565 start-[end] where start and end are both
566 a memory unit (amount[KMG]). See also
567 Documentation/kdump/kdump.txt for a example.
568
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 cs4232= [HW,OSS]
570 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
571
572 cs89x0_dma= [HW,NET]
573 Format: <dma>
574
575 cs89x0_media= [HW,NET]
576 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700577
Randy Dunlapa9913042005-10-23 12:57:11 -0700578 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 See header of drivers/s390/block/dasd_devmap.c.
580
581 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
582 (one device per port)
583 Format: <port#>,<type>
584 See also Documentation/input/joystick-parport.txt
585
586 debug [KNL] Enable kernel debugging (events log level).
587
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700588 debug_locks_verbose=
589 [KNL] verbose self-tests
590 Format=<0|1>
591 Print debugging info while doing the locking API
592 self-tests.
593 We default to 0 (no extra messages), setting it to
594 1 will print _a lot_ more information - normally
595 only useful to kernel developers.
596
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700597 debug_objects [KNL] Enable object debugging
598
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200599 debugpat [X86] Enable PAT debugging
600
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200601 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602 Format: <area>[,<node>]
603 See also Documentation/networking/decnet.txt.
604
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000605 vt.default_blu= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700606 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
607 Change the default blue palette of the console.
608 This is a 16-member array composed of values
609 ranging from 0-255.
610
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000611 vt.default_grn= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700612 Format: <green0>,<green1>,<green2>,...,<green15>
613 Change the default green palette of the console.
614 This is a 16-member array composed of values
615 ranging from 0-255.
616
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000617 vt.default_red= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700618 Format: <red0>,<red1>,<red2>,...,<red15>
619 Change the default red palette of the console.
620 This is a 16-member array composed of values
621 ranging from 0-255.
622
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000623 vt.default_utf8=
624 [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700625 Format=<0|1>
626 Set system-wide default UTF-8 mode for all tty's.
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000627 Default is 1, i.e. UTF-8 mode is enabled for all
628 newly opened terminals.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700629
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 dhash_entries= [KNL]
631 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700632
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 digi= [HW,SERIAL]
634 IO parameters + enable/disable command.
635
636 digiepca= [HW,SERIAL]
637 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000638 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639
Yinghai Lu95ffa242008-04-29 03:52:33 -0700640 disable_mtrr_cleanup [X86]
641 enable_mtrr_cleanup [X86]
642 The kernel tries to adjust MTRR layout from continuous
643 to discrete, to make X server driver able to add WB
644 entry later. This parameter enables/disables that.
645
646 mtrr_chunk_size=nn[KMG] [X86]
647 used for mtrr cleanup. It is largest continous chunk
648 that could hold holes aka. UC entries.
649
650 mtrr_gran_size=nn[KMG] [X86]
Yinghai Lu12031a62008-05-02 02:40:22 -0700651 Used for mtrr cleanup. It is granularity of mtrr block.
652 Default is 1.
653 Large value could prevent small alignment from
654 using up MTRRs.
655
656 mtrr_spare_reg_nr=n [X86]
657 Format: <integer>
658 Range: 0,7 : spare reg number
659 Default : 1
660 Used for mtrr cleanup. It is spare mtrr entries number.
661 Set to 2 or more if your graphical card needs more.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700662
Yinghai Lu093af8d2008-01-30 13:33:32 +0100663 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100664 By default the kernel will trim any uncacheable
665 memory out of your available memory pool based on
666 MTRR settings. This parameter disables that behavior,
667 possibly causing your machine to run very slowly.
668
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 dmasound= [HW,OSS] Sound subsystem buffers
670
671 dscc4.setup= [NET]
672
673 dtc3181e= [HW,SCSI]
674
Robin Getz0ae53642007-10-09 17:24:49 +0800675 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 earlyprintk=vga
677 earlyprintk=serial[,ttySn[,baudrate]]
Yinghai Lu5c059172008-07-24 17:29:40 -0700678 earlyprintk=dbgp
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679
Randy Dunlapa9913042005-10-23 12:57:11 -0700680 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 takes over.
682
Yinghai Lu5c059172008-07-24 17:29:40 -0700683 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684
685 Currently only ttyS0 and ttyS1 are supported.
686
687 Interaction with the standard serial driver is not
688 very good.
689
690 The VGA output is eventually overwritten by the real
691 console.
692
693 eata= [HW,SCSI]
694
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700696 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 eisa_irq_edge= [PARISC,HW]
699 See header of drivers/parisc/eisa.c.
700
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700701 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700703 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704
705 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800706 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700707 See Documentation/block/as-iosched.txt and
708 Documentation/block/deadline-iosched.txt for details.
709
Simon Hormane515a0d2008-10-18 20:28:27 -0700710 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700711 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800712 image elf header. Generally kexec loader will
713 pass this option to capture kernel.
714 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715
716 enforcing [SELINUX] Set initial enforcing status.
717 Format: {"0" | "1"}
718 See security/selinux/Kconfig help text.
719 0 -- permissive (log only, no denials).
720 1 -- enforcing (deny and log).
721 Default value is 0.
722 Value can be changed at runtime via /selinux/enforce.
723
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 es1371= [HW,OSS]
725 Format: <spdif>,[<nomix>,[<amplifier>]]
726 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700727
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 ether= [HW,NET] Ethernet cards parameters
729 This option is obsoleted by the "netdev=" option, which
730 has equivalent usage. See its documentation for details.
731
732 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
733 Format: <io>[,<irq>]
734
Akinobu Mitade1ba092006-12-08 02:39:42 -0800735 failslab=
736 fail_page_alloc=
737 fail_make_request=[KNL]
738 General fault injection mechanism.
739 Format: <interval>,<probability>,<space>,<times>
740 See also /Documentation/fault-injection/.
741
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 fd_mcs= [HW,SCSI]
743 See header of drivers/scsi/fd_mcs.c.
744
745 fdomain= [HW,SCSI]
746 See header of drivers/scsi/fdomain.c.
747
748 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000749 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750
Alex Chiangf13ae302008-05-08 14:03:23 -0600751 force_pal_cache_flush
752 [IA-64] Avoid check_sal_cache_flush which may hang on
753 buggy SAL_CACHE_FLUSH implementations. Using this
754 parameter will force ia64_sal_cache_flush to call
755 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
756
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 gamecon.map[2|3]=
758 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
759 support via parallel port (up to 5 devices per port)
760 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
761 See also Documentation/input/joystick-parport.txt
762
763 gamma= [HW,DRM]
764
Yinghai Luaaf23042008-01-30 13:33:09 +0100765 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
766 Format: off | on
767 default: on
768
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 gdth= [HW,SCSI]
770 See header of drivers/scsi/gdth.c.
771
772 gpt [EFI] Forces disk with valid GPT signature but
773 invalid Protective MBR to be treated as GPT.
774
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 gvp11= [HW,SCSI]
776
777 hashdist= [KNL,NUMA] Large hashes allocated during boot
778 are distributed across NUMA nodes. Defaults on
779 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700780 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781
782 hcl= [IA-64] SGI's Hardware Graph compatibility layer
783
784 hd= [EIDE] (E)IDE hard drive subsystem geometry
785 Format: <cyl>,<head>,<sect>
786
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
788 size of <nn>. This works even on boxes that have no
789 highmem otherwise. This also works to reduce highmem
790 size on bigger boxes.
791
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800792 highres= [KNL] Enable/disable high resolution timer mode.
793 Valid parameters: "on", "off"
794 Default: "on"
795
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 hisax= [HW,ISDN]
797 See Documentation/isdn/README.HiSax.
798
Andi Kleenb4718e62008-07-23 21:27:51 -0700799 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
800 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700801 On x86-64 and powerpc, this option can be specified
802 multiple times interleaved with hugepages= to reserve
803 huge pages of different sizes. Valid pages sizes on
804 x86-64 are 2M (when the CPU supports "pse") and 1G
805 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700806 Note that 1GB pages can only be allocated at boot time
807 using hugepages= and not freed afterwards.
Nick Piggine11bfbf2008-07-23 21:27:52 -0700808 default_hugepagesz=
809 [same as hugepagesz=] The size of the default
810 HugeTLB page size. This is the size represented by
811 the legacy /proc/ hugepages APIs, used for SHM, and
812 default size when mounting hugetlbfs filesystems.
813 Defaults to the default architecture's huge page size
814 if not specified.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815
Paul Mundt6902aa82008-09-21 17:14:42 +0900816 hlt [BUGS=ARM,SH]
817
Jiri Kosina36d95732008-10-06 02:51:09 -0400818 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200820 i8042.dumbkbd [HW] Pretend that controller can only read data from
821 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 (Don't attempt to blink the leds)
823 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500824 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400825 i8042.noloop [HW] Disable the AUX Loopback command while probing
826 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 i8042.nomux [HW] Don't check presence of an active multiplexing
828 controller
829 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
830 controllers
831 i8042.panicblink=
832 [HW] Frequency with which keyboard LEDs should blink
833 when kernel panics (default is 0.5 sec)
834 i8042.reset [HW] Reset the controller during init and cleanup
835 i8042.unlock [HW] Unlock (ignore) the keylock
836
837 i810= [HW,DRM]
838
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700839 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
840 indicates that the driver is running on unsupported
841 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
843 does not match list of supported models.
844 i8k.power_status
845 [HW] Report power status in /proc/i8k
846 (disabled by default)
847 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
848 capability is set.
849
850 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
851 See Documentation/mca.txt.
852
853 icn= [HW,ISDN]
854 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
855
856 ide= [HW] (E)IDE subsystem
Greg Kroah-Hartmana594eeb2008-04-18 00:46:20 +0200857 Format: ide=nodma or ide=doubler
Randy Dunlap1c10e932008-03-07 21:53:50 +0100858 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
Randy Dunlap1c10e932008-03-07 21:53:50 +0100861 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862
Andi Kleenf039b752007-05-02 19:27:12 +0200863 idle= [X86]
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800864 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
Andi Kleenf039b752007-05-02 19:27:12 +0200865 Poll forces a polling idle loop that can slightly improves the performance
866 of waking up a idle CPU, but will use a lot of power and make the system
867 run hot. Not recommended.
868 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
869 to not use it because it doesn't save as much power as a normal idle
870 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
871 as idle=poll.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800872 idle=halt. Halt is forced to be used for CPU idle.
873 In such case C2/C3 won't be used again.
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800874 idle=nomwait. Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700875
Denis Cheng594765a2008-02-06 02:57:49 +0100876 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
877 Claim all unknown PCI IDE storage controllers.
878
Ingo Molnar792908222006-12-06 20:40:51 -0800879 ignore_loglevel [KNL]
880 Ignore loglevel setting - this will print /all/
881 kernel messages to the console. Useful for debugging.
882
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883 ihash_entries= [KNL]
884 Set number of hash buckets for inode cache.
885
886 in2000= [HW,SCSI]
887 See header of drivers/scsi/in2000.c.
888
889 init= [KNL]
890 Format: <full_path>
891 Run specified binary instead of /sbin/init as init
892 process.
893
894 initcall_debug [KNL] Trace initcalls as they are executed. Useful
895 for working out where the kernel is dying during
896 startup.
897
898 initrd= [BOOT] Specify the location of the initial ramdisk
899
900 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
901 Format: <irq>
902
903 inttest= [IA64]
904
Pavel Machekb552da82008-03-19 15:58:11 +0100905 iommu= [x86]
906 off
907 force
908 noforce
909 biomerge
910 panic
911 nopanic
912 merge
913 nomerge
914 forcesac
915 soft
916
917
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700918 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
919 off
920 Disable intel iommu driver.
921 igfx_off [Default Off]
922 By default, gfx is mapped as normal device. If a gfx
923 device has a dedicated DMAR unit, the DMAR unit is
924 bypassed by not enabling DMAR with this option. In
925 this case, gfx device will use physical address for
926 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700927 forcedac [x86_64]
928 With this option iommu will not optimize to look
929 for io virtual address below 32 bit forcing dual
930 address cycle on pci bus for cards supporting greater
931 than 32 bit addressing. The default is to look
932 for translation below 32 bit and if not available
933 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800934 strict [Default Off]
935 With this option on every unmap_single operation will
936 result in a hardware IOTLB flush operation as opposed
937 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700938
Rene Hermanb02aae92008-01-30 13:30:05 +0100939 io_delay= [X86-32,X86-64] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100940 0x80
941 Standard port 0x80 based delay
942 0xed
943 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100944 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100945 Simple two microseconds delay
946 none
947 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +0100948
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949 io7= [HW] IO7 for Marvel based alpha systems
950 See comment before marvel_specify_io7 in
951 arch/alpha/kernel/core_marvel.c.
952
953 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -0400954 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700955
956 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700957 See comment before ip2_setup() in
958 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959
960 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
961 See header of drivers/scsi/ips.c.
962
Simon Horman72c4a132006-09-13 19:57:18 -0700963 ports= [IP_VS_FTP] IPVS ftp helper module
964 Default is 21.
965 Up to 8 (IP_VS_APP_MAX_PORTS) ports
966 may be specified.
967 Format: <port>,<port>....
968
Alan Cox200803d2005-06-28 20:45:18 -0700969 irqfixup [HW]
970 When an interrupt is not handled search all handlers
971 for it. Intended to get systems with badly broken
972 firmware running.
973
974 irqpoll [HW]
975 When an interrupt is not handled search all handlers
976 for it. Also check all handlers each timer
977 interrupt. Intended to get systems with badly broken
978 firmware running.
979
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700981 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982
983 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800984 Format:
985 <cpu number>,...,<cpu number>
986 or
Li Zefanb225d442008-11-06 12:53:39 -0800987 <cpu number>-<cpu number>
988 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -0800989 or a mixture
990 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -0800991
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992 This option can be used to specify one or more CPUs
993 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -0800994 algorithms. You can move a process onto or off an
995 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996 <cpu number> begins at 0 and the maximum value is
997 "number of CPUs in system - 1".
998
999 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001000 alternative -- manually setting the CPU mask of all
1001 tasks in the system -- can cause problems and
1002 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003
Randy Dunlapa9913042005-10-23 12:57:11 -07001004 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005
1006 js= [HW,JOY] Analog joystick
1007 See Documentation/input/joystick.txt.
1008
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001009 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001010 specifies the amount of memory usable by the kernel
1011 for non-movable allocations. The requested amount is
1012 spread evenly throughout all nodes in the system. The
1013 remaining memory in each node is used for Movable
1014 pages. In the event, a node is too small to have both
1015 kernelcore and Movable pages, kernelcore pages will
1016 take priority and other nodes will have a larger number
1017 of kernelcore pages. The Movable zone is used for the
1018 allocation of pages that may be reclaimed or moved
1019 by the page migration subsystem. This means that
1020 HugeTLB pages may not be allocated from this zone.
1021 Note that allocations like PTEs-from-HighMem still
1022 use the HighMem zone if it exists, and the Normal
1023 zone if it does not.
1024
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001025 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gorman7e63efe2007-07-17 04:03:15 -07001026 is similar to kernelcore except it specifies the
1027 amount of memory used for migratable allocations.
1028 If both kernelcore and movablecore is specified,
1029 then kernelcore will be at *least* the specified
1030 value but may be more. If movablecore on its own
1031 is specified, the administrator must be careful
1032 that the amount of memory usable for all allocations
1033 is not too small.
1034
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 keepinitrd [HW,ARM]
1036
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001037 kstack=N [X86-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038 in oops dumps.
1039
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001040 kgdboc= [HW] kgdb over consoles.
1041 Requires a tty driver that supports console polling.
1042 (only serial suported for now)
1043 Format: <serial_device>[,baud]
1044
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001045 kmac= [MIPS] korina ethernet MAC address.
1046 Configure the RouterBoard 532 series on-chip
1047 Ethernet adapter MAC address.
1048
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049 l2cr= [PPC]
1050
Robert Brosea78bfbf2008-03-29 07:20:23 +11001051 l3cr= [PPC]
1052
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001053 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001054 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001056 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001057 C2 power state.
1058
FD Camifcb71f62008-01-06 19:08:56 +01001059 libata.dma= [LIBATA] DMA control
1060 libata.dma=0 Disable all PATA and SATA DMA
1061 libata.dma=1 PATA and SATA Disk DMA only
1062 libata.dma=2 ATAPI (CDROM) DMA only
1063 libata.dma=4 Compact Flash DMA only
1064 Combinations also work, so libata.dma=3 enables DMA
1065 for disks and CDROMs, but not CFs.
1066
Dave Jones78e70c22007-09-27 11:50:13 -04001067 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1068 when set.
1069 Format: <int>
1070
Tejun Heo33267322008-02-13 09:15:09 +09001071 libata.force= [LIBATA] Force configurations. The format is comma
1072 separated list of "[ID:]VAL" where ID is
1073 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1074 matching port, link or device. Basically, it matches
1075 the ATA ID string printed on console by libata. If
1076 the whole ID part is omitted, the last PORT and DEVICE
1077 values are used. If ID hasn't been specified yet, the
1078 configuration applies to all ports, links and devices.
1079
1080 If only DEVICE is omitted, the parameter applies to
1081 the port and all links and devices behind it. DEVICE
1082 number of 0 either selects the first device or the
1083 first fan-out link behind PMP device. It does not
1084 select the host link. DEVICE number of 15 selects the
1085 host link and device attached to it.
1086
1087 The VAL specifies the configuration to force. As long
1088 as there's no ambiguity shortcut notation is allowed.
1089 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1090 The following configurations can be forced.
1091
1092 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1093 Any ID with matching PORT is used.
1094
1095 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1096
1097 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1098 udma[/][16,25,33,44,66,100,133] notation is also
1099 allowed.
1100
1101 * [no]ncq: Turn on or off NCQ.
1102
Tejun Heo05944bd2008-08-13 20:19:09 +09001103 * nohrst, nosrst, norst: suppress hard, soft
1104 and both resets.
1105
Tejun Heo33267322008-02-13 09:15:09 +09001106 If there are multiple matching configurations changing
1107 the same attribute, the last one is used.
1108
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001110 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001112 lockd.nlm_grace_period=P [NFS] Assign grace period.
1113 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001115 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1116 Format: <integer>
1117
1118 lockd.nlm_timeout=T [NFS] Assign timeout value.
1119 Format: <integer>
1120
1121 lockd.nlm_udpport=M [NFS] Assign UDP port.
1122 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123
1124 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1125 Format: <irq>
1126
1127 loglevel= All Kernel Messages with a loglevel smaller than the
1128 console loglevel will be printed to the console. It can
1129 also be changed with klogd or other programs. The
1130 loglevels are defined as follows:
1131
1132 0 (KERN_EMERG) system is unusable
1133 1 (KERN_ALERT) action must be taken immediately
1134 2 (KERN_CRIT) critical conditions
1135 3 (KERN_ERR) error conditions
1136 4 (KERN_WARNING) warning conditions
1137 5 (KERN_NOTICE) normal but significant condition
1138 6 (KERN_INFO) informational
1139 7 (KERN_DEBUG) debug-level messages
1140
1141 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001142 Format: { n | nk | nM }
1143 n must be a power of two. The default size
1144 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145
Randy Dunlapaccaa242007-10-16 01:29:37 -07001146 logo.nologo [FB] Disables display of the built-in Linux logo.
1147 This may be used to provide more screen space for
1148 kernel log messages and is useful when debugging
1149 kernel boot problems.
1150
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151 lp=0 [LP] Specify parallel ports to use, e.g,
1152 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1153 lp=reset first parallel port). 'lp=0' disables the
1154 lp=auto printer driver. 'lp=reset' (which can be
1155 specified in addition to the ports) causes
1156 attached printers to be reset. Using
1157 lp=port1,port2,... specifies the parallel ports
1158 to associate lp devices with, starting with
1159 lp0. A port specification may be 'none' to skip
1160 that lp device, or a parport name such as
1161 'parport0'. Specifying 'lp=auto' instead of a
1162 port specification list means that device IDs
1163 from each port should be examined, to see if
1164 an IEEE 1284-compliant printer is attached; if
1165 so, the driver will manage that printer.
1166 See also header of drivers/char/lp.c.
1167
1168 lpj=n [KNL]
1169 Sets loops_per_jiffy to given constant, thus avoiding
1170 time-consuming boot-time autodetection (up to 250 ms per
1171 CPU). 0 enables autodetection (default). To determine
1172 the correct value for your kernel, boot with normal
1173 autodetection and see what value is printed. Note that
1174 on SMP systems the preset will be applied to all CPUs,
1175 which is likely to cause problems if your CPUs need
1176 significantly divergent settings. An incorrect value
1177 will cause delays in the kernel to be wrong, leading to
1178 unpredictable I/O errors and other breakage. Although
1179 unlikely, in the extreme case this might damage your
1180 hardware.
1181
1182 ltpc= [NET]
1183 Format: <io>,<irq>,<dma>
1184
Randy Dunlapa9913042005-10-23 12:57:11 -07001185 mac5380= [HW,SCSI] Format:
1186 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187
Randy Dunlapa9913042005-10-23 12:57:11 -07001188 machvec= [IA64] Force the use of a particular machine-vector
1189 (machvec) in a generic kernel.
1190 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191
Randy Dunlapa9913042005-10-23 12:57:11 -07001192 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 be mounted
1194 Format: <1-256>
1195
1196 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001197 should make use of. maxcpus=n : n >= 0 limits the
1198 kernel to using 'n' processors. n=0 is a special case,
1199 it is equivalent to "nosmp", which also disables
1200 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201
Randy Dunlap1c207f92008-11-19 15:36:16 -08001202 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1203 or equal to this physical address is ignored.
Bob Picco2b2c3752005-06-29 18:00:00 -07001204
Randy Dunlapa9913042005-10-23 12:57:11 -07001205 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206 Should be between 1 and 2^32-1.
1207
1208 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001209 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 Should be between 1 and 16384.
1211
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 mcatest= [IA-64]
1213
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001214 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215
Uwe Hermann71cced62008-10-20 09:32:21 -07001216 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001217
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 md= [HW] RAID subsystems devices and level
1219 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001220
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 mdacon= [MDA]
1222 Format: <first>,<last>
1223 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001224
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1226 Amount of memory to be used when the kernel is not able
1227 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001228 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229 address space collisions. Without memmap= PCI devices
1230 could be placed at addresses belonging to unused RAM.
1231
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001232 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 memory.
1234
Paul Mundt6902aa82008-09-21 17:14:42 +09001235 memchunk=nn[KMG]
1236 [KNL,SH] Allow user to override the default size for
1237 per-device physically contiguous DMA buffers.
1238
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001239 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001240 E820 memory map, as specified by the user.
1241 Such memmap=exactmap lines can be constructed based on
1242 BIOS output or other requirements. See the memmap=nn@ss
1243 option description.
1244
1245 memmap=nn[KMG]@ss[KMG]
1246 [KNL] Force usage of a specific region of memory
1247 Region of memory to be used, from ss to ss+nn.
1248
1249 memmap=nn[KMG]#ss[KMG]
1250 [KNL,ACPI] Mark specific memory as ACPI data.
1251 Region of memory to be used, from ss to ss+nn.
1252
1253 memmap=nn[KMG]$ss[KMG]
1254 [KNL,ACPI] Mark specific memory as reserved.
1255 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001256 Example: Exclude memory from 0x18690000-0x1869ffff
1257 memmap=64K$0x18690000
1258 or
1259 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001261 memory_corruption_check=0/1 [X86]
1262 Some BIOSes seem to corrupt the first 64k of
1263 memory when doing things like suspend/resume.
1264 Setting this option will scan the memory
1265 looking for corruption. Enabling this will
1266 both detect corruption and prevent the kernel
1267 from using the memory being corrupted.
1268 However, its intended as a diagnostic tool; if
1269 repeatable BIOS-originated corruption always
1270 affects the same memory, you can use memmap=
1271 to prevent the kernel from using that memory.
1272
1273 memory_corruption_check_size=size [X86]
1274 By default it checks for corruption in the low
1275 64k, making this memory unavailable for normal
1276 use. Use this parameter to scan for
1277 corruption in more or less memory.
1278
1279 memory_corruption_check_period=seconds [X86]
1280 By default it checks for corruption every 60
1281 seconds. Use this parameter to check at some
1282 other rate. 0 disables periodic checking.
1283
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001284 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001285 Format: <integer>
1286 range: 0,4 : pattern number
1287 default : 0 <disable>
1288
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 meye.*= [HW] Set MotionEye Camera parameters
1290 See Documentation/video4linux/meye.txt.
1291
Andres Salomon8f368812007-10-12 23:04:06 +02001292 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1293 Multi-Function General Purpose Timers on AMD Geode
1294 platforms.
1295
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001296 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1297 the BIOS has incorrectly applied a workaround. TinyBIOS
1298 version 0.98 is known to be affected, 0.99 fixes the
1299 problem by letting the user disable the workaround.
1300
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301 mga= [HW,DRM]
1302
Randy Dunlap1c207f92008-11-19 15:36:16 -08001303 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1304 physical address is ignored.
1305
Mel Gorman6b74ab92008-07-23 21:26:49 -07001306 mminit_loglevel=
1307 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1308 parameter allows control of the logging verbosity for
1309 the additional memory initialisation checks. A value
1310 of 0 disables mminit logging and a level of 4 will
1311 log everything. Information is printed at KERN_DEBUG
1312 so loglevel=8 may also need to be specified.
1313
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314 mousedev.tap_time=
1315 [MOUSE] Maximum time between finger touching and
1316 leaving touchpad surface for touch to be considered
1317 a tap and be reported as a left button click (for
1318 touchpads working in absolute mode only).
1319 Format: <msecs>
1320 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1321 reporting absolute coordinates, such as tablets
1322 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1323 reporting absolute coordinates, such as tablets
1324
1325 mpu401= [HW,OSS]
1326 Format: <io>,<irq>
1327
1328 MTD_Partition= [MTD]
1329 Format: <name>,<region-number>,<size>,<offset>
1330
Randy Dunlapa9913042005-10-23 12:57:11 -07001331 MTD_Region= [MTD] Format:
1332 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333
1334 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001335 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336
Ben Dooks9db829f2008-07-03 11:24:29 +01001337 mtdset= [ARM]
1338 ARM/S3C2412 JIVE boot control
1339
1340 See arch/arm/mach-s3c2412/mach-jive.c
1341
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001343 [HW] Make the MicroTouch USB driver use raw coordinates
1344 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345
1346 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1347
1348 NCR_D700= [HW,SCSI]
1349 See header of drivers/scsi/NCR_D700.c.
1350
1351 ncr5380= [HW,SCSI]
1352
1353 ncr53c400= [HW,SCSI]
1354
1355 ncr53c400a= [HW,SCSI]
1356
1357 ncr53c406a= [HW,SCSI]
1358
1359 ncr53c8xx= [HW,SCSI]
1360
1361 netdev= [NET] Network devices parameters
1362 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1363 Note that mem_start is often overloaded to mean
1364 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001365 This usage is only documented in each driver source
1366 file if at all.
1367
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001368 nf_conntrack.acct=
1369 [NETFILTER] Enable connection tracking flow accounting
1370 0 to disable accounting
1371 1 to enable accounting
1372 Default value depends on CONFIG_NF_CT_ACCT that is
1373 going to be removed in 2.6.29.
1374
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001376 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377
1378 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001379 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380
Trond Myklebusta72b4422006-01-03 09:55:41 +01001381 nfs.callback_tcpport=
1382 [NFS] set the TCP port on which the NFSv4 callback
1383 channel should listen.
1384
Trond Myklebust58df0952006-01-03 09:55:57 +01001385 nfs.idmap_cache_timeout=
1386 [NFS] set the maximum lifetime for idmapper cache
1387 entries.
1388
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001389 nfs.enable_ino64=
1390 [NFS] enable 64-bit inode numbers.
1391 If zero, the NFS client will fake up a 32-bit inode
1392 number for the readdir() and stat() syscalls instead
1393 of returning the full 64-bit number.
1394 The default is to return 64-bit inode numbers.
1395
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001396 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1397 when a NMI is triggered.
1398 Format: [state][,regs][,debounce][,die]
1399
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001400 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001402 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 emulation library even if a 387 maths coprocessor
1404 is present.
1405
Christoph Lameterc1aee212007-05-31 00:40:47 -07001406 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1407 caches in the slab allocator. Saves per-node memory,
1408 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001409
Randy Dunlapa9913042005-10-23 12:57:11 -07001410 noalign [KNL,ARM]
1411
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412 noapic [SMP,APIC] Tells the kernel to not make use of any
1413 IOAPICs that may be present in the system.
1414
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 nobats [PPC] Do not use BATs for mapping kernel lowmem
1416 on "Classic" PPC cores.
1417
1418 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001419
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001420 nodelayacct [KNL] Disable per-task delay accounting
1421
Linus Torvalds1da177e2005-04-16 15:20:36 -07001422 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1423
Paul Mundt6902aa82008-09-21 17:14:42 +09001424 nodsp [SH] Disable hardware DSP at boot time.
1425
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001426 noefi [X86-32,X86-64] Disable EFI runtime services support.
1427
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 noexec [IA-64]
1429
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001430 noexec [X86-32,X86-64]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001431 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001432 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001433 noexec=off: disable non-executable mappings
1434
1435 noexec32 [X86-64]
1436 This affects only 32-bit executables.
1437 noexec32=on: enable non-executable mappings (default)
1438 read doesn't imply executable mappings
1439 noexec32=off: disable non-executable mappings
1440 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441
Paul Mundt6902aa82008-09-21 17:14:42 +09001442 nofpu [SH] Disable hardware FPU at boot time.
1443
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001444 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001445 register save and restore. The kernel will only save
1446 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447
Andi Kleen191679f2008-01-30 13:33:21 +01001448 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1449
Paul Mundt6902aa82008-09-21 17:14:42 +09001450 nohlt [BUGS=ARM,SH]
Randy Dunlapa9913042005-10-23 12:57:11 -07001451
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001452 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453 instruction doesn't work correctly and not to
1454 use it.
1455
1456 nohalt [IA-64] Tells the kernel not to use the power saving
1457 function PAL_HALT_LIGHT when idle. This increases
1458 power-consumption. On the positive side, it reduces
1459 interrupt wake-up latency, which may improve performance
1460 in certain environments such as networked servers or
1461 real-time systems.
1462
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001463 nohz= [KNL] Boottime enable/disable dynamic ticks
1464 Valid arguments: on, off
1465 Default: on
1466
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001467 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468 disable unhandled interrupt sources.
1469
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001470 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001471 broken timer IRQ sources.
1472
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473 noisapnp [ISAPNP] Disables ISA PnP code.
1474
1475 noinitrd [RAM] Tells the kernel not to load any configured
1476 initial RAM disk.
1477
1478 nointroute [IA-64]
1479
Tony Luck0aa366f2007-07-20 11:22:30 -07001480 nojitter [IA64] Disables jitter checking for ITC timers.
1481
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001482 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001484 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001485
Suresh Siddha6e1cb382008-07-10 11:16:58 -07001486 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1487
Suresh Siddhaaf9d1382008-07-11 13:11:57 -07001488 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1489 default x2apic cluster mode on platforms
1490 supporting x2apic.
1491
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 noltlbs [PPC] Do not use large page/tlb entries for kernel
1493 lowmem mapping on PPC40x.
1494
Horms312f1f02006-02-22 09:57:55 +09001495 nomca [IA-64] Disable machine check abort handling
1496
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001497 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001498
Andres Salomon83d73842007-10-12 23:04:06 +02001499 nomfgpt [X86-32] Disable Multi-Function General Purpose
1500 Timer usage (for AMD Geode machines).
1501
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001502 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001503
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001504 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001505 with UP alternatives
1506
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 noresidual [PPC] Don't use residual data on PReP machines.
1508
Randy Dunlapa9913042005-10-23 12:57:11 -07001509 noresume [SWSUSP] Disables resume and restores original swap
1510 space.
1511
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 no-scroll [VGA] Disables scrollback.
1513 This is required for the Braillex ib80-piezo Braille
1514 reader made by F.H. Papenmeier (Germany).
1515
1516 nosbagart [IA-64]
1517
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001518 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001519
Len Brown61ec7562007-08-16 03:34:22 -04001520 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1521 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522
Dave Jones97842212007-07-15 23:41:05 -07001523 nosoftlockup [KNL] Disable the soft-lockup detector.
1524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 nosync [HW,M68K] Disables sync negotiation for all devices.
1526
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001527 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528
1529 nousb [USB] Disable the USB subsystem
1530
1531 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001532
Fenghua Yua6c75b862008-03-14 13:57:08 -07001533 nptcg= [IA64] Override max number of concurrent global TLB
1534 purges which is reported from either PAL_VM_SUMMARY or
1535 SAL PALO.
1536
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001537 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1538 one of ['zone', 'node', 'default'] can be specified
1539 This can be set from sysctl after boot.
1540 See Documentation/sysctl/vm.txt for details.
1541
Dave Jonesa61c2d72006-01-07 23:18:19 +00001542 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1543
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001544 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1545 Rather than timing out after 20 ms if an EC
1546 command is not properly ACKed, override the length
1547 of the timeout. We have interrupts disabled while
1548 waiting for the ACK, so if this is set too high
1549 interrupts *may* be lost!
1550
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551 opl3= [HW,OSS]
1552 Format: <io>
1553
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 oprofile.timer= [HW]
1555 Use timer interrupt instead of performance counters
1556
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557 osst= [HW,SCSI] SCSI Tape Driver
1558 Format: <buffer_size>,<write_threshold>
1559 See also Documentation/scsi/st.txt.
1560
1561 panic= [KNL] Kernel behaviour on panic
1562 Format: <timeout>
1563
1564 parkbd.port= [HW] Parallel port number the keyboard adapter is
1565 connected to, default is 0.
1566 Format: <parport#>
1567 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1568 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001569 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570
Randy Dunlapa9913042005-10-23 12:57:11 -07001571 parport= [HW,PPT] Specify parallel ports. 0 disables.
1572 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1573 Use 'auto' to force the driver to use any
1574 IRQ/DMA settings detected (the default is to
1575 ignore detected IRQ/DMA settings because of
1576 possible conflicts). You can specify the base
1577 address, IRQ, and DMA settings; IRQ and DMA
1578 should be numbers, or 'auto' (for using detected
1579 settings on that particular port), or 'nofifo'
1580 (to avoid using a FIFO even if it is detected).
1581 Parallel ports are assigned in the order they
1582 are specified on the command line, starting
1583 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584
Randy Dunlapa9913042005-10-23 12:57:11 -07001585 parport_init_mode= [HW,PPT]
1586 Configure VIA parallel port to operate in
1587 a specific mode. This is necessary on Pegasos
1588 computer where firmware has no options for setting
1589 up parallel port mode and sets it to spp.
1590 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591 Format: [spp|ps2|epp|ecp|ecpepp]
1592
Randy Dunlapa9913042005-10-23 12:57:11 -07001593 pas2= [HW,OSS] Format:
1594 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1595
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 pas16= [HW,SCSI]
1597 See header of drivers/scsi/pas16.c.
1598
Andrew Mortondd287792006-03-23 03:00:57 -08001599 pause_on_oops=
1600 Halt all CPUs after the first oops has been printed for
1601 the specified number of seconds. This is to be used if
1602 your oopses keep scrolling off the screen.
1603
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 pcbit= [HW,ISDN]
1605
1606 pcd. [PARIDE]
1607 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001608 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609
Randy Dunlapa9913042005-10-23 12:57:11 -07001610 pci=option[,option...] [PCI] various PCI subsystem options:
Andi Kleenc0115602008-08-22 09:53:39 +02001611 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001612 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001613 the hardware directly. Use this if your machine
1614 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001615 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001616 hardware access methods are allowed. Use this
1617 if you experience crashes upon bootup and you
1618 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001619 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001620 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001621 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001622 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001623 noaer [PCIE] If the PCIEAER kernel config parameter is
1624 enabled, this kernel boot option can be used to
1625 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001626 nodomains [PCI] Disable support for multiple PCI
1627 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001628 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001629 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001630 nomsi [MSI] If the PCI_MSI kernel config parameter is
1631 enabled, this kernel boot option can be used to
1632 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001633 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001634 routing table. These calls are known to be buggy
1635 on several machines and they hang the machine
1636 when used, but on other computers it's the only
1637 way to get the interrupt routing table. Try
1638 this option if the kernel is unable to allocate
1639 IRQs or discover secondary PCI buses on your
1640 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001641 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001642 Use with caution as certain devices share
1643 address decoders between ROMs and other
1644 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001645 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001646 expansion ROMs that do not already have
1647 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001648 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001649 assigned automatically to PCI devices. You can
1650 make the kernel exclude IRQs of your ISA cards
1651 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001652 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001653 of the PIRQ table (normally generated
1654 by the BIOS) if it is outside the
1655 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001656 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001657 useful if the kernel is unable to find your
1658 secondary buses and you want to tell it
1659 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001660 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001661 numbers ourselves, overriding
1662 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001663 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001664 in the BIOS $PIR table. This is needed on
1665 some systems with broken BIOSes, notably
1666 some HP Pavilion N5400 and Omnibook XE3
1667 notebooks. This will have no effect if ACPI
1668 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001669 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001670 or for PCI scanning.
Andi Kleenc0115602008-08-22 09:53:39 +02001671 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001672 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001673 routeirq Do IRQ routing for all PCI devices.
1674 This is normally done in pci_enable_device(),
1675 so this option is a temporary workaround
1676 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001677 skip_isa_align [X86] do not align io start addr, so can
1678 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001679 firmware [ARM] Do not re-enumerate the bus but instead
1680 just use the configuration from the
1681 bootloader. This is currently used on
1682 IXP2000 systems where the bus has to be
1683 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001684 noearly [X86] Don't do any early type 1 scanning.
1685 This might help on some broken boards which
1686 machine check when some devices' config space
1687 is read. But various workarounds are disabled
1688 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001689 bfsort Sort PCI devices into breadth-first order.
1690 This sorting is done to get a device
1691 order compatible with older (<= 2.4) kernels.
1692 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001693 cbiosize=nn[KMG] The fixed amount of bus space which is
1694 reserved for the CardBus bridge's IO window.
1695 The default value is 256 bytes.
1696 cbmemsize=nn[KMG] The fixed amount of bus space which is
1697 reserved for the CardBus bridge's memory
1698 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001699
Chuck Ebberte5665a42008-09-24 20:40:34 -04001700 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1701 Management.
1702 off Disable ASPM.
1703 force Enable ASPM even on devices that claim not to support it.
1704 WARNING: Forcing ASPM on may cause system lockups.
1705
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706 pcmv= [HW,PCMCIA] BadgePAD 4
1707
1708 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001709 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001710
1711 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1712 boot time.
1713 Format: { 0 | 1 }
1714 See arch/parisc/kernel/pdc_chassis.c
1715
1716 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001717 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718
1719 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001720 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721
1722 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001723 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724
1725 plip= [PPT,NET] Parallel port network link
1726 Format: { parport<nr> | timid | 0 }
1727 See also Documentation/parport.txt.
1728
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001729 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1730 Override pmtimer IOPort with a hex value.
1731 e.g. pmtmr=0x508
1732
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06001733 pnp.debug [PNP]
1734 Enable PNP debug messages. This depends on the
1735 CONFIG_PNP_DEBUG_MESSAGES option.
1736
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 pnpacpi= [ACPI]
1738 { off }
1739
1740 pnpbios= [ISAPNP]
1741 { on | off | curr | res | no-curr | no-res }
1742
1743 pnp_reserve_irq=
1744 [ISAPNP] Exclude IRQs for the autoconfiguration
1745
1746 pnp_reserve_dma=
1747 [ISAPNP] Exclude DMAs for the autoconfiguration
1748
1749 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001750 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751
1752 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001753 [ISAPNP] Exclude memory regions for the
1754 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755 Ranges are in pairs (memory base and size).
1756
Jason Baron346e15b2008-08-12 16:46:19 -04001757 dynamic_printk
1758 Enables pr_debug()/dev_dbg() calls if
1759 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1760 be switched on/off via <debugfs>/dynamic_printk/modules
1761
Ingo Molnar45807a12007-07-15 23:40:10 -07001762 print-fatal-signals=
1763 [KNL] debug: print fatal signals
1764 print-fatal-signals=1: print segfault info to
1765 the kernel console.
1766 default: off.
1767
Randy Dunlape84845c2007-07-15 23:40:25 -07001768 printk.time= Show timing data prefixed to each printk message line
1769 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1770
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001772 Format: [schedule,]<number>
1773 Param: "schedule" - profile schedule points.
1774 Param: <number> - step/bucket size as a power of 2 for
1775 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001776 Param: "sleep" - profile D-state sleeping (millisecs).
1777 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001778 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779
Randy Dunlapa9913042005-10-23 12:57:11 -07001780 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001781 Limit processor to maximum C-state
1782 max_cstate=9 overrides any DMI blacklist limit.
1783
Len Brown41c0d862005-12-28 12:43:51 -05001784 processor.nocst [HW,ACPI]
1785 Ignore the _CST method to determine C-states,
1786 instead using the legacy FADT method
1787
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1789 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001790 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791
Randy Dunlapa9913042005-10-23 12:57:11 -07001792 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1793 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1795 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001796 psmouse.resetafter= [HW,MOUSE]
1797 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798 (0 = never).
1799 psmouse.resolution=
1800 [HW,MOUSE] Set desired mouse resolution, in dpi.
1801 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001802 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803 0 = disabled, 1 = enabled (default).
1804
1805 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001806 Format:
1807 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001808
1809 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001810 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811
Kay Sieversdc8c8582007-08-15 12:25:38 +02001812 pty.legacy_count=
1813 [KNL] Number of legacy pty's. Overwrites compiled-in
1814 default number.
1815
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001816 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001817
Linus Torvalds1da177e2005-04-16 15:20:36 -07001818 r128= [HW,DRM]
1819
1820 raid= [HW,RAID]
1821 See Documentation/md.txt.
1822
Randy Dunlapa9913042005-10-23 12:57:11 -07001823 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001824 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001825
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001827 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001828
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001829 rcupdate.blimit= [KNL,BOOT]
1830 Set maximum number of finished RCU callbacks to process
1831 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001832
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001833 rcupdate.qhimark= [KNL,BOOT]
1834 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001835 RCU callbacks over which batch limiting is disabled.
1836
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001837 rcupdate.qlowmark= [KNL,BOOT]
1838 Set threshold of queued RCU callbacks below which
1839 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001840
Olof Johanssonffdfc402005-09-06 15:17:19 -07001841 rdinit= [KNL]
1842 Format: <full_path>
1843 Run specified binary instead of /init from the ramdisk,
1844 used for early userspace startup. See initrd.
1845
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001846 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001847 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001848 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849
Paul Jackson46b6d942008-07-04 10:00:09 -07001850 relax_domain_level=
1851 [KNL, SMP] Set scheduler's default relax_domain_level.
1852 See Documentation/cpusets.txt.
1853
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1855
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001856 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07001857 Format: nn[KMG]
1858 Reserves a hole at the top of the kernel virtual
1859 address space.
1860
Vivek Goyal7e962872006-09-27 01:50:44 -07001861 reset_devices [KNL] Force drivers to reset the underlying device
1862 during initialization.
1863
Randy Dunlapa9913042005-10-23 12:57:11 -07001864 resume= [SWSUSP]
1865 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001867 resume_offset= [SWSUSP]
1868 Specify the offset from the beginning of the partition
1869 given by "resume=" at which the swap header is located,
1870 in <PAGE_SIZE> units (needed only for swap files).
1871 See Documentation/power/swsusp-and-swap-files.txt
1872
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001873 retain_initrd [RAM] Keep initrd memory after extraction
1874
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875 rhash_entries= [KNL,NET]
1876 Set number of hash buckets for route cache
1877
1878 riscom8= [HW,SERIAL]
1879 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1880
1881 ro [KNL] Mount root device read-only on boot
1882
1883 root= [KNL] Root filesystem
1884
1885 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1886 mount the root filesystem
1887
1888 rootflags= [KNL] Set root filesystem mount option string
1889
1890 rootfstype= [KNL] Set root filesystem type
1891
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001892 rootwait [KNL] Wait (indefinitely) for root device to show up.
1893 Useful for devices that are detected asynchronously
1894 (e.g. USB and MMC devices).
1895
James Morris20510f22007-10-16 23:31:32 -07001896 root_plug.vendor_id=
1897 [ROOTPLUG] Override the default vendor ID
1898
1899 root_plug.product_id=
1900 [ROOTPLUG] Override the default product ID
1901
1902 root_plug.debug=
1903 [ROOTPLUG] Enable debugging output
1904
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905 rw [KNL] Mount root device read-write on boot
1906
1907 S [KNL] Run init in single mode
1908
1909 sa1100ir [NET]
1910 See drivers/net/irda/sa1100_ir.c.
1911
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001913
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1915 Format: <io>[,<timeout>[,<isapnp>]]
1916
1917 scsi_debug_*= [SCSI]
1918 See drivers/scsi/scsi_debug.c.
1919
1920 scsi_default_dev_flags=
1921 [SCSI] SCSI default device flags
1922 Format: <integer>
1923
1924 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1925 Format: <vendor>:<model>:<flags>
1926 (flags are integer value)
1927
Randy Dunlap6af66322007-11-14 16:52:25 -08001928 scsi_logging_level= [SCSI] a bit mask of logging levels
1929 See drivers/scsi/scsi_logging.h for bits. Also
1930 settable via sysctl at dev.scsi.logging_level
1931 (/proc/sys/dev/scsi/logging_level).
1932 There is also a nice 'scsi_logging_level' script in the
1933 S390-tools package, available for download at
1934 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001936 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1937 discovered. async scans them in kernel threads,
1938 allowing boot to proceed. none ignores them, expecting
1939 user space to do the scan.
1940
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941 selinux [SELINUX] Disable or enable SELinux at boot time.
1942 Format: { "0" | "1" }
1943 See security/selinux/Kconfig help text.
1944 0 -- disable.
1945 1 -- enable.
1946 Default value is set via kernel config option.
1947 If enabled at boot time, /selinux/disable can be used
1948 later to disable prior to initial policy load.
1949
James Morris4e5ab4c2006-06-09 00:33:33 -07001950 selinux_compat_net =
1951 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001952 Format: { "0" | "1" }
1953 0 -- use new secmark-based packet controls
1954 1 -- use legacy packet controls
1955 Default value is 0 (preferred).
1956 Value can be changed at runtime via
1957 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001958
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001959 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960
Linus Torvalds1da177e2005-04-16 15:20:36 -07001961 shapers= [NET]
1962 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001963
Yinghai Lub05f78f2008-08-22 01:32:50 -07001964 show_msr= [x86] show boot-time MSR settings
1965 Format: { <integer> }
1966 Show boot-time (BIOS-initialized) MSR settings.
1967 The parameter means the number of CPUs to show,
1968 for example 1 means boot CPU only.
1969
Linus Torvalds1da177e2005-04-16 15:20:36 -07001970 sim710= [SCSI,HW]
1971 See header of drivers/scsi/sim710.c.
1972
1973 simeth= [IA-64]
1974 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001975
Linus Torvalds1da177e2005-04-16 15:20:36 -07001976 slram= [HW,MTD]
1977
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001978 slub_debug[=options[,slabs]] [MM, SLUB]
1979 Enabling slub_debug allows one to determine the
1980 culprit if slab objects become corrupted. Enabling
1981 slub_debug can create guard zones around objects and
1982 may poison objects when not in use. Also tracks the
1983 last alloc / free. For more information see
1984 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001985
1986 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001987 Determines the maximum allowed order for slabs.
1988 A high setting may cause OOMs due to memory
1989 fragmentation. For more information see
1990 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001991
1992 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001993 The minimum number of objects per slab. SLUB will
1994 increase the slab order up to slub_max_order to
1995 generate a sufficiently large slab able to contain
1996 the number of objects indicated. The higher the number
1997 of objects the smaller the overhead of tracking slabs
1998 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001999 For more information see Documentation/vm/slub.txt.
2000
2001 slub_min_order= [MM, SLUB]
2002 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002003 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002004 For more information see Documentation/vm/slub.txt.
2005
2006 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002007 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002008 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002009 allocs to different slabs. Debug options disable
2010 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002011 For more information see Documentation/vm/slub.txt.
2012
Linus Torvalds1da177e2005-04-16 15:20:36 -07002013 smart2= [HW]
2014 Format: <io1>[,<io2>[,...,<io8>]]
2015
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002016 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002017 attempt to substitute SMP alternatives once at boot.
2018
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002019 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2020 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2021 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2022 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2023 smsc-ircc2.ircc_irq= [HW] IRQ line
2024 smsc-ircc2.ircc_dma= [HW] DMA channel
2025 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2026 0: Toshiba Satellite 1800 (GP data pin select)
2027 1: Fast pin select (default)
2028 2: ATC IRMode
2029
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030 snd-ad1816a= [HW,ALSA]
2031
2032 snd-ad1848= [HW,ALSA]
2033
2034 snd-ali5451= [HW,ALSA]
2035
2036 snd-als100= [HW,ALSA]
2037
2038 snd-als4000= [HW,ALSA]
2039
2040 snd-azt2320= [HW,ALSA]
2041
2042 snd-cmi8330= [HW,ALSA]
2043
2044 snd-cmipci= [HW,ALSA]
2045
2046 snd-cs4231= [HW,ALSA]
2047
2048 snd-cs4232= [HW,ALSA]
2049
2050 snd-cs4236= [HW,ALSA]
2051
2052 snd-cs4281= [HW,ALSA]
2053
2054 snd-cs46xx= [HW,ALSA]
2055
2056 snd-dt019x= [HW,ALSA]
2057
2058 snd-dummy= [HW,ALSA]
2059
2060 snd-emu10k1= [HW,ALSA]
2061
2062 snd-ens1370= [HW,ALSA]
2063
2064 snd-ens1371= [HW,ALSA]
2065
2066 snd-es968= [HW,ALSA]
2067
2068 snd-es1688= [HW,ALSA]
2069
2070 snd-es18xx= [HW,ALSA]
2071
2072 snd-es1938= [HW,ALSA]
2073
2074 snd-es1968= [HW,ALSA]
2075
2076 snd-fm801= [HW,ALSA]
2077
2078 snd-gusclassic= [HW,ALSA]
2079
2080 snd-gusextreme= [HW,ALSA]
2081
2082 snd-gusmax= [HW,ALSA]
2083
2084 snd-hdsp= [HW,ALSA]
2085
2086 snd-ice1712= [HW,ALSA]
2087
2088 snd-intel8x0= [HW,ALSA]
2089
2090 snd-interwave= [HW,ALSA]
2091
2092 snd-interwave-stb=
2093 [HW,ALSA]
2094
2095 snd-korg1212= [HW,ALSA]
2096
2097 snd-maestro3= [HW,ALSA]
2098
2099 snd-mpu401= [HW,ALSA]
2100
2101 snd-mtpav= [HW,ALSA]
2102
2103 snd-nm256= [HW,ALSA]
2104
2105 snd-opl3sa2= [HW,ALSA]
2106
2107 snd-opti92x-ad1848=
2108 [HW,ALSA]
2109
2110 snd-opti92x-cs4231=
2111 [HW,ALSA]
2112
2113 snd-opti93x= [HW,ALSA]
2114
2115 snd-pmac= [HW,ALSA]
2116
2117 snd-rme32= [HW,ALSA]
2118
2119 snd-rme96= [HW,ALSA]
2120
2121 snd-rme9652= [HW,ALSA]
2122
2123 snd-sb8= [HW,ALSA]
2124
2125 snd-sb16= [HW,ALSA]
2126
2127 snd-sbawe= [HW,ALSA]
2128
2129 snd-serial= [HW,ALSA]
2130
2131 snd-sgalaxy= [HW,ALSA]
2132
2133 snd-sonicvibes= [HW,ALSA]
2134
2135 snd-sun-amd7930=
2136 [HW,ALSA]
2137
2138 snd-sun-cs4231= [HW,ALSA]
2139
2140 snd-trident= [HW,ALSA]
2141
2142 snd-usb-audio= [HW,ALSA,USB]
2143
2144 snd-via82xx= [HW,ALSA]
2145
2146 snd-virmidi= [HW,ALSA]
2147
2148 snd-wavefront= [HW,ALSA]
2149
2150 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002151
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002152 softlockup_panic=
2153 [KNL] Should the soft-lockup detector generate panics.
2154
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2156 See Documentation/sonypi.txt
2157
2158 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002159 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160
2161 spia_io_base= [HW,MTD]
2162 spia_fio_base=
2163 spia_pedr=
2164 spia_peddr=
2165
2166 sscape= [HW,OSS]
2167 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002168
Linus Torvalds1da177e2005-04-16 15:20:36 -07002169 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2170 See Documentation/scsi/st.txt.
2171
Linus Torvalds1da177e2005-04-16 15:20:36 -07002172 sti= [PARISC,HW]
2173 Format: <num>
2174 Set the STI (builtin display/keyboard on the HP-PARISC
2175 machines) console (graphic card) which should be used
2176 as the initial boot-console.
2177 See also comment in drivers/video/console/sticore.c.
2178
2179 sti_font= [HW]
2180 See comment in drivers/video/console/sticore.c.
2181
2182 stifb= [HW]
2183 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2184
Greg Banks42a7fc42007-03-06 01:42:23 -08002185 sunrpc.pool_mode=
2186 [NFS]
2187 Control how the NFS server code allocates CPUs to
2188 service thread pools. Depending on how many NICs
2189 you have and where their interrupts are bound, this
2190 option will affect which CPUs will do NFS serving.
2191 Note: this parameter cannot be changed while the
2192 NFS server is running.
2193
2194 auto the server chooses an appropriate mode
2195 automatically using heuristics
2196 global a single global pool contains all CPUs
2197 percpu one pool for each CPU
2198 pernode one pool for each NUMA node (equivalent
2199 to global on non-NUMA machines)
2200
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002202
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203 switches= [HW,M68k]
2204
2205 sym53c416= [HW,SCSI]
2206 See header of drivers/scsi/sym53c416.c.
2207
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002208 sysrq_always_enabled
2209 [KNL]
2210 Ignore sysrq setting - this boot parameter will
2211 neutralize any effect of /proc/sys/kernel/sysrq.
2212 Useful for debugging.
2213
Linus Torvalds1da177e2005-04-16 15:20:36 -07002214 t128= [HW,SCSI]
2215 See header of drivers/scsi/t128.c.
2216
2217 tdfx= [HW,DRM]
2218
David Brownell77437fd2008-07-23 21:28:33 -07002219 test_suspend= [SUSPEND]
2220 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2221 standby suspend) as the system sleep state to briefly
2222 enter during system startup. The system is woken from
2223 this state using a wakeup-capable RTC alarm.
2224
Linus Torvalds1da177e2005-04-16 15:20:36 -07002225 thash_entries= [KNL,NET]
2226 Set number of hash buckets for TCP connection
2227
Len Brownf8707ec2007-08-12 00:12:54 -04002228 thermal.act= [HW,ACPI]
2229 -1: disable all active trip points in all thermal zones
2230 <degrees C>: override all lowest active trip points
2231
Len Brownc52a7412007-08-14 15:49:32 -04002232 thermal.crt= [HW,ACPI]
2233 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002234 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002235
Len Brownf5487142007-08-12 00:12:44 -04002236 thermal.nocrt= [HW,ACPI]
2237 Set to disable actions on ACPI thermal zone
2238 critical and hot trip points.
2239
Len Brown72b33ef2007-08-12 00:12:17 -04002240 thermal.off= [HW,ACPI]
2241 1: disable ACPI thermal control
2242
Len Browna70cdc52007-08-12 00:12:35 -04002243 thermal.psv= [HW,ACPI]
2244 -1: disable all passive trip points
2245 <degrees C>: override all passive trip points to this value
2246
Len Brown730ff342007-08-12 00:12:26 -04002247 thermal.tzp= [HW,ACPI]
2248 Specify global default ACPI thermal zone polling rate
2249 <deci-seconds>: poll all this frequency
2250 0: no polling (default)
2251
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252 tmscsim= [HW,SCSI]
2253 See comment before function dc390_setup() in
2254 drivers/scsi/tmscsim.c.
2255
2256 tp720= [HW,PS2]
2257
2258 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002259 Format:
2260 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2261
Randy Dunlapa9913042005-10-23 12:57:11 -07002262 turbografx.map[2|3]= [HW,JOY]
2263 TurboGraFX parallel port interface
2264 Format:
2265 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002266 See also Documentation/input/joystick-parport.txt
2267
2268 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2269 See header of drivers/scsi/u14-34f.c.
2270
2271 uart401= [HW,OSS]
2272 Format: <io>,<irq>
2273
2274 uart6850= [HW,OSS]
2275 Format: <io>,<irq>
2276
Alan Stern5f8364b2006-12-05 16:29:55 -05002277 uhci-hcd.ignore_oc=
2278 [USB] Ignore overcurrent events (default N).
2279 Some badly-designed motherboards generate lots of
2280 bogus events, for ports that aren't wired to
2281 anything. Set this parameter to avoid log spamming.
2282 Note that genuine overcurrent events won't be
2283 reported either.
2284
Simon Arlotte3a61b02008-07-19 23:32:54 +01002285 unknown_nmi_panic
2286 [X86-32,X86-64]
2287 Set unknown_nmi_panic=1 early on boot.
2288
Alan Sternb5e795f2007-02-20 15:00:53 -05002289 usbcore.autosuspend=
2290 [USB] The autosuspend time delay (in seconds) used
2291 for newly-detected USB devices (default 2). This
2292 is the time required before an idle device will be
2293 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002294 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002295
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002296 usbcore.usbfs_snoop=
2297 [USB] Set to log all usbfs traffic (default 0 = off).
2298
2299 usbcore.blinkenlights=
2300 [USB] Set to cycle leds on hubs (default 0 = off).
2301
2302 usbcore.old_scheme_first=
2303 [USB] Start with the old device initialization
2304 scheme (default 0 = off).
2305
2306 usbcore.use_both_schemes=
2307 [USB] Try the other device initialization scheme
2308 if the first one fails (default 1 = enabled).
2309
2310 usbcore.initial_descriptor_timeout=
2311 [USB] Specifies timeout for the initial 64-byte
2312 USB_REQ_GET_DESCRIPTOR request in milliseconds
2313 (default 5000 = 5.0 seconds).
2314
Linus Torvalds1da177e2005-04-16 15:20:36 -07002315 usbhid.mousepoll=
2316 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002317
Paul Jackson200001e2008-06-25 05:44:46 -07002318 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2319 kernel's map of available physical RAM.
2320
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002321 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002322 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002323 vdso=1: enable VDSO (default)
2324 vdso=0: disable VDSO mapping
2325
Roland McGrathaf65d642008-01-30 13:30:43 +01002326 vdso32= [X86-32,X86-64]
2327 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2328 vdso32=1: enable 32-bit VDSO (default)
2329 vdso32=0: disable 32-bit VDSO mapping
2330
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002331 vector= [IA-64,SMP]
2332 vector=percpu: enable percpu vector domain
2333
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334 video= [FB] Frame buffer configuration
2335 See Documentation/fb/modedb.txt.
2336
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002337 vga= [BOOT,X86-32] Select a particular video mode
Uwe Hermann71cced62008-10-20 09:32:21 -07002338 See Documentation/x86/i386/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002339 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002340 Use vga=ask for menu.
2341 This is actually a boot loader parameter; the value is
2342 passed to the kernel using a special protocol.
2343
Randy Dunlapa9913042005-10-23 12:57:11 -07002344 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345 size of <nn>. This can be used to increase the
2346 minimum size (128MB on x86). It can also be used to
2347 decrease the size and leave more room for directly
2348 mapped kernel RAM.
2349
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002350 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2351 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002353 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2354 Format: <command>
2355
2356 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2357 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002358
Linus Torvalds1da177e2005-04-16 15:20:36 -07002359 waveartist= [HW,OSS]
2360 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002361
Linus Torvalds1da177e2005-04-16 15:20:36 -07002362 wd33c93= [HW,SCSI]
2363 See header of drivers/scsi/wd33c93.c.
2364
2365 wd7000= [HW,SCSI]
2366 See header of drivers/scsi/wd7000.c.
2367
2368 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002369 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370
2371 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2372 xd_geo= See header of drivers/block/xd.c.
2373
2374 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002375 Format:
2376 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002377
Andi Kleena62eaf12006-02-16 23:41:58 +01002378 norandmaps Don't use address space randomization
2379 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2380
Randy Dunlapa9913042005-10-23 12:57:11 -07002381______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002382
2383TODO:
2384
2385 Add documentation for ALSA options.
2386 Add more DRM drivers.